A mathematical model of signalling molecule-mediated processes during regeneration of osteochondral defects after chondrocyte implantation.

Treating bone-cartilage defects is a fundamental clinical problem. The ability of damaged cartilage to self-repair is limited due to its avascularity. Left untreated, these defects can lead to osteoarthritis. Details of osteochondral defect repair are elusive, but animal models indicate healing occurs via an endochondral ossification-like process, similar to that in the growth plate. In the growth plate, the signalling molecules parathyroid hormone-related protein (PTHrP) and Indian Hedgehog (Ihh) form a feedback loop regulating chondrocyte hypertrophy, with Ihh inducing and PTHrP suppressing hypertrophy. To better understand this repair process and to explore the regulatory role of signalling molecules on the regeneration process, we formulate a reaction-diffusion mathematical model of osteochondral defect regeneration after chondrocyte implantation. The drivers of healing are assumed to be chondrocytes and osteoblasts, and their interaction via signalling molecules. We model cell proliferation, migration and chondrocyte hypertrophy, and matrix production and conversion, spatially and temporally. We further model nutrient and signalling molecule diffusion and their interaction with the cells. We consider the PTHrP-Ihh feedback loop as the backbone mechanisms but the model is flexible to incorporate extra signalling mechanisms if needed. Our mathematical model is able to represent repair of osteochondral defects, starting with cartilage formation throughout the defect. This is followed by chondrocyte hypertrophy, matrix calcification and bone formation deep inside the defect, while cartilage at the surface is maintained and eventually separated from the deeper bone by a thin layer of calcified cartilage. The complete process requires around 48 months. A key highlight of the model demonstrates that the PTHrP-Ihh loop alone is insufficient and an extra mechanism is required to initiate chondrocyte hypertrophy, represented by a critical cartilage density. A parameter sensitivity study reveals that the timing of the repair process crucially depends on parameters, such as the critical cartilage density, and those describing the actions of PTHrP to suppress hypertrophy, such as its diffusion coefficient, threshold concentration and degradation rate.

Midterm outcome of superior capsular reconstruction using doubled acellular human dermal allograft for irreparable rotator cuff tear.

BACKGROUND: Thicker (folded) facia lata autografts have been shown to be superior to thinner grafts and single-layered acellular human dermal (HD) allografts for superior capsular reconstruction (SCR) in biomechanical studies. The aim of this study was to evaluate the midterm clinical outcomes following SCR for irreparable supraspinatus tears using doubled (folded) HD allograft. METHODS: Thirty-two patients who had undergone SCR using doubled HD allograft between February 2012 and January 2020 were recruited in a continuous manner in this retrospective study. The inclusion criteria were SCR performed for irreparable supraspinatus tear and a minimum of 2 years' follow-up. The primary outcome measure was the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score. The secondary outcome measures were complications and revision surgery. A subgroup analysis was performed between patients who received a "standard" graft of mean 3-mm thickness or a "thick" graft of mean 4.4-mm thickness. RESULTS: One patient was lost to follow-up. A total of 31 patients (31 shoulder joints) were analyzed with a mean follow-up duration of 48 months (range, 25-96 months). Following surgery, there was significant improvement in the ASES score from 18.1 ± 14.3 (preoperative) to 76.3 ± 25.1 (postoperative) (P < .001), with a satisfactory clinical outcome obtained in 83.8% of the patients. In a subset of 8 patients completing 5 years' follow-up, the clinical improvements were sustained. The percentage of patients with a clinically successful outcome was higher among those with thick grafts compared to those with standard grafts, although this failed to reach statistical significance (94.4% vs. 69.2%, risk ratio 1.36, 95% confidence interval 0.93-1.99, P = .13). One patient within the standard group underwent revision surgery. CONCLUSION: SCR for irreparable rotator cuff tears with doubled HD allograft results in improved clinical outcomes and low reoperation at midterm follow-up duration.

Prdx4 limits caspase-1 activation and restricts inflammasome-mediated signaling by extracellular vesicles.

Inflammasomes are cytosolic protein complexes, which orchestrate the maturation of active IL-1ß by proteolytic cleavage via caspase-1. Although many principles of inflammasome activation have been described, mechanisms that limit inflammasome-dependent immune responses remain poorly defined. Here, we show that the thiol-specific peroxidase peroxiredoxin-4 (Prdx4) directly regulates IL-1ß generation by interfering with caspase-1 activity. We demonstrate that caspase-1 and Prdx4 form a redox-sensitive regulatory complex via caspase-1 cysteine 397 that leads to caspase-1 sequestration and inactivation. Mice lacking Prdx4 show an increased susceptibility to LPS-induced septic shock. This effect was phenocopied in mice carrying a conditional deletion of Prdx4 in the myeloid lineage (Prdx4-ΔLysMCre). Strikingly, we demonstrate that Prdx4 co-localizes with inflammasome components in extracellular vesicles (EVs) from inflammasome-activated macrophages. Purified EVs are able to transmit a robust IL-1ß-dependent inflammatory response in vitro and also in recipient mice in vivo. Loss of Prdx4 boosts the pro-inflammatory potential of EVs. These findings identify Prdx4 as a critical regulator of inflammasome activity and provide new insights into remote cell-to-cell communication function of inflammasomes via macrophage-derived EVs.

Adverse Events in Pediatric Critical Care Nonsurvivors With a Low Predicted Mortality Risk: A Multicenter Case Control Study.

OBJECTIVES: Some patients with a low predicted mortality risk in the PICU die. The contribution of adverse events to mortality in this group is unknown. The aim of this study was to estimate the occurrence of adverse events in low-risk nonsurvivors (LN), compared with low-risk survivors (LS) and high-risk PICU survivors and nonsurvivors, and the contribution of adverse events to mortality. DESIGN: Case control study. Admissions were selected from the national Dutch PICU registry, containing 53,789 PICU admissions between 2006 and 2017, in seven PICUs. PICU admissions were stratified into four groups, based on mortality risk (low/high) and outcome (death/survival). Random samples were selected from the four groups. Cases were "LN." Control groups were as follows: "LS," "high-risk nonsurvivors" (HN), and "high-risk survivors" (HS). Adverse events were identified using the validated trigger tool method. SETTING: Patient chart review study. PATIENTS: Children admitted to the PICU with either a low predicted mortality risk (< 1%) or high predicted mortality risk (≥ 30%). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: In total, 419 patients were included (102 LN, 107 LS, 104 HN, and 106 HS). LN had more complex chronic conditions (93.1%) than LS (72.9%; p < 0.01), HN (49.0%; p < 0.001), and HS (48.1%; p < 0.001). The occurrence of adverse events in LN (76.5%) was higher than in LS (13.1%) and HN (47.1%) ( p < 0.001). The most frequent adverse events in LN were hospital-acquired infections and drug/fluid-related adverse events. LN suffered from more severe adverse events compared with LS and HS ( p < 0.001). In 30.4% of LN, an adverse event contributed to death. In 8.8%, this adverse event was considered preventable. CONCLUSIONS: Significant and preventable adverse events were found in low-risk PICU nonsurvivors. 76.5% of LN had one or more adverse events. In 30.4% of LN, an adverse event contributed to mortality.

A pilot randomised controlled trial assessing standard versus dermal patch-augmented rotator cuff repair found no adverse effects and suggest future trials need a minimum of 150 patients.

PURPOSE: The aims of this pilot randomised controlled trial (RCT) were to assess the safety and efficacy of a human dermal allograft patch and assess the feasibility of a future RCT comparing retear rate and functional outcome 12 months following standard and augmented double-row rotator cuff repair. METHODS:  A pilot RCT was conducted among patients undergoing arthroscopic repair of rotator cuff tear measuring between 1 and 5 cm. They were randomised to either augmented (double-row repair with human acellular dermal patch) or standard (double-row repair only). The primary outcome was rotator cuff retear determined on MRI scan at 12 months using the Sugaya's classification (grade 4 or 5). All adverse events were recorded. Functional assessment was performed at baseline and 3, 6, 9, and 12 months post-surgery using clinical outcome scores. Safety was assessed by complications and adverse effects, and feasibility by recruitment, follow-up rate and proof of concept statistical analyses of a future trial. RESULTS: Between 2017 and 2019, 63 patients were considered for inclusion. Twenty-three patients were excluded, leaving 40 patients (20 per group) in the final study population. The mean tear sizes were 3.0 cm in the augmented and 2.4 cm in the standard group. There was one adhesive capsulitis in the augmented group, with no other adverse events. Retear was observed in 4/18 (22%) of patients in the augmented and 5/18 (28%) in the standard group. In both groups, functional outcome improved significantly which was clinically meaningful for all scores, with no difference between groups. Retear rate increased with tear size. Future trials are feasible but need a minimum total sample size of 150 patients. CONCLUSION:  Clinically meaningful improved function without adverse effects was found with human acellular dermal patch-augmented cuff repairs. LEVEL OF EVIDENCE: Level II.

Bridging Theories for Ecosystem Stability Through Structural Sensitivity Analysis of Ecological Models in Equilibrium.

Ecologists are challenged by the need to bridge and synthesize different approaches and theories to obtain a coherent understanding of ecosystems in a changing world. Both food web theory and regime shift theory shine light on mechanisms that confer stability to ecosystems, but from different angles. Empirical food web models are developed to analyze how equilibria in real multi-trophic ecosystems are shaped by species interactions, and often include linear functional response terms for simple estimation of interaction strengths from observations. Models of regime shifts focus on qualitative changes of equilibrium points in a slowly changing environment, and typically include non-linear functional response terms. Currently, it is unclear how the stability of an empirical food web model, expressed as the rate of system recovery after a small perturbation, relates to the vulnerability of the ecosystem to collapse. Here, we conduct structural sensitivity analyses of classical consumer-resource models in equilibrium along an environmental gradient. Specifically, we change non-proportional interaction terms into proportional ones, while maintaining the equilibrium biomass densities and material flux rates, to analyze how alternative model formulations shape the stability properties of the equilibria. The results reveal no consistent relationship between the stability of the original models and the proportionalized versions, even though they describe the same biomass values and material flows. We use these findings to critically discuss whether stability analysis of observed equilibria by empirical food web models can provide insight into regime shift dynamics, and highlight the challenge of bridging alternative modelling approaches in ecology and beyond.

Activating Transcription Factor 6 Mediates Inflammatory Signals in Intestinal Epithelial Cells Upon Endoplasmic Reticulum Stress.

BACKGROUND & AIMS: Excess and unresolved endoplasmic reticulum (ER) stress in intestinal epithelial cells (IECs) promotes intestinal inflammation. Activating transcription factor 6 (ATF6) is one of the signaling mediators of ER stress. We studied the pathways that regulate ATF6 and its role for inflammation in IECs. METHODS: We performed an RNA interference screen, using 23,349 unique small interfering RNAs targeting 7783 genes and a luciferase reporter controlled by an ATF6-dependent ERSE (ER stress-response element) promoter, to identify proteins that activate or inhibit the ATF6 signaling pathway in HEK293 cells. To validate the screening results, intestinal epithelial cell lines (Caco-2 cells) were transfected with small interfering RNAs or with a plasmid overexpressing a constitutively active form of ATF6. Caco-2 cells with a CRISPR-mediated disruption of autophagy related 16 like 1 gene (ATG16L1) were used to study the effect of ATF6 on ER stress in autophagy-deficient cells. We also studied intestinal organoids derived from mice that overexpress constitutively active ATF6, from mice with deletion of the autophagy related 16 like 1 or X-Box binding protein 1 gene in IECs (Atg16l1ΔIEC or Xbp1ΔIEC, which both develop spontaneous ileitis), from patients with Crohn's disease (CD) and healthy individuals (controls). Cells and organoids were incubated with tunicamycin to induce ER stress and/or chemical inhibitors of newly identified activator proteins of ATF6 signaling, and analyzed by real-time polymerase chain reaction and immunoblots. Atg16l1ΔIEC and control (Atg16l1fl/fl) mice were given intraperitoneal injections of tunicamycin and were treated with chemical inhibitors of ATF6 activating proteins. RESULTS: We identified and validated 15 suppressors and 7 activators of the ATF6 signaling pathway; activators included the regulatory subunit of casein kinase 2 (CSNK2B) and acyl-CoA synthetase long chain family member 1 (ACSL1). Knockdown or chemical inhibition of CSNK2B and ACSL1 in Caco-2 cells reduced activity of the ATF6-dependent ERSE reporter gene, diminished transcription of the ATF6 target genes HSP90B1 and HSPA5 and reduced NF-κB reporter gene activation on tunicamycin stimulation. Atg16l1ΔIEC and or Xbp1ΔIEC organoids showed increased expression of ATF6 and its target genes. Inhibitors of ACSL1 or CSNK2B prevented activation of ATF6 and reduced CXCL1 and tumor necrosis factor (TNF) expression in these organoids on induction of ER stress with tunicamycin. Injection of mice with inhibitors of ACSL1 or CSNK2B significantly reduced tunicamycin-mediated intestinal inflammation and IEC death and expression of CXCL1 and TNF in Atg16l1ΔIEC mice. Purified ileal IECs from patients with CD had higher levels of ATF6, CSNK2B, and HSPA5 messenger RNAs than controls; early-passage organoids from patients with active CD show increased levels of activated ATF6 protein, incubation of these organoids with inhibitors of ACSL1 or CSNK2B reduced transcription of ATF6 target genes, including TNF. CONCLUSIONS: Ileal IECs from patients with CD have higher levels of activated ATF6, which is regulated by CSNK2B and HSPA5. ATF6 increases expression of TNF and other inflammatory cytokines in response to ER stress in these cells and in organoids from Atg16l1ΔIEC and Xbp1ΔIEC mice. Strategies to inhibit the ATF6 signaling pathway might be developed for treatment of inflammatory bowel diseases.

IL23R on myeloid cells is involved in murine pulmonary granuloma formation.

PURPOSE OF THE STUDY: The involvement of the IL-23/IL23R pathway is well known in the disease pathogenesis of sarcoidosis and other inflammatory diseases. To date, the pathogenic mechanism of IL-23 is most notably described on CD4+ Th17 lymphocytes. However, the function of the IL23R on myeloid cells in sarcoidosis is poorly understood. Thus, the aim of the study is to investigate the role of the IL23R on myeloid cell in pulmonary granuloma formation. Methods: We generated IL23RLysMCre mice lacking the IL23R gene in myeloid cells. The importance of IL23R in myeloid cells for the development of sarcoidosis was studied in a mouse model of inflammatory lung granuloma formation through embolization of PPD from Mycobacterium bovis-coated Sepharose beads into previously PPD-immunized mice. In addition the function of IL23R on myeloid cells was studied in LPS or IFNγ stimulated BMDMs and BMDCs. The mRNA and protein expression levels of relevant cytokines were analyzed by RT-PCR (TaqMan) and ELISA. The composition of immune cells in BALF was quantified by flow cytometry and alteration in granuloma sizes were observed by H&E stained lung sections. Results: Mycobacterium Ag-elicted pulmonary granulomas tend to be smaller in IL23RLysMCre mice and NF-κB dependent Th1 cytokines in the murine lungs are reduced compared to wildtype mice. In line, we observed that IL23R-deficient bone marrow-derived macrophages show a reduced production of Th1 cytokines after LPS stimulation. Conclusion: We here for the first time demonstrate a role for IL23R on myeloid cells in pulmonary inflammation and granuloma formation. Our findings provide essential insights in the pathogenesis of inflammatory lung diseases like sarcoidosis, which might be useful for the development of novel therapeutics targeting distinct immunological pathways like IL-23/IL23R.

Contralateral strength training attenuates muscle performance loss following anterior cruciate ligament (ACL) reconstruction: a randomised-controlled trial.

PURPOSE: To investigate the effects of cross-education (CE) exercise on strength and performance at 10 and 24 weeks post anterior cruciate ligament (ACL) surgery. METHODS: Design: randomised controlled trial. N = 44 ACL-reconstruction patients, randomly-allocated into: CE: strength training of the non-operative limb, or CON: sham exercise of upper limb stretching. Each patient underwent standardised ACL rehabilitation, plus 8 weeks of thrice weekly CE or CON, commencing at 2 weeks post surgery. The primary outcome was quadriceps peak force (QPF) of the ACL-reconstructed limb at 10 weeks post surgery. Secondary measures were hamstrings peak force (HPF), rate of force development (RFD) and International Knee Documentation Committee score (IKDC) at 10 and 24 weeks; QPF and hop for distance (HOP) at 24 weeks post surgery. RESULTS: CE significantly attenuated the decline in QPF of the ACL-reconstructed limb at 10 weeks compared to CON (16.6% decrease vs. 32.0%, respectively); that advantage was not retained at 24 weeks. A training effect was observed in the trained limb for HPF and QPF, which was retained at 24 weeks. No significant differences were observed for IKDC, HOP, RFD, or HPF of the reconstructed limb. Inter-limb symmetry (ILS) ranged from 0.78 to 0.89 and was not significantly different between groups. CONCLUSION: High-intensity CE strength training attenuated the post-operative decline in QPF and should be considered in early-phase ACL rehabilitation. ILS data showed good symmetry, but it masked significantly inferior performance between groups and should be used with caution. TRIAL REGISTRATION NUMBER: NCT02722876.

Does statin-treated hyperlipidemia affect rotator cuff healing or muscle fatty infiltration after rotator cuff repair?

BACKGROUND: Hyperlipidemia is linked to poor tendon-to-bone healing and progression of fatty infiltration after rotator cuff repair. Statins effectively treat hyperlipidemia, but it is unknown if they have any potential detrimental effects following rotator cuff repair. The aim of this study was to evaluate the effect of statins on rotator cuff healing and fatty infiltration following repair. METHODS: A total of 77 patients undergoing arthroscopic rotator cuff repair were recruited prospectively, 38 patients who were prescribed a statin for hyperlipidemia (statin group) and 39 patients who were not taking a statin (control group). Patients who did not have both preoperative and 1-year postoperative magnetic resonance imaging (MRI) scans were excluded from the study. Patient-reported outcome measures, namely the Western Ontario Rotator Cuff (WORC) index, Constant-Murley score, American Shoulder and Elbow Surgeons (ASES) score, and Disabilities of the Arm, Shoulder and Hand (DASH) score, were collected preoperatively and at 1 year. Fatty infiltration was assessed on MRI according to the Goutallier grade preoperatively and at 12 months; rotator cuff healing was assessed at 12 months according to the Sugaya classification. Following propensity score weighting to adjust for baseline imbalances, 12-month outcomes were compared between the 2 groups. RESULTS: At 12 months, all patient-reported outcome measures had improved significantly compared with baseline (WORC score, 85.9 vs. 32.5, P < .001; ASES score, 87.3 vs. 37.5, P < .001; Constant-Murley score, 77 vs. 31, P < .001; and DASH score, 13.6 vs. 61.4, P < .001). There was no significant difference in postoperative scores in the statin group vs. the control group (WORC score, 84.9 vs. 89.6, P = .94; ASES score, 87.5 vs. 86.6, P = .40; Constant-Murley score, 77 vs. 81, P = .90; and DASH score, 14.4 vs. 11.4, P = .14), and for 3 of these scores, the 95% confidence intervals excluded a clinically meaningful difference. Similarly, rotator cuff healing at 12 months and Goutallier fatty infiltration grades were comparable between the 2 groups. Retears were seen in 6 patients (15.8%) in the statin group and 8 (20.5%) in the control group. Progression of fatty infiltration was seen in 4 patients (10.5%) in the statin and 4 (10.3%) in the control group. Statin use did not demonstrate a significant association with either retear risk (P = .41) or progression of fatty atrophy (P = .69). CONCLUSION: Patient-reported outcomes, rotator cuff retear rate, and fatty infiltration on MRI at 12 months after rotator cuff repair in patients with hyperlipidemia treated with statins are similar to those in a control group.

Development of a total hip replacement phantom for the assessment of CT-image quality.

BACKGROUND: The quality of computed tomography (CT) imaging is important when used to judge the success of joint replacement surgery. Metal artefacts are a known source of error, typically compensated by noise reduction software. PURPOSE: To develop a transportable and stable system for the assessment of image quality of bone lesions around orthopedic implants. MATERIAL AND METHODS: The design and manufacture of a bone-implant-phantom is described, which is based on a calf acetabulum with surrounding pelvic bone structures. Bone lesions of several sizes were created in the acetabulum before implanting the cup of an uncemented hip prosthesis, which was fixed with a stainless-steel bone screw. Plastic strips were placed on a cobalt-chromium stemmed femoral component, simulating typical bone lesions around loosening or infected prostheses, before embedding the stem in material similar to bone and shaped like a femur. The head of the femoral component was then placed in the acetabular cup and CT scans were produced. RESULTS: It was possible to construct a durable CT hip phantom for quality assurance work. The usability of different materials and the choices made for the phantom are discussed. CONCLUSION: It is possible to construct a durable joint implant phantom for quality assurance and scanner hardware and software assessment with limited resources. The phantom was successfully used in the assessment of the hardware and software performance of different CT scanners.

Properties and Function of the Flexor Hallucis Capsularis Interphalangeus Tendon.

INTRODUCTION: The fibrocartilagenous plantar plates of the forefoot are biomechanically important, forming the primary distal attachment for the plantar aponeurosis. They are integral to the function of the windlass mechanism in supporting the arches of the foot in gait. Dissection of the cadaveric hallux revealed an organised sagittal thickening of the dorsal side of the flexor hallucis longus (FHL) sheath, which attached the interphalangeal plantar plate to the metatarsophalangeal (MTP) plantar plate. A description of a similar structure was made in 1984 when it was termed the flexor hallucis capsularis interphalangeus (FHCI) - however, it has not been researched since, and we aim to study it further and identify its characteristics. METHOD: Eight specimens were dissected from four cadavers. Two were stained and examined under magnification in both polarized and non polarized light. The remaining 6 were subjected to micrometer testing of their tensile properties. RESULTS: Both the histological features and mechanical properties were consistent with tendon; with cross sectional area, ultimate tensile strength and stiffness varying between specimens. CONCLUSIONS: Based on its location and properties, the FHCI tendon may be involved in limiting dorsiflexion of the first MTP joint and could have clinical relevance in pathological processes around both the first and second MTP joints. Clin. Anat., 33:689-695, 2020. © 2019 Wiley Periodicals, Inc.

Increasing the dose of oral vitamin K prophylaxis and its effect on bleeding risk.

Vitamin K prophylaxis in infancy aims to prevent life-threatening vitamin K deficiency bleeding (VKDB). The Dutch prophylactic oral daily regimen was increased sixfold from 25 to 150 µg because of a high failure rate. To evaluate the efficacy of this new regimen, incidences of intracranial VKDB under both regimens were compared using both general and targeted surveillance. Late VKDB in the general pediatric population was identified by the Netherlands Pediatric Surveillance Unit, between 1 October 2014 and 31 December 2016. Additionally, infants with intracranial vitamin K deficiency bleeding were identified using the Dutch Pediatric Intensive Care Evaluation registry. The incidence of intracranial VKDB as assessed by general and targeted surveillance decreased from 1.6 per 100,000 (95% CI, 0.4-5.1) to 1.3 per 100,000 (95% CI, 0.5-3.2) and from 3.1 per 100,000 live births (95% CI, 1.9-5.0) to 1.2 per 100,000 live births (95% CI, 0.6-2.3), respectively. Median time between consecutive cases in the latter increased from 24 to 154 days (p < 0.001).Conclusion: A sixfold increase in oral vitamin K prophylaxis was associated with a surprisingly modest reduction in the incidence of intracranial VKDB, indicating that factors other than the dose need addressing to improve efficacy. What is Known: • The efficacy of intramuscular vitamin K prophylaxis is threatened by an increasing number of parents opting out. • Oral prophylaxis represents an attractive and less invasive alternative but is inferior, especially in infants with malabsorption of vitamin K due to cholestasis. What is New: • Increasing the daily oral dose of vitamin K sixfold had a surprisingly modest effect on the incidence of late vitamin K deficiency bleeding. • This finding indicates that factors other than the dose must play an important role.

Hydrological regulation drives regime shifts: evidence from paleolimnology and ecosystem modeling of a large shallow Chinese lake.

Quantitative evidence of sudden shifts in ecological structure and function in large shallow lakes is rare, even though they provide essential benefits to society. Such 'regime shifts' can be driven by human activities which degrade ecological stability including water level control (WLC) and nutrient loading. Interactions between WLC and nutrient loading on the long-term dynamics of shallow lake ecosystems are, however, often overlooked and largely underestimated, which has hampered the effectiveness of lake management. Here, we focus on a large shallow lake (Lake Chaohu) located in one of the most densely populated areas in China, the lower Yangtze River floodplain, which has undergone both WLC and increasing nutrient loading over the last several decades. We applied a novel methodology that combines consistent evidence from both paleolimnological records and ecosystem modeling to overcome the hurdle of data insufficiency and to unravel the drivers and underlying mechanisms in ecosystem dynamics. We identified the occurrence of two regime shifts: one in 1963, characterized by the abrupt disappearance of submerged vegetation, and another around 1980, with strong algal blooms being observed thereafter. Using model scenarios, we further disentangled the roles of WLC and nutrient loading, showing that the 1963 shift was predominantly triggered by WLC, whereas the shift ca. 1980 was attributed to aggravated nutrient loading. Our analysis also shows interactions between these two stressors. Compared to the dynamics driven by nutrient loading alone, WLC reduced the critical P loading and resulted in earlier disappearance of submerged vegetation and emergence of algal blooms by approximately 26 and 10 years, respectively. Overall, our study reveals the significant role of hydrological regulation in driving shallow lake ecosystem dynamics, and it highlights the urgency of using multi-objective management criteria that includes ecological sustainability perspectives when implementing hydrological regulation for aquatic ecosystems around the globe.

Non-contraceptive oestrogen-containing preparations for controlling symptoms of premenstrual syndrome.

BACKGROUND: Premenstrual syndrome (PMS) is a psychological and somatic disorder of unknown aetiology, with symptoms typically including irritability, depression, mood swings, bloating, breast tenderness and sleep disturbances. About 3% to 10% of women who experience these symptoms may also meet criteria for premenstrual dysphoric disorder (PMDD). PMS symptoms recur during the luteal phase of the menstrual cycle and reduce by the end of menstruation. PMS results from ovulation and may be due to ovarian steroid interactions relating to neurotransmitter dysfunction. Premenstrual disorders have a devastating effect on women, their families and their work.Several treatment options have been suggested for PMS, including pharmacological and surgical interventions. The treatments thought to be most effective tend to fall into one of two categories: suppressing ovulation or correcting a speculated neuroendocrine anomaly.Transdermal oestradiol by patch, gel or implant effectively stops ovulation and the cyclical hormonal changes which produce the cyclical symptoms. These preparations are normally used for hormone therapy and contain lower doses of oestrogen than found in oral contraceptive pills. A shortened seven-day course of a progestogen is required each month for endometrial protection but can reproduce premenstrual syndrome-type symptoms in these women. OBJECTIVES: To determine the effectiveness and safety of non-contraceptive oestrogen-containing preparations in the management of PMS. SEARCH METHODS: On 14 March 2016, we searched the following databases: the Cochrane Gynaecology and Fertility Group (CGF) Specialised Register; Cochrane Central Register of Studies (CRSO); MEDLINE; Embase; PsycINFO; CINAHL; ClinicalTrials.gov; metaRegister of Controlled trials (mRCT); and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) Search Portal. In addition, we checked the reference lists of articles retrieved. SELECTION CRITERIA: We included published and unpublished randomized placebo or active controlled trials on the efficacy of the use of non-contraceptive oestrogen-containing preparations in the management of premenstrual syndrome in women of reproductive age with PMS diagnosed by at least two prospective cycles without current psychiatric disorder. DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies, assessed risk of bias, extracted data on premenstrual symptoms and adverse effects and entered data into Review Manager 5 software. Where possible, intention-to-treat or modified intention-to-treat analysis was used. Studies were pooled using a fixed-effect model, analysing cross-over trials as parallel trials. Standardised mean differences (SMDs) with 95% confidence intervals (CIs) were calculated for premenstrual symptom scores. Risk ratios (RRs) with 95% confidence intervals (CIs) were calculated for dichotomous outcomes. The overall quality of the evidence was assessed using the GRADE working group methods. MAIN RESULTS: The search resulted in 524 potentially relevant articles. Five eligible randomized controlled trials (RCTs) were identified (305 women). Trials using oral tablets, transdermal patches and implants were identified. No trial used gels.One small cross-over trial (11 women, effective sample size 22 women considering cross-over trials) compared oral luteal-phase oestrogen versus placebo. Data were very low quality and unsuitable for analysis, but study authors reported that the intervention was ineffective and might aggravate the symptoms of PMS. They also reported that there were no adverse events.Three studies compared continuous oestrogen with progestogen versus placebo (with or without progestogen). These trials were of reasonable quality, although with a high risk of attrition bias and an unclear risk of bias due to potential carry-over effects in two cross-over trials. Continuous oestrogen had a small to moderate positive effect on global symptom scores (SMD -0.34, 95% CI -0.59 to -0.10, P = 0.005, 3 RCTs, 158 women, effective sample size 267 women, I² = 63%, very low quality evidence). The evidence was too imprecise to determine if the groups differed in withdrawal rates due to adverse effects (RR 0.64, 95% CI 0.26 to 1.58, P = 0.33, 3 RCTs, 196 women, effective sample size 284 women, I² = 0%, very low quality evidence). Similarly, the evidence was very imprecise in measures of specific adverse events, with large uncertainties around the true value of the relative risk. None of the studies reported on long-term risks such as endometrial cancer or breast cancer.One study compared patch dosage (100 vs 200 µg oestrogen, with progestogen in both arms) and had a high risk of performance bias, detection bias and attrition bias. The study did not find evidence that dosage affects global symptoms but there was much uncertainty around the effect estimate (SMD -1.55, 95% CI -8.88 to 5.78, P = 0.68, 1 RCT, 98 women, very low quality evidence). The evidence on rates of withdrawal for adverse events was too imprecise to draw any conclusions (RR 0.70, 95% CI 0.34 to 1.46, P = 0.34, 1 RCT, 107 women, low-quality evidence). However, it appeared that the 100 µg dose might be associated with a lower overall risk of adverse events attributed to oestrogen (RR 0.51, 95% Cl 0.26 to 0.99, P = 0.05, 1 RCT, 107 women, very low quality evidence) with a large uncertainty around the effect estimate.The overall quality of the evidence for all comparisons was very low, mainly due to risk of bias (specifically attrition), imprecision, and statistical and clinical heterogeneity. AUTHORS' CONCLUSIONS: We found very low quality evidence to support the effectiveness of continuous oestrogen (transdermal patches or subcutaneous implants) plus progestogen, with a small to moderate effect size. We found very low quality evidence from a study based on 11 women to suggest that luteal-phase oral unopposed oestrogen is probably ineffective and possibly detrimental for controlling the symptoms of PMS. A comparison between 200 µg and 100 µg doses of continuous oestrogen was inconclusive with regard to effectiveness, but suggested that the lower dose was less likely to cause side effects. Uncertainty remains regarding safety, as the identified studies were too small to provide definite answers. Moreover, no included trial addressed adverse effects that might occur beyond the typical trial duration of 2-8 months. This suggests the choice of oestrogen dose and mode of administration could be based on an individual woman's preference and modified according to the effectiveness and tolerability of the chosen regimen.

Mowing Submerged Macrophytes in Shallow Lakes with Alternative Stable States: Battling the Good Guys?

Submerged macrophytes play an important role in maintaining good water quality in shallow lakes. Yet extensive stands easily interfere with various services provided by these lakes, and harvesting is increasingly applied as a management measure. Because shallow lakes may possess alternative stable states over a wide range of environmental conditions, designing a successful mowing strategy is challenging, given the important role of macrophytes in stabilizing the clear water state. In this study, the integrated ecosystem model PCLake is used to explore the consequences of mowing, in terms of reducing nuisance and ecosystem stability, for a wide range of external nutrient loadings, mowing intensities and timings. Elodea is used as a model species. Additionally, we use PCLake to estimate how much phosphorus is removed with the harvested biomass, and evaluate the long-term effect of harvesting. Our model indicates that mowing can temporarily reduce nuisance caused by submerged plants in the first weeks after cutting, particularly when external nutrient loading is fairly low. The risk of instigating a regime shift can be tempered by mowing halfway the growing season when the resilience of the system is highest, as our model showed. Up to half of the phosphorus entering the system can potentially be removed along with the harvested biomass. As a result, prolonged mowing can prevent an oligo-to mesotrophic lake from becoming eutrophic to a certain extent, as our model shows that the critical nutrient loading, where the lake shifts to the turbid phytoplankton-dominated state, can be slightly increased.

Safety of the Manchester Triage System to Detect Critically Ill Children at the Emergency Department.

OBJECTIVE: To assess the safety of the Manchester Triage System in pediatric emergency care for children who require admission to the intensive care unit (ICU). STUDY DESIGN: Between 2006 and 2013, 50 062 consecutive emergency department visits of children younger than the age of 16 years were included. We determined the percentage of undertriage, defined as the proportion of children admitted to ICU triaged as low urgent according to the Manchester Triage System, and diagnostic performance measures, including sensitivity, specificity, and diagnostic OR. Characteristics of undertriaged patients were compared with correctly triaged patients. In a logistic regression model, risk factors for undertriage were determined. RESULTS: In total, 238 (28.7%) of the 830 children admitted to ICU during the study period were undertriaged. Sensitivity of high Manchester Triage System urgency levels to detect ICU admission was 71% (95% CI 68%-74%) and specificity 85% (95% CI 85%-85%). Severity of illness was lower in undertriaged children than correctly triaged children admitted to ICU. Risk factors for undertriage were age <3 months, medical presenting problem, comorbidity, referral by a medical specialist or emergency medical services, and presentation during the evening or night shift. CONCLUSION: The Manchester Triage System misclassifies a substantial number of children who require ICU admission. Modifications targeted at young children and children with a comorbid condition could possibly improve safety of the Manchester Triage System in pediatric emergency care.

Biomechanical analysis of tension band wiring (TBW) of transverse fractures of patella.

PURPOSE: Tension band wiring is commonly used for fixation of simple transverse fractures. The popular configuration is parallel Kirschner wires (K-wires) and a stainless steel wire loop placed in a vertically oriented figure-of-8. METHODS: We used a wooden model of a patella with a midway transverse fracture and compared four different types of fixation. The first construct had a vertical figure-of-8 with one twist of wire. The second contained a vertical figure-of-8 with two twists of wire. The third was a vertical figure-of-8 with two twists of wire placed at adjacent corners while the last one had a horizontal figure-of-8 with two twists of wire placed at adjacent corners. Interfragmentary compression at the point of wire breakage was measured for each construct as well as permanent displacement on cyclic loading. RESULTS: Placement of the figure-of-eight in a horizontal orientation with two wire twists at the corner improved interfragmentary compression by 63% (p < 0.05, Tukey post hoc test). On cyclic loading, all the constructs with vertical figure-of-eight but none with a horizontal construct failed (p=0.01; Fisher's exact test). Permanent fracture displacement after cyclic loading was 67% lower with horizontal figure- of-eight constructs (p < 0.05; t test). CONCLUSION: Placing wire twists at the corner and a horizontal placement of figure-of-8 improves stability of the construct.

Competition for light and nutrients in layered communities of aquatic plants.

Dominance of free-floating plants poses a threat to biodiversity in many freshwater ecosystems. Here we propose a theoretical framework to understand this dominance, by modeling the competition for light and nutrients in a layered community of floating and submerged plants. The model shows that at high supply of light and nutrients, floating plants always dominate due to their primacy for light, even when submerged plants have lower minimal resource requirements. The model also shows that floating-plant dominance cannot be an alternative stable state in light-limited environments but only in nutrient-limited environments, depending on the plants' resource consumption traits. Compared to unlayered communities, the asymmetry in competition for light-coincident with symmetry in competition for nutrients-leads to fundamentally different results: competition outcomes can no longer be predicted from species traits such as minimal resource requirements ([Formula: see text] rule) and resource consumption. Also, the same two species can, depending on the environment, coexist or be alternative stable states. When applied to two common plant species in temperate regions, both the model and field data suggest that floating-plant dominance is unlikely to be an alternative stable state.

Efficacy of hip resurfacing arthroplasty: 6 year results from an international multisurgeon prospective cohort study.

Metal-on-metal hip resurfacing is undertaken worldwide. This procedure helps preserve femoral bone stock and allows patients to return to high activity sports. Most outcome studies are individual surgeon case series from single centers where the results and outcomes are evaluated by the same surgeon. One method of increasing the external validity of a follow-up study is to have a multi-centre study design with independent assessment of the outcomes. We present an independent assessment of eleven year follow-up of hip resurfacing outcomes from an international hip resurfacing register. The purpose of this study was to assess: Implant survival at maximum follow-up for revision due to any reason, implant survival at maximum follow-up for revision due to major causes of failure, hip function following hip resurfacing and factors affecting hip function, effect of gender and age on hip function and implant survival, effect of femoral component size on hip function and implant survival. 4535 patients (5000 hips) entered into the registry during 1997-2002 were studied. In summary, at a maximum follow-up of 11 years hip resurfacing has a good implant survival of 96.2% and excellent post-operative function. This is excellent given the international and multisurgeon nature of this cohort where majority of the surgeons were in their learning curve.