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1.
R Soc Open Sci ; 10(12): 231363, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38077216

RESUMEN

With advances in bio-logging technology, the posture of animals is now commonly described by inertial measurement units, which include tri-axial accelerometers to estimate pitch and roll angles. Many large seabirds use dynamic soaring flight to travel long distances, but this low-cost flight mode results in high centripetal acceleration, which obscures posture derived from accelerometers. Tri-axial magnetometers are not influenced by acceleration and might provide a way to estimate the posture of animals that experience high centripetal acceleration. We propose a new method to estimate the posture of dynamic soaring seabirds using tri-axial magnetometer data, with the assumption that they do not have large pitch angles during routine flight. This method was field-tested by deploying a combination of bio-logging devices on three albatross species breeding on Marion Island, using bird-borne video loggers to validate the roll angles. Validated data showed that the method worked well in most instances, but accuracy decreased when the heading was close to magnetic north or south. Accurate, fine-scale posture estimates may provide insight into dynamic soaring flight and allow estimates of fine-scale tracks using dead-reckoning, not only for seabirds, but potentially for other species where centripetal acceleration limits the use of accelerometers to estimate posture.

2.
Anim Biotelemetry ; 10(1): 10, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-37521810

RESUMEN

Background: Recent developments in both hardware and software of animal-borne data loggers now enable large amounts of data to be collected on both animal movement and behaviour. In particular, the combined use of tri-axial accelerometers, tri-axial magnetometers and GPS loggers enables animal tracks to be elucidated using a procedure of 'dead-reckoning'. Although this approach was first suggested 30 years ago by Wilson et al. (1991), surprisingly few measurements have been made in free-ranging terrestrial animals. The current study examines movements, interactions with habitat features, and home-ranges calculated from just GPS data and also from dead-reckoned data in a model terrestrial mammal, the European badger (Meles meles). Methods: Research was undertaken in farmland in Northern Ireland. Two badgers (one male, one female) were live-trapped and fitted with a GPS logger, a tri-axial accelerometer, and a tri-axial magnetometer. Thereafter, the badgers' movement paths over 2 weeks were elucidated using just GPS data and GPS-enabled dead-reckoned data, respectively. Results: Badgers travelled further using data from dead-reckoned calculations than using the data from only GPS data. Whilst once-hourly GPS data could only be represented by straight-line movements between sequential points, the sub-second resolution dead-reckoned tracks were more tortuous. Although there were no differences in Minimum Convex Polygon determinations between GPS- and dead-reckoned data, Kernel Utilisation Distribution determinations of home-range size were larger using the former method. This was because dead-reckoned data more accurately described the particular parts of landscape constituting most-visited core areas, effectively narrowing the calculation of habitat use. Finally, the dead-reckoned data showed badgers spent more time near to field margins and hedges than simple GPS data would suggest. Conclusion: Significant differences emerge when analyses of habitat use and movements are compared between calculations made using just GPS data or GPS-enabled dead-reckoned data. In particular, use of dead-reckoned data showed that animals moved 2.2 times farther, had better-defined use of the habitat (revealing clear core areas), and made more use of certain habitats (field margins, hedges). Use of dead-reckoning to provide detailed accounts of animal movement and highlight the minutiae of interactions with the environment should be considered an important technique in the ecologist's toolkit.

3.
Animal ; 15(6): 100234, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-34098494

RESUMEN

Urine patches deposited in pasture by grazing animals are sites of reactive nitrogen (N) loss to the environment due to high concentrations of N exceeding pasture uptake requirements. In order to upscale N losses from the urine patch, several urination parameters are required, including where, when and how often urination events occur as well as the volume and chemical composition. There are limited data available in this respect, especially for sheep. Here, we seek to address this knowledge gap by using non-invasive sensor-based technology (accelerometers) on ewes grazing in situ, using a Boolean algorithm to detect urination events in the accelerometer signal. We conducted an initial study with penned Welsh Mountain ewes (n = 5), with accelerometers attached to the hind, to derive urine flow rate and to determine whether urine volume could be estimated from ewe squat time. Then accelerometers attached to the hind of Welsh Mountain ewes (n = 30 at each site) were used to investigate the frequency of sheep urination events (n = 35 946) whilst grazing two extensively managed upland pastures (semi-improved and unimproved) across two seasons (spring and autumn) at each site (35-40 days each). Sheep urinated at a frequency of 10.2 ± 0.2 and 8.1 ± 0.3 times per day in the spring and autumn, respectively, while grazing the semi-improved pasture. Urination frequency was greater (19.0 ± 0.4 and 15.3 ± 0.3 times per day in the spring and autumn, respectively) in the unimproved pasture. Ewe squat duration could be reliably used to predict the volume of urine deposited per event and was thus used to estimate mean daily urine production volumes. Sheep urinated at a rate of 16.6 mL/s and, across the entire dataset, sheep squatted for an average of 9.62 ± 0.03 s per squatting event, producing an estimated average individual urine event volume of 159 ± 1 mL (n = 35 946 events), ranging between 17 and 745 mL (for squat durations of 1 to 45 s). The estimated mean daily urine volume was 2.15 ± 0.04 L (n = 2 669 days) across the entire dataset. The data will be useful for modelling studies estimating N losses (e.g. ammonia (NH3) volatilisation, nitrous oxide (N2O) emission via nitrification and denitrification and nitrate (NO3-) leaching) from urine patches.


Asunto(s)
Nitrógeno , Óxido Nitroso , Acelerometría/veterinaria , Amoníaco , Animales , Femenino , Estaciones del Año , Ovinos
4.
Proc Natl Acad Sci U S A ; 117(30): 17884-17890, 2020 07 28.
Artículo en Inglés | MEDLINE | ID: mdl-32661147

RESUMEN

Flight costs are predicted to vary with environmental conditions, and this should ultimately determine the movement capacity and distributions of large soaring birds. Despite this, little is known about how flight effort varies with environmental parameters. We deployed bio-logging devices on the world's heaviest soaring bird, the Andean condor (Vultur gryphus), to assess the extent to which these birds can operate without resorting to powered flight. Our records of individual wingbeats in >216 h of flight show that condors can sustain soaring across a wide range of wind and thermal conditions, flapping for only 1% of their flight time. This is among the very lowest estimated movement costs in vertebrates. One bird even flew for >5 h without flapping, covering ∼172 km. Overall, > 75% of flapping flight was associated with takeoffs. Movement between weak thermal updrafts at the start of the day also imposed a metabolic cost, with birds flapping toward the end of glides to reach ephemeral thermal updrafts. Nonetheless, the investment required was still remarkably low, and even in winter conditions with weak thermals, condors are only predicted to flap for ∼2 s per kilometer. Therefore, the overall flight effort in the largest soaring birds appears to be constrained by the requirements for takeoff.


Asunto(s)
Fenómenos Biomecánicos , Aves , Vuelo Animal , Animales , Ecología , Modelos Teóricos
5.
Ecol Appl ; 29(6): e01947, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31183944

RESUMEN

Telemetry is a key, widely used tool to understand marine megafauna distribution, habitat use, behavior, and physiology; however, a critical question remains: "How many animals should be tracked to acquire meaningful data sets?" This question has wide-ranging implications including considerations of statistical power, animal ethics, logistics, and cost. While power analyses can inform sample sizes needed for statistical significance, they require some initial data inputs that are often unavailable. To inform the planning of telemetry and biologging studies of marine megafauna where few or no data are available or where resources are limited, we reviewed the types of information that have been obtained in previously published studies using different sample sizes. We considered sample sizes from one to >100 individuals and synthesized empirical findings, detailing the information that can be gathered with increasing sample sizes. We complement this review with simulations, using real data, to show the impact of sample size when trying to address various research questions in movement ecology of marine megafauna. We also highlight the value of collaborative, synthetic studies to enhance sample sizes and broaden the range, scale, and scope of questions that can be answered.


Asunto(s)
Ecología , Ecosistema , Animales , Tamaño de la Muestra , Telemetría
6.
PLoS One ; 12(8): e0182333, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28796796

RESUMEN

Recent studies have suggested that changing direction is associated with significant additional energy expenditure. A failure to account for this additional energy expenditure of turning has significant implications in the design and interpretation of health interventions. The purpose of this study was therefore to investigate the influence of walking speed and angle, and their interaction, on energy expenditure in 20 healthy adults (7 female; 28±7 yrs). On two separate days, participants completed a turning protocol at one of 16 speed- (2.5, 3.5, 4.5, 5.5 km∙h-1) and angle (0, 45, 90, 180°) combinations, involving three minute bouts of walking, interspersed by three minutes seated rest. Each condition involved 5 m of straight walking before turning through the pre-determined angle with the speed dictated by a digital, auditory metronome. Tri-axial accelerometry and magnetometry were measured at 60 Hz, in addition to gas exchange on a breath-by-breath basis. Mixed models revealed a significant main effect for speed (F = 121.609, P < 0.001) and angle (F = 19.186, P < 0.001) on oxygen uptake ([Formula: see text]) and a significant interaction between these parameters (F = 4.433, P < 0.001). Specifically, as speed increased, [Formula: see text] increased but significant increases in [Formula: see text] relative to straight line walking were only observed for 90° and 180° turns at the two highest speeds (4.5 and 5.5 km∙hr-1). These findings therefore highlight the importance of accounting for the quantity and magnitude of turns completed when estimating energy expenditure and have significant implications within both sport and health contexts.


Asunto(s)
Metabolismo Energético , Velocidad al Caminar/fisiología , Adulto , Prueba de Esfuerzo , Femenino , Humanos , Masculino , Consumo de Oxígeno , Esfuerzo Físico , Adulto Joven
7.
J Fish Biol ; 88(1): 284-97, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26592370

RESUMEN

Metabolic rate is a critical factor in animal biology and ecology, providing an objective measure that can be used in attributing a cost to different activities and to assessing what animals do against some optimal behaviour. Ideally, metabolic rate would be estimated directly by measuring heat output but, until recently, this has not been easily tractable with fishes so instead metabolic rate is usually estimated using indirect methods. In the laboratory, oxygen consumption rate is the indirect method most frequently used for estimating metabolic rate, but technical requirements preclude the measurement of either heat output or oxygen consumption rate in free-ranging fishes. There are other field methods for estimating metabolic rate that can be used with mammals and birds but, again, these cannot be used with fishes. Here, the use of electronic devices that record body acceleration in three dimensions (accelerometry) is considered. Accelerometry is a comparatively new telemetric method for assessing energy metabolism in animals. Correlations between dynamic body acceleration (DBA) and oxygen consumption rate demonstrate that this will be a useful proxy for estimating activity-specific energy expenditure from fishes in mesocosm or field studies over extended periods where other methods (e.g. oxygen consumption rate) are not feasible. DBA therefore has potential as a valuable tool for attributing cost to different activities. This could help in gaining a full picture of how fishes make energy-based trade-offs between different levels of activity when faced with conflicting or competing demands arising from increased and combined environmental stressors.


Asunto(s)
Metabolismo Energético , Peces/metabolismo , Consumo de Oxígeno , Telemetría , Acelerometría , Animales , Natación
8.
Mov Ecol ; 3(1): 23, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26380711

RESUMEN

BACKGROUND: Research on wild animal ecology is increasingly employing GPS telemetry in order to determine animal movement. However, GPS systems record position intermittently, providing no information on latent position or track tortuosity. High frequency GPS have high power requirements, which necessitates large batteries (often effectively precluding their use on small animals) or reduced deployment duration. Dead-reckoning is an alternative approach which has the potential to 'fill in the gaps' between less resolute forms of telemetry without incurring the power costs. However, although this method has been used in aquatic environments, no explicit demonstration of terrestrial dead-reckoning has been presented. RESULTS: We perform a simple validation experiment to assess the rate of error accumulation in terrestrial dead-reckoning. In addition, examples of successful implementation of dead-reckoning are given using data from the domestic dog Canus lupus, horse Equus ferus, cow Bos taurus and wild badger Meles meles. CONCLUSIONS: This study documents how terrestrial dead-reckoning can be undertaken, describing derivation of heading from tri-axial accelerometer and tri-axial magnetometer data, correction for hard and soft iron distortions on the magnetometer output, and presenting a novel correction procedure to marry dead-reckoned paths to ground-truthed positions. This study is the first explicit demonstration of terrestrial dead-reckoning, which provides a workable method of deriving the paths of animals on a step-by-step scale. The wider implications of this method for the understanding of animal movement ecology are discussed.

9.
Conserv Biol ; 29(4): 1065-1075, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25833384

RESUMEN

Electronic tags (both biotelemetry and biologging platforms) have informed conservation and resource management policy and practice by providing vital information on the spatial ecology of animals and their environments. However, the extent of the contribution of biological sensors (within electronic tags) that measure an animal's state (e.g., heart rate, body temperature, and details of locomotion and energetics) is less clear. A literature review revealed that, despite a growing number of commercially available state sensor tags and enormous application potential for such devices in animal biology, there are relatively few examples of their application to conservation. Existing applications fell under 4 main themes: quantifying disturbance (e.g., ecotourism, vehicular and aircraft traffic), examining the effects of environmental change (e.g., climate change), understanding the consequences of habitat use and selection, and estimating energy expenditure. We also identified several other ways in which sensor tags could benefit conservation, such as determining the potential efficacy of management interventions. With increasing sensor diversity of commercially available platforms, less invasive attachment techniques, smaller device sizes, and more researchers embracing such technology, we suggest that biological sensor tags be considered a part of the necessary toolbox for conservation. This approach can measure (in real time) the state of free-ranging animals and thus provide managers with objective, timely, relevant, and accurate data to inform policy and decision making.


El Uso de Etiquetas de Sensor Biológico en la Conservación de Animales Resumen Las etiquetas electrónicas (plataformas tanto de bio-telemetría como de bio-registro) han informado a la conservación y a la política y práctica del manejo de recursos al proporcionar información vital sobre la ecología espacial de los animales y su ambiente. Sin embargo, la extensión de la contribución de los sensores biológicos (dentro de las etiquetas electrónicas) que miden el estado de un animal (p. ej.: ritmo cardíaco, temperatura corporal y detalles sobre el movimiento y la energética) es menos evidente. Una revisión de la literatura reveló que, a pesar de un número creciente de etiquetas sensoriales de estado disponibles comercialmente y un enorme potencial de aplicación de dichos dispositivos en la biología animal, hay pocos ejemplos de su aplicación en la conservación. Las aplicaciones existentes se rigieron por cuatro temas principales: cuantificar la perturbación (p. ej.: vehicular, de tráfico aéreo o de ecoturismo), examinar los efectos del cambio ambiental (p. ej.: cambio climático), entender las consecuencias de la selección y uso de hábitat, y estimar el gasto energético. También identificamos muchas otras maneras en que las etiquetas sensoriales podrían beneficiar a la conservación, como determinar la efectividad potencial de las intervenciones de manejo. Con el incremento en la diversidad de sensores en plataformas disponibles comercialmente, técnicas menos invasivas de etiquetado, tamaños más pequeños de los dispositivos, y más investigadores adoptando dicha tecnología, sugerimos que las etiquetas de sensor biológico se consideren como una parte de la caja de herramientas necesaria para la conservación. Esta estrategia puede medir (en tiempo real) el estado de animales libres y así proporcionar a los manejadores datos objetivos, oportunos, relevantes y precisos para informar la toma de decisiones y la política.


Asunto(s)
Conservación de los Recursos Naturales/métodos , Tecnología de Sensores Remotos/métodos , Migración Animal , Animales , Ecosistema , Movimiento
10.
J Sports Med Phys Fitness ; 55(10): 1049-57, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-24947810

RESUMEN

AIM: Accurate estimation of energy expenditure (EE) is important in human and animal behavior analysis. Rate of oxygen consumption (VO2) reflects EE during aerobic metabolism but is not always convenient. Alternative methods include heart rate (HR) and overall dynamic body acceleration (ODBA). A favorable ODBA-VO2 relationship was recently reported but the strength of association between VO2, ODBA, HR and its variability (HRV) is less clear. METHOD: Fifteen young (23±4 years) healthy males of similar aerobic fitness (maximal oxygen uptake, VO2max=49.7±8.5 mL·kg(-1)·min(-1)) carried out progressive maximal exercise. ODBA, HRV and V̇O2 were recorded continuously. Relationships between ODBA, HRV and V̇O2 were explored using regression methods. RESULTS: VO2 was strongly related to ODBA and RR during walking (R=0.45,0.30; P<5x10(-5)) and running (R=0.60,0.38; P<5x10(-5)). HRV was related to VO2 during walking only (R=0.11-0.26; 0.005

Asunto(s)
Metabolismo Energético/fisiología , Frecuencia Cardíaca/fisiología , Consumo de Oxígeno/fisiología , Oxígeno/metabolismo , Carrera/fisiología , Caminata/fisiología , Aceleración , Adulto , Animales , Humanos , Masculino , Monitoreo Fisiológico , Valor Predictivo de las Pruebas , Análisis de Regresión
11.
Ecol Lett ; 16(9): 1145-50, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23848530

RESUMEN

The tortuosity of the track taken by an animal searching for food profoundly affects search efficiency, which should be optimised to maximise net energy gain. Models examining this generally describe movement as a series of straight steps interspaced by turns, and implicitly assume no turn costs. We used both empirical- and modelling-based approaches to show that the energetic costs for turns in both terrestrial and aerial locomotion are substantial, which calls into question the value of conventional movement models such as correlated random walk or Lévy walk for assessing optimum path types. We show how, because straight-line travel is energetically most efficient, search strategies should favour constrained turn angles, with uninformed foragers continuing in straight lines unless the potential benefits of turning offset the cost.


Asunto(s)
Conducta Animal , Ecosistema , Conducta Alimentaria , Modelos Biológicos , Actividad Motora , Animales , Humanos
12.
Vet Pathol ; 49(3): 528-31, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22262350

RESUMEN

Seventy-four 9-week old female C57BL/6J mice housed in a conventional facility were manipulated to induce experimental autoimmune encephalomyelitis, among which 26 developed clinical signs including lethargy, absence of defecation, and abdominal distension. By gross necropsy examination, there was distension of the cecum and colon with fecal impaction. By histologic examination, there was severe ulcerative and proliferative typhlocolitis. Fecal ELISA confirmed the presence of toxins A and B of Clostridium difficile. Alteration in immune status of the immunocompetent mice, due to stress caused by experimental manipulation or autoimmune disease, may have led to intestinal dysbiosis, followed by opportunistic infections resulting in C. difficile-associated disease. This report brings to light the occurrence of the disease in immunocompetent laboratory mice during experimental manipulations associated with alteration in immune status, and it discusses potential hazards associated with conventional housing within a hospital-associated research institute.


Asunto(s)
Abdomen/patología , Clostridioides difficile/metabolismo , Colitis/veterinaria , Estreñimiento/veterinaria , Brotes de Enfermedades/veterinaria , Ratones Endogámicos C57BL , Enfermedades de los Roedores/microbiología , Enfermedades de los Roedores/patología , Animales , Proteínas Bacterianas/metabolismo , Toxinas Bacterianas/metabolismo , Colitis/microbiología , Colitis/patología , Estreñimiento/patología , Encefalomielitis Autoinmune Experimental/veterinaria , Enterotoxinas/metabolismo , Ensayo de Inmunoadsorción Enzimática/veterinaria , Femenino , Vivienda para Animales , Ratones
13.
Physiol Biochem Zool ; 84(2): 230-7, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-21460533

RESUMEN

Over the past few years, acceleration-data loggers have been used to provide calibrated proxies of energy expenditure: the accelerometry technique. Relationships between rate of oxygen consumption and a derivation of acceleration data termed "overall dynamic body acceleration" (ODBA) have now been generated for a range of species, including birds, mammals, and amphibians. In this study, we examine the utility of the accelerometry technique for estimating the energy expended by double-crested cormorants Phalacrocorax auritus to undertake a dive cycle (i.e., a dive and the subsequent pause at the surface before another dive). The results show that ODBA does not calibrate with energy expenditure in diving cormorants, where energy expenditure is calculated from measures of oxygen uptake during surface periods between dives. The possible explanations include reasons why energy expenditure may not relate to ODBA but also reasons why oxygen uptake between dives may not accurately represent energy expenditure during a dive cycle.


Asunto(s)
Aceleración , Aves/fisiología , Buceo/fisiología , Metabolismo Energético/fisiología , Monitoreo Fisiológico/instrumentación , Animales , Monitoreo Fisiológico/métodos , Esfuerzo Físico/fisiología , Reproducibilidad de los Resultados
14.
Vet Pathol ; 48(5): 933-41, 2011 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-21041540

RESUMEN

The goal of this study was to morphologically characterize a ligated ileal loop model of Salmonella enterica serotype Typhimurium infection in rhesus macaques (Macaca mulatta) and to verify the occurrence of Salmonella-induced cell death in vivo. Eight adult healthy male rhesus macaques were used for ligated ileal loop surgery. Four macaques had been intravenously inoculated with simian immunodeficiency virus (SIV) mac251. Ileal ligated loops were inoculated with wild-type (WT) S. Typhimurium strain IR715 (ATCC14028 nal (r)), an isogenic noninvasive mutant strain (ATCC14028 nal (r) ΔsipAΔsopABDE2), or sterile Luria Bertani broth. Loops were surgically removed at 2, 5, and 8 hours post-inoculation (hpi). Intestinal samples were processed for histopathology, immunohistochemistry for detecting Salmonella, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), and transmission electron microscopy. Combined histopathology scores were similar between SIV-infected and control macaques. As expected, the invasion-deficient mutant was less pathogenic than WT S. Typhimurium. Neutrophil infiltrate in the intestinal mucosa correlated with bacterial loads (r = 0.7148; P < .0001) and fluid accumulation (r = 0.6019; P < .0001) in the lumen of the intestinal loops. Immunolabeled WT S. Typhimurium was observed in the epithelium and lamina propria at the tip of the villi at 2 hpi, progressing toward deeper lamina propria at 5-8 hpi. Most TUNEL-positive cells localized to the lamina propria, and some had morphological features of macrophages. Ultrastructurally, bacteria were observed intracellularly in the lamina propria as well as within apoptotic bodies. This study provides morphological evidence of Salmonella-induced cell death in vivo in a relevant nonhuman primate model.


Asunto(s)
Enfermedades Intestinales/veterinaria , Macaca mulatta , Enfermedades de los Monos/microbiología , Salmonelosis Animal/patología , Salmonella typhimurium/aislamiento & purificación , Síndrome de Inmunodeficiencia Adquirida del Simio/patología , Virus de la Inmunodeficiencia de los Simios/aislamiento & purificación , Animales , Modelos Animales de Enfermedad , Inmunohistoquímica/veterinaria , Etiquetado Corte-Fin in Situ/veterinaria , Enfermedades Intestinales/inmunología , Enfermedades Intestinales/microbiología , Enfermedades Intestinales/virología , Mucosa Intestinal/microbiología , Mucosa Intestinal/ultraestructura , Mucosa Intestinal/virología , Masculino , Microscopía Electrónica de Transmisión/veterinaria , Enfermedades de los Monos/inmunología , Enfermedades de los Monos/patología , Enfermedades de los Monos/virología , Salmonelosis Animal/inmunología , Salmonelosis Animal/microbiología , Salmonelosis Animal/virología , Síndrome de Inmunodeficiencia Adquirida del Simio/inmunología , Síndrome de Inmunodeficiencia Adquirida del Simio/microbiología , Síndrome de Inmunodeficiencia Adquirida del Simio/virología , Estadísticas no Paramétricas
15.
J Exp Biol ; 212(Pt 4): 471-82, 2009 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-19181894

RESUMEN

Several methods have been used to estimate the energy expenditure of free-ranging animals. A relatively new technique uses measures of dynamic body acceleration as a calibrated proxy for energy expenditure and has proved an excellent predictor of energy expenditure in active animals. However, some animals can spend much of their time inactive and still expend energy at varying rates for a range of physiological processes. We tested the utility of dynamic body acceleration to estimate energy expenditure during a range of active (locomotion, eating) and inactive (digesting, thermoregulating) behaviours exhibited by domestic chickens. We also compared this technique with the more established heart-rate method for estimating energy expenditure. During activity, the error of estimation using body acceleration was very similar to that from the heart-rate method. Importantly, our results also showed that body acceleration can be used to estimate energy expenditure when birds are inactive. While the errors surrounding these estimates were greater than those during activity, and those made using the heart-rate method, they were less than those made using interspecific allometric equations. We highlight the importance of selecting a methodology that is appropriate for the life-history of the subject animal. We suggest that, to achieve the greatest possible accuracy and precision when estimating energy expenditure in free-ranging animals, the two techniques should be combined, and both heart rate (f(H)) and dynamic body acceleration could be included as covariates in predictive models. Alternatively, measures of acceleration can be used to ascertain which behaviour is being exhibited at each moment and hence which predictive model should be applied.


Asunto(s)
Pollos/fisiología , Metabolismo Energético , Frecuencia Cardíaca , Animales , Conducta Animal , Regulación de la Temperatura Corporal , Digestión , Ingestión de Alimentos , Actividad Motora , Consumo de Oxígeno
16.
Comp Biochem Physiol A Mol Integr Physiol ; 152(2): 197-202, 2009 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-18854225

RESUMEN

The ability to measure the energy expenditure of free-ranging animals is of great importance but the techniques available each have their limitations. Recently, as an alternative to more established techniques, an integrated measure of body acceleration termed overall dynamic body acceleration (ODBA) has been used as a calibrated proxy for rate of oxygen consumption (V(O(2))) and hence metabolic rate. The present study tested the potential of this technique, firstly by expanding the range of species for which the V(O(2))-ODBA relationship has been defined and secondly by undertaking a validation exercise to explore the accuracy of predictions made using ODBA. V(O(2))-ODBA relationships during terrestrial locomotion were established for several bipedal and quadrupedal endotherms and compiled with similar relationships previously determined in other species. A model incorporating all of these species showed that ODBA is an excellent predictor of V(O(2)) but there is variation in the V(O(2))-ODBA relationship between species, and further variation within some species. Including measurements such as body mass and structural size in prediction equations might further improve the predictive power of the 'ODBA technique' and eliminate species-specific differences. In the validation exercise, estimate errors were calculated for the species-specific predictive equations. The use of ODBA to estimate V(O(2)) was valid across all species examined and may show a greater potential for estimating energy expenditure for individual animals than other techniques.


Asunto(s)
Aceleración , Metabolismo Energético , Modelos Biológicos , Movimiento , Consumo de Oxígeno , Animales , Fenómenos Biomecánicos , Tamaño Corporal , Calibración , Prueba de Esfuerzo/normas , Humanos , Esfuerzo Físico , Reproducibilidad de los Resultados , Respiración , Pruebas de Función Respiratoria/normas , Especificidad de la Especie
17.
Physiol Biochem Zool ; 82(4): 396-404, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19018696

RESUMEN

Measurement of acceleration can be a proxy for energy expenditure during movement. The variable overall dynamic body acceleration (ODBA), used in recent studies, combines the dynamic elements of acceleration recorded in all three dimensions to measure acceleration and hence energy expenditure due to body movement. However, the simplicity of ODBA affords it limitations. Furthermore, while accelerometry data loggers enable measures to be stored, recording at high frequencies represents a limit to deployment periods as a result of logger memory and/or battery exhaustion. Using bantam chickens walking at different speeds in a respirometer while wearing an accelerometer logger, we investigated the best proxies for rate of oxygen consumption (Vo(2)) from a range of different models using acceleration. We also investigated the effects of sampling acceleration at different frequencies. The best predictor of Vo(2) was a multiple regression including individual measures of dynamic acceleration in each of the three dimensions. However, R(2) was relatively high for ODBA as well and also for certain measures of dynamic acceleration in single dimensions. The aforementioned are single variables, therefore easily derived onboard a data logger and from which a simple calibration equation can be derived. For calibrations of Vo(2) against ODBA, R(2) was consistent as sampling number decreased down to 600 samples of each acceleration channel per ODBA data point, beyond which R(2) tended to be considerably lower. In conclusion, data storage can be maximized when using acceleration as a proxy for Vo(2) by consideration of reductions in (1) number of axes measured and (2) sampling frequency.


Asunto(s)
Pollos/fisiología , Metabolismo Energético/fisiología , Consumo de Oxígeno/fisiología , Aceleración , Animales , Femenino , Distribución Aleatoria , Análisis de Regresión
18.
Ophthalmic Surg Lasers ; 32(2): 108-17, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11300631

RESUMEN

OBJECTIVE: To evaluate and compare the outcome of functioning filtration surgery followed by cataract surgery with posterior intraocular lens implantation by both phacoemulsification and extracapsular cataract extraction (ECCE) techniques in glaucomatous eyes. PATIENTS AND METHODS: We retrospectively evaluated the clinical course of 77 eyes (68 patients) that after successful trabeculectomy, underwent cataract surgery by either phacoemulsification or ECCE techniques. We determined the frequency of partial and absolute failure following cataract surgery by either phacoemulsification or ECCE in eyes with functioning trabeculectomies. Partial failure of intraocular pressure (IOP), control after cataract extraction was defined as the need for an increased number of antiglaucoma medications or argon laser trabeculoplasty to maintain IOP < or =21mm Hg. Complete failure of IOP control after cataract surgery was defined as an IOP >21 mm Hg on at least two consecutive measurements one or more weeks apart or the performance of additional filtration surgery. Failure rates were calculated using the Kaplan-Meier actuarial method. Failure rates between phacoemulsification and ECCE subgroups were compared using the log rank test. RESULTS: The probability of partial failure by the third postoperative year after cataract surgery was 39.5% in the phacoemulsification subgroup and 37.3% in the ECCE subgroup. This small difference is not statistically significant (P = 0.48). The probability of complete failure by the fourth postoperative year after cataract surgery was 12.0% in the phacoemulsification subgroup and 12.5% in the ECCE subgroup. This difference is also not statistically significant (P = 0.77). At the 6-month follow-up visit, visual acuity of both groups improved one or more lines in 87.0% of patients, and worsened one or more lines in 3.9% of patients. Sixty-one percent achieved visual acuity of 20/40 or better. The most frequent complication was posterior capsular opacification requiring laser capsulotomy that occurred in 31.2% of patients. CONCLUSION: Cataract extraction by either phacoemulsification or ECCE following trabeculectomy surgery may be associated with a partial loss of the previously functioning filter and the need for more antiglaucoma medications to control IOP.


Asunto(s)
Extracción de Catarata , Cirugía Filtrante , Anciano , Anciano de 80 o más Años , Catarata/etiología , Extracción de Catarata/efectos adversos , Extracción de Catarata/métodos , Femenino , Humanos , Presión Intraocular , Lentes Intraoculares , Masculino , Probabilidad , Reoperación , Estudios Retrospectivos , Insuficiencia del Tratamiento , Resultado del Tratamiento , Agudeza Visual
19.
Nature ; 406(6799): 955-6, 2000 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-10984040
20.
Cell Prolif ; 33(2): 63-73, 2000 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-10845251

RESUMEN

Opioid peptides serve as tonically active negative growth regulators in renewing and regenerating epithelia. To examine the involvement of opioids in renewal of the stratum corneum after tape stripping of tail skin, C57BL/6 J mice were given systemic injections of the potent opioid antagonist, naltrexone (NTX, 20 mg/kg i.p.) following injury. Blockade of opioid-receptor interaction by NTX for 4 h resulted in an elevation of 36-66% in basal cell DNA synthesis measured 24 h after injury. Injection of the endogenous opioid peptide, [Met5]-enkephalin (OGF, 10 mg/kg i.p.) 4 h before termination, suppressed radiolabelled thymidine incorporation in the basal cell layer by 37-46% at 24 h after wounding. The magnitude of the effects on DNA synthesis of OGF, but not NTX, depended on the timing of administration with respect to injury. OGF maximally depressed basal cell labelling (72%) when given 16 h after tape stripping. Concomitant administration of naloxone (10 mg/kg) with OGF blocked the inhibition of DNA synthesis; naloxone alone at the dosage utilized had no effect on cell labelling. Both OGF and its receptor, OGFr, were detected by immunocytochemistry in the basal and suprabasal cell layers, but not the cornified layer of tape stripped and uninjured tail skin. These results indicate: (a) a native opioid peptide and its receptor are expressed in epidermal cells of injured and uninjured mouse tail skin; (b) removal of the stratum corneum by tape stripping does not disrupt the function of the endogenous opioid growth system; (c) the proliferative response to wounding of the tail is tonically inhibited by the receptor-mediated action of an endogenous opioid peptide; and (d) DNA synthesis by basal cells can be elevated by disrupting opioid peptide receptor interactions.


Asunto(s)
ADN/biosíntesis , Encefalina Metionina/farmacología , Células Epidérmicas , Sustancias de Crecimiento/farmacología , Queratinocitos/efectos de los fármacos , Animales , División Celular/efectos de los fármacos , Epidermis/lesiones , Queratinocitos/química , Masculino , Ratones , Ratones Endogámicos C57BL , Microscopía Fluorescente , Naltrexona/farmacología , Antagonistas de Narcóticos/farmacología , Receptores Opioides/análisis , Organismos Libres de Patógenos Específicos , Cola (estructura animal) , Timidina/metabolismo , Timidina/farmacología , Tritio , Cicatrización de Heridas/efectos de los fármacos
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