Six-month prophylaxis is cost effective in transplant patients at high risk for cytomegalovirus infection

The risk of late-onset cytomegalovirus (CMV) infection remains a concern in seronegative kidney and/or pancreas transplant recipients of seropositive organs despite the use of antiviral prophylaxis. The optimal duration of prophylaxis is unknown. We studied the cost effectiveness of 6- versus 3-mo prophylaxis with valganciclovir. A total of 222 seronegative recipients of seropositive kidney and/or pancreas transplants received valganciclovir prophylaxis for either 3 or 6 mo during two consecutive time periods. We assessed the incidence of CMV infection and disease 12 mo after completion of prophylaxis and performed cost-effectiveness analyses. The overall incidence of CMV infection and disease was 26.7% and 24.4% in the 3-mo group and 20.9% and 12.1% in the 6-mo group, respectively. Six-month prophylaxis was associated with a statistically significant reduction in risk for CMV disease (HR, 0.35; 95% CI, 0.17 to 0.72), but not infection (HR, 0.65; 95% CI, 0.37 to 1.14). Cost-effectiveness analyses showed that 6-mo prophylaxis combined with a one-time viremia determination at the end of the prophylaxis period incurred an incremental cost of $34,362 and $16,215 per case of infection and disease avoided, respectively, and $8,304 per one quality adjusted life-year gained. Sensitivity analyses supported the cost effectiveness of 6-mo prophylaxis over a wide range of valganciclovir and hospital costs, as well as variation in the incidence of CMV disease. In summary, 6-mo prophylaxis with valganciclovir combined with a one-time determination of viremia is cost effective in reducing CMV infection and disease in seronegative recipients of seropositive kidney and/or pancreas transplants.

RNA-mediated regulation of Bc1-2 and cyclin 'D' genes in human platelets

The aim of this study was to understand the RNA-mediated regulation of genes coding for Bc1-2 and cyclin 'D'. Evidence was provided that these genes are regulated by receptor-C(k)-dependent signalling in human platelets. Further experiments to resolve the mechanism through which receptor-C(k) regulates these genes revealed that receptor-C(k)-dependent signalling is involved in the cleavage of a 125-kDa protein present in endoplasmic reticulum, resulting in generation of a 47-kDa factor that has affinity for a genomic sterol regulatory element as well as the platelet mRNA pool. Based upon these findings we propose a receptor-C(k) dependent signalling pathway for the regulation of Bc1-2 and cyclin 'D' genes at the post-transcriptional level.

‘Induction of inflammatory gene expression by THP-1 macrophages cultured in normocholesterolaemic hypertensive sera and modulatory effects of green tea polyphenols’

Hypertension is a disorder controlled by multiple genes and inflammation and vascular remodelling of arteries have been implicated in pathogenesis of this disease. Green tea polyphenols (GrTPs) are rich in antioxidants and are known to inhibit inflammatory responses. A significant time-dependent increase in mRNA expression of both IL-6 and MMP-9 were observed in THP-1 macrophages when cultured in normocholesterolaemic hypertensive sera (P<0.05).

Genomic effect of vitamin 'C' and statins within human mononuclear cells involved in atherogenic process

Deregulated crosstalk within nuclear receptor/transcription factor family, comprising of peroxisome proliferator-activated receptors (PPARs) and liver X receptor-alpha (LXR-alpha), can give rise to cooperativity between lipid peroxidation and inflammation leading to atherogenic process. The present study addressed to explore the effect of statins and vitamin 'C' on transcriptional expression of genes coding for this nuclear receptor/transcription factor family within mononuclear cells revealed for the first time that both mevastatin and vitamin 'C' have common action in that they significantly downregulate the expression of PPARs (alpha, gamma) genes and upregulate LXR-alpha gene expression as compared to the control. The similar phenomenon was observed in mononuclear cells obtained from coronary heart disease (CHD) patients who were receiving atorvastatin treatment (20 mg HS). Further, the observed upregulatory effect of LXR-alpha gene expression was in conformity with the downregulatory effect of LXR-alpha on its effector gene matrix metalloproteinase-9. Based on these results, we propose that LXR-alpha-dependent signaling pathway may be a crucial target for the therapeutic intervention in human CHD, and in addition to statins, vitamin 'C' deserves a close scrutiny for the treatment of CHD.

Cholesterol-sensor initiates M. tuberculosis entry into human macrophages

Cholesterol-mediated mycobacteria entry into and survival within macrophages has added a new dimension to Tuberculosis research. The molecular mechanism through which cholesterol initiates this process is still poorly understood. The present study addressed to resolve this mechanism revealed that Mycobacterium tuberculosis possesses cholesterol-specific Receptor 'Ck'-like molecule responsible for mycobacterial entry into macrophages. Further human Receptor-Ck was found to regulate transcriptional expression of a gene that codes for Tryptophan-Aspartate containing coat (TACO) protein responsible for survival of mycobacteria within cells. Based upon these results, we propose that interaction of Receptor-Ck with cholesterol-rich membrane domains helps to create a 'Synaptic-junction' between mycobacteria and macrophage resulting in signalling events that are responsible for mycobacterium entry into and survival within macrophages.

Effect of green tea polyphenols on the genes with atherosclerotic potential

The genomics of atherosclerosis can arise as a result of cross-talk between the genes coding for the LDL-receptor (LDL-R), LXR-alpha, PPARs (alpha, gamma), CD36 and C-myc because these genes control lipid metabolism, cytokine production and cellular activity within the arterial wall. The effect of green tea polyphenols (GTPs) upon such genomics revealed their ability to down-regulate genes coding for PPAR-gamma, CD36, LXR-alpha, C-myc coupled with up-regulation of genes coding for LDL-R and PPAR-alpha at the transcriptional level. Based upon these results, it is proposed that GTPs have the inherent capacity to inhibit the development of atherosclerotic lesions.

Regulation of PPAR-gamma gene in human promyelocytic HL-60 cell line

The present study employed human promyelocytic cell line, HL-60, as an archetype model to understand the role of cholesterol receptors (Receptor-C(k) and oxysterol-specific receptor-transcription factor LxR-alpha) in the regulation of PPAR-gamma gene recognized to control cellular differentiation and apoptosis. Such a study revealed that Receptor "C(k)"-dependent signalling pathway not only regulates PPAR-gamma gene transcription but also provides ligands for the activation of this nuclear receptor superfamily of transcription factors that control hematopoiesis. Based upon these and our earlier results, we propose a molecular cross-talk pathway between cholesterol-specific cell surface Receptor-C(k) and nuclear receptors (LxR-alpha and PPAR-gamma), which may add a new dimension in the understanding and control of leukemogenesis.

Capacity of neutrophils and monocytes from human immunodeficiency virus-infected patients and healthy controls to inhibit growth of Mycobacterium bovis

We compared the differences in growth inhibition of Mycobacterium bovis by monocytes and neutrophils from human immunodeficiency virus (HIV)-infected persons (n = 12; mean CD4 count = 451/mm(3)) and healthy controls (n = 6). Phagocytes from all HIV-infected patients were incubated with or without exogenous granulocyte-macrophate colony-stimulating factor (GMCSF; 500-1000 U/mL). In two of the HIV-infected patients, phagocytes were incubated with or without interleukin (IL)-2 or IL-8 (500-1000 U/mL). Compared with that in HIV-infected patients, the reduction of M. bovis growth at 24 hours was 81% greater among monocytes and 69% greater among neutrophils from healthy controls (P =.03 and.04, respectively). Among HIV-infected patients, we noted greater mycobacterial reduction in monocytes (49%, P =.04) and neutrophils (42%, P =.05) from the early-stage patients (mean CD4 count = 760/mm(3)) compared with that in late-stage patients (mean CD4 count = 172/ mm(3)). Incubation with GM-CSF, IL-2, or IL-8 did not augment mycobactericidal activity. These findings suggest that the capacity of neutrophils and monocytes from HIV-infected patients to inhibit the growth of M. bovis is impaired, and this impairment is more pronounced in later stages of HIV infection.

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.

Molecular link between cholesterol, cytokines and atherosclerosis

Current investigation on the origin of atherosclerosis has initiated an intense debate over whether atherosclerosis results from hypercholesterolemia or an inappropriate immune response to vascular injury. Although the role of the immune system has been questioned, the overwhelming body of evidence clearly indicates that atherogenesis is initiated by the interplay between cholesterol and cellular secretion of cytokines (especially IL-6) and apolipoprotein 'E' within the arterial wall. Recent studies have revealed that cells possess two cholesterol-sensors: (a) Receptor-Ck which senses the extracellular cholesterol and initiates signalling pathway responsible for the regulation of genes involved in the cell cycle, cell death, cellular cholesterol homeostasis and cytokines including IL-6; (b) LxR alpha which senses intracellular oxysterols and controls genes involved in cell death, cellular cholesterol homeostasis and cytokine IL-8. These cholesterol sensors define the molecular mechanism responsible for cholesterol-depended regulation of cellular synthesis and secretion of cytokines (IL-6, IL-8) within arterial wall. On the basis of this mechanism, presence of cholesterol and its oxy-derivative in the modified LDL will result in transient activation/deactivation of Receptor-Ck-dependent genes which will give rise to repeated cycles of growth coupled with apoptosis leading to a situation where apoptotic-deficient cells in the arterial wall, would be selected resulting in their accumulation and formation of oligoclonal atherosclerotic plaque.

Receptor-Ck regulates giardia encystation process

The study addressed to resolve the mechanism involved in cholesterol-dependent regulation of giardia encystation process, revealed that (a) the trophozoites have the ability to express genes coding for receptor-Ck and sterol element binding protein (SREBP); (b) inhibition of cholesterol dependent activation of receptor-Ck results in the upregulation of CWP-1 gene expression leading to encystation process. Based upon these findings, we propose that receptor-Ck dependent signalling is responsible for the regulation of giardia encystation process by cholesterol.

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.

Effect of prior nucleoside use on the two-year virological response to an initial protease inhibitor regimen in HIV-infected patients

PURPOSE

This retrospective study investigates the effect of prior nucleoside (nucleoside reverse transcriptase inhibitor [NRTI]) experience on 2-year virologic response to an initial protease inhibitor-highly active antiretroviral therapy (PI-HAART) regimen.

METHOD

152 patients who started a PI (excluding saquinavir hard gel capsule [hgc] as a sole PI) with two NRTIs between January 1996 and May 1998 at two HIV treatment sites were included.

RESULTS

109 patients (71%) were NRTI experienced. 106 patients received two new NRTIs, and 32 received one new NRTI. Overall, 51% of patients had a virologic response (HIV viral load <400 copies/mL); the mean follow-up was 28 months. Virologic response was associated with the use of at least one new NRTI (relative risk [RR] 2.1; p =.031) but not with prior NRTI experience (p =.19). A complete virologic response was most likely to occur when two new NRTIs were used (RR 2.3) rather than one new NRTI (RR 1.8), but this was not significant (p =.12).

CONCLUSION

This study suggests that prior nucleoside experience is not a key predictor of 2-year virologic response in patients who receive at least one new NRTI in an initial PI-HAART regimen.

Receptor-Ck regulates membrane-bound 125 kDa protein having affinity for genomic sterol regulatory sequence

The study addressed, to resolve the role of Receptor-Ck activation in the proteolytic maturation of 125 kDa (membrane bound) sterol regulatory element binding protein (SREBP), revealed that Receptor-Ck dependent signalling is not only responsible for the proteoloytic cleavage of this 125 kDa SREBP resulting in the generation of an active 47 kDa factor but also Receptor-Ck protein has high binding affinity for both 125 kDa SREBP as well as its cleaved 47 kDa product. Based upon these coupled with our earlier findings, we propose that Receptor-Ck may be regulating genes, have sterol regulatory element (SRE) in their promoter region, through the proteolytic maturation of 125 kDa SREBP into an active 47 kDa transcription factor.

Expression of receptor-Ck and SREBP genes in mononuclear cells from acute leukemia patients

We have recently shown that Receptor-Ck regulated genes, involved in cellular growth and death through a transcriptional factor (SREBP) which has affinity for sterol regulatory element (SRE) present in the promoter region of these genes. The present study revealed that blasts, derived from both ALL and AML patients, were unable to express SREBP gene product although they had the capacity to express Receptor-Ck gene product. These results which depict defective Receptor-Ck-dependent signalling are in conformity with our previous results which showed that lymphocytes from CML patients as well as other human leukemic cell lines are unable to express gene coding for Receptor-Ck leading again to a state of impaired Receptor-Ck-dependent signalling. On the basis of these results, we propose that deregulated Receptor-Ck-dependent signalling may have an important role in leukemogenesis.