RESUMEN
A series of multicomponent glasses containing up to five oxides are studied using classical molecular dynamics simulations and neutron scattering experiments. The focus is on the role of magnesium in determining the structural properties of these glasses and the possible mixed effect during a sodium/magnesium substitution. Calculated structure functions (pair correlation function and structure factor) rather accurately reproduce their experimental counterpart, and we show that more fine structural features are qualitatively reproduced well, despite some discrepancies in the preferential spatial distribution between sodium and magnesium to aluminum and boron, as well as the nonbridging oxygen, distribution. The simulated systems offer a solid basis to support previous experimental findings on the composition-structure relationship, allowing for further analysis and property calculation. It is confirmed that the substitution of sodium by magnesium leads to the decrease of four-fold boron and a modification of the alkali coordinations with a significant change of the network structure. Specifically, magnesium coordination extracted from numerical simulations highlights a potential dissociation from penta- to tetra- and hexahedral units with increasing MgO contents along the glass series, which could not be resolved experimentally.
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In amyotrophic lateral sclerosis (ALS), motor neuron degeneration occurs simultaneously with systemic metabolic dysfunction and neuro-inflammation. The fibroblast growth factor 21 (FGF21) plays an important role in the regulation of both phenomena and is a major hormone of energetic homeostasis. In this study, we aimed to determine the relevance of FGF21 pathway stimulation in a male mouse model of ALS (mutated SOD1-G93A mice) by using a pharmacological agonist of FGF21, R1Mab1. Mice (SOD1-WT and mutant SOD1-G93A) were treated with R1Mab1 or vehicle. Longitudinal data about clinical status (motor function, body weight) and biological parameters (including hormonal, immunological, and metabolomics profiles) were collected from the first symptoms to euthanasia at week 20. Multivariate models were performed to identify the main parameters associated with R1Mab1 treatment and to link them with clinical status, and metabolic pathways involving the discriminant metabolites were also determined. A beneficial clinical effect of R1Mab1 was revealed on slow rotarod (p = 0.032), despite a significant decrease in body weight of ALS mice (p < 0.001). We observed a decrease in serum TNF-α, MCP-1, and insulin levels (p = 0.0059, p = 0.003, and p = 0.01, respectively). At 16 weeks, metabolomics analyses revealed a clear discrimination (CV-ANOVA = 0.0086) according to the treatment and the most discriminant pathways, including sphingolipid metabolism, butanoate metabolism, pantothenate and CoA biosynthesis, and the metabolism of amino acids like tyrosine, arginine, proline, glycine, serine, alanine, aspartate, and glutamate. Mice treated with R1Mab1 had mildly higher performance on slow rotarod despite a decrease on body weight and could be linked with the anti-inflammatory effect of R1Mab1. These results indicate that FGF21 pathway is an interesting target in ALS, with a slight improvement in motor function combined with metabolic and anti-inflammatory effects.
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Esclerosis Amiotrófica Lateral/metabolismo , Factores de Crecimiento de Fibroblastos/metabolismo , Esclerosis Amiotrófica Lateral/tratamiento farmacológico , Animales , Anticuerpos Monoclonales/uso terapéutico , Quimiocina CCL2/sangre , Modelos Animales de Enfermedad , Factores de Crecimiento de Fibroblastos/inmunología , Factores de Crecimiento de Fibroblastos/fisiología , Interleucina-6/sangre , Leptina/sangre , Masculino , Metabolómica , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Resistina/sangre , Prueba de Desempeño de Rotación con Aceleración Constante , Transducción de Señal , Transcriptoma , Factor de Necrosis Tumoral alfa/sangreRESUMEN
BACKGROUND: Options in second-line therapy after doxorubicin-based chemotherapy for metastatic/advanced leiomyosarcoma include gemcitabine (G), trabectedin and pazopanib (P) monotherapy. Currently, no combination therapy is better than monotherapy. LMS03 is an open-label multicentre single-group phase II study designed to assess the efficacy and tolerance of G + P in the second-line setting. PATIENTS AND METHODS: Patients (pts), ECOG ≤2, with metastatic leiomyosarcomas (LMS) after first-line doxorubicin chemotherapy failure were eligible. Pts were treated with G 1000 mg/m2 on days 1 and 8 of each 21 days (maximum eight cycles), in combination with oral daily P (800 mg), until disease progression/toxicity. 9-month progression-free survival (PFS) rate was the primary endpoint. Inacceptable and promising 9-month PFS rates were defined, in the intent-to-treat population, as 32% and 44%. RESULTS: 106 pts were included with a mean age of 59.8 years and an ECOG 0 in 63.5%; the primary tumour site was uterus in 61%. Pts were treated with P + G for a median of 3.8 mo, and P for a median of 4.2 mo. The 9-month PFS rate was 32.1% (95% CI 23.1-41.1). After a median follow-up of 14.2 months, the PFS was 6.5 months (95% CI 5.6-8.2), and the overall survival was 22.4 months (95% CI 16.9-26.5). The best response was 23.8%. The most frequent reported grade 3-4 adverse events were haematological. CONCLUSIONS: LMS03 failed to show that second-line therapy, with gemcitabine combined with pazopanib, followed by pazopanib alone, was beneficial for advanced LMS patients. Eudract N°2011-001308-36 and NCT01442662.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Desoxicitidina/análogos & derivados , Leiomiosarcoma/tratamiento farmacológico , Pirimidinas/uso terapéutico , Sulfonamidas/uso terapéutico , Adulto , Anciano , Anciano de 80 o más Años , Antimetabolitos Antineoplásicos , Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Desoxicitidina/farmacología , Desoxicitidina/uso terapéutico , Femenino , Humanos , Indazoles , Masculino , Persona de Mediana Edad , Pirimidinas/farmacología , Sulfonamidas/farmacología , GemcitabinaRESUMEN
INTRODUCTION: Converging evidence highlights that lipid metabolism plays a key role in ALS pathophysiology. Dyslipidemia has been described in ALS patients and may be protective but peripheral lipoprotein subclasses have never been studied. MATERIAL AND METHODS: We collected sera from 30 ALS patients and 30 gender and age-matched controls. We analyzed 11 distinct lipoprotein subclasses by linear polyacrylamide gel electrophoresis (Lipoprint, Quantimetrix Corporation, USA). We also measured lipoprotein (a), apolipoprotein B, and apolipoprotein E levels. RESULTS: ALS patients had significant higher total cholesterol, HDL-cholesterol, and LDL-cholesterol levels than controls (p<0.0001, p=0.0007, and p=0.0065, respectively). The LDL-1 subfraction concentration was higher (1.03±0.41 vs. 0.71±0.28mmol/L; p=0.0006) and the IDL-B subfraction lower (6.5±2% vs. 8.0±2%; p=0.001) in ALS patients than controls. DISCUSSION: Our preliminary work confirmed the association between ALS and dyslipidemia. The low IDL-B levels may explain the hepatic steatosis frequently reported in ALS. The high levels of the cholesterol-rich LDL-1 subfraction is consistent with previously reported hypercholesterolemia. CONCLUSION: This study describes, for the first time, the distribution of serum lipoproteins in ALS patients, with low IDL-B and high LDL-1 subfraction level.
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Esclerosis Amiotrófica Lateral/sangre , Lipoproteínas IDL/sangre , Lipoproteínas LDL/sangre , Anciano , Biomarcadores/sangre , Estudios de Cohortes , Dislipidemias/sangre , Femenino , Humanos , Lipoproteínas HDL/sangre , Masculino , Datos PreliminaresRESUMEN
We have carried out classical molecular dynamics simulations in order to get insight into the atomistic mechanisms of the deformation during nanoindentation of the pristine and irradiated forms of a sodium borosilicate glass. In terms of the glass hardness, we have found that the primary factor affecting the decrease of hardness after irradiation is depolymerization rather than free volume, and we argue that this is a general trend applicable to other borosilicate glasses with similar compositions. We have analyzed the changes of the short- and medium-range structures under deformation and found that the creation of oxygen triclusters is an important mechanism in order to describe the deformation of highly polymerized borosilicate glasses and is essential in the understanding of the folding of large rings under stress. We have equally found that the less polymerized glasses present a higher amount of relative densification, while the analysis of bond-breaking during the nanoindentation has showed that shear flow is more likely to appear around sodium atoms. The results provided in this study can be proven to be useful in the interpretation of experimental results.
RESUMEN
We have performed classical molecular dynamics simulations in order to study the changes under compression in the local and medium range structural properties of three sodium borosilicate glasses with varying sodium content. These glasses have been isostatically compressed up to 20 GPa and then decompressed in order to analyze the different mechanisms that affect densification, alongside with the permanent modifications of the structure after a full compression/decompression cycle. The results show that the atomic packing is the prominent characteristic that governs the amount of densification in the glass, as well as the setup of the permanent densification. During compression, the bulk modulus increases linearly up to approximately 15 GPa and more rapidly for higher pressures, a behavior which is reflected on the rate of increase of the average coordination for B and Na. Radial distribution functions at different pressures during the cycle help to quantify the amount of distortions in the elementary structural units, with a pronounced shortening of the Na-Na and Na-O bond lengths during compression. A subsequent decomposition of the glassy matrix into elementary Voronoi volumes verifies the high compressibility of Na-rich regions.
RESUMEN
In this paper we analyze results of Molecular Dynamics simulations of Vickers nanoindentation, performed for sodium borosilicate glasses of interest in the nuclear industry. Three glasses have been studied in their pristine form, as well as a disordered one that is analogous to the real irradiated glass. We focused in the behavior of the glass during the nanoindentation in order to reveal the mechanisms of deformation and how they are affected by microstructural characteristics. Results have shown a strong dependence on the SiO2 content of the glass, which promotes densification due to the open structure of SiO4 tetrahedra and also due to the strength of Si-O bonds. Densification for the glasses is primarily expressed by the relative decrease of the Si-O-Si and Si-O-B angles, indicating rotation of the structural units and decrease of free volume. The increase of alkali content on the other hand results to higher plasticity of the matrix and increased shear flow. The most important effect on the deformation mechanism of the disordered glasses is that of the highly depolymerized network that will also induce shear flow and, in combination with the increased free volume, will result in the decreased hardness of these glasses, as has been previously observed.
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Angioplastia de Balón/instrumentación , Embolización Terapéutica , Corteza Renal/irrigación sanguínea , Obstrucción de la Arteria Renal/terapia , Arteria Renal/lesiones , Anciano , Hematoma/diagnóstico por imagen , Hematoma/terapia , Humanos , Masculino , Radiografía , Arteria Renal/diagnóstico por imagen , Obstrucción de la Arteria Renal/diagnóstico por imagen , RetratamientoRESUMEN
Azathioprine (AZA) is metabolized via the cytosolic enzyme thiopurine S-methyltransferase (TPMT). TPMT activity exhibits genetic polymorphism with four prevalent (75%) mutant alleles TPMT*2 (G238C) and TPMT*3 (A719G and/or G460A) and a wild-type allele TPMT*1. To test the hypothesis that presence of these mutations is associated with greater toxicity of AZA in heart transplant recipients, 30 consecutive patients treated with AZA were followed up for the first month after heart transplant. Mutation of TPMT gene (mutation-specific polymerase chain reaction-based methods) was observed in four patients (A719G: n = 2; A719G plus G460: n = 2). Agranulocytosis did not occur in patients with the wild genotype. It occurred in the two patients with mutation A719G and there was a 40% drop in neutrophils in the two other patients. Discontinuation of AZA in the four mutant patients corrected for the drop. Presence of TPMT mutations is associated with a greater likelihood of agranulocytosis. Determination of these mutations could reduce the risk for hematological side-effects.
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Azatioprina/uso terapéutico , Médula Ósea/efectos de los fármacos , Trasplante de Corazón , Inmunosupresores/uso terapéutico , Metiltransferasas/genética , Polimorfismo Genético , Adulto , Agranulocitosis/inducido químicamente , Médula Ósea/patología , Femenino , Predicción , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Estudios RetrospectivosRESUMEN
OBJECTIVES: The purpose of this study was to assess the quality of the management of infective endocarditis. BACKGROUND: Although many guidelines on the management of infective endocarditis exist, the quality of this management has not been evaluated. METHODS: We collected data on all patients (116) hospitalized with infective endocarditis over 1 year in all hospitals in the Rhône-Alpes region (France). RESULTS: Prophylactic antibiotics were not given before infective endocarditis to 8/11 cardiac patients at risk and who underwent an at risk procedure. Among the 55 cardiac patients at risk and with fever and who consulted a physician, blood cultures were not performed before antibiotic therapy was initiated for 32 patients. In-hospital antibiotic therapy was incorrect for 23 patients. The portal of entry was not treated for 16/61 patients with an accessible portal of entry. Among the 19 patients who had severe heart failure or fever persisting more than 2 weeks in spite of antibiotic therapy and who could have undergone early surgery, surgery was delayed for five, and not performed for three. Overall, the average score was 15/20. CONCLUSIONS: More information on the management of infective endocarditis should be widely disseminated to the physicians' and the dentists' communities and to the patients at risk.
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Antibacterianos/uso terapéutico , Procedimientos Quirúrgicos Cardíacos , Endocarditis Bacteriana/terapia , Garantía de la Calidad de Atención de Salud , Anciano , Endocarditis Bacteriana/epidemiología , Femenino , Francia/epidemiología , Hospitalización , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Vigilancia de la Población , Pronóstico , Estudios Prospectivos , Tasa de SupervivenciaRESUMEN
BACKGROUND: The Lyon Diet Heart Study is a randomized secondary prevention trial aimed at testing whether a Mediterranean-type diet may reduce the rate of recurrence after a first myocardial infarction. An intermediate analysis showed a striking protective effect after 27 months of follow-up. This report presents results of an extended follow-up (with a mean of 46 months per patient) and deals with the relationships of dietary patterns and traditional risk factors with recurrence. METHODS AND RESULTS: Three composite outcomes (COs) combining either cardiac death and nonfatal myocardial infarction (CO 1), or the preceding plus major secondary end points (unstable angina, stroke, heart failure, pulmonary or peripheral embolism) (CO 2), or the preceding plus minor events requiring hospital admission (CO 3) were studied. In the Mediterranean diet group, CO 1 was reduced (14 events versus 44 in the prudent Western-type diet group, P=0.0001), as were CO 2 (27 events versus 90, P=0.0001) and CO 3 (95 events versus 180, P=0. 0002). Adjusted risk ratios ranged from 0.28 to 0.53. Among the traditional risk factors, total cholesterol (1 mmol/L being associated with an increased risk of 18% to 28%), systolic blood pressure (1 mm Hg being associated with an increased risk of 1% to 2%), leukocyte count (adjusted risk ratios ranging from 1.64 to 2.86 with count >9x10(9)/L), female sex (adjusted risk ratios, 0.27 to 0. 46), and aspirin use (adjusted risk ratios, 0.59 to 0.82) were each significantly and independently associated with recurrence. CONCLUSIONS: The protective effect of the Mediterranean dietary pattern was maintained up to 4 years after the first infarction, confirming previous intermediate analyses. Major traditional risk factors, such as high blood cholesterol and blood pressure, were shown to be independent and joint predictors of recurrence, indicating that the Mediterranean dietary pattern did not alter, at least qualitatively, the usual relationships between major risk factors and recurrence. Thus, a comprehensive strategy to decrease cardiovascular morbidity and mortality should include primarily a cardioprotective diet. It should be associated with other (pharmacological?) means aimed at reducing modifiable risk factors. Further trials combining the 2 approaches are warranted.
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Dieta , Infarto del Miocardio , Anciano , Angina Inestable/mortalidad , Presión Sanguínea , Trastornos Cerebrovasculares/mortalidad , Colesterol/sangre , Enfermedad Coronaria/dietoterapia , Enfermedad Coronaria/mortalidad , Enfermedad Coronaria/prevención & control , Ingestión de Alimentos , Ácidos Grasos/sangre , Femenino , Estudios de Seguimiento , Insuficiencia Cardíaca/mortalidad , Humanos , Masculino , Región Mediterránea , Persona de Mediana Edad , Análisis Multivariante , Infarto del Miocardio/dietoterapia , Infarto del Miocardio/mortalidad , Infarto del Miocardio/prevención & control , Embolia Pulmonar/mortalidad , Recurrencia , Factores de Riesgo , Método Simple Ciego , Fumar , Análisis de SupervivenciaRESUMEN
BACKGROUND & AIMS: Hepatic involvement in hereditary hemorrhagic telangiectasia is common but often asymptomatic. However, in some cases, the vascular lesions that involve the liver may lead to high-output cardiac failure and pulmonary hypertension that is predominant over hepatobiliary manifestations. Liver transplantation and treatment of these complications are described and discussed in this article. METHODS: Three patients with hereditary hemorrhagic telangiectasia and hepatic involvement received transplants. They had pulmonary hypertension and chronic right-sided heart failure caused by disseminated intrahepatic telangiectasias with shunts between the hepatic artery and hepatic veins or portal vein. Left-to-right intrahepatic shunt output was estimated to range between 51% and 57.5% of cardiac output. RESULTS: Hyperdynamic circulation disappeared after liver transplantation in all patients. Results of computed tomography and right-sided heart catheterization performed 6 months later were normal. Follow-up periods currently are 65, 53, and 29 months, and each patient continues to be asymptomatic. CONCLUSIONS: This report suggests that liver transplantation can be considered as an alternative and successful curative treatment that may prevent the irreversible evolution of cardiopulmonary disease.
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Circulación Hepática , Trasplante de Hígado , Telangiectasia Hemorrágica Hereditaria/fisiopatología , Telangiectasia Hemorrágica Hereditaria/cirugía , Adulto , Femenino , Insuficiencia Cardíaca/complicaciones , Insuficiencia Cardíaca/prevención & control , Hemodinámica/fisiología , Humanos , Hipertensión Pulmonar/complicaciones , Pruebas de Función Hepática , Persona de Mediana Edad , Pruebas de Función Respiratoria , Telangiectasia Hemorrágica Hereditaria/complicaciones , Tomografía Computarizada por Rayos XRESUMEN
Because cardiac complications after myocardial infarction are more frequent in diabetics, we tested whether experimentally-induced diabetes may increase ischaemic myocardial injury in 23 rabbits. Diabetes was induced in randomized rabbits with the alloxan method. After 2 months, diabetic rabbits underwent a 30-min coronary occlusion followed by 3-h reperfusion and were compared with controls. Collateral flow was measured by the radioactive microsphere technique and infarct size by tetrazolium staining. Infarct size represented 28.6+/-4% of area-at-risk in controls and 16.5+/-3% in diabetics (P<0.05). Collateral flow (0.06+/-0.03 ml/min/g in controls and 0.014+/-0.004 ml/min/g in diabetics) and area-at-risk (50.2+/-4.2% of left ventricle in controls and 53.9+/-5. 4% in diabetics) were similar in both groups. There was a significant positive correlation between area-at-risk and infarct size in both groups (r=0.60 and 0.70, respectively) and for a given area-at-risk, diabetic rabbits developed smaller myocardial infarction than controls (covariance analysis, P<0.01). In additional experiments, hyperglycemia induced by intravenous glucose infusion in non-diabetic rabbits did not protect the ischaemic myocardium (infarct size: 37.9+/-12.5%). In conclusion, diabetes in the rabbit induces a chronic and metabolic form of preconditioning. Further studies are needed to explore the mechanism and time course of this protection.
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Diabetes Mellitus Experimental/fisiopatología , Corazón/fisiopatología , Infarto del Miocardio/fisiopatología , Animales , Circulación Colateral , Circulación Coronaria , Precondicionamiento Isquémico Miocárdico , Masculino , ConejosRESUMEN
In this study, we examined whether chronic severe diabetes may affect ischaemic and post-ischaemic regional myocardial dysfunction in vivo in the dog. Diabetes was chemically induced in randomized animals and major metabolic alterations were observed confirming the severity and chronicity of the diabetes. After 70 days, halothane-anaesthetized dogs underwent a 20-min coronary occlusion, followed by reperfusion. During ischaemia, global left ventricle function (dP/dtmax) was more altered (P<0.005) in diabetics ( n=10) than in controls (n=10), whereas area-at-risk (29+/-2.5% of the left ventricle in diabetics v 32.4+/-1.9% in controls) and ischaemic subendocardial myocardial blood flow (radioactive microsphere technique, 0.11+/-0.02 v 0.10+/-0.03 ml/min/g) were similar. During reperfusion, both groups developed significant (P<0.05) regional myocardial dysfunction (somomicrometry, 41+/-14% of baseline in controls and 66+/-8% in diabetics), whereas the difference between groups was not significant. No dog of either group developed myocardial cell necrosis on tissue histology. Multivariate analyses, including the severity of prior ischaemia and the occurrence of ventricular fibrillation as covariables, confirmed that myocardial stunning was not increased in diabetics, although ischaemia was clearly less-well-tolerated in diabetic dogs as global (dP/dtmax) as well as regional myocardial function were significantly (P<0.05) more altered in diabetics during ischaemia. Whilst alteration of arachidonate and cholesterol metabolism may partly explain this apparent paradox, further studies are required to resolve this issue.
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Diabetes Mellitus Experimental/complicaciones , Aturdimiento Miocárdico/complicaciones , Animales , Circulación Coronaria , Diabetes Mellitus Experimental/fisiopatología , Perros , Femenino , Corazón/fisiopatología , Masculino , Contracción Miocárdica , Infarto del Miocardio/complicaciones , Aturdimiento Miocárdico/fisiopatología , Flujo Sanguíneo RegionalRESUMEN
Eight randomised clinical trials of angiotensin converting enzyme (ACE) inhibitors versus placebo in myocardial infarction have been published in three years, including over 100,000 patients. High risk myocardial infarction carries a poor prognosis with a 25% death rate at 42 months in SAVE, 23% at 15 months in AIRE and 42% at 37 months in TRACE. This form of myocardial infarction benefits the most from treatment with ACE inhibitors: the relative reductions in risk for the previously mentioned trials were 19%, 27% and 22% respectively, and the absolute reductions in risk of death were 4% at 42 months, 6% at 15 months and 8% at 37 months, respectively. Studies including all forms of myocardial infarction involve populations at lower risk. The effects of ACE inhibitors on mortality are then less obvious: from 7.7% to 7.2% at 5 weeks in ISIS-4, from 7.1% to 6.3% at 6 weeks in GISSI-3, from 9.6% to 9.0% at 4 weeks in CCS-1, corresponding to relative reductions in the risk of death of 7%, 12% and 3% respectively and absolute reductions of the risk of death of 0.5% at 5 weeks, 0.8% at 6 weeks and 0.6% at 4 weeks, respectively. Who should be treated? All patients for 4 to 6 weeks or only high risk patients. When should treatment be started? Some investigators institute treatment from the first day but others think it prudent to wait until the second day. For how long? Four to 6 weeks would be sufficient to counteract ventricular remodelling while the benefits are sustained in the long term. But treatment should be continued long term in high risk patients. Which molecule, which dose and how many times, should it be taken per day? The logical answer is molecules with proven efficacy at the dose given in the clinical trials respecting the number of times indicated per day.
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Inhibidores de la Enzima Convertidora de Angiotensina/uso terapéutico , Infarto del Miocardio/tratamiento farmacológico , Humanos , Infarto del Miocardio/fisiopatología , Ensayos Clínicos Controlados Aleatorios como Asunto , Riesgo , Análisis de SupervivenciaRESUMEN
The objective of this study was to evaluate the effects of ticlopidine on the generation of eicosanoids and nitric oxide in heart-transplant recipients. In a randomized double-blind study, we studied the urinary excretion of the stable metabolites of thromboxane, prostacyclin, and nitric oxide before and after ticlopidine (250 mg/day). Platelet aggregation was significantly reduced in ticlopidine-treated patients [from 40.2 +/- 24.2% of maximal aggregation to 14.7 +/- 8.2% in response to adenosine diphosphate (ADP); p < 0.001] but not in the placebo group, confirming the efficacy of the drug with that dosage in these specific patients. The 24-h urinary excretion of prostacyclin metabolites was not modified by ticlopidine (1,865 +/- 833 ng/24 h at day 14 and 1,664 +/- 425 ng/24 h at day 0), whereas the excretion of thromboxane B2 tended to increase in the ticlopidine group (from 3,854 +/- 1,163 ng/24 h at day 0 to 5,014 +/- 2,914 ng/24 h at day 14), although not significantly. The excretion of nitric oxide metabolites (although not different from that of healthy nonimmunosuppressed subjects) was significantly (p < 0.005) increased in the ticlopidine group (from 3,082 +/- 1,683 micromol/24 h at day 0 to 4,133 +/- 2,262 micromol/24 h at day 14), but not in controls. Thus ticlopidine does not reduce prostacyclin but increases the systemic generation of nitric oxide, both substances having major antiplatelet and vasodilator properties. Further studies are warranted to examine whether ticlopidine could reduce the incidence of thromboembolic complications in these patients and whether this possible novel property of ticlopidine is restricted to immunosuppressed heart-transplant recipients.
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Óxido Nítrico/metabolismo , Inhibidores de Agregación Plaquetaria/farmacología , Ticlopidina/farmacología , Análisis de Varianza , Plaquetas/efectos de los fármacos , Plaquetas/metabolismo , Método Doble Ciego , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/metabolismo , Epoprostenol/orina , Trasplante de Corazón , Humanos , Terapia de Inmunosupresión , Masculino , Óxido Nítrico/orina , Tromboxanos/orinaRESUMEN
We investigated the possibility that dietary cholesterol downregulates the expression of low density lipoprotein (LDL) receptor and 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase genes of circulating mononuclear cells in vivo in healthy humans. We also studied the variations of the LDL receptor-related protein (LRP) gene in the same conditions. Dieters (n = 5) were submitted to a 4-d fat restriction (mean cholesterol intake: 6+/-4 mg/d), followed by a 7-d cholesterol (a mean of 791+/-150 mg/d) supplementation. Controls (n = 3) did not change their diet. During fat restriction, serum total and LDL cholesterol decreased significantly (P < 0.05), and LDL receptor and HMG-CoA reductase mRNA copy numbers in mononuclear cells increased by 57 and 147%, respectively (P < 0.05). After reintroducing cholesterol, serum cholesterol was stable whereas LDL receptor and HMG-CoA reductase mRNA decreased by 46 and 72% (P < 0.05) and LRP mRNA increased by 59% (P < 0.005). The changes in LDL receptor and HMG-CoA reductase mRNA abundance were correlated (r = +0.79, P = 0.02) during cholesterol reintroduction as were LDL receptor and LRP mRNA levels, but negatively (r = -0.70, P = 0.05). Also, 70% of the variability in LRP mRNA (P < 0.005) was explained by dietary cholesterol. Thus, the basic mechanisms regulating cellular cholesterol content, the coordinate feedback repression of genes governing the synthesis and uptake of cholesterol, are operating in vivo in humans. However, serum cholesterol did not increase in response to dietary cholesterol, suggesting that these mechanisms may not play as predominant a role as previously believed in the short-term control of serum cholesterol in vivo in humans. A new finding is that LRP gene is also sensitive to dietary cholesterol, suggesting that it may participate in the control of serum cholesterol. Further in vivo studies in humans are warranted to explore the molecular mechanisms of the physiological response to dietary cholesterol in humans.
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Colesterol en la Dieta/administración & dosificación , Hidroximetilglutaril-CoA Reductasas/sangre , ARN Mensajero/genética , Receptores Inmunológicos/sangre , Receptores de LDL/sangre , Adulto , Secuencia de Bases , Cartilla de ADN , Ácidos Grasos/sangre , Humanos , Hidroximetilglutaril-CoA Reductasas/genética , Proteína 1 Relacionada con Receptor de Lipoproteína de Baja Densidad , Masculino , Persona de Mediana Edad , Receptores Inmunológicos/genética , Receptores de LDL/genética , Valores de ReferenciaRESUMEN
Recent clinical and experimental studies have suggested that antioxidant supplements might actually have harmful as well as beneficial effects in the setting of cardiovascular disease. The mechanisms underlying the beneficial effects of the various antioxidants are poorly understood in humans. Reperfusion-associated myocardial injury, and particularly the phenomenon of stunning, is important because it occurs in clinical settings and may condition the prognosis after short ischemic insult. We studied the effects of chronic (3 months) alpha-tocopherol supplementation with a large oral dose (500 mg daily) on myocardial contractility (stunning) and ventricular arrhythmias in a dog model of short ischemia followed by reperfusion. Twenty dogs were randomized to either an alpha-tocopherol supplemented or a control group. After 3 months, dogs were anesthetized and underwent a 20-min coronary artery occlusion followed by reperfusion. Myocardial regional blood flow was measured by the radioactive microsphere technique and myocardial contractility by sonomicrometry. Plasma alpha-tocopherol was measured by high-performance liquid chromatography in all dogs. Twelve dogs (seven supplemented and five controls) developed ventricular fibrillation at reperfusion, showing no difference between groups. Hemodynamic parameters, blood flow in the ischemic area (collateral flow), and area at risk were similar in the two groups. Regional systolic segment shortening in the ischemic area was similar during ischemia and reperfusion in both groups, representing 41 +/- 15% (mean +/- SEM) of baseline contractility in controls and 51 +/- 8% in supplemented dogs after 150 min of reperfusion. Plasma alpha-tocopherol level was higher in supplemented than in controls (19.1 +/- 1.6 and 6.9 +/- 0.6 mg/L; p < 0.001). Thus a long-term large dose of alpha-tocopherol had no significant effect on postischaemic ventricular arrhythmias and dysfunction (myocardial stunning) in this canine model. These data suggest that if alpha-tocopherol supplementation might be useful to improve the prognosis of coronary patients, it is likely not by interfering with the stunning phenomenon.