Quantitative trait locus on 15q for a metabolic syndrome variable derived from factor analysis

The metabolic syndrome represents a cluster of cardiovascular risk factors co-occurring in the same individual. The aim of this study was to identify chromosomal regions encoding genes predisposing to the metabolic syndrome using composite factors derived from maximum likelihood-based factor analysis. Genetic data were obtained from the Quebec Family Study and included 707 subjects from 264 nuclear families. Factor analyses were performed on eight metabolic syndrome-related phenotypes including waist circumference; BMI; systolic and diastolic blood pressure; and plasma insulin, glucose, triglyceride, and high-density lipoprotein-cholesterol levels. Three factors were identified and interpreted as general metabolic syndrome, blood pressure, and blood lipids, respectively. The general metabolic syndrome factor had high factor loadings (>0.4) for all phenotypes and explained 42% of the total variance, and family membership accounted for 45.6% of the factor variance. A genome-wide linkage scan performed with this first factor revealed the existence of a quantitative trait locus on chromosome 15 (86 cM) with a logarithm of odds score of 3.15. Suggestive evidence of linkage (logarithm of odds > 1.75) was also observed on chromosomes 1p, 3p, 3q, 6q, 7p, 19q, and 21q. These quantitative trait loci may harbor genes contributing to the clustering of the metabolic syndrome-related phenotypes.     

Biomechanical influence of disk properties on the load transfer of healthy and degenerated disks using a poroelastic finite element model

Spine degeneration is a pathology that will affect 80% of the population. Since the intervertebral disks play an important role in transmitting loads through the spine, the aim of this study was to evaluate the biomechanical impact of disk properties on the load carried by healthy (Thompson grade I) and degenerated (Thompson grades III and IV) disks. A three-dimensional parametric poroelastic finite element model of the L4/L5 motion segment was developed. Grade I, grade II, and grade IV disks were modeled by altering the biomechanical properties of both the annulus and nucleus. Models were validated using published creep experiments, in which a constant compressive axial stress of 0.35 MPa was applied for 4 h. Pore pressure (PP) and effective stress (S(E)) were analyzed as a function of time following loading application (1 min, 5 min, 45 min, 125 min, and 245 min) and discal region along the midsagittal profile for each disk grade. A design of experiments was further implemented to analyze the influence of six disk parameters (disk height (H), fiber proportion (%F), drained Young's modulus (E(a),E(n)), and initial permeability (k(a),k(n)) of both the annulus and nucleus) on load-sharing for disk grades I and IV. Simulations of grade I, grade III, and grade IV disks agreed well with the available published experimental data. Disk height (H) had a significant influence (p<0.05) on the PP and S(E) during the entire loading history for both healthy and degenerated disk models. Young's modulus of the annulus (E(a)) significantly affected not only S(E) in the annular region for both disk grades in the initial creep response but also S(E) in the nucleus zone for degenerated disks with further creep response. The nucleus and annulus permeabilities had a significant influence on the PP distribution for both disk grades, but this effect occurred at earlier stages of loading for degenerated than for healthy disk models. This is the first study that investigates the biomechanical influence of both geometrical and material disk properties on the load transfer of healthy and degenerated disks. Disk height is a significant parameter for both healthy and degenerated disks during the entire loading. Changes in the annulus stiffness, as well as in the annulus and nucleus permeability, control load-sharing in different ways for healthy and degenerated disks.     

The autoradiographic test for unscheduled DNA synthesis: a sensitive assay for the detection of DNA repair in the HepG2 cell line

We assessed the DNA-repair capacity of HepG2 cells, which were derived from a human hepatoma, by the unscheduled DNA synthesis assay, using the autoradiography protocol (UDS-AR). We evaluated DNA repair following exposure to direct mutagens (4-nitroquinoline-N-oxide (4-NQO), methyl methanesulfonate (MMS)), to mutagens requiring metabolic activation (benzo[a]pyrene (B[a]P), 2-acetylaminofluorene (2-AAF), N-dimethylnitrosoamine (NDMA)) or to structurally related non-mutagens such as pyrene and 4-acetylaminofluorene (4-AAF). All positive compounds tested induced UDS in HepG2 cells. With 4-NQO and MMS, a concentration-dependent increase in net nuclear grains per cell was observed, with 73 and 90% of cells, respectively, in repair at the highest concentration. B[a]P, 2-AAF and NDMA displayed similar dose-dependent UDS responses, but the percentage of cells in repair was lower (about 45%) than that for 4-NQO and MMS. We assessed the genotoxicity of the compounds tested by determining IC(5NNG): the concentration required to induce 5NNG. The compounds studied were ranked in order of IC(5NNG) as follows: 4-NQO = B[a]P > 2-AAF > MMS > NDMA. The UDS assay discriminated between mutagens and non-mutagens, as pyrene and 4-AAF failed to induce DNA repair. The present study demonstrates that UDS can be used as an endpoint for the detection of DNA damage in HepG2 cells.     

A missense mutation (R565W) in cirhin (FLJ14728) in North American Indian childhood cirrhosis

North American Indian childhood cirrhosis (CIRH1A, or NAIC), a severe autosomal recessive intrahepatic cholestasis described in Ojibway-Cree children from northwestern Quebec, is one of several familial cholestases with unknown molecular etiology. It typically presents with transient neonatal jaundice, in a child who is otherwise healthy, and progresses to biliary cirrhosis and portal hypertension. Clinical and physiological investigations have not revealed the underlying cause of the disease. Currently, liver transplantation is the only effective therapy for patients with advanced disease. We previously identified the NAIC locus by homozygosity mapping to chromosome 16q22. Here we report that an exon 15 mutation in gene FLJ14728 (alias Cirhin) causes NAIC: c.1741C-->T in GenBank cDNA sequence NM_032830, found in all NAIC chromosomes, changes the conserved arginine 565 codon to a tryptophan, altering the predicted secondary structure of the protein. Cirhin is preferentially expressed in embryonic liver, is predicted to localize to mitochondria, and contains WD repeats, which are structural motifs frequently associated with molecular scaffolds.     

Role of IFN-gamma and IL-2 in rat lung epithelial cell migration and apoptosis after oxidant injury

In the present study, IFN-gamma exposure to primary cultures of rat type II epithelial cells (TIIP) upregulated membrane expression of the common gamma-chain of the IL-2 receptor (approximately 2.5- to 4-fold increase) and redistributed receptor affinity in TIIP, as assessed by Western blot, cell, and tissue histochemistry and Scatchard analysis. As for restitution processes of the lung epithelium, functionality of IL-2R on TIIP was conditional to IFN-gamma exposure: 1) IFN-gamma priming promoted a fivefold increase of IL-2-driven TIIP locomotion (P < 0.05 vs. control at 100 U/ml) and 2) IFN-gamma coincubation with IL-2 reduced bleomycin-induced TIIP apoptosis in vitro by 25% (caspase-3 activity) and by approximately 70% (TdT-mediated dUTP nick end labeling/4',6'-diamidino-2-phenylindole assay) as well as in vivo by approximately 90% (caspase-3 activity; P < 0.05 vs. control). Sustained p42/44 extracellular signal-regulated kinase activity played a protective role in this process, whereas specific inhibition by PD-98059 (50 microM) significantly reversed bleomycin-induced TIIP apoptosis (P < 0.05 vs. control). From these in vitro and in vivo data, it is proposed that combinations of IFN-gamma and IL-2 can drive repair activity of TIIP by stimulating migration and preventing programmed cell death, both of which are speculated to be very fast restitution events after oxidant-induced acute lung injury.     

Genome-wide linkage scan reveals multiple susceptibility loci influencing lipid and lipoprotein levels in the Quebec Family Study

A genome-wide linkage study was performed to identify chromosomal regions harboring genes influencing lipid and lipoprotein levels. Linkage analyses were conducted for four quantitative lipoprotein/lipid traits, i.e., total cholesterol, triglyceride, HDL-cholesterol (HDL-C), and LDL-C concentrations, in 930 subjects enrolled in the Québec Family Study. A maximum of 534 pairs of siblings from 292 nuclear families were available. Linkage was tested using both allele-sharing and variance-component linkage methods. The strongest evidence of linkage was found on chromosome 12q14.1 at marker D12S334 for HDL-C, with a logarithm of the odds (LOD) score of 4.06. Chromosomal regions harboring quantitative trait loci (QTLs) for LDL-C included 1q43 (LOD = 2.50), 11q23.2 (LOD = 3.22), 15q26.1 (LOD = 3.11), and 19q13.32 (LOD = 3.59). In the case of triglycerides, three markers located on 2p14, 11p13, and 11q24.1 provided suggestive evidence of linkage (LOD > 1.75). Tests for total cholesterol levels yielded significant evidence of linkage at 15q26.1 and 18q22.3 with the allele-sharing linkage method, but the results were nonsignificant with the variance-component method. In conclusion, this genome scan provides evidence for several QTLs influencing lipid and lipoprotein levels. Promising candidate genes were located in the vicinity of the genomic regions showing evidence of linkage.     

Polymorphism in exon 4 of the human 3 beta-hydroxysteroid dehydrogenase type I gene (HSD3B1) and blood pressure

There is growing evidence to the effect that steroid hormones are associated with a complex phenotype of metabolic abnormalities usually referred to as the metabolic syndrome. The 3 beta-hydroxysteroid dehydrogenases/Delta(4,5)-isomerase (3 beta-HSD) is crucial to the biosynthesis of hormonal steroids, including aldosterone, cortisol, and testosterone. The objective of the present study was to examine the potential impact of a T-->C substitution at codon Leu(338) of the type I (HSD3B1) 3 beta-HSD gene on obesity, circulating hormones, and estimates of insulin, glucose, and lipid metabolism as well as blood pressure in 284 unrelated Swedish men born in 1944. The subjects were genotyped by using PCR amplification of exon 4 of the HSD3B1 gene followed by digestion with the restriction enzyme BglII. The frequency of allele T was 0.44 and that of allele C 0.56. Homozygotes for the C allele (n=75) had significantly (P<0.05) higher mean systolic and diastolic blood pressures compared to both heterozygotes (n=143) and homozygotes for the T allele (n=45). In addition, the C allele was significantly (P=0.018) more frequent among subjects with grade 1 hypertension (>140/90 mm Hg) compared to normotensive (<130/85 mm Hg) subjects. These results were all adjusted for the potential confounding effect of body mass index (BMI) and waist-to-hip ratio (WHR). Other measurements such as BMI, WHR, abdominal sagittal diameter, salivary cortisol, total testosterone, serum leptin, fasting insulin and glucose, and serum lipids were not different across the HSD3B1 genotype groups. In conclusion, a T-->C polymorphism at codon Leu(338) of exon 4 of the HSD3B1 gene is associated with elevated systolic and diastolic blood pressures. The pathogenic mechanism underlying this association is, however, uncertain from the present data and further studies are warranted.     

Vacuuming tarnished plant bug on strawberry: a bench study of operational parameters versus insect behavior

A vacuum apparatus was used in a test bench environment to determine the effects of two operational parameters on vacuuming efficacy for an insect pest. Nymphs and adults of tarnished plant bug, Lygus lineolarisP. de. B. (Hemiptera: Miridae), marked with fluorescent powder, were positioned on strawberry plants according to three height classes. Three speeds of inlet passage (i.e., 2, 4 and 6 km h^–1) and two heights (passage at 2/3 and 3/3 of the canopy) of inlet relative to the top canopy of the plants were investigated. After vacuuming the marked insects remaining on the plants were then found using a UV light and the class height of their position on the plant and the substrate (i.e., soil, leaf, stem or fruit/flower) were noted. The efficacy of the vacuum was optimal when the inlet was passed at 4 km h^–1with the inlet at a height of 2/3 of the strawberry canopy. Nymphs were usually vacuumed more efficiently than adults. Most (64.5%) individuals that were not vacuumed did not change position after inlet passage. Most (85.9%) individuals that changed position after inlet passage experienced vertical, mostly downward, movements.