John E. Christian

Bio: John E. Christian is an academic researcher from Purdue University. The author has contributed to research in topics: Excretion & Isotope dilution. The author has an hindex of 16, co-authored 168 publications receiving 1021 citations. Previous affiliations of John E. Christian include Philips.

Body composition: relative in vivo determinations from potassium-40 measurements.

Abstract: Measurements of body composition from serial, in vivo determinations of potassium-40 were made on 51 obese human subjects who were placed on a low calorie diet. Weight losses in the group averaged from 12 to 36 pounds. There was no change in potassium content or in lean body weight. Weight loss resulted from the loss of excess body fat.

A Note on the Application of Radioactive Isotopes to Studies of Drug Deterioration

Abstract: A method of electrophoretic separation and identification was developed for the products of the thermal degradation of acetylsalicylic acid. The procedure, however, as used in this work was not quantitative. Experiments were performed to determine the progress of the thermally increased hydrolysis of acetylsalicylic acid by means of radioisotope tracer techniques. The use of radioisotopic tracers as a method of stability study was shown to have the advantages of being able to detect the most minute amounts of breakdown products, even in complex mixtures. It is also possible to determine the rate of breakdown without identifying the breakdown products or knowing the mechanism of degradation.

Relationships between physical performance items and body composition.

Abstract: The purpose of the study is: (a) to determine the relationships between body composition and physical peformance and related items; and (b) to determine whether or not certain physical performance and related items might be useful in estimating body composition in terms of total lean body mass and percent lean body mass as measured by potassium-40 determinations in adult men. Data on 19 physical performance items were obtained from 40 subjects between 21 and 57 years of age. The results are of value to researchers in general and researchers in physical education in particular for estimating gross body composition using certain physical performance items.

Distribution of sulfur-35- and gold-198-labeled gold thioglucose in mice.

Abstract: Radioactive gold thioglucose was prepared using gold-198 and sulfur-35. It was administered in normal saline solution to female Rockland Swiss mice between 4 and 5 weeks of age and weighing approximately 20 gm. The labeled compound was given at a dose of 1 mg/gm of body weight and the radioactive dose was 0.2 uc/gm. The distribution of the labeled compound was determined at intervals of 30 minutes, 2, 6, 18 and 48 hours. The hypothalamic levels of radioactivity of mice treated with both sulfur-35- and gold-198-labeled gold thioglucose were significantly greater than those of the hindbrain and cerebrum at all time intervals with the exception of the hindbrain at 30 minutes. Autoradiographs of mice treated with gold-198-labeled material showed a localization of radioactivity in the diencephalon, which contains the hypothalamus. The kidney had the highest concentration of both labeled compounds at 30 minutes, and adrenal values were close to those of the kidney. Lesser degrees of radioactivity were found in the spleen, liver, muscle and blood.

Quantification of proteins and metabolites by mass spectrometry without isotopic labeling or spiked standards

Abstract: A new method is presented for quantifying proteomic and metabolomic profile data by liquid chromatography−mass spectrometry (LC−MS) with electrospray ionization. This biotechnology provides differential expression measurements and enables the discovery of biological markers (biomarkers). Work presented here uses human serum but is applicable to any fluid or tissue. The approach relies on linearity of signal versus molecular concentration and reproducibility of sample processing. There is no use of isotopic labeling or chemically similar standard materials. Linear standard curves are reported for a variety of compounds introduced into human serum. As a measure of analytical reproducibility for proteome and metabolome sampling, median coefficients of variation of 25.7 and 23.8%, respectively, were determined for ∼3400 molecular ions (not counting their numerous isotopes) from 25 independently processed human serum samples, corresponding to a total of 85 000 individual molecular ion measurements.

Determination of carbon-14 in aqueous bicarbonate solutions by liquid scintillation counting techniques. application to biological fluids

Abstract: Using Cellosolve as a solubilizing additive, up to 5.84 ml of aqueous bicarbonate solutions and essentially equivalent amounts of urine and plasma containing carbon-14- sodium carbonate can be assayed by liquid scintillation counting techniques. Of particular significance is the realization of determining carbon-14 activity with relatively high efficiency in the important biological fluids. (auth)

Suitability of urethane anesthesia for physiopharmacological investigations in various systems. Part 1: General considerations.

Abstract: The suitability of urethane anesthesia for physiopharmacological investigations is reviewed. Total dose administered and route of administration are recognized as factors having a great influence on both resting parameters and biological responses to drugs. A peculiar characteristic of urethane is represented by its ability to induce a surgical plane of anesthesia without affecting neurotransmission in various subcortical areas and the peripheral nervous system. This makes urethane a suitable general anesthetic for studying neural function in both central and peripheral nervous systems and accounts for the preservation of a number of reflex responses in urethane-anesthetized animals.

Chlorinated Phenols: Occurrence, Toxicity, Metabolism, And Environmental Impact

Abstract: (1980). Chlorinated Phenols: Occurrence, Toxicity, Metabolism, And Environmental Impact. CRC Critical Reviews in Toxicology: Vol. 7, No. 1, pp. 1-35.