Structural composition and differential anticoagulant activities of dermatan sulfates from the skin of four species of rays, Dasyatis americana, Dasyatis gutatta, Aetobatus narinari and Potamotrygon motoro

We compared the disaccharide composition of dermatan sulfate (DS) purified from the ventral skin of three species of rays from the Brazilian seacoast, Dasyatis americana, Dasyatis gutatta, Aetobatus narinari and of Potamotrygon motoro, a fresh water species that habits the Amazon River. DS obtained from the four species were composed of non-sulfated, mono-sulfated disaccharides bearing esterified sulfate groups at positions C-4 or C-6 of N-acetyl galactosamine (GalNAc), and disulfated disaccharides bearing esterified sulfate groups at positions C-2 of the uronic acid and at position C-4 or C-6 of GalNAc. However, DS from the skin of P. motoro presented a very low content of the disulfated disaccharides. The anticoagulant actions of ray skin DS, measured by both APTT clotting and HCII-mediated inhibition of thrombin assays, were compared to that of mammalian DS. DS from D. americana had both high APTT and HCII activities, whereas DS from D. gutatta showed activity profiles similar to those of mammalian DS. In contrast, DS from both A. narinari and P. motoro had no measurable activity in the APTT assay. Thus, the anticoagulant activity of ray skin DS is not merely a consequence of their charge density. We speculate that the differences among the anticoagulant activities of these three DS may be related to both different composition and arrangements of the disulfated disaccharide units within their polysaccharide chains.     

Regulation of A1/Bfl-1 expression in peripheral splenic B cells

We analyzed here the expression of the prosurvival Bcl-2 homologue A1 in peripheral B cell compartment. We observed that A1 mRNA are highly expressed in peripheral B cells as compared with other anti-apoptotic genes of the Bcl-2 family such as bcl-xl and bcl-2 itself. The expression of A1 is up-regulated in immature B cells at the transition between transitional type 1 (T1) and type 2 (T2) cells, and remained highly expressed in mature (M) B cells. We, therefore, analyzed the effect of B cell antigen receptor (BCR) and BAFF receptor (BAFF-R) engagement on the regulation of A1 in total B220(+) cells but also FACS-sorted immature T1, T2 and M B cells. We demonstrated that only BCR engagement up-regulated the expression of A1 mRNA and protein. These results suggest that A1 may play a key role in antigen-dependent signals that are required for survival and/or proliferation of peripheral B cells.     

Pharmacodynamic equivalence of a decapeptyl 3-month SR formulation with the 28-day SR formulation in patients with advanced prostate cancer

AIMS: The objective of the study was to assess the pharmacodynamic equivalence of LHRH analogue triptorelin 3-month and 28-day SR formulations. METHODS: Patients with documented locally advanced or metastatic prostate cancer were randomized to receive one injection of the 3-month formulation (n = 63) or three injections at 28-day intervals of the 28-day formulation (n = 68). Group-chemical castration rates defined as the percentage of patients reaching a testosterone plasma level 相似文献   

Culture of large vessel endothelial cells on floating collagen gels promotes a phenotype characteristic of endothelium in vivo

The vascular endothelium in vivo is a remarkably quiescent cell layer that displays a highly differentiated and tissue-specific phenotype. Once established in culture, endothelial cells (EC) are phenotypically different from their in situ counterparts, displaying altered gene expression, increased mitotic index, and decreased cell density. To determine whether manipulating the microenvironment of cells in vitro would lead to a more differentiated phenotype, we cultured bovine aortic EC on floating collagen gels. EC cultured to confluence on floating gels for 24 or 48 hr display mitotic indices nearly identical to those of quiescent endothelium in vivo, nearly two log orders lower than that of EC cultured to confluence on plastic, and cell density on floating gels also resembles that observed for endothelium in vivo. Culture of EC on floating gels leads to decreased expression of platelet-derived growth factor-B, fibronectin, and fibronectin isoform ED-B, and increased levels of connexin40, relative to cells cultured on plastic. We conclude that culture of bovine aortic EC under standard culture conditions results in a phenotype reminiscent of development and/or wound healing, and that culturing them on a floating collagen gel leads to a more differentiated phenotype, reminiscent of that observed for large vessel EC in vivo.     

Conserved tertiary base pairing ensures proper RNA folding and efficient assembly of the signal recognition particle Alu domain

Proper folding of the RNA is an essential step in the assembly of functional ribonucleoprotein complexes. We examined the role of conserved base pairs formed between two distant loops in the Alu portion of the mammalian signal recognition particle RNA (SRP RNA) in SRP assembly and functions. Mutations disrupting base pairing interfere with folding of the Alu portion of the SRP RNA as monitored by probing the RNA structure and the binding of the protein SRP9/14. Complementary mutations rescue the defect establishing a role of the tertiary loop–loop interaction in RNA folding. The same mutations in the Alu domain have no major effect on binding of proteins to the S domain suggesting that the S domain can fold independently. Once assembled into a complete SRP, even particles that contain mutant RNA are active in arresting nascent chain elongation and translocation into microsomes, and, therefore, tertiary base pairing does not appear to be essential for these activities. Our results suggest a model in which the loop–loop interaction and binding of the protein SRP9/14 play an important role in the early steps of SRP RNA folding and assembly.     

The MMP/TIMP system in the nervous system

The matrix metalloproteinases (MMP) belong to a growing family of secreted or membrane-bound (MT-MMP) enzymes that cleave protein components of the extracellular matrix and bioactive factors involved in intercellular signaling. MMP activity is counterbalanced by their four physiological inhibitors, the tissue inhibitors of MMP (TIMPs). Together, MMP and TIMP control cell-cell and cell-matrix interactions associated with physiological processes. However, the breakdown of the protease-inhibitor balance may lead to the loss of tissue homeostasis and the development of degenerative and tumorigenic processes in various tissues. The emerging idea is that the MMP/TIMP system also plays a major role in the pathology and physiology of the nervous system and that mastering MMP activity will set the basis for new and more efficient therapeutic strategies against nervous system disorders.     

Profiling the CD8low phenotype, an alternative career choice for CD8 T cells during primary differentiation

A CD8+ T cell of naive phenotype has multiple career choices during its primary differentiation into an effector cell population. One of these career options is becoming a CD8low T cell. We have previously shown by in vitro studies that CD8low T cells have lost expression of CD8 surface protein and mRNA and are poorly cytolytic. In line with poor cytolytic function, CD8low T cells express low levels of perforin and granzyme B and C, mediators of the granule-exocytosis machinery. However, CD8low T cells express IFN-gamma and substantial amounts of IL-4, the signature cytokines of type 1 and type 2 T-cell polarization, respectively. Here, we argue that the CD8low phenotype is an alternative career choice for any naive CD8+ T cell during primary activation but that the probability of choosing this option is greatly enhanced by both IL-4 and strong activation conditions. CD8low T cells have downregulated CD8 alpha/beta heterodimers and no preferential CD8 alpha/alpha homodimer expression. As shown by anti-CD8 Ab blocking experiments, surface CD8 substantially contributes to the CD8 T cell's effector function (i.e. cytokine expression and cytolytic activity). The distinct effector profile of CD8low T cells gives an example of the complexity of different CD8 T cell careers during primary effector differentiation.