Successful reversal of propionic acidaemia associated cardiomyopathy: evidence for low myocardial coenzyme Q10 status and secondary mitochondrial dysfunction as an underlying pathophysiological mechanism

Dilated cardiomyopathy is a rare complication in propionic acidaemia (PA). Underlying pathophysiological mechanisms are poorly understood. We present a child of Pakistani consanguineous parents, diagnosed with late-onset PA at 18months of age. He presented a mild phenotype, showed no severe further decompensations, normal growth and psychomotor development on a low protein diet and carnitine supplementation. At 15years, a mildly dilated left ventricle was noticed. At 17years he presented after a 2-3month history of lethargy and weight loss with severe decompensated dilated cardiomyopathy. He was stabilised on inotropic support and continuous haemofiltration; a Berlin Heart biventricular assist device was implanted. He received d,l-hydroxybutyrate 200mg/kg/day, riboflavin and thiamine 200mg/day each and coenzyme Q10 (CoQ10). Myocardial biopsy showed endocardial fibrosis, enlarged mitochondria, with atypical cristae and slightly low respiratory chain (RC) complex IV activity relative to citrate synthase (0.012, reference range 0.014-0.034). Myocardial CoQ10 was markedly decreased (224pmol/mg, reference range 942-2738), with a marginally decreased white blood cell level (34pmol/mg reference range 37-133). The dose of CoQ10 was increased from 1.5 to 25mg/kg/day. Cardiomyopathy slowly improved allowing removal of the external mechanical cardiac support after 67days. We demonstrate for the first time low myocardial CoQ10 in cardiomyopathy in PA, highlighting secondary mitochondrial impairment as a relevant causative mechanism. According to these findings, a high-dose CoQ10 supplementation could be a potential adjuvant therapeutic to be considered in PA-related cardiomyopathy.

Prediction of outcome in isolated methylmalonic acidurias: combined use of clinical and biochemical parameters

Objectives Isolated methylmalonic acidurias (MMAurias) are caused by deficiency of methylmalonyl-CoA mutase or by defects in the synthesis of its cofactor 5'-deoxyadenosylcobalamin. The aim of this study was to evaluate which parameters best predicted the long-term outcome. Methods Standardized questionnaires were sent to 20 European metabolic centres asking for age at diagnosis, birth decade, diagnostic work-up, cobalamin responsiveness, enzymatic subgroup (mut(0), mut(-), cblA, cblB) and different aspects of long-term outcome. Results 273 patients were included. Neonatal onset of the disease was associated with increased mortality rate, high frequency of developmental delay, and severe handicap. Cobalamin non-responsive patients with neonatal onset born in the 1970s and 1980s had a particularly poor outcome. A more favourable outcome was found in patients with late onset of symptoms, especially when cobalamin responsive or classified as mut(-). Prevention of neonatal crises in pre-symptomatically diagnosed newborns was identified as a protective factor concerning handicap. Chronic renal failure manifested earlier in mut(0) patients than in other enzymatic subgroups. Conclusion Outcome in MMAurias is best predicted by the enzymatic subgroup, cobalamin responsiveness, age at onset and birth decade. The prognosis is still unfavourable in patients with neonatal metabolic crises and non-responsiveness to cobalamin, in particular mut(0) patients.

Two novel closure rules for constructing phylogenetic super-networks

A contemporary and fundamental problem faced by many evolutionary biologists is how to puzzle together a collection Weierstrass p of partial trees (leaf-labeled trees whose leaves are bijectively labeled by species or, more generally, taxa, each supported by, e.g., a gene) into an overall parental structure that displays all trees in Weierstrass p. This already difficult problem is complicated by the fact that the trees in Weierstrass p regularly support conflicting phylogenetic relationships and are not on the same but only overlapping taxa sets. A desirable requirement on the sought after parental structure, therefore, is that it can accommodate the observed conflicts. Phylogenetic networks are a popular tool capable of doing precisely this. However, not much is known about how to construct such networks from partial trees, a notable exception being the Z-closure super-network approach, which is based on the Z-closure rule, and the Q-imputation approach. Although attractive approaches, they both suffer from the fact that the generated networks tend to be multidimensional making it necessary to apply some kind of filter to reduce their complexity.To avoid having to resort to a filter, we follow a different line of attack in this paper and develop closure rules for generating circular phylogenetic networks which have the attractive property that they can be represented in the plane. In particular, we introduce the novel Y-(closure) rule and show that this rule on its own or in combination with one of Meacham's closure rules (which we call the M-rule) has some very desirable theoretical properties. In addition, we present a case study based on Rivera et al. "ring of life" to explore the reconstructive power of the M- and Y-rule and also reanalyze an Arabidopsis thaliana data set.

Diagnostic work-up and management of patients with isolated methylmalonic acidurias in European metabolic centres

The long-term outcome of patients with methylmalonic aciduria (MMA) is still uncertain due to a high frequency of complications such as chronic renal failure and metabolic stroke. The understanding of this disease is hampered by a huge variation in the management of these patients. The major aim of this study was to evaluate the current practice in different European metabolic centres. A standardized questionnaire was sent to 20 metabolic centres asking for standard procedures for confirmation of diagnosis, testing cobalamin responsiveness, dietary treatment, pharmacotherapy, and biochemical and clinical monitoring. Sixteen of 20 metabolic centres (80%) returned questionnaires on 183 patients: 89 of the patients were classified as mut(0), 36 as mut(-), 13 as cblA, 7 as cblB, and 38 as cblA/B. (1) Confirmation of diagnosis: All centres investigate enzyme activity by propionate fixation in fibroblasts; six centres also perform mutation analysis. (2) Cobalamin response: Ten centres follow standardized protocols showing large variations. A reliable exclusion of nonspecific effects has not yet been achieved by these protocols. (3) Long-term treatment: In cobalamin-responsive patients, most centres use hydroxocobalamin (1-14 mg/week i.m. or 5-20 mg/week orally), while two centres use cyanocobalamin. All cobalamin-nonresponsive patients and most cobalamin-responsive patients are supplemented with L: -carnitine (50-100 mg/kg per day). Fourteen centres use intestinal decontamination by antibiotic therapy. Most centres follow D-A-CH (n = 6) or Dewey (n = 4) recommendations for protein requirements. Fourteen centres regularly use precursor-free amino acid supplements. Standardized monitoring protocols are available in seven centres, again showing high variability.

Tissue distribution of the murine phosphomannomutases Pmm1 and Pmm2 during brain development

The most common type of the congenital disorders of glycosylation, CDG-Ia, is caused by mutations in the human PMM2 gene, reducing phosphomannomutase (PMM) activity. The PMM2 mutations mainly lead to neurological symptoms, while other tissues are only variably affected. Another phosphomannomutase, PMM1, is present at high levels in the brain. This raises the question why PMM1 does not compensate for the reduced PMM2 activity during CDG-Ia pathogenesis. We compared the expression profile of the murine Pmm1 and Pmm2 mRNA and protein in prenatal and postnatal mouse brain at the histological level. We observed a considerable expression of both Pmms in different regions of the embryonic and adult mouse brain. Surprisingly, the expression patterns were largely overlapping. This data indicates that expression differences on the cellular and tissue level are an unlikely explanation for the absence of functional compensation. These results suggest that Pmm1 in vivo does not exert the phosphomannomutase-like activity seen in biochemical assays, but either acts on as yet unidentified specific substrates or fulfils entirely different functions.

CDG-Id caused by homozygosity for an ALG3 mutation due to segmental maternal isodisomy UPD3(q21.3-qter)

We report on a patient with a congenital disorder of glycosylation type Id (CDG-Id) caused by a homozygous mutation in the ALG3 gene, which results from a de novo mutation in combination with a segmental maternal uniparental isodisomy (UPD). The patient presented with severe psychomotor delay, primary microcephaly, and opticus atrophy, compatible with a severe form of CDG. Isoelectric focusing of transferrin showed a type I pattern and lipid-linked oligosaccharide analysis showed an accumulation of dol-PP-GlcNAc2Man5 in patient's fibroblasts suggesting a defect in the ALG3 gene. A homozygous ALG3 missense mutation p.R266C (c.796C > T) was identified. Further evaluation revealed that neither the mother nor the father were carrier of the p.R266C mutation. Marker analysis revealed a segmental maternal isodisomy for the chromosomal region 3q21.3-3qter. UPD for this region has not been described before. More important, the combination of UPD with a de novo mutation is an exceptional coincidence and an extraordinary observation.

Biotinidase deficiency: a treatable leukoencephalopathy

The clinical history and the neuroradiological findings have been reviewed for 5 patients with biotinidase deficiency. Patients were diagnosed in the UK, where neonatal screening for this disorder is not done. The age at presentation ranged from 4 weeks to 5 months and the median interval between presentation and diagnosis was 5.5 months. The main abnormalities on cerebral imaging were leukoencephalopathy and widening of the ventricles and extra-cerebral CSF spaces. White matter abnormalities included delayed myelination but, in some patients, the increased signal was too great to be explained just by failure of myelination. Subtle subcortical changes were the only abnormality in one patient. Follow-up studies after treatment with biotin showed improved myelination; in one case, this was accompanied by normalisation of the CSF spaces but another patient showed progressive atrophy and cystic degeneration. Most of these patients have neurological sequelae. Biotinidase deficiency should be excluded in all patients with unexplained neurological problems. Neonatal screening provides the best chance of a good outcome.

How reliable is the allopurinol load in detecting carriers for ornithine transcarbamylase deficiency?

The allopurinol test aims to distinguish carriers and noncarriers for ornithine transcarbamylase (OTC) deficiency. We have evaluated the reliability of the test in at-risk females of known genotype. Results based on urine orotidine and/or orotic acid measurement were compared in terms of sensitivity and specificity. Retrospectively, we analysed the results of allopurinol tests in 42 women (22 confirmed heterozygotes and 20 noncarriers) from 23 pedigrees at risk of being carriers for OTC deficiency. Using a cut-off of 2 standard deviations above the mean of controls, the highest sensitivity (91%) was given by orotidine alone or in combination with orotic acid, but specificity was only 70% and 65%, respectively. We conclude that the value of the allopurinol test for detecting OTC carriers in at-risk females is limited. This needs to be recognized when counselling families. The test still has a role as a safe, quick, noninvasive screen of individuals at risk, but test results in possible carriers should be interpreted with caution. In the absence of other supportive evidence, confirmation by mutation analysis is required.

Abnormal lysosomal inclusions in liver hepatocytes but not in fibroblasts in congenital disorders of glycosylation (CDG)

We report a retrospective electron-microscopical study of liver biopsies and fibroblast cultures of 19 patients with congenital disorders of glycosylation (CDG) of different subtypes. A constant finding in liver biopsies of all CDG-I cases was that of abnormal lysosomal lamellar inclusions in the hepatocytes, which were not found in CDG-II. None of the patients showed significant abnormalities in their fibroblasts.

Cytochrome oxidase deficiency in Lowe syndrome

We report on a patient with complex IV deficiency who in later clinical course was diagnosed as a Lowe syndrome. Mitochondrial abnormalities can be present in Lowe syndrome and might lead to misdiagnosis, additionally because clinical features can be overlapping.

Neurological presentation of a congenital disorder of glycosylation CDG-Ia: implications for diagnosis and genetic counseling

The congenital disorders of glycosylation (CDG) constitute a new group of recessively inherited metabolic disorders that are characterized biochemically by defective glycosylation of proteins. Several types have been identified. CDG-Ia, the most frequent type, is a multisystemic disorder affecting the nervous system and numerous organs including liver, kidney, heart, adipose tissue, bone, and genitalia. A phosphomannomutase (PMM) deficiency has been identified in CDG-Ia patients and numerous mutations in the PMM2 gene have been identified in patients with a PMM deficiency. We report on a French family with 3 affected sibs, with an unusual presentation of CDG-Ia, remarkable for 1) the neurological presentation of the disease, and 2) the dissociation between intermediate PMM activity in fibroblasts and a decreased PMM activity in leukocytes. This report shows that the diagnosis of CDG-Ia must be considered in patients with non-regressive early-onset encephalopathy with cerebellar atrophy, and that intermediate values of PMM activity in fibroblasts do not exclude the diagnosis of CDG-Ia.

Identification and localization of two mouse phosphomannomutase genes, Pmm1 and Pmm2

Phosphomannomutases catalyze the reversible conversion of mannose 6-phosphate to mannose 1-phosphate. In humans, two different isozymes have recently been identified, PMM1 and PMM2. We have previously shown that mutations in the PMM2 gene cause the most frequent type of the congenital disorders of glycosylation, CDG-Ia. Here, we present data on the two mouse orthologous genes, Pmm1 and Pmm2. The chromosomal localization of the two mouse genes has been determined. We also present the gene structure and the exon-intron organization of Pmm1 and Pmm2. Pmm1 maps to mouse chromosome 15, Pmm2 to chromosome 16. These chromosomal regions are syntenic with regions on human chromosomes 22 and 16, respectively. The Pmm1 gene is composed of eight exons and spans approximately 9.5 kb. The genomic structure is extremely well conserved between the human and mouse gene. The Pmm2 gene consists of eight exons and spans a larger genomic region ( approximately 20 kb). An alignment of the human and mouse protein sequences confirms the conservation among this family of phosphomannomutases. The two mouse genes are expressed in many tissues, but the expression pattern is slightly different between Pmm1 and Pmm2. The most striking difference is the high expression of Pmm1 in brain tissue, whereas Pmm2 is only weakly expressed in this tissue.

Enhanced internal dynamics of a membrane transport protein during substrate translocation

Conformational changes are essential for the activity of many proteins. If, or how fast, internal fluctuations are related to slow conformational changes that mediate protein function is not understood. In this study, we measure internal fluctuations of the transport protein lactose permease in the presence and absence of substrate by tryptophan fluorescence spectroscopy. We demonstrate that nanosecond fluctuations of alpha-helices are enhanced when the enzyme transports substrate. This correlates with previously published kinetic data from transport measurements showing that millisecond conformational transitions of the substrate-loaded carrier are faster than those in the absence of substrate. These findings corroborate the hypothesis of the hierarchical model of protein dynamics that predicts that slow conformational transitions are based on fast, thermally activated internal motions.

Clinical and biochemical characteristics of congenital disorder of glycosylation type Ic, the first recognized endoplasmic reticulum defect in N-glycan synthesis

We report on 8 patients with a recently described novel subtype of congenital disorder of glycosylation type Ic (CDG-Ic). Their clinical presentation was mainly neurological with developmental retardation, muscular hypotonia, and epilepsy. Several symptoms commonly seen in CDG-Ia such as inverted nipples, abnormal fat distribution, and cerebellar hypoplasia were not observed. The clinical course is milder overall, with a better neurological outcome, than in CDG-Ia. The isoelectric focusing pattern of serum transferrin in CDG-Ia and CDG-Ic is indistinguishable. Interestingly, beta-trace protein in cerebrospinal fluid derived from immunoblot analysis of the brain showed a less pronounced hypoglycosylation pattern in CDG-Ic patients than in CDG-Ia patients. Analysis of lipid-linked oligosaccharides revealed an accumulation of Man9GlcNAc2 intermediates due to dolichol pyrophosphate-Man9GlcNAc2 alpha-1,3 glucosyltransferase deficiency. All patients were homozygous for an A333V mutation.

Multi-allelic origin of congenital disorder of glycosylation (CDG)-Ic

Congenital disorders of glycosylation (CDG), formerly known as carbohydrate-deficient glycoprotein syndrome, represent a family of genetic diseases with variable clinical presentations. Common to all types of CDG characterized to date is a defective Asn-linked glycosylation caused by enzymatic defects of N-glycan synthesis. Previously, we have identified a mutation in the ALG6 alpha1,3 glucosyltransferase gene as the cause of CDG-Ic in four related patients. Here, we present the identification of seven additional cases of CDG-Ic among a group of 35 untyped CDG patients. Analysis of lipid-linked oligosaccharides in fibroblasts confirmed the accumulation of dolichyl pyrophosphate-Man9GlcNAc2 in the CDG-Ic patients. The genomic organization of the human ALG6 gene was determined, revealing 14 exons spread over 55 kb. By polymerase chain reaction amplification and sequencing of ALG6 exons, three mutations, in addition to the previously described A333 V substitution, were detected in CDG-Ic patients. The detrimental effect of these mutations on ALG6 activity was confirmed by complementation of alg6 yeast mutants. Haplotype analysis of CDG-Ic patients revealed a founder effect for the ALG6 allele bearing the A333 V mutation. Although more than 80% of CDG are type Ia, CDG-Ic may be the second most common form of the disease.

beta-Trace protein in human cerebrospinal fluid: a diagnostic marker for N-glycosylation defects in brain

As carbohydrate-deficient glycoprotein syndromes (CDGS) are multisystemic disorders with impaired central nervous function in nearly all cases, we tested isoforms of beta-trace protein (beta TP), a 'brain-type' glycosylated protein in cerebrospinal fluid (CSF) of nine patients with the characteristic CDGS type I pattern of serum transferrin. Whereas the serum transferrin pattern did not discriminate between the various subtypes of CDGS type I (CDGS type Ia, type Ic, and patients with unknown defect), beta TP isoforms of CDGS type Ia patients differed from that of the other CDGS type I patients. The percentage of abnormal beta TP isoforms correlated with the severity of the neurological symptoms. Furthermore, two patients are described, who illustrate that abnormal protein N-glycosylation can occur restricted to either the 'peripheral' serum or the central nervous system compartment. This is the first report presenting evidence for an N-glycosylation defect restricted to the brain. Testing beta TP isoforms is a useful tool to detect protein N-glycosylation disorders in the central nervous system.

Effect of mutations found in carbohydrate-deficient glycoprotein syndrome type IA on the activity of phosphomannomutase 2

Seven mutant forms of human phosphomannomutase 2 were produced in Escherichia coli and purified. These mutants had a Vmax of 0.2-50% of the wild enzyme and were unstable. The least active protein (R141H) bears a very frequent mutation, which has never been found in the homozygous state whereas the second least active protein (D188G) corresponds to a mutation associated with a particularly severe phenotype. We conclude that total lack of phosphomannomutase 2 is incompatible with life. Another conclusion is that the elevated residual phosphomannomutase activity found in fibroblasts of some patients is contributed by their mutated phosphomannomutase 2.

Role of heteromer formation in GABAB receptor function

Recently, GBR1, a seven-transmembrane domain protein with high affinity for gamma-aminobutyric acid (GABA)B receptor antagonists, was identified. Here, a GBR1-related protein, GBR2, was shown to be coexpressed with GBR1 in many brain regions and to interact with it through a short domain in the carboxyl-terminal cytoplasmic tail. Heterologously expressed GBR2 mediated inhibition of adenylyl cyclase; however, inwardly rectifying potassium channels were activated by GABAB receptor agonists only upon coexpression with GBR1 and GBR2. Thus, the interaction of these receptors appears to be crucial for important physiological effects of GABA and provides a mechanism in receptor signaling pathways that involve a heterotrimeric GTP-binding protein.

Lipid composition of Spodoptera frugiperda (Sf9) and Trichoplusia ni (Tn) insect cells used for baculovirus infection

The lipid composition of two different insect cell lines from Spodoptera frugiperda (Sf9) and Trichoplusia ni (Tn) which are established cell lines for infection with recombinant baculovirus was analyzed by high-performance liquid chromatography and gas-liquid chromatography. The major phospholipids found were phosphatidylcholine and phosphatidylethanolamine, the major mono-unsaturated fatty acids were oleic acid and palmitoleic acid, the major saturated fatty acid was stearic acid. The cholesterol to phospholipid ratio was demonstrated to be lower than in mammalian cell lines. Infection with a recombinant baculovirus Autographa californica resulted in increased levels of phosphatidylcholine in the insect cells. The baculovirus/insect cell system has become a popular system for heterologous protein production. Functional changes of membrane proteins produced in these two cell lines might be correlated to a different lipid profile of their cellular membranes.

Pregnancy in a woman with maple syrup urine disease

We present the favourable outcome of a pregnancy in a woman with maple syrup urine disease. Keeping the maternal plasma levels of the branched-chain amino acids between 100 and 300 mumol/L is compatible with delivery of a normal infant. Leucine tolerance increased progressively from the 22nd week of gestation from 350 to 2100 mg/day. The risk of metabolic decompensation in the postpartum period can be minimized by careful monitoring of the mother after delivery.

Glycosylation, palmitoylation, and localization of the human D2S receptor in baculovirus-infected insect cells

In order to evaluate the baculovirus expression system as a means for high-yield production of homogeneous D2S receptor, we have expressed various D2S receptor constructs in two Spodoptera frugiperda cell lines, a Trichoplusia ni and a Mammestra brassicae cell line. To improve expression yield, the environment of the polyhedrin gene translational initiation site was retained by fusing the first 12 codons of the polyhedrin gene to the 5'-end of the D2S receptor coding sequence. The pharmacological profile of the expressed D2S receptor was similar to that reported for neuronal D2 receptors. Sf9 and Tn cells were best suited for overexpression, yielding about 2 x 10(6) and 4 x 10(6) receptors/cell, respectively, corresponding to 6 pmol/mg of cell protein in Sf9 cells and 10 pmol/mg of cell protein in Tn cells. We have developed a D2 receptor-specific anti-peptide antibody to study glycosylation, palmitoylation, and localization of the heterologously produced receptor. Immunoprecipitation of digitonin/cholate-solubilized receptor from control and tunicamycin-treated Sf9, Tn, and Mb cells revealed an apparent molecular mass of 47-48 kDa for the glycosylated receptor and of 39-40 kDa for the unglycosylated receptor. Although pulse-chase studies showed that glycosylation occurred rapidly and efficiently, the glycosylated receptor only constituted a small fraction of the overall produced receptor protein, which was mainly located intracellularly. The glycosylation of the receptor was of the high-mannose-type in contrast to the complex-type glycosylation found in native tissue. The glycosylated D2S receptor was palmitoylated. Glycosylation, however, was not a prerequisite for palmitoylation which was insensitive to tunicamycin, brefeldin A, and monensin. NH2-terminal addition of the signal sequence of prepromelittin to the D2S receptor increased expression levels 2-3-fold and significantly enhanced membrane insertion and processing, resulting in increased targeting of the synthesized receptor to the plasma membrane.

In vivo reconstitution of dopamine D2S receptor-mediated G protein activation in baculovirus-infected insect cells: preferred coupling to Gi1 versus Gi2

Agonist binding of the human D2S receptor overexpressed in baculovirus-infected Sf9 insect cells was of low affinity and GppNHp-insensitive, yet, dopaminergic agonists were able to partly inhibit forskolin-stimulated cAMP accumulation. In order to prove full functionality of the receptor, we used an "in vivo" reconstitution system, which is based on coinfection of Sf9 cells with the appropriate receptor and G protein encoding baculoviruses. In cells coexpressing the D2S receptor and either Gi1 or Gi2, the dopaminergic agonist apomorphine effectively stimulated [35S]GTP gamma S binding and GTPase activity. Agonist-stimulated [35S]GTP gamma S binding was dependent on the ratio of G protein to receptor. Expression levels of receptor and G protein influenced each other reciprocally. G protein activation could be optimized by varying the multiplicity of infection of the receptor and G protein encoding baculoviruses. Coexpression of either Gi1 or Gi2 led to the appearance of GppNHp-sensitive high-affinity agonist binding. Detailed agonist competition binding analysis revealed that the percentage of high-affinity agonist binding sites was significantly higher in D2S receptor-expressing cells coinfected with Gi1 viruses than when coinfected with Gi2 viruses. Moreover, the coexpressed Gi proteins seemed to modulate the affinity of agonists for the high-affinity form of the receptor. In cells coexpressing Gi1, agonist high affinity was 2-4-fold higher than in cells coexpressing Gi2. Na+ increased the dissociation constant of apomorphine for the high-affinity site by 2-4-fold without affecting the percentage of high-affinity sites or the preference for Gi1. In some dopamine competition experiments with coinfected cells, displacement data were best fit assuming three noninteracting classes of sites in the absence and two independent classes of sites in the presence of GppNHp. Dopamine competition curves with cells highly overexpressing the D2S receptor or with membranes from such cells were best fit assuming two independent classes of sites which were insensitive to GppNHp and might reflect abnormal compartimentalization and/or different states of aggregation.

Fast spin-echo MR imaging of the pediatric brain

On a 1.5-T MR unit conventional spin-echo (CSE) and fast spin-echo (FSE) images were obtained in 70 consecutive children ranging from 4 days to 13 years in age. They suffered from developmental retardation, neurodegenerative, ischemic or inflammatory diseases. In our prospective study artifacts, lesion conspicuity and general impression were compared between double-echo (proton density- and T2-weighted) CSE and single-echo (T2-weighted) FSE images. Phase artifacts from flowing blood were seen rarely on the FSE images, while motion artifacts appeared more frequently. Assessment of myelination in 43 children with unfinished myelination revealed no difference between FSE and CSE. The lesion conspicuity in 20 children with focal abnormalities compared favorably between FSE and CSE. There was no diagnostically relevant difference between FSE and CSE, although in FSE spin density images were missing. FSE sequences can be used in MR imaging of the pediatric brain without disadvantage and with a time reduction of 67-75%.

Heterologous expression of the human D2S dopamine receptor in protease-deficient Saccharomyces cerevisiae strains

The cDNA for the human D2S dopamine receptor has been functionally expressed in the unicellular yeast Saccharomyces cerevisiae. The original D2S gene and an elongated D2S gene with an N-terminal fusion to the first 24 amino acids of the STE2 gene from S. cerevisiae were introduced into the episomal yeast expression vector YEp51 under the control of the GAL10 promoter. Expression studies performed in a wild-type strain and in two protease-deficient strains of S. cerevisiae revealed that the receptor was functionally expressed with respect to its ligand-binding properties. The KD values for the binding of the dopamine antagonist [3H]spiperone were calculated to be 1.6 nM for the D2S receptor alone and 1.9 nM for the STE2-D2S chimaera. Both membrane proteins could be further characterized by ligand-displacement studies using certain dopamine agonists and antagonists. D2S dopamine-receptor-specific polyclonal antibodies were used to monitor the heterologous expression of the receptor. Western-blot analysis of membranes prepared from transformed yeast cells producing either the receptor protein alone or the receptor fusion protein revealed apparent molecular masses of 40 kDa (D2S receptor alone) and 42 kDa (STE2/D2S receptor fusion protein). It could be shown that, in comparison to the expression in a wild-type S. cerevisiae strain, the amount of receptor degradation was drastically reduced in the protease-deficient strains. The localizations of the heterologously produced dopamine receptor and of the chimaera in the recombinant yeast were studied by immunogold electron microscopy and were found to be restricted mainly to the vacuole of the cells.

Constitutive expression of the human D2S-dopamine receptor in the unicellular yeast Saccharomyces cerevisiae

The cDNA for the human D2S-dopamine receptor has been functionally expressed in the unicellular yeast Saccharomyces cerevisiae. Two expression plasmids pRS421D2 (original D2S-gene coding region) and pRS421D2S (the first 24 aa of the yeast STE2-gene are fused to the N-terminus of the D2S-gene) were constructed and transformed into the protease deficient S. cerevisiae strain cI3-ABYS-86. Northern blot analysis of total RNA from transformed yeast clones revealed that for both constructs the D2S-gene was constitutively transcribed from the plasmids PMA1 promoter. Membranes prepared from recombinant S. cerevisiae exhibited saturable binding with the antagonist [3H]methylspiperone. Competition studies revealed pharmacological properties for these sites which were comparable to those reported for the D2-receptor heterologously expressed in mammalian cells. The expression of the receptor was monitored by Western blot analysis using an antiserum raised against a peptide from the third intracellular domain of the receptor protein and by ligand binding assay.

Expression of the human D2S dopamine receptor in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe: a comparative study

The yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe were tested for heterologous expression of the human D2S dopamine receptor. The cDNA coding for the dopamine receptor was cloned into high copy number plasmids with inducible promoters. After transformation into the yeasts recombinant clones were examined for the presence of functional receptor by radioligand binding using the antagonist [3H]spiperone. Subsequent Western blot analysis of positive recombinants with an antiserum raised against a peptide from the third intracellular domain of the receptor protein revealed the production of a protein with an apparent molecular mass of 40 kDa in both yeasts. Membranes harvested from recombinant yeast clones exhibited saturable binding of the dopaminergic antagonist [3H]spiperone with Kd values of 1.3 nM in S. cerevisiae and 0.25 nM in S. pombe. The rank order of potencies for several dopaminergic ligands to displace specific [3H]spiperone binding to membranes were the same in both yeasts, whereas the affinities for ligands differed significantly.

[Immunoglobulin therapy in patients after autologous and allogeneic bone marrow transplantation]

Following bone marrow transplantation many patients are suffering from an impaired immunoglobulin production. Treatment with intravenous immunoglobulin has significantly reduced the incidence of infections as well as severe graft-versus-host disease during the early posttransplant period. However, no complete protection of the patients has been achieved. According to our own observations, especially patients with a decreased production of IgM antibodies seem to have an increased risk of cytomegalovirus-induced pneumonitis. During the late posttransplant period, patients with IgG subclass deficiency are at risk of acquiring gram-positive infections. However, randomized studies investigating the effect of immunoglobulin treatment during the late posttransplant phase have not yet been conducted.

Immunglobulintherapie bei Patienten nach autologer und allogener Knochenmarktransplantation

Bei Patienten nach Knochenmarktransplantation besteht 1-2 Jahre nach der Transplantation eine eingeschränkte Bildung von Immunglobulinen. Durch die intravenöse Gabe von Immunglobulinen konnte die Inzidenz von bakteriellen und viralen Infektionen sowie auch die der schweren Transplantat-Wirt-Reaktion während der frühen Phase nach der Transplantation (bis Tag 100) signifikant gesenkt werden, ohne jedoch einen vollständigen Schutz für die Patienten zu bieten. So scheint insbesondere der Mangel an IgM-Antikörpern bei den von uns untersuchten Patienten für eine durch Zytomegalieviren verursachte Pneumonie zu prädestinieren. Während der späten Phase nach der Transplantation sind insbesondere Patienten mit IgG-Subklas-sen-Defekten durch Infektionen mit grampositiven Erregern gefährdet. Es gibt jedoch noch keine randomisierten Studien, die den Einsatz von Immunglobulinen während dieser Phase nach der Knochenmarktransplantation untersucht haben.