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A Moretto

Publications and source records attributed to A Moretto.

58 records · Page 4Linked to original sources
PubMedDate not supplied

Distribution and some biochemical properties of rat paraoxonase activity.

The calcium-dependent enzyme activity which hydrolyzes the p-nitrophenyl-O-P bond of paraoxon (paraoxonase) has been studied in several rat and human tissues. Rat plasma and liver showed the highest activities (1.31 +/- 0.19, 0.82 +/- 0.09 nmol/min mg protein +/- SEM, respectively), while other tissues showed less than 2% plasma activity. The Arrhenius plot showed monophasic patterns in both tissues with activation energy values of Ea = 57 +/- 3 and 69 +/- 4 kcal/mol degree K for rat liver and plasma, respectively. Rat plasma and liver paraoxonase lost about 80% activity after 24-hr storage at 27-30 degrees C and was not restored by calcium addition. There was no loss of activity in human serum after 3 days and only 33% after 5 days. The pH optimum for paraoxonase activities was about 7.4 for both rat tissues. It is concluded that plasma paraoxonase is similar to the liver enzyme and is a good mirror for total body detoxifying activity.

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PubMedDate not supplied

Promotion of peripheral axonopathies by certain esterase inhibitors.

Certain esterase inhibitors were found to exacerbate the clinical signs of polyneuropathy caused by various neurotoxic compounds and to delay the recovery from nerve crush. This phenomenon is referred to as promotion of axonopathies. The molecular target of promotion has not yet been identified. However, all known promoters are also inhibitors of neuropathy target esterase (NTE), the putative target of organophosphate neuropathy, but it has been shown that the target of promotion is unlikely to be NTE. Available data suggest that promoters might affect a target and a mechanism present in the nervous system that is not activated by axonal lesions. Promotion may be important to understand the physiological mechanism of nerve damage and repair. This finding also implies a changing perspective for the risk assessment of exposures to esterase inhibitors, some of which are used as pesticides and might be promoters.

Animals↗
PubMedDate not supplied

Neuropathy target esterase is not reduced in neural tissues of diabetic rats.

Marked (greater than 70%) reduction of the neuropathy target enzyme (NTE) shortly after exposure to organophosphorus compounds heralds the onset of delayed neuropathic damage in animals and humans. One previous study reported that lymphocyte NTE from diabetic patients was depressed by greater than 70%; such a reduction was considered to be a biological marker of diabetic polyneuropathy. To ascertain whether NTE from target tissues might be involved in diabetic neuropathy, we measured NTE activity in the brain, spinal cord and peripheral nerves of streptozotocin-diabetic rats. No reduction in NTE activity was detected in these neural specimens. Therefore, it is concluded that NTE is not involved in diabetic nerve damage and that the meaning of low NTE activity in peripheral lymphocytes of diabetic patients remains unclear.

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