PubMed · 8495292
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J E Aldrich, S S Samant. 1993. Technical note: an integrated phantom for HDR quality control.. https://doi.org/10.1259/0007-1285-66-784-363
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Ferritin (Ft) plays an important role in cellular iron metabolism. It can store substantial amounts of iron in a nontoxic soluble form. However, its ability to donate iron for cellular needs, in particular for hemoglobin (Hb) synthesis in human erythroid cells, is still controversial. We studied the role of intracellular Ft-iron in Hb synthesis and the involvement of lysosomal proteolysis in iron release from Ft. Ft-iron release and its subsequent incorporation into heme was investigated in normal human erythroid precursors developing in culture. Dual staining flow cytometry with antibody (Ab)-specific for Ft and for Hb showed a decrease in cellular Ft content in erythroid cells during their maturation. Cellular Ft-iron participation in heme synthesis was studied by labeling cells with 59Fe. Cells were incubated with 59Fe-labeled human diferric transferrin (Tf), then chased, and intracellular radioiron distribution between Ft and Hb was determined on subsequent days by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and/or Ft immunoprecipitation and heme extraction. On day 6, most of the 59Fe accumulated in Ft. Thereafter, a progressive decrease of radioiron in Ft and a corresponding increase of the label in Hb was observed. Inhibition of heme synthesis with succinylacetone caused radioiron to remain in Ft and prevented its redistribution. Addition of unlabeled diferric Tf to the culture medium did not prevent radioiron from appearing in Hb. Chloroquine repression of lysosomal function prevented radio-iron redistribution between Ft and Hb. Inhibition of proteolysis by chymostatin and/or leupeptin led to Ft-protein accumulation in the cells and also prevented radioiron transfer from Ft to Hb. The results of the present study suggest that intracellular Ft donates iron for heme synthesis and that proteolytic Ft degradation in a lysosomal-like compartment is necessary for iron release and its transfer to heme.
The inferior vagal ganglia contain the cell bodies of centrally projecting vagal afferent neurones. Using in situ hybridization-histochemistry with a combination of two antisense neuropeptide Y (NPY) oligonucleotides, we have demonstrated that a population of human inferior vagal perikarya express mRNA encoding prepro-NPY, the precursor of NPY. In vitro receptor autoradiography, using both [125I]Bolton Hunter-NPY ([125I]BH-NPY, 15 pM) and [125I]peptide YY ([125I]PYY, 25 pM), enabled visualization of NPY binding sites. Competition binding with NPY (1 microM), PYY (1 microM) and [Leu31,Pro34]NPY (100 nM), suggest that both Y1 and Y2 receptor subtypes are present on human vagal afferent neurones. These observations suggest a potential role for NPY in neuromodulation of vagal transmission in humans.
The observed total interlaboratory uncertainty in restriction fragment length polymorphism (RFLP) measurements is sufficiently small to be of little significance given current forensic needs. However, as the number of RFLP data increase, further reduction in the total uncertainty could help minimize the resources required to evaluate potential profile matches. The large number of data available enable quantitative estimation of the within-laboratory imprecision and among-laboratory bias contributions to the total uncertainty. Some small but consistent among-laboratory measurement biases can be attributed to specific procedural or materials differences. The bias direction is often fragment-specific and thus unpredictable for unknown samples. Actions that would minimize currently recognized sources of interlaboratory bias include the following: (1) all laboratories should use the same algorithm for data interpolation, (2) all laboratories should use the same sizing ladders, (3) each laboratory should prepare control DNA and sample DNA in the same manner and with the identical reagents, (4) all laboratories should adopt a uniform policy on ethidium bromide use, and (5) all laboratories should adopt the same control DNA sizing acceptability criteria.