No abstract

Crinoid echinoderms can completely and rapidly regenerate arms lost following self-induced or traumatic amputation. Arm regeneration in these animals therefore provides a valuable experimental model for studying all aspects of regenerative processes, particularly with respect to the nervous system and its specific contribution to regenerative phenomena. Taking into account the primary role of the nervous system in regeneration in other invertebrates, we have investigated the specific involvement of neural factors, viz. the monoamine neurotransmitters dopamine and serotonin, in arm regeneration of Antedon mediterranea. In the present work, the presence of classical monoamines has been revealed by employing specific immunocytochemical and histofluorescence tests in association with biochemical detection by means of high pressure liquid chromatography. The distribution pattern of these neurohumoral molecules at standard regenerative stages has been compared with that of normal non-regenerating arms. Results indicate that both dopamine and serotonin dramatically change in both their distribution and concentration during the repair and regenerative processes. Their remarkably enhanced pattern during regeneration and widespread presence at the level of both nervous and non-nervous tissues indicates that they are important neural growth-promoting factors in crinoid arm regeneration.& k w d :

Background: The interleukins IL-4 and IL-13 play a key role in the pathophysiology of asthma. The interleukin receptor IL-13Rα2 is believed to act as a decoy receptor, but until now, the functional significance of IL-13Rα2 remains vague. Methods: Bronchial reactivity was quantified in murine lung slices by digital video microscopy and acetylcholine (ACH)-induced Ca²⁺ signaling was measured in human airway smooth muscle cells (ASMC) using fluorescence microscopy. Results: IL-4 or IL-13 up to 50 ng/ml induced bronchial hyperreactivity. But after incubation with 100 ng/ml this effect was lost and bronchial responsiveness was again comparable to the control level. The effects of IL-4 and IL-13 on bronchial reactivity were paralleled by the effects on ASMC proliferation. Fifty nanograms per milliliter of IL-4 and IL-13 increased the Ca²⁺ response of human ASMC to ACH. At 100 ng/ml, however, the effects of the cytokines on the Ca²⁺ response were no longer evident. The expression of IL-13Rα2 increased with increasing concentrations of IL-4 or IL-13, reaching its maximum at 100 ng/ml. Blocking IL-13Rα2, the loss of the effect of IL-4 and IL-13 at 100 ng/ml on human ASMC proliferation and the ACH-induced Ca²⁺ response were no longer present. Conclusions: IL-4 and IL-13 induce bronchial hyperreactivity by changing the Ca²⁺ homeostasis of ASMC. These effects are counteracted by IL-13Rα2. The biological significance of IL-13Rα2 might be a protective function by regulating IL-13- and IL-4-mediated signal transduction and thereby limiting pathological alterations in Th2-mediated inflammatory diseases.

The distribution of cell adhesion molecules in the normal human lung was investigated using antibodies to E-selectin, P-selectin, intercellular adhesion molecule 1(ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1). Lectin staining by Ulex europaeus type I agglutinin (UEA I) and immunohistochemistry for von Willebrand factor (vWF) was used to visualize a maximum of blood vessels per section. In the bronchial mucosa, staining for P-selectin was positive in ca 90%, and staining for E-selectin, VCAM-1, and ICAM-1 was positive in 40-70% of the vessels stained with UEA I. In the pulmonary circulation (vasa publica) ca 90% of non-capillary vessels stained by anti-vWF expressed P-selectin, 54% VCAM-1, 41% E-selectin, and only ca 20% ICAM 1. The alveolar capillaries were stained consistently by UEA I, but not by the panel of antibodies tested. The alveolar epithelium and, inconstantly, basal cells of the bronchial epithelium were positive for ICAM-1. The distribution pattern of inducible adhesion molecules in normal human lung tissue suggests that a permanent low-grade endothelial activation may exist in particular in the mucosa of the airways, which could be due to the normal antigen exposure via inhaled air.

Chlamydial HSP 60 can often be demonstrated in primary coronary stenosis of symptomatic patients. It is most frequently found in macrophages/foam cells and is highly prevalent in the acute coronary syndrome. In-situ findings suggest a pathogenetically relevant role of chronic persistent infection of Chlamydia pneumoniae in unstable coronary plaques.