Einige Befunde zur Sinnesphysiologie der Kaltblüterzecke Amblyomma testudinis

Zusammenfassung Aus eigener Zucht stammende Larven, Nymphen und Imagines von Amblyomma testudinis wurden auf ihre Sinnesleistungen hinsichtlich Phototaxis, Thermotaxis, Geotaxis und Chemotaxis untersucht. Es ergab sich ein entwicklungsabhängiger Wandel im phototaktischen Verhalten von anfangs positiver Phototaxis bei den Larven über indifferente Phototaxis bei vollgesogenen Larven und nüchternen Nymphen zu negativer Phototaxis bei vollgesogenen Nympen sowie - und -Imagines. Sämtliche Entwicklungsstadien mit Ausnahme der -Imagines verhalten sich temperaturindifferent vor dem Kontakt mit einem Wirt; vollgesogene Larven und Nymphen dagegen bevorzugen niedrige Temperaturen. Nymphen und Imagines, die noch nicht gesogen haben, reagieren negativ geotaktisch. Sie erklettern vermutlich in der Natur die Spitzen von Pflanzen und Steinen, um dort das Vorbeikriechen eines Wirtes abzuwarten. Imagines von Amblyomma testudinis reagieren mit einer positiven Chemotaxis auf Schlangen stärker als auf Kröten. Auch Substrat aus Schlangenbehältern enthält mindestens für 30 Std nach der Entfernung der Schlangen chemotaktisch wirksame Stoffe.

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Contributions to sensory physiology of the tick Amblyomma testudinis

Summary Phototaxis, thermotaxis, geotaxis and chemotaxis of larvae, nymphs and adults of Amblyomma testudinis from own breedings were studied. The phototactic behaviour changed according to the different stages of development: unfed larvae were positively phototactic, fed larvae and unfed nymphs were indifferent, fed nymphs but also the adults showed a negative phototaxis.—All stages of development besides the females reacted without any preference for a distinct temperature, whereas larvae and nymphs after feeding prefered lower temperatures.—Unfed nymphs and adults were negatively geotactic which corresponds to their natural behaviour of climbing plants for catching hosts.—Adults of Amblyomma testudinis showed a higher rate of chemotaxis for snakes than for toads; substrate from snake cages containes chemotaxis inducing substances for more than 30 hours after elimination of the snakes.

     

Sickle cell disease in Sicily.

The chemical and physical properties of haemoglobin S derived from homozygotes for this haemoglobin in Sicily were examined, as well as some erythrocytic characteristics. Sicilian Hb S was identical to that found in USA black patients in electrophoretic mobility on both starch and citrate agar media, solubility, mechanical precipitation rate of oxyhaemoglobins, and minimum gelling concentration, as well as by peptide mapping and amino-acid analysis of all beta-chain peptides. Taken together with the presence in Sicily of African blood group markers and certain historical considerations, it seems clear that the source of Hb S in Sicily is Africa. While the clinical severity in nine Sicilian children did not seem remarkably different from the disease in the USA, the most severe and fatal complications were not seen. Mean Hb F Was 10.5% and 2,3-diphosphoglycerate (2,3-DPG) values were higher in Sicilian homozygotes than in black USA counterparts (21.79 mumol/g Hb vs 15.16). Red cell AT values were also slightly higher in Sicilian patients. The presence of concomitant thalassaemia was excluded by both family studies and globin chain synthetic ratios. In conclusion, haemoglobin S in Sicilian homozygotes is identical to Hb S found in USA blacks. Although the severity of the disease seems quite similar in both groups of patients, other erythrocytic properties were found to be different. Whether these factors influence severity remains to be elucidated.     

A Novel Application of the MIRC Repository in Medical Education

Medical students on the radiology elective in our institution create electronic presentations to present to each other as part of the requirements for the rotation. Access was given to previous students presentations via the web-based system, Medical Imaging Resource Center (MIRC) project, created and supported by the Radiological Society of North America (RSNA). RadPix Power 2 MIRC (Weadock Software, LLC, Ann Arbor, MI) software converted the Microsoft PowerPoint (Redmond, WA) presentations to a MIRC-compatible format. The textual information on each slide is searchable across the entire MIRC database. Future students will be able to benefit from the work of their predecessors.     

B7-1 and B7-2 monoclonal antibodies modulate the severity of murine Lyme arthritis.

We assessed the role of B7-1 and B7-2 costimulatory molecules on the course of murine Lyme borreliosis because experimental Lyme arthritis is dependent, at least partially, upon the development of the host immune response and these costimulatory molecules have been implicated in CD4+ T-cell differentiation. We demonstrated that Borrelia burgdorferi infection upregulated the surface expression of B7-1 and B7-2 in macrophages and B7-2 expression in B cells. Anti-B7-2 monoclonal antibody (MAb) or both anti-B7-2 and anti-B7-1 MAbs produced a dose-dependent increase in the severity of Lyme arthritis in C3H/HeN mice. In contrast, the administration of an anti-B7-1 MAb reduced the degree of arthritis. These effects occurred independently of significant alteration in B. burgdorferi-specific immune responses, including splenocyte proliferative responses to B. burgdorferi, B. burgdorferi antibody levels and specificity, and mRNA levels of gamma interferon, interleukin-4 (IL-4), IL-10, and IL-12 in the spleen. These results demonstrate that signaling delivered by B7-1 and B7-2 plays a role in determining the severity of acute murine Lyme arthritis.     

Effects of dopamine autoreceptor stimulation on the release of colocalized transmitters: in vivo release of dopamine and neurotensin from rat prefrontal cortex

The in vivo release of dopamine and neurotensin from the rat medial prefrontal cortex was studied using perfusion microdialysis coupled with sensitive radioimmunoassay and HPLC techniques. Following stimulation of dopamine autoreceptors with either apomorphine (30 micrograms/kg, s.c.) or EMD-23448 (10 microM in the perfusion buffer) a decrease in dopamine and an increase in neurotensin release was observed. The release of both substances was measured in the same dialysis sample. These data suggest that activation of dopamine autoreceptors in the prefrontal cortex produces opposing effects on the release of dopamine and neurotensin.     

Impaired T cell proliferation, increased soluble death-inducing receptors and activation-induced T cell death in patients undergoing haemodialysis

Haemodialysis is a widespread option for end-stage renal disease (ESRD). Long-term success of dialysis is, however, limited by a high rate of serious bacterial and viral infections. We compared T cell functions in ESRD patients undergoing haemodialysis (n = 20), or were not dialysed and received conventional medical treatment (n = 20). Healthy volunteers (n = 15) served as controls. The T cell phenotype was examined by immunofluorescence using fluorochrome-labelled monoclonal antibodies and FACS analysis. The concentration of soluble CD95/Fas and of tumour necrosis factor-alpha receptor type 1 (sTNFR1) in the sera was quantified by ELISA. Activation-induced programmed T cell death was triggered by anti-CD3/CD28 antibodies and measured by 7-AAD staining. All immunological tests were performed at least 1 month after dialysis initiation. T cell proliferation in response to phytohaemagglutinin or anti-CD3 monoclonal antibodies was moderately diminished in non-dialysed patients and markedly reduced in haemodialysis patients compared to healthy controls (P < 0.01 and P < 0.001, respectively). In a mixed lymphocyte culture the proliferative response of T cells from dialysed patients was significantly diminished (P < 0.001). T cells of both non-dialysed and dialysed patients have augmented CD95/Fas and CD45RO expression, increased sCD95/Fas and sTNFR1 release and spontaneously undergo apoptosis. Culture of T cells from haemodialysis patients with anti-CD3/CD28 antibodies increased the proportion of CD4(+) T cells committing activation-induced cell death by a mean 7.5-fold compared to T-helper cells from non-dialysed patients (P < 0.001). Renal failure and initiation of haemodialysis results in a reduced proliferative T cell response, an aberrant state of T cell activation and heightened susceptibility of CD4(+) T cells to activation-induced cell death.     

Chronology of halothane-induced antigen expression in halothane-exposed rabbits.

Multiple halothane exposures in rabbits generate modified liver proteins or antigens that appear to incorporate the metabolic intermediate of halothane, trifluoroacetyl halide (TFA), as identified by specific anti-TFA antibody. These halothane-induced antigens are most prevalent throughout the second to fourth days following a single halothane exposure and are in highest concentration after the second and third exposure. In addition, five consecutive halothane exposures at 2-week intervals caused the sustained expression of these halothane-induced antigens throughout the first 4 days following the last exposure. By the seventh day, however, antigen expression began to decline. Although there is great heterogeneity in the molecular weights of the halothane-induced antigens, the predominant proteins appear to be 85k, 58k, 53k, 37k and 24k. These liver proteins could reflect self proteins altered by trifluoroacetylation by halothane metabolites and may be potential immunogens in the initiation of a halothane-induced immune response.