Quantitative microlocalization of diffusible ions in normal and @entity3649 XXXX @entity35 lens by secondary ion mass spectrometry.

@entity1568 @entity231 @entity990 @entity1372 @entity3649 @entity460 @entity972 @entity35 @entity28633 @entity6619
Secondary ion mass spectrometry (SIMS) is a surface analytical technique with high sensitivity for elemental detection and microlocalization capabilities within the micrometre range. Quantitative analysis of @entity990 resins and gelatin have been reported (Burns-Bellhorn _ File, 1979). We report here the first application of this technique to quantitative microlocalization in the context of a physiological problem--analyses of @entity1372 , @entity972 and @entity460 in normal and @entity3649 -induced @entity231 in @entity35 lens. It is known that during the development of @entity3649 -induced @entity231 the whole lens content of @entity972 is decreased, @entity1372 is increased and, in late stages, @entity460 concentration increases. Whether these alterations in diffusible ions occur homogeneously or heterogeneously is not known. Standard curves were generated from @entity990 resins containing known concentrations of @entity1372 , @entity972 or @entity460 organometallic compounds using the Cameca IMS 300 Secondary Ion Mass Spectrometer. Normal and @entity231 lenses were prepared by freezing in @entity28633 in a liquid @entity1568 bath followed by freeze-drying at -30 degrees C. After dry embedding in @entity990 resin, 10 microns thick sections of lens were pressure mounted on @entity6619 wafers, overcoated with gold, and ion emission measured under the same instrumental conditions used to obtain the standard curves. Quantitative analysis of an area 27 microns in diameter, or a total analysed volume of 1.1 microns3, was performed by using a mechanical aperture in the ion optical system. Ion images provided qualitative microanalysis with a lateral resolution of 1 micron. Control @entity35 lenses gave values for @entity1372 and @entity972 content with a precision of +/- 17% or less. These values were compared to flame photometry and atomic absorption measurements of normal lenses and were accurate within 25%. Analysis of serum and blood also gave accurate and precise measurements of these elements. Normal @entity35 lenses had a gradient of @entity1372 , and, to a lesser degree, of @entity972 from the cortex to the nucleus. Development of @entity3649 -induced @entity231 was heterogeneous by morphological criteria, beginning at the lens equator and spreading from the cortex into the nucleus. However, the loss of @entity972 and increase in @entity1372 concentration occurred at early stages in both the cortex and nucleus cells, possibly because these cells are interconnected by gap junctions. There is a local alteration in elemental content prior to morphologically demonstrable @entity231 formation.(ABSTRACT TRUNCATED AT 400 WORDS)
