Variation in blood mercury concentrations in brown skuas (Stercorarius antarcticus) is related to trophic ecology but not breeding success or adult body condition.

Mercury is a pervasive environmental contaminant that can negatively impact seabirds. Here, we measure total mercury (THg) concentrations in red blood cells (RBCs) from breeding brown skuas (Stercorarius antarcticus) (n = 49) at Esperanza/Hope Bay, Antarctic Peninsula. The aims of this study were to: (i) analyse RBCs THg concentrations in relation to sex, year and stable isotope values of carbon (δ13C) and nitrogen (δ15N); and (ii) examine correlations between THg, body condition and breeding success. RBC THg concentrations were positively correlated with δ15N, which is a proxy of trophic position, and hence likely reflects the biomagnification process. Levels of Hg contamination differed between our study years, which is likely related to changes in diet and distribution. RBC THg concentrations were not related to body condition or breeding success, suggesting that Hg contamination is currently not a major conservation concern for this population.

Plastic ingestion risk is related to the anthropogenic activity and breeding stage in an Antarctic top predator seabird species.

During the last decades plastic pollution has become a common issue in marine environments. Studies on seabirds have focused on species that ingest plastics mistaken for prey or indirectly through their preferred prey or, on how foraging strategy influences this behaviour. We evaluated plastic ingestion in relation to the proximity of nests to areas with different anthropogenic pressure, breeding status and breeding stage. We analyzed regurgitated pellets (n = 1001) from a seabird, the Brown Skua (Stercorarius antarcticus lonnbergi) at Esperanza/Hope Bay, Antarctic Peninsula. Plastics were found in 9% of pellets, only in breeders from an area with high antropogenic activity. The prevalence of plastic increased during the brooding of chicks stage, when skuas expand their feeding niche. Our results support previous work which demonstrated that seabirds with wider feeding niche show higher loads of plastics. Altogether, this provides insights into the dynamics of plastic transfer within the environment.

Ethylene signaling triggered by low concentrations of ascorbic acid regulates biomass accumulation in Arabidopsis thaliana.

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.

Lean adolescents with increased risk for metabolic syndrome

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.

[Glucose/insulin response to a glucose overload in subjects at risk for type 2 diabetes]. / Respuesta de la Glucosa/insulina a una sobrecarga glucosada en sujetos con riesgo a diabetes tipo 2.

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.

Women relatives of Hispanic patients with type 2 diabetes are more prone to exhibit metabolic disturbances.

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.

Improved triglyceride control with low glycaemic index-high carbohydrate modified-lipid diet in a hypertriglyceridaemic child.

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.

Paracrine stimulation of preadipocyte-enriched cell cultures by mature adipocytes.

We developed a double-chamber system in which to examine the effects of mature adipocytes on the growth and differentiation of preadipocytes and other cells in the adipose tissue. In the present study we found that mature adipocytes from both lean and obese subjects release a factor that stimulates the growth of preadipocyte-enriched and dedifferentiated adipocyte-enriched cell cultures. This growth stimulation was dependent on both time of exposure to mature cells and the number of mature cells in the coculture. Proliferation of the preadipocyte-enriched (n = 4) and dedifferentiated adipocyte-enriched cultures (n = 5) in the presence of mature adipocytes from obese subjects [body mass index (BMI) > 35] was 4.1- and 2.9-fold more (P < 0.05) than that in the presence of adipocytes from lean subjects (BMI < or = 25). There was no difference in the growth of cultures enriched in preadipocytes or dedifferentiated adipocytes from lean or obese subjects in the absence of mature adipocytes. These observations demonstrate that mature adipocytes from obese patients stimulate the growth of preadipocyte-enriched cultures to a greater extent than those from lean individuals.

Viability of fat obtained by syringe suction lipectomy: effects of local anesthesia with lidocaine.

The results of transplantation of free autologous fat obtained by blunt syringe suction lipectomy are unpredictable. We examined if adipose tissue viability is compromised by using syringe suction lipectomy and by infiltration of the tissue with local anesthetics. As reference, we used adipose tissue samples excised during elective surgery. Fat obtained intraoperatively and by lipectomy was digested with collagenase to isolate adipocytes. The mechanical damage associated with sample handling and cell isolation in both procedures was similar and did not exceed 6% of the total cell mass. In addition, cells isolated from intraoperative and lipectomy samples did not differ functionally, responded similarly to insulin stimulation of glucose transport and epinephrine-stimulated lipolysis, and retained the same growth pattern in culture. Since during fat transplantation the graft is exposed to local anesthetics at both the donor and the recipient sites, we reexamined adipocyte function in the presence of lidocaine. Lidocaine potently inhibited glucose transport and lipolysis in adipocytes and their growth in culture. That effect, however, persisted only as long as lidocaine was present; after washing, the cells were able to fully regain their function and growth regardless of whether the exposure was as short as 30 minutes or as long as 10 days. These results indicate that adipose tissue obtained by syringe lipectomy consists of fully viable and functional adipocytes, but local anesthetics may halt their metabolism and growth.

Protein kinase C is increased in the liver of humans and rats with non-insulin-dependent diabetes mellitus: an alteration not due to hyperglycemia.

We tested the hypothesis that liver protein kinase C (PKC) is increased in non-insulin-dependent diabetes mellitus (NIDDM). To this end we examined the distribution of PKC isozymes in liver biopsies from obese individuals with and without NIDDM and in lean controls. PKC isozymes alpha, beta, epsilon and zeta were detected by immunoblotting in both the cytosol and membrane fractions. Isozymes gamma and delta were not detected. There was a significant increase in immunodetectable PKC-alpha (twofold), -epsilon (threefold), and -zeta (twofold) in the membrane fraction isolated from obese subjects with NIDDM compared with the lean controls. In obese subjects without NIDDM, the amount of membrane PKC isozymes was not different from the other two groups. We next sought an animal model where this observation could be studied further. The Zucker diabetic fatty rat offered such a model system. Immunodetectable membrane PKC-alpha, -beta, -epsilon, and -zeta were significantly increased when compared with both the lean and obese controls. The increase in immunodetectable PKC protein correlated with a 40% elevation in the activity of PKC at the membrane. Normalization of circulating glucose in the rat model by either insulin or phlorizin treatment did not result in a reduction in membrane PKC isozyme protein or kinase activity. Further, phlorizin treatment did not improve insulin receptor autophosphorylation nor did the treatment lower liver diacylglycerol. We conclude that liver PKC is increased in NIDDM, a change that is not secondary to hyperglycemia. It is possible that PKC-mediated phosphorylation of some component in the insulin signaling cascade contributes to the insulin resistance observed in NIDDM.

[Glycemic index and insulin response to the ingestion of precooked corn flour in the form of "arepa" in healthy individuals]. / Indice glicémico y respuesta insulínica a la ingestión de harina precocida de maíz en forma de arepa en individuos sanos.

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.

Insulin and lipogenesis in rat adipocytes. II. Effect of high levels of insulin and glucose on lipid synthesis in isolated rat adipocytes.

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.

A new technique for biopsy of human abdominal fat under local anaesthesia with Lidocaine.

The objectives of this study were to develop a new technique to safety, reliably, and in a cosmetically acceptable way, obtain more than 5.0 g of abdominal subcutaneous fat in out-patients, and to investigate whether inhibitory effects of a local anaesthetic on adipose tissue function in vitro are sufficient argument against the use of infiltrative local anaesthesia during fat biopsy to obtain samples for metabolic studies. Measurements were obtained to compare glucose transport and lipolysis response to insulin in adipocytes isolated from subcutaneous abdominal fat obtained: (i) during elective surgery in eight women and four men (BMI 25.8 +/- 3.1 kg/m2); and (ii) from five male and three female out-patients (BMI 25.8 +/- 3.1 kg/m2) by the described novel technique performed under local anaesthesia with Lidocaine. The effects of acute and 11-day exposure to Lidocaine in vitro on adipocyte lipolysis and glucose transport response to insulin, and the growth potential were determined. In vivo exposure of the tissue samples to local anaesthetic by the novel technique had no apparent effect on isolated adipocyte responses to insulin by stimulation of glucose transport or by inhibitor- or adrenaline-stimulated lipolysis; the results were not different to those for adipocytes isolated from fat obtained during elective abdominal surgeries. Lidocaine added in vitro potently inhibited glucose transport and lipolysis in adipocytes, and cell attachment and growth in primary 'ceiling' culture; this effect persisted only as long as Lidocaine was present. After washing, adipocytes fully regained their function and growth regardless of the exposure period, as short as 30 min or as long as 11 days.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hyperinsulinism and lipid changes in the early stages of essential arterial hypertension]. / Hiperinsulinemia y alteraciones lipídicas en etapas tempranas de la hipertensión arterial esencial.

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.

Insulin and lipogenesis in rat adipocytes. I. Effect of insulin incubation on lipid synthesis by isolated rat adipocytes.

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.

Prevalence of Entamoeba histolytica and other intestinal parasites in a community from Maracaibo, Venezuela.

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.

Kinetics of phosphofructokinase from granulocytes isolated from patients with insulin resistance.

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.

Serum ferritin deficiency in Huntington's disease patients.

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.

Kinetic studies of human polymorphonuclear leukocyte phosphofructokinase.

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.

[Metabolic changes and most frequent complications in a group of type II diabetics. Their relation to the hyperglycemic state]. / Alteraciones metabólicas y complicaciones clínicas más frecuentes en un grupo de diabéticos tipo II. Su relación con el estado de hiperglicemia.

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.