Search PubMed⌕ Search

Biomedical subjects

F Ahmed

Publications and source records attributed to F Ahmed.

At least 127 records · Page 7Linked to original sources
PubMed1990

Field trial of oral cholera vaccines in Bangladesh: evaluation of anti-bacterial and anti-toxic breast-milk immunity in response to ingestion of the vaccines.

In a field trial conducted in Bangladesh, ingestion of either B subunit-killed whole cell (BS-WC) or killed whole cell (WC) oral cholera vaccines by mothers was associated with a 47% reduction of the risk of cholera in their non-vaccinated children aged under 36 months. Because vaccine-induced breast-milk immunity seemed a possible explanation for these findings, we evaluated anti-lipopolysaccharide (LPS) and anti-cholera toxin (CT) IgA antibody responses in breast milk collected during the trial from 53 lactating women who ingested three doses of BS-WC, WC, or an Escherichia coli K12 strain (K12). Despite induction of moderate vibriocidal (1.4 to 2.0-fold) and anti-CT (4.5-fold) serum antibody responses, the vaccines did not elicit significant rises of anti-LPS or anti-CT IgA breast-milk antibodies. The failure of the vaccines to elicit significant levels of breast-milk anti-cholera antibodies suggests an alternative explanation for protection of young children by maternal vaccination, such as interruption of maternal-child transmission of Vibrio cholerae 01.

Administration, Oral↗
PubMed1990

The interaction of vitamin A deficiency and rotavirus infection in the mouse.

Weanling mice were fed on a control diet ad lib., a vitamin A-deficient diet ad lib. or pair-fed to the intake of the vitamin A-deficient group. Vitamin A deficiency was induced by 63-70 d of age. On day 77 mice were given 30 microliters rotavirus/mouse orally and examined histologically 1 week later. There were no changes in relative liver weight in any of the groups, but following infection animals deficient in vitamin A showed a significant increase in spleen weight compared with the other groups. The relative weight of the thymus was reduced by vitamin A deficiency, in both non-infected and infected animals. The histology of the spleen, thymus and small intestine was similar in all three dietary groups before infection. The number of goblet cells per duodenal villus in vitamin A-deficient animals was significantly lower than that of control and pair-fed animals. In the small intestine of vitamin A-deficient animals, rotavirus infection caused dramatic changes to the mucosa, with almost complete destruction of the tips of the villi, but control and pair-fed animals had normal villi. It is concluded that although rotavirus infection and vitamin A-deficiency cause few changes alone, in their action together there is significant destruction of the mucosal barrier of the small intestine.

Animals↗
PubMed1990

Seroepidemiologic evaluation of anti-toxic and anti-colonization factor immunity against infections by LT-producing Escherichia coli in rural Bangladesh.

To evaluate serologic immunity against clinical infections by heat-labile enterotoxin-producing Escherichia coli (LT-ETEC) in rural Bangladesh, 124 children and adult women with LT-ETEC diarrhea (cases) were compared with 347 age-matched community controls. In paired acute-convalescent sera from the cases, IgG anti-CFA I and anti-CFA II antibody titers increased eight-to ninefold after infection by LT-ETEC with the homologous CFA, and IgG anti-LT antibody titers increased fourfold for all LT-ETEC infections. Anti-CFA and anti-LT titers peaked in controls aged 12-23 months, the age group with the highest incidence of ETEC infections. However, antibody titers were similar in acute sera from cases and in sera from controls. Although serum IgG anti-CFA and anti-LT antibodies rose in response to LT-ETEC infections and paralleled the age-specific incidence of ETEC in the community, these antibodies were not associated with a lower risk of LT-ETEC diarrhea.

Adolescent↗
PubMed1990

Excessive faecal losses of vitamin A (retinol) in cystic fibrosis.

Vitamin A (retinol) deficiency is a recognised complication of cystic fibrosis and is presumed to be a consequence of an impairment in the digestion and absorption of dietary fats. The dietary intake of fat and retinol was assessed from a seven day weighed food intake in 11 subjects with cystic fibrosis and 12 matched controls. Faecal excretion of retinol and fat were measured from three day stool collections. There was little difference between the two groups in the intake of fat or retinol equivalents. When studied the subjects with cystic fibrosis were clinically stable and the apparent absorption of fat was not significantly different to that in the controls. There was a significant increase in the faecal losses of retinol in cystic fibrosis, which was unrelated to the degree of fat in the stool. In cystic fibrosis the median retinol recovered in the stool was 40% of the intake, compared with 1.8% in the controls. It is concluded that there is a specific defect in the handling of retinol by the gastrointestinal tract in cystic fibrosis, which may be unrelated to the digestion and absorption of dietary fat.

Adolescent↗
PubMed1990

Effect of undernutrition on the immune response to rotavirus infection in mice.

The effect of moderate and severe undernutrition on the immune response to EDIM rotavirus was studied in mice. A moderate state of undernutrition was produced by feeding weanling mice either 15 or 30% less diet than the control group had eaten on the previous day, for 7 weeks. After 6 weeks, mice were given 30 microliters/mouse of EDIM rotavirus orally and the antibody production was measured 1 week later. The delayed-type hypersensitivity (DTH) response to picryl chloride (PC) was measured as an index of cell-mediated immunity. For severe undernutrition, weanling mice were fed either 30 or 50% less diet than the control group had eaten on the previous day, for 12 weeks. After 11 weeks of feeding, animals were given 30 microliters/mouse of EDIM rotavirus either orally or intramuscularly and the antibody production was measured 1 week later. In moderate undernutrition, the serum antibody levels specific to rotavirus and the DTH response to PC were normal in all dietary groups compared with the control group. In severe undernutrition, the antibody levels following oral challenge of rotavirus were similar in all dietary groups. There was a significant impairment of serum antibody levels following intramuscular challenge in the group fed 50% less than the control group. It is concluded (1) that a balanced reduction in food intake does not impair the immune response, unless severe restriction is maintained for a long period of time, and (2) that the antibody response varies with the route of immunization.

Animals↗
PubMed1990

Factors associated with not receiving adequate prenatal care in an urban black population: program planning implications.

REcords of 36,608 Black single live births and 762 infant deaths in Washington, D.C., from 1980 to 1985 were analyzed. Bivariate and multivariate contingency table analysis were carried out to identify the groups at high risk for not obtaining adequate prenatal care. Results show that the groups of mothers which are less likely to receive adequate care also have a high risk of delivering low birthweight infants even when they receive adequate care. The paper focuses on women with high gravidity and short birth intervals for in-depth analysis of programming needs.

Black or African American↗
PubMed1990

Site predilection of oral cancer and its correlation with chewing and smoking habit--a study of 103 cases.

Like many other countries in South East Asia, oral cancer is one of the common cancers in Bangladesh. This report is based on one hundred and three cases of biopsy proven squamous Cell Carcinoma of the oral cavity collected from different Medical Institutions in Dhaka. The aim was to find out relationship between chewing and smoking habit and anatomic site of the cancer in oral cavity. It has been observed that oral cancers are common in older age groups and the proportion is higher in males as compared to females. Buccal mucosa has been the commonest site, the next being the anterior two-thirds of tongue. A high percentage of patients revealed tobacco habits in the form of chewing with betel quid and or smoking. Both smoking and chewing were found to be important in males in all the anatomical sites and chewing of tobacco with betel quid appeared to play a dominant role in the females. Duration of betelquid chewing and smoking seem important. Site of origin of the majority of the lesions corresponded with site maximally exposed to betelquid with or without incorporation of tobacco. In majority of the cases the cancer was well differentiated.

Adult↗
PubMed1989

Lysosomal mutations increase susceptibility to anaesthetics.

The anaesthetic responses of homozygous mutant mice were compared with those of their normal heterozygous littermates. The two recessive mutations studied were beige (bg) and reduced pigmentation (rp). Homozygosity for either significantly increased the sleeping time of both sexes after treatment with pentobarbital, tribromoethanol or the steroid anaesthetic alphaxalone.

Anesthesia↗
PubMed1989

Exclusion of clinically atypical or microbiologically mixed diarrhoeal episodes from outcome events in a field trial of oral cholera vaccines.

We investigated whether alternative clinical and microbiological criteria for outcome events affected estimates of vaccine efficacy in a randomized, double-blind field trial of B subunit-killed whole cell (BS-WC) and killed whole cell-only (WC) oral cholera vaccines among 62,285 rural Bangladeshi participants. At one year of follow-up estimates of vaccine protective efficacy (PE = 60%, P less than 0.0001 for BS-WC; PE = 54%, P less than 0.0001 for WC) against all treated diarrhoeal episodes associated with V. cholerae 01 were similar to estimates of efficacy against only those episodes which were clinically typical and unassociated with additional enteric pathogens (PE = 62%, P less than 0.0001 for BS-WC; PE = 52%, P less than 0.0001 for WC). In contrast, estimates of vaccine cross-protection against episodes associated with each of several agents antigenically related to V. cholerae 01 (LT-ETEC, non-cholera Vibrio sp, Aeromonas sp) were substantially reduced when mixed infections with V. cholerae 01 were excluded. We conclude that restrictive criteria intended to improve the specificity of the definition of cholera did not increase the detectability of vaccine efficacy against V. cholerae 01, but that exclusion of mixed infections with V. cholerae 01 was necessary to avoid false-positive conclusions about vaccine cross-protection against other potential target pathogens.

Administration, Oral↗
PubMed1989

Urban-suburban differences in the incidence of low birthweight in a metropolitan black population.

To study the urban-suburban differences in low birthweight among black Americans, 54,870 single births occurring to black mothers in the hospitals of Washington, DC, from 1980 to 1984 were analyzed. The observed data showed a 25% higher incidence of low birthweight (under 2501 gm) among infants born to urban mothers compared with those born to suburban mothers. Bivariate analysis showed that a greater proportion of urban mothers, compared with the proportion of suburban mothers, was teenage (23.6% vs 10.3%) and unmarried (67.6% vs 32.9%), had less than a high school education (31.7% vs 9.1%), and received inadequate prenatal care (34.3% vs 20.3%). The logit model fit to these data showed that by controlling for the above risk factors, the residential differences in the incidence of low birth rate were almost eliminated. Exploration of the medical risks associated with adverse pregnancy outcomes showed that the urban mothers had substantially higher rates for premature rupture of membrane, concurrent hypertension, pre-existing diabetes, hyperemesis, anemia, and narcotic addiction. The findings of the article underline the usefulness of studying intra-black differences rather than relying solely on race comparative research.

Black or African American↗
PubMed1988

Impact of B subunit killed whole-cell and killed whole-cell-only oral vaccines against cholera upon treated diarrhoeal illness and mortality in an area endemic for cholera.

The impact of B subunit killed whole-cell (BS-WC) and killed whole-cell-only (WC) oral cholera vaccines was assessed in a randomised double-blind trial in rural Bangladesh. 62,285 children aged 2-15 years and women aged over 15 ingested three doses of one of the vaccines or placebo. During the first year of follow-up there was a 26% reduction of all visits for treatment of diarrhoea in the BS-WC group and a 22% reduction in the WC group. The reduction of all admissions for fatal or severely dehydrating diarrhoea was 48% in the BS-WC group and 33% in the WC group. Overall mortality rates were 26% lower in the BS-WC group and 23% lower in the WC group during the first year, and reductions of mortality were observed only in women vaccinated at ages over 15 years. However, no differences in cumulative mortality were evident at the end of the second year of surveillance.

Administration, Oral↗
PubMed1988

The removal of exogenous thiols from proteins by centrifugal column chromatography.

Centrifugal column chromatography was shown to provide a rapid, efficient, and useful means of separation of various low molecular weight thiols from proteins. The single chromatographic step procedure employed standard 5 ml plastic syringes containing Sephadex G-25 as the bed matrix and required less than 5 min to produce average dilutions of 5000-, 980-, and 25-fold, respectively, from 5 to 200 mM initial concentrations of 2-mercaptoethanol, dithiothreitol, and reduced glutathione in the sample as measured by titration with 5,5'-dithiobis-(2-nitrobenzoic acid). Dihydrofolate reductase solutions of 0.07-0.08 mM were separated from 50 mM 2-mercaptoethanol, dithiothreitol, or reduced glutathione with a minimum 16,500-fold dilution of the thiol after centrifugal chromatography on two consecutive columns. Thymidylate synthase solutions of 0.06 mM were effectively separated from 50 mM 2-mercaptoethanol or dithiothreitol with a minimum average 5900-fold dilution of the thiol after consecutive column chromatography. There was no change in either the physical or chemical properties of the enzyme throughout the course of the experiments as determined by activity, active site sulfhydryl group titration, and binding assays. Recoveries of protein obtained in the load fraction were usually in excess of 70% of the protein loaded with virtually no dilution from the initial concentration. This method was developed in order to facilitate the study of the active site sulfhydryl groups in enzymes.

Centrifugation↗
PubMed1988

Field trial of oral cholera vaccines in Bangladesh: results of one year of follow-up.

We assessed the protective efficacy (PE) of three doses of B subunit-killed whole cell (BS-WC) and killed whole cell-only (WC) oral cholera vaccines in a randomized, double-blind trial among 62,285 children and women residing in rural Bangladesh. After one complete year of surveillance, 110 cases of cholera were detected in the placebo group, 52 in the WC group (PE, 53%; P less than .0001), and 41 in the BS-WC group (PE, 62%; P less than .0001). Protection was greater for BS-WC recipients than for WC recipients only during the initial eight months of observation. Both vaccines conferred equivalent protection against cholera associated with life-threatening dehydration and against less severe cholera. High-grade, sustained protection was observed in persons vaccinated when older than five years; in younger persons protection was transient. We conclude that BS-WC and WC vaccines confer significant protection against cholera, particularly in persons vaccinated when older than five years.

Administration, Oral↗
PubMed1987

Hypolipidemic activity of trimethylamine-carbomethoxyborane and related derivatives in rodents.

A number of substituted amine-carboxyborane esters were examined for their hypolipidemic activity in rodents. Trimethylamine-carbomethoxyborane, Me3NBH2C(O)OMe, was observed to be the most effective hypolipidemic agent in the rodent at the low dose of 8 mg/kg/d. This agent effectively increased the high density lipoprotein (HDL) cholesterol content and lowered the low density lipoprotein (LDL) cholesterol and triglyceride contents of rat lipoproteins. Furthermore, the agent accelerated cholesterol excretion from the body of the rat and reduced the activity of the rate-limiting enzyme involved in the de novo synthesis of lipids in the liver. The agent has a safe therapeutic index, and appeared to have more promise as a therapeutic agent than other borane esters.

Animals↗
PubMed1987

B subunit-whole cell and whole cell-only oral vaccines against cholera: studies on reactogenicity and immunogenicity.

We conducted a randomized trial among persons in rural Bangladesh to evaluate the side effects and immunogenicity of orally administered B subunit-killed whole cell (BS-WC) and killed whole cell-only (WC) cholera vaccines and a killed Escherichia coli strain K12 placebo proposed for field testing. Three doses of BS-WC, WC, E. coli, or a control agent were given with antacid to 1,257 women (aged greater than 15 years) and children (aged to to 15 years). The four groups exhibited no statistically significant differences in occurrence of symptoms after each dose, and rises in titers of vibriocidal (VC) antibodies to Inaba and Ogawa were twofold higher for vaccinees than for controls (P less than .001). Half of the persons with fourfold or greater VC responses to WC responded after the first dose; many additional patients, particularly young children, responded after subsequent doses. In contrast, 89% of persons who responded to BS-WC with twofold or greater rises in titer of IgG antibodies to cholera toxin did so after the first dose. After the third dose, vaccinees exhibited a fivefold higher rise in titer than did controls (P less than .001); a dose-to-dose booster effect was most evident in young children.

Administration, Oral↗
PubMed1987

Deep venous thrombophlebitis: detection with 4-hour versus 24-hour platelet scintigraphy.

Thirty-one nonheparinized patients with suspected deep venous thrombophlebitis (DVT) underwent contrast venography and indium-111 platelet scintigraphy (In-111 PS). Venography permitted identification of acute DVT in 12 of 31 cases (39%). One additional patient was considered to have acute DVT despite nonconclusive venography results. In-111 PS results were positive at 4 hours in nine of 13 cases (69%) and at 24 hours in 12 of 13 cases (92%). Two of four patients with false-negative 4-hour In-111 PS studies had received warfarin. Thus, the sensitivity of 4-hour In-111 PS in patients not receiving anticoagulants was 82%. Venography results were negative for acute DVT in 18 cases, and 4-hour In-111 PS studies were negative or equivocal in each. In-111 PS is an alternative to contrast venography for detecting acute DVT. If 4-hour In-111 PS results are positive, anticoagulation can be initiated. Delayed images are necessary if the 4-hour images are negative or equivocal.

Aged↗