Exercise fatigue is a complex physiological and psychological phenomenon that includes peripheral fatigue in the muscles and central fatigue in the brain. Peripheral fatigue refers to the loss of force caused at the distal end of the neuromuscular junction, whereas central fatigue involves decreased motor output from the primary motor cortex, which is associated with modulations at anatomical sites proximal to nerves that innervate skeletal muscle. The central regulatory failure reflects a progressive decline in the central nervous system’s capacity to recruit motor units during sustained physical activity. Emerging evidence highlights the critical involvement of central neurochemical regulation in fatigue development, particularly through neurotransmitter-mediated modulation. Alterations in neurotransmitter release and receptor activity could influence excitatory and inhibitory signal pathways, thus modulating the perception of fatigue and exercise performance. Increased serotonin (5-HT) could increase perception of effort and lethargy, reduce motor drive to continue exercising, and contribute to exercise fatigue. Decreased dopamine (DA) and noradrenaline (NE) neurotransmission can negatively impact arousal, mood, motivation, and reward mechanisms and impair exercise performance. Furthermore, the serotonergic and dopaminergic systems interact with each other; a low 5-HT/DA ratio enhances motor motivation and improves performance, and a high 5-HT/DA ratio heightens fatigue perception and leads to decreased performance. The expression and activity of neurotransmitter receptors would be changed during prolonged exercise to fatigue, affecting the transmission of nerve signals. Prolonged high-intensity exercise causes excess 5-HT to overflow from the synaptic cleft to the axonal initial segment and activates the 5-HT1A receptor, thereby inhibiting the action potential of motor neurons and affecting the recruitment of motor units. During exercise to fatigue, the DA secretion is decreased, which blocks the binding of DA to D1 receptor in the caudate putamen and inhibits the activation of the direct pathway of the basal ganglia to suppress movement, meanwhile the binding of DA to D2 receptor is restrained in the caudate putamen, which activates the indirect pathway of the basal ganglia to influence motivation. Furthermore, other neurotransmitters and their receptors, such as adenosine (ADO), glutamic acid (Glu), and γ‑aminobutyric acid (GABA) also play important roles in regulating neurotransmitter balance and fatigue. The occurrence of central fatigue is not the result of the action of a single neurotransmitter system, but a comprehensive manifestation of the interaction between multiple neurotransmitters. This review explores the important role of neurotransmitters and their receptors in central motor fatigue, reveals the dynamic changes of different neurotransmitters such as 5-HT, DA, NE, and ADO during exercise, and summarizes the mechanisms by which these neurotransmitters and their receptors regulate fatigue perception and exercise performance through complex interactions. Besides, this study presents pharmacological evidence that drugs such as agonists, antagonists, and reuptake inhibitors could affect exercise performance by regulating the metabolic changes of neurotransmitters. Recently, emerging interventions such as dietary bioactive components intake and transcranial electrical stimulation may provide new ideas and strategies for the prevention and alleviation of exercise fatigue by regulating neurotransmitter levels and receptor activity. Overall, this work offers new theoretical insights into the understanding of exercise central fatigue, and future research should further investigate the relationship between neurotransmitters and their receptors and exercise fatigue.

Human exhaled breath has great application prospects,e.g.,monitoring pharmacokinetics,disease diagnosis,due to its advantages such as non-invasive and high-frequency sampling.Breath samples can be collected from the oral and nasal cavity.However,the oral and nasal environment affect the chemical composition of breath sample.Therefore,the investigation on the chemical composition of mouth-exhaled breath and nose-exhaled breath is crucial for selection of appropriate sampling strategy for individual studies.In this work,secondary electrospray ionization-high resolution mass spectrometry(SESI-HRMS)was applied to analysis of respiratory metabolomics in real time.A quantitative analysis approach was established for 9 kinds of volatile organic compounds(VOCs)e.g.2-butanone,2-pentanone,ethyl acetate,methyl methacrylate,toluene,styrene,mesitylene,isoprene and limonene.The limit of detection was 2.3?240.8 ng/m3.The intra-day(n=6)and inter-day(n=18)relative standard deviations were 0.6%?4.6%and 4.3%?12.2%,respectively.Nine healthy subjects were recruited to investigate the chemical composition of mouth-exhaled and nose-exhaled breath.The results showed the good performance in quantitative analysis of 9 VOCs in breath air.It was found that the number of unique component(m/z)detected in mouth-exhaled breath(167)was 2.2 times greater than that detected in nose-exhaled breath(76),which might result from the complex environment in oral cavity.The signal intensity of commun component(163)was significantly different between mouth-exhaled breath and nose-exhaled breath.Additionally,the elemental composition analysis showed that the proportion of polar compounds detected in nose-exhaled breath was higher than that in mouth-exhaled breath.This study demonstrated that there was significant differences in the chemical composition between mouth-exhaled and nose-exhaled breath,which provided a theoretical basis for selection of exhalation mode.

Objective To investigate the clinical application of perioperative human serum albumin(HSA)in cardiac surgery in multiple regions in China,and to evaluate the rationality of its clinical application in conjunction with the clinical guidelines,in order to provide a reference for promoting the rational application of HSA.Methods The medical records of patients who underwent cardiac surgery from April to June 2019 in eight hospitals across the country were retrospectively collected.The statistical information on patients'general information,the dosage,course of treatment,and cost of HSA,and the serum albumin level before and after medication was analyzed to evaluate the use of HSA.Relevant evaluation criteria were established,and the rationality of its medication was evaluated.Results Data from a total of 449 patients were included for analysis,the appropriate rate of medication was 81.1％.The course of medication was mostly＞2-5 days and the total amount of HSA was mostly 50-99 g.The main purpose of medicaiton were improving colloid osmotic pressure,reducing exudation to improve interstitial edema,postoperative volume expansion.Conclusion Clinical attention should be paid to ensure the rational application of HSA in cardiac surgery during the perioperative period and prevent the abuse of blood products.

Objective:To investigate the effects of human umbilical cord mesenchymal stem cell (hUCMSC) exosomes in the treatment of full-thickness skin defect wounds in mice through local wound application, subcutaneous injection at the wound margin, and tail vein injection, and to explore the optimal administration route of hUCMSC exosomes for wound treatment.Methods:This study was an experimental study. hUCMSC exosomes were extracted from the discarded umbilical cord tissue of three normal delivery women aged 25-35 years in the Department of Obstetrics and Gynecology of Baogang Hospital of Inner Mongolia and successfully identified. Totally 120 male BALB/c mice aged 6-8 weeks were selected, and full-thickness skin defect wounds were prepared on the back of them. According to the random number table, the injured mice were divided into control group (without drug administration), local wound application group, wound margin subcutaneous injection group, and tail vein injection group (with 30 mice in each group). Mice in the latter three groups were given 0.2 mL phosphate buffer solution containing 200 μg hUCMSC exosomes by local wound application, subcutaneous injection at the wound margin, and tail vein injection, respectively. On post injury day (PID) 7, 14, and 21, the general condition of the wound was observed, and the wound healing rate was calculated; the wound tissue was collected, the pathological changes and collagen fibers were observed respectively by hematoxylin-eosin staining and Masson staining, the number of new microvessels was observed by CD31 immunohistochemical staining, and the content of tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) was detected by enzyme-linked immunosorbent assay. The sample number was 10 in each group at each time point.Results:On PID 7, 14, and 21, the wounds of mice in the 4 groups all healed gradually, and the wound healing of the mice in wound margin subcutaneous injection group was the best; the wound healing rates of mice in the three administration groups were significantly higher than those in control group ( P<0.05), the wound healing rates of mice in wound margin subcutaneous injection group and tail vein injection group were significantly higher than those in local wound application group ( P<0.05), and the wound healing rates of mice in wound margin subcutaneous injection group were significantly higher than those in tail vein injection group ( P<0.05). On PID 7, 14, and 21, the growth and epithelialization speed of the wound tissue of mice in the three administration groups were significantly accelerated, and the collagen fibers in the wounds of mice in the three administration groups were larger in number and more neatly arranged in comparison with the control group. On PID 7, 14, and 21, under every 200-fold visual field, the number of new microvessels in the wound tissue of mice in local wound application group was 24.1±2.5, 50.7±4.1, and 44.2±2.3, respectively, the number of new microvessels in the wound tissue of mice in wound margin subcutaneous injection group was 32.2±2.9, 67.5±4.9, and 53.6±3.7, respectively, and the number of new microvessels in the wound tissue of mice in tail vein injection group was 27.8±2.4, 59.1±3.7, and 49.6±2.6, respectively, which was significantly more than 20.6±1.7, 46.7±3.4, and 40.9±2.8 in control group ( P<0.05); the number of new microvessels in the wound tissue of mice in wound margin subcutaneous injection group and tail vein injection group was significantly more than that in local wound application group ( P<0.05); the number of new microvessels in the wound tissue of mice in wound margin subcutaneous injection group was significantly more than that in tail vein injection group ( P<0.05). On PID 7, 14, and 21, the content of TNF-α and IL-6 in the wound tissue of mice in the three administration groups was significantly less than that in control group ( P<0.05), the content of TNF-α and IL-6 in the wound tissue of mice in wound margin subcutaneous injection group and tail vein injection group was significantly less than that in local wound application group ( P<0.05), and the content of TNF-α and IL-6 in the wound tissue of mice in wound margin subcutaneous injection group was significantly less than that in tail vein injection group ( P<0.05). Conclusions:Local wound application, subcutaneous injection at the wound margin, and tail vein injection of hUCMSC exosomes can all promote the wound healing of full-thickness skin defects in mice through alleviating excessive inflammatory response and promoting angiogenesis. Among them, subcutaneous injection at the wound margin has a better therapeutic effect, indicating subcutaneous injection at the wound margin is the optimal administration route for hUCMSC exosomes in wound treatment.

Objective:To explore the diagnostic value of thromboelastography (TEG) combined with conventional coagulation test (CCT) for trauma-induced coagulopathy (TIC) in patients with electric burns in the early stage.Methods:This study was a retrospective case series research. From February 2018 to February 2024, the clinical data of 128 electric burn patients and 118 thermal burn patients who met the inclusion criteria and admitted to the Department of Burn Surgery of the Third Affiliated Hospital of Inner Mongolia Medical University were collected, including 224 males and 22 females, aged (38±14) years. The patients were divided into electric burn group (128 cases) and thermal burn group (118 cases) according to their injuries. The incidence of TIC, the indicators of CCT, including prothrombin time, activated partial thromboplastin time, thrombin time, fibrinogen level, D-dimer level, platelet count, and the detection indicators of TEG, including coagulation reaction time, K value, coagulation angle, maximum thrombus amplitude, comprehensive coagulation index, and lysis rate at 30 minutes after maximum amplitude within 8 hours of admission were compared between the two groups of patients. The Kappa test was used to analyze the consistency between CCT and TEG in diagnosing TIC in patients with electric burns in the early stage after burns. The receiver operating characteristic curves of CCT, TEG, and TEG combined with CCT in diagnosing TIC in 128 patients with electric burns were drawn, and the area under the curve (AUC), the maximum Jordan index, and sensitivity and specificity at this time were calculated.Results:The proportion of patients diagnosed with TIC in electric burn group was 19.5% (25/128) within 8 hours of admission, which was significantly higher than 10.2% (12/118) in thermal burn group ( χ2=4.21, P<0.05). Compared with those in thermal burn group, prothrombin time was significantly shortened ( t=-2.32, P<0.05), D-dimer level, fibrinogen level, and platelet count were significantly increased (with Z values of -2.11 and -4.16, respectively, t=4.69, P<0.05), the coagulation reaction time was significantly shortened ( t=-2.51, P<0.05), and the maximum thrombus amplitude and lysis rate at 30 minutes after the maximum amplitude were significantly increased (with t values of 2.50 and 2.10, respectively, P<0.05) in patients in electric burn group within 8 hours of admission. There were no statistically significant differences in the other CCT indicators and TEG detection indicators between the two groups of patients ( P>0.05). The CCT and TEG showed high consistency in the diagnosis of TIC in patients with electric burns in the early stage after burns (Kappa=0.63, P<0.05). The AUCs of TEG combined with CCT, TEG, and CCT in diagnosis of TIC in 128 patients with electric burns were 0.92, 0.84, and 0.77 (with 95% confidence intervals of 0.86-0.97, 0.71-0.97, and 0.71-0.97, respectively), with the maximum Jordan indexes of 0.86, 0.57, and 0.65. At this time, the specificity was 93.7%, 83.2%, and 88.2%, respectively, and the sensitivity was 92.3%, 87.5%, and 76.5%, respectively. Conclusions:Patients with electric burns are in a state of hypercoagulability of coagulation system and hyperfunction of fibrinolysis system in the early stage after burns, and TEG combined with CCT can increase the diagnostic rate of TIC in patients with electric burns.

Background/Aims: Despite the high efficacy of direct-acting antivirals (DAAs), approximately 1–3% of hepatitis C virus (HCV) patients fail to achieve a sustained virological response. We conducted a nationwide study to investigate risk factors associated with DAA treatment failure. Machine-learning algorithms have been applied to discriminate subjects who may fail to respond to DAA therapy. Methods: We analyzed the Taiwan HCV Registry Program database to explore predictors of DAA failure in HCV patients. Fifty-five host and virological features were assessed using multivariate logistic regression, decision tree, random forest, eXtreme Gradient Boosting (XGBoost), and artificial neural network. The primary outcome was undetectable HCV RNA at 12 weeks after the end of treatment. Results: The training (n=23,955) and validation (n=10,346) datasets had similar baseline demographics, with an overall DAA failure rate of 1.6% (n=538). Multivariate logistic regression analysis revealed that liver cirrhosis, hepatocellular carcinoma, poor DAA adherence, and higher hemoglobin A1c were significantly associated with virological failure. XGBoost outperformed the other algorithms and logistic regression models, with an area under the receiver operating characteristic curve of 1.000 in the training dataset and 0.803 in the validation dataset. The top five predictors of treatment failure were HCV RNA, body mass index, α-fetoprotein, platelets, and FIB-4 index. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of the XGBoost model (cutoff value=0.5) were 99.5%, 69.7%, 99.9%, 97.4%, and 99.5%, respectively, for the entire dataset. Conclusions Machine learning algorithms effectively provide risk stratification for DAA failure and additional information on the factors associated with DAA failure.

Purpose: This study was conducted to evaluate the efficacy of bladder outlet surgery in patients with detrusor underactivity (DU) and to identify factors associated with successful outcomes. Methods: We conducted a retrospective review of men diagnosed with DU in urodynamic studies who underwent bladder outlet surgery for lower urinary tract symptoms between May 2018 and April 2023. The International Prostate Symptom Score (IPSS) questionnaire, uroflowmetry (UFM), and multichannel urodynamic studies were administered. Successful treatment outcomes were defined as either an IPSS improvement of at least 50% or the regaining of spontaneous voiding in patients urethral catheterization prior to surgery. Results: The study included 93 male patients. Men diagnosed with significant or equivocal bladder outlet obstruction (BOO) experienced significant postoperative improvements in IPSS (from 20.6 to 6.0 and from 17.4 to 6.5, respectively), maximum urine flow rate (from 5.0 mL/sec to 14.4 mL/sec and from 8.8 mL/sec to 12.2 mL/sec, respectively) and voiding efficiency (from 48.8% to 86.0% and from 61.2% to 85.1%, respectively). However, in the group without obstruction, the improvements in IPSS and UFM results were not significant. The presence of detrusor overactivity (odds ratio [OR], 3.152; P=0.025) and preoperative urinary catheterization (OR, 2.756; P=0.040) were associated with favorable treatment outcomes. Conversely, an unobstructed bladder outlet was identified as a negative prognostic factor. Conclusions In men with DU accompanied by equivocal or significant BOO, surgical intervention to alleviate the obstruction may enhance the IPSS, quality of life, and UFM results. However, those with DU and an unobstructed bladder outlet face a comparatively high risk of treatment failure. Preoperative detrusor overactivity and urinary catheterization are associated with more favorable surgical outcomes. Consequently, active deobstructive surgery should be considered for patients with DU who are experiencing urinary retention.