Enhanced platelet adherence and aggregation in Chagas' disease: a potential pathogenic mechanism for cardiomyopathy

Spasm and thrombosis of the coronary microcirculation has been implicated in the pathogenesis of the cardiomyopathy of Chagas' disease. We demonstrate that increases in platelet adherence and aggregation accompany Trypanosoma cruzi infection and may contribute to the observed microvascular pathology. Scanning electron microscopy and radiolabeled platelets studies revealed that platelet adherence to T. cruzi-infected human endothelial cells was significantly increased when compared to controls (P = 0.024). In in vitro experiments, we determined the influence of infection on prostacyclin production, a marker of endothelial cell perturbation. The basal levels of 6-keto-prostaglandin F1 alpha was significantly greater in the supernatant of infected endothelial cells than in those of uninfected endothelial cells (P less than 0.05). The influence of infection was assessed on platelet aggregation at days 5 and 12 post-infection in A/J mice. Platelets from T. cruzi-infected mice were 2-6-fold more sensitive to aggregation induced by adenosine diphosphate and sodium arachidonate than controls. Thromboxane B2 levels in the plasma of infected mice were greater than controls. These data support the hypothesis that heightened platelet reactivity and endothelial cell dysfunction are associated with acute Chagas' disease and may cause coronary microvascular spasm and/or occlusion.

Flow cytometric DNA analysis of corneal epithelium

We have modified an existing technique in order to perform DNA analysis by flow cytometry (FCM) of corneal epithelium from the mouse, rat, chicken, rabbit, and human. This protocol permitted an investigation of human corneal scrapings from several categories: normal, aphakic bullous keratopathy (ABK), keratoconus (KC), Fuch's dystrophy, edema, epithelial dysplasia, and lipid degeneration. No abnormal characteristic cell-kinetic profile was detected when averaged DNA histograms were compared statistically between the normal and either ABK, KC, edema, or Fuch's dystrophy groups. Abnormal DNA histograms were recorded for cell samples that were taken 1) from three individuals who had epithelial dysplasia and 2) from one individual diagnosed with lipid degeneration. The former condition was characterized by histograms that had a subpopulation of cells with an aneuploid amount of DNA or had higher than normal percentages of cells in the S and G2 + M phases of the cell cycle. Corneal cells from the patient who had lipid degeneration had an abnormally high percentage of cells in the G2 + M phases of the cell cycle. The availability of accurate DNA flow cytometric analysis of corneal epithelium allows further studies on this issue from both experimental and clinical situations.

Clinical utility of serum tests for iron deficiency in hospitalized patients

Serum iron and ferritin measurements lack the requisite sensitivity and/or specificity to accurately diagnose iron deficiency. To determine their utility in hospitalized patients, the authors compared the results of these tests with the presence of stainable iron in bone marrow aspirates of 301 patients. Forty (13.3%) had absent marrow iron. The serum diagnosis of iron deficiency was accepted on the basis of the following: iron less than 11 mumol/L, total iron-binding capacity (TIBC) greater than 45 mumol/L, transferrin saturation (%Sat) less than 0.20, and ferritin less than 13 micrograms/L for females and less than 25 micrograms/L for males. Using these criteria, iron deficiency was correctly diagnosed by serum iron in 41%, TIBC in 84%, %Sat in 50%, and ferritin in 90% of the patients. The serum ferritin is clearly the only useful serum test for diagnosing iron deficiency in hospitalized patients but is limited by a low sensitivity. The bone marrow examination is the most sensitive test for diagnosing iron deficiency in hospitalized patients.

Hematologic manifestations in pediatric HIV infection: severe anemia as a prognostic factor

The hematologic profile of 100 symptomatic children infected by the human immunodeficiency virus (HIV) was evaluated and compared to HIV uninfected infants with transplacentally acquired maternal anti-HIV antibodies, and to HIV-negative infants born to i.v. drug-abusing HIV uninfected mothers. Anemia was present in 94% of HIV-infected infants and was a major predictor of disease progression. In 91% of patients having a hematocrit (HcT) less than 25%, the disease course was rapidly fatal. Leukopenia and thrombocytopenia occurred in 47 and 33% of HIV infected patients, respectively. Neutropenia was most severe in children with opportunistic infections. There was no evidence of suppression of any component of hematopoiesis by passively acquired antibodies to HIV.

Bleeding time. A guide to its diagnostic and clinical utility

Although the bleeding time is the most widely used clinical test employed to assess platelet function, its indications are poorly defined. The test is commonly used as a preoperative screen to predict hemorrhage, but the data supporting this indication are contradictory at best. In this review we highlight the physiologic basis for the bleeding time and survey the literature for data supporting the valid indications for its use. The bleeding time is a useful test for assessing platelet function in patients with hemorrhagic disorders. Its utility in providing helpful clinical information in patients who do not have a known bleeding diathesis by history is minimal. Specific recommendations regarding the rational use of the bleeding time for the preoperative evaluation of patients are presented.

A human adult Wilms' tumor. Histologic, ultrastructural, and cytogenetic analysis

The cytogenetic, histologic, and electron microscopic studies of an adult patient with Wilms' tumor are presented. Wilms' tumor (nephroblastoma) is a common renal tumor of childhood but is extremely rare in people over 15 years old. The histologic analysis of the patient's tumor, including both light and electron microscopic analysis, indicated that this tumor satisfies the histologic criteria for an adult Wilms' tumor, namely, blastemic cells that are immature renal parenchymal cells, embryonic tubular structures, and a scanty stromal component consisting of loosely arranged spindle cells. The tumor showed several ultrastructural features characteristic of adult Wilms' tumor, namely, markedly elongated mitochondria, autophagic vacuoles, and intracytoplasmic filaments. Karyotypic analysis was performed on the patient's peripheral leukocytes and tumor cells. The leukocytes showed no significant increase in gaps and breaks, and the patient appears to have a normal male karyotype. Some interesting chromosomal anomalies were observed in the cultured tumor cells: at least one chromosome 13, both chromosomes 22, and the X chromosome are missing, three markers are present, and there is a possible deletion of 12p.

In vitro antiproliferative activity of 4-substituted 2-(2-hydroxyphenyl)thiazolines on murine leukemia cells

Two previously synthesized and two structurally novel thiazoline iron chelators are described. N4-Benzyl-N1,N8-bis[[2-(2-hydroxyphenyl)thiazolin-4-yl]carbonyl] homospermidine (5) proved to be the most potent antiproliferative and cytocidal compound in the series with in vitro IC50 values of 3 and 1 microM on L1210 and P388 murine cell lines. The N4-acetyl analogue 7 was considerably less active than 5 with IC50 and cell viability values that were similar to those of the structurally simple thiazolines 2 and 3. The antiproliferative activity of 3 and 7 could be substantially reduced or ablated by delivery to cell suspensions as a 1:1 molar mixture with FeCl3, while the activity of 5 was unaffected by Fe(III) chelation. As expected, 3 induced a G1/S cell cycle block at the 100 microM block consistent with interference with DNA synthesis while 10 microM 5 did not affect L1210 cell cycle distribution. Tritiated thymidine incorporation studies confirmed that 5 was incapable of interfering with DNA synthesis at concentrations below 40 microM. Alkaline elution studies indicate that 5 does not cause DNA strand breaks in vitro at concentrations of 10 microM. The N4-benzyl group of 5 appears to impart in vitro potency as the N4-acetyl analogue 7 lacks comparable in vitro antiproliferative and cytocidal activity.

Modification of a trypsin-detergent method for DNA flow cytometry of human epidermis

An existing technique (Vindelov et al. Cytometry 3:323, 1983) has been modified for DNA flow cytometry of human epidermis obtained from 2 to 3 mm punch biopsies. By varying the length of time of digestion of the epidermal disc by trypsin from 5 to 70 min a controlled release of keratinocytes occurred beginning with the stratum basale and proceeding toward, but not including, the superficial layer of the epidermis, the stratum corneum.

Thrombocytopenia and human immunodeficiency virus in children

Thrombocytopenia occurs in 13% of children with symptomatic human immunodeficiency virus (HIV) infection. The clinical and laboratory course of 19 children infected with HIV with thrombocytopenia is described. Bone marrow aspirates showed normal to increased numbers of megakaryocytes. Levels of antiplatelet antibodies were increased in 80% of the children and circulating immune complexes were found in 74%. Clinically significant hemorrhage leading to anemia occurred in five patients, and CNS bleeding led to a fatal outcome in an additional three children. Spontaneous remission of thrombocytopenia occurred in three of the 19 subjects. High-dose IV gamma-globulin was effective in increasing the platelet counts of six of 15 patients (40%) but resulted in a sustained remission in only one subject. Oral prednisone was effective in increasing the platelet count of two thirds of those whose platelet counts could not be controlled by IV gamma-globulin. Bleeding manifestations were eliminated in all patients whose platelet counts increased significantly. Of the 11 children whose counts increased either spontaneously or as a result of therapy, eight remain alive (72%). In contrast, all of the eight patients whose platelet counts did not improve have died. Thrombocytopenia in children with HIV disease is engendered by immune mechanisms and is a major cause of morbidity and mortality. High-dose IV gamma-globulin and/or corticosteroids are temporarily effective in increasing the platelet count and reducing bleeding in about half of thrombocytopenic patients and are recommended for use. The ability to respond to therapy correlates with improved survival.

Acquired circulating anticoagulants in children with acquired immunodeficiency syndrome

The mechanism underlying the prolonged activated partial thromboplastin time (APTT) seen in some pediatric patients with acquired immunodeficiency syndrome (AIDS) and opportunistic infections was studied. A circulating inhibitor of coagulation was demonstrated in three patients. The inhibitor appears to be an immunoglobulin that interferes with some of the phospolipid-dependent coagulation reactions of the intrinsic pathway. This "AIDS anticoagulant" does not predispose the patient to clinical bleeding despite its ability to cause a marked prolongation of the APTT. As such, careful laboratory diagnosis of the cause of abnormal coagulation test results is necessary for children with AIDS.

In vitro antiproliferative activity of 2'-(2-hydroxyphenyl)-2'-thiazoline-4'-carboxylic acid and its methyl ester on L1210 and P388 murine neoplasms

The activity of three iron chelators, methyl [2'-(2-hydroxyphenyl)-2'-thiazoline-4'-carboxylate] (MTL); 2'-(2-hydroxyphenyl)-2'-thiazoline-4'-carboxylic acid (TFAL); and 2-hydroxyphenyl-imido-ethyl-ether (Imidate), regarding antiproliferative, cytocidal, and cell-cycle effects are reported and compared with hydroxyurea (HU). In vitro, against L1210 and P388 murine neoplasms, MTL and TFAL displayed substantially greater antiproliferative activity than HU, although Imidate displayed no appreciable activity. MTL also induced a statistically more complete G1/S cell-boundary block than did HU at equimolar concentrations (100 microM). The IC50 values produced by MTL and TFAL were low enough (less than or equal to 20 microM) to warrant further testing of these chelators as potential antineoplastic agents.

P. falciparum infected erythrocytes are capable of endocytosis

P. falciparum, an intraerythrocytic parasite, obtains nourishment primarily through phagocytosis of the host cytosol but also through the incorporation of extracellular small molecules which enter through the parasitized red cell's membrane via pores. Normal mature erythrocytes are incapable of endocytosis. Several lines of evidence suggest that extracellular large molecules may be taken up when the mature red cell is parasitized by P. falciparum, but direct evidence has been lacking. We now report the use of ferritin, an electron dense protein, to demonstrate endocytosis in P. falciparum infected red cells. Parasitized red cells incubated with ferritin internalize that macromolecule as demonstrated by electron microscopy. While normal red cells incubated with ferritin took up none of the tracer molecule, parasitized red cells internalized substantial amounts. In addition both ferritin and apoferritin inhibited the growth of P. falciparum in a dose dependent fashion, again indicating endocytosis of a macromolecule. These data indicate that P. falciparum can somehow stimulate the mature erythrocyte to engage in endocytosis. We also note that both infected and non-infected red cells in a culture in which P. falciparum is growing become abnormally sticky for ferritin. Moreover, parasitized red cells bind I125-transferrin while non-parasitized erythrocytes do not. These observations suggest that a soluble parasite product alters the red cell membrane in a non-global manner, causing selective effects in relation to different proteins.

Comparative immunochemical and structural similarities of five stress proteins from various tissue types

1. Incorporation of radioactive phosphate or leucine by stress proteins from rodent lymphoma, submaxillary and liver nuclei were observed in two-dimensional gels following chemical and environmental stress. 2. The stress proteins were isolated from second-dimension gels and their similarities compared. Mol. wt determinations, immunochemical blotting and protease V8 peptide mapping confirmed the identical nature of the stress proteins possessing identical Mr, but from diverse tissue types. 3. These data imply that highly similar stress proteins exist in diverse tissues, are conserved during evolution, and possess some elemental and essential function.

The turnover of radiolabeled nuclear proteins in rats exposed to environmental and chemical stress

Exposure to a 12 h light/12 h dark (L/D) cycle for 1 month, followed by reversal to a 12 h D/12 h L (D/L) cycle stimulated within 18 h the incorporation of [3H]leucine and [32P]orthophosphoric acid into new proteins (130-25 kDa) in the G0 phase of the cell cycle of the non-regenerating and regenerating rat liver as observed in two-dimensional gel autoradiograms. Six additional proteins from the rat submaxillary gland (130-20 kDa) revealed labeling with 32P within 3 h following combined administration of isoproterenol and sodium arsenite. Labeling disappeared within 7 days for all stressed proteins.

A new assay for quantifying human reticulocytes

The authors describe a new method for quantitative reticulocyte analysis. The assay uses a conventional clinical blood cell analyzer to size a patient's red blood cell neocyte population, which relates to the reticulocyte fraction in a linear fashion. Blood is layered atop Stractan (arabino-galactan polysaccharide) and centrifuged for 30 minutes at 1,500 X g. This density medium fractionation process enriches the Stractan layer with neocytes by up to 20-fold as determined by G6PD enzyme analysis. The mean corpuscular volume (MCV) of the red blood cells partitioning in the Stractan layer and the starting whole blood is then measured. The ratio of the two MCV measurements is then related to the reticulocyte percentage by a standard curve. In 93 patients, the derived MCV ratio was linearly correlated with manual reticulocyte counts (r = 0.96/slope = 0.99). Agreement of results obtained for single samples was within 0.2%. The assay's within-run and between-run precision is excellent (coefficient of variation less than 1%). The assay provides data on the percentage of reticulocytes in whole blood with an accuracy and precision that is at least 20 times greater than conventional microscopic technics.

Biological time and the effects of hydroxyurea on DNA synthetic activity of bone marrow and tumor cells in mice bearing the Ehrlich ascites carcinoma

The objective of this experiment was to attempt to induce, with hydroxyurea (HU), significant quantitative differences in the level of DNA-synthetic activity (DNA-SA) between a neoplastic cell population (the Ehrlich ascites carcinoma or EAC) and bone marrow in the same animal. Mice bearing a 5-day-old EAC were standardized to and kept on an LD 12:12 cycle (light 0600-1800 hr). They were treated with 500 mg/kg HU at 0500 hr (23 hr after lights on, or HALO) or at 1700 hr (11 HALO). DNA-SA was determined by liquid scintillation counting of 3H-thymidine incorporation into chemically isolated DNA. DNA-SA in bone marrow and EAC cells was monitored over the next 60 hr with subgroups of ten mice each killed every 3 hr beginning 3 hr after treatment with HU. The circadian system of the host influenced the response of the bone marrow to HU; i.e., the response to HU administered at 0500 hr was different both qualitatively and quantitatively from that for HU given at 1700 hr. Comparisons of DNA-SA in bone marrow and EAC from the same animal revealed time points after treatment with HU when DNA-SA in the EAC was high, but DNA-SA in bone marrow was low. These differences in the level of DNA-SA between a tumor cell population and bone marrow should be of therapeutic value; i.e., executor doses of anti-DNA-SA drugs such as cytosine arabinoside could be given at that point in time after treatment with HU when DNA-SA in the tumor was high, but DNA-SA in the bone marrow was low.

The H*1 hematology analyzer. Its performance characteristics and value in the diagnosis of infectious disease

The performance characteristics and the value of data provided by the H*1 Automated Blood Cell Analyzer in the diagnosis of infectious disease are assessed. Data produced by the machine are precise over a wide range of complete blood cell counts and differential white blood cell (WBC) parameters. It is capable of accurately quantifying WBCs greater than 4000/mm3 (4 X 10(9)/L); red blood cells (RBCs), greater than 2.5 X 10(6)/mm3 (2.5 X 10(12)/L); and platelets greater than 1 X 10(3)/mm3 (1 X 10(9)/L). There is good agreement between the neutrophils and lymphocytes quantified by the standard microscopic count and the automated system; however, cells that are generally present in low incidence, namely, monocytes, basophils, and eosinophils, are less well correlated. The microscopic band cell count provides the greatest test efficiency in the diagnosis of infection. None of the unique parameters generated by the H*1 differential analyzer proved to have neither a test efficiency nor a diagnostic index greater than that of the absolute WBC count in the diagnosis of infection. The "left shift" in the leukocyte differential count as detected by the H*1 relates poorly to the presence of band neutrophils in the specimen. It is concluded that the state-of-the-art automated leukocyte differential count can dramatically reduce workload, but offers no advantage over the traditional differential WBC count in the diagnosis of infectious disease. Its potential value in the diagnosis of other conditions, particularly hematologic diseases, and in the sequential monitoring of infections in individual patients were not addressed by the present study.

Retinoic acid induction of stress proteins in fetal mouse limb buds

Retinoic acid (RA) is teratogenic in rodent embryos. Several teratogens have been shown to induce the synthesis of a subset of heat shock proteins (stress proteins) in Drosophila. To determine if RA induces the synthesis of these proteins in rodent embryos, pregnant ICR mice were dosed with 100 mg/kg RA on Day 11 of gestation. Forelimb buds were removed from embryos 2.5 hr post-RA-treatment and nuclei were isolated, stained, and sorted from stages of the cell cycle. Nuclear proteins were extracted and analyzed by two-dimensional polyacrylamide gel electrophoresis. Nuclear proteins with molecular weights of approximately 84 and 25 kDa were synthesized in embryos in the G0 + G1 phase after pregnant dams were treated with RA. Isoelectric points, molecular weights, immunochemical blotting, and polypeptide mapping demonstrated that these proteins are indistinguishable from stress proteins isolated under a variety of conditions from rat submaxillary glands and mouse lymphoma cells. These results suggest that treatment with RA induces the synthesis of a subset of stress proteins; the role of these proteins in the teratogenic effects of RA is not known.

Stimulation by cAMP of erythropoietin secretion by an established human renal carcinoma cell line

We used our recently reported stable, transformed human renal carcinoma cell line as a model system to study the role of 3',5'-adenosine monophosphate (cAMP) in erythropoietin secretion. The erythropoietin produced by these cells is both biologically active and immunologically cross-reactive with purified native human hormone in our radioimmunoassay. Erythropoietin release by these renal carcinoma cells appears to be stimulated by cAMP as well as by the phosphodiesterase inhibitor 3-isobutyl-1-methyl-xanthine (MIX). The response to cAMP involves a rapid and enhanced release of hormone, which occurred within 30 minutes of exposure of the cells to the effector and continued for at least 4 hours. Intracellular erythropoietin was higher in the control cultures than in the cells treated with cAMP, suggesting that cAMP stimulates the release of a storage pool of hormone. The ability of cAMP and MIX to elicit the release of erythropoietin suggests that a cAMP-mediated mechanism is involved in the release of this hormone.

Cell cycle-specific effects of sodium arsenite and hyperthermic exposure on incorporation of radioactive leucine and phosphate by stress proteins from mouse lymphoma cell nuclei

Cultured mouse lymphoma cells incorporated [3H]leucine and [32P]phosphate into nuclear stress proteins within 3 h after exposure to either elevated temperature (45 degrees C) or sodium arsenite. Radiolabeled proteins were detected by autoradiography after two-dimensional polyacrylamide gel electrophoresis. To determine the cell cycle stage specificity of labeling, nuclei were isolated and sorted into two cell cycle phases using a fluorescent activated cell sorter. After either heat shock or sodium arsenite treatment, the majority of [3H]leucine incorporation into stress proteins occurred during the G0 + G1 phase with minimal labeling in the G2 phase. On the other hand, 32P labeling of stress proteins occurred in both the G0 + G1 and G2 phases after exposure to sodium arsenite, while incorporation of 32P was limited after heat stress. Following sodium arsenite treatment, a distinct set of four stress proteins (80-84 kDa) was detected with [3H]leucine only in G0 + G1 phase, but with [32P]phosphate these stress proteins were labeled in both G0 + G1 and G2. There was differential [32P]phosphate labeling between proteins of the 80-84 kDa set during cell cycling. Individual proteins of this set were isolated from gel plugs after sodium arsenite or heat-shock treatment. Coelectrophoresis of proteins from the two treatment groups showed that they had similar electrophoretic mobilities. All four proteins of the 80-84 kDa set (sodium arsenite induced) possessed similar polypeptide maps after digestion with V8 protease. Cytofluorometric analysis demonstrated a reduction in the number of nuclei in both S and G2 phases of the cell cycle two h after heat shock, but not following sodium arsenite treatment. However, there was a significant depression in the number of nuclei in S and G2 4 h after exposure to sodium arsenite and very modest labeling with 32P of stress proteins was observed at this time.

The clinical utility of the leukocyte differential in emergency medicine

Leukocyte differentials from 468 emergency room patients were assessed for clinical value by determining their associations with diagnosis, disposition, therapy, and prognosis. The test efficiency of an elevated band count as an indicator of infectious or inflammatory disease is 86%. However, all but 2 of the 99 patients in this disease category had additional indicators of inflammation, including elevated temperatures and/or white blood cell (WBC) counts. The band count lacks utility beyond this limited function. The remaining parameters of the differential count correlate poorly with all diagnostic subsets. The use of antibiotics correlates well with fever and WBC count (r = 0.95) and less well with the differential count, bands (r = 0.85), and granulocytes (r = 0.5). Elevations in the total WBC count and the band count are each associated with an increased likelihood of hospitalization. However, in the absence of leukocytosis, an elevated band count was instrumental in suggesting admission for only one patient. The patient's outcome correlates poorly with the total WBC and differential count. It is concluded that most leukocyte differentials performed for emergency room patients provide information that is no more clinically significant than that obtained from the medical history, physical examination, and absolute leukocyte count.

The preoperative bleeding time as a predictor of postoperative hemorrhage after cardiopulmonary bypass

To determine whether the preoperative bleeding time, the most reliable indicator of in vivo platelet dysfunction, can prognosticate excessive postoperative hemorrhage and, hence, the need for infusion of platelet concentrations, we studied blood loss versus bleeding time in 43 patients undergoing coronary bypass grafting. There was no correlation between bleeding time and either fall in hemoglobin level (r = 0.04) or chest tube drainage (r = 0.004). In addition, bleeding time did not correlate with the number of units of platelet concentrate (r = 0.12) or packed red cells (r = 0.2) infused. The bleeding time, which has been recommended as an essential screening test before all cardiopulmonary bypass procedures, need not be performed as a preoperative screen in otherwise healthy patients with no history of bleeding abnormalities and a normal coagulation profile.

Volumetric erythrocyte macrocytosis induced by hydroxyurea

An atypical form of macrocytosis termed volumetric macrocytosis is described. In contrast to the macrocyte associated with megaloblastic anemia and the pseudomacrocyte caused by viscoelastic defects, the volumetric macrocyte is characterized by an increased mean corpuscular volume and a normal cell diameter. The volumetric macrocyte proves to be thicker than the normocytic red blood cell. This large erythrocyte is overhydrated and contains an increased quantity of hemoglobin. The cell has many characteristics in common with the red blood cells of neonates. Volumetric macrocytosis accompanies sustained hydroxyurea therapy and may represent a drug-induced dyserythropoiesis.