Ryanodine receptor inhibitor dantrolene reduces hypoxic-ischemic brain injury in neonatal mice.

Ryanodine receptors (RyR) located on the membrane of the endoplasmic reticulum (ER), are a potent regulator of intracellular calcium levels upon activation. Dysregulated Ca2+ homeostasis is characteristic of hypoxic-ischemic (HI) brain injury and ultimately leads to neurodegeneration. RyRs have thereby been implicated in the Ca2+ imbalance that occurs during and after HI. In this study, we investigated the effects of RyR antagonist, dantrolene, on HI brain injury in neonatal mice. We found that administration of dantrolene (i.p.) on postnatal day 7 mice reduced the infarction volume and morphological damage induced by HI, and improved functional recovery as assessed by neurobehavioral testing. The neuroprotective effect of dantrolene was further demonstrated in neuronal cell culture in vitro, where dantrolene significantly reduced oxygen-glucose deprivation (OGD)-induced cell death. Fura-2 calcium imaging confirmed that dantrolene reduced the intracellular calcium level in cultured cortical neurons in vitro. Finally, Western blot analysis showed that dantrolene treatment reduced cleaved caspase-3 and -9 apoptotic proteins, and elevated pro-survival protein kinase C (PKC) protein levels. Taken together, our results demonstrate that dantrolene exerts neuroprotective effects against neonatal HI brain injury. This suggests that RyRs play a role in mediating the ionic imbalance induced by HI and therefore represent a potential target for drug development.

Canadian consensus statement: enhanced recovery after surgery in bariatric surgery.

BACKGROUND: In Canada, bariatric surgery continues to remain the most effective treatment for severe obesity and its comorbidities. As the number of bariatric surgeries continues to grow, the need for consensus guidelines for optimal perioperative care is imperative. In colorectal surgery, enhanced recovery after surgery (ERAS) protocols were created for this purpose. The objective of this review is to develop evidence-based ERAS guidelines for bariatric surgery. METHODS: A literature search of the MEDLINE database was performed using ERAS-specific search terms. Recently published articles with a focus on randomized controlled trials, systematic reviews, and meta-analyses were included. Quality of evidence and recommendations were evaluated using the GRADE assessment system. RESULTS: Canadian bariatric surgeons from six provinces and ten bariatric centers performed a review of the evidence surrounding ERAS in bariatric surgery and created consensus guidelines for 14 essential ERAS elements. Our main recommendations were (1) to encourage participation in a presurgical weight loss program; (2) to abstain from tobacco and excessive alcohol; (3) low-calorie liquid diet for at least 2 weeks prior to surgery; (4) to avoid preanesthetic anxiolytics and long-acting opioids; (5) unfractionated or low-molecular-weight heparin prior to surgery; (6) antibiotic prophylaxis with cefazolin ± metronidazole; (7) reduced opioids during surgery; (8) surgeon preference regarding intraoperative leak testing; (9) nasogastric intubation needed only for Veress access; (10) to avoid abdominal drains and urinary catheters; (11) to prevent ileus by discontinuing intravenous fluids early; (12) postoperative analgesia with acetaminophen, short-term NSAIDS, and minimal opioids; (13) to resume full fluid diet on first postoperative day; (14) early telephone follow-up with full clinic follow-up at 3-4 weeks. CONCLUSIONS: The purpose of addressing these ERAS elements is to develop guidelines that can be implemented and practiced clinically. ERAS is an excellent model that improves surgical efficiency and acts as a common perioperative pathway. In the interim, this multimodal bariatric perioperative guideline serves as a common consensus point for Canadian bariatric surgeons.

TRPM2-AS inhibits the growth, migration, and invasion of gliomas through JNK, c-Jun, and RGS4.

Gliomas are a group of brain cancers with high mortality and morbidity. Understanding the molecular mechanisms is important for the prevention or treatment of gliomas. The present study was to investigate the effects and mechanisms of long noncoding RNA TRPM2-AS in gliomas proliferation, migration, and invasion. We first compared the levels of TRPM2-AS in 111 patients with glioma to that of the normal control group by a quantitative polymerase chain reaction. The results indicated a significant increase of TRPM2-AS in patients with glioma (2.43 folds of control, p = .0135). MTT methods, wound healing assays, transwell analysis, and clone formation analysis indicated the overexpression of TRPM2-AS promoted the proliferation, migration, and invasion of U251 and U87 cells, while downregulation of TRPM2-AS inhibited the cell proliferation, migration, and invasion significantly (p < .05). To further uncover the mechanisms, bioinformatics analysis was conducted on the expression profiles, GSE40687 and GSE4290, from the Gene Expression Omnibus database. One hundred fifty-six genes were differentially expressed in both datasets (FC > 2.0; p = .05). Among these differentially expressed genes, the level of RGS4 messenger RNA was drastically regulated by TRPM2-AS. Further western-blot analysis indicated the increase of RGS4 protein expression and decrease of p-JNK/JNK and p-c-Jun/c-Jun ratio after TRPM2-AS overexpression. On the other hand, inhibition of TRPM2-AS by small interfering RNA suppressed the expression of RGS4 and promoted the ratios of p-JNK/JNK and p-c-Jun/c-Jun. The present work indicated the mechanisms of the participation of TRPM2-AS in the progression of gliomas might, at least partly, be related to JNK, c-Jun, and RGS4. Our work provided new insights into the underlying mechanisms of glioma cellular functions.

The LIM homeodomain protein ISL1 mediates the function of TCF7L2 in pancreatic beta cells.

Pancreatic ß-cell Tcf7l2 deletion or its functional knockdown suggested the essential role of this Wnt pathway effector in controlling insulin secretion, glucose homeostasis and ß-cell gene expression. As the LIM homeodomain protein ISL1 is a suggested Wnt pathway downstream target, we hypothesize that it mediates metabolic functions of TCF7L2. We aimed to determine the role of ISL1 in mediating the function of TCF7L2 and the incretin hormone GLP-1 in pancreatic ß-cells. The effect of dominant negative TCF7L2 (TCF7L2DN) mediated Wnt pathway functional knockdown on Isl1 expression was determined in ßTCFDN mouse islets and in the rat insulinoma cell line INS-1 832/13. Luciferase reporter assay and chromatin immunoprecipitation were utilized to determine whether Isl1 is a direct downstream target of Tcf7l2 TCF7L2DN adenovirus infection and siRNA-mediated Isl1 knockdown on ß-cell gene expression were compared. Furthermore, Isl1 knockdown on GLP-1 stimulated ß-catenin S675 phosphorylation and insulin secretion was determined. We found that TCF7L2DN repressed ISL1 levels in ßTCFDN islets and the INS-1 832/13 cell line. Wnt stimulators enhanced Isl1 promoter activity and binding of TCF7L2 on Isl1 promoter. TCF7L2DN adenovirus infection and Isl1 knockdown generated similar repression on expression of ß-cell genes, including the ones that encode GLUT2 and GLP-1 receptor. Either TCF7L2DN adenovirus infection or Isl1 knockdown attenuated GLP-1-stimulated ß-catenin S675 phosphorylation in INS-1 832/13 cells or mouse islets and GLP-1 stimulated insulin secretion in INS-1 832/13 or MIN6 cells. Our observations support the existence of TCF7L2-ISL1 transcriptional network, and we suggest that this network also mediates ß-cell function of GLP-1.

Pharmacological approaches promoting stem cell-based therapy following ischemic stroke insults.

Stroke can lead to long-term neurological deficits. Adult neurogenesis, the continuous generation of newborn neurons in distinct regions of the brain throughout life, has been considered as one of the appoaches to restore the neurological function following ischemic stroke. However, ischemia-induced spontaneous neurogenesis is not suffcient, thus cell-based therapy, including infusing exogenous stem cells or stimulating endogenous stem cells to help repair of injured brain, has been studied in numerous animal experiments and some pilot clinical trials. While the effects of cell-based therapy on neurological function during recovery remains unproven in randomized controlled trials, pharmacological agents have been administrated to assist the cell-based therapy. In this review, we summarized the limitations of ischemia-induced neurogenesis and stem-cell transplantation, as well as the potential proneuroregenerative effects of drugs that may enhance efficacy of cell-based therapies. Specifically, we discussed drugs that enhance proliferation, migration, differentiation, survival and function connectivity of newborn neurons, which may restore neurobehavioral function and improve outcomes in stroke patients.

The role of KATP channels in cerebral ischemic stroke and diabetes.

ATP-sensitive potassium (KATP) channels are ubiquitously expressed on the plasma membrane of cells in multiple organs, including the heart, pancreas and brain. KATP channels play important roles in controlling and regulating cellular functions in response to metabolic state, which are inhibited by ATP and activated by Mg-ADP, allowing the cell to couple cellular metabolic state (ATP/ADP ratio) to electrical activity of the cell membrane. KATP channels mediate insulin secretion in pancreatic islet beta cells, and controlling vascular tone. Under pathophysiological conditions, KATP channels play cytoprotective role in cardiac myocytes and neurons during ischemia and/or hypoxia. KATP channel is a hetero-octameric complex, consisting of four pore-forming Kir6.x and four regulatory sulfonylurea receptor SURx subunits. These subunits are differentially expressed in various cell types, thus determining the sensitivity of the cells to specific channel modifiers. Sulfonylurea class of antidiabetic drugs blocks KATP channels, which are neuroprotective in stroke, can be one of the high stoke risk factors for diabetic patients. In this review, we discussed the potential effects of KATP channel blockers when used under pathological conditions related to diabetics and cerebral ischemic stroke.

Long non-coding RNAs in ischemic stroke.

Stroke is one of the leading causes of mortality and disability worldwide. Uncovering the cellular and molecular pathophysiological processes in stroke have been a top priority. Long non-coding (lnc) RNAs play critical roles in different kinds of diseases. In recent years, a bulk of aberrantly expressed lncRNAs have been screened out in ischemic stroke patients or ischemia insulted animals using new technologies such as RNA-seq, deep sequencing, and microarrays. Nine specific lncRNAs, antisense non-coding RNA in the INK4 locus (ANRIL), metastasis-associate lung adenocarcinoma transcript 1 (MALAT1), N1LR, maternally expressed gene 3 (MEG3), H19, CaMK2D-associated transcript 1 (C2dat1), Fos downstream transcript (FosDT), small nucleolar RNA host gene 14 (SNHG14), and taurine-upregulated gene 1 (TUG1), were found increased in cerebral ischemic animals and/or oxygen-glucose deprived (OGD) cells. These lncRNAs were suggested to promote cell apoptosis, angiogenesis, inflammation, and cell death. Our Gene Ontology (GO) enrichment analysis predicted that MEG3, H19, and MALAT1 might also be related to functions such as neurogenesis, angiogenesis, and inflammation through mechanisms of gene regulation (DNA transcription, RNA folding, methylation, and gene imprinting). This knowledge may provide a better understanding of the functions and mechanisms of lncRNAs in ischemic stroke. Further elucidating the functions and mechanisms of these lncRNAs in biological systems under normal and pathological conditions may lead to opportunities for identifying biomarkers and novel therapeutic targets of ischemic stroke.

Neuronal Ryanodine Receptors in Development and Aging.

Ryanodine receptors (RyRs) are intracellular calcium-release channels found on the endoplasmic reticulum of all cells. All three RyR isoforms, RyR1-3, are expressed in the brain, with RyR2 predominating. RyRs are localized within the soma, axons, dendritic spines, and presynaptic terminals of neurons. RyRs are highly expressed in the cerebellum, hippocampus, olfactory region, basal ganglia, and cerebral cortex. During the physiological processes of development and aging, the intracellular calcium homeostasis is largely regulated by RyRs. In this review, we discussed the potential mechanisms underlying development- and age-related RyR regulation. Dysregulation of RyRs can cause imbalance of intracellular calcium levels, leading to cellular vulnerability, impairment of synaptic neuronal function, and eventually neuronal death. Regulation of RyRs may play an essential role in cellular senescence associated with aging, and thus may be pharmacological targets for slowing down aberrant processes and neurodegenerative diseases such as Alzheimer's disease.

Transient receptor potential melastatin 2 channels (TRPM2) mediate neonatal hypoxic-ischemic brain injury in mice.

Transient receptor potential melastatin 2 (TRPM2), a calcium-permeable non-selective cation channel, is reported to mediate brain damage following ischemic insults in adult mice. However, the role of TRPM2 channels in neonatal hypoxic-ischemic brain injury remains unknown. We hypothesize that TRPM2+/- and TRPM2-/- neonatal mice have reduced hypoxic-ischemic brain injury. To study the effect of TRPM2 on neonatal brain damage, we used 2,3,5-triphenyltetrazolium chloride (TTC) staining to assess the infarct volume and whole brain imaging to assess morphological changes in the brain. In addition, we also evaluated neurobehavioral outcomes for sensorimotor function 7days following hypoxic-ischemic brain injury. We report that the infarct volumes were significantly smaller and behavioral outcomes were improved in both TRPM2+/- and TRPM2-/- mice compared to that of wildtype mice. Next, we found that TRPM2-null mice showed reduced dephosphorylation of GSK-3ß following hypoxic ischemic injury unlike sham mice. TRPM2+/- and TRPM2-/- mice also had reduced activation of astrocytes and microglia in ipsilateral hemispheres, compared to wildtype mice. These findings suggest that TRPM2 channels play an essential role in mediating hypoxic-ischemic brain injury in neonatal mice. Genetically eliminating TRPM2 channels can provide neuroprotection against hypoxic-ischemic brain injury and this effect is elicited in part through regulation of GSK-3ß.

The Lung is a Host Defense Niche for Immediate Neutrophil-Mediated Vascular Protection.

Bloodstream infection is a hallmark of sepsis, a medically emergent condition requiring rapid treatment. However, upregulation of host defense proteins through toll-like receptors and NFκB requires hours after endotoxin detection. Using confocal pulmonary intravital microscopy, we identified that the lung provides a TLR4-Myd88-and abl tyrosine kinase-dependent niche for immediate CD11b-dependent neutrophil responses to endotoxin and Gram-negative bloodstream pathogens. In an in vivo model of bacteremia, neutrophils crawled to and rapidly phagocytosed Escherichia coli sequestered to the lung endothelium. Therefore, the lung capillaries provide a vascular defensive niche whereby endothelium and neutrophils cooperate for immediate detection and capture of disseminating pathogens.