Adsorption of polyamine on clay minerals.

This work aims at a better understanding of the interaction between a polycationic quaternary amine polymer (F25) and three different clay minerals: montmorillonite, illite, and kaolinite. For this, adsorption isotherms of F25 on the clay surfaces were measured together with the evolution of the CEC along the isotherm, which revealed that cation exchange plays an important role in the adsorption process. These first results were confirmed by XRD measurements on dried powders that are evidence in the case of montmorillonite of the presence of polymer in the interlayer spaces. In addition, the evolution of the short range structure of clay minerals suspensions on polymer adsorption was followed by WAXS experiments. Polymer intercalation was observed while the structure of the resulting stacking appeared to change slightly along the polymer adsorption isotherm. Diffuse reflectance infrared measurements revealed that significant conformational changes occur on polymer adsorption onto montmorillonite surfaces. Furthermore, adsorption above the CEC is observed which involves a charge reversal of clay mineral surfaces, the zero charge being reached for an adsorbed amount corresponding to the CEC. Finally, flocculation was discussed compared to adsorption amounts and zeta potential measurements, confirming that optimum flocculation concentration is reached for noncharged particles.

[Use of a structured diagnostic interview to identify depressive episodes in an epidemiologic study: a posteriori internal validation]. / Utilisation d'un entretien diagnostique structuré pour identifier les épisodes dépressifs dans une étude épidémiologique: validation interne a posteriori.

BACKGROUND: During these last years, many structured and standardized diagnostic interviews have been developed in order to identify psychiatric disorders in a standardized way. These tools enable a systematic investigation of these disorders according to international classifications. Their main drawback is to be long. To assess the care of depression, we used a shorter and more simple tool: the Mini International Neuropsychiatric Interview (MINI) to identify depressive subjects. METHOD: The study was conducted in the Gazel cohort from the French National Electricity and Gas Company. A stratified sample of 2394 civil servants selected in order to over-represent depressive subjects was asked to answer to the MINI interview through a phone interview. An epidemiological and statistical analysis was performed to test the MINI internal validity: prevalence of depressive disorders using different threshold of diagnosis (number of symptoms required to identify someone as depressive), frequency of different symptoms, variability between investigators and potential biases. RESULTS: Respondents to the phone interview (1108 civil servants) had more often presented depression markers for the last 5 years. Prevalence of depressive episodes changed little when we varied the threshold of diagnosis and did not stress any threshold problem. The variability between investigators was important, but the estimation of prevalence remained stable when we excluded extreme rates of prevalence. The choice of a classification system affected the prevalence estimation. Using the Diagnostic and Statistical Manual of Mental Disorders (DSM IV) from the American Psychiatric Association, the prevalence of depressive episodes was lower and closer to the estimations shown in the literature than using the International Classification of Disease (ICD 10). Moreover, the stratification assigned very unbalanced weights to the stratification strata. By excluding depressive episodes observed in the stratum "control" (no depression "marker" from 1989 to 1994 in the database), the prevalence was very lower, whatever the classification was. Finally, factors which appeared linked to care of depression with the ICD definition remained the same when the DSM diagnosis definition was used, and relative risks were quite similar. CONCLUSION: The MINI appears to be a short and simple tool, suited to the epidemiological studies. This analysis does not highlight any failure in the internal consistency of the MINI. The remaining question is what the MINI really measures, particularly comparing to a psychiatrist's diagnosis.

[Prevention of osteoporosis and its economic aspects]. / La prévention de l'ostéoporose et ses incidences economiques.

Osteoporosis is a skeletal disease which deteriorates bone tissue and lowers its density. Bone fragility induces fractures of the hip, vertebrae and distal radius. These fractures occur mainly to women after their menopause due to important postmenopausal changes in bone metabolism. Osteoporosis and related fractures are a major public health issue, as the upcoming population aging will sharply increase their incidence. For the time being prevention of osteoporosis is at a crossroads in France. One way would be to treat the entire postmenopause female population with hormone substitution to avoid the incidence to one third among them: the cost would be very high and, for the time being, the risk/benefit ratio is not well known (we do not know the risks of a treatment lasting 20 or 25 years). The other way would be to implement only reliable diagnostic programs without generalized hormone treatment: such an option might lead to a sharp increase of the disease incidence, causing a high cost both in social and financial terms.

Which patients receive antidepressants? A 'real world' telephone study.

INTRODUCTION: The use of antidepressants has been questioned with respect to both undertreatment and inadequate prescription. The present investigation was therefore launched to assess the psychopathology profiles of antidepressant users. METHODS: A representative sample was constituted on the basis of usual antidepressant consumption, and ICD 10 compatible diagnoses were obtained after telephone administration of a structured psychiatric interview. RESULTS: The most often used drugs were fluoxetine, followed by tricyclic antidepressants. Coprescription existed in slightly less than two thirds of antidepressant users. ICD 10 diagnoses were compared to currently available prescription guidelines. Fluoxetine prescription, as compared to other drugs, was found to be significantly more compliant with these guidelines; conversely, in 22% of antidepressant users, no complete ICD 10 diagnosis could be documented. These results are discussed in the light of report accuracy and anecdotal or 'heterodox' indications of antidepressants. CONCLUSION: Altogether, the present study confirms previous doubts regarding appropriate use of antidepressants and stresses the need for more explicit and comprehensive clinical guidelines. It does not substantiate, however, any evidence for a 'recreational' use of these products.

[Pharmaco-epidemiologic study of the use of antidepressant drugs in the general population]. / Etude pharmaco-épidémiologique de la consommation des antidépresseurs en population générale.

The objective of this study was to evaluate the mode of prescription and the users of antidepressant agents. It consisted of an initial phase (survey of the general population), aimed at selecting a representative sample of antidepressants users by a mail questionnaire, without asking prescribers in order to avoid the bias inherent to such an approach. Results showed a current incidence of use of 2.75 % for the 8 main antidepressants, i.e. more than one million adults in France. The distribution of antidepressants showed Prozac in first place, followed by Anafranil, and Laroxyl, then Stablon, Athymil, Survector and Ludiomil. In more than 50 % of cases, antidepressants have been taken for a year or more, continuously of intermittently. They were prescribed by a general practitioner in 60 % of cases and a psychiatrist in 30 %. A second survey phase (telephone) undertaken by psychiatrists and involving a sample of this population enabled determination of the pathophysiological profile of consumers at the time of prescription of antidepressant treatment, using a validated diagnostic tool, the MINI. Taking all drugs together, results showed that prescription was within Marketing Authorization approved indications in about 65 % of cases (existence of depression 61 %, dysthymia 3 %, OCD 1 %). This study shows that, in 23 % of cases, antidepressants are not used in patients with one of the psychiatric diseases identified by the MINI but nevertheless suffering from pathophysiological symptoms (subsyndronic syndrome). It can be concluded that, in some subjects, antidepressants are used in non-identified disorders. It must also be recognized that, with 3 % of users, the population of individuals treated by antidepressants is less than that of patients suffering, in the general population, from depression (5 to 10 % per year, according to studies).

[Interest in amd methodology of medical-economic studies in perspective]. / Intérêt et méthodologie des études médico-économiques en situation.

Clinicians and economists must collaborate for conception and achievement of clinical-economic studies. If economists are more involved in some decisions such as costs or perspectives selection, other aspects such as general design, data collection methods, endpoints, comparator or procedures must be chosen both by clinicians, epidemiologists and economists. This is the condition for a good data validity, a wide diffusion and exploitation of clinical-economic studies in the future. The introduction of this type of studies should bring interesting data on the care of diabetic patients.