Characterization of platelet aggregation induced by the human carcinosarcoma Colo 526: role of platelet activation, tumor cell cytoskeleton and tumor cell plasma membrane.

Tumor cell-platelet interactions have been shown to be involved in the process of metastasis. This study characterizes the aggregation of washed platelets induced by the human uterine carcinosarcoma Colo 526. Ultrastructural studies revealed a two-stage process in which the earliest events were the adhesion and degranulation of individual platelets in contact with the tumor cell membrane. The second stage consisted of a wave of aggregation involving all residual platelets. We found that the first stage was initiated by a factor integral to the tumor cell plasma membrane which acted independently of the tumor cell cytoskeleton or metabolic processes. This factor was found to be a glycoprotein or glycolipid with functionally important sialic acid and N-linked carbohydrate residues. The initial stage was not dependent on platelet activation as neither aspirin nor prostacyclin prevented adhesion or degranulation. The second stage was found to be dependent on platelet activation. These results suggest that platelet aggregation induced by Colo 526 involves a distinctive primary stage which is initiated by a factor on the tumor cell plasma membrane resulting in the degranulation and lysis of individual platelets. This process can occur independently of platelet activation or aggregation and thus may have some relevance to the clinical use of platelet antagonists as antimetastatic agents.

Hematologic abnormalities occur in both cortical and lacunar infarction.

BACKGROUND AND PURPOSE: Primary hematologic abnormalities are a rare but established cause of ischemic stroke. In addition, activation of hemostatic parameters is often present during the acute phase of stroke. However, it is uncertain whether these abnormalities occur in both cortical and lacunar infarction; this study aimed to further assess this issue. METHODS: Hematologic parameters (prothrombin, activated partial thromboplastin, thrombin clotting, and euglobulin lysis times; and fibrinogen, fibrinopeptide A, antithrombin III, protein C, protein S, and plasminogen levels) were measured in 19 patients within 48 hours of the onset of acute cerebral infarction. These patients included 10 with cortical infarcts and 9 with lacunar infarcts, as determined by standard clinical and radiological criteria. RESULTS: Five patients with lacunar infarction and 7 patients with cortical infarction demonstrated raised fibrinopeptide A levels, indicating enhanced thrombin activity. Fibrinolysis, assessed by the euglobulin lysis time, was impaired in 6 of 9 patients with lacunar infarction and in 2 of 10 patients with cortical infarction. Lupus anticoagulants were detected in 3 patients with lacunar infarction and in 1 patient with cortical infarction. Three patients in each group displayed decreased antithrombin III function, and 1 patient with a lacunar infarction had a low protein C level. CONCLUSIONS: Primary hematologic disorders and secondary hemostatic derangements may occur in patients with either cortical or lacunar infarction.

An evaluation of the Sysmex NE-8000 hematology analyzer.

The Sysmex NE-8000 is a new, fully automated hematology analyzer capable of providing a five-part white blood cell differential count and identifying abnormal specimens. This instrument was evaluated on 5,000 consecutive blood specimens and compared to the Coulter S Plus-IV analyzer and manual differential cell counts to determine the efficacy of its five-cell differential and screening capabilities. There was a high correlation between the commercial counters for the standard parameters, white blood cell count, red blood cell count, hemoglobin level, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration, and platelet count (r greater than 0.95), except for the mean corpuscular hemoglobin concentration (r = 0.51), for which the NE-8000 was considered the more accurate measurement. Precision and linearity studies were excellent. The white blood cell count, red blood cell count, hemoglobin level, and platelet count were reproducible on specimens stored at 4 degrees C or room temperature for 72 hours and the differential counts were reproducible for 12 hours. The correlations between automated and manual counts for neutrophils, eosinophils, basophils, and lymphocytes were excellent: r = 0.912, 0.945, 0.332, and 0.964, respectively. The monocyte correlation improved with software modification from 0.306 to 0.801. The NE-8000 gave accurate and reproducible differential counts for neutrophils, lymphocytes, and monocytes on specimens with white blood cell counts as low as 0.6 x 10(9)/1. The ability of the instrument to 'flag' abnormal specimens was excellent. The false-positive rate on normal samples was 1.8%, and the false-negative rate on known abnormal samples was 0.3%, due only to nonrecognition of a mild left shift. The identification of specific abnormalities was less precise. The NE-8000 is a powerful hematology analyzer that can perform a five-part white blood cell differential count accurately for a wide range of WBCs and reliably indicate abnormal specimens. It is an excellent screening tool for distinguishing between normal and abnormal specimens and identifying those that require microscopy. Its reliability significantly reduces the need for manual film examination.