Endogenous galactose formation in galactose-1-phosphate uridyltransferase deficiency.

Patients with classical galactosaemia (galactose-1-phosphate uridyltransferase (GALT) deficiency) manifest clinical complications despite strict dietary galactose restriction. Therefore the significance of endogenous galactose production has been assessed. Previous in vivo studies primarily focused on patients homozygous for the most common genetic variant Q188R but little is known about other genetic variants.

Meal replacement reduces insulin requirement, HbA1c and weight long-term in type 2 diabetes patients with >100 U insulin per day.

Background: Despite high insulin doses, good glycaemic control is often lacking in type 2 diabetes patients and new therapeutic options are needed.

Methods: In a proof of principle study, an energy-restricted, protein-rich meal replacement (PRMR) was examined as a means of reducing insulin requirement, HbA1C and body weight. Obese type 2 diabetes patients (n = 22) with >100 U insulin per day replaced, in week 1, the three main meals with 50 g of PRMR (Almased-Vitalkost) each (= 4903 kJ day(-1) ).

Mechanisms underlying the onset of oral lipid-induced skeletal muscle insulin resistance in humans.

Several mechanisms, such as innate immune responses via Toll-like receptor-4, accumulation of diacylglycerols (DAG)/ceramides, and activation of protein kinase C (PKC), are considered to underlie skeletal muscle insulin resistance. In this study, we examined initial events occurring during the onset of insulin resistance upon oral high-fat loading compared with lipid and low-dose endotoxin infusion. Sixteen lean insulin-sensitive volunteers received intravenous fat (iv fat), oral fat (po fat), intravenous endotoxin (lipopolysaccharide [LPS]), and intravenous glycerol as control.

Indirect calorimetry in humans: a postcalorimetric evaluation procedure for correction of metabolic monitor variability.

Background: Indirect calorimetry (IC) with metabolic monitors is widely used for noninvasive assessment of energy expenditure and macronutrient oxidation in health and disease.

Objective: To overcome deficiencies in validity and reliability of metabolic monitors, we established a procedure that allowed correction for monitor-specific deviations.

Design: Randomized comparative IC (canopy mode) with the Deltatrac MBM-100 (Datex) and Vmax Encore 29n (SensorMedix) was performed in postabsorptive (overnight fast >8 h) healthy subjects (n = 40).

Differential glycomics of epithelial membrane glycoproteins from urinary exovesicles reveals shifts toward complex-type N-glycosylation in classical galactosemia.

A variety of genetic variations in the galactose-1-phosphate uridyltransferase (GALT) gene cause profound activity loss of the enzyme and acute toxic effects mediated by accumulating metabolic intermediates of galactose in newborns induced by dietary galactose. However, even on a severely galactose-restricted diet, patients develop serious long-term complications of the CNS and ovaries, which may result from damaging perturbations in cell biology caused by endogenously synthezised galactose. Under galactose stress, the cosubstrate of GALT, galactose-1-phosphate, accumulates and disturbs catabolic and anabolic pathways of the carbohydrate metabolism with potential effects on protein glycosylation and membrane localization of glycoprotein receptors, like the epidermal growth factor receptor.

Features and outcome of galactokinase deficiency in children diagnosed by newborn screening.

Galactokinase deficiency (GALK-D), an autosomal recessive disorder in the Leloir pathway, results in accumulation of galactose, galactitol, and galactonate and leads to early onset of juvenile bilateral cataract. Highest incidence of GALK-D is found in Romani populations. The migration wave due to the Yugoslavian civil war has changed the spectrum of inborn errors of metabolism within Europe.

Longitudinal assessment of intellectual achievement in patients with classical galactosemia.

Objective: To conduct a longitudinal assessment of long-term cognitive outcome in patients with classical galactosemia.

Methods: Inclusion criteria were (1) previous assessment of IQ dating back >10 years with tests being comparable with the recent German tests HAWIK-III and HAWIE-R, (2) absence of illnesses other than galactosemia, (3) absence of foreign language problems, (4) enzymatic-metabolic proof of classical galactosemia, (5) compliance with dietary therapy, and (6) written informed consent. Twenty-three patients who fulfilled these criteria were found.

Urinary excretion of pentose phosphate pathway-associated polyols in early postnatal life.

Background: Two new inborn errors in the pentose phosphate pathway have been described: ribose-5-isomerase deficiency and transaldolase deficiency. These defects are characterized by accumulation of specific polyols in body fluids. Little is known about human polyol metabolism, but there are indications for a physiological role primarily during early development.

Biochemical monitoring of pregnancy and breast feeding in five patients with classical galactosaemia--and review of the literature.

Pregnancy, delivery, and postpartal metabolic control was monitored biochemically in five patients (22-38 years of age) with clinically, enzymatically, and genotypically established classical galactosaemia and good dietary compliance. Three of the patients performed breast feeding of their newborns. Monitoring parameters were galactose-1-phosphate and galactitol concentrations in erythrocytes and urinary excretion of galactose, galactitol, galactonate, and lactose.

Description of the mutations in 15 subjects with variant forms of maple syrup urine disease.

Background: In maple syrup urine disease (MSUD), disease-causing mutations can affect the BCKDHA, BCKDHB or DBT genes encoding for the E1 alpha, E1 beta and E2 subunits of the multienzyme branched-chain 2-keto acid dehydrogenase (BCKD) complex.

Aim: The aim of this study was to screen DNA samples of 15 subjects with distinct well-characterized variant MSUD phenotypes for mutations in the three genes in order to demonstrate a potential correlation between specific nucleotide changes and particular variant phenotypes.

Methods: The exonic coding sequences of all three genes were studied using genomic DNA and cellular RNA derived from peripheral blood leukocytes.

Urinary excretion of the nitrotyrosine metabolite 3-nitro-4-hydroxyphenylacetic acid in preterm and term infants.

Background: Newborn infants are exposed to various sources of oxidative and/or nitrative stress, which refers to either oxidation and/or nitration of endogenous proteins including loss of their original function. Nitrative stress is predominantly caused following synthesis of peroxynitrite. Particularly preterm infants with immature defense mechanisms against free radical injury appear at risk.

Variant maple syrup urine disease (MSUD)--the entire spectrum.

Background: In the rare inborn autosomal recessive disorder maple syrup urine disease (MSUD) the accumulation of the branched-chain amino acids (BCAAs) and their metabolic products results in acute and chronic brain dysfunction. About 20% of the patients suffer from non-classic variant forms of MSUD of different clinical severity.

Aim: Up to now variant cases have mostly been published as individual case reports; the aim of this study was to give a comparative description of 16 individuals (aged 6-30 years) with different forms of variant MSUD.

Impact of longitudinal plasma leucine levels on the intellectual outcome in patients with classic MSUD.

Maple syrup urine disease (MSUD) is an inherited deficiency of branched chain alpha-ketoacid dehydrogenase (BCKDH) activity impairing the degradation of the branched chain amino acids valine, leucine, and isoleucine. Classic MSUD may lead to severe neonatal encephalopathy including coma and impaired cognitive outcome in later life. Early start of dietary treatment and careful metabolic control may improve the outcome of patients with classic MSUD.

Maple syrup urine disease-treatment and outcome in patients of Turkish descent in Germany.

Maple syrup urine disease (MSUD) is a rare autosomal recessive disorder that causes acute and chronic brain dysfunction because of a neurotoxic effect of the accumulating branched chain amino acids (BCAA) and their corresponding keto acids. Aim of the treatment is a rapid reversal of the neonatal decompensation and a stable long-term metabolic control obtained by a carefully adjusted BCAA-low diet. In optimally treated patients, an unimpaired neurological and intellectual outcome is possible.

Galactonate determination in urine by stable isotope dilution gas chromatography-mass spectrometry.

A stable isotope dilution assay was developed for the sensitive determination of D-galactonic acid. D-[U-13C(6)]galactono-1,4-lactone was prepared as internal standard. Unlabelled and U-13C-labelled D-galactonic acid species were converted to the N-(1-butyl)galactonamide pentaacetate derivatives and assessed by gas chromatography-mass spectrometry (GC-MS).

Age dependence of endogenous galactose formation in Q188R homozygous galactosemic patients.

The age dependence of endogenous galactose formation was investigated in Q188R homozygous galactosemic patients (n=18; 4-38 years) using the primed continuous infusion approach with D-[1-13C]galactose as a substrate. Studies were conducted under postabsorptive conditions (fasting >10h) and good metabolic control. In the patients, the release of galactose from endogenous sources into plasma (R(a)) decreased with age and ranged from 4.

Stable-isotope dilution analysis of galactose metabolites in human erythrocytes.

An established gas chromatography/mass spectrometry (GC/MS) method, devised for stable-isotope dilution analysis of plasma galactose, was developed to allow determination of erythrocyte (red blood cell, RBC) concentrations of galactose-1-phosphate and other primary metabolites relevant in galactosaemia. Galactose-1-phosphate was enzymatically converted to galactose, and the aldononitrile pentaacetate derivative was separated by gas chromatography and determined by mass spectrometry using chemical ionisation and selected ion monitoring of the [MH-60](+) ion. U-(13)C-Labelled standard was used for quantification.

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.

Identification of twelve novel mutations in patients with classic and variant forms of maple syrup urine disease.

Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder of panethnic distribution caused by a deficiency of the activity of branched-chain alpha-ketoacid dehydrogenase (BCKD) complex. Mutations in the human BCKD genes E1alpha (BCKDHA), E1beta (BCKDHB) and E2 (DBT) are known to result in MSUD, referred to as type Ia, Ib and II mutations respectively. In this study 16 patients with the classic severe form of MSUD and three patients with milder variant forms of the disease were investigated for mutations in the E1alpha-, E1beta- and E2-gene by single-strand conformation polymorphism (SSCP) analysis and DNA sequencing.

Whole-body L-leucine oxidation in patients with variant form of maple syrup urine disease.

Whole-body L-leucine oxidation was assessed in patients with maple syrup urine disease of different severity using oral L-[1-(13)C]leucine bolus tests (38 micromol/kg body weight). Residual whole-body L-leucine oxidation was estimated on the basis of the 3-h kinetics of (13)CO(2) exhalation and (13)C-isotopic enrichment in plasma 4-methyl-2-oxopentanoate using a noncompartmental mathematical approach. In four patients with classical maple syrup urine disease (two females and two males; mean age, 13 +/- 5 y; range, 7--17 y), L-leucine oxidation was too low to be measurable.

Branched-chain L-amino acid metabolism in classical maple syrup urine disease after orthotopic liver transplantation.

We characterized the effect of orthotopic liver transplantation on the catabolism of branched-chain L-amino acids in a female patient with classical form of maple syrup urine disease. Transplantation was performed at the age of 7.4 years due to a terminal liver failure triggered by a hepatitis A infection.