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Biomedical subjects

N Kumar

Publications and source records attributed to N Kumar.

At least 253 records · Page 14Linked to original sources
PubMed1993

7 alpha-methyl-nortestosterone (MENT): the optimal androgen for male contraception.

UNLABELLED: Many methods of contraception involve the use of drugs that affect the secretion of hormones essential for reproduction. Oestrogens and progestins have been used for contraction in women as inhibitors of gonadotrophin secretion and ovulation. Similarly, androgens must be used in methods of fertility control for men that block gonadotrophin secretion. Androgen supplementation currently involves large, frequent doses of testosterone esters that are associated with wide fluctuations of plasma testosterone levels. Hence, there is a need for an androgen preparation that provides appropriate, continuous replacement doses over long periods. To achieve this goal, 7 alpha-methyl-19-nortestosterone (MENT), a synthetic androgen that is considerably more potent than testosterone, is suitable. As a consequence, it is feasible to administer this androgen as a substitute for testosterone for 1 year by subdermal implants. Another important feature of MENT is that it does not undergo 5 alpha- reduction in prostate as does testosterone. As a consequence, a dose of MENT sufficient to maintain normal muscle mass and gonadotrophin secretion will not hyperstimulate the prostate because its action in this organ is not amplified as is that of testosterone. Thus, MENT can be administered to men with the assurance that it will be less prone to cause diseases of the prostate than testosterone. CONCLUSIONS: (i) MENT is the first androgen that has a health benefit compared to testosterone; (ii) MENT will be promoted as one component of a two-implant system for male contraception, the other component being an implant that will release an LHRH analogue; (iii) MENT has potential uses in patients with a variety of disorders, including hypogonadism, prostatic hyperplasia and muscle wasting.

Animals↗
PubMed1993

Simulating the fiscal and distributional impacts of Medicaid eligibility reforms.

About 43 percent of nursing home costs are paid by Medicaid for the poor and for those who spend-down assets to qualify for Medicaid. We estimate the costs and distributional impacts of changes in the Medicaid asset test and the effect on the number of people spending down to Medicaid eligibility levels. Increasing asset thresholds from $2,00 to $12,000 would cost less than $4 billion, reduce spend-down rates, and increase the proportion of people eligible for Medicaid on admission to a nursing home. Even after such a change, about 80 percent of Medicaid benefits accrue to individuals with incomes less than $10,000.

Aged↗
PubMed1993

Polymyositis--a review and follow up study of 24 cases.

Twenty-four cases of polymyositis, 3 (12.5%) of them Dermatomyositis, have been treated and followed up for over 12 years. Majority (75%) were males. Inflammatory lesion was the cause in 18 (75%), collagen disease in 4 (16.7%) and malignancy in 2 (8.35%). Presenting features were fever (100%), proximal muscle weakness (95.8%) and tenderness (54.2%), facial and respiratory muscle weakness (4.2%). Raised CPK and transaminases, electromyogram abnormality and positive muscle biopsy were recorded in all. All were treated with steroids. Complication/associations noted were arthalgia (25%), dysphagia (20.6%), peripheral neuritis (8.35%), diabetes mellitus (4.2%), pulmonary fibrosis (4.2%) and malabsorption (4.2%). Fourteen cases (58%), all of inflammatory aetiology, recovered completely. Seven cases (29.2%) developed permanent atrophy of affected muscles. Cases with collagen disease and malignancy fared worse and deteriorated because of the primary disease.

Adult↗
PubMed1993

New prosthetic ring for aortic valve annuloplasty.

Aortic valve repair is recently receiving more attention. To broaden the indications for this procedure a prosthetic annuloplasty ring has been developed and tested in animals. Thirty-two sheep underwent implantation of such a ring in the pulmonary (14) and aortic (18) positions. In the 12 survivors followed for a maximum of 200 days the ring was found epithelialized and free from thrombus. One ring was dehiscent; no haemolysis was detected. It is concluded that a small clinical study is warranted.

Animals↗
PubMed1993

The challenge of valve surgery in a developing population.

Between August 1988 and October 1992, 1,052 patients underwent 1,522 valve procedures in our institution. Their mean age was 32.69 years (range 1-90). The etiology was rheumatic in 724 (68.8%), congenital in 120 (11.4%), degenerative in 99 (9.4%), infective in 58 (5.5%) and ischemic in 17 (1.6%). The mean preoperative functional class (NYHA) was 2.95 and 780 (74.1%) were in sinus rhythm. Repair was possible in 885 (58.1%) valves. The rate of repair versus replacement was 94.5% for the tricuspid, 56.2% for the mitral and 43.6% for the aortic valve. The total hospital mortality was 4.18%. For isolated mitral surgery it was 2.94%, for isolated aortic 4.12% and for isolated tricuspid 15%. Double valve surgery carried a mortality of 3% and triple valve surgery 13%. Hospital mortality for isolated mitral and isolated aortic surgery was lower for repair than for replacement (1.5% vs. 5% and 0 vs. 6.8%). The follow-up was 94.65% complete. The total incidence of embolic events was 2.93% with an actuarial freedom at 48 months of 92.71 +/- 5.35% for repair, 88.22 +/- 6.26% for replacement and 90.31 +/- 5.65% for patients with repair and replacement. Late mortality was 4.5%. The actuarial survival excluding hospital deaths was 94.89 +/- 2.10% for repair, 86.84 +/- 2.84% for replacement and 91.33 +/- 2.73% for the mixed group. The reoperation rate was higher for repair (13%) than for replacement (0.1%). This rate was highest for the rheumatic mitral patients with an age below 20 years (25.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

The Ross procedure in a young rheumatic population: early clinical and echocardiographic profile.

The use of pulmonary autografts for aortic valve replacement is nearing its third decade. It is showing promise as a permanent aortic valve with its ability to grow with age. We report our experience of 45 patients with a mean age of 16.89 years over a three year period. Rheumatic heart disease was the cause of aortic valve dysfunction in 38 (84.4%) patients. Sixteen (35.5%) patients also underwent mitral valve repair. Echocardiographic examination revealed early reduction of aortic regurgitation and left ventricular dimensions, which remained stable in the short follow up period. There were no early or late deaths. One patient required reoperation for a regurgitant pulmonary autograft at two years. We conclude that pulmonary autograft transplantation to the aortic root seems to offer a near permanent solution in a young population affected by rheumatic valve disease.

Adolescent↗
PubMed1993

Surgery for organic rheumatic disease of the tricuspid valve.

The paucity of reports on the incidence and management of organic involvement of the tricuspid valve in rheumatic disease led us to carry out this retrospective study. Over a four and a half year period, of the 1052 patients undergoing valve surgery at our institution, 253 (24.05%) required tricuspid surgery. Organic involvement was noted in 115 (45.45%) of these patients. Definitive preoperative diagnosis was feasible by echocardiogram in only 48 (41.73%). Tricuspid regurgitation was present in all patients while detectable stenosis was present in 48 (41.7%). Annular dilatation was seen in 52 (45.2%). Primary repair was possible in 107 patients (93.0%). The reduction in tricuspid regurgitation remained stable at the last follow up in all but seven patients. Nine patients underwent reoperation in this study for failure of left-sided valve repairs, of which five needed reoperation on the tricuspid valve. All the five reoperated tricuspid valves had had dilated annuli at primary surgery. The presence or absence of annular dilatation did not cause any significant difference in early or late mortality. The presence of annular dilatation in the presence of left-sided valve lesions superimposed on organically involved tricuspid valves evokes the possibility of the presence of an organo-functional disease.

Adolescent↗
PubMed1993

Vanishing De Vega annuloplasty for functional tricuspid regurgitation.

Annuloplasty is performed for significant functional tricuspid regurgitation even if it is presumed that in some cases the regurgitation will regress spontaneously after correction of the left-sided lesion. In an attempt to avoid the drawbacks of a permanent annuloplasty, we used a reabsorbable De Vega annuloplasty in a selected group of patients. Of 73 patients with functional tricuspid regurgitation operated on between May 1989 and May 1991, 25 with pulmonary arteriolar resistance below 400 dyne.sec.cm-5 underwent a De Vega annuloplasty with 2-0 polydioxanone suture. The diagnosis of significant functional tricuspid regurgitation (mean 2.74 +/- 1.05) was established by transthoracic color Doppler echocardiography in all patients. The degree of functional tricuspid regurgitation and pulmonary arteriolar resistance were measured with the patients anesthetized. In 16 patients the regurgitation remained severe (3+ to 4+) and in 9 it was moderate (2+). Twenty-three patients had mitral (12 repairs, 11 replacements) and 9 had aortic (4 repairs, 5 replacements) valve operations. The immediate postbypass residual functional tricuspid regurgitation was 0 to 1+ in 23 and 0 in 2. There was 1 (4%) operative death. The maximum follow-up period was 24 months (mean 13.9 months). There were 2 (8.3%) late deaths. Six patients underwent reoperation because of mitral dysfunction. Four of them who were reoperated on between 2 and 5 weeks after the initial procedure showed no recurrence of functional tricuspid regurgitation. The other 2, reoperated on at 5 and 10 months after the first operation, had recurrence of functional tricuspid regurgitation. Visual inspection of these two tricuspid valves showed a dilated anulus with otherwise normal valves. All surviving patients are in New York Heart Association functional class I or II without significant functional tricuspid regurgitation (mean 0.78 +/- 0.56). We concluded that functional tricuspid regurgitation in patients with low pulmonary arteriolar resistance can be adequately treated by a vanishing De Vega annuloplasty, which will stent the tricuspid anulus for about 4 months.

Adolescent↗
PubMed1993

Comparative bioavailability of two enteric-coated capsules of omeprazole in healthy volunteers.

A comparative bioavailability study was carried out on two enteric-coated capsules (20 mg each) of omeprazole (omeprazole, Alembic: "A" and Losec, Astra, England: "B"). The in-vitro dissolution of both products "A" and "B" met the prescribed USP standard. The bioavailability of single dose (20 mg) and multiple doses (20 mg once daily for 7 days) of both products "A" and "B" were carried out in eight healthy male volunteers in a crossover design. The rate and extent of bioavailability of omeprazole was higher in product "A" following a single oral dose, suggesting its therapeutic advantage over the product "B" in the prevention of acid aspiration during surgery. In multiple dose study, the two products were found bioequivalent as assessed by AUC0-infinity, Cmax, tmax and t1/2 elimination.

Adult↗
PubMed1992

Structure of RG-12561 dichloromethane solvate and a diastereomer.

(III): [4 alpha,6 beta(E)]-(+-)-6-(2-[2-(4-Fluoro-3-methylphenyl)- 4,4,6,6-tetramethyl-1-cyclohexen-1-yl]ethenyl)-4-hydroxytetrahy dro pyran-2-one (RG-12561) dichloromethane solvate, 2C24H31FO3.CH2-Cl2, Mr = 857.94, triclinic, Pl, a = 11.7413 (5), b = 13.0279 (5), c = 16.2332 (9) A, alpha = 99.456 (4), beta = 94.217 (4), gamma = 101.893 (4) degrees, V = 2381.9 (4) A3, Z = 4 [four molecules of (III)+two molecules of solvent per unit cell], Dx = 1.195 g cm-3, Cu K alpha, lambda = 1.54178 A, mu = 16.69 cm-1, F(000) = 912, T = 293 K, final R = 0.053, wR = 0.060 for 4031 reflections with I greater than 3 sigma(I). (IV): [4 beta,6 alpha(E)]-(+-)-6-(2-[2- (4-Fluoro-3-methylphenyl)-4,4,6,6-tetramethyl-1-cyclo-hexen-1-yl]e thenyl)-4- hydroxytetrahydropyran-2-one, C24H31FO3, Mr = 386.51, triclinic, Pl, a = 6.054 (2), b = 12.931 (2), c = 14.838 (3) A, alpha = 67.70 (2), beta = 85.75 (2), gamma = 82.85 (2) degrees, V = 1066.0 (8) A3, Z = 2, Dx = 1.203 g cm-3, Cu K alpha, lambda = 1.54178 A, mu = 6.86 cm-1, F(000) = 414, T = 293 K, final R = 0.073, wR = 0.081 for 1588 reflections with I greater than 3 sigma(I). (III) is a potent HMG-CoA reductase inhibitor and has the potential to function as a superior hypocholesterolemic agent; (IV) lacks this activity. (III) and (IV) have different conformations and molecular-model calculations suggest that crystal-packing effects are primarily responsible for the overall conformation of (IV). The principal intermolecular contacts are hydrogen bonds of the type O-H...O = C.

Anticholesteremic Agents↗
PubMed1992

New surgical technique for type B aortic interruption.

Restoring continuity of the aortic arch in aortic interruption continues to be a problem in terms of both surgical technique and long-term results. We report here a surgical technique using the left subclavian artery along with an aberrant right subclavian artery to form a conduit in a patient with type B interruption, to reestablish aortic continuity.

Aorta, Thoracic↗
PubMed1992

Sleep deprivation in human males and its effect on SCE rates in chromosomes--a preliminary study.

The present preliminary study on 5 healthy volunteers deprived of sleep for a day showed a considerable increase in sister-chromatid exchange (SCE) rate in the chromosomes after sleep deprivation. Although the rate of increase varied between the studied subjects, interestingly the 5% plasma from a volunteer with a statistically significant increase after sleep deprivation, when supplemented to cell cultures from an age-matched normal subject, induced high SCEs. This suggests the presence/absence of some factor(s) in plasma samples of subjects showing high SCEs after sleep deprivation, playing a role in the induction of high SCEs in normal cells exposed to the samples in vitro. The present study also suggests that there could be categories which may or may not respond to sleep deprivation with high SCE induction and their plasma supplemented to normal cell culture in turn may or may not induce high SCEs. Nevertheless, the pathophysiological role of high SCEs induced by sleep deprivation in some cases remains intriguing and unresolved and needs further extensive study.

Adult↗
PubMed1992

Further characterization of interactions between gamete surface antigens of Plasmodium falciparum.

Target antigens of malaria transmission blocking immunity include a complex of 3 gamete surface proteins of 230-kDa and 48/45-kDa glycoproteins. Previous studies have shown that epitopes recognized by blocking antibodies are conformational (reduction sensitive) in nature. Studies were conducted to characterize the interactions between the target antigens and role of disulfide groups in the formation of the complex. Treatment of detergent extracts of gametes with chaotropic agents and extremes of pH resulted in dissociation of the complex. The interaction between the 3 proteins was also perturbed when the extract was incubated in the presence of antibodies against the 230-kDa protein but not against the 48/45-kDa doublet. Chemical modifications of disulfide and sulfhydryl groups in the target antigens, otherwise inaccessible either in the total extract or after phase separation in Triton X-114, required prior denaturation of antigens.

Animals↗