Opsonophagocytosis versus Complement Bactericidal Killing as Effectors following <Emphasis Type="Italic">Neisseria meningitidis</Emphasis> Group C Vaccination

Background: Opsonophagocytosis and complement-mediated Neisseria meningitidis killing after vaccination were investigated. Methods: Twelve seronegative healthy volunteers received one dose of polysaccharide A/C vaccine and were followed for 3 years. Ex vivo serum killing rates with polymorphonuclear cells (PMN) and/or complement were performed at 0, 1.5, 6, 12, 18, 24, 30 and 36 months. Results: High mean total and median bactericidal antibodies were detected over time in all subjects. Considerable reduction of the initial inoculum was obtained only in the presence of complement, with or without PMN (with significant differences compared to curves without complement) a long time after vaccination. Conclusion: PMN did not increase post-vaccination bacterial killing, suggesting that antibody complement-mediated killing, and not opsonophagocytosis, is the main immune effector of the vaccine protection against N. meningitidis. Received: July 15, 2002 · Revision accepted: November 4, 2002 J. Prieto (corresponding author)     

Improved LC method to determine ivermectin in plasma

A simple, rapid and sensitive high-performance liquid chromatographic (HPLC) method has been developed to quantify Ivermectin (IVM) in plasma using an isocratic system with fluorescence detection. The method included a fast liquid phase extraction using cold methanol. HPLC separation was carried out by reversed phase chromatography with a mobile phase composed of methanol:acetonitrile:water with 0.2% acetic acid (45:50:5 v/v/v), pumped at flow rate of 2 ml min(-1). Fluorescence detection was performed at 365 nm (excitation) and 475 nm (emission). The calibration curve for IVM was linear from 0.25 to 100 ng ml(-1). The validation method yielded good results regarding linearity, precision, accuracy, specificity and recoveries. The values of the limit of detection (LOD) and limit of quantification (LOQ) were 0.032 and 0.167 ng ml(-1), respectively.     

Effect of amphiphilic surfactant agents on the gastrointestinal absorption of albendazole in cattle

Albendazole (ABZ) is a widely used broad-spectrum benzimidazole (BZD) anthelmintic. Low hydrosolubility and poor/erratic gastrointestinal (GI) absorption play against the systemic availability and resultant clinical efficacy of BZD compounds. Different strategies are currently investigated to improve their bioavailability and efficacy in different animal species and humans. Surfactant agents facilitate dissolution of lipophilic drugs and increase membrane permeability. The influence of amphiphilic surfactants on the pattern of absorption and systemic availability of ABZ and its metabolites in cattle was characterized in the current trial. Twenty (20) parasite-free Holstein calves (100-120 kg) were randomly allocated into four groups and treated intraruminally (10 mg/kg) using one of the following ABZ suspensions: control without surfactant (75/25 dimetyl sulphoxide/saline solution) (group A), 5 mM sodium taurocholate (STC) in saline solution (group B), 8.27 mM sodium lauryl sulphate (SLS) in saline solution (group C) and a commercial formulation (Valbazen((R)), Pfizer Inc. SA) (group D). Jugular blood samples were taken over 72 h post-treatment and plasma analysed by HPLC. Albendazole sulphoxide (ABZSO) and sulphone were the metabolites found in plasma. STC did not affect ABZ absorption while increased ABZSO peak plasma concentration (C(max)) (158% higher, P<0.001) was observed following co-administration of ABZ plus SLS, compared to the control group without surfactant. ABZSO plasma availability was significantly greater after the ABZ-SLS (164%) co-administration compared to that obtained in the control group without surfactant. A similar ABZSO plasma availability was obtained following the treatments with the ABZ-SLS and the commercially available formulation. SLS-mediated enhanced dissolution and absorption of ABZ accounted for the observed increased systemic availability of the active ABZSO metabolite in cattle. These results should be considered among strategies to improve the use of BZD anthelmintics.     

Human herpesvirus-6 has no apparent influence on course of HCV hepatitis,but may complicate HBV hepatitis and alcoholic liver disease. A pilot study

Human herpesvirus-6 (HHV-6) is a widespread virus with occasional reactivation and a potential hepatotropism. The present study was undertaken to investigate the frequency of HHV-6 reactivation in viral (HCV, HBV) and alcoholic liver diseases and its implication for the course of the primary disease. Serological and immunohistochemical tests were done to document viral activity, hepatocellular apoptosis or proliferation, and autoantibody formation. While the course of HCV remains apparently uninfluenced by HHV-6, HBV hepatitis and alcoholic liver disease show a higher incidence of autoantibody formation if HHV-6 is present. The data of this pilot study warrant more extensive investigations of the clinical pathology of HHV-6 in liver diseases.