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Biomedical subjects

M Islam

Publications and source records attributed to M Islam.

At least 19 recordsLinked to original sources
PubMed1997

The increasing burden of disease in Bangladeshi children due to Haemophilus influenzae type b meningitis.

A laboratory-based study of diagnosed bacterial meningitis in the national paediatric hospital identified 852 cases of meningitis in the 8-year period 1987-1994. There were 587 culture-positive cases, of which Haemophilus influenzae (47%) and Streptococcus pneumoniae (32%) accounted for 80%. H. influenzae showed a remarkable increase of 700% during the study period. Most of the H. influenzae cases (90%) occurred in the 1st 2 years of life. Analysis of culture-negative specimens by antigen detection in the last 2 years also revealed the predominance of H. influenzae (71.4%) and S. pneumoniae (22.4%). Typing of H. influenzae isolates during this time showed that 98% of the strains were type b. This retrospective hospital-based study indicated a pronounced increase in the incidence of H. influenzae meningitis and strongly supports the need for large-scale Hib vaccination for young children. However, such nationwide intervention will probably need to be based on a prospective on a prospective and population-based surveillance of H. influenzae infections.

Age Distribution↗
PubMed1997

Comparison of clinical features and pathologic findings in fatal cases of typhoid fever during the initial and later stages of the disease.

This study was undertaken to correlate the clinical features and pathologic changes noted during the initial and later stages of fatal typhoid illness. Five cases who died during the initial stage of the illness (< 2 weeks from onset) had altered mental status, tachypnea, and tachycardia. Three had shock and elevation of serum creatinine values. Autopsies of all five revealed hyperplastic Peyer's patches, features of adult respiratory distress syndrome, and megakaryocytosis. Five other cases died during the later stage of the illness (> or = 2 weeks after onset). They had a left shift in peripheral blood leukocyte count. Autopsies revealed deep ileal ulcerations with or without perforation and peritonitis and intercurrent pneumonia. Three of them had disseminated intravascular coagulation. Further studies are warranted to understand the mediators of shock and tissue injuries during the initial period of the illness.

Adolescent↗
PubMed1996

Correction of metabolic alkalosis by potassium chloride in ectopic adrenocorticotropic hormone syndrome.

A 57-year-old white man presented with metabolic alkalosis, hypokalemia (pH 7.58, HCO3 >50 mEq/L, serum K 1.8 mEq/L) and hypertension. The initial evaluation was significant for markedly elevated serum cortisol and adrenocorticotropic hormone (ACTH) level; neither hormone showed circadian rhythm or suppression with high-dose dexamethasone. Perihilar and supraclavicular masses were found to consist of undifferentiated small cell carcinoma. Ectopic ACTH syndrome was diagnosed. In spite of progressively rising hormone levels (ACTH, 723 pg/dL; and cortisol, 212 microgram/dL), his severe metabolic alkalosis was largely corrected by aggressive treatment with potassium chloride alone. Possible mechanisms of these clinical findings are discussed.

ACTH Syndrome, Ectopic↗
PubMed1996

Randomized trial comparing intermittent antegrade warm blood cardioplegia with multidose cold blood cardioplegia for coronary artery bypass.

Forty patients were randomized to receive antegrade multidose warm (WBC) or cold blood cardioplegia (CBC) during coronary artery bypass. Cardioplegia was infused at a predetermined dose every 10 min during cardioplegia arrest and core temperature was maintained at 37 degrees C in both groups during extracorporeal circulation. Patient profiles were similar in the two groups. Cardiac index, left ventricular stroke work index, and myocardial oxygen consumption were measured before bypass and during the first 7 h of reperfusion. There was no significant difference in myocardial metabolic and function recovery, the incidence of myocardial infarction, low cardiac output or death. Our data suggests that similar protection is provided with the two techniques of myocardial protection.

Coronary Artery Bypass↗
PubMed1996

Interpretation of the Widal test in the diagnosis of typhoid fever in Bangladeshi children.

The value of a Widal test in diagnosing typhoid fever was assessed in children aged between 1 and 10 years in Bangladesh. The test was done on sera specimens from 300 healthy school children, 100 patients with non-typhoidal febrile illness and 150 bacteriologically proven cases of typhoid fever. Salmonella typhi O and H agglutinin titres > 1:80 and > 1:160 were considered to be significant with 88% sensitivity and 98% specificity, respectively. Among the bacteriologically proven cases, 11.3% showed no response to either agglutinin, and in another 17.3% of cases there was no response for TO agglutinin. This study suggests that in children in an endemic area a positive Widal test is of considerable importance in diagnosing typhoid fever. Furthermore, negative results should be interpreted with caution and both the agglutinins must be considered equally important. Reliance on somatic (TO) antigen only will result in missed diagnosis.

Agglutination Tests↗
PubMed1995

Effect of acetylation on conformation and bilirubin-binding properties of goat serum albumin.

Four acetylated derivatives of goat serum albumin with percentage modifications of 18, 40, 53 and 93% were checked for bilirubin-binding and conformational properties. Acetylation caused marked changes in protein conformation, as evidenced by double immunodiffusion and proteolytic digestion results, as well as a decrease in bilirubin binding. An increase in ionic strength had a dramatic effect on the bilirubin-binding characteristics of modified proteins. The results suggest that the lysine residues of goat serum albumin modified in this study are not involved in bilirubin-albumin interaction.

Acetylation↗
PubMed1995

Conjunctival impression cytology fails to detect subclinical vitamin A deficiency in young children.

Thirty-four asymptomatic children, ages 5-35 mo, were studied to compare the conjunctival impression cytology technique with the relative dose response test in detection of subclinical vitamin A deficiency. Conjunctival smears were collected from the infero-temporal-bulbar conjunctiva of each eye with a strip of cellulose acetate filter paper and transferred onto a glass slide. Venous blood was drawn at 0 and 5 h after administration of an oral dose of 1000 micrograms of retinol palmitate (relative dose response test). An increase in serum retinol concentration (> or = 20%) in the 5-h value was considered indicative of an inadequate liver store of vitamin A and hence subclinical vitamin A deficiency. Of the 34 children, 26 (76.5%) had moderate to severe protein-energy malnutrition. Only three children (9%) had abnormal conjunctival impression cytology, whereas 23 (68%) had abnormal relative dose response. Even more striking was the finding that only two of the 23 children with abnormal relative dose response had abnormal conjunctival impression cytology. The results suggest that the conjunctival impression cytology test has poor agreement with the relative dose response test results in assessing vitamin A status in young children. If relative dose response is considered an acceptable reference method for assessing vitamin A status, then the conjunctival impression cytology test cannot be considered a valid measure of subclinical vitamin A deficiency in this population.

Bangladesh↗
PubMed1995

Development of an improved animal model of shigellosis in the adult rabbit by colonic infection with Shigella flexneri 2a.

Rabbits are not usually susceptible to intestinal Shigella infection without extensive pretreatment, including starvation and administration of antimicrobial, antimotility, and toxic agents (carbon tetrachloride). Most animals infected this way die rapidly and do not always develop colonic lesions and signs of dysentery. We describe here a successful experimental infection in the adult rabbit which does not require preparatory treatment and which reproduced characteristic features of human shigellosis. Unstarved, untreated adult rabbits were infected by direct inoculation of virulent Shigella flexneri 2a (10 ml of 10(7) bacteria per ml) into the proximal colon after ligation of the distal cecum (cecal bypass). Within 24 h of infection, most inoculated animals consistently developed clinical dysentery, characterized by liquid stool mixed with mucus and blood, leukocytosis, anorexia, and weight loss. Histologically, there were edema, exudation, superficial ulceration, and polymorphonuclear infiltrations in the lamina propria; crypt abscess formation; focal hemorrhages; and the presence of immunohistochemically stained S. flexneri in the colonic mucosa. Successful bacterial colonization was indicated by the isolation of the challenge strain of S. flexneri 2a from the colonic contents. None of the control rabbits challenged with nonvirulent S. flexneri or without cecal bypass developed dysentery or colitis. We conclude that successful Shigella infection can be induced by direct colonic inoculation with virulent S. flexneri 2a in adult rabbits without starvation and pretreatment. The colitis is dependent on the virulence of the bacteria and on the cecal bypass. This model should be useful in studies of the immunopathogenesis of Shigella infection.

Animals↗
PubMed1994

Involvement of lysine residues of goat serum albumin in high-affinity binding of bilirubin.

Four maleylated derivatives of goat serum albumin having percent modification as 40%, 46%, 84% and 98% were prepared using varying molar ratio of maleic anhydride over protein. These preparations were found to be pure, both with respect to size and charged as judged by gel filtration and polyacrylamide gel electrophoresis. Maleylation caused significant change in protein conformation as revealed by the change in Stokes radius and frictional ratio of serum albumin, from 3.46 nm and 1.28 to 4.96 nm and 1.79, respectively, upon 98% modification. Immunodiffusion results of native and modified albumins with anti-goat serum albumin antiserum also suggested significant conformational changes in serum albumin upon maleylation. About 88% reduction in bilirubin binding was observed after modification of 98% amino groups of serum albumin as studied by visible difference spectroscopy at pH 8.0, and at 0.15 ionic strength. Increase in ionic strength to 1.0 did not lead to any significant reversal in bilirubin binding. These results prove the involvement of lysine residues in bilirubin-albumin interaction.

Acylation↗
PubMed1994

Alteration in vascular reactivity in isolated aortic rings from portal vein-constricted rats.

It has been suggested that increased production of nitric oxide by an inducible nitric oxide synthase isoenzyme is important in the pathogenesis of the vascular abnormalities seen in human beings and animals with portal hypertension. We investigated this hypothesis by studying the in vitro vascular reactivity of isolated aortic rings from portal vein-constricted and sham-operated rats. Aortic rings from portal vein-constricted rats exhibited significantly impaired contractility to phenylephrine and potassium chloride compared with control rats. Preincubation with the nitric oxide synthase inhibitor nitro-L-arginine methyl ester significantly increased contractility to phenylephrine and potassium chloride in both portal-hypertensive and control tissues, with greater effect in the portal-hypertensive rings. Despite nitro-L-arginine methyl ester, maximal contractions were still significantly smaller in the portal-hypertensive tissues. Vascular relaxation evoked by acetylcholine, but not by the endothelium-independent vasodilator glyceryl trinitrate, was significantly impaired in the portal-hypertensive group. Our results demonstrate significant impairment in vascular function in aortic rings in this model of portal hypertension. The addition of a nitric oxide synthase inhibitor partly corrected these changes, suggesting that although nitric oxide is likely an important mediator, other factors may also be involved in the pathogenesis of these alterations in vascular function.

Acetylcholine↗
PubMed1994

Influence of systemic hypothermia on systolic and diastolic functional recovery after continuous warm antegrade blood cardioplegia.

Experimental observations in our laboratory indicate that myocardial recovery is similar following warm or cold antegrade blood cardioplegia when the core temperature is maintained at 37 degrees C. To determine the effects of hypothermia on myocardial recovery, 15 adult mongrel dogs were randomized to normothermic or hypothermic bypass (28 degrees C) during 60 min of continuous warm antegrade blood cardioplegia. The hypothermic group was rewarmed after releasing the aortic cross-clamp and bypass was discontinued at 30 min in both groups. Myocardial recovery was assessed at 60, 90, and 120 min after the arrest. Core temperature was maintained in the normothermic group but gradually decreased after bypass in the hypothermic group, reaching a low of 33.8 +/- 1 degrees C at 120 min. Myocardial functional recovery was preserved after normothermic bypass. The decrease in core temperature, however, that was observed after systemic hypothermia, was paralleled by significant decreases in the maximum rate of left ventricular pressure rise (dp/dt), the maximum elastance of the left ventricle, and preload recruitable stroke work. Diastolic function decreased slightly, but not significantly, during reperfusion following systemic hypothermia but was unaltered after normothermic bypass. Myocardial oxygen consumption was unchanged in both groups. Myocardial ultrastructure was preserved after normothermic bypass. In contrast, cellular oedema and mild ultrastructural changes were evident after systemic hypothermia. We therefore conclude that the use of systemic hypothermia during bypass is associated with lower core temperatures during early recovery which results in impaired functional recovery.

Animals↗
PubMed1993

Rapid detection of Shigella dysenteriae and Shigella flexneri in faeces by an immunomagnetic assay with monoclonal antibodies.

A rapid and sensitive method for the detection of Shigella dysenteriae type 1 and Shigella flexneri serotypes in faeces based on capture of the bacteria with immunomagnetic particles is described. The particles were coated with either of two different monoclonal antibodies specific for the O-antigens of Shigella dysenteriae type 1 and Shigella flexneri serotypes. Captured bacteria were detected by an enzyme immunoassay with O-antigen specific rabbit antiserum. The whole assay required 2 to 3 hours to perform and the sensitivity limit was 10(3) cfu/ml as determined by viable cell counting. One hundred and fifty enterobacteria strains, including 100 Shigella strains from a strain collection, and 302 fresh faecal samples were used for the study. All Shigella dysenteriae type 1 and Shigella flexneri culture-positive faecal samples were positive in the immunomagnetic assay. In addition 18 of 252 culture-negative faecal samples were positive. The immunomagnetic assay was compared with latex agglutination and indirect immunofluorescence using culture as the reference method. The immunomagnetic assay had a sensitivity of 100%, latex agglutination a sensitivity of 72% with 28% false-negative results, and indirect immunofluorescence a sensitivity of 95%. The immunomagnetic assay was superior in sensitivity since it also detected Shigella in faecal samples up to two days after antibiotic therapy had been started, which both latex agglutination and indirect immunofluorescence failed to do. The high sensitivity in detecting live and dead bacteria, and the ease of performance of the immunomagnetic assay render it an attractive method for detection of Shigella.

Animals↗
PubMed1993

Probing the determinants of protein solubility with amino acid modification.

Chemical modification was used as a probe to study the effect of structural features of serum albumin (charge, conformation, surface hydrophobicity, etc.) on its solubility behavior in concentrated ammonium sulfate solutions. Four different acetylated derivatives of goat serum albumin namely 18% acetylated, 40% acetylated, 53% acetylated, and 93% acetylated albumins were prepared. The homogeneity of these preparations was established by gel chromatography and polyacrylamide gel electrophoresis. Hydrodynamic data on the Stokes radius of native and acetylated albumins suggested gradual change in conformation on increasing modification. Solubility experiments performed in concentrated ammonium sulfate solutions at pH 7.0 and at 30 degrees C showed a slight decrease in salting-out parameter, Ks, up to 40% modification, whereas a significant decrease was obtained at higher modification. However, the salting-out parameter, beta, decreased monotonously. Similar decrease in these parameters was also observed with different modified albumins at other pH values viz. pH 5.5, 4.5, and 3.6. From these results we conclude that the decrease in solubility of serum albumin on increasing modification was primarily due to change in conformation.

Acetylation↗