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L Corash

Publications and source records attributed to L Corash.

At least 73 records · Page 4Linked to original sources
PubMed1987

Evidence that a 210,000-molecular-weight glycoprotein (GP 210) serves as a platelet Fc receptor.

We previously identified a 210,000-mol-wt platelet glycoprotein (GP 210) that is missing from Bernard-Soulier platelets, and found that an antibody against GP 210 inhibits ristocetin-induced platelet agglutination. We now show by immunoblotting that GP 210 binds heat-aggregated rabbit and human IgG, as well as keyhole limpet hemocyanin (KLH)-anti-KLH and ovalbumin (OA)-anti-OA immune complexes. Immune complex binding to GP 210 was preserved on chymotrypsin-treated platelets that lacked glycoprotein Ib (GP Ib). In contrast, ristocetin-induced platelet agglutination resulted in disappearance of immunologically detectable GP 210 and loss of immune complex binding, even though GP Ib remained intact. Purified Fc fragments inhibited binding of anti-GP 210 antibody to intact platelets and to GP 210 on immunoblots. The Fc fragments also blocked immune complex binding to GP 210. Conversely, anti-GP 210 antiserum and F(ab)2 fragments inhibited binding of fluorescein-labeled Fc fragments to intact platelets. We conclude that GP 210 functions as a platelet Fc receptor.

Humans↗
PubMed1987

The frequency of lupus anticoagulant in systemic lupus erythematosus. A study of sixty consecutive patients by activated partial thromboplastin time, Russell viper venom time, and anticardiolipin antibody level.

Recent reviews have suggested a higher frequency of the lupus anticoagulant or related antiphospholipid antibodies in patients with systemic lupus erythematosus (21% to 65%) than was found in earlier studies (6% to 18%). In our study of 60 consecutive patients, we found the frequency of the lupus anticoagulant by Russell viper venom time was 6.7% (95% confidence interval, 16.2 to 1.8) and by anticardiolipin antibody assay was 25% (95% Cl, 37.0 to 15.7), compared with 0% (p = not significant) and 2.5% (p = 0.002), respectively, in the normal control population. The Russell viper venom time (p = 0.0001 by t-test) and anticardiolipin antibody levels (p = 0.01) were significantly associated with presumed thrombotic events (stroke, deep venous thrombosis, and digital gangrene). No association with miscarriage or pulmonary hypertension was detected. The Russell viper venom time was more specific than the anticardiolipin antibody level in the prediction of past presumed thrombotic events, miscarriage, or pulmonary hypertension (100% compared with 84%, p = 0.01).

Abortion, Spontaneous↗
PubMed1987

Posttransfusion purpura associated with an autoantibody directed against a previously undefined platelet antigen.

Although alloantibody against the PLA1 platelet antigen is usually found in patients with posttransfusion purpura (PTP), the mechanism of destruction of the patient's own PLA1-negative platelets is unexplained. We used a sensitive immunoblot technique to detect antiplatelet antibodies in a patient with classic PTP. The patient's acute-phase serum contained antibodies against three proteins present in control (PLA1-positive) platelets: an antibody that bound to a previously unrecognized platelet protein of mol wt 120,000 [glycoprotein (GP) 120], antibodies that bound to PLA1 (mol wt 90,000), and an epitope of GP IIb (mol wt 140,000). The antibodies against PLA1 and GP IIb did not react with the patient's own PLA1-negative platelets, control PLA1-negative platelets, or thrombasthenic platelets. In contrast, the antibody against GP 120 recognized this protein in all three platelet preparations, but not in Bernard-Soulier or Leka (Baka)-negative platelets. Antibody against GP 120 was not detected in the patient's recovery serum, although the antibodies against PLA1 and GP IIb persisted. F(ab)2 prepared from the patient's acute-phase serum also bound to GP 120. These results suggest that in PTP, transient autoantibody production may be responsible for autologous (PLA1-negative) platelet destruction. In addition, alloantibodies against more than one platelet alloantigen may be found in this disease. The nature of the GP 120 autoantigen and the GP IIb-related alloantigen defined by our patient's serum remains to be determined.

Aged↗
PubMed1987

Regulation of thrombopoiesis: effects of the degree of thrombocytopenia on megakaryocyte ploidy and platelet volume.

We have established a murine model and techniques with which to serially study thrombocytopoiesis after induction of experimental immune thrombocytopenia of variable severity and duration. Bone marrow megakaryocyte ploidy distribution was determined by using unfractionated bone marrow, a polyclonal megakaryocyte-specific probe, and two-color, fluorescence-activated flow cytometry. With these techniques, the modal megakaryocyte ploidy class in normal murine bone marrow was 16N. Serial studies of bone marrow megakaryocyte ploidy after the induction of acute, severe thrombocytopenia (platelet count, less than 0.05 X 10(6) microL) demonstrated no detectable change in the ploidy distribution at 12, 24, and 36 hours after the onset of thrombocytopenia. At 48 hours, the modal ploidy class shifted from 16N to 32N, and the 64N class increased significantly (P less than .001). The ploidy distribution returned to normal 120 hours after the onset of thrombocytopenia. A lesser degree of thrombocytopenia (platelet count reduction to 0.100 to 0.200 X 10(6)/microL) delayed the modal ploidy class shift from 16N to 32N until 72 hours after the onset of thrombocytopenia. Chronic, severe thrombocytopenia (platelet count, less than 0.05 X 10(6)/microL for seven days) resulted in a modal ploidy class shift from 16N to 32N during the thrombocytopenic phase and an enhanced increase in the 64N megakaryocyte class during the recovery phase. Mean platelet volume (MPV) was simultaneously measured on isolated total platelet populations after induction of thrombocytopenia. MPV was significantly increased (P less than .001) as early as eight hours after the onset of acute, severe thrombocytopenia, 40 hours before a shift in the ploidy distribution. Mild thrombocytopenia (platelet count reduction to 0.400 X 10(6)/microL) was not associated with a ploidy shift but did result in a significantly increased MPV (P less than .001). These studies demonstrate that the temporal relationship and magnitude of the effects of thrombocytopenia upon megakaryocyte ploidy distribution are dependent upon the degree and the duration of the thrombocytopenic stimulus and that the effects of experimental thrombocytopenia on platelet volume and megakaryocyte ploidy are dissociated.

Acute Disease↗
PubMed1985

Target platelet antigen in homosexual men with immune thrombocytopenia.

A syndrome of isolated immune thrombocytopenic purpura (ITP) has recently been described in homosexual men. We have identified an antiplatelet antibody in the serum of 29 of 30 homosexual men with isolated ITP. The antibody binds to a platelet membrane antigen of 25,000 daltons, and binding is effected by the F(ab)2 portion of the immunoglobulin. Similar antibody activity was not detected in serum from 30 nonhomosexual patients with either ITP or nonimmune thrombocytopenia. The 25,000-dalton antigen was not found on other hematopoietic cells, and it was distinct from the core protein of the AIDS-associated retrovirus. In contrast, serum antibody reacted with a 25,000-dalton antigen associated with cultured herpes simplex virus Types I and II. In these experiments the antigen appeared to be derived from green-monkey kidney cells in which the herpes simplex viruses were grown. Identical antigenic activity was also demonstrated in uninfected human skin fibroblasts. We conclude that ITP in homosexual men is accompanied by a serum antibody directed against a platelet antigen of 25,000 daltons. The nature of the antigen and the relation of the serum antibody to ITP require further study.

Antigens↗
PubMed1985

Acquired Bernard-Soulier syndrome. Evidence for the role of a 210,000-molecular weight protein in the interaction of platelets with von Willebrand factor.

A patient with a lymphoproliferative disorder developed bleeding associated with a prolonged bleeding time and a selective defect of platelet aggregation in response to ristocetin. The patient's purified IgG was shown to inhibit aggregation of washed normal platelets by ristocetin and von Willebrand factor (F VIII:vWF). By Western blotting, it was shown that antibody bound specifically to an antigen of Mr 210,000 present on normal platelets but missing on platelets from patients with congenital Bernard-Soulier syndrome (BSS). Binding was effected by the F(ab)2 portion of the IgG, indicating the presence of an autoantibody rather than an immune complex. These results suggest that the 210,000-Mr protein is involved in the interaction of F VIII:vWF with platelets. Furthermore, we have demonstrated the apparent absence of an additional protein on congenital BSS platelets. Heat-aggregated IgG was also shown to bind to the 210,000-Mr protein, suggesting that this protein may function as an Fc receptor on platelets. The relationship of the 210,000-Mr protein to glycoprotein Ib and the precise role of this protein in the interaction of platelets with F VIII:vWF need to be characterized.

Adult↗
PubMed1985

Platelet-associated immunoglobulin, platelet size, and the effect of splenectomy in the Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) thrombocytopenia is frequently improved by splenectomy, although the mechanism of the thrombocytopenia and its resolution are unknown. Previous studies in two patients have shown that mean platelet volume, which is characteristically reduced in WAS, increased along with platelet count postsplenectomy. Additional studies in a limited number of patients have also demonstrated that platelet-associated immunoglobulin G (PAIgG) is elevated presplenectomy, but to date no postsplenectomy data have been reported. The present study was performed to more fully evaluate the effect of splenectomy on platelet volume and PAIgG in WAS. Before splenectomy, mean platelet volume was reduced but platelet size was broadly distributed with substantial overlap of the normal range. PAIgG was significantly elevated in 13 of 14 presplenectomy WAS patients (means = 78.9 fg per platelet) and fell to normal levels postoperatively (means = 4.0 fg per platelet). Platelet count and clinical status improved postsplenectomy, and mean platelet volume and platelet volume distribution returned to the normal range. WAS subjects who relapsed with recurrent thrombocytopenia redeveloped elevated PAIgG but maintained normal platelet size. The spleen appears to play a critical role in a process that may be immunologically mediated and results in reduced platelet size.

Blood Platelets↗
PubMed1984

Acute megakaryoblastic leukemia in childhood.

Routine morphologic and cytochemical study of the leukemic cells of a 13-month-old child did not permit definitive determination of either a lymphoid or a myeloid cell origin. However, ultrastructural cytochemical analysis revealed platelet peroxidase (PPO) reactivity. The malignant cells expressed PPO in both unfixed and fixed preparations. PPO was observed in the perinuclear space and reticulum but not in the Golgi saccules. In a 1% glutaraldehyde, 1% formaldehyde solution known to inhibit PPO but not myeloperoxidase, no reaction product was observed. The demonstration of PPO activity in these undifferentiated cells established their megakaryoblastic lineage. Further studies including DNA flow cytometry confirmed that these cells were megakaryoblasts. This study demonstrates that megakaryoblastic malignancy may occur as an acute leukemia of childhood and emphasizes the value of ultrastructural cytochemistry in cases of acute leukemia which defy routine classification. Abnormalities of chromosome 21 were present in our patient as in four previous cases of megakaryoblastic leukemia in childhood. The nonrandomness of chromosome 21 involvement in this disease should therefore be considered.

Acute Disease↗
PubMed1984

Heterogeneity of human whole blood platelet subpopulations. III. Density-dependent differences in subcellular constituents.

Structurally intact platelet cohorts of differing densities can be isolated from normal subjects by the use of isosmolar arabinogalactan density gradients. Using platelets separated in this fashion, we have studied the density-dependent distribution of four subcellular organelles: mitochondria, lysosomes, dense bodies, and alpha granules. Mitochondria, which are not secreted during platelet release, demonstrate a slow decline in monoamine oxidase activity within the gradient. Lysosomal beta-glucuronidase does not vary significantly with platelet density. In contrast, dense body number and endogenous serotonin content decrease significantly with decreasing platelet density, primarily as the result of differences in the number of storage organelles. Platelet factor 4 content declines rapidly in comparison to lysosomal activities (P less than .001 from bottom to top of the gradient); but beta-thromboglobulin, also an alpha granule component, exhibits considerably less change than platelet factor 4 (P less than .001). Thus, specific platelet subcellular constituents have different density distributions. We postulate that these density differences may be due to differential in vivo loss of selective biochemical constituents from unique subcellular compartments.

Blood Platelets↗
PubMed1983

Ex vivo selective isolation of young red blood cells using the IBM-2991 cell washer.

Transfusion-induced hemochromatosis is a major complication in the therapy of severe chronic anemia. Improvement of transfused cell survival with a reduction in transfusion frequency is one possible approach to this problem. Using continuous-flow centrifugation (CFC), young red blood cells (YRBC) with enhanced in vivo survival have been isolated, but the expense and donor time required with this technique prohibit its widespread use for patient support. We studied the use of the IBM 2991 cell washer (CW) to isolate YRBC ex vivo from previously collected donor blood. Age-dependent red cell separation could be achieved using this instrumentation. Autologous mean red cell half-life (RBC-T50) (n = 9) for the younger cell fractions was 43.9 +/- 7.8 days compared to 34.7 +/- 5.8 days for the older cell fractions (n = 6, p less than 0.05). Paired measurement of RBC-T50 for young and old fractions in three donors showed an average survival increase of 41% for the YRBC. Adequate quantities of YRBC with enhanced survival can be obtained with less cost and less donor stress using the CW system compared to CFC. This approach could improve the management of patients with chronic transfusion requirements and merits further examination.

Blood Transfusion↗
PubMed1982

Factor VIII/von Willebrand factor binding to von Willebrand's disease platelets.

A form of von Willebrand's disease has been described with enhanced ristocetin-induced platelet aggregation and anodal migration of the factor VIII/von Willebrand factor protein (type IIb). We studied two families with this form of von Willebrand's disease and macrothrombocytopenia. We have found that these platelets bind more of the normal and intermediate-sized multimers of the factor VIII/von Willebrand factor than normal platelets. Analysis of the binding data show an increased affinity of these vWd platelets for the factor VIII/von Willebrand factor. These findings are consistent with an increased number of platelet receptors, which, either by their native topography or migration on the platelet surface, bind factor VIII/von Willebrand factor protein with greater affinity than normal platelets, platelets of other vWd patients, and large platelets of other etiologies.

Adolescent↗