Modern multiligament knee injury surgical reconstruction techniques can achieve excellent knee function and patient satisfaction, with low complication rates.

PURPOSE: To report on the recovery of strength and functional capacity symmetry following multiligament knee surgical reconstruction (MLKR), as well as the capacity of athletes to return to sport. METHODS: This prospective cohort study recruited 47 patients undergoing MLKR between February 2018 and July 2021. Forty patients had full outcome assessment postoperatively at 6, 12 and 24 months and were included in the analysis, 75% were knee dislocation one injuries and 60% were injured playing sport. Patient-reported outcome measures (PROMs) assessed included the International Knee Documentation Committee score, the Knee Outcome Survey, the Lysholm Knee Score and the Tegner Activity Scale (TAS). Patient satisfaction was also assessed. Objective assessment included assessment of active knee flexion and extension range of motion (ROM), the single (single horizontal hop for distance [SHD]) and triple (triple horizontal hop for distance [THD]) hop tests for distance and peak isokinetic knee flexor/extensor torque. RESULTS: All PROMs significantly improved (p < 0.001) from presurgery to 24 months postsurgery. At 24 months, 70% of patients were satisfied with their sports participation. Active knee flexion (p < 0.0001) and extension (p < 0.0001) ROM significantly improved over time, as did the limb symmetry indices (LSIs) for the SHD (p < 0.0001), THD (p < 0.0001), peak knee extensor (p < 0.0001) and flexor (p = 0.012) torque. While LSIs for the SHD, THD and knee flexor strength tended to plateau by 12 months, knee extensor strength continued to improve from 12 to 24 months. CONCLUSIONS: The majority of patients undergoing modern MLKR surgical techniques and rehabilitation can achieve excellent knee function, with low complication rates. LEVEL OF EVIDENCE: Level IV.

Patients undergoing multiligament knee reconstruction injured during pivoting sports demonstrate similar clinical, functional and return to sport outcomes by 2 years compared with those undergoing anterior cruciate ligament reconstruction.

PURPOSE: This study investigates the clinical and activity-based outcomes after anterior cruciate ligament reconstruction (ACLR) versus multiligamentous knee reconstruction (MLKR) following a pivoting sports injury. METHODS: Fifty MLKR patients were included, of which 20 (40%) were injured during pivoting sports. A further 50 patients undergoing ACLR following an injury during pivoting sports were consecutively recruited for comparison. Patients were assessed before the surgery and at 6-, 12- and 24 months with patient-reported outcome measures (PROMs) including the International Knee Documentation Committee (IKDC) form, Tegner activity scale (TAS) and anterior cruciate ligament return to sport after injury (ACL-RSI) score. Knee movement, the single (SHD) and triple (THD) hop tests for distance, and peak isokinetic knee extensor and flexor strength were assessed, with Limb Symmetry Indices (LSIs) calculated. Outcomes were compared across groups: (1) ACLR (n = 50), (2) MLKR (n = 50) and (3) MLKR due to pivoting sport injury (n = 20). RESULTS: IKDC, TAS and ACL-RSI scores remained lower (p < 0.05) in the full MLKR versus ACLR cohort at all timepoints. Comparing the ACLR and MLKR cohort that had injuries specifically during pivoting sports, the IKDC (p < 0.001) and TAS (p = 0.009) were higher in the ACLR group at 6 months, and the ACL-RSI was higher at 6 (p < 0.001) and 12 (p = 0.007) months, there were no further differences. Hop and knee extensor strength LSIs were lower (p < 0.05) in the full MLKR (versus ACLR) cohort at all timepoints (apart from the 24-month SHD LSI). However, the ACLR group only demonstrated greater LSIs than the pivoting sport MLKR for the SHD at 6 months (p < 0.001), and knee extensor strength at 6 (p < 0.001) and 12 (p < 0.001) months. CONCLUSIONS: While the recovery of patients undergoing MLKR due to a pivoting sports injury is delayed compared with their ACLR counterparts, the clinical outcome and activity profile are similar by 24 months. LEVEL OF EVIDENCE: Level IV.

Demographic Determinants of Residue Profiles of Fungicidal Compounds in Common Voles (Microtus arvalis) under Semi-Natural and Natural Conditions.

Environmental risks from plant protection products (PPPs) need to be assessed to ensure safe use. The risk assessments are generally carried out using the common vole as a focal species with conservative theoretical estimates of external exposure. These are then compared to dose-related toxicity endpoints established in toxicity studies, often with laboratory species. The aim of the present study was to determine the actual internal dosimetry of PPPs' active ingredients (AIs) in a population of common voles to provide the basis for informed higher tier risk assessment. As a proof of concept, two fungicidal AIs (fludioxonil and cyprodinil) were investigated using a range of application methodologies. Individuals were treated using oral gavage application (AI dose: 100/200 mg/kg) and fed treated grass (AI sprayed at 2 kg/ha) under laboratory, semi-natural, and natural conditions. Our results show that demographic factors play a significant role in the individual residue profile and that age structure is a key aspect that determines the overall exposure risk of a population. These results are consistent from laboratory to field conditions. Future approaches could establish dose-residue relationships that are reflective of natural food intake rates in wild common vole populations in the risk assessment of PPPs.

LXR signaling couples sterol metabolism to proliferation in the acquired immune response.

Cholesterol is essential for membrane synthesis; however, the mechanisms that link cellular lipid metabolism to proliferation are incompletely understood. We demonstrate here that cellular cholesterol levels in dividing T cells are maintained in part through reciprocal regulation of the LXR and SREBP transcriptional programs. T cell activation triggers induction of the oxysterol-metabolizing enzyme SULT2B1, consequent suppression of the LXR pathway for cholesterol transport, and promotion of the SREBP pathway for cholesterol synthesis. Ligation of LXR during T cell activation inhibits mitogen-driven expansion, whereas loss of LXRbeta confers a proliferative advantage. Inactivation of the sterol transporter ABCG1 uncouples LXR signaling from proliferation, directly linking sterol homeostasis to the antiproliferative action of LXR. Mice lacking LXRbeta exhibit lymphoid hyperplasia and enhanced responses to antigenic challenge, indicating that proper regulation of LXR-dependent sterol metabolism is important for immune responses. These results implicate LXR signaling in a metabolic checkpoint that modulates cell proliferation and immunity.

Good clinical scores, no evidence of excessive anterior tibial translation, a high return to sport rate and a low re-injury rate is observed following anterior cruciate ligament reconstruction using autologous hamstrings augmented with suture tape.

INTRODUCTION: Augmented anterior cruciate ligament reconstruction (ACLR) techniques have been proposed to reduce the high reported re-injury rates and low rates of return to sport (RTS). This study reports clinical outcomes, RTS and re-injury rates in patients undergoing ACLR using autologous hamstrings augmented with suture tape. MATERIALS AND METHODS: A total of 53 patients were prospectively recruited, undergoing ACLR using hamstrings with suture tape augmentation, combined with a structured rehabilitation programme. Outcomes were collected to 24 months, including patient-reported outcome measures (PROMs), KT-1000 measurements, peak isokinetic knee strength and a four hop test battery. Limb Symmetry Indices (LSIs) were calculated for performance measures, whilst RTS rates, re-tears and re-operations were presented. RESULTS: There were no significant side-to-side differences in anterior tibial translation between the operated and non-operated knees at 6 months (p = 0.433), with no increase (p = 0.841) in side-to-side anterior tibial translation from 6 to 24 months. At 24 months, 98.0% of patients demonstrated normal (< 3 mm) or near normal (3-5 mm) side-to-side differences. LSIs for peak knee extensor torque (p < 0.0001) and the single (p = 0.001), triple (p = 0.001) and triple crossover (p < 0.0001) hop tests for distance significantly improved. All PROMs significantly improved (p < 0.0001), with 70.2% and 85.7% of patients actively participating in pivoting sports at 12 and 24 months, respectively. Three patients underwent secondary procedures for meniscal symptoms. One patient suffered an ACL re-tear (17 months), with no further ipsilateral or contralateral injuries. CONCLUSION: ACLR with suture tape augmentation demonstrated no evidence of excessive anterior tibial translation, high-scoring PROMs, sound performance scores, a high rate of RTS and low re-injury rate.

Transcription Factor MAFF (MAF Basic Leucine Zipper Transcription Factor F) Regulates an Atherosclerosis Relevant Network Connecting Inflammation and Cholesterol Metabolism.

BACKGROUND: Coronary artery disease (CAD) is a multifactorial condition with both genetic and exogenous causes. The contribution of tissue-specific functional networks to the development of atherosclerosis remains largely unclear. The aim of this study was to identify and characterize central regulators and networks leading to atherosclerosis. METHODS: Based on several hundred genes known to affect atherosclerosis risk in mouse (as demonstrated in knockout models) and human (as shown by genome-wide association studies), liver gene regulatory networks were modeled. The hierarchical order and regulatory directions of genes within the network were based on Bayesian prediction models, as well as experimental studies including chromatin immunoprecipitation DNA-sequencing, chromatin immunoprecipitation mass spectrometry, overexpression, small interfering RNA knockdown in mouse and human liver cells, and knockout mouse experiments. Bioinformatics and correlation analyses were used to clarify associations between central genes and CAD phenotypes in both human and mouse. RESULTS: The transcription factor MAFF (MAF basic leucine zipper transcription factor F) interacted as a key driver of a liver network with 3 human genes at CAD genome-wide association studies loci and 11 atherosclerotic murine genes. Most importantly, expression levels of the low-density lipoprotein receptor (LDLR) gene correlated with MAFF in 600 CAD patients undergoing bypass surgery (STARNET [Stockholm-Tartu Atherosclerosis Reverse Network Engineering Task]) and a hybrid mouse diversity panel involving 105 different inbred mouse strains. Molecular mechanisms of MAFF were tested in noninflammatory conditions and showed positive correlation between MAFF and LDLR in vitro and in vivo. Interestingly, after lipopolysaccharide stimulation (inflammatory conditions), an inverse correlation between MAFF and LDLR in vitro and in vivo was observed. Chromatin immunoprecipitation mass spectrometry revealed that the human CAD genome-wide association studies candidate BACH1 (BTB domain and CNC homolog 1) assists MAFF in the presence of lipopolysaccharide stimulation with respective heterodimers binding at the MAF recognition element of the LDLR promoter to transcriptionally downregulate LDLR expression. CONCLUSIONS: The transcription factor MAFF was identified as a novel central regulator of an atherosclerosis/CAD-relevant liver network. MAFF triggered context-specific expression of LDLR and other genes known to affect CAD risk. Our results suggest that MAFF is a missing link between inflammation, lipid and lipoprotein metabolism, and a possible treatment target.

A Four Carbon Organonitrate as a Significant Product of Secondary Isoprene Chemistry.

Oxidation of isoprene by nitrate radicals (NO3) or by hydroxyl radicals (OH) under high NOx conditions forms a substantial amount of organonitrates (ONs). ONs impact NOx concentrations and consequently ozone formation while also contributing to secondary organic aerosol. Here we show that the ONs with the chemical formula C4H7NO5 are a significant fraction of isoprene-derived ONs, based on chamber experiments and ambient measurements from different sites around the globe. From chamber experiments we found that C4H7NO5 isomers contribute 5%-17% of all measured ONs formed during nighttime and constitute more than 40% of the measured ONs after further daytime oxidation. In ambient measurements C4H7NO5 isomers usually dominate both nighttime and daytime, implying a long residence time compared to C5 ONs which are removed more rapidly. We propose potential nighttime sources and secondary formation pathways, and test them using a box model with an updated isoprene oxidation scheme.

Effectiveness of early versus delayed rehabilitation following total shoulder replacement: A systematic review.

OBJECTIVE: To investigate the effectiveness of early versus delayed rehabilitation following total shoulder replacement. DESIGN: Intervention systematic review with narrative synthesis. LITERATURE SEARCH: MEDLINE, EMBASE, CINAHL, Scopus and the Cochrane Library were searched from inception to the 29th of July 2021. STUDY SELECTION CRITERIA: Randomised controlled trials comparing early versus delayed rehabilitation following primary anatomic, primary reverse, or revision total shoulder replacement. DATA SYNTHESIS: A revised Cochrane risk of bias assessment tool for randomised controlled trials was used, as well as the Grading of Recommendations Assessment, Development and Evaluation approach to evaluate the quality of evidence. A narrative synthesis was undertaken. RESULTS: Three eligible randomised controlled trials (n = 230) were included. There was very low-quality evidence of no statistically significant difference (P > 0.05) in pain, shoulder function, health-related quality of life or lesser tuberosity osteotomy healing at 12 months between early or delayed rehabilitation. There was conflicting and very low-quality evidence of a difference between the effect of early and delayed rehabilitation on shoulder range of movement. There was limited, very low-quality evidence of statistically significantly improved pain and function (P < 0.05) in the early post-operative period with early rehabilitation following anatomic total shoulder replacement. CONCLUSIONS: No differences were seen in patient-reported or clinician-reported outcomes at 12 months post-surgery between early and delayed rehabilitation following total shoulder replacement. There is very low-quality evidence that early rehabilitation may improve shoulder pain and function in the early post-operative phase following anatomic total shoulder replacement.

Superalkali-Alkalide Interactions and Ion Pairing in Low-Polarity Solvents.

The nature of anionic alkali metals in solution is traditionally thought to be "gaslike" and unperturbed. In contrast to this noninteracting picture, we present experimental and computational data herein that support ion pairing in alkalide solutions. Concentration dependent ionic conductivity, dielectric spectroscopy, and neutron scattering results are consistent with the presence of superalkali-alkalide ion pairs in solution, whose stability and properties have been further investigated by DFT calculations. Our temperature dependent alkali metal NMR measurements reveal that the dynamics of the alkalide species is both reversible and thermally activated suggesting a complicated exchange process for the ion paired species. The results of this study go beyond a picture of alkalides being a "gaslike" anion in solution and highlight the significance of the interaction of the alkalide with its complex countercation (superalkali).

Key Role of NO3 Radicals in the Production of Isoprene Nitrates and Nitrooxyorganosulfates in Beijing.

The formation of isoprene nitrates (IsN) can lead to significant secondary organic aerosol (SOA) production and they can act as reservoirs of atmospheric nitrogen oxides. In this work, we estimate the rate of production of IsN from the reactions of isoprene with OH and NO3 radicals during the summertime in Beijing. While OH dominates the loss of isoprene during the day, NO3 plays an increasingly important role in the production of IsN from the early afternoon onwards. Unusually low NO concentrations during the afternoon resulted in NO3 mixing ratios of ca. 2 pptv at approximately 15:00, which we estimate to account for around a third of the total IsN production in the gas phase. Heterogeneous uptake of IsN produces nitrooxyorganosulfates (NOS). Two mono-nitrated NOS were correlated with particulate sulfate concentrations and appear to be formed from sequential NO3 and OH oxidation. Di- and tri-nitrated isoprene-related NOS, formed from multiple NO3 oxidation steps, peaked during the night. This work highlights that NO3 chemistry can play a key role in driving biogenic-anthropogenic interactive chemistry in Beijing with respect to the formation of IsN during both the day and night.

The periodic law of the chemical elements: 'The new system of atomic weights which renders evident the analogies which exist between bodies' [1].

The historical roots, the discovery and the modern relevance of Dmitri Mendeleev's remarkable advance have been the subject of numerous scholarly works. Here, with a brief overview, we hope to provide a link into the contents of this special issue honouring the great scientist. Mendeleev's advance, announced in March 1869, as he put it in 1889, to the '…then youthful Russian Chemical Society…', first set out the very basis of the periodic law of the chemical elements, the natural relation between the properties of the elements and their atomic weights. This was, and still is, the centrepiece of a historical journey for chemistry to today's position as a pre-eminent science. This article is part of the theme issue 'Mendeleev and the periodic table'.

Metals and non-metals in the periodic table.

The demarcation of the chemical elements into metals and non-metals dates back to the dawn of Dmitri Mendeleev's construction of the periodic table; it still represents the cornerstone of our view of modern chemistry. In this contribution, a particular emphasis will be attached to the question 'Why do the chemical elements of the periodic table exist either as metals or non-metals under ambient conditions?' This is perhaps most apparent in the p-block of the periodic table where one sees an almost-diagonal line separating metals and non-metals. The first searching, quantum-mechanical considerations of this question were put forward by Hund in 1934. Interestingly, the very first discussion of the problem-in fact, a pre-quantum-mechanical approach-was made earlier, by Goldhammer in 1913 and Herzfeld in 1927. Their simple rationalization, in terms of atomic properties which confer metallic or non-metallic status to elements across the periodic table, leads to what is commonly called the Goldhammer-Herzfeld criterion for metallization. For a variety of undoubtedly complex reasons, the Goldhammer-Herzfeld theory lay dormant for close to half a century. However, since that time the criterion has been repeatedly applied, with great success, to many systems and materials exhibiting non-metal to metal transitions in order to predict, and understand, the precise conditions for metallization. Here, we review the application of Goldhammer-Herzfeld theory to the question of the metallic versus non-metallic status of chemical elements within the periodic system. A link between that theory and the work of Sir Nevill Mott on the metal-non-metal transition is also highlighted. The application of the 'simple', but highly effective Goldhammer-Herzfeld and Mott criteria, reveal when a chemical element of the periodic table will behave as a metal, and when it will behave as a non-metal. The success of these different, but converging approaches, lends weight to the idea of a simple, universal criterion for rationalizing the instantly-recognizable structure of the periodic table where …the metals are here, the non-metals are there … The challenge of the metallic and non-metallic states of oxides is also briefly introduced. This article is part of the theme issue 'Mendeleev and the periodic table'.

High winter ozone pollution from carbonyl photolysis in an oil and gas basin.

The United States is now experiencing the most rapid expansion in oil and gas production in four decades, owing in large part to implementation of new extraction technologies such as horizontal drilling combined with hydraulic fracturing. The environmental impacts of this development, from its effect on water quality to the influence of increased methane leakage on climate, have been a matter of intense debate. Air quality impacts are associated with emissions of nitrogen oxides (NOx = NO + NO2) and volatile organic compounds (VOCs), whose photochemistry leads to production of ozone, a secondary pollutant with negative health effects. Recent observations in oil- and gas-producing basins in the western United States have identified ozone mixing ratios well in excess of present air quality standards, but only during winter. Understanding winter ozone production in these regions is scientifically challenging. It occurs during cold periods of snow cover when meteorological inversions concentrate air pollutants from oil and gas activities, but when solar irradiance and absolute humidity, which are both required to initiate conventional photochemistry essential for ozone production, are at a minimum. Here, using data from a remote location in the oil and gas basin of northeastern Utah and a box model, we provide a quantitative assessment of the photochemistry that leads to these extreme winter ozone pollution events, and identify key factors that control ozone production in this unique environment. We find that ozone production occurs at lower NOx and much larger VOC concentrations than does its summertime urban counterpart, leading to carbonyl (oxygenated VOCs with a C = O moiety) photolysis as a dominant oxidant source. Extreme VOC concentrations optimize the ozone production efficiency of NOx. There is considerable potential for global growth in oil and gas extraction from shale. This analysis could help inform strategies to monitor and mitigate air quality impacts and provide broader insight into the response of winter ozone to primary pollutants.

Accelerometry evaluation of shoulder movement and its association with patient-reported and clinical outcomes following reverse total shoulder arthroplasty.

BACKGROUND: Accelerometers provide a new method to objectively measure recovery of movement and physical activity in patients following reverse total shoulder arthroplasty (RTSA) and may overcome common limitations associated with patient-reported outcome measures (PROMs). The aim of this study was to assess changes in upper limb movement using accelerometers following RTSA and investigate their association with other clinical outcome measures. METHODS: Thirty-six patients who underwent RTSA wore accelerometers on both wrists and arms for 3 days at 3, 6, and 12 months postsurgery. PROMs (Constant score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, visual analog scale for pain, Single Assessment Numerical Evaluation, Shoulder Activity Level) and isometric shoulder strength were also assessed. Accelerometer outcomes were calculated to quantify counts of forearm and arm activity and the contribution of both arms to activity (limb symmetry and magnitude ratio). Changes and differences in all clinical measures and objective movement measures were evaluated with within-subjects analysis of variance. Correlations between limb activity and other clinical measures were investigated using Spearman correlation coefficients. RESULTS: Objective movement of the operated arm increased from 3-6 months postsurgery (P = .004), but not from 6-12 months (P = .240). Limb asymmetries were observed at 3 and 6 months and improved by 12 months postsurgery. No associations were demonstrated between PROMs and objective upper limb movement at 12 months postsurgery. DISCUSSION: Despite early recovery of function and pain relief assessed by PROMs, objective movement using accelerometers showed delayed recovery of the operated arm postoperatively, before normalizing by 12 months postsurgery. Accelerometers provide a unique insight into functional recovery following RTSA.

A conceptual framework to untangle the concept of urban ecosystem services.

Urban ecosystem service (UES) is becoming an influential concept to guide the planning, design, and management of urban landscapes towards urban sustainability. However, its use is hindered by definitional ambiguity, and the conceptual bases underpinning its application remain weak. This is exemplified by two different but equally valid interpretations of UES: "urban ecosystem services", referring to ecosystem services from analogs of natural and semi-natural ecosystems within urban boundaries, and "urban ecosystem services", a much broader term that includes the former group as well as urban services in a city. While we recognize that a single definition of UES is not possible nor necessary as its application is context-dependent, it is nevertheless useful to clarify the relationships between these interpretations to promote consistent use, and importantly, explore how a broader interpretation of UES might advance its applications in areas that have been neglected. We developed a conceptual framework that links UES to natural and human-derived capital to explain the relationships between the dual meanings of UES and proposed three normative propositions to guide its application: (1) integrate holistically multiple components of natural capital to provide UES, (2) reduce dependence on non-renewable abiotic resources and human-derived capital, and (3) enhance UES through technology. The framework we developed helps to resolve the current ambiguity in the meanings of UES, highlights the need to recognise neglected aspects of natural capital important for UES, and can be used to clarify relationships with related concepts conveying dependence of human well-being on nature.

Current Perspectives of the Australian Knee Society on Rehabilitation and Return to Sport After Anterior Cruciate Ligament Reconstruction.

CONTEXT: The importance of rehabilitation and evaluation prior to return to sport (RTS) in patients undergoing anterior cruciate ligament reconstruction has been reported. OBJECTIVE: This study sought to investigate current perspectives of Australian orthopedic surgeons on rehabilitation and RTS evaluation. DESIGN: Survey. PARTICIPANTS: Members of the Australian Knee Society. MAIN OUTCOME MEASURES: A 14-question survey was disseminated to Australian Knee Society members (orthopedic surgeons) to investigate (1) preferred graft choice, (2) estimated retear rate, (3) importance of preoperative and postoperative rehabilitation, and (4) preferred timing of RTS and evaluation prior to RTS discharge. RESULTS: Of all 85 Australian Knee Society members contacted, 86% (n = 73) responded. Overall, 66 respondents (90.4%) preferentially used hamstring tendon autografts. All surgeons estimated their retear rate to be ≤15%, with 31 (42.5%) <5%. Twenty-eight surgeons (38.4%) reported no benefit in preoperative rehabilitation. The majority of surgeons (82.2%-94.5%) reported that postoperative rehabilitation was important within various periods throughout the postoperative timeline. Most surgeons did not permit RTS until ≥9 months (n = 56, 76.7%), with 17 (23.3%) allowing RTS between 6 and 9 months. The most highly reported considerations for RTS clearance were time (90.4%), functional capacity (90.4%), and strength (78.1%). Most commonly, knee strength and/or function was assessed via referral to a preferred rehabilitation specialist (50.7%) or with the surgeon at their practice (11.0%). CONCLUSIONS: This survey revealed variation in beliefs and practices surrounding rehabilitation and RTS evaluation. This is despite the current evidence demonstrating the benefit of preoperative and postoperative rehabilitation, as well as the emerging potential of RTS assessments consisting of strength and functional measures to reduce reinjury rates.

Trait differentiation and adaptation of plants along elevation gradients.

Studies of genetic adaptation in plant populations along elevation gradients in mountains have a long history, but there has until now been neither a synthesis of how frequently plant populations exhibit adaptation to elevation nor an evaluation of how consistent underlying trait differences across species are. We reviewed studies of adaptation along elevation gradients (i) from a meta-analysis of phenotypic differentiation of three traits (height, biomass and phenology) from plants growing in 70 common garden experiments; (ii) by testing elevation adaptation using three fitness proxies (survival, reproductive output and biomass) from 14 reciprocal transplant experiments; (iii) by qualitatively assessing information at the molecular level, from 10 genomewide surveys and candidate gene approaches. We found that plants originating from high elevations were generally shorter and produced less biomass, but phenology did not vary consistently. We found significant evidence for elevation adaptation in terms of survival and biomass, but not for reproductive output. Variation in phenotypic and fitness responses to elevation across species was not related to life history traits or to environmental conditions. Molecular studies, which have focussed mainly on loci related to plant physiology and phenology, also provide evidence for adaptation along elevation gradients. Together, these studies indicate that genetically based trait differentiation and adaptation to elevation are widespread in plants. We conclude that a better understanding of the mechanisms underlying adaptation, not only to elevation but also to environmental change, will require more studies combining the ecological and molecular approaches.

Apoptotic cells promote their own clearance and immune tolerance through activation of the nuclear receptor LXR.

Effective clearance of apoptotic cells by macrophages is essential for immune homeostasis. The transcriptional pathways that allow macrophages to sense and respond to apoptotic cells are poorly defined. We found that liver X receptor (LXR) signaling was important for both apoptotic cell clearance and the maintenance of immune tolerance. Apoptotic cell engulfment activated LXR and thereby induced the expression of Mer, a receptor tyrosine kinase critical for phagocytosis. LXR-deficient macrophages exhibited a selective defect in phagocytosis of apoptotic cells and an aberrant proinflammatory response to them. As a consequence of these defects, mice lacking LXRs manifested a breakdown in self-tolerance and developed autoantibodies and autoimmune glomerulonephritis. Treatment with an LXR agonist ameliorated disease progression in a mouse model of lupus-like autoimmunity. Thus, activation of LXR by apoptotic cells engages a virtuous cycle that promotes their own clearance and couples engulfment to the suppression of inflammatory pathways.

Validation of the Schieman and Young measurement scales for work contact, work-family conflict, working conditions, psychological distress and sleep problems in construction industry professionals.

BACKGROUND: This study examined the construct validity and internal consistency of modified versions of the job autonomy and control, job pressure, work contact, work-family conflict, psychological distress, and sleep problems scales developed by Schieman and Young (2013) among construction professionals through confirmatory factor analysis and tests of internal consistency. METHODS: Using a cross-sectional design, survey data were collected from 942 South African construction professionals, of which 630 responses were considered for analysis. Confirmatory factor analysis was used to examine construct validity. Cronbach's coefficient alpha was used to determine the internal consistency, and convergent validity was tested using correlation analysis. RESULTS: The final CFA indicated very good model fit to the data (χ2 /df ratio = 2.11, IFI = .95, CFI = .95, RMSEA = .06, and Hoelter (95%) = 176). The scales demonstrated satisfactory internal consistency: .82; .91; .83; .90; .90; and .73, respectively. Convergent validity was largely demonstrated with respect to direction of association, but not in relation to magnitude. A limitation of the validation study was the lack of available data for a more robust examination of reliability beyond internal consistency, such as test-retest. CONCLUSIONS: The six scales developed by Schieman and Young (2013) hold promise as measures of work contact, work-family conflict, psychological distress, and sleep problems in relation to working conditions of construction professionals.