Physiological Strain Research Articles

Physical and social wellbeing of family caregivers of persons with hepatitis B associated chronic liver disease in Ghana: a qualitative study

BackgroundHepatitis B is one of the most common viral (HBV)infections that affect the liver. Infection with the virus may result in varying severity of liver disease which may be acute or chronic. Though most people recover from the infection, about 5 − 10% of cases lead to chronic infection. Persons who develop HBV-related debilitating liver disease will likely require informal care from family caregivers.AimThis study sought to explore the physical and social wellbeing of family caregivers of persons with hepatitis B-associated chronic liver disease in a tertiary hospital in the Central region of Ghana.MethodsThis study adopted an exploratory, descriptive qualitative research design. We used a purposive sampling technique and a semi-structured interview guide to interview eighteen participants. The Quality of Life (QoL) model applied to family caregivers underpinned the study and guided the formulation of study objectives. Data analysis followed Braun and Clarke’s procedure for thematic content analysis. Similar codes were grouped into subthemes, and similar subthemes were grouped into major themes. The consolidated criteria for reporting qualitative research (coreq) checklist was used as a guide for writing the study.ResultsTwo major themes emerged from the study: physical wellbeing and social wellbeing. Seven subthemes were also identified: physical body changes and physiological body changes (physical wellbeing) and role strain, social isolation, financial impact, affection/sexual function, and support social wellbeing). These central themes aligned with two domains of the QoL model applied to family caregivers.ConclusionFamily caregivers of persons with HB-associated liver disease suffer ill health due to the burden of physical care for their sick relatives and neglect their health due to time constraints. They also experience role strain as they cannot attend to other family responsibilities and feel socially isolated since they spend all their time caring for a sick family member.

Effect of Work-to-Rest Cycles on Cardiovascular Strain and Maximal Oxygen Uptake during Heat Stress.

Cardiovascular drift-a progressive increase in heart rate (HR) and decrease in stroke volume (SV) during prolonged exercise-is exacerbated by heat stress and thermal strain, and often accompanied by a decrease in work capacity (indexed as maximal oxygen uptake [V.O2max]). To attenuate physiological strain during work in the heat, use of work:rest ratios is recommended by the National Institute for Occupational Safety and Health. The purpose of this study was to test the hypothesis that during moderate work in hot conditions, utilizing the recommended 45:15 min work:rest ratio would result in cardiovascular drift 'accumulating' over consecutive work:rest cycles and accompanying decrements in V.O2max. Eight people (5 women; (mean ± SD) age = 25 ± 5 y; body mass = 74.8 ± 11.6 kg; V.O2max = 42.9 ± 5.6 mL·kg-1·min-1) performed 120 min of simulated moderate work (201-300 kcal·h-1) in hot conditions (indoor wet-bulb globe temperature = 29.0 ± 0.6 °C). Participants completed two 45:15 min work:rest cycles. Cardiovascular drift was evaluated at 15 and 45 min of each work bout; V.O2max was measured after 120 min. On a separate day, V.O2max was measured after 15 min under identical conditions for comparison before and after cardiovascular drift occurred. HR increased 16.7% (18 ± 9 beats·min-1, p = 0.004) and SV decreased 16.9% (-12.3 ± 5.9 mL, p = 0.003) between 15 and 105 min, but V.O2max was unaffected after 120 min (p = 0.14). Core body temperature increased 0.5 ± 0.2 °C (p = 0.006) over 2 h. Recommended work:rest ratios preserved work capacity but did not prevent the accumulation of cardiovascular and thermal strain.

The multiscale characterization and constitutive modeling of healthy and type 2 diabetes mellitus Sprague Dawley rat skin.

In type 2 diabetes mellitus (T2DM), elevated glucose level impairs the biochemistry of the skin which may result in alteration of its mechanical and structural properties. The several aspects of structural and mechanical changes in skin due to T2DM remain poorly understood. To fill these research gaps, we developed a non-obese T2DM rat (Sprague Dawley (SD)) model for investigating the effect of T2DM on the in vivo strain stress state, mechanical and structural properties of skin. In vivo strain and mechanical anisotropy of healthy and T2DM skin were measured using the digital imaging correlation (DIC) technique and DIC coupled bulge experiment, respectively. Fluorescence microscopy and histology were used to assess the collagen and elastin fibers microstructure whereas nanoscale structure was captured through atomic force microscopy (AFM). Based on the microstructural observations, skin was modeled as a multilayer membrane where in and out of plane distribution of collagen fibers and planar distribution of elastin fibers were cast in constitutive model. Further, the state of in vivo stresses of healthy and T2DM were measured using model parameters and in vivo strain in the constitutive model. The results showed that T2DM causes significant loss in in vivo stresses (p < 0.01) and increase in anisotropy (p < 0.001) of skin. These changes were found in good correlation with T2DM associated alteration in skin microstructure. Statistical analysis emphasized that increase in blood glucose concentration (HbA1c) was the main cause of impaired biomechanical properties of skin. The presented data in this study can help to understand the skin pathology and to simulate the skin related clinical procedures. STATEMENT OF SIGNIFICANCE: Our study is significant as it presents findings related to the effect of T2DM on the physiologic stress strain, structural and mechanical response of SD rat skin. In this study, we developed a non-obese T2DM SD rat model which mimics the phenotype of Asian type 2 diabetics (non-obese). Several structural and mechanical characterization techniques were explored for multiscale characterization of healthy and T2DM skin. Further, based on microstructural information, we presented the constitutive models that incorporate the real microstructure of skin. The presented results can be helpful to simulate the realistic mechanical response of skin during various clinical trials.

Increased physical workload in home care service is associated with reduced recovery from work

ObjectiveThis study investigated the physical workload of home care service workers and determined whether the different intensities of physical work strain experienced by home care nurses have different impacts on their recovery from work.MethodsPhysical workload and recovery were measured among 95 home care nurses based on heart rate (HR) and heart rate variability (HRV) recordings during one work shift and the following night. Differences in the physical work strain were compared between younger (≤ 44-year-old) and older (≥ 45-year-old) employees and between morning and evening shifts. To determine the effects of occupational physical activity on recovery, HRV at all time points (during the workday, when awake and asleep, and whole measurement) in relation to the amount of occupational physical activity was examined.ResultsThe average physiological strain during the work shift, measured as metabolic equivalent (MET), was 1.8 ± 0.5. Moreover, the occupational physical demands in relation to maximal capacity were higher for the older employees. The results of the study showed that a higher occupational physical workload reduced the HRV of home care workers during the workday, leisure time, and sleep.ConclusionsThese data indicate that increased occupational physical workload is associated with reduced recovery among home care workers. Therefore, decreasing occupational strain and ensuring sufficient recovery is recommended.

Durability is improved by both low and high intensity endurance training.

Introduction: This is one of the first intervention studies to examine how low- (LIT) and high-intensity endurance training (HIT) affect durability, defined as 'time of onset and magnitude of deterioration in physiological-profiling characteristics over time during prolonged exercise'. Methods: Sedentary and recreationally active men (n = 16) and women (n = 19) completed either LIT (average weekly training time 6.8 0.7h) or HIT (1.6 0.2h) cycling for 10 weeks. Durability was analyzed before and after the training period from three factors during 3-h cycling at 48% of pretraining maximal oxygen uptake (VO2max): 1) by the magnitude and 2) onset of drifts (i.e. gradual change in energy expenditure, heart rate, rate of perceived exertion, ventilation, left ventricular ejection time, and stroke volume), 3) by the 'physiological strain', defined to be the absolute responses of heart rate and its variability, lactate, and rate of perceived exertion. Results: When all three factors were averaged the durability was improved similarly (time x group p = 0.42) in both groups (LIT: p = 0.03, g = 0.49; HIT: p = 0.01, g = 0.62). In the LIT group, magnitude of average of drifts and their onset did not reach statistically significance level of p < 0.05 (magnitude: 7.7 6.8% vs. 6.3 6.0%, p = 0.09, g = 0.27; onset: 106 57min vs. 131 59 min, p = 0.08, g = 0.58), while averaged physiological strain improved (p = 0.01, g = 0.60). In HIT, both magnitude and onset decreased (magnitude: 8.8 7.9% vs. 5.4 6.7%, p = 0.03, g = 0.49; onset: 108 54min vs. 137 57 min, p = 0.03, g = 0.61), and physiological strain improved (p = 0.005, g = 0.78). VO2max increased only after HIT (time x group p < 0.001, g = 1.51). Conclusion: Durability improved similarly by both LIT and HIT based on reduced physiological drifts, their postponed onsets, and changes in physiological strain. Despite durability enhanced among untrained people, a 10-week intervention did not alter drifts and their onsets in a large amount, even though it attenuated physiological strain.

Fluid Replacement Strategies and Heart Rate Variability Recovery Following Prolonged Exercise in the Heat and Mild Dehydration

Background: In sporting and combat settings, optimal fluid replacement is rarely achieved, exacerbating physiological strain. It is unknown if prescribed fluid replacement following exercise in heat impacts heart rate variability (HRV). Purpose: Compare prescribed drinking (PD) and ad libitum (AL) fluid replacement on HRV following exercise in heat. Methods: Twelve participants (26 ± 5 years, VO2max: 58.44 ± 7.05 mL·kg−1·min−1) completed three trials in heat (36 °C, 36% humidity) on separate days, and were placed into groups, PD or AL. Recovery was assessed ~24 h later (hydration and HRV). HRV time and frequency was measured using a 3-lead electrocardiogram. Two-way repeated measures analysis of variance measured changes in HRV pre-trial, post-trial, and follow-up between groups. Data reported: p-value, mean difference (MD). Results: Fluid consumption was greater in PD during recovery (p = 0.012, MD = 1245 mL). Both groups were euhydrated at follow-up. HRV time (p &lt; 0.001, MD = 24.23) and frequency (p &lt; 0.001, MD = −1.98 ms2) decreased post-trial and increased by follow-up (time, p &lt; 0.001, MD = −32.12; frequency, p &lt; 0.001, MD = 2.38 ms2). HRV was similar between groups (p &gt; 0.05). Conclusions: Replacing ≥60% fluid sufficiently rehydrates and restores HRV 24 h post-exercise in heat and mild dehydration (BML ≤ 3%). Prescribed fluid consumption during recovery was ~30% greater. Additional measures of recovery sensitive to heat strain may provide a more holistic understanding of specific mechanisms of recovery.

Can mixed circuit training elicit the recommended exercise intensity and energy expenditure in people after stroke?

ABSTRACT Purpose To investigate whether mixed circuit training (MCT) elicits the recommended exercise intensity and energy expenditure in people after stroke, and to establish the between-day reproducibility for the percentages of heart rate reserve (%HRR), oxygen uptake reserve (%VO2R), and energy expenditure elicited during two bouts of MCT. Methods Seven people aged 58 (12) yr, who previously had a stroke, performed a cardiopulmonary exercise test, a non-exercise control session, and two bouts of MCT. The MCT included 3 circuits of 10 resistance exercises at 15-repetition maximum intensity, with each set of resistance exercise interspersed with 45-s of walking. Expired gases were collected during the MCT and control session and for 40 min afterward. Control session was necessary to calculate the net energy expenditure associated with each bout of MCT. Results Mean %VO2R (1st MCT: 51.1%, P = .037; 2nd MCT: 54.0%, P = .009) and %HRR (1st MCT: 66.4%, P = .007; 2nd MCT: 67.9%, P = .010) exceeded the recommended minimum intensity of 40%. Both %VO2R (P = .586 and 0.987, respectively) and %HRR (P = .681 and 0.237, respectively) during the 1st and 2nd bouts of MCT were not significantly different to their corresponding gas exchange threshold values derived from cardiopulmonary exercise testing. Mean net total energy expenditure significantly exceeded the minimum recommend energy expenditure in the 1st (P = .048) and 2nd (P = .023) bouts of MCT. Between-day reproducibility for %HRR, %VO2R, and energy expenditure was excellent (ICC: 0.92–0.97). Conclusions MCT elicited physiological strain recommended for improving health-related fitness in people after stroke and these responses demonstrated excellent between-day reproducibility.

A hybrid deep leaning model for prediction and parametric sensitivity analysis of noise annoyance.

Noise annoyance is recognized as an expression of physiological and psychological strain in acoustical environment. The studies on prediction of noise annoyance and parametric sensitivity analysis of factors affecting it have been rarely reported in India. A hybrid ConvLSTM technique was developed in the study to predict traffic-induced noise annoyance in 484 people based on ambient noise levels, as well as survey information. Ambient noise levels were obtained at different locations of Dhanbad city using sound level meter at varying intervals, viz. 09AM-12PM, 03PM-06PM, and 08PM-11PM. The proposed method was compared with some well-known neural network techniques such as K-nearest neighbors (KNN), artificial neural network (ANN), recurrent neural network (RNN), and long-short-term memory (LSTM). The experimental results indicate that the proposed method outperforms other techniques and can be a reliable approach for prediction of noise annoyance with an accuracy of 93.8%. It can be concluded from noise maps that the noise levels in all locations of the Dhanbad city were higher than 70 dB(A) and noise sensitivity is the most important input variable of traffic-induced noise annoyance, followed by honking noise, education, exposure hours, LAeq, sleeping disorder, and chronic disease. The study shall facilitate in developing a decision support tool for prediction of noise annoyance and promoting implementation of suitable public policy in urban cities.

The other side of emotional support: The moderating role of personality in the relations between emotionally‐valenced support elicitation experiences and strain

AbstractRecent organizational research has begun focusing on alternative perspectives of the social support dynamic. One of these perspectives is the potential support provider perspective, which captures the social support dynamic from the view of employees put in position to potentially provide social support. Empirical findings concerning this perspective are scant and thus warrant additional research. The present study, using a large, occupationally heterogenous two‐wave sample (N = 447), further explored relations between strain and support elicitation experiences that are emotionally‐valenced, or SEE‐E, from the potential support provider perspective. The role of individual differences in influencing these relations was also investigated. Using hierarchical regression, we found that SEE‐E was related to key forms of psychological (work‐related burnout), behavioral (hostility), and physiological (the presence of physical symptoms) strain. Furthermore, we found that higher levels of agreeableness strengthened the relations between SEE‐E and work‐related burnout, and higher levels of conscientiousness weakened the relations between SEE‐E and hostility. Results from this study contribute to the nascent findings surrounding the potential support provider perspective of the workplace social support dynamic and further demonstrate the importance of individual differences to stressor‐strain dynamics.

Peak performance and cardiometabolic responses of modern US army soldiers during heavy, fatiguing vest-borne load carriage

IntroductionPhysiological limits imposed by vest-borne loads must be defined for optimal performance monitoring of the modern dismounted warfighter. PurposeTo evaluate how weighted vests affect locomotion economy and relative cardiometabolic strain during military load carriage while identifying key physiological predictors of exhaustion limits. MethodsFifteen US Army soldiers (4 women, 11 men; age, 26 ± 8 years; height, 173 ± 10 cm; body mass (BM), 79 ± 16 kg) performed four incremental walking tests with different vest loads (0, 22, 44, or 66% BM). We examined the effects of vest-borne loading on peak walking speed, the physiological costs of transport, and relative work intensity. We then sought to determine which of the cardiometabolic indicators (oxygen uptake, heart rate, respiration rate) was most predictive of task failure. ResultsPeak walking speed significantly decreased with successively heavier vest loads (p < 0.01). Physiological costs per kilometer walked were significantly higher with added vest loads for each measure (p < 0.05). Relative oxygen uptake and heart rate were significantly higher during the loaded trials than the 0% BM trial (p < 0.01) yet not different from one another (p > 0.07). Conversely, respiration rate was significantly higher with the heavier load in every comparison (p < 0.01). Probability modeling revealed heart rate as the best predictor of task failure (marginal R2, 0.587, conditional R2, 0.791). ConclusionHeavy vest-borne loads cause exceptional losses in performance capabilities and increased physiological strain during walking. Heart rate provides a useful non-invasive indicator of relative intensity and task failure during military load carriage.

Effects of liquid cooling garment on physiological and psychological strain of firefighter in hot and warm environments

This study aimed to explore the effects of a liquid cooling garment on the physiological and psychological strains of firefighters. Twelve participants wearing firefighting protective equipment with the liquid cooling garment (LCG group) and without the liquid cooling garment (CON group) were recruited to conduct human trials in a climate chamber. During the trials, physiological parameters (mean skin temperature (Tsk), core temperature (Tc), and heart rate (HR)) and psychological parameters (thermal sensation vote (TSV), thermal comfort vote (TCV), and rating of perceived exertion (RPE)) were measured continuously. The heat storage, sweating loss, physiological strain index (PSI), and perceptual strain index (PeSI) were calculated. The results indicated that the liquid cooling garment decreased the mean skin temperature (maximum value of 0.62 °C), scapula skin temperature (maximum value of 1.90 °C), sweating loss (26%), and PSI (0.95 scales) with a significant difference (p < 0.05) at some time points when compared with the CON group. Moreover, the liquid cooling garment had little influence (p > 0.05) on core temperature, heart rate, TSV, TCV, RPE, and PeSI. The association analysis indicated that psychological strain had the potential to predict physiological heat strain with an R2 value of 0.86 between the PeSI and PSI. This study offers insights into the evaluation of cooling system performance, the design of next-generation cooling systems, and the improvement of firefighters’ benefits.

Association between haemoglobin A1c and whole-body heat loss during exercise-heat stress in physically active men with type 2 diabetes.

What is the central question of this study? Is the impairment in heat dissipation during exercise observed in men with type 2 diabetes related to glycaemic control (indexed by glycated haemoglobin; haemoglobin A1c )? What is the main finding and its importance? No association was found between haemoglobin A1c (range: 5.1-9.1%) and whole-body heat loss in men with type 2 diabetes during exercise in the heat. However, individuals with elevated haemoglobin A1c exhibited higher body core temperature and heart rate responses. Thus, while haemoglobin A1c is not associated with heat loss per se, it may still have important implications for physiological strain during exercise. Type 2 diabetes is associated with a reduced capacity to dissipate heat. It is unknown whether this impairment is related to glycaemic control (indexed by glycated haemoglobin; haemoglobin A1c ) is unknown. We evaluated the association between haemoglobin A1c and whole-body heat loss (via direct calorimetry), body core temperature, and heart rate in 26 physically active men with type 2 diabetes (43-73 years; HbA1c 5.1-9.1%) during exercise at increasing rates of metabolic heat production (∼150, 200, 250Wm-2 ) in the heat (40°C, ∼17% relative humidity). Haemoglobin A1c was not associated with whole-body heat loss (P=0.617), nor the increase in core temperature from pre-exercise (P=0.347). However, absolute core temperature and heart rate were elevated ∼0.2°C (P=0.014) and ∼6beatsmin-1 (P=0.049), respectively, with every percentage point increase in haemoglobin A1c . Thus, while haemoglobin A1c does not appear to modify diabetes-related reductions in capacity for heat dissipation, it may still have important implications for physiological strain during exercise-heat stress.

The effect of evaporative cooling vests on the physiological and perceptual strain indices of construction workers

Aim: One of the most harmful agents in construction sites is heat exposure. The aim of this study was to evaluate the performance of new evaporative cooling vests in construction workers. Materials and Methods: This case–control study was implemented on 60 construction workers in hot conditions (air temperature 49.0°, relative humidity 5.5%) in the summer of 2019. In this study, 30 people with cooling vests (case group) and 30 people without cooling vests (control group) were working for 120 min in a hot environment. In both groups, heart rate oral temperature and wet bulb globe temperature (WBGT) index were measured. Moreover, the Perceptual Strain Index (PeSI) and Heat Strain Score Index (HSSI) questionnaires were completed by the workers. Data were analyzed after inter to SPSS16 software. Results: All of the WBGT values were higher than occupational exposure limit. The mean and standard deviation (SD) of the work heart rate in the case and control groups, was equal to 111.1 ± 7.6 beats per minute (bpm) and 114.3 ± 7.9 bpm respectively (P < 0.05). Also the average and SD of the oral temperature in the case and control groups, respectively, was equal to 36.36 ± 0.41 and 36.37 ± 0.55. There was no statistically significant difference. Mean and SD of Physiological Strain Index (PSI), in case and control groups, were 2.53 ± 0.66 and 3.64 ± 0.81, respectively. The mean and SD of the PeSI and the HSSI in the case group were 4.64 ± 0.79 and 10.12 ± 1.71, respectively, and in the control group, 6.41 ± 0.85 and 15.88 ± 0.1.43. Statistically, the difference between PSI, PeSI, and HSSI means was significant. Conclusions: This study results showed that hot environmental conditions were stressful for construction workers and also Iranian evaporative cooling vests (Hifitcool brand) were able to reduce perceptual and physiological heat strain in construction workers in the hot conditions.

Physiological and Psychological Stress Effects on the Rescue Units Involved in the Earthquake Rescue Operation in Turkey, with Particular Regard to the HUNOR Rescue Team

The purpose of this article is to present all the impacts on rescue teams that occur during rescue operations. The HUNOR rescue team, which searched for survivors for a week after the earthquake in Turkey, will be presented. The physiological and psychological strain is not negligible, so the article also makes a short detour about aftercare. At the end of the article, all the development directions that can contribute to the enhanced protection of a rescue team will be discussed, both in terms of personal protective equipment and organisational and health preparedness.

Can copper amino acid chelates reduce the physiological strain of growing rabbits under summer conditions?

This study was conducted at the Poultry Research Centre, Faculty of Agriculture, Alexandria University, Egypt, during the summer season (July and August months) 2018. For five weeks, until 63 d of age, a total number of 140 weaned V line rabbits were randomly distributed into seven groups of 20 rabbits each. Rabbits of groups 2 and 3 were fed basal diet plus copper sulphate (100 and 200 mg Cu-Sul/kg, respectively). Groups 4 and 5 were fed basal diet plus copper methionine (100 and 200 mg Cu-Meth/kg, respectively) and groups 6 and 7 were fed basal diet plus copper glycine (100 and 200 mg Cu-Gly/kg, respectively), while the first group was fed basal diet only as control. Rabbits fed diet supplemented with higher level (200 mg/kg) of Cu-Meth or Cu-Gly chelates had significantly higher body weight and daily body weight gain (P&lt;0.05) compared to those fed diets supplemented with both levels of Cu-Sul. Rabbits fed diets supplemented with Cu-Meth or Cu-Gly chelates had significantly increased (P&lt;0.05) red blood cells, lymphocyte, high-density lipoprotein and Cu values in blood. Within the studied Cu sources, serum total lipids values of rabbits were significantly lower than in the control group. However, serum total antioxidant capacity, glutathione peroxidase and superoxide dismutase were higher by both organic chelates studied than other groups. In general, copper supplementation improves productive performance and physiological status under summer conditions.

Delineating the impacts of air temperature and humidity for endurance exercise.

What is the central question of this study? What are the independent effects of air temperature and humidity on performance, physiological and perceptual responses during endurance exercise? What is the main finding and its importance? When examined independently, elevated air temperature increased heat strain and impaired aerobic exercise performance, but to a lesser extent than has been reported previously. These findings highlight the importance of absolute humidity relative to temperature when exercising or working under severe heat stress. Many studies have reported that ambient heat stress increases physiological and perceptual strain and impairs endurance exercise, but effects of air temperature per se remain almost unexamined. Most studies have used matched relative humidity, thereby exponentially increasing absolute humidity (water content in air) concurrently with temperature. Absolute (not relative) humidity governs evaporative rate and is more important at higher work rates and air temperatures. Therefore, we examined the independent effects of air temperature and humidity on performance, thermal, cardiovascular and perceptual measures during endurance exercise. Utilizing a crossover design, 14 trained participants (7 females) completed 45min fixed-intensity cycling (70% ) followed by a 20-km time trial in each of four environments: three air temperatures at matched absolute humidity (Cool, 18°C; Moderate, 27°C; and Hot, 36°C; at 1.96kPa, air velocity ∼4.5m/s), and one at elevated humidity (Hot Humid, 36°C at 3.92kPa). Warmer air caused warmer skin (0.5°C/°C; P<0.001), higher heart rate (1bpm/°C; P<0.001), sweat rate (0.04l/h/°C; P<0.001) and thermal perceptions during fixed-intensity exercise, but minimally affected core temperature (<0.01°C/°C; P=0.053). Time-trial performance was comparable between Cool and Moderate (95% CI: -1.4, 5.9%; P=0.263), but 3.6-6% slower in Hot (95% CI: ±2.4%; P≤0.006). Elevated humidity increased core temperature (P<0.001), perceived temperature and discomfort but not skin temperature or heart rate, and reduced mean blood pressure (P=0.046) during fixed-intensity exercise. Elevated humidity impaired time-trial performance by 3.4% (95% CI: ±2.2%; P=0.006). In conclusion, these findings quantify the importance of absolute humidity alongside air temperature when exercising under severe heat stress.

Surgeons Experience More Physiologic Stress and Strain During Revision Than Primary Total Joint Arthroplasty

BackgroundRevision total knee arthroplasty (rTKA) and total hip arthroplasty (rTHA) procedures are more complex than primary TKA and THA, but their physiologic burden to the surgeon has not been quantified. While rTKA and rTHA have longer operative times, it is unknown whether differences exist in stress and strain compared to primary TKA and primary THA. The study was conducted to elicit whether differences exist in surgeon physiological response while performing rTKA and rTKA compared to primary TKA and primary THA. MethodsWe evaluated a prospective cohort study of 70 consecutive cases (23 primary TKAs, 12 primary THAs, 16 rTKAs, and 19 rTHAs). Two high-volume fellowship-trained arthroplasty surgeons wore a smart vest that recorded cardiorespiratory data while performing primary THA, primary TKA, rTHA, and rTKA. Heart rate (beats/minute), stress index (correlates with sympathetic activation), respiratory rate (respirations/minute), minute ventilation (L/min), and energy expenditure (Calories) were collected for every case, along with patient body mass index (kilograms/meter2) and working operative time (minutes). T-tests were used to assess for differences between the two groups. ResultsCompared to primary TKA, performing rTKAs had a significantly higher surgeon stress index (17 versus 15; P = .035), heart rate (104 versus 99; P = .007), energy expenditure per case (409 versus 297; P = .002), and a significantly lower heart rate variability (11 versus 12; P = .006). Compared to primary THA, performing rTHA had a significantly higher energy expenditure per case (431 versus 307; P = .007) and trended towards having a higher surgeon stress index (16 versus 14; P = .272) and a lower heart rate variability (11 versus 12; P = .185), although it did not reach statistical significance. ConclusionSurgeons experience higher physiological stress and strain when performing rTKA and rTHA compared to primary TKA and primary THA. This study provides objective data on what many surgeons feel and should promote further research on the specific stress and strain felt by surgeons who perform revision arthroplasty procedures.

Influence of Single-Nucleotide Polymorphisms on Vitamin D Receptor Expression in Periodontal Ligament Fibroblasts as a Response to Orthodontic Compression.

This study aimed to evaluate if single-nucleotide polymorphisms (SNPs) in the vitamin D receptor (VDR) gene are associated with gene expression in human periodontal ligament (hPDL) fibroblasts under simulated orthodontic compressive force. hPDL samples from 57 patients were used. A physiological compressive strain was performed to simulate orthodontic tooth movement in pressure areas under cell culture conditions. The RNA from hPDL fibroblasts was isolated to determine the relative gene expression (mRNA) of the VDR. The DNA was also isolated for the genotyping analysis of five SNPs in the VDR gene: BglI (rs739837, G/T), BsmI (rs1544410, T/C), ApaI (rs7975232, A/C), FokI (rs2228570, A/G), and TaqI (rs731236, A/G). Real-time polymerase chain reaction was used for both analyses. Kruskal-Wallis tests were used to compare VDR expression among genotypes of each SNP. A linear regression analysis was performed to evaluate SNP-SNP interaction. An established alpha of 5% was used. The relative mRNA VDR expression according to the genotypes in the SNPs BglI, BsmI, ApaI, FokI, and TaqI was not statistically significantly different (p &gt; 0.05). The SNP-SNP interaction evaluated by regression analysis did not demonstrate any statistically significant association. No association was observed (p &gt; 0.05). In conclusion, the SNPs BglI (rs739837), BsmI (rs1544410), ApaI (rs7975232), FokI (rs2228570), and TaqI (rs731236) did not show an impact on VDR gene expression in hPDL fibroblasts under simulated orthodontic compressive force.

Systems Biology Analysis of Temporal Dynamics That Govern Endothelial Response to Cyclic Stretch.

Endothelial cells in vivo are subjected to a wide array of mechanical stimuli, such as cyclic stretch. Notably, a 10% stretch is associated with an atheroprotective endothelial phenotype, while a 20% stretch is associated with an atheroprone endothelial phenotype. Here, a systems biology-based approach is used to present a comprehensive overview of the functional responses and molecular regulatory networks that characterize the transition from an atheroprotective to an atheroprone phenotype in response to cyclic stretch. Using primary human umbilical vein endothelial cells (HUVECs), we determined the role of the equibiaxial cyclic stretch in vitro, with changes to the radius of the magnitudes of 10% and 20%, which are representative of physiological and pathological strain, respectively. Following the transcriptome analysis of next-generation sequencing data, we identified four key endothelial responses to pathological cyclic stretch: cell cycle regulation, inflammatory response, fatty acid metabolism, and mTOR signaling, driven by a regulatory network of eight transcription factors. Our study highlights the dynamic regulation of several key stretch-sensitive endothelial functions relevant to the induction of an atheroprone versus an atheroprotective phenotype and lays the foundation for further investigation into the mechanisms governing vascular pathology. This study has significant implications for the development of treatment modalities for vascular disease.

Heat strain while wearing pesticide protective clothing in hot environments: Effects of textile physical properties and ambient humidity

The purpose of this study was to investigate heat strain while wearing pesticide protective clothing (PPC) with different physical properties in hot environments. Eight young males participated in the following three PPC conditions [polyester/cotton work clothing (IT = 1.26 clo, Ret = 42.0 m2·PaW−1), Tyvek coverall (1.16 clo, 47.5 m2·PaW−1), and commonly used nylon suit with a microporous membrane (1.42 clo, 54.1 m2·PaW−1)] and in two environmental conditions (32 °C with 50% RH and 32 °C with 80% RH). All physiological variables (rectal and mean skin temperature, heart rate, and physiological strain index) and most subjective perceptions showed greater values in the 80% RH than in the 50% RH environment (all p < 0.05). Physiological burden was greater in the commonly used nylon suit condition than in the polyester/cotton work clothing condition (all p < 0.05), but in many variables there were no statistical differences between the Tyvek and nylon suit condition, especially in the 80% RH environment. There were no differences in humidity sensation during exercise among the PPC conditions, whereas, during recovery, subjects felt more humid in the Tyvek or nylon suit than in the polyester/cotton work clothing condition (p < 0.05). These results indicate that the 30%-higher humidity induced a greater physiological burden. However, physiological or subjective burden would not always be proportional or inversely proportional to the physical property level of PPC but was affected more by heat exchange modes between the human body and ambient environments.