Suppression of ceramide-induced cell death by hepatitis C virus core protein

The hepatitis C virus (HCV) core protein is believed to be one of viral proteins that are capable of preventing virus-infected cell death upon various stimuli. But, the effect of the HCV core protein on apoptosis that is induced by various stimuli is contradictory. We examined the possibility that the HCV core protein affects the ceramide-induced cell death in cells expressing the HCV core protein through the sphingomyelin pathway. Cell death that is induced by C(2)-ceramide and bacterial sphingomyelinase was analyzed in 293 cells that constitutively expressed the HCV core protein and compared with 293 cells that were stably transfected only with the expression vector. The HCV core protein inhibited the cell death that was induced by these reagents. The protective effects of the HCV core protein on ceramide-induced cell death were reflected by the reduced expression of p21(WAF1/Cip1/Sid1) and the sustained expression of the Bcl-2 protein in the HCV core-expressing cells with respect to the vector-transfected cells. These results suggest that the HCV core protein in 293 cells plays a role in the modulation of the apoptotic response that is induced by ceramide. Also, the ability of the HCV core protein to suppress apoptosis might have important implications in understanding the pathogenesis of the HCV infection.     

Comparison of PERV genomic locations between Asian and European pigs

Xenotransplantation from pigs provides a possible solution to the shortage of human organs for allotransplantation. Porcine endogenous retroviruses (PERVs) are a possible obstacle to using porcine organs in addition to the immunological barriers. Three main types of PERVs (A, B and C) have been previously investigated in diverse pig breeds. To examine the copy numbers of PERVs and their genomic locations in the Korean native pig genome, we screened a BAC (Bacterial Artificial Chromosome) library with PERV-specific protease primers for initial recognition of PERV-positive clones and three sets of envelope-specific primers for the identification of PERV types. A total of 45 PERV-positive clones, nine PERV-A and 36 PERV-B, have been identified from the library screening and the BAC contigs were constructed using the primers designed from BAC end sequences (BESs). These primers were also used for SCH (Somatic Cell Hybrid) and RH (Radiation Hybrid) mapping of the PERV-positive clones. The results indicate that 45 PERV-positive BAC clones belong to nine contigs and a singleton. SCH and IMpRH (INRA-Minnesota Porcine Radiation Hybrid) mapping results indicated that there are at least eight separate PERV genomic locations, consisting of three PERV-A and five PERV-B. One contig could not be mapped, and two contigs are closely located on SSC7. Southern blotting indicates there may be up to 15 additional sites. Further investigation of these clones will contribute to a general strategy to generate PERV-free lines of pigs suitable for xenotransplantation.     

An Imported Case of Cystic Echinococcosis in the Liver

A 25-year-old Uzbek male presented with right upper abdominal pain for 20 days. On radiologic studies, a huge cystic mass was noticed in the right liver which was suspected as parasitic. The patient received right hepatic segmentectomy (segment 7), and the surgically resected mass was confirmed as cystic echinococcosis (CE), measuring 10.5 cm in its diameter. The inner surface of the cyst was bile-stained. The patient was discharged on the 8th hospital day, and was rechecked 6 months after the surgical intervention without any evidence of recurrence. The present report describes findings of an imported case of CE which represented ultrasound images of the ''ball of wool''.     

Altered cortical synaptic morphology and impaired memory consolidation in forebrain- specific dominant-negative PAK transgenic mice

Molecular and cellular mechanisms for memory consolidation in the cortex are poorly known. To study the relationships between synaptic structure and function in the cortex and consolidation of long-term memory, we have generated transgenic mice in which catalytic activity of PAK, a critical regulator of actin remodeling, is inhibited in the postnatal forebrain. Cortical neurons in these mice displayed fewer dendritic spines and an increased proportion of larger synapses compared to wild-type controls. These alterations in basal synaptic morphology correlated with enhanced mean synaptic strength and impaired bidirectional synaptic modifiability (enhanced LTP and reduced LTD) in the cortex. By contrast, spine morphology and synaptic plasticity were normal in the hippocampus of these mice. Importantly, these mice exhibited specific deficits in the consolidation phase of hippocampus-dependent memory. Thus, our results provide evidence for critical relationships between synaptic morphology and bidirectional modifiability of synaptic strength in the cortex and consolidation of long-term memory.     

Structural analysis of <Emphasis Type="Italic">N</Emphasis>-/<Emphasis Type="Italic">O</Emphasis>-glycans assembled on proteins in yeasts

Protein glycosylation, the most universal and diverse post-translational modification, can affect protein secretion, stability, and immunogenicity. The structures of glycans attached to proteins are quite diverse among different organisms and even within yeast species. In yeast, protein glycosylation plays key roles in the quality control of secretory proteins, and particularly in maintaining cell wall integrity. Moreover, in pathogenic yeasts, glycans assembled on cell-surface glycoproteins can mediate their interactions with host cells. Thus, a comprehensive understanding of protein glycosylation in various yeast species and defining glycan structure characteristics can provide useful information for their biotechnological and clinical implications. Yeast-specific glycans are a target for glyco-engineering; implementing human-type glycosylation pathways in yeast can aid the production of recombinant glycoproteins with therapeutic potential. The virulenceassociated glycans of pathogenic yeasts could be exploited as novel targets for antifungal agents. Nowadays, several glycomics techniques facilitate the generation of species-and strain-specific glycome profiles and the delineation of modified glycan structures in mutant and engineered yeast cells. Here, we present the protocols employed in our laboratory to investigate the N-and O-glycan chains released from purified glycoproteins or cell wall mannoproteins in several yeast species.