Evaluation of low-density lipoprotein particle number distribution in patients with type 2 diabetes mellitus with low-density lipoprotein cholesterol <50 mg/dl and non-high-density lipoprotein cholesterol <80 mg/dl.

Many patients with type 2 diabetes mellitus (T2DM) have relatively normal levels of low-density lipoprotein (LDL) cholesterol yet have increased risk for cardiovascular events. Distribution of lipoprotein subclasses in patients with T2DM who have achieved very low levels of LDL cholesterol (<50 mg/dl) or non-high-density lipoprotein (HDL) cholesterol (<80 mg/dl) have not been extensively examined. The aim of this study was to assess variations in lipoprotein particle concentration in patients with diabetes with "very low" LDL cholesterol and non-HDL cholesterol levels to elucidate the drivers of residual cardiovascular risk. Data were selected from a single large clinical laboratory database. Cases were patients with T2DM diagnosis codes (International Classification of Diseases, Ninth Revision, codes 250 to 250.93). Lipoprotein particle concentrations were analyzed using nuclear magnetic resonance spectroscopy. The Friedewald equation was used to calculate LDL cholesterol. Among the 1,970 patients with T2DM, the mean age was 61 years, and approximately 51% were men. At LDL cholesterol concentrations <50 mg/dl (triglyceride <150 mg/dl and HDL cholesterol >40 mg/dl), 16% had LDL particle concentrations <500 nmol/L, 70% had concentrations of 500 to 1,000 nmol/L, and 14% had concentrations >1,001 nmol/L. At non-HDL cholesterol levels <80 mg/dl, 8% had LDL particle concentrations <500 nmol/L, 67% had concentrations of 500 to 1,000 nmol/L, and 25% had concentrations >1,001 nmol/L. In conclusion, despite attainment of LDL cholesterol <50 mg/dl or non-HDL cholesterol <80 mg/dl, patients with diabetes exhibited significant variation in LDL particle levels, with most having LDL particle concentrations >500 nmol/L, suggesting the persistence of potential residual coronary heart disease risk.

Bradykinin and its metabolite bradykinin 1-5 inhibit thrombin-induced platelet aggregation in humans.

Bradykinin 1-5 is a major stable metabolite of bradykinin, formed by the proteolytic action of angiotensin-converting enzyme. In vitro and animal studies suggest that bradykinin 1-5 possesses biological activity. This study tests the hypothesis that bradykinin 1-5 affects vasodilation, fibrinolysis, or platelet aggregation in humans. Graded doses of bradykinin (47-377 pmol/min) and bradykinin 1-5 (47-18,850 pmol/min) were infused in the brachial artery in random order in 36 healthy subjects. Forearm blood flow (FBF) was measured, and simultaneously obtained venous and arterial plasma samples were analyzed for tissue plasminogen activator (t-PA) antigen. In seven subjects each, alpha- and gamma-thrombin-induced platelet aggregation was measured in platelet-rich plasma obtained from antecubital venous blood at baseline and during peptide infusions. Bradykinin caused dose-dependent increases in FBF and net t-PA release (P < 0.001 for both). Bradykinin 1-5 did not affect FBF (P = 0.13) or net t-PA release (P = 0.46) at concentrations >1500 times physiologic. In contrast, both bradykinin and bradykinin 1-5 inhibited alpha-and gamma-thrombin-induced platelet aggregation (P < 0.01 versus baseline). Bradykinin 1-5 inhibited gamma-thrombin-induced platelet aggregation 50% at a calculated dose of 183 +/- 3 pmol/min. Neither bradykinin nor bradykinin 1-5 affected thrombin receptor-activating peptide-induced platelet aggregation, consistent with the hypothesis that bradykinin and bradykinin 1-5 inhibit thrombin-induced platelet aggregation by preventing cleavage of the thrombin receptor and liberation of thrombin receptor-activating peptide. This study is the first to demonstrate biological activity of bradykinin 1-5 following in vivo administration to humans. By inhibiting thrombin-induced platelet aggregation without causing vasodilation, bradykinin 1-5 may provide a model for small molecule substrate-selective thrombin inhibitors.

Relationship between carbamoyl-phosphate synthetase genotype and systemic vascular function.

Endothelial cells can convert l-citrulline to l-arginine, the precursor of nitric oxide. The present study tests the hypothesis that a C-to-A nucleotide transversion (T1405N) in the gene-encoding carbamoyl-phosphate synthetase 1, the enzyme catalyzing the rate-limiting step in l-citrulline formation, influences nitric oxide metabolite concentrations or nitric oxide-mediated vasodilation in humans. Bradykinin (100, 200, and 400 ng/min) was infused via brachial artery in 106 (CC:AC:AA=40:54:12) healthy subjects. Sodium nitroprusside (1.6, 3.2, and 6.4 microg/min) was also infused in 87 (CC:AC:AA=31:46:10) subjects. Forearm blood flow was measured by plethysmography and blood samples were collected for tissue-type plasminogen activator antigen, nitric oxide metabolites, and cyclic GMP. There was a significant relationship between carbamoyl-phosphate synthetase 1 genotype and nitric oxide metabolites, such that nitric oxide metabolite concentrations were highest in individuals homozygous for the C allele (mean+/-SD, 14.0+/-8.5 micromol/L), lowest in individuals homozygous for the A allele (9.1+/-3.1 micromol/L), and intermediate (11.8+/-6.6 micromol/L) in heterozygotes (P=0.036). There was a significant effect of carbamoyl-phosphate synthetase 1 genotype on forearm blood flow during bradykinin (P=0.028), such that the vasodilator response was greatest in C allele homozygotes (22.2+/-9.1 mL/min/100 mL at 400 ng/min), least in A allele homozygotes (13.6+/-6.2 mL/min/100 mL), and intermediate (19.4+/-10.7 mL/min/100 mL) in heterozygotes. Similarly, carbamoyl-phosphate synthetase 1 genotype influenced forearm blood flow during nitroprusside (maximal flow 19.2+/-8.3, 18.1+/-8.3, and 11.5+/-4.9 mL/min/100 mL in the CC:AC:AA groups, respectively; P=0.022). In contrast, there was no effect of carbamoyl-phosphate synthetase 1 genotype on the nitric oxide-independent tissue-type plasminogen activator response to bradykinin (P=0.943). These data indicate that a polymorphism in the gene encoding carbamoyl-phosphate synthetase 1 influences nitric oxide production as well as vascular smooth muscle reactivity.

Circulating levels of tumor necrosis factor correlate with indexes of depressed heart rate variability: a study in patients with mild-to-moderate heart failure.

OBJECTIVES: Patients with heart failure have increased circulating levels of tumor necrosis factor (TNF) and TNF receptors. It is not known whether TNF, which is known to blunt beta-adrenergic responsiveness in experimental models, contributes to the loss of heart rate variability in patients with heart failure. Therefore, we examined heart rate variability in relation to circulating levels of TNF, TNF receptors, and norepinephrine in patients with heart failure and in control subjects. METHODS: Heart rate variability was obtained from 24-h ambulatory ECG recordings in age-matched control subjects (n = 10) and patients with mild (n = 15) to moderate (n = 14) heart failure. Plasma levels of TNF and soluble type 1 and 2 TNF receptors were measured by enzyme-linked immunoassay; plasma norepinephrine levels were measured by high-performance liquid chromatography. RESULTS: There was a significant inverse linear correlation between increased circulating levels of TNF, TNF receptors, and norepinephrine for time-domain and frequency-domain indexes of heart rate variability among patients with heart failure and control subjects. Multiple stepwise linear regression analysis showed that TNF was a stronger independent predictor of frequency-domain indexes of heart rate variability than norepinephrine. CONCLUSIONS: TNF is an independent predictor of depressed heart rate variability in patients with heart failure. Insofar as TNF blunts beta-adrenergic signaling, this study suggests the possibility that overexpression of TNF and subsequent loss of beta-adrenergic responsiveness contributes to the decrease in heart rate variability observed in heart failure.

Efectos de las grasas y otros nutrientes sobre la carcinogenesis colorrectal: revisión de la literatura / Effect of fats and other nutrients over colorectal carcinogenesis: review of the literature

La incidencia y mortalidad por cáncer colorectal es mayor en las sociedades desarrolladas e industrializadas que en las poblaciones rurales y del tercer mundo. En esto juega papel fundamental diferencias en la dieta y en especial en la ingesta de grasas, proteínas, fibras y algunos micronutrientes. En numerosos trabajos se ha analizado la relación entre la ingesta de diferentes tipos de grasas y la carcinogénesis colorectal. En general, las grasas saturadas, de origen animal, han sido señaladas como promotoras y las grasas poliinsaturadas como protectoras del desarrollo de cáncer colorrectal. Sin embargo estudios experimentales han mostrado efecto carcinogénico de las grasas poliinsaturadas y trabajos epidemiológicos en poblaciones subdesarrolladas con baja ingesta lipídica, demostraron correlación positiva significativa entre el consumo de grasas poliinsaturadas y la mortalidad por cáncer colorrectal. La ingesta elevada de grasas aumenta la excreción de ácidos biliares, la formación de ácidos biliares secundarios, la proporción de bacterias anaeróbicas y la producción de genotoxinas, diacilglicerol y radicales libres capaces de determinar daño celular. Por otra parte, es conocido el efecto protector de las fibras, que aumentan la fermentación bacteriana, disminuyendo el pH intestinal, aumentando el volumen fecal y acelerando el tránsito intestinal. La restricción del consumo proteico al igual que la ingestion de algunos micronutrientes como vitaminas, metales trazas y electrolitos, tienen efectos sobre la carcinogenesis colorrectal

Feocromocitotoma bilateral maligno como componentes de adenomatosis endocrina multiple tipo II-A: presentacion de un caso y revision de la literatura / Bilateral malignant pheochromocytoma as component of multiple endocrine adenmatosis type II-A: presentation of a case and review of the literature

Se presenta el caso de un joven de 25 anos hospitalizado por un cuadro de hipertension arterial sistemica severa acompanado de bocio multinodular, a quien se le diagnostico adenomatosis endocrina multiple tipo II-A (AEM II-A). Se comprobo la presencia de feocromocitoma bilateral metastasico al encontrarse niveles elevados de acido venilmandelico en orina, dos masas suprarrenales bilaterales y una masa tumoral hepatica en el estudio tomografico de abdomen. En forma similar se evidenciaron nodulos hipocaptantes en tiroides, demostrandose que correspondian a un carcinoma medular de tiroides al realizar el estudio histopatologico. se logro el control de las cifras tensionales con la administracion de prazosin (12 mg/da) y labetalol (600 mg/dia) en el periodo preoperatorio, practicandose posteriormente la adrenalectomia subtotal bilateral y tiroidectomia total. En su evolucion postoperatoria el paciente presento episodios de hemorragia digestiva superior masiva debidos a multiples ulceras del tracto gastrointestinal, que ameritaron realizar una gastrectomia total para el control de la hemorragia. Se hace revision de la literatura con referencia particular al diagnostico y manejo del feocromocitoma maligno

Relación entre el consumo de grasas y la mortalidad por cáncer colorrectal en la población venezolana / Fat intake and colorectal mortality in the Venezuela population

Estudios epidemiológicos y de laboratorio han indicado que existe una asociación entre la ingesta de grasa en la dieta y la carcinogénesis colorectal. En el presente estudio se evalúa la relación existente entre el consumo de grasas en la población venezolana y la mortalidad por cancer colorectal en la misma. Para ello, se establecieron los coeficientes de correlación entre la ingesta de grasas visibles (aceites vegetales, margarina, mantequilla, manteca vegetal y animal, mayonesa) y grasas no visibles (aquellas contenidas en los restantes alimentos), y las tasas de mortalidad específica por cáncer colorrectal en 9 Estados y Regiones Geopolíticas de Venezuela. El mayor consumo lipídico y las tasas de mortalidad más elevadas por cáncer colorectal se observaron en los estados más desarrollados. Se observó una correlación positiva significativa entre el consumo de grasas totales y grasas visibles y la mortalidad por cáncer colorrectal (r = 0,756; p 0,02 y r = 0,958; p < 0,001 respectivamente). Por otra parte no se observó correlación significativa entre el consumo de grasas no visibles y la mortalidad por cáncer colorrectal (r = 0,543, p > 0,05). Más del 80% de los lípidos que conforman las grasas visibles que se consumen en Venezuela, están constituidos por aceites vegetales y margarina, los cuales contienen en su mayor parte ácidos grasos poliinsaturados. Basado en lo anterior, es posible inferir que la carcinogénesis colorrectal en Venezuela está vinculada al consumo de grasas insaturadas, y que las medidas tendientes a prevenir esta enfermedad deben basarse en la reducción del consumo de las mismas