Lysosomal Enzyme Content Research Articles

Histochemical, Metabolic and Ultrastructural Studies of the Maturation Zone of the Rachitic Rat Epiphyseal Plate

Histochemical, autoradiographic, and electron microscopic studies of the maturation zone in the epiphyseal plate of rachitic rats showed a failure of synthesis of polysaccharide and hence of matrix production, a delay in transport of the synthesized macromolecules without alteration in lysosomal enzyme content, and ultrastructural changes consistent with the observed metabolic abnormalities. It is suggested that the principal defect in the maturation zone of the epiphyseal plate of rachitic rats may be a local deficiency in the high energy phosphate required for metabolic activity.

Release of lysosomal enzymes in experimental inflammations; Effects of anti-inflammatory drugs

Lysosomal enzyme content (acid and alkaline phosphatases, N-acetyl-β-glucosaminidase, β-glucuronidase) of perfusates from rat paws was determined at various time intervals after induction of nystatin and carrageenin inflammation. In nystatin-induced inflammation, there was a significant increase in the lysosomal enzyme content of the perfusates which paralleled development of oedema. Such a release is dependent on the availability of leucocytes, since in rats made leucopenic by methotrexate administration a significant correlation was observed between the number of blood leucocytes and the concentration of lysosomal enzymes in the perfusates obtained from inflamed paws. The release of lysosomal enzymes was inhibited in decreasing order of potency by dexamethasone, azapropazone, indomethacin, betamethasone (administered in doses roughly equipotent in inhibiting oedema development). Phenylbutazone, prednisolone and aspirin were completely inactive in this respect.

Altered Morphology and Increased Acid Hydrolase Content of Alveolar Macrophages from Cigarette Smokers.

Excerpt The morphology and lysosomal enzyme content of human pulmonary alveolar macrophages from nonsmokers and from cigarette smokers were investigated. Alveolar macrophages were obtained by bronc...

Phagocytic potential of pulmonary alveolar epithelium with particular reference to surfactant metabolism.

Finely divided thorium and carbon were injected into the rat lung via the trachea and their uptake was studied electron microscopically. Small amounts of thorium were found in the lamellar vacuoles of the granular pneumocytes. Their presence was maximal at 24 hours and they later disappeared from these cells. This phenomenon is thought to represent a passive inflow as the vacuoles open on to the alveolar surface to discharge their content of surfactant, rather than evidence that the granular pneumocyte is concerned in surfactant disposal. An explanation reconciling the secretory nature of the vacuoles with their previously demonstrated content of lysosomal enzymes is advanced. Small quantities of thorium dioxide were ingested by the squamous pneumocytes and a little transferred to interstitial macrophages, but this is a minor route of disposal, the bulk of the material being ingested by alveolar macrophages. The limited phagocytic potential of the alveolar epithelium contrasts with that of the alveolar macrophages and is not taken to support the concept of an epithelial derivation of alveolar macrophages.

Effect of 6-mercaptopurine on enzymes of the polymorphonuclear leuocyte.

SummaryMononuclear cell infiltration of an egg albumin-induced skin lesion is preceded by infiltration with polymorphonuclear cells. In rabbits in which mononuclear cell infiltration of this lesion was suppressed by 6-MP, the possible effects of immunosuppression on the lysosomal enzyme content of the polymorphonuclear cells was investigated. The acid phosphatase, beta glucuronidase, and ribonuclease content of extracts of the polymorphonuclear cells of these animals were determined. In spite of adequate suppression of mononuclear infiltration of the induced skin lesion, no difference in the concentration of the three enzymes in the polymorphonuclear cells was noted. The results indicate that the failure of mononuclear cell infiltration in 6-MP-treated animals is not due to an effect on lysosomal enzyme synthesis in cells of the neutrophil series.

Response of Isolated Leukocyte Lysosomes to Gamma Irradiation

The recognition of the lysosome as a distinct intracellular structure has been followed by several attempts to elucidate the possible role of this organelle in the production or exacerbation of cellular radiation damage. The lysosome is a natural subject for such investigations, since it is essentially a depot of hydrolytic enzymes segregated from the rest of the cell by a single bounding membrane. The properties of lysosomes have been recently reviewed (1). Studies of the lysosomal enzyme acid phosphatase in cells collected from the peritoneal cavity of rats bearing induced peritoneal exudates 1 to 10.5 hours after whole-body X-irradiation (800 R) indicated an increase in the amount of this enzyme and suggested the possibility of lysosomal damage. Other cells and tissues of irradiated animals have also been found to possess slightly increased or labilized lysosomal enzyme content (2-9). The interpretation of these results is often complicated, however; there is evidence that the apparent increase in enzyme activity observed after whole-body irradiation may be the result of changes in cell population within certain tissues (10), destruction of lymphatic tissues (9), or increased endocrine activity (7). In the case of the peritoneal cell study cited above, the analysis is further complicated by the occurrence of early postirradiation changes in the net permeability of blood vessels in or bordering on the peritoneal cavity.2 Investigations of isolated lysosomes have not provided a complete answer to the question of the extent of lysosomal involvement in cellular radiation effects. Although high doses are usually required to elicit release of hydrolytic enzymes in vitro (11), lysosomes isolated from different tissues respond differently to ionizing radiation. Lysosomes isolated from rat liver showed increased reaction with enzyme

Total acid phosphatase content of peritoneal leucocyts obtained from 1-triiodothyronine treated guinea pigs.

Guinea pigs were injected with 1-triiodothyronine in doses ranging from 10 μg to 25 μg daily over 4 weeks of treatment. Assay of acid phosphatase content of peritoneal leucocytes performed at the end of that time revealed a significantly greater quantity of this lysosome-bound enzyme in peritoneal exudate cells of treated animals as compared with controls. It is suggested that the enhanced bactericidal activity of reticuloendothelial cells in 1-triiodothyronine-treated animals may be related to an increased cell content of lysosomal enzymes, including acid phosphatase, with resultant functional increases in the cytopeptic activity of these cells.