Roles of Neuronal Protein Kinase Cε on Endoplasmic Reticulum Stress and Autophagic Formation in Diabetic Neuropathy.

In chronic diabetic neuropathy (DN), the cellular mechanisms of neuropathic pain remain unclear. Protein kinase C epsilon (PKCε) is an intracellular signaling molecule that mediates chronic pain. This paper addresses the long-term upregulated PKCε in DN associated with endoplasmic reticulum (ER) stress and autophagic formation and correlates to chronic neuropathic pain. We found that thermal hyperalgesia and mechanical allodynia course development were associated with PKCε upregulation after DN but not skin denervation. Pathologically, PKCε upregulation was associated with the expression of inositol-requiring enzyme 1α (IRE1α; ER stress-related molecule) and ubiquitin D (UBD), which are involved in the ubiquitin-proteasome system (UPS)-mediated degradation of misfolded proteins under ER stress. Manders coefficient analyses revealed an approximately 50% colocalized ratio for IRE1α(+):PKCε(+) neurons (0.34-0.48 for M1 and 0.40-0.58 for M2 Manders coefficients). The colocalized coefficients of UBD/PKCε increased (M1: 0.33 ± 0.03 vs. 0.77 ± 0.04, p < 0.001; M2: 0.29 ± 0.05 vs. 0.78 ± 0.04; p < 0.001) in the acute DN stage. In addition, the regulatory subunit p85 of phosphoinositide 3-kinase, which is involved in regulating insulin signaling, exhibited similar expression patterns to those of IRE1α and UBD; for example, it had highly colocalized ratios to PKCε. The ultrastructural examination further confirmed that autophagic formation was associated with PKCε upregulation. Furthermore, PKCεv1-2, a PKCε specific inhibitor, reverses neuropathic pain, ER stress, and autophagic formation in DN. This finding suggests PKCε plays an upstream molecule in DN-associated neuropathic pain and neuropathology and could provide a potential therapeutic target.

Early detection of the initial stages of LED light-triggered non-alcoholic fatty liver disease by wax physisorption kinetics-Fourier transform infrared imaging.

Light-emitting diodes (LEDs), particularly in the blue waveform range, are regarded as a major source of circadian rhythm dysregulation. A circadian rhythm dysregulation induced by blue LEDs is associated with non-alcoholic fatty liver disease (NAFLD). Hepatocellular accumulation of lipids is a key event in the early stages of NAFLD. Kupffer cells (KCs) have been reported to be lost in the early onset of NAFLD followed by an inflammatory reaction that alters the liver response to lipid overload. This study focused on the detection of the initial stages (subpathological stages) of LED light-triggered NAFLD. Mice were exposed to either blue or white LED irradiation for 44 weeks. Synchrotron radiation-based Fourier-transform infrared microspectroscopy (SR-FTIRM) and wax physisorption kinetic-Fourier transform infrared (WPK-FTIR) imaging were used to evaluate the ratio of lipid to protein and the glycosylation of glycoprotein, respectively. Immunohistopathological studies on KCs and circadian-related proteins were performed. Although liver biopsy showed normal pathology, an SR-FTIRM study revealed a high hepatic lipid-to-protein ratio after receiving LED illumination. The results of WPK-FTIR demonstrated that a high inflammation index was found in the high irradiance of the blue LED illumnation group. These groups showed a decrease in KC number and an increase in Bmal1 and Reverbα circadian protein expression. These findings provide explanations for the reduction of KCs without subsequent inflammation. A significant reduction of Per2 and Cry1 expression is correlated with the findings of WPK-FTIR imaging. WPK-FTIR is a sensitive method for detecting initiative stages of NAFLD induced by long-term blue LED illumination.

SEPT9 Upregulation in Satellite Glial Cells Associated with Diabetic Polyneuropathy in a Type 2 Diabetes-like Rat Model.

Despite the worldwide prevalence and severe complications of type 2 diabetes mellitus (T2DM), the pathophysiological mechanisms underlying the development of diabetic polyneuropathy (DPN) are poorly understood. Beyond strict control of glucose levels, clinical trials for reversing DPN have largely failed. Therefore, understanding the pathophysiological and molecular mechanisms underlying DPN is crucial. Accordingly, this study explored biochemical and neuropathological deficits in a rat model of T2DM induced through high-fat diet (HFD) feeding along with two low-dose streptozotocin (STZ) injections; the deficits were explored through serum lipid, neurobehavioral, neurophysiology, neuropathology, and immunohistochemistry examinations. Our HFD/STZ protocol induced (1) mechanical hyperalgesia and depression-like behaviors, (2) loss of intraepidermal nerve fibers (IENFs) and reduced axonal diameters in sural nerves, and (3) decreased compound muscle action potential. In addition to hyperglycemia, which was correlated with the degree of mechanical hyperalgesia and loss of IENFs, we observed that hypertriglyceridemia was the most dominant deficit in the lipid profiles of the diabetic rats. In particular, SEPT9, the fourth component of the cytoskeleton, increased in the satellite glial cells (SGCs) of the dorsal root ganglia (DRG) in the T2DM-like rats. The number of SEPT9(+) SGCs/DRG was correlated with serum glucose levels and mechanical thresholds. Our findings indicate the putative molecular mechanism underlying DPN, which presumably involves the interaction of SGCs and DRG neurons; nevertheless, further functional research is warranted to clarify the role of SEPT9 in DPN.

Transient receptor potential vanilloid subtype 1 depletion mediates mechanical allodynia through cellular signal alterations in small-fiber neuropathy.

Transient receptor potential vanilloid subtype 1 (TRPV1) is a polymodal nociceptor that monitors noxious thermal sensations. Few studies have addressed the role of TRPV1 in mechanical allodynia in small-fiber neuropathy (SFN) caused by sensory nerve damage. Accordingly, this article reviews the putative mechanisms of TRPV1 depletion that mediates mechanical allodynia in SFN. The intraepidermal nerve fibers (IENFs) degeneration and sensory neuronal injury are the primary characteristics of SFN. Intraepidermal nerve fibers are mainly C-polymodal nociceptors and Aδ-fibers, which mediated allodynic pain after neuronal sensitization. TRPV1 depletion by highly potent neurotoxins induces the upregulation of activating transcription factor 3 and IENFs degeneration which mimics SFN. TRPV1 is predominately expressed by the peptidergic than nonpeptidergic nociceptors, and these neurochemical discrepancies provided the basis of the distinct pathways of thermal analgesia and mechanical allodynia. The depletion of peptidergic nociceptors and their IENFs cause thermal analgesia and sensitized nonpeptidergic nociceptors respond to mechanical allodynia. These distinct pathways of noxious stimuli suggested determined by the neurochemical-dependent neurotrophin cognate receptors such as TrkA and Ret receptors. The neurogenic inflammation after TRPV1 depletion also sensitized Ret receptors which results in mechanical allodynia. The activation of spinal TRPV1(+) neurons may contribute to mechanical allodynia. Also, an imbalance in adenosinergic analgesic signaling in sensory neurons such as the downregulation of prostatic acid phosphatase and adenosine A1 receptors, which colocalized with TRPV1 as a membrane microdomain also correlated with the development of mechanical allodynia. Collectively, TRPV1 depletion-induced mechanical allodynia involves a complicated cascade of cellular signaling alterations.

Early versus Late Surgical Decompression for Traumatic Spinal Cord Injury on Neurological Recovery: A Systematic Review and Meta-Analysis.

This study aimed to investigate whether early surgical decompression was associated with favorable neurological recovery in patients with traumatic spinal cord injury (tSCI). We searched PubMed and Embase from the database inception through December 2020 and selected studies comparing the impact of early versus late surgical decompression on neurological recovery as assessed by American Spinal Injury Association Impairment Scale (AIS) for adult patients sustaining tSCI. We pooled the effect estimates in random-effects models and quantified the heterogeneity by the I2 statistics. Subgroup analysis and meta-regression analysis was conducted to identify significant outcome moderator. We included 26 studies involving 3574 patients in the meta-analysis. The pooled results demonstrated significant association between early surgical decompression and an improvement of at least one AIS grade (odds ratio [OR], 1.85; 95% confidence interval [CI], 1.41-2.41; I2, 48.06%). The benefits of early surgical decompression were consistently observed across different subgroups, including patients with cervical or thoracolumbar injury and patients with complete or incomplete injury. The meta-regression analysis indicated that cut-off timing defining early versus late decompression was a significant effect moderator, with early decompression performed before post-tSCI 8 or 12 h associated with greatest benefits (OR, 3.37; 95% CI, 1.74-6.50; I2, 53.52%). No obvious publication bias was detected by the funnel plot. In conclusion, early surgical decompression was associated with favorable neurological recovery for tSCI patients. However, there was a lack of high-quality evidence and the results need further examination.

Genetic loss-of-function of activating transcription factor 3 but not C-type lectin member 5A prevents diabetic peripheral neuropathy.

We investigated the mediating roles of activating transcription factor 3 (ATF3), an injury marker, or C-type lectin member 5A (CLEC5A), an inflammatory response molecule, in the induction of endoplasmic reticulum (ER) stress and neuroinflammation in diabetic peripheral neuropathy in ATF3 and CLEC5A genetic knockout (aft3-/- and clec5a-/-, respectively) mice. ATF3 was expressed intranuclearly and was upregulated in mice with diabetic peripheral neuropathy (DN) and clec5a-/- mice. The DN and clec5a-/- groups also exhibited neuropathic behavior, but not in the aft3-/- group. The upregulation profiles of cytoplasmic polyadenylation element-binding protein, a protein translation-regulating molecule, and the ER stress-related molecules of inositol-requiring enzyme 1α and phosphorylated eukaryotic initiation factor 2α in the DN and clec5a-/- groups were correlated with neuropathic behavior. Ultrastructural evidence confirmed ER stress induction and neuroinflammation, including microglial enlargement and proinflammatory cytokine release, in the DN and clec5a-/- mice. By contrast, the induction of ER stress and neuroinflammation did not occur in the aft3-/- mice. Furthermore, the mRNA of reactive oxygen species-removing enzymes such as superoxide dismutase, heme oxygenase-1, and catalase were downregulated in the DN and clec5a-/- groups but were not changed in the aft3-/- group. Taken together, the results indicate that intraneuronal ATF3, but not CLEC5A, mediates the induction of ER stress and neuroinflammation associated with diabetic neuropathy.

A retrospective study on the therapeutic effects of sodium bicarbonate for adult in-hospital cardiac arrest.

To investigate whether the effects of sodium bicarbonate (SB) during cardiopulmonary resuscitation (CPR) would be influenced by blood pH and administration timing. Adult patients experiencing in-hospital cardiac arrest (IHCA) from 2006 to 2015 were retrospectively screened. Early intra-arrest blood gas data were obtained within 10 min of CPR. Multivariable logistic regression analysis and generalised additive models were used for effect estimation and data exploration, respectively. A total of 1060 patients were included. Only 59 patients demonstrated favourable neurological status at hospital discharge. Blood pH ≤ 7.18 was inversely associated with favourable neurological outcome (odds ratio [OR], 0.24; 95% confidence interval [CI], 0.11-0.52; p value < 0.001) while SB use was not. In the interaction analysis for favourable neurological outcome, significant interactions were noted between SB use and time to SB (SB use × time to SB ≥ 20 min; OR 6.16; 95% CI 1.42-26.75; p value = 0.02). In the interaction analysis for survival to hospital discharge, significant interactions were noted between SB use and blood pH (Non-SB use × blood pH > 7.18; OR 1.56; 95% CI 1.01-2.41; p value = 0.05). SB should not be empirically administered for patients with IHCA since its effects may be influenced by blood pH and administration timing.

Clinical Features of Emergency Department Patients from Early COVID-19 Pandemic that Predict SARS-CoV-2 Infection: Machine-learning Approach.

INTRODUCTION: Within a few months coronavirus disease 2019 (COVID-19) evolved into a pandemic causing millions of cases worldwide, but it remains challenging to diagnose the disease in a timely fashion in the emergency department (ED). In this study we aimed to construct machine-learning (ML) models to predict severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection based on the clinical features of patients visiting an ED during the early COVID-19 pandemic. METHODS: We retrospectively collected the data of all patients who received reverse transcriptase polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 at the ED of Baylor Scott & White All Saints Medical Center, Fort Worth, from February 23-May 12, 2020. The variables collected included patient demographics, ED triage data, clinical symptoms, and past medical history. The primary outcome was the confirmed diagnosis of COVID-19 (or SARS-CoV-2 infection) by a positive RT-PCR test result for SARS-CoV-2, and was used as the label for ML tasks. We used univariate analyses for feature selection, and variables with P<0.1 were selected for model construction. Samples were split into training and testing cohorts on a 60:40 ratio chronologically. We tried various ML algorithms to construct the best predictive model, and we evaluated performances with the area under the receiver operating characteristic curve (AUC) in the testing cohort. RESULTS: A total of 580 ED patients were tested for SARS-CoV-2 during the study periods, and 98 (16.9%) were identified as having the SARS-CoV-2 infection based on the RT-PCR results. Univariate analyses selected 21 features for model construction. We assessed three ML methods for performance: of the three methods, random forest outperformed the others with the best AUC result (0.86), followed by gradient boosting (0.83) and extra trees classifier (0.82). CONCLUSION: This study shows that it is feasible to use ML models as an initial screening tool for identifying patients with SARS-CoV-2 infection. Further validation will be necessary to determine how effectively this prediction model can be used prospectively in clinical practice.

Intraosseous versus intravenous vascular access during cardiopulmonary resuscitation for out-of-hospital cardiac arrest: a systematic review and meta-analysis of observational studies.

INTRODUCTION: This study is aimed to investigate the association of intraosseous (IO) versus intravenous (IV) route during cardiopulmonary resuscitation (CPR) with outcomes after out-of-hospital cardiac arrest (OHCA). METHODS: We systematically searched PubMed, Embase, Cochrane Library and Web of Science from the database inception through April 2020. Our search strings included designed keywords for two concepts, i.e. vascular access and cardiac arrest. There were no limitations implemented in the search strategy. We selected studies comparing IO versus IV access in neurological or survival outcomes after OHCA. Favourable neurological outcome at hospital discharge was pre-specified as the primary outcome. We pooled the effect estimates in random-effects models and quantified the heterogeneity by the I2 statistics. Time to intervention, defined as time interval from call for emergency medical services to establishing vascular access or administering medications, was hypothesized to be a potential outcome moderator and examined in subgroup analysis with meta-regression. RESULTS: Nine retrospective observational studies involving 111,746 adult OHCA patients were included. Most studies were rated as high quality according to Newcastle-Ottawa Scale. The pooled results demonstrated no significant association between types of vascular access and the primary outcome (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.27-1.33; I2, 95%). In subgroup analysis, time to intervention was noted to be positively associated with the pooled OR of achieving the primary outcome (OR: 3.95, 95% CI, 1.42-11.02, p: 0.02). That is, when the studies not accounting for the variable of "time to intervention" in the statistical analysis were pooled together, the meta-analytic results between IO access and favourable outcomes would be biased toward inverse association. No obvious publication bias was detected by the funnel plot. CONCLUSIONS: The meta-analysis revealed no significant association between types of vascular access and neurological outcomes at hospital discharge among OHCA patients. Time to intervention was identified to be an important outcome moderator in this meta-analysis of observation studies. These results call for the need for future clinical trials to investigate the unbiased effect of IO use on OHCA CPR.

Peripheral Neuropathic Pain: From Experimental Models to Potential Therapeutic Targets in Dorsal Root Ganglion Neurons.

Neuropathic pain exerts a global burden caused by the lesions in the somatosensory nerve system, including the central and peripheral nervous systems. The mechanisms of nerve injury-induced neuropathic pain involve multiple mechanisms, various signaling pathways, and molecules. Currently, poor efficacy is the major limitation of medications for treating neuropathic pain. Thus, understanding the detailed molecular mechanisms should shed light on the development of new therapeutic strategies for neuropathic pain. Several well-established in vivo pain models were used to investigate the detail mechanisms of peripheral neuropathic pain. Molecular mediators of pain are regulated differentially in various forms of neuropathic pain models; these regulators include purinergic receptors, transient receptor potential receptor channels, and voltage-gated sodium and calcium channels. Meanwhile, post-translational modification and transcriptional regulation are also altered in these pain models and have been reported to mediate several pain related molecules. In this review, we focus on molecular mechanisms and mediators of neuropathic pain with their corresponding transcriptional regulation and post-translational modification underlying peripheral sensitization in the dorsal root ganglia. Taken together, these molecular mediators and their modification and regulations provide excellent targets for neuropathic pain treatment.

Onsite telemedicine strategy for coronavirus (COVID-19) screening to limit exposure in ED.

Coronavirus (severe acute respiratory syndrome coronavirus 2) outbreak is a public health emergency and a global pandemic. During the present coronavirus disease (COVID-19) crisis, telemedicine has been recommended to screen suspected patients to limit risk of exposure and maximise medical staff protection. We constructed the protective physical barrier with telemedicine technology to limit COVID-19 exposure in ED. Our hospital is an urban community hospital with annual ED volume of approximately 50 000 patients. We equipped our patient exam room with intercom and iPad for telecommunication. Based on our telemedicine screening protocol, physician can conduct a visual physical examination on stable patients via intercom or videoconference. Telemedicine was initially used to overcome the physical barrier between patients and physicians. However, our protocol is designed to create a protective physical barrier to protect healthcare workers and enhance efficiency in ED. The implementation can be a promising protocol in making ED care more cost-effective and efficient during the COVID-19 pandemic and beyond.

Association of ultrasound-related interruption during cardiopulmonary resuscitation with adult cardiac arrest outcomes: A video-reviewed retrospective study.

OBJECTIVES: To determine the association of focused transthoracic echocardiography (ECHO) related interruption during cardiopulmonary resuscitation (CPR) with patient outcomes in the Emergency Department (ED). METHODS: This was a retrospective, single center, cohort study, conducted in an urban community teaching ED. Eligible study subjects were adult patients in the ED with sustained cardiac arrest. Exclusion criteria include traumatic cardiac arrest and age less than 18. All resuscitations were video recorded and were subsequently reviewed by 2 study investigators. The no-flow time from chest compression interruption was analyzed using video review and separated into ECHO-related and non-ECHO related. Our primary outcome was patient survival to hospital discharge and the secondary outcome was the rate of return of spontaneous circulation (ROSC). Multivariate logistic regression analyses were performed to examine the associations between independent variables and outcomes. RESULTS: From January 2016 to May 2017, a total of 210 patients were included for final analysis. The median total no-flow time observed on video was 99.5 s (IQR: 54.0-160.0 s). Among these, a median of 26.5 s (IQR: 0.0-59.0 s) was ECHO-related and a median of 60.5 s (IQR: 34.0-101.9) was non-ECHO-related. The ECHO-related no-flow time between 77 and 122 s (OR: 7.31, 95 % confidence interval [CI]: 1.59-33.59; p-value = 0.01) and ECHO-related interruption ≦ 2 times (OR: 8.22, 95% CI: 1.51-44.64; p-value = 0.01) were positively associated with survival to hospital discharge. ECHO-related interruption ≦ 2 times (OR: 5.55, 95% CI: 2.44-12.61; p-value < 0.001) was also positively associated with ROSC. CONCLUSION: Short ECHO-related interruption during CPR was positively associated with ROSC and survival to hospital discharge. While ECHO can be a valuable diagnostic tool during CPR, the no-flow time associated with ECHO should be minimized.

Activating transcription factor 3 modulates protein kinase C epsilon activation in diabetic peripheral neuropathy.

BACKGROUND: Skin denervation that develops in patients with diabetes mellitus as a neuropathic manifestation is known as diabetic peripheral neuropathy (DPN). Skin denervation is parallel to neuronal injuries that alter intracellular signaling. To date, the correlation between nerve injury and the activation of intracellular responses to neuropathic manifestations has not been elucidated; specifically, whether activating transcription factor 3 (ATF3) is responsible for neuronal injury and a critical molecule that modulates the activation of intracellular protein kinase C epsilon (p-PKCε) and pain development in DPN is a crucial question. METHODS: To address, ATF3 knockout (atf3 -/- group, C57/B6 genetic background) and wild-type mice (atf3+/+ group) received a single dose of streptozotocin (200 mg/kg) to generate a mouse model of DPN. RESULTS: Both atf3+/+ and atf3 -/- mice exhibited hyperglycemia and the same pathology of skin denervation at posttreatment month 2, but only atf3+/+ mice developed thermal hyperalgesia (P<0.001) and mechanical allodynia (P=0.002). The atf3+/+ group, but not the atf3 -/- group, had preferential ATF3 upregulation on p-PKCε(+) neurons with a ratio of 37.7%±6.1% in p-PKCε(+):ATF3(+) neurons (P<0.001). In addition, B-cell lymphoma-extra large (Bcl-XL), an antiapoptotic Bcl2 family protein, exhibited parallel patterns to p-PKCε (ie, Bcl-XL upregulation was reversed in atf3 -/- mice). These two molecules were colocalized and increased by approximately two-fold in the atf3+/+ group compared with the atf3 -/- group (30.0%±3.4% vs 13.7% ± 6.2%, P=0.003). Furthermore, linear analysis results showed that the densities of p-PKCε and Bcl-XL had a reverse linear relationship with the degrees of thermal hyperalgesia and mechanical allodynia. CONCLUSION: Collectively, this report suggested that ATF3 is a critical upstream molecule that modulates p-PKCε and Bcl-XL expression, which consequently mediated the development of neuropathic manifestation in DPN.

Treatment with methyl-ß-cyclodextrin prevents mechanical allodynia in resiniferatoxin neuropathy in a mouse model.

Specialized microdomains which have cholesterol-rich membrane regions contain transient receptor potential vanilloid subtype 1 (TRPV1) are involved in pain development. Our previous studies have demonstrated that the depletion of prostatic acid phosphatase (PAP) - a membrane-bound ectonucleotidase -- and disordered adenosine signaling reduce the antinociceptive effect. The role of membrane integrity in the PAP-mediated antinociceptive effect in small-fiber neuropathy remains unclear, especially with respect to whether TRPV1 and PAP are colocalized in the same microdomain which is responsible for PAP-mediated antinociception. Immunohistochemistry was conducted on the dorsal root ganglion to identify the membrane compositions, and pharmacological interventions were conducted using methyl-ß-cyclodextrin (MßC) - a membrane integrity disruptor that works by depleting cholesterol - in pure small-fiber neuropathy with resiniferatoxin (RTX). Immunohistochemical evidence indicated that TRPV1 and PAP were highly colocalized with flotillin 1 (66.7%±9.7%) and flotillin 2 (73.7%±6.0%), which reside in part in the microdomain. MßC mildly depleted PAP, which maintained the ability to hydrolyze phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and delayed the development of mechanical allodynia. MßC treatment had no role in thermal transduction and neuronal injury following RTX neuropathy. In summary, this study demonstrated the following: (1) membrane cholesterol depletion preserves PAP-mediated antinociception through PI(4,5)P2 hydrolysis and (2) pain hypersensitivity that develops after TRPV1(+) neuron depletion-mediated neurodegeneration following RTX neuropathy is attributable to the downregulation of PAP analgesic signaling.

Greater ultrasonographic changes in pediatric moyamoya patients compared with adults after indirect revascularization surgeries.

OBJECTIVEPediatric and adult patients with moyamoya disease experience similar clinical benefits from indirect revascularization surgeries, but there are still debates about age-related angiographic differences of the collaterals established after surgery. The goal of this study was to assess age-related differences on ultrasonography before and after indirect revascularization surgeries in moyamoya patients, focusing on some ultrasonographic parameters known to be correlated with the collaterals supplied by the external carotid artery (ECA).METHODSThe authors prospectively included moyamoya patients (50 and 26 hemispheres in pediatric and adult patients, respectively) who would undergo indirect revascularization surgery. Before surgery and at 1, 3, and 6 months after surgery, the patients underwent ultrasonographic examinations. The ultrasonographic parameters included peak-systolic velocity (PSV), end-diastolic velocity (EDV), resistance index (RI), and flow volume (FV) measured in the ECA, superficial temporal artery (STA), and internal carotid artery on the operated side. The mean values, absolute changes, and percentage changes of these parameters were compared between the pediatric and adult patients. Logistic regression analysis was used to clarify the determinants affecting postoperative EDV changes in the STA.RESULTSBefore surgery, the adult patients had mean higher EDV and lower RI in the STA and ECA than the pediatric group (all p < 0.05). After surgery, the pediatric patients had greater changes (absolute and percentage changes) in the PSV, EDV, RI, and FV in the STA and ECA (all p < 0.05). The factors affecting postoperative EDV changes in the STA at 6 months were age (p = 0.006) and size of the revascularization area (i.e., revascularization in more than the temporal region vs within the temporal region; p = 0.009). Pediatric patients who received revascularization procedures in more than the temporal region had higher velocities (PSV and EDV) in the STA than those who received revascularization within the temporal region (p < 0.05 at 1-6 months), but such differences were not observed in the adult group.CONCLUSIONSThe greater changes of these parameters in the STA and ECA in pediatric patients than in adults after indirect revascularization surgeries indicated that pediatric patients might have a greater increase of collaterals postoperatively than adults. Pediatric patients who undergo revascularization in more than the temporal region might have more collaterals than those who undergo revascularization within the temporal region.

Tumor necrosis factor-α mediated pain hypersensitivity through Ret receptor in resiniferatoxin neuropathy.

Neurogenic inflammation is an onset characteristic of small fiber neuropathy (SFN), which is attributed to neuropathic manifestations. Tumor necrosis factor-α (TNFα) is a cytokine that mainly mediates neurogenic inflammation through the ligand receptor TNF receptor 1 (TNFR1), and targeting TNFα/TNFR1 signaling is a direction toward treating inflammatory diseases and injury-induced neuropathy. However, the relationships between TNFα/TNFR1 signaling and Ret signaling, which mediates pain hypersensitivity, remains elusive. This study used resiniferatoxin (RTX), an ultrapotent analog of capsaicin, to generate a mouse model of SFN, leading to marked hindpaw edema (p = 0.013) and parallel the release of TNFα (p = 0.014), which was associated with the upregulation of Ret(+) neurons (p = 0.0043) and partial depletion of TNFR1 caused by colocalization with TRPV1 depleted by RTX. Pharmacological intervention of TNFα with etanercept (Enbrel®, Wyeth), a clinical application of TNFα blockers, relieved neurogenic inflammation and caused a reduction in hindpaw thickness (p = 0.03) and TNFα releases (p = 0.01), which were determined to be associated with the normalization of mechanical allodynia (p = 0.22). The extraction of either TNFR1(+) or Ret(+) neurons from total of TNFR1(+):Ret(+) neurons indicated that TNFR1(-)/Ret(+) neurons correlated with the mechanical threshold in an antiparallel fashion (r = -0.84, p < 0.0001) but had no relationship with thermal latencies. This study confirmed that TNFα rather than TNFα mediated neuropathic manifestation through the Ret receptor, specifically mechanical allodynia in RTX neuropathy.

Downregulation of adenosine and adenosine A1 receptor contributes to neuropathic pain in resiniferatoxin neuropathy.

The neurochemical effects of adenosine signaling in small-fiber neuropathy leading to neuropathic pain are yet to be explored in a direct manner. This study examined this system at the level of ligand (through the ectonucleotidase activity of prostatic acid phosphatase [PAP]) and adenosine A1 receptors (A1Rs) in resiniferatoxin (RTX) neuropathy, a peripheral neurodegenerative disorder that specifically affects nociceptive nerves expressing transient receptor potential vanilloid type 1 (TRPV1). We conducted immunohistochemistry on dorsal root ganglion (DRG) neurons, high-performance liquid chromatography for functional assays, and pharmacological interventions to alter PAP and A1Rs in mice with RTX neuropathy. In DRG of RTX neuropathy, PAP(+) neurons were reduced compared with vehicle-treated mice (P = 0.002). Functionally, PAP ectonucleotidase activity was consequently reduced (ie, the content of adenosine in DRG, P = 0.012). PAP(+) neuronal density was correlated with the degree of mechanical allodynia, which was reversed by intrathecal (i.t.) lumbar puncture injection of recombinant PAP with a dose-dependent effect. Furthermore, A1Rs were downregulated (P = 0.002), and this downregulation was colocalized with the TRPV1 receptor (31.0% ± 2.8%). Mechanical allodynia was attenuated in a dose-dependent response by i.t. injection of the A1R ligand, adenosine; however, no analgesia was evident when an exogenous adenosine was blocked by A1R antagonist. This study demonstrated dual mechanisms of neuropathic pain in TRPV1-induced neuropathy, involving a reduced adenosine system at both the ligand (adenosine) and receptor (A1Rs) levels.

Establishing a Mouse Model of a Pure Small Fiber Neuropathy with the Ultrapotent Agonist of Transient Receptor Potential Vanilloid Type 1.

Patients with diabetes mellitus (DM) or those experiencing the neurotoxic effects of chemotherapeutic agents may develop sensation disorders due to degeneration and injury of small-diameter sensory neurons, referred to as small fiber neuropathy. Present animal models of small fiber neuropathy affect both large- and small-diameter sensory fibers and thus create a neuropathology too complex to properly assess the effects of injured small-diameter sensory fibers. Therefore, it is necessary to develop an experimental model of pure small fiber neuropathy to adequately examine these issues. This protocol describes an experimental model of small fiber neuropathy specifically affecting small-diameter sensory nerves with resiniferatoxin (RTX), an ultrapotent agonist of transient receptor potential vanilloid type 1 (TRPV1), through a single dose of intraperitoneal injection, referred to as RTX neuropathy. This RTX neuropathy showed pathological manifestations and behavioral abnormalities that mimic the clinical characteristics of patients with small fiber neuropathy, including intraepidermal nerve fiber (IENF) degeneration, specifically injury in small-diameter neurons, and induction of thermal hypoalgesia and mechanical allodynia. This protocol tested three doses of RTX (200, 50, and 10 µg/kg, respectively) and concluded that a critical dose of RTX (50 µg/kg) is required for the development of typical small fiber neuropathy manifestations, and prepared a modified immunostaining procedure to investigate IENF degeneration and neuronal soma injury. The modified procedure is fast, systematic, and economic. Behavioral evaluation of neuropathic pain is critical to reveal the function of small-diameter sensory nerves. The evaluation of mechanical thresholds in experimental rodents is particularly challenging and this protocol describes a customized metal mesh that is suitable for this type of assessment in rodents. In summary, RTX neuropathy is a new and easily established experimental model to evaluate the molecular significance and intervention underlying neuropathic pain for the development of therapeutic agents.

Nerve Decompression Improves Spinal Synaptic Plasticity of Opioid Receptors for Pain Relief.

Nerve decompression is an essential therapeutic strategy for pain relief clinically; however, its potential mechanism remains poorly understood. Opioid analgesics acting on opioid receptors (OR) within the various regions of the nervous system have been used widely for pain management. We therefore hypothesized that nerve decompression in a neuropathic pain model of chronic constriction injury (CCI) improves the synaptic OR plasticity in the dorsal horn, which is in response to alleviate pain hypersensitivity. After CCI, the Sprague-Dawley rats were assigned into Decompression group, in which the ligatures around the sciatic nerve were removed at post-operative week 4 (POW 4), and a CCI group, in which the ligatures remained. Pain hypersensitivity, including thermal hyperalgesia and mechanical allodynia, was entirely normalized in Decompression group within the following 4 weeks. Substantial reversal of mu- and delta-OR immunoreactive (IR) expressions in Decompression group was detected in primary afferent terminals in the dorsal horn. In Decompression group, mu-OR antagonist (CTOP, D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 [Disulfide Bridge: 2-7]) and delta-OR antagonist (NTI, 17-(cyclopropylmethyl)-6,7-dehydro-4,5α-epoxy-3,14-dihydroxy-6,7-2',3'-indolomorphinan hydrochloride) re-induced pain hypersensitivity by intrathecal administration in a dose-responsive manner. Additionally, mu-OR agonist (DAMGO, [D-Ala2, NMe-Phe4, Gly-ol5]-enkephalin) and delta-OR agonist (SNC80, ((+)-4-[(αR)-α-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethyl-benzamide) were administrated intrathecally to attenuating CCI-induced chronic and acute pain hypersensitivity dose-dependently. Our current results strongly suggested that nerve decompression provides the opportunity for improving the synaptic OR plasticity in the dorsal horn and pharmacological blockade presents a novel insight into the therapeutic strategy for pain hypersensitivity.

Distinct TrkA and Ret modulated negative and positive neuropathic behaviors in a mouse model of resiniferatoxin-induced small fiber neuropathy.

Neurotrophic factors and their corresponding receptors play key roles in the maintenance of different phenotypic dorsal root ganglion (DRG) neurons, the axons of which degenerate in small fiber neuropathy, leading to various neuropathic manifestations. Mechanisms underlying positive and negative symptoms of small fiber neuropathy have not been systematically explored. This study investigated the molecular basis of these seemingly paradoxical neuropathic behaviors according to the profiles of TrkA and Ret with immunohistochemical and pharmacological interventions in a mouse model of resiniferatoxin (RTX)-induced small fiber neuropathy. Mice with RTX neuropathy exhibited thermal hypoalgesia and mechanical allodynia, reduced skin innervation, and altered DRG expression profiles with decreased TrkA(+) neurons and increased Ret(+) neurons. RTX neuropathy induced the expression of activating transcription factor 3 (ATF3), and ATF3(+) neurons were colocalized with Ret but not with TrkA (P<0.001). As a neuroprotectant, 4-Methylcatechol (4MC) promoted skin reinnervation partially with correlated reversal of the neuropathic behaviors and altered neurochemical expression. Gambogic amide, a selective TrkA agonist, normalized thermal hypoalgesia, and GW441756, a TrkA kinase inhibitor, induced thermal hypoalgesia, which was already reversed by 4MC. Mechanical allodynia was reversed by a Ret kinase inhibitor, AST487, which induced thermal hyperalgesia in naïve mice. The activation of Ret signaling by XIB4035 induced mechanical allodynia and thermal hypoalgesia in RTX neuropathy mice in which the neuropathic behaviors were previously normalized by 4MC. Distinct neurotrophic factor receptors, TrkA and Ret, accounted for negative and positive neuropathic behaviors in RTX-induced small fiber neuropathy, respectively: TrkA for thermal hypoalgesia and Ret for mechanical allodynia and thermal hypoalgesia.