bluuebunny/crossref_metadata_2025 huggingface dataset:
Parametric mapping of [18F]FPCIT binding in early stage Parkinson's disease: A PET study
Authors: Ma Y. , Dhawan V. , Mentis M. , Chaly T. , Spetsieris P.G. , Eidelberg D.
Published: October 2002

We have shown that fluorinated N‐3‐fluoropropyl‐2‐beta‐carboxymethoxy‐3‐beta‐(4‐iodophenyl) nortropane ([18F]FPCIT) and PET offer a valuable means of quantifying regional abnormality in dopamine transporter (DAT) imaging associated with Parkinson's disease (PD). The objective of this study was to delineate the topographic distribution of DAT binding in early stage idiopathic PD using statistical parametric analysis of [18F]FPCIT PET data. We performed dynamic PET studies in 15 hemi‐parkinsonian (Hoehn & Yahr I) patients and 10 age‐matched normal volunteers over 100 min and calculated images of [18F]FPCIT binding ratios on a pixel‐by‐pixel basis. Statistical parametric mapping (SPM) was then used to localize binding reductions in PD and to compute the absolute change relative to normal. [18F]FPCIT binding decreased significantly in the contralateral posterior putamen of the PD group (P < 0.001, corrected). A significant reduction was also seen in the ipsilateral putamen, which was smaller in extent but localized more posteriorly. A quantitative comparison of DAT binding in the two clusters showed that the onset of motor symptoms in PD was associated with an approximate 70% loss relative to the normal mean in the contralateral posterior putamen. These results suggest that SPM analysis of [18F]FPCIT PET data can be used to quantify and map abnormalities in DAT activity within the human striatum. This method provides a useful tool to track the onset and progression of PD at its earliest stages. Synapse 45:125–133, 2002. © 2002 Wiley‐Liss, Inc.
Effect of glutamatergic systems on in vivo binding of [125I]β‐CIT in the brain of a rat model of Parkinson's disease
Authors: Kagawa Shinya , Nakano Takayuki , Inoue Osamu , Nishimura Tsunehiko
Published: October 2002

The effect of MK‐801, a noncompetitive NMDA receptor antagonist, on both in vivo and in vitro binding of [125I]β‐CIT (RTI‐55) was investigated in a rat model of Parkinson's disease. The binding experiments were performed 2 weeks after unilateral intranigral microinjection of 6‐hydroxydopamine (6‐OHDA). In the in vitro binding study, no alterations in [125I]β‐CIT binding in rat brain sections were observed after addition of MK‐801, 0.03 μM or 3 μM, to the incubation medium. However, in vivo [125I]β‐CIT binding to the dopamine transporter in both nonlesioned and 6‐OHDA‐lesioned striatum was significantly increased by pretreatment with MK‐801. In vivo [125I]β‐CIT binding to the serotonin (5HT) transporter in nonlesioned cerebral cortex, hypothalamus, and thalamus was also significantly increased by MK‐801. However, the degree of change in the specific binding of [125I]β‐CIT induced by MK‐801 was smaller in the lesioned cerebral cortex. Kinetic analysis, by a simplified three‐compartment model with the cerebellum as the reference region, revealed that these alterations in the in vivo [125I]β‐CIT binding induced by MK‐801 were mainly due to changes in the rate constants of in vivo binding, the input rate constant, k3, and the output rate constant, k4. These results indicate that the glutamatergic system significantly affects the function of dopamine transporters in the degenerated dopaminergic neurons in Parkinson's disease. Synapse 46:38–44, 2002. © 2002 Wiley‐Liss, Inc.
Synthesis of Aza‐Heterocycles from Oximes by Amino‐Heck Reaction
Authors: Kitamura Mitsuru , Narasaka Koichi
Published: October 2002

Oxidative addition of oximes to palladium(0) complexes generates alkylideneaminopalladium‘II’ species, which are utilized as key intermediates for carbon–nitrogen bond formation. Various aza‐heterocycles, such as pyrrole, pyridine, isoquinoline, spiroimine, and azaazulene, can be synthesized from O‐pentafluorobenzoyloximes having an olefinic moiety via an intramolecular Heck‐type reaction ‘amino‐Heck reaction’ by treatment with a catalytic amount of a Pd‘0’ complex. © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2: 268–277, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10030
Implementation of a peer‐led team learning instructional approach in an undergraduate organic chemistry course
Authors: Tien Lydia T. , Roth Vicki , Kampmeier J.A.
Published: October 2002

This study focuses on the implementation of a peer‐led team learning (PLTL) instructional approach for all students in an undergraduate organic chemistry course and the evaluation of student outcomes over 8 years. Students who experienced the student‐centered instruction and worked in small groups facilitated by a peer leader (treatment) in 1996–1999 were compared with students who experienced the traditional recitation section (control) in 1992–1994. Quantitative and qualitative data show statistically significant improvements in student performance, retention, and attitudes about the course. These findings suggest that using undergraduate leaders to implement a peer‐led team learning model that is built on a social constructivist foundation is a workable mechanism for effecting change in undergraduate science courses. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 606–632, 2002
Reluctance to use technology‐related products: Development of a technophobia scale
Authors: Sinkovics Rudolf R. , Stöttinger Barbara , Schlegelmilch Bodo B. , Ram Sundaresan
Published: October 2002

Many consumers feel overloaded by the complexity of technology‐related products. This renders

consumers less open to them and may even lead to an aversion or anxiety toward these kind of products: in other

words, so‐called technophobia.

This article aims to establish an instrument that measures technophobia. Following a literature review and

in‐depth interviews with experts, a scale is developed and tested in seven different countries

(United States, United Kingdom, France, Spain, India, Mexico, and Austria; total sample size =

1,503 respondents). The three underlying dimensions of the scale—“Personal Failure,”

“Human vs. Machine Ambiguity,” and “Convenience”—are discussed, and future

research avenues to strengthen the cross‐national usability of the scale are identified. © 2002

Wiley Periodicals, Inc.
A novel and sensitive test for rapid determination of water toxicity
Authors: Ulitzur S. , Lahav T. , Ulitzur N.
Published: October 2002

The performance of a novel, rapid, and sensitive test for detecting chemical toxicants in water is described in this article. The bioassay utilizes a highly sensitive variant of the luminescent bacterium Photobacterium leiognathi that allows the detection in water at levels below milligrams per liter of diverse groups of toxicants, including heavy metals, pesticides, PCBs, polycyclic aromatic hydrocarbons, and fuel traces. For most toxic agents reported in this study, the new assay was markedly more sensitive than the Microtox™ Vibrio fischeri assay according to the bacterial bioluminescence toxicity data reported in the literature. Additional features of the new bioassay include the ability to discriminate between cationic heavy metals and organic toxicants and the option of being run at ambient temperatures (18°C–27°C), thereby enabling on‐site testing with low‐cost luminometers. In addition, the stability of the freeze‐dried bacterial reagent preparation at ambient temperatures precludes the need for refrigeration or freezing during shipment, which contributes to further reducing overall operational costs. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 291–296, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10060
Effects of microcin SF608 and microcystin‐LR, two cyanotobacterial compounds produced by Microcystis sp., on aquatic organisms
Authors: Wiegand Claudia , Peuthert Anja , Pflugmacher Stephan , Carmeli Shmuel
Published: October 2002

Effects of two cyanobacterial compounds, microcin SF608 and microcystin‐LR, were investigated on different physiological parameters of two organisms, the water moss, Vesicularia dubyana, and the waterflea, Daphnia magna. Both compounds are produced by Microcystis species. Microcystin‐LR is a potent inhibitor of protein phosphatases 1 and 2A, and microcin SF608 inhibits serine proteases. Other effects of microcystin‐LR are well documented in the literature, but adverse effects of microcin SF608 have not been investigated as yet. This study compared the effects of both compounds on detoxication enzymes, microsomal and soluble glutathione‐S‐transferase (m‐, sGST); oxygen stress enzymes, glutathione peroxidase (GP‐X), and peroxidase (POD); photosynthetic oxygen production and chlorophyll a:chlorophyll b ratio. mGST was inhibited by both compounds in both organisms, significantly by microcin SF608, possibly indirectly by inhibition of that serine protease transforming the mGST to its active form. The sGST of D. magna was inhibited by microcin SF608, but elevated by microcystin‐LR, and elevated by both compounds in V. dubyana. The GP‐X in D. magna was not altered by microcin SF608, but elevated parallel to the sGST, whereas the POD in V. dubyana was decreased by both. Photosynthetic oxygen production as well as the chlorophyll a/b ratio showed typical stress reactions, a decrease of oxygen production, and an increase of chlorophyll b, caused both by microcin SF608 and by microcystin‐LR. Microcin SF608 was not likely to be detoxified via conjugation to glutathione. The effects of microcin SF608 and microcystin‐LR demonstrate that the impact of cyanobacteria on other organisms may not only be directly related to the presently known toxins. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 400–406, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10065
Advanced techniques for interactive visualization of multi‐resolution meshes
Authors: Grabner Markus
Published: October 2002

This paper addresses the problem of interactive visualization of multi‐resolution triangle meshes. Visible switching between different levels of detail is avoided by smoothly interpolating mesh geometry between different levels. The interpolation parameter is derived from the screen‐space geometric error of the affected mesh region instead of assigning a fixed time to the transition. The shortcomings of straightforward frame rate control mechanisms (i.e., overshooting and oscillation) are avoided by a semi‐predictive algorithm. The average rendering time per triangle is measured and used to determine the desired number of faces. A set of experiments demonstrates the advantages of both methods. Copyright © 2002 John Wiley & Sons, Ltd.
High‐quality texture reconstruction from multiple views
Authors: Bornik Alexander , Karner Konrad , Bauer Joachim , Leberl Franz , Mayer Heinz
Published: October 2002

This paper presents a method to automatically calculate texture maps for a given three‐dimensional object out of a sequence of images. It is used in our image‐based modeling approach after the registration of the images and the geometric modeling is done. We show that the presented method uses the information from all images by implicitly applying a weighting function. Using this approach the consideration of modeled occlusions as well as the detection and removal of non‐modeled occlusions is accomplished. The final resolution of the texture maps can be adjusted on a pixel/cm basis. Copyright © 2002 John Wiley & Sons, Ltd.
State‐of‐the‐art in orthopaedic surgical navigation with a focus on medical image modalities
Authors: Langlotz Frank
Published: October 2002

This paper presents a review of surgical navigation systems in orthopaedics and categorizes these systems according to the image modalities that are used for the visualization of surgical action. Medical images used to be an essential part of surgical education and documentation as well as diagnosis and operation planning over many years. With the recent introduction of navigation techniques in orthopaedic surgery, a new field of application has been opened. Today surgical navigation systems — also known as image‐guided surgery systems — are available for various applications in orthopaedic surgery. They visualize the position and orientation of surgical instruments as graphical overlays onto a medical image of the operated anatomy on a computer monitor. Preoperative image data such as computed tomography scans or intraoperatively generated images (for example, ultrasonic, endoscopic or fluoroscopic images) are suitable for this purpose. A new category of medical images termed ‘surgeon‐defined anatomy’ has been developed that exclusively relies upon the usage of navigation technology. Points on the anatomy are digitized interactively by the surgeon and are used to build up an abstract geometrical model of the bony structures to be operated on. This technique may be used when no other image data is available or appropriate for a given application. Copyright © 2002 John Wiley & Sons, Ltd.
A study of profiled handoff for Diffserv‐based mobile nodes
Authors: Jaseemuddin Muhammad , Ahmed Zubairi Junaid , Mahmoud Omer
Published: October 2002

There is a growing interest in providing Internet services to the mobile nodes. When mobile nodes travel from one router's service area to another, the time‐sensitive applications may see degradation in service. We investigate into the effects of handoff on service quality of mobile nodes. Several experiments are conducted using various packet metering and marking schemes with or without transferring profiles to the new router. Results indicate the relative instability period following handoff, loss of packets and delay encountered by packets in profiled or un‐profiled handoffs, leading to determining suitable mix of metering and marking schemes with or without context transfer. Copyright © 2002 John Wiley & Sons, Ltd.
Challenges in modelling the unsteady aerodynamics of wind turbines
Authors: Leishman J. Gordon
Published: October 2002

Many of the aerodynamic phenomena contributing to the observed effects on wind turbines are now known, but the details of the flow are still poorly understood and are challenging to predict accurately. This article emphasizes two key areas that need continued serious consideration for wind turbine predictive analyses: the modelling of the rotor wake and the modelling of the unsteady aerodynamics of the blade sections. Issues discussed herein include the modelling of the induced velocity field produced by the vortical wake behind the turbine, the various unsteady aerodynamic issues associated with the blade sections, and the non‐linear intricacies of dynamic stall. Fundamental limits exist in the capabilities of all models, and ambiguities can also arise in how these models should be properly applied. A challenge for analysts of the future is to use complementary experimental measurements and modelling techniques to better understand the aerodynamic problems found on wind turbines, and to develop more rigorous models with wider ranges of application. Copyright © 2002 John Wiley & Sons, Ltd.
Stop codon decoding in Candida albicans: from non‐standard back to standard
Authors: Moura Gabriela , Miranda Isabel , Cheesman Caroline , Tuite Mick F. , Santos Manuel A. S.
Published: October 2002

The human pathogen Candida albicans translates the standard leucine‐CUG codon as serine. This genetic code change is mediated by a novel ser‐tRNACAG, which induces aberrant mRNA decoding in vitro, resulting in retardation of the electrophoretic mobility of the polypeptides synthesized in its presence. These non‐standard decoding events have been attributed to readthrough of the UAG and UGA stop codons encoded by the Brome Mosaic Virus RNA 4, which codes for the virion coat protein, and the rabbit globin mRNAs, respectively. In order to fully elucidate the behaviour of the C. albicans ser‐tRNACAG towards stop codons, we have used other cell‐free translation systems and reporter genes. However, the reporter systems used encode several CUG codons, making it impossible to distinguish whether the slow migration of the polypeptides is caused by the replacement of leucines by serines at the CUG codons, readthrough, or a combination of both. Therefore, we have constructed new reporter systems lacking CUG codons and have used them to demonstrate that aberrant mRNA decoding in vitro is not a result from stop codon readthrough or any other non‐standard translational event. Our data show that a single leucine to serine replacement at only one of the four CUG codons encoded by the BMV RNA‐4 gene is responsible for the aberrant migration of the BMV coat protein on SDS–PAGE, suggesting that this amino acid substitution (ser for leu) significantly alters the structure of the virion coat protein. The data therefore show that the only aberrant event mediated by the ser‐tRNACAG is decoding of the leu‐CUG codon as serine. Copyright © 2002 John Wiley & Sons, Ltd.
A new insight into the suggestion of a possible antigenic role of a member of the 70 kD heat shock proteins.
Authors: Rocchi G. , Pavesi A. , Ferrari C. , Bolchi A. , Manara G. C.
Published: October 2002

In the present study the cellular distribution of the inducible (hsp72) and constitutive (hsc73) forms of human 70 kD heat shock protein was evaluated. A weak reactivity of the anti‐hsp72/hsc73 MoAb was found in the cytoplasm of the unstressed human epidermal cells, while stressed cells showed an enhanced reactivity at the cytoplasmic level and the expression of the molecules on the cell surface. Moreover, the antigenic properties of the two proteins were investigated by sequence analysis. Our findings provided evidence for at least three regions in the hsp72 which can be considered good candidates to represent T‐immunogenic antigens. This data as well as the cell surface localization of the hsp72 could suggest an antigenic role of the hsp72.
Phosphorylation pattern of liver proteins during the early stages of the acute‐phase response.
Authors: Piccoletti Roberta , Bendinelli Paola , Arienti Danilo , Maroni Paola , Bernelli‐Zazzera Aldo
Published: October 2002

Liver preparations from turpentine‐treated rats show an increased capacity to autophosphorylate a protein of 32.5 kDa (p 32.5): both the kinase and the substrate protein are strongly bound to the membrane fraction, but the protein is released to the cytosol after phosphorylation, which occurs exclusively in serine residues. No known second messenger‐dependent protein kinase seems to be responsible for the reaction. Phosphorylation of p 32.5 could be an early post‐receptorial event after turpentine‐treatment possibly caused by cytokines and involved in the pathogenesis of further events of the acute‐phase response.
Differential sensitivity of human hepatoma cell line and primary rat hepatocyte culture to benzo(a)pyrene‐induced unscheduled DNA synthesis and adduct formation.
Authors: Liu Tsung‐Yun , Chao Tsurn‐Waan , Chiang Su‐Hua , Chi Chin‐Wen
Published: October 2002

We studied the genotoxic potential of a carcinogen in the human hepatoma cell line, HepG2 and in primary rat hepatocyte culture. HepG2 is a well differentiated human hepatoblastoma cell line with biotransforming capacity. Rat hepatocytes were obtained by the standard two‐step in situ perfusion technique. Following benzo(a)pyrene treatment, both HepG2 and primary rat hepatocyte culture showed unscheduled DNA synthesis with different sensitivity. In 32P‐postlabelling analysis, the chromatogram revealed quantitative and qualitative differences between HepG2 and primary rat hepatocyte cultures when treated with 10 μM benzo(a)pyrene for 18 hr. The results have demonstrated that the HepG2 cell line may be used in addition to primary rat hepatocytes in risk assessment for detection of environmental carcinogens.
Effect of silica on the spontaneous cytotoxicity of axial organ cells from Asterias rubens.
Authors: Leclerc M. , Bajelan M. , Barot R. , Tlaskalova‐Hogenova H.
Published: October 2002

Axial organ cells (A.O.) which are composed of phagocytes and lymphocytes from the sea star Asterias rubens exert a spontaneous cytotoxicity against mouse tumour cells. This toxicity was tested in the presence or absence of silica. It appears that phagocytes play the role of killer cells.
Effect of extracellular matrix proteins on vascular smooth muscle cell phenotype
Authors: Hayward I. P. , Bridle K. R. , Campbell G. R. , Underwood P. A. , Campbell J. H.
Published: October 2002

The effect on phenotypic expression of rabbit vascular smooth muscle cells (SMC) of the interstitial matrix proteins collagen I and fibronectin, the basal lamina proteins collagen IV and laminin, and the serum adhesion protein vitronectin was examined in culture. Experiments were performed in foetal calf serum stripped of fibronectin and vitronectin to eliminate their confounding effects. All the proteins promoted adhesion to the plastic culture dish (in a concentration dependent manner) of SMC freshly isolated from the artery wall. These cells had a high volume density of myofilaments (Vvmyo) in their cytoplasm. Laminin was best at maintaining SMC with a high Vvmyo (Vvmyo = 49.8%) followed by collagen IV (41.7%). Cells plated on vitronectin showed the lowest Vvmyo (31.3%). The results support the concept that the SMC basal lamina has a role in maintaining cells in the high Vvmyo phenotype.
Maintenance of cytochrome P‐450 levels in hepatocytes preserved on gelatin gels
Authors: Evans Peter J.
Published: October 2002

In culture, cytochrome P‐450 levels fall rapidly with the result that hepatocytes are either used quickly or maintained in modified systems which prejudice their subsequent behaviour. In this study the effect of hypothermic preservation of hepatocytes on gelatin gels on levels of cytochrome P‐450 was investigated. In marked contrast to conventional cultures, hypothermic preservation (10°) maintained, over a 6‐day period, cytochrome P‐450 at levels similar to those of the more stable cytochrome b5. Cell storage on gelatin at 25° was associated with a conversion of cytochrome P‐450 to cytochrome P‐420. The procedure at 10° provides a valuable tool for toxicity testing, hepatocyte conservation and distribution.
Expression of α4 and β2 nicotinic acetylcholine receptor subunit mRNA and localization of α‐bungarotoxin binding proteins in the rat vestibular periphery
Authors: Wackym Phillip A. , Popper Paul , Lopez Ivan , Ishiyama Akira , Micevych Paul E.
Published: October 2002

In situ hybridization histochemistry was used to map the distribution of α2, α3, α4, and β2 nAChR subunit mRNAs throughout the peripheral vestibular system of the rat. The α4 and β2 nAChR subunit genes were co‐expressed by populations of primary afferent neurons within Scarpa's ganglion, while there was no expression of the α2, α3, α4, or β2 nAChR subunit genes by type I or type II vestibular hair cells. α‐bungarotoxin binding to nAChRs in the vestibular end‐organs was primarily limited to the afferent chalices surrounding type I hair cells and the basal aspect of type II hair cells. These data suggest that nAChRs composed of α4 and β2 subunits are localized on afferent chalices innervating the type I vestibular hair cells and that the direct cholinergic efferent innervation of the type II vestibular hair cells utilizes nAChR composed of other subunits.
Transforming growth factor alpha.
Authors: Kumar V. , Bustin S. A. , McKay I. A.
Published: October 2002

Transforming growth factor alpha (TGFα) is a close relative of epidermal growth factor (EGF), the first polypeptide mitogen discovered in 1962 (Cohen, 1962). TGFα, like EGF, exerts its effect on cells through binding to the EGF‐Receptor (EGF‐R). Here we review the molecular and cell biology of TGFα before proceeding to describe our own work on signaling molecules induced in response to activation of the EGF‐R.
Platelet‐derived growth factor.
Authors: Meyer‐Ingold W. , Eichner W.
Published: October 2002

Platelet‐derived growth factor (PDGF) is a potent activator for cells of mesenchymal origin. Two different PDGF chains termed A and B encoded by different genes have been identified leading to three different PDGF isoforms, the AA and BB homodimers and the AB heterodimer. All three forms have been observed in vivo and possess biological activity in vitro with the AA homodimer being the poorest cellular mitogen. The availability of highly purified recombinant PDGF isoforms was the initial basis for comparative studies in order to specify the different spectra of activity of the various PDGF species. This review is particularly focused on the AB heterodimer as from the standpoint of heterologous gene expression, this species is the one with the highest demands concerning expression and purification protocols. This explains the fact that, in comparison to PDGF‐BB, only very limited data on the in vivo application of PDGF‐AB are available so far.
Reconstituted human normal breast in nude mice using collagen gel or Matrigel.
Authors: Popnikolov Nikolay K. , Yang Jason , Guzman Raphael C. , Nandi Satyabrata
Published: October 2002

Human breast epithelial cells dissociated from reduction mammoplasty specimens were embedded in two commonly used extracellular matrices, type I collagen gel or Matrigel, and subsequently transplanted subcutaneously into athymic nude mice. Histological sections from both types of recovered gels showed epithelial structures arranged as short tubules with some branching as well as preservation of epithelial cell polarity. Proliferation was studied in vivo by 5‐bromo‐2′‐deoxy‐uridine labeling followed by immunostaining of sections from recovered gels. Human breast epithelia embedded in collagen gel or Matrigel had similar proliferative activity. Cholera toxin, 17β‐estradiol, and epidermal growth factor, when tested singly, were growth promoting, and in combination 17,β‐estradiol and cholera toxin had an additive effect but 17,β‐estradiol and epidermal growth factor were not additive. Our model system provides a means to study the endocrine control of normal human breast development.
Effects of bradykinin on Ca2+ mobilization and prostaglandin E2 release in human periodontal ligament cells.
Authors: Ogata Yorimasa , Niisato Naomi , Negishi Tetsuo , Sakurai Takeshi , Furuyama Shunsuke , Sugiya Hiroshi
Published: October 2002

In fura‐2‐loaded human periodontal ligament (HPDL) cells, bradykinin induced a rapidly transient increase and subsequently sustained increase in cytosolic Ca2+ ([Ca2+]i). When external Ca2+ was chelated by EGTA, the transient peak of [Ca2+]i was reduced and the sustained level was abolished, implying the Ca2+ mobilization consists of intracellular Ca2+ release and Ca2+ influx. Thapsigargin, a specific Ca2+‐ATPase inhibitor for inositol 1,4,5‐trisphosphate (1,4,5‐1P3)‐sensitive Ca2+ pool, induced an increase in [Ca2+]i in the absence of external Ca2+. After depletion of the intracellular Ca2+ pool by thapsigargin, the increase in [Ca2+]i induced by bradykinin was obviously reduced. Bradykinin also stimulated formation of inositol polyphosphates including 1,4,5‐IP3. These results suggest that bradykinin stimulates intracellular Ca2+ release from the 1,4,5‐1P3‐sensitive Ca2+ pool. Bradykinin stimulated prostaglandin E2 (PGE2) release in the presence of external Ca2+, but not in the absence of external Ca2+. Ca2+ ionophore A23187 and thapsigargin evoked the release of PGE2 in the presence of external Ca2+ despite no activation of bradykinin receptors. These results indicate that bradykinin induces Ca2+ mobilization via activation of phospholipase C and PGE2 release caused by the Ca2+ influx in HPDL cells.
Cell cycle‐dependent morphological changes in the actin cytoskeleton induced by agents which elevate cyclic AMP
Authors: McNamee Christine J. , Pennington Stephen R. , Sheterline Peter
Published: October 2002

Agents which increase the intracellular concentration of cyclic adenosine‐5′‐monophosphate, induce a highly arborised morphology in a proportion of sub‐confluent Swiss 3T3 fibroblasts. During this process the organisation of actin filaments progessively changes from a characteristic stress fibre pattern to leave a network of actin filaments within each and every arborisation. Despite this massive reorganisation of the actin cytoskeleton no changes are observed in the extent of polymerisation of actin during arborisation. The proportion of cells in asynchronous cultures undergoing arborisation at maximal concentrations of agents reaches a maximum of 30%; suggesting that the effect might be mediated only in cells during a restricted period of the cell cycle. More than 80% of serum‐starved cells responded to these agents between 1 and 8 hours after readdition of serum, but not at other times, suggesting that the arborisation response can occur only in the G1 phase of the cell cycle.
PARTIAL CHARACTERIZATION OF A PUTATIVE 110kDa MYOSIN FROM THE GREEN ALGACHARA CORALLINABYIN VITROBINDING OF FLUORESCENT F‐ACTIN
Authors: GROLIG FRANZ , SCHRÖDER JAN , SAWITZKY HEIKO , LANGE ULF
Published: October 2002

Using the binding of heterologous, rhodamine phalloidin‐labelled F‐actinin vitro, two F‐actin binding proteins were identified in protein extracts from the green algaChara corallinaafter fractionation by anion exchange chromatography. The first protein, a putative myosin, released laterally bound F‐actin at ATP‐concentrations as low as 1μm; equivalent concentrations of ADP were not effective. Binding of F‐actin was inhibited by the sulfhydryl‐alkylating agent N‐ethylmaleimide (NEM). Binding of F‐actin was also abolished by a monoclonal anti‐myosin (J14) previously used for immunodetection and immunolocalization in internodal cells (Groliget al., 1988,Eur J Cell Biol47: 22–31). Immunoblotting with J14 detected a 110kDa polypeptide only in those protein fractions that had revealed ATP‐sensitive binding of F‐actin. The putative myosin bound with mediocre affinity to immobilized calmodulin and free Ca2+‐concentration made no difference to this binding affinity. In contrast to the putative myosin, the second, less abundant protein revealed ATP‐insensitive and end‐wise binding to the microfilament and was not recognized by the anti‐myosin antibody.
TAXOL REDUCES THE RATE OF CYTOKINESIS IN PtK1CELLS
Authors: SNYDER JUDITH A. , MCLELLAND SANDRA L.
Published: October 2002

Mitotic PtK1cells were treated both during mid‐anaphase and at furrow initiation with the potent microtubule (MT) stabilizing agent, taxol, to determine the role of MTs in the rate of cytokinetic events. Rates of cytokinesis (μm/min) were measured by changes in furrow diameter. Incubation of PtK1cells during mid‐anaphase with 5 μg/ml taxol slows the rate of cytokinesis by an average of 43%. Instead of furrow initiation to midbody formation taking an average of 10.7 min (1.6 μm/min), furrowing to midbody formation was completed in an average of 19.0 min (0.9 μm/min), which does not include the 7‐min period between taxol application in mid‐anaphase and furrow initiation. Application of 5 μg/ml taxol to cells at furrow initiation had a reduced effect on decreasing the rate of cytokinesis and midbody formation; furrowing to midbody formation took an average of 14.6 min (1.2 μm/min). These data suggest that delays in the rate of cytokinesis is dependent on the mitotic stage at which taxol is applied. Ultrastructural analysis shows that taxol treatment of anaphase cells prevents midbody formation during early G1, yet MT number and organization in the furrowed region is not significantly altered from untreated cells. There is little change in the organization and amount of contractile ring microfilaments, yet filaments are also found parallel to midbody MTs. Our results may be explained by the fact that taxol tends to stabilize MTs which probably affects the rate at which they depolymerize in the terminal phases of cytokinesis. Reduction in depolymerization rates of a stable population of MTs could serve to regulate the rate of cytokinesis.
EXPRESSION OF PNA, WGA, SBA, AND Con A LECTIN RECEPTORS IN THE ADULT AND DEVELOPING HONEYBEE ANTENNAL LOBE
Authors: GASCUEL JEAN , GENECQUE EVELYNE , MASSON CLAUDINE
Published: October 2002

Glycoproteins are thought to play a crucial role in cell—cell interactions during nervous system ontogeny both in vertebrates and invertebrates. In order to investigate the putative involvement of such molecules during bee brain ontogeny we used lectins for their ability to bind specifically carbohydrate moieties. The expression of four lectin receptors, i.e. Arachis hypogea (PNA), Triticum vulgaris (WGA), Glycine max(SBA), and Concanavalin A (Con A) has been studied during pupal development and in the adult. The antennal lobe shows a complementary pattern of expression of Con A which stains both neuron somata and glomerular contours, and PNA, which stains the glomerular neuropile. SBA strongly stained the perineurium, trachea and mushroom body neuropile, while other neuropiles were not stained. WGA stained neuronal somata and the core of the glomeruli.
ALZHEIMER'S SOLUBLE AMYLOID BETA PROTEIN IS SECRETED BY HEPG2 CELLS AS AN APOLIPOPROTEIN
Authors: KOUDINOV ALEXEI R. , KOUDINOVA NATALIA V.
Published: October 2002

Recently we reported that the soluble form of amyloid beta protein (sAβ) in normal human plasma and cerebrospinal fluid is associated with lipoprotein (LP) particles. In this paper we tested the sAβ secretion by cells in association with LP in the model of the human hepatoma HepG2 cell line. These cells secreted sAβ to the culture media and expressed intracellular sAβ immunoreactivity. Soluble Aβ in the cell supernatant was detected in 200–300kDa LP complexes in association with apoA‐I, apoJ, transthyrethin and phospholipids, triglycerides and free and esterified cholesterol. This was assessed by size exclusion HPLC, immunoprecipitation with corresponding antibodies and by analysis of sAβ associated metabolically‐labeled lipids, respectively. Our results suggest that sAβ to LP association represents a unique mechanism, governing the normal biology of sAβ.
EFFECT OF THE IMPase INHIBITOR L690,330 ON SEA URCHIN DEVELOPMENT
Authors: SCONZO GABIELLA , CASCINO DOMENICO , AMORE GABRIELE , GERACI FABIANA , GIUDICE GIOVANNI
Published: October 2002

A variety of concentrations of the IMPase inhibitor L690,330 were added to sea urchin embryos. Immediate arrest of development was obtained for concentrations from 7.5mmon. Concentrations lower than 3.5mmpermitted gastrulation but inhibited skeletogenesis and disturbed elongation along the animal—vegetal axis. The latter results are similar to those obtained by counteracting lithium effect with myoinositol, which are suggested to be due to partial relief of IMPase inhibition.
CONTACT GUIDANCE OF CHICK EMBRYO NEURONS ON SINGLE SCRATCHES IN GLASS AND ON UNDERLYING ALIGNED HUMAN SKIN FIBROBLASTS
Authors: Stepień E. , Stanisz J. , Korohoda W.
Published: October 2002

The influence of substratum topography on the morphology and orientation of neurites of chick embryo neurons was studied.

Two series of experiments are reported. One concerned the behaviour of growth cones when the axons become contact‐guided by the surface texture. The second studied contact guidance of neurites extending on a compact layer of fixed aligned human skin fibroblasts (HSF).

It was observed that when the growth cones of sensory neurons isolated from dorsal root ganglions encountered a single scratch in a glass surface (0.1–2μm in depth and diameter) they turned and continued movement following the axis of the scratch. These neurons became contact‐guided as a result of the sequence of events. The growth cone filopodia recognized the irregularity in the substratum surface, whereas the growth cone lamella stabilized contact with the scratch and moved forward along the scratch axis. Scanning electron microscope revealed that the single scratches 150nm in width and ca. 100nm deep growth cone filopodia less than 200nm in diameter could detect and react by turning into them. These filopodia extensions followed the edge of scratches. However, phase contrast and Nomarski's differential interference contrast appeared insufficient for analysis of primary contact guidance of fine growth cone filopodia which themselves are often less than 200nm. In neuron cultures on fixed aligned HSF, the neuron aggregates assumed spindle‐like shapes, and sparsely seeded individual neurons extended axons along the long axes of the fibroblasts. The axons extended significantly further on the fixed underlying fibroblasts than on collagen‐covered glass. In crowded cultures of neurons, the cells extended neurites ignoring both the surface anisotropy (the scratches) and the orientation of the aligned fibroblasts. Immunofluorescence staining of neurons with antibodies against neurofilaments made it possible to analyse their shape and orientation on the fibroblasts. Computer‐assisted image analysis permitted the observed alignment of the neurites to be characteriezed quantitatively.
INDUCTION OF DIGOXIN‐LIKE MATERIAL PRODUCTION, AND THE DIGOXIN BINDING IN THE UNICELLULAR ORGANISM TETRAHYMENA BY DIGITOXIN
Authors: KOVÁCS P. , MÜLLER W. E. G. , CSABA G.
Published: October 2002

Thin layer chromatographic, and laser‐confocal microscopic analyses with a monoclonal antibody to digoxin also displaying high affinity to digoxigenin, were used to determine the presence and localization of cardioactive glycosides. Tetrahymena pyriformis was found to possess digitoxigenin‐like material, but digoxin, digitoxin, digoxigenin, gitoxin and lanatoside C were not detected. Digitoxin treatment elicited the appearance of a digoxin‐like material in the progeny generations. Digoxin was taken up by untreated Tetrahymena, especially strongly 24h after digitoxin treatment. While the cardenolide was localized in vesicles of the cell body in untreated Tetrahymena, the engulfed digoxin appeared in the epiplasmic layer and also in the cilia after digitoxin pretreatment. Digoxin pretreatment did not increase digoxin uptake. These data indicate that Tetrahymena has: (1) the capacity to discriminate between closely related molecules; (2) the ability to induce digoxin‐like material production; and/or (3) enzymes that can effect a digitoxin—digoxin transformation.
A Na+‐DEPENDENT SYSTEM A AND ASC‐INDEPENDENT AMINO ACID TRANSPORT SYSTEM STIMULATED BY GLUCAGON IN RAT HEPATOCYTES
Authors: Lim Soo Kyung , Cynober Luc , DE Bandt Jean‐Pascal , Aussel Christian
Published: October 2002

The effects of glucagon on amino acid transport in rat hepatocytes are not fully understood. We examined the effect of this hormone on alanine, serine and cysteine preferring system (system ASC)‐mediated amino acid transport in rat hepatocyte monolayers using 2‐aminoisobutyric acid (AIB) and L ‐cysteine. Glucagon induced a time and protein synthesis‐dependent stimulation of Na+‐dependent alanine preferring system (system A)‐independent AIB transport. The glucagon‐induced increase in transport activity was not modified by substrate starvation and not related to changes in the intracellular pool of amino acids. Glucagon did not modify system ASC activity measured by L ‐cysteine. Therefore the transport activity of AIB independent of system A stimulated by glucagon cannot be attributed to system ASC. This suggests a Na+‐dependent transport system in rat hepatocytes not identified until now.
CLONING AND CHARACTERIZATION OF THE GENE ENCODING THE HIGHLY EXPRESSED RIBOSOMAL PROTEIN L3 OF THE CILIATED PROTOZOANTETRAHYMENA THERMOPHILA. EVIDENCE FOR DIFFERENTIAL CODON USAGE IN HIGHLY EXPRESSED GENES
Authors: Larsen Leif K. , Andreasen Per H. , Dreisig Hanne , Palm Lisbeth , Nielsen Henrik , Engberg Jan , Kristiansen Karsten
Published: October 2002

We have cloned and characterized the cDNA and the macronuclear genomic copy of the highly conserved ribosomal protein (r‐protein) L3 of Tetrahymena thermophila. The r‐protein L3 is encoded by a single copy gene interrupted by one intron. The organization of the promoter region exhibits features characteristic of ribosomal protein genes inTetrahymena. The codon usage of the L3 gene is highly biased. A thorough analysis of codon usage in Tetrahymena genes revealed that genes could be categorized into two classes according to codon usage bias. Class A comprises r‐protein genes and a number of other highly expressed genes. Class B comprises weakly expressed genes such as the conjugation induced CnjB and CnjC genes, but surprisingly, this class also contains abundantly expressed genes such as the genes encoding the surface antigens SerH3 and SerH1. Codon usage is slightly more restricted in class A than in class B, but both classes exhibit distinct and different codon usage biases. Class A genes preferentially use C and U in the silent third codon positions, whereas class B genes preferentially use A and U in the silent third codon positions. The analysis suggests that two different strategies have been employed for optimization of codon usage in the A+T‐rich genome of Tetrahymena.
INVOLVEMENT OF GLUTATHIONE AND GLUTATHIONE‐RELATED ENZYMES IN THE PROTECTION OF NORMAL AND TRISOMIC HUMAN FIBROBLASTS AGAINST DAUNORUBICIN
Authors: Zatorska Agnieszka , Józwiak Zofia
Published: October 2002

We measured the glutathione content, and the activity of glutathione‐related enzymes and DT‐diaphorase in cultured normal (cell line: S‐126) and trisomic (cell lines: S‐158, S‐240) human fibroblasts exposed to daunorubicin (DNR). Determination of reduced and total glutathione levels, and measurement of the activity of glutathione peroxidase, glutathione reductase, glutathione‐S‐transferase and DT‐diaphorase were performed spectrophotometrically. Human fibroblasts were exposed to 4μ m DNR for 2h, and the cells placed in drug‐free medium for 6, 12, 24, 48, and 72h. Cellular levels of GSH and total glutathione decreased following exposure to DNR. However, the ratio of GSH to total glutathione returned to control levels only in trisomic cells. These changes were concomitant with increasing glutathione‐S‐transferase and glutathione reductase activities. DNR also significantly increased the activity of Se‐independent peroxidase and DT‐diaphorase in trisomic fibroblasts. Marked increases in the activity of Se‐dependent peroxidase and DT‐diaphorase alone were seen in normal cells. The results provide the first evidence that DNR can induce alterations in the level of glutathione and glutathione‐dependent enzymes in trisomic fibroblasts as compared to normal cells, which may provide additional protection against daunorubicin‐induced oxidative stress in trisomic fibroblasts.
EXTREMELY LOW FREQUENCY (ELF) PULSED‐GRADIENT MAGNETIC FIELDS INHIBIT MALIGNANT TUMOUR GROWTH AT DIFFERENT BIOLOGICAL LEVELS
Authors: Zhang Xinchen , Zhang Husheng , Zheng Congyi , Li Chaoyang , Zhang Xinsong , Xiong Wei
Published: October 2002

Extremely low frequency (ELF) pulsed‐gradient magnetic field (with the maximum intensity of 0.6–2.0T, gradient of 10–100T·M−1, pulse width of 20–200ms and frequency of 0.16–1.34Hz treatment of mice can inhibit murine malignant tumour growth, as seen from analyses at different hierarchical levels, from organism, organ, to tissue, and down to cell and macromolecules. Such magnetic fields induce apoptosis of cancer cells, and arrest neoangiogenesis, preventing a supply developing to the tumour. The growth of sarcomas might be amenable to such new method of treatment.
Late Quaternary Environmental and Climatic Changes in Central Brazil
Authors: Ledru Marie-Pierre
Published: October 2002

Paleoenvironmental changes dating back to 30,000 yr B.P. documented in a pollen record from central Brazil (lat. 19°S) permit the reconstruction of climatic changes related to shifts of the Antarctic polar fronts. The paleoclimatic inferences were obtained by a study of modern vegetation and pollen distribution, taking into account present-day climatic parameters. At 30,000 yr B.P. the climate must have been warmer and moister than today judging from the high amount of tree pollen taxa characteristic of floodplain forest. From 17,000 to 14,000 yr B.P. the climate was drier although tree pollen percentages were relatively high. After 12,000 yr B.P.Araucariaforest elements increased, suggesting a moister and cooler climate. TheAraucariaforest disappeared during a short interval between 11,000 and 10,000 yr B.P. This could be related to the Younger Dryas event. At the beginning of the Holocene the climate became cool and moist again, as indicated by the reexpansion of theAraucariaforest. The latter was progressively replaced by a mesophytic semideciduous forest indicating warmer and drier climate after 8500 yr B.P. At 5000 yr B.P. an arid interval was followed by the expansion of mesophytic semideciduous forest elements.
A Model of Pollen Source Area for an Entire Lake Surface
Authors: Sugita Shinya
Published: October 2002

A model of pollen deposition on the surface of an entire basin is developed to estimate pollen source area, and results are compared with those for a point at the center of a basin (I. C. Prentice, 1985,Quaternary Research23, 76-86; 1988, "Vegetation History," (pp. 17-42, Kluwer Academic). This model is more appropriate for approximating the source area of pollen in lake sediment, since mixing in lake water and focusing of sediment redistribute pollen originally deposited over the entire surface. In general, the pollen source radius for the entire basin surface is 10-30% smaller than the source radius for a point at the center; the difference in the source radius is more profound for heavier pollen types such as spruce and sugar maple than for lighter types such as oak and ragweed. The average pollen input to the entire surface is more strongly influenced by nearby pollen sources than pollen deposition at the center. The pollen record from a lake may therefore provide different spatial resolution than the record from a bog of similar radius.
Late Quaternary Records of the Atmospheric Input of Eolian Dust to the Center of the Chinese Loess Plateau
Authors: Zhang Xiaoye , An Zhisheng , Chen Tuo , Zhang Guangyu , Arimoto Richard , Ray Barbara J.
Published: October 2002

The concentrations of 15 elements and mineral grain-size distributions were determined for Late Quaternary loess sediments from the Chinese Loess Plateau. Particle-size distributions of the loess were approximately log-normal for each of three modes (i.e., 0.04 to 1 μm diameter, 2 to 20 μm, and 20 to 200 μm) that integrate the transport and deposition of eolian dust. The mass particle-size distributions of typical crustal elements (Si, Ca, Fe, Ti, K, Mn, and V) in paleosol and loess samples show patterns similar to those of mineral aerosols, but higher concentrations occur in the submicrometer sediment particles. Absolute principal component analysis of the elemental data suggests that the loess can be described in terms of synsedimentary and postdepositional concentration and subvertical migration of CaCO3 and various elements through the deposit. A variety of geochemical indicators in the loess are apparently sensitive to Asian monsoon variations; these include the mass ratio of course to fine particles, the concentration ratios of certain trace elements, the elemental fluxes associated with eolian dust, and the bulk concentration of Ca in the sediments.