bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dopamine regulates cell cycle regulatory proteins via cAMP, Ca2+/PKC, MAPKs, and NF‐κB in mouse embryonic stem cells
Authors: Lee Min Young , Heo Jung Sun , Han Ho Jae 
Published: May 2006

AbstractThis study examined the effect of dopamine on DNA synthesis and its related signal cascades in mouse embryonic stem (ES) cells. Dopamine inhibited DNA synthesis in both a dose‐ and time‐dependent manner. Dopamine, SKF 38393 (D1 receptor agonist), and quinpirole (D2 receptor agonist) decreased the level of [3H]‐thymidine incorporation. The level of cyclic adenosine 3, 5‐monophosphate (cAMP) was increased by SKF 38393 but not by quinpirole. The protein kinase C (PKC) protein was translocated from the cytosolic fraction to the membrane compartment by dopamine. Dopamine also increased [Ca2+]i, which was blocked by EGTA (an extracellular Ca2+ chelator), BAPTA‐AM (an intracellular Ca2+ chelator), nifedipine (a L‐type Ca2+ channel blocker), SQ 22536 [an adenylyl cyclase (AC) inhibitor] and neomycin [a phospholipase C (PLC) inhibitor]. Dopamine, SKF 38393, and quinpirole increased the level of p44/42 mitogen‐activated protein kinases (MAPKs), p38 MAPK, and stress‐activated protein kinase/Jun‐N‐terminal kinase (SAPK/JNK) phosphorylation. Dopamine also increased level of H2O2 formation and activated the transcription factor family NF‐κB. Moreover, SKF 38393, quinpirole, and dopamine inhibited cell cycle regulatory proteins, which is consistent with the change in the level of [3H]‐thymidine incorporation observed. The dopamine‐induced decrease in cyclin E, cyclin‐dependent protein kinase‐2 (CDK‐2), and cyclin D1, CDK‐4 were blocked by pertussis toxin (G protein inhibitor), SQ 22536, neomycin, bisindolylmaleimide I (PKC inhibitor), SB 203580 (p38 MAPK inhibitor), PD 98059 (p44/42 inhibitor), and SP 600125 (SAPK/JNK inhibitor). In conclusion, dopamine inhibits DNA synthesis in mouse ES cells via the cAMP, Ca2+/PKC, MAPKs, and NF‐κB signaling pathways. J. Cell. Physiol. 208: 399–406, 2006. © 2006 Wiley‐Liss, Inc.
Targeting cyclooxygenase‐2 for prevention and therapy of colorectal cancer
Authors: Sinicrope Frank A 
Published: May 2006

AbstractCyclooxygenase‐2 (COX‐2) is an inducible enzyme that regulates prostaglandin synthesis and is overexpressed at sites of inflammation and in several epithelial cancers. A causal link for COX‐2 in epithelial tumorigenesis was shown in genetically manipulated animal models of colon and breast carcinoma. Studies have elucidated the regulation of COX‐2 expression and have identified EP receptors through which prostanoids exert their biological effects. Mechanistic studies indicated that COX‐2 is involved in apoptosis resistance, angiogenesis, and tumor cell invasiveness, which appear to contribute to its effects in tumorigenesis. Furthermore, forced COX‐2 expression has been shown to suppress apoptosis by modulating the level of death receptor 5 (DR5) and this effect was reversed by a COX inhibitor. COX enzymes are targets for cancer prevention as shown by the observation that nonselective COX and selective COX‐2 inhibitors have been reported to effectively prevent experimental colon cancer and can regress colorectal polyps in patients with familial adenomatous polyposis. This review will focus on the role of COX‐2 as a target for the prevention and treatment of human colorectal cancer. © 2006 Wiley‐Liss, Inc.
Retinoids, eye development, and maturation of visual function
Authors: Luo Tuanlian , Sakai Yasuo , Wagner Elisabeth , Dräger Ursula C. 
Published: May 2006

AbstractVitamin A is known to be critical for the beginning of eye development as well as for photoreception in the functional retina. Hardly anything, however, is known about whether retinoic acid (RA)‐regulated gene expression also plays a role in the long intervening period, during which the neurobiological retinal structure takes shape. The eye contains a highly intricate architecture of RA‐synthesizing (RALDH) and degrading (CYP26) enzymes. Whereas the RALDHs are integrated in the early molecular mechanisms through which the dorso‐ventral retina organization is established, the CYP26 enzymes are not necessary for this process and no molecular targets that match their retinal expression pattern have yet been identified. In this article we describe that CYP26 expression in the mouse is most distinctive during later stages of retina formation. Throughout development CYP26A1 degrades RA in a horizontal region that extends across the retina, but during later embryonic and postnatal retina maturation this function is reinforced by another enzyme, CYP26C1. RA applications at this stage do not affect the RALDHs but cause differential changes in CYP26 expression: Cyp26a1 is up‐regulated, but more rapidly by 9‐cis than all‐trans RA, Cyp26c1 is down‐regulated, and Cyp26b1, which is undetectable in the normal mouse retina, is strongly activated in retinal ganglion cells. The dynamic regulation in RA‐difference patterns by the CYP26 enzymes may set up spatial constellations for expression of genes involved in formation of retinal specializations for higher acuity vision, which are known to form over a prolonged period late in retina development. © 2006 Wiley Periodicals, Inc. J Neurobiol 66: 677–686, 2006
Retinoids and nonvertebrate chordate development
Authors: Fujiwara Shigeki 
Published: May 2006

AbstractRetinoic acid (RA) is required for the differentiation and morphogenesis of chordate‐specific features, such as the antero‐posterior regionalization of the dorsal hollow nerve cord and neural crest cells. RA receptors (RARs) have been reported exclusively in chordates, suggesting that the acquisition of the RAR gene was important for chordate evolution. A scenario is presented here for the establishment of an RAR‐mediated developmental regulatory system during the course of chordate evolution. In the common chordate ancestor, RAR came to control the spatial expression pattern of Hox genes in the ectoderm and endoderm along the antero‐posterior axis. In these germ layers, RA was required for the differentiation of epidermal sensory neurons and the morphogenesis of pharyngeal gill slits, respectively. As the diffuse epidermal nerve net in the chordate ancestor became centralized to form the dorsal nerve cord, the epidermal Hox expression pattern was carried into the central nervous system. Because the Hox code here came to specify neuronal identity along the antero‐posterior axis, RA became inextricably linked to the antero‐posterior patterning of the chordate central nervous system. © 2006 Wiley Periodicals, Inc. J Neurobiol 66: 645–652, 2006
Giant extrinsic negative thermal expansion in vanadium pentoxide nanocrystalline films
Authors: Bahgat A. A. , Al‐Hajry A. , El‐Desoky M. M. 
Published: May 2006

AbstractVanadium pentoxide gels, V2O5·1.6H2O, give rise to xerogel layers that exhibit a preferred orientation. X‐ray diffraction of this xerogel displays the 00l peaks typical of a turbostratic stacking of the V2O5 ribbons along a direction parallel to the substrate. The distance along the c‐axis is observed from the interlayer spacing to decrease continuously with increasing temperature up to 180 °C, as observed by high‐temperature X‐ray diffraction. This contraction may be described by an extrinsic mechanism of negative thermal expansion (NTE). The coefficient of NTE as large as –1.5 × 10–3 K–1 was observed. Full recovery of the interlayer spacing is obtained after cooling the sample to room temperature in open air, where water molecules are reabsorbed, indicating that the process is reversible and the heating process can be repeated without losing NTE. The structure of the xerogel was explored further using differential scanning calorimetry as well as infrared spectroscopy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AlGaN/AlN distributed bragg reflectors for deep ultraviolet wavelengths
Authors: Moe Craig G. , Wu Yuan , Piprek Joachim , Keller Stacia , Speck James S. , DenBaars Steven P. , Emerson David 
Published: May 2006

AbstractDistributed Bragg reflectors with up to 21 periods consisting of AlN and Al0.58Ga0.42N layers were grown by metalorganic chemical vapor deposition. A periodic structure and good interface quality was verified by both transmission electron microscopy and X‐ray diffraction, and was shown to be dependent on the composition of the underlying AlGaN base layer. Reflectivities of 49.8% at 285 nm and 66.6% at 245 nm were obtained with ten period superlattices. A reflectivity of 82.8% at 278 nm was measured for a twenty period structure. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carbon dynamics in an ultra‐oligotrophic epishelf lake (Beaver Lake, Antarctica) in summer
Authors: LAYBOURN‐PARRY JOHANNA , MADAN NANETTE J. , MARSHALL WILLIAM A. , MARCHANT HARVEY J. , WRIGHT SIMON W. 
Published: May 2006

Summary1. Microbial plankton dynamics in an ultra‐oligotrophic epishelf lake (Beaver Lake, Antarctica) were investigated over an austral summer (December 2002 to January 2003). The aim was to characterise carbon cycling in an environmentally extreme lake.2. The lake had an unusual temperature profile with peak temperatures of 1.3–1.9 °C between 20 and 25 m. Photosynthetically active radiation penetrated to the lake bottom (110 m) on occasions. The ice cover underwent marked thinning and melting during the study period.3. Chlorophyll a concentrations were consistently low, usually below 1 μg L−1, with highest concentrations close to the lake bottom, where the photosynthetic elements showed strong autofluorescence. Mean photosynthetic nanoflagellates ranged between 34.9 × 104 L−1 ± 33.5 (23rd December) and 130.9 × 104 L−1 ± 112.3 (4th December). Highest photosynthetic activity was usually recorded below 25 m. Rates of carbon fixation varied between 0.089 μg C L−1 h−1 ± 0.002 and 0.579 μg C L−1 h−1 ± 0.156. Primary production was limited by low temperature and orthophosphate availability.4. Mean bacterial concentration throughout the water column ranged between 9.3 × 107 L−1 ± 1.2 (23rd December) and 14.0 × 107 L−1 ± 1.8 (28th January). Bacterial production was low, less than 10% of primary production and ranged between 2.1 ng C L−1 h−1 ± 0.8 and 12 ng C L−1 h−1 ± 0.9. Highest rates coincided with times of highest primary production. On occasion dissolved organic carbon (DOC) concentrations dropped to 20 μg L−1, probably below accurate limits of detection, suggesting that carbon substratum and phosphorus may have limited bacterial growth.5. Heterotrophic nanoflagellates varied significantly over the summer from a mean of 26.6 × 104 L−1 ± 14.2 (23rd December) to 133.8 × 104 L−1 ± 33.5 (14th December). They imposed a significant grazing impact on the bacterioplankton, removing in excess of 100% of bacterial production in December.6. The total organic carbon pool [DOC and particulate organic carbon (POC)] was below 600 μg L−1. The ratio of DOC : POC ranged between 0.44 : 1 and 2.8 : 1 in the upper 40 m of the water column, and 1.8 : 1 and 3.7 : 1 in the lower waters. The microbial plankton contributed 1–29% of POC, thus detrital POC made up the largest fraction of the POC pool.7. Beaver Lake is an extreme lacustrine ecosystem where heterotrophic processes occasionally appear to be carbon limited. Significant summer ice‐melt, not seen in a previous opportunistic sampling, may be having an impact on the carbon cycle.
Effects of decadal climate change on zooplankton over the last 50 years in the western subarctic North Pacific
Authors: CHIBA SANAE , TADOKORO KAZUAKI , SUGISAKI HIROYA , SAINO TOSHIRO 
Published: May 2006

AbstractDecadal‐ to multi‐decadal variations have been reported in many regional ecosystems in the North Pacific, resulting in an increasing demand to elucidate the link between long‐term climatic forcing and marine ecosystems. We detected phenological and quantitative changes in the copepod community in response to the decadal climatic variation in the western subarctic North Pacific by analyzing the extensive zooplankton collection taken since the 1950s, the Odate Collection. Copepod species were classified into five seasonal groups depending on the timing of the annual peak in abundance. The abundance of the spring community gradually increased for the period 1960–2002. The spring–summer community also showed an increasing trend in May, but a decadal oscillation pattern of quasi‐30‐year cycles in July. Phenological changes coincided with the climate regime shift in the mid‐1970s, indicated by the Pacific decadal oscillation index (PDO). After the regime shift, the timing of the peak abundance was delayed one month, from March–April to April–May, in the spring community, whereas it peaked earlier, from June–July to May–June, in the spring–summer community, resulting in an overlap of the high productivity period for the two communities in May. Wintertime cooling, followed by rapid summertime warming, was considered to be responsible for delayed initiation and early termination of the productive season after the mid‐1970s. Another phenological shift, quite different from the previous decade, was observed in the mid‐1990s, when warm winters followed by cool summers lengthened the productive season. The results suggest that climatic forcing with different decadal cycles may operate independently during winter–spring and spring–summer to create seasonal and interannual variations in hydrographic conditions; thus, combinations of these seasonal processes may determine the annual biological productivity.
Maize DBF1‐interactor protein 1 containing an R3H domain is a potential regulator of DBF1 activity in stress responses
Authors: Saleh Abdelaty , Lumbreras Victoria , Lopez Cristina , Kizis Eva Dominguez‐Puigjaner, Dimosthenis , Pagès Montserrat 
Published: May 2006

SummaryThe maize dehydration‐responsive element (DRE)‐binding factor, DBF1, is a member of the Apetala 2/Ethylene Response Factor transcription factors family and is involved in the regulation of the ABA‐responsive gene rab17 through the DRE in an ABA‐dependent pathway. In this study we analysed the functionality of DBF1 in abiotic stress responses and found that Arabidopsis plants over‐expressing DBF1 were more tolerant to osmotic stress than control plants. In yeast two‐hybrid analyses, DBF1 interacted with DBF1‐interactor protein 1 (DIP1), a protein containing a conserved R3H single‐strand DNA‐binding domain. Subcellular localization of DIP1 showed that the protein fusion DIP1–Red Flourescent Protein (RFP) was mainly localized in the cytoplasm. However, after co‐transformation of DBF1–GFP and DIP1–RFP, both proteins co‐localized in the nucleus. Interestingly, when the N‐terminal DBF1–GFP was co‐expressed with DIP1–RFP, both proteins co‐localized predominantly in the cytoplasmic speckles observed for N‐terminal DBF1–GFP fusion protein. These results clearly show in vivo interaction of DBF1 with DIP1 in the cell and that this interaction is necessary for the nuclear localization of DIP1 protein. Analysis of the regulatory effect of the DBF1 and DIP1 interaction on the maize rab17 promoter activity indicated that co‐transfection of DBF1 with DIP1 enhances promoter activity in the absence of ABA treatment. We suggest that the regulated association of DBF1 and DIP1 may control the levels of target gene expression during stress conditions.
Newly qualified teachers’ learning related to their use of information and communication technology: a Swedish perspective
Authors: Andersson Sven B. 
Published: May 2006

AbstractThis qualitative study focuses on newly qualified teachers’ use of information and communication technology (ICT) as a tool for meeting the challenges of their everyday work. The overarching aim is to investigate whether they can contribute to new knowledge about learning in ICT contexts. Theoretical points of departure concern the changeable nature of learning in situations where ways of communicating knowledge and skills are changed. The study draws upon interviews and observations. The findings show intersections picturing the new technique as partly changing the circumstances for teaching, learning and collaboration between colleagues. The new teachers’ utterances show that ICT utilisation is extensive and exhibits great variation both among female and among male participants. Boundary‐crossing changes become visible in the collaboration between more experienced teachers and those who are newly qualified, especially when they work on a common development project. However, there are relatively few teachers who bring up active ICT use in connection with pupils’ learning. Changed roles because of ICT competence raise questions about the importance of systematic ICT features within teacher education. Many of the newly qualified teachers wish they had more knowledge about ICT and related techniques. Another question is whether newly qualified teachers who show interest in using the technique can take on the role as agents of change in their active and creative use of ICT.
Incidence rate of cervical cancer and precancerous lesions in East Azarbayjan, Iran
Authors: TABRIZI Ali Dastranj , ALIZADEH M , MELLI M Sayyah , JAFARI M , MADAREK Eos 
Published: May 2006

AbstractBackground:  Most of deaths from cervical cancer occur in low and medium income countries and opportunistic screening for cervical cancer does not decrease the incidence rate, thus organized mass screening is needed for control of the disease.Methods:  Pathology reports of cervical smears, biopsies, endocervical curettings, and hysterectomy specimens were collected from 22 pathology centers in East Azarbayjan during 2003–2004. Incidence rates for low‐grade squamous intraepithelial lesion (LSIL), high‐grade squamous intraepithelial lesion (HSIL) and cervical carcinoma were calculated by (Incidence/Population at risk) ×100 000. At risk population for cervical intraepithelial neoplasia (CIN) (between 18 and 64 years old) and invasive carcinoma of the cervix (between 30 and 64 years old) were 1 103 109 and 537 217 respectively.Result:  The adjusted incidence rates for LSIL, HSIL and cervical carcinoma were 3.68, 1.19 and 5.11 per 100 000 women at risk, respectively.Conclusion:  In contrast to developed countries we identified a higher incidence rate of cervical invasive cancers than preinvasive lesions, therefore, the importance and necessity of well organized mass screening in our country must be emphasized.
A Climatology of Midlatitude Continental Clouds from the ARM SGP Central Facility. Part II: Cloud Fraction and Surface Radiative Forcing
Authors: Dong Xiquan , Xi Baike , Minnis Patrick 
Published: May 2006

Abstract
Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Central Facility (SCF) are analyzed to determine the monthly and hourly variations of cloud fraction and radiative forcing between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layered low (0–3 km), middle (3–6 km), and high clouds (&gt;6 km) using ARM SCF ground-based paired lidar–radar measurements. Shortwave (SW) and longwave (LW) fluxes are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements with uncertainties of ∼10 W m−2. The annual averages of total and single-layered low-, middle-, and high-cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Both total- and low-cloud amounts peak during January and February and reach a minimum during July and August; high clouds occur more frequently than other types of clouds with a peak in summer. The average annual downwelling surface SW fluxes for total and low clouds (151 and 138 W m−2, respectively) are less than those under middle and high clouds (188 and 201 W m−2, respectively), but the downwelling LW fluxes (349 and 356 W m−2) underneath total and low clouds are greater than those from middle and high clouds (337 and 333 W m−2). Low clouds produce the largest LW warming (55 W m−2) and SW cooling (−91 W m−2) effects with maximum and minimum absolute values in spring and summer, respectively. High clouds have the smallest LW warming (17 W m−2) and SW cooling (−37 W m−2) effects at the surface. All-sky SW cloud radiative forcing (CRF) decreases and LW CRF increases with increasing cloud fraction with mean slopes of −0.984 and 0.616 W m−2 %−1, respectively. Over the entire diurnal cycle, clouds deplete the amount of surface insolation more than they add to the downwelling LW flux. The calculated CRFs do not appear to be significantly affected by uncertainties in data sampling and clear-sky screening. Traditionally, cloud radiative forcing includes not only the radiative impact of the hydrometeors, but also the changes in the environment. Taken together over the ARM SCF, changes in humidity and surface albedo between clear and cloudy conditions offset ∼20% of the NET radiative forcing caused by the cloud hydrometeors alone. Variations in water vapor, on average, account for 10% and 83% of the SW and LW CRFs, respectively, in total cloud cover conditions. The error analysis further reveals that the cloud hydrometeors dominate the SW CRF, while water vapor changes are most important for LW flux changes in cloudy skies. Similar studies over other locales are encouraged where water and surface albedo changes from clear to cloudy conditions may be much different than observed over the ARM SCF.
The generation and modulation of antigen-specific memory CD8 T cell responses
Authors: Jabbari Ali , Harty John T 
Published: May 2006

Abstract
The immune system has adapted to effect different mechanisms to combat the multitude of potential pathogens in our environment. In particular, CD8 T cells are participants in the immune response to intracellular pathogens, which include viruses, certain types of bacteria, and protozoa. Classified as members of the adaptive immune system, antigen-specific CD8 T cells after activation eventually form a pool of memory. Memory cells have an enhanced ability to protect against subsequent infections. The generation of antigen-specific CD8 T cells, therefore, is a potential approach in the design of vaccines, especially for those pathogens in which the humoral response is insufficient to protect the host.