Age differences in arousal and vigilance in California ground squirrels (Spermophilus beecheyi).

Newly emerged pup, juvenile, and adult California ground squirrels (Spermophilus beecheyi douglasii) were videorecorded at a seminatural field site in northern California. Video data revealed age differences in the budgeting of ground squirrel behavior, habitat use, and physiological arousal as indicated by morphometric analyses of tail piloerection. Adults and juveniles devoted their time to foraging in the open at feeding stations while displaying low to moderate levels of arousal, respectively. Pups remained vigilant on the fringe of covered habitats while displaying comparatively higher levels of arousal. Higher pup arousal may facilitate memory formation during early stages of development.

Age differences in the response of California ground Squirrels (Spermophilus beecheyi) to avian and mammalian predators.

The antipredator behavior of juvenile and adult California ground squirrels (Spermophilus beecheyi) was videotaped in Experiment 1 to measure the effects of age on assessment of a briefly presented live dog and a model red-tailed hawk (Buteo jamaicensis) in simulated flight. Adult squirrels treated the hawk as more dangerous than the dog, whereas juvenile squirrels showed less differentiation of the predator types. Juvenile squirrels also perceived the dog as a more immediate danger than adult squirrels did. For Experiment 2, the red-tailed hawk model was compared with models of a nonthreatening turkey vulture (Cathartes aura) and crow (Corvus brachyrhynchos). Neither age class differentiated the avian models; however, the adult squirrels treated these birds as more threatening than the juvenile squirrels did. Both studies suggest that learning may contribute to predator assessment.

Effects of a single dose of the acetylcholinesterase inhibitor velnacrine on recognition memory and regional cerebral blood flow in Alzheimer's disease.

The effects of a single oral dose of the acetylcholinesterase inhibitor velnacrine maleate on word and object recognition memory and regional uptake of 99mTc-exametazime were examined in patients with Alzheimer's disease. Word recognition memory was marginally improved 2 h after 75 mg velnacrine. With the same dose of velnacrine a relative increase in superior frontal uptake of 99mTc-exametazime was shown with single photon emission computed tomography (SPECT). This suggests increased regional perfusion and metabolism as a consequence of cholinergic stimulation. The effect did not co-vary with the degree of memory improvement, but, instead, more cognitively impaired patients showed a greater increase in tracer uptake after velnacrine, suggesting cholinergic hypersensitivity in the brains of Alzheimer patients.

Clinical assessment of disease activity in rheumatoid arthritis.

A new experimental design was developed to study the value of clinical parameters of disease activity in patients with rheumatoid arthritis. Ten patients with classical rheumatoid arthritis were examined by five senior doctors in a department of medical rheumatology. In spite of an attempt to make the clinical examination as uniform as possible the inter-observer variation among the doctors was greater than the variation among the patients, for the following parameters: joint pain at rest, joint tenderness and joint swelling. An acceptable inter-observer variation in relation to patient variation was found for 1) a combined registration of joint pain at rest or on movement, 2) duration of morning stiffness, 3) grip strength, 4) subjective well-being as indicated on a visual analogue scale, 5) fingertip--palm distance, and 6) maximum flexion-extension in elbows, wrists and knees. The variation from morning to afternoon and from day to day was negligible. It is concluded that registration of elaborated articular scores is useless in the daily routine in rheumatological departments when different doctors examine the patients.