RESUMEN
OBJECTIVE: Mercaptopurine (MP) and pro-drug azathioprine are 'first-line' oral therapies for maintaining remission in IBD. It is believed that their pharmacodynamic action is due to a slow cumulative decrease in activated lymphocytes homing to inflamed gut. We examined the role of host metabolism, lymphocytes and microbiome for the amelioration of colitis by the related thioguanine (TG). DESIGN: C57Bl/6 mice with or without specific genes altered to elucidate mechanisms responsible for TG's actions were treated daily with oral or intrarectal TG, MP or water. Disease activity was scored daily. At sacrifice, colonic histology, cytokine message, caecal luminal and mucosal microbiomes were analysed. RESULTS: Oral and intrarectal TG but not MP rapidly ameliorated spontaneous chronic colitis in Winnie mice (point mutation in Muc2 secretory mucin). TG ameliorated dextran sodium sulfate-induced chronic colitis in wild-type (WT) mice and in mice lacking T and B lymphocytes. Remarkably, colitis improved without immunosuppressive effects in the absence of host hypoxanthine (guanine) phosphoribosyltransferase (Hprt)-mediated conversion of TG to active drug, the thioguanine nucleotides (TGN). Colonic bacteria converted TG and less so MP to TGN, consistent with intestinal bacterial conversion of TG to so reduce inflammation in the mice lacking host Hprt. TG rapidly induced autophagic flux in epithelial, macrophage and WT but not Hprt-/- fibroblast cell lines and augmented epithelial intracellular bacterial killing. CONCLUSIONS: Treatment by TG is not necessarily dependent on the adaptive immune system. TG is a more efficacious treatment than MP in Winnie spontaneous colitis. Rapid local bacterial conversion of TG correlated with decreased intestinal inflammation and immune activation.
Asunto(s)
Colitis/tratamiento farmacológico , Microbioma Gastrointestinal/fisiología , Inmunosupresores/uso terapéutico , Mucosa Intestinal/microbiología , Mercaptopurina/metabolismo , Mercaptopurina/uso terapéutico , Tioguanina/metabolismo , Tioguanina/uso terapéutico , Administración Oral , Administración Rectal , Animales , Autofagia/efectos de los fármacos , Bacteroides thetaiotaomicron/metabolismo , Células Cultivadas , Colitis/inducido químicamente , Colitis/genética , Colitis/patología , Colon/microbiología , Citocinas/genética , Sulfato de Dextran , Enterococcus faecalis/metabolismo , Células Epiteliales , Escherichia coli/metabolismo , Femenino , Fibroblastos , Interacciones Huésped-Patógeno , Hipoxantina Fosforribosiltransferasa/genética , Inmunosupresores/administración & dosificación , Inmunosupresores/metabolismo , Macrófagos , Masculino , Mercaptopurina/farmacología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mucina 2/genética , ARN Mensajero/metabolismo , Linfocitos T/inmunología , Tioguanina/farmacologíaRESUMEN
BACKGROUND: Plasma concentrations of HDL cholesterol (HDL-C) and its major protein component apolipoprotein (Apo) A-I are strongly inversely associated with cardiovascular risk, leading to the concept that therapy to increase HDL-C and ApoA-I concentrations would be antiatherosclerotic and protective against cardiovascular events. The recent failure of the drug torcetrapib, a cholesteryl ester transfer protein inhibitor that substantially increased HDL-C concentrations, has brought focus on the issues of HDL heterogeneity and function as distinct from HDL-C concentrations. CONTENT: This review addresses the current state of knowledge regarding assays of HDL heterogeneity and function and their relationship to cardiovascular disease. HDL is highly heterogeneous, with subfractions that can be identified on the basis of density, size, charge, and protein composition, and the concept that certain subfractions of HDL may be better predictors of cardiovascular risk is attractive. In addition, HDL has been shown to have a variety of functions that may contribute to its cardiovascular protective effects, including promotion of macrophage cholesterol efflux and reverse cholesterol transport and antiinflammatory and nitric oxide-promoting effects. SUMMARY: Robust laboratory assays of HDL subfractions and functions and validation of the usefulness of these assays for predicting cardiovascular risk and assessing response to therapeutic interventions are critically important and of great interest to cardiovascular clinicians and investigators and clinical chemists.
Asunto(s)
Enfermedades Cardiovasculares/sangre , Lipoproteínas HDL/sangre , Apolipoproteína A-I/sangre , Apolipoproteínas/sangre , Biomarcadores/sangre , Enfermedades Cardiovasculares/epidemiología , HDL-Colesterol/sangre , Humanos , Valor Predictivo de las Pruebas , Factores de RiesgoRESUMEN
OBJECTIVES: A multicenter, double-blind study was conducted in 268 patients to compare the safety and efficacy of 15, 30, and 60 mg of lansoprazole and placebo in the treatment of gastric ulcer. METHODS: The study included an 8-wk treatment period to assess healing and a 6-month posttreatment period to evaluate ulcer recurrence. Endoscopies were performed, GI symptoms and antacid use were assessed, and safety evaluations were conducted, including serum gastrin and biopsies of the lesions and the greater curvature of the stomach. RESULTS: At week 4, healing rates were significantly higher with lansoprazole 15 and 30 mg (64.6 and 58.1%, respectively) compared with placebo (37.5%). By week 8, healing rates were 76.7% with placebo, 92.2% with 15 mg of lansoprazole, 96.8% with 30 mg, and 93.2% with 60 mg of lansoprazole (p < 0.05). The drug was well tolerated, with no significant differences from placebo in the incidence of adverse events. Fasting serum gastrin increased in all lansoprazole groups, reaching a plateau by week 2 and returning to baseline levels by month 1 posttreatment. No significant increase in Grimelius-positive cells or inflammation was evident. All but two patients had normal gastric morphology evaluated by Solcia classification. CONCLUSIONS: Lansoprazole, 15, 30, and 60 mg, administered once daily before eating, healed gastric ulcers to an approximately equal degree, and all were significantly better than placebo.
Asunto(s)
Antiulcerosos/administración & dosificación , Omeprazol/análogos & derivados , Inhibidores de la Bomba de Protones , Úlcera Gástrica/tratamiento farmacológico , 2-Piridinilmetilsulfinilbencimidazoles , Antiulcerosos/efectos adversos , Biopsia , Método Doble Ciego , Esquema de Medicación , Femenino , Estudios de Seguimiento , Mucosa Gástrica/patología , Gastroscopía , Humanos , Lansoprazol , Masculino , Persona de Mediana Edad , Omeprazol/administración & dosificación , Omeprazol/efectos adversos , Recurrencia , Úlcera Gástrica/diagnóstico , Factores de Tiempo , Cicatrización de HeridasRESUMEN
We have investigated the effects of an inhibitor of ceramide biosynthesis on the glycosylphosphatidylinositol (GPI)-anchoring and intracellular transport of the yeast Gas1 protein. No effect on anchor attachment was demonstrable, but a selective delay in transport from the endoplasmic reticulum to the Golgi complex was observed. The compound also blocked remodeling of GPI-anchors from their base-sensitive to base-resistant forms. A recessive mutation was found that caused resistance to the drug, restored transport of Gas1p, but did not restore ceramide biosynthesis in the presence of the inhibitor. Our results suggest that intracellular transport of GPI-anchored proteins is stimulated by new ceramide synthesis. The role of ceramide may be direct or may be through its use in the remodeling of GPI-anchored proteins other than Gas1p. The need for ceramide can be overcome in the mutant strain.
Asunto(s)
Ceramidas/metabolismo , Proteínas Fúngicas/metabolismo , Glicosilfosfatidilinositoles/química , Aparato de Golgi/metabolismo , Glicoproteínas de Membrana/metabolismo , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolismo , Ceramidas/fisiología , Retículo Endoplásmico/metabolismoRESUMEN
We have investigated the effects of an inhibitor of ceramide biosynthesis on the glycosylphosphatidylinositol (GPI)-anchoring and intracellular transport of the yeast Gas 1 protein. No effect on anchor attachment was demonstrable, but a selective delay in transport from the endoplasmic reticulum to the Golgi complex was observed. The compound also blocked remodeling of GPI-anchors from their base-sensitive to base-resistant forms. A recessive mutation was found that caused resistance to the drug, restored transport of Gas 1p, but did not restore ceramide biosynthesis in the presence of the inhibitor. Our results suggest that intracellular transport of GPI-anchored proteins is stimulated by new ceramide synthesis. The role of ceramide may be direct or may be through its use in the remodeling of GPI-anchored proteins other than Gas 1p. The need for ceramide can be overcome in the mutant strain
Asunto(s)
Ceramidas/biosíntesis , Fosfatidilinositoles/metabolismo , Glucolípidos/metabolismo , Levaduras , Secuencia de Aminoácidos , Retículo Endoplásmico , Saccharomyces cerevisiaeRESUMEN
Cyclosporin A (Sandimmun) achieves immunosuppressive activity by complex formation with cyclophilin and subsequent binding of the binary complex to and inhibiting protein phosphatase 2B (calcineurin). Complexes of nonimmunosuppressive cyclophilin binding cyclosporin analogues do not inhibit protein phosphatase 2B, suggesting a crucial role for this enzyme in T cell activation. Binding of cyclosporin A to cyclophilins A, B, and C, respectively, results in complexes of significantly different inhibitory potency. The cyclosporin molecule thus has two functional domains, one mediating cyclophilin binding and a second one endowing affinity of the complex to calcineurin, thereby inhibiting its enzyme activity. Structure-activity studies and x-ray crystallography of cyclosporin-cyclophilin complexes indicate a crucial role of leucine side chains in positions 4 and 6 of the cyclosporin macrocycle for the calcineurin interaction.
Asunto(s)
Ciclosporinas/farmacología , Secuencia de Aminoácidos , Animales , Ciclosporinas/química , Humanos , Datos de Secuencia Molecular , Relación Estructura-ActividadRESUMEN
A synthetic gene coding for human somatomedin C (SMC) was inserted into an Escherichia coli plasmid vector that contains the bacteriophage lambda pL promoter. Intracellular accumulation of the gene product after induction of the promoter was found to be low. A 200-fold greater yield was obtained with a similar plasmid containing two translationally fused copies of the SMC gene. A series of such tandem genes truncated at their 3' ends were generated with nuclease Bal 31. These gave intermediate expression levels that correlated with the expected sizes of their gene products. Comparison of RNAs extracted from cells containing either the monomer or tandem SMC gene constructions showed that there was no significant difference in expression at the transcriptional level. Pulse-chase experiments demonstrated that the tandem SMC protein was far more stable than the monomer SMC product.