In vitro studies suggest that cerebrovascular contraction is more dependent on the influx of calcium to smooth muscle than general systemic arteries. The present study tested the in vivo effects of a calcium influx blocker (nimodipine) on cerebral blood flow and metabolism in 16 baboons. The 133xenon clearance technique was used together with careful control of EEG and blood gases. With normal blood gases intravenous nimodipine infusion (1 microgram/kg/min) produced an 18% increase in cerebral blood flow with no alteration in cerebral oxidative metabolism or blood pressure. Higher doses (above 10 micrograms/kg/min) resulted in a decreased arterial blood pressure and a return to control cerebral flow. Infusion of the dose producing maximal increase in flow, decreased the cerebral reactivity to altered PCO2 (n = 5). These results suggest that nimodipine may be a relatively selective cerebrovascular dilator.

Animals↗

PubMedDate not supplied

Increased expression of interleukin-8 and aminopeptidase N by cell-cell contact: interleukin-8 is resistant to degradation by aminopeptidase N/CD13.

In rheumatic joints, high concentrations of interleukin-8 (IL-8) have been measured in synovial fluid and in pannus tissue. In both locations aminopeptidase N (APN)/CD13, an exopeptidase with reported activity towards IL-8 is also present. The surprising stability of IL-8 in the presence of an alleged IL-8-degrading peptidase prompted us to undertake the present study. Cocultivation of fibroblast-like synoviocytes (SFC) with T cells or with T lymphocytic cell membranes, or of T cells with SFC cell membranes, all resulted in increased IL-8 mRNA expression and IL-8 secretion into the medium, and an increase of APN expression on lymphocytes. IL-8 degradation was monitored by Western blots and HPLC. IL-8(72), as a partially processed form, was used throughout this study since it is abundant in tissues and has increased biological activity in comparison to IL-8(77). Thus its degradation/inactivation is considered of high biological significance. Whereas trypsin as a positive control rapidly degraded IL-8, we did not see any IL-8 degradation, either by a variety of soluble APNs, by leucine aminopeptidase or by APN expressed on the surface of SFC, or on ECV304 cells transfected with an APN expression vector. The much more sensitive HPLC technique resulted in negative results as well.

CD13 Antigens↗

PubMedDate not supplied

[Specific knowledge on hydatidosis in a rural sector population of the province of Valdivia, Chile].

Explore the source record for details and available documents.

Adolescent↗