Succinate is a paracrine signal for liver damage

BACKGROUND/AIMS: A G-protein-coupled succinate receptor has recently been identified in several tissues, including the liver. The objectives of this work were to determine the hepatic cell types that express this receptor and to determine its physiological role. METHODS: Expression and distribution of the succinate receptor was determined by RT-PCR and confocal immunofluorescence. Biochemical assays were used to measure succinate and cAMP. Cytosolic Ca2+ was monitored in single cells by time-lapse imaging. Western blot was used to study the effect of succinate on activation of hepatic stellate cells. RESULTS: The succinate receptor was expressed in quiescent hepatic stellate cells, and expression decreased with activation. Ischemia induced release of succinate in isolated perfused livers. In contrast to what is observed in cell expression systems, succinate did not inhibit cAMP production or increase cytosolic Ca2+ in primary hepatic stellate cells. However, succinate accelerated stellate cell activation. CONCLUSIONS: Hepatic stellate cells express the succinate receptor. Succinate may behave as a paracrine signal by which ischemic hepatocytes trigger stellate cell activation.     

Lipid rafts establish calcium waves in hepatocytes

BACKGROUND & AIMS: Polarity is critical for hepatocyte function. Ca(2+) waves are polarized in hepatocytes because the inositol 1,4,5-trisphosphate receptor (InsP3R) is concentrated in the pericanalicular region, but the basis for this localization is unknown. We examined whether pericanalicular localization of the InsP3R and its action to trigger Ca(2+) waves depends on lipid rafts. METHODS: Experiments were performed using isolated rat hepatocyte couplets and pancreatic acini, plus SkHep1 cells as nonpolarized controls. The cholesterol depleting agent methyl-beta-cyclodextrin (mbetaCD) was used to disrupt lipid rafts. InsP3R isoforms were examined by immunoblot and immunofluorescence. Ca(2+) waves were examined by confocal microscopy. RESULTS: Type II InsP3Rs initially were localized to only some endoplasmic reticulum fractions in hepatocytes, but redistributed into all fractions in mbetaCD-treated cells. This InsP3R isoform was concentrated in the pericanalicular region, but redistributed throughout the cell after mbetaCD treatment. Vasopressin-induced Ca(2+) signals began as apical-to-basal Ca(2+) waves, and mbetaCD slowed the wave speed and prolonged the rise time. MbetaCD had a similar effect on Ca(2+) waves in acinar cells but did not affect Ca(2+) signals in SkHep1 cells, suggesting that cholesterol depletion has similar effects among polarized epithelia, but this is not a nonspecific effect of mbetaCD. CONCLUSIONS: Lipid rafts are responsible for the pericanalicular accumulation of InsP3R in hepatocytes, and for the polarized Ca(2+) waves that result. Signaling microdomains exist not only in the plasma membrane, but also in the nearby endoplasmic reticulum, which in turn, helps establish and maintain structural and functional polarity.     

Diagnosis and treatment of a perforated duodenal diverticulum

Perforation is an exceptionally rare complication of duodenal diverticula and often presents with nonspecific symptoms and signs. We present a case of a perforated duodenal diverticulum diagnosed on computed tomography and successfully repaired with a diverticulectomy.     

Synthesis, trafficking, and localization of muscarinic acetylcholine receptors

Muscarinic acetylcholine receptors are members of the G-protein coupled receptor superfamily that are expressed in and regulate the function of neurons, cardiac and smooth muscle, glands, and many other cell types and tissues. The correct trafficking of membrane proteins to the cell surface and their subsequent localization at appropriate sites in polarized cells are required for normal cellular signaling and physiological responses. This review will summarize work on the synthesis and trafficking of muscarinic receptors to the plasma membrane and their localization at the cell surface.     

Physical Women,Emotional Men: Gender and Sexual Satisfaction in Midlife

In late midlife, heterosexual women report markedly lower levels of sexual satisfaction than heterosexual men. This article explored the social factors contributing to this difference, using data from 1,035 sexually-active heterosexual adults, aged 40–59 years, who participated in the National Health and Social Life Survey (NHSLS). Conducted in 1992, NHSLS interviewed a nationally representative random sample of U.S. adults about diverse aspects of sexual life (Laumann et al., 1994, The social organization of sexuality: Sexual practices in the United States. Chicago: University of Chicago Press). Contrary to gender stereotypes, women’s emotional satisfaction was closely associated with bodily sexual practices, whereas men’s physical pleasure was linked to relational factors. Lower levels of sexual satisfaction at older ages appeared to stem from differences between the Baby Boom and older generations rather than from aging per se. Dr. Y. J. Kim is now deceased.     

Ki67 expression levels are a better marker of reduced melanoma growth following MEK inhibitor treatment than phospho-ERK levels

The loss of tumour phospho-extracellular responsive kinase (pERK) positivity is the major treatment biomarker for mitogen-activated protein kinase/extracellular responsive kinase (MEK) inhibitors. Here, we demonstrate that there is a poor correlation between pERK inhibition and the anti-proliferative effects of MEK inhibitors in melanoma cells. We suggest that Ki67 is a better biomarker for future clinical studies.     

Determination of cancer risk associated with germ line BRCA1 missense variants by functional analysis

Germ line inactivating mutations in BRCA1 confer susceptibility for breast and ovarian cancer. However, the relevance of the many missense changes in the gene for which the effect on protein function is unknown remains unclear. Determination of which variants are causally associated with cancer is important for assessment of individual risk. We used a functional assay that measures the transactivation activity of BRCA1 in combination with analysis of protein modeling based on the structure of BRCA1 BRCT domains. In addition, the information generated was interpreted in light of genetic data. We determined the predicted cancer association of 22 BRCA1 variants and verified that the common polymorphism S1613G has no effect on BRCA1 function, even when combined with other rare variants. We estimated the specificity and sensitivity of the assay, and by meta-analysis of 47 variants, we show that variants with <45% of wild-type activity can be classified as deleterious whereas variants with >50% can be classified as neutral. In conclusion, we did functional and structure-based analyses on a large series of BRCA1 missense variants and defined a tentative threshold activity for the classification missense variants. By interpreting the validated functional data in light of additional clinical and structural evidence, we conclude that it is possible to classify all missense variants in the BRCA1 COOH-terminal region. These results bring functional assays for BRCA1 closer to clinical applicability.     

Contact allergy in relation to hand eczema and atopic diseases in north Norwegian schoolchildren

Dotterud LK, Falk ES. Contact allergy in relation to hand eczema and atopic diseases in north Norwegian schoolchildren. Acta Psediatr 1995;84:402–6. Stockholm. ISSN 0803–5253
Patch testing was carried out in 424 schoolchildren (223M, 201F), aged 7–12 years, in northern Norway. In 99 (23.3%) of these children, one or more allergic patch test reactions were demonstrated; 30 children reacted to two and 6 to three or more substances; 53 irritant reactions were recorded in 33 (7.8%) of those tested. From a total of 144 positive tests, the most common allergen was nickel (14.9%), followed by cobalt (5.7%), kathon CG (5.2%), lanolin (1.7%) and neomycin (1.4%). Both allergic and irritant reactions were found twice as frequently in girls as in boys. Positive patch tests were significantly more frequent in atopic (28.8%) than in non–atopic (17.9%) children, being most pronounced in atopic girls (37.4%). Hand eczema was reported to have occurred or to be present in 6.5% of cases. Twenty–nine of 36 children reporting hand eczema participated in the clinical examination. Altogether 15 (3.5%) children had hand eczema at the time of the clinical examination but 12 of these children had no previous history of hand eczema. In 14 of these 15 subjects, the eczema was localized to the back of the hands, with 13 having atopic dermatitis. In 4 of these 15 children, an allergic patch test reaction was found; however, in only 2 of these 4 was the test considered to be clinically relevant for the diagnosis allergic hand eczema. In conclusion, irritant hand eczema may occur in early childhood and is most prevalent in children with atopic dermatitis     

Distinct MHC gene expression patterns during progression of melanoma

Abnormal expression of major histocompatibility complex (MHC) molecules in melanoma has been reported previously. However, the MHC molecule expression patterns in different growth phases of melanoma and the underlying mechanisms are not well understood. Here, we demonstrate that in vertical growth phase (VGP) melanomas, MHC genes are subject to increased rates of DNA copy number gains, accompanied by increased expression, in comparison to normal melanocytes. In contrast, MHC expression in metastatic melanomas drastically decreased compared to VGP melanomas, despite still prevalent DNA copy number gains. Subsequent investigations found that the master transactivator of MHC genes, CIITA, was also significantly downregulated in metastatic melanomas when compared to VGP melanomas. This could be one of the mechanisms accounting for the discrepancy between DNA copy number and expression level in metastatic melanomas, a potentially separate mechanism of gene regulation. These results infer a dynamic role of MHC function in melanoma progression. We propose potential mechanisms for the overexpression of MHC molecules in earlier stages of melanoma as well as for its downregulation in metastatic melanomas. © 2009 Wiley‐Liss, Inc.