Metahemoglobinemia grave de origen desconocido: respuesta al tratamiento con ácido ascórbico

La metahemoglobina es una forma oxidada de la hemoglobinaque en un valor mayor a 1% en adultos y a 2% en lactantes, que genera anemia funcional e hipoxia tisular. Puede ser adquirida o congénita. La forma adquirida es más frecuente y suele ocurrir cuando se sobrepasa los mecanismos reductores de protección. El azul de metileno es el antídoto de primera elección. En caso de no contar con este, debe considerarse el uso de ácido ascórbico. La instauración de un tratamiento rápido y eficaz disminuye los efectos potencialmente fatales. Reportamos el caso de un paciente de 2 años que ingresa a la guardia pediátrica con cianosis generalizada refractaria a la oxigenoterapia.Methemoglobin is an oxidized form of hemoglobin that in a value greater than 1% in adults and 2% in infants generates functional anemia and tissue hypoxia. It can be acquired or congenital. The acquired form is more frequent and usually occurs when the protective reducing mechanisms are exceeded. Methylene blue is the first-line antidote. If such is not available, the use of ascorbic acid should be considered. Choosing a fast and effective treatment decreases the potentially fatal effects. We report the case of a 2-year-old patient who enters the pediatric ward with generalized cyanosis refractory to oxygen therapy

Validación de un método por cromatografía líquida de alta resolución (HPLC) para la determinación de ivabradina en comprimidos

RESUMENSe presentan los resultados obtenidos en la validación de un método analítico por cromatografía líquida de alta resolución, para la determinación de ivabradina en comprimidos, el cual se diseñó para identificar y cuantificar a dicho analito, con la utilización de una columna RP-18 (150 x 4,6 mm) 5 m y un detector UV-Vis a una λ: 285 nm. Dicho método se empleará para el control de la calidad y estabilidad de ivabradina comprimidos. El método fue validado siguiendo una metodología de trabajo de acuerdo a los lineamientos de la Conferencia Internacional sobre Armonización de Requisitos Técnicos para el Registro de Medicamentos de uso humano, Validación de procedimientos analíticos (ICH Q2), obteniendo los siguientes resultados: linealidad (r2 = 0,999), precisión Desviación estándar relativa (DSR) = 0,67 % para comprimidos del lote piloto y DSR=0,31% para comprimidos del lote comercial) y exactitud recuperación media=100,2%, demostrando de esta manera que el método propuesto es aplicable a la dosificación de ivabradina en comprimidos, tanto en el análisis del producto terminado cómo en los estudios de estabilidad

Dusty core disease (DuCD): expanding morphological spectrum of RYR1 recessive myopathies

Several morphological phenotypes have been associated to RYR1-recessive myopathies. We recharacterized the RYR1-recessive morphological spectrum by a large monocentric study performed on 54 muscle biopsies from a large cohort of 48 genetically confirmed patients, using histoenzymology, immunohistochemistry, and ultrastructural studies. We also analysed the level of RyR1 expression in patients' muscle biopsies. We defined "dusty cores" the irregular areas of myofibrillar disorganisation characterised by a reddish-purple granular material deposition with uneven oxidative stain and devoid of ATPase activity, which represent the characteristic lesion in muscle biopsy in 54% of patients. We named Dusty Core Disease (DuCD) the corresponding entity of congenital myopathy. Dusty cores had peculiar histological and ultrastructural characteristics compared to the other core diseases. DuCD muscle biopsies also showed nuclear centralization and type1 fibre predominance. Dusty cores were not observed in other core myopathies and centronuclear myopathies. The other morphological groups in our cohort of patients were: Central Core (CCD: 21%), Core-Rod (C&R:15%) and Type1 predominance "plus" (T1P+:10%). DuCD group was associated to an earlier disease onset, a more severe clinical phenotype and a lowest level of RyR1 expression in muscle, compared to the other groups. Variants located in the bridge solenoid and the pore domains were more frequent in DuCD patients. In conclusion, DuCD is the most frequent histopathological presentation of RYR1-recessive myopathies. Dusty cores represent the unifying morphological lesion among the DuCD pathology spectrum and are the morphological hallmark for the recessive form of disease

Muscle histopathology in nebulin-related nemaline myopathy : ultrastrastructural findings correlated to disease severity and genotype

Peer reviewe

Current treatment practice of Guillain-Barré syndrome

Objective: To define the current treatment practice of Guillain-Barré syndrome (GBS). Methods: The study was based on prospective observational data from the first 1,300 patients included in the International GBS Outcome Study. We described the treatment practice of GBS in general, and for (1) severe forms (unable to walk independently), (2) no recovery after initial treatment, (3) treatment-related fluctuations, (4) mild forms (able to walk independently), and (5) variant forms including Miller Fisher syndrome, taking patient characteristics and hospital type into account. Results: We excluded 88 (7%) patients because of missing data, protocol violation, or alternative diagnosis. Patients from Bangladesh (n = 189, 15%) were described separately because 83% were not treated. IV immunoglobulin (IVIg), plasma exchange (PE), or other immunotherapy was provided in 941 (92%) of the remaining 1,023 patients, including patients with severe GBS (724/743, 97%), mild GBS (126/168, 75%), Miller Fisher syndrome (53/70, 76%), and other variants (33/40, 83%). Of 235 (32%) patients who did not improve after their initial treatment, 82 (35%) received a second immune modulatory treatment. A treatment-related fluctuation was observed in 53 (5%) of 1,023 patients, of whom 36 (68%) were re-treated with IVIg or PE. Conclusions: In current practice, patients with mild and variant forms of GBS, or with treatment-related fluctuations and treatment failures, are frequently treated, even in absence of trial data to support this choice. The variability in treatment practice can be explained in part by the lack of evidence and guidelines for effective treatment in these situations

A polymorphism of EGFR extracellular domain is associated with progression free-survival in metastatic colorectal cancer patients receiving cetuximab-based treatment

International audienceBackground: Cetuximab, a monoclonal antibody targeting Epidermal Growth Factor Receptor (EGFR), is currently used in metastatic colorectal cancer (mCRC), but predictive factors for therapeutic response are lacking. Mutational status of KRAS and EGFR, and EGFR copy number are potential determinants of cetuximab activity.Methods: We analyzed tumor tissues from 32 EGFR-positive mCRC patients receiving cetuximab/irinotecan combination and evaluable for treatment response. EGFR copy number was quantified by fluorescence in situ hybridization (FISH). KRAS exon 1 and EGFR exons coding for extracellular regions were sequenced.Results: Nine patients experienced an objective response (partial response) and 23 were considered as nonresponders (12 with stable disease and 11 with progressive disease). There was no EGFR amplification found, but high polysomy was noted in 2 patients, both of which were cetuximab responders. No EGFR mutations were found but a variant of exon 13 (R521K) was observed in 12 patients, 11 of which achieved objective response or stable disease. Progression-free and overall survivals were significantly better in patients with this EGFR exon 13 variant. KRAS mutations were found in 14 cases. While there was a trend for an increased KRAS mutation frequency in nonresponder patients (12 mutations out of 23, 52%) as compared to responder patients (2 out of 9, 22%), authentic tumor response or long-term disease stabilization was found in KRAS mutated patients.Conclusion: This preliminary study suggests that: an increase in EGFR copy number may be associated with cetuximab response but is a rare event in CRC, KRAS mutations are associated with low response rate but do not preclude any cetuximab-based combination efficacy and EGFR exon 13 variant (R521K) may predict for cetuximab benefit

Pathogenic Variants in the Myosin Chaperone UNC-45B Cause Progressive Myopathy with Eccentric Cores

The myosin-directed chaperone UNC-45B is essential for sarcomeric organization and muscle function from Caenorhabditis elegans to humans. The pathological impact of UNC-45B in muscle disease remained elusive. We report ten individuals with bi-allelic variants in UNC45B who exhibit childhood-onset progressive muscle weakness. We identified a common UNC45B variant that acts as a complex hypomorph splice variant. Purified UNC-45B mutants showed changes in folding and solubility. In situ localization studies further demonstrated reduced expression of mutant UNC-45B in muscle combined with abnormal localization away from the A-band towards the Z-disk of the sarcomere. The physiological relevance of these observations was investigated in C. elegans by transgenic expression of conserved UNC-45 missense variants, which showed impaired myosin binding for one and defective muscle function for three. Together, our results demonstrate that UNC-45B impairment manifests as a chaperonopathy with progressive muscle pathology, which discovers the previously unknown conserved role of UNC-45B in myofibrillar organization