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Ficus obscura var. borneensis is a true myrmecophyte. It spontaneously forms cavities (domatia) in parts of its twigs which open by slits, These occur in the internodes and are usually not swollen. The domatia are inhabited by a variety of non-specific tree-living ants including Crematogaster spp., Cataulacus sp., Tetramorium sp., Cardio condyla sp. and Camponotus sp.. Additionally the plant providL a su~ar-containing secretion from extrafloral nectaries on the lower surfaces of the leaves. Examination of herbarium specimens of 37 other South-east Asian Ficus species did not reveal a single specimen with domatia.
The melanoma·inducing gene of Xiphophorus fish encodes the Xmrk receptor tyrosine kinase. U sing a highly specific antiserum p~oduced against the recombinant receptor expressed with a baculovirus, it is shown that Xmrk is the most abundant phosphotyrosine protein in fish melanoma and thus highly activated in the tumors. Studies on a melanoma cellline revealed that these cells produce an activity that considerably stimulates receptor autophosphorylation. The stimulating activity induces receptor down-regulation and can be depleted from the melanoma cellsupernatant by the immobilized recombinant receptor protein. The fish melanoma cells can thus be considered autocrine tumor cells providing a source for future purification and characterization of the Xmrk ligand.
Two cellular proteins, membrane cofactor protein (MCP) and moesin, were reported recently to be functionally associated with the initiation of a measles virus infection. We bave analyzed the interaction of measles virus with cell surface proteins, using an overlay binding assay with cellular proteins immobilized on nitrocellulose. Among surface-biotinylated proteins from a human rectal tumor cellline (HRT), measles virus, was able to bind only to a 67-kDa proteinthat was identified as MCP. The virus recognized dift'erent isoforms of MCP expressed from human (HRT and HeLa) and simian (Vero) celllines. The binding of measles virus to MCP was abolished after cleavage of the disulfide bonds by reducing agents as weil as after enzymatic release of N-linked oligosaccharides. By contrast, removal of sialic acid or 0-linked oligosaccharides did not aft'ect the recognition of MCP by measles virus. These data indicate that the receptor determinant of MCP is dependent on a conformation of the protein that is maintained by disulfide bonds and N-glycans present in tbe complement binding domains. Our results are consistent with a roJe of MCP as primary attacbment site for measles virus in the initial stage of an infection. The functional relationship between MCP and moesin in a measles virus infection is discussed.
Clinical evidence for a dominant mode of inheritance and anticipation in periodic catatonia, a distinct subtype of schizophrenia, indicates that genes with triplet repeat expansions or other unstable repetitive elements affecting gene expression may be involved in the etiology of this disorder. Because patients affected with dentatorubral-pallidoluysian atrophy (DRPLA) may present with "schizophrenic" symptoms, we have investigated the DRPLA (B 37 CAG repeat) locus on chromosome 12 in 41 patients with periodic catatonia. The B 37 CAG repeat locus was highly polymorphic but all alleles in both the patient and control group had repeat sizes within the normal range. We conclude that variation at the DRPLA locus is unlikely to be associated with periodic catatonia. The evidence for dominant inheritance and anticipation as well as the high prevalence of human brain genes containing trinucleotide repeats justifies further screening for triplet repeat expansions in periodic catatonia.
The effects of the interlenkins IL-7 and IL-9 on cell cycle progression were investigated by conventional [3H]thymidine incorporation and by the bivariate BrdU/Hoechst technique. 8oth IL· 7 and IL-9 drive phytohemagglutinin-activated T cells through more than one cell cycle, but IL-7 wasmorepotent on cell cycle progression than IL-9. Neither synergistic nor inhibitory effects were seen between various combinations of the lymphokines IL-7, IL-9 and IL-4 compared to each lymphokine alone. When T cells are activated with phytohemagglutinin for 3 days, all or most IL-4 responsive cells respond to IL-7 as weil, whereas only a part of IL-7 responders are IL-4 responders. In contrast, when T cells are activated with phytohemagglutinin for 7 days, the quantitative data of the cell cycle distribution soggest that the population of IL-7 responders is at least an overlapping, if not a real subset of the population of the IL-4 responders.
Monoclonal hBMP/NCP (human bone morphogenetic protein anrl associaterl noncollagenous proteins) antiborlies of the lgG class were prorlucerl. In vitro, 12 of 19 hBMP/NCP antiborlies showerl functional inhibition of hBMP/ NCP-induced chondroneogenesis in a neonatal muscle tissue assay. Inducing factors were characterized by their inhibiting antibodies with immunoblotting. Several peptide factors seem to be involved in the cascade of inducerl chondro- and osteogenesis.
The cytoskeleton and/or membrane skeleton has been implicated in the regulation of N-formyl peptide receptors. The coupling of these chemotactic receptors to the membrane skeleton was investigated in plasma membranes from unstimulated and desensitized human neutrophils using the photoreactive agonist N-formyl-met-leu-phelys-N\(^6\)-[\(^{125}\)I]2(p-azidosalicylamido)ethyl-1,3'-dithiopropionate (fMLFK-[\(^{125}\)I]ASD). When membranes of unstimulated cells were solubilized in Triton-X 100, a detergent that does not disrupt actin filaments, only 50% of the photoaffinity-labeled receptors were solubilized sedimenting in sucrose density gradients at a rate consistent with previous reports. The remainder were found in the pellet fraction along with the membrane skeletal actin. Solubilization of the membranes in the presence of p-chloromercuriphenylsulfonic acid, elevated concentrations of KCI, or deoxyribonuclease I released receptors in parallel with actin. When membranes from neutrophils, desensitized by incubation with fMLFK-e 251]ASD at 15°C, were solubilized, nearly all receptors were recovered in the pellet fraction. lncubation of cells with the Iigand at 4°C inhibited desensitization partially and prevented the conversion of a significant fraction of receptors to the form associated with the membrane skeletal pellet. ln these separations the photoaffinity-labeled receptors not sedimenting to the pellet cosedimented with actin. Approximately 25% of these receptors could be immunosedimented with antiactin antibodies suggesting that N-formyl peptide receptors may interact directly with actin. These results are consistent with a regulatory role for the interaction of chemotactic N-formyl peptide receptors with actin of the membrane skeleton.
Signal transduction via receptors for N-formylmethionyl peptide chemoattractants (FPR) on human neutrophils is a highly regulated process which involves participation of cytoskeletal elements. Evidence exists suggesting that the cytoskeleton and/or the membrane skeleton controls the distributJon of FPR in the plane of the plasma membrane, thus controlling the accessibility of FPR to different proteins in functionally distinct domains. In desensitized cells, FPR are restricted todomains which are depleted of G proteins but enriched in cytoskeletal proteins such as actin and fodrin. Thus, the G protein signal transduction partners of FPR become inaccessible to the agonist-occupied receptor, preventing cell activation. The mechanism of interaction of FPR with the membrane skeleton is poorly understood but evidence is accumulating that suggests a direct binding of FPR (and other receptors) to cytoskeletal proteins such as actin.
Desensitization of N-formyl peptide chemoattractant receptors (FPR) in human neutrophils results in association of these receptors to the membrane skeleton. This is thought to be the critical event in the lateral segregation of receptors and guanyl nucleotide-binding proteins (G proteins) within the plane of the plasma membrane resulting in an interruption of the signaling cascade. In this study we probed the interaction of FPR with G protein in human neutrophils that were desensitized to various degrees. Human neutrophils were desensitized using the photoreactive agonist N-formyl-met-leu-phelys- N\(^\epsilon\)-[\(^{125}\)I]2(p-azidosalicylamido )ethyl-1 ,3 '-dithiopropionate (/MLFK-[\(^{125}\)I]ASD). The interaction if FPR with G protein was studied via a reconstitution assay and subsequent analysis of FPR-G protein complexes in sucrose density gradients. FPR-G protein complexes were reconstituted with solubilized FPR from partially and fully desensitized neutrophils with increasing concentrations of Gi purified from bovine brain. The respective EC\(_{50}\) values for reconstitution were similar to that determined for FPR from unstimulated neutrophils (Bommakanti RK et al., J Bio[ Chem 267: 757~7581, 1992). We conclude, therefore, that the affinity of the interaction of FPR with G protein is not affected by desensitization, consistent with the model of lateral segregation of FPR and G protein as a mechanism of desensitization.
Desensitization of N-fonnyl peptide chemoattractant receptors (FPR) in human neutrophils is thought to be achieved by lateral segregation of receptors and G proteins within the plane of the plasma membrane resulting in an interruption of the signalling cascade. Direct coupling of FPR to membrane skeletal actin appears to be the basis of this process~ however, the molecular mechanism is unknown. In this study we investigated the effect of energy depletion on formation of FPR-membrane skeleton complexes. In addition the effect of the protein kinase C inhibitor stauroporine and the phosphatase inhibitor okadaic acid on coupling of FPR to the membrane skeletonwas studied. Human neutrophils were desensitized using the photoreactive agonist N-formy1-met-leu-phe-1ys-N'[\(^{125}\)I]2(p-azidosalicylamido)ethyl-1,3'-dithiopropionate (fMLFK-[\(^{125}\)I]ASD) after ATP depletion with NaF or after incubation with the respective inhibitors. The interaction of FPR with the membrane skeleton was studied by Sedimentation of the membrane skeleton-associated receptors in sucrose density gradients. Energy depletion of the cells markedly inhibited the formation of FPR-membrane skeleton complexes. This does not appear tobe related to inhibition of protein phosphorylation due to ATP depletion because inhibition of protein kinases and phosphatases bad no significant effect on coupling of FPR to the membrane skeleton. We conclude, therefore, that coupling of FPR to the membrane skeleton is an energy,dependent process which does not appear to require modification of the receptor protein by phosphorylation.
Calc-silicate rocks occur as elliptical bands and boudins intimately interlayered with eclogites and high-pressure gneisses in the Munchberg gneiss complex of NE Bavaria. Core assemblages of the boudins consist of grossular-rich garnet, diopside, quartz, zoisite, clinozoisite, calcite, rutile and titanite. The polygonal granoblastic texture commonly displays mineral relics and reaction textures such as postkinematic grossular-rich garnet coronas. Reactions between these mineral phases have been modelled in the CaO-Al203-Si02-C02-H2 0 system with an internally consistent thermodynamic data base. High-pressure metamorphism in the calc-silicate rocks has been estimated at a minimum pressure of 31 kbar at a temperature of 630°C with X^oSQ.Gi. Small volumes of a C02-N2-rich fluid whose composition was buffered on a local scale were present at peak-metamorphic conditions. The P-T conditions for the onset of the amphibolite facies overprint are about 10 kbar at the same temperature. A'co., of the H20-rich fluid phase is regarded to have been <0.03 during amphibolite facies conditions. These P-T estimates are interpreted as representing different stages of recrystallization during isothermal decompression. The presence of multiple generations of mineral phases and the preservation of very high-pressure relics in single thin sections preclude pervasive post-peak metamorphic fluid flow as a cause of a re-equilibration within the calc-silicates. The preservation of eclogite facies, very high-pressure relics as well as amphibolite facies reactions textures in the presence of a fluid phase is in agreement with fast, tectonically driven unroofing of these rocks.
No abstract available
The aim of the present paper is to clarify the role of extreme order statistics in general statistical models. This is done within the general setup of statistical experiments in LeCam's sense. Under the assumption of monotone likelihood ratios, we prove that a sequence of experiments is asymptotically Gaussian if, and only if, a fixed number of extremes asymptotically does not contain any information. In other words: A fixed number of extremes asymptotically contains information iff the Poisson part of the limit experiment is non-trivial. Suggested by this result, we propose a new extreme value model given by local alternatives. The local structure is described by introducing the space of extreme value tangents. It turns out that under local alternatives a new class of extreme value distributions appears as limit distributions. Moreover, explicit representations of the Poisson limit experiments via Poisson point processes are found. As a concrete example nonparametric tests for Frechet type distributions against stochastically larger alternatives are treated. We find asymptotically optimal tests within certain threshold models.
In the present work the dimethylamino radical ( ( CH\(_3\)) \(_2\)N) and its protonated cation ( ( CH\(_3\))\(_2\)NH\(^+\)) are investigated by means of ab initio methods. The geometries of various conformations of both compounds are obtained with UMP2/6·31 G** calculations, while the hyperfine structure and its dependence on the geometry is studied using the MRD-Cl/B\(_K\) method. The two molecules are compared to study the inftuence of the protonation on geometry and hyperfine structure. The effects of the rotational barriers on the hyperfine structures of (CH\(_3\))\(_2\)N, (CH\(_3\)CH\(_2\))\(_2\)N and ( (CH\(_3\))\(_2\)CH)\(_2\)N will be discussed.
In 2 Untersuchungen mit 100 bzw. 88 Minderjährigen und 60 Erwachsenen werden Geschichten über drei - eine versehentliche, eine fahrlässige, eine absichtliche - Brandstiftungen mit bildlicher Unterstützung dargeboten. Durch Paarvergleiche zwischen bzw. Schätzurteile über die Geschichten wird ausgehend von der Wertungskomponente der Deliktsfähigkeit die Fähigkeit zur Unrechtserkenntnis für fahrlässige Schädigungen im Sinne der moralischen Differenzierungsfähigkeit untersucht, um einerseits die technische Durchführungsform und andererseits die einzelfalldiagnostische Auswertung nach psychometrischen bzw. varianzanalytischen Strategien zu erproben. Außerdem werden die Beziehungen der so erfaßten Wertungskomponenten zu Intelligenzuntertests geprüft. Aufgrund fehlender Korrelationen mit den Intelligenzmaßen empfiehlt sich die Anwendung des Verfahrens zur psychometrischen Begründung von Diagnosen zur zivilrechtlichen Verantwortlichkeit im Sinne des § 828 (2) BGB, damit sich die diesbezüglichen Diagnosen auch auf die Wertungskomponenten stützen können.
Der Beitrag beschäftigt sich mit Überlegungen zum Aufbau verhaltenssteuernder Strukturen. Er geht von dem Konzept de simpliziten Lernens aus, nach dem sich die Steuerung des Verhaltens, wenigstens unter bestimmten Bedingungen, unbewusst, aufmerksamkeitsunabhaengig und unwillkürlich an strukturelle Eigenschaften der Umgebung anpasst. Eine kritische Analyse einschlägiger Untersuchungen führt zu einer hypothetischen Lernstruktur, die es gestattet zu lernen, unter welchen Bedingungen welche Verhaltensakte zu welchen Konsequenzen führen. Der Lernprozess, so wird angenommen, wird in dieser Struktur von einem fundamentalen Beduerfnis nach sicherer Antizipierbarkeit von Verhaltenskonsequenzen getrieben. Eine Pilotstudie, die von diesen Annahmen ausgeht, wird ebenso diskutiert wie moegliche Anwendungen bei der Gestaltung von Trainingsprozessen im Sport.
An ordered NotI fragment map containing over 60 loci and encompassing approximately 17 Mb has been constructed for human chromosome band llpl5. Forty-two probes, including 11 NotI-linking cosmids, were subregionaUy mapped to llpl5 using a subset of the Jl-deletion hybrids. These and 23 other probes defining loci previously mapped to 11p15 were hybridized to genomic DNA digested with NotI and 5 other infrequently cleaving restriction enzymes and separated by pulsed-field gel electrophoresis. Thirty-nine distinct NotI fragments were detected encompassing approximately 85% of the estimated length of llp15. The predicted order of the gene loci used is cenMYODI- PTH-CALCA-ST5-RBTNI-HPX-HBB-RRMlTH/ INS!1GF2-H19-CTSD-MUC2-DRD4-HRAS-RNHtel. This map wiu allow higher resolution mapping of new Ilp15 markers, facilitate positional cloning of disease genes, and provide a framework for the physical mapping of llp15 in clone contigs.
During the past few years, interest in xenotransplantation of porcine islets of Langerhans for the future therapy of type I diabetes has Increased markedly. Therefore, we established a semiautomated digestion method for isolating islets from the porcine pancreas. However, although the isolation technique was standardized and collagenase of controlled quality was used, we were unable to attain high islet yields with a satisfactory degree of reproducibility. One hypothesis was that varying degrees of interference by donor pancreatic enzymes were responsible for this failure. The aim of this stUdy was to examine the kinetics of four types of enzymatic activity during the isolation procedure, as well as their effects on islet yield: collagenase, trypsin, neutral protease, and clostripaln. Our results indicate that while exogenous collagenase activity decreases slightly during the isolation procedure, the activity of the pancreas enzymes neutral protease and trypsin increases. In some cases, trypsin activity increases very strongly. A strong increase in trypsin activity correlates with poor islet yield, whereas low trypsin activity always correlates with high islet yield. Addition of the protease inhibitor Pefabloc to the isolation medium results in low trypsin activity and reproducible high islet yields.
Abstract: For isolating islets from the porcine pancreas, we established a semiautomated digestion method. Although the isolation technique was standardized and collagenase of controlled quality was used, until now the reproducibility of high islet yields was unsatisfactory. Our hypothesis was that pancreatic trypsin was responsible for this failure. The aim of this study was to investigate the effect of endogenous trypsin on islet yield. Our results demonstrate that a high trypsin level correlates with poor islet yield, whereas low trypsin activity always correlates with high islet yield. Specific inhibition of trypsin results in low trypsin activity and reproducible, high islet yields.
Isolation of Islets of Langerhans: Improvement of the Isolation Technique Using the Pig Model.
(1994)
During the last view years, interest in pancreatic islet transplantation for the cure of type I diabetes has increased markedly. A serious barrier to clinical islet transplantation is the isolation of a sufficient mass of viable and functional islets. We used a porcine islet isolation model to examine various parameters of the isolation procedure and to improve isolation technique.
The total cortical and striatal neurone and glial numbers were estimated in five cases of Huntington's disease (three males, two females) and five ageand sex-matched control cases. Serial 500-l-lm-thick gallocyanin-stained frontal sections through the left hemisphere were analysed using Cavalieri's principle for volume and the optical disector for cell density estimations. The average cortical neurone number of five controls (mean age 53±13 years, range 36-72 years) was 5.97x 109±320x 106 , the average number of small striatal neurones was 82 X 106± 15.8 X 106• The left striatum (caudatum, putamen, and accumbens) contained a mean of 273 X 106±53 X 106 glial cells (oligodendrocytes, astrocytes and unc1assifiable glial profiles). The mean cortical neurone number in Huntington's disease patients (mean age 49±14 years, range 36-75 years) was diminished by about 33 % to 3.99x109±218x106 nerve cells (P ::;:::: 0.012, MannWhitney V-test). The mean number of small striatal neurones decreased tremendously to 9.72 X 106 ± 3.64 X 106 (-88 % ). The decrease in total glial cells was less pronounced (193 X 106±26 X 106) but the mean glial index, the numerical ratio of glial cells per neurone, increased from 3.35 to 22.59 in Huntington's disease. Qualitatively, neuronal loss was most pronounced in supragranular layers of primary sensory areas (Brodmann's areae 3,1,2; area 17, area 41). Layer HIc pyramidal cells were preferentially lost in association areas of the temporal, frontal, and parietal lobes, whereas spared layer IV granule cells formed a conspicuous band between layer IH and V in these fields. Methodological issues are discussed in context with previous investigations and similarities and differences of laminar and lobar nerve cellloss in Huntington's disease are compared with nerve cell degent-ration in other neuropsychiatric diseases.
The total nerve cell numbers in the right and in the left human entorhinal areas have been calculated by volume estimations with the Cavalieri principle and by cell density determinations with the optical disector. Thick gallocyanin-stained serial frozen sections through the parahippocampal gyrus of 22 human subjects (10 female, 12 male) ranging from 18 to 86 years were analysed. The laminar composition of gallocyanin (Nissl)-stained sections could easily be compared with Braak's (1972, 1980) pigmentoarchitectonic study, and Braak's nomenclature of the entorhinal laminas was adopted. Cellsparse laminae dissecantes can more clearly be distinguished in Nissl than in aldehydefuchsin preparations. These cell-poor dissecantes, lamina dissecans extema (dis-ext), lamina dissecans 1 (dis-1) and lamina dissecans 2 (dis-2), were excluded from nerve cell nurober determinations. An exact delineation of the entorhinal area is indispensable for any kind of quantitative investigation. We have defined the entorhinal area by the presence of pre-alpha ceil clusters and the deeper layers of lamina principalis externa (pre-beta and gamma) separated from lamina principalis interna (pri) by lamina dissecans 1 (dis-1). The human entorhinal area is quantitatively characterized by a left-sided (asymmetric) higher pre-alpha cell number and an age-related nerve cell loss in pre as well as pri layers. At variance with other CNS cortical and subcortical structures, the neuronal number of the entorhinal area appears to decrease continuously from the earliest stages analysed, although a secular trend has to be considered. The asymmetry in pre-alpha cell number is discussed in the context of higher human mental capabilities, especially language.
Vorwort (Das Kind (1994) 16)
(1994)
No abstract available
Vorwort (Das Kind (1994) 15)
(1994)
No abstract available
In order to establish criteria for the Serodiagnosis of foamy virus infections we investigated the extent to which sera from iofected individuals of human and primate origin react with structural and non-structural virus proteins in immunoblot assays. Using lysates from infected cells as the source of virus antigen, antibodies were preferentially detected against the Gag proteins and the non-structural Bet protein. Both the Gag precursor molecules of 70 and 74K apparent M\(_r\) and the cytoplasmic 60K M\(_r\) Bet protein were found to be phosphorylated, the latter being synthesized in large amounts in infected cells. Rahbit antiserum raised against recombinant human foamy virus (HFV) Gag major capsid protein cross-reacted with foamy viruses of chimpanzee, gorilla, orang-utan, rhesus monkey and Mrican green monkey origin. This was reßected by a broad cross-reactivity of the respective monkey sera to the Gag proteins of the various foamy virus isolates. Cross-reactivity of antisera against the Bet protein was restricted to viruses from man and the great apes. Recombinant Gag and Bet proteins expressed in prokaryotes or in insect cells were readily recognized by foamy virus-positive primate sera. Screening serum samples from chimpanzees with HFV Gag and Bet proteins expressed by recombinant baculoviruses revealed that 18 out of 35 (52%) were positive for Gag antibodies. Of these, 13 (72 o/o) showed antiborlies against the Bet protein, indicating that Bet antigen is of value in sero1ogical screening for foamy virus infections.
DURING vertebrale development, many neurons depend for survival and differentiation on their target cells\(^{1-3}\). The best documented mediator of such a retrograde trophic action is the neurotrophin nerve growth factor (NGF)\(^1\). NGF and the other known members of tbe neurotrophin family, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT -3) and neurotrophin-4/5 (NT -4/5) are conserved as distinct genes over large evolutionary distances\(^{4 -6}\). Here we report the cloning of neurotrophin-6 (NT -6), a new member of this family from the teleost fish Xiphophorus. NT -6 distinguishes itself from the other known neurotrophins in that it is not found as a soluble protein in the medium of producing cells. The addition of heparin (but not chondroitin) effects the release of NT -6 from cell surface and extracellular matrix molecules. Recombinant purified NT -6 has a spectrum of actions similar to NGF on chick sympathetic and sensory neurons, albeit with a lower potency. NT -6 is expressed in tbe embryonie valvulla cerebelli; expression persists in some adult tissues. The interaction of NT-6 with heparin-binding molecuJes may modulate its action in the nervous system .
CATIO~IC drugs of different types and structures (antihistaminics, antiarrhythmics, sedatives, opiates, cytostatics and antibiotics, for example) are excreted in mammals by epithelial cells of the renal proximal tubules and by hepatocytes in the liver<sup>1-4</sup>. In the proximal tubules, two functionally disparate transport systems are involved which are localized in the basolateral and luminal plasma membrane and are different from the previously identified neuronal monoamine transporters and A TP-dependent multidrug exporting proteins<sup>1-3,5-12</sup>. Here we report the isolation of a complementary DNA from rat kidney that encodes a 556-amino-acid membrane protein, OCT1, which has the functional characteristics of organic cation uptake over the basolateral membrane of renal proximal tubules and of organic cation uptake into hepatocytes. OCTl is not homologous to any other known protein and is found in kidney, liver and intestine. As OCTl translocates hydrophobic and hydrophilic organic cations of different structures, it is considered to be a new prolotype of polyspecific transporters that are important for drug elimination.
Die vorliegende Arbeit ging zwei Hauptfragestellungen nach: (I) Inwiefern unterscheiden sich Experten in der Domäne Schach von Aussteigern aus der Expertisekarriere? (2) Wie verändern sich schachspezifische und generelle Gedächtnisparameter über einen Zeitraum von mehreren Jahren? Es wurden 27 Experten und Novizen mit einem durchschnittlichen Alter von knapp 12 Jahren zum ersten Meßzeitpunkt und von 16 Jahren zum zweiten Meßzeitpunkt untersucht. Die Aussteiger aus der Expertisekarriere zeigten bereits bei der Erstmessung schlechtere schachspezifische Gedächtnisleistungen als die übrigen Experten; die Annahme selektiver Aussteiger, die die Aussagekraft querschnittlicher Experten-Novizen-Vergleiche in Frage stellt, wird damit bestätigt. Sowohl für die Experten als auch für die Novizen zeigte sich ein Anstieg der schachspezifischen Gedächtnisleistung von der Erst- zur Zweitmessung. Während dafür bei Experten domänenspezifische Faktoren verantwortlich sein dürften, scheint dies bei Novizen auf die Entwicklung allgemeiner Gedächtnisparameter zurückzugehen.
The gene encoding the human homologue of the guinea pig uterine bombesm receptor [( 1992) Eur. J. Biochem. 208,405] was isolated from a genomic lambda library by the PCR/homology screening approach. The gene spans more than 4 kb and consists of 3 exons and 2 introns. The deduced amino acid sequence shows about 86% identity to that of guinea pig bombesin receptor. This subtype of bombesin receptor is expressed in the pregnant uterus and in two human tumour cell lines, T47D (ductal breast carcinoma) and A431 (epidermal carcinoma). PCR analysis of genomic DNA from human-mouse cell hybrids allows the cloned gene to be localized to the region q26q28 on chromosome X.
Homozygous deletions in Wilms' tumor DNA have been a key step in the identification and isolation of the WTI gene. Several additional loci are also postulated to contribute to Wilms' tumor formation. To assess the frequency of WTI alterations we have analyzed the WTI locus in a panel of 77 Wilms' tumors. Eight tumors showed evidence for large deletions of several hundred or thousand kilobasepairs of DNA, some of which were also cytogenetically detected. Additional intragenic mutations were detected using more sensitive SSCP analyses to scan all 10 WTI exons. Most of these result in premature stop codons or missense mutations that inactivate the remaining WTI allele. The overall frequency of WTI alterations detected with these methods is less than 15%. While some mutations may not be detectable with the methods employed, our results suggest that direct alterations of the WTI gene are present in only a small fraction of Wilms' tumors. Thus, mutations at other Wilms' tumor loci or disturbance of interactions between these genes likely play an important role in Wilms' tumor development.
No abstract available
A comparative ab initio study of the Si\(_2\)C\(_4\), Si\(_3\)C\(_3\), Si\(_4\)C\(_2\) clusters
(1994)
Various structural possibilities for the Si\(_2\)C\(_4\) and Si\(_4\)C\(_2\) clusters are investigated by employing a basis set of triple-zeta plus polarization quality; electron correlation is generally accounted for by second-order M0ller-Plesset and, in certain instances, by higher-order perturbation (CASPT2) approaches. The building-up principle recently suggested from an analysis of Si\(_3\)C\(_3\) clusters is found to be fully operative for Si\(_2\)C\(_4\) and Si\(_4\)C\(_2\) clusters. A comparison of the structure and stability of various geometrical arrangements in the series C\(_6\) , Si\(_2\)C\(_4\) , Si\(_3\)C\(_3\) , Si\(_4\)C\(_2\), and Si\(_6\) shows that linear and planar structures become rapidly less stable if carbons are replaced by silicons and that the three-dimensional bipyramidal forms become less favorable as soon as silicons are exchanged by carbons in the parent Si\(_6\) structure. The effects can be rationalized in qualitative terms based on differences in silicon and carbon bonding.
We have recently demonstrated that the frequency ofT cells expressing granzyme A is significantly higher in skin lesions and spleens of susceptible BALB/c mice compared with resistant C57BL/6 mice infected with Leishmania major, a cause of human cutaneous leishmaniasis. In the present study, we have performed in vitro studies to characterize the subpopulation, the antigen responsiveness and the lymphokine production pattern of granzyme A-expressing T cells in L. major-infected mice. Using a limiting dilution system for functional analysis of selected T cells at the clonallevel, we could show that granzyme A activity in infected BALB/c mice can be assigned to L. major-reactive CD4\(^+\) T cells secreting interleukin-2 (IL-2) and IL-4. Granzyme A production was most pronounced in the early phase of infection. On the other hand, granzyme A expression could not be detected in C57BL/6-derived T cells responding to L. major. The da ta support the suggestion that granzyme A is produced by L. major-responsive CD4\(^+\) T cells facilitating lesion formation and the dissemination of infection.
Assoziationen von Ameisen mit Pflanzen (und oft noch mit pflanzensaugenden Insekten als drittem Partner) dürften eine Ursache des Artenreichtums und der hohen Abundanzen tropischer Formicidae sein. Die von den Ameisen genutzten Pflanzen bieten entweder Nahrung an, über extraflorale Nektarien und/oder Nährkörperchen, oder aber - bei den eigentlichen Myrmekophyten - Nistraum und z.T. auch Nahrung. Diese Beziehungen zeichnen sich durch unterschiedliche Nutzungsweisen und Nutzungsintensitäten und damit stark differierende Abhängigkeit der Partner voneinander aus. Ein besonders breites Spektrum von Ameisen-Pflanzen-Assoziationen finden wir in der paläotropischen Baumgattung Macaranga (Euphorbiaceae), die sich daher als Modellsystem für vergleichende Untersuchungen hervorragend eignet. Die Grundfrage unserer Untersuchungen an diesem System lautet: Verläuft aufgrund der ausgeprägt mosaikartigen Verteilung der von den myrmekophilen Pflanzen angebotenen Nahrungs- und Nistraumressourcen die Neu- und Wiederbesiedlung von Habitaten durch die Ameisen in Form von Zufallsprozessen? Oder werden, im Gegenteil, durch diesen Umstand Spezialisierungen seitens der Ameisen gefördert und die Zusammensetzung der Lebensgemeinschaften dadurch stärker deterministisch geprägt? Unsere bisherigen Untersuchungen zeigen, daß beide Prinzipien wirken. Bei der alleinigen Nutzung von Nahrungsressourcen fehlen spezialisierte Beziehungen weitgehend und stochastische Ereignisse dürften sehr häufig die Pflanzen-Ameisen-Assoziation bestimmen. Bei den eigentlichen Myrmekophyten hingegen ist die Auswahl der assozierten Ameisen viel stärker determiniert, ganz besonders dann, wenn der Wohnraum, den die Pflanze offeriert, nur durch aktives Öffnen seitens der Ameisen erschlossen werden kann.
The pioneer tree Macaranga in SE Asia has developed manyfold associations with ants. The genus comprises all stages of interaction with ants, from facultative relationships to obligate myrmecophytes. Only myrmecophytic Macaranga offer nesting space for ants and are associated with a specific ant partner. The nonmyrmecophytic species are visited by a variety of different ant species which are attracted by extrafloral nectaries (EFN) and food bodies. Transitional Macaranga species like M. hosei are colonized later in their development due to their stem structure. Before the colonization by their specific Crematogaster partner the young plants are visited by different ant species attracted by EFN. These nectaries are reduced and food body production starts as soon as colonization becomes possible. We demonstrated earlier that obligate ant partners can protect their Macaranga plants against herbivore damage and vine cover. In this study we focused on nonspecific interactions and studied M. tanarius and M. hosei, representing a non-myrmecophyte and a transitional species respectively. In ant exclusion experiments both M. tanarius and M. hosei suffered significantly higher mean leaf damage than controls, 37% versus 6% in M. hosei, 16% versus 7% in M. tanarius. M. tanarius offers both EFN and food bodies so that tests for different effects of these two food rewards could be conducted. Plants with food bodies removed but with EFN remaining had the lowest mean increase of herbivore damage of all experimental groups. Main herbivores on M. hosei were mites and caterpillars. Many M. tanarius plants were infested by a shootborer. Both Macaranga species were visited by various ant species. Crematogaster spp. being the most abundant. We found no evidence for any specific relationships. The results of this study strongly support the hypothesis that non-specific, facultative associations with ants can be advantageous for Macaranga plants. Food bodies appear to have lower attractive value for opportunistic ants than EFN and may require a specific dietary adaptation. This is also indicated by the fact that food body production in the transitional M. hosei does not start before stem structure allows a colonization by the obligate Crematogaster species. M. hosei thus benefits from facultative association with a variety of ants until it produces its first domatia and can be colonized by its obligate mutualist.
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The male-polymorphic poeciliid fish, Limia perugiae, a small teleostean endemic to the southeast of the Caribbean island Hispafiola, consists of three male size morphs with uniform females. Large males differentiate at a size va:rying between 25 and 38 mm; intermediate males, between 21 and 25 mm. Under competition, !arge males exhibit an elaborate courtship display, whereas small males show only a sneak-chase behavior. Intermediate males adapt their tactics to the respective competitors. However, all malemorphs can switch from courtship display to sneak-chase behavior. In large mating groups with four males of different size and five or six virgin females, large dominant a-males as weil as small subordinate \(\delta\)-males did not produce any offspring. Unexpectedly, all progeny were sired exclusively by the intemediate subordinate ß- and \(\gamma\)-males. Breeding experiments with the three male morphs can best be explained by a model of Y -linked genes for small and !arge size which are both suspended by the activity of an autosomal recessive repressor responsible for the development of intermediate males. The dominant allele of the recessive repressor, in either its homoorits heterozygous state, activates the Y-chromosomal genes for !arge or small size, respectively. Accordingly, intermediate males may produce male offspring of all size classes, depending on the presence of either the Y-linked gene or the autosomal repressor.
A reliable prediction of the isotropic hyperfine coupling constant A\(_{iso}\) is still a difficult task for ab initio calculations. In previous studies, the configuration selected multireference configuration interaction method in combination with perturbation theory to correct the wave function (MRCI/ B\(_K\)) yielded accurate isotropic hyperfine coupling constants very economically. The present study gives a detailed analysis of the MRCI/ B\(_K\) method based on the X\(^2 \pi\) state of CH as a test case. Furthermore, a comparison to various other methods such as Maller-Ptesset perturbation theory and the coupled cluster approach is made. The success of the MRCI/ B\(_K\) method in predicting isotropic hyperfine coupling constants is explained in terms of the inßuence of higher than double excitations.
The structural properties of HgSe grown by molecular beam epitaxy (MBE) are investigated for different lattice mismatches to the substrate and various growth conditions. The growth rate is shown to depend strongly on the growth temperature above lOO°C as well as on the Hg/Se flux ratio. It has been found that the crystalline perfection and the electrical properties are mainly determined by the layer thickness, especially for the growth on highly lattice mismatched substrates. Changes in the surface morphology are related to growth parameters. Differences between the electrical behavior of MBE-grown and bulk HgSe are discussed. The electrical properties of HgSe contacts on p-ZnSe are investigated as a function of different annealing procedures.
Measles virus is a highly contagious virus causing acute and persistent diseases in man, the receptor of which is still not weil characterized. We have isolated a monoclonal antibody (mAb), designated mAb 119, which specifically inhibits measles virus infection of susceptible celllines in a dosa-dependent manner. This antibody precipitates a protein with an apparent molecular mass of 75 kDa from 1251 surface-labeled cells and its epitope is present on human peripheral blood mononuclear cells, human celllines, and the African green monkey cellline Vero. Affinity chromatography of detergent-solubilized cell membrane proteins over a Sepharose column with covalently bound mAb 119 led to the partial purification of the 75-kOa protein. Preincubation of measles virus with this affinity-purified protein inhibited measles virus infection dose dependently. Aminoacid microseq,uencing of this protein revealed its identity with the human membrane-organizing extension spike protein moesin, a protein intra- and extracellularly associated with the plasma membrane of cells. Subsequently, an antibody raised against purified moesin (mAb 38/87) was also found to specifically inhibit measles virus infection of susceptible cells and confirmed our data obtained with mAb 119. Our data suggest that moesin is acting as a receptor for measles virus.
Receptor binding properties of four-helix-bundle growth factors deduced from electrostatic analysis
(1994)
Hormones of the hematopoietin class mediate signal transduction by binding to specific transmembrane receptors. Structural data show that the human growth hormone (hGH) forms a complex with a homodimeric receptor and that hGH is a member of a class of hematopoietins possessing an antiparallel 4-a-helix bundle fold. Mutagenesis experiments suggest that electrostatic interactions may have an important influence on hormonereceptor recognition. In order to examine the specificity of hormone-receptor complexation, an analysis was made of the electrostatic potentials of hGH, interleukin-2 (IL-2), interleukin-4 (IL-4), granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and the hGH and IL-4 receptors. The binding surfaces of hGH and its receptor, and of IL-4 and its receptor, show complementary electrostatic potentials. The potentials of the hGH and its receptor display approximately 2-fold rotational symmetry because the receptor subunits are identical. In contrast, the potentials of GM-CSF and IL-2 Iack such symmetry, consistent with their known high affinity for hetero-oligomeric receptors. Analysis of the electrostatic potentials supports a recently proposed hetero-oligomeric model for a high-affinity IL-4 receptor and suggests a possible new receptor binding mode for G-CSF; it also provides valuable information for guiding structural and mutagenesis studies of signal-transducing proteins and their receptors.
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Heritabilities and repeatabilities are presented for various behavioural attributes affecting foraging performance and fitness in Aquarius (Gerris) remigis (Heteroptera: Gerridae) females. These behavioural attributes were patch choice, foraging success, capture accuracy, and measures of mobility, activity, skittishness and aggressiveness. Most heritabilities were not significantly different from zero, which may be related to the low sampIe size. Conclusions as to the potential of direct selection on behaviour in this species were consequently limited. In contrast, with a few exceptions (capture accuracy, foraging success), most repeatabilities were significant and at times high (range=O'22-O'79), indicating consistent, stereotypical individual behaviour. Tbe Iife history or reproductive state of the daughter generation individuals signifieantly affected the magnitude of the repeatabilities as weil as the mean values of many of the variables (notably mobility and aggressiveness), the latter in a manner consistent with field observations. This indicates that the state of the organism affects the general environmental variance, thus contributing to the discrepancies between the repeatabilities and the heritabilities obtained. It is suggested that common physiological proeesses (e.g. hormones) may underlie several of the behavioural attributes examined, resulting in possible pleiotropie effects and eonstraints on selection in a heterogeneous environment. It is further suggested that field studies of selection on behavioural attributes may be a more fruitful approach in this species, whose suitability for genetic analysis is limited.
143 9- and 10-year-oId children were classified into high- and Jow-IQ groups and given 4 different sort/recall lists (baseline, training, near [immediate] extension, far [l-week] extension) to assess training and extension of an organizational memory strategy. All children received categorized items of moderate typicality for Phases 1, 3, and 4. For Phase 2, children were assigned to either a training or control group, with half of the children in each group receiving category typical items and the others category atypical items. Levels of recall, sorting, and clustering were greater in Phase 2 for high-IQ children, for the typical lists, and for trained children. Both the high- and low-IQ children trained with typical items continued to show high levels of recall on the near extension phase. No group of subjects maintained high levels of recall after 1 week, although levels of sorting and/or clustering on the extension trials remained high for all groups of subjects except the low-IQ control children. This latter pattern (elevated sorting/clustering with low levels of recall) is an indication of a utilization deficiency, a phase in strategy development when children use a strategy but gain little or no benefit n performance. The results provide evidence for IQ, training, and material effects in the demonstration of a utilization deficiency.
Highly reactive methanesulfonates (mesylates, ROMs) have been prepared from 1-phenylethanol. cyclohex-2-en-1-ol, diphenylmethanol and p-methoxybenzyl alcohol by treatment with methanesulfonyl chloride and triethylamine in dichloro- or trichloro-methane at - 20 to 0 °C. The mesylates. characterised in solution by \(^1\)H and \(^{13}\)C NMR at -20 °C, were obtained in satisfactory purity (ca. 95%) in cold solutions but they decomposed by reaction with chloride, triethylamine or the parent alcohol. Rate constants for solvolyses in aqueous acetone and aqueous ethanol have been determined by a fast response conductimetric method. Product selectivities for solvolyses of pmethoxybenzyl mesylate in aqueous ethanol and methanol at 0 °C have been determined by HPLC. From additional new or Iiterature kinetic data for solvolyses of corresponding bromides. chlorides and p-nitrobenzoates (OPNB). Br/CI. OMs/Br and OMs/OPNB rate ratios were calculated; the results are consistent with electronic effects stabilising the carbocationic transition states and increasing OMs/Br rate ratios for these SN 1 solvolyses; none of the evidence supports a geminal electronic effect on Br/CI rate ratios (e.g. caused by stabilisation of the initial state in pmethoxybenzyl chloride). Steric effects on ester /halide rate ratios for solvolyses of tertiary substrates are confirmed. Relative rates over a 10\(^{16}\) range for ester and halide leaving groups are evaluated for solvolyses of 1-phenylethyl substrates in 80% ethanol-water. updating previous work by Noyce et al. (1972).
In einem Kollektiv von 130 MR-tomographisch untersuchten psychiatrischen Patienten (axiale T2-SE-Sequenz) wurden Zahl und räumliche Verteilung von hyperintensen Marklagerläsionen ("white matter lesions"; WM L) erfaßt und die Ventricle-to-brain-Ratio (VBR) bestimmt. Eine Konfigurationsfrequenzanalyse auf der Grundlage der räumlichen WMLVerteilung erlaubte die Abgrenzung von vier Patientengruppen: 1. keine WML (n = 35), 2. WML rechts frontotemporal (n = 23), 3. WML bifrontal (n = 12), 4. WML ubiquitär (n = 16). Die während 3 Jahren beobachteten psychopathologischen Symptome dieser Patienten wurden retrospektiv nach dem AMDP-Systemdokumentiert. In der Gruppe mit ubiquitären WML überwogen organisch-psychopathologische Ttems, die VER war größer als in den anderen Gruppen (ANOVA;p < 0,001). Die räumliche W M L- Verteilung erklärte 10,24 % der Gesamtvarianz psychopathologischer M erkmalsverteilung in den Gruppen. Das Patientenalter (MANCOVA; p < 0,021), nicht aber die VER hattesignifikanten Einfluß auf das psychopathologische Symptomprofil. Nach Ausblendung der Patientengruppe mit ubiquitären WMLblieb der Einfluß der WML-Verteilung auf die psychopathologische Symptomatiksignifikantc (p <0,05). Bifrontale WML waren mit Denkstörung, rechts frontotemporale WML mit affektiven Symptomen assoziiert. Die Befunde sprechen für einen Einfluß der räumlichen Verteilung unspezifischer Marklagerläsionen auf die psychopathologische Symptomatik.
46 Patienten mit affektiven Erkrankungen und pathologischem CT wurden untersucht (Infarkt: 22, Kontusion: 6, Leukoaraiose: 11, frühkindlicher Hirnschaden: 7). Monopolar Depressive (DSMIII- R; MD) zeigten oft Leukoaraiose, Infarkte waren mit MD, Kontusionen und frühkindliche Schäden mit bipolarer Erkrankung assoziiert (BP; ANCOV A, p< .1). Kortikale Läsionen waren bei BP häufiger, jedoch fehlten signifikante Effekte von Läsionsort oder -zeitpunkt auf die Polarität der Erkrankung (ANOV A). Bei einigen Infarktpatienten kam es zur Verlaufsänderung (Chronifizierung, Bipolarität) nach Infarkt, alle Post-Infarkt-Ersterkrankungen waren bipolar.