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Biomedical subjects

G Bravo

Publications and source records attributed to G Bravo.

At least 37 records · Page 2Linked to original sources
PubMed1998

The protective action of amlodipine on cardiac negative inotropism caused by prolonged incubation in vitro.

The mechanism of the antihypertensive action of the 1,4-dihydropyridine Ca2+ antagonist amlodipine was studied in isolated ventricular strips and aortic rings from Wistar rats after oral treatment with amlodipine 15 mg/kg/day for one week. The contractions evoked by electrical stimulation of isolated strips from right ventricles pretreated with amlodipine (5 nM) were unaffected during the first hour after mounting, but they decreased in magnitude after prolonged incubation (4 hr). However, the decrease in response of these preparations after prolonged incubation was less than that observed in strips prepared from untreated rats. A negative inotropic effect of amlodipine was observed at concentrations higher than 300 nM. In the presence of lower concentrations of amlodipine (5 nM-30 nM) after prolonged incubation, the contractions of ventricular strips were significantly more sustained than in the absence of amlodipine. Likewise, the decrease in contractility evoked by increasing the stimulation frequency from 1 to 3 Hz was reduced in amlodipine treated rats. The recovery of contractility was improved when stimulation frequency was returned to 1 Hz. On the other hand, when rat ventricular strips pretreated with amlodipine (5 nM) were exposed to isoprenaline (3 microM), the contractions evoked by isoprenaline were enhanced. The isoprenaline effect was not altered with 300 nM amlodipine, but with 3 microM became weak and was significantly lower than in strips treated with isoprenaline alone. In addition, treatment with amlodipine produced a marked decrease in the contractions evoked by 100 mM KCl solution in isolated aortic rings when compared to untreated rats. This inhibition was produced in a time-dependent manner with an IC50 equal to 30 and 3 nM after 2 and 45 min of contraction, respectively. Ex vivo results show that amlodipine treatment decreased aortic contractility without producing a negative inotropic effect although there was an occupation of cardiac Ca2+ channels. These results suggest that a protective effect of amlodipine on cardiac negative inotropism is produced by prolonged incubation in vitro.

Amlodipine↗
PubMed1998

Combining studies using effect sizes and quality scores: application to bone loss in postmenopausal women.

This article presents a random effects model that uses effect sizes (ES) and quality scores to integrate results from investigations. An empirical example is given with data obtained from a meta-analysis on the effectiveness of physical activity in the prevention of bone loss in healthy postmenopausal women. A Medline search was performed to locate relevant studies published in French or English between January 1966 and May 1996. Three independent reviewers extracted data from studies. Effect sizes were calculated according to the method of Hedges and Olkin. A modified version of Chalmers' scale was utilized to calculate quality scores. DerSimonian and Laird's method with incorporation of the quality scores was used to estimate the overall effect size. Quality scores and the inverse of the variances were included as weights when combining studies. The overall estimate and standard error (SE) of the effect of physical activity on spinal bone mineral density loss in healthy postmenopausal women was ESoverall = 0.4263 (1.1361). When compared to other meta-analysis methods such as the fixed effects model and the model of DerSimonian and Laird without the quality score (DL), the new model generated comparable estimators (fixed effects model's ESoverall (SE) = 1.2724 (0.0139), DLs ESoverall (SE) = 0.3958 (1.2370)). Due to the heterogeneity that existed between studies, a random effects model was more appropriate then a fixed effects model. However, it resulted in wider confidence intervals, as expected. It was shown empirically that the model using quality scores generated narrower confidence intervals than the model of DL alone. The inclusion of covariates such as quality scores in meta-analyses permits the quantification of the variation between studies.

Analysis of Variance↗
PubMed1998

Effects of the type of meniscal lesion on knee function.

The relationship between the type of meniscal lesion (bucket-handle, flap or degenerative tears) and preoperative knee function (5.1 +/- 6.2 days before arthroscopic meniscectomy) was studied in 35 patients. Patients with bucket-handle tears (group B, n = 12) had large knee extension work deficits during maximal voluntary contractions at 30 degrees and 180 degrees/s (Kin-Com dynamometer). These work deficits were accompanied by proportional decreases in the prime mover or agonist-EMG levels (VM: vastus medialis and/or VL: vastus lateralis). These patients had smaller deficits during flexion movements at 30 degrees/s. Moreover, a larger number of negative clinical signs and symptoms (pain at rest and during tests, locking, thigh atrophy, extension and flexion movement deficits larger than 10 degrees) were found with an equal or a higher prevalence in group B than in the other groups. Patients with flap tears (group F, n = 15) had deficits in work and agonist-EMG activity (VM and VL) only during the extension tests. In contrast, patients with degenerative tears (group D, n = 8) had a work deficit and a concomitant decrease in the EMG level of the medial gastrocnemius (MG), only during the flexion test at 30 degrees/s. Comparable mean knee function scores, as measured by the Lysholm and Gillquist questionnaire [35], were obtained for the three groups of patients, suggesting that this measure was not sensitive enough to discern functional differences related to types of meniscal tears. The results of this study have demonstrated a link between the type of meniscal lesion and the consequent preoperative knee joint disability profile as defined by comparison with the sound leg. These results emphasize the need to consider meniscal lesion type and an individual's preoperative strength deficit when group comparisons of patients are made or the effects of therapy (arthroscopic surgery and rehabilitation) are evaluated.

Adult↗
PubMed1998

Comparison of cross-sectional and longitudinal designs in the study of aging of upper extremity performance.

The purpose of the study was to compare two research designs, namely the cross-sectional design and the longitudinal design, in the context of upper extremity performance and age-related changes. Upper extremity performance of 360 randomly recruited healthy, community-dwelling elderly persons was evaluated with reliable and valid sensori-motor tests. Three years later, survivors (n = 264) were reevaluated with the same tests. In many tests, cross-sectional and longitudinal designs were comparable for estimating the changes in upper extremity performance with age. However, in some tests, the decline with age using a cross-sectional design was underestimated. The upper extremity performance decline observed with the longitudinal design was larger than the decline predicted with the cross-sectional design. The withdrawal and survivor biases related to the longitudinal design and the cohort bias associated with the cross-sectional design may, in part, explain these results.

Aged↗
PubMed1998

Pituitary tumors and gamma knife surgery. Clinical experience with more than two years of follow-up.

30 patients with pituitary tumors were treated in our unit and followed for 26-45 months. 14 patients had nonsecreting adenomas, 7 had acromegaly, 5 had prolactinomas, 3 had Cushing's disease. One patient had a choristoma of the pituitary stalk. The patient with a choristoma, 7 patients with nonsecreting adenomas, 4 with acromegaly, 1 prolactinoma and 3 with Cushing's disease had been operated by transsphenoidal microsurgery prior to Gamma Knife (GK) treatment. From this group, one patient with a nonsecreting adenoma and two with acromegaly had undergone fractional external radiotherapy after surgery. Stereotactic MRI localization had been used in all cases. All the tumors showed either a reduction in volume or cessation of growth; 85% of the patients with acromegaly showed normalization of growth hormone (GH) levels. Normalization of ACTH levels occurred in the 3 patients with Cushing's disease. All the patients with prolactinomas showed reduction of prolactin levels but normalization did not occur. However, in 3 cases the bromocriptine could be withdrawn. Deterioration of vision was not observed. One patient suffered transient paresis of the third cranial nerve that improved with steroids. Panhypopituitarism appeared in one case of Cushing's disease two years after the treatment. In the remaining cases there were no changes in their previous physiological pituitary function. We conclude that GK radiosurgery in pituitary tumors is an effective alternative to transsphenoidal microsurgery when compression of surrounding structures does not exist, and it can efficiently replace conventional irradiation.

Acromegaly↗
PubMed1998

WWW accessible system for national/regional registries of clinical results of cord blood transplants: a tool to facilitate cooperative clinical research.

A system, accessible via internet, has been developed to support the Spanish Registry of Cord Blood Transplants (RETSCU). The system includes a database of clinical results directly accessible by transplant centers (TCs) and cord blood banks (CBBs) (restricted to own cases regarding primary data and unrestricted regarding statistics derived from validated data) and gives open access to Web pages containing results approved for publication. It also includes internal mail for two-way and broadcast messages. Patients' data are essentially those included in Eurocord forms. Additional features of the system are: confidentiality; inalterability of validated primary data; identifiability of data sources. The Unix central computer is accessible via the WWW. For security, data transmission is encrypted and passwords are required for access. Copies are regularly updated. Data can be loaded from CBBs and TCs. The procedure for creating and updating records is user-friendly, with the possibility of errors being minimized by extensive automated checks. Validation of patients' records by a manager is required before making data available for general statistical analysis. TCs and CBBs may retrieve data on their own cases, regardless of validation, as individual records or in tables directly transferable to common statistical programs. Statistical analysis may be done on validated data from all the patients in the Registry or from groups selected according to HLA compatibility and disease, type of transplant (related/unrelated), or protocol. Several similarly designed and managed national/regional Registries might be networked and their data integrated into a multinational Registry. Our system would require some additional developments to be used in this way.

Hematopoietic Stem Cell Transplantation↗
PubMed1997

Age- and education-specific reference values for the Mini-Mental and modified Mini-Mental State Examinations derived from a non-demented elderly population.

MAIN OBJECTIVE: To report age- and education-specific reference values for the Mini-Mental State Examination (MMSE) and Modified Mini-Mental State (3MS) Examination. DESIGN: Cross-sectional study. SETTING: Community and institutional settings in five regions across Canada. PARTICIPANTS: 7754 subjects aged 65 and over randomly chosen to take part in the Canadian Study of Health and Aging. Subjects classified as cognitively impaired or demented following a clinical and neuropsychological examination were excluded. MEASUREMENTS: Total scores on the MMSE and 3MS, and the degree to which they are influenced by the age, sex, education, mother tongue and living environment of the subject. RESULTS: Reference values on the two tests are reported through various descriptive statistics for five age groups and four education levels. These values decrease with age and increase with years of schooling. Test scores are also influenced by the subject's sex and mother tongue, albeit to a lesser extent. These observations led to the development of predictive equations of the performance to be expected from a 'normal' elderly subject, given his/her socio-demographic characteristics. CONCLUSION: The use of the reference values and related predictive equations will allow the clinician to interpret a patient's performance on two widely used cognitive tests, in light of the value expected from a group of 'normal' subjects with the same sociodemographic profile.

Age Factors↗
PubMed1997

Meta-analysis of the effectiveness of physical activity for the prevention of bone loss in postmenopausal women.

A meta-analysis was done to measure the effect of physical activity on the bone mass of healthy postmenopausal women. All studies published between 1966 and 1996, in French or English, were reviewed for inclusion from Medline search, bibliographies of relevant studies, review articles and books. Studies had to be prospective intervention trials, randomized or not, evaluating the effectiveness of an exercise program of any duration, frequency and intensity, with a control group. Studies had to measure bone parameters and involve healthy postmenopausal women over 50 years of age who were free of symptomatic osteoporosis at the time of study entry. Effect sizes (ES) were calculated for each bone parameter and site measured in every eligible study according to Hedges and Olkin. DerSimonian and Laird's model was used to estimate overall effect sizes when combining studies. All analyses were bone parameter and site specific. Of 217 papers extracted from the literature, 187 did not meet eligibility criteria and 12 others were rejected. The two main reasons for rejection were that both genders were combined in the analyses and no exercise group without drug interaction was present. Eighteen studies were included for meta-analysis. Taking into account the frequency, duration, compliance rate and average age of the subjects, the programs were judged of moderate intensity and focused on walking, running, physical conditioning and aerobics. A significant effect of physical activity was detected on the bone mineral density at the L2-4 level of the lumbar column in studies published after 1991 (ES = 0.8745, p < 0.05). No effect could be seen, however, on forearm and femoral bone mass. Although applied to a small number of studies, this meta-analysis suggests that exercise programs in a population of postmenopausal women over 50 years of age are effective for preventing spinal bone mineral density loss at the L2-4 level. However, such programs do not have any effect on the forearm or femoral bone mass.

Aged↗
PubMed1997

A weight-bearing, water-based exercise program for osteopenic women: its impact on bone, functional fitness, and well-being.

OBJECTIVE: To evaluate the effects of a weight-bearing, water-based, exercise program designed for women with low bone mass. DESIGN: A test-retest cross-sectional, prospective study. SETTING: Community-dwelling women from a Canadian city. PARTICIPANTS: Seventy-seven postmenopausal women, 50 to 70 years of age, with spinal or femoral bone density below the fracture threshold. INTERVENTION: Subjects exercised in a pool with waist-high water for 60 minutes, 3 days a week, over a 12-month period. Forty minutes of each session were devoted to successive jumps and muscular exercises designed to promote bone accretion, strength, and endurance. MAIN OUTCOME MEASURES: Spinal and femoral bone mineral density (BMD) measured by dual-energy X-ray absorptiometry, functional fitness (flexibility, coordination, agility, strength/endurance, and cardiorespiratory endurance) assessed with the American Alliance for Health, Physical Education, Recreation and Dance battery, and psychological states evaluated with Dupuy's General Well-Being Schedule. RESULTS: Spinal BMD decreased significantly (p < .001), whereas there was no change in femoral neck BMD (p = .90). Four of the parameters chosen to assess functional fitness, namely, flexibility, agility, strength/endurance, and cardiorespiratory endurance, were affected positively by the exercise program (all p values < .001). Psychological well-being also improved significantly after participation in the exercise program (p < .001). CONCLUSION: The intervention was successful in improving the functional fitness and psychological well-being of the participants, despite a lack of effect on the skeletal system. Future studies are needed to identify water exercises that are safe yet exert enough stress on the bones to initiate a bone response.

Aged↗
PubMed1997

Reliability of the Modified Mini-Mental State Examination in the context of a two-phase community prevalence study.

Data collected through the Canadian Study of Health and Aging were analyzed to estimate the reliability of the Modified Mini-Mental State (3MS) Examination when used in the context of a two-phase community prevalence study. During the screening phase of the study, subjects were tested in their home by a lay interviewer, either in English or French. All subjects scoring 77 or under on the 3MS and a sub-sample of those scoring over 77 were reassessed by a nurse during a clinical examination, following which subjects were classified as normal, cognitively impaired but not demented, or demented. Results indicate substantial reproducibility of the 3MS, slightly higher than that of the Mini-Mental State Examination from which it is derived. The english versions of these tests appear slightly more reproducible than their French counterparts.

Aged↗
PubMed1997

Long-term improvement in patients with severe Parkinson's disease after implantation of fetal ventral mesencephalic tissue in a cavity of the caudate nucleus: 5-year follow up in 10 patients. Clinica Puerta de Hierro Neural Transplantation Group.

Different groups worldwide have observed in recent years that stereotactic implantation of fetal tissue can ameliorate the clinical symptoms of Parkinson's disease. The authors therefore investigated whether implantation of fetal ventral mesencephalic (FVM) tissue via open surgery is also capable of producing an improvement and whether this improvement is transient or long lasting. The authors report their findings in a 5-year follow-up study in 10 patients with Hoehn and Yahr Grade IV or V Parkinson's disease in whom a single FVM graft was implanted in a cavity created in the right caudate nucleus. The results indicate that the implants improved motor function and that clinical recovery persisted in seven of the 10 patients 5 years after implantation. Amelioration was observed in both the on and off phases and was accompanied by a 64% reduction in the levodopa dose and withdrawal of the dopamine agonist. The on phase was prolonged from 39% of the waking day to 72%, with reduced intensity and duration of dyskinesias. All symptoms that were analyzed showed improvement, although they differed in intensity and time of onset. The course of improvement seemed to be stepwise, with significant improvement between 5 and 7 months postimplantation followed by two waves of progress peaking in Months 15 and 36. Withdrawal of cyclosporine in three patients after more than 2 years of administration produced a decline in the patients' clinical conditions. In conclusion, the results indicate that open surgery implantation of FVM tissue in the caudate nucleus improves the clinical condition of parkinsonian patients and that this improvement can persist for at least 5 years. In comparison with two earlier series reported by the authors, which involved implants of perfused adrenal medulla and coimplantation of adrenal medulla and peripheral nerve, the course and pattern of improvement in these implant recipients suggests that their recovery can be attributed to more than one factor.

Aged↗
PubMed1996

Clinical experience with cotransplantation of peripheral nerve and adrenal medulla in patients with Parkinson's disease.

Coimplants of adrenal medulla (AM) and peripheral nerve (PN) in animal models of Parkinson's disease (PD) have shown that AM cells survive longer, tend to show neuronal phenotype, and enhance sprouting of host fibers. Since 1987, our implants of perfused AM and fetal ventral mesencephalon (FVM) in PD patients have achieved varying degrees of clinical improvement. If the donor tissue determines the improvement, different types of implants should result in qualitatively and quantitatively different degrees of improvement. The purpose of this study is to determine whether or not the clinical course, improvement slope, and reduction of medication observed in PD patients who undergo tissue transplantation (Tx) depend on the donor tissue type. In a pilot study, four grade IV-V PD patients received implants of precoincubated autologous AM and intercostal nerve in the caudate nucleus (open surgery). Clinical assessment was based on international scales (UPD) as reported for Tx of FVM and perfused AM. There were no systemic or neurologic complications. Four years post-Tx, longer On phases and improved PD symptoms (ADL and motor-UPD) in On and Off persist in four cases, with reduced dyskinesias. Progress appears to be stepwise, starting within weeks of Tx (similar to AM and sooner than our FVM implants), followed by a period of stability and, after a second wave of improvement 12-18 months post-Tx (similar to FVM implants), continues to date. L-dopa medication has been reduced by more than 60% and dopamine agonist use has not resumed. We conclude that our recipients continue to be clinically better than prior to Tx. The course of recovery after co-Tx of AM and PN differs from that of FVM or AM implants. This fact may be related to the etiological factors that produce the improvement.

Adrenal Medulla↗
PubMed1996

Refusal and information bias associated with postal questionnaires and face-to-face interviews in very elderly subjects.

Our objectives were (1) to analyze the refusal bias associated with postal questionnaires and face-to-face interviews and (2) to compare responses elicited from a postal questionnaire with those provided by a face-to-face interview in subjects over 75 years of age. Our methods included a postal questionnaire sent to a representative sample of community-dwelling elderly individuals (n = 842). All subjects were also invited to participate in an in-home interview conducted by a trained nurse. One hundred and six subjects (12.6%) were nonrespondents to the postal questionnaire. These nonrespondents were more cognitively impaired, more disabled, and showed a higher 1-year mortality rate (13.2 versus 5.2%) than respondents. Late respondents who needed a reminder letter were similar to nonrespondents. One hundred and eighty-seven subjects (22.2%) refused to participate in the home interview. These nonparticipants were similar to the participants on age, sex, 1-year mortality rate, and responses given to all but two postal questions. Comparison of postal questionnaire responses and face-to-face responses revealed that agreement was substantial to moderate for factual information (kappa = 0.41 to 0.80) but poor for clinical information (depression, cognitive impairment, disability). A short index including age, sex, and six questions on disability was useful in identifying disabled subjects by a postal questionnaire. Our conclusion is that nonresponse bias is evidenced when postal questionnaires are utilized in the very elderly population and caution should be used when interpreting health data obtained by this technique. Refusal bias from face-to-face interviewing is less important in this population.

Activities of Daily Living↗
PubMed1996

Predictive validity of a postal questionnaire for screening community-dwelling elderly individuals at risk of functional decline.

Screening elderly individuals who are at risk of functional decline in the community is essential in order to implement effective programmes of assessment and surveillance in a context of secondary prevention. The postal questionnaire technique consists of sending a simple questionnaire to all elderly individuals living in a defined area in order to identify those who are at risk. The objective of this study was to develop a postal questionnaire and to test its capacity to predict functional decline in community-dwelling elderly people. A 21-item postal questionnaire was sent with a birthday card to a representative sample of community-dwelling individuals over the age of 75 years (n = 842). One month after sending the questionnaire, all subjects were contacted by a nurse for an in-home interview (n = 655) that included assessment of functional autonomy. One year later, the subjects (n = 607) were reassessed by the same nurse. Of the eligible subjects, 87.4% returned the postal questionnaire. During the year following the completion of the postal questionnaire, 43 subjects died, 13 were institutionalized and 109 had experienced a significant decrease on the autonomy scale, for a total annual occurrence of functional decline of 27.2%. Age and 14 of the 21 items of the questionnaire were associated with a significant relative risk of functional decline. The relative risk associated with not responding to the questionnaire was 2.1. A stepwise logistic regression analysis showed that six items were independent predictors of functional decline. This 6-item Sherbrooke Postal Questionnaire identifies as positive 56% of the population with 75% sensitivity and 52% specificity. We conclude that a postal questionnaire is a feasible and valid technique for screening elderly individuals at risk for functional decline.

Activities of Daily Living↗
PubMed1996

Development and validation of an evaluation instrument for medical students in tutorials.

PURPOSE: To develop and explore the validity of the Tutotest, the first standardized instrument designed to assess the skills and attitudes of medical students working in tutorials in a problem-based learning curriculum. METHOD: The Tutotest, consisting of 44 items rated on a four-point Likert-type scale, was developed from well-defined theoretical frameworks after consultation with students and teachers at the Université de Sherbrooke Faculty of Medicine. In 1988-89, 40 tutors were asked to use the Tutotest to evaluate a total of 100 students at the end of each of the four units of the first-year curriculum. Data were analyzed to examine the homogeneity and reliability of the instrument, explore its factorial structure, and document its correlation with students' grades. RESULTS: A total of 28 tutors (70%) conducted Tutotest evaluations; of a possible 400 evaluations, 270 (67.5%) were returned with complete data. Exploratory factor analysis revealed that the Tutotest was structured around four factors that accounted for 82% of the variance: effectiveness in the group (23 items), communication and leadership skills (13 items), scientific curiosity (four items), and respect for colleagues (four items). The Tutotest had a Cronbach's alpha coefficient of .98 and a split-half coefficient of .98. The intraclass correlation coefficient was estimated to be .46 and would reach up to .81 after averaging five Tutotest evaluations. Tutotest scores showed good correlation (r = .64) with the official tutor's global evaluation and a moderate correlation (r = .39) with students' written examination results. CONCLUSION: The Tutotest was found to be a standardized reliable and valid instrument that can significantly improve the evaluation of students' skills and attitudes during tutorials. Although lengthier than the usual tutor evaluation form, the Tutotest is a good compromise between an unreliable short global scale and a more comprehensive but impractical instrument.

Academic Medical Centers↗
PubMed1996

Hand sensibility of healthy older people.

OBJECTIVE: To develop normative data for four hand sensibility modalities in older subjects. DESIGN: Cross-sectional. SETTING AND PARTICIPANTS: Three hundred and sixty community-dwelling subjects of both sexes, aged 60 to 94, randomly selected from the electoral list of the city of Sherbrooke, Quebec, Canada. MEASUREMENTS: Touch/pressure threshold (Semmes-Weinstein monofilaments), static and moving two-point discrimination (Mackinnon-Dellon Disk-Criminator), tactile recognition (Modified Pick-up test), and thumb kinesthesia. RESULTS: A reduction with age was found in the performance of the study subjects, with the exception of the kinesthesia test. The values obtained in this study are clearly lower than the norms proposed for adults, underlining the importance of using reference values developed for the target clientele. CONCLUSION: The norms will help clinicians to differentiate better between normal and pathological changes in sensibility with age.

Aged↗