bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endothelial cell expression of tissue factor in sickle mice is augmented by hypoxia/reoxygenation and inhibited by lovastatin
Authors: Solovey Anna , Kollander Rahn , Shet Arun , Milbauer Liming C. , Choong Stephana , Panoskaltsis-Mortari Angela , Blazar Bruce R. , Kelm Robert J. , Hebbel Robert P. 
Published: April 2004

AbstractAbnormal tissue factor (TF) expression has been demonstrated on blood monocytes and circulating endothelial cells in humans with sickle cell anemia. We have now studied sickle transgenic mice to help define the biology of endothelial TF expression in sickle disease. Using immunostaining of tissue sections, we find that this is confined almost exclusively to the pulmonary veins. About 15% and 13% of these exhibit TF-positive endothelium in the wild-type normal mouse and the normal human hemoglobin (HbA)–expressing control transgenic mouse, respectively. The mild sickle mouse is indistinguishable from normal (∼ 14% positive), but TF expression is significantly elevated in the moderate and severe mouse models of sickle disease (∼ 29% and ∼ 41% positive, respectively). Exposure of the mild sickle mouse to hypoxia for 3 hours, followed by reoxygenation, converted its TF expression phenotype to that of the severe sickle mouse (∼ 36% positive). Pretreatment with lovastatin eliminated excessive expression of TF in the posthypoxic mild sickle mouse (∼ 16% positive) and in the more severe mouse at ambient air (∼ 21% positive). In addition to identifying tissue expression of endothelial TF in the sickle lung, these studies implicate reperfusion injury physiology in its expression and suggest a rationale for use of statins in sickle disease.
Cytolytic activity and regulatory functions of inhibitory NK cell receptor–expressing T cells expanded from granulocyte colony-stimulating factor–mobilized peripheral blood mononuclear cells
Authors: Tanaka Junji , Toubai Tomomi , Tsutsumi Yutaka , Miura Yoko , Kato Naoko , Umehara Shintarou , Kahata Kaoru , Mori Akio , Toyoshima Nobuyasu , Ota Shuichi , Kobayashi Takahiko , Kobayashi Masanobu , Kasai Masaharu , Asaka Masahiro , Imamura Masahiro 
Published: April 2004

AbstractInhibitory natural killer cell receptor (NKR)–expressing cells may induce a graft-versus-leukemia/tumor (GVL/T) effect against leukemic cells and tumor cells that have mismatched or decreased expression of HLA class I molecules and may not cause graft-versus-host disease (GVHD) against host cells that have normal expression of HLA class I molecules. In our study, we were able to expand inhibitory NKR (CD94/NKG2A)–expressing CD8+ T cells from granulocyte colonystimulating factor (G-CSF)–mobilized peripheral blood mononuclear cells (G-PBMCs) by more than 500-fold using stimulation by an anti-CD3 monoclonal antibody with interleukin 15 (IL-15). These expanded and purified CD94-expressing cells attacked various malignant cell lines, including solid cancer cell lines, as well as the patients' leukemic cells but not autologous and allogeneic phytohemagglutinin (PHA) blasts in vitro. Also, these CD94-expressing cells prevented the growth of K562 leukemic cells and CW2 colon cancer cells in NOD/SCID mice in vivo. On the other hand, the CD94-expressing cells have low responsiveness to alloantigen in mixed lymphocyte culture (MLC) and have high transforming growth factor (TGF)–β1– but low IL-2– producing capacity. Therefore, CD94-expressing cells with cytolytic activity against the recipient's leukemic and tumor cells without enhancement of alloresponse might be able to be expanded from donor G-PBMCs.
Fibrin-incorporated vitronectin is involved in platelet adhesion and thrombus formation through homotypic interactions with platelet-associated vitronectin
Authors: Wu Ya-Ping , Bloemendal Haiko J. , Voest Emile E. , Logtenberg Ton , de Groot Philip G. , Gebbink Martijn F. B. G. , de Boer Hetty C. 
Published: April 2004

AbstractWhen a blood clot is formed, vitronectin (VN) is incorporated. Here we studied the consequence of VN incorporation for platelet interactions under flow. Perfusion of whole blood over a fibrin network, formed from purified fibrinogen, resulted in approximately 20% surface coverage with blood platelets. Incorporation of purified multimeric VN into the fibrin network resulted in a 2-fold increase in surface coverage with platelets and in enhancement of platelet aggregate formation. A human monoclonal antibody (huMab VN18), directed against the multimeric form of VN, inhibited platelet adhesion to the combined fibrin/VN matrix to the level of adhesion on fibrin alone. This inhibition was also shown when whole blood was perfused over a plasma-derived clot. Surprisingly, the inhibitory action of the antibody was not directed toward VN incorporated into the fibrin network but toward VN released from the platelets. We conclude that VN-potentiated platelet-clot interaction requires VN in the clot and multimeric VN bound to the platelet surface. Our results provide evidence that homotypic VN interactions contribute to platelet adhesion and aggregation to a blood clot. This report demonstrates for the first time that self-assembly of VN may provide a physiologically relevant contribution to platelet aggregation on a blood clot.
Case report: Purple urine bag syndrome
Authors: Ribeiro Joaquim Palmeiro , Marcelino Paulo , Marum Susan , Fernandes Ana Paula , Grilo Ana 
Published: April 2004

AbstractPurple urine bag syndrome (PUBS) was first reported in 1978. PUBS is rare, occurs predominantly in constipated women, chronically catheterized and associated with some bacterial urinary infections that produce sulphatase/phosphatase. The etiology is due to indigo (blue) and indirubin (red) or to their mixture that becomes purple. A chain reaction begins in the gastrointestinal tract with tryptophan as described in the article.
Growth Hormone Alters Epidermal Growth Factor Receptor Binding Affinity via Activation of Extracellular Signal-Regulated Kinases in 3T3-F442A Cells
Authors: Huang Yao , Chang Yongchang , Wang Xiangdong , Jiang Jing , Frank Stuart J. 
Published: April 2004

AbstractEpidermal growth factor receptor (EGFR) is a transmembrane protein that binds EGF in its extracellular domain and initiates signaling via intrinsic tyrosine kinase activity in its cytoplasmic domain. EGFR is important in development, cellular proliferation, and cancer. GH is a critical growthpromoting and metabolic regulatory hormone that binds the GH receptor, thereby engaging various signaling pathways, including ERKs. Prior studies suggest cross-talk between the GH receptor and EGFR signaling systems. Using the GH- and EGF-responsive 3T3-F442A preadipocyte, we previously observed that GH, in addition to causing EGFR tyrosine phosphorylation, also induced EGFR phosphorylation that was detected by PTP101, an antibody reactive with ERK consensus phosphorylation sites. This latter phosphorylation was prevented by pretreatment with MAPK kinase (MEK)1 inhibitors, suggesting ERK pathway dependence. Furthermore, GH cotreatment with EGF markedly slowed EGF-induced EGFR degradation and down-regulation, thereby potentiating EGF-induced EGFR signaling. These effects were also MEK1 dependent and suggested ERK pathway-dependent influence of GH on EGF-induced EGFR postendocytic trafficking and signaling. We now explore the impact of GH on cell surface binding of EGF in 3T3-F442A cells. We found that GH pretreatment caused transient, but substantial, lessening of 125I-EGF binding. Competitive binding experiments revealed that the decreased binding was primarily due to decreased affinity, rather than a change in the number of EGF binding sites. The effect of GH on EGF binding was concentration dependent and temporally correlated with GH-induced ERK activation and EGFR PTP101-reactive phosphorylation. Blockade of the MEK1/ERK but not the protein kinase C pathway, prevented GH’s effects on EGF binding, and our results indicate that the mechanisms of GH- and phorbol-12-myristate-13-acetateinduced inhibition of EGF binding differ substantially. Overall, our findings suggest that GH can modulate both EGF binding kinetics and the EGFR’s postbinding signaling itinerary in a MEK1/ERK pathway-dependent fashion.
Paradox lost: answers and questions about walking on water
Authors: Denny Mark W. 
Published: April 2004

SUMMARY
The mechanism by which surface tension allows water striders (members of the genus Gerris) to stand on the surface of a pond or stream is a classic example for introductory classes in animal mechanics. Until recently,however, the question of how these insects propelled themselves remained open. One plausible mechanism–creating momentum in the water via the production of capillary waves–led to a paradox: juvenile water striders move their limbs too slowly to produce waves, but nonetheless travel across the water's surface. Two recent papers demonstrate that both water striders and water-walking spiders circumvent this paradox by foregoing any reliance on waves to gain purchase on the water. Instead they use their legs as oars, and the capillary `dimple' formed by each leg acts as the oar's blade. The resulting hydrodynamic drag produces vortices in the water, and the motion of these vortices imparts the necessary fluid momentum. These studies pave the way for a more thorough understanding of the complex mechanics of walking on water, and an exploration of how this intriguing form of locomotion scales with the size of the organism.
Dynamin-association with agonist-mediated sequestration of beta-adrenergic receptor in single-cell eukaryoteParamecium
Authors: Wiejak Jolanta , Surmacz Liliana , Wyroba Elzbieta 
Published: April 2004

SUMMARYEvidence that dynamin is associated with the sequestration of the Paramecium β2-adrenergic receptor (βAR)immunoanalogue is presented. We previously reported a dramatic change in the distribution of βAR analogue in the subcellular fractions upon isoproterenol treatment: it is redistributed from the membraneous to the cytosolic fraction, as revealed by quantitative image analysis of western blots. Here we confirm and extend this observation by laser scanning confocal and immunogold electron microscopy. In the presence of isoproterenol (10μmol l–1) βAR translocated from the cell surface into dynamin-positive vesicles in the cytoplasmic compartment, as observed by dual fluorochrome immunolabeling in a series of the confocal optical sections. Colocalization of βAR and dynamin in the tiny endocytic vesicles was detected by further electron microscopic studies.Generally receptor sequestration follows its desensitization, which is initiated by receptor phosphorylation by G-protein-coupled receptor kinase. We cloned and sequenced the gene fragment of 407 nucleotides homologous to theβ-adrenergic receptor kinase (βARK): its deduced amino acid sequence shows 51.6% homology in 126 amino acids that overlap with the human βARK2(GRK3), and may participate in Paramecium βAR desensitization.These results suggest that the molecular machinery for the desensitization/sequestration of the receptor immunorelated to vertebrateβAR exists in unicellular Paramecium.
Nitrogen stress causes unpredictable enrichments of 15N in two nectar-feeding bat species
Authors: Voigt Christian C. , Matt Felix 
Published: April 2004

SUMMARY
We estimated the effect of nitrogen stress on the nitrogen isotope enrichments in wing membrane and blood of two nectar-feeding bats(Glossophaga soricina and Leptonycteris curasoae) by offering a nitrogen-poor diet with a high δ15N andδ 13C. Before the experiment, bats were sustained on a normal diet with a low δ15N and δ13C. Under this first food regime, the fractionation of nitrogen isotopes averaged 3.1‰δ 15N for blood and 4.4‰ δ15N for wing membrane, which was almost twice as high as the corresponding fractionation of carbon isotopes. After switching to the nitrogen-poor diet, the enrichment of heavy isotopes increased for both elements in all tissues under study. The recently published estimates of half-life of carbon isotopes indicated a low turnover rate of carbon in wing membrane and blood and an almost constant half-life over varying losses of body mass. The estimates of half-life of nitrogen were two to six times higher than those of carbon. We argue that this discrepancy was caused by the mixing of nitrogen isotopes from internal and external sources. The mixing effect was probably negligible for carbon as the amount of ingested carbon outweighed the amount of mobilized carbon from internal sources. A correlation between the estimated turnover rates of nitrogen and losses of body masses was probably obscured by the additional fractionation of nitrogen isotopes in catabolic animals. We conclude that the interpretation of nitrogen isotope data of free-ranging animals is difficult when the animal's diet is changing to a critical nitrogen content.
Mechanisms of K+ transport across basolateral membranes of principal cells in Malpighian tubules of the yellow fever mosquito,Aedes aegypti
Authors: Scott Brett N. , Yu Ming-Jiun , Lee Lenora W. , Beyenbach Klaus W. 
Published: April 2004

SUMMARYThe mechanisms of K+ entry from the hemolymph into principal cells of Malpighian tubules were investigated in the yellow fever mosquito, Aedes aegypti. The K+ channel blocker Ba2+ (5 mmol l–1) significantly decreased transepithelial (TEP) fluid secretion (Vs) from 0.84 nl min–1 to 0.37 nl min–1 and decreased the K+ concentration in secreted fluid from 119.0 mmol l–1 to 54.3 mmol l–1 with no change in the Cl– concentration. Even though the Na+ concentration increased significantly from 116.8 mmol l–1 to 144.6 mmol l–1, rates of TEP ion secretion significantly decreased for all three ions. In addition,Ba2+ had the following significant electrophysiological effects: it depolarized the TEP voltage (Vt) from 19.4 mV to 17.2 mV,increased the TEP resistance (Rt) from 6.4 kΩcm to 6.9 kΩcm, hyperpolarized the basolateral membrane voltage of principal cells (Vbl) from –75.2 mV to –88.2 mV and increased the cell input resistance from 363.7 kΩ to 516.3 kΩ. These effects of Ba2+ reflect the block of K+ channels that, apparently, are also permeable to Na+. Bumetanide (100μmol l–1) had no effect on TEP fluid secretion and electrical resistance but significantly decreased TEP K+ secretion,consistent with the inhibition of electroneutral Na+/K+/2Cl– cotransport. TEP Na+ secretion significantly increased because other Na+entry pathways remained active. Bumetanide plus Ba2+ completely inhibited TEP electrolyte and fluid secretion, with fast and slow kinetics reflecting the Ba2+ block of basolateral membrane K+channels and the inhibition of Na+/K+/2Cl– cotransport, respectively. The single and combined effects of Ba2+ and bumetanide suggest that(1) K+ channels and Na+/K+/2Cl– cotransport are the primary mechanisms for bringing K+ into cells, (2) K+ channels mediate a significant Na+ influx, (3) Na+ has as many as four entry pathways and (4) the mechanisms of TEP K+ and Na+ secretion are coupled such that complete block of TEP K+ renders the epithelium unable to secrete Na+.
Wing inertia and whole-body acceleration: an analysis of instantaneous aerodynamic force production in cockatiels (Nymphicus hollandicus)flying across a range of speeds
Authors: Hedrick Tyson L. , Usherwood James R. , Biewener Andrew A. 
Published: April 2004

SUMMARYWe used a combination of high-speed 3-D kinematics and three-axis accelerometer recordings obtained from cockatiels flying in a low-turbulence wind tunnel to characterize the instantaneous accelerations and, by extension,the net aerodynamic forces produced throughout the wingbeat cycle across a broad range of flight speeds (1–13 m s–1). Our goals were to investigate the variation in instantaneous aerodynamic force production during the wingbeat cycle of birds flying across a range of steady speeds, testing two predictions regarding aerodynamic force generation in upstroke and the commonly held assumption that all of the kinetic energy imparted to the wings of a bird in flapping flight is recovered as useful aerodynamic work. We found that cockatiels produce only a limited amount of lift during upstroke (14% of downstroke lift) at slower flight speeds(1–3 m s–1). Upstroke lift at intermediate flight speeds (7–11 m s–1) was moderate, averaging 39% of downstroke lift. Instantaneous aerodynamic forces were greatest near mid-downstroke. At the end of each half-stroke, during wing turnaround,aerodynamic forces were minimal, but inertial forces created by wing motion were large. However, we found that the inertial power requirements of downstroke (minimum of 0.29±0.10 W at 7 m s–1 and maximum of 0.56±0.13 W at 1 m s–1) were consistent with the assumption that nearly all wing kinetic energy in downstroke was applied to the production of aerodynamic forces and therefore should not be added separately to the overall power cost of flight. The inertial power requirements of upstroke (minimum of 0.16±0.04 W at 7 m s–1 and maximum of 0.35±0.11 W at 1 m s–1) cannot be recovered in a similar manner, but their magnitude was such that the power requirements for the upstroke musculature(minimum of 54±13 W kg–1 at 7 m s–1and maximum of 122±35 W at 1 m s–1) fall within the established range for cockatiel flight muscle (&lt;185 W kg–1).
Marked load-bearing ability ofMytilussmooth muscle in both active and catch states as revealed by quick increases in load
Authors: Mukou Masao , Kishi Hirohiko , Shirakawa Ibuki , Kobayashi Takakazu , Tominaga Katsutoshi , Imanishi Haruka , Sugi Haruo 
Published: April 2004

SUMMARYThe anterior byssal retractor muscle (ABRM) of the bivalve Mytilus edulis shows a prolonged tonic contraction, called the catch state. To investigate the catch mechanism, details of which still remain obscure, we studied the mechanical responses of ABRM fibres to quick increases in load applied during maximum active isometric force (P0)generation and during the catch state. The mechanical response consisted of three components: (1) initial extension of the series elastic component (SEC),(2) early isotonic fibre lengthening with decreasing velocity, and (3) late steady isotonic fibre lengthening. The ABRM fibres could bear extremely large loads up to 10–15P0 for more than 30–60 s,while being lengthened extremely slowly. If, on the other hand, quick increases in load were applied during the early isometric force development,the ABRM fibres were lengthened rapidly (`give') under loads of 1.5–2P0. These findings might possibly be explained by two independent systems acting in parallel with each other; one is the actomyosin system producing active shortening and active force generation,while the other is the load-bearing system responsible for the extremely marked load-bearing ability as well as the maintenance of the catch state.
Stress gene (hsp70) sequences and quantitative expression inMilnesium tardigradum(Tardigrada) during active and cryptobiotic stages
Authors: Schill Ralph O. , Steinbrück Günther H. B. , Köhler Heinz-R. 
Published: April 2004

SUMMARYThe eutardigrade Milnesium tardigradum can undergo cryptobiosis,i.e. entry into a reversible ametabolic stage induced by dehydration, cooling and, probably, osmotic and anoxic stress. For the first time in tardigrades,we described partial sequences of three heat-shock protein (hsp70family) genes and examined gene expression on the way from an active to a cryptobiotic and back to an active stage again. Results showed different patterns of gene expression in the hsp70 isoforms. All three isoforms seem to be true heat-shock proteins since transcription could be clearly enhanced by temperature elevation. Isoform 1 and, at a lower level, isoform 3 do not seem to have a specific function for cryptobiosis. By contrast,transcription of isoform 2 is significantly induced in the transitional stage between the active and the cryptobiotic stage, resulting in a comparatively high mRNA copy number also during cryptobiosis. This pattern of induction implies that isoform 2 is the most relevant hsp70 gene for M. tardigradum individuals entering the cryptobiotic stage.
Effects of mass distribution on the mechanics of level trotting in dogs
Authors: Lee David V. , Stakebake Eric F. , Walter Rebecca M. , Carrier David R. 
Published: April 2004

SUMMARYThe antero–posterior mass distribution of quadrupeds varies substantially amongst species, yet the functional implications of this design characteristic remain poorly understood. During trotting, the forelimb exerts a net braking force while the hindlimb exerts a net propulsive force. Steady speed locomotion requires that braking and propulsion of the stance limbs be equal in magnitude. We predicted that changes in body mass distribution would alter individual limb braking–propulsive force patterns and we tested this hypothesis by adding 10% body mass near the center of mass, at the pectoral girdle, or at the pelvic girdle of trotting dogs. Two force platforms in series recorded fore- and hindlimb ground reaction forces independently. Vertical and fore–aft impulses were calculated by integrating individual force–time curves and Fourier analysis was used to quantify the braking–propulsive (b–p) bias of the fore–aft force curve. We predicted that experimental manipulation of antero–posterior mass distribution would (1) change the fore–hind distribution of vertical impulse when the limb girdles are loaded, (2) decrease the b–p bias of the experimentally loaded limb and (3) increase relative contact time of the experimentally loaded limb, while (4) the individual limb mean fore–aft forces (normalized to body weight + added weight) would be unaffected. All four of these results were observed when mass was added at the pelvic girdle,but only 1, 3 and 4 were observed when mass was added at the pectoral girdle. We propose that the observed relationship between antero–posterior mass distribution and individual limb function may be broadly applicable to quadrupeds with different body types. In addition to the predicted results,our data show that the mechanical effects of adding mass to the trunk are much more complex than would be predicted from mass distribution alone. Effects of trunk moments due to loading were evident when mass was added at the center of mass or at the pelvic girdle. These results suggest a functional link between appendicular and axial mechanics via action of the limbs as levers.