bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flower constancy in honey bee workers (Apis mellifera) depends on ecologically realistic rewards
Authors: Grüter Christoph , Moore Heather , Firmin Nicola , Helanterä Heikki , Ratnieks Francis L. W. 
Published: March 2011

SUMMARYAs first described by Aristotle, honey bee (Apis mellifera) workers show a strong tendency to visit flowers of only one type during a foraging trip. It is known that workers rapidly learn a flower colour when rewarded with artificial nectar (sucrose solution). However, some previous studies report that the degree of constancy after training is unaffected by reward quantity and quality when bees are tested in an array of artificial flowers of two easily distinguished colours, such as blue and yellow. One possible reason for this surprising result is that large reward volumes were compared. This is likely to mask the abilities of foragers to make adaptive decisions under more realistic conditions. To test this possibility, we offered untrained honey bee workers ecologically relevant rewards (0.5, 1 or 2 μl of 0.5 or 1 mol l–1 sucrose solution) on one or two consecutive yellow or blue artificial flowers and then recorded which flowers the bees subsequently landed on in an array of 40 empty flowers. The results showed that an increase in all three factors (volume, concentration and number of rewards) significantly increased constancy (proportion of visits to flowers of the trained colour) and persistence (number of flowers visited) during the foraging bout. Constancy for the least rewarding situation was 75.9% compared with 98.6% for the most rewarding situation. These results clearly show that honey bee workers do become more constant to blue or yellow with increasing nectar rewards, provided that the rewards used are ecologically realistic. As the most rewarding conditions led to nearly 100% constancy, further reward increases during training would not have been able to further increase constancy. This explains why previous studies comparing large rewards found no effect of reward on constancy.
Slipping, sliding and stability: locomotor strategies for overcoming low-friction surfaces
Authors: Clark Andrew J. , Higham Timothy E. 
Published: March 2011

SUMMARYLegged terrestrial animals must avoid falling while negotiating unexpected perturbations inherent to their structurally complex environments. Among humans, fatal and nonfatal injuries frequently result from slip-induced falls precipitated by sudden unexpected encounters with low-friction surfaces. Although studies using walking human models have identified some causes of falls and mechanisms underlying slip prevention, it is unclear whether these apply to various locomotor speeds and other species. We used high-speed video and inverse dynamics to investigate the locomotor biomechanics of helmeted guinea fowl traversing slippery surfaces at variable running speeds (1.3–3.6 m s–1). Falls were circumvented when limb contact angles exceeded 70 deg, though lower angles were tolerated at faster running speeds (&gt;3.0 m s–1). These prerequisites permitted a forward shift of the body's center of mass over the limb's base of support, which kept slip distances below 10 cm (the threshold distance for falls) and maximized the vertical ground reaction forces, thus facilitating limb retraction and the conclusion of the stance phase. These postural control strategies for slip avoidance parallel those in humans, demonstrating the applicability of these strategies across locomotor gaits and the potential for guinea fowl as an insightful model for invasive approaches to understanding limb neuromuscular control on slippery surfaces.
Burrowing and subsurface locomotion in anguilliform fish: behavioral specializations and mechanical constraints
Authors: Herrel Anthony , Choi Hon Fai , Dumont Elizabeth , De Schepper Natalie , Vanhooydonck Bieke , Aerts Peter , Adriaens Dominique 
Published: March 2011

SUMMARYFish swimming is probably one of the most studied and best understood locomotor behaviors in vertebrates. However, many fish also actively exploit sediments. Because of their elongate body shape, anguilliform fishes are not only efficient swimmers but also very maneuverable. Consequently, many species live in complexly structured environments near the bottom and many are known to burrow into the sediment. To better understand burrowing and subsurface locomotion in anguilliform fish we provide descriptive kinematic data on subsurface locomotion in a burrowing eel (Pisodonophis boro) using videofluoroscopy. We also measured the maximal forces that can be exerted by this species during head-first and tail-first burrowing, and explored the implications of head-first burrowing on mechanical stress distribution in the skull. Our data show that P. boro uses lateral undulation to penetrate and move in sandy sediments under water. The kinematics of subsurface locomotion are different from those observed during swimming and are characterized by a very high slip factor. These observations differ considerably from recently published data in terrestrial sand-swimming lizards, and suggest that the sediment behaves like a solid rather than a frictional fluid. Finally, our finite element models show that the cranial shape and structure in the head-first burrowing P. boro is mechanically more suited for head-first burrowing than that of an obligate tail-first burrowing species, Heteroconger hassi.
Significant dissociation of expression patterns of the basic helix–loop–helix transcription factors Dec1 and Dec2 in rat kidney
Authors: Wu Tao , Ni Yinhua , ZhuGe Fen , Sun Lu , Xu Bin , Kato Hisanori , Fu Zhengwei 
Published: March 2011

SUMMARY
Dec1 and Dec2 are regulators of the mammalian molecular clock that show robust circadian rhythms in the suprachiasmatic nucleus and various peripheral tissues. Although the expression of Dec1 and Dec2 is altered by multiple stimuli in different organs, their transcriptional regulatory mechanisms have not been fully elucidated for the kidney. In the present study, we describe for the first time significant dissociation of expression patterns with arrhythmic expression of Dec1 and rhythmic expression of Dec2 in rat kidney under a normal light–dark (LD) cycle. Daytime restricted feeding (RF) significantly altered the expression patterns of these two clock genes, and even induced circadian expression of Dec1 with an amplitude of 2.2 on day 3 and 4.2 on day 7. However, when a reversed feeding schedule was coupled with a reversed LD cycle, the expression of Dec1 but not Dec2 reverted to being arrhythmic. Moreover, exogenous injection of the glucocorticoid analogue dexamethasone (Dex) at certain times of the day resulted in rhythmic expression of Dec1, which was similar to that seen following RF for 7 days. In contrast, endogenous disruption of glucocorticoids by adrenalectomy abolished RF-induced rhythmic expression of Dec1 in the kidney. These observations suggest the existence of a glucocorticoid gating mechanism in the circadian expression of Dec1 in rat kidney.
Hibernating above the permafrost: effects of ambient temperature and season on expression of metabolic genes in liver and brown adipose tissue of arctic ground squirrels
Authors: Williams Cory T. , Goropashnaya Anna V. , Buck C. Loren , Fedorov Vadim B. , Kohl Franziska , Lee Trixie N. , Barnes Brian M. 
Published: March 2011

SUMMARY
Hibernating arctic ground squirrels (Urocitellus parryii), overwintering in frozen soils, maintain large gradients between ambient temperature (Ta) and body temperature (Tb) by substantially increasing metabolic rate during torpor while maintaining a subzero Tb. We used quantitative reverse-transcription PCR (qRT-PCR) to determine how the expression of 56 metabolic genes was affected by season (active in summer vs hibernating), metabolic load during torpor (imposed by differences in Ta: +2 vs –10°C) and hibernation state (torpid vs after arousal). Compared with active ground squirrels sampled in summer, liver from hibernators showed increased expression of genes associated with fatty acid catabolism (CPT1A, FABP1 and ACAT1), ketogenesis (HMGCS2) and gluconeogenesis (PCK1) and decreased expression of genes associated with fatty acid synthesis (ACACB, SCD and ELOVL6), amino acid metabolism, the urea cycle (PAH, BCKDHA and OTC), glycolysis (PDK1 and PFKM) and lipid metabolism (ACAT2). Stage of hibernation (torpid vs aroused) had a much smaller effect, with only one gene associated with glycogen synthesis (GSY1) in liver showing consistent differences in expression levels between temperature treatments. Despite the more than eightfold increase in energetic demand associated with defending Tb during torpor at a Ta of –10 vs +2°C, transcript levels in liver and brown adipose tissue differed little. Our results are inconsistent with a hypothesized switch to use of non-lipid fuels when ambient temperatures drop below freezing.
Reversible remodeling of lung tissue during hibernation in the Syrian hamster
Authors: Talaei Fatemeh , Hylkema Machteld N. , Bouma Hjalmar R. , Boerema Ate S. , Strijkstra Arjen M. , Henning Rob H. , Schmidt Martina 
Published: March 2011

SUMMARYDuring hibernation, small rodents such as hamsters cycle through phases of strongly suppressed metabolism with low body temperature (torpor) and full restoration of metabolism and body temperature (arousal). Remarkably, the repetitive stress of cooling–rewarming and hypoxia does not cause irreversible organ damage. To identify adaptive mechanisms protecting the lungs, we assessed histological changes as well as the expression and localization of proteins involved in tissue remodeling in lungs from Syrian hamsters at different phases of hibernation using immunohistochemical staining and western blot analysis. In torpor (early and late) phase, a reversible increased expression of smooth muscle actin, collagen, angiotensin converting enzyme and transforming growth factor-β was found, whereas expression of the epidermal growth factor receptor and caveolin-1 was low. Importantly, all these alterations were restored during arousal. This study demonstrates substantial alterations in protein expression mainly in epithelial cells of lungs from hibernating Syrian hamsters. These structural changes of the bronchial airway structure are termed airway remodeling and often occur in obstructive lung diseases such as asthma, chronic obstructive pulmonary disease (COPD) and lung fibrosis. Unraveling the molecular mechanism leading to reversal of airway remodeling by the end of torpor may identify possible therapeutic targets to reduce progression of this process in patients suffering from asthma, chronic obstructive pulmonary disease and lung fibrosis.
Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) show microstructural bone loss during hibernation but preserve bone macrostructural geometry and strength
Authors: McGee-Lawrence Meghan E. , Stoll Danielle M. , Mantila Emily R. , Fahrner Bryna K. , Carey Hannah V. , Donahue Seth W. 
Published: March 2011

SUMMARY
Lack of activity causes bone loss In most animals. Hibernating bears have physiological processes to prevent cortical and trabecular bone loss associated with reduced physical activity, but different mechanisms of torpor among hibernating species may lead to differences in skeletal responses to hibernation. There are conflicting reports regarding whether small mammals experience bone loss during hibernation. To investigate this phenomenon, we measured cortical and trabecular bone properties in physically active and hibernating juvenile and adult 13-lined ground squirrels (Ictidomys tridecemlineatus, previous genus name Spermophilus). Cortical bone geometry, strength and mineral content were similar in hibernating compared with active squirrels, suggesting that hibernation did not cause macrostructural cortical bone loss. Osteocyte lacunar size increased (linear regression, P=0.001) over the course of hibernation in juvenile squirrels, which may indicate an osteocytic role in mineral homeostasis during hibernation. Osteocyte lacunar density and porosity were greater (+44 and +59%, respectively; P&lt;0.0001) in hibernating compared with active squirrels, which may reflect a decrease in osteoblastic activity (per cell) during hibernation. Trabecular bone volume fraction in the proximal tibia was decreased (–20%; P=0.028) in hibernating compared with physically active adult squirrels, but was not different between hibernating and active juvenile squirrels. Taken together, these data suggest that 13-lined ground squirrels may be unable to prevent microstructural losses of cortical and trabecular bone during hibernation, but importantly may possess a biological mechanism to preserve cortical bone macrostructure and strength during hibernation, thus preventing an increased risk of bone fracture during remobilization in the spring.
Consumer Understanding of Prescription Drug Information: An Illustration Using an Antidepressant Medication
Authors: Shiffman Saul , Gerlach Karen K , Sembower Mark A , Rohay Jeffrey M 
Published: March 2011

Background Patient education and warnings have emerged as prominent interventions for improving drug safety. As part of the provision of information and guidance on safe use of drugs, patients often receive multiple pieces of written information when they obtain a prescription medication, including a Food and Drug Administration (FDA)–mandated medication guide (MG), consumer medication information (CMI), and patient package insert (PPI). Objective: To determine whether patients understand the materials providing drug information and whether the materials convey the intended information. Methods: Fifty-two adults with a high school education or less were shown an actual (blinded) MG, CMI, and PPI for a marketed antidepressant medication. Comprehension was tested with methods used by the FDA to assess label comprehension for nonprescription products. Results: The majority of participants (88.2%) looked at all 3 pieces of information provided. The mean (SD) time spent reviewing the CMI was 5.2 (4.8) minutes (range 0-21.9). 16.5(13.3) minutes for the PPI (range 0-43.0), and 2.5 (1.6) minutes for the MG (range 0-7.6). Less than 20% of participants were able to identify the symptoms of a rare but potentially life-threatening situation that can occur with this medication and only 61.5% recalled the risk of teen suicide, which is the sole focus of the MG. Respondents with lower literacy scores performed more poorly than those with higher literacy scores. Conclusions: Information provided with at least some prescription drugs is not adequately understood by less-educated consumers and does not effectively communicate critical safety messages or directions.
The Role of Angiotensin Receptor Blockers in Patients with Angiotensin-Converting Enzyme Inhibitor-Induced Angioedema
Authors: Beavers Craig James , Dunn Steven P , Macaulay Tracy E 
Published: March 2011

Objective: To assess the safety of using angiotensin II receptor blockers (ARBs) in patients who develop angioedema with the use of angiotensin-converting enzyme inhibitors (ACEIs). Data Sources: A literature search was performed using MEDLINE (1977-January 2011) and Cochrane Library, using the terms angiotensin receptor blocker, angiotensin-converting enzyme inhibitor, and angioedema. In addition, reference citations from publications identified were reviewed. Study Selection and Data Extraction: Only English-language publications were included. Randomized controlled trial data, observational studies (retrospective and prospective), and case reports on adults who received ACEI therapy and then an ARB as an alternative therapy were reviewed. Data Synthesis: Two randomized controlled trials and 1 meta-analysis evaluated ARB use in patients intolerant to ACEIs. Taken together, there is a conservative estimate of a 10% or less incidence of cross reactivity of angioedema in patients who receive an ARB after experiencing ACEI-associated angioedema. Angioedema related to ARBs is reported to be less severe and occurs earlier compared to angioedema that develops during ACEI therapy Conclusions: ARBS may be an alternative for patients who develop angioedema white using an ACEI but should be reserved for patients with high therapeutic need for angiotensin inhibition. Treatment should be started with observation, patients should be educated on the signs of angioedema, and proper emergency management should be emphasized to patients and care providers.
Prevalence of Blood Doping in Samples Collected from Elite Track and Field Athletes
Authors: Sottas Pierre-Edouard , Robinson Neil , Fischetto Giuseppe , Dollé Gabriel , Alonso Juan Manuel , Saugy Martial 
Published: March 2011

BACKGROUND
No reliable estimate of the prevalence of doping in elite sports has been published. Since 2001, the international governing body for athletics has implemented a blood-testing program to detect altered hematological profiles in the world's top-level athletes.

METHODS
A total of 7289 blood samples were collected from 2737 athletes out of and during international athletic competitions. Data were collected in parallel on each sample, including the age, sex, nationality, and birth date of the athlete; testing date; sport; venue; and instrument technology. Period prevalence of blood-doping in samples was estimated by comparing empirical cumulative distribution functions of the abnormal blood profile score computed for subpopulations with stratified reference cumulative distribution functions.

RESULTS
In addition to an expected difference between endurance and nonendurance athletes, we found nationality to be the major factor of heterogeneity. Estimates of the prevalence of blood doping ranged from 1% to 48% for subpopulations of samples and a mean of 14% for the entire study population. Extreme cases of secondary polycythemia highlighted the health risks associated with blood manipulations.

CONCLUSIONS
When applied at a population level, in this case the population of samples, hematological data can be used to estimate period prevalence of blood doping in elite sports. We found that the world's top-level athletes are not only heterogeneous in physiological and anthropometric factors but also in their doping behavior, with contrasting attitudes toward doping between countries. When applied at the individual level, the same biomarkers, as formalized in the Athlete Biological Passport paradigm, can be used in analysis of the observed different physiological characteristics and behavioral heterogeneities.
Screening for small molecule modulators of Hsp70 chaperone activity using protein aggregation suppression assays: inhibition of the plasmodial chaperone PfHsp70-1
Authors: Cockburn Ingrid L. , Pesce Eva-Rachele , Pryzborski Jude M. , Davies-Coleman Michael T. , Clark Peter G.K. , Keyzers Robert A. , Stephens Linda L. , Blatch Gregory L. 
Published: March 2011

Abstract

Plasmodium falciparum heat shock protein 70 (PfHsp70-1) is thought to play an essential role in parasite survival and virulence in the human host, making it a potential antimalarial drug target. A malate dehydrogenase based aggregation suppression assay was adapted for the screening of small molecule modulators of Hsp70. A number of small molecules of natural (marine prenylated alkaloids and terrestrial plant naphthoquinones) and related synthetic origin were screened for their effects on the protein aggregation suppression activity of purified recombinant PfHsp70-1. Five compounds (malonganenone A-C, lapachol and bromo-β-lapachona) were found to inhibit the chaperone activity of PfHsp70-1 in a concentration dependent manner, with lapachol preferentially inhibiting PfHsp70-1 compared to another control Hsp70. Using growth inhibition assays on P. falciparum infected erythrocytes, all of the compounds, except for malonganenone B, were found to inhibit parasite growth with IC50 values in the low micromolar range. Overall, this study has identified two novel classes of small molecule inhibitors of PfHsp70-1, one representing a new class of antiplasmodial compounds (malonganenones). In addition to demonstrating the validity of PfHsp70-1 as a possible drug target, the compounds reported in this study will be potentially useful as molecular probes for fundamental studies on Hsp70 chaperone function.
Stream channel network analysis applied to colony-wide feeding structures in a Permian bryozoan from Greenland
Authors: Key Marcus M. , Jackson Patrick N. Wyse , Vitiello Louis J. 
Published: March 2011

Colony-wide feeding currents are a common feature of many bryozoan colonies. These feeding currents are centered on excurrent macular chimneys that expel previously filtered water away from the colony surface. In some bryozoans these macular chimneys consist of a branching channel network that converges at a point in the center of the chimney. The bifurcating channels of the maculae are analogous to a stream channel network in a closed basin with centripetal drainage. The classical methods of stream channel network analysis from geomorphology are here used to quantitatively analyze the number and length of macular channels in bryozoans. This approach is applied to a giant branch of the trepostome bryozoanTabuliporafrom the Early Permian Kim Fjelde Formation in North Greenland. Its large size allowed 18 serial tangential peels to be made through the 8-mm-thick exozone. The peels intersected two stellate maculae as defined by contiguous exilapores. The lengths of 1460 channels radiating from the maculae were measured and their Horton-Strahler stream order and Shreve magnitude scored.We hypothesize that if fossil bryozoan maculae function as excurrent water chimneys, then they should conform to Horton's laws of stream networks and behave like closed basins with centripetal drainage. Results indicate that the stellate maculae in this bryozoan behaved liked stream channel networks exhibiting landscape maturation and stream capture. They conformed to the Law of Stream Number. They have a Bifurcation Ratio that falls within the range of natural stream channel networks. They showed a pattern opposite that expected by the Law of Stream Lengths in response to behavior characteristic of a centripetal drainage pattern in a closed basin. Thus, the stellate maculae in this bryozoan probably functioned as excurrent water chimneys with the radiating channels serving to efficiently collect the previously filtered water, conducting it to the central chimney for expulsion away from the colony surface.
Impact of Globalization on Income Distribution Inequality in 60 Countries
Authors: Zhou Lei , Biswas Basudeb , Bowles Tyler , Saunders Peter J. 
Published: March 2011

This paper investigates the impact of globalization on income inequality distribution in 60 developed, transitional, and developing countries. Using Kearney's (2002, 2003 and 2004) data and principal component analysis (PCA), two globalization indices are created. One of these indices is the equally weighted index. The other index is derived from the principal component analysis. The Gini coefficient of a country is regressed on each index, respectively, in all 60 test cases. The main contribution of this paper is its finding of a negative relationship between both globalization indices and the Gini coefficient for all 60 countries under investigation. Furthermore, test results indicate that this relationship is robust. Therefore, the empirical evidence presented in this paper supports the claim that globalization helps reduce income distribution inequality within countries.