Genetic analysis of patients with fructose-1,6-bisphosphatase deficiency.

INTRODUCTION: Fructose-1,6-bisphosphatase deficiency (FBPase deficiency) is a rare inborn error of metabolism that affects gluconeogenesis. Ketotic hypoglycemia is the main symptom and can occur at any age, usually after long periods of fasting or during illness. The diagnosis may be achieved by measurement of the enzyme activity in a liver sample, but FBP1 analysis has become the most common approach. AIM: To characterize the genotype of Southern Brazilian FBPase-deficient patients. METHODOLOGY: The FBP1 gene of six unrelated patients (one had consanguineous parents) with previous diagnoses of FBPase deficiency (enzymatic, pts A, B, D, E; genetic through Next-Generation Sequencing-NGS, pt F; enzymatic and Sanger sequencing, pt C) was first analyzed through NGS. Pathogenic variants found in NGS were confirmed by Sanger sequencing. The pathogenicity of novel missense variants was evaluated through in silico analysis. RESULTS: Five patients (pt A, B, D, E, F) had their genotype identified by NGS, all of them being homozygous. In Pt C, NGS detected only one pathogenic variant. Among the 11 alleles analyzed, only three variants were found, two being novel: c.958G > A and c.986T > C. In silico analysis indicated the pathogenicity of both variants. Interestingly, the three variants seem to be linked to specific haplotypes, indicating that an endogamy effect may be acting on these alleles in the population of Southern Brazil. CONCLUSIONS: Our data suggest that NGS is a good tool for the diagnosis of FBPase deficiency. Variants c.958G > A and c.986T > C are the most prevalent variants in the country.

Expression of fructose 1,6-bisphosphatase and phosphofructokinase is induced in hepatopancreas of the white shrimp Litopenaeus vannamei by hypoxia.

Marine organisms are exposed to hypoxia in natural ecosystems and during farming. In these circumstances marine shrimp survive and synthesize ATP by anaerobic metabolism. Phosphofructokinase (PFK) and fructose 1,6-bisphosphatase (FBP) are key enzymes in carbohydrate metabolism. Here we report the cDNA of FBP from the shrimp Litopenaeus vannamei hepatopancreas and expression of PFK and FBP under normoxia and hypoxia. Hypoxia induces PFK and FBP expression in hepatopancreas but not in gills and muscle. Induction in hepatopancreas of the glycolytic and gluconeogenic key enzymes, PFK and FBP, suggests that PFK could be a key factor for increasing anaerobic rate, while FBP is probably involved in the activation of gluconeogenesis or the pentose-phosphates pathway during hypoxia in the highly active metabolism of hepatopancreas.

Fructose 1-phosphate is the one and only physiological effector of the Cra (FruR) regulator of Pseudomonas putida.

Fructose-1-phosphate (F1P) is the preferred effector of the catabolite repressor/activator (Cra) protein of the soil bacterium Pseudomonas putida but its ability to bind other metabolic intermediates in vivo is unclear. The Cra protein of this microorganism (Cra(PP)) was submitted to mobility shift assays with target DNA sequences (the PfruB promoter) and candidate effectors fructose-1,6-bisphosphate (FBP), glucose 6-phosphate (G6P), and fructose-6-phosphate (F6P). 1 mM F1P was sufficient to release most of the Cra protein from its operators but more than 10 mM of FBP or G6P was required to free the same complex. However, isothermal titration microcalorimetry failed to expose any specific interaction between Cra(PP) and FBP or G6P. To solve this paradox, transcriptional activity of a PfruB-lacZ fusion was measured in wild-type and ΔfruB cells growing on substrates that change the intracellular concentrations of F1P and FBP. The data indicated that PfruB activity was stimulated by fructose but not by glucose or succinate. This suggested that Cra(PP) represses expression in vivo of the cognate fruBKA operon in a fashion dependent just on F1P, ruling out any other physiological effector. Molecular docking and dynamic simulations of the Cra-agonist interaction indicated that both metabolites can bind the repressor, but the breach in the relative affinity of Cra(PP) for F1P vs FBP is three orders of magnitude larger than the equivalent distance in the Escherichia coli protein. This assigns the Cra protein of P. putida the sole role of transducing the presence of fructose in the medium into a variety of direct and indirect physiological responses.

Ventilación diferencial en patología pulmonar bilateral con distinta fisiopatología / Differential ventilation in bilateral pulmonary pathology with different physiopathology

En este caso clínico presentamos un paciente con diagnóstico de Enfermedad Pulmonar Obstructiva Crónica internado en paro respiratorio secundario a neumotórax derecho espontáneo hipertensivo. Ante hipoxemia refractaria por persistencia de neumotórax derecho, con fístula broncopleural, eventos repetidos de atelectasia izquierda con dificultades para resolver mediante ventilación convencional, fibroncoscopia y kinesioterapia, se decide aplicar ventilación pulmonar diferencial (VPD). La VPD fue aplicada con dos ventiladores no sincronizados y PEEP diferencial. El destete fue progresivo, volviendo a modos convencionales con tubo un lumen y traqueostomia. Se realizó extubación exitosa, egresando de la Terapia Intensiva al día 33 del ingreso y del hospital al día 48. En el seguimiento a 7 meses recuperó su capacidad funcional previa y se reintegró a sus tareas laborales habituales. La VPD puede ser útil en pacientes seleccionados cuando la ventilación convencional no obtiene una respuesta adecuada en el adecuado sostenimiento de la ventilación pulmonar.(AU)