bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential signalling pathways underlying corticotrophin‐releasing hormone‐mediated neuroprotection from excitotoxicity in rat hippocampus
Authors: Elliott‐Hunt Caroline R. , Kazlauskaite Jurate , Wilde Geraint J. C. , Grammatopoulos Dimitris K. , Hillhouse Edward W. 
Published: March 2003

AbstractIn several neurological disorders including cerebral ischaemia, glutamate has been implicated as a neurotoxic agent in the mechanisms leading to neuronal cell death. The role of corticotrophin‐releasing hormone (CRH), the 41‐amino acid peptide, which activates the HPA axis in response to stressful stimuli, remains controversial. In this study, we report that CRH in low physiological concentrations (2 pm), prevented glutamate‐induced neurotoxicity via receptor‐mediated mechanisms when administered to organotypic hippocampal cultures both during and after the glutamate‐induced insult. Detailed investigations on the mechanisms mediating this neuroprotective effect showed that activation of the adenylate cyclase pathway and induction of MAP kinase phosphorylation mediate the CRH action. In addition we showed that CRH can inhibit the phosphorylation of JNK/SAPK by glutamate. Most importantly, we showed that CRH can afford neuroprotection against neurotoxicity up to 12 h following the insult, suggesting that CRH is acting at a late stage in the neuronal death cycle, and this might be important in the development of novel neuroprotective agents in order to improve neuronal survival following the insult.
Ca2+‐independent vesicular catecholamine release in PC12 cells by nanomolar concentrations of Pb2+
Authors: Westerink Remco H. S. , Vijverberg Henk P. M. 
Published: March 2003

AbstractEffects of Pb2+ on vesicular catecholamine release in intact and ionomycin‐permeabilized PC12 cells were investigated using carbon fibre microelectrode amperometry. Changes in intracellular Pb2+ and Ca2+ were measured from indo‐1 fluorescence by confocal laser scanning microscopy. Depolarization of intact cells and superfusion of permeabilized cells with saline containing ≥ 100 µm Ca2+ rapidly evokes quantal catecholamine release. Superfusion with up to 10 µm Pb2+‐containing saline evokes release of similar catecholamine quanta after a concentration‐dependent delay. Thresholds to induce exocytosis within 30 min of exposure are between 1 and 10 µm Pb2+ in intact cells and between 10 and 30 nm Pb2+ in permeabilized cells. Additional inhibition of exocytosis occurs in permeabilized cells exposed to 10 µm Pb2+. Using membrane‐impermeable and ‐permeable chelators it is demonstrated that intracellular Ca2+ is not required for Pb2+‐induced exocytosis. In indo‐	1‐loaded cells Pb2+ reduces the fluorescence intensity after a concentration‐dependent delay, whereas the fluorescence ratio, indicating intracellular Ca2+ concentration, remains unchanged. The delay to detect an increase in free intracellular Pb2+ (≥ 30 nm) is much longer than the delay to Pb2+‐induced exocytosis, indicating that cytoplasmic components buffer Pb2+ with high affinity. It is concluded that Pb2+ acts as a high‐affinity substitute for Ca2+ to trigger essential steps leading to vesicular catecholamine release, which occurs when only ∼20% of the intracellular high‐affinity binding capacity (∼2 attomol/cell) is saturated with Pb2+.
Identification of inhibitor‐of‐differentiation 2 (Id2) as a modulator of neuronal apoptosis
Authors: Gleichmann M. , Buchheim G. , El‐Bizri H. , Yokota Y. , Klockgether T. , Kügler S. , Bähr M. , Weller M. , Schulz J. B. 
Published: March 2003

AbstractInhibitor‐of‐differentiation 2 (Id2) belongs to a family of transcriptional modulators that are characterized by a helix loop helix region but lack the basic amino acid domain. During development, Id2 antagonizes differentiation mediated by the retinoblastoma protein, probably by scavenging downstream E‐box basic helix‐loop‐helix proteins. Here, using differential display RT‐PCR, we identify Id2 as an induced gene during serum and potassium deprivation‐induced apoptosis of cerebellar granule neurons. Consistent with a biological role for induced Id2 messenger RNA and protein expression in neuronal cell death, expression of Id2 antisense RNA, or targeted deletion of the Id2 gene in neurons from Id2 knock‐out mice, protect from apoptosis. Further, gene transfer‐ mediated overexpression of Id2 induces neuronal cell death both in high potassium and low potassium conditions. Thus, the present study defines a role for Id2 in the modulation of neuronal apoptosis.
Decreased expression of glutamate transporters in genetic absence epilepsy rats before seizure occurrence
Authors: Dutuit Magali , Touret Monique , Szymocha Raphaël , Nehlig Astrid , Belin Marie‐Françoise , Didier‐Bazès Marianne 
Published: March 2003

AbstractIn absence epilepsy, epileptogenic processes are suspected of involving an imbalance between GABAergic inhibition and glutamatergic excitation. Here, we describe alteration of the expression of glutamate transporters in rats with genetic absence (the Genetic Absence Epilepsy Rats from Strasbourg: GAERS). In these rats, epileptic discharges, recorded in the thalamo‐cortical network, appear around 40 days after birth. In adult rats no alteration of the protein expression of the glutamate transporters was observed. In 30‐day‐old GAERS protein levels (quantified by western blot) were lower in the cortex by 21% and 35% for the glial transporters GLT1 and GLAST, respectively, and by 32% for the neuronal transporter EAAC1 in the thalamus compared to control rats. In addition, the expression and activity of GLAST were decreased by 50% in newborn GAERS cortical astrocytes grown in primary culture. The lack of modification of the protein levels of glutamatergic transporters in adult epileptic GAERS, in spite of mRNA variations (quantified by RT‐PCR), suggests that they are not involved in the pathogeny of spike‐and‐wave discharges. In contrast, the alteration of glutamate transporter expression, observed before the establishment of epileptic discharges, could reflect an abnormal maturation of the glutamatergic neurone–glia circuitry.
Lack of evidence for programmed root senescence in common bean (Phaseolus vulgaris) grown at different levels of phosphorus supply
Authors: Fisher Maria C. T. , Eissenstat David M. , Lynch Jonathan P. 
Published: March 2003

Summary

The influence of phosphorus (P) availability on root lifespan in common bean (Phaseolus vulgaris cv. Carioca) is reported here, as well as patterns of root survivorship in relation to vegetative and reproductive development.
Plants were grown in a glasshouse in a sand‐culture system with varying P availability, and in a high‐P field soil with greater biotic activity. Root dynamics were assessed using a minirhizotron system.
Phosphorus limitation, which reduced plant growth by 90%, did not diminish root survivorship. At nonlimiting and limiting P, root survivorship was not synchronized closely with shoot development and senescence; a substantial portion of the roots were present and seemingly alive even beyond reproductive maturity. In field‐grown beans and in beans under severe P limitation in sand culture, survivorship fell approx. 50%, but only after pod fill was nearly complete.
Common bean does not exhibit programmed root senescence during and immediately following pod fill. Roots died after the shoot had undergone other senescence processes, such as leaf drop and pod dry‐down. Under field conditions, soil organisms are likely to modulate the effects of phosphorus deficiency and pod fill on root death.
Digital Photoelasticity: Principles, Practice and Potential
Authors: Patterson Eann A. 
Published: March 2003

AbstractThe enormously enhanced power of photoelasticity resulting from adoption of digital technologies is highlighted and discussed. An overview of the principal techniques of digital fringe processing is provided within a single theoretical framework. The practical application of the new technologies using both conventional instruments and novel optical devices is discussed. Experiments involving more 1 × 106 quantitative fringe order measurements are possible and practical on a routine basis using the current technology. Products based on this research are beginning to appear on the market so that many new application areas are opening up for photoelasticity, such as dynamic events, real‐time fatigue crack analysis, monitoring polarisation changes at a microscopic level in materials; detailed validation of numerical simulations, particularly of complex geometry and loading; and in‐service monitoring using reflection photoelasticity of damage in both homogeneous and heterogeneous materials, such as composites.
Assessment of the Structural Response of Masonry Cross Vaults
Authors: Theodossopoulos D. , Sinha B. P. , Usmani A. S. , Macdonald A. J. 
Published: March 2003

AbstractCross vaults have been used extensively in the roofing of medieval buildings. Knowledge of the behaviour of cross vaults under load is fundamental for the planning of structurally compatible and economic conservation programmes. A method is presented here to assess their safety under various loading conditions. A 1/4‐scale model was built in wood, representing an aisle vault of the partially collapsed Abbey Church of Holyrood in Edinburgh. The structure was loaded with dead weight and deformations and strains were recorded. Subsequently, the abutments were allowed to move progressively to cause the collapse of the vault. Finite element modelling was employed to interpret the experimental pattern, confirming the collapse of the vault was due to the development of hinges along the transverse vertex and the front abutments and membrane cracks at the back groins.
Chemokine and cytokine expression in murine intestinal epithelium following Nippostrongylus brasiliensis infection
Authors: Rosbottom Anne , Knight Pamela A. , McLachlan Gerry , Thornton Elizabeth M. , Wright Steven W. , Miller Hugh R. P. , Scudamore Cheryl L. 
Published: March 2003

SummaryInfection of mice with the nematode parasite Nippostrongylus brasiliensis results in a well characterized intestinal mastocytosis with intraepithelial migration of mucosal mast cells (MMC). The molecules mediating this response are unknown. We examined expression of several putative mast cell chemoattractants in intestinal epithelium following N. brasiliensis infection. Expression of the chemokines monocyte chemoattractant protein‐1 (MCP‐1), macrophage inflammatory protein‐1α(MIP‐1α), RANTES (regulated on activation normal T‐cell expressed and secreted), fractalkine, and thymocyte expressed chemokine (TECK); and the cytokines stem cell factor (SCF) and transforming growth factor β1 (TGFβ1), was constitutive and no alteration was detected following infection. MCP‐1 expression was also constitutive but at much lower levels and increased expression was detected on days 7 and 14 postinfection. Expression of MCP‐1 in whole jejunum was at much higher levels than in epithelium. Constitutive expression of MCP‐1, MIP‐1α and TGFβ1 was also detected in cultured bone marrow‐derived homologues of MMC. In an intestinal epithelial cell line (CMT‐93), there was constitutive expression of SCF, TGFα1, fractalkine and MCP‐1. The results show that, in vivo, epithelium is a potentially important source of mast cell chemoattractants.
Dynamic torque and apical forces of ProFile .04 rotary instruments during preparation of curved canals
Authors: Peters O. A. , Barbakow F. 
Published: March 2003

AbstractAim To analyse torque and force generated whilst shaping curved canals using rotary instruments.Methodology A specially designed computer‐controlled testing platform was used to record events during the shaping of straight and curved canals in plastic blocks and in extracted human teeth using ProFile .04 instruments. Size 40 apical stops were prepared using crown‐down, apical preparation and step‐back procedures. Maximum torque, apically directed force and the numbers of revolutions were recorded at a resolution of 100 samples s−1. Load causing separation as required by the ISO 3630–1 test and cyclic fatigue was also recorded. Mean maximum scores were calculated and statistically tested using one‐ and two‐way analyses of variance.Results Highest and lowest torque scores were recorded, respectively, in straight canals in plastic blocks at 25 Nmm and in natural canals at 14 Nmm. Significant differences were recorded for canal type and preparation phase (P < 0.0001). Loads causing separation varied from 3.7 to 32.3 Nmm. Apically directed forces ranged from 1 to 7.5 N. Again, there were significant differences depending on canal type and preparation phase (P < 0.0001). The number of revolutions during preparation ranged from 18 to 41. Size 15, 30 and 45 ProFile .04 instruments separated after 581, 430 and 402 revolutions, respectively, in a standard cyclic fatigue test.Conclusions The new torque‐testing platform details physical parameters during preparation of curved canals. To improve predictability, instrumentation sequences must be tested for excessively high torsional moments or forces. This study indicated that up to 10 curved canals could be safely prepared with a sequence of ProFile. 04 rotary instruments without separation due to cyclic fatigue. Efforts should continue to correlate root canal anatomy with torque and force generated during rotary root canal preparation.
Plagioclase replacement textures in partially eclogitised gabbros from the Sanddal mafic‐ultramafic complex, Greenland Caledonides
Authors: Lang H. M. , Gilotti J. A. 
Published: March 2003

AbstractThe Sanddal mafic‐ultramafic complex (SMUK) is a cluster of variably eclogitised mafic and ultramafic bodies that comprise the westernmost known eclogite facies locality in the North‐East Greenland eclogite province (NEGEP). Although there are no true eclogites in the SMUK, we interpret three distinct textural types of plagioclase replacement to record sequential stages in adjustment of SMUK olivine gabbro‐norites to eclogite facies conditions. The earliest stage, in which plagioclase was replaced by omphacite/spinel symplectite before nucleation of garnet (Type 1A & 1B) has not previously been described. Documentation of this texture provides clear evidence that, at least in some cases, garnet nucleation is delayed relative to nucleation of omphacite and is a rate‐limiting step for eclogitisation. Type 1C domains were produced by scattered nucleation of garnet in the same sample. In Type 2 domains, plagioclase was replaced by a layered corona with an outer layer of garnet, an inner layer of omphacite and an interior of inclusion‐rich plagioclase. In Type 3 domains, the omphacite layer was overgrown by the garnet rim, and omphacite is preserved only as inclusions in garnet. In more coarse grained leucogabbros, recrystallization was more complete, plagioclase replacement textures were less localised, and could not be divided into distinct stages. Plagioclase replacement in SMUK samples was not isochemical, and required diffusion of at least Mg and Fe from replacement of mafic phases in the surroundings. Strong compositional gradients in garnet reflect disequilibrium and were controlled by the different diffusion rates of Mg/Fe and Ca, different local chemical environments, and progress of the plagioclase breakdown reaction. The presence of small amounts of hydrous minerals (amphibole, phlogopite and clinozoisite) in local equilibrium in plagioclase domains of most SMUK samples indicates that a small amount of H2O was present during high pressure metamorphism.
Stepwise accumulation and ascent of magmas
Authors: Bons P. D. , Dougherty‐Page J. , Elburg M. A. 
Published: March 2003

AbstractOne of the currently popular theories on magma ascent is that it mainly occurs by propagating hydrofractures (dykes) and that magma viscosity is the primary rate‐controlling factor. This theory is based on mathematical models for single hydrofractures under idealised conditions. We simulated magma ascent with air ascending through gelatine and observed that the air ascended in batches, following paths made by their predecessors. Multiple batches accumulate at obstacles along the path. Although magma viscosity may control ascent rate during movement, obstacles ultimately control the size and average ascent velocity of ascending batches. We propose that step‐wise movement of magma batches is the mechanism of primary accumulation and ascent from the partially molten source rock of a magma to its first emplacement site and therefore the main ascent mechanism for granitic magmas. ‘Classical’ dyking is the mechanism for secondary ascent from a magma chamber.
Substance P: a pioneer amongst neuropeptides
Authors: Hökfelt T. , Pernow B. , Wahren J. 
Published: March 2003

Abstract.   Hökfelt T, Pernow B, Wahren J (Karolinska Institutet, Stockholm, Sweden). Substance P: a pioneer amongst neuropeptides. J Intern Med 2001; 249: 27–40.A brief overview of recent developments in the substance P field is provided, in addition to a historical introduction. It is emphasized that there are multiple tachykinins and tachykinin receptors and that there are examples of coexistence of several tachykinin peptides and of several tachykinin receptors in single cells, and there is evidence for tachykininergic cotransmission. The distribution and functional significance of tachykinins in the gastrointestinal tract and in sensory neurones, and interactions with other peptides and transmitters, are reviewed. The recent production of knock‐out mice for either substance P or the NK1 receptor is discussed, as well as the exciting concept of substance P receptor internalization. Finally, the development of specific substance P antagonists is summarized, and possible clinical implications discussed, and, in particular, a recent study which reports that a substance P antagonist shows clinical efficacy in depression.
Sebaceous adenitis in the Akita: clinical observations, histopathology and heredity
Authors: Reichler Iris M. , Hauser Beat , Schiller Irene , Dunstan Robert W. , Credille Kelly M. , Binder Heinrich , Glaus Toni , Arnold Susi 
Published: March 2003

AbstractNinety‐seven pure‐bred Akitas were examined clinically and histologically for sebaceous adenitis. The diagnosis was established histologically in 23 Akitas by demonstrating an inflammatory reaction targeted against the sebaceous glands or a reduction in the number of glands. The clinical course of sebaceous adenitis in the Akita was similar to that seen in other breeds. The first skin lesions occurred mainly on the dorsal midline and ears. Compared with the Poodle, the age at first onset of the disease was more variable and the hair loss affected mainly the undercoat. The progression of sebaceous gland destruction varied between dogs and was not seen in all cases. Because bud‐like sebaceous gland proliferation could be identified, it seems that regeneration of the sebaceous glands may occur. An autosomal recessive inheritance appears to be possible. Apart from a genetic background, immune‐mediated factors possibly influence the onset and course of sebaceous adenitis.
Characterization and translational regulation of the arginine decarboxylase gene in carnation (Dianthus caryophyllus L.)
Authors: Chang Kwang Suk , Lee Sun Hi , Hwang Seong Bin , Park Ky Young 
Published: March 2003

SummaryArginine decarboxylase (ADC; EC 4.1.1.9) is a key enzyme in polyamine biosynthesis in plants. We characterized a carnation genomic clone, gDcADC8, in which the deduced polypeptide of ADC was 725 amino acids with a molecular mass of 77.7 kDa. The unusually long 5′‐UTR that contained a short upstream open reading frame (uORF) of seven amino acids (MQKSLHI) was predicted to form an extensive secondary structure (free energy of approximately −117 kcal mol−1) using the Zuker m‐fold algorithm. The result that an ADC antibody detected two bands of 45 and 33 kDa in a petal extract suggested the full length of the 78 kDa polypeptide precursor converted into two polypeptides in the processing reaction. To investigate the role of the transcript leader in translation, in vitro transcription/translation reactions with various constructs of deletion and mutation were performed using wheat germ extract. The ADC transcript leader affected positively downstream translation in both wheatgerm extract and primary transformant overexpressing ADC gene. It was demonstrated that heptapeptide (8.6 kDa) encoded by the ADC uORF was synthesized in vitro. Both uORF peptide, and the synthetic heptapeptide MQKSLHI of the uORF, repressed the translation of downstream ORF. Mutation of the uORF ATG codon alleviated the inhibitory effect. ORF translation was not affected by either a frame‐shift mutation in uORF or a random peptide. To our knowledge, this is the first report to provide evidence that a uORF may inhibit the translation of a downstream ORF, not only in cis but also in trans, and that the leader sequence of the ADC gene is important for efficient translation.
Pistillody, homeotic transformation of stamens into pistil‐like structures, caused by nuclear–cytoplasm interaction in wheat
Authors: Murai Koji , Takumi Shigeo , Koga Hironori , Ogihara Yasunari 
Published: March 2003

SummaryHomeotic transformation of stamens into pistil‐like structures (pistillody) has been observed in a cytoplasmic substitution (alloplasmic) line of wheat (Triticum aestivum L.) cv. Norin 26, which has the cytoplasm of a wild relative species, Aegilops crassa L. On the other hand, an alloplasmic line of wheat cv. Chinese Spring (CS) with Ae. crassa cytoplasm has normal flowers. This is due to the presence in the CS nucleus of a fertility‐restoring gene, Rfd1. Deletion mapping analysis revealed that Rfd1 is located on the middle part of the long arm of chromosome 7B. To investigate the function of the Rfd1 gene by a loss‐of‐function strategy, we produced alloplasmic lines of CS ditelosomic 7BS [(cr)‐CSdt7BS] and CS monotelodisomic 7BS [(cr)‐CSmd7BS] with the Ae. crassa cytoplasm, and characterized their phenotypes. The line (cr)‐CSdt7BS without Rfd1 exhibited pistillody in all florets, and also female sterility. Scanning electron microscopy of the young spikes revealed that the pistillody was induced at an early stage of stamen development. The pistillate stamens often developed incomplete ovule‐like structures with integuments instead of tapetum and pollen grains. It is possible that MADS box genes are associated with the induction of pistillody, because the expression of wheat APETALA3 homologue (WAP3) was reduced in the young spikes of (cr)‐CSdt7BS. In addition, a histological study indicated that the female sterility in (cr)‐CSdt7BS is due to the abnormality of the ovule, which fails to form an inner epidermis and integuments in the chalaza region. The line (cr)‐CSmd7BS, hemizygous for Rfd1, showed partial pistillody (51%) and restored female fertility up to 72%. These results suggest that the induction of both pistillody and ovule deficiency caused by the Ae. crassa cytoplasm is inhibited by the Rfd1 gene in a dose‐dependent manner.