Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 194
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Neuroimage ; 269: 119933, 2023 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-36754124

RESUMO

We spend much our lives interacting with others in various social contexts. Although we deal with this myriad of interpersonal exchanges with apparent ease, each one relies upon a broad array of sophisticated cognitive processes. Recent research suggests that the cognitive operations supporting interactive behaviour are themselves underpinned by several canonical functional brain networks (CFNs) that integrate dynamically with one another in response to changing situational demands. Dynamic integrations among these CFNs should therefore play a pivotal role in coordinating interpersonal behaviour. Further, different types of interaction should present different demands on cognitive systems, thereby eliciting distinct patterns of dynamism among these CFNs. To investigate this, the present study performed functional magnetic resonance imaging (fMRI) on 30 individuals while they interacted with one another cooperatively or competitively. By applying a novel combination of analytical techniques to these brain imaging data, we identify six states of dynamic functional connectivity characterised by distinct patterns of integration and segregation among specific CFNs that differ systematically between these opposing types of interaction. Moreover, applying these same states to fMRI data acquired from an independent sample engaged in the same kinds of interaction, we were able to classify interpersonal exchanges as cooperative or competitive. These results provide the first direct evidence for the systematic involvement of CFNs during social interactions, which should guide neurocognitive models of interactive behaviour and investigations into biomarkers for the interpersonal dysfunction characterizing many neurological and psychiatric disorders.


Assuntos
Transtornos Mentais , Interação Social , Humanos , Encéfalo/fisiologia , Mapeamento Encefálico , Imageamento por Ressonância Magnética/métodos
2.
Neuroimage ; 228: 117697, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33385556

RESUMO

Verbal communication relies heavily upon mutual understanding, or common ground. Inferring the intentional states of our interaction partners is crucial in achieving this, and social neuroscience has begun elucidating the intra- and inter-personal neural processes supporting such inferences. Typically, however, neuroscientific paradigms lack the reciprocal to-and-fro characteristic of social communication, offering little insight into the way these processes operate online during real-world interaction. In the present study, we overcame this by developing a "hyperscanning" paradigm in which pairs of interactants could communicate verbally with one another in a joint-action task whilst both undergoing functional magnetic resonance imaging simultaneously. Successful performance on this task required both interlocutors to predict their partner's upcoming utterance in order to converge on the same word as each other over recursive exchanges, based only on one another's prior verbal expressions. By applying various levels of analysis to behavioural and neuroimaging data acquired from 20 dyads, three principal findings emerged: First, interlocutors converged frequently within the same semantic space, suggesting that mutual understanding had been established. Second, assessing the brain responses of each interlocutor as they planned their upcoming utterances on the basis of their co-player's previous word revealed the engagement of the temporo-parietal junctional (TPJ), precuneus and dorso-lateral pre-frontal cortex. Moreover, responses in the precuneus were modulated positively by the degree of semantic convergence achieved on each round. Second, effective connectivity among these regions indicates the crucial role of the right TPJ in this process, consistent with the Nexus model. Third, neural signals within certain nodes of this network became aligned between interacting interlocutors. We suggest this reflects an interpersonal neural process through which interactants infer and align to one another's intentional states whilst they establish a common ground.


Assuntos
Encéfalo/fisiologia , Comportamento Social , Interação Social , Comportamento Verbal/fisiologia , Adulto , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética , Masculino , Neuroimagem/métodos , Adulto Jovem
3.
Psychol Res ; 84(4): 1139-1156, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30324265

RESUMO

This study investigated the structure of social cognition, and how it is influenced by personality; specifically, how various socio-cognitive capabilities, and the pattern of inter-relationships and co-dependencies among them differ between divergent personality styles. To measure social cognition, a large non-clinical sample (n = 290) undertook an extensive battery of self-report and performance-based measures of visual perspective taking, imitative tendencies, affective empathy, interoceptive accuracy, emotion regulation, and state affectivity. These same individuals then completed the Personality Styles and Disorders Inventory. Latent Profile Analysis revealed two dissociable personality profiles that exhibited contrasting cognitive and affective dispositions, and multivariate analyses indicated further that these profiles differed on measures of social cognition; individuals characterised by a flexible and adaptive personality profile expressed higher action orientation (emotion regulation) compared to those showing more inflexible tendencies, along with better visual perspective taking, superior interoceptive accuracy, less imitative tendencies, and lower personal distress and negativity. These characteristics point towards more efficient self-other distinction, and to higher cognitive control more generally. Moreover, low-level cognitive mechanisms served to mediate other higher level socio-emotional capabilities. Together, these findings elucidate the cognitive and affective underpinnings of individual differences in social behaviour, providing a data-driven model that should guide future research in this area.


Assuntos
Empatia , Individualidade , Comportamento Social , Percepção Social , Cognição/fisiologia , Emoções/fisiologia , Feminino , Humanos , Masculino , Personalidade , Adulto Jovem
4.
J Dairy Sci ; 103(1): 714-722, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31629521

RESUMO

The aim of this study was to objectively assess, using an automated behavioral monitoring system, any behavioral differences between primiparous and multiparous cows before calving, and to quantify any behavioral differences between assisted (dystocic) and unassisted (eutocic) calvings. Data were collected from 32 multiparous and 12 primiparous Holstein dairy cattle to describe normal calving behavior and parity differences. To quantify behavior related to calving difficulty, the data from 14 animals that had dystocia at calving were matched to cows that had an eutocic calving based on parity, locomotion score, calf breed, calf sex, month, and year of calving. An IceQube (IceRobotics Ltd., South Queensferry, United Kingdom) was fitted to the right hind leg of cows 4 wk before their expected calving date. Data for lying time, standing time, number of steps, motion index (total motion), and the total number of standing and lying bouts (postural transitions) were automatically collected and summed into 15-min blocks. Behavioral variables were summarized into 2-h periods and 24-h periods before analyses. Mixed-effect models were used to analyze cow behavior in the last 4 d before calving (d -4 to -1), and on the day of calving. In the 4 d before calving, compared with multiparous cows, primiparous cows lay down an average 2.8 h/d less, had 9.1 more postural transitions/d (37.7 ± 1.2 vs. 27.6 ± 0.7), walked 172 more steps/d, and had a higher motion index (2,673.2 vs. 1,981.5 units/d). There was an effect of 2-h period on all behavioral variables on the day of calving. No indicator of calving difficulty was found on the day of calving, nor the days leading up to calving. These findings suggest that parity should be considered when predicting the day of calving, and changes in cow behavior on the day of calving could be used to identify calving cows, and to predict the time of calving.


Assuntos
Comportamento Animal , Doenças dos Bovinos/fisiopatologia , Distocia/veterinária , Paridade , Animais , Bovinos , Distocia/fisiopatologia , Feminino , Lactação , Locomoção , Parto , Gravidez
5.
J Dairy Sci ; 103(11): 10604-10613, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32896414

RESUMO

The aim of this study was to use an automated behavior-monitoring system to objectively assess the association between lying and activity behavior in the precalving, calving, and postcalving periods between multiparous and primiparous cows with (1) normocalcemia, (2) subclinical hypocalcemia, or (3) clinical hypocalcemia at calving. Behavioral data and blood serum samples were collected from 51 multiparous and 21 primiparous Holstein dairy cattle. Blood samples from the coccygeal vein were taken within 24 h of calving, and serum was analyzed to measure total calcium concentration. Cows were classified into one of 3 categories: normocalcemia (serum calcium concentration ≥ 2.0 mmol/L), subclinical hypocalcemia (serum calcium concentration < 2.0 mmol/L, absence of clinical signs), and clinical hypocalcemia (clinical signs and successful treatment). An activity sensor was fitted to the right hind leg of cows 3 wk before their expected calving date. Data for lying time, standing time, number of steps, and the total number of standing and lying bouts (postural transitions) were automatically collected and summed into 15-min blocks. Behavioral variables were summarized into 2-h and 24-h periods before analyses. Mixed effect models were used to analyze cow behavior in the entire 14 d before calving (d -14 to -1), on the day of calving, and the entire 21 d postcalving (d 1 to 21). In the precalving period, multiparous cows with normocalcemia had fewer postural transitions (18.5 ± 6.9 no./d) compared with cows with subclinical hypocalcemia (23.5 ± 8.0 no./d) and clinical hypocalcemia (23.5 ± 8.6 no./d). However, there was no association between blood calcium status on lying time (min/d) or step count (no./d) for multiparous cows. For primiparous cows, the step count of cows with subclinical hypocalcemia remained constant across the period, and the step count of cows with normocalcemia decreased from 842.8 steps/d on d -14 to 427.5 steps/d on d -1. Postpartum cows with clinical hypocalcemia were less active (fewer steps) and spent 88 min/d (1.5 h) and 125 min/d (2.1 h) more time lying down compared with cows with subclinical hypocalcemia and normocalcemia, respectively. This shows that clinical hypocalcemia is associated with significant long-lasting behavioral effects on cows during the critical postpartum period.


Assuntos
Comportamento Animal , Cálcio/sangue , Doenças dos Bovinos/sangue , Bovinos/fisiologia , Hipocalcemia/veterinária , Período Pós-Parto , Animais , Bovinos/sangue , Feminino , Hipocalcemia/sangue , Lactação , Paridade , Gravidez
6.
J Phys Chem A ; 122(3): 780-787, 2018 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-29250947

RESUMO

A high-speed, high-sensitivity and compact two-dimensional infrared (2D-IR) spectrometer based on 100 kHz Yb:KGW regenerative amplifier technology is described and demonstrated. The setup is three color, using an independent pump OPA and two separately tunable probe OPAs. The spectrometer uses 100 kHz acousto-optic pulse shaping on the pump beam for rapid 2D-IR acquisitions. The shot-to-shot stability of the laser system yields excellent signal-to-noise figures (∼10 µOD noise on 5000 laser shots). We show that the reduced bandwidth of the Yb:KGW amplifiers in comparison with conventional Ti:sapphire systems does not compromise the ability of the setup to generate high-quality 2D-IR data. Instrument responses of <300 fs are demonstrated and 2D-IR data presented for several systems of interest to physical chemists, showing spectral diffusion in NaSCN, amide I and II bands of a ß sheet protein and DNA base-pair-backbone couplings. Overall, the increased data acquisition speed, intrinsic stability, and robustness of the Yb:KGW lasers are a significant step forward for 2D-IR spectroscopy.

7.
J Dairy Sci ; 100(7): 5449-5461, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28527799

RESUMO

The aims of the present study were to evaluate the effects of live yeast supplementation (Vistacell MUCL 39855, AB Vista, Marlborough, UK) on performance, rumination time, and rumen pH on dairy cows in commercial farm environments. Three trials were carried out, the trials lasted 12 (trial 1), 15 (trial 2), and 19 wk (trial 3). In each trial, 14 multiparous Holstein dairy cows were allocated to 2 groups that received (trial 1) a standard diet plus yeast, (trial 2) an acidogenic diet plus yeast, and (trial 3) grazing pasture plus yeast. Milk production, milk chemical characteristics, body weight and body condition score, rumination time, and rumen pH were monitored for each group throughout the 3 trials. No statistically significant differences were observed in any of the 3 trials for any of the recorded variables. In contrast, an effect of time (period or days in milk) on rumen pH was observed in all 3 of the trials, as time spent under the acidotic thresholds increased across the experimental periods; however the differences were not associated with live yeast supplementation. No effect of live yeast supplementation was observed in any of the 3 trials reported. Further research should include studies on animals at different stages of lactation (with emphasis on transition period and early lactation), consuming more challenging diets (higher level of inclusion of concentrates or starch), or under different environments such as grazing of succulent forages. Such studies might be required to elucidate any possible effect of live yeast supplementation of dairy cows when the rumen environment is under challenge.


Assuntos
Dieta/veterinária , Leite/metabolismo , Fermento Seco/administração & dosagem , Fenômenos Fisiológicos da Nutrição Animal , Animais , Peso Corporal , Bovinos , Comércio , Fazendas , Feminino , Concentração de Íons de Hidrogênio , Lactação , Leite/química , Rúmen/química , Rúmen/metabolismo , Fatores de Tempo
8.
J Dairy Sci ; 98(3): 1750-8, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25622871

RESUMO

Automated systems for monitoring the behavior of cows have become increasingly important for management routines and for monitoring health and welfare. In the past few decades, various devices that record rumination have been developed. The aim of the present study was to compare rumination activity measured with a commercially available rumination collar (RC) against that obtained by direct visual observations and analysis of video recordings in commercial dairy cows. Rumination time from video recordings was recorded by a trained observer. To assess observer reliability, data were recorded twice, and the duration of recorded behaviors was very similar and highly correlated between these 2 measurements (mean=39±4 and 38±4 min/2 h). Measurements of rumination time obtained with RC when compared with analysis of video recordings and direct observations were variable: RC output was significantly positively related to observed rumination activity when dealing with animals housed indoors (trial 1 video recordings: slope=1.02, 95% CI=0.92-1.12), and the limits of agreement method (LoA) showed differences (in min per 2-h block) to be within -26.92 lower and 24.27 upper limits. Trial 1 direct observations: slope=1.08, 95% CI=0.62-1.55, and the LoA showed differences to be within -28.54 lower and 21.98 upper limits. Trial 2: slope=0.93, 95% CI=0.64-1.23, and the LoA showed differences to be within -32.56 lower and 19.84 upper limits. However, the results were poor when cows were outside grazing grass (trial 3: slope=0.57, 95% CI=0.13-1.02, and the LoA showed differences to be within wider limits -51.16 lower and 53.02 upper). Our results suggest that RC can determine rumination activity and are an alternative to visual observations when animals are housed indoors. However, they are not an alternative to direct observations with grazing animals on pasture and its use is not advisable until further research and validation are carried out.


Assuntos
Bovinos/fisiologia , Gravação em Vídeo/métodos , Animais , Automação , Indústria de Laticínios/métodos , Feminino , Distribuição Aleatória , Reprodutibilidade dos Testes , Gravação em Vídeo/instrumentação
9.
Phys Rev Lett ; 113(20): 207801, 2014 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-25432055

RESUMO

We demonstrate that local orientational ordering in a liquid can be observed in the decay of the vibrational anisotropy caused by resonant transfer of vibrational excitations between its constituent molecules. We show that the functional form of this decay is determined by the (distribution of) angles between the vibrating bonds of the molecules between which energy transfer occurs, and that the initial drop in the decay reflects the average angle between nearest neighbors. We use this effect to observe the difference in local orientational ordering in the two hydrogen-bonded liquids ethanol and N-methylacetamide.

10.
Nat Genet ; 4(4): 393-7, 1993 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-8401588

RESUMO

The molecular analysis of a specific CAG repeat sequence in the Huntington's disease gene in 440 Huntington's disease patients and 360 normal controls reveals a range of 30-70 repeats in affected individuals and 9-34 in normals. We find significant negative correlations between the number of repeats on the HD chromosome and age at onset, regardless of sex of the transmitting parent, and between the number of repeats on the normal paternal allele and age at onset in individuals with maternally transmitted disease. This effect of the normal paternal allele may account for the weaker age at onset correlation between affected sib pairs with disease of maternal as opposed to paternal origin and suggests that normal gene function varies because of the size of the repeat in the normal range and a sex-specific modifying effect.


Assuntos
Variação Genética , Doença de Huntington/genética , Sequências Repetitivas de Ácido Nucleico , Adolescente , Adulto , Fatores Etários , Idoso , Sequência de Bases , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Oligodesoxirribonucleotídeos , Fenótipo , Reação em Cadeia da Polimerase , Valores de Referência
11.
J Small Anim Pract ; 64(11): 687-695, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37770103

RESUMO

OBJECTIVES: To investigate the association between body mass and hypotension during general anaesthesia in dogs undergoing surgical and diagnostic procedures within a referral hospital. MATERIALS AND METHODS: Retrospective evaluation of the anaesthetic records of 1789 dogs was performed. Data on signalment, anaesthetic protocol and physiological variables, including mean arterial pressure, were collected. A multivariable generalised linear model was used to identify associations between explanatory variables, including body mass, and hypotension. RESULTS: In the population studied, increasing body mass (per 10 kg) was significantly associated with decreasing odds of hypotension (odds ratio 0.68; 95% confidence interval: 0.60 to 0.77). Additional variables associated with a decreased odds of hypotension were pre-anaesthetic medication with alpha-2 agonists (odds ratio 0.63; 95% confidence interval 0.48 to 0.82) and increased body temperature (per 1°C) during general anaesthesia (odds ratio 0.77; 95% confidence interval 0.67 to 0.88). Brachycephaly (odds ratio 1.72; 95% confidence interval 1.25 to 2.38), ASA physical status classification >3 (odds ratio 2.03; 95% confidence interval 1.16 to 3.56), undergoing a surgical procedure (versus diagnostic) (odds ratio 1.57; 95% confidence interval 1.10 to 2.23) and bradycardia (odds ratio 1.37; 95% confidence interval 1.05 to 1.80) were independently associated with increased odds of hypotension. CLINICAL SIGNIFICANCE: Dogs of lower body mass and brachycephalic breeds may be at higher risk of hypotension during general anaesthesia or alternatively represent subpopulations in which accurate blood pressure measurement presents a greater challenge. Monitoring blood pressure accurately in these groups requires particular attention and provisions for treating hypotension should be readily accessible.


Assuntos
Anestésicos , Doenças do Cão , Hipotensão , Cães , Animais , Estudos Retrospectivos , Anestesia Geral/efeitos adversos , Anestesia Geral/veterinária , Hipotensão/veterinária , Doenças do Cão/cirurgia
12.
Gene Ther ; 18(10): 996-1005, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21512505

RESUMO

We use both large and small animal models in our pre-clinical evaluation of gene transfer agents (GTAs) for cystic fibrosis (CF) gene therapy. Here, we report the use of a large animal model to assess three non-viral GTAs: 25 kDa-branched polyethyleneimine (PEI), the cationic liposome (GL67A) and compacted DNA nanoparticle formulated with polyethylene glycol-substituted lysine 30-mer. GTAs complexed with plasmids expressing human cystic fibrosis transmembrane conductance regulator (CFTR) complementary DNA were administered to the sheep lung (n=8 per group) by aerosol. All GTAs gave evidence of gene transfer and expression 1 day after treatment. Vector-derived mRNA was expressed in lung tissues, including epithelial cell-enriched bronchial brushing samples, with median group values reaching 1-10% of endogenous CFTR mRNA levels. GL67A gave the highest levels of expression. Human CFTR protein was detected in small airway epithelial cells in some animals treated with GL67A (two out of eight) and PEI (one out of eight). Bronchoalveolar lavage neutrophilia, lung histology and elevated serum haptoglobin levels indicated that gene delivery was associated with mild local and systemic inflammation. Our conclusion was that GL67A was the best non-viral GTA currently available for aerosol delivery to the sheep lung, led to the selection of GL67A as our lead GTA for clinical trials in CF patients.


Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística/genética , Fibrose Cística/terapia , Técnicas de Transferência de Genes , Terapia Genética/métodos , Lipossomos/administração & dosagem , Nanopartículas/administração & dosagem , Polietilenoimina/administração & dosagem , Administração por Inalação , Animais , Fibrose Cística/genética , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , DNA Complementar/administração & dosagem , DNA Complementar/genética , Humanos , Polietilenoglicóis , RNA Mensageiro/metabolismo , Ovinos
13.
Exp Lung Res ; 37(9): 519-35, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21895444

RESUMO

Understanding the fundamental processes involved in repairing the airway wall following injury is fundamental to understanding the way in which these processes are perturbed during disease pathology. Indeed complex diseases such as asthma and chronic obstructive pulmonary disease (COPD) have at their core evidence of airway wall remodeling processes that play a crucial functional role in these diseases. The authors sought to understand the dynamic cellular events that occur during bronchial airway epithelial repair in sheep. The injury was induced by endobronchial brush biopsy (BBr), a process that causes epithelial débridement and induces a consequential repair process. In addition, the current experimental protocol allowed for the time-dependent changes in airway wall morphology to be studied both within and between animals. The initial débridement was followed by evidence of dedifferentiation in the intact epithelium at the wound margins, followed by proliferation of cells both within the epithelium and in the deeper wall structures, notably in association with the submucosal glands and smooth muscle bundles. Seven days after injury, although the airway wall was thickened at the site of damage, the epithelial layer was intact, with evidence of redifferentiation. These studies, in demonstrating broad agreement with previous studies in small animals, indicate the wider relevance of this system as a comparative model and should provide a solid basis upon which to further characterize the critical cellular and molecular interactions that underlie both effective restitution and pathological repair.


Assuntos
Remodelação das Vias Aéreas , Brônquios/fisiologia , Regeneração , Mucosa Respiratória/fisiologia , Análise de Variância , Animais , Biópsia , Brônquios/lesões , Brônquios/patologia , Feminino , Antígeno Ki-67/metabolismo , Lesão Pulmonar/metabolismo , Lesão Pulmonar/patologia , Masculino , Reação do Ácido Periódico de Schiff , Mucosa Respiratória/lesões , Mucosa Respiratória/patologia , Ovinos
14.
Animal ; 15(4): 100176, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33637437

RESUMO

Given the economic impact of gastrointestinal nematode infection on livestock farming worldwide, and increasing anthelmintic resistance, it is imperative to develop practical, efficient and sustainable control strategies. Targeted selective treatment (TST), whereby anthelmintic treatments are administered to animals individually, based on selection criteria such as weight gain, has been shown to successfully maintain animal productivity whilst reducing the selection pressure for anthelmintic resistance and the economic cost of treatment in experimental and commercial settings. Despite the benefits of the TST approach, the equipment and time required to monitor animals individually make this strategy unsuitable for some farming enterprises. The sentinel group approach aims to maintain the benefits observed using TST whilst reducing these requirements. The study involved two experiments, each following a group of 80 lambs through their first grazing season. Anthelmintic treatment of the whole group was determined by monitoring the weight gain of identified sentinel lambs within it every 2 weeks: when 40% of the sentinel lambs failed to reach their weight gain targets, the whole group was treated. The sentinel lambs consisted of 45% of the group (n = 36) in experiment one and 20% (n = 16) in experiment two. A control group of 20 lambs was co-grazed with the main group during both experiments; in experiment one, the sentinel approach was compared with a TST approach, in which control lambs were treated on an individual basis in response to weight gain. In experiment two, the sentinel approach was compared with conventional prophylaxis, where all lambs in the control group were treated at strategic time points throughout the season (= strategic prophylactic treatment). The sentinel lambs were found to be representative of overall group performance regardless of the proportion of sentinels within the group: they recorded similar growth rates and reached weight gain targets simultaneously at each time point and overall. Live-weight gain was also similar between sentinel and control animals in both experiments. The findings of the current study suggest that monitoring sentinel lambs comprising 20% of a group of grazing lambs is sufficient to determine the need for anthelmintic treatment within the whole group, and that this approach maintains production in line with conventional or TST treatment regimes.


Assuntos
Anti-Helmínticos , Nematoides , Infecções por Nematoides , Doenças dos Ovinos , Animais , Anti-Helmínticos/farmacologia , Anti-Helmínticos/uso terapêutico , Fezes , Infecções por Nematoides/veterinária , Contagem de Ovos de Parasitas/veterinária , Ovinos , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/prevenção & controle
15.
Phys Rev Lett ; 104(24): 241101, 2010 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-20867290

RESUMO

We have calculated the chameleon pressure between two parallel plates in the presence of an intervening medium that affects the mass of the chameleon field. As intuitively expected, the gas in the gap weakens the chameleon interaction mechanism with a screening effect that increases with the plate separation and with the density of the intervening medium. This phenomenon might open up new directions in the search of chameleon particles with future long-range Casimir force experiments.

16.
Equine Vet J ; 42(6): 494-9, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20716188

RESUMO

REASONS FOR PERFORMING STUDY: While previous studies have demonstrated an association between equine grass sickness (EGS) and the presence of Clostridium botulinum within ileal contents and faeces, no such associations with other intestinal-derived anaerobic bacteria have been extensively investigated. HYPOTHESIS: The prevalence of C. perfringens in the ileal contents and faeces of EGS horses is greater than control horses; the detection of C. perfringens in faeces by ELISA could be diagnostically beneficial in a clinical setting. METHODS: The prevalence of C. perfringens in faeces from EGS horses and healthy grazing control horses was determined by both selective culture and ELISA to permit both validation of the ELISA and inter-group comparisons. Additionally, the prevalence of C. perfringens (ELISA) in ileal contents from EGS horses was compared with that for control horses with nongastrointestinal disease. Finally, the prevalence of C. perfringens (ELISA) in faeces from EGS cases was compared with that from both horses with which they shared pasture at the time of disease onset and non-EGS colic horses. RESULTS: When compared with culture, the ELISA had a sensitivity and specificity of 86 and 98%, respectively. The prevalence of C. perfringens in faeces as determined by both culture and ELISA was significantly higher (P<0.001) for EGS horses (7/9 and 15/37, respectively) than for healthy grazing controls (0/60 and 1/74, respectively). The prevalence of C. perfringens in ileal contents from EGS horses (5/10) was greater than that for horses with nongastrointestinal disease (1/12) at a level that approached significance (P = 0.056). EGS cases had a significantly greater prevalence of C. perfringens in faeces (15/37) than co-grazing horses (1/18) and colic (1/16) horses. The specificity (93%) and PPV (94%) of the detection of C. perfringens by ELISA on faecal samples in relation to disease status (EGS compared with colic horses) was good. Sensitivity (41%) and NPV (39%) were poor. CONCLUSIONS AND POTENTIAL RELEVANCE: The use of a commercial ELISA to detect faecal C. perfringens may be diagnostically beneficial when differentiating EGS cases from colic cases, although further work is required to fully evaluate its potential.


Assuntos
Doenças do Sistema Nervoso Autônomo/veterinária , Infecções por Clostridium/veterinária , Clostridium perfringens/isolamento & purificação , Fezes/microbiologia , Conteúdo Gastrointestinal/microbiologia , Doenças dos Cavalos/microbiologia , Animais , Doenças do Sistema Nervoso Autônomo/epidemiologia , Doenças do Sistema Nervoso Autônomo/microbiologia , Estudos de Casos e Controles , Infecções por Clostridium/microbiologia , Ensaio de Imunoadsorção Enzimática/veterinária , Doenças dos Cavalos/epidemiologia , Cavalos , Íleo/microbiologia , Prevalência
17.
Equine Vet J ; 42(7): 652-7, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20840581

RESUMO

REASONS FOR PERFORMING STUDY: Cyathostomins are the principal pathogenic nematode of equidae worldwide. In other species mast cell (MC) proteinases, in particular chymases, appear to have protective roles. Knowledge of the equine intestinal immune response to cyathostomins is limited. OBJECTIVE: To investigate MC numbers and proteinase expression in equine cyathostomin-infected large intestine. HYPOTHESIS: MC populations in the large intestine are positively associated with cyathostomin burden and predominantly express chymase. METHODS: The caecal cyathostomin burden of naturally infected horses (n = 25) was determined by luminal counts and pepsin digest (mural count). MC were identified and enumerated in caecal tissue using toluidine blue (TB). Immunofluorescent labelling with polyclonal rabbit antibodies was used to demonstrate expression of equine tryptase and the chymase equine mast cell proteinase-1 (eqMCP-1) in Carnoy's fixed caecal sections. RESULTS: Significant positive linear relationships were found between TB-stained mucosal and submucosal MC counts and total cyathostomin burden (P<0.001, r² >36%), and both luminal (P<0.010, r² >25%) and mural (P<0.001, r² >36%) larval counts. Similar relationships were found with mucosal and submucosal chymase and tryptase-labelled MC counts (total: P<0.004, r² >29%; luminal: P<0.004, r² >30%; and mural: P<0.030, r² >19%). With all three MC labels, mean MC counts were higher in the submucosa compared to the mucosa (P<0.001). All caecal MC appeared to express chymase, with a small number of MC expressing both tryptase and chymase. CONCLUSIONS AND POTENTIAL RELEVANCE: Large intestinal MC counts are significantly associated with cyathostomin burden, with a predominance of chymase-positive MC. The burden is significantly associated with expression of MC proteinases, supporting their likely involvement in the intestinal immune response to cyathostomin infection. Further work to investigate the kinetics of proteinase expression, the possibility of differential proteinase expression and the role of these MC proteinases is warranted.


Assuntos
Ceco/citologia , Doenças dos Cavalos/parasitologia , Mastócitos/citologia , Infecções por Nematoides/veterinária , Peptídeo Hidrolases/metabolismo , Animais , Ceco/patologia , Feminino , Regulação Enzimológica da Expressão Gênica/fisiologia , Cavalos , Larva , Masculino , Infecções por Nematoides/patologia , Peptídeo Hidrolases/genética
18.
Int J Parasitol ; 50(2): 133-144, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31981671

RESUMO

Gastrointestinal nematodes are a significant threat to the economic and environmental sustainability of keeping livestock, as adequate control becomes increasingly difficult due to the development of anthelmintic resistance in some systems and climate-driven changes to infection dynamics. To mitigate any negative impacts of climate on gastrointestinal nematode epidemiology and slow anthelmintic resistance development, there is a need to develop effective, targeted control strategies that minimise the unnecessary use of anthelmintic drugs and incorporate alternative strategies such as vaccination and evasive grazing. However, the impacts climate and gastrointestinal nematode epidemiology may have on the optimal control strategy are generally not considered, due to lack of available evidence to drive recommendations. Parasite transmission models can support control strategy evaluation to target field trials, thus reducing the resources and lead-time required to develop evidence-based control recommendations incorporating climate stochasticity. Gastrointestinal nematode population dynamics arising from natural infections have been difficult to replicate and model applications have often focussed on the free-living stages. A flexible framework is presented for the parasitic phase of gastrointestinal nematodes, GLOWORM-PARA, which complements an existing model of the free-living stages, GLOWORM-FL. Longitudinal parasitological data for two species that are of major economic importance in cattle, Ostertagia ostertagi and Cooperia oncophora, were obtained from seven cattle farms in Belgium for model validation. The framework replicated the observed seasonal dynamics of infection in cattle on these farms and overall, there was no evidence of systematic under- or over-prediction of faecal egg counts. However, the model under-predicted the faecal egg counts observed on one farm with very young calves, highlighting potential areas of uncertainty that may need further investigation if the model is to be applied to young livestock. The model could be used to drive further research into alternative parasite control strategies such as vaccine development and novel treatment approaches, and to understand gastrointestinal nematode epidemiology under changing climate and host management.


Assuntos
Trato Gastrointestinal/parasitologia , Gado/parasitologia , Nematoides/isolamento & purificação , Infecções por Nematoides , Animais , Anti-Helmínticos/uso terapêutico , Bélgica/epidemiologia , Bovinos , Doenças dos Bovinos/parasitologia , Clima , Fezes/parasitologia , Ivermectina/uso terapêutico , Infecções por Nematoides/epidemiologia , Infecções por Nematoides/veterinária , Ostertagia/isolamento & purificação , Ostertagíase/epidemiologia , Ostertagíase/veterinária , Contagem de Ovos de Parasitas/veterinária , Dinâmica Populacional , Estações do Ano , Strongyloidea/isolamento & purificação , Trichostrongyloidea/isolamento & purificação
19.
Phys Rev Lett ; 103(22): 227401, 2009 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-20366125

RESUMO

Vibrational energy relaxation of the NH-, OH-, and OD-stretching modes in hydrogen-bonded liquids has been investigated by means of infrared pump-probe spectroscopy. The relaxation rates have been determined both in neat liquids and in isotopic mixtures with systematically varied isotope fractions. In all liquids, the vibrational relaxation rate increases as the isotope fraction is increased and reaches a maximum in the neat liquid. The dependence of the relaxation rate on the isotope fraction suggests a relaxation channel in which the vibrational energy is partitioned between accepting modes of two neighboring molecules.

20.
Science ; 294(5543): 813-7, 2001 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-11679661

RESUMO

Foot-and-mouth is one of the world's most economically important livestock diseases. We developed an individual farm-based stochastic model of the current UK epidemic. The fine grain of the epidemiological data reveals the infection dynamics at an unusually high spatiotemporal resolution. We show that the spatial distribution, size, and species composition of farms all influence the observed pattern and regional variability of outbreaks. The other key dynamical component is long-tailed stochastic dispersal of infection, combining frequent local movements with occasional long jumps. We assess the history and possible duration of the epidemic, the performance of control strategies, and general implications for disease dynamics in space and time.


Assuntos
Surtos de Doenças/veterinária , Febre Aftosa/epidemiologia , Modelos Estatísticos , Criação de Animais Domésticos , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/transmissão , Suscetibilidade a Doenças/veterinária , Febre Aftosa/prevenção & controle , Febre Aftosa/transmissão , Vírus da Febre Aftosa/imunologia , Modelos Biológicos , Ovinos , Doenças dos Ovinos/epidemiologia , Doenças dos Ovinos/transmissão , Conglomerados Espaço-Temporais , Processos Estocásticos , Reino Unido/epidemiologia , Vacinação/veterinária , Vacinas Virais/administração & dosagem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA