bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancement of dendritic branching in cultured hippocampal neurons by 17β‐estradiol is mediated by nitric oxide
Authors: Audesirk T. , Cabell L. , Kern M. , Audesirk G. 
Published: April 2003

AbstractBoth 17β‐estradiol (E2) and nitric oxide (NO) are important in neuronal development, learning and memory, and age‐related memory changes. There is growing evidence that a number of estrogen receptor‐mediated effects of estradiol utilize nitric oxide as an intermediary. The role of estradiol in hippocampal neuronal differentiation and function has particular implications for learning and memory.Low levels of estradiol (10 nM) significantly increase dendritic branching in cultured embryonic rat hippocampal neurons (158% of control). This study investigates the hypothesis that the estrogen‐stimulated increase in dendritic branching is mediated by nitric oxide. We found that nitric oxide donors also produce significantly increased dendritic branching S‐nitroso‐N‐acetylpenicillamine (SNAP: 119%; 2,2′‐(hydroxynitrosohydrazino)bis‐ethanamine (NOC‐18): 128% of control). We then determined that the increases in dendritic branching stimulated by estradiol or by a nitric oxide donor were both blocked by an inhibitor of guanylyl cyclase. Dendritic branching was also stimulated by a cell permeable analog of cyclic guanosine monophosphate (dibutyryl‐cGMP: 173% of control). Estradiol‐stimulated dendritic branching was reversed by the nitric oxide scavenger 2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethyl imidazoline‐1‐oxyl 3‐oxide (carboxy‐PTIO). This study provides evidence that estradiol influences the development of embryonic hippocampal neurons in culture by increasing the production of nitric oxide or by increasing the sensitivity of the neurons to nitric oxide. Nitric oxide in turn stimulates dendritic branching via activation of guanylyl cyclase.
An accounting analysis of the risk‐return relationship in bull and bear markets
Authors: Kim Moon K. , Ismail Badr E. 
Published: April 2003

AbstractThis study provides evidence that accounting beta (earnings and cash flow‐based) provides information consistent with the risk‐return relationship in up‐ and down‐markets. We are not able, however, to provide similar evidence using market beta. Considering that investors' ability to assess the risk‐return trade‐off in up‐ and down‐markets is central to efficient portfolio formation, the results suggest that accounting data can provide appropriate measures of portfolio upside and downside risk.
Nonlinear accumulation in the brain of the new taxoid TXD258 following saturation of P‐glycoprotein at the blood–brain barrier in mice and rats
Authors: Cisternino Salvatore , Bourasset Fanchon , Archimbaud Yves , Sémiond Dorothée , Sanderink Gérard , Scherrmann Jean‐Michel 
Published: April 2003

TXD258, a new taxoid antitumor agent, is a poor substrate for the P‐glycoprotein (P‐gp) in Caco‐2 cells. In this study, we investigated the amount of drug accumulating in the brains of rats and mice under a variety of conditions (dose and infusion time, species and plasma concentration) using conventional in vivo pharmacokinetic techniques and in situ brain perfusion.
Mice were infused with radiolabeled TXD258 at 15, 30, 45 and 90 mg m−2 for 45 s or 1 h and rats were infused with 15 and 60 mg m−2 over 2.3 min. The radioactivity in the plasma and brains was measured. The brain concentrations of TXD258 in mice and rats were maximal from 2 min to 1 h postinfusion and radioactivity was still detectable at 168 h. While the plasma concentration of TXD258 increased linearly in mice with the infused dose, the brain content increased more than proportionally with the dose between 15 and 90 mg m−2. This nonlinear uptake of TXD258 also occurred in the plasma and brain of the rat.
These findings suggest that the protein‐mediated efflux across the blood–brain barrier (BBB) becomes saturated. In situ brain perfusion studies confirmed that TXD258 is a P‐gp substrate at the BBB of mice and rats. The P‐gp of both species was saturated at the half‐inhibitory concentration (∼13 μM) produced by i.v. infusion.
Thus, the observed nonlinear accumulation of TXD258 in the brain seems to occur by saturation of the P‐gp at the rodent BBB. This saturation could have several advantages, such as overcoming a P‐gp‐mediated efflux, but the nonlinear pharmacokinetics could increase the risk of toxicity.

British Journal of Pharmacology (2003) 138, 1367–1375. doi:10.1038/sj.bjp.0705150
Effects of bisphenol A on antigen‐specific antibody production, proliferative responses of lymphoid cells, and TH1 and TH2 immune responses in mice
Authors: Yoshino Shin , Yamaki Kouya , Yanagisawa Rie , Takano Hirohisa , Hayashi Hideyuki , Mori Yoki 
Published: April 2003

We investigated the effect of bisphenol A (BPA), which binds estrogen receptors, on immune responses including production of antigen‐specific antibodies, proliferative responses of lymphoid cells, and Th1 and Th2 responses.
For this investigation, mice were p.o. given varying doses including 3, 30, 300, and 3000 μg kg−1 of BPA immediately after immunization with hen egg lysozyme (HEL) (day 0) and then daily by day 20. On day 21, anti‐HEL IgG antibodies in sera and proliferative responses of spleen cells to the antigen were measured. Anti‐HEL IgG2a antibodies and IFN‐γ secreted from splenic lymphocytes were also measured as indicators of Th1 immune responses, while anti‐HEL IgG1 antibodies and IL‐4, as those of Th2 responses.
The results showed that treatment with 3000 μg kg−1 of BPA was followed by a significant increase in anti‐HEL IgG as well as the antigen‐specific cell proliferation. Anti‐HEL IgG2a production and IFN‐γ secretion were significantly enhanced in mice treated with 300 and 30 μg kg−1 of BPA, respectively, while anti‐HEL IgG1 production and IL‐4 secretion were augmented in animals given 3000 and 300 μg kg−1 of the chemical, respectively.
Augmentation of these immune responses was also observed in mice exposed to 0.3–30 μg kg−1 of estradiol, although Th1 responses appeared to be more sensitive to the sex hormone than Th2 responses.
These results suggest that BPA may play a role in augmenting immune responses, especially Th1 responses.

British Journal of Pharmacology (2003) 138, 1271–1276. doi:10.1038/sj.bjp.0705166
Neuroprotection by caffeine and adenosine A2A receptor blockade of β‐amyloid neurotoxicity
Authors: Dall'lgna Oscar P , Porciúncula Lisiane O , Souza Diogo O , Cunha Rodrigo A , Lara Diogo R 
Published: April 2003

Adenosine is a neuromodulator in the nervous system and it has recently been observed that pharmacological blockade or gene disruption of adenosine A2A receptors confers neuroprotection under different neurotoxic situations in the brain. We now observed that coapplication of either caffeine (1–25 μM) or the selective A2A receptor antagonist, 4‐(2‐[7‐amino‐2(2‐furyl)(1,2,4)triazolo (2,3‐a)(1,3,5)triazin‐5‐ylamino]ethyl)phenol (ZM 241385, 50 nM), but not the A receptor antagonist, 8‐cyclopentyltheophylline (200 nM), prevented the neuronal cell death caused by exposure of rat cultured cerebellar granule neurons to fragment 25–35 of β‐amyloid protein (25 μM for 48 h), that by itself caused a near three‐fold increase of propidium iodide‐labeled cells. This constitutes the first in vitro evidence to suggest that adenosine A2A receptors may be the molecular target responsible for the observed beneficial effects of caffeine consumption in the development of Alzheimer's disease.British Journal of Pharmacology (2003) 138, 1207–1209. doi:10.1038/sj.bjp.0705185
Cardiac‐specific overexpression of human β2 adrenoceptors in mice exposes coupling to both Gs and Gi proteins
Authors: Hasseldine A R G , Harper E A , Black J W 
Published: April 2003

Left atrial strips from transgenic (TG4) mice with cardiac‐specific overexpression (∼200‐fold) of the β2 adrenoceptor (β2AR) were isolated, and their isometric force of contraction (Fc) in response to electrical stimulation was measured.
The βAR agonist isoprenaline elicited negative inotropic responses in all left atrial strips; in 6/11 preparations, it also had a small positive inotropic effect. This ‘up‐phase’ was observed from 0.1 to 10 nM, with the ‘down‐phase’ occurring at higher concentrations. Both phases were mediated by β2AR, as shown by their sensitivity to the β2AR antagonist ICI‐118,551 (100 nM; pA2 8.60±0.07, 8.45±0.19, for ‘up‐phase’ and ‘down‐phase,’ respectively), but not the β1AR antagonist CGP‐20712A (100 nM). Conversely, nontransgenic littermate preparations responded to isoprenaline treatment solely by an increase in Fc, which was β1AR‐mediated.
Pretreatment of left atrial strips with either 10 nM isoprenaline or 1 mM 8‐bromo‐cAMP significantly attenuated the TG4 ‘up‐phase’, while having no effect on either the TG4 ‘down‐phase’ or the littermate controls' responses. B. pertussis toxin treatment of the animals prevented isoprenaline's negative inotropic effects in TG4 preparations, but had no effect in littermate controls.
The findings imply that the responses of TG4 left atrium to isoprenaline are because of β2AR coupling to Gs and Gi proteins, consistent with the model of Daaka et al., in which protein kinase A phosphorylation of the β2AR causes a switch from Gs to Gi protein coupling.

British Journal of Pharmacology (2003) 138, 1358–1366. doi:10.1038/sj.bjp.0705191
Directional Harmonic Theory: A Computational Gestalt Model to Account for Illusory Contour and Vertex Formation
Authors: Lehar Steven 
Published: April 2003

Visual illusions and perceptual grouping phenomena offer an invaluable tool for probing the computational mechanism of low-level visual processing. Some illusions, like the Kanizsa figure, reveal illusory contours that form edges collinear with the inducing stimulus. This kind of illusory contour has been modeled by neural network models by way of cells equipped with elongated spatial receptive fields designed to detect and complete the collinear alignment. There are, however, other illusory groupings which are not so easy to account for in neural network terms. The Ehrenstein illusion exhibits an illusory contour that forms a contour orthogonal to the stimulus instead of collinear with it. Other perceptual grouping effects reveal illusory contours that exhibit a sharp corner or vertex, and still others take the form of vertices defined by the intersection of three, four, or more illusory contours that meet at a point. A direct extension of the collinear completion models to account for these phenomena tends towards a combinatorial explosion, because it would suggest cells with specialized receptive fields configured to perform each of those completion types, each of which would have to be replicated at every location and every orientation across the visual field. These phenomena therefore challenge the adequacy of the neural network approach to account for these diverse perceptual phenomena. I have proposed elsewhere an alternative paradigm of neurocomputation in the harmonic resonance theory (Lehar 1999, see website), whereby pattern recognition and completion are performed by spatial standing waves across the neural substrate. The standing waves perform a computational function analogous to that of the spatial receptive fields of the neural network approach, except that, unlike that paradigm, a single resonance mechanism performs a function equivalent to a whole array of spatial receptive fields of different spatial configurations and of different orientations, and thereby avoids the combinatorial explosion inherent in the older paradigm. The present paper presents the directional harmonic model, a more specific development of the harmonic resonance theory, designed to account for specific perceptual grouping phenomena. Computer simulations of the directional harmonic model show that it can account for collinear contours as observed in the Kanizsa figure, orthogonal contours as seen in the Ehrenstein illusion, and a number of illusory vertex percepts composed of two, three, or more illusory contours that meet in a variety of configurations.
Physical and psychosocial risk factors for lateral epicondylitis: a population based case-referent study
Authors: Haahr J P , Andersen J H 
Published: April 2003

Aims:To assess the importance of physical and psychosocial risk factors for lateral epicondylitis (tennis elbow).Methods:Case-referent study of 267 new cases of tennis elbow and 388 referents from the background population enrolled from general practices in Ringkjoebing County, Denmark.Results:Manual job tasks were associated with tennis elbow (odds ratio (OR) 3.1, 95% confidence interval (CI) 1.9 to 5.1). The self reported physical risk factors “posture” and “forceful work” were related to tennis elbow. Among women, work involving performing repeated movements of the arms was related to tennis elbow (OR 3.7, CI 1.7 to 8.3). Among men, work with precision demanding movements was related to tennis elbow (OR 5.2, CI 1.5 to 17.9). Among both males and females, the results for work with hand held vibrating tools were inconsistent, partly because of few exposed subjects. A physical strain index was established based on posture, repetition, and force. The adjusted ORs for tennis elbow at low, medium, and high strain were 1.4 (CI 0.8 to 2.7), 2.0 (CI 1.1 to 3.7), and 4.4 (CI 2.3 to 8.7). Low social support at work, adjusted for physical strain, was a risk factor among women (OR 2.4, CI 1.3 to 4.6).Conclusion:Results indicate that being a new case of tennis elbow is associated with non-neutral postures of hands and arms, use of heavy hand held tools, and high physical strain measured as a combination of forceful work, non-neutral posture of hands and arms, and repetition. Furthermore, tennis elbow among women was associated with low social support at work. The results for precision demanding movements and for vibration were less consistent.
Residential and occupational exposure to 50 Hz magnetic fields and malignant melanoma: a population based study
Authors: Tynes T , Klæboe L , Haldorsen T 
Published: April 2003

Aims:To test the hypothesis that exposure to electromagnetic fields from high voltage power lines increases the incidence of cutaneous malignant melanoma in adults aged 16 and above.Methods:Nested case-control study. The study population comprised subjects aged 16 and above who had lived in a residence situated in a broad corridor around a high voltage power line in 1980, or one of the years from 1986 to 1996. The cases were incident cases that were diagnosed in 1980–96 and reported to the Cancer Registry of Norway. Two controls were matched to each case by year of birth, sex, municipality, and first year entering the cohort. Time weighted average exposure to residential magnetic fields generated by the power lines was calculated for the exposure follow up from 1 January 1967 until diagnosis by means of a computer program, in which distance from residency to the line, line configuration, and current load were taken into account. Exposure was analysed using cut off points at 0.05 and 0.2 microtesla (μT). Exposure to magnetic fields at work was classified by an expert panel who assessed magnetic field exposure by combining branch and occupation into one of three levels: <4 hours, 4–24 hours, and >24 hours per week above background (0.1 μT). The categories were cumulated over the occupationally active years for the exposure follow up from 1 January 1955 until diagnosis, and cut off points at 18 and 31 category-years were evaluated.Results:Analysis of the two upper residential magnetic field categories showed an odds ratio of 2.01 (95% CI 1.09 to 3.69) and 2.68 (95% CI 1.43 to 5.04) for women, and an odds ratio of 1.70 (95% CI 0.96 to 3.01) and 1.37 (95% CI 0.77 to 2.44) for men, respectively. Occupational exposure showed no significant association with cutaneous malignant melanoma, and analysis of both residential and occupational exposure simultaneously, showed no additional effect.Conclusion:The present study provides some support for an association between exposure to calculated residential magnetic fields and cutaneous malignant melanoma, but because of the lack of a biological hypothesis and the known strong association between solar radiation and melanoma, no firm conclusions can be drawn and further studies would be of interest.
Return to work of cancer survivors: a prospective cohort study into the quality of rehabilitation by occupational physicians
Authors: Verbeek J , Spelten E , Kammeijer M , Sprangers M 
Published: April 2003

Aims:To describe and assess the quality of rehabilitation of cancer survivors by occupational physicians and to relate the quality of the process of occupational rehabilitation to the outcome of return to work.Methods:One hundred occupational physicians of a cohort of cancer survivors were interviewed about return to work management. Quality of rehabilitation was assessed by means of four indicators that related to performance in knowledge of cancer and treatment, continuity of care, patients complaints, and relations at work. The cohort of patients was prospectively followed for 12 months to assess time to return to work and rate of return to work. Patients’ and physicians’ satisfaction with care was also assessed. The relation between performance and these outcome measures was studied in a multivariate analysis, taking into account the influence of other work and disease related factors that could potentially predict return to work.Results:For knowledge of cancer and treatment, only 3% had optimal performance because occupational physicians did not communicate with treating physicians. For continuity of care, patient complaints, and relations at work, performance was optimal for 55%, 78%, and 60% of the physicians respectively. After adjustment for other prognostic factors, overall physician’s performance (hazard ratio (HR) 0.5, 95% CI 0.3 to 0.8) and continuity of care (HR 0.5, 95% CI 0.3 to 0.9) were related to the return to work of patients. Overall optimal performance was also related to a small but significant higher level of satisfaction with care, both for patients and physicians.Conclusion:Quality of occupational rehabilitation of cancer survivors can be improved substantially, especially with regard to communication between physicians and continuity of care. There is a need for the development of more effective rehabilitation procedures which should be evaluated in a randomised controlled trial.
ANALYSIS OF NEUTRINO OSCILLATION IN THREE-FLAVOR NEUTRINOS
Authors: SAKAI T. , INAGAKI O. , TESHIMA T. 
Published: April 2003

We analyze the solar, terrestrial and atmospheric neutrino experiments including SuperKamiokande data using the three-flavor neutrinos framework and obtain the allowed region for parameters [Formula: see text]. In solar neutrino experiments, we obtain the large angle solution [Formula: see text] and small angle solution (3×10-6-1.2×10-5 eV 2, 0.003-0.01) for θ13=0°-20°. From the terrestrial and atmospheric neutrino experiments including the sub-GeV and multi-GeV zenith angle dependence in SuperKamiokande 535 days data, we found that the νμ-ντ mixing is large and the range of [Formula: see text] as 0.02~0.0002 eV 2. There is no significant difference between large θ12 angle solution and small one.
Tenofovir Disoproxil Fumarate
Authors: Grim Shellee A , Romanelli Frank 
Published: April 2003

OBJECTIVE: To review the pharmacology, virology, pharmacokinetics, efficacy, safety, resistance profile, and clinical use of tenofovir disoproxil fumarate. DATA SOURCES: A MEDLINE search was performed (1966–August 2002) using the following terms: tenofovir, tenofovir disoproxil fumarate, PMPA (9-( R)-[2-(phosphonomethoxy)propyl]adenine), and Viread. Abstracts from HIV-related meetings were reviewed. DATA EXTRACTION AND STUDY SELECTION: Publications and meeting abstracts regarding tenofovir were reviewed. The most recent and pertinent items were included. DATA SYNTHESIS: Tenofovir disoproxil fumarate is a nucleotide prodrug that is diphosphorylated to its active moiety, tenofovir diphosphate. In this form, tenofovir acts as a reverse transcriptase inhibitor to inhibit HIV-1 replication. In clinical trials, tenofovir was effective at suppressing HIV-1 RNA and boosting CD4+ cell counts. Tenofovir has a long intracellular half-life, which permits once-daily dosing. Since tenofovir does not interact with the cytochrome P450 pathway, it exhibits minimal drug interactions, with the exception of didanosine. Compared with other reverse transcriptase inhibitors, tenofovir may have advantages in terms of toxicity and medication adherence profiles. Ongoing studies are also analyzing tenofovir's activity against hepatitis B virus. CONCLUSIONS: Tenofovir has been shown to be active against HIV-1 in combination with other antiretrovirals. The drug's benefit as a single-agent intensifier of highly active antiretroviral therapy in treatment-experienced patients has been established, and preliminary data for treatment-naïve patients are encouraging.
Direct extrusion of polymer latex emulsions
Authors: Nichols Russell J. , Senn Richard K. , Kheradi Farokh 
Published: April 2003

AbstractThe synthesis of many thermoplastic and elastomeric polymers can be accomplished by dispersing the monomer (or a blend of monomers) to be polymerized in water with the aid of various surfactants. The monomer is then polymerized by the introduction of a free radical catalyst to produce a latex of the polymer. Coagulation is the first step in isolating the polymer from the latex, and typically, many subsequent process steps are required to “finish” the polymer to the pelletized or expanded crumb from suitable for end users to convert the polymer into useful products.The process described herein combines all the process steps required to coagulate, separate and dewater, wash, devolatilize, homogenize and pump the polymer in a single‐step, short residence time system. The machine employed for this process is a counter‐rotating, tangentially opposed twin‐screw extruder. One important variation of the basic process combines an integral plasticating extrusion step with the latex conversion to make polymer blends and alloys. Critical process parameters are identified and discussed and examples of pilot plant scale experimental data for ABS (acrylonitrile‐butadiene‐styrene terpolymer) systems are reviewed.
The thermal conductivity and diffusivity of polyethylene solids and melts
Authors: Kamal Musa R. , Tan Victor , Kashani Farzad 
Published: April 2003

AbstractA miniaturized version of a recently developed apparatus has been constructed to measure both the thermal conductivity and thermal diffusivity of polymer melts and solids. The apparatus was employed to measure the thermal conductivity and diffusivity of a number of polyethylene resins of varying density and molecular weight distribution. The results obtained with the miniaturized unit are in good agreement with those obtained with the original larger apparatus. Moreover, the dependence of thermal conductivity and diffusivity on temperature, resin density, and molecular weight parameters has been evaluated with the aid of the new apparatus. Empirical relationships involving the quantity (MwMn)1/2 have been found for the dependence of thermal conductivity and diffusivity on molecular weight.
The distribution of number of passes over the flights in single screw melt extruders
Authors: Manas‐Zloczower I. , Tadmor Z. 
Published: April 2003

AbstractIn single screw melt extruders there is a continuous flow of polymer melt over the flight clearance. The melt flowing over the clearance experiences high shear rate and may also experience very high temperature. This, in turn, may affect polymer structure and properties. The melt that flows over the flight is mixed with the bulk of the melt flowing in the channel. In the extrudate there are fluid elements that have not passed over the flights and there are fluid elements that passed over the flight once, twice, or many times. In this paper, a theoretical model is proposed for calculating the number of pass distribution function of a melt stream emerging from a melt extruder.