Effect of cortisol on the synthesis of chondroitin sulphate by embryonic cartilage

Polysaccharide Chemistry in Drug Delivery, Endocrinology, and Vaccines

Polysaccharides, due to their outstanding properties, have attracted the attention of researchers, working in the biomedical field and especially of those working in drug delivery. Modified/functionalized polysaccharides further increase the importance for various applications. Delivery of therapeutics for diverse ailments in different endocrine glands and hormones safely, is a focal point of researchers working in the field. Among the routes followed, the transdermal route is preferred due to non-exposure of active moieties to the harsh gastric environment and first-pass metabolism. This review starts with the overview of polysaccharides used for the delivery of various therapeutic agents. Advantages of polysaccharides used in the transdermal route are addressed in detail. Types of polysaccharides will be elaborated through examples, and in this context, special emphasis will be on the polysaccharides being used for synthesis of the membranes/films. Techniques employed for their modification to design novel carriers for therapeutics delivery will also be discussed. The review will end with a brief discussion on recent developments and future perspectives for delivery of therapeutic agents, and vaccine development.

Zonal analysis of cytoplasmic steroid hormone receptor levels: replication and synthetic activity in embryonic calf growth cartilage

Using the dextran charcoal method, a specific steroid receptor for dexamethasone, but not 17 beta-estradiol or 17 alpha-methyltrienolone, was demonstrated in cytosol prepared from mid-gestation fetal calf growth cartilage. Zonal analysis of cytoplasmic receptor levels showed that tissue sections from the center, the peripheral surface, and the palisade section bound 229 +/- 111, 173 +/- 64, and 15 +/- 28 femtomole dexamethasone per mg of protein, respectively. Incorporation of 3H-thymidine, 35S-sulfate, and 3H-proline into cartilaginous tissues was used as an index of replication and synthetic activity. The percentage of 3H-thymidine labeled nuclei, as determined by radioautography, showed that the palisade zone has a significantly lower replicating activity (P less than 0.001). Values were 5.6 +/- 1.2, 5.4 +/- 1.2, 3.8 +/- 1.3, and 1.1 +/- 0.2 for the center, peripheral surface, and upper and lower half of the palisade section. The rate of sulfate and proline incorporation into the palisade zone was over seven times higher than the central and peripheral surface (P less than 0.001). The difference in the rate of matrix synthesis and proliferating activity in these regions may be related to the zonal heterogeneity of receptor levels of glucocorticoids in fetal growth cartilage.

The effect of cortisol on porcine articular tissues in organ culture

(1) The effects of hydrocortisone succinate (1.0--0.01 micrograms HC/ml of medium) on porcine articular tissues in organ culture have been studied by histological and biochemical methods. (2) 1.0 and 0.1 micrograms HC/ml considerably inhibited the severe breakdown of matrix that occurs in living and dead cartilage explained in contact with synovial tissue. (3) The depletion of matrix in living cartilage cultivated in the same dish as but not in contact with synovial tissue, is much diminished when the medium contains 1.0 or 0.1 micrograms HC/ml. (4) Cartilage grown in the used medium of synovial tissue loses both proteoglycan and hydroxyproline; the addition of HC to the used medium has little (1.0 microgram HC/ml) or 0.1 microgram HC/ml) no inhibitory effect. If, however, the used medium is from synovial tissue that has been cultured in the presence of 1.0 or 0.1 micrograms HC/ml, loss of proteoglycan and collagen from the cartilage is much reduced. (5) In isolated cartilage in normal medium there is outgrowth of cells from the cut surface and some loss of proteoglycan and collagen; outgrowth is completely, and loss of matrix components partially suppressed by 1.0 micrograms HC/ml. (6) Isolated synovial tissue cultured in normal medium shrinks to about one-third of its original size, loses much of its collagen and secretes neutral metallo-proteinases into the medium; in the presence of 1.0 microgram HC/ml these changes are largely prevented. The explants also secrete an inhibitor of metallo-proteinases the production of which is not reduced by HC.

Regional differences in the effects of glucocorticoids on maturation of the fetal skeleton of the rat

The effects of glucocorticoids on fetal growth and development in the rat were investigated. Pregnant rats were injected subcutaneously on gestational days 12 and 13 with betamethasone (0.18 or 0.42 mg), with dexamethasone (0.12 or 0.24 mg), or with physiological saline. Fetuses at day 21 of gestation were weighed, cleared, and stained for calcification with Alizarin Red S. Fetal weight was significantly reduced at both dose levels of each steroid; a greater reduction occurred with the higher dose. Retardation of growth and of calcification of bones in the axial skeleton occurred at both doses; there was greater retardation with the high dose. In the appendicular skeleton there was enhanced calcification of some bones with the low dose, and a retardation of calcification with the high dose of each steroid. The present findings show that different regions of the fetal skeleton may respond discordantly to the effect of glucocorticoids depending on the dose.

Cortisone induced alterations of costal cartilage in single and in parabiosed rats

Cortisone-treated Buffalo rats have been parabiosed with untreated controls of the same age. The optical and electron microscopy, including histochemistry, of costal cartilage of these rats has been compared with that in single cortisone treated rats, single controls, and control parabiosed with control rats, at 14 and 28 days after parabiosis. Single cortisone-treated rats, in comparison to controls, have shown the greatest alteration in cellular morphology and in the extracellular matrix both at 14 and at 28 days. Cortisone-treated parabiosed rats demonstrate a gradation of these alterations. Cellular alterations include enhancement of lipid and glycogen deposition concrurently with the presence of numerous large cytoplasmic vacuoles containing beaded irregularly-shaped filaments, banded or unbanded collagen-like fibrils, and/or electron dense lamellar bodies. In the extracellular matrix, matrix vesicles, amianthoid fibers, randomly oriented unbanded fibrillar materials, and filament-like materials are most prominent in the single cortisone-treated rats and they are progressively less prominent in the cortisone-treated parabiosed rats, and in the parabiosed and single controls. Calcification of the extracellular matrix follows a similar pattern and is observed initially in pericellular halos of the single cortisone and in cortisone-treated rats parabiosed with controls. Histochemical techniques have shown that chondroitin sulfate is less demonstrable in the single cortisone and in the cortisone-treated parabiosed rats than it is in the single or parabiosed controls at 14 days but, at 28 days, all untreated or treated rats, single or parabiosed are basically comparable. Glycoproteins are prominent in the single cortisone-treated rats both at 14 and at 28 days and, at these same times, they are progressively less prominent in the cortisone-treated parabiosed rats and in the single or parabiosed controls. Many of the cortisone induced alterations in costal cartilage are suggestive of enhancement of the aging process.

The degradation of articular collagen by neutrophil proteinases

The action of the serine proteinase (EC 3.4.21--)of human neutrophil leucocytes, elastase and cathepsin G, on cartilage and tendon was investigated. With cartilage, both enzymes first degraded the proteoglycan, then solubilized collagen by an attack on the terminal peptides, destroying the inter- and intramolecular cross-links. There was little degradation of the helical region of the type II collagen. Elastase also solubilized type I collagen from tendon, though this was less susceptible than cartilage collagen, and attacked the terminal peptides and perhaps the helical region of type I skin collagen in solution. Cathepsin G had little or no effect on type I collagen of skin or tendon. Since massive infiltration of joint tissues by neutrophil leucocytes is a prominent feature of inflammatory joint disease, it may well be that elastase and cathepsin G make a significant contribution to the tissue damage that occurs.

The effects of exogenous cortisone acetate on development (especially skeletal development) and on circulating levels of corticosteroids in chick embryos

Chick embryos were treated with cortisone acetate on day 8 of incubation and the subsequent growth of the whole embryo and the development of the tibia studied to day 18 of incubation. Cortisone, at 10 ng to 2 mg/embryo decreased general body growth; above 0.5 mg/embryo it also retarded morphogenesis by as much as 3 Hamilton-Hamburger stages; and above 1 mg/embryo gross abnormalities were produced. The growth and differentiation of the tibia were affected to a greater extent than was the whole body. The reductions in tibial and total body weight were not linearly related to dose of cortisone injected. The exogenous cortisone acetate resulted in drastic alterations in the circulating levels of cortisone, cortisol, corticosterone, and progesterone, but plasma progesterone level was most readily correlated with the growth retardation. This study emphasizes that avian embryos can readily compensate for exogenous corticosteroids and that caution must be exercised when attributing causality to the substance administered.

Cathepsin D. Characteristics of immunoinhibition and the confirmation of a role in cartilage breakdown

1. Antisera were raised against lysosomal cathepsin D of man, chicken and rabbit. 2. The antisera were found to be specific and potent inhibitors of cathepsin D activity. 3. The immunological nature of the inhibition was established. 4. The inhibitory effect was studied by varying pH, antiserum/enzyme ratio, time of incubation, concentration of components and order of mixing, and by using purified antibody and univalent antibody fragments. 5. The specificities of the antisera were examined with respect to other enzymes, isoenzymes of cathepsin D and cathepsin D from different organs. 6. The antisera prevented the action of cathepsin D on isolated proteoglycans and on cartilage. 7. The antisera produced up to 90% inhibition of the autolysis of cartilage from chicks and rabbits, indicating that cathepsin D is the enzyme mainly responsible for the breakdown of proteoglycans in this system.