Measurement of whole blood serotonin as a guide in prescribing psychostimulant medication for children with attentional deficits.

A retrospective study was made of a series of 73 children who presented at the Diagnostic and Developmental Center, Northbrook, IL, U.S.A. between February 1, 1983 and July 1, 1984 with learning disabilities, impulsivity, short attention span, and in some cases, hyperactivity as well. Ninety-eight percent of the patients with low whole blood serotonin levels (below 90 ng/ml) improved in their ability to pay attention and learn and diminished in impulsivity when the psychostimulant medication pemoline was administered, while the patients with higher levels (above 100 ng/ml) did not benefit from the drug. Thus, the measurement of serotonin levels in whole blood appears to have predictive value as to which children can be helped by treatment with pemoline. Based on the data presented, we recommend the use of the whole blood serotonin test at the time of initial evaluation to determine whether children should be treated with pemoline, thereby sparing those who would not respond favorably from an ineffectual trial of the drug.

Estrogen radioimmunoassay suitable for the monitoring of ovulation induction.

A rapid radioimmunoassay for estrogen in serum was characterized and validated. Analytical recoveries of estrone and estradiol were essentially 100%; estriol was not measured because it was eliminated by sample-handling procedures. Nonspecific interference from serum extracts, which was initially reflected by positive blanks, was eliminated by a sodium hydroxide wash of the extract. Validation of the procedure included determination of a reference interval for estrogen that agreed with the sum of estradiol and estrone concentrations reported in the literature for eugonadal women. Clinical applicability of the assay was demonstrated by monitoring estrogen concentrations during the menstrual cycle and during urogonadotropin (Pergonal)-induced follicular maturation. Because of its rapid turnaround time, the assay is ideally suited for monitoring the frequency with which urogonadotropin should be administered to the infertile patient, and the dosage, thus decreasing the likelihood of multiple pregnancies or ovarian hyperstimulation.

Measurement of three aminoglycosiee antibiotics with a single radioimmunoassay system.

A versatile radioimmunoassay procedure has been developed to specifically assay gentamicin, tobramycin, or amikacin. Iodinated derivatives of these three antibiotics were prepared by a modified Bolton and Hunter procedure. A single reagent system composed of a pool of three very specific antisera was used in the procedure. The antisera combination did not alter the specificity of the procedure. Validation of the assay of the three antibiotics included studies of parallelism, accuracy, precision, reproducibility, and method comparison with other radioimmunoassay procedures involving single antiserum systems. We discuss the application of this multiple assay capability to other procedures involving use of immunochemicals.

Phosphorylation of ribosomal proteins in rat cerebral cortex in vitro.

Incubation of cerebral cortical tissue from immature rats in the presence of [32P]orthophosphate resulted in similar rates of incorporation of radioactivity into the proteins of free and membrane-bound ribosomes. Incorporation of label into ribosomal proteins of both species continued actively for at least 3 hours. Since recovery of membrane-bound ribosomes from rat cerebral cortex is quite low, further analyses of the radioactive phosphoproteins were restricted to the free ribosome population. A significant fraction of the radioactivity which was precipitated with trichloroacetic acid was not removed by heating in trichloroacetic acid at 90 degrees or extracted with organic solvents and therefore was presumed to be covalently bound to protein. The radioactive phosphoryl groups present in the ribosomal proteins were mainly in ester linkages since they were readily removed by exposure to 1 N NaOH, relatively unaltered by 1N HCl, and unaffected by hydroxylamine. This conclusion was supported by the isolation of labeled o-phosphoserine and o-phosphothreonine residues from hydrolysates of ribosomal proteins. A significant fraction of the labeled phosphoproteins in the purified ribosomes appeared to be bound tightly to the ribosome structure since only 40% of the radioactivity could be removed by extraction of these ribosomes with 1 M KCl. Phosphorylation of proteins of cerebral monoribosomes was more rapid than the same process in polyribosomes from the same source. Eight radioactive phosphoprotein bands could be detected by electrophoresis of proteins obtained from unfractionated cerebral ribosomes on unidimensional polyacrylamide gels containing sodium dodecyl sulfate. The protein nature of these materials was confirmed by pronase digestion. Proteins of subribosomal particles isolated from the total free ribosomal population were labeled differentially. When dissociation was carried out in the presence of EDTA, the small subunit contained four radioactive phosphoprotein bands, whereas the large subunit contained five. Three of the radioactive phosphoprotein components of the small subunit were removed when dissociation of cerebral ribosomes which were previously washed with high salt media was carried out in the presence of puromycin and high salt. However, only the largest labeled phosphoprotein band of the large subunit was removed by this procedure. This component exhibited the same electrophoretic mobility as one of the radioactive phosphoprotein bands which was removed from the small subunit by high salt treatment..