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.

Mechanism of macrophage recognition of SH-oxidized erythrocytes: recognition of glycophorin A on erythrocytes by a macrophage receptor for sialosaccharides

Mouse erythrocytes treated with diamide, an SH-oxidizing agent, attach to mouse resident peritoneal macrophages in the absence of serum. The mechanism by which macrophages recognize the SH-oxidized erythrocytes was investigated. Although phosphatidylserine-liposomes inhibited the macrophage recognition, there was no detectable phosphatidylserine on the outer surface of diamide-treated erythrocytes. It is unlikely that phosphatidylserine, that has been proposed to be a determinant in the recognition of some pathologic erythrocytes by macrophages, is involved in the recognition of diamide-treated erythrocytes. Sialyl lactose and glycophorin A effectively inhibited the macrophage recognition, while lactose and neuraminidase-treated glycophorin A did not. Disialoganglioside GD1a, but not monosialoganglioside GM1, partially inhibited the recognition. Trypsinized erythrocytes, in which majority of glycophorin A glycopeptides were expected to be removed from the cell surface, poorly attached to macrophages after diamide treatment. Therefore, it is likely that an interaction between glycophorin A on diamide-treated erythrocytes and a macrophage receptor for sialosaccharides is involved in the recognition. Similar inhibition specificity was observed in the macrophage recognition of erythrocytes treated with periodate, an oxidant that induces disulfide-dependent erythrocyte changes causing macrophage recognition, and of erythrocytes treated with SH-blocking agents, N-ethylmaleimide and p-chloromercuribenzoic acid, that were also found to be susceptible to macrophage recognition in the absence of serum. These results suggest that the macrophages recognize sialosaccharide chains of glycophorin A molecules on SH-oxidized or SH-blocked erythrocytes through a receptor for sialosaccharides.

Involvement of sialylated poly-N-acetyllactosaminyl sugar chains of band 3 glycoprotein on senescent erythrocytes in anti-band 3 autoantibody binding

When young and senescent erythrocytes, separated from freshly collected human blood, were incubated with 125I-goat anti-human IgG, binding of the IgG to the senescent cells was three times as high as that to the young cells. The release of the radioactivity from the anti-human IgG-bound senescent cells was enhanced by incubation with band 3 oligosaccharides but not by those digested with endo-beta-galactosidase or neuraminidase. The senescent cells whose surface band 3 saccharide chains were cleaved by endo-beta-galactosidase or totally removed by N-glycosidase F showed decreased binding of the anti-human IgG. The radioactivity was effectively released from the anti-human IgG-bound senescent cells by digestion with endo-beta-galactosidase. The results suggest that senescent erythrocytes bind anti-band 3 autoantibody, and the antigenic sites on the cell surface are sialylated poly-N-acetyllactosaminyl sugar chains of band 3 glycoprotein.

Macrophage recognition of saccharide chains on the erythrocytes damaged by iron-catalyzed oxidation

Mouse erythrocytes oxidized with an iron catalyst ADP/Fe3+ chelate attached to the monolayers of mouse resident and thioglycollate-induced peritoneal macrophages in the absence of serum, indicating that the macrophages recognized the oxidized erythrocytes. The recognition was partially prevented when the oxidized cells were treated with dithiothreitol, suggesting that disulfide formation is involved, in part, in the generation of the membrane sites recognized by macrophages. Phosphatidylserine is unlikely to be the determinant on the oxidized cells because it was not detected on the outer surface of the oxidized cells. The recognition by resident macrophages was effectively inhibited by N-acetylneuramin lactose, N-acetylneuraminic acid, glycophorin A, and disialoganglioside GD1a, but poorly by lactose, asialoglycophorin A, and monosialoganglioside GM1. In addition, the recognition was partially inhibited by L-fucose and human lactoferrin. The recognition by thioglycollate-induced macrophages was not inhibited by glycophorin A but was partially inhibited by L-fucose, lactoferrin, and oligosaccharides from band 3 glycoprotein. Enzymatic cleavage of the poly-N-acetyllactosaminyl saccharide chains of band 3 and lactoferrin resulted in a loss of the inhibitory activity. These results suggest that sialosaccharide chains of ADP/Fe(3+)-oxidized erythrocytes, possibly those on glycophorin A, are mainly involved in the recognition by resident macrophages, and poly-N-acetyllactosaminyl saccharide chains, possibly those on band 3, are partly involved in the recognition both by resident and thioglycollate-induced macrophages. Oxidation of erythrocytes may induce change in these membrane glycoproteins, like aggregation, which renders their saccharide chains susceptible to the macrophage recognition.

Accumulation of autofluorescent yellow lipofuscin in rat tissues estimated by sodium dodecylsulfate extraction

Autofluorescent yellow lipofuscin accumulated in the older Wistar rat brain, kidney, spleen and testis was successfully extracted by use of 0.5% sodium dodecylsulfate (SDS)/0.05 M phosphate buffered saline (pH 7.4). The extracts contained three fluorophores, one of which corresponded to yellow lipofuscin and showed an excitation maximum at 400 nm and an emission maximum at 620 nm. The SDS extraction method was found suitable for the accurate quantification of lipofuscin in rat tissues. Lipofuscin thus determined accumulated in brain, kidney, spleen and testis with the increase of age of rats. It was found that kidney was the most susceptible tissue in lipofuscin accumulation, and accumulation in male rat kidney was much higher than that in female rat kidney. Accumulation of lipofuscin in rat tissues was slightly dependent on the lipid peroxidation state of the tissues and the dietary conditions: a vitamin E-adequate, vitamin E-deficient, vitamin E-excessive and oil-rich diet, except that the accumulation in male and female rat kidney was significantly enhanced when fed a vitamin E-deficient diet for 7-10 weeks.

Postoperative results of vascularized double fibula grafts for femoral pseudoarthrosis with large bony defect

In open femoral bone fractures osteomyelitis may develop as a complication. Many difficulties are experienced in the treatment of those fractures because an extended bone defect may be formed after repeated operations, and then amputation of the femoral bone becomes necessary. Since 1981 the present authors have performed the vascularized double fibula grafts in the treatment of 18 patients with successful results. With this grafting method, both vascularized double fibula grafts are collected at the same time, one as an intramedullary graft and the other as an onlay graft. The most important point in carrying out grafting by this method is to prepare the recipient bone bed adequately. In many cases, it is necessary to carry out the primary operation to curette the focus, and resect necrotic tissues and sequestrated bone before the vascularized double fibula grafts, and then grafting is performed as a second operation after infection has been controlled following the initial operation. Although differences in time required for recovery cannot be eliminated completely, it becomes possible for 16 out of 18 patients to walk without the use of a brace and crutches within 13 months on average.

A simple method for the assessment of macrophage scavenger receptor-ligand interaction: adherence of erythrocytes coated with oxidized low density lipoprotein and modified albumin to macrophages

A simple method is described for the assessment of the binding of macrophage scavenger receptor and its ligands such as oxidized low density lipoprotein (ox-LDL) and maleylated bovine serum albumin (m-BSA). In this method, the binding of ox-LDL or m-BSA to macrophages is observed as the adherence of erythrocytes precoated with ox-LDL or m-BSA under phase-contrast microscopy. Erythrocytes were coated with native LDL or ox-LDL simply by incubating mouse erythrocytes with LDL. The ox-LDL-coated erythrocytes attached to the monolayer of mouse peritoneal macrophages without phagocytosis at 37 degrees C, while native LDL-coated erythrocytes did not. The extent of the adherence of the ox-LDL-coated erythrocytes to the macrophages was conveniently expressed as the proportion of the macrophages binding the coated erythrocytes. An optimal concentration of ox-LDL for erythrocyte coating giving maximum erythrocyte adherence to macrophages was 10 micrograms/ml as protein at an erythrocyte concentration of 2%. The binding of the ox-LDL-coated erythrocytes to the macrophages could be inhibited by ligands for scavenger receptor, and reflected the extent of LDL oxidation. Mouse erythrocytes were successfully coated with m-BSA using chromium(III) ion as adsorbent. The m-BSA-coated erythrocytes attached to the macrophages, while native BSA-coated erythrocytes did not. The adherence was inhibitable with ligands for scavenger receptor, and reflected the extent of maleylation. The method would be useful particularly for measurement of the ligand-binding activity of the receptor, and the receptor-binding activity of the ligands.

Modification of delipidated apoprotein B of low density lipoprotein by lipid oxidation products in relation to macrophage scavenger receptor binding

It is known that macrophages recognize and take up oxidized low density lipoprotein (LDL) and this macrophage recognition has been suggested to be due to modification of the lysine (Lys) residues of apoprotein B (apo B). In order to determine whether such modification is involved in recognition, delipidated apo B was modified with lipid peroxidation products and the macrophage recognition of the modified apo B was examined. When delipidated apo B was treated with linoleic acid 13-mono-hydroperoxide (LOOH) and trans-2-octenal (octenal), apo B became fluorescent and its Lys and histidine (His) residues were decreased. When delipidated apo B, partially methylated at the epsilon-amino groups of Lys residues, was treated with LOOH and octenal, fluorescence was not produced and the free Lys residues were not decreased. LOOH- and octenal-modified delipidated apo B were recognized by mouse peritoneal macrophages. The macrophage recognition of the modified apo B was prevented by maleyl bovine serum albumin, indicating that the scavenger receptor was involved in recognition. Neither methyl apo B nor methyl apo B, modified with LOOH or octenal, was recognized by macrophages. Neutralization of positively charged Lys residues of apo B by modification with LOOH and octenal may be requisite for recognition. Bovine serum albumin modified with LOOH and octenal prevented the recognition of the modified apo B, indicating that none of the intrinsic structure of apo B is required for recognition.

Increased susceptibility of stored erythrocytes to anti-band 3 IgG autoantibody binding

When human blood was stored in a citrate-phosphate-dextrose (CPD) solution at 4 degrees C, the susceptibility of the erythrocytes to binding of autologous IgG increased. The autologous IgG binding was partially inhibited by purified Band 3 glycoprotein and its oligosaccharides. The susceptibility of the erythrocytes to binding of 125I-labeled anti-band 3 IgG autoantibody similarly increased. The results indicate that the anti-band 3 binding sites composed of Band 3 oligosaccharides were generated on the cell surface. The rate of the increase in the susceptibility of the stored cells to the antibody binding was lowered when blood was stored in a CPD solution containing L-ascorbic acid or erythorbic acid, suggesting involvement of an oxidative mechanism in the generation of the binding sites. The cytoplasmic glutathione level of erythrocytes gradually decreased during the blood storage. Storing blood in a CPD solution containing glutathione monoethylester or glutathione monoisopropylester resulted in partial prevention of the decrease in cytoplasmic glutathione level and of the increase in the IgG-binding ability of the cells. Similar preventive effect of glutathione monoethylester was observed in the binding of 125I-labeled anti-band 3 autoantibody to the stored erythrocytes. Thus, the increase in the susceptibility of the stored erythrocytes to anti-band 3 binding may be caused, at least partially, by an oxidative stress resulting in a decreased cytoplasmic glutathione level.

Energy storing property of so-called energy-storing prosthetic feet

The purpose of this study is to evaluate the energy storing and releasing property of 14 different prosthetic feet, in which so-called energy storing prosthetic feet are included. The prostheses were fitted to a young male amputee who walked on a level and slope walkway. Gait-analysis data were obtained by an automatic gait measurement system from which the ankle moment and ankle angular velocity were calculated. From these values, the power and the energy at the ankle joint were calculated. The prosthetic feet were ranked according to the total amount of energy, that is the sum of energy being stored and released. Both of the stored and released energy are important feature of the prosthetic feet. According to these evaluation criteria, we ranked the feet into three groups. The high total energy feet were Flex-Walk,a SAFE II,b and High Functionc. The medium total energy feet were SAFE,b Greissinger,d Seattle,e Copy II,f and Dynamic.d The low total energy feet were Seattle Light,e Fore Joint,g Quantum,h SACH,dSTEN,i and Uniaxial.d As for the subjective feeling, our subject preferred higher energy absorbing feet, in which a somewhat high level of energy was stored but low level of energy was released.

Antigenic determinants of senescent antigen of human erythrocytes are located in sialylated carbohydrate chains of Band 3 glycoprotein

Naturally occurring IgG autoantibody against Band 3 glycoprotein of human erythrocyte membrane (anti-Band 3) recognizes the erythrocytes modified with oxidizing or SH-blocking agents as well as senescent erythrocytes. Location of the antigenic determinants of Band 3 this autoantibody recognizes was investigated by competitive inhibition studies of the antibody binding to the modified cells. Autologous IgG binds to the modified erythrocytes, and purified Band 3 totally inhibits the binding. This inhibitory activity of Band 3 was not affected by digestion of Band 3 with various proteases. Treatment of Band 3 with endo-beta-galactosidase that destroys the poly-N-acetyllactosaminyl sugar chain of Band 3 or with neuraminidase resulted in loss of the inhibitory activity. Oligosaccharides released from Band 3 by hydrazinolysis effectively inhibited the binding of autologous IgG and 125I-labeled purified anti-Band 3 to the modified cells, whereas the oligosaccharides depleted of acidic components did not. Endo-beta-galactosidase and neuraminidase destroyed the activity of the oligosaccharides, but alpha-L-fucosidase did not. Furthermore, human lactoferrin that contains sialylated two N-acetyllactosaminyl units also exhibited potent inhibitory activity, and the activity was destroyed by endo-beta-galactosidase and neuraminidase. These results indicate that the antigenic determinants of Band 3 are located in sialylated poly-N-acetyllactosaminyl sugar chains. Based on this finding, mechanism of appearance of the antigen on senescent erythrocytes recognized by anti-Band 3 (senescent antigen) was discussed.

Generation of senescent antigen on erythrocytes by partial blocking of SH groups of the membrane proteins

Human erythrocytes treated with diamide (0.2 mM) or N-ethylmaleimide (0.1 mM) at 37 degrees C for 1 h were susceptible to binding of anti-band 3 immunoglobulin G autoantibody and hemoglobin. A definite degree of cell modification appeared to be required for the effective bindings since the cells treated with the reagents above these concentrations were less susceptible. The enhanced binding activities of the cells treated with diamide were abolished on treatment with dithiothreitol. Partial blocking of SH groups of the membrane proteins but not disulfide-mediated protein cross-linking may be essential for the formation of band 3 senescent antigen, which may not be a neo-antigen formed by chemical modification of band 3 but an antigen formed by topological alterations of the molecules in the membrane.

The osteocutaneous fibula flap: an anatomic study

Recent studies related to the fibula flap have disagreed regarding the anatomy of the cutaneous branches of the peroneal artery. To clarify this issue, various dissections of 35 injected fresh cadaver legs were done. Identifiable skin branches were found in 23 of 25 dissections. Skin branches from the proximal third of the peroneal artery always travelled an intramuscular course. Skin branches from the distal two-thirds of the peroneal artery were usually affixed to the posterior crural septum. Legs with peroneal artery skin branches had from three to seven branches (average: 4.7); each branch contributed to the fibular periosteal blood supply. The most reliably found skin branch was located within 2 cm of the fibula midpoint. These findings reinforce the fact that a large skin island supplied by branches of the peroneal artery can be harvested with the fibula flap, and that the most reliable cutaneous vessels are found in the lower two-thirds of the leg, run posterior to the fibula in the posterior crural septum, and are always associated with muscular side branches.

Augmentation of macrophage recognition of oxidatively damaged erythrocytes by substratum-bound fibronectin and macrophage surface fibronectin

Thioglycollate-induced mouse peritoneal macrophages plated on a coverglass bind oxidized mouse erythrocytes in the absence of serum. Macrophages plated on a coverglass pre-coated with fibronectin (FN) were more active in binding of the oxidized erythrocytes. This effect of FN-coated coverglass was due to specific binding of an RGD-containing sequence of FN to FN-receptors on the macrophage, since GRGDSP hexapeptide in solution inhibited this effect, and GRGDSP-coated coverglass exhibited the same effect as FN-coated coverglass. Removal of FN originally present on the macrophage surface by trypsinization, prior to attachment to the coverglass, resulted in diminution of their ability of recognition of the oxidized erythrocytes, but the diminished ability was restored when the trypsinized macrophages were plated on a FN-coated coverglass, indicating that the cell surface FN is required for the macrophage recognition. Attachment to the coverglass was necessary for the cell surface FN to be effective. These results suggest that solid-phase FN, produced either by deposition of soluble FN to substratum or attachment of macrophage surface FN to substratum, activates the macrophages and augments their ability to recognize the oxidized erythrocytes.

Hepatic subsegmentectomy with segmental hepatic vein sacrifice

There is no clinical disorder in partial Budd-Chiari syndrome or in a major hepatic vein ligation in hepatic trauma. When considering these findings, it is significant to investigate hepatic subsegmentectomies in which a major hepatic vein is sacrificed. We performed such hepatic subsegmentectomies in nine cases of hepatocellular carcinoma. With the sacrifice of the right hepatic vein, S7, S8 resection was done in three patients, S7 resection in two patients, S8 resection in one patient, and S5 resection in one patient. With the sacrifice of the middle hepatic vein, S8 resection was done in two patients. These resections were successfully performed with no postoperative problem. Further, there were no significant differences in postoperative liver function tests of the patients from those of a control group of the commonly performed systematic segmentectomy and subsegmentectomy. By performing such resections, resection was made possible in three cases and curative resection was made feasible in six cases.

Metabolism in vivo of 3,4,5,3',4'-pentachlorobiphenyl and toxicological assessment of the metabolite in rats

Metabolism in vivo of 3,4,5,3',4'-pentachlorobiphenyl (PenCB) and toxicological assessment of the metabolite were investigated using male Wistar rats. Only one metabolite was isolated from the feces of rats administered 3,4,5,3',4'-PenCB. By gas chromatography-mass spectrometry, the methylated metabolite was identified with the synthesized authentic sample, 4'-methoxy-3,4,5,3',5'-PenCB. This indicated that the metabolite was 4'-hydroxy-3,4,5,3',5'-PenCB, which was produced via a 4',5'-epoxide formation and subsequent NIH-shift of the 4'-chlorine to the 5'-position. Administration of the metabolite at either single i.p. dose of 3 or 10 mg/kg to rats did not cause any toxic and biological effects such as body weight loss, atrophy of thymus and spleen, liver hypertrophy, increase of liver lipids, or 3-methylcholanthrene-type induction of liver enzymes. These changes were observed in rats administered with 3,4,5,3',4'-PenCB at a single dose of 3 mg/kg. In addition, a trace amount of 4'-hydroxy-3,4,5,3',5'-PenCB could be detected in rat liver 5 d after treatment with 3,4,5,3',4'-PenCB or 4'-hydroxy-3,4,5,3',5'-PenCB. The amount of this metabolite excreted in feces during 5 d after treatment with 3,4,5,3',4'-PenCB accounted for only 1.3% of dose. In 4'-hydroxy-3,4,5,3',5'-PenCB-treated rats, about 60% of dose was excreted as unchanged in feces for 5 d. These results suggest that this metabolite is a detoxified product and has no longer the high affinity for the liver, being excreted rapidly into the feces.

Modification of glycophorin A during oxidation of erythrocyte membrane

Human erythrocyte ghosts were oxidized with tert-butyl hydroperoxide and subsequently treated with tritiated borohydride to label the membrane proteins modified during the membrane oxidation. From the ghosts, oxidized-and-tritiated glycophorin A was isolated and characterized. No intermolecular cross-links were observed as analyzed by sodium dodecylsulfate gel electrophoresis. But, the number of lysine residues was significantly reduced and susceptibility to proteinases such as trypsin, chymotrypsin and pronase was lower than that of control glycophorin A. Trypsinization of the oxidized-and-tritiated glycophorin A gave insoluble and soluble trypsin fragments. After dansylation, N-terminal amino acids of the trypsin-fragments were determined. Dansyl amino acids from the insoluble trypsin fragments were not identical with those from control insoluble counterparts in the membrane-spanning region of glycophorin A molecule. Fractionation by gel filtration of dansyl-soluble trypsin fragments, and the N-terminal amino acid analysis of the fractionated peptides indicated that the peptides derived from the glycosylated region located in the outside of the membrane matrix were identical with those from control soluble counterparts. The results suggest that the glycosylated outside region of glycophorin A was modified only slightly but the hydrophobic membrane-spanning region was extensively modified during membrane oxidation, most likely by oxidized lipids.

Binding of anti-band 3 autoantibody to oxidatively damaged erythrocytes. Formation of senescent antigen on erythrocyte surface by an oxidative mechanism

Incubation of human erythrocytes oxidized by iron catalysts, ADP/Fe3+ or xanthine/xanthine oxidase/Fe3+, with autologous IgG resulted in IgG binding as detected by enzyme immunoassay using protein A-beta-galactosidase conjugate. The binding of autologous IgG to ADP/Fe3(+)-treated erythrocytes maximized when the cells were treated with 1.8:0.1 mM ADP/Fe3+, and declined when treated above this concentration, suggesting that autologous IgG binds to moderately but not to excessively oxidized erythrocytes. The antibody involved in the binding was anti-Band 3, the autoantibody known to bind to aged erythrocytes, because isolated anti-Band 3 bound to the oxidized cells, but anti-Band 3-depleted autologous IgG did not. In addition, purified Band 3 inhibited the autologous IgG binding. Anti-alpha-galactosyl IgG, another natural antibody which has been reported to bind to aged erythrocytes, did not bind to the oxidized cells. Oxidation of membrane lipids, SH-groups of membrane proteins, and Hb of these cells was slight, but the cells contained an increased amount of membrane-bound native Hb, indicating that the oxidized cell membrane has an altered property. alpha-Tocopherol prevented the lipid oxidation and the subsequent IgG binding. Reduction of the oxidized erythrocytes with dithiothreitol resulted in a loss of the IgG binding. These results suggest that anti-Band 3 binding sites (Band 3 senescent antigen) are formed on moderately oxidized erythrocytes as a result of oxidation of membrane protein SH-groups which can be mediated by the membrane lipid oxidation and that formation of the anti-Band 3 binding sites on the oxidized cells is an essentially reversible membrane event which is linked to oxidation and restoration of the protein SH-groups.

Fluorescent and cross-linked proteins formed by free radical and aldehyde species generated during lipid oxidation

One of the mechanisms for the formation of lipofuscin-like fluorescent substances is considered to be related to lipid oxidation of tissues. Induction of lipid oxidation in tissues or cells produces cross-links and borohydride-reducible functions together with fluorescence in proteins. In order to elucidate the structures of fluorophores, cross-links and borohydride-reducible functions produced in proteins by lipid oxidation, the reactions of a lipid peroxy free radical with amino acids and proteins, and those of an aldehyde with primary amines were investigated. We demonstrated here two possible types of the reactions that produce the modified proteins. A peroxy free radical generated during lipid oxidation may attack the tyrosine residue in proteins to form the tyrosine radical which may be in turn dimerized into fluorescent and cross-linked tyrosine dimer. aldehyde species formed by degradation of the peroxy free radical may be polymerized into dimer, trimer, tetramer and so on, which may react with the amino groups of protein to produce fluorescence, cross-links and borohydride-reducible functions. Cross-links can be produced by the formation of Schiff base between the tetrameric dialdehyde and the amino groups of proteins.

Further studies on metabolism in vivo of 3,4,3',4'-tetrachlorobiphenyl in rats: identification of minor metabolites in rat faeces

1. Metabolism in vivo of 3,4,3',4'-tetrachlorobiphenyl (TCB) was investigated in male Wistar rats. 2. Five new minor metabolites in addition to two previously identified major metabolites (5-hydroxy-3,4,3',4'-TCB and 4-hydroxy-3,5,3',4'-TCB) were isolated as methylated derivatives from faeces of rats treated with 3,4,3',4'-TCB, by silica gel column chromatography and subsequent preparative t.l.c. 3. Among these methylated metabolites, three were identified as dimethoxy-TCB, and one as monomethoxy-trichlorobiphenyl (TriCB), by g.l.c.-mass spectrometry. By comparison with synthetic standards they were fully identified as 2,5-dimethoxy-3,4,3',4'-TCB, 4,4'-dimethoxy-3,5,3',5'-TCB, 5,6-dimethoxy-3,4,3',4'-TCB, and 4-methoxy-3,3',4'-TriCB, respectively. The structures of these metabolites in rat faeces should therefore be 2,5-dihydroxy-3,4,3',4'-TCB, 4,4'-dihydroxy-3,5,3',5'-TCB, 5,6-dihydroxy-3,4,3',4'-TCB, and 4-hydroxy-3,3',4'-TriCB. 4. One further metabolite was isolated, which was shown to be an oxepin, existing in a state of equilibration with the 4',5'-oxide of the major metabolite, 4-hydroxy-3,5,3',4'-TCB, by mass and 1H-n.m.r. spectra. On standing for several months, this metabolite isomerized to a new compound with a different g.l.c. retention time, which on methylation yielded a product identical with synthetic 4,4'-dimethoxy-3,5,3',5'-TCB by g.l.c.-mass spectrometry. From these results this metabolite was assumed to be an oxepin, equilibrated with 4-hydroxy-4',5'-epoxy-3,5,3',4'-TCB.

Experimental replantation of canine forelimbs after 78.5 hours of anoxia

To assess the effect of ischemia on osteocyte survival and longitudinal growth in bone, one forelimb of eight puppies and seven dogs was amputated, perfused with iced Collins solution, maintained at 4 degrees C for 72 hours (78.5 hours total anoxia), and replanted. Five puppies were kept for 1 year to assess bone growth. Undergoing bone labeling on days 1, 8, and 15, the other animals were sacrificed at 22 days to assess osteocyte survival. Osteocytes survived replantation in all dogs and one puppy; most osteocytes died in two puppies. In five long-term puppies, central epiphyseal growth was disturbed, but the peripheral portions maintained nearly normal growth, with almost normal bone length being achieved at 1 year.

Macrophage recognition of periodate-treated erythrocytes: involvement of disulfide formation of the erythrocyte membrane proteins

Upon exposure to 2 mM periodate at 0 degrees C for 15 min, mouse erythrocytes underwent membrane lipid oxidation, oxidation of cell surface sialyl residues into aldehyde-bearing derivatives, and oxidation of SH groups of the membrane proteins into disulfides. The periodate-treated erythrocytes exhibited a remarkable increase in rosette attachment to resident mouse peritoneal macrophages in the absence of serum. The relationship between the oxidation of the membrane constituents and the macrophage recognition of these cells was investigated. Periodate treatment of erythrocytes in the presence of butylated hydroxytoluene, an inhibitor of lipid oxidation, did not affect the subsequent attachment of the erythrocytes to the macrophages. Reduction of the periodate-treated erythrocytes with borohydride or cyanoborohydride did not affect the erythrocyte attachment. Neuraminidase treatment of erythrocytes before periodate did not affect the attachment either. On reduction of the disulfides of the membrane proteins with dithiothreitol, the periodate-treated erythrocytes lost their ability to attach to the macrophages. Erythrocytes treated with an SH-oxidizing agent, diamide, were then examined for the macrophage recognition. The diamide-treated cells also showed rosette attachment to the macrophages in the absence of serum, but did not when reduced with dithiothreitol. These results indicate that oxidation of the SH groups of the membrane proteins to disulfides causes reversible membrane changes that macrophages recognize, and it is this mechanism that is responsible for the macrophage recognition of the periodate-treated erythrocytes.

Cell surface fibronectin of mouse peritoneal macrophages

Fibronectin (FN) was detected on thioglycollate-induced mouse peritoneal macrophages by binding the 125I-labeled F(ab')2 fragment of rabbit anti-human plasma fibronectin. The cell surface fibronectin (sFN) was removed from the surface of the macrophage monolayer by limited trypsinization. After trypsinization, binding of 125I-labeled plasma fibronectin (125I-pFN) to the macrophage monolayer was increased, suggesting that the FN receptor covered with sFN was exposed by trypsinization without destroying the receptor activity. The amounts of saturation binding of 125I-pFN to the macrophage monolayers before and after trypsinization were about 2.4 and 6.3 micrograms per 10(6) cells, respectively, indicating that the macrophage monolayer has the capacity of binding 6.3 micrograms FN per 10(6) cells, and the FN receptor equivalent to about 4 micrograms pFN per 10(6) cells is covered with sFN.