Social contact,social attitudes,and twin similarity

The nature of the relationship between social contact and attitude similarity between twins was investigated using longitudinal data from a sample of Australian twins. Earlier research has suggested that social attitudes are not explained solely by shared environment; rather there are both genetic and environmental components that explain variance in social attitudes. Using three types of analyses we investigated the magnitude of the relationship and the direction of causation between attitude similarity and social contact. Longitudinal analysis of within-pair variance by level of contact suggests that attitude similarity leads to contact among the females and that similarity is both genetically and environmentally based. Analyses using a crosslag regression model suggest that similarity causes contact among MZ females. Biometrical analyses indicate differences in direction of causation for males and females. Among females, both genetic and shared environmental parameter estimates could be equated across contact groups, suggesting little relationship between contact and similarity. Among males, findings of smaller estimated heritability in the high-contact group suggest that similarity causes contact. However, an increased estimate of the contribution of shared environmental variance in the high-contact males could additionally suggest that contact leads to similarity.     

Interaction between the amino and carbonyl groups in copoly(2-dimethylaminoethyl methacrylate/N-phenylmaleimide)

Interactions between the carbonyl and amino groups in copolymers of 2-dimethylaminoethyl methacrylate with N-phenylmaleimide are reported. The existence of interactions ensues from potentiometric measurements and UV-VIS spectra. Interactions in these copolymers result in the formation of energetically very advantageous chromophores, reflected in an intense red colour of the substances obtained.     

Defective peroxisomal catabolism of branched fatty acyl coenzyme A in mice lacking the sterol carrier protein-2/sterol carrier protein-x gene function

Gene targeting in mice was used to investigate the unknown function of Scp2, encoding sterol carrier protein-2 (SCP2; a peroxisomal lipid carrier) and sterol carrier protein-x (SCPx; a fusion protein between SCP2 and a peroxisomal thiolase). Complete deficiency of SCP2 and SCPx was associated with marked alterations in gene expression, peroxisome proliferation, hypolipidemia, impaired body weight control, and neuropathy. Along with these abnormalities, catabolism of methyl-branched fatty acyl CoAs was impaired. The defect became evident from up to 10-fold accumulation of the tetramethyl-branched fatty acid phytanic acid in Scp2(−/−) mice. Further characterization supported that the gene disruption led to inefficient import of phytanoyl-CoA into peroxisomes and to defective thiolytic cleavage of 3-ketopristanoyl-CoA. These results corresponded to high-affinity binding of phytanoyl-CoA to the recombinant rat SCP2 protein, as well as high 3-ketopristanoyl-CoA thiolase activity of the recombinant rat SCPx protein.     

Meiotic defects in a man with non-obstructive azoospermia: case report

Infertile men have an increased frequency of aneuploid sperm. We have determined that decreased recombination is associated with the production of aneuploid sperm in humans. The aim of this study was to determine whether some cases of infertility are associated with decreased meiotic recombination. Analysis of the early stages of meiosis was performed in a 33-year-old man with non-obstructive azoospermia. Newly developed immunocytogenetic techniques were used to identify the synaptonemal complex (SC) in various stages of prophase. Antibodies to meiotic proteins identified the SC (SYN1/SCP3), the centromere (CREST) and recombination sites (MLH1). Only 36 meiotic spreads were recovered from the infertile man, compared with hundreds available from controls. One-third of the cells were in zygotene compared with 4% in controls, demonstrating an inability of bivalents to synapse and progress to pachytene. The infertile man had a greatly reduced frequency of recombination, with a mean of only 32.7 MLH1 foci/cell (range 1-60) compared with 46.0 (range 21-62) in control donors. A high proportion of cells (73%) contained at least one autosomal bivalent with zero MLH1 foci, compared with only 4.5% in control donors. Discontinuities in the SC were also more prevalent (68% of cells versus 26% in controls). This is the first demonstration of dramatic pachytene-stage abnormalities in an infertile man using these powerful new immunocytogenetic techniques.     

Two unique patients with trisomy 18 mosaicism and molecular marker studies

We report two unusual patients with trisomy 18 mosaicism presenting with minor anomalies and failure to thrive in the first year of life. Chromosome analysis showed trisomy 18 in 30/30 peripheral blood lymphocytes in both children. Analysis of skin fibroblasts in the first child showed normal female chromosomes in 30/30 cells, and the fibroblast karyotype in the second child showed mosaicism for tetrasomy 18p, trisomy 18, and normal female chromosomes (karyotype 47,XX, +i(18)(p10)[47]/47,XX, +18[9] /46,XX[4]). Trisomy 18 commonly results from nondisjunction at maternal meiosis II (MII). Nondisjunction at maternal MII has also been postulated to be the initial step in the formation of tetrasomy 18p. In our second case, the additional chromosome 18 was the result of maternal nondisjunction at MII, consistent with this hypothesis. In the first case, nondisjunction at maternal meiosis I (MI) was responsible for the extra chromosome 18.     

Protection against virulent Mycobacterium avium infection following DNA vaccination with the 35-kilodalton antigen is accompanied by induction of gamma interferon-secreting CD4(+) T cells

Mycobacterium avium is an opportunistic pathogen that primarily infects immunocompromised individuals, although the frequency of M. avium infection is also increasing in the immunocompetent population. The antigen repertoire of M. avium varies from that of Mycobacterium tuberculosis, with the immunodominant 35-kDa protein being present in M. avium and Mycobacterium leprae but not in members of the M. tuberculosis complex. Here we show that a DNA vector encoding this M. avium 35-kDa antigen (DNA-35) induces protective immunity against virulent M. avium infection, and this protective effect persists over 14 weeks of infection. In C57BL/6 mice, DNA vaccines expressing the 35-kDa protein as a cytoplasmic or secreted protein, both induced strong T-cell gamma interferon (IFN-gamma) and humoral immune responses. Furthermore, the antibody response was to conformational determinants, confirming that the vector-encoded protein had adopted the native conformation. DNA-35 immunization resulted in an increased activated/memory CD4(+) T-cell response, with an accumulation of CD4(+) CD44(hi) CD45RB(lo) T cells and an increase in antigen-specific IFN-gamma production. The protective effect of the DNA-35 vectors against M. avium infection was comparable to that of vaccination with Mycobacterium bovis BCG and significantly greater than that for previous treated infection with M. avium. These results illustrate the importance of the 35-kDa protein in the protective response to M. avium infection and indicate that DNA vaccination successfully promotes a sustained level of protection during chronic M. avium infection.     

A Negative Slow Wave Related to Conceptual Load Which Vanishes if the Amount of Load is Increased? A Reply to Ruchkin and Johnson

Ruchkin and Johnson (1991) claim that the mode of responding used by Rösler & Heil (1991) may have camouflaged effects of a negative slow wave that Ruckin et al. (1988) had found to be related to the difficulty of mental calculation problems. This criticism is addressed by three arguments which support the interpretation of Rösler and Heil (1991). According to this view, the negative slow wave in question is more likely related to unspecific processing factors, such as effort and event expectation, than to specific processing demands such as these induced by mental arithmetic.     

Mutation analysis of the nerve specific promoter of the peripheral myelin protein 22 gene in CMT1 disease and HNPP.

We analysed the nerve specific promoter of the peripheral myelin protein 22 gene (PMP22) in a set of 15 unrelated patients with Charcot-Marie-Tooth type 1 disease (CMT1) and 16 unrelated patients with hereditary neuropathy with liability to pressure palsies (HNPP). In these patients no duplication/deletion nor a mutation in the coding region of the CMT1/ HNPP genes was detected. In one autosomal dominant CMT1 patient, we identified a base change in the non-coding exon 1A of PMP22 which, however, did not cosegregate with the disease in the family. This study indicates that mutations in the nerve specific PMP22 promoter and 5' untranslated exon will not be a common genetic cause of CMT1A and HNPP.     

In situ characterization of T lymphocyte subpopulations in leprosy in the mangabey monkey.

Leprosy in the mangabey monkey is an experimental model which is similar both clinically and histologically to human lepromatous leprosy. The immunopathology of these diseases was compared using monoclonal antibodies against T lymphocyte subpopulations in frozen tissue sections with an immunoperoxidase technique. In both mangabey and human lepromatous granulomas OKT4 (or Leu 3a) and Leu 2a cells were scattered among macrophages with greater numbers of Leu 2a as compared with OKT4 (or Leu 3a) cells. The results suggest that from an immunopathological standpoint experimental leprosy in mangabeys will provide a suitable model for the investigation of the pathogenesis of human lepromatous leprosy and for the evaluation of new antileprosy vaccines.