Acute external otitis as debut of acute myeloid leukemia - A case and review of the literature.

Acute leukemia is a well known childhood cancer. The relation between leukemia and otological symptoms has long been established but is highly rare as a debut symptom of leukemia. External otitis is a common condition affecting many children, and most cases are successively treated with topical medicine. Here we present a child with acute external otitis later shown to be the debut symptom of acute myeloid leukemia, to our knowledge the first specific case described. We have reviewed the literature to find red flags for suspicion of severe disease in case of acute external otitis.

Botulinum Toxin Treatment of Objective Tinnitus Because of Essential Palatal Tremor: A Systematic Review.

INTRODUCTION: In contrast to subjective tinnitus, objective tinnitus can be heard by the examiner as well as by the patient. It can be triggered by, among many other etiologies, idiopathic muscular tremor in the soft palate, the essential palatal tremor (EPT). Many treatment modalities have been investigated, of which only Botulinum toxin (BT) injections have shown promising results. GOAL: The aim of this study was to evaluate the effect of BT treatment on objective tinnitus due to EPT by a systematic review of the literature. METHODS: In accordance with PRISMA guideline a systematic literature search in three databases was performed. RESULTS: Twenty-two studies fulfilled the inclusion criteria, mainly case reports and case series. A total of 51 BT treated patients diagnosed with EPT were identified in the literature. The studies were evaluated with focus on diagnostics, injection technique and BT dose, follow-up, effect on objective tinnitus, complications, and adverse effects. CONCLUSIONS: The included studies suffer from an extremely low evidence level with several sources of bias. When optimally injected, BT seems to be an effective treatment of objective tinnitus due to EPT, with few adverse effects and complications. We suggest BT injections as first choice in case of EPT and present a guideline regarding diagnostics, treatment, and follow-up.

Regulation of the Water Channel Aquaporin-2 via 14-3-3θ and -ζ.

The 14-3-3 family of proteins are multifunctional proteins that interact with many of their cellular targets in a phosphorylation-dependent manner. Here, we determined that 14-3-3 proteins interact with phosphorylated forms of the water channel aquaporin-2 (AQP2) and modulate its function. With the exception of σ, all 14-3-3 isoforms were abundantly expressed in mouse kidney and mouse kidney collecting duct cells (mpkCCD14). Long-term treatment of mpkCCD14 cells with the type 2 vasopressin receptor agonist dDAVP increased mRNA and protein levels of AQP2 alongside 14-3-3ß and -ζ, whereas levels of 14-3-3η and -θ were decreased. Co-immunoprecipitation (co-IP) studies in mpkCCD14 cells uncovered an AQP2/14-3-3 interaction that was modulated by acute dDAVP treatment. Additional co-IP studies in HEK293 cells determined that AQP2 interacts selectively with 14-3-3ζ and -θ. Use of phosphatase inhibitors in mpkCCD14 cells, co-IP with phosphorylation deficient forms of AQP2 expressed in HEK293 cells, or surface plasmon resonance studies determined that the AQP2/14-3-3 interaction was modulated by phosphorylation of AQP2 at various sites in its carboxyl terminus, with Ser-256 phosphorylation critical for the interactions. shRNA-mediated knockdown of 14-3-3ζ in mpkCCD14 cells resulted in increased AQP2 ubiquitylation, decreased AQP2 protein half-life, and reduced AQP2 levels. In contrast, knockdown of 14-3-3θ resulted in increased AQP2 half-life and increased AQP2 levels. In conclusion, this study demonstrates phosphorylation-dependent interactions of AQP2 with 14-3-3θ and -ζ. These interactions play divergent roles in modulating AQP2 trafficking, phosphorylation, ubiquitylation, and degradation.

Phosphorylation and ubiquitylation are opposing processes that regulate endocytosis of the water channel aquaporin-2.

The post-translational modifications (PTMs) phosphorylation and ubiquitylation regulate plasma membrane protein function. Here, we examine the interplay between phosphorylation and ubiquitylation of the membrane protein aquaporin-2 (AQP2) and demonstrate that phosphorylation can override the previously suggested dominant endocytic signal of K63-linked polyubiquitylation. In polarized epithelial cells, although S256 is an important phosphorylation site for AQP2 membrane localization, the rate of AQP2 endocytosis was reduced by prolonging phosphorylation specifically at S269. Despite their close proximity, AQP2 phosphorylation at S269 and ubiquitylation at K270 can occur in parallel, with increased S269 phosphorylation and decreased AQP2 endocytosis occurring when K270 polyubiquitylation levels are maximal. In vivo studies support this data, with maximal levels of AQP2 ubiquitylation occurring in parallel to maximal S269 phosphorylation and enhanced AQP2 plasma membrane localization. In conclusion, we demonstrate for the first time that although K63-linked polyubiquitylation marks AQP2 for endocytosis, site-specific phosphorylation can counteract polyubiquitylation to determine its final localization. Similar mechanisms might exist for other plasma membrane proteins.