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BACKGROUND: The prevalence of metabolic syndrome (MetS) in American adults increased from 37.6% in the 2011-12 period to 41.8% in 2017-2018. Environmental exposure, particularly to common compounds such as glyphosate, has drawn increasing attention as a potential risk factor. METHODS: We employed three cycles of data (2013-2018) from the National Health and Nutrition Examination Survey (NHANES) in a cross-sectional study to examine potential associations between urine glyphosate measurements and MetS incidence. We first created a MetS score using exploratory factor analysis (EFA) of the International Diabetes Federation (IDF) criteria for MetS, with data drawn from the 2013-2018 NHANES cycles, and validated this score independently on an additional associated metric, the albumin-to-creatinine (ACR) ratio. The score was validated via a machine learning approach in predicting the ACR score via binary classification and then used in multivariable regression to test the association between quartile-categorized glyphosate exposure and the MetS score. RESULTS: In adjusted multivariable regressions, regressions between quartile-categorized glyphosate exposure and MetS score showed a significant inverted U-shaped or saturating doseâresponse profile, often with the largest effect for exposures in quartile 3. Exploration of potential effect modification by sex, race, and age category revealed significant differences by race and age, with older people (aged > 65 years) and non-Hispanic African American participants showing larger effect sizes for all exposure quartiles. CONCLUSIONS: We found that urinary glyphosate concentration is significantly associated with a statistical score designed to predict MetS status and that dose-response coefficient is nonlinear, with advanced age and non-Hispanic African American, Mexican American and other Hispanic participants exhibiting greater effect sizes.
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Glicina , Glifosato , Herbicidas , Inquéritos Nutricionais , Humanos , Glicina/análogos & derivados , Glicina/urina , Estudos Transversais , Masculino , Feminino , Pessoa de Meia-Idade , Adulto , Herbicidas/urina , Idoso , Síndrome Metabólica/urina , Síndrome Metabólica/epidemiologia , Síndrome Metabólica/induzido quimicamente , Estados Unidos/epidemiologia , Exposição Ambiental/análise , Adulto Jovem , Fatores de Risco , Poluentes Ambientais/urinaRESUMO
BACKGROUND: Long-chain omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are reported to be beneficial for cognition, but limited consumption of some fish is recommended due to high concentrations of heavy metals and persistent organics. OBJECTIVE: We aimed to determine whether dietary ω-3 PUFAs from fish consumption are associated with higher cognitive scores in older adults and explored the associations of mixtures of ω-3 PUFAs and blood concentrations of lead, cadmium, selenium, and methylmercury on cognitive performance. METHODS: We conducted a cross-sectional study with data from the NHANES 2011-2014, assessing cognitive scores of immediate recall, delayed recall, and executive function in adults ≥60 y (n = 3123). We performed multivariate linear regressions and mixture models utilizing the quantile-based g-computation method to identify associations between monthly fish consumption or dietary ω-3 PUFAs with blood concentrations of lead, cadmium, methyl mercury, and selenium on cognitive scores. RESULTS: Fish consumption had significant positive associations with all 3 cognitive scores, whereas dietary ω-3 PUFAs were only significantly associated with the Digit Symbol Substitution Test (DSST) scores. Mixture analysis showed significant positive associations with DSST scores for fish consumption (ß: 0.88; 95% CI: 0.48, 1.29) and dietary ω-3 PUFAs (ß: 0.41; 95% CI: 0.03, 0.78) with positive component weights for fish consumption, dietary ω-3 PUFAs, and blood selenium and negative component weight for blood cadmium concentrations. CONCLUSIONS: Our findings support dietary recommendations for older adults to consume fish to maintain cognitive function, likely due to biomolecular actions of ω-3 PUFAs that increase neuronal membrane fluidity, have antioxidation activity, and restore cell damage. The combination of selenium and fish consumption or ω-3 PUFAs was associated with reduced decline in cognitive scores and less negative associations from exposures to lead, cadmium, and mercury compounds.
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Ácidos Graxos Ômega-3 , Compostos de Metilmercúrio , Selênio , Animais , Humanos , Cádmio , Estudos Transversais , Chumbo , Inquéritos Nutricionais , Dieta , CogniçãoRESUMO
Late diagnosis of human immunodeficiency virus (HIV) is associated with early progression to acquired immunodeficiency syndrome (AIDS). We examined racial/ethnic differences in presentation with advanced HIV/AIDS at a community health center in New Jersey. Records of patients diagnosed with HIV between 1990 and 2018 were reviewed. Odds ratios (OR) of presenting with AIDS at HIV diagnosis were computed in unadjusted and adjusted models. There were 182 (48.3%) Latino, 48 (12.7%) non-Latino White (NLW), 130 (34.5%) non-Latino Black, and 17 (4.5%) non-Latino of other race/ethnicity included in the analysis. Over 75% of the Latinos were foreign-born. Latino patients had higher odds of presentation with AIDS at time of HIV diagnosis than NLW in unadjusted (OR = 4.85, 95% confidence interval (95% CI): 2.28-10.31) and adjusted models (OR = 3.71, 95%CI: 1.60-8.59). Latino patients, particularly foreign-born and bisexual, had higher odds of being diagnosed with AIDS at presentation with HIV in this cohort.
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Síndrome da Imunodeficiência Adquirida , Infecções por HIV , Humanos , Negro ou Afro-Americano , Diagnóstico Tardio , Hispânico ou Latino , HIV , New Jersey , Fatores de Risco , BrancosRESUMO
Air pollution increases risk of respiratory disease but prior research has focused on particulate matter and criteria air pollutants, and there are few studies on respiratory effects of volatile organic compounds (VOC). We examined zip code level relationships between emergency room (ER) visits for respiratory illness and VOC pollution in New York State from 2010 to 2018. Detailed information on VOC pollution was derived from the National Emissions Inventory, which provides point source information on VOC emissions at the zip code level. We considered four respiratory diseases: asthma, acute upper respiratory infections, chronic obstructive pulmonary disease (COPD), and lower respiratory disease, using mixed effects regression with a random intercept to account for county level variability in single pollutant models, and Random Forest Regression (RFR) to assess relative importance of VOC exposures when considered together in multipollutant models. Single pollutant models show associations between respiratory-related ER visits with all pollutants of interest across all study years, even after adjusting for poverty and smoking by zip code. The largest relative single pollutant effect sizes considered included benzene, ethylbenzene, and total (summed) VOCs. Results from RFR including all VOC exposures indicate that ethylbenzene has the greatest variable importance for asthma, acute upper respiratory infections, and COPD, with toluene and benzene most important for lower respiratory ailments. RFR results also demonstrate presence of pairwise interactive effects between VOC pollutants. Our findings show that local VOC pollution may offer a significant contribution to the risk of respiratory disease-related ER visits, and that effects vary by illness and by VOC compound. ER visit rates for respiratory illness were elevated in high poverty zip codes, although this may be attributable to the fact that the poor lack basic access to health care and use ERs more frequently for routine care.
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Poluentes Atmosféricos , Poluição do Ar , Asma , Doença Pulmonar Obstrutiva Crônica , Transtornos Respiratórios , Infecções Respiratórias , Compostos Orgânicos Voláteis , Humanos , Compostos Orgânicos Voláteis/análise , Exposição Ambiental/análise , Benzeno , Poluição do Ar/análise , Poluentes Atmosféricos/análise , Material Particulado/análiseRESUMO
PROBLEM: Previous studies document an association between mode of delivery (MOD) and allergic conditions in children. Immunoglobulin (Ig) concentrations at birth may play a role. The goal of this study is to assess the impact of MOD on Ig concentrations at delivery from newborn dried blood spots (DBS). METHOD OF STUDY: The Upstate KIDS Study (2008-2010) is a prospective cohort of mother-child pairs recruited from New York State, excluding New York City. Ig subtypes IgA, IgE, IgG1 , IgG2 , IgG3 , IgG4 , and IgM were measured in residual NDBS from the Newborn Screening Program (N = 3274 infants). MOD was categorized as vaginal delivery (VD), emergency cesarean delivery (ECD) or planned cesarean delivery (PCD). Associations between MOD and Ig levels were assessed using ANOVA and multiple regression, with models adjusted for gestational age, birth weight, maternal race, plurality, and smoking status. RESULTS: IgA, and the IgG subtypes IgG3 and IgG4 were found to be significantly lower in PCD neonates relative to VD neonates in adjusted regression models: 3.57 mg/ml, (95% CI: 3.51, 3.63) compared to 3.64 mg/ml (95% CI: 3.59, 3.69); 8.95 ng/ml (95% CI: 8.88,9.03) compared to 9.03 ng/ml (95% CI: 8.98, 9.08) and 8.05 ng/ml (95% CI: 7.91, 8.20) compared to 8.22 ng/ml (95% CI: 7.91,8.20), respectively. CONCLUSIONS: MOD may thus be related to neonatal immune profile. Results were found to be robust to sensitivity testing based on maternal complications and indication for CD. Clinical implications are unclear given the small levels of association found in newborns, but the result suggests greater susceptibility to infection, and further study is warranted.
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Cesárea , Parto , Gravidez , Feminino , Recém-Nascido , Lactente , Humanos , Estudos Prospectivos , Imunoglobulina A , Imunoglobulina GRESUMO
The Mohawks at Akwesasne have been highly exposed to polychlorinated biphenyls (PCBs), via releases from three aluminum foundries located near the reserve. They are also exposed to organochlorine pesticides, namely hexachlorobenzene (HCB), dichlorodiphenyldichloroethylene (DDE), and mirex. Previous studies have demonstrated reduced cognition in relation to total PCBs, but the effects of the mixtures of different PCB congener groups, HCB, DDE, and mirex on cognitive function have not been studied. Therefore, cognitive performance for executive function, scored via the digit symbol substitution test (DSST), in Mohawk adults aged 17-79 years (n = 301), was assessed in relation to serum concentrations of low-chlorinated PCBs, high-chlorinated PCBs, total PCBs, HCB, DDE, and mirex. We used mixture models employing the quantile-based g-computation method. The mixture effects of low-chlorinated PCBs, high-chlorinated PCBs, HCB, DDE, and mirex were significantly associated with 4.01 DSST scores decrements in the oldest age group, 47-79 years old. There were important contributions to mixture effects from low-chlorinated PCBs, high-chlorinated PCBs, and total PCBs, with smaller contributions of HCB and DDE. Our findings indicate that exposures to both low- and high-chlorinated PCBs increase the risk of cognitive decline in older adults, while DDE and HCB have less effect.
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Poluentes Ambientais , Hidrocarbonetos Clorados , Praguicidas , Bifenilos Policlorados , Idoso , Humanos , Pessoa de Meia-Idade , Cognição , Exposição Ambiental/análise , Poluentes Ambientais/toxicidade , Hexaclorobenzeno , Hidrocarbonetos Clorados/toxicidade , Indígenas Norte-Americanos , Mirex , Praguicidas/toxicidade , Bifenilos Policlorados/toxicidadeRESUMO
Infant exposure to per/polyfluoroalkyl compounds is associated with immune disruption. We examined associations between neonatal concentrations of perflurooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) and immunoglobulin (Ig) isotype profiles in a prospective cohort of infants. We measured Ig isotypes, including IgA, IgE, IgM and the IgG subclasses IgG1, IgG2, IgG3, and IgG4, and PFOA and PFOS in newborn dried bloodspots from N = 3175 infants in the Upstate KIDS Study (2008-2010). We examined the association between newborn Ig isotype levels and individual PFOS and PFOA concentrations using mixed effects regression models with a random intercept to account for twins among study participants. We assessed the joint effect PFOA and PFOS with quantile-based g-computation on all singletons and one randomly selected twin (N = 2901), with Ig categorized as above or below median value. Models were adjusted for infant sex, and maternal pre-pregnancy body mass index, race, parity, age and infertility treatment. In adjusted models, PFOA was inversely associated with IgE (coefficient = -0.12 per unit increase in PFOA, 95% CI: -0.065, -0.17), whereas IgG2, IgM, and IgA were positively associated with PFOA (coefficient for IgG2 = 0.22, 95% CI: 0.15, 0.27; coefficient for IgM = 0.11, 95% CI: 0.08, 0.15; and coefficient for IgA = 0.15, 95% CI: 0.07, 0.18). There was no relation between PFOS and Ig isotypes. Analysis of the joint effect of PFOA and PFOS showed an OR of 1.2 (95% CI: 1.04, 1.36) for IgA and OR of 1.12 (95% CI: 1.00, 1.24) for IgG2 levels above the median for every quartile increase. PFOA levels were significantly associated with elevated IgA, IgM, IgG2, and reduced levels of IgE in single-pollutant models. A small but significant joint effect of PFOA and PFOS was observed. Our results suggest that early exposure to PFOA and PFOS may disrupt neonatal immunoglobulin levels.
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Ácidos Alcanossulfônicos , Fluorocarbonos , Caprilatos , Feminino , Humanos , Imunoglobulina A , Imunoglobulina E , Imunoglobulina G , Imunoglobulina M , Lactente , Recém-Nascido , Gravidez , Estudos ProspectivosRESUMO
BACKGROUND: New Jersey (NJ) Safe Schools Program, primarily funded by the NJ Department of Education, has aims concerning safety and health including helping to alleviate harassment, intimidation, and bullying (HIB) in secondary school because HIB can affect learning. We evaluated officially reported adolescent HIB total incidents and estimated rates in NJ public city and county school districts for the 2011-2016 school years. METHODS: A cross-sectional observational study using population-based state-reported public data. We calculated point prevalence and incidence rates for K-12 students in 22 public city school districts, students in 21 career-technical-vocational education (CTE) school districts, and 8 special services school districts during 2011-2016. RESULTS: HIB is prevalent in NJ school classrooms. HIB comprised ≥75% of total officially reported in-school violence-related incidents in a given school year. Rates per 100 enrollees of total officially reported incidents for the 5-year period of 2011-2016 was highest in special services school districts (5.00; 95% confidence interval [CI]: 4.67, 5.34) followed by CTE districts (1.94; 95% CI: 1.86, 2.01), and lowest in city districts (1.46; 95% CI: 1.44, 1.48). The special services school district also had the highest rates per year and the 5-year period. CONCLUSIONS: Data analyses suggested ideas for further research and improvements for school HIB incident reports. Policies and programs could remedy issues observed in state secondary school classrooms. Best practices within districts and schools can help protect students from HIB and promote safety, health, learning, and maturation.
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Bullying , Instituições Acadêmicas , Violência , Adolescente , Estudos Transversais , Humanos , New Jersey/epidemiologiaRESUMO
INTRODUCTION: Adolescents engaging in school-sponsored work experiences may be at risk of injury due to factors such as inexperience. This article examines trends in 20â¯years of reported injuries among New Jersey (NJ) adolescents engaging in school-sponsored work experiences, and compares a transition from paper to online reporting format. METHODS: New Jersey requires reporting of injuries occurring during school-sponsored work experiences to the NJ Department of Education. Injuries reported by NJ schools from 1999 to 2018 (nâ¯=â¯2,119) were examined; incidence rates for 2008 to 2018 (nâ¯=â¯743) were calculated using publicly available NJ Department of Education enrollment data for the denominator, including for specific groups of students: career and technical education; special healthcare needs. RESULTS: A downward trend in reported injuries in NJ schools was observed. However, the year online reporting became required by code (2013), an increase of nearly 50% was seen from 2012 (59-89), followed by a decline in reported incidents 2014 to 2018 (meanâ¯=â¯65, range 76 down to 47). Injury rate trends over time paralleled those of reported incidents. CONCLUSIONS: This study suggested worker safety and public health benefits of improvements from State of NJ code required training programs and online injury surveillance report form. Practical Applications: One potential method to address the safety and health of adolescents engaging in work experiences is the use of online reporting forms, to aid in surveillance efforts, coupled with occupational safety and health training specifically geared toward teachers and administrators who both supervise young, relatively inexperienced and vulnerable workers and who make relatively frequent worksite visits. Incorporation of specific details of the instructions on the use of a reporting form into required trainings, in addition to providing a clear, accessible guidance manual online, could further help improve youth worker safety surveillance efforts.
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Saúde Ocupacional/tendências , Segurança/estatística & dados numéricos , Local de Trabalho/estatística & dados numéricos , Ferimentos e Lesões/epidemiologia , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , New Jersey/epidemiologia , Instituições Acadêmicas , Ferimentos e Lesões/classificação , Ferimentos e Lesões/etiologia , Adulto JovemRESUMO
BACKGROUND: There is an increasing concern over adolescent concussions in sports due to risks of long-term negative effects. This study analyzed data over three school years on reported concussion incidence rates by season, high school grade levels and gender, and reported symptoms by school nurses versus athletic trainers, from New Jersey student-athlete concussion data available from an online school-based surveillance system. METHODS: School nurses and athletic trainers reported 300 concussions within five days from when each occurred over three school years, 2015-2018, in team sports and physical education in New Jersey high schools. Analysis was further conducted on symptoms and number of symptoms reported by school nurses versus school athletic trainers for each documented student-athlete concussion. Estimated concussion incidence rates were calculated using state agency verified school enrollment data. FINDINGS: Concussions most commonly occurred during fall, followed by spring, then winter. Concussion incidence rates ranged from 6.3/1000 (4.99, 7.55) - 9.1/1000 (7.27, 10.98) students over the three school years of the study. Athletic trainers completed 86% of the reports while nurses completed 11% (position or title of 3%, or n = 7, were not disclosed); the values were similar when considering only fall pre-season and regular season sports (88, 10, 2%, respectively). On average, across the three school years, athletic trainers reported about 3.5 symptoms per report while nurses reported 2.7 (values in fall seasons only were 3.7 and 3.1, respectively.) CONCLUSIONS: Certified athletic trainers, compared to school nurses, more often completed concussion report forms and reported more symptoms per injured student, perhaps due partly to closer contact and immediate care provided after injury. Additionally, this study had a higher concussion incidence rate during fall sports seasons compared to winter and spring. Future research can further improve our understanding of concussions among adolescent student-athletes to better inform concussion identification, management and recovery protocols.
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Bee populations are currently undergoing severe global declines driven by the interactive effects of a number of factors. Ongoing urbanisation has the potential to exacerbate bee declines, unless steps are taken to ensure appropriate floral resources are available. Sown wildflower strips are one way in which floral resources can be provided to urban bees. However, the use of these strips by pollinators in urban environments remains little studied. Here, we employ pollen metabarcoding of the rbcL gene to compare the foraging patterns of different bee species observed using urban sown wildflower strips in July 2016, with a goal of identifying which plant species are most important for bees. We also demonstrate the use of a non-destructive method of pollen collection. Bees were found to forage on a wide variety of plant genera and families, including a diverse range of plants from outside the wildflower plots, suggesting that foragers visiting sown wildflower strips also utilize other urban habitats. Particular plants within the wildflower strips dominated metabarcoding data, particularly Papaver rhoeas and Phacelia tanacetifolia. Overall, we demonstrate that pollinators observed in sown wildflower strips use certain sown foodplants as part of a larger urban matrix.
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Understanding which flowers honey bees (Apis mellifera) use for forage can help us to provide suitable plants for healthy honey bee colonies. Accordingly, honey DNA metabarcoding provides a valuable tool for investigating pollen and nectar collection. We investigated early season (April and May) floral choice by honey bees provided with a very high diversity of flowering plants within the National Botanic Garden of Wales. There was a close correspondence between the phenology of flowering and the detection of plants within the honey. Within the study area there were 437 genera of plants in flower during April and May, but only 11% of these were used. Thirty-nine plant taxa were recorded from three hives but only ten at greater than 1%. All three colonies used the same core set of native or near-native plants, typically found in hedgerows and woodlands. The major plants were supplemented with a range of horticultural species, with more variation in plant choice between the honey bee colonies. We conclude that during the spring, honey bees need access to native hedgerows and woodlands to provide major plants for foraging. Gardens provide supplementary flowers that may increase the nutritional diversity of the honey bee diet.
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Abelhas/fisiologia , Comportamento Animal , Código de Barras de DNA Taxonômico/métodos , Plantas/classificação , Animais , DNA de Plantas/genética , Flores/classificação , Flores/genética , Mel , Plantas/genética , Estações do Ano , Análise de Sequência de DNARESUMO
Fifty-three RNA duplexes containing two single nucleotide bulge loops were optically melted in 1 M NaCl in order to determine the thermodynamic parameters ΔH°, ΔS°, ΔG°37, and TM for each duplex. Because of the large number of possible combinations and lack of sequence effects observed previously, we limited our initial investigation to adenosine bulges, the most common naturally occurring bulge. For example, the following duplexes were investigated: 5'GGCAXYAGGC/3'CCG YX CCG, 5'GGCAXY GCC/3'CCG YXACGG, and 5'GGC XYAGCC/3'CCGAYX CGG. The identity of XY (where XY are Watson-Crick base pairs) and the total number of base pairs in the terminal and central stems were varied. As observed for duplexes with a single bulge loop, the effect of the two bulge loops on duplex stability is primarily influenced by non-nearest neighbor interactions. In particular, the stability of the stems influences the destabilization of the duplex by the inserted bulge loops. The model proposed to predict the influence of multiple bulge loops on duplex stability suggests that the destabilization of each bulge is related to the stability of the adjacent stems. A database of RNA secondary structures was examined to determine the naturally occurring abundance of duplexes containing multiple bulge loops. Of the 2000 examples found in the database, over 65% of the two bulge loops occur within 3 base pairs of each other. A database of RNA three-dimensional structures was examined to determine the structure of duplexes containing two single nucleotide bulge loops. The structures of the bulge loops are described.
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Sequências Repetidas Invertidas , RNA de Cadeia Dupla/química , RNA Ribossômico 23S/química , Pareamento de Bases , Bases de Dados de Ácidos Nucleicos , Modelos Moleculares , Conformação de Ácido Nucleico , Estabilidade de RNA , TermodinâmicaRESUMO
OBJECTIVE: To describe in detail the radiographic appearance of ossified ungular cartilages in horses and to evaluate the usefulness of a flexed dorsolateral-palmaromedial oblique (flexed oblique) radiographic view in evaluating the ungular cartilages. DESIGN: Retrospective case series. Sample-Radiographs of 1,255 front feet of horses. PROCEDURES: Ossification of the ungular cartilages was graded during evaluation of radiographs on a scale from 0 to 5; feet with cartilages with an ossification grade ≥ 2 were included (386 feet [271 horses]). The shape (straight, curved outward or inward, and dorsopalmar extension of ossification) was determined. The view on which abnormalities were best identified was documented. Abnormalities of the compact bone, radiopacity, trabecular architecture, compactospongious demarcation, and presence of radiolucent lines were recorded; grouped as modeling, adaptive changes, or both; compared with ossification grade, separate centers of ossification, mediolateral symmetry of ossification, shape, cartilage (medial or lateral), and foot (left or right); and tested for significant associations. RESULTS: Fractures (n = 35) were most common in feet with cartilages with an ossification grade of 4 (18) or 5 (17) and were best identified in flexed oblique images, compared with more commonly recommended images. Multivariable logistic regression showed a significant positive association of ossification grade with modeling or adaptive changes; feet with cartilages with an ossification grade of 4 (OR, 11.59; 95% CI, 6.52 to 20.60) or 5 (OR, 72.90; 95% CI, 25.32 to 209.90) were more likely than those with an ossification grade of 2 or 3 to have modeling or adaptive changes. Abnormally shaped cartilages were more likely to have modeling or adaptive changes, compared with normally shaped cartilages (OR, 4.90; 95% CI, 1.94 to 12.42). CONCLUSIONS AND CLINICAL RELEVANCE: Extensive ossification and the presence of inward or outward curvature as well as palmar curvature or a bulbous shape were significant risk factors for modelling and adaptive changes. Flexed oblique images provided clinically useful information, including detection of abnormal shape and fractures, that may not be evident on other currently recommended images. Such images are recommended for complete radiographic appraisal of ossified ungular cartilages of the foot in horses.
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Doenças das Cartilagens/veterinária , Doenças do Pé/veterinária , Doenças dos Cavalos/diagnóstico por imagem , Ossificação Heterotópica/veterinária , Animais , Ligamentos Colaterais/patologia , Feminino , Doenças do Pé/diagnóstico por imagem , Doenças do Pé/patologia , Doenças dos Cavalos/patologia , Cavalos , Masculino , Ossificação Heterotópica/diagnóstico por imagem , Ossificação Heterotópica/patologia , Radiografia , Estudos RetrospectivosRESUMO
When there is conspicuous underexploitation of a limited resource, it is worth asking, what mechanisms allow presumably valuable resources to be left unused? Evolutionary biologists have generated a wide variety of hypotheses to explain this, ranging from interdemic group selection to selfishly prudent individual restraint. We consider a situation in which, despite high intraspecific competition, individuals leave most of a key resource unexploited. The parasitic wasp that does this finds virtually all host egg clusters in a landscape but parasitizes only about a third of the eggs in each and then leaves a deterrent mark around the cluster. We first test-and reject-a series of system-specific simple constraints that might limit full host exploitation, such as asynchronous maturation of host eggs. We then consider classical hypotheses for the evolution of restraint. Prudent predation and bet-hedging fail as explanations because the wasp lives as a large, well-mixed population. Additionally, we find no individual benefits to the parasitoid of developing in a sparsely parasitized host nest. However, an optimal foraging model, including empirically measured costs of superparasitism and hyperparasitism, can explain through individual selection both the consistently low rate of parasitism and deterrent marking.
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Borboletas/parasitologia , Vespas/fisiologia , Comunicação Animal , Animais , Comportamento Animal , Comportamento Competitivo , Feminino , Modelos Teóricos , OviposiçãoRESUMO
Consumer-resource interactions are fundamental components of ecological communities. Classic features of consumer-resource models are that temporal dynamics are often cyclic, with a »-period lag between resource and consumer population peaks. However, there are few published empirical examples of this pattern. Here, we show that many published examples of consumer-resource cycling show instead patterns indicating eco-evolutionary dynamics. When prey evolve along a trade-off between defence and competitive ability, two-species consumer-resource cycles become longer and antiphase (half-period lag, so consumer maxima coincide with minima of the resource species). Using stringent criteria, we identified 21 two-species consumer-resource time series, published between 1934 and 1997, suitable to investigate for eco-evolutionary dynamics. We developed a statistical method to probe for a transition from classic to eco-evolutionary cycles, and find evidence for eco-evolutionary type cycles in about half of the studies. We show that rapid prey evolution is the most likely explanation for the observed patterns.
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Evolução Biológica , Modelos Biológicos , Animais , Ecossistema , Cadeia AlimentarRESUMO
In the beeswax combs of honey bees, the cells of brood, pollen, and honey have a consistent spatial pattern that is sustained throughout the life of a colony. This spatial pattern is believed to emerge from simple behavioral rules that specify how the queen moves, where foragers deposit honey/pollen and how honey/pollen is consumed from cells. Prior work has shown that a set of such rules can explain the formation of the allocation pattern starting from an empty comb. We show that these rules cannot maintain the pattern once the brood start to vacate their cells, and we propose new, biologically realistic rules that better sustain the observed allocation pattern. We analyze the three resulting models by performing hundreds of simulation runs over many gestational periods and a wide range of parameter values. We develop new metrics for pattern assessment and employ them in analyzing pattern retention over each simulation run. Applied to our simulation results, these metrics show alteration of an accepted model for honey/pollen consumption based on local information can stabilize the cell allocation pattern over time. We also show that adding global information, by biasing the queen's movements towards the center of the comb, expands the parameter regime over which pattern retention occurs.
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Abelhas/fisiologia , Comportamento Animal , Análise de Variância , Animais , Simulação por Computador , Mel , Modelos Biológicos , Pólen/citologia , Reprodutibilidade dos Testes , Fatores de TempoRESUMO
Feedbacks between ecological and evolutionary change may play important roles in community and ecosystem functioning, but a complete eco-evolutionary feedback loop has not been demonstrated at the community level, and we know little about molecular mechanisms underlying this kind of eco-evolutionary dynamics. In predator-prey (rotifer-alga) microcosms, cyclical changes in predator abundance generated fluctuating selection for a heritable prey defence trait, cell clumping. Predator population growth was affected more by prey evolution than by changes in prey abundance, and changes in predator abundance drove further prey evolution, completing the feedback loop. Within a predator-prey cycle, genes up-regulated as clumping declined were down-regulated as clumping increased, and vice-versa. Genes changing most in expression tended to be associated with defence or its cost. Expression patterns of individual genes differed greatly between consecutive cycles (often reversing direction), suggesting that a particular phenotype may be produced by several (perhaps many) different gene transcription pathways.