Biomedical subjects

K R Rees

Publications and source records attributed to K R Rees.

49 records · Page 3Linked to original sources

PubMed1967

The action of aflatoxin B1 on the rat liver.

The administration of a single dose of aflatoxin B(1) to the rat (7mg./kg. body wt.) results in the slow development of a periportal necrosis. Hepatic enzymes are released into the serum in the second 24hr. of the poisoning, closely preceding the onset of the necrosis, which is followed by a rise in serum alkaline-phosphatase activity and bilirubin concentration. Aflatoxin B(1) has been detected in the nucleus of the poisoned liver cell and in vitro it has been shown to interact with DNA. The toxin inhibits the production of nuclear RNA, probably by preventing the transcription of DNA by the RNA polymerase. It is proposed that the interaction of the toxin with DNA gives rise to its inhibitory action on mitosis and its necrogenic action.

Aflatoxins↗

PubMed1967

The effect of the aflatoxins B1, G1, and G2 on protein and nucleic acid synthesis in rat liver.

A comparison has been made of the difference spectra obtained by causing various aflatoxins (B(1), G(1) and G(2)) to interact with calf-thymus DNA. The effect of these toxins on RNA and protein synthesis by rat-liver slices has been measured. The extent of their inhibitory action on the synthetic reactions was proportional to the degree of spectral shift obtained with their interaction with DNA. It is proposed that their toxicity depends on this interaction. It was demonstrated that the RNA polymerase of nucleoli isolated from the livers of aflatoxin B(1)-poisoned rats was inhibited. This finding is in agreement with the proposed mechanism for the hepatotoxic action of aflatoxin.

Aflatoxins↗

PubMed1967

The interaction of aflatoxins with purines and purine nucleosides.

From measurements of thermal hyperchromicity and the behaviour of an aflatoxin-DNA mixture on a Sephadex column it was concluded that aflatoxin B(1) is capable of weak binding to single-stranded DNA. The interactions of the aflatoxins (B(1), G(1) and G(2)) with nucleosides result in difference spectra and suggest that the purine bases and the amino group play a role in the binding of all the aflatoxins to DNA.

Adenine↗

PubMed1967

The hepatotoxic action of allyl formate.

The hepatotoxic action of allyl formate on rat liver has been investigated. Biochemical changes can be detected in the liver cell many hours before the histological changes and it would appear that the toxin has a direct action on the liver parenchymal cell. The results suggest that allyl formate is not the toxic agent but that it is converted via allyl alcohol into acrolein. This reaction requires the presence of alcohol dehydrogenase. Histochemical studies have shown that this enzyme is localized in the periportal region of the liver lobule, and may explain why allyl formate solely produces a periportal necrosis. As glutathione and 1,4-dithiothreitol protect against the early biochemical changes produced by the poison, it is probable that acrolein alkylates proteins and nucleic acids.

Alcohol Oxidoreductases↗

PubMed1967