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PubMed1984

Acute systemic changes in blood cells, proteins, coagulation, fibrinolysis, and platelet aggregation after frostbite injury in the rabbit.

Acute systemic blood changes were measured in New Zealand white rabbits after severe and mild frostbite injury to the foot. There were observed after 72 hr, in the severely frostbitten rabbits, a decrease in erythrocytes, hematocrit, lymphocytes, and albumin, and an increase in total leukocytes, neutrophils, platelets, fibrinogen, and antithrombin III. Mildly frostbitten rabbits showed similar changes except for no changes in the platelets, albumin, and antithrombin III. In severely frostbitten rabbits, after 72 hr, the changes in the plasma coagulation tests were a prolonged partial thromboplastin time, an accelerated prothrombin time, and increased activities of Factors VII, IX, X, and XI. In mildly frostbitten rabbits there were a prolonged partial thromboplastin time and an increased activity of Factor VII. No changes in fibrinolysis were seen in either group of rabbits. Platelet aggregation, studied only in the severely frostbitten rabbits, showed a change only by an increase in the slope of the collagen-induced platelet aggregation. The blood changes observed in the rabbit model are different than those reported in human frostbite cases. No disseminated intravascular coagulation was apparent in the rabbit model after frostbite injury.

Acute Disease↗

PubMedDate not supplied

Conductance method for the measurement of cross-sectional areas of the aorta.

A modified conductance method to determine the cross-sectional areas (CSAs) of arteries in piglets was evaluated in vivo. The method utilized a conductance catheter having four electrodes. Between the outer electrodes an alternating current was applied and between the inner electrodes the induced voltage difference was measured and converted into a conductance. CSA was determined from measured conductance minus parallel conductance, which is the conductance of the tissues surrounding the vessel times the length between the measuring electrodes of the conductance catheter divided by the conductivity of blood. The parallel conductance was determined by injecting hypertonic saline to change blood conductivity. The conductivity of blood was calculated from temperature and hematocrit and corrected for maximal deformation and changes in orientation of the erythrocytes under shear stress conditions. The equations to calculate the conductivity of blood were obtained from in vitro experiments. In vivo average aortic CSAs. determined with the conductance method CSA(G) in five piglets, were compared to those determined with the intravascular ultrasound method CSA(IVUS). The regression equation between both values was CSA(G)=-0.09+1.00 x CSA(IVUS), r=0.97, n=53. The mean difference between the values was -0.29%+/-5.57% (2 standard deviations). We conclude that the modified conductance method is a reliable technique to estimate the average cross-sectional areas of the aorta in piglets.

Animals↗

PubMed2006

Capillo-venous flow in the brain: significance of intravascular RBC aggregation for venous flow regulation.

Despite numerous reports on the regulation of cerebral arterial blood flow, little work has been done on that of the capillary and venous system. We have examined capillo-venous blood flow in the rat intraparenchymal cerebral cortex, employing a high-speed video confocal fluorescence microscope and our own software (KEIOIS-2) to track individual RBCs and to document velocity changes in single capillaries and veins. We found temporal and spatial heterogeneous changes in capillary RBC density (hematocrit), RBC recruitment, oscillation of capillary flow or vasomotion, and capillary density unrelated to arteriolar diametric changes. In veins, blood flow was also quite variable in time and space, and at a high frame rate venous blood per se was observed as a moving column of amorphous RBC aggregates with irregular edges; we believe this is the first report of such an observation under physiological conditions. The formation of such intravascular RBC aggregates would enforce slowing of blood flow and vice versa: RBC aggregation was in turn entirely flow-dependent. In rapid venous flow, RBCs appeared as a straight gathering of individually separated and dispersed cells. At capillo-venous junctions, an "RBC pouring" process appeared to occur, with RBCs either being sucked up from the capillary, merging, or being held back in the capillary. Changes in venous blood viscosity due to RBC aggregation are likely to be involved in this process. These findings suggest that the capillo-venous junction somehow participates in the regulation of appropriate tissue capillary flow in toto.

Animals↗

PubMed1989

Microvascular responses in copper-deficient rats.

In this study on copper deficiency, the rat crewmaster microcirculation was used as a model for endogenous histamine release and platelet thrombi formation. Male Sprague-Dawley rats were fed either a copper-supplemented diet (CuS, 5 ppm) or a copper-deficient diet (CuD, 0 ppm) for 5 wk before experimentation. The crewmasters of anesthetized rats were spread in a Krebs-filed tissue bath. In venules of CuS animals, photoactivation of intravascular fluorescein isothiocyanate tagged to bovine serum albumin caused significant platelet aggregation and reduction of red blood cell column diameter (RBCCD) by 40 min and stasis of flow by 60 min. In CuD animals there was only minor platelet aggregation and no reduction in RBCCD. Platelet aggregometry studies did not demonstrate reduced platelet aggregation in the CuD group, suggesting that copper deficiency alters the endothelium to inhibit adhesion. Compound 48/80 (1.0 and 10.0 microgram/ml) induced macromolecular leakage in both CuS and CuD groups, with the response in the CuD animals being significantly greater. The results demonstrate that copper deficiency results in alterations of the regulatory mechanisms governing inflammation and thrombosis.

Animals↗

PubMed1975

The pathogenesis of Vaccinia virus toxicity. II. An electron microscopic study.

The intravenous injection of mice with toxic doses of vaccinia virus, prepared in the Ehrlich ascites carcinoma, usually produces fatal intravascular coagulation, within 24 hours. Light and electron microscope studies demonstrate occlusion of the microcirculation of lungs and livers by fibrin. Fibrin deposition appears to be prevented in mice injected with heparinized virus preparations. However, in lieu of fibrin deposition, within the microcirculation widespread intravascular platelet aggregation occurs. Platelets within these aggregates are in various stages of degranulation, and some platelets have phagocytosed vaccinia virus. Platelet aggregation was not observed in mice receiving injections of heparinized material prepared from uninfected tumors. In mice surviving longer than 12 hours, hepatocytes and endothelial cells of pulmonary capillaries are the sites of viral replication. Although many hepatocytes are infected in mice surviving longer than 12 hours, it is postulated that hepatocyte necrosis is in part due to the congestive effects resulting from obstruction of liver and pulmonary capillaries. These studies suggest that vaccinia virus may trigger in vivo platelet aggregation, and that obstruction of the lung and liver microcirculation by these aggregates is the initial lesion of vaccinia virus toxicity.

Animals↗

PubMed1976

[Legal abortion and hemostasis. Histological examinations and comparison to post partum hemostasis (author's transl)].

30 women were examined to determine the hemostasis during the legally induced abortion. The blood coagulated in the intervillous spaces while the fetus is removed. Immediately after the termination of the curettment the nidation area is covered by filaments of fibrin and incorporated erythrocytes. More frequent as post partum platelet thrombi occur especially in the area of decidua parietalis. The intravascular findings are similar to post partum changes after the removal of the placenta. Obstruction clots of the spiral arterioles contain fibrin deposits, pletelet thrombi and erythrocytes (mixed form of thrombi). Residual decidua and trophoblast cells are seldom involved in the obturation of the vessels. The traumatic damages of the uterine wall are described (extravascular fibrin deposits, interstitial bleeding, succulent tissue a.s.o.).

Abortion, Legal↗

PubMed2004

The platelet function defect of paroxysmal nocturnal haemoglobinuria.

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare, acquired stem cell disorder, characterised by an abnormal susceptibility of red blood cells to complement induced lysis, resulting in repeated episodes of intravascular haemolysis and haemoglobinuria, thromboembolic events at atypical locations and, to a much lesser extent, bleeding complications. Platelet function is assumed to be abnormal, however, a defect has not yet been characterised and underlying mechanisms remain elusive. To explore these issues, we investigated platelet function in PNH patients using assays for clot formation under low and high shear force (thrombelastography and PFA100 device), adhesion to glass beads in native whole blood (Hellem method), aggregometry using various agonists (Born method), and flow cytometric assays for baseline and agonist-induced surface expression density of alpha-granule (CD62P) and lysosomal granule proteins (CD63), ligand binding to surface receptors (thrombospondin), and expression density of activation-induced neoepitopes of the fibrinogen receptor complex (PAC-1). Platelet PNH clone size determined by CD55 and CD59 labelling was compared to the clone sizes of granulocytes, monocytes, erythrocytes, and reticulocytes. A profound reduction of platelet reactivity was observed in PNH patients for all "global function" assays (clot formation, adhesion, aggregation). Platelet hyporeactivity was confirmed using flow cytometric assays. Whereas baseline levels of flow cytometrically determined platelet activation markers did not differ significantly between controls and PNH patients, agonist-induced values of all markers were distinctly reduced in the PNH group. Moreover, significantly reduced white blood cell counts (3.1/nl vs. 5.9/nl), haemoglobin values (9.5 vs. 14.3/g per dl), and platelet counts (136 vs. 219/nl) delineate profound tricytopenia in PNH patients. The fraction of particular cell types lacking the surface expression of GPI-anchored glycoproteins is referred to as the respective PNH clone; median PNH clone sizes of cells with short life spans (reticulocytes, platelets, granulocytes) was 50-80% of total cell populations compared to 20% of red blood cells. The results of our laboratory investigations show, that in PNH, reduced platelet counts coincide with reduced platelet reactivity. The foremost clinical complication in PNH, however, is venous thromboembolism, very probably induced by an activated and dysregulated plasmatic coagulation system. From these seemingly contradictory findings we infer, that part of the platelet hyporeactivity is probably due to reactive downregulation of platelet function in response to chronic hyperstimulation. The overall result is thought to be an unsteady balance, associated with thromboembolism in a larger proportion of patients, and with bleeding in a smaller proportion.

Adolescent↗

PubMed1975

[Giant occipital hemangioendothelioma with thrombocytopenia, anemia and hypofibrinogenemia treated by total excision (author's transl)].

An infant with a large occipital hemangioendothelioma with thrombocytopenia, anemia, and hypofibrinogenemia--Kasabach-Merritt syndrome--was reported. The case, a male neonate is unique, for this is the first report with this syndrome in whom the large hemangioma was noted at birth on the midocciput simulating the occipital encephalomeningocele. With the development of thrombocytopenia of 84,000 per mm3, hypofibrinogenemia of 92 mg/dl, anemia (erythrocyte 193 X 10(4) per mm3, hemoglobin 5.9 g/dl, hematocrit 16 vol%), hepato-splenomegalia, enlargement and bluish discoloration of the tumor noted on the 21/2 months of life, total excision was intended prior to the expected occurence of the systemic purpura. The patient received fresh whole blood transfusion immediately prior to surgery, and the total excision was successfully performed. Excessive bleeding was not encountered. Abrupt rise in the platelet count, red blood cell count, hemoglobin and hematocrit to normal range was noted at the first postoperative day; he was discharged on the 17th day after surgery. Nineteen months' follow-up showed normal hematologic findings with good somatic and mental development. The specimen weighing 250 g. revealed benigh hemangioendothelioma. Silver impregnation demonstrated lobular aggregates of small vascular channels. Papillary projection of interstitial cells into the lumen, reaction of the endothelium of the vessels, newly formed thrombus, ishemic necrosis and hemorrhage, hyaline degeneration of interstitial tissue were noted. These findings suggested the disseminated intravascular coagulation within the tumor followed by fibrinolysis accounts for loss of blood corpuscles, platelet, fibrinogen and clotting factors, which leads ultimately to the consumption coagulopathy and diffuse bleeding.

Afibrinogenemia↗

PubMed2002

Intravascular plug formation induced by poly-APS is the principal mechanism of the toxin's lethality in rats/rat tissues.

Toxic water soluble polymeric 3-alkylpyridinium salts isolated from the sponge Raniera sarai strongly inhibited AChE in vitro. In vivo, experimental animals died due to plugs formed in microcirculation. The mechanism of this plug formation is unknown. In vitro, the toxin did not affect the coagulation rate, but the rate of platelet aggregation was accelerated in a dose-dependent manner. The hemolytic activity of poly-APS was diminished by the addition of serum proteins in a dose-dependent manner. These results support the conclusion that non-specific binding to proteins is the underlying mechanism of the lethality of poly APS.

Animals↗

PubMedDate not supplied

Haemostatic changes in children with cyanotic and acyanotic congenital heart disease.

This study was undertaken to screen children with congenital heart disease for coagulation abnormalities and to compare the groups of cyanotic and acyanotic children with congenital heart disease with respect to abnormalities of the coagulation system. Following investigations were done in all the patients: complete blood count, erythrocyte sedimentation rate, peripheral smear examination, bleeding time, prothrombin time, activated partial thromboplastin time, assay of fibrinogen, D-dimer, factors VII and VIII and antithrombin III. Red cell indices were determined in 12 control, 12 acyanotic and 20 cyanotic children. Twenty-five patients each, with echocardiographically proven cyanotic and acyanotic congenital heart disease under 12 years of age constituted the study group; as many children of the same age group were included as the control group. The results showed isolated abnormalities of laboratory tests with equal frequency (28%) in acyanotic and cyanotic groups but coexisting abnormalities of more than one test were seen in significantly larger number of cyanotic children (5/25 and 16/25, respectively). A significant association was noted between thrombocytopenia and a high haematocrit in cyanotic patients. It is concluded that laboratory abnormalities of tests of haemostasis are more common in cyanotic congenital heart disease patients. The patterns of laboratory abnormalities suggest a chronic compensated disseminated intravascular coagulation at a subclinical level, reduced synthesis of clotting factors and/or deranged platelet aggregation in different subgroups of patients.

Blood Coagulation Factors↗

PubMed1975

The pathogenesis of Vaccinia virus toxicity. I. The role of virus-platelet interaction.

When mice are injected intravenously with a large dose of vaccinia virus, prepared in the Ehrlich ascites carcinoma of the mouse, there is a precipitous loss of plasma fibrinogen and blood platelets. Death occurs usually within 24 hours. A specific role of the virus in this toxic syndrome can be demonstrated when heparin is employed to circumvent intravascular coagulation and fibrinogen loss. Heparin does not prevent a profound thrombocytopenia from occurring, but it modifies the rate of platelet loss. Toxicity is prevented when heparinized virus preparations are pretreated with beta-propiolactone or specific antibody, although a mild thrombocytopenia occurs. Thrombocytopenia does not occur in mice injected with heparinized material prepared from uninfected tumors. These studies indicate that the basic mechanism of vaccinia virus toxicity is an early interaction between infectious virus and blood platelets, with marked thrombocytopenia and consequential pathophysiologic changes.

Afibrinogenemia↗

PubMed1998

Thrombotic thrombocytopenic purpura plasma enhances platelet-leucocyte interaction in vitro.

In thrombotic thrombocytopenic purpura (TTP), intravascular platelet aggregation and formation of platelet-rich thrombi impair the microcirculation. TTP plasma has been shown to induce aggregation of normal platelets in vitro. The present study investigates the formation of activated platelet aggregates (aPAg) induced by TTP plasma, with particular attention to their binding to leucocytes (LPAg). Results were compared with the effects of plasmas from normal controls (CTL) and from patients with immune thrombocytopenic purpura (ITP) or thrombosis (THR). Following addition of test plasma to normal whole blood (WB), aPAg and LPAg were assayed by flow cytometry using mAbs against CD41 (platelet marker), CD62p (platelet activation marker) and CD45 (pan-leucocyte marker), Compared to control plasma, TTP plasma was more potent than ITP or THR plasma in increasing aPAg: only TTP plasma significantly promoted leucocyte binding to give increased LPAg. Prior removal of neutrophils (PMN) from WB by beads coated with anti-CD15 mAb largely prevented formation of aPAg and LPAg. However, TTP plasma added to normal platelet-rich plasma significantly increased aPAg, which suggested possible hindrance of aPAg formation by erythrocytes and other leucocytes in PMN-depleted blood. We concluded that TTP plasma was most potent in the induction of aPAg and unique in promoting LPAg formation in WB. Neutrophils, and not other leucocytes, appear to be essential for LPAg formation. Enhanced PMN-platelet interaction in the microcirculation may facilitate platelet adhesion to vessel walls and promote the formation of platelet-rich microthrombi in TTP.

Adult↗

PubMed2006

[Platelet activation and inflammation markers in patients with coronary heart disease and depression].

AIM: To study morphological features and functional activity of platelets, their relations with the level of inflammation markers in coronary heart disease (CHD) patients with depression. MATERIAL AND METHODS: The study group consisted of 33 CHD patients with stable effort angina (NY-HA FC I-III), 14 had depression, 19 were free of depression. Sixteen healthy volunteers comprised the control group. Platelet aggregation was registered by a mean size of aggregates and turbidometrically. Platelets shape, leukocytic-thrombocytic and erythrocytic-thrombocytic aggregates (LTA, ETA) in the whole blood were studied electron-microscopically. The levels of IL-2, IL-6, TNF-alpha, sVCAM, hsCRP were measured in the blood, serotonin--in platelets. RESULTS: Spontaneous aggregation enhanced in 52.6% CHD patients (p < 0.05). The blood contained reticular platelets, high number of prothrombocytes (p < 0.05), mean volume of thrombocytes was greater (p < 0.05). This reflected changes in megakaryocytopoiesis. Some of the patients had LTA and ETA. Out of inflammation markers, only IL-6 and sVCAM were elevated (p < 0.01), hsCRP concentration rose, but not above normal range. Serotonin in platelets was the same in the patients and controls. Depression aggravated the disorders and elevated other indices. Spontaneous aggregation was high in 71.4% of depressive CHD patients. The count of reticular platelets, prothrombocytes, mean volume platelets were also elevated. LTA and ETA were high in all the depressive patients. Elevated were also concentrations of IL-6, sVCAM, IL-2, hsCRP. Serotonin in platelets was low (p < 0.05). CONCLUSION: Depression stimulates functional activity of platelets, is a factor of risk of intravascular inflammation and contributes to development of thrombotic complications in CHD patients.

Aged↗

PubMed1996

[Changes in red blood cell aggregation rate after aneurysmal subarachnoid hemorrhage].

Red blood cell (RBC) aggregability is one of the important factors determining blood viscosity in the microcirculation. The RBC aggregation rate was monitored in 38 patients who underwent early aneurysmal clipping surgery after subarachnoid hemorrhage (SAH). The intravascular factors (hematocrit, serum albumin, alpha 2-macroglobulin, fibrinogen, IgG) that influence RBC aggregation were also examined. The RBC aggregation rate increased on days 5-7 but decreased significantly as a result of hypervolemic hemodilution therapy (H-H therapy). The hematocrit level was also reduced by H-H therapy. The serum albumin concentration decreased and the serum alpha 2-macroglobulin concentration increased significantly on days 5-7. After H-H therapy, the serum albumin concentration increased and the serum alpha 2-macroglobulin concentration decreased significantly. Serum IgG and plasma fibrinogen concentrations did not change significantly. It is known that albumin decreases and alpha 2-macroglobulin increases RBC aggregability. It has become apparent that serum albumin and alpha 2-macroglobulin play important roles in the determination of RBC aggregability after SAH. We conclude that the improvement in RBC aggregability induced by H-H therapy is effective for reversing progressive neurological deterioration due to cerebral vasospasm.

Adult↗

PubMed1991

[Status of the hemostatic system in patients with chronic lung diseases].

Blood rheologic properties and homeostasis system were comprehensively examined in 23 patients with fibrous-cavernous pulmonary tuberculosis and 58 patients with various chronic nonspecific pulmonary diseases complicated by respiratory failure. The patients were found to have signs of erythrocyte edema, their more rapid depletion, lower resistance and higher aggregation which was accompanied by increased hematocrit and normal erythrocyte count. The thromboelastograms showed that all all phases of blood coagulation were shortened and fibrinolysis was deeply depressed. There was an increase in activated partial thromboplastin and thrombin time, a reduction in the values of the prothrombin indices and antithrombin III activity and higher heparin levels. The fibrinogen level was either normal or reduced despite an increase in other acute phase reactants, followed by the appearance of large amounts of blocked fibrinogen in the blood. Analysis of the findings enabled one to regard a combination of the above changes as signs of the latent DIC syndrome. Determination of fibrin and fibrinogen degradation products in a deep and long-term inhibition of fibrinolysis loses its diagnostic significance.

Alveolitis, Extrinsic Allergic↗

PubMedDate not supplied

Cytology of well-differentiated and poorly differentiated hemangiosarcoma in fine needle aspirates.

The cytologic descriptions of fine needle aspirates from one well-differentiated and one poorly differentiated hemangiosarcoma are reported and correlated with the histologic findings. Aggregates of two to ten cells predominated in the aspirate from the well-differentiated tumor. In Papanicolaou-stained smears and filter preparations, single nuclei, resembling intravascular nuclear protrusions in a punch biopsy specimen, projected from some of these cell groups. Shallow longitudinal invaginations characterized the hyperchromatic nuclei. Erythrophagocytosis and cytoplasmic vacuoles were evident in Wright's-stained smears. Individual binucleate cells predominated in aspirates from the poorly differentiated tumor. Their nuclei exhibited thicker membranes, more prominent nucleoli and clearer parachromatin than did those of cells from the well-differentiated tumor. Cytoplasmic projections were common and sometimes quite complex. While these cytologic features are not pathognomonic, they are indicative of a malignant neoplasm and can be combined with clinical and other histopathologic data to provide a complete diagnosis.

Adult↗

PubMed1988

An in vivo chicken model for peripheral intravascular human fibrin clot detection.

A chicken model was prepared that provides a simple and economical method of evaluating the use of fibrin-specific monoclonal antibody 64C5 in the detection of peripheral vascular thrombi. Human fibrin was clotted in segments of a chicken's femoral artery and vein prior to intravenous injection of radioiodinated antibody 64C5. After a 3-hr perfusion time, the thrombosed and contralateral control segments of the vessels were excised and counted for radioactivity. The radiolabeled 64C5 uptake ratio of the thrombosed segment to the control segment was 5.4 +/- 1.2 (p less than 0.007) in the femoral artery, and 3.8 +/- 1.1 (p less than 0.02) in the femoral vein. This in vivo chicken model may also find application in studies of targeting agents for human fibrin.

Animals↗

PubMed1986

Pulmonary hemodynamic effects of antisheep serum-induced leukopenia.

Antisheep antileukocyte serum (ALS) was produced in rabbits, purified, and adsorbed against erythrocytes and platelets. The ALS was infused intra-arterially over a 3-hour period into anesthetized sheep (n = 6) prepared with lung lymph fistulas. Pulmonary vascular resistance (PVR) and pulmonary lymph flow (Qlym) increased two- to threefold while the lymph-to-plasma protein concentration ratio (L/P) did not change from baseline, suggesting an increase in pulmonary vascular permeability to proteins. The arterial leukocyte count decreased from 4,935 +/- 840 to 1,385 +/- 325 cells/microliters, the neutrophil count decreased from 1,045 +/- 265 to 340 +/- 130 cells/microliters, and the platelet count decreased from 2.8 X 10(5) +/- 0.2 X 10(5) to 0.65 X 10(5) +/- 0.12 X 10(5) cells/microliters. ALS induced neutrophil aggregation in vitro, but not platelet aggregation. In the present study, we also examined the effects of ALS-induced leukopenia on the increase in pulmonary vascular permeability after intravenous alpha-thrombin challenge to assess the role of leukocytes in mediating the increased permeability response. Sheep (n = 5) were made leukopenic by an intramuscular injection of ALS; Qlym was in the normal range 4 to 5 hours after the ALS administration. In the leukopenic group, thrombin challenge caused an increase in Qlym from 7.8 +/- 0.7 to 12.9 +/- 1.9 ml/hr (a 64% increase) while L/P decreased from 0.86 +/- 0.04 to 0.70 +/- 0.05 (a 19% decrease). In contrast, thrombin-induced intravascular coagulation in control sheep (n = 5) produced a 250% increase in Qlym with an increase in L/P. The results indicate that leukocytes are required for the increase in lung vascular permeability after thrombin-induced intravascular coagulation.

Animals↗