A report of behavioral lateralization in an infant orang-utan (Pongo pygmaeus)

The limb used to perform seven common activities was recorded during weekly observations of an infant orang-utan. For five of these behaviors, preferences were found that remained consistent in their direction, although there were week to week fluctuations in magnitude. Most notably, a right hand preference was found for nonfood reaching and a right hindlimb preference appeared for initiating locomotion. Although initially, food reaching was predominantly with the right hand, a shift toward preferential left hand use occurred during the final weeks of the study. Additionally, a left hand preference appeared when the infant touched either its body or head.     

Role of angiotensin II in oral contraceptive hypertension in anesthetized rats

Rats fed a diet containing an oral contraceptive estrogen-progestogen mixture (Enovid) for 26 weeks developed a significant (P<0.01) elevation in mean arterial pressure (145 ± 6 mm Hg) when compared to a control group of rats fed the same diet without oral contraceptive steroids (mean arterial pressure averaged 117 ± 6 mm Hg). Infusion of [Sar¹, Ala⁸] angiotensin II, a competitive antagonist of angiotensin II, reduced the mean arterial pressure (P<0.01) in the oral contraceptive-treated rats to 117 ± 9 mm Hg, while infusion of this angiotensin II analogue into the control rats did not lower the arterial pressure. These studies provided evidence that angiotensin II may be involved in the hypertension produced by Enovid treatment in rats.     

Mechanoreception in marine copepods: electrophysiological studies on the first antennae

Neural activity was recorded extracellularly at the base ofthe first antenna in 15 marine copepods. Controlled mechanicalstimuli were delivered with a vibrator driven by a waveformgenerator. Many species exhibited responses characterized bya large number of small spikes, while others were characterizedby the presence of a small number of large units. Two bay species,Labidocera madurae and Acartia fossae, exhibited large unitsthat could be easily distinguished from the background activityof smaller units. In these species, the antennal receptors firedshort latency (>5 ms) trains of one to several impulses inresponse to a brief mechanical stimulus and sustained trainsto a prolonged sinusoidal stimulus. They were extremely sensitiveto small displacements and sensitivity increased with stimulusfrequency. The receptors responded to stimuli between 40 and1000 Hz and receptors required displacement velocities of 20µm s^–1 or more to fire. Displacements as small as10 nm were capable of triggering spikes. With an increase inthe amplitude of the displacement, a decrease in the latencyand an increase in the number of units recruited and/or firingfrequency was recorded. Phase-locking to oscillatory stimuliwas observed over a frequency range of 80–500 Hz. Neuralactivity increased in response to bending of individual setae.Setae appear innervated and structurally constrained to movementsin specific directions. These experiments suggest that (i) somecopepod setal receptors may be more nearly velocity detectorsthan purely displacement sensors, (ii) they may be capable ofsensing closely spaced stimuli, (iii) the patterns of responsemay code for intensity and duration of the stimulus, and (iv)receptors may be capable of supplying directional information.     

Peptic ulcer disease: a clinical study in 73 children

Seventy-three children with peptic ulcer have been admitted to The Montreal Children''s Hospital and l''Hôpital Sainte-Justine over the past 11 years. The primary ulcer group comprised 39 duodenal and nine gastric ulcers; repeat contrast studies were necessary to demonstrate a crater in 25%. Vomiting was especially prominent in the younger patients (1 month to 6 years). Pain was present in the majority of older patients (6 to 18 years) but was considered “typical” in no more than one third. Bleeding occurred more commonly in the older children but five had occult bleeding only. There was a positive family history in 11 children with primary duodenal ulcers but in none of those with gastric ulcers. Follow-up in 34 cases with primary ulcers showed that close to two thirds of the older children have had recurrent problems. Bleeding and/or perforation was the most common mode of presentation in 25 cases of secondary ulcers. Corticosteroids and increased intracranial pressure were the most frequently associated factors, the younger age group being at greater risk.     

Ecological correlates of lion social organization (Panthers, leo)

Data on lion home range size, pride size, density, group size, cub survival, litter size and adult sex ratio were extracted from studies carried out in 10 habitats. The data were compared with five measures of food supply: mean prey biomass, prey biomass during the season of greatest abundance, prey biomass during the season of least abundance, biomass of middle-sized prey species (i.e. those with mean adult live-weights between 50 and 250 kg), and the mean size of carcasses fed on by lions. The results indicated that range size is inversely correlated with the abundance of prey during the period of least abundance, but not with overall prey abundance. Range size showed no consistent variation with pride size or with minimum metabolic requirements. Pride size (measured in terms of average number of animals per pride and average number of adult females) and cub survival strongly correlated with lean season food abundance. No relationship was found between group size or litter size and any of the measures of food supply Adult sex ratio did not vary consistently with food supply or lion density, although the data did suggest that prides inhabiting small, circumscribed reserves may experience less inter-male competition and this, in turn, may affect the adult sex ratio.