ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Lymphocyte activation and capping of hormone receptors (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 37 (1988), S. 131-150 
    Details
    ISSN: 0730-2312
    Keywords: hormone-receptor interaction ; hormone receptor exposure ; receptor patching/capping ; contractile proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: In this study both a Ligand-dependent treatment [concanavalin A (Con A)] and a ligand-independent treatment [high-voltage pulsed galvanic stimulation (HVPGS)] have been used to initiate lymphocyte activation via a transmembrane signaling process. Our results show that both treatments cause the exposure of two different hormone [insulin and interIeukin-2 (IL-2)] receptors within the first 5 min of stimulation. When either insulin or IL-2 is present in the culture medium, the stimulated lymphocytes undergo the following responses: (1) increased free intra-cellular Ca2+ activity; (2) aggregation of insulin or IL-2 receptors into patch/cap structures; (3) tyrosine-kinase-specific phosphorylation of a 32-kd membrane protein; and finally (4) induction of DNA synthesis.Further analysis indicates that hormone receptor capping is inhibited by (1) cytochalasin D, suggesting the involvement of microfilaments; (2) sodium azide, indicating a requirement for ATP production; and (3) W-5, W-7, and W-12 drugs, implying a need for Ca2 + /calmodulin activity. Treatment with these metabolic or cytoskeletal inhibitors also prevents both the tyrosine-kinase-specific protein phosphorylation and DNA synthesis which normally follow hormone receptor capping. Double immunofluorescence staining shows that actomyosin, Ca2+/calmodulin, and myosin light-chain kinase are all closely associated with the insulin and IL-2 receptor cap structures.These findings strongly suggest that an actomyosin-mediated contractile system (regulated by Ca2+, calmodulin, and myosin light-chain kinase in an energy-dependent manner) is required not only for the collection of insulin and IL-2 receptors into patch and cap structures but also for the subsequent activation of tyrosine kinase and the initiation of DNA synthesis. We, therefore, propose that the exposure and subsequent patching/capping of at least one hormone receptor are required for the activation of mouse splenic T-Iymphocytes.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240370202
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Electric stimulation of human fibroblasts causes an increase in Ca2+ influx and the exposure of additional insulin receptors (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 140 (1989), S. 379-385 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previously we reported that treating human fibroblasts in cell culture with high-voltage, pulsed galvanic stimulation (HVPGS) can significantly increase cellular protein and DNA synthesis (Bourguignon and Bourguignon: FASEB J., 1:398-402, 1987). In this study we have identified two of the early cellular events which occur following exposure to HVPGS: (1) an increase in Ca2+ uptake from the external medium and (2) an increase in the number of insulin receptors on the fibroblast cell surface. The increase in Ca2+ uptake begins within the first minute of electric stimulation while increased insulin binding is not detected until the second minute of stimulation. The HVPGS-induced increase in insulin binding can be inhibited by bepridil, a specific Ca2+ channel blocker, suggesting that the Ca2+ influx is required for the exposure of additional insulin receptors on the cell surface.Furthermore, we have determined that the addition of insulin to electrically stimulated cultures results in (1) an immediate, second increase in Ca2+ uptake and (2) significant increases in both protein and DNA synthesis compared to cells which were not stimulated. All three of these insulin-dependent effects are also inhibited by bepridil.Based on these results, we propose that HVPGS initially triggers the opening of voltage-sensitive calcium channels in the fibroblast plasma membrane. The increased level of intracellular Ca2+ then induces the exposure of additional insulin receptors on the cell surface. If insulin is available to bind the additional receptors, the fibroblasts will significantly increase both protein and DNA synthesis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041400224
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    facet.materialart.
    Unknown
    Release of Microparticles During Blood Storage Is Influenced by Residual Platelets, Leukocytes and Oxygen Levels (2012)
    American Society of Hematology
    Details
    Publication Date: 2012-11-16
    Description: Abstract 3435 Introduction Packed red blood cells in blood bank undergo a series of changes and this so-called “storage lesions” increases with time. It is believed that longer storage is associated with adverse transfusion-related complications, but the reason for this is not clear. Many bioactive substances are generated during blood storage and one or more of them may be responsible for adverse events. Among them, red cell microparticles (RMP) are a leading candidate for adverse effects, but conditions influencing their release are not well identified. Elucidation of these conditions is an important step toward minimizing storage lesions. Methods (I) MP generation: Non-leukoreduced and leukoreduced PC of known blood types (A+, B+, AB+, O+) were obtained from the blood bank within 2–4 days of collection, then stored at 4°C. Time of receipt was defined as day 0. At days 0, 10, 20, 30, and 40, forty mL samples were centrifuged at 1000×g for 20 min to remove cells. The supernatants were then assayed for subtypes of MP by flow cytometry comprising (a) RMP assessed by CD235a, (b) leukocyte MP (LMP) by CD45, (c) platelet MP (PMP) by CD41, and (d) generic MP by Ulex Europaeus (Ulex) or annexin V (AnV); MP-mediated procoagulant and proinflammatory activities were determined by TEG and CD11b expression, respectively. (II) Storage under anaerobic conditions: Anaerobic test units were processed by an OCDD (Oxygen Carbon dioxide Depletion Device) to deplete O2 and CO2, then stored anaerobically in an Anaerobic Storage Bag (ASB) [Transfusion 2011:51S, SP89]. After 42 days, MP were assayed as above. Results (a) Time of storage: In non-leukoreduced RBC, multiple MP types (PMP, LMP, RMP) were detected and seen to increase with time, but at distinctive rates. RMP increased little until day 10 when they rose exponentially; PMP counts rose steadily from day 0 and peaked at day 20; LMP showed little change until day 20 when they began to increase, then rose sharply after day 30. Levels of PMP (days 0 to 20) and RMP (days 20 to 40) correlated with increasing MP-mediated procoagulant and inflammatory markers. (b) Leukoreduction: Pre-storage leukoreduction decreased RMP generation by 20–40% and completely suppressed PMP and LMP generation. Leukoreduction decreased total MP-mediated procoagulant and inflammatory markers by 40–60%. This suggests that residual leukocytes and/or platelets potentiate RMP generation. (c) Residual platelet concentrations: We added increasing numbers of platelets to leukoreduced RBC, and then evaluated RMP generation during storage. The levels of RMP released were proportional to platelet counts in the storage bags. (d) Residual oxygen: We observed that storage of leukoreduced RBC under anaerobic conditions resulted in 40 – 60% reductions in RMP and annexin V+ MP generation measured at 42 days. Conclusions Multiple MP species (RMP, PMP, LMP) are released during storage of non-leukoreduced PC and increased with time. Procoagulant and proinflammatory activities increased in parallel. Leukoreduction eliminates LMP and PMP generation and reduces RMP generation by 40–50%. This was accompanied by reduction of procoagulant and proinflammatory activities by 60%. We have identified residual platelets, leukocytes, and oxygen levels as important factors governing MP release in stored blood. Reduction or elimination of factors influencing MP generation such as residual platelets, leukocytes and oxygen levels would improve future blood storage condition. Disclosures: No relevant conflicts of interest to declare.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Elevated Cholinesterase Activity in Patients with TIA and Other Thrombotic Disorders. (2009)
    American Society of Hematology
    Details
    Publication Date: 2009-11-20
    Description: Abstract 2991 Poster Board II-967 Background. The natural function of ACTH in blood is not well defined. However elevated plasma level was reported in patients with chronic inflammation, suggesting as one of inflammatory markers. Erythrocytes possess membrane-bound acetylcholinesterase (AChE) while plasma contains a less specific cholinesterase (ChE). We reported at a previous meeting [Blood 2008, 112(11) Abst #3849] that AChE activity of RBC-derived microparticles (RMP) is 6 times higher than those in PMP. In this study we measured plasma ACTH levels in several groups and encountered unexpectedly high plasma ChE activities in patients with TIA and other thrombosis. Methods. (i) Patient population. A series of n=108 consenting patients were recruited sequentially having various disorders For purpose of analysis, they were divided in 2 main groups: n=53 with thrombosis (TBS), F/M 27/26; and n=55 non-TBS, F/M 24/31. Thrombosis group consists of venous and arterial thrombosis including those with TIA. Non TBS group consists of anemias, thrombocytopenias including ITP, MDS. (ii) Assay was essentially by Ellman's method. In our system, milli-absorbance units/min (mA/min) x 0.065 = umols substrate cleaved/min. Values reported here are in unitsof mA/min per mL plasma. Normal controls (NC, n=14) had a cutoff of 3000 mA/min per mL plasma, = mean +2SD. (iii) Sample handling. Platelet-poor plasma (PPP) was prepared by centrifuging 10 min at 1800 xg, then frozen in aliquots. For assay, it was diluted 1:20 with saline, then 5 uL and 10 uL were used in 96-well microtiter plate. Results: (i) Significantly higher ChE activity was observed in thrombosis (TBS) patients compared to non-TBS. Mean value ±SD in TBS was 2928 ±773, and in Non-TBS was 1897 ±713 (units as above). This difference was significant, p3000) in 30% of patients, while the Non-TBS had elevated ChE in 7.8%. (iii) Further analysis among thrombosis group revealed that the subgroup with neurological TBS (TIA, minor strokes) had the most consistent elevations of ACTH; 10 of15 with TIA group (66%) had ChE activities 〉3000. Summary/ Discussion. Although ChE and AChE in blood has long been studied, to our knowledge, this is the first report to show a relation between plasma ChE and thrombosis. Its elevation is very pronounce in thrombosis of the CNS, manifesting as TIA. Further study is warranted to elucidate how ChE is related to AChE of the CNS and on red cells. Disclosures: No relevant conflicts of interest to declare.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    Cell-Derived Microparticles (C-MP) Are Elevated in Splenectomized Patients and Depressed in Those with Hypersplenism, Suggesting Spleen as Scavenger of C-MP. (2006)
    American Society of Hematology
    Details
    Publication Date: 2006-11-16
    Description: BACKGROUND: Cell-derived microparticles (C-MP) are microvesicles released during activation and apoptosis from platelets (PMP), leukocytes (LMP), endothelial cells (EMP) and red cells (RMP). They commonly express phosphatidylserine (PS) judged by binding annexin V (AnV) and carry markers of parent cells. C-MP are involved in thrombosis, inflammation and angiogenesis. Little is known how C-MP are cleared from circulation. To test that the spleen might be involved, we investigated C-MP profiles in patients who underwent splenectomy for various causes (group A), those with hypersplenism (group B), and healthy controls with spleen (group C). MATERIAL AND METHODS: Group A (Gr A) consisted of 44 patients (18 M and 26 F, mean age 57.2 yr) with splenectomy; group B (Gr B) consisted of 25 patients (12 M and 13 F, mean age 61.6 yr) with hypersplenism. Gr A had 25 ITP, 7 myeloproliferative disorders, 4 lymphoma, 3 hemolytic anemias, 4 trauma related splenectomy, 1 unknown reason. Group B had 19 chronic hepatitis C, 2 alcoholic, 2 idiopathic and 1 autoimmune hepatitis, 1 portal vein thrombosis. Group C (Gr C) were healthy controls with spleen (n=109). Flow cytometry was used to assay C-MP. PMP were identified by CD41+, LMP by CD45+, EMP by CD31+/CD41−, and RMP by glycophorin+. Profile of C-MP and blood counts were compared among the 3 groups. RESULTS: Table 1 summarizes C-MP data among the 3 groups. Gr A and B were well matched for ages and sex. Mean values of WBC and Hgb were normal in all groups while the platelet count was low in Gr B. Mean values of LMP, EMP and RMP were significantly higher in Gr A compared to Gr B and C, but PMP were not. All species of C-MP (PMP, LMP, EMP, RMP) in Gr B were significantly lower than Gr C (healthy control) and were markedly depressed compared to Gr A (see Table 1). Correlation analysis revealed that PMP correlated with platelet count (p
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Effects of Intravenous Immunoglobulins (IVIG) on Cell-Derived Microparticles in Patients with ITP. (2007)
    American Society of Hematology
    Details
    Publication Date: 2007-11-16
    Description: INTRODUCTION: ITP is an autoimmune disease in which antiplatelet antibodies induce immune-mediated platelet destruction. Cell-derived microparticles (C-MP) are microvesicles released from blood cells as well as endothelial cells (EMP) upon activation or apoptosis of parent cells. MP released from platelets (PMP), leukocytes (LMP), red cells (RMP) and endothelial cells (EMP) are believed to participate in hemostasis, thrombosis and inflammation. We previously reported C-MP profiles in ITP and that platelet counts correlated directly with PMP, and inversely with RMP [V. Fontana et al, ASH 2006, Abst #1087]. This suggests that RMP reflect severity of platelet destruction in ITP. IVIG is widely employed in the treatment of ITP and is believed to ameliorate platelet destruction by down-regulating Fc receptors of macrophages. In this study, we investigated how IVIG infusion affects C-MP levels in ITP patients. METHODS: Nineteen patients with ITP (7M/12 F, mean age 57.5yr) who received IVIG (20–30 gm/day × 2–5 days) for treatment of ITP were studied. Platelet counts and C-MP were measured before and 24hr post-infusion of IVIG, and platelet counts were monitored for 2–3wks thereafter. Patients were classified as responders (R) or non-responders (NR) to IVIG. Criteria for R was a rise in platelet counts to ≥70,000 and ≥50% increase over pre-treatment values; NR had ≤70,000 and ≤50% incremental increase within 3 weeks of IVIG. Flow cytometry was employed to assay C-MP using fluorescent markers of CD45 (LMP), CD41 (PMP), CD31+/CD41− (LMP), and glycophorin (RMP). RESULTS: Table 1 summarizes mean values of platelet counts and C-MP in the R and NR groups. The R group had n = 10 patients (7F/3M, mean age 56.4 yr; mean platelets 35,000μL pre, 118,000μL post, p = 0.001), and the NR group had n = 9 patients (4M/5F, mean age 58.8 yr, mean platelets 44,000μL pre, 51,000μL post, p〉0.05, n.s.). Mean levels of PMP increased significantly in the R group (p = 0.02) but no change was seen in the NR group. RMP decreased significantly in both groups but the decrease was more significantly in the R group (p=0.002) than the NR group (p=0.01). No significant change in EMP or LMP was seen pre- vs. post-IVIG. CONCLUSION/DISCUSSION. The present study demonstrates that IVIG modulates C-MP levels in ITP. IVIG decreased RMP significantly in both groups but more so in R than NR groups. It increased PMP in R but not in NR, consistent with our previous report that PMP levels correlated with platelet counts. However there is no effect of IVIG on LMP and EMP. These findings are consistent with the concept that IVIG down-regulates immune-mediated platelet destruction and has little effect on activation of leukocyte or endothelium. Since RMP appear to reflect severity of ITP, the observed decrease of RMP in both groups post-IVIG may reflect amelioration of immune-mediated platelet destruction by IVIG therapy. The mechanism by which RMP are produced in ITP, and how IVIG reduces RMP, remains to be elucidated. Table 1. Data on patients and C-MP RESPONDERS NON-RESPONDERS Pre IVIgG Post IVIgG p value Pre IVIgG Post IVIgG p value Plt (count/microL) 35,000 118,000 0.001 44,000 51,000 n. s. C-MP (count/microL): EMP 204 223 n. s. 227 325 n. s. PMP 1,780 2,693 0.02 1,963 2,071 n. s. LMP 1,109 1,116 n. s. 1,056 1,957 n. s. RMP 1,597 1,030 0.002 1,456 603 0.01
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Surface Adhesion and Growth of Microaggregates under Flow Conditions (I): Role of Cell-Derived Microparticles and Leukocytes. (2007)
    American Society of Hematology
    Details
    Publication Date: 2007-11-16
    Description: BACKGROUND. Circulating blood cells and endothelial cells (EC) shed small membranous vesicles termed cell-derived microparticles (MP) upon activation or apoptosis. Many MP species carry procoagulant activity and cell adhesion molecules (CAM) which can mediate interactions with platelets, leukocytes and EC. Therefore, it has been proposed that some species of MP play important roles in hemostasis and thrombosis. To gain new insight on possible MP modulation of cell adhesion to surfaces under flow conditions, we evaluated effects of adding selected MP types to whole blood (WB) or to platelet-rich plasma (PRP) under flow conditions at physiological shear rates. METHODS. A cone-and-plate analyzer (CPA) equipped with microscope and imaging analysis software was used to investigate cell adhesion and growth of micro-aggregates on the plate surface under flow (shear) conditions (Diamed Impact-R). Citrated WB or PRP (110 μL) was preincubated with 20 μL of selected MP for 10 min, then subjected to 1800 sec−1 shear rate for 2 min. Endothelial MP (EMP) were obtained from the supernatant of cultured renal microvascular endothelial cells activated by TNF-α (10 nM) for 24 hr. Platelet MP (PMP) were generated by exposure of PRP to ADP (10 μM) for 30 min. Red cell MP (RMP) were prepared by exposure of washed RBC to calcium ionophore (10 μM) for 60 min. All MP were washed twice with PBS and resuspended at 2 × 106 /μL. Images of adherent microaggregates were measured in terms of percent surface coverage (SC), average size, and number of adherent objects. RESULTS. The difference between PRP and WB: There was 3-fold greater SC and 2-fold larger aggregate size in WB (p
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Endothelial Microparticles (EMP) Bind and Complex with Unusually-Large Multimers of Von Willebrand Factor (ULvWf) and Act as Potent Inducers of Platelet Adhesion and Aggregation. (2004)
    American Society of Hematology
    Details
    Publication Date: 2004-11-16
    Description: BACKGROUND . EMP have emerged as sensitive biomarkers of endothelial dysfunction. Little is known of their function. EMP interact with leukocytes and platelets and exert prothrombotic and proinflammatory effects. Recently we reported that vWf is expressed in EMP. The present study extends this observation to characterize EMP-bound vWf (EMP/vWf), specifically their multimer size and proaggregatory activity in ristocetin-induced platelet aggregation. METHODS . EMP, released from human renal microvascular endothelial cells 24hr following stimulation with TNF-α, were isolated by centrifugation (10,000g x 30min) and washed twice for vWf multimer analysis and proaggregatory activity assay. vWf multimer size was analyzed by 0.8% argarose gel electrophoresis and Western blotting. The proaggregatory activity of vWf was assessed flow ctyometrically by a two-step method: first, washed platelets were incubated with either EMP or soluble vWf such as plasma or Humate P (a commercial vWf multimers) in the presence of ristocetin for 10 min, then disappearance of free platelets as they formed small aggregates was measured. Second, the formed platelet aggregates were diluted 20-fold with buffer and degree of disaggregation was determined at intervals to assess the stability of PltAg. RESULTS . (i) Electrophoresis showed that vWf bands from normal plasma do not exceed 1,000 kDa and Humate P about 2,000 kDa while vWf bands on EMP extends much higher than 2,000 kDa. The protein banding pattern of EMP/vWf also differed from free soluble vWf (plasma) or humate P, the latter both showing clear ladder-like banding while EMP/vWf often appeared as a continuous smear of sizes in the high molecular weight regions, probably due to covalent bonds to transmembrane structures. (ii) Incubation of EMP (1 x 107 in 100 μL) with humate P (0.3 U) for 2hr (rotary shaker, 100 rpm) followed by washing the EMP revealed that significant additional vWf was adsorbed to the EMP: the vWf in the supernatant was decreased by 30% – 40%, and Western blotting showed additional high MW band on the treated EMP. This demonstrates that EMP express unoccupied sites capable of binding free vWf. (iii) Incubating EMP/vWf with washed platelets in the presence of ristocetin resulted in formation of platelet aggregates (PltAg). When PltAg were diluted 1:20, the PltAg began dissociating into free platelets in a time-dependent manner. The time for 50% dissociation of PltAg was 15–20min with soluble vWf (plasma or Humate P), but was prolonged to 45–60min with EMP/vWf. We attribute this mainly to the presence of ULvWf on EMP. (iv) Plasma from 4 acute TTP patients showed elevated EMP and enhanced formation of PltAg resistant to disaggregate. While 5 vWD plasma showed the opposite effect and their deficiency was corrected by added EMP. CONCLUSIONS . A new role of EMP is indicated in the present study. EMP-bound vWf is functionally active, inducing platelet aggregates of greater stability than free vWf in a ristocetin-based assay. EMP are capable of adsorbing additional vWf from plasma, indicating presence of extra binding sites. EMP enhance the stability of aggregates probably through ULvWf on the EMP, or to additional platelet-EMP-platelet adhesion molecules, or both. Through their high-affinity interaction with ULvWf, EMP likely play a role in vWf-dependent thrombotic disorders such as TTP and other platelet mediated thrombosis.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Increased Endothelial Colony-Forming Cells (ECFC) and Endothelial Microparticles (EMP) and Their Interaction in Thrombotic Thrombocytopenic Purpura (TTP). (2007)
    American Society of Hematology
    Details
    Publication Date: 2007-11-16
    Description: BACKGROUND. Endothelial damage is a prominent feature of TTP, evidenced by elevated EMP levels during acute episodes of TTP. However, endothelial repair in TTP remains to be investigated. ECFC are key players in endothelial regeneration, and their assay in blood has been employed to monitor endothelial remodeling. We investigated circulating ECFC in TTP and their relationship with EMP. METHODS. Six patients with acquired TTP were studied. All were treated with therapeutic plasma exchange (TPE). All but one underwent complete remission (CR). The one who failed to achieve CR with TPE suffered multiple strokes and developed chronic renal failure. We measured the following in acute phase and remission, as well as pre- and post-TPE: EMP defined by CD31+/CD42b- (EMP31) or CD62E+ (EMP62) by flow cytometry; ECFC in blood by the method of Ingram et al [Blood 104:2752, 2004]; ADAMTS13 activity in blood as well as in supernatants of ECFC-derived EC by the FRETS-vWF73 fluorogenic method. In addition, we investigated effects of microparticles (MP) from TTP plasma on normal ECFC. In separate experiments, EC cultured from TTP patients were assayed for surface expression of CD106 and CD54, and EMP released in response to TNF-α. RESULTS. In the acute phase, EMP were elevated: EMP31 (1.89 ± 0.65 × 106 counts/mL vs. 0.28 ±0.1 for controls, p=0.001) and EMP62 (5.7 ±1.3 × 106 counts/mL vs. 0.40 ±0.12 for controls, p
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Circulating CD62E Occurs in Soluble Form as Well as Bound to Endothelial Microparticles (EMP): Functional Differences in Platelet Aggregation in Thrombotic Thrombocytopenic Purpura (TTP). (2004)
    American Society of Hematology
    Details
    Publication Date: 2004-11-16
    Description: Injured endothelial cells (EC) are believed to play a critical role in the pathophysiology of TTP. Soluble markers of endothelial disturbance measured by enzyme-linked immunoassay (ELISA) have been found elevated in TTP. We have recently demonstrated an increase in the release of CD31/42b- EMP, and CD62E+ EMP. Moreover, we have observed that CD62E+ EMP also express vWF. The aim of this study was to quantitate soluble (s) vs. EMP-bound CD62E (bCD62E) in vitro and in vivo, in relation to the functional activity of vWF+ EMP. METHODS: Brain and renal microvascular endothelial cells (MVEC) were cultured and treated with 10ng/mL TNF-α to induce activation, or deprived of serum and growth factors (GFD) to induce apoptosis. Culture supernatants were collected and evaluated in a time-dependent manner. For in vivo studies, platelet-poor plasma was obtained from 4 TTP patients during the acute phase and upon remission. Filtration through 0.1μm, which retains most EMP, was employed to discriminate between (s) and bCD62E. sCD62E was measured by ELISA post-filtration and bCD62E by ELISA pre-filtration. Additionally, CD62E+ and CD62E+/vWF+ EMP were measured by flow cytometry. To assess pro-aggregatory function, EMP were added to washed platelets in the presence of 1 mg/mL ristocetin and aggregates were measured by flow cytometry. RESULTS: In vitro: Activation did not induce release of sCD62E at 3 hours, although bCD62E was present (1.5±0.5X106 EMP/mL). At 6 hours, some sCD62E was detected in the filtrate (0.09±0.02 ng/mL), but most was present in the unfiltered medium (3.5±0.85 ng/mL), signifying that the majority was bCD62E, confirmed by a doubling of CD62E+ EMP (3.0±0.6X106/mL). Subsequently, sCD62E levels were 1.0±0.2 ng/mL at 12 hr, 3.5±0.7 ng/mL at 18 hr, and 5±0.9 ng/mL at 24 hr. In contrast, EMP counts at 12, 18 and 24 hours were 4.6±1, 7±1.3 and 9±1.8 X106/mL (p=0.01, p=0.01, p=0.02, respectively). For all time periods, 40-60% of CD62E were positive for vWF. In control or GFD cultures, there was not a significant increase in sCD62E or CD62E+ EMP at any time period. MVEC from renal gave similar results. In acute TTP plasma samples, CD62E measured by ELISA was significantly increased (65±22 ng/mL) vs. remission (30±6 ng/mL). bCD62E accounted for 50% in acute and 15% in remission. CD62E+/vWF+ EMP were significantly elevated in plasma from acute TTP patients vs. remission (15±4.5 vs. 3±0.5, p=0.01). Sample filtration resulted in a decrease of 〉95% EMP in both acute and remission TTP plasma. MVEC-derived CD62E+/vWF+ EMP resulted in a dose-dependent increase in platelet aggregation. Additionally, plasma from 4 TTP patients with elevated CD62E+/vWF+ EMP obtained during the acute phase enhanced the formation of platelet aggregates by 48±12% (p=0.02) above remission plasma with low EMP counts. CONCLUSIONS: The results demonstrate that CD62E heretofore regarded as a soluble marker of endothelial dysfunction, in reality exists in both a soluble and EMP-bound form. Indeed, this distinction is highly relevant because CD62E+ EMP also express vWF and are pro-aggregatory to platelets. These EMP have been shown to be elevated during the acute phase of TTP and decrease upon remission. Thus, CD62E+/vWF+ EMP may be active participants in the formation of platelet-rich thrombi in TTP.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...