Nucleotide sugars: determination of cellular levels and discrepancies in results.
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Galactosemias↗
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Hidden sources of galactose in the environment.
A galactose-restricted diet free of lactose is lifesaving in patients with galactose-1-phosphate uridyl transferase (GALT) deficiency, but does not prevent long-term complications such as developmental delay, abnormal speech, poor growth and, in females, ovarian failure. Lactose, found in dairy products and as an extender in drugs, has been considered the primary source of galactose in the diet. Two recent publications reported that small amounts of galactose are present in many fruits and vegetables. We report the presence of considerable amounts of free galactose in some legumes (dried beans and peas) and the presence of bound galactose in many food plants. Galactose, in various glycosidic linkages, such as alpha-1,6, beta-1,3 and beta-1,4, and as a component of lipids, is ubiquitous in animals and plants. The bioavailability of alpha-1,6 and beta-1,3 linked galactose in foods is unknown. However, alpha-galactosidases found in plant and animal tissues may release galactose in alpha-1,6 linkage, and from diagalactosyldiacylglycerol. Galactose in beta-1,4 linkage and as monogalactosyldiacylglycerol may be released by beta-galactosidases in animal and plant tissues. Foods fermented by microorganisms for preparation or preservation purposes may contain free galactose. The role of free and bound galactose in cereals, fruits, legumes, nuts, organ meats, seeds, and vegetables in the poor outcome seen in some patients with GALT deficiency is unknown. It is certain that no patients with GALT deficiency have ever ingested a galactose-free diet.
Carbohydrate Sequence↗
Lactase deficiency in Nigerians.
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Adolescent↗
Adenosine triphosphatase in nerves and ganglia of rats with streptozotocin-induced diabetes or galactosaemia; effects of aldose reductase inhibition.
This study measured the ouabain-sensitive and ouabain-resistant adenosine triphosphatase activity in homogenates of the sciatic nerves and of pooled fourth and fifth lumbar dorsal root ganglia from rats fed 20% galactose or made diabetic with streptozotocin for either 4 or 8 weeks. Diabetes caused reductions in both fractions of sciatic nerve adenosine triphosphatase activity. After 8 weeks the ouabain-sensitive fraction was 54% of control (p less than 0.05) and the ouabain-resistant fraction was 57% of control (p less than 0.05). Galactose feeding more than doubled the ouabain-sensitive adenosine triphosphatase activity in the sciatic nerve (225% of control after 4 weeks, 215% of control after 8 weeks of galactose feeding, both p less than 0.01) and produced a progressive increase in the ouabain-resistant fraction (119% of control at 4 weeks (p less than 0.05) and 176% of control at 8 weeks (p less than 0.01)). In a group of rats fed galactose for 5 days, sciatic nerve ouabain-sensitive adenosine triphosphatase activity was 165% of control. Treatment with the aldose-reductase inhibitors tolrestat, ponalrestat or sorbinil prevented accumulation of polyol and depletion of myo-inositol in the sciatic nerves, indicating effective inhibition of aldose reductase. These drugs prevented completely the effect of galactose on the sciatic nerve adenosine triphosphatase activity, but had no significant effect on the reduction in adenosine triphosphatase activity in the sciatic nerves of diabetic rats. In the dorsal root ganglia galactose feeding had no measurable effect on the adenosine triphosphatase activity. Diabetes caused a modest numerical reduction in the ouabain-sensitive activity only.(ABSTRACT TRUNCATED AT 250 WORDS)
Adenosine Triphosphatases↗
Further observations in a case of uridine diphosphate galactose-4-epimerase deficiency with a severe clinical presentation.
The red-cell concentrations of galactose-1-phosphate and uridine diphosphate galactose have been studied in relation to dietary galactose in a case of uridine diphosphate galactose-4-epimerase deficiency (McKusick 23035). Uridine diphosphate galactose accumulates rapidly in response to very small amounts of galactose but the concentration of galactose-1-phosphate increases proportionately to galactose intake. The significance of the observation is discussed with respect to the pathogenesis and treatment of the disease.
Biotransformation↗
Mutations in the galactose-1-phosphate uridyltransferase gene of two families with mild galactosaemia variants.
Classical galactosaemia, deficiency of galactose-1-phosphate uridyltransferase (GALT), is characterized by acute symptoms of hepatomegaly, jaundice, sepsis, cataracts and growth retardation. Treatment with dietary galactose restriction corrects these complications immediately; however, most of these children develop long-term complications of verbal dyspraxia, mental retardation and ovarian failure. Our previous molecular study showed that the most common mutation of the GALT gene is a missense mutation of Q188R (replacement of glutamine-188 by arginine) in approximately 60-65% of the German galactosaemic population. The coding region of GALT was amplified by the polymerase chain reaction from genomic DNA of classical galactosaemic individuals, who are negative or heterozygous for Q188R, and was further characterized by direct sequencing. Three new disease-causing mutations, two missense and a stop codon mutation, were identified in three patients from two families with mild galactosaemic variants: firstly R67C, replacement of arginine-67 by cysteine and W316X, the stop codon at tryptophan-316 in one male; secondly A330V, replacement of alanine-330 by valine in two female siblings. In the first family the patient was also heterozygous for the polymorphism N314D and in the second family both girls were compound heterozygotes for Q188R and A330V. All three galactosaemic individuals have a considerable amount of the residual GALT activity in RBC and the galactose-1-phosphate (GALP) level decreased much faster on treatment than that of other galactosaemic patients with missense mutations such as Q188R. The clinical and biochemical data of these patients were much more favourable in comparison with those of two female galactosaemic individuals, one homozygous for L195P and the other compound heterozygous for Q188R and L195P. These three missense mutations (R67C, L195P and A330V) also occur in highly conserved regions. These observations suggest that the phenotypic variation in galactosaemic individuals may be due to different molecular aetiologies.
Adolescent↗
Observations on galactosaemic families.
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Galactosemias↗
Consequences of recurrent phosphate trapping induced by repeated injections of 2-deoxy-D-galactose. Biochemical and morphological studies in rats.
2-Deoxy-D-galactose, in a dose of 3 mmol/kg, was administered intraperitoneally twice daily to young rats for periods up to 12 weeks. This dosage schedule resulted in recurrent phosphate trapping predominantly in liver. UTP deficiency was excluded by simultaneous uridine injections. Phosphate trapping was caused by the rapid accumulation of 2-deoxy-D-galactose 1-phosphate and was most pronounced in liver but also demonstrated in small intestine, brain, spleen, and thymus. The marked, although transient, drop in the hepatic content of inorganic phosphate triggered the catabolism of adenine nucleotides and a loss of ATP. Other metabolic pathways affected by phosphate deficiency include glycogenolysis and glycolysis. Increasing with time, repeated doses of the galactose analog led to retardation and arrest of growth, hepatomegaly, and splenomegaly. The average relative liver and spleen weights were elevated 2.5- and 4.5-fold, respectively, after 12 weeks of treatment. Liver damage was indicated by hyperbilirubinaemia and a progressive rise in the activity in plasma of sorbitol dehydrogenase, alkaline phosphatase, and gamma-glutamyltransferase. Examination by light and electron microscopy showed increasing numbers of vacuoles, surrounded by a single membrane, in hepatocytes, sinusoidal endothelial cells, and Kupffer cells. Focal cytoplasmic degeneration in hepatocytes was occasionally indicated by formation of autophagic vacuoles and finger print lysosomes. Hepatocytes of 2-deoxy-D-galactose-treated rats showed a dissociation and fragmentation of the rough endoplasmic reticulum. Sinusoidal endothelial cells and Kupffer cells were markedly enlarged, the latter contained a PAS-positive but amylase resistant substance. Extrahepatic changes included an increased occurrence of vacuolated cells in thymus. Phosphate trapping and its metabolic consequences are common phenomena in the experimental injury induced b 2-deoxy-D-galactose and in some hereditary diseases such as uridylyltransferase deficiency galactosaemia, fructose intolerance and glucose-6-phosphatase deficiency.
Animals↗
Lens hexitols and cataract formation during lactation in a woman heterozygote for galactosaemia.
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Adult↗
Galactose metabolites in blood from neonates with and without hypergalactosaemia detected by mass screening.
UNLABELLED: Concentrations of galactose (Gal) in plasma and galactose metabolites in red blood cells (RBC) were determined in 18 normal neonates and 249 others with hypergalactosaemia according to the Paigen method. Normal neonatal values for plasma Gal, RBC galactose-1-phosphate (Gal-1-P), RBC uridine diphosphate glucose (UDP-Glc), and RBC uridine diphosphate galactose (UDP-Gal) were 0.96 +/- 0.71 mg/dl, 1.69 +/- 1.45 mg/dl of packed RBC, 1.00 +/- 0.45 mg/dl of packed RBC, and 1.44 +/- 0.45 mg/dl of packed RBC, respectively. The UDP-Gal concentration was higher and the UDP-Glc concentration lower than previously reported in normal children. Of the 249 cases with excessive Gal in whole blood, 23 showed high Gal concentrations in plasma; among these, four portacaval shunts and one case of congenital biliary atresia were diagnosed. In subjects homozygous or heterozygous for UDP-Gal-4 epimerase deficiency, concentrations of UDP-Gal and Gal-1-P were elevated only in RBC, corresponding to restriction of the metabolic abnormality to these cells. Most cases of hypergalactosaemia detected by the Paigen method have large excesses of Gal-1-P in RBC. Although a specific diagnosis based solely on blood Gal metabolites is difficult, individual concentrations reflect underlying conditions to some extent. CONCLUSION: In neonates, uridine diphosphate galactose concentrations were higher and uridine diphosphate glucose concentrations were lower than previously reported paediatric values. Patients with high plasma galactose concentrations should be investigated by hepatic imaging.
Biliary Atresia↗
Galactosaemia and allelic variation at the galactose-1-phosphate uridyltransferase gene: a complex relationship between genotype and phenotype.
UNLABELLED: More than 160 different base changes have been described at the galactose-1-phosphate uridyltransferase gene and most of these are associated with a disease phenotype. Q188R is the most common mutation in north European populations and those predominantly of European descent. K285N is much rarer but in some countries of east/central Europe it is the second most common mutation. In some populations of northern Europe these two mutations can be found on 70%-80% of mutant chromosomes. Both mutations appear to be associated with a complete loss in enzyme activity and thus, a more severe biochemical phenotype. A single amino acid substitution, N314D, is found on both Duarte 1 and Duarte 2 alleles. Additional base changes that are different on each distinguish D1 from D2 alleles. Whether the differences in galactose-1-phosphate uridyltransferase enzyme activities are associated with the additional molecular changes that distinguish D1 and D2 alleles remains unclear. S135L is found almost exclusively in galactosaemic individuals of African origin. Despite early diagnosis and treatment and adherence to a lactose free diet neurological complications, poor growth and reduced fertility are frequently observed in affected individuals. CONCLUSION: Allelic variation at the galactose-1-phosphate uridyltransferase gene undoubtedly plays a role in defining the biochemical and clinical phenotype. However, clinical galactosaemia is a complex trait in which multiple developmental and metabolic pathways are involved. Ultimately the phenotype is beyond the control of the single gene itself.
Allelic Imbalance↗
Gene expression profiling of diabetic and galactosaemic cataractous rat lens by microarray analysis.
AIMS/HYPOTHESIS: Osmotic and oxidative stress is associated with the progression and advancement of diabetic cataract. In the present study, we used a cDNA microarray method to analyse gene expression patterns in streptozotocin-induced diabetic rats and galactose-fed cataractous lenses. In addition, we investigated the regulation and interaction(s) of anti-oxidant protein 2 and lens epithelium-derived growth factor in these models. METHODS: To identify differential gene expression patterns, one group of Sprague-Dawley rats was made diabetic with streptozotocin and a second group was made galactosaemic. Total RNA was extracted from the lenses of both groups and their controls. Labelled cDNA was hybridised to Atlas Rat Arrays. Changes in gene expression level were analysed. Real-time PCR and western analysis were used to validate the microarray results. RESULTS: The expression of 31 genes was significantly modulated in hyperglycaemic lenses compared with galactosaemic lenses. Notably, transcript and protein levels of B-cell leukaemia/lymphoma protein 2 and nuclear factor-kappaB were significantly elevated in rat lenses at 4 weeks after injection of streptozotocin. At a later stage, mRNA and protein levels of TGF-beta were elevated. However, levels of mRNA for IGF-1, lens epithelium-derived growth factor and anti-oxidant protein 2 were diminished in streptozotocin-induced diabetic cataract. CONCLUSIONS/INTERPRETATIONS: These results provide evidence that progression of sugar cataract involves oxidative- and TGF-beta-mediated signalling. These pathways may promote abnormal gene expression in the hyperglycaemic and galactosaemic states and thus may contribute to the symptoms associated with these conditions. Since oxidative stress seems to be a major event in cataract formation, supply of anti-oxidant may postpone the progression of such disorders.
Animals↗
Nerve conduction and aldose reductase inhibition during 5 years of diabetes or galactosaemia in dogs.
To evaluate the role of excessive polyol pathway activity in the pathogenesis of nerve disorders in diabetes mellitus, nerve conduction velocity was measured in motor nerves of diabetic dogs given an aldose reductase inhibitor (Sorbinil) or placebo, and also in non-diabetic dogs made experimentally galactosaemic. The nerve conduction velocity slowly declined in the diabetic placebo group, becoming significantly less than normal by the fifth year of the study, and the decline was prevented by administration of the aldose reductase inhibitor. Non-diabetic dogs made galactosaemic by consuming a 30% galactose diet developed erythrocyte and nerve polyol concentrations many times greater than that of diabetic or normal animals, but the nerve conduction velocity remained normal throughout 5 years of study. These results in dogs suggest that aldose reductase inhibitors may prevent defective nerve conduction in long-term diabetes, and raise the possibility that excessive accumulation of polyol itself is not sufficient to produce the nerve defect in the absence of excessive polyol utilization.
Aldehyde Reductase↗
High-intensity basal ganglia lesions on T1-weighted images in two toddlers with elevated blood manganese with portosystemic shunts.
We report two toddlers with portosystemic shunts who had symmetrical high-signal globus pallidus lesions on T1- but not T2-weighted MRI, and measurement of whole blood manganese at 2 years of age. These cases suggest that portosystemic shunts can cause elevation of blood manganese and result in manganese accumulation in the globus pallidus, causing high signal on T1-weighted images even in asymptomatic toddlers.
Brain Diseases↗
Localization of protein kinase C in normal and galactosemic bovine lens epithelial cells in culture.
The localization of the two major isoforms of protein kinase C (PKC), PKCalpha and PKCgamma, present in normal and galactosemic bovine lens epithelial cells in culture, was determined using PKC isoform-specific antisera and visualized with FITC-conjugated secondary antisera. The results indicated that the localization of PKC changed upon exposure to 40 mM galactose after 1 day. The subcellular distribution of control cells was cytoplasmic and perinuclear for PKCalpha, while, in 40 mM galactose-treated cells, PKCalpha was also localized to nuclei. In contrast, upon exposure to 40 mM galactose the PKCgamma of the lens epithelial cells was observed in nucleoli. These results suggest that the subcellular distribution of the PKC isoforms in bovine lens epithelial cells differs and is altered upon exposure to 40 mM galactose.
Animals↗
Early diagnosis of inherited metabolic disorders towards improving outcome: the controversial issue of galactosaemia.
UNLABELLED: Galactosaemia due to galactose-1-phosphate uridyltransferase deficiency is a rare disease (1:40,000). Nationwide newborn screening for galactosaemia is performed in many countries; however, several countries do not screen for galactosaemia due to early manifestation of clinical symptoms and low incidence of the disease. In a German retrospective study, 148 galactosaemic patients born between 1955 and 1995, were evaluated. At least in Germany, newborn screening for galactosaemia, performed at day 5, was able to reduce or prevent the acute morbidity and mortality of the disease. The results should be even better if newborn screening takes place at day 3 using combined substrate screening and enzymatic testing for galactose-1-phosphate-uridyltransferase deficiency. CONCLUSION: Newborn screening for classical galactosaemia does not change the long-term complications of the disease such as speech disorders, mental retardation, ataxia and in females hypergonadotropic hypogonadism.
Adolescent↗
Two novel glucose-6-phosphate dehydrogenase variants found in newborn mass-screening for galactosaemia.
UNLABELLED: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive disorder in which haemolytic anaemia is the major symptom. The Beutler spot test employed in mass-screening for galactosaemia in newborns requires several intrinsic erythrocyte enzymes such as G6PD for its reaction and can theoretically detect G6PD deficiency apart from galactose-1-phosphate uridyltransferase deficiency. In this study, we detected two patients with G6PD deficiency using the quantitative Beutler test which was recently developed in our laboratory. Both patients lacked erythrocyte G6PD activity but exhibited no clinical symptoms. Molecular analysis in patients 1 and 2 revealed two novel missense mutations of C853T causing R285C and A1220C causing K407T, respectively. Molecular rather than enzymatic analysis was required in familial studies to detect and diagnose the carrier state. To date these patients have avoided oxidant stress and haemolytic diatheses have not been induced. CONCLUSION: Our results indicate that the quantitative Beutler test can detect glucose-6-phosphate dehydrogenase deficiency of class 1 and 2 and is therefore useful for early intervention and prevention of haemolytic diathesis in patients with this disorder.
Galactosemias↗
Manganese elevations in blood of children with congenital portosystemic shunts.
UNLABELLED: Magnetic response imaging has demonstrated increased signal intensities within the basal ganglia in patients with hepatic encephalopathy; the densities are considered to represent manganese deposition. We measured whole blood manganese concentrations in nine children with congenital portosystemic venous shunts detected by screening tests for galactosaemia. Beyond 1 year of age, these patients showed significantly higher manganese concentrations than controls (2.40 +/- 0.43 versus 1.48 +/- 0.38 micrograms/dl; P = 0.0001). Four of the nine patients were studied by magnetic response imaging. T1-weighted images showed increased signal intensities in the basal ganglia of those four patients, suggesting manganese accumulation. CONCLUSION: Children with congenital portosystemic venous shunts showed manganese elevations in blood and magnetic response imaging changes in the basal ganglia. These children should avoid excessive manganese intake.
Basal Ganglia↗