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Biomedical subjects

K Singh

Publications and source records attributed to K Singh.

At least 469 records · Page 26Linked to original sources
PubMed1989

Two-year follow-up of changes in clinical chemistry in Singaporean Norplant acceptors: haemostatic changes.

A longitudinal study of coagulation parameters was carried out on 100 Singaporean acceptors using Norplant for contraceptive purposes. At the end of 2 years of use, results from this ongoing study indicate that these acceptors continue to have an increased predisposition to thrombosis as evidenced by significant increases in platelet count and aggregability. The shortened but stable prothrombin time and activated partial thromboplastin time and increase in certain coagulation factors indicate that Norplant acceptors still have a possible potential for hypercoagulation at the end of two years of use.

Blood Coagulation↗
PubMed1989

Two-year follow-up of changes in clinical chemistry in Singaporean Norplant-2 rod acceptors: metabolic changes.

In this longitudinal study involving 100 Singaporean acceptors, the effects of Norplant-2 rods on metabolic function was evaluated. The mean serum bilirubin during the second year remained significantly raised from its preinsertion value (p less than 0.001). Furthermore the total proteins and globulin were still significantly decreased (p less than 0.001). Thus with respect to liver function, the results still indicate possible dysfunction at the end of two years. As regards lipid metabolism, the serum triglycerides, total cholesterol and LDL-cholesterol still remained significantly decreased at the end of two years when compared to preinsertion values. The HDL-cholesterol levels which showed no significant change during the first year of use decreased significantly during the second year of use. As a result the HDL-cholesterol/Total cholesterol - HDL-cholesterol decreased significantly and was 12.0% lower than the pre-insertion ratio (p less than 0.01). Similarly the LDL-cholesterol/HDL-cholesterol increased during the second year of use and was 2.6% higher than its preinsertion ratio. However, this increase was still not statistically significant. As we have not incorporated a simultaneous non-steroid treated control group, the observed changes in lipid metabolism could be attributed to extraneous factors such as diet, exercise or other environmental changes. Nevertheless, the findings at the end of two years, though speculative, still indicate Norplant-2 use to be non-contributory to cardiovascular risk in this population. The use of Norplant-2 was not associated with any significant effect on glucose tolerance after two years of use.

Bilirubin↗
PubMed1989

Two-year follow-up of changes in clinical chemistry in Singaporean Norplant-2 rod acceptors: haemostatic changes.

A longitudinal study of coagulation parameters was carried out on 100 Singaporean acceptors using Norplant-2 rods for contraceptive purposes. At the end of 2 years of use, results from this study show a return of platelet count to preinsertion level while platelet aggregation remained significantly enhanced. Thus the net effect of these two changes on an increased tendency for thrombosis needs further evaluation. The PT and APTT continued to remain persistently shortened during the period of use. There was also a general fall in fibrinogen and most other coagulation factors during the two years of use. Thus, again, the net effect of these two changes on the exposed potential for hypercoagulation at the end of the first year needs further evaluation throughout the five years of Norplant-2 use.

Blood Coagulation↗
PubMed1989

Saturation mutagenesis of the octopine synthase enhancer: correlation of mutant phenotypes with binding of a nuclear protein factor.

A 16-base-pair palindrome from the Agrobacterium tumefaciens octopine synthase gene functions as a constitutive enhancer in plant protoplasts. Degenerate oligonucleotide mutagenesis provided single base substitutions at every position in the element and a number of multiple base substitutions. The effects of these changes were determined in transient expression assays with tobacco and maize protoplasts. The majority of single and double base changes had little effect on the activity of the octopine synthase enhancer, but nearly all mutants with more than two base changes had low to essentially no activity. There were five positions where particular single base changes resulted in a 4- to 10-fold loss in enhancer activity. The distribution of these positions within the palindrome was asymmetric. Single base deletions had essentially no activity, demonstrating that the octopine synthase enhancer cannot tolerate internal changes in spacing. We find a strong correlation between mutant phenotype and reduced binding of a protein factor, suggesting that the DNA-protein complex is responsible for the transcriptional enhancement; the functionally active form of the DNA-protein complex probably involves more than a single protein molecule. The mutants exhibit similar phenotypes in protoplasts of both tobacco and maize, implying conservation of the DNA-protein interactions of the ocs enhancer sequence in monocotyledonous and dicotyledonous plants.

Amino Acid Oxidoreductases↗
PubMed1989

Studies on lorazepam as a premedicant for thiopental anaesthesia in the dog.

Four mg of lorazepam was given intravenously 5 min prior to thiopental anaesthesia in 5 clinically healthy dogs weighing 14 +/- 2 kg and aged about 10-12 months. Animals required only 7.0 +/- 1.5 ml of 5% thiopental sodium to achieve surgical anaesthesia which lasted about 30.4 +/- 3.3 minutes. There was adequate muscle relaxation and loss of pedal and palpebral reflexes. Five min after administration of lorazepam, there was no appreciable change in various cardiopulmonary dynamics. However, there was moderate arterial hypertension, tachycardia and arterial hypoxemia 15 min after the onset of the thiopental anaesthesia. There was no respiratory depression. The lorazepam-thiopental combination was also attempted in 16 clinical cases varying from repair of fractures of long bones (9), mammary tumour (2), ear haematoma (1), ear cropping (1), tail gangrene (2) and rectal prolapse (1). This combination of anaesthesia proved extremely useful for orthopaedic surgery as the muscle relaxation was adequate and reduction of the fractured ends was comparatively easier.

Anesthesia↗
PubMed1989

Inverse regulation of the yeast COX5 genes by oxygen and heme.

The COX5a and COX5b genes encode divergent forms of yeast cytochrome c oxidase subunit V. Although the polypeptide products of the two genes are functionally interchangeable, it is the Va subunit that is normally found in preparations of yeast mitochondria and cytochrome c oxidase. We show here that the predominance of subunit Va stems in part from the differential response of the two genes to the presence of molecular oxygen. Our results indicate that during aerobic growth, COX5a levels were high, while COX5b levels were low. Anaerobically, the pattern was reversed; COX5a levels dropped sevenfold, while those of COX5b were elevated sevenfold. Oxygen appeared to act at the level of transcription through heme, since the addition of heme restored an aerobic pattern of transcription to anaerobically grown cells and the effect of anaerobiosis on COX5 transcription was reproduced in strains containing a mutation in the heme-biosynthetic pathway (hem1). In conjunction with the oxygen-heme response, we determined that the product of the ROX1 gene, a trans-acting regulator of several yeast genes controlled by oxygen, is also involved in COX5 expression. These results, as well as our observation that COX5b expression varied significantly in certain yeast strains, indicate that the COX5 genes undergo a complex pattern of regulation. This regulation, especially the increase in COX5b levels anaerobically, may reflect an attempt to modulate the activity of a key respiratory enzyme in response to varying environmental conditions. The results presented here, as well as those from other laboratories, suggest that the induction or derepression of certain metabolic enzymes during anaerobiosis may be a common and important physiological response in yeast cells.

Aerobiosis↗
PubMed1989

Cloning and expression of ovine placental lactogen.

Ovine placental lactogen (oPL) is active in a wide range of GH and PRL assays, a property that it shares with human GH (hGH). In addition, oPL is one of a small number of hormones that bind the human GH receptor with high affinity. In order to compare the sequence of oPL to the sequences of other members of the GH family, full-length cDNA clones have been isolated. These clones predict that the full sequence of oPL contains 198 amino acids preceded by a 38 amino acid signal sequence. The mature oPL sequence includes six cysteine and two tryptophan residues and shows substantially more identity to bovine PL (67%) and oPL (49%) than to mouse (31%) or human (25%) PL or to oGH (28%) or (26%) hGH. Like the natural hormone, oPL expressed in mammalian tissue cells binds with high affinity to a soluble form of the recombinant hGH receptor. Thus, oPL binds to the human receptor in spite of having a sequence that is considerably divergent from hGH. Interestingly, the sequence of oPL differs from hGH at most of the amino acids recently found by mutagenesis studies to be important residues in the binding of hGH to the human receptor.

Amino Acid Sequence↗
PubMed1989

Bleeding patterns and acceptability among Norplant users in Singapore.

Norplant contraceptive implants are silastic implants containing levonorgestrel. This study describes our experience with 100 acceptors of NORPLANT implants in Singapore. No pregnancies occurred during the first year of use. The majority found the method's ease of use to be the most attractive feature. Disruption of menstrual rhythm appeared to be the least liked feature. However the incidence of these menstrual irregularities appeared to diminish with time. Implant users have tolerated this early disruption of their menstrual rhythm well and the continuation rate at the end of the year was 97%. Thus it appears that Norplant is a safe, effective and acceptable method of contraception.

Adolescent↗
PubMed1989

Interaction of EDTA with tributyltin induced cellular toxicity.

Tributyltin inhibited the growth of cells in concentration dependent manner. The inhibitory effect of tributyltin on E. coli was enhanced in the presence of metal ion chelator, EDTA. This was due to EDTA induced increase of permeability of bacterial cell envelope to tributyltin. In case of EDTA treated cells the rate of uptake of tributyltin was more pronounced as compared to control.

Drug Interactions↗
PubMed1989

Colonic anastomosis in calves: an experimental study.

Colonic anastomosis was conducted in 12 calves divided equally into four groups. Four suture patterns, viz. single inversion (continuous Connell), double inversion (two rows of continuous Cushing), single eversion (continuous everted mattress), double eversion (single eversion reinforced with simple continuous) were used. In each animal, anastomosis of the same technique was performed at four places. Each technique was evaluated in terms of clinical and gross observations, lumen stenosis and bursting pressure. Observations were made on the 7th, 14th and 28th day after anastomosis. None of the anastomotic techniques showed any untoward incident during the 28 days of postoperative study. Stricture formation at the site of anastomosis was minimal with the single inversion technique whereas it was maximum with the single eversion technique. Pressure for disruption of intestinal segments was higher after inversion than eversion techniques. It was concluded that the one-layer inversion anastomosis technique proved to be the best among the four techniques because (i) of its reduced incidence of adhesions; (ii) it maintains adequate lumen diameter; (iii) it withstands maximum pressure. The double layer inversion technique was conceded to be the second best choice for colonic anastomosis followed by the double eversion and single eversion techniques.

Anastomosis, Surgical↗
PubMed1989

Gall bladder disease: an analytical report of 250 cases.

Two hundred and fifty cases of biliary tract disease were studied as regards case history, physical and laboratory investigations, surgery and follow-up. It was found that females especially multipara were frequently affected; majority of cases were in 3rd to 5th decade of their life, rise in age showing decline in incidence. Majority of cases (82.4%) were vegetarians and had used vegetable fats (oriental diet). Most of the cases (98.8%) belonged to middle and poor class and were lean and thin. Pain in the right upper quadrant of the anterior abdominal wall had been the commonest symptom, in about half the cases it got aggravated by fatty meals. A mass was felt in the right hypochondrium in 29.6% and Murphy's sign was positive in 55.5% of cases. Radio-opaque calculi were present in 8% of cases, in another 10.8% the calculi were demonstrated by oral cholecystography, radiography could detect calculi in 47 (25.4%) cases and its overall diagnostic success rate has been low (56.8%). Ultrasonography proved more valuable tool for diagnosis; bile culture was positive in 8.8% of cases only for Esch coli, proteus, klebsiella, staphylococci or paracolon. Right subcostal incision gave the best results. Chronic cholecystitis with cholelithiasis (74%) was more common than acalculus cholecystitis (26%), incidence of carcinoma was 2.8%, and in 5 out of 7 cases malignancy was associated with cholelithiasis. Early diagnosis and cholecystectomy for gallstones can prevent malignancy. Surgery on the whole proved beneficial and it can be more rewarding if pre-operatively other causes of dyspepsia are either excluded or confirmed. Excluding cases of malignancy, the mortality has been quite low and thus acceptable.

Adolescent↗
PubMed1989

Balance in family planning.

Family planning has been so effective in Singapore that a risk exists of there being too few young people to sustain the country's economy in the twenty-first century. Relaxation of birth control policies and immigration laws offers hope that this problem will be averted.

Family Planning Services↗
PubMed1989

Village scale trial of deltamethrin against mosquitoes.

A village scale trial of Deltamethrin (K-othrin), formulated as a 2.5 per cent wettable powder and applied as a residual spray at a dosage of 25 mg/m2, was carried out against both anopheline and culicine mosquitoes, in Vikas Nagar village, Loni PHC, Distt. Ghaziabad (U.P.) in the month of August, 1985. Deltamethrin was found to be effective in reducing the overall vector population for about 10 to 12 weeks. Contact bio-assays also indicated that the insecticide has a residual life of about 12 weeks both on mud and cement plastered surfaces. No mortality was observed in bioassays against airborne effect of the insecticide sprayed on the walls. Twenty-four hour survival rate of the vector population was observed to be below 50 per cent upto 8 to 10 weeks. Observations indicated excito-repellent effect on mosquitoes forcing exodus from treated areas.

Animals↗
PubMed1989

Ultrasonography in non-cirrhotic portal hypertension: correlation with splenoportography.

Real time sonography followed by splenoportography was performed in 38 cases with non-cirrhotic portal hypertension. Eleven of these cases, in whom porto-systemic shunt surgery was done, were also evaluated by real time sonography post-operatively. The ultrasound findings correlated well in 37 cases (98%) with splenoportography. All the post-operative cases also revealed a patent portosystemic shunt on sonography. Ultrasonography, a valuable, non-invasive, initial investigation of portal hypertension, may thus be used as the only investigation to distinguish intra- from extra-hepatic obstruction and to evaluate patency of surgically created porto-systemic shunts. Invasive portography may be performed only if surgical treatment is anticipated.

Adolescent↗
PubMed1989

Effect of tributyltin on Escherichia coli: role of modifying factors.

The effects of inorganic and organic tin compounds and various factors affecting the toxicity of the latter to Escherichia coli were studied. In comparison to stannous chloride, tributyltin chloride (TBTC) was more inhibitory to the growth of the test organism; this may be due to its greater liposolubility and ready absorption through the bacterial membrane. The toxicity of TBTC to E. coli was modulated by various factors, such as pH, sulfate and chloride ions, and the presence of glucose, succinate, and reducing agents like cysteine and dithiothreitol (DTT). TBTC was more toxic to cells in minimal than in complex media. Similarly, this compound was more inhibitory to the growth of E. coli at acid pH than at basic pH. Succinate in contrast to glucose, when used as a carbon source, made the bacterium more sensitive to TBTC. Cysteine and DTT (both at a final concentration of 0.5 mM) partially protected the cells against the inhibitory effect of this agent.

Chlorides↗