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Biomedical subjects

E Lesaffre

Publications and source records attributed to E Lesaffre.

At least 109 records · Page 6Linked to original sources
PubMed1988

The Ionescu-Shiley pericardial valve: results in 473 patients.

From January 1, 1980, through December 31, 1985, 473 patients underwent valve replacement with an Ionescu-Shiley valve. Overall hospital mortality was 7.8%. Major associated procedures and preoperative New York Heart Association (NYHA) Classes IV and V influenced hospital mortality significantly. The mean follow-up was 2.6 +/- 1.3 years. Late mortality was 5.9%. Overall actuarial survival was 81% at 5 years. A chief cause of reoperation was cusp rupture of a mitral prosthesis in 5 patients (all after aortic and mitral valve replacement). The overall actuarial reoperation-free incidence was 93% at 5 years. Thromboembolic (TB) phenomena occurred at a linear incidence of 1.4 +/- 0.3% per patient-year or an actuarial thromboembolism-free incidence of 92% at 5 years. Univariate and multivariate analyses showed that postoperative NYHA Class, rhythm at follow-up, and anticoagulant therapy significantly influenced the incidence of TE phenomena.

Aged↗
PubMed1988

UV sunlight and patch test reactions in humans.

No seasonal influence of UV sunlight on patch test reactions in humans over a period of 9 years of clinical practice was found in this retrospective study of almost 8000 patients. Although the mean UV monthly dose varies seasonally, up in the summer and down in the winter, no significant differences could be identified for patch test reactions, either for the mean number of positive test reactions or for the intensity of the skin reaction or for the id-like spread reactions seen in summer or winter. Furthermore, no short-term influences of UV exposure during the weekend preceding patch testing could be demonstrated. Therefore, reliable patch-test results can be expected at any season of the year from a general population, at least in Belgian-type climates.

Belgium↗
PubMed1988

Statistical pitfalls in the analysis of age-related effects in antihypertensive therapy.

Much of the literature concerning age-related effects in antihypertensive therapy suffers from serious deficiencies in statistical design and analysis. The problems include those relating to the choice of a suitable control group, the measurement of response to treatment, response to baseline blood pressure, interpreting post hoc analyses, and the pooling of data from a number of related studies. These problems are discussed and we attempt to identify solutions that give a satisfactory balance between scientific validity and the real-life problems of conducting clinical trials. We conclude by outlining a protocol for future studies in this area.

Aged↗
PubMed1988

Interpreting age-related aspects of antihypertensive treatment: statistical defects and their remedy.

Much of the literature concerning age-related effects in hypertension and its treatment suffers from serious deficiencies in statistical design and analysis. The problems include the measurement of response to treatment, the lack of a suitable control group, the way response is related to baseline blood pressure, the interpretation of post hoc analyses and the pooling of data from related but different studies. We discuss these problems and attempt to identify solutions which give a satisfactory balance between scientific validity and the practical issues of conducting clinical trials in hypertension.

Age Factors↗
PubMed1987

Comparison of the classification ability of the electrocardiogram and vectorcardiogram.

Controversy exists over the classification ability of the standard 12-lead electrocardiogram (EGG) and the vectorcardiogram (VCG). In this study the diagnostic information content and classification performance of the ECG and VCG were examined using multivariate statistical techniques and a large validated data base of 3,266 cases. Logistic classification models were developed to differentiate between 7 diagnostic entities: normal (n = 538), left (n = 557), right (n = 323) and biventricular (n = 437) hypertrophy, and anterior (n = 390), inferior (n = 657) and combined (n = 364) myocardial infarction. The models were obtained from a learning sample (n = 2,446) using an optimal set of computer derived ECG and VCG measurements. They were subsequently applied to a test sample (n = 820). In the learning sample, the discrimination models resulted in a total correct classification rate of 69.6% for the ECG and 69.4% for the VCG. The total accuracy rate was slightly lower in the test set: 66.3% for the ECG and 67.1% for the VCG. The combined use of the best ECG and VCG variables did not increase total diagnostic accuracy. When cases with biventricular hypertrophy and combined infarction were deleted, accuracy rates of more than 80% were achieved for both lead systems. Differences in the classification rates for the subgroups were not statistically significant. Thus, the conventional 12-lead ECG is as good as the VCG for the differential diagnosis of 7 main entities, provided identical procedures are used in the design of the classifiers.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiomegaly↗
PubMed1987

Comparison of multigroup logistic and linear discriminant ECG and VCG classification.

The performance of logistic (LOG) and linear discriminant analysis (LDA) has been studied, both for the conventional 12-lead electrocardiogram (ECG) and the orthogonal Frank 3-lead electrocardiogram (VCG), using a large validated data base. Classification rules were derived form a learning set (N = 2446) and applied to a test set (N = 820) to differentiate between normal, left, right and biventricular hypertrophy, anterior, inferior and combined myocardial infarction (MI). Total accuracy of LOG, assuming no normal distribution and using population proportions as prior probabilities, was up to 3% higher than that of LDA, depending on the number of variables used. The 12- and 3-lead LOG and LDA formulas resulted in very similar accuracy rates, i.e., between 67 and 70% for the seven-group and between 77 and 84% for the five-group analysis. LDA posterior probabilities were systematically more extreme than LOG ones. Correct classification of normals' specificity by LDA was 5 to 9% higher, but sensitivity for different groups was 1.5 to 10% lower than by LOG, with sample size proportions as priors. Specificity could be improved by changing the priors at the cost of lower sensitivity and vice versa, both for the LDA and LOG models. Classification results at 95% specificity were only slightly different, except for anterior MI where LOG scored 6% better. Other measures of performance demonstrated that the LDA model was overconfident and that the LOG model fitted better the real class membership of the patients. In conclusion, logistic ECG and VCG models improve the total accuracy of classification by about 1 to 3% when compared to LDA. More importantly, reliability of classification represents the improvement we want to emphasize. These methods may enhance the diagnostic utility of the ECG and VCG in routine practice.

Analysis of Variance↗
PubMed1987

The value of ejection fraction as a predictor of early and late survival following aortocoronary bypass surgery in patients with moderate to severe depression of the left ventricular function.

Predictability analysis of early and late survival of coronary bypass patients with reduced left ventricular function was performed using stepwise logistic regression based on preoperative and operative data. The total perioperative mortality was 3.4% and the total actuarial survival of the whole group at 42 months was 87.7%. Thirty preoperative and operative parameters of 149 patients were entered into a first mathematical model. Four parameters were selected as a consequence: ejection fraction, anginal class, obesity, septal infarct. A prediction model based on these parameters, gave a correct prediction of the operative outcome in 99.3% of the patients. However due to the only five perioperative deaths, this model should be interpreted with caution. The accuracy of ejection fraction alone was 97.3%, the sensitivity was 100% but the specificity was only 20%. The same parameters of 97 patients were entered into a second mathematical model. Four parameters were selected in this case: ejection fraction, NYHA functional classification, septal infarct, anterior infarct. A second prediction model, based on these parameters, gave a correct prediction of the late outcome at 24 months in 93.8% of the patients. The accuracy of the discrimination on the basis of ejection fraction alone was 89.7%, its sensitivity was 96.5% but its specificity was only 41.7%. Ejection fraction was the best predictor out of the studied variables but due to its low specificity not good enough as a sole parameter.

Adult↗
PubMed1986

Transcortin and vitamin D-binding protein levels in mouse serum.

The influence of age, sex and strain on the serum concentration of transcortin (corticosteroid-binding globulin) and vitamin D-binding protein (DBP) in mice was investigated. The effect of age was studied in two strains, C57BL/6JPfd and BALB/cmHeAPfd. The concentration of transcortin and DBP increased with age. In young animals the concentration of each protein showed a significant strain difference, which disappeared in older mice for DBP, but not for transcortin. In 7-day-old animals, no sex difference was observed for either protein, but in older animals a clear sex difference was found for transcortin. Adult males tended to have somewhat higher levels of DBP than adult females, but this difference was significant only on day 70. The variation in transcortin and DBP levels was further investigated in a large number of mouse strains. The DBP concentration did not markedly vary among strains (5.98-9.65 mumol/l in males and 5.08-8.85 mumol/l in females). Transcortin, however, showed marked strain variations, ranging from 0.72 to 2.06 mumol/l in males and from 1.02 to 4.55 mumol/l in females and there was a significant correlation (r = 0.66, n = 26, P less than 0.001) between the mean transcortin levels in males and females of different strains. Interstrain variation was much higher than intrastrain variation or variation among related strains, suggesting that the transcortin concentration is largely controlled by genetically determined factors. There was a significant correlation (r = 0.82, n = 9, P less than 0.01) between the mean corticosterone and transcortin concentrations (measured at 21.00 h).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1986

How predictable is the postoperative work resumption after aortocoronary bypass surgery?

The number of aortocoronary bypass procedures increased at the Cardiovascular Surgery Department of the University Hospital in Leuven (Belgium) from 12 patients in 1971 to 650 patients in 1983. A similar evolution took place in the other existing Belgian cardiovascular centers and new departments were created to fill this need. The financial burden of the direct hospital costs of these procedures on the National Health Care program is considerable. The postoperative work-resumption will restore the patient's social dignity, it can increase the patient's personal income and thus decrease the indirect costs such as workmen's compensation; it will therefore improve the cost effectiveness of coronary surgery so that it can be offered to the numerous patients who need it for their survival or for the improvement of their quality of life. Studies about the employment status before and after aortocoronary surgery, as published from other centers, can not be projected on the Belgian situation due to the difference in population cohorts, laws regulating the working conditions, the national unemployment ratio and disability compensations. With this in mind, a study of the preoperative and postoperative employment and its predictability was undertaken.

Adult↗
PubMed1985

Critical evaluation of quadratic logistic discriminant analysis methods: a case study.

Electrocardiographic measurements from two groups, patients with left ventricular hypertrophy and clinically normal cases, were analyzed to illustrate the performance of the linear logistic discrimination method in the case of very unequal covariance matrices. Two quadratic extensions of the linear model were critically investigated. The use of graphical methods to check the model has been stressed and illustrated.

Biometry↗
PubMed1985

Multivariate survival analysis for the assessment of prognostic factors and risk categories after recovery from acute myocardial infarction: the Belgian situation.

Twenty-one and a half per cent of the patients with acute myocardial infarction, admitted consecutively to the coronary care unit of the University Hospitals of Leuven in the period 1973-1979, died within 28 days. The 1,669 who recovered were followed between three and nine years. The mortality rate was 13.1% during the first year and fell to below 5% in the succeeding yearly intervals. Univariate and life table analysis were performed on noninvasive, clinical data collected during the coronary care unit stay for the total population and various subgroups. The Cox proportional hazards model was applied to the data in order to determine the prognostic factors for long-term survival. Of the 34 initially selected variables, the most dominant factors were age, Killip class III and IV, peripheral vascular disease, abnormal chest x-ray findings, previous infarction, and the use of digitalis or diuretics. The model, which was validated extensively, allowed the establishment of risk categories. Mortality five years after the acute event was 8.2 times more frequent in the highest risk quintile than in the lowest one. From this study one may conclude that multivariate techniques based on noninvasive variables collected during the coronary care unit stay are valuable for the determination of the long-term prognosis of patients with myocardial infarction.

Actuarial Analysis↗
PubMed1984

Serum lipids and apolipoproteins A-I, A-II and B in primary hypothyroidism before and during treatment.

Serum lipids and apolipoproteins (apo) A-I, A-II, and B were measured in twenty-four patients with severe primary hypothyroidism (Thyrotropin above 40 mU/l), before and during 1-thyroxine treatment. Apo A-I, A-II, and B were assayed by immunonephelometry, using monospecific antisera. The serum levels of total cholesterol (TC), of low-density lipoprotein cholesterol (LDLc), and of the major LDL apoprotein, apo B, were markedly increased in the untreated hypothyroid patients compared to the values during therapy (TC: mean +/- SD, 8.87 +/- 2.9 v. 5.48 +/- 1.6 mmol/l; LDLc: 6.66 +/- 2.6 v. 3.78 +/- 1.4 mmol/l; apo B: 1.66 +/- 0.48 v. 1.14 +/- 0.37 g/l; P less than 0.00001 for all variables). High-density lipoprotein cholesterol (HDLc) was slightly higher before than during therapy (1.58 +/- 0.7 v. 1.31 +/- 0.4 mmol/l; P less than 0.05), while the main HDL apoprotein, apo A-I, was significantly elevated (1.49 +/- 0.42 v. 1.13 +/- 0.27 g/l; P less than 0.0002). The increase of the second major HDL apoprotein, apo A-II, was less pronounced (0.33 +/- 0.1 v. 0.30 +/- 0.08 g/l; P less than 0.022). The apo A-I to apo A-II ratio, which reflects the relative concentrations of the HDL subfractions HDL2 and HDL3, was significantly higher before than during treatment (P less than 0.0006). Serum triglyceride levels were moderately elevated in the untreated hypothyroid patients (1.34 +/- 0.6 v. 0.95 +/- 0.4 mmol/l; P less than 0.002). The small decrease in body weight during therapy did not correlate with the changes of the various lipid and apoprotein parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Response of transcortin and alpha 2u-globulin to turpentine-induced inflammation in the rat: influence of corticosteroids and prolactin.

Evidence is presented that (transcortin and alpha 2u-globulin react as negative acute-phase proteins in the rat. Thirty-six hours after turpentine injection, the serum concentration of these proteins showed a two- to threefold decrease. Thereafter, transcortin rapidly returned to normal values, whereas alpha 2u-globulin remained low. This reaction pattern was still present after adrenalectomy, adrenalectomy and administration of glucocorticoids, and after treatment with bromocriptine, a suppressor of prolactin secretion. It is concluded that changes in the secretion of glucocorticoids and prolactin are not required for the observed turpentine-induced decrease of transcortin and alpha 2u-globulin.

Adrenalectomy↗
PubMed1982

Serum lipids and apolipoproteins A-I, A-II, and B in hyperthyroidism before and after treatment.

The serum concentrations of total cholesterol (TC), triglycerides (RG), high density lipoprotein-cholesterol (HDLc), low density lipoprotein-cholesterol (LDLc), and the apolipoproteins (apo) A-I, A-II, and B were measured in 33 hyperthyroid patients before and after treatment. The results were compared with those of healthy controls. Apo A-I, A-II, and B were assayed by immunonephelometry. The serum levels of TC (mean +/- SD, 167 +/- 36 mg/dl, HDLc (40.8 +/- 12 mg/dl), and LDLc (108 +/- 35 mg/dl) were decreased in the untreated hyperthyroid patients compared to both the values after treatment (TC: 215 +/- 54 mg/dl; P less than 0.001; HDLc: 52 +/- 14 mg/dl; P less than 0.001; LDLc: 146 +/- 47 mg/dl; P less than 0.001) and the control values (TC: 206 + 39 mg/dl; P less than 0.001; HDLc: 47.4 +/- 10 mg/dl; P les than 0.01; LDLc: 145 +/- 38 mg/dl; P less than 0.001). TG levels were not statistically different before and after treatment. The apo A-I concentrations (116 +/- 24 mg/dl) were lower before than after treatment (131 +/- 28 mg/dl; P less than 0.01), but they were not statistically different from those in the control group (115 +/- 19 mg/dl). The apo A-II levels were identical in all groups (before treatment, 35 +/- 7 mg/dl; after treatment, 37 +/- 9 mg/dl; control group, 36 +/- 9 mg/dl). The apo B levels were lower in the untreated hyperthyroid patients (86 +/- 23 mg/dl) compared to those in controls (103 +/- 19 mg/dl; P less than 0.001) and patients after therapy (103 +/- 25 mg/dl; P less than 0.001). The increase in HDLc relative to the major HDL apo A-I and A-II during treatment for hyperthyroidism was associated with changes in body weight. The apo A-I to apo A-II and LDLc to apo B ratios, however, were significantly lower before compared to those after treatment, when the influence of increasing body weight during therapy was accounted for. This study emphasizes the important regulating role of thyroid hormones on lipid and apolipoprotein metabolism.

Apolipoprotein A-I↗
PubMed1982

Incidence, growth and oestradiol-receptor levels of 7, 12-dimethylbenz (alpha) anthracene-induced mammary tumours in rats: effects of neonatal sex steroids and oestradiol implants.

The effects of neonatally administered steroids on the sensitivity of the mammary gland to tumour induction by 7, 12-dimethylbenz (alpha) anthracene was studied as a model for delayed (de) differentiating effects of steroid hormones. Immediately after birth male and female rats were gonadectomized and treated with testosterone, oestradiol or oil. Control animals were left intact. On day 45 all the gonadectomized animals and some of the control animals received an implant which delivered continuous low levels of oestradiol. The carcinogen was administered on day 55. The administration of an oestradiol implant, which increased prolactin levels in all animals, markedly reduced tumour incidence in intact female rats and increased tumour incidence in intact male rats. Neonatal administration of testosterone or oestradiol did not significantly influence tumour incidence, histopathology or oestradiol responsiveness in neonatally gonadectomized rats but tended to decrease tumour animals suggests that the effects observed by other authors in intact rats are mediated by changes in gonadal secretions. It is concluded that the hormonal environment during and after tumour induction plays a major role in the development of 7, 12-dimethylbenz (alpha) anthracene-induced mammary carcinomas.

9,10-Dimethyl-1,2-benzanthracene↗