Basolateral ClC-2 chloride channels in surface colon epithelium: regulation by a direct effect of intracellular chloride

BACKGROUND & AIMS: The principal function of the colon in fluid homeostasis is the absorption of NaCl and water. Apical membrane Na(+) channels, Na(+)/H(+), and Cl(-)/HCO(3)(-) exchangers have been postulated to mediate NaCl entry into colonocytes. The basolateral exit pathway for Cl(-) has recently been proposed to be via ClC-2 channels present in that membrane domain in surface epithelium. The aim of this report is to obtain functional data for a basolateral localization of ClC-2 and explore a possible direct regulation by intracellular Cl(-). METHODS: Guinea pig colon epithelium with the apical membrane perforated with nystatin in Ussing chambers is used to show a basolateral Cl(-) conductance. Gramicidin D perforated-patch configuration of the patch-clamp technique is used on isolated surface colonocytes. Heterologous expression of the recombinant channel and the whole-cell configuration are used to investigate a direct regulation by intracellular Cl(-). RESULTS: A basolateral membrane conductance with the characteristics of ClC-2 channels, including Cd(2+) sensitivity, selectivity, and inhibition by extracellular alkalinization, is present in distal colon epithelium. The effect of intracellular Cl(-) on this conductance suggests activation by the permeant anion. Using the recombinant ClC-2 channel, a strong dependence of its activity on intracellular Cl(-) is shown, with a shift of activation to more positive voltages as [Cl(-)](i) is increased. CONCLUSIONS: It is suggested that ClC-2 serves as an exit pathway for Cl(-) in the basolateral membranes of the distal colon and that its dependence on [Cl(-)](i) might provide a cross-talk mechanism to match fluxes at the apical and basolateral domains of these epithelial cells.     

Complicaciones infecciosas en niños tratados con oxigenación por membrana extracorpórea

Introduction

The aim of this study was to analyse the incidence, treatment and evolution of infections in children treated with ECMO.

Films based on the biopolymer poly(3-hydroxybutyrate) as platforms for the controlled release of dexamethasone

Controlled drug delivery aims to achieve an effective drug concentration in the action site for a desired period of time, while minimizing side effects. In this contribution, biodegradable poly(3-hydroxybutyrate) films were evaluated as a reservoir platform for dexamethasone controlled release. These systems were morphological and physicochemically characterized. In vitro release assays were performed for five different percentages of drug in the films and data were fitted by a mathematical model developed and validated by our research group. When the profiles were normalized, a single curve properly fitted all the experimental data. Using this unique curve, the dissolution efficiency (DE), the time to release a given amount of drug (t_X%), and the mean dissolution time were calculated. Furthermore, the dissolution rate, the initial dissolution rate (a%) and the intrinsic dissolution rate were determined. The a% mean value was 1.968 × 10^?2% released/min, t_80% was about 14 days, and the DE was 59.6% at 14 days and 66.5% at 20 days. After 2 days, when approximately 40% of the drug was released, the dissolution rate decreased about 60% respect to the initial value. The poly(3-hydroxybutyrate) platforms behaved as an appropriate system to release and control the dexamethasone delivery, suggesting that they could be an alternative to improve drug therapy.     

Assessment of Bone Microarchitecture in Postmenopausal Women on Long‐Term Bisphosphonate Therapy With Atypical Fractures of the Femur

Reports of atypical femoral fractures (AFFs) in patients receiving long‐ term bisphosphonate therapy have raised concerns regarding the genesis of this rare event. Using high‐resolution peripheral quantitative computed tomography (HR‐pQCT), we conducted a study to evaluate bone microarchitecture in patients who had suffered an AFF during long‐term bisphosphonate treatment. The aim of our study was to evaluate if bone microarchitecture assessment could help explain the pathophysiology of these fractures. We compared bone volumetric density and microarchitectural parameters measured by HR‐pQCT in the radius and tibia in 20 patients with AFFs with 35 postmenopausal women who had also received long‐term bisphosphonate treatment but had not experienced AFFs, and with 54 treatment‐naive postmenopausal women. Control groups were similar in age, body mass index (BMI), and bone mineral density (BMD). Mean age of the 20 patients with AFFs was 71 years, mean lumbar spine T‐score was ?2.2, and mean femoral neck T‐score was ?2. Mean time on bisphosphonate treatment was 10.9 years (range, 5–20 years). None of the patients had other conditions associated with AFFs such as rheumatoid arthritis, diabetes or glucocorticoid use. There were no statistically significant differences in any of the parameters measured by HR‐pQCT between postmenopausal women with or without treatment history and with or without history of atypical fractures. We could not find any distinctive microarchitecture features in the peripheral skeleton of women who had suffered an atypical fracture of the femur while receiving bisphosphonate treatment. This suggests that risk of developing an atypical fracture is not related to bone microarchitecture deterioration. Our results indicate that there may be other individual factors predisposing to atypical fractures in patients treated with bisphosphonates, and that those are independent of bone microarchitecture. In the future, identification of those factors could help prevent and understand the complex physiopathology of these rare events. © 2014 American Society for Bone and Mineral Research.     

Exploration of clients living with HIV needs for reporting on experiences with sex

Talking about sex with people living with HIV receives insufficient attention in health care. A cross‐sectional and exploratory study describes the preferences of people living with HIV to talk about sex with specialized HIV physicians and nurses in a clinic in Barcelona (Spain). A 27‐item self‐administered questionnaire was used between June 2017 and May 2018. One hundred fourteen people agreed to participate. Data were analyzed using multivariate logistic regression. Most of the participants reported “never or almost never” having been asked about sex practices in visits with the HIV specialist physician (n = 65 [57.0%]) or nurse (n = 74 [64.9%]). Older participants stated that neither physicians nor nurses talked about sex during visits. Women felt that physicians hardly ever asked about their sexual practices. Men who had sex with other men indicated that their physicians always asked about their sex practices compared with heterosexuals living with HIV. Health professionals should reformulate how to talk about sex with people living with HIV to facilitate communication and provide adequate care.     

Colonic Microbiota Profile Characterization of the Responsiveness to Dietary Fibre Treatment in Hypercholesterolemia

This study aimed to determine how the microbiota profile might be predisposed to a better response in blood lipid profiles due to dietary fibre supplementation. A three-arm intervention study that included three different fibre types (mainly insoluble, soluble, and antioxidant fibre) supplemented (19.2 g/day) during 2 months in individuals with hypercholesterolemia was developed. Changes in faecal microbiota and blood lipid profile after fibre supplementation were determined. In all volunteers, regardless of fibre type, an increase in the abundance of Bifidobacterium was observed, and similarly, an inverse relationship between faecal propionic acid and blood LDL-cholesterol, LDL particle size, and LDL/HDL particle ratio (p-values 0.0067, 0.0002, and 0.0067, respectively) was observed. However, not all volunteers presented an improvement in lipid profile. The non-responders to fibre treatment showed a decrease in microbiota diversity (Shannon and Simpson diversity index p-values of 0.0110 and 0.0255, respectively) after the intervention; where the reduction in short-chain fatty acids (SCFAs) producing bacterial genera such as Clostridium XIVa and Ruminococcus after dietary fibre treatment was the main difference. It was concluded that the non-responsiveness to dietary fibre treatment might be mediated by the lack of ability to maintain a stable SCFA producing bacteria diversity and composition after extra fibre intake.     

Gabapentin for uremic pruritus: a systematic review of randomized controlled trials

Uremic pruritus is one of the most prevalent and bothersome dermatologic symptoms in patients with end-stage renal disease. Some studies suggest a possible neuropathic cause of uremic pruritus. Gabapentin, an anticonvulsant, may control pruritus with neuropathic origin. The objectives of this study were to assess the efficacy of gabapentin in reducing pruritus scores of patients with uremic pruritus and evaluate its safety among dialysis patients. Meta-analysis of randomized controlled trials, using gabapentin as treatment for uremic pruritus among hemodialysis patients was included and analyzed using Review Manager Version 5.1.4 software. Seven out of 17 screened articles were included, with a total of 315 participants. Meta-analysis of the incidence of improved pruritus scores after treatment from four studies (n = 171) showed that treatment with gabapentin decreased the severity of uremic pruritus as compared to the placebo (risk ratio = 0.18; 95% confidence interval: 0.09, 0.33; I² = 4%: P =< 0.00001). Six studies (n = 290) presented with incidence of adverse drug events such as dizziness, drowsiness, and somnolence. In the pooled analysis, treatment with gabapentin was associated with a higher incidence of adverse drug events compared to the comparator drugs, but the results were not significant (risk ratio = 1.3, 95% confidence interval: 0.81, 2.11; P = 0.28, I² = 37%). The results of this systematic review suggest that gabapentin is efficacious and safe in improving uremic pruritus among dialysis patients.