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Biomedical subjects

J Jobin

Publications and source records attributed to J Jobin.

52 records · Page 3Linked to original sources
PubMed1985

Clinical evaluation of left ventricular function using the cardiac helical fiber model: an echocardiographic study.

The cardiac helical fiber concept was introduced in 1969 and was shown mathematically to provide better approximations of normal ejection fractions compared with the conventional circumferential fiber model. The clinical applicability of this concept was evaluated noninvasively by M-mode and two-dimensional echocardiography in 55 subjects: 10 with aortic insufficiency, 10 with congestive cardiomyopathy, eight with hypertension, eight who were long-distance runners, 12 who were active and seven who were sedentary normals. Comparison of myocardial shortening by the circumferential and helical fiber models showed that the former discriminated only two groups of subjects, while endocardial and epicardial helical shortening discriminated three and four groups, respectively. Regression analyses suggest that more than 90% (r2 = 0.92) of variation in ejection fraction may be accounted for by variation in endocardial shortening, and that more than 75% (r2 = 0.77) of variation in observed endocardial shortening may be accounted for by variation in epicardial contraction. The study demonstrates that the helical fiber length concept may be useful for the noninvasive evaluation of left ventricular function in man.

Adult↗
PubMed1985

Estimation of regional stress in the left ventricular septum and free wall: an echocardiographic study suggesting a mechanism for asymmetric septal hypertrophy.

Although asymmetric septal hypertrophy is noted in a wide variety of cardiac disorders, its cause remains unclear. One possible mechanism is that the septum is subjected to greater systolic stress because of its flatter (more eccentric) contour. This was investigated noninvasively in nine subjects by estimation of regional myocardial stress from measurements of blood pressure by cuff sphygmomanometry and by echocardiographic examinations of left ventricular shape and dimensions. Analysis of left ventricular cavity shape showed that both the free and septal walls were elliptical, but the septum was more eccentric than the free wall. Using a conceptual model to determine changes in regional systolic stress, the theoretical rate of increase in regional stress relative to pressure (delta S/delta P) was significantly greater in the septum compared to the free wall. Increased hypertrophy of the septum to normalize this increased delta S/delta P may be the cause of asymmetric septal hypertrophy in many disorders associated with elevated left ventricular pressure.

Adolescent↗
PubMed1985

Measurement of glomerular filtration rate in conscious unrestrained rats with inulin infused by implanted osmotic pumps.

A method is described for determining glomerular filtration rate (GFR) in conscious unrestrained rats without extracellular volume expansion. The glomerular marker used was 14C-labeled inulin infused in the minimal fluid volume of 1 microliter/h by intraperitoneally implanted osmotic minipumps. The workability, reproducibility, and precision of the technique was evaluated in sham-operated (sham) and uninephrectomized (UNI-NX) rats for 6 days. In six sham-operated rats the clearance of [14C]-inulin calculated from the plasma value obtained in a blood sample taken at 10 A.M. before food consumption was (means +/- SE): day 1 after pump implantation: 1.38 +/- 0.05; day 2: 1.27 +/- 0.05; day 3: 1.46 +/- 0.16; day 4: 1.45 +/- 0.15; day 5: 1.33 +/- 0.08; day 6: 1.38 +/- 0.11 ml/min. In six UNI-NX rats the corresponding values were: day 1: 0.88 +/- 0.04; day 2: 0.79 +/- 0.05; day 3: 0.91 +/- 0.03; day 4: 0.91 +/- 0.03; day 5: 0.83 +/- 0.06; day 6: 0.87 +/- 0.05 ml/min. When determined on day 2, 3, or 6 at 6 P.M., i.e., at the end of the food consumption period, [14C]inulin clearance was increased in all animals compared with the value determined at 10 A.M. in the fasted state. The use of implanted osmotic minipumps for delivering a glomerular marker such as [14C]inulin allows the determination of GFR in conscious unrestrained rats with normal fluid balance conditions. This method appears to be particularly appropriate for studying the influence of the intake and composition of food on GFR in physiological conditions.

Animals↗
PubMed1985

Familial resemblance in maximal heart rate, blood lactate and aerobic power.

There are considerable interindividual differences in maximal oxygen uptake per kilogram of body weight (VO2 max/kg), maximal heart rate (max HR) and maximal blood lactate (max blood La) measured during a progressive exercise test. The aim of the study was to quantify the familial relationships for these variables. Parents and children of 38 families of French-Canadian descent were submitted to a modified Balke treadmill test. VO2 max/kg and max HR were the highest values reached during the test for 1 min. Max blood La was obtained from a blood sample taken 2 min after the test. The effects of age and sex were significant for max blood La and VO2 max/kg in each generation. Scores were thus adjusted through multiple regression procedures (age + sex + age X sex + age2), yielding residuals which were submitted to further analysis. Intraclass correlations (ri) were significant in pairs of sibs for max blood La and max HR, i.e. 0.28 (p less than 0.01) and 0.43 (p less than 0.05), respectively. For VO2 max/kg, pairs of spouses and sibs were about similarly correlated (ri = 0.20 and 0.15; p less than 0.05). Data suggested that children were more related to their mother than to their father for VO2 max/kg, VO2 max/kg of fat-free weight, and particularly for max HR. It was concluded that familial resemblance and heritability estimates for maximal aerobic power, max HR and max blood La were quite low and generally nonsignificant. Correlations between biological sibs were, however, consistently significant for max HR and max blood La. The suggestion of a maternal effect in maximal aerobic power should be further investigated.

Adolescent↗
PubMed1984

Calcium restriction and parathyroid hormone enhance renal compensatory growth.

Calcium has been shown to control the proliferation of various cells in vitro and in vivo. Despite this information it is not known whether the Ca status or Ca-regulating hormones could modulate the degree of compensatory growth of the remaining kidney after renal mass reduction. In the present work the influence of dietary Ca, parathyroid hormone (PTH), and calcitonin (CT) on renal compensatory growth ( RCG ) was studied in unilaterally nephrectomized (UNI-NX) rats. UNI-NX rats were pair-fed diets with high (1.1%, HCa) or low (0.1% LCa) Ca content for 3, 8, and 15 days. After UNI-NX the wet weight of the remaining kidney increased much more in rats fed LCa than HCa. Values of dry weight, total protein, and DNA content were also significantly higher in the remaining kidney removed from rats fed LCa than from those fed HCa. LCa did not display such effects in sham-operated rats with intact renal mass. The amount of dietary Ca did not influence the progressive rise in glomerular filtration rate (clearance of inulin) of the remaining kidney as assessed 3, 8, and 15 days after UNI-NX. In UNI-NX rats fed LCa chronic administration of CT in doses that induced hypocalcemia did not inhibit the enhanced RCG induced by LCa. In UNI-NX rats fed HCa chronic administration of PTH mimicked the effect of LCa. In conclusion, dietary Ca restriction can markedly enhance the compensatory but not the normal growth of the kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Familial resemblance in catecholamine changes to cold stress and maximal exercise.

Parents and children from 38 families were submitted to a cold-stress and maximal treadmill test. The number of subjects varied depending on the measurements. Plasma epinephrine and norepinephrine, blood pressure and heart rate were measured before, during and after a cold hand immersion test (in a water bath at 5 degrees C for 2 min), as well as before and after maximal exercise (modified Balke). Scores were adjusted for the effects of age and sex through multiple-regression procedures (age + sex + age X sex + age2 + age3), yielding residuals which were submitted to analysis. Characteristic variations during cold stress were observed. Maximal exercise yielded a mean aerobic power of 43 ml/kg min-1 (SD = 10), a mean maximal heart rate of 192 (SD = 10) and a mean maximal blood lactate of 65 mg/100 ml (SD = 23). Family resemblances in cold stress and maximal exercise adaptive reactions were investigated by comparison of between-family over within-family means of squares. In response to the cold stress, there were indications of family lines in induced changes for systolic blood pressure, epinephrine, and total catecholamines at 1 min after the test (p less than or equal to 0.05). Furthermore, parent-child correlations were significant and reached 0.38 for epinephrine, 0.28 for norepinephrine, and 0.34 for total catecholamines. Familial concentrations could not be detected before or 8 min after the cold stress. There are no indications of family resemblance in plasma catecholamine concentrations following exposure to maximal-exercise stress. It is concluded that genetic variation is probably contributing only moderately to catecholamine changes under cold stress and very little under exercise stress.

Adolescent↗
PubMed1982

Neonatal renal vein thrombosis - long-term follow-up after conservative management.

Six patients who had neonatal renal vein thrombosis underwent re-evaluation of renal function 21 months to 12 years after initial diagnosis. Plasma creatinine clearances were normal in all patients as was urinary concentrating ability and urinalysis. Five patients had elevated systolic and diastolic blood pressures. However plasma renin activities were normal. Intravenous pyelography and renal scintigraphy revealed morphologic abnormalities in four patients. This study emphasizes that after apparent full recovery from neonatal renal vein thrombosis, arterial hypertension may persist and warrants careful long-term follow-up.

Adolescent↗
PubMed1981

Influence of different types of physical fatigue on a visual detection task.

The present study was designed to investigate the effects of different types of physical fatigue-past demand for exertion-on the performance of a visual detection task performed with and without masking. 31 male subjects were first administered a VO2 max test and familiarized with the detection task. They were divided into two groups to control potential effects of masking. They were subjected to three experimental treatment involving the utilization of different sources of energy: (a) a short anaerobic alactic acid effort recruiting phosphocreatine, (b) a supramaximal effort (anaerobic lactic acid) recruiting glycogen without oxygen, and (c) a progressive (partially anaerobic) effort recruiting glycogen and oxygen. All three were performed on a treadmill. Blood samples were collected for the anaerobic lactacid and the partially anaerobic exercises. Once fatigued, all subjects undertook the detection task. A 2 X 3 X 2 X 8 analysis of variance, with repeated measures on the last three factors, was applied to the data (mask/no mask X type of exercise X pre-post performance measures X location of the letter to be detected). No significant difference was found for either the main effects or interactions, except for the location of the letter and the mask/no mask condition. It appears therefore that a physically fit population (mean VO2 max = 62.39 ml X kg(-1) X min(-1)) shows no detectable decrement in a perceptual task performed after fatiguing exercises recruiting various types of energy sources.

Adult↗
PubMedDate not supplied

Aerobic exercise and the placebo effect: a controlled study.

An experiment was conducted with 48 healthy young adults engaged in a supervised 10-week exercise program to determine whether a placebo effect is involved within the exercise-psychological enhancement connection. Based on an expectancy modification procedure, one-half of the subjects were led to believe that their program was specifically designed to improve psychological well-being (experimental condition) whereas no such intervention was made with the second half (control condition). Expectations for psychological benefits and aerobic capacity (VO2max) were measured before and after completion of the program. Self-esteem, as the indicator of psychological well-being, was measured on four specific occasions: at the beginning, after the fourth and seventh weeks, and upon completion of the training program. The results showed similar significant increases in fitness levels in both conditions. Moreover, self-esteem was significantly improved over time in the experimental but not in the control condition. These findings provide evidence to support the notion that exercise may enhance psychological well-being via a strong placebo effect. Implications of the results with regard to exercise prescription are discussed.

Adult↗
PubMedDate not supplied

Chronic obstructive pulmonary disease: capillarity and fiber-type characteristics of skeletal muscle.

BACKGROUND: The purpose of this investigation was to compare capillarity and fiber type proportions of the vastus lateralis muscle between patients with chronic obstructive pulmonary disease (COPD) and healthy subjects. METHODS: Fifteen male subjects were included in the study (8 COPD: 61.0 +/- 1.8 years [mean +/- SEM]; forced expiratory volume in 1 second 42.0 +/- 2.1% predicted; 7 N: age 54.0 +/- 1.1). Subjects were submitted to a symptom-limited maximal exercise test on ergocycle. After a transcutaneous biopsy of the vastus lateralis muscle, sections were cut 8 to 10 microns thick and stained with the Andersen method for capillarity and Stevens method for fiber typing. RESULTS: Patients with COPD had a decrease in peak oxygen consumption compared with healthy subjects (1.2 +/- 0.1 versus 3.0 +/- 0.2 L/min). Number of capillaries per square millimeter was lower in patients with COPD versus healthy subjects (92.6 +/- 16.1 and 213.3 +/- 33.5, P < 0.001); percentages of fiber types were 43.5 +/- 5.5% type I, 56.5 +/- 5.5% type II in COPD, and 56.7 +/- 3.4% type I, 43.2 +/- 3.4% type II in healthy subjects (P < 0.05). In addition, capillaries/fiber ratio was 0.83 +/- 0.05 in COPD, and 1.56 +/- 0.10 in healthy subjects (P < 0.001). CONCLUSION: As expected, patients with COPD showed a decrease in exercise capacity. The muscle analysis results indicate that patients with COPD have a greater proportion of type II fibers and a much lower capillaries/fiber ratio than normal subjects. We conclude that COPD adversely affects fiber type and capillarization of the lower limbs. This could be partly caused by deconditioning in these patients.

Adult↗
PubMedDate not supplied

[Reintegration to work in persons having survived a myocardial infarction: current review and ways of development for clinical interventions].

The main purpose of this article is to update the state of knowledge regarding work reintegration following myocardial infarction. Occupational perspectives have greatly evolved during the second half of this century. This can be attributed mainly to a better understanding of the pathology itself and to a development of new therapeutic avenues which are part of a more global vision of the bio-psycho-social characteristics of the patient. The authors did not intend to realize an extensive review of the literature on the subject, but analysed the most significant articles published over the past 20 years. They were selected because of their frequent citation on the scientific literature which seems to confirm their significance and credibility. Following the analysis of the articles selected, the authors conclude that the scientific community has reached a consensus to the effect that the general evolution of the patient post myocardial infarction is greatly determined by psychosocial factors. It follows that comprehensive rehabilitation programs despite their limited impact in an experimental setting offer some stimulating perspectives. They suggest that some research effort be oriented towards the evaluation of the actual long term outcomes of rehabilitative programs especially on quality of life in general and on quality of life at work more specifically.

Employment↗