Article
Is the cardioprotector effect of estrogens useful in the menopause? [¿Es útil el efecto cardioprotector de los estrógenos en la menopausia?]
Fecha
2002Autor
Goguitchaichvili, A.
Alva Valdivia, L.M.
Elguera, J.R.
Fucugauchi, J.U.
Cervantes, M.A.
Morales, J.
Institución
Resumen
We have sampled a sequence of 45 late Miocene consecutive lava flows in the Tepic area (Nayarit State, Mexico). The age of the volcanic units lies between 8 and 9 million years (Ma) according to available radiometric data. All samples were step-wise demagnetized, partly with alternating field (AF), partly thermally with very similar results. Most of the rocks exhibited well-defined one component remanent magnetisation with high unblocking temperatures (mostly above 525 °C) and high median destructive fields (MDF) (40-50 mT). Rock-magnetic experiments combined with microscopy show that, in most cases, the main magnetic mineral is Ti-poor titanomagnetic associated with exsoluted ilmenite. Continuous susceptibility measurements with temperature and hysteresis experiments yield in most cases nearly reversible curves with Curie points close to that of magnetite and pseudo-single-domain characteristics. Characteristic remanent magnetisations (ChRM) isolated after the first steps of demagnetisation are all normal polarity. According to the dispersion of virtual geomagnetic pole (VGP) directions, paleosecular variation was abnormally lower than the one observed in general during Miocene. Considering our paleomagnetic results together with available radiometric data, it seems that the volcanic units have been emplaced during a very short time span of about 0.08 million years. The mean paleomagnetic directions obtained from this study do not differ significantly from that expected for the middle Miocene. Thirty-one samples from eight individual flows yielded acceptable paleointensity estimates. The site mean paleointensities range from 27.8 0.9 to 42.0 7.9 ?T. The virtual dipole moments (VDM) range from 5.9 to 9.5 1022 Am2. This corresponds to a mean value of 7.6 1.4 1022 Am2, which is higher than the average VDM value for late Miocene. Altogether our data suggest the existence of relatively high geomagnetic field strength undergoing low fluctuations. These results support the theoretical suggestion about an inverse relationship between secular variation and local field strength as result of electromagnetic coupling between the solid inner core and liquid outer core, with the inner core tending to stabilise core convection, and hence the field, when intensity is high. Some fluctuation of absolute intensity was detected within the same directional group (DG) indicating that the intensity of the geomagnetic field varies faster than its direction. " 2002 Elsevier Science B.V. All rights reserved.",,,,,,"10.1016/S0031-9201(02)00096-1",,,"http://hdl.handle.net/20.500.12104/43473","http://www.scopus.com/inward/record.url?eid=2-s2.0-0037191693&partnerID=40&md5=4e54fabefcf2b5ee4ce3f29d7730ec7c",,,,,,"01-feb",,"Physics of the Earth and Planetary Interiors",,"71 88",,"134",,"Scopus WOS",,,,,,"Mexico; Miocene; Paleointensity; Paleosecular variation",,,,,,"Paleosecular variation record of geomagnetic full vector during late Miocene, from the Nayarit area, Mexico",,"Article"
"44181","123456789/35008",,"Calvo Vargas, C.G., Departamento de Farmacología, División de Ciencias Básicas, Universidad de Guadalajara, Mexico; Ríos, V.P., Unidad de Investigación Clínica, Hospital Civil Juan I Menchaca, Universidad de Guadalajara, Mexico; Flores, A.M., Centro de Salud Rancho Nuevo, Mexico",,"Calvo Vargas, C.G. Rios, V.P. Flores, A.M.",,"2002",,"Tendency of coronary mortality to occur about 10 years later in women than in men is a well known fact. This difference has been attributed to the presence of estrogens in women. Despite the performance of many experimental and observational studies on the heart-protecting effect of estrogens, there are a lot of methodological limitations which make it difficult to obtain definitive results. This revision, shows the experimental studies where it has been demonstrated that estrogens do not increase cardiovascular protection. Emphasis is focused on adverse effects, such as the development of breast and endometrial cancer. It is also emphasized that during menopause, a series of life style modifications can be implemented, such as exercising, stop smoking and loosing weight. Undoubtedly, the results will be cardiovascular health benefits, with minimum integral health risks. " 2006 Federación Mexicana de Ginecología y Obstetricia.