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Biomedical subjects

S Subramanian

Publications and source records attributed to S Subramanian.

At least 271 records · Page 15Linked to original sources
PubMed1980

Dihydrofolate reductases from chicken liver and Lactobacillus casei bind Cibacron blue F3GA in different modes and at different sites.

The binding of Cibacron blue F3GA to dihydrofolate reductase (EC 1.5.1.3) from chicken liver an amethopterin-resistant Lactobacillus casei has been studied by difference spectroscopy. The blue dye binds to the enzyme from each species in a specific fashion with a 1:1 stoichiometry. However, the mode of interaction of the dye with the enzyme and the site of interaction on the enzyme are very different for the avian and bacterial enzymes. The dye seems to bind in an almost totally "electrostatic mode" at the dihydrofolate binding site to the chicken liver enzyme and is displaced from the enzyme only by dihydrofolate, folate, or methotrexate and not at all by NADPH. In contrast, the binding of the dye to the bacterial enzyme is characterized by a totally "apolar interaction" at a site partially overlapping both the NADPH site and the methotrexate/dihydrofolate site. NADPH can displace the dye only partially and methotrexate is more efficient than NADPH in displacing the dye. Both NADPH and methotrexate are needed for a total displacement of the dye from the bacterial enzyme. We propose that the blue dye is capable of binding specifically to any protein possessing a cluster of aromatic and other apolar groups and/or geometrically spaced positively charged groups for proper interaction with the aromatic rings and/or sulfonate groups of the dye molecule. The so-called specificity of the blue dye for the nucleotide binding proteins is thus a special case of the above mentioned requirements and not diagnostic of the "dinucleotide fold."

Animals↗
PubMed1980

The thermodynamics of a negatively interacting allosteric effector system. The glutamate dehydrogenase . NADPH . ADP complexes.

The reaction catalyzed by bovine L-glutamate dehydrogenase is subjected to allosteric activation by ADP. We have measured the thermodynamic parameters (delta G0, delta H0, delta S0, and delta Cp) of the formation of the various possible binary and ternary complexes formed between the enzyme, NADPH, and either ADP or its analogs, adenosine, AMP, and ATP. delta H0 and delta Cp have been measured by flow calorimetry; delta G0 values obtained by calorimetry itself, differences spectroscopy, or gel filtration have been selected on the basis of accuracy under the conditions required for the formation of each complex. The data are interpreted in terms of "interaction parameters," the differences between the thermodynamic parameters of the formation of a ternary complex and the sum of those of the two related binary complexes. Both adnosine and ATP appear to loosen the binding of NADPH by simply preventing a subsite interaction of NADPH. AMP appears to have only minor and probably secondary effects. The negative effect of the binding of ADP on that of NADPH, however, involves the formation of a new interaction, which is exothermic, entropy compensated, has a moderately large negative delta Cp, and does not occur in either binary complex.

Adenosine↗
PubMed1980

Tubular hypoplasia of the descending thoracic aorta. Surgical treatment with a PTFE bypass graft under moderate total body hypothermia.

An 8 1/2-year-old child presenting with hypertension was noted to have tubular hypoplasia of the descending thoracic aorta without collateral circulation on angiography. Surgical management consisted of bypassing the hypoplastic segment (10 cm) using a 10 mm PTFE graft under total body hypothermia to minimize spinal complications. The patient had an uneventful recovery with normalization of blood pressures postoperatively.

Aorta, Thoracic↗
PubMed1980

Anomalous origin of the left coronary artery from the pulmonary trunk: its clinical spectrum and current surgical management.

An anomalous left coronary artery arising from the pulmonary artery is a rare congenital anomaly which carries a serious prognosis with a high mortality in infants. Our experience in the surgical treatment of 9 patients with this condition during the last 5 years is discussed. The majority of patients were under the age of 2 years and presented with left ventricular failure. Surgical procedures included simple ligation of the left coronary artery, left subclavian to left coronary artery anastomosis, interposition vein graft, and direct reimplantation of the left coronary artery into the aorta. Patients treated by simple ligation survived the procedure but did not show improvement. Results with the subclavian artery to left coronary artery anastomosis were disappointing. Direct reimplantation or interposition of a saphenous vein graft appears to be the method of choice.

Child↗
PubMed1980

Rhinosporidiosis in a south Indian village.

A brief survey for rhinosporidiosis in a South Indian village is presented. A total of 34 cases have been detected with a prevalence rate of 4.7%. This is found to be higher than all those reported already from India. A sex variation was noted in the incidence of this disease, which was quite differenat from all the earlier reports; the infection rate was higher in females than in males. More than one case has been detected in three families. Attempts to find any natural infection in the aquatic inhabitants such as snails, frogs, fishes and crabs found in the village pond have not been successful so far. One case of rhinosporidiosis in a cow in this endemic village was also recorded.

Adolescent↗
PubMed1980

Congenital diverticulum of the left atrium.

Two cases of congenital diverticulum of the left atrial appendage are described. The first patient was a 3-year-old girl who had a cerebral embolism. The second patient was a 3(1/2)-year-old girl with signs of pericarditis. Treatment consisted of excising the diverticula. The limited literature on diverticulum of the left atrium as a congenital abnormality is also briefly reviewed.

Journal Article↗
PubMed1980

Nocardia species from bronchopulmonary infections and mycetomas.

350 specimens comprising sputum, bronchial aspirate, pleural fluid, pus and biopsy material were investigated for the presence of Nocardia spp. by the paraffin bait technique. Nocardia spp. were isolated in 15 of them. The physiological and morphological characteristics of the organisms and the use of paraffin baiting, a selective technique for isolating Nocardia spp. from clinical specimens, are discussed.

Adult↗
PubMed1979

The enthalpy of protolysis of liver alcohol dehydrogenase upon binding nicotinamide adenine dinucleotide.

The binding of NAD+, NADH, and ADP-ribose to horse liver alcohol dehydrogenase has been studied calorimetrically as a function of pH at 25 degrees C. The enthalpy of NADH binding is 0 +/- 0.5 kcal mol-1 in the pH range 6 to 8.6. The enthalpy of NAD+ binding, however, varies with pH in a sigmoidal fashion and is -4.0 kcal mol(NAD)-1 at pH 6.0 and +4.5 kcal mol(NAD)-1 at pH 8.6 with an apparent pKa of 7.6 +/- 0.2. The enthalpy of proton ionization of the group on the enzyme is calculated to be in the range 8.8 to 9.8 kcal mol(H+)-1. In conjunction with the available thermodynamic data on the ionization of zinc-bound water in model compounds, it is concluded that the group with a pKa of 9.8 in the free enzyme and 7.6 in the enzyme . NAD+ binary complex is, most likely, the zinc-bound water molecule. Our studies with zinc-free enzyme provide further evidence for this conclusion. Therefore, the processes involving a conformational change of the enzyme upon NAD+ binding and the suggested mechanism of subsequent quenching of the fluorescence of Trp-314 implicating the participation of an ionized tyrosine group must be re-evaluated in the light of this thermodynamic study.

Adenosine Diphosphate Sugars↗
PubMed1979

Aorta-pulmonary artery shunts with expanded polytetrafluoroethylene (PTFE) tube.

Ten patients underwent an aortapulmonary artery shunt with a polytetrafluoroethylene (PTFE) tube between December, 1976, and October, 1977. Five of them were less than 1 month old. The diameter of the PTFE tube was 5 mm in 9 patients and 4 mm in 1 patient. Seven patients survived the operation. One of them had a clotted shunt, which was reoperated on successfully. Three patients died in the postoperative period, and all had a patent shunt. Overall patency was 90% (9/10). Congestive heart failure refractory to medical treatment developed in 1 patient with a patent Blalock-Taussig and PTFE shunt. In our institution, the Blalock-Taussig shunt is the procedure of choice. The PTFE shunt is used when the anatomy of a patient is unsuitable for a Blalock-Taussig shunt. A tube diameter of 5 mm is optimal for infants when further growth is considered, even if digitalization is necessary to control congestive heart failure.

Aorta↗
PubMed1979

Single-dose minocycline in the treatment of gonococcal urethritis. Clinical efficacy in relation to bacterial resistance and its effects on associated Chlamydia trachomatis infections.

Seventy-two men with gonococcal urethritis were given a single 300-mg dose of minocycline. The failure rate was 13% and the trial was terminated at an early stage. Failure was correlated with increased resistance of Neisseria gonorrhoeae to minocycline. The activity of penicillin, spectinomycin, erythromycin, tetracycline, sulphamethoxazole, cefuroxime, cefotaxime, rosamicin, thiamphenicol, and piperacillin against N. gonorrhoeae were examined in vitro. With the exception of spectinomycin, parallel patterns of resistance to the other antibiotics and minocycline were found. Resistance to spectinomycin was not found, confirming the usefulness of this antibiotic in the treatment of gonorrhoea. The incidence of PGU was significantly lower after a single dose of minocycline than in previous studies.

Anti-Bacterial Agents↗
PubMed1979

Effect of hypoxia on regional lung perfusion, by scanning.

Lung scanning was performed in 12 subjects who had pulmonary oedema of high altitude (POHA) before, and in 8 men who had been at high altitude without developing pulmonary oedema. Scanning done before and after 5 min 10% O2 breathing showed (a) increased perfusion in POHA subjects after hypoxia, (b) more in the lower than in upper zones, and (c) striking increase in perfusion in localised areas. In controls, however, there was significant reduction in perfusion after hypoxia in most areas. The reduction was less marked in the lower zones than in the upper zones. POHA subjects were hyperreactors to hypoxia, compared to controls. It is concluded that scanning before and after hypoxic breathing might help in differentiating hyperreactors.

Humans↗
PubMed1979

Coronary bypass in a patient with hemophilia B, or Christmas disease. Case report.

A 40-year-old patient with moderate factor IX deficiency (Christmas disease) underwent quadruple saphenous vein coronary bypass grafts for angina and severe coronary atherosclerosis involving the left and right main, left anterior descending, and circumflex coronary arteries. Excessive bleeding was prevented by infusion of factor IX concentrates during and after the operation. The surgical procedure and total body perfusion were carried out in the same manner as in patients without a hemorrhagic disorder. The patient was discharged after 13 days of hospitalization. He is doing well at the time of this publication and has returned to work.

Adolescent↗
PubMed1979

Human thymus cells: a study of rosette-forming capacity with unsensitized and sensitized erythrocytes of various species.

Human thymus cells from 117 donors aged 2 months to 15 years, were studied for rosette-forming capacity with unsensitized and sensitized erythrocytes of various species. Viability of the thymus cells at the completion of isolation ranged from 95 to 99%. Over 90% of the total population of thymus cells were identified as T lymphocytes by either standard Es-rosette assay utilizing a 4 degree incubation with preceding centrifugation or T--LCL assay, on the average. Gravity Es-rosette assay high affinity Es-rosette assay, stable Es-rosette assay or active Es-rosette assay for identification of subsets of T lymphocytes indicate that most of the human thymus cells were capable of forming rosettes with unsensitized sheep erythrocytes at higher degrees of temperature with or without preceding centrifugation. Approximately half of the human thymus cells were also capable of forming rosettes with unsensitized allogeneic erythrocytes. Less than 3% of the thymus cells expressed receptors for the Fc portion of IgG (T gamma suppressor cells) whereas less than 1% of thymus cells expressed receptors for the Fc portion of IgM (T mu helper cells), indicating that most of the thymus cells are non-T mu/non T gamma cells. Only 1% or less of the thymus cells were identified as B cells by the SIg assay, the Em-rosette assay or the Ia-like antigen assay. There was no significant difference of any rosette assay between males and females or among various age groups.

Adolescent↗