Fibrillin Immunoreactive Fibers Constitute a Unique Network in the Human Dermis: Immunohistochemical Comparison of the Distributions of Fibrillin, Vitronectin, Amyloid P Component, and Orcein Stainable Structures in Normal Skin and Elastosis

Fibrillin, a 350-kD glycoprotein, was recently localized to elastin-associated 10nm microfibrils. Here, the distribution of fibrillin immunoreactivity was determined in normal skin in individuals of different ages and in lesions of solar elastosis or anetoderma. It was compared with the distribution of orcein-stainable fibers and with the immunoreactivities of vitronectin and amyloid P component. These glycoproteins are known to occur in conjunction with the orcein-stainable elastic fibers in adults, but not in the young. Fibrillin immunoreactivity was associated with orcein-stainable fibers in normal skin of both adults and the young. In addition, the fibrillin immunoreactive fiber network comprised fine fibers that were unstainable by orcein, anti-vitronectin, or anti- amyloid P component. Such fine fibers were especially abundant close to the dermal-epidermal junction zone. Immunoreactivities of anti-vitronectin and anti-amyloid P component were not always associated with fibrillin immunoreactivity but were consistently found to co-localize with orcein-stainable fibers in adults. This suggests vitronectin and amyloid P component to be associated with the amorphous elastin rather than with the microfibrils, although alternative interpretations are possible. In elastotic lesions, fibrillin immunoreactivity was generally fainter than that obtained using anti-vitronectin or anti-amyloid P component. In contrast, an extensive network of dermal fibers stained by anti-fibrillin, but not by anti-amyloid P component, anti-vitronectin, or orcein, was seen in an anetoderma lesion. In conclusion, fibrillin immunoreactivity is associated with a unique dermal network, which ultrastructurally is composed of microfibrils. These fibers are proposed to have an important structural and functional role in anchoring the dermal elastic fibers in the extracellular matrix and to the lamina densa

Tissue Vitronectin in Normal Adult Human Dermis Is Non-Covalently Bound to Elastic Tissue

Vitronectin is a multifunctional human plasma glycoprotein at is also found in constant association with elastic tissue fibers in normal adults. We have investigated the nature of the association of vitronectin with elastic tissue, and compared it to that of other elastic fiber-associated proteins, namely fibrillin and amyloid P component. Samples of normal human dermis were incubated with a variety of extraction agents, including high molar salt solution, non-ionic detergent (Nonidet P-40), the reducing agents dithiothreitol or 2-mercaptoethanol, and the chaotropic agents sodium dodecyl sulfate or guanidine hydrochloride. Vitronectin purified from serum typically migrates as two bands of 75 and 65 kD. By contrast, immunoblotting studies of residual dermal material after extraction with the various agents revealed only lower molecular weight (58, 50, 42, 35, and 27 kD) anti-vitronectin reactive bands. Although these bands may represent degradation products of vitronectin generated as a result of the extraction procedure, we cannot exclude the possibility that tissue vitronectin is distinct from plasma vitronectin. Anti-vitronectin reactive polypeptides co-migrating with the 58-, 50-, and 42-kD bands were solubilized following extraction with sodium dodecyl sulfate or guanidine hydrochloride, but not with the other extraction agents. Immunofluorescence studies using residual dermal material after extraction with guanidine hydrochloride demonstrated a marked reduction in elastic fiber staining intensity with anti-vitronectin and anti-amyloid P component, but not with anti-fibrillin. Thus the majority, if not all of dermal vitronectin, is, like amyloid P component, non-covalently associated with, and not an integral constituent of, elastic fibers

Gas6 and the Receptor Tyrosine Kinase Axl in Clear Cell Renal Cell Carcinoma

BACKGROUND: The molecular biology of renal cell carcinoma (RCC) is complex and not fully understood. We have recently found that the expression of the receptor tyrosine kinase Axl in the RCC tumors independently correlates with survival of the patients. PRINCIPAL FINDINGS: Here, we have investigated the role of Axl and its ligand Gas6, the vitamin-K dependent protein product of the growth arrest-specific gene 6, in clear cell RCC (ccRCC) derived cells. The Axl protein was highly expressed in ccRCC cells deficient in functional von Hippel-Lindau (VHL) protein, a tumor suppressor gene often inactivated in ccRCC. VHL reconstituted cells expressed decreased levels of Axl protein, but not Axl mRNA, suggesting VHL to regulate Axl expression. Gas6-mediated activation of Axl in ccRCC cells resulted in Axl phosphorylation, receptor down-regulation, decreased cell-viability and migratory capacity. No effects of the Gas6/Axl system could be detected on invasion. Moreover, in ccRCC tumor tissues, Axl was phosphorylated and Gas6 gamma-carboxylated, suggesting these molecules to be active in vivo. SIGNIFICANCE: These results provide novel information regarding the complex function of the Gas6/Axl system in ccRCC

Debates of the European Parliament. Report of Proceedings from 15 to 19 September 1980. No. 1-260. 1980-1981 Session

Activated protein C (APC) down-regulates thrombin formation through proteolytic inactivation of factor Va (FVa) by cleavage at Arg(506) and Arg(306) and of factor VIIIa (FVIIIa) by cleavage at Arg(336) and Arg(562). To study substrate recognition by APC, active site-mutated APC (APC(S360A)) was used, which lacks proteolytic activity but exhibits anticoagulant activity. Experiments in model systems and in plasma show that APC(S360A), and not its zymogen protein C(S360A), expresses anticoagulant activities by competing with activated coagulation factors X and IX for binding to FVa and FVIIIa, respectively. APC(S360A) bound to FVa with a K(D) of 0.11 ± 0.05 nm and competed with active site-labeled Oregon Green activated coagulation factor X for binding to FVa. The binding of APC(S360A) to FVa was not affected by protein S but was inhibited by prothrombin. APC(S360A) binding to FVa was critically dependent upon the presence of Arg(506) and not Arg(306) and additionally required an active site accessible to substrates. Inhibition of FVIIIa activity by APC(S360A) was >100-fold less efficient than inhibition of FVa. Our results show that despite exosite interactions near the Arg(506) cleavage site, binding of APC(S360A) to FVa is almost completely dependent on Arg(506) interacting with APC(S360A) to form a nonproductive Michaelis complex. Because docking of APC to FVa and FVIIIa constitutes the first step in the inactivation of the cofactors, we hypothesize that the observed anticoagulant activity may be important for in vivo regulation of thrombin formation

Leading with care: four mentor metaphors in collaboration between teachers and researchers in action research : (Translated from the Swedish and revised by the authors)

Mentoring is a central aspect of action research processes and raises ethical issues concerning roles and responsibilities, particularly when teachers and researchers collaborate. The purpose of the study is to explore mentoring and the roles of mentors in action research from an ethical stance. The theoretical basis is the philosophy of care ethics developed by the American educational philosopher, Nel Noddings. Participants in the study included one researcher and three teachers with experience serving as mentors in action research. Data collection included written reflections and collegial conversations on mentoring. Thematic analysis and the domain interactional model were used in the analysis, where four mentor metaphors in action research emerged: the gardener, the shepherd, the teacher and the bridge-builder. All roles can be practiced at the same time; sensitivity determines when a mentor moves in and out of different roles. The study finds that care ethics can contribute to an increased understanding of mentoring as something situated and relational, where a symmetrical approach between mentor and mentee is emphasized. The goal of mentoring should not be to treat everyone equally, but instead to build relationships on the individual level in order to establish mutual trust based on individual needs. The study shows that the four mentor metaphors can serve as a useful tool for critical reflection on the complexity of the mentor role and accordingly, the renegotiation of stereotypical mentor roles in relation to the quality of teaching.This is a translated and revised version of a paper which was first published in Swedish under the title ”Att leda med omsorg: fyra handledningsmetaforer i aktionsforskning” (Bergmark et al., Pedagogisk forskning i Sverige, Vol. 27 nr 2 2022. DOI: 10.15626/pfs27.02.02)</p

Att leda med omsorg: fyra handledningsmetaforer i aktionsforskning

Intresset för praktiknära skolforskning är idag stort. Aktionsforskning är en populär form för samarbete mellan forskare och lärare där handledning är centralt. Syftet med denna studie är att problematisera handledning och handledarroller i aktionsforskningsprojekt. Som teoretisk grund ligger den amerikanska utbildningsfilosofen Nel Noddings omsorgsetik. Deltagarna i studien är en forskare och tre lärare som alla har erfarenheter av att leda aktionsforskningsprojekt genomförda inom kommunal skolverksamhet. Datainsamling har skett genom skriftliga reflektioner och kollegiala samtal om handledning och handledarroller. Analysen har utgått ifrån tematisk analys och domäninteraktionsmodell. I analysen framträder fyra handledningsmetaforer i aktionsforskning: trädgårdsmästaren, herden, läraren och brobyggaren. Alla rollerna kan praktiseras samtidigt och fingertoppskänsla avgör när en handledare går in i och ut ur olika roller. Slutsatsen är att omsorgsetik kan bidra till ökad förståelse för handledning som något situerat och relationellt, där ett symmetriskt förhållningssätt mellan handledare och handledd betonas. I handledning är det viktigt att inte behandla alla likadant, utan att i stället lära känna varandra som individer, ha tilltro till varandra och visa omsorg baserad på specifika behov. Handledarens roll omfattar att skapa förståelse för andras perspektiv samt att inbjuda till kommunikation och reflektion. Utifrån studiens resultat kan konstateras att de fyra metaforerna för handledarroller är användbara för att belysa komplexiteten i handledarroller och för att bidra till underlag för reflektion och omformulerande av stereotypa handledarroller

Analysis of Gas6 in Human Platelets and Plasma.

Objective - Gas6 is a member of the vitamin K-dependent protein family. Gas6- deficient mice were found to be resistant to thrombosis because of defective platelet function. Mouse Gas6 was demonstrated to be present in platelets and found to be involved in platelet aggregation. The aim of this study was to investigate the presence of Gas6 in human platelets and plasma and determine its role in platelet function. Methods and Results - The presence of Gas6 in human platelets and plasma was analyzed using sensitive immunologic methods. Mass spectrometry and ELISA were used to identify and quantify Gas6 in plasma. Gas6 was demonstrated to be present in human plasma, at a concentration determined to be 13 to 23 ng/mL (0.16 to 0.28 nM). Furthermore, plasma Gas6 levels were found to be lower in patients administered with warfarin. However, Gas6 was undetectable in human platelets. Conclusions - This is the first report to identify and quantify Gas6 in human plasma. However, Gas6 protein was not detected in human platelets, suggesting that any potential platelet-specific function could be because of Gas6 from the circulation. These findings open up new directions regarding the role of Gas6 in normal and pathophysiological situations such as inflammation, autoimmune disease, thrombosis and arteriosclerosis