Patricia D. Wilson

Enzyme Changes in Ageing Mammals

Enzyme changes in various organs of ageing mammals have been discussed, with particular reference to the limitations of the methods employed. Many enzymes have been reported to decrease, increase and remain constant in ageing, but many discrepancies exist. It was concluded that very complex patterns of change in enzymes with age exist, that combined biochemical and histochemical studies were desirable and that the old may represent a physiological elite. Bearing these limitations in mind, there may be a tendency towards a general decrease in mitochondrial respiratory enzymes in senescence.

Enzyme Patterns in Young and Old Mouse Livers and Lungs

Enzyme assays in young (3–10 days), adult (6 months), middle-aged (18 months) and old (30 months) male and female C57 and C3H (6 and 12 months) mouse livers and lungs revealed complex patterns of chan

'spontaneous' Neoplastic transformation in vitro. The ultrastructure of the tissue culture cell.

Abstract The ultrastructure of 11 tumour-producing and 13 non-tumour producing cell lines derived from different organs of young and old C57BL and C3H mice has been examined. In cultures from all organs examined (kidney, lung, bladder, tongue, heart, spleen, prostate, peritoneum and spinal cord) two predominant cell types were found. These cells had morphological characters suggesting that they may have been derived from endothelial cells and vascular pericytes. Cells in 7 11 tumour lines had cytoplasmic glycogen deposits but there were no other morphological differences between tumour and non-tumour lines from young and old mice, or between different transfer generations, or between lines derived from different mouse strains.

The Effect of Age on Mitochondrial Enzymes and Respiration

There was no significant difference between the levels of cytochrome oxidase and malate dehydrogenase in whole liver homogenates or in mitochondria isolated from the livers of 6-month-old and 30-month-old C57/BL mice. Little change with age was found in the cytochemical localisation of either enzyme. There were no significant changes in endogenous, state III or state IV respiration of mitochondria isolated from the livers of young and old mice.

Effects of Age on Rat Liver Enzymes

Hepatocytes, endothelial and Kupffer cells were isolated from young adult (3 month) and old (24 month) rat livers and the activities of some plasma membrane, endoplasmic reticulum, mitochondrial, lyso

The effects of age on total DNA and cell number in the mouse brain.

Total brain DNA, protein, wet and dry weight, and total number of nuclei were measured in animals from a colony of ageing C57BL mice. No significant differences were found in a series of animals from 4 to 158 weeks old.

Alkaline phosphatase phenotypes in tumour and non-tumour cell lines: not an invariable marker for neoplastic transformation.

The cytochemical localisation and presumed isoenzyme type (based on selective inhibition experiments) of alkaline phosphatase in 5 cell lines derived frrom normal human, rat, mouse and hamster tissues, 6 human lymphoblastoid lines and 6 human and mouse tumour-derived cell lines are described. Enzyme activity varied between the cell lines. An isoenzyme inhibited by L-phenylalanine was present in 3 normal lines, 3 lymphoblastoid lines and 2 tumour lines. The presence of this isoenzyme cannot be used as a marker of neoplastic transformation.

Alkaline phosphatase as a marker of transformation in adult mouse bladder epithelium after in vitro exposure to 7,12-dimethylbenz(a)anthracene.

Abstract Loss of alkaline phosphatase from bladder epithelium has been suggested as a specific preneoplastic change induced by chemical carcinogens in rats (Stiller and Rauscher 1971; Kunze and Schauer 1971; Kunze et al. 1975), and mice (Highman et al. 1975). Using an in vitro bladder epithelial cell transformation system established by treating primary cultures of mouse bladder epithelium from young adult and old donors with 7,12-dimethylbenz-(a) anthracene (DMBA) (Summerhayes and Franks in press) and electron microscope cytochemistry, the localisation of alkaline phosphatase was compared in normal mouse bladder, in epithelial cell cultures before and after transformation with DMBA and in tumours derived from implants of these cells in syngeneic mice.

Alkaline phosphatase in mitochondria

In electron microscope cytochemical studies alkaline phosphatase activity was present in the mitochondria of all liver cells and associated with the plasma membrane of the cells of bile canaliculi. The mitochondrial activity was partially inhibited by L-phenylalanine and Levamisole but the plasma membrane associated activity was completely inhibited by Levamisole. Biochemical assays have shown that a significant amount of the total mouse liver alkaline phosphatase activity was present in the mitochondria fraction. Starch gel electrophoresis showed that this mitochondrial alkaline phosphatase had a characteristic isoenzyme pattern, consisting of 3 distinct bands which were not retarded by neuraminidase treatment. The enzyme in the mitochondria-free supernatant showed one wide band which was retarded by neuraminidase.