RESUMEN
Thirty-six patients with type 2 diabetes mellitus (T2DM) were randomized 1:1:1 to receive a once-daily oral dose of placebo or 150 or 300 mg of the dual SGLT1/SGLT2 inhibitor LX4211 for 28 days. Relative to placebo, LX4211 enhanced urinary glucose excretion by inhibiting SGLT2-mediated renal glucose reabsorption; markedly and significantly improved multiple measures of glycemic control, including fasting plasma glucose, oral glucose tolerance, and HbA(1c); and significantly lowered serum triglycerides. LX4211 also mediated trends for lower weight, lower blood pressure, and higher glucagon-like peptide-1 levels. In a follow-up single-dose study in 12 patients with T2DM, LX4211 (300 mg) significantly increased glucagon-like peptide-1 and peptide YY levels relative to pretreatment values, probably by delaying SGLT1-mediated intestinal glucose absorption. In both studies, LX4211 was well tolerated without evidence of increased gastrointestinal side effects. These data support further study of LX4211-mediated dual SGLT1/SGLT2 inhibition as a novel mechanism of action in the treatment of T2DM.
Asunto(s)
Glucemia/efectos de los fármacos , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Glicósidos/uso terapéutico , Hipoglucemiantes/uso terapéutico , Transportador 1 de Sodio-Glucosa/antagonistas & inhibidores , Inhibidores del Cotransportador de Sodio-Glucosa 2 , Administración Oral , Adulto , Relación Dosis-Respuesta a Droga , Femenino , Péptido 1 Similar al Glucagón/sangre , Prueba de Tolerancia a la Glucosa , Hemoglobina Glucada/efectos de los fármacos , Hemoglobina Glucada/metabolismo , Glicósidos/administración & dosificación , Humanos , Hipoglucemiantes/efectos adversos , Absorción Intestinal , Masculino , Persona de Mediana Edad , Péptido YY/sangre , Triglicéridos/sangreRESUMEN
Defining the gene products that play an essential role in an organism's functional repertoire is vital to understanding the system level organization of living cells. We used a genetic footprinting technique for a genome-wide assessment of genes required for robust aerobic growth of Escherichia coli in rich media. We identified 620 genes as essential and 3,126 genes as dispensable for growth under these conditions. Functional context analysis of these data allows individual functional assignments to be refined. Evolutionary context analysis demonstrates a significant tendency of essential E. coli genes to be preserved throughout the bacterial kingdom. Projection of these data over metabolic subsystems reveals topologic modules with essential and evolutionarily preserved enzymes with reduced capacity for error tolerance.
Asunto(s)
Huella de ADN/métodos , Proteínas de Escherichia coli/genética , Escherichia coli/crecimiento & desarrollo , Genoma Bacteriano , Aerobiosis , Aminoácidos/biosíntesis , Medios de Cultivo , Elementos Transponibles de ADN , Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Evolución Molecular , Regulación Bacteriana de la Expresión Génica , Genes Esenciales , Mutagénesis Insercional , FilogeniaRESUMEN
Cyclic GMP-stimulated cyclic nucleotide phosphodiesterase (PDE2) is the second most abundant of this class of enzymes in platelets. PDE2 probably plays an important role in the regulation of elevated intracellular concentrations of cAMP and cGMP in platelets inhibited by prostacyclin and/or nitric oxide. The cAMP and cGMP PDEs have catalytic domains with 28-40% identity, but vary in their substrate specificity and affinity. As a first step toward the goal of identifying important amino acids in the substrate binding site pocket, we have employed the affinity analog 8-[(4-bromo-2, 3-dioxobutyl)thio]adenosine-3'5' cyclic monophosphate (8-BDB-TcAMP) to inactivate PDE2 and observe the pattern of protection by substrates and their products. Incubation of purified platelet PDE2 with 8-BDB-TcAMP (2-10 mM) resulted in a time-dependent, irreversible inactivation of the enzyme with a second-order rate constant of 0.013 min(-1) mM(-1). Both substrates, cAMP and cGMP, as well as the products of hydrolysis by PDE2, AMP and GMP, exhibited concentration-dependent protection against inhibition by 8-BDB-TcAMP, but no protection was noted with ADP or ATP, which are not hydrolyzed by the enzyme. This compound, 8-BDB-TcAMP, and similar affinity reagents should prove useful in delineating amino acids in the active site of PDE2.