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PubMed2005

Behavior, physiology, and performance of bulls mixed at the onset of finishing to form uniform body weight groups.

In some production settings, beef bulls are mixed at the beginning of the finishing period to obtain homogeneous groups to facilitate finishing and to produce more homogeneous carcasses. Given the stress induced by mixing, we questioned whether this practice was profitable. Sixty-four young bulls were finished in groups of four over 8 mo. They were either mixed or unmixed and had either homogeneous vs. heterogeneous BW at the beginning of finishing. Behavioral traits (social behavior following mixing and general activities during the finishing period), stress measurements (cortisol concentration, adrenal weight, catecholamine-synthesizing enzyme activity, and pain sensitivity), and production traits (growth rate, homogeneity, feed efficiency, and carcass measurements) were evaluated. Bulls reacted to the mixing with increased frequency of social interactions (agonistic interactions: 17.9 in mixed vs. 1.2 in unmixed bulls, P < 0.001; sexual interactions: 9.6 vs. 1.7, P < 0.001; nonagonistic interactions: 5.25 vs. 3.1, P < 0.05). Agonistic and sexual interactions were more frequent between bulls of homogeneous BW (P < 0.05). Throughout the finishing period, the synchronization of activity tended to be lower between mixed bulls (P = 0.09). At slaughter, the activity of tyrosine hydroxylase, a catecholamine-synthesizing enzyme, was increased in mixed bulls (1.52 vs. 1.16 nmol.h(-1).mg(-1), P < 0.05), which may indicate chronic stress. No differences were noted in ADG or carcass traits among treatments. The variability of BW within groups increased in groups that were initially homogeneous, whereas it decreased in groups that were initially heterogeneous. In conclusion, mixing young beef bulls at the beginning of the finishing period did not have detrimental effects on health and production, but mixing induced stress, perhaps due to decreased cohesion within groups. Thus, we failed to confirm the proposed benefit of mixing bulls to homogenize their BW at the onset of finishing because BW homogeneity within groups was not maintained throughout the finishing period.

Adrenal Glands↗

PubMed1999

Autoregressive modeling of the EEG in systemic kainic acid-induced epileptogenesis.

Background activity as well as three kinds of bilateral epileptiform discharges, recorded from the cerebral cortex and hippocampus of freely behaving rats treated with intravenous kainic acid (KA), were analysed by the directed transfer function (DTF) method within multivariate autoregressive modeling of the EEG. This method reveals statistical influence (flow of activity) between brain regions at different frequencies. There was no significant influence between rhythms in different brain regions in the background EEG. Early after KA administration, low frequency rhythms (< 10Hz) in the frontal cortex began to lead slow rhythms in other areas and high frequency rhythms (20-60 Hz), possibly gamma oscillations, intensified in the hippocampus. In spike-wave discharges, frontal cortex led both low and high frequency rhythms. Initially during generalised non-convulsive discharges, slow rhythms originated from frontal cortex and high frequency rhythms from hippocampus while later, slow rhythms as well, often arose from hippocampus. During the convulsive discharge, the flow of activity of dominant slow rhythms repeatedly changed between hippocampus and neocortex, with more frequent dominance of the hippocampus, while hippocampus continued to lead high frequency rhythms. We conclude that KA-induced epileptiform discharges are cortical and hippocampal events, specifically that the frontal cortex is early to express low frequency rhythms and the hippocampus, high frequency rhythms. More generally, the findings suggest that epileptiform discharges result from interacting rhythms of different frequencies that arise from different structures, and that gamma oscillations possibly contribute to widespread synchronisation during some forms of epileptogenesis.

Animals↗

PubMed2006

Feed stalls affect the social and feeding behavior of lactating dairy cows.

The first objective of this study was to study the effects of increased bunk space on the frequency of aggressive behavior at the feed bunk and on feed access. The second objective was to determine whether the addition of partitions (feed stalls) between adjacent cows would provide additional protection while feeding, particularly for subordinate cows. Twenty-four lactating Holstein cows were subjected to each of 3 treatments in 3 successive 10-d treatment periods using a 3 x 3 Latin square design. The treatments tested were: 1) 0.64 m of feed bunk space/cow, 2) 0.92 m of feed bunk space/cow, and 3) feed stalls (0.87 m of feed bunk space/cow with feed stall partitions separating adjacent cows). Time-lapse video was used to quantify the feeding and standing behavior, as well as the aggressive behavior (displacements) displayed by the cows at the feed bunk. To meet our first and second objectives, we compared data from the 0.64 m/cow treatment with that from the 0.92 m/cow treatment, and data from the 0.92 m/cow treatment with that from the feed-stall treatment, respectively. Total daily feeding time increased when feed bunk space was increased from 0.64 to 0.92 m/cow. Further, the time spent standing in the feeding area while not feeding and the frequency of aggressive interactions at the feed bunk decreased when more bunk space was provided. The addition of feed stalls resulted in more pronounced effects compared with when cows had 0.92 m/cow of bunk space. The feed stalls also forced cows to change the strategy by which they displaced others from the feed bunk, forcing them to also initiate contact at the rear of the animal they were displacing rather than only from the front and side, as in the other 2 treatments. Further, when the cows were provided with additional feeding space, particularly when combined with feed stalls, those cows with lower social status at the feed bunk experienced the greatest decreases in the number of times they were displaced per day. The results indicated that providing increased feed bunk space, particularly when combined with feed stalls, will improve access to the feed and reduce competition at the feed bunk, particularly for subordinate cows.

Aggression↗

PubMed1984

Pulsed electromagnetic fields increase the rate of rat liver regeneration after partial hepatectomy.

Pulsed extremely low-frequency electromagnetic fields interact with rat liver regeneration following partial hepatectomy when delivered to the rats immediately after the operation and every 12 hr thereafter. This interaction results first in an increased ornithine decarboxylase activity, an enzyme used as an early marker of cell growth. The rate of labeled thymidine incorporation into DNA is also increased by the treatments with magnetic fields during the early phases of liver regeneration. Glycogen depletion and lipid accumulation, two well-known early peculiar phenomena of liver regeneration following partial hepatectomy, are quantitatively decreased by the treatments with electromagnetic fields. The recovery to normal glycogen and lipid contents is completed within 5 days after surgery, instead of 7 days as found in control rats.

Animals↗

PubMed1991

Live performance and yields of broilers provided various lighting schedules.

The purpose of the present study was to measure performance and carcass yield from broilers maintained on photoschedules that may influence incidence of leg disorders. Day-old male broilers were placed on litter floors of light-controlled chambers. Four chambers were randomly assigned to each of four light treatments: 1) 23 h light (L): 1 h dark (D) from 1 to 56 days of age (designated extended, E); 2) 1L:3D from 1 to 56 days (intermittent, I); 3) 6L:18D from 1 to 14 days and 1L:3D from 15 to 56 days (brief-I, BI); and 4) 6L:18D from 1 to 14 days and 23L:1D from 15 to 56 days (brief-E, BE). Mean (+/- SEM) light intensity was 5.4 +/- .26 lx for all light treatments. At 13, 21, and 42 days of age, Treatments BI and BE had lower BW than Treatment E. The percentage of birds with leg abnormalities among treatments was greater at 56 days than at 42 days. The BI birds had significantly fewer leg abnormalities than E birds. There was an age by treatment interaction for the frequency of tibial dyschondroplasia (TD), with BI showing better recovery from TD at 56 days than other treatments. At 42 days of age, split breast yield (percentage of BW) was greater in E than I, and breast yield (percentage of lean carcass) was greater in E and BI compared with I. At 56 days of age, yield (percentage of BW) of tenders was lower in I and BI compared with E and BE.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2002

Evidence for two pitch encoding mechanisms using a selective auditory training paradigm.

The neural mechanisms underlying the perception of pitch, a sensory attribute of paramount importance in hearing, have been a matter of debate for over a century. A question currently at the heart of the debate is whether the pitch of all harmonic complex tones can be determined by the auditory system's using a single mechanism, or whether two different neural mechanisms are involved, depending on the stimulus conditions. When the harmonics are widely spaced, as is the case at high fundamental frequencies (FOs), and/or when the frequencies of the harmonics are low, the frequency components of the sound fall in different peripheral auditory channels and are then "resolved" by the peripheral auditory system. In contrast, at low F0s, or when the harmonics are high in frequency, several harmonics interact within the passbands of the same auditory filters, being thus "unresolved" by the peripheral auditory system. The idea that more than one mechanism mediates the encoding of pitch depending on the resolvability status of the harmonics was investigated here by testing for transfer of learning in F0 discrimination between different stimulus conditions involving either resolved or unresolved harmonics after specific training in one of these conditions. The results, which show some resolvability-specificity of F0-discrimination learning, support the hypothesis that two different underlying mechanisms mediate the encoding of the F0 of resolved and unresolved harmonics.

Adult↗

PubMed1999

MESA: a new configuration for measuring electromagnetic field fluctuations.

This paper describes how the multi-energy sensor array has been refitted to meet the needs of measuring geomagnetic and other types of electromagnetic phenomena in an environment. This portable laptop computer system was designed to measure the interaction of multiple frequencies with the psychological and physiological processes that underlie human exposure to electromagnetic fields across the spectra. New sensors and analytical software have been implemented in the new configuration.

Computer Systems↗

PubMed2006

Examining the nurse practitioner role in long-term care: evaluation of a pilot project in Canada.

This study examined the nurse practitioner (NP) role in three long-term care facilities in Ontario, Canada, to identify factors that facilitate or impede the implementation of this role. Facility staff were surveyed about their perceptions of the NP role, and the NP assigned to the facilities was interviewed. Findings indicated the NP had a positive impact on practice activities and staff assessment skills. Ratings of effectiveness and satisfaction with the role were high, although they varied by facility and the frequency of staff interaction with the NP. This study indicated NPs can significantly impact the primary care of residents in long-term care facilities. The NP role can be facilitated by clear delineation of the scope of practice, optimal NP to resident ratios, and organizational support.

Attitude of Health Personnel↗

PubMed2006

Temporal and dose-dependent relationships between in vivo B cell receptor-targeted proliferation and deletion-induced by a microbial B cell toxin.

The effective functioning of the adaptive immune system requires careful clonal regulation within the B cell compartment. Some microbial pathogens produce virulence factors, like staphylococcal protein A, which interact at high frequencies with B lymphocyte through unconventional binding sites in BCR variable region frameworks conserved during evolution. We have characterized the in vivo effect of staphylococcal protein A treatment on peripheral B cells bearing susceptible BCR, and found a dose-dependent direct relationship over the range of 2 mg to <0.2 microg in the magnitude of induced BCR-targeted supraclonal cell death. Significantly, some level of targeted B cell proliferation was always detectable, with greatest interim supraclonal expansion demonstrated at 2 days after 20-microg treatment. Subsequently, this transient expansion always collapsed. In direct comparisons, i.p. treatment was more efficacious than i.v. treatment, although at higher doses this finding was less marked. These studies elucidate a general paradigm in which in vivo encounters with a B cell superantigen are uniformly associated with proliferative expansion followed by deletion that is more rapid and complete with higher doses, whereas lower doses lead to greater transient in vivo expansion with delayed deletion to levels at later times that are still quantitatively proportional to the dose. Our results document the potent in vivo B cell-targeted properties of a microbial B cell superantigen, even at submicrogram doses associated with great molar excess of circulating Ig, and clearly illustrate the intertwined relationships between targeted proliferative cycling and apoptotic death that is induced by a microbial B cell superantigen.

Animals↗

PubMed1992

Falls among elderly people living at home: medical and social factors in a national sample.

Falls are the most common accidents among the elderly, and while medical risk factors are well known, less is known about the association of falls with social factors. The aims of this study were to estimate the incidence rate of falls in a national, representative sample of Israeli elderly and to examine the association of falls with selected medical and social factors. A special national survey conducted in 1985 by the Israel Central Bureau of Statistics showed that among a representative sample of 3,494 community-dwelling elderly persons aged greater than or equal to 65, 24% reported a fall in the past year; the rate was 16% among men and 31% among women. The majority of falls reported happened out of doors. Of those who fell 37% subsequently visited the emergency room. Analyses adjusted for age and sex showed that single persons, particularly women, living alone reported falls at a higher rate than their married counterparts. Analyses adjusted for age, sex and mobility level showed that frequency of social interaction was inversely related to reported falls. Use of sleeping pills, problems with vision, and mobility restrictions were associated with falls in age- and sex-adjusted analyses. Advanced age (greater than 75 years) was associated with repeated falls that occurred both in the home and outdoors.

Accidental Falls↗

PubMedDate not supplied

[The dynamics of intracortical interaction during thinking activities].

A new method is described of the brain mapping, based on determination of the probability of appearance of isofrequency components in the EEG derivations allowing to evaluate functional interaction of the brain structures in the process of psychic activity. The process of mental construction of visual image from separate elements includes three stages. At the stage of image search the focus of activity is in the occipital cortical area; in the stage of construction it moves to the frontal cortical areas; completion of the task and verbalization of the image are accompanied by joining of the cortical connections in common system. Alongside with the main focus of activity secondary focuses in the temporal cortex are also revealed during the search of the visual image. The topography of interaction at the frequencies of alpha-range in mainly determined by the stage of image construction. In case of prevalence of the image and abstract thinking shift is marked of the activity focuses at the frequencies of theta-range respectively to the right and left hemispheres.

Adolescent↗

PubMed1977

Factors influencing aggressive behavior and risk of trauma in the pigtail macaque (Macaca nemestrina).

Several experiments and surveys were conducted in a large colony of pigtail macaques (Macaca nemestrina) to determine some of the influences of spatial and social factors on aggressive behavior and risk of trauma. Female subjects exhibited more aggression when they had access to two-room suites than when they had access to single rooms. The frequency of aggressive interactions among females was positively related to the number of females per group. The presence of one or more males in groups inhibited aggressive interaction among females. Less aggression occurred among females in groups containing infants than in groups containing no infants. Provision of cover by introduction of concrete cylinders into rooms reduced aggression among members of stable groups. Subjects in newly-formed groups composed of unfamiliar animals sustained fewer injuries than did those in groups formed by merger of groups or subgroups of familiar animals.

Aggression↗

PubMed1983

Anchorage and lymphocyte function. Spreading-capacity distinguishes common thymocytes and peripheral T lymphocytes.

Contact of T-enriched human blood lymphocytes with an adhesive surface in the presence of Concanavalin A (Con A) almost immediately induced a sequence of motile changes in virtually all cells. The initial event in this spreading process was the formation of filopodia distinct from the microvilli of lymphocytes in suspension. The filopodia were accompanied by lamellipodia, ruffles and flattening of the nucleus. Contact with a nonadhesive substratum in the presence of Con A did not trigger this sequence of changes. Cytochalasin B and D or low temperature inhibited the contact-induced changes. With the exception of a small number of cells (5-15%), T-enriched lymphocytes that were allowed to settle in the absence of Con A showed a radius of action (area occupied by the cells/translational movement per hr) of 39 micrometers 2/ less than 1 micrometer. The small 'motile' population showed a radius of action of 74 micrometers 2/8 micrometers. The Con-A-mediated spreading-process yielded a radius of action of the lymphocytes of 117 micrometers 2/6 micrometers. This augmented radius of action markedly facilitated cell-cell interaction in a high frequency of the cells and appeared to be a prerequisite for such interactions at 'low' cell density. Thymocytes reactive with OKT 6 antibodies or belonging to the 'high-density' fraction of cells attached to a Con-A-coated surface to the same extent as peripheral OKT 3 positive lymphocytes, but did not exhibit the morphological changes characteristic of a spreading-process. In contrast, OKT 6 negative thymocytes or thymocytes with a relatively low density showed spreading indistinguishable from that of OKT 3 positive peripheral lymphocytes. These results characterize the spreading-process in human T lymphocytes and demonstrate its functional importance for interactions with the environment. Spreading-capacity appears to reflect the stage of maturation of T cells.

Animals↗

PubMed1983

The parcellation of the medial geniculate body of the cat defined by the auditory response properties of single units.

Single unit responses were recorded in the medial geniculate body (MGB) of anesthetized cats. In response to acoustical stimulation the properties of response latency, discharge pattern, frequency tuning, binaural interaction, and habituation were examined to allow an appraisal of the differentiation of the MGB by electrophysiological means. It is found that definite boundaries can be determined at which there is a distinct change in response properties; the position of these "physiological boundaries" seems to correspond with the boundaries between the seven subnuclei of the MGB described by Morest (Morest, D. K. (1964) J. Anat. 98: 611-630) in Golgi-stained material. Using these physiological boundaries to determine unit locations, population comparisons are made allowing the description of each subnucleus in terms of its auditory response properties. It is suggested that these properties, together with the limited information gained from Nissl cytoarchitecture, are sufficient to describe the location of physiological recording sites in the MGB.

Acoustic Stimulation↗

PubMed1993

Sound localization with hearing protectors.

A preliminary investigation was conducted of the ability of normal-hearing subjects to localize sound while wearing hearing protective devices. Performance with Bilsom 2392 level-dependent stereophonic muffs with limited amplification was compared with that of conventional level-independent E-A-R 3000 muffs and E-A-R plugs. Sound localization was assessed using an array of six speakers, positioned in the horizontal plane, 1 m from the subject at azimuth angles of 30 degrees, 90 degrees, 150 degrees, 210 degrees, 270 degrees and 330 degrees. The stimulus was an 80 dB SPL 300-ms one-third octave noise band centered at 500 Hz or 4000 Hz. The experiment was conducted in quiet and in a 65 dB SPL white noise background. The results indicated that at 500 Hz, the wearing of protectors resulted in a 20% decrease in the accuracy of speaker identification but the three types of device were indistinguishable. At 4000 Hz, performance was best in the unoccluded condition and relatively worst with the level-dependent muff. Error patterns depended on the interaction of stimulus frequency, speaker azimuth and protector. Front/back errors in localizing the high-frequency stimulus were greatest with the conventional muff, whereas right/left errors were greatest with the level-dependent muff. Protected listening was generally unaffected by the presence of a noise background for both of the frequencies tested.

Adult↗

PubMed1996

[Laser Doppler flowmetry--a new promising technique for assessment of the microcirculation].

The laser Doppler flowmetry is a new technique for evaluating microcirculation. It is based on the Doppler phenomenon-reflected light changes its frequency when it interacts with moving objects such as red blood cells. The source of light is 2 mW He-Ne laser. The light penetrates into the tissue to the depth of 1 mm, and measures microvascular blood flow throughout it. This technique is objective, harmless even during prolonged exposition, repeatable, and very sensitive even to small changes in the blood flow. Because of difficulties with determination of the perfusion normal values and several factors disturbing microcirculation, the most objective results are obtained with dynamic tests. They measure a response of microcirculation to local ischemia, cooling or given medicines. A disadvantage is its high sensitivity to motion-produced disturbances. Laser Doppler flowmetry may be used not only in scientific investigations. It is of diagnostic value in plastic surgery, vascular surgery, dermatology, internal medicine, dentistry, and neurology.

Equipment Design↗

PubMed1997

Comparison of cardiac and 60 Hz magnetically induced electric fields measured in anesthetized rats.

Extremely low frequency magnetic fields interact with an animal by inducing internal electric fields, which are in addition to the normal endogenous fields present in living animals. Male rats weighing about 560 g each were anesthetized with ketamine and xylazine. Small incisions were made in the ventral body wall at the chest and upper abdomen to position a miniature probe for measuring internal electric fields. The calibration constant for the probe size was 5.7 mm, with a flat response from at least 12 Hz to 20 kHz. A cardiac signal, similar to the normal electrocardiogram with a heart rate of about 250 bpm, was readily obtained at the chest. Upon analysis of its spectrum, the cardiac field detected by the probe had a broad maximum at 32-95 Hz. When the rats were exposed to a 1 mT, 60 Hz magnetic field, a spike appeared in the spectrum at 60 Hz. The peak-to-peak magnitudes of electric fields associated with normal heart function were comparable to fields induced by a 1 mT magnetic field at 60 Hz for those positions measured on the body surface (where induced fields were maximal). Within the body, or in different directions relative to the applied field, the induced fields were reduced (reaching zero at the center of the animal). The cardiac field increased near the heart, becoming much larger than the induced field. Thus, the cardiac electric field, together with the other endogenous fields, combine with induced electric fields and help to provide reference levels for the induced-field dosimetry of ELF magnetic field exposures of living animals.

Anesthesia↗

PubMed1997

Improvement of hemispatial neglect with cold-water calorics: an electrophysiological test of the arousal hypothesis of neglect.

Introducing ice-water into the left ear of right-brain-damaged patients attenuates unilateral neglect symptoms. By examining EEG changes over each hemisphere during this procedure, we were able to test a hypothesis concerning the mechanism of cold-water calorics and the attention-arousal hypothesis of hemispatial neglect. We present a case study of an 83-year-old woman with a massive right-hemisphere CVA exhibiting severe hemispatial neglect. Caloric stimulation produced a leftward eye deviation to central position, and a temporary partial remission of neglect symptoms. Significant changes in EEG activation indicated a central mechanism associated with the regularization of eye gaze. Caloric stimulation also produced a significant interaction between EEG frequency band and hemisphere, indicating that while both hemispheres increased in cortical activation, the right hemisphere increase was significantly greater. This supports the activation-arousal hypothesis of neglect over the mutual inhibition model.

Aged↗