Liver kidney microsomes type 1 antibodies are associated with 80% reduction of the CYP2D6 activity in patients with chronic hepatitis C

Introduction Liver kidney microsomal type 1 (LKM-1) antibodies have been shown to decrease CYP2D6 activity in vitro. We investigated whether LKM-1 antibodies might reduce CYP2D6 activity also in vivo.Materials and Methods All patients with chronic hepatitis C and LKM-1 antibodies enrolled in the Swiss Hepatitis C Cohort Study (SCCS) were assessed: ten were eligible and fi tted to patients without LKM-1 antibodies. Patients were genotyped for CYP2D6 variants to exclude individuals with a poor metabolizer genotype. CYP2D6 activity was measured by a specifi c substrate using the dextromethorphan/dextrorphan (DEM/DOR) metabolic ratio to classify patients into four activity phenotypes (i.e. ultrarapid, extensive, intermediate and poor metabolizers). The concordance between phenotype based on DEM/DOR ratio and phenotype expected from genotype was examined in LKM-1 positive and negative patients. Groups were compared with respect to the DEM/DOR metabolic ratio.Results All patients had a CYP2D6 extensive metabolizer genotype. The observed phenotype was concordant with CYP2D6 genotype in most LKM-negative patients, whereas only three (30%) LKM-1 positive patients had a concordant phenotype (six presented an intermediate and one a poor metabolizer phenotype). The median DEM/DOR ratio was six-fold higher in LKM-1 positive than in LKM-1 negative patients (0.096 vs. 0.016, p = 0.004), indicating that CYP2D6 metabolic function was significantly reduced in the presence of LKM-1 antibodies.Conclusion In chronic hepatitis C patients with LKM-1 antibodies, the CYP2D6 metabolic activity was on average reduced by 80%. The impact of LKM-1 antibodies on CYP2D6-mediated drug metabolism pathways warrants further translational studies in the setting of new protease inhibitor therapies

Ultrastructure of the membrane attack complex of complement: detection of the tetramolecular C9-polymerizing complex C5b-8.

The ultrastructure of the membrane attack complex (MAC) of complement had been described as representing a hollow cylinder of defined dimensions that is composed of the proteins C5b, C6, C7, C8, and C9. After the characteristic cylindrical structure was identified as polymerized C9 [poly(C9)], the question arose as to the ultrastructural identity and topology of the C9-polymerizing complex C5b-8. An electron microscopic analysis of isolated MAC revealed an asymmetry of individual complexes with respect to their length. Whereas the length of one boundary (+/- SEM) was always 16 +/- 1 nm, the length of the other varied between 16 and 32 nm. In contrast, poly(C9), formed spontaneously from isolated C9, had a uniform tubule length (+/- SEM) of 16 +/- 1 nm. On examination of MAC-phospholipid vesicle complexes, an elongated structure was detected that was closely associated with the poly(C9) tubule and that extended 16-18 nm beyond the torus of the tubule and 28-30 nm above the membrane surface. The width of this structure varied depending on its two-dimensional projection in the electron microscope. By using biotinyl C5b-6 in the formation of the MAC and avidin-coated colloidal gold particles for the ultrastructural analysis, this heretofore unrecognized subunit of the MAC could be identified as the tetramolecular C5b-8 complex. Identification also was achieved by using anti-C5 Fab-coated colloidal gold particles. A similar elongated structure of 25 nm length (above the surface of the membrane) was observed on single C5b-8-vesicle complexes. It is concluded that the C5b-8 complex, which catalyzes poly(C9) formation, constitutes a structure of discrete morphology that remains as such identifiable in the fully assembled MAC, in which it is closely associated with the poly(C9) tubule.

In vivo synergism of ceftobiprole and vancomycin against experimental endocarditis due to vancomycin-intermediate Staphylococcus aureus.

The efficacy of ceftobiprole combined with vancomycin was tested against two vancomycin-intermediate Staphylococcus aureus (VISA) strains, PC3 and Mu50, in rats with experimental endocarditis. Animals with infected aortic vegetations were treated for 3 days with doses simulating the kinetics after intravenous administration in humans of (i) the standard dose of ceftobiprole of 500 mg every 12 h (b.i.d.) (SD-ceftobiprole), (ii) a low dose of ceftobiprole of 250 mg b.i.d. (LD-ceftobiprole), (iii) a very low dose of ceftobiprole of 125 mg b.i.d. (VLD-ceftobiprole), (iv) SD-vancomycin of 1 g b.i.d., or (v) LD- or VLD-ceftobiprole combined with SD-vancomycin. Low dosages of ceftobiprole were purposely used to highlight positive drug interactions. Treatment with SD-ceftobiprole sterilized 12 of 14 (86%) and 10 of 13 (77%) vegetations infected with PC3 and Mu50, respectively (P < 0.001 versus controls). In comparison, LD-ceftobiprole sterilized 10 of 11 (91%) vegetations infected with PC3 (P < 0.01 versus controls) but only 3 of 12 (25%) vegetations infected with Mu50 (P > 0.05 versus controls). VLD-ceftobiprole and SD-vancomycin alone were ineffective against both strains (≤8% sterile vegetations). In contrast, the combination of VLD-ceftobiprole and SD-vancomycin sterilized 7 of 9 (78%) and 6 of 14 (43%) vegetations infected with PC3 and Mu50, respectively, and the combination of LD-ceftobiprole and SD-vancomycin sterilized 5 of 6 (83%) vegetations infected with Mu50 (P < 0.05 versus controls and monotherapy). Thus, ceftobiprole monotherapy simulating standard therapeutic doses was active against VISA experimental endocarditis. Moreover, subtherapeutic LD- and VLD-ceftobiprole synergized with ineffective vancomycin to restore efficacy. Hence, combining ceftobiprole with vancomycin broadens the therapeutic margin of these two compounds against VISA infections.

Novel loci for adiponectin levels and their influence on type 2 diabetes and metabolic traits: a multi-ethnic meta-analysis of 45,891 individuals.

Circulating levels of adiponectin, a hormone produced predominantly by adipocytes, are highly heritable and are inversely associated with type 2 diabetes mellitus (T2D) and other metabolic traits. We conducted a meta-analysis of genome-wide association studies in 39,883 individuals of European ancestry to identify genes associated with metabolic disease. We identified 8 novel loci associated with adiponectin levels and confirmed 2 previously reported loci (P = 4.5×10(-8)-1.2×10(-43)). Using a novel method to combine data across ethnicities (N = 4,232 African Americans, N = 1,776 Asians, and N = 29,347 Europeans), we identified two additional novel loci. Expression analyses of 436 human adipocyte samples revealed that mRNA levels of 18 genes at candidate regions were associated with adiponectin concentrations after accounting for multiple testing (p<3×10(-4)). We next developed a multi-SNP genotypic risk score to test the association of adiponectin decreasing risk alleles on metabolic traits and diseases using consortia-level meta-analytic data. This risk score was associated with increased risk of T2D (p = 4.3×10(-3), n = 22,044), increased triglycerides (p = 2.6×10(-14), n = 93,440), increased waist-to-hip ratio (p = 1.8×10(-5), n = 77,167), increased glucose two hours post oral glucose tolerance testing (p = 4.4×10(-3), n = 15,234), increased fasting insulin (p = 0.015, n = 48,238), but with lower in HDL-cholesterol concentrations (p = 4.5×10(-13), n = 96,748) and decreased BMI (p = 1.4×10(-4), n = 121,335). These findings identify novel genetic determinants of adiponectin levels, which, taken together, influence risk of T2D and markers of insulin resistance.

Comparison between computational alanine scanning and per-residue binding free energy decomposition for protein-protein association using MM-GBSA: application to the TCR-p-MHC complex.

Recognition by the T-cell receptor (TCR) of immunogenic peptides (p) presented by Class I major histocompatibility complexes (MHC) is the key event in the immune response against virus-infected cells or tumor cells. A study of the 2C TCR/SIYR/H-2K(b) system using a computational alanine scanning and a much faster binding free energy decomposition based on the Molecular Mechanics-Generalized Born Surface Area (MM-GBSA) method is presented. The results show that the TCR-p-MHC binding free energy decomposition using this approach and including entropic terms provides a detailed and reliable description of the interactions between the molecules at an atomistic level. Comparison of the decomposition results with experimentally determined activity differences for alanine mutants yields a correlation of 0.67 when the entropy is neglected and 0.72 when the entropy is taken into account. Similarly, comparison of experimental activities with variations in binding free energies determined by computational alanine scanning yields correlations of 0.72 and 0.74 when the entropy is neglected or taken into account, respectively. Some key interactions for the TCR-p-MHC binding are analyzed and some possible side chains replacements are proposed in the context of TCR protein engineering. In addition, a comparison of the two theoretical approaches for estimating the role of each side chain in the complexation is given, and a new ad hoc approach to decompose the vibrational entropy term into atomic contributions, the linear decomposition of the vibrational entropy (LDVE), is introduced. The latter allows the rapid calculation of the entropic contribution of interesting side chains to the binding. This new method is based on the idea that the most important contributions to the vibrational entropy of a molecule originate from residues that contribute most to the vibrational amplitude of the normal modes. The LDVE approach is shown to provide results very similar to those of the exact but highly computationally demanding method.

Insights into neuronal cell metabolism using NMR spectroscopy: uridyl diphosphate N-acetyl-glucosamine as a unique metabolic marker.

Making the switch: Compounds 1 and 2 are used as metabolic markers for NMR detection. When neuronal cells switch to a glycolytic state, an uneven distribution of (13) C in the N-acetyl group results, thus giving a mixture of the metabolites 1 and 2. It is therefore possible to monitor flux through different metabolic pathways, such as glycolysis, the tricarboxylic acid cycle, and the hexosamine biosynthetic pathway, using a single molecule.

Dysfonction métabolique et stress chronique: un nouveau regard sur la pandémie de "diabésité" [Metabolic dysfunction and chronic stress: a new sight at "diabesity" pandemic]

Chronic stress in Western society can activate the autonomus, neuroendocrine and inflammatory/immunlogic systems. Chronic exposure to stressors can indeed stimulate the hypothalamic-pituitary-adrenal axis and induce a disbalance between anabolic and catabolic hormones, responsible of an increased in visceral fat and of insulin resistance. These metabolic consequences can lead to pre-diabetes. Exposure to chronic stress results in allostatic load and its pathophysiologic consequences. The knowledge of this mecanisms and the cardiovascular and metabolic risk related, should influence our way of thinking about patient care. To decrease allostatic load, practitioners can rely on therapeutic relation. Therapeutic education is one of the skill that can be use to create therapeutic relation.

Metabolic effects of parenteral nutrition enriched with n-3 polyunsaturated fatty acids in critically ill patients

BACKGROUND & AIMS: n-3 fatty acids are expected to downregulate the inflammatory responses, and hence may decrease insulin resistance. On the other hand, n-3 fatty acid supplementation has been reported to increase glycemia in type 2 diabetes. We therefore assessed the effect of n-3 fatty acids delivered with parenteral nutrition on glucose metabolism in surgical intensive care patients. METHODS: Twenty-four surgical intensive care patients were randomized to receive parenteral nutrition providing 1.25 times their fasting energy expenditure, with 0.25 g of either an n-3 fatty acid enriched-or a soy bean-lipid emulsion. Energy metabolism, glucose production, gluconeogenesis and hepatic de novo lipogenesis were evaluated after 4 days. RESULTS: Total energy expenditure was significantly lower in patients receiving n-3 fatty acids (0.015+/-0.001 vs. 0.019+/-0.001 kcal/kg/min with soy bean lipids (P<0.05)). Glucose oxidation, lipid oxidation, glucose production, gluconeogenesis, hepatic de novo lipogenesis, plasma glucose, insulin and glucagon concentrations did not differ (all P>0.05) in the 2 groups. CONCLUSIONS: n-3 fatty acids were well tolerated in this group of severely ill patients. They decreased total energy expenditure without adverse metabolic effects.

[R74W;R1070W;D1270N]: a new complex allele responsible for cystic fibrosis.

Since the beginning of population screening for CF carriers, it has become apparent that complex CFTR alleles are not uncommon. Deciphering their impact in disease pathogenesis remains a challenge for both clinicians and researchers. We report the observation of a new complex allele p.[R74W+R1070W+D1270N] found in trans with a type 1 mutation and associated with clinical diagnosis of cystic fibrosis in a one year-old Moroccan patient. This case underlines the difficulties in counseling patients with uncommon mutations and the necessity of functional studies to evaluate the structure-function relationships, since the association of several variations in cis can dramatically alter CFTR function.

Secretory IgA's complex roles in immunity and mucosal homeostasis in the gut.

Secretory IgA (SIgA) serves as the first line of defense in protecting the intestinal epithelium from enteric toxins and pathogenic microorganisms. Through a process known as immune exclusion, SIgA promotes the clearance of antigens and pathogenic microorganisms from the intestinal lumen by blocking their access to epithelial receptors, entrapping them in mucus, and facilitating their removal by peristaltic and mucociliary activities. In addition, SIgA functions in mucosal immunity and intestinal homeostasis through mechanisms that have only recently been revealed. In just the past several years, SIgA has been identified as having the capacity to directly quench bacterial virulence factors, influence composition of the intestinal microbiota by Fab-dependent and Fab-independent mechanisms, promote retro-transport of antigens across the intestinal epithelium to dendritic cell subsets in gut-associated lymphoid tissue, and, finally, to downregulate proinflammatory responses normally associated with the uptake of highly pathogenic bacteria and potentially allergenic antigens. This review summarizes the intrinsic biological activities now associated with SIgA and their relationships with immunity and intestinal homeostasis.