The immunobiology of T cell responses to Mls-locus-disparate stimulator cells. II. Effects of Mls-locus-disparate stimulator cells on cloned, protein antigen-specific, Ia-restricted T cell lines

Cloned, protein antigen-specific, Ia-restricted T cell lines frequently (approximately 20%) also respond strongly to stimulator cells from strains expressing stimulatory alleles at the chromosome 1-encoded Mls-locus. Furthermore, such responses are blocked by monoclonal antibodies specific for Ia antigens expressed by the stimulator rather than the responder cells. However, such responses show no specificity for polymorphic determinants on Ia molecules, although in such responses, as in primary and secondary T cell responses to stimulating Mls-locus alleles, I-E molecules appear to play a central role. These results, combined with the unique immunobiology of the primary T cell proliferative response to Mls-locus-disparate stimulator cells, suggest to us that this response involves the interaction of the receptor on T cells for antigen:self Ia with a relatively nonpolymorphic region of Ia glycoproteins. This hypothesis is supported by the observation that a monoclonal antibody to the T cell receptor will inhibit both responses, although the response to Mls-locus-disparate stimulators appears to be more sensitive to these antibodies. We propose that the interaction of the T cell receptor with Ia is stabilized by a cell interaction molecule encoded or regulated by the Mls-locus gene product permitting the T cell receptor:Ia glycoprotein interaction to lead to T cell activation.     

Cross-linking of DNA in liver and testes of rats fed 1,3-propanediol

1,3-Propanediol (PAD) was fed to rats for 15 weeks, and its effects on hepatic and testicular DNA were studied. The control rats were fed a casein-based diet that contained 10% tocopherol-stripped corn oil with 30 IU of d,l-α-tocopherol acetate/kg; the experimental rats were fed the same diet with 500 ppm of PAD. Homogenates prepared from the livers of each group of rats converted 1,3-propanediol to malondialdehyde (MDA) with equal efficacy, but homogenates of testes did not catalyze this conversion. After 10–15 weeks of feeding the diets, the hepatic DNA of the rats fed PAD had less template activity, more bound tryptophan and more DNA-protein and interstrand DNA cross-links than that of the control rats. As measured by template activity and bound tryptophan, testicular DNA of the experimental rats was not different from that of the control rats; however, there was slightly more cross-linking in the testicular DNA of experimental rats than in that of control rats. Testes of the experimental rats contained more lipid-soluble fluorophores than did those of the control rats. The results are consistent with the conclusion that PAD was converted to MDA in vivo and that MDA is the reactive species that caused the observed biological damage.     

Recognition of influenza virus hemagglutinin by subtype-specific and cross-reactive proliferative T cells: contribution of HA1 and HA2 polypeptide chains

The recognition of influenza virus hemagglutinin (HA) by T lymphocytes was examined by assaying the T cell proliferative response of influenza virus-primed T cells to purified HA of different influenza A subtypes or to isolated heavy (HA1) or light (HA2) polypeptide chains of the HA molecule. The proliferative response to HA was dependent on the activation of an Ly-1+2- subset of T cells and required the presence of nylon wool-adherent, radiation-resistant accessory cells. T cells from mice primed by infection with one strain of type A influenza virus cross-reacted with other purified HA not only of the same subtype as the priming virus but also of serologically distinct subtypes of influenza A (but not B) virus. The response of virus-primed T cells to the homologous HA or to HA of the same subtype was shown to involve recognition of determinants on both the HA1 and the HA2 chains. The recognition of HA of different subtype by cross-reactive T cells appeared to be directed predominantly to determinants on HA2. Because the antibody response to influenza virus HA is not cross-reactive between subtypes and is directed predominantly to determinants on HA1, the present results indicate that at least some of the determinants on HA recognized by T cells are different from those recognized by B cells and that the HA2 chain may be involved primarily in stimulation of T cell rather than B cell immunity.     

Can transposable element copy number distribution parameters be estimated from natural populations of Drosophila melanogaster?

The copy frequency distribution of a transposable element family in a Drosophila melanogaster natural population is generally characterised by the values of the Charlesworths' model parameters α and β (Charlesworth & Charlesworth, 1983). The estimation of these parameters is made using the observed distribution of the occupied sites in a population sample. Several results have been interpreted as due either to the influence of stochastic factors or to deterministic factors (transposition, excision, selection…). The accuracy of this method was tested by estimations performed on samples from simulated populations. The results show that with the sample size usually used for natural population studies, the confidence intervals are too large to reasonably deduce either the element copy number distribution or the values of transposition and excision rate and selective coefficients.     

A note on antibiotic-resistant Escherichia coli in adult man, raw sewage and sewage-polluted River Tigris in Mosul, Nineva

A total of 600 isolates of Escherichia coli were isolated, over a 9 month period during 1984, from healthy human adults, raw sewage and the sewage-polluted River Tigris in Nineva. Over 90% of these organisms were E. coli type 1, but only 8.3% could be serogrouped as enteropathogenic E. coli . Resistance of these organisms to 11 antimicrobial drugs was assessed. Over 40% were antibiotic-resistant and of these 77.1% were resistant to more than one antibiotic. The minimal inhibitory concentration of ampicillin for 193 selected strains from the various sources was determined and ranged from <0.625- > 160 μg/ml. The high incidence of antibiotic-resistant E. coli in this locality and the possible implications to human health are discussed.     

Neuromuscular, anaerobic, and aerobic performance characteristics of elite power athletes

Various aspects of neuromuscular, anaerobic, and aerobic performance capacity were investigated in four powerlifters, seven bodybuilders, and three wrestlers with a history of specific training for several years. The data (means +/- SD) showed that the three subject groups possessed similar values for maximal isometric force per unit bodyweight (50.7 +/- 9.6, 49.3 +/- 4.1, and 49.3 +/- 10.9 N/kg, respectively). However, significant (P less than 0.05) differences were observed in the times for isometric force production, so that e.g., times to produce a 30% force level were shorter for the wrestlers and bodybuilders (28.3 +/- 3.1 and 26.4 +/- 6.6 ms) than that (53.3 +/- 23.7 ms) for the powerlifters. Utilization of elastic energy by the wrestlers was significantly (P less than 0.05) better than that of the other two subject groups, as judged from differences between the counter-movement and squat jumps at 0, 40, and 100 kg's loads. No differences were observed between the groups in anaerobic power in a 1-min maximal test, but the values for VO2 max were higher (P less than 0.05) among the wrestlers and bodybuilders (57.8 +/- 6.6 and 50.8 +/- 6.8 ml X kg-1 X min-1) as compared to the powerlifters (41.9 +/- 7.2 ml X kg-1 X min-1). Within the limitations of the subject sample, no differences of a statistical significancy were observed between the groups in fibre distribution, fibre areas, or the area ratio of fast (FT) and slow (ST) twitch fibres in vastus lateralis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Testing for Validity and Reliability in Cross-Cultural Research

A set of procedures is offered for assessing interraler reliability and certain aspects of validity of codes in cross-cultural studies. The method assumes that at least two independent raters have coded more than one trait. Each trait coded by one rater is correlated with each trait coded by a second, and all the codings by a single rater are intercorrelated with each other. The results are presented in a multitrait-multi-rater matrix. From this matrix it is possible to determine the interrater reliability and discriminant validity of trails in addition to a higher order concept based on pairs of traits.