The involvement of Eph–Ephrin signaling in tissue separation and convergence during Xenopus gastrulation movements

AbstractIn Xenopus gastrulation, the involuting mesodermal and non-involuting ectodermal cells remain separated from each other, undergoing convergent extension. Here, we show that Eph–ephrin signaling is crucial for the tissue separation and convergence during gastrulation. The loss of EphA4 function results in aberrant gastrulation movements, which are due to selective inhibition of tissue constriction and separation. At the cellular levels, knockdown of EphA4 impairs polarization and migratory activity of gastrulating cells but not specification of their fates. Importantly, rescue experiments demonstrate that EphA4 controls tissue separation via RhoA GTPase in parallel to Fz7 and PAPC signaling. In addition, we show that EphA4 and its putative ligand, ephrin-A1 are expressed in a complementary manner in the involuting mesodermal and non-involuting ectodermal layers of early gastrulae, respectively. Depletion of ephrin-A1 also abrogates tissue separation behaviors. Therefore, these results suggest that Eph receptor and its ephrin ligand might mediate repulsive interaction for tissue separation and convergence during early Xenopus gastrulation movements

A Case of Endoscopic Resection of a Colonic Semipedunculated Leiomyoma

During colonoscopic examination, epithelial lesions, such as adenomatous polyps, are frequently encountered, unlike subepithelial lesions, such as leiomyomas, which are uncommon. A colonic leiomyoma is a rare tumor, originating either from the mucularis mucosa or from the proper muscle, and accounts for only 3% of all gastrointestinal leiomyomas. Colonic leiomyomas are usually benign and asymptomatic. However, they can sometimes cause symptoms, ie, abdominal pain, intestinal obstruction, hemorrhage, and perforation. The traditional management option for a colonic leiomyoma is surgical resection. Recently, with the development of endoscopy devices and techniques, the endoscopic resection has been considered as an alternative treatment option. We experienced a patient with a leiomyoma that was diagnosed during colonoscopy. The leiomyoma was resected endoscopically without complication. We report this case with a review of the literature

Potential Usefulness of Streptococcus pneumoniae

The secretion of extracellular membrane vesicles (EMVs) is a common phenomenon that occurs in archaea, bacteria, and mammalian cells. The EMVs of bacteria play important roles in their virulence, biogenesis mechanisms, and host cell interactions. Bacterial EMVs have recently become the focus of attention because of their potential as highly effective vaccines that cause few side effects. Here, we isolated the EMVs of Streptococcus pneumoniae and examined their potential as new vaccine candidates. Although the S. pneumoniae bacteria were highly pathogenic in a mouse model, the EMVs purified from these bacteria showed low pathological activity both in cell culture and in mice. When mice were injected intraperitoneally with S. pneumoniae EMVs and then challenged, they were protected from both the homologous strain and another pathogenic serotype of S. pneumoniae. We also identified a number of proteins that may have immunogenic activity and may be responsible for the immune responses by the hosts. These results suggest that S. pneumoniae EMVs or their individual immunogenic antigens may be useful as new vaccine agents

Effects of remote ischemic postconditioning on hepatic injury in lipopolysaccharide-induced endotoxemic rats

Background Remote ischemic postconditioning (RIPoC) is induced by several cycles of brief, reversible, mechanical blood flow occlusion, and reperfusion of the distal organs thereby protecting target organs. We investigated if RIPoC ameliorated liver injury in a lipopolysaccharide (LPS)-induced endotoxemic rats. Methods Protocol 1) Rats were administered LPS and samples collected at 0, 2, 6, 12, and 18 h. 2) After RIPoC at 2, 6, and 12 h (L+2R+18H, L+6R+18H, and L+12R+18H), samples were analyzed at 18 h. 3) RIPoC was performed at 2 h, analysis samples at 6, 12, 18 h (L+2R+6H, L+2R+12H, L+2R+18H), and RIPoC at 6 h, analysis at 12 h (L+6R+12H). 4) Rats were assigned to a control group while in the RIPoC group, RIPoC was performed at 2, 6, 10, and 14 h, with samples analyzed at 18 h. Results Protocol 1) Liver enzyme, malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), and nuclear factor-κB (NF-κB) levels increased while superoxide dismutase (SOD) levels decreased over time. 2) Liver enzyme and MDA levels were lower while SOD levels were higher in L+12R+18H and L+6R+18H groups when compared with L+2R+18H group. 3) Liver enzyme and MDA levels were lower while SOD levels were higher in L+2R+6H and L+6R+12H groups when compared with L+2R+12H and L+2R+18H groups. 4) Liver enzyme, MDA, TNF-α, and NF-κB levels were lower while SOD levels were higher in RIPoC group when compared with control group. Conclusions RIPoC attenuated liver injury in the LPS-induced sepsis model by modifying inflammatory and oxidative stress response for a limited period

Vasorelaxing Activity of Ulmus davidiana Ethanol Extracts in Rats: Activation of Endothelial Nitric Oxide Synthase

Ulmus davidiana var. japonica Rehder (Urticales: Ulmaceae) (UD) is a tree widespread in northeast Asia. It is traditionally used for anticancer and anti-inflammatory therapy. The present study investigated the effect of an ethanol extract of UD on vascular tension and its underlying mechanism in rats. The dried root bark of UD was ground and extracted with 80% ethanol. The prepared UD extract was used in further analysis. The effect of UD on the cell viability, vasoreactivity and hemodynamics were investigated using propidium iodide staining in cultured cells, isometric tension recording and blood pressure analysis, respectively. Low dose of UD (10~100µg/ml) did not affect endothelial cell viability, but high dose of UD reduced cell viability. UD induced vasorelaxation in the range of 0.1~10µg/ml with an ED50 value of 2µg/ml. UD-induced vasorelaxation was completely abolished by removal of the endothelium or by pre-treatment with L-NAME, an inhibitor of nitric oxide synthase. UD inhibited calcium influx induced by phenylephrine and high K+ and also completely abolished the effect of L-NAME. Intravenous injection of UD extracts (10~100 mg/kg) decreased arterial and ventricular pressure in a dose-dependent manner. Moreover, UD extracts reduced the ventricular contractility (+dP/dt) in anesthetized rats. However, UD-induced hypotensive actions were minimized in L-NAME-treated rats. Taken together, out results showed that UD induced vasorelaxation and has antihypertensive properties, which may be due the activation of nitric oxide synthase in endothelium

Detection of betanodaviruses in apparently healthy aquarium fishes and invertebrates

Betanodaviruses are the causative agents of viral nervous necrosis (VNN) in cultured marine fish. A total of 237 apparently healthy aquarium fish, marine (65 species) and freshwater (12 species) fishes and marine invertebrates (4 species), which were stocked in a commercial aquarium in Seoul, South Korea, were collected from November 2005 to February 2006. The brains of the fish and other tissues of the invertebrates were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and nested PCR to detect betanodavirus. Positive nested PCR results were obtained from the brains of 8 marine fish species (shrimp fish Aeoliscus strigatus, milkfish Chanos chanos, three spot damsel Dascyllus trimaculatus, Japanese anchovy Engraulis japonicus, pinecone fish Monocentris japonica, blue ribbon eel Rhinomuraena quaesita, look down fish Selene vomer, yellow tang Zebrasoma flavesenes), 1 marine invertebrate species (spiny lobster Pamulirus versicolor), and 2 freshwater fish species (South American leaf fish Monocirrhus polyacanthus and red piranha Pygocentrus nattereri). The detection rate in nested PCR was 11/237 (4.64%). These subclinically infected aquarium fish and invertebrates may constitute an inoculum source of betanodaviruses for cultured fishes in the Korean Peninsula