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Biomedical subjects

S Ahmed

Publications and source records attributed to S Ahmed.

At least 91 records · Page 5Linked to original sources
PubMed2002

Amplified fragment length polymorphism (AFLP) analysis of Clostridium novyi, C. perfringens and Bacillus cereus isolated from injecting drug users during 2000.

As part of the follow-up investigations associated with an outbreak of severe illness and death among illegal injecting drug users during 2000, 43 cultures of Clostridium novyi type A, 40 C. perfringens type A and 6 isolates of Bacillus cereus were characterised by amplified fragment length polymorphism (AFLP) analysis. Among the 43 C. novyi isolates, 23 different AFLP profiles were detected. The same AFLP profile was detected in isolates from 18 drug users investigated during 2000 from Scotland, England, the Republic of Ireland and Norway and a wound from a patient in 2000 who was not identified as a drug user. Unique AFLP profiles were obtained from four drug users from England and the Republic of Ireland, 10 historical isolates from culture collections, an isolate from food (1989) and three isolates from wounds (1995, 1991, 1988). The 40 C. perfringens isolates were from 13 drug users, the contents of one syringe and two samples of heroin. Sixteen AFLP types of C. perfringens were distinguished and there was little evidence for commonality among the isolates. The AFLP types of C. perfringens from heroin differed and were unique. Six isolates of B. cereus were from four drug users and two samples of heroin. Four different AFLP patterns were distinguished. Three AFLP types were isolated from four drug users. B. cereus isolates from an aspirate and a heroin sample collected from the same drug user were identical, and were also indistinguishable from an isolate from a groin infection in a second drug user. The AFLP type of the isolate from a second and unrelated heroin sample was unique. The AFLP results showed no or very limited evidence for commonality between the different isolates of B. cereus and C. perfringens. In marked contrast, the C. novyi isolates from the majority of the drug users during 2000 were homogeneous, suggesting a common source or clonal selection of a C. novyi type, or both, which either had an adaptive advantage in spore germination, survival or growth following the drug preparation and the injection procedure, or produced a more severe clinical presentation.

Animals↗
PubMed2002

Fulminant ischaemic colitis with atypical clinical features complicating sickle cell disease.

Clinically significant ischaemic bowel injury is an exceedingly rare complication of sickle cell disease. It manifests as acute surgical abdomen and may respond to conservative treatment. An unusual fatal case of ischaemic colitis with minimal abdominal findings in a young male during a sickle cell vaso-occlusive pain crisis is described. This case demonstrates that an acute surgical abdomen should be considered in such patients who fail to respond to conservative management as untreated this condition may be fatal.

Abdomen, Acute↗
PubMed2002

HIV associated thrombotic microangiopathy.

Thrombotic microangiopathy (TMA) is a known complication of HIV infection. Endothelial cell injury appears to be the primary event causing platelet activation and deposition in the microvasculature. Direct cytopathic roles of HIV as well as other factors such as malignancy, drugs, and infectious agents have been implicated in the pathogenesis of HIV-TMA. Although the the majority of patients present in a more advanced stage of HIV disease, TMA can be the initial presenting symptom of HIV infection. Clinical features are those of idiopathic TMA, and the diagnosis should be suspected in any patient with new onset thrombocytopenia and microangiopathic haemolytic anaemia. Therapy with plasma exchange or infusion appears to be efficacious. A rapid diagnosis and institution of plasmapheresis is crucial for a favourable outcome. The long term prognosis of HIV-TMA is unfavourable and may depend on the stage of HIV infection. The recent data after the use of highly active retroviral treatment, however, are unavailable and current prognosis is therefore uncertain.

Diagnosis, Differential↗
PubMed2002

Ghrelin: a hypothalamic GH-releasing factor in domestic fowl (Gallus domesticus).

Ghrelin, a recently discovered peptide in the mammalian hypothalamus and gastrointestinal tract is thought to be the endogenous ligand for the GH secretagogue (GHS) receptor and it stimulates GH release in rats and humans. The possibility that ghrelin is present in birds was therefore assessed, since a GHS receptor is present in the chicken pituitary gland. Although immunoreactive ghrelin is readily detectable in the rat stomach and ileum, ghrelin immunoreactivity could not be detected in the chicken proventriculus, stomach, ileum or colon, whereas somatostatin immunoreactivity, in contrast and as expected, was readily detectable in the chicken gastrointestinal tract. Ghrelin immunoreactivity was, however, present in the chicken hypothalamus, although not in the arcuate (infundibular) nucleus, as in rats. Discrete parvocellular cells and neuronal fibers with ghrelin immunoreactivity were present in the anterior medial hypothalamus. This immunoreactivity was specific and completely abolished following the preabsorption of the antibody with an excess of human ghrelin. Ghrelin immunoreactivity was also present in clusters of large ovoid magnocellular cells in the nucleus magnocellularis preopticus pars medialis, nucleus magnocellularis preopticus supraopticus and in the chiasmaopticus. Immunoreactivity for ghrelin was restricted to the cytoplasm of the perikarya and their axonal sprouts. Immunoreactivity for ghrelin was not seen in any other hypothalamic nuclei. In a preliminary experiment, circulating GH concentrations in conscious immature chicks were promptly increased following bolus i.v. administration of human ghrelin. The increase in GH concentration (approximately three times that in the controls) was comparable with that induced by the same dose (10 microg/kg) of human GH-releasing hormone, although less than that (approximately sixfold) induced by thyrotropin-releasing hormone. These results demonstrate the presence of a ghrelin-like protein in the chicken hypothalamus and suggest that it participates in the regulation of GH secretion in birds.

Animals↗
PubMed2002

Evidence for genomic and nongenomic actions of estrogen in growth plate regulation in female and male rats at the onset of sexual maturation.

Recently, both estrogen receptor (ER) alpha and beta were detected in growth plate chondrocytes of rats before sexual maturation, implying a role for estrogen at this stage. In this study, therefore, we investigated the effects of ovariectomy (OVX) or estrogen supplementation on parameters of longitudinal growth in 26-day-old rats, which were sexually immature at the start of the experiment. OVX caused an increase in body weight gain, tibial length and growth plate width due to an increased proliferating zone. This increase correlated with an increase in cell number, with a decrease in cell diameter and with increased proliferating cell nuclear antigen (PCNA) immunostaining compared with sham. Interestingly, the increase in proliferation was not caused by an increase in insulin-like growth factor-I (IGF-I) mRNA expression in the growth plate as assessed by real-time PCR. In contrast to OVX, 17beta-estradiol (E(2)) supplementation (0.5 mg/21 days) of 26-day-old female rats caused a strong decrease in body weight gain, tibial length and growth plate width. The latter was explained by a reduction of the proliferating zone width, which correlated with a reduced number of PCNA-positive cells (not significant) and by a reduction of the hypertrophic zone width. In male rats supplemented with E(2), similar effects were observed compared with the females. ERalpha and beta immunostaining was found predominantly in late proliferating and early hypertrophic chondrocytes. OVX did not affect ER expression but E(2) supplementation strongly decreased immunostaining for both ERalpha and beta in both sexes. Besides E(2), desoxyestrone (DE), an activator of nongenomic estrogen-like signaling (ANGEL) and 2-methoxyestradiol (2-MeO-E(2)), a tissue-selective naturally occurring metabolite of E(2), were administered to female and male rats of the same age. Compared with E(2), these compounds had less pronounced, though significant, effects on some parameters of longitudinal growth in both sexes, especially on growth plate characteristics. In conclusion, E(2) may exert effects on longitudinal growth before and at the onset of sexual maturation, despite very low endogenous serum levels at these stages. There may be a role for nongenomic signaling in body weight gain, tibial length and growth plate width but genomic signaling prevails.

2-Methoxyestradiol↗
PubMed2002

Chronic carriers of hepatitis B virus in Bangladesh: a comparative analysis of HBV-DNA, HBeAg/anti-HBe, and liver function tests.

Serological markers of hepatitis B virus (HBV), liver function tests and quantitative estimation of HBV-DNA are important in the assessment of the state of infection and prognosis following treatment for hepatitis B. This study aimed to determine whether low-cost assays, eg hepatitis B e antigen (HBeAg) and liver function tests, could be used for the assessment of infectivity as an alternative to HBV-DNA estimation. We tested 125 hepatitis B carriers for HBeAg, antibody to HBeAg (anti-HBe), and serum HBV-DNA; we also carried out a range of standard liver function tests. Seventy-three subjects were positive and 52 were negative for HBeAg. Of the HBeAg positive cases, 3 were also positive for anti-HBe; of the HBeAg negative cases, 5 were also negative for anti-HBe. Of these 8 cases, 7 had no detectable HBV-DNA. Most of the HBeAg positive but anti-HBe negative subjects were positive for HBV-DNA (74.3%; 52/ 70) whereas most of the HBeAg negative and anti-HBe positive subjects (93.6%; 44/47) were also negative for HBV-DNA. Of 56 HBV-DNA positive individuals, alanine transaminase (ALT) was found to be raised in 69.6% (p=0.066) and aspartate transaminase (AST) was raised in 66.1% (p=0.011), while 67.9% had normal alkaline phosphatase (ALP) (p=0.054). HBeAg (p=0.018) and raised ALT (p=0.008) were found to be independent predictors for HBV-DNA positivity among HBV carriers. This study suggests that HBeAg positive and anti-HBe negative hepatitis B carriers with raised ALT and AST are likely to be positive for HBV-DNA; the combination of routine serology and biochemical tests may be considered as an alternative to HBV-DNA in evaluating the state of chronic HBV infection. However, HBV-DNA should be specifically assessed if discordance is observed between seromarkers and transaminases.

Adolescent↗
PubMed2002

Alpha-1 antitrypsin deficiency in emphysema.

Human plasma contains a number of proteinase inhibitors which together form 10% of the total plasma proteins. Serine proteases are a group of closely related proteolytic enzymes, with serine in their active site. These play a key role in coagulation, fibrinolysin, kinin and complement activation. Serine protease inhibitors or "serpins" are specific inhibitors which control the activities of these enzymes. Among the serine protease inhibitors. Alpha-1 antitrypsin (alpha1 ATD) is found in highest concentration in plasma. It is the major physiologic inhibitor for neutrophil elastase. It has control over the elastase mediated degradation of elastic tissue in the lung. Alpha1ATD deficiency is a common genetic disorder and potentially lethal disease predominantly found in North European population--where the incidence is one in 2500; worldwide figures suggest that one in 6000 people have classic alpha1ATD. In cases of deficiency, antielastase activity is reduced in the lungs which results in increased elastin breakdown and development of emphysema. Cigarette smoking contributes to destructive changes in emphysema by suppressing the proteinase inhibitory activity of human serum and by inducing certain bronchoalveolar changes. Prevalence and severity of asthma increases in persons with abnormal alpha1ATD phenotype.

Humans↗
PubMed2002

Extended-spectrum beta-lactamases in Enterobacteriaceae: related to age and gender.

The prevalence of extended-spectrum beta-lactamases producing Enterobacteriaceae (ESBLPE) among nosocomial and community acquired isolates was studied (September, 1999 - August, 2000). Nosocomial and OPD isolates (200 each) were collected from OPD and different wards of the Pakistan Institute of Medical Sciences (PIMS) Islamabad, Pakistan, and tested for the production of ESBLs using the double disc diffusion technique. The prevalence of ESBL was highest in nosocomial isolates among the patients of age group III (50-60 years) (48%) with Escherichia coli as the most prevalent organism. ESBL positive isolates were mostly reported in males (65.33%) compared to females (34.67%).

Adult↗
PubMed2002

Diagnosis of typhoid fever by Dot enzyme immunoassay in an endemic region.

OBJECTIVE: To compare the results of Dot Enzyme Immunoassay (EIA) and concomitantly performed blood culture for the diagnosis of typhoid fever. METHODS: The results of Dot Enzyme Immunoassay (EIA) of patients who also had blood cultures/bone marrow culture performed at the same time were analyzed. The period of study spans between April 1997-September 1997. RESULTS: A total of 1760 Dot Enzyme Immunoassays were performed from April 1997 to September 1997. Of these, only 128 (7.2%) cases had concomitantly performed blood/bone marrow cultures. Therefore, the study was narrowed down to these 128 cases. Sixty-nine cases were culture positive for S. typhi. Of these culture proven cases, IgM antibodies by Dot EIA were positive only in 49 (71%) cases while 20 (28.9%) of culture proven cases remained negative for IgM antibodies. CONCLUSION: Taking blood/bone marrow culture as gold standard, the sensitivity of Dot EIA was found to be 71% while specificity was found to be 43%. The predictive value of the positive test was found to be 59.7% and that of a negative test was found to be 56.5%.

Endemic Diseases↗
PubMed2002

Universal hepatitis B vaccination of UK adolescents: a feasibility and acceptability study.

The feasibility of introducing universal hepatitis B immunisation was assessed by offering the vaccine to all 11-12 year old pupils in Greater Glasgow (approximately 10,800). Consent was received from 92% of the school roll, and 91.3%, 89.2% and 80.3% received at least 1, at least 2, and 3 doses respectively. The findings of this study constitute key evidence for the ongoing debate in the UK on hepatitis B vaccination.

Adolescent↗
PubMed2002

Potential of specialist drug services to deliver hepatitis B vaccination.

The city of Glasgow has a large population of injecting drug users (IDUs) who are likely to be susceptible to acute hepatitis B infection. We evaluated the effectiveness of a hepatitis B vaccination programme delivered at three existing types of services for IDUs. It was found that while uptake rates were generally low, they were higher at services where throughput of patients was lower, where clients had continuing relationships with services and where staff training and confidence were better.

Adult↗
PubMed2002

Single dose intravenous regional antibiotic in clean orthopaedic procedures.

Patients undergoing clean orthopaedic operations with tourniquet in Orthopaedic Department of a tertiary level hospital in Dhaka during August 1999 to March 2002 were consecutively enrolled in a prospective clinical study to explore the efficacy and safety of regional prophylaxis with single dose antibiotic. Eighty two patients with 83 operations received 750-mg cefuroxime in 40 & 20 ml of distilled water, into a dorsal vein of the foot or hand respectively to be operated on immediately after the tourniquet was inflated. Patients with bilateral operation, regional administration of cefuroxime were also repeated for the operation on the other extremity. Follow up ranged from 3 weeks to 2 years & 7 months. None of the patients experienced local or systemic adverse effects following regional administration of cefuroxime. Also none developed early infection (superficial or deep) during the follow-up period. Infective complications at distant sites like UTI were observed in one case with bilateral corrective osteotomy for knocked knee deformity. It was probably due to catheterization in the immediate post-operative period, which was rapidly cured following antibiotic treatment and removal of catheter. Regional administration of single dose antibiotic appears to be a safe and effective prophylaxis for the control of early infection in clean orthopaedic procedures. Late infection is blood borne and that can not be controlled by prophylactic use of antibiotic.

Adolescent↗
PubMed2002

Nutritional status and birth outcomes of the diabetic and non-diabetic pregnant women.

This cross sectional study compares the nutritional status and birth outcomes of 357 diabetic and non-diabetic pregnant women (203 DM and 154 NDM as control). Uncomplicated diabetic and non-diabetic pregnant women of singleton pregnancies with age range of 19-35 years were enrolled at term in BIRDEM hospital. Maternal anthropometry and neonatal anthropometric measurements were taken following standard techniques. Educational level was significantly different between the groups. The diabetic mothers were found significantly less educated (p<0.0001) compared to non-diabetic mothers. Highly significant differences were observed between the groups on mean maternal age, weight at term, height, body mass index (BMI), mid arm circumference (MAC), and hemoglobin concentration (p values for all: <0.001) with higher values for the DM group. Most of the DM pregnant mothers were either overweight (BMI: 26.0-29.0) or obese (BMI: >29.0), on the other hand most of the NDM pregnant mothers were within normal range (BMI: 19.8-26.0). DM pregnant mothers were found more anemic (45.8% vs. 23.4%; p<0.001). Mean birth weight of the infants of DM & NDM groups were 3100g +/- .500g and 2850g +/- 360g respectively. The mean chest circumference of the infants of DM mothers was found significantly higher for diabetic group (p<0.01). DM mothers delivered most of the preterm babies (16.3% vs. 5.8%; p<0.002) and macrosomy babies were found only in this group (5.9%). Significant correlation was observed between birth weight and maternal MAC (p<0.001) in both the groups. Head circumference was found significantly correlated with maternal MAC and age in the DM group only. Diabetic pregnant women were significantly different compared to the non-diabetic group by nutritional status. The DM group experienced more anemia and preterm deliveries and macrosomic babies were born only in them.

Adult↗
PubMed2002

Clinical profile of acute flaccid paralysis.

This study was done to determine the clinical course, cause and outcome of Acute Flaccid Paralysis (AFP) in children. All AFP cases (< 15 years) in the children's ward of Khulna Medical College Hospital (Bangladesh) were recorded, investigated and followed up to sixty days as a part of passive surveillance. Main outcome variables were vulnerable age group, vaccine status, predominant limb involvement, clinical variants, virus isolation and residual paralysis. Thirty-four children with AFP were admitted in hospital in the last three years with the highest number (14) in 1998. The majority of children belonged to the age group 5-9 years with a male female ratio of 1.3:1. Nearly one third of the cases were either partially vaccinated or not vaccinated at all. The lower limbs bore the brunt of paralysis excepting a few (14.7%). Clinically, Guillain Barre Syndrome was the commonest (47.1%) followed by encephalomyelitis. No poliovirus was isolated from these cases. Residual paralysis was observed in four out of ten cases who returned for follow up. AFP will continue to occur even after eradication of poliomyelitis and Guillain Barre Syndrome is the most important clinical entity for this.

Acute Disease↗
PubMed2001

C. elegans RAD-5/CLK-2 defines a new DNA damage checkpoint protein.

BACKGROUND: In response to genotoxic stress, cells activate checkpoint pathways that lead to a transient cell cycle arrest that allows for DNA repair or to apoptosis, which triggers the demise of genetically damaged cells. RESULTS: During positional cloning of the C. elegans rad-5 DNA damage checkpoint gene, we found, surprisingly, that rad-5(mn159) is allelic with clk-2(qm37), a mutant previously implicated in regulation of biological rhythms and life span. However, clk-2(qm37) is the only C. elegans clock mutant that is defective for the DNA damage checkpoint. We show that rad-5/clk-2 acts in a pathway that partially overlaps with the conserved C. elegans mrt-2/S. cerevisiae RAD17/S. pombe rad1(+) checkpoint pathway. In addition, rad-5/clk-2 also regulates the S phase replication checkpoint in C. elegans. Positional cloning reveals that the RAD-5/CLK-2 DNA damage checkpoint protein is homologous to S. cerevisiae Tel2p, an essential DNA binding protein that regulates telomere length in yeast. However, the partial loss-of-function C. elegans rad-5(mn159) and clk-2(qm37) checkpoint mutations have little effect on telomere length, and analysis of the partial loss-of-function of S. cerevisiae tel2-1 mutant failed to reveal typical DNA damage checkpoint defects. CONCLUSIONS: Using C. elegans genetics we define the novel DNA damage checkpoint protein RAD-5/CLK-2, which may play a role in oncogenesis. Given that Tel2p has been shown to bind to a variety of nucleic acid structures in vitro, we speculate that the RAD-5/CLK-2 checkpoint protein may act at sites of DNA damage, either as a sensor of DNA damage or to aid in the repair of damaged DNA.

Adenosine Triphosphatases↗
PubMed2001

Search for the familon via B(+/-) --> pi+/-X(0), B(+/-) --> K(+/-)X(0), and B(0) --> K(0)(S)X(0) decays.

We have searched for the two-body decay of the B meson to a light pseudoscalar meson h = pi(+/-),K+/-,K(0)(S) and a massless neutral feebly interacting particle X(0) such as the familon, the Nambu-Goldstone boson associated with a spontaneously broken global family symmetry. We find no significant signal by analyzing a data sample containing 9.7x10(6) BBbar mesons collected with the CLEO detector at the Cornell Electron Storage Ring, and set 90% C.L. upper limits italicB(B(+/-) --> h(+/-)X(0)) = 4.9x10(-5) and italicB(B(0) --> K(0)(S)X(0)) = 5.3x10(-5). These limits correspond to a lower bound of approximately 10(8) GeV on the family symmetry breaking scale with vector coupling involving the third generation of quarks.

Journal Article↗
PubMed2001

Determination and use of a transition state for the enzyme estrone sulfatase (ES) from a proposed reaction mechanism.

Using the postulated mechanism for the enzyme estrone sulfatase (ES), we have determined a possible transition state for the reaction catalysed by ES as a representation of the active site. Using the derived structure, we have undertaken the molecular modelling of several steroidal and non-steroidal inhibitors in an attempt to rationalise the inhibitory activity of a number of potent inhibitors.

Catalytic Domain↗