Rat brain monoamine levels related to behavioral assessment.

Randomly selected adult, male, Sprague-Dawley rats exhibit a range of behaviors in an open field. Exploration without defecation or urination is interpreted as stable behavior. On the basis of their open field behavior we selected the five most "emotional" and five most "stable" rats from two separate groups of thirty rats. Norepinephrine (NE), dopamine (DA), and serotonin (5HT) levels were determined in brains from these ten "emotional" and ten "stable" rats. The NE levels of "emotional" rats were elevated about 60 ng/g relative to the "stable" rats. There was no difference in DA levels, but there appeared to be a trend toward elevation of 5HT levels in the "emotional" rats. These findings directly support the hypothesis that elevated central nervous system norepinephrine levels may reflect a factor which contributes to emotionality in the rat, and suggest that brain norepinephrine levels may be a biochemical mechanism which influences performance as seen with the commonly used open field behavioral test of emotionality.

Isolated, ventilated, perfused newborn rabbit lung preparation and its assessment.

To achieve an isolated, ventilated, perfused newborn rabbit lung preparation, newborn rabbits are anesthetized and ventilated. The pulmonary vasculature is perfused with a Krebs-Ringer bicarbonate solution containing glucose and plasma expanders, and the lungs are isolated in a 37 degrees C chamber at 100% humidity. The success of a perfusion is evaluated on three levels. 1) Visual. 2)mechanical: a, drop in flow of greater than 20% indicates failure; b, an increase of more than 25% of the initial lung weight indicates fluid accumulation and failure. 3) Biochemical: a, the endogenous ATP concentration after perfusion; b, the level of the enzyme choline phosphotransferase (CPT) after perfusion. Isolated, perfused, ventilated newborn rabbit lungs maintained for 4 h with no changes in the monitored physical and mechanical parameters have an endogenous ATP level of 1.06 +/- 0.06 (2 SD) mumol ATP/mg wet weight and a CPT level of 1.34 +/-0.15 (2 SD nmol [14C]CDP-choline per milligram protein in 30 min. These values are stable at a level lower than observed in intact, hypoxic, newborn rabbit's lungs. In constrast, if perfusion is maintained after any of the monitored criteria indicate failure, the endogenous ATP concentration and CPT activity are significantly depressed.

The use of amniotic fluid bubble stability, L/S ratio, and creatinine concentration in the assessment of fetal maturity.

Amniotic fluid bubble stability and creatinine concentration are analyzed in relation to the L/S ratio and clinical outcome. Bubble stability by the standard method showed 20.5 per cent (31/151) initial disagreement between two laboratories, 53.6 per cent (81/151) correlation with L/S ratio, and did not correlate well with patient outcome. However, a "foamy" test, i.e., foam noticeable at a distance, in both 1:1 and 1:2 dilutions, indicated an elevated L/S ratio and mature pulmonary outcome. Amniotic fluid creatinine levels showed an estimated 5 to 6 per cent risk for RDS at levels we formerly thought to be safe (greater than or equal to 2.0 mg. per 100 ml. with maternal serum less than or equal to 0.9 mg. per 100 ml.), and has many false-negative values. Fetal maturity can be estimated with clinical data and amniotic fluid analysis. Amniotic fluid sampling is necessary in all instances where the clinical data leave a reasonable doubt of actual gestational age and in all cases for elective preterm delivery. We recommend a sequential approach to amniotic fluid analysis. First a bubble stability test (a "foamy" at both 1:1 and 1:2 dilutions indicates pulmonary maturity). If the bubble stability test is not "foamy", an L/S ratio. The risk of RDS associated with creatinine concentration makes this test unacceptable in any case of elective delivery; however, it may be useful as a weighing factor in emergency situations where phospholipid analysis is unavailable.