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PubMedDate not supplied

Vascular endothelial growth factor levels in serum and plasma following esophageal cancer resection--relationship to platelet count.

In patients with cancer circulating vascular endothelial growth factor (VEGF) may be tumor-derived and have prognostic significance. Activated platelets may also be a source of VEGF, releasing it in serum formation. Debate exists as to whether serum or plasma VEGF (S-VEGF, P-VEGF) is the most appropriate surrogate marker of tumor angiogenesis. As healing wounds produce VEGF that can spill over into the circulation, we aimed to investigate the potential confounding effects of cancer surgery on both perioperative S-VEGF and P-VEGF levels and to evaluate their relationship with platelet count. S-VEGF, P-VEGF and platelet counts were measured in 23 patients undergoing esophageal cancer resection. Samples were taken preoperatively and six weeks following surgery. Seven patients were also sampled on postoperative days 1, 5 and 10. VEGF was assayed using a commercial enzyme linked immunosorbent assay. S-VEGF and P-VEGF both rose after surgery (S-VEGF; day 5: 1017 [446-1224] pg/mL and day 10: 1231 [626-2046] pg/mL versus pre-op: 329 [189-599] pg/mL. P-VEGF; day 1: 55 [46-104] pg/mL and day 10: 58 [20-154] pg/mL versus pre-op: 23 [13-46] pg/mL), falling towards preoperative levels by six weeks. Platelet count correlated with S-VEGF (rho=0.281; p<0.05, Spearman's rank) and P-VEGF (rho=0.330; p<0.01, Spearman's rank). Platelets may contribute to VEGF levels in plasma as well as in serum. The effects of surgery on S-VEGF or P-VEGF levels are mainly transient. Care must be exercised when interpreting circulating VEGF levels in the early postoperative period.

Aged↗
PubMed2005

[APACHE II, APACHE III, SOFA scoring systems, platelet counts and mortality in septic and nonseptic patients].

BACKGROUND: The aim of the current prospective study was to examine the prognostic value of APACHE II, APACHE III (Acute Physiology and Chronic Health Evakuation II and III) and SOFA (Sepsis-related Organ Failure Assessment) scores and platelet counts in septic and nonseptic patients hospitalized and treated in ICU units. METHODS: One hundred and twenty ICU patients were included in this study. Patients were grouped as septic survivors, septic nonsurvivors, nonseptic survivors and nonseptic nonsurvivors. The SOFA, APACHE II and III scores, and platelet counts were recorded at the admission in the ICU units and discharge.from the hospital. RESULTS: Patients were grouped as septic survivors (n=42), septic nonsurvivors (n=14), nonseptic survivors (n=48) and nonseptic nonsurvivors (n=16). The highest SOFA, APACHE II and III scores and the lowest platelet counts were observed in septic nonsurvivors when compared with the other patient groups. All score values and platelet counts were found to be significant in prediction of mortality in septic patients. CONCLUSIONS: According to our results obtained in septic and non-septic patients, we concluded that SOFA, APACHE II and III scores and platelet counts might be used in the prediction of mortality in septic patients.

APACHE↗
PubMed1995

The association of the platelet count and the peripheral CD8+ cell count in Japanese HIV-infected hemophiliacs.

To determine the factors involved in the pathogenesis of thrombocytopenia frequently found in human immuno-deficiency virus (HIV) infection, we studied the clinical and laboratory findings of 35 Japanese HIV-infected hemophiliacs regarding their association with thrombocytopenia. Seventeen HIV-positive patients were thrombocytopenic. They had fewer CD4+ cells and were in more advanced stages of the disease, compared with the 18 patients without thrombocytopenia. We carried out the stepwise regression analysis on 32 patients in the early stage of HIV infection, with the platelet count as the dependent variable, and with the CD8+ cell count, serum cholinesterase, alanine aminotransferase (ALT), CD4+ cell count and white blood cell count as explanatory variables. The CD8+ cell count, serum cholinesterase, and ALT were entered into the regression model as explanatory variables of the platelet count with statistical significance. A positive linear correlation in these 32 patients between the CD8+ cell count and platelet count (r = 0.50, P < 0.01) was noted. We conclude that the decrease of the CD8+ cell count may play a role in the pathogenesis of thrombocytopenia in Japanese hemophiliacs in the early stage of HIV-infection.

Adult↗
PubMed1982

Effect of low-dose heparin on the platelet count.

Thrombocytopenia has been associated with the use of intravenous heparin, but the effect of low-dose, subcutaneously administered heparin on the platelet count is not known. We monitored the platelet counts in 50 patients admitted to a coronary care unit and given low doses of heparin for at least three days. No patient had thrombocytopenia during an observation period of 15 days. We conclude that routine measurement of the platelet count is unnecessary when low-dose heparin is used in this patient population.

Adult↗
PubMed1982

Platelet counts in blood taken from femoral artery, femoral vein, cubital vein, and arteriovenous fistula.

In 20 patients under regular dialysis with an arteriovenous fistula in one forearm, platelet counts were measured in blood taken simultaneously from the cubital vein, the arterialized vein near the site of anastomosis, the femoral vein, and the femoral artery. Samples of blood from the fistula and from the cubital vein of the opposite limb were taken with and without stasis. The highest values were found in blood taken from the cubital vein without stasis. Platelet counts were identical in femoral artery and vein, but were 4.8 and 4.9%, respectively, lower than the cubital vein values. Platelet counts from fistula blood taken without stasis were 13.7% lower than in the cubital vein. Platelet counts were lower when samples of blood were taken with stasis: 11.2% in the cubital vein, 7.4% in fistula blood. The awareness of these differences is of practical importance for platelet behavior studies.

Arm↗
PubMed1993

Elevated platelet count as a cause of abnormal von Willebrand factor multimer distribution in plasma.

Twelve of 19 patients with myeloproliferative disorders showed a decrease of absence of the largest multimers of plasma von Willebrand factor (vWF) that correlated with elevated platelet counts but not with leukocyte counts. This suggested that platelets, rather than leukocytes, may be associated with the pathogenesis of the acquired vWF abnormality seen in these patients. To examine the hypothesis further, we studied 12 patients with reactive thrombocytosis after splenectomy. Increased platelet count (> 5 x 10(11)/L) after splenectomy was associated with vWF abnormalities indistinguishable from those detected in patients with myeloproliferative disorders. Accordingly, there was an inverse correlation between proportion of large vWF multimers and platelet, but not leukocyte, number: normalization of the platelet count was accompanied by restoration of a normal vWF multimeric pattern. These findings suggest that an increase in the number of platelets circulating in blood may favor the adsorption of larger vWF multimers onto the platelet membrane, resulting in their removal from the circulation and subsequent degradation.

Adult↗
PubMed1997

Impala, Aepyceros melampus, platelets: count, morphology, and morphometric observations.

There is little published information regarding the platelets of impala (Aepyceros melampus). In this study we determined the platelet counts of 12 healthy adult male impalas and describe the morphology of the platelets. The platelet counts of the animals are high. Although the platelets appear to be extremely small, they have the characteristic ultrastructure of the platelets of the family Bovidae. They have few but prominent alpha-granules. Other cytoplasmic inclusions are the dense bodies, microtubules, mitochondria, and glycogen. There is no surface-connecting canalicular system present.

Animals↗
PubMed1994

Serum lactate dehydrogenase and platelet count predict survival in thrombotic thrombocytopenic purpura.

A significant number (some 20%) of patients with thrombotic thrombocytopenic purpura do not respond to standard therapy and die. We reasoned that early identification of those who are likely to fail standard therapy would allow the rational introduction of other treatment modalities. To this end we prospectively evaluated 27 consecutive patients, examining serum LDH levels and platelet counts as markers of disease activity and as predictors of outcome. All patients were treated, according to a written protocol, with high volume plasma exchange (35 ml/kg), prednisone, aspirin, and persantine. Twenty-one of the 27 patients (78%) are alive following therapy. Initial LDH and platelet values did not distinguish between the survivors and nonsurvivors. However, by day 3 of therapy both LDH levels and platelet counts differed significantly between the two groups. Mean day 3 LDH level for survivors was 364 units/L, and for nonsurvivors, 891 units/L (P < 0.005). Mean day 3 platelet count for survivors was 119,000/microL, and for nonsurvivors, 46,000/microL (P < 0.005). Receiver Operator Characteristic curves were constructed and assessed by calculating the area under the curve. This analysis showed that LDH is able to discriminate survivorship one day earlier than platelet count. Both LDH level and platelet count are excellent predictors of survival, under standard therapy, after 3 days of treatment. Early identification of those at greatest risk will facilitate the early institution and evaluation of alternative methods of treatment, such as splenectomy, intravenous Ig, or Vincristine.

Adult↗
PubMedDate not supplied

[Changes in platelet concentrates from dogs due to storage. I. Platelet count in in vitro function].

The possibility of storage of canine platelet concentrates (PC) was investigated using PC from dogs which were obtained with an automatic cell separator in C4-cell separation sets with low gasdiffusionable Polyvinylchlorid (PVC) storage containers or in C4L-sets developed for storage with high gasdiffusionable Polyolefin (PO) containers, respectively. The storage was carried out for a period of 10 days under permanent agitation at 22 degrees C (C4/22 degrees C, n = 10; C4L/22 degrees C, n = 11) or at 4 degrees C (C4L/4 degrees C, n = 6), respectively. Measurements were done directly after production of the PC, after 6 hours and then daily during the 10-day storage period. In the first part of this paper the results of platelet count (determined automatically with a blood cell differentiation automat and visually), the number of platelet aggregates, the mean platelet volume (MPV) as well as the platelet function with regard to the platelet aggregation induced by collagen or ADP and the resonance-thrombogram (RTG) are presented. The platelet count, measured automatically as well as visually, remained preponderantly constant over the complete storage time in all storage conditions. Dependent on the storage conditions--especially under storage at 22 degrees C--an increase of the number of platelet aggregates and a decrease of MPV was determined. In addition, the loss of platelet function measured by aggregation induced by collagen as well as by ADP showed a significant dependency of storage conditions. The stored platelets lost their ability to aggregate under C4/22 degrees C-conditions after a storage period of 2 days, under C4L/22 degrees C-conditions after 4 days and under C4L/4 degrees C-conditions not before 8 days of storage. Previous resuspending of platelets in fresh plasma delayed the loss of platelet function. Because the loss of platelet function described in the RTG became significant at nearly the same point in time, a storage of canine PC under corresponding conditions can be recommended for upto 2 days (C4/22 degrees C), for 4 days (C4L/22 degrees C) or 8-10 days (C4L/4 degrees C), respectively.

Adenosine Diphosphate↗
PubMed2004

The effects of 5-aza-2'-deoxycytidine (Decitabine) on the platelet count in patients with intermediate and high-risk myelodysplastic syndromes.

5-Aza-2'-deoxycytidine, a DNA-hypomethylating agent, can induce clinical remissions in patients with high-risk myelodysplastic syndromes (MDS). During treatment an increase in platelet count is frequently the first positive event to be seen. In this study, we analyzed the platelet response of patients with high-risk MDS on low-dose 5-aza-2'-deoxycytidine therapy. We evaluated 162 from the 170 patients entered in three consecutive Phase II studies. One hundred twenty-six of them were thrombocytopenic at start of the therapy. All patients had an IPSS risk score of Intermediate I or higher. A rise in platelet count preceded a good trilineage response. In 58% of the thrombocytopenic patients a platelet response was already seen after one cycle of therapy. During therapy 69% of the patients with a low platelet count showed a response. Due to disease progression the final response rate was 63% in thrombocytopenic patients. No correlation was found between the platelet response and either the presence or absence of an adequate number of megakaryocytes or serum thrombopoietin levels. However, platelet response strongly predicted for overall survival (P < 0.0001). 5-Aza-2'-deoxycytidine has a clinically significant, often long lasting, effect on the platelet count in a substantial number of high-risk MDS patients.

Adult↗
PubMed1992

Proficiency testing of platelet counting in Ontario.

Proficiency testing results provide data for interlaboratory comparisons. The Laboratory Proficiency Testing Program of Ontario, Canada, has tested platelet counting for a decade and other hematology parameters for 15 years. Despite the fact that all testing programs are compromised by the type of testing material used, for platelet count testing, conclusions are possible. The data indicate that most laboratories in Ontario have greater difficulty performing reproducible platelet counting as compared with other components of hematologic cytometry. A major contributor to this shortfall is the method used by the laboratory. It was not a surprise that manual counting had a high coefficient of variation. Unexpectedly, the semiautomated methods used in the mid-1980s also displayed a high coefficient of variation.

Humans↗
PubMed2001

Effect of Carmeda BioActive Surface coating versus Trillium Biopassive Surface coating of the oxygenator on circulating platelet count drop during cardiopulmonary bypass.

An investigation was conducted to evaluate the effect that surface coating of the hollow-fiber membrane oxygenator had on circulating platelet count drop during cardiopulmonary bypass (CPB). Sixty patients undergoing non-emergency myocardial revascularization for coronary artery disease were randomly divided into two groups. Group one (n = 32) received the Carmeda-coated Maxima-Plus PRF oxygenator while the patients in Group two (n=28) received the Trillium-coated Affinity oxygenator during CPB. The net platelet count drops for the pump specimen (15-20 min after the initiation of bypass) for the Carmeda and the Trillium groups were 3.6 +/- 15.8% and 6.2 +/- 10.2%, respectively. The net platelet count drop for the warming specimen for the Carmeda and the Trillium groups were 2.9 +/- 19.4% and 0.5 +/- 11.0%, respectively. There were no statistically significant differences between the groups. The authors conclude that using either the Carmeda-coated Maxima-Plus PRF oxygenator or the Trillium-coated Affinity oxygenator afford similar benefits in regards to preserving circulating platelet counts during bypass.

Aged↗
PubMed1985

Platelet adhesion to subendothelium--effect of shear rate, hematocrit and platelet count on the dynamic equilibrium between platelets adhering to and detaching from the surface.

The adherence of human 3H-adenine-labeled platelets to rat subendothelium was quantitated using a rotating probe device. Platelet adhesion increased in relation to the rotation time, reaching a plateau value in about 4-6 min without any further increase. A non-linear fitting analysis of experimental data allowed calculations of initial rate and plateau value of platelet adhesion. Increasing the shear rates (from 35 to 150 sec-1) or the hematocrit (from 10% to 40%), both the adhesion rate and the plateau value were increased. When different platelet concentrations were used the adhesion rate and the plateau calculated increased with platelet concentration. Different plateau values were obtained in the experimental conditions considered. This suggests that the plateau was not reached for the complete occupation of the subendothelial surface by the adherent platelets. Experiments using two different vessels rotated in the same platelet suspension or, viceversa, the same vessel rotated successively in two fresh platelet suspensions, showed that the plateau was not determined by reduced platelet reactivity. Rotating the same vessel first in radiolabeled platelets, until the plateau was reached, and secondly in non labeled platelets, or viceversa, showed that the plateau was indeed a dynamic condition where the number of platelets adhering and detaching reached equilibrium. These observations suggest that the platelet adhesion to subendothelium is the final equilibrium of two platelet fluxes, one adhering to the surface and another detaching from the surface.

Animals↗
PubMed2000

Impact of high-dose corticosteroid therapy for patients with HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome.

OBJECTIVE: The purpose of this study was to determine whether corticosteroid administration to patients with antepartum HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome would alter laboratory values diagnostic for the disease. STUDY DESIGN: Cases of 37 women with antepartum HELLP syndrome managed between March 1995 and July 1999 were reviewed. Patients were classified on the basis of exposure to corticosteroids and to the dose used. Group 1 did not receive corticosteroids. Group 2 received a standard corticosteroid dosage regimen for promotion of fetal lung maturation. Group 3 received a high-dose corticosteroid regimen of >24 mg/d (most frequently 10 mg dexamethasone as an intravenous bolus dose every 6 hours for 2 doses followed by 6 mg as an intravenous bolus dose every 6 hours for 2 to 4 doses). Antepartum changes in laboratory values from diagnosis to delivery were evaluated by means of the Kruskal-Wallis test. RESULTS: Eleven patients did not receive corticosteroids, 15 were given a standard dose, and 11 received high-dose therapy. For each laboratory value assessed (platelet count, aspartate aminotransferase activity, and lactate dehydrogenase activity), the corticosteroid groups differed significantly from the no-treatment group (P </=.002 for all). A further, significantly greater improvement in platelet count was noted between the high-dose group (81%) and the standard-dose group (17%; P =.04). The interval from diagnosis to delivery was also longer for patients treated with the high-dose protocol (51 +/- 25 hours) than for both those treated with a standard regimen (26 +/- 20 hours) and those who received no treatment (13 +/- 11 hours; P <. 001). CONCLUSION: Administration of corticosteroids to patients with antepartum HELLP syndrome improves platelet count, reduces liver enzyme abnormalities, and prolongs latency to delivery in a dose-dependent manner. Higher doses of corticosteroid than those traditionally prescribed for promotion of fetal pulmonary maturation should be considered for maternal and fetal benefits in cases of severe preeclampsia.

Adult↗
PubMed2001

Low platelet count in a 22q11 deletion syndrome subtype of schizophrenia.

BACKGROUND: 22q11 Deletion Syndrome (22qDS) is a genetic syndrome associated with various physical features and schizophrenia. Some reports have identified thrombocytopenia (platelet count < 150 x 10(9)/l) in individuals with 22qDS, especially children. We investigated whether adults with 22qDS and schizophrenia (22qDS-SZ) have lower platelet counts than other patients with schizophrenia (SZ). METHOD: Complete blood counts (CBC) were recorded from medical records for 18 22qDS-SZ and 60 SZ subjects. Five CBCs per subject were randomly selected and used to calculate a within-subject mean for analyses. RESULTS: 22qDS-SZ subjects had significantly lower mean platelet counts than comparison SZ subjects (142.2 x 10(9)/l versus 282.5 x 10(9)/l, t = -11.5, p < 0.0001). Ten 22qDS-SZ (55%) and no comparison subjects had thrombocytopenia. CONCLUSIONS: These results suggest that thrombocytopenia may be a common feature of 22qDS and that low platelet counts may comprise a readily available screening criterion to help identify this genetic syndrome among adults with schizophrenia.

Adult↗
PubMed1985

Accuracy of low platelet counts on the Coulter S-Plus IV.

Recent improvements have occurred in the flagging criteria for erroneous platelet counts on Coulter S-Plus series instruments. The authors tested the accuracy of the S-Plus IV on over 400 patient samples with low platelet counts (less than 50,000/microL) as compared with phase microscopy. Only a small number of samples gave discrepant results (difference greater than 10,000/microL), and, when investigated, most often were found to be due to erratic phase microscopy results. Approximately one-third of all low platelet counts in our laboratory were flagged ("error code 10") by the instrument and required determination by phase microscopy. In addition, to prevent erroneous results due to giant platelets or microcytic red blood cells, the platelet histogram should be inspected for return to baseline at 20 cubic micrometers (fL).

Evaluation Studies as Topic↗