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Biomedical subjects

K Chandrasekaran

Publications and source records attributed to K Chandrasekaran.

119 records · Page 7Linked to original sources
PubMed1980

Subcellular distribution of simian virus 40 T antigen species in various cell lines: the 56K protein.

The subcellular distribution of SV40 anti-T serum-specific species was examined in SV40-transformed, T-antigen-positive tissue culture cell lines of rat and of AL/N and BALB/c mouse origin. Cells were labelled with [35S]methionine. The cytoplasm, nuclear and membrane fractions were obtained, and their radioimmunoprecipitates analyzed by gel electrophoresis. Tests were performed to determine the purity of these subcellular fractions, and negligible cross-contamination was found. The cytoplasm fractions lacked detectable anti-T serum reactivity. Large amounts of both large T antigen and a 56K protein were always present together both in the nuclear fractions and, in a somewhat lesser amount, in the plasma membrane fractions of all cell lines examined. Analysis of density gradient sedimentation profiles of the immunoprecipitates of whole-cell extracts indicated these species were associated in some fashion, probably with each other. The activity of the 56K protein may be associated with its presence on the cell surface where, either alone or acting together with the large T antigen, it might provide the surface activity responsible for tumor-specific surface and/or transplantation antigen activities.

Animals↗
PubMed1980

Assembly of mitochondria in yeast. Complementation of mitochondrial and cytosolic products in a temporal sequence in vitro.

1. Sequential transfer of derepressing yeast spheroplasts from a medium containing chloramphenicol to one containing cycloheximide or vice versa, shows that the cytosolically and mitochondrially synthesized products are synthesized independent of each other and accumulate in the absence of their counterparts. 2. This has been demonstrated by immunoprecipitation using specific antisera for cytochrome oxidase and ATPase enzymes. 3. The independently accumulated products have been shown to complement each other for the expression of enzyme activity, upon mixing in vitro. 4. By varying the time of treatment with cycloheximide, thereby allowing the mitochondrial protein synthesis to proceed to different extent, a time sequence in the appearance of the mitochondrially synthesized products is demonstrated.

Adenosine Triphosphatases↗
PubMedDate not supplied

An acquired interatrial fistula secondary to para-aortic abscess documented by transesophageal echocardiography.

Para-aortic ring abscess and resulting fistulous communication between adjacent structures frequently occur in prosthetic aortic valve endocarditis but are rarely diagnosed preoperatively. We report a patient who had an abscess involving the aortic-mitral intervalvular fibrosa that eroded into the interatrial septum, causing an interatrial communication with a left-to-right shunt. The abscess was detected by transthoracic echocardiography, but the fistula was only seen by the subsequent transesophageal echocardiogram. To our knowledge, this is the first report of an interatrial fistula secondary to a para-aortic valve abscess and its diagnosis preoperatively. Transesophageal echocardiography should be performed in any patient suspected to have complicated aortic endocarditis.

Abscess↗
PubMedDate not supplied

Early recognition of heart transplant rejection by backscatter analysis from serial 2D ECHOs in a heterotopic transplant model.

The acute phase of heart transplant rejection was evaluated with two-dimensional echocardiographic (2D ECHO) image analysis in a modified Mann's cervical heterotopic transplant. Serial 2D ECHO images were obtained daily, and myocardial biopsies were obtained on the day of transplant, on day 3 after transplant, and after total rejection. Brightness of serial 2D myocardial ECHO images significantly increased to day 3 after transplant, indicating increased backscatter during hyperacute rejection. Histologically this was associated with myocardial edema. These results suggest a potential noninvasive means of recognizing acute cardiac rejection. Heart transplant rejection is characterized by myocardial edema during the early stages. Myocardial edema resulting from ischemia increases the backscatter of ultrasound, which is seen as increased brightness on 2D ECHOs. Hence we hypothesized that myocardial edema observed histologically during a hyperacute rejection process can be seen on serial 2D ECHOs of the transplanted heart. Serial 2D ECHOs were obtained in five goats that had undergone a modified Mann's cervical heterotopic transplant. Image parameters were kept constant throughout each experiment. After each experiment, 2D ECHOs of a soft-tissue phantom were also recorded with the same image parameters and were used for normalizing the myocardial brightness estimated from 2D ECHO images. Visually, brightness of 2D ECHO images of all transplanted myocardia increased to day 3 after transplantation; thereafter, the brightness decreased but was still greater than on the day of transplantation. The measured mean (+/- SD) relative integrated brightness increased from 0.60 +/- 0.38 on the day of transplantation to 1.05 +/- 0.43 (p less than 0.005) on day 3 after transplantation and decreased to 0.70 +/- 0.33 (p less than 0.05) on day 7 after transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Myocardial calcification in an extremely low birth weight infant with chronic renal failure and secondary hyperparathyroidism.

Myocardial calcification has been rarely described in premature infants after myocardial infarction and myocarditis with coxsackievirus B1. In adults and older children, metastatic myocardial calcification has been reported in chronic renal failure. We report a case of myocardial calcification in a 680-gm preterm infant after a prolonged course of renal failure complicated by secondary hyperparathyroidism. Subclinical myocardial injury was evidenced by a high serum creatine phosphokinase MB band concentration, which probably provided a susceptible substrate for the deposition of calcium crystals, because the multiplication product of serum calcium and inorganic phosphorus levels transiently exceeded 75 mg x mg/100 ml, indicating serum saturation during the course of secondary hyperparathyroidism. We report this case as an unusual complication of renal immaturity in extremely low birth weight infants and an indication of a relatively intact parathyroid glandular function in them. Hypoxia, myocardial dysfunction, and renal failure are common complications in such infants, and in the presence of renal failure, the serum levels of calcium and inorganic phosphorus should be maintained below the pathologic level to avoid ectopic calcification of the tissues, including the myocardium.

Calcinosis↗