Demonstration of peptide-specific and cross-reactive epitopes in proteins reacting with antimitochondrial antibodies of primary biliary cirrhosis

Recently the main targets of antimitochondrial antibodies (AMA) of primary biliary cirrhosis have been identified as parts of three related mitochondrial multienzyme complexes, namely pyruvate dehydrogenase (PDH), branched chain alpha-ketoacid dehydrogenase (BKDH) and alpha-ketoglutarate dehydrogenase (alpha-KGDH). Usually AMA-positive PBC serum samples show reactivity to more than one of these, raising the question whether they are exclusively different antibodies or are, at least in part, the result of cross-reactive specificities. With Western immunoblotting, four antigens with molecular masses of 74, 52, 51 and 43 kDa, are recognized by PBC sera. In this study, using affinity purified antibodies from mitochondrial proteins immobilized on nitrocellulose blots, we demonstrate the presence of peptide-specific and cross-reactive epitopes in some targets. In particular, at least three different epitopes present in the 74-kDa protein (presumed to by PDH-E2) are also present in the 51-kDa protein (probably PDH-X), and two in the 52-kDa peptide (possibly BCKDH-E2). Moreover, the 43-kDa mitochondrial protein (the identity of which is more problematic) has three epitopes. One of these is also present in the 74-, 52- and 51-kDa proteins, a second in the 74- and 51-kDa, and a third seems to be peptide-specific. These results show that different sera with the same immunoblotting pattern of reactivity can have antibodies with different antigenic specificities and, conversely, that the same specificity can be responsible for more than one band.

Purification and characterisation of bovine spleen ADPase

ADPase has been purified from bovine spleen. Electrophoresis revealed a minor contaminent in the preparation that may represent ADPase that has been decreased in size by limited proteolysis during extraction and purification. The native enzyme behaves on SDS/PAGE as a 100-kDa protein but ADPase is a glycoprotein and so its electrophoretic behaviour may be anomalous. The apparent molecular mass is decreased to 70 kDa after removal of carbohydrate by treatment with a glycosidase. The use of a cross-linking reagent followed by electrophoresis suggests that the enzyme is composed of a single subunit. The specific activity of the purified material was 115 U/mg protein. The enzyme catalyses the hydrolysis of nucleoside di- and tri-phosphates but nucleoside monophosphates are not acted upon. The Km for ADP (approx. 10-15 microM) is unaffected by the state of purification of the enzyme, but catalytic activity of the purified material is stimulated by inclusion of detergent in the assay system and by calcium ions. Maximum activity is seen at pH 8.0-8.5 with ADP as substrate but the optimum shifts to 7.5-8.0 for ATP hydrolysis.

The susceptibility of elastin-fatty acid complexes to elastolytic enzymes

Elastin in vivo is likely to be complexed with amphipathic ligands such as lipids. The susceptibility of stable [3H] elastin-fatty acid complexes to the action of porcine pancreatic elastase (PPE) and to human neutrophil lysates over time was assessed. Elastolysis by PPE of substrates prepared with oleic or linoleic acids was initially higher (for up to 2 hours) than that of uncomplexed elastin. Stearic acid and elaidic acid (the trans isomer of oleic acid) did not enhance the elastolytic rate above control. The stimulatory effect of oleic and linoleic acids appeared to derive from increased adsorption of PPE onto elastin; the loss of stimulatory activity over time occurred in parallel with a progressive decrease in adsorption. All fatty acids tested inhibited elastolysis by neutrophil lysates, the effect being particularly marked with oleic and elaidic acids. These results indicate that 1). Complexed fatty acids can modulate the rate of elastin breakdown by elastases; 2). The effects observed with PPE are due to differences in adsorption of enzyme onto substrate, possibly as a result of steric considerations; 3). Since elastolysis by neutrophil lysates is inhibited by all fatty acids, the properties of different elastolytic enzymes should be considered in in vitro model systems of connective tissue breakdown.

Isolation and characterization of a hypervariable region [D4S163] on chromosome 4

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Allergic contact dermatitis from diphenylthiourea in Vulkan heat retainers

11 cases of contact dermatitis from Vulkan heat retainers are reported. The skin eruptions started on days 1-11 after the 1st day of exposure. The clinical picture varied from eczema through urticaria to purpura. In some cases, the symptoms were severe. Patch testing was performed in 10 individuals and all reacted positively to the heat retainer and/or the rubber glue used in the heat retainer. A series of rubber chemicals was patch tested in 7 patients and all showed positive reactions to diphenylthiourea (DPTU), and all but one to ethylene thiourea (ETU). TLC examination revealed a spot with the same RF-value as DPTU in extracts of the adhesive, but no spot corresponding to ETU. There were no indications of impurities in the test preparations of DPTU and ETU. By HPLC, the content of DPTU in the adhesive was determined as 0.6% w/w.

Enhanced adhesion of polymorphonuclear leukocytes to anoxic cultured vascular endothelium

This study showed that the adherence of human polymorphonuclear leukocytes (PMN) to monolayer cultures of human umbilical vein endothelial cells (HUVEC) was increased when the latter were rendered anoxic. This adhesion was greater after 4-5 h than after 8 h of anoxia, but even at 8 h was significantly above the level of adhesion to HUVEC maintained under normoxic conditions for the same period. The changes in adhesion were not dependent on the viability of HUVEC during anoxia. Anoxia-induced adhesion was prevented by addition of cycloheximide (5 micrograms/ml) to the cultures, suggesting that it depended on HUVEC protein synthesis. Enhanced adhesion was also prevented by addition of a monoclonal antibody directed against the cytokine, interleukin-1 alpha (IL-1 alpha). These findings are consistent with a role of endogenous IL-1 alpha as a mediator of the anoxia-induced adhesion of PMN to HUVEC.

Antimitochondrial antibodies in primary biliary cirrhosis recognize both specific peptides and shared epitopes of the M2 family of antigens

Sera from patients with primary biliary cirrhosis exhibit variable autoantibody reactivity against mitochondria, the commonest antigen (designated M2) including three structures of approximate M.W. 70, 50 and 40 kD. The nature of these antigens has only recently been established; the 70 and 50 kD are the transacetylase E2 and component X, respectively, of the pyruvate dehydrogenase complex and are distinct polypeptides. We have demonstrated, by immunoblotting, elution and rebinding of antibodies, unequivocal cross-reactivity between the major bands of the M2 antigen. In addition, cross-reactivity has been shown between antibodies binding to each of the three M2 bands of mitochondria and two major antigenic bands of both Gram-negative and Gram-positive bacteria. Conversely, antibodies eluted from these two bands of Escherichia coli were found to bind all three M2 bands of mitochondria. These results suggest that the antibodies of primary biliary cirrhosis contain both peptide-specific and cross-reacting antibodies, the latter recognizing a common "M2 epitope" that might include nonprotein components of the peptides. However, direct and competitive enzyme-linked immunosorbent assays failed to implicate the coenzyme of the pyruvate dehydrogenase complex, lipoic acid or its amide, as the common antigenic moiety.

Treatment of Wilms' tumor. Results of the Third National Wilms' Tumor Study

The Third National Wilms' Tumor Study sought to reduce treatment for low-risk patients and find better chemotherapy for those at high risk for relapse. Eligible patients (1439) were randomized according to stage (I-IV) and histology (favorable [FH] or unfavorable [UH]), and contributed data to survival and relapse-free survival (RFS) analyses. Four-year (postnephrectomy) survival percentages and randomized treatment regimens for low-risk patients were 96.5% for 607 Stage I/FH patients who received dactinomycin (Actinomycin D [AMD], Merck Sharp & Dohme, West Point, PA) and vincristine (VCR) for 10 weeks versus 6 months; 92.2% for 278 Stage II/FH patients; and 86.9% for 275 Stage III/FH patients who received AMD + VCR +/- Adriamycin (ADR, Adria Laboratories, Columbus, OH) for 15 months. Stage II/FH patients also had either zero or 2000 cGy irradiation (RT) postoperatively and Stage III/FH patients either 1000 or 2000 cGy. Four-year survival was 73.0% for 279 high-risk patients (any Stage IV, all UH) who received postoperative radiation therapy (RT) and AMD + VCR + ADR +/- cyclophosphamide (CPM). Statistical analysis of survival and RFS experience shows that the less intensive therapy does not worsen results for low-risk patients and CPM does not benefit those at high risk.

Iron release from haemosiderin and ferritin by therapeutic and physiological chelators

Iron release from both human and horse spleen haemosiderin to desferrioxamine was substantially less than that released from ferritin samples. This finding contradicts a previous report [Kontoghiorges, Chambers & Hoffbrand (1987) Biochem. J. 241, 87-92]. Differences in phosphate content of cores and in core size between haemosiderin and ferritin did not account for the different iron-release rates. Iron released to acetate was found to stimulate lipid peroxidation in liposomes, whereas that released to stronger chelators such as citrate and desferal did not. Absorption spectra and gel-filtration studies suggest that the acetate-solubilized iron was in the form of low-molecular-mass (less than 5 kDa) ferrihydrite fragments.

Discovery of a novel multilocus DNA polymorphism [DNF24]

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Mitochondrial antigenic structure and enzyme activity in ageing human diploid fibroblasts

It has been proposed that cellular ageing may be caused by loss of mitochondrial function due to the action of free radicals. To investigate this hypothesis, antigenic structures of the mitochondrial inner membrane/matrix and of the outer mitochondrial membrane of human diploid fibroblasts were monitored by immunoblotting at four stages during cellular lifespan in vitro. At the same time, specific activities of the enzymes oligomycin-sensitive ATPase (O-S ATPase), malate dehydrogenase (MDH) and glutamate dehydrogenase (GDH) were assayed to assess the functional capacity of cellular oxidative phosphorylation and of the tricarboxylic acid cycle. No changes were found with ageing in inner mitochondrial membrane-associated matrix components, or in the activities of O-S ATPase and MDH. However GDH activity increased significantly with ageing in vitro, possibly indicating greater amino acid utilization for energy production in older cells. There was loss of an outer mitochondrial membrane antigen, of approximate molecular weight 60 kilodaltons (kDa), in the oldest cells tested, which may influence outer membrane transport capacity late in the cellular lifespan. Overall, the results fail to provide support for the hypothesis that ageing primarily results from free radical-induced impairment of mitochondrial function.

[Contaminating substances in 22 over-the-counter fish oil and cod liver oil preparations: cholesterol, heavy metals and vitamin A]

Fish oil capsules are increasingly used by self-medicating patients. We studied 22 commercial fish oil and menhaden oil preparations in respect to accompanying substances that could be harmful. The substances measured were: cholesterol as determined by gas liquid chromatography, heavy metals measured by atomic absorption, and vitamin A as determined by high-performance liquid chromatography (HPLC). The contents of cholesterol and heavy metals were in ranges which can be regarded as negligible; the content of vitamin A in menhaden oils, however, was found in amounts which warrant that pregnant women do not exceed the dosage as recommended by the manufacturers.

Retained intraspinal bullet--an illustrative case report

In a 35 year old male who had suffered a gunshot injury one bullet remained in the spine at level C 5. Clinically, a complete high tetraplegia was found. Already during the first months after trauma the patient complained of dysaesthesia and hyperaesthesia in the segments at, and above, the lesion. Five years later, when the authors saw the patient, he reported on an increase of intensity of this pain since some months. This gave occasion to radiological investigations to rule out morphological changes as the origin of the increase in pain. CT showed a compact bullet exactly intraspinal, with a syringiform cyst projecting into the myelon. Since former CT scans did not exist, an objective statement on progress could not be given. However, it is suspected that chronic inflammation caused by metal breakdown products of the bullet may have contributed to the increasing pain. It is pointed out that it is necessary to take account the kind of metal when deciding for or against the removal of a foreign body.

Expression of the primary biliary cirrhosis antigens in yeast: aspects of mitochondrial control

The mitochondria of 21 yeast strains were tested for the expression of primary biliary cirrhosis (PBC) specific antigens. The amounts of the antigens in the mitochondrial preparations varied with the strains. Genetic analysis of the strain differences in antigen expression indicated nuclear control which was complex. Those strains expressing the least amounts of antigens exhibited coagulating mitochondria in organellar preparations. Additional evidence relating expression of antigens to the physiological/structural state of mitochondria was that cells grown in the presence of the mitochondrial uncoupling agent, 2,4-dinitrophenol (DNP), failed to produce any antigens, and that glucose repression of mitochondria suppressed antigen expression. Blockage of mitochondrial protein synthesis either through petite mutation or by culture in the presence of erythromycin decreased the content of antigens in the mitochondria but did not completely block antigen production. The presence of the PBC antigen in the mitochondria of these cells with nonfunctional mitochondrial synthesizing machinery further indicates that these antigens are cytoplasmically synthesized. Analysis of the pre- and postmitochondrial fractions of all homogenates confirmed that the antigens are not only cytoplasmically synthesized but also have an extramitochondrial location in cells, probably in the plasma membrane.

[Nuclear magnetic resonance studies of the orbit]

Magnetic resonance tomography enables sensitive and specific three dimensional imaging processes in the bulbus, the soft parts of the orbita and the optic foramen as well as their relation to intracerebral structures. Besides a very exact imaging of the morphology it is also possible to characterise the tissue, this being a decisive factor in arriving at a correct diagnosis.

Heterogeneity of antimitochondrial antibodies with the M2-M4 pattern by immunofluorescence as assessed by Western immunoblotting and enzyme linked immunosorbent assay

Seventy seven sera with antimitochondrial antibody exhibiting the M2-M4 pattern in immunofluorescence (56 from primary biliary cirrhosis (PBC), 21 from non-primary biliary cirrhosis patients) were studied by the combined use of Western immunoblotting with beef heart mitochondria and an enzyme linked immunosorbent assay (ELISA) with beef heart submitochondrial particles. Forty seven sera (10 without autoantibodies and 37 with different auto-antibodies) were included as controls. By immunoblotting, seven mitochondrial peptides reacting with antimitochondrial antibody positive sera were detected. These were of molecular weight 74 kD, 58 kD, 55 kD, 52 kD, 51 kD, 46 kD, and 43 kD. All primary biliary cirrhosis sera and 71% of antimitochondrial antibody-positive non-primary biliary cirrhosis sera reacted with one or more of these peptides, while none of the 47 antimitochondrial antibody negative sera reacted in immunoblotting. The 74 kD band was the most frequently detected (84% of primary biliary cirrhosis and 57% of non-primary biliary cirrhosis cases). All the primary biliary cirrhosis sera which failed to react with this peptide, showed a positive reaction with that of molecular weight 52 kD. 67/77 (87%) immunofluorescence antimitochondrial antibody positive sera reacted in the ELISA test (93% of primary biliary cirrhosis and 71% of non-primary biliary cirrhosis cases). All the 47 immunofluorescence antimitochondrial antibody negative sera were confirmed negative by ELISA. The ELISA values correlated with the immunofluorescence titres (p less than 0.05). By comparison of the results obtained by these two techniques, it emerged that the ELISA test (using our preparation of submitochondrial particles) was not able to detect the antibody directed against the mitochondrial peptide of 52 kD, which thus seems to be different from the other specificities.

Differential growth inhibition of human diploid fibroblasts by 2-deoxyglucose and antimycin A with ageing in vitro

The relative growth inhibitory effects of 2-deoxyglucose and antimycin A were monitored at five stages during the life-span in vitro of human diploid fibroblasts. A marked age-dependent response was observed with 2-deoxyglucose but not with antimycin A. The results confirm an increase in the rate of glycolysis with ageing, which appears to be independent of cellular mitochondrial respiratory chain capacity. This may be associated with reduced utilization of the hexose monophosphate shunt and a consequent decline in the availability of ribose moieties for nucleic acid biosynthesis.

Inactivation of alpha-1-proteinase inhibitor in serum by stimulated human polymorphonuclear leucocytes. Evidence for a myeloperoxidase-dependent mechanism

Triggered polymorphonuclear leucocytes (PMNL) can decrease the elastase inhibitory capacity of serum by inactivating the main inhibitor of elastase alpha-1-proteinase inhibitor (alpha-1-PI). Maximal inactivation occurs with stimuli that release myeloperoxidase from PMNL along with hydrogen peroxide. Specific protection of alpha-1-PI function is obtained with antioxidants that interfere with this system. PMNL that are activated with phorbol myristate acetate release hydrogen peroxide but not myeloperoxidase, and only inactivate alpha-1-PI in the presence of exogenously-added PMNL-derived supernatants which contain this enzyme. Cell-free inactivation requires both active enzyme and hydrogen peroxide, and is greatest at pH 6.2, the pH optimum for myeloperoxidase-catalysed inactivation of alpha-1-PI. This data supports the notion that leucocyte myeloperoxidase may act to suppress the antiprotease screen afforded by alpha-1-PI by generating hypochlorous acid in the presence of chloride and respiratory burst-derived hydrogen peroxide, and in the microenvironment of lowered pH associated with degranulation. Pulmonary emphysema seems to be associated with an imbalance between elastase and its inhibitors at the lung surface. PMNL are likely to play an important role in the pathogenesis of emphysema since they contain both elastase, which can solubilize connective tissue elastin, and the constituents of an oxidative system which can inactivate the most important antielastase, alpha-1-PI.

Biologically-significant scavenging of the myeloperoxidase-derived oxidant hypochlorous acid by some anti-inflammatory drugs

Neutrophils contain the enzyme myeloperoxidase, which oxidizes Cl- ions into the powerful oxidant hypochlorous acid (HOCl). HOCl inactivates alpha 1-antiprotease, permitting uncontrolled protease activities. Most anti-inflammatory drugs tested are capable of reacting with HOCl, but the reactions seem insufficiently rapid under physiological conditions to protect alpha 1-antiprotease against inactivation by HOCl. However, rapid scavenging of HOCl might contribute to the anti-inflammatory effects of penicillamine, gold sodium thiomalate, phenylbutazone and primaquine.