RESUMEN
Proper control of cell cycle progression is critical for the constant self-renewal, differentiation, and homeostasis of the hematopoietic system. Cells of all types share the common cell cycle regulators. The different expression patterns of common regulators, in a broad sense, define cell-type or lineage specificity. However, there remains the possibility of hematopoietic cell cycle regulators tailored to the demands of the hematopoietic system. Here we describe a novel protein, HTm4, which serves as a hematopoietic cell cycle regulator. Our data indicate that HTm4 is expressed in hematopoietic tissues and is tightly regulated during the differentiation of hematopoietic stem cells. It binds to cyclin-dependent kinase-associated (CDK-associated) phosphatase-CDK2 (KAP-CDK2) complexes, and the three proteins demonstrate similar patterns of cellular expression in human lymphoid tissues. HTm4 stimulates the phosphatase activity of KAP, and its C-terminal region is required for binding to KAP-CDK2 complexes and the modulation of KAP activity. Overexpression of HTm4 can cause cell cycle arrest at the G(0)/G(1) phase. Thus, HTm4 is a novel hematopoietic modulator for the G(1)-S cell cycle transition.
Asunto(s)
Quinasas CDC2-CDC28 , Proteínas de Ciclo Celular , Ciclo Celular/fisiología , Hematopoyesis/fisiología , Proteínas de la Membrana/fisiología , Secuencia de Aminoácidos , Células Cultivadas , Quinasa 2 Dependiente de la Ciclina , Proteínas Inhibidoras de las Quinasas Dependientes de la Ciclina , Quinasas Ciclina-Dependientes/metabolismo , Fosfatasas de Especificidad Dual , Regulación de la Expresión Génica , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/fisiología , Humanos , Inmunohistoquímica , Proteínas de la Membrana/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Tirosina Fosfatasas/metabolismo , Transfección , Técnicas del Sistema de Dos HíbridosRESUMEN
Bothrops snake venoms contain metalloproteinases that contribute to the local effects seen after envenoming. In this work, a hemorrhagic metalloproteinase (BlaH1) was purified from the venom of the snake Bothrops lanceolatus by a combination of gel filtration, affinity (metal chelating) and hydrophobic interaction chromatographies. The hemorrhagin was homogeneous by SDS-PAGE and had a molecular mass of 28 kDa that was unaltered by treatment with beta-mercaptoethanol. BlaH1 gave a single band in immunoelectrophoresis and immunoblotting using commercial bothropic antivenom. BlaH1 had hemorrhagic, caseinolytic, fibrinogenolytic, collagenolytic and elastinolytic activities, but no phospholipase A(2) activity. The hemorrhagic and caseinolytic activities were inhibited by EDTA, indicating that they were metal ion-dependent. In contrast, aprotinin, benzamidine and PMSF did not affect these activities. The caseinolytic activity of BlaH1 had a pH optimum of 8.0 and was stable in solution at up to 40 degrees C; activity was completely lost at > or =70 degrees C. The hemorrhagic activity was neutralized by commercial bothropic antivenom. These properties suggest that this new hemorrhagin belongs to class P-I snake venom metalloproteinases.
Asunto(s)
Bothrops , Venenos de Crotálidos/aislamiento & purificación , Metaloendopeptidasas/aislamiento & purificación , Animales , Aprotinina/metabolismo , Benzamidinas/metabolismo , Caseínas/metabolismo , Cromatografía de Afinidad , Cromatografía en Gel , Colagenasas/metabolismo , Venenos de Crotálidos/química , Venenos de Crotálidos/metabolismo , Ácido Edético/metabolismo , Electroforesis en Gel de Poliacrilamida , Endopeptidasas/metabolismo , Esterasas/metabolismo , Fibrinógeno/metabolismo , Immunoblotting , Masculino , Metaloendopeptidasas/química , Metaloendopeptidasas/metabolismo , Fosfolipasas A/metabolismo , Ratas , Ratas Wistar , TemperaturaRESUMEN
We report microwave-assisted synthetic routes, the pharmacokinetic profile along with results from ulcerogenicity and mutagenicity studies of atenolol aspirinate, and an already described derivative, in which acetyl salicylic acid (aspirin) was connected to atenolol by an ester linkage. Atenolol aspirinate was stable towards aqueous hydrolysis but rapidly hydrolyzed in plasma (t(1/2) = 7.6 min). The results showed that the rapid and complete hydrolysis generates atenolol salicylate, which assumes a conformation stabilized by two intramolecular H-bonds, avoiding its further hydrolysis to salicylic acid and atenolol.
Asunto(s)
Antihipertensivos/farmacocinética , Aspirina/química , Atenolol/farmacocinética , Animales , Antihipertensivos/química , Antihipertensivos/metabolismo , Área Bajo la Curva , Atenolol/química , Atenolol/metabolismo , Mucosa Gástrica/efectos de los fármacos , Semivida , Humanos , Microondas , Modelos Moleculares , Pruebas de Mutagenicidad , Profármacos/química , Profármacos/metabolismo , Profármacos/farmacocinéticaRESUMEN
We assessed the effect of local anesthetics (LA) from different families such as esters (benzocaine), linear aminoamides (lidocaine) and cyclic aminoamides (bupivacaine) on the platelet aggregation induced by ADP. Liposomal formulations of the three LA, prepared with egg phosphatidylcholine:cholesterol alpha-tocopherol, were also tested. The three LA were able to inhibit platelet aggregation induced by ADP, in the following order: bupivacaine > lidocaine > benzocaine. After encapsulation into liposomes the inhibitory effect increased for all anesthetics studied, showing that aggregation tests could be used to assess the toxicity of new drug formulations.