Is there a glycosaminoglycan‐related heterogeneity of the thymic epithelium?

Werneck, Cláudio C.; Cruz, Marcia S.; Silva, Luiz‐Claudio F.; Villa‐Verde, Déa Maria Serra; Savino, Wilson; Mourāo, Paulo A.S.

doi:10.1002/1097-4652(200010)185:1<68::aid-jcp6>3.3.co;2-4

Cited by 3 publications

(5 citation statements)

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“…Our results suggest the involvement of gap junctions and P2 receptors in the propagation of calcium waves in TNCs and the involvement of gap junctions in calcium wave propagation in TEC lines. Interestingly, preliminary evaluation of another TEC line, the IT-76M1 cells, which exhibit a mixed cortical/medullary phenotype (64), indicates the participation of both P2 receptors and gap junctions in ICW propagation (data not shown), suggesting that the participation of P2 receptors in ICW propagation is not limited to primary cultured TEC.…”

Section: Discussionmentioning

confidence: 99%

A novel form of cellular communication among thymic epithelial cells: intercellular calcium wave propagation

Nihei¹,

Carvalho²,

Spray³

et al. 2003

American Journal of Physiology-Cell Physiology

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We here describe intercellular calcium waves as a novel form of cellular communication among thymic epithelial cells. We first characterized the mechanical induction of intercellular calcium waves in different thymic epithelial cell preparations: cortical 1-4C18 and medullary 3-10 thymic epithelial cell lines and primary cultures of thymic "nurse" cells. All thymic epithelial preparations responded with intercellular calcium wave propagation after mechanical stimulation. In general, the propagation efficacy of intercellular calcium waves in these cells was high, reaching 80-100% of the cells within a given confocal microscopic field, with a mean velocity of 6-10 microm/s and mean amplitude of 1.4- to 1.7-fold the basal calcium level. As evaluated by heptanol and suramin treatment, our results suggest the participation of both gap junctions and P2 receptors in the propagation of intercellular calcium waves in thymic nurse cells and the more prominent participation of gap junctions in thymic epithelial cell lines. Finally, in cocultures, the transmission of intercellular calcium wave was not observed between the mechanically stimulated thymic epithelial cell and adherent thymocytes, suggesting that intercellular calcium wave propagation is limited to thymic epithelial cells and does not affect the neighboring thymocytes. In conclusion, these data describe for the first time intercellular calcium waves in thymic epithelial cells and the participation of both gap junctions and P2 receptors in their propagation.

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Section: Discussionmentioning

confidence: 99%

A novel form of cellular communication among thymic epithelial cells: intercellular calcium wave propagation

Nihei¹,

Carvalho²,

Spray³

et al. 2003

American Journal of Physiology-Cell Physiology

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“…The procedures used for isolation of the GAGs from the stromal cell cultures were similar to those previously described for other types of cells [Werneck et al, 1999, 2000; Carvalho et al, 2000]. Briefly, at the completion of the labeling period, conditioned media were removed and centrifuged (1,000 rpm for 5 min) to remove cell debris, and stored at −20°C until required.…”

Section: Methodsmentioning

confidence: 99%

“…Exhaustive enzymatic digestion with a mixture of heparin and heparan sulfate lyases was performed with three additions of the enzymes mixture (1 mU each) in 100 μl of 100 mM sodium acetate and 10 mM calcium acetate (pH 7.0) over a 36 h‐period at 37°C [Werneck et al, 2000].…”

Section: Methodsmentioning

confidence: 99%

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Biochemical characterization of heparan sulfate derived from murine hemopoietic stromal cell lines: A bone marrow‐derived cell line S17 and a fetal liver‐derived cell line AFT024

Arcanjo

Belo

Folco

et al. 2002

J of Cellular Biochemistry

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Heparan sulfate (HS) present on the surface of hemopoietic stromal cells has important roles in the control of adhesion and growth of hemopoietic stem and progenitor cells. Recent studies have characterized several different heparan sulfate proteoglycans (HSPGs) from both human and murine bone marrow stromal cells. In the present study, we have compared the molecular structure of HS, metabolically labeled with [(35)S]-sulfate produced by two distinct preparations of murine hemopoietic stromal cell lines. These comprised a bone marrow-derived cell line S17 and a fetal liver-derived cell line AFT024. [(35)S]-HS was examined in the cell layers and in the culture medium. We identified and measured the relative proportions of the various glycosaminoglycans (GAGs) in the two stromal cell lines. Chondroitin sulfate (CS) was preponderantly secreted by the stromal cell lines, while HS was relatively more abundant in the cell-associated fractions. The two types of stromal cells differ in their HS composition, mainly due to different patterns of N- and O-sulfation. The two stromal cell lines expressed mRNA for different HSPGs. Data from reverse transcription PCR revealed that the two stromal cell lines expressed mRNA for glypican and syndecan4. Only AFT024 cell line expressed mRNA for betaglycan. There was no evidence for expression of mRNA for both syndecan1 and syndecan2. [(35)S]-sulfated macromolecules could be released from the cell surface of both stromal cell lines by phosphatidylinositol phospholipase C (PI-PLC), which is consistent with the expression of glypican detected by PCR experiments.

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“…1D; see also Table S1 and Fig. S2), indicating a less sulfated molecule when compared with heparan sulfates from other sources [9,12,13]. But, more significantly, arterial heparan sulfate is more sulfated than the corresponding venous glycosaminoglycan, mostly due to ∼ 3‐fold higher N‐sulfation of the glucosamine residues and ∼ 2‐fold higher 2‐sulfation of the iduronic acid moieties (Fig.…”

Section: Resultsmentioning

confidence: 94%

Heparan sulfates from arteries and veins differ in their antithrombin-mediated anticoagulant activity

Mattos

Stelling

Tovar

et al. 2008

Journal of Thrombosis and Haemostasis

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The patient was then discharged in a stable condition. Because he moved to another city a few weeks after hospital discharge, a repeat TG assay was not possible. A telephone interview conducted 6 months later revealed that he did not experience any clinically obvious clotting abnormality again. In our patient, treatment with IVIG led to a normalization of hemostasis as confirmed by the TG assay, the disappearance of FV inhibitor, and the rise in FV activity. IVIG was given on the basis of its reported efficacy in patients with acquired hemo-philia A. However, a spontaneous recovery cannot be ruled out with certainty. The amount of thrombin generated, the lag phase and the time to thrombin peak are influenced by FV, as FV is part of every step in the process of TG [4]. Platelet FV rather than plasma FV plays a significant role in the amplification phase of coagulation. FV inhibitor leads to an impaired initiation phase, and this in turn results in impaired platelet activation. On the other hand, FV on the surface of activated platelets becomes neutraliszed by FV inhibitor, which leads to a reduction in prothrombinase activity and thrombin burst. The amount of FV needed to produce an adequate thrombin burst is still unclear. In our patient, minimal changes in FV activity from 7.4% to 8.6% led to a considerable increase in thrombin formation. Higher concentrations of FV did not result in any further increase in ETP, but did result in further reductions in the lag phase and the time to peak. Al Dieri et al. [5] observed no severe impairment in ETP at FV levels of 2% in patients with congenital FV deficiency. However, they used much higher TF concentrations (15 pM) in their assay. Therefore, their data are hardly comparable to ours. Furthermore , a measurable amount of the coagulation factor in the presence of an acquired autologous inhibitor may not necessarily correlate with its hemostatic function. Studies in patients with acquired autoantibody hemophilia A have shown that the inactivation has a type II pattern, with some residual FVIII activity being identifiable even after incubation at high concentrations of antibody. The presence of the inhibitor rather than the measurable coagulation factor activity is thus important in assessing the hemostatic state. In conclusion, the TG assay could be useful for monitoring hemostatic changes in patients with FV deficiency due to an inhibitor. However, there are issues of standardization to be dealt with. Clinical correlation with TG cutoff values is also lacking. These issues have to be addressed before the assay can be used in clinical routine practice. Disclosure of Conflict of Interests The authors state that they have no conflict of interest. References 1 Favaloro EJ, Posen J, Ramakrishna R, Soltani S, McRae S, Just S, Aboud M, Low J, Gemmell R, Kershaw G, Coleman R, Dean M. Factor V inhibitors: rare or not so uncommon? A multi-laboratory investigation Blood Coagul Fibrinolysis 2004; 15: 637-47. 2 Streiff MB, Ness PM. Acquired FV inhibitors: a needless iatrogenic compl...

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Is there a glycosaminoglycan‐related heterogeneity of the thymic epithelium?

Cited by 3 publications

References 0 publications

A novel form of cellular communication among thymic epithelial cells: intercellular calcium wave propagation

A novel form of cellular communication among thymic epithelial cells: intercellular calcium wave propagation

Biochemical characterization of heparan sulfate derived from murine hemopoietic stromal cell lines: A bone marrow‐derived cell line S17 and a fetal liver‐derived cell line AFT024

Heparan sulfates from arteries and veins differ in their antithrombin-mediated anticoagulant activity

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