No association between the Pro197Leu polymorphism in the glutathione peroxidase (GPX1) gene and schizophrenia

OBJECTIVE: Oxidative stress such as free radical-mediated neuronal dysfunction may be involved in the pathophysiology of schizophrenia. The human glutathione peroxidase (GPX1) is a selenium-dependent enzyme, which plays an important role in the detoxification of free radicals. We therefore hypothesized that the GPX1 gene, which is located on chromosome 3p21.3, may be involved in the pathophysiology of schizophrenia. The aim of this study is to examine whether a potentially functional polymorphism, a proline (Pro) to leucine (Leu) substitution at codon 197 (Pro197Leu) of the human GPX1 gene, is associated with susceptibility to schizophrenia. METHODS: We genotyped the Pro197Leu polymorphism in a total of 113 nuclear families that had a proband with schizophrenia. Genetic association was tested using the transmission disequilibrium test (TDT), the sib transmission disequilibrium test (STDT), and the family-based association test (FBAT). RESULTS: The minor allele (Leu) frequency was calculated to be 0.282. We could not find significant transmission disequilibrium of the alleles for the Pro197Leu polymorphism in the GPX1 gene in association with the presence of schizophrenia in our family sample (TDT, chi2=0.03, degrees of freedom=1, P=0.86; combined TDT-STDT, Z'=-0.052, P=0.47; FBAT, Z=0.000, P=1.000). CONCLUSION: The results of this study suggest that the GPX1 polymorphism is unlikely to be associated with susceptibility to schizophrenia.     

Molecular Characterization of Vancomycin-Resistant Enterococci from Hospitalized Patients and Poultry Products in The Netherlands

Vancomycin-resistant enterococci (VRE) pose an emerging health risk, but little is known about the precise epidemiology of the genes coding for vancomycin resistance. To determine whether the bacterial flora of consumer poultry serves as a gene reservoir, the level of contamination of poultry products with VRE was determined. VRE were genotyped by pulsed-field gel electrophoresis (PFGE), and transposon structure mapping was done by PCR. The vanX-vanY intergenic regions of several strains were further analyzed by sequencing. A total of 242 of 305 (79%) poultry products were found to be contaminated with VRE. Of these VRE, 142 (59%) were high-level-vancomycin-resistant Enterococcus faecium strains (VREF). PFGE revealed extensive VREF heterogeneity. Two genotypes were found nationwide on multiple occasions: type A (22 of 142 VREF [15%]) and type B (14 of 142 VREF [10%]). No PFGE-deduced genetic overlap was found when VREF from humans were compared with VREF from poultry. Two vanA transposon types were identified among poultry strains. In 59 of 142 (42%) of the poultry VREF, the size of the intergenic region between vanX and vanY was ~1,300 bp. This transposon type was not found in human VREF. In contrast, all human strains and 83 of 142 (58%) of the poultry VREF contained an intergenic region 543 bp in size. Sequencing of this 543-bp intergenic vanX-vanY region demonstrated full sequence conservation. Though preliminary, these data suggest that dissemination of the resistance genes carried on transposable elements may be of greater importance than clonal dissemination of resistant strains. This observation is important for developing strategies to control the spread of glycopeptide resistance.     

Structure of four amplified DNA novel joints

The structures of four novel joints present in the amplified DNA of a Syrian hamster cell line highly resistant to N-(phosphonacetyl)-l-aspartate were analyzed. Novel joints J1, J2, and J4 were formed by recombination between two regions of wild-type DNA, whereas joint J3 is the end point of an inverted duplication. A fraction of the J3 copies displays a cruciform structure in the purified genomic DNA. The formation of J1 and J2 apparently involved a simple breakage and joining of the two wild-type sequences, whereas extra nucleotides are present at the junction point of J3 and J4. The two regions of the wild-type DNA which have recombined to form J1, J2, and J4 show few sequence similarities, indicating that these joints probably resulted from nonhomologous recombination. AT-rich regions are present in the vicinity of the breakpoint for the four joints and eight of 10 crossover points could be associated with putative topoisomerase I cleavage sites. Our results indicate that different types of novel joints are present in the amplified DNA of this cell line, which was isolated after several steps of selection.     

Solid-phase enzyme immunoassay or radioimmunoassay for the detection of immune complexes based on their recognition by conglutinin: conglutinin-binding test. A comparative study with 125I-labelled C1q binding and Raji-cell RIA tests

Bovine conglutinin was used in a solid-phase assay for the detection of immune complexes. In a first step, the tested serum sample is incubated in polypropylene tubes coated with conglutinin to allow C3-coated immune complexes to bind to solid-phase conglutinin. In a second step, the conglutinin-bound complexes are detected using an enzyme-conjugated or radiolabelled anti-immunoglobulin antibody.

The conglutinin-binding (KgB) test does not suffer from the interference of DNA, heparin or endotoxins. Its limit of sensitivity for aggregated IgG is 3 μg/ml undiluted human serum. Immune complexes prepared in vitro using tetanus toxoid, or DNA, and corresponding antibodies in human sera could be detected at various antigen/antibody ratios and at antibody concentrations lower than 8 μg/ml. The KgB test allowed for the detection of immune complexes in sera from patients with systemic lupus erythematosus, rheumatoid arthritis, idiopathic vasculitis, leprosy and leukemia. These sera were also tested using the ¹²⁵I-labelled Clq-binding activity (BA) test and the KgB test simultaneously, and a significant rank order correlation was observed. In patients with leukemia, a significant correlation was observed using three tests, KgB, ¹²⁵I-labelled Clq BA and Raji-cell radioimmunoassay (RIA).

Therefore, the KgB test appears as a simple and reproducible method, utilizing a very stable reagent, with a sensitivity and specificity comparable to the other tests studied and allowing for clinical application.

     

Molecular cloning and characterization of actin genes from Echinococcus granulosus

An Echinococcus granulosus genomic library has been screened with a mouse β-actin cDNA probe. Two clones carrying DNA fragments of about 15 kb, possibly derived from the same genome region, have been isolated. This 15-kb genomic region includes 2 actin-related sequences (EgactI and EgactII) separated by about 4 kb. The nucleotide sequences of both genes were determined. The EgactI sequence presents no introns, but an intron of 591 bp was observed in the EgactII sequence. The genes potentially encode 375 and 376 amino-acid-long actins, respectively, with a homology of 85.3%. The deduced amino acid sequences from both genes were compared to the actin sequences from other organisms, showing similarities ranging from 63.5% to 90.6%. The nucleotide sequence of a partial actin cDNA clone has been determined. The deduced amino acids sequence showed a homology of 90.3% and 88.0% in relation to the EgactI and EgactII sequences respectively, suggesting the existence of at least one more actin gene in E. granulosus. This hypothesis is reinforced by the number of bands detected in the Southern blot analysis. Experiments based on the amplification of DNA segments using 3′-specific actin primers indicate that the EgactI gene is transcribed in protoscoleces.     

Hydrophobic IgG-containing immune complexes in the plasma of autoimmune MRL/lpr mice, lactate dehydrogenase-elevating virus-infected mice, and pigs: association with transforming growth factor-beta and pH-dependent amplification

Persistent infection of mice with lactate dehydrogenase-elevating virus (LDV) is associated with polyclonal B cell activation, autoimmunity, and circulating hydrophobic IgG-containing immune complexes (ICs), which bind to the surfaces of uncoated ELISA plates in the presence of 0.05% Tween 20. We demonstrate here that hydrophobic IgG-containing ICs also appear naturally in the plasma of autoimmune MRL/lpr mice. These and the similar hydrophobic ICs of LDV-infected mice as well as pigs coincide on ELISA plate surfaces with TGF-beta, apparently in the form of an IgG-TGF-beta complex. Circulating hydrophobic IgG-containing ICs are also susceptible to considerable amplification in vitro by exposure to alkaline conditions. By this latter method, the fraction of in vivo hydrophobic IgG, relative to the maximum in vitro chemically inducible IgG, was found to be about 20% in the plasma of LDV-infected mice, 5% in normal mouse plasma, and less than about 2% in pig plasma. These results indicate the potential for both chemically induced and protein-binding contributions to the generation of hydrophobic IgG-containing molecules, and have implications for immunopathological mechanisms in autoimmunity and persistent virus infections.