Plasminogen activator inhibitor: a regulator of ancrod-induced fibrin deposition in rabbits

Plasma levels of a fast-acting plasminogen activator inhibitor (PAI), which neutralizes both tissue plasminogen activator (t-PA) and urokinase, are markedly increased in endotoxin-treated rabbits. The ability of this inhibitor to prevent the fibrinolysis that occurs after a thrombogenic stimulus was investigated in a rabbit model. Normal and endotoxin-treated male New Zealand rabbits were infused with ancrod, an enzyme that causes noncrosslinked fibrin formation in vivo. Ancrod stimulated t-PA activity by 90% in normal rabbits and caused hypofibrinogenemia but did not increase PAI levels or induce fibrin deposition in target organs. Rabbits injected with endotoxin (10 micrograms/kg) showed an increase in PAI from less than 1 to 32 U/mL 4 hours later. When ancrod was infused at this time, 90% of the rabbits developed renal fibrin thrombi. Fibrin deposition was recorded in 40% of the rabbits that received a lower dose of endotoxin (1.0 microgram/kg) and had a PAI level of 14 U/ml at the time of ancrod infusion 4 hours later. Fibrin deposition did not occur in the endotoxin-treated rabbits that received normal saline. These data suggest that high levels of PAI inhibit fibrinolysis in vivo, thereby promoting fibrin clot deposition following a thrombogenic stimulus.     

Cogan's syndrome with Takayasu's arteritis

Cogan's syndrome may be associated with large-vessel arteritis. We describe a patient with ocular inflammation, sensorineural hearing loss and arm claudication in whom a diagnosis of 'atypical' Cogan's syndrome and Takayasu's arteritis was made. All symptoms resolved with treatment.      

Fractionated total body irradiation and high-dose etoposide as a preparatory regimen for bone marrow transplantation for 99 patients with acute leukemia in first complete remission

Ninety-nine consecutive patients with acute leukemia in first complete remission under age 50 (median age 27 years; age range 1 to 47 years) with a histocompatible sibling donor were treated with fractionated total body irradiation (1,320 cGy) and high-dose etoposide (60 mg/kg) followed by allogeneic bone marrow transplantation. Sixty-one patients were diagnosed with acute myelogenous leukemia (AML), 34 patients with acute lymphoblastic leukemia (ALL), 3 patients with biphenotypic acute leukemia, and 1 patient with acute undifferentiated leukemia. Thirty of the 34 patients with ALL had at least one of the following high-risk factors: age greater than 30, white blood cell count at presentation > 25,000/microL, extramedullary disease, certain chromosomal translocations, or the need for greater than 4 weeks of induction chemotherapy to achieve first complete remission. Cumulative probabilities of disease-free survival and relapse at 3 years were 61% and 12%, respectively, for the 61 patients with AML and 64% and 12%, respectively, for the 34 patients with ALL. By stepwise Cox regression analysis, significant prognostic variables for patients with acute myelogenous leukemia were the presence of acute graft-versus-host disease and increasing age, whereas for patients with acute lymphoblastic leukemia, significant variables were age and the development of cytomegalovirus-associated interstitial pneumonia. Complications related to graft-versus-host disease and relapse of leukemia were the major causes of death.     

Immunologic characterization of a helper T-cell lymphoma

The lymphocytes of a patient with a T-cell non-Hodgkin's lymphoma with peripheral blood involvement and polyclonal hypergammaglobulinemia were characterized in terms of surface markers and immunologic functions. Using the fluorescence-activated cell sorter and employing various monoclonal antibodies against T-cell surface antigens, it was shown that almost all of the patient's peripheral blood lymphocytes were positive for OKT4 and 9.3, antibodies that recognize helper T-cell subset. The circulating lymphoma cells had typical characteristics for T cells; they formed spontaneous rosettes with sheep erythrocytes and stained with the pan-T-cell antibodies 9.6 and 10.2, but did not react with other anti-T-cell monoclonal reagents such as OKT3, UCHT-1, and 3A1. The cells appeared to be mature by the fact that they did not stain with OKT6, and terminal deoxynucleotidyl transferase was undetectable. Functionally, they were able to provide "help" for antibody production, and they could be stimulated to produce moderate amounts of interleukin-2, while unable to proliferate in response to mitogens. Morphologically, some of the lymphocytes showed a deeply cleaved nucleus.     

Expression and functionality of the trkA proto-oncogene product/NGF receptor in undifferentiated hematopoietic cells

The expression of the low-affinity NGF receptor (p75) and the trkA proto-oncogene product was analyzed in a series of human hematopoietic cell lines at protein and RNA levels. We did not detect any form of NGF receptor in cell lines displaying a myelomonocytic phenotype (HL60 and U937). In contrast, cells displaying a more immature erythroleukemic phenotype (TF1 and K562) expressed TrkA in the absence of detectable p75. Scatchard analysis showed a single high-affinity site for NGF (kd = 10(-10) mol/L), with a copy number ranging from 300 to 3,000 sites per cell depending on the studied cell line. In addition, NGF induced autophosphorylation of TrkA and could substitute for granulocyte- monocyte colony-stimulating factor to trigger the proliferation of the TF1 cell line, with a half-maximal signal observed at 50 pmol/L, indicating that p75 is not required for DNA synthesis in this cell line. The physiologic relevance of NGF in early hematopoiesis was confirmed by showing that 12% to 15% of progenitor blood cells from mice treated with 5-fluorouracil expressed TrkA and that these cells could be induced to proliferate and differentiate in response to NGF in association with macrophage colony-stimulating factor. Our study demonstrates for the first time that trkA proto-oncogene expression and activation is not restricted to the nervous system, but is also an important element in early hematopoiesis.     

Prevalence of human T-cell leukemia/lymphoma virus (HTLV) type II infection among high-risk individuals: type-specific identification of HTLVs by polymerase chain reaction

The extent of human T-cell leukemia/lymphoma virus type II (HTLV-II) infection and its rate of spread have been difficult to determine owing to the serological cross-reactivity between HTLV-I and HTLV-II. The present study overcame this problem by directly detecting type-specific proviral sequences by means of the polymerase chain reaction (PCR) and liquid hybridization. Screening was performed on a cohort of primarily white intravenous drug abusers (IVDAs), and individuals of other behaviorally defined risk groups from the New York City area. Eleven percent (19 of 169) of the individuals in these high-risk groups were determined by PCR to have HTLV-II proviral infections. One of these patients displayed an exfoliative erythrodermatitis. Thirteen of the 19 subjects were positive in an HTLV-II enzyme-linked immunosorbent assay (ELISA). The remaining six individuals, although negative in the HTLV- II ELISA, were confirmed as HTLV-II positive by analyzing their DNA with a second HTLV-II-specific primer detector system. Four additional individuals were reactive in the HTLV-II ELISA but were PCR-negative for HTLV-II. PCR analysis for HTLV-I revealed that all four were positive for that virus. Thirty-seven percent (seven of 19) of the HTLV- II PCR-positive subjects were also PCR-positive for HTLV-I, and 84% (16 of 19) of the HTLV-II positive individuals were infected with human immunodeficiency virus (HIV-1). Six individuals were triply infected with HTLV-I, HTLV-II, and HIV-1.     

Subsecond calcium dynamics in ADP- and thrombin-stimulated platelets: a continuous-flow approach using indo-1

The regulation and kinetics (less than 5 seconds) of cytosolic calcium changes ([Ca2+]i) in stimulated blood platelets have been investigated under physiological blood flow conditions. Using a newly-developed continuous-flow approach with indo-1-loaded human platelets, adenosine diphosphate (ADP, 10 mumol/L) and thrombin (5 U/mL) were equally effective in significantly increasing [Ca2+]i by 0.5 seconds. ADP induced a transient [Ca2+]i peak of 1 to 2 mumol/L near 2 seconds, whereas thrombin caused a sustained and larger response. The first phase (less than 2 seconds) was not influenced by a lack of extracellular Ca2+, in contrast to the subsequent [Ca2+]i increase that only reached about 0.7 mumol/L for either ADP or thrombin. The shear rates used in our continuous-flow apparatus were physiological (less than 1,258 sec-1) and only slightly increased the basal [Ca2+]i of 0.1 mumol/L. Platelet aggregation (less than 5 seconds), assessed by single- particle counting, was not altered in platelets loaded with indo-1/AM (2.5 mumol/L).     

The site of the breakpoint within the bcr is a prognostic factor in Philadelphia-positive CML patients [see comments]

The Philadelphia (Ph1) chromosome, characteristic of chronic myelogenous leukemia (CML), arises from a reciprocal translocation between chromosomes 9 and 22. The site of the breakpoint on chromosome 22 is within a small region called the breakpoint cluster region (bcr). We have mapped the breakpoint within the bcr in peripheral blood leukocyte DNA from 22 Ph1-positive CML patients. No correlation between the site of the breakpoint and the clinical phase of the disease was found. However, a striking correlation between the site of the breakpoint and the length of time between presentation and onset of acute phase was observed: on average, patients with a 5' break-point had a fourfold longer chronic phase (median, 203 weeks) than those with a 3' breakpoint (median, 52 weeks).     

Effect of natural killer cells on syngeneic bone marrow: in vitro and in vivo studies demonstrating graft failure due to NK cells in an identical twin treated by bone marrow transplantation

Bone marrow transplantation for severe idiopathic aplastic anemia was undertaken in a patient, using his monozygotic twin brother as the donor. In spite of the use of syngeneic bone marrow, failure of engraftment occurred on two occasions. In vitro studies demonstrated that natural killer (NK) cells from the recipient markedly inhibited the growth of donor bone marrow granulocyte progenitor cells. On a third attempt, successful bone marrow engraftment was achieved following high-dose cyclophosphamide, which has previously been shown to be inhibitory to NK cells. We conclude that NK cell activity may play an important role in bone marrow failure as well as being responsible for at least some cases of aplastic anemia.