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Biomedical subjects

G E Gaull

Publications and source records attributed to G E Gaull.

At least 19 recordsLinked to original sources
PubMed1989

Taurine in pediatric nutrition: review and update.

Taurine was long considered an end product of the metabolism of the sulfur-containing amino acids, methionine and cyst(e)ine. Its only clearly recognized biochemical role had been as a substrate in the conjugation of bile acids. Taurine is found free in millimolar concentrations in animal tissues, particularly those that are excitable, rich in membranes, and generate oxidants. Various lines of evidence suggest one major nutritional role as protecting cell membranes by attenuating toxic substances and/or by acting as an osmoregulator. The totality of evidence suggests that taurine is nonessential in the rodent, it is an essential amino acid in the cat, and it is conditionally essential in man and monkey. Absence from the diet of a conditionally essential nutrient does not produce immediate deficiency disease but, in the long term, can cause problems. Taurine is now added to many infant formulas as a measure of prudence to provide improved nourishment with the same margin of safety for its newly identified physiologic functions as that found in human milk. Such supplementation can be justified by the finding of improved fat absorption in preterm infants and in children with cystic fibrosis, as well as by salutary effects on auditory brainstem-evoked responses in preterm infants. Experimental findings in animal models and in human cell models provide further justification for taurine supplementation of infant formulas.

Humans↗
PubMed1987

Taurine conjugation of bile acids protects human cells in culture.

The primary trihydroxy bile acid, cholate, both free and conjugated, is nontoxic in cultured human lymphoblastoid cells incubated in vitro. The primary dihydroxy bile acid, chenodeoxycholate, was more toxic at high concentrations than at low concentrations, but conjugation with taurine reversed it. The free secondary bile acids, deoxycholate and lithocholate, corresponding respectively to cholate and chenodeoxycholate, are extremely toxic, the latter more than the former. Conjugation with taurine reversed the toxicity, as did glycine. Neither free taurine nor free glycine added to unconjugated bile acids decreased toxicity.

Bile Acids and Salts↗
PubMed1986

Protein quantity and quality in term and preterm infants: effects on urine creatinine and expression of amino acid excretion data.

The effect of dietary protein quantity and quality on the excretion of creatinine in preterm and term neonatal infants has been investigated. Whey protein predominant formulas result in increased creatinine excretion as compared with either casein protein predominant formulas or with pooled human milk in preterm infants (p less than 0.001 by ANOVA). The volume of human milk (170 versus 185 versus 200 ml/kg/day) appears to have little effect in these infants. In term infants, few differences among the feeding groups were observed, although creatinine excretion did increase with time. The pattern of creatinine excretion among feeding groups was similar regardless of whether or not the data were expressed in milligrams per deciliter or in milligrams per 24 hours. Small correlations of creatinine excretion with birth weight were observed, but these appeared to vary, depending on the type of feeding. These diet-induced differences in creatinine excretion indicate the need for caution in expressing other urinary metabolites, such as amino acids, relative to creatinine excretion.

Amino Acids↗
PubMed1985

Stable isotope study of plasma taurine kinetics in rhesus monkey.

Taurine is one of the most abundant amino acids in mammals and there is increasing evidence for the importance of taurine during development. Plasma taurine kinetics in a rhesus monkey was studied using [1,2-13C2]taurine. Taurine in plasma was derivatized to its dimethylaminomethylene methyl ester, separated on a gas chromatographic column, and the [M+2+H]+/[M+H]+ ion ratio was measured by ammonia chemical ionization mass spectrometry. The results were comparable to those obtained from the simultaneous radioisotope tracer study using [35S]taurine. This stable isotope method requires only 200 microliters of plasma for precise and accurate determination and is suitable for taurine kinetic studies in human infants.

Animals↗
PubMed1985

Methionine intolerance: a possible risk factor for coronary artery disease.

Homocystinuria, an inherited disorder associated with premature atherosclerosis, represents a severe form of methionine intolerance. To analyze the importance of milder forms of methionine intolerance in the genesis of vascular disease, the relation between provokable methionine intolerance and coronary artery disease was investigated. In a group of 138 men, aged 31 to 65 years (mean 53), referred for cardiac catheterization, plasma homocystine was measured before and 6 hours after an oral l-methionine load (0.1 g/kg). Thirty-nine subjects found to have normal coronary arteries had a mean post-load plasma homocystine level of 0.59 +/- 0.37 mumol/liter. A criterion at the 95th percentile (1.64 SD above the mean) was selected and applied to the remaining 99 subjects with coronary artery disease (0.70 +/- 0.68 mumol/liter). Sixteen (16%) of 99 subjects with coronary artery disease exceeded this level as compared with 1 (2%) of 39 subjects without coronary artery disease (p less than 0.04). The risk of coronary artery disease in men with provokable methionine intolerance was increased sevenfold as estimated by the odds ratio. By correlation matrix and multivariate regression analyses, provokable homocystinemia was predictive of coronary artery disease and was independent of tobacco smoking, hypertension, diabetes mellitus, serum cholesterol and age. It is proposed that men with mild methionine intolerance exposed to the high methionine content of the Western diet may develop intermittent homocystinemia and thus may be at greater risk for the development of coronary artery disease.

Adult↗
PubMed1985

Biopterin and neopterin in various milks and infant formulas.

Biopterin and neopterin concentrations were measured by reverse-phase high pressure liquid chromatography in milks of man, cow, rabbit, cat, and rat and in commercial formulas widely used in North America. There was wide variation of concentration among species. Higher concentrations of biopterin were present in human milk (392.0 +/- 158.6 pmol/ml) than were present in all milk formulas analyzed (2.6-50.6 pmol/ml).

Animals↗
PubMed1985

Significance of growth modulators in human milk.

Human milk contains growth modulators of potential clinical importance to the neonate. Evidence from animal and cell culture models as well as ancillary evidence about their stability and the way some of them are processed for secretion suggest they are probably physiologically significant. Their presence in human milk does not by itself establish their importance; however, it is useful to explore their potential functional roles. Growth modulators present in human milk include: EGF, NGF, certain enzymes, and taurine.

Animals↗
PubMed1984

Sulfhydryl oxidase in human milk: stability of milk enzymes in the gastrointestinal tract.

Sulfhydryl oxidase (SOX) is present in human milk and in milk from all species that have been studied. The pH optimum of human milk SOX is in the neutral range between 7.0 and 7.5. Human milk SOX is stable in an acid environment: 50% of its activity remains after 1 h at pH 2.5. Acid stability is also characteristic of gamma-glutamyltranspeptidase, another membrane-bound enzyme in skim milk. SOX is resistant to pepsin (4000 U/ml), trypsin (50 micrograms/ml), chymotrypsin (200 micrograms/ml), and to trypsin plus chymotrypsin (25 micrograms each/ml). Milk SOX activity has been detected in the stomach and proximal small intestine contents of suckling rats. Human and bovine SOX are relatively heat stable: 75% of the latter remains after treatment at 62.5 degrees C for 30 min and 65% of the former remains after treatment at 60 degrees C for 10 min. Neither remains after 62.5 degrees C for 30 min.

Animals↗
PubMed1982

Sulfur amino acid metabolism in the developing rhesus monkey brain: interrelationship of taurine and glutamate.

The relationship of taurine to glutamate, and to other amino acids, has been examined in the occipital lobe of the developing rhesus monkey. During development taurine decreases in concentration (4.96 mumol/g in fetus to 1.52 mumol/g in adult) while glutamate increases (7.92 mumol/g in fetus to 11.26 mumol/g in adult). When the concentration of taurine is plotted against that of glutamate in fetal, neonatal and adult animals there is a significant correlation in the fetal (p less than 0.01) and adult (p less than 0.01) but not in the neonatal occipital lobe samples. This correlation in both fetal and adult brain is specific for these amino acids. Subcellular fractionation studies further indicate that this relationship may be of special importance in nerve endings.

Aging↗