Universal measuring site for the determination of tissue-impedance variations in relation to blood perfusion]

In view of the importance of impedance plethysmography requirements are formulated for a modern impedance measuring device basing on a long experience with this method of measurement. The principle mode of action of the measuring equipment and the pneumatics with the timing element are described. A number of recordings is shown to illustrate the universality of the measuring equipment.     

Switch region content of hybridomas: the two spleen cell Igh loci tend to rearrange to the same isotype

We have examined the switch region content of 25 hybridomas that secret antibodies of various isotypes with specificity for phosphocholine or glycoproteins of herpes simplex virus. These Southern hybridization experiments included probes for the murine JH region as well as probes for the mu, gamma 3, gamma 1, gamma 2b, gamma 2a, and alpha switch regions. For 22 of the hybridomas, the deletion model of the heavy chain switch fits the data well--all switch regions upstream of the rearranged (and expressed) switch regions are deleted and all switch regions downstream remain in the germline configuration. As exceptions to a simple deletion model of the switch recombination, we have observed two, and perhaps three, examples of switch region rearrangements downstream of an expressed heavy chain gene. The 25 hybridoma DNA samples include 28 rearranged gamma switch regions; the sizes of at least 25 of these rearranged fragments are consistent with recombination in the tandemly repeated sequences associated with gamma genes. For those hybridomas with two spleen cell-derived Igh loci, including three mu-expressers, three gamma 3-expressers, four gamma 1-expressers, and one gamma 2b-expresser, the two loci tend to be rearranged to the same switch region, suggesting that the heavy chain switch rearrangement is an isotype-specific event. The exceptions within this group include three hybridomas in which the switch seems to be incomplete--on one chromosome the JH complex is rearranged to the S gamma 3 region, while on the other it remains associated with the S mu region. A second group of hybridomas, which includes four gamma 3-expressers, have both gamma 3 and gamma 1 switch rearrangements. Each of these four hybridomas includes three rearranged JH segments, suggesting that they may be the result of an unusual differentiative pathway or a technical artifact. These experiments suggest that the heavy chain switch rearrangement in normal spleen cells is a deletion event that occurs within tandemly repeated elements. The rearrangement is mediated by factors with partial, or perhaps complete, isotype specificity.     

Reaction of (bromoacetamido)nucleoside affinity labels with ribonuclease A: evidence for steric control of reaction specificity and alkylation rate

Four new bromoacetamido pyrimidine nucleosides have been synthesized and are affinity labels for the active site of bovine pancreatic ribonuclease A (RNase A). All bind reversibly to the enzyme and react covalently with it, resulting in inactivation. The binding constants Kb and the first-order decomposition rate constants k3 have been determined for each derivative. They are the following: 3'-(bromoacetamido)-3'-deoxyuridine, Kb = 0.062 M, k3 = 3.3 X 10(-4) s-1; 2'-(bromoacetamido)-2'-deoxyxylofuranosyluracil, Kb = 0.18 M, k3 = 1700 X 10(-4) s-1; 3'-(bromoacetamido)-3'-deoxyarabinofuranosyluracil, Kb = 0.038 M, k3 = 6.6 X 10(-4) s-1; and 3'-(bromoacetamido)-3'-deoxythymidine, Kb = 0.094 M, k3 = 2.7 X 10(-4) s-1. 3'-(Bromoacetamido)-3'-deoxyuridine reacts exclusively with the histidine-119 residue, giving 70% of a monoalkylated product substituted at N-1, 14% of a monoalkylated derivative substituted at N-3, and 16% of a dialkylated species substituted at both N-1 and N-3. Both 2'-(bromoacetamido)-2'-deoxyxylofuranosyluracil and 3'-(bromoacetamido)-3'-deoxyarabinofuranosyluracil react with absolute specificity at N-3 of the histidine-12 residue. 3'-(Bromoacetamido)-3'-deoxythymidine alkylates histidines-12 and -119. The major product formed in 57% yield is substituted at N-3 of histidine-12. A monoalkylated derivative, 8% yield, is substituted at N-1 of histidine-119. A disubstituted species is formed in 14% yield and is alkylated at both N-3 of histidine-12 and N-1 of histidine-119. A specific interaction of the "down" 2'-OH group, unique to 3'-(bromoacetamido)-3'-deoxyuridine, serves to orient the 3'-bromoacetamido residue close to the imidazole ring of histidine-119. The 2'-OH group of 3',5'-dinucleoside phosphate substrates may serve a similar role in the catalytic mechanism, allowing histidine-119 to protonate the leaving group in the transphosphorylation step. (Bromoacetamido)nucleosides are bound in the active site of RNase A in a variety of distinct conformations which are responsible for the different specificities and alkylation rates.     

Differences in human chemosensory evoked potentials to olfactory and somatosensory chemical stimuli presented to left and right nostrils

The aim of the present study was to determine whether the recordingof chemosensory evoked potentials (CSEP) in healthy subjects(n = 11) can be helpful in differentiating the olfactory ortrigeminal component possessed by odorants. By recording fromseveral positions on the surface of the skull it was attemptedto ascertain whether different generators are responsible forCSEP associated with the different sensory components of odorants.Birhinal stimulation was used in order to establish an interactionbetween the stimulated side and the stimulated sensory channel.The four substances carbon dioxide, menthol, hydrogen sulphideand vanillin were tested. EEG was recorded from eight positions. The CSEPs' topographical distribution revealed differences inthe location of maximum amplitudes following stimulation withdifferent types of stimulants. Largest amplitudes always appearedat the vertex when trigeminal stimulants (menthol, carbon dioxide)were presented, whereas olfactory substances (vanillin, hydrogensulphide) elicited maximal amplitudes at parietal and centralsites. This suggests that at least two neuronal populationsare involved in the cortical generation of CSEP. Another interestingfinding was that the evoked potentials differed in relationto the stimulated side. Generally, responses to carbon dioxide,menthol and hydrogen sulphide had shorter latencies and smalleramplitudes after stimulation of the left nostril. In contrast,after stimulation with vanillin latencies were shorter and amplitudestended to be smaller after stimulation of the right side. Sincevanillin was the only substance which always evoked pleasantand positive associations, it was assumed that the differencesin CSEP after stimulation of the two nostrils are related tothe different processing of emotional information within thetwo hemispheres.     

Mutations in Methanobacterium formicicum conferring resistance to anti-80S ribosome-targeted antibiotics

Summary Mutants of Methanobacterium formicicum resistant to the anti-80S ribosome-targeted inhibitor anisomycin were isolated and characterized. The resistance phenotype is correlated with a mutationally altered 50S ribosomal subunit. Anisomycin resistance in the mutants is accompanied by cross-resistance to other inhibitors of the 80S peptidyl-transferase centre like narciclasine, bruceantin, trichodermin and verrucarin A and by hypersensitivity to sparsomycin. This phenotype is identical to that reported for anisomycin-resistant mutants of yeast; it appears therefore, that the anisomycin interaction sites on the 70S ribosomes from M. formicicum bear the structural features typical of eukaryotic 80S organelles.     

Studies of the GTPase domain of archaebacterial ribosomes

Ribosomes from the methanogens Methanococcus vannielii and Methanobacterium formicicum catalyse uncoupled hydrolysis of GTP in the presence of factor EF-2 from rat liver (but not factor EF-G from Escherichia coli). In this assay, and in poly(U)-dependent protein synthesis, they were sensitive to thiostrepton. In contrast, ribosomes from Sulfolobus solfataricus did not respond to factor EF-2 (or factor EF-G) but possessed endogenous GTPase activity, which was also sensitive to thiostrepton. Ribosomes from the methanogens did not support (p)ppGpp production, but did appear to possess the equivalent of protein L11, which in E. coli is normally required for guanosine polyphosphate synthesis. Protein L11 from E. coli bound well to 23S rRNA from all three archaebacteria (as did thiostrepton) and oligonucleotides protected by the protein were sequenced and compared with rRNA sequences from other sources.     

d-2-hydroxyisocaproate dehydrogenase from Lactobacillus casei

Summary The new enzyme d-2-hydroxyisocaproate dehydrogenase (NAD⁺-dependent) was detected in strains of the genus Lactobacillus and related genera. Straight and branched chain aliphatic as well as aromatic 2-ketocarboxylic acids are stereospecifically reduced to the corresponding d-2-hydroxycarboxylic acids according to the following equation:R-CO-COOH + NADH + H⁺ R-CHOH-COOH + NAD⁺ The enzyme is called d-hydroxyisocaproate dehydrogenase by us because 2-ketoisocaproate is the substrate with the lowest K_M-value. NAD(H) as a cofactor cannot be replaced by NADP(H). Because of its broad substrate specificity we chose the strain Lactobacillus casei ssp. pseudoplantarum (DSM 20 008) for enzyme production and characterization. d-2-hydroxyisocaproate dehydrogenase could be purified 180-fold starting with 500 g of wet cells.The purification procedure involved liquid-liquid extraction with aqueous two-phase systems and ion-exchange chromatography. At this stage the enzyme has a specific activity of 25 U/mg and can be used for technical applications. Further purification up to a homogeneous protein with a specific activity of 110 U/mg can be achieved by chromatography on Amberlite CG 50 at pH 3.5. Properties important for technical application of the d-HicDH were investigated, especially the substrate specificity and the optimum pH- and temperature ranges for activity and stability of the catalist.     

Häufigkeit der Sichttypen in den Erbsystemen Haptoglobin,Gc, saure Erythrocytenphosphatase,Phosphoglucomutase und Adenylatkinase sowie den Erbeigenschaften Gm(1), Gm(2) und Inv(1) bei Deutschen (aus dem Raum Freiburg i. Br. und Köln) und bei Türken

Zusammenfassung Die an 274 Türken und einer mehrfachen Zahl Deutscher (787–5030) durchgeführten Untersuchungen ergaben eine etwas größere Häufigkeit des Gens Hp¹ im Raum Köln und eine größere des Gens Inv¹ im Raum Freiburg i. Br. Bei Türken sind die Allele Hp², Gm¹, P^b und PGM² häufiger, die Allele Hp¹, Gm^1,2, P_a, P_c und PGM¹ seltener als bei Deutschen. Die Frequenzen im Gc- und AK-System stimmen überein.

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Summary There was found a higher frequency of Hp¹ and a lower of Inv¹ in the population of Cologne than in the population of Freiburg. The frequencies of Hp², Gm¹, P^b and PGM² in the Turkish population were found to be higher than those in the German population; the frequencies of Hp¹, Gm^1,2, P^a, P^c and PGM¹ were found to be lower. In the systems Gc and AK the frequencies in the two populations are not significantly different.

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(Direktor: Prof. Dr. R. Haas)

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(Direktor: Prof. Dr. G. Pulverer)

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(Direktor: Prof. Dr. C. Bennholdt-Thomsen)     

The effects of prolonged emersion and submersion by tidal manipulation on marine macrobenthos

Effects of tidal manipulation, resulting in prolonged periods of emersion and submersion or in protracted tidal cycles, on estuarine benthic animals are reviewed.Prolonged submersion periods did not show effects on mortality of most benthic animals tested, with the exception of the crumb-of-bread sponge Halichondrea panicea, which, at low water-flow rates, was covered with a layer of bacteria and subsequently died.Protracted low-water periods of 18 hours during several weeks hardly caused any mortality. However, protracted low-water periods of 30 hours during some weeks or emersion during several days caused a strong increase in mortality, depending on: the duration of emersion, temperature, condition of the animals, species and age. At temperatures below –1 °C and above 24 °C mortality was generally high. Animals with a low glycogen content were more sensitive to emersion than those with a high content. Species with a shell and those that are relatively big were less sensitive than those without a shell or of small size.The reproductive cycle of benthic animals could be delayed or accelerated by both emersion and submersion.