Involvement of peroxiredoxin 2 in cumulus expansion and oocyte maturation in mice.

Peroxiredoxin 2 (Prdx2), an antioxidant enzyme, is expressed in the ovary during the ovulatory process. The aim of the present study was to examine the physiological role of Prdx2 during ovulation using Prdx2-knockout mice and mouse cumulus-oocyte complex (COC) from WT mice. Two days of treatment of immature mice (21-23 days old) with equine chorionic gonadotrophin and followed by treatment with human chorionic gonadotrophin greatly impaired cumulus expansion and oocyte maturation in Prdx2-knockout but not wild-type mice. Treatment of COCs in culture with conoidin A (50µM), a 2-cys Prdx inhibitor, abolished epiregulin (EPI)-induced cumulus expansion. Conoidin A treatment also inhibited EPI-stimulated signal molecules, including signal transducer and activator of transcription-3, AKT and mitogen-activated protein kinase 1/2. Conoidin A treatment also reduced the gene expression of EPI-stimulated expansion-inducing factors (hyaluronan synthase 2 (Has2), pentraxin 3 (Ptx3), TNF-α induced protein 6 (Tnfaip6) and prostaglandin-endoperoxide synthase 2 (Ptgs2)) and oocyte-derived factors (growth differentiation factor 9 (Gdf9) and bone morphogenetic protein 15 (Bmp15)). Furthermore, conoidin A inhibited EPI-induced oocyte maturation and the activity of connexins 43 and 37. Together, these results demonstrate that Prdx2 plays a role in regulating cumulus expansion and oocyte maturation during the ovulatory process in mice, probably by modulating epidermal growth factor receptor signalling.

Choroidal Thickness Variation According to Refractive Error Measured by Spectral Domain-optical Coherence Tomography in Korean Children.

PURPOSE: To assess choroidal thickness (CT) variation according to refractive errors using enhanced-depth imaging optical coherence tomography. METHODS: Eighty-nine eyes (in 89 children) <±6 diopter were categorized into three groups: hyperopia, emmetropia, and myopia, according to refractive error, and underwent choroidal scans using enhanced-depth imaging-optical coherence tomography. CT was measured at the fovea and at 1 mm and 3 mm nasal (N1 and N3), temporal (T1 and T3), superior (S1 and S3), and inferior (I1 and I3) from the fovea. RESULTS: Mean foveal CTs were 346.86 µm, 301.97 µm, and 267.46 µm in the hyperopia, emmetropia, and myopia groups, respectively (p < 0.05). CTs at N3 and T3 were 214.59 µm and 318.68 µm, 163.92 µm and 320.79 µm, and 153.93 µm and 295.61 µm in the hyperopia, emmetropia, and myopia groups, respectively (p < 0.05). All CTs in the hyperopia group were thicker than those of other groups (p < 0.05). Fovea was thickest and was significantly thicker than at N3 and I3 in hyperopia (p < 0.05). T3 thickness in the emmetropia and myopia groups was greater than thickness at other areas, particularly the nasal and inferior choroids (p < 0.05). CT was positively correlated with spherical equivalent (p = 0.029). CONCLUSIONS: In Korean children, CTs were greater in the hyperopia group than in the emmetropia and myopia groups. The temporal choroid was thicker than the nasal choroid, regardless of the refractive error. The thickest location in the hyperopia group was the fovea; however, the temporal choroid was thickest in the emmetropia and myopia groups.

Effect of surface morphology on friction of graphene on various substrates.

The friction of graphene on various substrates, such as SiO2, h-BN, bulk-like graphene, and mica, was investigated to characterize the adhesion level between graphene and the underlying surface. The friction of graphene on SiO2 decreased with increasing thickness and converged around the penta-layers due to incomplete contact between the two surfaces. However, the friction of graphene on an atomically flat substrate, such as h-BN or bulk-like graphene, was low and comparable to that of bulk-like graphene. In contrast, the friction of graphene folded onto bulk-like graphene was indistinguishable from that of mono-layer graphene on SiO2 despite the ultra-smoothness of bulk-like graphene. The characterization of the graphene's roughness before and after folding showed that the corrugation of graphene induced by SiO2 morphology was preserved even after it was folded onto an atomically flat substrate. In addition, graphene deposited on mica, when folded, preserved the same corrugation level as before the folding event. Our friction measurements revealed that graphene, once exfoliated from the bulk crystal, tends to maintain its corrugation level even after it is folded onto an atomically flat substrate and that ultra-flatness in both graphene and the substrate is required to achieve the intimate contact necessary for strong adhesion.

Periovulatory expression of hydrogen peroxide-induced sulfiredoxin and peroxiredoxin 2 in the rat ovary: gonadotropin regulation and potential modification.

Reactive oxygen species are involved in ovulation. The aim of this study was to examine gonadotropin regulation of antioxidant enzyme sulfiredoxin (Srx) and peroxiredoxin 2 (PRDX2) expressions and modification during the ovulatory process in rats. Administration of antioxidants in vivo reduced ovulation rate and cumulus expansion. LH treatment increased H(2)O(2) levels within 15 min, which, in turn, induced Srx gene expression in cultured preovulatory follicles. Treatment of preovulatory follicles with catalase suppressed the stimulatory effect of LH on Akt phosphorylation. LH- or H(2)O(2)-stimulated Srx mRNA levels were suppressed by inhibitors of antioxidant agents and MAPK kinase. An in vivo injection of equine chorionic gonadotropin-human chorionic gonadotropin (hCG) stimulated Srx mRNA within 1 h in granulosa but not thecal cells of preovulatory follicles. Srx protein levels were stimulated from 3 h post-hCG injection. Immunofluorescence analysis revealed that oocytes expressed the Srx protein. Furthermore, hCG treatment increased Srx expression in mural granulosa, theca and cumulus cells, but the Srx protein was not detected in corpora lutea. Gene expression of PRDX2, identified as an Srx-dependent modified enzyme, was stimulated by gonadotropins. In situ hybridization analysis demonstrated that PRDX2 mRNA was detected in oocytes and theca cells as well as granulosa cells of some antral and preovulatory follicles. High levels of PRDX2 mRNA were detected in corpora lutea. Total levels of PRDX2 protein were not changed by gonadotropins. However, levels of hyperoxidized PRDX2 increased within 2-3 h after the hCG injection. Taken together, gonadotropin stimulation of Srx expression and PRDX2 modification in the ovary suggest the existence of an antioxidant system to maintain H(2)O(2) production and elimination during the periovulatory period.

The first case of genotype 4 hepatitis E related to wild boar in South Korea.

Several cases of serologically diagnosed hepatitis E have been reported in South Korea; however, there have been no documented cases of zoonotic transmission with virologic characterization of hepatitis E virus (HEV). We report on a sporadic case of autochthonous acute hepatitis E after ingestion of raw bile juice obtained from a wild boar living on a domestic mountain in a southern part of Korea. It is the first case of hepatitis E acquired through presumably zoonotic transmission, which was verified as genotype 4 HEV.

The complete genome sequence and molecular analysis of human hepatitis E virus genotype IV identified from a Korean patient.

Hepatitis E virus (HEV) was originally identified as the etiological agent of non-HAV enterically transmitted hepatitis. One HEV strain (FJ763142) was identified from an acute viral hepatitis E patient with IgM anti-HEV in Korea. The complete genome sequence consisted of 7,238 nucleotides (nt) plus a 22-nt poly(A) tail. The strain belongs to genotype IV, with 91% homology compared with AB197674, which was found in a Japanese patient who had traveled to China. This finding suggests that HEV genotype IV already circulates in Korea, and this HEV might be the first example of an indigenous strain.

Gastroesophageal flap valve is associated with gastroesophageal and gastropharyngeal reflux.

BACKGROUND: The endoscopic grade of the gastroesophageal flap valve (GEFV) is suggested to be a good predictor of reflux status. The aim of this study was to investigate the association of the GEFV and gastroesophageal and gastropharyngeal reflux. METHODS: A total of 364 patients (151 men and 233 women; mean age, 52.2 years) who underwent endoscopy, esophageal manometry, and ambulatory 24-h dual-probe pH monitoring were included. GEFV was graded I through IV using Hill's classification; then, GEFV was classified into two groups: a normal GEFV group (grades I and II) and an abnormal GEFV group (grades III and IV). Findings of endoscopy, esophageal manometry, and ambulatory pH monitoring were compared between the groups. RESULTS: Increased GEFV grade was significantly associated with an increased prevalence of both reflux esophagitis and Barrett's epithelium (P < 0.001). Lower esophageal sphincter pressure was significantly lower in the abnormal GEFV group than in the normal GEFV group (P < 0.001). All variables showing gastroesophageal reflux in the distal probe were significantly higher in the abnormal GEFV group than in the normal GEFV group (P < 0.001). In addition, all variables, except the supine time of pH < 4, showing gastropharyngeal reflux in the proximal probe were significantly higher in the abnormal GEFV group than in the normal GEFV group (P < 0.001). The frequency of gastroesophageal reflux disease and of gastropharyngeal reflux disease was significantly higher in the abnormal GEFV group than in the normal GEFV group (P < 0.001). CONCLUSION: Endoscopic grading of the GEFV is easy and provides useful information about the status of gastroesophageal and gastropharyngeal reflux.