Muscarinic acetylcholine receptor subtype 4 is essential for cholinergic stimulation of duodenal bicarbonate secretion in mice - relationship to D cell/somatostatin

We investigated the roles of muscarinic (M) acetylcholine receptor subtype in the cholinergic stimulation of duodenal HCO3(-) secretion using knockout (KO) mice. Wild-type and M1-M5 KO C57BL/6J mice were used. The duodenal mucosa was mounted on an Ussing chamber, and HCO3(-) secretion was measured at pH 7.0 using a pH-stat method in vitro. Carbachol (CCh) or other agents were added to the serosal side. CCh dose-dependently stimulated HCO3(-) secretion in wild-type mice, and this effect was completely inhibited in the presence of atropine. The HCO3(-) response to CCh in wild-type mice was also inhibited by pirenzepine (M1 antagonist), 4DAMP (M3 antagonist), and tropicamide (M4 antagonist), but not by methoctramine (M2 antagonist). CCh stimulated HCO3(-) secretion in M2 and M5 KO animals as effectively as in WT mice; however, this stimulatory effect was significantly attenuated in M1, M3, and M4 KO mice. The decrease observed in the CCh-stimulated HCO3(-) response in M4 KO mice was reversed by the co-application of CYN154806, a somatostatin receptor type 2 (SST2) antagonist. Octreotide (a somatostatin analogue) decreased the basal and CCh-stimulated secretion of HCO3(-) in wild-type mice. The co-localized expression of somatostatin and M4 receptors was confirmed immunohistologically in the duodenum. We concluded that the duodenal HCO3(-) response to CCh was directly mediated by M1/M3 receptors and indirectly modified by M4 receptors. The activation of M4 receptors was assumed to inhibit the release of somatostatin from D cells and potentiate the HCO3(-) response by removing the negative influence of somatostatin via the activation of SST2 receptors.

Macrophage- and RIP3-dependent inflammasome activation exacerbates retinal detachment-induced photoreceptor cell death

Detachment of photoreceptors from the retinal pigment epithelium is seen in various retinal disorders, resulting in photoreceptor death and subsequent vision loss. Cell death results in the release of endogenous molecules that activate molecular platforms containing caspase-1, termed inflammasomes. Inflammasome activation in retinal diseases has been reported in some cases to be protective and in others to be detrimental, causing neuronal cell death. Moreover, the cellular source of inflammasomes in retinal disorders is not clear. Here, we demonstrate that patients with photoreceptor injury by retinal detachment (RD) have increased levels of cleaved IL-1β, an end product of inflammasome activation. In an animal model of RD, photoreceptor cell death led to activation of endogenous inflammasomes, and this activation was diminished by Rip3 deletion. The major source of Il1b expression was found to be infiltrating macrophages in the subretinal space, rather than dying photoreceptors. Inflammasome inhibition attenuated photoreceptor death after RD. Our data implicate the infiltrating macrophages as a source of damaging inflammasomes after photoreceptor detachment in a RIP3-dependent manner and suggest a novel therapeutic target for treatment of retinal diseases.

Significance of serum Zn-α2-glycoprotein for the regulation of blood pressure

Zn-α2-glycoprotein (ZAG) (molecular weight=41 kDa) is one component in the α2 fraction of human plasma, and is reported to be associated with several diseases, such as cancers and metabolic syndromes. ZAG is also considered to be an important modulator of lipid metabolism. However, little is known about the correlation of serum ZAG levels with indicators of metabolic syndrome. Serum ZAG concentrations analyzed by enzyme-linked immunoassay were positively correlated with systolic and diastolic blood pressure in 326 subjects (236 males and 90 females) aged 17-79 years who had an annual health examination. By luciferase reporter and electrophoretic mobility shift assays, the core promoter region to regulate the ZAG gene expression was found to exist between -110 and -101. The transcription factor Sp1 interacted with this region, and Sp1 knockdown experiments showed that Sp1 critically regulated ZAG expression. Furthermore, ZAG increased the active form of RhoA, which was determined by pull-down assay. Increased serum ZAG concentrations induced, at least partly, by Sp1 may cause an increase in vascular tone through the activation of RhoA and contribute to elevated blood pressure.

Non-physician communities in Japan: are they still disadvantaged?

INTRODUCTION

Non-physician community' (NPC) is a policy term that indicates a medically underserved area in Japan. Designated NPCs are politically targeted as the foci of medical resource allocation. NPC is defined as a specified district where 50 or more persons dwell within a geographic diameter of 4 km and medical care is not easily accessible. The definition of NPC was first introduced in 1960 and has been unchanged for more than half a century despite radical social changes in rural Japan. This study examines whether designated NPCs are still more disadvantaged in terms of geographical access to healthcare in comparison to other communities.

METHODS

Hiroshima prefecture, which has the largest number of NPCs in terms of tertiary healthcare areas of Japan, was used as the study area. Targeted communities were all the NPCs in the prefecture, and, as controls, two community groups were selected: non-NPC adjacent to NPC, and municipal center. We measured driving time from NPCs and control communities to the nearest healthcare facilities, which were classified into the following two types: primary or secondary care facilities (n=2636) and tertiary care facilities (equal to tertiary emergency care centers; n=6). We further calculated the driving time to the nearest facilities for secondary emergency care (n=246) extracted from the 2636 primary or secondary care facilities.

RESULTS

The median driving times to the nearest primary or secondary healthcare facility for NPC, non-NPC, and municipal center were 11 minutes, 11 minutes, and 1 minute, respectively; the times to a tertiary healthcare facility (equal to an accident and emergency care center) were 80 minutes, 84 minutes, and 68 minutes, respectively; and the times to a secondary emergency care facility were 24 minutes, 18 minutes, and 15 minutes, respectively. Although a municipal center was significantly more advantageous in driving time compared to a primary or secondary care facility, the disadvantage of a NPC in access was no more obvious than an adjacent non-NPC for any type of healthcare facility.

CONCLUSIONS

NPCs had a disadvantage in access time to primary, secondary and tertiary medical care compared with a municipal center. NPCs, however, did not have a greater access disadvantage in comparison to adjacent rural communities for any type of medical facility. As such, future resource allocation policies in Japan need to redefine medically underserved communities.

Effect of heat stress soon after muscle injury on the expression of MyoD and myogenin during regeneration process

Heat stress could promote skeletal muscle regeneration. But, in the regeneration process, effects of heat stress on myogenic cells and the regulating factors is unknown. Therefore, Influences of heat stress soon after injury on distribution of the myogenic cells and chronological changes in expression of MyoD and myogenin were examined. The first peak of MyoD expression was temporally correlated with the time when proliferating satellite cells began to appear, and the rapid decline of the MyoD expression from the first peak, with the appearance time of myoblasts, respectively in both the non-Heat and Heat groups. The first peak of myogenin expression was temporally correlated with the time when multinuclear cells began to form in the both groups. Due to the heat stress, proliferation and differentiation of myogenic cells and chronological changes in these factors were accelerated one day earlier than in the non-Heat group. As MyoD and myogenin are regulating factor of proliferation and differentiation, heat stress soon after the muscle injury could accelerate the proliferation and differentiation of myogenic cells and the expression of their regulating factors MyoD and myogenin.

TAK-875, a GPR40/FFAR1 agonist, in combination with metformin prevents progression of diabetes and β-cell dysfunction in Zucker diabetic fatty rats

BACKGROUND AND PURPOSE

TAK-875, a selective GPCR40/free fatty acid receptor 1 agonist, improves glycaemic control by increasing glucose-dependent insulin secretion. Metformin is a first-line drug for treatment of type 2 diabetes that improves peripheral insulin resistance. Based on complementary mechanism of action, combining these agents is expected to enhance glycaemic control. Here, we evaluated the chronic effects of TAK-875 monotherapy and combination therapy with metformin in diabetic rats.

EXPERIMENTAL APPROACH

Long-term effects on glycaemic control and β-cell function were evaluated using Zucker diabetic fatty (ZDF) rats, which develop diabetes with hyperlipidaemia and progressive β-cell dysfunction.

KEY RESULTS

Single doses of TAK-875 (3-10 mg·kg(-1) ) and metformin (50-150 mg·kg(-1) ) significantly improved both postprandial and fasting hyperglycaemia, and additive improvements were observed in their combination. Six-week treatment with TAK-875 (10 mg·kg(-1) , b.i.d.) significantly decreased glycosylated Hb (GHb) by 1.7%, and the effect was additively enhanced by combination with metformin (50 mg·kg(-1) , q.d.; GHb: -2.4%). This improvement in glycaemic control in the combination group was accompanied by significant 3.2-fold increase in fasting plasma insulin levels. Pancreatic insulin content was maintained at a level comparable to that in normal rats by combination treatment (vehicle: 26, combination: 67.1; normal lean: 69.1 ng·mg(-1) pancreas) without affecting pancreatic glucagon content. Immunohistochemical analyses revealed normal morphology, enhanced pancreas duodenum homeobox-1 expression and increased PCNA-positive cells in islets of the combination group.

CONCLUSION AND IMPLICATIONS

Our results indicate that combination therapy with TAK-875 and metformin could be a valuable strategy for glycaemic control and β-cell preservation in type 2 diabetes.

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.

Lipoprotein-associated phospholipase A2 regulates macrophage apoptosis via the Akt and caspase-7 pathways

AIM

Mutations in lipoprotein-associated phospholipase A2 (Lp-PLA2) are related to atherosclerosis. However, the molecular effects of Lp-PLA2 on atherosclerosis have not been fully investigated. Therefore, this study attempted to elucidate this issue.

METHODS

Monocytes were isolated from randomly selected healthy male volunteers according to each Lp-PLA2 genotype (wild-type Lp-PLA2 [Lp-PLA2 (V/V)], the heterozygous V279F mutation [LpPLA2 (V/F)] and the homozygous V279F mutation [Lp-PLA2 (F/F)]) and differentiated into macrophages. The level of apoptosis in the macrophages following incubation without serum was measured using the annexin V/propidium iodide double staining method, and the underlying mechanisms were further examined using a culture cell line.

RESULTS

The average plasma Lp-PLA2 concentration [Lp-PLA2 (V/V): 129.4 ng/mL, Lp-PLA2 (V/F): 70.7 ng/mL, Lp-PLA2 (F/F): 0.4 ng/mL] and activity [Lp-PLA2 (V/V): 164.3 nmol/min/mL, LpPLA2 (V/F): 100.9 nmol/min/mL, Lp-PLA2 (F/F): 11.6 nmol/min/mL] were significantly different between each genotype, although the basic clinical characteristics were similar. The percentage of apoptotic cells was significantly higher among the Lp-PLA2 (F/F) macrophages compared with that observed in the Lp-PLA2 (V/V) macrophages. This induction of apoptosis was independent of the actions of acetylated low-density lipoproteins. In addition, the transfection of the expression plasmid of V279F mutant Lp-PLA2 into Cos-7 cells or monocyte/macrophage-like U937 cells promoted apoptosis. The knockdown of Lp-PLA2 also increased the number of apoptotic cells. Among the cells expressing mutant Lp-PLA2, the caspase-7 activity was increased, while the activated Akt level was decreased.

CONCLUSIONS

The V279F mutation of Lp-PLA2 positively regulates the induction of apoptosis in macrophages and Cos-7 cells. An increase in the caspase-7 activity and a reduction in the activated Akt level are likely to be involved in this phenomenon.

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.

[Case of lymphomatoid gastropathy detected during follow-up after chemoradiotherapy for esophageal cancer]

A man in his 70s underwent chemoradiotherapy for squamous cell carcinoma of the esophagus in 2009. A follow-up gastroendoscopy performed 3 years later revealed a reddish depressed lesion in the greater curvature of the middle stomach body. On the basis of histological and immunohistochemical findings and clinical features, including endoscopic findings, a diagnosis of lymphomatoid gastropathy was made. Follow-up studies revealed a decrease in the size of the lesion and the development of chronic gastritis. Although lymphomatoid gastropathy is rare, recognition of this disease is important because misdiagnosis as lymphoma may lead to unnecessary radical therapeutic procedures.

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.

Rurality and participation in mass preventive health services: a nationwide descriptive study

People's engagement in community activities is reportedly stronger in rural areas than in urban areas. However, it is unknown whether this affects the health-seeking behaviour of residents in rural communities. We examined whether the rurality-related index of a community was associated with the participation rate of residents in community-based preventive health services. Based on the national census data on all the 1816 municipalities in Japan in 2007, the correlation was evaluated between the participation rate in cancer screening (stomach cancer, colorectal cancer) or influenza vaccination programmes among those older than 65, and each of the municipality-level variables. The correlations were examined by simple correlation and multiple regression analyses. The correlations were also evaluated between voting rate (a parameter of people's engagement in community activities) and each municipality-level variable with multiple regression analysis. Simple correlation analysis showed that the population density was negatively correlated with the participation rate of all (stomach cancer, colorectal cancer, and influenza) preventive programmes (r = -0.367, -0.171 and -0.188, respectively; each p < 0.001). The significant correlations were maintained even after adjustment for other socioeconomic factors in multiple regression analysis in stomach cancer screening and influenza vaccination (beta = -0.279 and -0.133, respectively: each p < 0.05). Population density was negatively correlated with voting rate (beta = -0.488: p < 0.001). Residents in rural communities were more likely to participate in community-based mass preventive services and were more actively engaged in political activities than their urban counterparts. These results suggest that rural residents have a stronger sense of community, and this could potentially facilitate residents' engagement in mass preventive services.

Do rural and remote areas really have limited accessibility to health care? Geographic analysis of dialysis patients in Hiroshima, Japan

INTRODUCTION

For an equitable distribution of health resources, resource-allocation policies focus on rural and also remote areas, assuming that these areas are underserved. However, definitions of 'rural' and 'remote' vary, and are not necessarily synonymous with 'underserved'. This Japanese study evaluated the association between the rurality/remoteness of the community in which a patient lives and his/her geographic accessibility to dialysis facilities.

METHODS

Based on 1867 communities (census blocks) in Hiroshima Prefecture, Japan, predictive powers of five community-level rural/remote parameters (population size, population density, elderly rate, agriculture rate, and distance to the nearest city) were evaluated to identify communities where dialysis patients had a longer commute time to dialysis facilities. The proportion of low-access communities was examined when those communities were merged to form larger geographic units (four-level stepwise merger). One-way driving times of dialysis patients were used as the access parameter of a community and were calculated using geographic information systems based on the addresses of all the 7374 patients certified by municipalities as having renal disability, and on the addresses and capacities of all 98 dialysis facilities in Hiroshima.

RESULTS

The average driving time was negatively correlated with population and population density, and positively correlated with elderly rate, agriculture rate, and distance to nearest city. When low-access was defined as >20, >30 & >40 min driving time, all rural/remote parameters showed better sensitivities (range 63.5-94.9%) than specificities (55.2-77.9%) to identify low-access communities, and positive predictive values were less than 50% for most parameters. When low-access was defined as >30 min driving time, the proportion of low-access communities substantially decreased when the geographic unit was expanded. In the administrative 'rural' area, the largest geographic unit, the percentage of low-access communities was 30%.

CONCLUSIONS

In any definition of 'rural/remote', and in any definition of 'low-access', the rural/remote areas contain a substantial proportion of high-access communities. In addition, a substantial proportion of low-access communities was excluded from rural/remote areas. The accuracy of the term 'low-access' deteriorated when the geographic unit of analysis was expanded. In order to identify underserved areas precisely, it is necessary to set the geographic unit of analysis as small as possible and measure the geographic accessibility itself, rather than designate some areas as 'rural' or 'remote', based on conventional geographic/demographic/distance parameters.