Serum concentrations of cortisone and cortisol in premature infants.

To determine the relationship between biological active cortisol and its inert metabolite cortisone accurately in premature infants, serum cortisone and cortisol concentrations were measured by reversed-phase high-performance liquid chromatography (HPLC) in a group of 232 premature infants and in a control group of 127 children and 88 adults. In the control group, serum cortisone concentrations were greater than serum cortisol levels during the first 2 months after birth; cortisol levels were higher than cortisone levels after 2 months of age. However, in premature infants, serum cortisone concentrations were greater than serum cortisol levels even after the first 2 months, and total concentrations of cortisone and cortisol were equal to those in controls. Results were then analyzed according to the equivalent gestational age of premature infants. Cortisone was predominant in premature infants older than 32 weeks of equivalent gestational age, but cortisol was higher than cortisone from equivalent gestational age 24 to 31 weeks. These findings suggest that the ability of premature infants to secrete glucocorticoids resembled that of normal controls. Also, the fetal zone of the cortex, which is associated with a predominance of cortisone, remained functional in premature infants for a longer time than in control infants. Our findings that in premature infants cortisone was predominant compared with cortisol and the sum of cortisone and cortisol was equal to that in the controls indicate that cortisone cannot be disregarded whenever the cortisol level is estimated, although cortisone itself is recognized to be biologically inactive. Simultaneous measurement of serum cortisone and cortisol concentrations is important when adrenocortical function is being determined, especially in premature infants.

Muscle activities in the hand and arm during tooth brushing and the regulation of brushing movements by oral sensory perception.

Investigations were made of the forces during brushing of the teeth, the patterns of brushing movements, and muscle activities, with and without blockage of sensory perception in the oral cavity, while each subject brushed by the rolling method, scrubbing method, and by his own individual habitual brushing method. We learned from electromyograms that the scrubbing method primarily used the muscles of the palm of the hand and the forearm, while the rolling method cleaned principally by action of the muscles of the upper arm and shoulder. With the rolling method, the rhythmic pattern of the brushing movement and muscle activity were lost when sensory perception in the oral cavity was blocked and, in those subjects who had a low periodontal membrane tactile threshold, the brushing force was greater than when sensory perception was not blocked. However, no effect was observed with blockage of the sensory perception in the oral cavity when the scrubbing method was used. Since brushing movements with the scrubbing method resemble the movements of writing, we also carried out investigations on the relationship between the forces during writing and brushing. As a result we found that with the scrubbing method, the brushing forces were strong for the subjects who had strong writing forces, while they were weak for those with weak writing forces. It was clear from the above results that the force of brushing with the rolling method was affected more by factors relating to oral sensory perception than muscle activity, while with the scrubbing method it was affected more by factors relating to muscle activity of the palm of the hand and forearm than by oral sensory perception. There was a clear difference in the brushing forces, pattern of brushing movements, and muscle activity between experienced and inexperienced subjects with both the scrubbing and rolling methods. Thus we learned that the effect of brushing instructions could be evaluated not only by the efficiency of plaque removal, brushing force or skill of brushing movements, but also by muscle activity. The phenomena observed with the scrubbing and rolling methods were not seen with the subjects' individual habitual brushing method.

Intracellular localization and characterization of 3-hydroxykynureninase in human liver.

3-hydroxykynureninase in human liver was present in cytosol and mitochondria. The cytosolic enzyme and mitochondrial enzyme had the same physiological and enzymic properties. The enzyme had a mol. wt of 130,000 by gel filtration and isoelectric point of pH 5.9. The enzyme was active for 3-hydroxykynurenine and kynurenine, and its activity ratio was 15:1. The apparent Km values of the enzyme were 7.7 X 10(-5) M for 3-hydroxykynurenine, 1.0 X 10(-3) M for kynurenine and 2.5 X 10(-6) M for pyridoxal 5'-phosphate with 3-hydroxykynurenine. Some other properties of purified enzymes are described.

Purification and characterization of amino-acid N-choloyltransferase from human liver.

Amino-acid N-choloyltransferase was purified from human liver. The procedure resulted in about 100-fold enriched activity and glycine- and taurine-dependent activities co-purified and did not separate to any extent in any of the steps. The final enzyme preparation had an apparent molecular mass of 100 kDa by gel filtration, 118 kDa by sucrose density gradient centrifugation and was composed of two identical subunits which had a molecular mass of 52 kDa, as judged by dodecyl sulfate polyacrylamide disc gel electrophoresis. The glycine- and taurine-dependent activities showed optima at pH 7.2 and pH 6.5, respectively. Apparent Km values of purified enzyme were 3.2 and 0.6mM for glycine and taurine, respectively. The Km value for choloyl-CoA was 50 microM for the glycine-dependent activity and 87 microM for the taurine-dependent activity. Bile acid derivatives and cholesterol had an inhibitory effect on both glycine- and taurine-dependent activity in vitro; on the other hand, the reaction was stimulated by the addition of glutathione, EDTA and L-cysteine. Amino acid substrate specificity was restricted to glycine, taurine, beta-alanine and D-alpha-alanine. As well as choloyl-CoA, its deoxy derivatives were also good substrates for the enzyme.