bluuebunny/crossref_metadata_2025_split huggingface dataset:
Competitive Hebbian learning and the hippocampal place cell system: Modeling the interaction of visual and path integration cues
Authors: Guazzelli Alex , Bota Mihail , Arbib Michael A. 
Published: August 2002

AbstractThe hippocampus has long been thought essential for implementing a cognitive map of the environment. However, almost 30 years since place cells were found in rodent hippocampal field CA1, it is still unclear how such an allocentric representation arises from an egocentrically perceived world. By means of a competitive Hebbian learning rule responsible for coding visual and path integration cues, our model is able to explain the diversity of place cell responses observed in a large set of electrophysiological experiments with a single fixed set of parameters. Experiments included changes observed in place fields due to exploration of a new environment, darkness, retrosplenial cortex inactivation, and removal, rotation, and permutation of landmarks. To code for visual cues for each landmark, we defined two perceptual schemas representing landmark bearing and distance information over a linear array of cells. The information conveyed by the perceptual schemas is further processed through a network of adaptive layers which ultimately modulate the resulting activity of our simulated place cells. In path integration terms, our system is able to dynamically remap a bump of activity coding for the displacement of the animal in relation to an environmental anchor. We hypothesize that path integration information is computed in the rodent posterior parietal cortex and conveyed to the hippocampus where, together with visual information, it modulates place cell activity. The resulting network yields a more direct treatment of partial remapping of place fields than other models. In so doing, it makes new predictions regarding the nature of the interaction between visual and path integration cues during new learning and when the system is challenged with environmental changes. Hippocampus 2001;11:216–239. © 2001 Wiley‐Liss, Inc.
A policy of introducing a new contract and funding system of general practice in Estonia
Authors: Lember Margus 
Published: August 2002

AbstractThe socialist bloc of post‐war Europe was obliged to follow the Soviet example with a hierarchical, centrally controlled health care system based on polyclinics and other facilities providing extensive specialist services at the first level of contact. All the countries of Central and Eastern Europe have now expressed their wish to totally change their health care systems. Changes in these countries include: the introduction of market economy mechanisms in health care, an increased focus on population health needs in guiding health care systems, and the possibility of introducing a more general type of care at primary level. Patient expectations of access, choice and convenience are factors in shaping new models of health care delivery. Appropriate timing is the key determinant of the success of reforms. In Estonia the beginning of the 1990s was the time when several interest groups in society supported changes in the health care system. The first step after regaining independence was the reintroduction of a Bismarck‐type insurance system. In the late 1990s the primary care reforms have changed the initial plans and elements of a National Health Service were introduced, especially general practitioners' lists, capitation payment and gate‐keeping principles. The family medicine reform in Estonia has two main objectives: introduction of general practice as a specialty into Estonian health care and changing the remuneration system of primary care doctors. The specific tasks are: to provide practising primary care doctors with opportunities for retraining to gain the specialty status of a general practitioner, to create a list system for the population to register with a primary care doctor, to introduce a partial gate‐keeping system and to give the status of the independent contractor to primary care doctors. Copyright © 2002 John Wiley & Sons, Ltd.
The acute effects of an extract of Bacopa monniera (Brahmi) on cognitive function in healthy normal subjects
Authors: Nathan P. J. , Clarke J. , Lloyd J. , Hutchison C. W. , Downey L. , Stough C. 
Published: August 2002

AbstractThe Ayurvedic medicine Bacopa monniera (Brahmi) has been shown to exert cognitive enhancing effects in animals. The current study examined the acute effects of an extract of Bacopa monniera on cognitive function in normal healthy human subjects. The study was a double‐blind, placebo‐controlled independent group design in which subjects were randomly allocated to one of two treatment conditions, Bacopa monniera (300 mg) (n = 18) or placebo (n = 20). Neuropsychological testing was conducted before and 2 h after drug administration. No significant changes were found on any of the tests. The findings suggest that Bacopa monniera, at least for the dose administered, has no acute effects on cognitive functioning in normal healthy subjects. Copyright © 2001 John Wiley & Sons, Ltd.
Hysteresis‐based flood‐wave analysis using the concept of strain
Authors: Mishra Surendra Kumar , Singh Vijay P. 
Published: August 2002

AbstractHysteresis represents a loop in a rating curve and is a phenomenon which closely resembles that occurring in stress–strain curves used for studying the elastic properties of solid substances in engineering mechanics. Earlier hysteresis‐based studies used for defining floodwave propagation in open channels have qualitatively shown that hysteresis is an index of energy loss during floodwave propagation. Using the concept of elasticity, this paper introduces a new term called flow strain (defined as the ratio of change in discharge to the initial discharge) for investigating hysteresis. The usefulness of this new term is evaluated with use of four dam‐break studies. The study reveals that:

flow strain is a function of three wave speeds, Seddon speed, Lagrange speed, and elastic speed;
a single linear reservoir concept frequently used in flood routing is a specific variant of the Seddon speed formula;
the non‐linear storage–discharge relationship, widely used in overland flow modelling, is a variant of the kinematic wave representation;
the discharge ordinates on the recession part of a hydrograph follow a simple first‐order autoregressive form;
the hysteresis, phase difference and logarithmic decrement all define attenuation and are indices of energy loss during floodwave propagation.
Copyright © 2001 John Wiley & Sons, Ltd.
Effects of the spatial organization of agricultural management on the hydrological behaviour of a farmed catchment during flood events
Authors: Moussa Roger , Voltz Marc , Andrieux Patrick 
Published: August 2002

AbstractField limits, tillage practices and ditch networks constitute man‐made hydrological discontinuities in farmed catchments, and are expected to influence hydrological response during flood events. The purpose of this study is to assess the role of human impact, especially the existence of tillage practices and ditch network, on flood events. The study area is the farmed catchment of Roujan (0·91 km2) located in Southern France for which a spatially distributed hydrological model, MHYDAS, was developed and tested. The model considers the catchment as a series of interconnected field parts linked to the ditch network. Descriptions are provided for the main model procedures: computation of Hortonian excess rainfall on fields using the Green and Ampt approach, conversion of excess rainfall to surface runoff, interaction between ditch network and groundwater using a simple Darcian model and flood routing through the ditch network using the diffusive wave model. To analyse the role of both tillage practices and the ditch network, two sets of sensitivity analysis of the model were applied. The first set studied the role of tillage practices by comparing the actual spatial distribution of tillage practices on the catchment with three hypothetical scenarios. The second set studied the role of the ditch network by comparing the actual man‐made ditch network with a hypothetical drainage network automatically extracted from a digital elevation model. Results show the importance of the role of tillage and the ditch network on the form of the hydrograph, the lag time, the runoff volume and the peak discharge. This technique could also be applied to study the impact of land use change on the hydrological behaviour of the catchment. Copyright © 2002 John Wiley & Sons, Ltd.
P53: An ubiquitous target of anticancer drugs
Authors: Blagosklonny Mikhail V. 
Published: August 2002

AbstractThe p53 tumor suppressor can induce growth arrest, apoptosis and cell senescence. Not surprisingly, p53 is an appealing target for therapeutic intervention. Although current anticancer agents do not directly interact with p53, these agents (including DNA damaging drugs, antimetabolites, microtubule‐active drugs and inhibitors of the proteasome) cause accumulation of wt p53. Depending on the p53 status of cancer cells, diverse therapeutic strategies are under development. These include pharmacological rescue of mutant p53 function and reactivation of wt p53 in E6‐expressing cells. For protection of normal cells, strategies range from abrogation of wt p53 induction, thereby decreasing the toxicity of DNA damaging agents, to activation of wt p53‐dependent checkpoints, thereby protecting cells against cell cycle‐dependent therapeutics. © 2001 Wiley‐Liss, Inc.
Antitumor activity of the selective epidermal growth factor receptor‐tyrosine kinase inhibitor (EGFR‐TKI) Iressa® (ZD1839) in an EGFR‐expressing multidrug‐resistant cell line in vitro and in vivo
Authors: Naruse Ichiro , Ohmori Tohru , Ao Yoko , Fukumoto Hisao , Kuroki Toshio , Mori Masatomo , Saijo Nagahiro , Nishio Kazuto 
Published: August 2002

AbstractSelective tyrosine kinase inhibitors are regarded as promising antitumor agents for cancer treatment. Iressa® (ZD1839) is an orally active, selective EGFR‐TKI (epidermal growth factor receptor‐tyrosine kinase inhibitor) that blocks signal transduction pathways implicated in cancer cell proliferation, survival and other host‐dependent processes promoting cancer growth. The cellular mechanisms of ZD1839 action against human malignant cells and drug‐resistant cells were evaluated in vitro. Among the cell lines tested, ZD1839 showed a strong growth‐inhibitory effect in vitro on human leukemic cells resistant to phorbol ester. This cell line, K562/TPA, shows a non‐P‐glycoprotein‐mediated multidrug‐resistant phenotype. The IC50 value of ZD1839 on K562/TPA was approximately 400‐fold lower than that on the parental K562 cell (K562 = 12 ± 2 μM; K562/TPA = 0.025 ± 0.002 μM) in vitro as determined by a dye formation assay. The expression of EGFR and EGFR mRNA was clearly present in K562/TPA but not in parental K562 cells as determined by Western blotting and RT‐PCR. EGFR was autophosphorylated in K562/TPA detected by the antiphosphotyrosine antibody. The in vivo antitumor effects of ZD1839 on K562 and K562/TPA cells were also investigated in BALB/c nude mice. K562/TPA cells transplanted subcutaneously into mice disappeared completely with ZD1839 treatment (20 mg/kg/day, days 3–9). This was not the case in K562 cells. These results suggest that ZD1839 is highly active against tumor cells with non‐P‐glycoprotein‐mediated multidrug resistance that express EGFR. Iressa® is a trademark of AstraZeneca (Cheshire, UK). © 2001 Wiley‐Liss, Inc.
Prostate cancer mortality reduction by screening: Power and time frame with complete enrollment in the European randomised screening for prostate cancer (ERSPC) trial
Authors: de Koning Harry J. , Liem Michael K. , Baan Caroline A. , Boer Rob , Schröder Fritz H. , Alexander on behalf of ERSPC Freda E. 
Published: August 2002

AbstractFrom 1992–2001, 7 countries in Europe gradually recruited men for the European Randomised Screening for Prostate Cancer (ERSPC) trial. Centres recruit different age groups and have different designs for recruiting and countries have different underlying risks for prostate cancer. Recruitment has reached 163,126 men aged 55–69 at entry now. Our purpose was to calculate the power of the trial and at what point in time can statistically significant differences in prostate cancer mortality be expected. Recruitment data were collected from the screening centres. We calculated the expected number of prostate cancer deaths in each follow‐up year, based on national statistics and expected rate in trial entrants. The power was calculated using different assumptions on intervention effect and contamination rate and also if the ERSPC trial would cooperate with other trials. With an assumed 25% intervention effect in men actually screened and a 20% contamination rate, the trial will reach a power of 0.86 in 2008. With an assumed intervention effect of 40%, the power reaches 0.90 in 2003–2004. Pooling data with those of the Prostate, Lung, Colorectal and Ovary (PLCO) trial early is expected to improve the power to 79% (20% intervention effect) to 92% (40% intervention effect PLCO). Adding more centres with compliance rates lower than 45% decreases the power of the trial. The ERSPC trial has sufficient power to detect a significant difference in prostate cancer mortality between the 2 arms if the true reduction in mortality by screening is 25% or more or if contamination remains limited to 10% if the true effect is 20% or more. If early detection and treatment turns out to have a stronger effect as may be suggested by observational data, the ERSPC trial is likely to conclusively show that within the next 5 years. © 2001 Wiley‐Liss, Inc.
Novel epidemiologic evidence for the association between fermented fish sauce and esophageal cancer in South China
Authors: Ke Li , Yu Ping , Zhang Z. Xin 
Published: August 2002

AbstractPrevious studies have suggested that fermented fish sauce is related to an increased risk for nasopharyngeal, thyroid and gastric cancers and has suspicious carcinogenic and promoting effects in the laboratory, but these reports have not investigated the association between this agent and esophageal cancer in population. Therefore, we investigated the relationship between esophageal cancer and consumption of fermented fish sauce, alcohol and tobacco after adjusting other risk factors using data from a large hospital‐based case‐control study in Chaoshan area of China. The subjects for analysis included 1,248 cases (median age 58.5 [range 29–82] years, 936 males, 312 females, some 50% with the habit of fermented fish sauce eating) with squamous cell carcinoma of the esophagus and the same amount of controls matched by sex and age. A significant increase in risk (OR 3.21; 95% CI 2.45–4.19) for eating fermented fish sauce compared to not eating and a significant dose‐response relationship was found with the consumption of fermented fish sauce (p for trend < 0.001). In comparison based on the binary variables, the OR for the subjects with fermented fish sauce eating and current smoking was 15.5 with a 95% CI of 8.14–29.3, relative to those exposed to neither habit. The joint effect of fermented fish sauce (F) and smoking (S) was more than additive (F * S > F + S: 15.5 > 1 + (5.6 − 1) + (6.6 − 1)), but the effect for fermented fish sauce and alcohol was not found. It is concluded that risks of esophageal cancer in the population were substantially associated with fermented fish sauce. Further epidemiologic and experimental study are required to find a biologic causal relationship between them. © 2002 Wiley‐Liss, Inc.
Effects of cytarabine and various anthracyclins on platelet activation: Characterization of in vitro effects and their possible clinical relevance in acute myelogenous leukemia
Authors: Foss Brynjar , Ulvestad Elling , Hervig Tor , Bruserud Øystein 
Published: August 2002

AbstractPrevious in vitro studies have demonstrated that normal platelets and platelet‐released mediators can alter in vitro characteristics of human acute myelogenous leukemia (AML) blasts. To further investigate whether platelets can be expected to adhere to and thereby affect AML blasts through their release of soluble mediators into a common microenvironment, we investigated (i) the effects on platelet activation by cytotoxic drugs commonly used in AML therapy; (ii) the occurrence of circulating activated platelets in acute leukemia patients; and (iii) the in vivo and in vitro adherence of platelets to AML blasts. The anthracyclins daunorubicin and idarubicin increased the expression of activation‐associated membrane molecules (GPIIb/IIIa, CD62P, CD63) by normal platelets, daunorubicin then having the strongest effect. In contrast, cytarabine, epirubicin, doxorubicin and mitoxantrone had no significant effects. Although AML patients did not show increased levels of activated platelets in the circulation, adhesion of platelets to AML blasts was demonstrated both in vivo and in vitro. These results suggest that platelets and AML blasts may locate to common in vivo microenvironments, and platelet‐derived soluble mediators may thereby affect the functional characteristics of the leukemia cells. © 2002 Wiley‐Liss, Inc.
Increased expression of T‐fimbrin gene after DNA damage in CHO cells and inactivation of T‐fimbrin by CpG methylation in human colorectal cancer cells
Authors: Sasaki Yasushi , Itoh Fumio , Kobayashi Toshihisa , Kikuchi Takefumi , Suzuki Hiromu , Toyota Minoru , Imai Kohzoh 
Published: August 2002

AbstractWhen DNA damage is induced by unprogrammed extrinsic events, activating‐cell‐cycle checkpoints delay cell‐cycle progression in the G1 or G2 phases and allow repair of a damaged template. In this study, we evaluated changes in gene expression upon radiation‐induced G2 cell‐cycle arrest using Chinese hamster ovary (CHO) cells. T‐fimbrin, an actin‐binding protein, was overexpressed in CHO cells in which G2 arrest had been induced by X‐radiation. Northern blot analysis revealed that T‐fimbrin gene expression was induced not only by X‐radiation but also by a topoisomerase II inhibitor, etoposide. Transfection of CHO cells with a vector encoding T‐fimbrin antisense RNA demonstrated that reduced T‐fimbrin expression induced alterations in cell‐cycle control; radiation‐induced G2 arrest was short and decreased in cells transfected with antisense T‐fimbrin. Additionally, T‐fimbrin gene expression was suppressed in a human colorectal cancer cell line, SW948, because of promoter‐specific DNA methylation. These results suggest that downregulation of T‐fimbrin may be involved in cancer development through G2/M cell‐cycle control in mammalian cells. © 2002 Wiley‐Liss, Inc.
Living arrangements and support relationships among elderly Indonesians: case studies from Java and Sumatra
Authors: Beard Victoria A. , Kunharibowo Yacobus 
Published: August 2002

AbstractThroughout Asia the proportions of national populations aged 65 years and above are predicted to grow rapidly over the next 50 years. While this process of ageing is already well underway in the more economically developed countries in East Asia, it is just beginning to accelerate in Southeast Asia. This increase in the proportion of the elderly population creates new demands for social and economic support, and simultaneously brings to the forefront the concern that changing household structures will translate into a decline in support for the elderly. Presently, in Indonesia most elderly parents co‐reside with their adult children. However, preliminary studies provide some evidence that casts doubt on the presumed relationship between co‐residence and receipt of support. This paper uses qualitative case studies of elderly parents and their adult children to examine the connection between living arrangements and support relationships. We collected data for the case studies through the use of in‐depth interviews, direct observation, and a structured household questionnaire. We conducted the case studies in urban and rural areas on Java and Sumatra, respectively, and we focused upon two distinct sociocultural groups: the Javanese and the Batak Karo. The use of different geographical locations allowed us to evaluate how the urban and rural environment, as well as traditional sociocultural norms, shaped the preferences and behaviours of elderly parents and their adult children. This paper argues for the conceptual separation of living arrangements and support relationships, and it suggests the existence of a support continuum that has six distinct levels, ranging from level 1 (elderly parents completely supporting adult child) to level 5 (adult child completely supporting elderly parents), with level 6 indicating no exchange of support whatsoever. Primarily, ‘support’ refers to transfers of time and money; however, the case‐study approach facilitates the evaluation of less quantifiable aspects of support, including companionship, knowledge and experience. Based on evidence from the case studies, it appears that some elderly parents completely support their adult children; however, in most cases the relationship between parent and child is reciprocal. Because these relationships are often subtle, they are easily missed when researchers rely on highly structured methods of data collection. This study of the support continuum in Indonesia will be of use to anyone seeking to understand the complex and nuanced relationships that exist between the elderly and their children. The case studies, besides providing a window through which to observe the Indonesian household, also provide insights that will be useful to those who wish to design structured survey instruments. Copyright © 2001 John Wiley & Sons, Ltd.
Estimation of unsaturated flow in layered soils with the finite control volume method
Authors: Arampatzis George , Tzimopoulos Christos , Sakellariou‐Makrantonaki Maria , Yannopoulos Stavros 
Published: August 2002

AbstractWater movement in unsaturated soil is described by Richards' equation, which is strongly nonlinear and cannot be solved analytically. For this reason numerical methods such as finite difference and finite element methods have been used to solve it. This paper presents another numerical solution of Richards' equation, based on the finite control volume method. This method has important advantages over other numerical methods, such as conservativeness of the system and flexibility of the grid intervals. To validate the numerical model a series of experiments were carried out in the laboratory in a vertical column of unsaturated two‐layered soil (coarse and fine sand). The upper boundary condition was a second kind or Newman one and the lower boundary condition was a third kind or Newton's law condition. The soil water content was measured using the γ‐ray absorption method, while the water pressure in the pore media was measured using a tensiometer system with ceramic cups and pressure transducers. The numerical results of the new computational scheme are in good agreement with the experimental points. Copyright © 2001 John Wiley & Sons, Ltd.