RESUMO
Ascorbic acid (AA) is a major redox buffer in plant cells. The role of ethylene in the redox signaling pathways that influence photosynthesis and growth was explored in two independent AA deficient Arabidopsis thaliana mutants (vtc2-1 and vtc2-4). Both mutants, which are defective in the AA biosynthesis gene GDP-L-galactose phosphorylase, produce higher amounts of ethylene than wt plants. In contrast to the wt, the inhibition of ethylene signaling increased leaf conductance, photosynthesis and dry weight in both vtc2 mutant lines. The AA-deficient mutants showed altered expression of genes encoding proteins involved in the synthesis/responses to phytohormones that control growth, particularly auxin, cytokinins, abscisic acid, brassinosterioids, ethylene and salicylic acid. These results demonstrate that AA deficiency modifies hormone signaling in plants, redox-ethylene interactions providing a regulatory node controlling shoot biomass accumulation.
Assuntos
Proteínas de Arabidopsis/genética , Ácido Ascórbico/metabolismo , Etilenos/metabolismo , Monoéster Fosfórico Hidrolases/genética , Reguladores de Crescimento de Plantas/metabolismo , Ácido Abscísico/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Ácido Ascórbico/genética , Biomassa , Regulação da Expressão Gênica de Plantas , Mutação , Oxirredução , Monoéster Fosfórico Hidrolases/metabolismo , Fotossíntese/genética , Reguladores de Crescimento de Plantas/genética , Ácido Salicílico/metabolismo , Transdução de Sinais/genéticaRESUMO
The aim of the present study was to determine in adolescents the relationship between insulin levels and body mass index (BMI), body fat distribution, diet, life style and lipid profile. We studied 167 adolescents (68 boys and 99 girls) whose ages ranged from 14 to 17 years. A detailed medical (including pubertal stage) and nutritional record was obtained from each subject. Biochemical measurements included fasting serum insulin, glucose, total cholesterol (TC), triglycerides (Tg), HDL-C, LDL-C and VLDL-C. HOMA insulin resistance (IR) and HOMA beta-cell function (beta-cell) were calculated. Insulin levels were over 84 pmol/L (cut off normal value in our lab) in 56 per cent of the boys and 43 per cent of the girls. Thirty-seven percent of lean adolescents whose BMI was 21.5 +/- 1.9 kg/m2 presented higher fasting insulin levels. HOMA IR, Tg, systolic (SBP) and diastolic blood pressure (DBP) values when compared to a lean normoinsulinemic group. Insulin levels were correlated (p < 0.01) with body mass index. Both boys and girls in the highest BMI quartile (BMI > 24 kg/m2) had significantly higher serum insulin, HOMA beta-cell, and Tg levels, and the lowest HDL-C levels. A high-energy intake rich in saturated fat and low physical activity were found in this lean but metabolically altered adolescents. We conclude that even with a BMI as low as 21 kg/m2 an inappropriate diet and low physical activity might be responsible for the high insulin levels and dislipidemias in adolescents.
Assuntos
Humanos , Masculino , Feminino , Adolescente , Magreza/metabolismo , Síndrome Metabólica/etiologia , Pressão Arterial , Índice de Massa Corporal , Dieta , Exercício Físico , Insulina/sangue , Insulina/metabolismo , Estilo de Vida , Lipídeos/sangue , Lipídeos/metabolismo , Fatores de Risco , Síndrome Metabólica/sangueRESUMO
With the purpose of determining how certain risk factors for type 2 diabetes such as family history of diabetes, obesity and dyslipidemia, affect the glucose-insulin response to a glucose challenge, 135 individuals (77 women and 58) men were studied. Their ages ranged from 20-68 years, their basal glycemic values were less than 110 mg/dL but they were considered at risk for diabetes due to the presence of one or more of those factors. We found that the presence of those risk factors did not affect the glycemic response in any case. However, the basal insulin levels as well as the post-challenge values were increased significantly (p < 0.0001) by the presence of obesity in men as well as in women. Dyslipidemia increased the basal and post challenge glucose insulin values only in men (p < 0.002). The coexistence of obesity and family history of diabetes provoked a decrease in the basal insulin levels as well as in the insulin response to glucose. We conclude that, without alteration of the glycemic response, the presence of risk factors as obesity, dyslipidemia or family history of diabetes leads to basal hyperinsulinemia, as well as glucose stimulated hyperinsulinemia, however the coexistence of obesity and family history of diabetes, is responsible for a deficit in the insulin secretion by the pancreas.
Assuntos
Glicemia/análise , Diabetes Mellitus Tipo 2/epidemiologia , Teste de Tolerância a Glucose , Hiperinsulinismo/epidemiologia , Insulina/análise , Estado Pré-Diabético/epidemiologia , Adulto , Idoso , Índice de Massa Corporal , Comorbidade , Diabetes Mellitus Tipo 2/genética , Suscetibilidade a Doenças , Jejum/sangue , Feminino , Predisposição Genética para Doença , Glucose , Humanos , Hiperinsulinismo/diagnóstico , Hiperinsulinismo/genética , Hiperlipidemias/epidemiologia , Hipertensão/epidemiologia , Resistência à Insulina , Masculino , Pessoa de Meia-Idade , Obesidade/sangue , Obesidade/epidemiologia , Estado Pré-Diabético/sangue , Estado Pré-Diabético/diagnóstico , Estado Pré-Diabético/genética , Fatores de RiscoRESUMO
Hyperinsulinemia and impaired insulin action are familial and predictive of Type 2 diabetes onset. Since high levels of insulin are characteristic of our general (venezuelan)hispanic population, the purpose of this investigation was to identify early metabolic defects in a group of healthy first degree relatives of Type 2 diabetic patients. We studied 46 (29 women and 17 men; ages ranging 18-66 y) first degree relatives of Type 2 diabetic patients comparing them with 22 (12 women and 10 men; ages ranging 22-60 y) subjects who had no family history of diabetes. All subjects underwent resting blood pressure and anthropometric measurements; a 75 g oral glucose tolerance test with determination of glucose and insulin and a fasting lipid profile. The relatives of Type 2 diabetic patients had higher tricipital (TC) and subscapular (SC) skinfolds, and elevated DBP in relation to the control group. The skinfolds elevation was more evident in women, while in men the elevation in DBP predominates. None of the relatives had glucose intolerance, however, the glucose-stimulated insulin response was elevated at all points in men as well as in women. No difference was observed in the HOMA values for IR and beta cell function, or in the delta I30/delta G30 ratio. The lipid profile showed a marked elevation in TG levels in men as well as in women, with low HDL-C values in men. No other lipid abnormalities were observed. Correlation analysis revealed strong association between BMI and WHR with skinfolds and several parameters of the carbohydrate metabolism in women, but not in men. IR in women was possitively associated with skinfolds, SBP and lipid parameters and beta cell function with VLDL-C. Adult relatives of Type 2 diabetic venezuelan patients from hispanic origin had, early in their lives, several parameters of the metabolic syndrome as hyperinsulinemia, obesity, dyslipidemia and high blood pressure. These alterations were more prominent in women, group in which the association among BMI, WHR and IR were statistically significant respect to SBP, DBP, basal insulin, insulin/glucose ratio, TG and HDL-C.
Assuntos
Diabetes Mellitus Tipo 2/genética , Saúde da Família , Hiperinsulinismo/genética , Resistência à Insulina/genética , Estado Pré-Diabético/genética , Adulto , Idade de Início , Antropometria , Glicemia/análise , Metabolismo dos Carboidratos , HDL-Colesterol/sangue , Comorbidade , Diabetes Mellitus Tipo 2/metabolismo , Feminino , Predisposição Genética para Doença , Teste de Tolerância a Glucose , Humanos , Hiperinsulinismo/epidemiologia , Hiperinsulinismo/etnologia , Hipertensão/epidemiologia , Hipertensão/etnologia , Hipertensão/genética , Hipertrigliceridemia/epidemiologia , Hipertrigliceridemia/etnologia , Hipertrigliceridemia/genética , Incidência , Insulina/sangue , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/metabolismo , Masculino , Pessoa de Meia-Idade , Obesidade/epidemiologia , Obesidade/etnologia , Obesidade/genética , Estado Pré-Diabético/epidemiologia , Estado Pré-Diabético/etnologia , Fatores de Risco , Fatores Sexuais , Espanha/etnologia , Venezuela/epidemiologiaRESUMO
This study reports a 7-y-old boy with severe hypertriglyceridaemia who was successfully treated for 6 y with a low glycaemic index-high carbohydrate modified-lipid diet that produced beneficial changes in triglyceride and total cholesterol levels. It is suggested that a selection of a complex digestible carbohydrate and an adequate ratio between polyunsaturated and monounsaturated fat may, in the long term, favourably improve the lipid profile.
Assuntos
Carboidratos da Dieta/uso terapêutico , Hipertrigliceridemia/dietoterapia , Criança , Dieta Aterogênica , Dieta com Restrição de Gorduras , Humanos , Hipertrigliceridemia/diagnóstico , Hipertrigliceridemia/fisiopatologia , Masculino , Triglicerídeos/sangueRESUMO
With the purpose of exploring the glucose and insulin responses to a breakfast composed of a complex carbohydrate (CC) in the form of a "arepa" prepared with precooked corn flour, with or without the addition of protein and fat (CC + P + F), we studied 6 healthy volunteers, ages ranging from 26-50 years and body mass index of 24.5 +/- 1.32. Three tests were performed on each individual: 1) 75 g OGTT, 2) Ingestion of 75 g of CC ("arepa") and 3) Ingestion of 75 g of CC + 6.7 g protein (low fat cheese) and 4 g fat (margarine). Glycemic values (glucose - oxidase method) and insulinemia (radioimmunoassay) were determined at basal, 30, 60, 120, 180 and 240 min. Glucose (GA) and insulin (IA) areas, glycemic index (GI) and insulin/glucose ratio (I/G) were calculated. We found that the "arepa" has a high GI (71.5%) that it is increased, although not significatively to 140% with the addition of protein and fat. Total GA as well as IA obtained for CC and for CC + P + F were similar to OGTT, however the profiles of the glucose and insulin responses during CC and CC + P + F were less abrupt but more prolonged, resulting in a greater I/G ratio for OGTT in comparison with CC or CC + P + F during the initial steps. We conclude that GI of this corn bread ("arepa") is high in comparison to other complex carbohydrates and it is not altered by the addition of protein and fat. This is possibly due to glucose and insulin responses similar to that produced by OGTT.
Assuntos
Glicemia , Culinária , Carboidratos da Dieta/administração & dosagem , Glucose/administração & dosagem , Insulina/sangue , Zea mays , Adulto , Gorduras na Dieta/administração & dosagem , Proteínas Alimentares/administração & dosagem , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Insulin resistant states are characterized by receptor and post-receptor defects in insulin action. When the insulin resistant state progresses, elevated levels of insulin are accompanied by increasing levels of glucose. In a previous paper we demonstrated that treatment of isolated adipocytes with high levels of insulin led to a decrease in insulin binding as well as a decrease in basal and insulin-stimulated lipid synthesis. The results of the present study establish that the addition of high concentrations of glucose in combination with a high level of insulin, does not modify the decrease in binding of insulin to its receptor. However, the decrease in lipid synthesis previously observed in the presence of high concentrations of insulin was completely overcome by the presence of high glucose.
Assuntos
Adipócitos/metabolismo , Glucose/farmacologia , Insulina/farmacologia , Lipídeos/biossíntese , Adipócitos/efeitos dos fármacos , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Glucosefosfato Desidrogenase/metabolismo , Cinética , Malato Desidrogenase/metabolismo , Complexos Multienzimáticos/metabolismo , Oxo-Ácido-Liases/metabolismo , RatosRESUMO
The purpose of this study was to evaluate the presence of insulin-resistance in non-obese, non-diabetic patients with mild to moderate essential arterial hypertension of recent diagnosis and without prior pharmacological treatment and its relationship with the lipid alteration found in those patients. Twenty-one controls (9 M/12F) and twenty-nine patients (19 M/10 F) were studied. The control group presented mean age: 29 +/- 1.5 years, BMI: 23.9 +/- 0.46 Kg/m2, SBP: 112.6 +/- 2.9 mm Hg, DBP: 68.0 +/- 2.9 mm Hg. The patient group presented mean age: 35 +/- 1.4 years, BMI: 27.3 +/- 0.45 Kg/m2, SBP: 140 +/- 26 mm Hg, DBP: 95.1 +/- 1.4 mm Hg. The fasting levels of glucose, insulin and lipids were measured in each individual. Both controls and patients were subjected to an oral glucose tolerance test (OGTT) with determination of glucose and insulin at 30, 60, and 120 minutes. The patients had significantly (p < 0.05) increased plasma glucose at 0, 30, 60 and 120 min. and increased (p < 0.05) plasma insulin levels at O and 120 min compared to controls. The G/I ratio was significantly lower (p < 0.005) in the hypertensive group, at 0 h and 120 min. Abnormalities in fasting lipid profile were also observed in the patients including a significant increase in TG, Cholesterol, VLDL-C and LDL-C. These increases were especially evident in men and those with higher BMI. There was a positive and significant association between basal-insulin and TG, VLDL-C and DBP in hypertensive patients. We conclude that hyperinsulinemia is present in the majority of hypertensive patients and that hyperinsulinemia is associated with lipid abnormalities specially in men and the most individuals with higher BMI.
Assuntos
Hiperinsulinismo/etiologia , Hipertensão/sangue , Resistência à Insulina , Lipídeos/sangue , Adulto , Glicemia/análise , Índice de Massa Corporal , Feminino , Teste de Tolerância a Glucose , Humanos , Hiperlipidemias/etiologia , Hipertensão/complicações , Masculino , Fatores SexuaisRESUMO
To assess the effect of insulin on lipid synthesis in isolated rat adipocytes, cells were preincubated for 3 h with high concentrations (16.6 nM) of the hormone and lipogenesis measured through 14C-acetate incorporation into lipids, analyzing at the same time the activity of some lipogenic enzymes. It was found that insulin induced not only a decrease in the number of insulin receptors but a 30% loss in basal and insulin-stimulated acetate incorporation into total lipids as well as a decrease in the activities of enzymes related to the novo fatty acid synthesis pathway as malic enzyme and glucose-6-phosphate dehydrogenase.
Assuntos
Tecido Adiposo/metabolismo , Insulina/farmacologia , Lipídeos/biossíntese , Acetatos/metabolismo , Tecido Adiposo/efeitos dos fármacos , Animais , Radioisótopos de Carbono , Células Cultivadas , DNA/metabolismo , Glucosefosfato Desidrogenase/metabolismo , Cinética , Malato Desidrogenase/metabolismo , Masculino , Complexos Multienzimáticos/metabolismo , Oxo-Ácido-Liases/metabolismo , Ratos , Ratos Sprague-Dawley , Receptor de Insulina/efeitos dos fármacos , Receptor de Insulina/metabolismoRESUMO
The prevalences of Entamoeba histolytica and other intestinal parasites were assessed in a suburban community of Maracaibo, Venezuela, by examination of a stool specimen from each of 342 individuals, using iron-haematoxylin stained faecal smears and formalin-ether concentration. The overall parasitic infection rate was 80.4%, and 65.8% of the population had multiple infections. The overall amoebic infection rate, which was highest in female adults, averaged 39.7%. The E. histolytica infection rate was 8.7% and most of those infected were passing cysts. Entamoeba polecki was observed in two samples. Amongst the protozoa, Entamoeba coli was observed most frequently (24.8%) and Giardia lamblia was the predominant pathogen (13.0%). Trichuris trichiura (71.9%) and Ascaris lumbricoides (54%) were the most common parasites, particularly in school-children. The high rates of parasitic and multiple infections reflect the low socio-economic status of the community studied.
Assuntos
Disenteria Amebiana/epidemiologia , Entamoeba histolytica/isolamento & purificação , Adolescente , Adulto , Fatores Etários , Animais , Ascaris lumbricoides/isolamento & purificação , Criança , Fezes/parasitologia , Feminino , Giardia lamblia/isolamento & purificação , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Fatores Socioeconômicos , Trichuris/isolamento & purificação , Venezuela/epidemiologiaRESUMO
Phosphofructokinases from granulocytes isolated from insulin-resistant patients, mainly those from type II diabetics where the degree of insulin resistance was more pronounced, exhibit some changes in their kinetic behavior when assayed under allosteric conditions, characterized by an increased affinity for fructose-6-phosphate, being more resistant to ATP inhibition while it became more sensitive to citrate inhibitory effect. Those changes are suggestive of a isozymic modification to a more L-type enriched enzyme with a loss of the F-type component, probably present in the normal granulocyte.
Assuntos
Granulócitos/enzimologia , Resistência à Insulina , Fosfofrutoquinase-1/metabolismo , Trifosfato de Adenosina/metabolismo , Adulto , Regulação Alostérica , Citratos/farmacologia , Diabetes Mellitus Tipo 1/enzimologia , Frutosefosfatos/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Cinética , Obesidade/enzimologia , Fosfofrutoquinase-1/antagonistas & inibidoresRESUMO
This study was designed to investigate serum levels of iron, ferritin, vitamin B12 and folic acid in 18 Huntington's disease patients and 86 healthy control subjects. Serum iron, vitamin B12 and folic acid levels were normal. Ferritin concentrations were significantly diminished in the choreic patients. The importance of this finding in our attempt to understand the underlying biochemical defect and the chemical nature of the iron deposits found in several brain nuclei in Huntington's disease patients is unknown.
Assuntos
Ferritinas/deficiência , Doença de Huntington/sangue , Adolescente , Adulto , Feminino , Ferritinas/sangue , Hemoglobinas/análise , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Phosphofructokinase from human polymorphonuclear leukocytes has low cooperativity and high affinity for its substrate, F-6-P. It is resistant to ATP inhibition at pH 8; however, at pH 7.1 it becomes sensitive to the effect of this compound. It is activated by F-1, 6-P2; it is not very sensitive to citrate inhibition and F-2, 6-P2 has no effect on its activity. With these kinetic characteristics we assume that perhaps the predominant L-type subunit is accompanied by an F-type component.
Assuntos
Neutrófilos/enzimologia , Fosfofrutoquinase-1/sangue , Citratos/farmacologia , Ativação Enzimática , Frutosedifosfatos/farmacologia , Humanos , Técnicas In Vitro , Cinética , Fosfofrutoquinase-1/antagonistas & inibidores , Valores de ReferênciaRESUMO
With the purpose of knowing which metabolic disorders and clinical complications are more frequently developed by diabetic patients, and to analyze the relationship between the hyperglycemia state and appearance of these complications, we studied a group of patients from a Metabolic Diseases Clinic in Maracaibo, Venezuela. Fifty-four Type II diabetics patients were evaluated by means of: physical examination, anthropometric measurements, biochemical control of glycemia, insulin and lipid pattern, as well as evaluation of the complications presented. The sample consisted of 33 men and 21 women, 75% of which had glycemic values over 140 mg/dl. Basal insulin values were significantly high (29.9 +/- 8.3 uU/ml in men and 30.9 +/- 10.1 uU/ml in women) in relation to a control group (14.5 +/- 2.4 uU/ml), concluding that our diabetics presented basal hyperinsulinemia and insulin resistance. The lipid pattern of the subjects studied showed hypertriglyceridemia (70%) and hypercholesterolemia (67%). A positive association between glycemia and triglycerides values was found in the total group. HDL-cholesterol values were significantly lower in relation to the control group, obtaining a negative correlation between HDL-cholesterol and triglycerides. The clinical complications observed in these diabetics were: non-specific visuals alterations, signs of arterial illness and sensorial disorders distributed in a similar percentage (63, 61 and 51%, respectively). When the independence test X2 was applied, we obtained association (p less than 0.05) between glycemia and the frequency of complications.
Assuntos
Glicemia/análise , Diabetes Mellitus Tipo 2/sangue , Adulto , Idoso , Diabetes Mellitus Tipo 2/complicações , Angiopatias Diabéticas/epidemiologia , Angiopatias Diabéticas/etiologia , Neuropatias Diabéticas/epidemiologia , Neuropatias Diabéticas/etiologia , Feminino , Humanos , Insulina/sangue , Resistência à Insulina , Lipídeos/sangue , Masculino , Pessoa de Meia-IdadeRESUMO
A nutritional survey and evaluation was made in Huntington disease patients by the 24-h-recall method. Control subjects and choreic patients consumed a diet that supplied all the essential amino acids. The diet was hypocaloric, rich in animal protein, and low in fat and carbohydrates. The ratio of calcium to phosphorus in the groups studied was less than 1. High vitamin A and low vitamin C and niacin intakes were observed in Huntington disease patients. Only 17% of control subjects showed weight deficiency; 55% of the patients at stages III and IV of the disease were malnourished despite receiving the same food intake as controls. Although iron intake was deficient in all groups studied, it was enough to maintain normal serum levels of this metal. The deficiencies found in some nutrients do not explain the clinical manifestations observed in Huntington disease patients.
Assuntos
Dieta , Doença de Huntington/metabolismo , Inquéritos Nutricionais , Adolescente , Adulto , Antropometria , Ingestão de Energia , Feminino , Humanos , Doença de Huntington/complicações , Doença de Huntington/genética , Masculino , Pessoa de Meia-Idade , Distúrbios Nutricionais/complicações , Necessidades Nutricionais , Estado NutricionalRESUMO
In order to find if the metabolic disorders more frequently found in our obese population were similar to the ones reported in the literature for other countries, a study was conducted in a group of 34 obese subjects (10 men and 24 women) whose only apparent alteration was a body mass index above 30 (mean value: 36.8 +/- 4.6) to obtain the relation between anthropometric measurements (Quetelet index, skinfold measures and waist/hip ratio) and plasma levels of nine biochemical parameters (including lipids, lipoproteins and glucose and insulin levels after an oral glucose load). The results revealed a tendency to the android distribution of fat in the female population, a significantly elevated triglyceride and total lipids levels and a decreased in HDL-cholesterol in both sexes. Hypercholesterolemia was present mainly in the male population. The most frequent dyslipidemia was Type IV (23%) followed by type IIb (15%). Practically none of the subjects had abnormal glycemic values after the glucose load, however the insulin levels were highly elevated in 80% of the patients, resulting in a great insulin/glucose ratios. Correlation analysis showed no association of the BMI with any biochemical parameter; only the insulin area was positively associated with anthropometric measures (mainly waist/hip ratio) and with the most altered biochemical parameter, the triglycerides. Variance analysis showed that only low HDL-cholesterol values were significantly different in patients presenting high blood pressure and familiar history of diabetes.