Experimental production of diffuse pulmonary fibrosis and alveolitis in cattle: the effects of repeated dosage with 3, methyl indole

Specific toxins destabilize virus inhibitors (e.g. AIDS viruses)

There are two approaches to the study of viral infections - the A-Z hypothesis of Sprietsma involving thiol-zinc inhibition of protease activation in the virus coat, and the activity of toxins in depleting the cell of thiols, or the activity of toxins activating (not detoxifying) the mixed function oxidase (MFO) system. Both of these systems generate free radicals and utilize thiols in the process. Zinc forms stable mercaptides with thiols, inhibits cyclic reduction-autoxidation of thiols and superoxide generation. When the MFO system acts as an activator and not as a detoxifier in that intermediate products are more toxic than the original compound, zinc inhibits the oxidation. An example of increased toxicity with increased MFO activity is the toxin 3-methylindole (3-MI), a toxic product of intestinal bacterial putrefaction which reactivates the infectious bovine rhinotracheitis virus (IBR). Zinc reduces MFO activity and in this regard it functions synergistically with antioxidants in protecting cell membranes. It is hypothesized that stable zinc complexes inhibit activity of proteases in the virus nucleocapside (NC) proteins in the virus coat, both directly and indirectly because zinc also inactivates some toxins that are thiol depleters or virus reactivators.

Respiratory diagnostic pathology

Effective treatment and control of bovine respiratory disease is dependent upon an accurate diagnosis. This article discusses the approach to diagnosis of bovine respiratory disease from the perspective of respiratory pathology. Topics covered include necropsy examination of the respiratory system, sample collection and submission, and the gross, and histopathologic lesions of the upper and lower bovine respiratory system.

Sudden infant death syndrome. The role of putrefactive toxins in respiratory paralysis and cerebral coma

The Sudden Infant Death Syndrome (SIDS) is responsible for the death of 10,000 infants annually in the U.S.A. The cause of these deaths is not known; all SIDS infants studied died during sleep in a silent fashion and there are no specific lesions observable post mortem. It may be of significance, however, that nearly half of SIDS infants had a respiratory tract infection in the last two weeks of life while forty percent had bloody froth over their mouths when found, presumably pulmonary oedema fluid. It is hypothesis that improper feeding or diarrhoea may likewise be involved in SIDS and that enterotoxins from putrefactive products are the precipitating event in this syndrome.

Respiratory disease in adult cattle

This article discusses the nomenclature of respiratory disease, acute respiratory distress syndromes, hypersensitivity diseases, chronic respiratory disease, and the differential diagnosis of respiratory disease.

Kwashiorkor

Kwashiorkor kills millions of young children in the tropical Third World. It was believed to be a disease of protein starvation. The medical team headed by Professor Ralph Henrickse of the Liverpool School of Tropical Medicine has discovered that aflatoxin, a fungus toxin, may be the triggering factor in this disease which also impairs liver function. In New Zealand, we have a pasture fungus, the spores of which produce a liver toxin that has killed millions of animals this century and impaired the performance of millions more. New Zealand is a pastoral farming country with 70 million sheep and several million cattle. We now protect the animal with zinc medication. This paper describes the similarities between Kwashiorkor and the mycotoxic liver disease in New Zealand livestock, known locally as Facial Eczema. It describes briefly my discovery that pharmacological doses of zinc protected farm animals from pasture contaminated with the spores of the fungus Pithomyces chartarum, which contains the toxin sporidesmin. This paper proposes that Kwashiorkor and Facial Eczema are diseases with similar beginnings and a common end.