The influence of G.A. and LA.A. on the hydroxyproline content of cell walls was examined with reference to the concept of wall-bound protein as a cross-linking agent regulating wall extensibility. It appeared that the hydroxyproline-rich protein content of cell walls pf elongating cells from the stems of two pea varieties, Alaska and Rondo, differed remarkably. Inaccordance with Lamport's hypothesis, the dwarf variety (Rondo) had a much higher hydroxyproline content than the standard variety (Alaska). When G.A. was applied to the top of the slow growing dwarf variety, the growth rate increased until comparable to the standard variety and the hydroxyproline content of the cell walls decreased somewhat. However, no linear relationship between growth stimulation and decreased hydroxyproline content existed.Experiments performed with excised elongating pea stem segments, grown in a culture solution containing phosphate buffer, showed that the hydroxyproline content of the cell walls increased considerably during an incubation time of 24 hours. IAA strongly inhibited this increase while stimulating elongation. However, a solution containing IAA and sugar caused the greatest elongation but also the greatest formation of hydroxyproline. It was concluded that cell extension and the hydroxyproline content of cell walls are not necessarily inversely correlated.
Technetium-99m macroaggregated albumin ([99mTc]Tc-MAA) is an injectable radiopharmaceutical used in nuclear medicine for lung perfusion scintigraphy. After changing to a new batch of macroaggregated albumin (MAA), we saw unwanted uptake in the liver and spleen. The batch was therefore tested by both the supplier and us and we found it to comply with the requirements of the European Pharmacopoeia (Ph. Eur.). However, a simple comparison between the problematic batch and a batch supplied by another manufacturer showed that there was a significant difference. The quality testing showed a higher number of small particles in the problem encumbered MAA batch with unwanted in vivo uptake. In this article we present a simple method of testing for particle size of [99mTc]Tc-MAA, which gives a good indication of how the radioactive drug performs in vivo. We argue that the quality control method described in the Ph. Eur. should be changed. The changes will improve concordance between the laboratory analyzes and what is seen in vivo in human lung perfusion scintigraphy. Furthermore, we hope that the MAA suppliers without delay will replace their release procedure to be in accordance with the method described in this article.
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