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  • 1
    Publication Date: 1984-06-01
    Description: We have studied the role of factor VIII-von Willebrand factor (FVIII- vWF) in both platelet adherence to subendothelium and ristocetin- induced platelet aggregation using monoclonal antibodies to human FVIII- vWF. Twenty-five monoclonal antibodies were obtained, two of which were directed to the factor VIII moiety of FVIII-vWF; one of these two completely inhibited the procoagulant activity (FVIII:C). The remaining 23 monoclonal antibodies were directed to the von Willebrand factor moiety of FVIII-vWF. The ability of the latter monoclonal antibodies to inhibit platelet adherence to arterial subendothelium was investigated with a perfusion model. According to the number of platelets adhering to the subendothelium, three groups of monoclonal antibodies could be discerned: (A) antibodies not affecting platelet adherence; (B) antibodies that inhibited platelet adherence to the level as observed when von Willebrand's disease plasma was tested; and (C) antibodies that completely inhibited both platelet adherence to subendothelium and ristocetin-induced platelet aggregation. The two antibodies present in group C competed for the same or closely related epitope(s) present on FVIII-vWF. These results demonstrate that a domain is present on the FVIII-vWF molecule that is associated both with ristocetin-induced aggregation and with the ability of FVIII-vWF to support platelet adherence to the subendothelium. Based on these observations, it is concluded that ristocetin-induced binding of FVIII-vWF to platelets reflects, at least in part, a physiologic mechanism regulating the function of FVIII-vWF in primary hemostasis.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 2
    Publication Date: 1984-10-01
    Description: Restriction endonuclease mapping defined a partial deletion of about 1.35 kb in the beta-globin gene of a black American patient with hemoglobin S-beta zero-thalassemia and in his uncle with a beta zero- thalassemia trait. The 5′ endpoint of the deletion is about 600 bases upstream from the cap site, and the 3′ endpoint lies within about 500 bases from the 5 splice junction of the second intervening sequence. The deletion is different from that of a previously reported Indian beta zero-thalassemia allele, where 0.6 kb is deleted at the 3′ end of the beta-globin gene.
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  • 3
    Publication Date: 1982-12-01
    Description: Two leukemic cell lines (697 and 207) were established from bone marrow cells obtained from children with ALL in relapse. These cell lines were positive for the common-ALL antigen (CALLA), the HLA-DR (i.e., Ia-like) antigen, and for cytoplasmic and surface IgM heavy chains. The lines were negative for other immunoglobulin heavy chains and light chains. The lines had elevated levels of terminal deoxynucleotidyl transferase enzyme and expressed surface antigens found on normal myeloid- macrophage cells (MMA) and on natural killer cells (HNK-1). A minority of cells in line 207 expressed the T-1, T-6, and Leu-1 antigens as detected by monoclonal antibodies. Line 697 was positive for Epstein- Barr virus (EBV), while line 207 did not possess EBV. Line 697 carried a marker chromosome (identified as a translocation between chromosomes 7 and 19), which was also patient's fresh leukemic cells. The leukemic origin of the cell lines was further indicated by their morphological, cytochemical, and immunologic similarity to the patients' leukemic cells. Phenotypically, both cell lines appear to be arrested in a transitional stage of development between pre-B and B cells and express surface antigens usually found on normal and fresh leukemic cells of non-B-cell lineages.
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  • 4
    Publication Date: 1983-08-01
    Description: Actin is an important cytoskeletal protein; new actin synthesis occurs during differentiation of many motile cells. To better understand the process of myeloid maturation, the change in actin content during induced maturation of HL-60 human promyelocytic leukemia cells was studied. HL-60 cells induced toward myeloid maturation by a 5-day exposure to dimethylformamide showed an 86% increase in a 43,000 mol wt protein comigrating with rabbit muscle actin on dodecyl sulfate polyacrylamide gels. To further demonstrate that this was an increase in actin content, the total actin content of lysed HL-60 cells was measured by the ability of actin to inhibit DNAase I. Using this assay, actin content of HL-60 cells increased 96% during induced differentiation. The amount of incorporation of 3H-leucine into actin doubled after a 5-day exposure to dimethylformamide, suggesting the increase in actin was due primarily to new synthesis. Total new protein synthesis increased 2–7-fold during differentiation. Additional analysis of polyacrylamide gels showed increased quantities and new synthesis of a high molecular weight protein comigrating with rabbit muscle myosin. This study shows that actin content increases during myeloid maturation. It also demonstrates that the HL-60 cell line is a useful model to study both functional and biochemical events during human myeloid differentiation.
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  • 5
    Publication Date: 1982-05-01
    Description: Time-lapse videotape recordings of polymorphonuclear leukocytes (PMNs) from clot preparations were used to quantify the locomotive behavior of individual PMNs from normal subjects. Tracings derived from the videotapes allow one to quantify multiple parameters of the locomotive behavior of PMNs--direction, distance, rate, and angle of turn. The results obtained are reproducible from subject-to-subject and from preparation-to-preparation. The method allows the investigator to record the locomotive behavior of 100 cells simultaneously within a 5- min period and analyze the recording as time permits. We utilized this technique to compare the locomotive behavior of slow and fast PMNs (arbitrarily defined as cells that move less than or equal to 7.0 micrometer/min and greater than 7.0 micrometer/min mean rate of locomotion, respectively). The studies show that slow and fast PMNs, thus defined, differ not only in mean rate of locomotion but also in their rate of locomotion during periods of active locomotion, in the number of periods of inactivity/PMN/5 min (slow = 1.65 +/- 0.31; fast = 0.36 +/- 0.12), and in their turning behavior as measured by angle of turn (slow = 92 degrees +/- 39 degrees; fast = 39 degrees +/- 35 degrees). These results show that human PMNs from clot preparations are remarkably heterogeneous in their locomotive behavior, and the results suggest this heterogeneity is due to endogenous differences within cells.
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  • 6
    Publication Date: 1981-03-01
    Description: Treatment of human PMNs with cytochalasins (CE, CD, CB, and H2CB) results in alteration of cell morphology and inhibition of cell motility. Morphological changes are similar to those reported for nonamoeboid fibroblasts--rounding, zeiosis, and arborization. Mean cell velocity of PMNs, as measured by quantitative analysis of time-lapse videotape recordings, was reduced to 0.1 micron/min (control, 7.3 +/- 4.2 micron/min). Phagocytosis by PMNs, as measured by phagocytosis of latex beads, was inhibited by 75%. The relative potency of the cytochalasins for inducing morphological change or for inhibiting locomotion and phagocytosis is similar to their relative potencies for affecting non-amoeboid cells: CE greater than CD greater than CB greater than or equal to H2CB. Quantitative binding of 3H-CB to purified PMNs under equilibrium conditions reveal two types of specific CB binding sites: high-affinity sites (KD approximately 3 x 10(-7) M, 3 x 10(6) sites/cell) and low affinity sites (KD approximately 2 x 10(-6) M). The relative affinities of the cytochalasins for the high-affinity and low-affinity CB binding sites parallel their relative potencies for inducing biologic effects (i.e. CE greater than CD greater than CB greater than or equal to H2CB).
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  • 7
    Publication Date: 1984-08-01
    Description: In a patient with Richter's syndrome, the chronic lymphocytic leukemia (CLL) expressed lambda, mu, and delta immunoglobulin (lg) chains and the non-Hodgkin lymphoma (NHL) kappa, mu, and delta lg chains. The difference in lg light chain expression suggests that the CLL and NHL are independent malignancies, or that the oncogenic event occurred in a B cell differentiation stage after the heavy chain gene rearrangements but before the selection of the light chain. Analysis of DNA by Southern blotting revealed that the lg heavy chain genes of the two malignancies were rearranged in a different way. We therefore conclude that in this patient the NHL cannot be regarded as a progression of the CLL but should most likely be considered as an independent B cell malignancy, which arose in a susceptible host.
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  • 8
    Publication Date: 1981-03-01
    Description: Treatment of human PMNs with cytochalasins (CE, CD, CB, and H2CB) results in alteration of cell morphology and inhibition of cell motility. Morphological changes are similar to those reported for nonamoeboid fibroblasts--rounding, zeiosis, and arborization. Mean cell velocity of PMNs, as measured by quantitative analysis of time-lapse videotape recordings, was reduced to 0.1 micron/min (control, 7.3 +/- 4.2 micron/min). Phagocytosis by PMNs, as measured by phagocytosis of latex beads, was inhibited by 75%. The relative potency of the cytochalasins for inducing morphological change or for inhibiting locomotion and phagocytosis is similar to their relative potencies for affecting non-amoeboid cells: CE greater than CD greater than CB greater than or equal to H2CB. Quantitative binding of 3H-CB to purified PMNs under equilibrium conditions reveal two types of specific CB binding sites: high-affinity sites (KD approximately 3 x 10(-7) M, 3 x 10(6) sites/cell) and low affinity sites (KD approximately 2 x 10(-6) M). The relative affinities of the cytochalasins for the high-affinity and low-affinity CB binding sites parallel their relative potencies for inducing biologic effects (i.e. CE greater than CD greater than CB greater than or equal to H2CB).
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  • 9
    Publication Date: 1983-08-01
    Description: Actin is an important cytoskeletal protein; new actin synthesis occurs during differentiation of many motile cells. To better understand the process of myeloid maturation, the change in actin content during induced maturation of HL-60 human promyelocytic leukemia cells was studied. HL-60 cells induced toward myeloid maturation by a 5-day exposure to dimethylformamide showed an 86% increase in a 43,000 mol wt protein comigrating with rabbit muscle actin on dodecyl sulfate polyacrylamide gels. To further demonstrate that this was an increase in actin content, the total actin content of lysed HL-60 cells was measured by the ability of actin to inhibit DNAase I. Using this assay, actin content of HL-60 cells increased 96% during induced differentiation. The amount of incorporation of 3H-leucine into actin doubled after a 5-day exposure to dimethylformamide, suggesting the increase in actin was due primarily to new synthesis. Total new protein synthesis increased 2–7-fold during differentiation. Additional analysis of polyacrylamide gels showed increased quantities and new synthesis of a high molecular weight protein comigrating with rabbit muscle myosin. This study shows that actin content increases during myeloid maturation. It also demonstrates that the HL-60 cell line is a useful model to study both functional and biochemical events during human myeloid differentiation.
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  • 10
    Publication Date: 1984-05-01
    Description: Restriction endonuclease mapping with alpha and zeta-globin gene probes showed differences between the alpha-thalassemia-1 (alpha-thal-1) condition in two patients with HbH disease. One patient had the rare black type of alpha-thal-1 together with alpha-thal-2 and HbS heterozygosities. The second patient was a Laotian child with HbE, Hb Constant Spring (alpha-thal-2), and alpha-thal-1 heterozygosities. The diagnoses were based on clinical, hematologic, and biochemical data. Whereas DNA fragments hybridizing to a zeta-probe were obtained from the Laotian type of alpha-thal-1, neither alpha nor zeta-gene fragments could be identified deriving from the black type of alpha-thal-1. Therefore, the black type of alpha-thal-1 is associated with a deletion of the entire zeta 2-psi zeta-psi alpha-alpha 2-alpha 1 gene complex and can be considered a zeta alpha-thal-1. It is likely that homozygosity for such a condition will lead to embryonic wastage, explaining the absence of hydrops fetalis in blacks.
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