Influence of environment on passive immunity in calves

Passive immunity in neonatal calves is influenced by environment. Placing newly born Holstein calves (108 head) in three different housing environments (shade, cooled shade, hutch) during hot weather produced differences in body temperature, serum cortocosteroids, immunoglobulin IgG1 concentrations, and mortality. Experimental design permitted examination of effects due to treatments, time, differences in colostrum, and climatic environment in an analysis of variance. Calves exposed to the hotter, less desirable environment responded by having a higher mortality, higher serum corticosteroid concentration, and lower serum immunoglobulin IgG1 at 2 and 10 days after birth. All of these were correlated. Calves that died had serum immunoglobulin IgG1 falling below the mean for all experimental calves.     

Structural units and the redintegrative power of picture fragments

We suppose that line drawings are perceived and represented in memory as a hierarchy of related parts and subparts, as dictated by Gestalt laws like common direction and spatial proximity. Therefore, a figure fragment comprising a natural part of an orginally studied pattern should serve as a strong retrieval cue for redintegrating memory for the pattern, whereas an equally large fragment suggesting either no units of misleading units should lead to poorer recall. This was confirmed in an experiment in which subjects studied 33 nonsense line drawings; recall of each was tested with good, mediocre, or bad (misleading) fragments of the original patterns. Good cues had about five time more redintegrative power than bad cues. A second experiment testing multiple-choice recognition memory showed that subjects confused an originally studied pattern about four times as often with a structurally similar distractor as with a structurally dissimilar distractor (which had an equal-sized change). Thus, memory cuing by fragments and memory confusions with slightly altered distractors indicate the significant constitutents of a figure.     

A delayed suppression of the renin-aldosterone axis following saline infusion in human hypertension

The purpose of this study was to compare the acute suppressibility of the renin-angiotensin-aldosterone (RAA) axis in normotensive (n = 23) and essential hypertensive (n = 62) subjects. Only those hypertensive subjects with normal plasma renin activity (PRA) levels (sodium restricted, upright) were included in the study. Acute suppression of the RAA axis was determined by measuring PRA, plasma angiotensin II (A II), and plasma aldosterone (PA) at frequent intervals during the infusion of isotonic saline (500 ml/hour for 6 hours). Although all parameters fell significantly from control levels by 20-30 minutes in the normotensive subjects, we found that 60% of the hypertensive subjects showed no significant decline in PRA or PA until 120-240 minutes after beginning the infusion. The other hypertensive subjects showed normal RAA suppression. In addition, while there were no significant differences between the three groups in control PRA or PA levels, we found that the PA levels from 30 to 240 minutes during the saline were significantly higher (P less than 0.01) in the hypertensive subjects with delayed suppression. That there were two distinct populations in the hypertensive group was suggested by the bimodality of the frequency response curve, with peaks occurring at 30 and 240 minutes. These studies indicate an abnormality in the acute suppression of the RAA axis in a substantial proportion of subjects with normal renin essential hypertension. Since previous studies in normal subjects have reported that the early phase of response to saline infusion is related to the sodium ion per se and not to intravascular volume expansion, we have come to the conclusion that the present data are consistent with the hypothesis that the delayed suppression hypertensive group has a diminished ability to respond to the sodium ion.     

Cervical cancer and cytology screening in New Zealand

Cytology screening, used in New Zealand since 1955 at an intensity comparable to that in Canada generally, has not favourably affected incidence and mortality rates for cervical cancer; these have actually risen significantly in 20 to 34-year-old New Zealand women. Canadian claims that mortality falls are related to intensity of cytological screening are not justifiable, so that the significance of the 'pre-cancers' revealed by cytology and the value of population screening would seem to be doubtful.