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Biomedical subjects

B A Davis

Publications and source records attributed to B A Davis.

At least 127 records · Page 7Linked to original sources
PubMed1982

Precursors and metabolites of phenylethylamine, m and p-tyramine and tryptamine in human lumbar and cisternal cerebrospinal fluid.

Phenylacetic acid, p-hydroxyphenylacetic acid, m-hydroxyphenylacetic acid, phenylalanine, indoleacetic acid, 5-hydroxyindoleacetic acid and tryptophan were measured in lumbar and cisternal cerebrospinal fluid (CSF) taken during pneumoencephalography. The data suggest that the concentration of the acid metabolites of the trace amines tryptamine, phenylethylamine, p-tyramine and m-tyramine in lumbar CSF are influenced by the system that transports these acids out of CSF. In cisternal CSF this mechanism does not operate and more information can be obtained on the metabolism of the parent amines in the CNS. Our data indicate that (1) m-tyramine is relatively unimportant quantitatively (2) the rate of metabolism of phenylethylamine in human brain is similar to that of 5-hydroxytryptamine (3) the most important variable controlling the synthesis of phenylethylamine is the activity of aromatic amino acid decarboxylase (4) p-tyramine is synthesised at about half the rate of phenylethylamine and is thus quantitatively important in metabolic terms.

Adolescent↗
PubMed1981

Longitudinal urinary excretion of some "trace" acids in a human male.

Conjugated and unconjugated urinary levels of phenylacetic acid (PAA), m-hydroxyphenylacetic acid (m-HPA) and p-hydroxyphenylacetic acid have been determined for 24-h urine samples obtained from a single healthy male over a 28-day period. Gas chromatographic--electron-capture and mass spectrometric--integrated ion current techniques incorporating appropriate internal standards were used. The average urinary excretion values obtained were (in mg/24 h): PAA unconjugated 0.67, conjugated 96.6; m-HPA unconjugated 7.3, conjugated less than 0.1; p-HPA unconjugated 22.4, conjugated less than 1.2. Following the ingestion of appropriate deuterated amino acid precursors the expected urinary deuterated trace acids were identified and quantitated; in the case of deuterated phenylethylamine, m-HPA and p-HPA as well PAA were identified and quantitated. This is the first evidence of phenylethylamine hydroxylation in the human. The longitudinal excretion of the trace acids was compared with that of the trace amines.

Adult↗
PubMed1981

Pseudo-sulfur granules associated with intrauterine contraceptive devices.

A structure resembling a sulfur granule found in histologic sections of endometrium from patients with intrauterine contraceptive devices is described. It is distinguished from a true sulfur granule on morphologic grounds and is further characterized as a foreign substance, most probably fragments of the synthetic contraceptive device. It is not associated with clinical disease. Microbiologic cultures of removed intrauterine contraceptive devices show no consistent or predominant growth pattern.

Actinomyces↗
PubMed1980

Separation of alkylaminonaphthylenesulfonyl peptides and amin acids by high-performance liquid chromatography. Methods for measuring melanotropin inhibiting factor breakdown.

N,N-Dimethyl diethyl, dipropyl, dibutyl, and N-monoisopropylaminoaphthylenesulfonyl derivatives of melanotropin inhibiting factor (MIF) and its metabolites were prepared, and their chromatographic behavior was investigated with thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), using five solvent systems on polyamide layers and ten solvent systems on muBondapak C18 and muBondapak phenyl columns. A mixture of MIF and its metabolites derivatized with Dns chloride was adequately resolved by two-dimensional chromatography on polyamide layer with solvent systems, formic acid-water (3:97) and benzene-acetic acid (9:1). Bns-MIF and its metabolites were separated with muBondapak C18 column with the solvent system acetonitrile-0.01 M sodium sulphate buffer, pH 7 (50:50). They were separated into five groups: Gly and Bns acid; Pro-Leu, Leu-Gly and Leu; Pro; Gly-NH2; and MIF. The alkylaminonaphthylenesulfonyl derivates had strong fluorescence, which permitted their detection at the level of 10(-11) to 10(-9) mol. Dns-MIF and its derivatives had the lowest detectable amounts. HPLC with the aid of the Dns derivation is reliable and fast, and is the preferable method for study of neuropeptide breakdown.

Alkanesulfonates↗
PubMed1979

Some new fluorescent derivatives for the mass spectrometric quantitation of biogenic amines.

The 5-dimethyl-, diethyl-, dipropyl-, dibutyl-, and dipentyl-aminoaphghalene-1-sulfonyl (dansyl, ethanyl, propansyl, bansyl and pentansyl respectively) derivatives of tyramine and other biogenic amines were prepared and their mass spectra recorded. The relative intensity of the largest unique ion increased with increasing length of the alkyl group. Several O-alkyl-N-propansyl- and N,O-dialkyl-N-propansyl-, bansyl- and pentansyl-tyramines were also synthesized and their mass spectra recorded. Dimethylbansyl- and dimethylpentansyl-tyramines exhibited the largest unique ions in their mass spectra and the greatest sensitivity in quantitation by the integrated ion current method. Procedures for preparing these derivatives in amounts ranging from nanograms to milligrams are presented and their thin-layer chromatographic behavior in three solvent systems is described.

Biogenic Amines↗
PubMed1979

Mass spectrometric identification of Cu, Zn, Fe, Co, Mn, Mg, and Pb in mammalian brain.

Combining the techniques of thin-layer chromatography (TLC) and mass spectrometry, we unambiguously identified the trace metals Cu, Zn, Fe, Pb, Mn, Co, and Mg in the brain of a female human who had no evidence of any pathologic disease in the central nervous system, and in brains from mouse, rat, guinea pig, and rabbit. These trace metals were also found in anatomic regions of human brain: cortex (gray), cortex (white), caudate nucleus, putamen, hippocampus, and thalamus, and in anatomic regions of rat brain: hypothalamus, cerebellum, stem striatum, and "the rest." The metals were characterized from the color and Rf values of their tetraphenylporphyrin chelates on TLC and from the mass and pattern of molecule ion cluster of the mass spectrum. The unexpected presence of lead in the brain is discussed.

Animals↗
PubMed1978

Behavioural treatment of obesity.

Behaviour modification is a promising method of therapy for obesity. Helping the patient to gain control over environmental stimuli and positive reinforcement for the acquisition of appropriate eating and exercise habits are the basis of most treatment programs. While behavioural approaches have, on the average, resulted in greater weight loss than traditional measures during active therapy, responses have been highly variable, and the eventual outcome remains to be established by long-term follow-up studies. The best results are probably achieved with a combination of behavioural therapy and other measures such as a formal exercise program. Since primary prevention may be critical to the overall control of obesity, behavioural approaches may also be applied to young children.

Adult↗
PubMed1977

Gas chromatographic procedure for the determination of meta- and para-hydroxyphenylacetic acids.

m- and p-Hydroxyphenylacetic acids have been identified and quantitated in rat brain by gas chromatography of their pentafluoropropionyl hexafluoroisopropyl diesters. The procedure differs from those employed in earlier studies on the catecholic acids in that a support-coated open-tubular column was used, a preliminary purification of the acids by thin-layer chromatography was carried out, and excess derivatizing reagent was removed by extraction with a phosphate buffer.

Animals↗