Demonstration of a functional apical sodium hydrogen exchanger in isolated rat gastric glands

Previous studies have shown that gastric glands express at least sodium-hydrogen exchanger (NHE) isoforms 1-4. Our aim was to study NHE-3 localization in rat parietal cells and to investigate the functional activity of an apical membrane NHE-3 isoform in parietal cells of rats. Western blot analysis and immunohistochemistry showed expression of NHE-3 in rat stomach colocalizing the protein in parietal cells together with the beta-subunit of the H(+)-K(+)-ATPase. Functional studies in luminally perfused gastric glands demonstrated the presence of an apical NHE isoform sensitive to low concentrations of 5-ethylisopropyl amiloride (EIPA). Intracellular pH measurements in parietal cells conducted in omeprazole-pretreated superfused gastric glands showed an Na+-dependent proton extrusion pathway that was inhibited both by low concentrations of EIPA and by the NHE-3 specific inhibitor S3226. This pathway for proton extrusion had a higher activity in resting glands and was inhibited on stimulation of histamine-induced H(+)-K(+)-ATPase proton extrusion. We conclude that the NHE-3 isoform located on the apical membrane of parietal cells offers an additional pathway for proton secretion under resting conditions. Furthermore, the gastric NHE-3 appears to work under resting conditions and inactivates during periods of H(+)-K(+)-ATPase activity.     

Long-term platinum retention after treatment with cisplatin and oxaliplatin

Background  

The aim of this study was to evaluate long-term platinum retention in patients treated with cisplatin and oxaliplatin.     

Reliability and Validity of an Interviewer-Administered Adaptation of the Youth Self-Report for Mental Health Screening of Vulnerable Young People in Ethiopia

Objective

Evaluate the reliability and validity of the Youth Self-Report (YSR) as a screening tool for mental health problems among young people vulnerable to HIV in Ethiopia.

Design

A cross-sectional assessment of young people currently receiving social services.

Methods

Young people age 15–18 participated in a study where a translated and adapted version of the YSR was administered by trained nurses, followed by an assessment by Ethiopian psychiatrists. Internal reliability of YSR syndrome scales were assessed using Chronbach''s alpha. Test-retest reliability was assessed through repeating the YSR one month later. To assess validity, analysis of the sensitivity and specificity of the YSR compared to the psychiatrist assessment was conducted.

Results

Across the eight syndrome scales, the YSR best measured the diagnosis of anxiety/depression and social problems among young women, and attention problems among young men. Among individual YSR syndrome scales, internal reliability ranged from unacceptable (Chronback’s alpha = 0.11, rule-breaking behavior among young women) to good (α≥0.71, anxiety/depression among young women). Anxiety/depression scores of ≥8.5 among young women also had good sensitivity (0.833) and specificity (0.754) to predict a true diagnosis. The YSR syndrome scales for social problems among young women and attention problems among young men also had fair consistency and validity measurements. Most YSR scores had significant positive correlations between baseline and post-one month administration. Measures of reliability and validity for most other YSR syndrome scales were fair to poor.

Conclusions

The adapted, personally administered, Amharic version of the YSR has sufficient reliability and validity in identifying young vulnerable women with anxiety/depression and/or social problems, and young men with attention problems; which were the most common mental health disorders observed by psychiatrists among the migrant populations in this study. Further assessment of the applicability of the YSR among vulnerable young people for less common disorders in Ethiopia is needed.     

Hypertonic Saline Attenuates Colonic Tumor Cell Metastatic Potential by Activating Transmembrane Sodium Conductance

Hypertonic saline (HTS) suppresses tumor cell-endothelial interactions by reducing integrin expression. This translates into reduced adhesion, migration and metastatic potential. This study determined the relative contributions of hyperosmolarity and sodium-specific hypertonicity on the inhibitory effects of HTS, the intracellular pH and sodium responses to HTS and the role of cytoskeletal remodeling in these changes. Human colonic tumor cells (LS174T) were exposed to lipopolysaccharide under isotonic, hypertonic, sodium-free (N-methyl- D-glucamine), hyperosmolar (mannitol or urea), disrupted cytoskeletal (10 μg/ml cytochalasin D) conditions or in the presence of 5-(N-ethyl-N-isopropyl)amiloride (EIPA). β₁ integrin expression was measured flow-cytometrically. Intracellular sodium and pH were measured with confocal laser microscopic imaging. Statistical analysis was performed with analysis of variance, and P < 0.05 was considered significant. Data are represented as mean ± SEM. Hypertonic exposure attenuated integrin expression (62.03 ± 4.7% of control, P < 0.04). No discernible effect was observed with sodium-free or hyperosmolar solutions. HTS evoked a cellular alkalinization (by a mean 0.2 pH units) and an increase in cytosolic sodium concentration (by a mean 12.4 mM, P < 0.001) via upregulation of sodium-hydrogen exchange. Disassembly of actin microfilaments by cytochalasin D and antiporter inhibition with EIPA abrogated the effect of hypertonicity on integrin expression and intracellular sodium and pH (P < 0.05). HTS downregulates adhesion molecule expression via a hypertonic, sodium-specific, cytoskeletally mediated mechanism that involves activation of sodium-hydrogen exchange with associated changes in intracellular pH and sodium concentrations.     

Quantitative and qualitative differences in morphological traits revealed between diploid Fragaria species

BACKGROUND AND AIMS: The aims of this investigation were to highlight the qualitative and quantitative diversity apparent between nine diploid Fragaria species and produce interspecific populations segregating for a large number of morphological characters suitable for quantitative trait loci analysis. METHODS: A qualitative comparison of eight described diploid Fragaria species was performed and measurements were taken of 23 morphological traits from 19 accessions including eight described species and one previously undescribed species. A principal components analysis was performed on 14 mathematically unrelated traits from these accessions, which partitioned the species accessions into distinct morphological groups. Interspecific crosses were performed with accessions of species that displayed significant quantitative divergence and, from these, populations that should segregate for a range of quantitative traits were raised. KEY RESULTS: Significant differences between species were observed for all 23 morphological traits quantified and three distinct groups of species accessions were observed after the principal components analysis. Interspecific crosses were performed between these groups, and F2 and backcross populations were raised that should segregate for a range of morphological characters. In addition, the study highlighted a number of distinctive morphological characters in many of the species studied. CONCLUSIONS: Diploid Fragaria species are morphologically diverse, yet remain highly interfertile, making the group an ideal model for the study of the genetic basis of phenotypic differences between species through map-based investigation using quantitative trait loci. The segregating interspecific populations raised will be ideal for such investigations and could also provide insights into the nature and extent of genome evolution within this group.     

Inhibition of NHE-1 Na+/H+ exchanger by natriuretic peptides in ocular nonpigmented ciliary epithelium

The natriuretic peptides (NPs) atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) display hypotensive effects in the mammalian eye by lowering the intraocular pressure (IOP), a function that is mediated by the bilayer ocular ciliary epithelium (CE), in conjunction with the trabecular meshwork. ANP regulates Na⁺/H⁺ exchanger (NHE) activity, and inhibitors of NHE have been shown to lower IOP. We examined whether NPs influence the NHE activity of the CE, which is comprised of pigmented (PE) and nonpigmented (NPE) epithelial cells, by directly recording the rate of intracellular pH (pH_i) recovery from its inner NPE cell layer. NPs inhibited, in a dose-dependent manner (1–100 nM), the rate of pH_i recovery with the order of potency CNP > ANP > BNP, indicative that this inhibition is mediated by the presence of NPR type B receptors. 8-Bromo-cGMP (8-BrcGMP), a nonhydrolyzable analog of cGMP, mimicked NPs in inhibiting the rate of Na⁺-dependent pH_i recovery. In contrast, ethylisopropyl amiloride (EIPA, 100 nM) or amiloride (10 µM) completely abolished the pH_i recovery by NHE. 18-Glycyrrhetinic acid (18-GA), a gap junction blocker, attenuated the inhibitory effect of CNP on the rate of pH_i recovery, suggesting that NHE activity in both cell layers of the CE is coregulated. This interpretation was supported, in part, by the coexpression of NHE-1 isoform mRNA in both NPE and PE cells. The mechanism by which the inhibitory effect of NPs on NHE-1 activity might influence the net solute movement or fluid transport by the bilayer CE remains to be determined. Na⁺/H⁺ exchanger type 1; intracellular pH; aqueous humor     

Development of enzyme-immunoassays based on egg yolk antibodies for the detection of mycotoxins

Enzyme-linked immunosorbent assays (ELISA) proved to be a fast and simple method for the detection of mycotoxins and other undesired contaminants in food and feed. The present study is focused on the optimisation and exploitation of the egg yolk antibody technology in order to develop competitive ELISAs for the detection of mycotoxins in cereals. Due to its importance as one of the most relevant Fusarium mycotoxins, the trichothecene deoxynivalenol (DON) was selected as representative. Chickens were immunised with different protein conjugates performing varying booster intervals. The antibodies were isolated by the poly(ethylene glycol) precipitation method according to Polson. By use of these antibodies an indirect competitive ELISA was developed for the detection of DON. First investigations of naturally contaminated wheat samples showed a good correspondence with results obtained by GC-ECD when calibration in blank wheat extracts was performed.