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Biomedical subjects

R Juneja

Publications and source records attributed to R Juneja.

At least 73 records · Page 4Linked to original sources
PubMed1993

Regulation of serotonin-induced calcium uptake in Spisula oocytes by tricyclic antidepressants.

The effect of tricyclic antidepressants on 5-hydroxytryptamine (serotonin or 5-HT)-induced maturation and Ca2+ uptake in Spisula oocytes was determined. The drugs at a concentration of 20 microM completely blocked germinal vesicle breakdown and 45Ca2+ uptake by Spisula oocytes. The order of effectiveness of the antidepressants were imipramine > desipramine > clomipramine. The present findings suggest that the action of tricyclic antidepressants is to regulate Ca2+ uptake into 5-HT-responsive cells.

Animals↗
PubMed1993

Inhibition of progesterone action by a factor in human follicular fluid.

A factor was found in human follicular fluid that blocked progesterone-stimulated net uptake of 45Ca2+ in human sperm and progesterone-induced maturation of Xenopus oocyte. The factor was partially purified by ultrafiltration through PM-10 membrane and gel filtration on Sephadex G-25 column. The active fraction is effective at a concentration of 200 micrograms/ml. The present findings suggest that hFF factor may regulate the metabolism of progesterone sensitive cells.

Animals↗
PubMed1992

Calcium transport and Ca(++)-ATPase activity in spermatozoal plasma membrane vesicles of nifedipine-administered guinea pigs.

Spermatozoal plasma membrane vesicles isolated from distal portion of the epididymis and vas deferens were found to contain Ca(++)-activated ATPase and calcium transport activities. Nifedipine was administered at two different doses (1.0 and 2.5 mg/kg b.w./day) and the effect was observed for both short- (4 week) and long-term (12 week) period. The cellular ionic calcium content and Ca(++)-ATPase activity were observed to be enhanced in the drug-treated animals. The recovery studies carried out after 4 and 6 weeks of withdrawal of the drug treatment exhibited partial to complete restoration of observed changes. The stimulatory rather than inhibitory effect of Nifedipine, a specific calcium channel blocker, on calcium uptake may suggest that voltage-sensitive calcium channels may be lacking in guinea pig spermatozoa. The stimulatory effect of the drug is speculated to be either by inhibition of Na(+)-Ca++ antiporter or G-protein activated agonistic effect or probably due to altered physicochemical properties of the drug-treated sperm plasma membranes.

5'-Nucleotidase↗
PubMed1992

Immunoassay for the determination of surfactant apoprotein (SP-A) in human amniotic fluid: comparison with other indices of assessing foetal lung maturity.

The concentration of the major surfactant-associated protein SP-A (28-36 kDa) was determined in 73 amniotic fluid samples obtained from normal (n = 40) and complicated (n = 33) pregnancies. Lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol (PG) levels were also determined in all the samples by one-dimensional step-wise thin-layer chromatography. An enzyme-linked immunosorbent assay was used to determine human lung surfactant apoprotein SP-A. The amount of SP-A in human amniotic fluid increased as a function of gestational age from 8 mg l-1 at 36 weeks to 11.75 mg l-1 at 40-41 weeks of gestation. There was a significant difference (p less than 0.01) in amniotic fluid SP-A concentration from female (9.93 +/- 0.60 micrograms ml-1) compared to male (9.10 +/- 0.52 micrograms ml-1) foetuses. In amniotic fluid samples obtained from a group of complicated pregnancies, SP-A levels were significantly lower than in the normal group when adjusted for gestational age and sex of the foetus (p less than 0.05).

Amniotic Fluid↗
PubMed1992

Interaction of pulmonary surfactant-associated protein (SP-A) with surfactant lipids.

A pulmonary surfactant-associated protein complex with components of 36, 32 and 28 kDa was isolated from human lung homogenates and reassembled with surfactant lipids prepared as small unilamellar liposomes. The role of divalent cations in the assembly of this recombinant lipoprotein complex was studied by monitoring the changes in turbidity, intrinsic tryptophanyl fluorescence and surface activity. The protein-facilitated lipid aggregation was promoted on addition of 5 to 20 mM Ca2+. Intrinsic fluorescence measurements on SP-A (28-36 kDa) indicated that the tryptophan side chains were in a relatively hydrophobic environment, that the wavelength of maximum fluorescence emission and also the relative fluorescence, were changed upon the binding of lipid. Tryptophanyl fluorescence of the lipoprotein assembly was quenched as indicated by a reduction in the effective Stern-Volmer constant. These results suggest that Ca2+ lipid-protein interactions are involved in the structure and function of extracellular lung surfactant assembly.

Adult↗
PubMed1992

Analysis of the major surfactant-associated proteins in human lung.

The protein component of human pulmonary surfactant was analysed. A purified surfactant preparation, after delipidation, was subjected to gel filtration on Sephadex G-200. The proteins present in the surfactant were categorised by means of SDS-polyacrylamide gel electrophoresis into serum and non-serum components. Molecular masses determination showed the presence of three sub-groups with molecular masses of 60-68 kDa, 28-36 kDa and 10-18 kDa, respectively. Antiserum generated against 28-36 kDa protein strongly reacted with the purified surfactant and amniotic fluid, while it did not show any cross reactivity with other groups of proteins and serum in a double diffusion immunoprecipitation assay. We propose that this protein is the major non-serum surfactant-associated protein present in human lung surfactant.

Adult↗
PubMed1990

Verapamil stimulates Ca(++)-uptake and Ca(++)-ATPase in plasma membrane vesicles of guinea pig spermatozoa.

Verapamil, a potent calcium channel blocker, was administered orally at three different doses to guinea pigs for both short- (4 weeks) and long-term (12 weeks) effects. The drug treatment stimulated Ca(++)-transport and Ca(++)-activated ATPase in isolated plasma membrane vesicles of guinea pig spermatozoa. Ca(++)-uptake studies exhibited partial to complete restoration of stimulated Ca(++)-transport during recovery period, whereas the CA(++)-activated ATPase system remained stimulated even after 4 and 6 weeks of withdrawal of the drug treatment. The lack of inhibitory effect of verapamil on Ca(++)-uptake ruled out the involvement of calcium channels in spermatozoal calcium uptake in guinea pigs. The stimulatory effect of the drug on CA(++)-uptake, on the other hand, might indicate the possible capability of this lipophilic compound to induce favourable changes in the lipid microenvironment of the membrane, wherein the integral membrane proteins operate.

Animals↗
PubMed1990

Effect of verapamil on different spermatozoal functions in guinea pigs--a preliminary study.

Verapamil, a calcium channel blocker, was administered orally using three different doses to guinea pigs. Both short-term (4 weeks) and long-term (12 weeks) effects of the drug were observed. The drug administration resulted in a marked decrease in sperm density, sperm motility and cellular energy content (ATP). Zona pellucida penetration by the sperm obtained from drug-treated animals was significantly lower when compared with sperm from normal animals. Histopathological findings exhibited partial arrest of spermatogenesis. Partial to complete recovery was observed after 4 and 6 weeks of withdrawal of the drug treatment.

Adenosine Triphosphate↗
PubMed1990

Sequential isolation and biochemical analysis of pulmonary surfactant from human lung homogenate.

Pulmonary surfactant was isolated from human lung homogenate after differential and sucrose density gradient centrifugation. Purification of the isolated material was ascertained by electron microscopy and alkaline phosphatase (AKP) specific activity. Elevated levels of phospholipid/protein ration and AKP specific activity were observed in the purified material when monitored at different stages of purification. Biochemical analysis of the isolated material showed that it consisted of 74.08% lipid, 19.06% protein and relatively smaller amounts of nucleic acids, sialic acid and hexoses. Phosphatidyl choline was the predominant phospholipid whereas triglycerides and cholesterol levels were high among neutral lipids. Gas liquid chromatography of the material showed palmitic acid (16:0) as the major saturated fatty acid. These findings indicated that a large scale isolation of surfactant might be possible and utilized for therapeutic treatment of neonatal respiratory distress syndrome.

Adult↗
PubMedDate not supplied

Percutaneous transvenous mitral commissurotomy in patients with severe mitral stenosis and acute rheumatic fever.

There is a concern that percutaneous transvenous mitral commissurotomy (PTMC) performed during acute rheumatic fever (ARF) may result in adverse outcomes. We performed a retrospective study at a tertiary care center. Ten patients (ages 8-12 years) with severe symptomatic mitral stenosis and ARF who underwent PTMC (ARF group) were compared with 10 controls with similar mitral valve area (MVA). The procedure was successful in all patients. The median MVA increased from 0.7 to 1.5 cm2 following PTMC in the ARF group and from 0.7 to 1.8 cm2 in the control group [p = not significant (NS)]. The median MVA was 1.2 cm2 in the study group compared to 1.6 cm2 in the control group (p = 0.02) over a mean follow-up of 17.5 +/- 11.7 months. Echocardiographic restenosis occurred in 4 patients (40%) in the ARF group compared to 1 patient (10%) in the control group (p = NS). The improvement in the New York Heart Association functional class was maintained in 8 patients of the ARF group and 9 patients of the control group. PTMC can be performed in children with ARF without an increase in procedural complications. However, the restenosis rates appear to be higher.

Acute Disease↗
PubMedDate not supplied

Obstructed infracardiac total anomalous pulmonary venous connection in an adult.

Adult survival in patients with uncorrected obstructed infracardiac total anomalous pulmonary venous drainage has not been reported. A 17-year-old man who presented to us with features of severe pulmonary arterial hypertension was diagnosed to have obstructed pulmonary venous drainage to the hepatic vein. Presence of a large ventricular septal defect in this patient may have contributed favorably to survival.

Adolescent↗
PubMedDate not supplied

Aortic valve balloon dilatation in infants with critical aortic stenosis.

Twenty-six infants aged 10 days-11 months (mean 3.5 +/- 2.4 months), with critical aortic stenosis underwent aortic valve balloon dilatation in last six years. In 19 (73%) infants, aortic valve balloon dilatation had to be performed as an emergency procedure. The systolic gradients decreased from 71.7 +/- 11.8 mm Hg to 21.0 +/- 8.1 mm Hg. There was no procedural death. Severe aortic regurgitation developed in two (7.7%) which was medically managed. Four (15.4%) infants had femoral artery thrombosis following aortic valve balloon dilatation and all responded to intravenous streptokinase. Congestive heart failure resolved in all (100%). Two infants developed endocarditis during follow-up after aortic valve balloon dilation and one of them died, another patient died of severe pulmonary artery hypertension. In the surviving 24 infants, left ventricular function improved markedly. On follow-up of 18 +/- 5 months, restenosis developed in two (7.7%) patients. We conclude that aortic valve balloon dilatation is safe and effective treatment for infants with critical aortic stenosis and severe left ventricular dysfunction.

Aortic Valve Stenosis↗