Galactose metabolism and its regulation

Cohn, Roy; Segal, Stanton

doi:10.1016/0026-0495(73)90078-4

Cited by 61 publications

(35 citation statements)

References 69 publications

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“…It is a major energy source in almost all mammals in the suckling period (8). In infants feeding 462 SHIMONO on milk, the galactose content in the blood comprises about 40 per cent of the blood sugar (18).…”

Section: Distributionmentioning

confidence: 99%

“…During this time, the urine also had high radioactivity comparable to that of the kidney, indicating a rapid excretion of the injected galactose into the urine. Some investigators reported that less than 10% of the galactose injected intravenously in human was excreted in the urine (8,9,43,51) . But Starling et al (47) reported that three hr after intraperitoneal injection of 2-deoxy-D-[l-14C]galactose in rats, 51 % was excreted with the urine.…”

Section: R-mentioning

confidence: 99%

“…Another similarity between the labeled galactose and glucose, as stated above, was shown in the incorporation pattern of radioactivity into the acid-insoluble substances of mucous salivary glands. This suggests that a considerable amount of labeled galactose is taken up into these glands after having been converted to glucose in certain other organs such as the liver and kidney where the conversion of galactose into glucose is active through the Leloir pathway (8,9,41,43) . This speculation is supported by the facts that the Harderian gland utilizes considerable amount of glucose in synthesizing lipids via hexose monophosphate shunt (24,56).…”

Section: R-mentioning

confidence: 99%

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Whole-body autoradiographic study on the distribution of (U-14C)galactose in adult, pregnant, newborn and infant mice.

Shimono

1984

Acta Histochem. Cytochem

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Section: Distributionmentioning

confidence: 99%

Section: R-mentioning

confidence: 99%

Section: R-mentioning

confidence: 99%

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Whole-body autoradiographic study on the distribution of (U-14C)galactose in adult, pregnant, newborn and infant mice.

Shimono

1984

Acta Histochem. Cytochem

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“…By the Leloir pathway, galactose was predominantly metabolized in the liver, where the enzymes had high activity (3,8,12,33). Galactose could be converted into glycogen or released as glucose, pyruvate and lactate (6,26). Because of the high radioactivity for origin or RG 0.28, it is assumed that in the liver these metabolites may be present in the glycogen or glucose form.…”

Section: Discussionmentioning

confidence: 99%

“…According to Bassett et al (2), no galactose remained in the blood at 75 min after the injection of galactose in normal adults. Cohn et al (6) found that after an intravenous injection of radioactive galactose to normal adults, 50% of the radioactivity was found in the body glucose pools within 30 min. These findings may be in good agreement with our present results.…”

Section: Discussionmentioning

confidence: 99%

Whole-body autoradiographic study of (U-14C) galactose in mice and its biochemical analysis.

Shimono

1985

Acta Histochem. Cytochem

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Tissue and organ distribution and metabolic fate of radioactive carbon from [U-14C] galactose in mice were studied by whole-body autoradiography and biochemical analysis.Autoradiography was performed before and after 6 % perchloric acid treatment at various intervals after intravenous injection of [U-14C] galactose. At 5 min after injection, high radioactivities were observed in the kidney, small intestine and liver.The radioactivities in almost all organs were markedly decreased with the acid treatment.At 30 min after injection, the kidney and small intestine had relatively high radioactivities which were retained by the acid treatment.As for the biochemical analysis, at various intervals after intravenous injection of [U-14C] galactose, the mice were decapitated, and the blood, liver, kidney, small and large intestines, myocardium and brain were removed. These organs were fractionized into 6 % perchloric acid-soluble, -insoluble and lipid parts.Total radioactivity (cpm) per gram of wet weight was the highest in the kidney.The incorporation rates of the radioactivity into the acid-soluble fraction were high in all organs at early intervals, while at late intervals, the rates into the acid-insoluble fraction became relatively high in the kidney, small and large intestines.These results were consistent with those obtained from whole-body autoradiography.Acid-soluble fractions of the blood, kidney, liver and brain were analyzed by paper chromatography.The radioactive spots for galactose and glucose were observed in all organs examined, but the changes of radioactive values with the passage of time were different in each organ.Furthermore, the radioactive spots for RGlucose value 0.28 were detected in these organs.Galactose is C-4 epimer of glucose and is derived from lactose. Ingested lactose is absorbed in the small intestine and then hydrolyzed by 3-galactosidase (lactase) into glucose and galactose. It is generally accepted that galactose is conveyed to the liver, where it is converted to glucose by the Leloir pathway (18). In the previous studies, enzyme activities belonging to this pathway have been found in the liver (3, 5, 8, 33), kidney (3, 5, 8, 16, 20, 25, 34), intestine (23), brain (21,32,40) and myocardium (21) etc. On the other hand, it has been reported that galactose is an important constituent of the glycoproteins, glycolipids and mucopolysaccharides (1,4,10,13,14,15,22).

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Galactose and glucose metabolism in galactokinase deficient, galactose‐1‐P‐uridyl transferase deficient and normal human fibroblasts

Friedman¹,

Yarkin²,

Merril³

1975

Journal Cellular Physiology

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Despite the genetic interruption of the Leloir pathway both galactosemic patients and galactosemic fibroblasts can convert galactose to CO2 and TCA precipitable products, although at less than the normal rate. These observations stimulated investigations into the identity of the alternative metabolic routes which allows for galactose metabolism in the absence of in vitro galactose-1-P-uridyl transferase. Four lines of galactosemic cells, each without detectable gal-transferase, produced 14CO2 from [1-14C]-galactose (0.094 mumoles in 20 cc of medium) at approximately 39% +/- 16% the rate of transferase positive cells over a 48-hour period. However, galactokinase deficient fibroblasts produced 14CO2 and TCA precipitable products from [1-14C]-galactose or [U-14C]-galactose at only 3% to 9% the rate of normal fibroblasts. Therefore it seems likely that gal-transferase deficient fibroblasts must first synthesize galactose-1-P for further metabolism of galactose.

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Galactose metabolism and its regulation

Cited by 61 publications

References 69 publications

Whole-body autoradiographic study on the distribution of (U-14C)galactose in adult, pregnant, newborn and infant mice.

Whole-body autoradiographic study on the distribution of (U-14C)galactose in adult, pregnant, newborn and infant mice.

Whole-body autoradiographic study of (U-14C) galactose in mice and its biochemical analysis.

Galactose and glucose metabolism in galactokinase deficient, galactose‐1‐P‐uridyl transferase deficient and normal human fibroblasts

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