Implementación del análisis en componentes principales con el software estadístico R

El Análisis en Componentes Principales (ACP) constituye la técnica base para el Análisis Multivariado de Datos. Su objetivo principal es reducir la cantidad de variables, manteniendo la máxima cantidad de información, presente en una tabla de datos de variables cuantitativas. En el presente artículo se expone un panorama general sobre la estructura que fundamenta un ACP y se implementa un caso concreto en el software estadístico R. Para ello es necesario un conocimiento básico de este software.

[1H,15N] N.M.R. Kinetic Studies of Reactions of cis- and trans-[PtCl2(15NH3)(c-C6H1115NH2)] with Guanosine 5'-Monophosphate

cis-[PtCl2(15NH3)(c-C6H11NH2)] is an active metabolite of the oral platinum(IV) anticancer drug cis,trans,cis-[PtCl2(CH3CO2)2(NH2)(c-C6H11NH2)]. Since it is likely that guanine bases on DNA are targets for this drug, we have analysed the kinetics of reaction of this platinum(II) metabolite with guanosine 5′-monophosphate (5′-GMP) at 310 K, pH 7, using [1H, 15N] n.m.r. methods. Reactions of the trans isomer are reported for comparison. The reactions proceed via aquated intermediates, and, for the cis isomer, the rates of aquation and substitution of H2O by 5′-GMP are 2-5 times faster trans to the amine ligand (c-C6H11NH2) compared to trans to NH3 for both the first and second steps. For the trans complex, the first aquation step is c. 3 times faster than for the cis complex, as expected from the higher trans influence of Cl¯, whereas the rate of the second aquation step (trans to N7 of 5′-GMP) is comparable to that trans to NH3. These findings have implications for the courses of reactions with DNA.

Letter from Wilfred T. Grenfell Esq., M.R.C.S.

An account of of the 1892(?) voyage from Yarmouth to St John's, Newfoundland, Canada.