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Biomedical subjects

H Khan

Publications and source records attributed to H Khan.

At least 55 records · Page 3Linked to original sources
PubMed1996

Screening for cytomegalovirus retinitis in children.

OBJECTIVES: To identify immunosuppressed children who are at risk of cytomegalovirus (CMV) retinitis developing and to evaluate the use of laboratory results for identifying this risk. DESIGN: Prospective cohort and retrospective case-control series. SETTING: University hospital pediatric referral center. PATIENTS: Fifty-six consecutive immunocompromised children (ie, the prospective group) with laboratory evidence consistent with acute or recently acquired CMV infection, which was defined as CMV cultured from the blood, urine, nasopharynx, or biopsy specimen, recent seroconversion, a 4-fold increase in the CMV antibody titer, or an antibody titer of 1:512 or greater. Ninety-three immunocompromised children (ie, the retrospective group) with acute CMV or previous CMV exposure, which was defined as a CMV titer of 1:4 or greater and less than 1:512. MAIN OUTCOME MEASURE: Occurrence of CMV retinitis. RESULTS: Cytomegalovirus retinitis developed in 3 children in the prospective group and in 4 children in the retrospective group. The causes of immunosuppression were severe combined immunodeficiency syndrome (n = 2), severe combined immunodeficiency syndrome status post bone marrow transplantation (n = 1), acquired immunodeficiency syndrome (n = 1), and acquired immunodeficiency syndrome status post bone marrow transplantation for leukemia (n = 1), renal transplantation (n = 1), and chemotherapy for leukemia (n = 1). Cytomegalovirus retinitis was associated with a positive CMV culture result from the urine (P = .03) or nasopharynx (P < .001) in the retrospective group. In the retrospective group, one child with congenital CMV infection and CMV retinitis was excluded from analysis because laboratory tests for CMV were not obtained prior to ganciclovir therapy. CONCLUSIONS: Cytomegalovirus retinitis is uncommon in children compared with adults; it occurred in 5% of the children in our series. A screening ophthalmologic examination should be considered in immunocompromised children with positive CMV laboratory results, particularly positive results of urine or nasopharynx cultures.

Adolescent↗
PubMed1996

Fulminant hepatic failure in pregnant women: acute fatty liver or acute viral hepatitis?

BACKGROUND: Hepatitis E virus, which is endemic in our region, can cause severe liver dysfunction in pregnant women and this can be clinically confused with acute fatty liver of pregnancy. METHODS: We studied the clinical and laboratory data as well as the maternal and fetal outcomes of 12 pregnant women presenting with fulminant hepatic failure in order to determine the etiology of the disease. The clinical diagnoses were subsequently correlated with serologic assays for acute HEV infection. All patients were severely ill with deep jaundice, grade 3-4 encephalopathy and abnormal prothrombin times. RESULTS: A clinical diagnosis of acute viral hepatitis was made in nine patients and of acute fatty liver in the other three cases. IgM and IgG antibodies confirmed acute viral hepatitis E in six of the nine patients while one had acute hepatitis A infection. HEV IgM and IgG antibodies were, however, also positive in two of the three patients thought to have acute fatty liver. Maternal and fetal mortality were 16.6% and 50%, respectively. CONCLUSIONS: We conclude that hepatitis E is the usual cause of acute liver failure in our pregnant women and that clinical and laboratory features do not permit accurate distinction between acute HEV infection and acute fatty liver of pregnancy. The prognosis in patients with acute HEV infection is much better than in other groups with severe liver failure (mortality 16% vs 68%).

Acute Disease↗
PubMed1996

Community acquired and post-transfusion hepatitis C "is there a difference?".

We analyzed 77 consecutive hepatitis C antibody positive patients to compare the history, laboratory data and histological features of community acquired (CA) and post-transfusion (PT) hepatitis C. Forty-six patients had "CA" and 31 "PT" hepatitis C. Mean age in both groups was same (45.67 vs 46 years). Male to female ratio was 2:1 in the CA group and 1:2.4 in the PT group. Mean duration between jaundice and first presentation was 8.9 years in the CA group and the mean duration between transfusion and first presentation was 9.8 years in PT group. No significant difference was found between two groups in the laboratory data. Liver biopsy was done in 32 patients (19 CA and 13 PT group). Mean histological score for disease activity was 9.3 in both groups, although more (68%) patients in the CA group had cirrhosis with chronic active hepatitis, (CAH) as compared to the PT (54%) group. Hepatitis C is an important cause of CA hepatitis. PT hepatitis C is more common in females because of increased likelihood of receiving transfusion for obstetric and gynaecological reasons. There is no significant difference in the laboratory and histological features between CA and PT hepatitis C.

Adult↗
PubMed1995

Enhancement of computed tomography liver contrast using iomeprol-containing liposomes and detection of small liver tumors in rats.

RATIONALE AND OBJECTIVES: We evaluated iomeprol-containing liposomes (Lipiom), a new contrast medium for computed tomography (CT) liver scanning, in an animal model of chemically induced hepatocellular carcinomas and other liver tumors in rats. METHODS: Liver tumors were induced by administration of carcinogens to rats, either 0.55% (w/w) 1'-hydroxysafrole in the diet or induction by 3'-methyl-4-diethylaminoazobenzene followed by promotion with carbon tetrachloride. CT scanning was performed 1-3 hr after intravenous injection of iomeprol-containing liposomes. RESULTS: After injection of iomeprol-containing liposomes at a dose of 70 mg of liposome-entrapped iodine per kilogram of body weight, the normal liver parenchyma showed a contrast enhancement, in Hounsfield units, of more than 60% over the control value before bolus. Liver tumors with no or few Kupffer cells were not enhanced and appeared as dark areas within the normal parenchyma. Tumors and pretumoral lesions devoid of Kupffer cells, as small as 3 mm in diameter, could be distinguished using this non-invasive method. CONCLUSION: CT liver scanning after injection of iomeprol-containing liposomes appears to be promising method for detecting liver tumors and focal liver lesions.

Animals↗
PubMed1995

Cholera admissions in adults 1989-1994: a hospital based study.

In order to gain insight into the distribution of cholera over the years and proportion of monthly admissions under our adult medical services, we scrutinized our records of hospital discharges between 1989 and 1994. Only culture positive cases were included. Each year most of the cases of cholera are admitted between May and November with almost disease free interval from December to April. In 1992 admission rate was 4.24/1000 medical admissions which increased to 12.65 in 1993 and 13.73 in 1994. Though the Vibrio cholerae 01 Ogawa was the major isolate upto May, 1993, Vibrio cholerae non-01 serogroup 0139 dominated between June and August, 1993. Ogawa strain re-established itself in October, 1993. In August, 1994, non-01 strain reappeared and became the major isolate in September. Cholera has caused multiple epidemics throughout the Indian subcontinent. Since 1800, there have been seven pandemics of cholera. The seventh pandemic originated in Indonesia and continues today.

Adolescent↗
PubMed1993

Cloning of alternately spliced mRNA transcripts coding for variants of ovine testicular follitropin receptor lacking the G protein coupling domains.

We report the cloning and characterization of two alternately spliced forms of ovine testicular follitropin receptor mRNA. A smaller receptor cDNA (151 A1) of 727 bp codes for a possible soluble receptor protein of 134 amino acids arising from exons 1-4 of the full length receptor. The 1.1 Kb cDNA clone (HK 18) extending up to the 8th exon codes for a mature protein of 259 amino acids with a single membrane spanning domain predicted by hydropathy analysis. As these structures account for 34% and 61% respectively of the extracellular domain of the full length receptor, we suggest that their putative protein products are likely to possess moderate or high affinity binding sites of physiological significance.

Alternative Splicing↗
PubMed1993

Molecular cloning and expression of the ovine testicular follicle stimulating hormone receptor.

A sheep testicular cDNA library constructed in pcDNA1 vector was screened with a probe generated by polymerase chain reaction (PCR) and corresponding to a 1.6 kb fragment of the rat luteinizing hormone receptor cDNA. Several clones hybridizing to the rat probe at low stringency were sequenced to obtain 95% of the putative full-length ovine follicle-stimulating hormone receptor (oFSH-R) cDNA. The missing 5' region was obtained by PCR amplification of the cDNA library. Sequencing revealed a 2085 nucleotide open reading frame encoding a mature protein of 678 amino acids (74,580 daltons). The oFSH-R is remarkably similar (> 90%) to the human and rat FSH receptors, has a structural motif like the G protein-coupled family of receptors and contains 3 potential sites for N-linked glycosylation. RNA blot analysis revealed two major transcripts of 2.6 kb and 6.7 kb in size and a smaller transcript of about 1 kb in the sheep testis. A 53 residue segment in the extracellular domain unique to the receptor contains more than 50% of residues bearing functional side chains that could participate in ligand (FSH) interaction and/or signal transduction. Transfection of human fetal kidney cell line (293) with the cloned oFSH receptor cDNA based in pcDNA1/Neo vector revealed functional expression. Labeled oFSH bound to receptor expressed on the membrane with high affinity and specificity. In stably transfected 293 cells, purified oFSH and hFSH but not oLH stimulated cyclic AMP accumulation. Chemically deglycosylated oFSH (DG-oFSH) was inactive in these cells but it effectively blocked the action of native hormone.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

The patterns and treatment of recurrence following radiotherapy for carcinoma of the oral cavity.

In many centres carcinoma of the oral cavity, if relatively early, is treated by irradiation. The present study includes 186 patients treated in this manner. The primary recurrence rate for previously untreated patients was 34% and was not significantly affected by host or tumour factors. The 5-year survival for the 144 previously untreated patients was 65%, and salvage surgery offered a 35% chance of cure. Survival was reduced in patients aged 60 years and over (P < 0.02). The recurrence rate in cervical lymph nodes following radiotherapy was 38% and was more likely to occur for primary sites in the tongue and floor of mouth (P < 0.01). The five-year survival rate after nodal recurrences was 31% and was predicted only by the presence of extracapsular rupture (P < 0.01). One-third of patients had died of causes other than the primary tumour at 5 years and one-third had died of the original tumour. The rest of the patients are alive and well, only 7% having had a major resection. We feel that the present policy has optimum cure rate whilst saving most patients from major surgery.

Female↗
PubMed1993

Identification of reentry circuit sites during catheter mapping and radiofrequency ablation of ventricular tachycardia late after myocardial infarction.

BACKGROUND: Ventricular tachycardia reentry circuits in chronic infarct scars can contain slow conduction zones, which are difficult to distinguish from bystander areas adjacent to the circuit during catheter mapping. This study developed criteria for identifying reentry circuit sites using computer simulations. These criteria then were tested during catheter mapping in humans to predict sites at which radiofrequency current application terminated ventricular tachycardia. METHODS AND RESULTS: In computer simulations, effects of single stimuli and stimulus trains at sites in and adjacent to reentry circuits were analyzed. Entrainment with concealed fusion, defined as ventricular tachycardia entrainment with no change in QRS morphology, could occur during stimulation in reentry circuit common pathways and adjacent bystander sites. Pacing at reentry circuit common pathway sites, the stimulus to QRS (S-QRS) interval equals the electrogram to QRS interval (EG-QRS) during tachycardia. The postpacing interval from the last stimulus to the following electrogram equals the tachycardia cycle length. Pacing at bystander sites the S-QRS exceeds the EG-QRS interval when the conduction time from the bystander site to the circuit is short but may be less than or equal to the EG-QRS interval when the conduction time to the circuit is long. The postpacing interval, however, always exceeds the tachycardia cycle length. When conduction in the circuit slows during pacing, the S-QRS and postpacing intervals increase and the slowest stimulus train most closely reflects conduction times during tachycardia. Endocardial catheter mapping and radiofrequency ablation were performed during 31 monomorphic ventricular tachycardias in 15 patients with drug refractory ventricular tachycardia late after myocardial infarction. During ventricular tachycardia, trains of electrical stimuli or scanning single stimuli were evaluated before application of radiofrequency current at the same site. Radiofrequency current terminated ventricular tachycardia at 24 of 241 sites (10%) in 12 of 15 patients (80%). Ventricular tachycardia termination occurred more frequently at sites with entrainment with concealed fusion (odds ratio, 3.4; 95% confidence interval [CI], 1.4 to 8.3), a postpacing interval approximating the ventricular tachycardia cycle length (odds ratio, 4.6; 95% CI, 1.6 to 12.9) and an S-QRS interval during entrainment of more than 60 milliseconds and less than 70% of the ventricular tachycardia cycle length (odds ratio, 4.9; 95% CI, 1.4 to 17.1). Ventricular tachycardia termination was also predicted by the presence of isolated diastolic potentials or continuous electrical activity (odds ratio, 5.2; 95% CI, 1.8 to 15.5), but these electrograms were infrequent (8% of all sites). Combinations of entrainment with concealed fusion, postpacing interval, S-QRS intervals, and isolated diastolic potentials or continuous electrical activity predicted a more than 35% incidence of ventricular tachycardia termination during radiofrequency current application versus a 4% incidence when none suggested that the site was in the reentry circuit. Analysis of the postpacing interval and S-QRS interval suggested that 25% of the sites with entrainment with concealed fusion were in bystander areas not within the reentry circuit. At restudy 5 to 7 days later, 6 patients had no monomorphic ventricular tachycardia inducible, and inducible ventricular tachycardias were modified in 4 patients. None of these 10 patients have suffered arrhythmia recurrences during a follow-up of 316 +/- 199 days, although 4 continue to receive previously ineffective medications. CONCLUSIONS: Regions giving rise to reentry after myocardial infarction are complex and can include bystander areas, slow conduction zones, and isthmuses for impulse propagation at which radiofrequency current lesions can interrupt reentry.

Aged↗
PubMed1993

Microscopic colitis: a diagnosis to consider.

Microscopic colitis is a syndrome of chronic watery diarrhoea for which no cause can be identified other than the presence of diffuse, chronic inflammation in the lamina propria on colonic biopsy. Endoscopically and radiologically the colon appears normal. We studied case records of 215 patients presenting to our institution over a three year period with chronic diarrhoea. Nineteen patients were included in the study where two pathologists agreed on the presence of chronic inflammation on colonic biopsies. All patients had watery diarrhoea with urgency. Stool examination, laboratory indices, radiology of the large and small bowel and colonoscopy were normal in all patients. Patients did not respond to a variety of drugs. A significant improvement was noted in one patient given salazopyrin. In developing countries chronic diarrhoea is most often attributed to infection and treated with antibiotics. Microscopic colitis should be considered in the diagnosis of such patients.

Adult↗
PubMed1993

Outcome of biliary tract surgery in unknown cirrhotics: a case-control study.

The substantial risk of biliary surgery in patients with liver cirrhosis may be reduced by preoperative preparation but the problem of the unknown cirrhotic remains. We studied 18 patients found incidentally to have cirrhosis at surgery. The perioperative complications and the outcome in these patients was compared with 18 non-cirrhotic patients, computer matched for age and sex, undergoing the same operations. Mean blood loss at operation was 324 ml (SD 218.1 ml) in the cirrhotic group and 105 ml (SD 74.7 ml) in the control group (P < 0.01). The postoperative complication rate was 38% in cirrhotics, but zero in controls (P < 0.01). The length of hospital stay was significantly increased in the cirrhotic group (P < 0.01). There was no mortality in either group. The incidental finding of cirrhosis at biliary surgery is associated with increased peroperative bleeding and increased morbidity. There is no increase in mortality in such patients.

Cholecystectomy↗
PubMed1992

Interleukin-1 beta stimulates decidual stromal cell cyclo-oxygenase enzyme and prostaglandin production.

The cytokine interleukin-1 (IL-1 beta) increased prostaglandin production by decidual stromal cells in culture in a time and dose dependent manner. Optimum conditions for stimulation were found to be for 24 hours at a concentration of 100 pg IL-1 beta/ml. An apparent increase in cyclo-oxygenase enzyme synthesis accompanied the increase in prostaglandin production, and both changes were inhibited by the protein synthesis inhibitor cycloheximide. This implicates protein synthesis in the stimulatory effects of IL-1 beta, which may be mediated through the increase in cyclo-oxygenase enzyme. A pre-incubation period of 72 hours was found to be necessary to observe the stimulatory effect of IL-1 beta on prostaglandin production, but this did not seem to be due to any change in the sensitivity of the cells to IL-1 beta; the increase in the number of cyclo-oxygenase positive cells was the same if IL-1 beta was added on day 1, day 2 or day 3 of culture, even though prostaglandin production was not stimulated on day 1 or day 2. Cycloheximide increased prostaglandin production on the first two days of culture and had no effect on the third day of culture. This was interpreted as indicating that a factor inhibiting cyclo-oxygenase activity was synthesised during the initial period of culture, which prevented any increase in prostaglandin production following the increase in enzyme synthesis.

Cycloheximide↗
PubMed1992

Effects of platelet-activating factor on prostaglandin E2 production by intact fetal membranes.

OBJECTIVE: The hypothesis tested in this study is that platelet-activating factor increases prostaglandin E2 synthesis from fetal membranes. STUDY DESIGN: Fetal membrane disks obtained before or after labor were incubated with or without platelet-activating factor for time periods of up to 24 hours. The production of prostaglandin E2 and its inactive metabolites was determined by specific radioimmunoassays. RESULTS: Platelet-activating factor (1 to 10 mumol/L) stimulated the production of prostaglandin E2 and its metabolites by intact fetal membranes and chorion-decidua threefold to fourfold after 24 hours of incubation. Platelet-activating factor had far greater effects on the production of prostaglandin E2 by intact fetal membranes obtained after the onset of labor, such that prostaglandin E2 production was increased by tenfold to 100-fold. CONCLUSION: These results suggest that platelet-activating factor mainly stimulates prostaglandin E2 production by the chorion-decidua before labor and that it may act in synergism with other stimulatory factors present in the fetal membranes during labor.

Amnion↗
PubMed1992

Changes in decidual stromal cell function associated with labour.

OBJECTIVE: To determine whether decidual cells produce altered levels of prostaglandins after labour. DESIGN: Decidual stromal cells and macrophages were isolated before and after labour, and the production of prostaglandins E2 and F2 alpha measured. Changes in the numbers of cyclooxygenase enzyme positive cells were assessed by immunocytochemistry. RESULTS: Decidual stromal cells obtained after labour produced 30 times more prostaglandins E2 and F2 alpha in culture than cells obtained before labour. The increased production persisted for up to 72 h of culture, and was associated with an increase in the numbers of cyclooxygenase-positive cells from less than 5% to greater than 95%. No changes in macrophage function were observed. CONCLUSION: Increased levels of prostaglandins E2 and F2 alpha were released from decidual stromal cells after labour, suggesting that these cells may be an important source of prostaglandins in labour.

Decidua↗