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The influence of inhaled multi-walled carbon nanotubes on the autonomic nervous system.

ABSTRACT: Heart rate and cardiovascular function are regulated by the autonomic nervous system. Heart rate variability (HRV) as a marker reflects the activity of autonomic nervous system. The prognostic significance of HRV in cardiovascular disease has been reported in clinical and epidemiological studies. The present study focused on the influence of inhaled multi-walled carbon nanotubes (MWCNTs) on autonomic nervous system by HRV analysis.Male Sprague-Dawley rats were pre-implanted with a telemetry device and kept in the individual cages for recovery. At week four after device implantation, rats were exposed to MWCNTs for 5 h at a concentration of 5 mg/m(3). The real-time EKGs were recorded by a telemetry system at pre-exposure, during exposure, 1 day and 7 days post-exposure. HRV was measured by root mean square of successive differences (RMSSD); the standard deviation of inter-beat (RR) interval (SDNN); the percentage of successive RR interval differences greater than 5 ms (pNN5) and 10 ms (pNN10); low frequency (LF) and high frequency (HF).Exposure to MWCNTs increased the percentage of differences between adjacent R-R intervals over 10 ms (pNN10) (p < 0.01), RMSSD (p < 0.01), LF (p < 0.05) and HF (p < 0.01).Inhalation of MWCNTs significantly alters the balance between sympathetic and parasympathetic nervous system. Whether such transient alterations in autonomic nervous performance would alter cardiovascular function and raise the risk of cardiovascular events in people with pre-existing cardiovascular conditions warrants further study.

SUBMITTER: Zheng W

PROVIDER: S-EPMC4750189 | biostudies-other | 2016 Feb

REPOSITORIES: biostudies-other

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Project description:Multi-walled carbon nanotubes (MWCNTs) are among the most promising nanomaterials because of their physical and chemical properties. However, since they are biopersistent fiber-like materials which share similarities with asbestos, concerns have arisen about their health effects. With their various industrial usages, occupational exposure to MWCNTs may occur mainly by inhalation as these nanomaterials can get aerosolised. The number of toxicological studies on CNTs has steadily increased for the last decades. Different works showed that MWCNT exposure by inhalation or intratracheal instillation could lead to pulmonary toxicity, such as lung inflammation, genotoxicity, fibrosis or lung cancer (Kasai et al. 2015, Kasai et al. 2016, Porter et al. 2013, Suzui et al. 2016). To date, only one MWCNT (MWNT-7) has been classified as possibly carcinogen to human (Group 2B) while the others have not been as classifiable as to their carcinogenicity to humans (Group 3) because of the lack of data on their carcinogenic potential (IARC 2017). Because of the wide variety of CNTs with various length, diameter or functionalisation, additional effort is required to assess their pulmonary toxicity. As a complementary approach to conventional toxicological assays, the omics methods are useful technologies for the mechanistic understanding of the toxicological effects observed following exposure to chemicals and particulate matters. Importantly, they can also be used as predictive tools for identifying the mode of action of other particles with similar physical and chemical characteristics. These molecular approaches may also be used for the discovery of exposure markers or early markers of adverse effects, before the appearance of clinical signs of a disease (Rahman et al. 2017). Several studies assessed gene expression alteration following in vivo exposure to CNTs (Poulsen et al. 2015, Snyder-Talkington et al. 2013, Ellinger-Ziegelbauer and Pauluhn 2009). These omics approaches were used to identify genes and pathways modulated in response to exposure. However, there are still too few studies to assess the link between MWCNT physico-chemical properties, global gene or protein expression profiles, and long-term effects. In a previous study, we showed that inhalation of two pristine MWCNTs, the long and thick NM-401, and the short and thin NM-403, induced alveolar neutrophilic granulocyte influx, a hallmark of inflammation, which was proportional to the lung CNT BET surface deposited dose (Gate et al. 2019). However, due to their different physical and chemical properties, one could assume that these two CNTs may have diverse toxicological profiles, but the conventional toxicology approaches used in this early work were probably not sensitive enough to identify such differences. In order to gain additional insight about their toxicological properties, in the current study, we compare the alteration induced by the two MWCNTs on the transcriptome in the lung tissue and the proteome in the broncho-alveolar lavage fluid (BALF) after rat exposure by inhalation. The omics analyses were performed from 3 days up to 180 days.

Project description:The studies focusing on magnesium oxychloride cement (MOC) composites have recently become fairly widespread because of MOC's excellent mechanical properties and environmental sustainability. Numerous fillers, admixtures and nano-dopants were studied in order to improve the overall performance of MOC-based derivatives. Some of them exhibited specific flaws, such as a tendency to aggregate, increase in porosity, aeration of the composite matrix, depreciation in water resistance and mechanical strength, etc. In this manuscript, MOC-based composites doped by multi-walled carbon nanotubes (MWCNTs) are designed and tested. In order to modify the final properties of composites, diatomite was admixed as partial substitution of MgO, which was used in the composition of the researched material in excess, i.e., the majority of MgO constituted part of MOC and the rest served as fine filler. The composites were subjected to the broad experimental campaign that covered SEM (scanning electron microscopy), EDS (energy dispersive spectroscopy), HR-TEM (high-resolution transmission electron microscopy), XRD (X-ray diffraction), OM (optical microscopy) and STA-MS (simultaneous thermal analysis with mass spectroscopy). For 28 days hardened samples, macrostructural and microstructural parameters, mechanical properties, hygric and thermal characteristics were experimentally assessed. The incorporation of MWCNTs and diatomite resulted in the significant enhancement of composites' compactness, mechanical strength and stiffness and reduction in water absorption and rate of water imbibition. The thermal properties of the enriched MOC composites yielded interesting values and provided information for future modification of thermal performance of MOC composites with respect to their specific use in practice, e.g., in passive moderation of indoor climate. The combination of MWCNTs and diatomite represents a valuable modification of the MOC matrix and can be further exploited in the design and development of advanced building materials and components.

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The influence of inhaled multi-walled carbon nanotubes on the autonomic nervous system.

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