Increased expression of bradykinin type-1 receptors in endothelium of intramyocardial coronary vessels in human failing hearts

In experimental animals, bradykinin type-1 receptors (BK-1Rs) are induced during inflammation and ischemia, and, by exerting either cardioprotective or cardiotoxic effects, they may contribute to the pathogenesis of heart failure. Nothing is known about the expression of BK-1Rs in human heart failure. Human heart tissue was obtained from excised hearts of patients undergoing cardiac transplantation (n = 13), due to idiopathic dilated cardiomyopathy (IDC; n = 7) or to coronary heart disease (CHD; n = 6), and from normal hearts (n = 6). The expression of BK-1Rs was analyzed by means of competitive RT-PCR, Western blot analysis, and immunohistochemistry. Expression of BK-1R mRNA was increased in both IDC (2.8-fold) and CHD (2.1-fold) hearts compared with normal hearts. The observed changes were verified at the protein level. Expression of BK-1Rs in failing hearts localized to the endothelium of intramyocardial coronary vessels and correlated with an increased expression of TNF-alpha in the vessel wall. Treatment of human coronary artery endothelial cells with TNF-alpha increases their BK-1R expression. These novel results show that BK-1Rs are induced in the endothelium of intramyocardial coronary vessels in failing human hearts and so may participate in the pathogenesis of heart failure.     

APP substitutions V715F and L720P alter PS1 conformation and differentially affect Abeta and AICD generation

The 37-43 amino acid Abeta peptide is the principal component of beta-amyloid deposits in Alzheimer's disease (AD) brain, and is derived by serial proteolysis of the amyloid precursor protein (APP) by beta- and gamma-secretase. gamma-Secretase also cleaves APP at Val50 in the Abeta numbering (epsilon cleavage), resulting in the release of a fragment called APP intracellular domain (AICD). The aim of this study was to determine whether amino acid substitutions in the APP transmembrane domain differentially affect Abeta and AICD generation. We found that the APPV715F substitution, which has been previously shown to dramatically decrease Abeta40 and Abeta42 while increasing Abeta38 levels, does not affect in vitro generation of AICD. Furthermore, we found that the APPL720P substitution, which has been previously shown to prevent in vitro generation of AICD, completely prevents Abeta generation. Using a fluorescence resonance energy transfer (FRET) method, we next found that both the APPV715F and APPL720P substitutions significantly increase the distance between the N- and C-terminus of presenilin 1 (PS1), which has been proposed to contain the catalytic site of gamma-secretase. In conclusion, both APPV715F and APPL720P change PS1 conformation with differential effects on Abeta and AICD production.     

New insights into butterfly-environment relationships using partitioning methods

Variation partitioning and hierarchical partitioning are novel statistical approaches that provide deeper understanding of the importance of different explanatory variables for biodiversity patterns than traditional regression methods. Using these methods, the variation in occupancy and abundance of the clouded apollo butterfly (Parnassius mnemosyne L.) was decomposed into independent and joint effects of larval and adult food resources, microclimate and habitat quantity. The independent effect of habitat quantity variables (habitat area and connectivity) captured the largest fraction of the variation in the clouded apollo patterns, but habitat connectivity had a major contribution only for occupancy data. The independent effects of resources and microclimate were higher on butterfly abundance than on occupancy. However, a considerable amount of variation in the butterfly patterns was accounted for by the joint effects of predictors and may thus be causally related to two or all three groups of variables. Abundance of the butterfly in the surroundings of the focal grid cell had a significant effect in all analyses, independently of the effects of other predictors. Our results encourage wider applications of partitioning methods in biodiversity studies.     

Effects of acid sphingomyelinase deficiency on male germ cell development and programmed cell death

Deficiency of acid sphingomyelinase (ASM), an enzyme responsible for producing a pro-apoptotic second messenger ceramide, has previously been shown to promote the survival of fetal mouse oocytes in vivo and to protect oocytes from chemotherapy-induced apoptosis in vitro. Here we investigated the effects of ASM deficiency on testicular germ cell development and on the ability of germ cells to undergo apoptosis. At the age of 20 weeks, ASM knock-out (ASMKO) sperm concentrations were comparable with wild-type (WT) sperm concentrations, whereas sperm motility was seriously affected. ASMKO testes contained significantly elevated levels of sphingomyelin at the age of 8 weeks as detected by high-performance, thin-layer chromatography. Electron microscopy revealed that the testes started to accumulate pathological vesicles in Sertoli cells and in the interstitium at the age of 21 days. Irradiation of WT and ASMKO mice did not elevate intratesticular ceramide levels at 16 h after irradiation. In situ end labeling of apoptotic cells also showed a similar degree of cell death in both groups. After a 21-day recovery period, the numbers of primary spermatocytes and spermatogonia at G2 as well as spermatids were essentially the same in the WT and ASMKO testes, as detected by flow cytometry. In serum-free cultures both ASMKO and WT germ cells showed a significant increase in the level of ceramide, as well as massive apoptosis. In conclusion, ASM is required for maintenance of normal sphingomyelin levels in the testis and for normal sperm motility, but not for testicular ceramide production or for the ability of the germ cells to undergo apoptosis.     

Exploring the effect of xenon on biomembranes

We report the initial findings of 100 ns molecular dynamics simulations of the role of cellular membranes in general anaesthesia. The effect of xenon on hydrated dipalmitoylphosphatidylcholine bilayers is described. The xenon atoms were found to prefer the interfacial and central regions of the bilayer. The presence of xenon was observed to lead to a small increase in the surface area, membrane thickness, and order of the acyl chains.     

Processing methods for differential analysis of LC/MS profile data

Background  

Liquid chromatography coupled to mass spectrometry (LC/MS) has been widely used in proteomics and metabolomics research. In this context, the technology has been increasingly used for differential profiling, i.e. broad screening of biomolecular components across multiple samples in order to elucidate the observed phenotypes and discover biomarkers. One of the major challenges in this domain remains development of better solutions for processing of LC/MS data.     

Reaction orders for thermal mortality of third instars of Mexican fruit fly (Diptera: Tephritidae)

Mexican fruit fly, Anastrepha ludens (Loew), is a quarantine pest of several fruit, including citrus, avocados, and mangoes, from extreme southern Texas to Costa Rica. To provide information for modeling heat phytosanitary treatments, third instars were heated with an aluminum heating block between 44 and 50 degrees C for time intervals up to those causing 100% mortality. At 44 and 50 degrees C, 100% mortality was achieved at 100 and 2 min, respectively. Each 2 degrees C increase in temperature resulted in a three-fourths reduction in the amount of time required to achieve 100% mortality. Mortality was modeled using thermal death kinetics, and the most suitable reaction order was the 0.5th. The thermal death activation energy was 560.7 kJ/mol, which is very similar to the value found for Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in a previous study, indicating similar modes of action for heat mortality. However, the Mexican fruit fly had a lower threshold for heat-induced mortality, resulting in less time at all temperatures studied to achieve 100% mortality compared with the Mediterranean fruit fly. This type of information being gathered for fruit flies could lead to the development of generic phytosanitary heat treatments, which are available for other major phytosanitary treatments, such as cold storage, methyl bromide fumigation, and ionizing irradiation.     

A high-density screen for linkage in multiple sclerosis

To provide a definitive linkage map for multiple sclerosis, we have genotyped the Illumina BeadArray linkage mapping panel (version 4) in a data set of 730 multiplex families of Northern European descent. After the application of stringent quality thresholds, data from 4,506 markers in 2,692 individuals were included in the analysis. Multipoint nonparametric linkage analysis revealed highly significant linkage in the major histocompatibility complex (MHC) on chromosome 6p21 (maximum LOD score [MLS] 11.66) and suggestive linkage on chromosomes 17q23 (MLS 2.45) and 5q33 (MLS 2.18). This set of markers achieved a mean information extraction of 79.3% across the genome, with a Mendelian inconsistency rate of only 0.002%. Stratification based on carriage of the multiple sclerosis–associated DRB1*1501 allele failed to identify any other region of linkage with genomewide significance. However, ordered-subset analysis suggested that there may be an additional locus on chromosome 19p13 that acts independent of the main MHC locus. These data illustrate the substantial increase in power that can be achieved with use of the latest tools emerging from the Human Genome Project and indicate that future attempts to systematically identify susceptibility genes for multiple sclerosis will have to involve large sample sizes and an association-based methodology.     

Current perspectives on cartilage and chondrocyte mechanobiology

It is well known that physiological forces are essential for the maintenance of normal composition and structure of articular cartilage. Although some of the mechanisms of mechanotransduction are known today, there are certainly many others left unrevealed. In order to understand the complicated systems present in articular cartilage, we have to bring together the data from all fields of cartilage mechanobiology. The 3rd Symposium on Mechanobiology of Cartilage and Chondrocyte was a good effort towards that goal.