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R Luna

Publications and source records attributed to R Luna.

36 records · Page 2Linked to original sources
PubMed1997

Enhanced apoptosis in the thymus of transgenic mice expressing constitutively activated forms of human Rac2GTPase.

Rac proteins constitute a subgroup of the Rho family of small GTPases and include Rac1, which is expressed ubiquitously, and Rac2, a highly homologous protein only expressed in myelo-monocytic and lymphoid cell lineages. In fibroblasts, Rac1 plays a crucial role in control of actin cytoskeleton organisation, cell growth and Ras-induced transformation. In phagocytes, Rac1 and Rac2 regulate a specific enzymatic complex, NADPH oxidase. These multiple functions have been ascribed to Rac proteins only on the basis of cell culture and in vitro biochemical studies. To examine the role of Rac2 in vivo in a T cell lineage, we have expressed either wild-type or constitutively-activated forms of human Rac2 (Rac2V12 and Rac2L61) in transgenic mice under control of the thymus specific lck proximal promoter. We report here a striking atrophy of the thymus in mice expressing even low levels of either of the activated mutants of Rac2, while expression of Rac2wt has no effect. This phenotype is correlated with a marked decrease in the number of double positive (CD4+ CD8+) and single positive (CD4+ CD8- and CD8+ CD4-) thymocytes. Cellular and molecular analyses demonstrate that this defect is due to an increase in apoptosis among thymocytes. As Rac2 is normally expressed in thymocytes and activated T cells, we propose that Rac2 dependent pathways could play an important role in control of growth and death of T cells.

Animals↗
PubMed1997

Comparative study of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) level and IGF-I/IGFBP-3 ratio measurements and their relationship with an index of clinical activity in the management of patients with acromegaly.

To evaluate the utility of measuring the serum insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) level and the IGF-I/IGFBP-3 ratio in the management of acromegalic patients, we comparatively studied the basal concentration of the aforementioned parameters with determination of plasma IGF-I levels and an index of clinical activity of acromegaly in 16 newly diagnosed acromegalic patients (aged 34 to 64 years) before and after hypophysectomy. After adenomectomy, 10 patients remained with "active" disease and six were "cured." Twenty-nine healthy sex- and age-matched volunteers were also studied. Comparison of individual values between untreated acromegalic patients and control subjects showed that none of the patients had overlapping values for IGF-I, whereas five of 16 and three of 16 patients had overlapping values for serum IGFBP-3 and IGF-I/IGFBP-3 ratio, respectively. When we compared the study parameters between the patients who remained with active disease after adenomectomy and the controls, two of 10 had overlapping values for IGF-I, but six of 10 and five of 10 had overlapping values for serum IGFBP-3 and IGF-I/IGFBP-3 ratio, respectively. Moreover, comparison of these parameters between cured and active patients after hypophysectomy showed that none had overlapping values for IGF-I, whereas three of six and one of six had overlapping values for serum IGFBP-3 and IGF-I/IGFBP-3 ratio, respectively. All biochemical variables studied showed significant relationships with an index of clinical activity of disease. In conclusion, our results seem to indicate that among determinations of plasma IGF-I, serum IGFBP-3, and the ratio IGF-I/IGFBP-3 in the evaluation of acromegalic patients, measurement of the plasma IGF-I level has the most discriminative value in the management of these patients.

Acromegaly↗
PubMed1996

Structure of the dehydrin tas14 gene of tomato and its developmental and environmental regulation in transgenic tobacco.

We have isolated a genomic clone encoding tomato TAS14, a dehydrin that accumulates in response to mannitol, NaCl or abscisic acid (ABA) treatment. A fragment of tas14 gene containing the region from -2591 to +162 fused to beta-glucuronidase gene drives ABA- and osmotic stress-induced GUS expression in transgenic tobacco. Histochemical analysis of salt-, mannitol- and ABA-treated plants showed GUS activity mainly localized to vascular tissues, outer cortex and adventitious root meristems, coinciding with the previously observed distribution of TAS14 protein in salt-stressed tomato plants. In addition, GUS activity was also observed in guard cells, trichomes and leaf axils. Developmentally regulated gus expression was studied in unstressed plants and found to occur not only in embryos, but also in flowers and pollen. Tas14 expression in floral organs was confirmed by northern blots of tomato flowers.

Abscisic Acid↗
PubMed1993

Protein intake during aggressive calorie restriction in obesity determines growth hormone response to growth hormone-releasing hormone after weight loss.

OBJECTIVE: We evaluated the influence of two types of calorie restriction, total fast or very low calorie diet, on GH responsiveness to GHRH in severely obese patients. DESIGN: Twenty patients with massive obesity underwent one of two types of calorie restriction, total fast (10 patients) or very low calorie diet (10 patients). MEASUREMENTS: Fasting GH, IGF-I, glucose, insulin and GH secretion after GHRH (100 ug i.v.) were assessed in all patients before and after diet therapy. RESULTS: Both types of diet produced similar weight reduction (total fast, 5.6 +/- 1.6 kg/m2 vs very low calorie diet, 5.6 +/- 1.5 kg/m2 mean +/- SD). A significant increase in the integrated GH secretion was observed after weight loss with very low calorie diet (17 +/- 9 vs 27 +/- 12 mU/l min; P < 0.05). However, no change was found in GH response after weight loss with total fast (13 +/- 5 vs 15 +/- 7 mU/l min). Glucose, insulin and IGF-I levels showed a significant decrease with weight reduction which was similar for both groups. CONCLUSION: These findings suggest that the type of dietary manipulation during calorie restriction in obese patients may influence the changes in GH response to GHRH after weight loss.

Adult↗
PubMed1992

[Association between post-initial remission and HLA phenotype in Type I diabetics].

Our goal was to estimate the occurrence rate of the post-initial remission and its relation with HLA phenotype in type I diabetics (DMI). We studied 50 type I diabetics, 22 women and 28 men, with an average age at the onset of the disease to 15.8 +/- years (range 3-30 years). All patients were conventionally treated with insulin therapy, diet and regular exercise. Six (12%) of the diabetics presented a complete remission during 57.3 +/- 46 weeks, whereas fifteen (30%) patients presented partial remission during 20.1 +/- weeks. No significant differences were observed with regard to age at the onset of the disease, sex, BMI, initial ketoacidosis and stage of gonadal development between those diabetics presenting remission and those who did not presented so. We observed a higher incidence of the HLA-DR4 antigen among diabetics with remission (complete and partial, 61.9%), compared with patients without remission (20%, p less than 0.5). In conclusion, our results support the findings suggesting the presence of a clinical-immunological heterogenicity in DMI, genetically determined and linked to the HLA system.

Adolescent↗
PubMed1990

[Diabetes and pregnancy. Our experience in pregnancy diabetes (1977-1988)].

The records of 303 females with gestational diabetes (GD) seen from 1977 to 1988 in the Hospital La Paz in Madrid were reviewed. In some respects, two periods were separately considered, period A from 1977 to 1983 and period B from 1983 to 1988, the latter corresponding to the activity of the Diabetes and Pregnancy Unit. Significant differences in fetal mortality (0.65%) with nondiabetic pregnant women or between periods A and B were not found. Macrosomic fetuses (the most common abnormality, 18.5%) were related with maternal age, a macrosomic fetus in previous pregnancies, degree of carbohydrate intolerance at the time of diagnosis of the diabetes and need for insulin therapy. This latter feature indicates a more severe degree of metabolic involvement. Regarding risk factors, the most common were older maternal age, family history of diabetes and obesity. The pancreatic reserve in nonobese women with GD (2.1 +/- 0.8 ng/ml) was lower than in obese women with GD (3.3 +/- 0.9 ng/l) (p less than 0.001), higher than in progestational diabetic women type II (1.1 +/- 0.7 ng/ml) and type I (0.15 +/- 0.1 ng/ml) (p less than 0.001), and it was not different from that in normal pregnant women (2.15 +/- 0.6 ng/ml). Insulin therapy for the control of diabetes was required in 24.5% of pregnant women. During the period B, termination of pregnancy by means of cesarean section (25.3%) was higher than in normal pregnant women (11.2%) (p less than 0.001). After pregnancy, 13.2% of patients in period A and 39.1% in period B (p less than 0.01) complied with the evaluation of carbohydrate metabolism. Overall, 26.2% had carbohydrate intolerance and 5.9% diabetes mellitus. Although the creation of the Diabetes and Pregnancy Unit has provided a better care and follow-up of the diabetic pregnant women, has not resulted in significant differences in fetal mortality.

Adult↗
PubMed1986

Potential value of digital radiography. Preliminary observations on the use of dual-energy subtraction in the evaluation of pulmonary nodules.

The radiographic demonstration of calcification in a solitary pulmonary nodule renders the possibility of malignancy extremely unlikely, although rare exceptions have been reported. Conventional roentgenograms and tomograms sometimes provide inconclusive evidence although CT can be highly accurate in both identifying and quantifying calcium content. An alternative method is dual-energy subtraction utilizing scanned projection digital radiography. Forty-one patients with solitary (occasionally multiple) pulmonary nodules were examined with the technique, employing second-generation fan-beam equipment: 28 nodules or masses were noncalcified and 13 calcified. Of the former, 20 were pathologically proved, 16 being malignant and 4 benign (2 granulomas, 2 bronchiectasis); in 3 of the remaining 8, a presumptive diagnosis was reasonably certain (1 granuloma, 2 metastases), while in 5 the diagnosis was not made. In 8 of the 13 calcified lesions, the diagnosis can reasonably be regarded as confirmed as granulomas; 5 are being followed up with that presumptive diagnosis.

Adult↗
PubMed1986

[The reorientation of medical education].

The article is based on the prospective analysis approach to medical education. The instrument of analysis is a questionnaire on the medical education process and on the professional training institution, in which a series of indicators can be used that are grouped in four categories: context, structure, function, and integration. The article concludes with an enumeration of the basic principles to be borne in mind in planning, and with a scheme for the organization of a medical school suitable for attaining the goal of health for all.

Education, Medical↗
PubMed1985

Malignant melanoma presenting as a mass obstructing the common bile duct.

Pathologic and computed tomographic correlation of an obstructing common bile duct mass, found to be malignant melanoma, is presented. No tumour was demonstrated elsewhere. Such a pattern of presentation has not previously been described in this condition. Malignant melanoma, even in the absence of disease elsewhere, should be considered in the differential diagnosis of such lesions seen on computed tomography.

Cholestasis, Intrahepatic↗
PubMed1976

[Seroepidemiologic study of human cysticerosis in the predominantly indigenous rural Indian population of the State of Chiapas].

The overall proportion of sera with antibodies against cyticercus antigens in 3226 serum samples collected among the Indian rural population in the proximity of San Cristóbal de Las Casas, Chiapas, México is 0.49. The proportion of positive sera varied from 0.4 to 7.6% inversely with the number of inhabitants in the community. The global proportion of positive sera in Chiapas being considerably lower than that expected from the autopsy frequency of brain cysticercosis in México City (1.4-3.6%), it is perhaps indicative of different epidemiologic dynamics in rural and urban areas.

Antibodies↗
PubMedDate not supplied

[Neural codes for perception].

OBJECTIVE: This article describes experiments designed to show the neural codes associated with the perception and processing of tactile information. DEVELOPMENT: The results of these experiments have shown the neural activity correlated with tactile perception. The neurones of the primary somatosensory cortex (S1) represent the physical attributes of tactile perception. We found that these representations correlated with tactile perception. By means of intracortical microstimulation we demonstrated the causal relationship between S1 activity and tactile perception. In the motor areas of the frontal lobe is to be found the connection between sensorial and motor representation whilst decisions are being taken. CONCLUSIONS: S1 generates neural representations of the somatosensory stimuli which seen to be sufficient for tactile perception. These neural representations are subsequently processed by central areas to S1 and seem useful in perception, memory and decision making.

Brain↗
PubMedDate not supplied

[Prevalence of type 2 diabetes in the preoperative assessment interview].

OBJECTIVES: To determine the prevalence of type 2 diabetes in preoperative anesthetic assessment interviews during May 2004 and to compare the results to prevalences reported in other studies. PATIENTS AND METHODS: Patients over the age of 20 years who received an assessment interview were included. Type 1 diabetics, pregnant women, and critically ill patients were excluded. We followed the 1997 diagnostic guidelines of the American Diabetes Association. RESULTS: The prevalence of previously diagnosed type 2 diabetes was 10.3%. Three patients were diabetics unaware of their disease. The overall prevalence of type 2 diabetes was 11% in this population. CONCLUSIONS: Type 2 diabetes has a high prevalence among surgical patients in our hospital, higher than that reported for the general population based on other studies.

Adult↗
PubMedDate not supplied

[Our experience in the nutritional treatment of anorexia nervosa (1989-1991)].

The purpose of this study was to assess the evolution in the nutritional situation of patients diagnosed with anorexia nervosa in the Clinical Nutrition Service between January 1 1989 and December 31 1991. Twenty-eight admitted patients (4 men and 24 women) and 38 outpatients (3 men and 35 women) were monitored, with an age of 22.4 +/- 6.4 years and average evolution time of the illness of 3.8 +/- 5 years. Nutritional state was evaluated with anthropometric, biochemical and immunological parameters. Following nutritional therapy, malnutrition and BMI (Body Mass Index) improved significantly over the initial evaluation in all patients, whether admitted or outpatients. All anthropometric parameters improved significantly during the period of treatment of admitted patients, but AMC (arm muscle circumference) rose only in outpatients. An unrestricted diet plus nutritional counselling was the most-used therapeutic procedure in outpatients while most of the admitted patients required dietary supplements. Calorie malnutrition is very common in patients diagnosed with anorexia nervosa: vitamin or trace element deficiencies are very infrequent. Nutritional therapy, suitably coordinated with psychotherapeutic treatment, is effective, enhancing both the nutritional state and anomalous dietary habits.

Adult↗