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:
malignant glaucoma , or aqueous misdirection syndrome , is a condition characterized by sudden intraocular pressure ( iop ) elevation , and it is usually unilateral and induced by ocular surgical intervention or by medical therapy . here , we report a case of simultaneous bilateral malignant glaucoma in a young patient with no history of any ocular diseases .
a case of a 24-year - old female with no apparent previous history of ocular medical or surgical conditions was referred to our hospital because of recent bilateral iop elevation associated with a severe drop in vision and shallow anterior chamber with no posterior segment anomalies detected by ocular ultrasound in both eyes .
yttrium aluminum garnet ( yag ) laser iridotomy dropped the iop only temporarily and the patient received topical atropine treatment with combined trabeculectomy and anterior vitrectomy .
in this case , the patient had a typical presentation of bilateral malignant glaucoma and her iop dropped only temporarily following laser iridotomy to rise again shortly thereafter .
also , deepening of the anterior chamber and iop decrease after topical atropine was very supportive of the diagnosis of malignant glaucoma .
this is a very rare case of bilateral malignant glaucoma in a young adult without any prior eye conditions ; only one similar case has been reported in the literature .
we propose our own theory regarding this simultaneous occurrence of the pathology based on previously published studies about the presence of communication between the two eyes along the cerebrospinal fluid pathways .
malignant glaucoma , or aqueous misdirection syndrome , was first described by von graefe in 1869 as an aggressive form of postoperative glaucoma that is resistant to treatment and can result in blindness.1 this entity is characterized by intraocular pressure ( iop ) elevation , with shallowing to complete flattening of the anterior chamber ( ac ) in the presence of a patent peripheral iridectomy and in the absence of posterior segment anomalies , particularly suprachoroidal hemorrhage.2 malignant glaucoma is thought to occur in anatomically predisposed eyes,2 with one of the proposing mechanisms being posterior misdirection of the aqueous humor within or behind the vitreous substance .
this produces a continuous expansion of the vitreous cavity and increased posterior segment pressure , leading to anterior displacement of the lens  iris diaphragm in phakic and pseudophakic eyes , or forward displacement of the anterior hyaloid face in aphakic eyes.3 this generates a vicious cycle , in that the higher the pressure in the posterior segment , the more firmly the lens is held forward .
the iop is classically markedly increased , but it may also be normal.4 malignant glaucoma has been reported in different situations , such as following cataract surgery , laser iridotomy , neodymium : yttrium aluminum garnet ( nd : yag ) cyclophotocoagulation or sclerotomy ; following glaucoma drainage device implantation , viscoelastic use , intravitreal injection of triamcinolone acetonide ; with aspergillus flavus intraocular infection ; and with the ingestion of topiramate or sulfa drugs.5,6 only a few cases of isolated malignant glaucoma have been reported in eyes without any antecedent eye diseases or surgery , and only one case of bilateral simultaneous idiopathic malignant glaucoma has already been reported in the literature.7 here , we report a case of spontaneous , simultaneous , bilateral malignant glaucoma in a young female with no systemic or eye diseases and no prior medical or surgical eye treatments .
we also propose a postulated mechanism that might explain the simultaneous bilaterality of this case .
the patient is a 24-year - old female who was referred to our eye center in mediclinic dubai mall , dubai , united arab emirates , because of recent bilateral iop elevation with a severe drop in vision .
she had been hospitalized elsewhere 1 week earlier because of severe bilateral frontal headache , nausea , and vomiting .
blood tests and brain magnetic resonance imaging ( mri ) were performed and revealed no abnormalities . during her stay
after 5 days in hospital , the patient complained of loss of vision in the right eye , and after approximately 6 hours , also in the left .
the ophthalmology consultant suspected bilateral acute angle - closure glaucoma as a possible cause for the severe bilateral loss of vision .
goldmann applanation pressure was > 60 mmhg in both eyes ; the patient presented with severely miotic pupils and flat chambers , with almost iridocorneal touch centrally , cloudy corneas , and severe bulbar conjunctival injection .
the patient s past history was negative for any medical or surgical diseases and her eye history was also negative .
of note , a routine eye examination had been performed a few months earlier and was reported to be normal .
initial management at our center consisted of multiple topical antiglaucoma medications and intravenous acetazolamide ( 500 mg ) .
ultimately , we managed to perform bilateral nd : yag laser peripheral iridotomy despite the corneal clouding .
after the peripheral iridotomy , the iop dropped in both eyes to around 45 mmhg , but it rose back to its original level after less than half an hour .
the diagnosis of bilateral malignant glaucoma was raised and the patient was admitted to hospital for surgical management .
topical atropine 1% drops and intravenous mannitol ( 1 g / kg of body weight ) were started , and the patient was put under continuous monitoring . in less than 2 hours ,
the acs started to deepen in both eyes , with partial clearing of the corneas .
the iop dropped again to 45 mmhg in both eyes . at that stage , the possibility of bilateral malignant glaucoma as a diagnosis was more likely .
the next day , the patient was scheduled for trabeculectomy with mitomycin - c ( 0.02% for 2 minutes ) combined with pars plana vitrectomy .
informed consent was obtained from the patient prior to surgery . in the meantime , overnight treatment with topical atropine and antiglaucoma medications was continued , along with intravenous acetazolamide .
a second dose of intravenous mannitol was repeated 1 hour before the planned surgery . at the time of surgery ,
surgery was performed in the right eye as planned , and the same procedure was carried out in the left eye 1 day later . in brief , the surgical procedure was performed in both eyes as follows : a limbus - based conjunctival flap was performed , followed by topical 0.2% mitomycin - c application for 2 minutes ; prior to the dissection of a 33 mm half - thickness trabeculectomy flap , one - port limited core vitrectomy was performed through a pars plana approach 4 mm from the limbus .
after completion of the vitrectomy , the trabeculectomy was completed by entering the ac through a small sclerotomy opening using a super blade .
the trabeculectomy flap was sutured back using two 10 - 0 nylon titrated sutures , and the conjunctiva was closed using running 8 - 0 vicryl ( johnson & johnson , new brunswick , nj , usa ) .
postoperatively , the patient was put on a topical combination of tobramycin ( 3 mg / ml ) and dexamethasone ( 1 mg / ml ) , and atropine was continued once a day for 2 weeks .
both eyes had well - formed superior blebs and , surprisingly , visual acuity returned to 20/20 without correction , and there was no optic nerve ( on ) damage in either eye .
the iop remained < 18 mmhg all throughout the postoperative follow - up period , which extended for more than 1 year , with both eyes maintaining deep chambers and reactive pupils .
the study was approved by the review board / ethics committee of the beirut eye specialist hospital , beirut , lebanon .
the main features of malignant glaucoma ( or aqueous misdirection syndrome ) include : increased iop ; the presence of shallowing to complete flattening of the ac ; the absence of posterior segment anomalies  particularly suprachoroidal hemorrhage ; no response to peripheral iridectomy ; and adequate response to topical atropine.2,7 malignant glaucoma is difficult to treat and characteristically progresses to blindness.2 in our case , the patient had a typical presentation of malignant glaucoma and the iop dropped only temporarily after laser iridotomy , to rise again shortly thereafter . also , deepening of the ac and iop decrease after topical atropine was very supportive of the diagnosis of malignant glaucoma .
although malignant glaucoma typically occurs in predisposed eyes , especially among those subjected to surgical or medical therapy , only a few cases have been reported where isolated malignant glaucoma occurs without a previous history of any kind of treatment and , to the best of our knowledge , only one case of bilateral simultaneous idiopathic malignant glaucoma has been reported in the absence of any history of previous systemic or eye diseases.7 as such , our case is considered as the second report of bilateral idiopathic malignant glaucoma .
the rare phenomenon of malignant glaucoma occurring simultaneously in both eyes of young patients who do not have any predisposing factors is highly unusual and warrants exploration .
malignant glaucoma is thought to occur in anatomically predisposed eyes,2 with one of the proposed mechanisms being posterior misdirection of the aqueous humor within or behind the vitreous body , which leads to anterior displacement of the iris  lens diaphragm and anterior hyaloid face.3 in our case , the occurrence of malignant glaucoma in one eye ( most probably the right eye first , as deduced from the patient s own story ) was in an anatomically predisposed eye , and the aqueous entrapped behind the vitreous established a pressure gradient between the on head and the cerebrospinal fluid ( csf ) in the subarachnoid space ( sas ) of the on .
this pressure gradient encouraged fluid movement toward the sas of the on and subsequently to the sas of the brain .
migration of fluid to the sas of the controlateral on could occur directly through the optic chiasm , or it could be mediated by the elevated csf pressure within the sas of the central nervous system through the phenomenon of bidirectionality of csf flow.8 this proposed mechanism of aqueous humor migration from the vitreous cavity to the on and csf of the brain is also supported by the observation of silicone oil ( so ) migration from the vitreous cavity to the on and to the brain in vitrectomized eyes.9,10 also , espinosa et al11 reported the migration of so into the on of the contralateral eye causing optic neuritis .
this migration is facilitated if there is a gradient of pressure between the vitreous cavity and the csf , or in a predisposed on head , such as in the presence of an on pit.12
in conclusion , one possible explanation for the occurrence of simultaneous bilateral malignant glaucoma is that the entrapment of aqueous humor behind the posterior vitreous face can establish a pressure gradient between the vitreous cavity and the fluid around the orbital on .
this facilitates the migration of fluid to the sas of the on , and then to the sas of the contralateral orbital on , either directly through the optic chiasm or due to increased intracranial csf pressure .
the fluid subsequently migrates to the vitreous cavity of the contralateral eye and pushes the total vitreous core anteriorly ; this precipitates forward movement of the anterior hyaloid face and lens  iris diaphragm , resulting in malignant glaucoma in the contralateral eye .
this postulated mechanism could also explain the observed phenomenon of immediate constriction of the contralateral pupil when a strong miotic agent is injected into the ac of the first eye upon completion of the phakic posterior chamber intraocular lens ( piol ) implantation in a planned bilateral piol surgery .
given this observed phenomenon , we avoid the injection of miotic agents into the ac upon completion of surgery on the first eye in the setting of bilateral implantation of phakic piol .
although it is very rarely indicated in our surgical practice of cataract surgery , the same phenomenon is observed during bilateral cataract surgery .
one more lesson to learn from this case is that severe iop elevation causes symptoms that can mimic those of certain central nervous system disorders .
finally , the diagnosis of idiopathic malignant glaucoma is challenging because , on the one hand , it is an uncommon entity , and on the other hand , early intervention with vitrectomy could possibly maintain good visual acuity and prevent blindness .

Answer:
purposemalignant glaucoma , or aqueous misdirection syndrome , is a condition characterized by sudden intraocular pressure ( iop ) elevation , and it is usually unilateral and induced by ocular surgical intervention or by medical therapy . here , we report a case of simultaneous bilateral malignant glaucoma in a young patient with no history of any ocular diseases.case reporta case of a 24-year - old female with no apparent previous history of ocular medical or surgical conditions was referred to our hospital because of recent bilateral iop elevation associated with a severe drop in vision and shallow anterior chamber with no posterior segment anomalies detected by ocular ultrasound in both eyes .
 yttrium aluminum garnet ( yag ) laser iridotomy dropped the iop only temporarily and the patient received topical atropine treatment with combined trabeculectomy and anterior vitrectomy.resultsin this case , the patient had a typical presentation of bilateral malignant glaucoma and her iop dropped only temporarily following laser iridotomy to rise again shortly thereafter .
 also , deepening of the anterior chamber and iop decrease after topical atropine was very supportive of the diagnosis of malignant glaucoma .
 successful management with trabeculectomy and limited vitrectomy also affirmed the diagnosis of malignant glaucoma.conclusionthis is a very rare case of bilateral malignant glaucoma in a young adult without any prior eye conditions ; only one similar case has been reported in the literature .
 we propose our own theory regarding this simultaneous occurrence of the pathology based on previously published studies about the presence of communication between the two eyes along the cerebrospinal fluid pathways .


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:
periodontal health can be described as  a dynamic state where the activity of proinflammatory / antimicrobial cytokines to control infection is optimally balanced by anti - inflammatory mechanisms to prevent unwarranted inflammation  . in subjects susceptible to periodontal disease ( pd ) , an imbalance of the inflammatory response results in excessive production of proinflammatory cytokines and the subsequent loss of periodontal attachment . on the other hand ,
furthermore , the release of tissue regenerating factors may contribute to periodontal regeneration by regulating the function of periodontal ligament cells , endothelial cells , and cementoblasts . in this
setting , neurotrophin brain - derived neurotrophic factor ( bdnf ) has been reported to enhance periodontal tissue regeneration [ 4 , 5 ] .
bdnf is a member of the neurotrophin family which is expressed by vascular endothelium and osteoblastic , immune , and neuronal cells .
bdnf is reported to be involved in the joint inflammatory process and its production is increased in response to proinflammatory cytokines . although a role for bdnf in periodontal regeneration has been proposed , no information is available concerning bdnf and periodontal disease .
the aim of this study was to measure the levels of bdnf in periodontal tissues from patients with chronic periodontitis .
the presence of polymorphisms rs6265 and rs4923463 of the bdnf gene and its correlation with inflammatory and clinical parameters were also assessed .
twenty - eight patients with cp , treated at the periodontal clinic , school of dentistry , at universidade federal de minas gerais ( ufmg , brazil ) , were enrolled in this study .
patients in this study met the following inclusion criteria : previous history of cp , diagnosed according to previously described criteria : ( 1 ) exhibiting more than one tooth with probing depth higher than 5  mm , ( 2 ) exhibiting more than two sites with clinical attachment loss deeper than 6  mm , and ( 3 ) exhibiting lesions distributed in more than two teeth in each quadrant .
patients who met the following criteria were excluded : ( 1 ) having a history of smoking , ( 2 ) use of antibiotic , ( 3 ) usage of anti - inflammatory and/or immunosuppressive medications during the 6 preceding months , and ( 4 ) a history of any systemic diseases ( i.e. , immunologic and autoimmune disorders , diabetes mellitus ) .
the control group ( hc ) comprised 29 age and gender matched periodontally healthy patients enrolled for third molar removal surgery .
periodontal examination was performed in both groups of patients , cp and hc , at the initial visit to determine probing depth ( pd ) , clinical attachment loss ( cal ) , and bleeding on probing ( bop ) .
measurements were performed full - mouth at 6 sites per tooth ( mesiobuccal , midbuccal , distobuccal , mesiolingual , midlingual , and distolingual ) .
all the measurements were performed by the same examiner . at the time of the examination a peripheral blood sample
periodontal tissue samples from periodontal pockets or healthy oral mucosa extracted during surgery of impacted third molars were fixed in 10% buffered formalin , embedded in paraffin wax , and cut longitudinally ( 3  m ) .
the sections were deparaffinized , rehydrated , and stained with h&e for evaluation of the inflammatory infiltrate .
inflammatory cells were counted in four fields in two independent sections , using a light microscope ( axioskop 40 zeiss ; carl zeiss , gottingen , germany ) at 400x magnification .
the concentrations of the il-17a , bdnf , il-10 , and tnf- and the chemokine cxcl10 were measured in periodontal tissues by enzyme - linked immunosorbent assay ( elisa ) using commercially available kits ( r&d systems , minneapolis , mn , usa ) .
the lower limit of detection for each cytokine was 15  pg / ml , 3.9  pg / ml , 5.5  pg / ml , 20  pg / ml , and 4.5  pg / ml , respectively , for il-17a , il-10 , tnf- , bdnf , and cxcl10 . the data were determined using a standard curve prepared for each assay and expressed as picograms of cytokine / chemokine per 100  mg of tissue .
periodontal tissue samples were also used for determination of myeloperoxidase ( mpo ) activity , a neutrophil enzyme marker , as described earlier .
the mpo activity in homogenized periodontal tissues was evaluated by enzymatic reaction and absorbance was measured at 450  nm .
the mpo content was expressed as relative units calculated from standard curves based on mpo activities from 5% casein peritoneal - induced neutrophils assayed in parallel .
total genomic dna was extracted from blood samples using qiaamp dna blood mini kit ( qiagen , valencia , ca , usa ) according to manufacturer 's instructions .
quality , integrity , and quantity of dna were analyzed by nanodrop spectrophotometer ( thermo scientific , wilmington , de , usa ) .
all amplifications were carried out in an abi 7900h thermal cycler ( applied biosystems , foster city , ca , usa ) using taqman genotyping master mix and following manufacturer 's recommended amplification conditions .
chi - square test analysis was used to test for deviation of genotype frequencies from hardy - weinberg equilibrium .
the levels of cytokines in periodontal tissues and the frequency of gene polymorphisms were compared by the student 's t - test and chi - square tests .
the sample included in the current study was composed by age and gender matched groups .
the clinical features pd , cal , and bop were significantly higher in the cp than in the hc group ( p < 0.0001 ) ( table 1 ) .
the levels of il-17a , cxcl10 , il-10 , tnf- , and bdnf in periodontal tissues were greater in cp patients than in controls ( figure 1 ) .
moreover , the mpo activity and the inflammatory infiltrate in the periodontal tissues , characterized by polymorphonuclear and mononuclear leukocytes , were significantly higher in the cp than in the hc group ( figure 2 ) .
the bdnf and il-10 levels in periodontal tissues were negatively correlated ( r = 0.691 , p = 0.002 ) , whereas no correlation between bdnf and il-17a , tnf- , cxcl10 , or clinical parameters was observed ( pd , cal , and bop ) . following the clinical investigation , the frequencies of polymorphisms ( bdnf ) were assessed in blood samples of hc and cp subjects ( table 2 ) . the frequency of these genotypes agreed with the hardy - weinberg equilibrium ( p > 0.05 ) .
the distribution of the bdnf polymorphisms was similar between the groups ( table 2 ) .
we also investigated whether some of these polymorphisms were associated with worse clinical periodontal parameters .
as shown in table 3 , no differences in clinical parameters were found when comparing the genotypes .
the levels of bdnf and the inflammatory mediators cxcl10 and tnf- were increased in gg genotype of bdnf rs6265 polymorphism ( figures 3(a ) , 3(b ) , and 3(c ) ) , but mpo levels did not alter significantly ( figure 3(d ) ) . in bdnf
rs4923463 polymorphism the levels of bdnf and mpo did not differ , but the levels of cxcl10 and tnf- were higher in patients with aa genotype ( figures 3(e)3(h ) ) .
a wide range of nonneural cells in peripheral tissues or in the immune system expresses neurotrophins and their receptors .
thus , the mitogenic and immune regulatory functions of neurotrophins have been discussed [ 6 , 1012 ] .
the neurotrophin bdnf is reported to be involved in inflammatory reactions , and its production is increased in response to proinflammatory cytokines .
the present study is the first to demonstrate that bdnf levels were increased in periodontal tissues from chronic periodontitis compared to healthy subjects . in agreement with our findings
, bdnf was found in high levels in the plasma of patients with osteoarthritis   and in patients with rheumatoid arthritis .
while some authors   reported that bdnf levels were significantly correlated with self - reported pain , others   did not find association between bdnf and clinical parameters of arthritis .
several studies analyzed bdnf rs6265 polymorphisms in psychiatric disorders [ 1618 ] . to date , few studies examined the rs4923463 polymorphism [ 16 , 1820 ] .
while one study found correlation between snp rs4923463 and attention - deficit / hyperactivity disorder , schizophrenia , and risk of suicide in bipolar disorder , another study did not find any correlation between schizophrenia and rs4923463 polymorphism .
previously , two studies have evaluated the effects of bdnf polymorphisms in bone [ 21 , 22 ] , but there are no available studies in periodontal disease . in the present study we did not find differences in bdnf genotype distribution between patients with cp and controls .
nevertheless , we found that subjects with gg ( rs6265 ) genotype expressed higher levels of bdnf in periodontal tissues , in agreement with a previous report showing that bdnf - m66 variant alters intracellular trafficking and impairs bdnf secretion . on the other hand , rs6265 polymorphism
interestingly , the snp rs6265 was reported as a phossnp , which means this snp regulates protein phosphorylation .
the snp rs6265 affects substrate - kinase interaction between bdnf protein and chek2 kinase and regulates bdnf phosphorylation at site t62 .
subjects aa genotype carriers exhibited lower bone mineral density compared to g carriers . specifically , bdnf - v66 ( major allele g at rs6265 ) transfection significantly increases expression of osteoblast specific markers ( opn , bmp2 , and alp ) and promotes osteoblast differentiation and maturation in cell culture .
an association of rs6265 with bone metabolism was also suggested in the largest meta - analysis involving 32,961 individuals of european and east asian ancestry .
they found that homozygous minor allele a carriers ( aa ) have significantly decreased bmd compared to major allele g carriers ( ga and gg ) .
it has been reported that bdnf is able to induce an increase in il-10 expression . however , a negative correlation between the production of bdnf and il-10 was observed in samples from patients with periodontitis .
il-10 can inhibit the release of proinflammatory cytokines from monocytes / macrophages and can therefore inhibit the lipopolysaccharide- and ifn--induced secretion of inflammatory cytokines ( e.g. , tnf- , il-1 , il-6 , cxcl8 , and others ) . in periodontal disease , il-10 is thought to be associated with lower disease severity .
previous studies demonstrated that bdnf induces periodontal tissue regeneration by activation of cementoblasts differentiation , vascular endothelial cell migration , and also has a positive effect on bone remodeling [ 5 , 28 ] .
this data together suggested that bdnf has a role in bone remodeling and any change in this neurotrophin levels could have an impact in bone repair .
finally , we observe that cp subjects with gg ( rs6265 ) and aa ( rs4923463 ) genotypes demonstrated increased levels of tnf- and cxcl10 .
cxcl10 has several roles , such as chemoattraction of macrophages , t cells , nk cells , and dendritic cells .
in addition , previous studies showed that exposure to bdnf substantially and synergistically enhanced tnf- levels in vitro , and tnf- preconditioning increased proliferation , mobilization , and osteogenic differentiation in vitro .
we can hypothesize that the concomitant increase of bdnf , tnf- , and cxcl10 in patients with the gg genotype may be an attempt of the host to induce periodontal healing .
so , maybe if these patients were examined after periodontal treatment , they could display higher and better levels of tissue regeneration compared to patient who do not exhibit the gg genotype .
in conclusion , bdnf seems to be related to periodontal pathogenesis and also involved in tissue repair .
the results obtained here provide a benchmark for future studies with a large cohort of patients to help strengthen and understand the influence of neurotrophins in periodontal disease .

Answer:
brain - derived neurotrophic factor ( bdnf ) is a member of the neurotrophic factor family . outside the nervous system
 , bdnf has been shown to be expressed in various nonneural tissues , such as periodontal ligament , dental pulp , and odontoblasts .
 although a role for bdnf in periodontal regeneration has been suggested , a function for bdnf in periodontal disease has not yet been studied .
 the aim of this study was to analyze the bdnf levels in periodontal tissues of patients with chronic periodontitis ( cp ) and periodontally healthy controls ( hc ) .
 all subjects were genotyped for the rs4923463 and rs6265 bdnf polymorphisms .
 periodontal tissues were collected for elisa , myeloperoxidase ( mpo ) , and microscopic analysis from 28 cp patients and 29 hc subjects .
 bdnf levels were increased in cp patients compared to hc subjects .
 a negative correlation was observed when analyzing concentration of bdnf and il-10 in inflamed periodontium .
 no differences in frequencies of bdnf genotypes between cp and hc subjects were observed .
 however , bdnf genotype gg was associated with increased levels of bdnf , tnf- , and cxcl10 in cp patients . in conclusion
 , bdnf seems to be associated with periodontal disease process , but the specific role of bdnf still needs to be clarified .


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:

 hepatitis b virus ( hbv ) is a major health problem , with approximately 400 million chronically infected people worldwide , and 1560% of the normal population in many african countries may be positive for one or more of the serological markers of hepatitis b virus infection .
these chronically infected patients not only are at an increased stage of developing liver cirrhosis and hepatocellular carcinoma , but also serve as a potential reservoir of infection . the major structural protein of virus envelope , hepatitis b surface antigen ( hbsag ) , is universally considered as a diagnostic marker of hbv infection .
the absence of hbsag in the serum and the presence of antibodies to core antigen ( anti - hbc ) usually indicate resolved infection .
occult hbv infection ( obi ) usually has a serological evidence of previous hbv infection that has been described in a few cases .
hiv coinfection has been reported to modify the natural history of hbv with potential consequences on morbidity and mortality .
data on obi in art untreated hiv patients is limited from a vast number of african countries like nigeria , where prevalence of hbv monoinfection , mode of transmission , viral genotype , and mutational pattern varies considerably in different parts of the country .
no previous study from nigeria on prevalence on obi among any groups has been carried out .
this is particularly important as exposure to hbv is common among hiv - infected cases because of shared routes of transmission .
notably , there is considerable variation in prevalence of hiv / hbv coinfection according to geographic regions and exposure risk .
successful implementation of art leads to immune reconstitution that can potentially result in immune mediated liver injury in the setting of hbv coinfection .
some studies have reported an association between obi and elevated transaminase ; therefore identification of obi is of importance .
of the 1,200 hiv - infected patients enrolled in the haart clinic of the specialist hospital , ikole , ekiti state , nigeria , from october , 2012 , to april , 2013 , we identified 980 hbsag negative patients ( art - nave subjects ) . among them , 188 were selected for the study by a simple random method .
informed consent was obtained from the patients , and the institutional committee approved the study protocol .
all samples were tested for hbsag , anti - hbs , anti - hbc , anti - hcv , and anti - hiv using elisa ( drg diagnostics , marburg , germany ) .
all anti - hbc positive samples were retested for hbsag as well as for anti - hbc , and only repeat positive samples were included in the study .
dna was extracted from all the serum samples using qiaamp dna blood mini kit ( qiagen gmbh , hilden , germany ) following the manufacturers ' instructions .
briefly , samples ( 200  l ) were incubated with protease and lysis buffer .
after incubation , there were two washing steps , and the nucleic acids were eluted in a volume of 50  l of elution buffer .
the presence of hbv dna was examined in all samples using a routine diagnostic pcr .
primer pairs were designed from the highly conserved overlapping regions of the s and p genes of the hbv genome .
a nested pcr was performed : outer primer pairs were hbpr134 ( sense ) 5-tgctgctatgcctcatcttc-3 and hbpr135 ( antisense ) 5-cagagacaaaagaaaattgg-3 and the inner primer pairs were hbpr75 ( sense ) 5-caaggttatgttgcccgtttgtcc-3 and hbpr94 ( antisense ) 5-ggtataaagggactcacgatg-3. pcr amplifications were carried out in 25  l reaction volumes with 5  ng of genomic dna , 10x pcr buffer ( 20  mm tris - hcl ph 8.4 , 50  mm kcl ; qiagen ) , 2  mm of dntps , 50  ng of each primer , and 1  u ampli taq gold dna polymerase ( applied biosystems ) on a ptc 200 cycler ( peltier thermal cycler watertown , massachusetts , usa ) .
thermal cycling parameters were initial denaturation at 94c for 2  min , followed by 35 cycles of 30  sec at 94c denaturation , 30  sec at 52c annealing temperature , and 45  sec at 72c extension , followed by a final extension of 5  min at 72c .
thermal cycling parameters remained the same as in the first pcr round except for the number of cycles that is increased to 40 cycles of amplification .
each pcr product ( 5  l ) was analysed by electrophoresis in 2% agarose gels . a positive control ( hbv plasmid dna ) and a negative control of the master mix only were integrated to each run to validate the pcr products that yielded a 340  bp fragment .
quantification of hbv dna was performed with quantitative real - time pcr using a previously described procedure   in a geneamp 7300 sequence analyzer ( applied biosystems , perkin - elmer , foster city , ca ) .
hbv - plasmid dna was used to generate a standard curve following a serial 10-fold dilution .
mean age and all the numerical data were analysed using student 's   t - test .
the chi - square test and fisher 's exact test were used to compare categorical data . for the purpose of our study ,
the demographic , biochemical , and virological parameters of the study group are summarized in table 1 .
the mean age was 35 ( range : 367 ) years . the majority ( 45% ) had multiple sexual partners and 25% of the subjects had a history of concomitant alcohol use .
overall , 29/96 ( 29.2% ) of patients were reactive for anti - hbc , an indication of prior exposure to hbv dna , and majority 6/8 ( 75% ) of the patients were female ( table 2 ) .
thus , in the total study population , 21/188 ( 11.2% ) of patients were identified as obi and 62.5% of the obi patients had cd4 count less than 200  cells / mm .
averagely the hbv viral load was < 50  copies / ml in the obi samples examined by quantitative pcr .
serum levels of ast and alt were higher among patients with obi in comparison to anti - hbc positive hbv dna negative individuals , but the difference failed to reach standard significance ( p = 0.13 and p = 0.07 ) , respectively .
the comparison of different demographic , biochemical , and virological factors between hbv dna positive and negative cases was illustrated in table 3 .
the distribution of the study participants as per the 1993 revised classification system for hiv infection and expanded surveillance case definition for aids among adolescents and adults was as shown in table 4 .
the present study represents a comprehensive cross - sectional analysis of prevalence of obi in an art nave hiv positive cohort comprising various risk groups .
most previous studies looking at the clinical effects of obi in hiv include a large number of patients on anti - hbv drugs as a component of art .
this study describes the risk factors associated with obi , frequently of anti - hbc positivity and its possible values as a serological marker for identifying hiv - infected patients who benefit from hbv dna assay .
we found the prevalence of occult hbv to be 11.2% among a random selected group of hiv - infected patients .
the prevalence of obi in hiv positive individuals varies worldwide between 0 and 90% , depending on the geographic regions , risk factors , and the exposure involved . in the present study ,
the prevalence of anti - hbc ( 29.2% ; 28 of 96 ) and obi ( 28.6% ; 8 of 28 ) among the art nave hiv positive cohort was higher compared to previous report on blood donors from studies done in areas of india , areas which reported 21.3% obi among the hbsag negative anti - hbe positive donors . within nigeria , hbv and hcv coinfection among hcv - infected patients
most of the previous studies on hbv / hiv co - infection are aimed at detecting hbv prevalence in the hiv population are based on hbsag positivity ( prevalence 9.9 to 11% ) , but reports on obi are scarce .
a previous study on intravenous drug users in northeastern india detected a prevalence of 15.9% . among the obi cases , the rate of anti - hbs was lower ( 2/8 ; 25% ) , which may be due to the fact that hiv - infected patients are prone to lose anti - hbs immunity at a higher frequency than the general population .
previous reports suggested that the lower hbv replication was associated with milder hepatic damage . among the subjects with obi , elevated alt or ast
however , our study is cross - sectional ; therefore evaluation of long term clinical significance of obi should be better addressed by follow - up studies .
the low level of viral load obtained in this study buttress the findings in another study that showed that showed that almost all obi cases are infected with replication incompetent hbv , revealing a strong suppression of overall replication activity and gene expression , thereby resulting in a significant reduced viral load .
hiv patients are screened for concomitant chronic hepatitis b using hbsag elisa , and it is not considered cost - effective to perform hbv dna testing for all hiv patients in our resource - poor setting . our study tried to identify possible clinical and serological markers which could guide dna testing in these patients .
obi is reported to be common among hcv infection , but we found its prevalence to be low among our study group
. however , anti - hcv was not tested among the other hiv positive samples attending the specialist hospital , ikole , ekiti state , nigeria .
furthermore , none of the risk factors were found to be statistically significant markers of obi and can not be used as an independent marker for identifying patients who should benefit from hbv dna estimation .
however , as one third of the anti - hbc positive negative patients were positive for hbv dna ( 8 of 28 ) , it is recommended that hiv positive patients with hbsag negative / anti - hbc positive patterns should be tested for the presence of hbv dna irrespective of their anti - hbs status .
nevirapine is commonly included in the first line art regimens at most treatment centers in nigeria .
our study identified only 21 subjects with obi , and all the samples were collected from a single center indicating that results might differ in setting with significant different demographic characteristics .
a main implication of the presently viable data is therefore further emphasizing the need for efficient hbv vaccination programs .
overall , the present study highlights the need for screening hbv before the initiation of any haart containing anti - hbv regimens in hbv / hiv coinfected patients .
it necessitates the use of nat for effective laboratory diagnosis of occult hbv infections in hiv positive patients , especially in developing countries where these assays are not widely available .

Answer:
hiv has been known to interfere with the natural history of hepatitis b virus ( hbv ) infection . in this study
 we investigate the prevalence of occult hepatitis b virus infection ( obi ) among hiv - infected individuals in nigeria .
 overall , 1200 archived hiv positive samples were screened for detectable hbsag using rapid technique , in ikole ekiti specialist hospital .
 the hbsag negative samples were tested for hbsag , anti - hbc , and anti - hcv by elisa .
 polymerase chain reaction was used for hbv dna amplification and cd4 counts were analyzed by cytometry .
 nine hundred and eighty of the hiv samples were hbsag negative .
 hbv dna was detected in 21/188 ( 11.2% ) of patients without detectable hbsag .
 cd4 count for the patients ranged from 2 to 2,140 cells/l of blood ( mean = 490 cells/l of blood ) .
 hcv coinfection was detected only in 3/188 ( 1.6% ) of the hiv - infected patients ( p > 0.05 ) .
 twenty - eight ( 29.2% ) of the 96 hiv samples screened were positive for anti - hbc .
 averagely the hbv viral load was < 50 copies / ml in the obi samples examined by quantitative pcr .
 the prevalence of obi was significantly high among hiv - infected patients .
 these findings highlight the significance of nucleic acid testing in hbv diagnosis in hiv patients .


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 clinical practice , paradoxical clinical results that require alternative strategies may be encountered . here
we present a case of a patient with results of cardiac catheterization that are incompatible with st segment elevation and elevated cardiac enzymes .
although technologically advanced diagnostic examinations are becoming increasingly available , noninvasive bedside ultrasound examination remains to be indispensable .
although cardiac myxomas are relatively uncommon compared with coronary and valve lesions in the elderly , they are easily diagnosed by basic echocardiography ; this diagnostic test may be the key to solving puzzling presentations and should a part of most cardiac workups .
stroke is a complication in 10% to 30% of cardiac myxoma patients as found in a case series spanning 20 years in belgium and a 11-year series conducted at the mayo clinic ; no cases of cardiac myxoma in either study had concurrent myocardial infarction .
forty cases of myxoma - related myocardial infarction were recorded in a systematic review of published data spanning 32 years .
this case report shares our experience with a rare case of cardiac myxoma with concurrent stroke and st - elevation myocardial infarction with normal coronary angiography .
signed consent from the patient was obtained , and approval was granted by the institutional review board of taipei tzuchi hospital for this case report . a 67-year - old unconscious woman presented to the emergency department of our hospital within 30 minutes of collapsing at an outdoor market
. she was afebrile with blood pressure of 100/80 mm hg , heart rate of 90 beats per minute , and respiratory rate of 26 breaths per minute on mask oxygen .
on physical examination , the patient displayed grimace in response to painful stimuli , pupils were equal and reactive to light , heart beats were regular without obvious murmurs , breath sounds were coarse without wheezing , abdomen was soft and nontender , urine was clear with adequate output into a foley bag , and legs were warm and nonedematous ; examination was otherwise unremarkable .
electrocardiogram showed significant st elevation in the inferior and lateral leads ( figure 1 ) .
chest x - ray showed lung congestion , minimal effusion in the pericardial and pleural spaces , and a narrow mediastinum . computed tomography of the brain showed no hemorrhage or detectable ischemia . although awaiting cardiac catheterization , she regained consciousness and was able to follow commands and move all extremities . however , severe orthopnea with respiratory distress developed , and she was endotracheally intubated .
we then performed echocardiography , which revealed an oscillating round mass measuring 3  3  cm inside the left atrium attached by a pedicle to the interatrial septum that was obstructing inflow through the mitral valve during diastole ( figure 2 ) .
although in the intensive care unit , the patient 's lung edema deteriorated rapidly , resulting in cardiogenic shock that required increased inotropic support and high - setting ventilator support .
echocardiograph of the oscillating left atrial myxoma ; surgical specimen of the completely resected atrial myxoma .
the myxoma was resected en bloc with its pedicle and adjacent interatrial septum ( figure 2 ) .
ataxia was noted during rehabilitation , and magnetic resonance imaging of the brain revealed left cerebellar infarction .
cardiac atrial myxoma is uncommon , with an estimated incidence of <  0.1% by autopsy series .
often initially asymptomatic , symptoms arise because of obstructive , embolic , or constitutional events .
a 20-year surgical cohort of cardiac myxoma cases in belgium estimated 65.6% of presenting symptoms to be obstructive and 15.6% to be embolic . as in our case
, emergent resection may be necessary if cardiogenic shock develops because of mitral valve obstruction .
echocardiography can readily reveal obstruction by a cardiac myxoma , usually of mitral valve inflow , allowing timely determination of severity and necessity for emergent surgical resection .
myxoma - related stroke is relatively more common than myxoma - related myocardial infarction for myxoma - related embolic events . in the aforementioned 20-year myxoma surgical series ,
brain ischemia was involved in 15.6% of cases , brain and peripheral artery embolic ischemia in 6.2% , and angina in 3.1% , whereas no cases involved myocardial infarction .
myxoma - related coronary artery embolism is rare and much less common than brain embolism .
estimated incidence of myocardial infarction in cardiac myxoma ranges from close to 0% to as high as 10% if coronary emboli is included .
a review of cardiac myxoma cases spanning 11 years conducted by the mayo clinic found that 12% of cases had image - evident stroke .
therefore , coexisting stroke and myocardial infarction , as in our case , are exceedingly unusual .
myocardial infarction with normal immediate angiography is rare for cardiac myxoma . in a systematic review of published data from 1970 to 2002 ,
patent coronary arteries were found only on latent angiography ( performed more than 2 weeks after the initial event ) , but not on immediate angiography .
negative latent angiography may be explained by recanalization performed days or weeks after the initial coronary events .
possible explanations may include rapid and spontaneous recanalization , a washout effect of embolic myxoma fragments or induced thrombi , or compromised hemodynamics because of mitral valve obstruction .
echocardiography , a noninvasive and portable examination , is often critical for properly identifying the etiology of cardiac conditions such as acute heart failure .
basic echocardiography , or focused cardiac ultrasound , is easily learned and often sufficient for detecting intracardiac masses or intrathoracic effusion .
our case demonstrates the importance of basic echocardiography for optimizing the management of cardiac cases , and supports the recommendation that basic echocardiography be readily available for most cardiac teams or acute care centers .
our atypical case of normal immediate coronary angiography in myxoma - related myocardial infarction with mitral valve obstruction and multisystem embolism ( heart and brain ) deserves attention because of the rarity of this combination of presentations .
the case stresses the value of basic echocardiography in the efficient and effective management of the patient and the importance of including it in most cardiac workups .
in addition , this experience is a reminder for clinicians to include cardiac myxoma in the differential diagnosis list and to manage it timely if found .
although cardiac myxoma may have unexpected presentations , it can be easily diagnosed by basic echocardiography and should not be missed .
once diagnosed , cardiac myxoma requires timely surgical en bloc resection to avoid deterioration resulting from worsening embolism or obstruction .

Answer:
abstractwe present a case of cardiac myxoma with atypical presentations of concurrent stroke and angiography - negative myocardial infarction .
 the case emphasizes the importance of basic echocardiography and timely surgery in the management of cardiac myxoma.an elderly woman presented to the emergency department in an unconscious state . electrocardiogram and
 elevated cardiac enzymes suggested acute myocardial infarction ; however , immediate coronary angiography proved patency .
 basic echocardiography revealed an oscillating left atrial myxoma obstructing inflow through the mitral valve . after regaining consciousness while in the intensive care unit , the patient developed respiratory distress and shock , and emergent en bloc resection was performed .
 ataxia was noted in her postoperative course and multiple small cerebellar infarcts were found on magnetic resonance imaging . after a 1-month period of rehabilitation ,
 the patient recovered well and continues to be followed as an outpatient.cardiac myxoma requires timely management and may be missed if not included in the differential diagnoses .
 basic echocardiography , also called focused cardiac ultrasound , may aid in the diagnosing of perplexing cardiac cases .


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:
diarrhea , including that of parasitic origin , remains one of the most common illnesses among children and , as reported by the world health organization , is one of the major causes of infant and childhood mortality in developing countries .
intestinal opportunistic parasitic infections are important causes of diarrhea which is a serious health problem in tropical regions .
are common parasitic causes of human diarrhea with the prevalence rate of 1%3% in the industrialized world and 4%-17% in developing countries . in developed countries , massive cryptosporidium food borne and waterborne outbreaks
have been reported because cryptosporidium oocysts are not killed by conventional disinfectants and chlorination . in developing countries
, cryptosporidium affects mostly children under five years of age and has been reported to be more common in malnourished than in well - nourished children[4 , 5 ] .
 c. parvum
, a protozoan parasite of the phylum apicomplexa , is an enteric pathogen that causes an acute as well as chronic diarrhea in humans .
the human host range is broad and includes people with immunodeficiency , children in developing countries , and outbreaks among immuno - competent individuals . in a healthy adult
, infection often results in a self - limited diarrheal illness , however , in children of developing countries , cryptosporidiosis can result in persistent diarrhea leading to malnutrition and developmental delays .
indeed , cryptosporidium is still an under - diagnosed cause of diarrheal illness in children .
few reports with relatively small sample sizes are available on the prevalence and clinical presentation of cryptosporidium infection in both immuno - compromised and immune - competent children in iran[713 ] .
the purpose of this study was to determine and compare the prevalence of c. parvum infection in children with an acute or persistent diarrhea in isfahan city , central iran .
this cross - sectional study was prospectively conducted in three university hospitals in isfahan from august 2007 to june 2008 .
children aged one month to 10 years presenting with acute or persistent diarrhea were visited in each hospital by one of the researchers ( pediatrician ) of the study and were included consecutively .
diarrhea was defined as the passage of abnormally liquid or unformed stools at an increased frequency and further defined as acute if lasted < 2 weeks and persistent if lasted for 2 to 4 weeks before admission .
children who had used antiparasitic or antibiotic drugs before admission and also those with known hematologic diseases and immuno - compromised children were excluded from the study . assuming the average prevalence of c. parvum to be 5% according to previous reports , and a margin error of 2% ( difference between estimated and reported prevalence ) and 95% confidence , a sample size of 456 was calculated for determining the overall prevalence of c. parvum .
fecal samples were collected in sterile plastic bottles and were transported without preservative and arrived in the central laboratory of isfahan city within 24 hours of collection .
the oocyst of c. parvum was tested using a modified acid - fast staining method which is a sensitive and specific approach for the identification of cryptosporidium and coccidian oocysts in stools . in this technique ,
the oocysts appear as pink to red , spherical to ovoid bodies on a blue or purple background .
the study protocol was approved by the ethical committee of isfahan university of medical sciences and consent was obtained from the parents .
the chi - square test was used to compare relative frequency of cryptosporidium infection between children with acute and persistent diarrhea .
independent t - test was used to compare the mean age between infected and non - infected children .
during the study period , 606 children aged one month to 10 years were presented with acute or persistent diarrhea to three university hospitals in isfahan .
there were 254 ( 41.9% ) males and 352 ( 58.1% ) females with the mean age of 42.430.0 months .
acute or persistent diarrhea was present in 422 ( 69.6% ) and 184 ( 30.4% ) of the children , respectively .
cryptosporidium oocysts were detected in 12.5% ( 23/184 ) of the children with persistent compared to 1.2% ( 5/422 ) of the children with acute diarrhea ; p<0.001 .
most ( 89.2% ) of the infected children were under 5 years of age , however , the age difference between the infected and non - infected children was not statistically significant ; p=0.1 . also , there was no significant sex difference between the infected and non - infected children ; p=0.5 ( table 1 ) .

comparison of infected and non - infected children the age difference between children with acute and persistent diarrhea was not statistically significant ( 43.933.4 vs 38.919.6 months , p=0.06 ) and there was no significant difference between the two sexes ( 248/174 vs 104/80 female / male ratio , p=0.6 ) .
intestinal parasites are very common in developing countries and cryptosporidium has revealed to be one of the most common parasites .
cryptosporidium infests the small intestinal epithelium , thereby , results in an accelerated loss of villous enterocytes , leading to severe villous atrophy and a malabsorptive and secretory diarrhea which is the most pronounced clinical feature of the infection .
other symptoms include dehydration , weight loss , stomach cramp , or pain , fever , nausea , and vomiting .
the infectious dose is low and feeding studies have demonstrated that the ingestion of as few as 1030 oocysts can cause infection in healthy persons .
infected persons have been reported to shed 1010 oocysts in a single bowel movement and to excrete oocysts for up to 50 days after cessation of diarrhea[16 , 17 ] .
there are discrepancies in the prevalence of cryptosporidiosis in children among surveys in different parts of iran .
the reported prevalence is from 1.5% in rasht ( northern city of iran ) to 21.4% in shiraz ( southern city of iran)[713 ] .
the difference in the reported prevalence may be attributed to differences in study population ( considering age range ) , diagnostic methods , environmental risk factors ( public water supply ) , time of the study ( summer vs winter ) , nutritional status of the children , and other risk factors[6 , 18 , 19 ] .
in other countries , the rates of cryptosporidiosis are 1%-2% in europe , 0.6%4.3% in north america , and 3%-10.2% in asia , australia , africa , and central and south america .
several methods are available for identification of cryptosporidial oocysts in fecal specimens including modified acid - fast staining which detects oocyst wall , fluorescein - conjugated monoclonal antibody - based detection of oocyst wall antigen , enzyme - linked immunosorbent assay ( elisa ) which detects cryptosporidial antigen and most recently polymerase chain reaction ( pcr ) which detects crytosporidial dna . modified acid - fast stain of a fecal smear has been the gold standard for detecting cryptosporidium oocysts in stool .
although the concentration and staining procedures are time- consuming and also require an experienced microscopist to read the slides , it is inexpensive and allows the detection of other parasites ( eg , isospora and cyclospora ) at the same time .
however , the sensitivity for the detection of cryptosporidium is substantially better with elisa formats or immunofluorescent assays .
pcr method is sensitive , but the cost and tedious methodology have limited its use in the clinical microbiology laboratory .
regardless of the method used , it is extremely important that the physician remembers to request cryptosporidial testing when stool from a child with diarrheal illness is to be examined for ova and parasites .
the results of the present study showed that children with cryptosporidiosis are more likely to present with persistent diarrhea , compared to acute diarrhea . in a report from southeastern iran , hamedi and
however , khalili and colleagues in their study on 171 children found no relationship between type of diarrhea and infection .
although our study did not show significant age difference between the infected and non - infected children , most of the infected children , as expected , were below 5 years old .
though humans are susceptible at any time in their lives , the prevalence of cryptosporidiosis is higher in younger children mostly in children aged below 5 years[8 , 10 , 11 ] .
the occurrence of high infection rates in younger children might be attributed to their weak immune responses and/or risk of contact with the oocysts . however , more studies are needed to confirm this subject[12 , 18 ] .
although the sample size of the study was large enough , sampling was consecutive and not random .
however , the study was multicenter and we conducted the study through one year , so it is unlikely that season or selection bias affected our results .
also we applied the modified acid - fast staining and although it is a sensitive and specific approach for the identification of cryptosporidium , elisa and immunofluorescent assays are more sensitive in this regard .
we recommend evaluating children for important risk factors for infection with cryptosporidium , such as nutritional and socioeconomic status , for future studies .
the prevalence of cryptosporidiosis in children presenting with persistent diarrhea is considerable and we suggest routine stool examination for cryptosporidium in these children for early diagnosis and treatment to prevent possible complications .
also , for control and prevention of this infection , strengthening water quality standards and improving sanitary practices are required .

Answer:
objectivecryptosporidiosis is an important enteric parasitic infection among infants and children in developing countries with significant morbidity and mortality especially among immuno - suppressed individuals .
 the aim of the present study was to estimate the prevalence of enteric cryptosporidiosis in children presenting with diarrhea in isfahan.methodsthis cross - sectional study was conducted from august 2007 to june 2008 in three university hospitals in isfahan .
 children aged 1 month to 10 years presenting with acute or persistent diarrhea were selected consecutively .
 the oocyst of c. parvum was investigated in stool specimens using a modified acid - fast staining method.findingsduring the study period , 606 children ( mean age 42.430.0 months , 58.1% female ) were recruited .
 acute and persistent diarrhea was present in 422 ( 69.6% ) and 184 ( 30.4% ) of the children , respectively .
 twenty eight ( 4.6% ) specimens were oocyst positive .
 the prevalence of cryptosporidium infection was significantly higher in children with persistent diarrhea compared to children with acute diarrhea ( 12.5% vs 1.2% ; p<0.001 ) .
 most of the infected children were under 5 years of age ( 89.2% ) , however , the age difference between infected and non - infected children was not statistically significant . also , there was no significant difference between infected and non - infected children in gender.conclusionthe prevalence of cryptosporidiosis in children presenting with persistent diarrhea is considerable and we suggest routine stool examination for cryptosporidium in this group of children .


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:
reinforced surveillance systems aimed at monitoring the introduction of chikv have been implemented in 6 departments in southeastern france , including the var department , where ae .
albopictus has spread since its introduction in 2004 , presumably from northern italy ( 4 ) . on august 29 , 2010 ,
a 7-year - old girl ( patient 1 ) with acute febrile syndrome , headache , and abdominal pain sought treatment in the city of frjus ( var ) 1 day after she had returned from rajasthan , india .
continuous chikv circulation in northern india districts has been reported during 20092010 ( www.promedmail.org ) .
three weeks after the notification of patient 1 , another young girl ( patient 2 ) experienced clinical symptoms that began on september 18 with fever , arthralgia , backache , headache , and retro - orbital pain .
patient 2 s physician reported that a young girl ( patient 3 ) , a close friend of her patient , showed clinical symptoms compatible with chikv infection at the same time .
patient 3 , who lives near patient 1 , had invited patient 2 to spend the night of september 15 at her home .
a serum sample from patient 3 was collected 1 week after onset of fever and monoclonal antibody capture elisa detected high titers of specific anti - chikv immunoglobulin m. the serum sample also showed a weak rt - pcr signal for chikv . given that patients 2 and 3 did not report any recent travel to areas endemic for chikv
no complications were recorded , but all 3 patients had persistent weakness and joint pain 3 months after the acute phase .
intensive mosquito control measures , including spraying for adult mosquitoes and destroying breeding sites , were undertaken around the patients residences and areas visited by confirmed case - patients .
no further cases were found by the active case finding system ( a local physician and laboratories network ) implemented for 45 days after the declaration of the last autochthonous case .
a molecular study of france/2010 chikv strains isolated in frjus obtained from patients 1 ( imported case ) and 2 ( autochthonous case ) was performed .
viral genomic rna was extracted from chikv grown once in mosquito c6/36 cells and then subjected to rt - pcr amplification by using a set of primers targeting the structural genes of chikv ( 7 ) . paired sequence analysis of the e26k
e1 junction showed that the 2 france/2010 chikv strains display a divergence rate < 0.05% at the nucleotide level , whereas 100% identity was observed at the amino acid level .
phylogenetic analysis demonstrated that these viral strains belong to a cluster that is closely related to strains from india within the ecsa lineage ( figure ) .
the france/2010 chikv isolate from patient 2 might be derived from an indian strain introduced by patient 1 ( index case ) .
genotypes e2 - 211 t , e2 - 312 m , e2 - 386a , 6k-8i , and e1 - 284e that are found in the currently circulating strains belonging to the ecsa lineage were identified in france/2010 chikv isolates ( 2,3,7 ) .
these isolates also display the genotype e1 - 211e specifically shared by viral strains belonging to the asian phylogenetic group ( table ) .
the residue ala at position e2 - 264 has not been previously described in any chikv strains .
phylogenetic relationships among chikungunya virus isolates from cases of chikungunya fever in france , based on complete e2 - 6k - e1 nucleotide sequence ( 2,771 nt ) analysis .
phylogenetic analysis was inferred by using the maximum - likelihood method as implemented in mega version 5 software ( www.megasoftware.net ) .
the sequence of the strains from france described in this study has been deposited in genbank ( accession number pending ) ; other sequences were retrieved from genbank .
* molecular signatures were based on the analysis of complete amino acid sequence e2 - 6k - e1 ( 923 aa ) .
the numbering of amino acid positions refers to the african isolate s27 ( genbank access no .
letters in parentheses after strain names refer to east / central / south africa ( a ) , asia ( b ) and west africa ( c ) phylogroups .
recent attention has focused on the predominant role of e1 and e2 proteins in successful chikv infection of the anthropophilic ae .
vector competence experiments with la runion/2006 chikv isolates demonstrated the importance of the newly acquired e1-ala226val substitution for efficient transmission by ae .
albopictus from northern italy and from southeastern france showed disseminated infection rates ranging from 75%90% for chikv strains with e1 - 226v ( 10 ) .
the 2 france/2010 chikv strains isolated in frjus have ala at position e1 - 226 ( table ) .
the presence of an asp residue at position e2 - 60 , found in most of the ecsa chikv strains , may in part counterbalance the less favorable transmission of e1 - 226a strain in ae .
albopictus ( table ) . the thr residue at position e2 - 211 potentiates the infectivity of chikv in ae .
the presence of e2 - 211 t in chikv isolates from france underlines the risk for emergence of a fully adapted viral variant if the e1 - 226v genotype was selected during continuous transmission within ae .
the efficient chikv transmission in italy and southeastern france sheds new light on its dissemination potential in europe from 1 index case , regardless of the viral genetic background and mosquito species in the region of origin of the imported chikv ( 1,10,11 ) . in emerging regions , such as italy and runion island , where the seroprevalence in the population was < 50%
however , > 2 years passed since the end of the epidemic in runion island before a local transmission of chikv was again detected . in europe
where sylvatic cycles are absent , vertical transmission may participate in the maintenance and/or cyclic reemergences of chikv .
albopictus that may have more efficient vertical transmission than mosquito populations in eastern italy and tropical regions ( 11,12 ) . in 2010 ,
southeastern france faced the concomitant emergences of dengue virus ( denv ) and chikv ( 13 ) . for each of these viruses ,
only 2 autochthonous infections were confirmed , which suggests that rapid detection and control measures implemented around imported and autochthonous cases have been efficient .
a recent report mentioned the dual emergence of chikv and denv in southeastern france and urged the implementation of specific surveillance and response measures to reduce the risk for arbovirus emergence ( 14 ) . since 2006 , a specific chikungunya / dengue national preparation and response plan based on rapid detection and investigation of imported and suspected autochthonous cases , mosquito control measures , and efficiency evaluation in the treated areas has been activated from may through november and then modified after annual debriefing meetings involving all partners . in 2010 , this model proved to be well adapted to the early detection and control of chikv and denv .
albopictus mosquitoes and the successful emergence of chikv in italy and france , reinforced surveillance and response to chikv and denv dissemination should become a higher priority in europe ( 15 ) .

Answer:
in september 2010 , autochthonous transmission of chikungunya virus was recorded in southeastern france , where the aedes albopictus mosquito vector is present .
 sequence analysis of the viral genomes of imported and autochthonous isolates indicated new features for the potential emergence and spread of the virus in europe .


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:
acute appendicitis and typhlitis are the most common causes of gastrointestinal surgical complications in children undergoing chemotherapy for acute leukemia with reported incidences of 0.54.4% and 1.76.7% respectively [ 14 ]
. early diagnosis by radiologic imaging is essential as appendicitis usually requires emergent surgical management .
in such situations , the clinician must also balance the risk of further immunosuppression and chemotherapeutic toxicities with the risk of delaying appropriate leukemia therapy .
a retrospective case review of all children 18 years of age diagnosed with acute leukemia at our institution between january 2002 and december 2011 was performed after obtaining institutional irb approval . amongst 154 children eligible , three ( 1.9% ) patients
appendicitis was diagnosed based on clinical , imaging and histologic findings . a 17-year - old girl with relapsed acute myeloid leukemia ( aml ) developed nausea , vomiting , mild lower abdominal pain and breakthrough menstrual bleeding three days into hospitalization for induction chemotherapy with cytarabine and mitoxantrone . on day fifteen
, her abdominal pain localized to the right lower quadrant ( rlq ) followed by fevers three days later .
eventually , she underwent a matched unrelated donor bone marrow transplant ( bmt ) and was in remission at seven - year follow - up . an 18-year - old girl with relapsed leukemia consistent with acute lymphoblastic leukemia ( all )
in addition to intermittent nausea , vomiting , and diarrhea , significant rlq pain with fever on hospital day nineteen ( maximum 39.5  c ) prompted an abdominal ct scan that showed an edematous , thickened appendix with surrounding inflammation .
she underwent an emergent laparoscopic appendectomy and pathology revealed a non - perforated appendix with inflammatory infiltrate without leukemic involvement .
she eventually underwent a matched related donor bmt and was in remission at three - year follow - up . a 10-year - old girl presented with generalized myalgias ,
fevers and gingival hypertrophy and was diagnosed with primary aml with maturation ( fab : m2 ) .
cytogenetics revealed no clonal abnormalities and aml panel fluorescent in - situ hybridization studies were normal . during hospitalization for induction chemotherapy , after five days of decitabine ( 20  mg / m / day ) on study and one dose of systemic cytarabine ( 100  mg / m / dose ) , she developed abdominal pain with high - grade fevers ( maximum 40.1  c ) .
abdominal ct scan demonstrated numerous fluid - filled edematous bowel loops with enhancement , fluid collections , and findings consistent with an inflamed appendix with fecalith .
an emergent laparotomy revealed gross soilage of the abdomen due to a perforated necrotic appendix eroding into the distal ileum and colon necessitating a diverting ileostomy and partial right colectomy . at the time of surgery , her absolute neutrophil count ( anc ) was 4.0810/l .
histopathology revealed immature myeloid cells , consistent with leukemic involvement of the appendix , in addition to inflammatory infiltrates .
parenteral antimicrobial therapy was continued for approximately 6 weeks during which chemotherapy was held to avoid further immunosuppression .
packed red blood cell and platelet transfusions were required within the first postoperative week following which no transfusion support was needed until resumption of standard chemotherapy about 8 weeks later . during this 8 week period ,
her anc fluctuated from 0.64 to 5.3310/l with counts of < 110/l noted only on 2 occasions at 24 days and 37 days from surgery .
she did not experience sustained neutropenia and , hence , no significant issues were noted during this 8 week period .
bone marrow biopsy twenty - five days from initiation of induction chemotherapy showed no morphologic features of aml . despite receiving only a short course of decitabine and one dose of systemic cytarabine , she achieved and maintained complete remission until resumption of standard intensive chemotherapy .
a 17-year - old girl with relapsed acute myeloid leukemia ( aml ) developed nausea , vomiting , mild lower abdominal pain and breakthrough menstrual bleeding three days into hospitalization for induction chemotherapy with cytarabine and mitoxantrone . on day fifteen , her abdominal pain localized to the right lower quadrant ( rlq ) followed by fevers three days later .
eventually , she underwent a matched unrelated donor bone marrow transplant ( bmt ) and was in remission at seven - year follow - up .
an 18-year - old girl with relapsed leukemia consistent with acute lymphoblastic leukemia ( all ) was hospitalized for chemotherapy with cytarabine and clofarabine .
in addition to intermittent nausea , vomiting , and diarrhea , significant rlq pain with fever on hospital day nineteen ( maximum 39.5  c ) prompted an abdominal ct scan that showed an edematous , thickened appendix with surrounding inflammation .
she underwent an emergent laparoscopic appendectomy and pathology revealed a non - perforated appendix with inflammatory infiltrate without leukemic involvement .
she eventually underwent a matched related donor bmt and was in remission at three - year follow - up .
a 10-year - old girl presented with generalized myalgias , fevers and gingival hypertrophy and was diagnosed with primary aml with maturation ( fab : m2 ) .
cytogenetics revealed no clonal abnormalities and aml panel fluorescent in - situ hybridization studies were normal . during hospitalization for induction chemotherapy , after five days of decitabine ( 20  mg / m / day ) on study and one dose of systemic cytarabine ( 100  mg / m / dose ) , she developed abdominal pain with high - grade fevers ( maximum 40.1  c ) .
abdominal ct scan demonstrated numerous fluid - filled edematous bowel loops with enhancement , fluid collections , and findings consistent with an inflamed appendix with fecalith .
an emergent laparotomy revealed gross soilage of the abdomen due to a perforated necrotic appendix eroding into the distal ileum and colon necessitating a diverting ileostomy and partial right colectomy . at the time of surgery , her absolute neutrophil count ( anc ) was 4.0810/l .
histopathology revealed immature myeloid cells , consistent with leukemic involvement of the appendix , in addition to inflammatory infiltrates .
parenteral antimicrobial therapy was continued for approximately 6 weeks during which chemotherapy was held to avoid further immunosuppression .
packed red blood cell and platelet transfusions were required within the first postoperative week following which no transfusion support was needed until resumption of standard chemotherapy about 8 weeks later . during this 8 week period , her anc fluctuated from 0.64 to 5.3310/l with counts of < 110/l noted only on 2 occasions at 24 days and 37 days from surgery .
she did not experience sustained neutropenia and , hence , no significant issues were noted during this 8 week period .
bone marrow biopsy twenty - five days from initiation of induction chemotherapy showed no morphologic features of aml .
despite receiving only a short course of decitabine and one dose of systemic cytarabine , she achieved and maintained complete remission until resumption of standard intensive chemotherapy .
appendicitis is seen in the general population with a lifetime cumulative incidence rate of 9% .
our calculated incidence rate of appendicitis in the setting of acute leukemia ( 1.9% ) correlates with the reported incidence of 0.54.4% .
leukemic involvement of the gastrointestinal tract as well as the treatment thereof can compromise the structural integrity of the intestinal wall .
moreover , atypical presentations of appendicitis are common in immunocompromised patients due to underlying malignancy and ongoing chemotherapy .
early symptoms such as nausea , vomiting , abdominal pain , and diarrhea are non - specific and may be attributed to chemotherapy side effects delaying accurate diagnosis .
in addition , typhlitis often mimics the classic presentation of appendicitis , and therefore imaging must be performed to distinguish these entities as their management approaches differ .
although successful conservative management has been reported , the majority require surgical intervention to avoid devastating complications .
several groups have demonstrated safety and efficacy of surgical intervention   and operative management may also shorten the length of hospital stay compared to nonoperative management . in our cohort ,
all three patients were operated upon emergently and all of them including the patient with appendiceal perforation and leukemic infiltration tolerated surgery well . for the treating clinician
, the bigger conundrum is the need to suspend chemotherapeutic treatment during life - threatening infections such as appendicitis , while weighing in a heightened risk for uncontrolled leukemic cell proliferation . alternatively ,
other anti - leukemic agents such as decitabine have been demonstrated to be effective and well - tolerated in adults with myelodysplastic syndrome , high risk aml , as well as those ineligible for standard chemotherapy due to extensive comorbidities such as the elderly [ 1113 ] .
decitabine ( 5-aza-2-deoxycytidine ) is a cytosine nucleoside analog that after phosphorylation directly incorporates into dna resulting in inhibition of dna methyltransferases .
the resulting dna hypomethylation causes reversal of abnormal epigenetic silencing of genes critical to normal cellular differentiation , proliferation , and normal cellular life processes such as apoptosis .
it has minimal toxicity and hence is favored in patients who are unable to tolerate standard chemotherapeutic regimens .
our third patient was enrolled in a trial utilizing a short five - day course of decitabine prior to intensive chemotherapy with cytarabine , daunorubicin and etoposide .
she achieved and remained in remission with one cycle of decitabine and one dose of cytarabine without significant hematologic toxicities despite considerable delay in resumption of chemotherapy due to overwhelming infection .
low - dose decitabine ( 20  mg / m / day for 10 days given every 4 weeks ) has demonstrated promising results in children with very high risk relapsed/ refractory aml in whom other treatment options had been exhausted .
three out of eight patients had a complete response , with best responses noted after a median of 2.5 cycles . despite significant comorbidities , decitabine monotherapy demonstrated minimal toxicity .
recently , sequential treatment with decitabine and cytarabine was found to be more effective than cytarabine alone in xenograft models of childhood aml .
relative to studies with heavily pre - treated patients , our patient was chemotherapy naive and had minimal hematologic or other toxicities secondary to chemotherapy .
given the favorable toxicity profile and efficacy in childhood aml , we suggest that decitabine may serve as a bridging anti - leukemic agent during serious illness and reduce risk of recurrence secondary to prolonged treatment delays .
overall , managing concurrent malignancy and critical illness is a delicate balance , one in which decitabine may play a pivotal role ; however further clinical trials are needed .

Answer:
acute appendicitis in children with acute leukemia is uncommon and often recognized late .
 immunocompromised host state coupled with the importance of avoiding treatment delays makes management additionally challenging .
 leukemic infiltration of the appendix though rare must also be considered .
 although successful conservative management has been reported , surgical intervention is required in most cases .
 we present our experience with acute appendicitis in children with acute leukemia and a case of complete remission of acute myeloid leukemia with a short course of decitabine .
 decitabine may serve as bridging therapy in critically ill patients who are unable to undergo intensive chemotherapy .


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:
Investigation of an F-18 oxytocin receptor selective ligand via PET imaging

Paper sections:

Oxytocin was the first endocrine system hormone to be synthesized in the laboratory, and has been studied extensively for its role in the induction of labor and the milk ejection reflex.1 More recently, research foci have been directed toward the role of oxytocin and the oxytocin receptor (OTR) in the regulation of psychosocial behavior.2–10 In addition to being implicated in modulating maternal nurturing and mother–infant bonding, pair bonding, social recognition, increased eye-to-eye contact, trust and empathy, the oxytocin system has also been investigated in relation to disorders characterized by disruption in social behavior, including autism spectrum disorders.11–17 While the bulk of the research conducted with the oxytocin system in humans has been limited to experimental paradigms involving administration of oxytocin followed by behavior monitoring, methodologies implemented for investigating OTR within the brain have been limited to post-mortem receptor autoradiography, in situ hybridization, and gene association studies.12,13,18–21 The development of a methodology permitting the quantification of OTR in the living brain would represent a significant advance in this area of research. Our goal is to develop a positron-emitting small molecule with high affinity and selectivity for the human and primate OTR to enable non-invasive correlations between neural OTR densities and behavior via in vivo positron emission tomography (PET). In addition to this goal, we are simultaneously seeking to discover new candidate pharmaceuticals which may prove useful in reaching OTR specifically within the brain or the periphery for the purpose of potentially alleviating and/or investigating symptoms associated with social behavior disorders. We report here the synthesis, radiosynthesis, and PET imaging evaluation of one of our lead candidate compounds meeting these criteria.

We have recently reported progress in the development of OTR selective ligands bearing radioactive isotopes with some bearing structural similarity to the lead candidate described here.22,23 These molecules were found to either not penetrate the blood–brain barrier or have high affinity for the p-glycoprotein pump which prevented their retention within the brain. We concluded that the lack of a hydrogen bond donor may have been the cause for lack of brain penetration or retention. Therefore, we proceeded to modify the structure by eliminating the methyl sulfonyl group of our former lead candidate, 2, to generate a compound bearing a free amine to act as a hydrogen bond donor, 1 (Fig. 1). The synthetic route was derived from a precursor in our previously reported synthetic pathway, 3, and is outlined in Scheme 122 The free amine of 3 was protected using di-tert-butyl dicarbonate to generate 4. The phenol position of 4 was then alkylated using 1-bromo-2-fluoroethane to provide the fluoroethoxy moiety of 5. A deprotection using 2 M HCl in ether then resulted in the target molecule, 1, as a hydrochloride salt. Further synthetic details and characterizations are provided in the Supplementary data.

To determine if the structural modification resulted in any loss of biological properties, 1 was subjected to in vitro competitive binding assays using cell lines expressing human oxytocin and all known vasopressin receptor subtypes (V1aR, V1bR, and V2R). The results of these assays are displayed in Table 1 with data for 2 obtained from our previously reported study.22 These data indicate the removal of the methyl sulfonyl group actually resulted in a slight improvement of the biological properties. Having a Ki value of 15 nM for the OTR, 1 matched the binding affinity of 2. While the binding affinity of 1 for the V1aR slightly increased, the binding affinity for the V2R decreased significantly in comparison to 2, thus making it slightly more selective overall. Further in vitro binding assays were also performed on 88 other human G-protein coupled receptors (GPCR) in a screen to determine if 1 had affinity for these other receptors. Table 2 contains the results of the screen in which 7 other GPCR had modest to mild affinity for 1, none of which would be expected to display significant uptake during a PET scan. The most notable binding affinity was found in the alpha-1A subtype of the adrenergic receptor and the 6 subtype of the 5-hydroxytryptophan receptor (5-HT6) having a Ki values of 82 nM and 187 nM, respectively. Although these Ki values for the non-target receptors are not believed to be optimal for PET imaging, they would present an issue if 1 was to be considered for pharmaceutical development.

Having good binding affinity and selectivity, the F-18 analogue of 1 was generated for further investigation. The synthetic route to [18F]1 is outlined in Scheme 2. The Boc-protected amine 4 was alkylated with ethane-1,2-diyl bis(4-methylbenzenesulfonate) to generate our tosylate precursor 6. Radiolabeling was then conducted in a CTI-Seimens Chemistry process Control Unit (CPCU) to perform SN2 substitution using the cryptand ligated K222
18F followed by removal of the Boc-protecting group with 1 M HCl. The crude radioactive mixture was eluted from the CPCU unit with a 7 ml solution of ethanol:water:triethylamine (50:50:0.1). Solid phase extraction was then performed to remove excess acid prior to HPLC purification. The extracted mixture was then purified via HPLC and concentrated into a dose form (15 ml solution of 10% ethanol in saline) via solid phase extraction and passed through 1 and 0.2 lm filters using high argon pressure. A dose would normally be prepared in 120 min from the start of synthesis and result in approximately 19% uncorrected yields of [18F]1 with a specific activity greater than 10 Ci/µmol. Radiochemical purity was greater than 99.9%. A representative analytical HPLC graph is shown in Figure 2.

To gauge the probability of brain penetration, the log P7.4 was determined to be 1.57 using previously reported methods. This lipophilicity measurement is within the range of 1–3 estimated to be the calculated optimal range for penetration of the blood brain barrier.24 To evaluate brain penetration in vivo, PET studies were first performed using female 180–200 g Sprague–Dawley rats (n = 4) in the same manner as our previously reported study.22,25
Figure 3 contains representative time activity curves generated from [18F]1 distribution which compares the muscle tissue uptake with whole brain uptake. As can be seen in the graph, there is a burst of activity into the brain at the beginning of the scan which clears after 20 min post injection. Therefore, the first 20 min of the scan were summed to analyze brain uptake. Figure 4 contains representative images of [18F]1 over the first 20 min time span post injection. Uptake appears to be located at areas in and around the cerebral ventricles. However, it is difficult to make a conclusive determination of the exact areas of uptake in the rat due to the size of the subject, small areas of OTR binding in the rat brain, limits of resolution of the PET scanner, and limited time of retained uptake.

To further evaluate [18F]1 in a model which would better represent a human and should be large enough to detect regions of OTR binding with a PET scanner, PET imaging was conducted using [18F]1 in a cynomolgus monkey model. Three types of studies were performed to evaluate the tracer and its distribution within the brain, a baseline scan in which only the tracer was injected, a blocking scan (5 mg/kg of the cold standard was administered 30 min prior to the tracer), and a chase scan (5 mg/kg of cold standard was administered 45 min after the tracer). These procedures were performed on a subject anesthetized with Telazol (3 mg/kg; i.m.) and maintained on a 1–2% isoflurane in pure oxygen mixture while intubated and placed on a ventilator throughout the imaging procedure. A 15 min transmission scan was performed using a germanium- 68 point source to provide attenuation correction. Approximately 5 mCi of [18F]1 was then administered at the start of the emission scan and scanning continued for 2 h. For blocking and chase studies, 5 mg/kg of 1 was administered 30 min prior to [18F]1 injection or 45 min after [18F]1 injection, respectively, via a slow bolus injection.

Figure 5a–c contains images obtained from the sum of the 2 h baseline scan and arrows indicate the uptake found primarily in the ventricles within the brain. One possible site of radiotracer binding within the ventricles is the choroid plexus, which is a highly vascularized network of structures within the ventricles of the brain which synthesizes and recycles cerebrospinal fluid (CSF). The time activity curves of the standard uptake values (SUV) for the ventricular lining, the whole brain, and the muscle tissue obtained from the baseline scan are shown in Figure 6a. The graph suggests significant amounts of [18F]1 reach the brain during the first 500 s of the scan, but as can seen by the concentration of [18F]1 in the ventricular lining during the same timeframe, it could be deduced to account for the bulk of brain activity detected. Therefore, no significant accumulation of the ligand was detected in any sites within the brain. Thus, it could be deduced that [18F]1 did not penetrate the extracellular space of the brain, and only reached the vasculature and the choroid plexus. As can be seen in Figure 5d which sums up the first 15 min of the scan, there is uptake observed at the middle cerebral artery in the sulcus of the outer region of the cerebral cortex near the insula. This may explain the increase in whole brain uptake during the first 500 s of the scan, although we cannot rule out accumulation in the CSF of this region. The time activity curve of the choroid plexus/ventricular lining in Figure 5a clearly demonstrates that [18F]1 binds strongly in this area. Although there have been reports of vasopressin 1a and alpha-1A adrenergic receptors in this region, there are have been no reports of OTR in the choroid plexus.26

To verify if the observed [18F]1 uptake was due to binding to a saturable protein on the cerebral ventricles, blocking and chase scans were performed in which 5 mg/kg of the cold standard, 1, was administered 30 min prior to [18F]1 (blocking) or 45 min post injection of [18F]1 (chase). The comparable time–activity curves are shown in Figure 6b and c, respectively. The blocking study resulted in an increase of overall brain activity, primarily in the region of the choroid plexus. The images obtained were nearly identical to those obtained from the baseline scan and are not shown. The observed increase of [18F]1 after blocking is thought to be due to the blocking of peripheral OTR and perhaps the mild affinity 1 has for the alpha-1 adrenergic receptor (there is a vast distribution of these type of receptors in the periphery). Once the majority of these receptors are blocked in the periphery, it allowed more tracer to become available in the blood, thus increasing the overall activity concentrations in the choroid plexus and vasculature. The inability of 1 to block the uptake of [18F]1 in the choroid plexus would suggest that the uptake is not specific to a saturable protein. However, the chase study afforded completely opposite results. In the chase study, the uptake within the choroid plexus was completely removed after administration of 1 by the end of the remaining hour and 15 min of scan time. When the summed images from the final 30 min of both the baseline and chase scans are directly compared (Fig. 7), it is clearly evident [18F]1 is completely removed by the addition of 1. These results suggest that 1 has some type of affinity equilibrium within the choroid plexus that shifts when additional amounts of 1 are administered. It should be noted that previously investigated PET imaging studies using pharmaceutical derivatives, including our studies with a completely different OTR selective molecule, have shown to have uptake in the choroid plexus region; the phenomenon is not unique to 1.23,27,28

In summary, a very selective OTR ligand, 1, has been investigated in vitro with receptor binding assays and in vivo via synthesis of its positron emitting analogue, [18F]1, and PET. Brain penetration of [18F]1 may be present in the rat, but appears to be limited to the choroid plexus area in both the cynomolgus macaque and the rat. In the cynomolgus monkey, brain penetration appears to be negligible except for specific uptake within the choroid plexus. Neither PET scan suggested [18F]1 will be useful for detecting OTR in vivo. It is possible that the densities of OTR in the cynomolgus monkey model are not high enough to afford a signal via PET using a biomarker with a Ki affinity greater than 1 nM, or that they even do not exist. Indeed, to date, inconclusive results have been reported regarding specific OTR binding in the rhesus macaque brain29 (Young, LJ and Freeman, SM unpublished data). By contrast, we and others have confirmed that the common marmoset has high densities of OTR in the nucleus accumbens.19 Therefore, we will be conducting future investigations utilizing the common marmoset as the model system. We will continue to perform structure/activity studies with derivatives of this candidate compound to increase brain penetrance, increase affinity for OTR will maintaining selectivity, and eliminate binding to the cerebral ventricles.

Answer: The compound 1-(1-(2-(2-(2-fluoroethoxy)-4-(piperidin-4-yloxy)phenyl)acetyl)piperidin-4-yl)-3,4-dihydroquinolin- 2(1H)-one (1) was synthesized and positively evaluated in vitro for high potency and selectivity with human oxytocin receptors. The positron emitting analogue, [F-18]1, was synthesized and investigated in vivo via PET imaging using rat and cynomolgus monkey models. PET imaging studies in female Sprague\xe2\x80\x93Dawley rats suggested [F-18]1 reached the brain and accumulated in various regions of the brain, but washed out too rapidly for adequate quantification and localization. In vivo PET imaging studies in a male cynomolgus monkey suggested [F-18]1 had limited brain penetration while specific uptake of radioactivity significantly accumulated within the vasculature of the cerebral ventricles in areas representative of the choroid plexus.