Medizin - Open Access LMU - Teil 10/22

HYPERGLYCAEMIA impairs recovery from transient cerebral ischaemia: the importance of tissue acidification for this phenomenon has not been clarified in detail. We investigated this issue in a less complex in vitro preparation of isolated rat dorsal spinal roots exposed for 30 min to hyperglycaemic hypoxia. Peak height of compound action potentials recovered minimally in 5 mM bicarbonate. However, recovery was greatly improved by addition of the weak base trimethylamine during re-oxygenation. Addition of the weak acid propionate had no such effect. Cytoplasmic alkalinization improved recovery in a brief time window only: application of trimethylamine after 15 min of re-oxygenation was without beneficial effect. These data emphasize the importance of cytoplasmic acidification for neurophysiological recovery from hyper-glycaemic hypoxia during the initial period of re-oxygenation.

1. Electrotonic responses to 150 ms current pulses were recorded from isolated rat dorsal roots incubated for at least 3 h with either normal (5 mM) or high (25 mM) D-glucose solutions, and with either normal (25 mM) or low (5 mM) bicarbonate concentrations. 2. On replacement of O2 by N2 for 50 min, all the roots depolarized, but the changes in electrotonus differed systematically. With normal glucose, the depolarization was accompanied by an increase in input conductance. In contrast, for the hyperglycaemic roots the depolarization was slower and accompanied by a fall in input conductance which was exacerbated in low bicarbonate concentrations. 3. The changes induced by hyperglycaemic hypoxia in low bicarbonate could be mimicked by exposure of the roots either to 100% CO2 or to a combination of 3 mM tetraethylammonium chloride and 3 mM 4-aminopyridine, to block both fast and slow potassium channels. 4. These results indicate that the primary mechanism of hypoxic depolarization of these sensory axons is altered by hyperglycaemia. In normoglycaemia, the changes in electrotonus are consistent with an increase in axonal potassium conductance. The block of potassium channels seen in hyperglycaemic hypoxia is attributed to intra-axonal acidification by anaerobic glycolysis and may contribute to the pathogenesis of diabetic neuropathy.

We have compared the expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) genes in various human tissues using a quantitative polymerase chain reaction technique. Tissues of three human subjects, obtained at autopsy, were analyzed. BNP transcripts could be detected in the central nervous system, lung, thyroid, adrenal, kidney, spleen, small intestine, ovary, uterus, and striated muscle. ANP transcripts could also be demonstrated in various human extracardiac tissues including several endocrine organs. In all peripheral tissues, the level of both natriuretic peptide transcripts was approximately 1-2 orders of magnitude lower than in cardiac ventricular tissues. This distribution is in marked contrast to the much lower level of ANP and BNP transcripts present in extracardiac rat tissues (generally less than 1/1000 of ventricles). These data suggest differential expression of the two natriuretic peptide genes in cardiac and extracardiac tissues in man. Furthermore, the presence of local synthesis of ANP and BNP in various peripheral organs suggests paracrine and/or autocrine function of these natriuretic peptides.

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/5987/1/5987.pdf Gerbes, Alexander L.; Paumgartner, Gustav; Witthaut, Rochus; Bilzer, Manfred

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/5988/1/Gerbes_ALexander_5988.pdf Blendis, Laurence; Peter Liu, Liu; Wong, Florence; Gerbes, Alexander L.; Sørensen, Thorkild I. A.; Møgelvang, Jens; Stokholm, K. Heine; Ring-Larsen, Helmer; Bendtsen, Flemming; Møller, Søren; Henriksen, Jens H. ddc:610,

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/5989/1/Gerbes_Alexander_5989.pdf Schölmerich, J.; Gerbes, Alexander L. ddc:610, Medizin

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/5996/1/5996.pdf Jüngst, Dieter; Gerbes, Alexander L.

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/6073/1/6073.pdf Paumgartner, Gustav; Gerbes, Alexander L. ddc:610, Medizin 0

Since the 64kDa-protein glutamic acid decarboxylase (GAD) is one of the major autoantigens in T-cell mediated Type 1 diabetes, its relevance as a T-cell antigen needs to be clarified. After isolation of splenic T-cells from non-obese diabetic (NOD) mice, a useful model for human Type 1 diabetes, we found that these T-cells proliferate spontaneously when incubated with human GAD65, but only marginally after incubation with GAD67, both recombinated in the baculovirus system. No effect was observed with non-diabetic NOD mice or with T-cells from H-2 identical NON-NOD-H-2g7 control mice. It has been published previously that NOD mice develop autoantibodies against a 64kDa protein detected with mouse beta cells. In immunoprecipitation experiments with sera from the same NOD mice and 33S-methionine-labelled GAD, no autoantibody binding could be detected. We conclude firstly that GAD65 is an important T-cell antigen which is relevant early in the development of Type 1 diabetes and secondly that there is an antigenic epitope in the human GAD65 molecule recognized by NOD T-cells, but not by NOD autoantibodies precipitating conformational epitopes. Our results therefore provide further evidence that GAD65 is a T-cell antigen in NOD mice, being possibly also involved in very early processes leading to the development of human Type 1 diabetes.

By using an immunoprecipitation assay, we analysed reactivity of autoantibodies to human recombinant GAD65 and GAD67 in sera from patients with autoimmune polyendocrine syndrome Type II (APS II) with and without Type 1 (insulin-dependent) diabetes mellitus (IDDM) compared to patients with organ-specific autoimmunity. Overall antibodies to GAD65 were correlated with IDDM in all study groups, whereas GAD67 antibodies were associated with IDDM when APS II coexists. Antibodies to GAD65 and GAD67 were detected in 13 (44.8%) and 7 (24.1%) out of 29 APS II patients with IDDM, but in only 4 (13.8%) and 2 (6.9%) out of 29 APS II patients without IDDM, respectively (p < 0.05). In short-standing IDDM (< 1 year), antibodies to GAD67 were significantly more frequent in patients with APS II (5 of 9 [55.6%] subjects) compared to matched diabetic patients without coexisting polyendocrinopathy (1 of 18 [5.6%] subjects) (p < 0.02). The levels of GAD65 (142 ± 90 AU) and GAD67 antibodies (178 ± 95 AU) were significantly higher in patients with polyglandular disease than in patients with isolated IDDM (91 ± 85 AU and 93 ± 57 AU) (p < 0.02). Interestingly, all 11 GAD67 antibody positive subjects also had GAD65 antibodies (p < 0.0001), and in 10 of 11 anti-GAD67 positive sera the GAD67 antibodies could be blocked by either GAD67 or GAD65, suggesting the presence of cross-reactive autoantibodies. No correlation was observed between GAD antibodies and age, sex or any particular associated autoimmune disease, besides IDDM. GAD antibodies were present in only 1 of 6 (16.7%) patients with APS Type I, in 1 of 26 (3.9%) patients with autoimmune thyroid disease but in none of the patients with Addison's disease (n = 16), pernicious anaemia (n = 7) or normal controls (n = 50). Our data suggest distinct antibody specificities reactive to GAD isoforms in APS II and IDDM, which might reflect different mechanisms of autoimmune response in IDDM with coexisting autoimmune polyendocrine autoimmunity.

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/6088/1/6088.pdf Paumgartner, Gustav; Gerbes, Alexander L. ddc:610, Medizin

1. Adult rats and rats with a postnatal age of 3-29 days (PN 3-29) were used for the preparation of in vitro slices of the frontal neocortex. Epileptiform activity was induced by bath application of the gamma-aminobutyric acid-A (GABAA) receptor antagonists bicuculline or picrotoxin. 2. The voltage-sensitive dye RH 414 and a laser scanning microscope were used for multiple-site optical recordings of membrane potential changes associated with epileptiform activity. Optical signals were compared with simultaneously measured extra-cellular field potentials. 3. Optical signals could be reliably recorded for the duration of the experiments (2-4 h). Extracellular recordings of convulsant-induced paroxysmal depolarizing shifts (PDSs) in slices stained with RH 414 were comparable with those obtained in unstained slices. Changes in dye signals in response to reductions in extracellular calcium, addition of tetrodotoxin (TTX), or application of excitatory amino acid receptor antagonists indicate that the fluorescence changes correlate well with established electrophysiological measures of epileptiform activity. 4. In slices from adult animals, dye signals were observed at all recording sites. The response with the shortest latency occurred invariably at the site of stimulation, and activity spread rapidly in both vertical and horizontal directions. Spread was significantly faster in the vertical than in the horizontal direction. 5. Epileptiform activity was absent or only weakly expressed in slices from PN 3-9 animals. Activity was detectable predominantly in upper cortical layers. 6. Dye signals were observed at all measurement points in slices from PN 10-19 animals. In this age group, peak amplitude increased with spread of activity from lower to upper cortical layers. There was no significant difference between the speed of propagation in the vertical and in the horizontal directions. Spontaneous epileptiform activity occurred at a high rate in the PN 10-19 age group, and signals associated with spontaneous epileptiform events were largest in upper layers. 7. In the PN 10-19 age group, optical signals were characterized by the repetitive occurrence of PDS discharges superimposed on a sustained response. The amplitude of the sustained response decreased with increasing distance from the site of stimulation. Analysis of the latencies revealed that the superimposed PDS-like events were generated at multiple sites within the scanning area. Amplitude and rate of rise were largest in slices from PN 10-19 animals. These values declined with ongoing development.

Stimulus-evoked dopamine overflow in rat neostriatal slices was determined using fast cyclic voltammetry. The dopamine efflux induced by intrastriatal stimulation increased with stimulus intensity and was found to be enhanced by more than 100% upon application of the dopamine uptake inhibitor nomifensine. The acetylcholine esterase inhibitor eserine concentration-dependently and reversibly depressed stimulus-induced dopamine overflow. This effect was mediated by both, muscarinic and nicotinic cholinergic receptors: the action of eserine was mimicked by cholinergic agonists (muscarine and nicotine) and the effects of these agonists were blocked by muscarinic and nicotinic antagonists (atropine and dihydro-β-erythroidine). These experiments suggest that endogenous acetylcholine exerts an inhibitory control on stimulus-evoked (i.e. phasic) dopamine overflow in vitro by affecting striatal dopaminergic nerve terminals.

The political change in the former Soviet Union and its sphere of influence has brought into the open information on various situations involving the radiation exposure of large populations, and has thus widened the field of radioepidemiological investigations that need to be performed. Three issues are considered. The consequences of the Chernobyl accident are still largely unresolved, and the hopes for radioepidemiological investigations have been gravely disappointed due to the lack of coordinated efforts. The steep increase of childhood thyroid carcinoma rates in Belarus is the only observed late effect so far; but even in the face of this alarming situation there is little readiness to accept help with regards to medical treatment and to scientific investigations. The attempts to block all information after the reactor accident in the former Soviet Union must be seen against the background of earlier occurrences that were successfully hidden for decades, and a particularly grave issue was the large scale contaminations in the Southern Urals of the River Techna and adjacent villages. An epidemiological study on the affected population has led to first results; it may develop into a major body of knowledge on radiation risks from protracted exposures. A third broad task in the years to come will be the analysis of the health effects in the underground miners of the Wismut AG, the former Soviet-German uranium mining enterprise. Exposure data and health information on several 100,000 miners will need to be analysed, and this may further the knowledge of the effects of radon exposures.

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/6145/1/6145.pdf Gerbes, Alexander L. ddc:610, Medizin

The distribution of imparted energy deposited at distance from the axis of a proton beam, i.e. the lateral distribution of absorbed dose, is determined by measurement of the light emission in nitrogen at the wavelengths of 391.4 nm and 337.1 nm in single photon counting technique. Results for the proton energies 4, 8 and 11 MeV are given.

Microdosimetry can be an important tool in fundamental radiobiology towards an improved understanding of the primary mechanisms of radiation action. In addition, its applications in radiation protection and in clinical radiology have been of increasing importance. The variance-covariance method relates to such applications; it permits the determination of the dose averaged microdosimetric parameters in radiation fields of varying intensity. Measurements with the variance-covariance method are here reported for therapy electron beams with acceleration voltages from 5 to 20 MV. The experimental results are compared with Monte-Carlo simulations.

The estimates of lung cancer risk due to the exposure to radon decay products are based on different data sets from underground mining and on different mathematical models that are used to fit the data. Diagrams of the excess relative rate per 100 working level months in its dependence on age at exposure and age attained are shown to be a useful tool to elucidate the influence that is due to the choice of the model, and to assess the differences between the data from the major western cohorts and those from the Czech uranium miners. It is seen that the influence of the choice of the model is minor compared to the difference between the data sets. The results are used to derive attributable lifetime risks and probabilities of causation for lung cancer following radon progeny exposures.

A procedure for the quantification of double-strand breaks in yeast is presented that utilizes pulsed field gel electrophoresis (PFGE) and a comparison of the observed DNA mass distribution in the gel lanes with calculated distributions. Calculation of profiles is performed as follows. If double-strand breaks are produced by sparsely ionizing radiation, one can assume that they are distributed randomly in the genome, and the resulting DNA mass distribution in molecular length can be predicted by means of a random breakage model. The input data for the computation of molecular length profiles are the breakage frequency per unit length, , as adjustable parameter, and the molecular lengths of the intact chromosomes. The obtained DNA mass distributions in molecular length must then be transformed into distributions of DNA mass in migration distance. This requires a calibration of molecular length vs. migration distance that is specific for the gel lane in question. The computed profiles are then folded with a Lorentz distribution with adjusted spread parameter to account for and broadening. The DNA profiles are calculated for different breakage frequencies and for different values of , and the parameters resulting in the best fit of the calculated to the observed profile are determined.

Radially restricted linear energy transfer (LET) is a basic physical parameter relevant to radiation biology and radiation protection. In this report a convenient method is presented for the analytical computation of this quantity without the need for complicated simulation. The method uses the energy-re-stricted LETL, as recently redefined in a 1993 ICRU draft document and supplements it by a relatively simple term that represents the energy of fast rays lost within distancer from the track core. The method provides a better fit than other models and is valid over the entire range of radial distance from track center to the maximum radial distance traveled by the most energetic secondary electrons.L r computed by this approach differs only a few percent from the values Contribution to the international symposium on heavy ions research: space, radiation protection and therapy, 21–24 March 1994, Sophia-Antipolis, France

A method for testing and calibrating tissue equivalent proportional counters with37Ar is described.37Ar is produced by exposure of argon in its normal isotope composition to thermal neutrons. It is shown that - up to volume ratios of 0.01 of argon to the tissue equivalent gas - there is no appreciable effect of the argon admixture on the function of the proportional counter. Conventional calibration methods with characteristic x-rays or with -particles require modifications of the detectors, and they test only small sub-volumes in the counters. In contrast, argon permits calibrations and tests of the resolution that are representative for the entire counter volume and that do not require changes in detector construction. The method is equally applicable to multi-element proportional counters; it is here exemplified by its application to a long cylindrical counter of simplified design that is part of such a multi-element configuration.

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/6163/2/6163.pdf Stefani, F.-H.; Spiess, H.; Kellerer, Albrecht M.; Wegener, A.; Roos, H.; Egner, P.; Nekolla, E.; Scharff, J.-P. ddc:610, Medizin

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/6164/1/6164.pdf Griebel, J.; Kellerer, Albrecht M. ddc:610, Medizin 0

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/6178/1/6178.pdf Lehnert, Peter; Karbach, U.; Veith, K.; Hundegger, K.; Riepl, Rudolf L.

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/6181/1/6181.pdf Gerbes, Alexander L. ddc:610, Medizin

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/6329/1/6329.pdf Berghaus, Alexander; Kippenhahn, K.; Jovanovic, S.

Sat, 1 Jan 1994 12:00:00 +0100 https://epub.ub.uni-muenchen.de/6330/1/6330.pdf Berghaus, Alexander

Wed, 1 Dec 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7854/1/7854.pdf Benedetto, K. P.; Steinlechner, M.; Müller-Gerbl, Magdalena; Putz, Reinhard; Eckstein, Felix

Wed, 1 Dec 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/8185/1/Bogner_Johannes_8185.pdf Goebel, Frank-Detlef; Einhäupl, Karl Max; Hammel, Gertrud; Bogner, Johannes R.; Sadri, Ifna; Tatsch, Klaus; Schielke, Eva; Geier, Stephan A.

Mon, 15 Nov 1993 12:00:00 +0100 http://www.jbc.org/cgi/content/abstract/268/32/23751 https://epub.ub.uni-muenchen.de/7670/1/Neupert_Walter_7670.pdf Neupert, Walter; Stuart, Rosemary A.; Cyr, Douglas M.

As a basis towards a better understanding of the role of the pregnancy-specific glycoprotein (PSG) family in the maintenance of pregnancy, detailed investigations are described on the expression of a recently identified rat PSG gene (rnCGM1) at the mRNA and protein levels. Using specific oligonucleotide primers, rnCGM1 transcripts were identified after reverse transcription, polymerase chain reaction, and hybridization with a radiolabelled, internal oligonucleotide. Transcripts were only found in significant amounts in placenta. In situ hybridization visualized rnCGM1 transcripts at day 14 post coitum (p.c.), in secondary trophoblast giant cells and in the spongiotrophoblast. Only those secondary giant cells lining the maternal decidua were positive. In contrast, primary giant cells did not contain rnCGM1 mRNA. At day 18 p.c., rnCGM1. transcripts were almost exclusively detectable in the spongiotrophoblast. No rnCGM1 transcripts were found in rat embryos of these two developmental stages. Rabbit antisera were generated against the amino-terminal immunoglobulin variable-like domain and against a synthetic peptide containing the last 13 carboxy-terminal amino acids of rnCGM1. Bothe antisera recognized a 124 kDa protein in day 18 rat placental extracts as identified by Western blot analysis. The anti-peptide antiserum recognized a 116 kDa protein in the serum of a 14 day p.c. pregnant rat that is absent from the sera of non-pregnant females. Taken together, these results confirm exclusive expression of rnCGM1 in the rat trophoblast, but unlike human PSG, negligible or no expression is found in other organs, such as fetal liver or salivary glands, indicating a more specialized function of rnCGM1. Its spatiotemporal expression pattern is conducive with a potential role of PSG in protecting the fetus against the maternal immune system and/or in regulating the invasive growth of trophoblast cells.

Fri, 15 Oct 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7087/1/7087.pdf Spengel, F. A.; Küffer, G.; Rademacher, Antje

Carcinoembryonic antigen (CEA) is a tumor marker that belongs to a family of closely related molecules with variable expression patterns. We have developed sets of oligonucleotide primers for the specific amplification of transcripts from individual CEA-family members using the reverse transcriptase/ polymerase chain reaction (RT/PCR). Specific primer sets were designed for CEA, non-specific cross-reacting antigen (NCA), biliary glycoprotein (BGP), carcinoembryonic antigen gene-family members 1, 6 and 7 (CGMI, CGM6 and CGM7), and one set for all pregnancy-specific glycoprotein (PSG) transcripts. Primers were first tested for their specificity against individual cDNA clones and product-hybridization with internal, transcript-specific oligonucleotides. Total RNA from 12 brain and 63 gynecological tumors were then tested for expression of CEA-related transcripts. None were found in tumors located in the brain, including various mesenchymal and neuro-epithelial tumors. CEA and NCA transcripts were, however, present in an adenocarcinoma located in the nasal sinuses. In ovarian mucinous adenocarcinomas, we always found co-expression of CEA and NCA transcripts, and occasionally BGP mRNA. CEA-related transcripts were also found in some serous, endometrioid and clear-cell ovarian carcinomas. CEA, NCA and BGP transcripts were present in endometrial carcinomas of the uterus and cervical carcinomas, whereas uterine leiomyomas were completely negative. No transcripts were found from CGM 1, CGM6, CGM7 or from PSG genes in any of the tumors tested. The PCR data were compared with immunohistochemical investigations of ovarian tumors at the protein level using CEA (26/3/13)-, NCA-50/90 (9A6FR) and NCA-95 (80H3)-specific monoclonal antibodies.

Wed, 1 Sep 1993 12:00:00 +0100 http://www.springerlink.com/content/q33519x33270104m/?p=815bffe164cd4f0f86fc8f8d6f9ac2ea&pi=0 https://epub.ub.uni-muenchen.de/7641/1/Neupert_Walter_7641.pdf Neupert, Walter; Pfanner, Nikolaus; Becker, Karin; Kiebler, Michael ddc:610, Medizin

Wed, 1 Sep 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7871/1/Putz_Reinhard_7871.pdf Putz, Reinhard ddc:610, Medizin

Fri, 13 Aug 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7640/1/Neupert_Walter_7640.pdf Neupert, Walter; Pfanner, Nikolaus; Klei, Ida J. van der; Schneider, Helmut; Keil, Petra; Kiebler, Michael ddc:610, Medizin

Cytochrome b2 contains 2-fold targeting information: an amino-terminal signal for targeting to the mitochondrial matrix, followed by a second cleavable sorting signal that functions in directing the precursor into the mitochondrial intermembrane space. The role of the second sorting sequence was analyzed by replacing one, two or all of the three positively charged amino acid residues which are present at the amino-terminal side of the hydrophobic core by uncharged residues or an acidic residue. With a number of these mutant precursor proteins, processing to the mature form was reduced or completely abolished and at the same time targeting to the matrix space occurred. The accumulation in the matrix depended on a high level of intramitochondrial ATP. At low levels of matrix ATP, the mutant proteins were sorted into the intermembrane space like the wild-type precursors. The results: (i) suggest the existence of one or more matrix components that specifically recognize the second sorting signal and thereby trigger the translocation into the intermembrane space; (ii) indicate that the mutant signals have reduced ability to interact with the recognition component(s) and then embark on the default pathway into the matrix by interacting with mitochondrial hsp70 in conjunction with matrix ATP; (iii) strongly argue against a mechanism by which the hydrophobic segment of the sorting sequence stops translocation in the hydrophobic phase of the inner membrane.

Nuclear-encoded proteins destined for mitochondria must cross the outer or both outer and inner membranes to reach their final sub- mitochondrial locations. While the inner membrane can translocate preproteins by itself, it is not known whether the outer membrane also contains an endogenous protein translocation activity which can function independently of the inner membrane. To selectively study the protein transport into and across the outer membrane of Neurospora crassa mitochondria, outer membrane vesicles were isolated which were sealed, in a right-side-out orientation, and virtually free of inner membranes. The vesicles were functional in the insertion and assembly of various outer membrane proteins such as porin, MOM19, and MOM22. Like with intact mitochondria, import into isolated outer membranes was dependent on protease-sensitive surface receptors and led to correct folding and membrane integration. The vesicles were also capable of importing a peripheral component of the inner membrane, cytochrome c heme lyase (CCHL), in a receptor-dependent fashion. Thus, the protein translocation machinery of the outer mitochondrial membrane can function as an independent entity which recognizes, inserts, and translocates mitochondrial preproteins of the outer membrane and the intermembrane space. In contrast, proteins which have to be translocated into or across the inner membrane were only specifically bound to the vesicles, but not imported. This suggests that transport of such proteins involves the participation of components of the intermembrane space and/or the inner membrane, and that in these cases the outer membrane translocation machinery has to act in concert with that of the inner membrane.

The binding of bacteria or bacterial products to host proteins of tissue extracellular matrix may be a mechanism of tissue adherence. We investigated interactions of the plasmid-encoded outer membrane protein YadA, which confers pathogenic functions on enteropathogenic yersiniae, with fibronectin. Attachment of YadA-positive and YadA-negative recombinant Yersinia enterocolitica strains to cartilage-derived human cellular fibronectin and human plasma fibronectin in the solid phase revealed that YadA mediates binding of yersiniae to cellular fibronectin in a saturable, concentration-dependent manner. The interaction could be inhibited by an anti-YadA-specific anti-serum. An anti-beta 1-integrin antibody and the synthetic peptide G-R-G-D-S-P, representing the binding site for alpha 5 beta 1-integrin on fibronectin, did not block attachment of YadA-positive yersiniae to cellular fibronectin, indicating a binding site for YadA on cellular fibronectin independent of the R-G-D-S-containing site. By contrast, YadA failed to mediate binding to plasma fibronectin immobilized on nitrocellulose or plastic surfaces. These observations provide evidence for the hypothesis that the binding region for YadA in cellular fibronectin is not present in plasma fibronectin. This study is the first report on differential binding of bacteria to splicing variants of fibronectin. Further experiments might answer the question whether binding of YadA to cellular fibronectin contributes to the pathogenesis of yersiniae, both to the initial adhesion of the bacteria to the matrices of the host and to the arthritogenic potential of enteropathogenic yersiniae.

The protein translocation machineries of the outer and inner mitochondrial membranes usually act in concert during translocation of matrix and inner membrane proteins. We considered whether the two machineries can function independently of each other in a sequential reaction. Fusion proteins (pF-CCHL) were constructed which contained dual targeting information, one for the intermembrane space present in cytochrome c heme lyase (CCHL) and the other for the matrix space contained in the signal sequence of the precursor of F1-ATPase beta-subunit (pF1 beta). In the absence of a membrane potential, delta psi, the fusion proteins moved into the intermembrane space using the CCHL pathway. In contrast, in the presence of delta psi they followed the pF1 beta pathway and eventually were translocated into the matrix. The fusion protein pF51-CCHL containing 51 amino acids of pF1 beta, once transported into the intermembrane space in the absence of a membrane potential, could be further chased into the matrix upon re-establishing delta psi. The sequential and independent movement of the fusion protein across the two membranes demonstrates that the translocation machineries act as distinct entities. Our results support a model in which the two translocation machineries can function independently of each other, but generally interact in a dynamic fashion to achieve simultaneous translocation across both membranes. In addition, the results provide information about the targeting sequences within CCHL. The protein does not contain a signal for retention in the intermembrane space; rather, it lacks matrix targeting information, and therefore is unable to undergo delta psi-dependent interaction with the protein translocation apparatus in the inner membrane.

Thu, 1 Apr 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/9514/1/stief_christian_9514.pdf Tanagho, Emil A.; Lue, Tom F.; Wetterauer, Ulrich; Bosch, Ruud J. L. H.; Bénard, Francois; Stief, Christian Georg ddc:610, Medizin

Mon, 29 Mar 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7632/1/Neupert_Walter_7632.pdf Pfanner, Nikolaus; Neupert, Walter ddc:610, Medizin

The structure of the rat ciliary neurotrophic factor (CNTF) gene and the regulation of CNTF mRNA levels in cultured glial cells were investigated. The rat mRNA is encoded by a simple two-exon transcription unit. Sequence analysis of the region upstream of the transcription start-site did not reveal a typical TATA-box consensus sequence. Low levels of CNTF mRNA were detected in cultured Schwann cells, and CNTF mRNA was not increased by a variety of treatments. Three-week-old astrocyte-enriched cell cultures from new-born rat brain contained easily detectable CNTF mRNA. In astrocyte-enriched cultures, upregulation of CNTF mRNA levels was observed after treatment with IFN-. CNTF mRNA levels were down-regulated in these cells by treatments that elevate intracellular cyclic AMP and by members of the fibroblast growth factor (FGF) family. The implications of these results for potential in vivo functions of CNTF are discussed

It has been suggested that the distribution of the subchondral bone density may be regarded as the expression of the long-term effective stress in a joint, and previous results indicate the regularity of the distribution of subchondral bone density as a function of the passing demands made upon a joint. Computed tomography-osteoabsorptiometry has been developed to visualize the area distribution of subchondral mineralization in the major joints in vivo. The purpose of this study was to display the distribution of subchondral bone density in the acetabular cup of patients of different ages. Computer tomography data files of hip joints of 27 patients (18–89 years) were used. Density ranges, image analysis, and area presentation of the distribution of subchondral mineralization are presented. The maximal subchondral mineralization in young persons is found both in the ventral and dorsal part of the acetabular roof. In older people, however, the densest areas are most often found at the zenith of the acetabulum. These morphological results could be well explained by the experimental results of other authors who found a joint incongruity in young persons with contact areas in the ventral and dorsal part of the acetabulum. With advancing age a decrease in incongruence is found, leading to an increased stress in the dome, i.e. in the area where degenerative changes are often found.

Activation of the contact phase of coagulation has been implicated in the pathogenesis of septic shock. We wanted to determine if inhibition of plasma kallikrein can prevent arterial hypotension and liberation of kinins from kininogen, induced by an infusion of bacterial lipopolysaccharide (LPS) in anesthetized, ventilated 20-kg pigs. The LPS was given IV in a dose of 5 [mu]g/kg/h for 8 hours. The plasma kallikrein inhibitor aprotinin, 537 [mu]mol, was given IV during 8 hours, resulting in plasma levels above 10 [mu]mol/L. Ten animals (SA) received LPS and aprotinin and ten randomized controls (SC) received LPS and saline. Kinin-containing kininogen was determined on the basis of the amount of kinin releasable in plasma samples by incubation with trypsin. Kininogen decreased to 58% +/- 4% of the baseline value without any difference between groups. This may indicate participation of other processes than degradation by plasma kallikrein in the decrease of kininogen. Arterial blood pressure was higher at 7 hours in the SA animals than in the SC group (101% +/- 11% vs. 68% +/- 8%; mean +/- SEM; p = 0.026). Fibrin monomer and C3adesArg plasma levels were attenuated by aprotinin treatment. These findings underscore the important role of the contact system in LPS shock.

Objectives: To determine the serum concentrations of procollagen type in peptide in severely injured patients with different outcomes and to evaluate the relationship between serum procollagen type III peptide concentrations, sources of increased posttraumatic fibrotic activity (wounds, lung, liver, kidney), and decreased elimination of procollagen type III peptide (liver). Design: Prospective study. Setting: Surgical ICU, university hospital. Patients: Fifty-seven patients (mean injury severity score: 38.5 points, range 13 to 75 points), between 16 and 70 yrs of age, treated in our institution within 6 hrs after the accident. Measurements: Serial measurements were started on admission and continued on a 6-hr basis. After 48 hrs, the monitoring interval was extended to 24 hrs until recovery (but at least until day 14) or death. At each point of evaluation, pulmonary and circulatory function parameters and chest radiographs (once a day) were evaluated, the results were recorded, and blood samples were drawn to determine procollagen type III peptide, total bilirubin, creatinine, [gamma]-glutamyl transferase, polymorphonuclear elastase, and other parameters. Statistic evaluation was done with the Wilcoxon test, Spearman rank correlation, and a multiple regression model. Results: Mean procollagen type m peptide serum concentrations (+/- sd) were significantly different in patients who died (8.0 +/- 3.8 U/mL) compared with those patients who survived with organ failure (2.7 +/- 1.3 U/mL) or without complications (1.4 +/- 0.5 U/mL), respectively. Significant correlations of procollagen type HI peptide concentrations with the serum bilirubin concentrations (r = .7), days with need of mechanical ventilation (r = .64), Pao2/Fio2 ratio (r = -.6), polymorphonuclear elastase (r = .6), serum creatinine concentrations (r = .55), and injury severity score (r = .33) were observed. There was a tendency toward higher serum procollagen type III peptide concentrations in patients with severe skeletal injuries. Conclusions: Serum procollagen type III peptide concentrations in severely injured patients may be considerably increased in correlation with injury severity and outcome. Procollagen type III peptide serum concentrations seem to reflect the sum of increased collagen formation from wound healing and fibrogenesis of mediator-related organ damage (especially lung) and decreased procollagen type HI peptide excretion due to impaired liver function. Further data are necessary to evaluate the role of hepatic elimination in these patients.

Fri, 15 Jan 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/8828/1/kinetic_and_structural_analysis_of_the_mg2plus-binding_site_8828.pdf Wittinghofer, A.; Goody, R. S.; Borasio, Gian Domenico; Vetter, I.; Schlichting, I.; Rensland, H.; John, J.

Der Artikel befindet sich unter "Kurze wissenschaftliche Mitteilungen", ein anderes Inhaltsverzeichnis gibt es nicht.

Fri, 1 Jan 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/9068/1/9068.pdf Messmer, Konrad; Habazettl, H.; Zwißler, Bernhard; Welte, M.

Fri, 1 Jan 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/9076/1/9076.pdf Kellerer, Albrecht M.; Roos, H.; Egner, P.

The nominal risk coefficients for radiation induced cancer are largely based on the follow-up of the mortality from solid cancers among the atomic bomb survivors. For those who have been exposed as adults, the observations are essentially complete, and the risk estimates are, therefore, firmly based on observations. Those who have been exposed as children, have still not reached the age of high cancer incidence. Their observation is, therefore, still incomplete, and the risk estimates are correspondingly uncertain. The modelling of risk has predominantly been based on the postulate, that the relative risk (i.e. the actual cancer rate divided by the age specific normal rate) depend on dose and on age at exposure, and that it does not decline with time since exposure. The high relative risks observed at young ages lead, therefore, with this type of model, to high estimates of life time attributable risk. The ICRP recommendations contain these high risk estimates for young ages at exposure; the high sensitivity of children and juveniles has, indeed, become one of the basic tenets of radiation protection. It is here shown that these conclusions are still hypothetical, because they are merely a matter of the choice of the model. An alternative model assumes a dependence of the excess relative risk on age attained, rather than age at exposure. This model fits the data equally well, and predicts no increased risk for young ages at exposure. A decision between the two models is not possible at present, it will have to await the continued follow- up of those who survived the atomic bombs as children. The ICRP has been criticised for postulating a dose reduction factor (DDREF) in their nominal risk coefficients. If they abandoned this factor, and used the age attained model, rather than their present model, their numerical risk coefficients would remain unchanged.