Workers exposed to wood dust have an increased micronucleus frequency in nasal and buccal cells: results from a pilot study

Wood dust is recognised as a human carcinogen, based on the strong association of wood dust exposure and the elevated risk of malignant tumours of the nasal cavity and paranasal sinuses [sino-nasal cancer (SNC)]. The study aimed to assess genetic damage in workers exposed to wood dust using biomarkers in both buccal and nasal cells that reflect genome instability events, cellular proliferation and cell death frequencies. Nasal and buccal epithelial cells were collected from 31 parquet layers, installers, carpenters and furniture workers (exposed group) and 19 non-exposed workers located in Switzerland. Micronucleus (MN) frequencies were scored in nasal and buccal cells collected among woodworkers. Other nuclear anomalies in buccal cells were measured through the use of the buccal micronucleus cytome assay. MN frequencies in nasal and buccal cells were significantly higher in the exposed group compared to the non-exposed group; odds ratio for nasal cells 3.1 [95% confidence interval (CI) 1.8-5.1] and buccal cells 1.8 (95% CI 1.3-2.4). The exposed group had higher frequencies of cells with nuclear buds, karyorrhectic, pyknotic, karyolytic cells and a decrease in the frequency of basal, binucleated and condensed cells compared to the non-exposed group. Our study confirms that woodworkers have an elevated risk for chromosomal instability in cells of the aerodigestive tract. The MN assay in nasal cells may become a relevant biomonitoring tool in the future for early detection of SNC risk. Future studies should seek to standardise the protocol for MN frequency in nasal cells similar to that for MN in buccal cells.

Adding tobacco to cannabis: its frequency and likely implications.

INTRODUCTION: Young cannabis users are at increased risk of later cigarette initiation and progression to nicotine addiction. The present study addresses the frequency at which mulling (adding tobacco to cannabis smoked as joints) is performed and in which way this practice varies according to cigarette smoking status. METHODS: Data were issued from the Swiss 2007 European School Survey Project on Alcohol and other Drugs (ESPAD). A total of 881 past month cannabis users (mean age 15 years, boys 60.1%) were inquired on mulling using an anonymous self-administered questionnaire. Participants were further grouped according to their cigarette smoking status (daily, occasional, former, and never-smokers). RESULTS: Four of every 5 cannabis users depicted mulling as frequently performed. The highest occurrence was found among daily cigarette smokers (DSC; 90.3%), while former cigarette smokers reported the lowest (58.9%). The multinomial logistic regression showed DSC more likely reporting mulling as frequent compared with never-smokers (risk ratio = 3.56 [95% CI 1.55-8.21]). Conclusions: Mulling appears to be a very common process among young cannabis users, especially among concomitant cigarette smokers. Nevertheless, the majority of cigarette abstainers also reported frequently adding tobacco to the cannabis they smoke. Because it may represent a significant exposition to nicotine, mulling should be taken into account when assessing substance use among adolescents and in supporting their quitting attempts.

Pre-stimulus beta oscillations within left posterior sylvian regions impact auditory temporal order judgment accuracy.

Both neural and behavioral responses to stimuli are influenced by the state of the brain immediately preceding their presentation, notably by pre-stimulus oscillatory activity. Using frequency analysis of high-density electroencephalogram coupled with source estimations, the present study investigated the role of pre-stimulus oscillatory activity in auditory spatial temporal order judgments (TOJ). Oscillations within the beta range (i.e. 18-23Hz) were significantly stronger before accurate than inaccurate TOJ trials. Distributed source estimations identified bilateral posterior sylvian regions as the principal contributors to pre-stimulus beta oscillations. Activity within the left posterior sylvian region was significantly stronger before accurate than inaccurate TOJ trials. We discuss our results in terms of a modulation of sensory gating mechanisms mediated by beta activity.

Consequences of gestational stress on GABAergic modulation of respiratory activity in developing newborn pups.

The GABAergic system modulates respiratory activity and undergoes substantial changes during early life. Because this maturation process is sensitive to stress, we tested the hypothesis that gestational stress (GS) alters development of GABAergic modulation of respiratory control in rat pups. The respiratory responses to the selective GABAA receptor agonist muscimol were compared between pups born to dams subjected to GS (bright light and predator odor; 20 min/day from G9 to G19) or maintained under standard (control) conditions. Respiratory activity was measured on 1 and 4 days old pups of both sexes using in vivo (whole body plethysmography) and in vitro (isolated brainstem-spinal cord preparation) approaches. In intact pups, muscimol injection (0.75 mg/kg; i.p.) depressed minute ventilation; this response was less in GS pups, and at P4, muscimol augmented minute ventilation in GS females. Bath application of muscimol (0.01-0.5 μM) onto brainstem preparations decreased inspiratory (C4) burst frequency and amplitude in a dose-dependent manner; the responsiveness decreased with age. However, GS had limited effects on these results. We conclude that the results obtained in vivo are consistent with our hypothesis and show that GS delays maturation of GABAergic modulation of respiratory activity. The differences in the results observed between experimental approaches (in vivo versus in vitro) indicate that the effect of prenatal stress on maturation of GABAergic modulation of respiratory control mainly affects the peripheral/metabolic components of the respiratory control system.

Decrease in luteinizing hormone pulse frequency during a five-hour peripheral Ghrelin infusion in the ovariectomized rhesus monkey

RESUME : La ghrelin est un peptide sécrété par l'estomac jouant un rôle important dans le maintien de l'homéostasie énergétique. Ses taux plasmatiques sont augmentés durant des périodes prolongées de déficit nutritionnel. Une carence énergétique étant souvent associée à une inhibition de l'axe hypothalamo-hypophyso-ovarien, nous avons postulé que l'augmentation des taux circulant de ghrelin pourrait diminuer l'activité du générateur hypothalamique de pulsations de GnRH. Le protocole expérimental impliquait des singes rhésus adultes ovariectomisés (n=6) qui dans un premier temps recevaient durant 3 heures une perfusion de solution saline physiologique afin de mesurer la sécrétion pulsatile de LH à l'état basai. L'expérience se poursuivait alors durant 5 heures par une perfusion intraveineuse de ghrelin humaine (un bolus de 100-150µg suivi par 100-150µg/h) ou le maintien de la perfusion de solution saline physiologique. Des échantillons de sang étaient prélevés toutes les 15 minutes. La perfusion de ghrelin a augmenté ses taux plasmatiques de 2.9 fois par rapport aux valeurs de base. L'administration de ghrelin a significativement diminué la fréquence des pulsations de LH (de 0.89±0.07/h à l'état basai à 0.57±0.10/h durant la perfusion de ghrelin; p<0.05, moyenne±SEM), alors que la fréquence des pulsations de LH est restée inchangée durant la perfusion de solution physiologique. L'amplitude des pulsations de LH n'a pas été modifiée. La ghrelin a également stimulé de manière significative la sécrétion de cortisol et d'hormone de croissance, mais n'a toutefois pas eu d'effet sur la sécrétion de leptin. En conclusion, la ghrelin peut inhiber l'activité du générateur de pulsations de GnRH et pourrait ainsi contribuer à l'inhibition de l'axe de la reproduction observée durant des périodes de carence nutritionnelle, comme notamment chez les patientes souffrant d'anorexie mentale. La ghrelin peut également activer l'axe hypothalamo-hypophyso-surrénalien. Le lien dans cette situation entre l'activation de l'axe surrénalien et l'inhibition de l'axe de la reproduction reste à démontrer. ABSTRACT: Ghrelin, a nutrition-related peptide secreted by the stomach, is elevated during prolonged food deprivation. Because undernutrition is often associated with a suppressed reproductive axis, we have postulated that increasing peripheral ghrelin levels will decrease the activity of the GnRH pulse generator. Adult ovariectomized rhesus monkeys (n = 6) were subjected to a 5-h iv human ghrelin (100- to 150µg bolus followed by 100-150 µg/h) or saline infusion, preceded by a 3-h saline infusion to establish baseline pulsatile LH release. Blood samples were collected at 15-min intervals throughout the experiment. Ghrelin infusion increased plasma ghrelin levels 2.9-fold of baseline. Ghrelin significantly decreased LH pulse frequency (from 0.89 ± 0.07/h in baseline to 0.57 ± 0.10/h during ghrelin infusion; P<0.05, mean ± SEM), whereas LH pulse frequency remained unchanged during saline treatment. LH pulse amplitude was not affected. Ghrelin also significantly stimulated both Cortisol and GH release, but had no effect on leptin. We conclude that ghrelin can inhibit GnRH pulse activity and may thereby mediate the suppression of the reproductive system observed in conditions of undernutrition, such as in anorexia nervosa. Ghrelin also activates the adrenal axis, but the relevance of this to the inhibition of GnRH pulse frequency remains to be established.

High capacity audio watermarking using the high frequency band of the wavelet domain

This paper proposes a novel high capacity robust audio watermarking algorithm by using the high frequency band of the wavelet decomposition at which the human auditory system (HAS) is not very sensitive to alteration. The main idea is to divide the high frequency band into frames and, for embedding, to change the wavelet samples depending on the average of relevant frame¿s samples. The experimental results show that the method has a very high capacity (about 11,000 bps), without significant perceptual distortion (ODG in [¿1 ,0] and SNR about 30dB), and provides robustness against common audio signal processing such as additive noise, filtering, echo and MPEG compression (MP3).

Monitoring of noninvasive ventilation by built-in software of home bilevel ventilators: a bench study.

BACKGROUND: Current bilevel positive-pressure ventilators for home noninvasive ventilation (NIV) provide physicians with software that records items important for patient monitoring, such as compliance, tidal volume (Vt), and leaks. However, to our knowledge, the validity of this information has not yet been independently assessed. METHODS: Testing was done for seven home ventilators on a bench model adapted to simulate NIV and generate unintentional leaks (ie, other than of the mask exhalation valve). Five levels of leaks were simulated using a computer-driven solenoid valve (0-60 L/min) at different levels of inspiratory pressure (15 and 25 cm H(2)O) and at a fixed expiratory pressure (5 cm H(2)O), for a total of 10 conditions. Bench data were compared with results retrieved from ventilator software for leaks and Vt. RESULTS: For assessing leaks, three of the devices tested were highly reliable, with a small bias (0.3-0.9 L/min), narrow limits of agreement (LA), and high correlations (R(2), 0.993-0.997) when comparing ventilator software and bench results; conversely, for four ventilators, bias ranged from -6.0 L/min to -25.9 L/min, exceeding -10 L/min for two devices, with wide LA and lower correlations (R(2), 0.70-0.98). Bias for leaks increased markedly with the importance of leaks in three devices. Vt was underestimated by all devices, and bias (range, 66-236 mL) increased with higher insufflation pressures. Only two devices had a bias < 100 mL, with all testing conditions considered. CONCLUSIONS: Physicians monitoring patients who use home ventilation must be aware of differences in the estimation of leaks and Vt by ventilator software. Also, leaks are reported in different ways according to the device used.

Feeding rate and frequency on juvenile pompano growth

The objective of this work was to evaluate the ideal feeding rate and frequency for juvenile pompano (Trachinotus marginatus). Two experiments were carried out in a completely randomized design, with three replicates each. In experiment I, 25 fish (4.8±0.6 g and 6.48±0.01 cm) were stocked in 15 tanks (50 L) during 21 days and fed 4, 8, 12, 16, and 20% body weight per day. In experiment II, 20 fish (4.1±0.1 g and 6.6±0.1 cm) were stocked in 15 tanks (40 L) during 28 days and fed 2, 6, 8, and 10 times a day. The tested feeding rates and frequencies did not influence survival. Final weight and length in experiment I were significantly lower in fish fed 4% body weight per day, whereas in experiment II only weight was significantly lower in fish fed 2 and 6 times a day. At the end of both experiments, apparent feed conversion showed significant difference, with the worst value observed for fish fed 20% body weight per day in experiment I and 2 times a day in experiment II. Juvenile pompano show better growth performance when fed 8% body weight per day and 8 times a day.

Spatial processing for frequency diversity schemes

A novel technique to obtain optimum blind spatialprocessing for frequency diversity spread spectrum (FDSS) communicationsystems is introduced. The sufficient statistics for alinear combiner, which prove ineffective due to the interferers frequencycharacteristics, are modified to yield improved detectionunder partial jamming in the spectral domain. Robustness to partialtime jamming is achieved by extending the notion of replicasover the frequency axis to a repetition over the time variable. Analysisand simulations are provided, showing the advantages of usingFDSS with spatial diversity to combat the interference when it isconfined to a narrow frequency band or short time interval relativeto the desired signal extent in either domain.

Positive time-frequency distributions based on joint marginal constraints

This correspondence studies the formulation of members ofthe Cohen-Posch class of positive time-frequency energy distributions.Minimization of cross-entropy measures with respect to different priorsand the case of no prior or maximum entropy were considered. It isconcluded that, in general, the information provided by the classicalmarginal constraints is very limited, and thus, the final distributionheavily depends on the prior distribution. To overcome this limitation,joint time and frequency marginals are derived based on a "directioninvariance" criterion on the time-frequency plane that are directly relatedto the fractional Fourier transform.

Performance of noninvasive ventilation algorithms on ICU ventilators during pressure support: a clinical study.

To evaluate the impact of noninvasive ventilation (NIV) algorithms available on intensive care unit ventilators on the incidence of patient-ventilator asynchrony in patients receiving NIV for acute respiratory failure. Prospective multicenter randomized cross-over study. Intensive care units in three university hospitals. Patients consecutively admitted to the ICU and treated by NIV with an ICU ventilator were included. Airway pressure, flow and surface diaphragmatic electromyography were recorded continuously during two 30-min periods, with the NIV (NIV+) or without the NIV algorithm (NIV0). Asynchrony events, the asynchrony index (AI) and a specific asynchrony index influenced by leaks (AIleaks) were determined from tracing analysis. Sixty-five patients were included. With and without the NIV algorithm, respectively, auto-triggering was present in 14 (22%) and 10 (15%) patients, ineffective breaths in 15 (23%) and 5 (8%) (p = 0.004), late cycling in 11 (17%) and 5 (8%) (p = 0.003), premature cycling in 22 (34%) and 21 (32%), and double triggering in 3 (5%) and 6 (9%). The mean number of asynchronies influenced by leaks was significantly reduced by the NIV algorithm (p < 0.05). A significant correlation was found between the magnitude of leaks and AIleaks when the NIV algorithm was not activated (p = 0.03). The global AI remained unchanged, mainly because on some ventilators with the NIV algorithm premature cycling occurs. In acute respiratory failure, NIV algorithms provided by ICU ventilators can reduce the incidence of asynchronies because of leaks, thus confirming bench test results, but some of these algorithms can generate premature cycling.

Patient-ventilator asynchrony during noninvasive pressure support ventilation and neurally adjusted ventilatory assist in infants and children.

OBJECTIVES: To document the prevalence of asynchrony events during noninvasive ventilation in pressure support in infants and in children and to compare the results with neurally adjusted ventilatory assist. DESIGN: Prospective randomized cross-over study in children undergoing noninvasive ventilation. SETTING: The study was performed in a PICU. PATIENTS: From 4 weeks to 5 years. INTERVENTIONS: Two consecutive ventilation periods (pressure support and neurally adjusted ventilatory assist) were applied in random order. During pressure support (PS), three levels of expiratory trigger (ETS) setting were compared: initial ETS (PSinit), and ETS value decreased and increased by 15%. Of the three sessions, the period allowing for the lowest number of asynchrony events was defined as PSbest. Neurally adjusted ventilator assist level was adjusted to match the maximum airway pressure during PSinit. Positive end-expiratory pressure was the same during pressure support and neurally adjusted ventilator assist. Asynchrony events, trigger delay, and cycling-off delay were quantified for each period. RESULTS: Six infants and children were studied. Trigger delay was lower with neurally adjusted ventilator assist versus PSinit and PSbest (61 ms [56-79] vs 149 ms [134-180] and 146 ms [101-162]; p = 0.001 and 0.02, respectively). Inspiratory time in excess showed a trend to be shorter during pressure support versus neurally adjusted ventilator assist. Main asynchrony events during PSinit were autotriggering (4.8/min [1.7-12]), ineffective efforts (9.9/min [1.7-18]), and premature cycling (6.3/min [3.2-18.7]). Premature cycling (3.4/min [1.1-7.7]) was less frequent during PSbest versus PSinit (p = 0.059). The asynchrony index was significantly lower during PSbest versus PSinit (40% [28-65] vs 65.5% [42-76], p < 0.001). With neurally adjusted ventilator assist, all types of asynchronies except double triggering were reduced. The asynchrony index was lower with neurally adjusted ventilator assist (2.3% [0.7-5] vs PSinit and PSbest, p < 0.05 for both comparisons). CONCLUSION: Asynchrony events are frequent during noninvasive ventilation with pressure support in infants and in children despite adjusting the cycling-off criterion. Compared with pressure support, neurally adjusted ventilator assist allows improving patient-ventilator synchrony by reducing trigger delay and the number of asynchrony events. Further studies should determine the clinical impact of these findings.

Evolution of gene expression changes in newborn rats after mechanical ventilation with reversible intubation

Résumant mon travail de thèse, l'article qui suit décrit un nouveau modèle animal servant à étudier l'impact combiné d'une ventilation mécanique (VM), d'une oxygénothérapie et d'une inflammation sur des poumons immatures. Cette étude permet, pour la première fois, de mesurer l'expression de gènes à distance d'une VM pour en analyser la cinétique. La VM représente un traitement intégral dans la prise en charge de prématurés. Sauvant des vies, elle est cependant non-physiologique et décrite comme nocive à court et à long terme, empêchant le bon développement pulmonaire. Nombreuses études se sont intéressées à l'impact immédiat de la VM sur les poumons, mais il n'existe à ce jour aucun modèle de rongeur pour en analyser les effets tardifs. Par analogie avec la clinique, nous avons créé un modèle avec un animal dont le stade développemental pulmonaire est comparable aux prématurés humains et consistant en une oxygénothérapie, une VM modérée avec intubation non chirurgicale, similaire à la pratique quotidienne, et un contexte inflammatoire mimant celui de chorioamnionite dans lequel bien des prématurés naissent. Nous avons ensuite réalisé une extubation pour permettre une période de rétablissement, puis fait des analyses et sur le plan structurel par histologie conventionnelle et en 3D, et sur le plan biologique, par analyse de l'expression de gènes et de protéines. Ce travail a permis de valider ce nouveau modèle comme outil de recherche pour réaliser des mesures à distance d'une VM chez des rats nouveau-nés. Comparant ces mesures à celles prises à la fin de la VM, nous observons: une augmentation initiale et transitoire des médiateurs impliqués dans la cascade inflammatoire dont le corrélat histologique est une maladie inflammatoire pulmonaire et, tardivement, une altération plus développementale de la structure pulmonaire avec diminution de l'alvéolarisation. Ceci pourrait être en partie dû à une expression asynchrone de gènes décrits comme importants pour la formation des alvéoles (matrix metalloproteinase 9, elastine). Offrant une nouvelle approche pour la recherche pulmonaire chez les rongeurs, ce modèle servira comme futur outil pour approfondir nos connaissances de la physiopathologie conduisant aux altérations structurelles retrouvées dans les poumons d'anciens prématurés soumis à une VM (dysplasie broncho-pulmonaire), pour tester l'influence de certains traitements (p.ex. surfactant) et pour étudier les effets de la VM en l'appliquant à des modèles transgéniques.