Determination of strontium in milk by flame atomic absorption spectrometry

The method for the determination of Sr microamounts in milk by flame atomic absorption spectrometry (FAAS) is suggested. The main characteristics for the determination of this metal have been optimized and investigated: optimum air and gas pressure; the influence of hydrochloric acid and an effect of time on the absorbance of strontium. The selectivity of the determination of strontium was also investigated. The limiting interfering Sr/M ratios (the determination error ±10%) have been estimated. The suggested technique is simple, fast, accurate and selective

Expression of cytoplasmic islet cell antigens by rat pancreas.

A major problem in standardization of the islet cell cytoplasmic antibody (ICA) assay is variation in sensitivity of the different human pancreas substrates used in individual laboratories. To circumvent this problem, we have developed an assay that utilizes Wistar-Furth rat pancreas as substrate, an anti-islet monoclonal antibody (A2B5) to identify islets and fluorescein-conjugated protein A to identify patient autoantibodies. Sera from 85 control subjects, 27 type I diabetics, and 17 subjects at high risk for developing type I diabetes were assayed in parallel with our standard ICA assay on human pancreas substrate and with Wistar-Furth rat pancreas as substrate. Two sera from control subjects (2 of 85) were ICA positive with rat pancreas compared to 1 of 85 with human pancreas substrate. Sera from 11 of 27 type I diabetics and 15 of 17 sera from high-risk subjects were ICA positive with either rat or human pancreas substrate. A correlation between the specific islet fluorescence readings on human and rat pancreas sections was found with sera from high-risk and control subjects. Furthermore, end-point titers of an ICA-positive serum were identical with both assays. Finally, incubation of an ICA-positive serum with glycolipids, extracted from either human or Wistar-Furth rat pancreas, blocked subsequent ICA binding. These findings suggest that Wistar-Furth rat pancreas expresses an identical or similar autoantigen to human pancreas

Environmentally benign fabrication of calcium hydroxyapatite using seashells collected in Baltic Sea countries: A comparative study

<p>In this study, high purity crystalline calcium hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂; CHAp) was fabricated from seashells collected in different regions of the Baltic Sea using an environment-friendly water-based sol-gel synthesis route. The phase composition of the synthesized CHAp powders was studied by X-ray diffraction analysis and Fourier transform infrared spectroscopy. The surface morphologies of the precursors and synthesized samples were examined by scanning electron microscopy. A single shell type, Macoma balthica (L.), was collected from various locations around the Baltic Sea. Nevertheless, the resulting CHAp powders had surprisingly large variations in the surface morphology of sol-gel-derived CHAp bioceramics.</p