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Biomedical subjects

A Sivaraman

Publications and source records attributed to A Sivaraman.

At least 19 recordsLinked to original sources
PubMed2005

Cellular destruction following transmyocardial laser revascularization (TMR).

During transmyocardial revascularization, cellular destruction of cardiomyocytes occurs as a result of the high-energy laser. However, the features of myocardial cellular destruction are unclear. The present study was undertaken to examine the structural characteristics of cell death in the myocardium following transmyocardial revascularization. Myocardial specimens from 3 male patients who had died within 11 days following laser revascularization were collected within 1 h of death and were analyzed by immunohistochemistry and electron microscopy. For immunohistochemistry, antibodies to pro-apoptotic proteins CPP32 and BAX were used. Immunohistochemical examination demonstrated the presence of cells expressing both CPP32 and BAX along the laser channel. Electron microscopic analysis revealed that the lining surface of laser channels consisted of condensed acellular debris and dead cells. No endothelialization of channels was noted. The lumen of laser channels were surrounded by a rim of acellular debris with several outer concentric rims of cardiomyocytes showing features of cellular destruction. The present study identified features of both necrotic and apoptotic cellular death following laser revascularization.

Adult↗
PubMed2005

A microscale in vitro physiological model of the liver: predictive screens for drug metabolism and enzyme induction.

In vitro models of the liver using isolated primary hepatocytes have been used as screens for measuring the metabolism, toxicity and efficacy of xenobiotics, for studying hepatocyte proliferation, and as bioartificial liver support systems. Yet, primary isolated hepatocytes rapidly lose liver specific functions when maintained under standard in vitro cell culture conditions. Many modifications to conventional culture methods have been developed to foster retention of hepatocyte function. Still, not all of the important functions -- especially the biotransformation functions of the liver -- can as yet be replicated at desired levels, prompting continued development of new culture systems. In the first part of this article, we review primary hepatocyte in vitro systems used in metabolism and enzyme induction studies. We then describe a scalable microreactor system that fosters development of 3D-perfused micro-tissue units and show that primary rat cells cultured in this system are substantially closer to native liver compared to cells cultured by other in vitro methods, as assessed by a broad spectrum of gene expression, protein expression and biochemical activity metrics. These results provide a foundation for extension of this culture model to other applications in drug discovery -- as a model to study drug-drug interactions, as a model for the assessment of acute and chronic liver toxicity arising from exposure to drugs or environmental agents; and as a disease model for the study of viral hepatitis infection and cancer metastasis.

Animals↗
PubMed2001

Sclerosing mediastinitis caused by Aspergillus terreus.

A case of Aspergillus terreus causing sclerosing mediastinitis which presented with symptoms of cardiorespiratory compromise and compressive myelopathy is described. The diagnosis was established by culturing and isolating the fungus in pure culture from the tissue and was also confirmed by demonstration of sepcific precipitating antibodies against Aspergillus terreus in patient's serum.

Adult↗
PubMed2001

Cardiac pathology of permanent pacemaker implementation.

The cardiac findings in five cases of permanent pacemaker implantation seen at autopsy in a three-year period is reported. Implantation was done for complete heart block in four patients and sick sinus syndrome in one. The periods of implantation ranged from seven days to four years. The common findings were right sided valvar and mural bland thrombus formation. Additional findings included superior vena caval thrombosis, endocardial 'tunnel' formation for the pacing wires, perforation of the tricuspid leaflet and a gross morphology similar to that seen in right sided endomyocardial fibrosis.

Autopsy↗
PubMed2000

Isolated right ventricular infarction.

Rare occurrence of isolated right ventricular infarction is reported in four patients, three of whom were elderly. The causes of infarction were due to pulmonary thromboembolism and dissection of non-dominant right coronary artery. None of the hearts had right ventricular hypertrophy and significant coronary atherosclerosis.

Adult↗
PubMed2000

Intrapericardial teratoma--a report of two cases.

Two rare cases of intra-pericardial teratoma in infants are reported. The presenting symptoms were either due to pericardial effusion and cardiac tamponade or due to compression of the tracheo-bronchial tree. The tumors were well encapsulated and were attached to the ascending aorta. Histologically, they were composed of derivatives of the three germ cell layers.

Fatal Outcome↗
PubMed1999

Neonatal candidial endocarditis--a rare manifestation of systemic candidiasis.

Infective candidial endocarditis in four premature neonates is reported. These occurred as a complication of systemic candidiasis. Vegetations were present on the right side of the heart in two cases and both sides in the other two. Diagnosis requires a high degree of clinical suspicion. Mortality rate is high despite appropriate therapy.

Candidiasis↗
PubMed1997

Pulmonary carcinomatous arteriopathy--a rare cause of dyspnoea and pulmonary hypertension.

Pulmonary carcinomatous arteriopathy was seen at autopsy in three patients who presented with sub-acute cor pulmonale. All had adenocarcinomas of unknown origin. The arteries and arterioles showed fresh and organizing thrombi with narrowing or occlusion. Large muscular arteries also showed tumour cells within the thrombi. Lymphangitis carcinomatosis was also present to a variable extent.

Adenocarcinoma↗
PubMed1996

Right-ventricular fibroma presenting as tricuspid stenosis--a case report.

A male child presented with suspicion of tricuspid stenosis. Echocardiography revealed the presence of a mass arising from the free wall of the right ventricle and causing right-ventricular inflow obstruction but not involving the tricuspid valve. The tumour was excised via right ventriculotomy using cardiopulmonary bypass, resulting in survival and a satisfactory clinical course. Histological examination showed the tumour to be a fibroma. Tricuspid stenosis is an unusual presentation of right ventricular fibroma. Careful examination is essential to early diagnosis of cardiac fibromas, particularly in children with unexplained cardiac problems. Echocardiography is still a good method for confirmation of the diagnosis and for follow-up. In view of the unknown natural history of cardiac fibroma, surgical excision should be undertaken. Early detection and prompt excision results in immediate and complete relief of symptoms and prolongs the life span.

Child, Preschool↗
PubMed1996

Coronary artery-intramyocardial sinusoid communication in a case of pulmonary atresia with intact ventricular septum.

Intramyocardial sinusoid--coronary artery fistulous communications are well established channels in pulmonary atresia with intact ventricular septum. Angiographically flow can be demonstrated from the right ventricular cavity into the coronary arteries. We have histologically demonstrated such a communication in a case of pulmonary atresia with intact septum.

Coronary Vessel Anomalies↗
PubMed1995

Balloon mitral valvotomy: an autopsy study.

The autopsy findings in 20 patients who died following percutaneous balloon mitral valvotomy are reported. The procedure was attempted in 508 patients. In 17 of the 20 patients, balloon mitral valvotomy was attempted as a salvage procedure. Ten patients died in the immediate post valvotomy period (within 24 h), seven died within a week and three between 1 to 3 months. In 13 patients, the balloon valvotomy successfully opened out one or both commissures. Interatrial septostomy defects created by the transeptal catheter could be identified in 19 of 20 heart specimens. The size of the defects ranged from small (5 mm) openings to large (15 mm) defects especially with double balloon. Marked mitral valvar thickening with nodular calcification was observed in 16 cases. Significant complications leading to mortality included cardiac tamponade (five cases) due to left ventricle apical perforation (3/5 cases). Mitral valve damage in the form of leaflet tears, chordal rupture and long splits in five cases resulted in significant mitral regurgitation. The leaflet tears resulted in detachment of part of the leaflet from the annulus. A late complication noted was infective endocarditis. Associated pulmonary tuberculosis, chronic obstructive pulmonary disease, respiratory infections and multivalvar diseases also contributed to mortality.

Adolescent↗
PubMed1994

Isolated left-sided intracardiac fungal mass.

A left-sided fungal (Candidial) intracardiac mass was found at autopsy in a 38-day premature infant with hydrops foetalis. Such a manifestation of systemic candidiasis has not been reported previously.

Candidiasis↗