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Biomedical subjects

N Ahmed

Publications and source records attributed to N Ahmed.

At least 145 records · Page 8Linked to original sources
PubMed1994

Management of tuberculosis by practitioners of Peshawar.

In this report the drug prescribing practices of practitioners are described. The results indicate that a high proportion (80%) of practitioners still prescribe long duration chemotherapy. The most frequently prescribed drugs are rifampicin (87%), isoniazid (89%) and streptomycin (73%). Despite the use of these highly effective drugs the duration of illness after diagnosis in 31% is over three years. The possible reasons for the poor control of the disease are noncompliance with treatment and multidrug resistance of mycobacterium tuberculosis. The prescribing practices of the practitioners indicate that they are not receiving continuing education and training on the case management of TB.

Child↗
PubMed1993

Diffusing capacity decreases after heart transplantation.

We evaluated the following spirometric values: forced vital capacity (FVC), first second expiratory volume (FEV1), FEV1/FVC, the lung volumes, total lung capacity (TLC), residual volume (RV), and single breath diffusing capacity for CO in 22 patients, before and after heart transplant. We found abnormal pulmonary function in 21 patients before heart transplantation. Despite postoperative increases in lung volumes in 10 patients, abnormal pulmonary function persisted in 20 patients after heart transplant. Mean values for lung volumes and flow rates did not change but diffusion for CO decreased significantly after heart transplantation. Diffusion failed to correlate with ejection fraction, pulmonary arterial pressure, pulmonary capillary wedge pressure (PCWP), and pulmonary vascular resistance; however, in a subset of patients with improved postoperative lung volumes, preoperative diffusion for CO correlated with preoperative PCWP. We conclude that pulmonary function abnormalities are common among heart transplant recipients. Diffusion abnormalities are not linearly related to indices of cardiac function measured before transplantation and diffusion abnormalities appear to be multifactorial in cause. The posttransplant decrease in diffusion appears to result from the combined effects of decreased postoperative lung volumes in some patients and relief of heart failure induced pulmonary vascular engorgement in others. Improvement in lung volumes and flow rates may occur but cannot be expected after heart transplantation, and diffusion decreases after heart transplantation. The fact that pulmonary function and lung volumes do not improve following heart transplantation implies to underlying lung disease or permanent lung alterations result from chronic heart failure.

Adult↗
PubMed1993

Comparative study of staphylococcal co-agglutination and latex agglutination for detection of enterotoxigenic Escherichia coli.

Several biological and immunological methods have been used for detection of ETEC. In this work a comparative study was done between staph-co-agglutination and latex agglutination. From the 75 faecal samples collected from infants and children having acute diarrhea, the total number of E. Coli strains isolated were 64. Out of these 64 strains, 6 strains were found to be positive for Labile Toxin (LT) production by both latex agglutination and staphylococcal co-agglutination test. However, another 3 strains which were negative by latex agglutination were found to be positive by staph co-agglutination test. The latex agglutination test was found to be simple, easy and rapid. However this test was less sensitive in detection of ETEC. The staph-co-agglutination was also found to be simple, easy but it takes longer time (14 days). It was concluded that both tests are simple, inexpensive to perform and can be used for rapid detection of ETEC.

Agglutination Tests↗
PubMed1993

Glycolytic, glutaminolytic and pentose-phosphate pathways in promyelocytic HL60 and DMSO-differentiated HL60 cells.

The human leukaemic cell line HL60 undergoes differentiation to granulocyte-like cells in response to dimethylsulphoxide (DMSO). The rates of glucose and glutamine utilization were studied in HL60 cells that were either undifferentiated or fully differentiated by 9 days exposure to DMSO. Differentiation did not alter the rate of utilization of exogenous glucose, approximately 75% of which was converted to lactate in each case. The activities of hexokinase, phosphofructokinase, pyruvate kinase and citrate synthase were similarly unaffected. In contrast, the activity of the oxidative segment of the pentose-phosphate pathway was enhanced by differentiation, and no glycogen synthase activity could be detected. These observations are consistent with the significantly lower content of glycogen, the increased activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase and the increased oxidation of [1-14C] glucose relative to [6-14C] glucose in the differentiated cells. Glucose utilization was depressed by exogenous glutamine but, at the same time, glutamine utilization was enhanced by glucose in both cell types; these reciprocal effects were more pronounced in the undifferentiated HL60 cells. Glucose utilization may be depressed in the presence of glutamine as a result of the allosteric inhibition of a rate-limiting step of glycolysis (eg. phosphofructokinase). In spite of having glutaminase activity twice that of their differentiated counterparts, the uptake of glutamine by undifferentiated HL60 cells was low, especially when it was the sole substrate. The stimulation of glutaminolysis by glucose may be due to activation of mitochondrial glutamine transport. A large proportion of the glutamine utilized by both cells contributed to a net accumulation of glutamate, aspartate and alanine, whilst up to 35% was oxidized to CO2. In contrast, almost all of the glucose utilized was converted to lactate and very little was oxidized. The high rates of glycolysis and glutaminolysis observed before and after differentiation may not contribute primarily to energy production but may supply, in undifferentiated cells, substrates for biosynthetic processes that generate nucleic acid precursors or, in the case of differentiated cells which synthesize reactive oxygen intermediates, substrates that maintain NADP in a reduced state.

Cell Differentiation↗
PubMed1993

Computerized task battery assessment of cognitive and performance effects of acute phenytoin motion sickness therapy.

Phenytoin was previously evaluated as an efficacious anti-motion sickness therapy in more than 24 individuals. To be effective, this short-term, novel therapy requires serum levels in the anticonvulsant range; therefore, it became imperative that the effects of phenytoin upon cognition and performance be quantified. Each subject was tested on a performance battery (Criterion Task Set) on two occasions while on either phenytoin treatment or placebo for subsequent statistical comparison. We evaluated 23 subjects with phenytoin serum levels ranging from 8.9 to 23.9 micrograms/L. While subjects with the higher serum levels consistently reported subjective side effects, there was no statistically significant degradation of sensory, cognitive, or performance capabilities compared to placebo.

Adult↗
PubMed1992

Structure-activity study and design of multidrug-resistant reversal compounds by a computer automated structure evaluation methodology.

We have studied the relation between the structure and the multidrug resistance-reversal activity of a set of diverse chemicals with the MULTICASE structure-activity program. A number of key structural features were identified as being related to multidrug resistance reversal activity. Using these key features, we identified seven new compounds predicted to have substantial activity. These were obtained and tested experimentally on a CHO/CHRC5 cell line derived from the AB1 Chinese hamster ovary line in the presence of vincristine and vinblastine. Of the seven compounds tested so far, four showed substantial reversal activity, the most potent of them exhibiting activity at par with verapamil.

Animals↗
PubMed1992

Ageing of the human corneal stroma: structural and biochemical changes.

High and low angle X-ray diffraction patterns from the corneal stroma give information about the mean intermolecular spacing of the collagen molecules and the mean interfibrillar spacing of the collagen fibrils, respectively. X-ray data were collected, using a high intensity synchrotron source, from human corneas and sclera at approximately physiological hydration. The spacings were measured as a function of tissue age. Between birth and 90 years there is an increase in the cross-sectional area associated with each molecule in corneal collagen from approx. 3.04 nm2 to 3.46 nm2, and an increase in scleral collagen from approx. 2.65 nm2 to 3.19 nm2. These changes may be due to an increase in the extent of non-enzymic cross-linking between collagen molecules over the age range. We have investigated this possibility by measuring collagen glycation using the thiobarbituric acid assay and the subsequent advanced glycation end-products (AGEs) using fluorescence emission. The results obtained have shown an age-related increase in glycation and AGEs in both tissues. We have also demonstrated a decrease in the interfibrillar spacing of corneal collagen with increasing age which may be related to changes in the proteoglycan composition of the interfibrillar matrix.

Adolescent↗
PubMed1992

Failure of common glycation assays to detect glycation by fructose.

Serum albumin was modified by in vitro glycation with either fructose or glucose, to see whether the common clinical assays for glycation were able to detect both fructose- and glucose-induced changes in protein structure in diabetes. Although fluorescence measurements showed that fructose causes far more protein damage than glucose, neither serum fructosamine (SFA) nor phenylboronate affinity (PBA) glycation assays reflected these changes. The SFA method implied that fructose causes only about 5% of the glycation induced by glucose; with PBA the proportion was 25%. The thiobarbituric acid- and periodate-based assays also greatly underestimated the true extent of fructation. We discuss these discrepancies with respect to the underlying chemistry, emphasizing the difference between aldehydic and ketonic Amadori products (exemplified by fructose and glucose derivatives, respectively). The implications for detecting fructose-induced secondary diabetic complications are also discussed.

Colorimetry↗
PubMed1992

Trypsin inhibitors of buffalo seminal plasma.

Two trypsin inhibitors from acid-treated buffalo seminal plasma were purified by gel filtration and affinity chromatography. These acid-stable trypsin inhibitors having charge heterogeneity were homogeneous with respect to size as revealed by gel filtration and SDS-PAGE. Gel filtration data suggest molecular weight value of 9,900 Da for inhibitor I and 10,900 Da for inhibitor II. Molecular weight estimated by SDS-PAGE was found to be 10,600 Da and 11,200 Da for inhibitors I and II, respectively. The hydrodynamic properties such as Stokes radii (1.58 nm and 1.62 nm); intrinsic viscosity (2.5725 ml/g and 2.5025 ml/g) and diffusion coefficient (13.499 x 10(-11) m2/sec. and 13.166X10(-11) m2/sec) respectively for inhibitor I and II were determined by analytical gel filtration. These inhibitors were fairly thermostable and could not be stained by PAS reagent. Both the inhibitors were found to inhibit buffalo acrosin but not bovine chymotrypsin.

Animals↗
PubMed1991

A microassay for protein glycation based on the periodate method.

The periodate assay for glycated protein has been adapted for use with a microplate reader. Up to 94 samples can be read in 40 s, and sensitivity has been improved so that only 2-40 nmol of protein-bound sugar are needed per well. Yields have been increased to over 90%, allowing in vitro glycation of human serum albumin to be assayed on 0.1-mg aliquots.

Glycoproteins↗
PubMed1991

Anaphylactic reaction because of intrauterine 32% dextran-70 instillation.

Anaphylactic reaction associated with hysteroscopy using 32% dextran-70 as a distending medium is a rare phenomenon. We report anaphylactic reaction associated with hysteroscopy using dextran that was delivered manually in three otherwise healthy women occurring within a 6-month period. The rapidity and pressure of dextran administered might facilitate intravascular absorption and predispose patients to this phenomenon.

Adult↗
PubMed1991

The human promyelocytic HL60 cell line: a model of myeloid cell differentiation using dimethylsulphoxide, phorbol ester and butyrate.

The release of the reactive oxygen species that accompanies the oxidative burst was studied in HL60 cells differentiated with either dimethylsulphoxide, butyrate or phorbol myristate acetate in order to establish the extent to which differentiated cells are phenotypically similar to human neutrophils, monocytes and macrophages. When phorbol myristate acetate was used as a stimulus, the rates of superoxide production by dimethylsulphoxide and butyrate differentiated HL60 cells was not significantly different from those observed in neutrophils and monocytes isolated from normal peripheral blood. Similar results were obtained when luminol-dependent chemiluminescence was measured in the presence of horseradish peroxidase using phorbol myristate acetate as the stimulus. However, in the absence of horseradish peroxidase, the luminol-dependent chemiluminescence in the dimethylsulphoxide and butyrate-differentiated HL60 cells was significantly lower than that of the control cells isolated from human blood, reflecting the absence of myeloperoxidase in the differentiated cells. In contrast, HL60 cells differentiated by phorbol myristate acetate failed to show any increased generation of superoxide or luminol-dependent chemiluminescence upon stimulation. Impaired release of lysosomal enzymes by the chemically differentiated cells suggests impairments in the extent of differentiation resulting in cells with defective azurophilic degranulation processes. It is concluded that HL60 cells differentiated by the above agents are somewhat controversial models of promyelocyte differentiation into typical neutrophilic, monocytic and macrophage-like cells.

Butyrates↗
PubMed1991

Prevalence of Campylobacter pylori in non-ulcerative dyspepsia.

Endoscopic biopsies were taken from the gastric antral mucosa, in 150 cases of non-ulcerative dyspepsia at the Gastroscopic Clinic, Dist. Hospital, Belgaum. Spiral or curved bacilli, were demonstrated in specimens from 99 patients. The histologic demonstration of the organism by Warthin Starry stain (66%) was superior to Haematoxylin and Eosin (47.33%), Urease test (42%) and Gram's stain (35.33%). There was a strong association between C pyloridis in the gastric mucosa and histologically defined gastritis (95.55%).

Adult↗