Bone marrow megakaryocytes, soluble P-selectin and thrombopoietic cytokines in multiple myeloma patients.

The expression of adhesion molecules and other cell-surface molecules is substantial in the communication between plasma cells and bone marrow microenvironment, and may lead to increased proliferation of myeloma cells. Many of the cytokines involved in multiple myeloma (MM) pathogenesis, e.g. thrombopoietin (TPO) and interleukin-6 (IL-6), play a pivotal role in different developmental stages of megakaryocytopoiesis and thrombopoiesis. The principal aim of our study was to explore the relationship between thrombopoietic cytokines, megakaryocytes (MKs) and soluble P-selectin (sP-selectin) levels in MM patients before and after anti-angiogenic treatment. Forty-four patients (20 female and 24 male) with a newly diagnosed MM were examined in three groups, following a division based on the International Staging System, ISS. Plasma levels of TPO, IL-6 and soluble P-selectin (human sP-selectin) were measured by means of ELISA. Bone marrow specimens were studied to determine the number of MKs and the so-called "naked nuclei" (NN), as well as the expression of platelet-derived growth factor (PDGF). The comparison revealed a significantly higher concentration of cytokines and sP-selectin in newly diagnosed MM patients compared to healthy volunteers: for TPO, p=0.01, IL-6, p=0.0005 and sP-selectin, p=0.00008, respectively. Marked differences were observed in the concentration of sP-selectin, expression of PDGF and MKs counts between patients with MM stage I and MM stage III. Statistically meaningful correspondences were also found between MKs versus TPO, NN versus TPO, as well as MKs versus MPV, p=0.009, p=0.004 and p=0.0005, respectively. Furthermore, the analysis exhibited some statistically meaningful divergences between initial concentrations of sP-selectin in subgroups with different response after chemotherapy. The initial concentration of sP-selectin in the group of MM patients with complete or partial remission stood at 31.86 ± 6.13 ng/ml. In the remaining patients (stable disease), the concentration of sP-selectin amounted to 35.15 ± 7.23 ng/ml (p=0.048). We found a correlation between sP-selectin and IL-6 (ρ=0.57, p=0.0004), TPO and IL-6 (ρ=0.46, p=0.001) as well as sP-selectin and TPO (ρ=0.36, p=0.043), and sP-selectin and PDGF (ρ=0.36, p=0.03). Our study has eventually demonstrated that sP-selectin, as a marker of platelet activation, could be a useful marker of maximum response to therapy. Its strong association with another marker like PDGF-AB could further lead to the development of new combinational therapeutic strategies of anti-angiogenic therapy in MM patients.

Multiplexing analysis of the polyspecific intrathecal immune response in multiple sclerosis.

Intrathecal synthesis of the antibodies specific to neurotrofic viruses: measles (M), rubella (R), Varicella-Zoster (Z), and/or H. simplex (H), known as "MRZH-reaction" plays important diagnostic role in multiple sclerosis (MS). Whereas the analysis of the oligoclonal IgG bands provides high sensitivity, the MRZH-reaction shows high specificity, and hence these methods complement each other. For the first time we applied multiplexing bead-based technology to simultaneously analyze cerebrospinal fluid (CSF) and serum concentrations of antibodies against these viruses, and to calculate the antibody specific indices (ASI's). The method shows reasonable precision: intra-assay, 2.9-6.7%, and inter-assay, 2.0-3.2%. The results are comparable with these obtained with other methods (ELISAs), including two runs of the certified external quality control schemes. Eighty-one percent of the MS cases (n=27) and none of the sex- and age-matched controls (n=14), except one subject with "borderline" anti-measles ASI of 1.5, showed intrathecal synthesis of IgG against at least one of the viruses discussed. The ratios of the MRZH-positive cases in the MS group were: 12/22 for M, 12/19 for R, 13/26 for Z, and 7/26 for H. We conclude that the multiplexing technology can be applied as a tool to study the intrathecal immune response in the diagnosis of MS.

Platelet expression of CD62P in hypotrophic newborns.

BACKGROUND: Hypotrophic newborns demonstrate a reduced blood platelet count and therefore may have haemostasis disorders. The antigen density of CD62P on the surface of platelets may indicate the activation of blood platelets. MATERIALS AND METHODS: We have studied 31 hypotrophic newborns, and have divided these into two groups: weighing less than the 5th centile and between the 5th and 10th centiles. The antigen density of CD62P was calculated according to the procedure recommended by DAKO QIFIKIT. RESULTS: Hypotrophic newborns exhibited a median 22 000 of CD62P per platelet. There is a distinct gender difference (female median 29 768, male median 19 044 of CD62P per platelet, p = 0.001). Newborns below the 5th centile demonstrated a median 30 000 of CD62P per platelet, whereas between the 5th and 10th centiles - a median 18 700. A negative correlation (R = -0.53, p = 0.002) was found between the antigen density of CD62P and birth weight. CONCLUSION: Hypotrophy affects the expression of CD62P. There is a negative correlation between the antigen density of CD62P and birth weight.

[Prothrombotic aldosterone action--a new side of the hormone]. / Prozakrzepowe dzialanie aldosteronu--nowe oblicze hormonu.

Recent studies have focused on a new wave of interest in aldosterone due mainly to its growing profile as a local messenger in pathology of the cardiovascular system, rather than its hormonal action. In the last few years strong evidence for a correlation between raised aldosterone level and haemostasis disturbances leading to increased risk of cardiovascular events has been provided. It has been demonstrated that aldosterone contributes to endothelial dysfunction, fibrinolytic disorders and oxidative stress augmentation. It was also shown that chronic aldosterone treatment results in enhanced experimental arterial thrombosis. Our study in a venous model of thrombosis in normotensive rats confirmed that even a short-lasting increase in aldosterone level intensified thrombus formation. One-hour aldosterone infusion shortened bleeding time; increased platelet adhesion to collagen; reduced tissue factor, thrombin activatable fibrinolysis inhibitor, and plasminogen activator inhibitor; and increased plasminogen activator plasma level. A fall in plasma nitric oxide metabolite concentration with a decrease in aortic nitric oxide synthase mRNA level was also observed. Moreover, aldosterone increased hydrogen peroxide and malonyl dialdehyde plasma concentration and augmented NADPH oxidase and superoxide dismutase aortic expression. Therefore, the mechanism of aldosterone prothrombotic action is multiple and involves primary haemostasis activation, procoagulative and antifibrinolytic action, NO bioavailability impairment and oxidative stress augmentation. The effects of aldosterone were not fully abolished by mineralocorticoid receptor blockade, suggesting the involvement of alternative mechanisms in the prothrombotic aldosterone action.

Thrombopoiesis in small for gestational age newborns.

Thrombocytopenia in small for gestational age (SGA) newborns may be due to placental vascular pathology, fetal consumptive coagulopathy and platelet destruction, local imbalance of thromboxane A2 causing placental vasoconstriction and platelet aggregation. Thrombopoiesis in SGA newborns is poorly recognized. In 61 SGA newborns we evaluated thrombocytopoiesis in relation to gender and the rate maturity expressed as <5th percentile and <10th percentile. Female newborns demonstrated higher thrombopoietin (TPO) level at 92.06 pg/ml than male newborns at 79.81 pg/ml. Newborns less developed <5th percentile, showed increased TPO level of 92.0 pg/ml in comparison to <10th percentile of 78.0 pg/ml. This observation is more pronounced in female newborns. Contrary to our expectations we did not find any statistically significant differences in the percentage of reticulated platelets (PLRET) and platelets count in relation to gender and <5th percentile or <10th percentile. We can postulate intrauterine hypoxia is responsible for the increase of erythropoietin and impairment of thrombopoiesis in SGA newborns.

[A new look at platelets and microparticles, including their role in haemostatic disorders and progression of neoplastic disease]. / Nowe spojrzenie na plytki krwi i mikroplytki z uwzglednieniem ich roli w zaburzeniach krzepniecia i progresji choroby nowotworowej.

Platelets (PLT) are the smallest yet highly reactive components of the circulatory system. Microvesicles (platelet-derived microvesicles - PMV), also known as microparticles or microplatelets (platelet-derived microparticles - PMP), are released from platelets upon stimulation by thrombin, collagen or others platelet agonists. Both PLT and PMP play a role in haemostasis and mediate signal transmission between cells, especially cancer cells, thus modulating their functions. Moreover, these two platelet populations participate in transcellular exchange of information, affect immune responses and angiogenesis, which may facilitate tumour growth and development of distant metastases. Their role in tumour progression has been recognized, but the mechanism of their action remains still unclear. Assessment of PMP as a diagnostic and prognostic marker in various disorders is currently a subject of intense investigation.

[Platelets haemostatic in patients with multiple myeloma]. / Hemostaza plytkowa u chorych na szpiczaka mnogiego.

Multiple myeloma (MM) is a type of disseminated cancer which derive plasma cells that are immune system cells in bone marrow and produce monoclonal protein. It represents approximately 1% of all cancers, but recent statistics indicate both increasing incidence and earlier age of onset. Haemostatic disorders are an important clinical problem in patients with MM. The most common disturbances symptoms are bleeding and deep-vein thrombosis can due to platelet dysfunction, inhibition of fibrin and increased clearance of coagulation factors connected with monoclonal protein presence. The aim of study is a presentation of disturbances haemostatic in patients with MM, which make up important clinical and diagnostic problems.

The effect of gestational age on platelet surface expression of CD62P in preterm newborns.

Hemostasis in preterm newborns is characterized by low reserve functional capacity with special reference to the presence of such risk factors as asphyxia or infection. Platelets play vitally important role in hemostasis. Expression of CD62P is a marker of stimulated or activated blood platelets. The study involved a group of 16 preterm newborns, five girls and 11 boys. DAKO QIFIKIT was applied to calculate the number of these antigens. The mean CD 62P expression was found to be 23,792 per platelet. Correlation was found between antigen density and gestational age r = 0.954, p = 0.01. Evident deficit of P-selectin on the surface of platelets in preterm newborns may be at least in part responsible for platelet dysfunction, with special reference to interaction between circulating leukocytes and combating infection.

Platelet-derived microparticles and platelet count in preterm newborns.

OBJECTIVE: Does formation of platelet-derived microparticles correspond to platelet activation? METHODS: The study was performed in 51 preterm newborns, 25 girls and 26 boys. The control group consisted of 55 term newborns, 25 girls and 30 boys. Blood samples were collected from the umbilical artery. The percentage of platelet-derived microparticles and platelet count were determined using flow cytometric analysis based on the CD61-positive antigen. RESULTS: The percentage of platelet-derived microparticles was higher in preterm newborns (5.46) in comparison to term newborns (4.22, p < 0.01). We found 4.61% of platelet-derived microparticles in preterm female newborns and 6.28% in preterm boys (p < 0.0070). The platelet count was 256 x 10(3) microl in girls and 238 x 10(3) microl in boys. Female healthy term newborns presented higher values of platelet-derived microparticles (4.4%) than male newborns (4.07%, p = 0.4725, table 1). The platelet count in girls was found to be 308 x 10(3) microl and in boys 270 x 10(3) microl. CONCLUSIONS: Higher percentage of platelet-derived microparticles in preterm newborns may provide a compensatory mechanism for the hemostatic system.

Megakaryocytes and platelets in experimentally induced renovascular hypertension (2K1C) in rats.

INTRODUCTION: Hypertension is one of the most frequently occurring diseases worldwide. Approximately 10% of the population with hypertension reveals the secondary type of the disease. The aim of the study was to evaluate the megakaryocyte-platelet system in the course of renovascular hypertension. MATERIAL/METHODS: An experimental model of hypertension in rats according to Goldblatt was used in the study. The experimental material (blood, bone marrow) was collected in the 4th, 8th, and 16th weeks of the study. Bone marrow megakaryocytes (MKs) were evaluated using immunohistochemical and morphometric methods. Blood platelets were analyzed based on their count (PLT) and mean volume (MPV). Plasma thrombopoietin (TPO) concentration was also assessed. RESULTS: The investigation showed increased numbers of MKs 16 weeks after partial unilateral ligation of the renal artery. Statistically significant increase in platelet count, platelet mass, and the number of MK naked nuclei (NKs) as well as elevation of the circular deviation of the nuclei (CDN) of MKs accompanied the changes. MPV and TPO concentration did not change during the experiment. There was significant positive correlation between the increase in blood pressure and the numbers of MKs and NKs. The number of MKs correlated positively with PLT and CDN. Although TPO plasma level did not change significantly, there was marked negative correlation between plasma TPO concentration and PLT. CONCLUSIONS: Although features of intensified platelet turnover were not observed, on the basis of the study it can be assumed that the megakaryocytic system undergoes changes in the course of renovascular hypertension. This can contribute to blood platelet production and the development of possible hypertension complications.

[Platelet- derived growth factor--the construction, role and it's receptors]. / Plytkopochodny czynnik wzrostu--budowa, rola i jego receptory.

CONSTRUCTION: The platelet- derived growth factor (PDGF) is a small protein which is produced by many cells. PDGF was originally identified in platelets and in serum. It is a dimeric molecule consisting of disulfide- bonded, structurally similar A- and B- polypeptide chains. There are four isoforms of PDGF: PDGF A, PDGF B, PDFG C and PDGF D. There are purified from the alpha-granules of the platelets. ROLE: PDGF is a critical regulator of mesenchymal cell migration and proliferation. It is essential for angiogenesis, embryogenesis and cancer development and progression. Clinical studies reveal that aberrant expression of PDGF and its receptors is often associated with a variety of disorders including atherosclerosis, fibroproliferative diseases of lungs and kidneys. RECEPTORS: There are two structurally related PDGF- receptors, each with its own variation in signaling mechanism. Each subunit of PDGF binds one receptor subunit, leading to receptor dimerization. The receptors are tyrosine kinases. PDGFR alpha binds all types of isoforms. PDGFR beta can bind only polypeptide B.

[Cell adhesion molecules and their participation in the process of inflammation and cancerogenesis]. / Czasteczki adhezyjne oraz ich udzial w procesie zapalnym i nowotworowym.

Cell adhesion molecules (CAMs) determine the integral part of protein of cell membranes. CAMs mediate in the reception and the transformation of the information from the external environment. Then CAMs mediate in the transfer of the information in the from of the signal to each fine structure. The inflammation process, in which the whole family of cell adhesion molecules takes place, is a state which leads to cancer or tumor metastasis. We observe in the cancerogenesis process a disturbance of the cell adhesion and proliferation, as well as scaled-down integrality between cell and intercellular matrix. CAMs function suggests that they play a very important role in inflammation the neoplasia process. It use can be found in the early pathogenesis cancer disease.

[Cerebrospinal rhinorrhea--etiology, clinical signs and laboratory diagnosis]. / Plynotok nosowy--etiologia, objawy kliniczne oraz postepowanie diagnostyczne.

Last studies have shown unsatisfactory diagnosis of cerebrospinal rhinorrhea. Although the majority of cerebrospinal (CSF) fistulas in the anterior skuli base are traumatic in nature, the minority is non-traumatic or primary. The authors have made an attempt of presenting on the basis of scientific reports of the physiopathology, imagin and diagnosis of cerebrospinal fluid leaks. This article introduces rapid, accurate and non-invasive biochemical methods for detection of cerebrospinal fluid leakage using combined determination of glucose, beta-trace-protein and beta-2-transferrin in secretion and serum. There are presented new invasive techniques for detection and localization of the cerebrospinal fluid leaks: CT and CT with contrast, MR cisternography and MRI cisternography in combination with single photon emission tomography. Finally, discusses different opinion in the management of the problem once it occurs.

[SP-selectin and beta-TG as serum markers of platelet activation in menopausal women with depression]. / SP-selektyna i beta-tromboglobulina jako osoczowe markery aktywacji plytek krwi u kobiet z depresja w okresie menopauzy.

UNLABELLED: During activation, blood platelets (PLT) release a number of micromolecular compounds, of which P-selectin and beta-thromboglobulin (beta-TG) are considered the major markers of the activation. The activated platelets and the released micromolecular compounds actively participate in thromboembolic disorders frequently observed in menopause. Low estrogen level in menopausal women is a common cause of depressive disorders. The aim of the study was to compare the state of PLT activation in menopausal women with and without depression. The assessment of PLT activation was based on the concentration of sP-selectin and beta-TG as serum markers of the activation. MATERIAL AND METHODS: Among 65 menopausal women examined, 16 (approx. 25%) had depression. PLT activation was assessed on the basis of sP-selectin and beta-TG levels. The investigation was performed in the low-platelet citrate serum obtained from venous blood collected onto anticoagulant. The levels of beta-TG and sP-selectin were determined using the immunoenzymatic method, with ELISA Kit reagents. RESULTS: In all the women, both with and without depression, the levels of beta-TG and sP-selectin several times exceeded the accepted norms. The concentration of beta-TG was statistically significantly higher (p < 0.05) in women with depression as compared to those with no depressive disorders. CONCLUSIONS: Menopausal women suffering from depression show enhanced intravascular platelet activation. High beta-TG level in women with depression indicates higher risk of thromboembolic disorders in comparison with depression-free women in menopause.

[Early diagnosis of bladder carcinoma]. / Wczesna diagnostyka raka pecherza moczowego.

Asymptomatic erythrocyturia is an early symptom of urinary tracts and kidney diseases, including bladder carcinoma. The aim of the research was to compare the diagnostic validity of the cytological urine analysis and the DNA flow cytometry in detecting cancer cells in urine and bladder washings, taken from patients with asymptomatic erythrocyturia, as an early symptom of the bladder carcinoma in situ. The research was conducted on a group of 48 patients (32 male, 16 female, aged 28-55) with asymptomatic erythrocyturia, caused, in 16 cases, by bladder carcinoma in situ, in 18 cases, by bladder carcinoma in situ with urinary tracts infection, and in 14 cases, by the infection alone. Flow cytomery showed a higher sensitivity and a higher negative prediction value in detecting cancer cells in bladder washings. Flow cytometry analysis of DNA and phase S is used for detecting early disturbances in the cell cycle which result in aneuploidia, which is impossible to detect in cytological analysis. However peculiarity and positive prediction value were the same (100%) in both methods. On the basis of the research it has been proved that asymptomatic erythrocyturia classifies patients for further, in-depth diagnostic examination for the presence of bladder carcinoma in situ. Furthermore, morning urine and bladder washings analysis, which are non-intrusive tests, are an outstanding diagnostic material for screening for this disease. Detecting aneuploidia with flow cytometry can be an early-detection screening test for bladder carcinoma, while the cytological tests should still be used for confirming the diagnosis.

[Does colorectal cancer clinical advancement and surgical treatment affect platelet factor 4 concentration]. / Czy stopien zaawansowania raka jelita grubego i leczenie chirurgiczne wplywaja na zmiany stezenia czynnika plytkowego 4.

UNLABELLED: The aim of the present study was to determine platelet factor 4 (PF 4) concentration, as a marker of platelet activation, in patients with colorectal cancer (CRC), depending on the clinical advancement of carcinoma and surgical treatment. MATERIAL AND METHODS: We investigated 21 patients with CRC before the surgery (A0) and three days (A1) and twelve days (A2) after the surgery. The patients were divided into three groups, according the clinical advancement--I, II, III (Hutter's classification). The control group (C) consisted 20 healthy subjects. PF 4 concentration was determined using the immunoenzymatic method (ELISA). RESULTS: Patients with CRC before the surgery had a statistically significantly increased PF 4 concentration versus the control group (p<0.001). The highest PF 4 concentration was observed in patients without metastases (I degree advanced disease). Three days after the surgery PF 4 concentration decreased slightly in patients with III degree advanced disease. Twelve days after surgery (A2) it was again observed an increase of PF 4 concentration in patients with II and III stage of advancement. CONCLUSION: Results of the study confirm that platelets are involved in development of cancer and indicate significantly that surgical treatment applied in this patients affects platelet activation and morphological parameters. The lower PF 4 concentration in patients with CRC with metastases (II and III group) confirm that more activity platelets play an important role in the metastases.

[Some parameters of platelet activation in patients with uremia before and after hemodialysis (HD)]. / Niektóre parametry aktywacji plytek krwi u chorych z mocznica przed i po hemodializie (HD).

Patients with uremia show a tendency for hemorrhagic diathesis and thrombi formation. These disorders have been attributed to functional abnormalities of platelet and their interaction with the vascular wall. The aim of the present study was to elucidate whether and how in patients with uremia, hemodialysis affects the level of platelet activation markers, i.e.: beta-TG and PF4, and whether the changes in the examined parameters depend on creatinine level and on the type dialysis membranes used during HD. The study involved 70 patients with uremia subjected to repeated hemodialysis and 70 healthy subjects. Prior to HD, we observed a decrease in PLT, and increase in beta-TG concentration and a drop in PF4 (p = 0.000), compared to control group. Immediately after the procedure a significant increase was observed in PLT and decrease in PF4 concentration, as well as a slight rise in beta-TG level, compared to the values obtained before HD. We also found statistically significant differences in beta-TG and PF4 concentrations prior to HD, irrespective of creatinine concentration, compared to control group. Only at creatinine concentration of 10.0-15.5 mg/dL, PLT differences significantly from PLT in control group. Following HD, creatinine-dependent statistically significant changes were noted in PLT, in comparison to the values obtained before the procedure. The analysis of platelet parameters revealed no statistically significant differences associated with the type of the dialysis membrane used for HD.

Does thrombopoiesis in multiple myeloma patients depend on the stage of the disease?

PURPOSE: Infiltration of the bone marrow by neoplastic plasmocytes in multiple myeloma (MM) patients might impair megakaryocytopoiesis. The aim of the study was to evaluate stage-dependent platelet count (PLT) and thrombopoietin (TPO) concentration in comparison to the control group. We also wanted to establish whether TPO might be recognized as a marker of the stage of the disease. MATERIAL/METHODS: The study group consisted of 41 patients (mean age 67.7) with newly diagnosed MM prior to treatment and categorized according to the Durie and Salmon diagnostic classification. The control group consisted of 30 healthy subjects (mean age 65.5). PLT, WBC, RBC and Hb were measured with the use of the haematological analyser. TPO was assayed with the use of ELISA and albumin with the use of the immunonephelometry method. The number of plasma cells in the bone marrow was evaluated in bone marrow smears under light microscopy. RESULTS: PLT was not statistically different as compared the control groups, but was stage-dependent. Thrombocytopenia was observed in the III stage of MM. TPO median was significantly higher in study group than in healthy subjects and it was increasing considerably with the stage of the disease. TPO concentration was negatively correlated with albumin and PLT. AUC for TPO was 0.9764. The number of plasma cells in the bone marrow was considerably increasing with the stage of the disease. CONCLUSIONS: PLT and TPO in MM patients were stage-dependent. Elevated TPO concentration in MM patients might be an unfavourable marker of the stage of the disease.

Expression of P-selectin (CD62P) on platelets after thrombin and ADP in hypotrophic and healthy, full-term newborns.

BACKGROUND: Hypotrophic newborns in comparison with eutrophic newborns demonstrate a reduced blood platelet count and therefore may have haemostasis disorders. Expression of P-selectin (CD62P) on the surface of platelets is a marker of stimulated, activated blood platelets. The ability of platelets to react can be determined after the addition of the following activators: strong (thrombin) and weak (ADP). MATERIALS AND METHODS: We studied 48 hypotrophic newborns, 25 females and 23 males, weighing less than the 10th centile and 55 healthy, full-term newborns, 25 females and 30 males. Expression of CD62P on the surface of platelets was examined in the native state, after the addition of thrombin or ADP. RESULTS: Hypotrophic newborns exhibited almost double the percentage of platelets expressing CD62P compared with the control group, 4.21% versus 2.88%. After the addition of thrombin, the percentage was 31.5% versus 12.5%, p < 0.001, whereas after the addition of ADP, the percentage was 9.54% versus 4.5%, p = 0.002. CONCLUSIONS: Hypotrophic newborns are capable of greater platelet activation in comparison with healthy term newborns. However, gender does not affect the expression of P-selectin.

Study of the mechanisms of aldosterone prothrombotic effect in rats.

INTRODUCTION: We investigated the role of primary haemostasis, fibrinolysis, nitric oxide (NO) and oxidative stress as well as mineralocorticoid receptors (MR) in acute aldosterone prothrombotic action. MATERIALS AND METHODS: Venous thrombosis was induced by stasis in Wistar rats. Aldosterone (ALDO; 10, 30, 100 µg/kg/h) was infused for 1 h. Eplerenone (EPL; 100 mg/kg, p.o.), a selective MR antagonist, was administered before ALDO infusion. Bleeding time (BT) and platelet adhesion to collagen were evaluated. The expression of nitric oxide synthase (NOS), NADPH oxidase, superoxide dismutase (SOD) and plasminogen activator inhibitor (PAI-1) was measured. NO, malonyl dialdehyde (MDA) and hydrogen peroxide (H(2)O(2)) plasma levels were assayed. RESULTS: Significant enhancement of venous thrombosis was observed after ALDO infusion. ALDO shortened BT and increased platelet adhesion. Marked increases were observed in PAI-1, NADPH oxidase and SOD mRNA levels. MDA and H(2)O(2) levels were augmented in ALDO-treated groups, and NOS expression and NO level were decreased. EPL reduced ALDO effects on thrombus formation, primary haemostasis, PAI-1 expression and MDA level. CONCLUSION: Short-term ALDO infusion enhances experimental venous thrombosis in the mechanism involving primary haemostasis, fibrinolysis, NO and oxidative stress-dependent pathways. The MR antagonist only partially diminished the ALDO effects, suggesting the involvement of additional mechanisms.