Cross-resistance testing of antihepadnaviral compounds using novel recombinant baculoviruses which encode drug-resistant strains of hepatitis B virus

Long-term nucleoside analog therapy for hepatitis B virus (HBV)-related disease frequently results in the selection of mutant HBV strains that are resistant to therapy. Molecular studies of such drug-resistant variants are clearly warranted but have been difficult to do because of the lack of convenient and reliable in vitro culture systems for HBV. We previously developed a novel in vitro system for studying HBV replication that relies on the use of recombinant baculoviruses to deliver greater than unit length copies of the HBV genome to HepG2 cells. High levels of HBV replication can be achieved in this system, which has recently been used to assess the effects of lamivudine on HBV replication and covalently closed circular DNA accumulation. The further development of this novel system and its application to determine the cross-resistance profiles of drug-resistant HBV strains are described here. For these studies, novel recombinant HBV baculoviruses which encoded the L526M, M550I, and L526M M550V drug resistance mutations were generated and used to examine the effects of these substitutions on viral sensitivity to lamivudine, penciclovir (the active form of famciclovir), and adefovir, three compounds of clinical importance. The following observations were made: (i) the L526M mutation confers resistance to penciclovir and partial resistance to lamivudine, (ii) the YMDD mutations M550I and L526M M550V confer high levels of resistance to lamivudine and penciclovir, and (iii) adefovir is active against each of these mutants. These findings are supported by the limited amount of clinical data currently available and confirm the utility of the HBV-baculovirus system as an in vitro tool for the molecular characterization of clinically significant HBV strains.     

Stimulation of eosinophil production in vitro by eosinophilopoietin and spleen-cell-derived eosinophil growth-stimulating factor

Eosinophilopoietin (EPP) was previously characterized by the ability to stimulate eosinophil production in vivo, but these studies could not ascertain whether EPP had a direct effect on the bone marrow or acted indirectly by causing release of eosinophilopoietic activity by other tissues. The present studies demonstrate that EPP stimulates eosinophil growth in liquid culture of mouse bone marrow in vitro. The timing of stimulation by EPP in vivo and in vitro were parallel, with maximal eosinophil growth after 48 hr. Moreover, EPP appears similar to, and possible identical with, the eosinophil growth-stimulating substance (EO-GSF) released by antigenic stimulation of immune nonadherent spleen cells. Both EPP and EO-GSF are of low molecular weight, both produce stimulation of eosinophil growth with identical kinetics, and both produced similar dose-response curves in the liquid culture system.     

Impaired cell volume regulation in intestinal crypt epithelia of cystic fibrosis mice.

Cystic fibrosis is a disease characterized by abnormalities in the epithelia of the lungs, intestine, salivary and sweat glands, liver, and reproductive systems, often as a result of inadequate hydration of their secretions. The primary defect in cystic fibrosis is the altered activity of a cAMP-activated Cl- channel, the cystic fibrosis transmembrane conductance regulator (CFTR) channel. However, it is not clear how a defect in the CFTR Cl- channel function leads to the observed pathological changes. Although much is known about the structural properties and regulation of the CFTR, little is known of its relationship to cellular functions other than the cAMP-dependent Cl- secretion. Here we report that cell volume regulation after hypotonic challenge is also defective in intestinal crypt epithelial cells isolated from CFTR -/- mutant mice. Moreover, the impairment of the regulatory volume decrease in CFTR -/- crypts appears to be related to the inability of a K+ conductance to provide a pathway for the exit of this cation during the volume adjustments. This provides evidence that the lack of CFTR protein may have additional consequences for the cellular function other than the abnormal cAMP-mediated Cl- secretion.     

Severe pulmonary hypertension and multiple left coronary arterial fistulas in association with congenital hepatic fibrosis.

Multiple fistulous communications between the left anterior descending coronary artery and the left ventricle were found in a 55 year old woman with congenital hepatic fibrosis presenting with breathlessness. At cardiac catheterisation severe pulmonary hypertension was also found. In view of the persistent hypoprothrombinaemia, severe thrombocytopenia, and the multiple fistulas the risk of operation was thought to be unacceptable and she continues on medical treatment.     

Shape response of human erythrocytes to altered cell pH

Alteration of red blood cell (RBC) pH produces stomatocytosis (at low pH) and echinocytosis (at high pH). Cell shrinkage potentiates high pH echinocytosis, but shrinkage alone does not cause echinocytosis. Mechanisms for these shape changes have not been described. In this study, measured dependence of RBC shape on cell pH was nonlinear, with a broad pH range in which normal discoid shape was maintained. Transbilayer distribution of phosphatidylcholine and phosphatidylserine, measured by back-extraction of radiolabeled lipid, was the same in control and altered pH cells. Possible roles of pH- titratable inner monolayer phospholipids were examined by assessing pH- dependent shape in cells in which their levels had been perturbed. In metabolically depleted cells and calcium-treated cells, which have altered levels of phosphatidic acid, phosphatidylinositol-4-phosphate, and/or phosphatidylinositol-4,5-bisphosphate, low cell pH was stomatocytogenic and high cell pH was echinocytogenic, as in control cells. Thus, neither change in membrane lipid asymmetry nor normal levels of the pH-titratable inner monolayer lipids is necessary for cell pH-mediated shape change.     

宁夏贝母化学成分的研究

从宁夏贝母(Frdillapia taipaiensis P. Y. Li var. ningxiaensis Y. K. Yang et. J. K. Wu)的鳞茎中分得六个异甾体生物碱成分,鉴定为宁贝素(taipaienine,Ⅰ)、川贝酮(chuanbeinone,Ⅱ)、西贝素(imperialine,Ⅲ)、贝母乙素(verticinone,Ⅳ)、贝母辛(peimissine,Ⅴ)和异贝母甲素(isoverticine,Ⅵ).其中T为一新C-去甲-D-高甾生物碱。应用波谱分析(IR,MS,¹HNMR和¹³CNMR)等确定了它们的化学结构。