Release of lysosomal protease by ultraviolet irradiation and inhibition by hydrocortisone

Dexamethasone megadoses stabilize rat liver lysosomal membranes by non-genomic and genomic effects

PURPOSE

Membrane-stabilizing effects may be part of glucocorticoid action during high-dose glucocorticoid therapy. The present study investigates the mode of action of dexamethasone megadoses on rat liver lysosomal membranes.

METHODS

Following intravenous administration of dexamethasone in rats, the release of beta-glucuronidase from liver lysosomes was assessed ex vivo as a marker for lysosomal membrane integrity.

RESULTS

Dexamethasone megadoses significantly inhibited beta-glucuronidase release 10 min post-administration by 38% (3 mg/kg dexamethasone) and 33% (10 mg/kg dexamethasone) at corresponding dexamethasone liver concentrations of 3.9 x 10(-5) mol/kg and 15.1 x 10(-5) mol/kg, respectively. Comparable inhibition of beta-glucuronidase release (34% for 3 mg/kg and 38% for 10 mg/kg) was observed 24 h after administration of dexamethasone, although dexamethasone liver concentrations had already declined to 0.09 x 10(-5) mol/kg and 0.19 x 10(-5) mol/kg, respectively. A 2-h oral pretreatment of rats with the glucocorticoid receptor antagonist RU 486 (10 mg/kg) did not alter immediate (10 min) stabilization by dexamethasone (3 mg/kg). but almost completely prevented lysosomal membrane protection 24 h after dexamethasone injection.

CONCLUSIONS

Dexamethasone megadoses may preserve lysosomal membrane integrity by a dual action involving both rapid nongenomic effects occurring instantaneously after administration and long-term receptor-dependent genomic events.

The effect of hydrocortisone on the response of fetal rat skin in culture to ultraviolet irradiation

1. The effect of hydrocortisone on the development of fetal rat skin in organ culture, and on its repair after exposure to a mixed beam from a mercury lamp, are described. 2. The addition of hydrocortisone (7.5 µg/ml) to the culture medium (HC medium) caused accelerated differentiation and keratinisation of the epidermis followed by atrophic changes as in vivo. 3. Explants were grown for 2 days in either normal or HC medium and then irradiated with light from an Hanovia lamp. 4. Irradiation of the control explants produced severe necrosis in both epidermis and dermis and much disorganisation of the dermal intercellular material; 2 days after exposure the s. corneum with adherent cellular debris had become either completely detached from the denuded dermis, or raised to form a fluid-filled blister. Epidermal regeneration had begun by the 4th day after irradiation and was usually complete by the 6th day. 5. Hydrocortisone modified the response to irradiation as follows: (1) reduced and retarded cellular breakdown, (2) prevented vesication, (3) preserved the organisation of the dermal intercellular material, (4) hastened epithelialisation, (5) accelerated the differentiation of the new epidermis. Effects (2), (3), and (4) were probably secondary to (1). 6. Experiments with various light filters showed that the effective wavelengths for producing lesions in the skin explants were those below 3000 A. 7. It is suggested that the beneficial effect of hydrocortisone on the repair of irradiated skin explants might be due, at least in part, to a reduced proteolytic activity in the damaged tissue through a stabilising action of the hormone on the lysosomes. 8. The relationship of these findings to clinical observations is discussed.

Studies on lysosomes. I. The effects of endotoxin, endotoxin tolerance, and cortisone on the release of acid hydrolases from a granular fraction of rabbit liver

Granular fractions sedimenting between 800 g and 15,000 g have been prepared in 0.25 M sucrose from the livers of normal young rabbits and from the livers of rabbits injected with A. aerogenes endotoxin. As early as 5 minutes after endotoxin, there was an augmented release of two enzymes, beta glucuronidase and cathepsin, into the supernatant of fractions which had been incubated or incubated and irradiated with a mercury vapor lamp at 37 degrees C. These effects were maximum at 30 minutes after endotoxin and were associated with a depletion of the total activities of the two enzymes within the granules. Concurrently there was a rise in the activity of the two enzymes in fractions of the homogenate which were unsedimentable at 15,000 g. Fractions prepared from animals made tolerant to endotoxin no longer responded to incubation and irradiation by an augmented release of these two hydrolases, nor did fractions prepared from animals pretreated with glucocorticoids. Pretreatment with DOCA did not prevent release of enzymes after endotoxin. The results have been interpreted to indicate that one consequence of the injection of endotoxin is an effect upon the stability of lysosomes, with subsequent release of acid hydrolases into the cell sap or surrounding tissue. Glucocorticoids may exert their pharmacologic effects through the protection of these subcellular particles against a variety of injurious agents.

Pathogenesis of experimental shock. IV. Studies on lysosomes in normal and tolerant animals subjected to lethal trauma and endotoxemia

Fatal shock was produced in animals by drum trauma, temporary occlusion of the superior mesenteric artery, and bacterial endotoxin. Measurements were made of release of beta glucuronidase and cathepsins from the large granule fractions of livers, and of levels of circulating beta glucuronidase and acid phosphatase in these animals. Experiments were also carried out with animals rendered tolerant by previous exposure to sublethal amounts of trauma or by pretreatment with cortisone. The results show that release of beta glucuronidase and cathepsins from the large granule fraction of liver was increased during traumatic and endotoxin shock in the rat. Similarly, circulating levels of acid phosphatase and beta glucuronidase were increased during traumatic shock in rats and rabbits, and during endotoxin shock in rats. The data also indicate that tolerance to traumatic injury, induced by prior conditioning, prevented the increase in levels of circulating acid phosphatase normally observed after stress, and may have been associated with an increased stability of hepatic lysosomal particles. In addition, cortisone, which appears to "stabilize" hepatic lysosomes in vivo, also reduced the increase in plasma acid phosphatase brought about by endotoxin and trauma. From the foregoing observations, it is suggested that: (a) Disruption of lysosomes and release of their contained enzymes in free, active form may occur in liver and intestine of shocked animals. (b) The activation of lysosomal hydrolases within cells and their release into the circulation may play an important role in exacerbating tissue injury and accelerating the development of irreversibility during shock. (c) The increased stability of lysosomes of tolerant and of cortisone-treated animals may constitute an important component of the resistance of these animals to shock.

THE EFFECT OF ANTISERUM, ALONE AND WITH HYDROCORTISONE, ON FOETAL MOUSE BONES IN CULTURE

1. The effects of normal rabbit serum and of rabbit antiserum to whole foetal mouse tissues, on the isolated limb bones of late foetal mice were studied in organ culture, and the influence of hydrocortisone on these effects was investigated. 2. Unheated normal serum caused slight loss of metachromatic material from the cartilage matrix, and some resorption of both cartilage and bone. 3. In unheated antiserum to foetal mouse tissues, the terminal cartilage was smaller and less metachromatic than in paired controls in normal serum, while osteoclasis was so intense that in many explants the bone had almost disappeared. The amount of necrosis varied with different batches of antiserum. 4. The changes produced by normal serum and antiserum could be largely prevented by heating the sera to 57 degrees C for 45 minutes. 5. The effects could also be inhibited by the addition of hydrocortisone to the unheated sera; as little as 0.1 microg hydrocortisone per ml of medium had a well marked protective action. 6. It is suggested that (a) unheated antiserum causes a release of lysosomal enzymes with consequent breakdown of intercellular material, (b) this release is due to an indirect action on the lysosome via an increased permeability of the cell membrane, (c) hydrocortisone does not affect the antigen-antibody reaction, but inhibits the autolytic changes that normally follow this reaction, possibly by stabilising both the lysosomal and cell membranes.

QUANTITATIVE STUDIES ON THE BEHAVIOR OF SENSITIZED LYMPHOCYTES IN VITRO. II. INHIBITORY INFLUENCE OF THE IMMUNE SUPPRESSOR, IMURAN, ON THE DESTRUCTIVE REACTION OF SENSITIZED LYMPHOID CELLS AGAINST HOMOLOGOUS TARGET CELLS

The cytocidal effect of specifically sensitized lymphoid cells on homologous target cells in culture can be inhibited by small quantities of an imidazole derivative of 6-mercaptopurine (imuran). This inhibition takes place only in the continuous presence of this drug, and at concentrations which apparently do not affect the viability of the attacking lymphoid cells. These results seem to support the contention that RNA-dependent protein synthesis on the part of the lymphoid cells is necessary for a destructive interaction between sensitized node cells and homologous target cells in vitro.

STUDIES ON LYSOSOMES. V. THE EFFECTS OF STREPTOLYSINS AND OTHER HEMOLYTIC AGENTS ON ISOLATED LEUCOCYTE GRANULES

Granules from rabbit peritoneal leucocytes were prepared in 0.3 M sucrose as an optically homogeneous suspension with the aid of heparin. Lysis of the granules in vitro was followed by measurement of decreases in the apparent absorbance of the suspensions at 520 mmicro and was accompanied by solubilization of beta-glucuronidase from the particles. Streptolysins O and S from hemolytic streptococci lysed the granules at 20 degrees C; the initial rate of lysis by streptolysin O was greater than that by streptolysin S. Cysteine activated, and specific antibody inhibited, streptolysin O; antimycin and bovine serum albumin inhibited streptolysin S. The granules were not lysed by any other streptococcal exotoxins. Lysis was irreversible and depended neither upon oxidative phosphorylation, nor upon intact respiration. The granules were also lysed by lysolecithin, at concentrations from 2 x 10(-6)M to 1 x 10(-4)M; bovine serum albumin and antimycin also inhibited this lytic agent. Such other hemolytic agents and procedures as vitamin A, non-ionic detergents, and ultraviolet irradiation also disrupted leucocyte granules. In susceptibility to lysis and other properties, the granules of white cells resembled erythrocytes. Leucocyte granules differed from mitochondria in that they did not appear to take up or extrude water reversibly; they were unaffected by thyroxine, phosphate, or metabolic substrate. The studies are compatible with the hypotheses that white cell granules are similar to lysosomes isolated from other tissues, and that they share common surface properties with erythrocytes.

STUDIES ON LYSOSOMES. III. THE EFFECTS OF STREPTOLYSINS O AND S ON THE RELEASE OF ACID HYDROLASES FROM A GRANULAR FRACTION OF RABBIT LIVER

Streptolysins O and S from hemolytic streptococci have been added to granular fractions of tissue homogenates in 0.25 M sucrose prepared from rabbit liver, heart, spleen and lymph nodes. At concentrations ranging from 0.65 microg/ml to 2.0 mg/ml of streptolysin S, and from 10 microg/ml to 1.0 mg/ml of streptolysin O, two lysosomal enzymes (beta glucuronidase and acid phosphatase) and, to a lesser degree, one mitochondrial enzyme (malic dehydrogenase) were released into the supernatants of the reaction mixture. Although the hemolytic action of each lysin paralleled the effect on lysosomes, at equivalent levels of hemolytic activity, SLS was approximately 10 times more active on lysosomes than SLO. SLO was inhibited by cholesterol, cortisol, and specific antibody in vitro; pretreatment of animals with cortisone decreased the susceptibility of their isolated lysosomes to SLO. These agents failed to prevent SLS action on lysosomes. SLO had a pH optimum of 6.5 against lysosomes while SLS was maximally active at 7.5. No other streptococcal extracellular products were as active on lysosomes as the streptolysins, although activated streptococcal proteinase precursor released some hydrolases from the granules. Similarities between the actions of SLO and SLS on red cells and lysosomes suggested that the membranes bounding lysosomes and erythrocytes have common properties.

THE EFFECTS OF PAPAIN, VITAMIN A, AND CORTISONE ON CARTILAGE MATRIX IN VIVO

The extreme and, apparently, selective vulnerability of chondromucoprotein in cartilage matrix to the action of proteolytic enzymes in vivo provides a useful model for studying factors involved in the transport, inhibition, and activation of a protease, papain, in the blood and tissues. The lysis of cartilage matrix which occurs in hypervitaminosis A is the result of release, probably from chondrocytes, of cathepsins normally contained within lysosomes. Cortisone possesses two properties which are not only of importance for this experimental model but also may have more general bearing on the physiological functions of this hormone with respect to connective tissue. One property is to prevent the resynthesis or deposition of chondroitin sulfate in cartilage matrix, after depletion of the latter. The other, which may be relevant to the "anti-inflammatory" actions of cortisone, is to increase the stability of lysosomes and prevent release of the acid hydrolytic enzymes contained in these organelles.

Localization of lysosomal enzymes in the retina and retinal pigment epithelium of RCS rats

Using ultrahistochemical and immunohistochemical techniques, localization of acid phosphatase and cathepsin D was demonstrated in the retina and pigment epithelium of 1 to 42 day old RCS rats and its nonaffected congenic rat strain. Both enzymes are present in the pigment epithelium of the normal and dystrophic rat eye. As early as the age of 1 week, it was found that the lysosomes in the dystrophic rat retina are less stable in releasing acid phosphatase than those of control animals. Infiltration of cathepsin D into the subretinal space could first be detected with certainty in 2-week-old animals. The fragility of the lysosomal membrane and, therefore, the release of both enzymes became more pronounced as the animals aged. The findings of this study indicate that the instability of the lysosomal membrane in the RCS rat pigment epithelium may initiate degeneration of photoreceptors and pigment epithelium. The demonstration of cathepsin D activity has proved very helpful in revealing the physiological or pathophysiological condition of retinal pigment epithelium.

Cortisone extends life span in the rotifer Asplanchna brightwelli

Cortisone at 100 and 200 microM concentrations produced a significant increase in both life span and reproduction in the rotifer Asplanchna brightwelli. Two possible mechanisms are discussed to explain these results: (1) cortisone stabilization of lysosomal membranes, or (2) recognition of cortisone as a hormone capable of altering resource allocation by the rotifers.

Effect of salai guggal ex-Boswellia serrata on cellular and humoral immune responses and leucocyte migration

Effect of alcoholic extract of salai guggal (AESG) was studied on cellular and humoral immune responses in mice and leucocyte migration in rats. Oral administration of AESG strongly inhibited the antibody production and cellular responses to sheep red blood cells in mice. It inhibited the infiltration of polymorphonuclear leucocytes and reduced the volume of pleural exudate in carrageenan induced pleurisy in rats. It showed no cytotoxic effect.

Hydrocortisone administration alters glial reaction to entorhinal lesion in the rat dentate gyrus

Young adult male rats received subcutaneous implants of Alzet osmotic minipumps which delivered 400 micrograms hydrocortisone per day. Untreated rats received no pumps or pumps containing the vehicle. Five days after receiving the implantation, both groups of rats were subjected to unilateral entorhinal lesion. Seven days after surgery, brains were analyzed quantitatively for glial changes in the denervated dentate outer molecular layer. Numerical densities of astrocytes and nonastrocytic glia were calculated by cell counting using 1.0-micron toluidine blue-stained sections. Glial acid phosphatase staining was quantitated using computer-assisted cytophotometric measurement of individual glial cells. Hydrocortisone-treated animals demonstrated 31% more astrocytes and 22.4% less nonastrocytes in the dentate outer molecular layer compared with untreated animals. Glia in the treated animals also showed a 33% decrease in average optical density of cytoplasmic acid phosphatase staining. These findings suggest that hydrocortisone treatment prior to and following an entorhinal lesion accelerates lesion-induced migration of astrocytes to the outer molecular layer, and reduces the increase in microglial number resulting from the lesion. The observed effect on microglia may result from a direct hormonal inhibition of local proliferation of microglia or from the well known systemic anti-inflammatory action of glucocorticoids on monocytes, the putative precursors of brain microglia. Our findings suggest that glucocorticoid hormones significantly alter the response of non-neuronal cells to neural tissue damage.

Altered regulation of lesion-induced synaptogenesis by adrenalectomy and corticosterone in young adult rats

Quantitative electron microscopy was used to examine the effect of circulating glucocorticoids on the removal of degenerating synapses and the replacement of lost synaptic contacts in young adult rats that follow partial denervation of the hippocampal dentate gyrus. Subjects were adrenalectomized prior to subcutaneous implantation of pellets containing a specified concentration of corticosterone and subsequent unilateral ablation of the entorhinal cortex. Animals maintained at high circulating concentrations of glucocorticoids were significantly retarded in the early phase of degenerating synapse removal and in the rate of synaptic replacement. Subjects maintained at extremely low concentrations of glucocorticoids were also significantly retarded in the early stages of synapse removal but showed an early replacement of lost synaptic contacts followed by a dramatic decrease in the rate of replacement. By 60 days after the lesion both groups of animals showed synapse replacement equivalent to young adult controls while significant amounts of degenerating synapses still remained in the denervated neuropil. The results demonstrate that circulating glucocorticoids can exert a marked influence on lesion-induced synaptic replacement in the hippocampal dentate gyrus.

Influence of daunorubicin on membrane permeability properties: detection by means of intracellular accumulation and efflux of fluorescein

The influence of daunorubicin (DNR) on membrane permeability properties was assessed by studying the ability of living HeLa cells to exhibit fluorochromasia; that is, to take up a fluorogenic substrate and retain the fluorescent compound obtained by enzymatic reaction. The intracellular accumulation of the fluorescent product as well as its release by the cells may be considered indicators of the permeability properties, since both processes are mediated by the cell membrane. The influence of the drug on the accumulation and on the efflux of fluorescein, obtained intracellularly from the hydrolysis of fluorescein diacetate (FDA), was evaluated, after DNR treatment, by measuring the fluorescence intensity of the product in single living cells by flow cytometry. The results showed that DNR, up to a concentration of 5 X 10(-6) M, did not significantly affect the accumulation of fluorescein. On the contrary, the efflux was strongly inhibited. A comparative study of the influence of drugs with known action mechanism was performed with the membrane-active compound hydrocortisone (HC) and with the metabolic inhibitor KCN. The results obtained indicate that DNR significantly affects membrane permeability properties and that its influence is similar to that exerted by metabolic inhibitors.

Glucocorticosteroids and oral medicine

The article deals with the use of glucocorticosteroids in the treatment of the oral manifestations of Systemic Lupus Erythematosus (SLE), Discoid Lupus Erythematosus (DLE), Rheumatoid Arthritis (RA) in the temporomandibular joint, Pemphigus Vulgaris, Pemphigoid, Erythema Multiforme Exudativum (EME), Lichen Planus (LP), and Recurrent Aphthous Ulcerations (RAU). The benefit from steroids is discussed on the basis of current knowledge of etiology and pathogenesis of the various disorders. All of them are characterized by inflammation which appears secondary to a hypersensitivity reaction against autocomponents. Glucocorticoids do not interfere with the primary disease mechanisms. But it is concluded from the literature, that because of anti-inflammatory and immunosuppressive effects of the hormones, it seems reasonable to profit from steroids as palliatives in acute phases of the diseases and/or as long-term suppressors of the general host defense.

Pharmacologic inhibition of experimentally induced SLE-like deposition of immunoglobulins in skin nuclei

Binding of autologous immunoglobulins to epidermal nuclei can be induced in mice sensitized to ultraviolet-irradiated DNA following total body uv irradiation. The lesions, which resemble those observed in human systemic lupus erythematosus (SLE), are characterized histologically by the accumulation of polymorphonuclear (PMN) cells at different skin sites. In the present investigation this experimental model has been employed to study whether currently used anti-inflammatory (chloroquine, hydrocortisone, indomethacin) and polyvalent antiprotease (trasylol) drugs can either abolish or reduce the development of this murine pathology. The results of this study demonstrate that while trasylol, chloroquine, and indomethacin are able to inhibit, with variable effectiveness, the experimental skin lesions, hydrocortisone does not manifest any therapeutic activity.

Cortisol inhibition of development of various lysosomal enzymes in cultured palatal shelves from mouse embryos

The lysosomal enzymes, non-specific esterases, beta-glucuronidase, N-acetyl-beta-glucosaminidase and aryl sulphatases A and B, were examined histochemically in medial-edge epithelia (MEE) of single palatal shelves in vitro. Activities of most enzymes increased gradually in MEE with a peak at 24-26 h of culture. Aryl sulphatase B activities were lower than the others and aryl sulphatase A activities could not be detected in the palatal cells during the entire culture period. By 48 h, MEE cells degenerated and were lost. Cortisol suppressed increased activities of these hydrolytic enzymes and prevented programmed breakdown of the palatal epithelium.

Lesion-induced synaptogenesis in the dentate gyrus of aged rats: II. Demonstration of an impaired degeneration clearing response

Previously we reported that a delayed onset in the reinnervation of the outer two-thirds of the dentate molecular layer occurred in aged rats after an entorhinal lesion. Several factors associated with formation of new synaptic contacts and removal of degenerative debris may affect the reinnervation process. In this study the appearance and removal of degeneration was analyzed and evaluated with respect to the delayed reinnervation process in aged rats. After a complete lesion of the entorhinal cortex, 85-90% of the input to the outer two-thirds of the ipsilateral molecular layer is lost. Electron-dense and electron-lucent degeneration are present throughout the outer two-thirds of the denervated molecular layer. In both aged and young adult rats, the electron-lucent degeneration disappears by 10 days postlesion. The predominant electron dense degeneration, however, is removed at a different rate by young adult and aged rats. Young adults demonstrate a biphasic degeneration removal process, with almost half of this degeneration rapidly lost by 10 days postlesion, and nearly all by 60 days postlesion. Aged animals in contrast, have lost only 16% of the dense degeneration at 10 days postlesion, with about 30% of the degeneration remaining at 60 days postlesion. The impaired removal of the degeneration from the denervated zone appears to be reciprocally related to the reinnervation response in both age groups and may be related to the normal astrocyte hypertrophy and elevated corticosteroid levels in aged rats.

The efficacy of anti-inflammatory agents with respect to extracellular phospholipase A2 activity

The effects of steroidal and non-steroidal anti-inflammatory agents on extracellular phospholipase A2 (PLA2) activity were investigated. Enzyme release was inhibited by 5 x 10(-8) M dexamethasone but not by indomethacin, whereas the soluble extracellular enzyme was inactivated by mepacrine but not by dexamethasone or indomethacin. PLA2, released into the interstitium by activated macrophages is both pro-inflammatory and vasoactive. The anti-inflammatory efficacy of steroidal and non-steroidal drugs may partially reside in their ability to inhibit the release of PLA2, or inactivate preformed extracellular PLA2 in chronically inflamed sites.

Stabilization of rat liver lysosomes by new anti-inflammatory steroids in vitro

Steroid acid esters, synthesized by modifying the 17-ketol side chain of prednisolone, were tested for their in vitro ability to stabilize heavy mitochondrial lysosomes prepared from rat liver. Membrane stabilization was determined by assessing capability of steroids to decrease extrusion of the marker enzymes (acid phosphatase, beta-glucuronidase and aryl sulfatase) from lysosomes incubated in hypo-osmotic sucrose-Tris acetate buffer. Results indicated that prednisolone (1) significantly inhibited the lysosomal release of acid phosphatase as did the new anti-inflammatory steroid, methyl 20-dihydroprednisolonate. Methyl prednisolonate exhibited weak membrane stabilization capacities and 20-dihydroprednisolonic acid, a metabolic product of methyl 20-dihydroprednisolonate, showed virtually no membrane stabilization.

Cytological events in allo-stimulated lymphocytes triggered by exposure to stimulatory alloantigens. IV. The influence of prednisolone

H-2b lymphocytes were sensitized against H-2d alloantigens by mixed lymphocyte culture reaction (MLR) and incubated with H-2d target cells in the presence of prednisolone or without prednisolone (control). The interaction between lymphoid cells and target cells was stopped by fixation with glutaraldehyde. Changes in cell size, in numerical density of the end of plasmic reticulum (ER) and the Golgi apparatus (GA) as well as in areal density of the lysosomes and the mitochondria in the Golgi apparatus (GA) as well as in areal density of the lysosomes and the mitochondria in the lymphoblasts during the first four hours of interaction with target cells were measured with a Hewlett Packard digitizer. The cell size showed no significant change within the first hour of interaction with target cells, but during the second hour a minor increase in cell diameter was observed whereas the diameter of the control lymphocytes increased a great deal during the first half hour as well as from the second to the third hour. The numerical density of the ER decreased throughout the four hour observation period, whereas the control lymphocytes exhibited a decrease in the numerical density of ER within the first hour after which the density increased. During the first hour of interaction with target cells the numerical density of the GA decreased and there was no increase during the rest of the observation period, whereas in the control lymphocytes the density of GA increased from the second to the third hour of interaction with target cells. There was no lysosome formation, and no significant change in the areal density of mitochondria during the four hour observation period, whereas the density of lysosomes as well as mitochondria increased in the control lymphocytes.

Cytotoxic effects of norethindrone-4 beta,5 beta-epoxide to Walker cells in culture and to rat liver in vivo

1. Norethindrone-4 beta,5 beta-epoxide was toxic to Walker cells in culture. The concentration required to produce a 50% reduction in the increase in cell numbers 72 h after exposure (ID50) was 0.05 mM. In this assay, the parent contraceptive steroid, norethindrone, was at least four times less toxic than the epoxide. 2. Norethandrolone-4 beta,5 beta-epoxide and norethynodrel-5 beta,10 beta-epoxide were as toxic as norethindrone epoxide to the Walker cells. 3. The cytotoxicity of norethindrome epoxide was dependent on the time of exposure of the cells to this compound if excess unreacted epoxide was removed by washing the cells with cysteine. The results are consistant with norethindrone epoxide causing cell death by reacting with sulphydryl groups of cellular proteins. 4. No metabolites toxic to Walker cells could be detected when the cells were incubated with norethindrone, rat liver microsomes and a NADPH generating system. 5. Cells treated with an ID50 of norethindrone epoxide for 1 h showed marked cytoplasmic vacuolation 3 hr after exposure. This vacuolation was much less marked in cells treated with an ID50 of norethindrone or in the controls. Neither group showed any nuclear abnormalities. 6. Norethindrone epoxide when given to rats in large doses (50 mg/kg) by lateral tail vein injection also caused cytoplasmic vacuolar degeneration of the liver hepatocytes, especially in the perilobular areas 3 days after dosing. When this compound was administered at a similar dose level via the hepatic portal vein massive haemorrhagic necrosis of the liver resulted. No damage to either lungs or kidneys was evident, irrespective of the route of administration.

Effect of adjuvant arthritis on collagenase and certain lysosomal enzymes in relation to the catabolism of collagen

The activity of collagenase, cathepsin B1, cathepsin D and Hyaluronidase was determined in skin, bone, liver, kidney, spleen and serum of adjuvant induced arthritic rats during the acute and chronic phase of the disease. Collagenase was assayed directly in tissue extract by a solution method using radioactive labelled substrate. The activity of collagenase, cathepsin B1 and D was found to increase significantly at both phases of the disease. The activity of hyaluronidase decreased significantly in liver, kidney and spleen of arthritic rats, while in skin, bone and serum no significant change was observed. The results are discussed with respect to catabolism of collagen in adjuvant induced arthritis. Prednisolone and L-thyroxine were administered to arthritic rats and the activity of collagenase, cathepsin B1, cathepsin D and hyaluronidase was determined in the treated groups during the acute and chronic phase of the disease. Prednisolone was found to suppress the development of arthritis which, in turn, decreased the increased activity of collagenase and lysosomal enzymes cathepsin B1 and D in tissues and serum of arthritic rats. L-Thyroxine was found to slowly diminish the development of inflammation and its beneficial action was found in mesenchymal tissues and skin of arthritic rats but not in bone.

Ultraviolet induced lysosome activity in corneal epithelium

A 5,000 W Xe-Hg high pressure lamp and a double monochromator were used to produce a 3.3 nm half-bandpass ultraviolet radiation at 295 nm. Pigmented rabbit eyes were irradiated with radiant exposures from 140 Jm-2 to 10,000 Jm-2 and evaluated by slit-lamp biomicroscopy, light and electron microscopy. Corneal threshold (Hc) was 200 Jm-2 and lens threshold (HL) was 7,500 Jm-2. The most repeatable and reliable corneal response to these levels of UV was the development of corneal epithelial granules. Histological changes included a loss of superficial epithelial cells and selective UV induced autolysis of the wing cells. It is suggested that the biomicroscopically observed granules are the clinical manifestation of the secondary lysosomes revealed by light and electron microscopy. It is proposed that UV breaks down the primary lysosome membranes to release hydrolytic enzymes which in turn form the secondary lysosomes during autolysis. Extreme levels of radiant exposure at 295 nm result in indiscriminate destruction of all layers of the corneal epithelium, but the posterior cornea was spared.

The antinflammatory effects of glucocorticosteroids. A brief review of the literature

The effects of glucocorticosteroids on immune and inflammatory responses are reviewed. The steroids seem to change the number or function of cell receptors for regulating agents, so that in areas of inflammation: (a) blood vessels dilate less, (b) lymphocytes proliferate less, (c) all leukocytes infiltrate less, (d) macrophages become less activated (digesting and secreting less), and (e) fibroblasts produce less collagen and ground substance. In addition, the corticosteroids seem to alter the response of cells to various signals from their receptors by affecting the prostaglandin system, cyclic nucleotides, and perhaps other internal mediators.

Effect of mithramycin on bone beta-glucuronidase and resorption

Mithramycin suppresses bone resorption. Its effect on the synthesis and release of beta-glucuronidase (a referent for lysosomal enzymes) in mouse calvarial explants was studied in an in vitro culture system. A newly described medium (designated as KT medium) was introduced in this specific study. Mithramycin initially inhibited the release of beta-glucuronidase into the medium and resulted in an ultimate accumulation of this enzyme in the bone. These results suggest that inhibition of bone resorption by mithramycin may be attributed to interference in release of lysosomal enzymes from bone cells.

Acid hydrolases in blister fluid. 4. Influence of ultraviolet radiation

Large, dose-related increases have been demonstrated in the activity of lysosomal hydrolases in the fluid of experimental suction blisters raised on skin previously irradiated with UVR-B. These increases appear after a latent period of 11--18 h, and the pattern of changes shows an extremely good correlation with the hydrolase profile of epidermis. These observations offer strong support for the concept that lysosomes participated in the sequence of events following UV irradiation, but seem to rule out the lysosome as the initial target for UVR.

Phase I studies of C. parvum given intravenously: effects of dexamethasone on its biologic and toxic properties

Three biologic effects were clearly associated with C. parvum infusions: a) granulocytosis with lymphomonocytopenia, b) increase in responsiveness to phytohemmagglutinin and c) increase of specific antibodies to C. parvum antigens. Addition of dexamethasone moderately altered the kinetics of leukocyte changes without affecting other properties. Side effects after intravenous administration of C. parvum (2.5 mg/m2) consisted primarily of chills and fever which lasted for periods of 6-24 hours. Side effects occurred in 77% of the infusions. Addition of dexamethasone (4 mg IVP) reduced significantly the frequency (only 22% of patients) and intensity (fever 102 F and chills for only 30-60 minutes) of side effects. Clearly, dexamethasone of the dosage employed did not abrogate C. parvum effects while reducing significantly its toxic properties.