bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the thickness of coatings by means of a new XRF spectrometer
Authors: Fiorini C. , Gianoncelli A. , Longoni A. , Zaraga F. 
Published: October 2002

AbstractWe propose a new, compact XRF spectrometer conceived for the determination of the thickness of a coating deposited on a substrate. The analysis technique is based on the detection, at different angles of observation, of the fluorescence emitted by the substrate and absorbed through the coating. With respect to other methods, the measurement is independent of the XRF analysis of the coating, which need not even be fluorescent. Moreover, no calibration of the instrument with standard samples is required. A key feature of the proposed spectrometer is represented by the use of a Silicon Drift Detector (SDD) for the first time in this kind of measurement. The SDD is characterized by a very low output capacitance (of the order of 0.1 pF), independent of the active area of the device, which allows one to achieve a lower electronic noise with respect to a conventional silicon diode of equivalent area and thickness. Based on a Peltier‐cooled SDD, a compact spectrometer, characterized by an energy resolution of about 155 eV FWHM at 6 keV (at about −10°C), was realized. The analysis technique and the spectrometer compactness make this instrument suitable for on‐line, non‐destructive quality control in the semiconductor and mechanical industries. In this paper the measurement technique is described and the first experimental results obtained on samples composed of a substrate coated with a layer of different thickness are presented. Copyright © 2002 John Wiley & Sons, Ltd.
Performance of a new compact EDXRF spectrometer for aerosol analysis
Authors: Samek Lucyna , Injuk Jasna , Van Espen Piet , Van Grieken René 
Published: October 2002

AbstractThe performance of a compact and economic MiniPal EDXRF spectrometer (Philips Analytical, Almelo, The Netherlands) was investigated for the analysis of aerosol filters. A standard operating procedure for the XRF analysis of aerosols on filters was followed. First, different aerosol grade filters (Nuclepore, Whatman, Teflon) and Mylar foil were measured to evaluate the blank values. The initial results showed high apparent blank values of Fe, Ni, Cu and Zn for all the substrates, which was attributed to the measurement platform of the commercial system, made out of brass coated with nickel. To overcome this problem, the measurement platform was covered with high‐purity silver paint. In this way, the high blank values, introduced by the system itself, were considerably reduced. The second step was the selection of the best tube‐filter to use, among the standard ones already incorporated in the MiniPal. The optimum tube‐filters were found to be Mo and Ag for medium‐Z elements and Al for low‐Z elements. In the calibration procedure a series of thin reference standards were used. The calibration procedure was evaluated by analysing aerosol samples measured previously with a Tracor EDXRF unit. Based on the analysis of these samples, the accuracy was on average 20% depending on the element and concentration. The precision of the analysis was better than 5%. Detection limits for aerosol samples measured with the MiniPal system are in the range from 3 ng cm−2 (Al, Si) in a helium atmosphere, which is much better than with conventional EDXRF units, to 2 ng cm−2 (heavy metals), which is comparable to those for conventional EDXRF units. Measurements in a helium atmosphere were performed for both standard and aerosol samples. For light element analysis, an improvement of the detection limit by a factor of 2.5 was achieved when helium was used. Copyright © 2002 John Wiley & Sons, Ltd.
Behavioral effects of environmental enrichment on harbor seals (Phoca vitulina concolor) and gray seals (Halichoerus grypus)
Authors: Hunter Sue A. , Bay Monika S. , Martin Michele L. , Hatfield Jeff S. 
Published: October 2002

AbstractZoos and aquariums have been incorporating environmental enrichment into their animal care programs for the past 30 years to increase mental stimulation and promote natural behaviors. However, most attempts to document the effects of enrichment on animal behavior have focused on terrestrial mammals. Staff at the National Aquarium in Baltimore conducted an investigation of the behavioral effects of enrichment on the seven harbor seals and two gray seals housed in the aquarium's outdoor seal exhibit. We expected that enrichment would change the amount of time the animals spent engaged in specific behaviors. The behaviors recorded were: resting in water, resting hauled out, maintenance, breeding display, breeding behavior, aggression, pattern swimming, random swimming, exploration, and out of sight. Activity levels (random swimming and exploration) were expected to increase, while stereotypic behaviors (pattern swimming) were expected to decrease. The frequency and duration of behaviors were documented for 90 hr in both the control phase (without enrichment) and the experimental phase (with enrichment). Statistically significant differences (P<0.05) in the time spent in pattern swimming, random swimming, exploration, and out of sight were observed between the two phases. With enrichment, pattern swimming and out of sight decreased, while random swimming and exploration behavior increased. These findings demonstrate that enrichment can promote behaviors (random swimming and exploration) that are likely to be normal for phocids in the wild, and that may contribute to the behavioral complexity of these seals in captivity. Zoo Biol 21:375–387, 2002. © 2002 Wiley‐Liss, Inc.
Constraints on the temperature sensitivity of global soil respiration from the observed interannual variability in atmospheric CO2
Authors: Jones Chris D. , Cox Peter M. 
Published: October 2002

AbstractCarbon cycle feedbacks have been shown to be very important in predicting climate change over the next century. The response of the terrestrial carbon cycle to climate change depends on the competition between increased respiration due to warmer temperatures and increased uptake due to elevated CO2levels. Whether the terrestrial carbon cycle remains a sink for anthropogenic carbon, or switches to become a source, depends particularly on the response of soil respiration to temperature. Here we use observed global atmospheric CO2concentration to constrain the behaviour of soil respiration in a coupled climate–carbon cycle GCM. Copyright © 2001 British Crown Copyright.
Cytoskeletal changes and induction of embryogenesis in microspore and pollen cultures of Brassica napus L.
Authors: Hause B. , Hause G. , Pechan P. , van Lammeren A. A. M. 
Published: October 2002

AbstractMicrospores and pollen of Brassica napus were cultured under conditions leading to embryo formation. Concomitant changes in cytoskeletal configurations were analysed. The microfilamental cytoskeleton exhibited a loss of polarity in embryogenic cells but cytochalasin treatment revealed that microfilaments do not influence embryogenesis. Two embryogenic pathways started from microspores and were either characterized by turned division planes or by division when the nucleus was in the cell centre. In both cases microtubules clearly exhibited new arrangements and likely played a major role in newly induced symmetrical division. In pollen, embryogenic development started in the vegetative cell provided the generative cell was arrested near the pollen wall. The concomitant disappearance of defined microtubular arrays is likely to be responsible for the positioning of the cell.
Study of localization of the protein‐synthesizing machinery along actin filament bundles.
Authors: Shestakova Elena A. , Motuz Ludmila P. , Minin Alexander A. , Gavrilova Lydia P. 
Published: October 2002

AbstractIndirect immunofluorescent microscopy was used to study the distribution of elongation factor 2 (eEF‐2) in fixed human skin diploid and mouse embryo fibroblasts. It was found earlier that some of the eEF‐2 ribosomes and initiation factor 2 (eIF‐2) are co‐localized with a part of the actin microfilament bundles in these cells (Gavrilova et al., 1987; Shestakova et al., 1991). Here it has been shown that inhibition of protein synthesis either by inactivation of eEF‐2 itself with diphtheria toxin or by inactivation of ribosomes with ricin does not abolish the distribution of eEF‐2 along the actin microfilament bundles. At the same time, the disassembly of actin microfilaments by cytochalasin D results also in the disappearance of eEF‐2‐carrying threads. This means that the eEF‐2‐carrying threads do not exist per se, and that the organization of eEF‐2 in visible "filaments" depends upon the integrity of the actin cytoskeleton.
Co‐localization of components of the protein‐synthesizing machinery with the cytoskeleton in G0‐arrested cells.
Authors: Shestakova Elena A. , Motuz Ludmila P. , Gavrilova Lydia P. 
Published: October 2002

AbstractThe distribution of eukaryotic elongation factor 2 (eEF‐2) in G0‐arrested fixed human skin diploid fibroblasts was studied by indirect immunofluorescent microscopy. It was found earlier that the main part of eEF‐2 in cycling cells was located near the nucleus in the endoplasm (Gavrilova et al., 1987). It has been demonstrated here that the transition from proliferation to the G0 phase of the cell cycle leads to the distribution of eEF‐2 mainly along the intermediate filaments and/or microtubules. Both in cycling and in G0‐arrested fibroblasts a portion of eEF‐2 is also co‐localized with actin microfilament bundles. The reversion of the cells from the G0 phase to proliferation is accompanied by rearrangement of the actin cytoskeleton and reversal to the original pattern of eEF‐2 distribution. It is likely that the different types of cytoskeleton in eukaryotic cells can be involved in organization of protein‐synthesizing machinery.
Changes on protein expression associated with salinity tolerance in Brassica cell cultures
Authors: Martín J. P. , Elavummoottil O. C. , Moreno M. L. 
Published: October 2002

AbstractThe synthesis of proteins from salt‐tolerant Brassica oleracea L. var. botrytis L. subvar. cauliflora (Gars.) DC. (cauliflower) cell cultures is modified in relation to controls in several features. There are nine newly induced polypeptides in tolerant cultures (absent in control conditions). Some of them are only present under low salt levels (85 mM NaCl). Another group seems to be representative of moderate and high salt levels (170 and 255 mM NaCl), and a third group is present in all the salt conditions tested. On the other hand, the synthesis of most of the polypeptides present in control conditions is modified in salt‐tolerant cultures by increasing, decreasing or stopping their synthesis in any of the tested conditions. The relationship between these changes in Brassica and other plant systems is discussed.
Changes in sensitivity of human tumour cells to growth inhibition by proteinase inhibitors.
Authors: Scott G. Kenneth , Tse Cynthia A. 
Published: October 2002

ABSTRACTInhibition of a cell‐surface proteinase can inhibit the growth of many normal human cell types in culture. Some tumour cells are also sensitive to proteinase inhibitors, but others are resistant, and continue to grow in the presence of these inhibitors. Here we describe two human tumour cell lines which convert from the sensitive to the resistant state. In one case, the conversion occurs during routine passaging, but, in the other, it is determined by growth conditions, and is reversible.
SYNTHESIS OF LACTOFERRIN AND CASEIN BY EXPLANTS OF BOVINE MAMMARY TISSUE
Authors: Hurley W. L. , Aslam M. , Hegarty H. M. , Morkoç A. 
Published: October 2002

ABSTRACTSynthesis of lactoferrin and casein by the bovine mammary gland was determined in an experimental model where lactation was maintained in one mammary half, while involution was induced in the contralateral half. Culture of explants with prolactin had no consistent effect on synthesis of casein or lactoferrin in tissue from either mammary half. Endotoxin and tumor necrosis factor‐α generally decreased synthesis of casein and lactoferrin, suggesting that these inflammatory mediators are not directly responsible for increasing lactoferrin synthesis during mammary inflammation or involution. Synthesis of lactoferrin was increased and casein decreased in the involuting mammary half vs. the lactating half. These results suggest that local factors in the mammary gland play a role in the regulation of lactoferrin synthesis during involution.
Human hypertensive placenta contains an increased amount of Na, K‐ATPase with higher affinity for cardiac glycosides
Authors: Amler Evžen , Cester Nelvio , Salvolini Eleonora , Staffolani Roberto , Burkhard Martin , Mazzanti Laura , Kotyk Arnošt , Romanini Carlo 
Published: October 2002

ABSTRACTPlacentas of women suffering from pregnancy‐induced hypertension (PIH) were found to contain a greater amount of Na,K‐ATPase molecules, estimated from anthroyl ouabain binding, than normotensive individuals. Both the microsomal fraction of placental cells and purified Na,K‐ATPase showed an increased affinity for the specific inhibitor ouabain which, in the case of the microsomes, bound with a dissociation constant of 0.9 nM as compared with 3.4 nM in the controls. Likewise, the dissociation constant of the ouabain complex with purified Na,K‐ATPase was about 3.5 times lower in the hypertensive patients. The differences are apparently caused by a different microenvironment of the ouabain‐binding site, as reflected in the quantum yield of bound anthroyl ouabain. If an endogenous digitalis‐like factor is present in the body fluids to regulate Na,K‐ATPase activity, the present results render its role quite plausible.
Both glucose‐type monosaccharides and one of their metabolites are required for activation of yeast plasma membrane H+‐ATPase.
Authors: Kotyk Arnost , Georghiou Georghios 
Published: October 2002

ABSTRACTSaccharomyces cerevisiae and Schizosaccharomyces pombe cells were grown on D‐glucose, D‐galactose, D‐fructose, D‐mannose, maltose, trehalose and ethanol. All these substrates were separately added to cells thus grown and the onset and rate of acidification mediated by the plasma membrane H+‐ATPase were determined. Irrespective of the growth substrate, the best triggers of acidification in both species were fructose, mannose and glucose (with average rates of 5.2, 5.0 and 4.8 nmol H+ per min per mg dry weight, respectively, for S. cerevisiae, and 4.5, 6.8 and 5.8 for S. pombe). These were followed in S. cerevisiae by galactose in Gal‐, Man‐ and Tre‐grown cells (about 0.40 nmol H+) and by maltose in Mal‐ and Tre‐grown cells (about 0.15 nmol H+). Trehalose elicited some response in only ethanol‐grown cells while ethanol itself was completely ineffective in activating the H+‐ATPase. In S. pombe, however, maltose caused an acidification rate of 3.6 nmol H+ per min per mg dry wt., followed by EtOH (().38), Gal (0.13) and Tre (0.05). 6‐Deoxy‐D‐glucose and 2‐deoxy‐D‐glucose, not metabolized or improperly metabolized analogues of glucose, had no effect whatsoever. ‐ It appears that the sensor triggering the ATPase‐activating pathway is a complex responding both to a glucose‐type sugar (Glc, Man, Fru) and possibly identical with one of the glucose carriers, and to one of its metabolites, most probably fructose‐6‐phosphate.
Is the recovery of microtubule orientation in pea roots dependent on the cell wall?
Authors: Holdaway N. J. , White R. G. , Overall R. L. 
Published: October 2002

AbstractThis study tested several aspects of a model proposed by Williamson (1990, 1991) in which stresses in plant cell walls, detected by stress‐receptive portions of inelastic cellulose microfibrils, orient microtubules via interactions with cell wall‐linked transmembrane proteins. Young expanding cells of pea root tips have highly ordered transverse arrays of microtubules oriented perpendicular to the direction of cell expansion. The recovery of these ordered MT arrays after depolymerisation with oryzalin was assessed. It was shown that treating roots with disruptors of microfibril synthesis (2,6‐dichlorobenzonitrile and calcofluor white) or the disruption of Arg‐Gly‐Asp (RGD)‐mediated wall‐membrane links did not affect the orientation of recovering microtubule arrays. Furthermore, cell wall stresses themselves appeared unnecessary for regeneration of transverse arrays. The relevance of these findings to Williamson's hypothesis is discussed.
Cytokeratin expression in human respiratory epithelium of nasal polyps and turbinates
Authors: Hicks Wesley , Ward Robert , Edelstein David , Hall Leon , Albino Anthony , Hard Robert , Asch Bonnie 
Published: October 2002

ABSTRACTThe cytokertatins in respiratory epithelial cells (REC) of human nasal polyps and turbinates were analyzed by immunohistochemistry. Cytokeratin 19 (CK19) was present in all REC, CK5 and 14 were expressed primarily in basal cells, and CK7, 8, and 18 were found in suprabasal cells. Differences in cytoplasmic locations were also apparent among the individual cytokeratins. CK13 was not detected in any REC of these tissues. The results indicate the profile of cytokeratins in REC of human nasal polyps and turbinates is essentially identical to that of REC in the more distal respiratory tract.
KINESIN‐ASSOCIATED TRANSPORT IS INVOLVED IN THE REGULATION OF CELL ADHESION
Authors: KAVERINA IRINA N. , MININ ALEXANDER A. , GYOEVA FATIMA K. , VASILIEV JURY M. 
Published: October 2002

AbstractIt has been recently shown that depolymerization of microtubules induces the elongation of focal contacts at the leading edge. On the other hand, cell shape and pseudopodial activity were found to depend on the microtubule‐based motor kinesin. In this paper, we examine whether kinesin is involved in controlling the dynamics of adhesive structures at the cell surface. Microinjection of an antiblocking kinesin activityin vitrocauses focal contact elongation similar to the effect of microtubule‐depolymerizing drugs. Thus, the role of microtubules in cell adhesion lies in the supporting kinesin‐based transport to the adhesion sites.
E‐CADHERIN EXPRESSION CAN ALTER THE SPECIFICITY OF GAP JUNCTION FORMATION
Authors: PROWSE DAVID M. , CADWALLADER G. P. , PITTS J. D. 
Published: October 2002

AbstractSpecificity of gap junction formation produces communication compartments, groups of cells joined to each other by gap junctions (homologous communication) but more rarely to cells in adjacent compartments (heterologous communication). Specificity of junction formation can be studied in mixed cultures of different cell types. In these model systems, compartmentation is often associated with sorting out, a process that produces separate domains of the different cells. The borders of the physically distinct domains correlate with the functional boundaries of the communication compartments. Compartments have also been observedin vivowhere they are believed to play a role in separating groups of cells following different differentiation pathways. Two classes of cell surface molecule, connexins and cell adhesion molecules, are candidates for a role in the control of specificity. A representative of each class appears to be necessary for gap junction formation and both are expressed in a tissue specific manner. We have shown that mixed cultures of rat epithelial (BRL) cells and rat (BICR) fibroblasts show specificity, form communication compartments and sort out. Both cell types express the same connexin (connexin 43) but different cell adhesion molecules (BRL, P‐cadherin and 125‐kDa N‐cadherin; BICR, 140‐kDa N‐cadherin). Transfection of both cell types with E‐cadherin results in a 10‐fold increase in heterologous communication. These data suggest that E‐cadherin plays a role in the control of specificity of gap junction formation.
TYROSINE KINASE INHIBITORS REVERSE BUTYRATE STIMULATION OF HUMAN CACO‐2 INTESTINAL EPITHELIAL CELL ALKALINE PHOSPHATASE BUT NOT BUTYRATE PROMOTION OF DIPEPTIDYL DIPEPTIDASE
Authors: BASSON MARC D. , HONG FU 
Published: October 2002

AbstractShort chain fatty acids such as sodium butyrate are concentrated in the colonic lumen and may protect against colon carcinogenesis by maintaining colonocytic differentiation, but the mechanisms by which they act are not fully understood. It has recently been suggested that short chain fatty acids modulate cellular tyrosine kinase activity in addition to altering chromatin structure via regulation of histone acetylation and DNA methylation. Therefore, the authors evaluated the influence of tyrosine kinase inhibition on the effects of 10mM butyrate on human Caco‐2 intestinal epithelial differentiation, using alkaline phosphatase and dipeptidyl dipeptidase specific activity as markers of differentiation, and two tyrosine kinase inhibitors, of different mechanisms of action and different effects on Caco‐2 brush border enzyme specific activity, to block tyrosine kinase activity. As expected, butyrate stimulated both alkaline phosphatase and dipeptidyl dipeptidase specific activity. The tyrosine kinase inhibitors prevented, and indeed one inhibitor reversed the effects of butyrate on alkaline phosphatase specific activity. However, tyrosine kinase inhibition did not prevent butyrate stimulation of dipeptidyl dipeptidase specific activity. Different pathways are likely to regulate the effects of butyrate on expression of these two brush border enzymes. Butyrate stimulation of alkaline phosphatase, but not dipeptidyl dipeptidase, may involve tyrosine phosphorylation signaling.
SULPHATE INFLUX IN THE ERYTHROCYTES OF NORMOTENSIVE, DIABETIC AND HYPERTENSIVE PATIENTS
Authors: Romano L. , Scuteri A. , Gugliotta T. , Romano P. , De Luca G. , Sidoti A. , Amato A. 
Published: October 2002

AbstractThis study aimed to show that modifications in intracellular metabolism are implicated in the pathophysiology of diabetes mellitus and essential hypertension. In fact, total magnesium, calcium, sodium and potassium concentrations, measured in the erythrocytes of normotensive, diabetic and hypertensive patients, have given the following results: a lower intracellular potassium concentration in the erythrocytes of diabetic and hypertensive patients than the erythrocytes of normotensive patients and a more elevated sodium, magnesium, calcium concentrations in the erythrocytes of diabetic and hypertensive patients than the normotensive.Because of the importance of Mg2+ and Ca2+ in metabolic enzyme regulation and their interaction with both Hb and band 3 protein, we examined SO2−4 kinetic influx in the erythrocytes of normotensive, hypertensive and diabetic patients. The kinetic plots showed different profiles over the three groups and the fluxes were found to be 0.024, 0.061 and 0.072mmol×(l cells×min)−1 in normotensive, hypertensive and diabetic patients, respectively. We also found that the Vmax and Km of sulphate influx, obtained by Hofstee plots, increased in the erythrocytes of hypertensive and diabetic patients compared with control cells. In contrast, sulphate influx in the erythrocytes of diabetic and hypertensive patients in the presence of Nifedipine, a calcium antagonist, showed no difference either in the rate constants or in the kinetic profiles, compared to the normotensive control subjects.
Radiocarbon Ages of Soils and Charcoal in Late Wisconsinan Loess, South-Central Nebraska
Authors: May David W. , Holen Steven R. 
Published: October 2002

AbstractThe Farmdale Soil occurs below late Wisconsinan loess throughout the U.S. Midwest. At the La Sena site in the central Great Plains, humates in the Farmdale Interstadial Soil have a corrected age of 21,000 yr B.P. Humates in a buried Bt horizon and a bulk sample of overlying loess 2.5 m above the Farmdale Interstadial Soil have ages of 17,000 and 19,000 yr B.P., respectively. In the Republican River Valley Picea (spruce) charcoal is common in the lower meter of Peoria loess. Near Bloomington, Nebraska, humates from burned organic matter only 60 cm above the base of Peoria loess have a corrected age of ca. 19,000 yr B.P.