Most organisms show substantial changes in size or morphology after they become independent of their parents and have to find their own food. Furthermore, the rate at which these changes occur ...generally depends on the amount of food they ingest. In this book, André de Roos and Lennart Persson advance a synthetic and individual-based theory of the effects of this plastic ontogenetic development on the dynamics of populations and communities.
De Roos and Persson show how the effects of ontogenetic development on ecological dynamics critically depend on the efficiency with which differently sized individuals convert food into new biomass. Differences in this efficiency--or ontogenetic asymmetry--lead to bottlenecks in and thus population regulation by either maturation or reproduction. De Roos and Persson investigate the community consequences of these bottlenecks for trophic configurations that vary in the number and type of interacting species and in the degree of ontogenetic niche shifts exhibited by their individuals. They also demonstrate how insights into the effects of maturation and reproduction limitation on community equilibrium carry over to the dynamics of size-structured populations and give rise to different types of cohort-driven cycles.
Featuring numerous examples and tests of modeling predictions, this book provides a pioneering and extensive theoretical and empirical treatment of the ecology of ontogenetic growth and development in organisms, emphasizing the importance of an individual-based perspective for understanding population and community dynamics.
Osteoarthritis (OA) has been thought of as a disease of cartilage that can be effectively treated surgically at severe stages with joint arthroplasty. Today, OA is considered a whole-organ disease ...that is amenable to prevention and treatment at early stages. OA develops slowly over 10-15 years, interfering with activities of daily living and the ability to work. Many patients tolerate pain, and many health-care providers accept pain and disability as inevitable corollaries of OA and ageing. Too often, health-care providers passively await final 'joint death', necessitating knee and hip replacements. Instead, OA should be viewed as a chronic condition, where prevention and early comprehensive-care models are the accepted norm, as is the case with other chronic diseases. Joint injury, obesity and impaired muscle function are modifiable risk factors amenable to primary and secondary prevention strategies. The strategies that are most appropriate for each patient should be identified, by selecting interventions to correct--or at least attenuate--OA risk factors. We must also choose the interventions that are most likely to be acceptable to patients, to maximize adherence to--and persistence with--the regimes. Now is the time to begin the era of personalized prevention for knee OA.
In this randomized, controlled trial of young, active adults with an acute anterior cruciate ligament (ACL) injury, rehabilitation plus early ACL reconstruction was not superior to rehabilitation ...plus optional delayed ACL reconstruction with respect to pain, symptoms, knee function, and knee-related quality of life, and it resulted in significantly more knee reconstructions.
Rupture of the anterior cruciate ligament (ACL) is a serious knee injury that affects mainly physically active young people. The injury is characterized by joint instability that leads to decreased activity, unsatisfactory knee function, and poor knee-related quality of life in the short term,
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and it is associated with an increased risk of osteoarthritis of the knee.
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Surgical reconstruction of the torn ligament has been regarded as critical for a good outcome and is commonly performed, particularly in those wishing to resume sports activities.
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Despite a lack of evidence from high-quality randomized, controlled trials comparing ACL reconstruction . . .
Summary
The efficient spread of malaria from infected humans to mosquitoes is a major challenge for malaria elimination initiatives. Gametocytes are the only Plasmodium life stage infectious to ...mosquitoes. Here, we summarize evidence for naturally acquired anti‐gametocyte immunity and the current state of transmission blocking vaccines (TBV). Although gametocytes are intra‐erythrocytic when present in infected humans, developing Plasmodium falciparum gametocytes may express proteins on the surface of red blood cells that elicit immune responses in naturally exposed individuals. This immune response may reduce the burden of circulating gametocytes. For both P. falciparum and Plasmodium vivax, there is a solid evidence that antibodies against antigens present on the gametocyte surface, when co‐ingested with gametocytes, can influence transmission to mosquitoes. Transmission reducing immunity, reducing the burden of infection in mosquitoes, is a well‐acknowledged but poorly quantified phenomenon that forms the basis for the development of TBV. Transmission enhancing immunity, increasing the likelihood or intensity of transmission to mosquitoes, is more speculative in nature but is convincingly demonstrated for P. vivax. With the increased interest in malaria elimination, TBV and monoclonal antibodies have moved to the center stage of malaria vaccine development. Methodologies to prioritize and evaluate products are urgently needed.
Summary Objective To conduct a systematic review and meta-analysis to synthesise evidence regarding measurement properties of the Knee injury and Osteoarthritis Outcome Score (KOOS). Design A ...comprehensive literature search identified 37 eligible papers evaluating KOOS measurement properties in participants with knee injuries and/or osteoarthritis. Methodological quality was evaluated using the COSMIN checklist. Where possible, meta-analysis of extracted data was conducted for all studies and stratified by age and knee condition; otherwise narrative synthesis was performed. Results KOOS has adequate internal consistency, test-retest reliability and construct validity in young and old adults with knee injuries and/or osteoarthritis. The ADL subscale has better content validity for older patients and Sport/Rec for younger patients with knee injuries, while the Pain subscale is more relevant for painful knee conditions. The five-factor structure of the original KOOS is unclear. There is some evidence that the KOOS subscales demonstrate sufficient unidimensionality, but this requires confirmation. Although measurement error requires further evaluation, the minimal detectable change for KOOS subscales ranges from 14.3 to 19.6 for younger individuals, and ≥20 for older individuals. Evidence of responsiveness comes from larger effect sizes following surgical (especially total knee replacement) than non-surgical interventions. Conclusions KOOS demonstrates adequate content validity, internal consistency, test-retest reliability, construct validity and responsiveness for age- and condition-relevant subscales. Structural validity, cross-cultural validity and measurement error require further evaluation, as well as construct validity of KOOS-PS. Suggested order of subscales for different knee conditions can be applied in hierarchical testing of endpoints in clinical trials.
Understanding the full scope of human impact on wildlife populations requires a framework to assess the population-level repercussions of nonlethal disturbance. The Population Consequences of ...Disturbance (PCoD) framework provides such an approach, by linking the effects of disturbance on the behavior and physiology of individuals to their populationlevel consequences. Bio-energetic models have been used as implementations of PCoD, as these integrate the behavioral and physiological state of an individual with the state of the environment, to mediate between disturbance and biological significant changes in vital rates (survival, growth, and reproduction). To assess which levels of disturbance lead to adverse effects on population growth rate requires a bio-energetic model that covers the complete life cycle of the organism under study. In a density-independent setting, the expected lifetime reproductive output of a single female can then be used to predict the level of disturbance that leads to population decline. Here, we present such a model for a medium-sized cetacean, the long-finned pilot whale (Globicephala melas). Disturbance is modeled as a yearly recurrent period of no resource feeding for the pilot whale female and her calf. Short periods of disturbance lead to the pre-weaned death of the first one or more calves of the young female. Higher disturbance levels also affect survival of calves produced later in the life of the female, in addition to degrading female survival. The level of disturbance that leads to a negative population growth rate strongly depends on the available resources in the environment. This has important repercussion for the timing of disturbance if resource availability fluctuates seasonally. The model predicts that pilot whales can tolerate on average three times longer periods of disturbance in seasons of high resource availability, compared to disturbance happening when resources are low. Although our model is specifically parameterized for pilot whales, it provides useful insights into the general consequences of nonlethal disturbance. If appropriate data on life history and energetics are available, it can be used to provide management advice for specific species or populations.
Catastrophic and sudden collapses of ecosystems are sometimes preceded by early warning signals that potentially could be used to predict and prevent a forthcoming catastrophe. Universality of these ...early warning signals has been proposed, but no formal proof has been provided. Here, we show that in relatively simple ecological models the most commonly used early warning signals for a catastrophic collapse can be silent. We underpin the mathematical reason for this phenomenon, which involves the direction of the eigenvectors of the system. Our results demonstrate that claims on the universality of early warning signals are not correct, and that catastrophic collapses can occur without prior warning. In order to correctly predict a collapse and determine whether early warning signals precede the collapse, detailed knowledge of the mathematical structure of the approaching bifurcation is necessary. Unfortunately, such knowledge is often only obtained after the collapse has already occurred.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Antioxidants for male subfertility Smits, Roos M; Mackenzie‐Proctor, Rebecca; Yazdani, Anusch ...
Cochrane database of systematic reviews,
03/2019, Letnik:
2019, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Background
The inability to have children affects 10% to 15% of couples worldwide. A male factor is estimated to account for up to half of the infertility cases with between 25% to 87% of male ...subfertility considered to be due to the effect of oxidative stress. Oral supplementation with antioxidants is thought to improve sperm quality by reducing oxidative damage. Antioxidants are widely available and inexpensive when compared to other fertility treatments, however most antioxidants are uncontrolled by regulation and the evidence for their effectiveness is uncertain. We compared the benefits and risks of different antioxidants used for male subfertility. This review did not examine the use of antioxidants in normospermic men.
Objectives
To evaluate the effectiveness and safety of supplementary oral antioxidants in subfertile men.
Search methods
The Cochrane Gynaecology and Fertility (CGF) Group trials register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, and two trials registers were searched on 1 February 2018, together with reference checking and contact with study authors and experts in the field to identify additional trials.
Selection criteria
We included randomised controlled trials (RCTs) that compared any type, dose or combination of oral antioxidant supplement with placebo, no treatment or treatment with another antioxidant, among subfertile men of a couple attending a reproductive clinic. We excluded studies comparing antioxidants with fertility drugs alone and studies that included fertile men attending a fertility clinic because of female partner infertility.
Data collection and analysis
We used standard methodological procedures recommended by Cochrane. The primary review outcome was live birth. Clinical pregnancy, adverse events and sperm parameters were secondary outcomes.
Main results
We included 61 studies with a total population of 6264 subfertile men, aged between 18 and 65 years, part of a couple who had been referred to a fertility clinic and some of whom were undergoing assisted reproductive techniques (ART). Investigators compared and combined 18 different oral antioxidants. The evidence was of 'low' to 'very low' quality: the main limitation was that out of the 44 included studies in the meta‐analysis only 12 studies reported on live birth or clinical pregnancy. The evidence is current up to February 2018.
Live birth: antioxidants may lead to increased live birth rates (OR 1.79, 95% CI 1.20 to 2.67, P = 0.005, 7 RCTs, 750 men, I2 = 40%, low‐quality evidence). Results suggest that if in the studies contributing to the analysis of live birth rate, the baseline chance of live birth following placebo or no treatment is assumed to be 12%, the chance following the use of antioxidants is estimated to be between 14% and 26%. However, this result was based on only 124 live births from 750 couples in seven relatively small studies. When studies at high risk of bias were removed from the analysis, there was no evidence of increased live birth (Peto OR 1.38, 95% CI 0.89 to 2.16; participants = 540 men, 5 RCTs, P = 0.15, I2 = 0%).
Clinical pregnancy rate: antioxidants may lead to increased clinical pregnancy rates (OR 2.97, 95% CI 1.91 to 4.63, P < 0.0001, 11 RCTs, 786 men, I2 = 0%, low‐quality evidence) compared to placebo or no treatment. This suggests that if in the studies contributing to the analysis of clinical pregnancy, the baseline chance of clinical pregnancy following placebo or no treatment is assumed to be 7%, the chance following the use of antioxidants is estimated to be between 12% and 26%. This result was based on 105 clinical pregnancies from 786 couples in 11 small studies.
Adverse events
Miscarriage: only three studies reported on this outcome and the event rate was very low. There was no difference in miscarriage rate between the antioxidant and placebo or no treatment group (OR 1.74, 95% CI 0.40 to 7.60, P = 0.46, 3 RCTs, 247 men, I2 = 0%, very low‐quality evidence). The findings suggest that in a population of subfertile men with an expected miscarriage rate of 2%, the chance following the use of an antioxidant would result in the risk of a miscarriage between 1% and 13%.
Gastrointestinal: antioxidants may lead to an increase in mild gastrointestinal upsets when compared to placebo or no treatment (OR 2.51, 95% CI 1.25 to 5.03, P = 0.010, 11 RCTs, 948 men, I2 = 50%, very low‐quality evidence). This suggests that if the chance of gastrointestinal upsets following placebo or no treatment is assumed to be 2%, the chance following the use of antioxidants is estimated to be between 2% and 9%. However, this result was based on a low event rate of 35 out of 948 men in 10 small or medium‐sized studies, and the quality of the evidence was rated very low and was high in heterogeneity.
We were unable to draw any conclusions from the antioxidant versus antioxidant comparison as insufficient studies compared the same interventions.
Authors' conclusions
In this review, there is low‐quality evidence from seven small randomised controlled trials suggesting that antioxidant supplementation in subfertile males may improve live birth rates for couples attending fertility clinics. Low‐quality evidence suggests that clinical pregnancy rates may also increase. Overall, there is no evidence of increased risk of miscarriage, however antioxidants may give more mild gastrointestinal upsets but the evidence is of very low quality. Subfertilte couples should be advised that overall, the current evidence is inconclusive based on serious risk of bias due to poor reporting of methods of randomisation, failure to report on the clinical outcomes live birth rate and clinical pregnancy, often unclear or even high attrition, and also imprecision due to often low event rates and small overall sample sizes. Further large well‐designed randomised placebo‐controlled trials reporting on pregnancy and live births are still required to clarify the exact role of antioxidants.
Objective
To identify the optimal exercise program, characterized by type and intensity of exercise, length of program, duration of individual supervised sessions, and number of sessions per week, ...for reducing pain and patient‐reported disability in knee osteoarthritis (OA).
Methods
A systematic review and meta‐analysis of randomized controlled trials were performed. Standardized mean differences (SMDs) were combined using a random‐effects model. Study‐level covariates were applied in meta‐regression analyses in order to reduce between‐study heterogeneity.
Results
Forty‐eight trials were included. Similar effects in reducing pain were found for aerobic, resistance, and performance exercise (SMD 0.67, 0.62, and 0.48, respectively; P = 0.733). These single‐type exercise programs were more efficacious than programs that included different exercise types (SMD 0.61 versus 0.16; P < 0.001). The effect of aerobic exercise on pain relief increased with an increased number of supervised sessions (slope 0.022 95% confidence interval 0.002, 0.043). More pain reduction occurred with quadriceps‐specific exercise than with lower limb exercise (SMD 0.85 versus 0.39; P = 0.005) and when supervised exercise was performed at least 3 times a week (SMD 0.68 versus 0.41; P = 0.017). No impact of intensity, duration of individual sessions, or patient characteristics was found. Similar results were found for the effect on patient‐reported disability.
Conclusion
Optimal exercise programs for knee OA should have one aim and focus on improving aerobic capacity, quadriceps muscle strength, or lower extremity performance. For best results, the program should be supervised and carried out 3 times a week. Such programs have a similar effect regardless of patient characteristics, including radiographic severity and baseline pain.
Manganese is an attractive element for sustainable solutions. It is largely available in the earth's crust, making it ideal for cost‐effective and large‐scale applications. Especially MnO ...nanoparticles have recently received attention for applications in battery technology. However, manganese has many oxidation states that are energetically very similar, indicating that they may easily transform from one to the other. Herein, the reversible oxidation of MnO nanoparticles to Mn3O4 studied with in situ transmission electron microscopy is shown. The oxygen sublattices of MnO and Mn3O4 are found to be perfectly aligned, and an atomic mechanism where the transformation is facilitated by the migration of Mn cations on the shared O sublattice is proposed. Even when protected with an amorphous carbon layer, MnO particles are highly unstable and oxidize to Mn3O4 in ethanol. The poor stability of MnO lacks discussion in many battery‐related works, and strategies aimed at avoiding this should be developed.
MnO nanoparticles embedded in a carbon layer are synthesized and found to spontaneously transform to Mn3O4 under ambient conditions, which can be reversed by heating in vacuum. The transformation is investigated in detail with in situ transmission electron microscopy, giving important insights into the stability of MnO nanoparticles used in, for example, battery technology.
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