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Biomedical subjects

R Abbate

Publications and source records attributed to R Abbate.

At least 199 records · Page 11Linked to original sources
PubMed1980

Increased platelet aggregation due to plasma-aggregating activity. Identification of the responsible factors.

Platelet-poor plasmas (PPPs) from 52 out of 71 patients affected by different diseases and selected for increased amounts of circulating platelet aggregates, incubated at 37 degrees C for 30 min with control platelet-rich plasma (PRP; cross-matching test) induced the formation of platelet aggregates, stimulated the production of malondialdehyde and enhanced ADP-induced aggregation. 31 control PPPs were consistently negative at cross-matching test. Gel chromatography of plasmas on agarose 4% allowed the identification of four different fractions (A, B, C, D) provided with aggregating activity. Fraction A eluted at the void volume was to be identified with the von Willebrand factor, whereas B, C and D fractions, eluted at the same elution volumes as activated factor X were mainly composed of factor X (fraction B) and activated factor X (fractions C and D). Thrombin activity was absent in all the fractions provided with aggregating activity. Also, from control PPPs negative at cross-matching tests, the same fractions could be obtained, although of 5--10 times lower aggregating potency, thus explaining the negative cross-matching tests. These findings stress the role of some extraplatelet factors related to hypercoagulability in platelet hyperaggregability.

Adenosine Diphosphate↗
PubMedDate not supplied

Activity of dipyrone on intraplatelet arachidonic acid metabolism: an in vitro study.

The effects of dipyrone on platelet cyclooxygenase and lipoxygenase were investigated in vitro by the study of 1-14C arachidonic acid (AA) conversion by high performance liquid chromatography (HPLC) on washed platelets at seven different drug concentrations (from 5 to 300 micrograms/ml). The effects of dipyrone on thromboxane (TX) B2 generation from endogenous AA were also studied in platelet-rich plasma and in washed platelets by radioimmunoassay. In the study of 1-14C AA metabolism the inhibitory concentration (IC) 50 for TXB2 was 40 micrograms/ml. However, at the lowest drug concentration (5 micrograms/ml) a slight but significant inhibition was found (25.3%, P less than 0.001) and a complete one at 300 micrograms/ml. A relationship between TXB2 inhibition and log drug concentration was found (r = 0.97, P less than 0.001). Lipoxygenase (LO) activity showed an increase of 45.9% at 20 micrograms/ml and of 251.5% at the highest concentration (r = 0.97, P less than 0.001). The inhibition of TXB2 generation from endogenous AA by washed platelets was of the same order of magnitude of the inhibition of TXB2 production from exogenous 1-14C AA. Our results indicate that dipyrone affects intraplatelet AA metabolism at very low concentrations, however its activity, on a molar ratio basis, appears to be lower than that of other non-steroidal anti-inflammatory drugs.

Adult↗
PubMedDate not supplied

Venous thromboembolism in renal transplant recipients: high rate of recurrence.

Few data are available on the incidence of venous thromboembolism occurring in renal transplant recipients and optimal duration of oral anticoagulant therapy after thrombotic episode. Our study was performed to evaluate the risk of thrombosis recurrence in patients developing a first episode. Among 484 renal transplant patients 34 (7%) developed a first thromboembolism and were referred to the Thrombosis Centre: 28 patients (group 1) were prospectively studied, after stopping anticoagulants. Group 1 was compared with a group of 84 patients without an history of renal disease who had suffered from a first thrombotic episode and were matched for age, sex, and type of thrombotic event (group 2). During follow-up, 14/28 group 1 patients and 8/84 group 2 patients experienced thrombotic recurrence (P = .0001). Our data outline the high risk of recurrence in renal transplant recipients. Strategies for recurrence prevention are needed taking into account the high bleeding risk of anticoagulants in renal transplant patients.

Adult↗
PubMedDate not supplied

Homocysteine-lowering therapy and carotid intima-media thickness in renal transplant recipients.

The aim of this study was to document, in hyperhomocysteinemic renal transplant recipients, the effect of vitamin supplementation on carotid intima-media thickness (cIMT). Fifty-six hyperhomocysteinemic stable renal transplant recipients were randomly assigned to either vitamin supplementation (group A) or placebo treatment (group B). All patients underwent high-resolution B mode ultrasound to measure IMT of common carotid arteries before and after 6 months of vitamin supplementation. In group A, cIMT significantly decreased after treatment, whereas no significant changes were observed in group B. In conclusion, our results demonstrate a beneficial effect of the treatment of hyperhomocysteinemia by vitamin supplementation on an early sign of atherosclerosis in a group of renal transplant recipients.

Carotid Arteries↗
PubMedDate not supplied

Thrombophilias as risk factors for disorders of pregnancy and fetal damage.

Inherited thrombophilias have been suggested as a possible condition of increased susceptibility to adverse pregnancy outcomes. Although there is no consensus on the association between the factor V Leiden mutation and early (less than 10 weeks) pregnancy loss, the evidence suggests an association between the mutation and second-, and third-trimester fetal loss and severe preeclampsia. At present the relationship between the prothrombin G20210A mutation and inherited thrombophilias and adverse pregnancy outcomes remains controversial. Due to the low prevalence, AT and PC deficiencies have been rarely found as the cause of complicated pregnancy, whereas increased risk for preeclampsia and fetal losses has been found in relation to PS deficiency. Concerning the association between pathological pregnancies and PAI-1 4G/5G deletion/insertion polymorphism, only few controversial data are available. A meta-analysis of ten case-control studies suggested an association between hyperhomocysteinemia, MTHFR C677T mutation and repeated pregnancy losses before 16 weeks. Recently a role for Angiotensin Converting Enzyme I/D polymorphism in obstetrical complications has been suggested.

Female↗
PubMedDate not supplied

Effect of low-dose heparin treatment on fibrinolysis in patients with previous myocardial infarction.

The present study was designed to investigate whether medium-term, low-dose heparin treatment is able to affect the fibrinolytic system. In a randomized cross-over study 10 asymptomatic patients with previous (1-6 years) myocardial infarction underwent two sequential 15-day treatments, respectively, on heparin and on placebo (saline solution), preceded and separated by 10-day wash-out periods. Heparin (as calcium heparin, 12,500 IU in 0.5 ml) and saline (0.5 ml) were subcutaneously administered once a day at 8 a.m. Blood samples for fibrinolysis studies were withdrawn on the first and 15th day of each period immediately before and 4 h after heparin or saline administration before and after 10 min venous occlusion (VO) respectively. Four hours after the first heparin administration tissue plasminogen activator antigen (t-PA ag) levels significantly increased with respect to saline administration (p < 0.01 and p < 0.05, respectively). After 15-day heparin treatment a decrease in euglobulin lysis time (p < 0.05) and an increase in t-PA activity (act) (p < 0.05) and in t-PA ag (p < 0.01) in comparison with placebo were observed before VO. No statistically significant changes in plasminogen activator inhibitor-1 (PAI-1) levels were found. The variations of fibrinolytic system activity induced by heparin treatment were more marked when evaluated after VO. These results indicate that medium-term low-dose heparin treatment increases t-PA ag formation and/or release with consequent t-PA act increase.

Adult↗
PubMedDate not supplied

Clottable to immunological fibrinogen ratio in plasma from control subjects and hyperfibrinogenemic patients.

The measurement of fibrinogen (Fg) plasma levels is one of the more frequently performed tests in clinical practice, usually by clotting assay. However, for the diagnosis of dysfibrinogenemia the use of an immunological assay is necessary to compare total and clottable protein. Little information is available on the range of the ratio clottable (C) Fg/immunological (I) Fg levels in normal population. This study aimed at evaluating the CFg/IFg ratio in 70 control subjects (age range 17-74 years-group A), in 57 acute patients (age range 17-79 years-group B) and in 14 pregnant women (age range 27-41 years, pregnancy weeks 30-40-group C), as a physiologic model of hyperfibrinogenemia. CFg was assayed on citrated plasma by the Clauss clotting method and IFg was assayed by radial immunodiffusion technique. In the three groups, CFg/IFg ratios were not significantly different (respectively group A 0.98 +/- 0.17, group B 1.02 +/- 0.18 and group C 1.01 +/- 0.11), whereas both CFg (310 +/- 45 mg/dl) and IFg (326 +/- 70 mg/dl) levels were lower (p < 0.001) in control subjects than in patients (CFg 556 +/- 92 mg/dl; IFg 561 +/- 121 mg/dl) and in pregnant women (CFg 530 +/- 65 mg/dl; IFg 530 +/- 77 mg/dl). The analysis of the relationship between CFg and IFg in the three groups (group A: y = 11.53 + 1.01x, r = 0.64, p < 0.001; group B: y = 68.72 + 0.88x, r = 0.67, p < 0.0001; group C: y = 71.59 + 0.87x, r = 0.73, p < 0.01) indicates that a good correlation exists (p < 0.001) for values of fibrinogenemia ranging from 180 to over 700 mg/dl. A reference range of CFg/IFg (mean +/- 2 SD in group A) was 0.64-1.32. These data could be of practical importance for a rapid screening of dysfibrinogenemias.

Adolescent↗
PubMedDate not supplied

Hyperhomocysteinemia in renal transplant patients: an independent factor of cardiovascular disease.

Hyperhomocysteinemia (Hcy) is an independent factor of cardiovascular disease, which is the main cause of morbidity and mortality both in uremic and kidney transplant patients. The aim of the study was to determine Hcy, plasminogen activator inhibitor (PAI-1) and lipoprotein (a) (Lp(a)) serum levels in 70 patients with a well functioning renal transplant. We also verified whether these levels were modified by a multivitamin therapy. The genetic polymorphism of the methylenetetrahydrofolate reductase (MTHFR) enzyme which plays a main role in Hcy metabolism, was studied as well. We found Hcy, PAI-1 and Lp(a) levels significantly elevated with respect to healthy control subjects. The thermolabile form of the MTHFR enzyme was linked to higher Hcy levels. After a short time on therapy with B6, B12 and folic acid vitamins, Hcy and PAI-1 decreased to normal levels. The authors conclude that high Hcy levels could be a relevant covariate for cardiovascular disease in transplant patients and they suggest that vitamin supplementation be recommended as a part of therapy.

Cardiovascular Diseases↗
PubMedDate not supplied

The fibrinolytic system components are increased in systemic sclerosis and modulated by Alprostadil (alpha1 ciclodestryn).

OBJECTIVES: To evaluate urokinase plasminogen activator (u-PA), urokinase plasminogen activator soluble receptor (su-PAR), plasminogen activator inhibitor 1 (PAI-1) and tissue plasminogen activator (t-PA) plasma levels in SSc patients (pts) versus healthy controls and their modulation by intravenous alphacyclodestrine (Alprostadil). METHODS: Plasma levels of u-PA, su-PAR, PAI-1 and t-PA were measured in 40 SSc (34 lSSc and 6 dSSc) pts and in 30 healthy controls. In SSc, blood was drawn before and after 3 consecutive daily of Alprostadil infusion (60 mg in 250 cc NaCl 0.9%). RESULTS: In SSc su-PAR basal levels were higher than controls (7.48 +/- 2.5 vs 4.69 +/- 0.4 ng/ml; p = 0.001) and were significantly reduced by Alprostadil (5.93 +/- 1.7; p = 0.002), but remain higher than controls (p = 0.03). u-PA basal levels were higher than controls (3.78 +/- 1.5 vs 1.29 +/- 0.3 ng/ml; p < 0.001) and were reduced by Alprostadil (2.39 +/- 1.7; p < 0.001) to control levels. SSc PAI-1 basal levels were lower than controls (31.60 +/- 7.7 vs 48.30 +/- 6.8 ng/ml; p < 0.001) and increased by Alprostadil (34.66 +/- 5.4; p = 0.04), but lower than controls (p < 0.001). SSc t-PA basal levels were higher in respect to controls (1645.81 +/- 792.7 vs 571.95 +/- 75.5 pg/ml; p < 0.0001) and reduced by Alprostadil (1318.06 +/- 603.5; p = 0.04), but still higher than controls (p = 0.001). CONCLUSION: Fibrinolysis were increased in SSc. Infusions of Alprostadil modulate u-PA, su-PAR, PAI-1 and t-PA, restoring near normal levels. In SSc, fibrinolysis system may become a potential target for new therapies.

Aged↗
PubMedDate not supplied

Etrurians vs Greeks: May ACE I/D polymorphism still be considered as a marker of susceptibility to SSc?

OBJECTIVE: SSc is characterized by immune dysfunction and microvascular involvement. A different genetic background may determine a different polymorphic allele frequency between different populations, and data from literature reported conflicting results about the role of genetic components in predisposing to the disease. We carried out this study in order to compare the ACE I/D polymorphism genotype distribution and alleles frequency in two different populations from the Mediterranean area. METHODS: Forty-eight Italian and 41 Greek SSc patients compared with 112 Italian and 93 Greek controls, have been studied. The ACE I/D polymorphism has been analysed. RESULTS: The genotype distribution and allele frequency were in Hardy-Weinberg equilibrium for Italian and Greek SSc patients and controls. Among the Italian patients a significantly higher ACE D allele frequency than in the controls was found, whereas among the Greeks a higher prevalence was observed in the healthy subjects. A significant difference in ACE D allele frequency between Italian and Greek controls was observed (p = 0.04). ACE D allele was associated to the predisposition to SSc in Italians, but not in Greeks. CONCLUSION: We confirm that Italian SSc patients have a higher ACE D allele frequency that is not present in the Greek patients. Thus, the two populations living in different Mediterranean areas and resulting from the Mediterranean civilization, do not show the same ACE-gene related allele frequencies. Other populations of the Mediterranean area must be investigated by using unlinked genetic markers to verify the homogeneity of the genetic background, and to test for a "true" difference in their ethnic origin.

Amino Acid Substitution↗
PubMedDate not supplied

Human prostacyclin platelet receptors and platelet lipid composition.

To assess the role of the cellular lipid environment in the expression of prostacyclin (PGI2) membrane receptors, PGI2 binding sites together with cholesterol and phospholipid content in platelets from 17 healthy subjects were investigated. Membrane receptors were investigated by a direct radioligand binding method using [3H]PGI2 as radiolabeled ligand. Significant negative correlations between PGI2 high-affinity receptors and platelet cholesterol content (r = -0.787, P less than 0.001) and platelet cholesterol/phospholipid ratio (r = -0.946, P less than 0.001) were observed; on the contrary phospholipid content was positively correlated with the number of high-affinity receptors (r = 0.610, P less than 0.01). These results indicate that physiological changes in platelet lipid composition can affect membrane receptor number.

Adult↗