Application of intranasal dexmedetomidine in magnetic resonance imaging of preterm infants: The ED50, efficacy and safety analysis.

BACKGROUND: Infants undergoing magnetic resonance imaging (MRI) often require pharmacological sedation. Dexmedetomidine serves as a novel sedative agent that induces a unique unconsciousness similar to natural sleep, and therefore has currently been used as the first choice for sedation in infants and young children. OBJECTIVE: To determine the 50% effective dose (ED50) and 95% confidence interval (95%CI) of intranasal dexmedetomidine for MRI in preterm and term infants, and to observe the incidence of adverse events. To explore whether there were differences in ED50 and 95%CI, heart rate (HR) and blood oxygen saturation (SpO2), the induction time and wake-up time and the incidence of adverse events between the 2 groups, so as to provide guidance for clinical safe medication for the meanwhile. METHODS: A total of 68 infants were prospectively recruited for MRI examination under drug sedation (1 week ≤ age ≤ 23 weeks or weight ≤ 5kg). The children were divided into 2 groups according to whether they had preterm birth experience (Preterm group, Atterm group). The Dixon up-and-down method was used to explore ED50. The basic vital signs of the 2 groups were recorded, and the heart rate and SpO2 were recorded every 5 minutes until the infants were discharged from the hospital. The induction time, wake-up time and adverse events were recorded. RESULTS: The ED50 (95%CI) of intranasal dexmedetomidine in the Preterm group and the Atterm group were 2.23 (2.03-2.66) µg/kg and 2.64 (2.49-2.83) µg/kg, respectively (P < .05). the wake-up time was longer in Preterm group (98.00min) than in Atterm group (81.00 min) (P < .05), the incidence of bradycardia in Preterm group was 3/33, which was higher than that in Atterm group (1/35). There was no difference in the induction time between the 2 groups (P > .05), and there was no significant difference in other adverse events. CONCLUSIONS: Intranasal dexmedetomidine can be safely used for sedation in preterm infants undergoing MRI. Compared with term infants, preterm infants have a lower dose of dexmedetomidine, a higher incidence of bradycardia, and a longer weak-up time.

Effect of sulfasalazine on ferroptosis during intestinal injury in rats after liver transplantation.

Using a rat autologous orthotopic liver transplantation (AOLT) model and liver cold ischemia-reperfusion (I/R)-induced intestinal injury, we clarified whether ferroptosis occurred in rat AOLT cold I/R-induced intestinal injury. Additionally, the role and possible mechanism of the ferroptosis activator sulfasalazine (SAS) in intestinal injury-induced ferroptosis in rats with AOLT liver cold I/R were investigated. Sixty specific pathogen free (SPF)-grade adult male Sprague‒Dawley (SD) rats were randomly divided into 5 groups using the random number table method (n = 12). Six rats were randomly selected at 6 hour (h) and 24 h after I/R. Inferior vena cava blood specimens were collected from the portal vein (PV) opening at 6 h and 24 h. The concentrations of serum malondialdehyde (MDA), serum interleukin 6 (IL-6) were determined by enzyme-linked immunosorbent assay (ELISA). Ileal tissue was obtained from the PV opening in rats in each group at 6 h and 24 h, and ileal tissue sections were observed under light microscopy. The contents of intestinal MDA, superoxide dismutase (SOD), glutathione(GSH), glutathione peroxidase 4 (GPX4), and tissue iron were determined by ELISA, and the expression of GPX4 and the cysteine glutamate reverse transporter light chain protein (xCT) was determined by Western blot. The experimental results show that ferroptosis is involved in the pathophysiological process of intestinal injury induced by cold hepatic ischemia-reperfusion in AOLT rats. In addition, SAS (500 mg/kg) may inhibit the cystine/glutamate antiporters (System Xc¯)/GSH/GPX4 signal axis in intestinal injury induced by cold I/R in rat AOLT liver, or iron overload after reperfusion, causing a massive accumulation of L-ROS and activating cellular ferroptosis, further aggravate the intestinal injury.

MicroRNA-24 alleviates isoflurane-induced neurotoxicity in rat hippocampus via attenuation of oxidative stress.

Several miRNAs have been recently suggested as potential therapeutic targets for anesthesia-related diseases. This study was carried out to explore the biological roles of miR-24 in isoflurane-treated rat hippocampal neurons. Isoflurane was used to induce neurotoxicity in a rat model. Gain- and loss-of-function of miR-24 was performed, and the size and Ca2+ permeability of mitochondria, as well as cell proliferation and apoptosis, and levels of oxidative-stress-related factors were measured both in vivo and in vitro. Dual luciferase reporter gene assays were used to identify the target relationship between miR-24 and p27kip1. In this study, isoflurane treatment decreased miR-24 expression, after which, levels of neuron apoptosis and oxidative-stress-related factors were elevated and neuron viability was reduced. Over-expression of miR-24 inhibited oxidative damage and neuronal apoptosis in hippocampal tissues, and suppressed the size and Ca2+ permeability of mitochondria of hippocampal neurons. miR-24 enhanced the viability of rat hippocampal neurons by targeting p27kip1. To conclude, this study demonstrated that miR-24 attenuates isoflurane-induced neurotoxicity in rat hippocampus via its antioxidative properties and inhibiting p27kip1 expression.

Note: An in situ method for measuring the non-linear response of a Fabry-Perot cavity.

The transfer cavity is a very important frequency reference for laser stabilization and is widely used for applications such as precision measurements and laser cooling of ions or molecules. But the non-linear response of the piezoelectric ceramic transducer (PZT) in the Fabry-Perot cavity limits the performance of the laser stabilization. Thus, measuring and controlling such non-linearity is essential. Here we report an in situ, optical method to characterize this non-linearity by measuring the resonant signals of a dual-frequency laser. The differential measurement makes it insensitive to the laser and cavity drifts, while maintaining a very high sensitivity. It can be applied for various applications with PZTs, especially in an optical lab.