Biomedical subjects

A Jones

Publications and source records attributed to A Jones.

At least 667 records · Page 37Linked to original sources

PubMed1973

Mineral content of brands of milk for infant feeding.

The amounts of sodium, potassium, phosphorus, and nitrogen in several brands of milk used for infant feeding have been measured, and the concentrations of these substances in the reconstituted milks calculated. The known variation in the electrolyte content of cows' milk and the addition of minerals in the manufacture of many types of milk foods may account for the variation in the content of these substances, but the addition of neutralized whey in the manufacture of Trufood Formula 4 increased the concentration of sodium to a level twice that found in undiluted cows' milk. We think that details of all mineral additions to milks used for infant feeding should be made readily available and that the mineral content of the powders or liquids should be printed on the containers and expressed both in mg/100 g and mEq/kg. Milks reconstituted to a composition close to that of cows' milk present large osmotic loads to the kidneys, and may endanger water balance in some circumstances. This risk can be reduced by a greater dilution with water.

Animals↗

PubMed1973

Microbial metabolism of amino alcohols. 1-Aminopropan-2-ol and ethanolamine metabolism via propionaldehyde and acetaldehyde in a species of Pseudomonas.

1. Growth and manometric experiments showed that a Pseudomonas sp. P6 (N.C.I.B. 10431), formerly known as Achromobacter sp. P6, was capable of growth on both stereoisomers of 1-aminopropan-2-ol, and supported the hypothesis that assimilation involved metabolism to propionaldehyde, propionate and possibly 2-hydroxyglutarate. A number of alternative intermediary metabolites were ruled out. 2. Accumulation of propionaldehyde from 1-aminopropan-2-ol by intact cells occurred only during active growth, was transitory and was accompanied by morphological changes in the pseudomonad. 3. Enzymic and radioactive tracer evidence showed that 1-aminopropan-2-ol O-phosphate was the intermediate between amino alcohol and aldehyde. The operation of an inducibly formed ATP-amino alcohol phosphotransferase was established by measuring substrate disappearance, ADP formation and amino alcohol O-phosphate formation. This novel kinase had two activity peaks at about pH7 and 9. It acted on both l- and d-isomers of 1-aminopropan-2-ol, and also on l-threonine and ethanolamine, but had only low activity towards choline. The enzyme was partially purified by ion-exchange chromatography. 4. An amino alcohol O-phosphate phospho-lyase (deaminating) produced propionaldehyde from dl- and d-1-aminopropan-2-ol O-phosphate, and also formed acetaldehyde less rapidly from ethanolamine O-phosphate. It had optimum activity at about pH8 in Tris-HCl buffers. The enzyme was partially purified and evidence was obtained that a single enzyme was responsible for both activities. Apparent K(m) values for the substrates were determined. Activity was inhibited by dl-threonine O-phosphate, dl-serine O-phosphate, choline O-phosphate and P(i). Enzyme formation was induced by growth with either amino alcohol substrate. 5. Radioactive tracer experiments with dl-1-amino[3-(14)C]propan-2-ol confirmed the operation of the amino alcohol kinase and demonstrated coupling with the phospho-lyase enzyme in vitro to produce [(14)C]-propionaldehyde. 6. An aldehyde dehydrogenase, found in extracts of the pseudomonad after growth on 1-aminopropan-2-ol, was characterized and concluded to be responsible for propionaldehyde and acetaldehyde oxidation. The enzyme was inactive with methylglyoxal. 7. Propionate and acetate were concluded to be metabolized via propionyl-CoA and acetyl-CoA, and studies were made of a CoA ester synthase found in extracts. 8. Studies of a strain of Pseudomonas putida N.C.I.B. 10558 suggested that 1-aminopropan-2-ols were metabolized via their O-phosphates, propionaldehyde and propionate. Amino alcohol kinase activity was detected and extracts contained a phospho-lyase showing higher activity with the 1-aminopropan-2-ol O-phosphate than with ethanolamine O-phosphate.

1-Propanol↗

PubMed1973

Microbial metabolism of amino alcohols. Metabolism of ethanolamine and 1-aminopropan-2-ol in species of Erwinia and the roles of amino alcohol kinase and amino alcohol o-phosphate phospho-lyase in aldehyde formation.

1. Growth of Erwinia carotovora N.C.P.P.B. 1280 on media containing 1-aminopropan-2-ol compounds or ethanolamine as the sole N source resulted in the excretion of propionaldehyde or acetaldehyde respectively. The inclusion of (NH(4))(2)SO(4) in media prevented aldehyde formation. 2. Growth, microrespirometric and enzymic evidence implicated amino alcohol O-phosphates as aldehyde precursors. An inducibly formed ATP-amino alcohol phosphotransferase was partially purified and found to be markedly stimulated by ADP, unaffected by NH(4) (+) ions and more active with ethanolamine than with 1-aminopropan-2-ol compounds. Amino alcohol O-phosphates were deaminated by an inducible phospho-lyase to give the corresponding aldehydes. This enzyme, separated from the kinase during purification, was more active with ethanolamine O-phosphate than with 1-aminopropan-2-ol O-phosphates. Activity of the phospho-lyase was unaffected by a number of possible effectors, including NH(4) (+) ions, but its formation was repressed by the addition of (NH(4))(2)SO(4) to growth media. 3. E. carotovora was unable to grow with ethanolamine or 1-aminopropan-2-ol compounds as sources of C, the production of aldehydes during utilization as N sources being attributable to the inability of the microbe to synthesize aldehyde dehydrogenase. 4. Of seven additional strains of Erwinia examined similar results were obtained only with Erwinia ananas (N.C.P.P.B. 441) and Erwinia milletiae (N.C.P.P.B. 955).

Acetaldehyde↗

PubMed1973