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:
standard care for chronic hepatitis c ( chc ) has been a combination of pegylated interferon - alpha ( peg - inf ) and ribavirin , although this treatment has suboptimal antiviral efficacy and significant adverse events . even in the latest treatment recommendation using novel direct acting antiviral agents , interferon ( ifn)-based treatments are still optional .
the main drawbacks of interferon - based treatment are unsatisfactory response rate and various adverse effects , which often lead to premature termination of treatment followed by treatment failure .
myasthenia gravis ( mg ) is an autoimmune neuromuscular junction disorder characterized by muscular weakness and fatigability .
mg is occasionally associated with invasive thymoma that needs surgical resection and may progress to severe respiratory failure .
development of mg in patients with chc has been rarely reported before or during antiviral treatment with interferon .
a total of 12 cases of mg were reported in association with interferon treatment for chc and 6 of them went through myasthenia crisis that require respiratory support .
we experienced a rare case of myasthenia crisis during antiviral therapy for chc , in whom mediastinal thymoma was discovered and successfully managed with surgical thymectomy and meticulous medical care .
we reviewed the clinical course of this life - threatening complication of ifn treatment along with the already reported myasthenia crisis cases in chc patients .
a 47-year - old male patient presented with a complaining of sudden diplopia that developed one week after 11-week of antiviral combination treatment for chronic hepatitis c ( figure 1a ) .
he had been on antiviral combination treatment with peg - ifn-2a ( 180  g / wk ) ( pegasys ; roche , basel , switzerland ) and ribavirin ( 1000  mg / d ) ( lg ribavirin ; lg life sciences , seoul , korea ) for the genotype 1b hepatitis c virus ( hcv ) infection .
the pretreatment serum hcv rna level was 2.32    10 iu / ml and ast / alt levels were 255/323  u / l . at 6-week of treatment ,
the dosage of peg - ifn-2a was reduced to 90  g / wk , but wbc count continued decreasing to 2000/mm .
five weeks later , the absolute neutrophil count was 500/mm and the serum hcv rna level was below the limit of detection ( < 15  iu / ml ) .
consequently , the antiviral treatment was promptly discontinued and the neutropenia improved on serial blood tests .
one week after discontinuation of antiviral treatment , the patient complained of sudden diplopia and right eye ptosis was observed .
one week later , right eye ptosis and upper extremities weakness ( grade iii ) were noted . he was immediately hospitalized and initial physical examination was normal except facial palsy with the right ptosis , mild dyspnea , and upper extremities weakness . upon admission , he denied any other oral medications and had no history of vascular or thyroid diseases .
ptosis and restricted movement on the right upper lid was improved after treatment ( b ) .
on further evaluation , the low rate repetitive nerve stimulation test ( jolly test ) and neostigmine test were positive findings for myasthenia gravis ( table 1 ) and serum antiacetylcholine receptor ( anti - achr ) antibody level of 14.95  nmol / l ( normal range : below 0.2
initial symptoms of ocular mg progressed to difficulties in chewing and swallowing , followed by respiratory failure in 3 days .
administration of pyridostigmine ( mestinon ) 180  mg / day was started and chest ct scan was performed which revealed anterior mediastinal mass measuring 7  cm in its greatest dimension , whereas brain imaging study was normal ( figure 2 ) .
the patient received a surgical thymectomy and a high - grade thymoma invading pericardium and pleura ( figure 3 ) was observed on the pathological examination of the surgical specimen , which confirmed invasive thymoma ( type b3 , who classification ) .
the patient 's respiratory failure aggravated after surgery , leading to an increased ventilator dependency . in response to the worsening respiratory condition
, pyridostigmine dose was increased up to 600  mg / d and intravenous immunoglobulin and high - dose steroid pulse therapy were started .
after 40 days of intensive care , the patient has his ocular symptoms back to normal ( figure 1b ) and was successfully weaned from the mechanical ventilator .
results of low rate repetitive nerve stimulation test ( rnst ) and stigmine test chest ct findings .
there was 7-cm sized lobulated solid mass with internal low density and calcified portion at anterior mediastinum .
( a ) h&e stain ( 40 ) shows a multilobular growth pattern and infiltration into lung parenchyma .
( b ) h&e stain ( 100 ) shows thymoma b3 findings : sheet - like growth of medium - size round or polygonal cells with slight atypia ( sheet - like growth pattern ) ; epithelial cells are mixed with a minor component of intraepithelial lymphocytes .
treatment for chc with combination of peg - inf and ribavirin eradicates hcv rna in 40% to 50% of treatment - naive patients infected with hcv genotype 1 . in early clinical trials ,
10% to 14% of treated patients discontinue combination treatment prematurely due to various adverse events and ifn was the major concern in most of them .
unsatisfactory response rate and high rate of unbearable side effects have been the major issues of conventional combination therapy .
recently , direct acting antiviral agents ( daa ) against hcv were developed and showed markedly improved clinical efficacy than the conventional combination treatment in terms of both potency and safety aspects .
new standards of treatments using direct acting antivirals are being established and rapidly replacing the conventional combination therapy . however , the conventional combination treatment is still widely prescribed for chc and ifn is not completely excluded from some of the daa - based new regimens yet .
therefore , for the treatment of chc it is still major concern of clinicians to cope with the various side effects of ifn .
mg in patients with chc were mostly associated with ifn treatment , but it may develop without ifn administration . two case reports   described development of mg in chc patients who did not receive antiviral treatment . a 35-year - old male patients with established chc for several years without any treatment developed mg and a 59-year - old male with liver cirrhosis as a result of long - standing hcv infection developed typical mg symptoms and died due to myasthenia crisis .
the authors suggested the cross - reactivity between hcv epitopes and the acetylcholine receptor as the underlying mechanism .
the etiologic roles of various viral infections including hcv were suggested for the development of mg , but the exact significance of hcv infection per se is not clear .
though mg was not reported in large - scale analyses of chc patients who received ifn treatment , literatures suggesting the association between mg and ifn administration have been published in the form of case reports .
there were 12 cases of mg by ifn for chc including 6 myasthenia crisis cases ( table 2 ) . in case reports of myasthenia crisis that developed during ifn - based antiviral treatment for chc ,
male patients > 44 were most commonly affected and the mean age of patients was 57 years and mean interval between starting ifn administration and diagnosis of mg was 4.57 months ( 6 weeks to 15 months ) .
the mean duration of ifn treatment was 4.96 months ( 6 weeks to 15 months ) .
the mean level of anti - achr antibody was high as 16.3  nmol / l .
in most patients , respiratory distress followed advanced progression of mg symptoms and a case of severe respiratory failure was reported at 6 months after ifn discontinuation .
the clinical courses of mg cases by ifn for chc were either mild or severe enough to suffer myasthenia crisis , but most of the patients were recovered eventually with medical care after discontinuing ifn treatment . list of cases of myasthenia crisis by interferon treatment for chronic hepatitis c to our knowledge , this is the second case of thymoma - associated mg during ifn treatment for chc . a case of mg that progressed to myasthenic crisis was reported at 1996 in japanese patient who had thymomectomy for known thymoma - associated mg , 19 years before starting antiviral treatment .
thymomas are responsible for 21% of mg cases and 30% of patients with thymoma have symptoms of mg .
myasthenic crisis is the most serious complication of mg and thymoma is one of the risk factors attributed to it .
the mechanism of mg development by ifn therapy is not completely understood , but some of the complex immunological actions of ifn such as enhanced lymphocyte cytotoxicity , production of pro - inflammatory cytokines , inhibition of t suppressor cell function , activation of t helper lymphocytes by autoantigens , and differentiation of antigen - presenting cell might contribute to the development of ifn - induced autoimmune diseases .
the thymus plays a primary role in early - onset mg mediated by anti - achr antibodies
. ifn - beta could play a central role in thymic events leading to mg by triggering the overexpression of a - achr probably leading to thymic dendritic cells autosensitization , the abnormal recruitment of peripheral cells , and germinal center formation .
the epithelial neoplastic cells of thymoma are capable of presenting epitopes , which cross - reacts with different neuromuscular antigens .
in addition to achr antibodies , antibodies against striated muscle titin and ryr antigens are found in most of mg thymoma patients . on the other , it has also been suggested that some infectious viruses and hcv itself may lead to mg via mechanism of cross - reactivity between viral epitopes and the acetylcholine receptor .
it is not known whether the patients who experienced mg during ifn treatment for chc had subclinical mg before initiating treatment because pretreatment screening for mg is not routinely recommended . in some patients ,
pre - existing subclinical mg that might be associated with hcv infection itself , progress to overt mg during ifn treatment , whereas , in others , de novo mg might be induced by ifn administration . in our patient , relatively large thymoma
so it seems that thymoma - associated subclinical mg were unrecognized before treatment , which was provoked by ifn administration to progress to life - threatening myasthenic crisis . for the better understanding of clinical implication of ifn - induced mg in chc treatment , screening for mg in chc patient
might be considered before starting treatment or at least , during treatment when the patient complained of fatigue , muscle weakness .
screening for mg with serum anti - achr antibody test is simple and helpful in many patients , but it needs further investigation in this clinical condition because some of mg patients have serum anti - achr antibody levels within normal range .
in patients with chc who is going to receive ifn - based antiviral treatment , whether screening for thymoma or subclinical mg should be included in basal evaluation is not clear but physicians need to keep in mind the potential life - threatening manifestations of mg before and during antiviral treatment especially when patients complain of muscular weakness and easy fatigability .

Answer:
abstractmyasthenia gravis is occasionally associated with thymoma that needs surgical resection and may progress to severe respiratory failure .
 we experienced a rare case of myasthenia crisis during antiviral therapy for chronic hepatitis c , in whom mediastinal thymoma was discovered and successfully managed with surgical thymectomy and meticulous medical care.a 47-year - old - male patient complained of sudden diplopia 1 week after stopping 11-week administration of pegylated - interferon and ribavirin for chronic hepatitis c. ophthalmologic examinations revealed ptosis on the right eyelid and restricted right eye movement .
 myasthenia gravis was confirmed by positive repetitive nerve stimulation test and positive serum antiacetylcholine receptor antibody test , and mediastinal thymoma was found on chest ct scan .
 the ocular myasthenia gravis progressed to respiratory failure even after discontinuing antiviral treatment but eventually recovered with thymectomy , anticholinesterase administration , steroid pulse therapy , and prolonged ventilator care .
 we describe the clinical features of this life - threatening complication of interferon treatment along with previous myasthenia crisis cases by interferon for chronic hepatitis c.in patients with chronic hepatitis c who is going to receive interferon - based antiviral treatment , physicians need to keep in mind the potential life - threatening manifestations of myasthenia gravis before and during antiviral treatment especially when patients complain of muscular weakness and easy fatigability .


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:
myoepithelial carcinoma ( mc ) is a rare tumor with an incidence of 0.2% of all salivary gland tumors . most of the reported cases of mc arise in the parotid gland ( 4875% ) , followed by minor salivary glands , and the submandibular gland .
the first case was described by higashiyama et al . , in 1998 . since then , only seven cases have been reported in literature .
a mentally retarded 13-year - old girl , with a history of congenital hypothyroidism and cystic lymphangioma in the left dorsal region , operated in 2004 , had consulted for cough and dyspnea in september 2010 .
physical examination showed a decrease in vesicular breath sounds at the basal areas of chest bilaterally , without fever .
pulmonary computed tomography ( ct ) showed bilateral pleural masses measuring 6.3 cm and 7.4 cm at the right and left bases , respectively , with lymph node metastases [ figure 2 ] .
( a ) bilateral pulmonary opacities ( b ) disappearance of pulmonary opacities pulmonary computed tomography ( ct ) : bilateral pulmonary masses a histopathological study of the left pleural biopsy revealed a monomorphic proliferation of round cells with clear cytoplasm and a weak , mitotic hyperchromatic oval nucleus [ figure 3 ] .
there were some cohesive layers , separated by bands of sclerosis ; the stroma was sparse with foci of necrosis .
the immunohistochemistry ( ihc ) study was focally positive for vimentin , cd99 , and ps100 .
the abdominal ultrasound , bone scan , and metaiodobenzylguanidine ( mibg ) scintigraphy were normal .
the histopathological and the ihc review at the  institut bergoni  in france concluded the diagnosis of myoepithelial carcinoma of the soft tissues with intermediate malignancy .
ihc was positive for pancytokeratin ( ae1/ae3 ) and ps100 , and negative for ema , cd34 , desmin , and cd99 .
the progression was marked by the disappearance of the pulmonary opacities [ figure 1 ] .
they include mucoepidermoid carcinoma , adenoid cystic carcinoma , acinic cell carcinoma , oncocytoma , epithelial
it arises from the submucosal bronchial glands of the lower respiratory tract . in the world health organization classification , published in 2004 ,
mc was cited as being synonymous with epithelial  myoepithelial carcinoma . as mc and epithelial
myoepithelial carcinoma of the salivary gland are distinguished by the presence or absence of ductal cells , their pulmonary counterparts must also be differentiated .
myoepithelial tumors are low - grade lesions without recurrences or metastasis described after resection , whereas , the rate of metastasis in mc is high , as seen in our case .
our patient represents the first pediatric case , described in the literature , having primitive pulmonary mc .
the tumor was peripheral and bilateral , measuring 6 cm and 7 cm , which was in agreement with the literature .
in fact , the size of the mc ranged from 15 mm to 130 mm ( mean 50.7 mm ) [ table 1 ] . characteristics of pulmonary mc in our case , the histopathological study oriented to the diagnosis of a primitive neuroectodermal tumor or neuroblastoma .
the pathological review , with further ihc analysis in france , had concluded the diagnosis of mc .
the following markers were found to be useful in myoepithelial carcinoma : cytokeratins ( ae1/ae3 ) and vimentin ( reported to be positive in neoplastic myoepithelial cells and negative in normal myoepithelial cells ) .
other variable markers , such as , ps100 , calponin , smooth muscle actin ( sma ) , muscle - specific actin ( msa ) , smooth muscle myosin , and p63 protein , could be positive .
however , neoplastic transformation of myoepithelial cells could result in a loss or a modification of their smooth muscle phenotype . in our case ,
although the eight patients reported in literature were treated with optimal surgery , metastases were reported in seven of them ( 87.5% ) ( contralateral lung , forearm , liver , and brain ) .
it was significant that a patient who had not developed metastasis , had the lowest tumor mitotic rate of 5/10 hpfs .
this fact reasoned that the mitotic rate could be an important prognostic factor of the clinical outcome and survival in primary myoepithelial carcinoma of the lung .
given the rarity of these tumors , recommendations regarding chemotherapy or radiation , either pre- or postoperatively , are difficult to formulate .
the originality of our case is the disappearance of the pulmonary opacity spontaneously , without any treatment .
our case represents , to the best of our knowledge , the first pediatric case having primitive pulmonary mc .
the histopathological study familiarizes the diagnosis , but a further ihc study is needed to confirm the diagnosis and to eliminate other etiologies .
surgery represents the main treatment for the operable forms . to the best of our knowledge ,
we have reported the first case , with spontaneous regression of this tumor , without any treatment .

Answer:
primary myoepithelial carcinoma ( mc ) of the lung is exceedingly rare .
 we report here , to the best of our knowledge , the first pediatric case having primitive pulmonary mc .
 the originality of our case was the disappearance of the pulmonary opacity spontaneously , without any treatment .
 the difficulties in our case were the diagnosis of this rare entity and its subsequent treatment .
 in fact , given the rarity of these tumors , recommendations regarding chemotherapy or radiation , were difficult to formulate .


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:
parosteal lipoma is an extremely rare benign tumor composed mainly of mature adipose tissue with a bony component .
it is among the rarest neoplasias of skeleton , accounting for less than 0.1% of primary bone tumors and 0.3% of all lipomas .
the most common locations for this tumor are the femur , proximal radius , humerus , tibia , clavicle and pelvis .
thought to arise from mesenchymal cells in the periosteum , parosteal lipomas share histopathologic features with the commonly occurring soft - tissue lipomas , and cytogenetic evidence suggests a common histopathogenesis . depending on the degree of chondroid modulation and enchondral ossification , parosteal lipomas may rest directly on the cortex without cartilage or bone elements ; may have a narrow bony stalk with a lucent lipomatous cap , mimicking a pedunculated exostosis ; may have a densely ossified broad - based osteochondromatous element beneath a thin lipomatous cap , simulating a sessile exostosis ; or may have patches of chondroid and bone scattered throughout the lipomatous mass .
this study reports the case of a 65-year old woman with a big mass on the posteromedial aspect of the right upper arm since 1 year ( admitted on 05/07/2013 ) .
the swelling was slow growing , painless , soft , nontender , immobile , with well defined margins and no fixity to skin .
on roentgenogram of right humerus there was an evidence of ill defined soft tissue swelling in the upper arm posteromedially with radiopacity in continuation with the surface of humerus suggestive of bony excrescences ( fig .
mri right shoulder joint ( plain  +  contrast ) revealed a large 13  cm    5  cm    8  cm well defined , nonenhancing , lobulated , heterointense , predominantly fat intensity lesion with a small area of chondroid component measuring 2  cm    1.6  cm in posteromedial aspect of the proximal right humerus , seen completely separate from the adjacent muscles ( fig .
vertical elliptical incision was taken over the posterior border of the right upper arm over the tumor .
the tumor was under the lower part of deltoid which formed the roof near the upper end of humerus , between the long and medial heads of triceps muscles ( fig .
6  cm    5  cm    5  cm sized part of the tumor was under the long head of triceps displacing it medially along with radial nerve and vessels .
7  cm    6  cm    3  cm sized part of tumor was under the medial head of triceps displacing it laterally .
after hemostasis , wound was closed with a suction drain in situ . the specimen ( fig .
5a ) weighed 250  g. postoperatively a shoulder sling was given for 3 weeks to prevent any inadvertent fracture following the use of osteotome over the humerus during the surgery .
1b ) of right humerus was normal and showed no bony excrescences . on gross pathology ,
the lesion was multilobulated , well circumscribed and irregular mass of size 12  cm    5  cm    8  cm with a bony part measuring 2.5  cm    2  cm    1  cm .
5b ) , the lesion was composed of mature lipocytes that had an intimate relationship with the periosteum , consistent with parosteal lipoma .
parosteal lipomas , benign adipose tissue tumors situated directly on bone cortex , are unusual neoplasms that appear to emerge from multidirectional mesenchymal  modulation  within the periosteum .
periosteal lipomas  ,  chondrolipomas of soft tissue  and  lipomas of nerves  but they are most commonly believed to originate from the periosteum .
these tumors are frequently associated with chondroid and/or osseous modulation , which permit subclassification into 4 distinct variants : ( i ) no ossification ; ( ii ) pedunculated exostosis ; ( iii ) sessile exostosis ; and ( iv ) patchy chondro - osseous modulation .
parosteal lipoma presents as an immobile , nontender , slow growing mass over bones that is not fixed to skin .
on radiographs , a parosteal lipoma is a well - defined area of lucency located adjacent to a long bone . in one series of parosteal lipomas ,
60% had definite bony alterations , mostly hyperostotic reactive changes ( fine linear densities , calcification , cortical thickening or undulation , or frank excrescences of bone ) , but these lipomas also have cortical bowing and smooth cortical erosions .
parosteal lipomas have a homogeneous lobulated appearance and are adherent to the surface of the adjacent bone .
when present , osseous excrescences may mimic osteochondromas , but the former lack the contiguity of the marrow space with the underlying bone that is characteristic of the latter .
parosteal lipomas that gain clinical attention are those that compress neurovascular bundles and cause motor and sensory function deficits .
the tumor is identified on mr images as a juxtacortical mass with signal intensity identical to that of subcutaneous fat , regardless of pulse sequence .
heterogeneity in these lesions is invariably present and corresponds to the pathologic components in the lesion .
areas with intermediate signal intensity on t1-weighted images that are high signal intensity on t2-weighted images represent the cartilaginous components in parosteal lipoma .
fibrovascular septa may cause a lobulated appearance of the fat component , with low - signal - intensity strands on t1-weighted images that become higher in signal intensity on the long tr images ( particularly with fat suppression ) .
larger areas of bone production surrounded by the lipomatous components are also well demonstrated with mr imaging .
adjacent muscle atrophy , poorly demonstrated by ct , is identified on mr images as increased striations of fat in the affected muscle and is caused by associated nerve entrapment .
this finding is best appreciated on t2-weighted images because of the decreased signal intensity of normal muscle relative to fat .
finally , mr imaging best demonstrates the relationship of the tumor to the underlying native bone and muscle , and this information is important for surgical planning because parosteal lipoma is usually firmly adherent to the underlying cortex at the site of surface bone production .
pathologically the lesion is usually a multi - lobulated yellowish mass composed of mature adipocytes , and it is well encapsulated with a broad base of attachment to the underlying bone .
microscopically , the fat cells of a parosteal lipoma appear histochemically identical to the adipocytes that are found in the subcutaneous tissues .
there has been no indication to date that this tumor undergoes malignant degeneration , although minimal cellular pleomorphism may occasionally occur .
the treatment of parosteal lipoma is complete surgical resection . in the case with nerve entrapment ,
the tumor must be removed before irreversible muscle atrophy occurs so as to maintain function .
the nerve must also be separated from the parosteal lipoma and care must be taken to spare it during surgical excision . in our case ,
adequate surgical removal of a parosteal lipoma requires either subperiosteal dissection , which is the separation of the lesion from the underlying bone using an osteotome or segmental resection of bone ; this is in contrast to the relatively easy dissection for a soft tissue lipoma lying adjacent to bone .
several cases have shown a malignant transformation having radiological and histological features of benign lipomas together with histologic fields of either malignant fibrous histiocytoma or liposarcoma .
malignant transformation of a lipoma should be suspected when rapid bone destruction is seen in a radiolucent lipoma .
parosteal osteosarcomas and well - differentiated liposarcomas ( wdlps ) of soft tissue share several features : they are slowly progressive , locally aggressive tumors , tend to recur locally , and rarely or never metastasize if not dedifferentiated .
microscopically , both are well differentiated tumors , very like their normal tissue counterpart . a biopsy is required from its two components , i.e. bony base and peripheral fat .
written informed consent was obtained from the patient for publication of this case report and accompanying images .
dr . rohan chaudhary performed the study design , data collections , data analysis , writing and he was the operating surgeon .

Answer:
introductionparosteal lipoma is an extremely rare benign tumor composed mainly of mature adipose tissue with a bony component.presentation of casethis study reports the case of a 65-year old woman with a big mass on the posteromedial aspect of the right upper arm since 1 year .
 the swelling was a slow growing , painless , nontender , immobile mass which was not fixed to skin .
 she had no complaints of painful or restricted movements of the shoulder joint .
 she had no history of trauma to the upper limb.mri revealed a large 13  cm    5  cm    8  cm well defined , nonenhancing , lobulated , heterointense , predominantly fat intensity lesion with a small area of chondroid component measuring 2  cm    1.6  cm in posteromedial aspect of proximal right humerus , seen completely separate from the adjacent muscles.discussionthe patient underwent surgery under general anesthesia .
 vertical elliptical incision was taken over the posterior border of the upper arm over the mass .
 the tumor was below the lower part of deltoid near the upper end of humerus , which formed the roof , and between the long and medial heads of triceps muscles .
 a part of tumor , measuring 6  cm    5  cm    5  cm , was under the long head of triceps displacing it along with radial nerve and vessels medially while the other part , measuring 7  cm    6  cm    3  cm , was under the medial head of triceps displacing it laterally .
 the tumor was excised undocking its periosteal attachment .
 the specimen weighed 250  g. on histopathology , the lesion was composed of mature lipocytes that had an intimate relationship with the periosteum .
 no cellular atypia or lipoblasts were seen.conclusionparosteal lipomas are rare neoplasias with no proven malignant potential .
 these tumors can be resected without much damage to the adjacent structures , thus preserving the function of the upper limb .


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:
it is the most common endemic mycosis in the united states.1 it is most prevalent around the valleys of the mississippi and ohio rivers.2 in endemic areas , 50%80% of people have evidence of previous exposure to histoplasma.3 the fungus grows as a mold in the soil and when its microconidia are inhaled , causes infection and grows as a yeast in the host tissues .
most infected people remain asymptomatic or complain of a self - limiting flu - like illness .
up to 25% of people infected with human immunodeficiency virus will develop disseminated histoplasmosis , with considerable morbidity and mortality.3 infection outside endemic areas and atypical presentations represent a diagnostic challenge .
we present a case of progressive disseminated histoplasmosis manifesting as a wasting syndrome with hypercalcemia , mimicking a metastatic cancer .
a 65-year - old , type 2 diabetic man presented with a 2-month history of constipation , polyuria , and unexplained weight loss of 54 lb .
he had lived in west pennsylvania until 13 years earlier , when he had moved to the texas panhandle area where he presented with the above complaints . on physical examination ,
laboratory test results revealed a hemoglobin of 10.6 ( normal range 1216 ) g / dl and a white blood cell count of 3.5  10 cells / l ( normal range 4.010.6  10 cells / l ) .
biochemistry tests showed a creatinine of 3.2 ( normal range 0.51.4 ) mg / dl , serum calcium of 12.4 ( normal range 8.410.3 ) mg / dl , and albumin of 3.5 ( normal range 3.75.1 ) g / dl .
the patient s parathyroid hormone level was low at 6 ( normal range 11.054.0 ) pg / ml and serum protein electrophoresis showed a normal pattern .
body computed tomography showed bilateral adrenal enlargement and a mass lesion at the base of the tongue ( figure 1 ) .
magnetic resonance imaging of the brain showed three left - sided brain lesions ( figure 2 ) .
biopsies of the tongue lesion and the left adrenal gland showed necrotizing granulomas containing budding yeast forms , consistent with histoplasmosis ( figures 35 ) .
histoplasmosis is rarely diagnosed in the texas panhandle area and we were unable to tell whether his presentation represented a reactivation of an old infection or progression of a newly acquired infection .
after adequate intravenous hydration , the patient s kidney function tests and serum calcium level reverted to normal .
the patient received a 4-week course of liposomal amphotericin b and was subsequently started on itraconazole .
dissemination of h. capsulatum is common in the early stages of this fungal infection.1 symptomatic acute dissemination develops in immunocompromised patients.2 they present with a febrile illness that can be complicated by severe sepsis , acute respiratory distress syndrome , and disseminated intravascular coagulopathy . on the other hand , chronic progressive disseminated histoplasmosis
is typically reported in middle - aged and elderly men who are not immunosuppressed.3 they present with a wasting syndrome , long - standing fever , and night sweats .
the infection may involve multiple organ systems , including the gastrointestinal tract ( with resulting ulceration ) , adrenal glands ( precipitating adrenal insufficiency ) , the reticuloendothelial system ( causing hepatosplenomegaly ) , bone marrow ( leading to pancytopenia ) , the central nervous system , and the lungs . on rare occasions ,
progressive disseminated histoplasmosis has been associated with hypercalcemia , and this is attributed to increased 1 , 25 dihydroxyvitamin d production from the fungal granulomas.410 a medline search ( january , 1946 to november , 2012 ) identified seven reported cases of disseminated histoplasmosis presenting with hypercalcemia .
the clinical presentation , risk factors that predisposed to histoplasmosis , and patient outcomes are reported ( table 1 ) . upon reviewing the cases and in comparison with the case at hand , the following features were noted . like our patient , most patients were middle - aged and elderly men with a limited degree of immunosuppression .
presenting symptoms varied , with pulmonary complaints in two cases , gastrointestinal symptoms in two , wasting syndrome in three , including ours , and musculoskeletal complaints in another .
hypercalcemia was symptomatic in some cases and an asymptomatic laboratory abnormality in others . in all cases ,
the diagnosis was difficult to make , and in three cases was established post mortem .
two of the three patients who died , ie , the first and second cases , did not receive antifungal therapy , and treatment was delayed in the third patient who died , ie , the fourth case .
diagnosis of histoplasmosis relies on a multifaceted approach.11 histopathological examination , cultures , antigen and antibody detection , and molecular methods are commonly used in different combinations to establish the diagnosis .
a recent multicenter study evaluated the above - mentioned tests in the diagnosis of disseminated histoplasmosis and reported their corresponding sensitivities , ie , 74% for cultures , 76% for histopathology , 92% for antigen detection in urine and/or serum using a third - generation enzyme immunoassay , and 75% for antibody detection combining immunodiffusion and complement fixation assays.11 use of molecular methods in the diagnosis of histoplasmosis has been reported , but remains uncertain and is awaiting further study.12 the high sensitivity of antigen detection is plagued by significant cross - reactivity with other fungal antigens .
cross - reaction occurs in 90% of patients with blastomycosis and in 60% of patients with coccidioidomycosis.13 testing both urine and serum yields better sensitivity .
furthermore , testing cerebrospinal fluid and bronchoalveolar lavage fluid might improve sensitivity in diagnosing central nervous system and pulmonary infections.14 it is worth mentioning that failure to detect histoplasma antigens does not rule out the diagnosis , and repeating the test in patients with progressive illness should be considered.3 severity of illness dictates antifungal treatment options and duration of therapy . for moderate to severe infection , liposomal amphotericin b for 12 weeks followed by a 12-month course of itraconazole is recommended.15 for milder cases , itraconazole for one year is indicated .
for histoplasmosis of the central nervous system , liposomal amphotericin b for 46 weeks followed by itraconazole for at least one year and until cerebrospinal fluid abnormalities and antigenemia or antigenuria resolve is recommended.15 antigen levels in serum or urine should be measured during therapy for progressive disseminated histoplasmosis and central nervous system infection , and for 12 months afterwards .
ten percent to 15% of patients experience a relapse.16 diagnosis and treatment in this group of patients follows the above outlined principles , but also includes long - term itraconazole maintenance therapy .
our work has some limitations , not the least of which is the fact that it is a single case report .
furthermore , the diagnosis was based on a compatible clinical presentation and histopathological examination that could not be confirmed by culture , serology , or antigen detection .
further research is needed to develop readily available tests , probably molecular diagnostic methods , with higher sensitivity and specificity to diagnosis histoplasmosis as well as other mycosis .
acute disseminated infection presents with a sepsis syndrome , whereas chronic dissemination presents as a wasting syndrome .
we reported here a case of chronic disseminated histoplasmosis presenting with multiple mass lesions , weight loss , and hypercalcemia , mimicking metastatic cancer .
in addition to malignancy , granulomatous disease , including fungal infection , should be considered in patients with similar presentation .

Answer:
histoplasmosis is a common endemic mycosis
 . the majority of infections involving this dimorphic fungus are asymptomatic .
 manifestations in symptomatic patients are diverse , ranging from flu - like illness to a more serious disseminated disease .
 we present here a case of chronic disseminated histoplasmosis mimicking a metastatic cancer .
 we reviewed the literature for cases of disseminated histoplasmosis presenting with hypercalcemia , focusing particularly on clinical presentation , risk factors predisposing for fungal infection , and outcome .
 we report a case of a 65-year - old diabetic male who presented with unexplained weight loss and hypercalcemia .
 multiple brain space - occupying lesions and bilateral adrenal enlargement were evident on imaging studies .
 biopsies showed caseating granulomas with budding yeast , consistent with histoplasmosis .
 the patient s symptoms resolved after liposomal amphotericin b and itraconazole therapy .
 granulomatous diseases , including fungal infections , should be considered alongside malignancies , in patients with similar presentation .


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:
dissemination and implantation of gastrointestinal malignancies throughout the peritoneal cavity result in peritoneal carcinomatosis ( pc ) , which is the second most frequent cause of death in colorectal cancer after metastatic disease to the liver . in 25% of colorectal cancer cases ,
the peritoneal cavity is the only site of metastatic disease . despite recent advances in the development of systemic chemotherapeutic agents , pc
attempts have been made in the past decades to increase long - term survival in patients with pc by combining cytoreductive surgery ( crs ) to remove visible disease and hyperthermic intraperitoneal ( ip ) chemotherapy ( hipec ) to eradicate microscopic viable residual disease , with elevated and persistent drug concentration in the peritoneal cavity .
the peritoneal route of chemotherapy administration has the advantage of delivering the agent to the entire peritoneum after all adhesions have been lysed and before they have the opportunity to reform .
the peritoneal - plasma division concept allows a tenfold higher concentration of the chemotherapy to be reached in the abdominal cavity in direct contact with residual cancerous cells while minimal systemic absorption and adverse effects are expected .
the addition of hyperthermia results in a potentiation of cytotoxicity , improving its capability of penetration into tumoral masses   and serving to rewarm the patient after a significant open procedure .
the ideal ip chemotherapeutic agent should be one that has maximal efficacy , offering optimal regional therapeutic benefits , while minimizing systemic toxicity .
mitomycin c ( mmc ) has been the most frequently used ip chemotherapy for gastrointestinal malignancies . the high molecular weight of mmc limits its systemic absorption and toxicity after ip administration .
more recently , based on the efficacy of new systemic agents for patients with metastatic colorectal cancer , oxaliplatin and irinotecan have emerged as good options for peritoneal perfusion [ 6 , 7 ] .
although there are no randomized trials comparing mmc with oxaliplatin as ip chemotherapy , a retrospective study with 539 patients with pc associated with colorectal cancer showed that both agents achieve similar median overall survival ( 32.7 vs. 31.4 months ; p = 0.925 ) .
however , due to shortage of mmc in brazil , we have been using oxaliplatin as the preferred agent . despite all those potential benefits associated with crs with hipec , morbidity and mortality rates are substantial .
large series of patients undergoing crs with hipec report mortality rates ranging from 1 to 8% [ 9 , 10 , 11 , 12 , 13 ] . in the only randomized study ( n = 105 ) comparing systemic chemotherapy ( fluorouracil - leucovorin ) with or without palliative surgery with aggressive crs with hipec , followed by the same systemic chemotherapy regime , the mortality rate in the crs with hipec group was 8% .
in addition , surgical morbidity , such as postoperative ileus , anastomotic fistula , and wound infection , as well as medical morbidity , including pharmacological toxicity , cytopenia , bone marrow aplasia , renal toxicity , and hydroelectrolytic disorders , are quite frequent following crs with hipec [ 3 , 9 ] .
the most common reported complications include enteric fistula , intraabdominal abscess , pneumonia , small - bowel obstruction , pancreatitis , and neutropenia which often prolong the hospital stay . to the best of our knowledge ,
, we describe the case of a previously healthy young man who underwent crs with hyperthermic ip oxaliplatin and developed one episode of tonic - clonic seizure on the second postoperative day .
a 26 year - old man presented in mid-2011 with increasing abdominal pain . in october 2011
he was found to have a poorly differentiated adenocarcinoma of the transverse colon with multiple peritoneal implants .
it was consistent with a pt4 pn2 ( 4/28 ) pm1 colonic adenocarcinoma , kras wild - type . from january to july 2012
, he received 12 cycles of folfiri ( folinic acid , 5-fluorouracil , and irinotecan ) plus bevacizumab at another institution and achieved complete clinical response . at that time
a pet - ct scan revealed lesions with increased fdg uptake in the peritoneum as well as in the colonic anastomosis . from june 2014 to june 2015 , he received 24 cycles of folfiri and cetuximab with initial response followed by stable disease . in september 2015 , he was first seen at our institution and , during a multidisciplinary meeting , it was decided to pursue crs with hipec ( oxaliplatin 300 mg / m ) , which was started on october 5 , 2015 . on the second postoperative day , the patient developed one episode of generalized tonic - clonic seizure which lasted for approximately 2 min .
he was started on phenytoin to prevent new episodes of seizures during the postoperative period .
on october 15 , due to no recurrence of seizures , the anticonvulsant was discontinued .
he stayed at the icu for only 72 h and had the first bowel movement 6 days after surgery . on the 7th postoperative day
, he developed fever with no identified origin and was started on piperacillin - tazobactam and vancomycin . at this time , the patient was also complaining of left scrotal pain and swelling .
an ultrasound of the testis was performed on october 17 and showed normal testicles and increased volume of the left epididymis with heterogeneous echogenicity .
in addition , analysis of the epididymal waveform revealed a low - resistance pattern suggestive of acute epididymitis . despite all cultures having remained negative ,
it was decided to switch antibiotics to amikacin for 10 days and to doxycycline for 14 days and treat the symptoms as infectious epididymitis .
the patient was discharged home on october 22 , 2015 , to complete antibiotics at the outpatient unit .
. ten percent of adults experience a seizure some time during their life . each year , 300,000 people experience a first epileptic seizure ; most of them are younger than 18 years old .
seizures result from a shift in the normal balance of excitation and inhibition within the central nervous system as well as from abnormal brain function .
studies indicate that 2530% of first seizures are  acute symptomatic or  provoked by a brain insult or a metabolic / toxic disturbance of brain function .
provoking factors include fever , head injury , excessive alcohol intake , withdrawal from alcohol or drugs , hypoglycemia , electrolyte disturbance , brain infection , ischemic stroke , intracranial hemorrhage , and proconvulsive drugs ( such as clozapine , maprotiline , tramadol , theophylline , and baclofen ) .
there are several alterations in the physiology of patients during crs and the administration of hipec .
the body temperature increases significantly due to hipec , they experience transient hyperglycemia secondary both to stress from surgery and hyperthermia , as well as the presence of dextrose in the perfusate .
however , none of those abnormalities has ever been reported to cause seizures , as seen in our case .
there are no published articles regarding neurological complications such as seizures in patients who were submitted to hipec with oxaliplatin .
there is , however , one case report of a 37-year - old female patient with a previous history of seizure disorder who underwent crs and hipec with mmc without intraoperative complications and developed signs and symptoms of cerebral edema 4 h after the operation was completed .
she eventually died of cerebral edema , with no established etiology . despite a normal eeg , it was hypothesized that crs with hipec could have caused unrecognized partial complex seizures leading to acute cerebral edema .
even though our patient had no history of seizure disorder , it is a possibility that the seizure threshold may have been lowered secondary to the stress of surgery and hyperthermia .
in fact , seizures are a rare side effect of intravenous oxaliplatin , which are usually associated with posterior reversible leukoencephalopathy syndrome ( pres ) .
pres is characterized by neurologic symptoms such as headache , altered mental status , visual disturbances , and seizures with typical lesions on neuroimaging shown as bilateral , subcortical , symmetric , and vasogenic edema . however , our patient had no symptoms or radiologic findings of pres .
there is a published case of a previously healthy man with mixed adenoneuroendocrine carcinoma who had seizures after the third and fourth cycles of intravenous folinic acid , 5-fluorouracil , and oxaliplatin ( folfox ) with no signs of pres .
after the chemotherapy regimen was switched to folfiri , he never had another event . in this case , the authors attributed the seizures to the intravenous oxaliplatin .
our patient had no electrolyte abnormalities , no signs of infection , brain structural alteration , or other metabolic disorder that could possibly explain the single episode of seizure .
therefore , it may be possible that the seizure was caused either by the physiological modifications that occurred during hipec or by ip oxaliplatin .
because of the increasing use of crs with hipec as an option to treat selected patients with pc , it is important to report those postoperative complications .
this article reports an unprecedented case of seizure in a previously healthy patient who underwent crs with ip oxaliplatin due to metastatic colon adenocarcinoma . despite this being a rare case ,
the corresponding author acknowledges that she is responsible for complying with ethical requirements and declares that the patient was correctly informed , and written informed consent was obtained ; the confidentiality of the patient was strictly preserved .
the patient was informed about the submission of the manuscript and will be acquainted when the article is published .

Answer:
cytoreductive surgery ( crs ) with hyperthermic intraperitoneal ( ip ) chemotherapy ( hipec ) is believed to improve outcomes in well - selected patients with peritoneal carcinomatosis . however , morbidity and mortality rates associated with this procedure are substantial . here
 , we describe the case of a previously healthy young man who underwent crs with hyperthermic ip oxaliplatin and developed one episode of tonic - clonic seizure on the second postoperative day .


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 bacteria , the number of characterized small , noncoding rnas ( srnas ) that have intrinsic functions as regulators has steadily increased in recent years .
many srnas act by posttranscriptionally regulating mrnas via basepairing interactions ( 1 ) . in escherichia
coli , all of the srnas that act by basepairing affect either the stability or translation of the mrna target . in most cases ,
the mrna targets of srna regulation are trans - encoded , and the srna : mrna basepairing interactions are interrupted by gaps in the pairing .
further , most srnas in this class bind to the rna chaperone hfq , which has been shown to facilitate the interaction between many srnas and their targets ( 2 ) . here
, we describe a program , targetrna , which can effectively predict mrna targets of basepairing srnas .
while a number of approaches have been described for identifying targets of microrna genes in eukaryotes ( 37 ) , there have been relatively few computational tools developed for characterizing targets of srna regulators in bacteria .
( 8) describe one such tool , which has been applied successfully in the genome of listeria monocytogenes , though the program is not available as a webserver .
vogel and wagner ( 9 ) offer a comprehensive review of approaches , both computational and experimental , for identifying targets of bacterial srnas .
the program we describe here , targetrna , is accessible via a webserver that has been operating and publicly available since 2005 , processing approximately 1000 sequence submissions per month .
the webserver consists of a 16 cpu parallel computing cluster , and targetrnas underlying search algorithm has been designed for parallel computation , in order to increase performance and to process efficiently a large number of sequence submissions .
the predictive performance of targetrna has been validated experimentally in e. coli using both northern blot and microarray experiments ( 10 ) .
additionally , predictions from targetrna have been validated in other organisms , such as in vibrio cholerae ( 11 ) and in neisseria meningitidis ( 12 ) , or are consistent with experimentally validated interactions , such as in salmonella ( 13 ) .
targetrna takes , as input , a genomic sequence that may correspond to a srna gene .
targetrna then searches each annotated message in the user - specified genome for mrnas that evince statistically significant basepair - binding potential to the input srna sequence .
basepair - binding potential of a srna with each mrna is determined using one of two user - selected hybridization scoring methods .
a detailed description of the hybridization scoring methods has been described previously ( 10 ) . in summary ,
 waterman dynamic program ( 14 ) , except that instead of assessing homology potential , basepairing potential is assessed .
the stacked basepair model of hybridization scoring is based on stacking and destabilizing energies of interacting sequences .
the stacked basepair model calculates the minimum free energy of hybridization for two rna sequences , without allowing intramolecular basepairings .
this model for hybridization scoring closely follows that developed and used for the rnahybrid algorithm ( 7 ) .
the stacked basepair model is computationally more intensive than the individual basepair model and , as a result , increases the time required for calculating basepair binding potential by a factor of approximately five for most sequence inputs .
once targetrna determines hybridization scores for the srna sequence with each message in a genome , the statistical significance of each potential srna : mrna interaction is assessed .
determination of statistical significance is similar to that described for the rnahybrid algorithm ( 7 ) .
ten thousand random rna sequences are generated such that the nucleotides in the random sequences are drawn from the distribution of nucleotides in the actual mrna search space .
the hybridization score is computed for each of these random sequences and the srna sequence .
the resulting distribution of ten thousand hybridization scores is used to estimate a p - value for an srna : mrna hybridization score by determining the probability of observing a score , by chance , equal to or less than the given srna : mrna hybridization score . after computing the statistical significance of basepair binding between a srna sequence and each message in a genome , targetrna outputs a ranked list of mrnas in a genome
whose basepair - binding potential with the srna sequence meets a significance threshold ( the default is a p - value  0.01 ) .
messages with statistically significant basepair - binding potential are considered candidate targets of srna regulation .
figure 1 illustrates example output from targetrna when searching for mrna targets of the srna gene spot42 in e. coli ( 15 ) . as shown in figure 1 , targetrna outputs , for each candidate mrna target identified , an annotation of the mrna , a visual representation of its predicted basepair binding with the srna , and a p - value corresponding to the significance of the hybridization score of the predicted srna : mrna interaction . to facilitate further investigation of candidate message targets , each identified target
is linked to the entrez gene database ( 16 ) from the national center for biotechnology information .
the time required for targetrna to process an input sequence and generate results depends on the length of the sequence and the parameter selection but typically takes only a few seconds .
output from targetrna is available via both a formatted web page and a text file .

figure 1.the figure illustrates example output from using the targetrna webserver with default parameter settings to search for message targets of the srna spot42 in escherichia coli . in the middle of the figure , the six message targets predicted by targetrna are summarized . in the bottom of the figure ,
the predicted interaction between spot42 and one of the six predicted targets , galk , is illustrated .
the predicted interaction between spot42 and galk consists of 41 nucleotides ( from nucleotide 21 to 61 ) in the 109 nucleotide srna spot42 , and 39 nucleotides ( from 19 nucleotides upstream of the galk start codon to 20 nucleotides downstream in the galk coding sequence ) in the galk message .
the figure illustrates example output from using the targetrna webserver with default parameter settings to search for message targets of the srna spot42 in escherichia coli . in the middle of the figure ,
the six message targets predicted by targetrna are summarized . in the bottom of the figure ,
the predicted interaction between spot42 and one of the six predicted targets , galk , is illustrated .
the predicted interaction between spot42 and galk consists of 41 nucleotides ( from nucleotide 21 to 61 ) in the 109 nucleotide srna spot42 , and 39 nucleotides ( from 19 nucleotides upstream of the galk start codon to 20 nucleotides downstream in the galk coding sequence ) in the galk message .
the targetrna webserver provides a number of advanced search options that allow users more flexible control over the target search space beyond that provided by the default parameter settings .
targetrna provides the option of automatically identifying and removing the region of the srna sequence corresponding to the terminator stem - loop since , in many cases , the terminator stem - loop does not participate in the srna : mrna interaction .
users have the option of focusing their search around the 5 utr or 3 utr of messages , specifying the number of nucleotides to include upstream and downstream of the messages start codon or stop codon .
specifying regions around the 5 utr to be searched may be advantageous since many documented target interactions occur in particular regions , such as around the ribosome - binding sites , of messages .
a seed , which corresponds to a minimum required length for at least one stretch of consecutive basepaired nucleotides in the srna : mrna interaction , can also be specified .
the seed is meant to reflect , biologically , the initial interaction between srna and mrna , which has been shown in some cases to be a stretch of unpaired nucleotides in a loop of the srna that first basepairs with the target message . while targetrna searches each annotated message in a genome by default , users have the option of searching an individual message in order to explore more carefully a particular interaction predicted by targetrna .
when searching for targets of a srna in a given organism , targetrna also offers the option of calculating the hybridization scores of orthologous targets with orthologous srnas in other organisms .
since many srna genes are conserved across related species , the program can thus suggest whether it is likely that the targets and hybridization interactions are conserved .
the various user - adjustable program parameters have the benefit of allowing a user to explore the tradeoff between sensitivity and specificity when assessing results of the targetrna program .
for instance , removing the srna terminator sequence , focusing searches for targets to regions around translation start sites of messages , and setting a seed threshold above about five nucleotides can eliminate many false positive predictions .
however , too much stringency with these parameters may result in a lack of identification of true targets .
for example , some srna : mrna interactions include the terminator sequence of the srna , such as the oxys : fhla interaction ( 17,18 ) in e. coli , and some srnas interact with messages somewhat distant from the message 's start of translation , such as dsra ( 19 ) and rpra ( 20 ) when interacting with rpos in e. coli .
thus , the default parameter settings provide only a starting point for message target investigation .
default parameter settings were determined by optimizing performance of targetrna on srna : mrna interactions in e. coli reported prior to 2005 .
considering the recent growth in the number of srna : mrna interactions reported in the literature across a range of bacterial species , we have revisited the issue of whether different default parameter settings would improve the performance of targetrna .
when accounting for a broad set of srna : mrna interactions in different species , we did not find a set of parameters that led to significant improvement , over the current default parameter settings , in successfully identifying targets of srna regulation .
a recent addition to the targetrna webserver is a companion program to targetrna called rnatarget , which provides  reverse searching capabilities . whereas targetrna takes as input the sequence of a candidate srna region and searches the genome for possible message targets , rnatarget takes as input the sequence of a candidate message target of an unknown srna regulator and searches the genome for regions containing possible srna regulators of the target sequence .
rnatarget searches all intergenic sequences greater than 50 nucleotides in length in the genome for regions that evince significant basepair - binding potential to the input candidate target sequence .
rnatarget outputs a ranked list of intergenic regions in the genome whose basepair - binding potential with the target sequence meets a significance threshold ( the default is a p - value  0.01 ) .
intergenic regions with statistically significant basepair - binding potential are considered as candidate regions corresponding to a srna regulator .
figure 2 illustrates example output from rnatarget when searching intergenic regions for candidate srna regulators of the mrna target galk in e. coli .
it has been reported previously that the srna spot42 , which resides in the intergenic region of the genome between genes pola and yiha , interacts with and regulates galk ( 21 ) . as shown in figure 2 , rnatarget outputs , for each intergenic region identified , the flanking protein - coding genes , a visual representation of the predicted basepair binding between the two genomic sequences , and a p - value corresponding to the significance of the hybridization score of the predicted mrna : srna interaction .
it is worth noting that rnatarget searches only for genomic regions demonstrating basepair - binding potential to the target sequence , it does not attempt to identify other properties of genomic sequences suggestive of srna genes , such as transcription initiation or termination sequences .
several other computational programs are available for predicting srna genes in a genome based on various sources of evidence , including transcription signals and comparative genomics information ( 22 ) .

figure 2.the figure illustrates example output from using the rnatarget program with default parameter settings to search for intergenic regions in e. coli that evince basepair binding potential with a region of the galk message around its ribosome binding site .
( b ) details of the predicted interaction between galk and one of the intergenic regions , between genes pola and yiha , is shown .
the srna spot42 , which resides in this intergenic region , is known to interact with and regulate galk ( 21 ) .
the predicted interaction between the intergenic region and galk consists of 41 nucleotides ( from nucleotide 167 to 207 ) in the 380 nucleotide pola
yiha intergenic region , and 39 nucleotides ( from 19 nucleotides upstream of the galk start codon to 20 nucleotides downstream in the galk coding sequence ) in the galk message .
the figure illustrates example output from using the rnatarget program with default parameter settings to search for intergenic regions in e. coli that evince basepair binding potential with a region of the galk message around its ribosome binding site .
( b ) details of the predicted interaction between galk and one of the intergenic regions , between genes pola and yiha , is shown .
the srna spot42 , which resides in this intergenic region , is known to interact with and regulate galk ( 21 ) .
the predicted interaction between the intergenic region and galk consists of 41 nucleotides ( from nucleotide 167 to 207 ) in the 380 nucleotide pola
yiha intergenic region , and 39 nucleotides ( from 19 nucleotides upstream of the galk start codon to 20 nucleotides downstream in the galk coding sequence ) in the galk message .
targetrna is a freely available webserver that predicts message targets of srna action in bacteria .
assessment of targetrna 's performance suggests that the predictive performance of targetrna varies between srnas .
for some srna regulators where one or more targets have been reported in the literature , targetrna successfully identifies the majority of targets , whereas for other srna regulators with one or more targets , targetrna identifies few , if any , targets ( 10 ) .
targetrna operates under the assumption that the basepair - binding potential of two genomic sequences , corresponding to an srna and a mrna target , can serve as a predictor , albeit imperfect , for the interaction of the two rnas .
conserved basepair - binding potential of two genomic sequences across different genomes can provide further evidence for srna : mrna interaction .
however , other factors that may contribute to srna : mrna interactions , such as rna secondary structure or the role of hfq , are not modeled by the program . as more examples of srna : mrna interactions are reported across a range of bacteria , we will gain a better understanding of the various rna properties and components within the cell that contribute to the interactions , and computational methods that aid in investigation of these interactions can be evolved appropriately to incorporate the new insights .

Answer:
many small rna ( srna ) genes in bacteria act as posttranscriptional regulators of target messenger rnas . here
 , we present targetrna , a web tool for predicting mrna targets of srna action in bacteria .
 targetrna takes as input a genomic sequence that may correspond to an srna gene .
 targetrna then uses a dynamic programming algorithm to search each annotated message in a specified genome for mrnas that evince basepair - binding potential to the input srna sequence .
 based on the calculated basepair - binding potential of each message with the given srna regulator , targetrna outputs a ranked list of candidate mrna targets along with the predicted basepairing interaction of each target to the srna .
 the predictive performance of targetrna has been validated experimentally in several bacterial organisms .
 targetrna is freely available at http://snowwhite.wellesley.edu/targetrna .


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:
progressive neurologic deterioration or back and leg pain in children with a history of myelomeningocele ( mmc ) surgery may be due to cord tethering or growth of an intradural inclusion tumor .
loss of motor function in the lower extremities , gait abnormality , back or leg pain , scoliosis , and foot deformity are common findings in postsurgical tethering .
here , we report a child who developed progressive neurological deterioration and severe back and leg pain subsequent to large infected dermoid tumor extending underneath the skin to the spinal canal and intramedullary area .
a 3-year - old boy was referred to neurosurgical department because of severe back and leg pain and motor regression .
he was a known case of lumbar mmc and was operated at 8 months of age .
he could sit at 11 months of age and stand at age of 2 years on his knees , but could not move the distal part of his legs at all .
his back pain had started 3 months ago , which was severe at night and made him unable to sit .
subsequently , he experienced severe leg pain , which prevented him from moving the proximal part of his lower extremities and his mother faced difficulty while cleaning him after urination or defecation . on physical examination , the child was afebrile , but very irritable , with good mental performance , and normal neurological examination of upper limbs .
both lower extremities had lost any movement in proximal and distal parts ( 0/5 ) .
a small tender bulging was identified in his back under the mmc repair incision for one week before admission , but no dermal sinus was found inside or around the incision . spinal magnetic resonance imaging ( mri )
was performed one month before surgery , which revealed cord tethering ( cord at l4- l5level ) .
distal cord was attached to a mass , which was isointense in t1- and hypointense in t2-weighted images .
it was extending from distal cord through the bony defect to the extraspinal canal space .
the cord was dilated from the level of tethering to l1level with a lesion , which was isointense to hypointense in t1- and hyperintense in t2-weighted images , dissimilar to the intensity of cerebrospinal fluid [ figures 1 and 2 ] .
notice the hypointense signal inside the expanded cord compatible with infected dermoid tumor found during surgery hypointense mass in t2-weighted image is extending from distal cord through the bone defect to the extraspinal canal space and the prior mmc surgery field the child underwent surgery with the suspicion of tethered cord associated with an inclusion tumor .
in the prone position , the prior midline vertical incision was opened . during the dissection of subcutaneous tissue ,
dura mater , cord and dermoid tumor were attached to each other at the depth of previous surgical field , and the tumor was extending from the extraspinal area to the intramedullary space between l4 and l1 vertebral levels .
microsurgical release of all intradural adhesions was performed to achieve circumferential untethering of spinal cord associated with gross total resection of intramedullary mass .
complete excision of the dermoid cyst and capsule were performed , which was followed by primary closure of the dura .
on histopathological examination , specimen had the characteristic features of a dermoid cyst , with simple squamous epithelium , hair follicles , and cholesterol - containing debris .
he could move proximal part of his lower extremities with score of 1 - 2/5 , but was unable to stand on his knee as he could do before .
children with mmc are born with a wide range of neurological deficits that will remain after primary repair of lesion .
any new changes in the previous neurological , urological or orthopedics status warrant an extensive investigation to rule out the possible causes , especially tethered cord syndrome .
tethered cord is a common complication following mmc surgery , which may be found in most patients when they are evaluated with spinal mri , but symptomatic tethering occurs only in 10 - 30% of them .
tethered cord may present with subtle changes in prior neurophysical situation , which become progressive and disabling if neglected .
spinal cord tethering due to dermoid cyst subsequent to mmc surgery has been reported so far , which can occur decades after closure.[58 ] all patients with symptomatic tethered cord have attachment of spinal cord to the prior closure site , which can be associated with inclusion tumors in 16% of instances .
dermoid tumors following mmc surgery may result from inadequate excision of dermal elements during dissection of placode or dura mater from the skin or with implantation of dermal elements inside the repair site .
, this tumor can be an associated abnormality with mmc , which was undiagnosed or neglected because of very small size at the time of primary repair , especially during surgery without magnification .
cases of dermoid tumor in mmc children who were operated during the intrauterine period have been reported , suggesting a higher potential for rapid growth of this tumor in lesions that were closed in utero rather than after birth .
dermal sinus tract as a rare congenital abnormality is accompanied by inclusion tumors in 43% of instances , wherein most tumors are dermoids .
intramedullary spinal abscess without sinus tract is extremely rare , but a devastating condition in children.[1216 ] intramedullary abscess and dermoid tumor without dermal sinus have been reported before ; however , not following mmc repair and especially not associated with tethered cord . in order to explain infected dermoid tumor in this patient with prior mmc repair , we propose several explanations
implantation of bacteria during closure of mmc sac can lead to abscess formation but occurence three years after the first surgery seems to be unusual .
microscopic sinus tract through the preceding mmc surgery incision can be a way for bacteria to reach the subcutaneous space .
hematogenous superinfection of the dermoid cyst during repeated urinary tract infections in mmc patient is another possiblity for abscess formation in this case .
dermoid tumors , even infrequent , should be considered in the differential diagnosis of the causes of neurological deterioration in patients with a history of mmc repair . along with tethered cord syndrome
, dermoid tumor can complicate the prior neurological and physical status of the child , and should be searched vigilantly during evaluation of these patients . because of rapid growth of dermoid tumors and associated infection , these can deteriorate the previous neurological status in a more aggressive and destructive manner as compared to tethered cord per se .
awareness of such pathology in patients with previous history of myelomeningocele repair , early diagnosis and surgical intervention can provide better result with less disability .
tethered cord syndrome should be investigated in any patient with a history of mmc repair if one finds neurological , orthopedics , or urological deterioration .
dermoid tumor is considered as an important differential diagnosis during thorough evaluation of the causes of worsening . in order to minimize the risk of dermoid tumor development following mmc surgery , any residual epidermal or dermal elements
the operative field should be explored accurately proximal and distal to the sac to find any associated anomaly or minute inclusion tumor and prevent late inclusion tumor formation and tethered cord .

Answer:
intramedulary dermoid tumors are rare tumors mostly found associated with dermal sinus tracts .
 spinal dermoid tumor can occur after myelomeningocele repair .
 infected dermoid tumors are reported in patients with dermal sinus tracts as well , but have never been reported subsequent to myelomeningocele surgery . here ,
 we report a rare association of infected dermoid tumor with tethered cord without dermal sinus tract in a child who had been operated for myelomeningocele during infancy .


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:
nearest neighbor approaches were developed to predict the folding stabilities of nucleic acid secondary structures ( 1 ) .
these parameter sets utilize empirical rules , generally derived from optical melting experimental data , as the basis of the predictions . for rna , rules exist for predicting both free energy and enthalpy change of watson  crick helices , gu pairs and loops ( 25 ) . parameters for dna have also been assembled for predicting watson
crick pair free energy and enthalpy change and free energy changes of loops ( 6,7 ) .
these parameter sets are the basis of computer programs that predict low free energy secondary structures .
such programs include mfold / unafold ( 8,9 ) , the vienna rna package ( 10 ) , rna structure ( 2 ) , rnasoft ( 11 ) and sfold ( 12 ) .
additional approaches that use statistical learning of parameters for rna folding have also used the rules from the nearest neighbor methods and derived new parameter values ( 13,14 ) .
nearest neighbor parameter sets include both a set of rules , called either equations or features , for predicting stability and a set of parameter values used by the equations ( 14 ) . for rna ,
separate rules exist for predicting stabilities of helices , hairpin loops , small internal loops , large internal loops , bulge loops , multibranch loops , exterior loops and pseudoknots .
given the number of rules and constraints on the length of journal publications , it is difficult to assemble all the parameters in one publication and provide meaningful tutorials for using the parameters .
this is a barrier to software development for novel algorithms that could take advantage of the parameters .
for example , many software packages that use rna parameters still implement the set of parameters assembled in 1999 ( 4 ) , in spite of the fact the rna parameters were updated in 2004 ( 2 ) based on experimental results .
the nearest neighbor database ( nndb ) is a web - based tool for assembling and archiving complete nearest neighbor sets , including rules and values .
currently , the 1999 and 2004 sets of rna folding parameters are provided ( 25 ) .
the nndb is built using a set of static html , specifically xhtml 1.0 transitional pages with a page hierarchy shown in figure 1 .
text is encoded in unicode ( utf-8 ) to facilitate display of equations in pages with diverse browsers running on diverse operating systems .
the top - level page provides access to a help page , available parameter sets and a page of references to rna optical melting experiments .
additionally , links provide downloading of the whole database in either zip or gzipped tar format .
the help page introduces the purpose of the database and defines basic terms , including the set of structural features defined by secondary structures .
for example , figure 2 , from the help page , shows an rna secondary structure that illustrates the loop features covered by nearest neighbor parameter sets .
the basic equations for utilizing the parameters to extrapolate folding free energy changes to temperatures other than 37c and to predict melting temperatures are also provided .

this figure illustrates the page hierarchy by following the linked pages down through the 1999 parameters and down to the hairpin loop pages .
note that there are five example calculations for hairpin loops to illustrate the separate sequence - dependent rules that are used depending on the specific loop .

figure 2.an rna secondary structure illustrating the types of features included in nearest neighbor parameter sets .
internal loops have nucleotides not in canonical pairs on each of two strands , but bulge loops have nucleotides not in canonical pairs on only one strand .
formally , a pseudoknot occurs when there are at least two pairs , with indices i paired to j and i paired to j , that satisfy the condition i < i < j < j. the pseudoknot helix is often considered to be composed of the fewest pairs that need to be removed to relieve the pseudoknot ( 19 ) . in this structure ,
this figure illustrates the page hierarchy by following the linked pages down through the 1999 parameters and down to the hairpin loop pages .
note that there are five example calculations for hairpin loops to illustrate the separate sequence - dependent rules that are used depending on the specific loop .
an rna secondary structure illustrating the types of features included in nearest neighbor parameter sets .
internal loops have nucleotides not in canonical pairs on each of two strands , but bulge loops have nucleotides not in canonical pairs on only one strand .
formally , a pseudoknot occurs when there are at least two pairs , with indices i paired to j and i paired to j , that satisfy the condition i < i < j < j. the pseudoknot helix is often considered to be composed of the fewest pairs that need to be removed to relieve the pseudoknot ( 19 ) . in this structure ,
the tan nucleotides are in pairs that could be removed to relieve the pseudoknot . for each set of parameters ,
for example , the 1999 rna rules predict only folding free energy changes ( 4 ) , but the 2004 rules can be used to predict both folding free energy and enthalpy changes ( 2,5 ) . for each structural feature
, a page defines the basic equations and provides links to parameter values ( in plain text and html ) , references and tutorial pages ( e.g. figure 3 ) .
the number of tutorials varies from feature to feature ; the set of tutorials is designed to cover each type of rule that can be encountered in practice .
 crick helix parameters are covered with two tutorials , one for self - complementary and one for non - self - complementary strands .
these two tutorials also demonstrate the difference in the calculation when there are terminal au base pairs , which receive a free energy and enthalpy change penalty ( 3 ) , because the self - complementary duplex example has two terminal au pairs and the non - self - complementary case has no terminal au pairs .

this tutorial demonstrates the prediction of folding free energy change for a hairpin loop of six unpaired nucleotides using the 2004 parameters ( 2,3 ) . an example tutorial from the database .
this tutorial demonstrates the prediction of folding free energy change for a hairpin loop of six unpaired nucleotides using the 2004 parameters ( 2,3 ) .
individual pages above the level of value tables have top banner , a left navigation bar that allows the user to navigate back up the hierarchy to any level above and a bottom bar with the date of last editing . for pages edited after the database has gone online , previous versions of the page are available using this bottom content bar . to facilitate indexing by search engines ,
all pages have a descriptive title , including the set of parameters to which it belongs ( if applicable ) .
the first release of the nndb contains the rna folding rules assembled in 1999 and 2004 ( 25 ) .
these rules represent the most recent set of parameters and a prior set that is widely used in software packages . because folding rules are derived to work as a set , the two versions of rules and values should not be mixed and the website hierarchy reinforces this .
it is anticipated , for example , that additional pages will be written to include nearest neighbors for dna folding ( 6,7 ) and for predicting rna pseudoknot stabilities ( 1518 ) .
additionally , the values derived from the re - estimation of the values of the 1999 parameter set using the set of known rna secondary structures will also be included ( 14 ) .
the nndb is designed to provide a convenient location for assembling parameter sets for predicting the stability of nucleic acid secondary structures .
it is modular in design , which facilitates its future expansion to contain additional parameter sets .
furthermore , the web format makes it feasible to provide extensive tutorials for utilizing the parameters , which is generally not possible in print .
the creation of the nndb was supported by united states national institutes of health grants gm076485 to d.h.m . and gm22939 to d.h.t . funding for open access charge : united states national institutes of health .

Answer:
the nearest neighbor database ( nndb , http://rna.urmc.rochester.edu/nndb ) is a web - based resource for disseminating parameter sets for predicting nucleic acid secondary structure stabilities . for each set of parameters ,
 the database includes the set of rules with descriptive text , sequence - dependent parameters in plain text and html , literature references to experiments and usage tutorials .
 the initial release covers parameters for predicting rna folding free energy and enthalpy changes .


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:
radiological investigations and therapeutics have become an integral part of the management of critically ill patients in the intensive care unit ( icu ) .
patients admitted to the icu routinely undergo bedside imaging procedures such as chest radiographs for diagnosing heart , lung and other pathology , and for confirmation of the position of devices like endotracheal tubes , nasogastric tubes , central venous catheters and intercostal drains .
a review article has suggested that among icu patients , up to 65% of daily chest radiographs and 70 - 75% of chest computerized tomography ( ct ) scans reveal significant or unsuspected abnormalities that may lead to a change in the patient 's management .
further , critically ill patients are frequently transported to the ct scan as well as digital subtraction angiography suites for diagnostic and therapeutic procedures such as angiography , embolization and stenting . in most situations ,
the icu team is responsible for the transport and management of the patient in the radiology department for these procedures .
there is , therefore , potential radiation exposure to healthcare workers , particularly for those working for long periods of time in the icu .
epidemiological data indicates that the exposure to even low - dose radiation may be a cause for concern because such exposure can result in leukemia , thyroid malignancies and other cancers .
nonneoplastic effects of radiation include genetic mutation and developmental malformation in children whose mothers were exposed to radiation during pregnancy .
a number of studies have looked at radiation exposure in critically ill patients undergoing repeated radiological procedures .
one study has specifically focused on the pediatric age group probably in view of the high ratio of exposure to patient size and the potential for long - term sequelae as the radiation effects have a longer period to become manifest . however , the available literature on the extent of radiation exposure to icu personnel is scarce and relates mainly to the level of scattered radiation within the icu .
the conclusion of these studies is that the level of radiation exposure is extremely low and does not pose a hazard to icu personnel .
none of these studies have considered the additional radiation exposure to icu personnel involved in the management of critically ill patients in the radiology department . in our icu in a tertiary care cancer referral center , resident doctors working on 12 h shifts in the icu are also responsible for the transport and management of icu patients when they undergo diagnostic and therapeutic procedures in the radiology department .
we , therefore , carried out this study to determine the total radiation exposure to icu resident doctors involved in the course of their duties .
we conducted a prospective , observational study in the icu and postanesthesia care unit ( pacu ) of a 500-bedded tertiary care cancer referral center in mumbai , india from september 2012 to february 2013 .
all resident doctors who gave voluntary written consent to participate in the study were included .
since the study did not involve patient contact , the requirement for obtaining consent from patients was waived by the ethics committee .
the study was carried out in accordance with the principles of good clinical research practice .
the resident doctors provide 24 h cover , working in 12 h shifts , with four doctors in each shift . in each shift
the icu has a total of 14 beds as shown in figure 1 . on another floor
is the pacu with 23 beds , subdivided into 14 postoperative recovery room beds and 9 intensive care beds [ figure 2 ] .
residents provide care for patients in the icu and pacu and also accompany patients from these locations for radiological procedures in the ct scan or interventional radiology suites .
location of thermoluminescent dosimeters are shown with filled triangles layout of postanesthesia care unit showing location of thermoluminescent dosimeter in pacu ( tld surrounded by beds ) and other in long lobby as control tld to detect levels of radiation , we used thermoluminescent dosimeters ( tlds ) which are a type of radiation detector .
the tld measures cumulative dose of ionizing radiation exposure by measuring the amount of visible light emitted from a crystal in the detector when the crystal is heated .
tlds can measure a wide dosimetric range ( from 10 gray to 10 grays ) of radiation exposure and are routinely used as personal dosimeters because they are small in size , convenient to use and not expensive .
a tld was given to each of the four resident doctors ; they were handed over to the next team during shift changeover .
in addition , three tlds were kept in nursing stations in icu , and one tld was placed in the pacu .
one tld was kept in the doctors ' duty room which was within the premises of the icu , and the last was kept as a control in the office of the department of anesthesia , critical care and pain , remote from icu and pacu , and where no radiological procedures were performed .
the layout of icu and pacu is represented by figures 1 and 2 respectively and locations of tlds are marked with filled triangles .
the participating resident doctors were instructed to wear the tlds at all times during their duty hours .
staff not required to be present during radiographic procedures were kept at least 3 m away from the patient ( a distance at which exposure from scattered radiation is considered negligible ) .
it was ensured that patients who were shifted from icu to the radiology suite were accompanied by one icu resident and that the resident was wearing his tld throughout .
residents , if required to be directly involved in the radiologic procedure in suites , wore lead aprons , and the tld was underneath the lead apron . bedside chest
x - rays in the icu were done by siemens multimobil 2.5 ( manufactured by siemens ltd , goa , india ) , ct and ct guided biopsies were performed on siemens somatom emotion 16 ( manufactured by siemens shanghai medical equipments ltd , shanghai china ) and ge light speed 16 ( manufactured by general electric co. , milwaukee , usa ) respectively .
interventional radiology procedures were carried out using ge innova 4100 iq ( manufactured by ge medical systems , france ) .
the study was carried out in two phases of 3 months each . at the end of the first phase ,
the tlds were handed over to department of nuclear medicine for analysis and another set of tlds was issued at the same time . during the period of the study , we maintained a database of procedures performed both in the icu and in the radiological suites along with the bed number and the patient 's hospital registration number .
the primary outcome of this study was to quantify the cumulative radiation exposure to the resident doctors working in the icu over a period of 6 months in the course of their duties .
the secondary outcomes were to measure the cumulative scattered radiation exposure in various areas of the icu calculated as the average of readings of icu tld badges over 6 months and the estimated cumulative radiation exposure to the resident doctors per year .
the control tld placed in the department of anesthesia served as a measure of baseline atmospheric ionizing radiation , and all other values are reported above this baseline .
the results of dosimetric analysis of residents tlds during the two phases are shown in table 2 .
readings from tlds placed in the nursing station and doctors ' duty room during both phases were immeasurable .
the mean values in the first and last 3 months were 0.052 and 0.069 msv respectively , though the highest individual value approached 0.1 msv .
since this was recorded in a 3 month period , the projected reading for similar exposure throughout the year , even assuming a 24 h duty period , would be 0.4 msv , which is well below the safety limit of 20 msv / year .
revolutionary progress in the field of medical imaging has given a big leap to advances in medical diagnostics and therapeutics .
this development has also infiltrated the field of critical care medicine , and radio - diagnosis and interventional radiological procedures now play a key role in the management of critically ill patients . while this advancement offers the advantages of rapid bedside diagnosis , and cost - effective and minimally invasive treatment options to critically ill patients , it carries the danger of exposure of patient and physician to radiation .
the detrimental effects of exposure to even low - level ionizing radiation have always been known ; however , there is renewed concern because of its wide - spread use in medical radio - diagnosis and therapeutics in critically ill patients .
it is , therefore , natural that there may be concerns about the long - term effects of radiation exposure to doctors working for long periods of time in the icu .
in addition , where icu doctors are responsible for transport of patients to the radiology suite , the extent of radiation exposure is increased .
it is reassuring that the results of our study confirm that the extent of radiation exposure to critical care physician during the course of his duty is well within acceptable limits .
there is considerable literature on occupational hazards of radiation exposure among radiologists ; however , it is difficult to directly extrapolate the conclusions of these studies to the icu .
working conditions in the icu do not mimic those in radiology suites - working hours tend to be long , there is a need to accompany mechanically ventilated and hemodynamically unstable patients inside the radiology suite for procedures , and icu doctors may sometimes take radiation safety norms lightly .
a study performed in a trauma icu ( ticu ) has concluded that radiation exposure is not a significant occupational hazard for the ticu personnel .
similarly , another study looked into the radiation exposure to icu nurses and found that the exposure was well below the permissible level .
the strength of our study is that it was planned in a more pragmatic way - apart from bedside radiological procedures , we also took into account the radiation exposure to icu residents accompanying the patient to radiological suites for diagnostic and therapeutic procedures
. ionizing radiation from fluoroscopy in the ct scan or interventional radiology suites may be significant and were not considered in the previous studies .
we also tried to measure the amount of scattered radiation within the icu and the pacu , which contributes to overall radiation exposure .
even after taking these additional sources of radiation exposure into account , we found that the cumulative radiation exposure was negligible .
the number and types of bedside and out - of - icu radiological procedures can vary on a day - to - day basis according to the case - mix of the icu population , and this may affect the overall radiation exposure ; however , this study was carried out over a period of 6 months , and the data obtained would have been adequately representative .
the other limitation relates to the generalizability of the study ; differences in the types of cases , working pattern of resident doctors , quality and maintenance of radiological equipment between hospitals may restrict the applicability of these results to other hospitals .
however , given the large margin of safety that our study has shown , it is unlikely that exposure levels would be dangerously high in any other setting .
though , with advances in technology , the number and types of radiological procedures performed on patients are likely to increase . furthermore , there is a growing trend toward using radionuclide - based positron emission tomography scans for diagnostic procedures in critically ill patients especially when they are admitted to icu during their diagnostic work - up .
some of these patients may continue to emit radiation long after their procedures are completed .
though none of these patients featured in our study , it will add to the radiation exposure to doctors .
the results of this study do not in any way underrate the need to follow safety precautions , while carrying out radiological procedures in critically ill patients .
the levels of exposure found in this study should be interpreted bearing in mind that standard protection norms were used by all personnel involved in the study . with these precautions in place ,
radiation exposure to doctors managing critically ill patients in the icu is minimal and acceptable .
literature on radiation exposure among icu doctors is scarce . in addition to bedside radiological procedures , the risk of exposure may be increased if the same doctors accompany icu patients for out - of - icu radiological investigations .
however , we found that if standard safety precautions were followed , cumulative radiation exposure to icu resident doctor was well within permissible limits and was not the cause of concern and hence routine personal dosimetric monitoring is not needed for residents in icu .
however , in view of changing practice , there is a need to repeat such audits periodically to monitor radiation exposure .

Answer:
background and aims : with the expanding use of diagnostic and therapeutic radiological modalities in critically ill patients , doctors working in intensive care units ( icus ) are increasingly exposed to ionizing radiation .
 this risk of radiation exposure occurs not only during bedside radiologic procedures , but also when icu physicians accompany patients to radiology suites .
 the aim of this study was to quantify levels of radiation exposure among medical professionals working in the icu.materials and methods : the study was carried out prospectively over 6 months in the icu of a tertiary - referral cancer hospital .
 two teams consisting of 4 icu resident doctors each were instructed to wear thermoluminescent dosimeters ( tlds ) during their duty shifts .
 standard radiation protection precautions were used throughout the study period .
 tlds were also placed in selected areas of the icu to measure the amount of scattered radiation .
 tlds were analyzed at the end of every 3 months.results:the readings recorded on tlds placed in the icu were almost immeasurable .
 the mean value of residents ' radiation exposure was 0.059 msv , though the highest individual reading approached 0.1 msv .
 the projected maximum yearly radiation exposure was 0.4 msv.conclusions:if standard radiation safety precautions are followed , the cumulative radiation exposure to icu resident doctors is well within permissible limits and is not a cause of concern .
 however , with the increasing use of radiological procedures in the management of critically ill patients , there is a need to repeat such audits periodically to monitor radiation exposure .