The virological aspects of hepatitis B.

Human hepatitis B virus (HBV) is a hepatotropic virus that is responsible for a significant burden of disease, causing liver disease and hepatocellular carcinoma. It is a small DNA virus with a replication strategy that is similar to that of a retrovirus. HBV is prone to mutagenesis and under the influence of diverse selection pressures, has evolved into a pool of quasispecies, genotypes and mutants, which confers a significant survival advantage. The genome is small, circular, and compact but has a complex replication strategy. The viral life cycle involves the formation of a covalently closed circular DNA (cccDNA), which is organized into a minichromosome that is the template for the synthesis of viral mRNA. HBV DNA (double-stranded linear form) can also integrate into the host genome, ensuring lifelong persistence of the virus. To date, despite great advances in therapeutics, once HBV is chronically established, it is incurable. This is by virtue of many aspects of its virological structure and viral life cycle. In this review, we aim to discuss important aspects of the virology of HBV with a focus on clinical implications.

Increased coated-platelet levels in chronic haemodialysis patients.

AIM: To determine if levels of coated-platelets, which are potentially pro-thrombotic, are increased in end-stage renal disease patients on haemodialysis, a condition associated with high cardiovascular disease risk. METHODS: In a cross-sectional observational study, coated-platelet levels were measured by flow cytometry in 25 end-stage renal failure haemodialysis patients and 25 controls without renal disease. Associations between coated-platelet levels and clinical and biochemical factors relevant to renal and cardiovascular disease were evaluated. RESULTS: Mean +/- SD coated-platelet levels were higher in the dialysis group than in the control group (39.3+/-14.3% vs 30.9+/-10.3%, P=0.02). The number of subjects with high coated-platelet levels (>40%) was larger in the dialysis than in the control group (13/25 vs 4/25, chi(2) test, P=0.007). On univariate analysis, coated-platelet levels correlated with serum C-reactive protein levels in renal failure (r=0.47, P=0.02) and inversely with white cell count in the control group (r= -0.60, P=0.001). Coated-platelet levels were higher in dialysis patients reporting alcohol abstinence than among those reporting 'social' drinking (44.3+/-12.6 vs 28.8+/-13.5%, P=0.01). Age, gender, body weight, smoking, diabetes, lipid levels and lipid-lowering drugs were not associated with coated-platelet levels (all P>0.05). CONCLUSION: Coated-platelet levels are increased in haemodialysis patients relative to subjects with normal renal function, and are related to inflammation and alcohol abstinence. Other vascular risk factors, such as smoking, lipids and diabetes, were not related to coated-platelet levels. Coated-platelets may be implicated in the increased thrombosis and vascular risk in end-stage renal disease.