A robust yeast biocontainment system with two-layered regulation switch dependent on unnatural amino acid.

Synthetic auxotrophy in which cell viability depends on the presence of an unnatural amino acid (unAA) provides a powerful strategy to restrict unwanted propagation of genetically modified organisms (GMOs) in open environments and potentially prevent industrial espionage. Here, we describe a generic approach for robust biocontainment of budding yeast dependent on unAA. By understanding escape mechanisms, we specifically optimize our strategies by introducing designed "immunity" to the generation of amber-suppressor tRNAs and developing the transcriptional- and translational-based biocontainment switch. We further develop a fitness-oriented screening method to easily obtain multiplex safeguard strains that exhibit robust growth and undetectable escape frequency (<~10-9) on solid media for 14 days. Finally, we show that employing our multiplex safeguard system could restrict the proliferation of strains of interest in a real fermentation scenario, highlighting the great potential of our yeast biocontainment strategy to protect the industrial proprietary strains.

The Mediating Role of Self-Perceived Burden Between Social Support and Fear of Progression in Renal Transplant Recipients: A Multicenter Cross-Sectional Study.

Purpose: To explore the mechanism of social support and fear of progression (FoP) in renal transplant recipients (RTRs) and the self-perceived burden that acts as a mediator between social support and FoP. Patients and Methods: Sociodemographic and clinical characteristics, the Social Support Rating Scale (SSRS), the Self-Perceived Burden Scale (SPBS), and the Fear of Progression-Questionnaire-Short Form (FoP-Q-SF) were used. Structural equation modeling (SEM) was used to examine the mediating role of self-perceived burden. Results: Our results showed that social support was negatively related to the self-perceived burden (r = -0.28, p < 0.001) and FoP (r = -0.37, p < 0.001). Moreover, we determined that self-perceived burden was positively related to FoP (r = 0.58, p < 0.001) and that the indirect effect of social support on FoP via self-perceived burden was significant (ß = -0.172, 95% CI: -0.253, -0.097), and with a mediating effect value of 36.9%. Conclusion: The FoP in RTRs is a concern. Higher social support and lower self-perceived burden can reduce the risk of FoP. Healthcare professionals (HCPs) should assist RTRs in correctly evaluating an individual's social support system, helping them optimize social support to reduce the self-perceived burden and the development of FoP.

The mediating effect of sense of coherence on the caregiver ability-caregiver burden relationship for caregivers of children with liver transplantation in China.

BACKGROUND: Caregivers of children who have had liver transplantation often experience chronic care stress. Previous studies have focused on caregivers' negative feelings (e.g., caregiver burden), but few studies have focused on caregivers' positive feelings (e.g., sense of coherence) and caregiver ability. OBJECTIVES: The study purpose was to investigate the status of the burden of caregivers of children with liver transplantation, and to explore the mediating role of sense of coherence between caregiver ability and caregiver burden. METHODS: There were 461 questionnaires collected from a tertiary-level hospital from caregivers of children who had liver transplantation from April to June 2022. Demographic data, Family Caregiver Task Inventory, Sense of Coherence Scale-13, and Zarit Burden Interview were used. The STROBE checklist was monitored. RESULTS: The average caregiver burden score was 32.19 ± 16.71. The distribution of caregiver burden levels was mild (42.52%), none (26.25%), moderate (24.95%), and severe (6.29%). Caregiver ability score was negatively correlated with caregiver burden score; however, sense of coherence score was negatively correlated with caregiver burden score. Caregiver ability partially mediated caregiver burden through sense of coherence (38.51%). CONCLUSION: The caregiver burden level was not heavy in general. Both positive and negative feelings were present in caregivers. Caregiver ability also reduced the caregiver burden through sense of coherence.

Effect of short-term air pollution exposure on migraine: A protocol for systematic review and meta-analysis on human observational studies.

BACKGROUND: The World Health Organization (WHO) has identified air pollution as one of the greatest environmental risks to public health. High levels of ambient air pollution are known to have adverse health effects, but the relationship between exposure to air pollutants and migraine attack has not been established. OBJECTIVES: This study aims to systematically review the effects of short-term exposure to fine and coarse particulate matter (PM), ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide on migraine attack. METHODS: The systematic review and meta-analysis will follow the WHO handbook for guideline development. Our protocol will comply with the guidelines of the Preferred Reporting Items for Systematic Review and meta-Analysis Protocols. ELIGIBILITY CRITERIA: Original peer-reviewed studies conducted in the general population regardless of age and sex to investigate the association between short-term exposure to ambient air pollutants and migraine will be eligible for inclusion. Only time-series, case-crossover, and panel studies will be included. INFORMATION SOURCES: We will search the electronic databases MEDLINE, Embase, Web of Science, Global Health, Cumulative Index to Nursing and Allied Health Literature in accordance with the pre-established search strategy. We will also check the reference list of included papers and previous reviews for supplementary search. DATA SYNTHESIS METHOD: We will perform data extraction in accordance with the predesigned table. Using random-effects meta-analysis, we will present summary statistics (RRs and corresponding 95% CIs) associated with standardized increases in each pollutant level. Heterogeneity between studies will be assessed using 80% prediction intervals (PI). Subgroup analyzes will be performed to explore sources of heterogeneity, if any. The main findings will be presented in summary of finding table, visual display and narrative synthesis. We will review the impact of each air pollutant exposure separately. EVIDENCE APPRAISAL: We will employ the adaption of Grading of Recommendations, Assessment, Development, and Evaluations tool to assess the confidence in the body of evidence.

Social support mediates the relationship between illness perception and psychosocial adaptation among young and middle-aged kidney transplant recipients in China.

Background: No research has yet been done on social support's influence on the association between illness perception and psychosocial adaptation among young and middle-aged kidney transplant recipients in China. Accordingly, it remains unclear how medical personnel can assist patients in successfully adjusting to the early postoperative period and improving their health. Objective: This study sought to explore the influence of illness perception and social support on the psychosocial adaptation of young and middle-aged recipients of kidney transplants in China during the early postoperative period. Methods: This study adopted a cross-sectional design. The study included 236 young and middle-aged kidney transplant recipients from a tertiary hospital in China. Demographic and disease-related data were collected. Additionally, the Psychosocial Adjustment to Illness Scale-Self-Report, the Brief Illness Perception Questionnaire, and the Multidimensional Scale of Perceived Social Support were used to assess participants' psychosocial adaptation, illness perception, and social support, respectively. The model was examined using descriptive analysis, Pearson's correlation analysis, hierarchical multiple regression analysis, and the PROCESS Macro in SPSS 26.0. Results: A total of 176 (74.56%) participants reported an average psychosocial adaptation score >50, which is relatively negative. Marital status, education level, residence, per capita monthly income (in Chinese yuan), medical insurance, work status, post-transplant time, body mass index, creatinine status, and complications were all related to psychosocial adaptation (p < 0.05). The more negative their illness perception and the worse their social support, the worse the psychosocial adaptation of young and middle-aged kidney transplant recipients. Further, the effect of illness perception on psychosocial adaptation was partially mediated by social support (36.56%). Conclusion: In general, the psychosocial adaption level of young and middle-aged kidney transplant recipients was negative during the early postoperative period. Healthcare teams should assist patients in building a positive illness perception shortly following kidney transplantation, while also providing psychological care and support to help them cope with the onset of psychosocial issues.

Mediating effects of psychological capital on the relationship between workplace violence and professional identity among nurses working in Chinese public psychiatric hospitals: a cross-sectional study.

OBJECTIVE: To examine the relationship between workplace violence (WPV) and professional identity among Chinese psychiatric nurses and the mediating effects of psychological capital (PsyCap) from this association. SETTING: Seven public tertiary psychiatric hospitals in Liaoning Province, China. PARTICIPANTS: A total of 952 psychiatric nurses were recruited for this study. Registered nurses who have been engaged in psychiatric nursing for more than 1 year were eligible as participants in this investigation. OUTCOME MEASURES: Questionnaires consisting of the Workplace Violence Scale, the Occupational Identity Scale, the Psychological Capital Questionnaire and a demographic data sheet were used to collect participant information. We used hierarchical multiple regression and asymptotic and resampling strategies to examine the mediating role of PsyCap in the relationship between WPV and professional identity. RESULTS: WPV was negatively associated with professional identity after controlling for demographic factors (ß=-0.353; p<0.001). PsyCap mediated the relationship between WPV and professional identity, according to the mediation analysis (a×b=-0.150, bias-corrected and accelerated 95% CI (BCa 95% CI) (-0.185 to -0.115); p<0.001). In addition, two dimensions of PsyCap: hope (a×b=-0.075, BCa 95% CI (-0.104 to -0.049); p<0.001) and resilience (a×b=-0.064, BCa 95% CI (-0.090 to -0.039); p<0.001) mediated the association between WPV and professional identity. For professional identity, hope, resilience and PsyCap mediation accounted for 21.6%, 18.1% and 42.4%, respectively. CONCLUSIONS: Based on these findings, PsyCap could partially mediate the relationship between WPV and professional identity. Therefore, hospital administrators should implement measures to prevent and reduce WPV and provide nurses with skills training programmes to improve the PsyCap such as hope and resilience.

Factors influencing employment rates and states after liver transplantation in China: A multi-centre cross-sectional study.

AIM: The aim of this study was to assess employment rates and states and the factors influencing liver transplant recipients in China. DESIGN: A cross-sectional study. METHODS: A total of 212 liver transplant recipients were included in this study. Questionnaires for general situation information and the Hospital Anxiety and Depression Scale, Perceived Social Support Scale and Chronic Disease Self-Efficacy Scale were used. RESULTS: Among the liver transplantation, 212 recipients were included in the study, 125 (59%) were employed after liver transplantation compared with 148 (69.8%) who were employed before liver transplantation. Among the 125 recipients that returned to work, only 38.2% thought their employment states were good before liver transplantation, while 81.6% thought that their employment states were good after liver transplantation. Gender, age and employment status before transplantation, aetiology of liver disease, number of physical activities, per capita monthly income, comorbidity and depression were significantly associated with return to work. Self-efficacy, social support, liver function and nature of work were significantly associated with employment state.

Epidemiology of Musculoskeletal Injuries in the Navy: A Systematic Review.

Objectives: This study aimed to critically review the results of recent studies that investigated the epidemiology of noncombat-related musculoskeletal injuries (MSIs) in the Navy. Methods: A systematic search was conducted of three major databases (Pubmed, Embase, and Cochrane) to identify epidemiological studies on MSIs in the Navy. Study selection and risk of bias assessment were conducted. Results: The overall prevalence of MSIs ranged from 12.69% to 48.81%. And the prevalence of head and face injuries, upper extremity injuries, spine injuries, chest injuries, and lower extremity injuries were 0.11%-0.66%, 0.53%-11.47%, 0.75%-12.09%, 0.43%-0.95%, and 0.4%-21.17%, respectively. For the specific MSIs, the incidence ranged from 0.03/1000 person-years to 32.3/1000 person-years in the Navy and Marines. The ankle-foot, lumbopelvic, knee and lower leg, and shoulder were identified as the most frequent location for MSIs. Conclusion: This systematic review summarized that the Navy population had a high prevalence of MSIs. And different risk factors for MSIs varied from different anatomic locations. This systematic review also provided valuable information on MSIs for sports medicine specialists.

Non-invasive brain neuromodulation techniques for chronic low back pain.

Structural and functional changes of the brain occur in many chronic pain conditions, including chronic low back pain (CLBP), and these brain abnormalities can be reversed by effective treatment. Research on the clinical applications of non-invasive brain neuromodulation (NIBS) techniques for chronic pain is increasing. Unfortunately, little is known about the effectiveness of NIBS on CLBP, which limits its application in clinical pain management. Therefore, we summarized the effectiveness and limitations of NIBS techniques on CLBP management and described the effects and mechanisms of NIBS approaches on CLBP in this review. Overall, NIBS may be effective for the treatment of CLBP. And the analgesic mechanisms of NIBS for CLBP may involve the regulation of pain signal pathway, synaptic plasticity, neuroprotective effect, neuroinflammation modulation, and variations in cerebral blood flow and metabolism. Current NIBS studies for CLBP have limitations, such as small sample size, relative low quality of evidence, and lack of mechanistic studies. Further studies on the effect of NIBS are needed, especially randomized controlled trials with high quality and large sample size.

Effect of exercise intervention on social distance in middle-aged and elderly patients with chronic low back pain.

Background: Increased social distance is one of the manifestations of social impairment. Chronic low back pain (CLBP) is one of factors associated with increased social distance and social withdrawal. Exercise therapy is an effective means to social impairment. However, whether exercise could reduce social distance in patients with CLBP remains unknown. This study aimed to investigate the effect of exercise on social distance in middle-aged and elderly patients with CLBP. Methods: The longitudinal intervention recruited 29 middle-aged and elderly patients with CLBP from various communities in Yangpu District, Shanghai, China. The participants received exercise intervention for 8 weeks. The assessments were conducted before and after the intervention, including social distance, pain intensity, unpleasantness of pain, Roland-Morris Questionnaire (RMDQ), Self-Rating Anxiety Scale (SAS), and Self-Rating Depression Scale (SDS). Intention to treat analysis was performed. Results: After the 8-week exercise intervention, the social distance of patients with CLBP was shorter than that before intervention and showed significant difference (p < 0.05). The scores of pain intensity, unpleasantness of pain, RMDQ, SAS, and SDS also decreased and were significantly different between pre- and post-intervention (p < 0.05). In addition, the social distance, pain intensity, unpleasantness of pain, RMDQ, SAS, and SDS scores of the moderate CLBP group decreased more after the intervention compared with those of the mild CLBP group. Conclusion: The 8-week exercise intervention cannot only shorten the social distance in middle-aged and elderly patients with CLBP but also relieve pain, disability, and negative emotions.

Efficient biodegradation of di-(2-ethylhexyl) phthalate by a novel strain Nocardia asteroides LMB-7 isolated from electronic waste soil.

The di-2-ethylhexyl phthalate (DEHP) degrading strain LMB-7 was isolated from electronic waste soil. According to its biophysical/biochemical characteristics and 16S rRNA gene analysis, the strain was identified as Nocardia asteroides. Optimal pH and temperature for DEHP degradation were 8.0 and 30 °C, respectively, and DEHP removal reached 97.11% after cultivation for 24 h at an initial concentration of 400 mg/L. As degradation intermediates, di-butyl phthalates, mono-2-ethylhexyl phthalate and 2-ethylhexanol could be identified, and it could be confirmed that DEHP was completely degraded by strain LMB-7. To our knowledge, this is a new report of DEHP degradation by a strain of Nocardia asteroides, at rates higher than those reported to date. This finding provides a new way for DEHP elimination from environment.

Global Trends and Research Hotspots of Exercise for Intervening Diabetes: A Bibliometric Analysis.

Background: Diabetes is a chronic metabolic disease characterized by hyperglycemia that often occurs in adults. Many studies have indicated that exercise is beneficial to the medical management of diabetes. Bibliometric analysis can help investigators to identify the current research concerns to guide future research directions. Nevertheless, the overview bibliometric analysis of this global research topic related to exercise and diabetes is lacking. The present bibliometric study aimed to investigate development trends and research hotspots of exercise and diabetes research and provide researchers with new perspectives in further studies. Materials and Methods: The articles and reviews regarding exercise and diabetes between 2000 and 2020 were retrieved from the Web of Science Core Collection. The scientometrics analytical tool CiteSpace software was used to analyze the cooperation among countries/institutions/journals/authors, analysis of co-occurrence keywords, keywords bursts, and references. Results: In all, 3,029 peer-reviewed papers were found with a persistently increased tendency over time. The most prolific country and institution were the USA (965) and Univ Alberta (76), respectively. Diabetes Care published most papers (178) and was the most co-cited journal (2,630). Riddell MC had the most publications (53), and Sigal RJ was the most influential author (503 cited times). Colberg et al.'s paper (co-citation counts: 183) showed the strongest citation bursts by the end of 2020, which was the most representative reference. The four research focuses were mellitus, exercise, physical activity, and glycemic control. The two frontiers trends were sedentary behavior and stress. The combination of aerobic and resistance training can effectively improve glycemic control, decrease HbA1c levels, enhance cardiorespiratory fitness, improve lipid levels, and decrease the demand for non-insulin antihyperglycemic agents. Conclusions: This study offers a scientific perspective on exercise and diabetes research and provides investigators with valuable information to detect the current research condition, hotspots, and emerging trends for further study.

ROS-sensitive calcipotriol nano-micelles prepared by methoxypolyethylene glycol (mPEG) - modified polymer for the treatment of psoriasis.

Oxidative stress due to excessive reactive oxygen species (ROS) production in the skin microenvironment is one of the main mechanisms in psoriasis pathogenesis. A nano drug delivery system based on ROS-responsive release can enhance drug release at the target site. In this study, a ROS-sensitive material methoxypolyethylene glycol-thioether-thiol (mPEG-SS) was synthesized using mPEG as the parent structure with sulfide structural modification. An mPEG-SS-calcipotriol (mPEG-SS-CPT, PSC) nano-micelle percutaneous delivery system was prepared by encapsulating CPT. A small animal imaging system was used to study PSC's the ROS-sensitive drug release process. It is shown that endogenous ROS mainly affects PSC and releases drugs. Finally, the therapeutic effect of PSC on psoriasis was explored by animal experiments. Ultimately, it ameliorates imiquimod-induced psoriasis-like inflammation. Overall, PSC is an effective ROS-sensitive transdermal drug delivery system that is expected to provide a new strategy for treating psoriasis.

Bibliometric Study of Exercise and Tendinopathy Research from 2001 to 2020.

BACKGROUND Tendinopathy is a tendon disease that often occurs in athletes. Many studies have revealed that exercise therapy is beneficial for the nonoperative management of tendinopathy. However, the general aspect bibliometric analysis of this global research topic associated with exercise and tendinopathy is lacking. The present study aimed to make a bibliometric analysis of worldwide development tendency and research hotspots in exercise and tendinopathy research from 2001 to 2020. MATERIAL AND METHODS Using the Web of Science, articles and reviews published between 2001 and 2020 were retrieved from the Science Citation Index Expanded database. CiteSpace was used to analyze the relationship among publications, countries, institutions, journals, authors, references, and keywords. RESULTS In total, 857 articles were found in this study. Over the past 20 years, there was a marked increase in the number of publications. A total of 194 different scholarly journals were dedicated to the categories Sport Sciences, Orthopedics, and Rehabilitation. The USA and La Trobe University were the most prolific country and institution, respectively. The British Journal of Sports Medicine was the prominent journal for research on exercise and tendinopathy and had the most publications. The analysis of keywords showed that rehabilitation, rotator cuff tendinopathy, stiffness, and disability of individuals with tendinopathy had become the research focus in this field. CONCLUSIONS Bibliometric analysis provides a historical and scientific perspective on exercise and tendinopathy research, providing relevant researchers, funding agencies, and policymakers with valuable information to explore the current research status, hotspots, and new directions for future research.

The translation and validation of the Organ Transplant Symptom and Well-Being Instrument in China.

To translate the Organ Transplant Symptom and Well-Being instrument (OTSWI) into Chinese and test the reliability and validity of the Chinese version. A total of 259 patients with organ transplants were recruited from The First Affiliated Hospital of China Medical University in Shenyang, from November 2020 to January 2021. Construct validity was evaluated using exploratory factor analysis (EFA) and reliability were assessed using test-retest reliability and internal consistency. The Cronbach's α of the Chinese version of the Organ Transplant Symptom and Well-being instrument was 0.93. EFA demonstrated that 80.785% of the total variance was explained by a seven-factor solution. The criterion validity of the SF-36 was -0.460 (p < .01), while the test-retest reliability was 0.710. The Chinese version of the OTSWI questionnaire is a valid and reliable instrument for assessing the quality of life of organ transplant patients for symptoms and well-being in China.

Effects of Self-Myofascial Release Using a Foam Roller on the Stiffness of the Gastrocnemius-Achilles Tendon Complex and Ankle Dorsiflexion Range of Motion.

Increased muscle stiffness can contribute to reduced range of motion (ROM) and impaired function. Reduced ankle dorsiflexion ROM has been associated with increased injury risk in the ankle. Self-myofascial release (SMR) has been widely used in clinical and sports settings, but the effects of SMR on gastrocnemius and Achilles tendon (AT) stiffness are unclear. Therefore, we investigated the effects of self-myofascial release using a foam roller (FR) on the stiffness of the gastrocnemius-AT complex and ankle dorsiflexion ROM. Fifty healthy, untrained, and non-sedentary participants (age=22.5±2.6years) were randomly divided into an intervention group (FR group) and a control group. The subjects in the intervention group received a single foam roller intervention (three sets of 1min), while the subjects in the control group performed a 5-min sedentary rest. Stiffness of the gastrocnemius-AT complex was evaluated using MyotonPRO and the ankle dorsiflexion ROM was assessed using the weight-bearing lunge test. For the foam roller and control groups, the between-group analysis revealed a statistically significant difference in gastrocnemius stiffness and ankle dorsiflexion ROM after intervention (p<0.05). Within-group analysis revealed a significant increase in ROM and a significant decrease in medial and lateral gastrocnemius (LG) stiffness for the foam roller group after the intervention (p<0.05). In addition, further analysis of the preintervention data revealed a significant negative correlation between ankle dorsiflexion ROM and AT stiffness (r=-0.378 and p=0.007). These results suggest that self-myofascial release using a foam roller on the calf is an effective method for decreasing the stiffness of the gastrocnemius and increasing ankle dorsiflexion ROM.

Modulation in the Stiffness of Specific Muscles of the Quadriceps in Patients With Knee Osteoarthritis and Their Relationship With Functional Ability.

Deficits in the flexibility of the quadriceps are one of the risk factors for developing knee joint disorders. No studies have investigated the changes in the stiffness of the quadriceps muscle among patients with knee osteoarthritis (OA). Therefore, the purpose of this study was to investigate changes in the stiffness of specific-muscle of the quadriceps in patients with knee OA and their relationship with functional ability. Twenty-five patients with knee OA and 25 healthy, asymptomatic subjects were recruited in this study. The stiffness of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) in all participants was evaluated using MyotonPRO at 60° and 90° flexion of the knee joint. The results of this study showed a greater VL stiffness in patients with knee OA than in healthy subjects at both 60° and 90° of knee flexion (p < 0.05). Significant differences in VL, VM and RF stiffness were obtained at different knee joint angles in individuals with and without knee OA (p < 0.05). In addition, there was a positive correlation between VL stiffness and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores in patients with Knee OA (60° of knee flexion: r = 0.508, p = 0.010; 90° of knee flexion: r = 0.456, p = 0.022). These results indicate that there is an increase in VL stiffness in patients with knee OA compared with healthy, asymptomatic subjects, and the quadriceps stiffness was increased with knee flexion in both healthy subjects and patients with knee OA. VL stiffness is associated with WOMAC scores in patients with knee OA.

Stiffness of the Gastrocnemius-Achilles Tendon Complex Between Amateur Basketball Players and the Non-athletic General Population.

Muscle and tendon stiffness are related to sports performance, tendinopathy, and tendon degeneration. However, the effects of habitual loading on muscle and tendon mechanical properties are unclear. Using amateur basketball players as examples, we investigated the effects of mechanical loading on the stiffness of the gastrocnemius-Achilles tendon (AT) complex in non-dominant and dominant lower limbs. Then, we evaluated the correlation between gastrocnemius and AT stiffness. Forty participants (20 amateur basketball players; 20 normal non-athletic persons) were recruited for this study. Stiffness of the gastrocnemius-AT complex was assessed using MyotonPRO at neutral position and 10° dorsiflexion of the ankle joint in participants from amateur basketball players and the non-athletic general population. Our results showed a greater stiffness of the gastrocnemius-AT complex in amateur basketball players than that in healthy non-athletic subjects at neutral position and 10° dorsiflexion of the ankle joint (P < 0.05). No significant difference in stiffness was found between the non-dominant and dominant lower limbs either in amateur basketball players or in generally healthy subjects (P > 0.05). A significant positive correlation was obtained between stiffness of the AT and medial gastrocnemius (MG) in amateur basketball players (neutral position: r = 0.726 and P = 0.001; dorsiflexion 10°: r = 0.687 and P = 0.001). The amateur basketball players exhibit significantly higher stiffness value in Achilles and gastrocnemius. This is possibly caused by repeated training effects. The symmetric stiffness of the AT and gastrocnemius exists both in amateur basketball players and generally healthy subjects. A significant correlation between the AT and the MG was found in amateur basketball players.

The Reliability of MyotonPRO in Assessing Masseter Muscle Stiffness and the Effect of Muscle Contraction.

BACKGROUND Temporomandibular disorders (TMD) are accompanied by masticatory muscle-related pain, making it meaningful to assess the stiffness of the masticatory muscles. The present study investigated the intra- and inter-operator reliabilities of MyotonPRO for assessing the elasticity of masseter muscles, to determine minimal detectable changes, and to quantify changes in stiffness from conditions of relaxation to maximal contraction. MATERIAL AND METHODS Twenty healthy subjects (10 men and 10 women) were recruited. The stiffness of their masseter muscles was quantified with MyotonPRO in both relaxed and maximal contraction conditions. Two experienced operators (A and B) measured stiffness on the same day, and operator A repeated this procedure 5 days later. RESULTS Intra-rater reliability was good (ICC=0.78) and inter-operator reliability was excellent (ICC=0.95) for assessing masseter muscle stiffness with MyotonPRO. The mean stiffness of the masseter muscle on the dominant side was 369.5 N/m under relaxed conditions and 618.3 N/m at maximum bite force, an increase of 67.4%. Stiffness on the dominant and non-dominant sides did not differ significantly under both conditions (P>0.05). CONCLUSIONS MyotonPRO is a reliable method for quantifying the stiffness of the masseter muscle and monitoring its changes under different contraction conditions.

Objective Assessment of Regional Stiffness in Achilles Tendon in Different Ankle Joint Positions Using the MyotonPRO.

BACKGROUND Achilles tendinopathy commonly occurs in specific regions of the tendon, and Achilles tendon stiffness can be related to local pathological changes in the tendon. The MyotonPRO is a new handheld device that conveniently assesses stiffness of muscles and tendons. This study aimed to 1) evaluate the intra- and inter-rater reliability of stiffness measurements of the Achilles tendon at different ankle positions, 2) investigate the modulation of stiffness at different ankle joint angles, and 3) examine the differences between 2 regions of Achilles tendon stiffness. MATERIAL AND METHODS Thirty healthy young adults (15 men and 15 women) participated in this study. The regional Achilles tendon stiffness at 0 cm (AT-0) and 6 cm (AT-6) above the tendon insertion were evaluated by the MyotonPRO in the neutral position and 10° dorsiflexion of the ankle joint. Measurements of stiffness were taken by 2 raters on the first day and 5 days later. The stiffness data were compared by repeated measures analysis of variance (ANOVA). RESULTS The intra- and inter-rater reliability of stiffness measurements at AT-0 and AT-6 for each ankle position were good (all intraclass correlation coefficients >0.84). A significant modulation of Achilles tendon stiffness was obtained at different ankle joint angles (P<0.05). Stiffness at AT-0 was higher than at AT-6 (P<0.05) in both positions. CONCLUSIONS These results suggest the MyotonPRO reliably assessed Achilles tendon stiffness and monitors its modulation, and tendon stiffness increased with ankle dorsiflexion. Stiffness was also nonuniform along the length of the tendon.