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Biomedical subjects

N Kumar

Publications and source records attributed to N Kumar.

At least 55 records · Page 3Linked to original sources
PubMed1994

Thrombotic obstruction of bileaflet valves: surgical management and fiberoptic thrombectomy.

Three patients underwent emergency operation for thrombotic obstruction of a bileaflet mechanical prosthesis (two St. Jude and one Duromedics) in the mitral position. The three valves were successfully thromboectomized with return to normal function. In 2 patients removal of the thrombus at the valve hinges was assisted by the use of a flexible fiberoptic choledochoscope. All 3 patients remain well 2 years after the procedure, maintained on a regimen of warfarin and dipyridamole.

Dipyridamole↗
PubMed1994

Aromatization of 7 alpha-methyl-19-nortestosterone by human placental microsomes in vitro.

Part of the biological effects of testosterone (T) are mediated by its enzymatic reduction to 5 alpha-dihydrotestosterone (DHT) or aromatization to estradiol (E2). 7 alpha-Methyl-19-nortestosterone (MENT) is a synthetic androgen that is considerably more potent than T. Previous studies have shown that MENT is not 5 alpha-reduced. The studies reported here were undertaken to determine whether MENT undergoes enzymatic aromatization in vitro. Human placental microsomes were used as the source of the aromatase. Radioactive or nonradioactive T or MENT was incubated with the microsomes in the presence of NADPH and the metabolites extracted out with ethyl ether. Following evaporation of ether, the residue was dissolved in benzene-petroleum ether and extracted with 0.4 N NaOH which selectively removes phenolic metabolites of the androgens. When either radioactive T or MENT was incubated with the aromatase in the presence of NADPH, there was a 20-fold increase in the amount of radioactivity extracted with NaOH. In contrast, if the incubation was carried out in the absence of NADPH or in the presence of R76713, an aromatase inhibitor, most of the radioactivity remained in the benzene-petroleum ether phase. To further identify the enzymatic reaction products, thin layer chromatography (TLC) was performed. The Rf value for MENT was 0.22 while that of the major reaction product was 0.34, which corresponded with the RF value of the estrogen, 7 alpha-methyl-estradiol (MeE2). This was further verified by using a second solvent system for the chromatographic separation. In an effort to ascertain whether the metabolites bind to estrogen receptors (ER), rat uterine cytosol was used. NaOH extracts of medium following incubation of nonradioactive MENT with microsomes showed competitive inhibition of [3H]E2 binding to rat uterine ER. Furthermore, after [3H]MENT was incubated with microsomes, the radioactive metabolite extracted in NaOH showed specific binding to the ER which could readily be displaced with E2 or MeE2. These results indicate that like T, MENT undergoes enzymatic aromatization.

Aromatase↗
PubMed1994

7 alpha-Methyl-19-nortestosterone: an ideal androgen for replacement therapy.

MENT is a synthetic androgen which cannot be 5 alpha-reduced. Therefore, relative to T, its stimulatory action on the prostate is lower than that on the muscle and pituitary. Like T, MENT undergoes enzymatic aromatization to an estrogen. We conclude that the use of MENT instead of T for androgen replacement therapy could have health-promoting effects by reducing the occurrence of prostate disease.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1994

Post lumbar puncture discitis and vertebral collapse.

Discitis and vertebral collapse are rare but serious complications of lumbar puncture. Clinical profile, management and course of post lumbar puncture discitis in five patients is presented. Such a complication should be kept in mind whenever any invasive procedure is carried out on the spine.

Adult↗
PubMed1994

Lipoprotein lipids and the prevalence of hyperlipidaemia in rural India.

BACKGROUND: The prevalence of hyperlipidaemias has been inadequately studied in rural populations of developing countries. No significant data exist on the population levels of serum cholesterol, cholesterol subclasses or triglycerides in these countries. METHODS: We studied fasting blood samples of 300 apparently healthy adults (202 men and 98 women, age range 20-73 years) randomly selected from a larger sample of 3148 individuals during a comprehensive cardiovascular risk-factor survey in Rajasthan, India. Levels of serum total cholesterol, its subfractions [low-density-lipoprotein (LDL) cholesterol, very-low-density-lipoprotein cholesterol and high-density-lipoprotein (HDL) cholesterol] and triglycerides were measured and correlated with age and anthropometric data. RESULTS: The mean +/- SD serum total-cholesterol levels were 4.39 +/- 1.0 mmol/l in men and 4.37 +/- 1.0 mmol/l in women, the mean LDL-cholesterol levels 2.51 +/- 1.0 mmol/l in men and 2.62 +/- 0.9 mmol/l in women, the mean HDL-cholesterol levels 1.15 +/- 0.4 mmol/l in both mean and women and the mean fasting serum triglyceride levels 1.63 +/- 0.6 mmol/l in men and 1.48 +/- 0.7 mmol/l in women. Age correlated positively with total-cholesterol, LDL-cholesterol, HDL-cholesterol and triglyceride levels in both men and women. Levels of the cholesterol subtypes did not differ between the sexes (P > 0.01), although triglyceride levels were significantly higher in men (P < 0.01). Lipoprotein lipids did not correlate significantly with height, weight, body-mass index or waist:hip ratio. When classified according to the recommendations of the US National Cholesterol Education Program for the determination of the prevalence of hyperlipidaemia, 43 individuals (14.3%; men 14.4% and women 14.3%) had borderline high cholesterol levels (5.20-6.18 mmol/l) and 24 (8%; men 7.9% and women 8.2%) had high cholesterol levels (> or = 6.21 mmol/l). Forty-five participants (15%) had borderline high LDL-cholesterol levels (3.36-4.11 mmol/l) and 20 (6.7%) had high LDL-cholesterol levels (> or = 4.14 mmol/l); low HDL-cholesterol levels (< 0.9 mmol/L) were found in 89 (29.7%). Eighteen participants (6%) had mild hypertriglyceridaemia (2.82-5.64 mmol/l) and two (0.7%) had severe hypertriglyceridaemia (> 5.64 mmol/l). CONCLUSION: Total-cholesterol and LDL-cholesterol levels are low in a rural Indian population, although an atherogenic lipid profile is present in a significant proportion.

Adult↗
PubMed1994

Long-term care insurance and Medicaid.

Depending on length-of-stay, somewhere between 29 percent and 38 percent of long-term care insurance purchasers who use nursing homes would qualify for Medicaid payments if they did not own a policy. This is equivalent to between 13 percent and 17 percent of all policyholders. Owning such a policy would, however, reduce spend-down rates among policyholders by 39 percent. Thus, in the presence of long-term care insurance, only 8 to 10 percent of all policyholders would receive Medicaid. Medicaid would spend between $6,492 and $14,179 (in 1990 dollars) on nursing home entrants with long-term care insurance policies--$14,437 to $29,698 if entrants did not have insurance. The ultimate impact on Medicaid expenditures is reduced, however, because many policyholders voluntarily let their policies lapse before entering nursing homes. If policies paid reduced benefits for voluntary lapses, then Medicaid could reap more significant fiscal savings.

Aged↗
PubMed1994

Pulmonary autograft for aortic valve replacement in rheumatic disease--an ideal solution?

The use of pulmonary autograft for aortic valve replacement (Ross procedure) offers an excellent option for the younger patient with its potential for growth and long term viability. We report our experiences of 61 patients with a mean age of 17.0 years undergoing Ross procedure over a four year period. Rheumatic disease was the cause of aortic valve disease in 48 (79.0%) patients. Mitral valve surgery was required in 18 (29.5%) patients. There was no hospital death, endocarditis or thromboembolism in the series. There was one late death from non-cardiac cause and three (4.9%) reoperations. Two of the reoperations were for progressive autograft regurgitation whilst the third was for mitral valve repair failure. Echocardiographic profiles of 37 of these patients followed beyond six months after surgery show a tendency towards progression of the autograft regurgitation. The long term effects of rheumatic disease on the transplanted valves remain to be evaluated.

Adolescent↗
PubMed1993

Expression of members of the heat-shock protein 70 family in the exoerythrocytic stages of Plasmodium berghei and Plasmodium falciparum.

Exoerythrocytic stages of Plasmodium berghei cultured in HepG2-A16 hepatoma cells and those of P. falciparum in human hepatocytes transplanted under the kidney capsule of CB-17/ICr scid/scid mice were used to evaluate expression of heat-shock-related stress proteins. Although undetectable in the sporozoites, the expression of proteins similar in sequence of a heat-shock protein of 70 kDa and a glucose-regulated protein of 78 kDa was markedly induced in the hepatic stages of malaria parasites. Expression of these proteins in the exoerythrocytic stages of the malaria parasite warrants a systematic evaluation of their potential role in eliciting cellular immune responses directed against infected hepatocytes.

Animals↗
PubMed1993

Nifedipine attenuates the hypertensive response to tracheal intubation in pregnancy-induced hypertension.

Thirty women with pregnancy-induced hypertension (PIH) scheduled for Caesarean section under general anaesthesia were studied to evaluate the efficacy of sublingual nifedipine in attenuating the pressor response to laryngoscopy and tracheal intubation. The patients were randomly given either the contents of a nifedipine capsule 10 mg or placebo sublingually 20 min before induction of anaesthesia. Blood pressure and heart rate were recorded at various time intervals. There was a decrease in mean arterial blood pressure (MAP) after pretreatment with nifedipine (P < 0.01). The increase in MAP during laryngoscopy and intubation was higher in the control group compared with nifedipine pretreatment group (P < 0.01). During laryngoscopy and intubation, MAP decreased by 3 mmHg in the nifedipine pretreatment group, while there was an increase of 14 mmHg in the control group. Heart rate increased in both the groups during the laryngoscopy and tracheal intubation (P < 0.01) but the increase was higher in the nifedipine group than in the control group (P < 0.05). Neonatal Apgar scores in both the groups were comparable. These results suggest that sublingual nifedipine is effective in attenuating the hypertensive response to laryngoscopy and intubation but not the tachycardiac response in parturients with PIH.

Administration, Sublingual↗