Forward Stepwise Multiple Linear Regression Research Articles

Sex differences in heat stress vulnerability among middle-aged and older adults (PSU HEAT Project).

Individuals over the age of 65 yr are the most vulnerable population during severe environmental heat events, experiencing worse health outcomes than any other age cohort. The risk is greater in older women than in age-matched men; however, whether that reflects a greater susceptibility to heat in women, or simply population sex proportionality, is unclear. Seventy-two participants (29 M/43 F) aged 40-92 yr were exposed to progressive heat stress at a metabolic rate designed to reflect activities of daily living. Experiments were conducted in both hot-dry (HD; up to 53°C; ≤25% rh) and warm-humid (WH; ∼35°C; ≥50% rh) environments. After critical limits were determined for each condition, forward stepwise multiple linear regression analyses were conducted with net metabolic rate (Mnet) and age entered into the model first, followed by sex, body mass (mb), maximal oxygen consumption (V̇o2max), body surface area, and LDL cholesterol. After accounting for Mnet and age, sex further improved the regression model in the HD environment ([Formula: see text] = 0.34, P < 0.001) and the WH environment ([Formula: see text] = 0.36, P < 0.005). Sex explained ∼15% of the variance in critical environmental limits in HD conditions and 12% in WH conditions. Heat compensability curves were shifted leftward for older women, indicating age- and sex-dependent heat vulnerability compared with middle-aged women and older men in WH (P = 0.007, P = 0.03) and HD (P = 0.001, P = 0.01) environments. This reflects the heterogeneity of thermal-balance thresholds associated with aging relative to those seen in young adults and suggests that older females are more vulnerable than their age-matched male counterparts.NEW & NOTEWORTHY In contrast to young adults, there are sex differences in critical environmental limits in middle-aged and older adults. Older women exhibit lower critical environmental limits in both humid and dry extreme environments demonstrated by a leftward shift in heat compensability curves. These data confirm a true sex difference in heat vulnerability of older adults and support the epidemiological mortality data from environmental heat waves.

Machine learning-based QSAR modeling, molecular docking, dynamics simulation studies for cytotoxicity prediction in MDA-MB231 triple-negative breast cancer cell line

Triple-negative breast cancer (TNBC) is the most aggressive cancer type that tests negative for progesterone, estrogen, and HER2 protein receptors. Therefore, TNBC is unlikely to respond either to drugs that target HER2 receptors or to hormonal therapy drugs. In the present study, 2D-QSAR model was developed to predict the inhibitory concentration (IC50) of terpene derivatives against human breast cancer metastatic cell line MDA-MB231, using V-Life MDS v4.5, module. The model was developed using the forward stepwise multiple linear regression method, with a regression coefficient (r2) of 0.86, and a cross-validated r2 (q2) of 0.8448. Molecular descriptors namely electronegativity (Epsilon-3), carbon atoms separated through five bond distances (T_C_C_5), Sum of Electrotopological state indices of –CH2 group (SssCH2count), Dipole moment of coordinate-z (Zcomp Dipole), and Distance between highest positive and negative electrostatic potential on van-der Waals surface area (Most +ve & -ve Potential Distance) were found to be the most potent contributing chemical descriptors for cytotoxicity against TNBC MDA-MB231 cell line. Additionally, binding affinities and interaction patterns revealed that the proposed compounds exhibit good binding affinities and substantial stability with c-Met-and β-tubulin receptors, as assessed by docking studies. Molecular dynamics simulations (100 ns) and binding free energy calculations were also performed using the MMGBSA method. The pharmacokinetic and eADME/T analysis of predicted compounds were assessed through Discovery Studio software. These findings may be of immense importance in the optimization and development of dual inhibitory potent anti-cancer inhibitors against the MDA-MB231 TNBC cell line. Moreover, this novel QSAR based prediction model/method is implemented in R-package and software tool developed for virtual screening purposes and available online for download through the public repository GitHub.

Influence of Individual Characteristics on Critical Environmental Limits in Middle-aged and Older Adults (PSU HEAT Project)

Critical environmental limits represent the temperature/humidity combinations at which heat balance can no longer be maintained for a given metabolic rate. Individual characteristics (e.g., sex, body weight and size, and aerobic fitness) are known to alter environmental heat exchange as well as thermoregulatory effector responses and therefore may modify critical environmental limits. PURPOSE: To determine which individual characteristics, if any, may be associated with higher or lower critical environmental limits [combinations of ambient dry-bulb temperature (Tdb) and relative humidity (rh)] in middle-aged and older adults. Methods: Forty-eight male (n=16) and female (n=32) participants (63±11 yrs; range: 40-92 yrs) were exposed to progressive heat stress at a low metabolic rate designed to reflect activities of daily living. Experiments were conducted in both hot-dry (HD; up to 53°C; ≤25% rh) and warm-humid (WH; ~35°C; ≥50% rh) environments. After determining critical limits for each age group and condition, forward stepwise multiple linear regression analyses were conducted with net metabolic rate (Mnet) and age entered into the model first, followed by sex, body mass, Vȯ2max, body surface area, and LDL cholesterol. Results: After accounting for Mnet and age, both sex and body mass further significantly improved the regression model in the HD environment (R2adj = 0.41, p &lt; 0.001) whereas only sex (R2adj = 0.51, P &lt; 0.001) added significantly to the WH model. Sex explained 11% of the variance in critical environmental limits in HD conditions and 14% of the variance in WH conditions. In both WH and HD environments, females exhibited lower critical combinations of Tdb and rh than their male counterparts. Additionally, body mass was negatively related to critical environmental limits in the HD environments and accounted for 8% of the variance after metabolic rate and age were accounted for. CONCLUSION: These data indicate a modest influence of individual characteristics, specifically sex and body mass, on critical environmental limits in both WH and HD environments in adults between the ages of 40 and 92. SIGNIFICANCE/NOVELTY: These results contrast previously published data in young adults showing no significant contribution of individual characteristics to the upper limits of heat balance at low metabolic rates reflecting activities of daily living. This reflects the heterogeneity of thermal-balance thresholds associated with aging relative to those seen in young adults. NIH R01 AG067471 (WLK) and NIA Grant T32 AG049676 (RMC). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Structure-Activity Relationship Studies on VEGFR2 Tyrosine Kinase Inhibitors for Identification of Potential Natural Anticancer Compounds.

Over-expression of Vascular Endothelial Growth Factor Receptors (VEGFRs) leads to the hyperactivation of oncogenes. For inhibition of this hyperactivation, the USA Food Drug Administration (FDA) has approved many drugs that show adverse effects, such as hypertension, hypothyroidism, etc. There is a need to discover potent natural compounds that show minimal side effects. In the present study, we have taken structurally diverse known VEGFR2 inhibitors to develop a Quantitative Structure-Activity Relationship (QSAR) model and used this model to predict the inhibitory activity of natural compounds for VEGFR2. The QSAR model was developed through the forward stepwise Multiple Linear Regression (MLR) method. A developed QSAR model was used to predict the inhibitory activity of natural compounds. Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) assessment and molecular docking studies were performed. The binding stability of the natural compounds with VEGFR2 was elucidated through Molecular Dynamics (MD) simulation. The developed QSAR model against VEGFR2 showed the regression coefficient of the training dataset (r2) as 0.81 and the external regression coefficient of the test dataset (r2 test) 0.71. Descriptors, viz., electro-topological state of potential hydrogen bonds (maxHBint2, nHBint6), atom types (minssNH), maximum topological distance matrix (SpMAD_Dt), and 2D autocorrelation (ATSC7v), have been identified. Using this model, 14 natural compounds have been selected that have shown inhibitory activity for VEGFR2, of which six natural compounds have been found to possess a strong binding affinity with VEGFR2. In MD simulation, four complexes have shown binding stability up to 50ns. The developed QSAR model has identified 5 conserved activity-inducing physiochemical properties, which have been found to be correlated with the anticancer activity of the nonidentical ligand molecules bound with the VEGFR2 kinase. Lavendustin_A, 3'-O-acetylhamaudol, and arctigenin have been obtained as possible lead natural compounds against the VEGFR2 kinase.

Relationships between regional retinal sensitivities assessed by microperimetry and their corresponding retinal layer thicknesses in healthy middle‐aged subjects

Aims/Purpose: To investigate relationships between regional differential light sensitivity (DLS) and inner and outer retinal layer (IRL and ORL) thicknesses in healthy middle‐aged adults.Methods: Measurements were made in 42 eyes of 42 healthy individuals of mean age 51.3 ± 5.4 years (range 40–59 years), spherical equivalent (SE) between ±3.50 D and good visual acuity. Mesopic fundus‐controlled perimetry was used to measure regional DLS. Spectral‐domain optical coherence tomography (SD‐OCT) was used to measure IRL (ganglion cell‐related layer) and ORL thicknesses. DLS and retinal thickness measurements were recorded for five subfields: central fovea (1 mm diameter) and the quadrants temporal, nasal, superior, and inferior of a parafoveal ring of outer diameter 3 mm and inner diameter 1 mm. Relationships between regional DLS and corresponding IRL and ORL thicknesses were assessed through univariate and multivariate analysis.Results: Mean DLS measured in the inferior parafoveal ring quadrant was significantly correlated with mean IRL thickness (rho = −0.50; p = 0.0045). This correlation was negative, meaning that a thicker IRL was related to a worse DLS. No significant correlations emerged between mean DLS and corresponding ORL or IRL thicknesses for the other subfields. Subsequent forward stepwise multiple linear regression analysis to correct for potential confounding factors revealed that IRL thickness and SE emerged as significant predictors of DLS in the inferior quadrant (R2 model = 33%; p = 0.0004).Conclusions: A thicker macular IRL, possibly indicating transient gliosis, was associated with a worse DLS in healthy middle‐aged eyes.

Optimization of VO2 and VCO2 outputs for the calculation of resting metabolic rate using a portable indirect calorimeter.

This study aimed to compare the Cosmed K5 portable indirect calorimeter, using the mixing chamber mode and face mask, with a stationary metabolic cart when measuring the resting metabolic rate (RMR) and to derive fitting equations if discrepancies are observed. Forty-three adults (18-84 years) were assessed for their RMR for two 30-min consecutive and counterbalanced periods using a Cosmed K5 and an Oxycon Pro. Differences among devices were tested using paired sample Student's t-tests, and correlation and agreement were assessed using Pearson's correlation coefficients, intraclass correlation coefficient and Bland-Altman plots. Forward stepwise multiple linear regression models were performed to develop fitting equations for estimating differences among devices when assessing oxygen uptake (VO2 diff , mL·min-1 ) and carbon dioxide production (VCO2 diff , mL·min-1 ). Furthermore, the Oxycon Pro was tested before being confirmed as a reference device. Significant differences between devices were found in most metabolic and ventilatory parameters, including the primary outcomes of VO2 and VCO2 . These differences showed an overestimation of the Cosmed K5 in all metabolic outcomes, except for Fat, when compared to the Oxycon Pro. When derived fitting equations were applied (VO2 diff - 139.210 + 0.786 [weight, kg] + 1.761 [height, cm] - 0.941 [Cosmed K5 VO2 , mL·min-1 ]; VCO2 diff - 86.569 + 0.548 [weight, kg] + 0.915 [height, cm] - 0.728 [Cosmed K5 VCO2 , mL·min-1 ]), differences were minimized, and agreement was maximized. This study provides fitting equations which allow the use of the Cosmed K5 for reasonably optimal RMR determinations.

Determinants of clinical outcome and length of stay in acute care forensic psychiatry units

Criminological and sociodemographic variables, such as previous criminal convictions, increased risk of violence, early onset of mental disorder, antisocial personality, psychosis and low social support, have all been related to longer length of stay (LoS) and poorer outcome in long stay forensic services. The factors impacting on LoS and clinical response in acute care specialized units are poorly documented. To address this issue, we examined the psychiatric records of all cases admitted between January 1st and December 31th 2020 in the sole acute ward for detained persons located in the central prison of the Geneva County, Switzerland. Information on judicial status included pre-trial versus sentence execution, previous incarcerations, and age of the first incarceration. Sociodemographic data included age, gender, marital status, and education attainment. Previous inpatient stays prior to incarceration were recorded. All of the ICD-10 clinical diagnoses were made by two independent, board-certified psychiatrists blind to the scope of the study. The standardized assessment was based on the HoNOS (Health of Nation Outcome Scales) at admission and discharge, HONOS-secure at admission, HCR-20 (Historical Clinical Risk 20) version 2, PCL-R (Psychopathy Checklist Revised), and SAPROF (Structured Assessment of Protective Factors). Stepwise forward multiple linear regression models predicting the LoS and delta HONOS respectively were built with the above mentioned parameters. The selected variables were then used in univariate and multivariable regression models. Higher HCR-scores (mainly on clinical items), and longer LoS were related to higher delta HONOS scores. In contrast, cases in pre-trial detention showed a worst clinical outcome. In multivariable models, all three variables remained independent predictors of the clinical outcome and explained 30.7% of its variance. Only education and diagnosis of borderline personality were related to the LoS and explained 12.6% of its variance in multivariable models. Our results suggest that the use of acute wards specialized in forensic psychiatry are mainly useful for patients with prior inpatient care experience, and higher violence risk during sentence execution. In contrast, they seem to be less performant for persons in pre-trial detention that could benefit from less restrictive clinical settings.

Independent predictors and equation of six-minute walk test in post-cardiac surgery

BackgroundThe six-minute walk test (6MWT) has been used to evaluate postsurgical recovery in cardiac patients. No previous study has compared the 6MWT at follow-up with a baseline, or evaluated the long-term effects of cardiac surgery on post-discharge 6MWT ObjectivesTo identify the factors independently associated with 6MWD, and to develop an equation to predict 6MWT at the 4–6-week follow-up after post-cardiac surgery hospital discharge. MethodsPatient data of elective coronary artery bypass graft (CABG) or non-CABG surgery patients were retrospectively collected. The 6MWT was performed at hospital discharge and at the 4–6-week follow-up. Available demographic and clinical data of patients were analyzed to determine the independent factors of 6MWT. An equation to predict 6MWT were generated by forward stepwise multiple linear regression analysis. ResultsThe data of 275 patients (mean age: 62.20±14.57 years, 64.7% male) were analyzed. The mean 6MWT was 179.14±92.18 m at discharge, and increased to 335.20±115.51 m at the 4–6-week follow-up. The 6MWT at the 4–6-week follow-up was independently correlated with 6MWT at discharge, regular exercise, age, gender, and preoperative New York Heart Association (NYHA) classification. ConclusionThe independent predictors: 6MWT at discharge, regular exercise, age, gender, and NYHA classification were used to generate an equation to predict 6MWT at 4–6 weeks after hospital discharge.

The relationship of retinal vessel calibres with cardiovascular risk factors in apparently healthy young eyes

AbstractPurpose: Although retinal vascular calibre has been linked to increased cardiovascular (CV) risk, it remains unclear whether retinal vascular morphologic changes are already evident in young adults and correlate with modifiable CV risk factors. The purpose of this study was to explore the relationship of retinal arteriolar and venular calibre with CV risk factors and ocular parameters in healthy young subjects.Methods: A cross‐sectional study was performed in 52 apparently healthy subjects (mean 21.6 ± 2.2 years of age). Retinal vascular calibres were measured from fundus photographs using semi‐automated imaging software and expressed as central retinal arteriolar (CRAE) or venular (CRVE) equivalent and arterio‐venous ratio (AVR). CV risk factors and ocular parameters were assessed. Forward stepwise multiple linear regression analysis was used to detect the independent relationship between retinal vascular calibre and CV and ocular parameters.Results: Means for CRAE and CRVE were 191 ± 15.4 μm and 209 ± 15.8 μm respectively. The mean CRAE but not CRVE was significantly higher in women than in men (p = 0.009). Systolic blood pressure (SBP) and spherical equivalent were significant contributing factors to CRAE (SBP: p &lt; 0.001; SE: p = 0.021). However, CRVE was not significantly predicted by CV risk factors or ocular parameters. SBP was the only one independent contributor to AVR (p = 0.018).Conclusions: In young adults, higher SBP was found to be related to narrower retinal arterioles, but not to retinal venules. Sex and other confounding CV or ocular factors had no effect on the relationship of SBP and retinal vessel calibre.

The relationships between mesopic light sensitivity and macular inner and outer retinal layer thicknesses in older healthy adults

AbstractPurpose: Structural and functional markers are important for the early detection of neurodegenerative diseases of the eye. This study investigates the relationships between macular layer thicknesses and mesopic light sensitivity (MLS) in older healthy eyes.Methods: Measurements were made in 38 eyes of 38 healthy individuals of mean age 67 ± 5.6 years (range 60–80 years) and good visual acuity. MLS was measured with macular integrity assessment (MAIA) microperimetry at the central 10° diameter circle. MLSs at the central subfield (1° radius) and at four regions (temporal, nasal, superior, inferior) of the parafoveal ring (3°–5° radius of eccentricity) were registered. Total, inner, and outer retinal layer (IRL and ORL) thicknesses were measured in the macular region through spectral‐domain optical coherence tomography (SD‐OCT). Relationships between MLS and the retinal thickness in the corresponding macular region were examined using forward stepwise multiple linear regression analyses.Results: ORL and IRL thickness in the inferior parafoveal ring were significant contributing factors to the inferior MLS (ORL: p &lt; 0.0001; IRL: p = 0.0003; R2 model = 51%). Increased ORL thickness and decreased IRL thickness correlated with worse MLS. The total retinal thickness, age, sex, refractive error, axial length, retinal illuminance or visual acuity variables were not found to be significant predictors of MLS.Conclusions: ORL and IRL thicknesses predict inferior parafoveal MLS in healthy older eyes. The measurement of MLS in combination with macular layer thicknesses may be useful for detecting loss of sensitivity caused by early degenerative diseases of the retina.

Decreased adiponectin/leptin ratio relates to insulin resistance in adults with obesity.

Adipose tissue dysfunction is a key mechanism that leads to adiposity-based chronic disease. This study aimed to investigate the reliability of the adiponectin/leptin ratio (AdipoQ/Lep) as an adipose tissue and metabolic function biomarker in adults with obesity, without diabetes. Data were collected from a clinical trial conducted in 28 adults with obesity (mean body mass index: 35.4 ± 3.7 kg/m2) (NCT02169778). With the use of a forward stepwise multiple linear regression model to explore the relationship between AdipoQ/Lep and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), it was observed that 48.6% of HOMA-IR variance was explained by triacylglycerols, AdipoQ/Lep, and waist-to-hip ratio (P < 0.001), AdipoQ/Lep being the strongest independent predictor (Beta = -0.449, P < 0.001). A lower AdipoQ/Lep was correlated with higher body mass index (Rs = -0.490, P < 0.001), body fat mass (Rs = -0.486, P < 0.001), waist-to-height ratio (Rs = -0.290, P = 0.037), and plasma resistin (Rs = -0.365, P = 0.009). These data highlight the central role of adipocyte dysfunction in the pathogenesis of insulin resistance and emphasize that AdipoQ/Lep may be a promising early marker of insulin resistance development in adults with obesity.NEW & NOTEWORTHY Adiponectin/leptin ratio, triacylglycerols, and waist-to-hip ratio explained almost half of HOMA-IR variance in the context of obesity. This study provides evidence to support adipose tissue dysfunction as a central feature of the pathophysiology of obesity and insulin resistance. Early identification of individuals at higher risk of developing metabolic complications through adipose tissue dysfunction assessment and the staging of obesity and its transient phenotypes can contribute to improve therapeutic decision-making.

A regression-based rating prediction model for mobile-based puzzle games

Cell phones, nowadays, are used for not only making phone calls and sending messages but also for entertainment. Mobile-based games of various kinds are instrumental in acting as a source of entertainment. Player enjoyment is one of the major motivations in playing any kind of mobile game. The first model proposed for player enjoyment was Flow, which used eight different elements of enjoyment. GameFlow, a later model, was derived through mapping with the Flow model. Each element of GameFlow consists of a set of criteria for experiencing enjoyment while playing mobile games. Prediction of mobile games’ rating using aspects of player enjoyment can be extremely beneficial to mobile game designers. This work first provides a Regression-Based Rating Prediction Model (RBRPM) for Android-based puzzle games using elements of the GameFlow model. RBRPM is derived by applying Forward Stepwise Multiple Linear Regression on a data set consisting of 80 puzzle games. The data set is compiled by playing these games considering the criteria of all elements of the GameFlow model. RBRPM relies on five predictors, namely feedback, social interaction, concentration, clear goals, and player skills for predicting a games’ rating. Next, this work extends RBRPM by including not only additional criteria in the already identified elements but also adds three new elements i.e. fantasy, mystery, and thrill. The improved model (IRBRPM) uses 8 predictors. MMRE and PRED(x) are used as prediction accuracy metrics for assessing this model and K-fold cross-validation is used for model validation. These two steps provide encouraging results.

What facilitates hepatitis B and hepatitis C testing and the role of stigma among primary care patients in China?

Approximately 80% of primary healthcare facilities in China were ready to deliver hepatitis care services by 2021. This study aimed to assess hepatitis B and C test uptake, identify the factors associated with testing and determine the predictors of hepatitis stigma among primary care patients. We conducted a cross-sectional survey among patients seeking care in the family medicine and primary care unit of the University of Hong Kong-Shenzhen Hospital, China. Participants were 30 years or older and had not tested for HBV and HCV in the preceding 12 months. Test uptake was defined as self-reported previous HBV and HCV testing. Descriptive statistics, Chi-square test, forward multivariable logistic regression and stepwise multiple linear regression were conducted, and a p-value <.05 was deemed statistically significant. A total of 750 eligible patients completed the survey, and 54.5% (404 ± 0.9) were between 30 and 40 years old. Most participants were heterosexuals 98.0% (n=735), female 57.5% (n=431), married 78.3% (587) and earned ≤1500 USD per month 54.4% (n=408). A 66.1% (n=496) and 13.7% (n=103) self-reported previous HBV and HCV testing, respectively, and 62% (n=468) were vaccinated. HCV testing was associated with HBV testing (aOR=13.7, 95% CI:2.1-91.5); and HBV testing was associated with family history of HBV (aOR=2.4, 95%CI:1.1-5.5). Overall hepatitis stigma was about average and decreased with family history of HBV (p=.017). In conclusion, HCV testing uptake among primary care patients was low and needs to be further promoted. Integrating HBV and HCV testing interventions and fostering family-based support for disclosure could effectively improve testing uptake.

Vis-NIR-spectroscopy- and loss-on-ignition-based functions to estimate organic matter content of calcareous soils

ABSTRACT The study was carried out to derive pedotransfer (PTFs) and spectrotransfer (STF) functions to estimate soil organic matter (SOM) content measured by time-consuming and expensive Walkley–Black wet combustion (W-B), using SOM content obtained from loss on ignition (LOI) and spectra reflectance bands at visible (Vis) and near infrared (NIR) regions. In total, 171 soil samples were collected from calcareous soils of southern Iran. The SOM content of the samples was determined using W–B wet combustion (SOMW-B) and LOI at temperatures of 360 °C during 2 h (LOI360-2); 550 °C during 3 h (LOI550-3); and 375°C during 16 h (LOI375-16). For the spectroscopy method, partial least squares regression (SpectPLSR) and forward stepwise multiple linear regression (SpectSMLR) approaches were used for function development. The LOI360-2 procedure with R2 val of 0.9 for the validation dataset provided the best match with SOMW-B content. Furthermore, the SpectSMLR provided a STF using spectral reflectance bands at 495, 730, 970, 1906, 2262 and 2342 nm which predicted SOMW-B with R2 val of 0.87. Results indicated both the SpectSMLR and LOI360-2, as easy and inexpensive approaches, could be recommended to accurately assess SOM content of calcareous soils.

The Relationship Between High-intensity Functional Training Performance And Laboratory-based Measurements Of Fitness

To date, research has examined the physiological determinants of performance in standardized High-Intensity Functional Training (HIFT) workouts but not without the influence of HIFT familiarity. PURPOSE: To examine the predictive value of aerobic fitness, body composition, and total body strength on performance of two standardized HIFT workouts in HIFT-naïve participants. METHODS: Twenty-two recreationally trained individuals (males = 13, females = 9) underwent assessments of peak oxygen consumption (VO2 peak), ventilatory thresholds, body composition, and one repetition maximum tests for the back squat, deadlift, and overhead press in which the sum equaled the total strength. Participants also performed two standardized HIFT workouts: a scaled version of the 19.1 (as many sets of 19 wall balls followed by 19 calories on rower within 15 minutes) and a modified Fran (sets of 21, 15, and 9 repetitions of thrusters and burpees) to determine scores based on total repetitions completed and time-to-completion, respectively. Simple Pearson’s r correlations were used to determine the relationships between HIFT performance variables (19.1 and modified Fran) and the independent variables. A forward stepwise multiple linear regression analysis was performed and significant variables that survived the regression analysis were used to create a predictive model of HIFT performance. RESULTS: Absolute VO2 peak was a significant predictor of 19.1 performance, explaining 39% of its variance (adjusted R2 = 0.39, p = 0.002). For modified Fran, total strength was a significant predictor and explained 33% of the variance in performance (adjusted R2 = 0.33, p = 0.005). CONCLUSION: These results suggest, without any influence of HIFT familiarity or experience, that performance in these two HIFT workouts could be predicted by distinct laboratory-based measurements of fitness.

Impacts of phosphorus loads on the water quality and the proliferation of harmful cyanobacteria in Foum-Gleita Reservoir (Mauritania)

Excess phosphorus and nitrogen inputs into freshwater ecosystems is one of the main causes of expansion of harmful cyanobacterial blooms worldwide. This work was conducted to study the impacts of phosphorus leaching from the exploitation of phosphate mines present in the watershed of Foum-Gleita Reservoir (Mauritania) on the water quality and its major contribution to the proliferation of harmful cyanobacteria throughout the year. The physicochemical parameters, the occurrence and abundance of phytoplankton (including cyanobacteria), and the microcystins concentration were monitored monthly from September 2017 to August 2018. The relationships between limnological and biological variables were explored by using Pearson's correlation and forward stepwise multiple linear regression (MLR) analysis. Microcystins were detected by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Our results showed that this reservoir can be classified as hypereutrophic throughout the year and that Microcystis aeruginosa (M. aeruginosa) and Dolichospermum flos-aquae (D. flos-aquae) were dominant species during the rainy season (July-September), and only the congener microcystin-LR (MC-LR) was detected with a peak at 3.55 µg L−1. Pearson's correlation and MLR analysis showed that water temperature pH, phosphorus, nitrogen, and iron concentrations were the most important variables accounting for M. aeruginosa and D. flos-aquae abundance and MC-LR concentration. Our study provides new insight into the effects of moderate nitrogen concentrations on phytoplankton community composition with dominance of the cyanobacteria phylum in phosphorus-rich freshwater ecosystems.

The Relationship between CrossFit® Performance and Laboratory-Based Measurements of Fitness.

To date, research has examined the physiological determinants of performance in standardized CrossFit® (CF) workouts but not without the influence of CF familiarity. Therefore, the purpose of this present study was to examine the predictive value of aerobic fitness, body composition, and total body strength on performance of two standardized CF workouts in CF-naïve participants. Twenty-two recreationally trained individuals (males = 13, females = 9) underwent assessments of peak oxygen consumption (VO2 peak), ventilatory thresholds, body composition, and one repetition maximum tests for the back squat, deadlift, and overhead press in which the sum equaled the CF Total. Participants also performed two CF workouts: a scaled version of the CF Open workout 19.1 and a modified version of the CF Benchmark workout Fran to determine scores based on total repetitions completed and time-to-completion, respectively. Simple Pearson’s r correlations were used to determine the relationships between CF performance variables (19.1 and modified Fran) and the independent variables. A forward stepwise multiple linear regression analysis was performed and significant variables that survived the regression analysis were used to create a predictive model of CF performance. Absolute VO2 peak was a significant predictor of 19.1 performance, explaining 39% of its variance (adjusted R2 = 0.39, p = 0.002). For modified Fran, CF Total was a significant predictor and explained 33% of the variance in performance (adjusted R2 = 0.33, p = 0.005). These results suggest, without any influence of CF familiarity or experience, that performance in these two CF workouts could be predicted by distinct laboratory-based measurements of fitness.

3-Dimensional objective aesthetic evaluation to replace panel assessment after breast-conserving treatment

BackgroundTwo-thirds of patients with early breast cancer undergo breast-conserving treatment (BCT). Aesthetic outcome is important and has long term implications for psychosocial wellbeing. The aesthetic goal of BCT is symmetry for which there is no gold-standard measure. Panel scoring is the most widely adopted assessment but has well-described limitations. This paper describes a model to objectively report aesthetic outcome using measures derived from 3-dimensional surface images (3D-SI).MethodObjective measures and panel assessment were undertaken independently for 3D-SI of women who underwent BCT 1–5 years previously. Univariate analysis was used to test for association between measures and panel score. A forward stepwise multiple linear regression model was fitted to identify 3D measurements that jointly predicted the mean panel score. The fitted model coefficients were used to predict mean panel scores for an independent validation set then compared to the mean observed panel score.ResultsVery good intra-panel reliability was observed for the training and validation sets (wκ = 0.87, wκ = 0.84). Six 3D-measures were used in the multivariate model. There was a good correlation between the predicted and mean observed panel score in the training (n = 190) and validation (n = 100) sets (r = 0.68, r = 0.65). The 3D model tended to predict scores towards the median. The model was calibrated which improved the distribution of predicted scores.ConclusionA six-variable objective aesthetic outcome model for BCT has been described and validated. This can predict and could replace panel assessment, facilitating the independent and unbiased evaluation of aesthetic outcome to communicate and compare results, benchmark practice, and raise standards.

In vivo measures of anterior scleral resistance in humans with rebound tonometry.

To measure regional variations in anterior scleral resistance (ASR) using a ballistic rebound tonometer (RBT) and examine whether the variations are significantly affected by ethnicity and refractive error (RE). ASR was measured using a RBT (iCare TA01) following calibration against the biomechanical properties of agarose biogels. Eight scleral regions (nasal, temporal, superior, inferior, inferior-nasal, inferior-temporal, superior-nasal and superior-temporal) were measured at locations 4mm from the limbus. Subjects were 130 young adults comprising three ethnic groups whose RE distributions [MSE (D) ± S.D.] incorporated individuals categorised as without-myopia (NM; MSE≥-0.50) and with-myopia (WM; MSE<-0.50); British-White (BW): 26 NM+0.52±1.15D; 22 WM -3.83±2.89D]; British-South-Asian (BSA): [9 NM+0.49±1.06D; 11 WM -5.07±3.76D; Hong-Kong-Chinese (HKC): [11 NM+0.39±0.66D; 49 WM -4.46±2.70D]. Biometric data were compiled using cycloplegic open-field autorefraction and the Zeiss IOLMaster. Two- and three-way repeated measures analysis of variances (anovas) tested regional differences for RBT values across both refractive status and ethnicity whilst stepwise forward multiple linear regression was used as an exploratory test. Significant regional variations in ASR were identified for the BW, BSA and HKC (p<0.001) individuals; superior-temporal region showed the lowest levels of resistance whilst the inferior-nasal region the highest. Compared to the BW and BSA groups, the HKC subjects displayed a significant increase in mean resistance for each respective region (p<0.001). With the exception of the inferior region, ethnicity was found to be the chief predictor for variation in the scleral RBT values for all other regions. Mean RE group differences were insignificant. The novel application of RBT to the anterior sclera confirm regional variation in ASR. Greater ASR amongst the HKC group than the BW and BSA individuals suggests that ethnic differences in anterior scleral biomechanics may exist.

An easy method for monitoring patients with pulmonary Hypertension: P-wave dispersion.

Pulmonary arterial hypertension (PAH) is a haemodynamic and pathophysiological condition with restricted flow through the pulmonary arterial circulation. In pulmonary hypertension, right ventricular hypertrophy and diastolic dysfunction can lead to an increase in atrial strain, fibrosis and dilation, which cause inhomogeneous atrial conduction. Interlead variation in P-wave duration is called P-wave dispersion (PwD), which is an electrocardiographic parameter that can be used to predict atrial arrhythmias. Our aim was to investigate the relationship between PwD, functional capacity, and invasive and non-invasive haemodynamic parameters of patients diagnosed with PAH. Between 2015 and 2017 we enrolled 33 patients admitted to our in-patient clinic and diagnosed with PAH, and 32 healthy individuals for the control group. Details of these patients at the time of diagnosis were analysed, including gender, age, physical examination, electrocardiogram (ECG), echocardiography, six-minute walk test distance (6MWD), haemodynamic parameters and blood tests for biochemical markers that are correlated with clinical severity. Statistical analyses were performed using SPSS version 20.0 (SPSS Inc, Chicago, Illinois, USA). Statistical significance was taken as p < 0.05. In the forward stepwise multiple linear regression analysis, PwD and mean pulmonary artery pressure determined by right heart catheterisation were independently related to the functional capacity tested by the 6MWD (p < 0.02 and p < 0.01, respectively). PwD can easily be calculated from a surface ECG to indirectly estimate the functional status and prognosis of the patient with PAH.