Sialidases diseases involving

The discovery of a number of metabolic diseases involving defective sialic acid metabolism, partially due to sialidase activity deletion or reduction, has been invaluable in pinpointing areas of importance for future study. These disorders called sialidoses are discussed in chapter K. 

Because sialoglycoconjugates are essential components of cells and body fluids, and are frequently involved in specific, biological functions, sialidases may become toxic enzymes when present in non-physiological amounts. On the other hand, absence or lessening of the normal amount of this enzyme may lead to diseases, as became evident in studies of some fonns of mucolipidoses and sialidoses, respectively. 

Sialic acids, which are present in cell membranes and mucous secretions, are thought to allow viruses and other substances to enter cells. Serum sialic acid levels have been shown to increase in certain disease states such as cancers, rheumatic diseases, other inflammatory diseases, and infections (Anonymous, 1993). Elevated serum sialic acid levels have also been found in men with coronary artery disease and type II diabetes mellitus (Pickup et al., 1995). It has been hypothesized that inhibition of the enzyme sialidase, which is involved in the formation of sialic acid, could be of therapeutic importance (Anonymous, 1993). 

Since sialic acids are involved in so many important physiological processes in animals and man (section 10), the flooding of a tissue or the whole organism with bacterial sialidases is potentially disastrous, leading to acute and chronic diseases. 

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