Aldolase A deficiency: Report of new cases and literature review.

Aldolase A (ALDOA), is the predominant isoform of aldolase in skeletal muscle and erythrocytes that catalyzes the reversibleconversion of fructose-1,6-bisphosphate to glyceraldehyde 3-phosphate. Autosomal recessive mutations in ALDOA, are extremely rare and cause hemolytic anemia and/or recurrent episodes of rhabdomyolysis, usually precipitated by fever. In this report we describe, clinical, laboratory and genetic data of two novel unrelated patients harboring mutations in the ALDOA gene who presented with episodic rhabdomyolysis, we review all previously published cases and discuss the most valuable features for diagnosis of this rare disorder.

Evaluation of LOCI technology-based thyroid blood tests on the Dimension Vista analyzer.

OBJECTIVES: To assess the performance of thyroid-stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) determinations by luminescent oxygen channeling immunoassay (LOCI) technology on the Dimension Vista analyzer (Siemens Healthcare Diagnostics). DESIGN & METHODS: We assessed 1) functional sensitivity for TSH (FSe-TSH), and intra- and inter-assay variations for TSH, FT4 and FT3 on Vista; 2) comparisons of serum and heparin-treated plasma on Vista; 3) comparisons of a) plasma TSH by Vista versus electrochemiluminescence (ECLIA) on Roche Modular analyzer, and b) plasma FT4 and FT3 by Vista versus Immunotech-Beckman radioimmunoassay (RIA); and 4) association of albumin and prealbumin levels with free thyroid hormone concentrations on Vista. RESULTS: 1) FSe-TSH concentration was below 0.005 mIU/L. Maximum intra-assay CVs (2.1%, 1.4%, 5.2%) and inter-assay CVs (16.5%, 5.1%, 5.8%) were good for TSH, FT4 and FT3 respectively. 2) Heparin-treated plasma samples consistently gave slightly higher values than serum for TSH, FT4 and FT3. 3) Passing-Bablok regression gave: TSH: [LOCI]=0.91[ECLIA]-0.08 (concordance correlation coefficient ρ(c)=0.95); FT4: [LOCI]=1.05[RIA]-1.55 (ρ(c)=0.80); and FT3: [LOCI]=1.05[RIA]-0.06 (ρ(c)=0.81). 4) Both serum albumin and prealbumin concentrations were positively associated with FT3 levels and negatively associated with FT4 levels in patients. CONCLUSION: LOCI is accurate for TSH, FT4 and FT3 analysis. Despite a slight significant bias compared to ECLIA, LOCI is precise for TSH and fulfills the third-generation criteria. However, the poor concordance between LOCI and RIA for FT4 and FT3, and the dependence of these hormones on binding proteins require further investigation.

[Medical treatments of hyperactive child: about the new pharmaceutical forms of methylphenidate marketed in France]. / Traitements médicaux de l'enfant hyperactif: à propos des deux nouvelles formes de méthylphénidate commercialisées en France.

Multimodal treatment of hyperactive child includes psychostimulant medication, methylphenidate (MPH) marketed in France in its short-acting form since about ten years. We report our clinical experience about the first fifty methylphenidate responders who received one of the two sustained-release forms available since summer 2004, tablets of oros-methyphenidate (Concerta LP) or microgranule-filled capsules (Ritaline LP).

[A very high level in a cardiac troponin I assay]. / Une valeur de troponine I cardiaque particulièrement élevée.

Cardiac troponin I (TnIc) is a very sensitive and also a specific marker of myocardial injuries. We report here, the clinical case of a patient with a particularly important and brutal increase of the troponin during a myocardial infarction. A 64-year-old man was admitted to hospital. He had a myocardial infarction associated to a cardiac necrosis and important cytolysis. The troponin assay was normal when the patient was hospitalized. The angioplasty coronary reperfusion brought about a massive troponin Ic release in systemic circulation: the assay made 10 hours after the appearance of the symptoms shows us an exceptional TnIc concentration that is greater than 4000 microg/L (baseline: 1,5 microg/L). This might be the highest value ever reported.

5-lipoxygenase expression and activity in aorta from streptozotocin-induced diabetic rats.

We previously reported an activation of the 5-lipoxygenase pathway in aorta from streptozotocin-induced diabetic rats. The aim of this study was to investigate whether this activation was associated with an increased expression of 5-lipoxygenase, an increased cysteinyl leukotriene (CysLT) production in response to arachidonic acid or calcium ionophore A23187 and/or a hypersensitivity of the aorta to CysLTs in streptozotocin-induced diabetic rats. In aorta from diabetic and control rats, reverse transcriptase-PCR and western blot analysis with a specific 5-lipoxygenase antibody provided evidence for the presence of 5-lipoxygenase in aorta. However, the expression of 5-lipoxygenase was not significantly different between diabetic and control rats. Challenge by A23187 (10 microM) and arachidonic acid (10 microM and 0.1 mM) with or without A23187 (10 micromol/l) induced a significant increase of CysLT release (measured by enzyme immunoassay) that was in the same range in aorta from control and diabetic rats. In contrast, aortas from diabetic rats showed a greater sensitivity to LTC4 and LTD4 contractile effects. These data suggested that the activation of the 5-lipoxygenase pathway previously reported in streptozotocin-induced diabetic rats could be explained by an augmented sensitivity to CysLTs of the diabetic aorta.

Protein delivery by Pseudomonas type III secretion system: Ex vivo complementation of p67(phox)-deficient chronic granulomatous disease.

Bacterial type III secretion system drives the translocation of virulence factors into the cystosol of host target cells. In phagocytes and in Epstein-Barr virus immortalized B lymphocytes, NADPH oxidase generates O(-2) through an electron transfer chain the activity of which depends on the assembly of three, p67(phox), p47(phox) and p40(phox) cytosolic activating factors with Rac 1/2 and a membrane redox component, cytochrome b(558). In p67(phox) deficient chronic granulomatous disease (CGD) patients, p67-phox is missing and NADPH oxidase activity is abolished. ExoS is a virulence factor of Pseudomonas aeruginosa which is secreted via the type III secretion system: it was fused with p67(phox). Pseudomonas aeruginosa synthesized and translocated the hybrid ExoS-p67(phox) fusion protein into the cytosol of B lymphocytes via the type III secretion system. Purified ExoS-p67(phox) hybrid protein was as efficient as normal recombinant p67(phox) in cell-free reconstitution of NADPH oxidase activity. Therefore, ExoS-p67(phox) was transferred via the type III secretion system of Pseudomonas aeruginosa into the cytosol of B lymphocytes from a p67(phox)-deficient CGD patient and functionally reconstituted NADPH oxidase activity. In the complementation process, ExoS acted as a molecular courier for protein delivery: the reconstitution of an active NADPH oxidase complex suggests type III secretion system to be a new approach for cellular therapy.

P67-phox-mediated NADPH oxidase assembly: imaging of cytochrome b558 liposomes by atomic force microscopy.

NADPH oxidase activity depends on the assembly of the cytosolic activating factors, p67-phox, p47-phox, p40-phox, and Rac with cytochrome b(558). The transition from an inactive to an active oxidase complex induces the transfer of electrons from NADPH to oxygen through cytochrome b(558). The assembly of oxidase complex was studied in vitro after reconstitution in a heterologous cell-free assay by using true noncontact mode atomic force microscopy. Cytochrome b(558) was purified from neutrophils and Epstein-Barr virus-immortalized B lymphocytes and incorporated into liposomes. The effect of protein glycosylation on liposome size and oxidase activity was investigated. The liposomes containing the native hemoprotein purified from neutrophils had a diameter of 146 nm, whereas after deglycosylation, the diameter was reduced to 68 nm, although oxidase activity was similar in both cases. Native cytochrome b(558) was used after purification in reconstitution experiments to investigate the topography of NADPH oxidase once it was assembled. For the first time, atomic force microscopy illustrated conformational changes of cytochrome b(558) during the transition from the inactive to the active state of oxidase; height measurements allow the determination of a size of 4 nm for the assembled complex. In the processes that were studied, p67-phox displayed a critical function; it was shown to be involved in both assembly and activation of oxidase complex while p47-phox proceeded as a positive effector and increased the affinity of p67-phox with cytochrome b(558), and p40-phox stabilizes the resting state. The results suggest that although an oligomeric structure of oxidase machinery has not been demonstrated, allosteric regulation mechanisms may be proposed.

Complementation of NADPH oxidase in p67-phox-deficient CGD patients p67-phox/p40-phox interaction.

Chronic granulomatous disease (CGD) is due to a functional defect of the O2- generating NADPH oxidase of phagocytes. Epstein-Barr-virus-immortalized B lymphocytes express all the constituents of oxidase with activity 100 times less than that of neutrophils. As in neutrophils, oxidase activity of Epstein-Barr-virus-immortalized B lymphocytes was shown to be defective in the different forms of CGD; these cells were used as a model for the complementation studies of two p67-phox-deficient CGD patients. Reconstitution of oxidase activity was performed in vitro by using a heterologous cell-free assay consisting of membrane-suspended or solubilized and purified cytochrome b558 that was associated with cytosol or with the isolated cytosolic-activating factors (p67-phox, p47-phox, p40-phox) from healthy or CGD patients. In p67-phox-deficient CGD patients, two cytosolic factors are deficient or missing: p67-phox and p40-phox. Not more than 20% of oxidase activity was recovered by complementing the cytosol of p67-phox-deficient patients with recombinant p67-phox. On the contrary, a complete restoration of oxidase activity was observed when, instead of cytosol, the cytosolic factors were added in the cell-free assay after isolation in combination with cytochrome b558 purified from neutrophil membrane. Moreover, the simultaneous addition of recombinant p67-phox and recombinant p40-phox reversed the previous complementation in a p40-phox dose-dependent process. These results suggest that in the reconstitution of oxidase activity, p67-phox is the limiting factor; the efficiency of complementation depends on the membrane tissue and the cytosolic environment. In vitro, the transition from the resting to the activated state of oxidase, which results from assembling, requires the dissociation of p40-phox from p67-phox for efficient oxidase activity. In the process, p40-phox could function as a negative regulatory factor and stabilize the resting state.

P40phox associates with the neutrophil Triton X-100-insoluble cytoskeletal fraction and PMA-activated membrane skeleton: a comparative study with P67phox and P47phox.

NADPH oxidase is an O2*- -generating enzyme found in phagocytes such as neutrophils. It is composed of a membrane-bound cytochrome b, the cytosolic proteins p67phox, p47phox, p40phox, and the G-protein p21rac. The system is dormant in resting cells but acquires catalytic activity on exposure to appropriate stimuli. Cytochrome b, p67phox, p47phox, and rac2 associate with the cytoskeleton and membrane skeleton of activated neutrophils. It is not known whether p40phox associates with the cytoskeleton. The purpose of this study was to analyze the subcellular distribution of p40phox. When resting neutrophils were lysed in Triton X-100 or octyl glucoside buffer and separated into detergent-soluble and detergent-insoluble fractions, p40phox and p67phox were mainly associated with the detergent-insoluble fraction (defined as the cytoskeleton), whereas p47phox was mainly found in the soluble fraction. Neutrophil activation by phorbol myristate acetate (PMA) induced p47phox translocation to the cytoskeleton but did not affect the distribution of p40phox or p67phox. Using immunofluorescence confocal microscopy, we found that p40phox colocalized with filamentous actin. In neutrophils from a p67phox-deficient patient with detectable p40phox, p40phox associated with the cytoskeleton only after activation by PMA. A complex containing the three proteins was isolated from the cytoskeleton of activated neutrophils. When activated membranes were treated with Triton X-100 buffer, p40phox, p47phox, and p67phox were found in the membrane skeleton enriched in NADPH-oxidase activity; some p40phox and p47phox was found in the soluble membrane fraction, but no p67phox was detected. These findings show that p40phox, like p67phox and p47phox, binds to the cytoskeleton and membrane skeleton. In addition, p40phox can dissociate from p67phox in activated membranes.

Biochemical and immunochemical properties of B lymphocyte cytochrome b558.

Like neutrophils, Epstein-Barr virus (EBV)-immortalized B lymphocytes express all constituents of the NADPH oxidase complex necessary to generate superoxide anion O2-. The NADPH oxidase activity in EBV-B lymphocytes is only 5% of that measured in neutrophils upon PMA stimulation. Cytochrome b558 is the sole redox membrane component of NADPH oxidase; it is the protein core around which cytosolic factors assemble in order to mediate oxidase activity. In the present study, we have compared the structural and functional properties of cytochrome b558 from EBV-B lymphocytes and neutrophils. Cytochrome b558 from EBV-B lymphocyte plasma membrane, like that from neutrophils, is characterized by a heterodimeric structure with a highly glycosylated beta subunit, known as gp91-phox. While the amount of cytochrome b558 recovered after purification from EBV-B lymphocytes (approximately 0.24 nmol from 1010 cells) was low compared to that recovered from neutrophils (approximately 10 nmol), the biochemical properties of purified cytochrome b558 from both EBV-B lymphocytes and neutrophils were quite similar with respect to their differential spectra, redox potential, and FAD binding site. Once cytochrome b558 was extracted from the EBV-B lymphocyte membrane, it was able to mediate, in a reconstituted system of O2- production the same oxidase turnover as that found for cytochrome b558 extracted from neutrophils. A comparison between membrane bound and soluble cytochrome b558 suggested that the weak oxidase activity measured in intact EBV-B cells might be the result not only of the small amount of expressed cytochrome b558, but also of a defect of the activation process in lymphocyte membrane.