Harold L. Rosenthal

Strontium-90 content of deciduous human incisors.

The concentrations of strontium-90 in deciduous incisor teeth of children born in St. Louis between 1949 to 1957 are in accord with estimated bone levels, suggesting that human deciduous teeth are useful as an index of strontium-90 accumulation during the time the teeth are formed.

The resolution of multiple cyanocobalamin-binding components in serum

Abstract At least two major cyanocobalamin-binding sites can be demonstrated in human and animal serum by fractionation on CM-cellulose columns when cyanocobalamin is added in vitro. In normal human serum, Component A, representing 50% of the total binding capacity, is associated with serum albumin and does not bind to CM-cellulose at pH 6. Component B, also representing 50% of the total binding capacity is eluted from the column after the serum globulins at 0.3 M NaCl. Sera from cat, dog, rabbit, horse, cow, pig, sheep, rat, and guinea pig are also resolvable into two major components. The two components in different animal sera are similar but vary with respect to concentration and relative elution pattern. In some animal sera, a third minor cyanocobalamin binding complex (Complex C) is present which is eluted at salt concentrations lower than that necessary for elution of Component B. In chicken serum, Component B is entirely absent. Sera of dogs, rabbits and chickens given oral doses of high specific activity [57Co]cyanocobalamin, followed by fractionation on CM-cellulose columns, yield cyanocobalamin binding sites essentially similar to that found for cyanocobalamin added to serum in vitro.

Isolation of a component from commercial Coomassie Brillian Blue R-250 that strains rubrophilin and other proteins red on polyacrylamide gels

Commercially available Coomassie Brilliant Blue R-250 (C.I. 42660) is a popular and useful dye that stains most proteins blue on polyacrylamide gels. Some proteins from brain (rubrophilin), collagens, histones and parotid gland proteins are distinctly red when stained with Coomassie Blue. Commonly used Coomassie Brilliant Blue R-250 preparations may contain more than 30 distinct colored and fluorescent components that can be separated on silica gel chromatographic columns. A specific component has been isolated on silica gel columns that stains rubrophilin and other proline-rich proteins a reddish color. Fast atom bombardment mass spectrometry of the isolated rubrophilin staining principle indicates a molecular weight of 634 as compared to 826 for the major dye in the original Coomassie Brilliant Blue R-250. Infrared spectrometry is consistent with a difference between the rubrophilin staining principle and Coomassie Brilliant Blue R-250 of a toluene sulfonic acid residue.

Purification and properties of rubrophilin: a novel brain specific membrane polypeptide.

Abstract: Rubrophilin, a unique brain specific polypeptide, was purified to apparent homogeneity from microsomal fractions of bovine brains. The peptide stains pink with Coomassie Brilliant Blue R‐250 (C.I. No. 42660) under specific conditions, has an apparent Mr of 53,000, and is acidic with an apparent pI of 4.9. The purification involves initial solubilization of delipidated microsomes in sodium dodecyl sulfate, followed by ammonium sulfate fractionation, reversed ammonium sulfate gradient elution from diatoma‐ceous earth, gel filtration on polyacrylamide (Biogel P‐200). gradient elution chromatography from hydroxylapatite, and reverse‐phase chromatography from phenyl‐Sepharose. A yield of about 5 mg of rubrophilin was obtained from 9 g of microsomal proteins. Amino acid analysis shows that rubrophilin contains only nine amino acids with residues/ mol as follows: alanine (102), glutamic acid (97), lysine (65), proline (55), aspartic acid (48), glycine (44), serine (37), threonine (35), and valine (10). Cysteine, methionine, tryp‐tophan, tyrosine, isoleucine, phenylalanine, histidine, and arginine could not be detected. Relative rubrophilin content of vertebrate brains was as follows: mammals > birds > reptiles > fishes. It is present in mouse retina and human neu‐roblastoma cell cultures but could not be detected in octopus optic lobe or in cultured C‐6 rat glioma cells.

Serum vitamin B12 content and UBBC in gravid and fetal rabbits.

It is well known that human serum vitamin B12 decreases progressively during pregnancy (1-3) with lowest levels present at term. Within 4-6 weeks post partum, the maternal serum B12 level returns to normal or higher (4-5). In general, fetal cord blood contains more vitamin B12 than comparable maternal blood (3). The unsaturated vitamin B12 binding capacity (UBBC) of the mother increases during pregnancy and returns to normal within a month of parturition (6, 7). Similar phenomenon have also been found in rats (1). Although pregnant women and gravid experimental rats appear to follow the same pattern with regard to serum vitamin B12, no definitive rationale has as yet been offered to explain these effects. Rabbits are known to contain the highest serum vitamin B12 content and UBBC of all laboratory mammals so far tested (8). Because rabbits are often used as models for fetal development, it was of interest to determine the serum B12 and UBBC during gravidity and in the fetus. Materials. Samples. Sera of gravid New Zealand rabbits, fetuses near term and sera of both sexes during growth and development were obtained commercially.1 Sera from New Zealand strain rabbits that were maintained in the laboratory were used for comparative purposes. Sera of normal pregnant women were obtained a few hours prior to parturition and cord blood was obtained from their normal healthy infants. All sera were maintained frozen at −20° until analyzed. Vitamin B12 assay. Vitamin B12 was determined by a competitive binding assay using porcine intrinsic factor (IF)2 as the binding protein, high specific activity 57Co labelled cyanocobalamin (15 μCi/μg B12-60 μCi/μg B12)3 and equilibrium dialysis briefly described as follows: Dilute 10 μl of rabbit serum (or use 0.5 ml of undiluted human serum) to 0.5 ml with saline.