Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
a retrospective review of clinical records of late postpartum eclampsia patients who had presented with acute onset of visual and/or neurological symptoms to the emergency department of a medical college hospital in south india between april 2009 and may 2013 was done .
all patients had underwent mri with diffusion weighted imaging ( dwi ) and apparent diffusion coefficient ( adc ) mapping to differentiate vasogenic from cytotoxic cerebral edema .
patient records were analyzed for presence of visual symptoms , peak systolic and diastolic blood pressures , associated neurological symptoms , location of mri lesions and time taken for recovery .
the mr images were graded for extent and severity of cortex and white matter vasogenic edema , degree of confluence , mass effect and ventricular distortion on a scale from 1 to 5 .
statistical analysis was performed using chi - square test and a p value of less than 0.05 was considered to be statistically significant .
clinical and imaging findings are summarized in table 1 . clinical profile of patients with pres the 10 patients ranged in age from 21 to 32 years ( average-26  3.49 years ) .
mean peak systolic and diastolic blood pressures were 144  21.71 and 93  9.19 mm of hg , respectively .
bilateral visual loss was noted in five patients of whom three patients were able to perceive hand movements and two patients had only perception of light .
the most common abnormality noted on mri included bilateral symmetrical hyperintensities on t2-weighted images and fluid attenuated inversion recovery ( flair ) sequences in the parieto - occipital regions [ figs . 1 and 2 ] .
dwi showed high signal intensity with no areas of restricted diffusion while adc mapping did not show corresponding low signal intensity thus suggesting vasogenic edema .
axial mr image ( fluid attenuated inversion recovery ) showing confluent edema in subcortical and deep white matter ( grade 4 ) seen as hyperintensities in bilateral parieto - occipital lobes ( patient 6 ) axial mr image ( fluid attenuation inversion recovery ) showing edema in subcortical white matter ( grade 2 ) seen as hyperintensities in bilateral occipital lobes ( patient 9 ) five patients had additional abnormalities in the cerebellar hemispheres and three patients had involvement of frontal lobes . average time taken for visual recovery was 2.6  1.34 days .
follow - up mri in four patients after 1 month revealed complete resolution of these abnormalities . in the remaining , clinical symptoms and signs
follow - up scans were not performed due to financial constraints . the extent of cerebral edema in patients with and without visual loss was compared and results summarized in table 2 .
posterior reversible encephalopathy syndrome ( pres ) is a rare neurotoxic state that presents with altered mental status , headache , seizures , and visual disturbances along with neuroimaging features of vasogenic edema involving the posterior cerebral circulation .
although several cases of pres have been reported in neurology and neuroradiology literature , exposure in ophthalmic literature has been rather limited .
the causes of pres are diverse and include pre - eclampsia , eclampsia , renal insufficiency , solid organ transplantation and immunosuppressive therapy .
hypertensive encephalopathy is said to be the cause of this syndrome which has been demonstrated by various clinical and experimental studies .
patients with hypertensive encephalopathy have the same clinical signs as those with pres and they also have rapid resolution of clinical and imaging abnormalities once the blood pressure is lowered .
the most widely accepted theory states that sudden elevation of blood pressure causes failure of autoregulation in the cerebral blood vessels leading to hyperperfusion , breakdown of blood brain barrier , and vasogenic edema . the posterior circulation is preferentially affected since it has less sympathetic innervation than the carotid circulation , thus rendering it less able to adjust to blood pressure fluctuations . however , this theory is not comprehensive because pres can affect normotensives .
high degree of suspicion is required in these patients of late postpartum eclampsia because it occurs between 48 hours postpartum and 1 month after delivery frequently in women who have had a normal pregnancy and delivery and no signs of a pre - eclamptic syndrome .
alternative theory implicates endothelial dysfunction as the cause for occurrence of pres in eclampsia and sepsis .
this is supported by the fact that elevations in markers of endothelial dysfunction such as lactate dehydrogenase and abnormal red blood cell fragmentation have been reported in pres .
vasospasm with subsequent ischemia has also been hypothesized to cause loss of integrity of the blood brain barrier in eclampsia .
although reversible by definition early recognition and prompt treatment is essential to prevent secondary complications like intracerebral hemorrhage and infarction .
a large retrospective study of pres in diverse clinical situations revealed the occurrence of visual symptoms in 20% and headache in 26% while seizures was observed in 74% of cases .
the visual disturbances reported with pres include cortical blindness , visual neglect , homonymous hemianopia and blurred vision .
cortical visual loss was observed in five of our patients ( 50% ) while the remaining denied any visual disturbances .
our findings are in line with liman et al . , who observed that visual disturbances like cortical blindness , blurred vision and hemianopia are more common in eclampsia related pres ( 50% ) .
patients with pres due to other etiologies more often present with severe symptoms like altered mental status or neurological deficit and lesser visual disturbances ( 27.8% ) .
roth et al . , have also reported a higher percentage of disturbed vision in pre - eclampsia - eclampsia - related pres .
this could be because of the younger age and lesser associated comorbidities in these patients as compared to patients with pres due to other etiologies .
all patients ( with / without visual loss ) demonstrated bilateral symmetrical hyperintensities in the parieto - occipital regions on t2-weighted images .
this feature along with predominant involvement of the white matter distinguishes this syndrome from bilateral posterior cerebral artery territory infarction .
although several studies have reported visual symptoms of varying degrees in pres , to the best of our knowledge no study has attempted to correlate the visual symptoms with imaging abnormalities .
the limitations of our study include its retrospective design , and smaller sample size of postpartum eclampsia patients .
we conclude that there is a higher prevalence of cortical visual loss in patients with pres associated with late postpartum eclampsia .
patients with higher degree of vasogenic edema of the posterior cerebral white matter might present with visual loss .
ophthalmologists should be aware of this clinical entity since it is reversible and readily treated by controlling the blood pressure .
further prospective studies comprising larger sample size and different etiologies of pres are warranted in this regard .

Answer:
the purpose of this study was to determine the prevalence of visual disturbances in patients with posterior reversible encephalopathy syndrome ( pres ) associated with late postpartum eclampsia .
 we retrospectively reviewed the clinical records of late postpartum eclampsia patients with features of pres for the presence of visual disturbances and location of radiological abnormalities .
 we found a higher prevalence of cortical visual loss in patients with pres associated with late postpartum eclampsia .
 bilateral symmetrical vasogenic edema of the parieto - occipital lobe was the most common magnetic resonance imaging ( mri ) abnormality noted .
 no significant differences were observed in the extent of edema in patients with and without visual loss .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
in february 2012 , the birmingham and solihull tb service noted 2 distinct 24-loci miru - vntr strain types of mycobacterium tuberculosis ( clusters a and b ) isolated from 4 eritrea - born patients with pulmonary tb .
the diagnoses were made in july ( cluster a ) and december 2011 ( cluster b ) .
epidemiologic links were considered to be patients naming each other as contacts , sharing a contact without naming each other , or sharing a location during the infectious period of 1 patient .
case managers interviewed patients to elicit names of persons they may have had regular contact with over the infectious period ; contacts in nonhousehold settings ( e.g. , workplace , leisure sites ) were also included , but geographic locations were not always defined .
the infectious period was defined as the date of onset of respiratory symptoms , if known , or 3 months before diagnosis .
surveillance data revealed an increased number of eritrea - born tb patients ( 1 , 4 , and 19 cases in 2004 , 2006 , and 2011 respectively ) ; estimated incidence was 960 cases per 100,000 persons . to investigate whether transmission had occurred in the united kingdom and to identify opportunities for wider community intervention , we invited all eritrea - born tb patients ( with and without strain typing available ) reported during 2004august 2012 for an extended interview with a dedicated tb nurse .
semistructured questions examined potential sources of infection and secondary cases . to systematically explore locations frequented by patients ,
nurses asked patients to complete a 24-hour work / rest / play diary . since november 2011
, extended interviews have been routinely conducted for all miru - vntr clustered tb patients in birmingham ; no ethics approval was required . according to routine practice , clustered eritrea - born patients continued to be interviewed through december 2013 .
most patients were male ( 65% ) and had pulmonary tb ( 67% ) ; median age was 29 ( interquartile range 2535 ) years , and median length of time in the united kingdom before diagnosis was 4 ( interquartile range 25 ) years .
of 62 ( 71% ) patients who could be located , 49 participated in extended interviews . except for homelessness ( 1 patient ) , no other social risk factors ( e.g. , drug and/or alcohol misuse , imprisonment , or mental health problems ) were noted .
socializing occurred mainly in places of worship ( 43/49 patients frequented 9 places of worship ) and private homes ( 10/49 patients frequented 7 residences ) .
miru - vntr typing was available for all 61 culture - confirmed cases ; 46 isolates had 24 loci , and 15 isolates had 15 loci ( table 1 ) .
of the isolates with 24 loci , 27 ( 59% ) clustered in 6 strain types . to identify risk factors for strain - type clustering , we compared demographic characteristics of clustered and nonclustered patients ( table 2 ) . according to bivariable analysis results ,
a noncongregate location was significantly associated with cluster a only ( table 2 ) . * miru - vntr , mycobacterial interspersed repetitive units variable - number tandem - repeat ; na , not applicable .
no epidemiologic links between those from different countries were found except in cluster e.   15-loci miru - vntr typing was available beginning in 2003 .
iqr , interquartile range ; bcg , bacillus calmette - gurin ; miru - vntr , mycobacterial interspersed repetitive units variable - number tandem - repeat ; na , not applicable ; rv , religious venue ; tb , tuberculosis .  fisher exact test ,
the figure shows the overlap of social networks and miru - vntr strain - type clusters for eritrea - born tb patients .
few cases were linked by routine contact investigation alone because patients named the place of congregation ( designated as religious venue [ rv ] 1 in the figure ) in different ways .
the extended interviews defined geographic locations to street level , and it was determined that rv1 was used for multidenominational worship and therefore was recognized by different names .
routine contact investigation also failed to elicit other households where patients socialized ( h58 in the figure ) .
as a result of the study , location - based contact tracing at rv1 was undertaken .
an additional 68 persons were assessed , of which 19 ( 28% ) had latent tb ( 16 started treatment and 14 completed treatment ) and 1 had active tb .
latent tb was confirmed by a single interferon- release assay ; therefore , infection resulting from distant exposure could not be ruled out .
social network of eritrea - born patients with tb in relation to 6 distinct 24-loci miru - vntr strain - type clusters and associated cluster members born elsewhere , united kingdom , january 2009december 2013 .
nonclustered eritrean patients are included if > 1 epidemiologic link to clustered patients is known .
circles denote eritrea - born patients ; triangles denote patients born elsewhere ; solid squares denote places of social mixing . for patients ,
labels denote strain type cluster ( a  f ; x , no strain typing available ) and chronological order of case notification within each strain type cluster . for places ,
labels denote type ( h , private home ; rv , religious venue ; sc , school ; wp , workplace ) .
double lines with arrows denote connections between tb patients who named each other as contacts during routine contact tracing investigations .
detached symbols at the bottom indicate persons for whom no epidemiologic links to any other case were detected .
miru - vntr , mycobacterial interspersed repetitive units variable - number tandem - repeat ; tb , tuberculosis . combined strain typing and in - depth interviewing also uncovered apparent casual transmission involving cluster e at a workplace ( wp1 in the figure ) .
six months before diagnosis , patient e2 had worked at wp1 for 2 weeks , during the infectious period of patient e1 . as a result , 5 new workplace contacts were investigated ; 3 cases were diagnosed ( no patients were born in the united kingdom , and interferon- release assay conversion was not documented ) , and these patients completed treatment for latent tb . a third case ( in patient f5 ) occurred at wp1 , 6 months after illness of patient e2 , but the isolate from patient f5 was of a different strain type . given the low probability of transmission , no further location - based contact tracing was undertaken at wp1 .
discrepant strain types between patients known to have socialized at rv2 , rv3 , and school ( sc ) 1 also suggested that these cases did not involve the same chain of transmission .
the infectious period for patient b1 preceded the arrival of patient b2 in birmingham , and local transmission was thought to be unlikely ; both patients originated from the same town in eritrea .
genetically homogenous strain lineages prevalent in the countries of origin may falsely cluster persons from the migrant population ( 10 ) ; in our study , no patients within cluster d could be linked despite extensive epidemiologic investigation .
we have demonstrated the value of identifying places of social mixing during contact investigation for recognizing such microepidemics early . this approach has been found useful in other settings ( 11,12 ) .
a recent evaluation of the tb strain typing service in the united kingdom found that strain typing did not significantly affect time to diagnosis or the median number of secondarily infected persons found per index case ( 13 ) .
however , strain typing can highlight gaps in current contact investigation procedures in specific patient populations and can help focus resources on scenarios in which recent transmission is more likely . whole - genome sequencing may offer the ability to identify more recent strain evolution and transmission ( 14 ) .
conventional epidemiologic methods should be improved to complement molecular epidemiologic methods and increase their effect on tb control .

Answer:
to determine if local transmission was responsible for rising tuberculosis incidence in a recently dispersed migrant community in birmingham , uk , during 20042013 , we conducted enhanced epidemiologic investigation of molecular clusters .
 this technique identified exact locations of social mixing and chains of apparent recent transmission , which can be helpful for directing resources .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
the first and second vertebrae ( atlas and axis , respectively ) are different from others with their function and anatomy .
normally , the intervertebral disc is located between two vertebrae , but not located between atlas and axis .
the most common cervical vertebrae anomalies ( cvas ) are fusion and posterior arch deficiency ( pad ) .
the second ( c2 ) and third ( c3 ) cervical vertebrae are most commonly influenced by fusion .
posterior arch anomalies occur probably the result of a locally decreased blood supply during fetal development .
skeletal deviations in maxillofacial region , head and neck posture deformities , cervical inclination , and orthopedic findings can be associated with malocclusion .
several studies declared the relation between the cervical vertebrae morphology and position of the mandible .
cva is often asymptomatic , for this reason , patients may notice anomalies with decrease age or an injury
the pathologic condition may reveal with the radiographic examination . although orthodontists do not have to be experts in cva
these patients should be directed to the experts early as possible and prevents progressively degenerative neurologic defects .
the present study is the first report to determine the frequency of cvas in orthodontic patients with dental malocclusions .
the aims of this study were to investigate the distribution of cvas among angle class i , ii , and iii malocclusions in a turkish patient population and whether a correlation between cva and dental malocclusion ; thus , being the first series of cvas in our population described in the english literature .
a power analysis conducted using the g*power version 3.1.7 . software ( franz faul , universitt kiel , germany ) indicated that a total sample size of 150 patients would give more than 80% power ( actual power = 0.8229 ) to detect significant differences with an effect size of 0.30 at an  = 0.05 level of significance ( critical  = 11.0705 ; noncentrality parameter  = 13.5000 ) .
the study was performed on 318 patients clinical records ( case histories , lateral cephalometric radiographs , and study models ) which were taken in archive at the department of orthodontics , faculty of dentistry , kirikkale university .
if an accurate diagnosis of the cva could not be made from these records , the subject was excluded from the study .
exclusion criteria included the patients , who were less than 18 years of age , had records with poor quality radiographs , had craniofacial anomaly and systemic muscle or joint disorder and , wound , burns , or scarring in the head and neck .
subjects were selected according to the following criteria : turkish with turkish grandparents , no history of trauma , and previous orthodontic treatment , study models including the first molars and standardized lateral cephalometric radiographs with the first five cervical vertebrae visible .
a total of 341 subjects were included in the study , but 23 subjects with developmental anomalies were excluded .
the radiographs of the patients were obtained with the teeth in occlusion , the lips in a relaxed position in a standardized head posture ( the frankfort plane parallel to the horizontal ) .
the radiographs were taken by an experienced x - ray technician using an orthopantograph ( planmeca proline cc 2002 , helsinki , finland ) with a film - to - focus distance of 165 cm and a film - to - median plane distance of 15 cm .
dental malocclusion groups observed through molar relationship in plaster models were divided into angle class i , ii , and iii according to angle 's classification .
angle class i : normal relationship of the molars ( mesiobuccal cusp of the upper molar occludes in buccal groove of the lower molar ) , but a line of occlusion incorrect because of malposed teeth , rotation , or other causes .
angle class ii : lower molar distally positioned relative to upper molar , a line of occlusion not specified .
angle class iii : lower molar mesially positioned relative to upper molar , a line of occlusion not specified .
cvas were categorized and recorded for all patients : fusion was defined as no intradiscal radiolucency or osseous continuities without complete separation between two cervical vertebrae .
pad was defined as a uniform radio - opacity without an internal cortical outline at the posterior arch of the cervical vertebra .
the lateral cephalograms were examined by an orthodontist ( h.k . ) and a dentomaxillofacial radiologist ( e.y . ) simultaneously . to determine errors in the methods ,
20% of the subjects with or without cva were selected randomly.first , each radiograph was separately evaluated by authors , but a final examination was done together , so a sentence was made to decide .
in addition , the same examiners twice reevaluated all of the radiographs after 4 weeks of the first evaluation .
a paired t - test was applied to both the first set and a second set of measurements , and no significant difference was found between the two sets .
intra - examiner reproducibility was found to be 90 and 92% , respectively , and the agreement between both investigators was 95% .
the chi - square and fisher 's exact test were used to determine the potential differences in the distribution of dental malocclusions , and genders when stratified by cvas .
pearson 's correlation test was used to determine the correlation between cvas and different parameters ( dental malocclusions and genders ) .
all of the statistical analyzes were performed with the spss software package ( spss version 16.0 , spss inc .
, 233 south wacker drive , 11 floor , chicago , il , usa ) . a p < 0.05 was considered statistically significant .
the final sample of 318 patients was examined ( 170 females and 148 males , mean age ; 20  0.9 years from 18 and 29 years ) . of these 318 patients , 98 ( 30.81% )
had angle class i , 124 ( 38.99% ) had angle class ii , and 96 ( 30.18% ) had angle class iii malocclusion .
cva was observed in 42 individuals ( of which 26 [ 8.1% ] had fusion and 16 [ 5.0% ] had pad ) , with a frequency of 13.2% .
of the 26 fusion defect , 8 ( 30.8% ) had angle class i , 8 ( 30.8% ) had angle class ii , and 10 ( 38.4% ) had angle class iii malocclusion .
of the 16 pad , 8 ( 50% ) had angle class i , 8 ( 50% ) had angle class ii but no patients with angle class iii malocclusion was observed .
the distribution of dental malocclusions regarding cvas was not statistically significant ( p = 0.076 ) [ table 1 ] .
the distribution of cvas according to dental malocclusions of these 42 individuals with cva , 52.3% ( 15 fusions and 7 pad ) were females and 47.7% ( 11 fusions and 9 pad ) were males .
the cvas and the gender were also compared [ table 2 ] and no statistically significant differences were found ( p = 0.339 ) . as shown in table 3 , statistically significant negative correlation ( p = 0.025 )
was found among cvas and dental malocclusions , but no statistically significant correlation was found between cvas and genders .
according to the sample size calculation for a power of 0.80 at  = 0.05 significant level , 150 subjects would be sufficient . at baseline
, there were 341 subjects for this study group ; twenty - three subjects in the study group have been excluded from the study . at the end of the study , there were 318 patients for the study group .
correlation between cva and vertebrae morphology , craniofacial malformations , and skeletal malocclusions were reported in the previous studies .
the aims of our study were to identify the prevalence of cva in turkish population and also whether there is a correlation between cva and dental malocclusion . in our study ,
the prevalence of fusion and pad were found 8.1% and 5.0% , respectively [ table 1 ] . besides , a statistically significant correlation ( p = 0.025 ) was found among cva and dental malocclusions [ table 3 ] .
the prevalence of cva was reported with a wide range of 0 - 61.4% in the literature .
sonnesen and kjaer reported that the incidence of fusion ( 61.4% ) more common in skeletal class iii patients and skeletal horizontal overjet when compared with control group ( 14.3% ) .
they revealed that if a skeletal horizontal overjet was caused by maxillary retrognathia , the decreased prevalence of fusion more likely seen .
reported that the descending distribution of cva were determined in skeletal class i , ii , and iii malocclusion , respectively ( 17 ) .
in addition , a higher prevalence of c1 level partial cleft and occipitalization was reported in their study .
our study was designed to investigate dental malocclusion , but the previous studies were planned to examine skeletal anomalies . to the best of our knowledge , this is the first study evaluate the frequency and distribution of cvas in orthodontic patients with dental malocclusions .
had stated that the angle of the cranial base and the head posture deviations were sexually dimorphic , females showing larger cervicohorizontal , and cranial base angles than males .
in addition , they reported that the relation between the cervical column fusion and cranial base angle , the inclination of the upper cervical spine and cervical lordosis were determined in females .
hence , it could be hypothesized that cervical column fusion has a dimorphic pattern in their occurrence .
in contrast , some researchers affirmed that there was no significant relation between gender and the occurrence of cva in their studies .
so that , our findings supports the studies showing no gender dimorphism [ table 2 ] .
it is not clear why vertebral anomalies occur and why these anomalies occur in different craniofacial morphology groups and skeletal malocclusion traits .
the genetic studies and insight of the early embryogenesis might be essential to understand the etiology of the cva . the recent studies affirmed that the notochord may be responsible to these anomalies . because the vertebral bodies were formed around the notochord in the prenatal period .
besides , the jaws develop from the migration of the neural crest cells to the craniofacial area before the notochord is surrounded by bone tissue . however , the association between the precise signaling of notochord to the neural crest and the migration of the neural crest cells to the craniofacial area is still unknown .
lateral cephalograms are usually used in orthodontic clinics to planning pretreatment and examined the postorthodontic treatment results .
early diagnose of these pathologies on cephalograms can provide essential documentation to the patient due to symptoms , injury , aging , and progression of the degenerative process
. however , two - dimensional radiographs may not be valid in the diagnosis of cva , because of the superimposition of the spine inclination and radiographic overlapping of the facets .
for this reason , the suspectable sign of cva on cephalogram is reevaluated with three - dimensional imaging systems like cone beam computed tomography to prevent misdiagnose .

 the prevalence of fusion and pad were found 8.1% and 5.0% in turkish population , respectivelystatistically significant differences were found among the dental malocclusions , and no statistically significant correlation between cva and angle class i , ii , and iii malocclusionno statistically significant differences were also found between the genders , and no statistically significant correlation between cva and genders were found .
  the prevalence of fusion and pad were found 8.1% and 5.0% in turkish population , respectively statistically significant differences were found among the dental malocclusions , and no statistically significant correlation between cva and angle class i , ii , and iii malocclusion no statistically significant differences were also found between the genders , and no statistically significant correlation between cva and genders were found .

Answer:
aims : the aims of our study were to investigate the distribution of cervical vertebrae anomalies ( cvas ) among dental angle class i , ii , and iii malocclusions in turkish population and whether a correlation between cva and dental malocclusion.materials and methods : the study was performed on lateral cephalometric radiographs which were taken at the department of orthodontics , faculty of dentistry , kirikkale university .
 the final sample of 318 orthodontic patients was included in the study .
 dental malocclusions were performed according to angle classification .
 cvas were categorized : ( 1 ) fusion and ( 2 ) posterior arch deficiency ( pad ) .
 the chi - square test was used to the analysis of the potential differences among dental malocclusions.results:the final sample of 318 patients was examined .
 cva was observed in 42 individuals ( of 26 [ 8.17% ] had fusion and 16 [ 5.03% ] had pad ) , with a frequency of 13.2% .
 of the 26 fusion defect , 8 ( 30.7% ) had angle class i , 8 ( 30.7% ) had angle class ii , and 10 ( 38.4% ) had angle class iii malocclusion .
 of the 16 pad , 8 ( 50% ) had angle class i , 8 ( 50% ) had angle class ii but no patients with angle class iii malocclusion was observed .
 the distribution of dental malocclusions regarding cva was not statistically significant ( p = 0.076 ) .
 of these 42 individuals with cva , 52.3% ( 15 fusions and 7 pad ) were females and 47.7% ( 11 fusions and 9 pad ) were males.conclusion:in our study , the prevalence of fusion and pad were found 8.1% and 5.0% in turkish population , respectively . besides , no statistically significant correlation between cva and angle class i , ii , and iii malocclusions were found .
 our findings support the studies showing no gender dimorphism .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
substantial improvement in survival of people living with hiv has been observed with the introduction of antiretroviral therapy ( art ) in sub - saharan africa .
however , the introduction of art has led to new immune - mediated complications from dysfunction of the recovering immune system , termed immune reconstitution inflammatory syndrome ( iris ) . in patients with cryptococcal meningitis ( cm ) , a very common opportunistic infection in sub - saharan africa ,
iris is a frequent complication that is most often associated with exaggerated inflammatory responses in the central nervous system .
although cm remains the most common cause of adult meningitis in the overall population in sub - saharan africa , there are only a few recognized , reported cases of gastrointestinal ( gi ) involvement with cryptococcus in the literature .
an hiv - infected patient on art with a history of recent cm presented with chronic abdominal pain , thickened ileum , and abdominal lymphadenopathy .
he was initially treated for abdominal tuberculosis ( tb ) but later , he was shown to have a histologically confirmed cryptococcoma in the ileum . the major objective of this case report is to highlight the challenges in diagnosis and management of intra - abdominal cryptococcosis , especially in the setting of recent initiation of art .
a 37 year old hiv - positive male was initially diagnosed and treated for cm in may of 2009 with amphotericin induction therapy for 2 weeks followed by fluconazole 400  mg / day .
he had a protracted hospital course lasting 4 weeks because of persistently high intracranial hypertension despite sterilization of his cerebrospinal fluid , and he , required repeated therapeutic lumber punctures .
he started art ( zidovudine , lamivudine , and efavirenz ) on the 11th june 2009 with a baseline cd4 count of 5  cells/l . at day + 21 of art
, he reported abdominal pain with hypogastric tenderness that was empirically treated as urinary tract infection with a 5  day course of ciprofloxacin , and he noted some improvement . his cd4 count at the time had risen to 29  cells/l . at day + 35 of art ,
his general exam was unremarkable , except for a tachypnea of 28 breaths per minute .
the patient was managed as a possible atypical pneumonia with doxycycline , and his respiratory symptoms improved . however , the abdominal pain persisted intermittently with occasional vomiting . at day + 84 of art and in view of the persistent abdominal pain and an occasional dry cough ,
another chest radiograph was performed to exclude tb , which was also unremarkable . at this time ,
his cd4 was only 14  cells/l , and the hiv-1 viral load was 22,000  copies / ml . he reported 100% adherence to his art , and pill counts verified his adherence . at day + 112 of art , the patient still had similar complaints of abdominal pain and occasional vomiting .
repeat cd4 was 8  cells/l , and the viral load was minimally decreased at 15,475  copies / ml . the patient initially declined an ultrasound - guided biopsy but consented to the procedure at day + 140 of art .
this second ultrasound revealed a thickened ileum up to 6 mm , with adjacent 1  cm lymph nodes .
two biopsy specimens from the lymph nodes demonstrated no abnormality at histology . at day + 168 , the patient still had the same complaints with almost unchanged cd4 of 24  cells/l and viral load of 23,755  copies / ml .
he was presumed to be failing art , possibly due to poor absorptive surface because of the thickened gut wall .
a decision was made to initiate empiric anti - tb treatment for possible gastrointestinal tb .
after one week of tb empiric therapy , the patient presented with an acute abdomen , having signs of focal peritonitis in the right iliac fossa .
an upright abdominal radiograph demonstrated evidence of perforation with free air visible under the right hemidiaphram .
an emergency laparotomy was performed , revealing fecal matter with purulent fluid , adhesions , pneumoperitonium , and intestinal perforation at 10  cm proximal to the ileocecal junction .
the confirmatory histopathology report received 2 weeks later revealed a cryptococcoma in the ileal wall as the cause of the perforation with exuberant inflammation demonstrated by the multinucleated giant cell ( figs . 2 and 3 on hematoxylin and eosin stain and figs . 4 and 5 on periodic acid - schiff stain ) .
the patient 's marked clinical improvement after surgery , the lack of any evidence of cryptococcal infection elsewhere in the body especially in the central nervous system and a well formed granuloma formed the basis for the patient 's continuation with maintenance dose of fluconazole 200  mg / day under observation .
at this point , his tb medications were stopped and he was switched to second line art with subsequent viral suppression . through december 2014 , he continues to remain in care on second line art without any complaints .
we have presented a 37 year old hiv positive male , with a history of recent cm who subsequently developed chronic abdominal pain , eventually manifesting as a cryptococcoma of the ileum .
after treatment for cm and initiating art , he had presented with chronic abdominal pain and low grade fever without diarrhea .
he subsequently developed an intestinal perforation and presented with an acute surgical abdomen requiring bowel resection .
we suspected an iris phenomena , in accordance with the patient presentation shortly after initiation of art , recent history of cm , and exuberant inflammation in the granuloma on histology .
although , the initial immune recovery coupled with falling hiv-1 viral loads is consistent with iris , the subsequent virological failure makes the diagnosis of paradoxical iris less clear . in cryptococcosis ,
ideally , intra - operative cultures would have been performed which could have helped distinguish iris from cryptococcal relapse , based on culture sterility vs. growth , respectively .
cryptococcus organisms can be acquired in the gut primarily through hematogenous dissemination   or less commonly through direct inoculation during paracentesis or via a neurosurgical shunt .
the presentation in these gi cases of cryptococcal infection is usually vague , as seen in our patient , with subacute fevers , constitutional symptoms , asthenia , and anorexia .
virtually every intra - abdominal organ has been reported to be affected by cryptococcal infection .
the diagnosis of gi cryptococcosis requires a high index of suspicion , yet as in this case , clinicians may often initially focus on other common etiologies in immunocompromised persons , such as tb .
although abdominal tb was found to be the most common diagnosis in patients with hiv / aids presenting with chronic abdominal pain and abdominal lymphadenopathy , these studies were conducted predominantly in persons without cryptococcosis . among persons with a known pre - existing opportunistic infection , such as cm , the pre - test probability changes as paradoxical iris enters into the differential diagnosis . in our case ,
the characteristics of granulomas found in hiv - infected persons varies depending on whether or not they are receiving art . in pulmonary cryptococcomas ,
persons not receiving art demonstrate yeast proliferation with a histiocytic response but only minor lymphocytic and neutrophilic components .
conversely , cryptococcal granulomas in persons on art are characterized by the presence of cd4 t cells , greater response of histiocytes , and multinucleated giant - cell formation , as demonstrated in our patient .
there is a paucity of evidenced - based data for the management of cryptococcomas . in our case ,
the initial abdominal lymph node biopsy ( 5 weeks prior to the perforation ) did not reveal a diagnosis .
the question raised is , if we had confirmed the diagnosis of gi cryptococcoma before the perforation , would we have been able to effectively intervene . to answer this question
, it might be important to know if the cryptococcoma were due to iris or cryptococcal relapse .
could the patient have benefited from immunosuppressive therapy to treat iris and perhaps , avoid the perforation , or would more enhanced fungal therapy be needed to eradicate the cryptococcus ?
two case reports have described cryptococcomas due to paradoxical iris ; one in the brain   and the other in the retroperitoneal abdomen . in both cases
, they simply observed the patients but also emphasized the importance of confirming sterility of contents in the cryptococcoma by culture . in a case report by katchanov et al .
, a similar presentation of a central nervous system cryptococcoma was initially treated with antifungals exclusively with radiological worsening until steroids were added to direct therapy at paradoxical iris .
we have previously reported the challenges and dangers of using corticosteroids for cm because they may be contraindicated in cases of fluconazole - resistant cryptococcal relapse .
surgery , corticosteroids , and interferon - gamma have been tried in iris - like cryptococcomas due cryptococcus gattii
 .
empiric tb therapy , including rifampin , could have induced the metabolism of fluconazole , possibly lowering plasma levels by ~50% . these lower levels may have removed the fungistatic control of the cryptococcus , precipitating the perforation . however , after the surgery , the patient was observed on secondary prophylaxis doses of fluconazole , and he did well . to treat a cryptococcoma in the setting of recent initiation of art , where iris versus relapse can not be determined due to the absence of culture results , treatment with a combination of enhanced antifungal therapy and anti - inflammatory therapy
gi cryptococcosis has been described as a rare occurrence , with only a few published case reports .
we have discussed an hiv - infected patient with profound immunosuppression and recent cm who developed a gi cryptococcoma during initial immune recovery followed by virological failure after initiation of art .
the cryptococcoma was not identified and he developed perforation of the ileum , requiring surgery . we anticipate that with the roll out of art in sub - sahara africa , we are bound to see rare presentations of some of common conditions such as cm .
we recommend that health workers have a high index of suspicion for unusual complications of opportunistic infections in the setting of art - associated iris .
often treatment of iris requires only observation or anti - inflammatory drugs , but the presence of active infection needs to be excluded .
the authors declared no potential conflicts of interest with respect to the research , authorship , and/or publication of this article .

Answer:
the introduction of antiretroviral therapy ( art ) may lead to unusual paradoxical and unmasking presentations of opportunistic infections .
 intra - abdominal cryptococcosis is a rare manifestation of cryptococcus .
 we present the case of an hiv - infected patient on art , with a history of cryptococcal meningitis who presented with subacute , worsening abdominal pain during immune recovery .
 this evolved into chronic abdominal pain , with thickened bowel , and abdominal lymphadenopathy , while receiving empiric tuberculosis treatment . at 6-months , he developed intestinal perforation due to a histologically confirmed cryptococcoma .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
left ventricular thrombus ( lvt ) is one of the most common complications of myocardial infarction ( mi ) .
the incidence of lvt in patients with acute anterior mis in the prethrombolytic era is ranged from 20% to 40% and with a non anterior acute myocardial infarction ( ami ) and the risk of lvt was < 5% . although controversial , in the contemporary era of routine early revascularization and more aggressive anticoagulation , the incidence of lvt complicating as an anterior ami is likely reduced and is currently estimated at 5 - 15% .
the risk factors for the development of lvt are consistently irrespective of infarct treatment and include large infarct size , severe apical akinesia , or dyskinesia left ventricular ( lv ) aneurysm , and anterior mi . two - dimensional transthoracic echocardiography is the imaging modality used most often for assessing the presence , shape , and size of an lv mural thrombus with an excellent specificity of 85 - 90% and sensitivity of 95% .
here , we report a case of 40-year - old male patient who is presented in emergency department with the complaint of substernal chest pain radiating to left arm and back associated with sweating for the last 1 day , there was no history of dyspnea , palpitation , any limb weakness , or any history suggestive of transient ischemic attack and peripheral embolization .
his 12-lead electrocardiogram was suggestive of inferior wall mi [ figure 1 ] . his total leukocyte and eosinophil counts were normal , prothrombin time / international normalized ratio and activated partial thromboplastin time were normal , and other tests for hypercoagulable states were planned for the follow - up evaluation .
a transthoracic echocardiogram was performed bedside which revealed hypokinesia of basal , mid inferior , and inferoseptal wall [ figure 2 and video 1 ] .
surprisingly , it also revealed a mobile mass which is the most probably thrombus attached to hypokinetic inferobasal septum just near the lv outflow tract ( lvot ) [ figure 3 and video 2 ] . considering the possibility
that this mass was high risk for embolism , we planned for coronary angiogram followed by the surgical extraction of possible thrombus .
however , unfortunately , despite the proper counseling and explanation of the risk of embolism , the patient refused for further intervention and got discharged against medical advice .
small arrows showing hypokinesia of basal inferior septum , large arrow indicates left ventricle probable thrombus apical four chambers view
thrombi formation at basal interventricular septum near lvot is extremely rare as it is a region of high - velocity blood flow .
traditionally , the causes of lvt formation after acute st - segment elevation mi include segmental dysfunction of the infracted myocardium resulting in the stasis of blood , endocardial tissue inflammation that provides a thrombogenic surface and a hypercoagulable state .
the higher mortality has been reported in patients with lv thrombi after infarction , especially when these develop within the first 48 h after infarction .
the treatment for cardiac mass is a prompt surgical resection of the mass with the patients placed on cardiopulmonary bypass .
therefore , better understanding of the circumstances in which lv thrombosis occurs may influence the patient management . in our case ,
thrombus formed at the very unusual site and could lead to dreaded complication for the patient .
the possible etiology of thrombus formation , in our case , is hypokinesia of basal septum due to mi , but the presence of a subtle septal rupture which is not detectable on echocardiography could not be ruled out .

Answer:
left ventricular ( lv ) thrombus formation is a frequent complication in patients with acute anterior myocardial infarction ( mi ) .
 its incidence is lower with inferior wall mi . risk factors for the development of lv thrombus are consistently irrespective of infarct treatment and include large infarct size , severe apical akinesia or dyskinesia lv aneurysm , and anterior mi .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
age , gender , oral hygiene practices , and smoking are among the important risk factors that can affect the initiation , progression , and severity of periodontitis . the prevalence and severity of periodontal disease is found to increase with age .
furthermore , lack of oral hygiene encourages plaque formation , which leads to increase in pathogenic bacteria that are associated with severe forms of periodontal disease . since time immemorial
, tooth brushing has been considered ideal for maintaining a good oral hygiene . despite the relationship between tooth brushing and periodontal disease being unclear ; the breakthrough came in with rajala et al . reporting the disease to be more prevalent in sporadic toothbrush users than otherwise .
additionally , a positive association between tooth brushing and low periodontal disease prevalence has been confirmed in some studies .
studies suggest that the smokers are 11 times more likely than non - smokers to harbor the bacteria that cause periodontal disease and are 4 times more likely to have advanced periodontitis .
the sebha city is situated in south - western libya with a population of about 1,30,000 and people come from various urban areas surrounding it ; therefore , it has a heterogeneous society with a low level of health education . as per leous periodontal disease
is one of the main problems in libya ; bleeding , dental calculus and shallow pockets is prevalent in almost all the young adults .
it is also worth while to note that some of the 18-year - old male never clean their teeth with a toothbrush .
the periodontal disease data from several countries collected by using cpitn , is stored in the who global oral health data bank .
the sebha city belongs to the countries of the regional office for eastern mediterranean ( emro ) .
the oral health data for emro countries is available for the ages ; 15 years , 17 years , 15 - 19 years , 16 - 20 years , 35 - 44 years , and 65 - 44 years .
usually , epidemiological studies are primarily concentrated on adolescents , adults , and elderly population .
unfortunately , no information is available for the young adults ( 18 - 34 years ) .
the plausible reason for this lack of information comes from the fact that early studies presented results which suggested little or no periodontal destruction before the age of 30 years . taking into consideration the lack of data about periodontal disease among young adults ,
the present study has been designed to assess the periodontal status among the young adults of sebha city .
the study also assesses the relationship of the risk factors , such as age , gender , oral hygiene practices , and smoking with periodontal disease .
a cross - sectional survey was conducted among the young adults aged 18 - 34 years from sebha city , libya .
the city was divided into four zones , and one representative area from each zone was selected .
al - jadeed , al - mahdia , gurda , and sukkara were the four selected areas .
this was carried out to obtain the prevalence of the periodontal disease so as to calculate the sample size for the main study .
the pilot study results revealed that the prevalence of periodontal disease was 56% in al - jadeed .
the sample size was determined by using the formula n = z pq / d .
assuming that the values obtained are z = a point on normal distribution with 95% confidence , p = prevalence of periodontal disease from pilot study , q = 100-p , d = admissible error that is 10% of prevalence .
the survey was conducted at the primary health center ( phc ) in the selected areas .
the medical officer posted at the phc was responsible for enrolling the participants for the study in the respective areas .
young adults who visited the phc for the 1 time and voluntarily wished to participate were recruited for the survey .
schedules were prepared such that the examination of the participant took place on one particular day of the week for one phc center . at first
, the participant was interviewed to collect information as per the pro - forma [ appendix 1 ] and later underwent a clinical examination .
the oral examination was conducted by a single , trained , and calibrated examiner who was assisted by a recording clerk .
10% of the sample was re - examined and a kappa value of 0.8 was obtained .
the codes and criteria of the index were as per the who , oral health survey .
three indicators of periodontal status ; gingival bleeding , calculus , and pockets were assessed .
, 10 index teeth were examined , which were ( 16 , 17 ) , 11 , ( 26 , 27 ) , ( 36 , 37 ) , 31 , and ( 46 , 47 ) .
when two index teeth were considered in a sextant , the tooth with the highest score was recorded . for those below 20 years
, only 6 index teeth were examined , which were 16 , 11 , 26 , 36 , 31 , and 46 .
the overall cpi score of the participant represented the value of the highest recorded code for that individual . during examination , the probe was kept parallel to the long axis of the tooth , the tip was inserted gently into the gingival sulcus or pocket , and the total extent of sulcus or pocket was explored .
the codes were :
 code 0 : teeth are healthycode 1 : bleeding observed , directly or by using a mouth mirror , after probingcode 2 : calculus detected during probing , all the black band on the probe is visiblecode 3 : pocket is 4 - 5 mm ( gingival margin within the black band on the probe)code 4 : pocket is 6 mm or more ( black band on the probe not visible)x : sextant is excluded ( less than 2 teeth present)9 : not recorded .

code 0 : teeth are healthy code 1 : bleeding observed , directly or by using a mouth mirror , after probing code 2 : calculus detected during probing , all the black band on the probe is visible code 3 : pocket is 4 - 5 mm ( gingival margin within the black band on the probe ) code 4 : pocket is 6 mm or more ( black band on the probe not visible ) x : sextant is excluded ( less than 2 teeth present ) all the subjects were well - educated and signed the informed consent form . the ethical board , scientific committee of the faculty of dentistry , sebha university , sebha , libya approved the protocol of the study .
statistical analysis was carried out with the help of a statistical package for social sciences ( spss version 16 ) .
chi - square test and analysis of variance ( anova ) was used to compare between the groups at 5% level of significance .
the variables were age , gender , frequency of tooth brushing , and smoking habit that were compared with the cpi codes .
out of the determined sample size of 1,256 people , the study population comprised of 1,255 individuals , of which 1,006 ( 80.15% ) were females and 249 ( 19.84% ) were males .
the distribution of the sample as per the age and age groups is shown in table 1 .
distribution of the study sample according to the age regarding the oral hygiene practices , overall , 1,118 ( 89.08% ) people reported to have used toothbrush and toothpaste for cleaning and 137 ( 10.91% ) people used other aids , such as finger and siwak . only 50 ( 3.98% ) people were current smokers and all were males , of which maximum ( n = 22 ) people smoked 10 - 20 cigarettes / day .
overall , the cpi analysis showed that a majority of 44.30% ( n = 556 ) were detected with calculus ( cpi code 2 ) followed by 40.63% ( n = 510 ) with shallow pockets ( cpi code 3 ) , 6.29% ( n = 79 ) with bleeding ( cpi code 1 ) , and 4.06% ( n = 51 ) with deep pockets ( cpi code 4 ) .
only 4.7% ( n = 59 ) had healthy periodontium ( cpi code 0 ) .
table 2 shows the distribution of people according to the cpi codes in relation to the different variables considered in the study .
the frequency of tooth brushing and smoking were not significantly related to the cpi codes .
distribution of people according to the community periodontal index cpi codes in relation to the different variables the overall mean cpi score was 2.33 ( 0.84 ) .
mean cpi score of the sample for different ages table 3 shows the mean ( sd ) number of sextants as per the cpi codes in relation to age .
a maximum of 2.45 sextants were healthy among 18 years old , which further gradually decreased as the age advanced . from 19 years onward
mean ( sd ) number of sextants as per the cpi codes in relation to age
the literature search for information regarding the oral health status of the population in sebha resulted in the presence of only one pubmed indexed article by hassan and one document that was an assignment report on the oral health situation in socialist people 's libiyan arab jamahiriya submitted to who geneva by leous .
the study by hassan among patients attending the dental clinic in sebha , libyan arab jamahiriya , reported that the people here , have poor oral hygiene and low level of education .
furthermore , it was found that caries ( 54% ) and periodontal disease ( 41% ) were the main causes for the high frequency of tooth extraction .
the report by leous was a pathfinder study conducted on 849 children and 269 adults from 14 sites of the following localities : tripoli , sebha , benghazi , zwara , ajelat , and kaddah .
the cpitn index was used to assess the periodontal disease , and its results indicate that the periodontal disease was present from a very young age .
very small population in the age group of 20 - 24 years was found to have a healthy periodontium . while drawing a comparison between the population aged 18 years and 20 - 24 years , respective percentage distributions
were observed : 3% and 2% had healthy periodontium , 8% and 0% had bleeding , 66% and 69% had calculus , 25% and 27% had shallow pockets , and 0% and 2% had deep pockets . comparing results of the present study with the results reported by leous indicate the percentages of people with cpi code 0 , 1 , 3 , and 4 to be different , while the prevalence of calculus ( code 2 ) was found to be the highest in both the studies . in the who global oral health data bank for periodontal disease using cpitn index , there was no data available for comparison in the age group 18 - 34 years from emro countries . however , for the ages 18 and 19 years , data from countries belonging to regional office for europe ( euro ) , regional office for western pacific ( wpro ) , regional office for africa ( afro ) , and regional office for south east asia ( searo ) was available and was compared with the present study participants of the same age [ figure 2 ] .
figure 2 presents a view for all the countries , calculus ( code 2 ) was the highest - recorded cpi score except in south africa where the percentage of healthy periodontium was the highest ( 51% ) .
overall , it was observed that the highest prevalence of shallow pockets ( 34% ) was from sebha .
overview of periodontal status from different countries it is widely assumed that symptoms of periodontal diseases escalate with age .
table 3 clearly indicates that the mean number of sextants for lower codes of 0 ( healthy ) and 1 ( bleeding ) was highest among 18 years old , but as the age increased , the mean number of sextants for higher codes of 2 ( calculus ) and 3 ( shallow pockets ) increased .
the presence of shallow pockets , which is an indication of the deterioration of periodontium , was more prevalent in the age group of 25 and above . in the present study
, a significant relation was obtained between cpi codes and gender [ table 2 ] .
although , there was an unequal distribution of males and females , the individual percentage calculation showed that more females had healthy periodontium , bleeding , and calculus as compared to males .
however , the prevalence of shallow and deep pocket was more prevalent in the males .
studies indicate that predominantly males , because of their smoking habit , have shown more susceptibility to periodontal diseases .
though , the smokers in the present study were all males , significant difference in periodontal status was not observed with smoking .
this is a good percentage when compared to other previous studies on libyan and sudanese population , where the percentages were 74.6% and 53% , respectively .
currently , many of the world populations in india , pakistan , several african countries , the arab countries , and most of the muslim world still use miswak .
the study reported that the sudanese regular miswak users had better oral health and lower levels of oral pathogens than adult sudanese who used a modern toothbrush regularly .
however , in the present study , the frequency of tooth brushing was not significantly associated with the cpi codes .
within the limits of the study , it can be concluded that only 4.7% young adults in sebha have healthy periodontium .
the benefits accuring from the control of periodontal diseases and promoting good periodontal health include , improved quality of life , enhanced general well - being and appearance , reduced halitosis , elimination of bleeding gums , reduced potential threat to longevity of teeth , and improved masticatory function .
more importantly , ensuring implementation of preventive procedures amongst young adults could possibly lessen the prevalence of periodontal diseases during their adulthood .
this study is probably , the first of its kind to report data on the young adults in sebha and this information can be utilized for planning a preventive model that will include dental health education and preventive procedures .

Answer:
background : the occurrence of periodontal diseases in humans has been a global problem .
 certain risk factors affect the initiation , progression , and severity of periodontitis .
 the present study has been designed to assess the periodontal status in relation to risk factors such as age , gender , oral hygiene practices , and smoking among the young adults of the sebha city in libya.materials and methods : a cross - sectional study was carried out among 1,255 subjects aged between 18 years and 34 years .
 1,006 ( 80.15% ) subjects were females and 249 ( 19.84% ) subjects were males .
 data was generated by conducting interview and clinical examination .
 the periodontal status was assessed by using community periodontal index of community periodontal index of treatment needs .
 the chi - square test and analysis of variance were used for statistical analysis at 5% level of significance.results:a total of 89.08% reported the use of toothbrush and toothpaste for cleaning and 10.91% used other aids , such as finger and siwak .
 of the 1,255 subjects , 3.98% were current smokers ( all males ) .
 only 4.7% had healthy periodontium ( cpi code 1 ) , while majority of 44.30% were detected with calculus ( cpi code 2 ) .
 nearly 40.63% had shallow pockets ( cpi code 3 ) , 6.29% had bleeding ( cpi code 1 ) , and 4.06% had deep pockets ( cpi code 4 ) .
 the overall mean cpi score was 2.33 ( 0.84 ) .
 age and gender showed a statistically significant difference with the cpi codes.conclusion:the result of this study provides baseline information for planning a preventive program . with preventive procedures
 being implemented at this young age , there is a possibility that the prevalence of periodontal disease will be lesser during adulthood .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
sonographic estimation of fetal weight ( fw ) , especially in late pregnancy is an important guide in obstetric care .
armed with this information informed decisions about delivery can be taken , thereby minimizing perinatal morbidity and mortality .
amniotic fluid cushions the fetus from traumatic forces , cord compression , and pathogens , as well as playing an essential role in fetal lung development . in late pregnancy
, amniotic fluid production is largely dependent on fetal micturition and renal size in the newborn has been shown to bear a significant relationship to birth weight .
it is therefore , reasonable to postulate a relationship between sonographically determined amniotic fluid index ( afi ) and estimated fw .
previous reports have investigated possible relationships between sonographically attained fluid index , and estimated fetal weight ( efw ) including the influence of afi on the accuracy of sonographically efw , among caucasians . however , such studies are rare among africans , especially nigerians .
this study was carried out to find out if any significant relationships exist between afi and efw in a nigerian cohort of healthy pregnant women .
two hundred and fifty - eight low - risk pregnant subjects referred for routine ultrasound scans to the radiology department of the university of benin teaching hospital , nigeria were randomly selected over a 12-month period .
those with unsure dates , diabetes mellitus , and hypertensive disorders were excluded . only those whose menstrual dates
sonography was performed with a 3.5 mhz transducer ( fukuda denshi ; fukuda co ltd , japan ) .
fetal biometrics including biparietal diameter ( bpd ) , using the cavum septum pellucidum as landmark , as depicted in figure 1 ; fetal trunk cross sectional area ( fta ) using the four chamber view of the heart , as illustrated in figure 2 ; and the femur length ( fl ) , with the  hook from the greater trochanter to the distal metaphysis included , as illustrated in figure 3 , were measured .
the fw was automatically estimated by the scanner using a combination of the bpd , fta , and fl , based on the in - built osaka university system 's formula .
ultrasound scan shows how to measure fetal trunk cross sectional area , using the four chamber view of the heart .
sample report 1 shows estimated fetal weight calculated by the osaka university system 's formula .
sample report 2 shows estimated fetal weight calculated by the osaka university system 's formula .
data was entered into a microsoft spreadsheet and analysed using the statistical package for the social sciences ( spss version 16 ) .
measurements were stratified into pairs of afi and efw as follows ; 27 - 29 weeks , 30 - 32 weeks , 33 - 35 weeks , 36 - 38 weeks , and 39 - 41 weeks .
spearman 's correlation was used to test possible relationship between the afi and efw pairs .
the mean age of the subjects was 29.1  4.9 years , and parity ranged from 0 to 7 , with a mean of 1.5 .
the mean maternal weight was 71.4  13.6 kg , and height was 1.6  0.5 m. the number of subjects in each gestational group were distributed as follows ; 64 ( 24.8% ) in the 27 - 29 weeks , 56 ( 21.7% ) in the 30 - 32 weeks ; 48 ( 18.6% ) in the 33 - 35 weeks ; 50 ( 19.4% ) in the 36 - 38 weeks , and 40 ( 15.5% ) in the 39 - 41 weeks ; as outlined in table 1 .
amniotic fluid index and estimated fetal weight values for the gestational age ranges table 1 also shows that the mean afi and efw values for 27 - 29 weeks gestation were 172.1 mm and 1250.19 g respectively ; 30 - 32 weeks were 170.3 mm and 1,648.04 g ; 33 - 35 weeks were 162.3 mm and 2,273.54 g ; 36 - 38 weeks were 144.0 mm and 2,906.12 g ; and 39 - 41 weeks were 125.0 mm and 3,222.65 g. spearman 's correlation values between afi and efw were 0.123 , 0.472 , 0.179 , 0.210 , and 0.221 for 27 - 29 weeks , 30 - 32 weeks , 33 - 35 weeks , 36 - 38 weeks , and 39 - 41 weeks respectively .
there was no significant association between afi and efw for all subdivisions of gestation age , except in the 30 - 32 weeks group ( p < 0.05 ; r = 0.472 ) .
overall , there was no statistically significant relationship between afi and efw ( p > 0.05 ; r = 0.241 ) .
figure 6 shows the scatter plot diagram for all pairs of afi and efw , with r value of 0.241 .
amniotic fluid disorders , oligo - hydramnios , and poly - hydramnios have been associated with intrauterine growth restriction and abnormal fetal growth , but this relationship across the entire range of fws is unclear . however , when used alone , amniotic fluid measurement has been found to perform poorly in predicting fetal distress , fetal growth restriction or low apgar scores , among others .
polyhydramnios and oligohydramnios could overestimate or underestimate sonographic fw assessment . while there are reports of afi measurements and ultrasound efws , as separate parameters , both in the nigerian and international literature,[810 ] there are few reports that assessed the possible relationship between afi and estimated weight , for both normal ( non - diabetic ) and diabetic pregnancies .
this study found a decrease in mean afi values from 172.1 mm in early third trimester ( 27 - 29 weeks ) , to a value of 144.0 mm at 36 - 38 weeks , before a sharp drop to 125.0 mm at 39 - 40 weeks , as observed in previous studies .
as expected increase in fw was noticed throughout pregnancy , but there was no significant association between afi and efw when all the afi and efw pairs were considered ( p > 0.05 ; r = 0.241 ) . only the afi and efw pair for gestation age 30 - 32 weeks showed any significant relationship ; ( p < 0.05 ) .
this lack of significant relationship between afi and efw across all gestational age strata is supported by the works of perni et al . , and owen et al .
possible reasons adduced for this are that swallowing and urinating mechanisms , rather than fetal size , are more involved in regulation of amniotic fluid volume .
the implication of this is that fetal size may not need to be considered in variations of amniotic fluid volume across the gestational ages .
it is interesting to note that kofinas and kofinas in 2012 , found a significant relationship between afi and efw for both diabetic and non - diabetic pregnancies .
while no explanation was offered for the former , it was postulated that fetuses of diabetic pregnancies spend more time breathing than swallowing ; since swallowing and breathing are mutually exclusive , the fetuses do not swallow as much amniotic fluid as expected ; thus in diabetic pregnancies , it may be necessary to consider fetal size when interpreting amniotic fluid variations across gestational ages .
this present report on relationship between amniotic fluid and estimated fetal weight is probably the first among pregnant women in nigeria and therefore , raises the need for more studies on the subject , especially with larger sample sizes .
it has nonetheless supported the majority of the views of similar works in the foreign literature that reported the non - dependence of amniotic fluid measurements on ultrasound estimated fetal size .
this study has produced a range of values of afi and efw among nigerian africans . however , no significant relationship exists between these parameters .
the probable implication of this is neither parameter merits consideration when variations in the other are considered .

Answer:
introduction : fetal weight ( fw ) estimation in late pregnancy is an important guide in obstetric care .
 amniotic fluid protects the fetus against traumatic and infective insults .
 there possibly exists a relationship between fw and amniotic fluid index ( afi ) that can be estimated by ultrasonography.materials and methods : two hundred and fifty - eight low - risk pregnancies were prospectively studied by means of ultrasound over a 12-month period .
 fw was estimated using a combination of fetal parameters ; bi - parietal diameter , fetal trunk cross sectional area , and femur length .
 afi was assessed using the 4-quadrant method .
 spearman 's correlation was used to test possible relationship between amniotic fluid indices and estimated fw pairs .
 the level of statistical significance was set at p  0.05.results:the mean af1 and estimated fetal weight ( efw ) pairs were as follows : at 27 - 29 weeks the values were 172.1 mm and 1,250.2 g ; at 30 - 32 weeks af1 and efw values were 170.3 mm and 1,648.0 g ; at 33 - 35 weeks values were 162.3 mm and 2,273.5 g ; at 36 - 38 weeks values were 144.09 mm and 2,906.1 g ; at 39 - 40 weeks af1 and efw values were 125.0 mm and 3,222.6 g. overall , there was no statistically significant relationship between afi and efw ( p > 0.05 ; r = 0.241).conclusion : while fw calculations and amniotic index showed variations in value in late pregnancy , there does not appear to be a linear relationship between ultrasound estimate of fw and amniotic index .
 the implication of this is that fetal size need not be taken into cognizance when alterations in amniotic fluid values are noted .


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:

 disporopsis pernyi ( hua ) diels , which belongs to disporopsis genus of liliaceae family , mainly grows in south asia such as vietnam , laos , thailand , and yangtze river basin of china .
it was a well - known traditional chinese medicine which has been widely used for the treatment of abnormal sweating , chronic cough , women postpartum weakness and irregular menstrual cycle , and so forth .
the medical value of disporopsis genus plants has not got much attention until the beginning of 21st century .
the roots of the plant are rich in bioactive substances which are possible to have considerable medicinal value and can be used for hypertension cough , inflammation , and tumor .
study suggests that a total of 4 polyphenolic compounds are found in extract including rutin , luteolin , quercetin , and betulinic acid , and the phenolic compounds contribute significantly to the antioxidant and antimicrobial activities [ 2 , 3 ] .
rutin has both antihypertensive effect and antidiabetes effect [ 4 , 5 ] . luteolin which has anti - inflammatory , antibiosis , and anticancer properties has been used for relieving cough and eliminating phlegm . in addition , it has potential anti - hiv effect [ 6 , 7 ] .
quercetin can be used for relieving cough and eliminating phlegm and for hypertension and hyperlipemia ; also , it has neuroprotective and antiproliferative activities [ 8 , 9 ] .
acid can kill human melanoma cell without hurting healthy cell and inhibit the hiv-1 infection .
additionally , recent study shows that it also has the inhibition effects of cerebroma and leukocythemia [ 10 , 11 ] .
the four compounds are major bioactive constitutes in the extract of disporopsis pernyi ( hua ) diels roots .
so far , there is no report on the content of the 4 polyphenolic compounds in disporopsis pernyi ( hua ) diels .
uplc is a simple and quick tool for the quantitative determination of the bioactive constituents in pharmaceutical industry [ 1214 ] . as rutin , luteolin , quercetin , and betulinic acid
the hplc - grade methanol and acetonitrile used were purchased from caledon ( canada ) and formic acid was obtained from dima company ( beijing , china ) .
the rutin , luteolin , quercetin , and betulinic acid were purchased from the national institute for the control of pharmaceutical and biological products in china .
the purity of the standard compounds was 98% ; their chemical structures are shown in figure 1 .
disporopsis pernyi ( hua ) diels were collected from songtao which is in guizhou province of china .
standard stock solutions of rutin , luteolin , quercetin , and betulinic acid were dissolved in methanol , at concentration of 1.0  mg / ml . all standard solutions were filtered through 0.22  m syringe filter . the extraction was carried out using 5.0  g of powdered roots . it was dissolved in 50  ml of 70% ethanol solution and back - flow for 60  min .
after filter and rotary evaporation to no ethanol smell , 50  ml acetic ether was added and extraction was done three times .
the extract and washing liquid were combined and filtered and then evaporated to dryness under reduced pressure in a rotary evaporator .
the dried extract was dissolved in methanol and diluted to a 5  ml volumetric flask .
the hplc system used was a shimadzu nexera x2 uplc ( kyoto , japan ) chromatograph equipped with a solvent delivery unit ( lc-30ad ) , an autosampler ( sil-30ac ) , a column oven ( cto-20a ) , a degasser ( dgu-20a5r ) , and a photodiode array detector ( spd - m20a ) .
separation was conducted on a shim - pack xr - ods column ( 2.0  75  mm , 1.6  m ; shimadzu cooperation , japan ) .
the column temperature was set at 30c . the mobile phase consisted of water containing 0.1% formic acid ( a ) and acetonitrile ( b ) .
the composition of the mobile phase was 5% ( b ) for 02  min , 5%10% ( b ) for 24.5  min , 10%40% ( b ) for 4.511  min , 40%60% ( b ) for 1113  min , 60%70% ( b ) for 13 - 14  min , 70%80% ( b ) for 1416  min , 80%90% ( b ) for 16 - 17  min , 90% ( b ) for 1720  min , and it was held for 3  min and then reequilibrated to 5% ( b ) until the end of the analysis .
the flow rate was 0.2  ml / min and the injection volume was 5  l .
the detection wavelengths of all standards and samples were in the uv at 210 , 254 , and 280  nm .
the 4 standard compounds were accurately weighed and dissolved in methanol to prepare stock solutions at a concentration of 1.0  mg / ml . stock solutions of the compounds were serially diluted to construct calibration curves .
the diluted concentrations of compounds were plotted against the peak area on the calibration curves and the linearity was measured from the correlation coefficient .
blank samples were analyzed in triplicate and the area of the noise peak was calculated as the response .
the lod and loq were calculated as lod = 3.3  sd / s and loq = 10  sd / s , where sd is the standard deviation of the response and s is the slope of the calibration curve .
the precision was calculated by analyzing sample extracts containing low and high concentrations of the compounds .
the precision was represented by the relative standard deviation ( rsd ) , which was calculated using the equation rsd = ( standard deviation / mean )  100 .
the precision was measured three times in a single day ( intraday precision ) and over three consecutive days ( interday precision ) .
the recovery was calculated as follows : recovery ( % ) = ( ( detected concentration  initial concentration)/spiked concentration )  100 .
we used pda detector in this experiment , which could select each wavelength of chromatogram . in our study , we took into account the question that most of the components we studied also have good absorption at wavelength of 350  nm and 370  nm [ 15 , 17 ] . by comparing the resolution and response at different wavelength , the results showed that the resolution and response of the four components at 350  nm and 370  nm are not as good as the wavelengths 210 , 254 , and 280  nm we chose . also , we chose 210  nm to detect betulinic acid for its good response .
combined with the literature reports , methanol - water , acetonitrile - water , and methanol - acetonitrile - water were examined as mobile phase as well as the type ( formic acid and glacial acetic acid ) and concentration ( 0.01% , 0.05% , and 0.1% ) of the acid . a shim - pack xr - ods column was employed for the simultaneous determination of the 4 compounds , as it has been the most frequently used technique in the chemical analysis of herbal medicines by uplc .
peak resolution and shape of the compounds were considered better indicators when 0.1% formic acid was used as a modifier .
taking peak shape , degree of separation , the symmetrical factor , and other factors into consideration , acetonitrile-0.1% formic acid water solution was determined as gradient elution process .
the linearity of the calibration curve was measured by the correlation coefficient ( r ) , which ranged in value from 0.9992 to 0.9997 for each compound .
the lod and loq were 0.1370.264  g / ml and 0.4560.881  g / ml , respectively ( table 1 ) .
the intra- and interday precision , which were represented by the rsd values , were rsd < 2.0% .
the recoveries of the 4 compounds were in the range 96.2%102.6% , with rsd < 2.0% ( table 2 ) .
the results indicate that the developed analytical method was accurate and precise for the analysis of the 4 compounds in disporopsis pernyi ( hua ) diels .
the method we developed was applied to determine the 4 compounds in disporopsis pernyi ( hua ) diels successfully .
the calculated contents of the four compounds were 5.63  g / g for rutin , 2.51  g / g for luteolin , 3.87  g / g for quercetin , and 2.41  g / g for betulinic acid .
the uplc method mentioned here represented an excellent technique for simultaneous determination of rutin , luteolin , quercetin , and betulinic acid in the extract of disporopsis pernyi ( hua ) diels roots , with good sensitivity , precision , and reproducibility .
the method gives a good resolution among the four components with the analysis time ( 25  min ) .
furthermore , the method can be used as quality control of polyphenolic compounds in disporopsis pernyi ( hua ) diels roots and will play a reference role on the determination of polyphenolic compounds in other medicinal plants or pharmaceutical preparations .

Answer:
disporopsis pernyi ( hua ) diels , which belongs to genus disporopsis , has been widely used for the treatment of abnormal sweating , chronic cough , and so forth .
 an ultra - performance liquid chromatography ( uplc ) analysis was developed for the determination of rutin , luteolin , quercetin , and betulinic acid in disporopsis pernyi ( hua ) diels roots .
 uplc analysis was conducted by using a shim - pack xr - ods column with gradient elution with the mobile phase of acetonitrile and water containing 0.1% formic acid and with a flow rate of 0.2  ml / min , detected at 210 , 254 , and 280  nm .
 the method was precise , with relative standard deviation < 2.0% .
 the recoveries for the four components in disporopsis pernyi ( hua ) diels were between 98.5 and 100.9% .
 the average contents of rutin , luteolin , quercetin , and betulinic acid in roots were 5.63 , 2.51 , 3.87 , and 2.41  g / g , respectively .
 the method was accurate and reproducible and it can provide a quantitative basis for quality control of disporopsis pernyi ( hua ) diels .


Question:
You will be shown the title of a chemistry paper, together with sections excerpted from the body of the paper. The paper sections may include HTML tags like `<p>` and `</p>`; please ignore these. Your task is to write an abstract for the paper. Your response should include the abstract and no other text.

Title:
Synthesis of 15-methylene-eburnamonine from (+)-vincamine, evaluation of anticancer activity, and investigation of mechanism of action by quantitative NMR

Paper sections:

Natural products have long been a source of inspiration for drug discovery, especially in the area of cancer research.1 Indeed, from the period of 1981 to 2010, 75% of all FDA-approved new chemical entities (NCE) for treatment of cancer were either derived from or inspired by natural products.1 One of the richest sources of naturally derived chemotherapies is the Madagascar periwinkle (Catharanthus roseus) which produces the cytotoxic vinca alkaloids, vinblastine and vincristine.2,3 Vindesine and vinorelbine are two semi-synthetic drugs that are built from the naturally occurring scaffolds. Also, the Madagascar periwinkle is a source of the eburnamine-vincamine alkaloids, vincamine (1) and (−)-eburnamonine (2) (Fig. 1).4 These alkaloids are unique because they display their biological activity in the CNS. Another important member of this class of alkaloid is vinpocetine (3) which is a synthetic derivative of 1.4,5

Although vincamine 1 is generally considered to be the mother compound of these cerebrally active alkaloids, eburnamonine 2 has been shown to improve cerebrovascular disorders in patients.4,6 Moreover, in studies in canines, it can enhance both oxygen and glucose consumption in the brain as well as improve the brain's oxygen supply by increasing vertebral blood flow.4 Additional studies in rats have revealed that eburnamonine 2 can help alleviate learning and memory impairments in different experimental models of amnesia7 and can improve cerebrovascular function.8 Even though the mechanism of action has not been fully elucidated, it has been established that 2 has a relatively high affinity for human muscarinic receptors.9,10

Due to the array of biological activities displayed by these alkaloids, they have been a target of synthetic and medicinal chemists. For example, a total synthesis of (−)-eburnamonine 2 and of (+)-epi-eburnamonine was accomplished by Wee.11 The most efficient total synthesis of racemic eburnamonine was published by Ghosh with an excellent overall yield of 35%.12 Eburnamonine (2) can also be accessed directly from vincamine (1) using a one-pot two-step procedure13 which was later optimized.14 Analogues of eburnamonine have been prepared by hydroxylation,15,16 trifluoromethylation,17 and nitration,16 but biological evaluations of these derivatives have not been reported. Amide derivatives of 2 at the C11-position have been synthesized and were investigated as protective agents against tin-induced brain edema.18 More recently, vinpocetine analogues were prepared and examined as potential antioxidants and cognitive enhancing agents.5 In 2011, Colby and co-workers synthesized 15-methylene-eburnamonine (4) by using an α-methylenation strategy that is promoted by the release of trifluoroacetate (Scheme 1).19 Analogue 4 displays antiproliferative activity in HL-60 (human leukemia) and cytotoxicity in MDA-MB-231 (breast cancer) cells (LC50 = 14.1 μM); however, the parent natural product 2 is nearly inactive in both cell lines. Even though the conversion of eburnamonine 2 into 15-methylene-eburnamonine 4 was accomplished in two steps, the yield was quite low (i.e., 28%). The steric congestion at the C16 position of 2 is apparent in its X-ray structure20 and prevents the installation of the α-methylene group using many other standard protocols; therefore the trifluoroacetate-release olefination approach was required to access the target 4. In order to conduct a more extensive biological evaluation of 4 in malignant cells as well as define its mechanism of action, an improved synthesis was clearly needed. Herein, we describe an efficient and scalable synthesis of 4 from 1 that enabled an investigation of its antiproliferative in additional cell lines and characterization of its mechanism of action by quantitative NMR.

Even though the target 4 was originally synthesized from eburnamonine 2, a more plentiful starting material was required to enable the production of larger quantities of 4; therefore, the aforementioned one-pot two-step synthesis from vincamine 1 was selected (Scheme 2).13 Accordingly, the alkaloid 1 was reduced with NaBH4 and BF3·OEt2 at 0 °C and then treated with a mixture of aqueous H2O2 and NaOH. Following purification, gram quantities of eburnamonine 2 were accessed. Next, 2 was transformed into oxime 5 (as a pair of rotamers) using t-BuOK and t-BuONO by the literature protocol.21 Acid-promoted hydrolysis with 15% aqueous HCl at 110 °C provided the known dione 6 in 64% yield (from 2).21 All of the new and previously reported compounds were characterized by 1H NMR, 13C NMR, IR, HRMS, and optical rotation.

Studies to convert the dione 6 into the target 4 were undertaken using a series of Wittig reactions that are listed in Table 1. Excess quantities of t-BuOK and PPh3CH3I were used in all of the reactions to promote this olefination process, but regardless of temperature, base, or solvent, only unreacted starting material was isolated. These results were disappointing because high temperatures can aid in the olefination of sterically hindered carbonyl groups using Wittig reactions. Next, titanium methylene complexes were screened,22 and only the highly reactive Tebbe reagent could overcome this critical issue of steric congestion at the C16 position and produce 4 in an optimized 16% yield.

A Peterson-type methylenation was then selected and trimethylsilylmethyl lithium was reacted with the ketone 6 to give the stable tertiary alcohol 7 (Scheme 3).23 Next, protodesilylation/elimination was attempted using many conditions, but this approach was not successful. For example, the alcohol 7 was completely inert to BF3·OEt2 and merely desilylated following exposure to TFA Therefore, the sterically encumbered tertiary alcohol 7 was trifluoroacetylated to 8 with TFAA and TMSOTf,24 which were required over the less-reactive, traditional mixture of TFAA with DMAP. The intermediate trifluoroacetyl ester 8 was treated with TASF to liberate the silyl group and eliminate trifluoroacetate; the target 15-methylene-eburnamonine 4 was finally accessed. The four-step sequence from the oxime 5 provides the product 4 in 59% yield.25 Although the highest yields in the final step were obtained with TASF, this reagent was replaced with CsF in DMF on a larger scale with only a modest decrease of isolated yields. The overall yield from vincamine 1 is 40%. Accordingly, we have synthesized up to 115 mg of 15-methylene-eburnamoine 4 for biological and mechanistic evaluations.

15-Methylene-eburnamonine 4 and eburnamonine 2 were tested side-by-side for cytotoxic activity in four additional cell lines: LNCaP (prostate cancer), RPMI-8226 (multiple myeloma), U266 (multiple myeloma), and KMS-12BM (multiple myeloma) cells (Table 2).26 Our rationale for choosing these additional cell lines is to compare prostate cancer cells to breast cancer cells and apply our prior discovery that enone-based anti-leukemic agents are also active against multiple myeloma cell lines.27 Agent 4 displays micromolar activity against the four cell lines and the natural product 2 is nearly inactive even at the high dose of 100 μM. Compound 4 displays higher cytotoxicity in prostate and myeloma cells compared to MDA-MB-231 (breast cancer) cells.19 Its most potent effects were LC50 = 4.3 μM (U266) and LC50 = 4.0 μM (KMS-12BM), and these low micromolar activities were an excellent validation of the aforementioned synthetic studies. The cell viability curves for four cancer cell lines are depicted in Figure 2 and present additional perspective on the side-by-side comparisons between 2 and 4. These viability curves, along with the previously published curves in MDA-MB-231 cells,19 display the repeated difference between the two agents across the five cells in that only compound 4 eliminates cancer cells in the low micromolar range. An additional antiproliferative study was conducted with agent 4 in an immortalized non-cancerous cell line to examine its potential selectivity for cancer cells. Indeed, highly selective killing of cancer cells has been demonstrated by the natural product, piperlongumine, which bears a similar α,β-unsaturated amide.28 The LC50 value of 4 in FnMSC cells, an immortalized mesenchymal stem cell line derived from the bone marrow, is 16.71 μM.29 The direct comparison of this data to cancer cells is to the LC50 value of 4.0 μM in KMS-12BM cells, and these data demonstrate decrease in potency in the non-cancerous cells compared to cancer cells.

The incorporation of an α-methylene group on eburnamonine 2 (thus forming 4) clearly imparted cytotoxic activity against the cancer cell lines. It is well known that α,β-unsaturated carbonyl groups may produce cytotoxic effects following a Michael addition from nucleophiles such as biological thiols.30 To define the structure–activity relationship of the enone of 4, the α,β-unsaturation was reduced with Pd/C and H2 and analogue 9 was produced in 85% yield as a single diastereomer (Fig. 3).31 The axial assignment of the stereochemical configuration at the C15-site (eburnamonine numbering, see Fig. 1) was accomplished after acquisition of COSY and NOESY. On derivative 9, the proton at the C15 position is a quartet (J = 7.0 Hz) at 2.83 ppm and displays a NOESY crosspeak with the axial methine proton at the C3 position. This proton (see also Scheme 1) is a singlet at 4.16 ppm and exhibits a key NOESY crosspeak with the axial C21 methyl group (t, J = 7.5 Hz) at 0.98 ppm. These data support the axial assignment, because each is on the same face of the molecule. Next, a comparison of the cytotoxic effects of 9 and 4 in MDA-MB-231 cells demonstrates the expected loss of biological activity from removing the unsaturation at C15-position (Fig. 3B). These data validate the critical nature of the enone and this important structure–activity relationship.

To establish the reactivity of the enone towards thiol-based nucleophiles,32 quantitative NMR studies were conducted.30,33 Quantitative NMR is a powerful analytical tool, and although the utility of NMR for structure determination is well established, its potential application in quantitation has not been fully appreciated in bio-organic and medicinal chemistry. Specifically, almost all molecules readily generate unique NMR signals, and the amplitude (integration) of NMR signals can be acquired proportional to the concentration. This technique eliminates the requirement of an internal standard to calibrate concentration. Knowing the exact concentration of a biologically active molecule and calculating the change in concentration in relationship to time provides valuable kinetic data. This point is fundamental in the reactivity of enones towards thiol-based nucleophiles, because the structure of the enone and the nature of the solvent can cause substantial differences in reactivity.32 Dithiothreitol (DTT) was chosen as a representative thiol for investigation with 15-methylene-eburanmonine 4 without any deuterated solvent.34 Accordingly, in an NMR tube, DTT (10 equiv) was added in one portion to a solution of 4 in 80% PBS buffer (pH 8.0) and 20% ethanol. The NMR sample was immediately placed in the spectrometer and spectra were acquired at intervals of 2, 8, 18, and 80 min. (Fig. 4). The 1H NMR peaks corresponding to the methylene groups disappeared after the addition of DTT; these data indicate that the thiol was adding into the enone. The changes in the concentration of 4 were simultaneously quantified by NMR at each time interval using our previously published no-D NMR methods (Fig. 4B).33,35 At t = 0 min, the concentration of 4 was 400 μM. Two minutes after treatment with DTT, the concentration of 4 decreased to 330 μM. After 18 min had elapsed, the concentration of 4 was 220 μM, and after 80 min, the compound was not detected (Fig. 4C).

These studies demonstrate the utility of installing an exocyclic enone into the structure of a natural product to impart anticancer activity as well as chemical reactivity toward nucleophilic thiols. The application of these structure–activity data is a key one, because biological activity (i.e., micromolar levels) can be efficiently realized. Also, a modified Peterson olefination was accomplished through the facile release of trifluoroacetate to create the requisite enone in the presence of substantial steric hindrance. Moreover, exploiting the release of trifluoroacetate enabled this selective modification to the structure of the natural product, eburnamonine. Lastly, the robustness and simplicity of quantitative analysis by NMR, which can be done readily without the use of deuterated solvents, were demonstrated by in situ monitoring of the consumption of reactant and formation of product. This NMR approach can gather mechanistic and kinetic data simultaneously, and presents a unique opportunity to examine complex systems at the interface of chemistry and biology.

Answer: The biological role of installing a critical exocyclic enone into the structure of the alkaloid, (\xe2\x88\x92)-eburnamonine, and characterization of the new chemical reactivity by quantitative NMR without using deuterated solvents are described. This selective modification to a natural product imparts potent anticancer activity as well as bestows chemical reactivity toward nucleophilic thiols, which was measured by quantitative NMR. The synthetic strategy provides an overall conversion of 40%. In the key synthetic step, a modified Peterson olefination was accomplished through the facile release of trifluoroacetate to create the requisite enone in the presence of substantial steric hindrance.


Question:
You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
from msm who attended the amsterdam municipal health service sti outpatient clinic in 2000 and 2001 , randomly selected stored specimens of c. trachomatis dna  positive ( as assessed by ligase chain reaction , abbott laboratories , chicago , il , usa ) rectal samples were tested for the c. trachomatis variant by real - time pcr ( 6 ) . from 2002 to 2005 , msm with symptomatic proctitis ( i.e. , purulent discharge , rectal ulceration , bleeding , or edematous mucosa ) and msm without symptoms were included . from the san francisco region , 51 lgv  positive isolates from symptomatic msm were analyzed ( 7 ) .
the isolates were collected in medical clinics ( e.g. , ambulatory care , emergency room , screening , acute care ) from 1979 to 1985 ( table ) .
lgv was assessed at the time of collection , according to phenotypic properties observed during cell culture .
although the growth characteristics of lgv serovars can be distinguished from serovars d  k , cell culture for c. trachomatis is no longer available in most clinical settings . * in 2002 and 2003 , 45 lgv l2b variants of 109 isolates have been described in detail ( 5 ) . c. trachomatis serovar typing was performed as described previously ( 5 ) .
briefly , amplification of the ompa gene ( 1.1 kb ) was performed in a nested pcr format .
the ompa nucleotide sequences were subsequently analyzed by automated dna sequencing on an abi 310 sequencer ( pe biosystems , foster city , ca , usa ) .
the sequences obtained from c. trachomatis  infected msm in 2000 and 2001 in amsterdam and from msm in san francisco were compared to the recently identified l2b variant to determine if the strain was present earlier .
the table presents the results of this analysis . in the amsterdam c. trachomatis dna  positive rectal samples ,
lgv strains were detected by real - time pcr in 2 of 67 samples in 2000 and in 4 of 28 samples in 2001 .
sequencing showed that in all 6 lgv strain  positive samples , the l2b variant was present .
also in 2002 and 2003 , 109 l2b - positive samples of 403 c. trachomatis dna  positive rectal samples were identified , of which 45 were strain l2b , and these have been described in a previous publication ( 5 ) .
all 51 san francisco specimens ( from 51 patients ) were positive for lgv variants by real - time pcr . by sequencing variable segment 2 of the ompa gene ( vs-2 )
, we identified 15 as serovar l1 , 18 as serovar l2 prototype , and 18 as the l2b variant .
we sequenced the complete ompa gene of 5 of these 18 l2b variants that originated in san francisco ; all were identical to the recently described l2b variant circulating in amsterdam .
four nucleotide changes were found when compared to reference serovars l2 , l2a , and the variant l2  , including 1 change that encoded the previously undescribed change at amino acid 162 , aatagt ( 5 ) .
the l2b lgv variant identified as the cause of all the lgv proctitis in the recent outbreak among msm in amsterdam appears to have been circulating in amsterdam in 2000 .
moreover , we showed that this l2b variant was present in the 1980s in san francisco with exactly the same mutations in the complete ompa gene .
however , since we only sequenced the ompa gene , and although the sequence was identical in old and new l2b strains , we can not exclude the possibility that it could involve different strains of c. trachomatis that differ in other parts of the genome , although this is unlikely .
since lgv causes potentially severe infections with possibly irreversible sequelae if adequate treatment is not begun promptly , early and accurate diagnosis is essential .
sequence - based nucleic - acid tests that can discriminate between lgv serovars and less invasive c. trachomatis species can help detect cases and prevent further transmission of lgv . in conclusion , our results suggest that we are dealing with the same lgv variant > 25 years later , and the current lgv outbreak in industrialized countries has most likely been a slowly evolving epidemic with an organism that has gone unnoticed in the community for many years and is now being detected by new technologies .
the numbers detected in 2005 in amsterdam suggest that a considerable reservoir exists , which emphasizes the need for ongoing public health awareness .

Answer:
we traced the chlamydia trachomatis l2b variant in amsterdam and san francisco .
 all recent lymphogranuloma venereum cases in amsterdam were caused by the l2b variant .
 this variant was also present in the 1980s in san francisco .
 thus , the current " outbreak " is most likely a slowly evolving epidemic .