[MR imaging of the knee joint plain, following intra-articular administration of gadolinium DTPA, saline and air]

Noninvasive MRI of the knee joint yields a great deal of information on soft parts (ligaments, capsule, free fluid, menisci, cartilage) and bones. The image is changed by intraarticular administration of air and of small quantities of fluids supply many signals, such as gadolinium DTPA solution. The results and possibilities of application are discussed.

[Possibilities of magnetic resonance tomography in cardiac diagnosis]

32 patients with different cardiac lesions underwent examinations by magnetic resonance imaging (MRI). In order to reduce moving artefacts measurements were carried out with ECG-triggering. It was possible to make visible precise anatomical details of the heart in cases of congenital diseases, aneurysms, myocardial infarction etc. Important advantages are contrasted with obvious disadvantages.

Evidence for the cell-surface localization of antigens cross-reacting with the "mitochondrial antibodies" of primary biliary cirrhosis

Studies with subfractions of Saccharomyces cerevisiae obtained by differential centrifugation showed only two primary biliary cirrhosis-specific antigens. These antigenic species were shown, using preabsorption studies, to have determinants cross-reactive with their mammalian counterpart. Distribution profiles of marker enzymes and primary biliary cirrhosis antigens between sucrose density gradient subcellular fractions of yeast showed that a relatively high concentration of primary biliary cirrhosis-specific antigens was associated with fractions containing plasma membranes, as well as those containing mitochondria. The possible cell-surface localization of the primary biliary cirrhosis antigens was further investigated using an indirect immunofluorescent technique on a number of different mammalian cells. Rat hepatoma cells, isolated rat hepatocytes and human polymorphonuclear leukocytes and lymphocytes stained positively with primary biliary cirrhosis sera, but not with normal sera or primary biliary cirrhosis sera preabsorbed with beef heart mitochondria. However, blood cells from primary biliary cirrhotic patients gave positive immunofluorescence in all tests, which is compatible with prior binding of the patients' own antimitochondrial antibodies to the surface of the cells.

Reaction pattern of mitochondrial antibodies of primary biliary cirrhosis (PBC) is species specific but not organ specific

The cross reactivity of a well-characterized PBC serum was studied with mitochondria from a number of sources. These studies were to establish the nonorgan, species specificity of the reaction of PBC sera. As well as confirming some previously reported data, we have strong evidence suggesting that, in spite of species differences in Mr of the major antigenic bands, all mitochondria contain a set of common cross-reactive epitopes. The multiplicity of antigenic bands seen for mitochondria from some sources are shown to arise, in part, as proteolytically derived artefacts of bands of higher Mr, retaining some antigenic reactivity.

The specificity of thiourea, dimethylthiourea and dimethyl sulphoxide as scavengers of hydroxyl radicals. Their protection of alpha 1-antiproteinase against inactivation by hypochlorous acid

Thiourea and dimethylthiourea are powerful scavengers of hydroxyl radicals (.OH), and dimethylthiourea has been used to test the involvement of .OH in several animal models of human disease. It is shown that both thiourea and dimethylthiourea are scavengers of HOCl, a powerful oxidant produced by neutrophil myeloperoxidase. Hence the ability of dimethylthiourea to protect against neutrophil-mediated tissue damage cannot be used as evidence for a role of .OH in causing such damage. Dimethyl sulphoxide also reacts with HOCl, but at a rate that is probably too low to be biologically significant at dimethyl sulphoxide concentrations up to 10 mM. Neither mannitol nor desferrioxamine, at the concentrations normally used in radical-generating systems, appears to react with HOCl.

The antioxidant action of human extracellular fluids. Effect of human serum and its protein components on the inactivation of alpha 1-antiproteinase by hypochlorous acid and by hydrogen peroxide

The elastase-inhibitory capacity of purified human alpha 1-antiproteinase is inactivated by low concentrations of the myeloperoxidase-derived oxidant hypochlorous acid, but much higher concentrations are required to inhibit the elastase-inhibitory capacity of serum samples. The protective effect of serum appears to be largely due to albumin. High concentrations of H2O2 also inactivate the elastase-inhibitory capacity of alpha 1-antiproteinase, by a mechanism not involving formation of hydroxyl radicals. Serum offers protection against H2O2 inactivation of alpha 1-antiproteinase. The relevance of these results to the tissue damage produced by activated phagocytes is discussed.

The occurrence and localization in trypanosomes and other endo-parasites of an antigen cross-reacting with mitochondrial antibodies of primary biliary cirrhosis

1. A mitochondrion-associated antigen to primary biliary cirrhosis (PBC) in man has been shown by solid-phase radioimmunoassay and immunoautoradiography to occur in several parasitic protozoa (Trypanosoma, Plasmodium and Eimeria spp.) and in the helminths Ascaridia galli and Nippostrongylus brasiliensis. 2. Stercorarian trypanosomes and T. brucei procyclics, with more highly-developed mitochondria, appear to contain more PBC antigen than the salivarian trypomastigote, in accordance with the known mitochondrial association of the antigen. 3. Trypanosoma lewisi and A. galli gave consistently high reactivity for PBC antigen, the antigen of the former being localized predominantly to the microsomal fraction.

Discrimination between M2 and M4 antimitochondrial antibodies in primary biliary cirrhosis

10 sera were studied from patients with primary biliary cirrhosis (PBC), that were anomalous in their reactivity against mitochondrial antigens as detected by Western blotting. They had low reactivity against the major, M2 reactive antigen (Mr for beef heart mitochondria, 74 Kd) but reacted against an antigen of Mr 52 Kd (species independent) which was apparently inaccessible in submitochondrial particles (SMP) on ELISA and which was not present in chloroform-released ATPase preparations. In all respects this differed from the characteristics of the M2 antigens and it is concluded that these sera are detecting predominantly the M4-reactive antigen.

Haemosiderin-like properties of free-radical-modified ferritin

Conjugated-Schiff's-base-type fluorescence was measured in iron-depleted samples and chloroform extracts of human spleen haemosiderin. Incubation of ferritin with liposomes and ascorbate led to the formation of compounds with similar fluorescence properties. Analysis of protein subunits by SDS/polyacrylamide-gel electrophoresis confirmed that ferritin was damaged in incubations with ascorbate. Since previous studies have shown that intact ferritin is resistant to proteolytic degradation, it is suggested that haemosiderin may be a product of oxidative reactions involving ferritin and lipid.

Tissue-specific and constitutive alpha-tubulin genes of Drosophila melanogaster code for structurally distinct proteins

We have determined the nucleotide sequences of all four Drosophila alpha-tubulin genes (alpha 1, alpha 2, alpha 3, and alpha 4). Two of the genes, alpha 1 and alpha 3, are constitutively expressed and code for proteins that are very similar to previously sequenced alpha-tubulins. They differ from each other by only two amino acid substitutions. These two genes also have blocks of homology between the noncoding leader regions of their transcription units. In contrast to these constitutive genes, the tissue-specific alpha 2 and alpha 4 genes code for tubulins with different structures. The alpha 2 mRNA is male-specific in adults and codes for a tubulin that differs from alpha 1 at 21 of the 450 residues. Six nonconservative substitutions are clustered within the 14 carboxyl-terminal amino acids, a region implicated in the regulation of microtubule assembly. The alpha 4 mRNA is maternal and is found only in ovarian nurse cells, eggs, and early embryos. It codes for the most highly divergent alpha-tubulin yet reported and differs from alpha 1 at 149 positions.

Demonstration of plasma-membrane adenosine diphosphatase activity in rat lung

The adenosine diphosphatase (ADPase) activity of rat lung has been investigated. Subcellular fractionation of lung tissue homogenates by sucrose density gradient centrifugation has shown the ADPase activity to be associated with the plasma membrane. ADPase was solubilised from the membranes and fractionated by ammonium sulphate precipitation to separate a specific, low-Km ADPase from non-specific alkaline phosphatase activity. The solubilised ADPase has a Km of 50 microM at pH 7.5 and appears to be distinct from ATPase.

Formation of hydroxyl radicals in the presence of ferritin and haemosiderin. Is haemosiderin formation a biological protective mechanism?

Horse spleen and human spleen ferritins increase the formation of hydroxyl radicals (OH) at both pH 4.5 and pH 7.4 in reaction mixtures containing ascorbic acid and H2O2. The generation of OH is inhibited by the chelator desferrioxamine. Human spleen haemosiderin also accelerates OH generation in identical reaction mixtures, but is far less effective (on a unit iron basis) than ferritin under all reaction conditions. It is proposed that conversion of ferritin into haemosiderin in iron overload is biologically advantageous in that it decreases the ability of iron to promote oxygen-radical reactions.

Carpal tunnel syndrome and acromegaly

50 patients with acromegaly and carpal tunnel syndrome have been examined electrophysiologically before and after transnasal operation of the pituitary adenoma. 32 of the 50 patients (64%) had symptoms of carpal tunnel syndrome. 13 of them had neurological deficits. 28 of the examined patients had pathological neurographical findings only. About 1 week post-operatively DL was decreased in 43%; in 10 out of 13 patients with neurological deficits DL decreased. GH was normalized in 80% and reduced to 5-10 micrograms/l in a further 10%. The investigation did not show whether the carpal tunnel syndrome only depended on a GH increase or on other factors also such as e.g., on the duration of symptoms or tissue changes. None of the patients had the transversal carpal ligament operated on. The coincidence between acromegaly and carpal tunnel syndrome was 64%. In 3 cases the carpal tunnel syndrome was the leading sign to the diagnosis of acromegaly.

Mitochondrial antibodies in primary biliary cirrhosis: species and nonspecies specific determinants of M2 antigen

Sera from patients with primary biliary cirrhosis reacted with four major bands in beef heart mitochondria and ATPase extract when analyzed by immunoblot after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These four immunologically reactive bands corresponded to protein bands with molecular weights of about (a) 80,000; (b) 63,000; (c) 56,000; and (d) 43,000 to 46,000. An additional immunoreactive band was found with some high-titered primary biliary cirrhosis sera at 36,000. No association with any ATPase subunits was found, except for band c which migrated between the alpha- and beta-subunit of ATPase. Most ATPase fractions did not contain this band c, indicating that M2 determinants, as defined by immunoblot, are not identical with any ATPase subunit. Species and nonspecies-specific determinants of M2 were identified using mitochondria from rat liver and human heart and liver. Antigenic bands a, c and d were nonspecies-specific. Band b and e occurred only in beef heart. An additional determinant at about 38,000 was detected using human heart and liver mitochondria. Primary biliary cirrhosis sera showed a typical reaction with two protein bands of Escherichia coli, one at about 85,000 to 90,000 and the other at 60,000. Antibodies against both determinants could be absorbed with submitochondrial particles of beef heart showing that E. coli shares cross-reacting determinants with mitochondria. Sera from 56 primary biliary cirrhosis patients were tested using beef heart mitochondria.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of iron in ferritin- and haemosiderin-mediated lipid peroxidation in liposomes

Ferritin and haemosiderin were shown, by the measurement of malondialdehyde production and loss of polyunsaturated fatty acids, to stimulate lipid peroxidation in liposomes. At pH 7.4 ascorbate was additionally required to achieve peroxidation; however, peroxidation occurred at pH 4.5 in the presence of iron-proteins alone. The damage was completely inhibited by the incorporation of chain-breaking antioxidants (alpha-tocopherol and butylated hydroxytoluene) into the liposomes. Metal chelators (desferrioxamine and EDTA) also completely inhibited lipid peroxidation. These and further results indicate that, at pH 4.5, even in the absence of a reducing agent, iron is released from haemosiderin and can mediate oxidative damage to a lipid membrane.

Correlation of oligomycin-sensitive ATPase activity in trypanosomes with their content of an antigen to primary biliary cirrhosis

The amounts of an antigen to primary biliary cirrhosis (PBC) which occur in subcellular fractions of Trypanosoma rhodesiense and T. lewisi correlate positively with the oligomycin-sensitive (OS) ATPase activity of these fractions. This result is consistent with the mitochondrial ATPase association of the antigen in mammalian and other cells. Higher levels of OS-ATPase and of PBC antigen in T. lewisi accord with a more extensive mitochondrial development in this species.

Detection of an antigen to primary biliary cirrhosis in wild type and petite mutant Saccharomyces cerevisiae

Antigens to primary biliary cirrhosis (PBC) appeared to be identical in wild type (rho+) and petite (rho o) mutant S.cerevisiae. As the latter mutants lack functional mitochondria, the PBC antigens, which are associated with mitochondrial ATPase in other cells, may be of nucleocytoplasmic origin.

Studies on the nature of adenosine diphosphatase activity from rat liver mitochondria

Adenosine diphosphatase (ADPase) activity was studied in rat liver with [beta-32P]ADP as a substrate. Mitochondria and outer mitochondrial membrane fractions were isolated and assayed for ADPase and various marker enzymes. ADPase activity was strikingly reduced when the outer membranes were removed from the mitochondria whether by digitonin treatment or osmotic shock. Addition of the inter-membrane space subfraction to the purified outer membranes resulted in enhanced ADPase activity. Addition of the inter-mitochondrial membrane enzyme adenylate kinase to outer membranes also produced a large stimulation of activity. The ADPase activity could also be reconstituted in vitro with adenylate kinase and either mitoplast ATPase or ouabain-sensitive (Na+ + K+ + Mg2+)-ATPase. Chloroform-released ATPase, however, was not capable of producing an ADPase activity when combined with adenylate kinase. Gel permeation chromatography of Triton-solubilised outer mitochondrial membranes was unable to resolve ADPase activity from contaminating ATPase. These results suggest that the majority of ADPase activity in rat liver mitochondria consists of the coupled activity of adenylate kinase and ATPase.

Comparison of effects of inhibitors on adenosine triphosphatase and adenosine diphosphatase activities in rat-liver mitochondria

Adenosine diphosphatase (ADPase) activity and ATPase activity were assayed in rat liver mitochondria and outer mitochondrial membrane preparations with [beta-32P]ADP and [gamma-32P]ATP as substrates. Inhibition studies were performed with the mitochondrial ATPase inhibitor oligomycin and the adenine nucleotide transport inhibitor, carboxyatractyloside. Kinetic studies were also performed with the nucleotide thiophosphate analogs adenosine 5'-O-thiophosphate, adenosine 5'-O-(2-thiodiphosphate) and adenosine 5'-O-(3-thiotriphosphate) which can act as inhibitors of phosphohydrolases. It is concluded that part of the apparent ADPase activity of intact mitochondria is mediated via ATPase, presumably in conjunction with adenylate kinase. In addition the outer mitochondrial membrane appears to show a distinct ADPase not attributable to contamination by inner membrane ATPase.

26-hydroxycholesterol: regulation of hydroxymethylglutaryl-CoA reductase activity in Chinese hamster ovary cell culture

The effect of 26-hydroxycholesterol and other intermediates in bile acid synthesis on HMG-CoA reductase activity was studied in Chinese hamster ovary (CHO) cell culture. Incubation of CHO cells for 5 hr in 0.25 microM 26-hydroxycholesterol caused a 40% inhibition of HMG-CoA reductase activity. All other intermediates tested including 3 beta-hydroxy-5-cholenoic acid and cholest-5-ene-3 beta,7 alpha,26-triol, oxidation products of 26-hydroxycholesterol, had little or no inhibitory effect. It is proposed that 26-hydroxycholesterol has a selective biological role in the regulation of cholesterol synthesis.

Antimitochondrial antibodies (AMA) in primary biliary cirrhosis. I. Separation of the PBC antigen activity from mitochondrial ATPase activity

Antimitochondrial antibodies are found in a variety of autoimmune liver diseases, particularly primary biliary cirrhosis. The antigen against which these antibodies are directed is localized on the inner mitochondrial membrane. Earlier work suggested that this antigen was associated with the mitochondrial ATPase. However, we have succeeded in separating the enzyme activity from the antigenic activity using gel filtration and ion-exchange chromatography. Furthermore, the antigenic activity is not affected by modulators of ATPase enzymatic activity like aurovertin or oligomycin. The antigenic activity is, however, very susceptible to reagents which block thiol groups. The mitochondrial antigen, in contrast to the ATPase enzyme, is found in high amounts in brown fat mitochondria. Identification of this antigen may help to explain why specific antimitochondrial antibodies arise in the sera of patients with primary biliary cirrhosis.