Search PubMed⌕ Search

Biomedical subjects

D Mukherjee

Publications and source records attributed to D Mukherjee.

At least 91 records · Page 5Linked to original sources
PubMed1995

Quantification of myotrophin from spontaneously hypertensive and normal rat hearts.

A novel peptide, myotrophin, has been isolated, purified, cloned, and sequenced from the hearts of spontaneously hypertensive rats (SHR) and from dilated cardiomyopathic human heart tissue. Myotrophin accelerates myocyte growth by stimulating protein synthesis (not by altering myocardial cell division). Our successive studies were conducted to evaluate the pathophysiological significance of myotrophin; a solid-phase radioimmunoassay technique was developed for quantifying the protein in hypertrophied and normal hearts. Specific antipeptide antibody was raised in rabbits against a peptide that represents a selected amino acid sequence of a 17-amino acid myotrophin segment by using the multiple antigenic peptide technique. The specificity of the antibody was evaluated by determining the affinity constant after constructing the Scatchard plot obtained from the ratio of bound to free myotrophin against bound myotrophin. The value obtained was 2.61 x 10(7) L/mol. The specificity was further demonstrated by Western blot analysis, in which a single protein band was obtained in the region of 12 kD. Pretreatment of the antibody with myotrophin completely blocked the binding sites, because no protein band was detected on the immunoblot. The antibody prevented the myocardial protein synthesis induced by myotrophin as revealed by the blockage of the stimulation of [3H]leucine incorporation into myocyte protein. Quantification of myotrophin from different heart tissues was achieved by Western blot and dot blot analyses. Amounts of myotrophin present in different dots were determined by using a video image analyzer. The level of myotrophin in the embryonic tissue was found to be similar in male normal and SHR hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

Lack of pharmacokinetic interaction between zileuton and phenytoin in humans.

A randomised double-blind crossover study was undertaken in 20 healthy adult male volunteers to assess the effects of multiple oral dose administration of zileuton (600mg every 6 hours for 8 days) on the single dose pharmacokinetics of phenytoin 300mg. Serial blood samples were collected up to 72 hours after phenytoin administration and plasma concentrations were determined by high performance liquid chromatography. Pharmacokinetic data were analysed utilising noncompartmental and Michaelis-Menten-based population pharmacokinetic analysis. Zileuton did not significantly alter the peak plasma concentration, time to peak plasma concentration, and area under the plasma concentration-time curve of phenytoin. Moreover, population analysis revealed no significant effect of zileuton on the Michaelis-Menten parameters of phenytoin. Thus, coadministration of multiple doses of zileuton (2.4 g/day) did not significantly affect the single dose pharmacokinetics of phenytoin.

Administration, Oral↗
PubMed1995

A new autogenous conduit for the spleno-renal shunt.

Management of patients with portal hypertension has been significantly advanced by new medical, surgical and radiologic procedures. In the presence of portal vein thrombosis, a splenorenal shunt is the procedure of choice for relief of portal hypertension. The gonadal vein is an autogenous conduit of ideal diameter to accomplish this objective. Several advantages of this new operation are described.

Female↗
PubMed1994

Pharmacokinetics of valproate after multiple-dose oral and intravenous infusion administration: gastrointestinal-related diurnal variation.

A randomized, crossover study was conducted in healthy male volunteers to assess the diurnal variation in the steady-state pharmacokinetics of valproate after multiple 250-mg oral and intravenous infusion doses after an intravenous 750-mg loading dose. Multiple blood samples were collected throughout each 168-hour study period, and plasma valproate concentrations were quantitated using a gas chromatographic technique. Within-regimen comparisons indicated statistically significant differences for mean steady-state peak (Cmax) and trough (Cmin) plasma concentrations and area under the plasma concentration-versus-time curve (AUC) between the second and third doses on day 4 after oral dosing, indicating a diurnal variation in the rate of valproate absorption from the delayed-release tablet preparation. Between-regimen steady-state comparisons of pharmacokinetic parameters revealed some significant differences in mean time to Cmax (Tmax), Cmax, Cmin, AUC, and total body clearance for respective day-4 dosing intervals, but not for the entire day 4, except for Cmin and Tmax. Mean elimination rate constant and half-life did not significantly differ between the regimens. The regimens were bio-equivalent at steady state, as assessed by 90% confidence intervals (two one-sided test procedures) for Cmax, Cmin, and AUC, with similarity in degrees of fluctuation ((Cmax-Cmin)/Caverage). Despite the presence of diurnal variation in valproate absorption after oral dose administration, the steady-state plasma concentration-versus-time profile was well maintained by both regimens within the accepted therapeutic range of 50 to 100 micrograms/mL.

Administration, Oral↗
PubMed1994

Posterior approach to the peroneal artery.

The posterior approach to the peroneal artery is described and illustrated by two case reports. The arterial inflow source was the popliteal artery, and the lesser saphenous vein in the reversed position was the bypass conduit. The approach was found to afford excellent exposure and is the logical choice when the inflow source, the distal target vessel, and the bypass conduit are readily accessible from the posterior aspect.

Aged↗
PubMed1994

Functional relevance of luteinizing hormone receptor in mouse uterus.

The presence of high-affinity luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptors has been reported in porcine, rabbit, rat and human uteri. We have demonstrated binding of [125I]LH to mouse uterus, which was saturable. Scatchard plot analysis indicated Kd to be 1.37 x 10(-10) mol/l and the maximum binding capacity to be 5.24 nmol/kg protein. Attempts have been made to observe the functional relevance of gonadotropin receptor in the mouse uterus. The size and weight of the uterus remarkably decreased as a result of ovariectomy; administration of LH to ovariectomized (OVX) mice significantly increased the uterine weight in comparison to the OVX control (p < 0.01), indicating a direct effect of LH on the uterus. There was a two-fold decrease of uterine ascorbic acid content in LH-treated OVX mice as compared to the intact control. The gain in uterine weight of OVX mice by LH was due to the increase in uterine protein synthesis. The stimulatory effect of LH on OVX mice uterus appears to be mediated via steroid hormones because it significantly augmented uterine mitochondrial steroidogenesis. Since 17 beta-estradiol (E2) is known to stimulate uterine protein synthesis, the circulatory level of E2 was determined in intact, OVX and OVX + LH-treated mice. A fall in the circulatory level of E2 occurred in OVX mice as compared to the control, while treatment of LH for 7 days (three injections) significantly elevated E2 levels in OVX mice (p < 0.001). This higher level of E2 in OVX mice remains unaltered on adrenalectomy, indicating that adrenals are not the source for increased E2 levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

Effect of mercuric chloride and cadmium chloride on gonadal function and its regulation in sexually mature common carp Cyprinus carpio.

Gonadal function in fish, Cyprinus carpio was significantly affected by sublethal doses of mercuric chloride (HgCl2) and cadmium chloride (CdCl2) in chronic (45 days) exposure. Parameters investigated were nonesterified (NE) and esterified (E) cholesterol of ovary, liver and serum and ovarian 3 beta-Hydroxysteroid and 17 beta-Hydroxysteroid dehydrogenase enzyme activity and serum and pituitary gonadotropin (GtH) levels. Both the pollutants were able to reduce the hypothalamic extract (HE) or gonadotropin releasing hormone (GnRH) induced pituitary GtH release in vitro. Short term (96h) exposure of the fish to the pollutants had no significant effect on the gonadal function. In addition to the deleterious effect of pollutants on the gonadal steroidogenesis and pituitary gonadotropin release, using [4-14C] cholesterol as a tracer it was found that for 45 days exposure, HgCl2 had an adverse effect on the transport of cholesterol from circulation to ovary.

Animals↗
PubMed1993

Radiofrequency catheter ablation of ectopic atrial tachycardia using paced activation sequence mapping.

OBJECTIVES: Although ectopic atrial tachycardia is infrequent, it can be an important clinical challenge. We sought to define an alternative therapeutic approach to this refractory problem. BACKGROUND: Radiofrequency energy catheter ablation has been used to treat a variety of ventricular and supraventricular arrhythmias but has not been proved efficacious in the management of ectopic atrial tachycardia. METHODS: Ten patients (14 to 47 years of age) referred with refractory ectopic atrial tachycardia were studied. Mapping techniques included identification of earliest atrial activation, confirmation of concordance of P wave configuration during spontaneous tachycardia and pacing from the ablation catheter, and paced activation sequence mapping. The paced activation sequence mapping compared the activation sequence at multiple atrial sites during spontaneous tachycardia with that recorded during pacing from the ablation catheter. The catheter was steered to a point where pacing reproduced the spontaneous activation sequence. RESULTS: Foci were right atrial in eight patients and left atrial in two. In 8 of 10 patients, 514 +/- 97 (SE) J and 5.7 +/- 2.3 (SD) J radiofrequency energy applications ablated the ectopic focus. Seven of these eight patients presented with one focus and one had two discrete and stable foci. Ablation was unsuccessful in two patients with multiple foci. No complications occurred. An arrhythmia focus recurred in two patients and one patient underwent successful repeat ablation. The other patient was managed medically. All seven patients with successful ablation are symptom free after 6.5 +/- 3.8 months. CONCLUSIONS: Our preliminary experience suggests that with the use of both paced activation sequence mapping and standard techniques, radiofrequency ablation of ectopic atrial tachycardia may be a safe and effective form of therapy.

Adolescent↗
PubMed1993

Studies on the hypocalcemic actions of salmon calcitonin and ultimobranchial gland extracts in the freshwater teleost Cyprinus carpio.

A single injection of synthetic salmon calcitonin (sCT) or homologous ultimobranchial gland (UBG) extract caused a significant reduction in total and ultrafiltrable plasma Ca2+ in a freshwater teleost, Cyprinus carpio. A time-bound analysis on the effect of sCT or UBG extract caused a short-duration hypocalcemia and the response was more pronounced in fish kept in low-Ca2+ water. Sexually immature fish showed a greater response than did mature fish. In all the studies the protein-bound Ca2+ fraction remained unaffected. The observation thus indicate a potent hypocalcemic role of calcitonin or UBG in freshwater common carp under laboratory conditions.

Animals↗
PubMed1993

Alteration of cardiac collagen phenotypes in hypertensive hypertrophy: role of blood pressure.

The myocardium contains a fibrillar collagen matrix that consists primarily of type I and type III collagens. There is a marked alteration in the ratio and amount of collagen phenotypes in myocardial hypertrophy due to pressure overload. The purpose of the present study is (1) to study the effect of antihypertensive therapy on collagen phenotypes, if instituted before development of hypertension in spontaneously hypertensive rat (SHR), and continued into adult life and (2) to study the effects of dissociation of hypertension from hypertrophy, on collagen phenotypes in SHRs. The present study shows the effect of two antihypertensive drugs, hydralazine and captopril, on collagen phenotypes in SHRs. Both hydralazine and captopril effectively controlled blood pressure in SHRs, but only captopril regressed hypertrophy and corrected the altered distribution of myocardial collagen phenotypes I and III. Untreated SHRs had a collagen type I:III ratio of 10.19 +/- 0.27, compared with that of 6.41 +/- 0.30 in normotensive WKY (P < 0.001). Captopril-treated SHRs had a collagen type I:III ratio of 6.75 +/- 0.37, which did not differ significantly from that in normotensive WKY. Hydralazine-treated SHRs had a collagen I:III ratio of 10.07 +/- 0.39, which is similar to the ratio in untreated SHRs. In normotensive rats, neither captopril nor hydralazine significantly altered collagen content or the ratio of type I:III collagen. Thus captopril, an angiotensin converting enzyme inhibitor, not only regressed hypertrophy but also reversed the altered distribution of type I and type III collagen whereas hydralazine which effectively controlled blood pressure, did not regress hypertrophy and did not correct the altered distribution in collagen phenotypes. These studies suggest that alteration of collagen phenotypes during hypertensive hypertrophy is independent of blood pressure control and myocardial mass.

Animals↗
PubMed1993

The effect of diffusion on two predators exploiting a resource.

This paper deals with the stabilizing effect of diffusion on a system of a living resource supporting two noncompeting predators. It is shown that while the three species mathematical model without diffusion is unstable, the model with diffusion is asymptotically stable provided the diffusion coefficient of the resource exceeds a certain threshold value.

Animals↗
PubMed1993

Rescue of failed forearm arteriovenous access grafts using an externally supported polytetrafluoroethylene graft.

Thrombosis of the forearm arteriovenous access graft is common. Graft failure usually occurs at the venous anastomosis. Thrombectomy with jump extension to a more proximal unobstructed vein is recommended. A polytetrafluoroethylene graft with externally supported rings across the elbow joint has been used as the extension conduit in eight patients over the past 18 months. Satisfactory prolongation of graft patency for 6 months or more was achieved in seven of these eight patients.

Arteriovenous Shunt, Surgical↗