Characterization of PO1, a new peptide ligand of the apamin-sensitive Ca2+ activated K+ channel

A new peptide ligand of the small conductance Ca²⁺ activated K⁺ channels has been purified from the venom (obtained by manual rather than electrical stimulation of the scorpion Androctonus mauretanicus mauretanicus), by following the inhibition of the ¹²⁵I-apamin binding to its receptor on rat brain synaptosomes. Only one step on a C₁₈ reversed-phase high-performance liquid chromatography column was necessary to obtain PO1. Its K_0.5 for the apamin binding site was 100 nM. The amino acid sequence of PO1 is different from those of leiurotoxin and PO5. For the first time the same peptide was also purified from the venoms of two other species of North African scorpions, Androctonus austmlis and Buthus occitanus tunetanus. PO1 was chemically synthesized by the solid-phase technique and fully characterized. A model of PO1 was constructed by amino acid replacement using PO5 nuclear magnetic resonance studies as the starting model. Structure-activity relationships between these toxins and their receptor are discussed.     

Efficacy of vitamin E in children with immunotolerant-phase chronic hepatitis B infection

BACKGROUND: The purpose of the present paper was to investigate the efficacy of vitamin E in children with immunotolerant-phase chronic hepatitis B virus (CHB) infection. METHODS: Fifty-eight immunotolerant children were prospectively and randomly recruited into two groups. Group 1 (study group) included 30 patients who received vitamin E at a dose of 100 mg/day throughout 3 months; group 2 (control group) contained 28 patients who did not receive any medication. Comparison of serological, virologic, and biochemical response ratios were done at the end of the therapy and after 6 months of vitamin E discontinuation. RESULTS: Mean alanine transaminase (ALT) values in group 1 at the beginning of the therapy, 3 months after the therapy initiation and 6 months after discontinuation were 30.4 +/- 7.3 IU/L, 31.3 +/- 7.8 IU/L and 32.1 +/- 8.5 IU/L, respectively. The mean hepatitis B virus (HBV)-DNA load of group 1 at onset, and at the third and ninth months of the treatment were 3106 +/- 718 pg/mL, 3530 +/- 137 pg/mL and 3364 +/- 1246 pg/mL, respectively. These changes in both ALT and HBV-DNA values did not reach significant levels (P > 0.05). In group 2, mean ALT values at the beginning of therapy, and at the third and ninth months were 28.0 +/- 1.8 IU/L, 34.6 +/- 8.1 IU/L, and 34.1 +/- 7.0 IU/L, respectively (P > 0.05), and mean viral load of HBV-DNA was 4227 +/- 1435 pg/mL, 3368 +/- 2673 pg/mL, and 3018 +/- 2814 pg/mL, respectively (P > 0.05). There was no statistically significant difference between group 1 and group 2 at the third and ninth months in the mean ALT values and viral load of HBV-DNA (P > 0.05). Hepatitis B s antigen and hepatitis B e antigen clearance or hepatitis B s antibody and hepatitis B e antibody seroconversion were not observed in either group. CONCLUSION: As a first study investigating the effect of vitamin E in children with immunotolerant CHB infection, no beneficial effect could be demonstrated. Different immunomodulator protocols should be considered for future investigations.