Salivary caffeine and neonatal behavior: assay modification and functional significance.

A radioimmunoassay (RIA) was developed for the quantification of caffeine in saliva. The mean salivary caffeine level for this sample of 40 full-term, AGA, healthy 1-2 day old human neonates was consistent with levels reported in previous studies. Salivary caffeine was significantly correlated with the number of state changes and startles observed during administration of the Brazelton Neonatal Behavior Assessment Scale. There was also a nonsignificant trend correlating salivary caffeine with visual orienting and consolability.

Intrinsic factor, free of R proteins, can be prepared from mouse stomach and used in a ligand assay specific for "true" cobalamin.

A ligand assay specific for cobalamin that uses mouse stomach as the source of intrinsic factor has been developed. When mouse stomach extract incubated with radiocobalamin is fractionated by gel chromatography, the radioactive complex elutes as a single peak with apparent molecular weight of 54,900. Formation of the complex is greater than 98% inhibited by human anti-intrinsic factor antibody. When the equivalent of 10,000 pg/ml of cobinamide is added to serum, the apparent cobalamin concentration detected averages 8.5 pg/ml. Correlation with the Lactobacillus leichmannii microbiologic assay results in the regression equation y = 0.97x + 20. In six patients who had megaloblastic anemia the serum cobalamin by the mouse intrinsic factor ligand assay ranged from 0 to 9 pg/ml. Because the primary source of intrinsic factor is free of R proteins, there is no need for extensive purification of the extract. The assay is sensitive, precise, and accurate, and no more difficult to perform than other conventional ligand assay procedures.

Leucomalachite green assay for free hemoglobin in serum.

A new colorimetric assay for the determination of serum free hemoglobin utilizing the noncarcinogenic compound leucomalachite green is described. The reaction is complete in 8 min, with the resulting color stable for at least 30 min. The absorption maximum for the leucomalachite green reaction product was observed at 617 nm. Precision studies at 50 and 300 mg/l free hemoglobin concentrations resulted in within-run variations of 1.9 and 1.7%, while the day-to-day variations were 6.9 and 4.0%, respectively. Accuracy studies at concentrations of 50, 150 and 300 mg/l resulted in recoveries of 88, 95 and 98% of theoretical values.

A supplement to alkaline phosphatase fractionations: utilization of gamma-glutamyl transpeptidase and hydroxyproline assays.

Fractionation of serum alkaline phosphatase by either biochemical or electrophoretic techniques is often insufficient to determine the source of the elevated serum enzyme. In 31 unselected patients with high serum alkaline phosphatase a simultaneous determination of serum gamma glutamyl transpeptidase and urinary hydroxyproline excretion rates was performed, in addition to urea denaturation and L-phenylalanine inhibition tests. Of 25 patients with definite diagnosis, the urea denaturation test correctly identified the source of the elevated serum alkaline phosphatase (ALP) in 16 (64 percent). The serum gamma-glutamyl transpeptidase (GGTP) alone predicted the correct diagnosis in 64 percent of the cases and the urinary hydroxyproline (HOP) alone in 69 percent. When all three tests were performed simultaneously, the combination of results identified the source of the ALP in 88 percent of the cases. It is believed that this combination offers better sensitivity and specificity than any of the three tests used individually.