Coexistence of tumor-induced osteomalacia and primary hyperparathyroidism

ObjectiveTo present an unusual case of coexisting tumor-induced osteomalacia (TIO) and primary hyperparathyroidism (PHPT).MethodsWe report the clinical features, imaging studies, and the results of laboratory investigations before and after surgical resection of both a soft-tissue tumor and a parathyroid adenoma.ResultsA 44-year-old woman was referred to the endocrinology department with a diagnosis of PHPT accompanied by unusually severe hypophosphatemia, despite having received treatment with cinacalcet. Debilitating muscle weakness and bone pain, severe phosphaturia and hypophosphatemia, inappropriately normal calcitriol, and elevated fibroblast growth factor-23 and intact parathyroid hormone levels raised the suspicion of coexisting TIO and PHPT. Imaging studies were negative, but histologic characteristics of a palpable subcutaneous mass from the patient’s thigh revealed a phosphaturic mesenchymal tumor. Complete remission after surgical removal of both the soft-tissue tumor and the parathyroid adenoma confirmed the diagnosis.ConclusionThe coexistence of TIO and PHPT has not been described before and can cause life-threatening hypophosphatemia. Diagnosis and localization of the tumor is of paramount importance since surgery is the treatment of choice for both TIO and PHPT. (Endocr Pract. 2011;17:e144-e148)     

A histone-like protein of mycobacteria possesses ferritin superfamily protein-like activity and protects against DNA damage by Fenton reaction

Iron is an essential metal for living organisms but its level must be strictly controlled in cells, because ferrous ion induces toxicity by generating highly active reactive oxygen, hydroxyl radicals, through the Fenton reaction. In addition, ferric ion shows low solubility under physiological conditions. To overcome these obstacles living organisms possess Ferritin superfamily proteins that are distributed in all three domains of life: bacteria, archaea, and eukaryotes. These proteins minimize hydroxyl radical formation by ferroxidase activity that converts Fe(2+) into Fe(3+) and sequesters iron by storing it as a mineral inside a protein cage. In this study, we discovered that mycobacterial DNA-binding protein 1 (MDP1), a histone-like protein, has similar activity to ferritin superfamily proteins. MDP1 prevented the Fenton reaction and protects DNA by the ferroxidase activity. The K(m) values of the ferroxidase activity by MDP1 of Mycobacterium bovis bacillus Calmette-Guérin (BCG-3007c), Mycobacterium tuberculosis (Rv2986c), and Mycobacterium leprae (ML1683; ML-LBP) were 0.292, 0.252, and 0.129 mM, respectively. Furthermore, one MDP1 molecule directly captured 81.4±19.1 iron atoms, suggesting the role of this protein in iron storage. This study describes for the first time a ferroxidase-iron storage protein outside of the ferritin superfamily proteins and the protective role of this bacterial protein from DNA damage.     

ARMC4 Mutations Cause Primary Ciliary Dyskinesia with Randomization of Left/Right Body Asymmetry

The motive forces for ciliary movement are generated by large multiprotein complexes referred to as outer dynein arms (ODAs), which are preassembled in the cytoplasm prior to transport to the ciliary axonemal compartment. In humans, defects in structural components, docking complexes, or cytoplasmic assembly factors can cause primary ciliary dyskinesia (PCD), a disorder characterized by chronic airway disease and defects in laterality. By using combined high resolution copy-number variant and mutation analysis, we identified ARMC4 mutations in twelve PCD individuals whose cells showed reduced numbers of ODAs and severely impaired ciliary beating. Transient suppression in zebrafish and analysis of an ENU mouse mutant confirmed in both model organisms that ARMC4 is critical for left-right patterning. We demonstrate that ARMC4 is an axonemal protein that is necessary for proper targeting and anchoring of ODAs.     

Keto-fluorothiopyranosyl nucleosides: a convenient synthesis of 2- and 4-keto-3-fluoro-5-thioxylopyranosyl thymine analogs

A novel series of fluorinated keto-β-d-5-thioxylopyranonucleosides bearing thymine as the heterocyclic base have been designed and synthesized. Deprotection of 3-deoxy-3-fluoro-5-S-acetyl-5-thio-d-xylofuranose (1) and selective acetalation gave the desired isopropylidene 5-thioxylopyranose precursor 3. Acetylation and isopropylidene removal followed by benzoylation led to 3-deoxy-3-fluoro-1,2-di-Ο-benzoyl-4-O-acetyl-5′-thio-d-xylopyranose (6). This was condensed with silylated thymine and selectively deacetylated to afford 1-(2′-Ο-benzoyl-3′-deoxy-3′-fluoro-5′-thio-β-d-xylopyranosyl)thymine (8). Oxidation of the free hydroxyl group in the 4′-position of the sugar led to the formation of the target 4′-keto compound together with the concomitant displacement of the benzoyl group by an acetyl affording, 1-(2′-O-acetyl-3′-deoxy-3′-fluoro-β-d-xylopyranosyl-4′-ulose)thymine (9). Benzoylation of 3 and removal of the isopropylidene group followed by acetylation, furnished 3-deoxy-3-fluoro-1,2-di-Ο-acetyl-4-O-benzoyl-5′-thio-d-xylopyranose (12). Condensation of thiosugar 12 with silylated thymine followed by selective deacetylation led to the 1-(4′-Ο-benzoyl-3′-fluoro-5′-thio-β-d-xylopyranosyl)thymine (14). Oxidation of the free hydroxyl group in the 2′-position and concomitant displacement of the benzoyl group by an acetyl gave target 1-(4′-O-acetyl-3′-deoxy-3′-fluoro-β-d-xylopyranosyl-2′-ulose)thymine (15).     

Deregulation of the p57-E2F1-p53 axis results in nonobstructive hydrocephalus and cerebellar malformation in mice

The cyclin-dependent kinase inhibitor (CKI) p57(Kip2) plays a pivotal role in cell cycle arrest during development, in particular, in the regulation of the entry of proliferating progenitors into quiescence. The gene encoding p57 undergoes genomic imprinting, and impairment of the regulation of p57 expression results in various developmental anomalies in humans and mice. We now show that p57 is expressed predominantly in the subcommissural organ and cerebellar interneurons in the mouse brain and that mice with brain-specific deletion of the p57 gene (Kip2) manifest prominent nonobstructive hydrocephalus as well as cerebellar malformation associated with the loss of Pax2-positive interneuron precursors and their descendants, including Golgi cells and γ-aminobutyric acid-containing neurons of the deep cerebellar nuclei. These abnormalities were found to be attributable to massive apoptosis of precursor cells in the developing brain. The morphological defects of the p57-deficient mice were corrected by knock-in of the gene for the related CKI p27(Kip1) at the Kip2 locus. The abnormalities were also prevented by additional genetic ablation of p53 or E2F1. Our results thus implicate p57 in cell cycle arrest in the subcommissural organ and Pax2-positive interneuron precursors, with the lack of p57 resulting in induction of p53-dependent apoptosis due to hyperactivation of E2F1.     

α-Tocopheryl phosphate: uptake, hydrolysis, and antioxidant action in cultured cells and mouse

α-Tocopheryl phosphate (α-TP), a water-soluble analogue of α-tocopherol, is found in humans, animals, and plants. α-TP is resistant to both acid and alkaline hydrolysis and may exert its own function in this form in vivo. In this study, the uptake, hydrolysis, and antioxidant action of α-TP were measured using α-TP with a deuterated methyl group, CD(3), at position 5 of the chroman ring (α-TP(CD3)). The hydrolysis of α-TP(CD3) was followed by measuring α-tocopherol containing the CD(3) group, α-T(CD3), in comparison to unlabeled α-tocopherol, α-T(CH3). α-TP(CD3) was incubated with cultured cells, and the intracellular α-T(CD3) formed was measured with HPLC-ECD and GC-MS. α-TP(CD3) was also administered to mice for 4 weeks by mixing in the diet, and α-T(CD3) was measured in plasma, liver, brain, heart, and testis to compare with endogenous unlabeled α-T(CH3). It was found that α-TP(CD3) was taken in and hydrolyzed readily to α-T(CD3) in cultured cells and in mice. The hydrolysis of α-TP(CD3) in cell culture medium was not observed. α-TP protected primary cortical neuronal cells from glutamate-induced cytotoxicity, and α-TP given to mice reduced the levels of lipid peroxidation products in plasma and liver. These results suggest that α-TP is readily hydrolyzed in vivo to α-T, which acts as an antioxidant, and that α-TP may be used as a water-soluble α-T precursor in intravenous fluids, in eye drops, or as a dietary supplement.     

Lipid phenotype of two distinct subpopulations of Mycobacterium bovis Bacillus Calmette-Guerin Tokyo 172 substrain

Bacillus Calmette-Guérin (BCG) Tokyo 172 is a predominant World Health Organization Reference Reagent for the BCG vaccine. Recently, the BCG Tokyo 172 substrain was reported to consist of two subpopulations with different colony morphologies, smooth and rough. Smooth colonies had a characteristic 22-bp deletion in Rv3405c of the region of difference (RD) 16 (type I), and rough colonies were complete in this region (type II). We hypothesized that the morphological difference is related to lipid phenotype and affects their antigenicity. We determined the lipid compositions and biosynthesis of types I and II. Scanning electron microscopy showed that type I was 1.5 times longer than type II. Phenolic glycolipid (PGL) and phthiocerol dimycocerosate (PDIM) were found only in type I. Although it has been reported that the RD16 is involved in the expression of PGL, type II did not possess PGL/PDIM. We examined the ppsA-E gene responsible for PGL/PDIM biosynthesis and found that the existence of PGL/PDIM in types I and II is caused by a ppsA gene mutation not regulated by the RD16. PGL suppressed the host recognition of total lipids via Toll-like receptor 2, and this suggests that PGL is antigenic and involved in host responses, acting as a cell wall component. This is the first report to show the difference between lipid phenotypes of types I and II. It is important to clarify the heterogeneity of BCG vaccine substrains to discuss and evaluate the quality, safety, and efficacy of the BCG vaccine.     

Dysregulation of TIM-3-galectin-9 pathway in the cystic fibrosis airways

The T-cell Ig and mucin domain-containing molecules (TIMs) have emerged as promising therapeutic targets to correct abnormal immune function in several autoimmune and chronic inflammatory conditions. It has been reported that proinflammatory cytokine dysregulation and neutrophil-dominated inflammation are the main causes of morbidity in cystic fibrosis (CF). However, the role of TIM receptors in CF has not been investigated. In this study, we demonstrated that TIM-3 is constitutively overexpressed in the human CF airway, suggesting a link between CF transmembrane conductance regulator (CFTR) function and TIM-3 expression. Blockade of CFTR function with the CFTR inhibitor-172 induced an upregulation of TIM-3 and its ligand galectin-9 in normal bronchial epithelial cells. We also established that TIM-3 serves as a functional receptor in bronchial epithelial cells, and physiologically relevant concentrations of galectin-9 induced TIM-3 phosphorylation, resulting in increased IL-8 production. In addition, we have demonstrated that both TIM-3 and galectin-9 undergo rapid proteolytic degradation in the CF lung, primarily because of neutrophil elastase and proteinase-3 activity. Our results suggest a novel intrinsic defect that may contribute to the neutrophil-dominated immune response in the CF airways.