Lysosomal Acid Protease Research Articles

Isolation and characterization of the haemocytes of Calliphora vicina on density gradients of Ficoll

Discontinuous gradients of Ficoll have been used in an equilibrium density analysis of the haemocytes of Calliphora vicina. Using histochemical criteria, it was shown that the acid phosphatase-containing haemocytes decreased in mean density during larval life. Enzymatic analysis, and an analysis of the density distribution of labelled haemocytes at various times after an injection of [H 3]-thymidine, provided evidence that a dense, replicating population of cells had been separated from a non-replicating acid phosphatase-containing population. The latter gained increasing amounts of the lysosomal enzymes acid phosphatase and protease as they aged.

59 - Studies on the function of lysosomal acid proteinases: Purification and properties of the multiple forms of cathepsin D from rat spleen

59 - Studies on the function of lysosomal acid proteinases: Purification and properties of the multiple forms of cathepsin D from rat spleen

Effects of subclinical hydrogen sulfide intoxication on mouse brain protein metabolism

Exposure of adult female mice to 100 ppm hydrogen sulfide for 2 h resulted in a marked decrease in incorporation of labeled leucine in cerebral protein and myelin 24 and 48 h after the exposure. The reduced incorporation was accompanied by decreased lysosomal acid proteinase activity at the same time. The incorporation increased to the control level 72 h after the exposure whereas the lysosomal enzyme activity remained below the control range at the end of the follow-up period. The changes were distinct from carbon monoxide-induced changes and might have resulted from the inhibition of cerebral cytochrome oxidase activity. The delay of maximal effects to the third postexposure day might pose a potential toxicological hazard in repeated exposure to higher hydrogen sulfide concentrations.

Effect of carbon monoxide on protein metabolism in mouse brain

Thirteen adult male mice were exposed 1.5 h to air containing 0.3% carbon monoxide. Protein metabolism was studied after the exposure by the analysis of intraperitoneally injected labeled leucine and lysosomal acid proteinase activity in the cerebral homogenate. Cerebral myelin was isolated from the same animals. Biochemical changes were biphasic: Precursor uptake was initially high, dropped to within the control range at 30 h, and rose again 54 h after the exposure. Acid proteinase activity was higher than that in control homogenates at 54 h, and thereafter returned to the control range, as did the leucine uptake. The myelin label incorporation was at its highest at 30 h while the myelin protein content was at its lowest at the same time. Biochemical changes in myelin levelled off simultaneously thereafter. We concluded that increased acid proteinase activity may play an important role in recovery after carbon monoxide poisoning.

Effects of chronic styrene inhalation on rat brain protein metabolism

Adult male rats were exposed to 7.9 mumol/1 (300 ppm) of styrene for 2--11 weeks 6 h daily excluding Saturdays and Sundays. The exposures caused a marked styrene accumulation in brain and perinephric fat, and the accumulation tended to increase upto the 4th week. The body styrene content decreased thereafter gradually towards the end of the experiment to reach half of the styrene content of the 4th week. Serum creatine kinase activity increased at the initial stage of the exposures while serum non-specific cholinesterase was below the control range at the same time. Earliest biochemical changes were detected at the 9th week of exposure, and they included increased activity of lysosomal acid proteinase. Increased enzyme activity prevailed to the end of the exposures. Simultaneous minor alterions could be detected in spinal cord axonal protein pattern whereas water-soluble protein composition in cerebellum did not change. Biochemical alterations in brain were not accompanied by significant changes in serum enzyme activities. It is concluded that marked metabolic adaptation to inhaled styrene takes place. Serum enzyme determinations may prove valuable in the adaptation period whereas they may not reflect beginning chronically neurotoxic effects.

Myelin composition in acute and chronic multiple sclerosis in relation to cerebral lysosomal activity

The neuropathology of 3 cases of acute multiple sclerosis was correlated with biochemical analyses. Astrocytosis was a characteristic feature of the diffuse demyelinating lesions in one case and lymphocytic cuffing characterized the well-defined plaques present in the white matter of the other two cases. No abnormalities were found in the protein or lipid composition of isolated myelin, despite a wide range of recovery. Nevertheless, the gel electrophoretic protein pattern of white matter adjacent to plaque areas showed selective loss of myelin basic protein. Lysosomal acid proteinase and β-glucuronidase levels were very significantly increased in all white matter samples in which astrocytosis was a major neuropathological feature. Levels were less markedly raised in samples containing discrete active plaques. Enzyme changes were also found in the apparently normal white matter of 2 of the cases. Acid proteinase activity was in the normal range but the activities of β-glucuronidase and acetylcholine esterase were elevated. The significance of these results in relation to glial cell activity in the early stages of demyelination is discussed.

Differentiation of a cell line of mouse myeloid leukemia: I. Simultaneous induction of lysosomal enzyme activities and phagocytosis

Induction of phagocytic activity in the Ml cell line of mouse myeloid leukemia, on being exposed to a conditioned medium from cultured embryo cells, was accompanied by an increment in the activities of both lysosomal acid phosphatase and acid protease. The activity of these lysosomal enzymes, as well as that of phagocytosis, was not induced when Ml cells were incubated either with the conditioned medium subjected to heat treatment or in the presence of 5-bromodeoxyuridine (BUdR). The levels of these induced enzyme activities in Ml cells were comparable to those in normal mouse peritoneal macrophages. The lysosomal enzyme activity in Mm-1 cells, which were spontaneously differentiated from Ml cells and exhibiting a higher phagocytic activity, were reminiscent of those in peritoneal macrophages. Based on these observations, it was concluded that both phagocytosis and lysosomal enzyme activity occur simultaneously during the course of differentiation. This differentiation, morphological or functional, in Ml cells in the presence of the conditioned medium was further supported by biochemical evidence.

Changes in cerebral lysosomal enzyme activity and lipids in multiple sclerosis

In most cases of multiple sclerosis no change was seen in the lipid composition of apparently normal white matter. Where there was depletion of lipid, chemical and enzymatic evidence of demyelination was found. Raised lysosomal enzyme activity was normally restricted to plaques but in acute cases of multiple sclerosis changes were more extensive. Even in apparently normal areas of white matter cholesterol esters were found and lysosomal acid proteinase, β-glucuronidase and arylsulphatase activities were significantly increased. The significance of these observations to the pathology of multiple sclerosis is discussed.

The protective effect of a sunscreen upon the lysosomes of ultraviolet-irradiated skin.

It has been generally accepted in the literature that the substituted benzophenones, having wide-spectrum ultraviolet absorbing properties, provide excellent protection from the harmful effects of sunburn. Evidence is here presented which indicates that release of lysosomal acid phosphatase and acid protease was facilitated in cultured human foreskin and rodent skin in vivo after exposure to UV radiation, without protection by 10% sulisobenzone. Under these experimental conditions, there occurred in human foreskin an accelerated leakage of acid phosphatase from membrane-bound sites evidenced by diffuse histochemical staining.

Release of lysosomal protease by ultraviolet irradiation and inhibition by hydrocortisone

It is well established that cathepsin D as a major lysosomal acid protease plays an important role in the catabolism of protein in various ocular tissues. In the retinal pigment epithelium (RPE), cathepsin D is involved in the degradation of shed discs during the renewal process. To date, the immunohistochemical localization and distribution of cathepsin D in human ocular tissue has not been precisely analyzed. In this study, the cellular localization of cathepsin D immunoreactivity was examined at the light microscopic level in healthy donor eyes using the alkaline phosphatase-antialkaline phosphatase (APAAP) technique. Cathepsin D immunoreactivity was found in the cellular cytoplasm of the following human ocular tissues: retinal pigment epithelium; Müller cells; ganglion cells; pigmented and unpigmented epithelium of the ciliary body; iris tissue; epithelium and endothelium of the cornea and lens epithelium. In addition, cathepsin D reaction product was detected in the glial cells of the optic nerve and in the cytoplasm of the capillary endothelium. The localization and distribution of cathepsin D and its possible role among the various ocular tissues are discussed in connection with the underlying physiological and pathophysiological conditions.