Instability of the mitochondrial alanyl-tRNA synthetase underlies fatal infantile-onset cardiomyopathy

Recessively inherited variants in AARS2 (NM_020745.2) encoding mitochondrial alanyl-tRNA synthetase (mt-AlaRS) were first described in patients presenting with fatal infantile cardiomyopathy and multiple oxidative phosphorylation defects. To date, all described patients with AARS2-related fatal infantile cardiomyopathy are united by either a homozygous or compound heterozygous c.1774C>T (p.Arg592Trp) missense founder mutation that is absent in patients with other AARS2-related phenotypes. We describe the clinical, biochemical and molecular investigations of two unrelated boys presenting with fatal infantile cardiomyopathy, lactic acidosis and respiratory failure. Oxidative histochemistry showed cytochrome c oxidase-deficient fibres in skeletal and cardiac muscle. Biochemical studies showed markedly decreased activities of mitochondrial respiratory chain complexes I and IV with a mild decrease of complex III activity in skeletal and cardiac muscle. Using next-generation sequencing, we identified a c.1738C>T (p.Arg580Trp) AARS2 variant shared by both patients that was in trans with a loss-of-function heterozygous AARS2 variant; a c.1008dupT (p.Asp337*) nonsense variant or an intragenic deletion encompassing AARS2 exons 5-7. Interestingly, our patients did not harbour the p.Arg592Trp AARS2 founder mutation. In silico modelling of the p.Arg580Trp substitution suggested a deleterious impact on protein stability and folding. We confirmed markedly decreased mt-AlaRS protein levels in patient fibroblasts, skeletal and cardiac muscle, although mitochondrial protein synthesis defects were confined to skeletal and cardiac muscle. In vitro data showed that the p.Arg580Trp variant had a minimal effect on activation, aminoacylation or misaminoacylation activities relative to wild-type mt-AlaRS, demonstrating that instability of mt-AlaRS is the biological mechanism underlying the fatal cardiomyopathy phenotype in our patients.Peer reviewe

808 nm driven Nd 3+

The in vivo biological applications of upconversion nanoparticles (UCNPs) prefer excitation at 700-850 nm, instead of 980 nm, due to the absorption of water. Recent approaches in constructing robust Nd3+ doped UCNPs with 808 nm excitation properties rely on a thick Nd3+ sensitized shell. However, for the very important and popular Frster resonance energy transfer (FRET)-based applications, such as photodynamic therapy (PDT) or switchable biosensors, this type of structure has restrictions resulting in a poor energy transfer. In this work, we have designed a NaYF4:Yb/Ho@NaYF4:Nd@NaYF4 core-shell-shell nanostructure. We have proven that this optimal structure balances the robustness of the upconversion emission and the FRET efficiency for FRET-based bioapplications. A proof of the concept was demonstrated for photodynamic therapy and simultaneous fluorescence imaging of HeLa cells triggered by 808 nm light, where low heating and a high PDT efficacy were achieved

Early onset of nephrogenic diabetes insipidus due to fabry disease in a child with GLA N215S mutation: Case report and literature review

Background: Fabry disease (FD) is a rare X-linked lysosomal storage disorder. Renal involvement in FD is characterized by proteinuria and progressive renal decline. Reports on FD with nephrogenic diabetes insipidus as the initial manifestation are rare. In this paper, we report a pediatric case with an N215S variant. Results: A boy with an onset of polydipsia and polyuria at approximately 4 years of age was diagnosed with nephrogenic diabetes insipidus. Whole-exome sequencing showed a GLA N215S variation with no secondary cause of diabetes insipidus. No family history of polydipsia or polyuria was reported; however, the patient's maternal grandmother and her two younger brothers had hypertrophic cardiomyopathy. Both brothers required surgery due to severe cardiac involvement, and the youngest brother died of heart disease at the age of 50 years. The patient's polydipsia and polyuria worsened over the next 7 years. Serum sodium was normal, but the patient required high-dose potassium chloride to maintain normal serum potassium levels. His physical and intellectual development was normal, with no common complications of nephrogenic diabetes insipidus, such as anemia, malnutrition, vomiting, high fever, or convulsions. Dried blood spot testing showed α-galactosidase A (α-gal A) activity of 0.6 μmol/L/h and a Lyso-GL-3 level of 7.01 ng/ml. The patient developed mild proteinuria and mild myocardial hypertrophy. Renal biopsy showed myeloid bodies and zebra bodies. After more than 1 year of ERT, his urine specific gravity increased to 1.005–1.008, which was a new sign reflecting the efficacy of ERT, although urine output was maintained at 3–5 ml/kg/hour. We will continue to monitor the patient's renal tubular function and urine output. Conclusions: Nephrogenic diabetes insipidus may be the initial manifestation in children with FD and/or N215S variation. In FD, the same mutation in a family may present a completely different phenotype

The displacement and strain field of three-dimensional rheologic model of earthquake preparation

Based on the three-dimensional elastic inclusion model proposed by Dobrovolskii, we developed a rheological inclusion model to study earthquake preparation processes. By using the Corresponding Principle in the theory of rheologic mechanics, we derived the analytic expressions of viscoelastic displacement U(r, t) , V(r, t) and W(r, t), normal strains epsilon(xx) (r, t), epsilon(yy) (r, t) and epsilon(zz) (r, t) and the bulk strain theta (r, t) at an arbitrary point (x, y, z) in three directions of X axis, Y axis and Z axis produced by a three-dimensional inclusion in the semi-infinite rheologic medium defined by the standard linear rheologic model. Subsequent to the spatial-temporal variation of bulk strain being computed on the ground produced by such a spherical rheologic inclusion, interesting results are obtained, suggesting that the bulk strain produced by a hard inclusion change with time according to three stages (alpha, beta, gamma) with different characteristics, similar to that of geodetic deformation observations, but different with the results of a soft inclusion. These theoretical results can be used to explain the characteristics of spatial-temporal evolution, patterns, quadrant-distribution of earthquake precursors, the changeability, spontaneity and complexity of short-term and imminent-term precursors. It offers a theoretical base to build physical models for earthquake precursors and to predict the earthquakes