The Influence of Trunk Flexion during Stand-to-Sit on Knee Extensor Eccentric Control and the Relationship Between Eccentric Control and Postural Stability

Stand-to-sit (StandTS) is an important functional activity that is done daily. During StandTS, knee extensor eccentric control plays a key role in decelerating the falling momentum for a stable and safe landing. The degree of trunk flexion is an important biomechanics factor to control the vertical downward acceleration of center of mass (CoM) during StandTS. This affects body weight loading on the knee extensors while they are eccentrically lengthening. Thus, manipulation of StandTS trunk flexion angle can modify the knee extensor eccentric control and StandTS landing balance (postural stability). However, the influence of trunk flexion on knee extensor eccentric control and the relationship between knee extensor eccentric control and postural stability during StandTS remains unknown. PURPOSE: To examine the effects of trunk flexion on knee extensor eccentric control and to determine the relationship between knee extensor eccentric control and postural stability during StandTS. METHODS: 9 healthy younger adults participated in this study (mean age = 21.2 ± 2.9 years). Participants maintained an upright standing position with the feet shoulder-width apart and placed their feet in a self-selected parallel foot position with feet on a force plate. All participants performed a StandTS action after a visual light cue was turned on. They repeated this task for a total of 20 trials, adjusting their trunk flexion angle each time. There were five trials for each of four different maximal trunk flexion angles (0°, 20°, 40°, 60°). Participants crossed their arms over their chest during the StandTS task and sat down on an armless, backless, height adjustable chair. Outcome measures include 1) Vastus Lateralis (VL) (the knee extensor) eccentric electromyography (EMG) burst duration 2) knee joint eccentric work (negative work to resist body weight against gravity) and 3) postural sway (standard deviation of CoM acceleration (SDCoMAccel)) in the anterior-posterior (AP) and medio-lateral (ML) directions during StandTS. One-way multivariate analysis (MANOVA) was used for each variable with Tukey’s post hoc test to correct for multiple comparisons. A Pearson’s correlation was used to examine the correlation between eccentric control (EMG burst duration and eccentric work) and postural sway. RESULTS: There was a main effect of trunk flexion angle on knee extensor eccentric control and postural sway. 60° trunk flexion required greater eccentric control than 0° (EMG burst duration, p = 0.02, knee eccentric work, p= 0.01) and 20° (EMG burst duration, p = 0.01, knee eccentric work, p= 0.02). SDCoMAccel (postural sway) in the ML was smaller for 40° (p = 0.02) and 60° (p = 0.01) trunk flexion compared to 0° trunk flexion. In addition, there was a negative correlation between VL eccentric EMG burst duration and ML SDCoMAccel (postural sway) (r = – 0.30, p =0.04). CONCLUSION: Greater trunk flexion during StandTS required increased eccentric control at the knee joint. Increased knee extensor eccentric control has contributed to improved postural stability during StandTS. Our findings demonstrated the importance of trunk flexion and knee extensor eccentric control to maintain postural stability during StandTS

Microstructural Changes Induced by CO₂ Exposure in Alkali-Activated Slag/Metakaolin Pastes

The structural changes induced by accelerated carbonation in alkali-activated slag/metakaolin (MK) cements were determined. The specimens were carbonated for 540 h in an environmental chamber with a CO₂ concentration of 1.0 ± 0.2%, a temperature of 20 ± 2°C, and relative humidity of 65 ± 5%. Accelerated carbonation led to decalcification of the main binding phase of these cements, which is an aluminum substituted calcium silicate hydrate (C-(N-)A-S-H) type gel, and the consequent formation of calcium carbonate. The sodium-rich carbonates trona (Na₂CO₃·NaHCO₃·2H₂O) and gaylussite (Na₂Ca(CO₃)₂·5H₂O) were identified in cements containing up to 10 wt.% MK as carbonation products. The formation of these carbonates is mainly associated with the chemical reaction between the CO₂ and the free alkalis present in the pore solution. The structure of the carbonated cements is dominated by an aluminosilicate hydrate (N-A-S-H) type gel, independent of the MK content. The N-A-S-H type gels identified are likely to be derived both from the activation reaction of the MK, forming a low-calcium gel product that does not seem to undergo structural changes upon CO₂ exposure, and the decalcification of C-(N-)A-S-H type gel. The carbonated pastes present a highly porous microstructure, more notable as the content of MK content in the cement increases, which might have a negative impact on the durability of these materials in service

Circulating microRNAs in sera correlate with soluble biomarkers of immune activation but do not predict mortality in ART treated individuals with HIV-1 infection: A case control study

Introduction: The use of anti-retroviral therapy (ART) has dramatically reduced HIV-1 associated morbidity and mortality. However, HIV-1 infected individuals have increased rates of morbidity and mortality compared to the non-HIV-1 infected population and this appears to be related to end-organ diseases collectively referred to as Serious Non-AIDS Events (SNAEs). Circulating miRNAs are reported as promising biomarkers for a number of human disease conditions including those that constitute SNAEs. Our study sought to investigate the potential of selected miRNAs in predicting mortality in HIV-1 infected ART treated individuals. Materials and Methods: A set of miRNAs was chosen based on published associations with human disease conditions that constitute SNAEs. This case: control study compared 126 cases (individuals who died whilst on therapy), and 247 matched controls (individuals who remained alive). Cases and controls were ART treated participants of two pivotal HIV-1 trials. The relative abundance of each miRNA in serum was measured, by RTqPCR. Associations with mortality (all-cause, cardiovascular and malignancy) were assessed by logistic regression analysis. Correlations between miRNAs and CD4+ T cell count, hs-CRP, IL-6 and D-dimer were also assessed. Results: None of the selected miRNAs was associated with all-cause, cardiovascular or malignancy mortality. The levels of three miRNAs (miRs -21, -122 and -200a) correlated with IL-6 while miR-21 also correlated with D-dimer. Additionally, the abundance of miRs -31, -150 and -223, correlated with baseline CD4+ T cell count while the same three miRNAs plus miR- 145 correlated with nadir CD4+ T cell count. Discussion: No associations with mortality were found with any circulating miRNA studied. These results cast doubt onto the effectiveness of circulating miRNA as early predictors of mortality or the major underlying diseases that contribute to mortality in participants treated for HIV-1 infection

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Practical guidelines for rigor and reproducibility in preclinical and clinical studies on cardioprotection

The potential for ischemic preconditioning to reduce infarct size was first recognized more than 30 years ago. Despite extension of the concept to ischemic postconditioning and remote ischemic conditioning and literally thousands of experimental studies in various species and models which identified a multitude of signaling steps, so far there is only a single and very recent study, which has unequivocally translated cardioprotection to improved clinical outcome as the primary endpoint in patients. Many potential reasons for this disappointing lack of clinical translation of cardioprotection have been proposed, including lack of rigor and reproducibility in preclinical studies, and poor design and conduct of clinical trials. There is, however, universal agreement that robust preclinical data are a mandatory prerequisite to initiate a meaningful clinical trial. In this context, it is disconcerting that the CAESAR consortium (Consortium for preclinicAl assESsment of cARdioprotective therapies) in a highly standardized multi-center approach of preclinical studies identified only ischemic preconditioning, but not nitrite or sildenafil, when given as adjunct to reperfusion, to reduce infarct size. However, ischemic preconditioning—due to its very nature—can only be used in elective interventions, and not in acute myocardial infarction. Therefore, better strategies to identify robust and reproducible strategies of cardioprotection, which can subsequently be tested in clinical trials must be developed. We refer to the recent guidelines for experimental models of myocardial ischemia and infarction, and aim to provide now practical guidelines to ensure rigor and reproducibility in preclinical and clinical studies on cardioprotection. In line with the above guideline, we define rigor as standardized state-of-the-art design, conduct and reporting of a study, which is then a prerequisite for reproducibility, i.e. replication of results by another laboratory when performing exactly the same experiment

Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study

Ristola M. on työryhmien DAD Study Grp ; Royal Free Hosp Clin Cohort ; INSIGHT Study Grp ; SMART Study Grp ; ESPRIT Study Grp jäsen.Background Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice. Methods and Findings A total of 17,954 HIV-positive individuals from the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study with >= 3 estimated glomerular filtration rate (eGFR) values after 1 January 2004 were included. Baseline was defined as the first eGFR > 60 ml/min/1.73 m2 after 1 January 2004; individuals with exposure to tenofovir, atazanavir, atazanavir/ritonavir, lopinavir/ritonavir, other boosted protease inhibitors before baseline were excluded. CKD was defined as confirmed (>3 mo apart) eGFR In the D:A:D study, 641 individuals developed CKD during 103,185 person-years of follow-up (PYFU; incidence 6.2/1,000 PYFU, 95% CI 5.7-6.7; median follow-up 6.1 y, range 0.3-9.1 y). Older age, intravenous drug use, hepatitis C coinfection, lower baseline eGFR, female gender, lower CD4 count nadir, hypertension, diabetes, and cardiovascular disease (CVD) predicted CKD. The adjusted incidence rate ratios of these nine categorical variables were scaled and summed to create the risk score. The median risk score at baseline was -2 (interquartile range -4 to 2). There was a 1: 393 chance of developing CKD in the next 5 y in the low risk group (risk score = 5, 505 events), respectively. Number needed to harm (NNTH) at 5 y when starting unboosted atazanavir or lopinavir/ritonavir among those with a low risk score was 1,702 (95% CI 1,166-3,367); NNTH was 202 (95% CI 159-278) and 21 (95% CI 19-23), respectively, for those with a medium and high risk score. NNTH was 739 (95% CI 506-1462), 88 (95% CI 69-121), and 9 (95% CI 8-10) for those with a low, medium, and high risk score, respectively, starting tenofovir, atazanavir/ritonavir, or another boosted protease inhibitor. The Royal Free Hospital Clinic Cohort included 2,548 individuals, of whom 94 individuals developed CKD (3.7%) during 18,376 PYFU (median follow-up 7.4 y, range 0.3-12.7 y). Of 2,013 individuals included from the SMART/ESPRIT control arms, 32 individuals developed CKD (1.6%) during 8,452 PYFU (median follow-up 4.1 y, range 0.6-8.1 y). External validation showed that the risk score predicted well in these cohorts. Limitations of this study included limited data on race and no information on proteinuria. Conclusions Both traditional and HIV-related risk factors were predictive of CKD. These factors were used to develop a risk score for CKD in HIV infection, externally validated, that has direct clinical relevance for patients and clinicians to weigh the benefits of certain antiretrovirals against the risk of CKD and to identify those at greatest risk of CKD.Peer reviewe

Combining the HYM (Healthy Young Men’s) Cohort Study and the TRUTH (A Trans Youth of Color Study): Protocol for an Expanded Mixed Methods Study Renewal

BackgroundAs we enter the fifth decade of the AIDS epidemic, health researchers and AIDS activists reflect both on the progress that has been made and the importance of continued prevention efforts for those most at risk. As HIV infection rates continue to fluctuate across communities, a trend has emerged with new HIV infections becoming increasingly concentrated—with cascading effects—among people aged <30 years, from marginalized racial and ethnic groups, and who are sexual or gender minorities. ObjectiveIn this paper, we discuss the renewal of the Healthy Young Men’s (HYM) Cohort Study and the addition of a subcohort—TRUTH: A Transgender Youth of Color Study. The overarching aim of our renewed study was to inform new intervention strategies; understand linkage to care; and examine changes over time with respect to minority-related stress and intersectional identities and their relationship with substance use, mental health, and HIV risk. Findings from this study will help to inform the development of new interventions designed to engage African American and Black and Latino young men who have sex with men (YMSM) and transgender and gender minority youth in the HIV prevention and care continua and to reduce risk by addressing pathways of minority-related stress and intersectional stigma. MethodsLongitudinal study (baseline and follow-up assessments every 6 months for a total of 8 waves of data collection) is ongoing with reconsented cohort from the last iteration of HYM Cohort Study. This study protocol includes self-report survey, collection of urine to assess recent use of illicit drugs, and collection of blood and rectal and throat swabs to test for current sexually transmitted infection and HIV infection. An additional sample of blood and plasma (10 mL for 4 aliquots and 1 pellet) is also collected and stored in the HYM Cohort Study biorepository for future studies. This mixed methods study design includes collection of triangulated analysis of quantitative, qualitative, and biological measures (ie, drug use, sexually transmitted infection and HIV testing, and adherence to antiretroviral therapy among participants who are HIV+) at baseline and every 6 months. ResultsAs of February 2022, participants from the past 4 years of the HYM Cohort Study and TRUTH: A Transgender Youth of Color Study Cohort have been reconsented and enrolled into the renewal period of longitudinal data collection, which is projected from summer of 2020 until summer of 2025. Recruitment is ongoing to reach our target enrollment goal of YMSM and transgender minority youth. ConclusionsThe findings from this study are being used to inform the development of new, and adaptation of existing, evidence-based HIV prevention interventions designed to engage populations of transgender and gender minority youth and YMSM in the HIV prevention and care continua. International Registered Report Identifier (IRRID)DERR1-10.2196/3923

A framework for contextualizing social‐ecological biases in contributory science data

Contributory science—including citizen and community science—allows scientists to leverage participant-generated data while providing an opportunity for engaging with local community members. Data yielded by participant-generated biodiversity platforms allow professional scientists to answer ecological and evolutionary questions across both geographic and temporal scales, which is incredibly valuable for conservation efforts. The data reported to contributory biodiversity platforms, such as eBird and iNaturalist, can be driven by social and ecological variables, leading to biased data. Though empirical work has highlighted the biases in contributory data, little work has articulated how biases arise in contributory data and the societal consequences of these biases. We present a conceptual framework illustrating how social and ecological variables create bias in contributory science data. In this framework, we present four filters—participation, detectability, sampling and preference—that ultimately shape the type and location of contributory biodiversity data. We leverage this framework to examine data from the largest contributory science platforms—eBird and iNaturalist—in St. Louis, Missouri, the United States, and discuss the potential consequences of biased data. Lastly, we conclude by providing several recommendations for researchers and institutions to move towards a more inclusive field. With these recommendations, we provide opportunities to ameliorate biases in contributory data and an opportunity to practice equitable biodiversity conservation. Read the free Plain Language Summary for this article on the Journal blog