bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of transcription factors during oligodendroglial development
Authors: Wegner Michael 
Published: August 2002

AbstractTranscription factors coordinate the orderly changes of gene expression that underlie all developmental processes including those of oligodendrocytes. In comparison to other systems, relatively little is known about the role of transcription factors during oligodendrocyte development. However, recent years have seen the identification of oligodendroglial transcription factors that, not surprisingly, belong to the same gene families that are also important in other tissues or cell lineages. Some transcription factors such as the bHLH (basic helix‐loop‐helix) proteins Olig‐1 and Olig‐2 or the high‐mobility‐group protein Sox10 are expressed already early during development of the oligodendrocyte lineage, whereas expression of other transcription factors such as the homeodomain protein Gtx/Nkx6.2 only start at the time of terminal differentiation. Once turned on, expression of these proteins can either be permanent as in the above‐mentioned cases or transient as exemplified by the POU domain proteins Tst‐1/Oct6/SCIP, Brn‐1 and Brn‐2. Analyses of these transcription factors has already led to the identification of important principles such as functional redundancy between co‐expressed proteins, unexpected divergence in the transcription factor repertoire of oligodendrocytes and Schwann cells, and equally unsuspected similarities in transcription factor usage between oligodendrocytes and neurons. Although so far only a small percentage of oligodendroglial transcription factors has been identified, these are excellent candidates for regulators of cell type specification, lineage progression, and terminal differentiation. Microsc. Res. Tech. 52:746–752, 2001. © 2001 Wiley‐Liss, Inc.
Immunopathogenesis of delayed‐type hypersensitivity
Authors: Kobayashi Kazuo , Kaneda Kenji , Kasama Tsuyoshi 
Published: August 2002

AbstractCell‐mediated immunity is defined as a beneficial host response characterized by an expanded population of specific T cells, which, in the presence of antigens, produce cytokines locally. The activation and recruitment of cells into an area of inflammation is a crucial step in the development of DTH responses. DTH is immunologically a process similar to cell‐mediated immunity, involving T cells and cytokines. CD4 T helper (Th) 1 cells, differentiated from naive Th cells by IL‐12 and IL‐18 produced from macrophages, play a regulatory role in the expression of DTH and activation of macrophages via interferon γ generated by Th1 and natural killer cells. Macrophages accumulate at the site of DTH and become activated through the CD4 Th1 cell‐cytokine‐macrophage axis. However, DTH leads to pathologic responses, such as granulomatous inflammation, calcification, caseation necrosis, and cavity formation. Granulomas usually form as a result of the persistence of a nondegradable product or as the result of DTH responses. DTH is also required for host defense against etiologic agents, such as Mycobacterium tuberculosis. The expression of cell‐mediated immunity/DTH is a double‐edged sword that may contribute to both clearance of the etiologic agent and tissue damage. Microsc. Res. Tech. 53:241–245, 2001. © 2001 Wiley‐Liss, Inc.
Role of dendritic cells and Th2 lymphocytes in asthma: Lessons from eosinophilic airway inflammation in the mouse
Authors: Van Rijt Leonie S. , Lambrecht Bart N. 
Published: August 2002

AbstractAsthma is a chronic disorder of the airways characterized by variable airway narrowing, mucus hypersecretion, and infiltration of the airway wall with eosinophils. It is now believed that asthma is controlled by Th2 lymphocytes producing cytokines such as IL‐4, IL‐5, IL‐9, and IL‐13. Animal models of eosinophilic airway inflammation and airway hyperreactivity have been developed to study the contribution of cells or mediators in the pathogenesis of asthma. In this review, we discuss the role of antigen presenting cells, CD4+ and CD8+ T lymphocytes, B lymphocytes, NK cells, and mast cells in the induction and maintenance of eosinophilic airway inflammation, mucus hypersecretion, and airway hyperreactivity. Microsc. Res. Tech. 53:256–272, 2001. © 2001 Wiley‐Liss, Inc.
Energy expenditure and testosterone in free‐living male yellow‐pine chipmunks
Authors: Place Ned J. , Veloso Claudio , Visser G.H. , Kenagy G.J. 
Published: August 2002

AbstractThe onset of mating in yellow‐pine chipmunks (Tamias amoenus) follows emergence from a prolonged period of energy conservation during hibernation. Energy expenditures are greatly accelerated to meet the demands of the reproductive season. When emerging from hibernation, typical male chipmunks (breeders) have enlarged testes and a high level of plasma testosterone (T). However, certain males that do not participate in reproduction (nonbreeders) maintain small testes and low plasma T levels and emerge several weeks later than the breeders. The timing of the terminal arousal from hibernation and onset of mating are associated with increased plasma T levels. Experimental elevation of T levels in T. amoenus outside the mating season has been associated with a decrease in body mass, further suggesting an effect of T on energy balance. To test this hypothesis, we measured daily energy expenditure (DEE) in free‐living, nonbreeding male chipmunks in the presence and absence of a T‐implant. We also measured DEE in breeding males when endogenous T levels were high. DEE of the nonbreeders was not affected by our manipulation of plasma T, and the DEE of breeding males did not differ from that of nonbreeders. We conclude that energy expenditure on a daily basis in male yellow‐pine chipmunks is not influenced by levels of T. However, on a seasonal basis, the earlier emergence from hibernation by breeding males, which appears to be influenced by T, represents an overall seasonal energy expenditure that exceeds that of nonbreeding males. J. Exp. Zool. 292:460–467, 2002. © 2002 Wiley‐Liss, Inc.
Ammonia excretion and urea handling by fish gills: present understanding and future research challenges
Authors: Wilkie Michael Patrick 
Published: August 2002

AbstractIn fresh water fishes, ammonia is excreted across the branchial epithelium via passive NH3 diffusion. This NH3 is subsequently trapped as NH in an acidic unstirred boundary layer lying next to the gill, which maintains the blood‐to‐gill water NH3 partial pressure gradient. Whole animal, in situ, ultrastructural and molecular approaches suggest that boundary layer acidification results from the hydration of CO2 in the expired gill water, and to a lesser extent H+ excretion mediated by apical H+‐ATPases. Boundary layer acidification is insignificant in highly buffered sea water, where ammonia excretion proceeds via NH3 diffusion, as well as passive NH diffusion due to the greater ionic permeability of marine fish gills. Although Na+/H+ exchangers (NHE) have been isolated in marine fish gills, possible Na+/NH exchange via these proteins awaits evaluation using modern electrophysiological and molecular techniques. Although urea excretion (JUrea) was thought to be via passive diffusion, it is now clear that branchial urea handling requires specialized urea transporters. Four urea transporters have been cloned in fishes, including the shark kidney urea transporter (shUT), which is a facilitated urea transporter similar to the mammalian renal UT‐A2 transporter. Another urea transporter, characterized but not yet cloned, is the basolateral, Na+ dependent urea antiporter of the dogfish gill, which is essential for urea retention in ureosmotic elasmobranchs. In ureotelic teleosts such as the Lake Magadi tilapia and the gulf toadfish, the cloned mtUT and tUT are facilitated urea transporters involved in JUrea. A basolateral urea transporter recently cloned from the gill of the Japanese eel (eUT) may actually be important for urea retention during salt water acclimation. A multi‐faceted approach, incorporating whole animal, histological, biochemical, pharmacological, and molecular techniques is required to learn more about the location, mechanism of action, and functional significance of urea transporters in fishes. © 2002 Wiley‐Liss, Inc.
Mannan‐degrading enzymes purified from the crop of the brown garden snail Helix aspersa Müller (Gastropoda Pulmonata)
Authors: Charrier Maryvonne , Rouland Corinne 
Published: August 2002

AbstractTwo mannan‐degrading enzymes were purified from the crop of the terrestrial snail Helix aspersa Müller. The crude extracts were taken from dormant (for 4 months) snails. The enzymes were a βD‐mannanase of 37.4 ± 0.3 kDa (EC 3.2.1.78) and a βD‐mannosidase of 77.8 ± 1.9 kDa (EC 3.2.1.25). Both enzymes degraded insoluble mannan, releasing either mannose only (β‐mannosidase) or oligosaccharides, possibly mannotriose and mannopentaose (β‐mannanase). The β‐mannanase had a typical endo‐activity pattern, while the β‐mannosidase was an exoenzyme. The incubation of both enzymes with mannan increased the catalysis by 83%. The best synergy was found with 75% mannosidase combined with 25% mannanase. The β‐mannanase also hydrolysed β‐linked heteromannans and its affinity for different galactomannans was studied. The Km values, varying from 2.89 ± 0.47 mg × ml–1 to 0.26 ± 0.01 mg × ml–1, revealed the inhibitory effect of the αD‐galactosyl residues released. The β‐mannosidase was acidic (optimum pH = 3.3) and heat‐sensitive (50% residual activity at 42°C after 5 min of pre‐incubation), while the β‐mannanase remained stable until 48.5°C (50% residual activity) and over a pH range of 4.3–7.5. The properties of these mannanolytic enzymes are discussed in this paper compared with those purified in other gastropods and in a bacterium, Enterococcus casseliflavus, a quite similar strain previously isolated from this snail intestine. The occurrence of thermostable enzymes in H. aspersa digestive tract could be a zootechnic parameter of great importance for snail farming. J. Exp. Zool. 290:125–135, 2001. © 2001 Wiley‐Liss, Inc.
Varieties of modules: Kinds, levels, origins, and behaviors
Authors: Winther Rasmus G. 
Published: August 2002

AbstractThis article began as a review of a conference, organized by Gerhard Schlosser, entitled “Modularity in Development and Evolution.” The conference was held at, and sponsored by, the Hanse Wissenschaftskolleg in Delmenhorst, Germany in May, 2000. The article subsequently metamorphosed into a literature and concept review as well as an analysis of the differences in current perspectives on modularity. Consequently, I refer to general aspects of the conference but do not review particular presentations. I divide modules into three kinds: structural, developmental, and physiological. Every module fulfills none, one, or multiple functional roles. Two further orthogonal distinctions are important in this context: module‐kinds versus module‐variants‐of‐a‐kind and reproducer versus nonreproducer modules. I review criteria for individuation of modules and mechanisms for the phylogenetic origin of modularity. I discuss conceptual and methodological differences between developmental and evolutionary biologists, in particular the difference between integration and competition perspectives on individualization and modular behavior. The variety in views regarding modularity presents challenges that require resolution in order to attain a comprehensive, rather than a piecemeal and fragmentary, evolutionary developmental biology. J. Exp. Zool. (Mol. Dev. Evol.) 291:116–129, 2001. © 2001 Wiley‐Liss, Inc.
Persistence of oviposition rhythm in individuals of Drosophila melanogaster reared in an aperiodic environment for several hundred generations
Authors: Sheeba V. , Chandrashekaran M.K. , Joshi Amitabh , Sharma Vijay Kumar 
Published: August 2002

AbstractThe oviposition rhythm of individual flies of Drosophila melanogaster from a population maintained in an aperiodic environment (with light, temperature, humidity, and other factors which could provide time cues, kept constant) for several hundred generations was assayed in constant light (LL), in light/dark (LD 12:12 hr) cycle, and in constant darkness (DD). More than 50% of the flies assayed exhibited rhythmicity in oviposition in all three light regimes. The results indicate that the phenomenon of egg laying is rhythmic in individual D. melanogaster females and is controlled by an endogenous time keeping mechanism. The persistence of the oviposition rhythm in a large proportion of individuals in the population after several hundred generations of rearing in a constant environment strengthens the view that possessing biological clocks may confer some intrinsic fitness advantage even to organisms living in aperiodic environments. J. Exp. Zool. 290:541–549, 2001. © 2001 Wiley‐Liss, Inc.
Theory of the growth and evolution of feather shape
Authors: Prum Richard O. , Williamson Scott 
Published: August 2002

AbstractWe present the first explicit theory of the growth of feather shape, defined as the outline of a pennaceous feather vane. Based on a reanalysis of data from the literature, we propose that the absolute growth rate of the barbs and rachis ridges, not the vertical growth rate, is uniform throughout the follicle. The growth of feathers is simulated with a mathematical model based on six growth parameters: (1) absolute barb and rachis ridge growth rate, (2) angle of helical growth of barb ridges, (3) initial barb ridge number, (4) new barb ridge addition rate, (5) barb ridge diameter, and (6) the angle of barb ramus expansion following emergence from the sheath. The model simulates growth by cell division in the follicle collar and, except for the sixth parameter, does not account for growth by differentiation in cell size and shape during later keratinization. The model can simulate a diversity of feather shapes that correspond closely in shape to real feathers, including various contour feathers, asymmetrical feathers, and even emarginate primaries. Simulations of feather growth under different parameter values demonstrate that each parameter can have substantial, independent effects on feather shape. Many parameters also have complex and redundant effects on feather shape through their influence on the diameter of the follicle, the barb ridge fusion rate, and the internodal distance. Simulated isochrones—the loci, or sets, of feather cells of the same age—have the same oblique chevron‐shaped position in the mature feather as fault bars, which are isochronic defects in the barbules created by a disruptions during development. Accurate simulation of fault bar shape and position confirms the uniform absolute growth rate hypothesis and the general realism of the model. The theory defines a six‐parameter feather morphospace, and provides many predictions about the developmental determination of feather shape that can be tested with detailed observations and experiments on developing feathers. This theory also provides testable predictions about the changes in developmental mechanisms required to evolve different feather shapes to accomplish various functions. J. Exp. Zool. (Mol. Dev. Evol.) 291:30–57, 2001. © 2001 Wiley‐Liss, Inc.
Tiled partial cubes
Authors: Brešar Boštjan , Imrich Wilfried , Klavžar Sandi , Mulder Henry Martyn , Škrekovski Riste 
Published: August 2002

AbstractIn the quest to better understand the connection between median graphs, triangle‐free graphs and partial cubes, a hierarchy of subclasses of partial cubes has been introduced. In this article, we study the role of tiled partial cubes in this scheme. For instance, we prove that almost‐median graphs are tiled and that tiled partial cubes are semi‐median. We also describe median graphs as tiled partial cubes without convex Q and extend an inequality for median graphs to a larger subclass of partial cubes. © 2002 Wiley Periodicals, Inc. J Graph Theory 40: 91–103, 2002
Innovative and important, yes, but also instrumental and incomplete: the treatment of redistribution in the new ‘New Poverty Agenda’
Authors: Maxwell Simon 
Published: August 2002

AbstractThe current narrative on poverty reduction, summarized in WDR 2000/1, rehabilitates distribution as a central topic on the development agenda. WDR argues (i) that redistribution matters for instrumental reasons, as a route to faster growth and faster poverty reduction; (ii) that changes to income distribution result from complex changes in sectoral, geographical and individual performance; and (iii) that better distribution can be achieved in a win‐win fashion, without undermining incentives or forcing a choice between equity and efficiency. The argument can be extended: (i) the case for redistribution is not simply instrumental, but can be rooted in a discourse about social inclusion and rights; (ii) observed changes are strongly associated with liberalization policies, and with changes to social norms; and (iii) governments can do more than the Bank suggests to achieve greater equality. A commitment to redistribution should be enshrined in a new international development target: a ceiling on Gini coefficients of 0.45. Copyright © 2001 John Wiley & Sons, Ltd.
Neurostimulation systems for deep brain stimulation: In vitro evaluation of magnetic resonance imaging–related heating at 1.5 tesla
Authors: Rezai Ali R. , Finelli Daniel , Nyenhuis John A. , Hrdlicka Greg , Tkach Jean , Sharan Ashwini , Rugieri Paul , Stypulkowski Paul H. , Shellock Frank G. 
Published: August 2002

AbstractPurposeTo assess magnetic resonance imaging (MRI)‐related heating for a neurostimulation system (Activa® Tremor Control System, Medtronic, Minneapolis, MN) used for chronic deep brain stimulation (DBS).Materials and MethodsDifferent configurations were evaluated for bilateral neurostimulators (Soletra® Model 7426), extensions, and leads to assess worst‐case and clinically relevant positioning scenarios. In vitro testing was performed using a 1.5‐T/64‐MHz MR system and a gel‐filled phantom designed to approximate the head and upper torso of a human subject. MRI was conducted using the transmit/receive body and transmit/receive head radio frequency (RF) coils. Various levels of RF energy were applied with the transmit/receive body (whole‐body averaged specific absorption rate (SAR); range, 0.98–3.90 W/kg) and transmit/receive head (whole‐body averaged SAR; range, 0.07–0.24 W/kg) coils. A fluoroptic thermometry system was used to record temperatures at multiple locations before (1 minute) and during (15 minutes) MRI.ResultsUsing the body RF coil, the highest temperature changes ranged from 2.5°–25.3° C. Using the head RF coil, the highest temperature changes ranged from 2.3°–7.1° C.Thus, these findings indicated that substantial heating occurs under certain conditions, while others produce relatively minor, physiologically inconsequential temperature increases.ConclusionThe temperature increases were dependent on the type of RF coil, level of SAR used, and how the lead wires were positioned. Notably, the use of clinically relevant positioning techniques for the neurostimulation system and low SARs commonly used for imaging the brain generated little heating. Based on this information, MR safety guidelines are provided. These observations are restricted to the tested neurostimulation system. J. Magn. Reson. Imaging 2002;15:241–250. © 2002 Wiley‐Liss, Inc.
Modulation of cerebral blood oxygenation by indomethacin: MRI at rest and functional brain activation
Authors: Bruhn Harald , Fransson Peter , Frahm Jens 
Published: August 2002

AbstractThe modulation of blood oxygenation level‐dependent (BOLD) cerebral MRI contrast by the vasoconstrictive drug indomethacin (i.v. 0.2 mg/kg b.w.) was investigated in 10 healthy young adults without and with functional challenge (repetitive and sustained visual activation). For comparison, isotonic saline (placebo, 20 mL) and acetylsalicylate (i.v. 500 mg) were investigated as well, each in separate sessions using identical protocols. After indomethacin, dynamic T2*‐weighted echo‐planar MRI at 2.0 T revealed a rapid decrease in MRI signal intensity by 2.1%–2.6% in different gray matter regions (P ≤ 0.001 compared to placebo), which was not observed for acetylsalicylate and the placebo condition. Regional signal differences were not significant within gray matter, but all gray matter regions differed significantly from the signal decrease of only 1.2% ± 0.7% observed in white matter (P = 0.001). For the experimental parameters used, a 1% MRI signal decrease in response to indomethacin was estimated to correlate with a decrease of the cerebral blood flow by about 12 ml/100 g/minute, and an increase of the oxygen extraction fraction by about 15%. Responses to visual activation were not affected by saline or acetylsalicylate, and yielded 5.0%–5.5% BOLD MRI signal increases both before and after drug application. In contrast, indomethacin reduced the initial response strength to 82%–85% of that obtained without the drug. The steady‐state response during sustained activation reached only 47% of the corresponding pre‐drug level (P < 0.01). During repetitive activation the BOLD contrast was reduced to 66% of that observed for control conditions (P < 0.001). In conclusion, indomethacin attenuates the vasodilatory force at functional brain activation, indicating different mechanisms governing neurovascular coupling. J. Magn. Reson. Imaging 2001;13:325–334. © 2001 Wiley‐Liss, Inc.
A multi‐scale method for automatic correction of intensity non‐uniformity in MR images
Authors: Han Chao , Hatsukami Thomas S. , Yuan Chun 
Published: August 2002

AbstractIn this paper, a novel multi‐scale method for coil sensitivity profile correction is presented based on wavelet transform. A magnetic resonance (MR) image can be decomposed into two spaces by the wavelet transform: approximate space and residual space. The approximate templates in approximate space can be thought of as multi‐scale sensitivity profiles of the surface coil for coil correction. When we choose a suitable filter for decomposition, one of the sensitivity profiles should be optimal among the multi‐scale sensitivity profiles. The optimal sensitivity profile can be chosen automatically by an analysis of the contents of the two spaces. The multi‐scale method does not rely on any data other than the image generated by the MR scanner. The experiment showed promising results based on one‐dimensional simulation and images of phantom and human images. J. Magn. Reson. Imaging 2001;13:428–436. © 2001 Wiley‐Liss, Inc.
Examination of intra‐gastrointestinal tract signal elimination in MRCP: Combined use of T1‐shortening positive contrast agent and single‐shot fast inversion recovery
Authors: Kato Joji , Kawamura Yoshihiko , Watanabe Tsuneo , Okada Susumu , Cho Keiichi , Ishihara Makiko 
Published: August 2002

AbstractTo examine the effects of removing the gastrointestinal signal in MR cholangiopancreatography (MRCP), investigations were carried out on the combined use of T1‐shortening intestine‐positive contrast medium, FerriSeltz with ferric ammonium citrate as the main component, and high‐speed imaging using single‐shot fast inversion recovery (SSFIR). The contrast effect was significantly elevated to 10.2 ± 1.6 after administration, compared with 5.9 ± 2.4 before administration (P < 0.001). The enhancement effect was also significantly elevated to 13.2 ± 3.0 after administration, compared with 4.9 ± 3.1 before administration (P < 0.001). These results were obtained because the null point of FerriSeltz aqueous solution (5.97 mmol/L) was in the range of approximately 180 msec. With the present method, adequate suppression of the signal intensity of the digestive tract was obtained relatively easily with MRCP, and the technique was found to be effective. J. Magn. Reson. Imaging 2001;13:738–743. © 2001 Wiley‐Liss, Inc.