bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulational Effect of Ghrelin on Growth Hormone Secretion from Perifused Rat Anterior Pituitary Cells
Authors: Yamazaki M. , Nakamura K. , Kobayashi H. , Matsubara M. , Hayashi Y. , Kangawa K. , Sakai T. 
Published: March 2003

AbstractGhrelin, a novel growth hormone (GH)‐releasing peptide, was recently isolated from the rat stomach as an endogenous ligand to growth hormone secretagogue receptor (GHS‐R). Ghrelin specifically stimulates the release of GH from the rat anterior pituitary gland, but the regulational effect of ghrelin on GH secretion has not yet been clarified. We used a perifusion system to examine the single effect and combined effects of ghrelin with growth hormone‐releasing hormone (GHRH) and somatostatin on GH secretion from rat anterior pituitary cells. The increase in GH concentration due to ghrelin stimulation showed a transitory peak that was almost the same as that previously reported for GHS, but apparently distinct from that of GHRH. Ghrelin (10−10 M to 10−8 M) stimulated GH secretion from the rat anterior pituitary cells in a dose‐dependent manner. Serial ghrelin stimulation of the dispersed cells at 1‐h intervals decreased the GH response, but the response recovered with stimulation at 3‐h intervals, indicating that ghrelin strongly desensitized cells. Costimulation with ghrelin and GHRH elicited neither a synergistic nor an additive GH response from the rat pituitary cells. Furthermore, pretreatment to anterior pituitary cells with somatostatin strongly abolished ghrelin‐ and/or GHRH‐stimulated GH secretion. In this study, we demonstrated that ghrelin caused weaker GH secretion than that caused by GHRH, and we also showed that costimulation with GHRH had no additive or synergistic effect on GH secretion, suggesting that ghrelin indirectly affects coordinated GH release from pituitary gland, as found in vivo.
Functional Consequences of Morphological Neuroglial Changes in the Magnocellular Nuclei of the Hypothalamus
Authors: Oliet S. H. R. 
Published: March 2003

AbstractThe supraoptic and paraventricular nuclei of the hypothalamus undergo reversible anatomical changes under conditions of intense neurohypophysial hormone secretion, such as lactation, parturition and chronic dehydration. This morphological remodelling includes a reduction in astrocytic coverage of neurones resulting in an increase in the number and extent of directly juxtaposed somatic and dendritic surfaces. There is a growing body of evidence indicating that such anatomical plasticity is of functional significance. Astrocytic‐dependent clearance of electrolytes and neurotransmitters from the extracellular space appears to be altered under conditions where glial coverage of magnocellular neurones is reduced. Glutamate, for example, has been found to accumulate in the extracellular space in the supraoptic nucleus of lactating animals and cause a modulation of synaptic efficacy. On the other hand, the range of action of substances released from astrocytes and acting on adjacent magnocellular neurones is expected to be limited during such anatomical remodelling. It thus appears that the structural plasticity of the magnocellular nuclei does affect neuroglial interactions, inducing significant changes in signal transmission and processing.
Cutaneous leishmaniasis in Sanliurfa: epidemiologic and clinical features of the last four years (1997–2000)
Authors: Gurel Mehmet Salih , Ulukanligil Mustafa , Ozbilge Hatice 
Published: March 2003

AbstractBackground Sanliurfa is located in south‐east Anatolia, the region with the largest focus of anthroponotic cutaneous leishmaniasis (CL) in Turkey. The present study was designed to determine the epidemiological and clinical patterns of cases of CL in the Sanliurfa area over a period of 4 years (1997–2000).Methods 2120 CL cases attending the Harrankapi in this study.Results There were 790 cases of CL in 1997, and 778 in 1998. The numbers declined to 277 in 1999 and to 275 in 2000. The majority of patients (70%) were less than 20 years of age, with the highest percentage (27%) occuring in the 5‐ to 9‐year age group. Acute CL and chronic CL were observed in 1926 (90.8%) and 63 (3%) patients, respectively. Leishmaniasis recidivans (LR) was found only in 131 (6.2%) patients. Lesions of CL were seen mainly on the exposed parts of the body such as the face and neck (57.5%), upper limbs (32.2%) and lower limbs (10.2%). Ninety‐three percent of the patients were residents of central Sanliurfa from the southern and eastern parts of the city, areas with poor housing and low socio‐economic conditions.Conclusion Although the incidence of CL showed a sharp decline from 1997 to 2000 in Sanliurfa, this does not mean that the disease is on its way to eradication.
Inhibition of photosynthesis by Colletotrichum lindemuthianum in bean leaves determined by chlorophyll fluorescence imaging
Authors: Meyer S. , Saccardy‐Adji K. , Rizza F. , Genty B. 
Published: March 2003

AbstractInfection of bean leaves by Colletotrichum lundemuthianum causes vein necrosis and subsequent localized wilting of the blade. The effect of infection on photosynthesis was investigated by imaging leaf chlorophyll fluorescence as a means of mapping stomatal and metabolic inhibition of photosynthesis. During infection, CO2 assimilation (An), stomatal conductance to water vapour, and photosynthetic electron transport rate (Jt) decreased, whereas dark respiration increased. An decreased more than was expected from the reduction in green leaf area, showing that photosynthesis was inhibited in apparently healthy areas. Under subsaturating irradiance, images of Jt in air showed that photosynthesis decreased gradually, with this effect shifting from green to necrotic areas. Sudden increase in CO2 concentration to 0·74% in the atmosphere around the leaf only partially reversed this inhibition, showing that both stomatal and metabolic inhibition occurred. Under limiting irradiance, decreases in Jt and in maximal Jt during high CO2 exposure as leaf damage severity increased suggested that metabolic inhibition was mediated through an inhibition of Ribulose 1·5‐bisphosphate (RuBP) regeneration. Finally, the importance of our data in terms of assessing the loss of photosynthetic yield from visible symptoms – as is currently performed in epidemiology – is discussed.
Induction of Crassulacean acid metabolism by water limitation
Authors: Cushman J. C. , Borland A. M. 
Published: March 2003

AbstractCrassulacean acid metabolism (CAM), a key adaptation of photosynthetic carbon fixation to limited water availability, is characterized by nocturnal CO2 fixation and daytime CO2 re‐assimilation, which generally results in improved water‐use efficiency. However, CAM plants display a remarkable degree of photosynthetic plasticity within a continuum of diel gas exchange patterns. Genotypic, ontogenetic and environmental factors combine to govern the extent to which CAM is expressed. The ecological diversity of CAM is mirrored by plasticity in a range of biochemical and physiological attributes. In C3/CAM‐intermediate plants, limited water availability can induce or enhance the expression of CAM. CAM induction is controlled by a combination of transcriptional, post‐transcriptional and post‐translational regulatory events. Early events in CAM induction point to a requirement for calcium and calcium‐dependent protein kinase activities. Gene discovery efforts, improved transformation technologies and genetic models for CAM plants, coupled with detailed physiological investigations, will lead to new insights into the molecular genetic basis of induction processes and the circadian oscillator that governs carbon flux during CAM. Future integration of genomic, biochemical and physiological approaches in selected CAM models promise to provide a detailed view of the complex regulatory dynamics involved in CAM induction and modulation by water deficit. Such information is expected to have broad significance as the ecological and agricultural importance of CAM species increases in the face of global warming trends and the associated expansion of desertification in semi‐arid regions around the world.
The role of plant trichomes and caterpillar group size on growth and defence of the pipevine swallowtail Battus philenor
Authors: Fordyce James A. , Agrawal Anurag A. 
Published: March 2003

Summary

The California population of the pipevine swallowtail Battus philenor is a specialist on the Dutchman’s pipe Aristolochia californica, an endemic vine that is densely covered with trichomes. Populations of B. philenor outside California use other Aristolochia species that are largely glabrous. The average clutch size of the pipevine swallowtail is larger in California compared with populations elsewhere and larvae feed gregariously until late in the third instar.
In the field, caterpillars consumed more leaf material and showed preference for portions of leaves with trichomes removed. However, large groups of caterpillars were consistently observed feeding on the apical portion of the plant, where trichome density was highest. Smaller groups of caterpillars were observed feeding more often on mature leaves on the lower portions of the plant, where trichome density was lower.
Laboratory experiments showed that the walking speed of a commonly observed predator, larvae of the green lacewing Chrysopa carnea, was reduced as trichome density increased. Furthermore, lacewing search efficiency and capture rate of a model prey item were compromised by high trichome density.
In an additional field experiment, no difference was found in the percentage mortality of groups of four and 12 caterpillars. However, growth rate of the larger group was accelerated by 25% compared with smaller groups. In an experiment using a ladybird beetle larva Hippodamia convergens as the predator, no difference was observed in absolute mortality of caterpillars, suggesting that group size does not function directly as a defence against predators.
First instar caterpillars are most vulnerable to predators, thus feeding in larger groups may benefit caterpillars by accelerating growth. Feeding in large groups may also be an effective strategy for B. philenor to overcome plant trichomes and feed on portions of the plant conducive to faster development. However, feeding on areas with dense trichomes does not appear to provide larvae with a refuge from predators.
Long‐term disadvantages of selective root placement: root proliferation and shoot biomass of two perennial grass species in a 2‐year experiment
Authors: Fransen Bart , De Kroon Hans 
Published: March 2003

Summary

The long‐term benefits of root foraging in heterogeneous environments are unclear. The short duration of many previous studies may have overlooked the effects of patch depletion and root turnover, which may limit the long‐term rewards of root foraging for perennial plants.
The benefits of root foraging were investigated for Holcus lanatus and Nardus stricta over two growing seasons. Shoot biomass of each species was measured in homogeneous nutrient‐rich and nutrient‐poor treatments and in a heterogeneous treatment consisting of a nutrient‐rich and a nutrient‐poor side, at a high and a low overall level of nutrient availability at the same patch contrast. Large initial differences in nitrate concentrations in the soil solution between the soil types disappeared so that, after several months, nitrate levels were low in all soil types.
In heterogeneous treatments, Holcus was able to proliferate roots in the nutrient‐rich side compared with the nutrient‐poor side, but only at the high overall level of nutrient availability. Nardus did not selectively place roots in the nutrient‐rich side of the heterogeneous treatment at either nutrient level.
Root longevity, as determined by minirhizotron observations, revealed that roots of Holcus tended to be shorter lived than those of Nardus, and to live longer in nutrient‐poor soils.
Initially, Holcus produced more shoot biomass in the heterogeneous treatments, at both overall levels of nutrient availability, than expected from values in the homogeneous treatments, but this advantage disappeared by the end of the first growing season and, after 2 years, shoot biomass in the heterogeneous treatments was much less than expected. At the high overall level of nutrient availability, Holcus shoot biomass was not significantly greater than that produced in the homogeneous nutrient‐poor treatment. In contrast, shoot biomass of Nardus in the heterogeneous treatment was similar to the expected value, both after the first and second growing seasons.
For Holcus, fast root proliferation and presumably a high nutrient uptake resulted in increased shoot biomass in the short term, but this was then curtailed by rapid patch depletion and high losses due to a limited root life span. We discuss the implications for the long‐term rewards of root proliferation in perennial species of heterogeneous environments.
Influence of precipitation and species composition on phytomass of a semi‐arid African grassland
Authors: O'Connor T. G. , Haines L. M. , Snyman H. A. 
Published: March 2003

Summary The influence of botanical composition on annual phytomass production of a semi‐arid grassland in response to precipitation was tested with a 19‐year experiment. Three compositional states reflecting good, medium and poor rangeland condition, whose basal cover increased from poor through to good, were created in 1978. Multiple regression models were developed for assessing whether phytomass was influenced by precipitation, composition, phytomass of the previous year, basal cover, abundance of individual species, or diversity. Composition and precipitation accounted for 66% of the variation in phytomass, but a separate model of basal cover by precipitation was equally successful. The linear effect of rainfall on phytomass was enhanced as composition improved from poor (0.076 g m−2 mm−1) through medium (0.197 g m−2 mm−1) to good (0.277 g m−2 mm−1). Phytomass increased for low precipitation if it had been high the preceding year. Phytomass was more variable over time with deteriorating condition. Species’ complementarity ensured greater and more stable production.Setaria sphacelata,Eragrostis chloromelasandDigitaria erianthaincreased phytomass on the good or medium condition grasslands during drier years, whereasThemeda triandrahad this effect during wetter years. Precipitation‐use efficiency (PUE) was influenced mostly by composition and a linear and quadratic effect of precipitation (63% of variance). Optimum PUE of 0.308, 0.203 and 0.096 g m−2 mm−1for the good, medium and poor condition grasslands, respectively, occurred at intermediate amounts (±680 mm) of precipitation. PUE was increased if phytomass had been high the previous year. Species’ complementarity of PUE in response to precipitation was evident for all compositional states. Ten, mostly uncommon, species and their interaction with precipitation explained an extra 21–42% of the variance. Stability of production was related to PUE for medium and poor condition grassland. Uncommon species therefore ensured growth efficiency and stabilized production as condition deteriorated. Diversity had no influence on phytomass or PUE except for a small to moderate effect, respectively, for the medium condition grassland. Vegetation structure, through limiting runoff and promoting infiltration, is an important control on the amount and efficiency of plant production under variable precipitation, whilst composition further influences the amount and stability of production.
Prediction of species response to atmospheric nitrogen deposition by means of ecological measures and life history traits
Authors: Diekmann Martin , Falkengren‐Grerup Ursula 
Published: March 2003

Summary

The main objective of this study was to predict the responses of vascular plant species to atmospheric nitrogen deposition and enhanced soil nitrogen levels. The study was carried out in deciduous forests located in three regions of southern Sweden. The abundance of vascular plants, as well as soil pH and nitrogen mineralization rates, were studied in a total of 661 sample plots.
We calculated an ecological measure (Ndev value) for all species based on their observed vs. expected nitrification ratios at a given soil pH, and compared its accuracy in predicting abundance changes with results using life history traits. Data from long‐term field studies and fertilization experiments were used for validation.
Ndev values were positively correlated between neighbouring regions. Values for the southernmost region (Skåne) were also positively related to the changes in species frequency observed in large‐scale flora surveys and permanent plot studies in that area and with species changes reported from Central Europe. Values from one of two other regions were also consistent. Ndev values from Skåne (but no other region) predicted species responses in short‐term fertilization experiments.
No life history trait was as good a predictor as Ndev, although plant height, leaf anatomy, leaf nitrogen concentration and phenology showed significant correlations. Attributes related to taxonomy, life form, relative growth rate and habitat type showed no agreement with the changes in species abundance.
We predict that species with the following attribute syndrome will increase in abundance in response to enhanced nitrogen levels: those favoured by a high soil nitrification ratio relative to other species at a given soil pH, tall stature, hydro‐ to helomorph anatomy, high leaf nitrogen concentration and a late phenological development.
Stimulation of the NADPH oxidase in activated rat microglia removes nitric oxide but induces peroxynitrite production
Authors: Bal‐Price Anna , Matthias Anita , Brown Guy C. 
Published: March 2003

AbstractCultured rat microglia produced extracellular superoxide at a rate of 814 ± 52 pmol/min/million cells when stimulated with phorbol 12‐myristate 13‐acetate (PMA) as measured by extracellular cytochrome c reduction. This superoxide production resulted in a rapid rate of superoxide dismutase‐sensitive nitric oxide (NO) breakdown (155 ± 30 pmol of NO/min/million cells) when NO was added to PMA stimulated microglia. Lipopolysaccharide/interferon‐γ (LPS/IFN‐γ)‐activated microglia produce NO at the rate of 145 ± 42 pmol/min/million cells and activated astrocytes at the rate of 51 ± 9 pmol/min/million cells as estimated by NO electrode. Both types of cells maintained a steady‐state level of 0.5–0.7 µm NO, only in the presence of l‐arginine. Addition of PMA to activated microglia (but not activated astrocytes) caused the rapid and complete disappearance of all extracellular NO (but was restored in the presence of superoxide dismutase) followed by the production of peroxynitrite (as measured by urate‐sensitive oxidation of dihydrorhodamine). Co‐incubation of activated microglia with cerebellar granule neurones resulted in NO inhibition of neuronal respiration, but this was rapidly removed by PMA‐induced breakdown of the NO. Thus, microglial NADPH oxidase can regulate the bioavailability of NO and the production of peroxynitrite.
Changes in somatodendritic but not terminal dopamine regulation in aged rhesus monkeys
Authors: Gerhardt Greg A. , Cass Wayne A. , Yi Ai , Zhang Zhiming , Gash Don M. 
Published: March 2003

AbstractFor these studies, young (8–9 years), middle‐aged (14–17 years) and aged (23–28 years) rhesus monkeys were used as a model of normal aging in humans to investigate changes in dopamine (DA)‐containing neurons in senescence. Aged monkeys exhibited significant age‐related motoric declines as compared to the young animals. In vivo microdialysis studies showed that basal levels of the DA metabolites, homovanillic acid (HVA) and 3,4‐dihydroxyphenylacetic acid (DOPAC) were diminished by 44% and 79%, respectively, in␣the substantia nigra (SN) of aged monkeys. In addition,	d‐amphetamine‐evoked overflow of DA in the SN was diminished by 30% in the middle‐aged animals and 67% in the aged monkeys. Post‐mortem measures of DA and DA metabolites showed significant decreases in DA (20%), DOPAC (47%) and HVA (22%) levels in the putamen and a 25% decline in HVA tissue levels in the SN of the aged monkeys as compared to the young animals. Unbiased stereological cell counting of tyrosine hydroxylase (TH)‐immunoreactive neurons in the SN showed a small (15–20%) but significant age‐related decline in TH‐positive neurons. In addition, there was a small (15–20%) but significant decline in TH‐positive fiber density and TH‐positive cell size. In comparison to the massive loss of DA neurons responsible for the movement dysfunctions seen in Parkinson's disease, pronounced functional changes in DA release in the SN and putamen may significantly contribute to the motoric dysfunctions characterizing normal aging in rhesus monkeys.
Nicotinic acetylcholine receptors of Drosophila: three subunits encoded by genomically linked genes can co‐assemble  into the same receptor complex
Authors: Chamaon Kathrin , Smalla Karl‐Heinz , Thomas Ulrich , Gundelfinger Eckart D. 
Published: March 2003

AbstractThe second β‐like subunit (SBD) is a putative structural subunit of Drosophila melanogaster nicotinic acetylcholine receptors (nAChRs). Here we have produced specific antibodies against SBD to study, which other nAChR subunits can co‐assemble with SBD in receptor complexes of the Drosophila nervous system. Immunohistochemical studies in the adult optic lobe revealed that SBD has a distribution similar to␣that of the α‐subunit ALS in the synaptic neuropil. The subunits ALS, Dα2 and SBD can be co‐purified by α‐bungarotoxin affinity chromatography. Moreover, anti‐SBD antibodies co‐precipitate ALS and Dα2 and, vice versa, ALS and Dα2 antibodies co‐immunoprecipitate SBD protein. Two‐step immunoaffinity chromatography with immobilized antibodies against ALS and Dα2 revealed the existence of nAChR complexes that include ALS, Dα2 and SBD as integral components. Interestingly, the genes encoding these three subunits appear to be directly linked in the Drosophila genome at region 96 A of the third chromosome. In addition, SBD appears to be a component of a different receptor complex, which includes the ARD protein as an additional β‐subunit, but neither ALS nor Dα2 nor the third α‐subunit Dα3. These findings suggest a considerable complexity of the Drosophila nicotinic receptor system.
Endogenous morphine modulates acute thermonociception in mice
Authors: Guarna M. , Bianchi E. , Bartolini A. , Ghelardini C. , Galeotti N. , Bracci L. , Neri C. , Sonetti D. , Stefano G. 
Published: March 2003

AbstractThe endogenous synthesis of morphine has been clearly demonstrated throughout the phylogenesis of the nervous system of mammals and lower animals. Endogenous morphine, serving as either a neurotransmitter or neurohormone, has been demonstrated in the nervous system of both verteb‐rates and invertebrates. As one of the effects of exogenous morphine is the modulation of pain perception, we investigated the effects that the depletion of endogenous morphine had on nociceptive transmission. The immunoneutralization of endogenous morphine from brain extracellular spaces was obtained through the intracerebroventricular administration of affinity purified anti‐morphine IgG to mice, which then underwent the hot plate test. Endogenous morphine immunoneutralization decreased thermal response latency and attenuated the anti‐nociceptive effect of the mu selective agonist DAMGO in hot plate test suggesting that endogenous morphine is involved in pain modulation.