Occurrence and characterization of oseltamivir-resistant influenza virus in children between 2007-2008 and 2008-2009 seasons.

PURPOSE: There was a global increase in the prevalence of oseltamivir-resistant influenza viruses during the 2007-2008 influenza season. This study was conducted to investigate the occurrence and characteristics of oseltamivir-resistant influenza viruses during the 2007-2008 and 2008-2009 influenza seasons among patients who were treated with oseltamivir (group A) and those that did not receive oseltamivir (group B). METHODS: A prospective study was conducted on 321 pediatric patients who were hospitalized because of influenza during the 2007-2008 and 2008-2009 influenza seasons. Drug resistance tests were conducted on influenza viruses isolated from 91 patients. RESULTS: There was no significant difference between the clinical characteristics of groups A and B during both seasons. Influenza A/H1N1, isolated from both groups A and B during the 2007-2008 and 2008-2009 periods, was not resistant to zanamivir. However, phenotypic analysis of the virus revealed a high oseltamivir IC50 range and that H275Y substitution of the neuraminidase (NA) gene and partial variation of the hemagglutinin (HA) gene did not affect its antigenicity to the HA vaccine even though group A had a shorter hospitalization duration and fewer lower respiratory tract complications than group B. In addition, there was no significant difference in the clinical manifestations between oseltamivir-susceptible and oseltamivir-resistant strains of influenza A/H1N1. CONCLUSION: Establishment of guidelines to efficiently treat influenza with oseltamivir, a commonly used drug for treating influenza in Korean pediatric patients, and a treatment strategy with a new therapeutic agent is required.

Effects of spermatozoa during in vitro meiosis progression in the porcine germinal vesicle oocytes.

We have investigated the effect of co-culture with porcine spermatozoa on in vitro maturation of porcine germinal vesicle (GV) oocytes before fertilization. Most oocytes were arrested at the first prophase of meiosis when oocytes were cultured in TCM 199 alone, but the proportion of oocytes that reached metaphase II was significantly elevated by co-incubation with spermatozoa in vitro. The oocyte maturation effect was observed with intact and parts of spermatozoa (head and tail) collected from adult swine (regardless of source). However, gonocytes from the newborn porcine testis were not able to enhance in vitro maturation of porcine germinal vesicle oocytes. Interestingly, the oocyte maturation effect by spermatozoa was not decreased with heat treatment, but the maturation effect of oocyte treatment disappeared with exposure to detergent in sperm suspension. Porcine spermatozoa were also observed to stimulate meiosis of oocytes, which was maintained at meiotic arrest using dibutyryl cyclic AMP or forskolin. The study suggests that (i) membrane of porcine spermatozoa contains a substance(s) that can enhance in vitro maturation of oocytes prior to fertilization, (ii) the putative meiosis-enhancing substance(s) of spermatozoa from adult testes retains the oocyte maturation effect during transportation of spermatozoa through epididymis, and (iii) the putative meiosis-enhancing substance(s) is able to overcome the inhibitory effect of dibutyryl cyclic AMP or forskolin by inducing germinal vesicle breakdown of porcine cumulus-oocyte complexes maintained in meiotic arrest.

Comparison of RAPD, AFLP, and EF-1α Sequences for the Phylogenetic Analysis of Fusarium oxysporum and Its formae speciales in Korea.

Although Fursarium oxysporum causes diseases in economically important plant hosts, identification of F. oxysporum formae speciales has been difficult due to confusing phenotypic classification systems. To resolve these complexity, we evaluated genetic relationship of nine formae speciales of F. oxysporum with random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), and translation elongation factor-1 alpha (EF-1α) gene. In addition, the correlation between mycotoxin content of fusaric acid and isolates based on molecular marker data was evaluated using the modified Mantel's test. According to these result, these fusaric acid-producing strains could not identify clearly, and independent of geographic locations and host specificities. However, in the identification of F. oxysporum formae speciales, especially, AFLP analysis showed a higher discriminatory power than that of a the RAPD and EF-1α analyses, all three techniques were able to detect genetic variability among F. oxysporum formae speciales in this study.

Induction of apoptotic cell death by mycelium extracts of Phellinus linteus in human neuroblastoma cells.

Phellinus linteus is a well-known Oriental medicinal fungus that has various biological activities, including immunomodulatory and anti-tumor activities, the mechanisms of which are poorly understood. In the present study, we investigated the effects of mycelium extracts of P. linteus (MEPL) on the growth of human neuroblastoma SK-N-MC cells. Upon treatment with MEPL, a concentration-dependent inhibition of cell proliferation was observed and cells developed many of the hallmark features of apoptosis, including condensation of chromatin and an increase in the sub-G1 population. The anti-proliferative and apoptotic effects of MEPL were associated with a marked induction of the Bax and cyclin-dependent kinase inhibitor p21. Western blotting and in vitro caspase-3 activity assay demonstrated that the processing/activation of caspases accompanies the generation of MEPL-mediating apoptotic cell death. In addition, the proteolytic cleavage of specific target proteins such as poly(ADP-ribose) polymerase and beta-catenin were observed. Taken together, the present results suggest that apoptotic signals evoked by MEPL in human neuroblastoma SK-N-MC cells may converge caspase-3 activation through an up-regulation of Bax rather than a down-regulation of Bcl-2.