Characterization of membrane-bound serine protease related to degradation of oxidatively damaged erythrocyte membrane proteins

It has been shown that erythrocyte membrane proteins become susceptible to degradation by membrane-bound serine protease activity after oxidative modification of the membranes (M. Beppu, M. Inoue, T. Ishikawa, K. Kikugawa, Biochim. Biophys. Acta 1196 (1994) 81-87). The aim of the present study was to clarify the presence of the serine protease in oxidized erythrocyte membranes and to characterize the selectivity of the enzyme to oxidized proteins. Human erythrocytes were oxidized in vitro with xanthine/xanthine oxidase/Fe(III) and oxidized membranes isolated. Proteolytic activity of the membranes toward spectrin obtained from oxidized membranes and bovine serum albumin oxidized with H2O2/horseradish peroxidase was increased by membrane oxidation, and the degradability of the substrates was increased by substrate oxidation. The proteolytic activity was inhibited by the serine protease inhibitor diisopropyl fluorophosphate (DFP). The 72 kDa and 80 kDa proteins in the membranes were labeled by [3H]DFP when detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions and subsequent fluorography. The 72 kDa protein was found to be a serine enzyme, acetylcholine esterase. The 80 kDa protein appeared to be responsible for the degradation of oxidatively damaged proteins. The 80 kDa protein was loosely bound to membranes and readily solubilized into a 0.1% NP-40 detergent solution. The presence of the same 80 kDa protease in intact erythrocyte cytosol was suggested. The increased serine protease activity in oxidized membranes can result from the increased adherence of the cytosolic 80 kDa serine protease to the membranes due to oxidation.

Involvement of proteasomes in migration and matrix metalloproteinase-9 production of oral squamous cell carcinoma

We investigated whether proteasomes were involved in the invasiveness of oral squamous cell carcinoma (SCC) cells. The migration of SCC cells through a gelatin-coated membrane was enhanced with tumor necrosis factor alpha (TNF alpha), which was strongly inhibited by a peptide aldehyde, N-acetyl-Leu-Leu-norleucinal (ALLN), but not by its structurally related compound, N-acetyl-Leu-Leu-methioninal (ALLM). Since ALLN is a more potent inhibitor against proteasomal proteolysis than ALLM, cell migration inhibited by ALLN may thus likely depend on proteasomes. The TNF alpha-induced migration through gelatin appeared to be associated with the gelatinolytic activity from the cells, since TNF alpha strongly enhanced the production of matrix metalloproteinase (MMP)-9/gelatinase B in the SCC cells, as detected by gelatin zymography. The production of MMP-9 was also inhibited by pretreatment with ALLN, but not ALLM, in a dose-dependent manner. Moreover, ALLN could block the activation and nuclear translocation of a transcription-activating factor, NF-kappaB, which is known to regulate MMP-9 expression in TNF alpha-stimulated SCC cells. The TNF alpha-induced degradation of IkappaB alpha was also suppressed by ALLN treatment, thus implying that the molecule linking proteasome to MMP-9 production should be IkappaB alpha. We finally reconfirmed the involvement of proteasomes in the invasive behavior of oral SCC using lactacystin, a specific proteasome inhibitor, which could prevent TNF alpha from enhancing MMP-9 production, NF-kappaB activation, induction of MMP-9 mRNA and cell migration.

The carpal stretch test at the scapholunate joint

The purpose of this study was to evaluate the principle of the carpal stretch test. Eleven upper extremities from 6 fresh cadaver specimens and 40 normal wrists from 20 volunteers were used in this study. Changes in intercarpal distances (carpal interval ratio of the radioscaphoid, radiolunate, and lunocapitate joints) and step-off deformities at the scapholunate joint seen on the posteroanterior view of an x-ray film were analyzed with and without the carpal stretch test. In the cadaver wrists, the dorsal capsulotomy and radioscapholunate ligament (stage 1), the palmar half of the scapholunate interosseous ligament (stage 2), the dorsal half of the scapholunate interosseous ligament (stage 3), and the radioscaphocapitate ligament (stage 4) were sequentially sectioned. The carpal stretch test was completed in each stage. Each carpal interval ratio increased as each stage was added. Step-off deformities at the scapholunate joint were seen in 6 of 11 wrists in stage 2 and in 10 wrists in stages 3 and 4 with the carpal stretch test. In the normal wrists, neither gender nor wrist laxity (Garcia's criteria) not influenced the results of the carpal stretch test. The carpal stretch test may be helpful in identifying occult and/or dynamic scapholunate dissociation.

Effect of n-3 fatty acid supplementation on lipid peroxidation and protein aggregation in rat erythrocyte membranes

Human erythrocytes in the circulation undergo dynamic oxidative damage involving membrane lipid peroxidation and protein aggregation during aging. The present study was undertaken to determine the effect of n-3 fatty acid supplementation on lipid peroxidation and protein aggregation in the circulation and also the in vitro susceptibility of rat erythrocyte membranes to oxidative damage. Wistar male rats were fed a diet containing n-6 fatty acid-rich safflower oil or n-3 fatty acid-rich fish oil with an equal amount of vitamin E for 6 wk. n-3 Fatty acid content in erythrocyte membranes of rats fed fish oil was significantly higher than that of rats fed safflower oil. The degree of membrane lipid peroxidation and protein aggregation of rats fed fish oil was not significantly higher than that of rats fed safflower oil when the amounts of phospholipid hydroperoxides, thiobarbituric acid-reactive substances, and detergent-insoluble protein aggregates were measured. When isolated erythrocytes were oxidized under aerobic conditions in the presence of Fe(III), the degree of membrane lipid peroxidation of erythrocytes from rats fed fish oil was increased to a greater extent than that of rats fed safflower oil, whereas the degree of membrane protein aggregation of both groups was increased in a similar extent. Hence, n-3 fatty acid supplementation did not affect lipid peroxidation and protein aggregation in membranes of circulating rat erythrocytes, and the supplementation increased the susceptibility of isolated erythrocytes to lipid peroxidation, but not to protein aggregation, under the aerobic conditions. If a sufficient amount of vitamin E is supplied, n-3 fatty acid supplementation may give no undesirable oxidative effects on rat erythrocytes in the circulation.

[CDDP-resistant early recurrent uterine cervical cancer successfully treated with low-dose oral etoposide: a case report]

A 36-year-old woman with early recurrence of uterine cervical cancer had received radiotherapy and a CDDP-containing chemotherapy regimen. She was treated with oral etoposide by administration of 50 mg/day for 21 consecutive days at 14-day intervals. After two courses, complete remission was demonstrated by disappearance of the cervical tumor mass and pelvic lymph node enlargement on MRI. Leukopenia (grade 3) occurred after five courses, as well as alopecia (grade 2) and gastrointestinal discomfort (grade 1) after two courses. The patient has shown no sign of recurrence for 1.5 years. This method might be quite effective for patients with recurrent cervical cancer as well as allowing outpatient treatment and improving the quality of life.

Effect of vitamin E on contact sensitization responses induced by 2,4-dinitrochlorobenzene in mice

The effect of vitamin E on the contact sensitization responses induced in mice by 2,4-dinitrochlorobenzene (DNCB) was studied. Mice were fed a vitamin E-adequate or a vitamin E-deficient diet for 5 weeks. The amounts of thiobarbituric acid-reactive substances in the spleens and draining auricular lymph nodes of mice were decreased by dietary vitamin E. Dietary vitamin E prevented lipid peroxidation in the spleens and lymph nodes of mice. Contact sensitization develops in two phases, induction (sensitization) and elicitation. Following sensitization to DNCB on ears, draining lymph node responses, i.e., lymph node weight, total lymph node cell number and in vitro lymph node cell proliferation as assessed by [3H]methyl thymidine incorporation, were examined. These responses, activated by DNCB, were lower in the mice fed a vitamin E-deficient diet as compared with those of the mice fed a vitamin E-adequate diet. In the elicitation phase, lymphocytes from sensitized mice respond to the antigen and blastogenate in vitro. The blastogenesis of spleen lymphocytes in the DNCB-sensitized mice was decreased by vitamin E deficiency, which was enhanced by exogenously adding vitamin E. It was found that vitamin E deficiency decreases the contact sensitization responses to DNCB in mice, but responses were restored by exogenous vitamin E. In conclusion, vitamin E may participate in the lymphocyte responses to contact allergens through scavenging reactive oxygen species.

[Case report of a recurrent nephrotic syndrome patient with sudden onset of blindness during treatment with cyclosporin A]

We report a case of recurrent nephrotic syndrome with transient blindness after taking cyclosporin A (CsA). Renal biopsy showed minimal change of nephrotic syndrome and the patient was treated with predonisolone (PSL) and cyclophosphamide leading to remission of nephrosis. CsA was given to the patient. Because of recurrence of nephrotic syndrome after tapering off PSL to 5 mg a day, 12 days after taking CsA, the patient complained of sudden onset of left eye blindness lasting for 30 minutes. When the patient visited our hospital, the disturbed vision had recovered already and there were no abnormal neurological findings, such as tremors and seizures. Funduscopic examination revealed no evidence of abnormalities and brain computerized axial tomography was unremarkable. From these findings, we predicted that constriction of an artery and temporarily formed thromboembolization in an eyeground artery had caused the sudden vision disturbance. Even though there is a high incidence of thrombotic complications in cases of nephrotic syndrome, we believe that vascular constriction and formation of thrombi in the eyeground artery of the case were mediated by the pathogistic effects of CsA. Because actions in association with CsA may produce constriction of small arteries, there by decreasing blood flow, initiating coagulopathy and causing endothelial cell damage, all these effects may lead to the formation of thrombo-embolic complications. In addition, when using CsA for the treatment of nephrotic syndrome, anti-platelets and/or anti-coagulant medicines should be concomitantly prescribed to avoid the thrombo-embolic complications.

TCR alpha beta+ CD4- CD8- T cells differentiate extrathymically in an lck-independent manner and participate in early response against Listeria monocytogenes infection through interferon-gamma production

T-cell receptor (TCR) alpha beta+ CD4- CD8- (double-negative; DN) T cells appear in the peritoneal cavity at an early stage of intraperitoneal (i.p.) infection with the intracellular pathogen Listeria monocytogenes. In the present report, we analysed the developmental pathway and functions of the TCR alpha beta+ DN T cells using the L. monocytogenes infection system. The TCR alpha beta+ DN T cells appeared in the peritoneal cavity after L. monocytogenes i.p. infection in adult-thymectomized lethally irradiated bone marrow chimeras and p56lck-deficient mice. The results demonstrated that the TCR alpha beta+ DN T cells can develop extrathymically in a p56lck-independent manner. Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that the TCR alpha beta+ DN T cells expressed genes for interferon-gamma (IFN-gamma), the macrophage chemotactic factors MCP-1 and Eta-1, and granulocyte-macrophage colony-stimulating factor (GM-CSF) but lacked expression of genes for interleukin-2 (IL-2), IL-4 and IL-10. As expected from the RT-PCR analysis, the TCR alpha beta+ DN T cells produced IFN-gamma in response to anti-TCR beta monoclonal antibody (mAb), anti-CD3 mAb and L. monocytogenes-infected macrophages but IL-4 was undetectable after the stimulation. Furthermore, the intracellular cytokine staining analysis demonstrated that approximately half of the TCR alpha beta+ DN T cells detectable at the early stage of L. monocytogenes infection were IFN-gamma-producing cells. All of the results suggest that the TCR alpha beta+ DN T cells develop through a unique extrathymic p56lck-independent pathway and participate in early protection against bacterial infection through activation and accumulation of macrophages.

Separation of multiple yellow fluorescent lipofuscin components in rat kidney and their characterization

Yellow fluorescent lipofuscin deposited in rat kidney was extracted in an aqueous solution and characterized after separation. Centrifugal fractionation of the extract revealed that most of the yellow fluorescence was detected in the 105,000 x g-supernatant, and little in nuclei, cell debris, mitochondria, lysosomes, microsomes and plasma membrane. The yellow fluorescence in the supernatant was fractionated by gel filtration through Sephadex columns into 5 yellow fluorescent fractions A, B (B1, B2 and B3) and C showing the same fluorescence spectra with excitation maximum/emission maximum at 400/620 nm. The components in fraction A were converted into the smaller molecular-weight components in fraction B on treatment with 4 M urea or protease, suggesting that they were proteinaceous. The smallest molecular-weight fluorescent components in fraction C were adherent to solid cellulose materials. The fluorescent components in all the fractions were soluble in water and insoluble in chloroform-methanol, indicating that they were not lipidic materials. The fluorophores in these fractions were kept stable on borohydride treatment, but readily converted into non-fluorescent components on heavy-metal ion treatment. The characteristics of the yellow fluorescence in these fractions were quite different from those of bluish lipofuscin-like fluorophores that may be generated in tissues during lipid peroxidation.

Oxidatively damaged erythrocytes are recognized by membrane proteins of macrophages

Human erythrocytes incubated with an iron catalyst ADP-chelated Fe3+ undergo oxidative damage of the membrane including lipid peroxidation, protein oxidation, and protein aggregation, and become susceptible to recognition by human macrophages. In order to clarify the membrane components of macrophages responsible for the recognition of the oxidized erythrocytes, binding of the oxidized cells to dot and Western blots of solubilized membrane of macrophages was investigated. The oxidized erythrocytes but not unoxidized cells bound to the dot blots. The binding was effectively inhibited by saccharide chains of band 3, a major glycoprotein of human erythrocytes, and lowered when the saccharide chains of band 3 were removed from the cell surface by pretreatment of the cells with endo-beta-galactosidase which specifically cleaves the polylactosaminyl saccharide chains of band 3. The oxidized erythrocytes bound to the membrane proteins of macrophages with molecular mass of about 50, 80, and 120 kDa on Western blots depending on the saccharide chains of band 3 on their surface. The results suggest that the oxidatively damaged erythrocytes are specifically recognized by these proteins of macrophage membrane having saccharide binding ability.

Induction of band 3 aggregation in erythrocytes results in anti-band 3 autoantibody binding to the carbohydrate epitopes of band 3

Involvement of band 3 aggregation in the mechanism of anti-band 3 autoantibody binding to the cell surface carbohydrate epitopes of band 3 was investigated. When erythrocytes were treated nonoxidatively with a known protein-aggregating agent acridine orange, protein aggregates of the cell membrane which are insoluble in a nonionic detergent C12E8 solution were remarkably increased. Analysis of the protein aggregates by SDS-PAGE indicated that they were composed of several species of noncovalently associated membrane proteins including band 3. 125I-labeled anti-band 3 bound to the acridine orange-treated cells, and the binding increased depending on the concentrations of acridine orange used. The binding was inhibited by band 3 and its oligosaccharides but not by the oligosaccharides pretreated with endo-beta-galactosidase, an enzyme specifically cleaves poly-N-acetyllactosaminyl saccharide chains of band 3. When erythrocytes were pretreated with endo-beta-galactosidase to remove poly-N-acetyllactosaminyl saccharide chains from cell surface prior to acridine orange treatment, the cells did not become susceptible to anti-band 3 binding. The results indicate that induction of band 3 aggregation in erythrocyte membrane leads to anti-band 3 binding to the poly-N-acetyllactosaminyl saccharide chains of band 3. Consistently, membrane proteins including band 3 were found to be aggregated when erythrocytes were oxidized with ADP-chelated Fe3+ under the conditions that induce anti-band 3 binding to the cells. Similar band 3 aggregation was observed on senescent erythrocytes whose carbohydrate epitopes of band 3 had been occupied with anti band 3. These results indicate that anti-band 3 binds to the carbohydrate epitopes of band 3 on erythrocytes when band 3 is aggregated by oxidative and nonoxidative mechanisms.

Characterization of lactoferrin-binding proteins of human macrophage membrane: multiple species of lactoferrin-binding proteins with polylactosamine-binding ability

Human lactoferrin (LF) specifically binds to human monocytic leukemia cell line THP-1 cells differentiated into macrophages, and it has been suggested that the poly-N-acetyllactosaminyl saccharide chains of LF are involved. We partially purified and characterized LF-binding proteins with affinity for polylactosamines from THP-1 cells. LF-binding activity was solubilized by nonionic detergent Triton X-100 from THP-1 cell membrane, and subjected to affinity chromatography using an LF-Sepharose column. LF-binding activity, detected by ligand blotting assay, was eluted and further fractionated by affinity chromatography using a Sepharose column coupled with band 3, a polylactosaminyl chain-containing glycoprotein of human erythrocyte membrane. LF-binding activity was separated into three fractions (frs. B1, B2, and B3). These fractions exhibited band 3-binding activity as detected by ligand blotting assay. Dodecylsulfate-polyacrylamide gel electrophoresis of frs. B1, B2, and B3, followed by detection of LF-binding activity on Western blots, indicated that frs. B1, B2, and B3 contained LF-binding proteins with a molecular mass of 35, 50 and 80, and 35-37 kDa, respectively. Binding of LF to each of the fractions on the dot blots was partially inhibited by LF oligosaccharides, band 3 oligosaccharides and lacto-N-neotetraose, each containing di-N-acetyllactosaminyl or analogous structure, Gal beta 1-->4GlcNAc beta 1-->3Gal beta 1-->4GlcNAc (or Glc). These results suggest that the 35, 50 and/or 80, and 35-37 kDa proteins on THP-1 cells are LF-binding proteins with polylactosamine-binding ability.

Poly-N-acetyllactosaminyl saccharide chains of band 3 as determinants for anti-band 3 autoantibody binding to senescent and oxidized erythrocytes

Natural IgG antibodies to band 3 glycoprotein of erythrocyte membrane (anti-band 3 IgG) are known to bind to senescent erythrocytes, and believed to initiate antibody-dependent phagocytic removal of the senescent cells from blood circulation. Anti-band 3 antibodies also bind to the erythrocytes with hereditary hemoglobin abnormalities such as sickle, beta-thalassemic and hemoglobin Köln erythrocytes. Oxidative stress appears to be responsible for the generation of senescent cell antigen on erythrocytes, to which anti-band 3 antibodies bind, since erythrocytes oxidized in vitro bind anti-band 3 IgG, and various oxidative modifications are observed in senescent erythrocytes as well as the erythrocytes with abnormal hemoglobin. Major antigenic sites of band 3 for anti-band 3 IgG autoantibodies are its sialylated poly-N-acetyllactosaminyl saccharide chains. The poly-N-acetyllactosaminyl saccharide chains on senescent erythrocytes are indeed involved in the antigenic sites on senescent erythrocytes. The finding of the carbohydrate epitopes and possible involvement of oxidative mechanism are compatible with the band 3 clustering hypothesis, in which clustering of band 3 molecules in erythrocyte membrane is supposed to be responsible for effective binding of anti-band 3 IgG to the cell surface, because the carbohydrate epitopes of band 3 can form multivalent epitopes on cell surface when band 3 molecules cluster, and oxidative stress can induce such clusters. Interestingly, poly-N-acetyllactosaminyl chains of band 3 on oxidized erythrocytes are also recognized by macrophages directly. Thus, poly-N-acetyllactosaminyl chains may play dual roles as determinants for recognition by anti-band 3 IgG and by macrophages.

Binding of anti-band 3 autoantibody to sialylated poly-N-acetyllactosaminyl sugar chains of band 3 glycoprotein on polyvinylidene difluoride membrane and sepharose gel: further evidence for anti-band 3 autoantibody binding to the sugar chains of oxidized and senescent erythrocytes

Binding specifically of naturally occurring anti-band 3 IgG antibody isolated from human plasma was investigated in a cell-free binding system. 125I-labeled human anti-band 3 IgG specifically bound to band 3 glycoprotein and lactoferrin, a glycoprotein that has poly-N-acetyllactosamine-type sugar chains like band 3, on the polyvinylidene difluoride blotting membrane. Binding was decreased by 50-70% when band 3 and lactoferrin were pretreated with N-glycosidase F, endo-beta-galactosidase, or neuraminidase. Binding of 125I-anti-band 3 IgG to band 3-Sepharose gel was partially inhibited by band 3 oligosaccharides or lactoferrin, but was less inhibited by them after they had been treated with N-glycosidase F or endo-beta-galactosidase. A significant part of 125I-anti-band 3 IgG that bound to the band 3-Sepharose gel was released upon treatment of the gel with N-glycosidase F or endo-beta-galactosidase. IgG that binds to lactoferrin (anti-lactoferrin IgG) was isolated from normal human plasma. 125I-Anti-lactoferrin IgG bound to the band 3-Sepharose gel as effectively as to the lactoferrin-Sepharose. The antibody specifically bound to the band 3- and lactoferrin-blotted membrane depending on the poly-N-acetyllactosaminyl sugar chains of the blotted glycoproteins. The results indicate that a major part (about 70%) of anti-band 3 IgG recognizes the sialylated poly-N-acetyllactosaminyl sugar chains of band 3 and lactoferrin, and the remaining part (about 30%) of the antibody may recognize the polypeptide portion of band 3. This was supported by the observation that anti-band 3 IgG effectively bound to lactoferrin-Sepharose but 33% of the antibody did not. Anti-band 3 IgG with the carbohydrate-binding property was equally obtained whether fully denatured or barely denatured band 3 was used for isolation of anti-band 3 IgG by affinity chromatography. These results provide further evidence for our proposal that the binding sites of anti-band 3 IgG to oxidized and senescent erythrocytes reside on the locally condensed sialylated poly-N-acetyllactosaminyl sugar chains of band 3 on the cell surface.

Recognition of poly-N-acetyllactosaminyl saccharide chains on iron-oxidized erythrocytes by human monocytic leukemia cell line THP-1 differentiated into macrophages

The cells of the human monocytic leukemia cell line THP-1 differentiated into macrophages bound to human erythrocytes oxidized with adenosine 5'-diphosphate (ADP)-Fe3+ chelate (ADP/Fe3+) in the absence of serum. The binding was prevented when the cells were treated with ADP/Fe3+ in the presence of antioxidants, indicating that oxidation of the cells is responsible for the increased susceptibility to the THP-1 cell binding. Galactose, fucose, mannose and mannan partially inhibited the binding. Glycoproteins containing poly-N-acetyllactosaminyl saccharide chains such as band 3 glycoprotein isolated from human erythrocyte membrane and lactoferrin, and their oligosaccharides, strongly inhibited the binding. On the other hand, glycoproteins with non-poly-N-acetyllactosaminyl saccharide chains such as glycophorin A isolated from the erythrocyte membrane, fetuin and alpha 1-acid glycoprotein, little or partially inhibited the binding. The inhibitory activity of band 3 oligosaccharides and lactoferrin oligosaccharides was little affected by treatment with endo-beta-galactosidase, which specifically cleaves poly-N-acetyllactosamine to shorter oligosaccharides. Removal of the nonreducing terminal region of the saccharide chains of band 3 on the erythrocyte surface by treatment of the cells with endo-beta-galactosidase resulted in a decrease in the susceptibility of the cells to the THP-1 cell binding. These results suggest that THP-1 cells which have been differentiated into macrophages bind the oxidized erythrocytes primarily through the recognition of poly-N-acetyllactosaminyl saccharide chains of band 3, and the site of the recognition exists in the nonreducing terminal region of the saccharide chains. Clustering of band 3 molecules is proposed as a possible alteration of oxidized erythrocyte membrane which promotes the interaction of the saccharide receptor on THP-1 cells with the saccharide chains of band 3 on erythrocytes.

Binding characteristics of human lactoferrin to the human monocytic leukemia cell line THP-1 differentiated into macrophages

The characteristics of the binding of human lactoferrin (LF) to the cells of a human monocytic leukemia cell line, THP-1, were investigated. 125I-Labeled LF (125I-LF) bound to THP-1 cells, and the binding increased markedly as the cells matured into macrophages (THP-1 macrophages) by stimulation with phorbol 12-myristate 13-acetate. Scatchard analysis of the binding of 125I-LF to THP-1 macrophages indicated that high and low affinity receptor sites (Kd = 0.57 x 10(-6) and 3.7 x 10(-6) M, respectively) are present on the cells. The number of these high and low affinity receptor sites were 2.4 x 10(6), and 2.5 x 10(6) per cell, respectively. Removal of iron from 125I-LF did not affect its binding to THP-1 macrophages, indicating that the binding is not dependent on Fe(III) ion. The binding of the labeled LF to THP-1 macrophages was markedly decreased following acetylation, suggesting that the amino residues of the polypeptide portion of LF play a major role in the binding. The binding of labeled LF was partially inhibited by the isolated whole oligosaccharides of LF, and by the isolated whole oligosaccharides of band 3 glycoprotein of human erythrocyte membrane which contain poly-N-acetyllactosaminyl saccharide chains, like the LF oligosaccharides. Their inhibitory activity did not depend on the terminal sialyl residues of the saccharide chains. Lacto-N-fucopentaose III and lacto-N-neotetraose, an analogous structure being present in the poly-N-acetyllactosaminyl chains of LF, also artially inhibited the binding of 125I-LF to the THP-1 macrophages. When poly-N-acetyllactosaminyl saccharide chains of 125I-LF were cleaved by endo beta-galactosidase, the binding of 125I-LF was partially reduced. These results suggest that binding of LF to THP-1 macrophages is primarily mediated by its protein component, but a short oligosaccharide structure, possibly Gal beta 1-4GlcNAc beta 1-3Gal, which is contained in the nonreducing terminal region of poly-N-acetyllactosaminyl saccharide chains of LF and band 3, and in lacto-N-fucopentaose III and lacto-N-neotetraose is also recognized by THP-1 macrophages, and this recognition partly contributes to the binding of LF to cells.

Urinary excretion of thiobarbituric acid reactive substances of healthy subjects supplemented with a high dose of d-alpha-tocopherol

The level of urinary thiobarbituric acid reactive substances (TBARS) consisting of bound forms of malonaldehyde and, to a lesser extent, other aldehydes is one of the indices of lipid peroxidation status. Levels of urinary TBARS in healthy subjects before and after supplementation with a high dose of d-alpha-tocopherol were measured using high performance liquid chromatography. Four healthy Japanese were given a supplement of 300 mg d-alpha-tocopherol/d, about 40-fold higher than the normal intake recommended, for a period of 50 d. Levels of urinary TBARS (nmol/kg body weight.h) within-day, before and after supplementation with d-alpha-tocopherol, exhibited similar behavior and levels of daily urinary TBARS (nmol/kg body weight.d) were unchanged by d-alpha-tocopherol supplementation. These results indicate that supplementation with a high dose of d-alpha-tocopherol does not affect the level of urinary TBARS.

Recognition of sialosaccharide chains of glycophorin on damaged erythrocytes by macrophage scavenger receptors

Binding of mouse erythrocytes oxidized in vitro mildly with diamide, periodate or ADP/Fe3+, and the erythrocytes incubated in vitro in a serum-free medium for 12 h (in vitro aged erythrocytes) to mouse peritoneal macrophages was effectively inhibited by isolated glycophorin A, a major sialoglycoprotein of human erythrocyte membrane existing as oligomers in solution, and some of known ligands for macrophage scavenger receptors such as maleyl-BSA, dextran sulfate, fucoidan and polyinosinic acid. Binding of oxidized low density lipoprotein (ox-LDL) to macrophages was inhibited by glycophorin A as well as the known ligands. When the sialyl residues of the saccharide chains of glycophorin A were cleaved by neuraminidase, or the polypeptide of glycophorin A was digested by Pronase, which would destroy its oligomeric forms, the inhibitory effect of glycophorin A was decreased, suggesting that isolated glycophorin A binds to scavenger receptors depending on its sialyl residues and oligomeric structure. Glycopeptides prepared from the N-terminal region of glycophorin A containing most of the sialosaccharide chains of the molecule inhibited the binding of ox-LDL although the potency was lower than that of glycophorin A. N-Acetylneuraminic acid at a high concentration also inhibited the ox-LDL binding. Uptake and degradation of 125I-labeled ox-LDL by macrophages was inhibited by glycophorin A, N-acetylneuramin lactose, as well as the known ligands. 125I-labeled glycophorin A bound to macrophages, and the binding was inhibited by the unlabeled glycophorin A and the known ligands. Inhibitory activity of the unlabeled glycophorin A against the labeled glycophorin A-binding was lowered by neuraminidase and Pronase treatment. These results suggest that oxidized and in vitro aged mouse erythrocytes are recognized by scavenger receptors of mouse peritoneal macrophages, and the cell surface components recognized are sialosaccharide chains of glycophorin, possibly glycophorin A counterpart of mouse erythrocytes which clustered or aggregated in the membrane. The finding indicates that the cell surface sialosaccharides can be ligands for scavenger receptors when cells undergo denaturation by oxidative stress or other damaging effects.

Binding and uptake of oxidized low density lipoprotein (LDL) by macrophage scavenger receptors are enhanced by substrate-bound fibronectin

The uptake of oxidized low density lipoprotein (ox-LDL) by macrophages and the resulting accumulation of low density lipoprotein (LDL) lipids within the cells has been implicated in the pathogenesis of atherosclerosis. The effect of fibronectin (FN) on the binding and uptake of ox-LDL by macrophages was investigated using thioglycollate-induced mouse peritoneal macrophages. The ability of the macrophages to bind ox-LDL was assessed by the binding of mouse red blood cells (RBC) pre-coated with ox-LDL (ox-LDL-RBC) prepared in vitro to macrophages at 37 degrees C. The binding of ox-LDL-RBC to macrophages was significantly enhanced when the macrophages were plated on a FN-coated substrate. Similar enhancement was observed when the macrophages were plated on a substrate pre-coated with Gly-Arg-Gly-Asp-Ser-Pro (GRGDSP) peptide, an adhesive sequence of FN involved in binding to the cells, but not with the control Gly-Arg-Gly-Glu-Ser-Pro (GRGESP) peptide. The effect of FN was inhibited when GRGDSP, but not GRGESP, was present during the macrophage attachment to the FN-coated substrate, suggesting that the specific interaction of this sequence and the FN-receptor is responsible for the effect of FN. The addition of FN or GRGDSP in solution to the macrophage layers on an uncoated substrate was ineffective. Thus, attachment to a substrate is necessary for FN to be effective on the macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for accumulation of lipid hydroperoxides during the aging of human red blood cells in the circulation

Young and old human red blood cells (RBC) were separated from freshly collected human blood by Percoll density gradient centrifugation. The amounts of lipid peroxidation products in the lipid fractions of these RBC were determined by high performance liquid chromatography-chemiluminescence, thiobarbituric acid and LPO-586 methods. The levels of phosphatidylcholine and phosphatidylethanolamine hydroperoxides in old RBC were higher than in young RBC. The products reflecting the advanced stage of lipid peroxidation, malonaldehyde (free and bound forms), 4-hydroxyalkenals (free and bound forms) and other aldehydes, were also higher in old RBC than in young RBC. The levels of these lipid peroxidation products increased when whole RBC were mildly oxidized with ferric ion. These results indicate that oxidative damage of RBC in the circulation takes place during the aging process, and lipid hydroperoxides and other lipid peroxidation products accumulate in old RBC.

Uptake by macrophages of low-density lipoprotein damaged by nitrogen dioxide in air

In order to know whether nitrogen dioxide, an environmental and endogenous free radical toxin, can participate in the formation of atherosclerotic lesions, damage to low-density lipoprotein (LDL) by nitrogen dioxide and uptake of the damaged LDL by macrophages were investigated. A solution of LDL at pH 7.5 was exposed to an atmosphere of nitrogen dioxide (70 ppm) in air at 37 degrees C for 5 or 10 h. Lipid oxidation was induced by the exposure as assessed by the formation of thiobarbituric acid reactive substances. Apolipoprotein B was covalently cross-linked via nondisulfide bonds. Fluorescence analysis showed that tryptophan residues were extensively decreased, and amino acid analysis indicated that the contents of histidine, lysine, and tyrosine residues were decreased by 30-40, 10-20, and 20-30%, respectively. Binding of LDL to thioglycolate-induced mouse peritoneal macrophages was markedly increased by the exposure as observed by the binding of mouse erythrocytes coated with LDL. The activity of LDL to convert macrophages into lipid-laden foam cells was also increased by the exposure. Modification of lysine residues of apo B with lipid oxidation products formed by the exposure may be responsible for the uptake by macrophages. The results suggest the possibility that exposure of LDL in vivo to nitrogen dioxide participates in the formation of atherosclerotic lesions.

Extraction and purification of yellow-fluorescent lipofuscin in rat kidney

Yellow fluorescent lipofuscin deposited in rat tissues was extracted in an aqueous solution. Yellow fluorescence with fluorescence maxima at 400/615-620 nm was detected in the aqueous extracts of brain and kidney of older rats. Purification and characterization of the yellow fluorescent components extracted from rat kidney were attempted. Centrifugal fractionation of the extract revealed that the flourescence was detected in the 105,000 g supernatant, and not in nuclei, mitochondria, lysosomes, microsomes and cell debris. Gel filtration of the supernatant through Sephadex columns gave at least 5 yellow fluorescent components with different molecular weights. The higher-molecular-weight components were converted into the smaller ones on treatment with alkali or ethanol, but may not be on protease treatment. These components were adherent to polymers composed of sugars. They were soluble in water and not in an organic solvent. While the yellow fluorophores were stable on borohydride treatment, they were destroyed on heavy metal ion treatment. The characteristics of the yellow fluorophores were different from those of bluish lipofuscin-like fluorophores generated by lipid peroxidation.

[A clinical and experimental study of dorsiflexed intercalated segmental instability in a scaphoid fracture]

The purpose of this study was to clarify the pathomechanics of dorsiflexed intercalated segmental instability (DISI) in a scaphoid fracture. Twenty two patients with a scaphoid fracture were used for the clinical study. DISI was recognized in 6 patients. There was no statistically significant difference between the DISI(+) group and the DISI(-) group in total ROM, or in grip strength. In the DISI(+) group, however, ROM shifted dorsally (p < 0.05). Clinical factors for DISI were as follows. (1) pseudoarthrosis without treatment: 2 cases; (2) bone union taking place in a humpbacked position: 3 cases; (3) resection of proximal fragment: 1 case. Two fresh cadavers were used for the experimental study. In one cadaver which received simple osteotomy of the scaphoid, DISI was not seen after 216,000 repeated wrist movements (15 times/min., 10 days). In the other cadaver which underwent a volar wedge osteotomy of the scaphoid, the proximal fragment of the scaphoid and the lunate dorsiflexed temporarily under axial compression force immediately after surgery. After 8 days (172,800 repeated movements), static DISI could be seen without axial compression force. These results suggested that a volar bone defect was important for DISI after a scaphoid fracture. When an axial compression force was added, both the proximal fragment of the scaphoid and the lunate could be dorsiflexed in proportion to the volar bone defect due to the linkage between the proximal fragment and the lunate. Loosening in the surrounding tissue occurred gradually during continuous wrist movement and static DISI was finally observed. Therefore, immediate and proper treatment should be recommended to prevent mal-union as well as non-union.

Presence of membrane-bound proteinases that preferentially degrade oxidatively damaged erythrocyte membrane proteins as secondary antioxidant defense

Human erythrocytes were oxidized with xanthine/xanthine oxidase/ferric ion or ADP/ferric ion at 37 degrees C for several hours. Band 3 protein and spectrin of the oxidized cells were found to be significantly modified as analyzed by radiolabeling with tritiated borohydride. Sodium dodecylsulfate-polyacrylamide gel electrophoresis of the xanthine/xanthine oxidase/ferric iron-oxidized cells and subsequent immunoblotting with anti band 3 protein showed that band 3 protein was fragmented into smaller molecular-weight fragments. When the cell membrane obtained from the oxidized cells were incubated at pH 7.4 and 37 degrees C for several hours in the presence of alpha-tocopherol, extensive degradation of band 3 protein and spectrin was observed. Band 3 protein was found to be most susceptible to the degradation. Degradation of band 3 protein was also observed after similar incubation of the membrane from the ADP/ferric ion-oxidized cells. Membrane-bound serine- and metalloproteinases were responsible for the degradation of band 3 protein, because the degradation was remarkably inhibited by diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride, and partially by ethylenediaminetetraacetic acid. Hence, the membrane proteins became susceptible to membrane-bound proteinases by oxidative stress. This observation suggests that these membrane-bound proteinases exist to remove oxidatively damaged proteins from the cell membrane.