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Biomedical subjects

L Ramírez

Publications and source records attributed to L Ramírez.

36 records · Page 2Linked to original sources
PubMed1997

Clinical and magnetic resonance imaging correlation in acute spinal cord injury.

The aim of this study was to correlate traumatic spinal cord injury (SCI) patient's outcome with magnetic resonance imaging (MRI) performed within the first 15 days following trauma. We retrospectively analyzed 55 SCI patients. Upon admission, 28 were diagnosed as having a complete SCI (51%), versus 27 with an incomplete SCI (49%). All of the patients with a normal pattern on MRI (four cases), had an incomplete SCI, whereas all patients (15 cases) presenting with a hemorrhage pattern (Type 1) had a complete SCI (P = 0.0001). Fourteen of the 15 individuals (93.4%) with the edema pattern (Type II) had an incomplete SCI (P = 0.001), while the other patient had neurological deterioration, and a syrinx was noted 2 years later (6.6%). Among the 10 individuals showing a contusion pattern (Type III), seven were admitted with an incomplete SCI (70%) and three with a complete SCI (30%). The compression pattern tends to be associated with a complete SCI in 77.8% (seven of nine patients). All patients with a transection pattern on MRI (two cases) were clinically diagnosed as having a complete SCI. Early functional prognosis may be established on the basis of clinical presentation of SCI and associated MRI. Cord hemorrhage and transection are irreversible, while edema has a potential for neurological recovery. Cord contusion tends to be associated with an incomplete SCI, unlike the compression pattern, in which the prognosis depends on the degree of the initial neurological damage.

Adolescent↗
PubMed1997

[Assessment of the feasibility of a distance medical education program].

BACKGROUND: Continuing medical education is essential to cope with the accelerated evolution of medical knowledge. AIM: To assess the feasibility of a distance medical education program prepared in a written format. SUBJECTS AND METHODS: Ninety physicians, aged 25 to 29 years old and with 1 to 4 years of medical practice, working mostly in rural locations, participated in the program. The sending of 10 issues with medical topics was programmed. The topics were selected according to the results of an survey done among physicians of the region. Each issue contained an evaluation that had to be returned to the authors. RESULTS: Eighty two physicians completed the program and 59 returned the evaluations. The mean obtained score in the cognitive evaluation was 80 +/- 6 points (range 68 to 97 points) of a scale from 0 to 100. The qualitative survey revealed a high degree of approval of the issue's format, contents and evaluation system. The favorable effect on patient's management and on the detection and control of chronic diseases was emphasized. CONCLUSIONS: This distance medical education program had a good receipt and compliance among physicians and contributed to continuing medical training.

Adult↗
PubMed1995

Nasal inflammatory responses in children exposed to a polluted urban atmosphere.

Southwest Metropolitan Mexico City (SWMMC) preadolescent children have been exposed to a highly polluted urban atmosphere most of their lives. The main objective of this study was to determine by nasal lavage (NAL) the acute inflammatory nasal influx elicited in these children upon exposure to three different polluted days. Ozone, the main criteria pollutant for SWMMC, varied both in the number of hours above the National Ambient Air Quality Standard (NAAQS), which is 0.12 ppm as a 1-h maximum concentration not to be exceeded more than once per year, and in the maximal concentrations in the preceding three NAL sampling dates. Nasal neutrophilic influx, the surface expression of the B2 integrin CD11b on the nasal polymorphonuclear leukocytes (PMNs), rhinoscopic findings, respiratory symptoms, and nasal cytologies were evaluated in the 38 exposed children and in the 28 control children living in a nonpolluted Pacific coast port. SWMMC children had an average daily outdoor exposure of 7.7 h and complained of nasal mucus secretion, epistaxis, intermittent nasal obstruction, diurnal cough episodes, and chest discomfort. Nasal mucosal atrophy by rhinoscopy was present in 37/38, and all children had an abnormal nasal cytology. Exposed children had significantly higher nasal PMNs and nasal PMN-CD11b expression than controls. PMN median values in exposed children were higher than controls on all sampling dates (November 12, p < .001; November 17, p < .001; and November 24, p < .00001). Interestingly, a lower nasal neutrophilic response (p < .0004) was recorded in the SWMMC children 18 h after exposure to the highest O3 concentrations (up to 0.307 ppm) and the largest number of hours with O3 > 0.12 ppm (7 h). The question of a competing inflammatory response at the bronchioalveolar level with structural damage is raised. These NAL findings underscore the need to restrict outdoor activity in SWMMC children during the months of greater potential exposure to ozone.

Air Pollutants↗
PubMed1995

[Evaluation of a computer-based independent study program applied to fourth year medical students].

The aim of this work was to assess an independent study program on hypertension using a computer multimedia program developed by the authors. Twenty-four randomly chosen students participated in the program and 76 students that continued to attend to classical lectures were used as controls. At the end of the program, a cognitive test with 40 multiple choice questions and an opinion questionnaire were applied. The experimental group had higher grades in the test than controls (71.4 and 64.6% respectively p < 0.001) and a highly favourable opinion of the program. It is concluded that computer based teaching programs are a useful and feasible alternative to lectures.

Computer-Assisted Instruction↗
PubMed1994

[Results of a problem-based learning experience applied to first year medical students].

The aim of this work was to study the feasibility of applying problem-based learning methodologies to first year medical students. During 1992, they participated in tutorial groups composed by ten students, that undertook the study of three clinical problems from a biological, psychological and social perspective. Cognitive tests that included multiple choice and developmental questions were used for assessment. An anonymous enquiry about the students opinion towards the educational experience was also applied. Students achieved 76% of the predetermined goals for each problem. Scoring was better for developmental than multiple choice questions. The experience had a great acceptance among students, that considered as positive features the learning motivation, the stimulus for active participation, the achievement of personal expectancies, the integration of knowledge areas and the encouragement of team work and information seeking.

Chile↗
PubMed1993

[Ureteroscopy. Our results and complications].

From November, 1987 to December, 1990, 399 cases of ureteral calculi were treated by rigid ureteroscopy (URS). Our success and complication rates are presented. Of these, 99 (25%) had a calculus in the pelvis (78/99), iliac (15/99) or lumbar (6/99) ureter, and 300 (75%) had Sandstrasse in the distal ureter. The cases with Sandstrasse were submitted to ureteroscopy within the first 48-72 hours to remove the ureteral obstruction, prevent hydronephrosis or sepsis and to expedite treatment. If symptomatic, obstructive and/or 7 mm or more in diameter, a nephrostomy tube was placed first whenever there was sepsis [23/300 (7%) of those with Sandstrasse and 3/99 (3%) of those with a ureteral calculus] or marked dilatation of the renal cavities [29/300 (9%) and 6/99 (6%), respectively]. The success rate was 93% for the cases with Sandstrasse versus 85% for those with a ureteral calculus, and the complication rates were 5.7% versus 9%, respectively. The foregoing results confirm the high success rate and scant morbidity of ureteroscopy in the treatment of ureteral calculus and Sandstrasse.

Adolescent↗
PubMed1993

[A urinary outbreak of Acinetobacter baumanii in a spinal cord injury unit].

From January 1990 to April 1992, 114 urinary strains of Acinetobacter baumanii were isolated in 57 patients with traumatic spinal cord [correction of medular] injury. The strains were characterized by having all of them the same biochemical identification, except for citrate, maltose and tryptophan-desaminase. Until December 1990, (5 strains) were resistant to all antibiotics, except to tobramicine, amikacine, cotrimoxazol and imipenem (6.3%, 33.9%, 26.7% and 0% of resistances, respectively); since January 1991, (99 strains) became resistant to all of them, except to imipenem. 39.5% of AB were isolated in pure cultures, 46% of them with pyuria. Between February 1991 and January 1992, we observed the highest number of affected patients, although without seasonal predominance. We observed as well a higher incidence among males (46 males, 11 females). 80% of them carried a permanent probe. Only 6 patients presented clinical signs directly related to AB. The environmental study could not demonstrate any source of contagion or transmission mechanism.

Acinetobacter Infections↗
PubMed1992

Activity of heart and muscle lactate dehydrogenases in all-aqueous systems and in organic solvents with low amounts of water. Effect of guanidine chloride.

The effect of urea and guanidine hydrochloride (GdmCl) on the activity of lactate dehydrogenases from heart and muscle was studied in standard water mixtures and in reverse micelles formed with n-octane, hexanol, cetyltrimethylammonium bromide and water in a concentration that ranged over 2.5-6.0% (by vol.). In all water mixtures GdmCl (0.15-0.75 M) and urea (0.5-3.0 M) inhibited the activity of the enzymes at non-saturating pyruvate concentrations. At concentrations of pyruvate that proved inhibitory for enzyme activity due to the formation of a ternary enzyme-NAD-pyruvate complex, GdmCl and urea increased the activity of the enzymes. This increase correlated with a decrease of the ternary complex, as evidenced by its absorbance at 320-325 nm. In the low-water system it was found that: (a) at all concentrations of pyruvate tested (0.74-30 mM), GdmCl enhanced the activity of the heart enzyme to a similar extent; (b) in the muscle enzyme, GdmCl inhibited or increased the activity through a process that depended on the concentration of pyruvate and GdmCl; (c) under optimal conditions, the activation by GdmCl was about two times lower in the muscle than in the heart enzyme, although in all-water media the activity of the muscle enzyme was twice as high. The expression of lactate dehydrogenase activity in the low-water system was higher with the heart than with the muscle enzyme compared to their activities in all-water media (about 260 and 600 mumol min-1 mg-1 in the heart and muscle enzymes respectively). Apparently for catalysis, the water requirement in the heart enzyme is lower than in the muscle enzyme. It is likely that the different response of the two enzymes to solvent is due to their distinct structural features.

Animals↗
PubMed1992

Enzyme activation by denaturants in organic solvent systems with a low water content.

The effect of urea and guanidine hydrochloride (GdmCl) on the activity of heart lactate dehydrogenase, glycerol-3-phosphate dehydrogenase, hexokinase, inorganic pyrophosphatase, and glyceraldehyde-3-phosphate dehydrogenase was studied in low-water systems. Most of the experiments were made in a system formed with toluene, phospholipids, Triton X-100, and water in a range that varied over 1.0-6.5% (by vol.) [Garza-Ramos, G., Darszon, A., Tuena de Gómez-Puyou, M. & Gómez-Puyou, A. (1990) Biochemistry 29, 751-757]. In such conditions at saturating substrate concentrations, the activity of the enzymes was more than 10 times lower than in all-water media. However the activity of the first four aforementioned enzymes was increased between 4 and 20 times by the denaturants. The most marked activating effect was found with lactate dehydrogenase; with 3.8% (by vol.) water maximal activation was observed with 1.5 M GdmCl (about 20-fold); 4 M urea activated, but to a lower extent. Activation by guanidine thiocyanate was lower than with GdmCl. The activating and inactivating effects of GdmCl on lactate dehydrogenase depended on the amount of water; as the amount of water was increased from 2.0% to 6.0% (by vol.), activation and inactivation took place with progressively lower GdmCl concentrations. When activity was measured as a function of the volume of 1.5 M GdmCl solution, a bell-shaped activation curve was observed. In a low-water system formed with n-octane, hexanol, cetyltrimethylammonium bromide and 3.0% water, a similar activation of lactate dehydrogenase by GdmCl and urea was observed. The water solubility diagrams were modified by GdmCl and urea, and this could reflect on enzyme activity. However, from a comparison of denaturant concentrations on the activity of the enzymes studied, it would seem that, independently of their effect on the characteristics of the low-water systems, denaturants bring about activation through their known mechanism of action on the protein. It is suggested that the effect of denaturants is due to the release of constraints in enzyme catalysis imposed by a low-water environment.

Animals↗
PubMed1989

Mating system in rye: variability in relation to the population and plant density.

The amount of outcrossing was estimated using seven enzyme loci assayed in seven populations of rye (Secale cereale L.). Single-locus outcrossing values fluctuated widely from locus to locus in each population. The weighted mean single-locus estimates ranged from 0.716 to 0.946, and multilocus estimates ranged from 0.701 to 0.910. The analysis showed that self-pollination occurred in the rye populations, and, as a result of selfing, populations contained homozygotes in excess of random mating expectations at the seedling stage of development. Low plant density, which causes low pollen density during fertilization, seems to weaken the self-incompatibility system; at low plant density, the outcrossing estimate was significantly lower than was obtained at high plant density.

Breeding↗
PubMed1989

The use of functional analysis of the ribosome as a tool to determine archaebacterial phylogeny.

Forty different antibiotics with diverse kingdom and functional specificities were used to measure the functional characteristics of the archaebacterial translation apparatus. The resulting inhibitory curves, which are characteristic of the cell-free system analyzed, were transformed into quantitative values that were used to cluster the different archaebacteria analyzed. This cluster resembles the phylogenetic tree generated by 16S rRNA sequence comparisons. These results strongly suggest that functional analysis of an appropriate evolutionary clock, such as the ribosome, is of intrinsic phylogenetic value. More importantly, they indicate that the study of the nexus between genotypic and phenotypic (functional) information may shed considerable light on the evolution of the protein synthetic machinery.

Archaea↗
PubMed1984

[The professional profile of the physician].

This article presents a study done to develop a professional profile of the physician based on the criteria of the medical faculty of the School of Medicine of Concepción University, Chile. It describes the methodology applied in the study and the results obtained organized under five heads: the personal qualities of the physician, professional ethics, professional competence, professional improvement, and the administrative aspects of the physician's work. The article stresses that constructing a professional profile is the most efficient way to organize the entire process of professional training and curriculum evaluation and that, therefore, every university should devise and continually revise the profiles of the professions in which it offers training.

Attitude of Health Personnel↗