994 resultados para RHO-FAMILY GTPASES


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This article draws on the author's experience of living and working in Belfast, Northern Ireland. Connections between the traumatic events of September 11 and the situation in the north of Ireland of ongoing civil conflict and violence are developed and aspects of therapeutic practice are described. Coping with the effects of trauma presents systemic therapists with multiple and complex challenges in whatever sociopolitical context they practice. A therapist stance that combines flexibility and openness of attitude with the creative use of therapeutic practices, including those from other modalities, will assist systemic therapists in rising to these challenges.

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In human neutrophils, beta2 integrin engagement mediated a decrease in GTP-bound Rac1 and Rac2. Pretreatment of neutrophils with LY294002 or PP1 (inhibiting phosphatidylinositol 3-kinase (PI 3-kinase) and Src kinases, respectively) partly reversed the beta2 integrin-induced down-regulation of Rac activities. In contrast, beta2 integrins induced stimulation of Cdc42 that was independent of Src family members. The PI 3-kinase dependency of beta2 integrin-mediated decrease in GTP-bound Rac could be explained by an enhanced Rac-GAP activity, since this activity was blocked by LY204002, whereas PP1 only had a minor effect. The fact that only Rac1 but not Rac2 (the dominating Rac) redistributed to the detergent-insoluble fraction and that it was independent of GTP loading excludes the possibility that down-regulation of Rac activities was due to depletion of GTP-bound Rac from the detergent-soluble fraction. The beta2 integrin-triggered relocalization of Rac1 to the cytoskeleton was enabled by a PI 3-kinase-induced dissociation of Rac1 from LyGDI. The dissociations of Rac1 and Rac2 from LyGDI also explained the PI 3-kinase-dependent translocations of Rac GTPases to the plasma membrane. However, these accumulations of Rac in the membrane, as well as that of p47phox and p67phox, were also regulated by Src tyrosine kinases. Inasmuch as Rac GTPases are part of the NADPH oxidase and the respiratory burst is elicited in neutrophils adherent by beta2 integrins, our results indicate that activation of the NADPH oxidase does not depend on the levels of Rac-GTP but instead requires a beta2 integrin-induced targeting of the Rac GTPases as well as p47phox and p67phox to the plasma membrane.

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Stock enhancement experiments of European lobster (Homarus gammarus) have been carried out around the Kvitsoy Islands in south-western Norway since 1990. In addition to releases of coded wire tagged lobster juveniles (cultured) and subsequent monitoring of commercial fishery, a lobster hatchery was established in 1997. Several experiments were made on the communal-rearing approach where the performance of mixed larval groups (families) was evaluated under identical conditions. Berried females of wild and cultured origin and their respective fertilised eggs were screened by using microsatellite DNA profiling involving a multiplex set of six lobster specific primers, thereby allowing determination of both parental genotypes. Each female were kept separately during hatching, and the offspring were later mixed and raised in a communal rearing system. The early-larval survival was estimated at stage IV (bottom stage), and the survivors were identified to family and group by microsatellite profiling. Five different communal experiments were conducted, representing offspring from 65 berried females. Of the surviving larvae, 6.3% could not be assigned to family due to degraded DNA and no PCR amplification. Significant differences in early survival between offspring of wild and cultured origin were found in the experiments. No differences between the groups were found in stage IV larval size. Based on the pooled data on survival (as a measure of early larvae fitness) offspring of cultured females displayed a relative fitness of 60% in comparison to offspring from wild females. Large variation in survival was also observed among families within the wild and cultured groups, suggesting a genetic component for these traits and a potential for selective breeding.

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Vascular insufficiency and retinal ischaemia precede many proliferative retinopathies and stimulate secretion of vasoactive growth factors. Vascular endothelial growth factor (VEGF) plays a major role and we therefore investigated the other members of the VEGF family: Placental growth factor (PlGF), VEGF-B, -C, and -D, and platelet derived growth factors (PDGF) A and B. Neonatal mice were exposed to hyperoxia for 5 days and then returned to room air (resulting in acute retinal ischaemia). RT-PCR demonstrated that all the members of the VEGF family are expressed in the retina and in situ hybridization (ISH) located their mRNAs primarily in ganglion cells. Similarly to VEGF itself, VEGF-C, PDGF-A, and PDGF-B were upregulated during retinal ischaemia (P < 0.05). Only PlGF gene expression increased during hyperoxia (P < 0.01). The expression pattern of these growth factors suggests a role in the normal retina and during vaso-obliterative and ischaemic phases.