Levels of preoperative cerebrospinal fluid pro-inflammatory mediators and chronic pain after total knee arthroplasty surgery.

BACKGROUND: Patients undergoing total knee arthroplasty (TKA) surgery are at high risk of chronic postsurgical pain (CPSP). Accumulating evidence suggests an active role of neuroinflammation in chronic pain. However, its role in the progression to CPSP following TKA surgery remains unanswered. Here, we examined the associations between preoperative neuroinflammatory states and pre- and postsurgical chronic pain in TKA surgery. METHODS: The data of 42 patients undergoing elective TKA surgery for chronic knee arthralgia at our hospital were analyzed in this prospective study. Patients completed the following questionnaires: brief pain inventory (BPI), hospital anxiety and depression scale, painDETECT, and pain catastrophizing scale (PCS). Cerebrospinal fluid (CSF) samples were collected preoperatively and concentrations of IL-6, IL-8, TNF, fractalkine, and CSF-1 were measured by electrochemiluminescence multiplex immunoassay. CPSP severity was ascertained, using the BPI, 6 months postsurgery. RESULTS: While no significant correlation was observed between the preoperative CSF mediator levels and preoperative pain profiles, the preoperative fractalkine level in the CSF showed a significant correlation with CPSP severity (Spearman's rho = -0.525; p = .002). Furthermore, multivariate linear regression analysis revealed that the preoperative PCS score (standardized ß coefficient [ß]: .11; 95% confidence interval [CI]: 0.06-0.16; p < .001) and CSF fractalkine level (ß: -.62; 95% CI: -1.10 to -0.15; p = .012) were independent predictors of CPSP severity 6 months after TKA surgery. CONCLUSIONS: We identified the CSF fractalkine level as a potential predictor for CPSP severity following TKA surgery. In addition, our study provided novel insights into the potential role of neuroinflammatory mediators in the pathogenesis of CPSP.

Decreased Interoceptive Awareness as a Risk Factor for Moderate to Severe Pain in Japanese Full-Time Workers: A Longitudinal Cohort Study.

Interoceptive awareness, the conscious perception of internal bodily states, is a key construct of mind-body interaction. Decreases in interoceptive awareness, as measured by the Multidimensional Assessment of Interoceptive Awareness (MAIA), are found in chronic pain patients. In this study, we explored whether a specific aspect of interoceptive awareness is a risk for the onset and chronicity of pain. A longitudinal cohort study was conducted in 2018 and 2020 among a sample of full-time workers in an industrial manufacturing company in Japan. Participants completed a questionnaire on pain intensity, MAIA, exercise habits, kinesiophobia, psychological distress and work stress. Principal component analyses using the MAIA identified two principal components: self-control and emotional stability. Low emotional stability was associated with the prevalence of moderate to severe pain in 2020 among people with mild or no pain in 2018 (p < 0.01). Lack of exercise habits were associated with the prevalence of moderate to severe pain in 2020 among people with pain in 2018 (p < 0.01). Furthermore, exercise habits were associated with reduction in kinesiophobia among people with moderate to severe pain in 2018 (p = 0.047). Overall, these findings indicate that low emotional stability may be a risk for the onset of moderate to severe pain; lack of exercise habits may sustain kinesiophobia and be a risk for the chronicity of pain.

Effect of repeated transforaminal epidural low-dose dexamethasone injections on glucose profiles of diabetic and non-diabetic patients with low back pain.

PURPOSE: We aimed to investigate the effect of repeated transforaminal epidural low-dose dexamethasone injections on glucose profiles and pituitary-adrenal axis functions of diabetic and non-diabetic patients with low back pain. METHODS: A total of 28 patients (ten diabetic [DM group] and 18 non-diabetic patients [non-DM group]) with low back pain were followed-up. Transforaminal epidural low-dose dexamethasone (1.65 mg) injections were repeated every 7-14 days for 8 weeks. Fasting blood sugar (FBS), hemoglobin A1c (HbA1c), morning plasma adrenocorticotropin (ACTH), and cortisol levels were measured at baseline and during the 8-week follow-up period. RESULTS: There were no significant changes in FBS and HbA1c levels between baseline and 8-week follow-up period in both DM and non-DM groups (difference in FBS [95% confidence Interval, CI]: - 0.6 mg/dL [- 6.4, 5.1], p = 0.83 in the non-DM group, - 0.2 mg/dL [- 26.2, 25.8], p = 0.99 in the DM group; difference in HbA1c [95% CI] - 0.02% [- 0.1, 0.1], p = 0.69 in the non-DM group, 0.04% [- 0.3, 0.4], p = 0.79 in the DM group). There were no significant longitudinal changes in ACTH and cortisol levels (ACTH, p = 0.38 [baseline vs. 8 week], p = 0.58 [non-DM vs. DM]; cortisol, p = 0.52 [baseline vs. 8 week], p = 0.90 [non-DM vs. DM]). CONCLUSIONS: Repeated transforaminal epidural low-dose dexamethasone injections provided no significant elevations in blood glucose or suppression of the pituitary-adrenal axis for two months from the first injection in both diabetic and non-diabetic patients. Our results indicate the intermediate-term safety of repeated transforaminal epidural low-dose dexamethasone injections with regard to the effect on glucose profile and pituitary-adrenal axis functions.

Improvement in Disability Mediates the Effect of Self-Efficacy on Pain Relief in Chronic Low Back Pain Patients with Exercise Therapy.

Background: The biopsychosocial mechanism by which exercise leads to improvement in chronic low back pain (CLBP) remains unstudied. This prospective cohort study was performed to examine the effectiveness of exercise on pain, disability, and psychological status for CLBP. We also tested path analytic models in which changes in these variables were included. Methods: CLBP patients who visited the Interdisciplinary Pain Center of Keio University Hospital from July 2018 to April 2020 were included. The propensity score matching was performed between patients who underwent exercise (the exercise group) and those who did not (the control group). At the first visit and at the 3-month follow-up, pain (Numerical Rating Scale (NRS)), disability (Pain Disability Assessment Scale (PDAS)), and psychological status (Pain Self-Efficacy Questionnaire (PSEQ), and Pain Catastrophizing Scale (PCS)) were assessed. Changes in pain and disability at the follow-up were compared between the groups. The relationships between changes in pain, disability, and psychological variables were examined using Pearson's correlation and mediation analysis. Results: A significantly larger decrease in the PDAS was observed in the exercise group (N = 49) than in the control (N = 49) (p < 0.05). Increased PSEQ scores were significantly correlated with decreased NRS scores in both groups. In the exercise group, decreased PDAS fully mediated the relationship between increased PSEQ and decreased NRS (P < 0.05). Conclusion: Exercise improved disability, and the improved disability by exercise mediated the effect of increased self-efficacy on pain relief in CLBP patients.

A Cross-Sectional Study of the Impact of Pain Severity on Absenteeism and Presenteeism Among Japanese Full-Time Workers.

INTRODUCTION: Pain is known to have a high impact on work performance, but there are several confounding factors, such as stress and mental issues. Little is known about the impact of pain severity on work performance when adjusted for such confounding factors. The aim of this study was to identify the effect of pain severity on absence from work (absenteeism) and reduced performance (presenteeism). METHODS: A cross-sectional study was conducted among full-time workers at an industrial manufacturing company in Japan. Participants were assessed using a self-reported questionnaire, including work performance evaluations, pain characteristics, pain-related fear, psychological distress, stress at the workplace and home, workaholism, and self-awareness. Principal component analysis was utilized to decrease the dimensions of the measures, and orthogonal rotation was performed on identified components with an eigenvalue > 1.0. Multivariable logistic regression analyses were performed to determine the association between pain severity and absenteeism and presenteeism, and were adjusted for confounding factors. We also analyzed the association between pain intensity and presenteeism using multivariable logistic regression analyses. RESULTS: A total of 349 workers participated in the study. Six principal components were identified as confounding factors: work stress, regulation, mental instability, less support, home stress, and life dissatisfaction. Multivariable logistic regression analyses showed significant associations of moderate to severe pain with absenteeism (p = 0.02) and low and high presenteeism (p = 0.004 and 0.009, respectively), adjusted for age, sex, body mass index, short sleep, and the six principal components. Pain intensity was also significantly associated with low and high presenteeism (p = 0.002 and 0.014, respectively) in people with pain. CONCLUSIONS: Pain severity is a risk factor for absenteeism and presenteeism, even if workers have comorbid psychological stress or mental health problems.

Association of work performance and interoceptive awareness of 'body trusting' in an occupational setting: a cross-sectional study.

OBJECTIVES: Work performance has been known to be influenced by both psychological stress (mind) and physical conditions (body). The aim of this study was to investigate the association between work performance and 'body trusting', which is a dimension of interoceptive awareness representing mind-body interactions. METHODS: A cross-sectional study was conducted among a sample of workers in an industrial manufacturing company in Japan. Participants were assessed with a self-reported questionnaire including evaluations of work performance, body trusting, psychological distress, pain persistence, workplace and home stressors, and workaholism. Participants' sociodemographic, health and lifestyle characteristics were collected from their annual health check data. The association between work performance and body trusting was examined using multivariable regression analyses in the overall sample and in a subsample of people with pain. RESULTS: A total of 349 workers participated in the study. A significant association between work performance and body trusting was observed, with higher body trusting representing higher work performance. The association was significant after controlling for psychological distress, workplace and home stress, workaholism and participants' characteristics (p<0.001). Compared with people without pain (n=126, 36.1%), people with pain (n=223, 63.9%) showed less body trusting, which was associated with decreased work performance after controlling for pain-related variables (p<0.001). CONCLUSIONS: Workers with higher body trusting showed higher work performance, even after controlling for various influencing factors. Body trusting may be an important target to promote work performance and to prevent loss of performance induced by health problems.

Effectiveness of Duloxetine for Postsurgical Chronic Neuropathic Disorders after Spine and Spinal Cord Surgery.

STUDY DESIGN: This is a retrospective observational study with an outpatient setting. PURPOSE: This study aimed to describe the effects of duloxetine (DLX) administration for postsurgical chronic neuropathic disorders (both pain and numbness) following spinal surgery in patients without depression. OVERVIEW OF LITERATURE: Although several reports indicated the potential of DLX to effectively treat postoperative symptoms as a perioperative intervention, there have been no reports of its positive effect on postsurgical chronic neuropathic disorders. METHODS: A total of 24 patients with postsurgical chronic pain and/or numbness Numeric Rating Scale (NRS) scores of ≥4 were enrolled. All patients underwent spine or spinal cord surgery at Keio University Hospital and received daily administration of DLX for more than 3 months. The mean postoperative period before the first administration of DLX was 35.5±57.0 months. DLX was administered for more than 3 months at a dose of 20, 40, or 60 mg/day, and the degree of pain and numbness was evaluated using the NRS before administration and 3 months after administration. Effectiveness was defined as more than a 2-point decrease in the NRS score following administration. RESULTS: In terms of the type of symptoms, 15 patients experienced only numbness, eight experienced both pain and numbness, and one experienced only pain. Of the 24 patients, 19 achieved effective relief with DLX. DLX was effective for all patients with postsurgical chronic pain (n=9), and it reduced postsurgical chronic numbness in 18 of 23 patients. No significant difference was observed in background spinal disorders. DLX was not effective for five patients who complained only of postsurgical chronic numbness. CONCLUSIONS: This study reports the effectiveness of DLX for postsurgical chronic neuropathic disorders. Although DLX reduced postsurgical chronic pain (efficacy rate=100%) and numbness (78.3%) in certain patients, further investigation is needed to determine its optimal use.

Retraction Note: Desflurane anesthesia worsens emergence agitation in adult patients undergoing thyroid surgery compared to sevoflurane anesthesia.

The Editor-in-Chief has retracted this article [1]. The ethics committee approval was granted for an observational study and the need for patient consent was waived. However, the study design described is a randomized controlled trial and therefore patient consent should have been obtained. All authors agree with this retraction.

Aberrant resting-state functional connectivity of the dorsolateral prefrontal cortex to the anterior insula and its association with fear avoidance belief in chronic neck pain patients.

Chronic neck pain (CNP), a global health problem, involves a large amount of psychological and socioeconomic burdens. Not only physical causes but also behavioral disorders such as a fear-avoidance belief (FAB) can associate with the chronicity of neck pain. However, functional brain mechanisms underlying CNP and its related behavioral disorders remain unknown. The aim of the current resting-state functional magnetic resonance imaging (fMRI) study was to explore how the functional brain networks differed between CNP patients and age- and sex-matched healthy, pain-free controls (HCs). We also investigated whether these possible brain network changes in CNP patients were associated with fear avoidance belief (FAB) and the intensity of pain. We analyzed the resting-state fMRI data of 20 CNP patients and 20 HCs. FAB and the intensity of pain were assessed by Tampa Scale for Kinesiophobia (TSK) and Visual Analog Scale (VAS) of pain. The whole brain analysis showed that CNP patients had significant different functional connectivity (FC) compared with HCs, and the right dorsolateral prefrontal cortex (DLPFC) was a core hub of these altered functional networks. Furthermore, general linear model analyses showed that, in CNP patients, the increased FC between the right DLPFC and the right anterior insular cortex (aIC) significantly associated with increased TSK (p = 0.01, statistical significance after Bonferroni correction: p<0.025), and the FC between the right DLPFC and dorsal posterior cingulate cortex had a trend of inverse association with VAS (p = 0.04). Our findings suggest that aberrant FCs between the right DLPFC and aIC associated with CNP and its related FAB.

Altered functional connectivity associated with time discounting in chronic pain.

Chronic pain (CP) is a global problem extensively associated with an unhealthy lifestyle. Time discounting (TD), a tendency to assign less value to future gains than to present gains, is an indicator of the unhealthy behaviors. While, recent neuroimaging studies implied overlapping neuro mechanisms underlying CP and TD, little is known about the specific relationship between CP and TD in behavior or neuroscience. As such, we investigated the association of TD with behavioral measures in CP and resting-state brain functional network in both CP patients and healthy subjects. Behaviorally, TD showed a significant correlation with meaningfulness in healthy subjects, whereas TD in patients only correlated with pain intensity. We identified a specific network including medial and dorsolateral prefrontal cortex (PFC) in default mode network (DMN) associated with TD in healthy subjects that showed significant indirect mediation effect of meaningfulness on TD. In contrast, TD in patients was correlated with functional connectivity between dorsolateral PFC (DLPFC) and temporal lobe that mediated the effect of pain intensity on TD in patients. These results imply that TD is modulated by pain intensity in CP patients, and the brain function associated to TD is shifted from a medial to lateral representation within the frontal regions.

Breathing hydrogen sulfide prevents delayed paraplegia in mice.

Delayed paraplegia complicates the recovery from spinal cord ischemia or traumatic spinal cord injury. While delayed motor neuron apoptosis is implicated in the pathogenesis, no effective treatment or preventive measures is available for delayed paraplegia. Hydrogen sulfide exerts anti-apoptotic effects. Here, we examined effects of hydrogen sulfide breathing on the recovery from transient spinal cord ischemia. Breathing hydrogen sulfide starting 23 h after reperfusion for 5 h prevented delayed paraplegia after 5 min of spinal cord ischemia. Beneficial effects of hydrogen sulfide were mediated by upregulation of anti-apoptotic Bcl-XL and abolished by nitric oxide synthase 2 deficiency. S-nitrosylation of NFkB p65 subunit, which is induced by nitric oxide derived from nitric oxide synthase 2, facilitated subsequent sulfide-induced persulfidation of p65 and transcription of anti-apoptotic genes. These results uncover the molecular mechanism of the anti-apoptotic effects of sulfide based on the interaction between nitric oxide and sulfide. Exploitation of the anti-apoptotic effects of delayed hydrogen sulfide breathing may provide a new therapeutic approach for delayed paraplegia.

Interaction between anesthetic conditioning and ischemic preconditioning on metabolic function after hepatic ischemia-reperfusion in rabbits.

BACKGROUND: Both anesthetic-induced and ischemic preconditioning are protective against hepatic ischemia-reperfusion injury. However, the effects of these preventive methods on the metabolic function remain to be elucidated. We investigated the anesthetic conditioning and ischemic preconditioning on the metabolic function of the rabbit model of hepatic ischemia-reperfusion. METHODS: After approval by the institutional animal care and use committee, 36 Japanese White rabbits underwent partial hepatic ischemia for 90 min either under sevoflurane or propofol anesthesia. All the rabbits underwent 90 min of hepatic ischemia, and half of the rabbits in each group underwent additional 10-min ischemia and 10-min reperfusion before index ischemia. Hepatic microvascular blood flow was intermittently measured during reperfusion period, and galactose clearance, serum aminotransferase activities, and lactate concentrations were determined 180 min after reperfusion. RESULTS: Neither anesthetic conditioning with sevoflurane nor ischemic preconditioning altered hepatic microvascular blood flow during reperfusion and serum transaminase activities after reperfusion. However, galactose clearance of reperfused liver was significantly higher under sevoflurane anesthesia than propofol (0.016 ± 0.005/min vs. 0.011 ± 0.004/min). Statistically significant interaction between anesthetic choice and application of ischemic preconditioning suggests that the ischemic preconditioning is selectively protective under propofol anesthesia. Increase of blood lactate concentration was significantly suppressed under sevoflurane anesthesia compared to propofol (1.5 ± 0.8 vs. 3.9 ± 1.4 mmol/l) without any statistically significant interaction with the application of ischemic preconditioning. CONCLUSION: Sevoflurane attenuated the decrease of galactose clearance and increase of the blood lactate after reperfusion compared to propofol. Application of ischemic preconditioning was significantly protective under propofol anesthesia.

Anaphylactic Reactions to Native and Light-Exposed Sugammadex Suggested by Basophil Activation Test: A Report of 2 Cases.

We describe 2 patients who developed anaphylactic shock after sugammadex administration during anesthesia. Both had no history of prior sugammadex administration. The serum tryptase concentrations were elevated after the allergic reaction. Basophil activation testing 1 month after the events was positive for sugammadex in 1 patient, and negative in the other. However, it was positive for light-exposed sugammadex solution in both patients, suggesting a possible allergic reaction to a denatured compound of sugammadex generated by light exposure of the sugammadex solution.

Perioperative Factors Associated With Chronic Central Pain After the Resection of Intramedullary Spinal Cord Tumor.

OBJECTIVE: Some patients experience severe chronic pain after intramedullary spinal cord tumor (IMSCT) resection, but the underlying mechanisms have yet to be fully elucidated. We aimed to investigate perioperative factors associated with chronic pain after IMSCT resection. MATERIALS AND METHODS: We analyzed data from a postal survey and the medical records of patients who had undergone IMSCT resection in our institution between 2000 and 2008. Chronic pain was assessed using the Neuropathic Pain Symptom Inventory score, and its associations with factors related to tumor pathology, patient demographics, neurological findings, surgery, anesthesia, and perioperative management were determined. RESULTS: Seventy-eight consecutive patients (55 men and 23 women; age 17 to 79 y) were included in the statistical analysis of the present study. In univariate analyses, sex, body mass index, preoperative tumor-related pain, preoperative nonsteroidal anti-inflammatory drugs, intraoperative hypotension, postoperative corticosteroids, and decrease in Japanese Orthopaedic Association (JOA) scores were found to be associated with postsurgical chronic central pain. Logistic regression analysis identified 3 significant factors: a decline in JOA scores compared with preoperative values (odds ratio [OR], 3.33; 95% confidence interval [CI], 1.18-9.42; P=0.023), intraoperative hypotension (OR, 3.01; 95% CI, 1.02-8.97; P=0.047), and postoperative corticosteroids (OR, 3.21; 95% CI, 1.02-10.09; P=0.046). DISCUSSION: Decline in JOA score, intraoperative hypotension, and postoperative corticosteroids are independently associated with postsurgical chronic central pain. Intraoperative hypotension and the use of postoperative corticosteroids can be avoided or modified during perioperative management. As results from animal studies have indicated that the administration of corticosteroids may intensify chronic pain, further studies in larger cohorts are required to definitively determine the effect of corticosteroids on postsurgical central pain.

Fear-avoidance beliefs are independently associated with the prevalence of chronic pain in Japanese workers.

PURPOSE: Pain is a global public health problem with implications for both personal and social heath. Fear-avoidance beliefs (FABs) have been demonstrated to negatively impact and prolong pain in many Western countries, but little is known about the association between FABs and chronic pain (CP) in Asian countries, including Japan. We examined the relationship between FABs and CP in Japanese white-collar workers, a growing population with a high prevalence of CP. METHODS: Questionnaires and company records were used to gather data from 433 Japanese white-collar workers. Data were related to experience of pain, participant sociodemographic/health/lifestyle characteristics, fear-avoidance beliefs [Tampa Scale for Kinesiophobia (TSK)], work-related psychosocial factors (Brief Job Stress Questionnaire), and depressive illness [Psychological Distress Scale (K6)]. Analysis of covariance and multilevel logistic regression modeling were used to analyze associations between the data while controlling for factors known to influence CP prevalence. RESULTS: Prevalence rate of CP was 11.1% (48 of 433 persons). Adjusted odds ratios for participants with CP significantly increased in participants with high TSK scores, even after adjusting for factors known to influence CP prevalence. CONCLUSION: We found a significant association between high TSK scores and CP in Japanese white-collar workers when controlling for other known factors that influence CP such as work-related psychosocial characteristics and depressive conditions. This finding suggests that FABs are independently associated with prevalence of CP.

Desflurane anesthesia worsens emergence agitation in adult patients undergoing thyroid surgery compared to sevoflurane anesthesia.

BACKGROUND: The effect of volatile anesthetics on emergence agitation in adults remains unclear. We compared the degree of emergence agitation between desflurane and sevoflurane anesthesia in adults undergoing thyroid surgery. FINDINGS: One hundred and sixteen patients with American Society of Anesthesiologists status 1 or 2 were randomized into two groups: the desflurane group (group D) and the sevoflurane group (group S). After induction of anesthesia with fentanyl (1-2 µg/kg) and propofol (1.5-2.5 mg/kg), tracheal intubation was facilitated with suxamethonium (0.5-1.0 mg/kg). In group D, anesthesia was maintained with desflurane in 66% nitrous oxide and 33% oxygen supplemented with fentanyl when necessary; in group S, sevoflurane was used instead of desflurane. After the end of the surgery, emergence agitation was evaluated with a modified pediatric anesthesia emergence delirium scale (ranging from 0 to 16, with higher scores indicating more severe emergence agitation) before extubation. Time to extubation from the end of the surgery, postoperative pain (evaluated by a numerical rating scale [NRS]), and postoperative nausea and vomiting (PONV) after surgery were examined. The degree of emergence agitation was more severe in group D than in group S (median [interquartile range]: 5 [4-7] vs 4 [2-6], p = 0.008). Time to extubation, NRS scores, and PONV rates were similar between the two groups. CONCLUSIONS: Desflurane anesthesia worsened emergence agitation as compared with sevoflurane in adult patients undergoing thyroid surgery, but did not affect time to extubation, postoperative pain, or PONV. TRIAL REGISTRATION: UMIN000014215.

Deep anesthesia worsens outcome of rats with inflammatory responses.

OBJECTIVE: We tested the hypothesis that deep anesthesia with sevoflurane, known as a potent immunomodulator, for 4 h would worsen the 24-h outcomes of rats through modulation of the inflammatory responses. METHODS: Forty-nine male Wistar rats, administered low dose of lipopolysaccharide (0.5 mg/kg) intravenously to elicit moderate inflammatory responses mimicked mild surgical stress, underwent one minimum alveolar concentration (MAC) or 2 MAC sevoflurane anesthesia for 4 h. The 24-h survival rate, arterial blood gases, plasma interleukin (IL)-6 and tumor necrosis factor (TNF)-α concentrations, and rate of T lymphocyte apoptosis in spleen were evaluated. We further examined the effects of hypotension and TNF-α discharge on the survival rate. RESULTS: The survival rate in 2 MAC group was significantly lower accompanied with decreased base excess and increased level of cytokines (IL-6, TNF-α) compared to 1 MAC group. The apoptosis rate did not differ between the two groups. Neither norepinephrine infusion to restore hypotension nor administration of anti-TNF-α antibody improved the outcome in the 2 MAC group. CONCLUSIONS: Deep anesthesia with sevoflurane even for a short-term period augments the release of inflammatory cytokines evoked by inflammatory insults like surgical stress, impairs the acid-base balance, and subsequently deteriorates the outcomes.

Neutrophil gelatinase-associated lipocalin regulates gut microbiota of mice.

BACKGROUND AND AIM: Because neutrophil gelatinase-associated lipocalin (NGAL) is known to provide significant bacteriostatic effects during infectious conditions, we tested the hypothesis that this protein is up-regulated and secreted into the intraluminal cavity of the gut under critically ill conditions and is thus responsible for the regulation of bacterial overgrowth. METHODS: With our institutional approval, male C57BL/6J mouse (6-7 weeks) were enrolled and applied for lipopolysaccharide or peritonitis model compared with naïve control. We assessed NGAL protein concentrations in intestinal lumen and up-regulation of NGAL expression in intestinal tissues in in vivo as well as ex vivo settings. Simultaneously, we examined the effects of NGAL protein administration on the growth of Escherichia coli (E. coli) in in vivo and in vitro experimental settings. The localization of NGAL in intestinal tissues and lumen was also assessed by immunohistological approach using NGAL antibody. RESULTS: Both lipopolysaccharide and peritonitis insults evoked the marked up-regulation of NGAL mRNA and protein levels in gut tissues such as crypt cells. In addition, the administration of NGAL protein significantly inhibited the outgrowth of enteric E. coli under both in vitro and in vivo conditions, accompanied by histological evidence. CONCLUSION: Neutrophil gelatinase-associated lipocalin protein accompanied by apparent bacteriostatic action accumulated in the intestinal wall and streamed into the mucosal layer during critically ill state, thereby possibly shaping microbiota homeostasis in the gut.

Thiosulfate Mediates Cytoprotective Effects of Hydrogen Sulfide Against Neuronal Ischemia.

BACKGROUND: Hydrogen sulfide (H2S) exhibits protective effects in various disease models including cerebral ischemia-reperfusion (I/R) injury. Nonetheless, mechanisms and identity of molecules responsible for neuroprotective effects of H2S remain incompletely defined. In the current study, we observed that thiosulfate, an oxidation product of H2S, mediates protective effects of an H2S donor compound sodium sulfide (Na2S) against neuronal I/R injury. METHODS AND RESULTS: We observed that thiosulfate in cell culture medium is not only required but also sufficient to mediate cytoprotective effects of Na2S against oxygen glucose deprivation and reoxygenation of human neuroblastoma cell line (SH-SY5Y) and murine primary cortical neurons. Systemic administration of sodium thiosulfate (STS) improved survival and neurological function of mice subjected to global cerebral I/R injury. Beneficial effects of STS, as well as Na2S, were associated with marked increase of thiosulfate, but not H2S, in plasma and brain tissues. These results suggest that thiosulfate is a circulating "carrier" molecule of beneficial effects of H2S. Protective effects of thiosulfate were associated with inhibition of caspase-3 activity by persulfidation at Cys163 in caspase-3. We discovered that an SLC13 family protein, sodium sulfate cotransporter 2 (SLC13A4, NaS-2), facilitates transport of thiosulfate, but not sulfide, across the cell membrane, regulating intracellular concentrations and thus mediating cytoprotective effects of Na2S and STS. CONCLUSIONS: The protective effects of H2S are mediated by thiosulfate that is transported across cell membrane by NaS-2 and exerts antiapoptotic effects via persulfidation of caspase-3. Given the established safety track record, thiosulfate may be therapeutic against ischemic brain injury.