Hyper-IgM (HIGM) syndrome is a heterogeneous group of disorders characterized by normal or elevated serum IgM levels associated with absent or decreased IgG, IgA and IgE. Here we summarize data from the HIGM syndrome Registry of the Latin American Society for Immunodeficiencies (LASID). Of the 58 patients from 51 families reported to the registry with the clinical phenotype of HIGM syndrome, molecular defects were identified in 37 patients thus far. We retrospectively analyzed the clinical, immunological and molecular data from these 37 patients. CD40 ligand (CD40L) deficiency was found in 35 patients from 25 families and activation-induced cytidine deaminase (AID) deficiency in 2 unrelated patients. Five previously unreported mutations were identified in the CD40L gene (CD40LG). Respiratory tract infections, mainly pneumonia, were the most frequent clinical manifestation. Previously undescribed fungal and opportunistic infections were observed in CD40L-deficient patients but not in the two patients with AID deficiency. These include the first cases of pneumonia caused by Mycoplasma pneumoniae, Serratia marcescens or Aspergillus sp. and diarrhea caused by Microsporidium sp. or Isospora belli. Except for four CD40L-deficient patients who died from complications of presumptive central nervous system infections or sepsis, all patients reported in this study are alive. Four CD40L-deficient patients underwent successful bone marrow transplantation. This report characterizes the clinical and genetic spectrum of HIGM syndrome in Latin America and expands the understanding of the genotype and phenotype of this syndrome in tropical areas.

A new three-scale model to describe the coupling between pH-dependent flows and transient ion transport including sorption phenomena in kaolinite clays is proposed. The kaolinite is characterized by three separate nano-micro and macroscopic length scales. The (micro)-scale consists of micro-pores saturated by an aqueous solution containing four monovalent ionic species (Na + , H + , Cl − , OH − ) and charged solid particles surrounded by thin electrical double layers. The movement of the ions is governed by the Nernst-Planck equations and the influence of the double layers upon the flow is dictated by the Helmholtz-Smoluchowski slip boundary condition in the tangential velocity. In addition, sorption interface conditions for ion transport are postulated in the sense of Auriault and Lewandowska (Eur. J. Mech. A 15: 1996) to capture the immobilization of the ions in the electrical double layer and on particle surface due to protonation/deprotonation reactions. The intensity of sorption relative to diffusion effects is quantified by the Damköhler number, whose order of magnitude is estimated by invoking the nanoscopic modeling of the thin EDL based on Poisson-Boltzmann problem for the local electric potential coupled with a non-linear surface charge density with constitutive law dictated by the protonation/deprotonation reactions. The two-scale nano/micro model including sorption and slip boundary condition is homogenized to the core scale leading to a derivation of macroscopic governing equations.

A new three-scale model to describe the coupling between electro-chemistry and hydrodynamics in non-swelling kaolinite clays in steady-state conditions is proposed. The medium is characterized by three separate nano-micro and macroscopic length scales. At the pore (micro)-scale the portrait of the clay consists of micropores saturated by an aqueous solution containing four monovalent ions (Na + , H + , Cl -, OH -) and charged solid particles surrounded by thin electrical double layers. The movement of the ions is governed by the Nernst-Planck equations and the influence of the double layers upon the hydrodynamics is modeled by a slip boundary condition in the tangential velocity governed by the Stokes problem. To capture the correct form of the interface condition we invoke the nanoscopic modeling of the thin electrical double layer based on Poisson-Boltzmann problem with varying surface charge density ruled by the protonation/ deprotonation reactions which occur at the surface of the particles. The two-scale nano/micro model is homogenized to the macroscale leading to a precise derivation of effective governing equations. The macroscopic model is discretized by the finite volume method and applied to numerically simulate desalination of a clay sample induced by an external electrical field generated by the placement of electrodes. Numerical results indicate strong pHdependence of the electrokinetics.