[Hepatitis C epidemiology at a general hospital center. Management and natural history as a function of the manner of identification]. / Epidémiologie de l'hépatite C dans un centre hospitalier général. Prise en charge et histoire naturelle en fonction du mode de découverte.

OBJECTIVES: To study the epidemiological characteristics of patients with chronic hepatitis C virus followed in a primary referral hospital and the clinical influence of "systematic screening" defined as the screening of patients without symptoms and with known risk factors of hepatitis C (past transfusion, past or present intravenous drug use, haemodialysis) on the natural history and treatment of chronic hepatitis C virus. METHODS: The files of 311 consecutive patients who screened positive for anti-hepatitis C virus and were seen at the primary referral hospital, Creil, from January 1992 to February 1996, were analyzed. RESULTS: Patients who underwent "systematic screening" were younger with a shorter duration of infection. They were more often intravenous drug addicts and had lower alanine aminotransferase activity and Knodell scores than patients who underwent screening during "a diagnostic procedure", because of symptoms and/or abnormal liver biochemistry. Increased age at contamination and alcohol consumption of more than 40 g per day was associated with an increased risk of cirrhosis while patients who underwent "systematic screening" had a lower risk of cirrhosis and higher survival rate. Interferon therapy was attempted less often in anti-hepatitis C virus positive patients from "systematic screening" programs. CONCLUSIONS: Anti-hepatitis C virus positive patients from "systematic screening" programs had a benign disease and were rarely treated with interferon compared to anti-hepatitis C virus positive patients diagnosed during a "diagnostic procedure".

[Hepatitis B: epidemiology, natural history, biology, treatment monitoring]. / Hépatite B: épidémiologie, histoire naturelle, biologie, surveillance du traitement.

Hepatitis B virus (HBV) infection is a worldwide public health problem. In France, 150,000 individuals are infected with the HBV. Although many are asymptomatic carriers, about 30% have chronic hepatitis, a condition associated with a risk of cirrhosis and hepatocellular carcinoma. Antiviral treatments, most notably interferon alpha, probably modify the natural history of hepatitis B, decreasing the risk of hepatocellular carcinoma and increasing survival. Nucleoside analogs, particularly lamivudine, have also demonstrated potent antiviral activity, which should however be weighed against the increasing risk over time of mutation development in the YMDD region of the DNA polymerase reverse transcriptase. Antiviral therapy monitoring should include clinical safety evaluations and periodic laboratory tests including blood cell counts, transaminase activities, and serum DNA levels. The improving results provided by antiviral drugs should not deflect attention away from the importance of large-scale hepatitis B immunization of neonates, which has been shown to decrease the incidence of hepatocellular carcinoma in areas with high levels of hepatitis B endemicity.

Retention in field-flow fractionation with a moderate nonuniformity in the field force.

In some field-flow fractionation (FFF) techniques, the basic analyte-field interaction parameter, λ, is not constant but varies within the channel cross section as a result of the nonuniformity of the force exerted by the field on the analyte. This is the case, for instance, in thermal FFF, because of the temperature dependence of the relevant physicochemical transport parameters. To account for this effect, a new FFF retention model is developed, allowing a linear variation of λ from the accumulation to the depletion wall, which is assumed to describe correctly moderate nonuniformity in λ in the vicinity of the accumulation wall. A methodology for sample characterization on the basis of this model is proposed. It associates λ(app), the apparent λ value derived from the retention ratio by means of the classical retention model, with a specific distance from the accumulation wall. An empirical relationship between that distance and λ(app) is derived. In the high retention limit, it is found that this specific distance is not equal, as sometimes intuitively believed, to the mean distance of the molecule or particle cloud to the accumulation wall but is approximately equal to twice this mean distance. The validity of the proposed approach is checked.