Can two wrongs make a right? F508del-CFTR ion channel rescue by second-site mutations in its transmembrane domains

Deletion of phenylalanine 508 (F508del) in the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel is the most common cause of cystic fibrosis (CF). The F508 residue is located on nucleotide-binding domain 1 (NBD1) in contact with the cytosolic extensions of the transmembrane helices, in particular intracellular loop 4 (ICL4). To investigate how absence of F508 at this interface impacts the CFTR protein, we carried out a mutagenesis scan of ICL4 by introducing second-site mutations at eleven positions in cis with F508del. Using an image-based fluorescence assay, we measured how each mutation affected membrane proximity and ion-channel function. The scan strongly validated the effectiveness of R1070W at rescuing F508del defects. Molecular dynamics simulations highlighted two features characterizing the ICL4/NBD1 interface of F508del/R1070W-CFTR: flexibility, with frequent transient formation of interdomain hydrogen bonds, and loosely stacked aromatic sidechains (F1068, R1070W, and F1074, mimicking F1068, F508 and F1074 in wild-type CFTR). F508del-CFTR displayed a distorted aromatic stack, with F1068 displaced towards the space vacated by F508, while, in F508del/R1070F-CFTR, which largely retained F508del defects, R1070F could not form hydrogen bonds and the interface was less flexible. Other ICL4 second-site mutations which partially rescued F508del-CFTR included F1068M and F1074M. Methionine side chains allow hydrophobic interactions without the steric rigidity of aromatic rings, possibly conferring flexibility to accommodate the absence of F508 and retain a dynamic interface. These studies highlight how both hydrophobic interactions and conformational flexibility might be important at the ICL4/NBD1 interface, suggesting possible structural underpinnings of F508del-induced dysfunction

Efficient, non‐toxic anion transport by synthetic carriers in cells and epithelia

Transmembrane anion transporters (anionophores) have potential for new modes of biological activity, including therapeutic applications. In particular they might replace the activity of defective anion channels in conditions such as cystic fibrosis. However, data on the biological effects of anionophores are scarce, and it remains uncertain whether such molecules are fundamentally toxic. Here, we report a biological study of an extensive series of powerful anion carriers. Fifteen anionophores were assayed in single cells by monitoring anion transport in real time through fluorescence emission from halide-sensitive yellow fluorescent protein. A bis-(p-nitrophenyl)ureidodecalin shows especially promising activity, including deliverability, potency and persistence. Electrophysiological tests show strong effects in epithelia, close to those of natural anion channels. Toxicity assays yield negative results in three cell lines, suggesting that promotion of anion transport may not be deleterious to cells. We therefore conclude that synthetic anion carriers are realistic candidates for further investigation as treatments for cystic fibrosis.info:eu-repo/semantics/publishe

Projected Changes to Growth and Mortality of Hawaiian Corals over the Next 100 Years

BACKGROUND: Recent reviews suggest that the warming and acidification of ocean surface waters predicated by most accepted climate projections will lead to mass mortality and declining calcification rates of reef-building corals. This study investigates the use of modeling techniques to quantitatively examine rates of coral cover change due to these effects. METHODOLOGY/PRINCIPAL FINDINGS: Broad-scale probabilities of change in shallow-water scleractinian coral cover in the Hawaiian Archipelago for years 2000-2099 A.D. were calculated assuming a single middle-of-the-road greenhouse gas emissions scenario. These projections were based on ensemble calculations of a growth and mortality model that used sea surface temperature (SST), atmospheric carbon dioxide (CO(2)), observed coral growth (calcification) rates, and observed mortality linked to mass coral bleaching episodes as inputs. SST and CO(2) predictions were derived from the World Climate Research Programme (WCRP) multi-model dataset, statistically downscaled with historical data. CONCLUSIONS/SIGNIFICANCE: The model calculations illustrate a practical approach to systematic evaluation of climate change effects on corals, and also show the effect of uncertainties in current climate predictions and in coral adaptation capabilities on estimated changes in coral cover. Despite these large uncertainties, this analysis quantitatively illustrates that a large decline in coral cover is highly likely in the 21(st) Century, but that there are significant spatial and temporal variances in outcomes, even under a single climate change scenario

Biodegradation of Pig Manure by the Housefly, Musca domestica: A Viable Ecological Strategy for Pig Manure Management

The technology for biodegradation of pig manure by using houseflies in a pilot plant capable of processing 500–700 kg of pig manure per week is described. A single adult cage loaded with 25,000 pupae produced 177.7±32.0 ml of eggs in a 15-day egg-collection period. With an inoculation ratio of 0.4–1.0 ml eggs/kg of manure, the amount of eggs produced by a single cage can suffice for the biodegradation of 178–444 kg of manure. Larval development varied among four different types of pig manure (centrifuged slurry, fresh manure, manure with sawdust, manure without sawdust). Larval survival ranged from 46.9±2.1%, in manure without sawdust, to 76.8±11.9% in centrifuged slurry. Larval development took 6–11 days, depending on the manure type. Processing of 1 kg of wet manure produced 43.9–74.3 g of housefly pupae and the weight of the residue after biodegradation decreased to 0.18–0.65 kg, with marked differences among manure types. Recommendations for the operation of industrial-scale biodegradation facilities are presented and discussed

Three monthly coral Sr/Ca records from the Chagos Archipelago covering the period of 1950-1995 A.D.: reproducibility and implications for quantitative reconstructions of sea surface temperature variations

In order to assess the fidelity of coral Sr/Ca for quantitative reconstructions of sea surface temperature variations, we have generated three monthly Sr/Ca time series from Porites corals from the lagoon of Peros Banhos (71°E, 5°S, Chagos Archipelago). We find that all three coral Sr/Ca time series are well correlated with instrumental records of sea surface temperature (SST) and air temperature. However, the intrinsic variance of the single-core Sr/Ca time series differs from core to core, limiting their use for quantitative estimates of past temperature variations. Averaging the single-core data improves the correlation with instrumental temperature (r > 0.7) and allows accurate estimates of interannual temperature variations (~0.35°C or better). All Sr/Ca time series indicate a shift towards warmer temperatures in the mid-1970s, which coincides with the most recent regime shift in the Pacific Ocean. However, the magnitude of the warming inferred from coral Sr/Ca differs from core to core and ranges from 0.26 to 0.75°C. The composite Sr/Ca record from Peros Banhos clearly captures the major climatic signals in the Indo-Pacific Ocean, i.e. the El Niño–southern oscillation and the Pacific decadal oscillation. Moreover, composite Sr/Ca is highly correlated with tropical mean temperatures (r = 0.7), suggesting that coral Sr/Ca time series from the tropical Indian Ocean will contribute to multi-proxy reconstructions of tropical mean temperatures

The quality of life of patients with genital warts: a qualitative study

<p>Abstract</p> <p>Background</p> <p>Genital warts, which are caused by infection with human papillomavirus (HPV), are one of the most common sexually transmitted diseases in Europe. Although genital warts are commonly perceived as a non-serious condition, treatment is often long, of varying effectiveness and the recurrence rate is high. Very few studies have been performed on the personal consequences of genital warts. The aim of this qualitative study, set in Denmark, was to examine the ways in which genital warts may affect patients' quality of life.</p> <p>Methods</p> <p>To obtain an in-depth understanding of patients' perceptions of genital warts, we used qualitative focus-group interviews with five men and five women aged between 18 and 30 years who had genital warts. The interview guide was based on a literature review that identified important issues and questions. The data were analysed using a medical anthropological approach.</p> <p>Results</p> <p>Patients' experiences were related to cultural conceptions of venereal diseases and the respective identities and sexuality of the sexes. The disease had negative psychological and social effects both for men and for women and it affected their sex and love lives, in particular. The psychological burden of the disease was increased by the uncertain timeline and the varying effectiveness of treatment. We identified a need for more patient information about the disease and its psycho-sexual aspects.</p> <p>Conclusions</p> <p>The men and women participating in this study considered their quality of life to be significantly lowered because of genital warts. The experiences described by the participants give insights that may be valuable in treatment and counselling.</p> <p>The quadrivalent HPV vaccine that has now been added to the childhood vaccination programme for girls in Denmark for the prevention of cervical cancer can also prevent 90% of cases of genital warts. Our results suggest that HPV vaccination could considerably reduce the largely unacknowledged psychological and social burden associated with genital warts, in men as well as women.</p

Strategies to prevent intraoperative lung injury during cardiopulmonary bypass

During open heart surgery the influence of a series of factors such as cardiopulmonary bypass (CPB), hypothermia, operation and anaesthesia, as well as medication and transfusion can cause a diffuse trauma in the lungs. This injury leads mostly to a postoperative interstitial pulmonary oedema and abnormal gas exchange. Substantial improvements in all of the above mentioned factors may lead to a better lung function postoperatively. By avoiding CPB, reducing its time, or by minimizing the extracorporeal surface area with the use of miniaturized circuits of CPB, beneficial effects on lung function are reported. In addition, replacement of circuit surface with biocompatible surfaces like heparin-coated, and material-independent sources of blood activation, a better postoperative lung function is observed. Meticulous myocardial protection by using hypothermia and cardioplegia methods during ischemia and reperfusion remain one of the cornerstones of postoperative lung function. The partial restoration of pulmonary artery perfusion during CPB possibly contributes to prevent pulmonary ischemia and lung dysfunction. Using medication such as corticosteroids and aprotinin, which protect the lungs during CPB, and leukocyte depletion filters for operations expected to exceed 90 minutes in CPB-time appear to be protective against the toxic impact of CPB in the lungs. The newer methods of ultrafiltration used to scavenge pro-inflammatory factors seem to be protective for the lung function. In a similar way, reducing the use of cardiotomy suction device, as well as the contact-time between free blood and pericardium, it is expected that the postoperative lung function will be improved

Regulation of ABCC6 trafficking and stability by a conserved C-terminal PDZ-like sequence

Mutations in the ABCC6 ABC-transporter are causative of pseudoxanthoma elasticum (PXE). The loss of functional ABCC6 protein in the basolateral membrane of the kidney and liver is putatively associated with altered secretion of a circulatory factor. As a result, systemic changes in elastic tissues are caused by progressive mineralization and degradation of elastic fibers. Premature arteriosclerosis, loss of skin and vascular tone, and a progressive loss of vision result from this ectopic mineralization. However, the identity of the circulatory factor and the specific role of ABCC6 in disease pathophysiology are not known. Though recessive loss-of-function alleles are associated with alterations in ABCC6 expression and function, the molecular pathologies associated with the majority of PXE-causing mutations are also not known. Sequence analysis of orthologous ABCC6 proteins indicates the C-terminal sequences are highly conserved and share high similarity to the PDZ sequences found in other ABCC subfamily members. Genetic testing of PXE patients suggests that at least one disease-causing mutation is located in a PDZ-like sequence at the extreme C-terminus of the ABCC6 protein. To evaluate the role of this C-terminal sequence in the biosynthesis and trafficking of ABCC6, a series of mutations were utilized to probe changes in ABCC6 biosynthesis, membrane stability and turnover. Removal of this PDZ-like sequence resulted in decreased steady-state ABCC6 levels, decreased cell surface expression and stability, and mislocalization of the ABCC6 protein in polarized cells. These data suggest that the conserved, PDZ-like sequence promotes the proper biosynthesis and trafficking of the ABCC6 protein. © 2014 Xue et al