Functional reconstitution of SdcS, a Na+-coupled dicarboxylate carrier protein from Staphylococcus aureus

In Staphylococcus aureus, the transport of dicarboxylates is mediated in part by the Na+-linked carrier protein SdcS. This transporter is a member of the divalent-anion/Na+ symporter (DASS) family, a group that includes the mammalian Na+/dicarboxylate cotransporters NaDC1 and NaDC3. In earlier work, we cloned and expressed SdcS in Escherichia coli and found it to have transport properties similar to those of its eukaryotic counterparts (J. A. Hall and A. M. Pajor, J. Bacteriol. 187:5189-5194, 2005). Here, we report the partial purification and subsequent reconstitution of functional SdcS into liposomes. These proteoliposomes exhibited succinate counterflow activity, as well as Na+ electrochemical-gradient-driven transport. Examination of substrate specificity indicated that the minimal requirement necessary for transport was a four-carbon terminal dicarboxylate backbone and that productive substrate-transporter interaction was sensitive to substitutions at the substrate C-2 and C-3 positions. Further analysis established that SdcS facilitates an electroneutral symport reaction having a 2:1 cation/dicarboxylate ratio. This study represents the first characterization of a reconstituted Na+-coupled DASS family member, thus providing an effective method to evaluate functional, as well as structural, aspects of DASS transporters in a system free of the complexities and constraints associated with native membrane environments.     

Are Binary Copper Sulfides/Selenides Really New and Promising Thermoelectric Materials?

Copper sulfides and copper selenides have recently been reported as new and promising low‐cost and environmentally friendly thermoelectric materials. Here, it is shown that these materials have actually been studied for more than 190 years and the absence of commercial thermoelectric modules based on them stems from some major intrinsic issues related to these chalcogenides. Further development of these semiconductors will require addressing and solving these problems before large scale utilization can be considered.     

Tissue engineering: revolution and challenge in auricular cartilage reconstruction

External ear reconstruction for congenital deformity such as microtia or following trauma remains one of the greatest challenges for reconstructive plastic surgeons. The problems faced in reconstructing the intricate ear framework are highly complex. A durable, inert material that is resistant to scar contracture is required. To date, no material, autologous or prosthetic, is available that perfectly mimics the shapely elastic cartilage found in the ear. Current procedure involves autologous costal cartilage that is sculpted to create a framework for the overlying soft tissues. However, this is associated with donor-site morbidity, and few surgeons worldwide are skilled in the techniques required to obtain excellent results. Various alloplastic materials have therefore been used as a framework. However, a degree of immunogenicity and infection and extrusion are inevitable, and results are often disappointing. Tissue-engineered cartilage is an alternative approach but, despite significant progress in this area, many problems remain. These need to be addressed before routine clinical application will become possible. The current tissue-engineered options are fragile and inflexible. The next generation of auricular cartilage engineering is promising, with smart materials to enhance cell growth and integration, and the application of stem cells in a clinical setting. More recently, the authors' team designed the world's first entirely synthetic trachea composed of a novel nanocomposite material seeded with the patient's own stem cells. This was successfully transplanted in a patient at the Karolinska Hospital in Sweden and may translate into a tissue-engineered auricle in the future.     

Heat or insulation: behavioral titration of mouse preference for warmth or access to a nest

In laboratories, mice are housed at 20–24°C, which is below their lower critical temperature (≈30°C). This increased thermal stress has the potential to alter scientific outcomes. Nesting material should allow for improved behavioral thermoregulation and thus alleviate this thermal stress. Nesting behavior should change with temperature and material, and the choice between nesting or thermotaxis (movement in response to temperature) should also depend on the balance of these factors, such that mice titrate nesting material against temperature. Naïve CD-1, BALB/c, and C57BL/6 mice (36 male and 36 female/strain in groups of 3) were housed in a set of 2 connected cages, each maintained at a different temperature using a water bath. One cage in each set was 20°C (Nesting cage; NC) while the other was one of 6 temperatures (Temperature cage; TC: 20, 23, 26, 29, 32, or 35°C). The NC contained one of 6 nesting provisions (0, 2, 4, 6, 8, or 10g), changed daily. Food intake and nest scores were measured in both cages. As the difference in temperature between paired cages increased, feed consumption in NC increased. Nesting provision altered differences in nest scores between the 2 paired temperatures. Nest scores in NC increased with increasing provision. In addition, temperature pairings altered the difference in nest scores with the smallest difference between locations at 26°C and 29°C. Mice transferred material from NC to TC but the likelihood of transfer decreased with increasing provision. Overall, mice of different strains and sexes prefer temperatures between 26–29°C and the shift from thermotaxis to nest building is seen between 6 and 10 g of material. Our results suggest that under normal laboratory temperatures, mice should be provided with no less than 6 grams of nesting material, but up to 10 grams may be needed to alleviate thermal distress under typical temperatures.     

Prognostic significance of nuclear and cytoplasmic expression of metallothioneins as related to proliferative activity in squamous cell carcinomas of oral cavity

Metallothioneins (MT) are low molecular weight proteins with high metal and cystein contents. This study was designed to test the hypothesis that cytoplasmic and nuclear MT expression are of prognostic importance in patients with squamous cell carcinomas of the oral cavity, treated by surgery with subsequent radiotherapy. The second aim of the study was to test the potential correlation between the nuclear and cytoplasmic MT expressions as compared to expression of proliferation markers and other clinicopathological variables. Material and Methods: The studies were performed on tumor samples from 50 patients with diagnosis of squamous cell carcinoma of the oral cavity floor or of oral part of the tongue. All the patients were subjected to radical surgery, accompanied by removal of lymph nodes and post-operative radiotherapy. Results: No significant correlation could be detected between percentage and intensity of MT expression on one hand and proportions of cells with Mcm-2 (minichromosome maintenance protein 2), Ki-67 expressions, nor the grade of malignancy (G) on the other. A significantly shorter survival was detected among patients with tumors of MT expression rated 9 or 12 according to the Remmele scale and among patients with a high percentage (> 50%) of nuclear MT staining. In mulivariate analyses, only OTT (Overall Treatment Time), lymph node involvement and high expression of Mcm-2 were found to be independent risk factors for decreased patient's survival. Conclusion: This is relevant evidence that MT overexpression could be related to worse prognosis in patients with oral cancer. We have found no relationship between MT expression and proliferative activity.     

In vitro fertilisation with recombinant follicle stimulating hormone requires less IU usage compared with highly purified human menopausal gonadotrophin: results from a European retrospective observational chart review

Background  

Previous studies have reported conflicting results for the comparative doses of recombinant follicle stimulating hormone (rFSH) and highly purified human menopausal gonadotrophin (hMG-HP) required per cycle of in vitro fertilisation (IVF); the aim of this study was to determine the average total usage of rFSH versus hMG-HP in a 'real-world' setting using routine clinical practice.     

Angiotensin converting enzyme gene polymorphism is associated with severity of coronary artery disease in men with high total cholesterol levels

This study examines whether renin-angiotensin-aldosterone system gene polymorphisms: ACE (encoding for angiotensin converting enzyme) c.2306-117_404 I/D, AGTR1 (encoding for angiotensin II type-1 receptor) c.1080*86A>C and CYP11B2 (encoding for aldosterone synthase) c.-344C>T are associated with the extension of coronary atherosclerosis in a group of 647 patients who underwent elective coronary angiography. The extension of CAD was evaluated using the Gensini score. The polymorphisms were determined by PCR and RFLP assays. The associations between genotypes and the extent of coronary atherosclerosis were tested by the Kruskal-Wallis test, followed by pairwise comparisons using Wilcoxon test. The population has been divided into groups defined by: sex, smoking habit, past myocardial infarction, BMI (>, ≤ 25), age (>, ≤ 55), diabetes mellitus, level of total cholesterol (>, ≤ 200 mg/dl), LDL cholesterol (>, ≤ 130 mg/dl), HDL cholesterol (>, ≤ 40 mg/dl), triglycerides (>, ≤ 150 mg/dl). Significant associations between the ACE c.2306-117_404 I/D polymorphism and the Gensini score in men with high total cholesterol levels (P_{Kruskal-Wallis} = 0.008; P_adjusted = 0.009), high level of LDL cholesterol (P_{Kruskal-Wallis} = 0.016; P_adjusted = 0.028) and low level of HDL cholesterol (P_{Kruskal-Wallis} = 0.04; P_adjusted = 0.055) have been found. No association between the AGTR1 c.1080*86A>C and CYP11B2 c.-344C>T and the Gensini score has been found. These results suggest that men who carry ACE c.2306-117_404 DD genotype and have high total cholesterol, high LDL cholesterol and low HDL cholesterol levels may be predisposed to the development of more severe CAD.     

A fluorescent redox sensor with tuneable oxidation potential

A fluorescent redox sensor was prepared by attachment of hydroquinones to the fluorophore rhodamine B; fluorescence is reversibly modulated by hydroquinone-centered chemical redox reactions, and oxidation potential of the sensor is tuneable by variation of hydroquinone structure.     

Unveiling functions of the visual cortex using task-specific deep neural networks

The human visual cortex enables visual perception through a cascade of hierarchical computations in cortical regions with distinct functionalities. Here, we introduce an AI-driven approach to discover the functional mapping of the visual cortex. We related human brain responses to scene images measured with functional MRI (fMRI) systematically to a diverse set of deep neural networks (DNNs) optimized to perform different scene perception tasks. We found a structured mapping between DNN tasks and brain regions along the ventral and dorsal visual streams. Low-level visual tasks mapped onto early brain regions, 3-dimensional scene perception tasks mapped onto the dorsal stream, and semantic tasks mapped onto the ventral stream. This mapping was of high fidelity, with more than 60% of the explainable variance in nine key regions being explained. Together, our results provide a novel functional mapping of the human visual cortex and demonstrate the power of the computational approach.     

Protein kinase C-mediated regulation of the renal Na(+)/dicarboxylate cotransporter, NaDC-1.

The Na(+)/dicarboxylate cotransporter of the renal proximal tubule, NaDC-1, reabsorbs Krebs cycle intermediates, such as succinate and citrate, from the tubular filtrate. Although long-term regulation of this transporter by chronic metabolic acidosis and K(+) deficiency is well documented, there is no information on acute regulation of NaDC-1. In the present study, the transport of succinate in Xenopus oocytes expressing NaDC-1 was inhibited up to 95% by two activators of protein kinase C, phorbol 12-myristate, 13-acetate (PMA) and sn-1, 2-dioctanoylglycerol (DOG). Activation of protein kinase A had no effect on NaDC-1 activity. The inhibition of NaDC-1 transport by PMA was dose-dependent, and could be prevented by incubation of the oocytes with staurosporine. Mutations of the two consensus protein kinase C phosphorylation sites in NaDC-1 did not affect inhibition by PMA. The inhibitory effects of PMA were partially prevented by cytochalasin D, which disrupts microfilaments and endocytosis. PMA treatment was also associated with a decrease of approximately 30% in the amount of NaDC-1 protein found on the plasma membrane. We conclude that the inhibition of NaDC-1 transport activity by PMA occurs by a combination of endocytosis and inhibition of transport activity.