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Biomedical subjects

M E Gómez

Publications and source records attributed to M E Gómez.

17 recordsLinked to original sources
PubMed2002

Scaling of the interface roughness in Fe-Cr superlattices: self-affine versus non-self-affine.

We have analyzed kinetic roughening in Fe-Cr superlattices by energy-filtered transmission electron microscopy. The direct access to individual interfaces provides both static and dynamic roughness exponents. We find an anomalous non-self-affine scaling of the interface roughness with a time dependent local roughness at short length scales. While the deposition conditions affect strongly the long-range dynamics, the anomalous short-range exponent remains unchanged. The different short- and long-range dynamics outline the importance of long-range interactions in kinetic roughening.

Journal Article↗
PubMed2001

[Glucose/insulin response to a glucose overload in subjects at risk for type 2 diabetes].

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.

Adult↗
PubMed1999

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.

Adult↗
PubMed1997

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.

Child↗
PubMed1997

[Prevalence of neurocysticercosis in individuals affected by epilepsy].

INTRODUCTION: In this investigations, was carried out a neurocysticercosis (NC) prevalence study during seven months in the Instituto Neurológico de Antioquia with the purpose of known neurocysticercosis frequency as cause of epilepsy in patients older than ten years that we attended in our institute. MATERIAL AND METHODS: Computerized tomographies (CT) were made to 503 patients, with epilepsy, 24.7% of them were CT positive for NC. Cysticercosis enzyme linked immunoelectrotransfer blot (EITB) and enzyme linked immunoabsorbent assay (ELISA) test were made to 178 patients, 19.6% were EITB positive for NC and 5% ELISA positive for NC. Results. From this result it is possible to infer that about 8% of the 503 patients with epilepsy had cysticercosis, according to EITB that is the golden assay for NC. The CT and ELISA test had 94.3% and 27.7% sensitivity, respectively, according to EITB. The specificity of the CT for NC was 49.2% and specificity for ELISA test was 100% as compared to EITB. The multivariate analysis with logistic regression allowed to establish association of positive EITB with factors such as male sex, eating pork, headaches and multiple lesions in CT. CONCLUSIONS: Prevention and education actions are necessary for the interruption of the neurocysticercosis transmission chain in order to diminish the high prevalence of epilepsy in the country and its complication and consequences.

Adult↗
PubMed1996

Isozyme analysis of human polymorphonuclear leukocyte phosphofructokinase from insulin resistant individuals.

Phosphofructokinase (PFK) from human polymorphonuclear leukocytes (PMN) was characterized by immunological titration with subunit specific antibodies and column chromatography on QAE-Sephadex in three different groups: control, type II diabetic, and obese individuals. It was found that PMN phosphofructokinase in the three groups consists mainly of a mixture of L4 and M4 homotetramers with possibly some hybrid forms. The predominant subunit was the L-type. A 24% decrease in the specific activity of the L-type isozyme was observed and an intermediate form (I-isozyme) having 23% of the total activity in diabetic individuals appeared. In obese individuals a 30% decrease was observed in the activity of M-type isozyme and 9% of the total activity corresponded to the intermediate form. Kinetic studies showed different regulatory properties among the isozymes from the three groups. The lower PFK activity found in diabetic and obese individuals can be associated with the decreased activity in the L-type isozyme (for diabetic individuals) and in the M-type isozyme (for obese individuals); the lower activity can also be associated with the four times lower affinity for F-6-P showed by the M-type isozyme, the decreased sensitivity to ATP inhibition (for both isozymes), and the appearance of an intermediate form with a different kinetic behaviour.

Adenosine Triphosphate↗
PubMed1995

Isozyme analysis of human normal polymorphonuclear leukocyte phosphofructokinase.

Phosphofructokinase (PFK) from human polymorphonuclear leukocytes (PMN) was characterized by immunological titration with subunit specific antibodies, column chromatography on QAE-Sephadex and SDS-polyacrylamide gel electrophoresis. Two different isozymes, M-type and L-type, were found. The M(r) values of the M and L subunits were 79,500 +/- 1,914 and 74,250 +/- 1,258, respectively. The two isozymes presented different kinetic and regulatory properties. The results suggest that PFK from human normal PMN is a mixture of M-type and L-type homotetramers, mainly, with possible minor heterotetrameric forms.

Adenosine Triphosphate↗
PubMed1995

Clinical and anatomopathological study of 2000 cryptorchid testes.

OBJECTIVE: To establish whether age at the time of surgery and location of the testes help to determine the anatomopathological lesions. PATIENTS AND METHODS: Between 1972 and 1992 surgery was performed on 2000 testes in 1342 children, 658 of whom had bilateral cryptorchidism. The clinical, surgical and anatomopathological records were reviewed. RESULTS: Parametric and non-parametric tests failed to reveal any relation between the tubular fertility index or tubular diameter and the time of surgery or testicular location. CONCLUSION: We cannot recommend a particular age at which surgery should be performed, in relation to the anatomopathological damage.

Adolescent↗
PubMed1995

[Dyslipidemia and hyperinsulinemia in normoglycemic-obese relatives of patients with non-insulin dependent diabetes mellitus].

To determine the most frequent dyslipidemias among first-degree relatives of NIDDM patients, and its association with their glucose-tolerance status and hyperinsulinemia, we have started to examine members of NIDDM pedigrees, according to American Diabetes Association guidelines for nuclear family studies. In a large family with 2 NIDDM siblings in the 2nd generation, and 4 siblings with NIDDM in the 3rd generation, we have evaluated 14 first degree relatives and also 15 sex and aged matched healthy control subjects without family history of diabetes. The NIDDM relative group presented BMI = 31.8 +/- 3.9 kg/m2, SBP = 128 +/- 18.2 mmHg, DBP = 84 +/- 12.7 mmHg. Both relatives and controls were subjected to a 2h 75g OGTT for glucose and insulin determinations. Although none of NIDDM relatives has IGT, both Glycemic Area (GA) and Insulin Area (IA) were greater (p < 0.01) in the NIDDM relative group. The Insulin/Glucose ratio was also higher (p < 0.01) at 0 and 120 min of OGTT, this might be indirect evidence of Insulin- Resistance. Fasting serum lipids in the NIDDM relatives were TG = 148 +/- 24mg/dl, T-Chol = 244 +/- 10.7mg/dl, HDL-C = 34.2 +/- 2.5mg/dl; lipids in the control group were TG = 84.8 +/- 10.1mg/dl, T-Chol = 167 +/- 10.2mg/dl, HDL-C = 44.4 +/- 2.6mg/dl. Electrophoretic pattern showed type IIa (30.7%) and IIb (61.5%) hyperlipidemias in the NIDDM relatives. In this group, there was a positive and significant association between basal insulin and DBP (r = 0.67; p < 0.01), and between DBP and both TG (r = 0.74; p < 0.01)) and VLDL-C (r = 0.58; p < 0.05). It was also obtained a negative association between basal insulin and HDL-C (r = -0.89; p < 0.001). These data suggest that hyperinsulinemia in association with lipid abnormalities could appear early (before the development of Impaired Glucose Tolerance and Diabetes) in first degree relatives of NIDDM patients.

Adult↗
PubMed1994

[Glycemic index and insulin response to the ingestion of precooked corn flour in the form of "arepa" in healthy individuals].

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.

Adult↗
PubMed1994

[Behavior of Streptococcus mutans under prolonged exposure to xylitol, without reculture].

Previous studies carried out in our laboratory showed that Streptococcus mutans--a cariogenic oral bacteria--did not metabolize an anticariogenic sugar alcohol, xylitol, even after a 10-month adaptative period with monthly transfers to a fresh medium. Due to the potential risk to adaptation observed in bacterias, it was studied the behavior of Streptococcus mutans (Strain 1161, Ingbritt) exposed to the polyol during 7 months, without monthly transfers to a new medium. After 7 months the cells were monthly transferred to a fresh medium for 7 more months. The cells were maintained and grown in a Trypticase-soytone-base medium without dextrose which contained xylitol (0.25 g/100 mL) or no sugar added. The control was represented by cells of Streptococcus mutans growing in Trypticase- soytone-base medium containing dextrose (0.25 g/100 mL). The growth pattern in the presence of xylitol was similar to that obtained in the cultures without sugar added, but it was 63-78% lower when compared with the control. The final pH in the cultures with xylitol was around 6.0; in the control it was very low (4.69 +/- 0.12). When the cells maintained in xylitol were transferred to the medium containing dextrose, the growth pattern was similar to that of the control. Any cultures fermented xylitol; the pH of the fermentation medium remained around 6.00 when the xylitol was present. No uptake of 14C-xylitol was observed and the activity of the enzyme xylitol dehydrogenase could not be detected with the experimental procedure used. The present study confirmed the Streptococcus mutans inability to metabolize xylitol, even after a prolonged adaptative period in the sugar alcohol. Moreover, it demonstrated that xylitol could be considered an inert substance to Streptococcus mutans since the cells were viable in the presence of the xylitol, or in the medium without sugar added.

Bacteriological Techniques↗
PubMed1993

Inhibition of glycolysis by amino acids in ascites tumor cells. Specificity and mechanism.

The effect of glutamine and asparagine on glucose metabolism has been studied in ascites tumor cells. Either of these amino acids decreased the glycolytic flux about 80%. Half-maximal effects were obtained with 0.14 mM glutamine and 0.087 mM asparagine. Among the 20 L-amino acids, only glutamate produced a similar effect. Glutamine and asparagine caused a 70% increase of hexose monophosphates and a large decrease of fructose-1,6-P2 and triose phosphates, evidencing a strong inhibition of the phosphofructokinase (EC 2.7.11) reaction. Analysis of the levels of various phosphofructokinase effectors revealed that fructose-2,6-P2 and AMP decreased 4-fold, phosphoenolpyruvate, citrate, and ATP increased 4-, 3-, and 1.8-fold, respectively, and that there was no change in ADP, Pi, and intracellular pH. Assay of phosphofructokinase at concentrations of substrates and effectors determined to be in the cells showed that the low activity of this enzyme could be accounted for by the change in the concentration of effectors, the major mechanism being the change in adenine nucleotides. The decrease in fructose-2,6-P2 contributed very little to the inhibition of phosphofructokinase activity. The effects of amino acids were prevented by amino-oxyacetate, suggesting that transamination was an obligatory step for these changes.

Amino Acids↗
PubMed1988

Allosteric inhibition of Dictyostelium discoideum fructose-1,6-bisphosphatase by fructose 2,6-bisphosphate.

It has been found that the inhibition of Dictyostelium discoideum fructose-1,6-bisphosphatase by fructose 2,6-P2 greatly diminished when the pH was raised to the range 8.5-9.5, which resulted in a marked decrease of the affinity for the inhibitor with no change in the Km for the substrate. This provides evidence for the involvement of an allosteric site for fructose 2,6-P2. Moreover, the fact that excess substrate inhibition also decreased at the pH values for minimal fructose 2,6-P2 inhibition, and was essentially abolished in the presence of fructose 2,6-P2, strongly suggests that this inhibition takes place by binding of fructose 1,6-P2 as a weak analogue of the physiological effector fructose 2,6-P2.

Allosteric Regulation↗
PubMed1988

Urinary triiodothyronine excretion.

The purpose of this work was to estimate the 24 h urinary excretion of free and conjugated triiodotironine (T3) using a direct radioimmunoassay and enzyme hydrolysis. Mean urinary values of free and total T3 (mean +/- 1 SD) in euthyroid controls were 2074 +/- 673 and 2819 +/- 809 pmol/24 h respectively. In patients with hyperthyroidism, values of free hormone were about 4.2 times higher than the mean value of the euthyroid controls, and about one-third in patients with hypothyroidism. These results show this measurement to be useful as an indicator of thyroid function. Mean renal clearance of free T3 was 211.6 +/- 62.8 ml/min (mean +/- 1 SD) in euthyroid controls, 260.8 +/- 87.5 ml/ml in hyperthyroid patients and 229 +/- 98.7 ml/min in hypothyroid patients. The data show that T3 renal clearance is, in all cases, greater than glomerular filtration rate, suggesting tubular secretion of T3.

Adult↗
PubMed1987

Identification of two forms of 6-phosphofructo-2-kinase in yeast.

Two forms of 6-phosphofructo-2-kinase have been identified in Saccharomyces cerevisiae by their different chromatographic behaviour on CM-Sephadex C-50. One of them was not adsorbed and represented approximately 30% of the eluted activity. The other one emerged at about 120 mM KCl. A molecular mass of 120 kDa was found for both of them. No differences in kinetic behaviour in susceptibility to activation by cAMP-dependent protein kinase were found between the two forms.

Enzyme Activation↗
PubMed1980

Complete proximal tubular acidosis (Type 2, RTA) in chronic active hepatitis.

Fifteen patients with chronic active hepatitis (CAH) were tested in order to ascertain the site of tubular dysfunction in renal tubular acidosis (RTA) associated with CAH. Renal plasma flow and GFR were reduced in the patients compared to controls (P < 0.005). Underbasal and acidification conditions, twelve patients showed normal acid-base balance and net acid excretion, while three patients had basal hyperchloremic metabolic acidosis while passing alkaline urine and showing bicarbonaturia. A sustained acidification test showed adequate urinary acidification in these three patients. Bicarbonate loading carried out in two of the three patients showed a proximal tubular acidifying defect (Type 2 RTA), Distal RTA (Type 1 RTA) complicating CAH is widely known, but these data suggest that CAH can also involve the proximal convoluted tubule in isolation.

Acid-Base Equilibrium↗