Risk factors for mortality in patients with pulmonary infections with non-tuberculous mycobacteria: a retrospective cohort study.

BACKGROUND: Infections with non-tuberculous mycobacteria (NTM) represent an increasing problem. Their clinical relevance is still largely unknown as well as predictors for mortality in affected patients. The objective was to describe prevalence and clinical relevance of different NTM and to identify risk factors for mortality. METHODS: Retrospective cohort study of 124 patients with NTM detection between January 2001 and December 2011. Clinical characteristics like symptoms and radiological appearance were assessed at presentation. The primary outcome was all cause mortality during the follow-up period. Univariate and multivariate survival analyses using Cox proportional hazard models were employed for statistical analysis. RESULTS: Over the study period, the frequency of NTM isolation varied from 4 to 12 patients per year. Twenty-nine out of 124 patients (23%) had a clinically relevant infection, according to the criteria of the American Thoracic Society (ATS). Mycobacterium avium was isolated most frequently, but Mycobacterium kansasii, Mycobacterium malmoense and Mycobacterium xenopi had the highest clinical relevance. Symptoms were mostly diverse and non-specific. On radiology, cavities were observed more frequently than a nodular-bronchiectatic variant or consolidation. In 75% of all patients, follow up time was more than two years. Median survival was 6.5 years (95%CI = 2.7-10.3). Factors significantly influencing survival time were haemoptysis (HR = 0.2, 95%CI = 0.1-0.6) and a consolidation on imaging (HR = 5.1, 95%CI 1.4-18.2). CONCLUSIONS: The presentation of an infection with NTM can be diverse and depends mainly on the causative NTM pathogen. The most important predictor for increased mortality is the radiological appearance of a consolidation.

Hydrolyzed collagen improves bone status and prevents bone loss in ovariectomized C3H/HeN mice.

SUMMARY: This study evaluates the effect of hydrolyzed collagen (HC) on bone health of ovariectomized mice (OVX) at different ages. Twenty-six weeks after the OVX procedure, HC ingestion was still able to improve significantly bone mineral density (BMD) and some femur biomechanical parameters. Moreover, HC ingestion for 1 month before surgery prevented BMD decrease. INTRODUCTION: HC can play an important role in preserving BMD before osteoporosis appears. The aim of this study was to evaluate the effect of HC on bone health of ovariectomized mice at different ages. METHODS: Female C3H mice were either OVX at 3 or 6 months and fed for 6 months (first experiment) or 3 months (second experiment) with diet including 0, 10, or 25 g/kg of HC. In the second experiment, one group received HC 1 month before surgery, and two groups received the supplementation immediately after surgery, one fed ad libitum and the other by gavage. Mice treated with raloxifene were used as a positive control. BMD, femur intrinsic and extrinsic biomechanical properties, and type I collagen C-terminal telopeptide were measured after 12 and 26 weeks. Food intake and spontaneous physical activity were also recorded. RESULTS: The OVX procedure increased body weight, while food intake decreased, thus suggesting that resting metabolism was decreased. Ingestion of 25 g/kg of HC for 3 or 6 months reduced bone loss significantly in, respectively, 3- and 6-month-old OVX mice. The lowest HC concentration was less efficient. HC ingestion for 3 months is as efficient as raloxifene to protect 3-month-old OVX mice from bone loss. Our results also demonstrated that HC ingestion before surgery prevented the BMD decreases. CONCLUSION: This study confirms that dietary collagen reduces bone loss in OVX mice by increasing the diameter of the cortical areas of femurs and can have a preventive effect.

Inhibition of food intake induced by acute stress in rats is due to satiation effects.

Acute mild stress induces an inhibition of food intake in rats. In most studies, the cumulative daily food intake is measured but this only provides a quantitative assessment of ingestive behavior. The present study was designed to analyze the reduction in food intake induced by acute stress and to understand which behavioral and central mechanisms are responsible for it. Two different stressors, restraint stress (RS) and forced swimming stress (FSS), were applied acutely to male Wistar rats. We first measured corticosterone and ACTH in plasma samples collected immediately after acute RS and FSS in order to validate our stress models. We measured food intake after RS and FSS and determined meal patterns and behavioral satiety sequences. The expressions of CRF, NPY and POMC in the hypothalamus were also determined immediately after acute RS and FSS. The rise in corticosterone and ACTH levels after both acute RS and FSS validated our models. Furthermore, we showed that acute stress induced a reduction in cumulative food intake which lasted the whole day for RS but only for the first hour after FSS. For both stressors, this stress-induced food intake inhibition was explained by a decrease in meal size and duration, but there was no difference in ingestion speed. The behavioral satiety sequence was preserved after RS and FSS but grooming was markedly increased, which thus competed with, and could reduce, other behaviors, including eating. Lastly, we showed that RS induced an increase in hypothalamic POMC expression. These results suggest that acute stress may affect ingestive behavior by increasing satiation and to some extent by enhancing grooming, and this may be due to stimulation of the hypothalamic POMC neurons.

Peripherally injected cholecystokinin-induced neuronal activation is modified by dietary composition in mice.

The aim of this study was to investigate the effect of long-term nutrient intake on the central response to the anorexigenic gut hormone CCK. C57BL/6 mice were fed one of three diets for 6 weeks: standard high carbohydrate (HC), high fat (HF), or high protein (HP). Assessment of brain response to cholecystokinin (CCK) by manganese-enhanced MRI (MEMRI) showed a reduction in neuronal activity both in an appetite-related area (ventromedial nucleus of the hypothalamus) and areas associated with reward (nucleus accumbens and striatum) regardless of diet. When comparing diet effects, while the HF diet did not induce any change in activity, reductions in MEMRI-associated signal were found in the paraventricular nucleus (PVN) and lateral hypothalamic area (LHA) when comparing the HP to the HC diet. In addition, a significant interaction was found between CCK administration and the HF diet, shown by an increased activation in the PVN, which suggests a decrease the inhibiting action of CCK. Our results put forward that the long-term intake of an HP diet leads to a reduction in basal hypothalamic activation while a high-fat diet leads to desensitization to CCK-induced effects in the hypothalamus.

Alterations of lipid metabolism and gene expression in rat adipocytes during chronic olanzapine treatment.

Although antipsychotics are established drugs in schizophrenia treatment, they are admittedly known to induce side effects favoring the onset of obesity and worsening its complications. Despite potential involvement of histamine receptor antagonism, or of other neurotransmitter systems, the mechanism by which antipsychotic drugs increase body weight is not elucidated. The aim of the present study was to investigate whether chronic antipsychotic treatments can directly alter the regulation of two main functions of white adipose tissue: lipolysis and glucose utilization. The influence of a classical antipsychotic (haloperidol) was compared to that of two atypical antipsychotics, one known to favor weight gain (olanzapine), the other not (ziprasidone). Cell size, lipolytic capacity and glucose transport activity were determined in white adipocytes of rats subjected to 5-week oral treatment with these antipsychotics. Gene expression of adipocyte proteins involved in glucose transport or fat storage and mobilization, such as glucose transporters (GLUT1 and GLUT4), leptin, matrix metallo-proteinase-9 (MMP9), hormone-sensitive lipase (HSL) and fatty acid synthase (FAS) was also evaluated. Adipocytes from chronic olanzapine-treated rats exhibited decreased lipolytic activity, lowered HSL expression and increased FAS expression. These changes were concomitant to enlarged fat deposition and adipocyte size. Alterations were observed in adipocytes from olanzapine-treated rats whereas the other antipsychotics did not induce any notable disorder. Our results therefore show evidence of an effect of chronic antipsychotic treatment on rat adipocyte metabolism. Thus, impairment of fat cell lipolysis should be considered as a side effect of certain antipsychotics, leading, along with the already documented hyperphagia, to the excessive weight gain observed in patients under prolonged treatment..

Dysregulation of energy homeostasis in mice overexpressing insulin-like growth factor-binding protein 6 in the brain.

AIMS/HYPOTHESIS: IGFs, IGF receptors and IGF binding proteins (IGFBPs) are widely expressed in the central nervous system. To investigate the physiological significance of IGFBP-6 in the brain we established two transgenic mouse lines overexpressing human (h)-IGFBP-6 under the control of glial fibrillary acidic protein promoter. Increasing evidence suggests that insulin/IGF signalling pathways could be implicated in the neuroendocrine regulation of energy homeostasis. We explored the impact of brain IGFBP-6 overexpression on the regulation of food intake and energy balance. METHODS: Transgenic mice were fed either a control diet or a high-fat diet for up to 3 months. Glucose and insulin tolerance tests were carried out before and after the diet period. Plasma parameters (insulin, leptin, glucose, NEFAs and triglycerides) were measured, and uncoupling protein 1 (UCP-1) expression was quantified in brown adipose tissue. Oxygen consumption was also measured in both groups. RESULTS: The transgenic mice fed a high-fat diet for 3 months developed obesity, showing increases in plasma leptin, glucose and insulin levels and mild insulin resistance. As compared with wild-type mice, no significant differences were found in the quantity of food intake. However, UCP-1 expression was down-regulated in the brown adipose tissue of the transgenic mice. CONCLUSIONS/INTERPRETATION: Our results show that brain IGFBP-6 has an impact on the regulation of energy homeostasis. These transgenic h-IGFBP-6 mice may be considered a new tool for studies of the involvement of the brain IGF system in metabolism control and obesity.

A tryptophan-rich protein diet efficiently restores sleep after food deprivation in the rat.

Sleep depends on the quantity and quality of the diet. Several studies have shown that food deprivation results in a reduction in sleep duration. It has also been demonstrated that in the newborn, the supply of certain essential amino acids improves sleep through their action on the synthesis of specific neurotransmitters. The aim of the present study was to test if the quantity and/or quality of dietary protein could improve the recovery of sleep during re-feeding after caloric deprivation. Sleep parameters were compared in rats fed ad libitum, food restricted during 4 days, or reefed isocalorically after food restriction with three dietary regimens varying in terms of the amount (14% versus 30%) or quality (milk protein or alpha-lactalbumin) of protein. The results showed that sleep recovery, in particular slow-wave sleep, was improved in rats re-fed with alpha-lactalbumin. This result confirms the close relationship between feeding and sleep and suggest that alpha-lactabumin could be used to improve sleep in adult submitted to nutritional disturbances such as food restriction, shift work, Ramadan.

Fat-depleted CLA-treated mice enter torpor after a short period of fasting.

Resting energy expenditure (Resting-EE), EE with treadmill exercise, and post-prandial thermogenesis were continuously monitored by indirect calorimetry during a 24 h recording session in control (CT) and CLA-treated (CLA) (1% CLA in the food, by weight) C57Bl/6 male mice. After 15 days of CLA treatment, the fat content of CLA mice had fallen to 20% of that in CT mice. CLA mice were able to face the energy challenge of exercise but used less lipid than CT mice. Resting-EE values fell during the post-exercise period. The thermogenic response to a calibrated test meal given 5 h after the run abolished the differences in EE and substrate oxidation between CT and CLA mice. However, 2.5 h after ingestion of the test meal onward, CT mice gradually increased their lipid oxidation to sustain resting-EE levels. In contrast, CLA mice did not increase their lipid oxidation and their resting-EE levels fell significantly until they entered into torpor. Blood leptin was low but similar in CT and CLA-treated mice suggesting that leptin is not critical to induce torpor. We suggest that the durable inhibition of lipid oxidation in fasting CLA mice was an adaptive behaviour devoted at sparing the residual adipose deposits.

Efficient coherent combining of widely tunable fiber lasers.

We have experimentally demonstrated coherent combining of 2 and then 4 fiber lasers, with respectively 99% and 95% combining efficiency. The combining method investigated here is based on a multi-arm resonator of interferometric configuration. In spite of its interferometric nature, the multi-arm laser operates without significant power fluctuations, even in an unprotected environment. This occurs when the arm length difference is large enough to introduce spectral modulations of period smaller than the laser bandwidth. We have also experimentally shown that the combining method is compatible with wavelength tuning. A Mach- Zehnder Fiber Laser was tuned over a wide spectral range of 60nm. Theoretically then, we confirm that the combining method can be scaled to a large number of lasers without decreasing the combining efficiency.

Coumarin-like fluorescent molecular rotors for bioactive polymers probing.

Polysaccharides are interesting and often essential macromolecules but are difficult to analyse due to their lack of convenient chromophores. We propose an efficient labelling procedure for polysaccharides such as functionalized dextrans with coumarin derivatives: the fluorescent tracers present inter alia properties of emission of fluorescence dependent on the molecular environment (polarity, viscosity, temperature, pH, etc.). Hence, with in mind the understanding of cell-polysaccharide interactions, the labelled polymers were studied by in vitro tests on a line of endothelial cells sensitive to the proliferative effect of these dextran polysaccharides. Using 3D fluorescence microscopy, the fixation and internalization of fluorescent functionalized dextrans were observed in endothelial cells.

Feeding patterns and meal microstructure during development of a taste aversion to a threonine devoid diet.

Food intake decreases and a conditioned taste aversion is induced when rats are fed a diet that is devoid of an indispensable amino acid. The purpose of this study was to characterize the meal patterns associated with (1) the onset of anorexia after the initial recognition of a threonine deficiency and (2) after the development of the conditioned taste aversion to this deficient diet. When rats ate the threonine-devoid diet for the first time, meal patterns were characterized by an increase in intermeal interval (IMI) between 3 and 6 h after food presentation, which was followed by a decrease in meal size and ingestion rate, between 6 and 12 h. Meal patterns on days 2 and 10 were associated with expression of the taste aversion, characterized by meals of smaller size, longer duration and by a reduction in ingestion rate, without variations in either IMI or meal frequency. Meals of the threonine-deficient group were composed of more frequent bouts, smaller size and shorter duration, with large within-meal pauses, which accounted for the reduced ingestion rate. This study presents the first analysis in terms of feeding patterns and meal microstructure of a conditioned taste aversion induced by a food rather than a toxin.

Prediction of basal metabolism from organ size in the rat: relationship to strain, feeding, age, and obesity.

Use of the weight of various organs and tissues together with their specific metabolic activity for prediction of basal metabolism (BM) seems to be promising. In this study we compared the use of this method with those based on simple or multiple regression analyses. We observed that 97.4% of differences in BM in a group of nine adult male Wistar rats weighing 273--517 g could be accounted for by changes in tissue and organ weights. BM measured in lean Zucker and Sprague-Dawley rats did not diverge from the prediction of the model by >1.6%. According to the organ-based model as well as multiple regression analyses, but not simple regression analyses, BM was increased 18--21% in young rats, decreased 6--7% in food restricted/refed rats, and decreased 19--21% in aged rats. Only with obese rats did the predictions of the two methods diverge. The main reason for this discrepancy seems to be the way adipose tissue size and metabolism are taken into account.

A high-protein meal exceeds anabolic and catabolic capacities in rats adapted to a normal protein diet.

The postprandial fixation of dietary nitrogen in splanchnic and peripheral tissues as well as its dynamic transfer to the nitrogen pools of the body were quantified in rats subjected to an acute augmentation of dietary protein. For this purpose, we traced the dietary protein and studied the immediate fate of exogenous nitrogen in many tissues and biological fluids. Rats were adapted to a diet providing an adequate protein level (14 g/100 g), and then fed a meal containing either 0.42 g (Group A) or 1.50 g (Group H) of [(15)N]-labeled milk protein. The amounts of exogenous nitrogen transferred to urea (0.32 +/- 0.04 vs. 2.46 +/- 0.25 mmol, respectively), incorporated in splanchnic (0.41 +/- 0.02 vs. 0.87 +/- 0.10 mmol) and peripheral (1.65 +/- 0.84 vs. 2.36 +/- 0.49 mmol) tissue protein were higher in group H than in group A. Individual plasma amino acids (AA) [(15)N]-enrichments showed that AA respond differentially to an acute augmentation of dietary intake. This work provides new descriptive and quantitative information on the metabolic fate of dietary nitrogen in the postprandial state. It highlights the higher integration of a surplus of dietary nitrogen in the tissues even if it is rapidly limited by saturation of the protein synthesis capacities. The main metabolic response remains the stimulation of AA degradation, leading to a large rise in urea production. However, both anabolic and catabolic systems are exceeded, resulting in an elevation of peripheral AA and negative feedback on the gastric emptying rate.

Postprandial metabolism and aversive response in rats fed a threonine-devoid diet.

Lack of an indispensable amino acid in the diet induces a rapid reduction in food intake. In this study, we assessed whether the anorectic signal after ingestion of a meal lacking threonine originated from either direct perception of the decrease in plasma threonine or from an indirect effect related to increased postprandial amino acid catabolism and energy expenditure. We observed that 3 g of such a meal was sufficient to induce an aversive response to the diet within 2 h. Postprandial changes to plasma ammonia and urea, urinary urea, and energy metabolism did not differ from those measured after a control meal. In contrast, plasma threonine levels fell within 1 h after the meal. It is concluded that an increase in postprandial energy expenditure is not involved in the anorectic response to eating a threonine-devoid diet. The drop in plasma threonine levels may be a potential signal, but the fact that the decrease in food intake occurred 1 h after the decrease in plasma threonine questions a direct causal relationship.

Hindlimb immobilization applied to 21-day-old mdx mice prevents the occurrence of muscle degeneration.

Dystrophin-deficient skeletal muscles of mdx mice undergo their first rounds of degeneration-regeneration at the age of 14-28 days. This feature is thought to result from an increase in motor activity at weaning. In this study, we hypothesize that if the muscle is prevented from contracting, it will avoid the degenerative changes that normally occur. For this purpose, we developed a procedure of mechanical hindlimb immobilization in 3-wk-old mice to restrain soleus (Sol) and extensor digitorum longus (EDL) muscles in the stretched or shortened position. After a 14-day period of immobilization, the striking feature was the low percentage of regenerated (centronucleated) myofibers in Sol and EDL muscles, regardless of the length at which they were fixed, compared with those on the contralateral side (stretched Sol: 8.4 +/- 6.5 vs. 46.6 +/- 10.3%, P = 0.0008; shortened Sol: 1.2 +/- 1.6 vs. 50.4 +/- 16.4%, P = 0.0008; stretched EDL: 05 +/- 0.5 vs. 32.9 +/- 17.5%, P = 0. 002; shortened EDL: 3.3 +/- 3.1 vs. 34.7 +/- 11.1%, P = 0.002). Total numbers of myofibers did not change with immobilization. This study shows that limb immobilization prevents the occurrence of the first round of myofiber necrosis in mdx mice and suggests that muscle contractions play a role in the skeletal muscle degeneration of dystrophin-deficient mdx mouse muscles.

Rapid fall in plasma threonine followed by increased intermeal interval in response to first ingestion of a threonine-devoid diet in rats.

In most animals, ingestion of a diet lacking an essential amino acid (EAA) gives rise to anorexia within a few hours. The first signal in this feeding response may be the fall in plasma levels of the limiting EAA. In the present study, we measured plasma amino acid levels and food intake after the first exposure to either a threonine-devoid (THR-DEV) or corrected (COR) diet in 16 rats bearing a chronic jugular catheter for blood sampling. Food intake was reduced 165 min (p<0.05) after presentation of the THR-DEV diet. Analysis of the feeding pattern showed that intake was reduced via a four-fold lengthening of the second inter-meal interval. Plasma threonine levels started to fall between 30 and 60 min after onset of the meal (p<0.05). These results, observed in the same rats, lend further support for an early modification of the plasma amino acid pattern in relation to the decrease in feeding of a diet that is EAA deficient.

Substrate oxidation during exercise in the rat cannot fully account for training-induced changes in macronutrients selection.

This study investigated spontaneous dietary adaptation to regular exercise in relation to substrate oxidation measured during exercise. Male Wistar rats were offered permanent access to the three sources of macronutrients supplemented with minerals and vitamins. The rats remained sedentary or were trained daily during 3 weeks at moderate intensity (20 m x min(-1), 2 hours). Body weight, total caloric intake, and macronutrients selection were recorded throughout the experiment. Energy expenditure and substrate oxidation were measured before, during, and after an exercise identical for trained and untrained rats (10 m x min(-1) 1 hour). Training reduced body weight gain (2.27 v 5.57 g x day(-1)), increased protein intake (52.6% v 39.2%), and decreased carbohydrate intake (21.3% v 39.5%). Basal and running energy expenditure, as well as glucose and lipid oxidation, remained essentially comparable in trained and untrained rats. The relative contribution of glucose oxidation (Gox) to total energy expenditure decreased during exercise (52.2%, average of all rats) relative to before exercise (60.8%). Gox during exercise was positively correlated with resting Gox before exercise, showing that preexercise substrate oxidation was a strong determinant of running substrate oxidation. However, the slope was smaller for the trained than for the untrained rats, showing that exercise increases Gox less in trained rats than in untrained ones. We conclude from this study that, since food selection but not substrate oxidation changed following training, food intake adapted to substrate requirements induced by regular training and not the contrary. However, large differences remained between the mixture ingested, in which lipids accounted for only 26% of the energy, and the mixture oxidized during exercise, in which lipids accounted for 50.7% of the substrate oxidized. Such a difference may be related to metabolic requirements during the rest of the day and/or to the distribution of macronutrients intake relative to exercise. This question deserves further investigation with recording of macronutrients selection, energy expenditure, and substrate oxidation over 24 hours.

Early induction of angiotensin I-converting enzyme in rat carotid artery after balloon injury.

Several studies have demonstrated the effectiveness of angiotensin I-converting enzyme (ACE) inhibitors in preventing the neointima formation found after denudation of the rat carotid artery by balloon injury. The aim of the present study was to determine the role of ACE in this model and to compare the treatment with the ACE inhibitor ramiprilat with that with the angiotensin II antagonist HR 720. The endothelial layer of the left carotid artery was removed using an inflated balloon catheter. Injured and control vessels were both submitted to histomorphological analysis and DNA content quantification at 2, 4, 6, 8, 12, and 14 days after injury. Evaluation of neointima thickening demonstrated a slow but steady increase of neointima that was significant after day 6 and reached 30% of the lumen in 2 weeks. This was paralleled by an increase in DNA content, which was significant 4 days after injury. ACE mRNA levels were quantified by polymerase chain reaction after reverse transcription. Measurement of ACE mRNA levels revealed a significant upregulation 2 and 8 days after injury, with no significant difference when compared with control tissue at later time points. ACE activity was also significantly enhanced at 2 and 8 days after injury, with no significant difference when compared with control tissue at later time points. In addition, the treatment with ramiprilat was more efficient in reducing neointima formation than that with HR 720. These data underlie the role of ACE in this model of restenosis. The early induction of ACE expression after endothelial injury but before significant changes in the vessel structure suggests that ACE activity might be one of the mechanisms that trigger neointima formation in the rat.