The Chinese bamboo leaf odorous frog (Rana (Odorrana) versabilis) and North American Rana frogs share the same families of skin antimicrobial peptides.

The Chinese bamboo leaf odorous frog (Rana (Odorrana) versabilis) and the North American pickerel frog (Rana palustris) occupy different ecological niches on two different continents with no overlap in geographical distribution. R. palustris skin secretions contain a formidable array of antimicrobial peptides including homologs of brevinin-1, esculentin-1, esculentin-2, ranatuerin-2, a temporin and a family of peptides considered of unique structural attributes when isolated, palustrins 1–3. Here we describe the structures of mature peptides and precursors of eight putative antimicrobial peptides from the skin secretion of the Chinese bamboo leaf odorous frog (Rana (Odorrana) versabilis). Each peptide represents a structural homolog of respective peptide families isolated from R. palustris, including two peptides identical in primary structure to palustrin 1c and palustrin 3b. Additionally, two peptides were found to be structural homologs of ranatuerin 2B and ranatuerin 2P from the closely-related North American species, Rana berlandieri (the Rio Grande leopard frog) and Rana pipiens (the Northern leopard frog), respectively. Both palustrins and ranatuerins have hitherto been considered unique to North American ranid frogs. The use of primary structures of amphibian skin antimicrobial peptides is thus questionable as a taxonomic device or alternatively, the micro-evolution and/or ancestry of ranid frogs is more highly complex than previously thought.

Novel brevinins from Chinese piebald odorous frog (Huia schmackeri) skin deduced from cloned biosynthetic precursors

Antimicrobial peptides represent the most characterized and diverse class of peptides within the defensive skin secretions of anuran amphibians. With an ever expanding database of primary structures, the current accepted rules for nomenclature have become increasingly difficult to apply to peptides whose primary structural attributes are either unique or that fall between those that define existing groups. An additional factor that adds to the confusion is the regular re-classification or revision of existing taxa. In the present study, we have identified five new antimicrobial peptide homologs in the defensive skin secretion of the Chinese piebald odorous frog, Huia schmackeri (formerly Rana (Odorrana) schmackeri), by cloning of their respective biosynthetic precursors. As these peptides are obvious homologs of the brevinin-1 and brevinin-2 families we have named these in accordance: (1) brevinin-1HS1, (2) brevinin-2HS1, (3) brevinin-2HS2, (4) brevinin-2HS3 and (5) brevinin-1HS2. The reasons for adopting these names are discussed. It is clear that with an ever-increasing number of amphibian skin antimicrobial peptides appearing in the literature that a consistent nomenclature scheme needs to be established.

Species boundaries and phylogenetic relationships within the green algal genus Codium (Bryopsidales) based on plastid DNA sequences

Despite the potential model role of the green algal genus Codium for studies of marine speciation and evolution, there have been difficulties with species delimitation and a molecular phylogenetic framework was lacking. In the present study, 74 evolutionarily significant units (ESUs) are delimited using 227 rbcL exon 1 sequences obtained from specimens collected throughout the genus' range. Several morpho-species were shown to be poorly defined, with some clearly in need of lumping and others containing pseudo-cryptic diversity. A phylogenetic hypothesis of 72 Codium ESUs is inferred from rbcL exon 1 and rps3-rp/16 sequence data using a conventional nucleotide substitution model (GTR + Gamma + I), a codon position model and a covariotide (covarion) model, and the fit of a multitude of substitution models and alignment partitioning strategies to the sequence data is reported. Molecular clock tree rooting was carried out because out-group rooting was probably affected by phylogenetic bias. Several aspects of the evolution of morphological features of Codium are discussed and the inferred phylogenetic hypothesis is used as a framework to study the biogeography of the genus, both at a global scale and within the Indian Ocean. (c) 2007 Elsevier Inc. All rights reserved.

A quantitative determination of reaction mechanisms from density functional theory calculations: Fischer-Tropsch synthesis on flat and stepped cobalt surfaces

We systematically investigated the mechanism of the C-1 + C-1 coupling reactions using density functional theory. The activation energies of C-1 + C-1 coupling and carbon hydrogenation reactions on both flat and stepped surfaces were calculated and analyzed. Moreover, the coverages of adsorbed C-1 species were estimated, and the reaction rates of all possible C-1 + C-1 coupling pathways were quantitatively evaluated. The results suggest that the reactions of CH2 + CH2 and CH3 + C at steps are most likely to be the key C-1 + C-1 coupling steps in FT synthesis on Co catalysts. The reactions of C-2 + C-1 and C-3 + C-1 coupling also were studied; the results demonstrate that in addition to the pathways of RCH + CH2 and RCH2 + C, the coupling of RC + C and RC + CH also may contribute to the chain growth after C-1. (C) 2008 Elsevier Inc. All rights reserved.

Chitosan nanoparticle as protein delivery carrier - Systematic examination of fabrication conditions for efficient loading and release

Chitosan nanoparticles fabricated via different preparation protocols have been in recent years widely studied as carriers for therapeutic proteins and genes with varying degree of effectiveness and drawbacks. This work seeks to further explore the polyionic coacervation fabrication process, and associated processing conditions under which protein encapsulation and subsequent release can be systematically and predictably manipulated so as to obtain desired effectiveness. BSA was used as a model protein which was encapsulated by either incorporation or incubation method, using the polyanion tripolyphosphate (TPP) as the coacervation crosslink agent to form chitosan-BSA-TPP nanoparticles. The BSA-loaded chitosan-TPP nanoparticles were characterized for particle size, morphology, zeta potential, BSA encapsulation efficiency, and subsequent release kinetics, which were found predominantly dependent on the factors of chitosan molecular weight, chitosan concentration, BSA loading concentration, and chitosan/TPP mass ratio. The BSA loaded nanoparticles prepared under varying conditions were in the size range of 200-580 nm, and exhibit a high positive zeta potential. Detailed sequential time frame TEM imaging of morphological change of the BSA loaded particles showed a swelling and particle degradation process. Initial burst released due to surface protein desorption and diffusion from sublayers did not relate directly to change of particle size and shape, which was eminently apparent only after 6 h. It is also notable that later stage particle degradation and disintegration did not yield a substantial follow-on release, as the remaining protein molecules, with adaptable 3-D conformation, could be tightly bound and entangled with the cationic chitosan chains. In general, this study demonstrated that the polyionic coacervation process for fabricating protein loaded chitosan nanoparticles offers simple preparation conditions and a clear processing window for manipulation of physiochemical properties of the nanoparticles (e.g., size and surface charge), which can be conditioned to exert control over protein encapsulation efficiency and subsequent release profile. The weakness of the chitosan nanoparticle system lies typically with difficulties in controlling initial burst effect in releasing large quantities of protein molecules. (C) 2007 Elsevier B.V. All rights reserved.

Improved fault diagnosis in multivariate systems using regression-based reconstruction

Subspace monitoring has recently been proposed as a condition monitoring tool that requires considerably fewer variables to be analysed compared to dynamic principal component analysis (PCA). This paper analyses subspace monitoring in identifying and isolating fault conditions, which reveals that the existing work suffers from inherent limitations if complex fault senarios arise. Based on the assumption that the fault signature is deterministic while the monitored variables are stochastic, the paper introduces a regression-based reconstruction technique to overcome these limitations. The utility of the proposed fault identification and isolation method is shown using a simulation example and the analysis of experimental data from an industrial reactive distillation unit.

Is hyperfiltration associated with the future risk of developing diabetic nephropathy? A meta-analysis.

Aims/hypothesis Glomerular hyperfiltration is a well established phenomenon occurring early in some patients with type 1 diabetes. However, there is no consistent answer regarding whether hyperfiltration predicts later development of nephropathy. We performed a systematic review and meta-analysis of observational studies that compared the risk of developing diabetic nephropathy in patients with and without glomerular hyperfiltration and also explored the impact of baseline GFR.

Methods A systematic review and meta-analysis was carried out. Cohort studies in type 1 diabetic participants were included if they contained data on the development of incipient or overt nephropathy with baseline measurement
of GFR and presence or absence of hyperfiltration.

Results We included ten cohort studies following 780 patients. After a study median follow-up of 11.2 years, 130 patients had developed nephropathy. Using a random effects model, the pooled odds of progression to a minimum
of microalbuminuria in patients with hyperfiltration was 2.71 (95% CI 1.20–6.11) times that of patients with normofiltration. There was moderate heterogeneity (heterogeneity test p=0.05, measure of degree of inconsistency=48%) and some evidence of funnel plot asymmetry, possibly due to publication bias. The pooled weighted mean difference in baseline GFR was 13.8 ml min-1 1.73 m-2 (95% CI 5.0–22.7) greater in the group progressing to nephropathy than in those not progressing (heterogeneity test p<0.01).

Conclusions/interpretation In published studies, individuals with glomerular hyperfiltration were at increased risk of progression to diabetic nephropathy using study level data. Further larger studies are required to explore this relationship and the role of potential confounding variables.

Abnormal integrity of association fiber tracts in amnestic mild cognitive impairment.

The association fiber tracts integrity of the inter-hemispheric and within-hemispheric communication was poor understood in amnestic type mild cognitive impairment (aMCI) patients by diffusion tensor imaging (DTI). A region of interest-based DTI approach was applied to explore fiber tract differences between 22 aMCI patients and 22 well-matched normal aging. Correlations were also sought between fractional anisotropy (FA) values and the cognitive performance scores in the aMCI patients. Extensive impairment of association fiber tracts integrity was observed in aMCI patients, including bilateral inferior fronto-occipital fascicles, the genu of corpus callosum, bilateral cingulate bundles and bilateral superior longitudinal fascicles II (SLE II) subcomponent. In addition, the FA value of right SLE II was significantly negatively correlated to the performance of Trail Making Test A and B, whilst the values of right posterior cingulate bundle was significantly positive correlation with MMSE score. As aMCI is a putative prodromal syndrome to Alzheimer's disease (AD), this study suggested that investigation of association fiber tracts between remote cortexes may yield important new data to predict whether a patient will eventually develop AD.

Investigation of DNA polymorphisms in SMAD genes for genetic predisposition to diabetic nephropathy in patients with type 1 diabetes mellitus

Aims/hypothesis: SMAD proteins are involved in multiple signalling pathways and are key modulators of gene expression. We hypothesised that genetic variation in selected SMAD genes contributes to susceptibility to diabetic nephropathy. Methods: We selected 13 haplotype tag (ht) single nucleotide polymorphisms (SNPs) from 67 variants identified by resequencing the SMAD2 and SMAD3 genes. For SMAD1, SMAD4 and SMAD5 genes, genotype data were downloaded for 217 SNPs from Phase II of the International HapMap project. Of these, 85 SNPs met our inclusion criteria, resulting in the selection of 13 tag SNPs for further investigation. A case-control approach was employed, using 267 nephropathic patients and 442 controls with type 1 diabetes from Ireland. Two further populations (totalling 1,407 patients, 2,238 controls) were genotyped to validate initial findings. Genotyping was conducted using iPLEX, TaqMan and gel electrophoresis.
Results: The distribution of genotypes was in Hardy-Weinberg equilibrium. Analysis by the ? 2 test of genotype and allele frequencies in patients versus controls in the Irish population (n?=?709) revealed evidence for the association of one allele at 5% level of significance (rs10515478, p uncorrected?=?0.006; p corrected?=?0.04). This finding represents a relatively small difference in allele frequency of 6.4% in the patient group compared with 10.7% in the control group; this difference was not supported in subsequent investigations using DNA from European individuals with similar phenotypic characteristics.
Conclusions/interpretation: We selected an appropriate subset of variants for the investigation of common genetic risk factors and assessed SMAD1 to SMAD5 genes for association with diabetic nephropathy. We conclude that common polymorphisms in these genes do not strongly influence genetic susceptibility to diabetic nephropathy in white individuals with type 1 diabetes mellitus.

Nature or nurture BMI and blood pressure at 90. Findings from the Belfast Elderly longitudinal free-living aging study Belfast

Hypertension is a key risk factor for stroke, cardiovascular disease and dementia. Although the link between weight, sodium and hypertension is established in younger people, little is known about their inter-relationship in people beyond 80 years of age. Associations between blood pressure, anthropometric indices and sodium were investigated in 495 apparently healthy, community-living participants (age 90, SD 4.8; range 80–106), from the cross-sectional Belfast Elderly Longitudinal Free-living Aging STudy (BELFAST) study. In age-sex-adjusted logistic regression models, blood pressure =140/90 mmHg significantly associated with body mass index (BMI) [odds ratio (OR)?=?1.28/ kg/m2], with weight (OR?=?1.22/kg) approaching significance (P?=?0.07). In further age-sex-adjusted models, blood pressure above the 120/80 mmHg normotensive reference value significantly associated with BMI (OR?=?1.44/kg/m2), weight (OR?=?1.36/kg), skin-fold-thickness (OR?=?1.33/mm) and serum sodium (OR?=?1.37 mmol/l). In BELFAST participants over 80 years old, blood pressure =140/90 mmHg is associated with BMI, in apparently similar ways to younger groups.