Small intestinal injury caused by NSAIDs/aspirin: finding new from old

Small intestinal injury caused by non-steroidal anti-inflammatory drugs (NSAIDs) or aspirin is an epoch making topic in clinical field with the aid of new devices, capsule endoscopy and double balloon enteroscopy to look at small intestine directly. However, the injury has been reported in animals since more than 40 years ago. Proposed mechanisms are impairment of mucosal defense through inhibition of cyclooxygenase (COX) resulting in deficiency of prostaglandins, and mitochondrial disorder. Possible aggressive factors are NSAIDs/aspirin themselves, bile, and enterobacteria. Translocation of enterobacteria through the mucosa impaired integrity may be the first step of the injury. Bacterial lipopolysaccharides stimulate toll-like receptor-4 in macrophages, which increases proinflammatory cytokines through MyD88 signaling pathway. Finally neutrophils are activated and the small intestinal mucosa is injured with the attacks of NSAIDs/aspirin themselves, bile, and proteolytic enzymes and active oxygen species released by neutrophils. Candidates of treatment tools are prostaglandin derivatives, mucoprotective drugs, probiotics, and mitochondrial protective drugs such as metronidazole and cyclosporin A. Further clinical studies are needed to elucidate the effect in humans.

Advances in characterization of neuroprotective peptide, humanin

Humanin (HN), a short amino acid peptide, protects neurons as well as other cells from amyloid β-induced toxicities and other stresses. A number of HN binding proteins have been identified and their involvements in HN-mediated neuroprotection have been suggested in some cases. However, the way HN binds to the target molecules has never been clarified. Here we will review the structures of HN and HN analogs in solution as a function of solvent conditions and attempt to relate their structural characteristics to the functional properties.

Locoregional mitomycin C injection for esophageal stricture after endoscopic submucosal dissection

This prospective study aimed to evaluate the feasibility and safety of locoregional mitomycin C (MMC) injection to treat refractory esophageal strictures after endoscopic submucosal dissection (ESD) for superficial esophageal carcinoma. Patients with dysphagia and strictures that were refractory to repeated endoscopic balloon dilation (EBD) were eligible. After EBD, MMC was injected into the dilated site. Between June 2009 and August 2010, five patients were recruited. The treatment was performed once in two patients and twice in three patients with recurrent dysphagia or restenosis. In all patients, passing a standard endoscope through the site was easy and the dysphagia grade improved (grade 3→1 in 3 patients, grade 4→2 in 2 patients). No serious complications were noted. During the observation period of 4.8 months, neither recurrent dysphagia nor re-stricture appeared in any of the patients. The combination of locoregional MMC injections and EBD is feasible and safe for the treatment of esophageal strictures after ESD.Recently, endoscopic submucosal dissection (ESD) has been developed and accepted as a new endoscopic treatment for gastrointestinal tumors. ESD is a promising treatment for superficial esophageal carcinoma (SEC), and it has a reliable en bloc resection rate. However, the application of ESD for widespread lesions is challenging because of the high risk of the development of severe strictures, which lead to a low quality of life after ESD. Although endoscopic balloon dilation (EBD) is effective for benign strictures, it needs to be performed frequently until the dysphagia disappears 1. Mitomycin C (MMC), which is a chemotherapeutic agent derived from some Streptomyces species 2, reduces scar formation when topically applied to a surgical lesion. MMC has been applied to treat strictures in a variety of anatomical locations, including a variety of organs 3. The aim of this study was to prospectively evaluate both the feasibility and the safety of locoregional MMC injection therapy in patients with refractory esophageal strictures after ESD for SEC.

Effects of salt and ligand concentrations on the thermal unfolding and refolding of halophilic starch-binding domain from Kocuria varians α-amylase

The starch binding domain of α-amlylase from moderate halophile was expressed in E. coli with His tag (His- SBD12) and characterized for its halophilic properties. His-SBD12 was stable up to 35°C and showed binding activity, although at reduced level, to amylose even in the absence of NaCl. Both NaCl and specific ligands exhibited insignificant influence on the secondary structure of His-SBD12, but showed significant stabilization effects against thermal unfolding concentration-dependently, showing its halophilic properties. NaCl increased thermal stability of His-SBD12 by 4°C at 0.2 M and 15°C at 2 M, and enhanced refolding rate by ~7-fold at 0.2 M and ~170-fold at 2 M. Its specific ligands, β- cyclodextrin (at 3 mM) and maltose (at 470 mM), also stabilized the protein by 11° C, most likely reflecting affinity difference between these two ligands. However, they showed marginal effects on refolding rate. These observations suggest that although binding of NaCl and specific ligands to the native structure can explain their stabilization effects on His- SBD12, it is not a sole factor for modulating their effects on folding of His-SBD12.

Mechanistic insights into protein precipitation by alcohol

Ethanol is used to precipitate proteins during various processes, including purification and crystallization. To elucidate the mechanism of protein precipitation by alcohol, we have investigated the solubility and structural changes of protein over a wide range of alcohol concentrations. Conformation of hen egg-white lysozyme was changed from native to α-helical rich structure in the presence of ethanol at concentrations above 60%. The solubility of lysozyme was reduced with increasing ethanol concentration, although gel formation at ethanol concentrations between 60% and 75% prevented accurate solubility measurements. SH-modified lysozyme showed largely unfolded structure in water and α-helical structure in the presence of ethanol. More importantly, solubility of the chemically modified lysozyme molecules decreased with increasing ethanol concentration. There is no indication of increased solubility upon unfolding of the lysozyme molecules by ethanol, indicating that any favorable interaction of ethanol with the hydrophobic side chains, if indeed occuring, is offset by the unfavorable interaction of ethanol with the hydrophilic side chains and peptide bonds.

Drug solubilization effect of lauroyl-L-glutamate

This article proposes a new technique for the solubilization of poorly soluble drugs using lauroyl-L-glutamate, which is one of the amino acid detergents, with additional small additives. Lauroyl-L-glutamate was highly effective in solubilizing long-chain alkyl gallates, e.g. dodecyl gallate. Furthermore, lauroyl-L-glutamate and small additives, particularly arginine, acted to increase the solubility of alkyl gallates. The synergistic effect was not observed by sodium dodecyl sulphate with arginine. The solubilizing system can be applied to other drugs because of the low toxicity of both lauroyl-L-glutamate and arginine.

Interaction of hexa-His tag with acidic amino acids results in facilitated refolding of halophilic nucleoside diphosphate kinase

We have previously reported that amino-terminal extension sequence containing hexa-His facilitated refolding and assembly of hexameric nucleoside diphosphate kinase from extremely halophilic archaeon Halobacterium salinarum (NDK). In this study, we made various mutations in both the tag sequence and within NDK molecule. SerNDK, in which hexa-His was replaced with hexa-Ser, showed no facilitated folding. In addition, HisD58GD63G, in which both Asp58 and Asp63 in NDK were replaced with Gly, also showed no refolding enhancement. These results suggest that hexa-His in His-tag interact cooperatively with either Asp58 or Asp63 or both. Furthermore, G114D mutant, which formed a dimer in low salt solution, was strongly stabilized by His-tag to form a stable hexamer.

The biological activity of Humanin analogs correlates with structure stabilities in solution

A single mutation has resulted in large differences in neuroprotective activity of a 24 amino acid Humanin (HN). A mutation of Ser7Ala (S7A-HN) resulted in loss of activity, while a mutation of Ser14Gly (S14G-HN) resulted in about 1000-fold increase. The mechanism of the effects conferred by these mutations have been totally unclear, although our recent structure analysis suggested a possibility of the effect of mutation on the structure stability. Here, we have studied the effects of buffer and temperature on the structure of these three HN peptides. These peptides showed a similar disordered structure at 10°C in 10mM phosphate, pH 6.0. They were also similar in phosphate-buffered saline (PBS) as long as the temperature was kept low at 10°C. However, a large difference was observed in both phosphate buffer and PBS between the peptides, when the temperature was raised to a physiological temperature of 37°C. While S14G-HN showed small changes in both solutions at 37°C, the less active HN and inactive S7A-HN showed much larger changes under the identical conditions. In addition, it appeared that structure change at 37°C was faster for S7A-HN than HN. These results show that the structure stability at 37°C increases in the order of S7A-HN, HN and S14G-HN, in correlation with their neuroprotective activities.

Modulation of small molecule solubility and protein binding by arginine

We previously showed that arginine increases the aqueous solubility of the low molecular weight aromatic compounds octyl-gallate (OG) and coumarin. In this study, we focused on acycloguanosine (ACV), an antiherpic agent with moderate aqueous solubility, and examined the effects of arginine on its solubility at a neutral pH. The solubility of ACV increased by approximately 1.9- and 2.6-fold in the presence of 1 and 2 M arginine, respectively, while no solubility changes were observed at an arginine concentration below 0.1 M. These results were found to be consistent with observed changes in OG solubility in the presence of arginine. However, ACV and OG exhibited differential binding to bovine serum albumin (BSA): ACV showed no binding to BSA, while OG showed substantial BSA binding. In conclusion, Arginine partially blocked the protein binding of OG.

Structure, signaling mechanism and regulation of the natriuretic peptide receptor guanylate cyclase

Atrial natriuretic peptide (ANP) and the homologous B-type natriuretic peptide are cardiac hormones that dilate blood vessels and stimulate natriuresis and diuresis, thereby lowering blood pressure and blood volume. ANP and B-type natriuretic peptide counterbalance the actions of the renin-angiotensin-aldosterone and neurohormonal systems, and play a central role in cardiovascular regulation. These activities are mediated by natriuretic peptide receptor-A (NPRA), a single transmembrane segment, guanylyl cyclase (GC)-linked receptor that occurs as a homodimer. Here, we present an overview of the structure, possible chloride-mediated regulation and signaling mechanism of NPRA and other receptor GCs. Earlier, we determined the crystal structures of the NPRA extracellular domain with and without bound ANP. Their structural comparison has revealed a novel ANP-induced rotation mechanism occurring in the juxtamembrane region that apparently triggers transmembrane signal transduction. More recently, the crystal structures of the dimerized catalytic domain of green algae GC Cyg12 and that of cyanobacterium GC Cya2 have been reported. These structures closely resemble that of the adenylyl cyclase catalytic domain, consisting of a C1 and C2 subdomain heterodimer. Adenylyl cyclase is activated by binding of G(s)α to C2 and the ensuing 7° rotation of C1 around an axis parallel to the central cleft, thereby inducing the heterodimer to adopt a catalytically active conformation. We speculate that, in NPRA, the ANP-induced rotation of the juxtamembrane domains, transmitted across the transmembrane helices, may induce a similar rotation in each of the dimerized GC catalytic domains, leading to the stimulation of the GC catalytic activity.

Effects of electrolytes on virus inactivation by acidic solutions

Acidic pH is frequently used to inactivate viruses. We have previously shown that arginine synergizes with low pH in enhancing virus inactivation. Considering a potential application of the acid inactivation of viruses for the prevention and treatment of superficial virus infection at body surfaces and fixtures, herein we have examined the effects of various electrolytes on the acid-induced inactivation of the herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), the influenza A virus (IAV) and the poliovirus upon their incubation at 30˚C for 5 min. Eight electrolytes, i.e., phosphate, NaCl, glutamate, aspartate, pyrrolidone carboxylate, citrate, malate and acetate were tested. No detectable inactivation of the poliovirus was observed under the conditions examined, reflecting its acid-resistance. HSV-1 and HSV-2 responded similarly to the acid-treatment and electrolytes. Some electrolytes showed a stronger virus inactivation than others at a given pH and concentration. The effects of the electrolytes were virus-dependent, as IAV responded differently from HSV-1 and HSV-2 to these electrolytes, indicating that certain combinations of the electrolytes and a low pH can exert a more effective virus inactivation than other combinations and that their effects are virus-specific. These results should be useful in designing acidic solvents for the inactivation of viruses at various surfaces.

Differences between risk factors among irritable bowel syndrome subtypes in Japanese adults

BACKGROUND

Irritable bowel syndrome (IBS) is a common gastrointestinal disease. Detailed clinical characteristics of patients with different IBS subtypes have not been well established. Our aim was to examine the prevalence and risk factors of IBS and its subtypes in Japanese adults.

METHODS

We performed a cross-sectional study of Japanese workers who visited a clinic for a routine health check-up and asked them to fill out a self-report questionnaire. Irritable bowel syndrome and its subtypes were defined by ROME III criteria. A logistic regression model was used to identify risk factors.

KEY RESULTS

Irritable bowel syndrome was present in 367 (13.5%) of 2717 eligible subjects; 79 had IBS with constipation (IBS-C); 102 had IBS with diarrhea (IBS-D); 89 had mixed IBS (IBS-M); and 97 had unsubtyped IBS (IBS-U). Irritable bowel syndrome was significantly associated with young age [odds ratio (OR) = 0.87, 95% confidence interval (CI) 0.80-0.95], female gender (OR = 1.78, 95% CI 1.38-2.29), low body mass index (BMI) (OR = 0.95, 95% CI 0.92-0.99), and the presence of allergic disease (OR = 2.19, 95% CI 1.40-3.54). Analysis of IBS subtypes revealed that IBS-C was associated with young age and female gender; IBS-D with young age, low BMI, and drinking habit; IBS-M with female gender, smoking habits, and allergic diseases; and IBS-U with age, female gender, and allergic diseases.

CONCLUSIONS & INFERENCES

Irritable bowel syndrome was common and associated with young age, female gender, low BMI, and presence of allergic diseases in Japanese adults. Several differences were noted between the risk factors among different IBS subtypes.

The Traditional Japanese Medicine Rikkunshito Promotes Gastric Emptying via the Antagonistic Action of the 5-HT(3) Receptor Pathway in Rats

The traditional Japanese medicine rikkunshito ameliorates the nitric oxide-associated delay in gastric emptying. Whether rikkunshito affects gastric motility associated with 5-hydroxytryptamine (serotonin: 5-HT) receptors or dopamine receptors is unknown. We examined the effects of rikkunshito on the delay in gastric emptying induced by 5-HT or dopamine using the phenol red method in male Wistar rats. 5-HT (0.01–1.0 mg kg⁻¹, i.p.) dose dependently delayed gastric emptying, similar to the effect of the 5-HT₃ receptor agonist 1-(3-chlorophenyl) biguanide (0.01–1.0 mg kg⁻¹, i.p.). Dopamine also dose dependently delayed gastric emptying. The 5-HT₃ receptor antagonist ondansetron (0.04–4.0 mg kg⁻¹) and rikkunshito (125–500 mg kg⁻¹) significantly suppressed the delay in gastric emptying caused by 5-HT or 1-(3-chlorophenyl) biguanide. Hesperidin (the most active ingredient in rikkunshito) suppressed the 5-HT-induced delayed gastric emptying in a dose-dependent manner, the maximum effect of which was similar to that of ondansetron (0.4 mg kg⁻¹). The improvement obtained by rikkunshito or ondansetron in delaying gastric emptying was completely blocked by pretreatment with atropine. Rikkunshito appears to improve delay in gastric emptying via the antagonistic action of the 5-HT₃ receptor pathway.

Increased numbers of immature plasma cells in peripheral blood specifically overexpress chemokine receptor CXCR3 and CXCR4 in patients with ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease featuring infiltration by plasma cells producing immunoglobulins. We have reported previously the specific and significant proliferation of immature plasma cells in the inflamed colonic and pouch mucosa of UC patients. The aim of this study was to characterize peripheral blood immature plasma cells and the migration mechanisms of such immature plasma cells to inflamed sites in UC. The characteristics of peripheral blood immature plasma cells and chemokine receptor expression were examined by flow cytometry. Expression of mucosal chemokine was quantified using real-time reverse transcription-polymerase chain reaction and immunohistochemistry. The number of peripheral blood immature plasma cells was significantly higher in patients with active UC and active Crohn's disease (CD) than in healthy controls. The proportion of immature plasma cells was correlated positively with clinical activities of UC and CD. Many peripheral blood immature plasma cells were positive for CXCR3, CXCR4, CCR9 and CCR10. Expression of CXCR3 and CXCR4 in UC patients was significantly higher than in controls. CXCL9, CXCL10 and CXCL11 mRNA levels in colonic mucosa of inflamed IBD were higher than in controls. Immunofluorescence study also showed abundant CXCR3-positive immature plasma cells in the inflamed colonic mucosa of UC. Increased numbers of immature plasma cells may migrate towards inflammatory sites of UC via the CXCR3 axis, and may participate in UC pathogenesis.

Potential application of arginine in interaction analysis

Aqueous solution of 0.1-2 M arginine at mildly acidic to neutral pH is widely used in biotechnology and protein research, including protein refolding, purification, and formulation. This is largely because of its ability to suppress non-specific protein-protein and protein-surface interactions. Here we propose potential applications of arginine in interaction analysis for proteins. One of the important goals of such analysis is discovery of small molecule antagonistic or agonistic ligands that bind to target proteins and thereby modulate their function. Such research is often hampered by the low solubility of the small molecules, the instability of target proteins and the non-specific protein-ligand interactions. Aqueous arginine solution increases the solubility of small molecules, which should give an alternative to conventional dissolution method of small molecules by organic solvents. Arginine may also directly impact on the analysis of protein-protein or protein-ligand interactions by suppressing weak non-specific interactions.