bluuebunny/crossref_metadata_2025 huggingface dataset:
Both Intra- and Extracellular Ca2+ Participate in the Regulation of the Lateral Diffusion of the PDGF-β2 Receptor
Authors: Höddelius Pia , Lirvall Margareta , Wasteson Åke , Loitto Vesa , Magnusson Karl-Eric
Published: December 2002

When the receptors for platelet-derived growth factor (PDGF) are activatedthey aggregate, become tyrosine-phosphorylated and elicit a cascade ofdown-stream signals, including mobilization of Ca2+ from intra- andextracellular stores. Receptor mobility in the plane of the membrane isa prerequisite for receptor aggregation and further signalling. Using humanforeskin fibroblasts (AG 1523) and fluorescence recovery afterphotobleaching (FRAP), we therefore assessed the lateral mobilitycharacteristics of PDGF-β2 receptors by their diffusioncoefficient (D), and fraction of mobile receptors (R). This was done oncells stimulated with either normal human serum (NHS) or PDGF underdifferent Ca2+-conditions.

The results suggest that both intra- and extracellular free Ca2+influence the mobility characteristics of the PDGF-β2receptor. Interestingly, the extracellular Ca2+ seems to imposegeneral restrictions on the mobility of receptors, since R increased whenextracellular Ca2+ was quenched with EGTA, whereas intracellularclamping of Ca2+ transients with MABTAM (BAPT/AM) primarily affectedD. When both intra- and extracellular Ca2+ were quenced, D remainedlow and R high, further supporting the proposition that they achievedistinct effects. Inhibition of tyrosine phosphorylation with Erbstatin,partly inhibited the NHS effects and released PDGF-induced receptorimmobilization. Ratio imaging with Fura-2 displayed that both NHS and PDGFinduced changes in intracellular free [Ca2+]. In view of the presentdata it might have important effects on the state of the receptor in themembrane, for instance by regulating its lateral mobility, communicationwith other receptors and signalling functions in the membrane.
Personality profiles of mothers of children with mitochondrial disorders
Authors: Varvogli L. , Waisbren S. E.
Published: December 2002

Mothers of children with mitochondrial disorders, inherited neurodegenerative diseases, are faced with a frightening diagnosis and numerous demands associated with caring for these children. The psychological profile of mothers whose children carry a mitochondrial disorder is unknown. Forty‐two mothers of children with mitochondrial disorders were interviewed and administered the Minnesota Multiphasic Personality Inventory – Second Edition (MMPI‐2). Fifty‐six per cent of the mothers had scores in the pathological range on three or more scales, most notably on Hypochondriasis, Hysteria and Paranoia scales. The MMPI‐2 profile is associated with situational anxiety and stress or may be associated with carrier status characteristics. Whatever the cause, future studies need to determine whether supportive services can reduce the level of anxiety and stress in mothers of children with these disorders.
A Study of Membrane Activity in Rat Prostate Cancer Cells: An Evaluation of the FM1–43 Dye Technique
Authors: Mycielska Maria E. , Schäfer Monika , Fraser Scott P. , Djamgoz Mustafa B. A. , Bashford C. Lindsay
Published: December 2002

A study was initiated to test whether the FM1–43 dye technique could beapplied to the study of endocytic membrane activity in two rodent prostatecancer (MAT-LyLu and AT-2) cell lines of markedly different metastaticability. The lipophilic dye FM1–43, which has frequently been used tomonitor endo/exocytic activity in excitable cells was employed. We found,as in excitable tissues, that both strongly metastatic (MAT-LyLu) andweakly metastatic (AT-2) cells in culture take up FM1–43 to give vesicularstaining of a variable pattern, which appeared to differ between the twocell lines. However, unlike excitable tissues, neither cell linesubsequently released the dye. Indeed, both cell lines retained the dyethrough several rounds of cell division suggesting that dye incorporatedby cells does not enter the endo/exocytotic cycle. Uptake of dye wasindependent of temperature, Na+/K+ gradients, pH or metabolism. Wesuggest that passive accumulation of FM1–43 can occur in cancer cells andshould not, automatically, be interpreted as evidence of endocytosis.
Glutaric aciduria type I: From clinical, biochemical and molecular diversity to successful therapy
Authors: Hoffmann G. F. , Zschocke J.
Published: December 2002

The biochemical hallmark of glutaric aciduria type I (GA I) due to glutaryl‐CoA dehydrogenase deficiency is the accumulation of glutaric acid, and to a lesser degree of 3‐hydroxyglutaric and glutaconic acids. Abnormal metabolites vary from gross organic aciduria to only slightly or intermittently elevated or even normal excretion of glutaric acid, making the diagnosis sometimes difficult. Close to 100 pathogenic mutations have been identified in the gene encoding glutaryl‐CoA dehydrogenase. Specific mutations correlate with low or no excretion of glutaric acid, but there appears to be no correlation between genotype and clinical phenotype.

GA I causes unique age‐ and location‐specific neuropathological sequelae. Starting in the second half of gestation, maturation of the frontal and temporal cortex is hindered, leading to the characteristic appearance of frontotemporal atrophy. Between 6 and 18 months of age, relatively mild neurological symptoms may become exacerbated by fever or a catabolic state in the course of common infections or routine immunizations, by fasts required for surgery, or by minor head injuries. Putamen and caudate are destroyed, resulting in a permanent movement disorder that is similar to cerebral palsy and ranges from extreme hypotonia to choreoathetosis to rigidity with spasticity. Recently, the underlying pathophysiology could be delineated to an environmentally triggered age‐ and location‐specific overstimulation of the NMDA 2B receptor subtype.

Current therapy prevents brain degeneration in more than 90% of affected infants who are treated prospectively. Without treatment, more than 90% of affected children will develop severe neurological disabilities. Recognition of this disorder before the brain has been injured is essential to treatment. GA I may be recognized in routine neonatal screening performed with tandem mass spectrometry by an elevation of glutarylcarnitine. Where this is not done, timely diagnosis depends on the recognition of relatively nonspecific physical findings such as hypotonia, irritability, macrocephaly, on the detection of suggestive abnormalities in neuroimaging and on quantitative urinary organic acid analysis by gas chromatography ‐ mass spectrometry.
D‐2‐Hydroxyglutaric aciduria: Further clinical delineation
Authors: van der Knaap M. S. , Jakobs C. , Hoffmann G. F. , Duran M. , Muntau A. C. , Schweitzer S. , Kelley R. I. , Parrot‐Roulaud F. , Amiel J. , De Lonlay P. , Rabier D. , Eeg‐Olofsson O.
Published: December 2002

It has recently been recognized that D‐2‐hydroxyglutaric aciduria is a distinct neurometabolic disorder with a severe and a mild phenotype. Whereas the clinical and neuroimaging findings of the severe phenotype were homogeneous among the patients, the findings in the mild phenotype were much more variable, leaving the clinical picture poorly defined. We were able to collect the clinical, biochemical and neuroimaging data on an additional 8 patients with D‐2‐hydroxyglutaric aciduria, 4 with the severe and 4 with the mild phenotype. With the new information, it becomes clear that the mild phenotype shares the essential characteristics of the severe phenotype. The most frequent findings, regardless of the clinical phenotype, are epilepsy, hypotonia and psychomotor retardation. Additional findings, mainly occurring in the severe phenotype, are episodic vomiting, cardiomyopathy, inspiratory stridor and apnoeas. The most consistent MRI finding is enlargement of the lateral ventricles, occipital more than frontal. Regardless of the clinical phenotype, early MRI shows in addition subependymal cysts and signs of delayed cerebral maturation. Later MRI may reveal multifocal cerebral white‐matter abnormalities. Two patients had vascular abnormalities, but it is as yet unclear whether these are related to D‐2‐hydroxyglutaric aciduria or are incidental findings.
The Ca2+-Transporting Activity of Rat Liver Microsomes in Response to Protein Undernutrition: Implications for Liver Tumor Promotion
Authors: Adenuga Gbenga A.
Published: December 2002

The effect of protein undernutrition on the activity of the smoothendoplasmic reticulum (microsomal) Ca2+-ATPase (SERCA) wasinvestigated. After 12 weeks of ad libitum ingestion of low proteindiet (5% protein), a significant depression (p<0.05) of liver ERCa2+-ATPase activity (68.6% depression) was observed. However,no significant effects on cytochrome P450 activity and relative liverweight were found. It is proposed that low protein diet by inhibitingthe rat liver SERCA activity, might increase the cytosolic free calciumion concentration ([Ca2+]) and promote the development of livertumor. The possible mechanisms of low protein diet induced inhibition ofSERCA activity are highlighted.
3‐Methylglutaconic aciduria and hypermethioninaemia in a child with clinical and neuroradiological findings of Leigh disease
Authors: Di Rocco M. , Caruso U. , Moroni I. , Lupino S. , Lamantea E. , Fantasia A. R. , Borrone C. , Gibson K. M.
Published: December 2002

We report on a child with a clinical and neuroradiological picture consistent with Leigh disease and an unusual association of isolated hypermethioninaemia and 3‐methylglutaconic aciduria. A low‐methionine diet normalized both plasma methionine and urine 3‐methylglutaconic acid; a methionine‐loading test led to significant increase of both metabolites. In the skin fibroblasts the activity of 3‐methylglutaconyl‐CoA hydratase was essentially normal. No explanation of this uncommon association of hypermethioninaemia and glutaconic aciduria is available. The possibility of a common transporter for 3‐methylglutaconic acid and methionine is an attractive hypothesis.
X‐linked cardioskeletal myopathy and neutropenia (Barth syndrome) (MIM 302060)
Authors: Barth P. G. , Wanders R. J. A. , Vreken P. , Janssen E. A. M. , Lam J. , Baas F.
Published: December 2002

X‐linked cardioskeletal myopathy, neutropenia and abnormal mitochondria (MIM 302060) (synonyms: Barth syndrome, 3‐methylglutaconic aciduria type II, endocardial fibroelastosis type 2) has been reported in patients and families from Europe, North America and Australia. Previous studies characterized the main components of the disease: dilated cardiomyopathy, skeletal myopathy, neutropenia, 3‐methylglutaconic aciduria and diminished statural growth. Respiratory chain impairments have been found in several studies, without pinpointing a single enzyme complex. 3‐Methylglutaconic aciduria is shared with several other disorders that affect the respiratory chain. Previous studies excluded a block in the major pathway of leucine catabolism. We performed leucine loading, accompanied by fasting, in patients and observed a significant rise of 3‐methylglutaconic acid and 3‐methylglutaric acid. Taken together with the absence of an enzymatic block in the major leucine catabolic route, the possibility remains that the increased basal excretion of 3‐methylglutaconic acid and other products of branched‐chain amino acids is the result of overload of this pathway or — more likely — mitochondrial leakage. Linkage studies have localized the gene to the Xq28 region. The associated tafazzin gene (TAZ), has been fully characterized recently, and mutations located in conserved regions have been reported. Carrier detection and prenatal diagnosis have now become possible through mutation analysis. Sequence homology of the TAZ gene to a highly conserved superclass of acyltransferases (Neuwald's hypothesis) predicts a glycerophospholipid as the missing end product. This points to the (lipid) structure of the inner mitochondrial membrane as a promising new area of research.
Na+, K+-ATPase Isozyme Diversity; Comparative Biochemistry and Physiological Implications of Novel Functional Interactions
Authors: Mobasheri Ali , Avila Julio , Cózar-Castellano Irene , Brownleader Michael D. , Trevan Michael , Francis Martin J.O. , Lamb Joseph F. , Martín-Vasallo Pablo
Published: December 2002

Na+, K+-ATPase is ubiquitously expressed in the plasma membrane ofall animal cells where it serves as the principal regulator of intracellularion homeostasis. Na+, K+-ATPase is responsible for generating andmaintaining transmembrane ionic gradients that are of vital importance forcellular function and subservient activities such as volume regulation, pHmaintenance, and generation of action potentials and secondary activetransport. The diversity of Na+, K+-ATPase subunit isoforms andtheir complex spatial and temporal patterns of cellular expression suggestthat Na+, K+-ATPase isozymes perform specialized physiologicalfunctions. Recent studies have shown that the α subunit isoformspossess considerably different kinetic properties and modes of regulationand the β subunit isoforms modulate the activity, expression and plasmamembrane targeting of Na+, K+-ATPase isozymes. This review focuseson recent developments in Na+, K+-ATPase research, and in particular reportsof expression of isoforms in various tissues and experiments aimed atelucidating the intrinsic structural features of isoforms important forNa+, K+-ATPase function.
A non‐glycosylated and functionally deficient mutant (N215H) of the sphingolipid activator protein B (SAP‐B) in a novel case of metachromatic leukodystrophy (MLD)
Authors: Wrobe D. , Henseler M. , Huettler S. , Pascual Pascual S. I. , Chabas A. , Sandhoff K.
Published: December 2002

The lysosomal degradation of sphingolipids with short oligosaccharide chains depends on small glycosylated non‐enzymatic sphingolipid activator proteins (SAPs, saposins). Four of the five known SAPs, SAP‐A, ‐B, ‐C and ‐D, are derived by proteolytic processing from a common precursor protein (SAP‐precursor) that is encoded by a gene on chromosome 10 consisting of 15 exons and 14 introns. SAP‐B is a non‐specific glycolipid binding protein that stimulates in vitro the hydrolysis of about 20 glycolipids by different enzymes. In vivo SAP‐B stimulates in particular the degradation of sulphatides by arylsulphatase A. So far, four different point mutations have been identified on the SAP‐B domain of the SAP‐precursor gene. The mutations result in a loss of mature SAP‐B, causing the lysosomal accumulation of sulphatides and other sphingolipids, resulting in variant forms of metachromatic leukodystrophy (MLD). Here we report on a patient with SAP‐B deficiency that is caused by a new homoallelic point mutation that has been identified by mRNA and DNA analysis. A 643A>C transversion results in the exchange of asparagine 215 to histidine and eliminates the single glycosylation site of SAP‐B. Metabolic labelling experiments showed that the mutation had no effect on the intracellular transport of the encoded precursor to the acidic compartments and its maturation in the patient's cells. All four SAPs (SAP‐A to SAP‐D) were detectable by immunochemical methods. SAP‐B in the patient's cells was found to be slightly less stable than the protein in normal cells and corresponded in size to the deglycosylated form of the wild‐type SAP‐B. Feeding studies with non‐glycosylated SAP‐precursor, generating non‐glycosylated SAP‐B, showed that the loss of the carbohydrate chain reduced the intracellular activity of the protein significantly. The additional structural change of the patient's SAP‐B, caused by the change of amino acid 215 from asparagine to histidine, presumably resulted in an almost completely inactive protein.
Carnitine palmitoyltransferase I deficiency in neonate identified by dried blood spot free carnitine and acylcarnitine profile
Authors: Sim K. G. , Wiley V. , Carpenter K. , Wilcken B.
Published: December 2002

A neonate at risk for hepatic carnitine palmitoyltransferase I (L‐CPT I) deficiency was investigated from birth. The free carnitine and acylcarnitine profile in dried whole blood filter paper samples collected at ages 1 and 4 days showed a markedly elevated concentration of free carnitine (141 and 142 μmol/L, respectively), normal concentrations of acetyl‐ and propionylcarnitine, with the near absence of all other species. The diagnosis was confirmed by in vitro fatty acid oxidation screening assays and enzyme assay in cultured skin fibroblasts. Retrospective study of the newborn whole blood sample of the index case showed a similar profile (free carnitine 181 μmol/L). The newborn population distribution of free carnitine (n=143981) showed that only three samples had free carnitine >140 μmol/L (>99.9th centile), two were from L‐CPT I‐deficient neonates and one from a baby with sepsis. While there are other conditions that can cause elevated concentrations of free carnitine, an isolated elevation of free carnitine only in an apparently healthy term neonate warrants further investigation to exclude L‐CPT I deficiency.
Novel mutations cause biotinidase deficiency in Turkish children
Authors: Pomponio R. J. , Coskun T. , Demirkol M. , Tokatli A. , Ozalp I. , Hüner G. , Baykal T. , Wolf B.
Published: December 2002

Mutation analysis was performed on DNA from 31 Turkish children with profound biotinidase deficiency who were symptomatic or ascertained by newborn screening. The 98G:del7ins3 mutation is common in clinically ascertained children in both the United States and Turkish populations, but a unique common mutation, R79C, is found only in the Turkish children identified both clinically and by newborn screening. Another frequently occurring mutation, T532M, is only observed in the Turkish newborn screening group. There are four other less frequent novel mutations identified in the Turkish population. Interestingly, the Q456H and the A171T:D444H double mutation, which are the most common mutations found in the US newborn screening population and have not been observed in symptomatic children, do occur in clinically ascertained children in the Turkish population, although the double mutation may be associated with milder and/or later‐onset symptoms.
Influence of dose and age on the response of the allopurinol test for ornithine carbamoyltransferase deficiency in control infants
Authors: Riudor E. , Arranz J. A. , Rodés M. , Rubio V. , Sentís M. , Burlina A. B.
Published: December 2002

Measurement of urinary orotidine and orotic acid after an oral allopurinol challenge is an important diagnostic test for ornithine carbamoyltransferase deficiency that is sometimes used in infants (<1 year of age), although there is little information on normal test results in this age group. We found higher orotidine excretion in normal infants than in older children given the test, whereas orotate excretion was similar in both groups. The increased orotidine excretion appears to be due to the use in the infants of higher allopurinol doses per kilogram of body weight than in the children. The normalized‐dose dependency of the orotidine response extends even to adult age. Thus, dose‐normalized responses should be used in the test and there is no need for careful age‐matching of the controls.
Pulmonary hypertension associated with nonketotic hyperglycinaemia
Authors: Çataltepe S. , van Marter L. J. , Kozakewich H. , Wessel D. L. , Lee P. J. , Levy H. L.
Published: December 2002

Nonketotic hyperglycinaemia (NKH) is an autosomal recessive disorder characterized by defective glycine degradation by the mitochondrial glycine cleavage system. The clinical features include lethargy, hypotonia, apnoea, seizures and severe psychomotor retardation, all attributed to the accumulation of glycine in the nervous system. Pulmonary hypertension (PHN) has not been reported in NKH. We describe four patients with NKH who had PHN in addition to the characteristic manifestations of NKH. This newly recognized association might provide additional insight into the underlying pathophysiology of PHN.
The adult and adolescent clinic for inborn errors of metabolism
Authors: Brenton D. P.
Published: December 2002

Adolescent and adult clinics for patients with inborn metabolic errors are needed first to provide care to patients who develop distinctive problems as their different disorders impinge on education, career and family life. The selection of patients in this article illustrates the range of the problems. Fundamental research will be a shared interest with paediatricians and others, but outcomes of care and treatment in young adults and in patients in middle life must be a special concern of adult clinics. It is essential to gather that information. The best model is probably an outpatient service for all ages in a single centre with paediatricians and adult physicians contributing and sharing access to dietary and laboratory services. Such a model would be best for generating the meetings, case discussions and initiatives that contribute to a thriving and energetic unit. Clearly identified centres in each country would be an effective means of acquiring the information on the adult follow‐up of these uncommon disorders.
Glucose transporters: Structure, function and consequences of deficiency
Authors: Brown G. K.
Published: December 2002

There are two mechanisms for glucose transport across cell membranes. In the intestine and renal proximal tubule, glucose is transported against a concentration gradient by a secondary active transport mechanism in which glucose is cotransported with sodium ions. In all other cells, glucose transport is mediated by one or more of the members of the closely related GLUT family of glucose transporters. The pattern of expression of the GLUT transporters in different tissues is related to the different roles of glucose metabolism in different tissues. Primary defects in glucose transport all appear to be extremely rare and not all possible deficiencies have been identified. Deficiency of the secondary active sodium/glucose transporters result in glucose/galactose malabsorption or congenital renal glycosuriäGLUT1 deficiency produces a seizure disorder with low glucose concentration in cerebrospinal fluid and GLUT2 deficiency is the basis of the Fanconi–Bickel syndrome, which resembles type I glycogen storage disease.
Disorders related to peroxisomal membranes
Authors: Gärtner J.
Published: December 2002

The peroxisome is a ubiquitous, subcellular organelle participating in a diverse array of metabolic pathways. The peroxisomal membrane and its components play a key role in organelle assembly and functions. Disorders related to peroxisomal membranes are the peroxisome biogenesis disorders and X‐linked adrenoleukodystrophy. Identification and functional characterization of these disease genes is proceeding at rapid pace helped immeasurably by work in various yeast model systems. The ultimate goal is to elucidate how the encoded proteins interact to produce apparently normal and functioning peroxisomes. The achievement of this goal will lead to a better understanding of disease pathogenesis and hopefully open therapeutic options.
Peripheral and autonomic nervous system involvement in chronic GM2‐gangliosidosis
Authors: Salman M. S. , Clarke J. T. R. , Midroni G. , Waxman M. B.
Published: December 2002

GM2‐gangliosidosis (McKusick 268800 and 272800) is a rare hereditary, progressive disorder of ganglioside metabolism caused by deficiency of lysosomal β‐hexosaminidase (EC 3.2.1.52) activity. It is characterized by severe central nervous system involvement. Involvement of the peripheral and autonomic nervous system has been suspected but rarely documented in published case reports in the chronic form of the disease. Four patients, aged 24–29 years, with chronic GM2‐gangliosidosis were examined prospectively for evidence of peripheral and autonomic nervous system dysfunction. All had nerve conduction studies, sympathetic skin responses and cardiac monitoring during the head tilt‐table test. Three patients had objective evidence of autonomic dysfunction with abnormal sympathetic nervous skin responses and axonal sensorimotor polyneuropathy. None of the patients had evidence of significant cardiovascular autonomic dysfunction on the head tilt‐table test. The peripheral and autonomic nervous system may be involved in patients with chronic GM2‐gangliosidosis. In some cases, this may be clinically significant. On the other hand, cardiovascular autonomic instability is apparently not a significant problem in young adult patients with the disease.
Phenylalanine supplementation improves the phenylalanine profile in tyrosinaemia
Authors: Wilson C. J. , Van Wyk K. G. , Leonard J. V. , Clayton P. T.
Published: December 2002

Tyrosinaemia types I and II are caused by enzyme deficiencies in the tyrosine catabolism pathway. Successful treatment is possible with the novel enzyme inhibitor NTBC in tyrosinaemia type I and with dietary tyrosine and phenylalanine restriction in both conditions. This is achieved with a low natural protein intake and a supplementary amino acid formula that is phenylalanine‐ and tyrosine‐free. Patients on this regimen had been noted, periodically, to have very low plasma phenylalanine concentrations (<20 μmol/L). The tyrosine and phenylalanine profiles in six patients were measured. Five of the six patients had very low concentrations of phenylalanine during the later half of the day. The response to phenylalanine supplementation was assessed and supplementing the diet with phenylalanine 30–40 mg/kg per day resulted in normal concentrations throughout the day. Possible complications of hypophenylalaninaemia and potential preventive treatment strategies are discussed. Further studies are needed to investigate the longer‐term clinical and biochemical consequences of phenylalanine supplementation.
Sensitivity and specificity of free and total glutaric acid and 3‐hydroxyglutaric acid measurements by stable‐isotope dilution assays for the diagnosis of glutaric aciduria type I
Authors: Baric I. , Wagner L. , Feyh P. , Liesert M. , Buckel W. , Hoffmann G. F.
Published: December 2002

Glutaric aciduria type I (GA I) is a recessive disorder caused by a deficiency of glutaryl‐CoA dehydrogenase (GCDH). The biochemical hallmark of the disease is the accumulation of glutaric acid and, to a lesser degree, of 3‐hydroxyglutaric acid and glutaconic acid in body fluids and tissues. A substantial number of patients show only slightly, intermittently elevated or even normal urinary excretion of glutaric acid, which makes early diagnosis and treatment to prevent the severe neurological sequelae difficult. Furthermore, elevated urinary excretion of glutaric acid can also be found in a number of other disease states, mostly related to mitochondrial dysfunction. Stable‐isotope dilution assays were designed for both glutaric acid and 3‐hydroxyglutaric acid and their diagnostic sensitivity and specificity were evaluated. Control ranges of glutaric acid in urine were 1.1–9.7mmol/mol creatinine before and 4.1–32 after hydrolysis. The respective values of 3‐hydroxyglutaric acid were 1.4–8.0 and 2.6–11.7mmol/mol creatinine. For other body fluids, control ranges in μmol/L were: for glutaric acid 0.55–2.9 (plasma), 0.18–0.63 (cerebrospinal fluid) and 0.19–0.7 (amniotic fluid); and for 3‐hydroxyglutaric acid, 0.2–1.36 (plasma), <0.2 (cerebrospinal fluid) and 0.22–0.41 (amniotic fluid). Twenty‐five patients with GCDH deficiency were studied. Low excretors (12 patients) were defined by a urinary glutaric acid below 100mmol/mol creatinine down into the normal range, while high excretors (13 patients) had glutaric acid excretions well above this value. With and without hydrolysis there was an overlap of glutaric acid values between patients and controls. Diagnostic sensitivity and specificity of 100% could only be achieved by the quantitative determination of 3‐hydroxyglutaric acid with the newly developed stable‐isotope dilution assay, allowing an accurate diagnosis of all patients, regardless of the amount of glutaric acid excreted in urine.
Disorders related to mitochondrial membranes: Pathology of the respiratory chain and neurodegeneration
Authors: Di Donato S.
Published: December 2002

Faulty oxidative phosphorylation (OXPHOS) is observed in a number of mitochondrial disorders, and may be associated with single or multiple defects of the five complexes of the respiratory chain. From the genetic standpoint, the respiratory chain is unique as it is formed by means of the complementation of two separate genetic systems: the nuclear genome and the mitochondrial genome. The nuclear genome encodes most of the protein subunits of the respiratory complexes and most of the mtDNA replication and expression systems, whereas the mitochondrial genome encodes only 13 OXPHOS subunits and some RNA components of the mitochondrial translation apparatus. Accordingly, mitochondrial disorders due to defects in oxidative phosphorylation include both Mendelian‐inherited and cytoplasmic‐inherited diseases. Although our knowledge of these diseases has grown at an impressive rate in the past few years, it is worth noting that, as a result of complementation in the respiratory chain of nuclear‐encoded and mitochondrially‐encoded polypeptides, it is often difficult to establish a precise relationship between genomic mutations and biochemical phenotypes, or to distinguish pathogenic mutations from polymorphic variants in gene sequences.

This review deals with human diseases due to mutations of the structural components of the respiratory chain, particularly focusing on the recently identified disorders caused either by mutations in nuclear genes encoding subunits of the subcomplexes or by mutations in nuclear genes affecting the functional efficiency, homeostasis, and assembly of respiratory chain subcomplexes. To better focus on OXPHOS genotype–phenotype correlations, mutations of the mtDNA‐encoded structural genes are also discussed.
UDPgalactose epimerase in lens and fibroblasts: Activity expression in patients with cataracts and mental retardation
Authors: Shin Y. S. , Korenke G.‐C. , Huppke P. , Knerr I. , Podskarbi T.
Published: December 2002

Galactosaemia due to UDPgalactose 4‐epimerase (GALE; EC 5.1.3.2) deficiency is known to be a relatively rare autosomal recessive disorder. Up to now it has been divided into two forms, an extremely rare generalized form with a severe clinical course and a benign peripheral form that is confined to red cells (Gitzelmann 1972; Holton et al 1981; Sardharwalla et al 1988; Segal and Berry 1995). There are, however, recent descriptions of patients with the peripheral form of GALE deficiency developing juvenile cataracts or mental retardation (Endres and Shin 1990; Schulpis et al 1993; Alano et al 1998). We report here expression of the GALE enzyme in various tissues, especially in the lens, and different clinical pictures in patients we have diagnosed during the last 5 years.
A relational perspective on PTSD in early childhood
Authors: Scheeringa Michael S. , Zeanah Charles H.
Published: December 2002

This paper describes the clinical and research evidence for the importance of the relational context of posttraumatic stress disorder in young children. We review 17 studies that simultaneously assessed parental and child functioning following trauma. In many studies, despite limitations, an association between undesirable parental/family variables and maladaptive child outcomes has been consistently found. We present a model of the parental/family variables as moderators and vicarious traumatic agents for symptoms in young children. Also, a Compound Model is proposed, with three distinctive patterns of the parent—child relationship that impact on posttraumatic symptomatology in young children. Implications for clinical practice and research directions are discussed.
Genetic analysis of iron citrate toxicity in yeast: Implications for mammalian iron homeostasis
Authors: Chen Opal S. , Hemenway Shawn , Kaplan Jerry
Published: December 2002

Deletion of the yeast homologue of frataxin,
YFH1
, results in mitochondrial iron accumulation and respiratory deficiency (petite formation). We used a genetic screen to identify mutants that modify iron-associated defects in respiratory activity in Δ
yfh1
cells. A deletion in the peroxisomal citrate synthase
CIT2
in Δ
yfh1
cells decreased the rate of petite formation. Conversely, overexpression of
CIT2
in Δ
yfh1
cells increased the rate of respiratory loss. Citrate toxicity in Δ
yfh1
cells was dependent on iron but was independent of mitochondrial respiration. Citrate toxicity was not restricted to iron-laden mitochondria but also occurred when iron accumulated in cytosol because of impaired vacuolar iron storage. These results suggest that high levels of citrate may promote iron-mediated tissue damage.
Discovery of lipid peroxidation products formed
in vivo
with a substituted tetrahydrofuran ring (isofurans) that are favored by increased oxygen tension
Authors: Fessel Joshua P. , Porter Ned A. , Moore Kevin P. , Sheller James R. , Roberts L. Jackson
Published: December 2002

Free radicals have been implicated in the pathogenesis of an increasing number of diseases. Lipids, which undergo peroxidation, are major targets of free radical attack. We report the discovery of a pathway of lipid peroxidation that forms a series of isomers
in vivo
that are characterized by a substituted tetrahydrofuran ring structure, termed isofurans (IsoFs). We have proposed two distinct pathways by which IsoFs can be formed based on
18
O
2
and H
2
18
O labeling studies. Measurement of F
2
-isoprostanes (IsoPs), prostaglandin F
2
-like compounds formed nonenzymatically as products of lipid peroxidation, is considered one of the most reliable approaches for assessing oxidative stress status
in vivo
. However, one limitation with this approach is that the formation of IsoPs becomes limited at high oxygen tension. In contrast, the formation of IsoFs becomes increasingly favored as oxygen tension increases. IsoFs are present at readily detectable levels in normal fluids and tissues, and levels increase dramatically in CCl
4
-treated rats, an animal model of oxidant injury. The ratio of IsoFs to IsoPs in major organs varies according to normal steady-state tissue oxygenation. In addition, IsoFs show a marked increase early in the course of hyperoxia-induced lung injury, whereas IsoPs do not significantly increase. We propose that combined measurement of IsoFs and IsoPs should provide a more reliable index of oxidant stress severity than quantification of either alone because of the opposing modulation of the two pathways by oxygen tension, which can vary widely in different organs and disease states.
The fibronectin-binding integrins α5β1 and αvβ3 differentially modulate RhoA–GTP loading, organization of cell matrix adhesions, and fibronectin fibrillogenesis
Authors: Danen Erik H.J. , Sonneveld Petra , Brakebusch Cord , Fässler Reinhard , Sonnenberg Arnoud
Published: December 2002

We have studied the formation of different types of cell matrix adhesions in cells that bind to fibronectin via either α5β1 or αvβ3. In both cases, cell adhesion to fibronectin leads to a rapid decrease in RhoA activity. However, α5β1 but not αvβ3 supports high levels of RhoA activity at later stages of cell spreading, which are associated with a translocation of focal contacts to peripheral cell protrusions, recruitment of tensin into fibrillar adhesions, and fibronectin fibrillogenesis. Expression of an activated mutant of RhoA stimulates αvβ3-mediated fibrillogenesis. Despite the fact that α5β1-mediated adhesion to the central cell-binding domain of fibronectin supports activation of RhoA, other regions of fibronectin are required for the development of α5β1-mediated but not αvβ3-mediated focal contacts. Using chimeras of β1 and β3 subunits, we find that the extracellular domain of β1 controls RhoA activity. By expressing both β1 and β3 at high levels, we show that β1-mediated control of the levels of β3 is important for the distribution of focal contacts. Our findings demonstrate that the pattern of fibronectin receptors expressed on a cell dictates the ability of fibronectin to stimulate RhoA-mediated organization of cell matrix adhesions.
Activation of nuclear factor-κB is necessary for myotrophin-induced cardiac hypertrophy
Authors: Gupta Sudhiranjan , Purcell Nicole H. , Lin Anning , Sen Subha
Published: December 2002

The transcription factor nuclear factor-κB (NF-κB) regulates expression of a variety of genes involved in immune responses, inflammation, proliferation, and programmed cell death (apoptosis). Here, we show that in rat neonatal ventricular cardiomyocytes, activation of NF-κB is involved in the hypertrophic response induced by myotrophin, a hypertrophic activator identified from spontaneously hypertensive rat heart and cardiomyopathic human hearts. Myotrophin treatment stimulated NF-κB nuclear translocation and transcriptional activity, accompanied by IκB-α phosphorylation and degradation. Consistently, myotrophin-induced NF-κB activation was enhanced by wild-type IκB kinase (IKK) β and abolished by the dominant-negative IKKβ or a general PKC inhibitor, calphostin C. Importantly, myotrophin-induced expression of two hypertrophic genes (atrial natriuretic factor [ANF] and c-myc) and also enhanced protein synthesis were partially inhibited by a potent NF-κB inhibitor, pyrrolidine dithio-carbamate (PDTC), and calphostin C. Expression of the dominant-negative form of IκB-α or IKKβ also partially inhibited the transcriptional activity of ANF induced by myotrophin. These findings suggest that the PKC–IKK–NF-κB pathway may play a critical role in mediating the myotrophin-induced hypertrophic response in cardiomyocytes.
Mutual Help Groups, Perceived Status Benefits, and Well‐Being: A Test with Adult Children of Alcoholics with Personal Substance Abuse Problems
Authors: Kingree J. B. , Thompson Martie
Published: December 2002

A field experiment was conducted to examine the potential effects of mutual help group participation on perceived status benefits, depression, and substance use among adult children of alcoholics (ACOAs) with personal substance abuse problems. Participants were randomly assigned to attend either ACOA‐specific mutual help group meetings or substance abuse education classes during the initial month that they were enrolled in a residential treatment program for low‐income substance abusers. Analyses were based on assessments made at baseline, a 1‐month posttest, and a 6‐month follow‐up. Results indicated that participation in the mutual help group promoted perceived status benefits, which in turn led to reductions in depression and substance use. These findings have clear implications for consumers of ACOA groups and can inform research on the social psychological underpinnings of different types of mutual help groups.
Oligosaccharide excretion in adult Gaucher disease
Authors: de Jong J. G. N. , Aerts J. M. F. G. , van Weely S. , Hollak C. E. M. , van Pelt J. , van Woerkom L. M. J. , Liebrand‐van Sambeek M. L. F. , Wevers R. A.
Published: December 2002

Gaucher disease is a lysosomal storage disease characterized by storage of glucocerebroside due to lysosomal glucocerebrosidase deficiency. Increased urinary excretion of sialyloligosaccharides and mannosylglycoasparagines has been described for two patients with the infantile form of the disease, probably as a consequence of obstruction of lysosomal functioning due to the glycolipid accumulation in lysosomes. By thin‐layer chromatography, we found increased urinary oligosaccharide excretion in a series of adult non‐neuronopathic patients. Oligosaccharide patterns were comparable between patients and also with the pattern observed in infantile Gaucher disease. Composition was analysed by methanolysis and gas chromatography. Mannose and N‐acetylglucosamine are the main carbohydrates in all oligosaccharide bands. A statistically significant correlation was found between oligosaccharide excretion and the severity of the disease expressed as severity score index. Patients treated with enzyme replacement therapy showed a reduction up to 65% of the original oligosaccharide excretion after 1 year of treatment, comparable with the reduction in spleen volume.
Phenylketonuria in Italy: Distinct distribution pattern of three mutations of the phenylalanine hydroxylase gene
Authors: Guzzetta V. , Bonapace G. , Dianzani I. , Parenti G. , Lecora M. , Giannattasio S. , Concolino D. , Strisciuglio P. , Sebastio G. , Andria G.
Published: December 2002

Phenylketonuria (PKU) is an autosomal recessive disease caused by the deficiency of a liver‐specific enzyme, phenylalanine hydroxylase (PAH). The pattern of PAH mutations in Mediterranean populations appears to be different from that observed in northern Europe and Asia. Our aim was to study the molecular basis of PKU in Campania and Calabria, two regions of southern Italy. We studied 99 unrelated alleles, detecting 75.8% of the mutations. Our results show that 57% of all the PKU alleles are caused by three different mutations: IVS10nt‐546, R261Q and L48S, which display significant differences in their relative distribution across Italy. A novel mutation, a G‐to‐T transversion at the codon 257 (G257C), was also identified. This mutation results in a Gly‐to‐Cys change in the catalytic domain of the protein.
A male child with the rumpshaker mutation, X‐linked spastic paraplegia/Pelizaeus‐Merzbacher disease and lysinuria
Authors: Naidu S. , Dlouhy S.R. , Geraghty M.T. , Hodes M.E.
Published: December 2002

A 3.5‐year‐old boy had intact cognition, delayed walking, progressive spastic paraparesis and congenital nystagmus. The mother denied family history of any neurological disorders, so an extensive work‐up was begun. Lysinuria, increased signal on cerebral T2‐weighted MRI imaging and the rumpshaker mutation (Ile186Thr) in his proteolipid protein gene, PLP, were found. When faced with these facts, the mother admitted that she was related to the family reported by Johnston and McKusick in 1962 and Kobayashi in 1994, in whom this mutation has been reported. This is the first report of an abnormal MRI scan in this family.
Molecular characterization of a unique patient with epimerase‐deficiency galactosaemia
Authors: Alano A. , Almashanu S. , Chinsky J. M. , Costeas P. , Blitzer M. G. , Wulfsberg E. A. , Cowan T. M.
Published: December 2002

Inherited deficiencies of UDP‐galactose 4‐epimerase (GALE) havebeen associated with two distinct phenotypes. The vast majority of North American patients are clinically asymptomatic, are identified through newborn screening programmes for classical galactosaemia, and are of African‐American descent. At least two symptomatic patients have been reported, one Pakistani and the other Asian Muslim, both with severe complications in the neonatal period and subsequent mental retardation. Through newborn screening, we have identified a GALE‐deficient patient who is of mixed Pakistani/caucasian ancestry. He was clinically well in the neonatal period on a lactose‐containing diet, and biochemical studies, including urine reducing sugars and galactitol, were consistent with a diagnosis of peripheral GALE deficiency. Although early developmental milestones were met normally, he now shows significant developmental delays in both motor and language skills. Mutational analysis revealed this patient to be a compound heterozygote at the GALE locus, with mutations N34S and L183P identified in the patient and confirmed in the parents. This report represents the first characterization of specific mutations ina GALE‐deficient patient in conjunction with biochemical and clinical pheno‐type, and facilitates further studies of the GALE enzyme and its role in the different clinical forms of epimerase‐deficiency galactosaemia.
In vivo measurement of ureagenesis with stable isotopes
Authors: Yudkoff M. , Daikhin Y. , Ye X. , Wilson J. M. , Batshaw M. L.
Published: December 2002

We have utilized stable isotopes to measure in vivo rates of urea‐genesis. In one testing procedure, 15NH4Cl was administered orally to con‐trols and to heterozygotes for ornithine transcarbamylase deficiency. Controls produced [15N]urea at a rate that was greater than that of symptomatic carriers, but indistinguishable from that of asymptomatic carriers. In contrast, both symptomatic and asymptomatic heterozygotes produced [5‐15N]glutamine more rapidly than the controls. Ureagenesis could also be measured by administering sodium [1‐13C]acetate to a healthy adult and measuring subsequent formation of [13C]urea. The latter approach involves the use of isotope ratio mass spectrometry to determine isotopic abundance. This technique is much more sensitive than gas chromatography–mass spectrometry for the measurement of isotopic label, a consideration that makes the method more suitable for the study of subjects in whom ureagenesis is severely compromised, for example the human male neonate with a near complete deficiency of ornithine transcarbamylase.
Amino acid and nucleotide sequences of human peroxisomal enoyl‐CoA hydratase : 3‐hydroxyacyl‐CoA dehydrogenase cDNA
Authors: Fukuda S. , Suzuki Y. , Shimozawa N. , Zhang Z. , Orii T. , Aoyama T. , Hashimoto T. , Kondo N.
Published: December 2002

Deficiency of enoyl‐CoA hydratase : 3‐hydroxyacyl‐CoA dehydrogenase (peroxisomal bifunctional enzyme), one of the enzymes of the peroxisomal β‐oxidation system, leads to clinical manifestations resembling Zellweger syndrome with hypotonia, psychomotor delay, hepatomegaly, typical facial appearance and accumulation of very long‐chain fatty acids. The nucleotide sequence of the human peroxisomal enoyl‐CoA hydratase : 3‐hydroxyacyl‐CoA dehydrogenase cDNA has been reported by Hoefler and colleagues; however, we have found some amino acid differences from our originally isolated cDNA. Contrary to the findings described in a previous paper, we report here the cDNA sequence of human peroxisomal enoyl‐CoA hydratase : 3‐hydroxyacyl‐CoA dehydrogenase in which there are 9 authenticated amino acid alterations.
Gene transfer of the uroporphyrinogen III synthase cDNA into haematopoietic progenitor cells in view of a future gene therapy in congenital erythropoietic porphyria
Authors: Mazurier F. , Moreau‐Gaudry F. , Salesse S. , Barbot C. , Ged C. , Reiffers J. , de Verneuil H.
Published: December 2002

Congenital erythropoietic porphyria (CEP) is an inherited metabolic disorder characterized by an overproduction and accumulation of porphyrins in bone marrow. This autosomal recessive disease results from a deficiency of uroporphyrinogen III synthase (UROIIIS), the fourth enzyme of the haem biosynthetic pathway. It is phenotypically heterogeneous: patients with mild disease have cutaneous involvement, while more severely affected patients are transfusion dependent. The cloning of UROIIIS cDNA and genomic DNA has allowed the molecular characterization of the genetic defect in a number of families. To date, 22 different mutations have been characterized. Allogeneic bone marrow transplantation is the only curative treatment available for the severe, transfusion‐dependent, cases. When bone marrow transplantation cannot be performed owing to the absence of a suitable donor, the autografting of genetically modified cells is an appealing alternative. The best approach to somatic gene therapy in this disease involves the use of recombinant retroviral vectors to transduce cells ex vivo, followed by autologous transplantation of the genetically modified cells. We investigated retroviral transfer in deficient human fibroblasts, immortalized lymphoblasts as well as bone marrow cells, and obtained a complete restoration of the enzymatic activity and full metabolic correction.

Using K562 cells, an erythroleukaemic cell line, the expression of the transgene remained stable during 3 months and during erythroid differentiation of the cells. Finally, a 1.6‐ to 1.9‐fold increase in enzyme activity compared to the endogenous level was found in normal CD34+ cells, a population of heterogeneous cells known to contain the progenitor/stem cells for long‐term expression. The future availability of a mouse model of the disease will permit ex vivo gene therapy experiments on the entire animal.