bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nodulation and N2 fixation of faba bean (Vicia faba L.) after soil amendment with crop residues
Authors: Kadiata Bakach Dikand , Yan Feng , Schubert Sven 
Published: December 2002

AbstractThe effect of prior soil amendment with different N sources at 50 mg N (kg soil)—1 on nodulation and N2 fixation of faba bean (Vicia faba L. cv. Troy) using wheat (Triticum aestivum L. cv. Star) as reference crop was assessed in a pot experiment. Four treatments viz legume manure (LEGM) as clover shoots, cereal manure (CEREM) as barley straw, N fertilizer (FERT‐N) as Ca(NO3)2, and no‐manure control (NOMAN) were investigated consecutively at 45, 70, and 90 days after sowing (DAS). Faba bean nodulated profusely, with an increase on average from 629 nodules per pot at 45 DAS to nearly 2.3‐ and 3.3‐fold at 70 and 90 DAS, respectively. Low nodule numbers and nodule dry matter occurred under FERT‐N and CEREM, whereas high values were found for NOMAN and LEGM. Soil amendment affected percent N2 fixation in relation to N source and plant age. Highest percent N2 fixation (≥ 90 %) was found under the lowest N‐supplying amendments, no‐manure, and cereal manure, respectively. FERT‐N depressed N2 fixation particularly at 45 DAS when N2 fixation was reduced to as low as 23 %. The rise in N2 fixation thereafter suggests that faba bean adjusted after depletion of mineral N in the soil. N2 fixation was also decreased after cereal straw application, even though N concentration in faba bean plants was high. The results indicate that plant residues, both with high and low N concentration, applied to soil to raise its fertility may interfere with N2 fixation of faba bean.
Stage of development affects penetration of calcium chloride into apple fruits
Authors: Schlegel Thomas K. , Schönherr Jörg 
Published: December 2002

AbstractUsing young fruits or fruit segments, rates of penetration of 45CaCl2 across apple fruit cuticles (Malus x domestica) were studied during fruit development in two consecutive years (’︁Golden Delicious’ in 2000, ’︁Cox Orange Pippin’ and ’︁Boskoop’ in 2001). The aqueous donor solutions contained 5 g l—1 CaCl2 and 0.2 g l—1 Glucopon 215 CSUP as wetter. A droplet (5 μl) was applied to each fruit disc and allowed to dry within 1 h. Amounts penetrated were estimated immediately after droplet drying (0 h) and after 6 and 24 h penetration, respectively. Temperature during penetration was 20 �C and 100 % humidity was maintained throughout the experiment, once the droplet had dried. Rates of penetration were greatly affected by the stage of fruit development. With all varieties tested, highest rates were measured during the early stages of fruit development (before June drop) when approx. 100 % of the CaCl2 applied penetrated within 24 h. After June drop, when trichomes had vanished and most stomata developed into lenticels, penetration rates decreased rapidly and large variability among the samples developed. This pattern was similar with all three varieties. The involvement of trichomes, stomata, and lenticels as preferential sites of penetration of calcium chloride across the apple fruit cuticles is discussed. Using a model calculation, it is argued that ten or more spray applications are needed to significantly increase calcium contents of apples. This has two causes: Only a small fraction of the spray liquid is intercepted by the fruits, and penetration can be rather slow.
Detectability enhancement of spectrophotometric detectors by the use of multidimensional gas chromatography
Authors: Medina Juan Carlos , Griffith James , Houston K. Ray , Winniford Bill 
Published: December 2002

AbstractMultidimensional gas chromatography (2D GC) is demonstrated as a way to improve limits of detectability of spectrophotometric detectors. UV and IR detectors are generally less sensitive than mass spectrometers or other GC detectors. This has placed some limitations on the useful capabilities provided by spectrophotometric detectors, such as the ability to provide structure‐related information for a particular analyte. In this paper, we report results from interfacing a 2D GC instrument to a UV detector. Symmetry factor and the ratio of retention time divided by peak width did not show deterioration of the quality of chromatography when a megabore column was used with this detector. Furthermore, an increase in the limits of detectability over that attainable in a single‐column system was realized by using the 2D GC system. However, the low flow (1 mL/min) imposed by the use of a microbore column (250 μm ID) caused significant tailing when the UV detector was used.
Factors influencing chromatographic data in fast gas chromatography with on‐column injection
Authors: Matisová Eva , Šimeková Mária , Hrouzková Svetlana , Korytár Peter , Dömötörová Milena 
Published: December 2002

AbstractThe use of larger volume injection with on‐column injection and fast GC commercial instrumentation was evaluated with the model mixture of n‐alkanes of a broad range of volatility (C10–C28). The presented configuration allows introduction of 40–80‐fold larger sample volumes without any distortion of peak shapes compared to “usual” fast GC set‐ups using narrow‐bore columns. A normal‐bore retention gap (1–5 m×0.32 mm ID) was coupled to a narrow‐bore (5 m×0.1 mm ID×0.4 μm film thickness) analytical column using a standard press‐fit connector. The connection was tight and reliable, and hence suitable for hydrogen as carrier gas. The effect of pre‐column and analytical column connector, injection volume, pre‐column length, column inlet pressure, and analyte volatility on peak shape, peak broadening, and focusing are discussed. The precision of chromatographic data measurements and peak capacity under optimised temperature programmed conditions for fast separations with large volume injection were found to be very good. The presented fast GC set‐up with on‐column injection extends the applicability of the technique to trace analysis.
Polymer electrostatics: detection and speciation of trapped electric charges by electric probe and analytical electron microscopy
Authors: Galembeck Fernando , Alberto Carlos , Leite Paula , do Carmo Maria , da Silva V.M. , Keslarek Amauri José , Alberto Carlos , Costa Rodrigues , Teixeira‐Neto Érico , Rippel Márcia Maria , Braga Melissa 
Published: December 2002

AbstractThis work reviews new probe and electron microscopy approaches for the detection of charged domains in insulating polymers, as well as for the identification of the charge‐bearing species: scanning electric potential microscopy (SEPM), electric force microscopy (EFM) and energy‐loss spectroscopy imaging in the transmission electron microscope (ESI‐TEM). The SEPM and EFM micrographs show patterned domains bearing excess electric charges and extending for tens of nanometers, in polymer latex particles and films. The charged species are identified by ESI‐TEM as emulsion polymerization initiator and surfactant residues, as well as the associated counter‐ions. Charged domains are also observed in common thermoplastic polymers, producing unexpectedly large electric potential gradients.
Hybrid organic‐inorganic polymer networks based on the copolymerization of methacryloxypropyl‐silsesquioxanes and styrene
Authors: Eisenberg Patricia , Lucas Juan C. , Williams Roberta J.J. 
Published: December 2002

AbstractSilsesquioxanes synthesized by the condensation of (3‐methacryloxypropyl)trimethoxysilane with concentrated formic acid, were copolymerized with styrene using benzoyl peroxide as initiator. When the ratio of styrene (S) to methacrylic (M) unsaturations was S/M > 1, the reaction attained an almost complete conversion as shown by the total reaction heat determined by differential scanning calorimetry. Several properties of the resulting hybrid organic‐inorganic polymer networks were determined as a function of the silsesquioxane amount used in the formulation. Increasing the silsesquioxane fraction led to an increase of the glass transition temperature up to a point where devitrification was not observed prior to decomposition, an increase of the elastic modulus in the rubbery state, a decrease of the intensity of tan δ, and an increase of both Barcol hardness and thermal stability.
Compatibilization of elastomer‐based blends
Authors: Scares Bluma G. , Sirqueira Alex S. , Oliveira Marcia G. , Almeida Mauricio S.M. 
Published: December 2002

AbstractThe reactive compatibilization of ethylene‐propylene‐diene (EPDM)‐based dissimilar elastomer blends has been investigated in terms of mechanical properties and swelling degree. The use of mercapto‐functionalized copolymers resulted in an improvement of mechanical properties of natural rubber‐EPDM blends. The mercapto‐groups are able to react with the carbon‐carbon double bonds of the high diene rubber, resulting in a good interaction between phases. These interactions were confirmed by the amount of insoluble material obtained in non‐vulcanized blends. From dynamic mechanical properties and swelling degree, one can suggest a covulcanization process in these blends cured with sulfur‐based system.Blends composed by nitrile rubber with EPDM displayed good results in terms of mechanical properties when mercapto‐functionalized EVA was employed instead of functionalized EPDM, probably because of the higher polarity of the former associated to its lower viscosity. Additionally, an improvement on mechanical properties was also achieved by using EPDM functionalized with mercapto or anhydride groups in combination with nitrile rubber functionalized with epoxy or oxazoline groups.
Modulation of JB6 mouse epidermal cell transformation response by the prostaglandin F2α receptor
Authors: Weber Thomas J. , Markillie Lye M. , Chrisler William B. , Vielhauer George A. , Regan John W. 
Published: December 2002

AbstractProstaglandin F2α (PGF2α) modulates clonal selection processes in the mouse skin model of carcinogenesis. In this study we investigated whether JB6 mouse epidermal cells expressed a functional PGF2α receptor (FP) coupled with a cell‐transformation response. Treatment of JB6 cells with an FP agonist (fluprostenol) potently (pM‐nM) increased anchorage‐dependent and anchorage‐independent growth. Inositol phospholipid accumulation and extracellular signal–regulated kinase (Erk) activity were increased in cells treated with FP agonists, consistent with established FP‐related signal transduction. FP mRNA was detected by reverse transcription–polymerase chain reaction, and the average specific [3H]PGF2α binding was 8.25 ± 0.95 fmol/mg protein. Erk activity and colony size were increased by cotreatment of JB6 cells with epidermal growth factor (EGF) and fluprostenol to a greater extent than with either treatment alone, whereas the cotreatment effect on colony number appeared to be simply additive. Collectively, our data indicated that JB6 cells expressed a functional FP coupled with transformation‐related signal transduction and the regulation of clonal selection processes. Erk activity appears to be a convergence point in the EGF and FP pathways. The data raise the possibility that the FP contributes to clonal selection processes but probably plays a more important role as a response modifier. © 2002 Wiley‐Liss, Inc.
Expression, localization, and activity of glycogen synthase kinase 3β during mouse skin tumorigenesis
Authors: Leis Hugo , Segrelles Carmen , Ruiz Sergio , Santos Mirentxu , Paramio Jesús M. 
Published: December 2002

AbstractGlycogen synthase kinase 3 (GSK‐3) is a protein kinase that plays essential roles in the control of several developmental, metabolic, and apoptotic processes. Owing to its negative actions on several oncogenic insults, it has been considered a putative functional tumor suppressor. We studied the expression, activity, and localization of GSK‐3β during the process of chemically induced two‐stage mouse skin carcinogenesis and also in the tumors generated upon subcutaneous injection of Akt‐transformed keratinocytes. We found that GSK‐3 activity was downregulated at the later stages of promotion by tyrosine 216 dephosphorylation and serine 9 phosphorylation. The data obtained with Akt‐transformed keratinocytes clearly suggested the involvement of Akt in serine 9 phosphorylation of GSK‐3β. Finally, besides functional inactivation, significant basal activity of GSK‐3β was detected in all cases, indicating that this enzyme provides essential functions to malignant keratinocytes. © 2002 Wiley‐Liss, Inc.
Downregulation of expression of a novel cadherin molecule, T‐cadherin, in basal cell carcinoma of the skin
Authors: Takeuchi Tamotsu , Liang Sheng‐Ben , Ohtsuki Yuji 
Published: December 2002

AbstractT‐cadherin appears to act as a tumor‐suppressor factor in various cancers. Downregulation of T‐cadherin is caused by a combination of allelic loss and hypermethylation of the T‐cadherin promoter region and is related to cancer invasion. To elucidate the molecular mechanism of invasiveness of basal cell carcinoma of the skin, T‐cadherin expression was investigated in archival pathological tissue sections made up of normal counterparts of skin and various types of basal cell carcinoma. Immunohistochemical staining showed that T‐cadherin was not expressed in 38 of 51 (75%) basal cell carcinoma specimens, whereas normal counterparts of the skin appeared to express abundant T‐cadherin. Loss of heterozygosity in intron 1 of the T‐cadherin gene was found in four of 20 informative cases that did not express T‐cadherin. Aberrant methylation of the T‐cadherin promoter region also was found in six of 25 basal cell carcinomas by methylation‐specific polymerase chain reaction. In contrast, no structural alternations were found in two loss of heterozygosity–positive basal cell carcinomas on sequence analysis. These findings indicated that T‐cadherin expression was downregulated by a combination of allelic loss and aberrant methylation in basal cell carcinoma of the skin. Loss of T‐cadherin expression might be related to the biological behavior of basal cell carcinoma. In addition, results of the present study suggested that downregulation of T‐cadherin in various cancers might be related to tumor invasiveness rather than metastasis, because basal cell carcinoma of the skin principally lacks metastatic activity. © 2002 Wiley‐Liss, Inc.
Generation of free radicals and induction of DNA adducts by activation of heterocyclic aromatic amines via different metabolic pathways in vitro
Authors: Moonen Harald J. J. , Briedé Jacob J. , van Maanen Jan M. S. , Kleinjans Jos C. S. , de Kok Theo M. C. M. 
Published: December 2002

AbstractFood‐derived heterocyclic aromatic amines (HCAs) have proved to be carcinogenic in both rodents and nonhuman primates. Two different metabolic pathways are suggested for the metabolic activation of HCA. The hepatic pathway proceeds via a two‐step process involving N‐hydroxylation by cytochrome P4501A2 and subsequent O‐acetylation by N‐acetyltransferase‐2. An alternative pathway may be of particular interest in extrahepatic tissues and proceeds via one‐electron oxidation catalyzed by prostaglandin H synthase (PHS), rendering free‐radical metabolites. In this study, we investigated the metabolic activation of two HCAs, 2‐amino‐3‐methylimidazo[4,5‐f]quinoline (IQ) and 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP), by two different enzyme systems in vitro, generating different primary and secondary reactive metabolites. Rat liver S9 mix and PHS were used as the activating system and represent the hepatic and extrahepatic pathways, respectively. Electron‐spin resonance spectroscopy showed that both IQ and PhIP exerted inhibiting effects on PHS‐mediated formation of hydroxyl radicals during the conversion of arachidonic acid to prostaglandins. Evidence for the formation of HCA free radicals was presented in an indirect way by the formation of glutathione‐derived thiyl radicals, with purified PHS as the activating system. Activation by S9 mix did not result in the formation of detectable radical metabolites, showing that the two metabolic routes primarily led to the formation of different metabolites. In all electron‐spin resonance experiments, IQ appeared to be more effective than PhIP. In contrasts, DNA adduct analysis by means of 32P‐postlabeling showed similar adduct patterns for S9 and PHS in single‐stranded and double‐stranded salmon testes DNA after incubation with PhIP, indicating the ultimate formation of a common reactive intermediate. For IQ, activation by PHS led to an additional adduct spot that was not present after S9 activation. Furthermore, activation of IQ resulted in higher adduct levels compared with PhIP for both activation pathways. Overall, adduct levels were higher in single‐stranded DNA than double‐stranded DNA. Our results showed that the hepatic and extrahepatic pathways resulted in different primary metabolites, while the ultimate formation of a similar reactive intermediate for PhIP, possibly an arylnitrenium ion, suggested that both pathways could play an important role in the onset of carcinogenesis. © 2002 Wiley‐Liss, Inc.
Mechanism of action of a dominant negative c‐jun mutant in inhibiting activator protein‐1 activation
Authors: Thompson Eric J. , Gupta Ashok , Stratton M. Suzanne , Bowden G. Tim 
Published: December 2002

AbstractThe dominant negative c‐jun TAM‐67 has been shown to inhibit tumor promotion induced by 12‐O‐tetradecanoylphorbol‐13‐acetate and okadaic acid (OA). To better understand this phenomenon, we investigated the mechanism of action of TAM‐67 in response to OA. To identify the mechanism of action, we used a 6xHis‐tagged TAM‐67 as well as chimeric constructs of TAM‐67 that either cannot bind DNA or cannot heterodimerize with wild‐type transcription factors. The results of these studies indicated that TAM‐67 acts by blocking or squelching. The results of elecrophoretic mobility‐shift assays showed that TAM‐67 must act by squelching in response to OA, as TAM‐67 cannot be found in DNA‐binding complexes. We then identified some of the proteins with which TAM‐67 interacts. They include all members of the jun and fos families as well as the cAMP response element binding protein, activating transcription factor‐1, activating transcription factor‐2, and RelA (p65). Thus, we have shown that TAM‐67 squelches the induction of activating transcription factor‐1 transactivation in response to OA and that TAM‐67 is capable of interacting with proteins that control transactivation by binding to the 12‐O‐tetradecanoylphorbol‐13‐acetate response element, cAMP response element and nuclear factor‐κB sites. © 2002 Wiley‐Liss, Inc.
Gradual deregulation and loss of PCPH expression in the progression of human laryngeal neoplasia
Authors: Blánquez María José , Regadera Javier , Mariño Javier , Newman Robert E. , Notario Vicente 
Published: December 2002

AbstractPCPH is a gene involved in the regulation of eukaryotic cell proliferation and stress response. Recently, analyses of human and animal solid tumors and cell lines suggested that PCPH protein deregulation may participate in neoplastic progression. To test this possibility, we first examined PCPH expression in several laryngeal carcinoma cell lines by Western analysis. The results showed the presence of altered PCPH polypeptides in these cells, accompanied by the loss of the PCPH form present in normal laryngeal epithelial cells, a deregulated expression pattern similar to that reported previously. We then analyzed PCPH expression in 59 dysplastic lesions of the human larynx, representative of the mild, moderate, and severe stages of the disease. Immunohistochemical data showed that, compared with normal laryngeal mucosa, PCPH expression in the dysplastic samples was associated with areas of epithelial cell maturation rather than with regions of increased proliferation. Furthermore, PCPH expression decreased parallel to the increase in cellular atypia of the dysplastic samples: PCPH either was expressed at very low levels or not expressed in cases of severe dysplasia/carcinoma in situ. This trend toward loss of PCPH expression along malignant progression of the larynx was confirmed by the low to null expression of PCPH in samples of invasive laryngeal carcinoma and by the complete absence of PCPH immunostaining in a laryngeal carcinoma–derived liver metastasis. These results indicated that PCPH protein analysis might allow for the distinction between grades of laryngeal dysplasia. In addition, detection of altered PCPH polypeptides by Western analysis potentially can be applied to the early identification of laryngeal squamous cell carcinoma. © 2002 Wiley‐Liss, Inc.
High b‐value q‐space analyzed diffusion‐weighted MRS and MRI in neuronal tissues – a technical review
Authors: Cohen Yoram , Assaf Yaniv 
Published: December 2002

AbstractThis review deals with high b‐value q‐space diffusion‐weighted MRI (DW‐MRI) of neuronal tissues. It is well documented that at sufficiently high b‐values (and high q‐values) neuronal water signal decay in diffusion experiments is not mono‐exponential. This implies the existence of more than one apparent diffusing component or evidence for restriction. The assignment of the different apparent diffusing components to real physical entities is not straightforward. However, the apparent slow diffusing component that was found to be restricted to a compartment of a few microns, if originating mainly from a specific pool and if assigned correctly, may potentially be used to obtain more specific MR images with regard to specific pathologies of the CNS. This review examines the utility of analyzing high b‐value diffusion MRS and MRI data using the q‐space approach introduced by Callaghan and by Cory and Garroway. This approach provides displacement probability maps that emphasize, at long diffusion times, the characteristics of the apparent slow diffusing component. Examples from excised spinal cord, where the experimental conditions for which the q‐space analysis of MR diffusion data was developed can be met or approached will be presented. Then examples from human MS patients, where q‐space requirement for the short gradient pulse is clearly violated, are presented. In the excised spinal cord studies, this approach was used to study spinal cord maturation and trauma, and was found to be more sensitive than other conventional methods in following spinal cord degeneration in an experimental model of vascular dementia (VaD). High b‐value q‐space DWI was also recently used to study healthy and MS diseased human brains. This approach was found to be very sensitive to the disease load in MS, compared with other conventional MRI methods, especially in the normal appearing white matter (NAWM) of MS brains. Finally, the potential diagnostic capacity embedded in high b‐value q‐space analyzed diffusion MR images is discussed. The potentials and caveats of this approach are outlined and experimental data are presented that show the effect of violating the short gradient pulse (SGP) approximation on the extracted parameters from the q‐space analysis. Copyright © 2002 John Wiley & Sons, Ltd.