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Biomedical subjects

S Chowdhury

Publications and source records attributed to S Chowdhury.

At least 55 records · Page 3Linked to original sources
PubMed1998

Hypoglycemia-associated hyperammonemia caused by impaired expression of ornithine cycle enzyme genes in C/EBPalpha knockout mice.

Ammonia produced by amino acid metabolism is detoxified through conversion into urea by the ornithine cycle in the liver, whereas carbon skeletons of amino acids are converted to glucose by gluconeogenic enzymes. Promoter and enhancer sequences of several genes for ornithine cycle enzymes interact with members of the CCAAT/enhancer-binding protein (C/EBP) transcription factor family. Disruption of the C/EBPalpha gene in mice causes hypoglycemia associated with the impaired expression of gluconeogenic enzymes. Here we examined the expression of ornithine cycle enzyme genes in the livers of C/EBPalpha-deficient mice. mRNA levels for the first, third, fourth, and fifth enzymes of five enzymes in the cycle were decreased in C/EBPalpha-deficient mice. Protein levels for the first, second, fourth, and fifth enzymes were also decreased. In situ hybridization analysis revealed that the enzyme mRNAs were distributed normally in the periportal region but were disordered in C/EBPalpha-deficient mice with relatively higher mRNA levels in the midlobular region. Blood ammonia concentrations in the mutant mice were severalfold higher than in wild-type mice. Thus, C/EBPalpha is crucial for ammonia detoxification by ornithine cycle enzymes and for coordination of gluconeogenesis and urea synthesis.

Ammonia↗
PubMed1998

Radiolabelled mixed leukocytes and pure granulocytes with stabilized 99Tcm-exametazime.

Although the methylene blue stabilizer extends the shelf life of 99Tcm-exametazime to 4-6 h after reconstitution, the dark blue appearance of the mixture of stabilized 99Tcm-exametazime and blood components makes it impossible to separate out the leukocyte button. The aim of this study was to assess the feasibility of using stabilized 99Tcm-exametazime to radiolabel mixed leukocytes separated by Volex sedimentation with hypotonic lysis (VL) and pure granulocytes isolated by a single-density Ficoll-Hypaque gradient with hypotonic lysis (FL). Isolated cells from 40-ml and 80-ml donor blood samples were mixed with 0.5 ml stabilized 99Tcm-exametazime (approximately 925 MBq 99Tcm and 62.5 micrograms exametazime) and incubated at room temperature for 15 min. After incubation, two dilution steps with 3 ml and 9 ml of 12.6% ACD/NS (anticoagulant citrate dextrose, solution A, USP, mixed with 0.9% NaCl, v/v) were conducted to dilute the dark blue mixture and to remove any unbound 99Tcm activity. With the addition of 9 ml of 12.6% ACD/NS solution to the 1-ml bottom portion from the first dilution, the supernatant of the centrifuged preparation was clear enough to be withdrawn. The overall labelling efficiency (LE) of labelled leukocytes and granulocytes was 87.1 +/- 4.9% and 87.7 +/- 6.2%, respectively (n = 12 each). Overall, radiolabelled cells (n = 12) from the 80-ml blood samples (LE = 90.3 +/- 2.8%) had an approximately 6% higher labelling efficiency than from the 40-ml blood samples (LE = 84.5 +/- 6.0%) and also had a slightly better in vitro stability compared to the 40-ml samples. The in vitro stability studies showed that only approximately 2% (n = 48) 99Tcm activity was eluted each hour from the radiolabelled leukocytes or granulocytes for the 40-ml or 80-ml blood samples during the 6-h evaluation period. Cell viability of all labelled leukocyte samples was confirmed by the trypan blue staining technique. In conclusion, mixed leukocytes separated by the VL method and pure granulocytes isolated by the FL method can be effectively labelled with stabilized 99Tcm-exametazime with the use of the 'double dilution' technique.

Cell Survival↗
PubMed1998

Primary term ovarian pregnancy superimposed by intrauterine pregnancy: a case report.

A case of primary ovarian pregnancy proceeding upto term superimposed by another intrauterine pregnancy is presented. Compound extrauterine and intrauterine pregnancy is a rare obstetric phenomenon and still rarer is a primary ovarian pregnancy proceeding upto the term. The condition was diagnosed at laparotomy during the second trimester of current pregnancy. Diagnostic laparotomy was done because the ovarian pregnancy was mimicking an ovarian tumur. The ovarian pregnancy was successfully managed by surgery. Normal vaginal delivery of a term intrauterine pregnancy occurred in due time. The difficulty of diagnosing the heterotopic pregnancy is discussed and the clinico-pathological features of primary term ovarian pregnancy is emphasized, as it is a very rare condition.

Adult↗
PubMed1998

Knowledge discovery and case based reasoning in health promotion: development of a help-desk for prevention of occupational injuries.

This paper presents the concepts, ideas and techniques behind Case Based Reasoning (CBR) in relation to knowledge extraction techniques for health promotion. The ultimate goal is to develop a help-desk service for advice about preventive measures to be taken concerning concrete occupational injury hazards. CBR has been suggested to be a complimentary method to knowledge extraction in order to take direct advantages of large databases for building decision support systems. In this work a database on work injuries is being used to develop a CBR application using a CBR shell-called Recall.

Accidents, Occupational↗
PubMed1998

Use of stabilized technetium-99m-exametazime for radiolabeling leukocytes.

UNLABELLED: With a stabilizing agent (i.e., methylene blue and sodium phosphate buffer mixture), the in vitro stability of 99mTc-exametazime has been increased to 4-6 hr postreconstitution. However, it is not feasible to use the stabilized 99mTc-exametazime for leukocyte radiolabeling. This is due to the deep blue appearance of the mixture of stabilized 99mTc-exametazime and blood components, which makes it impossible to separate properly the supernatant from the leukocyte button. In our study, we have developed a practical methodology for overcoming this difficulty in order to use stabilized 99mTc-exametazime in leukocyte labeling. METHODS: The stabilized 99mTc-exametazime preparation used in our method consisted of 2 ml 7.4-8.0 GBq (200-215 mCi) 99mTc and 2 ml methylene blue/phosphate buffer solution. The separated leukocytes from 80-ml fresh venous blood were incubated with three different ages (i.e., 0-, 4-, or 6-hr postreconstitution) of stabilized 99mTc-exametazime (approximately 925 MBq, approximately 25 mCi; 0.5-1 ml) at room temperature for 15 min. After incubation, 3 ml of 12.6% ACD/NS solution (anticoagulant citrate dextrose, solution A, USP mixed with 0.9% NaCl, v/v) was added to the tube and centrifuged at 160 g for 5 min. Three milliliters of the dark blue supernatant were carefully removed, and the bottom 1 ml portion was resuspended with 9 ml of 12.6% ACD/NS solution. After centrifugation (160 g for 5 min), the supernatant was clear enough to be drawn off without disturbing the radiolabeled leukocyte button. The white cell button was then resuspended in 4 ml of platelet-poor plasma. RESULTS: The overall labeling efficiency (LE) of our new technique was 67.8%-91.9%, with the higher LE associated with fresher stabilized 99mTc-exametazime. During a 6-hr in vitro stability evaluation, radiolabeled leukocytes lost 1.2% +/- 0.3% (n = 24), 1.3% +/- 0.1% (n = 16) and 1.8% +/- 0.1% (n = 16) each hour of the cell-bound 0-, 4-, and 6-hr-old 99mTc-exametazime, respectively. The 99mTc-exametazime-labeled leukocytes examined by the trypan blue staining technique at 6-hr postradiolabeling yielded nonstained cells indicating viable leukocytes. CONCLUSION: We concluded that with a small volume of 99mTc-exametazime and double dilution steps with 12.6% ACD/NS solution, stabilized 99mTc-exametazime can be used effectively for leukocyte radiolabeling with a high LE and long in vitro stability.

Drug Stability↗
PubMed1998

Effect of Norplant on liver function.

Combined pills have known adverse effects on liver function. Progesterone based contraceptives are thought to be safer in this regard. The effect of Norplant, a levonorgestrel contraceptive implant, on liver function was evaluated in 149 Bangladeshi women of reproductive age in this study. Liver function tests and ultrasonography of hepato-biliary system were done before and after the implantation. The patients were followed upto two years. There were non-significant transient rise of serum bilirubin and slight enlargement of liver during the first year. There was no significant change in the levels of AST, ALT, alkaline phosphatase, total protein, albumin-globulin ratio and prothrombin time. The results suggest that Norplant has no adverse effect on liver function.

Adolescent↗
PubMed1998

"EXPATH" an expert system for pathology for the diagnosis of jaundice.

Computers are increasingly playing an important role in the field of medicine. A computer aided expert system has been developed for the differential diagnosis of jaundice. In this article the major features and application of this modular software are discussed.

Diagnosis, Computer-Assisted↗
PubMed1997

Comparison of results of various methods used to determine the extent of modification of methoxy polyethylene glycol 5000-modified bovine cupri-zinc superoxide dismutase.

The protein bovine cupri-zinc superoxide dismutase (SOD) was modified by the reaction of lysine residues with an active ester of methoxy polyethylene glycol 5000 (PEG). The extent of modification was determined by capillary zone electrophoresis, matrix-assisted laser desorption/ionization mass spectrometry, Fourier-transform infrared spectroscopy, and Raman spectroscopy and after removing PEG by alkaline hydrolysis of the linkages to SOD followed by quantification of the released PEG using gel-permeation chromatography. There was generally good agreement among the results obtained by these techniques on a typical sample of the PEG-modified protein. The results, extent of protein modification, determined by the preceding methods were compared to that found from the classical trinitrobenzene sulfonic acid (TNBS) procedure. In addition to providing alternatives to the TNBS procedure, results from the described methodologies strongly suggest that the extent of modification determined from the TNBS procedure is overestimated.

Animals↗
PubMed1997

Control of tuberculosis by community health workers in Bangladesh.

BACKGROUND: Tuberculosis remains a major public-health problem in Bangladesh, despite national efforts to improve case identification and treatment compliance. In 1984, BRAC (formerly the Bangladesh Rural Advancement Committee), a national, non-governmental organisation, began an experimental tuberculosis-control programme in one thana (subdistrict). Community health workers screened villagers for chronic cough and collected sputum samples for acid-fast bacillus (AFB) microscopy (phase one). Positive patients received 12 months of directly observed therapy. Phase two (1992-94) included another nine thanas and, in phase three (1995), eight more thanas were included. From 1995, the treatment was an 8-month oral regimen. METHODS: In 1995-96, we analysed all programme data from 1992 to 1995. First we analysed phases two (12-month therapy) and three (8-month therapy) separately for proportion cured, died, treatment, failed, defaulted, migrated, and referred. Second, we did a cross-sectional survey of tuberculosis cases in more than 9000 randomly selected households in two phase-two thanas and one non-programme thana, and analysed the follow-up of all patients treated in the programme thanas. FINDINGS: In the phase-two analysis, 3497 (90%) of 3886 cases identified had accepted 12-month treatment. In phase three, all of 1741 identified cases accepted the 8-month regimen. 2833 (81.0%) and 1496 (85.9%) in phases two and three, respectively, were cured; 336 (9.6%) and 133 (7.6%) died. The relapse rate 2 or more years after treatment was discontinued was higher than the early relapse rate. The drop-out rate was 3.1%. In the cross-sectional survey, the prevalence of tuberculosis in the two programme thanas was half of that in the comparison thana, where only government services were available (0.07 vs 0.15 per 100 [corrected]). INTERPRETATION: The BRAC tuberculosis-control programme has successfully achieved high rates of case detection and treatment compliance, with a cure rate of at least 85% and a drop-out rate of 3.1%. The prevalence survey suggested that at least half of all existing cases had been detected by the programme.

Adolescent↗
PubMed1997

The glucocorticoid-responsive gene cascade. Activation of the rat arginase gene through induction of C/EBPbeta.

The gene for liver-type arginase, an ornithine cycle enzyme, is induced by glucocorticoids in a delayed secondary manner. An enhancer element located around intron 7 of the rat arginase gene shows delayed glucocorticoid responsiveness, and it harbors two sites binding with members of the CCAAT/enhancer binding protein (C/EBP) family. Here, we investigate the role of these C/EBP binding sites in glucocorticoid response of the arginase gene. When inserted in front of the herpes simplex virus thymidine kinase promoter, these C/EBP sites exhibited glucocorticoid responsiveness in reporter transfection assay using rat hepatoma H4IIE cells. In footprint analysis using nuclear extracts of H4IIE cells, profiles of the protected areas of the two C/EBP sites changed when cells were treated with dexamethasone. In gel shift analysis, the complex formation for the two C/EBP sites was augmented in response to dexamethasone. Antibody supershift/inhibition analysis demonstrated that a major portion of the binding proteins induced by dexamethasone is C/EBPbeta. Induction of arginase mRNA by dexamethasone was preceded by augmentation of the C/EBP site-binding activities, which followed increase in C/EBPbeta mRNA. These results were consistent with the notion that the glucocorticoid response of the arginase gene is mediated by C/EBPbeta.

Animals↗
PubMed1997

Rapid preparation method for technetium-99m bicisate.

The method currently recommended for the preparation of technetium-99m bicisate (99mTc-bicisate) requires a lengthy 30-min incubation at room temperature. The purpose of this study was to evaluate an alternative method to shorten the preparation time. 99mTc-bicisate was prepared with 3.7 GBq (100 mCi) 99mTc according to the manufacturer's instructions, except for the final incubation step, which was replaced with the microwave heating procedure. A standard thin-layer chromatography (TLC) method (i.e., Baker-Flex silica gel IB-F TLC plate with ethyl acetate as mobile phase) was used for the determination of the radiochemical purity (RCP) of 99mTc-bicisate. Our evaluation with different microwave heating processes (300 W with different heating times) demonstrated that as the microwave heating temperature was increased (i.e., 44 masculine-71 masculine C), an increased percentage of samples reached 95% within 5 min post preparation (n=58). The highest RCP value (i.e., 97.4%+/-0.5%, n=10) could be obtained immediately after an 8-s microwave heating time at 300 W (microwave temperature at 69 masculine C), and an average RCP value of 96.4%+/-1.3% (n=90) was maintained throughout the 24-h evaluation period. However, the trend seemed to reverse at higher microwave temperatures (i.e., 76 masculine-90 masculine C), which reconfirmed our initial findings that overheating had no benefit for the preparation of 99mTc-bicisate. To ensure that temperature was the only determining factor, a hot water incubator set at 69 masculine C was used (n=6). Similar RCP results were achieved. In conclusion, the use of a microwave oven at a low heat cycle provides a rapid and efficient way to prepare 99mTc-bicisate.

Chromatography, Thin Layer↗
PubMed1997

Dynamics of conjunctival impression cytologic changes after vitamin A supplementation.

To investigate the chronological changes in conjunctival epithelium after supplementation with a massive oral dose of vitamin A, conjunctival impression cytology (CIC) with transfer was carried out repeatedly among 200 children aged 6-120 months in a randomized, double-blind, placebo-controlled study in Chandigarh (India). Significant conversion to normal CIC started 71-80 d after vitamin A supplementation and by 101-110 d conversion had taken place in all children. Compared with the placebo group, plasma retinol concentration at 100 d post-supplement was found to be significantly higher in the vitamin A-supplemented group P = 0.04. This study demonstrates that CIC responds to a massive oral dose of vitamin A 3-4 months after supplementation. These findings should guide future studies and evaluations in which CIC is used to assess response to vitamin A interventions.

Administration, Oral↗
PubMed1997

Specific detection of shedding and latency of bovine herpesvirus 1 and 5 using a nested polymerase chain reaction.

A sensitive method for simultaneously detecting and discriminating between bovine herpesviruses types 1 and 5 (BHV-1 and BHV-5) was developed using a nested polymerase chain reaction (PCR) technique. Following amplification using type-common primers derived from gC sequences, amplification using type-specific nesting primers produced different-sized bands specific to the corresponding types, as demonstrated by blot hybridization. Less than 0.1 plaque-forming units (PFU) of each virus and 75 fg or less of viral DNA were routinely detected. The PCR technique amplified correct product from 4 BHV-5 isolates and from 48 BHV-1 isolates, all from the United States, and did not amplify heterologous herpesviruses. The PCR technique was more sensitive than virus isolation in detection of BHV-1 or BHV-5 in nasal secretions from experimentally and naturally infected calves, and it detected BHV-1 or BHV-5 in trigeminal ganglia from these calves.

Alphaherpesvirinae↗
PubMed1997

Scatter factor stimulates tumor growth and tumor angiogenesis in human breast cancers in the mammary fat pads of nude mice.

Scatter factor (SF) (also known as hepatocyte growth factor) is a plasminogen-related growth factor that induces tumor cell motility, invasion, and angiogenesis. Its receptor is a tyrosine kinase encoded by c-met, a protooncogene. Human breast cancer cells express SF and c-met in vivo; but human breast cancer cell lines do not produce SF in vitro. To determine whether SF can modulate the in vivo growth of human breast cancers within a natural mammary environment, we studied the orthotopic growth of SF-transfected (SF+) versus control (SF-) clones of MDAMB231 human mammary carcinoma cells in the mammary fat pads of athymic nude mice. SF+ clones expressed SF mRNA and produced very high titers of SF protein, whereas SF- clones did not express SF mRNA or produce detectable SF protein. Two SF+ clones (21 and 29) showed significantly increased tumor growth rates, reaching 3- to 4-fold larger primary tumor volumes and weights by time of killing (p < 0.001), as well as higher rates of axillary lymph node metastasis (p < 0.02), as compared with two SF- clones (32 and 34). In contrast, in vitro proliferation rates, two-dimensional colony formation, and soft agar colony formation were no greater in SF+ than in SF- clones. We performed further studies to investigate the discrepancy between the in vivo and in vitro growth results. Tumor extracts from SF+ clone (21 + 29) tumors had 50-fold higher SF content than did SF- clone (32 + 34) tumors, confirming high-level SF expression in vivo in SF+ tumors. Immunostaining of tumor sections for proliferating cell nuclear antigen revealed only a modest increase in the proportion of cycling cells in SF+ versus SF- tumors (70% versus 60%, respectively). The terminal deoxytransferase-labeling index was equally low (approximately 1%) in SF+ and SF- tumors, suggesting that apoptosis was not responsible for the slower growth of SF- tumors. However, SF+ tumors had significantly higher tumor microvessel densities than SF- tumors (p < 0.001). Moreover, there were much higher titers of chemotactic activity for microvascular endothelial cells in cell-conditioned media and primary tumor extracts from SF+ clones as compared with SF- clones. As demonstrated using the rat cornea assay, there was more angiogenic activity in SF+ tumor extracts than in SF- extracts. The increased chemotactic and angiogenic activities in SF+ tumor extracts were not explained by secondary alterations in the content of the angiogenic mediator, vascular endothelial growth factor, or the antiangiogenic glycoprotein, thrombospondin-1; and those activities were neutralized using an anti-SF monoclonal antibody. These findings suggest that SF promotes the orthotopic growth of human breast cancers, at least in part, by stimulating tumor angiogenesis.

Adipose Tissue↗