Basal Ti level in the human placenta and meconium and evidence of a materno-foetal transfer of food-grade TiO2 nanoparticles in an ex vivo placental perfusion model.

BACKGROUND: Titanium dioxide (TiO2) is broadly used in common consumer goods, including as a food additive (E171 in Europe) for colouring and opacifying properties. The E171 additive contains TiO2 nanoparticles (NPs), part of them being absorbed in the intestine and accumulated in several systemic organs. Exposure to TiO2-NPs in rodents during pregnancy resulted in alteration of placental functions and a materno-foetal transfer of NPs, both with toxic effects on the foetus. However, no human data are available for pregnant women exposed to food-grade TiO2-NPs and their potential transfer to the foetus. In this study, human placentae collected at term from normal pregnancies and meconium (the first stool of newborns) from unpaired mothers/children were analysed using inductively coupled plasma mass spectrometry (ICP-MS) and scanning transmission electron microscopy (STEM) coupled to energy-dispersive X-ray (EDX) spectroscopy for their titanium (Ti) contents and for analysis of TiO2 particle deposition, respectively. Using an ex vivo placenta perfusion model, we also assessed the transplacental passage of food-grade TiO2 particles. RESULTS: By ICP-MS analysis, we evidenced the presence of Ti in all placentae (basal level ranging from 0.01 to 0.48 mg/kg of tissue) and in 50% of the meconium samples (0.02-1.50 mg/kg), suggesting a materno-foetal passage of Ti. STEM-EDX observation of the placental tissues confirmed the presence of TiO2-NPs in addition to iron (Fe), tin (Sn), aluminium (Al) and silicon (Si) as mixed or isolated particle deposits. TiO2 particles, as well as Si, Al, Fe and zinc (Zn) particles were also recovered in the meconium. In placenta perfusion experiments, confocal imaging and SEM-EDX analysis of foetal exudate confirmed a low transfer of food-grade TiO2 particles to the foetal side, which was barely quantifiable by ICP-MS. Diameter measurements showed that 70 to 100% of the TiO2 particles recovered in the foetal exudate were nanosized. CONCLUSIONS: Altogether, these results show a materno-foetal transfer of TiO2 particles during pregnancy, with food-grade TiO2 as a potential source for foetal exposure to NPs. These data emphasize the need for risk assessment of chronic exposure to TiO2-NPs during pregnancy.

Perinatal nicotine/smoking exposure and carotid chemoreceptors during development.

Tobacco smoking is still a common habit during pregnancy and is the most important preventable cause of many adverse perinatal outcomes. Prenatal smoking exposure can produce direct actions of nicotine in the fetus with the disruption of body and brain development, and actions on the maternal-fetal unit by causing repeated episodes of hypoxia and exposure to many toxic smoke products (such as carbon monoxide). Specifically, nicotine through binding to nicotinic acetylcholine receptors have ubiquitous effects and can affect carotid chemoreception development through structural, functional and neuroregulatory alterations of the neural circuits involved in the chemoafferent pathway, as well as by interfering with the postnatal resetting of the carotid bodies. Reduced carotid body chemosensitivity and tonic activity have thus been reported by the majority of the human and animal studies. This review focuses on the effects of perinatal exposure to tobacco smoke and nicotine on carotid chemoreceptor function during the developmental period. A description of the effects of smoking and nicotine on the control of breathing related to carotid body activity, and of the possible physiopathological mechanisms at the origin of these disturbances is presented.

Impact of nursing care on temperature environment in preterm newborns nursed in closed convective incubators.

AIMS: Very-low-birth-weight (VLBW) neonates require regular nursing procedures with frequent opening of the incubator resulting in a decrease in incubator air temperature. This study was designed to assess changes in the thermal status of VLBW neonates according to the type of nursing care and incubator openings. METHODS: Thirty-one VLBW neonates (mean gestational age: 28.7 ± 0.3 weeks of gestation) were included. Over a 10-day period, each opening of the incubator was recorded together with details about caregiving. Body temperature was recorded continuously, and door opening and closing events were recorded by a video camera. RESULTS: This study analysed 1,798 caregiving procedures with mean durations ranging from 6.2 ± 2.1 to 88.5 ± 33.4 min. Abdominal skin temperature decreased by up to 1.08°C/h for procedures such as tracheal intubation (p < 0.01). The temperature decrease was strongly correlated with the type of procedure (p < 0.01), incubator opening (p < 0.01) and procedure duration (p < 0.01). The procedure duration accounted for only 10% of the abdominal skin temperature change (p < 0.01). CONCLUSIONS: For VLBW neonates nursed in skin temperature servo-control incubators, the decrease in abdominal skin temperature during caregiving was correlated with the type of procedure, incubator opening modalities and procedure duration. These parameters should be considered to optimize the thermal management of VLBW neonates.

Histologic study of coronary, radial, ulnar, epigastric and internal thoracic arteries: application to coronary artery bypass grafts.

The biometry and the histology of coronary, radial, ulnar, epigastric and internal thoracic arteries were studied in order to investigate the cause of their occlusions in coronary bypass grafts and to improve the results of these bypass grafts. These various arteries were removed from 40 anatomical specimens (27 males and 13 females). We found a correlation between the internal calibers of the ulnar and coronary arteries in males. Intimal changes and the presence of atheromatous plaque were observed in coronary, radial and ulnar arteries, but never in the internal thoracic artery. Like coronary arteries and their branches, radial, ulnar and epigastric arteries are muscular arteries and ageing results in thickening of the intima, which becomes fibrotic with migration of myocytes from the media and duplication of the internal elastic lamina. The media becomes fibrous, hypertrophic or atrophic. In contrast, the internal thoracic artery is an elastic artery, like the aorta. Ageing is characterized by loss, over a variable extent, of one or several elastic laminae of the media and more marked intimal thickening. Although anatomically, the caliber of radial, ulnar, and epigastric arteries remains adapted to that of coronary arteries, the long-term patency of radial, ulnar and epigastric arteries used as grafts is related to their histological characteristics.

Peripheral chemoreceptor activity in sleeping neonates exposed to warm environments.

In neonates, it is often assumed that ventilatory control and heat stress interact. Thus the two factors have been implicated in various pathologies (apnoea, sudden infant death syndrome). However, little is known about the mechanisms of this interaction, and the influence of sleep is still debated. This study aimed at determining the influence of warm exposure on the decrease in ventilation during a hyperoxic test (HT), which is considered to be a measure of peripheral chemoreceptor activity. The test was performed in active (AS) and quiet sleep (QS) in 12 neonates exposed to thermoneutral or warm environments. The HT consisted of 30 s of inspired, 100% O(2). The ventilatory response was assessed in terms of a response time, defined as the time elapsing between HT onset and the first significant change in V(E). Our results show that, in both thermal conditions, the fall in V(E) was higher in AS than in QS. Warm exposure significantly enhanced the ventilatory response in AS (-27.5 +/- 8.7% vs. -38.3 +/- 8.8%, P < 0.01) but not in QS. A thermometabolic drive or inputs from thermoreceptors could be involved in the reinforcement of peripheral chemoreceptor activity in AS in warmer environments, which could contribute to an increasing risk of apnoea in neonates with altered chemoreceptor function. Since hypothalamic structures are involved in thermoregulatory, sleep processes and (probably) in respiratory control, it could well be the principal site where this interaction occurs.

Influence of incubator humidity on sleep and behaviour of neonates kept at stable body temperature.

UNLABELLED: The influence of incubator air humidity (via passive humidification through use of a water reservoir or via active humidification to 2 and 4 kPa) on sleep and behavioural changes was investigated in 13 neonates. The thermal environment of the incubator was servocontrolled via an interactive device tracking the skin temperature changes of the neonates. Using this servocontrolled skin temperature derivative heating programme, it is believed that an increase in air moisture content (reducing evaporative skin cooling) can be counterbalanced by a fall in neutral air temperature, so as to keep the body thermally constant. This procedure permits the experimental evaluation of the specific effect of air humidity on the thermal equilibrium air temperature and the thermal comfort of neonates without eliciting thermoregulatory mechanisms. Under the experimental conditions, in order to keep body temperature stable an increase in water vapour partial pressure from 1.72 (water reservoir) to 3.99 kPa (produced by a nebulizer) is counterbalanced by a decrease in air temperature of 1.49 degrees C. Within this humidity range, the air temperature must be lowered by 0.05 degrees C when the vapour pressure is increased by 0.08 kPa. The magnitude of this deviation depends on the humidity range and is probably a result of changes in the wetted skin area. CONCLUSION: When body temperature is kept constant, changes in air humidity do not modify sleep, body motility and respiratory and heart rates in neonates.