Myeloperoxidase (MPO) purified from human neutrophils was endocytosed by human monocyte-derived macrophages with a K of uptake of 10.6nM and a Kd of 27.8nM. Fucoidan and mannan inhibited the uptake of MPO into the macrophages, indicating that the uptake was mediated by mannose/fucose receptors. Internalized MPO was degraded with a half time of 5.5h, and the degradation was inhibited by chloroquin. The presence of cytokines during the differentiation of monocytes into macrophages caused enhancement of the endocytosis of MPO by macrophage-colony stimulating factor (M-CSF), granulocyte macrophage-colony stimulating factor (GM-CSF), interferon-γ (IFN-γ), interleukin-5 (IL-5), and transforming growth factor-β (TGF-β), and inhibition of it by interferon-α (IFN-α). The stimulatory effect of IFN-γ or GM-CSF was antagonized by IFN-α, but that of TGF-β was not. In differentiated macrophages, the endocytosis was stimulated by IFN-α and TGF-β, while it was inhibited by IFN-γ. Expression of the receptor seems to be under multistep control during macrophage differentiation.
To elucidate further the mechanism of lipid hydroperoxide (LHP) induced neovascularization, we determined the effect of linoleic acid hydroperoxide (18:2-OOH) on bovine aortic endothelial cells (BAEC) in terms of cell proliferation, migration, and tube formation. The influence of some antioxidants on these systems were also investigated. The concentration of basic fibroblast growth factor (bFGF) in the culture medium was determined by an immunoassay. Exposure to 10-7M 18:2-OOH increased BAEC proliferation, migration, and tube formation by 117, 167, and 181%, respectively, as compared with control values. The concentration of bFGF in the culture medium was increased 3 fold by 10-7M 18:2-OOH exposure for 3h, compared with that of controls (5.1 vs. 1.7pg/mg protein). BAEC migration induced by 10-7M 18:2-OOH was inhibited significantly by 10-7M bucillamine (p<0.05), which contains two sulfhydryl groups; by 10-7M troglitazone (p<0.05), which structurally similar to α-tocopherol; and by 10-7M EPC-K1 (p<0.01), an α-tocopherol and ascorbic acid conjugate. Antioxidants showed marginal effects on proliferation. The de novo synthesis of bFGF after the 18:2-OOH stimulus for 3h was reduced from 5.1pg/mg protein to 2.0pg/mg protein by treatment with bucillamine. These results suggest that 18:2-OOH induced BAEC growth is partly related to bFGF release, or synthesis.
To determine the abnormal glycosylation patterns of IgG in patients with rheumatoid arthritis (RA), we analyzed these oligosaccharide profiles using a recently established high-performance liquid chromatography (HPLC) method. Oligosaccharides of IgG proteins purified from sera of RA patients were labeled with a fluorescent reagent, 2-aminopyridine. The oligosaccharide derivatives were separated into 12 peaks by HPLC, and compared with those of age-matched controls. Serum IgG from patients with RA (RA-IgG) contained a higher content of oligosaccharides with bisecting GlcNAc than normal IgG, which was accompanied by an increase in the glycosylation of the bisected oligosaccharides. The ratio of the glycosylation of bisected to nonbisected oligosaccharides correlated with RA disease activity as well as with its clinical markers. This ratio reflecting the balance of glycosylation between bisected and nonbisected oligosaccharides may be a useful clinical parameter to monitor RA activity.
Administration of pentazocine lactate (3mg/kg body weight per day) for 10 or 20 days to male rats decreased testicular weight and significantly reduced the protein, DNA, and RNA contents of the testes. Testicular lipids increased significantly after the treatment. Activities of the esterase and acid phosphatase decreased significantly after pentazocine treatment, whereas the alkaline phosphatase activity was found to be elevated. The data suggest that pentazocine analgesia interferes with biochemical components and metabolic activities of the testis, which interference results in the accumulation of lipids. This is possibly due to the suppressed steroidogenesis and spermatogenesis.
Significant alteration in the glycosaminoglycans (GAG) and glycoproteins is observed in the brain of protein calorie-malnourished rats. There was a significant decrease in the protein in the brain, and the changes in the GAG and glycoproteins may be a consequence of this decrease. The GAG in the brain showed a significant increase, and the increase in heparan sulfate is particularly significant since it can lead to increased heparan sulfate-protein complex formation and accumulation in the brain, possibly affecting brain function. The activity of many enzymes involved in the catabolism of proteoglycans was increased in the brain of malnourished rats. The fact that there was an increase in most of the glycosaminoglycans in spite of the increased activity of the catabolizing enzymes may indicate some form of resistance of the proteoglycans to degradation. On the other hand, the carbohydrate components of brain glycoproteins—total hexose, fucose, and sialic acid—decreased in the malnourished rats, whereas there was increase in the concentration of dolichol. The activity of enzymes concerned with the catabolism of glycoproteins also showed an increase. The decrease in the carbohydrate components of glycoproteins in the brain in the malnourished rats in spite of increased availability of dolichol for glycosylation, may be due to their decreased biosynthesis and glycosylation and increased catabolism. The nature of the changes in various carbohydrate components was different, indicating formation of altered glycoproteins. The altered glycoproteins in the brain in malnourished rats may affect receptor function of the neuronal cell membrane. Thus alteration in both glycosaminoglycans and glycoproteins can lead to changes in the brain function in malnutrition.
In a study carried out by us in human volunteers, we found that consumption of coconut kernel along with coconut oil produced lower serum total cholesterol, LDL cholesterol, and LDL cholesterol/HDL cholesterol ratio, when compared with consumption of coconut oil alone. The aim of this study was to find out whether this beneficial effect of coconut kernel is due to the protein present in it. Metabolism of lipoproteins was studied in rats fed coconut kernel protein (I) as compared with that in those fed casein (II). Rats fed I showed (i) decreased lipids in both HDL and LDL+VLDL, (ii) increased activity of lipoprotein lipase and plasma LCAT, and (iii) decreased synthesis and secretion of lipoproteins by hepatocytes in culture. The lipid-lowering effect of kernel protein may thus be due to decreased synthesis and secretion of lipoproteins and their increased clearance from circulation. The kernel protein may therefore be a factor responsible for the beneficial effect of the whole kernel.
The biochemical effects of L-arginine pre-treatment against isoproterenol-induced changes with respect to lipid metabolism were studied in male albino rats. The levels of cholesterol, triglycerides, and free fatty acids were estimated in both serum, and the myocardial tissue. Levels of lipid peroxides, LDL and HDL cholesterol in the serum, and total lipids and phospholipids in the myocardial tissue were also estimated in the normal and experimental rats. Isoproterenol-induced significant increases in the levels of LDL cholesterol and other lipid components in the serum and myocardial tissue (except phospholipids) were restored to near normal levels in the rats given L-arginine pre-treatment prior to the induction of myocardial stress by isoproterenol administration, thereby exhibiting a protective effect of L-arginine against isoproterenol-induced myocardial damage in rats. Results of our preliminary study thus reveal that L-arginine is cardioprotective in experimental rats.