Showing papers by "University of Cologne published in 1988"
TL;DR: The degree of cortical folding found in adult human brains has been analyzed using a gyrification index (GI), which permits the description of a mean value for the whole brain, but also a local specific analysis of different brain regions.
Abstract: The degree of cortical folding found in adult human brains has been analyzed using a gyrification index (GI). This parameter permits the description of a mean value for the whole brain, but also a local specific analysis of different brain regions. Correlation analyses of the GI with age, body weight, body length, brain weight and volume of the prosencephalon and the cortex show no significant results. GI values do not differ significantly between male and female brains, right and left hemispheres or right and left sides of the superior temporal plane. The GI shows maximal values over the prefrontal and the parieto-temporo-occipital association cortex. A comparison between the rostro-caudal GI patterns of human brains and those of prosimians and Old World monkeys shows the largest difference over the prefrontal cortex. The mean GI increases from prosimians to human brains with the highest values for non-human primates being in the pongid group.
649 citations
TL;DR: The structure of a series of four-way junctions, constructed by hybridization of four 80 nucleotide synthetic oligonucleotides, is studied, showing the pattern of fragments observed argues strongly for a structure with two-fold symmetry, based on an X shape.
450 citations
TL;DR: The differences in half‐life observed between the different isotypes are independent of the V region carried by the monoclonal antibodies and therefore must relate to each other in the same way as the half‐lives of each class of serum immunoglobulins.
Abstract: We determined the half-lives of several sets of murine monoclonal antibodies spanning all immunoglobulin isotypes in the serum. The antibodies in each set possess the same V region. With this approach, the differences in half-life observed between the different isotypes are independent of the V region carried by the monoclonal antibodies and therefore must relate to each other in the same way as the half-lives of each class of serum immunoglobulins. The half-life of a monoclonal antibody of the gamma 2a isotype is identical to the average half-life of serum IgG2a as previously determined (6-8 days; P. Vieira and K. Rajewsky, Eur. J. Immunol. 1986. 16:871). Therefore, the half-lives determined with monoclonal antibodies possessing the same V region represent the half-life of the serum immunoglobulins. In this way we calculated the half-life of IgM as 2 days, IgG3 and IgG1 as 6-8 days, IgG2b has a half-life of 4-6 days. IgE has a half-life of 12 h. A polymeric form of IgA was found to be eliminated from the serum with a half-life of 17-22 h.
444 citations
TL;DR: The region containing da is cloned and it is found that five recessive lethal da mutations map to a single transcription unit that has sequence similarities with the oncogene myc, with the gene MyoD1, which is involved in myoblast determination, and with the Drosophila achaete-scute complex, which was involved in neuronal precursor determination.
394 citations
TL;DR: The data indicate that the pattern of somatic diversification through hypermutation is shaped by affinity selection, but that only a single point mutation is available in the VH and the VL gene of lambda 1 chain‐bearing anti‐NP antibodies which by itself leads to an increase of hapten‐binding affinity.
Abstract: The influence of structural variation, previously observed in a panel of V186.2 VH/V lambda 1-expressing anti-NP antibodies from the secondary response, on the affinity of these antibodies was examined by site-specific mutagenesis and recombinant antibody construction. A tryptophan----leucine exchange at position 33 in the VH segment of all but one of the high-affinity antibodies is the most frequently observed somatic mutation and by itself leads to a 10-fold higher affinity; all other somatic exchanges are irrelevant for affinity selection. In the single case of a high-affinity antibody without this common exchange, high affinity is mediated by a combination of mutations (including a one-codon deletion) in VH and the particular D-JH rearrangement carried by this antibody. The data indicate that the pattern of somatic diversification through hypermutation is shaped by affinity selection, but that only a single point mutation is available in the VH and the VL gene of lambda 1 chain-bearing anti-NP antibodies which by itself leads to an increase of hapten-binding affinity. Based on the analysis of two secondary response antibodies from which somatic mutations in VH and VL have been eliminated, it is also concluded that the recruitment of B cell clones into the pathway of hypermutation involves a mechanism which is not based upon affinity differences towards the antigen.
258 citations
TL;DR: The ingestion capacity of the freshwater mussel Dreissena polymorpha was attained without forming pseudofaeces with Chlamydomonas reinhardii as food, and the incipient limiting level could be calculated as the quotient of these two values.
Abstract: In common with many other suspension feeders, the freshwater mussel Dreissena polymorpha has a maximum filtration rate at low food concentrations and a maximum ingestion rate at high food concentrations. These high rates, which reflect the potential maximum food uptake of the animal, are called the filtration capacity and the ingestion capacity respectively. The ingestion capacity was attained without forming pseudofaeces with Chlamydomonas reinhardii as food. The incipient limiting level could be calculated as the quotient of these two values. A decrease of the filtration rate at high food concentrations was correlated with changes in pumping activity, which showed more frequent interruptions, or a lower level of water transport. Dreissena can filter out particles of diameter greater than 0.7 μm from the water. Retention reaches a plateau at about 5 μm particle diameter. Scanning electron micrographs of the arrangement of the cilia on the gill filaments are given.
245 citations
TL;DR: In this article, the authors derived analytical formulae for the energy gradient within the quadratic configuration interaction singles and doubles (QCISD) method and their implementation is discussed.
216 citations
TL;DR: In this paper, the wave telescope and discontinuity analysis of magnetometer data from four spacecraft are used to estimate the local electrrical current density, which is the most commonly used method for determining the current density.
197 citations
TL;DR: Plasmacytoma cells, transfected with a vector encoding a membrane‐bound IgM molecule, do not show cell surface IgM expression, although complete IgM molecules are assembled intracellularly, and a 34‐kd protein was found to be associated with IgM only insurface IgM‐positive cells.
Abstract: Plasmacytoma cells, transfected with a vector encoding a membrane-bound IgM molecule, do not show cell surface IgM expression, although complete IgM molecules are assembled intracellularly. The isolation of a surface IgM-positive variant allowed us to analyse molecular requirements of surface IgM expression. Only in surface IgM-positive cells, a 34-kd protein (B34) was found to be associated with IgM. B34 is a glycoprotein which forms a disulphide-linked homodimer. The surface IgM-positive variant cell line expressing B34 also contains transcripts of the pre-B and B cell specific mb-1 gene. The data are discussed in the context of a possible IgM-antigen receptor complex.
187 citations
TL;DR: The Nomogram Method is compared with other temperature methods of estimating the time since death and support in the practical application of the method and data for the accuracy of estimated death time are given.
182 citations
TL;DR: The cDNA clone for strictosidine synthase, the enzyme which catalyzes the stereospecific condensation of tryptamine with secologanin to form the key intermediate in indole alkaloid biosynthesis, strictosalid, has been identified with a synthetic oligodeoxynucleotide hybridization probe in a λgt11 cDNA library of cultured cells of Rauvolfia serpentina.
TL;DR: Because in vitro co-infection of CD4 cells by HBLV and HIV leads to enhanced degeneration, this raises the possibility that infection in AIDS patients by both viruses can aggravate the HIV-induced immunodeficiency.
TL;DR: Using recombinant DNA techniques, a genealogical tree is reconstructed that connects three clonally related B cells producing somatically mutated antibodies to a progenitor cell expressing a germ line-encoded antibody.
Abstract: Using recombinant DNA techniques, we reconstructed a genealogical tree (Sablitzky, F., Wildner, G. & Rajewsky, K. (1985) EMBO J. 4, 345-350) that connects three clonally related B cells producing somatically mutated antibodies to a progenitor cell expressing a germ line-encoded antibody. The somatic mutants had been isolated from an in vivo immune response. The germ line-encoded progenitor antibody bound the antigen with high affinity. Intraclonal affinity maturation occurred stepwise over a 15-fold range.
TL;DR: This work has shown that during neurogenesis in Drosophila, the progenitor cells of the neurogenic ectoderm give rise to two cell types: neural and epidermal, and this developmental switch is not genetically hard-wired, but depends instead on cell-cell communication.
TL;DR: In this paper, numerical simulations of thermal-chemical instabilities in the D-double-prime layer at the core-mantle boundary are presented which show that strong lateral heterogeneities in the composition and density fields can be initiated and maintained dynamically if there is continuous replenishment of material from subduced slabs coming from the upper mantle.
Abstract: Numerical simulations of thermal-chemical instabilities in the D-double-prime layer at the core-mantle boundary are presented which show that strong lateral heterogeneities in the composition and density fields can be initiated and maintained dynamically if there is continuous replenishment of material from subduced slabs coming from the upper mantle. These chemical instabilities have a tendency to migrate laterally and may help to support core-mantle boundary topography with short and long wavelengths. The thermal-chemical flows produce a relatively stagnant D-double-prime layer with strong lateral and temporal variations in basal heat flux, which gives rise to thermal core-mantle interactions influencing the geodynamo.
TL;DR: A novel pathway of B cell development in which cells expressing a selected set of germline antibodies are continuously propagated in the organism is defined.
Abstract: Antibody V gene expression was studied in a subpopulation of murine B cells (Ly1 B) which was enriched by cell transfer and had earlier been shown to persist in the immune system over long periods of time. Among 17 hybridomas derived from Ly1 B cells of two different mice, eight were progeny of only three different B cell precursors which apparently had expanded to clones of large size, in the absence of detectable somatic mutation of their antibody V regions. Furthermore, several clonally independent cells expressed identical, unmutated V genes. These data define a novel pathway of B cell development in which cells expressing a selected set of germline antibodies are continuously propagated in the organism. A Ly1 B cell leukemia derived from a similar transfer experiment expressed a VH gene that had been isolated in three independent Ly1 B cell hybridomas, suggesting that the leukemic cells had been equally selected in this pathway.
TL;DR: The characterisation of the multiple forms of PrP found in SAF fractions purified from mouse brain affected by the ME7 strain of scrapie and a novel, as yet unidentified, amino-acid derivative of the arginine residue at position 3 in mouse PrP is found, which may predispose PrP to form SAF.
Abstract: Scrapie-associated fibrils (SAF) are disease-specific structures found in extracts of the brains of animals affected with scrapie. These structures are pathological aggregates of a normal host protein (PrP). Abnormal post-translational modification of PrP has been suggested to explain its aberrant properties in scrapie-affected brains and although there is a form of PrP in SAF indistinguishable in size from the protein in uninfected brain, lower-molecular-mass variants of PrP are also found in SAF fractions. We report the characterisation of the multiple forms of PrP found in SAF fractions purified from mouse brain affected by the ME7 strain of scrapie. The quantitively major forms of PrP in SAF prepared without the use of proteinase K have the amino-terminal sequence Lys-Lys-Arg-Pro-Lys-Pro-Gly-Gly-, identical to that predicted for the amino-terminus of normal mouse brain PrP. However N-terminal cleavage of some PrP does occur in vivo within a domain of repetitive sequences at sites similar to but distinct from those cut by proteinase K in vitro. This suggests the conformation of the protein in aggregates in vivo does not differ extensively from that in detergent-treated SAF in vitro. We conclude that the size diversity of PrP in SAF is only partly due to N-terminal proteolysis and is independent of the proteolysis that occurs if proteinase K is used in the purification of SAF. Apart from proteolytic changes in the structure of PrP, we found a novel, as yet unidentified, amino-acid derivative of the arginine residue at position 3 in mouse PrP, which may predispose PrP to form SAF.
TL;DR: The presence of altered double helical repeats in supercoiled DNA minicircles indicates that DNA loop formation can define local DNA domains with altered topological properties of the DNA helix.
Abstract: We have used a gel retardation assay to investigate the influence of DNA supercoiling on loop formation between lac repressor and two lac operators. A series of 15 DNA minicircles of identical size (452 bp) was constructed carrying two lac operators at distances ranging from 153 to 168 bp. Low positive or negative supercoiling (sigma = +/- 0.023) changed the spacing between the two lac operators required for the formation of the most stable loops. This reveals the presence of altered double helical repeats (ranging from 10.3 to 10.7 bp) in supercoiled DNA minicircles. At elevated negative supercoiling (sigma = -0.046) extremely stable loops were formed at all operator distances tested, with a slight spacing periodicity remaining. After relaxation of minicircle-repressor complexes with topoisomerase I one superhelical turn was found to be constrained in those minicircles which carry operators at distances corresponding to a non-integral number of helical turns. This indicates that DNA loop formation can define local DNA domains with altered topological properties of the DNA helix.
TL;DR: Southern analysis revealed that all kanamycin resistant plants contained the DNA restriction fragments expected when Ac excises from the NPT-II gene, and the presence of Ac at new locations within the genomic DNA of several transformants was also detected.
Abstract: The maize transposable element Ac has been introduced into potato via the T-DNA (transferred DNA) of Agrobacterium tumefaciens. Ac was inserted within the untranslated leader region of a neomycin phosphotransferase II (NPT-II) gene such that excision restored NPT-II activity. Two approaches to monitor Ac excision were used. (i) Using an Agrobacterium strain harbouring plasmid pGV3850::pKU3, leaf discs were selected on kanamycin (Km) after exposure to Agrobacterium. (ii) Using a strain containing plasmid pGV3850HPT::pKU3, the leaf discs were selected on hygromycin (Hm) and the resulting shoots were checked for NPT-II expression. Thirteen kanamycin resistant shoots transformed with pGV3850::pKU3 were isolated, suggesting that Ac had excised from the NPT-II gene. Out of 43 hygromycin resistant shoots transformed with pGV3850HPT::pKU3, 22 expressed the NPT-II gene, indicating that Ac had undergone excision in approximately 50% of the hygromycin resistant shoots. Southern analysis revealed that all kanamycin resistant plants contained the DNA restriction fragments expected when Ac excises from the NPT-II gene. The presence of Ac at new locations within the genomic DNA of several transformants was also detected.
TL;DR: A prospective study comparing the findings at computed tomography (CT) and magnetic resonance (MR) imaging was conducted on 35 patients who satisfied the following criteria: prior surgery for rectal cancer, perineal pain and/or elevated carcinoembryonic antigen (CEA) level, and a soft-tissue mass in the presacral fossa demonstrated at CT.
Abstract: During an 18-month period, a prospective study comparing the findings at computed tomography (CT) and magnetic resonance (MR) imaging was conducted on 35 patients who satisfied the following criteria: prior surgery for rectal cancer (11 curative resections, 24 rectal amputations), perineal pain and/or elevated carcinoembryonic antigen (CEA) level, and a soft-tissue mass in the presacral fossa demonstrated at CT. Twenty-two patients had tumor recurrence; 13 patients had only inflammatory changes or radiation fibrosis. At a single examination of each patient (with no reference to prior baseline studies), MR imaging was more accurate than CT, largely because MR imaging was more successful in the distinction of recurrence from fibrosis based on the differences in signal intensity on T2-weighted images.
TL;DR: The hepatic synthesis of the plasma proteins might be influenced by asparagine and glutamine depletion as a consequence of the therapy with E. coli asparaginase, in patients with acute lymphatic leukaemia.
Abstract: Several side-effects of asparaginase therapy have been said to be a consequence of the glutaminase activity of Escherichia coli asparaginase, especially the deleterious influence on the liver function. We report here the drug-induced impairments of asparagine and glutamine metabolism in correlation to concentrations changes of plasma proteins, synthesized in the liver, in patients with acute lymphatic leukaemia. One hour after asparaginase application, plasma glutamine decreased to 5% (0-39%: median, range) of the initial values, with a subsequent rise to concentrations slightly lower than those prior to therapy. During the 14 days of drug application the fasting plasma concentrations of glutamine fell to a median of 63% of the pre-therapeutic levels, indicating a depletion of the glutamine pools. Two days after the end of asparaginase application, in one patient the glutamine concentrations increased to the pre-therapeutic range. Plasma concentrations of fibrinogen and antithrombin III decreased to 46% and 56%, respectively, of the initial values, with a slight increase 2 days after the end of therapy. The changes of plasma protein concentrations followed the course of plasma glutamine and asparagine. From that we deduce that the hepatic synthesis of the plasma proteins might be influenced by asparagine and glutamine depletion as a consequence of the therapy with E. coli asparaginase.
Book•
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TL;DR: In the first part of the book, Professor Kolb provides a clear historical narrative of the political, social, economic and cultural developments of the Weimar Republic, setting it within the international context of the inter-war period as mentioned in this paper.
Abstract: In the first part of the book, Professor Kolb provides a clear historical narrative of the political, social, economic and cultural developments of the Weimar Republic, setting it within the international context of the inter-war period. In the second part he surveys and analyses scholarly research in the field which sheds light on the problems and controversies of the period in home and foreign affairs. This text, therefore, provides an excellent introduction to the history of the Weimar Republic and a guide to the state of research for more advanced students. The book contains a detailed chronology and an extensive and up-to-date bibilography, divided by subject, which includes recent English-language studies of the period and translation of German works.
TL;DR: Investigating the occurrence of insoluble conjugated (ester-bound) hydroxycinnamic acids and flavonol glycosides in cell wall preparations from leaves of 54 species from various Conifer taxa finds the bound β-coumaric and ferulic acids seem to be widespread among members of the Coniferae.
TL;DR: Deletion of the Ac sequences between bp 44 and bp 92 or from bp 75 to bp 181 abolishes, or strongly reduces, transposition in cells which are already transgenic for an active Ac element, suggesting that the 3.5‐kb transcript of Ac encodes the only Ac product required for transposition, i.e. the transposase function.
Abstract: We have used the ability of Ac to transpose in tobacco to determine which Ac sequences are required for transposition, using a phenotypic assay for Ac excision from an NPTII gene in which excisions of Ac result in calli resistant to the antibiotic kanamycin (Baker et al., 1987). Here we show that deletion of the Ac DNA which encodes the untranslated leader of the Ac transcript does not prevent Ac excision. A deletion which removes 110 bp including the first 75 bp of long open reading frame prevents Ac excision in tobacco cells. However, it will excise in tobacco cells previously transformed with Ac indicating that deletion of the region prevents the synthesis of a product required for Ac excision. Deletion of the Ac sequences between bp 44 and bp 92 or from bp 75 to bp 181 abolishes, or strongly reduces, transposition in cells which are already transgenic for an active Ac element. This indicates that these deleted elements have lost sequences which are required for the transposon to respond to the transposase, when the enzyme is produced in trans. We also describe a tobacco strain transformed with a Ds element stably inserted wtihin an NPTII gene. This strain is Kms and was retransformed with a construct containing the open reading frame (ORF) of the 3.5-kb Ac transcript expressed from a plant promoter. Expression of the cDNA construct promotes excision of the Ds element. These data suggest that the 3.5-kb transcript of Ac encodes the only Ac product required for transposition, i.e. the transposase function.
TL;DR: In this article, the structural content of spectral mean characteristic was investigated and the connected graphs of connected graphs with spectral mean characteristics were characterized, in particular, for graphs of spectral radius.
Abstract: For a nonregular graph there is exactly one value of p such that the p-mean of its degree sequence is equal to the spectral radius. We try to investigate the structural content of this so-called spectral mean characteristic; in particular, we characterize the connected graphs of spectral mean characteristic 2.
Journal Article•
TL;DR: For the first time a protocol for correlation of the results of an in situ hybridization with the cytological appraisal in the very same smear preparation has been developed for routine diagnostics.
Abstract: To establish a nonradioactive method for demonstrating HPV DNA in routinely treated smears of the uterine cervix (alcohol fixation, staining according to Papanicolaou, preservation), in situ hybridizations were carried out in HeLa and SiHa cells grown on slides. After detailed investigations, the sensitivity and specificity of the biotin-avidin method (10) initially used proved to be inadequate for this purpose. Demonstration of HPV 16 DNA in SiHa cells (SiHa cells only contain 1-2 HPV genome copies) was possible only by use of digoxigenin-labeled HPV 16 gene probes, as well as an improved purification of the sample DNA from vector contaminations. Thus, for the first time a protocol for correlation of the results of an in situ hybridization with the cytological appraisal in the very same smear preparation has been developed for routine diagnostics.
TL;DR: It appears that c-fos specifically stimulates the proliferation of thymic epithelial cells, and may thus indirectly affect T cell development.
TL;DR: In this paper, the Bilzingsleben archaeological site was used for electron spin resonance (ESR) analysis of travertine and tooth enamel of rhinoceros.
Abstract: New absolute dates have been obtained for the Bilzingsleben (D.D.R.) archaeological site, using uranium-series analyses of travertine, and electron spin resonance (ESR) analyses of travertine and tooth enamel of rhinoceros. The results indicate that the site was apparently occupied during interglacial isotope stages 9 or 11. The surrounding terrain has been subsequently dissected by at least three discrete stages of fluvial erosion during succeeding glacial stages. Bilzingsleben is thus shown to be significantly older than the Lower Travertine at the nearby site of Ehringsdorf, assigned to isotope stage 7 by uranium-series dating. The latter assignment is confirmed by new ESR data presented here.
TL;DR: The results of the study show that additional perfusion in the treatment of extremity melanomas is superior to conventional methods.
Abstract: To evaluate the effectiveness of regional hyperthermic cytostatic perfusion in patients with malignant melanomas of the extremities, 107 patients were included in a prospective randomized study. In a control group (A, n = 54) the tumors were widely excised, and the regional lymph nodes were dissected. The patients in the perfusion group (B, n = 53) received additional hyperthermic (42 degrees C) perfusion with melphalan. The disease-free survival time was chosen as the criterion for success. An intermediate evaluation (average follow-up observation period of 550 days) revealed a highly significant difference between the groups (P = 0.0001): 21 recurrences in the control group versus four recurrences in the perfusion group. In a second analysis 3 1/2 years after premature discontinuation, 26 recurrences were diagnosed in Group A, whereas only six recurrences were noted in Group B (P = 0.0001). A retrospective analysis of the entire test group revealed the following figures. In Group A seven recurrences in Stage I were diagnosed, seven in Stage II, and 12 in Stage III. In Group B one was observed in Stage I, one in Stage II, and four in Stage III. The level of significance was calculated to be P = 0.05 in Stage I, P = 0.05 in Stage II, and P = 0.01 in Stage III. The results of the study show that additional perfusion in the treatment of extremity melanomas is superior to conventional methods.