Glycosphingolipid receptors for anti-Gd and anti-p cold agglutinins

Anti-Gd and anti-p cold agglutinins exhibit similar serological properties: neuraminidase treatment of erythrocytes greatly reduces their agglutinability by these antibodies and protease treatment enhances their agglutination. We reported previously that an anti-p cold agglutinin was inhibited by sialosyllactoneotetraosylceramide, NeuAc(α2–3)Gal(β1–4)GlcNAc(β1–3)Gal(β1–4)Glc-Cer, the most abundant ganglioside of human eryhrocytes. We now report that two less abundant gangliosides are more potent inhibitors of this antibody, and of the anti-Gd antibodies, than sialosyllactoneotetraosyl-ceramide. These two gangliosides have the same carbohydrate chain, NeuAc(α2–3)Gal(β1–4)GlcNAc(β1–3)Gal(β1–4) GlcNAc(β1–3)Gal(β1–4)Glc (SNH), but they differ in their ceramide moiety. The principal fatty acid of SNH-1 is C_16:0, whereas SNH-2 contains a predominance of C_22:0, C_24:0 and C_24:1. No inhibition was produced by the ganglioside, NeuAc(α2–6)Gal(β1–4)GlcNAc(β1–3)Gal(β1–4)Glc-Cer.Another monoclonal cold agglutinin, Sa, which shares some serological properties with anti-Gd cold agglutinins, was not inhibited by any of these gangliosides.     

Exon scanning for mutation of the NF2 gene in schwannomas

Family studies and tumor analyses have combined to indicatethat neurofibromatosls 2 (NF2), a disorder characterized bymultiple benign tumors of the nervous system, and sporadic non-Inheritedforms of the same tumor types are both caused by inactlvationof a tumor suppressor gene located in 22q12. Recently, the geneencoding merlin, a novel member of a family of cytoskeleton-associatedproteins, was Identified as the NF2 tumor suppressor. To facilitatethe search for merlin mutations, we have defined the exon-intronboundaries for all 17 NF2 exons, including one subject to alternativesplicing. We have developed polymerase chain reaction assaysto amplify each exon from genomlc DNA, and used these assaysto perform single-strand conformation polymorphism analysisof DNA from 30 sporadic and eight NF2-derlved schwannomas, thehallmark tumor type In this disorder. Of a maximum of 60 allelesscanned, 32 showed mutations affecting expression of the merlinprotein. Thirty of these mutations are predicted to lead toa truncated protein due to frameshift, creation of a stop codon,or interference with normal splicing, while two are missensemutations. Thus, Inactivation of merlin is a common featureunderlying both Inherited and sporadic forms of schwannoma.     

Sublethal oxidative stress inhibits tumor cell adhesion and enhances experimental metastasis of murine mammary carcinoma

We have postulated that murine mammary tumor progression is fueled, in part, by tumor-associated macrophages that deliver sub-lethal oxidative stress to tumor cells. In the present study, we determined whether oxidative stress would affect murine mammary tumor cell attachment to laminin and fibronectin, critical functions in the metastatic process. Sublethal oxidative stress generated by exposure of cells to hydrogen peroxide (H₂O₂, 1–1000 M/L) inhibited tumor cell attachment to immobilized laminin or fibronectin. This oxidant effect was blocked in the presence of catalase which removes H₂O₂. The inhibitory effect on attachment was rapid, with significant inhibition occurring at 5 min; total inhibition was achieved at 60 min with 1 mM H₂O₂. The oxidative stress effect was partially reversible at 20 h post-treatment and occurred at concentrations of H₂O₂ that do not adversely affect cell viability or growth. Pretreatment of tumor cells with H₂O₂ or hypoxanthanine and xanthine oxidase (to generate superoxide radical and H₂O₂) prior to intravenous injection, enhanced experimental lung tumor colony formation. The enhancement of experimental metastatic potential with enzyme-generated oxidative stress was completely reversed by catalase; the H₂O₂-mediated enhancement was only partially reversed with catalase. Thus, treatments that inhibit tumor cell attachment to extracellular matrix proteins in vitro enhance experimental metastasis in vivo.     

ERYTHROCYTE GLYCOSPHINGOLIPIDS OF FOUR SIBLINGS WITH THE RARE BLOOD GROUP p PHENOTYPE AND THEIR PARENTS

Erythrocytes that exhibit the rare blood group p phenotype lack the P antigen (globotetraosylceramide) and the P^k antigen (globotriaosylceramide). This phenotype is inherited as an autosomal recessive condition and the red cells of heterozygous individuals, parents and children of p persons, are serologically normal but no chemical analyses of their red cells have been reported. We have studied an unusual family in which all five children exhibit the p phenotype. In addition to the abnormalities described previously, the erythrocytes of four siblings had twice the normal concentration of lactotriaoslyceramide and lactoneotetraosylceramide. These cells also contained 3-5 times as much sialosyllactoneotetraosylceramide and up to a two-fold increase in G_M3 ganglioside. The glycolipids of the parents' erythrocytes were normal. Electrophoretic analysis of the glycoproteins of the proposita's erythrocytes revealed no abnormalities, but her erythrocyte membranes contained approximately 35% less galactosamine than normal red cells. This abnormality resulted from a marked decrease in galactosamine that was soluble in chloroformmethanol. The lipid-extracted residue, which contained the glycoproteins, had a normal galactosamine content.     

Effect of ciclesonide and fluticasone on hypothalamic-pituitary-adrenal axis function in adults with mild-to-moderate persistent asthma.

BACKGROUND: Despite their proven efficacy in the treatment and prevention of asthma exacerbations, current inhaled corticosteroids carry safety concerns, especially adrenal suppression. Ciclesonide (hydrofluoroalkane propellant) is a novel inhaled corticosteroid with few, if any, clinical adverse events. OBJECTIVE: To evaluate the potential effects of ciclesonide therapy on the dynamic cortisol response to sequential low- and high-dose cosyntropin stimulation in adults with mild-to-moderate persistent asthma. METHODS: This was a double-blind, randomized, placebo-controlled, 12-week study in adults with mild-to-moderate asthma. One hundred sixty-four patients were randomized and treated; 148 patients completed the study. Fluticasone propionate (chlorofluorocarbon propellant) was used as an active comparator. The doses administered were 320 microg of ciclesonide once daily, 320 microg of ciclesonide twice daily, and 440 microg of fluticasone propionate twice daily, all doses ex-actuator. RESULTS: For both ciclesonide groups, changes in mean low- and high-dose peak serum cortisol levels and in 24-hour urinary free cortisol levels corrected for creatinine were small vs baseline and comparable with placebo. For the fluticasone propionate group, significant reductions vs placebo in serum cortisol levels in response to high-dose cosyntropin stimulation and in 24-hour urinary free cortisol levels were observed. Oral candidiasis rates were 2.5% for 320-microg/d ciclesonide, 2.4% for 640-microg/d ciclesonide, and 22.0% for 880-microg/d fluticasone propionate. CONCLUSIONS: These findings confirm the safety of ciclesonide therapy, demonstrating that at doses up to 640 microg/d, the drug does not affect sensitive markers of adrenal function.     

Methylated trivalent arsenicals as candidate ultimate genotoxic forms of arsenic: induction of chromosomal mutations but not gene mutations

Arsenic is a prevalent human carcinogen whose mutagenicity has not been characterized fully. Exposure to either form of inorganic arsenic, As(III) or As(V), can result in the formation of at least four organic metabolites: monomethylarsonic acid, monomethylarsonous acid (MMA(III)), dimethylarsinic acid, and dimethylarsinous acid (DMA(III)). The methylated trivalent species, as well as some of the other species, have not been evaluated previously for the induction of chromosome aberrations, sister chromatid exchanges (SCE), or toxicity in cultured human peripheral blood lymphocytes; for mutagenicity in L5178Y/Tk(+/-) mouse lymphoma cells or in the Salmonella reversion assay; or for prophage-induction in Escherichia coli. Here we evaluated the arsenicals in these assays and found that MMA(III) and DMA(III) were the most potent clastogens of the six arsenicals in human lymphocytes and the most potent mutagens of the six arsenicals at the Tk(+/-) locus in mouse lymphoma cells. The dimethylated arsenicals were also spindle poisons, suggesting that they may be ultimate forms of arsenic that induce aneuploidy. Although the arsenicals were potent clastogens, none were potent SCE inducers, similar to clastogens that act via reactive oxygen species. None of the six arsenicals were gene mutagens in Salmonella TA98, TA100, or TA104; and neither MMA(III) nor DMA(III) induced prophage. Our results show that both methylated As(V) compounds were less cytotoxic and genotoxic than As(V), whereas both methylated As(III) compounds were more cytotoxic and genotoxic than As(III). Our data support the view that MMA(III) and DMA(III) are candidate ultimate genotoxic forms of arsenic and that they are clastogens and not gene mutagens. We suggest that the clastogenicity of the other arsenicals is due to their metabolism by cells to MMA(III) or DMA(III).     

P/CAF mediates PAX3–FOXO1‐dependent oncogenesis in alveolar rhabdomyosarcoma

Alveolar rhabdomyosarcoma (ARMS) is an aggressive paediatric cancer of skeletal muscle with poor prognosis. A PAX3–FOXO1 fusion protein acts as a driver of malignancy in ARMS by disrupting tightly coupled but mutually exclusive pathways of proliferation and differentiation. While PAX3–FOXO1 is an attractive therapeutic target, no current treatments are designed to block its oncogenic activity. The present work shows that the histone acetyltransferase P/CAF (KAT2B) is overexpressed in primary tumours from ARMS patients. Interestingly, in fusion‐positive ARMS cell lines, P/CAF acetylates and stabilizes PAX3–FOXO1 rather than MyoD, a master regulator of muscle differentiation. Silencing P/CAF, or pharmacological inhibition of its acetyltransferase activity, down‐regulates PAX3–FOXO1 levels concomitant with reduced proliferation and tumour burden in xenograft mouse models. Our studies identify a P/CAF–PAX3–FOXO1 signalling node that promotes oncogenesis and may contribute to MyoD dysfunction in ARMS. This work exemplifies the therapeutic potential of targeting chromatin‐modifying enzymes to inhibit fusion oncoproteins that are a frequent event in sarcomas. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.