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Biomedical subjects

G F Hoffmann

Publications and source records attributed to G F Hoffmann.

At least 37 records · Page 2Linked to original sources
PubMed2004

Modulation of glutamatergic and GABAergic neurotransmission in glutaryl-CoA dehydrogenase deficiency.

Although the precise mechanisms underlying the CNS degeneration of patients with glutaryl-CoA dehydrogenase (GCDH) deficiency are still the subject of intense debate, many studies have highlighted that excitotoxicity plays a fundamental role in the neuropathology of this disease, particularly involving the N-methyl-D-aspartate receptor subtype of ionotropic glutamate receptors. Modulation of the glutamatergic system by these compounds involves an inhibition of glutamate uptake into synaptosomes and synaptic vesicles, and a decrease in glutamate binding. Furthermore, glutaric and 3-hydroxyglutaric acids inhibit glutamate decarboxylase, the key enzyme of GABA synthesis, and striatal GABAergic medium-spiny neurons are highly vulnerable to 3-hydroxyglutaric acid-induced neurotoxicity. In conclusion, glutaric acid and 3-hydroxyglutaric acid induce an imbalance in glutamatergic and GABAergic neurotransmission.

Amino Acid Metabolism, Inborn Errors↗
PubMed2004

Challenges for basic research in glutaryl-CoA dehydrogenase deficiency.

During the last decades, efforts have been made to elucidate the complex mechanisms underlying neuronal damage in glutaryl-CoA dehydrogenase deficiency. A combination of in vitro and in vivo investigations have facilitated the development of several hypotheses, including the probable pathogenic role of accumulating glutaric acid and 3-hydroxyglutaric acid. However, there are still many shortcomings that limit an evidence-based approach to treating this inborn error of metabolism. Major future goals should include generation of a suitable animal model for acute striatal necrosis, investigation of the formation, distribution and exact intra- and extracellular concentrations of accumulating metabolites, a deeper understanding of striatal vulnerability, and systematic investigation of effects on cerebral gene expression during development and of the modulatory role of inflammatory cytokines.

Amino Acid Metabolism, Inborn Errors↗
PubMed2004

Neonatal screening for glutaryl-CoA dehydrogenase deficiency.

Acute encephalopathic crisis in glutaryl-CoA dehydrogenase deficiency results in an unfavourable disease course and poor outcome, dominated by dystonia, feeding problems, seizures and secondary complications, and quite often leading to early death. The prerequisite for the prevention of irreversible brain damage in this disease is the detection of affected patients and initiation of treatment before the manifestation of such crisis. Apart from macrocephaly there are no signs or symptoms characteristic for this disease in presymptomatic children and, thus, they are usually missed. In some countries, implementation of extended neonatal screening programmes using electrospray ionization tandem mass spectrometry (ESI-MS/MS) allows detection of affected newborns and start of therapy before onset of neurological complications. This article summarizes recent strategies, pitfalls and shortcomings of a mass screening for glutaryl-CoA dehydrogenase deficiency using ESI-MS/MS. Furthermore, an alternative strategy, namely DNA-based neonatal screening for the Oji-Cree variant of this disease, is demonstrated. An optimization of diagnostic as well as therapeutic procedures must be achieved before GCDH deficiency unequivocally fulfills the criteria of a reliable and successful newborn screening programme.

Amino Acid Metabolism, Inborn Errors↗
PubMed2004

Maintenance treatment of glutaryl-CoA dehydrogenase deficiency.

This paper summarizes the published experience as well as results of the 3rd International Workshop on Glutaryl-CoA Dehydrogenase Deficiency held in October 2003 in Heidelberg, Germany, on the topic treatment of patients with glutaryl-CoA dehydrogenase (GCDH) deficiency. So far no international recommendation for treatment of GCDH deficiency exists. Such an approach is hampered by several facts, namely the lack of an in-depth understanding of the pathophysiology of the disease, the lack of prospective studies, including the evaluation of drug monotherapy, and lack of objective documentation of clinical changes (e.g. video documentation) during pharmacotherapy.

Amino Acid Metabolism, Inborn Errors↗
PubMed2004

Emergency treatment in glutaryl-CoA dehydrogenase deficiency.

The history of glutaryl-CoA dehydrogenase deficiency is determined by acute encephalopathic crises that are precipitated by common febrile diseases, vaccinations or surgical interventions during infancy and early childhood. Such crises result in an irreversible destruction of the basal ganglia (in particular of the putamina), and consequently dystonia, dyskinesia and choreoathetosis. Secondary complications include feeding and speech problems, failure to thrive, recurrent aspiration, immobilization, severe motor deficits and early death. It is generally accepted that maintenance treatment based on dietary lysine or protein restriction and supplementation with carnitine (and riboflavin) is insufficient to prevent acute crises during intercurrent illnesses or conditions that enhance catabolic state. Consequently, outpatient and inpatient emergency therapies have been implemented. The present review describes a recommended approach to emergency therapy for this disease.

Amino Acid Metabolism, Inborn Errors↗
PubMed2004

Management of movement disorders in glutaryl-CoA dehydrogenase deficiency: anticholinergic drugs and botulinum toxin as additional therapeutic options.

Glutaric aciduria type I is an inborn error of metabolism due to the deficiency of glutaryl-CoA dehydrogenase, an enzyme responsible for the catabolism of lysine, hydroxylysine and tryptophan. The most important neurological symptoms include dyskinesia and dystonia, which can be focal, segmental or generalized. Treatment of the extrapyramidal syndrome is often unsatisfactory. We report our experience in the treatment of generalized and focal dystonia with anticholinergic drugs and botulinum toxin type A, respectively. Both therapies proved beneficial.

Adolescent↗
PubMed2004

Looking forward--an evidence-based approach to glutaryl-CoA dehydrogenase deficiency.

Three decades after the first description of glutaryl-CoA dehydrogenase deficiency, major progress has been achieved in the prevention of acute striatal necrosis and neurological sequelae in affected children, if diagnosis is made early and treatment is started before manifestation of acute encephalopathic crises. However, all concepts for diagnostic work-up, monitoring, and treatment are solely experience-based, and 10-35% of early-diagnosed children do not or only incompletely benefit from the current management. They still develop neurological deterioration and sequelae despite early implementation of dietary treatment, carnitine supplementation and emergency treatment during acute intercurrent illnesses. International efforts should be made to move management of affected children from experience-based to evidence-based medicine. Major tools for this optimization are the establishment of an international patients' database, the implementation of an international prospective clinical study, and the development of international guidelines for diagnostic work-up, monitoring and therapy.

Amino Acid Metabolism, Inborn Errors↗
PubMed2003

Towards quality assurance in the determination of lysosomal enzymes: a two-centre study.

The definitive diagnosis of lysosomal storage disorders depends on the determination of enzymatic activities in cells, tissues or body fluids. At present, neither an evaluation of the different methods nor an interlaboratory quality assurance scheme is available. We have therefore determined the activities of total hexosaminidase, hexosaminidase A and beta-galactosidase in the same samples (n = 15) at two metabolic centres in Germany. Three different enzymatic methods were employed, two of which were based on leukocytes as enzyme source and one on dried blood spots. The results obtained by the two different methods using leukocytes proved comparable. In contrast, assays with dried blood spots showed poor correlation with results from leukocytes, possibly because enzymatic activity in dried blood is mainly derived from soluble plasma proteins. Nevertheless, accurate detection of a true enzyme deficiency was also possible in dried blood spots. All enzymes were highly stable when mailed frozen (recovery 98-120%). Enzymatic activities in dried blood samples were also stable at room temperature and were not affected even by exposure to elevated temperatures (50 degrees C for 3 h). Dried blood seems to be especially well suited for mailing from distant healthcare facilities, although more accurate results can be expected from leukocytes. In summary, comparability and pitfalls within a lysosomal quality assurance programme were evaluated.

Adult↗
PubMed2003

Phenylalanine can be detected in brain tissue of healthy subjects by 1H magnetic resonance spectroscopy.

Transport of phenylalanine (Phe) and the other large neutral amino acids across the blood-brain barrier plays a crucial role in the pathogenesis of phenylketonuria (PKU). Thus, investigation of Phe transport kinetics by means of proton magnetic resonance spectroscopy (1H MRS) became an important research area in the mid 1990s. As 1H MRS measurements of brain phenylalanine are restricted to tissue concentrations above 100-150 micromol/kg wet weight, this approach was possible only in PKU patients, and comparison with healthy controls was not achieved. Using standardized single-dose oral Phe loading in three healthy subjects, it was shown that Phe values increase steeply, peak at about 1 h post load, and decrease thereafter. In a single case study, repetitive Phe loading was then performed to achieve a plateau of high blood Phe concentrations for several hours. It was demonstrated that detection and monitoring of brain Phe concentrations is feasible by means of 1H MRS. This approach constitutes a prerequisite for describing carrier kinetics in health.

Adult↗
PubMed2003

Glutaryl-CoA dehydrogenase deficiency: region-specific analysis of organic acids and acylcarnitines in post mortem brain predicts vulnerability of the putamen.

The neurometabolic disorder glutaryl-CoA dehydrogenase (GCDH) deficiency is biochemically characterised by an accumulation of the marker metabolites 3-hydroxyglutaric acid, glutaric acid, and glutarylcarnitine. If untreated, the disease is complicated by acute encephalopathic crises, resulting in neurodegeneration of vulnerable brain regions, in particular the putamen. 3-hydroxyglutaric acid is considered the major neurotoxin in this disease. There are only preliminary data concerning glutaric acid concentrations in the brains of affected children and the distribution of 3-hydroxyglutaric acid and glutarylcarnitine has not been described. In the present study, we investigated post mortem the distribution of 3-hydroxyglutaric and glutaric acids as well as glutarylcarnitine in 14 different brain regions, internal organs, and body fluids (urine, plasma, cerebrospinal fluid) in a 14-year-old boy. 3-Hydroxyglutaric acid showed the highest concentration (62 nmol/g protein) in the putamen among all brain areas investigated. The glutarylcarnitine concentration was also highest in the putamen (7.1 nmol/g protein). We suggest that the regional-specific differences in the relative concentrations of 3-hydroxyglutaric acid contribute to the pattern of neuronal damage in this disease. These results provide an explanatory basis for the high vulnerability of the putamen in this disease, adding to the strong corticostriatal glutamatergic input into the putamen and the high excitotoxic susceptibility of neostriatal medium spiny neurons.

Acidosis↗
PubMed2003

Vitamin D and dexamethasone inversely regulate parathyroid hormone-induced regulator of G protein signaling-2 expression in osteoblast-like cells.

The PTH/PTHrP receptor stimulates both adenylate cyclase- and phospholipase C-dependent signaling pathways via different G proteins. The biological actions of PTH on bone are modified by steroid hormones. PTH induces expression of regulator of G protein signaling (RGS)-2, a putative preferential inhibitor of G(q)-mediated phospholipase C activation. We investigated whether steroid hormones interfere with PTH signaling by modulating PTH-induced RGS-2 expression in osteoblast-like UMR 106-01 cells. PTH (1-34) rapidly and transiently induced expression of RGS-2 mRNA and protein via the cAMP/protein kinase A pathway within 30 min, with maximal protein abundance after 2 h. PTH-induced RGS-2 preferentially bound to Galpha(q), compared with Galpha(s) protein. 1,25-(OH)(2)D(3) pretreatment enhanced PTH-induced RGS-2 mRNA and protein accumulation, whereas dexamethasone preincubation had an attenuating effect. These effects were due to modulation of the RGS-2 gene transcription rate, which increased by 35% with 1,25-(OH)(2)D(3) and decreased by 63% with dexamethasone pretreatment. RGS-2 mRNA half-life was not affected by either steroid. The transcriptional effects of dexamethasone and 1,25-(OH)(2)D(3) were independent of PTH/PTHrP receptor activation and were not explained by effects on cAMP accumulation, cAMP response element-binding protein expression or phosphorylation, or the abundance of the osteoblast-specific transcription factor core-binding factor alpha (CBFa1/Runx2), a known activator of RGS-2 expression. In conclusion, glucocorticoids and 1,25-(OH)(2)D(3) inversely modulate PTH-induced RGS-2 gene transcription. Regulation of RGS-2 may constitute a novel mechanism by which steroids modulate signaling via the PTH/PTHrP receptor and other G protein-coupled receptors in bone.

Animals↗
PubMed2002

[CDG (congenital disorders of glycosylation). Differential hereditary ataxia in adulthood diagnosis].

Congenital disorders of glycosylation (CDG) are a group of hereditary multisystem diseases due to different defects of enzymes or transport molecules involved in the synthesis of glycoproteins. CDG-la is the most common subtype, with cerebellar ataxia as the main neurological symptom. Currently there is little information about CDG-la manifestation in adulthood. Here we present two sisters in whom the diagnosis of CDG-la was made in the fourth decade of life and who to our knowledge are the oldest known patients with the disorder in Germany. The clinical course of the disease was typical, although less severe than previously described. The carbohydrate-deficient transferrin (CDT) level was increased but lower than in other CDG patients. Isoelectric focusing of transferrin revealed changes typical of CDG, whereas those of alpha 1-antitrypsin were only moderately pathologic. This might be due to the milder manifestation of the disease in our patients or it could be indicative of a stabilization of the disease after puberty. The CDG should be included in the differential diagnostic workup of hereditary cerebellar ataxia in adults.

Adult↗
PubMed2002

A new case of CDG-x with stereotyped dystonic hand movements and optic atrophy.

We report the clinical findings and the diagnostic work-up of a 17-month-old girl with CDG-x. Predominant clinical signs were, besides psychomotor retardation and truncal hypotonia, stereotyped dystonic hand movements and ophthalmological abnormalities such as optic atrophy, nystagmus and strabismus. Other symptoms that are often found in patients with CDG were not present, such as seizures, microcephaly, cerebellar hypoplasia, dysmorphic features, hepatointestinal disease, coagulopathy or multiorgan involvement. Isoelectric focusing (IEF) of the patient's serum showed a marked elevation of disialotransferrin, thus confirming an IEF type 1 pattern. A generalized glycosylation defect was confirmed also by IEF of a further glycoprotein (alpha1-antitrypsin), an increased carbohydrate deficient transferrin (CDT) serum concentration and an increased CDT/transferrin ratio. All known types of CDG-I, secondary glycosylation abnormalities and variants of amino acid sequence were excluded.

Dystonia↗
PubMed2002

Neurotransmitter metabolites in CSF: an external quality control scheme.

We report an international external quality control scheme on neurotransmitter metabolites in cerebrospinal fluid (CSF). The neurotransmitter metabolites homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) are analysed to diagnose inborn errors of neurotransmitter metabolism. HVA is the catabolite of dopamine; 5-HIAA is the catabolite of serotonin; and MHPG is the catabolite of noradrenaline. In the first phase, 12 laboratories from six countries participated in this special quality control scheme to define the present state of the art and achieve harmonization in analytical outcome and interpretation. In the second part, recoveries, dilutions and methods for sample preparation were compared. The results of 3 of 12 laboratories were excluded because of unacceptable intralaboratory coefficients of variations (CV) for HVA and/or 5-HIAA. The inter- and intralaboratory CVs, the linearity and the recovery were acceptable for the other laboratories for both parameters. Unacceptable differences in the reference ranges between laboratories, leading to differences in interpretation of the results, became obvious. There was a significant improvement of the interlaboratory CV for HVA after standardization with a calibrator. The reproducibility of MHPG measurement appeared to be adequately established in only two laboratories and recovery was low in all five measuring this metabolite. The quality control scheme is an invaluable tool for controlling the analytical outcome and providing support to laboratories to improve their quality.

Algorithms↗
PubMed2002

Glutaric aciduria type III: a distinctive non-disease?

Glutaric aciduria type III is a rare metabolic abnormality leading to persistent isolated glutaric acid excretion. We report the clinical and biochemical phenotypes of three affected children. The first patient is a boy with dysmorphic features and a chromosomal deletion (monosomy 6q26-qter) in whom a persistent glutaric aciduria (500 mmol/mol creatinine, normal <10) was detected during a routine metabolic investigation. The second boy suffered from acute gastroenteritis and hyperthyroidism, when an excessively high urinary glutaric acid excretion was identified (1460 mmol/mol creatinine). The third patient is a girl with constantly elevated glutaric acid in her urine (290 mmol/mol creatinine) but no symptoms of significant disease. In all our patients, glutaric aciduria type I (glutaryl-CoA dehydrogenase deficiency), glutaric aciduria type II (multiple acyl-CoA dehydrogenation defect), and secondary forms of glutaric aciduria (for example due to intestinal infections or mitochondrial dysfunction) could be excluded. Loading with the precursor amino acid lysine in all patients as well as with pipecolic acid in the third case led to an increase in urinary glutaric acid excretion, proving the endogenous origin of glutarate. Glutaric aciduria type III (a defect reported to be caused by peroxisomal glutaryl-CoA oxidase deficiency) is our presumptive diagnosis. However, peroxisomal glutaryl-CoA oxidase is not well characterized and no reliable approach for the direct determination of this enzyme is available to us. To our knowledge, in the English language literature only a single patient with glutaric aciduria type III has been described. Our cases reported here confirm the earlier assumption that glutaric aciduria type III is not related to a distinctive phenotype. Glutaric aciduria type III appears to be a rare metabolic abnormality, presumably of peroxisomal metabolism. However, its pathophysiological impact still needs further investigation.

Amino Acid Metabolism, Inborn Errors↗
PubMed2002

Emergency management of inherited metabolic diseases.

Inherited metabolic diseases with acute severe manifestations can be divided into five categories: (1) disorders of the intoxication type, (2) disorders with reduced fasting tolerance, (3) disorders with disturbed energy metabolism, (4) disorders of neurotransmission and (5) disorders in which no specific emergency treatment is available. Diagnostic emergency laboratory evaluation should cover all differential diagnoses that are therapeutically relevant and should always include ammonia, glucose, lactate and acid-base status as well as testing the urine for ketones. These are indispensable for planning and conducting the first steps of metabolic emergency treatment and should be available within 30 min. According to the clinical situation and biochemical derangement, special metabolic investigations must be initiated in parallel. These include acylcarnitine profiling with tandem mass spectrometry (in plasma or dried blood spots) and analysis of amino acids in plasma and of organic acids in urine. The results of all laboratory investigations relevant to the diagnosis of metabolic disorders for which specific emergency therapy exists should be available within 24 h. There is general agreement with regard to some therapeutic strategies that are clearly explained by pathophysiology: in disorders with endogenous intoxication, anabolism must be promoted and specific detoxification measures initiated. In disorders with reduced fasting tolerance, administration of glucose at the rate of hepatic glucose production forms the basis of treatment. Correction of acidosis is a major goal in disorders with disturbed mitochondrial energy metabolism, while glucose supply may have to be limited. Many current therapeutic strategies are based on case reports and personal experiences at different metabolic centres. The aim of devising the 'best' management is often hampered by the lack of objective evidence of efficacy.

Emergency Medical Services↗
PubMed2002

Congenital disorder of glycosylation IId (CDG-IId) -- a new entity: clinical presentation with Dandy-Walker malformation and myopathy.

A 1.5-year-old boy with macrocephaly due to a Dandy-Walker malformation presented with progressive hydrocephalus, extensive muscular hypotonia, transient cholestatic syndrome, extensive coagulation abnormalities and elevated creatine kinase indicating myopathy. Diagnostic work-up indicated a congenital disorder of glycosylation (CDG, formerly carbohydrate deficient glycoprotein syndrome). The serum transferrin pattern obtained by automated isoelectric focusing (IEF) showed an hitherto unreported pattern with strongly elevated tri-, di-, mono- and asialotransferrin bands, increasing in this order together with markedly decreased tetrasialotransferrin. Investigation of two additional glycoproteins, alpha(1)-antitrypsin and alpha(1)-antichymotrypsin, confirmed a generalised defect of glycosylation. All known glycosylation defects could be ruled out by enzymatic analyses in either leukocytes or fibroblasts or by the results obtained by IEF. SDS-electrophoresis demonstrated a marked difference in the molecular weight of transferrin, suggesting the lack of parts or of all oligosaccharide chains. The defect could be delineated to a deficiency of beta-1,4-galactosyltransferase (E.C.2.4.1.38) due to a homozygous insertion (1031 - 1032 insC). Details of the biochemical and molecular findings will be described elsewhere.

Adolescent↗