Secretion of Mono- and Diacylglycerol Lipase fromPenicillium camembertiiU-150 bySaccharomyces cerevisiaeand Site-directed Mutagenesis of the Putative Catalytic Sites of the Lipase

Yeast cells carrying intronless mono- and diacylglycerol lipase (MDGL) genes, constructed by recombination of the genomic gene and cDNA, secreted MDGL into the culture supernatant. Most of the yeast MDGL were extensively glycosylated while they had a similar glyceride specificity to that of native MDGL. Site-directed mutagenesis was used to directly confirm the involvements in enzyme activity of the presumptive amino acid residues to form the catalytic center of MDGL. These residues were conserved in the primary structure alignment of a lipase family from filamentous fungi. Mutant lipase proteins in which Ser83, Ser145, or His259 was replaced with glycine were secreted by yeast transformants as inactive proteins. Mutant proteins replacing Asp199 with glycine or asparagine were not detected in the culture supernatant. Replacing other two highly conserved aspartic acids (at positions 232 and 243) with glycine did not render the enzyme inactive. These results indicate that Ser83, Ser145, and His259 in MDGL, are essential to enzyme activity. Asp199 is also likely to be involved.

Favorable results of early diagnosis by cervicothoracic computed tomography scans for descending necrotizing mediastinitis

OBJECTIVES

We studied results of early diagnosis by cervicothoracic computed tomography and early aggressive surgery for descending necrotizing mediastinitis.

METHODS

Between 1990 and 1999, 5 patients with descending necrotizing mediastinitis were surgically treated in our institute. Computed tomography scans confirmed mediastinitis in all cases, even though chest x-ray films demonstrated a widening mediastial shadow in only 2. Soon after surgical drainage of the deep neck infection and diagnosis of descending necrotizing mediastinitis, all patients underwent surgical mediastinal drainage. Mediastinitis was drained by thoracotomy in 1, managed thoracoscopically in 1 and cervicomediastinally drained in 3.

RESULTS

The outcome was favorable in all patients.

CONCLUSIONS

Early diagnosis by cervicothoracic computed tomography and early aggressive surgery for descending necrotizing mediastinitis are essential to favorable outcome.

Nutritional status and dysphagia risk among community-dwelling frail older adults

OBJECTIVES

Although the presence of dysphagia is a key determinant of nutritional status among older adults, few studies have focused on the association between malnutrition and dysphagia risk in community-dwelling frail older adults. This study estimated the prevalence of malnutrition and quantified the association between malnutrition and dysphagia risk among community-dwelling older Japanese adults requiring long-term care.

DESIGN

Cross-sectional study.

SETTING

This study was conducted with the cooperation of the Japan Dental Association and local dental associations in all 47 prefectures from January to February 2012.

PARTICIPANTS

Individuals aged ≥65 years capable of oral nutrient intake who were living at home and receiving home dental care and treatment.

MEASUREMENTS

Individual demographic characteristics and factors associated with health loss-related functional decline were obtained through interviews by home-visit dentists and self-administered questionnaires. Nutritional status and dysphagia risk were evaluated using the Mini Nutritional Assessment Short Form and the Dysphagia Risk Assessment for the Community-dwelling Elderly.

RESULTS

Among 874 respondents (345 men and 529 women), 24.6% were malnourished, 67.4% were at risk of malnutrition, and 8.0% were well nourished. Dysphagia risk was related to an increased likelihood of malnutrition at an old age, even after adjusting for covariates (PR = 1.30, 95% CI = 1.01-1.67).

CONCLUSION

Malnutrition is highly prevalent among community-dwelling frail older adults, and dysphagia risk is independently associated with malnutrition. Dysphagia may be an important predictor of malnutrition progression in aged populations.

Gastric cytoprotection by prostaglandin E₂ and prostacyclin: relationship to EP1 and IP receptors

Endogenous prostaglandins (PGs) play a role in modulating mucosal integrity and have various functions in the stomach, with E type PGs being the most effective. PGE₂ provides gastric cytoprotection against damage induced in rats by HCl/ethanol, indomethacin, or acid back-diffusion after barrier disruption. These effects were mimicked by EP1 agonists and/or attenuated by an EP1 antagonist, and disappeared in EP1 (-/-) mice. Furthermore, the adaptive cytoprotection induced by a mild irritant was attenuated by the EP1 antagonist and indomethacin. Capsaicin also provides gastric protection against HCl/ethanol, and its action was mitigated by indomethacin and sensory deafferentation, but not by the EP1 antagonist. Similar results were obtained using mice lacking various EP receptor subtypes; i.e., PGE₂ failed to provide both direct and adaptive cytoprotection in EP1 (-/-) mice, while capsaicin-induced protection was observed in EP1 (-/-) mice, but disappeared in IP (-/-) mice. The effects of PGE₂ on various gastric functions are mediated by different EP receptor subtypes; inhibition of acid secretion (EP3) and motility (EP1), stimulation of mucus secretion (EP4) and HCO₃⁻ secretion (EP1), and an increase in mucosal blood flow (EP2/EP4). In conclusion, the presence of EP1 receptors is essential to the protective action of PGE₂, either generated endogenously or administered exogenously, against HCl/ ethanol or indomethacin, and this action is functionally associated with the inhibition of gastric motility. Endogenous PGs also contribute to maintaining mucosal integrity after barrier disruption through an increase in mucosal blood flow, which occurs via sensory neurons influenced by activation of the EP1 receptor.

Functional variants in the thromboxane A2 receptor gene are associated with lung function in childhood-onset asthma

BACKGROUND

The thromboxane A2 receptor (TBXA2R) gene is associated with asthma, but no functional genetic variations are known to associate with the disease or its related phenotypes.

OBJECTIVE

To investigate the association of TBXA2R polymorphisms with asthma susceptibility and related phenotypes and to identify functionally relevant polymorphisms.

METHODS

We performed comprehensive sequencing of the TBXA2R gene in 48 Japanese control subjects and found a set of variants (SNP1 G>T rs2238634, SNP2 T>G rs2238633, SNP3 C>T rs2238632 and SNP4 G>A rs2238631) in intron 1 in linkage disequilibrium with c.795 T>C rs1131882, which was previously reported to be associated with asthma and related phenotypes. To investigate the effect of four common haplotypes (H1, H2, H3 and H4) on transcriptional activity, we performed a luciferase assay in primary bronchial smooth muscle cells (BSMCs) and human airway epithelial cells (BEAS-2B). We also studied the haplotype association with lung function, TBXA2R mRNA levels, and eosinophil fraction/count in peripheral blood in childhood-onset asthma patients and/or controls.

RESULTS

H2 and H4, containing minor alleles of SNP2 and SNP3, had significantly higher transcriptional activities than H1 consisting of major alleles (P < 0.001 in BSMCs and BEAS-2B). Homozygotes for redefined haplotype h2 corresponding to minor alleles of SNP2 and SNP3 were associated with lower lung function in childhood-onset asthma patients compared to other zygotes (baseline Forced expiratory volume in one second (FEV1)/ Forced vital capacity (FVC) and Forced expiratory flow between 25% and 75% of the FVC (%FEF(25-75%)): P = 0.00201 and 0.0128, respectively, and post-bronchodilator FEV1/FVC and %FEF(25-75%): P = 0.00224 and 0.0393 respectively). Haplotype h2 was also associated with higher mRNA levels in control peripheral blood cells and higher blood eosinophil fractions and counts in female controls.

CONCLUSIONS AND CLINICAL RELEVANCE

Genetic variants were identified in the TBXA2R gene that influenced transcriptional activity and were associated with asthma-related phenotypes. Thromboxane pathways may therefore play important roles in airway inflammation and remodelling in asthma patients.

5-HT₃ receptor antagonists ameliorate 5-fluorouracil-induced intestinal mucositis by suppression of apoptosis in murine intestinal crypt cells

BACKGROUND AND PURPOSE

Chemotherapeutic agents, including 5-fluorouracil (5-FU), frequently cause intestinal mucositis resulting in severe diarrhoea and morphological mucosal damage. 5-HT₃ receptor antagonists are clinically effective in the treatment of nausea and emesis during cancer chemotherapy. Therefore we here have examined the effects of 5-HT₃ receptor antagonists on 5-FU-induced intestinal mucositis in mice.

EXPERIMENTAL APPROACH

Intestinal mucositis was induced in male C57BL/6 mice by daily administration of 5-FU (50 mg·kg⁻¹) for 5 days. Effects of 5-HT₃ receptor antagonists, ramosetron (0.01-0.1 mg·kg⁻¹) and ondansetron (5 mg·kg⁻¹), on the accompanying histology, cytokine production and apoptosis were assessed.

KEY RESULTS

Continuous administration of 5-FU to mice caused severe intestinal mucositis, which was histologically characterized by the shortening of villi and destruction of intestinal crypts, accompanied by body weight loss and diarrhoea. Daily ramosetron administration dose-dependently reduced the severity of intestinal mucositis, body weight loss and diarrhoea. Similar beneficial effects were observed with ondansetron. The number of apoptotic, caspase-3- and caspase-8-activated cells increased 24 h after the first 5-FU administration, and these responses were reduced by ramosetron. The up-regulation of TNF-α, IL-1β and IL-6 following 5-FU treatment was also attenuated by ramosetron.

CONCLUSIONS AND IMPLICATIONS

5-HT₃ receptor antagonists ameliorated 5-FU-induced intestinal mucositis in mice, and this action could result from suppression of apoptotic responses in the intestinal crypt cells via inhibition of cytokine expression. Thus, 5-HT₃ receptor antagonists may be useful for preventing not only nausea and emesis but also intestinal mucositis during 5-FU chemotherapy.

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.