bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stereoselectivity of the reduced folate carrier in Caco‐2 cells
Authors: Narawa Tomoya , Shimizu Rikako , Takano Shuhei , Tsuda Yasuyuki , Ono Kiyoko , Yamada Hideo , Itoh Tomoo 
Published: August 2005

AbstractStereoselectivity of the human reduced folate carrier (RFC1) was examined in Caco‐2 cells using methotrexate (l‐amethopterin or l‐MTX) and its antipode (d‐amethopterin or d‐MTX) as model substrates. The initial uptake rate of folic acid (FA) was concentration dependent, with a Km value of approximately 0.6 μM. The Eadie–Hofstee plot of the RFC1‐mediated FA uptake revealed a single component for FA uptake into Caco‐2 cells, demonstrating that only RFC1 is involved in FA uptake. l‐MTX inhibited FA uptake in a competitive manner with a Ki value of approximately 2 μM, similar to the Km value of l‐MTX. d‐MTX also competitively inhibited FA uptake with a Ki value being approximately 120 μM, indicating that the affinity of d‐MTX is ca. 60‐fold less than that of l‐MTX. The stereoselectivity of human RFC1 observed in the present study was consistent not only with the stereoselectivity of rabbit RFC1 observed in rabbit intestinal brush border membrane vesicles but also with the reported differences in oral absorption of amethopterin enantiomers in humans. © 2005 Wiley‐Liss, Inc. Chirality 17:444–449, 2005.
Chiral separation and CD characterisation of enantiomeric cyclotriphosphazene derivatives
Authors: Bui Tam T.T. , Coles Simon J. , Davies David B. , Drake Alex F. , Eaton Robert J. , Hursthouse Michael B. , Kılıç Adem , Shaw Robert A. , Yeşilot Serkan 
Published: August 2005

AbstractThe gem‐disubstituted cyclotriphosphazene 1 reacted with piperazine (pip) to give the piperazine‐bridged derivative 2, which is expected to exist in meso and racemic forms because the two PCl (pip) groups are stereogenic. The proton‐decoupled 31P NMR spectrum of 2 gave rise to two similar sets of ABX signals in a 1:1 ratio, consistent with formation of diastereoisomers. The meso and racemic forms of compound 2 were separated by column chromatography on silica gel and characterised by elemental analysis, mass spectrometry, 31P NMR spectroscopy, and X‐ray crystallography. Using HPLC with a chiral stationary phase, the racemic form of compound 2 was further separated into enantiomers, which were characterised by circular dichroism (CD) spectroscopy. This is the first report of the separation of enantiomers in the field of cyclophosphazene chemistry and hence the first CD spectra of derivatives in which the cyclophosphazene ring is at the chiral centre. © 2005 Wiley‐Liss, Inc. Chirality 17:438–443, 2005.
Conformational Control of Calix[6]arenes Through Multiple Bridges
Authors: Galán Hitos , de Mendoza Javier , Prados Pilar 
Published: August 2005

AbstractThe synthesis of the A,D‐m‐xylylene‐bridged B,C,E,F‐tetra‐O‐alkylcalix[6]arenes 1b–c and the A,D‐B,C;E,F‐triply bridged calix[6]arenes 2a–c is described. The cone conformation of the new bridged calix[6]arenes has been established by a full set of 1D/2D 1H and 13C NMR techniques. These compounds are substantially more rigid than calix[6]arene analogues with an A,D‐p‐xylylene bridge, and the resulting cavities are better defined. Molecular mechanics optimization of triply bridged calix[6]arenes 2b and 2c resulted in structures fully consistent with the NMR spectra. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis of High Molecular Weight Amphiphilic Polyphenylenes by Suzuki Polycondensation
Authors: Kandre Ramchandra M. , Kutzner Fabian , Schlaad Helmut , Schlüter A. Dieter 
Published: August 2005

AbstractSummary: Four different 1,4‐ and 1,3‐dibromobenzenes carrying nonpolar dodecyloxy and linear as well as branched polar oligo(ethylene glycol) side chains were subjected to Suzuki polycondensation (SPC) with benzene‐1,4‐bisboronic acid ester to produce high‐molecular‐weight amphiphilic polyphenylenes, three of which are all‐para and one is meta linked. Molecular weights were determined by size exclusion chromatography with conventional polystyrene calibration and, for two selected samples, with universal calibration. Polymerization under SPC conditions of one of the 1,4‐dibromo monomers is compared to that of the direct 1,4‐diiodo analog.Polyphenylenes prepared in this study.imagePolyphenylenes prepared in this study.
The cytoskeleton‐dependent localization of cdc2/cyclin B in blastomere cortex during Xenopus embryonic cell cycle
Authors: Nakamura Norihiko , Tokumoto Toshinobu , Ueno Shuichi , Iwao Yasuhiro 
Published: August 2005

AbstractIn the early development of the frog, Xenopus laevis, blastomeres undergo synchronous divisions at about the 12th cell cycle, followed by asynchronous divisions, which is referred to as mid‐blastula transition (MBT). We investigated the distribution of several regulating factors for cell cycles around MBT using immunocytochemistry and confocal fluorescence microscopy. At the 8th cell cycle, most of the cdc2/cyclin B was localized in the cortical cytoplasm throughout the cell cycle, in the centrosomes and the nucleus at interphase and prometaphase, and in the spindles at metaphase and anaphase. Cdc2 was also localized in the chromatins at metaphase and anaphase. Cyclin B1 mRNA was localized in the periphery of the nucleus, but not in the cell cortex. At the 13th cell cycle, the amount of cdc2/cyclin B in the cortical cytoplasm decreased, and the inactive form of cdc2, phosphorylated at tyrosine 15, appeared in the nucleus and the centrosomes at interphase, indicating that the regulation of cdc2 by phosphorylation occurs around MBT. When the blastomeres were treated with nocodazole or latrunculin A at the 8th cell cycle, the amount of cortical cdc2 decreased, but that of cyclin B did not change. The cortical localization of cdc2 is dependent upon both microtubules and microfilaments. Most of the cdc27 was localized in the centrosomes, and in the spindle poles, but no significant difference was observed between the 8th and the 13th cell cycles. It is possible that the cortical MPF activity is regulated by the differential localization between cdc2 and cyclin B. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
Sensitivity analysis of partial differential equations: A case for functional sensitivity
Authors: Kabala Z. J. , Milly P. C. D. 
Published: August 2005

AbstractSensitivity analysis allows for analyzing the effects of parameter uncertainty. For functional parameters, the sensitivity of the system is described by the functional derivatives of the output variables with respect to the parameters. Approximation of each of the functional parameters by a finite number of scalars (via the finite element representation) allows one to use elementary sensitivity analysis. The functional sensitivities are easily approximated from elementary sensitivities and, being objective quantities, they allow one to evaluate the numerical quality of sensitivities. The grid density necessary for computing functional sensitivities may differ significantly from the grid required for the numerical solution of the governing equation.
Asymptotic factorization of evolution equations which involve linear operators
Authors: Cooke Charlie H. , McMorran Andrew G. 
Published: August 2005

AbstractOperator splitting for evolution equations which involve linear operators is investigated. A systematic method for identifying multifactor fractional‐step operator splittings is proposed. The classical second‐order accurate splittings of Strang readily emerge, as well as various third‐order splittings of nonstandard type. Factorizations possessing mixed positive‐negative fractional steps are discovered, as well as bizarre splittings whose factors include complex fractional steps. It is found that no higher‐order accurate splitting which employs all positive fractional steps and which possesses less than nine operator factors can exist. For the linear case this implies second‐order accurate splittings are optimal, as a further increase of one power in accuracy essentially requires a three‐fold increase in work. This estimate slightly improves, for cases where the nonstandard splittings can be employed. Some numerical experiments which illustrate the theory are provided.
Total dependence of the cerebral circulation on the right vertebral artery in Takayasu's disease—A case report
Authors: Elewaut Dirk S. , Duprez Daniel A. , De Buyzere Marc L. , Kunnen Marc F. , Clement Denis L. 
Published: August 2005

A twenty-four-year-old woman with Takayasu's disease was admitted in June 1992 to the hospital because of amaurosis fugax. There were neither a history of stroke nor other neurologic signs. For a long time the patient had suffered from extreme fatigue and claudication of the upper limbs. In 1988 arteriography revealed total occlusion of both subclavian arteries and a severe filiform stenosis of the left common carotid artery. The disease appeared to be stable between 1988 and 1992 without obvious signs of inflammation. At present arteriography additionally reveals total occlusion of both common carotid arteries and the left vertebral artery. Only the right vertebral artery is patent, although presenting clear stenosis at its origin. A computed tomographic scan of the brain appears normal.The progression of the disease in the absence of inflammatory episodes since 1988 and the total dependence of the cerebral arterial circulation on the right vertebral artery are the hallmarks of this very rare case of Takayasu's disease.
Plant–animal interactions in seagrass beds: ongoing and future challenges for understanding population and community dynamics
Authors: Nakaoka Masahiro 
Published: August 2005

AbstractSeagrass beds are some of the most productive parts of coastal ecosystems, hosting a wide variety of associated fauna. This paper reviews recent studies of animal–plant interactions in seagrass beds, focusing particularly on studies conducted in Japan and Thailand. Although the positive effect of seagrass habitat structure on animals has been widely acknowledged, the magnitude of this effect varies greatly among studies. A comparative study on epifaunal communities and a manipulative experiment using an infaunal bivalve revealed that behavioral and life‐history traits of component species and their interactions influence the observed variation. Some recent studies have challenged the previously accepted view that direct herbivory on seagrasses is rare, and has a minor effect on the seagrass community. A series of studies of dugong herbivory revealed that the marine mammal has great impacts not only on seagrass productivity but also on the infaunal community. Furthermore, it has been found that seed predators have a negative influence on seed production and the subsequent recruitment of seagrass. Recent studies have also demonstrated significant effects of fine‐scale landscape patterns in seagrass vegetation on productivity, species interactions and community structure in seagrass beds. Future research integrating new concepts and theories in ecology, such as metapopulation and hierarchy theories, with new research tools, such as molecular‐genetic analyses and remote‐sensing techniques, may aid in developing a more comprehensive understanding of population and community dynamics in seagrass beds.
Fear of pain, not pain catastrophizing, predicts acute pain intensity, but neither factor predicts tolerance or blood pressure reactivity: An experimental investigation in pain‐free individuals
Authors: George Steven Z. , Dannecker Erin A. , Robinson Michael E. 
Published: August 2005

AbstractPrevious studies of the Fear‐Avoidance Model of Exaggerated Pain Perception have commonly included patients with chronic low back pain, making it difficult to determine which psychological factors led to the development of an “exaggerated pain perception”. This study investigated the validity of the Fear‐Avoidance Model of Exaggerated Pain Perception by considering the influence of fear of pain and pain catastrophizing on acute pain perception, after considering sex and anxiety. Thirty‐two males and 34 females completed the State‐Trait Anxiety Inventory, the Fear of Pain Questionnaire, and the Coping Strategies Questionnaire. Subjects underwent a cold pressor procedure and tolerance, pain intensity, and blood pressure reactivity were measured. Sex, anxiety, fear of pain, and pain catastrophizing were simultaneously entered into separate multiple regression models to predict different components of pain perception. Tolerance was not predicted by fear of pain, pain catastrophizing, or anxiety. Pain intensity at threshold and tolerance were significantly predicted by fear of pain, only. Blood pressure reactivity to pain was significantly predicted by anxiety, only. These results suggest that fear of pain may have a stronger influence on acute pain intensity when compared to pain catastrophizing, while neither of the factors predicted tolerance or blood pressure reactivity.
Electroporation of the heart
Authors: Nikolski Vladimir P. , Efimov Igor R. 
Published: August 2005

Abstract
Defibrillation shocks are commonly used to terminate life-threatening arrhythmias. According to the excitation theory of defibrillation, such shocks are aimed at depolarizing the membranes of most cardiac cells resulting in resynchronization of electrical activity in the heart. If shock-induced changes in transmembrane potential are large enough, they can cause transient tissue damage due to electroporation. In this review evidence is presented that (a) electroporation of the heart tissue can occur during clinically relevant intensities of the external electrical field, and (b) electroporation can affect the outcome of defibrillation therapy; being both pro- and anti-arrhythmic.
Climate, zooplankton, and pelagic fish growth in the central Baltic Sea
Authors: Möllmann Christian , Kornilovs Georgs , Fetter Marina , Köster Friedrich W. 
Published: August 2005

Abstract
Oceanographic conditions in the brackish central Baltic Sea are strongly linked to atmospheric forcing and the unusual period of persistently strong westerlies that, since the late 1980s, have resulted in an increase in average water temperatures and decreasing salinity. These changes in temperature and salinity resulted in a change in the dominance of the mesozooplankton community from Pseudocalanus sp. to Temora longicornis and Acartia spp. Similar to the copepod community, the central Baltic fish community shifted from cod (Gadus morhua), dominant during the 1980s, to sprat (Sprattus sprattus), dominant during the 1990s. Further, the commercially important pelagic fish species herring (Clupea harengus) and sprat exhibited reductions in growth. Using Principal Component and Correlation Analyses we investigated the temporal variability in the importance of the food supply as well as competition on condition of central Baltic pelagic fish species. Our results indicate that herring condition results from a combined effect of changes in the food environment and increased competition with sprat, while sprat condition appeared to be primarily determined by intra-specific competition.
Neonatal cerebral hypoxia‐ischemia: involvement of FAK‐dependent pathway
Authors: Zalewska Teresa , Makarewicz Dorota , Janik Bernardetta , Ziemka‐Nałęcz Małgorzata 
Published: August 2005

AbstractFocal adhesion kinase (FAK) is a non‐receptor tyrosine kinase thought to play a major role in transducing extracellular matrix (ECM)‐derived survival signals into cells. Thus, modulation of FAK activity may affect the linkage between ECM and signaling cascade to which it is connected and may participate in a variety of pathological settings. In the present study, we investigated the effect of neonatal cerebral hypoxia‐ischemia (HI) on levels and tyrosine phosphorylation of focal adhesion kinase and the interaction of this enzyme with Src protein tyrosine kinase and adapter protein p130Cas, involved in FAK‐mediated signaling pathway. The total amount of focal adhesion kinase as well as its phosphorylated form declined substantially to about 50% of the control between 24 and 48 h after the insult. Concomitantly a decreased association of FAK with its investigated molecular partners, Src kinase and p130Cas protein has been observed. This early response to brain hypoxia‐ischemia was attenuated during prolonged recovery with almost complete return to control values at 7 days. These data are indicative of an involvement of FAK‐dependent signaling pathway in the evolution of HI‐induced neuronal degeneration.
Methionine alters Na+,K+‐ATPase activity, lipid peroxidation and nonenzymatic antioxidant defenses in rat hippocampus
Authors: Stefanello Francieli M. , Chiarani Fábria , Kurek Andréa G. , Wannmacher Clovis M.D. , Wajner Moacir , Wyse Angela T.S. 
Published: August 2005

AbstractIn the present study we investigated the effect of methionine exposure of hippocampus homogenates on Na+,K+‐ATPase activity from synaptic plasma membrane of rats. Results showed that methionine significantly decreased this enzyme activity. We also evaluated the effect of incubating glutathione (GSH) and trolox (α‐tocopherol) alone or combined with methionine on Na+,K+‐ATPase activity. The tested antioxidants per se did not alter the enzymatic activity, but prevented the inhibitory action of methionine on Na+,K+‐ATPase activity, indicating that Met inhibitory effect was probably mediated by free radical formation. Besides, we tested the in vitro effect of methionine on some parameters of oxidative stress, namely chemiluminescence, thiobarbituric acid reactive substances (TBARS), total radical‐trapping antioxidant potential (TRAP), as well as on the antioxidant enzyme activities catalase, glutathione peroxidase and superoxide dismutase in rat hippocampus. We observed that methionine significantly increased chemiluminescence and TBARS, decreased TRAP, but did not change the activity of the antioxidant enzymes. These findings suggest that reduction of Na+,K+‐ATPase activity and induction of oxidative stress may be involved in the brain damage observed in human hypermethioninemia.
Vitamin requirements for term infants: considerations for infant formulae
Authors: Powers Hilary J. 
Published: August 2005

AbstractObjectiveTo provide the informed health professional with an up to date evaluation of the current thinking regarding requirements for vitamins in infant feeds.Establishing criteria for adequacyVitamin adequacy in the neonate is currently defined in terms of circulating levels of a vitamin or of the activity of a vitamin dependent enzyme in the erythrocytes. Although these measurements have their value there is a need to develop biochemical, physiological or clinical markers of well defined specific function. For some vitamins there is a risk of deleterious effects of very high intakes: risk of toxicity needs to be taken into consideration when making recommendations for inclusion in infant formulae.Breast milk as the ‘gold standard’Breast milk concentrations of vitamins have been used as the criteria of adequate intake by neonates. This may not always be justified. Greater consideration needs to be given to differences in bioavailability of vitamins from breast milk compared with formula feeds, of the influence of season, and of stage of lactation, on the stated composition.Experimental approachesAnimal studies have provided limited information regarding effects of different levels of intakes on current status indices in the neonatal period. There are few reports of randomized controlled studies into the effects of different levels of vitamins and these rely heavily on biochemical criteria of adequacy.Recent developmentsThe inclusion of β-carotene into formula feeds for premature babies is an issue of current interest. What is the justification for this? Are there potential benefits for the term infant? Riboflavin deficiency in the period around weaning may affect the normal structural and functional development of the gastrointestinal tract; some of these effects may be permanent.Research to be doneA greater understanding of the absorption and metabolism of vitamins during infancy is required in order to help establish dietary requirements. The relative bioavailability of vitamins in human milk and formulae needs to be investigated. Criteria for vitamin adequacy should be extended to include measures of function. Information regarding the conversion factor from tryptophan to niacin in infancy would allow us to set niacin requirements with greater confidence. There is a particular lack of information about concentrations of biotin and pantothenic acid in breast milk and the relative biochemical status of infants receiving breast milk and formulae. Benefits of including β-carotene into infant formulae need to be evaluated. The role of individual micronutrients in the structural and functional development of the gastrointestinal tract should be explored.
Health effects of breast feeding for mothers: a critical review
Authors: Heinig M. Jane , Dewey Kathryn G. 
Published: August 2005

AbstractLactation results in a number of physiological adaptations which exert direct effects on maternal health, some of which may confer both short and long term advantages for breast feeding mothers. Breast feeding in the early postpartum period promotes a more rapid return of the uterus to its prepregnant state through the actions of oxytocin. Breast feeding may also lead to a more rapid return to prepregnancy weight. Among studies that had good data on duration and intensity of lactation, the majority show a significant association between lactation and weight loss. However, there is no evidence that lactation prevents obesity. Lactation also affects glucose and lipid metabolism. The long term effects of these adaptations are unknown but may have implications for preventing subsequent development of diabetes and heart disease. Lactation delays the return of ovulation and significantly reduces fertility during the period of lactational amenorrhoea. This process is linked with feeding patterns and may therefore be affected by practices such as scheduled feedings and the timing of introduction of complementary foods. While the evidence from epidemiologic studies is mixed, several large studies have shown that extended lactation is associated with reduced risk of premenopausal breast, ovarian and endometrial cancers. Although bone mineralization declines during lactation, repletion takes place after weaning. As a result, breast feeding does not appear to cause long term depletion of bone nor does it increase risk of osteoporosis. Many of the physiological effects of lactation are dependent on the stimulation of the hypothalamic-pituitary axis and milk removal and thus may vary with infant feeding practices. Well controlled studies are needed that include detailed information regarding infant feeding practices in addition to the total duration of any breast feeding. Future feeding recommendations should reflect careful consideration of how such practices affect both infant and maternal health.
Diet and haemostatic processes
Authors: Vorster Hester H. , Cummings John H. , Jerling Johann C. 
Published: August 2005

AbstractDiet plays an important role in the primary and secondary prevention of cardiovascular disease. The growing perception that abnormal haemostatic processes of coagulation, platelet aggregation and fibrinolysis contribute to cardiovascular disease aetiology motivated this review on the relationships of diet, specific foods and nutrients with haemostatic function. Functional endpoints that reflect the function and status of some of these processes and which can be measured in dietary trials are identified. The effects of energy intake and expenditure, alcohol, total fat and specific fatty acids, non-starch polysaccharides (dietary fibre), antioxidant nutrients and some foods on a variety of haemostatic markers are reviewed. The results indicate that the prudent low-fat, high-fibre diet and maintenance of ideal body weight recommended to protect against and treat hyperlipidaemia and coronary heart disease will also benefit haemostatic profiles. It is concluded that more research on specific effects is needed for improved recommendations on a population level for prevention of cardiovascular disease.