Chondroitin sulfate uptake

Crocker sarcoma and Mecca lymphosarcoma tumors were found to accumulate the radioselenium slowly and continuously in contrast to rapid uptake and clearance of the label from most normal organs. Clinically, the affinity of tumors for selenium has been the basis for utilizing a radioactive nuclide of selenium as a tumor localizing agent (62, 64) The reason for the localization of selenium is not readily apparent but may reflect enhanced division rates, protein and chondroitin sulfate biosynthesis, or a decrease in the detoxification of selenium. An outgrowth of these observations has been to examine the in vitro effects of selenium supplementation on cellular propagation. 

The exchange of acetyl groups and the uptake of 8 04" in chondroitin-sulfate in slices of cartilage tissue have been studied. 

Then, we attempted to examine the effects of chondroitin sulfate on palmitic acid and 2-monooleoylglycerol uptake into the brush border membrane vesicles of the rat small intestine in vitro. As shown in Fig. (15), chondroitin sulfate inhibited the incorporation of palmitic acid into... 

Nuclear oxidative phosphorylation is difficult to quantify. Although oxygen uptake in the nucleus can be measured, no exact P/O ratio is available. This is because only the AMP already present in the nuclear preparation can be converted to ATP any AMP added to the nuclei remains unaltered. An intriguing observation is the effect of DNase on the phosphorylation of AMP. (Allfrey has proposed that DNase blocks ATP synthesis in the nucleus indirectly namely, by inhibition of the nuclei by the histones, which after DNA extraction are no longer associated with DNA by salt linkages [35].) The enzymic extraction of 55% of the DNA in the nucleus leads to the loss of nuclear phosphorylation properties, which can be restored by adding DNA to the system. The effect of DNA is not specific because DNA can be replaced by RNA, polyadenylic acid, heparin, chondroitin sulfate, and polyethylene sulfate. Oxidative phosphorylation in thymus nuclear preparation has been confirmed in two laboratories. Whole body doses of ionizing radiation inhibited oxidative phosphorylation in thymus nuclei. 

Chondroitin sulfate proteoglycan-LDL completes are taken up rapidly by macrophages [33, 34] and smooth muscle cells [35]. Such uptake leads to the accumulation of intracellular lipid and the formation of foam cells which are characteristically found in atherosclerotic lesions. Internalization of CSPG-LDL complexes takes place via LDL receptor dependent and independent pathways and is accompanied by decreased degradation of the internalized LDL and increased cholesterol ester synthesis. Thus, proteoglycans not only promote the extracellular retention of lipoproteins but the intracellular retention as well. 

Fetal pig epidermis contains hyaluronic acid and chondroitin 4-sulfate containing mucopolysaccharide (S15) as does human epidermis (M13), and some of the enzymes of uronic acid metabolism are present in human epidermis (F24). Also Barker et al. (B6) have shown uptake of radioactive sulfate into epidermis, and Braun-Falco et al. (B33) have shown that psoriatic epidermis is more active than normal epidermis in accumulating radioactive sulfate in vitro. There is also a suggestion that methionine sulfur may be preferentially accumulated in psoriatic lesions (B26, L6). There seems to be little doubt, therefore, that mucopolysaccharides are formed, and there is some suggestion that they may be formed in greater amounts in psoriatic skin lesions. The next section will consider the possibility that they are of importance in the cell membrane and intercellular contact. 

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