Neoagarobiose (NA2) is the repeating disaccharide unit of agarose and possesses various promising biological activities. To identify an efficient exolytic βagarase required for NA2 production from agarose, the GH50A β-agarase gene from agar-degrading Cellvibrio sp. KY-GH-1 was overexpressed as a recombinant Histagged protein using the Escherichia coli expression system. GH50A β-agarase that consists of 797 amino acids was able to produce predominantly NA2 from agarose at an optimal temperature and pH of 35 °C and 7.5, respectively. The enzyme was stable up to 35 °C and within a pH range of 7.0−9.0. The K m , V max , K cat , and K cat /K m values of the enzyme were 26.5 mg/mL, 16.9 U/mg, 25.2 s −1 , and 1.2 × 10 5 s −1 M −1 , respectively. The copresence of 5 mM MnSO 4 and 10 mM tris(2-carboxyethyl)phosphine (TCEP) resulted in a 2.5-fold enhancement of the enzyme activity. For NA2 production, neoagaro-oligosaccharides (NAOSs) containing NA4−NA18 were preferred over agarose or agaro-oligosaccharides (AOSs) as substrates. NA2 was produced along with minor amounts of agarotriose (A3) after treatment of AOS with the enzyme, indicating that the exolytic digestion of AOS by the enzyme was initiated by releasing A3 from nonreducing ends. Enzymatic hydrolysis of 0.4% agarose (100 mL) using GH50A β-agarase (20 μg/mL) for 4 h under optimal reaction conditions (5 mM MnSO 4 , 10 mM TCEP, 35 °C, 20 mM Tris−HCl, and pH 7.5) and purification of NA2 from hydrolysis products by Bio-Gel P-2 column chromatography resulted in the recovery of 216 mg of NA2 (∼54% yield from agarose). Altogether, these results suggest that the recombinant GH50A β-agarase is useful to convert agarose to NA2.

Hydrogen sulfide is well-known to exhibit anti-inflammatory and cytoprotective activities, and also has protective effects in the liver. This study aimed to examine the protective effect of hydrogen sulfide in rats with hepatic encephalopathy, which was induced by mild bile duct ligation. In this rat model, bile ducts were mildly ligated for 26 days. Rats were treated for the final 5 days with sodium hydrosulfide (NaHS). NaHS (25 µmol/kg), 0.5% sodium carboxymethyl cellulose, or silymarin (100 mg/kg) was administered intraperitoneally once per day for 5 consecutive days. Mild bile duct ligation caused hepatotoxicity and inflammation in rats. Intraperitoneal NaHS administration reduced levels of aspartate aminotransferase and alanine aminotransferase, which are indicators of liver disease, compared to levels in the control mild bile duct ligation group. Levels of ammonia, a major causative factor of hepatic encephalopathy, were also significantly decreased. Malondialdehyde, myeloperoxidase, catalase, and tumor necrosis factor-α levels were measured to confirm antioxidative and anti-inflammatory effects. N-Methyl-D-aspartic acid (NMDA) receptors with neurotoxic activity were assessed for subunit NMDA receptor subtype 2B. Based on these data, NaHS is suggested to exhibit hepatoprotective effects and guard against neurotoxicity through antioxidant and anti-inflammatory actions.

Most diabetic patients experience diabetic mellitus (DM) urinary bladder dysfunction. A number of studies evaluate bladder smooth muscle contraction in DM. In this study, we evaluated the change of bladder smooth muscle contraction between normal rats and DM rats. Furthermore, we used pharmacological inhibitors to determine the differences in the signaling pathways between normal and DM rats. Rats in the DM group received an intraperitoneal injection of 65 mg/kg streptozotocin and measured blood glucose level after 14 days to confirm DM. Bladder smooth muscle contraction was induced using acetylcholine (ACh, 10−4 M). The materials such as, atropine (a muscarinic receptor antagonist), U73122 (a phospholipase C inhibitor), DPCPX (an adenosine A1 receptor antagonist), udenafil (a PDE5 inhibitor), prazosin (an α1-receptor antagonist), papaverine (a smooth muscle relaxant), verapamil (a calcium channel blocker), and chelerythrine (a protein kinase C inhibitor) were pre-treated in bladder smooth muscle. We found that the DM rats had lower bladder smooth muscle contractility than normal rats. When prazosin, udenafil, verapamil, and U73122 were pre-treated, there were significant differences between normal and DM rats. Taken together, it was concluded that the change of intracellular Ca2+ release mediated by PLC/IP3 and PDE5 activity were responsible for decreased bladder smooth muscle contractility in DM rats.

A Dieulafoy lesion is a relatively rare, but potentially life threatening cause of gastrointestinal bleeding, which accounts for only 1~2% of acute cases. The most common site is the stomach and most extragastric lesions are frequently found in the duodenum followed by the esophagus, the colon, and rectum. However, jejunum and ileum are extremely rare. I report on a case of a 38-year-old female who underwent laparoscopic resection of a bleeding Dieulafoy's lesion in the jejunum following intraoperative endoscopy.

Author contributions: U.D.S. organized and supervised all procedures. G.M.K. and H.J.S. performed data analysis and revised the work protocol and manuscript. G.M.K., H.J.S., and W.S.C. participated in research design and contributed the analytical techniques and tools. G.M.K. conducted experiments, including design, and contributed to the writing of the manuscript.