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Inborn Errors of Metabolism
Published in Praveen S. Goday, Cassandra L. S. Walia, Pediatric Nutrition for Dietitians, 2022
Surekha Pendyal, Areeg Hassan El-Gharbawy
To be used for energy, galactose needs to be converted to glucose via the Leloir pathway in the liver (Figure 23.2). Defects in three different enzymes: galactose-1-phosphate uridyl transferase (GALT), galactokinase, and galactose epimerase (GALE) can occur in this pathway that can result in galactosemia. Of these, GALT deficiency is the most common and has significant genotype-phenotype correlation based on residual enzyme activity.
Galactosemia
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop
Galactosemia is an inborn error of carbohydrate metabolism that results from deficiency of galactose-1-phosphate uridyl transferase (EC 2.7.7.12) (Figure 57.1). The disorder was first described in 1935 by Mason and Turner [1]. They found the reducing sugar in the urine and characterized it chemically as galactose. It is now clear that galactosuria may also occur in galactokinase deficiency, and in uridinediphosphate-4-epimerase deficiency. The enzyme deficiency was discovered by Isselbacher and colleagues [2]. The pathway of galactose metabolism had been worked out a few years earlier by Leloir and by Kalckar and their colleagues [3, 4]. The first step in the utilization is its conversion to galactose-1-phosphate (Gal-1-P) [5], which is catalyzed by galactokinase:
Carbohydrate and glycosylation disorders
Published in Steve Hannigan, Inherited Metabolic Diseases: A Guide to 100 Conditions, 2018
In some countries this disorder is screened for as part of a newborn screening programme for congenital disorders. Depending on the screening methods used, the enzyme itself (GALT) or the concentration of galactose in the blood may be measured. The inding of GALT deiciency will conirm classical galactosaemia. Measurement of galactose levels will detect cases of galactokinase deiciency and epimerase deiciency as well as classical galactosaemia. The inding of excess galactose in the blood should be followed by measurement of GALT activity. Galactokinase deiciency and epimer-ase deficiency must be considered if GALT activity is normal in an infant with elevated galactose levels.
Centella asiatica prevents D-galactose-Induced cognitive deficits, oxidative stress and neurodegeneration in the adult rat brain
Published in Drug and Chemical Toxicology, 2022
Zeba Firdaus, Neha Singh, Santosh Kumar Prajapati, Sairam Krishnamurthy, Tryambak Deo Singh
A limited amount of D-gal is catabolized by D-galactokinase and galactose-1-phosphate uridyl transferase. The surplus D-gal is reduced to galactitol and stored inside the cell causing osmotic stress and generation of ROS (Hsieh et al. 2009, Li et al. 2016). The brain is very susceptible to oxidative stress owing to its higher oxygen consumption, iron content, polyunsaturated lipids, and poor antioxidant system. Hippocampal and cortical regions are particularly susceptible to oxidative damage, and cellular injury in these regions can decrease memory by compromising hippocampal synaptic plasticity (TERRY and PeÑa 1965). Thus, D-gal treatment induces oxidative stress and causes intolerable alterations in the cell that play a key role in aging, and ultimately ends with cell death (Finkel and Holbrook 2000).
Genetic disease is a common cause of bilateral childhood cataract in Denmark
Published in Ophthalmic Genetics, 2021
Line Kessel, Daniella Bach-Holm, Moug Al-Bakri, Laura Roos, Allan Lund, Karen Grønskov
Congenital and childhood cataracts are rare but globally the most important cause of treatable childhood blindness (1). The pooled prevalence of congenital cataract across studies is 4.24 per 10,000 (2). Childhood cataracts can be caused by a wide range of etiologies. Unilateral cataracts are often associated with eye malformations such as a persistent hyaloid artery and/or microphthalmia whereas bilateral cataracts are more often associated with genetic diseases including syndromes (3). Because of lack of systemic associations in unilateral cataract, it is generally agreed that these children do not require further work up (4). There is no general agreement to which extent systemic work up is necessary in children with bilateral cataracts. The American Association of Ophthalmology do not recommend systemic and laboratory evaluations in children with a family history and no other medical problems. In children without a family history, they recommend to perform a urine metabolic evaluation, to test for congenital infections and to do blood tests for calcium, phosphorus, glucose and galactokinase (5). Others suggest to include next generation sequencing (NGS) as first-line work-up for children with bilateral cataracts without a family history as it may dramatically alter the subsequent management of the children and families (6). A retrospective chart review found that a specific diagnosis could be made in 10/15 children using a NGS panel specific for cataract-related genes (7).
Exopolysaccharides metabolism and cariogenesis of Streptococcus mutans biofilm regulated by antisense vicK RNA
Published in Journal of Oral Microbiology, 2023
Yuting Sun, Hong Chen, Mengmeng Xu, Liwen He, Hongchen Mao, Shiyao Yang, Xin Qiao, Deqin Yang
Next, we explored the mechanism of ASvicK regulating biofilm and EPS formation. We found that overexpression of ASvicK generated impact on the EPS metabolism-related genes gtfB/C/D, ftf and vicK. Meanwhile, the ability to produce VicK protein and the enzyme activity of GTFs were diminished. Numerous studies have confirmed that VicK plays a crucial role in the biofilm formation of S. mutans and the expression of genes related to EPS metabolism [17,41]. Deletion of vicK results in down-regulation of gtfD, ftf and gbpB [35]. These studies are consistent with the results that down-regulation of the vicK gene in our ASvicK strain carried out decreased expression of gtfB/C/D and ftf. GTFs enzymatic activity was significantly reduced in ASvicK overexpressing strains, again confirming that ASvicK RNA affects EPS synthesis by affecting GTFs. In the previous results of GC-MS, the galactose fraction of ASvicK overexpressing strains increased. Lactose metabolism is mainly hydrolyzed into glucose and galactose-6-phosphate (Gal-6-P) through the tagatose pathway and LeIoir pathway [42,43], which is released from Lac-6-P. Glucose can be phosphorylated by galactokinase (GalK) before entering glycolysis [44,45]. In this study, the lacA/B/C/D/E/G/R genes involved in the lactose metabolism tagatose pathway and galK and galT gene expression was significantly increased. Therefore, lactose and galactose participate in the complex regulatory mechanism of EPS metabolism.