Infant temperament and the brainstem auditory evoked response in later childhood.

Brainstem auditory evoked responses (BAERs) were evaluated on 10-12-year-old children (N = 56) who had been classified as high or low reactive to unfamiliar stimuli at 4 months of age. BAER measurement was selected because high reactive infants tend to become inhibited or fearful young children, and adult introverts have a faster latency to wave V of the BAER than do extroverts. Children previously classified as high reactive at 4 months had larger wave V components than did low reactive children, a finding that possibly suggests greater excitability in projections to the inferior colliculus. The fact that a fundamental feature of brainstem activity differentiated preadolescent children belonging to two early temperamental groups supports the value of gathering physiological data in temperament research.

Elevation in late-life depression of intercellular adhesion molecule-1 expression in the dorsolateral prefrontal cortex.

OBJECTIVE: Late-life depression may be associated with vascular disease. The authors investigated this association by determining whether intercellular adhesion molecule-1 (ICAM-1), a marker of ischemia-induced inflammation, is elevated in the dorsolateral prefrontal cortex in depression. METHOD: The authors studied postmortem tissue from 20 depressed subjects and a matched comparison group of 20 nondepressed subjects. They used immunocytochemistry to stain ICAM-1 in blood vessels on sections of the dorsolateral prefrontal cortex and occipital cortex and quantitative true color image analysis to measure the proportion of vessels expressing ICAM-1. RESULTS: ICAM-1 was significantly higher in both the gray and white matter of the depressed subjects' dorsolateral prefrontal cortex than the comparison subjects' dorsolateral prefrontal cortex. The difference between these groups was much smaller in the gray and white matter of the occipital cortex. CONCLUSIONS: These findings support the vascular depression hypothesis, which has important implications for the understanding and management of late-life depression.

Taxonic structure of infant reactivity: evidence from a taxometric perspective.

Previously, we proposed a theoretical framework that classified infants into qualitative categories of reactivity, rather than on a continuous dimension. The present research used an objective statistical procedure (maximum covariance analysis, or MAXCOV) to determine if a qualitative latent structure, consistent with our theoretical conjectures, would be found to underlie quantitative indices of reactivity to stimuli in a sample of 599 four-month-old infants. Results of the MAXCOV analysis showed clear evidence of a latent discontinuity underlying the behavioral measures of infant reactivity. The base rate of the latent class (or taxon) was estimated at 10%. Infants within the putative high-reactivity taxon, compared with infants not in the taxon, were elevated on measures of behavioral inhibition at 4.5 years. These results provide objective empirical support for a central tenet in our theoretical model by supporting the taxonicity of infant reactivity.

Some observations on the influence of vitamin D metabolites when added to the diet of commercial laying hens.

Three experiments were conducted to study the influence of two vitamin D3 metabolites on the performance of commercial laying hens. In Experiment 1, adding of .75, 1.50, 3.00, and 4.50 micrograms of 1 alpha-hydroxycholecalciferol (1 alpha-OHD3) or of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] per kg to the diet containing 2,200 ICU of vitamin D3 from 55 micrograms of cholecalciferol per kg of diet resulted in increased plasma calcium (Ca) and phosphorus (P). The response was greater from the 1,25-(OH)2D3 metabolite than from the 1 alpha-OHD3 metabolite. Neither metabolite affected tibia breaking strength (TBS), egg production (EP), egg weight (EW), feed consumption (FC), feed conversion, eggshell quality (ESQ), fertility, or the hatchability of eggs or the tibia ash (TA) of the day-old chick. In Experiment 2, the EP, EW, FC, ESQ and TA of the hens were not affected when 1.5 micrograms of 1,25-(OH)2D3 were added to each kilogram of a corn-soybean meal diet containing either .38 or .43% P with adequate vitamin D3. Adding the 1,25(OH)2D3 metabolite to the low-P diet reduced plasma Ca and increased TBS. However, adding 1,25-(OH)2D3 to the high-P diet increased plasma Ca and P. In Experiment 3, the EP, ESQ, FC, and TA of the hens were significantly lower when the diet contained 2.04% Ca rather than 3.04% Ca. Plasma Ca and P, EW, or TBS were not affected by the dietary Ca. Neither the plasma Ca and P, EP, EW, ESQ nor the TBS and TA were influenced by adding the 1,25-(OH)2D3 metabolite to either diet.

Influence of Virginiamycin on yield of broilers fed four levels of energy.

An experiment was conducted to determine the effect of dietary Virginiamycin on processing yields of broilers fed four levels of energy. Body weights (catch, slaughter) and carcass weights (dry shell and ready-to-cook) were recorded. Shrink (holding weight loss), water uptake, shell yield, and ready-to-cook yield of the carcasses were calculated. Body weights were higher at higher energy levels and with addition of Virginiamycin to the diets. Weight loss due to shrink declined from 5.39 to 3.89% at higher dietary energy levels, but shrink was not affected by Virginiamycin. Water uptake was significantly higher for carcasses of birds fed the lowest dietary energy level (3.49%) than for carcasses of birds fed the two highest energy levels (2.89 and 3.03%); but differences among water uptake of carcasses of birds fed the three highest energy levels were not significant. Water uptake was unaffected by Virginiamycin. Increasing the dietary energy level resulted in higher ready-to-cook yields, from 61.7% yield at 2,271 kcal ME/kg to 65.4% yield at 2,953 kcal ME/kg. Yield was increased from 63.3 to 64.0% (P less than .01) by dietary Virginiamycin.

Influence of Florida 301 wheat in a laying hen diet on egg yolk rupture strength.

A study was designed to determine whether wheat could be substituted for corn without reducing yolk quality and yolk membrane strength. Diets with either corn or Florida 301 wheat as the grain source were fed to 50-wk-old hens (140 per diet). Eggs were collected and stored at 10 C for up to 4 wk or at 23 C for 1 wk. At weekly intervals Haugh units, yolk index, yolk rupture strength, and yolk deformation distance at rupture were measured and compression percentages were calculated. Haugh units and yolk index were not affected by diet. Yolk rupture strength and deformation were 12.3% and 4.7% greater, respectively, for eggs from hens on the wheat diet than for those from hens on the corn diet. Both rupture strength and deformation declined significantly with storage. Eggs stored at 23 C were lower in yolk rupture strength and deformation than those held at 10 C. Percentage of compression at rupture also declined with storage, but the decline was initially more rapid for egg yolks from birds fed the corn diet than for egg yolks from birds fed the wheat diet. It was concluded that Florida 301 wheat may be substituted for corn without incurring any problems in the quality of the yolk and that yolk breaking strength would be enhanced.