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Biomedical subjects

R Luna

Publications and source records attributed to R Luna.

At least 19 recordsLinked to original sources
PubMed2002

The yeast THO complex and mRNA export factors link RNA metabolism with transcription and genome instability.

The THO complex is a multimeric factor containing four polypeptides, Tho2, Hpr1, Mft1 and Thp2. Mutations in any of the genes encoding THO confer impairment of transcription and a transcription-dependent hyper-recombination phenotype, suggesting that THO has a functional role in gene expression. Using an in vivo assay developed to study expression of long and G+C-rich DNA sequences, we have isolated SUB2, a gene involved in mRNA splicing and export, as a multicopy suppressor of the gene expression defect of hpr1 Delta. Further investigation of a putative functional relationship between mRNA metabolism and THO revealed that mRNA export mutants sub2, yra1, mex67 and mtr2 have similar defective transcription and hyper-recombination phenotypes as THO mutants. In addition, THO becomes essential in cells with a defective Mex67 mRNA export er. Finally, we have shown that THO has the ability to associate with RNA and DNA in vitro. These results indicate a functional link between the processes of elongation and metabolism of nascent mRNA mediated by THO and mRNA export proteins, which have important consequences for the maintenance of genome stability.

Biological Transport↗
PubMed2002

One-pass resurfacing with a combined-mode erbium: YAG/CO2 laser system: a study in 102 patients.

BACKGROUND: The CO2 and erbium: YAG (Er: YAG) lasers have been used for skin resurfacing. A recently developed system combines pulsed ablative Er: YAG and continuous wave subablative CO2 wavelengths in one console. OBJECTIVES: To assess the potential benefits of this system. METHODS: The study follows 102 women, skin types I-V, with 26 full face, 48 perioral and 28 periocular resurfacing procedures. The ablative Er: YAG pulse (350 micros, 29 J cm(-2)) is followed immediately by a non-ablative CO2 laser shot (4-6 W, 50 ms) through the same collimated handpiece (3-mm diameter spot), 50% overlapping, repetition rate 10 Hz, giving two-pass equivalence with one single pass. RESULTS: Patients scored the results as very good (n = 67), good (n = 25) and fair (n = 10). Mild but successfully resolved side-effects occurred in only four patients. The 2-month histology showed a good band of new collagen tightening the overlying healthy epidermis. Follow-up periods ranged from 1.5 to 2 years (mean +/- SD 1.76 +/- 0.33). CONCLUSIONS: This device at the above settings offers speedy resurfacing without compromising the quality of the procedure for the patient, and may well satisfy the basic requirements of laser skin resurfacing.

Adult↗
PubMed2002

Probing the cortical neuronal correlates of a sensory discrimination process.

Key to understanding perception is the form of how sensory stimuli are represented in the evoked activity of the brain. Here, we addressed the question of which components of the evoked neuronal activity in the somatosensory cortex represent the stimulus features while trained monkeys discriminated the difference in frequency between two vibrotactile stimuli. We probed whether these cortical neuronal representations are essential to perception. The results show a strong link between the cortical representation of the stimulus and perception.

Action Potentials↗
PubMed2001

Facial rejuvenation with a nonablative 1320 nm Nd:YAG laser: a preliminary clinical and histologic evaluation.

BACKGROUND: Rejuvenation of photoaged skin involves removal of the epidermis and superficial dermis, encouraging the production of new epidermis with collagenesis and remodeling. The facial appearance during healing is unpleasant, and the complication rate is high. OBJECTIVE: We evaluate a Q-switched Nd:YAG laser operating at 1320 nm, with a cryogen delivery system and a skin temperature sensor. The system cools the target skin, followed by the laser impulse which passes through the cooled epidermis into the dermis. METHODS: Ten patients are presented. Two treatments a week were given over 4 weeks, and the patients were seen at 2 and 6 weeks after the final treatment. RESULTS: The histology showed improvement in the condition of the dermis in all 10 patients, but only 2 of the 10 patients expressed satisfaction with the results, despite similar histologic findings. CONCLUSIONS: Careful patient selection is required. Better patient education is necessary to ensure that the patients' expectations are realistic. We should add treatments that will improve the youthful aspect of the epidermis. The system may well help in maintaining the effects of collagen remodeling following traditional ablative resurfacing procedures, but studies are necessary to show this.

Aged↗
PubMed2001

[Precut Vater's papilla. Prospective evaluation of frequency of use, effectiveness, complication and mortality. Cooperative study in the northwest of the province of Buenos Aires].

INTRODUCTION: Precut papillotomy, has been considered a potentially dangerous procedure. In spite of this, numerous national and foreign referral centers have reported good results with the use of this technique that increases the cannulation rate and permits additional therapeutic procedures. OBJECTIVES: We evaluated the procedure in terms of frequency of use, effectiveness, complications and mortality. PATIENT AND METHODS: Between January 1, 1996 and December 31, 1999, 419 ERCP were performed in our centers. We used precut papillotomy in 51 patients. Inclusion criteria for precut papillotomy protocol were: 1 precut papillotomy indication. 1-1 failure to cannulate the papilla, 1-2 appropriate indication, 1-3 Expert endoscopist, 2 complete follow up, 3 informed consent. The experimental design of the study was prospective. When the patients entered into the protocol, they underwent a needle-knife sphincterotomy according to Huibregise's technique. The follow up was done during 30 days, with a clinical examination, laboratory test and ultrasonography all of them weekly, to determine the possible complications according to Cotton's criteria and the mortality. RESULTS: 4-1) Precut frequency: 51 patients (pts.) (12.1%). 4-2) Follow up: 49 pts. (96.1%) fulfilled the weekly controls; 2 pts. (3.9%) did not come for the controls. 4-3) Sex and Age: Women 29 pts. (56.9%). Age 62.5 +/- 1.74 years. Men: 22 pts. (43.1%) Age +/- 3.35 years. 4-4) INDICATIONS: Jaundice, diagnosis and treatment: 44 pts. (86.3%), post-cholecystectomy pain; 4 pts. (7.8%), and idiopathic abdominal pain: 3 pts. (5.9%). 4-5) Effectiveness: First attempt 35 pts. (71.4%), second attempt: 10 pts (20.4%). Definite effectiveness: 45 pts. (98.1%), failure: 4 pts. (8.1%). 4-6) Complementary treatment: in 43 pts. we performed the following procedures: papillotomy and stone extraction: 26 pts. (53%), papillotomy and prosthesis: 9 pts. (18.4%), Prosthesis: 8 pts. (16.3%, only pre-cut papillotomy: 6 pts. (12.2%). 4-7 Final diagnoses: Coledocholithiasis 41 pts. (83.6%); Malignant obstruction of biliary duct: 4 pts. (8.2%), Pancreatic Cancer: 1 pts. (2%); Ampullary Cancer 1 pts. (2%). Oddi sphyncter dysfunction: 1 pts. (2%). 4-8. COMPLICATIONS: Total 9 pts. (18.4%). mild Haemorrhage: 7 pts. (14.4%). Acute pancreatitis: 2 pts. (4%), mild: 1 pts. (2%), severe: 1 pts. (2%) 4-9-Mortality: not recorded. CONCLUSIONS: 5-1 Precut papillotomy is used by us with the same frequency native authors use it, but less than foreign authors. 5-2 Age, sex, indications, complementary treatment and final diagnoses are similar to those repo. 5-3 reported by other authors. 5-3- High rate of follow up. 5-4- High percentage of effectiveness which coincide with consulted studies. Precut papillotomy was the only therapy in 12.2% of the cases. 5-5 Low percentage of complications and, when present, of minor importance coinciding with other authors. 5-6 No mortality. 5-7 In our experience, precut papillotomy was a safe and effective technique to cannulate the papilla.

Ampulla of Vater↗
PubMed2000

Cell cycle regulated expression and phosphorylation of hpttg proto-oncogene product.

We recently isolated a cDNA for hpttg, the human homolog of rat pituitary tumor transforming gene. Now we have analysed the expression of hpttg as a function of cell proliferation. hPTTG protein level is up-regulated in rapidly proliferating cells, is down-regulated in response to serum starvation or cell confluence, and is regulated in a cell cycle-dependent manner, peaking in mitosis. In addition, we show that hPTTG is phosphorylated during mitosis. Immunodepletion and in vitro phosphorylation experiments, together with the use of a specific inhibitor, indicate that Cdc2 is the kinase that phosphorylates hPTTG. These results suggest that hpttg is induced by, and may have a role in, regulatory pathways involved in the control of cell proliferation.

Amino Acid Sequence↗
PubMed1999

High serum leptin levels in children with type 1 diabetes mellitus: contribution of age, BMI, pubertal development and metabolic status.

OBJECTIVE: Children with diabetes mellitus are prone to develop obesity and to experience a delay in onset of the pubertal process. In order to understand the role of leptin in these abnormalities, serum leptin levels were analysed in children with type 1 diabetes mellitus. SUBJECTS: Twenty diabetic girls, 23 diabetic boys and 66 healthy children (selected from a reference population of 706 normal children), age-, sex- and BMI-matched with diabetic patients, were studied. MEASURMENTS: Standing height, weight and BMI were determined in each child. Serum testosterone, oestradiol and leptin were measured by specific radioimmunoassays, and HBA1c by high performance liquid chromatography. RESULTS: Both diabetic girls and boys showed higher leptin levels than the normative healthy population and a group of age-, sex- and BMI-matched normal children. In an age-related analysis, leptin levels in diabetic girls rose from 7.4 +/- 1.2 and 8.1 +/- 2.1 microg/l for the 5-7.99 and 8-10.99 year groups, to 12.6 +/- 2.4 microg/l for the 11-13.99 year group, and to 15.6 +/- 4.0 microg/l in the 14-15.99 year group in parallel with body weight. Leptin concentrations were parallel but higher (P < 0.05) than those of healthy girls. Diabetic boys had lower leptin levels than girls and, in contrast with normal boys, did not show a drop after the 10-year period. Leptin levels were 4.9 +/- 2.2, 3.9 +/- 0.2, 5.5 +/- 0.6 and 5.1 +/- 0.9 microg/l for the 5-7.99, 8-10. 99, 11-13.99 and 14-15.99 year groups, respectively. When divided by pubertal stage, leptin levels in the prepuberty stage of diabetic girls (8.6 +/- 1.0 microg/l) were higher (P < 0.05) than those in the controls (4.1 +/- 0.4 microg/l). In overt puberty girls, leptin was higher (P < 0.05) for diabetic (15.9 +/- 2.9 microg/l) than for healthy girls (9.2 +/- 1.1 microg/l). In prepubertal boys, differences were observed in leptin levels (4.9 +/- 0.5 microg/l for diabetic boys and 3.4 +/- 0.6 microg/l for healthy boys). In the overt puberty stage, diabetic boys showed higher (P < 0.05) levels of leptin (5.2 +/- 0.7 microg/l) than the healthy matched controls (2.1 +/- 0.2 microg/l). A multiple step regression analysis in the diabetic children revealed no associations between leptin and other relevant variables such as glycosylated haemoglobin, daily insulin dose, or years of suffering from the disease. CONCLUSION: Serum leptin levels were higher in diabetic than in healthy children. These differences were not attributable to age, adiposity or stage of pubertal development, and were probably conditioned by the metabolic perturbation intrinsic to the diabetic state, or the chronic hyperinsulinemia.

Adolescent↗
PubMed1999

[Endoesophageal prosthesis as palliative treatment for malignant esophageal stenosis: cooperative study of the Northwest of the Buenos Aires Province].

PURPOSE: To show the experience in rigid prosthesis used as a palliative treatment for malignant++ esophageal stenosis. MATERIAL AND METHOD: From November 1995 to January 1997, 14 patients between 51 and 83 years old, were referred for rigid prosthesis in a prospective way (71.5 = 2.3); 11 of them were men and 3 women. The criteria for including them was: 11 (eleven) patients suffering from esophagus cancer stage IV; 2 (two) patients suffering from stomach cancer with esophageal invasion stage IV and 1 (one) patient with mediastinum metastasis of breast cancer. Wilson-Cook rigid prosthesis was used for all these cases. The insertion technique was "the dilator method". RESULTS: Successful method: 14 (100%). Mortality: Not recorded. Disorders: In 6 (six) patients (42.8%); 3 (three) (21.4%) at an early stage: migrations and 3 (21.4%) at a later stage: 2 (two) tamponade because of food and 1 (one) magration. Time in hospital or clinic: 24 hours (100%). Improvement on Dysphagia: 14 (100%). Following: 13 (92.8%). Survivance: 18-266 days (92 = 83.6). CONCLUSIONS: 1. High percentage of success in prosthesis setting. 2. No mortality. 3. Low percentage of complications and if so, of minor importance. 4. Minimal time in hospital or clinic. 5. Quick and effective dysphagia improvement. 6. Appropriate follow up. 7. Survival similar to other palliative methods, less morbimortality and cost and better life conditions.

Aged↗
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↗