The changes in the absolute and relative contents of α- and ĸ-caseins, lactoferrin, α-lactalbumin, serum albumin and lysozyme in human milk have been studied through the period of lactation. Protein fractions of 209 samples were analyzed by a discontinuous poly-acrylamide gel electrophoresis method, β- and ĸ -caseins decreased from colostrum to mature milk although their relative percentages remained constant. They accounted for 12–15 and 9–13% of the total protein in human milk, respectively. Lactoferrin decreased in absolute and relative amounts with advancing lactation. This protein represented 32–19% of the human milk proteins. α-Lactalbumin slightly decreased from colostrum to transitional milk but there was an increase in mature milk by 16–30 days. The percentages of this protein in colostrum and mature milk were approximately 23 and 30%, respectively. Serum albumin also decreased with advancing lactation, but the differences between transitional and mature milk were not statistically significant. Lysozyme increased from colostrum to mature milk both in relative and absolute amounts. Colostrum contained about 262 µg/ml, and mature milk 1,246 µg/ml, representing 1.5 and 12.1% of total milk proteins.

The authors reinvestigate the relation between the Fourier transform of SEELFS (surface extended energy-loss fine structure spectroscopy) data recorded in the second derivative mode of the electron yield, and the radial distribution function F(R) of atoms around the emitter. This relation is not obvious since the Fourier transform is done over wavevector modulus and the derivation is done with respect to energy. They show that, providing a k3 weighting factor is introduced, an EXAFS-like (extended X-ray absorption fine structure) analysis leads to R2F(R) with a good accuracy. This gives an a posteriori justification of the treatment currently used in the literature. The reasoning is easily extended to the case of data recorded in the first derivative mode, for which RF(R) is obtained with a k2 weighting factor. It is also shown that the R2 (respectively R) (respectively R) factor must be eliminated to obtain shell positions with good accuracy, which is generally not achieved in previous work. All these conclusions are supported by a numerical analysis performed in the case of a model spectrum associated with the Ni(111)M23 loss spectra.

Actividad antiofídica y analgésica de Renealmia alpinia Contribución de los autores: Arley Camilo Patiño: pruebas de toxicidad aguda, actividad analgésica, actividad proteolítica, inhibición del efecto letal in vivo del veneno, electroforesis, tabulación y discusión de los resultados. Jésica López: preparación de extractos y fracciones, pruebas de actividad coagulante y hemolítica. Mónica Aristizábal: pruebas de toxicidad aguda. Juan Carlos Quintana: prueba de inhibición del efecto letal in vivo del veneno. Dora Benjumea: pruebas de actividad analgésica y estructura del artículo escrito.

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A high sensitivity Kerr magnetometer (ΔI/I = 1/30) is presented, making use of open source hardware and software. By making time resolved measurements (up to 0.15 s/cycle) the signal quality has been greatly improved up to an order of magnitude, enabling us to compare our measurements with commercial vibrating sample magnetometers. We also present an additional setup to amplify the Kerr signal in a 25:1 scale, cleaning a large part of the electronic and trigger noise.