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Biomedical subjects

S Ray

Publications and source records attributed to S Ray.

At least 91 records · Page 5Linked to original sources
PubMed1990

Studies on synergism between penicillins and ambodryl (bromodiphenhydramine HCl), an antihistamine with antimicrobial property.

With respect to 31 different selected test bacteria, all sensitive to benzyl penicillin (Pc), ampicillin (Ap), methicillin (Me), ceporan (Ce), cloxacillin (Cx), streptomycin (Sm), kanamycin (Km), gentamicin (Gm), chloramphenicol (Cm), tetracycline (Tc), polymyxin (Pm) as well as ambodryl [Am; an antihistamine (bromodiphenhydramine HCl) with distinct antimicrobial properties], it was found that Am in combination either with Pc, Ap, Ce or Me consistently showed enhancement of antimicrobial effects resulting from synergism. A combination of Am with either Sm, Km, Gm or Tc, on the other hand, showed only additive effects. An interaction of the activities of Am with Pm also resulted in indifference effects. Determination of the area of inhibition zone, calculated from its diameter for the degree of synergism in case of Am and Pc, showed these synergistic effects to be significant (P less than 0.05) in comparison with their individual effects: this was corroborated by the determination of the fractional inhibitory concentration (FIC) index which was found to be less than 0.5. The synergism of Am-Pc combination was confirmed by in vivo studies by challenging mice with a virulent strain of S. typhimurium and looking for protection.

Bacteria↗
PubMed1990

Acid excretion and serum electrolyte patterns in patients with advanced chronic renal failure.

Hyperchloremic metabolic acidosis can be seen in advanced chronic renal failure (CRF). To study this further, we measured acid excretion under controlled conditions in 19 patients with severe but stable CRF. Twelve patients had a hyperchloremic metabolite acidosis, 3 had an elevated anion gap acidosis ('delta acidosis'), while the 4 remaining patients had a slightly decreased tCO2 with a normal anion gap and serum chloride level ('mild acidosis'). Ammonium excretion was markedly reduced in CRF patients (11 +/- 1 vs. 32 +/- 2 mEq/day in normal subjects, p less than 0.005), and likewise urinary titratable acid was diminished (18 +/- 2 mEq/day in patients, vs. 28 +/- 3 mEq/day in normal subjects; p less than 0.005). When expressed per 100 ml GFR, ammonium and titratable acid excretion were markedly increased in all groups of patients compared to normal subjects. The Tm for bicarbonate was 22.5 +/- 3.7 mEq/l for all CRF patients and 24 +/- 1 mEq/l for the patients with a hyperchloremic metabolic acidosis. We conclude that the hyperchloremic metabolic acidosis in advanced renal failure is due to diminished excretion of ammonium and titratable acid and is not due to an increased bicarbonate leak. As renal failure advances and renal mass declines, the remaining functioning nephrons hypersecrete acid.

Acidosis↗
PubMed1990

Pattern of acute myocardial infarction in a district hospital in Brunei Darussalam--a pilot study.

The objective of the authors was to study the pattern of presentation, risk factors, and natural course of acute myocardial infarction in the general population of Belait District in Brunei Darussalam. A prospective study was done of 100 consecutive cases of acute myocardial infarction admitted to the coronary care beds of a District General Hospital. The patients were followed up to 12 weeks after admission to hospital. There were three times more males than females (75 males, 25 females). Nine cases out of 75 males were below the age of 40 years, 3 being below 30 years. The mean age of the male denominator was 57.4 years while that of the female counterpart was 67.48 years showing a mean difference of 10.08 years. There were significant association with hypertension (31%), smoking (30%) and diabetes mellitus (27%). The majority of the patients had prodromal symptoms, the most common presenting symptoms were chest pain (63%) and shortness of breath (27%). Only 4% of the patients had silent infarction. Acute myocardial infarction is common in Brunei forming 2.6% of all the patients admitted to the medical wards and the relative rate is 3 times higher in males than in females. There is significant association of IHD with 3 main risk factors namely hypertension, smoking and diabetes mellitus.

Adult↗
PubMed1990

Physiological changes in rats after exposure to low levels of microwaves.

The effects of exposure to sublethal levels of microwaves were studied. Young albino rats of both sexes were exposed for 60 days to 7.5-GHz microwaves (1.0-KHz square wave modulation, average power 0.6 mW/cm2) for 3 h daily. During and after microwave exposure several physiological parameters were measured in both control and exposed animals. It was found that the animals exposed to microwaves tended to eat and drink less and thus showed a smaller gain in body weight. Some of the hematological parameters and organ weights were also significantly different. It is proposed that a nonspecific stress response due to microwave exposure and mediated through the central nervous system is responsible for the observed physiological changes.

Animals↗
PubMed1990

Prevalence of hepatitis-B surface antigen in the pregnant women of Brunei Darussalam.

In view of the high incidence of mother-to-child transmission of hepatitis B virus (HBV), routine screening of pregnant at antenatal clinic and vaccination of the newborn has become a common practice throughout the world. The prevalence of HBsAg in pregnant women of Brunei Darussalam was assessed. Of 1,267 pregnant women who attended the antenatal clinic of Suri Seri Begawan Hospital, Kuala Belait, the overall prevalence of HBsAg was 3.2% with significant differences in various ethnic groups (p less than 0.05). Malays, who form the major ethnic group had the lowest rate of 1.9%.

Adolescent↗
PubMed1989

Methylglyoxal-catabolizing enzymes of Leishmania donovani promastigotes.

Methylglyoxal is a toxic metabolite with growth inhibitory properties against Leishmania donovani promastigotes. We have shown in the present study that both log and stationary phase promastigotes of L. donovani can catabolize methylglyoxal to D-lactate as the major end product. The specific activity of methylglyoxal reductase was found to be the highest of all the catabolic enzymes. In contrast, the anabolic pathway for methylglyoxal could not be detected. Moreover, when control promastigotes or promastigotes in which the glycolytic pathway was inhibited were incubated with glucose, glycerol or dihydroxyacetone phosphate as energy source, neither methylglyoxal nor D-lactate could be detected.

Alcohol Oxidoreductases↗
PubMed1989

Accuracy of inpatient oxygen administration.

The accuracy of supplemental oxygen delivery was assessed in two medical units. Only 90 of 206 patients (44%) were receiving oxygen as prescribed. The ward oxygen rotameters were inaccurate at normal clinical flow rates, the range of flows being delivered as a percentage of the indicated flow varying from 15% at 8 l/min to 40% at 1 and 2 l/min.

Equipment Design↗
PubMed1989

Female breast engorgement on ranitidine--a case report.

A 60 year old woman with chronic duodenal ulcer not responding to Cimetidine, was changed to Ranitidine. She had symptomatic improvement, but had bilateral breast engorgement and tenderness for which treatment was discontinued. A therapeutic trial on a second occasion had the same side effect which came on more rapidly and quickly. This complication in such severe form and recurrence on rechallenge requiring withdrawal of drug was observed for the first time with any H2 receptor antagonist.

Breast Diseases↗
PubMed1989

Stimulation of DNA chain initiation by a protein factor (NPF-1) from rat liver of different ages.

DNA Polymerase-alpha/primase complexes have been isolated from human neuroblastoma IMR-32, embryonic chicken brains (ECB) and rat prostate tumor PA-3 cells. In the presence of (NH4)2SO4 the major part (90%) of primase activity is released from the Pol-alpha/primase complex. A novel hydrophobic interaction column was used for purification of the primase from PA-3 cells. A nuclear protein factor (NPF-1) that stimulates DNA pol-alpha/primase activity has been purified from rat liver of various ages (3-6 months). The nuclear protein factor which only stimulates the primase activity is under investigation. The monoclonal antibodies (SJK 132-20 and 237-71) were used to detect DNA pol-alpha polypeptides from 11- to 19-day-old embryonic chicken brains.

Aging↗
PubMed1989

Beneficial effects of ACE inhibitors in severe mitral stenosis.

There are several reports of beneficial effects of ACE inhibitors in both primary and secondary pulmonary hypertension. However the effect of ACE inhibitors in mitral stenosis is not documented. The authors report three patients with severe mitral stenosis in whom surgery was delayed. They had initial symptomatic improvement with diuretics and sodium restriction, but had recurrence of their symptoms while on treatment. Enalapril not only relieved their symptoms in particular exertional dyspnoea and haemoptysis but prevented recurrence and improved their effort tolerance without causing excessive fall of blood pressure or impairment of renal function.

Adult↗
PubMed1989

Hepatitis-B surface antigen and VDRL in healthy blood donors of Brunei Darussalam.

We screened 3276 voluntary blood donors for Hepatitis-B surface antigen (HBsAg) and VDRL. The results were analysed to assess the prevalence and the possible relation to age, sex, race and blood group. Our present study was done in Belait District of Brunei Darussalam where we have a mixed population of various racial groups namely Malays, Chinese, Ibans, Dusuns, Kelabits, Kadazans, Nepalese, Filipinos, Thais, Koreans, Eurasians, Indians, British, Dutch, Americans, Africans and Australians. Our findings suggest that the prevalence of HBsAg is 4.71% and that of VDRL is 0.64% of the donor population. HBsAg positivity rate among various blood groups is found to be not statistically significant (p greater than 0.05). However, this rate is found to be highly significant among racial groups (p less than 0.001) and the rate of positivity of VDRL is also found to be significantly different among racial groups (p less than 0.01), with the highest percentage of both being in the Ibans.

Age Factors↗
PubMed1988

Electrical parameters of bone substrate in microstrip line configuration.

Techniques of microstrip line are extended to study the dielectric properties of bone at 4.5 GHz. The method is based on time domain technique and is applicable to higher frequency ranges where other conventional methods of dielectric measurements are not suitable. It is found that this method serves well for the determination of dielectric constants of bone in two orthogonal directions.

Animals↗
PubMed1988

C-nor-9,11-secoestranes as modified estrogens and fertility regulation.

The synthesis of C-nor-9,11-secoestradiol (4) has been achieved from 17 beta-acetoxy-11-chloro-3-methoxy-C-nor-9,11-secoestra-1,3,5(10)-tr ien-9-one (1) through a sequence of reactions without affecting the stereochemistry of estradiol-17 beta. Removal of the 9-keto function of 1 by hydrogenolysis and its subsequent treatment with Na/NH3 gives C-nor-9,11-secoestradiol 3-(methyl ether) (3), which has been demethylated under alkaline conditions to furnish C-nor-9,11-secoestradiol (4). Pyridinium chlorochromate oxidation of 3 gives the corresponding 17-ketone 6. Jones' oxidation of 4 to the ketone 5 and reaction of 5 and 6 with lithium acetylide gives corresponding 17 alpha-ethynyl derivatives 7 and 8. Relative binding affinity to estradiol-17 beta receptors and uterotropic, antiuterotrophic, and antiimplantation activities of compounds 3-8 have been studied. The effect of conformational flexibility on ligand-receptor interaction of these compounds is discussed.

Animals↗
PubMed1988

Early neoplastic commitment of hamster buccal pouch epithelium exposed biweekly to 7,12-dimethylbenz[a]anthracene.

Experiments were performed to determine the rate at which hamster buccal pouch epithelium (HBPE) is committed to neoplastic development during a regimen of biweekly topical applications of 7,12-dimethylbenz[a]anthracene (DMBA) in mineral oil, administered for 1, 2, 3, 5 or 10 weeks. Evaluated indices of neoplastic commitment were: (i) primary tumor formation, (ii) passageability of HBPE cells in surface culture, (iii) anchorage-independent growth in soft agar and (iv) induction of the transformed phenotype in NIH3T3 cells following transfection with HBPE DNA. Groups of 12-15 hamsters, exposed to DMBA for 1, 2 and 3 weeks, developed buccal pouch tumor incidences of 13%, 42% and 71% respectively within 44 weeks. Buccal pouches of ten control hamsters treated for three weeks with mineral oil did not develop buccal pouch neoplasms during an observation period of 44 weeks. Whereas cultured HBPE cells obtained following three weeks of in vivo DMBA exposure were negative in assays for anchorage-independent growth, passageability in surface culture and induction of NIH3T3 transformants following DNA transfection, similarly cultured cells obtained following five and ten weeks of in vivo exposure were positive, or marginally positive, in each of these assays. These results indicate that (i) the regimen of biweekly DMBA applications commits HBPE to neoplastic development within three weeks and that (ii) subsequent cellular or molecular changes occurring during greater than or equal to 2 succeeding weeks of DMBA treatment are necessary to manifest the transformation associated phenotypes of continuous passageability, anchorage-independent growth, and induction of NIH3T3 transformants following DNA transfection.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

Vitamin D, its precursors, and metabolites do not affect melanization of cultured human melanocytes.

Exposure of the skin to sunlight results in both tanning and vitamin D3 production. It has therefore been suggested that vitamin D3 or its active metabolite 1,25-dihydroxyvitamin D3 may be the mediator of UV-induced melanogenesis. To test this hypothesis, newborn foreskin-derived melanocytes were cultured in paired dishes in hormone-supplemented medium with 2% serum containing no detectable vitamin D3 or in the same medium containing 10(-8) or 10(-10) M of either provitamin D3, lumisterol, previtamin D3, vitamin D3, 25-hydroxyvitamin D3, or 1,25-dihydroxyvitamin D3. After 10 days, cell number in cultures containing vitamin D compounds was 93%-140% of unsupplemented controls and melanin content was 60%-120% of control, with no significant difference in either parameter for any compound tested. In separate experiments, human melanocytes and Cloudman S91 melanoma cells were repeatedly irradiated with physiologic doses of simulated sunlight and incubated between irradiations with provitamin D3, previtamin D3, vitamin D3, or 1,25-dihydroxyvitamin D3. Irradiated cultures had a 90%-95% inhibition of cell growth associated with a 200%-800% increase in melanin content per cell relative to controls, but there was no effect of any vitamin D compound on either cell type. Neither cultured human melanocytes nor S91 cells showed evidence of the cytosolic 1,25-dihydroxy-vitamin D3 receptor binding by sucrose density gradient analysis using radiolabeled 1,25-dihydroxyvitamin D3. The combined data strongly suggest that neither vitamin D3 nor its precursors or metabolites directly mediate melanogenesis in these cells.

Cells, Cultured↗