Propofol protects against nitrosative stress-induced apoptotic insults to cerebrovascular endothelial cells via an intrinsic mitochondrial mechanism

Propofol Ameliorates ox-LDL-Induced Endothelial Damage Through Enhancing Autophagy via PI3K/Akt/m-TOR Pathway: A Novel Therapeutic Strategy in Atherosclerosis

Objective: Atherosclerosis (AS) represents a common age-associated disease, which may be accelerated by oxidized low-density lipoprotein (ox-LDL)-induced endothelial cell injury. This study aimed to investigate the effects of Propofol on ox-LDL-induced endothelial damage and the underlying molecular mechanisms.

Methods: Human umbilical vein endothelial cells (HUVECs) were exposed to ox-LDL to induce endothelial damage. HUVECs were pretreated with 0, 5, 25 and 100°μM Propofol, followed by exposure to 100°μg/ml ox-LDL for 24°h. Cell viability was assessed by cell counting kit-8 (CCK-8) assay. The expression of autophagy- and apoptosis-related proteins was detected via western blot. Autophagosome was investigated under a transmission electron microscope. After co-treatment with autophagy inhibitor Bafilomycin A1 or si-Beclin-1, cell apoptosis was detected by flow cytometry. Furthermore, under cotreatment with PI3K activator 740Y-P, PI3K/Akt/m-TOR pathway- and autophagy-related proteins were examined by western blot.

Results: With a concentration-dependent manner, Propofol promoted the viability of HUVECs exposed to ox-LDL, and increased LC3-II/I ratio and Beclin-1 expression, and decreased P62 expression. The formation of autophagosome was enhanced by Propofol. Furthermore, Propofol treatment elevated Bcl-2/Bax ratio and lowered Caspase-3 expression. Bafilomycin A1 or si-Beclin-1 distinctly ameliorated the inhibitory effects of Propofol on apoptosis in ox-LDL-exposed HUVECs. Moreover, Propofol lowered the activation of PI3K/Akt/m-TOR pathway in HUVECs under exposure to ox-LDL. However, its inhibitory effects were weakened by 740Y-P.

Conclusion: Collectively, this study revealed that Propofol could ameliorate ox-LDL-induced endothelial damage through enhancing autophagy via PI3K/Akt/m-TOR pathway, which might offer a novel therapeutic strategy in AS.

Honokiol Induces Autophagic Apoptosis in Neuroblastoma Cells through a P53-Dependent Pathway

In children, neuroblastomas are the most common and deadly solid tumor. Our previous studies showed that honokiol can cross the blood–brain barrier and kill neuroblastoma cells. In this study, we further evaluated if exposure to honokiol for short periods could induce autophagy and subsequent apoptosis of neuroblastoma cells and possible mechanisms. Exposure of neuroblastoma neuro-2a cells to honokiol for 24[Formula: see text]h induced morphological shrinkage and cell death. As to the mechanisms, honokiol consecutively induced cytochrome c release from mitochondria, caspase-3 activation, DNA fragmentation and cell apoptosis. Separately, honokiol time-dependently augmented the proportion of autophagic cells and the ratio of light chain 3 (LC3)-II/LC3-I. Pretreatment of neuro-2a cells with 3-methyladenine, an inhibitor of autophagy, attenuated honokiol-induced cell autophagy, caspase-3 activation, DNA damage and cell apoptosis. In contrast, stimulation of autophagy by rapamycin, an inducer of autophagy, significantly enhanced honokiol-induced cell apoptosis. Furthermore, honokiol-induced autophagic apoptosis was confirmed in neuroblastoma NB41A3 cells. Knocking down translation of p53 using RNA interference attenuated honokiol-induced autophagy and apoptosis in neuro-2a and NB41A3 cells. Taken together, this study showed that at early periods, honokiol can induce autophagic apoptosis of neuroblastoma cells through activating a p53-dependent mechanism. Consequently, honokiol has the potential to be a therapeutic option for neuroblastomas.

Sepsis-induced liver dysfunction was ameliorated by propofol via suppressing hepatic lipid peroxidation, inflammation, and drug interactions

AIMS

Our previous study showed that propofol can protect against sepsis-induced insults through suppressing liver nitrosation and inflammation. This study further evaluated the mechanisms of propofol-caused protection from sepsis-induced liver dysfunction.

MAIN METHODS

Male Wistar rats were subjected to cecal ligation and puncture (CLP) and then exposed to propofol. Levels of hepatic oxidative stress and lipid peroxidation were consecutively measured. Expressions of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-4 messenger (m)RNA or proteins were quantified. Effects of propofol on microsomal pentoxyresorufin O-dealkelase (PROD) and ethoxycoumarin O-deethylase (ECOD) activities were determined.

KEY FINDINGS

Administration of propofol to CLP-treated rats significantly attenuated sepsis-induced insults. CLP caused augmented serum aspartate aminotransferase and alanine aminotransferase activities and concurrently triggered liver damage. In contrast, treatment with propofol protected against CLP-induced liver dysfunction. As to the mechanisms, the CLP-induced increases in oxidative stress and lipid peroxidation levels and TNF-α and IL-1β mRNA and protein expressions were subsequently attenuated by propofol. Furthermore, administration of CLP-treated rats with propofol augmented levels of IL-4 in the liver. Phenobarbital treatment of liver microsomes in CLP-treated rats produced less amplification of PROD and ECOD activities, and a smaller amount of 4-hydroxypropofol was metabolized from propofol by liver microsomes. In contrast, more drug interactions occurred with propofol, which decreased PROD and ECOD activities in liver microsomes of CLP-treated rats.

SIGNIFICANCE

Taken together, the present study showed that propofol can protect against sepsis-induced liver dysfunction through suppressing hepatic oxidative stress, lipid peroxidation, inflammation, and drug biotransformation and interactions in the liver.

Honokiol enhances temozolomide-induced apoptotic insults to malignant glioma cells via an intrinsic mitochondrion-dependent pathway

BACKGROUND

Temozolomide (TMZ) is a first-line chemotherapeutic drug for malignant gliomas. Nonetheless, TMZ-induced side effects and drug resistance remain challenges. Our previous study showed the suppressive effects of honokiol on growth of gliomas.

PURPOSE

This study was further aimed to evaluate if honokiol could enhance TMZ-induced insults toward malignant glioma cells and its possible mechanisms.

METHODS

Human U87 MG glioma cells were exposed to TMZ, honokiol, and a combination of TMZ and honokiol. Cell survival, apoptosis, necrosis, and proliferation were successively assayed. Fluorometric substrate assays were conducted to determine activities of caspase-3, -6, -8, and -9. Levels of Fas ligand, Bax, and cytochrome c were immunodetected. Translocation of Bax to mitochondria were examined using confocal microscopy. Mitochondrial function was evaluated by assaying the mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and complex I enzyme activity. Caspase-6 activity was suppressed using specific peptide inhibitors. The honokiol-induced effects were further confirmed using human U373 MG and murine GL261 cells.

RESULTS

Exposure of human U87 MG glioma cells to honokiol significantly increased TMZ-induced DNA fragmentation and cell apoptosis. Interestingly, honokiol enhanced intrinsic caspase-9 activity without affecting extrinsic Fas ligand levels and caspase-8 activity. Sequentially, TMZ-induced changes in Bax translocation, the MMP, mitochondrial complex I enzyme activity, intracellular ROS levels, and cytochrome c release were enhanced by honokiol. Consequently, honokiol amplified TMZ-induced activation of caspases-3 and -6 in human U87 MG cells. Fascinatingly, suppressing caspase-6 activity concurrently decreased honokiol-induced DNA fragmentation and cell apoptosis. The honokiol-involved improvement in TMZ-induced intrinsic apoptosis was also confirmed in human U373 MG and murine GL261 glioma cells.

CONCLUSIONS

This study showed that honokiol can enhance TMZ-induced apoptotic insults to glioma cells via an intrinsic mitochondrion-dependent mechanism. Our results suggest the therapeutic potential of honokiol to attenuate TMZ-induced side effects.

The Effect of Propofol on Mitochondrial Fission during Oxygen-Glucose Deprivation and Reperfusion Injury in Rat Hippocampal Neurons

The neuroprotective role of propofol in transient global and focal cerebral ischemia reperfusion (I/R) animal model has recently been highlighted. However, no studies have conducted to explore the relationship between mitochondrial fission/fusion and I/R injury under the intervention of propofol. Moreover, neuroprotective mechanism of propofol is yet unclear. Culturing primary hippocampal cells were subjected to oxygen-glucose deprivation and re-oxygenation (OGD/R) model, as a model of cerebral I/R in vitro. Methods CCK-8 assay was used to test the effect of propofol on cell viability. We examined the effect of propofol on mitochondrial ultrastructure and mitochondrial fission evoked by OGD/R with transmission electron microscopy and immunofluorescence assay. To investigate possible neuroprotective mechanisms, the authors then examined whether propofol could inhibit calcium-overload, calcineurin (CaN) activation and the phosphorylation of dynamin-related protein 1 (Drp1) during the period of OGD/R, as well as the combination of Drp1-ser 637 and fission 1 (Fis1) protein by immunofluorescence assay, ELISA and double-labeling immunofluorescence analysis. Finally, the expression of Drp1-ser 637 and Fis1, apoptosis inducing factor (AIF) and cytochrome C (Cyt C) were detected by western blot. When added in culture media during OGD period, propofol (0.1μM-50μM) could alleviate neurons injury and protect mitochondrial ultrastructure, meanwhile inhibit mitochondrial fission. Furthermore, the concentration of intracellular free Ca2+, CaN activition and the phosphorylation of Drp1-ser637 were suppressed, as well as the translocation and combination of Drp1-ser 637 and Fis1. The authors also found that the expression of Cyt C, AIF, Drp1-ser637 and Fis1 were down-regulated. Notably, high dose of propofol (100μM-200μM) were confirmed to decrease the survival of neurons based on results of cell viability. Propofol could inhibit mitochondrial fission and mitochondrial apoptotic pathway evoked by OGD/R in rat hippocampal neurons, which may be via depressing calcium-overload.

Preclinical effects of honokiol on treating glioblastoma multiforme via G1 phase arrest and cell apoptosis

BACKGROUND

Our previous study showed that honokiol, a bioactive polyphenol, can traverse the blood-brain barrier and kills neuroblastoma cells.

PURPOSE

In this study, we further evaluated the preclinical effects of honokiol on development of malignant glioma and the possible mechanisms.

METHODS

Effects of honokiol on viability, caspase activities, apoptosis, and cell cycle arrest in human glioma U87 MG or U373MG cells were assayed. As to the mechanisms, levels of inactive or phosphorylated (p) p53, p21, CDK6, CDK4, cyclin D1, and E2F1 were immunodetected. Pifithrin-α (PFN-α), a p53 inhibitor, was pretreated into the cells. Finally, our in vitro findings were confirmed using intracranial nude mice implanted with U87 MG cells.

RESULTS

Exposure of human U87 MG glioma cells to honokiol decreased the cell viability. In parallel, honokiol induced activations of caspase-8, -9, and -3, apoptosis, and G1 cell cycle arrest. Treatment of U87 MG cells with honokiol increased p53 phosphorylation and p21 levels. Honokiol provoked signal-transducing downregulation of CDK6, CDK4, cyclin D1, phosphorylated (p)RB, and E2F1. Pretreatment of U87 MG cells with PFN-α significantly reversed honokiol-induced p53 phosphorylation and p21 augmentation. Honokiol-induced alterations in levels of CDK6, CDK4, cyclin D1, p-RB, and E2F1 were attenuated by PFN-α. Furthermore, honokiol could induce apoptotic insults to human U373MG glioma cells. In our in vivo model, administration of honokiol prolonged the survival rate of nude mice implanted with U87 MG cells and induced caspase-3 activation and chronological changes in p53, p21, CDK6, CDK4, cyclin D1, p-RB, and E2F1.

CONCLUSIONS

Honokiol can repress human glioma growth by inducing apoptosis and cell cycle arrest in tumor cells though activating a p53/cyclin D1/CDK6/CDK4/E2F1-dependent pathway. Our results suggest the potential of honokiol in therapies for human malignant gliomas.

Neuron-derived orphan receptor 1 transduces survival signals in neuronal cells in response to hypoxia-induced apoptotic insults

OBJECT Hypoxia can induce cell death or trigger adaptive mechanisms to guarantee cell survival. Neuron-derived orphan receptor 1 (NOR-1) works as an early-response protein in response to a variety of environmental stresses. In this study, the authors evaluated the roles of NOR-1 in hypoxia-induced neuronal insults. METHODS Neuro-2a cells were exposed to oxygen/glucose deprivation (OGD). Cell viability, cell morphology, cas-pase-3 activity, DNA fragmentation, and cell apoptosis were assayed to determine the mechanisms of OGD-induced neuronal insults. RNA and protein analyses were carried out to evaluate the effects of OGD on expressions of NOR-1, cAMP response element-binding (CREB), and cellular inhibitor of apoptosis protein 2 (cIAP2) genes. Translations of these gene expressions were knocked down using RNA interference. Mice subjected to traumatic brain injury (TBI) and NOR-1 was immunodetected. RESULTS Exposure of neuro-2a cells to OGD decreased cell viability in a time-dependent manner. Additionally, OGD led to cell shrinkage, DNA fragmentation, and cell apoptosis. In parallel, treatment of neuro-2a cells with OGD time dependently increased cellular NOR-1 mRNA and protein expressions. Interestingly, administration of TBI also augmented NOR-1 levels in the impacted regions of mice. As to the mechanism, exposure to OGD increased nuclear levels of the transcription factor CREB protein. Downregulating CREB expression using RNA interference simultaneously inhibited OGD-induced NOR-1 mRNA expression. Also, levels of cIAP2 mRNA and protein in neuro-2a cells were augmented by OGD. After reducing cIAP2 translation, OGD-induced cell death was reduced. Sequentially, application of NOR-1 small interfering RNA to neuro-2a cells significantly inhibited OGD-induced cIAP2 mRNA expression and concurrently alleviated hypoxia-induced alterations in cell viability, caspase-3 activation, DNA damage, and cell apoptosis. CONCLUSIONS This study shows that NOR-1 can transduce survival signals in neuronal cells responsible for hypoxiainduced apoptotic insults through activation of a CREB/cIAP2-dependent mechanism.

Propofol attenuates hydrogenperoxide-induced apoptosis in human umbilical vein endothelial cells via multiple signaling pathways

BACKGROUND

Propofol has been reported to protect vascular endothelial cells against oxidative stress. In this study we investigated its effect on hydrogen peroxide (H2O2)-induced apoptosis of human umbilical vein endothelial cells (HUVECs) and examined the possible signaling pathways.

METHODS

HUVECs were pretreated with propofol (1, 5, 25, and 50 µM) for 30 min and then co-incubated with 0.4 mM H2O2 for 4 h. Cell viability was assessed using a Cell Counting Kit-8. Cell apoptosis was analyzed using flow cytometry with annexin V/propidium iodide staining, and evaluated by quantifying caspase-3, Bax, and Bcl-2 expression levels. The expression levels of p38 mitogen activated protein kinase (MAPK), phosphorylated (p)-p38 MAPK, cJun-N-terminal kinases (JNK), phosphorylated (p)-JNK, Akt and phosphorylated Akt [(p)-Akt] (Ser473) were measured by western blotting.

RESULTS

H2O2 treatment induced the activation of caspase-3, downregulated Bcl-2 expression, and up-regulated Bax expression, all of which were dose-dependently attenuated by propofol pretreatment. Furthermore, propofol significantly ameliorated H2O2-induced phosphorylation of p38 MAPK, JNK, and Akt in HUVECs.

CONCLUSIONS

Propofol can protect HUVECs against H2O2-induced apoptosis via a mechanism that may involve p38 MAPK, JNK, and Akt signaling pathways.

Propofol ameliorates calpain-induced collapsin response mediator protein-2 proteolysis in traumatic brain injury in rats

BACKGROUND

Collapsin response mediator protein-2 (CRMP2), a multifunctional cytosolic protein highly expressed in the brain, is degraded by calpain following traumatic brain injury (TBI), possibly inhibiting posttraumatic neurite regeneration. Lipid peroxidation (LP) is involved in triggering postinjury CRMP2 proteolysis. We examined the hypothesis that propofol could attenuate LP, calpain-induced CRMP2 degradation, and brain injury after TBI.

METHODS

A unilateral moderate controlled cortical impact injury was induced in adult male Sprague-Dawley rats. The animals were randomly divided into seven groups: Sham control group, TBI group, TBI + propofol groups (including propofol 1 h, 2 h, and 4 h groups), TBI + U83836E group and TBI + fat emulsion group. The LP inhibitor U83836E was used as a control to identify that antioxidation partially accounts for the potential neuroprotective effects of propofol. The solvent of propofol, fat emulsion, was used as the vehicle control. Ipsilateral cortex tissues were harvested at 24 h post-TBI. Immunofluorescent staining, Western blot analysis, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling were used to evaluate LP, calpain activity, CRMP2 proteolysis and programmed cell death. The data were statistically analyzed using one-way analysis of variance and a paired t-test.

RESULTS

Propofol and U83836E significantly ameliorated the CRMP2 proteolysis. In addition, both propofol and U83836E significantly decreased the ratio of 145-kDa αII-spectrin breakdown products to intact 270-kDa spectrin, the 4-hydroxynonenal expression and programmed cell death in the pericontusional cortex at 24 h after TBI. There was no difference between the TBI group and the fat emulsion group.

CONCLUSIONS

These results demonstrate that propofol postconditioning alleviates calpain-mediated CRMP2 proteolysis and provides neuroprotective effects following moderate TBI potentially by counteracting LP and reducing calpain activation.

Propofol protects against high glucose-induced endothelial apoptosis and dysfunction in human umbilical vein endothelial cells

BACKGROUND

Perioperative hyperglycemia is a common clinical metabolic disorder. Hyperglycemia could induce endothelial apoptosis and dysfunction. Propofol is a widely used IV anesthetic drug in clinical settings. In the present study, we examined whether and how propofol reduced high glucose-induced endothelial apoptosis and dysfunction in human umbilical vein endothelial cells (HUVECs).

METHODS

HUVECs were cultured with different concentrations (5, 10, 15, and 25 mM) of glucose for different times (4, 8, 12, and 24 hours). To study the effect of propofol, cells were incubated with different concentrations (0.2, 1, 5, and 25 μM) of propofol for 2 hours. In parallel experiments, cells were incubated in 5 mM glucose as control. Nitric oxide (NO) production was measured with a nitrate reductase assay. Cell viability was determined with a Cell Counting Kit-8. Protein expression of active caspase 3, cytochrome c, endothelial NO synthase (eNOS), p-eNOS-Thr, p66, protein kinase C βII (PKCβII), and p-PKCβII-Ser was measured by Western blot analysis. Accumulation of superoxide anion (O2˙) was measured with the reduction of ferricytochrome c. Cell apoptosis was determined with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining.

RESULTS

Compared with control, high glucose decreased NO production (P < 0.0001) and reduced cells viability (P < 0.0001) in HUVECs. Compared with high glucose treatment, pretreatment of cells with propofol (5 μM, 2 hours) reduced high glucose-induced inhibitory p-eNOS-Thr phosphorylation (P < 0.0001), increasing NO production (P = 0.0007), decreased high glucose-induced p66 expression (P < 0.0001) and p66 mitochondrial translocation (P < 0.0001), O2˙ accumulation (P < 0.0001), mitochondrial cytochrome c release (P < 0.0001), active caspase 3 expression (P < 0.0001), and enhancing endothelial viability (P < 0.0001). Furthermore, propofol inhibited high glucose-induced PKCβII expression (P = 0.0002) and p-PKCβII-Ser phosphorylation (P < 0.0001). Moreover, the observed protective effect of propofol was quite similar to that of PKCβII inhibitor.

CONCLUSIONS

Propofol, by a mechanism of decreasing high glucose-induced PKCβII expression and p-PKCβII-Ser phosphorylation, inhibits high glucose-induced p66 mitochondrial translocation, therefore protecting HUVECs from high glucose-induced endothelial dysfunction and apoptosis.

A possible molecular mechanism of hearing loss during cerebral ischemia in mice

Ischemic brain stroke is a leading cause of disability and includes hearing loss. Clinical reports have also suggested that there is hearing loss in stroke patients but the mechanism was not determined. Therefore, we hypothesized that hearing loss after cerebral ischemia may be associated with changes to the synapse, gap junction, and sodium channel (NaC) proteins. Ischemia-reperfusion injury was induced in wild-type mice (I/R group). The lesion volume was determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining of the brain sections. BBB disruption was confirmed by Evans blue staining and leakage of bovine serum albumin labeled with fluorescein isothiocyanate (BSA-FITC). We found that brain edema, infarct size, and permeability were increased in ischemic mice as compared with the sham-operated group. Caspase-3, caspase-9, and TUNEL-positive cells were increased in I/R mice, indicating neuronal apoptosis. Moreover, there were increased expressions of matrix metalloprotease's (MMP-2, -3, -9, and -13), interleukin (IL)-6, and decreased expressions of tight junction proteins (TJP) in the I/R group, as compared with the sham group, which signifies inflammation and BBB disruption. We also observed decreased levels of post-synaptic density protein-95 (PSD-95), synapse-associated protein 97 (SAP-97), connexin-43, NaC-α, and NaC-β, and increased expression of connexin-45, whereas no substantial change was observed in connexin-26 expression in the I/R group. Interestingly, auditory response was reduced in the I/R mice, indicating hearing loss. These data suggest that hearing loss in ischemic mice was primarily due to alterations in connexin, synapses, and NaC channels.

Ring-oxidative biotransformation and drug interactions of propofol in the livers of rats

Propofol, an intravenous anesthetic agent, is widely used for inducing and maintaining anesthesia during surgical procedures and for sedating intensive care unit patients. In the clinic, rapid elimination is one of the major advantages of propofol. Meanwhile, the biotransformation and drug interactions of propofol in rat livers are still little known. In this study, we evaluated the ring-oxidative metabolism of propofol in phenobarbital-treated rat livers and possible drug interactions. Administration of phenobarbital to male Wistar rats significantly increased levels of hepatic cytochrome P450 (CYP) 2B1/2 and microsomal pentoxyresorufin O-dealkylase (PROD) activity. Analyses by high-performance liquid chromatography and liquid chromatography mass spectroscopy revealed that propofol was metabolized by phenobarbital-treated rat liver microsomes into 4-hydroxypropofol. In comparison, PROD activity and 4-hydroxy-propofol production from propofol metabolism were suppressed by orphenodrine, an inhibitor of CYP2B1/2, and a polyclonal antibody against rat CYP2B1/2 protein. Furthermore, exposure of rats to propofol did not affect the basal or phenobarbital-enhanced levels of hepatic CYP2B1/2 protein. Meanwhile, propofol decreased the dealkylation of pentoxyresorufin by phenobarbital-treated rat liver microsomes in a concentration-dependent manner. Taken together, this study shows that rat hepatic CYP2B1/2 plays a critical role in the ring-oxidative metabolism of propofol into 4-hydroxypropofol, and this anesthetic agent can inhibit CYP2B1/2 activity without affecting protein synthesis.

Propofol prevents neuronal mtDNA deletion and cerebral damage due to ischemia/reperfusion injury in rats

Propofol is a commonly used intravenous anesthetic that has been demonstrated to be neuroprotective against cerebral ischemia-reperfusion (I/R) injury. It remains unclear whether this protective effect has any relationship with the prevention of neuronal mitochondrial deoxyribonucleic acid (mtDNA) deletion. In this study, 81 Wistar rats were randomly divided into three groups (n = 27 each): sham (S group), ischemia/reperfusion (I/R group), or propofol (P group). Cerebral ischemia was induced by clamping the bilateral common carotid arteries for 10 min. A polymerase chain reaction (PCR) was conducted to determine mtDNA deletion. The mitochondrial membrane potential (MMP) changes were detected via microplate reader. The neuronal ultrastructure was visualized via electron microscope. MMP significantly decreased after I/R (P<0.05 compared with the S group). Severe damage to the ultrastructure of neuronal mitochondria was observed in cerebral I/R injury. When propofol (1.0mg/kg/min) was administered intravenously for 1h prior to the induction of I/R, the neuronal structure and MMP were well preserved, and mtDNA deletion was reduced after ischemia/reperfusion injury compared with the I/R group (P<0.05). These data suggested that propofol prevented mtDNA deletion and preserved a normal structure and MMP, which are important for normal mitochondrial function and increase neuronal resistance to I/R injury.

Improving effects of chitosan nanofiber scaffolds on osteoblast proliferation and maturation

Osteoblast maturation plays a key role in regulating osteogenesis. Electrospun nanofibrous products were reported to possess a high surface area and porosity. In this study, we developed chitosan nanofibers and examined the effects of nanofibrous scaffolds on osteoblast maturation and the possible mechanisms. Macro- and micro observations of the chitosan nanofibers revealed that these nanoproducts had a flat surface and well-distributed fibers with nanoscale diameters. Mouse osteoblasts were able to attach onto the chitosan nanofiber scaffolds, and the scaffolds degraded in a time-dependent manner. Analysis by scanning electron microscopy further showed mouse osteoblasts adhered onto the scaffolds along the nanofibers, and cell-cell communication was also detected. Mouse osteoblasts grew much better on chitosan nanofiber scaffolds than on chitosan films. In addition, human osteoblasts were able to adhere and grow on the chitosan nanofiber scaffolds. Interestingly, culturing human osteoblasts on chitosan nanofiber scaffolds time-dependently increased DNA replication and cell proliferation. In parallel, administration of human osteoblasts onto chitosan nanofibers significantly induced osteopontin, osteocalcin, and alkaline phosphatase (ALP) messenger (m)RNA expression. As to the mechanism, chitosan nanofibers triggered runt-related transcription factor 2 mRNA and protein syntheses. Consequently, results of ALP-, alizarin red-, and von Kossa-staining analyses showed that chitosan nanofibers improved osteoblast mineralization. Taken together, results of this study demonstrate that chitosan nanofibers can stimulate osteoblast proliferation and maturation via runt-related transcription factor 2-mediated regulation of osteoblast-associated osteopontin, osteocalcin, and ALP gene expression.

Safety and efficacy of propofol administered by paediatricians during procedural sedation in children

AIM

The aim of this study was to determine the safety and the efficacy of paediatrician-administered propofol in children undergoing different painful procedures.

METHODS

We conducted a retrospective study over a 12-year period in three Italian hospitals. A specific training protocol was developed in each institution to train paediatricians administering propofol for painful procedures.

RESULTS

In this study, 36,516 procedural sedations were performed. Deep sedation was achieved in all patients. None of the children experienced severe side effects or prolonged hospitalisation. There were six calls to the emergency team (0.02%): three for prolonged laryngospasm, one for bleeding, one for intestinal perforation and one during lumbar puncture. Nineteen patients (0.05%) developed hypotension requiring saline solution administration, 128 children (0.4%) needed O2 ventilation by face mask, mainly during upper endoscopy, 78 (0.2%) patients experienced laryngospasm, and 15 (0.04%) had bronchospasm. There were no differences in the incidence of major complications among the three hospitals, while minor complications were higher in children undergoing gastroscopy.

CONCLUSION

This multicentre study demonstrates the safety and the efficacy of paediatrician-administered propofol for procedural sedation in children and highlights the importance of appropriate training for paediatricians to increase the safety of this procedure in children.

Involvement of the blood-brain barrier opening in cognitive decline in aged rats following orthopedic surgery and high concentration of sevoflurane inhalation

The underlying causes of postoperative cognitive decline (POCD) in old patients remained unelucidated, and there are little descriptions on mechanisms associated with the blood-brain barrier (BBB) disruption during POCD. We therefore tested the effects of orthopedic surgery with different concentrations of sevoflurane for 2 h on the behavior test and the BBB permeability in aged rats. 18-month rats were divided into control group and surgical group with propofol anesthesia (0.7 mgkg(-1) min(-1)) and 1.0 MAC, 1.3 MAC, and 1.5 MAC sevoflurane inhalation for 2 h. We assessed their cognitive function via Y-maze and fear conditioning test on day 1, 3, and 7 after experiments. Animals were then assigned to control group, propofol (2 h, 0.7 mgkg(-1) min(-1)) group, surgery plus propofol group and surgery plus 1.5 MAC sevoflurane inhalation for 2h. Their hippocampal BBB permeability was detected with Evans blue quantification. Alterations of tight junctions in hippocampus were measured with occludin and claudin-5 western blot. Then we assessed matrix metalloproteinase-2,9 (MMP-2,9) via western blot and immunohistochemistry staining at day 1, 3, 7, and 14 after experiments. Surgery impaired cognitive function and increased Evans blue leakage into the hippocampus in aged rats while 2 h of 1.5 MAC sevoflurane inhalation potentiated these effects. Surgery induced occludin protein expression decreases and MMP-2,9 proteins increase and these influences can be enhanced by high concentration of sevoflurane inhalation. In conclusion, 1.5 MAC sevoflurane for 2 h exacerbated cognitive impairment induced by orthopedic surgery in aged rats and the breach in BBB may be involved in this process.