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Biomedical subjects

A Bhan

Publications and source records attributed to A Bhan.

At least 73 records · Page 4Linked to original sources
PubMed1992

Cusp-level chordal shortening for rheumatic mitral regurgitation: early results.

From February of 1987 through February of 1991, 25 patients with rheumatic mitral disease underwent cusp-level shortening of the chordae of the anterior mitral leaflet as part of the valvular reconstruction procedure at our institutions. All patients had moderate or severe mitral regurgitation, with prolapse of the anterior mitral leaflet. Seventeen patients also had mitral stenosis. Postoperative echocardiograms, both transthoracic and transesophageal, showed correction of leaflet prolapse and mitral regurgitation. This preliminary report suggests that the technique satisfactorily corrects mitral regurgitation in patients with elongated and thickened chordae characteristic of rheumatic mitral disease.

Journal Article↗
PubMed1991

Profile of coronary arterial disease in diabetic patients undergoing coronary arterial bypass grafting.

Diabetics are believed to have more extensive and diffuse lesions of the coronary arteries in presence of coronary arterial disease. We studied prospectively 52 diabetics with coronary arterial disease who underwent coronary arterial bypass grafting and evaluated their pre-operative symptomatology, angiographic appearance of coronary arteries, coronary arterial dimensions as assessed at surgery, and the post-operative complications. These were compared to 52 age and sex matched non-diabetic controls undergoing surgery during the same period. There was no statistically significant difference in the incidence of pre-operative symptomatology or frequency of myocardial infarction in the two groups. Left ventricular angiographic findings were also comparable, as was the observation on the extent and severity of coronary arterial disease as assessed by angiography and at surgery. Hence, we recommend coronary arterial bypass grafting to diabetics with the same criteria as are applied to non-diabetics, confident that there will be no added morbidity and mortality.

Adult↗
PubMed1989

Conformational studies of two isomeric ring-expanded purine nucleosides and their 5'-mono- and -diphosphate derivatives.

The nucleosides Ia and IIa exist in syn and anti conformations, respectively, both in solid state and solution. Compound Ia undergoes significant conformational change, accompanied by increased population of the anti conformer, upon conversion to the corresponding 5'-mono- and- diphosphate derivatives, whereas conformation of IIa remains reasonably constant between nucleoside and nucleotides. While Ia possessed the C2'-endo-C3'-exo geometry, IIa had the opposite C2'-exo-C3'-endo conformation. The C5' of the two nucleosides bore axial and equatorial conformations, respectively.

Dimethyl Sulfoxide↗
PubMed1989

The combination of a left aortic arch, a right-sided descending thoracic aorta with a left-sided arterial duct.

A nine-year-old male child presented with a history of recurrent chest infections and breathlessness. On investigation, he was found to have a left aortic arch with a right-sided descending thoracic aorta along with a left-sided arterial duct. He also had mild aortic stenosis with regurgitation. The duct was successfully ligated under controlled hypotensive anesthesia through a left posterolateral thoracotomy.

Aorta, Thoracic↗
PubMed1986

Erythema multiforme in a patient with T cell chronic lymphocytic leukemia.

A patient with T4+ (helper-inducer) T cell chronic lymphocytic leukemia developed an erythema multiforme-like eruption, the diagnosis of which was supported by routine light microscopic findings. Immunopathologic studies using monoclonal antibodies demonstrate that despite an overwhelming majority of leukemic T4+ cells in the peripheral blood and dermal infiltrate, the predominant cells in the epidermal infiltrate are T8+ (cytotoxic-suppressor) cells. These findings are different from those seen in epidermotropic T cell leukemic infiltrates and are similar to those previously reported in erythema multiforme. Thus it is likely that the leukemic T4+ cells are participating in this cutaneous hypersensitivity reaction along with residual, normal T8+ cells.

Aged↗
PubMed1984

Monoclonal antibodies to tissue-specific cell surface antigens. I. Characterization of an antibody to a prostate tissue antigen.

Monoclonal antibodies were raised to PC-3 human prostate adenocarcinoma cells, and one hybridoma, designated F77-129, was extensively purified and used to characterize a PC-3 antigen. The F77-129 antibody also showed serological reactivity with the Du-145 prostate cancer line and with three of four breast carcinoma lines tested; it showed variable binding to a colon carcinoma line. Several other lines tested, including melanomas, fibrosarcomas, and leukemias, were completely negative. Immunoperoxidase staining of frozen surgical specimens showed binding to both normal and malignant prostate and breast tissue. Injection of radioiodinated F77-129 into tumor-bearing nude mice showed specific in vivo targeting to prostatic cancer implants. The antigen also showed surface modulation by bound antibody, suggesting possible clinical utility of this antibody in delivering immunotoxins to tumors.

Adenocarcinoma↗
PubMed1981

Subunit function in cardiac myosin. Effects of binding phosphorylated and unphosphorylated myosin light chain 2 to light chain 2-deficient myosin.

The 20,000-dalton light chain of cardiac muscle myosin can be specifically digested and thereby removed from the rest of the myosin molecule by incubation with a myofibrillar protease (Malhotra, A., Huang, S., and Bhan, A. (1979) Biochemistry 18, 461-467). In order to study the effects of phosphorylation of the 20,000-dalton myosin light chain, experiments were carried out with cardiac muscle myosin that was made deficient in this light chain following proteolysis. Both the phosphorylated and unphosphorylated isolated 20,000-dalton myosin light chain of cardiac muscle myosin were found to bind to light chain-deficient myosin. Prior to readdition of the isolated light chains, this light chain-deficient myosin was found to have a higher MgATPase activity in the presence and absence of actin, than native myosin. Binding of the unphosphorylated myosin light chain restored the MgATPase activity of light chain-deficient myosin to that of native cardiac myosin. In contrast, the binding of 2 mol of the previously phosphorylated myosin light chain did not lower the actin-activated MgATPase activity. The results suggest that while phosphorylation of the 20,000-dalton light chain of cardiac muscle myosin is not essential for the actin-activated MgATPase activity, it may have a modulatory role.

Animals↗
PubMed1979

Hereditary and acquired cardiomyopathies in experimental animals: mechanical, biochemical, and structural features.

Evidence has been presented regarding alterations of contractile behavior muscle biochemistry, and ulstrastructure during the course of the hereditary hamster cardiomyopathy. Also, preliminary structural and mechanical data were presented on the acquired cardiomyopathy of diabetes mellitus in experimental animals. In the hamster model, contractile performance, measured as isometric tension and rate of tension development, was shown to be depressed throughout the course of the disease, whereas normalized force-velocity relationships returned to normal only during the compensated stages of hypertrophy. Force-frequency relationships were depressed in myopathic muscles, indicating the presence of alterations in the muscle activation system, namely, the biochemical and functional integrity of the sarcoplasmic reticulum. Analysis of the contractile proteins in myopathic muscle has revealed depressions of Ca2+ activity in purified myosin in addition to an independently increased neutral protease activity that results in the specific degradation of LC2 of myosin. Sympathetic time and norepinephrine turnover increase progressively during the course of the disease. These changes are accompanied by decreasing tissue levels of neorepinephrine and increasing levels of dopamine, indicating a shift in the rate-limiting step for norepinephrine synthesis. Alterations were also noted in nuclear protein composition and serotonin levels. Microscopically, the myolytic and calcification changes that characterize the hamster cardiomyopathy have been confirmed. In addition, contraction bands and lysosomal changes have been observed that may relate to cateholamine hypersensitivity. In the experimental model of diabetic cardiomyopathy, a significant alteration in relaxation process was demonstrated despite the fact that peak tension development and its rate of development were unaltered. Also, the length dependence of contractile behavior was altered when compared to that of age-matched controls, indicating a potential loss of contractility reserve. When animals with combined hypertension and diabetes were studied, bothe contraction and relaxation processes were affected to a greater degree.

Actomyosin↗
PubMed1976

Cardiac actomyosin ATPase activity after prolonged physical conditioning and deconditioning.

Cardiac actomyosin ATPase was increased by making rats swim 150 min/day, 5 days/wk for 8 wk. Changes in Ca2+ -stimulated ATPase activity were then studied in these conditioned rats and in similarly conditioned animals in which swimming was subsequently discontinued (group A), reduced to 45 min/day (group B), or continued at the original level for an additional 8 wk (group C). After the 8-wk initial program actomyosin ATPase activity averaged 22% higher in hearts of conditioned rats than in hearts of sedentary controls (P is less than 0.001). In group A, actomyosin ATPase activity declined rapidly and reached the level found in sedentary controls by the 13th day. In group B, actomyosin ATPase activity declined to the control level by the 30th day. At the end of 16 wk the percent increase in actomyosin ATPase activity in group C over that in hearts of sedentary animals was approximately the same as after 8 wk. These results demonstrate that elevation in cardiac actomyosin ATPase caused by moderate physical training in rats is not maintained if the training program is decreased or discontinued. The training program must be continued at or near the initial level if the increases in cardiac actomyosin ATPase are to be sustained.

Actomyosin↗