bluuebunny/crossref_metadata_2025_split huggingface dataset:
An experimental study on the ripple–dune transition
Authors: Robert André , Uhlman William 
Published: August 2002

AbstractFlume experiments were conducted on different bed stages across the ripple–dune transition. As flow velocity increases, an initially flat bed surface (made of fairly uniform sandy material) is gradually transformed into a two‐dimensional rippled bed. With further increase in velocity, two‐dimensional ripples are replaced by irregular, linguoid ripples. As the average velocity necessary for the ripple–dune transition to occur is imposed on the bed surface, these non‐equilibrium linguoid ripples are further transformed into larger, two‐dimensional dunes. For each of these stages across the transition, a concrete mould of the bed was created and the flow structure above each fixed bed surface investigated. An acoustic Doppler velocimeter was used to study the flow characteristics above each bed surface. Detailed profiles were used along a transect located in the middle of the channel. Results are presented in the form of spatially averaged profiles of various flow characteristics and of contour maps of flow fields (section view). They clearly illustrate some important distinctions in the flow structure above the different bedform types associated with different stages during the transition. Turbulence intensity and Reynolds stresses gradually increase throughout the transition. Two‐dimensional ripples present a fairly uniform spatial distribution of turbulent flow characteristics above the bed. Linguoid ripples induce three‐dimensional turbulence structure at greater heights above the bed surface and turbulence intensity tends to increase steadily with height above bed surface in the wake region. A very significant increase in turbulence intensity and momentum exchange occurs during the transition from linguoid ripples to dunes. The turbulent flow field properties above dunes are highly dependent on the position along and above the bed surface and these fields present a very high degree of spatial variability (when compared with the rippled beds). Further investigations under natural conditions emphasizing sediment transport mechanisms and rates during the transition should represent the next step of analysis, together with an emphasis on quadrant analysis. Copyright © 2001 John Wiley & Sons, Ltd.
Embryonic expression and regulation of the large zinc finger protein KRC
Authors: Hicar Mark D. , Robinson Michael L. , Wu Lai‐Chu 
Published: August 2002

AbstractSummary: KRC fusion proteins bind to the κB enhancer motif and to the signal sequences of V(D)J recombination. Here we have characterized endogenous KRC in mouse embryos and lymphoma cell lines. Starting from midgestation, neuronal‐ and lymphoid‐restricted expression of KRC was observed from the dorsal root ganglia, trigeminal ganglion, thymus, and cerebral cortex. Several B‐cell lines produced an alternatively spliced KRC transcript of 4.5 kb and a 115‐kDa DNA‐binding protein isoform. Additionally, that KRC transcript was induced by lipopolysaccharide, a potent activator of cells in immunity and inflammation. In genetic‐engineered B cells stably transfected with inducible expression vectors for the recombination activating genes RAG1, RAG2, or both, the avidity of KRC to DNA was markedly decreased when RAG1 and RAG2 were overexpressed. We hypothesize that KRC may function in developing thymocytes and neurons, where its role might be transcription regulation or DNA recombination. genesis 33:8–20, 2002. © 2002 Wiley‐Liss, Inc.
Hypomorphic phenotype in mice with pituitary‐specific knockout of steroidogenic factor 1
Authors: Zhao Liping , Bakke Marit , Krimkevich Yelena , Cushman Lisa J. , Parlow A. F. , Camper Sally A. , Parker Keith L. 
Published: August 2002

AbstractSummary: The bacteriophage Cre recombinase provides a powerful approach for tissue‐specific gene inactivation. Using a Cre transgene driven by the common alpha subunit of glycoprotein hormones (αGSU‐Cre), we have previously inactivated steroidogenic factor 1 (SF‐1) in the anterior pituitary, causing hypogonadotropic hypogonadism with sexual infantilism, sterility, and severe gonadal hypoplasia. We now explore the molecular mechanisms underlying a hypomorphic gonadal phenotype in mice carrying two floxed SF‐1 alleles (F/F) relative to mice carrying one recombined and one floxed allele (F/R). Because their Cre‐mediated disruption of the locus encoding SF‐1 was less efficient, αGSU‐Cre, F/F mice retained some gonadotropin‐expressing cells in the anterior pituitary, thereby stimulating some gonadal function. This novel in vivo model for exploring the effects of differing levels of gonadotropins on gonadal development highlights the need for careful genotype‐phenotype comparisons in studies using Cre recombinase to produce tissue‐specific knockouts. genesis 30:65–69, 2001. © 2001 Wiley‐Liss, Inc.
Similar myogenic functions for myogenin and MRF4 but not MyoD in differentiated murine embryonic stem cells
Authors: Sumariwalla Veera M. , Klein William H. 
Published: August 2002

AbstractSummary: The emergence of four genes encoding myogenic bHLH transcription factors in the stem vertebrate is a unique feature of vertebrate evolution that led to the acquisition of new target genes and novel regulatory circuits for skeletal muscle formation. One unresolved question is the extent to which each factor has evolved specialized functions for regulating muscle gene transcription. We have developed a system using differentiated myogenin (‐/‐) embryonic stem (ES) cells to determine whether other myogenic factors can replace myogenin's function in muscle differentiation. Previously, we showed that constitutively expressed myogenin restores myofiber formation in differentiated myogenin (‐/‐) ES cells, but constitutively expressed MyoD does not. Here, we confirm the distinction between myogenin and MyoD using another expression vector and show that constitutively expressed MRF4 leads to myofiber formation in myogenin's absence. Our analysis reveals a correlation between the levels of myogenin plus MRF4 and the extent of myofiber formation, suggesting a synergy between these factors. The results indicate that unlike MyoD, MRF4 plays a role similar to myogenin in skeletal muscle differentiation. genesis 30:239–249, 2001. © 2001 Wiley‐Liss, Inc.
Genome‐wide linkage analysis of blood pressure in Mexican Americans
Authors: Atwood Larry D. , Samollow Paul B. , Hixson James E. , Stern Michael P. , MacCluer Jean W. 
Published: August 2002

AbstractThe genetic mechanisms that control variation in blood pressure level are largely unknown. One of the first steps in understanding those mechanisms is the localization of the genes that have a significant effect on blood pressure. We performed genome scans of systolic (SBP) and diastolic blood pressure (DBP) on a population‐based sample of families in the San Antonio Family Heart Study. A likelihood‐based Mendelian model incorporating genotype‐specific effects of sex, age, age2, BMI, and blood pressure (SBP or DBP, as appropriate) as covariates was used to perform two‐point lodscore (Z) linkage on 399 polymorphic markers. Results showed that the genotype‐specific covariate effects were highly significant for both SBP and DBP. Linkage results showed that a quantitative trait locus (QTL) influencing DBP was significantly linked to D2S1790 (Z = 3.92, θ = 0.00) and showed suggestive linkage to D8S373 (Z = 1.92, θ = 0.00). A QTL influencing SBP showed suggestive linkage to D21S1440 (Z = 2.82, θ = 0.00) and D18S844 (Z = 2.09, θ = 0.11). Without the genotype‐specific effects in the model, the linkage to D2S1790 was not even suggestive (Z = 1.33, θ = 0.09); thus genotype‐specific modeling was crucial in detecting this linkage. A comparison with linkage studies based in other populations showed that the significant linkage to D2S1790 has been replicated at the same marker in the Quebec Family Study. The replicated significant linkage at D2S1790 may begin to establish the locations of the genes that significantly affect blood pressure across several human ethnic groups. Genet. Epidemiol. 20:373–382, 2001. © 2001 Wiley‐Liss, Inc.
Stratigraphy and palaeoenvironmental development of Quaternary coarse clastic beach deposits at Plage de Mezpeurleuch, Brittany (France)
Authors: Haslett Simon K. , Curr Richard H. F. 
Published: August 2002

AbstractQuaternary deposits are described from well‐exposed sections in cliffs at Plage de Mezpeurleuch, Finistère, Brittany (France). The general lithostratigraphic sequence comprises Holocene perched dune sand, calcrete and palaeosol overlying Weichselian head and coarse clastic palaeobeach units attributed to the last interglacial (Eemian–isotope substage 5e). A lower and an upper palaeobeach, separated by a thin head deposit, are reported resting on an irregular palaeorock platform eroded in Hercynian granite. From a comparison with modern coastal environments a palaeoenvironmental interpretation of the palaeobeach deposits is made. Erosionally bounded facies of the lower palaeobeach, are considered to be a transgressive sequence preserved by drowning associated with a rapid rise in relative sea‐level. Its subsequent abandonment is attributed to a relative sea‐level fall, which allowed a terrestrial environment to develop briefly. Facies of the upper palaeobeach however indicate a prograding shoreline developed during a prolonged period of relatively stable sea‐level. These sea‐level observations are in good agreement with other evidence for a brief widespread intra‐Eemian cold event. Copyright © 2001 John Wiley & Sons, Ltd.
Mechanisms of apoptosis induced by purine nucleosides in astrocytes
Authors: Di Iorio Patrizia , Kleywegt Sonya , Ciccarelli Renata , Traversa Ugo , Andrew Craig M. , Crocker Candice E. , Werstiuk Eva S. , Rathbone Michel P. 
Published: August 2002

AbstractAstrocytes release adenine‐based and guanine‐based purines under physiological and, particularly, pathological conditions. Thus, the aim of this study was to determine if adenosine induced apoptosis in cultured rat astrocytes. Further, if guanosine, which increases the extracellular concentration of adenosine, also induced apoptosis determined using the TUNEL and Annexin V assays. Adenosine induced apoptosis in a concentration‐dependent manner up to 100 μM. Inosine, hypoxanthine, guanine, and guanosine did not. Guanosine or adenosine (100 μM) added to the culture medium was metabolized, with 35% or 15%, respectively, remaining after 2–3 h. Guanosine evoked the extracellular accumulation of adenosine, and particularly of adenine‐based nucleotides. Cotreatment with EHNA and guanosine increased the extracellular accumulation of adenosine and induced apoptosis. Inhibition of the nucleoside transporters using NBTI (100 μM) or propentophylline (100 μM) significantly decreased but did not abolish the apoptosis induced by guanosine + EHNA or adenosine + EHNA, respectively. Apoptosis produced by either guanosine + EHNA or adenosine + EHNA was unaffected by A1 or A2 adenosine receptor antagonists, but was significantly reduced by MRS 1523, a selective A3 adenosine receptor antagonist. Adenosine + EHNA, not guanosine + EHNA, significantly increased the intracellular concentration of S‐adenosyl‐L‐homocysteine (SAH) and greatly reduced the ratio of S‐adenosyl‐L‐methioine to SAH, which is associated with apoptosis. These data demonstrate that adenosine mediates apoptosis of astrocytes both, via activation of A3 adenosine receptors and by modulating SAH hydrolase activity. Guanosine induces apoptosis by accumulating extracellular adenosine, which then acts solely via A3 adenosine receptors. GLIA 38:179–190, 2002. © 2002 Wiley‐Liss, Inc.
Increased syndecan expression by pleiotrophin and FGF receptor‐expressing astrocytes in injured brain tissue
Authors: Iseki Ken , Hagino Seita , Mori Tetsuji , Zhang Yuxiang , Yokoya Sachihiko , Takaki Hiromi , Tase Choichiro , Murakawa Masahiro , Wanaka Akio 
Published: August 2002

AbstractSyndecan‐1, ‐2, ‐3, and ‐4 are heparan sulfate proteoglycans that are differentially expressed during development and wound repair. To determine whether syndecans are also involved in brain injury, we examined the expression of syndecan core proteins genes in cryo‐injured mouse brain, using in situ hybridization. All syndecan mRNA transcripts were similarly expressed in the region surrounding the necrotic tissue, exhibiting peak levels at day 7 after injury. Comparison with cellular markers showed that reactive astrocytes were the primary source of syndecans. Syndecans serve as co‐receptors for fibroblast growth factor (FGF) and as a reservoir for another heparin‐binding growth factor, pleiotrophin (PTN, or heparin‐binding growth‐associated molecule. In our model, FGF receptor1 (FGFR1) and PTN mRNA levels were upregulated in reactive astrocytes. The distribution patterns of FGFR1 and PTN overlapped considerably with those of syndecan‐1 and ‐3 mRNAs, respectively. These results suggest that syndecans are expressed primarily in reactive astrocytes, and may provide a supportive environment for regenerating axons in concert with heparin‐binding growth factors (e.g., FGF and PTN) in the injured brain. GLIA 39:1–9, 2002. © 2002 Wiley‐Liss, Inc.
Basic principles of immunological surveillance of the normal central nervous system
Authors: Hickey William F. 
Published: August 2002

AbstractUnlike most bodily organs, the central nervous system (CNS) exists behind a blood–tissue barrier designed to minimize the passage of cells and macromolecules into the neural parenchyma. Yet, the CNS is routinely and effectively surveyed by the immune system. This review examines the mechanisms and participants in this immunological surveillance mechanism. The nature of the healthy blood–brain barrier, factors modifying it, and its central position in determining the number and nature of leukocytes permitted to enter, are considered. In addition the role in surveillance played by lymphatic drainage, migrating T and B lymphocytes, and elements of the monocyte/macrophage/microglia family are considered. While all these participants are known to be important in responding to a CNS antigen and/or establishing a site of inflammation in the nervous system, they also are major elements in maintaining the homeostasis of the CNS and permitting the necessary immunological surveillance of that organ. GLIA 36:118–124, 2001. © 2001 Wiley‐Liss, Inc.
Depressive symptoms among poststroke patients in Japan: frequency distribution and factor structure of the GDS
Authors: Schreiner Andrea S. , Morimoto Tomoko , Asano Hitoshi 
Published: August 2002

AbstractObjectiveThe present study examined the nature, prevalence, and covariates of depressive symptoms among home‐dwelling poststroke patients in Japan using the Geriatric Depression Scale Short Form (GDS‐1). Poststroke results were compared with those of elderly with affective disorders and with those of healthy nonstroke elderly.MethodsPoststroke patients (n = 101) who did not also have a diagnosis of Alzheimer's dementia, were identified from patient records at seven randomly selected hospitals with outpatient rehabilitation clinics in a metropolitan area in western Japan and invited to participate in the study. All instruments were interview‐administered.ResultsGDS scores did not correlate with age, sex, education, functional dependence, aphasia, paralysis or presence of other chronic illnesses. However, GDS scores did correlate significantly with self‐rated general health and poststroke duration. Compared with the frequency distribution in a psychiatric sample, poststroke patients had higher positive affect and lower depressed mood but similar social withdrawal scores. The factor structure of the poststroke sample differed from that of nonstroke elderly in that depressed mood items loaded with items for energy loss and memory problems.ConclusionDespite the fact that 62% of subjects scored ≥ 6 on the GDS, none were currently receiving assessment and/or treatment for their depressive symptoms. The frequency distribution and factor structure suggest that poststroke GDS scores reflect endorsement of functional losses such as decreased energy and impaired memory and subsequent feelings of helplessness, boredom and social withdrawal rather than decreased positive affect. Treatment should focus on dealing with these issues. Copyright © 2001 John Wiley & Sons, Ltd.
Neural representation of verb meaning: An fMRI study
Authors: Grossman Murray , Koenig Phyllis , DeVita Chris , Glosser Guila , Alsop David , Detre John , Gee James 
Published: August 2002

AbstractThe neural basis for verb comprehension has proven elusive, in part because of the limited range of verb categories that have been assessed. In the present study, 16 healthy young adults were probed for the meaning associated with verbs of MOTION and verbs of COGNITION. We observed distinct patterns of activation for each verb subcategory: MOTION verbs are associated with recruitment of left ventral temporal‐occipital cortex, bilateral prefrontal cortex and caudate, whereas COGNITION verbs are associated with left posterolateral temporal activation. These findings are consistent with the claim that the neural representations of verb subcategories are distinct. Although the “sensory‐motor” hypothesis may play a role in explaining activation associated with MOTION verbs, the left posterolateral temporal distribution of cortical activation associated with COGNITION verbs cannot be easily explained by the “sensory‐motor” hypothesis. We suggest that left posterolateral temporal activation supports aspects of lexical semantic processing concerned with the neural representation of propositional knowledge contributing to COGNITION verbs. Hum. Brain Mapping 15:124–134, 2002. © 2002 Wiley‐Liss, Inc.
Brief visual stimulation allows mapping of ocular dominance in visual cortex using fMRI
Authors: Goodyear Bradley G. , Menon Ravi S. 
Published: August 2002

AbstractWe have used high spatial resolution (0.55 mm × 0.55 mm) functional magnetic resonance imaging (fMRI) to show that when stimulus duration is brief (<6 sec), the hyperoxic hemodynamic response to neural activity can resolve the columnar architecture of ocular dominance within the primary visual cortex of humans. Our fMRI maps of ocular dominance columns are strikingly similar in appearance, size, and orientation to those reported in the literature using optical imaging of intrinsic signals (OIS) in animal cortex and histology of post‐mortem human specimens. We also demonstrate that under brief visual stimulation conditions, our results are consistent over repeated experiments. This is not the case for long duration stimuli (≥10 sec). A simulated random data set exhibited the same response properties as maps obtained when using these prolonged visual stimuli. Our results suggest that brief visual stimulation is essential for fMRI to successfully resolve ocular dominance columns using the hyperoxic phase of the hemodynamic response to neural activity at our prescribed spatial resolution. Hum. Brain Mapping 14:210–217, 2001. © 2001 Wiley‐Liss, Inc.
Changing the first line drug for malaria treatment—cost‐effectiveness analysis with highly uncertain inter‐temporal trade‐offs
Authors: Goodman Catherine A. , Coleman Paul G. , Mills Anne J. 
Published: August 2002

AbstractAccess to effective treatment would substantially reduce the burden of malaria in sub‐Saharan Africa, but resistance to chloroquine, the most commonly used first line drug, is now widespread. There has been considerable debate over the level of chloroquine resistance at which a new first line drug should be adopted. Two issues make this an extremely complex decision: it involves trade‐offs in costs and health outcomes over time; and many of the parameters are uncertain. A modelling approach was identified as appropriate for addressing these issues. The costs and effects of changing from chloroquine to sulphadoxine‐pyrimethamine (SP) as the first line drug were modelled over 10 years, allowing for growth in drug resistance. Probabilistic sensitivity analysis was used to allow for the high levels of parameter uncertainty. The optimal year of switch was highly dependent on both empirical values, such as initial resistance and resistance growth rates, and on subjective values, such as the time preferences of policy‐makers. It was not possible to provide policy‐makers with a definitive threshold resistance level at which to switch, but the model can be used as an analytical tool to structure the problem, explore trade‐offs, and identify areas for which data are lacking. Copyright © 2001 John Wiley & Sons, Ltd.
Vascularization in the transition area between free grafted soft tissues and pre‐irradiated graft bed tissues following preoperative radiotherapy in the head and neck region
Authors: Schultze‐Mosgau Stefan , Grabenbauer Gerhard G. , Radespiel‐Troöger Martin , Wiltfang Joörg , Ries Jutta , Neukam Friedrich Wilhelm , Roödel Franz 
Published: August 2002

AbstractBackgroundThe healing of free vascular grafts in a pre‐irradiated graft bed is characterized by an increased risk of wound healing disorders. For that reason, the aim of this study was to examine quantitative vascularization pattern between free vascular grafts and the pre‐irradiated graft bed as a function of the preoperative irradiation dose.MethodsA total of 217 free microvascular hard and soft tissue grafts were used within 199 patients in the head and neck region to cover defects after ablative tumor surgery. Seventy‐six patients (group 1) had no prior radiation (RT), 50 patients (group 2) were treated with preoperative radiochemotherapy using 40 to 50 Gy and 5‐FU/cisplatin, and 73 patients (group 3) had prior RT (60–70 Gy) between 1 and 7 years before surgery. After healing of the grafts, samples were taken from 42 patients from the graft, the irradiated graft bed, and the transition area between graft and irradiated graft bed. Samples were analyzed as follows: capillary sprouting, structural changes, and distribution patterns were analyzed by immunohistochemical staining (CD34 labeling of capillary endothelium). Three histological sections (2–4 μm) per sample were examined histomorphometrically (ratio capillary area/total area, capillary lumen, and the number of capillaries) by (National Institute of Health) NIH‐image‐digitized measurements. A statistical analysis was performed using the Kruskal‐Wallis and Mann‐Whitney test (two‐tailed p < .05).ResultsThe success rate of vascular grafts in group 1 (0 Gy) was 94%, in group 2 (40–50 Gy/5‐FU/cisplatin) 90%, in group 3 (60–70 Gy) 84%. In contrast to groups 1 and 2, group 3 showed qualitatively reduced and more irregular capillary distribution with more marked pericapillary fibrosis in the irradiated tissue. Quantitatively, the ratio capillary area/total area, as a marker of improved capillarization, was significantly reduced in group 3 (median 0.01; IQR 0.02) compared with group 1 (median 0.53; IQR 0.32) and group 2 (median 0.44; IQR 1.40) (p < .001).ConclusionAfter preoperative RT, vascularization of the graft bed decreased continuously as a function of the total dose and time after RT. The results strongly advocate the use of a primary reconstruction after a time interval between 4 and 6 weeks following preoperative RT and suggest the use of a total radiation dose of 40 to 50 Gy. © 2002 John Wiley & Sons, Inc. Head Neck 24: 42–51, 2002.