Showing papers by "Humboldt University of Berlin published in 1987"

The role of dipeptidyl peptidase IV in human T lymphocyte activation. Inhibitors and antibodies against dipeptidyl peptidase IV suppress lymphocyte proliferation and immunoglobulin synthesis in vitro.

Abstract: Dipeptidyl peptidase IV (DP IV), an ectoenzyme in the cell membrane of T lymphocytes, is an important constituent in the process of lymphocyte activation. This conclusion is drawn from the following observations: (a) Proliferation of peripheral blood lymphocytes induced by mitogenic lectins (phytohemagglutinin, concanavalin A, pokeweed mitogen) is suppressed in the presence of DP IV inhibitors. This effect is specific and applies to an irreversible suicide inhibitor as well as to a competitive one in a dose-dependent fashion. (b) Inhibition of DNA synthesis was also induced by a polyclonal anti-DP IV immunoglobulin. (c) As a consequence of impaired T cell function the production of immunoglobulins by pokeweed mitogen-stimulated lymphocytes is also markedly reduced in the presence of DP IV inhibitors.

A kinetic model for lipoxygenases based on experimental data with the lipoxygenase of reticulocytes

Abstract: A comprehensive kinetic model for lipoxygenase catalysis is proposed which includes the simultaneous occurrence of dioxygenase and hydroperoxidase activities and is based on the assumption of a single binding site for substrate fatty acid and product. The aerobic reaction of purified lipoxygenase from rabbit reticulocytes with 9,12(Z,Z)-octadecadienoic acid (linoleic acid) as substrate was studied. The rate constants and the dissociation constants of this enzyme were calculated for the model from progress curves; the model describes correctly the experimental data. The following kinetic features of the reticulocyte enzyme are assumed to apply generally to lipoxygenases. (a) The enzyme shows autoactivation by its product. (b) The rate-limiting step is the hydrogen abstraction. (c) Both substrate fatty acid and its product are competitive inhibitors of the lipoxygenase. (d) Lowering the oxygen concentration enhances the degree of substrate inhibition, whereas product inhibition is not influenced. (e) If substrate is in excess the oxygen concentration determines the share of dioxygenase and hydroperoxidase activities of the enzyme. As predicted from the model it was found that at low concentrations of oxygen the regio- and stereo-specificities of the dioxygenation are diminished. During the autoactivation phase the steady-state approximation does not hold.

Formation of lipoxin B by the pure reticulocyte lipoxygenase via sequential oxygenation of the substrate

Abstract: The pure reticulocyte lipoxygenase converts 15Ls-hydroxy-5,8,11,13(Z,Z,Z,E)-icosatetraenoic acid (15Ls-HETE) methylester to a complex mixture of products containing 5Ds,14LR,15Ls-trihydro(pero)xy-6E,8Z,10E,12E-icosatetraenoate methyl ester (lipoxin B methyl ester), 5Ds,15Ls-DiH(P)ETE methyl ester and four 8,15Ls-DiH(P)ETE methyl ester isomers [DiH(P)ETE = dihydro(pero)xy-icosatetraenoic acid]. After a short incubation period (15 min) 5Ds,15Ls-DiH(P)ETE methyl ester was found to be the main product, whereas after a 3-h incubation lipoxin B methyl ester was the predominant product. The reaction shows a remarkable stereoselectivity since only small amounts of other trihydroxy tetraenes are formed. Anaerobiosis, heat inactivation of the enzyme, or incubation in the presence of lipoxygenase inhibitors (icosatetraynoic acid, nordihydroguaiaretic acid) completely abolished the reaction. The complete steric structure of the major tetraene product (lipoxin B methyl ester) was established by ultraviolet spectroscopy, HPLC on four different types of columns, gas chromatography/mass spectrometry, gas/liquid chromatography of the ozonolysis fragments of the menthoxycarbonyl derivatives, and by 400-MHz 1H-NMR. Atmospheric oxygen was incorporated at carbon-5 and carbon-14 into the major product. 5Ds,15Ls-DiH(P)ETE methyl ester was shown to be an intermediate in the synthesis. Lipoxin B was also formed during the oxygenation of arachidonic acid, 15Ls-HETE and 5Ds,15Ls-DiHETE. The results presented here indicate that lipoxin B can be formed by pure lipoxygenases via a sequential oxygenation of arachidonic acid or its hydro(pero)xy derivatives.

Optical Study of Phase Transition from Tetrahedrally into Octahedrally Coordinated MnS

Abstract: MnS thin films on glass substrates prepared by thermal vacuum evaporation show zincblende/wurtzite and rocksalt structure, respectively in dependence of the substrate temperature. The thermal-treatment induced transition from the tetrahedrally (ZB/W) into the octahedrally (RS) coordinated phase is studied optically by photoluminescence, excitation, and absorption spectroscopy and by X-ray diffraction measurements. Emission bands in the red and infrared spectral region are observed being characteristic for the tetrahedrally and octahedrally coordinated phase, respectively. The excitation due to energy transfer by Frenkel excitons is studied in various stages of the ZB/W RS phase transition. As a result of this transition a shift of the absorption edge by about 300 meV to lower energies is found ascribed to a corresponding energy-gap difference. MnS-Dunnschichten auf Glassubstrat, die durch thermische Vakuumverdampfung hergestellt wurden, zeigen in Abhangigkeit von der Substrattemperatur Zinkblende/Wurtzit- bzw. Steinsalz-Struktur. Der durch Temperung induzierte ubergang aus der tetraedrisch (ZB/W) in die oktaedrisch (RS) koordinierte Phase wird optisch durch Photolumineszenz-, Anregungs- und Absorptionsspektroskopie und durch Rontgenbeugungs-Messungen untersucht. Es wurden Emissionsbanden im roten und infraroten Spektralbereich beobachtet, die charakteristisch fur die tetraedrisch bzw. oktaedrisch koordinierte Phase sind. Die Anregung infolge Energietransfer durch Frenkel-Exzitonen wird in verschiedenen Stadien der ZB/W RS-Phasenumwandlung untersucht. Als Ergebnis dieses Phasenubergangs wird eine Verschiebung der Absorptionskante um etwa 300 meV zu kleineren Energien hin gefunden, die einer entsprechenden Differenz der Energielucken zugeschrieben wird.

Studies in postmortem dopamine uptake. II. Alterations of the synaptosomal catecholamine uptake in postmortem brain regions in schizophrenia.

Abstract: The effect of various post-mortem storage times and temperatures on the kinetic parameters of synaptosomal high-affinity dopamine (DA) uptake was studied in rat nucleus accumbens. After post-mortem storage up to 48 hours of rat headsin situ at 22 ‡C the KM data increase moderately in contrast to the Vmax data decreasing rapidly (t1/2=30 hours); at 2‡C similar changes were observed. The post-mortem changes of the kinetic parameters of noradrenaline (NA) and serotonin (5 HT) uptake were shown in this model to be similar. It is proposed to use this animal model for correcting the kinetic data of DA, NA and 5 HT uptake in human brains regarding the various post-mortem delays. Furthermore, in cryopreservation experiments using a two-step freezing procedure in liquid nitrogen of brain pieces preincubated with dimethylsulfoxide DA uptake of rat and human brain synaptosomes was unchanged after freezing-thawing. The same is true for both NA and 5 HT uptake as demonstrated in human brain tissue. Therefore, post-mortem human brain seems to be suitable for investigating synaptosomal DA, NA, and 5 HT uptake after cryopreservation and correcting for post-mortem delay, when determining kinetic parameters.

Curing BB rats of freshly manifested diabetes by short-term treatment with a combination of a monoclonal anti-interleukin 2 receptor antibody and a subtherapeutic dose of cyclosporin A.

Abstract: The BioBreeding (BB) rat develops spontaneously a syndrome resembling human type I diabetes mellitus. The short-term treatment of newly diagnosed diabetic BB rats with the anti-interleukin 2 receptor (IL2R) monoclonal antibody ART-18 in combination with a subtherapeutic dose of cyclosporin A for 10 days, a treatment shown previously to eliminate specifically antigen-activated IL 2R+ T lymphocytes by sparing suppressor cells, resulted in (a) normoglycemia in 70% of the animals, (b) the maintenance of B cell volume density and (c) an increase in pancreatic insulin content. Moreover, the glucose tolerance of successfully treated animals was not significantly different from that of normoglycemic BB rats during the whole observation period (up to 120 days after the end of the therapy). This is the first report on successful treatment of a spontaneous autoimmune disease by a short-term and specific immunosuppressive regimen with limited side effects.

Diagnostic Value of Low-Molecular Mass Proteins in Serum for the Detection of Reduced Glomerular Filtration Rate

Abstract: Summary: The diagnostic value of the low-molecular mass proteins ribonuclease, s2-microglobulin, and lysozyme in serum for the detection of reduced glomerular filtration rates was evaluated. The values of these proteins and of serum creatinine investigated in 52 patients suffering from chronic renal diseases were plotted against "m-Tc^diethylenetrianiinopentaacetate clearance as an indicator of glomerular filtration rate. Log- transformed data showed a gpod fit pf linearity. Considering the 95% confidence limits of the regression equations, ribonuclease increased above the normal range when the glomerular filtration rate was lower than 1.24 ml/s whereas the other analytes partly remained within their normal limits. Out of those 18 patients with glomerular filtration rates lower than 1.24 ml/s, all patients showed elevated ribonuclease levels. s2- Microglobulin, creatinine, and lysozyme were increased in 17, 14, and 12 cases, respectively. Ribonuclease and s2-microglobulin showed similar results when other diagnostic criteria (specificity, efficiency and predic- tive values) were taken into account. We recommend ribonuclease determination in serum for the detection of reduced glomerular filtration rate in the normal range of creatinine. The test is diagnostically powerful, cheap and easy to perform.

Morphometric and densitometric investigations of protoplasmic astrocytes and neurons in human hepatic encephalopathy

Abstract: Summary Morphometric and densitometric evaluations were made of nuclei of astrocytes and nerve cells of 49 cases with chronic liver diseases and of 9 control cases. The data measured from Nissl-stained specimens of putamen were compared with clinical degrees of encephalopathy and with blood ammonia levels. The parameters measured included nuclear area and optical density of nuclei. The nuclear area of astrocytes (AAREA), on average, was found to grow significantly along with aggravation of encephalopathy, that growth being from 39μm 2 in the control group to about 60μm 2 in cases of severe encephalopathy. Furthermore the proportion of astrocyte nuclei with an area above 70μm 2 (ALRG) and the proportion of the optical light area of the total nuclear area (AHOLE) rises. Mean compactness (ACEXT) and mean extinction of astrocyte nuclei (AMEXT) dropped along with growing severity of encephalopathy. Mean blood ammonia levels rose from 42μmol/l in cases with no microscopically detectable signs of encephalopathy to about six times higher values in cases with severe encephalopathy. Optical density of astrocyte nuclei was negatively correlated and mean nuclear area positively correlated to blood ammonia levels. No characteristic morphometric and densitometric changes of nerve cell nuclei were recordable from the putamen.

Prolongation of rat pancreatic islet allograft survival by treatment of recipient rats with monoclonal anti-interleukin-2 receptor antibody and cyclosporin

Abstract: Since interleukin-2-receptor expressing cells play a role in allograft rejection, we investigated the effect of anti-interleukin-2 receptor monoclonal antibody treatment on graft survival of allografted pancreatic islets. When pancreatic islets obtained from Lewis A-rats (haplotype RT1a) were grafted under the kidney capsules of streptozotocin-diabetic Lewis rats (haplotype RT1u), the recipients relapsed into hyperglycaemia within 11 days (7±1 days). Treatment of the recipient rats with low-dose cyclosporin (1.5 mg/kg body weight) had no effect on allograft survival (9±1 days). The application of anti-interleukin-2 receptor monoclonal antibody (1mg/kg body weight) for 10 days resulted in a prolongation of allograft survival (42.5±15.3,p 120 days) associated with glucose intolerance was observed. When the recipients were treated for 10 days with cyclosporin and anti-interleukin-2 receptor monoclonal antibody, the allograft survival was also prolonged (45.1±14.6,p<0.01); again 3 out of 11 animals remained permanently normoglycaemic while exhibiting a normal glucose tolerance.

Effects of Age and Sex on Auditory Brain Stem Response A New Aspect

Abstract: The age and sex dependence of the latencies and interpeak intervals (IPI) of the auditory brain stem response (ABR) was investigated in 86 males and 69 females. The latencies of the waves I, III and V as well as the IPI I-V and III-V are significantly shorter in females than in males. A correlative linear dependence on age could be shown for the latencies of waves I, III and V in males and for the wave V latency in females. The slopes of the regression lines calculated for the dependence of ABR latencies I, III and V on age tend to be steeper in males than in females. The slope increases from wave I to wave V. The male and female regression lines intersect the latency axis at about the same point (at the same latency value at age A=O). On the basis of these results, the hypothesis is established, that age and sex dependence is not caused by different mechanisms. The ABR latency differences between males and females are in the main the result of the ABR age dependence being less pronounced in females than ...

Pharmacokinetics of adriamycin, adriamycinol, and antipyrine in patients with moderate tumor involvement of the liver

Abstract: The pharmacokinetics of adriamycin, its metabolite adriamycinol, and antipyrine were studied in 17 patients with moderate tumor involvement of the liver and compared to that of 19 tumor patients with normal liver function (Preiss et al. 1985). The individual liver function parameters deviated from normal by a factor ranging from 2.5 to 12.2 the t 1/2α and t 1/2β, the AUC (corrected for body weight and dose) and the total body clearance (CL, corrected for body weight) of adriamycin did not differ significantly between the two groups of patients. Likewise, there was no difference in the kinetic parameters of antipyrine between the two groups. Unlike adriamycin and antipyrine, adriamycinol was found to have a significantly longer t 1/2term (60.5 vs 28.3 h, P<0.001), an increased AUC (3.00 vs 1.43 h/ug per ml, P<0.02), and a higher AUCadriamycinol/AUCadriamycin ratio (0.94 vs 0.52, P<0.02) in patients with moderate tumor involvement of the liver. The CL, the AUC, and t1/2β of adriamycin correlated significantly (P<0.001 and P<0.01) with the corresponding kinetic parameters of antipyrine, but not with the usual liver function parameters. No correlation could be found between the kinetic parameters of adriamycinol and those of antipyrine.

Photochemiluminescent detection of antiradical activity. I. Assay of superoxide dismutase.

Abstract: The luminol sensitized photogeneration of superoxide radicals was combined with their luminol-dependent chemiluminescent detection. The inhibition of chemiluminescence by superoxide dismutase (SOD) versus enzyme concentration in reciprocals was strongly linear. The amount of SOD notable for 50% inhibition was between 115 and 500 ng for different enzyme preparations.

The rat C-reactive protein - isolation and response to experimental inflammation and tissue damage

Abstract: A new isolation procedure of rat C-reactive protein (CRP) by affinity chromatography on aminocoupled phosphorylcolamine-Sepharose is described. CRP serum level of rats injured by turpentine injection or two different arthritis models was determined to test the potency of this protein as an marker of inflammation. The influence of repeated adminstration of carbon tetrachloride as a hepatotoxic agent was investigated in the same way.

Donor‐Type Tm Centres in ZnS Crystals

Abstract: 4f—4f excitation and emission spectra involving various intermanifold transitions are determined for two Tm3+ centres in ZnS crystals by dye-laser site-selective measurements at helium temperatures. A crystal-field analysis together with polarization data indicates that in both cases Tm is located on lattice sites, probably Zn sites. One of the sites (D3) is thought to be in „unperturbed” environment, whereas in the second case (D2) the four nearest-neighbour atoms are probably replaced by impurity atoms. The excitation and deexcitation mechanisms of the blue 1G4 3H6 emission of these centres are studied by site-selective broad-band excitation spectra and kinetical measurements. These studies demonstrate that donor-acceptor pairs involving the two Tm centres as the donors play an important role in the excitation process. Estimates are given of the relevant pair to 4f state transfer rates. 4f—4f-Anregungsspektren und -Emissionsspektren von zwei Tm3+-Zentren in ZnS-Kristallen werden fur verschiedene ionare Ubergange durch zentrenselektive Messungen mit Hilfe von Farbstoff-lasern bei Heliumtemperaturen bestimmt. Eine Kristallfeldanalyse last zusammen mit Polarisationsdaten darauf schliesen, das in beiden Fallen Tm auf Gitterplatzen, wahrscheinlich Zn-Platzen eingebaut ist. Es ist anzunehmen, das einer dieser Platze (D3) eine „ungestorte„ Umgebung besitzt, wahrend im zweiten Fall (D2) die vier nachsten Nachbaratome wahrscheinlich durch Fremd-atome ersetzt sind. Die Anregungs- und Deexzitationsmechanismen der blauen 1G4 3H6-Emission dieser Zentren werden mit Hilfe zentrenselektiver breitbandiger Anregungsspektren und entsprechender kinetischer Messungen untersucht. Diese Untersuchungen zeigen, das Donator—Akzeptor-Paare, in denen die Tm-Zentren als Donatoren wirken, eine wichtige Rolle im Anregungs-prozes spielen. Fur die Ubergangsraten Paarzustande 4f-Zustande werden Abschatzungen gegeben.

Cell biology of human IgM-producing hybridomas derived from a fusion of human spleen lymphocytes with mouse myeloma cells.

Abstract: Hybrids were derived from the fusion of mouse myeloma cells with human spleen cells from a patient with active idiopathic thrombocytopenia Of 288 initally seeded cultures, 186 were found to produce human Ig The growth and Ig production rates, cloning efficiencies using different feeder layers and the karyotype were determined for 9 clones that stably produced human monoclonal IgM (2-100 ug/ml) for at least 9 months All cells of the Ig-producing hybridoma clones were positive for cytoplasmic-Ig, whereas only 20-65% of cells expressed surface Ig ( u and chains) Human monoclonal antibodies in mass cultures were derived in serum-free PRMI 1640 medium Two clones produced human IgM (nearly 2 mg/ml) in the ascitic fluid of nude mice Feeder cells of peritoneal macrophages from Balb/c mice enabled more efficient recloning of human x mouse hybrids than did thymocytes Nearly all subclones derived from 2 clones were found to produce the same monoclonal antibodies as the parental lines Information on the indiv

Estimation of the endogenous N proportions in ileal digesta and faeces in 15N-labelled pigs.

Abstract: Four 40 kg castrated male pigs fitted with simple 'T' cannulas in the terminal ileum were given 15N-labelled ammonium salts, added to a low protein diet, for 6 days. Excretion of 15N in urine and faeces was monitored daily throughout the labelling and subsequent experimental periods. During the experimental period the pigs were given a diet based on wheat and fish meal, supplemented with varying levels of partially hydrolysed straw meal to give crude fibre contents ranging from 40 to 132 g/kg. After adaptation to the particular levels of straw meal, faeces and ileal digesta were collected during successive 24 h periods. N digestibility values were determined by the chromic oxide ratio method. The retention of 15N labelled non-specific N was 0.46 of the dose given. The validity of using urine values as a measure of 15N abundance in endogenous N was demonstrated by the similarity of 15N abundance in urine immediately before slaughter at the end of the experiment and in the digestive secretory organs thereafter. The average amount of endogenous N passing the terminal ileum was 3.4 g/day or 0.30-0.50 of total ileal N flow. This was not affected by dietary fibre level. The proportion of faecal N which was of endogenous origin was similar to that in ileal digesta, suggesting similar utilization of endogenous and residual dietary N by hindgut bacteria. Half the endogenous N entering the large intestine was reabsorbed there. Increasing dietary crude fibre from 40 to 132 g/kg increased faecal endogenous N excretion from 1.3 to 2.0 g/animal and day.