Two Types of Stretch-Activated Channels Coexist in the Rabbit Corneal Epithelial Cell

Ion channels contribute to the regulation of cellular function through control of the membrane potential and intracellular concentration of various ions. We examined stretch-activated channels in the corneal epithelial cell. Patch clamping was applied to enzymatically dissociated corneal epithelial cells to characterize their stretch-activated ion channels. The plasma membrane was stretched by applying suction to the patch pipette in cell-attached or inside-out patch configuration. The ion selectivity, voltage-dependence, and stretch-dependence were examined. Two kinds of stretch-activated channel events were observed; the previously-reported large conductance (L) channel and a novel small conductance (S) channel. The probability of recording L vs. S channels in the cell-attached configuration was about 2:1. The L channel was potassium selective with single channel conductance (γ) of about 160 pS under the symmetrical (150 mmK⁺) solution. The S channel was permeable to Na⁺and K⁺with γof about 20 pS under the same conditions. Both L and S channels showed little activity in the absence of suction applied to the recording pipette. Channel activity was evoked by suction (negative pressure) stronger than -20 mmHg in both channels. The open probability (P_o) and the mean current increased in proportion to further applied stretch and did not saturate for applied suction as strong as -80 mmHg, the pressure at which the gigaseal started to break. Thus, two types of stretch-activated channels coexist in corneal epithelial cells; a potassium-selective L channel and non-selective S channel. The contribution of these channels to the membrane potential is discussed.     

Application of a Remodeled Stiegmann-ligator to Esophageal Varix

Abstract: The Stiegmann-ligator has been recently proved to be useful for the treatment of esophageal varices. With those ligators, however, we found difficulty in performing ligation when the pathological change was on the tangent line or relatively large, such as F₃, or associated with concentrated RC signs. To overcome these problems, we modified the Stiegmann O-ring ligator by diagonally cutting the tip of the inner sleeve. Using this ligator, we conducted some animal-model experiments and clinical trials. In all cases, the remodeled ligator covered a wider range of lesions. We no longer encountered difficulties in performing ligation with the remodeled ligator when pathological changes were on the tangent line. The procedure did not cause any complications apart from temporary chest discomfort after surgery.     

Relationship of insulin clearance and secretion to insulin sensitivity in non-diabetic Mexican Americans

The antecedents of type II diabetes, while still controversial, are thought to involve decreased insulin sensitivity and compensatory hypersecretion of insulin. Mexican Americans have a three-fold excess risk of type II diabetes and non-diabetic Mexican Americans are characterized by hyperinsulinaemia and insulin resistance. Few data exist, however, on whether there are defects in insulin secretion and/or clearance in this population. We examined insulin sensitivity, secretion and clearance using combined insulin and C-peptide measurements analysed by the minimal model technique of Bergman and colleagues in 10 non-obese, normoglycaemic Mexican Americans and 11 age, sex and obesity-matched non-Hispanic whites. Mexican Americans had significantly decreased insulin sensitivity (SI 4.06 s. 7.56, P = 0.017), higher first phase insulin secretion (1.03 nM vs. 0.72 nM) and decreased insulin clearance (0.099 vs. 0.161) than non-Hispanic whites. Thus, normal Mexican Americans have higher rather than lower insulin secretion suggesting that lower insulin sensitivity may be an early defect in this ethnic group. In addition, they have reduced insulin clearance. Moreover, insulin sensitivity and insulin clearance were positively correlated. We thus speculate that decreased insulin clearance may represent a further autoregulatory mechanism in addition to increased insulin secretion to compensate for decreased insulin sensitivity.     

Solitary juvenile polyp developing adenocarcinoma with submucosal invasion

Solitary juvenile polyps are generally non‐neoplastic hamartomatous polyps. Inflammation is suggested as the cause of proliferation and progression of these polyps, and adenomatous and carcinomatous changes are rare. We report a rare case of a solitary juvenile polyp with malignant transformation that developed in the sigmoid colon of a 12‐year‐old boy. A 3 cm, pedunculated polyp was endoscopically resected, and histologic evaluation revealed the characteristic features of a juvenile polyp. However, mucous‐filled ectatic glandular spaces were lined by mucin‐secreting columnar epithelial cells with atypical change, and an admixture of adenocarcinoma invading the submucosa was confirmed. The histologic features may suggest the involvement of the adenoma–carcinoma sequence in the development of adenocarcinoma in the present case. Although rare, solitary juvenile polyps should develop adenocarcinoma and thorough histologic evaluation of the resected polyps is warranted to identify the adenomatous tissue.     

Defective suppressor function of spleen cells by neonatal thymectomy and persistence of experimental auto-immune hepatitis in mice

The effects of neonatal thymectomy on a model of auto-immune hepatitis prepared by immunizing A/J mice with syngeneic crude liver proteins were studied. Hepatitis was more severe in neonatally thymectomized mice (Group B) than in non-thymectomized controls (Group A). Changes in the hepatic lobules were reduced in both groups 3 months after the final immunization, but inflammation around the portal areas tended to persist in Group B; only this group showed frequent infiltration of mononuclear cells accompanied by destruction of the limiting plate in the portal area. The serum level of auto-antibody to liver-specific membrane lipoprotein complex (LSP) and delayed-type hypersensitivity (DTH) to LSP were higher in Group B than in Group A. The auto-antibody to LSP was positive in both groups 3 months after the final immunization. Although it was significantly reduced in Group A compared with the level 3 days after the final immunization, it remained high in Group B. Liver damage, production of the auto-antibody to LSP and DTH to LSP were reduced by adoptive transfer of normal murine spleen cells, but the spleen cells of neonatally thymectomized mice showed no such effects. These results suggest that normal spleen cells possess the capability of suppressing auto-immune hepatitis, and the defect of this capability due to T-cell dysfunction by neonatal thymectomy contributes to the promotion and persistence of auto-immune hepatitis.     

Reliability and validity of the Chinese version of the New Brief Job Stress Questionnaire (New BJSQ) among workers in China

This study aimed to develop the Chinese version of the New Brief Job Stress Questionnaire (New BJSQ) and investigate its reliability and validity. The survey was administered at two time-points separated by a two-week interval among Chinese workers. The Chinese version of the New BJSQ was developed according to the international guidelines. Cronbach’s alpha, intra-class correlation coefficients (ICCs), and Pearson correlation coefficient were calculated to assess the reliability. A variance explained by the first factor was calculated to examine factor-based validity, and confirmatory factor analysis was performed (CFA) to determine the construct validity. Baseline and follow-up analyses included 516 and 52 workers, respectively. In most scales, sufficient internal consistency and test-retest reliability were observed, and principal component analyses demonstrated that the first factor explained more than 50% proportion of the variance. CFA showed that the four-factor model (Job demands, Task-level job resources, Workgroup-level job resources, and Organizational-level job resources) demonstrated a moderate fit, similar to the original version. The Chinese version of New BJSQ showed good reliability and moderate validity. Future studies should explore content and construct validities and the factor structure of the Chinese version of the New BJSQ in more detail.     

The Acute and Chronic Toxicities of Nivalenol in Mice

The Acute and Chronic Toxicities of Nivalenol in Mice. Ryu,J.-C, Ohtsubo, K., Izumiy-ama, N., Nakamura, JL, Tanaka, T.,Yamamura, H., and Ueno, Y. (1988). Fundam. Appl Toxicol. 11,38–47. In an attempt to ascertain precisely the toxiceffects of nivalenol (N1V), we conducted the determination ofLD50 values, and interim kills during the carcinogenic studyin mice. LD50 values (mg/kg) of NIV in 6-week-old male ddY micewere determined as 38.9 (po), 7.4 (ip), 7.2 (sc), and 7.3 (iv).Seven-week-old female C57BL/6CrSlc SPF mice were fed diets containing0, 6, 12, and 30 ppm (mg/kg) NIV over 1 year, and were assessedfor effects on body weight gain, feed efficiency, terminai organweights, hematology, and histopathology. The rates of body weightgain and feed efficiency showed a good dose-dependent correlationin all experimental periods. Gross and histopathological evaluationof the liver, thymus, spleen, kidneys, stomach, adrenal glands,pituitary gland, ovaries, sternum, bone marrow, lymph node,brain, and small intestines with or without Peyer's patch portionfrom control and all NIV-exposed mice revealed that these tissueswere normal in appearance and in histopathological structure.Also, no changes were observed in the ultrastructural studieson the bone marrow. Dietary NIV did, however, cause dose-dependentdecreases of absolute organ weights (mg) and increases of relativeorgan weights (mg/g body weight) in the terminal organ weightsrecorded. A significant leukopenia was observed in the 30 ppmgroup at 6 months and in all NIV-treated groups at 1 year. Nomarked changes were observed in the other hematological parameters.These results indicated that 6 ppm or more of dietary NIV for1 year showed a characteristic toxic effect of trichothecenemycotoxins in mice.