Parathyroid hormone-related protein is a hypertrophy factor for human mesangial cells: Implications for diabetic nephropathy

Hypertrophy of human mesangial cells (HMC) is among the earliest characteristics in patients with diabetic nephropathy (DN). Recently, we observed the upregulation of parathyroid hormone (PTH)-related protein (PTHrP) in experimental DN, associated with renal hypertrophy. Herein, we first examined whether PTHrP was overexpressed in human DN, and next assessed the putative role of this protein on high glucose (HG)-induced HMC hypertrophy. As previously found in mice, kidneys from diabetic patients showed an increased tubular and glomerular immunostaining for PTHrP. In HMC, HG medium increased PTHrP protein expression associated with the development of hypertrophy as assessed by cell protein content. This effect was also induced by PTHrP(1-36). HG and PTHrP(1-36)-induced hypertrophy were associated with an increase in cyclin D1 and p27Kip1 protein expression, a decreased cyclin E expression, and the prevention of cyclin E/cdk2 complex activation. Both PTHrP neutralizing antiserum (α-PTHrP) and the PTH/PTHrP receptor antagonist (JB4250) were able to abolish HG induction of hypertrophy, the aforementioned changes in cell cycle proteins, and also TGF-β1 up-regulation. Moreover, the capability of both HG and PTHrP(1-36) to induce HMC hypertrophy was abolished by α-TGFβ1. These data show for the first time that PTHrP is upregulated in the kidney of patients with DN. Our findings also demonstrate that PTHrP acts as an important mediator of HG-induced HMC hypertrophy by modulating cell cycle regulatory proteins and TGF-β1.     

Density estimates of two endangered nocturnal lemur species from northern Madagascar: new results and a comparison of commonly used methods

Very little information is known of the recently described Microcebus tavaratra and Lepilemur milanoii in the Daraina region, a restricted area in far northern Madagascar. Since their forest habitat is highly fragmented and expected to undergo significant changes in the future, rapid surveys are essential to determine conservation priorities. Using both distance sampling and capture-recapture methods, we estimated population densities in two forest fragments. Our results are the first known density and population size estimates for both nocturnal species. In parallel, we compare density results from four different approaches, which are widely used to estimate lemur densities and population sizes throughout Madagascar. Four approaches (King, Kelker, Muller and Buckland) are based on transect surveys and distance sampling, and they differ from each other by the way the effective strip width is estimated. The fifth method relies on a capture-mark-recapture (CMR) approach. Overall, we found that the King method produced density estimates that were significantly higher than other methods, suggesting that it generates overestimates and hence overly optimistic estimates of population sizes in endangered species. The other three distance sampling methods provided similar estimates. These estimates were similar to those obtained with the CMR approach when enough recapture data were available. Given that Microcebus species are often trapped for genetic or behavioral studies, our results suggest that existing data can be used to provide estimates of population density for that species across Madagascar.     

The impact of future summer temperature on public health in Barcelona and Catalonia,Spain

Several epidemiological studies have reported associations between increases in summer temperatures and risks of premature mortality. The quantitative implications of predicted future increases in summer temperature, however, have not been extensively characterized. We have quantified these effects for the four main cities in Catalonia, Spain (Barcelona, Tarragona, Lleida, Girona). We first used case-crossover analysis to estimate the association between temperature and mortality for each of these cities for the period 1983 to 2006. These exposure–response (ER) functions were then combined with local measures of current and projected changes in population, mortality and temperature for the years 2025 and 2050. Predicted daily mean temperatures were based on the A1B greenhouse gas emission, “business-as-usual” scenario simulations derived from the ENSEMBLES project. Several different ER functions were examined and significant associations between temperature and mortality were observed for all four cities. For these four cities, the age-specific piecewise linear model predicts 520 (95%CI  340, 720) additional annual deaths attributable to the change in temperature in 2025 relative to the average from the baseline period of 1960–1990. For 2050, the estimate increases to 1,610 deaths per year during the warm season. For Catalonia as a whole, the point estimates for those two years are 720 and 2,330 deaths per year, respectively, or about 2 and 3% of the warm season. In comparing these predicted impacts with current causes of mortality, they clearly represent significant burdens to public health in Catalonia.     

Brief communication: Short- and long-term in vivo human buccal-dental microwear turnover

Buccal-dental microwear depends on the abrasive content of chewed foodstuffs and can reveal long-term dietary trends in human populations. However, in vivo experimental analyses of buccal microwear formation processes are scarce. Here, we report the effects of an abrasive diet on microwear rates in two adult volunteers at intervals of 8 days over a period of 1 month and document long-term turnover over 5 consecutive years in the same subjects under an ad libitum Mediterranean diet. Buccal microwear was analyzed on mandibular first molars using high-resolution replicas and scanning electron microscopy. Microwear turnover was assessed by recording the scratches lost and gained at each time point. Our results indicate that scratch formation on enamel surfaces increased with a highly abrasive diet compared to both pre-test and post-test ad libitum dietary controls. In the long-term analysis, scratch turnover was higher than expected, but no significant long-term trends in microwear density or length were observed, because microwear formation was compensated by scratch disappearance. Our results confirm that buccal microwear patterns on mandibular molars show a dynamic formation process directly related to the chewing of abrasive particles along with ingested food. In addition, the observed long-term stability of buccal microwear patterns makes them a reliable indicator of overall dietary habits.     

Direct analysis of bacterial viability in endotracheal tube biofilm from a pig model of methicillin-resistant Staphylococcus aureus pneumonia following antimicrobial therapy

Confocal laser scanning microscopy (CLSM) helps to observe the biofilms formed in the endotracheal tube (ETT) of ventilated subjects and to determine its structure and bacterial viability using specific dyes. We compared the effect of three different treatments (placebo, linezolid, and vancomycin) on the bacterial biofilm viability captured by CLSM. Eight pigs with pneumonia induced by methicillin-resistant Staphylococcus aureus (MRSA) were ventilated up to 96?h and treated with linezolid, vancomycin, or placebo (controls). ETT images were microscopically examined after staining with the live/dead(?) BacLight(?) Kit (Invitrogen, Barcelona, Spain) with a confocal laser scanning microscope. We analyzed 127 images obtained by CLSM. The median ratio of live/dead bacteria was 0.51, 0.74, and 1 for the linezolid, vancomycin, and control groups, respectively (P?=?0.002 for the three groups); this ratio was significantly lower for the linezolid group, compared with the control group (P?=?0.001). Images showed bacterial biofilm attached and non-attached to the ETT surface but growing within secretions accumulated inside ETT. Systemic treatment with linezolid is associated with a higher proportion of dead bacteria in the ETT biofilm of animals with MRSA pneumonia. Biofilm clusters not necessarily attach to the ETT surface.     

TcdB from hypervirulent Clostridium difficile exhibits increased efficiency of autoprocessing

TcdB, an intracellular bacterial toxin that inactivates small GTPases, is a major Clostridium difficile virulence factor. Recent studies have found that TcdB produced by emerging/hypervirulent strains of C. difficile is more potent than TcdB from historical strains, and in the current work, studies were performed to investigate the underlying mechanisms for this change in TcdB toxicity. Using a series of biochemical analyses we found that TcdB from a hypervirulent strain (TcdB_HV) was more efficient at autoprocessing than TcdB from a historical strain (TcdB_HIST). TcdB_HV and TcdB_HIST were activated by similar concentrations of IP6; however, the overall efficiency of processing was 20% higher for TcdB_HV. Using an activity‐based fluorescent probe (AWP19) an intermediate, activated but uncleaved, form of TcdB_HIST was identified, while only a processed form of TcdB_HV could be detected under the same conditions. Using a much higher concentration (200 µM) of the probe revealed an activated uncleaved form of TcdB_HV, indicating a preferential and more efficient engagement of intramolecular substrate than TcdB_HIST. Furthermore, a peptide‐based inhibitor (Ac‐GSL‐AOMK) was found to block the cytotoxicity of TcdB_HIST at a lower concentration than required to inhibit TcdB_HV. These findings suggest that TcdB_HV may cause increased cytotoxicity due to more efficient autoprocessing.     

Activation of the replicative DNA helicase: breaking up is hard to do

The precise duplication of the eukaryotic genome is accomplished by carefully coordinating the loading and activation of the replicative DNA helicase so that each replication origin is unwound and assembles functional bi-directional replisomes just once in each cell cycle. The essential Minichromosome Maintenance 2-7 (Mcm2-7) proteins, comprising the core of the replicative DNA helicase, are first loaded at replication origins in an inactive form. The helicase is then activated by recruitment of the Cdc45 and GINS proteins into a holo-helicase known as CMG (Cdc45, Mcm2-7, GINS). These steps are regulated by multiple mechanisms to ensure that Mcm2-7 loading can only occur during G1 phase, whilst activation of Mcm2-7 cannot occur during G1 phase. Here we review recent progress in understanding these critical reactions focusing on the mechanism of helicase loading and activation.     

Association between Ω3 and Ω6 fatty acid intakes and serum inflammatory markers in COPD

Dietary intake of polyunsaturated fatty acids, including omega-3 and omega-6, could modulate chronic obstructive pulmonary disease (COPD) persistent inflammation. We aimed to assess the relationship between dietary intake of omega-3 and omega-6 fatty acids and serum inflammatory markers in COPD. A total of 250 clinically stable COPD patients were included. Dietary data of the last 2 years were assessed using a validated food frequency questionnaire (122 items), which provided levels of three omega-3 fatty acids: docosahexaenoic acid, eicosapentaenoic acid and α-linolenic acid (ALA); and two omega-6 fatty acids: linoleic acid and arachidonic acid (AA). Inflammatory markers [C-reactive protein (CRP), interleukin (IL)-6, IL-8 and tumor necrosis factor alpha (TNFα)] were measured in serum. Fatty acids and inflammatory markers were dichotomised according to their median values, and their association was assessed using multivariate logistic regression. Higher intake of ALA (an anti-inflammatory omega-3 fatty acid) was associated with lower TNFα concentrations [adjusted odds ratio (OR)=0.46; P=.049]. Higher AA intake (a proinflammatory omega-6 fatty acid) was related to higher IL-6 (OR=1.96; P=.034) and CRP (OR=1.95; P=.039) concentrations. Therefore, this study provides the first evidence of an association between dietary intake of omega-3 and omega-6 fatty acids and serum inflammatory markers in COPD patients.     

Protein oxidation in Huntington disease

Huntington disease (HD) is an inherited neurodegenerative disorder caused by expansion of CAG repeats in the huntingtin gene, affecting initially the striatum and progressively the cortex. Oxidative stress, and consequent protein oxidation, has been described as important to disease progression. This review focuses on recent advances in the field, with a particular emphasis on the identified target proteins and the role that their oxidation has or might have in the pathophysiology of HD. Oxidation and the resulting inactivation and/or degradation of important proteins can explain the impairment of several metabolic pathways in HD. Oxidation of enzymes involved in ATP synthesis can account for the energy deficiency observed. Impairment of protein folding and degradation can be due to oxidation of several heat shock proteins and Valosin-containing protein. Oxidation of two enzymes involved in the vitamin B6 metabolism could result in decreased availability of pyridoxal phosphate, which is a necessary cofactor in transaminations, the kynurenine pathway and the synthesis of glutathione, GABA, dopamine and serotonin, all of which have a key role in HD pathology. In addition, protein oxidation often contributes to oxidative stress, aggravating the molecular damage inside the cell.