The Effect of Two Low Doses of Aspirin on Whole Blood Thromboxane and Prostacyclin Generation in Healthy Subjects

The effects of two low doses of aspirin (20 mg and 100 mg) on prostacyclin and thromboxane formation during whole blood clotting were studied in 8 healthy volunteers.

A single 100 mg aspirin dose caused more than 90% reduction of both serum TXB2 and 6-keto-PGF1α; a single 20 mg dose of aspirin inhibited serum TXB2 more than 6-keto-PGF1α but effects on these two products could not be completely dissociated.

However, the effect of a single 20 mg aspirin dose on serum TXB2, was of much longer duration than its inhibitory effect on PGI2 synthesis during whole blood clotting.

Platelet Sensitivity to Prostacyclin and Thromboxane Production in Hyperlipidemic Patients

In 13 type II hyperlipidemics (10 males and 3 females; mean age 50.2 ± 10.6 years), in 10 type IV hyperlipidemics (7 males and 3 females; mean age 51 ± 13.3 years) and in 23 healthy age-and sex-matched controls, the following parameters were measured: plasma cholesterol; plasma TG; plasma C-HDL; VLDL, separated in a preparative ultracentrifuge; C-LDL; Apo B, with immunoelectrophoretic method; platelet sensitivity to prostacyclin; TXB2 formation in PRP; TXB2 in serum.

This study provides evidence for: 1. Reduced platelet sensitivity to prostacyclin, more evident in type II hyperlipidemia that provides an additional mechanism involved in increased platelet aggregation found in type II hyperlipidemia.

2. Enhanced TXB2 formation in PRP after thrombin stimulation (664.65 ± 142.18 pmol/108 platelets) only in type II hyperlipidemics and such enhanced formation was positively correlated to C-LDL (r = 0.53; p <0.05) and to Apo B (r = 0.62; p <0.05); serum TXB2 formation rate was also increased in type II hyperlipidemia.

Lipoprotein-associated phospholipase A₂ activity is increased in patients with definite familial hypercholesterolemia compared with other forms of hypercholesterolemia

BACKGROUND AND AIM

Lipoprotein-associated phospholipase A₂ (Lp-PLA₂) plays a key role in atherosclerosis development. It is considered a marker of increased risk of cardiovascular disease (CVD) and plaque vulnerability. Familial hypercholesterolemia (FH) is a genetic disorder characterized by elevated plasma levels of low-density lipoprotein cholesterol and a higher prevalence of early CVD. Our aim was to evaluate the differences in Lp-PLA₂ activity in a population of hypercholesterolemic patients with and without definite FH.

METHODS AND RESULTS

Hypercholesterolemic patients were consecutively recruited. Definite FH was defined according to Dutch Lipid Clinic Network criteria ≥8. All patients underwent routine clinical examination and biological assessments and Lp-PLA₂ activity was measured in blood samples. Among 469 patients, 118 had a definite diagnosis of FH. Lp-PLA₂ activity was significantly higher in definite FH patients compared to non-definite FH patients (206.5 ± 54.5 vs. 180.8 ± 48.4 nmol/min/mL, p < 0.0001). Lp-PLA₂ positively correlated with total cholesterol, LDL-C and apolipoprotein B and negatively with HDL-C and apolipoprotein A-1. In multivariate analysis, definite FH diagnosis, LDL-C, HDL-C and statin treatment remained correlates of Lp-PLA₂ independently of systolic blood pressure.

CONCLUSIONS

Lp-PLA₂ activity was higher in definite FH than in non-definite FH patients independently of LDL-C levels and statin treatment. These results highlight the particular phenotype of FH subjects among hypercholesterolemic patients. As increased Lp-PLA₂ activity suggests, FH patients exhibit higher arterial inflammation that may contribute to their high cardiovascular risk. Our results reinforce the potential beneficial role of statins pleiotropic effects and the need for proper identification and treatment of FH patients.

Retinal arteriolar remodeling evaluated with adaptive optics camera: Relationship with blood pressure levels

AIM

To research a retinal arterioles wall-to-lumen ratio or lumen diameter cut-off that would discriminate hypertensive from normal subjects using adaptive optics camera.

PATIENTS AND METHODS

One thousand and five hundred subjects were consecutively recruited and Adaptive Optics Camera rtx1™ (Imagine-Eyes, Orsay, France) was used to measure wall thickness, internal diameter, to calculate wall-to-lumen ratio (WLR) and wall cross-sectional area of retinal arterioles. Sitting office blood pressure was measured once, just before retinal measurements and office blood pressure was defined as systolic blood pressure>=140mmHg and diastolic blood pressure>=90mmHg. ROC curves were constructed to determine cut-off values for retinal parameters to diagnose office hypertension. In another population of 276 subjects office BP, retinal arterioles evaluation and home blood pressure monitoring were obtained. The applicability of retinal WLR or diameter cut-off values were compared in patients with controlled, masked, white-coat and sustained hypertension.

RESULTS

In 1500 patients, a WLR>0.31 discriminated office hypertensive subjects with a 0.57 sensitivity and 0.71 specificity. Lumen diameter<78.2μm discriminated office hypertension with a 0.73 sensitivity and a 0.52 specificity. In the other 276 patients, WLR was higher in sustained hypertension vs normotensive patients (0.330±0.06 vs 0.292±0.05; P<0.001) and diameter was narrower in masked hypertensive vs normotensive subjects (73.0±11.2 vs 78.5±11.6μm; P<0.005).

CONCLUSION

A WLR higher than 0.31 is in favour of office arterial hypertension; a diameter under<78μm may indicate a masked hypertension. Retinal arterioles analysis through adaptive optics camera may help the diagnosis of arterial hypertension, in particular in case of masked hypertension.

Influence of a new bicycle crank design on aerobic parameters of non-cyclists

AIM

A well known problem in conventional cycling crank systems is the pedalling dead spot when the crank arms are in vertical position. The pedalling dead spot mitigates the power output during the propulsion phase of pedalling. The aim of this study was to verify the effects of a new design of crank system on aerobic parameters of performance in healthy non-cyclists. The mechanical concept of the new system is based on the theory that crank arms should never be perpendicularly aligned to the ground at dead spot.

METHODS

The maximal aerobic capacity (VO2 max) and different parameters of cycling efficiency were measured in 14 (mean±SD of age: 26±5) non-obese (body mass index: 26.0±3.0 kg/m2) healthy men in two different occasions at intervals of 2 days using alternately and in randomized order both the traditional crank system and the system without dead spot respectively.

RESULTS

The workload performed was significantly higher with the new crank system as suggested by the higher exercise duration (12.89 ±2.36 vs. 13.33±2.30 min; P=0.032).

CONCLUSION

The favourable results obtained in this study using the new chainring may be in consequence of a more efficient biomechanics of pedalling that does not reflect changes in O2 consumption and CO2 produced. However, it is not possible to exclude that involuntary motivational factors may have induced the difference in the time test since it was not possible to blind subjects about the two crank systems. Further investigations are necessary to confirm the results of this exploratory study and give a more exhaustive explanation about the mechanisms that allow the possible better performance with this new chainring system.

Glycaemic variability using continuous glucose monitoring and endothelial function in the metabolic syndrome and in Type 2 diabetes

AIMS

Subjects who are at increased risk of developing diabetes may have increased glycaemic variability associated with endothelial dysfunction and possibly subclinical atherosclerosis, which may lead to increased cardiovascular risk observed at the time of diabetes diagnosis. To investigate this hypothesis, we measured endothelial function, carotid intima-media thickness and glycaemic variability using 48-h continuous subcutaneous glucose monitoring in 3 groups of overweight or obese subjects--those without the metabolic syndrome, and those with the metabolic syndrome with or without newly diagnosed Type 2 diabetes.

METHODS

Consecutive subjects, aged 30-65 years with a body mass index >or= 25 kg/m(2) were recruited. Patients were classified as with or without the metabolic syndrome,or as metabolic syndrome with newly diagnosed Type 2 DM. Glycaemic variability was calculated in terms of the coefficient of variation. Endothelial function was measured using brachial artery flow-mediated dilation.

RESULTS

We identified 75 subjects. Mean flow mediated dilation decreased (P < 0.001) and carotid intima-media thickness increased (P < 0.05) across groups. Flow mediated dilation predictors included mean 48-h continuous subcutaneous glucose monitoring values (beta = -0.022; P < 0.005) and the coefficient of variation (beta = -0.10; P = 0.01). Carotid intima-media thickness predictors included age (beta = 0.009; P < 0.001) and flow mediated dilation (beta = -0.014; P = 0.076). Patients re-stratified according to cut-offs for mean 48-h glycaemia and variability demonstrated that subjects with high mean glycaemia but low coefficient of variability had similar flow mediated dilation and carotid intima-media thickness to subjects with low mean glycaemia but high coefficient of variation.

CONCLUSIONS

This study suggests that glycaemic variability influences endothelial function even in non-diabetic subjects. Such variability may explain the increased cardiovascular risk observed in patients prior to developing overt Type 2 diabetes.

A low reported energy intake is associated with metabolic syndrome

BACKGROUND AND AIMS

Metabolic syndrome (MS) may be associated with the presence of an energy-sparing metabolism that predisposes to the excess accumulation of body fat. This study examined the relationship between reported energy intake and obesity in individuals with and without MS.

METHODS AND RESULTS

Ninety consecutive non-diabetic obese subjects were divided into 2 groups based on the presence (MS+: no.=50) or absence (MS-: no.=40) of MS. The study design was cross-sectional. The 3-day food record method was used to assess the subjects' usual energy intake and the Diet Readiness Test (DRT) was also administered. Compared to the MS- group, the MS+ group had a significantly higher body weight, body mass index (mean+/-SEM: 39.1+/-1.3 vs 31.5+/-0.9, p<0.001) and fat mass. The absolute energy intake of the MS+ group (8629+/-331 kJ/24h) did not differ from that of the MS- group (8571+/-515 kJ/24h; p=ns). The daily energy intake normalized for the fat-free mass (FFM) size was higher in the MS- group (163+/-8 kJ/kg-FFM x 24h) than in the MS+ group (138+/-4 kJ/kg-FFM x 24h; p<0.03). The DRT test results were similar in both groups except that section 6 (exercise patterns and attitudes) score was lower in the MS+ group (10.0+/-0.5) than in the MS- group (11.9+/-0.5; p<0.01).

CONCLUSION

The results of this study support the hypothesis that subjects with MS have an energy-sparing metabolism.

Metabolic parameters and adipokine profile during GH replacement therapy in children with GH deficiency

OBJECTIVE

GH replacement therapy in children with GH deficiency (GHD) mainly promotes linear growth. Not only have very few studies fully analyzed the metabolic consequences of GH therapy, but also the question as to whether GH may affect adipokine secretion has been insufficiently investigated. Our aim was to study the effects of GH replacement therapy on auxological data, lipid and glycemic profiles, insulin homeostasis (HOMA-IR) and serum adipokines in children.

METHODS

This was a 1-year prospective study. Thirty-four GHD children (11.6 +/- 2.6 years) and thirty healthy matched controls were enrolled. Children affected by GHD were studied both before beginning continuous GH replacement therapy and again at 12 months.

RESULTS

At the beginning of the study, total and LDL cholesterol were higher in GHD children than in controls (P<0.001), whereas HDL cholesterol, triglycerides, insulin, HOMA-IR, leptin, and adiponectin were similar. At 12 months of continuous GH replacement therapy in the GHD group, there was a significant increase in both auxological data and IGF-I (P<0.001); total cholesterol (P<0.001), LDL (P<0.001), triglycerides (P<0.005), and leptin (P<0.001) decreased significantly; HDL (P<0.003), insulin (P<0.001), HOMA-IR (P<0.001) increased while adiponectin was unmodified. Furthermore, IGF-IDelta showed an inverse correlation with leptin Delta (rho = -0.398, P = 0.02).

CONCLUSIONS

In GHD children, the evaluation of metabolic parameters proves to be a useful tool for the evaluation of auxological parameters during GH replacement therapy. In our study, GH replacement therapy in GHD children improved final height, restored IGF-I levels, reduced leptin levels, and improved the lipid profile, without producing any unfavorable effects on glucose metabolism.

Lower insulin sensitivity differentiates hirsute from non-hirsute Sicilian women with polycystic ovary syndrome

OBJECTIVE

It is well known that hyperandrogenism and insulin-resistance with or without compensatory hyperinsulinism are closely associated, but the Rotterdam Consensus has concluded that principally obese women with polycystic ovary syndrome (PCOS) should be evaluated for the metabolic syndrome. Our aim was to study insulin sensitivity in PCOS women with hirsutism regardless of obesity.

METHODS

Clinical characteristics, sex hormones and fasting- and after OGTT-glycemia and insulinemia, homeostatic model of insulin resistance (HOMA IR), and Matsuda index of insulin sensitivity were analyzed in 130 women with PCOS. Hirsutism has been evaluated through the Ferriman-Gallwey (FG) map scoring system.

RESULTS

PCOS women with hirsutism (57.7% of participants) showed significant higher values of total testosterone levels (P = 0.016), free testosterone (P = 0.027), DHEA sulfate (P = 0.017), and Delta4androstenedione (P = 0.018). They had similar body mass index (BMI) (P = 0.073) and were significantly less insulin sensitive (P = 0.002) than those without hirsutism (42.3% of participants). In women with PCOS and hirsutism, there was a significant correlation between FG score and insulin-sensitivity indexes (HOMA IR, rho = 0.33, P = 0.005; Matsuda index, rho = -0.34, P = 0.003) but not with the androgen levels. Moreover, women with hirsutism showed a significantly greater insulin (P = 0.019), C-peptide (P = 0.002), and glucose (P = 0.024) areas under the curve (auc2h).

CONCLUSIONS

Our study suggests that the increased responsiveness of the pilo-sebaceous unit to androgens seems to be influenced by insulin sensitivity and that insulin resistance should be assessed in all hirsute women with PCOS regardless of their BMI, as insulin resistance was found in hirsute women irrespective of whether they were overweight or obese.

CD4(+)IL-13(+) cells in peripheral blood well correlates with the severity of atopic dermatitis in children

BACKGROUND

In atopic dermatitis (AD) a Th1/Th2 imbalance has been reported, and interleukin (IL)-13 seems to play a pivotal role in the inflammatory network. We tried to assess the correlation between the immunological marker CD4(+)IL-13(+) and the clinical phase of extrinsic AD in children.

METHODS

Twenty children with AD were studied. Assessed parameters were: clinical severity (SCORAD index), total serum immunoglobulin E (IgE), blood eosinophil count, and percentage of CD4(+)IFNgamma(+), CD4(+)IL-4(+), CD4(+)IL-13(+) T cells. Determinations were carried out in the acute phase and after clinical remission were achieved. Ten nonatopic-matched children served as controls.

RESULTS

At baseline, AD was mild in 25%, moderate in 50% and severe in 25% of children. In the acute phase a significant relationship between the eosinophil count and the SCORAD index was found (P = 0.0001). Blood CD4(+)IL-4(+) were significantly higher in the AD group (median 17.0, range: 13.7-21.4) than in controls (12.6, 6.4-17.2, P < 0.0001). CD4(+)IL-13(+) cells in the AD group well correlated (P = 0.0007) with SCORAD index. At remission, a significant correlation between SCORAD index and eosinophil count was found (P < 0.03) and the percentage of CD4(+)IL-13(+) cells globally decreased (P < 0.0001), while no difference was found among SCORAD classes.

CONCLUSION

This study confirms the Th2 profile predominance in the peripheral blood of children with AD, and evidences close relationship between the number of CD4(+)IL-13(+) T cells and the disease's severity.

Up-regulation of c-FLIPshort and reduction of activation-induced cell death in T-cells from patients with Type 1 diabetes

AICD of T-cells is an efficient way of removing activated T-lymphocytes. In this study we investigated the molecular basis of AICD upon reactivation in peripheral T-lymphocytes from newly diagnosed T1DM patients and age-matched healthy controls. In an in vitro model system, PHA-stimulated T-cells, upon prolonged culture in IL-2, acquire a sensitive phenotype to Fas-mediated apoptosis. This phenomenon is less pronounced in T1DM T-cells. Moreover, the restimulation of activated T-cells via TCR/CD3 and/or via CD28 inhibits Fas-mediated apoptosis in T1DM in comparison to control T-cells. After Fas triggering, the generation of the active sub-units of caspase-8 is significantly reduced in T1DM T-cells restimulated via TCR/CD3 and/or CD28. In parallel, we found that the amount of c-FLIPshort protein is significantly increased in the DISC only in T1DM T-cells restimulated via TCR/CD3 and via CD28. These data suggest that increased levels of c-FLIPshort may prevent recruitment of pro-caspase-8 in T1DM CD3-treated T-cells and provide new insight into the molecular mechanisms of apoptosis resistance in stimulated T-cells from T1DM patients.

Differential regulation of Fas-mediated apoptosis in both thyrocyte and lymphocyte cellular compartments correlates with opposite phenotypic manifestations of autoimmune thyroid disease

Several mechanisms are probably involved in determining the evolution of autoimmune thyroid disease (AITD) towards either hypothyroidism and the clinical syndrome known as Hashimoto's thyroiditis (HT) or toward hyperthyroidism and the symptoms of Graves' disease (GD). To gain further insight into such mechanisms we performed an exhaustive comparative analysis of the expression of key molecules regulating cell death (Fas, Fas ligand [FasL], Bcl-2) and apoptosis in both thyrocytes and thyroid infiltrating lymphocytes (TILs) from patients with either GD or HT. GD thyrocytes expressed less Fas/FasL than HT thyrocytes, whereas GD TILs had higher levels of Fas/FasL than HT TILs. GD thyrocytes expressed increased levels of the antiapoptotic molecule Bcl-2 compared to the low levels detected in HT thyrocytes. The opposite pattern was observed in GD (low Bcl-2) and HT (high Bcl-2) TILs. The patterns of apoptosis observed were consistent with the regulation of Fas, FasL, and Bcl-2 described above. Our findings suggest that in GD thyroid the regulation of Fas/FasL/Bcl2 favors apoptosis of infiltrating lymphocytes, possibly limiting their autoreactive potential and impairing their ability to mediate tissue damage. Moreover, the reduced levels of Fas/FasL and increased levels of Bcl-2 should favor thyrocyte survival and favor the thyrocyte hypertrophy associated with immunoglobulins stimulating the thyrotropin (TSH) receptor. In contrast, the regulation of Fas/FasL/Bcl2 expression in HT promotes thyrocyte apoptosis, tissue damage, and a gradual reduction in thyrocyte numbers leading to hypothyroidism. These findings help define key molecular mechanisms contributing to the clinical outcome of thyroid autoimmunity.

[Pancreatic harvesting from multiorgan donors for islet transplantation]

The result of human islet isolation procedures to transplant in type I insulin-dependent diabetic patients is significantly conditioned by the technique used for pancreas procurement from multiorgan donor. In fact, during multiorgan procurement, an improper handling of the gland could result in edema or degranulation of the acinar tissue, detrimental for the islet purification step. The surgical technique used by our surgical team, includes some important refinements to obtain the largest quantity and the best quality of purified endocrine material.

[Evaluation of the use of calcitonin in rheumatoid arthritis by bone densitometry and the study of of phospho-calcium metabolism]

Forty-eight patients were subdivided into three groups according to the stage of their rheumatoid arthritis and to whether or not they received glucocorticoids; they were compared to healthy volunteers of similar sex, age, and body weight. Before calcitonin treatment, bone mineral content (BMC) of RA patients was significantly lowered, especially in patients with 3rd and 4th Steinbroker degree and in those taking glucocorticoids. Synthetic eel calcitonin was administered in three 60-day cycles separated by 40-day intervals with daily dosage 40 U.M.R.C. (1 vial). This treatment did not result in a increase of BMC compared to baseline. A further decrease of BMC observed at the end of treatment was not statistically significant. No appreciable variation was found in parameters of phospho-calcic metabolism.

Study of T-cell activation in type I diabetic patients and pre-type I diabetic subjects by cytometric analysis: antigen expression defect in vitro

In Type I diabetes the observation of a decreased release of interleukin-2 (IL-2) and soluble IL-2 receptors by means of stimulated lymphocytes in vitro indicates that a primary immunoregulatory defect may be involved. To confirm this hypothesis we investigated the T-cell activation trend, evaluating the surface expression of IL-2 receptor (CD25), transferrin (CD71), HLA class II (DR), and CD69 phenotypes after in vitro stimulation with phytohemagglutinin (PHA; 1 and 10 micrograms/ml) and concanavalin A (12.5 micrograms/ml) in six newly diagnosed Type I diabetics and six islet cell- and insulin autoantibody-positive first-degree relatives. As controls were studied six long-standing Type I diabetics and six healthy subjects. T-cell cultures from the four groups were performed on the same day and examined at 0, 24, 48, 96, 120, and 144 hr. Cytometric analysis was performed, keeping PBMC gating constant on the basis of physical parameters (scatter and volume). Using both PHA concentrations, a lower level of CD25, CD71, CD69, and DR antigen expression was found in newly diagnosed patients at all observation times with respect to control cultures (P < 0.001). Unexpectedly, pre-Type I diabetic subjects, after 1 microgram/ml of PHA, showed a significantly reduced expression of CD69 (P < 0.001) and CD71 (P < 0.001). The levels remained low, also with high PHA, at the different observation periods, while CD25 expression was found to be reduced in prediabetics only after 1 micrograms/ml of PHA (P < 0.001). The long-standing patients showed a T cell activation trend very close to the latter. Our data show that in Type I diabetes and in the early phases of the disease, the initial activation signal(s) appears to be affected, particularly with one or more subsequent events necessary to initiate the appearance of "activation antigens." This study suggests that the natural history of immunoregulation in pre-Type I and Type I diabetes is characterized by a primary defect in this system, which also persists in patients with long-standing disease.

Analysis of T-lymphocyte subsets after phytohemagglutinin stimulation in normal and type 1 diabetic mothers and their infants

PROBLEM

Our aim was to investigate the immunological status of diabetic pregnancy, which is an overlap of diabetic immunity abnormalities and the immunological modifications normally occurring during pregnancy.

METHOD

We studied lymphocyte subpopulations and lymphokine production, after 96 h of phytohemagglutinin (PHA) stimulation, from normal and Type I diabetic pregnant women at delivery time and from the respective cord blood.

RESULTS

Peripheral blood mononuclear cells (PBMC) from both normal and Type I diabetic mothers showed an increase in CD8+ and a decrease in CD4+ cells compared to the respective cord blood mononuclear cells (CBMC). Moreover, Type I PBMC showed a lower number of "activated" CD3+ DR+ cells and a higher number of CD8+ CD25+ cells with respect to normal women, which may reflect the dysregulatory pattern due to the autoimmune condition. Type I CBMC showed a big increase in the number of CD4+ Leu8+ cells, a cell subpopulation characterized by inhibitory activity. Finally, as regards lymphokine release in culture supernatants, type I diabetes seemed to be associated with an over-production of IL1 and IL6, although the latter increase is less evident in CBMC cultures.

CONCLUSIONS

The present study shows that diabetic pregnancy is associated with major alterations of cell-mediated immunity leading to a state of immunodepression. Moreover, our study suggests that the maternal immunological status influences fetal immunity, as demonstrated by the increase in the number of regulatory cells and by the altered pattern of lymphokine production (IL1 and IL6) by lymphocytes derived from diabetic CBMC. The latter phenomenon perfectly mirrors maternal PBMC characteristics.

In vivo treatment with a monoclonal antibody to interferon-gamma neither affects the survival nor the incidence of lupus-nephritis in the MRL/lpr-lpr mouse

The effects of the in vitro treatment with a mAb (DB-1) that neutralizes mouse IFN-gamma on the development of the SLE-like syndrome in MRL/lpr-lpr (MRL-lpr) mice were studied. The results show that the i.p. administration of 2.6 mg/week of DB-1 from the 12th to the 20th week of age neither affected the survival nor the incidence and severity of lupus nephritis in MRL-lpr mice. This study argues against the pathogenic relevance of IFN-gamma in this experimental model of human SLE.

Serum reactivity against RINm5F purified membrane antigens (ICMA) in newly diagnosed diabetic subjects

A simple and rapid enzyme-linked immunosorbent assay (ELISA) for the detection of islet cell membrane antibodies (ICMA) in the sera of IDDM has been recently established. This new method has been made possible by using affinity purified islet cell membrane antigens from a monoclonal insulin secreting cell line obtained from a transplantable rat insulinoma (RINm5F). One hundred and thirty-three sera of newly diagnosed diabetic patients (duration of symptoms of less than 3 months) were tested, and ICMA positivity was found in 21% of patients. In the same group we found 64% ICA positive subjects, but no correlation has been found between ICA and ICMA. Therefore these two auto-antibodies should be considered as expression of different steps of the autoimmune beta-cell damage. In this light ICMA could represent a very early marker of autoimmune process and it could be useful to recognize, among risk subjects, those who are developing IDDM.

In vitro effects of gallopamil on platelet aggregation and thromboxane generation

The in vitro effects of gallopamil, a highly specific calcium-channel blocker, on platelet function were investigated. Gallopamil caused a dose-dependent inhibition of platelet aggregation. In fact, the drug in concentrations as low as 0.5 microgram/ml inhibited platelet activating factor and epinephrine-induced platelet aggregation. Similarly, the inhibition of adenosine diphosphate and epinephrine-induced thromboxane generation was demonstrated. Since platelet activation and thromboxane release may be related to myocardial ischemia, it is conceivable that some of the antianginal effects of gallopamil may in part be due to platelet inhibitory effects.

Effects of verapamil on platelet aggregation and serum thromboxane synthesis in vitro and in vivo

The aim of this study was to evaluate the in vitro effects of verapamil on platelet aggregation and serum thromboxane formation. We also studied the in vivo effects of verapamil retard on platelet aggregation and serum thromboxane formation. The incubation of verapamil with PRP produced a dose-dependent decrease of in vitro platelet aggregation for all the agents used. Potentiation by verapamil of antiaggregating activity of prostacyclin was also demonstrated; in fact when verapamil and prostacyclin were added simultaneously a synergistic inhibition of platelet aggregation by ADP was observed. In whole blood verapamil partially inhibited thromboxane production only at a higher concentration. In vivo verapamil significantly decreased platelet aggregation induced by ADP and epinephrine while no changes were observed after arachidonic acid. No significant changes occurred in serum TXB2 levels. The observations suggest a potential role for verapamil in antithrombotic therapy as an antiplatelet agent.

The effect of two low doses of aspirin on whole blood thromboxane and prostacyclin generation in healthy subjects

The effects of two low doses of aspirin (20 mg and 100 mg) on prostacyclin and thromboxane formation during whole blood clotting were studied in 8 healthy volunteers. A single 100 mg aspirin dose caused more than 90% reduction of both serum TXB2 and 6-keto-PGF1 alpha; a single 20 mg dose of aspirin inhibited serum TXB2 more than 6-keto-PGF1 alpha but effects on these two products could not be completely dissociated. However, the effect of a single 20 mg aspirin dose on serum TXB2, was of much longer duration than its inhibitory effect on PGI2 synthesis during whole blood clotting.

Platelet thromboxane formation and BTG levels after intensive charcoal HP in uremics or regular hemodialytic treatment (RHT)

Vascular tissues from uremic patients show increased prostaglandin synthesizing capacity while uremic platelets have decreased thromboxane synthesis. It has been suggested that the platelet defects in uremia are partially corrected by hemodialysis and a correlation with the levels of guanidinsuccinic acid, phenolic acid, creatinine or urea has been demonstrated. In our study 6 patients with end-stage renal disease on RHT, underwent, daily and for ten days, two-hours hemoperfusion, in order to obtain lower levels of toxic metabolites such as creatinine (less than 6 mg/dl.). Before and after this intensive treatment we have evaluated BTG plasmatic levels and thromboxane formation by platelets after thrombin and arachidonic acid stimulation. The thromboxane formation was not increased following this treatment, whereas BTG plasmatic levels were significantly diminished.

Platelet activation after adrenergic stimulation in hypertensive patients: effects of acebutolol

In 12 patients with arterial hypertension (stages I and II according to WHO), adrenergic stimulation was induced by the immersion of a hand in ice water for 2 min. Blood samples were withdrawn before, at the end of, and 15 min after the cold application: the experiment was repeated 2 h after the ingestion of 200 mg acebutolol, a selective betablocking agent. The following assays were performed: serum nonesterified fatty acid (NEFA), plasma beta-thromboglobulin (BTG) and PF4 with specific radioimmunoassays; thromboxane B2 (TXB2) in plasma was also estimated with radioimmunoassay, platelet sensitivity to exogenous prostacyclin; furthermore, the thrombin-induced thromboxane production before and after acebutolol ingestion as well as serum TXB2-levels were measured. The blood pressure and the heart rate were also monitored. After cold stimulation, a significant increase of NEFA, BTG, and plasma TXB2 was observed, which was still discernible 15 min after the application of cold. After acebutolol, the cold treatment led to a lower increase of blood pressure with a reduction of the heart rate, as well as to a diminished release of BTG, PF4 and TXB2 no changes in the reduced platelet sensitivity to prostacyclin were noticed.

Platelet sensitivity to prostacyclin and thromboxane production in hyperlipidemic patients

In 13 type II hyperlipidemics (10 males and 3 females; mean age 50.2 +/- 10.6 years), in 10 type IV hyperlipidemics (7 males and 3 females; mean age 51 +/- 13.3 years) and in 23 healthy age- and sex-matched controls, the following parameters were measured: plasma cholesterol; plasma TG; plasma C-HDL; VLDL, separated in a preparative ultracentrifuge; C-LDL; Apo B, with immunoelectrophoretic method; platelet sensitivity to prostacyclin; TXB2 formation in PRP; TXB2 in serum. This study provides evidence for: 1. Reduced platelet sensitivity to prostacyclin, more evident in type II hyperlipidemia that provides an additional mechanism involved in increased platelet aggregation found in type II hyperlipidemia. 2. Enhanced TXB2 formation in PRP after thrombin stimulation (664.65 +/- 142.18 pmol/10(8) platelets) only in type II hyperlipidemics and such enhanced formation was positively correlated to C-LDL (r = 0.53; p less than 0.05) and to Apo B (r = 0.62; p less than 0.05); serum TXB2 formation rate was also increased in type II hyperlipidemia.

Enhanced platelet release reaction in insulin-dependent and insulin-independent diabetic patients

Plasma beta thromboglobulin (BTG) and platelet factor 4 (PF4) levels were measured and correlated with plasma lipid and lipoprotein patterns in 20 insulin-independent diabetics, in 10 insulin-dependent diabetics and in 30 healthy controls matched to patients as to age, sex and weight. Increased plasma BTG and PF4 levels both in insulin-dependent and in insulin-independent diabetics indicate enhanced in vivo platelet activation and release reaction in these patients. No difference in BTG and PF4 values between these two groups of diabetic patients was observed in our study. A marked correlation between plasma PF4 values and plasma glucose levels was shown in insulin-dependent diabetics only whereas a significant positive correlation with plasma triglycerides and plasma triglyceride VLDL and a negative correlation with cholesterol-HDL was shown in insulin-independent diabetics.