Cinacalcet, a calcimimetic, prevents nonsteroidal antiinflammatory drug-induced small intestinal damage in rats

The extracellular calcium-sensing receptor (CaSR), a G protein-coupled cell receptor cloned from bovine parathyroid, has been demonstrated to play a regulatory role in various functions of the gastrointestinal tract. In the present study, we examined the effect of cinacalcet, a drug that acts as a calcimimetic through the allosteric activation of CaSR, on the loxoprofen-induced small intestinal lesions and investigated the mechanisms involved in the protective action. Male Sprague-Dawley rats were used without fasting. The animals were administered loxoprofen p.o. and euthanized 24 hours later and the intestinal mucosa was examined for lesions. Cinacalcet was given p.o. twice, 30 min before and 6 h after loxoprofen. Loxoprofen caused hemorrhagic lesions in the small intestine, accompanied by the upregulation of enterobacterial invasion, myeloperoxidase (MPO) activity and inducible nitric oxide synthase (iNOS)/tumor necrosis factor α (TNF-α) expression as well as the downregulation of Muc2 expression. Prior administration of cinacalcet dose-dependently and significantly reduced the severity of these lesions in response to loxoprofen, with concomitant suppression of the changes in bacterial invasion, iNOS/TNF-α as well as Muc2 expression, and myeloperoxidase activity. Cinacalcet also significantly reversed a decrease in mucus secretion and fluid secretion in the small intestine caused by loxoprofen, but had no effect on the intestinal hypermotility or prostaglandin E₂ deficiency caused by loxoprofen. These results suggest that cinacalcet protects the small intestine against loxoprofen-induced damage, and this effect may be functionally associated with an increase in fluid secretion and a reversal of downregulation of Muc2 expression caused by loxoprofen, resulting in suppression of bacterial invasion and iNOS/TNF-α expression, the major pathogenic events in nonsteroidal antiinflammatory drugs-induced small intestinal ulceration.

ROS evaluation for a series of CNTs and their derivatives using an ESR method with DMPO

Carbon nanotubes (CNTs) are important materials in advanced industries. It is a concern that pulmonary exposure to CNTs may induce carcinogenic responses. It has been recently reported that CNTs scavenge ROS though non-carbon fibers generate ROS. A comprehensive evaluation of ROS scavenging using various kinds of CNTs has not been demonstrated well. The present work specifically investigates ROS scavenging capabilities with a series of CNTs and their derivatives that were physically treated, and with the number of commercially available CNTs. CNT concentrations were controlled at 0.2 through 0.6 wt%. The ROS scavenging rate was measured by ESR with DMPO. Interestingly, the ROS scavenging rate was not only influenced by physical treatments, but was also dependent on individual manufacturing methods. Ratio of CNTs to DMPO/ hydrogen peroxide is a key parameter to obtain appropriate ROS quenching results for comparison of CNTs. The present results suggest that dangling bonds are not a sole factor for scavenging, and electron transfer on the CNT surface is not clearly determined to be the sole mechanism to explain ROS scavenging.

Prophylactic effect of egualen sodium, a stable azulene derivative, on gastrointestinal damage induced by ischemia/reperfusion, double antiplatelet therapy and loxoprofen in rats

We examined the effect of egualen, a stable azulene derivative, against gastric damage induced by ischemia/reperfusion (I/R), gastric bleeding induced by double antiplatelet therapy with aspirin (ASA) plus clopidogrel, and small intestinal damage generated by loxoprofen, and investigated the possible mechanisms involved in its protective action. Male C57BL/6 mice or SD rats were used under urethane anesthesia (gastric lesions) or in a conscious (intestinal lesions) state. I/R-induced gastric injury was produced in mice by clamping the celiac artery for 30 min, followed by reperfusion for 60 min. Gastric bleeding was induced in rats by luminal perfusion with 25 mM ASA+50 mM HCl for 2 hours in the presence of clopidogrel (30 mg/kg). To produce small intestinal lesions the rats were given loxoprofen (60 mg/kg) p.o. and killed 24 hours later. Egualen was given i.d. 60 min before I/R or ASA perfusion, while given p.o. twice 30 min before and 6 hours after loxoprofen. Egualen significantly prevented the I/R-induced gastric damage, and the effect was equivalent to that of seratrodast (TXA2 antagonist). This agent also significantly suppressed gastric bleeding induced by ASA plus clopidogrel, similar to PGE2. Likewise, egualen significantly prevented loxoprofen-induced damage in the small intestine, accompanied by an increase in the secretion of mucus and suppression of bacterial invasion as well as iNOS expression. These results suggest that egualen has a prophylactic effect against various lesions in the gastrointestinal mucosa, probably through its characteristic pharmacological properties, such as TXA2 antagonistic action, local mucosal protection, and stimulation of mucus secretion.

CD44 with variant exons 8-10 in colorectal tumors

Using a fusion protein encoded by variant exon (v) 8-10 of CD44, a monoclonal antibody (mAb) 44-1V reactive with v9 product was generated. Western immunoblots and reverse transcriptase-polymerase chain reaction/Southern blot revealed that a 130 kilodalton component containing v8-10 products was specifically expressed in colorectal and gastric cancer cell lines. Immunohistological examination of 179 pairs of colorectal cancer and normal tissues revealed that about 47% of cancers expressed the CD44 variant (CD44v8-10), and its expression correlated with hematogenous and lymph node metastasis. These findings suggest the usefulness of CD44v8-10 in the prediction of colorectal cancer metastasis.

Sialyl-lewis-x antigen immunoreaction of colorectal-cancer and its relationship to hematogenous metastasis

The adhesion of cancer cells to endothelial cells of the target organ is one of the most important steps of hematogenous metastasis. Especially, sialyl Le(X) plays an important role in defining the metastasis. The expression of sialyl Le(X) antigen in colorectal cancer and its usefulness not only as an indicator of metastatic potential but also as a prognostic factor was studied immunohistochemically. Fifty-five (32.4%) sialyl Le(X) antigen-positive tumors were found in 170 colorectal cancers. There was a significant correlation between the expression of sialyl Le(X) antigen and the histological tumor type, venous invasion, lymph node metastasis, as well as liver metastasis. Hematogenous metastases were significantly more frequent in patients with sialyl Le(X)-positive tumor than in those with sialyl Le(X)-negative tumor; and prognosis was significantly poorer in the former. The results suggest that sialyl Le(X) antigen plays a role in hematogenous metastasis of colorectal cancer, and that the expression of sialyl Le(X) is associated with poor prognosis.

Small molecule antibody targeting HLA class I inhibits myeloma cancer stem cells by repressing pluripotency-associated transcription factors

Cancer stem cells have been proposed to be responsible for tumorigenesis and recurrence in various neoplastic diseases, including multiple myeloma (MM). We have previously reported that MM cells specifically express HLA class I at high levels and that single-chain Fv diabody against this molecule markedly induces MM cell death. Here we investigated the effect of a new diabody (C3B3) on cancer stem cell-like side population (SP) cells. SP fraction of MM cells highly expressed ABCG2 and exhibited resistance to chemotherapeutic agents; however, C3B3 induced cytotoxicity in both SP cells and main population (MP) cells to a similar extent. Moreover, C3B3 suppressed colony formation and tumorigenesis of SP cells in vitro and in vivo. Crosslinking of HLA class I by C3B3 mediated disruption of lipid rafts and actin aggregation, which led to inhibition of gene expression of β-catenin and pluripotency-associated transcription factors such as Sox2, Oct3/4 and Nanog. Conversely, knockdown of Sox2 and Oct3/4 mRNA reduced the proportion of SP cells, suggesting that these factors are essential in maintenance of SP fraction in MM cells. Thus, our findings reveal that immunotherapeutic approach by engineered antibodies can overcome drug resistance, and provide a new basis for development of cancer stem cell-targeted therapy.

Gas mediators involved in modulating duodenal HCO3(-) secretion

The secretion of HCO3(-) in the duodenum is increased by mucosal acidification, and this process is modulated by gas mediators such as nitric oxide (NO), hydrogen sulfide (H2S), and carbon monoxide (CO), in addition to prostaglandins (PGs). The secretion is increased by NOR3 (NO donor), NaHS (H2S donor), and CORM-2 (CO donor). The HCO3(-) responses to NOR3 and CORM-2 are attenuated by indomethacin, while that to NaHS is mitigated by indomethacin and L-NAME as well as sensory deafferentation. NOR3 and CORM-2 increase mucosal PGE2 production, while H2S increases mucosal PGE2 content and luminal NO release. The HCO3(-) response to mucosal acidification is attenuated by indomethacin, propargylglycine, and SnPP, each inhibiting PG, H2S and CO production, respectively. The acid-induced duodenal damage is worsened when either PG, H2S or CO is lacking. These findings suggest that 1) NO, H2S, and CO, generated endogenously or exogenously, stimulate HCO3(-) secretion in the duodenum; 2) the stimulatory action of NO and CO is mediated, at least partly, by endogenous PGs, while that of H2S is mediated by PGs and NO as well as sensory neurons; 3) these gas mediators are involved in the local regulation of acid-induced HCO3(-) secretion, in addition to endogenous PGs; 4) the acid-induced duodenal damage is worsened by agents inhibiting the endogenous production of NO, H2S or CO. It is assumed that these gas mediators play a role in maintaining the integrity of the duodenal mucosa by modulating the secretion of HCO3(-).

Management of NSAID/aspirin-induced small intestinal damage by GI-sparing NSAIDs, anti-ulcer drugs and food constituents

Recent advances in endoscopic techniques such as capsule endoscopy have revealed that aspirin and other nonsteroidal antiinflammatory drugs (NSAIDs) often cause mucosal lesions not only in the upper gastrointestinal tract, but also in the small intestine in humans. Gastric and duodenal lesions caused by NSAIDs can be treated with anti-secretory agents such as proton pump inhibitors or histamine H2-receptor antagonists; however, these drugs are ineffective in treating NSAID-induced lesions in the small intestine. Furthermore, there are few effective agents for the treatment of small intestinal lesions. Therefore, identification of effective therapies for the treatment of NSAID/aspirin-induced small intestinal lesions remains an urgent priority. In the present review, we focus on novel pharmacological treatments to prevent or reduce NSAID-induced intestinal lesions, i.e., 1) GI-sparing NSAIDs (NO- or H2S-NSAIDs, NSAIDs mixed with phosphatidylcholine); 2) anti-ulcer drugs such as mucosal protective agents (misoprostol, rebamipide, teprenone, etc.) and anti-secretory agents (lansoprazole, etc.); 3) antibiotics (metronidazole) and probiotics (Lactobacillus sp.); and 4) food constituents (lactoferrin and soluble dietary fibers). We surveyed data from clinical trials evaluating these novel treatments. Also reviewed herein were the pros and cons of the novel protective methods from the standpoint of safety, efficacy, convenience, and cost.

Does the insufficient supply of physicians worsen their urban-rural distribution? A Hiroshima-Nagasaki comparison

INTRODUCTION

Studies have suggested that a rapid increase in physicians does not necessarily change an urban-rural inequity in their distribution. However, it is unknown whether an insufficient supply of physicians worsens an inequity. Spatial competition and attraction-repulsion hypotheses were applied to the geographic distribution of physicians during a time of insufficient physician supply in Japan.

METHODS

Trends of physician distribution as well as urban-rural physician flow were compared using Hiroshima Prefecture which had the lowest increase in physician-to-population ratios between 2002 and 2008 (2.7%), and Nagasaki Prefecture where the increase was one of the highest (12.0%) among the 47 Japanese prefectures.

RESULTS

The Gini coefficient of physicians compared with population in Hiroshima increased by 4.1%. Movement toward inequity was greater in Hiroshima compared with Nagasaki where the increase was 2.5%. Approximately 245 physicians or 18.8% moved from rural to urban locations in Hiroshima compared with 143 (14.6%) for Nagasaki (p=0.01). In contrast, 228 (7.6%) urban physicians moved to rural areas in Hiroshima compared with 175 (11.6%) in Nagasaki (p<0.001).

CONCLUSIONS

In a time of insufficient supply of physicians, a region with a smaller increase in physicians may experience worsening of the urban-rural distribution of physicians compared with a region where there is a more rapid increase in physicians. One strategy for achieving a more equitable distribution of physicians is to increase in the physician supply relative to demand in order to stimulate competition among urban physicians and maintain the power equilibrium between attraction-to and repulsion-from urban areas.