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Biomedical subjects

S Hamid

Publications and source records attributed to S Hamid.

At least 37 records · Page 2Linked to original sources
PubMed1997

Nicotine induces long-lasting potentiation in the dentate gyrus of nicotine-primed rats.

A challenge dose of nicotine (0.4 mg kg-1 s.c.) produced a long-lasting potentiation (LLP) of field EPSPs evoked in the dentate gyrus by stimulation of the medial perforant path of urethane-anaesthetized rats primed four weeks previously with seven daily injections of nicotine (0.8 mg kg-1 s.c.). The same dose of nicotine did not alter EPSPs evoked in rats primed with saline vehicle. Systemic injection of either mecamylamine or propranolol, 30 min before nicotine challenge, prevented induction of LLP without affecting baseline EPSPs but neither drug affected LLP when given after it was established. Since the nicotine-priming regime is known to increase tyrosine hydroxylase activity and hippocampal noradrenaline release in response to nicotine challenge, the results suggest that systemic injection of nicotine released sufficient noradrenaline in nicotine-primed rats to induce a beta-adrenoceptor-mediated LLP.

Animals↗
PubMed1997

Discrimination of hepatitis G virus/GBV-C geographical variants by analysis of the 5' non-coding region.

We have investigated the ability of different subgenomic fragments to reproduce the phylogenetic relationships observed between six complete genome sequences of GBV-C/hepatitis G virus (HGV). While similar relationships were observed following analysis of part of the 5' non-coding region (5'NCR), for the coding region they were not accurately reproduced for some large fragments or for the majority of fragments of 300 or 600 nucleotides. Analysis of 5'NCR sequences from a large number of isolates, including newly obtained sequences from Pakistan, Zaïre and Scotland, produced separate groupings of Asian, African and European/North American variants. These groupings are associated with specific polymorphisms in the 5'NCR, many of which were covariant and consistent with a proposed secondary structure for this region. The relatively low level of amino acid sequence variation observed between these geographically and phylogenetically defined groups of variants suggests that they are unlikely to display significant biological differences.

Base Sequence↗
PubMed1997

Antigenic variation of core, NS3, and NS5 proteins among genotypes of hepatitis C virus.

Assays that detect antibody to hepatitis C virus (HCV) are used to screen blood donors and patients with hepatitis. Current enzyme-linked immunosorbent assay (ELISA)-based methods are invariably based upon antigens from expressed recombinant proteins or oligopeptides from HCV type 1. Some HCV antigens used in screening assays are coded by regions of the HCV genome that show extensive variability; therefore, HCV type 1-based assays may be less effective for the detection of antibody elicited by infection with other genotypes. In this study, we have measured antibody reactivity of sera from 110 hepatitis C patients infected with type 1b, 3a, or 4a to genotype-specific and cross-reactive epitopes present in recombinant proteins from HCV genotypes 1b (core, NS3, and NS5), 3a (NS3, NS5), and 4a (core, NS3), corresponding to those used in current third-generation screening ELISAs. By comparing the serological reactivities of sera to type-homologous and type-heterologous antigens, we detected a significant type-specific component to the reactivity to NS3 (61 to 77% of the total reactivity) and NS5 (60% of the total reactivity). Furthermore, despite the similarities in the amino acid sequences of the core antigens of type 1b and type 4a, we also found significantly greater reactivity to type-homologous antigens, with approximately 25% of reactivity being type specific. These findings are consistent with previous findings of fivefold weaker reactivity of sera from HCV type 2- and HCV type 3-infected blood donors in the currently used third-generation ELISAs and suggest that these assays are suboptimal for screening populations in which the predominant genotype is not type 1.

Amino Acid Sequence↗
PubMed1997

Prevalence and severity of viral hepatitis in Pakistani pregnant women: a five year hospital based study.

A hospital based observational study was carried out on pregnant women presenting with either acute hepatitis or fulminant hepatic failure (FHF), during the past years. Of 53 patients, 20 (38%) developed FHF.Non-A, Non-B was the commonest cause (62%) followed by hepatitis B in 17% and hepatitis A in 4% cases. Eight women expired (case fatality rate 15%) with a high maternal mortality (62%) caused by NANB hepatitis. Perinatal mortality was 30%. Poor prognostic factors identified were lack of antenatal care, severity of jaundice, history of somnolence, gastrointestinal bleeding and a high grade of encephalopathy.

Adult↗
PubMed1996

The 14.6 kd rubber elongation factor (Hev b 1) and 24 kd (Hev b 3) rubber particle proteins are recognized by IgE from patients with spina bifida and latex allergy.

Two major water-insoluble proteins are located on the surface of rubber particles in Hevea brasiliensis latex. A 14.6 kd protein (Hev b 1), found mainly on large rubber particles (> 350 mm in diameter), and a 24 kd protein (Hev b 3), found mainly on small rubber particles (average diameter, 70 nm), are recognized by IgE from patients with spina bifida and latex allergy. Although Hev b 1 (also called the rubber elongation factor [REF]) has previously been reported as a major latex allergen, this conclusion has been disputed on the basis of results from other studies. The allergenicity of Hev b 1 is verified in this study by testing the recombinant protein generated from its gene. Because allergenicity is confined to patients with spina bifida and not observed in adults sensitive to latex, it is not a major latex allergen. The identification of Hev b 3 as another allergen originating from rubber particles is confirmed by immunogold labeling and electron microscopy. Observations with the monoclonal antibody USM/RC2 developed against Hev b 3 show that the protein has a tendency to fragment into several polypeptides of lower molecular weight (from 24 kd to about 5 kd) when stored at -20 degrees C. There is also indication of protein aggregation from the appearance of proteins with molecular weights greater than 24 kd. Fragmentation of Hev b 3 is induced immediately on he addition of latex B-serum, which is normally compartmentalized in the lutoids in fresh latex. In the preparation of ammoniated latex (used for the manufacture of latex products), the lutoids are ruptured, and the released B-serum reacts with Hev b 3 on the rubber particles to give rise to an array of low molecular weight polypeptides that are allergenic to patients with spina bifida.

Adult↗
PubMed1996

Efficacy of octreotide in diarrhoea due to Vibrio cholerae: a randomized, controlled trial.

Although octreotide, a long-acting analogue of somatostatin, is currently used in the treatment of chronic secretory diarrhoea due to various causes, its role in the management of acute secretory diarrhoea is not well established. In the present study, therefore, the therapeutic value of octreotide in the management of cholera, a classical example of acute secretory diarrhoea, was investigated. During an outbreak of cholera, patients admitted with acute secretory diarrhoea of < or = 24 h duration and a purging rate > 100 ml/h were enrolled on the study and randomly assigned to octreotide (N = 17) and control (N = 16) groups. All 33 patients received intravenous fluid replacement and antibiotic treatment (200 mg ofloxacin twice daily for 3 days, by mouth). Each patient in the octreotide group was also given a subcutaneous injection containing 100 micrograms octreotide every 8 h for a maximum of six doses. The stool output of each patient was recorded every hour until there had been none for an hour, which was taken as the endpoint. Mean (S.D.) total stool output was lower [6.56 (3.7) v. 9.7 (6.5) litres] and the mean (S.D.) duration of diarrhoea after admission was shorter [32.9 (15.6) v. 47.8 (22.3); P < 0.05] in the octreotide group than in the control group. However, as both groups generally had similar purging rates, the higher volume of stools from the control group was simply the result of the longer period of diarrhoea in this group. Octreotide therefore only decreased the duration of diarrhoea in the cholera patients.

Adult↗
PubMed1996

Inferring gender from handwriting in Urdu and English.

Handwriting samples in both English and Urdu from 30 donors were judged for masculinity-femininity by 25 judges (both judges and donors were adult Pakistanis, bilingual and literate in both Urdu and English). Inferences about gender were made reliably and accurately in both Urdu and English. Levels of accuracy (about 68%) were similar to those reported in studies of handwriting in English. Judged gender of handwriting was significantly stable across the two languages studied. These effects are relevant for the study of gender roles and gender stereotyping in assessment.

Adult↗
PubMed1996

Schistosomal-specific nephropathy in Syrian golden hamsters: treatment by induction of antigen excess.

One hundred and twenty Syrian golden hamsters were infected with Schistosoma mansoni cercariae and 20 served as negative controls (group I). Of the S. mansoni-infected hamsters, 20 served as positive controls (group II) and 100 hamsters were treated for 12 weeks post-infection by loading with S. mansoni adult worm antigen. Animals were divided into groups according to the dose of adult worm antigen injected: group III (5-fold increase in circulating antigen concentration), group IV (10-fold increase), group V (20-fold increase), group VI (40-fold increase), and group VII (80-fold increase). Each of the groups was subdivided into four groups (sacrificed at 1, 2, 4 or 7 days after initiation of antigen loading or the corresponding time points in the case of the control groups). At sacrifice, blood and urine were obtained for laboratory assessment (serum creatinine, protein, albumin, cholesterol and urinary proteins). Kidney, liver and spleen tissue specimens were obtained for light, immunofluorescent and electron microscopic examinations. At sacrifice, significant proteinuria, hypoalbuminaemia and hypercholesterolaemia were observed in S. mansoni-infected hamsters when compared with negative control animals. Histopathologic assessment showed changes compatible with those previously reported, mainly immune complex glomerular deposits, mesangial proliferation and renal amyloid deposits. Significant laboratory improvement was observed in animals treated with antigen loading, especially those treated with 80-fold antigen excess and sacrificed at 7 days postinitiation of treatment. Histopathologic evaluation showed significantly less immune complex glomerular deposits, less mesangial hyperplasia, and less amyloid deposits in hamsters treated with antigen loading. It is concluded that induction of antigen excess by antigen loading induces biochemical and histopathologic regression of schistosomal-specific nephropathy in S. mansoni-infected Syrian golden hamsters.

Animals↗
PubMed1996

Effect of anti-schistosomal treatment on schistosomal hepatic pathology: an experimental study in Syrian golden hamsters.

Thirty Syrian golden hamsters were infected with Schistosoma mansoni and 10 were used as negative controls. Hamsters were infected by 100 cercariae; 15 were treated by praziquantel in doses of 100 mg/kg at 12, 13, 14 and 15 weeks postinfection, and 15 hamsters were left as positive control. Five from each subgroup were sacrificed at 24, 28 and 32 weeks after infection. Animals were subjected to weekly analysis for total plasma protein, serum albumin and urinary total protein excretion. At the end point, animals were sacrificed and the mesenteric venous plexus was explored for adult worms. Liver and splenic specimens were examined by light microscopy, and immunofluorescence microscopy. Complete parasite eradication was achieved in the treated animals. Although, there were significantly higher plasma total protein and albumin in the treated group, there was no significant differences in proteinuria. Histopathological examination of liver specimens showed highly significant reduction of granulomas, CAA and CCA, while amyeloid deposition showed minimal reduction in treated animals. Histopathological examination of splenic specimens showed highly significant reduction of fibrosis, granulomas, CAA and CCA, while follicular hyperplasia and amyeloid deposition showed non significant reduction.

Animals↗
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↗
PubMed1996

Schistosoma mansoni hepatic fibrosis in Syrian golden hamsters: effect of dose and duration of infection as shown by immunohistopathological studies.

In this work, 180 Syrian golden hamsters were infected with Schistosoma mansoni and 30 cross matched for age and sex served as control. Infected hamsters were divided into six main groups according to the number of infected cercariae (20, 50, 100, 150, 200 and 250 cercariae). Each group was sub-divided into 5 subgroups, according to the duration of infection after which animals were sacrificed (4, 6, 8, 12 and 24 weeks). Control and infected hamsters were subjected to laboratory evaluation of serum albumin, S. globulin and A/G ratio and histopathological examination of the liver and splenic tissues. A significant reduction of albumin was observed in Schistosma infected hamster (50 cercariae or more) but not in the control ones and those infected with 20 cercariae. There was a significant correlation between these changes and the duration of infection and the number of adult worms recovered from the mesenteric circulation at the end of the experiments. Histopathologic evaluation showed appearance of the circulating schistosome antigens, circulating anodic antigen (CAA), and circulating cathodic antigen (CCA) deposits in the liver by the 14th week after infection; liver granuloma, amyloid deposits, fibrosis, Schistosma pigments as well as inflammatory infiltration was observed at 8-12th week and amyloid deposits, CAA & CCA in the spleen was observed nearly at the same time.

Animals↗
PubMed1995

A nitrocellulose membrane based IgM capture enzyme immunoassay for etiological diagnosis of dengue virus infections.

A nitrocellulose membrane based immunoassay for the detection of dengue virus specific IgM suitable for use in field situations or in peripheral laboratories would be useful for disease surveillance and control. This paper describes such an assay in an IgM capture format (MAC DOT) similar to the microplate based MAC ELISAs currently in use in several research and reference laboratories around the world. The MAC DOT was tested on several sample sets including a retrospective study of 119 patients from Children's Hospital, Bangkok, Thailand, with confirmed dengue infection. The sensitivity of the test was shown to be 94% taking only admission sera into consideration but rising to 99% when both an admission and a discharge specimen were considered. Other sample sets confirmed the high sensitivity and a study of 494 unselected febrile children showed that the specificity of the MAC DOT was 98%.

Journal Article↗
PubMed1995

Comparison of liver histology in chronic active hepatitis C and chronic active hepatitis B.

OBJECTIVE: To study the histological features of chronic active hepatitis C (CAH-C) and to compare these with those of chronic active hepatitis B (CAH-B). METHODS: Thirty-two liver biopsy specimens from patients with chronic active hepatitis and presence of antibodies to hepatitis C on second generation enzyme immunoassay were studied and compared with those in 34 patients with CAH-B. Seventeen of the 32 CAH-C patients had fully developed or developing cirrhosis of liver whereas the remainder had only chronic active hepatitis. RESULTS: Among 32 patients with CAH-C, fatty change (20), Kupffer cell hyperplasia (30), sinusoidal lymphocytosis (27) lymphoid follicles aggregates in portal tracts (26) and bridging necrosis (16) were regular features. Focal necrosis, bile duct necrosis, cholestasis and ground glass cells were however seen much less often. On the other hand, in patients with CAH-B, fatty change (no patient), sinusoidal lymphocytosis (one patient) and lymphoid follicles/aggregates in portal tracts (one patient) were rare. Also, Kupffer cell hyperplasia (22 patients) was seen less commonly in patients with CAH-B as compared to CAH-C. Focal necrosis (34 patients), bile ductular proliferation (9 patients), cholestasis (17 patients) and ground glass cells (15 patients) were more prominent in CAH-B. CONCLUSION: Presence of certain histological features can help in distinguishing between CAH-C and CAH-B.

Adult↗