bluuebunny/crossref_metadata_2025_split huggingface dataset:
Na+/H+ exchange subtype 1 inhibition during extracellular acidification and hypoxia in glioma cells
Authors: Glunde Kristine , Düßmann Heiko , Juretschke Hans‐Paul , Leibfritz Dieter 
Published: March 2003

AbstractLactacidosis is a common feature of ischaemic brain tissue, but its role in ischaemic neuropathology is still not fully understood. Na+/H+ exchange, a mechanism involved in the regulation of intracellular pH (pHi), is activated by low pHi. The role of Na+/H+ exchange subtype 1 was investigated during extracellular acidification and subsequent pH recovery in the absence and presence of (4‐isopropyl‐3‐methylsulphonyl‐benzoyl)‐guanidine methanesulfonate (HOE642, Cariporid), a new selective and powerful inhibitor of the Na+/H+ exchanger subtype 1 (NHE‐1). It was compared for normoxia and hypoxia in two glioma cell lines (C6 and F98). pHi was monitored by fluorescence spectroscopy using the intracellularly␣trapped␣pH‐sensitive dye 2′,7′‐bis(carboxyethyl)‐5(6)‐carboxyfluorescein (BCECF). Alterations in glial cell metabolism were characterized using high‐resolution 1H, 13C and 31P NMR spectroscopy of perchloric acid extracts. NHE‐1 contributed to glial pH regulation, especially at pathologically low pHi values. NHE‐1 inhibition with HOE642 during acidification caused exacerbated metabolic disorders which were prolonged during extracellular pH recovery. However, NHE‐1 inhibition during hypoxia protected the energy state of glial cells.
Locally synthesized angiotensin modulates pineal melatonin generation
Authors: Baltatu Ovidiu , Afeche Solange Castro , Santos Sabrina Heloísa José dos , Campos Luciana Aparecida , Barbosa Roseli , Michelini Lisete C. , Bader Michael , Cipolla‐Neto José 
Published: March 2003

Abstract+We aimed to study the mechanisms and the significance of the influence exerted by the renin‐angiotensin system (RAS) on the pineal melatonin production. Pineal melatonin and other indoles were determined by HPLC with electrochemical detection after angiotensin AT1‐receptor blockade with Losartan in vivo or in cultured glands. N‐acetyltransferase (NAT) activity was radiometricaly measured. To test the in vivo relevance of the local RAS, pineal melatonin and its indole precursors were determined in transgenic rats with inhibited production of angiotensinogen exclusively in astrocytes, TGR(ASrAOGEN). Tryptophan hydroxylase (TPH) and NAT mRNA levels were determined by real‐time RT–PCR. Pineal melatonin content was significantly decreased by AT1‐receptor blockade in vivo, in cultured glands and in TGR(ASrAOGEN) (35%, 32.4% and 17.5% from control, respectively). Losartan produced a significant decrease of pineal 5‐hydroxytryptophan, serotonin, 5‐hydroxyindole acetic acid and N‐acetylserotonin in pineal cultures. Also, the pineal content of the precursor indoles in TGR(ASrAOGEN) rats was significantly lowered. The reduction of 5‐hydroxytryptophan levels by 33–75% in both in vivo and in vitro studies suggests a decreased activity of TPH. Moreover, the TPH mRNA levels in TGR(ASrAOGEN) rats were significantly lower than control rats. On the other hand, NAT activity was unaffected by Losartan in pineal culture and its expression was not significantly different from control in TGR(ASrAOGEN) rats. Our results demonstrate that a local pineal RAS exerts a tonic modulation of indole synthesis by influencing the activity of TPH via AT1‐receptors.
Geldanamycin specifically modulates thrombin‐mediated morphological changes in mouse neuroblasts
Authors: Pai Karnire Sadashiva , Cunningham Dennis D. 
Published: March 2003

AbstractRegulation of neuronal morphology and extension of cell processes are required for normal synaptic connections and signaling. Thrombin, a serine protease, regulates neuronal morphological changes by activating protease activated receptor‐1 (PAR‐1), a seven‐transmembrane G protein‐coupled receptor. Thrombin‐mediated morphological changes precede its diverse action on neurons, and the drugs that regulate these morphological changes have important therapeutic implications. The present study was carried out to evaluate the role of geldanamycin, a specific inhibitor of Hsp90 on thrombin‐induced regulation of neuronal morphology. Incubation of mouse neuroblasts (NB2a) with geldanamycin prevented thrombin‐mediated neurite retraction in a dose‐dependent manner. Geldanamycin also blocked thrombin‐induced activation of RhoA, a small GTP binding protein involved in the cytoskeletal signaling. To determine the specificity of geldanamycin action, its effect on lysophosphatidic acid (LPA)‐induced morphological changes was examined. Geldanamycin did not have any effect on LPA‐induced neurite retraction and RhoA activation indicating a specific role for this drug in the regulation of thrombin‐mediated morphological changes.
Subunit specificity and interaction domain between GABAA receptor‐associated protein (GABARAP) and GABAA receptors
Authors: Nymann‐Andersen Jesper , Wang Hongbing , Chen Li , Kittler Josef T. , Moss Stephen J. , Olsen Richard W. 
Published: March 2003

AbstractGABARAP (GABAA receptor‐associated protein) interacts with both microtubules and GABAA receptors in vitro and in␣vivo and is capable of modulating receptor channel kinetics. In this study, we use the intracellular loop of 15 GABAA receptor subunits to show that the interaction between GABARAP and GABAA receptor is specific for the gamma subunits. Pharmacological characterization of proteins purified by GABARAP affinity column indicates that native GABAA receptors interact with GABARAP. Quantitative yeast two‐hybrid assays were used to identify the interaction domain in the γ2 subunit for GABARAP binding, and to identify the interaction domain in GABARAP for GABAA receptor binding. A peptide corresponding to the GABARAP interaction domain in the γ2 subunit was used to inhibit the interaction between GABARAP and the γ2 subunit. In addition, the ability of GABARAP to promote cluster formation of recombinant receptors expressed in QT‐6 fibroblasts was inhibited by a membrane‐permeable form of this peptide in a time‐dependent manner. The establishment of a model for GABARAP‐induced clustering of GABAA receptors in living cells and the identification of subunit specificity and interaction domains in the interaction between GABARAP and GABAA receptors is a step in dissecting the function of GABARAP in GABAA receptor clustering and/or targeting.
Non‐homologous DNA end joining in the mature rat brain
Authors: Ren Keqin , De Ortiz Sandra Peña 
Published: March 2003

AbstractRecent evidence suggests that DNA double strand breaks (DSBs) are introduced in neurons during the course of normal development, and that repair of such DSBs is essential for neuronal survival. Here we describe a non‐homologous DNA end joining (NHEJ) system in the adult rat brain that may be used to repair DNA DSBs. In the brain NHEJ system, blunt DNA ends are joined with lower efficiency than cohesive or non‐matching protruding ends. Moreover, brain NHEJ is blocked by DNA ligase inhibitors or by dATP and can occur in the presence or absence of exogenously added ATP. Comparison of NHEJ activities in several tissues showed that brain and testis share similar mechanisms for DNA end joining, whereas the activity in thymus seems to utilize different mechanisms than in the nervous system. The developmental profile of brain NHEJ showed increasing levels of activity after birth, peaking at postnatal day 12 and then gradually decreasing along with age. Brain distribution analysis in adult animals showed that NHEJ activity is differentially distributed among different regions. We suggest that the DNA NHEJ system may be utilized in the postnatal brain for the repair of DNA double strand breaks introduced within the genome in the postnatal brain.
Metabolism of reduced and inorganic sulphur in pea cotyledons and distribution into developing seedlings
Authors: Herschbach Cornelia , Pilch Birgit , Tausz Michael , Rennenberg Heinz , Grill Dieter 
Published: March 2003

Summary

Sulphur export and redistribution from the cotyledons of pea (Pisum sativum) seedlings was investigated to determine the role of cotyledons as a sulphur source during root–shoot axis development.
Thiols and sulphate were analysed using standard biochemical techniques, and 35S fed to cotyledons by injection.
After 35S‐cysteine injection, c. 50% of the labelled S in the cotyledon was metabolized to 35S‐sulphate. This reaction was partly inhibited by aminooxyacetic acid, an inhibitor of cysteine‐desulfhydrase. After 35S‐sulphate application, c. 1% of the radiolabel was found in cysteine and glutathione in the cotyledon. After 2 h, c. 20% of the 35S was transported into the root–shoot axis independently of whether 35S‐sulphate or 35S‐cysteine was injected into the cotyledon. After 4 h, 40% of 35S was found outside the cotyledon.
Cotyledons of pea seedlings are capable of sulphate assimilation and cysteine degradation. Both sulphate and reduced sulphur were allocated from the cotyledons to the developing tissues of the pea seedlings.
Stomatal control by chemical signalling and the exploitation of this mechanism to increase water use efficiency in agriculture
Authors: Davies William J. , Wilkinson Sally , Loveys Brian 
Published: March 2003

SummaryStomatal behaviour of plants in drying soil can be regulated by (long distance) chemical signals that provide the shoot with some measure of water availability. Although much emphasis has been placed on the plant hormone abscisic acid (ABA) as a central component of the signalling process, soil drying will modify the delivery to the shoot of a range of potential chemical signals. Here we consider the role that changes in the xylem sap pH might play in determining the access that ABA has to sites of action on the guard cells. We also show how redistribution of inorganic ions between different compartments in the leaf (localized chemical signalling) can provide sensitive control of stomata and water loss in response to potentially damaging changes in leaf temperature. Partial root zone drying is an irrigation technique that has been developed to allow exploitation of the plant’s long distance signalling system. When the system is optimized, stomatal behaviour, shoot water status and leaf growth can be regulated such that water use efficiency (fruit yield/water used) can be significantly increased. We show how an understanding of the drought stress physiology of the whole plant can lead to substantial saving of irrigation water in agriculture.
Determination of Stress Concentration Factors for Holes in Cylinders Using Thermoelastic Stress Analysis
Authors: Quinn S. , Dulieu‐Barton J. M. 
Published: March 2003

AbstractThermoelastic stress analysis is used to obtain the stress concentration factors (SCFs) from a variety of circular holes in cylinders. The cylinders are loaded in uniaxial tension, uniaxial compression and a combination of bending and compression. Firstly, radial holes are investigated and the results from the thermoelastic data obtained by the SPATE equipment are compared with previous experimental and numerical work. SCFs are then obtained from offset, oblique and offset–oblique holes using the Deltatherm system. The effect of hole obliquity and direction of applied load relative to the hole geometry are discussed in detail. Finally, the results from the cylinders are compared with predictions of the SCFs in cylinders from a previous study of oblique holes in flat plates.
Isolation of human scFv antibody fragments against ABO blood group antigens from a phage display library
Authors: Santos‐Esteban E. , Curiel‐Quesada E. 
Published: March 2003

Background and ObjectivesPhage display has proven very useful for the isolation of antibodies against a number of antigens. We used this technology to isolate scFv antibody fragments against A and B red blood cell antigens.Materials and MethodsPhages from a phage display library were selected using unmodified red blood cells as a source of antigen. Bound phages were absorbed onto cells lacking the antigen of interest and used to infect Escherichia coli cells. Phages were rescued and assayed for specificity by enzyme‐linked immunosorbent assay (ELISA).ResultsAfter several rounds of panning and subtraction on red blood cells, one anti‐A and one anti‐B human scFv antibody fragments were isolated.ConclusionIsolation of anti‐A and anti‐B scFv antibody fragments on whole cells is an alternative method of obtaining antibodies against native cell‐surface antigens.
Human platelet antigen‐1a antibodies induce the release of the chemokine RANTES from human platelets
Authors: Dettke M. , Dreer M. , Höcker P. , Panzer S. 
Published: March 2003

Background and ObjectiveBinding of human platelet antigen‐1a (HPA‐1a)‐specific antibodies to target platelets can trigger platelet activation and mediator release. Here we tested the effect of HPA‐1a antibody‐containing sera on platelet release of the chemokine RANTES (regulated on activation, normal, T‐cell expressed, and presumably secreted) in vitro.Patients and MethodsHPA‐1a‐containing sera obtained from 11 mothers delivered of an infant with neonatal alloimmune thrombocytopenia (NAIT) and from six patients with post‐transfusion purpura (PTP) were incubated with HPA‐1a/a target platelets. Antibody‐induced release of soluble RANTES was determined by enzyme‐linked immunosorbent assay (ELISA).ResultsA significant release of soluble RANTES was induced by four out of the 17 sera. Two out of the four reactive sera were obtained from mothers who were delivered of a baby with NAIT and the remaining two sera were from patients with PTP. Chemokine release was specific for binding of anti‐HPA‐1a to the platelet membrane, as none of the reactive sera induced the release of soluble RANTES when incubated with HPA‐1b/b platelets. The blockade of platelet‐expressed Fc gamma receptor type II (FcγRII) inhibited anti‐HPA‐1a‐mediated RANTES release when incubated with the reactive sera of patients with NAIT, but not when platelets were incubated with sera of patients with PTP.ConclusionOur findings suggest that anti‐HPA‐1a antibody‐induced release of platelet‐derived RANTES can play a role in adverse reactions in alloimmunized patients.
Hydrothermal alteration of late‐ to post‐tectonic Lyon Mountain Granitic Gneiss, Adirondack Mountains, New York: Origin of quartz–sillimanite segregations, quartz–albite lithologies, and associated Kiruna‐type low‐Ti Fe‐oxide deposits
Authors: Mclelland J. , Morrison J. , Selleck B. , Cunningham B. , Olson C. , Schmidt K. 
Published: March 2003

AbstractQuartz–sillimanite segregations, quartz–albite lithologies (Ab95–98), and Kiruna‐type low‐Ti iron‐oxide deposits are associated with late‐ to post‐tectonic (c. 1055 Ma) leucogranites of Lyon Mountain Gneiss (LMG) in the Adirondack Mountains, New York State. Most recent interpretations of these controversial features, which are global in occurrence, favour hydrothermal origins in agreement with results presented here.Field relations document that quartz–sillimanite veins and nodules cut, and therefore post‐date, emplacement of host LMG leucogranites. Veins occur in oriented fracture networks, and aligned trains of nodules are interpreted as disrupted early veins. Late dykes of leucogranite cut veins and nodules demonstrating formation prior to terminal magmatism. Veins and nodules consist of sillimanite surrounded by quartz that commonly embays wall‐rock feldspar indicating leaching of Na and K from LMG feldspar by acidic hydrothermal fluids. Subsequent, and repeated, ductile flow disrupted earlier veins into nodular fragments but produced little grain shape fabric.Geochemical and petrographic studies of quartz–albite rock indicate that it formed through metasomatic replacement (albitization) of LMG microperthite by sodic hydrothermal fluids that resulted in diagnostic checkerboard albite. Low‐Ti iron‐oxide ores are commonly associated with the quartz–albite sub‐unit, and it is proposed that hydrothermal fluids related to albitization transported Fe as well. The regional extent of sodic alteration suggests large quantities of surface‐derived hydrothermal fluids. Fluid inclusion and oxygen isotope data are consistent with high temperature, regionally extensive fluids consisting primarily of evolved surface‐derived brines enriched in Na and Cl. Quartz–sillimanite veins and nodules, which are significantly more localised phenomena and require acidic fluids, were most likely formed from local magmatic fluids in the crystallizing carapaces of LMG plutons.
Occurrence of calcite in Sanbagawa pelitic schists: implications for the formation of garnet, rutile, oligoclase, biotite and hornblende
Authors: Goto A. , Banno S. , Higashino T. , Sakai C. 
Published: March 2003

AbstractThe frequency of occurrence of minerals in 1876 samples of Sanbagawa pelitic schist in central Shikoku is summarized on the basis of microscopic observation accompanied, in part, by use of an electron microprobe. All samples contain quartz, plagioclase, phengite, chlorite and graphite. More than 90% of samples contain clinozoisite, titanite and apatite. Garnet is present in 95% of samples from the garnet zone, and biotite is present in 64% of samples from the albite‐biotite zone. Calcite is found in about 40% of samples of the pelitic schist collected from outcrop, but occurs in 95% of the pelitic schist from drill cores. Calcite was apparently ubiquitous in the pelitic schist during the Sanbagawa metamorphism, but must have been dissolved recently by the action of surface or ground water. The mineral assemblages of the Sanbagawa pelitic schist have to be analyzed in the system with excess calcite, quartz, albite (or oligoclase), clinozoisite, graphite and fluid that is composed mainly of H2O, CO2 and CH4. In the presence of calcite, reactions that produce garnet, rutile, oligoclase, biotite and hornblende, some of which define isograds of the metamorphic belt, should be written as mixed volatile equilibria that tend to take place at lower temperature than the dehydration reactions that have been proposed. The presence of calcite in pelitic schist suggests that fluid composition is a variable as important in determining mineral assemblages as pressure and temperature. Thus Ca‐bearing phases must be taken into account to analyze the phase relations of calcite‐bearing pelitic schist, even if CaO content of Sanbagawa pelitic schist is low. As calcite is a common phase, the mineral assemblages of the biotite zone pelitic schist may contravene the mineralogical phase rule and warrant further study.
Relationships of extant lower Brachycera (Diptera): a quantitative synthesis of morphological characters
Authors: Yeates David K. 
Published: March 2003

With over 80 000 described species, Brachycera represent one of the most diverse clades of organisms with a Mesozoic origin. Larvae of the majority of early lineages are detritivores or carnivores. However, Brachycera are ecologically innovative and they now employ a diverse range of feeding strategies. Brachyceran relationships have been the subject of numerous qualitative analyses using morphological characters. These analyses are often based on characters from one or a few character systems and general agreement on relationships has been elusive. In order to understand the evolution of basal brachyceran lineages, 101 discrete morphological characters were scored and compiled into a single data set. Terminals were scored at the family level, and the data set includes characters from larvae, pupae and adults, internal and external morphology, and male and female terminalia. The results show that all infraorders of Brachycera are monophyletic, but there is little evidence for relationships between the infraorders. Stratiomyomorpha, Tabanomorpha, and Xylophagomorpha together form the sister group to Muscomorpha. Xylophagomorpha and Tabanomorpha are sister groups. Within Muscomorpha, the paraphyletic Nemestrinoidea form the two most basal lineages. There is weak evidence for the monophyly of Asiloidea, and Hilarimorphidae appear to be more closely related to Eremoneura than other muscomorphs. Apsilocephalidae, Scenopinidae and Therevidae form a clade of Asiloidea. This phylogenetic evidence is consistent with the contemporaneous differentiation of the main brachyceran lineages in the early Jurassic. The first major radiation of Muscomorpha were asiloids and they may have diversified in response to the radiation of angiosperms in the early Cretaceous.
Phylogeny of the Hymenoptera: a reanalysis of the Ronquist et al. (1999) reanalysis, emphasizing wing venation and apocritan relationships
Authors: Sharkey Michael J. , Roy Alain 
Published: March 2003

Ronquist et al. (1999) recoded Rasnitsyn’s (1988) analysis to effect an explicit numerical cladistic analysis of his data. Here we examine their analysis and reveal that much of the resolution obtained for apocritan relationships is dependant on reductional wing characters. The wing characters in their matrix are replaced with a revised set of wing characters and reanalysed using strict parsimony. For apocritan taxa the resulting strict consensus tree is considerably less resolved, but perhaps preferable as a more conservative starting point in the continuing investigation of higher level hymenopteran relationships.
Phylogeny of the holometabolous insect orders: molecular evidence
Authors: Whiting Michael F. 
Published: March 2003

Phylogenetic relationships among the holometabolous insect orders were reconstructed using 18S ribosomal DNA data drawn from a sample of 182 taxa representing all holometabolous insect orders and multiple outgroups. Parsimony analysis supports the monophyly of all holometabolous insect orders except for Coleoptera and Mecoptera. Mecoptera is paraphyletic with respect to Siphonaptera, which is nested within Mecoptera. Coleoptera is scattered as a paraphyletic assemblage across the tree topology. These data support a monophyletic Halteria (Strepsiptera + Diptera), Amphiesmenoptera (Trichoptera + Lepidoptera), Neuropterida (Neuroptera + (Megaloptera + Raphidioptera)), but Antliophora (Halteria + Mecoptera + Siphonaptera) and Mecopterida (Antliophora + Amphiesmenoptera) are paraphyletic. The limitations of using 18S ribosomal DNA as the sole phylogenetic marker for reconstructing insect ordinal relationships are discussed.