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Biomedical subjects

M Kumar

Publications and source records attributed to M Kumar.

At least 415 records · Page 23Linked to original sources
PubMedDate not supplied

Identification of vasopressor constituents of amniotic fluid in pregnancy toxaemia.

The vasopressor activity of human amniotic fluid was assessed in 46 primigravidas during the third trimester of pregnancy. The subjects included 20 normal and 26 cases of pregnancy toxaemia. For identification of the vasopressor activity of the amniotic fluid, blood pressure measurements were made in the intact rat, and the smooth muscle contraction of the rat ascending colon preparation was determined in vitro. The samples of amniotic fluid showing vasopressor activity were lyophilized and subjected to gel filtration using Sephadex G-100. The various fractions thus obtained were monitored at 280 nm and the pressor activity was re-estimated. It was observed that most of the pressor activity of the amniotic fluid of the toxaemic patients was capable of causing contraction of the rat colon as well as a significant rise in the systolic blood pressure of the intact rat. Furthermore, this activity was found to be heat-labile and was completely blocked by cinnarizine. Fractionation of the amniotic fluid showing vasopressor activity by gel filtration further substantiated the findings reported above. On the basis of these results it was concluded that the pressor activity of the amniotic fluid was due to the presence of an angiotensin II-like substance. Its concentration was found to be higher in the toxaemic group than in normotensive subjects.

Amniotic Fluid↗
PubMedDate not supplied

In vivo thrombolysis. An experimental model in rhesus monkeys.

An experimental model of diffuse thromboembolism in the intrarenal circulation of the rhesus monkey was produced by intra-arterial injection of homogenised, homologous [125-I]fibrin. A sequential study of thromolysis was carried out using the conventional method of determining the thromboembolic index in the arteries of both kidneys together with radioautography and counting of radioactivity in the renal homogenate. Quantitative estimation of radioactivity in the renal homogenate, as well as radioautography of kidney sections provided more accurate and sensititve indices of the thrombolytic process than the conventional thrombembolic index. Studies on blood coagulation and fibrinolysis revealed only mild changes corresponding to the dynamics of thrombolysis in vivo. It was further noted that the thrombolytic mechanism in rhesus monkeys is very active and can clear thromboemboli from the intrarenal arteries within 8 days of their induction

Animals↗
PubMedDate not supplied

Treatment of visceral leishmaniasis (kala-azar) with aminosidine (= paromomycin)-antimonial combinations, a pilot study in Bihar, India.

A 20 d drug regimen of aminosidine (= paromomycin) at 12 mg/kg/d in combination with sodium stibogluconate at 20 mg/kg/d proved efficacious and well-tolerated in patients with visceral leishmaniasis in the State of Bihar, India. Eighteen of 22 evaluable patients achieved an ultimate cure. The remaining 4 patients, although not cleared of parasites, had their parasite grade reduced and also improved clinically. This confirms prior findings in Kenyan patients with kala-azar, and indicates that this regimen is a valid alternative to antimonial compounds alone in the State of Bihar, where cases of kala-azar not responding to antimonial drugs and intolerant of pentamidine are increasingly recorded.

Adolescent↗
PubMedDate not supplied

History of gestational diabetes, insulin resistance and coronary risk.

The purpose of this study was to examine characteristics associated with the insulin metabolic syndrome, including insulin resistance, abnormal glucose tolerance, dyslipidemia, obesity, and elevated blood pressure, among women who have experienced gestational diabetes. 39 nondiabetic, young (20-42 years), postpartum (3-18 months) white women were recruited from obstetrical clinics. Twenty-one women had a history of gestational diabetes; 18 had uncomplicated pregnancies. Multivariate analyses revealed a significant difference between groups in insulin resistance (M, measured by euglycemic clamp) and insulin levels (from an oral glucose tolerance test), with insulin resistance showing a statistically stronger difference than insulin levels. Groups also differed significantly when compared on a set of variables associated with insulin metabolic syndrome: glucose tolerance, triglycerides, blood pressure, and body-mass index. Using insulin resistance as a covariate eliminated these group differences, suggesting that insulin resistance is the key factor underlying insulin metabolic syndrome. The higher risk of later developing type 2 diabetes and hypertension in women who have a history of gestational diabetes is explicable by their poorer profile on variables associated with insulin metabolic syndrome, and appears to be attributable to insulin resistance. Thus, insulin resistance appears to distinguish young women at risk for cardiovascular disease.

Adult↗
PubMedDate not supplied

Prospects of riboflavin carrier protein (RCP) as an antifertility vaccine in male and female mammals.

Riboflavin carrier protein (RCP) is obligatorily involved in yolk deposition of the vitamin, riboflavin, in the developing oocyte of the hen. The production of this protein is inducible by oestrogen. It is evolutionarily conserved in terms of its physicochemical, immunological and functional characteristics. It is the prime mediator of vitamin supply to the developing fetus in mammals, including primates. Passive immunoneutralization of the protein terminates pregnancy in rats. Active immunization of rats and bonnet monkeys with avian RCP prevents pregnancy without causing any adverse physiological effects of the mother in terms of her vitamin status, reproductive cycles or reproductive-endocrine profile. Denatured, linearized RCP is more effective in eliciting neutralizing antibodies capable of interfering with embryonic viability either before or during peri-implantation stages. Two defined stretches of sequential epitopes, one located at the N-terminus and the other at the C-terminus of the protein have been identified. Active immunization with either of these epitopes conjugated with diphtheria toxoid curtails pregnancy in rats and monkeys. Immunohistochemical localization of RCP on ovulated oocytes and early embryos shows that the antibodies cause degeneration only of early embryos. RCP is produced intra-testicularly and becomes localized on acrosomal surface of mammalian spermatozoa. Active immunization of male rats and monkeys with denatured RCP markedly reduces fertility by impairing the fertilizing potential of spermatozoa. These findings suggest that RCP, or its defined fragments, could be a novel, first generation vaccine for regulating fertility in both the sexes.

Amino Acid Sequence↗
PubMedDate not supplied

Emotional repression, stress disclosure responses, and Epstein-Barr viral capsid antigen titers.

Based on the theory of psychosomatic inhibition, we hypothesized that subjects who abstained from disclosing emotional material on a laboratory task would have poorer control of latent Epstein-Barr virus (as evidenced by high titers for the viral capsid antigen), and similarly, those subjects with psychometrically derived repressive interpersonal styles would show the highest Epstein-Barr viral capsid antigen titers (EBV-VCA). Eighty first-year undergraduates completed a personality inventory and were asked to write an essay/letter for 30 minutes about a stressful event that had happened in their life. Blood was collected from each subject immediately after writing. Essays were scored for degree of emotional disclosure according to the ratio of emotional-to-total words used. Degree of disclosure was found to be associated with impaired control of latent EBV (high antibody titers to the EBV-VCA) controlling for medication use, recent sleep loss, physical activity, lean body mass, caloric intake, and alcohol and recreational drug use. Further, individual differences in interpersonal style (characterized by emotional suppression) related to this immunologic marker in a similar fashion, and these two factors interacted in determining EBV-VCA titers. That is, Repressors who were either high or low disclosers had high levels of antibody titer to EBV-VCA, whereas only those Sensitizers who did not disclose had high antibody titers to EBV-VCA. In addition to supporting the hypothesis that emotional repression is associated with some aspects of host-virus interaction, the present findings highlight the importance of obtaining behavioral and psychometric assessments in psychoimmunologic investigations of this abstract affective construct (i.e., repression).

Adolescent↗
PubMedDate not supplied

Plasma pyridoxine deficiency is related to increased psychological distress in recently bereaved homosexual men.

OBJECTIVE: Previous research has demonstrated that a theoretical model including measures of life stressors, social support, and coping style significantly predicts psychological distress. This study tested plasma pyridoxine (vitamin B6) deficiency status as a predictor of overall psychological distress and specific mood states in this model, controlling for HIV-1 serostatus. METHOD: Subjects included HIV-1+ (N = 76) and HIV-1- (N = 58) recently bereaved homosexual men. At baseline, subjects completed a battery of psychosocial questionnaires, together with a physical examination and venipuncture. The Profile of Mood States (POMS) provided measures of overall psychological distress as well as specific mood states. Pyridoxine deficiency status (a categorical measure of deficient vs. adequate status) was determined with a bioassay of erythrocyte aspartate aminotransferase activity. RESULTS: Pyridoxine deficiency was a significant predictor of increased overall psychological distress in this model, controlling for life stressors, social support, coping style, and HIV-1 serostatus. In post hoc analyses of specific mood state effects, pyridoxine deficiency status was significantly associated with increases in depressed, fatigued, and confused mood levels, but not with those of anxiety, anger, or vigor. DISCUSSION: These findings suggest that adequate pyridoxine status may be necessary to avert psychological distress in the setting of bereavement. Inasmuch as pyridoxine is a cofactor for 5-hydroxytryptophan decarboxylase--an enzyme in the biosynthesis pathway of serotonin--serotonin level in the brain is implicated as the mediating factor.

Adaptation, Psychological↗