Abortive meiosis in the oogenesis of parthenogenetic <Emphasis Type="Italic">Daphnia pulex</Emphasis>

Most daphnid species adopt parthenogenesis and sexual reproduction differentially in response to varied environmental cues, resulting in the production of diploid progenies in both cases. Previous studies have reportedly suggested that daphnids produce their parthenogenetic eggs via apomixis; the nuclear division of mature oocytes should be an equational division similar to somatic mitosis. However, it seems premature to conclude that this has been unequivocally established in any daphnids. Therefore, the objective of our research was to precisely reveal the process and mechanism of parthenogenetic oogenesis and maintenance of diploidy in Daphnia pulex through histology, karyology, and immunohistochemistry. We found that, when a parthenogenetic egg entered the first meiosis, division was arrested in the early first anaphase. Then, two half-bivalents, which were dismembered from each bivalent, moved back to the equatorial plate and assembled to form a diploid equatorial plate. Finally, the sister chromatids were separated and moved to opposite poles in the same manner as the second meiotic division followed by the extrusion of one extremely small daughter cell (resembling a polar body). These results suggest that parthenogenetic D. pulex do not adopt typical apomixis. We hypothesize that D. pulex switches reproductive mode depending on whether the egg is fertilized or not.     

Detection and molecular characterization of porcine toroviruses in Korea

This study examined the prevalence and genetic diversity of the porcine torovirus (PToV) in Korea. Of 295 samples, 19 (6.4%) samples tested positive for PToVs by RT-PCR. A low nucleotide sequence identity of the partial S gene was detected among the Korean PToVs (73.5%) and between the Korean and European PToVs (74.0%). Phylogenetic analysis of the spike and nucleocapsid genes showed that the Korean PToVs form distinct branches with clusters corresponding to the farm of origin, which were separate from the other known foreign PToVs. These findings suggest that genetically diverse Korean PToV strains cause sporadic infections in Korea.     

Human papillomavirus type 16 E6 and E7 oncoproteins act synergistically to cause head and neck cancer in mice

High-risk human papillomaviruses (HPVs) contribute to cervical and other anogenital cancers, and they are also linked etiologically to a subset of head and neck squamous cell carcinomas (HNSCC). We previously established a model for HPV-associated HNSCC in which we treated transgenic mice expressing the papillomaviral oncoproteins with the chemical carcinogen 4-nitroquinoline-1-oxide (4-NQO). We found that the HPV-16 E7 oncoprotein was highly potent in causing HNSCC, and its dominance masked any potential oncogenic contribution of E6, a second papillomaviral oncoprotein commonly expressed in human cancers. In the current study, we shortened the duration of treatment with 4-NQO to reduce the incidence of cancers and discovered a striking synergy between E6 and E7 in causing HNSCC. Comparing the oncogenic properties of wild-type versus mutant E6 genes in this model for HNSCC uncovered a role for some but not other cellular targets of E6 previously shown to contribute to cervical cancer.     

Minocycline inhibits caspase-dependent and -independent cell death pathways and is neuroprotective against hippocampal damage after treatment with kainic acid in mice

Although minocycline has been generally thought to have neuroprotective properties, the neuroprotective role of minocycline has not been investigated in the animal model of epilepsy. In this study, we investigated whether minocycline is neuroprotective against kainic acid (KA)-induced cell death through the caspase-dependent or -independent mitochondrial apoptotic pathways. Adult male ICR mice were subjected to seizures by intrahippocampal KA injection with vehicle or with minocycline. For cell death analysis, TdT-mediated dUTP-biotin nick end labeling and cresyl-violet staining were performed. Western blot analysis and immunofluorescent staining for cytochrome c and apoptosis-inducing factor (AIF) were performed. Cell death was reduced in minocycline-treated mice. Cytosolic translocation of cytochrome c and subsequent activation of caspase-3 were diminished by minocycline treatment. AIF nuclear translocation and subsequent large-scale DNA fragmentation were also reduced in minocycline-treated mice. Thus, this study suggests that minocycline inhibits both caspase-dependent and -independent apoptotic pathways and may be neuroprotective against hippocampal damage after KA treatment.     

Association study of semaphorin 7a (sema7a) polymorphisms with bone mineral density and fracture risk in postmenopausal Korean women

Bone mineral density (BMD), the major factor determining bone strength, is closely related to osteoporotic fracture risk and is determined largely by multiple genetic factors. Semaphorin 7a (SEMA7A), a recently described member of the semaphorin family, has been shown to play a critical role in the activation of monocyte/macrophages that share progenitors with bone-resorbing osteoclasts and thus might contribute to osteoclast development. In the present study, we directly sequenced the SEMA7A gene in 24 Korean individuals, and identified 15 sequence variants. Five polymorphisms (+15667G>A, +15775C>G, +16285C>T, +19317C>T, +22331A>G) were selected and genotyped in postmenopausal Korean women (n=560) together with measurement of the areal BMD (g/cm²) of the anterior-posterior lumbar spine and the non-dominant proximal femur using dual-energy X-ray absorptiometry. We found that polymorphisms of the SEMA7A gene were associated with the BMD of the lumbar spine and femoral neck. SEMA7A+15775C>G and SEMA7A+22331A>G were associated with low BMD of the femoral neck (P=0.02) and lumbar spine (P=0.04) in a recessive model. SEMA7A-ht4 also showed an association with risk of vertebral fracture (OR=1.87–1.93, P=0.02–0.03). Our results suggest that variations in SEMA7A may play a role in decreased BMD and risk of vertebral fracture.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized usersJung-Min Koh and Bermseok Oh contributed equally to this work     

Iatrogenic Kaposi's sarcoma following steroid therapy for nonspecific interstitial pneumonia with HHV-8 genotyping

We present a case of iatrogenic Kaposi's sarcoma (KS) in a 64-year-old, human immunodeficiency virus (HIV)-negative woman with nonspecific interstitial pneumonia (NSIP) following steroid therapy. She suffered from longstanding exertional dyspnea, and was diagnosed to have NSIP by a thoracoscopic lung biopsy. After 4 months of steroid therapy, multiple purplish nodular or patchy skin lesions developed throughout the entire body. Microscopically, the skin lesions, consisting of closely packed spindle cells forming slit-like vascular structures, were diagnosed as typical KSs. The tumor cells were positive for CD34, factor VIII-related antigen, and human herpesvirus 8 (HHV-8) immunostainings. Using fresh tumor tissue and peripheral blood, polymerase chain reactions revealed the presence of HHV-8. Phylogenetic analysis of HHV-8 ORF K1 genes disclosed that the strain belonged to the subtype II/C and had the M allele at the right-hand side of the genome. To the best of our knowledge, this case report is the first documentation of iatrogenic KS associated with NSIP. A brief review focusing on the HHV-8 genotypes of iatrogenic KS is also presented.     

Comparison of efficacy of cefoperazone/sulbactam and imipenem/cilastatin for treatment of Acinetobacter bacteremia

Multiple antibiotic resistance threatens successful treatment of Acinetobacter baumannii infections worldwide. Increasing interest in the well-known activity of sulbactam against the genus Acinetobacter has been aroused. The purpose of this study was to compare the outcomes for patients with Acinetobacter bacteremia treated with cefoperazone/sulbactam versus imipenem/cilastatin. Forty-seven patients with Acinetobacter baumannii bacteremia were analyzed through a retrospective review of their medical records for antibiotic therapy and clinical outcome. Thirty-five patients were treated with cefoperazone/sulbactam, and twelve patients with imipenem/cilastatin. The percentage of favorable response after 72 hours was not statistically different between cefoperazone/sulbactam group and imipenem/cilastatin group. The mortality rate was not statistically different, too. Cefoperazone/sulbactam was found to be as useful as imipenem/cilastatin for treating patients with Acinetobacter bacteremia.     

Massively parallel signature sequencing profiling of fetal human neural precursor cells

We have examined gene expression in multipotent neural precursor cells (NPCs) derived from human fetal (f) brain tissue and compared its expression profiles with embryonic stem (ESC) cells, embryoid body cell (EBC), and astrocyte precursors using the technique of massively parallel signature sequencing (MPSS). Gene expression profiles show that fNPCs express core neural stem cells markers and share expression profiles with astrocyte precursor cells (APCs) rather than ESC or EBC. Gene expression analysis shows that fNPCs differ from other adult stem and progenitor cells in their marker expression and activation of specific functional networks such as the transforming growth factorbeta (TGFbeta) and Notch signaling pathways. In addition, our results allow us to identify novel genes expressed in fNPCs and provide a detailed profile of fNPCs.     

Adaptive responses induced by low dose radiation in dentate gyrus of rats

The purpose of this study is to investigate the mechanism of alternative responses to low dose irradiation for neuronal cell proliferation in the dentate gyrus of rats. To determine the effect of a single exposure to radiation, rats were irradiated with a single dose of 0.1, 1, 10 or 20 Gy. To determine the effect of the cumulative dose, the animals were irradiated daily with 0.01 Gy or 0.1 Gy from 1 to 4 days. The neuronal cell proliferation was evaluated using immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU), Ki-67 and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. Four consecutive daily irradiations with a 0.01 Gy/fraction increased the number of BrdU-positive and Ki-67-positive cells in a dose dependent manner, but this did not affect the number of TUNEL-positive cells. However, there was not a dose dependent relationship for the 0.1 Gy/fraction irradiation with the number of BrdU, Ki-67 and TUNEL positive cells. Our data support the explanation that the adaptive response, induced by low-dose radiation, in the hippocampus of rats is more likely a reflection of the perturbations of cell cycle progression.     

Artemisia iwayomogi inhibits immediate-type allergic reaction and inflammatory cytokine secretion

The immediate-type allergic reaction is involved in many allergic diseases such as asthma and allergic rhinitis. The discovery of drugs for the treatment of immediate-type allergic diseases is a very important subject in human health. In this study, we investigated the effect of Artemisia iwayomogi (AIAE) on mast cell-mediated allergic reaction and inflammatory cytokine secretion. AIAE inhibited compound 48/80-induced systemic reactions in mice. AIAE decreased the passive cutaneous anaphylaxis (PCA) reaction activated by antidinitrophenyl (anti-DNP) IgE antibody. AIAE dose-dependently reduced histamine release from rat peritoneal mast cells activated by compound 48/80 or anti-DNP IgE. Furthermore, AIAE attenuated the phorbol 12-myristate 13-acetate plus calcium ionophore A23187-stimulated tumor necrosis factor-alpha and interleukin-6 secretion in human mast cells. These results provide evidence that AIAE may be beneficial in the treatment of allergic diseases.