Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “GALACTOSE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed1996

Effects of seven days of galactose feeding and aldose reductase inhibition on mast cells and vessel morphometry in rat sciatic nerve.

The association between mast cells and vessel morphometry in sciatic nerve was examined after seven days in animals fed a diet of 40% D-galactose and compared to control rats and to galactose-fed animals treated with the aldose reductase inhibitor, Tolrestat. Electron microscopy revealed an increase in the total number of mast cells and the number of degranulated mast cells in galactose-fed animals (7.8 +/- 2.9; 2.6 +/- 2.9; mean +/- SD) compared to controls (4.6 +/- 2.1; degranulated mast cells were not seen in any control nerves) and Tolrestat-treated, galactose-fed animals (4.4 +/- 2.5; 0.1 +/- 0.4). Although no significant differences were noted in the numbers of vessels between the three groups, an index of vasoconstriction was significantly increased in the galactose-fed animals (0.115 +/- 0.048; mean +/- SD) compared to controls (0.068 +/- 0.011) and Tolrestat-treated, galactose-fed animals (0.075 +/- 0.20). These data suggest that mast cell degranulation is associated with the vascular constriction induced by seven days of galactose intoxication and that both may be prevented by inhibiting aldose reductase.

Aldehyde Reductase↗
PubMed1985

Spin labelling of sialic acid and galactose residues on lymphocyte plasma membrane: effects of lectins on oligosaccharide dynamics.

To investigate the behaviour of glycoprotein and glycolipid receptors at the lymphocyte cell surface, a spin label probe has been introduced into either sialic acid or galactose residues on lymphocyte plasma membrane, using specific activation of sugars with periodate or galactose oxidase, followed by reductive amination. The extent of membrane labelling could be controlled by varying the mole ratios of reactants used. Chloroform-methanol extraction of the labelled membranes showed that approximately 17% of the label is bound to glycolipids. A large fraction of the spin label could be released from both sialic acid and galactose-labelled membrane by treatment with pronase, indicating attachment to membrane proteins. Rotational correlation times (tau c) for both labelled sialic acid and galactose residues were in the range 10-13 X 10(-10) sec, indicating a reduction in sugar headgroup mobility at the membrane surface. Isolated lymphocyte membrane glycoproteins spin labelled on galactose residues and reassembled into phospholipid bilayer vesicles showed similar motional characteristics. Prolonged incubation of conc. suspensions of labelled membrane resulted in cleavage of the sialic acid-bound (but not the galactose-bound) label. Binding of several lectins to labelled plasma membrane produced significant immobilization of cell surface oligosaccharides while others had no effect. This differential restriction in oligosaccharide motion following lectin binding appears to be at least partly related to the sugar specificity of the lectin. Binding of wheat germ agglutinin and Ricinus communis agglutinin to sialic acid and galactose-labelled membrane respectively produced a dramatic decrease in oligosaccharide mobility which was reversible on addition of the appropriate sugar inhibitor. The concn dependence of lectin-induced spin label immobilization suggested a cooperative interaction between the lectins and their oligosaccharide receptors. Binding of lectins to the lymphocyte cell surface thus seems to have distinct effects on the dynamic state of glycoproteins and glycolipids within the glycocalyx.

Animals↗
PubMed1991

Galactose effects on enterocyte differentiation in the mouse jejunum.

The present work investigates the ability of galactose to affect enterocyte differentiation during normal development in vivo. Energy intake has also been varied to take account of the fact that galactose is poorly metabolized in mice. Brush-border lactase, alpha-glucosidase, dipeptidylpeptidase-IV, aminopeptidase N, alkaline phosphatase and microvillus length were measured as markers of enterocyte differentiation in mice fed diets containing galactose (G diet), corn oil (E diet) or galactose + corn oil (G + E diet). Maintaining mice on a G instead of E diet reduced brush-border lactase activity and enterocyte migration rates; alpha-glucosidase, dipeptidylpeptidase-IV, aminopeptidase N and microvillus length expression increased and alkaline phosphatase activity remained unchanged. Feeding the G + E diet restored enterocyte migration rates, lactase, aminopeptidase N and dipeptidylpeptidase-IV activities to values found in mice fed the E diet. Galactose stimulation of alpha-glucosidase and microvillus length expression was, however, fully maintained in mice fed the G + E diet. Present results show that enterocyte differentiation is affected independently by varying dietary galactose and energy levels; that galactose effects always increase and energy effects usually decrease expression of enterocyte components and that energy stimulation of lactase activity is exceptional.

Animals↗
PubMed1977

Galactose utilization by the rat tapeworm, Hymenolepis diminuta.

1. Hymenolepis diminuta incorporated label from 14C-galactose into glycogen, but the sugar would not support net glycogen synthesis. Glucose stimulated the incorporation of label from 14C-galactose into glycogen, while glycerol did not. 2. During incubations in galactose, large internal pools of galactose and galactose 1-P accumulated, while the concentration of glucose 6-phosphate remained unchanged. 3. In vitro culture experiments indicated that galactose would not support worm growth. Therefore, while galactose can be metabolized to a limited extent, it cannot substitute for glucose as a nutrient source.

Animals↗
PubMed1997

Brain inositol monophosphatase identified as a galactose 1-phosphatase.

During the course of our analysis of myo-inositol monophosphatase (IMPase), a key enzyme of brain inositol signaling, we found it also hydrolyzes galactose 1-phosphate (Gal 1-P), an intermediate of galactose metabolism. Electrophoretically homogeneous IMPase was prepared from three different sources: (i) bovine brain, (ii) rat brain, and (iii) human brain (recombinant), which demonstrated similar ability to hydrolyze inositol monophosphates and galactose 1-phosphate. The ability of IMPase to use both inositol 1-phosphates and galactose 1-phosphate equally as substrates is of considerable importance in determining lithium's mechanism of action. Our current results suggest that during lithium therapy, both galactose and inositol metabolic pathways can be simultaneously modulated through lithium inhibition of IMPase. Enzyme studies with Mg2+ ions as activators and with Li+, Ca2+, Mn2+, Ba2+ ions as inhibitors demonstrate that IMPase is a single enzyme possessing the ability to hydrolyze both inositol monophosphates and Gal-1-P with equal efficiency. In addition, gel-filtration chromatographic analysis demonstrated that IMPase and galactose 1-phosphatase activities co-purify in our electrophoretically homogeneous enzyme preparations. Our results indicate that lithium inhibition of IMPases at clinically relevant concentrations, may modulate both inositol and galactose metabolism, and identifies yet another carbohydrate pathway utilizing IMPase.

Amino Acid Sequence↗
PubMed1998

Nerve conduction velocity, laser Doppler flow, and axonal caliber in galactose and streptozotocin diabetes.

In an initial study, the effects of galactose intoxication on nerve laser Doppler blood flow (NLDF) and nerve conduction velocity (NCV) were assessed after 1-16 weeks of galactose feeding in pentobarbital-anesthetized rats. NLDF was not significantly changed at any time point. NCV was significantly reduced after 16, but not 1 or 4, weeks of galactose feeding. In a second study, NLDF was not significantly changed by 4 weeks of galactose intoxication, but streptozotocin-diabetic NLDF was significantly reduced compared to both control (P<0.001) and galactose-intoxicated rats (P<0.05). Compared to control animals, sciatic motor NCV was significantly (P<0.001) reduced in the galactose group, while sciatic and saphenous sensory NCVs were not significantly changed. In the streptozotocin-diabetic rats, motor and sensory NCVs were all significantly reduced (P<0.001). In contrast to the NCV findings, mean caliber of myelinated axons in both the saphenous and sciatic nerves was reduced in galactose-intoxicated, but not streptozotocin-diabetic rats. The observed sequence of changes associated with these two models of diabetic neuropathy is not consistent with the proposed roles of ischemia and axonal dwindling in the reported nerve conduction deficits.

Animals↗
PubMed1985

Perinatal galactose metabolism.

Galactose is a major nutrient in normal newborn infants and serves as a substrate for energy production and fuel storage and a regulator of carbohydrate assimilation. Inborn errors of galactose metabolism have contributed to our understanding of the potential toxicity of this carbohydrate. In addition to the classic acute manifestations of neonatal galactosemia, long-term follow-up of surviving patients have revealed unusual neurodevelopmental and reproductive problems. Many investigators have suggested that the newborn infant can utilize galactose better than adults and that neonatal galactose assimilation exceeds that of glucose. Galactose may be an excellent substitute for glucose among hyperinsulinemic infants of diabetic mothers or premature infants with glucose intolerance. However, until further investigations are performed to define the role of galactose in newborn nutrition and to determine its potential toxicity, galactose should not be used as the primary carbohydrate in sick newborn infants.

Cell Membrane Permeability↗
PubMed2003

Renal excretion of galactose and galactitol in patients with classical galactosaemia, obligate heterozygous parents and healthy subjects.

The age dependence of galactose and galactitol excretion was assessed in overnight-fasted galactose-1-phosphate uridyltransferase-deficient patients under dietary treatment (ages 4-34 years; n = 51), obligate heterozygous parents (ages 25-71 years; n = 49) and healthy subjects (ages 3-58 years; n = 215). Urine concentrations were analysed by stable-isotope dilution gas chromatography mass spectrometry. There was considerable interindividual variability. The intraindividual variation, however, was not age-dependent and was rather low. Excretion estimates were calculated from the creatinine-related concentrations using weight-, age- and sex-related creatinine excretion rates. Experimental evidence is presented underscoring the problems inherent in random sampling and substantiating the primary endogenous origin of galactose and galactitol in postabsorptive urine samples. Age-dependent excretion estimates were best fitted to a simple growth-related model assuming an exponential decrease with age until adulthood. According to the model, mean postabsorptive galactose and galactitol excretion in healthy subjects was similar and decreased exponentially from about 1.2 micromol/kg body weight per day in infants to about 0.2 micromol/kg body weight per day in adults. Excretion in heterozygotes was normal. In galactosaemic patients, galactose excretion was in the normal range. Galactitol excretion, however, was enhanced over 50-fold and decreased from a mean estimate of about 64 micromol/kg body weight per day in infants to about 23 micromol/kg body weight per day in adults. The results are discussed with respect to the significance of galactose and galactitol excretion for whole-body galactose removal and with respect to the applicability of urinary galactitol analysis for metabolic monitoring in galactosaemia.

Adolescent↗
PubMed2004

Biosensor based on Langmuir-Blodgett films of poly(3-hexyl thiophene) for detection of galactose in human blood.

An amperometric biosensor was developed to estimate galactose in human blood serum. Monolayers of poly(3-hexyl thiophene) were placed on glass plates coated with indium tin oxide formed by dispensing a mixed solution of stearic acid in chloroform on to a water sub-phase. Galactose oxidase was mixed with poly(3-hexyl thiophene)/stearic acid in chloroform and dispensed on to the air-water interface of Langmuir-Blodgett trough. These monolayers were transferred on to glass plates which were used as working electrodes with platinum as a reference electrode. The amperometric galactose biosensor thus fabricated had a linear response from 0.05 to 0.5 g galactose l(-1) in blood serum. The normal level in blood is < 0.05 g galactose l(-1) in adults and 0-0.2 g galactose l(-1) in infants. In case of galactosemia, this increases to above 0.2 g galactose l(-1) in infants.

Adult↗
PubMed1995

Time-dependent aspects of osmolyte changes in rat kidney, urine, blood and lens with sorbinil and galactose feeding.

Sorbitol plus myo-inositol, betaine and glycerophosphorylcholine (GPC) are cellular osmolytes in the mammalian renal medulla. Galactosemia and hyperglycemia can cause excessive levels of galactitol or sorbitol in several organs via aldose reductase (AR) catalysis. AR inhibitors can reduce these polyols. To examine osmolyte responses to polyol perturbations, male Wistar rats were fed normal diet, the AR inhibitor sorbinil (at 40 mg/kg/d), 25% galactose, or a combination, for 10, 21 and 42 days. All animals at 21 days had higher apparent renal AR activity than at 10 or 42 days, possibly providing resistance to sorbinil. Sorbinil feeding alone tended to increase urinary, plasma and renal urea levels. It reduced AR activity and sorbitol contents in renal inner medulla, though less so at 21 days; other renal osmolytes, especially betaine, were elevated. Galactose feeding caused little change in renal AR activity, and resulted in high galactose and galactitol contents in renal medulla, urine, blood and lens (and higher renal Na+ contents at 10 days). Renal sorbitol, inositol and GPC decreased, while betaine contents trended higher at all times. Sorbinilgalactose feeding reduced renal AR activities and galactitol contents (again less so at 21 days), urine, blood and lens galactitol, and further reduced renal sorbitol contents. At 10 and 21 days it tended to raise renal betaine more, and restore inositol (but not GPC) contents to control levels. At 42 days it reduced renal and urinary Na+ and galactose, and decreased renal betaine to control levels. Under most conditions, total renal (non-urea) organic osmolyte contents (presumed to be mostly intracellular) and Na+ plus galactose contents (presumed mostly extracellular) changed together such that cell volumes may have been maintained. The exception was 10 days on galactose, where total osmolytes appeared too low. In galactose-fed animals, urine/plasma ratios suggest some renal galactitol efflux, and cellular galactitol probably helps maintain osmotic balance rather than cause swelling.

Aldehyde Reductase↗
PubMed2002

Characterization of the promoter regions involved in galactose- and nisin-mediated induction of the nisA gene in Lactococcus lactis ATCC 11454.

The nisA promoter is positively regulated in Lactococcus lactis ATCC 11454 by autoinduction via a two-component NisRK-mediated system. However, induction of this promoter can also occur when introduced into the plasmid-free L. lactis LM0230 during growth in galactose or lactose, independent of the NisRK system. In this study, we also characterized this galactose-mediated induction by determining the nisA start site during growth in galactose, which was identical to the nisA start site upon nisin induction. The region involved in the galactose-mediated induction of the nisA promoter was investigated by directed deletion analysis of a 200 bp region upstream of the nisA promoter in the transcription fusion pDOC99. The induction of the deletion derivatives by galactose and nisin was compared phenotypically using beta-galactosidase measurements, and the regions necessary for the induction were determined by sequence analysis. Analysis of these regions revealed two sets of a TCT direct repeat [TCT-N8-TCT] present at positions (-107 to -94) and (-39 to -26) relative to the transcription initiation site. Disruption of the upstream repeat abolished galactose induction and significantly reduced the nisin induction capacity, suggesting a potential pivotal role for these repeats in transcription induction of the nisA promoter. It was also observed that the galactose-mediated induction was abolished when a plasmid containing the phosphotransferase system (PTS), phospho-beta-galactosidase and tagatose pathway genes was introduced into this strain. As this effectively made the Leloir pathway redundant, it points to some component of this pathway as the specific inducer of the nisA promoter.

Bacterial Proteins↗
PubMed2003

Galactose content of baby food meats: considerations for infants with galactosemia.

Treatment of galactosemia requires a galactose-restricted diet. Although meats are not traditionally thought of as a dietary carbohydrate source, small amounts may be present in free form and/or bound to proteins or lipids. The purpose of this study was to determine the free and bound galactose contents of baby food meats. Galactose was assayed using high-performance liquid chromatography. The free galactose content of baby food meats ranged from 0 to 0.031 mg/100 g. No statistically significant differences in free galactose content were found among the meats. Bound galactose was found in all analyzed baby food meats, ranging from 0.065 to 0.148 mg/100 g. The mean galactose content of BeechNut chicken (St. Louis, MO) was significantly less than that found in Gerber (Fremont, MI) and Heinz (Pittsburgh, PA) brands of chicken, beef, and turkey, and Gerber lamb and veal. Based on current recommendations, all examined baby food meats would be acceptable for infants with galactosemia.

Animals↗
PubMed1997

Galactose-dependent reversible interaction of Gal3p with Gal80p in the induction pathway of Gal4p-activated genes of Saccharomyces cerevisiae.

When galactose is added to logarithmically growing culture of the yeast Saccharomyces cerevisiae, a set of genes encoding galactose-metabolizing enzymes (GAL genes) starts to be transcribed within a few minutes. This rapid induction involves a serial interplay of Gal3p, Gal80p, and Gal4p. Recent experiments have indicated that a direct interaction between Gal3p and Gal80p plays a pivotal role in an early step of GAL induction. Here we demonstrate that complex of Gal3p and Gal80p, otherwise unstable, is stabilized in the presence of 0.1 mM galactose and 0.5 mM ATP. The requirement for galactose and ATP for stable complex formation is also observed by using highly purified Gal3p and Gal80p from yeast. We further show that thus formed Gal3p/Gal80p complex can easily be dissociated when it is washed with buffer lacking galactose. Finally, we show that mutant proteins encoded by GAL80S or GAL80DE21, which confer galactose-uninducible phenotype, fail to interact with Gal3p. These results strongly suggest that Gal3p functions as the sensor and transducer of galactose signal in the induction pathway of Gal4p-activated genes.

Adenosine Triphosphate↗
PubMed1997

Amino acid residues responsible for galactose recognition in yeast Gal2 transporter.

A novel, systematic approach was used to identify amino acid residues responsible for substrate recognition in the transmembrane 10 region of the Gal2 galactose transporter of Saccharomyces cerevisiae. A mixture of approximately 25,000 distinct plasmids that encode all the combinations of 12 amino acids in transmembrane 10 that are different in Gal2 and the homologous glucose transporter Hxt2 was synthesized. Selection of galactose transport-positive clones on galactose limited agar plates yielded 19 clones, all of which contained the Tyr446 residue found in Gal2. 14 of the 19 clones contained Trp455 found in Gal2, whereas the other 5 contained Cys455, a residue not found in either Gal2 or Hxt2. When Tyr446 of Gal2 was replaced with any of the other 19 amino acids, no galactose transport activity was observed in the resulting transporters, indicating that Tyr446 plays an essential role in the transport of this sugar. Replacement of 2 amino acids of Hxt2 with the corresponding Tyr446 and Trp455 of Gal2 allowed the modified Hxt2 to transport galactose. The Km of galactose transport for the modified transporter was 8-fold higher than that of Gal2. These results and other evidence unequivocally show that Tyr446 is essential and Trp455 is important for the discrimination of galactose versus glucose.

Amino Acid Sequence↗
PubMed2006

13C-methacetin and 13C-galactose breath tests can assess restricted liver function even in early stages of primary biliary cirrhosis.

OBJECTIVE: The 13C-methacetin breath test quantitatively evaluates cytochrome P450-dependent liver function. The 13C-galactose breath test non-invasively measures the galactose oxidation capacity of the liver. The aim of this study was to find out whether these breath tests are sensitive parameters also in non-cirrhotic patients with primary biliary cirrhosis. MATERIAL AND METHODS: Nineteen patients with early-stage primary biliary cirrhosis (no cirrhotic alterations in the liver biopsy, Ludwig stage I-III) and 20 healthy controls underwent the 13C-methacetin and 13C-galactose breath tests. RESULTS: Patients with primary biliary cirrhosis metabolized less 13C-methacetin than controls (cumulative recovery within 30 min 7.5+/-2.4% versus 14.0+/-2.6%; p < 0.001). When a cut-off > 9.8% was used for the cumulative recovery after 30 min, the methacetin breath test reached 84.2% sensitivity and 95.0 specificity. In the 13C-galactose breath test, the percentage recovery at 60 min in patients was 3.1+/-1.3%/h, and 6.3+/-1.1%/h in controls (p < 0.001). Using a cut-off > 4.7%/h, the galactose breath test reached 89.5% sensitivity and 95.0 specificity. CONCLUSIONS: In non-cirrhotic, early-stage, primary biliary cirrhosis the 13C-methacetin breath test and the 13C-galactose breath test reliably indicate decreased liver function. The 13C-galactose breath test can also predict the histological score.

Acetamides↗
PubMed1967

High-resolution radioautography of galactose-3H accumulation in rings of hamster intestine.

Radioautography of water-soluble substances has posed a major technical problem for the past decade. Utilizing silicone-impregnated plastic sections of frozen-dried tissue, a quantitative method was developed for studying distribution of (3)H-labeled galactose, mannitol, and phlorizin. The content of a 2-micro band may be measured with an accuracy of +/-20% by light microscopy; radioautographs may also be prepared for the electron microscope. Results with intestinal tissue incubated 1-10 min in vitro and, then, frozen rapidly indicate that the first step in galactose absorption is uphill transport into the brush border of the columnar epithelium. Correction of galactose content for the mannitol space in the brush border suggests that the sugar pump is located at the surface of the microvilli. Further evidence for the surface locus of the glucose-galactose pump was obtained with phlorizin (next paper, reference 40). The galactose content of columnar cell cytoplasm always equalled that of microvilli and no transcellular diffusion gradient could be detected; during the first minutes of incubation, however, a gradient did exist between nucleoplasm and cytoplasm. Downhill exit of galactose from columnar cells may have proceeded either directly across basal membranes to adjacent lamina propria or indirectly via open intercellular spaces. Lastly, even in the absence of muscularis, the connective tissue of the lamina propria constituted enough of a diffusion barrier so that it served as a secondary accumulating compartment for galactose under present in vitro conditions.

Animals↗
PubMed1993

Aldose reductase inhibitors and galactose toxicity in neonatal and maternal rat lenses.

We reported that in utero galactose-induced cataracts could be inhibited if aldose reductase inhibitors (ARIs) were included in the galactose diet of pregnant rats. These studies involved morphological and cytochemical approaches. We undertook this investigation to evaluate the effects of ARIs in preventing the formation, accumulation and depletion of dulcitol in lenses of in utero galactose exposed neonates and in mothers during and following pregnancy. Sprague Dawley rats were fed Purina Rat Chow with 50% galactose either with or without 15mg Sorbinil or 1mg Eisai compound E-0722/day/Kg body weight during and following pregnancy. The lenses of neonates and mothers were processed to determine dulcitol concentrations. At parturition there was a significant amount of dulcitol in the lenses of pups and their mothers, which reduced rapidly in the lenses of pups regardless of the diet fed to the nursing mother. While galactose had a cross-placental but not a milk-mediated effect, the ARIs had both cross-placental and milk-mediated effects on dulcitol accumulation and depletion, respectively. The galactose feeding of mothers post-parturition maintained the high lenticular dulcitol concentration and the absence of galactose led to a reduction in lenticular dulcitol. The correlation between dulcitol accumulation and cataract development is discussed.

Aldehyde Reductase↗
PubMed1997

Preventive action of vitamin E-containing liposomes on cataractogenesis in young adult rats fed a 25% galactose diet.

The preventive action of vitamin E (Vit. E)-containing liposomes on cataractogenesis was examined in male Wistar rats (five weeks old) fed a 25% galactose diet. Vit. E-containing liposomes prepared with dipalmitoylphosphatidylcholine were instilled into both eyes three times a day over a 45-day period. Cataract appeared at 18-day galactose feeding and developed gradually thereafter. Simultaneous Vit. E-containing liposome instillation delayed this cataractogenesis. Lenses of 18-day galactose-fed rats showed decreases in Vit. E and reduced glutathione (GSH) contents and Na+, K(+)-ATPase activity and increases in lipid peroxide (LPO), galactitol, and water contents. Lenses of 45-day galactose fed rats showed decreases in GSH content and Na+,K(+)-ATPase activity and increases in Vit. E, LPO, galactitol, and water contents. Serum Vit. E and cholesterol levels decreased in 18-day galactose-fed rats, while both levels increased in 45-day galactose-fed rats. Simultaneous Vit. E-containing liposome instillation prevented these changes except for the changes of lenticular galactitol and water contents and serum Vit. E and cholesterol levels. These results indicate that simultaneously instilled Vit. E-containing liposomes can delay cataractogenesis in young adult rats fed a 25% galactose diet mainly by the antioxidative action of Vit. E contained in the instilled liposomes.

Animals↗