Biomedical subjects

J L Bosson

Publications and source records attributed to J L Bosson.

7 recordsLinked to original sources

PubMed1992

[Malignant cervical epithelial adenopathy from unknown primary source. Apropos of a series of 54 cases].

Fifty four patients with cervical lymph node metastasis from an unknown primary tumor underwent treatment from 1969 to 1988. Fourty five underwent radical neck dissection. 69% had node capsular effraction and 36% perinodal vascular embolism. Thirty four patients underwent postoperative radiotherapy including rhinopharynx, cervical oesophagus and all the bilateral cervical nodes. The primary tumor appeared after treatment in 7 cases. Total survival rate is 36% 5 years after treatment. Vascular embolism aggravates the prognosis. Radiosurgical association allow effective control of loco-regional cancer but does not improve survival rate. Prognosis is aggravated by metastases arising (18%).

Adult↗

PubMed1992

[Thrombosis, immunology and drugs].

Diagnosis of thrombopenia due to heparin in sometimes false. We present a case with venous thrombosis in whom the suspicion of thrombopenia induced by heparin finally proved to be a quinidine induced lupus. Related to this observation we emphasise the importance of immunological investigation in patient with venous thrombosis.

Diagnosis, Differential↗

PubMed1991

Formulas for threshold computations.

Given a continuous variable S, which density functions on two subgroups omega + and omega - of a population omega are known (with for instance a higher mean value on omega + than on omega -), we first define two strategies for classification in these groups; the first one (MWC) consists in determining a threshold alpha such that classifying in omega + when S greater than or equal to alpha, in omega - otherwise, leads to the highest percentage of well-classed elements. The second one consists in choosing the most probable group, given the observed value of S. We give mathematical formulas for the thresholds involved in these two strategies when the density functions, determined by the application of the maximum entropy principle, are those of normal distributions. These formulas prove that the two considered strategies are frequently equivalent, and we give simpler formulas when the partial variances of S on omega + and omega - are unknown or approximately equal. All the formulas are adapted to the case where a cost coefficient is introduced to display the unequal seriousness of the two possible errors (misclassification in omega + or omega -). Then we consider an example, where we see that the computed thresholds can be graphically validated from empirical curves and have the same performances on the learning sample and on a test sample.

Analysis of Variance↗

PubMed1991

Strategies for graphical threshold determination.

Determining a threshold for a quantitative variable (arising in biological measurements for instance) is a common problem in medical decision making. We define seven commonly used strategies: each one leads to an optimal determination. To these strategies correspond relevant empirical curves: the ROC curve for strategies involving the sensitivity or the specificity, the predictive ROC curve (P-ROC curve) for strategies involving the positive and negative predicting values, and the well classified frequencies curve (WCF curve) for classification strategies where all misclassifications have the same importance. For one of the considered strategies, there also exists a theoretical formula for the optimal threshold, elicited within a classical probabilistic model, which gives a considerable advantage to this strategy. These strategies are applied to a stimulated example containing 702 cases, where we see that they lead to different optimal threshold values. Finally, we briefly review a practical application in the determination of thresholds for glycemia measurements, leading to the choice of one of them as the optimal one to consider in the gestational diabetes mellitus prediction.

Diagnosis, Computer-Assisted↗

PubMed1991

Role of splenectomy in incidence and severity of acute graft-versus-host disease: a multicenter study of 157 patients.

Allogeneic bone marrow transplantation is a therapeutic option for many hematological malignancies. Graft-versus-host disease (GVHD) remains one of the major complications and has a high mortality rate. The pathophysiological mechanisms involved are poorly understood and GVHD prevention regimens still give disappointing results. This study concerned 157 patients with diverse diagnoses from Bordeaux, Grenoble and Marseille who had undergone an HLA-matched transplantation without T cell depletion. Thirty-one patients (20%) had been splenectomized before transplantation. The role of splenectomy in the incidence and severity of acute GVHD was investigated using a univariate and multivariate analysis of 11 risk factors including splenectomy. Univariate analysis found three significant risk factors linked with GVHD incidence: splenectomy, age of recipient and GVHD prevention by monotherapy versus a combination of methotrexate plus cyclosporin. Multivariate analysis retained only the effects of age and GVHD prevention on GVHD incidence and showed that splenectomy was the most important factor in GVHD severity. One explanation for the role of splenectomy could be the spleen's possible function as a filter of activated T lymphocytes from the transplant. We therefore concluded that it would be preferable to abstain from splenectomizing patients before transplantation although splenectomy is still advisable in certain malignancies after transplantation.

Acute Disease↗

PubMed1990

Seborrheic dermatitis and HIV infection. Qualitative analysis of skin surface lipids in men seropositive and seronegative for HIV.

We measured skin surface lipids (cholesterol, free fatty acids, triglycerides, wax esters, and squalene) in patients seropositive for human immunodeficiency virus (HIV) and those seronegative for HIV with and without seborrheic dermatitis. Cholesterol and wax ester fractions were similar in all four groups but triglycerides and squalene were significantly increased and free fatty acids significantly decreased in HIV-positive patients, regardless of the presence of seborrheic dermatitis. In addition, a strong negative correlation was found between free fatty acid and triglyceride levels. We conclude that abnormalities of skin surface lipids are not associated with the development of seborrheic dermatitis in HIV-positive persons but are associated with HIV infection itself.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Echographic and Doppler screening of the forearm arteries in professional volleyball players.

We evaluated nine professional volleyball players by clinical, echographic, and Doppler technique examination of the forearm and digital arteries to determine vascular damage caused by repeated trauma. The results of these tests showed that one-third of the subjects had vascular lesions in the right hand; only one of these was symptomatic. This suggests that noninvasive screening should be recommended and included in the regular medical check-ups of professional athletes in whom repeated trauma to the hand is likely, such as volleyball players.

Adult↗