bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of energy metabolism by 2‐methylacetoacetate and 2‐methyl‐3‐hydroxybutyrate in cerebral cortex of developing rats
Authors: Rosa R. B. , Schuck P. F. , Assis D. R. de , Latini A. , Dalcin K. B. , Ribeiro C. A. J. , Ferreira G. da C. , Maria R. C. , Leipnitz G. , Perry M. L. S. , Filho C. S. Dutra , Wyse A. T. S. , Wannmacher C. M. D. , Wajner M. 
Published: May 2005

SummaryMitochondrial β‐ketothiolase and 2‐methyl‐3‐hydroxybutyryl‐CoA dehydrogenase (MHBD) deficiencies are inherited neurometabolic disorders affecting isoleucine catabolism. Biochemically, β‐ketothiolase deficiency is characterized by intermittent ketoacidosis and urinary excretion of 2‐methyl‐acetoacetate (MAA), 2‐methyl‐3‐hydroxybutyrate (MHB) and tiglylglycine (TG), whereas in MHBD deficiency only MHB and tiglylglycine accumulate. Lactic acid accumulation and excretion are also observed in these patients, being more pronounced in MHBD‐deficient individuals, particularly during acute episodes of decompensation. Patients affected by MHBD deficiency usually manifest severe mental retardation and convulsions, whereas β‐ketothiolase‐deficient patients present encephalopathic crises characterized by metabolic acidosis, vomiting and coma. Considering that the pathophysiological mechanisms responsible for the neurological alterations of these disorders are unknown and that lactic acidosis suggests an impairment of energy production, the objective of the present work was to investigate the in vitro effect of MAA and MHB, at concentrations varying from 0.01 to 1.0 mmol/L, on several parameters of energy metabolism in cerebral cortex from young rats. We observed that MAA markedly inhibited CO2 production from glucose, acetate and citrate at concentrations as low as 0.01 mmol/L. In addition, the activities of the respiratory chain complex II and succinate dehydrogenase were mildly inhibited by MAA. MHB, at 0.01 mmol/L and higher concentrations, strongly inhibited CO2 production from all tested substrates, as well as the respiratory chain complex IV activity. The other activities of the respiratory chain were not affected by these metabolites. The data indicate a marked blockage in the Krebs cycle and a mild inhibition of the respiratory chain caused by MAA and MHB. Furthermore, MHB inhibited total and mitochondrial creatine kinase activities, which was prevented by the use of the nitric‐oxide synthase inhibitor L‐NAME and glutathione (GSH). These data indicate that the effect of MHB on creatine kinase was probably mediated by oxidation or other modification of essential thiol groups of the enzyme by nitric oxide and other by‐products derived from this organic acid. In contrast, MAA did not affect creatine kinase activity. Taken together, these observations indicate that aerobic energy metabolism is inhibited by MAA and to a greater extent by MHB, a fact that may be related to lactic acidaemia occurring in patients affected by MHBD and β‐ketothiolase deficiencies. If the in vitro effects detected in the present study also occur in vivo, it is tempting to speculate that they may contribute, at least in part, to the neurological dysfunction found in these disorders.
Management of methylmalonic acidaemia by combined liver–kidney transplantation
Authors: Nagarajan S. , Enns G. M. , Millan M. T. , Winter S. , Sarwal M. M. 
Published: May 2005

SummaryMethylmalonic acidaemia (MMA) is a rare autosomal recessive inborn error of metabolism that typically presents in infancy with recurrent episodes of metabolic acidosis, developmental delay and failure to thrive. The disease course is complicated by the development of chronic tubulointerstitial nephritis progressing to end‐stage renal disease in adolescence. We describe two adolescents with cobalamin‐nonresponsive MMA (mut0) who developed polyuria, chronic tubulointerstitial nephritis, dystonia but normal synthetic liver function. Both patients received combined liver–kidney transplantation (CLKT), preceded by a single pretransplant haemodialysis for clearance of methylmalonic acid. Post CLKT there was 95–97% reduction in serum and urine methylmalonic acid, leading to significant liberalization of dietary protein intake and a consequent increase in body mass index, muscle strength and energy. In addition, renal function normalized and clinical neurological status stabilized. We propose that CLKT be considered as a therapeutic option early in the course of cobalamin‐nonresponsive MMA. Progressive tubulointerstitial nephritis with disabling polyuria is a confounder in patient management even in the absence of end‐stage renal disease. Successful CLKT restores methylmalonyl‐CoA mutase enzyme levels in the liver and kidney, improves clearance of methylmalonic acid with resultant dietary protein liberalization, and offers excellent graft and patient outcomes with improvement in quality of life.
OPA3 mutation screening in patients with unexplained 3‐methylglutaconic aciduria
Authors: Neas K. , Bennetts B. , Carpenter K. , White R. , Kirk E. P. , Wilson M. , Kelley R. , Baric I. , Christodoulou J. 
Published: May 2005

SummaryWe have screened 13 patients with neurological abnormalities and 3‐methylglutaconic aciduria (3MGA) for mutations in the OPA3 gene, which are known to be the cause of Costeff syndrome (optic atrophy, chorea and spasticity; type III 3MGA). We aimed to explore whether mutations in the OPA3 gene are present in patients with 3MGA but without classic Costeff syndrome. OPA3 mutations (IVS1−1G>C) were identified in 2 patients with the classic phenotype of type III 3MGA, but not in the other 11 patients with differing non‐Costeff phenotypes associated with developmental delay and neurological signs and symptoms as described. We identified a previously described sequence variation in the OPA3 gene (c.231T>C) in 12/13 patients. The alteration was homozygous in 8/12 and heterozygous in 4/12. This alteration was also found in 60 of 98 normal control alleles. In a single patient, a novel sequence variation in the 5′ UTR was identified, (c.−38A>G). Our studies suggest that the c.231T>C sequence variation is of no clinical significance, whereas the significance of the 5′ UTR sequence variation remains open to speculation. Our study of the OPA3 gene in patients with 3MGA without Costeff syndrome suggests that mutations in OPA3 are not a common cause of 3MGA in the absence of signs of Costeff syndrome.
Biochemical, clinical and molecular findings in LCHAD and general mitochondrial trifunctional protein deficiency
Authors: Olpin S. E. , Clark S. , Andresen B. S. , Bischoff C. , Olsen R. K. J. , Gregersen N. , Chakrapani A. , Downing M. , Manning N. J. , Sharrard M. , Bonham J. R. , Muntoni F. , Turnbull D. N. , Pourfarzam M. 
Published: May 2005

SummaryGeneral mitochondrial trifunctional protein (TFP) deficiency leads to a wide clinical spectrum of disease ranging from severe neonatal/infantile cardiomyopathy and early death to mild chronic progressive sensorimotor poly‐neuropathy with episodic rhabdomyolysis. Isolated long‐chain 3‐hydroxyacyl‐CoA dehydrogenase (LCHAD) deficiency resulting from the common Glu510Gln mutation usually gives rise to a moderately severe phenotype with multiorgan involvement with high morbidity and mortality. However, isolated LCHAD deficiency can also be consistent with long‐term survival in patients identified and treated from an early age. We present biochemical, clinical and mutation data in 9 patients spanning the full spectrum of disease. Fibroblast acylcarnitine profiling shows good correlation with clinical phenotype using the ratio C18(OH)/(C14(OH)+C12(OH)). This ratio shows a gradation of values, from high in four patients with severe neonatal disease (2.5±0.8), to low in two neuromyopathic patients (0.35, 0.2). Fibroblast fatty acid oxidation flux assays also show correlation with the patient phenotype, when expressed either as percentage residual activity with palmitate or as a ratio of percentage activity of myristate/oleate (M/O ratio). Fibroblasts from four patients with severe neonatal disease gave an M/O ratio of 4.0±0.6 compared to 1.97 and 1.62 in two neuromyopathic patients. Specific enzyme assay of LCHAD and long‐chain 3‐ketothiolase activity in patient cells shows lack of correlation with phenotype. These results show that measurements in intact cells, which allow all determinative and modifying cellular factors to be present, better reflect patient phenotype. Mutation analysis reveals a number of α‐ and β‐subunit mutations. Peripheral sensorimotor polyneuropathy, often as the initial major presenting feature but usually later accompanied by episodic rhabdomyolysis, is a manifestation of mild TFP protein deficiency. The mild clinical presentation and relative difficulty in diagnosis suggest that this form of TFP is probably underdiagnosed.
Newborns with C8‐acylcarnitine level over the 90th centile have an increased frequency of the common MCAD 985A>G mutation
Authors: Blois B. , Riddell C. , Dooley K. , Dyack S. 
Published: May 2005

SummaryMedium chain acyl‐coenzyme A dehydrogenase (MCAD) deficiency is the most commonly inherited defect of fatty acid oxidation. This autosomal recessive disorder is characterized by the tendency to become profoundly hypoglycaemic under fasting stress conditions, leading to lethargy, coma, brain injury and/or death. The most common mutation resulting in MCAD deficiency ascertained through individuals of northern European descent presenting with clinical symptoms is a single base‐pair change (985A>G) that accounts for up to 90% of these abnormal alleles. In the general Nova Scotia population, which comprises largely individuals of northern European descent, this mutation is present at a frequency of 1 in 68. A recently implemented newborn screening programme for MCAD deficiency uses tandem mass spectrometry (MS/MS) to analyse blood spots from newborns for C8‐acylcarnitine. After reviewing initial data from this newborn screening programme, we hypothesized that there was an unexpectedly high frequency of individuals with an MCAD 985A>G mutation and C8‐acylcarnitine levels at the upper end of the normal range. A sample representing the upper 90th centile was screened for the presence of the 985A>Gmutation and 61 heterozygotes were identified, establishing a high frequency (1/10) of this 985A>G mutation in this selected population. We have demonstrated a relationship between heterozygosity for 985A>G and C8‐acylcarnitine levels. These results contribute to the interpretation of C8‐acylcarnitine levels and the establishment of a more clinically relevant screening cut‐off point.
Impaired myocardial perfusion reserve but preserved peripheral endothelial function in patients with Fabry disease
Authors: Kalliokoski R. J. , Kalliokoski K. K. , Sundell J. , Engblom E. , Penttinen M. , Kantola I. , Raitakari O. T. , Knuuti J. , Nuutila P. 
Published: May 2005

SummaryFabry disease (McKusick 301500) is an X‐linked lysosomal storage disorder due to deficient α‐galactosidase A activity, which leads to accumulation of glycosphingolipids, especially in vascular smooth‐muscle and endothelial cells. The effect of this accumulation on peripheral and cardiac vascular function is poorly known. We studied 15 Fabry patients (mean age 35 years and mean BMI 24.8 kg/m2) and 30 age‐ and BMI‐matched healthy controls to examine whether myocardial perfusion reserve and peripheral artery endothelial function are altered. Myocardial perfusion was measured at rest and during dipyridamole‐induced hyperaemia by positron emission tomography and H215O. Myocardial blood flow reserve was calculated as the ratio between the dipyridamole‐induced maximal blood flow and resting blood flow. Peripheral artery endothelial function was assessed by measuring the brachial artery flow‐mediated dilatation using ultrasound at rest and during reactive hyperaemia. The myocardial perfusion reserve was significantly lower in Fabry patients than in controls (3.3 ± 1.2 vs 4.4 ± 1.6, p = 0.02), while the brachial artery flow‐mediated dilatation was similar (5.9% ± 3.9%vs 4.5% ± 3.6%, p = 0.27). Thus, inFabry disease, myocardial perfusion reserve is reduced while the peripheral artery endothelial function is preserved.
Enzyme replacement therapy in Japanese Fabry disease patients: The results of a phase 2 bridging study
Authors: Eto Y. , Ohashi T. , Utsunomiya Y. , Fujiwara M. , Mizuno A. , Inui K. , Sakai N. , Kitagawa T. , Suzuki Y. , Mochizuki S. , Kawakami M. , Hosoya T. , Owada M. , Sakuraba H. , Saito H. 
Published: May 2005

SummaryFabry Disease (α‐galactosidase A deficiency) is an X‐linked hereditary disorder leading to the pathological accumulation of globotriaosylceramide (GL‐3) in lysosomes, particularly in the vascular endothelium of the kidney, heart and brain. We report the results of an open‐label phase 2 study that was undertaken to evaluate whether ethnic differences exist that would affect agalsidase beta (Fabrazyme) treatment of Fabry patients in the Japanese population, relative to safety and efficacy. The study design mirrored the design of the completed phase 3 clinical trial that led to approval of the product agalsidase beta. The 13 Japanese, male Fabry patients enrolled in the study received the enzyme replacement therapy over a period of 20 weeks as biweekly infusions. All selected efficacy end points showed improvements that were comparable with findings from the phase 3 study. These improvements included reductions of GL‐3 accumulation in both kidney and skin capillary endothelial cells to (near) normal levels (92% of patients). Kidney and plasma GL‐3 levels decreased by 51.9% and 100%, respectively, by ELISA. Renal function remained normal. Fabry‐associated pain, and quality of life, showed improvement over baseline in multiple categories. Related adverse events were mild or moderate in intensity and mostly infusion‐associated (fever and rigors). As expected, IgG antibody formation was observed in 85% of the patients, but had no effect on treatment response. These results suggest that treatment with agalsidase beta is safe and effective in Japanese patients with Fabry disease. With regard to safety and efficacy, no differences were observed as compared to the caucasian population.
Early diagnosis of mucopolysaccharidosis III A with a nonsense mutation and two de novo missense mutations in SGSH gene
Authors: Bekri S. , Armana G. , Ricaud D. De , Osenda M. , Maire I. , Obberghen E. Van , Froissart R. 
Published: May 2005

SummaryAn early presentation of heparan N‐sulphatase (SGSH) deficiency (mucopolysaccharidosis IIIA, MPS IIIA) with a prominent and isolated hepato‐splenomegaly is described. Molecular analysis detected a nonsense mutation (Y40X) and two de novo missense mutations (E300V; Q307P).
Clinical response to sildenafil in pulmonary hypertension associated with Gaucher disease
Authors: Fernandes C. J. C. , Jardim C. , Carvalho L. A. S. , Farias A. Q. , Filho M. Terra , Souza R. 
Published: May 2005

SummaryThere are few reports of pulmonary hypertension in Gaucher disease. We report a patient who showed significant clinical improvement after treatment with sildenafil.
Absolute configuration of N‐acetylaspartate in urine from patients with Canavan disease
Authors: Bal D. , Gryff‐Keller A. , Gradowska W. 
Published: May 2005

SummaryHigh‐resolution 1H and 13C NMR of N‐acetylaspartic acid as its 2‐(S)‐butyl diester allows the two enantiomers to be unambiguously identified. Analysis of urine samples from five patients with Canavan disease (N‐aspartoacylase deficiency) showed that more than 95% of the excreted N‐acetylaspartate had the S‐configuration.
Key roles of hydrophobic rings of TM2 in gating of the α9α10 nicotinic cholinergic receptor
Authors: Plazas Paola V , De Rosa María J , Gomez‐Casati María E , Verbitsky Miguel , Weisstaub Noelia , Katz Eleonora , Bouzat Cecilia , Elgoyhen Ana Belén 
Published: May 2005

We have performed a systematic mutagenesis of three hydrophobic rings (17′, 13′ and 9′) within transmembrane region (TM) 2 of the α9α10 nicotinic cholinergic receptor (nAChR) to a hydrophilic (threonine) residue and compared the properties of mutant receptors reconstituted in Xenopus laevis oocytes.
Phenotypic changes in α9α10 mutant receptors were evidenced by a decrease in the desensitization rate, an increase in both the EC50 for ACh as well as the efficacy of partial agonists and the reduction of the allosteric modulation by extracellular Ca2+.
Mutated receptors exhibited spontaneous openings and, at the single‐channel level, an increased apparent mean open time with no major changes in channel conductance, thus suggesting an increase in gating of the channel as the underlying mechanism.
Overall, the degrees of the phenotypes of mutant receptors were more overt in the case of the centrally located V13′T mutant.
Based on the atomic model of the pore of the electric organ of the Torpedo ray, we can propose that the interactions of side chains at positions 13′ and 9′ are key ones in creating an energetic barrier to ion permeation.
In spite of the fact that the roles of the TM2 residues are mostly conserved in the distant α9α10 member of the nAChR family, their mechanistic contributions to channel gating show significant differences when compared to other nAChRs. These differences might be originated from slight differential intramolecular rearrangements during gating for the different receptors and might lead each nAChR to be in tune with their physiological roles.

British Journal of Pharmacology (2005) 145, 963–974. doi:10.1038/sj.bjp.0706224
Lipids modulate ligand binding to sulphonylurea receptors
Authors: Klein Alexander , Lichtenberg Jochen , Stephan Damian , Quast Ulrich 
Published: May 2005

ATP‐sensitive K+ channels (KATP channels) are complexes of inwardly rectifying K+ channels (Kir6.x) and sulphonylurea receptors (SURs). Kir6.2‐containing channels are closed by ATP binding to Kir6.2, and opened by MgADP binding to SUR. Channel activity is modulated by synthetic compounds such as the channel‐blocking sulphonylureas and the KATP channel openers, which both act by binding to SUR. By interacting with Kir6.2, phosphatidylinositol‐4,5‐bisphosphate (PIP2) and oleoyl‐coenzyme A (OCoA) decrease the ATP‐sensitivity of the channel and abolish the effect of the synthetic channel modulators. Here, we have investigated whether lipids and related compounds interfered with the binding of the sulphonylurea, glibenclamide (GBC) and of the opener, N‐cyano‐N′‐(1,1‐dimethylpropyl)‐N″‐3‐pyridylguanidine (P1075), to the SUR subtypes.
Lipids (100–300 μM) inhibited binding of [3H]GBC and [3H]P1075 to SUR subtypes in the rank order OCoA>dioleylglycerol‐succinyl‐nitriloacetic acid (DOGS‐NTA)>oleate>malonyl‐CoA>PIP2.
OCoA inhibited radioligand binding to SUR completely, with IC50 values ranging from 6 to 44 μM. Inhibition was reversed by increasing the concentration of the radioligands in agreement with an essentially competitive mechanism. MgATP and coexpression with Kir6.2 decreased the potency of OCoA.
DOGS‐NTA inhibited radioligand binding to SUR by 40–88%, with IC50 values ranging from 38 to 120 μM.
Poly‐lysine increased radioligand binding to SUR by up to 30% but did not affect much the inhibition of ligand binding by OCoA and DOGS‐NTA.
Radioligand binding to SUR2A but not to the other SUR subtypes was slightly (10–20%) stimulated by lipids at concentrations ∼10 × lower than required for inhibition.
The data show that certain lipids, at high concentrations, interact with SUR and inhibit the binding of GBC and P1075; with SUR2A, a modest stimulation of ligand binding precedes inhibition. Regarding KATP channel activity, these effects will be overruled by the interaction of the lipids with Kir6.2 at lower (physiological) concentrations. They are, however, of pharmacological importance and must be taken into account if high concentrations of these compounds (e.g. OCoA>10 μM) are used to interfere with the action of sulphonylureas and openers on KATP channel activity.

British Journal of Pharmacology (2005) 145, 907–915. doi:10.1038/sj.bjp.0706252
Bradykinin‐induced, endothelium‐dependent responses in porcine coronary arteries: involvement of potassium channel activation and epoxyeicosatrienoic acids
Authors: Weston Arthur H , Félétou Michel , Vanhoutte Paul M , Falck John R , Campbell William B , Edwards Gillian 
Published: May 2005

In coronary arteries, bradykinin opens endothelial intermediate‐ and small‐conductance Ca2+‐sensitive K+ channels (IKCa and SKCa) and, additionally, releases epoxyeicosatrienoic acids (EETs) from the endothelium. To clarify the involvement of these pathways in endothelium‐dependent myocyte hyperpolarization, bradykinin‐induced electrical changes in endothelial cells and myocytes of porcine coronary arteries (following nitric oxide (NO) synthase and cyclooxygenase inhibition) were measured using sharp microelectrodes.
Hyperpolarization of endothelial cells by bradykinin (27.0±0.9 mV, n=4) was partially inhibited (74%) by blockade of IKCa and SKCa channels using 10 μM TRAM‐39 (2‐(2‐chlorophenyl)‐2,2‐diphenylacetonitrile) plus 100 nM apamin (leaving an iberiotoxin‐sensitive component), whereas the response to substance P was abolished.
After gap junction blockade with HEPES, (N‐(2‐hydroxyethyl)piperazine‐N′‐(2‐ethanesulphonic acid)) hyperpolarization of the endothelium by 100 nM bradykinin was abolished by TRAM‐39 plus apamin, whereas myocyte hyperpolarization still occurred (12.9±1.0 mV, n=4). The residual hyperpolarizations to 100 nM bradykinin were antagonized by the EET antagonist, 14,15‐EEZE (14,15‐epoxyeicosa‐5(Z)‐enoic acid) (10 μM), and abolished by iberiotoxin. Bradykinin‐induced myocyte hyperpolarizations were also reduced by 14,15‐EEZE‐mSI (14,15‐EEZE‐methylsulfonylimide) (5,6‐ and 14,15‐EET antagonist), whereas those to exogenous 11,12‐EET were unaffected.
These data show that bradykinin‐induced hyperpolarization of endothelial cells (due to the opening of IKCa and SKCa channels) is electrotonically transferred to the myocytes via gap junctions. Bradykinin (but not substance P) also hyperpolarizes myocytes by a mechanism (independent of endothelial cell hyperpolarization) which involves endothelial cell production of EETs (most likely 14,15‐ and/or 11,12‐EET). These open endothelial IKCa and SKCa channels and also activate large‐conductance calcium‐sensitive K+ channels (BKCa) on the surrounding myocytes.

British Journal of Pharmacology (2005) 145, 775–784. doi:10.1038/sj.bjp.0706256