Biomedical subjects

D Ortiz

Publications and source records attributed to D Ortiz.

29 records · Page 2Linked to original sources

PubMed1995

Assessment of cardiovascular risk factors in menopausal Argentinian women.

The cardiovascular risk factor profile was assessed in a population sample consisting of 60 nonmenopausal (control) and 100 menopausal women from different cities in Buenos Aires Province, Argentina. Each subject was individually interviewed and asked to complete a specially designed questionnaire aimed at identifying cardiovascular risk factors. A clinical general and gynecological examination including blood pressure and anthropometric measurements as well as a Papanicolaou smear were performed. The most prevalent risk factor in the menopausal group was low physical activity (87% of the subjects), followed by nervous complaints (67%), obesity (64%), familial antecedents of cardiovascular disease (CVD; 38%) and hypertension (33%). Other risk factors assessed showed a level of prevalence below 10%. In the control group, a tobacco smoking habit was the CVD risk factor with the highest prevalence (47%). Nervous complaints also showed a high prevalence (48%). Most menopausal patients (77%) had a cardiovascular risk index (RI) level between 1.5 and 4.0, whereas 17% of these subjects had an RI greater than 4.0 (high-risk patients). The present study reveals that, in the studied community, the menopause is associated with increased levels of both estrogen-dependent and psychosocial risk factors for CVD.

Adult↗

PubMed1994

Effects of stimulus intensity and duration on posterior tibial nerve somatosensory-evoked potential patterns obtained under anesthesia.

STUDY DESIGN: This study analyzed systematic changes in stimulus intensity and duration on the latencies and amplitudes of somatosensory-evoked potential peaks obtained upon posterior tibial nerve stimulation of orthopedic patients under anesthesia. OBJECTIVES: To examine the effects of systematic stimulus changes on somatosensory-evoked potential patterns and to compare the sensitivity of different peaks. SUMMARY OF BACKGROUND DATA: Previous studies primarily examined the effects of either stimulus intensity or stimulus duration but not their interactions. METHODS: Nine orthopedic patients were tested using three stimulus intensities and three stimulus durations. Five peak latencies and four amplitudes were measured. Data consisted of frequency of peak occurrences under each condition and analyses of variances of peak latencies and amplitudes. RESULTS: Three latencies yielded stable findings (P40, N50, P60). Peak latencies under anesthesia were not affected by stimulus intensity or duration. Amplitudes, however, were affected differentially. P40-N50 increased with increases in stimulus intensity or stimulus duration, but no significant interaction effects were found. N50-P60 showed no significant changes associated with stimulus intensity or duration. CONCLUSION: Under combined isoflurane/nitrous oxide anesthesia, somatosensory-evoked potential patterns obtained upon stimulation of the posterior tibial nerves showed no significant changes in major peak latencies with changes in stimulus intensity or duration. However, changes in amplitude were found. Stimulus intensity-duration interaction effects were observed, described, and interpreted.

Adult↗

PubMed1989

Mu1-induced mutant alleles of maize exhibit background-dependent changes in expression and RNA processing.

We have examined effects of mutations created by transposition of the Mu1 element of maize into genes coding for Adh 1 and Sh 1, by means of allozyme measurements, DNA and RNA hybridization, cloning, and sequencing. From our analysis of mutant alleles we conclude that the element acts both to reduce steady-state levels of RNA and to induce aberrant processing of primary transcripts. We also conclude that genetic background can exert considerable influence in determining the degree to which Mu1 affects these aspects of gene expression.

Alleles↗

PubMed1987

Transient correction of genetic defects in cultured animal cells by introduction of functional proteins.

Material was introduced into cultures of cells by using the method of scrape loading, in which cells are simply rubbed from the surface of a plastic tissue culture dish by a rubber-tipped rod in the presence of a macromolecule of interest. The volume of solution introduced into cells was comparable to that generally injected in the direct microinjection method with glass capillaries, that is, about 50 to 100 fl per cell. Genetic defects (lack of hypoxanthine-guanine phosphoribosyltransferase and thymidine kinase) in several cell lines were transiently corrected by scraping the cells in the presence of crude cell extracts prepared from wild-type cells.

Animals↗

PubMed1983

[Patterns of urinary aminoacid excretion in exceptional children and patients with mental disorders in Costa Rica].

The amino acid profile was studied in individual random samples of urine from 1147 normal schoolchildren and 1074 exceptional children: 628 with mental retardation, 332 with hearing and speech defects and 114 with visual defects as well as in 673 patients with mental disorders. Laboratory procedures included chemical tests and one-dimension paper- electro- and column-chromatography. Phenylketonuria was found in a mentally retarded girl and in one of her brothers; iminoglycinuria in a mentally retarded boy and heterozygote cystinuria in a man with manic-depressive psychosis. The percentage of high excretors of beta-aminoisobutyric acid (B-AIB) in the controls (4.88%) was similar to previous findings in the Caucasian race. The children with hearing and speech defects showed a number of high excretors of B-AIB significantly lower (X2 = 5.32; p less than 0.025) and the children with visual defects a number of hyperglycinurias significantly higher (X2 = 9.19; p less than 0.05). Previous non-consistent findings on the excess of high excretors of B-AIB in Down's syndrome were not confirmed in this study. These results suggest a relationship between transport defects in the plasma membrane and pathological disorders in some of the cases screened.

Alanine↗

PubMedDate not supplied

Computer users' postures and associations with workstation characteristics.

This investigation tested the hypotheses that (1) physical workstation dimensions are important determinants of operator posture, (2) specific workstation characteristics systematically affect worker posture, and (3) computer operators assume "neutral" upper limb postures while keying. Operator head, neck, and upper extremity posture and selected workstation dimensions and characteristics were measured among 379 computer users. Operator postures were measured with manual goniometers, workstation characteristics were evaluated by observation, and workstation dimensions by direct measurement. Considerably greater variability in all postures was observed than was expected from application of basic geometric principles to measured workstation dimensions. Few strong correlations were observed between worker posture and workstation physical dimensions; findings suggest that preference is given to keyboard placement with respect to the eyes (r = 0.60 for association between keyboard height and seated elbow height) compared with monitor placement with respect to the eyes (r = 0.18 for association between monitor height and seated eye height). Wrist extension was weakly correlated with keyboard height (r = -0.24) and virtually not at all with keyboard thickness (r = 0.07). Use of a wrist rest was associated with decreased wrist flexion (21.9 versus 25.1 degrees, p < 0.01). Participants who had easily adjustable chairs had essentially the same neck and upper limb postures as did those with nonadjustable chairs. Sixty-one percent of computer operators were observed in nonneutral shoulder postures and 41% in nonneutral wrist postures. Findings suggest that (1) workstation dimensions are not strong determinants of at least several neck and upper extremity postures among computer operators, (2) only some workstation characteristics affect posture, and (3) contrary to common recommendations, a large proportion of computer users do not work in so-called neutral postures.

Adult↗

PubMedDate not supplied

Unexpected corneal flattening after laser in situ keratomileusis.

PURPOSE: To perform a statistical study of the variation (flattening) from the surgical radius (sculpted in the corneal stroma) to the final radius of the first surface of the cornea after laser in situ keratomileusis (LASIK) for correction of myopia. METHODS: The study included 387 eyes with myopia or myopic astigmatism that underwent LASIK using the Nidek EC-5000 excimer laser. Mean age was 34 years (range, 19 to 75 yr). Mean myopia was -5.19 D (range, 0 to -19.00 D) and mean astigmatism was -1.22 D (range, 0 to -5.00 D). The flattening coefficient was defined as: (f) = (Rpost-Rs)/Rs where Rpost. was the corneal radius after surgery (topography performed 1 month after surgery) and Rs was the surgical radius sculpted in the stroma. Mean values and standard deviations of the flattening coefficient were calculated for the 387 eyes for four myopic ranges (0 to -3.00 D, -3.00 to -6.00 D, -6.00 to -9.00 D, and more than -9.00 D), and for three astigmatic ranges (0, -0.25 to -2.00 D, and more than -2.00 D). The correlations between the flattening coefficient and several preoperative ocular variables were obtained. RESULTS: A linear combination of quasi-independent ocular variables (age, anterior corneal radius, corneal thickness, sphere and cylinder) was found in order to maximize the correlation with the flattening for every range. Values for the correlations between 0.4 to 0.5 were obtained. CONCLUSION: The flattening phenomenon was characterized by a flattening coefficient (f).

Adult↗

PubMedDate not supplied

Geometric ray tracing analysis of visual acuity after laser in situ keratomileusis.

PURPOSE: Using a geometric ray tracing model, we explain the increase in visual acuity observed in myopic patients after laser in situ keratomileusis (LASIK). METHODS: This study included 37 eyes of 23 patients who underwent LASIK. All patients had myopia and a spectacle-corrected visual acuity of 0.95 or worse. Clinical tests included biometry, corneal topography, pachymetry, and refraction (with and without cycloplegia). Calculations were made by tracing rays through all the refractive surfaces of the eye based on a Le Grand-type theoretical model of the whole eye. RESULTS: Comparison of spectacle-corrected visual acuity of the eye before surgery, the size of the blur circle calculated by ray tracing, and the magnification for the ocular system facilitated a numerical criterion to assess visual acuity by geometric calculation. This criterion was applied to myopic eyes that underwent LASIK, and the maximum increase in spectacle-corrected visual acuity was predicted. An actual increase in visual acuity of approximately 40% of the predicted maximum was observed in patients. CONCLUSIONS: With geometric ray tracing, it was possible not only to obtain an estimate of the visual acuity before LASIK but also to assess the value of the maximum and probable increases in visual acuity after LASIK.

Adult↗

PubMedDate not supplied

[Quality of life and mortality of patients in intensive care. Indices of quality of life].

INTRODUCTION: At present there is no single practical standardized scale for measuring quality of life (QL). Any proposal should include the patient's physical impairment, level of independence, and subjective perception of happiness. We combined three previously published scales to define a quality of life index (QLI) that we propose as a standard quantitative instrument. The applicability and usefulness of QLI for the measurement of the level of deterioration of patients after admission to an intensive care unit (ICU) was examined. We prospectively evaluated QL before patient admission to determine if it influences mortality, as well as long-term changes in the QL and the factors conditioning te deterioration of patients released from the UCI as evaluated by QL indicators. MATERIAL AND METHODS: To calculate QLI, we combined the Karnofsky scale, daily life activities index, and the perception of quality of life scale. The resulting percentage (QLI) was used to evaluate 536 patients after admission to the ICU and 6 and 12 months after release. QLI was compared with the severity of disease (Apache II), probability of death (MPM), diagnostic group, and socioeconomic variables. RESULTS: Using multivariate methods, four significant variables related with mortality were identified: Apache II--MPM, duration of the stay in the unit, age, and QLI. Our analysis of long-term deterioration showed that advanced age, high QLI before admission, and the patient's diagnostic group explained the degree of deterioration. DISCUSSION: QLI was a useful instrument for obtaining a quantitative estimate of the QL of critically ill patients.

APACHE↗

PubMedDate not supplied

S-adenosyl methionine: A connection between nutritional and genetic risk factors for neurodegeneration in Alzheimer's disease.

Clinical manifestation of Alzheimer's disease may depend upon interaction among its risk factors. Apolipoprotein E-deficient mice undergo oxidative damage and cognitive impairment when deprived of folate. We demonstrate herein that these mice were depleted in the methyl donor S-adenosyl methionine (SAM), which inhibited glutathione S-transferase, since this enzyme requires methylation of oxidative species prior to glutathione-dependent reduction. Dietary supplementation with SAM alleviated neuropathology. Since SAM deficiency promotes presenilin-1 overexpression, which increases gamma-secretase expression and Abeta generation, these findings directly link nutritional deficiency and genetic risk factors, and support supplementation with SAM for Alzheimer's therapy.

Adenosine↗

PubMedDate not supplied

[Prone position: postural treatment for patients with adult respiratory distress syndrome. The nurse's point of view].

The prone position is a therapeutic strategy that can be beneficial in the treatment of adult respiratory distress syndrome (ARDS). In order to evaluate the advantages and possible complications associated with this postural change within the context of nursing, we analyzed retrospectively 71 turns carried out in 32 patients who met criteria for ARDS. The patient was turned by a team of 4 or 5 persons following a strict protocol. The PaO2/FIO2 ratio and SatO2 significantly increased in prone position, without any hemodynamic repercussions. No extubation or loss of vascular accesses or drainage tubes occurred. Complications included: facial edema, low-pressure lesions, and regurgitation of enteral nutrition.

Adult↗