Reliability of the acetabular teardrop as a landmark

Summary This study investigated the effect of tilt and observer reliability on radiographic measurements of the position of a prosthetic acetabular cup in seven dry bone pelves using the teardrop as a landmark. Coronal or sagittal tilt of more than five degrees was easily recognisable and there was effectively no observer variation in the measurements up to this limit. In addition, 90 out of 100 randomly selected antero-posterior pelvic radiographs from an outpatient department were not significantly rotated and 93 demonstrated a clearly defined teardrop. Measurements about the teardrop on routine radiographs are therefore sufficiently accurate to allow assessment of prosthetic position.

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La valeur du sourcil cotyloidien comme repère d'analyse radiologique

Résumé Cette étude, conduite sur 7 bassins secs, apprécie l'effet de l'inclinaison du bassin sur la qualité de l'analyse radiographique de la position d'une cupule prothétique de hanche en utilisant le sourcil cotyloïdien comme repère. Une inclinaison du bassin dans les plans coronal et sagittal est aisément détectable et il n'existe pas de variation d'analyse entre les différents observateurs en dessous de 5° d'inclinaison. De plus, sur 100 radiographies antéro-postérieures de bassin choisies au hasard dans les dossiers de consultation, 90 avaient été réalisées sans incidence particulièrement adaptée et l'on pouvait repérer facilement le sourcil sur 93% d'entre elles. Les mesures faites sur des radios de routine sont donc suffisamment précises pour permettre l'évaluation de la position d'une prothèse à partir du sourcil cotyloïdien.

     

Ascending aortic stenosis selectively increases action potential-induced Ca2+ influx in epicardial myocytes of the rat left ventricle

A decrease of the transient outward potassium current (Ito) has been observed in cardiac hypertrophy and contributes to the altered shape of the action potential (AP) of hypertrophied ventricular myocytes. Since the shape and duration of the ventricular AP are important determinants of the Ca2+ influx during the AP (QCa), we investigated the effect of ascending aortic stenosis (AS) on QCa in endo- and epicardial myocytes of the left ventricular free wall using the AP voltage-clamp technique. In sham-operated animals, QCa was significantly larger in endocardial compared to epicardial myocytes (803 +/- 65 fC pF(-1), n = 27 vs. 167 +/- 32 fC pF(-1), n = 38, P < 0.001). Ascending aortic stenosis significantly increased QCa in epicardial myocytes (368 +/- 54 fC pF(-1), n = 42, P < 0.05), but did not alter QCa in endocardial myocytes (696 +/- 65 fC pF(-1), n = 26). Peak and current-voltage relation of the AP-induced Ca2+ current were unaffected by AS. However, the time course of the current-voltage relation was significantly prolonged in epicardial myocytes of AS animals. Model calculations revealed that the increase in QCa can be ascribed to a prolonged opening of the activation gate, whereas an increase in inactivation prevents an excessive increase in QCa. In conclusion, AS significantly increased AP-induced Ca2+ influx in epicardial but not in endocardial myocytes of the rat left ventricle.     

Regulation of the antibody response to sheep erythrocytes by monoclonal IgG antibodies

Monoclonal antibodies directed against sheep erythrocytes of the isotypes IgG1, IgG2b and IgG2a were used to analyze the specificity of antibody-induced suppression of the immune response. It was first shown that all monoclonals reacted against different antigenic determinants and they all suppressed the immune response to sheep erythrocytes when given shortly after the antigen to more than 50% as compared to 90-96% inhibition obtained with a polyclonal antiserum. Increasing the doses of monoclonals did not increase suppression. However, two different monoclonals administered together caused an additive, but not a synergistic inhibitory effect. No enhancement of the immune response was observed with any of the Ig classes tested. These findings show that four different antigenic determinants on sheep erythrocytes induced the synthesis of corresponding antibodies, with little or no signs of a dominant determinant. Passively administered monoclonal antibodies, even at supraoptimal doses, never suppressed the immune response to the same extent as a polyclonal antiserum, suggesting that each monoclonal only suppressed the synthesis of the corresponding antibody and did not affect antibody synthesis to other determinants.     

DNA evidence of Borrelia lonestari in Amblyomma americanum (Acari: Ixodidae) in southeast Missouri

Amblyomma americanum collected near Lake Wappapello, Missouri, tested positive for Borrelia lonestari using polymerase chain reaction and sequence analyses of B. lonestari 16S rRNA and flagellin (flaB) genes. Twelve pools containing a total of 214 nymph or adult ticks contained evidence of infection with B. lonestari (minimum prevalence 5.6%). These data suggest that persons in southeast Missouri are at risk for exposure to B. lonestari after A. americanum tick bite, a possible cause of erythema migrans-like rash illness in this region. Derivation of the complete coding sequence for B. lonestari flaB is also reported.     

Experimental autoimmune myasthenia gravis in naive non-obese diabetic (NOD/LtJ) mice: susceptibility associated with natural IgG antibodies to the acetylcholine receptor

Naive non-obese diabetic (NOD/LtJ) mice spontaneously produce natural IgG autoantibodies against self-antigens associated with the experimental autoimmune diseases to which they are susceptible: insulin-dependant diabetes mellitus, systemic lupus erythematosus and experimental autoimmune encephalomyelitis. We discovered recently that NOD/LtJ mice also spontaneously produce IgG antibodies to the acetylcholine receptor (AchR), an antigen that can induce experimental autoimmune myasthenia gravis (EAMG) in susceptible rodents. However, there are no reports indicating that NOD/LtJ mice are susceptible to EAMG. To test whether the presence of spontaneous IgG autoantibodies can predict susceptibility to an autoimmune disease, we challenged NOD/LtJ mice using a standard protocol to induce EAMG. We now report that NOD/LtJ mice developed EAMG, although to a somewhat lesser degree than did C57BL/6 mice, a strain regarded as highly susceptible to the disease. Both strains produced comparable levels of immune antibodies to AchR of the complement-fixing isotypes IgG2a and IgG2b; however, NOD/LtJ mice produced significantly more IgG1. An antigen-specific T cell proliferative response to AchR of the same magnitude was detected in both strains, together with the secretion of similar amounts of IFN-gamma. Thus, NOD/LtJ mice are susceptible to EAMG and disease induction is accompanied by immune responses comparable to those seen in the susceptible strain C57BL/6. These results support the association between specific, natural IgG autoantibodies and susceptibility to the induction of a particular autoimmune disease.     

Adenosine and related nucleotides alter calcium uptake in depolarized synaptosomes of torpedo electric organ

Summary Calcium has been shown to enter cholinergic synaptosomes transiently during potassium-induced depolarization, in which ACh and ATP are released together. Because junctional ATP is rapidly hydrolyzed by extracellular ATPases, I studied and compared the roles of ATP, ADP, AMP, and adenosine (Ade) on the control of calcium uptake during depolarization.Pure cholinergic synaptosomes of Torpedo fish electric organ were depolarized by high potassium concentrations and the amount of calcium uptake was then measured in the presence of equal concentrations of Ade and its related nucleotides. Calcium uptake was more inhibited when the nucleotide was less phosphorylated. Thus, Ade was the greatest inhibitor.Because Ade is quickly and actively taken up from the extracellular medium by synaptosomes and converted intracellularly to ATP, I also measured the capacity of Ade, after its initial inhibitory action, to reactivate the calcium uptake. After a short preincubation with Ade, the later uptake of calcium was enhanced. The combined results support a complete role of adenosine and related nucleotides in the control of calcium movement across the presynaptic membrane.     

Self-esteem and causal attributions for success and failure in children

In a comparison of causal attributions following success and failure in hypothetical social, athletic, and academic situations, high self-esteem grade school children were more likely than low self-esteem children to attribute their success to ability and their failure to either lack of effort or bad luck. Low self-esteem children, on the other hand, attributed their success more often than high self-esteem children to good luck (and in social situations to effort and task ease as well) and their failure to lack of ability. Whereas prior studies that focused only on the internal-external dimension found that low and high self-esteem children differed in their attributional style to success but not to failure, the present study found that when distinctions between behavioral and characterological attributions (stability and globality dimensions) were included, the two groups differed significantly in response to both success and failure. Although perhaps not generalizable beyond the present attribution measure, the most pronounced attribution differences between low and high self-esteem children were observed in the social domain, the least in the academic domain, with athletics falling in between. Finally, it was found that sex and age (within the limited fourth- to sixth-grade range examined in the present study) did not alter the overriding difference in attributional style between low and high self-esteem children.This study is based on a doctoral dissertation submitted by the first author under the supervision of the last author in partial fulfillment of the requirements for the Ph.D. degree at the University of Vermont.