Biomedical subjects

L Mazzanti

Publications and source records attributed to L Mazzanti.

At least 19 recordsLinked to original sources

PubMed2007

Combined use of WEB2170 and HBO therapy can reduce ischemia and reperfusion injury to the skeletal muscle in a rabbit model.

Ischemia/reperfusion injury is regarded as the main cause of failure in revascularization of limbs and transfer of free flaps in the so called nonreflow phenomenon. This type of damage is caused by the production of free radicals, above all, of neutrophils that release great quantities of extracellular superoxide through the action of a membrane enzyme. In our study we used 40 white rabbits. Rabbit rectus femoris muscle is perfused by a single artery and vein and is therefore a valuable model for study of ischemia-induced reperfusion injury of skeletal muscle. The objective of this study was to individualize a valid method of protection for the muscle from damage by ischemia-induced reperfusion injury. We have tested the effectiveness of WEB2170, a PAF antagonist, of hyperbaric oxygen therapy one (HBO), and of combined employment of WEB2170 and HBO. The results show that both PAF and HBO play important protective roles against damage from ischemia/reperfusion injury, and that the combined employment of both therapies has a synergistic effect. We propose therefore a new therapeutic protocol for the prevention of damage resulting from ischemia/reperfusion injury with the simultaneous employment of this PAF and HBO.

Animals↗

PubMed2006

Homocysteinylation of low-density lipoproteins (LDL) from subjects with Type 1 diabetes: effect on oxidative damage of human endothelial cells.

BACKGROUND: Homocysteine (Hcy) is an independent risk factor for cardiovascular disease (CVD). Individuals with Type 1 and Type 2 diabetes are more susceptible to the effects of homocysteine than non-diabetic subjects. The interaction between homocysteine-thiolactone (Hcy-thiolactone), a reactive product of Hcy, and low-density lipoproteins (LDL) induces the formation of homocystamide-LDL adducts (Hcy-LDL) and it has been suggested that homocysteinylation could increase atherogenicity of lipoproteins. AIM: The aim of the study was to compare the effect of in vitro homocysteinylation of LDL isolated from healthy control subjects (C-LDL) and from Type 1 diabetic patients (DM-LDL) and to investigate the effect of homocysteinylated LDL (Hcy-C-LDL and Hcy-DM-LDL) on peroxynitrite production of endothelial cells. METHODS: The in vitro homocysteinylation of LDL isolated from control (n = 12) and DM subjects (n = 12) was carried out by incubating lipoproteins with Hcy-thiolactone. The reaction was verified by quantifying the increase in sulphydryl groups (-SH groups) in Hcy-LDL with respect to control LDL. Control and homocysteinylated LDL were incubated with human aortic endothelial cells (HAEC) in culture. Peroxynitrite production in cells treated in different experimental conditions was assayed by a fluorimetric method. RESULTS: The increase in -SH groups after incubation with homocysteine was greater in LDL from diabetic subjects compared with LDL from control subjects (P < 0.001). In addition, peroxynitrite production from HAEC incubated with Hcy-LDL from diabetic patients was greater than after incubation with Hcy-LDL from control subjects and untreated LDL from diabetic patients (P < 0.001). CONCLUSIONS: These results show that LDL from diabetic patients is more susceptible to in vitro homocysteinylation than LDL from non-diabetic individuals and demonstrate that the compositional changes in Hcy-LDL from diabetic subjects have cytotoxic effects on human endothelial cells.

Adult↗

PubMed2005

Peroxynitrite production and NOS expression in astrocytes U373MG incubated with lipoproteins from Alzheimer patients.

Apolipoprotein E (apo E), a plasma protein involved both in the metabolism of cholesterol and triglycerides, particularly in nervous tissue, has been associated with a higher risk of Alzheimer's disease. It has been shown that apo E increased the production of nitric oxide (NO) from human monocyte-derived macrophages (MDM); this effect could represent an important link between tissue redox balance and inflammation, since inflammation and oxidative stress are involved in chronic neurodegenerative disorders. Moreover, it has been evidenced that an overproduction of NO in the central nervous system (CNS) may play a key role in aging and that the glial cells (microglials cells and probably astrocytes) are able to form consistent amounts of NO through the induction of a nitric oxide synthase (iNOS) isoform so-called inducible or inflammatory. This report was performed in order to elucidate the effects produced by lipoproteins from control subjects, AD patients and first degree relatives (offspring) on human astrocyte cells after a short incubation. Peroxynitrite and NO production and NOS expression in cultured astrocytes were measured. We observed a decreased NO production after incubation with both LDL and HDL and an increased peroxynitrite production. As it concerns NOS expression, densitometric analysis of bands indicated that iNOS protein levels were significantly higher in the cells incubated with both AD lipoproteins and offspring lipoproteins compared to cells incubated with control lipoproteins. These findings suggest the possibility to identify in NO pathway a precocious marker of AD.

Aged↗

PubMed2005

Final height in a patient with Laron syndrome after long-term therapy with rhlGF-I and short-term therapy with LHRH-analogue and oxandrolone during puberty.

OBJECTIVE: To report our experience on long-term treatment with recombinant-human-IGF-I (rhIGF-I) of a female patient with Laron syndrome (mutation G223G in the GH receptor gene), who received short-term treatment (1 yr) with LHRH analogue at the start of puberty and subsequently with oxandrolone. CASE REPORT: The patient started IGF-I therapy (dose 40 microg/kg bid for 9 months, 80 microg/kg bid until 13.7 yr of age and 120 microg/kg bid thereafter) when she was 7.6 yr old (height -6 sds), and was treated for 9.4 yr until final height (cm 129.7; -5.5 sds). At first signs of puberty (age 12.7 yr; height 116.3; -5.3 sds), LHRH analogue was started (3.75 mg/28 days) and bone age progressed by 6 months in the 12-month period. Growth velocity decreased in the 6-12th month of combined treatment (0.9 cm/6 months), and treatment was suspended. At age 14.8 (height 124.5; -6.6 sds), oxandrolone was added (0.1 mg/kg/day), but after 12 months (height 128 cm; -5.7 sds) bone age increased from 11.5 to 13.5 yr and the drug was stopped. No side effects occurred during the various treatments. Body segments progressed harmonically: there was a tendency towards improvement in the upper to lower body segment ratio and in cranial growth. Only biiliac diameter did not increase during LHRH treatment. During the 9-yr period, body mass index (BMI), subscapular and triceps skinfold centiles did not show any significant variations. CONCLUSIONS: Our patient with Laron syndrome after long-term treatment showed a final result below the initial expectations, confirming that IGF-I used with the present schedule is less effective than GH in GH-deficient patients. LHRH analogue therapy at puberty was associated with a slower bone age maturation but with an almost complete arrest of growth. On the contrary, oxandrolone sustained growth but caused an excessive maturation of bone age. Other strategies are necessary to improve final height in these patients.

Age Determination by Skeleton↗

PubMed2005

Changes of plasma membrane properties in a human pre-T cell line undergoing apoptosis.

A variety of cellular functions are modulated by the physical properties of the cell membrane, and the modification of intracellular transfer, resulting from loss of membrane integrity, may contribute toward setting the cell onto the pathway of apoptosis. Apoptosis in lymphoid cells can be induced in different ways and biochemical modifications occur at an early phase of cell death, while the morphological features of apoptosis are evident later. We previously reported that DMSO is an efficient apoptosis-inducing factor in the human RPMI-8402 pre-T cell line. The aim of the present study was to verify the effect of DMSO on the plasma membrane fluidity, the intracellular calcium concentration and the phosphodiesterase activity in DMSO-induced apoptosis. Our results show a modification of membrane fluidity associated with an increase of intracellular Ca(2+) concentration. Moreover, we demonstrate that these modifications are related to a decrease in the phosphodiesterase (PDE) activity. The correlation between the proceedings of added DMSO and the induction of apoptosis will provide significant information regarding the first part of the apoptotic process.

Apoptosis↗

PubMed2005

Platelet membrane fluidity and peroxynitrite levels in migraine patients during headache-free periods.

Previous investigations have suggested that changes in platelet activity may play a key role in the pathophysiology of migraine via mechanisms involving the nitric oxide (NO) pathway. Changes in platelet response and nitrite levels have recently been demonstrated during migraine attacks, while there is considerable uncertainty about NO activity in headache-free periods. A reactive oxidant produced from NO and superoxide anion at the site of inflammation, peroxynitrite (ONOO-) has effects including changes in membrane activity and fluidity. The aim of the present study was to determine ONOO- levels in the platelets of patients suffering from migraine during the headache-free period. Nitric oxide synthase (eNOS and iNOS) expression in platelets and the effects of ONOO- on membrane Na+/K+-ATPase activity and membrane fluidity were also evaluated. Subjects were 57 patients suffering from migraine without aura and 35 controls. Blood samples were collected in the headache-free period. Platelet ONOO- levels were determined using dichlorofluorescein acetate with steady-state fluorescence. Platelets were then probed for induction of eNOS and iNOS expression by western immunoblotting. Membrane Na+/K+-ATPase activity and fluidity were determined with the fluorescent probes TMA-DPH and DPH. In the presence of extracellular l-arginine(100 micromol/l), ONOO- production was significantly greater in patients' platelets than in those of controls (P < 0.001). Western immunoblotting of platelet proteins evidenced higher iNOS expression in patients than in controls. In addition, platelet membrane Na+/K+-ATPase activity and membrane fluidity evaluated by TMA-DPH were significantly lower in patients (P < 0.001). In conclusion, migraine patients show intercritic changes in platelet membrane fluidity and activity that may be related to the oxidative stress caused by increased ONOO- levels.

Adult↗

PubMed2004

LDL and HDL affect nitric oxide metabolism in human astrocytoma cells.

Astrocytes provide structural, trophic and metabolic support to neurons and modulate synaptic activity. Under physiological conditions, neuronal-derived nitric oxide (NO) plays an important role in the modulation of a variety of central nervous system (CNS) functions. NO, although short lived, can travel sufficient distances to be able to act as an intercellular messenger in the brain. Its targets include adjacent neurons and astrocytes. The aim of the present study was performed in order to investigate the effects produced by incubation of lipoproteins, at different times, with human astrocytoma cells and thus measuring NO and its metabolite production. NO and peroxynitrite production, iNOS and nNOS expression by Western immunoblot were evaluated. The LDL and HDL-treated cells showed an increased production of NO, more evident after 12 h, compared to basal levels; concerning peroxynitrite production, LDL and HDL-treated cells showed a higher fluorescence, more evident at 3 h. nNOS and iNOS protein levels were significantly higher in the cells incubated with control LDL and HDL. The present work supports the hypothesis that lipoproteins can induce the formation of reactive astrocytes, inducing iNOS as reported by other authors, giving experimental support to a role played by LDL and HDL inducing a reactive response.

Aged↗

PubMed2004

Gestational diabetes affects platelet behaviour through modified oxidative radical metabolism.

AIMS: Patients with Type 1 and Type 2 diabetes mellitus show altered platelet function including decreased nitric oxide synthase (NOS) activity and increased peroxynitrite production. Gestational diabetes mellitus (GDM) is a clinical condition which is ideal for evaluating short-term effects of impaired glucose metabolism, ruling out the possibility that the platelet abnormalities are a consequence of diabetic complications. The aim of the present work was to study NO metabolism in platelets from pregnant women with GDM. The production of peroxides was also studied as it is strongly involved in peroxynitrite formation. METHODS: Platelet NOS activity and peroxynitrite production, levels of hydroperoxides and thiobarbituric acid reactive substances (TBARS) in platelet membranes in the basal state and after in vitro peroxidative stress with phenylhydrazine were determined in 40 pregnant women with GDM, 40 healthy pregnant women (pregnant controls) of comparable age and gestational age, and 15 healthy non-pregnant women (controls). RESULTS: NOS activity was significantly increased in both groups of pregnant women compared with non-pregnant ones, and in GDM women compared with pregnant controls. Production of peroxynitrite was higher in GDM women than in pregnant controls, who also had significantly reduced production compared with non-pregnant women. Basal levels of peroxidation of the platelet membranes evaluated either by hydroperoxide content and TBARS levels or the susceptibility to peroxidation were increased in GDM patients in comparison with both control groups. CONCLUSIONS: We have shown a modification in platelet NO and peroxynitrite production and an increase in platelet indicators of oxidative stress in GDM women compared with healthy pregnant women which might be at the basis of a cellular dysfunction.

Adult↗

PubMed2004

Chemical-physical properties of lipoproteins in anorexia nervosa.

BACKGROUND: Anorexia nervosa (AN), a psychosomatic disorder, has serious negative effects on multiple organs and systems of the human body. Anorexia nervosa usually runs a chronic course and is associated with significant morbidity and mortality. In order to elucidate the role played by lipids in AN, in the present study we compared the plasma lipid profile and the chemical-physical properties of lipoproteins obtained from subjects affected by AN. MATERIALS AND METHODS: The study was performed on lipoproteins of AN subjects and of age-matched healthy subjects used as controls. We tested the susceptibility to oxidative stress in vitro, the fatty acid content, the fluidity using 2-dimethylamino-(6-lauroyl)-naphthalene (Laurdan) and 1,6-difenil-1,3,5-esatriene (DPH) probes. RESULTS: Present results indicate that AN patients present a deep alteration of the composition and of chemical-physical properties in circulating lipoproteins, even in the absence of significant modifications to clinical metabolic parameters. A significantly decreased body mass index (BMI) was found in AN patients in comparison with controls. Anorexia nervosa patients showed a significant modification of phospholipids to protein ratio and a significantly increased percentage of unsaturated fatty acids compared with control subjects as well as a decreased fluidity, a significantly increased percentage of liquid-crystalline phase in VLDL, and a significantly reduced susceptibility to oxidative stress, more pronounced in LDL. CONCLUSIONS: These results confirm the hypothesis that anorexia is accompanied by changes of lipid metabolism in the central nervous system (CNS).

Adult↗

PubMed2004

Modification induced by homocysteine and low-density lipoprotein on human aortic endothelial cells: an in vitro study.

The aim of the present study was to investigate the effect exerted by low-density lipoprotein (LDL) modified by homocysteine (Hcy)-thiolactone (Hcy-LDL) on functional properties on human endothelial cells. Hcy-thiolactone, a reactive product formed in human cells from enzymatic conversion of Hcy, was hypothesized to play an important role in Hcy-induced vascular damages. Using endothelial cultured cells [human aortic endothelial cells (HAEC)] as cellular model, we evaluated nitric oxide (NO) production, cytoplasmic Ca(2+) levels, Na(+)/K(+)-ATPase activity, and peroxynitrite production in cells incubated in the presence of control LDL or Hcy-LDL. Homocysteinylation of LDL was carried out by incubation of LDL, isolated from plasma of healthy subjects, with 100 microm Hcy-thiolactone. A significant increase in cytoplasmic Ca(2+) levels and peroxynitrite production and a decrease in Na(+)/K(+)-ATPase and NO production in HAEC incubated with Hcy-LDL compared with HAEC incubated with control LDL were observed. Moreover, a positive correlation was found between Na(+)/K(+)-ATPase activity and cytoplasmic Ca(2+) content and between peroxynitrite activity and cytoplasmic Ca(2+) content. In conclusion, our results demonstrated that LDL homocysteinylated in vitro induced alterations of functional properties and NO metabolism of human endothelial cells.

Adult↗

PubMed2003

Amniotic levels of vascular endothelial growth factor and nitric oxide at the second trimester in Down's syndrome.

OBJECTIVE: Since placentae in trisomy 21 show trophoblastic hypoplasia and hypovascularity, we investigated amniotic fluid vascular endothelial growth factor (VEGF) and nitric oxide (NO) in normal pregnancy and pregnancy complicated by trisomy 21. Furthermore, we investigated a possible role of NO in neurodegeneration of the brain in Down's syndrome. METHODS: We retrospectively assessed NO and VEGF on mid-trimester amniotic fluid from 15 women who had fetal Down's syndrome, and compared the results with those of 15 controls matched for age and gestation. RESULTS: In pregnancies complicated by trisomy 21, NO levels were significantly higher than in healthy controls (p < 0.001), whereas VEGF levels were significantly lower than in healthy controls (p < 0.05). CONCLUSIONS: Our results suggest that the high levels of NO and the low levels of VEGF observed in the amniotic fluid of fetuses with Down's syndrome may be a sign of an imbalance of placental vascularization and altered endothelial function. Overproduction of NO could contribute to pathological cell death in the central nervous system, a process that has been demonstrated in many neurodegenerative diseases.

Adult↗

PubMed2003

Amniotic levels of nitric oxide in women with fetal intrauterine growth restriction.

OBJECTIVE: Many biochemical observations have shown that nitric oxide (NO) is involved in the vascular angiogenic activity of the fetoplacental unit. The aim of this study was to determine whether NO is implicated in the pathogenesis of intrauterine growth restriction (IUGR). METHODS: We retrospectively assessed amniotic fluid NO from second-trimester amniocentesis of 20 healthy normotensive women who subsequently developed IUGR and 20 controls. The same women were re-assessed at the third trimester when IUGR had developed and when the same 20 controls had shown normal pregnancy. Amniotic fluid NO was detected by discontinuous spectrophotometry and the Griess reaction. RESULTS: At the second trimester, NO levels in women with subsequent IUGR were significantly lower than in controls (4.1 +/- 0.2 microg/mg creatinine vs. 6.02 +/- 1.57 microg/mg creatinine, p < 0.001). At the third trimester, in women with IUGR, NO levels were significantly higher than in normal pregnancies (7.4 +/- 1.5 vs. 5.02 +/- 0.9 microg/mg creatinine, p < 0.001), and directly correlated with gestational age when growth restriction was diagnosed (r = 0.69, p < 0.001). CONCLUSIONS: Low levels of NO during the early second trimester may represent an impaired stimulus to vascular formation and endothelial regulation, inducing placental disease and subsequent fetal growth restriction. High levels of amniotic fluid NO during the third trimester may represent a compensation factor for maintaining adequate uteroplacental perfusion in pregnancies with IUGR.

Amniotic Fluid↗

PubMed2003

Gonadal function and pubertal development after treatment of a childhood malignancy.

As survival rates for childhood cancer have improved, the importance of assessing gonadal dysfunction caused by alkylating agents and radiotherapy in children treated for cancer has increased. Infertility is the major long-term side effect of chemotherapy (CT) in males, whereas Leydig cell function is less affected. Our studies confirm that prepuberty does not protect the male gonad from the late effects of CT and that protocols less gonadal-lesive (such as ABVD regimens) should be preferred. Ovaries are less affected, but early depletion of follicles and premature menopause may occur. High-dose busulfan conditioning regimens cause ovarian failure in young females. The role of gonadal irradiation is discussed: high dosages (>2000 cGy) provoke sterility, impaired testosterone secretion in males and estradiol release in females. High dosage hypothalamic-pituitary irradiation causes delayed puberty and hypogonadism in males and females, whereas lower dosages may be associated with early puberty, particularly in females.

Antineoplastic Agents↗

PubMed2002

Reduced susceptibility to peroxidation of erythrocyte plasma membranes from centenarians.

The plasma membrane composition affects intracellular processes and the cellular susceptibility to free radical attack, which has been associated with the impairment of cellular functions occurring during senescence. The study of the modifications of the plasma membrane in centenarians might elucidate the biological mechanisms at the basis of longevity and successful aging. The work was performed in 190 subjects, divided into five groups according to the age range: (1) 21-40 years (n=25); (2) 41-60 years (n=30); (3) 61-80 years (n=30); (4) 81-99 years (n=50); and (5) centenarians (> or = 100 years) (n=55). The following determinations were performed on erythrocyte membranes: (i) the lipid peroxide level (Lp) evaluated as malondialdehyde content; (ii) susceptibility to in vitro oxidation evaluated as difference in the content of thiobarbituric acid-reactive substances before and after phenylhydrazine addition; (iii) unsaturated/saturated fatty acid ratio and individual polyunsaturated fatty acid composition measured by gas chromatography; and (iv) fluidity studied by means of the anisotropy of the probe 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH). Erythrocyte membranes from centenarians showed: (i) decreased basal lipid peroxide levels and reduced susceptibility to peroxidation in comparison with elderly subjects; (ii) increased unsaturated/saturated fatty acid ratio in comparison with every other age group; (iii) higher levels of eicosapentaenoic and docosahexaenoic acid and reduced content of linoleic and arachidonic acid in comparison with elderly subjects; and (iv) decreased anisotropy of TMA-DPH, i.e. higher fluidity compared with all the other age groups. In conclusion, the present work demonstrates that erythrocyte membranes from centenarians show some distinct features in comparison with elderly subjects that might act in a protective way against injuries.

Adult↗

PubMed2002

Sialic acid content in erythrocyte membranes from pregnant women affected by gestational diabetes.

Sialic acid (SA) content, membrane fluidity, and Na(+)/K(+)-adenosine triphosphatase (ATPase) activity were determined in erythrocyte membrane from 10 nonpregnant women (HNPW), 16 pregnant women affected by gestational diabetes mellitus (GDM), and 25 healthy pregnant women (HPW). In GDM patients the membrane erythrocyte SA content was significantly increased compared with HNPW and membrane fluidity was significantly increased in comparison with HPW. Erythrocyte membrane Na(+)/K(+)-ATPase activity was significantly reduced in GDM patients compared both to HNPW and to HPW subjects. A significant inverse correlation was found between 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) anisotropy and erythrocyte membrane SA content in HNPW and in HPW, while this significant correlation was not observed in GDM. The present results indicate that in comparison with normal pregnancy GDM is characterized by deep alterations of the erythrocyte plasma membrane physicochemical properties (increased fluidity) and functional activities (reduced Na(+)/K(+)-ATPase activity). These modifications might be at the basis of the altered blood viscosity and placental perfusion observed under such conditions. Moreover, these results show that in physiological pregnancy and in the nonpregnant state, the erythrocyte surface membrane fluidity is inversely correlated with SA content, while in GDM there is an unbalance of this relation, which might be associated with the microcirculatory abnormality present in this disease.

Adult↗

PubMed2002

Glycated low density lipoproteins modify platelet properties: a compositional and functional study.

The interaction between low density lipoproteins (LDL) and platelets might play a central role in the development of atherosclerosis in diabetes. The aim of the present study was to investigate whether the glycation of LDL is associated with modifications of their physico-chemical and functional properties and to study the action of glycated LDL (glycLDL) on platelets. LDL and platelets were isolated from 15 healthy subjects. The content of thiobarbituric acid-reactive substances and the generalized polarization of the fluorescent probe Laurdan were determined in LDL glycated in vitro. Platelets were incubated with native LDL, GlycLDL, and minimally oxidized LDL, and the following parameters were evaluated: platelet aggregation, nitric oxide production, intracellular Ca(2+) concentrations, Na(+)/K(+)-adenosine triphosphatase (Na(+)/K(+)-ATPase), and Ca(2+)-ATPase activities. GlycLDL showed increased thiobarbituric acid-reactive substance levels, a red shift of the Laurdan emission maximum, and a decrease in generalized polarization, indicating a higher polarity and a reduced molecular order compared with native LDL. GlycLDL caused a significant increase in platelet nitric oxide production, intracellular Ca(2+) concentration, and aggregating response to ADP; an inhibition of the platelet membrane Na(+)/K(+)-ATPase activity; and a stimulation of Ca(2+)-ATPase activity. Minimally oxidized LDL did not cause statistically significant changes in the parameters studied. The present work demonstrates that glycation induces compositional and structural changes in LDL and suggests that an altered interaction between glycLDL and platelets might play a role in the vascular complications of diabetes.

2-Naphthylamine↗

PubMed2001

Homocysteine-induced inhibition of nitric oxide production in platelets: a study on healthy and diabetic subjects.

AIMS/HYPOTHESIS: The molecular mechanisms involved in the platelet activation observed in hyperhomocysteinemia are not known. We aimed to discover if homocysteine concentrations are associated with abnormal platelet nitric oxide production in healthy and diabetic subjects. METHODS: The study cohort included 28 patients with Type I (insulin-dependent) diabetes mellitus, 30 patients with Type II (non-insulin-dependent) diabetes mellitus, and 34 healthy subjects. Homocysteine plasma concentrations were measured by high-performance liquid chromatography. Platelet nitric oxide production was measured using a nitric oxide meter before and after a 3-h incubation with 100 micromol/l homocysteine. Stimulation experiments were done in vitro by the addition of alpha-thrombin (0.2 U/ml). RESULTS: Basal platelet nitric oxide production was lower in diabetic patients than in healthy subjects. Nitric oxide release was reduced by in vitro homocysteine incubation, being lower in platelets from diabetic patients than in platelets from control subjects. Thrombin increased nitric oxide synthesis in platelets from healthy subjects both in the presence and absence of homocysteine. In diabetic subjects thrombin increased nitric oxide release in the absence of homocysteine. But in the presence of homocysteine the response was reduced. An inverse relation was found between plasma homocysteine levels and basal platelet nitric oxide release in diabetic and healthy subjects. CONCLUSION/INTERPRETATION: Homocysteine could exert its atherogenic action in healthy and diabetic subjects partly by inhibiting platelet nitric oxide production with the subsequent increased platelet activation and aggregation.

Adult↗

PubMed2001

Decreased nitric oxide levels and increased calcium content in platelets of hypertensive patients.

Decreased levels of nitric oxide (NO) may contribute to impaired endothelium-dependent vasodilatation in essential hypertension. Moreover, in hypertension, major platelets aggregation and endothelial adhesion, and increased atherogenetic risks are also present. Nitric oxide produced by platelet NO synthase, which is similar to endothelial NO synthase, inhibits platelets aggregation by increasing cytoplasmic cyclic GMP levels and contributes in a major way to the antithrombogenic properties of endothelium. The aim of this study was to investigate platelet NO production and cytosolic Ca2+ levels in patients with essential hypertension and in healthy subjects. We studied NO production in 36 subjects (21 patients had essential hypertension and 15 subjects were normotensive); NO synthase activity was evaluated by measuring nitrite levels by the Griess reaction in the supernatant of sonicated platelets. Cytosolic Ca2+ levels were measured in intact platelets using the fluorescent probe Fura 2-AM. Nitric oxide levels in platelets were found higher in normotensive than in hypertensive patients (P < .0001). Nitric oxide levels in hypertensive women were significantly higher than in hypertensive men (P < .001). Hypertensive women and men had lower levels of nitrite than normotensive women and men (P < .001 and P < .002, respectively). Platelet cytosolic Ca2+ levels were higher in hypertensive patients than in normotensive subjects (P < .001). An inverse correlation was found between platelet cytosolic Ca2+ and NO levels (r = 0.74, P < .002). These data confirm the link between hypertension and altered platelets function and suggest a role for NO in cardiovascular events. Moreover, the higher levels of nitric oxide in child-bearing age women than in men further support the protective effect of estrogens on cardiovascular diseases.

Adult↗