Kwashiorigenic diet and diazinon toxicity

Sex- and organ-specific toxicity in normal and malnourished rats fed thermoxidized palm oil

The effects of free radical toxicity as induced by chronic consumption of thermoxidized palm oil (TPO) diet on organ size of normal animals, their first filial offspring and malnourished rats, were studied. Tissue- and sex-specific toxicity was revealed. The TPO diet significantly (P<0.01) reduced lung and kidney mass in normal male rats but female rats remained unaffected. Hearts of first filial offspring of both male and female rats were, however, enlarged while lung, liver and kidneys of first filial female offspring were additionally reduced in size (P<0.01). This information suggests that the observed toxicities could be cumulative for female offspring. Malnutrition protected against toxic injury because none of the kwashiorkoric animals rehabilitated on the toxic diet showed any overt symptoms of toxicity.

Nitrosamine metabolism in kwashiorkor rats

The in vitro metabolism of nitrosodimethylamine (NDMA) was studied in liver tissue obtained from male weanling kwashiorkor wistar rats. The elimination of this compound and that of nitrosomorpholine (NMOR) from the blood, after a single intravenous dose, was also investigated. N-demethylase activity in liver microsomes of the test animals was not significantly different from that of the controls although the activity of this enzyme per gram wet liver tissue was considerably reduced in the model animals. On the other hand, the glutathione (GSH) content in liver cytosol of the kwashiorkor animals was much higher than that of the controls. The elimination of NDMA and NMOR from the blood of the experimental animals over 8 hr following i.v. administration of the carcinogens, showed that the clearance rate of each nitrosamine was significantly lower in the kwashiorkor rats.

Possible defect in xenobiotic activation before glycine conjugation in protein-energy malnutrition

1. [14C]Benzoic acid administered to rats fed a normal diet was excreted mainly (99% of 24h excretion) as hippuric acid. 2. In protein-energy malnourished rats, only about 74% of [14C]benzoic acid administered was excreted as hippuric acid. The remainder was excreted as the glucuronide conjugate. 3. The oxidative phosphorylation capacity of liver mitochondria of malnourished rats was 30% less than that of normal rat liver mitochondria. 4. The decreased rate in oxidative phosphorylation is discussed in relationship to the observed decrease in glycine conjugation.

Gastrointestinal metabolism and transport of pesticidal carbamates

Published evidence pertaining to gastrointestinal absorption and metabolism of pesticidal carbamates will be reviewed. The major body of evidence will come form investigations conducted by the author on N-methylcarbamate pesticides with rats; few investigations directly involving the gastrointestinal system have been reported by other research groups. Results derived from in vitro and isolated in vivo preparations show that pesticidal carbamates are absorbed and metabolized by gastrointestinal tissues. Numerous gastrointestinal metabolites have been separated; some have been identified and their behavior in the gut characterized; these data will be included in the review to the extent they have been published. The absorptive and metabolic capacities of the gastrointestinal system vary from one region to another. The author draws from evidence obtained from in vitro and in vivo studies and proposes the events that occur between carbamate ingestion and the appearance of the compound and/or its metabolites in the portal blood or mesenteric lymph. In this endeavor, the author acknowledges that superimposition of the metabolic precursory substrate-product sequence on the sequential physiologic steps from ingestion to defecation produces a complex situation which is difficult if not impossible to study meaningfully by investigation of one tissue component at a time (i.e., epithelial uptake, epithelial metabolism, mucosal to serosal transport, etc.).

The metabolic fate of [14C] benzoic acid in protein-energy deficient rats

The metabolic fate of [14C] benzoic acid administered i.p. to marasmic-kwashiorkor rats has been investigated. Rats fed a normal diet with benzoic acid administered i.p. at 200 mg/kg, excreted the benzoic acid mainly as hippuric acid (99% of 24 h excretion), while marasmic-kwashiorkor rats excreted 62--85% as hippuric acid and 14--37% as the glucuronide conjugate. 2 weeks after repletion metabolism of benzoic acid by the marasmic-kwashiorkor rats on the stock diet had returned to normal; most of the benzoate was excreted as hippuric acid.

Toxicological evaluation of dietary diazinon in the rat

Female wistar rats were fed a semi-purified diet containing either no pesticide or 0.1 to 15 ppm diazinon for up to 92 days. At specified times, animals were bled from the orbital sinus to facilitate measurement of plasma and erythrocyte cholinesterase activity using a highly sensitive radiometric assay. Additional rats were sacrificed to determine brain acetylcholinesterase activity. General nutritional parameters measured included body weight gains and feed consumption during the growing period. Feeding diazinon at the levels employed produced no visible toxic manifestations. Treated animals showed weight gains and feed consumption which were comparable to appropriate controls. Feeding trials up to 90 days revealed that rats were highly sensitive to diazinon after 31 to 35 days exposure, as judged by reduction of plasma and erythrocyte cholinesterase activities. Brain acetylcholinesterase was judged to be insensitive to dietary diazinon (1.0 to 15 ppm), although moderate reduction (by 6%) of brain enzyme activity was noted among animals fed 10 ppm diazinon at Day 92. For all feeding trials, plasma cholinesterase was a more sensitive indicator of diazinon toxicity compared to erythrocyte or brain acetylcholinesterase. The 'no effect' level of diazinon for the rat was judged to be 0.1 ppm in the diet, which translates into an equivalent daily intake of 9 micrograms/kg body weight/day. This 'no effect' level is 20- to 50-fold lower than levels reported elsewhere in the literature, which may be attributed, in part, to the use of female animals in the present studies.

Interactions between nutritional factors and drug biotransformations in man

This study was undertaken to examine the influence of nutritional factors on the activity of the mixed function oxidase system in man, which is cytochrome P-450 dependent. Three normal volunteers were fed a low carbohydrate-high protein diet for 2 weeks, followed by a high carbohydrate-low protein diet for the follwoing 2 weeks. At the end of each test diet period, the plasma elimination rates of antipyrine and theophylline were determined. The mean plasma half-life for antipyrine was 17.5 hr on the high carbohydrate-low protein diet and 9.2 hr on the low carbohydrate-high protein diet. The mean plasma half-life for theophylline was 8.9 hr on the high carbohydrate-low protein diet and 5.9 hr on the low carbohydrate-high protein diet. These data demonstrate marked influences of dietary carbohydrate and/or protein ingestion on oxidative biotransformation of drugs in man.

[Interactions between nutrition and drugs]

It is only recently that the question of interaction between nutrition and drugs has been investigated. Generally there are two ways by which such an interaction may occur. On the one hand the food-intake and its composition may influence the effects of drugs by altering their pharmacokinetics. In most cases the abosrption of drugs and thereby also their biological effects are decreased when they are taken together with food, by only a few drugs the opposite effects have been observed. Furthermore the biotransformation of drugs may be inhibited by giving a diet poor in proteins. A diet rich in meat or in vegetables may also influence the urine pH in the more acid or basic direction and in this way the renal excretion of drugs may be changed considerably since drugs are generally either weak organic acid or bases. On the other hand drugs may also interfere with the availability and utilization of certain nutrients e.g. vitamins, electrolytes or trace elements. Such interaction could be observed when giving for example antibiotics, alcohol, contraceptives, anticonvulsives or laxatives over a long period. Deficiency of certain nutritional factors or even diseases can then be the consequence of such interactions.