bluuebunny/crossref_metadata_2025 huggingface dataset:
When to investigate for purine and pyrimidine disorders. Introduction and review of clinical and laboratory indications
Authors: Simmonds H. A. , Duley J. A. , Fairbanks L. D. , McBride M. B.
Published: December 2002

When to suspect and thus investigate for inborn errors of purine and pyrimidine metabolism is a dilemma for even the most observant investigator. Often parents of affected children, or a history involving siblings, can provide valuable clues. The recognition of new purine and pyrimidine disorders requires skill and serendipity. But even identifying known disorders can prove difficult, since they cover a broad spectrum of illnesses, can have more than one symptom, or lead to early death. This problem is compounded by the fact that they are relatively recently described and therefore often little known, either in the clinic or laboratory. The considerable heterogeneity in clinical expression within families as well as between families means that asymptomatic homozygotes may not be recognized or can present at any time from early childhood through adolescence up to their eighth decade. Consequently, all siblings should be screened. These disorders should be suspected in any case of unexplained anaemia, failure to thrive, susceptibility to recurrent infection, or neurological deficits with no current diagnosis, including autism, cerebral palsy, delayed development, deafness, epilepsy, self‐mutilation, muscle weakness, the inability to walk or talk, and ‐ unusual in children and adolescents ‐ gout, sometimes with renal disease. Some disorders present with radiolucent kidney stones, in acute or chronic renal failure, alone or with any of the above, or as an intolerance/sensitivity to therapy (e.g. 5‐fluorouracil in malignancies or azathioprine immunosuppression in organ transplantation), often with life‐threatening consequences. Several parameters need to be evaluated to ensure correct diagnosis. Pitfalls which can mask diagnosis using only a single test are renal failure, blood transfusion, diet or drugs.
Decreased platelet membrane anisotropy in patients with adrenoleukodystrophy treated with erucic acid (22:1)‐rich triglycerides
Authors: Stöckler S. , Opper C. , Greinacher A. , Hunneman D. H. , Korenke G. C. , Unkrig C. J. , Hanefeld F.
Published: December 2002

Low platelet count and bleeding diathesis have been observed in patients with adrenoleukodystrophy (ALD) treated with erucic acid (22:1)‐rich triglycerides (‘Lorenzo's oil’). To investigate possible alterations of biophysical membrane properties, we measured platelet membrane anisotropy, which is inversely related to membrane fluidity, in 16 patients with and in 3 patients without treatment. In patients on treatment, platelet membrane anisotropy was significantly decreased. Additionally, we found increased platelet concentrations of 22:1 and compromised in vitro platelet aggregation response. The decrease of platelet membrane anisotropy is probably a main cause of bleeding diathesis. Long‐term haematological side‐effects must be considered in ALD patients treated with Lorenzo's oil.
Fatty acid oxidation in fibroblasts from patients with defects in β‐oxidation and in the respiratory chain
Authors: Venizelos N. , von Döbeln U. , Hagenfeldt L.
Published: December 2002

Fatty acid oxidation has been studied with the tritium release assay in cultured fibroblasts from patients with defects in β‐oxidation and in the mitochondrial respiratory chain. Cells from all patients with β‐oxidation defects and cells from 10 of 16 patients with respiratory chain defects showed an impairment of fatty acid oxidation. The result of the tritium release assay is not only dependent on the proper function of the β‐oxidation cycle but is also influenced by the reoxidation of reduced cofactors. The assay can thus be used to study the expression of respiratory chain defects in cultured fibroblasts.
Mutations among Italian mucopolysaccharidosis type I patients
Authors: Gatti R. , DiNatale P. , Villani G.R.D. , Filocamo M. , Muller V. , Guo X.‐H. , Nelson P.V. , Scott H.S. , Hopwood J. J.
Published: December 2002

A group of 27 Italian patients was screened for α‐L‐iduronidase mucopolysaccharidosis type I mutations. Mutations were found in 18 patients, with 28 alleles identified. The two most common mutations in northern Europeans (W402X and Q70X) accounted for 11% and 13% of the alleles, respectively. The R89Q mutation, uncommon in Europeans, was found only in one patient, accounting for 1 of 54 alleles (1.9%). The other mutations, P533R, A327P and G51D, accounted for 11%, 5.6% and 9.3% of the total alleles, respectively. Interestingly, the high frequency of the P533R mutation seems to be confined to Sicily and is higher than the 3% reported in a British/Australian study.
Varicella and varicella immunity in patients with lysinuric protein intolerance
Authors: Lukkarinen M. , Näntö‐Salonen K. , Ruuskanen O. , Lauteala T. , Säkö S. , Nuutinen M. , Simell O.
Published: December 2002

Two patients with lysinuric protein intolerance (LPI) had near‐fatal generalized varicella infection with severe interstitial pneumonitis, hepatitis, decreased platelet count, bleeding and hypoalbuminaemia. Active haemolysis resulted in anaemia and massive haemoglobinuria. Serum lactate dehydrogenase activity and ferritin concentration, which in patients with LPI in normal circumstances exceed the upper reference values 3‐fold to 10‐fold, increased to >10 000U/L and >10 000 µg/L, respectively. The patients were treated with fresh frozen plasma, red‐cell transfusions and intravenous acyclovir for 14 days, and recovered clinically in a month. Retrospectively, 3 of the 32 other known Finnish patients with LPI had had varicella infection that had been more severe than that in the other children in the family or in subjects in the neighbourhood and had led to hospital admission. Varicella antibodies were measured in 24 patients; 5 had no antibodies and 5 had very low antibody titres. Primary vaccination of three patients with living varicella vaccine increased antibody titres measurably in one patient. We suggest that patients with LPI who have no varicella zoster antibodies should be treated with acyclovir if exposed to varicella and should be (re)vaccinated against chickenpox.
The biochemical and molecular spectrum of ornithine transcarbamylase deficiency
Authors: Tuchman M. , Morizono H. , Rajagopal B. S. , Plante R. J. , Allewell N. M.
Published: December 2002

Ornithine transcarbamylase (OTCase) deficiency, the most commoninherited urea cycle disorder, is transmitted as an X‐linked trait. The clinical phenotype in affected males as well as heterozygous females shows a spectrum of severity ranging from neonatal hyperammonaemic coma to asymptomatic adults. The ornithine transcarbamylase enzyme is a trimer with three active sites per holoenzyme molecule, each of which is composed of an interdomain region of one polypeptide and a polar domain of the adjacent polypeptide. The OTC gene is located on the short arm of the X‐chromosome and one of the two alleles undergoes inactivation in female cells. Approximately 140 mutations have been found in families affected with OTCase deficiency, most having their own ‘private’ mutation. Large deletions of one exon or more are seen in approximately 7% of patients, small deletions or insertions are seen in about 9%, and the remaining mutations are single base substitutions. Approximately 15% of mutations affect RNA splicing sites. The recurrent mutations are distributed equally among CpG dinucleotide hot spots. Generally, mutations causing neonatal disease affect amino acid residues that are ‘buried’ in the interior of the enzyme, especially around the active site, while those associated with late onset and milder phenotypes tend to be located on the surface of the protein. Very few mutations have been found in the sequence of the leader peptide, proportionally much fewer than in the sequence of the mature enzyme. Only few of the mutations have been expressed in bacteria or mammalian cells for the study of their deleterious mechanisms. Examples of expressed mutations include R277W and R277Q associated with late‐onset disease, which markedly increase the Km for ornithine, shift the pH optimum to more alkaline and decrease the thermal stability of the purified mutant enzyme. R141Q (neonatal disease) disrupts the active site, whereas the purified R40H mutant has normal catalytic function and this mutation is likely to affect posttranslational processing such as mitochondrial targeting. It appears that most new mutations occur in male sperm and are then passed on to a transmitting heterozygous female. Uncommonly, mild mutations are transmitted by asymptomatic males to their daughters, subsequently resulting in clinical disease of males in future generations. The causes for variable expressivity of these mutations are currently unknown but are likely to involve a combination of environmental and genetic modifiers.
Inborn errors of pyrimidine degradation: Clinical, biochemical and molecular aspects
Authors: van Gennip A.H. , Abeling N.G.G.M. , Vreken P. , van Kuilenburg A.B.P.
Published: December 2002

The pyrimidines, uracil and thymine, are degraded in four steps. The first three steps of pyrimidine catabolism, controlled by enzymes shared by both pathways, result in the production of the neurotransmitter amino acid β‐alanine from uracil and the nonfunctional (R)‐(‐)‐β‐aminoisobutyrate from thymine. The fourth step is controlled by several aminotransferases, which have different affinities for β‐alanine, β‐aminoisobutyrate and GABA. Defects concerning the first three steps all lead to a reduced production of β‐alanine; defects of the transaminases involving the metabolism of β‐alanine and GABA lead to accumulation of these neurotransmitter substances. In addition, other metabolites will accumulate or be reduced depending on the specific enzyme defect. Analysis of the abnormal concentrations of these metabolites in the body fluids is essential for the detection of patients with pyrimidine degradation defects. Clinically these disorders are often overlooked because symptomatology is highly aspecific. The growth in our knowledge concerning inborn errors of pyrimidine degradation has emphasized the importance of the clinical awareness of these defects as a possible cause of neurological disease and a contraindication for treatment of cancer patients with certain pyrimidine analogues. The various defects are discussed and attention is paid to clinical, genetic and diagnostic aspects.
Regulation of the urea cycle enzyme genes in nitric oxide synthesis
Authors: Mori M. , Gotoh T. , Nagasaki A. , Takiguchi M. , Sonoki T.
Published: December 2002

Nitric oxide (NO) is synthesized from arginine by nitric‐oxide synthase (NOS), and citrulline that is generated can be recycled to arginine by argininosuccinate synthase (AS) and argininosuccinate lyase (AL). Rats were injected with bacterial lipopolysaccharide (LPS) and expression of the inducible isoform of NOS (iNOS), AS and AL was analysed. In RNA blot analysis, iNOS mRNA was induced by LPS in the lung, heart, liver and spleen, and less strongly in the skeletal muscle and testis. AS and AL mRNAs were induced in the lung and spleen. Kinetic studies showed that iNOS mRNA increased rapidly in both spleen and lung, reached a maximum 2–5 h after the treatment, and decreased thereafter. On the other hand, AS mRNA increased more slowly and reached a maximum in 6–12 h (by about 10‐fold in the spleen and 2‐fold in the lung). AL mRNA in the spleen and lung increased slowly and remained high upto 24 h. In immunohistochemical analysis, macrophages in the spleen that were negative for iNOS and AS before LPS treatment were strongly positive for both iNOS and AS after this treatment. As iNOS, AS and AL were co‐induced in rat tissues and cells, citrulline–arginine recycling seems to be important in NO synthesis under the conditions of stimulation.

Arginine is a common substrate of NOS and arginase. Rat peritoneal macrophages were cultured in the presence of LPS and expression of iNOS and liver‐type arginase (arginase I) was analysed. mRNAs for iNOS and arginase I were induced by LPS in a dose‐dependent manner. iNOS mRNA appeared 2 h after LPS treatment and increased up to a near‐maximum at 8–12 h. On the other hand, arginase I mRNA began to increase after 4 h with a lag time and reached a maximum at 12 h. Immunoblot analysis showed that iNOS and arginase I proteins were also induced. Induction of iNOS and arginase I mRNAs were also observed in LPS‐injected rats in vivo. Thus, arginase I appears to have an important role in downregulating NO synthesis in murine macrophages by decreasing the availability of arginine.

A cDNA for human arginase II, an arginase isozyme, was isolated. A polypeptide of 354 amino acid residues including the putative NH2‐terminal presequence for mitochondrial import was predicted. It was 59% identical with arginase I. mRNA for human arginase II was present in the kidney and other tissues but was not detected in the liver. Arginase II mRNA was co‐induced with iNOS mRNA in murine macrophage‐like RAW 264.7 cells by LPS. This induction was enhanced by dexamethasone and dibutyrul cAMP, and was prevented by interferon‐γ.

These results indicate that NO synthesis is regulated by arginine‐synthesizing and ‐degrading enzymes in a complicated manner.
Plasma chitotriosidase activity in Gaucher disease patients who have been treated either by bone marrow transplantation or by enzyme replacement therapy with alglucerase
Authors: Young E. , Chatterton C. , Vellodi A. , Winchester B.
Published: December 2002

A marked elevation in plasma chitotriosidase (chitinase) activity has recently been observed in patients with Gaucher disease (Hollak et al 1994). It has been suggested that this phenomenon may serve as a useful marker for the efficacy of treatment with enzyme replacement therapy. We report our findings on the comparison of plasma chitotriosidase levels in 8 patients treated with the modified human placental enzyme alglucerase and 8 patients treated by allogeneic bone marrow transplantation (BMT). Two years after transplantation the activity in the BMT patients had fallen by over 93% and has continued to fall. Now, 5‐12 years post‐BMT, 6 patients have normal levels of plasma chitotriosidase and 2 patients have activities slightly above the reference range. Patients have been treated with alglucerase for a considerably shorter time than the BMT patients. The chitotriosidase activities have fallen and are continuing to fall in 7 patients but at a slower rate than in the BMT group. In one patient there has been no appreciable change in activity over the last 6 months, which would suggest that she may be on too low a dosage.
Developing adenoviral‐mediated in vivo gene therapy for ornithine transcarbamylase deficiency
Authors: Raper S. E. , Wilson J. M. , Yudkoff M. , Robinson M. B. , Ye X. , Batshaw M. L.
Published: December 2002

There are a number of reasons for choosing ornithine transcarbamylase (OTC) deficiency as a candidate for gene therapy: the gene has been cloned; the disorder is relatively common; the current clinical outcome is poor; and there are authentic animal models. In considering the development of gene therapy for OTC deficiency, we focused on the use of in vivo gene therapy with an adenoviral vector. Using the partially OTC‐deficient sparse fur mouse we found transduction and expression could be achieved using an intravenous infusion of a recombinant adenovirus containing the OTC cDNA. The results were transient as a result of immune activation in response to the vector and vector‐transduced cells. By modifying the adenoviral construct, creating an E1 deletion–E2 temperature‐sensitive mutation, we blunted the cytotoxic T lymphocyte immune response and achieved correction of biochemical abnormalities for 2–3 months. We also found that transduction and expression following gene transfer occurred sufficiently rapidly to protect against acute hyperammonaemia within 24 h. Subsequent preclinical studies in mice and non‐human primates demonstrated that E1–E4‐deleted vectors had a substantially improved safety profile and similar efficacy. With this evidence of efficacy and safety of adenoviral vectors, we are embarking on a phase I trial of intravascular gene transfer using an E1–E4‐deleted vector in adults with partial OTC deficiency.
Peroxisomal localization of α‐oxidation in human liver
Authors: Casteels M. , Croes K. , Van Veldhoven P. P. , Mannaerts G. P.
Published: December 2002

It was found that α‐oxidation in rat liver is a peroxisomal process, consisting of an activation, a 2‐hydroxylation, and a reaction leading to the production of formate. α‐Oxidation of 3‐methyl‐substituted fatty acids was quantified by measuring the production of formate and CO2, and the production of a 2‐hydroxy‐3‐methylacyl‐CoA‐intermediate was demonstrated. We wanted to extend these findings to human liver, in view of the controversy over the subcellular localization of α‐oxidation in man.

In homogenates from human liver, rates of α‐oxidation were highest when measured in the presence of ATP, CoA, Mg2+, 2‐oxoglutarate, ascorbate and Fe2+. In subcellular fractions prepared by differential centrifugation and in fractions obtained after subfractionation of a peroxisome‐enriched fraction on a Percoll gradient, production of formate and of a 2‐hydroxy‐3‐methylacyl‐CoA intermediate coincided with the peroxisomal marker catalase. In broken fractions, production of CO2 was almost negligible as compared to formate production.

We conclude from our findings that in human liver, as in rat liver, α‐oxidation of 3‐methyl‐substituted fatty acids is a peroxisomal process, consisting of an activation reaction, a 2‐hydroxylation reaction and a reaction or reactions leading to the generation of formate as a primary product which is subsequently converted to CO2. Furthermore activation, 2‐hydroxylation and generation of formate appear to be coupled (see Casteels et al 1996). These data demonstrate that Refsum disease should indeed be classified as a peroxisomal disease.
Allergic disease as an association of steroid sulphatase deficiency
Authors: Sakura N. , Nishimura S. , Matsumoto T. , Ohsaki M. , Ogata T.
Published: December 2002

Ten of 31 patients with steroid sulphatase (STS) deficiency were found to have an allergic disease (bronchial asthma, allergic rhinitis, or atopic dermatitis). STS deficiency may predispose patients to allergic disease.
Adult psychosocial outcome in early‐treated phenylketonuria
Authors: Ris M. D. , Weber A. M. , Hunt M. M. , Berry H. K. , Williams S. E. , Leslie N.
Published: December 2002

Concerns about the psychosocial risk of adults with early‐treated phenylketonuria (ETPKU) are predicated on four sources of scientific data: (1) consistent documentation of increased behavioural risk in children with ETPKU; (2) recent evidence of neurocognitive impairment in adults with ETPKU; (3) reports of neuroimaging abnormalities in adults with ETPKU; and (4) preliminary evidence of increased rates of psychiatric disturbance in this population. We studied the psychosocial adjustment of 25 patients, aged 18 years and older, with ETPKU. On most pscyhosocial outcome measures, patients were indistinguishable from 15 sibling controls. However, on a self‐report inventory of psychiatric symptoms, 20% of the patients demonstrated significant morbidity. Psychosocial outcome of these patients was unrelated to concurrent or historical biological dietary disease factors, unlike neurocognitive outcome. A strong relationship was demonstrated, however, between neurocognitive measures and psychosocial morbidity. These findings indicate that a significant minority of patients with ETPKU develop psychosocial difficulties with multiple clinical elevations on a psychiatric inventory. However, most adults with ETPKU cope with the challenges of young adulthood with the same degree of success as their unaffected siblings. Neuropsychological surveillance during childhood and adolescence is important in identifying patients at risk for both neurocognitive and psychosocial morbidity.
Myotonic dystrophy: Molecular and cellular consequences of expanded DNA repeats are elusive
Authors: Strong P. N. , Brewster B. S.
Published: December 2002

The mutation in the myotonic dystrophy (DM) gene is an expansion in a triplet (CTG)n repeat in the 3′ untranslated region of a novel gene that partially encodes a serine‐threonine protein kinase (DMPK), with closest sequence homology to a small subgroup of protein kinases involved in the control of proliferation and cell shape. Expansion of the repeat correlates reasonably well with disease severity and offers a plausible molecular explanation for the previously contentious issue of anticipation. There is considerable heterogeneity in CTG expansion size in different tissues of affected individuals. The consensus of data from many laboratories indicates that DMPK mRNA is most probably downregulated as a consequence of the repeat expansion. Two polypeptides (68/78 kDa) have been shown to be absent in mouse knockout mutants and therefore can be considered as bona fide gene products. Previous data suggesting that 52‐55 kDa polypeptides were likely candidates, have been firmly ruled out at the same time. Further results from studies of knockout and overexpressing transgenic mice indicate that neither simple loss nor gain of DMPK expression is sufficient to account for the DM clinical phenotype. One of the most pressing questions now being addressed is how expansion of the CTG repeat within the DMPK gene affects gene expression, not only of DMPK, but of all genes at the 19q13.3 locus: is DMPK actually responsible for the clinical phenotype seen in DM? The identification of both immediate upstream and downstream human genes (59 and DMRHP, respectively) has been an important first step to answering these questions. Only when these matters have been dealt with can one reasonably expect to start to delineate the different metabolic and signalling pathways responsible for the diverse phenotypes that make up the complex clinical picture of DM.
The success of dietary protein restriction in alkaptonuria patients is age‐dependent
Authors: de Haas V. , Carbasius Weber E. C. , de Klerk J. B. C. , Bakker H. D. , Smit G. P. A. , Huijbers W. A. R. , Duran M. , Poll‐The B. T.
Published: December 2002

Alkaptonuria is characterized by an increased urinary excretion of homogentisic acid, pigmentation of cartilage and connective tissues, and ultimately the development of inflammatory arthropathy. Various diets low in protein have been designed to decrease homogentisic acid excretion and to prevent the ochronotic pigmentation and arthritic lesions. However, limited information is available on the long‐term beneficial effects of these diets. We reviewed the medical records of 16 patients aged 3–27 years (4>18 years) to ascertain the age of diagnosis, growth, development, social behaviour, signs of complications and longitudinal dietary compliance. The diagnosis of alkaptonuria was made at an average age of 1.4 years (2 months–4 years); following the diagnosis all patients were prescribed a diet with a protein content of 1.5 g/kg per day. All patients showed normal growth and development, and no major complications of the disease. Behavioural problems associated with poor dietary compliance emerged as the main problem. Dietary compliance decreased progressively with age. The effect of dietary protein restriction in homogentisic acid excretion was studied by fixing the amounts of protein in the diet at 1 g/kg per day and 3.5–5 g/kg per day during 8 days. Twelve patients, aged 4–27 years, participated in the investigation. Protein restriction resulted in a significantly lower excretion of homogentisic acid in the urine of children younger than 12 years (p<0.01), whereas this effect was less obvious for adolescent and adult patients. The results suggest that restriction of protein intake may have a beneficial effect on alkaptonuric children; but continuation of this regimen to older age seems questionable and not practical.
Mutant CuZn superoxide dismutase in motor neuron disease
Authors: Gurney M. E. , Liu R. , Althaus J. S. , Hall E. D. , Becker D. A.
Published: December 2002

CuZn superoxide dismutase (CuZn SOD) is one of several antioxidant enzymes that defend the cell against damage by oxygen free radicals. Mutations of the SOD1 gene encoding CuZn SOD are found in patients with familial amyotrophic lateral sclerosis (FALS), a progressive and fatal paralytic disease that is caused by the death of motor neurons in cortex, brainstem and spinal cord. The disease can be reproduced in transgenic mice by expression of mutant human CuZn SOD. Recent studies both in vitro and in vivo suggest that the effect of mutation is to enhance the generation of oxygen radicals by the mutant enzyme. Thus, mutation converts a protective, antioxidant enzyme into a destructive, prooxidant form that catalyses free radical damage to which motor neurons are selectively vulnerable. Recent studies of neuroprotective agents in the FALS model show that inhibition of oxidative mechanisms (copper chelation therapy, dietary antioxidants, and coexpression of bcl‐2) delays disease onset but does not extend disease duration. In contrast, inhibition of glutamatergic or apoptotic mechanisms (riluzole, gabapentin, and coexpression of an inhibitor of caspase‐1) has no effect on disease onset but extends survival by increasing the duration of symptomatic disease. Thus, neuroprotective agents differentially target the processes underlying disease initiation and propagation.
The metabolism of phytanic acid and pristanic acid in man: A review
Authors: Verhoeven N. M. , Wanders R. J. A. , Poll‐The B. T. , Saudubray J.‐M. , Jakobs C.
Published: December 2002

The branched‐chain fatty acid phytanic acid is a constituent of the diet, present in diary products, meat and fish. Degradation of this fatty acid in the human body is preceded by activation to phytanoyl‐CoA and starts withone cycle of α‐oxidation. Intermediates in this pathway are 2‐hydroxy‐phytanoyl‐CoA and pristanal; the product is pristanic acid. After activation, pristanic acid is degraded by peroxisomal β‐oxidation. Several disorders havebeen described in which phytanic acid accumulates, in some cases in combination with pristanic acid. In classical Refsum disease, the enzyme that converts phytanoyl‐CoA into 2‐hydroxyphytanoyl‐CoA – phytanoyl‐CoA hydroxylase – is deficient, resulting in highly elevated levels of phytanic acid in blood and tissues. Also in rhizomelic chondrodysplasia punctata, phytanic acid accumulates, owing to a deficiency in the peroxisomal import of proteins with a peroxisomal targeting sequence type 2. In patients affected with generalized peroxisomal disorders, degradation of both phytanic acid and pristanic acid is impaired owing to absence of functional peroxisomes. In bifunctional protein deficiency, the disturbed oxidation of pristanic acid results in elevated levels of this fatty acid and a secondary elevation of phytanic acid. In addition, several variant peroxisomal disorders with unknown aetiology have been described in which phytanic acid and/or pristanic acid accumulate. This review describes the discovery of phytanic acid and pristanic acid and the initial attempts to elucidate the origins and fates of these fatty acids. The current knowledge on the α‐oxidation and β‐oxidation of these branched‐chain fatty acids is summarized. The disorders in which phytanic acid and/or pristanic acid accumulate are described and some remarks are made on the pathogenic mechanisms of elevated levels of phytanic acid and pristanic acid.
Menkes disease: Underlying genetic defect and new diagnostic possibilities
Authors: Tümer Z. , Horn N.
Published: December 2002

Cloning of the gene defective in the X‐linked neurodegenerative disorder Menkes disease led to a cascade of new findings. Besides giving a better understanding of the intracellular copper homeostasis, these findings had important consequences from a clinical point of view. Today the underlying genetic defect has been described in several patients affected by one of the three hereditary disorders of copper metabolism: Menkes disease, occipital horn syndrome and Wilson disease. In this review we discuss mainly Menkes disease and the impact of the recent findings on the diagnosis of this disorder.
Identification of new medium‐chain acylcarnitines present in urine of a patient with medium‐chain acyl‐CoA dehydrogenase deficiency
Authors: Libert R. , Van Hoof F. , Thillaye M. , Vincent M.‐F. , Nassogne M.‐C. , Stroobant V. , de Hoffmann E. , Schanck A.
Published: December 2002

Previously undescribed medium‐chain acylcarnitines were identified in a urine sample from a patient with medium‐chain acyl‐CoA dehydrogenase deficiency. These are the 4‐methylvaleryl, 4‐ and 5‐methylhexanoyl, 6‐methyl‐heptanoyl‐, 6‐methyloctanoyl‐, 4,5‐dimethylhexanoyl‐ and 4,7‐decadienoyl‐carnitines. Their chemical structures were obtained by gas chromatography–mass spectrometry analysis of their fatty acid moieties as picolinyl esters.
Generalized peroxisomal disorder in male twins: Fatty acid composition of serum lipids and response to n−3 fatty acids
Authors: Søvik O. , Månsson J.‐E. , Bjørke Monsen A.‐L. , Jellum E. , Berge R. K.
Published: December 2002

Male, identical twins presented with hypotonia, hypoglycaemia, dysmorphic facies, feeding problems, discoloured stools, hepatomegaly, and nephrolithiasis. Elevated blood levels of very long‐chain fatty acids and bile acids suggested a peroxisomal disorder. Plasmalogen biosynthesis in cultured fibroblasts was reduced. Morphologically distinct peroxisomes were undetectable in liver. Twin 1 suffered from nephrocalcinosis and severe infection, and died at 18 months of age. Twin 2 was blind and physically severely retarded with epilepsy, but survived up to the age of 5 years. Studies of the fatty acid composition of serum lipids showed barely detectable values of eicosapentaenoic (EPA) and docosahexaenoic acid (DHA). During long‐term treatment with these n−3 fatty acids, started at age 10 months, the fatty acid profile of the serum lipids was improved or normalized. Since n−3 fatty acids are essential elements in normal development, notably of the nervous system, we suggest that treatment with EPA and DHA should be started as early as possible in general peroxisomal disorders.
Medium‐chain triglyceride loading test in carnitine–acylcarnitine translocase deficiency: Insights on treatment
Authors: Parini R. , Invernizzi F. , Menni F. , Garavaglia B. , Melotti D. , Rimoldi M. , Salera S. , Tosetto C. , Taroni F.
Published: December 2002

The results of a medium‐chain triglyceride loading test in a patient with severe carnitine–acylcarnitine translocase deficiency clearly demonstrated impaired in vivo utilization of medium‐chain triglycerides. The loading test was performed at the ages of 7 and 36 months. The diet was adjusted accordingly. The clinical course has been favourable and the child is now in very good condition at age 4 years. We conclude that the utilization of medium‐chain triglycerides is only partial in carnitine–acylcarnitine translocase deficiency and cannot reasonably be considered an optimal source of energy for these patients. Careful adjustment of dietetic treatment may help to improve prognosis.
Characterization of a Histidine Rich Cluster of Amino Acids in the Cytoplasmic Domain of the Na+/H+ Exchanger
Authors: Dibrov Pavel , Murtazina Rakhilya , Kinsella James , Fliegel Larry
Published: December 2002

We examined the function of a highly conserved Histidine rich sequence ofamino acids found in the carboxyl-terminal of the Na+/H+exchanger (NHE1). A fusion protein containing the sequenceHYGHHH (540–545) and the balance of the carboxyl terminalof the protein did not bind calcium but bound to an immobilizedmetal affinity column and could be used to partially purify theexchanger protein. Mutation of the sequence to either HYGAAA orHYGRRR did not affect activity of the intact protein. Mutationto HHHHHH did not affect proton activation of the Na+/H+exchanger or localization but caused a decreased maximal velocitysuggesting that this conserved sequence is important in maximalactivity of the Na+/H+ exchanger.
Fluorescent Properties of Firefly Luciferases and Their Complexes with Luciferin
Authors: Dementieva Ekaterina I. , Fedorchuk Elena A. , Brovko Lubov Yu. , Savitskii Alexander P. , Ugarova Natalya N.
Published: December 2002

Fluorescence of luciferases from Luciola mingrelica (single tryptophanresidue, Trp-419) and Photinus pyralis (two tryptophan residues, Trp-417,Trp-426) was studied. Analysis of quenching of tryptophan fluorescenceshowed that the tryptophan residue conserved in all luciferases is notaccessible for charged quenchers, which is explained by the presence ofpositively and negatively charged amino acid residues in the close vicinityto it. An effective energy transfer from tryptophan to luciferin wasobserved during quenching of tryptophan fluorescence of both luciferaseswith luciferin. From the data on the energy transfer, the distance betweenthe luciferin molecule and Trp-417 (419) in the luciferin–luciferasecomplex was calculated: 11–15 Å for P. pyralis and 12–17Å for L. mingrelica luciferases. The role of the conserved Trp residuein the catalysis is discussed.
Molecular characterization of methylmalonate semialdehyde dehydrogenase deficiency
Authors: Chambliss K. L. , Gray R. G. F. , Rylance G. , Pollitt R. J. , Gibson K. M.
Published: December 2002

Three patients have been reported with (putative) methylmalonic semialdehyde dehydrogenase (MMSDH) deficiency. The urine metabolic pattern was strikingly different in all, including β‐alanine, 3‐hydroxypropionic acid, both isomers of 3‐amino‐ and 3‐hydroxyisobutyric acids in one and 3‐hydroxyisobutyric and lactic acids in a second, and mild methylmalonic aciduria in a third patient. In an effort to clarify these disparate metabolite patterns, we completed the cDNA structure, and characterized the genomic structure of human MMSDH gene in order to undertake molecular analysis. Only the first patient had alterations in the MMSDH coding region, revealing homozygosity for a 1336G>A transversion, which leads to substitution of arginine for highly conserved glycine at amino acid 446. No abnormalities of the MMSDH cDNA were detected in the other patients. These data provide the first molecular characterization of an inborn error of metabolism specific to the L‐valine catabolic pathway.
Effects of ethanol and of alcohol dehydrogenase inhibitors on the reduction of N‐acetylaspartate levels of brain in mice in vivo: a search for substances that may have therapeutic value in the treatment of Canavan disease
Authors: Baslow M. H. , Suckow R. F. , Hungund B. L.
Published: December 2002

Hair analysis can be used as a screening tool in the diagnosis of genetic diseases. The scalp hair roots of 67 normal neonates and 39 neonates with glucose‐6‐phosphate dehydrogenase (G6PD) deficiency were analysed using Fourier transform infrared (FT‐IR) microspectroscopy to differentiate the stages of the hair growth cycle and to diagnose the genetic disorder on the basis of spectral differences. We have demonstrated that FT‐IR microspectroscopy is a rapid and effective noninvasive diagnostic method to differentiate scalp hair roots of normal neonates into the anagen, catagen or telogen phases of the hair growth cycle, using IR spectral differences within the 3000–2800cm−1 region and the IR peak area ratio of 2854 cm−1/2873 cm−1 or 1084 cm−1/amide II band (p<0.001). Moreover, G6PD‐deficient neonates could be accurately diagnosed from telogen phase hair roots owing to significant differences in IR peak area ratios of 2854 cm−1/2873 −1 or 1084 cm−1/amide II band compared to normal values in healthy neonates. The result suggests that the application of FT‐IR microspectroscopy may be capable not only of differentiating the hair growth cycle into anagen, categen or telogen phases but also of detecting G6PD deficiency. Hair root analysis promises to be a useful complement to serum and urine analysis in the diagnosis of genetic diseases.
Clinical significance of brain phenylalanine concentration assessed by in vivo proton magnetic resonance spectroscopy in phenylketonuria
Authors: Leuzzi V. , Bianchi M. C. , Tosetti M. , Carducci Cl. , Carducci Ca. , Antonozzi I.
Published: December 2002

Recent studies using in vivo proton magnetic resonance spectroscopy (1H MRS) have suggested that plasma phenylalanine (Phe) may not be a reliable indicator of brain Phe level in subjects with phenylketonuria (PKU). Interindividual variation in cerebral Phe can contribute to the phenotypic variability of the disease. We report the results of the direct assessment of brain Phe by 1H MRS in 10 off‐diet PKU patients (aged 15.5–30.5 years), 4 detected and treated early, 6 late. In a single patient, brain Phe was evaluated before and 15 days after diet discontinuation. FLAIR MRI and 1H MRS were performed in the same setting by a 1.5 T clinical MR scanner. MR images were scored according to the extent of the lobar white‐matter hyperintensity. Brain 1H MRS Phe signal (resonating at 7.36 ppm) was evaluated as a ratio to the creatine+phosphocreatine signal. Brain Phe was correlated with clinical, biochemical and MRI findings. Results were as follows. (1) An abnormal concentration of brain Phe was detected in all 10 PKU subjects (ranging from 0.030 to 0.074), associated with a wide interindividual variability of concurrent plasma Phe (ranging from 724 to 2800 μmol/L). (2) In late‐detected subjects, brain Phe concentration correlated with clinical phenotype better than did plasma Phe. The discrepancy between brain and plasma Phe was relevant from a clinical point of view in two cases: in one, a late‐detected patient with normal mental development, a high level of plasma Phe was associated with a relatively low concentration of brain Phe; in the other, a late‐detected subject with severe neurological impairment, a very high level of brain Phe was associated with plasma Phe compatible with the diagnosis of mild PKU. (3) White‐matter alterations were detected in all patients. FLAIR MRI sequences disclosed an involvement of optic chiasma and tracts in 7 subjects. No correlation was found between white‐matter alterations and concurrent brain Phe concentrations. (4) In the only case assessed under different intake of Phe, the relevant increase of brain Phe paralleled the concurrent increase of plasma Phe, showing that 1H MRS can be a useful tool in evaluating the individual vulnerability of PKU patients to different values of plasma Phe.
Malonic aciduria in Maltese dogs: Normal methylmalonic acid concentrations and malonyl‐CoA decarboxylase activity in fibroblasts
Authors: O'Brien D. P. , Barshop B. A. , Faunt K. K. , Johnson G. C. , Gibson K. M. , Shelton G. D.
Published: December 2002

A family of Maltese dogs with malonic aciduria is reported. The propositus presented at 3 years of age with episodes of seizures and stupor with hypoglycaemia, acidosis, and ketonuria. Urinary organic acid assays showed elevated malonic acid without elevation of methylmalonic acid. Cultured fibroblasts had normal malonyl‐CoA decarboxylase activity. Treatment with frequent feedings of a low‐fat diet high in medium‐chain triglycerides resulted in normalization of clinical signs and a resolution of the malonic aciduria. Two full siblings of the propositus had died at a young age of undiagnosed metabolic and neurological disease. Urine organic acid assays were performed on other family members. A half‐sister showed mild malonic aciduria and other organic acid changes similar to the propositus, while the mother and half‐brother showed mildly elevated ketone bodies. This family suggests further genetic and clinical heterogeneity in the malonic acidurias.
Regulation of cholesterol biosynthetic pathway in patients with the Smith–Lemli–Opitz syndrome
Authors: Honda M. , Tint G. S. , Honda A. , Salen G. , Shefer S. , Batta A. K. , Matsuzaki Y. , Tanaka N.
Published: December 2002

The Smith–Lemli–Opitz syndrome (SLOS) is a recessively inherited birth disorder caused by a defect in 7‐dehydrocholesterol (3β‐hydroxysteroid) Δ7‐reductase, the final enzyme in cholesterol biosynthesis. To investigate in vivo regulation of the cholesterol biosynthetic pathway in SLOS, we measured hepatic microsomal sterol concentrations and activities of several key enzymes in the pathway, including HMG‐CoA synthase, HMG‐CoA reductase, squalene synthase and 7‐dehydrocholesterol Δ7‐reductase in liver specimens from a patient with SLOS and 11 controls. Hepatic microsomal 7‐dehydrocholesterol Δ7‐reductase activity in the patient was less than 1% of the control mean, and decreased cholesterol concentration and markedly increased 7‐ and 8‐dehydrocholesterol concentrations were observed in the patient's microsomes. HMG‐CoA synthase and squalene synthase activities in the patient were upregulated to 149% and 532%, respectively, while the activity of HMG‐CoA reductase, the rate‐limiting enzyme in the pathway, was reduced to 39% of the control mean. Downregulation of HMG‐CoA reductase activity in SLOS was supported by measuring plasma levels of mevalonic acid, the immediate product of HMG‐CoA reductase. The levels in SLOS patients (n=9) were significantly low compared with age‐matched controls (n=8) (12±2 vs 28±6 nmol/L, p<0.05). These results suggest that in most SLOS patients in vivo HMG‐CoA reductase is not stimulated in spite of blocked cholesterol biosynthetic pathway and reduced plasma and hepatic cholesterol concentrations.
Defective folding and rapid degradation of mutant proteins is a common disease mechanism in genetic disorders
Authors: Gregersen N. , Bross P. , Jørgensen M. M. , Corydon T. J. , Andresen B. S.
Published: December 2002

Many disease‐causing point mutations do not seriously compromise synthesis of the affected polypeptide but rather exert their effects by impairing subsequent protein folding or stability of the folded protein. This often results in rapid degradation of the affected protein. The concepts of such ‘conformational disease’ are illustrated by reference to cystic fibrosis, phenylketonuria and short‐chain acyl‐CoA dehydrogenase deficiency. Other cellular components such as chaperones and proteases, as well as environmental factors, may combine to modulate the phenotype of such disorders and this may open up new therapeutic approaches.
Ornithine carbamoyltransferase deficiency: Improved sensitivity of testing for protein tolerance in the diagnosis of heterozygotes
Authors: Potter M. , Hammond J. W. , Sim K.‐G. , Green A. K. , Wilcken B.
Published: December 2002

The most direct test of functional capacity of the liver in nitrogen disposal is to stress the urea cycle with a high protein load. This has been used in the diagnosis of heterozygosity for ornithine carbamoyltransferase deficiency for many years by measuring the subsequent excretion of orotic acid in urine. Reports have shown some ambiguity in both this and the more recent allopurinol test. We investigated the effects of different foods as the protein load and of different analytical methods. A standardized protocol was developed, giving 35 g protein per m2 surface area as steamed fat‐free chicken breast to be eaten within 30 min. Urine was collected at zero time and over 0–2, 2–4 and 4–6 h. Compliance was checked by assessing excretion of amino acids. Diagnostic sensitivity was improved by reference to the change in excretion, i.e. the ratio of excretions 2–4 h/0–2 h. Extension of the test to 6 h gave no diagnostic advantage over a 4 h test. Comparison of the analysis of total orotic acids by the photometric method of Harris and Oberholtzer, the reference method for this study, with that by the method of Goldstein and colleagues showed that the latter gave erratic results with some false positives. However, comparison of the method of Harris and Oberholtzer with specific orotic acid analysis by a modification of the stable‐isotope internal standard method of Rimoldi and colleagues yielded the same diagnoses. The improved protein load test gave a clearly positive result in all 16 obligate heterozygotes and 2 possible heterozygotes tested from 14 kindred, and a clearly negative result in all 18 control subjects and all 6 of the possible heterozygotes who were later shown by DNA studies not to carry the family mutation. The test appears at least as sensitive and specific as the allopurinol test, and is more convenient because of the short period of sample collection.
Why Have We Been More Successful in Reducing Tobacco Use Than Violent Crime?
Authors: Biglan Anthony , Taylor Ted K.
Published: December 2002

Tobacco control efforts have been associated with a significant reduction in the prevalence of tobacco use in the United States. Efforts to reduce the incidence of violent crime have been much less successful. This paper argues that progress on tobacco control stems from the existence of a clear, empirically based, and widely understood analysis of the tobacco problem that articulates (a) the harms associated with its use, (b) the causes of tobacco use, and (c) the programs and policies that could reduce tobacco use. This analysis has guided the development of a network of social organizations that have been advocating for policies and programs that are reducing tobacco use. In contrast, there is not a widely shared, cogent, and empirically based analysis of the problem of violent crime. As a result, efforts to combat violent crime are fragmented and it has proven difficult to generate support for preventive programs and policies. Substantial empirical progress has been made, however, on how violent crime could be prevented. That evidence is reviewed. It is argued that the articulation of this evidence is a critical first step for achieving widespread reduction in the incidence of violent crime. Communication of that evidence to audiences that matter will require that behavioral scientists become better organized to advocate for the adoption of empirically supported practices.
Quality and Ecology of Adversity as Common Mechanisms of Risk and Resilience
Authors: Sandler Irwin
Published: December 2002

This paper proposes common mechanisms to explain the effects of adversities and of resources that promote resilience. Adversities threaten the satisfaction of basic human needs and the acquisitions of competencies to carry out valued social roles. Adversities can also be characterized in terms of their ecological properties of occurrence in time, and place. Resilience resources at the individual, microsystem and macro levels reduce the negative effects of adversities through their effects on satisfaction of basic human needs and their effects on the occurrence of adversities. The effects of resilience resources are described as preventive, protective and promotive. Implications are presented for the development of interventions to promote resilience.
Biochemical and molecular analysis of an X‐linked case of Leigh syndrome associated with thiamin‐responsive pyruvate dehydrogenase deficiency
Authors: Naito E. , Ito M. , Yokota I. , Saijo T. , Matsuda J. , Osaka H. , Kimura S. , Kuroda Y.
Published: December 2002

We report molecular analysis of thiamin‐responsive pyruvate dehydrogenase complex (PDHC) deficiency in a patient with an X‐linked form of Leigh syndrome. PDHC activity in cultured lymphoblastoid cells of this patient and his asymptomatic mother were normal in the presence of a high thiamin pyrophosphate (TPP) concentration (0.4 mmol/L). However, in the presence of a low concentration (1 X 10‐4 mmol/L) of TPP, the activity was significantly decreased, indicating that PDHC deficiency in this patient was due to decreased affinity of PDHC for TPP. The patient's older brother also was diagnosed as PDHC deficiency with Leigh syndrome, suggesting that PDHC deficiency in these two brothers was not a de novo mutation. Sequencing of the X‐linked PDHC E1 α subunit revealed a C → G point mutation at nucleotide 787, resulting in a substitution of glycine for arginine 263. Restriction enzyme analysis of the E1α gene revealed that the mother was a heterozygote, indicating that thiamin‐responsive PDHC deficiency associated with Leigh syndrome due to this mutation is transmitted by X‐linked inheritance.