Functional proteomics of receptor-Ck in the developmental stages of human atherosclerotic arterial wall.

BACKGROUND: The study was undertaken to understand the relationship between the functional proteomics of receptor-Ck and developmental stages of human atherosclerotic aortic wall. METHODS AND RESULTS: Gene expression study of 25 aortas was undertaken and the results revealed a gradual increase in receptor-Ck gene expression paralleled by the regulatory response of its effector genes coding for sterol response element-binding protein, p27, cyclin D, interleukin-6 and CD40 from a normal to atherosclerotic arterial wall (viz. fatty streak and fibrofatty/fibrous plaque). CONCLUSIONS: Based upon this and our earlier studies, we propose that cholesterol-specific receptor-Ck-dependent gene regulation may be of crucial importance in atherogenesis.

Expression of Bcl2 proto-oncogene in primary tumors of the central nervous system.

The present study was addressed to find out the expression of Bcl2 proto-oncogene in tumor tissues derived from 25 patients with primary central nervous system tumors. Brain parenchyma in 8 cases, with deeply located tumor, was also examined for Bcl2 expression which served as control. Both benign and malignant tumors (confirmed by histopathological examination) expressed Bcl2 gene product. Tumors exhibited 2-6 fold increase in Bcl2 expression as compared to the normal parenchyma adjacent to some of these tumors studied. However, no correlation was found between the histopathological types of tumor, glial fibrillary acidic protein positivity and degree of Bcl2 expression. Based on this study, we propose that the overexpression of Bcl2 gene product found in primary CNS tumors may be an important molecular event which is known to make the various types of tumor resistant to chemotherapy or radiotherapy.

Expression and functional activity of receptor-Ck in mononuclear cells of a homozygous hypercholesterolemic family.

The study was addressed to explore the expression and functional activity of a novel cholesterol-specific cell surface receptor-Ck in a typical homozygous familial hypercholesterolemic family. Functional activity of receptor-Ck was characterized by its ability to downregulate Bcl-2 gene expression through a 47 kDa factor having an affinity for the sterol-regulatory element in the promoter region of this gene. The result of such a study revealed normal expression and functional activity of receptor-Ck accompanied by a lack of Apolipoprotein B-specific low-density lipoprotein receptor gene expression in the mononuclear cells derived from these patients. On the basis of these results, it is tempting to speculate that receptor-Ck may be involved in the maintenance of cellular cholesterol homeostasis observed in homozygous familial hypercholesterolemic patients.

Clinical manifestations and management of pediatric HIV infection.

HIV infection has emerged as a colossal problem with epidemic proportions. According to an estimate from UNAIDS about 36.1 million people all over the world are infected at present. In India about 3.5 million people are infected. The infection has evolved into phase II process of disease evolution, spreading from high-risk population to the general population. The antenatal HIV seropositivity has shown a steady increase from 0.1% to 2% in some tertiary care hospitals in Mumbai. Pediatric HIV infection presents with diverse clinical manifestations. In developing countries like India, diagnosis of infection during first year of life in perinatally exposed infants poses a problem due to lack of easy accessibility and increased cost of diagnostic facilities like HIV-PCR, CD4/CD8 counts and viral cultures. Moreover, lack of adequate drugs and exorbitant cost of sustaining antiretroviral therapy complicates the management issues. An assortment of antiretovirals is available in USA and other developed countries. In India drugs like zidovudine, lamivudine, stavudine, nevirapine and indinavir are available and are used in symptomatic patients. CDC has defined definite treatment guidelines for pediatric population recently. These guidelines need to be modified in our set up. At the present juncture in India the emphasis remains on the prevention and treatment of opportunistic infections like tuberculosis and pneumocystis carinii and on prevention of perinatal transmission with zidovudine. This brief review deals with various clinical manifestations as relevant in a developing country like India and recent advances in antiretroviral therapy.

Molecular basis of cholesterol feedback lesion in CNS tumours.

An important feature of malignant transformation of tumours is the loss of cholesterol feedback inhibition mechanism (cholesterol-feedback lesion) that regulates mevalonate pathway recognized to play a crucial role in cellular growth, death and differentiation. Recently, it was shown that Receptor-C(k)-dependent signalling regulates genes involved in maintaining cellular cholesterol homeostasis through a transcription factor sterol response element binding protein (SREBP) having affinity for sterol regulatory element (SRE) present in the promoter region of these genes. The present study revealed that CNS tumours exhibit overexpression of Receptor-C(k) gene product which was accompanied by their inability to express SREBP gene product and this phenomenon has the inherent capacity to initiate the cholesterol feedback lesion in these tumours. Based upon these and our earlier studies, we propose for the first time that this loss of cholesterol feedback control may be responsible for the initiation of these tumours.

Genetic polymorphism in muscle biopsies of Duchenne and Becker muscular dystrophy patients.

Duchenne muscular dystrophy (DMD), with an incidence of one in 3500 male new borns, and its milder variant, Becker muscular dystrophy (BMD), are allelic X-linked recessive disorders, caused by mutations in the gene coding for dystrophin, a 427 kD cytoskeleton protein. There are no available molecular markers to differentiate these two. The purpose of this study was to study genetic polymorphism in muscular dystrophy and explore its potential in discriminating these two allelic forms of the disease. The results revealed unambiguously the presence of three transcripts : 598bp, 849bp and 1583bp long which are selectively expressed in the muscles afflicted with muscular dystrophy as compared to the normal muscle. 1583bp gene transcript was conspicuously present in the muscle tissues of both DMD and BMD patients whereas 598bp and 849bp long transcripts were exclusively present in DMD but not in BMD patients or normal human subjects. These gene transcripts had no sequence homology with dystrophin gene and these were also present in the families belonging to DMD and BMD patients. These results point to the fact that based upon the selective expression of these three gene transcripts, one could not only differentiate between DMD and BMD diseases at the molecular level, but also between normal and dystrophic muscle. Further, these findings also reveal that apart from dystrophin gene, these gene transcripts may also be responsible for the differential progression of DMD/BMD phenotype.

Lack of expression of c-myc oncogene in peripheral blood mononuclear cells of patients with active rheumatoid arthritis.

We looked for the expression of c-myc oncogene, one of the genes that enhance apoptosis, in 11 patients with active rheumatoid arthritis (RA) along with five patients with osteoarthritis (OA) knee as disease controls and six healthy volunteers. A dot-blot assay using a probe specific for c-myc oncogene was performed on total RNA obtained from peripheral blood mononuclear cells. There was no expression in patients with active RA and healthy volunteers. One patient with OA expressed c-myc. Lack of expression of c-myc suggests that in active RA circulating lymphocytes are not in the replicative phase despite ongoing disease activity.

Effect of anticalmodulin and antitubulin on LDL-receptor synthesis in aortic smooth muscle cells cultured in vitro.

Effect of trifluoperazine and colchicine on LDL-receptor synthesis in smooth muscle cells exposed to hypercholesterolemic medium in vitro have been studied. While trifluoperazine at 25 microM concentration caused stimulation of LDL-receptor synthesis, colchicine acted as a dose-dependent inhibitor of LDL-receptor synthesis. Thus calmodulin down regulates LDL-receptor synthesis independent of microtubular involvement.

Preventive effect of trifluoperazine on atherosclerosis induced by cholesterol & adrenaline in rabbits.

Studies on the preventive role of trifluoperazine on cholesterol and adrenaline-induced experimental atherosclerosis in rabbits, revealed that trifluoperazine completely prevented the development of atherosclerotic lesions in both the aorta and coronary arteries of animals administered atherogenic diet and adrenaline (im) despite the fact that this drug had no significant effect on the elevated serum lipid profile induced by atherogenic diet. These findings confirm earlier observations of the authors that trifluoperazine has an inherent capacity to prevent atherogenesis.