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M Das

Publications and source records attributed to M Das.

At least 37 records · Page 2Linked to original sources
PubMed2002

Selective expansion of fibroblast subpopulations from pulmonary artery adventitia in response to hypoxia.

Proliferation of fibroblasts contributes to the adventitial thickening observed during the development of hypoxia-induced pulmonary hypertension. However, whether all or only specific subpopulations of fibroblasts proliferate during this process is unknown. Because lung, skin, and gingiva contain multiple fibroblast subpopulations, we hypothesized that the pulmonary artery (PA) adventitia of neonatal calves is composed of multiple fibroblast subpopulations and that only selective subpopulations expand under chronic hypoxic conditions. Fibroblast subpopulations were isolated from PA adventitia of control calves using limited dilution cloning techniques. These subpopulations exhibited marked differences in morphology, actin expression, and serum-stimulated growth. Only select fibroblast subpopulations demonstrated the ability to proliferate in response to hypoxia. Fibroblast subpopulations were similarly isolated from calves exposed to hypoxia (14 days). With regard to morphology, actin expression, and serum-stimulated growth of subpopulations, there were no obvious differences in fibroblast subpopulations between the hypoxic and the control calves. However, the number of fibroblast subpopulations with about a twofold increase in hypoxia-induced DNA synthesis was significantly greater in the hypoxic calves (26%) compared with control calves (10%). We conclude that the bovine PA adventitia comprises numerous phenotypically and biochemically distinct fibroblast subpopulations and that select subpopulations expand in response to chronic hypoxia.

Animals↗
PubMed2002

Effects of 10 mg and 15 mg oral procyclidine on critical flicker fusion threshold and cardiac functioning in healthy human subjects.

The critical flicker fusion threshold (CFFT) is thought to index alertness and cortical arousal. Sedative drugs reduce CFFT while psychostimulants increase it. Procyclidine is an anticholinergic that is used to control the extrapyramidal side-effects of antipsychotics in schizophrenia. This study examined the effects of clinically relevant doses of oral procyclidine administration on CFFT and heart rate in two separate experiments (Experiment 1, drug dose: 10 mg, n = 16; Experiment 2, drug dose: 15 mg, n = 12) involving healthy subjects using a double-blind, placebo-controlled, cross-over design. 10 mg procyclidine had no significant effect on CFFT, heart rate or self-ratings of mood, but the 15 mg dose significantly lowered CFFT at 1 h and 2 h after procyclidine administration, increased drowsiness ratings and produced a drop in heart rate. The effects observed in this study may have implications for treatment compliance of schizophrenic patients, choice of antipsychotics, prescribing to patients with heart disease and monitoring of cardiac function under treatment. Further investigations are required to quantify the effects of procyclidine on CFFT and cardiac function in patients with schizophrenia.

Adult↗
PubMed2002

Discriminatory value of blood urea:creatinine ratio in upper gastrointestinal bleeding with and without cirrhosis of liver.

AIM: To evaluate the discriminatory ability of blood urea:creatinine ratio in upper gastro-intestinal bleeding (UGIB) with and without cirrhosis of liver. METHODS: Blood urea:creatinine (BU/CR) ratio in 160 adult patients of UGIB were studied after excluding clinically overt cirrhosis of liver, renal failure and hematochezia. All were subjected to ultrasonography of abdomen. Only those showing cirrhosis and portal hypertension (n=76) were taken up for liver biopsy to confirm the diagnosis. BU/CR ratio was compared to UGIB cases without cirrhosis of liver (n=84). RESULTS: The mean (+/- SD) blood urea creatinine ratio was significantly lower in the group with cirrhosis than without cirrhosis of liver (22.49 +/- 6.13 vs. 38.07 +/- 8.08, Z value 13.91). CONCLUSION: In absence of renal failure, the blood urea/creatinine ratio may differentiate UGIB with associated cirrhosis of liver from those without. Being simple, cheap and readily available, it can be of some value in those patients with cirrhosis of liver clinically not associated with gross findings of cirrhosis. In our study it was also noted that, an arbitrary cut-off value of 30 showed considerable overlap between the two groups; hence this ratio may not always differentiate between the cirrhotics and non-cirrhotics. Therefore, reproducibility of these results needs further studies, taking into account other factors which can modify the BU level in our population.

Adult↗
PubMed2002

Antineoplastic effect of new boron compounds against leukemic cell lines and cells from leukemic patients.

Three new boron compounds, dihydroxy (oxybiguanido) boron (iii) hydrochloride monohydrate (HB), guanidine biboric acid adduct (GB) and hydroxosalicyl hydroxomato boron (iii) (SHB) were studied to observe their antineoplastic effect, if any. Leukemic cells isolated from acute lymphatic leukaemia (ALL) patients and chronic myeloid leukaemia patients (CML) and myeloid leukemia cell lines (HL 60 and U-937) showed cell growth inhibition after treatment with the boron compounds. MTT assay showed that the growth of metabolically active cells was inhibited by treatment with these drugs. The molecular mechanism by which SHB induced apoptosis in immature blast cells was also investigated by ladder formation in gel electrophoresis.

Acute Disease↗
PubMed2002

Studies with black tea and its constituents on leukemic cells and cell lines.

The anticancer effect of black tea (BT) and its polyphenols theaflavin (TF) and thearubigin (TR) has been evaluated on U-937 cell line, a myeloid leukemic cell line and on leukemic cells isolated from peripheral blood of chronic myeloid leukemia (CML) patients. In both types of cells, cell growth inhibition was observed 24 hrs after treatment with BT, TF and TR. MTT assay showed growth inhibition of metabolically active cells and inhibition of DNA synthesis was observed by 3H-Thymidine incorporation after treatment with the compounds. In all cases TF and TR were more effective than BT, suggesting that these are possibly the active components in BT responsible for its antileukemic activity. Superoxide dismutase (SOD), a free radical scavenger, was found to be increased by TF, whereas BT and TR lowered the level in comparison to the control. The present study is the first report of antileukemic effect of BT and its polyphenols.

Anticarcinogenic Agents↗
PubMed2001

Quantitative determination of aflatoxin B1-oxime by column liquid chromatography with ultraviolet detection.

Liquid chromatography was used for the quantification of aflatoxin B1-oxime (AFB1-oxime). The yield of AFB1-oxime in the reaction mixture was 89%, while after purification on silica gel it was 72%. LC analysis of the reaction mixture after silica gel fractionation revealed a retention time of 0.84 min for AFB1-oxime, 8.42 min for AFB1, 1.21 min for unknown 1 and 1.61 min for unknown 2. UV-visible analysis of the reaction mixture after silica gel fractionation showed a lambda(max) of 269 and 361 nm for AFB1-oxime, 263 and 360 nm for AFB1, 273 nm for unknown 1 and 275 nm for unknown 2. Excitation and emission wavelengths were found to be 269 and 368/438 nm for AFB1-oxime, 359/424 nm for AFB1, 270 and 367/450 nm for unknown 1 and 273 and 416/447 nm for unknown 2. The method may find versatile application in monitoring reactions for the preparation of oximes of various analytes for the synthesis of their immunogens.

Aflatoxin B1↗
PubMed2001

Full-length cDNAs: more than just reaching the ends.

The development of functional genomic resources is essential to understand and utilize information generated from genome sequencing projects. Central to the development of this technology is the creation of high-quality cDNA resources and improved technologies for analyzing coding and noncoding mRNA sequences. The isolation and mapping of cDNAs is an entrée to characterizing the information that is of significant biological relevance in the genome of an organism. However, a bottleneck is often encountered when attempting to bring to full-length (or at least full-coding) a number of incomplete cDNAs in parallel, since this involves the nonsystematic, time consuming, and labor-intensive iterative screening of a number of cDNA libraries of variable quality and/or directed strategies to process individual clones (e.g., 5' rapid amplification of cDNA ends). Here, we review the current state of the art in cDNA library generation, as well as present an analysis of the different steps involved in cDNA library generation.

Automation↗
PubMed2001

Hypoxia-induced proliferative response of vascular adventitial fibroblasts is dependent on g protein-mediated activation of mitogen-activated protein kinases.

Hypoxia has been shown to act as a proliferative stimulus for adventitial fibroblasts of the pulmonary artery. The signaling pathways involved in this growth response, however, remain unclear. We tested the hypothesis that hypoxia-induced proliferation of fibroblasts would be dependent on distinct (compared with serum) activation and utilization patterns of mitogen-activated protein (MAP) kinases initiated by Galpha(i/o) proteins. We found that hypoxia stimulated increases in DNA synthesis and growth of quiescent fibroblasts in the absence of exogenous mitogens and also markedly augmented serum-stimulated growth responses. Hypoxia caused a transient activation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), the time course and pattern of which was somewhat similar to that induced by serum but which was of lesser magnitude. On the other hand, hypoxia-induced activation of p38 MAP kinase was biphasic, whereas serum-stimulated activation of p38 MAP kinase was transient, and the magnitude of activation was greater for hypoxia compared with that of serum stimulation. ERK1/2, JNK1, and p38 MAP kinase but not JNK2 were necessary for hypoxia-induced proliferation because PD98059, SB202190, and JNK1 antisense oligonucleotides nearly ablated the growth response. JNK2 appeared to act as a negative modulator of hypoxia-induced growth because JNK2 antisense oligonucleotides led to an increase in DNA synthesis. In serum-stimulated cells, antisense JNK1 oligonucleotides and PD98059 had inhibitory effects on proliferation, whereas SB202190 led to an increase in DNA synthesis. Pertussis toxin, which blocks Galpha(i/o)-mediated signaling, markedly attenuated hypoxia-induced DNA synthesis and activation of ERK and JNK but not p38 MAP kinase. We conclude that hypoxia itself can act as a growth promoting stimulus for subsets of bovine neonatal adventitial fibroblasts largely through Galpha(i/o)-mediated activation of a complex network of MAP kinases whose specific contributions to hypoxia-induced proliferation differ from traditional serum-induced growth signals.

Animals↗
PubMed2001

Deletion of the p27Kip1 gene restores normal development in cyclin D1-deficient mice.

D-type cyclins (cyclins D1, D2, and D3) are key components of cell cycle machinery in mammalian cells. These proteins are believed to drive cell cycle progression by associating with their kinase partners, cyclin-dependent kinases, and by directing phosphorylation of critical cellular substrates. In addition, D-cyclins play a kinase-independent role by sequestering cell cycle inhibitors p27(Kip1) and p21(Cip1). In the past, we and others generated cyclin D1-deficient mice and have shown that these mice display developmental abnormalities, hypoplastic retinas, and pregnancy-insensitive mammary glands. To test the significance of cyclin D1-p27(Kip1) interaction within a living mouse, we crossed cyclin D1-deficient mice with mice lacking p27(Kip1), and we generated double-mutant cyclin D1(-/-)p27(-/-) animals. Here we report that ablation of p27(Kip1) restores essentially normal development in cyclin D1-deficient mice. Our results provide genetic evidence that p27(Kip1) functions downstream of cyclin D1.

Animals↗
PubMed2001

Trigonella foenum graecum (fenugreek) seed extract as an antineoplastic agent.

The antineoplastic effect of Trigonella foenum graecum seed extract has been evaluated in the Ehrlich ascites carcinoma (EAC) model in Balb-C mice. Intra-peritoneal administration of the alcohol extract of the seed both before and after inoculation of EAC cell in mice produced more than 70% inhibition of tumour cell growth with respect to the control. Treatment with the extract was found to enhance both the peritoneal exudate cell and macrophage cell counts. The extract also produced a significant antiinflammatory effect. We report here the antiinflammatory and antineoplastic effects, of Trigonella foenum graecum seed extract.

Animals↗
PubMed2001

Assessment of the total number of human transcription units.

Variation in the estimates of the number of genes encoded by the human genome (28,000-120,000) attests to the difficulty of systematically identifying human genes. Sequencing of human chromosome 22 (Chr22) provided the first comprehensive, unbiased view of an entire human chromosome, and intensive analysis of this sequence identified 545 genes and 134 pseudogenes that had similarity or identity to known proteins and/or ESTs and which were listed in the gene annotation (http://www.sanger.ac.uk/HGP/Chr22). This analysis yielded an estimate of approximately 36,000 functional expressed genes in the human genome (and 9000 pseudogenes). However, a key uncertainty in this estimate was that hundreds of additional genes beyond those annotated in the Chr22 sequence are predicted by the gene prediction program Genscan, an unknown number of which might represent additional expressed genes. To determine what fraction of these "predicted novel genes" (PNGs) represents expressed human genes, we used a sensitive RT-PCR assay to detect predicted transcripts in 17 tissues and one cell line. Our results indicate that at least 5000-9000 additional human genes which lack similarity to known genes or proteins exist in the human genome, increasing baseline gene estimates to approximately 41,000-45,000.

Chromosomes, Human, Pair 22↗
PubMed2001

Role of biological antioxidants in benzanthrone toxicity.

Previous studies indicate that benzanthrone, an anthraquinone dye intermediate, caused significant depletion of ascorbic acid (AsA). In this investigation the effect of benzanthrone on the status of different forms of AsA and other bio-antioxidants such as glutathione (GSH) was studied. Oral administration of benzanthrone (50, 125 or 250 mg/kg body weight) resulted in a significant increase of urinary AsA levels with a concomitant decrease in the urinary dehydroascorbic acid (DHA) content in both rats and guinea-pigs. Benzanthrone caused a dose-dependent decrease in hepatic, adrenal and serum AsA levels with a subsequent increase in DHA and diketogulonic acid (DKA) levels in both rats and guinea-pigs. Following benzanthrone treatment, rats showed an increase in the scorbutic index (to 1.01-1.21) of the liver, adrenal glands and serum compared to controls (0.12-0.24). The scorbutic indices of liver, adrenal glands and serum were also substantially increased (to 3.61-11.20) in benzanthrone-treated guinea-pigs compared to controls (0.16-0.38). Single oral administration of benzanthrone to guinea-pigs caused a dose-dependent depletion of GSH in liver (15-51%), adrenal glands (27-64%) and serum (32-86%). Furthermore, the depletion of GSH by benzanthrone in rats was of a lesser degree. This suggests that continued exposure of guinea-pigs to benzanthrone may lead to scurvy-type changes in this animal species but not to the same extent in rats, since the latter has the enzymatic capacity to synthesise AsA. Therefore, it can be hypothesised that benzanthrone per se, or its metabolites, interact with reduced GSH thereby causing its depletion. Furthermore, in order to replenish the depleted GSH levels, AsA might be oxidized to DHA and hence the decrease in AsA with the simultaneous increase in DHA was observed.

2,3-Diketogulonic Acid↗
PubMed2001

Variable severity of beta-thalassemia patients of eastern India: effect of alpha-thalassemia and xmnI polymorphism.

Sixty-four thalassemia and E-beta thalassemia patients were studied for factors that modulate the severity of the disease; i.e., mutation of beta-globin gene, presence of alpha-deletion, and presence of an XmnI site at the -158 position of the Gy gene. Presence of alpha-deletion and/or homozygosity for the XmnI site was in general associated with less-severe disease. About 12% of the patients harbored single alpha-gene deletion, and the gene frequency of the XmnI polymophism in these patients is 0.48.

Deoxyribonucleases, Type II Site-Specific↗
PubMed2001

Characterization of de-emulsification capabilities of a Micrococcus species.

Effect of post harvest washing as well as cell concentration on de-emulsification characteristics of an isolated Micrococcus species has been tested with Tween 60 Span 60 stabilised oil in water (o/w) and L-92 pluronic surfactant stabilised water in oil (w/o) model emulsions (kerosene water). The cells used were 140 h old and grown under submerged conditions at 37 degrees C in a medium containing n-tetradecane (4% v/v) as the carbon source. The harvested bacterial cells when in an unwashed condition (at a cell concentration of 2 mg/ml of emulsion) were found to de-emulsify the o/w system at a much faster rate than the w/o system exhibiting half-life values for the respective system as 10.2 and 127.7 h. Post harvest washing of the cells with any lipid solubilising solvent (n-pentane, n-hexane, kerosene, chloroform-methanol-water (CMW)) yielded a decrease in their de-emulsification power for w/o emulsion. But the decay of o/w emulsion became faster with n-pentane- and kerosene-washed cells as evident from their corresponding half-life values of 3.3 and 4.6 h. Compared to the w/o system, an increase in the concentration of kerosene-washed cell had a direct effect on de-emulsification for the o/w system. For cell concentrations of 2, 3 and 4 mg/ml of the emulsion, the half-life values for the w/o system were 364.8, 442.0 and 454.9 h, respectively. For 2 and 4 mg/ml cell contents, the half-life values for the o/w system were 4.6 and 1.0 h. The decay of both the emulsions was very slow or even incomplete for cell concentrations less than 2 mg/ml. De-emulsifying capacity of the n-tetradecane grown Micrococcus species towards o/w model emulsion improved considerably after washing the cells with n-pentane and kerosene, and use of kerosene-washed cells (4 mg/ml) reduced the half-life to 1 h.

Biodegradation, Environmental↗
PubMed2001

First aid and basic life support skills training early in the medical curriculum: curriculum issues, outcomes, and confidence of students.

BACKGROUND: The importance of training physicians and other health care professionals in first aid and basic life support (BLS) is now widely recognized. The Faculty of Medicine and Health Sciences of the United Arab Emirates University have been offering formal training in these skills to 1st-year medical students since 1989. The aim of this study was to determine the efficacy of the program and the extent to which it provides students with confidence to perform skills on their own after training. DESCRIPTION: 165 of 180 male and female students comprising 3 cohorts (91.7% response rate) completed a self-administered anonymous questionnaire. The questionnaire contained open- ended and Likert-type questions regarding course organization, content, strengths and weaknesses, teaching--learning approaches, and skills development and confidence. The authors analyzed assessment outcomes and associations between self-perceived levels of confidence and ability to practice. EVALUATION: Students were uniformly enthusiastic and highly motivated by the program. Self-assessed confidence in ability to perform skills on their own after completing the program was moderately correlated with perceived frequency of opportunity to practice many skills. There was nevertheless a consistent desire for more practice time. CONCLUSIONS: The results suggest that the program provides students with sound basic knowledge and adequate practical skills in first aid and BLS and that adequacy of time and physical and human resources are important prerequisites to facilitate practice and engender confidence in skills.

Cardiopulmonary Resuscitation↗
PubMed2001

Hydrogen peroxide induces apoptosis-like death in Leishmania donovani promastigotes.

Leishmania donovani promastigotes introduced into the bloodstream by sandfly vectors, are exposed to reactive oxygen species like H2O2 during phagocytosis by the host macrophages. H2O2 can induce promastigote death, but the mechanism of induction of this death is not known. Studies presented in this paper demonstrate that exposure to 4 mM H2O2 results in a pattern of promastigote death that shares many features with metazoan apoptosis. Motility and cell survival in these parasites show a gradual decline with increasing doses of H2O2. Features common to metazoan apoptosis, such as nuclear condensation, DNA fragmentation with accompanying DNA ladder formation and loss of cell volume, are observed after exposure to 4 mM H2O2. Within 30 minutes of the exposure, there is a significant increase in the ability of the cell lysates to cleave the fluorogenic tetrapeptide acetyl-Asp-Glu-Val-Asp-7-amino-4-trifluoromethyl coumarin, which is a substrate for the CED-3/CPP32 group of proteases. Pretreatment of cells with a specific inhibitor of CED-3/CPP32 group of proteases, Z-DEVD-FMK, reduces the number of cells showing apoptosis-like features, prevents DNA breakage and inhibits cleavage of a PARP-like protein. Activation of the caspase-like proteases is followed at 2 hours by the cleavage of a poly(ADP)ribose-polymerase-like protein and a reduction in intracellular glutathione concentration. DNA breakdown as detected by TdT labelling of cells and agarose gel electrophoresis is visible at 6 hours. Taken together, the above data show for the first time that there is a distinct pathway for apoptosis-like death in L. donovani.

Animals↗
PubMed2001

Mycobacterial pulmonary infection post allogeneic bone marrow transplantation.

Allogeneic bone marrow transplant recipients are prone to pulmonary infections caused by a wide spectrum of organisms. Since the first bone marrow transplatation (BMT) done in 1983 at the Tata Memorial Hospital, we have recently seen the first case of Mycobacterium Fortuitum Chelonae complex among 117 BMT (including 90 allogeneic and 27 autologous) patients. The patient was on immunosuppressants for chronic GVHD post allogeneic BMT done for CML-CP. He developed pulmonary mycobacterial infection 13 months post BMT. Diagnosis was difficult because of the atypical presentation, negative culture reports, and the presence of multiple pathogens due to immunosuppression. In our case the diagnosis was eventually established after examination of material obtained by bronchoscopy. Patient has shown response to antituberculosis drugs after 2 months. This shows the need to consider atypical mycobacterial infection in the differential diagnosis of pulmonary illness in the post allogeneic BMT setting.

Adult↗