bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of freezing on Young’s modulus for twigs of coniferous and deciduous trees and shrubs
Authors: Umbanhowar, Charles E. , Lambert Allison M. , VanDelinder Lindsay 
Published: March 2008

The mechanical behavior of frozen twigs may be important in understanding twig breakage during winter owing to wind or snow loading. While below 0 °C temperatures are known to increase the stiffness of wood, few studies have examined the effects of cold temperatures on the biomechanical properties of twigs of both coniferous and deciduous woody plants. In this study, we compared the effects of –11 to –14 °C temperatures on the Young’s modulus (E) of fine twigs of 14 species of woody plants. Twigs were 13%–304% stiffer when frozen than when thawed at room temperature (21 °C), with conifers showing the greatest percentage increase in stiffness. In general, more flexible twigs (when thawed) showed the greatest percentage increase in E when frozen. Greater stiffening of more flexible twigs may in part be the result of higher water contents but may also reflect differences in the relative importance of supercooling and extracellular freezing, with greater frozen stiffness associated with freezing. Our work suggests a direct link between cell physiology and whole organ biomechanics, and highlights reasons for differences in susceptibility to breakage due to wind or snow loading.
Mass loss and nutrient dynamics of coarse woody debris in three Rocky Mountain coniferous forests: 21 year results
Authors: Herrmann Steffen , Prescott Cindy E. 
Published: March 2008

Mass loss and changes in C, N, and P concentrations were measured in 20 cm long log segments of lodgepole pine ( Pinus contorta Dougl. ex Loud.), white spruce ( Picea glauca (Moench) Voss), and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) that had been placed in three Rocky Mountain coniferous forests 21 years earlier. Pine, spruce, and fir lost 76%, 39%, and 64%, respectively, of their initial mass during the 21 years. The corresponding mean decay rates (k) were 0.072, 0.024 and 0.052·year–1. The decay patterns of pine and spruce were similar with the highest k between 6 and 14 years. Fir k increased during the course of decomposition with the highest rate between 14 and 21 years. The correlation between original dry mass and k was negative for pine (r = –0.28), positive for fir (r = 0.35), and not significant for spruce. C/N, C/P, and N/P ratios declined and converged to a similar value in relation to mass loss for all three species. The N/P ratios of logs of all three species stabilized at about 19. These findings indicate that patterns of wood decay are difficult to predict (even with 14 year data), and so models that incorporate wood-decay estimates will be associated with considerable uncertainty.
The importance of catchment slope to soil water N and C concentrations in riparian zones: implications for riparian buffer width
Authors: Hazlett P. , Broad K. , Gordon A. , Sibley P. , Buttle J. , Larmer D. 
Published: March 2008

Buffer zones are an important component of forest-management strategies and are thought to reduce the impact of nutrients released after harvesting on water quality. Conceptually, steep slopes have shorter water residence times than shallow slopes, have a reduced capacity to moderate water quality, and therefore, require wider buffers. Carbon and N concentrations in riparian zone shallow soil water at 30 cm depth and lake water were measured on shallow and steep slopes at the Esker Lakes Research Area in northeastern Ontario to determine if nutrient concentrations were correlated to catchment terrain attributes. Field measured slope, slope class obtained from a triangular irregular network model, and upslope contributing area and topographic index calculated from a digital elevation model were calculated for each sampling location. Modeled terrain properties, including those currently used during forest-management planning, were not significantly correlated with soil water N and C concentrations, whereas only dissolved organic carbon levels were significantly greater on field measured steep slopes. Forest species composition and soil N levels were positively correlated with soil water N concentrations. These results from the undisturbed boreal ecosystem highlight the potential limitation of using only catchment slope as a tool for prescribing riparian buffers during harvesting when considering terrestrial nutrient export.
Growth, resource storage, and adaptation to drought in California and eastern Mediterranean oak seedlings
Authors: Grünzweig José M. , Carmel Yohay , Riov Joseph , Sever Nava , McCreary Douglas D. , Flather Curtis H. 
Published: March 2008

Low recruitment of new plants as currently observed in several California oak species might partly result from insufficient storage of vital resources (reduced ability to regrow after disturbance) or from low adaptation to environmental stress, such as drought. We conducted two studies under divergent environmental conditions to compare seedlings of California oaks with ecologically equivalent species from the eastern Mediterranean region, where recruitment has been substantial over the past 25–30 years. Resource concentrations (nonstructural carbohydrates and nitrogen) in taproots and the ratio of root resource content to shoot biomass did not provide evidence that Californian oak seedlings have smaller reserves for resprouting than eastern Mediterranean species in these studies. However, we observed lower seedling survival among California species, when compared with Mediterranean species, under conditions of higher drought stress. In the California deciduous Quercus douglasii Hook. & Arn., water-use efficiency as measured by leaf gas exchange and leaf δ13C was lower compared with its Mediterranean equivalent Quercus ithaburensis Decne. In addition, stomatal conductance in the California evergreen Quercus agrifolia Née appeared to be less sensitive to vapor pressure deficit than in its Mediterranean equivalent Quercus calliprinos Webb. Our results suggest lower adaptation to drought in the California species tested here as compared with Mediterranean species, which will negatively impact recruitment of oaks from California under the currently drier soil conditions.
Effects of riparian forest thinning by two types of mechanical harvest on stream fish and habitat in northern Minnesota
Authors: Hemstad Nathaniel A. , Merten Eric C. , Newman Raymond M. 
Published: March 2008

The response of fish communities and stream habitat to four riparian harvest treatments was studied in north-central Minnesota to determine if riparian harvest with two different harvest systems degrades stream systems. Treatments included control (no harvest), riparian control, cut-to-length riparian thin, and tree length riparian thin. Fish and habitat data were collected from 50 m reaches above, within, and downstream of each treatment 1 year preharvest (1997) and 3 years postharvest (1998–2000). Repeated measures analysis revealed few effects due to treatment; however, there was a 6%–10% significant reduction in canopy cover. Percent fine sediments increased significantly (15%) system-wide following forest harvest and persisted through 2000. This increase in fine sediments was correlated with a decrease in fish biotic integrity (r = –0.31). Habitat and fish variables were influenced more by year-to-year variation than by harvest treatment, suggesting that factors operating at a broader basin-wide scale may influence fish and habitat or mask any site-level harvest effects in this low-gradient stream system. Residual riparian basal areas ≥12.3m2/ha along reaches ≤200 m in length may be adequate to protect fish and habitat in these low-gradient streams, but basin-wide effects of harvest deserve more scrutiny.
Effect of cutting intensity on microenvironmental conditions and regeneration dynamics in yellow birch – conifer stands
Authors: Prévost Marcel 
Published: March 2008

This paper presents the 5 year results of different cutting intensities (removal of 0%, 40%, 50%, 60%, and 100% of the basal area) applied in two mixed yellow birch ( Betula alleghaniensis Britt.) – conifer stands of eastern Quebec, Canada. Two sites 90 km apart were used: Armagh and Duchesnay. Each site had four replicates of the treatments in a randomized block design. The effect on light availability was similar in the two sites: the 0%, 40%, 50%, 60%, and 100% cuts transmitting a mean of 5%, 21%, 26%, 30%, and 94% of full light, respectively, during the first summer. Soil temperature increased only in the 100% cut (4−5 °C, maximum daily temperature). Soil disturbance during harvest was higher at Duchesnay than at Armagh, which clearly improved seedbed receptivity, particularly to yellow birch. After 5 years, treated areas contained 21 000 to 48 300 seedlings/ha at Duchesnay compared with 5500 – 10 500 seedlings/ha at Armagh. Significant losses of coniferous advance growth were observed at both sites, but a subsequent seedling recruitment occurred only at Duchesnay. Red spruce ( Picea rubens Sarg.) showed superior establishment in the 60% cut (4400 seedlings/ha) than under other cutting intensities (1600–2100 seedlings/ha), whereas balsam fir ( Abies balsamea (L.) Mill.) responded well to all partial cutting treatments. At both sites, pin cherry ( Prunus pensylvanica L.f.) was the main competing species in the 100% cut, whereas densities of the preestablished mountain maple ( Acer spicatum Lamb.) and striped maple ( Acer pensylvanicum L.) either remained the same or increased in the partial cuts.
Allometry and size structure of trees in two ancient snow forests in coastal British Columbia
Authors: Parish Roberta , Nigh Gordon D. , Antos Joseph A. 
Published: March 2008

Shade-tolerant trees that start in the understory but ultimately reach the canopy persist through different microhabitat conditions during their ontogeny. We evaluate how the height to diameter ratio and the crown ratio (crown length/tree height) change during development and differ among four coniferous species ( Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes, Chamaecyparis nootkatensis (D. Don) Spach, Tsuga mertensiana (Bong.) Carrière, and Tsuga heterophylla (Ref.) Sarg.) in ancient forests. At two sites, we measured diameter, height, and height to the base of live crown for trees ≥4.0 cm diameter at breast height in four 0.25 ha plots. For each species, we constructed models of height based on diameter and crown length using part of the data for model development and part as the test data set. Models predicting tree height were effective for all species, and adding crown length considerably improved the prediction over diameter alone. The height to diameter ratio increased until the subcanopy and then decreased for two shade-tolerant species (A. amabilis and T. heterophylla) but decreased linearly throughout ontogeny for C. nootkatensis. Crown ratio increased as trees became larger except for C. nootkatensis, where the reverse occurred. Differences in allometric relationship among species reflect patterns of crown development and also suggest different approaches to a common structural constraint in these forests: heavy snow loads.
Rad9 Has a Functional Role in Human Prostate Carcinogenesis
Authors: Zhu Aiping , Zhang Charles Xia , Lieberman Howard B. 
Published: March 2008

Abstract
Prostate cancer is currently the most common type of neoplasm found in American men, other than skin cancer, and is the second leading cause of cancer death in males. Because cell cycle checkpoint proteins stabilize the genome, the relationship of one such protein, Rad9, to prostate cancer was investigated. We found that four prostate cancer cell lines (CWR22, DU145, LNCaP, and PC-3), relative to PrEC normal prostate cells, have aberrantly high levels of Rad9 protein. The 3′-end region of intron 2 of Rad9 in DU145 cells is hypermethylated at CpG islands, and treatment with 5′-aza-2′-deoxycytidine restores near-normal levels of methylation and reduces Rad9 protein abundance. Southern blot analyses indicate that PC-3 cells contain an amplified Rad9 copy number. Therefore, we provide evidence that Rad9 levels are high in prostate cancer cells due at least in part to aberrant methylation or gene amplification. The effectiveness of small interfering RNA to lower Rad9 protein levels in CWR22, DU145, and PC-3 cells correlated with reduction of tumorigenicity in nude mice, indicating that Rad9 actively contributes to the disease. Rad9 protein levels were high in 153 of 339 human prostate tumor biopsy samples examined and detectable in only 2 of 52 noncancerous prostate tissues. There was a strong correlation between Rad9 protein abundance and cancer stage. Rad9 protein level can thus provide a biomarker for advanced prostate cancer and is causally related to the disease, suggesting the potential for developing novel diagnostic, prognostic, and therapeutic tools based on detection or manipulation of Rad9 protein abundance. [Cancer Res 2008;68(5):1267–74]
Inhibition of the Ras-Net (Elk-3) Pathway by a Novel Pyrazole that Affects Microtubules
Authors: Wasylyk Christine , Zheng Hong , Castell Christelle , Debussche Laurent , Multon Marie-Christine , Wasylyk Bohdan 
Published: March 2008

Abstract
Net (Elk-3/SAP-2/Erp) is a transcription factor that is phosphorylated and activated by the Ras–extracellular signal-regulated kinase (Erk) signaling pathway and is involved in wound healing, angiogenesis, and tumor growth. In a cell-based screen for small molecule inhibitors of Ras activation of Net transcriptional activity, we identified a novel pyrazole, XRP44X. XRP44X inhibits fibroblast growth factor 2 (FGF-2)–induced Net phosphorylation by the Ras-Erk signaling upstream from Ras. It also binds to the colchicine-binding site of tubulin, depolymerizes microtubules, stimulates cell membrane blebbing, and affects the morphology of the actin skeleton. Interestingly, Combretastin-A4, which produces similar effects on the cytoskeleton, also inhibits FGF-2 Ras-Net signaling. This differs from other classes of agents that target microtubules, which have either little effect (vincristine) or no effect (docetaxel and nocodazole) on the Ras-Net pathway. XRP44X inhibits various cellular properties, including cell growth, cell cycle progression, and aortal sprouting, similar to other molecules that bind to the tubulin colchicine site. XRP44X has the potentially interesting property of connecting two important pathways involved in cell transformation and may thereby represent an interesting class of molecules that could be developed for cancer treatment. [Cancer Res 2008;68(5):1275–83]
Selective Inhibition of Histone Deacetylase 2 Silences Progesterone Receptor–Mediated Signaling
Authors: Biçaku Elona , Marchion Douglas C. , Schmitt Morgen L. , Münster Pamela N. 
Published: March 2008

Abstract
Several histone deacetylases (HDAC) are involved in estrogen receptor (ER)–mediated gene transactivation, and HDAC inhibitors have been reported to restore sensitivity to antihormonal therapy. The modulation of ER is the most promising approach to ER-expressing breast cancers. Recent studies further suggest a critical role of the progesterone receptor (PR) on ER signaling. Although HDAC inhibitors modulate ER, little is known about their effects on PR. We evaluated the roles of specific HDAC isoenzymes and their inhibition on both ER and PR signaling and their importance in response to endocrine therapy. The roles of individual HDAC isoenzymes on ER and PR expression and their functions were evaluated by depletion of select HDAC enzymes using siRNA or pharmacologic inhibition. Cotreatment of breast cancer cell lines with HDAC inhibitors and the antiestrogen, tamoxifen, resulted in synergistic antitumor activity with simultaneous depletion of both ER and PR. Selective inhibition of HDAC2, but not HDAC1 or HDAC6, was sufficient to potentiate tamoxifen-induced apoptosis in ER/PR-positive cells. Depletion of HDAC1 and HDAC6 was associated with down-regulation of ER but not PR. Only the selective depletion of HDAC2 siRNA down-regulated both ER and PR expression, and was sufficient to potentiate tamoxifen. Selective depletion of HDAC2 resulted in simultaneous depletion of ER and PR, and potentiated the effects of antihormonal therapy in ER-positive cells. A more effective pharmacologic inhibition of HDAC2 and evaluation of HDAC2 and PR as therapeutic targets or as predictive markers in hormonal therapy may be considered when combining HDAC inhibitors and hormonal therapy. [Cancer Res 2008;68(5):1513–9]
p21Waf1/Cip1 Expression by Curcumin in U-87MG Human Glioma Cells: Role of Early Growth Response-1 Expression
Authors: Choi Byeong Hyeok , Kim Chang Gun , Bae Young-Seuk , Lim Yoongho , Lee Young Han , Shin Soon Young 
Published: March 2008

Abstract
Curcumin, a natural compound, is a well-known chemopreventive agent with potent anticarcinogenic activity in a wide variety of tumor cells. Curcumin inhibits cancer cell proliferation in part by suppressing cyclin D1 and inducing expression of the cyclin-dependent kinase inhibitor p21Waf1/Cip1. Both p53-dependent and p53-independent mechanisms regulate p21Waf1/Cip1 expression, but the mechanism by which curcumin regulates p21Waf1/Cip1 expression remains unknown. Here, we report that transcription of the p21Waf1/Cip1 gene is activated by early growth response-1 (Egr-1) independently of p53 in response to curcumin treatment in U-87MG human glioblastoma cells. Egr-1 is a transcription factor that helps regulate differentiation, growth, and apoptosis in many cell types. Egr-1 expression is induced by curcumin through extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK), but not the p38, mitogen-activated protein kinase (MAPK) pathways, which mediate the transactivation of Elk-1. Transient expression of Egr-1 enhanced curcumin-induced p21Waf1/Cip1 promoter activity, whereas suppression of Egr-1 expression by small interfering RNA abrogated the ability of curcumin to induce p21Waf1/Cip1 promoter activity. In addition, stable knockdown of Egr-1 expression in U-87MG cells suppressed curcumin-induced p21 expression. Our results indicate that ERK and JNK MAPK/Elk-1/Egr-1 signal cascade is required for p53-independent transcriptional activation of p21Waf1/Cip1 in response to curcumin in U-87MG human glioblastoma cells. [Cancer Res 2008;68(5):1369–77]
Endosomal Proteases Influence the Repertoire of MAGE-A3 Epitopes RecognizedIn vivoby CD4+ T Cells
Authors: Marturano Jill , Longhi Renato , Russo Vincenzo , Protti Maria Pia 
Published: March 2008

AbstractLittle is known about the repertoire of MAGE-A3 CD4+ T-cell epitopes recognized in vivo by neoplastic patients and how antigen processing influences epitope formation. Here, we first show that MAGE-A3–specific CD4+ T cells are present in the blood of advanced melanoma patients. MAGE-A3111-125, MAGE-A3191-205, and MAGE-A3281-300 were recognized by 7, 6, and 5 of the 11 patients tested, respectively. MAGE-A3146-160 and MAGE-A3171-185 were also recognized in two and one cases, whereas no recognition of MAGE-A3161-175 and MAGE-A3243-258 was observed. Cytokines produced were mainly interleukin 5 and/or granulocyte macrophage colony-stimulating factor, suggesting impairment of productive polarized Th1 responses. Secondly, proteases inhibitors were used to modulate in vitro the recognition by CD4+ T-cells clones of dendritic cells loaded with MAGE-A3–expressing cell lysates. We found that formation of MAGE-A3111-125 depended on both leupeptin-sensitive and pepstatin-sensitive proteases. In contrast, we found that MAGE-A3161-175, which was never recognized ex vivo, was formed by leupeptin but destroyed by pepstatin-sensitive proteases. Collectively, our results show that (a) anti–MAGE-A3 CD4+ T-cell immunity develops in vivo in neoplastic patients and is focused toward immunodominant epitopes, (b) the response in advanced disease is skewed toward a Th2 type, and (c) endosomal/lysosomal proteases in dendritic cells influence the repertoire of the epitopes recognized. [Cancer Res 2008;68(5):1555–62]
Anti–Tumor Necrosis Factor Therapy Inhibits Pancreatic Tumor Growth and Metastasis
Authors: Egberts Jan-Hendrik , Cloosters Vera , Noack Andreas , Schniewind Bodo , Thon Lutz , Klose Stefanie , Kettler Bastian , von Forstner Corinna , Kneitz Christian , Tepel Jürgen , Adam Dieter , Wajant Harald , Kalthoff Holger , Trauzold Anna 
Published: March 2008

Abstract
Chronic inflammation has been implicated in the pathogenesis of many severe autoimmune disorders, as well as in diabetes, pulmonary diseases, and cancer. Inflammation accompanies most solid cancers including pancreatic ductal adenocarcinoma (PDAC), one of the most fatal cancers with surgery being the only curative therapeutic approach currently available. In the present work, we investigated the role of the major proinflammatory cytokine tumor necrosis factor α (TNFα) in the malignancy of PDAC cells in vitro and in vivo. In vitro, TNFα strongly increased invasiveness of Colo357, BxPc3, and PancTuI cells and showed only moderate antiproliferative effect. TNFα treatment of mice bearing orthotopically growing PDAC tumors led to dramatically enhanced tumor growth and metastasis. Notably, we found that PDAC cells themselves secrete TNFα. Although inhibition of TNFα with infliximab or etanercept only marginally affected proliferation and invasiveness of PDAC cells in vitro, both reagents exerted strong antitumoral effects in vivo. In severe combined immunodeficient mice with orthotopically growing Colo357, BxPc3, or PancTuI tumors, human-specific anti-TNF antibody infliximab reduced tumor growth and metastasis by about 30% and 50%, respectively. Importantly, in a PDAC resection model performed with PancTuI cells, we found an even stronger therapeutic effect for both anti-TNF compounds. Infliximab and etanercept reduced the number of liver metastases by 69% and 42%, respectively, as well as volumes of recurrent tumors by 73% and 51%. Thus, tumor cell–derived TNFα plays a profound role in malignancy of PDAC, and inhibition of TNFα represents a promising therapeutic option particularly in adjuvant therapy after subtotal pancreatectomy. [Cancer Res 2008;68(5):1443–50]
Co-Targeting Insulin-Like Growth Factor I Receptor and HER2: Dramatic Effects of HER2 Inhibitors on Nonoverexpressing Breast Cancer
Authors: Chakraborty Ashok K. , Liang Ke , DiGiovanna Michael P. 
Published: March 2008

Abstract
The insulin-like growth factor I receptor (IGFIR) and HER2 display important signaling interactions in breast cancer. We examined the effect of combinations of antagonists of these receptors using two human breast cancer cell lines: BT474 (HER2+, IGFIR low) and MCF7 (HER2 low, IGFIR high). In BT474 cells, growth was inhibited by HER2 antagonists but not by IGFIR antagonists; however, IGFIR antagonists enhanced the effect of HER2 inhibitors. In MCF7 cells, growth was inhibited by IGFIR antagonists but not by HER2 antagonists; however, HER2 antagonism enhanced the effect of IGFIR inhibitors. Synergistic inhibition of soft agar growth was also observed. Although HER2 and IGFIR antagonists individually only minimally affected cell cycle, their combination gave a small enhancement of their effects. No single receptor-targeting drug was capable of inducing apoptosis, but combining antagonists of both receptors induced a dramatic degree of apoptosis in both cell lines. Induction of apoptosis was most striking in MCF7 cells using a Herceptin/IGFIR antagonist combination despite these cells being HER2 nonoverexpressing. Toward understanding the mechanism of these effects, we detected coassociation IGFIR and HER2 in both cell lines. Specific inhibitors of one of these receptors could cross-inhibit the activity of the other. Targeting both receptors gave the maximal inhibition of their downstream extracellular signal-regulated kinase 1/2 and AKT signaling pathways. Hence, such drug combinations may be clinically useful and may be beneficial even in tumors in which single drugs are inactive, as exemplified by the effect of the HER2/IGFIR inhibitor combination in HER2 nonoverexpressing MCF7 cells. [Cancer Res 2008;68(5):1538–45]