ICOS expression is required for maintenance but not the formation of germinal centers in the spleen in response to P. yoelii infection.

Inducible T cell co-stimulator (ICOS) plays a key role in the differentiation and maintenance of follicular helper T (Tfh) cells and thus germinal center (GC) formation. Previously, our lab showed in a Plasmodium chabaudi infection model that Icos -/- mice were significantly impaired in their ability to form GCs despite a persistent infection and thus a continued antigen (Ag) load. Here, we show that resolution of a primary infection with P. yoelii , was delayed in Icos -/- mice. This phenotype was associated with a reduction in the accumulation of Tfh-like and GC Tfh cells and an early deficiency in Ag-specific antibody (Ab) production. However, Icos -/- mice could form GCs, though they were less frequent in number than in wild-type (WT) mice. Nonetheless, the Ag-specific Abs from Icos -/- mice lacked signs of affinity maturation, suggesting functional defects associated with these GCs. Eventually, these GC structures dissipated more rapidly in Icos -/- mice than in WT mice. Moreover, the ability of Icos -/- mice to form these GC structures is not reliant on the high Ag load associated with P. yoelii infections, as GC formation was preserved in Icos -/- mice treated with atovaquone. Finally, mice were unable to form secondary GCs in the absence of ICOS after re-challenge. Overall, these data demonstrate the necessity of ICOS in the maintenance of Tfh cells, the formation and maintenance of sufficient numbers of functioning GCs, and the ability to generate new GC structures after re-infection with P. yoelii .

A safe procedure? The unusual case of a fatal airway obstruction by silicone during the production process of a tracheostomal epithesis in a 13-year-old boy

A tracheostomal epithesis is a plastic prosthesis that serves for sealing a tracheostoma and ensuring the position of the tracheostomy tube. The production of a tracheostomal epithesis requires an impression of the tracheostoma. To this end, silicone impression material is applied by an anaplastologist in and around the tracheostomal region, including the trachea. The blocked cuff of the tracheostomy tube serves to prevent aspiration of the material. We report on a 13-year-old boy who died during this procedure because the lower airways were obstructed with cured silicone. Forensic autopsy confirmed asphyctic suffocation as cause of death. Forensic physical investigation of the tracheostomy tube and its cuff revealed no structural or functional defects. Yet, the investigation results prove that the viscous silicone must have passed the cuff. To conclude, this case report demonstrates that the production of an impression of a tracheostoma is a procedure with a potentially lethal outcome. Hence, professional guidelines, including clear safety precautions, are urgently needed.

Drugs Used During Pregnancy and Lactation

In time of pregnancy, drugs are often required to treat certain disorders. In general potential benefit outweighs known risks, drugs may be considered for treatment of disorders during pregnancy. All maternal drugs not cross the planceta to the fetus. Some drugs that cross the placenta may have a direct toxic effect or teratogenic effect . Understanding the risks of drugs use in pregnancy has lagged being the advances in other areas of pharmacotherapy. The adverse developmental effects of pharmaceutical products are recognized to include not only mal formation, but also growth restrictions, fetal death and functional defects in the newborn. Drug that does not cross placenta but still harm the fortus. 1979, FDA developed a system determining teratogenic risk of drugs based on animals& human studies. Divided drugs into 5 categories (A ,B, C, D, X). This article provide clinical therapeutic guidance relating drug use in pregnancy.

Mechanistic basis for SNX27-Retromer coupling to ESCPE-1 in promoting endosomal cargo recycling.

Sorting nexin-27 (SNX27)-Retromer is an endosomal sorting complex that orchestrates endosome-to-plasma membrane recycling of hundreds of internalized receptors, channels and transporters, enzymes and adhesion molecules. While SNX27-Retromer is essential for development, subtle functional defects are observed in human disease, most notably neurodegenerative and neurological disorders. Achieving a thorough mechanistic dissection of SNX27-Retromer is central to understanding endosomal sorting in health and disease. Here we combine biochemical, structural and cellular analyses to establish the mechanistic basis through which SNX27-Retromer couples to the membrane tubulating ESCPE-1 complex (Endosomal SNX-BAR sorting complex for promoting exit 1). We show that a conserved surface in the FERM (4.1/ezrin/radixin/moesin) domain of SNX27 directly binds acidic-Asp-Leu-Phe (aDLF) motifs in the disordered amino-termini of the SNX1 and SNX2 subunits of ESCPE-1. This interaction hands-over SNX27-Retromer captured integral membrane proteins into ESCPE-1 tubular profiles to promote their cell surface recycling. Through phylogenetic analysis, we reveal that SNX27:Retromer:ESCPE-1 assembly evolved in a stepwise manner during the early evolution of metazoans, which reflects the increasing complexity of endosomal sorting from the ancestral opisthokont to modern animals.

ICOS expression is required for maintenance but not the formation of germinal centers in the spleen in response to P. yoelii infection.

Inducible T cell co-stimulator (ICOS) plays a key role in the differentiation and maintenance of follicular helper T (Tfh) cells and thus germinal center (GC) formation. Previously, our lab showed in a Plasmodium chabaudi infection model that Icos-/- mice did not form GCs despite a persistent infection and thus a continued antigen (Ag) load. Here, we show that resolution of a primary infection with P. yoelii, was delayed in Icos-/- mice. This phenotype was associated with a reduction in the accumulation of Tfh-like and GC Tfh cells and an early deficiency in Ag-specific antibody (Ab) production. However, Icos-/- mice maintained their ability to form GCs, though they were less frequent in number than in wild-type (WT) mice. Furthermore, while Ab production in Icos-/- mice matched that of WT mice after the infection cleared, the Abs lacked signs of affinity maturation, suggesting functional defects associated with these GCs. Eventually, these GC structures dissipated more rapidly in Icos-/-mice than in WT mice. Moreover, the ability of Icos-/- mice to form these GC structures is not reliant on the high Ag load associated with P. yoelii infections, as GC formation was preserved in Icos-/- mice treated with early with atovaquone. Finally, mice were unable to form secondary GCs in the absence of ICOS after re-challenge. Overall, these data demonstrate the necessity of ICOS in the maintenance of Tfh cells, the formation and maintenance of sufficient numbers of functioning GCs, and the ability to generate new GC structures after re-infection with P. yoelii.

Molecular mechanisms underlying enhanced hemichannel function of a cataract-associated Cx50 mutant

Connexin-50 (Cx50) is among the most frequently mutated genes associated with congenital cataracts. While most of these disease-linked variants cause loss-of-function due to misfolding or aberrant trafficking, others directly alter channel properties. The mechanistic bases for such functional defects are mostly unknown. We investigated the functional and structural properties of a cataract-linked mutant, Cx50T39R (T39R), in the Xenopus oocyte system. T39R exhibited greatly enhanced hemichannel currents with altered voltage-gating properties compared to Cx50 and induced cell death. Co-expression of mutant T39R with wild-type Cx50 (to mimic the heterozygous state) resulted in hemichannel currents whose properties were indistinguishable from those induced by T39R alone, suggesting that the mutant had a dominant effect. Co-expression with Cx46 also produced channels with altered voltage-gating properties, particularly at negative potentials. All-atom molecular dynamics simulations indicate that the R39 substitution can form multiple electrostatic salt-bridge interactions between neighboring subunits that could stabilize the open-state conformation of the N-terminal domain, while also neutralizing the voltage-sensing residue D3 as well as residue E42 which participates in loop-gating. Together, these results suggest T39R acts as a dominant gain-of-function mutation that produces leaky hemichannels that may cause cytotoxicity in the lens and lead to development of cataracts.

Intracellular functions and motile properties of bi-directional kinesin-5 Cin8 are regulated by neck linker docking

In this study, we analyzed intracellular functions and motile properties of neck-linker (NL) variants of the bi-directional S. cerevisiae kinesin-5 motor, Cin8. We also examined – by modeling – the configuration of H-bonds during NL docking. Decreasing the number of stabilizing H-bonds resulted in partially functional variants, as long as a conserved backbone H-bond at the N-latch position (proposed to stabilize the docked conformation of the NL) remained intact. Elimination of this conserved H-bond resulted in production of a non-functional Cin8 variant. Surprisingly, additional H-bond stabilization of the N-latch position, generated by replacement of the NL of Cin8 by sequences of the plus-end directed kinesin-5 Eg5, also produced a nonfunctional variant. In that variant, a single replacement of N-latch asparagine with glycine, as present in Cin8, eliminated the additional H-bond stabilization and rescued the functional defects. We conclude that exact N-latch stabilization during NL docking is critical for the function of bi-directional kinesin-5 Cin8.

The Mechanistic Effects and Clinical Applications of Various Derived Mesenchymal Stem Cells in Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is an acquired autoimmune disorder characterized by persistent thrombocytopenia resulting from increased platelet destruction and a loss of autoimmune tolerance. The pathogenesis of ITP is highly complex. Although ITP may be effectively controlled with currently available medications in some patients, a subset of cases remain refractory. The application of mesenchymal stem cells (MSCs) for human hematopoietic stem cell transplantation has increasingly demonstrated that MSCs modulate innate or adaptive immunity, thus resulting in a tolerant microenvironment. Functional defects and immunomodulatory disorders have been observed after the use of bone marrow mesenchymal stem cells (BM-MSCs) from patients with ITP. Here, we summarize the underlying mechanisms and clinical applications of various derived MSCs for ITP treatment, focusing on the main mechanisms underlying the functional defects and immune dysfunction of BM-MSCs from patients with ITP. Functional effects associated with the activation of the p53 pathway include decreased activity of the phosphatidylinositol 3 kinase/Akt pathway and activation of the TNFAIP3/NF-κB/SMAD7 pathway. Immune dysfunction appears to be associated with an impaired ability of BM-MSCs to induce various types of immune cells in ITP. At present, research focusing on MSCs in ITP remains in preliminary stages. The application of autologous or exogenous MSCs in the clinical treatment of ITP has been attempted in only a small case study and must be validated in larger-scale clinical trials.