Spatial distribution of mumps in South Korea, 2001-2015: identifying clusters and population risk factors.

In South Korea, the resurgence of mumps was noted primarily among school-aged children and adolescents since 2000. We analyzed spatial patterns in mumps incidence to give an indication to the geographical risk. We used National Notifiable Disease Surveillance System data from 2001 to 2015, classifying into three periods according to the level of endemicity. A geographic-weighted regression analysis was performed to find demographic predictors of mumps incidence according to district level. We assessed the association between the total population size, population density, percentage of children (age 0-19 years), timely vaccination rate of measles-mumps-rubella vaccines and the higher incidence rate of mumps. During low endemic periods, there were sporadic regional distributions of outbreak in the central and northern part of the country. During intermediate endemic periods, the increase of incidence was noted across the country. During high endemic period, a nationwide high incidence of mumps was noted especially concentrated in southwestern regions. A clear pattern for the mumps cluster shown through global spatial autocorrelation analysis from 2004 to 2015. The 'non-timely vaccination coverage' (P = 0·002), and 'proportion of children population' (P < 0·001) were the predictors for high mumps incidence in district levels. Our study indicates that the rate of mumps incidence according to geographic regions vary by population proportion and neighboring regions, and timeliness of vaccination, suggesting the importance of community-level surveillance and improving of timely vaccination.

Outbreak of enterotoxigenic Escherichia coli O169 enteritis in schoolchildren associated with consumption of kimchi, Republic of Korea, 2012.

Enterotoxigenic Escherichia coli (ETEC) is now recognized as a common cause of foodborne outbreaks. This study aimed to describe the first ETEC O169 outbreak identified in Korea. In this outbreak, we identified 1642 cases from seven schools. Retrospective cohort studies were performed in two schools; and case-control studies were conducted in five schools. In two schools, radish kimchi was associated with illness; and in five other schools, radish or cabbage kimchi was found to have a higher risk among food items. Adjusted relative risk of kimchi was 5·87-7·21 in schools that underwent cohort studies; and adjusted odds ratio was 4·52-12·37 in schools that underwent case-control studies. ETEC O169 was isolated from 230 affected students, and was indistinguishable from the isolates detected from the kimchi product distributed by company X, a food company that produced and distributed kimchi to all seven schools. In this outbreak, we found that the risk of a kimchi-borne outbreak of ETEC O169 infection is present in Korea. We recommend continued monitoring regarding food safety in Korea, and strengthening surveillance regarding ETEC O169 infection through implementation of active laboratory surveillance to confirm its infection.

Patterns of bcl-2 expression in placenta.

A total of 39 placentas, whose gestational ages ranged from 8 to 41 weeks, were analyzed for bcl-2 expression using immunohistochemistry and immunoblotting. Immunohistochemically, both intracytoplasmic and nuclear expression of bcl-2 was observed in villous and extravillous trophoblasts, villous mesenchymal cells and capillary endothelial cells, villous macrophages, intermediate trophoblasts, amnionic epithelium, and even in decidua and endometrial glandular epithelium in early gestational periods. The degree of expression significantly decreased in the placentas after the gestational period of 32 weeks which coincides with the declining phase of placental increase. On immunoblotting lysates of 10(4) cells from single cell suspensions of fresh placentas, bcl-2 was detected in the placentas of 22 and 33 gestational weeks, but it was negligible or absent in three term placentas. The results of the present study suggest two possible implications on the role of bcl-2 in placenta: 1) it may be a type of proliferation or maturation-related marker, especially of trophoblasts, which show decreased expression along with terminal differentiation and maturation, and 2) because the primary role of bcl-2 is the inhibition of programmed cell death (PCD), the decrease in placental bcl-2 around term may be a parturition-associated biological change.

Bcl-2 expression in neuroblastoma is differentially regulated by differentiation inducers.

Neuroblastoma is characterized by differentiation in vivo and in vitro, and the process is known to be associated with changes in various gene expressions, among which is the bcl-2 gene whose major function may be potentially involved in the resistance to anticancer chemotherapy. We investigated the changing patterns of bcl-2 expression in neuroblastoma cell lines according to differentiation to assess whether the expression patterns can be differentially modulated by different types of differentiation inducers. Differentiation was induced in two neuroblastoma cell lines [SK-N-SH, SK-N-BE(2)] using all-trans-retinoic acid, gamma-interferon and EHS laminin, respectively. The levels of expression of bcl-2 were analysed before and after differentiation using immunoblotting and subsequent densitometry. The expression patterns of bcl-2 differed according to the type of differentiation inducers. Its expression increased when treated with retinoic acid and EHS laminin along with neuronal differentiation, while differentiation with gamma-interferon treatment was associated with decreased bcl-2 expression. Decreased expression of bcl-2 despite neuronal differentiation induced by gamma-interferon was thought to be important in that a certain differentiation pathway without increased drug resistance-related factor expression exists, which in turn has implications for the clinical application of gamma-interferon, combined with chemotherapy.