bluuebunny/crossref_metadata_2025 huggingface dataset:
On the effects of traffic mixtures in direct broadcast satellite networks
Authors: Alagoz Fatih , Vojcic Branimir , AlRustamani Amina , Pickholtz Raymond
Published: October 2002

In this paper we present a multi‐criterion control simulation in a realistically complex environment of a satellite network, involving non‐symmetric up and downlinks. Direct broadcast satellite (DBS) networks carrying heterogeneous traffic is characterized with challenges, such as high traffic burstiness, wireless channel dynamics, and large, but limited capacity. On the other hand, there are system characteristics that can be leveraged to address these challenges such as in centralized topology, different levels in quality of service (QoS) and priorities, availability of side information about channel conditions, flexibility in delivery of delay insensitive traffic, etc. We have developed an adaptive resource allocation and management (ARAM) system that takes the advantage of such characteristics to maximize the utilization of the available capacity on the forward DBS link, while maintaining QoS in the presence of channel effects and congestion in the network. Since variable‐bit‐rate (VBR) video traffic is given priority over available‐bit‐rate (ABR) data traffic in the ARAM concept, in this paper we investigate the impact of the fraction of VBR load in overall load. Copyright © 2002 John Wiley & Sons, Ltd.
The development and evaluation of SHOKE2000: The PCI‐based FPGA card
Authors: Tanaka Koichiro , Arita Itsujiro
Published: October 2002

This paper describes a PCI‐based FPGA card, SHOKE2000, which was developed in order to study reconfigurable computing. Since the latest Field Programmable Gate Arrays (FPGAs) consist of input/output (I/O) configurable blocks as well as internal configurable logic blocks, they not only realize various user logic circuits but also connect with popular I/O standard easily. These features enable FPGAs to connect several devices with different interfaces, and thus new reconfigurable systems would be realizable by connecting the FPGAs with devices such as Digital Signal Processors (DSPs) and analog devices. This paper describes the basic functions of SHOKE2000, which was developed for realizing hybrid reconfigurable systems consisting of FPGAs, DSPs, and analog devices. We also present application examples of SHOKE2000, including a simple image recognition application, a distributed shared memory computer cluster, and teaching materials for computer education. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(9): 50–57, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10003
A dataflow computer which accelerates execution of sequential programs by precedent firing instructions
Authors: Nagase Hiroshi , Kameya Masakuni , Kawanami Takashi , Shiono Tomoki
Published: October 2002

In the dataflow machine, it is important to avoid degradation of performance in sequential processing, and it is important from the viewpoint of hardware scale to reduce the number of waiting operands. This paper demonstrates that processing performance is degraded by sequential processing in the switching process, and presents a method of remedy. Precedent firing control is proposed as a means of remedy, and it is shown by a simulation that the execution time and the total number of waiting operands can be reduced by the precedent firing control. Then the hardware scale is examined as an evaluation of precedent firing control. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(9): 68–77, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1153
Infrared reflection investigation of ion‐implanted and post‐implantation‐annealed epitaxially grown 6H‐SiC
Authors: Chang W. , Feng Z. C. , Lin J. , Liu R. , Wee A. T. S. , Tone K. , Zhao J. H.
Published: October 2002

Multiple energy Al+ and C+ ions were implanted into 6H‐SiC at room temperature (25°C) and elevated temperature (600°C), respectively, followed by 1550°C annealing for 30 min. Fourier transform infrared spectroscopy was used to evaluate the optical properties in the mid‐infrared range. An effective medium model, taking into account the presence of an implantation‐induced amorphous phase, was developed to establish the relationship between the changes of optical properties and modification of structure. Complete amorphization in the implanted layer was evidenced for room temperature implantation but no such case occurred at elevated temperature implantation. Elimination or decrease of the amorphous phase, via 1550°C annealing, was represented by the recovery of reflectance intensity and shape. Some structural and optical parameters, such as layer thickness and phonon damping constants of the amorphized SiC, were derived from fitting to measured data. Our work demonstrated the successful application of the Lorentz–Drude oscillator model in evaluating the lattice quality of the amorphous/crystalline SiC system. Copyright © 2002 John Wiley & Sons, Ltd.
Use of the absolute Auger parameter for vanadium in the study of the dielectric relaxation of cerium vanadate
Authors: Castle J. E. , Salvi A. M. , Decker F. , Moretti G.
Published: October 2002

X‐ray photoelectron spectroscopy (XPS) is known, mainly, as a technique for surface analysis. It is especially valued for interpretation of the chemical state by means of the chemical shift. This paper concerns the contribution to this shift from polarization of the ligands following core photoionization. Intercalation of ions such as lithium will influence the electronic polarizability of the oxygen ions and hence the value of the Auger parameter (AP). The AP is the difference in kinetic energy of the Auger peak in the spectrum and that of the principal photoelectron peak, calculated by an internationally accepted procedure. Thus, while obtaining the composition and chemical state of a compound one can also determine the polarizability of the material. Polarizability is crucial to the dielectric properties of oxides, such as refractive index, and is of value in optimizing intercalation compounds for use in optoelectronic devices. The use of this methodology will be illustrated using the vanadium ion in V2O5 and CeVO4, including its lithium‐intercalated form. Copyright © 2002 John Wiley & Sons, Ltd.
An application of the technique of density estimation in geographical epidemiology of goitre in the Muzaffarpur district of Bihar state of India
Authors: Mukherjee Ajit , Kumar Shiv , Mittal Rakesh , Saxena N. C.
Published: October 2002

The Gangetic plains in the Sub‐Himalayan belt of India are known endemic areas for goitre. The districts of Muzaffarpur and Sitamarhi in the eastern zone in the Bihar state of India showed a prevalence of over 30 per cent of goitre in a survey conducted by the Indian Council of Medical Research (ICMR) during 1983–1986. In the present paper, the technique of density estimation is employed to estimate the probability density functions of goitre‐affected and normal (non‐goitre) populations of the district of Muzaffarpur. The likelihood ratio is then plotted against distance of the villages from the Indo‐Nepal border keeping their distances from the headquarters in the district of Sitamarhi at fixed level. Using the odds form of Bayes rule, the posterior odds of goitre are calculated and compared at two given points. Copyright © 2002 John Wiley & Sons, Ltd.
MaDViWorld: a software framework for massively distributed virtual worlds
Authors: Fuhrer Patrik , Kouadri Mostéfaoui Ghita , Pasquier‐Rocha Jacques
Published: October 2002

The MaDViWorld project represents an original attempt to define an appropriate software architecture for supporting massively distributed virtual world systems. A non‐massively distributed virtual world system is typically engineered as a client–server application for which a single server or more rarely a small cluster of servers contain all the world pertinent data and assume the world accessibility, consistency and persistence. On the client side, many of them enable interaction with the other users and the various objects of the world. The main originality of our approach resides in the fact that the server part of the proposed system is no more limited to a few centralized servers, but can be distributed on arbitrarily many of them. Indeed, MaDViWorld, the prototypal software framework already implemented using Java and RMI by our group, allows for creating the rooms of a given world on several machines, each running the server application. It is then possible to connect the rooms by way of simple doors and to populate them with active objects. Finally, avatars managed by the client application visit the rooms and interact with the active objects either directly on the remote host or locally by cloning or transporting them first to the client machine. This paper draws from the experience gained with the development of our first prototype in order to discuss, both at the user's and the vi‐world developer's level, the main software engineering issues related to the implementation of such massively distributed virtual world systems. Copyright © 2002 John Wiley & Sons, Ltd.
Effects of acute “binge” cocaine on preprodynorphin, preproenkephalin, proopiomelanocortin, and corticotropin‐releasing hormone receptor mRNA levels in the striatum and hypothalamic–pituitary–adrenal axis of mu‐opioid receptor knockout mice
Authors: Zhou Yan , Spangler Rudolph , Schlussman Stefan D. , Yuferov Vadim P. , Sora Ichiro , Ho Ann , Uhl George R. , Kreek Mary Jeanne
Published: October 2002

Cocaine administration increases activity at dopamine receptors, increases preprodynorphin (ppDyn) gene expression in the caudate‐putamen (CPu), and activates the stress responsive hypothalamic–pituitary–adrenal (HPA) axis. To examine the hypothesis that mu‐opioid receptors (MOR) may play roles in these cocaine effects, we tested the effects of acute “binge” pattern cocaine administration in mice with targeted disruption of the MOR gene. Wild‐type (+/+) and homozygous MOR‐deficient (−/−) mice received three injections of 15 mg/kg cocaine at 1‐h intervals. Mice were sacrificed 30 min after the last injection and mRNAs for ppDyn and preproenkephalin (ppEnk) in the CPu and nucleus accumbens (NAc), and for type I corticotropin‐releasing hormone receptor (CRH1 receptor) and pro‐opiomelanocortin (POMC) in the hypothalamus and pituitary, were measured by solution hybridization RNase protection assays. Cocaine elevated ppDyn mRNA in the CPu, but not NAc, of both the MOR −/− and wild‐type mice. ppEnk mRNA in the CPu, but not NAc, was lower in MOR −/− mice than in wild‐type mice following cocaine administration. Hypothalamic CRH1 receptor and POMC mRNAs were expressed at similar levels in untreated and in cocaine‐treated mice of each genotype. However, there were lower basal levels of CRH1 receptor mRNA in the anterior pituitary of the MOR −/− mice than in wild‐type mice and the MOR −/− mice failed to show the cocaine‐induced decreases in CRH1 receptor mRNA found in the wild‐type mice. Cocaine activated the HPA axis similarly in MOR −/− and wild‐type mice, as reflected in similar increases in plasma corticosterone levels in both genotypes. These results support a specific role for MORs in acute cocaine effects on striatal ppEnk gene expression and fail to support critical roles for these receptors in acute cocaine's effects on either ppDyn gene expression or HPA activation. MOR −/− mice are useful models for studying cocaine effects on ppEnk gene expression that could aid interpretation of the similar postmortem phenomena found in human cocaine addicts. Synapse 45:220–229, 2002. © 2002 Wiley‐Liss, Inc.
Frozen‐sectioning yields similar results as traditional methods for fetal cephalic examination in the rat
Authors: Astroff A. Barry , Ray Sylvia E. , Rowe Leanna M. , Hilbish Kim G. , Linville Alisha L. , Stutz John P. , Breslin William J.
Published: October 2002

Background

An integral component of developmental toxicity studies is the evaluation of fetal anatomy, which consists of external, visceral, and skeletal examinations. The visceral examination includes an assessment of the fetal head which, in the rat, is typically completed after chemical fixation. Because chemical fixation requires approximately 7 days, a comprehensive visceral examination, including the head, of the fetal rodent cannot be completed at the time of cesarean section. An alternative method to chemical fixation was desired, whereby one could complete an overall visceral examination at the time of cesarean section. In addition, the method would also have to present fetal cranial structures in a manner consistent with that derived after chemical fixation.

Methods

Pregnant Sprague–Dawley rats were administered either 6‐aminonicotinamide (6AN), 6 or 12 mg/kg on gestation day 13, or all‐trans retinoic acid (RA) 5 or 25 mg/kg on gestation days 9 and 10, untreated dams served as a control group. On gestation day 20, fetuses were sacrificed and removed via cesarean section and one‐half of the fetuses from each litter were placed in Bouin's solution (chemical fixation) and the remaining fetuses maintained under refrigeration until just before frozen tissue preparation (freeze fixation). Sectioning of the fetal head was similarly conducted after either chemical or frozen‐fixation. Fetal cranial findings observed after chemical fixation were compared to those observed after frozen‐fixation in the untreated control and 6AN and RA‐treated groups.

Results

The incidence and severity of the cranial findings, including effects on the eye, brain, and palate, were similarly observed, regardless of fixation method.

Conclusions

A frozen sectioning method for evaluation of the fetal head, yielding results comparable to those derived after chemical fixation, is described. This procedure provides a viable alternative to chemical fixation, and allows the teratologist to complete a comprehensive fetal visceral examination at the time of cesarean section. Teratology 66:77–84, 2002. © 2002 Wiley‐Liss, Inc.
Research note: Sales force opportunism in emerging markets: An exploratory investigation
Authors: Li Lee
Published: October 2002

Do overseas‐based sales forces commit opportunism? Answer to the question is critical for exporting

manufacturers who are considering setting up sales offices in emerging markets. This inductive study of 15 British

manufacturers in China led to propositions exploring the question. It specifies various contexts in which sales

force employees in emerging markets may commit opportunistic behaviors. In those contexts, sales offices in emerging

markets may not necessarily combat channel opportunism or save monitoring costs. © 2002 Wiley Periodicals,

Inc.
An examination of key aerodynamic modelling issues raised by the NREL blind comparison
Authors: Coton Frank N. , Wang Tongguang , Galbraith Roderick A. McD.
Published: October 2002

In May 2000 the US National Renewable Energy Laboratories (NREL) invited the international community to provide aerodynamic calculations for a range of test cases on its Unsteady Aerodynamics Experiment (UAE) wind turbine. Prior to this, NREL had collected test data on the turbine for these same cases in the NASA Ames wind tunnel. The calculations were conducted in the blind, i.e. without knowledge of the measured data, and subsequently compared with the data. This article describes some recent work undertaken in the aftermath of this ‘Blind Comparison’. The data set collected in the NASA Ames tunnel represents a unique opportunity for aerodynamic modellers to enhance the capability of prediction schemes by comparison with ‘clean’ aerodynamic data. In this article the sensitivity of the results predicted by the Glasgow University prescribed wake model (HAWTDAWG) to a range of parameters is examined with reference to the measured data. The sensitivity of the calculations to the input blade section aerodynamic data is demonstrated. It is also shown that, despite differences in the measured and predicted results, the inclusion of a dynamic stall model generally improves the quality of predictions at large yaw angles even when the model is not optimized for wind turbine flows. Finally, it is shown that careful selection of appropriate tower shadow velocity deficits can result in predictions that agree well with the measured data in terms of the depth and duration of the response. Copyright © 2002 John Wiley & Sons, Ltd.
Incoherent scattering functions for some elements with 23 ≤ Z ≤ 81
Authors: Yalçın P. , Kurucu Y. , Şahin Y.
Published: October 2002

Incoherent scattering functions were determined experimentally for a photon energy of 59.5 keV at an angle 110° for the elements V, Cr, Co Br, Sr, Cd, I, Cs, Ba, Ce, Nd, Sm, Hf, Os and Tl using a high‐resolution Ge(Li) detector. The experimental values of incoherent scattering functions at the momentum transfer x ≈ 2.74 Å−1 were compared with those estimated on the basis of the non‐relativistic Hartree–Fock wavefunctions. The present results were in good agreement with those of Hubbell et al. Copyright © 2002 John Wiley & Sons, Ltd.
Coherent and incoherent scattering of 17.44 and 6.93 keV x‐ray photons scattered from biological and biological‐equivalent samples: characterization of tissues
Authors: Poletti M. E. , Gonçalves O. D. , Mazzaro I.
Published: October 2002

The angular distribution of photons scattered by healthy (adipose and glandular) and cancerous human breast tissue and by tissue‐equivalent materials were measured for photon energies of 17.44 keV (Kα radiation of Mo) and 6.93 keV (Kα radiation of Co) using an x‐ray tube equipped with a graphite monochromator and a goniometer system. The measurements of 17.44 keV were performed in transmission geometry with an acceptance of ±0.3° and an uncertainty of ∼7%. The measurements at 6.93 keV were performed in reflection geometry with solid samples in order to detect crystal structures in the samples. All samples show scattering signatures similar to those of amorphous material, but some of them also present sharp peaks corresponding to crystalline structure. Strong differences between breast‐equivalent material and breast tissue occur at low and medium scattering angles. Healthy and cancerous breast tissue show considerable differences. The results demonstrate that x‐ray scattering signatures (coherent and incoherent) are good parameters for characterizing breast tissue. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of Coster–Kronig transition probabilities (L1 → L2, L1 → L3 and L2 → L3) for Hg and Bi in molecules
Authors: Söǧüt Ömer , Büyükkasap Erdoǧan , Küçükönder Adnan , Ertuǧrul Mehmet , Erdoǧan Hasan
Published: October 2002

The f12, f13 and f23 Coster–Kronig (CK) transitions (that is L1 → L2, L1 → L3 and L2 → L3 transitions) in Hg and Bi in molecules were studied at 59.5 keV excitation energy using an Si(Li) detector. A change in the CK transition probabilities was observed for different molecules. The change in the values for Hg compounds were greater than those for Bi compounds. Because we did not have pure Bi in the laboratory and also were not able to have specimen preparation conditions for pure Hg, we did not obtain experimental values for elemental Bi and Hg. Copyright © 2002 John Wiley & Sons, Ltd.
Nutrient intake and apparent digestibility of diets consumed by captive duikers at the Dambari Field Station, Zimbabwe
Authors: Plowman Amy B.
Published: October 2002

The nutrient intake and apparent digestibility of two diets fed to seven species of captive duikers at the Dambari Field Station, Zimbabwe, were examined. The original diet consisted of pellets, mixed grain, and fruit (approximately 11% protein, 21% NDF) and the revised diet of pellets and vegetables (approximately 14% protein, 31% NDF). The revised diet resulted in an increased intake of protein and fiber, and a reduced intake of nonstructural carbohydrate and fat, and was therefore more comparable to the natural diets of duikers. The revised diet also resulted in an increased intake of most minerals (except sodium). Total dry‐matter intake increased on the revised diet, but estimated digestible energy decreased. The revised diet was intended to provide 75% of calories from the pellets, but in fact the revised diet as consumed resulted in 85% of calories being derived from pellets. Achievement of the lower number is recommended to decrease the intake of iron and copper. Fecal quantity was significantly greater, and apparent digestibility of dry matter, protein, NDF, and ADF significantly less for all species on the revised diet compared with the original. Apparent digestibility of fiber by red duikers was comparable to that of common duikers, and was affected similarly by the diet change. However, it was less comparable to that of blue and yellow‐backed duikers, suggesting that the diet of free‐ranging red duikers may be more similar to that of common duikers than to that of the other forest duikers. Zoo Biol 21:135–147, 2002. © 2002 Wiley‐Liss, Inc.
Changes in the concentration of ions during senescence of the human erythrocyte.
Authors: Cameron Ivan L. , Hardman W. Elaine , Smith Nancy K. R. , Fullerton Gary D. , Miseta Attila
Published: October 2002

Flash frozen samples of normal human blood were cryosectioned and cryodried for electron probe x‐ray microanalysis of the concentration of ions and elements in individual erythrocytes (RBCs). The data (expressed in mM/kg dry weight) demonstrated a systematic pattern of variation between the concentration of ions and elements in the RBCs. Specifically as K+ and Cl decreased in concentration, Ca2+ and sulfur increased in concentration. Phosphorous, Na+ and Mg2+ did not demonstrate a significant pattern of change. These findings are related to the dehydration and to the volume decrease that accompanies senescence of the RBC.
Differential expression of adult type MHC in satellite cell cultures from regenerating fast and slow rat muscles.
Authors: Cantini Marcello , Fiorini Emma , Catani Claudia , Carraro Ugo
Published: October 2002

The local anaesthetic (Bupivacaine (1‐n‐butyl‐DL‐piperidine‐2‐carboxylic acid‐2, 6‐dimethyl anilide hydrochloride) has been used to induce myofiber damage (and thus satellite cells proliferation) and thereby represents a tool for increasing the yield of myoblasts from adult muscles. Replicating satellite cells were isolated by enzymatic dissociation from soleus (slow type) and tibialis anterior (fast type) muscles of adult rats, and categorized by the isoform (embryonic, fast and slow) of myosin heavy chain (MHC) expressed following myotube formation in a similar in vitro environment. According to light microscopic criteria, no morphological differences exist between the satellite cell cultures obtained from adult fast and slow muscles after Bupivacaine injection. On the other hand the derived myotubes express, beside the embryonic type, the peculiar myosin heavy chains which characterize the myosin pattern of the donor muscles.
Effect of enthidium on the morphology, antiviral activity and subcellular distribution of Poly r(A‐U)
Authors: Jamison James M. , Gilloteaux Jacques , Adrian Marc , Summers Jack L.
Published: October 2002

When ethidium bromide (EB) is combined with poly r(A‐U) at an EB/ribonucleotide ratio of 1/4, the antiviral activity of the EB increases 22‐fold. The increased antiviral activity is not due to increased interferon induction, direct viral inactivation or host cell cytotoxicity. Phase contrast, confocal and fluorescence microscopic observations reveal an increase in the nucleolar accumulation of the EB and/or the poly r(A‐U) in the EB/poly r(A‐U)‐treated fibroblasts. Ultrastructure of negatively stained and replica preparations demonstrated that EB‐induced condensation of poly r(A‐U). These results suggest the elevated antiviral activity may be related to the altered uptake and subcellular distribution of the EB/poly r(A‐U) complex.
The prominent 28 kDa polypeptide in clathrin coated vesicle fractions from developing pea cotyledons is contaminating ferritin
Authors: Hoh Birgit , Robinson David G.
Published: October 2002

SDS‐PAGE of clathrin coated vesicle (CCV) fractions prepared from developing pea cotyledons are characterized by the presence of a 28 kDa polypeptide. Like clathrin light chains, this polypeptide is heat‐stable and can bind calcium ions. However, the distribution of this polypeptide is not identical to that of clathrin in the rate zonal gradients used to purify CCV. Negatively stained preparations reveal small, 12 nm diameter hollow particles, in addition to CCV. As judged by the electron dense centre to these particles, we infer that CCV preparations from pea cotyledons are contaminated with phytoferritin. This has been confirmed by immuno‐blotting with pea ferritin antibodies. The degree of phytoferritin contamination in CCV fractions is greater when RNase digestion of postmicrosomal pellets is performed at cold, rather than warm temperatures.
Transfected Chinese hamster ovary cells as a model system for cytokine immunocytochemistry and in situ hybridisation.
Authors: Mueller Regula , Junker Udo , Wagner Kathrin , Heusser Christoph , Bullock Gillian
Published: October 2002

The presence of cytokine producing cells is most easily revealed by techniques measuring the secreted cytokines in culture supernatants or body fluids. However, these techniques only measure the bulk cytokine release by a given, often mixed cell population. To demonstrate cytokine production at the single cell level, immunocytochemistry (ICC) and in situ hybridisation (ISH) are now widely used techniques. To establish these techniques, an easily accessible model system is needed which permits the evaluation of different ICC and ISH protocols. It can be used to demonstrate the specificity of the antibodies and may serve as a positive control for samples of unknown cytokine content. Here we propose the use of Chinese hamster ovary (CHO) cells transfected to express one specific cytokine as such a model system. Its usefulness is demonstrated by the characterisation of six monoclonal antibodies to human interleukin‐4 and the establishment of two in situ hybridisation protocols.
VLA‐2 mediates the interaction of collagen with endothelium during in vitro vascular tube formation.
Authors: Jackson Christopher J. , Knop Alison , Giles Irina , Jenkins Kate , Schrieber Les
Published: October 2002

A confluent endothelial monolayer can be induced to form vascular tubes in response to collagen. We investigated possible mechanisms of collagen‐induced tube formation by using antibodies to the VLA‐2 integrin receptor and protein kinase C inhibitors. Pre‐incubation of cells with anti‐VLA‐2 (which recognises both the α2 and β1 chains) and AK7 (which recognises only the α2 chain) showed a dose‐dependent inhibition of tube formation. At 50 μg/ml, anti‐VLA‐2 completely inhibited collagen‐induced tube formation, whereas AK7 caused only partial inhibition. Both chlorpromazine and trifluoperazine, at concentrations of 10μM, prevented tube formation (> 40% inhibition), In summary, the VLA‐2 integrin receptor plays a role in the induction of tube formation by type I collagen. Protein kinase C may be activated during this process.
The induction of protrusion by neomycin in human glioma cells is correlated with a decrease followed by an increase in filamentous actin.
Authors: Safiejko‐Mroczka Barbara , Bell Paul B.
Published: October 2002

In this paper we describe an experimental investigation of the mechanism of motility of vertebrate cells. Human glioma cells were treated with neomycin, an inhibitor of the phosphatidylinositol cycle; and changes in cell motility and the cytoskeleton were examined by video, fluorescence, and scanning electron microscopy and by cytofluorometry. Neomycin stimulates a single protrusion of lamellipodia from the cell margin, which is correlated with an initial rapid decrease in the amount of F‐actin throughout the cell, especially at the cell edge; the fragmentation of actin filaments within the lamellipodia; and the subsequent de novo polymerization of F‐actin in a marginal band at the leading edge of lamellipodia. Changes in F‐actin are paralleled by changes in the distribution and amount of gelsolin. These results support the hypothesis that protrusion is initiated by the gelsolin‐mediated severing and subsequent depolymerization of cortical actin filaments, which weakens the cell cortex, allowing hydrostatic or gel osmotic pressure to force the cell margin to protrude. The accompanying polymerization of filaments actin at the leading edge of the protrusion may stabilize the protrusion and support its expansion.
THE ROLE OF CDC2, CDC25 AND CYCLIN A GENES IN THE MAINTENANCE OF IMMORTALIZATION AND GROWTH ARREST IN A RAT EMBRYONIC FIBROBLAST CONDITIONAL CELL LINE
Authors: GONOS EFSTATHIOS S. , SPANDIDOS DEMETRIOS A.
Published: October 2002

Immortalization of rodent cells by oncogenes is a complex biological process which involves the abnormal regulation of genes who control cellular proliferation. The role of the cell cycle control genes cdc2, cdc25 and cyclin A in the maintenance of immortalization and in growth arrest was examined in the tsa14, a SV40 T antigen rat embryonic fibroblast conditional for growth cell line. Analysis of RNA expression showed minimal levels of cdc2 mRNA in both proliferating and growth‐arrested tsa14 cells. In contrast, cyclin A mRNA was found downregulated in growth‐arrested tsa14 cells, as well as in senescent primary rat embryonic fibroblasts (REFS). The ability of cdc2, or cdc25, or cyclin A genes to maintain the tsa14 immortal phenotype was also examined by electroporations of these genes into the tsa14 cells. Clones over‐expressing the electroporated cdc2, or cdc25, or cyclin A, or combinations of these genes growth arrested at the non‐permissive conditions similar to controls, thereby suggesting that the expression of these genes alone is insufficient for tsa14 maintenance of immortalization.
DIGITAL IMAGE ANALYSIS OF CHROMATIN FIBRE PHENOTYPE AFTER ‘IN SITU’ DIGESTION WITH RESTRICTION ENDONUCLEASES
Authors: GOSÁLVEZ JAIME , LÓPEZ‐FERNÁNDEZ CARMEN , FERNÁNDEZ JOSÉ L. , GOYANES VICENTE J. , BUÑO ISMAEL
Published: October 2002

Restriction Endonucleases (REs) may recognize, cleave and remove DNA from fixed chromatin producing specific chromosome banding patterns. However, the modifications produced in the chromatin fibre are not easy to evaluate and compare. The aim of the present investigation was to visualize differences resulting in the texture of the chromatin fibre from metaphase chromosomes after each digestion using digital image analysis (DIA) facilities. To this purpose, metaphase chromosomes derived from a L‐929 mouse cell line were digested with different REs (AluI,HpaII andHaeIII).

Since light microscopy does not permit the observation of the chromatin fibre, DIA was performed on digitalized images of metaphase chromosomes under electron microscopy. The application of a LUT (Look Up Table) within the DIA software assigns a colour to each grey level of a digital image. The results obtained using a particular LUT, which permits the discrimination of specific chromatin fibre phenotypes resulting from each digestion, are reported and compared with those obtained under the light microscope.
STUDIES ON NITRIC OXIDE FREE RADICALS GENERATED FROM POLYMORPHONUCLEAR LEUKOCYTES (PMN) STIMULATED BY PHORBOL MYRISTATE ACETATE (PMA)
Authors: ZHAO BAO‐LU , WANG JIAN‐CHAO , HOU JING‐WU , XIN WEN‐JUAN
Published: October 2002

The interaction of NO and O−2free radicals generated from PMA (phorbol myristate acetate)‐stimulated PMN (polymorphonuclear leukocytes) was studied by a nitroxide spin trap, DMPO (5,5‐dimethyl‐1‐pyrroline‐1‐oxide). It was found that addition of L‐arginine to the system would significantly decrease the trapped O−2by DMPO and addition of NG‐monomethyl‐arginine (NGMA) would significantly increase the trapped O−2by DMPO. It was proved that the formation of ONOO−by the reaction of NO and O−2was the main reason for the decrease of trapped O−2in the experiment with xanthine/xanthine oxidase and irradiation of riboflavin systems. The yield of NO during this process was calculated. The generation dynamic of NO was studied by a luminol‐dependent chemiluminescence technique and it was found that after stimulation of PMN by PMA, there would be an immediate, significant chemi‐luminescence, which came mainly from the active oxygen free radicals generated by PMN. If L‐arginine was added to this system, the chemiluminescence would increase about 100‐fold, but NGMA inhibited the increase of the chemiluminescence. Ten minutes after addition of L‐arginine, this increase did not change, the chemiluminescence peak decreased gradually, but the half life increased. The ESR and chemiluminescence properties of NO and ONOO−synthesized were also studied in model systems.
ENHANCEMENT OF 5‐FLUOROURACIL CYTOTOXICITY BY CISPLATIN IN BRAIN TUMOUR CELL LINES
Authors: MINEURA KATSUYOSHI , KOWADA MASAYOSHI
Published: October 2002

Cisplatin reportedly plays an important role as a chemical modulator in enhancing the chemotherapeutic effects of 5‐fluorouracil on tumour cells. The aim of the present study was to test the synergistic cytotoxicity of cisplatin and 5‐fluorouracil in 5‐fluorouracil‐resistant (C6) and ‐sensitive (9L) rat brain tumour cell lines. Survival fractions, determined using colony‐formation assays, were compared following 5‐fluorouracil treatment, with and without cisplatin. The presence of cisplatin (1–10μm) enhanced cytotoxicity by more than three times compared with 5‐fluorouracil alone in 5‐fluorouracil‐resistant C6 cells, whereas no enhancement effects were noted in 9L cells. These results suggest that a cisplatin‐fluorouracil‐based regimen may be promising in the treatment of 5‐fluorouracil‐resistant brain tumours.
CHARACTERIZATION OF FORCED SUSPENSION CULTURE OF SPONTANEOUSLY TRANSFORMED MOUSE FIBROBLASTS (B‐6)
Authors: MATSUHISA TADAO , TAKEMURA KOUICHI
Published: October 2002

Mouse fibroblasts (B‐6) were cultured on agar‐coated dishes. After cells grew for 2–3 generations relatively rapidly in suspension, they began to grow very slowly (stationary phase). Electron microscopic studies showed that cells in a stationary phase developed intracellular organella: membranous structures (endoplasmic reticulum and Golgi apparatus) became manifest and the number of mitochondria increased. The specific activities of succinic‐cytochrome c reductase and 5′‐nucleotidase were three and five times higher, respectively, than those of cells on the dish.
CELL SURFACE ALTERATIONS BY TAXOL ASSOCIATED WITH ABNORMAL MORPHOGENESIS IN THE CHICK EMBRYO
Authors: PATWARDHAN VIDYA , GHATE H. V. , GHASKADBI SURENDRA
Published: October 2002

The anticancer drug taxol brings about its biological effects by altering the stability of microtubules. We have examined the effects of taxol on early morphogenesis in chick embryos culturedin vitro. Taxol induced various abnormalities in the developing nervous system, heart and somites as well as general retardation of development. SEM studies revealed that taxol treatment leads to dramatic alterations in the embryonic cell surfaces. Time‐course experiments demonstrated that the action of taxol is very rapid and becomes evident within a few minutes at the ultrastructural level. Taxol thus throws embryonic cell adhesion and motility out of balance. This appears to be the major cause of abnormal morphogenesis in taxol‐treated embryos.
ISOLATION OF CYTOCHROME OXIDASE COMPLEX FROM SEA URCHIN MITOCHONDRIAL INNER MEMBRANES
Authors: KUTRA TEOFANI , TIMONERI MARINA , OLIVA ANTONINO , RINALDI ANNA MARIA
Published: October 2002

Cytochrome oxidase complex has been isolated and purified from sea urchin mitochondrial inner membranes. The complex exhibited a discrete number of bands in PAGE and a 17 kDa band was recognized by an anti‐human subunit IV antibody. No bands were recognized by an anti‐yeast hsp60 antibody and an anti‐sea urchin β ATPase subunit.
IMMUNOHISTOCHEMICAL LOCALIZATION OF TYPE I AND II COLLAGENS IN THE INVOLUTING CHICK NOTOCHORDS IN VIVO AND IN VITRO
Authors: GHANEM E.
Published: October 2002

Embryonic chick notochords were studied during their metabolically active and involuting periods for the expression of collagen type I and II. The staining was carried out on notochords in vivo at stage 20 and stage 35 and on mesenchyme‐contaminated and mesenchyme‐free notochords at stage 20, which were cultured in vitro for 6 days. The results show that type II collagen is demonstrable in the notochords, at all the examined stages, both in vivo and in vitro. However, the expression of type I collagen was stage‐dependent in vivo and in vitro. At stage 20, the perinotochordal sheath is positively immunostained for collagen type I, but the notochord itself is negative. At stage 35, the perinotochordal sheath as well as the notochord are positively immunostained for collagen type I. The mesenchyme‐contaminated and the mesenchyme‐free notochords and their sheaths are also positively immunostained for the type I collagen after6 days in vitro. The current results, at late developmental stages, indicate that the involuting notochords express collagen type I, which seems not to be altered by changing the micro‐environment in vivo.
THE DISTINCT STEPS OF CELL DETACHMENT DURING DEVELOPMENT OF MOUSE UROEPITHELIAL CELLS IN THE BLADDER
Authors: JEZERNIK K. , STERLE M. , BATISTA U.
Published: October 2002

In developing mouse urinary bladder the urothelial cells respond to urine accumulation by cell detachment, i.e. desquamation. To elucidate the steps of urothelial cell detachment during embryonic development and first urine accumulation in bladder lumen, superficial and intermediate cell layers were investigated. Different electron microscopic and cytochemical methods have been used. It was possible to distinguish between an early and late events on the basis of morphology. At the beginning cell detachment involves interruption of tight junctions between neighbouring superficial cells and the formation of numerous endocytotic vesicles. Endocytotic and cup‐shaped vesicles then fuse and form large parallel rows of vacuoles and multivesicular bodies in desquamating superficial cells and in the neighbouring superficial and intermediate cells. These observations clearly demonstrate the existence of specific steps during the detachment of embryonic uroepithelial cells.

Apoptosis accompanies cell desquamation. Only predetermined superficial bridge cells die in an apoptotic manner.
INTRANUCLEAR NETWORK OF 3–5nm AND 8–10nm FIBERS IN EL‐4 LYMPHOMA CELLS
Authors: PADROS MARIA R. , GILES DEBRA M. , SUAREZ MARIA D.
Published: October 2002

While much evidence indicates a high degree of spatial organization in the nucleus, the underlying molecular structures that support it remain poorly characterized. By extracting with high concentrations of RNase A in a modification of the sequential extraction protocol of Penman, we have identified a novel intranuclear network in the mouse lymphoma cell line, EL‐4. Micrographs of embedment‐free sections of extracted cells reveal anastomosing filaments of two different diameters: 3–5nm and 8–10nm. The 3–5‐nm filaments are interconnected in many junctions and appear to blend smoothly into each other. The 8–10‐nm fibers frequently split into two 3–5‐nm filaments. Some 3–5‐nm fibers appear to be connected at 90° angles with the 8–10‐nm fibers. All junctions are smooth with no apparent junction protein. Flow cytometric analysis of RNase A‐ (and DNase I‐) extracted nuclear matrices indicates that they do not contain significant amounts of protein that react with anti‐actin and anti‐vimentin monoclonal antibodies. Extraction of EL‐4 nuclear matrices with high salt does not reveal 8–10‐nm core filaments described after similar treatment of tumor cell lines of cervical and mammary origin. The novel characteristics of the core filaments in EL‐4 lymphoma cells may reflect cell‐type specificity of the nuclear matrix.
INHIBITION OF PHENOTYPE MODULATION, GROWTH, AND MIGRATION OF VASCULAR SMOOTH MUSCLE CELLS BY A GUANOSINE‐RICH 30‐MER PHOSPHOROTHIOATE OLIGODEOXYNUCLEOTIDE
Authors: GRAHAM L. D. , HAYWARD I. P. , FITZGERALD M. , WHITELOCK J. M. , BINGLEY J. A. , CAMPBELL J. H. , UNDERWOOD P. A.
Published: October 2002

The testing of a 30‐mer dG‐rich phosphorothioate oligodeoxynucleotide (LG4PS) for effects on the behaviour of vascular smooth muscle cells (VSMC)in vitroandin vivois described. LG4PS at 0.3μminhibited significantly the phenotype modulation of freshly isolated rabbit VSMC, and cell outgrowth from pig aortic explants was inhibited ∼80% by 5μmLG4PS. The growth of proliferating rabbit and pig VSMC was inhibited ∼70% by 0.3μmand 5μmLG4PS, respectively. Though less marked, the antiproliferative effects of LG4PS on human VSMC were comparable to those obtained with heparin. The cytotoxic effects of LG4PS on VSMCin vitrowere low. Despite these promising results, adventitial application of 2–200nmol LG4PS in pluronic gel failed to reduce vascular hyperplasia in balloon‐injured rabbit carotid arteries, and the highest dose caused extensive mortality.
EFFECT OF SUBLETHAL DOSES OF CADMIUM, INORGANIC MERCURY AND METHYLMERCURY ON THE CELL MORPHOLOGY OF AN INSECT CELL LINE (AEDES ALBOPICTUS, C6/36)
Authors: BRAECKMAN BART , SIMOENS CAROLINE , RZEZNIK URSZULA , RAES HILDA
Published: October 2002

The effect of CdCl2(44μm), HgCl2(3.7μm), and MeHgCl (2μm) on the morphology ofAedes albopictusC6/36 cells was studied at the light microscopical level. Treatment times and metal concentrations were in the sublethal range as determined by a fluorometric dye exclusion test. The three metal species had profound effects on the cell morphology. MeHgCl treatment induced the development of a large number of short, actin‐supported, tangled filopodia. Both CdCl2and HgCl2induced long extensions. Pretreatment with colchicine but not with cyto‐chalasin B prevented formation of these extensions which suggests that they were supported by microtubules. This was confirmed by immunostaining for microtubules. The extensions were relatively stable towards colchicine post‐treatment. To authors’ knowledge, this effect has not yet been described for heavy metals. The similarity with 20‐hydroxyecdysone‐treated cells and the occurrence of cytoplasmic feet in insect cells is discussed.
OESTRADIOL REGULATED PROGRAMMED CELL DEATH IN RAT VAGINA: TERMINAL DIFFERENTIATION OR APOPTOSIS?
Authors: RAO K. SRIDHAR , ZANOTTI S. , REDDY A. G. , RAUCH F. , MANNHERZ H. G. , GUPTA P. D.
Published: October 2002

Rat vaginal epithelial cells (VEC) undergo division and differentiation under the influence of oestradiol in a programmed manner. The differentiation process of VEC leads to keratinization, cornification and subsequent desquamation of the dead cells. This process of programmed cell death, referred to as terminal differentiation may share some common pathways with cell death by apoptosis but differ substantially in many aspects. Terminal differentiation of VEC is accompanied by the loss of majority of the organelles including the nucleus. To understand the mechanisms that underlie this process we have analysed the regulation of DNase I (a key effector of apoptotic cell death) in rat VEC under the influence of oestradiol. The present study demonstrates that under physiological conditions, cell death in the VEC is mainly through terminal differentiation although a few cells may undergo apoptotic death involving DNA fragmentation. Unaltered levels of bcl‐2 message upon oestradiol administration suggest an important role played by this molecule in preventing death of the VEC by apoptosis.
A MULTICOPY c‐myc TRANSGENE AS A NUCLEAR LABEL: OVERGROWTH OF Myctg50CELLS IN ALLOPHENIC MICE
Authors: AUGUSTIN MARTIN , KLOPP NORMAN , EWALD KAI , JOCKUSCH HARALD
Published: October 2002

To trace cell lineages and the origin and fate of cells in transplantation and embryo chimeras, a DNA/DNA in situ hybridization cell labelling system was developed, based on a 50‐copy murine c‐myc transgene on mouse chromosome 8. Elevated levels of cMyc mRNA were found in Myc*tg50 (Myctg50/0 and Myctg50/Myctg50) transgenic tissues, but adult transgenic NMRI mice were anatomically and histologically indistinguishable from control NMRI mice and did not develop tumours on a wild‐type or nude (nu / nu) background. The hybridization label detected transgenic nuclei with an efficiency of ∼80%. In muscle grafts, this transgene label was successfully applied to trace donor cells in a labelled host and to study the invasion of a graft by host cells. When the cMyc hybridization was used in allophenic mice of the control|acNMRI‐Myctg50/? (nu /+ or +/+) type, an up to a three‐fold excess of MYC*tg50 positive over control nuclei was found in all organs examined (ventricle, skeletal muscle, liver, small intestine). This overgrowth of MYC*tg50 cells is probably due to transgene expression. Four out of seven (C57BL/6×BALB/c) or (C57BL/6×NMRI)|acMYC*tg50 allophenic mice displayed anatomical abnormalities, e.g. an enlarged thymus and a tumour in the groin region. As these abnormalities were only observed in allophenic mice, they might be due to the imbalance of growth potential between MYC*tg50 transgenic and normal cells in the same individual.
PRESENCE AND LOCALIZATION OF HISTIDINE DECARBOXYLASE ENZYME (HDC) AND HISTAMINE IN TETRAHYMENA PYRIFORMIS
Authors: HEGYESI HARGITA , KOVÁCS PÉTER , FALUS ANDRÁS , CSABA GYÖRGY
Published: October 2002

Histidine decarboxylase (HDC) enzyme and its function under hormonal influences were studied in a low level of phylogeny. HDC protein is present in the unicellular ciliate Tetrahymena and its expression was not altered by insulin or histamine treatment. Starvation for 24h enormously decreased the quantity of histamine in the cells. However, insulin influenced the activity of the HDC enzyme, demonstrated by the seven‐fold quantity of histamine in the starved cells after insulin treatment. Insulin also increased the uptake of histamine from the tryptone‐yeast extract medium. HDC was found in different parts of the cytoplasm, mainly in the periphery (epiplasm) of the cells. The experiments demonstrated the uptake and synthesis of histamine by Tetrahymena as well as the possibility of hormonal regulation of HDC activity.
ALTERATIONS IN GLYCOSYLTRANSFERASES DURING MYELOID AND MONOCYTOID DIFFERENTIATION OF HL‐60 CELLS
Authors: LIU AI HUA , LIU FEI , LI ZHONG , GU JIAN XING , CHEN HUI LI
Published: October 2002

HL‐60, a human promyelocytic leukemia cell line, can be differentiated to myeloid lineage by all‐ trans retinoic acid (ATRA), dimethylsulfoxide (DMSO) and n ‐butyric acid (n ‐BA), or to monocytoid(monocytic/macrophagic) lineage by phorbol‐12‐myristate‐13‐acetate (PMA) and ganglioside GM3. The activity alterations of N ‐acetylglucosaminyltransferase III and V (GnT‐III, GnT‐V) as well as α‐1,6‐fucosyl‐tranferase (α1,6 Fuc T) were studied during the differentiation of HL‐60 cells by the above‐mentioned five inducers using the fluorescence (PA)‐labeled glycan‐HPLC method for GnT assays and biotin‐labeled glycan‐LCA affinity chromatography combined with the HRP‐avidin colorimetric method for α1,6 Fuc T assay. It was observed that after 3 days, all three enzymes decreased in HL‐60 cells induced by 1μmol/l ATRA and 0.6mmol/l n‐BA, while GnT‐III and α1,6 Fuc T increased, but GnT‐V still decreased after induction by 1% DMSO. GnT‐V and α1,6 Fuc T declined, while GnT‐III was elevated after induction by 0.1μmol/l PMA for 3 days. In contrast, GnT‐III increased after the treatment with 50μmol/l GM3for 3 or 6 days, but GnT‐V was not appreciably changed and α1,6 FucT was elevated after 6 days of GM3treatment. It may be concluded that the decrease of GnT‐V is the common change in myeloid differentiation and the increase of GnT‐III is the general alteration in monocytoid differentiation. The changes in the activities of glycosyltransferases were consistent with the structural changes in surface N ‐glycans previously found in our laboratory, i.e. that the antennary number of N ‐glycans decreased during myeloid differentiation by ATRA, and the amount of bisecting GlcNAc in N ‐glycans increased during monocytoid differentiation by PMA.