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PubMed2002

Rapid recovery of platelet count following administration of liposome-encapsulated clodronate in a mouse model of immune thrombocytopenia.

Immune thrombocytopenic purpura (ITP) is a haematological disorder characterized by increased platelet consumption. The destruction of platelets is mediated by the reticulo-endothelial system (RES), particularly by splenic and hepatic macrophages. Previously, we demonstrated in a mouse model of thrombocytopenia that the depletion of these cells by liposome-encapsulated clodronate (LIP-CLOD) induces the recovery of the platelet count. We now report that LIP-CLOD is capable of reversing the thrombocytopenia with minimal effects on both, functional RES integrity and platelet functionality. Our data indicate that thrombocytopenic mice treated with low doses of LIP-CLOD/body weight increase the platelet count to haemostatically safe values within 18 h of treatment. The predictable bleeding time was significantly decreased in these mice, suggesting that the circulating platelets have enhanced haemostatic capacity. Platelet functionality measured through the ADP-induced fibrinogen-binding assay showed normal platelet activation after treatment. Regarding immunological competence, mice treated with LIP-CLOD showed similar antibody titres against sheep red blood cells. However, antibody-dependent cell-mediated cytotoxicity carried out by splenocytes was reduced. All these data demonstrate that LIP-CLOD deserves consideration as a potential therapeutic approach in thrombocytopenic states in which the rapid increase of platelet count is the primary goal.

Animals↗

PubMed2000

Increased leukocyte-platelet adhesion in chronic myeloproliferative disorders with high platelet counts.

The heterophilic adhesions between monocytes and platelets may result in the modification of both platelet and monocyte function. This mutual modification includes a greater activation of platelets with increased production of PDGF and other metabolites as well as an enhanced tissue factor expression of monocytes with greater activity in the circulation. The heterophilic aggregation has been well documented during extracorporal circulation, haemodialysis and in diabetic retinopathy. Here we provide evidence that there is significant increase of monocyte-platelet aggregates in disorders associated with high platelet counts, such as chronic myeloproliferative disorders. The presence of these heterophilic aggregates may contribute to the vascular complications observed frequently in polycythaemia vera and essential thrombocythaemia.

Adult↗

PubMed1980

Platelet count in temporary residents of high altitude.

Platelet count was estimated in 65 lowlanders temporarily staying at altitudes above 3,000 m. They were divided in subgroups according to the length of their continuous stay. For comparison, 51 highlanders who were born and reared at high altitude and 48 lowlanders who had never been to an altitude of more than 1,000 m were also studied. Gradually rising counts becoming highly significant (P < 0.001) as compared to the lowlanders after 31 days of stay and stabilizing close to the values in highlanders after 181 days were noted. The significance of these findings in the light of existing knowledge is discussed.

Adult↗

PubMed2005

The effect of oestrogen on megakaryocyte differentiation and platelet counts in vivo.

BACKGROUND: Oestrogen alters megakaryocyte number in humans and mice. In mice, high-dose oestrogen stimulates an initial increase in megakaryocyte number followed by a decrease. However, the cellular action, effect of physiologically circulating and smaller supra-physiological oestrogen doses and whether changes in megakaryocyte number alter platelet counts have not been studied. METHODS: To further examine oestrogen's effect on megakaryocytes and platelets we administered intact or ovariectomised mice various doses of oestrogen and measured megakaryocyte and platelet counts. To determine the cellular mechanism by which oestrogen influences megakaryocytopoesis we also examined its effect on markers of megakaryocytic differentiation (CD41, CD61, CD34). RESULTS: We found that large doses of oestrogen (500 microg/kg) increased mature CD41+ megakaryocyte number within 2 days, and this was associated with an increase in circulating platelets. Smaller supra-physiological doses (100 microg/kg) lacked this anabolic effect, but still suppressed megakaryocyte and platelet number by day 10 in intact and ovariectomised mice. This was preceded by a reduction in the number of CD61+ megakaryoblasts and CD34+ precursors available to form mature megakaryocytes. In contrast, ovariectomy had no effect on megakaryocyte or platelet number, indicating that circulating oestrogen concentrations do not influence megakaryocyte differentiation or activity. CONCLUSIONS: Our data suggest that in mice at least platelet counts reflect changes in megakaryocyte number, and while both are independent of physiological hormone concentrations, they are sensitive to even small supra-physiological doses of oestrogen. Therefore, to ovoid disrupting platelet homeostasis the dose of oestrogen given should be no more than replacement.

Animals↗

PubMed2004

[Clinical efficacy of AST/ALT ratio and platelet counts as predictors of degree of fibrosis in HBV infected patients without clinically evident liver cirrhosis].

BACKGROUND/AIMS: Hepatic fibrosis is an important prognostic factor in chronic hepatitis B. Liver biopsy is a gold standard diagnostic tool but an invasive procedure, so it cannot be done on all patients. We evaluated the clinical efficacy of AST/ALT ratio and platelet counts as predictors of fibrosis in chronic hepatitis B. METHODS: We reviewed retrospectively clinical records of 323 patients, who visited Kyungpook National University Hospital for chronic hepatitis B and underwent liver biopsy from September 1998 to May 2002. Correlation with laboratory parameters with hepatic fibrosis stage was identified. RESULTS: Of 323 patients, there were 278 male patients with mean age 27 (9~59). Platelet counts showed a significant correlation (r=-0.343, p=0.000), and AST/ALT ratio showed a weak but significant correlation (r=0.137, p=0.013) with fibrosis stage. Patients with severe fibrosis or cirrhosis (stage 3 and 4) can be identified to have AST/ALT ratio > 1 and platelet counts < 150,000/mm3, which showed with positive predictive value of 66.7%. Sensitivity, specificity, and negative predictive value were 14.6%, 97.5%, and 77.0%, respectively. CONCLUSIONS: In chronic hepatitis B patients without clinical evidence of cirrhosis, severe hepatic fibrosis might be predicted using laboratory parameters of AST/ALT > 1 in combination with platelet counts. However, its sensitivity is too low to replace liver biopsy.

Adolescent↗

PubMed2000

[Thrombocytosis versus thrombocythemia--differential diagnosis of elevated platelet count].

Differentiation of an elevated, repeatedly determined platelet count (> or =500x10(9)/l) includes the discrimination between reactive causes generated by a variety of underlying conditions and a neoplastic myeloproliferative disorder (CMPD). In addition to clinical findings, the evolution of laboratory data during follow-up and histology of the bone marrow exerts a significant diagnostic impact. Characteristic features are not only expressed by hematopoiesis, but also by the myeloid stromal compartment. While the megakaryocyte-rich subtype of chronic myeloid leukemia (CML) and the 5q(-) syndrome (MDS) are dominated by abnormal micromegakaryocytes, in polycythemia vera (PV) this cell lineage reveals a pleomorphous appearance. In essential thrombocythemia (ET), a prevalence of giant megakaryocytes with deeply lobulated (staghorn-like) nuclei may be encountered. A clear-cut discrimination of ET from early (hypercellular) stages of idiopathic (primary) myelofibrosis (IMF) presenting with thrombocythemia becomes possible, provided the conspicuous atypical features of megakaryopoiesis characterizing the latter entity are taken into account. Moreover, CML displays a predominance of the granulocytic lineage whereas PV shows a panmyelosis or trilineage proliferation, involving erythropoiesis, in particular. In contrast, erythropoiesis is markedly reduced in CML and to a lesser degree also in IMF. In CMPDs extreme values of iron deposits may be found, ranging from a total lack (PV) to minor amounts (CML) and a normal staining reaction (ET). Similar results are exhibited regarding reticulin fibrosis, which is usually not present in ET, rarely observed in PV and detectable to a variable degree in CML and IMF.

Diagnosis, Differential↗

PubMed1978

Electronic platelet counting with capillary blood samples--experiences in a paediatric clinic.

For several reasons, electronic platelet counts have not been generally adopted in paediatric routine laboratories. A method of platelet counting in capillary blood samples using an electronic counter is described. This is based on brief centrifugation of the blood sample after the addition of a diluent containing heparin/dextran and with a density of 1.050. The thrombocytes are uniformly suspended in the supernatant after 5 min of centrifugation at 250 g, so that the counting procedure in the electric unit can follow immediately. This simplified, dependable and reproducible method is also suitable for venous blood, and as a result of several years of successful trial, it can be recommended for routine use, especially in clinics with paediatric patients.

Blood↗

PubMed2005

Prenatal corticosteroid therapy for elevated liver enzyme/low platelet count syndrome: a case report.

BACKGROUND: Early preterm onset of elevated liver enzymes/low platelet count (ELLP) syndrome poses a significant management problem. CASE: Antepartum methylprednisolone, 40 mg/d intravenously was employed to stabilize ELLP syndrome, to achieve fetal lung maturity and to postpone delivery at 25 weeks and 5 days' gestation. Normalization of the liver transaminases and platelet count occurred with the use of corticosteroids, but sudden fetal death occurred at 28 weeks and 2 days' gestation. CONCLUSION: Prenatal corticosteroids may improve the biochemical and hematologic parameters of ELLP syndrome but may result in intrauterine death.

Adult↗

PubMed1991

[Prenatal evaluation of the platelet counts in the fetuses and the neonates of the mothers complicated with idiopathic thrombocytopenic purpura].

We investigated 25 pregnancies with ITP. The results were as follows. 1. The platelet counts of the maternal blood just before delivery were not correlated with those of the cord blood. 2. It was suggested that the maternal PAIgG value just before delivery could foretell the onset of neonatal thrombocytopenic purpura. 3. The platelet counts in fetal scalp blood were correlated with those of the cord blood, but falsely lower platelet counts were found in the fetal scalp samples. 4. We saw 5 cases of percutaneous umbilical blood sampling (PUBS) in pregnancies with ITP. PUBS was found to be a useful and safe method. The indications for PUBS and fetal platelet transfusion in pregnancy with ITP are discussed.

Cesarean Section↗

PubMed1998

Haematocrit, leukocyte and platelet counts and the severity of the ovarian hyperstimulation syndrome.

Previous studies have shown that severe ovarian hyperstimulation syndrome (OHSS) is secondary to circulatory dysfunction due to the simultaneous occurrence of increased vascular permeability and marked arteriolar vasodilation which lead to an intense homeostatic stimulation of the renin-aldosterone and sympathetic nervous systems and antidiuretic hormone (ADH). In the present report, we have investigated the correlation between changes in haematocrit concentration, and white blood cell (WBC) and platelet counts and the severity of OHSS, as assessed by these markers of effective intra-arterial blood volume, in a series of 50 patients. In comparison with recovery values (4-5 weeks after hospital discharge), OHSS patients showed arterial hypotension, tachycardia, oliguria, very high plasma concentrations of renin, aldosterone, norepinephrine and ADH, and increased mean haematocrit values and WBC and platelet counts. The haematocrit concentration values were directly related to the plasma concentrations of vasoactive substances (plasma renin activity, aldosterone, norepinephrine and ADH) during OHSS (P < 0.001). In contrast, no correlation was evident between WBC or platelet counts and neurohormonal measurements during the syndrome. It is concluded that haematocrit, but not WBC or platelet counts, can act as a biological marker of the severity of OHSS as indicated by plasma measurement of volume-dependent endogenous vasoactive substances.

Adult↗

PubMed2006

Influence of the needle bore size on platelet count and routine coagulation testing.

The phlebotomy technique, particularly the use of small-bore needles, may influence the reliability of coagulation testing and platelet count. Routine coagulation tests were assayed in blood specimens collected from 22 consecutive patients in three separate, sequential phlebotomies, using butterfly devices with different needle sizes. Test results of samples collected with 23 and 25 G needles were compared with those obtained with the currently recommended 21 G needle. Although both the prothrombin time and activated partial thromboplastin time displayed a trend towards lower values employing the smaller 23 and 25 G needles, results did not differ significantly from the reference 21 G needle specimen, with the exceptions of D-dimer (25 G versus 21 G needle, 186 +/- 70 versus 178 +/- 66/ml, P < 0.01) and platelet count (23 G versus 21 G needle, 246 +/- 55 versus 254 +/- 56 x 10(-3)/l, P < 0.01; 25 G versus 21 G needle, 240 +/- 55 versus 254 +/- 56 x 10(-3)/l, P < 0.01). None of the mean biases recorded for the parameters was clinically meaningful, nor did they exceed the current desirable analytical quality specifications for desirable bias. Results of the present investigation suggest that, when a proper technique is used and within certain limitations, butterfly devices with small-bore needles may be a reliable alternative to draw venous blood for platelet count and coagulation testing.

Adult↗

PubMed2005

Low preoperative platelet counts predict a high mortality after partial hepatectomy in patients with hepatocellular carcinoma.

AIM: To assess the validity of our selection criteria for hepatectomy procedures based on indocyanine green disappearance rate (K(ICG)), and to unveil the factors affecting posthepatectomy mortality in patients with hepatocellular carcinoma (HCC). METHODS: A retrospective analysis of 198 consecutive patients with HCC who underwent partial hepatectomies in the past 14 years was conducted. The selection criteria for hepatectomy procedures during the study period were K(ICG)>or=0.12 for hemihepatectomy, K(ICG)>or=0.10 for bisegmentectomy, K(ICG)>or=0.08 for monosegmentectomy, and K(ICG)>or=0.06 for nonanatomic hepatectomy. The hepatectomies were categorized into three types: major hepatectomy (hemihepatectomy or a more extensive procedure), bisegmentectomy, and limited hepatectomy. Univariate (Fisher's exact test) and multivariate (the logistic regression model) analyses were used. RESULTS: Postoperative mortality was 5% after major hepatectomy, 3% after bisegmentectomy, and 3% after limited hepatectomy. The three percentages were comparable (P = 0.876). The platelet count of 7.3X10(4)/microL died of postoperative morbidity, whereas 25% (6/24 patients) of patients with a platelet count of <or=7.3X10(4)/microL died (P<0.001). CONCLUSION: The selection criteria for hepatectomy procedures based on K(ICG) are generally considered valid, because of the acceptable morbidity and mortality with these criteria. The preoperative platelet count independently affects morbidity and mortality after hepatectomy, suggesting that a combination of K(ICG) and platelet count would further reduce postoperative mortality.

Blood Loss, Surgical↗

PubMed2005

Blood fluidity and outcome after femoropopliteal percutaneous transluminal angioplasty (PTA): role of plasma viscosity and low platelet count in predicting restenosis.

Rheological abnormalities are well known in patients with peripheral arterial occlusive disease (PAOD). We wanted to determine whether rheological variables are related to restenosis after femoropopliteal percutaneous transluminal angioplasty (PTA). In 114 patients (62 men; median age 70 years) undergoing femoropopliteal PTA for symptomatic peripheral arterial occlusive disease (PAOD) plasma viscosity, red cell aggregation, whole blood viscosity, hematocrit, fibrinogen, platelet count, leukocytes and C-reactive protein were determined the day after the procedure and at 1, 3, and 12 months. The primary endpoint was restenosis >50% documented by duplexsonography up to 12 months. Cox proportional hazards analysis was used to assess the risk of restenosis for postinterventional values of rheological variables. Forty-eight patients (42%) developed restenosis at 12 months. Patients with restenosis had higher baseline plasma viscosity (PV) (medians, 1.71 vs. 1.65 millipascal seconds [mPa.s]; p = 0.04) and lower platelet count (224 vs. 240 x 10(3)/microl; p = 0.03) than patients without restenosis. The hazard ratio (HR; 95% CI) of incident restenosis was 9.2 (1.12-76; p = 0.03) for PV and 0.99 (0.99-1.0; p = 0.07) for PLT. When examining jointly both high PV and low platelet count (PLT), patients with PV > 1.66 mPa.s and PLT < 233 x 10(3)/microl (i.e. variables split at their respective median) had an increased risk of restenosis (log-rank test p = 0.01). Multivariate Cox proportional hazard analysis showed that plasma viscosity (p = 0.02), low platelet count (p = 0.01), lesion length (p = 0.0037) and lack of hypertension (p = 0.01) were associated with restenosis at 12 months. No associations were found between restenosis and the other rheological and inflammatory variables studied. Our data suggest that increased PV and low PLT contribute to restenosis after femoropopliteal PTA.

Aged↗

PubMed1999

The effect of recombinant human erythropoietin on platelet counts is strongly modulated by the adequacy of iron supply.

The effect of recombinant human erythropoietin (rHuEpo) on megakaryopoiesis remains controversial. Treatment with rHuEpo in renal failure patients has been associated with a slight elevation of platelet counts. In animal studies, high doses of rHuEpo produced an increase of platelet counts followed by a gradual return to normal after 7 to 15 days or even a substantial degree of thrombocytopenia. However, because iron deficiency is also known to be associated with thrombocytosis, (functional) iron deficiency during rHuEpo could be contributing to these observations. We investigated the impact of iron supply on changes in platelet counts induced by rHuEpo. Rats were either fed normal food (normal rats) or received 1% carbonyl iron for 2 weeks or 3 months, as well as during the experiment, to achieve iron supplementation or overload, respectively. Rats of all three categories then received daily intravenous injections of rHuEpo (10, 50, or 150 U) or normal saline (0 U) for 20 days. With 0 to 10 U rHuEpo, platelets remained stable. In normal rats receiving 50 to 150 U rHuEpo, platelets increased to 120% to 140% of baseline at 4 to 12 days to level off at 120% at 16 to 20 days. This response was less sustained in splenectomized animals. Iron-supplemented rats receiving 50 to 150 U rHuEpo also increased platelets initially, but the peak was at day 4, followed by a gradual return to baseline and even a moderate thrombocytopenia later on. Iron-overloaded rats receiving 50 to 150 U rHuEpo also had increased platelets at day 4, but the duration of platelet increase was shorter, and they experienced a more pronounced degree of thrombocytopenia in proportion to the dose of rHuEpo. Because the early elevation of platelets was of larger magnitude than hematocrit changes, it is unlikely that it could be accounted for by shrinkage of plasma volume. Because it was observed in all three iron conditions, there appears to be some direct positive effect of rHuEpo on platelet production. However, after this transient effect, expanded erythropoiesis appears to exert a negative impact upon platelet production. Secondary thrombocytopenia was not related to splenic pooling, and its very slow correction after cessation of rHuEpo therapy is not compatible with changes in platelet survival. Rather, it is consistent with stem cell competition between erythroid and megakaryocytic development. However, this secondary thrombocytopenia is masked by (functional) iron deficiency in rats not receiving an adequate iron supply from food or stores.

Animals↗

PubMed1992

Essential thrombocythemia in pregnancy: platelet count and pregnancy outcome.

We report our experience of 4 successful pregnancies (including a pair of twins) in 3 women who have essential thrombocythemia (ET). All of the patients had a significant fall in platelet count (> 20% of non-pregnant state) during the course of the pregnancy. A review of the literature and our own experience suggests that the degree of platelet count reduction may be correlated with pregnancy outcome. Close monitoring of the platelet count is useful in the management of these cases.

Adult↗

PubMed1999

Spurious elevation of automated platelet counts in secondary acute monocytic leukemia associated with tumor lysis syndrome.

The intent of this article is to describe the effect of tumor lysis on automated platelet counts in therapy-related, secondary acute monocytic leukemia. The first patient was a 69-year-old man with large cell carcinoma of the lung who developed acute monocytic leukemia 1(1/2) years after initiation of radiation and chemotherapy for his carcinoma. The second patient was a 72-year-old female with peripheral T-cell lymphoma who developed acute monocytic leukemia 1 year after initiation of chemotherapy for her lymphoma. Platelet counts were determined by the automated Coulter (STKS) counter. Both patients had clinical and laboratory evidences of tumor lysis syndrome and disseminated intravascular coagulation. The peripheral blood smears revealed numerous fragments of leukemic cells and apoptotic cells with pyknotic nuclei. The Coulter machine enumerated these cellular fragments as platelets, resulting in falsely elevated platelet counts. Awareness of this laboratory artifact in secondary acute monocytic leukemia with tumor lysis syndrome is important so that potential life-threatening thrombocytopenia is not overlooked.

Aged↗

PubMedDate not supplied

Effect of serum from thrombocytopenic patients on platelet count in blood of mice.

Estimation of the effect of sera obtained from patients suffering from several forms of megakaryocytic (immune) thrombocytopenia (19), and those with acute non-lymphoblastic leukemia (13), on the platelet count in the peripheral blood of mice was carried out. Several groups of mice were injected intravenously with 0.2 ml of patients' sera, and the platelet count was followed up for 10 days. A marked and highly significant decrease of platelet count in recipient mice was established even 6 hours after the application of both groups of patients' sera. In the control group of mice receiving pooled serum of healthy persons this decrease was not registered. It can be presumed with great probability that the mechanism of development of thrombocytopenia in both groups of patients is very similar: there is an extremely increased destruction of platelets in the peripheral blood in cases with immune thrombocytopenia by antibodies, and in cases with acute leukemias by antibodies and/or other cytotoxic substances. In further investigations the influence of thrombopoietin on this phenomenon will be tested.

Animals↗

PubMed2006

Effects of argatroban therapy, demographic variables, and platelet count on thrombotic risks in heparin-induced thrombocytopenia.

STUDY OBJECTIVES: We investigated the effects of the direct thrombin inhibitor argatroban, patient demographics, and the platelet count on thrombotic risks in heparin-induced thrombocytopenia (HIT), a serious thrombotic condition, to determine if argatroban provides effective antithrombotic therapy in patients with HIT without increasing bleeding. DESIGN: We retrospectively analyzed thrombotic outcomes in 882 HIT patients (697 patients receiving mean argatroban doses of 1.7 to 2.0 mug/kg/min for 5 to 7 days, plus 185 historical control subjects) from previously reported prospective studies. Time-to-event analyses of our primary end point-a thrombotic composite of death due to thrombosis, amputation secondary to HIT-associated thrombosis, or new thrombosis within 37 days-and the individual components were conducted, with hazard ratios estimated for treatment with and without adjustments for patient age, gender, race, weight, and baseline platelet count. MEASUREMENTS AND RESULTS: Argatroban, vs control, significantly reduced the thrombotic composite risk (HIT: hazard ratio, 0.33; 95% confidence interval [CI], 0.20 to 0.54, p < 0.001; HIT with thrombosis: hazard ratio, 0.39; 95% CI, 0.25 to 0.62, p < 0.001), regardless of covariate adjustments. More argatroban-treated patients than control subjects remained thrombotic event free during follow-up, regardless of whether baseline thrombosis was absent (91% vs 73%) or present (72% vs 50%). Argatroban significantly reduced new thrombosis (p < 0.001) and death due to thrombosis (p </= 0.001). Major bleeding was similar between groups (6 to 7%, p = 0.74). Thrombotic risks were 2 times greater in nonwhite than in white patients, 1.7 times greater in female than male patients with HIT and thrombosis, and increased with decreasing weight or platelet count. CONCLUSIONS: Argatroban, vs control, provides effective antithrombotic therapy in patients with HIT, without increasing bleeding. Patients at higher risk for HIT-associated thrombosis include women, nonwhites, and individuals with current HIT-associated thrombosis, lower body weight, or more severe thrombocytopenia.

Aged↗