Elevation of blood keto acids in cerebrocortical necrosis.

Values of various alpha-keto acids in whole blood were determined from cases of cerebrocortical necrosis (CCN), a thiamine deficiency disease, and were compared with those from normal animals. Thiamine pyrophosphate is an essential cofactor in the decarboxylation of many alpha-keto acids and this was reflected in elevated values not only of pyruvic acid but of glyoxylic, alpha-keto glutaric, phenyl pyruvic and hydroxyphenyl pyruvic acids in the CCN cases.

Cerebral autofluorescence and thiamine deficiency in cerebrocortical necrosis.

A discrete pattern of autofluorescence of the cerebral cortex of ruminants suffering from cerebrocortical necrosis is seen under ultraviolet light. This offers a rapid and relatively simple aid to diagnosis of the disease. There is a clear correlation of the characteristic fluorescence with biochemical evidence of cerebrocortical necrosis in field material.

Diagnostic aspects of cerebrocortical necrosis.

Specimens from cattle and sheep suspected of having cerebrocortical necrosis (CCN) were studied. Rumenal contents were examined for thiaminase-producing bacteria. Thiaminase activity was assessed in rumenal contents. The thiamine concentration of liver, brain and heart was determined and erythrocyte transketolase assessed. Diagnosis in each case, whether positive or negative for CCN, was decided by histopathological examination. There was a substantial agreement between the biochemical findings and the histological diagnosis indicating that a provisional diagnosis may be made on clinical and biochemical data alone. The findings are discussed in relation to other diseases which have the same neuropathological features. Attempts to isolate thiaminase-producing bacteria, which may be implicated in the aetiology of CCN, were inconclusive.

Ruminant thiamine requirement in perspective.

Thiaminases play an important role in the aetiology of CCN being responsible for the state of thiamine-deficiency which is an essential feature of the disease, evidence for which is presented here. These studies have led to a greater appreciation of the role of thiamine and thiaminases in ruminant nutrition especially as ruminal thiaminase activity is not confined to clinically affected animals but is of wider distribution. The importance of thiaminases in intensive beef production and the possibility of the need for thiamine supplementation in the form of a thiaminase resistant derivative is discussed.

Nature of the autofluorescent material in cerebrocortical necrosis.

A distinctive autofluorescence under ultraviolet light has been observed in the cerebral cortex of young ruminants suffering from cerebrocortical necrosis. The fluorescence is intimately connected with structural elements of the brain and cannot be extracted into solvents by normal procedures. The work presented here shows it to be associated with a collagen-like material.