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Biomedical subjects

G López

Publications and source records attributed to G López.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Incidence of insulin-dependent diabetes mellitus in Santiago, Chile (1990-1993)].

The aim of this study was to determine IDDM incidence in the Metropolitan Region of Chile, during the period 1990-1993 as part of the Multinational Project for Childhood Diabetes (WHO DIAMOND Project Group). The studied population was 1499.784 inhabitants. All children in whom the diagnosis was made between January 1, 1990 and December 31, 1993 were included. We used a retrospective and prospective search and confirmation method, using as data sources public and private hospitals and medical records of Pediatricians. The Juvenile Diabetes Foundation was used as a secondary data source. All cases had at least two confirmation sources. A total of 176 new cases (90 male) were diagnosed in the study period, with an annual incidence of 2.92/100,000 for females and 2.95 for males. The group of children from 10 to 14 years old had the highest incidence rate (4.9/100,000), specially in women (5.25/100,000). The yearly incidence was 1.31 in 1990, 2.71 in 1991, 2.93 in 1992 and 3.7/1000,000 in 1993. It is concluded that the Metropolitan Region has one of the lowest incidences of IDDM in Latin America, although it increased along the study years.

Adolescent↗
PubMed1996

[Insulin tolerance test. A useful test to determine insulin resistance in obese hyperandrogenic women].

BACKGROUND: Insulin tolerance test is a simple method to measure insulin resistance that has a good correlation with glucose clamp studies. AIM: To use the insulin tolerance test to detect differences in insulin sensitivity between healthy and obese hyperandrogenic women and to correlate its results with those of the minimal model intravenous glucose tolerance test. PATIENTS AND METHODS: Five healthy women aged 27 +/- 7 years old with a body mass index of 21 +/- 2 kg/m2 and six hyperandrogenic women aged 25 +/- 4 years old with a body mass index of 40 +/- 5 kg/m2 were studied after a 10 hours fast. For the insulin tolerance test 0.1 U/kg of crystalline insulin were injected intravenously and blood samples were drawn to measure glucose at -5,0,3,5,10 and 15 min. after the injection. Insulin resistance was calculated using the slope of descending blood glucose levels (SI1). For the intravenous glucose tolerance test, 29 blood glucose samples were obtained after an intravenous injection of 0.3 g glucose/kg followed by an injection of 0.02 U/kg of crystalline insulin. Insulin sensitivity (SI2) was calculated using Bergman's minimal model. RESULTS: Healthy women had a SI1 of 0.58 (range 0.53-0.63) and a SI2 of 7.9 x 10(-4) x min-1/microU/ml (range 4.15-9.11). For hyperandrogenic women were 0.18 (range 0.06-0.29) and 0.9 x 10(-4) x min-1/microU/ml (range 0.46-1.79), respectively. Both methods had a positive correlation coefficient of 0.859 (p < 0.001). CONCLUSIONS: Insulin tolerance test is a good method to measure insulin resistance and has a good correlation with the frequently sampled intravenous glucose tolerance test.

Adult↗
PubMed1995

Autoimmune thyroid disease in primary Sjögren's syndrome.

PURPOSE: To evaluate the prevalence of autoimmune thyroid disease and thyroid dysfunction in patients with primary Sjögren's syndrome. PATIENTS AND METHODS: Thyroid function of 33 patients with primary Sjögren's syndrome was clinically and biochemically evaluated. Thyroid hormones and autoantibodies against thyroid peroxidase, thyroglobulin, and thyroid hormones were measured. RESULTS: Autoimmune thyroid disease and thyroid dysfunction were found in 15 cases (45%): autoimmune thyroiditis in 8 (24%); autoimmune hyperthyroidism in 2 (6%); and reversible iodine-induced hypothyroidism in the remaining 5 (15%). One or more of the evaluated autoantibodies were detected in 8 euthyroid patients (24%). Overall, the prevalence of autoantibodies against thyroid peroxidase, thyroglobulin, thyroxine, and triiodothyronine was 45%, 18%, 42%, and 36%, respectively. CONCLUSIONS: The high prevalence of autoimmune thyroid disease and thyroid dysfunction found in primary Sjögren's syndrome, using sensitive immunologic and thyroid function tests, suggest that both diseases are more frequently associated than it was previously thought, and should be sought clinically and by laboratory tests in all patients with primary Sjögren's syndrome.

Adult↗
PubMed1995

[Genetic predisposition to develop insulin-dependent diabetes mellitus. A population study in Santiago and Temuco, Chile].

Insulin-dependent diabetes mellitus (IDDM) is strongly associated with particular HLA-DQ alpha/beta markers in white population. The heterodimers conformation composed of a DQ alpha chain with an arginine at residue 52 (Arg52) combined to a DQ beta chain lacking an aspartic acid at residue 57 (non Asp57) increase markedly the risk to develop IDDM. To confirm this association, 63 IDDM patients from Santiago de Chile registry, 20 IDDM patients from Temuco registry and 74 unrelated healthy non diabetic control subjects were studied. With polymerase chain reaction (PCR) and sequence specific oligonucleotide probes the individuals were typed for their HLA-DQA1 and DQB1 alleles, their DQA1/DQB1 genotype and heterodimers conformation were compared. In diabetic population both markers Arg52 homocygote and non Asp57 homocygote were markedly increased regard to control subjects (R/R: 0.76 and 0.85 vs 0.33; ND/ND: 0.78 and 0.75 vs 0.50, p < 0.05). A high relative risk (RR) was determined for both homocygote markers in IDDM groups. Arg52 DQ alpha (R)/non Asp57 DQ beta (ND) heterodimers were strongly associated with susceptibility to IDDM. A high RR was observed in patients with four susceptibility DQ heterodimers (RR1: 13.7 in IDDM-Santiago and RR2: 18.6 in IDDM-Temuco, p < 0.00003). The HLA-DQ alpha/beta markers and their risk heterodimers are increased in our diabetic population and could be considered as susceptibility markers to develop IDDM.

Adolescent↗
PubMed1994

Computer-assisted CT-guided stereotactic biopsy and brachytherapy of brain tumors.

From March 1991 to September 1993, 26 patients (aged 4-78 years) with brain tumors (4 glioblastoma multiforme, 10 nonglioblastoma multiforme, 1 mixed oligoastrocytoma, 2 carniopharyngiomas, 2 meningiomas and 7 metastases) were treated with stereotactic techniques at the Centro Internacional de Restauración Neurológica, La Habana, Cuba. A total of 28 stereotactic surgical procedures were performed with no operative mortality; they included biopsies in all cases, 1 stereotactic microsurgical resection and 12 permanent implants of 192Ir, followed by external beam fractionated radiation therapy (40-60 Gy). The present paper shows that the combined use of a stereotactic approach, a comprehensive and reliable stereotactic dosimetric planning system, stereotactic brachytherapy with 192Ir and complementary percutaneous radiation treatment constitutes a promising strategy for brain tumor management.

Adolescent↗
PubMed1994

[HLA and insulin-dependent diabetes mellitus].

The propensity of an individual to develop type I (insulin dependent) diabetes mellitus is directly related to specific HLA class II proteins, specially those from DR and DQ regions. Genetic susceptibility to insulin dependent diabetes arises from a preestablished conformation of alpha and beta chains of DQ and beta chain of DR. Since the classic demonstration by McDevitt and colleagues that DQ beta chain aspartate at position 57 was protective against the development of the disease, many populations have been surveyed to study the association between the incidence Type I diabetes and determined frequencies of DR and DQ haplotypes. The association between these markers and susceptibility to Type I diabetes is well established in caucasians at the present time. However, little information is available for Latin American populations, that share a mixture of european, african and native genes. Our group is studying genetic markers of three Latin American populations (Argentina, Perú and Chile) and their possible association to the different incidence of Type I diabetes mellitus in each country.

Diabetes Mellitus, Type 1↗
PubMed1994

[Effect of chronic blockade of the opiodergic receptor on insulin resistance in a hyperandrogenic woman].

We report a woman with insulin resistance associated with hyperandrogenism and acanthosis nigricans (HAIR-AN syndrome) treated during 30 days with the prolonged action opioid antagonist Naltrexone. During its administration, decreases in basal blood glucose and serum insulin, insulin and glucose response to a glucose load and plasma testosterone were observed. These findings suggest that opioid activity could play a critical role in the physiopathology of hyperinsulinemia in hyperandrogenic women.

Acanthosis Nigricans↗
PubMed1993

[Acute severe hepatic insufficiency caused by carbamazepine].

Acute liver toxicity caused by carbamazepine is a well known though infrequent event. Severe toxicity with hepatocellular insufficiency is even more rare. A case is presented of a patient who suffered of partial epilepsy on treatment with valproate and carbamazepine, who was admitted because of severe acute liver insufficiency attributable to carbamazepine. He had started treatment with the latter drug two weeks earlier, when he developed fever, jaundice, rash and signs of encephalopathy in association with elevation in serum transaminases levels and a decrease in prothrombin index (24%). Discontinuation of both antiepileptic drugs, together with the usual supportive measures, was followed by a complete resolution. Valproate was restarted without complications. Liver biopsy suggested acute hepatitis of drug-related origin. Granulomas or steatosis were not found. The histologic picture together with the relation between carbamazepine administration and the development of hepatotoxicity allow us to dismiss valproate as the possible causal agent of this patient's disease. Therefore, we believe it was an acute hepatocellular failure secondary to carbamazepine.

Carbamazepine↗
PubMed1992

[Reversibility of early stage diabetic nephropathy].

A double blind crossover trial was performed on the effect of enalapril on urinary albumin excretion (UAE) in normotensive insulin dependent diabetics. Nineteen normoalbuminuric (UAE < 30 mg/24 h) and 17 microalbuminuric patients (UAE > 30 and < 300 mg/4 h) were studied; all patients had post prandial blood glucose levels < 180 mg/dl, HbA1 < 11% and none had chronic diabetic complications. Both groups had similar age, years of diabetes, body mass index and protein ingestion (70 g/day). Fifty percent of patients in each group received 5 mg/day of enalapril or placebo during one year, and during the second year the therapy was switched. No changes were observed in blood pressure, post prandial blood glucose, HbA1 and plasma electrolytes during the study period. A reduction in creatinine clearance, within normal limits, in both groups of patients treated with enalapril and no modifications with placebo were observed. UAE decreased significantly in normo and microalbuminuric patients initially treated with enalapril from 19 +/- 8 to 8 +/- 2 and from 71 +/- 19 to 39 +/- 12 mg/24 h respectively. These values increased during the placebo period to 23 +/- 6 and 47 +/- 13 mg/24 h respectively. Among those initially treated with placebo, UAE increased only in normoalbuminurics from 19 +/- 7 to 28 +/- 9 mg/24 h. During subsequent treatment with enalapril, UAE decreased in both groups. It is concluded that, in this group of patients, enalapril decreases UAE, possibly preventing the progression to severe forms of diabetic nephropathy.

Adolescent↗
PubMed1992

[Insulin secretion and sensitivity in patients with secondary failure to oral hypoglycemic drugs].

Secretion and peripheral sensitivity to insulin was investigated in diabetic patients with secondary failure to oral hypoglycemic drugs. 8 patients with secondary failure (non responders), 7 non insulin dependent diabetic patients with good response to oral drugs (responders) and 8 control subjects were studied. Insulin secretion was determined with peptide C in urine obtained 4h after a 500 Cal breakfast; in vivo insulin sensitivity was studied by the euglycemic hyperinsulinemic clamp technique. All groups were comparable in age, nutritional status and duration of diabetes. Non responders had higher fasting blood sugar levels compared to responders (228 +/- 70 vs 136 +/- 21 mg/dl, p < 0.05). Controls had lower blood sugar levels than the other 2 groups (93 +/- 8, p < 0.05). Insulin levels were similar in non responders and responders (24 +/- 12 and 16 +/- 9 uU/ml, respectively) and higher than in controls (10 +/- 3, p < 0.05). Peptide C was lower in non responders than in responders (3.8 +/- 1 vs 5.3 +/- 1.4 nm/4h, respectively, p < 0.04), but similar to controls (4.4 +/- 1.2). No difference in secretion of insulin was noted between non responders and responders. Insulin sensitivity index was 3.67 +/- 1.41 ((mg/kg.min)/(uU/ml)). 100 in non responders and 4.20 +/- 1.14 in responders; the index for controls was 7.92 +/- 1.70 (p < 0.05). These results show that non responders have normal insulin levels, although inappropriate for the level of hyperglycemia. Insulin sensitivity in non responders is similar to responders but lower than controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1991

Effects of dopamine-receptor antagonists and renal denervation on amino acid-induced hyperfiltration.

The mechanism whereby an infusion of amino acids (AA) leads to increments in glomerular filtration rate (GFR) and renal plasma flow (RPF) is incompletely understood. Dopamine (DA) is a catecholamine in which known actions at low doses include the ability to increase both GFR and RPF. Furthermore, urinary DA excretion has been shown to be augmented after an oral protein load. We therefore studied the renal hemodynamic response to intravenous infusion of a 10% mixed AA solution in anesthetized euvolemic Wistar-Furth rats in the presence or absence of specific DA1 [Sch 23390 (SCH)] and DA2 [S-sulpiride (S-SP)] receptor antagonists. Infusion of AA in vehicle-pretreated rats resulted in a 28 +/- 8% increase in GFR and a 29 +/- 6% increase in effective ERPF over baseline values. Administration of AA in the presence of SCH also resulted in elevations in both GFR and ERPF by 23 +/- 3% and 26 +/- 6%, respectively. In contrast, when AA were given in the presence of S-SP, the rise in both GFR and ERPF was completely prevented. To examine whether the AA-induced hyperfiltration was due to DA release from renal nerves or enhanced renal tubule DA synthesis, we administered AA to rats in which the left kidney had been chronically denervated while the right kidney remained intact. Infusion of AA led to significant increments in GFR (33 +/- 4%) and ERPF (34 +/- 7%) only in the intact control kidney, whereas GFR and ERPF remained unaltered in the denervated kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1991

[Incidence of insulin-dependent diabetes mellitus in the metropolitan region].

We used a retrospective search and confirmation method to establish the number of new cases of insulin dependent diabetes mellitus diagnosed between Jan 1, 1986 and Dec 31, 1989 in subjects under 15 years of age in the Metropolitan region of Chile. All hospitals and outpatient facilities of the National Health Service, other hospitals and private offices of endocrinologists and specialists in diabetes were surveyed, as well as the registry from the Juvenile Diabetes Foundation. A total of 115 cases, 52 in males and 63 in females were found, for an annual incidence of 1.69 and 2.15 per 100,000, respectively. Overall, the annual incidence rates were 2.22 in 1986, 1.22 in 1987 (p < 0.001), 2.13 in 1988 and 2.09 in 1989. A greater number of cases was diagnosed at age 4 in males and at age 12 in females (p < 0.001). The greater number of cases were diagnosed from June to August (winter) and the lowest in October (p < 0.001).

Adolescent↗
PubMed1991

[Insulin sensitivity in vivo: evaluation of non insulin dependent diabetes mellitus patients and healthy subjects by euglycemic hyperinsulinemic clamp].

Insulin resistance is commonly found in non insulin dependent diabetic patients. We used the euglycemic hyperinsulinemic clamp method to measure in vivo sensitivity to insulin in 7 non insulin dependent patients responding to oral hypoglycemic agents (Diabetics) and in 8 healthy subjects (Control). Fasting blood sugar was 136 +/- 21 vs 93 +/- 8 mg/dl respectively (p < 0.0002). Basal insulin levels were 16 +/- 9 vs 10 +/- 3 uU/ml, respectively (NS). Sensitivity to insulin was higher in diabetics (4.2 +/- 1.14 (mg/kg/min)/(uU/ml) x 100)) than in controls (7.92 +/- 1.7, p < 0.01). Efficiency in the use of insulin was lower in diabetics (3.20 +/- 0.64 vs 6.50 +/- 1.42 ml/kg/min, p < 0.002). Thus, non insulin dependent diabetics exhibit resistance to insulin. Effective treatment with oral hypoglycemic agents does not normalize insulin sensitivity.

Blood Glucose↗
PubMed1990

[Incidence of gestational diabetes in pregnant women at diabetic risk in Santiago, Chile].

A study conducted from 1982 to 1984 in Santiago, Chile, examined the frequency of gestational diabetes in 580 pregnant women at high risk for diabetes and 100 controls receiving prenatal checkups at a primary care center in the western area of the city. The purpose of the study was to establish recommendations for early detection in developing countries. The risk factors for the disease were studied and their frequency and distribution were calculated in 911 pregnant women in the general population of the area. The diagnosis of gestational diabetes was based on the results of the oral glucose tolerance test. The disease was diagnosed in 13.8% of the pregnant women with risk factors for diabetes and in 1% of the controls. Three risk factors were statistically significant: chronological age (OR = 1.14), nutritional status (OR = 1.01), and basal blood glucose level (OR, 25-36 years = 4.03; OR, greater than 36 years = 4.84). The prevalence of gestational diabetes was 4.27%. It was concluded that the frequency of gestational diabetes is significantly higher in pregnant women at risk for diabetes than in those not at risk. In developing countries it is recommended that testing for the disease be limited to pregnant women over 25 years of age, those who are obese, and those with a fasting blood glucose level above 4.4 mmol/l.

Adult↗
PubMed1990

[Microalbuminuria in insulin-dependent diabetics: the prevention of diabetic nephropathy].

We evaluated the effects of angiotensin converting enzyme inhibition upon the urinary excretion of albumin in 36 insulin dependent normotensive diabetic patients with adequate metabolic control and no evidence of renal failure. 19 subjects had normal levels of albumin excretion (< 30 mg/24 h) and 17 showed microalbuminuria from 30 to 300 mg/24 h. Half of the patients were randomly selected in each group to receive enalapril, 5 mg/day. A progressive decrease in albumin excretion levels was observed for both enalapril treated subgroups, from 18.9 +/- 8.3 to 8.1 +/- 2.7 mg/24 h (normoalbuminurics) and from 73.1 +/- 25.0 to 40.1 +/- 26.3 mg/24 h (microalbuminurics). In contrast, an increase in albumin excretion from 19.4 +/- 6.8 to 29.4 +/- 14.2 mg/24 h was observed in non treated normoalbuminuric patients. Untreated patients with microalbuminuria remained with stable albumin excretion levels (67.4 +/- 39 to 64.8 +/- 23.4 mg/24 h). Enalapril treatment was associated to a significant (p < 0.05) decrease in creatinine clearance which remained within normal limits. Blood pressure, Na and K plasma levels and total proteins remained normal throughout the study. Thus, angiotensin converting enzyme inhibition reduces the urinary excretion of albumin in insulin dependent diabetics with normo or microalbuminuria.

Adolescent↗