The origin of different bending stiffness between double-stranded RNA and DNA revealed by magnetic tweezers and simulations.

The subtle differences in the chemical structures of double-stranded (ds) RNA and DNA lead to significant variations in their biological roles and medical implications, largely due to their distinct biophysical properties, such as bending stiffness. Although it is well known that A-form dsRNA is stiffer than B-form dsDNA under physiological salt conditions, the underlying cause of this difference remains unclear. In this study, we employ high-precision magnetic-tweezer experiments along with molecular dynamics simulations and reveal that the relative bending stiffness between dsRNA and dsDNA is primarily determined by the structure- and salt-concentration-dependent ion distribution around their helical structures. At near-physiological salt conditions, dsRNA shows a sparser ion distribution surrounding its phosphate groups compared to dsDNA, causing its greater stiffness. However, at very high monovalent salt concentrations, phosphate groups in both dsRNA and dsDNA become fully neutralized by excess ions, resulting in a similar intrinsic bending persistence length of approximately 39 nm. This similarity in intrinsic bending stiffness of dsRNA and dsDNA is coupled to the analogous fluctuations in their total groove widths and further coupled to the similar fluctuation of base-pair inclination, despite their distinct A-form and B-form helical structures.

Universality in RNA and DNA deformations induced by salt, temperature change, stretching force, and protein binding.

Nucleic acid deformations play important roles in many biological processes. The physical understanding of nucleic acid deformation by environmental stimuli is limited due to the challenge in the precise measurement of RNA and DNA deformations and the complexity of interactions in RNA and DNA. Magnetic tweezers experiments provide an excellent opportunity to precisely measure DNA and RNA twist changes induced by environmental stimuli. In this work, we applied magnetic tweezers to measure double-stranded RNA twist changes induced by salt and temperature changes. We observed RNA unwinds when lowering salt concentration, or increasing temperature. Our molecular dynamics simulations revealed the mechanism: lowering salt concentration or increasing temperature enlarges RNA major groove width, which causes twist decrease through twist-groove coupling. Combining these results with previous results, we found some universality in RNA and DNA deformations induced by three different stimuli: salt change, temperature, and stretching force. For RNA, these stimuli first modify the major groove width, which is transduced into twist change through twist-groove coupling. For DNA, these stimuli first modify diameter, which is transduced into twist change through twist-diameter coupling. Twist-groove coupling and twist-diameter coupling appear to be utilized by protein binding to reduce DNA and RNA deformation energy cost upon protein binding.

5-Methyl-cytosine stabilizes DNA but hinders DNA hybridization revealed by magnetic tweezers and simulations.

5-Methyl-cytosine (5mC) is one of the most important DNA modifications and plays versatile biological roles. It is well known that 5mC stabilizes DNA duplexes. However, it remains unclear how 5mC affects the kinetics of DNA melting and hybridization. Here, we studied the kinetics of unzipping and rezipping using a 502-bp DNA hairpin by single-molecule magnetic tweezers. Under constant loading rates, 5mC increases the unzipping force but counterintuitively decreases the rezipping force at various salt and temperature conditions. Under constant forces, the non-methylated DNA hops between metastable states during unzipping and rezipping, which implies low energy barriers. Surprisingly, the 5mC DNA can't rezip after fully unzipping unless much lower forces are applied, where it rezips stochastically in a one-step manner, which implies 5mC kinetically hinders DNA hybridization and high energy barriers in DNA hybridization. All-atom molecular dynamics simulations reveal that the 5mC kinetically hinders DNA hybridization due to steric effects rather than electrostatic effects caused by the additional methyl groups of cytosines. Considering the possible high speed of DNA unzipping and zipping during replication and transcription, our findings provide new insights into the biological roles of 5mC.

Multivalent Cations Reverse the Twist-Stretch Coupling of RNA.

When stretched, both DNA and RNA duplexes change their twist angles through twist-stretch coupling. The coupling is negative for DNA but positive for RNA, which is not yet completely understood. Here, our magnetic tweezers experiments show that the coupling of RNA reverses from positive to negative by multivalent cations. Combining with the previously reported tension-induced negative-to-positive coupling reversal of DNA, we propose a unified mechanism of the couplings of both RNA and DNA based on molecular dynamics simulations. Two deformation pathways are competing when stretched: shrinking the radius causes positive couplings but widening the major groove causes negative couplings. For RNA whose major groove is clamped by multivalent cations and canonical DNA, their radii shrink when stretched, thus exhibiting positive couplings. For elongated DNA whose radius already shrinks to the minimum and canonical RNA, their major grooves are widened when stretched, thus exhibiting negative couplings.

Cytosine Methylation Enhances DNA Condensation Revealed by Equilibrium Measurements Using Magnetic Tweezers.

CpG methylation of DNA is common in mammalian cells. In sperm, the DNA has the highest level of CpG methylation and is condensed into toroidal structures. How CpG methylation affects DNA structures and interactions is important to understand its biological roles but is largely unknown. Using an RNA-DNA-RNA structure, we observed the equilibrium hopping dynamics between the condensed and extended states of DNA in the presence of polyamines or polylysine peptide as a reduced model of histone tails. Combing with the measured DNA elasticities, we report that CpG methylation of each cytosine nucleotide substantially increases DNA-DNA attraction by up to 0.2 kBT. For the DNA with 57% GC content, the relative increase caused by CpG methylation is up to 32% for the spermine-induced DNA-DNA attraction and up to 9% for the polylysine-induced DNA-DNA attraction. These findings help us to evaluate the energetic contributions of CpG methylation in sperm development and chromatin regulation.

Changes in plasma orexin-A levels in sevoflurane-remifentanil anesthesia in young and elderly patients undergoing elective lumbar surgery.

BACKGROUND: Delayed emergence from general anesthesia frequently occurs in elderly patients, but the reason is not clear. Orexin has been shown to be involved in arousal from general anesthesia. In this study, we examined plasma orexin-A levels in both elderly and young patients during the anesthesia arousal cycle. METHODS: We recruited 41 patients scheduled for elective lumbar surgery and eventually evaluated 34 patients. Patients were divided into a young group (age 30-55, N = 16) and an elderly group (age 65-77, N = 18). Anesthesia with sevoflurane-remifentanil was titrated to maintain the Bispectral Index between 45 and 65. The times from stopping anesthesia to eyes opening and extubation were recorded. Arterial blood was collected, and plasma orexin-A was determined by radioimmunoassay at the following 4 time points: preanesthesia (T0), 1 hour after anesthesia induction (T1), emergence (5 minutes after tracheal extubation) (T2), and 30 minutes after tracheal extubation (T3). RESULTS: The times from stopping anesthesia to eyes opening and tracheal extubation were both significantly longer in the elderly group than in the young group (P = 0.004, P = 0.01, respectively). Basal (T0) orexin-A levels were higher in the elderly group than in the young group (T0, 26.13 ± 1.25 vs 17.9 ± 1.30 pg/mL, P < 0.0001). Plasma orexin-A levels did not change during induction of anesthesia in either group but significantly increased at T2 (vs T0, P <0.0001) in both elderly (35.0 ± 1.7 pg/mL) and young (29.2 ± 1.9 pg/mL) groups. Orexin-A levels were significantly higher in the elderly than in the young group at T1, T2, and T3. CONCLUSION: Plasma orexin-A levels are not responsible for the delayed emergence from general anesthesia in elderly patients.

Hydrogen-rich saline improves survival and neurological outcome after cardiac arrest and cardiopulmonary resuscitation in rats.

BACKGROUND: Sudden cardiac arrest is a leading cause of death worldwide. Three-fourths of cardiac arrest patients die before hospital discharge or experience significant neurological damage. Hydrogen-rich saline, a portable, easily administered, and safe means of delivering hydrogen gas, can exert organ-protective effects through regulating oxidative stress, inflammation, and apoptosis. We designed this study to investigate whether hydrogen-rich saline treatment could improve survival and neurological outcome after cardiac arrest and cardiopulmonary resuscitation, and the mechanism responsible for this effect. METHODS: Sprague-Dawley rats were subjected to 8 minutes of cardiac arrest by asphyxia. Different doses of hydrogen-rich saline or normal saline were administered IV at 1 minute before cardiopulmonary resuscitation, followed by injections at 6 and 12 hours after restoration of spontaneous circulation, respectively. We assessed survival, neurological outcome, oxidative stress, inflammation biomarkers, and apoptosis. RESULTS: Hydrogen-rich saline treatment dose dependently improved survival and neurological function after cardiac arrest/resuscitation. Moreover, hydrogen-rich saline treatment dose dependently ameliorated brain injury after cardiac arrest/resuscitation, which was characterized by the increase of survival neurons in hippocampus CA1, reduction of brain edema in cortex and hippocampus, preservation of blood-brain barrier integrity, as well as the decrease of serum S100ß and neuron-specific enolase. Furthermore, we found that the beneficial effects of hydrogen-rich saline treatment were associated with decreased levels of oxidative products (8-iso-prostaglandin F2α and malondialdehyde) and inflammatory cytokines (tumor necrosis factor-α, interleukin-1ß, and high-mobility group box protein 1), as well as the increased activity of antioxidant enzymes (superoxide dismutase and catalase) in serum and brain tissues. In addition, hydrogen-rich saline treatment reduced caspase-3 activity in cortex and hippocampus after cardiac arrest/resuscitation. CONCLUSIONS: Hydrogen-rich saline treatment improved survival and neurological outcome after cardiac arrest/resuscitation in rats, which was partially mediated by reducing oxidative stress, inflammation, and apoptosis.

Potentiation of the lateral habenula-ventral tegmental area pathway underlines the susceptibility to depression in mice with chronic pain.

Chronic pain often develops severe mood changes such as depression. However, how chronic pain leads to depression remains elusive and the mechanisms determining individuals' responses to depression are largely unexplored. Here we found that depression-like behaviors could only be observed in 67.9% of mice with chronic neuropathic pain, leaving 32.1% of mice with depression resilience. We determined that the spike discharges of the ventral tegmental area (VTA)-projecting lateral habenula (LHb) glutamatergic (Glu) neurons were sequentially increased in sham, resilient and susceptible mice, which consequently inhibited VTA dopaminergic (DA) neurons through a LHbGlu-VTAGABA-VTADA circuit. Furthermore, the LHbGlu-VTADA excitatory inputs were dampened via GABAB receptors in a pre-synaptic manner. Regulation of LHb-VTA pathway largely affected the development of depressive symptoms caused by chronic pain. Our study thus identifies a pivotal role of the LHb-VTA pathway in coupling chronic pain with depression and highlights the activity-dependent contribution of LHbGlu-to-VTADA inhibition in depressive behavioral regulation.

The effects of different doses of estradiol (E2) on cerebral ischemia in an in vitro model of oxygen and glucose deprivation and reperfusion and in a rat model of middle carotid artery occlusion.

BACKGROUND: Because neuroprotective effects of estrogen remain controversial, we aimed to investigate the effect of different doses of estradiol (E2) on cerebral ischemia using both in vivo and in vitro experiments. RESULTS: PC12 cells were cultured at physiological (10 nM and 20 nM) or pharmacological (10 µM and 20 µM) dosages of E2 for 24 hours (h). The results of 5-bromodeoxyuridine (Brdu) incorporation and flow cytometric analysis showed that physiological doses of E2 enhanced cell proliferation and pharmacological doses of E2 inhibited cell proliferation. After the cells were exposed to oxygen and glucose deprivation (OGD) for 4 h and reperfusion for 20 h, the results of 3-(4, 5-dimethylthiazol-2-yl) 2, 5-diphenyl tetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release assay, flow cytometric analysis and Western blot analysis showed that physiological doses of E2 enhanced cell viability, reduced cell apoptosis and decreased the expression of pro-apoptotic protein caspase-3. In contrast, pharmacological doses of E2 decreased cell viability and induced cell apoptosis. In vivo, adult ovariectomized (OVX) female rats received continuous subcutaneous injection of different doses of E2 for 4 weeks. Transient cerebral ischemia was induced for 2 h using the middle cerebral artery occlusion (MCAO) technique, followed by 22 h of reperfusion. The results of Garcia test, 2, 3, 5-triphenyltetrazolium chloride (TTC) staining showed that 6 µg/kg and 20 µg/kg E2 replacement induced an increase in neurological deficit scores, a decrease in the infarct volume and a reduction in the expression of caspase-3 when compared to animals in the OVX group without E2 treatment. However, 50 µg/kg E2 replacement treatment decreased neurological deficit scores, increased the infarct volume and the expression of caspase-3 when compared to animals in the control group and 6 up/kg or 20 µg/kg E2 replacement group. CONCLUSION: We conclude that physiological levels of E2 exhibit neuroprotective effects on cerebral ischemia; whereas, pharmacological or supraphysiological doses of E2 have damaging effects on neurons after cerebral ischemia.

The protective roles of autophagy in ischemic preconditioning.

Autophagy, a process for the degradation of protein aggregates and dysfunctional organelles, is required for cellular homeostasis and cell survival in response to stress and is implicated in endogenous protection. Ischemic preconditioning is a brief and nonlethal episode of ischemia, confers protection against subsequent ischemia-reperfusion through the up-regulation of endogenous protective mechanisms. Emerging evidence shows that autophagy is associated with the protective effect of ischemic preconditioning. This review summarizes recent progress in research on the functions and regulations of the autophagy pathway in preconditioning-induced protection and cellular survival.

Orexin-A facilitates emergence from propofol anesthesia in the rat.

BACKGROUND: Hypothalamic orexinergic neurons play a critical role in the promotion and maintenance of wakefulness in mammals. Previous studies have demonstrated that activities of orexinergic neurons were inhibited by isoflurane and sevoflurane, and microinjection of orexin facilitated the emergence from volatile anesthesia. In this study we first examined the hypothesis that the activity of orexin neurons is inhibited by propofol anesthesia. Moreover, the role of the orexinergic signals in basal forebrain in regulating the anesthesia-arousal cycle of propofol anesthesia is also elucidated. METHODS: Rats were killed at 0, 30, 60, and 120 minutes of propofol infusion as well as at the time the righting reflex returned after the termination of anesthesia. Activated orexinergic neurons were detected by c-Fos expression. The plasma concentrations of orexin-A were measured by radioimmunoassay. Orexin-A (30 or 100 pmol) or the orexin-1 receptor antagonist, SB-334867A (5 or 20 µg), was microinjected into the basal forebrain 15 minutes before propofol infusion, or 15 minutes before the termination of propofol infusion. The loss and the return of the righting reflex time were recorded as the induction and the emergence time. RESULTS: Propofol anesthesia resulted in an inhibition of orexinergic neuron activity as demonstrated by the reduced numbers of c-Fos-immunoreactive orexinergic neurons. The activities of orexinergic neurons were restored when rats emerged from anesthesia. Propofol anesthesia decreased plasma orexin-A concentrations. Intrabasalis microinjection of orexin-A had no effect on the induction time but facilitated the emergence from propofol anesthesia. Inversely, intrabasalis microinjection of the orexin-1 receptor antagonist SB-334867A delayed the emergence from propofol anesthesia. CONCLUSIONS: Our findings indicate that activity of orexinergic neurons is inhibited by propofol anesthesia, and the orexin signals in basal forebrain are involved in anesthesia-arousal regulation from propofol anesthesia.

Anesthesia with sevoflurane and remifentanil under spontaneous respiration assisted with high-frequency jet ventilation for tracheobronchial foreign body removal in 586 children.

BACKGROUND: Foreign body aspiration is a common life-threatening event in young children. Tracheobronchial foreign body removal is usually performed by rigid tracheobronchoscopy under general anesthesia. Anesthetic and ventilation techniques vary greatly among anesthesiologists and institutions. In the present retrospective study, we report our anesthetic experience over 5 years. We describe complications and outcomes and analyze the clinical characteristics of anesthesia and ventilation. METHODS: We retrospectively reviewed relevant clinical findings of 586 pediatric patients treated with rigid tracheobronchoscopy under general anesthesia. All procedures were performed under inhaled sevoflurane anesthesia combined with remifentanil infusion, with spontaneous respiration assisted by high-frequency jet ventilation (HFJV) and topical airway anesthesia. RESULTS: Among 586 patients, the foreign body was successfully removed by rigid tracheobronchoscopy in 558 patients, and no foreign body was found in 28 patients. Laryngospasm was observed during the procedure in five patients. Hypoxemia was observed in 15 patients (2.6%). No severe complications or deaths occurred. The mean operation time was 22 min and the average hospital stay was 2 days. CONCLUSION: Inhaled sevoflurane anesthesia combined with remifentanil infusion, with spontaneous respiration assisted by HFJV and topical airway anesthesia, is safe and effective for tracheobronchial foreign body removal.

Neuroprotective effect of orexin-A is mediated by an increase of hypoxia-inducible factor-1 activity in rat.

BACKGROUND: Recent studies suggest that the novel neuropeptide orexin-A may play an essential role during neuronal damage. However, the function of orexin-A during brain ischemia remains unclear. Recently, hypoxia-inducible factor-1α (HIF-1α) was shown to be activated by orexin-A. The aim of the current study is to test the hypothesis that administration of exogenous orexin-A can attenuate ischemia-reperfusion injury through the facilitation of HIF-1α expression. METHODS: Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion for 120 min. Rats were treated with different doses of orexin-A or vehicle before the ischemia and at the onset of reperfusion. To investigate the action of HIF-1α in the neuroprotective effects of orexin-A, the HIF-1α inhibitor YC-1 was used alone or combined with orexin-A. Neurologic deficit scores and infarct volume were assessed. Brains were harvested for immunohistochemical staining and western blot analysis. RESULTS: Orexin-A significantly ameliorated neurologic deficit scores and reduced infarct volume after cerebral ischemia reperfusion. Administration of 30 µg/kg orexin-A showed optimal neuroprotective effects. This effect was still present 7 days after reperfusion. Furthermore, orexin-A decreased the number of apoptotic cells and significantly enhanced HIF-1α expression after cerebral ischemia reperfusion. Moreover, the facilitation of HIF-1α expression was accompanied with inhibition of von Hippel-Lindau expression. Administration of HIF-1α inhibitor suppressed the increase of HIF-1α and reversed the neuroprotective effects of orexin-A. CONCLUSIONS: Orexin-A has a neuroprotective effect against cerebral ischemia-reperfusion injury. These effects may be mediated through the HIF-1α pathway.

Multivalent Ion-Mediated Attraction between Like-Charged Colloidal Particles: Nonmonotonic Dependence on the Particle Charge.

Ion-mediated effective interactions are important for the structure and stability of charged particles such as colloids and nucleic acids. It has been known that the intrinsic electrostatic repulsion between like-charged particles can be modulated into effective attraction by multivalent ions. In this work, we examined the dependence of multivalent ion-mediated attraction between like-charged colloidal particles on the particle charge in a wide range by extensive Monte Carlo simulations. Our calculations show that for both divalent and trivalent salts, the effective attraction between like-charged colloidal particles becomes stronger with the increase of the particle charge, whereas it gradually becomes weakened when the particle charge exceeds a "critical" value. Correspondingly, as the particle charge is increased, the driving force for such effective attraction transits from an attractive electrostatic force to an attractive depletion force, and the attraction weakening by high particle charges is attributed to the transition of electrostatic force from attraction to repulsion. Our analyses suggest that the attractive depletion force and the repulsive electrostatic force at high particle charges result from the Coulomb depletion which suppresses the counterion condensation in the limited region between two like-charged colloidal particles. Moreover, our extensive calculations indicate that the "critical" particle charge decreases apparently for larger ions and smaller colloidal particles due to stronger Coulomb depletion and decreases slightly at higher salt concentrations due to the slightly enhanced Coulomb depletion in the intervening space between colloidal particles. Encouragingly, we derived an analytical formula for the "critical" particle charge based on the Lindemann melting law.

Comparison of two vasopressor protocols for preventing hypotension post-spinal anesthesia during cesarean section: a randomized controlled trial.

BACKGROUND: Norepinephrine infusion decreases hypotension after spinal anesthesia during cesarean section. This study aimed to compare the efficacy of norepinephrine infusion and ephedrine bolus against post-spinal hypotension in parturients. METHODS: In this double-blinded, randomized controlled clinical trial, parturients scheduled for elective cesarean section were randomly allocated to receive norepinephrine infusion (0.05 µg·kg-1·min-1) just before spinal anesthesia continuing for 30 min or ephedrine bolus (0.15 mg/kg) just before spinal anesthesia. A rescue bolus (5 µg norepinephrine for the norepinephrine group, and 5 mg ephedrine for the ephedrine group) was administered whenever hypotension occurred. Our primary outcome was the incidence of hypotension within 30 min of spinal anesthesia administration. Secondary outcomes included maternal and neonatal outcomes 30 min after spinal block, and neonatal cerebral oxygenation 10 min after birth. RESULTS: In total, 190 patients were enrolled; of these patients, 177 were included in the final analysis. Fewer patients suffered hypotension in the norepinephrine group than in the ephedrine group (29.5% vs. 44.9%, odds ratio [OR]: 0.51, 95% confidence interval [CI]: 0.28-0.95, P = 0.034). Moreover, the tachycardia frequency was lower in the norepinephrine group than in the ephedrine group (OR: 0.22, 95% CI: 0.11-0.44, P < 0.001), and patients suffered less nausea and vomiting (OR: 0.28, 95% CI: 0.11-0.70, P = 0.004). There was no difference in Apgar scores and umbilical arterial blood gas analysis between the two groups. However, neonatal cerebral regional saturations were significantly higher after birth in the norepinephrine group than in the ephedrine group (mean difference: 2.0%, 95% CI: 0.55%-3.45%, P = 0.008). CONCLUSION: In patients undergoing elective cesarean section with spinal anesthesia, norepinephrine infusion compared to ephedrine bolus resulted in less hypotension and tachycardia, and exhibited potential neonatal benefits. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02542748; https://clinicaltrials.gov/ct2/show/record/NCT02542748.

Limb remote ischemic preconditioning protects the spinal cord from ischemia-reperfusion injury: a newly identified nonneuronal but reactive oxygen species-dependent pathway.

BACKGROUND: It remains to be established whether spinal cord ischemic tolerance can be induced by limb remote ischemic preconditioning (RIPC), and the mechanisms underlying the neuroprotective effects of RIPC on the spinal cord need to be clarified. METHODS: Spinal cord ischemia was studied in New Zealand White rabbits. In experiment 1, all rabbits were subjected to 20-min spinal cord ischemia by aortic occlusion. Thirty minutes before ischemia, rabbits were subjected to sham intervention or RIPC achieved by bilateral femoral artery occlusion (10 min ischemia/10 min reperfusion, two cycles). Dimethylthiourea (500 mg/kg, intravenously), a hydroxyl radical scavenger, or vehicle was given 1 h before RIPC. Antioxidant enzyme activity was measured along with spinal cord histology and neurologic function. In experiment 2, rabbits were subjected to spinal cord ischemia, with or without RIPC. In addition, rabbits were pretreated with various doses of hexamethonium. RESULTS: RIPC improved neurologic function and reduced histologic damage. This was associated with increased endogenous antioxidant activity. Dimethylthiourea inhibited the protective effects of RIPC. In contrast, there was no effect of hexamethonium on the protective effect of RIPC. CONCLUSIONS: An initial oxidative stress acts as a trigger to upregulate antioxidant enzyme activity, rather than the neural pathway, and plays an important role in the formation of the tolerance against spinal cord ischemia by limb RIPC.

Isoflurane preconditioning induces neuroprotection by attenuating ubiquitin-conjugated protein aggregation in a mouse model of transient global cerebral ischemia.

BACKGROUND: In this study, we sought to clarify the role of inhibiting ubiquitin-conjugated protein aggregation in the formation of a neuroprotective effect after isoflurane preconditioning using a transient global cerebral ischemia-reperfusion injury mouse model. METHODS: C57BL/6 mice were randomly assigned to 3 groups (isoflurane preconditioning [IsoPC] group, control [Con] group, and sham group, n = 24 in each group). Mice in the IsoPC group and sham group were placed in a chamber and pretreated with isoflurane (1.2% isoflurane, 98% O(2), 1 hour/day) for 5 days. Mice in the Con group were placed in the same chamber but pretreated with oxygen only (98% O(2), 2% N(2), 1 hour/day) for 5 days. Twenty-four hours after the last preconditioning day, bilateral common carotid artery occlusion was performed as a model of global cerebral ischemia for 20 minutes in the IsoPC group and Con group. The total motor scores, number of viable neurons in the CA1 region of the hippocampus, and expression levels of conjugated ubiquitin or free ubiquitin were assessed by neurological assessment, immunohistochemistry, and Western blotting (at 24 and 72 hours) after reperfusion, respectively. RESULTS: The total motor scores in the IsoPC group were better than the Con group (P < 0.05). Morphological observations showed that the IsoPC group had better neuron structure than in the Con group. The numbers of viable neurons in the CA1 region were significantly increased by isoflurane preconditioning compared with those in the Con group (P < 0.05). The numbers of TUNEL-positive neurons in the CA1 region were significantly decreased after isoflurane preconditioning. The density of conjugated ubiquitin staining in the CA1 region of the IsoPC group was significantly lower than in the Con group (P < 0.05) and the expression of conjugated ubiquitin in the IsoPC group was lower than in the Con group (P < 0.05). CONCLUSION: Inhibition of ubiquitin-conjugated protein aggregation may have an essential role in inducing cerebral ischemic tolerance by isoflurane preconditioning in a transient global cerebral ischemia-reperfusion injury mouse model.

[Ischemic postconditioning induces neuroprotection via up-regulation of endogenous antioxidant enzyme activities: experiment with rabbits].

OBJECTIVE: To test the hypothesis that spinal cord protection induced by ischemic postconditioning is mediated by an increase of endogenous antioxidant enzyme activities during reperfusion phase in spinal cord. METHODS: Seventy-eight male New Zealand rabbits were randomly divided into 3 groups: Sham group (n = 18) undergoing sham operation without aortic occlusion; ischemia/reperfusion (I/R) group (n = 30) undergoing occlusion of the infrarenal abdominal aorta for 20 min, followed by reperfusion; and postconditioning (PostC) group (n = 30) undergoing occlusion of the infrarenal abdominal aorta for 20 min followed by 3 cycles of 30 s reperfusion/30 s ischemia just at the onset of reperfusion. 30 min, and 1, 3, 6, 24, and 48 h after reperfusion 5 rabbits from each group (and 3 from the Sham group) were killed with their spinal cords taken out, and spectrophotometric method was used to determine the antioxidant enzyme activity and malondialdehyde (MDA) content 6, 24, and 48 h after reperfusion motor function scoring of the hind limbs was conducted. RESULTS: (1) The motor function scores of the PostC group were significantly higher than those of the I/R group 6, 24, and 48 h after reperfusion (all P < 0.05). (2) The activities of superoxide dismutase (SOD) and catalase (CAT) in the spinal cord tissue of the PostC group 30 min-6 h after reperfusion were all significantly higher than those of the I/R group (all P < 0.05). There were no significant differences in the activity of glutathione peroxidase (GSH-px) at different time points between the PostC and I/R groups. (3) The MDA levels 24 h and 48 h after reperfusion of the PostC group were both significantly lower than that of the I/R group (both P < 0.01). CONCLUSION: Ischemic postconditioning shows effect against spinal cord ischemic-reperfusion injury mediated, at least partially, by up-regulating the activities of SOD and CAT in spinal cord during early reperfusion phase.

Effect of dual-acupoint and single-acupoint electric stimulation on postoperative outcomes in elderly patients subjected to gastrointestinal surgery: study protocol for a randomized controlled trial.

BACKGROUND: Transcutaneous electric acupoint stimulation (TEAS) has shown benefits when used peri-operatively. However, the role of numbers of areas with acupoint stimulation is still unclear. Therefore, we report the protocol of a randomized controlled trial of using TEAS in elderly patients subjected to gastrointestinal surgery, and comparing dual-acupoint and single-acupoint stimulation. METHODS/DESIGN: A multicenter, randomized, controlled, three-arm design, large-scale trial is currently undergoing in four hospitals in China. Three hundred and forty-five participants are randomly assigned to three groups in a 1:1:1 ratio, receiving dual-acupoint TEAS, single-acupoint TEAS, and no stimulation, respectively. The primary outcome is incidence of pulmonary complications at 30 days after surgery. The secondary outcomes include the incidence of pulmonary complications at 3 days after surgery; the all-cause mortality within 30 days and 1 year after surgery; admission to the intensive care unit (ICU) and length of ICU stay within 30 days after surgery; the length of postoperative hospital stay; and medical costs during hospitalization after surgery. DISCUSSION: The result of this trial (which will be available in September 2019) will confirm whether TEAS before and during anesthesia could alleviate the postoperative pulmonary complications after gastrointestinal surgery in elderly patients, and whether dual-acupoint stimulation is more effective than single-acupoint stimulation. TRIALS REGISTRATIONS: ClinicalTrials.gov, ID: NCT03230045 . Registered on 10 July 2017.

[Protective effect of remote ischemic preconditioning against focal cerebral ischemia/reperfusion injury in rats].

OBJECTIVE: To explore the effects of remote ischemic preconditioning (RIPC) on cerebral ischemia/reperfusion (I/R) injury. METHODS: Seventy male SD rats were randomly divided into seven groups (n=10 for each): (1) CONTROL GROUP: animals were subjected to I/R. (2)RIPC groups: RIPC was performed by 3 cycles of occlusion/reperfusion of bilateral femoral arteries for 5 minutes/5 minutes. According to the different intervals between RIPC and middle cerebral artery occlusion (MCAO), 6 RIPC subgroups were established: RIPC 30 minutes, 1, 2, 12, 24 and 48 hours subgroups, with intervals between RIPC and cerebral I/R of 30 minutes, 1, 2, 12, 24 and 48 hours respectively. The duration of MCAO was 120 minutes and reperfusion for 24 hours. The neurological dysfunction score (NDS) was evaluated at 24 hours after reperfusion. The infarction volume was then assessed with tetrazolium chloride (TTC) staining. RESULTS: The NDSs of RIPC 1, 2 and 24 hours groups were significantly lower than that of control group (all P<0.05), while with no significant differences of RIPC 30 minutes, 12 and 48 hours groups (all P>0.05). The area percentage of infarction in RIPC 1 hour [(17.9+/-7.5)%, P=0.016], RIPC 2 hours [(18.3+/-11.2)%, P=0.019] and RIPC 24 hours [(20.2+/-11.9)%, P=0.047] groups was significantly smaller than that in control group [(30.5+/-9.8)%], while no significant differences were observed in RIPC 30 minutes, 12 and 48 hours groups (all P>0.05). CONCLUSION: The RIPC the brain against focal cerebral I/R injury in rats, and the protection window is 1 to 2 hours after pretreatment and resumes after 24 hours.