Chronic Experiment

Chronic Experiment

 

in physiology, a prolonged study of the life processes of a healthy experimental animal or of one specially prepared for analysis by being subjected to appropriate treatment or surgery.

There are several methods of physiological surgery. Artificial access to internal organs may be effected, for example, by creating a fistula for sham feeding. Individual organs are extirpated in order to study subsequent disturbances in the organism, and innervation is altered by denervation and the suturing of nerves. Other methods of physiological surgery include altering the blood supply by means of anastomosis, and registering bioelectric activity by implanting electrodes in the brain or heart.

Chronic experiments are conducted after the complete restoration of the physiological functions that were altered by anesthesia or surgery. Chronic experiments have a number of advantages over acute experiments, in which the experiment is conducted during surgery itself or immediately afterward. A classical example of the chronic experiment is the experiment conducted after the creation of an isolated pouch (Pavlov’s pouch).

G. N. KASSIL’

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africana rats were divided into 7 groups as in the chronic experiment with each group containing 5 rats.
A chronic experiment was performed in which animals remained either unsubstituted on soy free chow or were substituted with [E.sub.2] or the special BC extract BNO 1420 immediately after ovx.
To test such SERM activities of the BC extract BNO 1420, acute and chronic experiments in ovariectomized (ovx) rats were performed.
With these instruments we tested the special BC extract BNO 1420, the BC-derived isoflavone tectorigenin and [E.sub.2] in acute and chronic experiments for desired estrogenic effects in the hypothalamus and in the bone and compared these effects with those in the uterus and in the mammary gland.
In chronic experiments the parameters of chronic toxicity and embryotoxicity of compounds in a single seeding of the parental generation (P) and the constant seeding of Daphnia in a number of generations (P-F1-F2-F3) were determined in terms of "survival" and "fertility".
Ovariectomized mice were implanted with a control pellet or a pellet containing pesticide or 17[beta]-estradiol as in the chronic experiments. After a 4-week period, the mice were euthanized, and estrogenicity of the doses was determined by measurement of wet uterine weight.

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