Trade-offs between social behaviour and foraging by sheep in heterogeneous pastures.

In heterogeneous pastures, groups of sheep may have to alter their social behaviour in order to graze patches of preferred vegetation. In this event, patch size, inter-patch distance and the contrast between patch and background vegetation are likely to affect behaviour. In this experiment, groups of five female Scottish Blackface sheep grazed for 2-h periods in 0.1ha grass plots containing seven 1.5mx1.5m patches of improved vegetation, with inter-patch distances of 1.5, 6 or 11.5m. Background vegetation was of either medium or poor quality. Control plots contained no patches. On average, sheep spent 44% of the time grazing patches, although patches comprised only 1.6% of the total plot area. Inter-patch distance did not affect accumulated time spent grazing patches during the first 30min, but patch residence time and the number of sheep on a patch increased with inter-patch distance. The distribution of nearest neighbour distances was altered when patches were 6 or 11.5m apart, compared to no patches. Accumulated time spent grazing patches and the number of sheep on a patch were greater with poor than medium backgrounds. Sheep visited patches frequently and for short periods and it is suggested that sheep often moved off patches as a result of competition. The results provide evidence that sheep make trade-offs between social and foraging behaviour and demonstrate the importance of interactions between social spacing and the size and spacing of vegetation patches, when sheep forage in heterogeneous pastures.

Antipyretic effects of dipyrone versus ibuprofen versus acetaminophen in children: results of a multinational, randomized, modified double-blind study.

This study compared the antipyretic effectiveness of acetaminophen, ibuprofen, and dipyrone in young children with fever. The results were based on a modified double-blind, randomized, multinational trial that evaluated 628 febrile children, aged 6 months to 6 years. All three drugs lowered temperature in the 555 patients completing the study. Temperature normalization rates in the ibuprofen and dipyrone groups (78% and 82%, respectively) were significantly higher than the acetaminophen group (68%, P = 0.004). After 4 to 6 hours, mean temperature in the dipyrone group was significantly lower than the other groups, demonstrating longer temperature normalization with dipyrone. All three drugs showed comparable tolerability profiles.

Electron spin resonance assessment of susceptibility of roe deer (Capreolus capreolus) and red deer (Cervus elaphus) to oilseed rape (Brassica napus) poisoning.

Ex vivo studies have been carried out on roe and red deer erythrocytes using electron spin resonance spectroscopy. Free radical formation in cells challenged with the brassica-derived haemolysin, dimethyldisulphide, was measured using spin trapping techniques. Significantly greater amounts of radical were trapped in the roe deer cells which may relate to differences in the antioxidant profile of the two genotypes. Results suggest that roe deer have a greater risk of developing oilseed rape poisoning than red deer.

Effect of changing daylength on the diurnal pattern of intake and feeding behaviour in penned red deer (Cervus elaphus).

Voluntary food intakes by 12 housed red deer hinds were recorded during six 2-week periods between April and November. Diurnal patterns of intake and feeding activity were measured by weighing food at either 5-min (April, May and June) or 1-min intervals (July, September and November). At each time of the year, mean rates of food intake, amount of feeding activity and frequency of feeding bouts were significantly greater during periods of daylight than during darkness. Food intake rate and feeding activity during daylight did not vary significantly with length of day. In darkness, however, mean food intakes per hour were less and feeding activity per hour was greater in the months when day-length was short.

The role of free radicals in brassica-induced anaemia of sheep: an ESR spin trapping study.

The formation of reactive free radical species in sheep erythrocytes challenged with dimethyldisulphide, a brassica-derived haemolysin, has been investigated by electron spin resonance spectroscopy using the spin trap alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone. Erythrocytes exposed to this agent undergo a burst of free radical activity as demonstrated by the appearance of a spin adduct. The results suggest that haemolytic anaemia which can occur in sheep grazing forage brassicas is a consequence of oxidative stress.

Evaluación de un programa de pesquisa de hipoacusia en recien nacidos / Evaluation of the program of research on hypoacusia in newborn infants

Un equipo multidisciplinario desarrolló el Programa de Pesquisa de Niños Sordos (PROPENSO) en dos maternidades de la ciudad de Buenos Aires, una pública, R. Sardá (RS) y la otra privada del Sanatorio Otamendi y Miroli (SOM). El tamizado sistemático de 5489 recién nacidos desde mayo a diciembre de 1984 reveló 267 (4,8 por ciento) que reunían factores de "alto riesgo" para hipoacusia. La evaluación diagnóstica posterior, realizada en su mayoría en el centro del CEIDHI se completó en 155 (58 por ciento) niños de la cohorte de riesgo: 112 (52,6 por ciento) de los 213 pesquisados en RS y 43 (79,6 por ciento) de los 54 del SOM. En esta etapa se analizó la validez de una prueba subjetiva (audiometría conductual) en relación a un barrido de alta intensidad con potenciales evocados audiométricos de tronco (PEAT) observando una sensibilidad de 46 por ciento y una especificidad de 94 por ciento. Se detectaron finalmente 4 lactantes con hipoacusia severa bilateral persistente y 5 con sordera unilateral y se inició en ellos tempranamente la orientación y tratamiento. Debe contemplarse, para mejorar la eficiencia de futuras estrategias de pesquisa de hipoacusia infantil, que: a) el uso de un listado para identificar factores de riesgo en recién nacidos es un procedimiento efectivo, b) es difícil lograr el seguimiento ambulatorio, especialmente para familias de bajos ingresos, y c) la audiometría conductal parece ser un método suficientemente confiable para el reconocimiento inicial de hipoacusia severa (pero no en los primeros meses de vida).

Evaluación de un programa de pesquisa de hipoacusia en recien nacidos / Evaluation of the program of research on hypoacusia in newborn infants

Un equipo multidisciplinario desarrolló el Programa de Pesquisa de Niños Sordos (PROPENSO) en dos maternidades de la ciudad de Buenos Aires, una pública, R. Sardá (RS) y la otra privada del Sanatorio Otamendi y Miroli (SOM). El tamizado sistemático de 5489 recién nacidos desde mayo a diciembre de 1984 reveló 267 (4,8 por ciento) que reunían factores de "alto riesgo" para hipoacusia. La evaluación diagnóstica posterior, realizada en su mayoría en el centro del CEIDHI se completó en 155 (58 por ciento) niños de la cohorte de riesgo: 112 (52,6 por ciento) de los 213 pesquisados en RS y 43 (79,6 por ciento) de los 54 del SOM. En esta etapa se analizó la validez de una prueba subjetiva (audiometría conductual) en relación a un barrido de alta intensidad con potenciales evocados audiométricos de tronco (PEAT) observando una sensibilidad de 46 por ciento y una especificidad de 94 por ciento. Se detectaron finalmente 4 lactantes con hipoacusia severa bilateral persistente y 5 con sordera unilateral y se inició en ellos tempranamente la orientación y tratamiento. Debe contemplarse, para mejorar la eficiencia de futuras estrategias de pesquisa de hipoacusia infantil, que: a) el uso de un listado para identificar factores de riesgo en recién nacidos es un procedimiento efectivo, b) es difícil lograr el seguimiento ambulatorio, especialmente para familias de bajos ingresos, y c) la audiometría conductal parece ser un método suficientemente confiable para el reconocimiento inicial de hipoacusia severa (pero no en los primeros meses de vida). (AU)

Chronic treatment with long-acting bromocriptine does not affect duration of the breeding season, voluntary food intake, body weight, or wool growth in the Scottish blackface ewe.

The aim of this study was to determine whether suppression of the seasonal increase in prolactin concentrations by chronic treatment with the dopamine agonist bromocriptine would affect onset of anoestrus, voluntary food intake, body weight, and wool growth in a seasonal breed of sheep. Groups of eight Scottish Blackface ewes were injected i.m. each week with either the vehicle (Group A) or 2.0 mg (Group B), 6.0 mg (Group C), or 18.0 mg (Group D) of bromocriptine in a long-acting formulation, commencing on 18 January and terminating on 25 July (midwinter to midsummer in the northern hemisphere). Immediately before the bromocriptine injection, blood samples were taken for progesterone and prolactin determination. Voluntary food intakes were measured daily, and body weights were recorded every fortnight. Estimates of wool growth were made by weighing wool clipped from a measured area of skin once a month. Treatment had no effect on onset of anoestrus, voluntary food intake, body weight, or wool growth. Plasma prolactin concentrations increased significantly in all groups during the treatment period. From January to April, all doses of bromocriptine significantly reduced prolactin concentrations but later in the study (May and June) prolactin was significantly suppressed in Group D only, although even in this group prolactin concentrations increased between March and June. Pituitary prolactin content, measured at the end of the study in July, was also suppressed by bromocriptine. The gradual increase in prolactin concentrations in ewes receiving chronic bromocriptine was further investigated by treating a fifth group of ewes (Group E) with 18.0 mg of long-acting bromocriptine each week, commencing on 20 June.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of melatonin and a dopamine agonist and antagonist on seasonal changes in voluntary intake, reproductive activity and plasma concentrations of prolactin and tri-iodothyronine in red deer hinds.

Three experiments were conducted in the period between July and November with non-lactating red deer hinds to describe the effects of treatment with melatonin during this period on voluntary food intake (VFI), the onset of the breeding season, coat changes and plasma concentrations of prolactin and triiodothyronine (T3), and to examine whether prolactin mediated the observed effects. In experiment 1, eight animals were treated orally each day with either 10 mg melatonin at 16.00 h or 10 mg melatonin at 16.00 h plus 10 mg domperidone (a dopamine antagonist) given twice daily for 120 days from July; eight animals were maintained as controls. In experiment 2, the same numbers of animals per treatment were used to compare treatments in which 10 mg melatonin or 20 mg bromocriptine (a dopamine agonist) were given orally each day at 16.00 h for 119 days from late June and compared with an untreated control group. In experiment 3, six animals were treated daily for 105 days from mid August with 5 mg domperidone given i.m. and compared with six control animals. In experiments 1 and 2, the VFI of control animals reached a peak in late August and thereafter declined. Melatonin-treated animals showed a similar pattern but the peak in VFI was significantly (P less than 0.05) advanced by 2 weeks compared with controls, although the VFIs of both groups were similar in November.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian variation in abomasal digesta flow in grazing ewes during lactation.

1. Lactating grazing ewes, fistulated at the rumen and abomasum were either not supplemented or offered, individually, 600 g/d of either pelleted, molassed sugar-beet pulp ('energy' supplement) or a pelleted 1:1 (w/w) mixture of this feed and formaldehyde-treated soya-bean meal ('protein' supplement). Digesta flows at the abomasum were estimated from the concentrations of the markers CrEDTA and ruthenium phenanthroline complex, during their administration by continuous intra-rumen infusion. Digesta samples were taken at 09.00 hours and at six further times at 4 h intervals. This was repeated 2 d later. 2. No significant difference in flow between days was noted. Daily flows of dry matter (DM) and non-ammonia-nitrogen (NAN) (g/d) in supplemented ewes were significantly higher than in unsupplemented ewes, both in total digesta and its particulate phase. However, there were significant differences between sampling times or significant interactions between sampling time and supplement treatment. The results were therefore examined by Fourier analysis for possible circadian variation in digesta flow. As there was marked between-animal variability in flow-rate, the digesta-flow values for each sampling time were re-expressed as percentages of the flows calculated from daily mean marker concentrations. 3. In unsupplemented animals, marked and significant circadian variation was then identified in the flow of DM, total N and NAN in both whole digesta and the particulate phase. There was also significant circadian variation in the flow of DM, total N and NAN in the digesta of the supplemented ewes. Curves were of the same general shape as those for unsupplemented animals, but some significant differences were found, principally for digesta NAN flow. In both supplemented and unsupplemented animals, peak flows occurred in the period 20.00-01.00 hours. The proportion of DM and NAN flowing in the particulate phase was relatively constant through the day for unsupplemented ewes, but significant circadian variation occurred for supplemented ewes. 4. The possible mechanisms generating the circadian variation in digesta flow, such as grazing behaviour and the rumen digestion of supplements, are discussed. Values are also presented to indicate the extent of the likely errors if digesta flows were estimated from samples which did not represent all stages of the circadian pattern.

Simultaneous on-line measurement of blood K+, Ca2+, Na+, and pH with a four-function ChemFET integrated-circuit sensor.

On-line, simultaneous measurement of blood K+, Ca2+, Na+, and pH has been achieved by using a quadruple-function ChemFET (chemical-sensitive field-effect transistor) integrated-circuit sensor. Blood is withdrawn from the subject through an actively heparinized, dual-lumen cannula and passed into a flow-cell containing the sensor, in alternation with a calibration solution. A minicomputer controls the analysis system, logs data, and provides a continuous, graphic display of K+ and pH values.

Control of postoperative pain by interactive demand analgesia.

A demand analgesia apparatus is described. It communicates with the patient by means of spoken messages in any desired language, so that preliminary instruction is unnecessary. Dosage is limited by a reduction in respiratory rate, and by a series of electronic fail-safe circuits. Operation of the system is illustrated in a series of 10 patients given fentanyl "on demand" for the first 12 h after operation. The mean dose rate 0.73 +/- 0.49 microgram min-1. There was no evidence of cumulation or tolerance during the period of study.

Fazadinium and pancuronium: a pharmacodynamic study.

The neuromuscular blocking characteristics of fazadinium and pancuronium were compared using a general pharmacodynamic model. Since it characterizes the overall relationship between dose and effect, the model can be used to determine precisely equipotent doses, compare time-effect curves, and reconcile the apparently inconsistent clinical and pharmacokinetic characteristics of the two drugs. Fazadinium was shown to have a shorter duration than pancuronium, and appeared to exhibit less variation between subjects. The potency ratio varied between 3.4 : 1 and 7.2 : 1, depending upon the definition chosen. A general solution for the three-compartment open mammillary model, following any set of initial conditions if presented as an appendix. These equations allow explicit computation of any pattern of drug incrementation into any compartment of the model.

A pharmacodynamic model for pancuronium.

It has been demonstrated that a simple two-compartment kinetic model may account for the changes in plasma concentration of pancuronium after i.v. administration. However, it can be shown that this simple model does not account satisfactory for the observed changes in muscle twitch response. By the addition of a receptor (biophase) compartment, twitch response can be reconciled with model behavior and the characteristics resemble those predicted by animal studies. The complete model is applied to the problem of total renal failure, and shows that patients with this condition are likely to be marginally resistant to small doses of pancuronium, with a normal rate of recovery. However, larger doses are likely to result in delayed recovery, the duration of effect increasing in a dose-dependent manner.