Elucidation of the Fe(III) Gallate Structure in Historical Iron Gall Ink.

Synthetic, structural, spectroscopic and aging studies conclusively show that the main colorant of historical iron gall ink (IGI) is an amorphous form of Fe(III) gallate·xH2O (x = ∼1.5-3.2). Comparisons between experimental samples and historical documents, including an 18th century hand-written manuscript by George Washington, by IR and Raman spectroscopy, XRD, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy confirm the relationship between the model and authentic samples. These studies settle controversy in the cultural heritage field, where an alternative structure for Fe(III) gallate has been commonly cited.

Age-dependent association of gamma-crystallins with aged alpha-crystallins from old bovine lens.

PURPOSE: Previous theoretical and experimental studies have predicted that the loss of weak protein interactions between alpha- and gamma-crystallins could result in a decrease in the transparent properties of the aging lens. METHODS: alpha-Crystallins were prepared from the nucleus of old bovine lens, and gamma-crystallins were prepared from whole fetal bovine lens or from the nucleus of old bovine lens. The possible interactions of old alpha-crystallins with either old gamma-crystallins or fetal gamma-crystallins were quantitated at equilibrium using microequilibrium dialysis. The amount of each gamma-crystallin species in the "full" versus "empty" chambers was determined by reverse phase chromatography to obtain a binding ratio (full/empty). RESULTS: A binding ratio greater than 1.00 is indicative of a alpha-crystallin/gamma-crystallin interaction. Within experimental error (+/-2X standard deviation), there were no interactions between aged gamma-crystallins with aged alpha-crystallins while there were significant interactions between some of the fetal gamma-crystallins with aged alpha-crystallins. CONCLUSIONS: In the aged bovine lens, when transparency is known to decrease, there is no detectable interaction of gamma-crystallins with alpha-crystallins as measured by microequilibrium dialysis. The results are consistent with the hypothesis that short-range, weak, attractive interactions between alpha- and gamma-crystallins are necessary for maximum transparency of the lens.

Differential binding of mutant (R116C) and wildtype alphaA crystallin to actin.

PURPOSE: Quantitate the interaction of mutant (R116C) and wildtype human alphaA crystallins with actin. METHODS: AlphaA crystallins, expressed in a recombinant system, were purified, followed by passage through an actin affinity column. RESULTS: Binding of mutant alphaA crystallin was significantly less than binding of wildtype alphaA crystallin. CONCLUSIONS: The R116C mutation of alphaA crystallin found in human cataracts binds less to the cytoskeletal component actin. Since both alphaA crystallin and actin are necessary for proper development of the lens, decreased binding of the mutant protein to actin may perturb normal differentiation processes of lens cells which are necessary for transparency.

Role of short-range protein interactions in lens opacifications.

At high protein concentrations found in the lens, short-range order of lens proteins results in a medium of relatively constant protein density and refractive index that minimizes scattering of light. During aging and cataractogenesis of the lens, formation of high molecular weight aggregates causes fluctuations in this protein density, resulting in light scattering and a concomitant decrease in transparency, with eventual lens opacification. This review summarizes what is known about the molecular nature of short-range order, both in the normal and cataractous lens, then hypothesizes that part of this order involves heterologous crystallin interactions that may be necessary for the maintenance of lens transparency. A summary of past and possible future experimental approaches will be reviewed that can be used to ascertain the existence of these interactions and their possible changes during lens opacification.

Screening of crystallin-crystallin interactions using microequilibrium dialysis.

PURPOSE: It has been hypothesized that short-range, protein-protein interactions of crystallin are necessary for the maintenance of lens transparency. Because of their probable weak nature, it has been difficult to both detect and quantitate the nature of these interactions. To determine if interactions exist between alpha-crystallin and gamma-crystallin under true equilibrium conditions, we have used microequilibrium dialysis. METHODS: Total alpha-crystallin and gamma-crystallin were prepared from soluble proteins of fetal bovine lenses by HPLC and gel filtration chromatography. The proteins were added to one side of a microequilibrium dialysis cell, comprised of two chambers separated by a membrane with 100 kDa molecular weight cut-off. After reaching equilibrium, the amount of free gamma-crystallin and the amount of gamma-crystallin bound to alpha-crystallin was determined by HPLC and reverse phase analysis of both chambers. Selected gamma-crystallin that bound to alpha-crystallin was further purified by ion exchange chromatography, and then incubated with alpha-crystallin, to verify the specificity of their binding. RESULTS: Analysis of both microequilibrium dialysis chambers incubated at different times at 37 degrees C indicated that equilibrium was reached at 4 days. When total alpha-crystallin and gamma-crystallin were incubated for this time period, significant binding was observed between alpha-crystallin and the IIIA, II, and IVA species of gamma-crystallin. These interactions were confirmed by microequilibrium dialysis determinations containing alpha-crystallin and purified gamma-crystallin species. CONCLUSIONS: These results show that microequilibrium dialysis can be used to demonstrate significant noncovalent interactions of alpha-crystallin and gamma-crystallin under true equilibrium conditions.

Decreased association of aged alpha crystallins with gamma crystallins.

Previous studies have demonstrated non-covalent interactions of alpha crystallins with gamma crystallins, under true equilibrium conditions. These interactions could affect short-range interactions of lens crystallins that are necessary for the transparent properties of the lens. Since the transparent properties of the lens decrease during aging, it is possible that there are corresponding changes in the ability of aged alpha crystallins to interact with gamma crystallins. In the following study, alpha crystallins were prepared from fetal and aged bovine lenses, then tested for binding to gamma crystallins using microequilibrium dialysis. The results demonstrate that during aging of the normal bovine lens, there is a decrease in the ability of alpha crystallins to bind to gamma crystallins, consistent with the involvement of this interaction in the transparent properties of the lens.

Satisfacción de los usuarios externos(as), atendidos en la unidad de emergencia del Hospital Regional Santa Teresa Comayagua, Honduras: julio 2004

Identifica los principales factores y posibles causas que inciden en una satisfacción positiva o negativa de los usuarios externos (pacientes y acompañantes) que son atendidos en el servicio de emergencia de dicha unidad.