There is growing evidence that the amyloid beta-peptide (beta 1-40) is involved in the aetiology of Alzheimer's disease also implicating an altered calcium homeostasis of affected cells. Beta 1-40 has been proposed to form calcium channels in synthetic bilayer membranes [1]. We wanted to investigate in the present study whether beta 1-40 (or fragments thereof) could act as ionophores in a biological membrane like the one in human erythrocytes. Incubation of the cells for 2 h and 4 h at 37 degrees C together with 6 mumol L-1 of beta 1-40 or of fragments beta 1-28 and beta 25-35, resulted in a significantly decreased energy charge qualitatively similar to the one obtained by a known calcium ionophore (A 23187, 0.05 mumol L-1). Moreover, beta 1-40 and its two fragments induced a significant alteration of 45Ca permeability in human red blood cells of the same type as the one achieved by the calcium ionophore. The ionophoric action of beta 1-40 and its two fragments may lead to an increase of the intracellular calcium ion concentration, in turn resulting in enhanced Ca(2+)-ATPase activity and a decrease in energy charge. This may be valid also for neuronal plasma membranes and could, therefore, be a possible aetiological mechanism in Alzheimer's disease.

A simplified enzymatic method for determination of serum 3 alpha-hydroxy bile acids (3 alpha-HBA) has been evaluated. Analytical precision was low in the normal range but satisfactory for elevated values. The fasting upper reference value was 8.0 mumol/l. In 12 healthy subjects serum 3 alpha-HBA levels were measured after oral loads (125, 250, 500, and 1000 mg) of unconjugated chenodeoxycholic acid (CDA). After the 125-mg CDA loading dose no significant increase in serum 3 alpha-HBA was observed, but with the 250 mg CDA loading dose serum 3 alpha-HBA levels were elevated at 30, 60, and 120 min. The loading doses of 500 mg and 1000 mg CDA produced significant increases in serum 3 alpha-HBA levels throughout the observation period (3 h). When sera with increased serum bile acids were analyzed by radioimmunoassay for CDA, the results correlated well with those obtained enzymatically. The usefulness of the simplified method is evident in this situation, and we also find it useful for serum bile acid determination after an oral bile acid loading test with CDA. The method is easy to perform and requires only standard laboratory equipment.

The data indicate a direct role of insulin in the transport process of calcium into normal human erythrocytes.

The pathophysiological link between adiposity and blood pressure is not completely understood, and evidence suggests an influence of sex and genetic determinants. We aimed to identify the relationship between adiposity and blood pressure, independent of a robust set of lifestyle and metabolic factors, and to examine the modulating role of sex and Angiotensin-Converting Enzyme (ACE) insertion/deletion (I/D) polymorphisms. In the Relationship Between Insulin Sensitivity and Cardiovascular Disease (RISC) study cohort, 1211 normotensive individuals, aged 30 to 60 years and followed-up after 3.3 years, were characterized for lifestyle and metabolic factors, body composition, and ACE genotype. Body mass index (BMI) and waist circumference (WC) were independently associated with mean arterial pressure, with a stronger relationship in women than men (BMI: r =0.40 versus 0.30; WC: r =0.40 versus 0.30, both P <0.01) and in individuals with the ID and II ACE genotypes in both sexes ( P <0.01). The associations of BMI and WC with mean arterial pressure were independent of age, sex, lifestyle, and metabolic variables (standardized regression coefficient=0.17 and 0.18 for BMI and WC, respectively) and showed a significant interaction with the ACE genotype only in women ( P =0.03). A 5 cm larger WC at baseline increased the risk of developing hypertension at follow-up only in women (odds ratio, 1.56 [95% CI, 1.15–2.10], P =0.004) and in II genotype carriers (odds ratio, 1.87 [95% CI, 1.09–3.20], P =0.023). The hypertensive effect of adiposity is more pronounced in women and in people carrying the II variant of the ACE genotype, a marker of salt sensitivity.

Recent epidemiological studies highlight the strong association between high body mass index (BMI) and enhanced risk of colon cancer. This association appears stronger in men than in women, indicating a possible protective role of estrogens in this context. The biological action of the estrogens is mediated by specific transcription factors, the estrogen receptors (ERs). ERβ is the main ER in the intestine; and it is expressed in both epithelial cells and immune cells. Anti-inflammatory and anti-tumorigenic effects of ERβ in colitis-associated neoplasia have been demonstrated. Several rodent models for obesity show an impaired intestinal epithelial barrier function and an increase of pro-inflammatory markers in the colon. Moreover, in murine colitis models, high fat diet (HFD) exacerbates colonic inflammation. However, the specific molecular mechanisms linking obesity to increased colon cancer development, where estrogen signaling may be involved, is not clear. We hypothesize that ERβ-selective agonists can oppose the HFD-mediated inflammatory pro-tumorigenic colonic signalling in a gender-specific manner during obesity, and thereby protect against colorectal cancer. Our study is focused on the initiation of colon inflammation during obesity and aims to investigate the impact of ERβ activation in this context. To address this question, male and female mice were fed a HFD for 26 weeks and treated with a ERβ-selective agonist for 3 weeks prior sacrifice. Stool pellets were regularly collected. Animals were sacrificed; colon samples and caecal contents were collected for further analysis. We show that the expression pattern of inflammatory genes in colon is modified by the ERβ-selective agonist in HFD fed mice. Moreover the ERβ-selective agonist appears to induce gender-specific changes of the microbiota of HFD-fed mice. Our results show that an ERβ-selective agonist can modulate the colon microenvironment during obesity in mice and will provide a better comprehension of the molecular mechanisms leading to obesity-associated colonic inflammation. Citation Format: Amena Archer, Linnea Pettersson, Marcela González-Granillo, Christina Savva, Marion Korach-André, Cecilia Williams. Role of estrogen signaling in colon microenvironment during obesity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4401. doi:10.1158/1538-7445.AM2017-4401