Renal sodium handling in acute and chronic salt loading/depletion protocols: the confounding influence of acute water loading.

OBJECTIVES: Renal tubular sodium handling was measured in healthy subjects submitted to acute and chronic salt-repletion/salt-depletion protocols. The goal was to compare the changes in proximal and distal sodium handling induced by the two procedures using the lithium clearance technique. METHODS: In nine subjects, acute salt loading was obtained with a 2 h infusion of isotonic saline, and salt depletion was induced with a low-salt diet and furosemide. In the chronic protocol, 15 subjects randomly received a low-, a regular- and a high-sodium diet for 1 week. In both protocols, renal and systemic haemodynamics and urinary electrolyte excretion were measured after an acute water load. In the chronic study, sodium handling was also determined, based on 12 h day- and night-time urine collections. RESULTS: The acute and chronic protocols induced comparable changes in sodium excretion, renal haemodynamics and hormonal responses. Yet, the relative contribution of the proximal and distal nephrons to sodium excretion in response to salt loading and depletion differed in the two protocols. Acutely, subjects appeared to regulate sodium balance mainly by the distal nephron, with little contribution of the proximal tubule. In contrast, in the chronic protocol, changes in sodium reabsorption could be measured both in the proximal and distal nephrons. Acute water loading was an important confounding factor which increased sodium excretion by reducing proximal sodium reabsorption. This interference of water was particularly marked in salt-depleted subjects. CONCLUSION: Acute and chronic salt loading/salt depletion protocols investigate different renal mechanisms of control of sodium balance. The endogenous lithium clearance technique is a reliable method to assess proximal sodium reabsorption in humans. However, to investigate sodium handling in diseases such as hypertension, lithium should be measured preferably on 24 h or overnight urine collections to avoid the confounding influence of water.

Symptômes dépressifs et douleurs diffuses chez un détenu : penser au déficit en vitamine D [Depressive symptoms and widespread pains in a prisoner. Think on vitamin D deficiency].

The confinement can lead to an important limitation of sun exposure of the prisoners. This limitation can lead to a deficit in vitamin D, source of diverse disorders. Diffuse pains of members and of joints are the most classics troubles. The association of vitamin D deficiency and psychiatric disorders is frequent but badly known. Even if there is still no evidence indicating a cause and effect relationship between vitamin D deficiency and depressive episodes, the contribution of vitamin D deficiency in the arisen of a depression has to be considered. The treatment of vitamin D deficiency cannot, in itself, constitute a treatment of the depressive disorder but contributes to the improvement of the whole status The psychiatric follow-up remains indispensable, in particular because of the suicidal risk, particularly present in prison.

Subthalamic nucleus deep brain stimulation for Parkinson's disease : "Are we where we think we are ?

ABSTRACT High frequency electrical deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a worldwide recognized therapy for the motor symptoms of Parkinson's disease in fluctuating patients who are progressively disabled despite medical treatment adjustments. However, such improvements emerge despite a lack of understanding of either the precise role of STN in human motor control or the mechanism(s) of action of DBS. Through the question "are we where we think we are", this thesis is first dedicated to the control of the position of the preoperatively defined target and of the implanted electrodes on magnetic resonance imaging (MRI). This anatomical approach will provide a way to identify more precisely the structure(s) involved by electrical stimulation. Then, a study of the correlation existing between the position of the preoperative target and the position of the electrode is performed. In this part, a unique opportunity is given to identify factors that may affect these correlation results. Finally, the whole work represents a « quality assessment » of the crucial steps of STN DBS: first, the target and the implanted electrode localisation procedures that have been developed in collaboration with the Radiological department; second the implantation procedure that has been performed nowadays on more than 50 parkinsonian patients in the Neurosurgical department of the Centre Hospitalier Universitaire Vaudois in collaboration with the Neurological department. This work is especially addressed to the multidisciplinary medical team involved in the surgical treatment of movement disorders, including also neurophysiologists, neuropsychologists and psychiatrists. RESUME La stimulation électrique à haute fréquence du noyau sous-thalamique est à ce jour mondialement reconnue pour le traitement des symptômes moteurs de la maladie de Parkinson chez des patients sévèrement atteints et chez qui la réponse fluctuante au traitement médicamenteux ne peut être améliorée de façon satisfaisante. Cependant, les résultats observés surviennent malgré une compréhension approximative et controversée du rôle réel du noyau sous-thalamique dans le contrôle du mouvement volontaire aussi bien que des mécanismes d'action de la stimulation cérébrale profonde. A travers la question « sommes-nous où nous pensons être », cette thèse est tout d'abord consacrée à l'étude du contrôle de la position de la cible définie avant l'intervention et de la position des électrodes implantées sur l'imagerie par résonance magnétique (IRM). Cette approche anatomique permettra d'identifier plus précisément la (les) structure(s) influencées par la stimulation électrique. Ensuite, une étude de la corrélation existant entre la position de la cible préopératoire et la position des électrodes implantées est effectuée. Elle a pour but de mettre en évidence les facteurs influençant les résultats de cette corrélation. Enfin, le travail dans son ensemble est un « contrôle de qualité » des étapes cruciales de la stimulation du noyau sous-thalamique : premièrement, des méthodes de localisation de la cible et des électrodes implantées effectuées sur IRM, développées en collaboration avec le service de Radiologie ; deuxièmement, de la méthode d'implantation utilisée à ce jour chez plus de 50 patients dans le service de Neurochirurgie du Centre Hospitalier Universitaire Vaudois en collaboration avec le service de Neurologie. Ce travail s'adresse spécialement aux équipes médicales pluridisciplinaires impliquées dans le traitement chirurgical des mouvements anormaux, incluant également des neurophysiologistes, des neuropsychologues et des psychiatres.

Do brief alcohol motivational interventions work like we think they do?

BACKGROUND: Questions remain about how brief motivational interventions (BMIs) for unhealthy alcohol use work, and addressing these questions may be important for improving their efficacy. Therefore, we assessed the effects of various characteristics of BMIs on drinking outcomes across 3 randomized controlled trials (RCTs). METHODS: Audio recordings of 314 BMIs were coded. We used the global rating scales of the Motivational Interviewing Skills Code (MISC) 2.1: counselor's acceptance, empathy, and motivational interviewing (MI) spirit, and patient's self-exploration were rated. MI proficiency was defined as counselor's rating scale scores ≥5. We also used the structure, confrontation, and advice subscale scores of the Therapy Process Rating Scale and the Working Alliance Inventory. We examined these process characteristics in interventions across 1 U.S. RCT of middle-aged medical inpatients with unhealthy alcohol use (n = 124) and 2 Swiss RCTs of young men with binge drinking in a nonclinical setting: Swiss-one (n = 62) and Swiss-two (n = 128). We assessed the associations between these characteristics and drinks/d reported by participants 3 to 6 months after study entry. RESULTS: In all 3 RCTs, mean MISC counselor's rating scales scores were consistent with MI proficiency. In overdispersed Poisson regression models, most BMI characteristics were not significantly associated with drinks/d in follow-up. In the U.S. RCT, confrontation and self-exploration were associated with more drinking. Giving advice was significantly associated with less drinking in the Swiss-one RCT. Contrary to expectations, MI spirit was not consistently associated with drinking across studies. CONCLUSIONS: Across different populations and settings, intervention characteristics viewed as central to efficacious BMIs were neither robust nor consistent predictors of drinking outcome. Although there may be alternative reasons why the level of MI processes was not predictive of outcomes in these studies (limited variability in scores), efforts to understand what makes BMIs efficacious may require attention to factors beyond intervention process characteristics typically examined.

Aliments et boissons allégés: qu'en penser [Light food and beverages: what to think about?].

Light food and beverages are increasing on the market for many years, first for economic reasons and, more and more for aesthetisme, however without aimed a defined population. The interest of these products is not evident, reason why it is difficult to get a clear and objective opinion without being influenced by marketing messages. Under what circumstances can they be a solution? Can we advise them? Do they have an influence in the loss or weight control? This article offers some thoughts and suggestions on the use of these specific products.

Sleep deprivation (SD) on focal brain ischemia in the rat : effects of different SD protocols

Sleep-wake disturbances are frequently observed in stroke patients and are associated with poorer functional outcome. Until now the effects of sleep on stroke evolution are unknown. The purpose of the present study was to evaluate the effects of three sleep deprivation (SD) protocols on brain damages after focal cerebral ischemia in a rat model. Permanent occlusion of distal branches of the middle cerebral artery was induced in adult rats. The animals were then subjected to 6h SD, 12h SD or sleep disturbances (SDis) in which 3 x 12h sleep deprivation were performed by gentle handling. Infarct size and brain swelling were assessed by Cresyl violet staining, and the number of damaged cells was measured by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) staining. Behavioral tests, namely tape removal and cylinder tests, were performed for assessing sensorimotor function. In the 6h SD protocol, no significant difference (P > 0.05) was found either in infarct size (42.5 ± 30.4 mm3 in sleep deprived animals vs. 44.5 ± 20.5 mm3 in controls, mean ± s.d.), in brain swelling (10.2 ± 3.8 % in sleep deprived animals vs. 11.3 ± 2.0 % in controls) or in number of TUNEL-positive cells (21.7 ± 2.0/mm2 in sleep deprived animals vs. 23.0 ± 1.1/mm2 in controls). In contrast, 12h sleep deprivation increased infarct size by 40 % (82.8 ± 10.9 mm3 in SD group vs. 59.2 ± 13.9 mm3 in control group, P = 0.008) and number of TUNEL-positive cells by 137 % (46.8 ± 15/mm in SD group vs. 19.7 ± 7.7/mm2 in control group, P = 0.003). There was no significant difference (P > 0.05) in brain swelling (12.9 ± 6.3 % in sleep deprived animals vs. 11.6 ± 6.0 % in controls). The SDis protocol also increased infarct size by 76 % (3 x 12h SD 58.8 ± 20.4 mm3 vs. no SD 33.8 ± 6.3 mm3, P = 0.017) and number of TUNEL-positive cells by 219 % (32.9 ± 13.2/mm2 vs. 10.3 ± 2.5/mm2, P = 0.008). Brain swelling did not show any difference between the two groups (24.5 ± 8.4 % in SD group vs. 16.7 ± 8.9 % in control group, p > 0.05). Both behavioral tests did not show any concluding results. In summary, we demonstrate that sleep deprivation aggravates brain damages in a rat model of stroke. Further experiments are needed to unveil the mechanisms underlying these effects.

Improving telecommunication security level by integrating quantum key distribution in communication protocols

Résumé La cryptographie classique est basée sur des concepts mathématiques dont la sécurité dépend de la complexité du calcul de l'inverse des fonctions. Ce type de chiffrement est à la merci de la puissance de calcul des ordinateurs ainsi que la découverte d'algorithme permettant le calcul des inverses de certaines fonctions mathématiques en un temps «raisonnable ». L'utilisation d'un procédé dont la sécurité est scientifiquement prouvée s'avère donc indispensable surtout les échanges critiques (systèmes bancaires, gouvernements,...). La cryptographie quantique répond à ce besoin. En effet, sa sécurité est basée sur des lois de la physique quantique lui assurant un fonctionnement inconditionnellement sécurisé. Toutefois, l'application et l'intégration de la cryptographie quantique sont un souci pour les développeurs de ce type de solution. Cette thèse justifie la nécessité de l'utilisation de la cryptographie quantique. Elle montre que le coût engendré par le déploiement de cette solution est justifié. Elle propose un mécanisme simple et réalisable d'intégration de la cryptographie quantique dans des protocoles de communication largement utilisés comme les protocoles PPP, IPSec et le protocole 802.1li. Des scénarios d'application illustrent la faisabilité de ces solutions. Une méthodologie d'évaluation, selon les critères communs, des solutions basées sur la cryptographie quantique est également proposée dans ce document. Abstract Classical cryptography is based on mathematical functions. The robustness of a cryptosystem essentially depends on the difficulty of computing the inverse of its one-way function. There is no mathematical proof that establishes whether it is impossible to find the inverse of a given one-way function. Therefore, it is mandatory to use a cryptosystem whose security is scientifically proven (especially for banking, governments, etc.). On the other hand, the security of quantum cryptography can be formally demonstrated. In fact, its security is based on the laws of physics that assure the unconditional security. How is it possible to use and integrate quantum cryptography into existing solutions? This thesis proposes a method to integrate quantum cryptography into existing communication protocols like PPP, IPSec and the 802.l1i protocol. It sketches out some possible scenarios in order to prove the feasibility and to estimate the cost of such scenarios. Directives and checkpoints are given to help in certifying quantum cryptography solutions according to Common Criteria.

Hypotension orthostatique: à quoi penser et que faire? [Orthostatic hypotension: what to think of it and what to do?].

Orthostatic hypotension is encountered frequently in everyday practice. It is often very disabling because of its troublesome symptomalogy. Orthostatic hypotension may be due to several causes and can be easily diagnosed by measuring blood pressure and heart rate after 3 minutes in upright posture. Its treatment comprises in all cases non-pharmacological interventions which can be associated whenever required by medications, in particular midodrine and fludrocortisone.

Fate of clinical research studies after ethical approval--follow-up of study protocols until publication.

BACKGROUND: Many clinical studies are ultimately not fully published in peer-reviewed journals. Underreporting of clinical research is wasteful and can result in biased estimates of treatment effect or harm, leading to recommendations that are inappropriate or even dangerous. METHODS: We assembled a cohort of clinical studies approved 2000-2002 by the Research Ethics Committee of the University of Freiburg, Germany. Published full articles were searched in electronic databases and investigators contacted. Data on study characteristics were extracted from protocols and corresponding publications. We characterized the cohort, quantified its publication outcome and compared protocols and publications for selected aspects. RESULTS: Of 917 approved studies, 807 were started and 110 were not, either locally or as a whole. Of the started studies, 576 (71%) were completed according to protocol, 128 (16%) discontinued and 42 (5%) are still ongoing; for 61 (8%) there was no information about their course. We identified 782 full publications corresponding to 419 of the 807 initiated studies; the publication proportion was 52% (95% CI: 0.48-0.55). Study design was not significantly associated with subsequent publication. Multicentre status, international collaboration, large sample size and commercial or non-commercial funding were positively associated with subsequent publication. Commercial funding was mentioned in 203 (48%) protocols and in 205 (49%) of the publications. In most published studies (339; 81%) this information corresponded between protocol and publication. Most studies were published in English (367; 88%); some in German (25; 6%) or both languages (27; 6%). The local investigators were listed as (co-)authors in the publications corresponding to 259 (62%) studies. CONCLUSION: Half of the clinical research conducted at a large German university medical centre remains unpublished; future research is built on an incomplete database. Research resources are likely wasted as neither health care professionals nor patients nor policy makers can use the results when making decisions.