Serum Leptin Concentration, Body Mass Index and Incident Heart Failure: The Health, Aging, and Body Composition Study

Background: Leptin is produced primarily by adipocytes. Although originally associated with the central regulation of satiety and energy metabolism, increasing evidence indicates that leptin may be an important factor for congestive heart faire (CHF). In the study, we aimed to test the hypothesis that leptin may influence CHF pathophysiology via a pathway of increasing body mass index (BMI). Methods: We studied 2,389 elderly participants aged 70 and older (M; 1161, F: 1228) without CHF and with serum leptin measures at the Health Aging, and Body Composition study. We analyzed the association between serum leptin level and risk of incident CHF using Cox hazard proportional regression models. Elevated leptin level was defined as more than the highest quartile (Q4) of leptin distribution in the total sample for each gender. Adjusted-covariates included demographic, behavior, lipid and inflammation variables (partially-adjusted models), and further included BMI (fully-adjusted models). Results: In a mean 9-year follow-up, 316 participants (13.2%) developed CHF. The partially-adjusted models indicated that men and women with elevated serum leptin levels (>=9.89 ng/ml in men and >=25 ng/ml in women) had significantly higher risks of developing CHF than those with leptin level of less than Q4. The adjusted hazard ratios (95%CI) for incident CHF was 1.49 (1.04 -2.13) in men and 1.71 (1.12 -2.58) in women. However, these associations became non-significant after adjustment for including BMI for each gender. The fully-adjusted hazard ratios (95%CI) were 1.43 (0.94 -2.18) in men and 1.24 (0.77-1.99) in women. Conclusion: Subjects with elevated leptin levels have a higher risk of CHF. The study supports the hypothesis that the influence of leptin level on risk of CHF may be through a pathway related to increasing BMI.

Rapid high-performance liquid chromatographic determination with fluorescence detection of furosemide in human body fluids and its confirmation by gas chromatography-mass spectrometry.

Furosemide (FD: Lasix) is a loop diuretic which strongly increases both urine flow and electrolyte urinary excretion. Healthy volunteers were administered 40 mg orally (dissolved in water) and concentrations of FD were determined in serum and urine for up to 6 h for eight subjects, who absorbed water at a rate of 400 ml/h. Quantification was performed by HPLC with fluorescence detection (excitation at 233 nm, emission at 389 nm) with a limit of detection of 5 ng/ml for a 300-microliters sample. The elution of FD was completed within 4 min using a gradient of acetonitrile concentration rising from 30 to 50% in 0.08 M phosphoric acid. The delay to the peak serum concentration ranged from 60 to 120 min. FD was still easily measurable in the sera from all subjects 6 h after administration. In urine, the excretion rates reached their maximum between 1 and 3 h. The total amount of FD excreted in the urine averaged 11.2 mg (range 7.6-14.0 mg), with a mean urine volume of 3024 ml (range 2620-3596 ml). Moreover, the urine density was lower than 1.010 (recommended as an upper limit in doping analysis to screen diuretics) only for 2 h. An additional volunteer was administered 40 mg of FD and his urine was collected over a longer period. FD was still detectable 48 h after intake. Gas chromatography-mass spectrometry with different types of ionization was used to confirm the occurrence of FD after permethylation of the extract. Negative-ion chemical ionization, with ammonia as reactant gas, was found to be the most sensitive method of detection.

Evaluation of a summary score of cognitive performance for use in trials in perioperative and critical care.

Background/Aims: Cognitive dysfunction after medical treatment is increasingly being recognized. Studies on this topic require repeated cognitive testing within a short time. However, with repeated testing, practice effects must be expected. We quantified practice effects in a demographically corrected summary score of a neuropsychological test battery repeatedly administered to healthy elderly volunteers. Methods: The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Neuropsychological Assessment Battery (for which a demographically corrected summary score was developed), phonemic fluency tests, and trail-making tests were administered in healthy volunteers aged 65 years or older on days 0, 7, and 90. This battery allows calculation of a demographically adjusted continuous summary score. Results: Significant practice effects were observed in the CERAD total score and in the word list (learning and recall) subtest. Based on these volunteer data, we developed a threshold for diagnosis of postoperative cognitive dysfunction (POCD) with the CERAD total score. Conclusion: Practice effects with repeated administration of neuropsychological tests must be accounted for in the interpretation of such tests. Ignoring practice effects may lead to an underestimation of POCD. The usefulness of the proposed demographically adjusted continuous score for cognitive function will have to be tested prospectively in patients.

Role of the c-Jun N-terminal Kinase signaling in pancreatic β-cells

L'insuline est une hormone qui diminue la concentration de sucre dans le sang et qui est produite par la cellule β du pancréas. Un défaut de production de cette hormone est une des causes principales du diabète. Cette perte de production d'insuline est la conséquence à la fois, de la réduction du nombre de cellules β et du mauvais fonctionnement des cellules β restantes. L'inflammation, en activant la voie de signalisation «c-Jun N-terminal Kinase» (JNK) contribue au déclin de ces cellules. Cette voie de signalisation est activée par des protéines telles que des kinases qui reçoivent le signal de stress. Dans ce travail de thèse nous nous sommes intéressés à étudier le rôle de «Dual leucine zipper bearing kinase» (DLK) comme protéine capable de relayer le stress inflammatoire vers l'activation de la voie JNK dans les cellules β-pancréatiques. Nous montrons que DLK est présente dans les cellules β-pancréatiques et qu'elle agit effectivement comme un activateur de la voie de signalisation de JNK. En outre, DLK joue un rôle clé dans le contrôle de l'expression de l'insuline, de la sécrétion de l'insuline en réponse au glucose et au maintien de la survie des cellules β. Si l'expression de cette protéine diminue, la cellule produit moins d'insuline et sera plus sensible à la mort en réponse au stress inflammatoire. A l'inverse si l'expression de DLK est augmentée, la cellule β produit et secrète plus d'insuline. Des variations de l'expression de DLK sont par ailleurs, associées à l'état de santé de la cellule β. Chez la ratte en gestation ou la souris obèse, dans lesquelles la cellule β produit plus d'insuline, l'expression de DLK est augmentée. En revanche dans les cellules β des patients diabétiques, l'expression de DLK est diminuée par rapport aux cellules non malades. En résumé, DLK est nécessaire pour le bon fonctionnement de la cellule β-pancréatique et son expression corrèle avec le degré de santé des cellules, faisant que cette protéine pourrait être une cible thérapeutique potentiel. Les cellules β-pancréatiques ont la capacité de réguler la sécrétion d'insuline en s'adaptant précisément au stimulus et à la glycémie. La fonction de la cellule β est cruciale dans l'homéostasie du glucose puisque sa dysfonction et sa mort mènent au développement des diabètes de type 1 et 2. De nombreuses études suggèrent que l'inflammation pourrait avoir un rôle dans la dysfonction et la destruction de ces cellules dans le diabète de type 2. L'excès chronique de cytokines proinflammatoires accélère le dysfonctionnement de la cellule β pancréatique par un mécanisme qui implique la voie de signalisation «c-Jun N-terminal Kinase» (JNK). L'activation de cette voie est organisée par des protéines d'échafaudages. Elle se fait par trois étapes successives de phosphorylation impliquant une «Mitogen Activated Protein Kinase Kinase Kinase» (MAP3K), une MAP2K et JNK. Dans ce travail de thèse nous montrons l'expression abondante et spécifique de la MAP3K «Dual Leucine Zipper Bearing Kinase» (DLK) dans les cellules β pancréatiques. Cela est la conséquence de l'absence du répresseur transcriptionnel «Repressor Element 1 Silencing Transcription». Nous montrons également que DLK régule l'activation de JNK et qu'il s'avère nécessaire pour la fonction et la survie de la cellule β pancréatique par un mécanisme impliquant le facteur de transcription PDX-1. L'invalidation de l'expression de DLK diminue l'expression de l'insuline et potentialise l'apoptose induite par des cytokines proinflammatoires. A l'inverse, la surexpression de DLK augmente l'expression et la sécrétion d'insuline induites par le glucose. Par conséquent des niveaux d'expression appropriés de DLK sont déterminants pour la fonction et la survie de la cellule β pancréatique. L'obésité et la grossesse sont caractérisées par une hyperinsulinémie qui résulte d'une augmentation de la production et de la sécrétion de l'insuline. L'expression de DLK est augmentée dans des îlots de rattes gestantes et des souris obèses comparés à leurs contrôles respectifs. A l'inverse, dans des sujets diabétiques, l'expression de DLK est diminuée. Ensemble ces résultats montrent l'importance de DLK dans l'adaptation des îlots par un mécanisme qui pourrait impliquer la voie de signalisation de JNK. Des défauts dans cette voie régulée par DLK pourraient contribuer au dysfonctionnement et la mort de la cellule β pancréatique et par conséquent au développement du diabète. L'étude détaillée du mécanisme par lequel DLK active la voie de signalisation JNK et régule la fonction de la cellule β pancréatique pourrait ouvrir la voie des nouvelles thérapies ciblant l'amélioration de la fonction de la cellule β dans le diabète. - Pancreatic β-cells are evidently plastic in their ability to regulate insulin secretion. The quantity of insulin released by these cells varies according to the stimulus, and the prevailing glucose concentration, β-cell function is pivotal in glucose homeostasis, as their dysfunction, and death can lead to development of type 1 and type 2 diabetes. There are numerous reports so far underlying the role of inflammation in dysfunction, and destruction of β-cells, in both type 1 and type 2 diabetes. Chronic excess of pro¬inflammatory cytokines promotes a β-cell decline, via induction of the c-Jun N-terminal Kinase (JNK) pathway. The activation of the JNK pathway is organized by a scaffold protein-mediated module in which, a three-step phosphorylation cascade occurs. The latter includes, Mitogen activated protein kinase kinase kinase (MAP3K), MAP2K and JNK. In this thesis, we unveil that the MAP3K Dual Leucine Zipper Bearing Kinase (DLK) is selectively, and highly expressed in pancreatic β-cells, as the result from the absence of the transcriptional repressor named, Repressor Element 1 Silencing Transcription (REST). We show that DLK regulates activation of JNK, and is required for β-cell function and survival by modulating the PDX-1 transcription factor. Silencing of DLK expression diminishes insulin expression, and potentiated cytokine-mediated apoptosis. Conversely, overexpression of DLK increased insulin expression, and glucose-induced insulin secretion. Therefore, an appropriate level of DLK is critical for β-cell function and survival. Obesity and pregnancy are characterized by hyperinsulinemia resulting from an increased production and secretion of insulin. In isolated islets of pregnant rats, and obese mice, the expression of DLK was elevated when compared to their respective controls. However, decreased expression of DLK was observed in islets of individuals with diabetes. Taken together, we highlight the importance of DLK in islet adaptation, and describe a mechanism that may involve the JNK signaling. Deficiency in the JNK pathway regulated by DLK may contribute to β-cell failure and death, and thereby development of diabetes. Unraveling the mechanism whereby DLK activates the JNK pathway, and β-cell function, may pave the way for the design of novel therapies, aiming to improve β-cell function and survival in diabetes in general.

The anabolic androgenic steroid fluoxymesterone inhibits 11β-hydroxysteroid dehydrogenase 2-dependent glucocorticoid inactivation.

Anabolic androgenic steroids (AAS) are testosterone derivatives used either clinically, in elite sports, or for body shaping with the goal to increase muscle size and strength. Clinically developed compounds and nonclinically tested designer steroids often marketed as food supplements are widely used. Despite the considerable evidence for various adverse effects of AAS use, the underlying molecular mechanisms are insufficiently understood. Here, we investigated whether some AAS, as a result of a lack of target selectivity, might inhibit 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2)-dependent inactivation of glucocorticoids. Using recombinant human 11β-HSD2, we observed inhibitory effects for several AAS. Whereas oxymetholone, oxymesterone, danazol, and testosterone showed medium inhibitory potential, fluoxymesterone was a potent inhibitor of human 11β-HSD2 (half-maximal inhibitory concentration [IC(50)] of 60-100nM in cell lysates; IC(50) of 160nM in intact SW-620, and 530nM in MCF-7 cells). Measurements with rat kidney microsomes and lysates of cells expressing recombinant mouse 11β-HSD2 revealed much weaker inhibition by the AAS tested, indicating that the adverse effects of AAS-dependent 11β-HSD2 inhibition cannot be investigated in rats and mice. Furthermore, we provide evidence that fluoxymesterone is metabolized to 11-oxofluoxymesterone by human 11β-HSD2. Structural modeling revealed similar binding modes for fluoxymesterone and cortisol, supporting a competitive mode of inhibition of 11β-HSD2-dependent cortisol oxidation by this AAS. No direct modulation of mineralocorticoid receptor (MR) function was observed. Thus, 11β-HSD2 inhibition by fluoxymesterone may cause cortisol-induced MR activation, thereby leading to electrolyte disturbances and contributing to the development of hypertension and cardiovascular disease.

A critical edition of Joseph Conrad's "Because of the dollars" (Within the Tides, 1915)

Cette thèse de doctorat, écrite en anglais, propose la première édition critique de « Because of the Dollars », une nouvelle de l'écrivain anglais Joseph Conrad publiée dans le volume Within the Tides, en février 1915. Outre le texte critique de la nouvelle - le seul à ce jour reconstruit d'après une minutieuse étude des relations entre toutes les versions existantes - la présente édition offre aussi un vaste apparat éditorial. Le texte de la présente édition est éclectique. Sa ponctuation est essentiellement basée sur un texte proche du manuscrit de l'auteur, et donc non corrompu par le processus de transmission. Mais ses mots sont tirés des dernières versions révisées par l'auteur, étant donné qu'au cours de la transmission, les mots, contrairement aux marques de ponctuation, n'ont pas été contaminés. Le résultat de cette méthode est un texte reflétant, tant pour les mots que pour la ponctuation, les choix de l'auteur. L'apparat éditorial sert à placer la nouvelle dans la vie de Conrad, tracer l'évolution du texte, et offrir au lecteur des informations historiques et culturelles qui permettront une meilleure lecture de l'oeuvre. Cet apparat est composé de quatre parties : une introduction, une étude sur les textes de la nouvelle, une collation historique de toutes les variantes, et des notes explicatives. L'introduction place l'oeuvre dans le contexte de la vie de l'écrivain, en donne la réception critique de 1915 à nos jours, et en éclaire le contexte historique (un changement de monnaie à Singapour en 1903-4). L'étude sur les textes trace le développement et la transmission du texte, depuis son inscription sur pages manuscrites jusqu'à sa publication dans les oeuvres complètes de Conrad. La collation historique inventorie toutes les variantes textuelles entre les différentes versions existantes. Enfin, les notes explicatives glosent les allusions littéraires, historiques, et culturelles du texte. « Because of the Dollars » et Within the Tides n'ayant attiré que très peu d'attention critique, les informations contenues dans cet apparat éditorial sont complètement inédites, et jettent une lumière originale sur une période peu étudiée de la vie de Conrad.

Catabolite repression in Pseudomonas aeruginosa PAO1 regulates the uptake of C4 -dicarboxylates depending on succinate concentration.

In Pseudomonas aeruginosa carbon catabolite repression (CCR) is exerted by the CbrA/B-CrcZ-Crc global regulatory system. Crc is a translational repressor that, in the presence of preferred carbon sources, such as C4 -dicarboxylates, impairs the utilization of less preferred substrates. When non-preferred substrates are present, the CrcZ sRNA levels increase leading to Crc capture, thereby allowing growth of the bacterium at the expense of the non-preferred substrates. The C4 -dicarboxylate transport (Dct) system in P. aeruginosa is composed of two main transporters: DctA, more efficient at mM succinate concentrations, and DctPQM, more important at μM. In this study, we demonstrate that the Dct transporters are differentially regulated by Crc, depending on the concentration of succinate. At high concentrations, Crc positively regulates the expression of the dctA transporter gene and negatively regulates dctPQM post-transcriptionally. The activation of dctA is explained by a Crc-mediated repression of dctR, encoding a transcriptional repressor of dctA. At low succinate concentrations, Crc regulation is impaired. In this condition, CrcZ levels are higher and therefore more Crc proteins are sequestered, decreasing the amount of Crc available to perform CCR on dctR and dctPQM. As a result, expression of dctA is reduced and that of dctPQM is increased.

An optimized method for establishing high purity murine CD8+ T cell cultures.

Establishing CD8(+) T cell cultures has been empirical and the published methods have been largely individual laboratory based. In this study, we optimized culturing conditions and show that IL-2 concentration is the most critical factor for the success of establishing CD8(+) T cell cultures. High IL-2 concentration encouraged T cells to non-specifically proliferate, express a B cell marker, B220, and undergo apoptosis. These cells also lose typical irregular T cell morphology and are incapable of sustaining long-term cultures. Using tetramer and intracellular cytokine assessments, we further demonstrated that many antigen-specific T cells have been rendered nonfunctional when expanded under high IL-2 concentration. When IL-2 is used in the correct range, B220-mediated cell depletion greatly enhanced the success rate of such T cell cultures.

Large-scale imatinib dose-concentration-effect study in CML patients under routine care conditions.

This observational study analyzed imatinib pharmacokinetics and response in 2478 chronic myeloid leukemia (CML) patients. Data were obtained through centralized therapeutic drug monitoring (TDM) at median treatment duration of ≥2 years. First, individual initial trough concentrations under 400mg/day imatinib starting dose were estimated. Second, their correlation (C^min(400mg)) with reported treatment response was verified. Low imatinib levels were predicted in young male patients and those receiving P-gp/CYP3A4 inducers. These patients had also lower response rates (7% lower 18-months MMR in male, 17% lower 1-year CCyR in young patients, Kaplan-Meier estimates). Time-point independent multivariate regression confirmed a correlation of individual C^min(400mg) with response and adverse events. Possibly due to confounding factors (e.g. dose modifications, patient selection bias), the relationship seemed however flatter than previously reported from prospective controlled studies. Nonetheless, these observational results strongly suggest that a subgroup of patients could benefit from early dosage optimization assisted by TDM, because of lower imatinib concentrations and lower response rates.

A drug administration decision support system

Drug delivery is one of the most common clinical routines in hospitals, and is critical to patients' health and recovery. It includes a decision making process in which a medical doctor decides the amount (dose) and frequency (dose interval) on the basis of a set of available patients' feature data and the doctor's clinical experience (a priori adaptation). This process can be computerized in order to make the prescription procedure in a fast, objective, inexpensive, non-invasive and accurate way. This paper proposes a Drug Administration Decision Support System (DADSS) to help clinicians/patients with the initial dose computing. The system is based on a Support Vector Machine (SVM) algorithm for estimation of the potential drug concentration in the blood of a patient, from which a best combination of dose and dose interval is selected at the level of a DSS. The addition of the RANdom SAmple Consensus (RANSAC) technique enhances the prediction accuracy by selecting inliers for SVM modeling. Experiments are performed for the drug imatinib case study which shows more than 40% improvement in the prediction accuracy compared with previous works. An important extension to the patient features' data is also proposed in this paper.

Segmental bioelectrical impedance analysis to assess perioperative fluid changes.

OBJECTIVES: Perioperative fluid accumulation determination is a challenge for the clinician. Bioelectrical impedance analysis (BIA) is a noninvasive method based on the electrical properties of tissues, which can assess body fluid compartments. The study aimed at assessing their changes in three types of surgery (thoracic, abdominal, and intracranial) requiring various regimens of fluid administration. DESIGN: Prospective descriptive trial. PATIENTS: A total of 26 patients scheduled for elective surgery were separated into three groups according to site of surgery: thoracic (n = 8), abdominal aortic (n = 8), and brain surgery (n = 10). SETTING: University teaching hospital. INTERVENTION: None. MEASUREMENTS: Whole body, segmental (arm, trunk, and legs) BIA at multiple frequency (0.5, 50, 100 kHz) was used to assess perioperative fluid accumulation after surgery. The fluid balances were calculated from the charts. RESULTS: The patients were aged 62+/-4 yrs. Fluid balances were 4.8+/-1.0 L, 4.1+/-0.5 L, and 1.9+/-0.3 L, respectively, in the three groups. In trunk surgery patients, fluid accumulation was detected as a drop in impedance in the operated area at all frequencies. In the operated area, there was an expansion of both intra- and extracellular compartments. A reduction in high frequencies' impedance in the legs was only detected after aortic surgery. Fluid accumulation and trunk impedance changes were strongly correlated. Neurosurgery only induced minor body fluid changes. CONCLUSIONS: Segmental BIA is able to detect and localize perioperative fluid accumulation. It may become a bedside tool to quantify and to localize fluid accumulation.

Developmental critical period in gentic redox dysregulation: animal and human studies in schizophrenia

Converging evidence favors an abnormal susceptibility to oxidative stress in schizophrenia. Decreased levels of glutathione (GSH), the major cellular antioxidant and redox regulator, was observed in cerebrospinal-fluid and prefrontal cortex of patients. Importantly, abnormal GSH synthesis of genetic origin was observed: Two case-control studies showed an association with a GAG trinucleotide repeat (TNR) polymorphism in the GSH key synthesizing enzyme glutamate-cysteine-ligase (GCL) catalytic subunit (GCLC) gene. The most common TNR genotype 7/7 was more frequent in controls, whereas the rarest TNR genotype 8/8 was three times more frequent in patients. The disease associated genotypes (35% of patients) correlated with decreased GCLC protein, GCL activity and GSH content. Similar GSH system anomalies were observed in early psychosis patients. Such redox dysregulation combined with environmental stressors at specific developmental stages could underlie structural and functional connectivity anomalies. In pharmacological and knock-out (KO) models, GSH deficit induces anomalies analogous to those reported in patients. (a) morphology: spine density and GABA-parvalbumine immunoreactivity (PV-I) were decreased in anterior cingulate cortex. KO mice showed delayed cortical PV-I at PD10. This effect is exacerbated in mice with increased DA from PD5-10. KO mice exhibit cortical impairment in myelin and perineuronal net known to modulate PV connectivity. (b) physiology: In cultured neurons, NMDA response are depressed by D2 activation. In hippocampus, NMDA-dependent synaptic plasticity is impaired and kainate induced g-oscillations are reduced in parallel to PV-I. (c) cognition: low GSH models show increased sensitivity to stress, hyperactivity, abnormal object recognition, olfactory integration and social behavior. In a clinical study, GSH precursor N-acetyl cysteine (NAC) as add on therapy, improves the negative symptoms and decreases the side effects of antipsychotics. In an auditory oddball paradigm, NAC improves the mismatched negativity, an evoked potential related to pre-attention and to NMDA receptors function. In summary, clinical and experimental evidence converge to demonstrate that a genetically induced dysregulation of GSH synthesis combined with environmental insults in early development represent a major risk factor contributing to the development of schizophrenia Conclusion Based on these data, we proposed a model for PSIP1 promoter activity involving a complex interplay between yet undefined regulatory elements to modulate gene expression.

Study design for technology assessment: critical issues.

The epidemiological methods have become useful tools for the assessment of the effectiveness and safety of health care technologies. The experimental methods, namely the randomized controlled trials (RCT), give the best evidence of the effect of a technology. However, the ethical issues and the very nature of the intervention under study sometimes make it difficult to carry out an RCT. Therefore, quasi-experimental and non-experimental study designs are also applied. The critical issues concerning these designs are discussed. The results of evaluative studies are of importance for decision-makers in health policy. The measurements of the impact of a medical technology should go beyond a statement of its effectiveness, because the essential outcome of an intervention or programme is the health status and quality of life of the individuals and populations concerned.