bluuebunny/crossref_metadata_2025 huggingface dataset:
Adherence to Pressure Ulcer Prevention Guidelines: Implications for Nursing Home Quality
Authors: Saliba Debra , Rubenstein Lisa V. , Simon Barbara , Hickey Elaine , Ferrell Bruce , Czarnowski Elaine , Berlowitz Dan
Published: March 2003

OBJECTIVES: This study aims to assess overall nursing home (NH) implementation of pressure ulcer (PU) prevention guidelines and variation in implementation rates among a geographically diverse sample of NHs.

DESIGN: Review of NH medical records.

SETTING: A geographically diverse sample of 35 Veterans Health Administration NHs.

PARTICIPANTS: A nested random sample of 834 residents free of PU on admission.

MEASUREMENTS: Adherence to explicit quality review criteria based on the Agency for Healthcare Research and Quality Practice Guidelines for PU prevention was measured. Medical record review was used to determine overall and facility‐specific adherence rates for 15 PU guideline recommendations and for a subset of six key recommendations judged as most critical.

RESULTS: Six thousand two hundred eighty‐three instances were identified in which one of the 15 guideline recommendations was applicable to a study patient based on a specific indication or resident characteristic in the medical record. NH clinicians adhered to the appropriate recommendation in 41% of these instances. For the six key recommendations, clinicians adhered in 50% of instances. NHs varied significantly in adherence to indicated guideline recommendations, ranging from 29% to 51% overall adherence across all 15 recommendations (P < .001) and from 24% to 75% across the six key recommendations (P < .001). Adherence rates for specific indications also varied, ranging from 94% (skin inspection) to 1% (education of residents or families). Standardized assessment of PU risk was identified as one of the most important and measurable recommendations. Clinicians performed this assessment in only 61% of patients for whom it was indicated.

CONCLUSIONS: NHs' overall adherence to PU prevention guidelines is relatively low and is characterized by large variations between homes in adherence to many recommendations. The low level of adherence and high level of variation to many best‐care practices for PU prevention indicate a continued need for quality improvement, particularly for some guidelines.
Malnutrition in Institutionalized Seniors: The Iatrogenic Component
Authors: Wendland Barbara E. , Greenwood Carol E. , Weinberg Iris , Young Karen W. H.
Published: March 2003

OBJECTIVES: To provide practitioners with benchmarks for micronutrient supplementation policies for older residents of long‐term care (LTC) facilities, based upon residents' usual energy intake.

DESIGN: Retrospective secondary analysis of nutrient intake and delivery data, obtained from 21 consecutive collection days.

SETTING: A fully accredited geriatric teaching facility, affiliated with the University of Toronto's Medical School, that includes a chronic care hospital and a home for the aged, housing more than 800 senior residents.

PARTICIPANTS: Twenty‐three cognitively impaired residents who retained the ability to feed themselves.

MEASUREMENTS: Average daily micronutrient (vitamin and mineral) content of two common diet types—unrestricted diet as tolerated and lactose‐free—were evaluated based upon all foods served during a 28‐day cycle of menus, providing an estimate of total possible micronutrient intake. Energy intake needed to meet recommended intakes for each of the micronutrients was then determined and compared with actual dietary intakes.

RESULTS: Even if entirely consumed, neither diet (providing approximately 2,000 kcal/d) supplied sufficient quantities of vitamins (vitamin E, pantothenic acid) and minerals (calcium, zinc, copper and manganese) to enable residents to meet recommended intakes, making these deficiencies iatrogenic in nature. As projected intake levels fell to reflect ranges more consistently observed in LTC residents (1,000–1,500 kcal/d), the number and severity of risk nutrients increased. Similar predictions, based upon actual intake measurements, were made and confirmed.

CONCLUSIONS: The traditional approach of developing LTC menus using resources such as Canada's Food Guide or the Food Guide Pyramid of the United States results in iatrogenic malnutrition. New guidelines are needed that are targeted toward the special needs of older adults who have low food intakes. In the interim, all older LTC residents require full‐spectrum vitamin and mineral supplements.
Development of a Scale to Predict Decline in Patients with Mild Alzheimer's Disease
Authors: Santillan Concepcion E. , Fritsch Thomas , Geldmacher David S.
Published: March 2003

OBJECTIVES: To develop a scale that can assist in predicting likelihood of decline from mild dementia over 1 year in patients with Alzheimer's disease (AD).

DESIGN: Retrospective cohort study.

SETTING: University Memory and Aging Center.

PARTICIPANTS: Patients with probable or possible AD and Clinical Dementia Rating (CDR) of 1 at baseline, divided into development and validation cohorts (n = 118 each).

MEASUREMENTS: The CDR and neurological and neuropsychological assessments were given at baseline and 1 year later.

RESULTS: In the development cohort, high education, low Mini‐Mental State Examination score, poor insight, psychotic symptoms, and greater activity of daily living impairment predicted decline in CDR from 1 to 2 or 3. Receiver operating characteristics (ROC) curve analysis identified cutoff scores that maximized sensitivity and specificity for each significant predictor of decline. Based on the cutoff, raw scores were recoded to reflect risk for decline, weighted, and summed to create a final scale score. ROC curve analysis established a cutoff to indicate risk for decline on the final scale score. Sensitivity, specificity, and area under the ROC were 0.76, 0.74, and 0.83 in the development cohort and 0.77, 0.69, and 0.80 in the validation cohort, respectively. Positive and negative predictive values were 0.71 and 0.78 in the development cohort and 0.68 and 0.78 in the validation cohort, respectively.

CONCLUSIONS: Decline from mild to moderate or severe impairment represents significant clinical change, with implications for patient and caregiver quality of life and treatment options. The clinical scale developed uses data to enhance prediction about change from mild to moderate or severe stages of AD.
Genetic inactivation of Par4 results in hyperactivation of NF‐κB and impairment of JNK and p38
Authors: Garcia‐Cao Isabel , Lafuente María José , Criado Luis M , Diaz‐Meco María Teresa , Serrano Manuel , Moscat Jorge
Published: March 2003

The Par4 gene was first identified in prostate cells undergoing apoptosis after androgen withdrawal. PAR4 was subsequently shown to interact with, and inhibit, atypical protein kinase C isoforms, functioning as a negative regulator of the NF‐κB pathway. This may explain its pro‐apoptotic function in overexpression experiments. To determine the physiological role of PAR4, we have derived primary embryonic fibroblasts (EFs) from Par4−/− mice. We show here that loss of PAR4 leads to a reduction in the ability of tumour necrosis factor‐α (TNF‐α) to induce apoptosis by increased activation of NF‐κB. Consistent with recent reports demonstrating the antagonistic actions of NF‐κB and c‐Jun amino‐terminal kinase (JNK) signalling, we have found that Par4−/− cells show a reduced activation of the sustained phase of JNK and p38 stimulation by TNF‐α and interleukin 1. Higher levels of an anti‐apoptotic JNK‐inhibitor protein, X‐chromosome‐linked inhibitor of apoptosis, in Par4−/− EFs might explain the inhibition of JNK activation in these cells.
Rapid Stimulation of the PI3‐Kinase/Akt Signalling Pathway in Developing Midbrain Neurones by Oestrogen
Authors: Ivanova T. , Mendez P. , Garcia‐Segura L. M. , Beyer C.
Published: March 2003

Oestrogen promotes the differentiation of neurones in the central nervous system. In the rodent midbrain, the maturation of dopaminergic neurones appears to be under oestrogen control. This is supported by the fact that dopaminergic cells contain nuclear oestrogen receptors‐α/β (ER). Second, aromatase is transiently expressed in the developing midbrain. In previous studies, we have shown that oestrogen increases dopamine synthesis and plasticity of dopamine cells. These effects are transmitted through classical nuclear ER but require also the stimulation of nonclassical signalling pathways involving the activation of membrane receptors. This study attempted to identify nonclassical oestrogen‐dependent signalling cascades which might be stimulated downstream of membrane ERs. Using cultured mouse midbrain cells, we could demonstrate by Western blotting, that oestrogen rapidly phosphorylates Akt, a kinase which is implicated in the phosphatidylinositol 3 (PI3)‐kinase pathway. This effect was only seen in midbrain neurones but not astrocytes. Oestrogen‐induced Akt phosphorylation was time‐ and dose‐dependent, showing highest responses after 30 min and at a steroid concentration of 10−8 and 10−6 M. Immunocytochemistry for phosphorylated Akt (pAkt) demonstrated that pAkt is predominantly found in a nuclear/perinuclear position and that oestrogen exposure increased the number of pAkt‐positive cells. To investigate the mechanisms which are involved in transmitting oestrogen effects on the cellular level, cells were treated with antagonists for distinct signalling pathways. The application of the nuclear ER antagonist ICI 182 780 did not abolish the oestrogen‐induced Akt phosphorylation. In contrast, interrupting intracellular calcium signalling with BAPTA completely prevented this effect. The PI3‐kinase inhibitor LY294002 also inhibited the activation of Akt by oestrogen. Our study clearly indicates that oestrogen can rapidly stimulate the PI3‐kinase/Akt signalling cascade in differentiating midbrain neurones. This effect requires the intermediate activation of calcium‐dependent signalling pathways. In conclusion, oestrogen effects in the developing midbrain appear to be connected with the PI3‐kinase/Akt signalling mechanism.
Agonist‐Specific and Sexual Stage‐Dependent Inhibition of Gonadotropin‐Releasing Hormone‐Stimulated Gonadotropin and Growth Hormone Release by Ryanodine: Relationship to Sexual Stage‐Dependent Caffeine‐Sensitive Hormone Release
Authors: Johnson J. D. , Chang J. P.
Published: March 2003

Differential utilization of intracellular Ca2+ stores with specific functional characteristics could be a potential mechanism for coupling various stimuli to specific cellular responses. In the goldfish pituitary, both gonadotropes and somatotropes possess multiple intracellular Ca2+ stores that are differentially coupled to agonist‐evoked exocytosis. We investigated the role of ryanodine receptor/Ca2+‐release channels (RyR) in basal and gonadotropin‐releasing hormone (GnRH)‐evoked hormone secretion from cultured gonadotropes and somatotropes using radioimmunoassay for gonadotropin (GTH‐II) and growth hormone (GH). As is the case in vivo, the basal and evoked secretion of both hormones varied with seasonal reproductive status. GnRH‐stimulated hormone release was three‐fold higher in cells from sexually mature animals compared to those in a sexually regressed state. Nanomolar doses of ryanodine evoked significant GTH‐II and GH secretion, suggesting that ryanodine‐sensitive Ca2+ stores can couple to exocytosis in both cell types. In gonadotropes, 10 µM ryanodine abolished cGnRH‐II‐evoked GTH‐II release in both sexually mature and sexually regressed fish, while sGnRH signalling was mediated by ryanodine‐sensitive Ca2+ stores in cells from sexually regressed fish only. Ryanodine‐sensitive Ca2+ stores in somatotropes were only involved in cGnRH‐II‐stimulated GH release during gonadal regression. In contrast, sGnRH‐stimulated, but not cGnRH‐II‐stimulated, GH release was significantly reduced by 1 µM xestospongin C. Although hormone release stimulated by mobilizing caffeine‐sensitive Ca2+ pools was also markedly seasonal, it was largely independent of ryanodine‐sensitive Ca2+ stores. Ryanodine‐sensitive Ca2+ stores in both cell types are not active downstream of ionomycin, BayK 8644, protein kinase C or cyclic adenosine monophosphate signalling pathways, suggesting difference from a classical Ca2+‐induced Ca2+ release system. Ours study is the first to suggest that RyR2 may be involved in the seasonal plasticity of pituitary function, which may be related to cyclic changes observed in reproduction and growth.
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

Ghrelin, 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

The 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

Background 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

Infection 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

Crassulacean 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.
Ptilochronology proves unreliable in studies of nestling Pied Flycatchers
Authors: Kern Michael D. , Cowie Richard J.
Published: March 2003

Ptilochronology does not appear to be a reliable measure of the daily growth rate of contour feathers or the nutritional state of nestling Pied Flycatchers Ficedula hypoleuca. Growth bars on primary remiges, which according to ptilochronology represent a day’s increment of feather growth, are only about half as wide as the actual daily increase in the length of these feathers while they are growing. The average width of the growth bars on primaries was also uncorrelated with other commonly used measures of growth or nutritional status (increase in body mass or in the size of the wing or tarsus), although these were highly correlated with each other. In adult flycatchers, the average width of the growth bars on tertials was unrelated to the average bar width on greater coverts, although both feathers are replaced during the winter (prenuptial) moult. This suggests that the growth bars either do not reflect the nutritional status of adults during normal periods of moult or that contour feathers in different tracts vary in their sensitivity to the nutritional status of the moulting bird. To our knowledge, this is the first time that anyone has attempted to apply ptilochronology to nestlings. It is noteworthy that a method of measuring growth and nutritional state that has shown promise when applied to induced feathers of adult birds seems to be unreliable when applied to the developing plumage of nestlings, and perhaps the normal (not‐induced) replacement plumage of adults.
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

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

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

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

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

Cultured 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

For 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

The 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

The 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.
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

In 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

Effects 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

Inhibitor‐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

In 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

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.
Molecular identification of Colletotrichum gloeosporioides causing yam anthracnose in Nigeria
Authors: Abang M. M. , Winter S. , Green K. R. , Hoffmann P. , Mignouna H. D. , Wolf G. A.
Published: March 2003

Four forms of Colletotrichum representing three distinct virulence phenotypes were found associated with foliar anthracnose of yam in Nigeria: the highly virulent (= severity of disease) slow‐growing grey (SGG); the moderately virulent fast‐growing salmon (FGS); the weakly virulent fast‐growing grey (FGG); and the moderately virulent fast‐growing olive (FGO) morphotype. Isolates of the four forms were identified as C. gloeosporioides, based on morphology. The reaction of monoconidial cultures on casein hydrolysis medium (CHM), PCR‐RFLP and sequence analysis of the internal transcribed spacer region of the ribosomal DNA (ITS1‐5·8S‐ITS2) were used to establish the identity of the yam anthracnose pathogen(s). All yam isolates were distinguished from C. acutatum by the absence of protease activity on CHM. On ITS PCR and enzymatic digestion of PCR products, all FGS, FGO and SGG isolates produced RFLP patterns identical to those of C. gloeosporioides reference isolates, while FGG isolates revealed unique ITS RFLP banding patterns. Sequence analysis of the ITS1 region and of the entire ITS region revealed that SGG, FGS and FGO isolates were highly similar (98–99% nucleotide identity) and showed 97–100% identity to C. gloeosporioides. Less than 93% similarity of these fungal isolates to reference C. acutatum and C. lindemuthianum isolates was observed. The molecular study confirmed that foliar anthracnose of yam is caused by C. gloeosporioides. While a high similarity was found among most C. gloeosporioides fungi from yam, isolates of the FGG form did not cluster with any previously described Colletotrichum species, and probably represent a distinct species.
Digital Photoelasticity: Principles, Practice and Potential
Authors: Patterson Eann A.
Published: March 2003

The 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.