This photo appeared in the Bulletin, November 18, 1991. The text was:

"New disease research system

A new approach to use of immunocytochemistry in medical research, being developed in the Faculty of Medicine, is expected to lead to a better understanding of the causes of some diseases.

Installation of a cryo-ultramicrotomy system worth $161,000 in the laboratory of Dr John Heath, in the Medical Sciences Building, has alleviated a major problem which faces researchers who use immunocytochemistry.

The cryo-ultramicrotomy system was paid for by an anonymous donor. The Research Committee of the Faculty of Medicine selected Dr Heath as the recipient of the donation after the committee had considered a number of applications for grants for the research equipment.

The cryo-ultramicrotomy system is the only system of its kind in the Hunter Valley and one of few in Australia.

The cryo-ultramicrotomy technique enables researchers to overcome a major technical limitation on the effectives of immunocytochemistry when combined with an electron microscope.

Dr Heath, a member of the University's Neuroscience Group, explains that immunocytochemistry permits a specific molecule to be located and visualised at the cellular, or sub cellular, level of microscopy.

In essence, the technique requires an antibody to develop against an antigenic site on the molecule.

Dr Heath says a "visual label" - a coloured or fluorescent dye or a micro-gold particle - is attached to the antibody, thus blinding the antibody to the antigen and revealing the molecule's lactation.

"Not surprisingly" immunocytochemistry has enabled major advances to be made in our understanding of disease processes and the function and development of cells and tissues," he says.

He mentions as example multiple sclerosis, other demyelinising diseases of the nervous system, Alzheimer's disease and Parkinson's disease, which affect nerve cells of the brain, muscle disorders, such as muscular dystrophy, disorders affecting the lungs and kidneys and the study of cells and tissues affected by cancer.

Dr Health explains that the use of electron microscopy in immunocytochemistry is highly desirable, because, through the high magnification and resolution achieved by the technique, the location of the molecule can be pin-pointed accurately at the sub-cellular level.

"Thus, it can be determined whether the molecule is present in one, or both, of two closely adjacent cells, or two closely opposed, buy functionally distinct, membrane systems.

"The synthesis and processing of the molecule within the cell can be followed and the nature and location organelles involved in storage and secretion can be determined.

"By using markers of different sizes, the interrelationship of different specific molecules can be follower in developing and mature cells and the response of these cells to disease can be monitored directly."

Dr Heath points out that the technical limitation on immunoytochemistry at the electron microscopy level stems from the need to expose the tissue to more reactive aldehydes, especially glutaraldehy, in order to preserve it.

As a result, he says, the natural antigenicity of the tissue is reduced, and often completely lost. Thus, antigen-antibody blinding is reduced, resulting is misleading reduction, or absence of localisation, in the tissue.

For this reason, the interpretations of many previous studies have remained controversial, or, at least incomplete.

By contrast, Dr Heath says, cryo-ultramicrotomy preserves the tissue structure by snap-freezing it in liquid nitrogen.

The antigenicity of the tissue is protected and the sensitivity of the crucial antigen-antibody reaction is increased, thereby, strengthening the quality and interrelationship of experimental results.

The immunocytochemical procedure is undertaken directly onto the thin sections of tissue (70 nanometres thick - one millimetre equals one million nanometres) that are generated by the cryo-ultramicrotome, which operates at a temperature of approximately minus 100 degrees C.

"The sections of tissue are examined directly by transmissions electron microscopy, using minute particles of gold - as little as one nanometre in diameter - as the visual marker of the site antigen-antibody reaction."

He says the equipment package includes a cryo-preparation unit, which ensures that the rate of freezing of the tissue is optimal. This is important, so that the formation of ice crystals can minimised thus improving the quality of the thin sections of tissue, as well as the ultrastructural integrity of the tissue.

Dr Heath, referring to the work in progress which uses the cryo-ultramicrotoy system, says included are experimental studies of the interactions of Schwann cells and macrophages during Wallerian degeneration of myelinated peripheral nerve, the post-translational processing of the placental hormone Corticotrophin Releasing Hormone and molecules involved in neuronal maturation.

Drs Gerald Little, Minjie Lin, Kate Jones, Lynne Hartley and Assoc Professors Roger Smith and John Rostos are also involved in the work"

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