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The development of electroretinogram abnormalities and the possible role of polyol pathway activity in diabetic hyperglycemia and galactosemia.

This study examined the induction of electroretinogram abnormalities in hyperglycemia and the possible role of increased polyol pathway activity in the development of these changes. Both diabetic hyperglycemia and galactosemia caused the prolongation of peak latencies and in some cases a reduction in the amplitudes of oscillatory potentials on the b-wave. Diabetic hyperglycemia-associated abnormalities were prevented and normalized by insulin or ADN-138, an aldose reductase inhibitor. Galactosemia-induced abnormalities were inhibited by ADN-138, and were reversed either by ADN-138 treatment or by withdrawal of galactose from the diet. Polyol accumulation was prevented by insulin or ADN-138, and the elevated polyol level was reversed by insulin, ADN-138, or withdrawal of galactose in diabetic hyperglycemia and/or galactosemia. These results suggest that the increased polyol pathway activity in the hyperglycemia may be involved in the development of electroretinogram abnormalities similar to those in human diabetes; therefore, ADN-138 could be a useful drug for therapy of retinopathy in the early diabetic stage.

Animals↗

Characterization of a novel biochemical abnormality in galactosemia: deficiency of glycolipids containing galactose or N-acetylgalactosamine and accumulation of precursors in brain and lymphocytes.

Classic galactosemia, an inborn error of human galactose metabolism, is characterized by a deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT). The current model for the pathophysiology of this disease ascribes most of its symptoms to the toxicity of intracellular galactose-1-phosphate (Gal-1-P), one of the substrates of GALT which accumulates in the untreated disease state. Recently, a reduction in the intracellular concentration of UDP-Gal (uridine diphosphogalactose), one of the products of GALT, has been described in treated galactosemic patients. We investigated whether galactosemic patients might also have reduced amounts of those macromolecules that depend on UDP-Gal for their biosynthesis. We report a reduction in glycolipids that contain either galactose or its derivative N-acetylgalactosamine and an accumulation of the precursors to these compounds in the brain of a neonate with galactosemia. We also found an imbalance in glycolipids in galactosemic lymphoblasts. This novel biochemical abnormality observed in galactosemic patients is not addressed by dietary galactose-restriction therapy and could explain some of the chronic neurologic and other complications of galactosemia.

Acetylgalactosamine↗

Short-term exogenous galactose supplementation does not influence rate of appearance of galactose in patients with classical galactosemia.

INTRODUCTION: Recently, evidence has been presented that adult patients with classical galactosemia have higher than expected galactose tolerance. This may be caused by a decrease of endogenous galactose production with ageing. Alternatively, suppression of endogenous galactose production by exogenous galactose might be implicated. The aim of this study was to determine if the rate of appearance of galactose is suppressed by exogenous galactose. MATERIALS AND METHODS: Two adult patients with classical galactosemia and three healthy control subjects were given a primed continuous infusion of D-[1-13C]galactose to determine the rate of appearance of galactose (GAR, expressed as micromol/kg/h) before and during additional galactose supplementation. After initial assessment of GAR (GAR1), GAR was determined during doubled (GAR2) or quadrupled (GAR4) galactose infusion. RESULTS: GAR1 was 2.48 and 2.44 in patients 1 and 2, and 0.46, 0.34, and 0.39 in control subjects 1, 2, and 3, respectively. GAR(2) was 2.43 and 2.13 in patients 1 and 2, and 0.57, 0.38, and 0.47 in control subjects 1, 2, and 3, respectively. In patient 1 the experiment was repeated during quadrupled galactose infusion. Here GAR1 was 3.01 and GAR4 was 3.26. CONCLUSIONS: No significant differences between GAR before and during additional galactose infusion were found in patients and in control subjects. GAR1 was significantly higher in patients than in control subjects. We conclude that the rate of appearance of galactose is not influenced by exogenous galactose, at least under short-term conditions, in patients with classical galactosemia and in control subjects.

Adult↗

[Vitreous hemorrhage in a neonate with galactosemia. A case report].

Galactosemia is an inherited metabolic disorder due to a defect in one of the three enzymes required to fully metabolize the galactose in glucose: the galactose 1-phosphate uridyltransferase. Because this enzyme is present in the normal foetal liver since the tenth week of gestation, its defect cause congenital abnormality due to galactose accumulation, when the mother had taken milk during the pregnancy. It is mainly a liver pathology whereas the foetal cataract is rare. This latter is usually considered as the sole ophthalmic consequence of this disorder but exceptional ocular haemorrhages have also been described. We report the case of a neonate with galactosemia free from foetal cataract but presenting an unilateral vitreous haemorrhage. Retinal anomalies seen after vitrectomy are probably the source of the vitreous blood favoured by the coagulopathy associated with the neonatal disease. The causes of infant vitreous haemorrhages are often debated and their complications, especially severe amblyopia, require vitrectomy within the month following their discovery. In galactosemia, vitreous haemorrhage can be prevented by an early diagnosis and an appropriate treatment of the liver pathology.

Galactosemias↗

Hyperglycemia and development of glomerular pathology: diabetes compared with galactosemia.

Dogs were randomly assigned to experimental galactosemia or diabetes, or to a normal untreated group, and diabetic animals were then randomly assigned to either poor or good glycemic control. At five years duration, kidneys from the animals were compared by quantitative stereology. Glomerulopathy appeared in the poor control diabetes group, and the thickness of glomerular capillary basement membrane, the glomerular tuft volume, and the fraction of glomerulus occupied by mesangium were each significantly greater than normal. The capillary filtering surface area per glomerulus was supranormal also, but nonetheless was subnormal relative to glomerular volume. The development of glomerulopathy was significantly inhibited in dogs assigned to good glycemic control. In galactosemic animals, the basement membrane thickness was greater than normal, but the glomerular volume, fractional and absolute volumes of mesangium, and capillary filtering surface area remained normal. The polyol concentration in renal cortex seemed elevated by galactosemia no less than by diabetes, and was highest in galactosemia. The galactosemic animals are known to have developed a retinopathy morphologically comparable to that of diabetic patients and diabetic dogs. Thus, sequelae of hyperglycemia sufficient to produce glomerular basement membrane thickening and retinopathy proved not necessarily sufficient to produce the mesangial expansion and glomerular hypertrophy typical of diabetes.

Animals↗

Novel Proactive Speech-Language Intervention Is More Effective Than Usual Care: Randomized Controlled Trial of Babble Boot Camp for Infants With Classic Galactosemia.

PURPOSE: Speech and language disorders cannot be diagnosed and treated until children are approximately 2-4 years old. To investigate whether these disorders can be prevented, we developed and trialed Babble Boot Camp (BBC), the first proactive sustained intervention starting with precursor skills including cooing and babbling. METHOD: Participants were two randomly assigned groups of 22 infants with classic galactosemia, a metabolic disease with known risks for severe speech and language disorders. One group started BBC at under 6 months of age, and the other started at 15 months of age, both completing BBC at 24 months of age. Coached by a speech-language pathologist in weekly telehealth sessions, caregivers implemented BBC activities and routines daily at home. A typical control group and a group of children with classic galactosemia who received usual care participated as well. All children completed standardized assessments of speech and language at postintervention. RESULTS: Assessment scores showed that BBC was more effective than usual care for both intervention groups. Greatest benefits were seen in the group that started at or before 6 months of age, with a proportion of clinically concerning scores equal to that in the typically developing peers. No effects of sex, genotype, or milk consumption were evident in the outcomes. CONCLUSIONS: Findings motivate a paradigm shift from deficit-based to proactive approaches for infants with classic galactosemia. BBC is extensible to many other disorders, with trials currently underway for infants with Down syndrome and infants born preterm.

Humans↗

Delay of liver maturation as a cause of transient neonatal galactosemia.

BACKGROUND: Because a large amount of serum alpha-fetoprotein (alpha-FP) is synthesized in the liver of the fetus or premature newborn, high concentrations or delayed degradation of serum alpha-FP during the neonatal period may reflect hepatic immaturity. METHODS: In order to evaluate the relationship between transient neonatal galactosemia and delay of liver maturation, the concentration and half-life of serum alpha-FP during the neonatal period were measured in patients with transient galactosemia and in normal neonates. RESULTS: No significant differences were observed in the serum concentration of alpha-FP between normal and galactosemic patients less than 1 month of age. However, the half-life of serum alpha-FP was significantly longer in galactosemic patients between 15 and 60 days of age compared with age-matched normal neonates. CONCLUSION: Based on these results, we hypothesize that delay of liver maturation during the neonatal period, especially during the first 2 months after birth, can be a cause of transient neonatal galactosemia.

Galactose↗

Hypergonadotropic hypogonadism in female patients with galactosemia.

We evaluated gonadal function in 18 female and eight male patients with galactosemia due to transferase deficiency; it was normal in the males, but 12 females had signs of hypergonadotropic hypogonadism. All female patients had a 46,XX karyotype, normal levels of thyroid hormone and prolactin, and no anti-ovarian antibodies. The biologic activity of urinary gonadotropins was normal. Ultrasonography of the pelvis revealed that ovarian tissue was diminished or absent. Total estrogens increased in one of two patients after administration of human menopausal gonadotropin. The frequency of hypergonadotropic hypogonadism was higher in females in whom dietary treatment for galactosemia was delayed. Clinical course and mean erythrocyte galactose-1-phosphate and urinary galactitol levels did not correlate with ovarian function. We conclude that female patients with galactosemia have a high incidence of ovarian failure due to acquired ovarian atrophy. Galactose or its metabolites may be toxic to the ovarian parenchyma, particularly during the immediate neonatal period.

Adolescent↗

Risk factors for premature ovarian failure in females with galactosemia.

UNLABELLED: The risk for premature ovarian failure (POF) in females with galactosemia can be predicted by analyzing 3 areas of risk pathology: the patient's molecular genotype for galactose-1-phosphate uridyltransferase (GALT), alternate pathways for galactose metabolism, and the patient's environment at diagnosis and during treatment. STUDY DESIGN: Retrospective cross-sectional information was collected on 53 females with classic galactosemia, and their ovarian function was analyzed by determination of serum follicle-stimulating hormone and luteinizing hormone levels and by clinical observation. The associations were analyzed between POF and the mutations in GALT, the highest erythrocyte galactose-1-phosphate (Gal-1-P) level at diagnosis, the age at which dietary treatment was initiated, mean erythrocyte Gal-1-P level during treatment, and whole-body carbon 13-labeled galactose oxidation to (13)CO(2). RESULTS: The most prevalent mutation, Q188R, had a significant effect of genotype category (Q188R/Q188R, Q188R/Other, Other/Other) on POF (P =.04, Fisher exact test and an odds ratio of 8.3). Mean erythrocyte Gal-1-P level during treatment was a significant risk factor for POF (P =.04). Also, all patients studied with less than 5% total body oxidation of galactose to (13)CO(2) had POF, whereas those with more than 5% did not have POF (P =.008, Fisher exact test). CONCLUSION: The development of POF in females with galactosemia is more likely if the patient's genotype is Q188R/Q188R, if the mean erythrocyte Gal-1-P is >3.5 mg/dL during therapy, and if the recovery of (13)CO(2) from whole-body (13)C-galactose oxidation is reduced below 5% of administered (13)C-galactose.

Adolescent↗

Molecular basis for severe epimerase deficiency galactosemia. X-ray structure of the human V94m-substituted UDP-galactose 4-epimerase.

Galactosemia is an inherited disorder characterized by an inability to metabolize galactose. Although classical galactosemia results from impairment of the second enzyme of the Leloir pathway, namely galactose-1-phosphate uridylyltransferase, alternate forms of the disorder can occur due to either galactokinase or UDP-galactose 4-epimerase deficiencies. One of the more severe cases of epimerase deficiency galactosemia arises from an amino acid substitution at position 94. It has been previously demonstrated that the V94M protein is impaired relative to the wild-type enzyme predominantly at the level of V(max) rather than K(m). To address the molecular consequences the mutation imparts on the three-dimensional architecture of the enzyme, we have solved the structures of the V94M-substituted human epimerase complexed with NADH and UDP-glucose, UDP-galactose, UDP-GlcNAc, or UDP-GalNAc. In the wild-type enzyme, the hydrophobic side chain of Val(94) packs near the aromatic group of the catalytic Tyr(157) and serves as a molecular "fence" to limit the rotation of the glycosyl portions of the UDP-sugar substrates within the active site. The net effect of the V94M substitution is an opening up of the Ala(93) to Glu(96) surface loop, which allows free rotation of the sugars into nonproductive binding modes.

Crystallization↗

Tissue-specific effects of aldose reductase inhibition on fluorescence and cross-linking of extracellular matrix in chronic galactosemia. Relationship to pentosidine cross-links.

Chronic experimental hyperglycemia mediated by galactose has been shown to induce browning and cross-linking of rat tail tendon collagen that could be duplicated in vitro by nonenzymatic galactosylation. To investigate the nature of these changes, Sprague-Dawley rats were placed on a 33% galactose diet without and with sorbinil for 6 and 12 mo. Collagen-linked fluorescence and pentosidine cross-links increased with age and galactosemia in tail tendons (P less than 0.001) and skin but were essentially unresponsive to aldose reductase inhibition (ARI). In contrast, tendon breaking time in urea, a likely parameter of cross-linking, was markedly improved (P less than 0.001) by ARI. Fluorescence that was inhibited by sorbinil treatment was increased in pepsin and proteinase K digest of aortic tissue from galactosemic rats (P less than 0.001), but impaired enzymatic digestibility was not observed. Systolic blood pressure as potential consequence of aortic stiffening was not increased in galactosemia. These data suggest that fluorescence in skin and tendon might be in part due to advanced glycosylation and pentosidine formation because these were not decreased by ARI. However, they also suggest that nonfluorescent cross-links may also be forming because, in contrast to fluorescence, tail tendon breaking time was partly corrected by ARI. Thus, it appears that extracellular matrix changes in chronic galactosemia are complex, being partly attributable to advanced glycosylation and partly to polyol-pathway activation.

Aldehyde Reductase↗

Response of capillary cell death to aminoguanidine predicts the development of retinopathy: comparison of diabetes and galactosemia.

PURPOSE: To examine the relationship between early retinal capillary cell apoptosis and late histologic lesions of diabetic retinopathy and to compare the effects of aminoguanidine (AMG) on the retinopathies caused by diabetes and galactose feeding. METHODS: Rats with alloxan-induced diabetes and rats fed a 30% galactose diet (known to induce diabetic-like retinopathy) were assigned randomly to receive diet with (2.5 g/kg diet) or without AMG. After 6 to 8 months of diabetes or galactosemia, retinal trypsin digests were prepared, and capillary cell apoptosis was quantitated using the Tdt-mediated dUTP nick-end labeling (TUNEL) reaction in association with morphologic evidence of nuclear fragmentation. At 18 months duration, pericyte ghosts and acellular capillaries were quantitated in the isolated vasculature. Several advanced glycation end products (AGEs) were measured at 4 months of study and at 18 months of study by established methods to assess biochemical effects of AMG. RESULTS: As expected, both diabetic and galactosemic rats showed increased frequency of TUNEL-positive capillary cells at 6 to 8 months and vascular lesions characteristic of retinopathy at 18 months. AMG inhibited both the early apoptosis and late histopathology in the diabetic rats, but neither of these abnormalities in the galactosemic rats. In contrast to its preventative effect on retinopathy in the diabetic rats, AMG showed no inhibitory effect on levels of hemoglobin AGE, or tail collagen pentosidine, fluorescence, and thermal breaking time. Diabetes of 4 months' duration did not cause a detectable increase in retinal levels of several AGEs. CONCLUSIONS: The frequency of early apoptosis in retinal microvascular cells predicted the development of the histologic lesions of retinopathy in diabetes as well as in galactosemia. The beneficial effect of AMG on retinal lesions in diabetes is exerted on pathways that are either not operative or are less important in galactosemia and that may not relate to the accumulation of AGEs.

Animals↗

Screening for galactosemia: Philippines experience. Newborn Screening Study Group.

Galactosemia is an inborn error of galactose metabolism due to a deficiency of any of the galactokinase, galactose-1-phosphate uridyl transferase (GALT), or epimerase enzymes. The Philippines, with its pilot newborn screening project, has been screening for this disorder for 2 years now. A total of 62,841 babies have been screened using the galactose and galactose-1-phosphate spot test. Confirmatory testing is done by the newborn screening laboratory of the The New Children's Hospital in Westmead, Australia. Two cases of galactosemia: 1 classical galactosemia and 1 galactokinase deficiency have so far been confirmed. Clinical review, problems encountered, and management are described. Long-term outcome of these patients, however, is yet to be determined.

Female↗

[A case of atypical galactosemia(author's transl)].

The case of a male infant suffering from clinical manifest galactosemia in connexion with a disease of only about 70% in uridyltransferase activity is characterized as atypical galactosemia. As compared with the described "Indiana variant" of a galactosemic female infant showing an unstable uridyltransferase activity this case demonstrates an unchanged enzyme activity still after 72 hrs. The metabolic disease of this patient clearly demonstrated that the lack of a typical pronounced reduction of enzyme activity maybe not the leading criterion for excluding the clinical diagnosis of galactosemia. In the present case only the consistent galactose-free diet lead to the decisive improvement of the clinical picture. The investigation of the family revealed the typical pattern of an autosomal recessive mode of heredity.

Erythrocytes↗

Selective screening for neonatal galactosemia: an alternative approach.

UNLABELLED: No universal consensus exists for population-based neonatal screening for galactosemia. In our institution, selective screening for classical galactosemia is carried out on infants under 2 wk of age and those with symptoms suggestive of this disorder. Eighteen cases were diagnosed from 25,099 tests done; 17 were symptomatic at the time of diagnosis. CONCLUSION: We suggest that improved clinical vigilance and selective screening would identify most infants with severe galactosemia as early as a population-based program.

Biomarkers↗

Association of Escherichia coli sepsis and galactosemia in neonates.

Galactosemia in newborns and infants is associated with the following symptoms: jaundice, hepatomegaly, failure to thrive, feeding difficulties, hypoglycemia, convulsions, lethargy, amino-aciduria, cataracts, hepatic cirrhosis, ascites, and mental retardation. If the preliminary evaluation indicates galactosemia, there is high risk for E. coli sepsis and death. Strong consideration should therefore be given for early antibiotic therapy in infants with suspected galactosemia in spite of the absence of clinical signs or symptoms of sepsis.

Escherichia coli Infections↗

Diagnosis and management of galactosemia: an Egyptian experience.

OBJECTIVE: To screen normal and high risk Egyptian neonates for galactosemia. SUBJECTS AND METHODS: The study included 2238 neonates classified into two groups. Group I included screening of 1794 normal newborns. Group II included 374 high risk neonates (jaundice, hepatomegaly and failure to thrive). Group III 70 prematures. Total galactose was determined by enzymatic colourimetric method in dried blood spot (Quantase). The enzymes activities (uridyltransferase and epimerase) were measured using C14. RESULTS: One case of galactosemia was found in the first group and 26 cases in the second group. 19 patients suffered from uridyltransferase deficiency, the parents of 16 (88.8%) of this classic form were consanguineous and 5 (27.7%) parents had history of a previously affected child. Mean age of diagnosis was 3.8 month with a mean total gal value of 52.9 mg/dl. 10 (55.5%) of them have cataract. The other 8 affected neonates were epimerase deficiency patients. 5 (62.5%) of them born to consanguineous parents. Parents of the epimerase deficiency neonates have no previously affected children. Mean age of diagnosis was 7.2 month with a mean total gal of 17.5 mg/dl. All eight patients have cataract. CONCLUSION: Mass screening program is not available yet in Egypt. Screening of the high risk neonates is a priority. Diagnosis of different galactosemia forms is mandatory to structure the management strategy accordingly. (Fig. 4, Ref: 26.)

Egypt↗

Pitfalls in diagnosing galactosemia: false negative newborn screening following red blood cell transfusion.

Newborn galactosemia screening programs using the fluorescence spot test to detect red cell galactose-1-phosphate uridyltransferase activity are prone to inaccuracy if the screened infants have received blood transfusions. We describe an infant with galactosemia who received packed red cell transfusions in the first few days of life and was misdiagnosed after an initial positive screening test result. Although the patient was thought to have cytomegaloviral hepatitis, a percutaneous liver biopsy helped direct the evaluation toward identifying the galactosemia carrier state in both parents. This case report illustrates the need for careful consideration of the patient's history of transfusion of blood products when evaluating newborn screening results.

Blood Transfusion↗