The effect of serum from non-diabetic patients, diabetics without neuropathy and diabetics with significant neuropathy on the ability of pig brain microtubule proteins to polymerize in vitro to microtubules was observed. The extent of polymerisation on the second and third cycles of polymerisation was significantly reduced in the presence of diabetics' serum compared with non-diabetics' serum. No significant difference between the serum samples from diabetics with and without neuropathy could be found. The finding suggests the presence of a factor in the serum of diabetics, whether or not they have neuropathy, which will impair microtubule formation in vitro.
Reversal of aluminium inhibition of enzymatic O-methylation by desferrioxamineThe paper' by Mason and Weinkove' confirms our experience with alumina extraction of catecholamines, We are especially interested in renal dopamine and have therefore been measuring this catecholamine in urine using a modification of the method described by Da Prada and Zurcher' which depends on O-methylation by catechol-O-methyltransferase (COMT). Our method of extraction is based on that described by Anton and Sayre' and is broadly similar to that described by Mason and Weinkove. However, acetic acid (0·2 moUI) is used to elute dopamine from the alumina, rather than hydrochloric acid.No problems regarding inhibition of COMT were encountered, presumably due to the relatively large quantity of dopamine in urine, until a new batch of alumina was obtained. Activity of COMT was greatly reduced in alumina-extracted samples and fn;e aluminium ions were suspected of causing the inhibition. Aluminium ion concentration, measured by furnace atomic absorption, was found to vary between 1·5 and 4·1 parts per million. Desferrioxamine was therefore added to the reaction mixture to chelate the free aluminium ions. However, we anticipated that an increased concentration of magnesium ions would be required for satisfactory O-methylation of dopamine. The concentration of magnesium ions in the final reaction mixture was increased from 6·6 mmoUI to 130 mmol/l, With these modifications satisfactory enzymatic activity was obtained when the concentration of desferrioxamine in the reaction mixture was 50 mmol/l. Batch-to-batch variability in the efficiency of extraction of activated alumina has been described by Anton and Sayre.' Our experience appears to indicate that there may also be batch variability in the quantity of aluminium ions going into solution in dilute acid during elution of adsorbed catecholamines. We can also go a little further than Mason and Weinkove, and suggest that a higher desferrioxamine concentration can be used provided sufficient magnesium ions are available. These modifications should improve the reliability of radioenzymatic assay of catecholamines using COMT after prior extraction with alumina. IF CASSON
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.