Routine analysis of short-chain fatty acids for anaerobic bacteria identification using capillary electrophoresis and indirect ultraviolet detection

The diagnosis of anaerobes can be difficult to perform, using classical biochemical tests. Characterization of metabolic end-products such as short-chain fatty acids (SCFA) was often used because of their reproducible biosynthesis. Despite this, SCFA are difficult to study using gas chromatography, due to their high volatility. Furthermore, the treatment of the samples are long and fastidious. Capillary electrophoresis and indirect UV detection (CE-indirect UV) is a well-known analytical method to study inorganic or organic anions. In this work, we validate the analysis of SCFA using CE-indirect UV detection. To do this, we studied the culture media of 98 anaerobic strains for the detection and quantitation of the following acids: succinic, pyruvic, acetic, lactic, propionic, 2-hydroxybutyric, butyric, 2-hydroxyvaleric, isovaleric, isocaproic, and 3-phenylpropionic. We verified that the CE-indirect UV detection analysis of SCFA for taxonomical data can be used as a mean for rapid identification for the study of anaerobes.     

Microstructure of the neocortex: comparative aspects

The appearance of the neocortex, its expansion, and its differentiation in mammals, represents one of the principal episodes in the evolution of the vertebrate brain. One of the fundamental questions in neuroscience is what is special about the neocortex of humans and how does it differ from that of other species? It is clear that distinct cortical areas show important differences within both the same and different species, and this has led to some researchers emphasizing the similarities whereas others focus on the differences. In general, despite of the large number of different elements that contribute to neocortical circuits, it is thought that neocortical neurons are organized into multiple, small repeating microcircuits, based around pyramidal cells and their input-output connections. These inputs originate from extrinsic afferent systems, excitatory glutamatergic spiny cells (which include other pyramidal cells and spiny stellate cells), and inhibitory GABAergic interneurons. The problem is that the neuronal elements that make up the basic microcircuit are differentiated into subtypes, some of which are lacking or highly modified in different cortical areas or species. Furthermore, the number of neurons contained in a discrete vertical cylinder of cortical tissue varies across species. Additionally, it has been shown that the neuropil in different cortical areas of the human, rat and mouse has a characteristic layer specific synaptology. These variations most likely reflect functional differences in the specific cortical circuits. The laminar specific similarities between cortical areas and between species, with respect to the percentage, length and density of excitatory and inhibitory synapses, and to the number of synapses per neuron, might be considered as the basic cortical building bricks. In turn, the differences probably indicate the evolutionary adaptation of excitatory and inhibitory circuits to particular functions.     

Mutations that disrupt the carboxyl-terminus of gamma-sarcoglycan cause muscular dystrophy

Recently, mutations in the genes encoding several of the dystrophin- associated proteins have been identified that produce phenotypes ranging from severe Duchenne-like autosomal recessive muscular dystrophy to the milder limb-girdle muscular dystrophies (LGMDs). LGMD type 2C is generally associated with a more severe clinical course and is prevalent in northern Africa. A previous study identified a single base pair deletion in the gene encoding the dystrophin-associated protein gamma-sarcoglycan in a number of Tunisian muscular dystrophy patients. To investigate whether gamma-sarcoglycan gene mutations cause autosomal recessive muscular dystrophy in other populations, we studied 50 muscular dystrophy patients from the United States and Italy. The muscle biopsies from these 50 patients showed no abnormality of dystrophin but did show diminished immunostaining for the dystrophin- associated protein alpha-sarcoglycan. Four patients with a severe muscular dystrophy phenotype were identified with homozygous, frameshifting mutations in gamma-sarcoglycan. Two of the four have microdeletions that disrupt the distal carboxyl-terminus of gamma- sarcoglycan yet result in a complete absence of gamma-and beta- sarcoglycan suggesting the importance of this region for stability of the sarcoglycan complex. This region of gamma-sarcoglycan, like beta- sarcoglycan, has a number of cysteine residues similar to those in epidermal growth factor cysteine-rich regions.      

Gene variants associated with deep vein thrombosis

Irene D. Bezemer, MSc; Lance A. Bare, PhD; Carine J. M. Doggen, PhD; Andre R. Arellano, BS; Carmen Tong, BS; Charles M. Rowland, MS; Joseph Catanese, BS; Bradford A. Young, PhD; Pieter H. Reitsma, PhD; James J. Devlin, PhD; Frits R. Rosendaal, MD, PhD

JAMA. 2008;299(11):1306-1314.

Context  The genetic causes of deep vein thrombosis (DVT) are not fully understood.

Objective  To identify single-nucleotide polymorphisms (SNPs) associated with DVT.

Design, Setting, and Patients  We used 3 case-control studies of first DVT. A total of 19 682 gene-centric SNPs were genotyped in 443 cases and 453 controls from the Leiden Thrombophilia Study (LETS, 1988-1992). Twelve hundred six SNPs associated with DVT were reinvestigated in the Multiple Environmental and Genetic Assessment of Risk Factors for Venous Thrombosis study (MEGA-1, 1999-2004) in a subset of 1398 cases and 1757 controls. Nine SNPs associated with DVT in both LETS and MEGA-1 were investigated a third time in 1314 cases and 2877 controls from MEGA-2, a second subset of MEGA. Additional SNPs close to one SNP in CYP4V2 were genotyped in LETS and MEGA-1.

Main Outcome Measure  Odds ratios (ORs) for DVT were estimated by logistic regression. False discovery rates served to investigate the effect of multiple hypothesis testing.

Results  Of 9 SNPs genotyped in MEGA-2, 3 were strongly associated with DVT (P < .05; false discovery rate .10): rs13146272 in CYP4V2 (risk allele frequency, 0.64), rs2227589 in SERPINC1 (risk allele frequency, 0.10), and rs1613662 in GP6 (risk allele frequency, 0.84). The OR for DVT per risk allele was 1.24 (95% confidence interval [95%CI], 1.11-1.37) for rs13146272, 1.29 (95% CI, 1.10-1.49) for rs2227589, and 1.15 (95% CI, 1.01-1.30) for rs1613662. In the region of CYP4V2, we identified 4 additional SNPs (in CYP4V2, KLKB1, and F11) that were also associated with both DVT (highest OR per risk allele, 1.39; 95% CI, 1.11-1.74) and coagulation factor XI level (highest increase per risk allele, 8%; 95% CI, 5%-11%).

Conclusions  We identified SNPs in several genes that were associated with DVT. We also found SNPs in the region around the SNP in CYP4V2 (rs13146272) that were associated with both DVT and factor XI levels. These results show that common genetic variation plays an important role in determining thrombotic risk.

     

Unmasking Glucose Metabolism Alterations in Stable Renal Transplant Recipients: A Multicenter Study

Background and objectives: Emerging information indicates that glucose metabolism alterations are common after renal transplantation and are associated with carotid atheromatosis. The aims of this study were to investigate the prevalence of different glucose metabolism alterations in stable recipients as well as the factors related to the condition.Design, setting, participants, & measurements: A multicenter, cross-sectional study was conducted of 374 renal transplant recipients without pre- or posttransplantation diabetes. A standard 75-g oral glucose tolerance test was performed.Results: Glucose metabolism alterations were present in 119 (31.8%) recipients: 92 (24.6%) with an abnormal oral glucose tolerance test and 27 (7.2%) with isolated impaired fasting glucose. The most common disorder was impaired glucose tolerance (17.9%), and an abnormal oral glucose tolerance test was observed for 21.5% of recipients with a normal fasting glucose. By multivariate analysis, age, prednisone dosage, triglyceride/high-density lipoprotein cholesterol ratio, and β blocker use were shown to be factors related to glucose metabolism alterations. Remarkably, triglyceride levels, triglyceride/high-density lipoprotein cholesterol ratio, and the proportion of recipients with impaired fasting glucose were already higher throughout the first posttransplantation year in recipients with a current glucose metabolism alteration as compared with those without the condition.Conclusions: Glucose metabolism alterations are common in stable renal transplant recipients, and an oral glucose tolerance test is required for its detection. They are associated with a worse metabolic profile, which is already present during the first posttransplantation year. These findings may help planning strategies for early detection and intervention.New-onset diabetes after renal transplantation (NODAT) represents a serious metabolic complication with a negative impact on graft and patient survival, as well as on cardiovascular morbidity and mortality (1–5). Emerging information indicates that less severe glucose metabolism alterations (GMA), such as impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), are also highly prevalent (6–10) and are associated with increased cardiovascular risk in the general population (11,12). In the renal transplant setting, Cosio et al. (13) reported that IFG was associated with a significantly higher incidence of posttransplantation cardiac events and peripheral vascular disease. In addition, an abnormal oral glucose tolerance test (OGTT) in stable renal transplant recipients is related to carotid atheromatosis (14), a surrogate marker of cardiovascular morbidity and mortality.Recently developed consensus guidelines have suggested that the diagnosis of GMA in renal transplant recipients should be based on regular screening of fasting blood glucose (1); however, other studies demonstrated that such an approach underestimated the true incidence of NODAT and ignored the important diagnosis of IGT, which can be made only with a simple and inexpensive OGTT (6–10). Single-center studies have reported that stable renal transplant recipients with IFG and/or IGT are older, exhibit higher body mass index and dyslipidemia, and more frequently are on β blockers (6–8); however, multicenter studies including a higher number of patients and reflecting different clinical practices may contribute to more accurate characterization of the clinical profile of recipients with GMA. Because these conditions are modifiable cardiovascular risk factors, providing the clinician with simple tools to suspect the condition may be helpful to indicate a more thorough investigation with OGTT and apply preventive interventions. The aims of this multicenter, cross-sectional study were to investigate the prevalence of GMA beyond 1 yr of transplantation and, in addition, the clinical profile and factors related to these conditions.