bluuebunny/crossref_metadata_2025_split huggingface dataset:
Risk of Hip Fracture in Disabled Community‐Living Older Adults
Authors: Walter Louise C. , Lui Li‐Yung , Eng Catherine , Covinsky Kenneth E. 
Published: March 2003

OBJECTIVES:To determine the rate of hip fracture and risk factors associated with hip fractures in disabled older persons who enroll in the Program of All‐Inclusive Care for the Elderly (PACE), a program providing comprehensive care to community‐living nursing‐home‐eligible persons.DESIGN:Prospective cohort study between January 1990 and December 1997.SETTING:The twelve PACE demonstration sites: San Francisco, California; Columbia, South Carolina; Detroit, Michigan; Denver, Colorado; East Boston, Massachusetts; El Paso, Texas; Milwaukee, Wisconsin; Oakland, California; Portland, Oregon; Rochester, New York; Sacramento, California; and the Bronx, New York.PARTICIPANTS:Five thousand one hundred eighty‐seven individuals in PACE; mean age 79, 71% female, 49% white, 47% with dementia.MEASUREMENTS:Functional status, cognitive status, demographics, and comorbid conditions were recorded on all the participants, who were tracked for occurrence of a hip fracture. The goals were to determine the rate of hip fracture and identify risk factors.RESULTS:Two hundred thirty‐eight hip fractures (4.6%) occurred during follow‐up. The rate of hip fracture was 2.2% per person‐year. Four independent predictors of hip fracture were identified using Cox proportional hazard analysis: age of 75 and older (adjusted hazard ratio (HR) = 2.0, 95% confidence interval (CI) = 1.4–2.8); white ethnicity (HR = 2.1, 95% CI = 1.6–2.8); ability to transfer independently to and from bed, chair, and toilet (HR = 3.0, 95% CI = 1.2–7.2); and five or more Short Portable Mental Status Questionnaire errors (HR = 1.6, 95% CI = 1.3–2.1). The incidence of hip fracture ranged from 0.5% per person‐year in persons with zero to one independent risk factors to 4.7% per person‐year in those with all four independent risk factors.CONCLUSIONS:The rate of hip fracture in this cohort of disabled community‐living older adults was similar to that reported in nursing home cohorts. Older age, white race, ability to transfer independently, and cognitive impairment were independent predictors of hip fracture. Persons with these risk factors should be targeted for preventive interventions, which should include strategies for making transferring safer.
Oestrogen Receptors, Receptor Variants and Oestrogen Actions in the Hypothalamic‐Pituitary Axis
Authors: Shupnik M. A. 
Published: March 2003

AbstractInformation on oestrogen action has grown exponentially in the past decade, and recent studies have begun to define the mechanism of ligand‐dependent activation and cell‐specific effects. Oestrogen‐mediated gene transcription in a specific tissue depends on several factors, the most important of which is the presence of at least one of the two nuclear oestrogen receptor (ER) isoforms, ERα and ERβ. The presence and levels of specific ER isoform variants, along with receptor coactivator, corepressor and integrator proteins, directly modulate overall nuclear ER activity. The structure of the ligand, including both physiological oestrogens and synthetic oestrogen receptor modulators, influences ER interactions with these other proteins and thus determines the biological response. Furthermore, peptide and neurotransmitter‐stimulated intracellular signalling pathways activate specific enzyme cascades and may modify the receptors and their interacting proteins, resulting in either independent or ligand‐enhanced ER‐mediated responses. Finally, several rapid effects of oestrogen probably occur at the membrane through nongenomic pathways that may or may not require the same ER proteins that are found in the nucleus. This review concentrates on the pituitary‐hypothalamic axis and the genomic effects of oestrogen, and discusses the current knowledge of each of these factors in determining oestrogen actions in the neuroendocrine system.
Sleep Restriction Alters the Hypothalamic‐Pituitary‐Adrenal Response to Stress
Authors: Meerlo P. , Koehl M. , Van Der Borght K. , Turek F. W. 
Published: March 2003

AbstractChronic sleep restriction is an increasing problem in many countries and may have many, as yet unknown, consequences for health and well being. Studies in both humans and rats suggest that sleep deprivation may activate the hypothalamic‐pituitary‐adrenal (HPA) axis, one of the main neuroendocrine stress systems. However, few attempts have been made to examine how sleep loss affects the HPA axis response to subsequent stressors. Furthermore, most studies applied short‐lasting total sleep deprivation and not restriction of sleep over a longer period of time, as often occurs in human society. Using the rat as our model species, we investigated: (i) the HPA axis activity during and after sleep deprivation and (ii) the effect of sleep loss on the subsequent HPA response to a novel stressor. In one experiment, rats were subjected to 48 h of sleep deprivation by placing them in slowly rotating wheels. Control rats were placed in nonrotating wheels. In a second experiment, rats were subjected to an 8‐day sleep restriction protocol allowing 4 h of sleep each day. To test the effects of sleep loss on subsequent stress reactivity, rats were subjected to a 30‐min restraint stress. Blood samples were taken at several time points and analysed for adrenocorticotropic hormone (ACTH) and corticosterone. The results show that ACTH and corticosterone concentrations were elevated during sleep deprivation but returned to baseline within 4 h of recovery. After 1 day of sleep restriction, the ACTH and corticosterone response to restraint stress did not differ between control and sleep deprived rats. However, after 48 h of total sleep deprivation and after 8 days of restricted sleep, the ACTH response to restraint was significantly reduced whereas the corticosterone response was unaffected. These results show that sleep loss not only is a mild activator of the HPA axis itself, but also affects the subsequent response to stress. Alterations in HPA axis regulation may gradually appear under conditions of long total sleep deprivation but also after repeated sleep curtailment.
Changes in total leaf nitrogen and partitioning of leaf nitrogen drive photosynthetic acclimation to light in fully developed walnut leaves
Authors: Frak E. , Le Roux X. , Millard P. , Dreyer E. , Jaouen G. , Saint‐Joanis B. , Wendler R. 
Published: March 2003

AbstractComprehensive studies on the processes involved in photosynthetic acclimation after a sudden change in light regime are scarce, particularly for trees. We tested (i) the ability of photosynthetic acclimation in the foliage of walnut trees growing outdoors after low‐to‐high and high‐to‐low light transfers made early or late in the vegetation cycle, and (ii) the relative importance of changes in total leaf nitrogen versus changes in the partitioning of leaf nitrogen between the different photosynthetic functions during a 2 month period after transfer. Changes in maximum carboxylation rate, light‐saturated electron transport rate, respiration rate, total leaf nitrogen, ribulose 1·5‐bisphosphate carboxylase/oxygenase (Rubisco) and total chlorophylls were surveyed before and after the change in light regime. Respiration rate acclimated fully within 1 week of transfer, and full acclimation was observed 1 month after transfer for the amount of Rubisco. In contrast, total nitrogen and photosynthetic capacity acclimated only partially during the 2 month period. Changes in photosynthetic capacity were driven by changes in both total leaf nitrogen and leaf nitrogen partitioning. The extent of acclimation also depended strongly on leaf age at the time of the change in light regime.
Effect of alterations in cuticular wax biosynthesis on the physicochemical properties and topography of maize leaf surfaces
Authors: Beattie G. A. , Marcell L. M. 
Published: March 2003

AbstractThe leaf surface properties of 11 cuticular wax mutants of maize were characterized, and this information was used to identify the quantitative relations among distinct leaf surface traits. Compared with the wild‐type maize, these mutants were reduced 3–24% in their leaf surface hydrophobicity, 20–88% in the mass of cuticular waxes on their leaves, and 52–94% in the percentage of planar leaf surface area covered with epicuticular crystalline waxes. They also differed in the presence and abundance of the epicuticular crystalline waxes in each of seven structural classes. With the exception of one mutant, the mass of cuticular waxes produced by these mutants was positively correlated with the number of epicuticular crystalline waxes per unit area on their leaves. Furthermore, an increase of 0·4 mg of cuticular wax per gram of leaf (dry weight) was associated with a 1% increase in leaf surface area covered by epicuticular crystalline waxes, and this 1% increase was associated with a 2° increase in the contact angle of a water droplet on the leaf surface. Linear differences in the leaf surface hydrophobicity were associated with exponential differences in the mass of the cuticular waxes produced. Quantitative knowledge of these leaf surface properties is highly relevant to the interactions of leaves with environmental factors such as microbes, insects, agricultural chemicals, and pollutants.
Prostaglandin D2, its metabolite 15‐d‐PGJ2, and peroxisome proliferator activated receptor‐γ agonists induce apoptosis in transformed, but not normal, human T lineage cells
Authors: Harris Sarah G. , Phipps Richard P. 
Published: March 2003

SummaryProstaglandin D2 (PGD2) is abundantly produced by mast cells, platelets, and alveolar macrophages and has been proposed as a key immunoregulatory lipid mediator. 15‐Deoxy‐Δ12,14‐PGJ2 (15‐d‐PGJ2), a key PGD2 metabolite, is under intense study as a potential anti‐inflammatory mediator. Little is known about PGD2 or the role of 15‐d‐PGJ2, if any, in regulating the activities of human T lineage cells. In this report we demonstrate that both PGD2 and 15‐d‐PGJ2 have potent antiproliferative effects, and in fact kill human T lymphocyte lines derived from malignant cells by an apoptotic mechanism. Interestingly, normal human T cells were not similarly affected. Although the T lymphocyte lines express mRNA for the PGD2 receptor (DP‐R), a potent DP receptor agonist, BW245C, did not inhibit the proliferation or viability of the cells, suggesting an alternative mechanism of action. PGD2 and 15‐d‐PGJ2 can bind to the peroxisome proliferator activated receptor‐γ (PPAR‐γ) which is implicated in lipid metabolism and apoptosis. Exposure to synthetic PPAR‐γ ligands (e.g. ciglitazone, troglitazone) mimicked the inhibitory responses of PGD2 and 15‐d‐PGJ2, and induced apoptosis in the transformed T cells consistent with a PPAR‐γ‐dependent mechanism. These observations suggest that PPAR‐γ ligands (which may include PGD2) provide strong apoptotic signals to transformed, but not normal T lymphocytes. Thus, the efficacy of utilizing PPAR‐γ and its ligands as therapeutics for human T cell cancers needs to be further evaluated.
CXCR4 expression on monocytes is up‐regulated by dexamethasone and is modulated by autologous CD3+ T cells
Authors: Caulfield Jason , Fernandez Maria , Snetkov Vladimir , Lee Tak , Hawrylowicz Catherine 
Published: March 2003

SummaryChemokines and their receptors regulate cell migration to sites of inflammation. The glucocorticoid dexamethasone has potent anti‐inflammatory effects, yet paradoxically up‐regulates expression of some cytokine receptors. We have examined the effects of dexamethasone on chemokine receptor expression. Using an RNase protection assay, we show that dexamethasone up‐regulates human peripheral blood mononuclear cell (PBMC) expression of CXCR4 mRNA. Flow cytometric analysis demonstrated that increased expression of CXCR4, but not CXCR1 and CXCR2, occurred on both monocytes and CD3+ T cells in PBMC mixed cultures. A stromal‐derived factor (SDF)‐1α‐mediated calcium influx was detected on monocytes. Basal levels of CXCR4 expression on purified monocytes were lower when compared with monocytes in mixed PBMC cultures. Co‐culture of monocytes with purified CD3+ T cells led to enhanced basal expression of CXCR4 on monocytes. The use of transwells to partition CD3+ T cells resulted in increased CXCR4 expression on monocytes, suggesting that CD3+ T‐cell derived soluble factors regulate CXCR4 expression.
Brief and repeated noise exposure produces different morphological and biochemical effects in noradrenaline and adrenaline cells of adrenal medulla
Authors: Gesi Marco , Lenzi Paola , Alessandrì Maria G. , Ferrucci Michela , Fornai Francesco , Paparelli Antonio 
Published: March 2003

AbstractExposure to stressful stimuli is known to activate the peripheral sympathetic nervous system and the adrenal gland. In this study, we evaluated the effects of single or repeated bouts of exposure to a readily measurable stressful stimulus (loud noise) on the catecholamine content and ultrastructure of the rat adrenal medulla. In particular, we measured tissue levels of dopamine, noradrenaline, adrenaline and metabolites. In parallel studies, we evaluated the fine ultrastructure of catecholamine cells, including a detailed study of catecholamine granules and a morphometric analysis of adrenaline and noradrenaline medullary cells. Animals were exposed either to a single (6 h) session of loud (100 dBA) noise, or to this noise stimulus repeated every day for 21 consecutive days. There was a marked correlation between biochemical indexes of catecholamine activity and the ultrastructural morphometry of specific catecholamine granules. Exposure to loud noise for 6 h induced a parallel increase in dopamine, noradrenaline, adrenaline and their metabolites, a polarization and an increased numerical density of noradrenaline and adrenaline granules in the cells. After repeated noise exposure, noradrenaline levels were significantly higher than in controls, and adrenaline decreased significantly. In addition, adrenaline cells also exhibited ultrastructural alterations consisting of wide homogeneous cytoplasmic areas and large, pale vesicles.
Social organization of cooperatively breeding long‐tailed tits: kinship and spatial dynamics
Authors: Hatchwell B. J. , Anderson C. , Ross D. J. , Fowlie M. K. , Blackwell P. G. 
Published: March 2003

Summary

Long‐tailed tits Aegithalos caudatus L. are cooperative breeders in which breeders that have failed in their own breeding attempt become helpers at the nest of relatives. We investigated the effects of kinship on the spatial dynamics of non‐breeding flocks of long‐tailed tits in order to determine the information available on the kinship of other members of the population from their use of home ranges.
A novel method of home range analysis was devised based on ‘convex hull peeling’. This method takes into account the dispersion of all fixes within a home range and permits the quantitative analysis of home range use. In addition, the method allows the extent of overlap between adjacent home ranges to be determined and the use of those areas to be investigated.
Non‐breeding flocks of long‐tailed tits were composed mainly of relatives, but also included unrelated immigrants. Flock ranges were large and there was extensive overlap between adjacent flocks.
The degree of range overlap was significantly affected by the relatedness of flocks. If two flocks contained close relatives they were more likely to overlap than two flocks containing non‐relatives. Moreover, the amount of overlap was significantly greater for two adjacent related flocks than for two adjacent unrelated flocks.
The use of overlapping areas of non‐breeding ranges of long‐tailed tit flocks was also influenced significantly by relatedness. Overlapping flocks that were unrelated to each other usually avoided areas of overlap, while related flocks did not generally show such avoidance behaviour.
Kinship has significant effects on the spatial dynamics of non‐breeding flocks of long‐tailed tits and therefore flock behaviour can provide information on the relatedness of other members of the population that might be important for helping decisions in this cooperatively breeding species.
Costs and benefits of prey specialization in a generalist insect predator
Authors: Rana J. S. , Dixon A. F. G. , Jarošík V. 
Published: March 2003

Summary

There are very few studies on prey specialization in predatory insects. Of the prey that the larvae of the generalist ladybird beetle Adalia bipunctata regularly feed on in the field, some are more suitable as food than others. A laboratory experiment was undertaken to determine whether it is possible to select for improved performance of this insect predator on a ‘poor quality’ prey, and the cost, if any, of such specialization.
The ladybird performed better when reared on the pea aphid Acyrthosiphon pisum than on the black bean aphid Aphis fabae. Over the course of six generations of selection there was a significant increase in performance on both species of aphid, especially the black bean aphid.
Ladybirds previously selected for five generations for better performance on the black bean aphid performed significantly worse when reared on pea aphid compared with those reared continuously for six generations on pea aphids, and vice versa. That is, specialization on one species of aphid resulted in a poorer performance on another.
If, as reported here, the specialization on one kind of prey generally entails a trade‐off in performance on another, then the interactions between insect predators and their prey are more homologous to those of herbivorous insects and plants than previously thought. The significance of this for prey specialization in ladybird beetles is discussed.
The life‐history basis of latitudinal diversity gradients: how do species traits vary from the poles to the equator?
Authors: Cardillo Marcel 
Published: March 2003

Summary1.Latitudinal variation among species in life‐history traits is often suggested to contribute to high tropical species richness. However, traditional methods of analysing such variation rarely control for phylogeny and latitudinal range overlap between species, potentially giving misleading results.2.Using a method of pairwise independent contrasts which overcomes these problems, I tested for latitudinal variation among bird species in a number of traits which have been linked, theoretically or empirically, with both latitude and species richness.3.This method indicates strong support for Rapoport’s Rule and decreasing clutch size towards the equator in both hemispheres, but only partial support for decreasing body size and ecological generalism towards the equator.4.Indirect measures of sexual selection (sexual dichromatism and size dimorphism) show no variation with latitude; an apparent increase in dichromatism towards the equator is shown to be an artefact of phylogeny.5.Many of the associations between life history and latitude were not detected by traditional cross‐species analyses, highlighting the importance of incorporating phylogeny and overlap in studies of geographical life‐history variation. Establishing associations between life‐history traits and latitude does not prove, but is a necessary prerequisite for, a link between these traits and latitudinal diversity gradients.
Shared predators and indirect trophic interactions: lemming cycles and arctic‐nesting geese
Authors: Bêty Joël , Gauthier Gilles , Korpimäki Erkki , Giroux Jean‐François 
Published: March 2003

Summary

We investigated the hypothesis that cyclic lemming populations indirectly affect arctic‐nesting greater snow geese (Anser caerulescens atlanticus L.) through the behavioural and numerical responses of shared predators.
The study took place on Bylot Island in the Canadian High Arctic during two lemming cycles. We recorded changes in foraging behaviour and activity rate of arctic foxes, parasitic jaegers, glaucous gulls and common ravens in a goose colony during one lemming cycle and we monitored denning activity of foxes for 7 years. We also evaluated the total response of predators (i.e. number of eggs depredated).
Arctic foxes were more successful in attacking lemmings than goose nests because predators were constrained by goose nest defence. Predators increased their foraging effort on goose eggs following a lemming decline.
Activity rates in the goose colony varied 3·5‐fold in arctic foxes and 4·8‐fold in parasitic jaegers, and were highest 2 and 3 years after the lemming peak, respectively. The breeding output of arctic foxes appeared to be driven primarily by lemming numbers.
Predators consumed 19–88% of the annual goose nesting production and egg predation intensity varied 2·7‐fold, being lowest during peak lemming years. Arctic foxes and parasitic jaegers were the key predators generating marked annual variation in egg predation.
Our study provides strong support for short‐term, positive indirect effects and long‐term, negative indirect effects of lemming populations on arctic‐nesting geese. The outcome between these opposing indirect effects is probably an apparent competition between rodents and many terrestrial arctic‐nesting birds.
Optical far‐field microscopy of single molecules with 3.4 nm lateral resolution
Authors: Bloeß A. , Durand Y. , Matsushita M. , Van Dermeer H. , Brakenhoff G. J. , Schmidt J. 
Published: March 2003

SummaryOptical far‐field imaging of single molecules in a frozen solution at 1.2 K with a lateral resolution of 3.4 nm is reported. The mechanical stability of the fluorescence microscope, especially of the low‐temperature insert, allows for the localization of fluorescing molecules with a reproducibility of better than 5 nm within observation times up to 10 min. For observation times of 9 h the reproducibility of the lateral position is limited to about 20 nm due to mechanical drift. Lateral position and orientation of 314 single molecules, present within the confocal detection volume of ~10 µm3, are obtained. The possibility to correct for mechanical drift by monitoring the position of a spatial reference in the sample is demonstrated.
3D in‐vivo X‐ray microtomography of living snails
Authors: Postnov A. , De clerck N. , Sasov A. , Van dyck D. 
Published: March 2003

SummaryIn this paper we report the first in‐vivo scanning of living snails by desktop X‐ray microtomograph with a resolution up to 10 m. Consecutive cross‐sections were acquired without destroying the specimen. Subsequently, 3D images were reconstructed. The results clearly demonstrate the possibilities of in‐vivo scanning. Processes of growth and regeneration of living snails were visualized over a period of time.