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Biomedical subjects

B Das

Publications and source records attributed to B Das.

At least 217 records · Page 12Linked to original sources
PubMedDate not supplied

Combined action of inhibitors of polyamine biosynthetic pathway with a known antimalarial drug chloroquine on Plasmodium falciparum.

Difluoromethylornithine (alpha-DFMO), a specific enzyme activated inhibitor of ornithine decarboxylase activity, a bis (benzyl) polyamine analogue (MDL 27695) and chloroquine resulted in a dose-dependent inhibition of the parasite. The IC50 value of alpha-DFMO, MDL 27695 and chloroquine was 1.85 mM, 2.0 microM and 23 ng ml-1 respectively. The combined action of MDL 27695 (3 microM) and chloroquine (5 ng ml-1) on P. falciparum growth showed near additive effect, whereas the combination of alpha-DFMO (1.0 mM) and chloroquine (5 ng ml-1) was more than the effect of each drug individually but not additive. Similarly the combined effect of MDL 27695 (3 microM) and alpha-DFMO (1.0 mM) on P. falciparum growth was not additive. The effect of these inhibitors alone and in combination on polyamine biosynthesis is also reported.

Animals↗
PubMedDate not supplied

Effect of nonaxisymmetric hematocrit distribution on non-Newtonian blood flow in small tubes.

Hematocrit distribution and red blood cell aggregation are the major determinants of blood flow in narrow tubes at low flow rates. It has been observed experimentally that in microcirculation the hematocrit distribution is not uniform. This nonuniformity may result from plasma skimming and cell screening effects and also from red cell sedimentation. The goal of the present study is to understand the effect of nonaxisymmetric hematocrit distribution on the flow of human and cat blood in small blood vessels of the microcirculation. Blood vessels are modeled as circular cylindrical tubes. Human blood is described by Quemada's rheological model, in which local viscosity is a function of both the local hematocrit and a structural parameter that is related to the size of red blood cell aggregates. Cat blood is described by Casson's model. Eccentric hematocrit distribution is considered such that the axis of the cylindrical core region of red cell suspension is parallel to the axis of the blood vessel but not coincident. The problem is solved numerically by using finite element method. The calculations predict nonaxisymmetric distribution of velocity and shear stress in the blood vessel and the increase of apparent viscosity with increasing eccentricity of the core.

Animals↗
PubMedDate not supplied

The ozonation of unsaturated fatty acids: aldehydes and hydrogen peroxide as products and possible mediators of ozone toxicity.

The products of the reactions of ozone with aqueous emulsions of unsaturated fatty acids and with liposomes made from phosphatidylcholine esters were characterized. Ozonolysis of emulsions of methyl oleate yields approximately 1 mol of hydrogen peroxide and 2 mol of aldehydes per mole of ozone used and fatty acid reacted. That is, the net equation that occurs is RCH = CHR' + O3 + H2O----RCHO + R'CHO + H2O2 . Ozonolysis of emulsions of oleic, linoleic, linolenic, and arachidonic acids gives 1 mol of hydrogen peroxide per mole of ozone used. Only very low yields (less than 5%) of reducible materials other than hydrogen peroxide are observed, suggesting that the yields of organic peroxidic materials, including Criegee ozonides and lipid hydroperoxides, are small. Ozonolysis of rat erythrocyte ghost membranes and rat bronchoalveolar lavage also gives significant yields (about 50%) of hydrogen peroxide based on the moles of ozone consumed. Reactions of ozone with bovine serum albumin, glutathione, and glucose do not produce hydrogen peroxide, implying that the hydrogen peroxide formed during the ozonation of biological materials arises almost exclusively from ozone/olefin reactions. Hydrogen peroxide and aldehydes are suggested to be important mediators of the modifications observed in both the lung and extrapulmonary tissues when ozone is inhaled.

Air Pollutants↗
PubMedDate not supplied

Combined action of inhibitors of S-adenosylmethionine decarboxylase with an antimalarial drug, chloroquine, on Plasmodium falciparum.

Methylglyoxal bis (guanylhydrazone), (MGBG) a potent competitive inhibitor of S-adenosyl-L-methionine decarboxylase activity, Berenil, a trypanocidal agent and chloroquine, the commonly used antimalarial resulted in a dose dependent inhibition of Plasmodium falciparum in vitro. The IC50 values of MGBG, Berenil and chloroquine were 224 microM, 40 microM and 42 nM respectively. Parasites treated with different concentrations of MGBG or Berenil were arrested at the trophozoite stage of the erythrocytic cycle. The combined action of chloroquine (10 nM) with either Berenil (0.1 mM) or MGBG (0.1 mM) on P. falciparum growth showed an additive inhibitory effect. The effect of these inhibitors alone and in combination on polyamine biosynthesis is also reported.

Adenosylmethionine Decarboxylase↗
PubMedDate not supplied

Computer supported studies on design and evaluation of solid dispersions of carbamazepine.

The main advantages of solid dispersions (the drug could be maintained in a bioavailable form, dosage reduction and cleaner manufacturing conditions) provide scope for the continued interest in field. Additionally, their use in providing a sustained or controlled release of drugs has only been tentatively examined. In the present study, Carbamazepine has been used to develop a dosage form which will provide a booster amount followed by sustained release of the drug for effective control of epileptic seizures while keeping the serum level of the drug at minimum. Enteric polymers CAP and CAT have been used to retard the release till the formulation reaches the intestine. Either individually or combined fractions of the formulations may be used in the therapy of epilepsy.

Anticonvulsants↗
PubMedDate not supplied

Carbachol-evoked suppression of excitatory neurotransmission in guinea-pig olfactory cortex slices is unlikely to involve an M4-muscarinic receptor subtype.

Depression of the electrically-evoked surface-negative field potential (N-Wave) by bath-superfusion of carbachol was measured in guinea-pig olfactory cortex slices maintained in vitro. The possibility that this response, previously proposed to be mediated via a presynaptic M1: muscarinic receptor, might in fact be due to M4 receptor activation, was investigated by testing the effectiveness of himbacine (a proposed M4-selective antagonist) on our cortical preparation. Himbacine (100 nM-1 microM) had no effect on the N-wave potential alone, but it induced a clear competitive-type inhibition of carbachol effects. Schild plot analysis (regression slope constrained to unity) of pooled data yielded a pA2 value of 7.2 for this antagonist (n = 7 slices). This value accords more with that expected for the interaction of himbacine with M1 receptors (approximately 7.2) than with functionally expressed M4 receptors (approximately 8.5-8.5). We therefore conclude that M4-type muscarinic receptors are unlikely to be involved in mediating this presynaptic carbachol response.

Alkaloids↗
PubMedDate not supplied

Kushtha (skin disorders) in vedic and other religious literatures - A review.

In view of the description of Medical citations; Vedic literature, Buddhist literature, Jain literature, Mahabharat, Ramayan etc. have also got significant importance. Like other diseases, the description regarding Kushtha (different skin disorders) is also available in all these treatises. These are akin to the description available in Ayurveda. From the above, it is apparent that description of different diseases mentioned in Ayurveda are also available in religious literatures.

History, Ancient↗
PubMedDate not supplied

Dimensions of potential arterial grafts for coronary artery bypass grafting in Indians--an autopsy evaluation study.

Total revascularization of the heart using as many arterial grafts as possible is the trend of the day. We have chosen two commonly used arterial grafts to evaluate their efficiency in myocardial revascularization in Indian subjects. An autopsy study was conducted in 25 cases. Both internal mammary arteries with their branches and the right gastroepiploic artery were harvested. These arteries were distended with heated Gelatin, deep frozen and their diameters were measured. In 56% of subjects diameter of internal mammary artery was 1.5 to 2.0 mm (n = 14). However 36% of subjects had diameter above 2.0 mm (n = 9). Musculo-phrenic and superior epigastric arteries had 1.85 and 1.65 mm internal diameters respectively. The mean internal diameter of right gastro-epiploic artery was 2.3 mm. When these diameters were indexed to the body surface area, they were comparable with similar figures from western subjects.

Anthropometry↗
PubMedDate not supplied

Immunohistochemical characterization of Aschoff nodules and endomyocardial inflammatory infiltrates in resected left atrial appendages.

Presence of Aschoff nodules and other chronic inflammatory cells in the left atrial appendage even in the absence of rheumatic activity has been reported in a high percentage of patients with chronic rheumatic valvular heart disease. This study was conducted on 37 left atrial appendages resected at the time of closed mitral valvotomy. Aschoff nodules were present in 61.2 percent of resected appendages, positivity being 71.4 percent in the age group of 20 years of less and 53.3 percent in patients more than 20 years of age. The histological findings did not change significantly in the presence of activity. The frequency of Aschoff nodules and chronic inflammatory cells and their subtypes also did not show any correlation with age, sex, duration of symptoms or severity of mitral stenosis.

Adult↗
PubMedDate not supplied

Our experience with surgical management of patients with diffuse coronary artery disease.

During a follow up period of 5 years (January 1983-December 1988), 145 consecutive patients (14% of all patients undergoing coronary artery bypass surgery) underwent multiple coronary artery bypass grafting combined with endarterectomy whenever necessary for treatment of severe diffuse triple-vessel coronary artery disease. Fifty-one patients (35%) had poor left ventricular ejection fraction (less than 35%). Associated left main coronary artery disease was present in 30 (21%) patients. All coronary arteries and branches with greater than 50% obstructive disease were bypassed, using saphenous vein conduit; average grafts per patient were 5.5. Endarterectomies were done in 137 patients in 210 vessels. Right coronary artery was the commonest site (132 patients). Multiple vessel endarterectomy (greater than 2 vessels) was done in 44 patients (30%). The peri-operative mortality was 3.5%. Pre-operatively, 75% patients had class III and 14% class IV (Canadian Cardiovascular Society angina criteria). During the mean follow up period of 2 years, 86% patients have class 1 symptoms, and 14% have class II symptom. Thirty of these 145 patients have undergone resting and exercise radionuclide ventriculographic studies which have shown a significant improvement in the ejection fraction response to exercise (p less than 0.05). Thus, patients with severe diffuse coronary disease can undergo multiple bypass grafting procedure, along with endarterectomies with low mortality rates and improved exercise tolerance and functional classification.

Adult↗