Papers by Ankie Schoenmakers
International Journal for Vitamin and Nutrition Research, 1989
The effect of dietary phosphorus (P) on calcium (Ca) and phosphorus metabolism was studied in you... more The effect of dietary phosphorus (P) on calcium (Ca) and phosphorus metabolism was studied in young female rats. P levels in the semipurified diets ranged from 0.1 to 0.4% (w/w). A level of 0.4% P in the diet is recommended for rats. Kidney calcification was observed in rats fed the 0.4%-P diet whereas P restriction prevented this condition. Rats fed the diet containing 0.1% P, showed severe hypercalciuria, hypercalcemia, reduced growth and impaired bone mineralization. These effects did not occur when the diet contained 0.2 or 0.3% of P. This study suggests that in short-term studies P in the diet of female rats can be restricted to 0.2% so as to prevent nephrocalcinosis without affecting their development.
Human & Experimental Toxicology, 1995
1. A method of continuous infusion in the unrestrained rat is described, which provides a scienti... more 1. A method of continuous infusion in the unrestrained rat is described, which provides a scientifically acceptable and easily maintained rodent model for use in toxicological investigations. 2. Sprague Dawley SPF rats had cannulas implanted into the vena cava via the femoral vein, and were continuously infused with physiological saline for a total of 28 or 90 days. 3. The results indicate that there was no change in body weight, food consumption, clinical observations or clinical biochemistry of infused rats when compared to non-infused rats. There were small changes in haematological parameters, however none were toxicologically significant. Urinary volume was increased and urinary specific gravity and osmolality were decreased. At macroscopic and microscopic examination there were findings of scar formation associated with the area of surgery and minimal irritation in the area of the vena cava which accommodated the cannula. 4. These results indicate that implantation of a cannula into the vena cava of a rat and subsequent continuous intravenous infusion of physiological saline produces no toxicological adverse effects over a period of 90 days. Consequently, this model can be recommended for the continuous intravenous administration of test substances to rats.
Food and Chemical Toxicology, 2014
Piperine is responsible for the hot taste of black pepper. Publications on genotoxicity of piperi... more Piperine is responsible for the hot taste of black pepper. Publications on genotoxicity of piperine are reported: negative Ames Tests and one in vitro micronucleus test (MNT). In vivo tests were mainly negative. In the majority of the data the administered dose levels did not follow the dose selection requirements of regulatory guidelines of having dose levels up to the maximum tolerated dose (MTD). The only oral high dose studies were a positive in vivo MNT in mice in contrast to a negative in vivo chromosome aberration test in rats. Thus, conflicting results in genotoxicity testing are published.
Regulatory Toxicology and Pharmacology, 2013
Short term toxicity studies are conducted in animals to provide information on major adverse effe... more Short term toxicity studies are conducted in animals to provide information on major adverse effects typically at the maximum tolerated dose (MTD). Such studies are important from a scientific and ethical perspective as they are used to make decisions on progression of potential candidate drugs, and to set dose levels for subsequent regulatory studies. The MTD is usually determined by parameters such as clinical signs, reductions in body weight and food consumption. However, these assessments are often subjective and there are no published criteria to guide the selection of an appropriate MTD. Even where an objective measurement exists, such as body weight loss (BWL), there is no agreement on what level constitutes an MTD. A global initiative including 15 companies, led by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs), has shared data on BWL in toxicity studies to assess the impact on the animal and the study outcome. Information on 151 studies has been used to develop an alert/warning system for BWL in short term toxicity studies. The data analysis supports BWL limits for short term dosing (up to 7 days) of 10% for rat and dog and 6% for non-human primates (NHPs).
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Papers by Ankie Schoenmakers