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Biomedical subjects

A Nath

Publications and source records attributed to A Nath.

At least 145 records · Page 8Linked to original sources
PubMed1990

Mechanism of the inhibition by insulin of the glucagon-dependent activation of the phosphoenolpyruvate carboxykinase gene in rat hepatocyte cultures. Action on gene transcription, mRNA level and -stability as well as hysteresis effect.

The mechanism of the antagonistic action of insulin on the glucagon-dependent stimulation of the phosphoenolpyruvate carboxykinase (PEPCK) gene was studied in primary cultures of rat hepatocytes. Gene expression was monitored by the transcriptional activity of the PEPCK gene and the accumulation and degradation of PEPCK mRNA. 1) Insulin in concentrations from 0.1 to 100nM shifted the dose-response curve of the glucagon-dependent accumulation of PEPCK mRNA to the right, increasing the half-maximally effective glucagon concentration gradually from 0.1 to 0.7nM. At saturating 10nM glucagon concentrations insulin was not antagonistic. 2) Glucagon at 0.1nM concentrations increased PEPCK gene transcription and PEPCK mRNA to a transient maximum at 0.5 and 2 h, respectively. Insulin, added at 10nM concentrations simultaneously with glucagon, reduced the maximal increase in PEPCK gene transcription by 70% and in PEPCK mRNA by 45%, respectively. 3) Following the maximal glucagon-induced increase after 2 h PEPCK mRNA declined to half-maximal levels after another 2.3 h. Insulin, added at 2 h at the PEPCK mRNA maximum, accelerated the disappearance of PEPCK mRNA, which reached half-maximal values already after another 1.2 h. 4) The transcriptional inhibitor cordycepin, added at 2 h at the PEPCK mRNA maximum, clearly retarded the normal and the insulin-accelerated decay of PEPCK mRNA so that half-maximal levels were reached only after another 5 h and 3 h, respectively. However, cordycepin did not retard the decay of PEPCK mRNA, when insulin was present from the beginning of induction by glucagon.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Simultaneous left ventricular and ascending aortic pressure measurements via single artery access for assessment of aortic stenosis.

In order to determine the reliability of a single arterial access technique for hemodynamic assessment of aortic stenosis, data obtained from this method was compared with that from dual arterial access in 13 patients. A 59 cm long, 8 Fr. Mullins Transseptal Sheath (MTS) was placed in the ascending aorta (AA) and a 5 Fr. pigtail catheter advanced through the MTS (using a hemostatic "Y" adapter) into the left ventricle for simultaneous pressure recordings. Another 5 Fr. pigtail catheter (PTC) was advanced in the AA from the contralateral femoral artery. Peak pressures, AA pressure-tracing characteristics, mean gradients, and the aortic valve area using tracings from the MTS and the PTC were compared. Peak pressures 120 +/- 8 vs. 119 +/- 8 mmHg (r = .998), "T" time .16 +/- .01 vs. .15 +/- .01 sec. (r = .913), "U" time .36 +/- .02 vs. .36 +/- .02 sec. (r = .983), mean gradients 38.4 +/- 6.1 vs. 39.6 +/- 6.9 mmHg (r = .990) and the AV area .78 +/- .08 vs. 79 +/- .08 cm2 (r = .994) were similar. Therefore, this single arterial technique provides data comparable to the traditional dual access system for hemodynamic assessment of aortic stenosis.

Aged↗
PubMed1989

Accelerated aortic stenosis.

A 56 year-old woman presented in congestive heart failure 4 weeks after cardiac catheterization. By repeat catheterization, the mean gradient across the native aortic valve had progressed from 10 mm Hg to 51 mm Hg. In patients with calcific-degenerative valvular disease, the rapid worsening of aortic stenosis should be considered in the differential diagnosis of recurrent heart failure.

Aortic Valve Stenosis↗
PubMed1989

Anti-idiotypic antibodies to rubella virus.

Polyclonal and monoclonal anti-idiotypic (Ab2) and monoclonal anti-anti-idiotypic antibodies were generated against rubella virus-specific neutralizing and/or hemagglutination inhibiting monoclonal antibodies. None of the characterized Ab2's recognized the putative rubella virus receptor.

Antibodies, Anti-Idiotypic↗
PubMed1989

Effect of cyclosporine on rubella virus-specific immune responses in chronic progressive multiple sclerosis.

Cyclosporine A (CsA) has been used in putative autoimmune diseases after sensitization to unknown antigens. We have previously shown that CsA prevented continued activation of T-cells in chronic progressive multiple sclerosis (CPMS) patients. The current study was undertaken to determine whether CsA, or CsA and prednisone (CsA + P) could suppress immune responses to a common recall antigen. Serum antibody levels were higher in all CPMS patients than age-matched normal controls. However, rubella antibody titers in the CsA or CsA + P groups were no different from a placebo-treated CPMS patient group. The lymphocyte responses to inactivated rubella virus of CsA and CsA + P-treated CPMS patients were lower than placebo and control but not statistically different. Therapy with both CSA and CSA + P was associated with significantly lower panel mixed leukocyte responses and Ta1 expression than in the placebo-treated group; CD3, CD4, CD8 antigen expression and active rosette formation by T-cells were similar for the three CPMS groups. These results suggest that while CsA exerts measurable effects on non-specific indicators of cellular immunity in CPMS patients, it may not be as effective in suppressing pre-existent specific immune responses.

Antibodies, Viral↗
PubMed1989

Pharmacology of alpha/beta arteether--a potential antimalarial drug.

Pharmacological studies on alpha/beta arteether (a 30:70 mixture of isomers), a potential drug for the treatment of cerebral malaria, were carried out in experimental animals by giving the drug in arachis oil suspension. The compound appears to be devoid of significant pharmacological activity on the central nervous, cardiovascular and urinary systems. It lacks an anti-inflammatory response in rats up to 50 mg/kg intramuscularly but at 50-200 mg/kg it has some antianaphylactic potential.

Animals↗
PubMed1988

Regulation of the expression of the phosphoenolpyruvate carboxykinase gene in cultured rat hepatocytes by glucagon and insulin.

The induction of phosphoenolpyruvate carboxykinase (PEPCK) by glucagon was studied in primary rat hepatocyte cultures by determining the time course of the sequential events, increases in the enzyme's mRNA abundance, synthesis rate, amount and activity, and by investigating the antagonistic action of insulin on the induction by glucagon. 1. The mRNA of PEPCK was induced maximally 2-3 h after addition of 10 nM glucagon, as detected by Northern-blot analysis after hybridization with a biotinylated antisense RNA of PEPCK. 2. The synthesis rate of PEPCK increased maximally 2-3 h after application of glucagon as revealed by pansorbin-linked immunoprecipitation of [35S]methionine-labelled PEPCK. 3. The enzyme amount and activity was maximally induced 4 h after glucagon application. 4. The mRNA of PEPCK was half-maximally induced by 0.1 nM and maximally by 1 nM and 10 nM glucagon. The half-maximal induction by 0.1 nM glucagon was antagonized almost totally, and the maximal induction by 1 nM glucagon partially, while the maximal induction by 10 nM glucagon remained unaffected by 10 nM insulin. The results show that in cultured rat hepatocytes physiological concentrations of glucagon stimulated the induction of PEPCK by an increase in mRNA, that the glucagon-dependent increase in mRNA and enzyme-synthesis rate occurred in parallel and preceded the increase of enzyme amount and activity by 1-1.5 h, and that physiological levels of insulin antagonized the induction by glucagon in the physiological concentration range, with glucagon being the dominant hormone.

Animals↗
PubMed1988

Sensitivity and specificity of electrocardiographic criteria for left and right ventricular hypertrophy in morbid obesity.

To determine the sensitivity and specificity of standard electrocardiographic criteria for left ventricular (LV) and right ventricular (RV) hypertrophy in morbid obesity, resting electrocardiograms and M-mode echocardiograms were obtained in 65 patients whose actual body weight was more than twice their ideal body weight and who were free from hypertension and organic heart disease not directly attributable to obesity. Electrocardiographic criteria for LV hypertrophy were tested using increased LV wall thickness, LV enlargement and increased LV mass (all determined echocardiographically) as diagnostic standards. Electrocardiographic criteria for RV hypertrophy were tested using echocardiographic RV enlargement or RV hypertrophy as a diagnostic standard. Sensitivity values for the electrocardiographic criteria for LV hypertrophy ranged from 0 to 13%, 0 to 20% and 0 to 12% using echocardiographic increased LV wall thickness, LV enlargement and increased LV mass, respectively, as diagnostic standards. Specificity values ranged from 73 to 100%, 87 to 100% and 83 to 100%, respectively, using these diagnostic standards. Sensitivity values for the electrocardiographic criteria for RV hypertrophy ranged from 0 to 16% and specificity values ranged from 95 to 100%. Combining electrocardiographic criteria within groups did not appreciably increase sensitivity and often decreased specificity to unacceptably low levels. The electrocardiogram is very limited in its ability to detect ventricular hypertrophy and chamber enlargement in morbidly obese patients.

Adult↗
PubMed1988

Double-wire angioplasty of the right coronary artery bifurcational stenosis.

Two cases of distal right coronary artery (RCA) bifurcational stenoses involving ostia of the posterolateral (PLA) and the posterior descending (PDA) branches in patients who underwent successful coronary angioplasty using a double-wire technique are reported. A single guiding catheter and sequential balloon inflations were utilized in one, and two guiding catheters and simultaneous balloon inflations in the other. The indications, techniques, and outcomes are described.

Angiography↗
PubMed1988

Serial immune evaluation of cyclosporine- and placebo-treated multiple sclerosis patients.

During an ongoing clinical trial of cyclosporine (CsA) immunosuppression therapy for chronic progressive multiple sclerosis (MS), a comparison was made of the immune responses of 18 CsA- and 18 placebo (P)-treated MS patients. Patients randomized to receive either CsA or P had identical entry immune profiles. However, these MS patients displayed significantly increased T-helper:T-suppressor (TH:TS) ratios (P less than 0.01), percentage (%) active-T (P less than 0.01), % Ia+-T (P less than 0.05) and % Ta1+-T (P less than 0.01) cell phenotypes when compared to age-matched normal controls. Further, the MS-P-treated patients displayed significant increases (all P less than 0.01) in % pan-T, % helper-T, % active-T and % Ta1+-T cell phenotypes as well as panel mixed lymphocyte culture (panel MLC) functional responsiveness from entry to cumulative 12-month study data. In contrast, the MS-CsA-treated patients only displayed an increased % pan-T cell phenotype. The cumulative 12-month follow-up data showed that the MS-P-treated patients displayed significantly higher immune parameters than the MS-CsA-treated patients for % pan-T (P less than 0.05), % helper-T (P less than 0.01), TH:TS ratio (P less than 0.05), % active-T (P less than 0.01), % Ta1+-T cells (P less than 0.01) and panel MLC stimulation index (P less than 0.01). Thus, MS-CsA-treated patients did not display the progressive immune activation seen on serial evaluation during the follow-up time period that characterized the placebo-treated MS group.

Acute Disease↗
PubMed1987

Increase of urate formation by stimulation of sympathetic hepatic nerves, circulating noradrenaline and glucagon in the perfused rat liver.

In the isolated rat liver perfused in situ stimulation of the nerve bundles around the portal vein and the hepatic artery caused an increase of urate formation that was inhibited by the alpha 1-blocker prazosine and the xanthine oxidase inhibitor allopurinol. Moreover, nerve stimulation increased glucose and lactate output and decreased perfusion flow. Infusion of noradrenaline had similar effects. Compared to nerve stimulation infusion of glucagon led to a less pronounced increase of urate formation and a twice as large increase in glucose output but a decrease in lactate release without affecting the flow rate. Insulin had no effect on any of the parameters studied.

Allopurinol↗
PubMed1987

Metastatic renal cell carcinoma simulating glomus jugulare tumor.

A 59-year-old man presented with jugular foramen syndrome caused by a mass with roentgenographic and histologic features highly suggestive of a glomus jugulare tumor. However, electron microscopic examination of the surgical specimen revealed features diagnostic of a previously unsuspected renal cell carcinoma. Because primary tumors of the glomus jugulare and metastatic renal cell carcinoma may present with the same clinical and roentgenographic findings and look similar histologically, careful electron microscopic examination of the tumor and urologic screening should be performed in suspected cases of glomus jugulare tumors.

Carcinoma, Renal Cell↗
PubMed1987

Anomalous right coronary artery arising from the midportion of the left anterior descending coronary artery--case reports.

Although coronary artery anomalies are detected during 0.8-1.2% of routine adult cardiac catheterizations, anomalies of the right coronary artery are relatively uncommon and are generally of no clinical significance. This report focuses, however, on 2 patients whose RCA originated from the midportion of the left anterior descending artery, an anomaly with potentially important clinical implications, which are explored.

Aged↗
PubMed1987

Movement disorders and AIDS.

We studied seven patients with AIDS or AIDS-related complex (ARC) and movement disorders. Three had hemichorea-ballismus, two had segmental myoclonus, one had postural tremor with dystonia, and one had paroxysmal dystonia. Besides the hyperkinesias, two patients had parkinsonism, and one had cerebral Whipple's disease. In two, the movement disorder preceded other evidence of AIDS; in three others, the diagnosis of AIDS was not considered until there was a movement disorder. The movement disorders were attributed to toxoplasmosis in four patients (one confirmed at autopsy), viral encephalitis, vacuolar myelopathy, and CNS Whipple's disease.

Acquired Immunodeficiency Syndrome↗