bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of solute release from polymeric monoliths subject to linear structural relaxation
Authors: Papadokostaki K. G. , Polishchuk A. Ya. , Petrou J. K. 
Published: August 2002

AbstractA previously developed model of solute release from a swellable polymeric matrix induced by solvent uptake that obeys Fickian kinetics is here extended to cover the case of non‐Fickian solvent uptake caused by slow structural relaxation of the swelling polymer. For this purpose, we have adopted a model description of the absorption process (also previously developed in our laboratory), which has been shown to be capable of realistically simulating a wide range of non‐Fickian kinetics (including the well‐known two‐stage sorption and case II regimes). The aforementioned structural relaxation phenomena constitute important characteristics of glassy polymeric matrices. Accordingly, the predictions of the resulting combined model have been investigated in some detail in this series of articles. This particular article is concerned with the simplest version of the model, involving constant uptake kinetic parameters (diffusion coefficient and relaxation frequency) for both osmotically inactive and osmotically active solutes. Emphasis is put on possibilities of achieving and sustaining nearly constant release rates, and it is shown that such possibilities are considerably more numerous here than under conditions of Fickian solvent uptake kinetics. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1171–1188, 2002
Formation of junction zones in thermoreversible methylcellulose gels
Authors: Takahashi Masae , Shimazaki Masako 
Published: August 2002

AbstractTo analyze the structure of junction zones formed in methylcellulose (MC) gel, the modified Eldridge–Ferry method was applied to phase diagrams for aqueous solutions of different molecular weight MCs derived from micro‐DSC, small‐angle X‐ray scattering, and visual inspection. The results suggested that junctions in MC gels took thin, rodlike fringed‐micellar crystallites. The junction multiplicity s decreased from 4.3 for low‐temperature melting gels to 2.0 for high‐temperature melting gels. With increasing molecular weight, the number ζ of statistical units in a junction along a single chain increased from 27 to 54. Because the number depends sensitively on the enthalpy of bonding per mole of the repeat units of MC, our estimate is considered to give an upper bound to the junction length. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 943–946, 2001
Development of oriented structure and properties on drawing of poly(vinylidene fluoride) by solid‐state coextrusion
Authors: Nakamura Koh , Nagai Masayuki , Kanamoto Tetsuo , Takahashi Yoshiyuki , Furukawa Takeo 
Published: August 2002

AbstractGel films of poly(vinylidene fluoride) (PVDF) consisting of α‐form crystals were drawn uniaxially by solid‐state coextrusion to extrusion draw ratios (EDR) up to 9 at an optimum extrusion temperature of 160 °C, about 10°C below the melting temperature (Tm). The development of an oriented structure and mechanical and electrical properties on coextrusion drawing were studied as a function of EDR. Wide‐angle X‐ray diffraction patterns showed that the α crystals in the original gel films were progressively transformed into oriented β‐form crystals with increasing EDR. At the highest EDR of 9 achieved, the drawn product consisted of a highly oriented fibrous morphology with only β crystals even for the draw near the Tm. The dynamic Young's modulus along the draw direction also increased with EDR up to 10.5 GPa at the maximum EDR of 9. The electrical properties of ferroelectricity and piezoelectricity were also markedly enhanced on solid‐state coextrusion. The D–E square hysteresis loop became significantly sharper with EDR, and a remanent polarization Pr of 100 mC/m2 and electromechanical coupling factor along the thickness direction kt of 0.27 were achieved at the maximum EDR of 9. The crystallinity value of 73–80% for the EDR 9 film, estimated from these electrical properties, compares well with that calculated by the ratio of the crystallite size along the chain axis to the meridional small‐angle X‐ray scattering (SAXS) long period, showing the average thickness of the lamellae within the drawn β film. These results, as well as the appearance of a strong SAXS maximum, suggest that the oriented structure and properties of the β‐PVDF are better explained in terms of a crystal/amorphous series arrangement along the draw axis. Further, the mechanical and electrical properties obtained in this work are the highest among those ever reported for a β‐PVDF, and the latter approaches those observed for the vinylidene fluoride and trifluoroethylene copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1371–1380, 2001
Thermodynamic properties of dendrimers compared with linear polymers: General observations
Authors: Hay Grant , Mackay Michael E. , Hawker Craig J. 
Published: August 2002

AbstractThe pressure‐volume‐temperature and thermal properties of dendrimers based on benzyl ether were measured and compared with literature values for monodisperse, linear polystyrenes. In addition, property measurements are presented for an exact linear analogue to the fifth‐generation dendrimer. The thermodynamic properties' molecular weight behavior for the dendrimers is unique when compared with that of linear polystyrene. All of the evidence presented in this work suggests that some form of structural transition occurs in the bulk at a molecular mass near that for the fourth‐generation dendrimer. No such transition is seen for polystyrene. Dendrimers exhibit an increased packing efficiency as evidenced by a decreased specific volume (increased density) as compared with an exact linear analogue of the fifth‐generation dendrimer analogue, and the dendrimer highlights the entropic differences between the two molecules. In addition, differences in the change in heat capacity with temperature for the two systems further allude to their entropic differences. A crystalline state can be formed for the lower generation dendrimer and linear analogue. This crystalline state is not seen in dendrimers above the third generation. These behaviors compiled with the difference in the glass‐transition temperature for the linear analogue suggest that the dendrimers' microstructure has a significant influence on the bulk thermodynamic state of the material. The Tait equation was fitted to the volume data for comparative purposes; the Tait equation has known limitations but was selected because of its widespread application. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1766–1777, 2001
Preparation of polymer optical fibers doped with nonlinear optical active organic chromophores
Authors: Peng Gang‐Ding , Li Alexander D. Q. 
Published: August 2002

AbstractWe synthesized two novel organic nonlinear optical chromophores—chiral S(+)‐N‐[p‐(4‐nitrostyryl) phenyl] prolinol and non‐chiral [p‐(4‐nitrostyryl) phenyl] piperdine—as potential laser‐active dyes for photonic applications. Both materials show good optical transmittance in the telecommunication frequency region, desirable solubility in acrylic polymer optical fiber matrices, and attractive fluorescence properties that are advantageous for laser‐gain materials and devices. Subsequently, these two chromophores were incorporated into poly(methyl methacrylate) and poly(ethyl methacrylate) and drawn into polymer optical fibers. The relevant properties of these organic dye‐doped fibers have been studied, revealing essential attributes of laser‐active characteristics. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1794–1801, 2001
Stretched polymer surfaces: Atomic force microscopy measurement of the surface deformation and surface elastic properties of stretched polyethylene
Authors: Opdahl A. , Somorjai G. A. 
Published: August 2002

AbstractThe surface structure and surface mechanical properties of low‐ and high‐density polyethylene were characterized by atomic force microscopy (AFM) as the polymers were stretched. The surfaces of both materials roughened as they were stretched. The roughening effect is attributed to deformation of nodular structures, related to bulk spherulites, at the surface. The surface‐roughening effect is completely reversible at tensile strains in the elastic regime and partially reversible at tensile strains in the plastic regime until the polymers are irreversibly drawn into fibers. AFM force versus distance interaction curves, used to measure changes in the stiffness of the surface and the surface elastic modulus as a function of elongation, show that the surfaces become softer as the polymers are drawn into fibers at high strains. At low elastic strains, however, the surface elastic modulus of HDPE increases—attributed to elastic energy stored by the amorphous regions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2263–2274, 2001
Considerations in using tumor markers: what the psycho‐oncologist needs to know
Authors: Fertig Debra L. , Hayes Daniel F. 
Published: August 2002

AbstractTumor markers are measures of biological features of a cancer. By revealing important biological aspects of the tumor, tumor markers can be useful in staging patients, predicting cancer outcomes, and guiding treatments. The psychological consequences of using tumor markers are virtually unknown. In this review article, we draw on clinical studies involving the psychological impact of risk information, screening, prognostic information and surveillance of cancer. Such studies may be helpful in considering possible psychological reactions to tumor marker information in clinical practice. Copyright © 2001 John Wiley & Sons, Ltd.
Pulmonary function in technology‐dependent children 2 years and older with bronchopulmonary dysplasia*
Authors: Talmaciu Isaac , Ren Clement L. , Kolb Susan M. , Hickey Eileen , Panitch Howard B. 
Published: August 2002

AbstractSomatic and pulmonary growth coincide with resolution of hypoxemia by 2 years of age in most children with bronchopulmonary dysplasia (BPD). However, a distinct subgroup of children with BPD continue to require mechanical ventilation and/or supplemental oxygen beyond 2 years of age. This study tested the hypothesis that indices of pulmonary function would be significantly worse in children with BPD 2 years and older who remained technology‐dependent secondary to hypoxemia, compared to those of age‐matched children with BPD who were normoxemic. We measured pulmonary mechanics in 21 oxygen‐ or ventilator‐dependent children with BPD 2 years and older (BPDO2 group; mean age ± SD, 30.2 ± 6.5 months) and in 19 children with BPD who had been weaned off mechanical ventilation and supplemental oxygen for at least 6 months (control group; mean age, 30.1 ± 5.5 months). Respiratory rate and tidal volume were measured after sedation with chloral hydrate, and dynamic compliance and expiratory conductance were calculated using the esophageal catheter technique. Maximal flow at FRC (V′maxFRC) and ratio of forced‐to‐tidal flows at midtidal volume were obtained by the rapid thoracic compression technique. FRC was determined by nitrogen washout.There were no statistically significant differences in most measured indices of pulmonary mechanics between the BPDO2 and control groups. However, V′maxFRC/FRC was higher in controls compared to subjects in the BPDO2 group (0.81 ± 0.40 sec−1 vs. 0.34 ± 0.21 sec−1, P < 0.003).We conclude that most indices of pulmonary function in children with BPD 2 years and older do not reflect the need for mechanical ventilation or supplemental oxygen. We speculate that measurements of lung elastic recoil and tests of distribution of ventilation and pulmonary perfusion may be more sensitive in differentiating normoxemic and hypoxemic children with BPD 2 years and older. Pediatr Pulmonol. 2002; 33:181–188. © 2002 Wiley‐Liss, Inc.
Measurements of resistance by the interrupter technique and of transcutaneous partial pressure of oxygen in young children during methacholine challenge
Authors: Beydon Nicole , Trang‐Pham Ha , Bernard Agnès , Gaultier Claude 
Published: August 2002

AbstractMeasurement of bronchial airway responsiveness requires noninvasive techniques in young children. The study was designed to examine the changes in resistance as measured using the interrupter technique (Rint) at the dose of methacholine (M) that induced a fall in transcutaneous partial pressure in O2 (PtcO2) ≥ 20% (PD20PtcO2) in young children. Rint was calculated using the linear back‐extrapolation method (RintL) and the end‐interrupter method (RintEI). Twenty‐two children (mean age, 5.2 ± 1.1 years; range, 3.4 – 7.1 years) with nonspecific respiratory symptoms (mainly chronic cough, n = 17) were tested. PtcO2, RintL, and RintEI were measured before the test, after saline challenge (baseline (B)), after each dose of M delivered by a dosimeter, and after bronchodilator (BD) inhalation.PtcO2 decreased significantly during M challenge, from 85 ± 6 mmHg (B) to 62 ± 9 mmHg (P < 0.05), and increased after BD inhalation, to 82 ± 8 mmHg. RintL and RintEI increased significantly during M challenge, from 0.94 ± 0.2 KPa/L/s and 1.11 ± 0.19 KPa/L/s (B) to 1.27 ± 0.35 KPa/L/s and 1.47 ± 0.37 KPa/L/s, respectively (P < 0.05), and decreased after BD inhalation to 0.80 ± 0.17 KPa/L/s and 0.95 ± 0.18 KPa/L/s, respectively. Nineteen of 22 children reached the PD20PtcO2 at a dose of M ranging from 50–400 μg. At the PD20PtcO2, significant changes in RintL and RintEI (sensitivity index (SI) ≥ 2) were found in 79% and 63% of children, respectively.We conclude that: 1) M challenge using PtcO2 is safe in young children; and 2) our findings are not in favor of the use of Rint as the only indicator of bronchial reaction in young children during M challenge. Pediatr Pulmonol. 2001; 31:238–246. © 2001 Wiley‐Liss, Inc.
Albuterol delivery in a neonatal ventilated lung model: Nebulization versus chlorofluorocarbon‐ and hydrofluoroalkane‐pressurized metered dose inhalers*
Authors: Lugo Ralph A. , Kenney Julie K. , Keenan Jim , Salyer John W. , Ballard Julie , Ward Robert M. 
Published: August 2002

AbstractThe aim of this study was to compare albuterol delivery in a neonatal ventilated lung model, using three delivery methods: 1) jet nebulizer; 2) chlorofluorocarbon‐pressurized metered dose inhaler (CFC‐MDI) actuated into an ACE® spacer; and 3) hydrofluoroalkane‐pressurized MDI (HFA‐MDI) actuated into an ACE® spacer. The bench model consisted of a mechanically ventilated infant test lung with ventilator settings to simulate a very low birth weight neonate with moderate lung disease. Albuterol solution (0.5%) was nebulized at the humidifier and temperature port, 125 cm and 30 cm from the Y‐piece, respectively. Albuterol metered dose inhalers (MDIs) were actuated into an ACE® spacer that was tested in two positions: 1) inline between the endotracheal (ET) tube and the Y‐piece; and 2) attached to the ET tube and administered by manual ventilation. Albuterol was collected on a filter at the distal end of the ET tube and was quantitatively analyzed by high performance liquid chromatography.Albuterol delivery by CFC‐MDI (position 1, 4.8 ± 1.0%, vs. position 2, 3.8 ± 1.6%, P > 0.05) and HFA‐MDI (position 1, 5.7 ± 1.6%, vs. position 2, 5.5 ± 2.4%, P > 0.05) were significantly greater than delivery by nebulization at 30 cm (0.16 ± 0.07%) and 125 cm (0.15 ± 0.03%) from the Y‐piece (P < 0.001). A single actuation of albuterol MDI delivered the equivalent of nebulizing 2.5–3.7 mg of albuterol solution.We conclude that albuterol administered by MDI and ACE® spacer resulted in more efficient delivery than by nebulization in this mechanically ventilated neonatal lung model. There was no significant difference in drug delivery between CFC‐MDI and HFA‐MDI; nor did the placement of the spacer significantly affect drug delivery. Pediatr Pulmonol. 2001; 31:247–254. © 2001 Wiley‐Liss, Inc.
Physical effects of heliox versus oxygen on measurements of functional residual capacity by the nitrogen washout technique in small lung volumes: A model study
Authors: Hentschel Roland , Suska Andreas , Volbracht Andreas , Harms Erik , Haberland Hellmut , Jorch Gerhard 
Published: August 2002

AbstractMeasurements of functional residual capacity (FRC) by the nitrogen (N2) washout technique yield low N2 signals in neonates and preterm infants, especially when they are on high fractions of inspired oxygen (FiO2). Thus, recorded values often lie in the low range of detectability. We hypothesized that using heliox instead of oxygen as a washout gas would affect the electric discharge conditions of N2 molecules in a standard UV analyzer and thus yield higher N2 signals. We performed three laboratory experiments using conditions similar to those in neonates with pulmonary disease, reproducing different initial FiO2 values and very small lung volumes. Standard calibration procedures with physical models between 13.5–87 mL using a calibration syringe and purpose‐built small calibration cylinders were carried out, and washout gas was either pure oxygen (as is general practice) or heliox at different ratios.We observed that the calibration line with heliox was shifted upwards and the slope was increased, depending on helium concentration and initial FiO2. Since this effect was dose‐dependent with respect to the proportion of helium in the washout gas, this strongly suggests a physical process elicited by the noble gas helium.We conclude that the heliox wash‐out modification may help to increase the accuracy of FRC measurements and thus may enable studies of smaller patients or patients on high inspired FiO2. Pediatr Pulmonol. 2001; 31:255–260. © 2001 Wiley‐Liss, Inc.
Progressive lung and cardiac changes associated with pulmonary hypertension in the fetal rat
Authors: Fabris Viciany E. , Pato Mary D. , Belik Jaques 
Published: August 2002

AbstractTo determine the natural history of lung vascular remodeling and cardiac changes in the rat model of persistent pulmonary hypertension syndrome (PPHN) of the newborn, we studied fetal rats subjected to maternal indomethacin administration initiated on day 19 of gestation and continued for 2, 3, or 4 days. Animals receiving a similar volume of water or alcohol served as controls.Significant pulmonary hypertension was noted in the experimental group, as evidenced by a significantly increased right to left ventricular wall ratio to 1.6 ± 0.1 in the 4‐day treatment group, as compared with 1.2 ± 0.4 in the control group (P < 0.01). The smooth muscle area for <25 μm external diameter arterial vessels was significantly increased (12.7 ± 0.6 vs. 10.0 ± 0.6 μm; P < 0.01) and the adventitial area of all diameters vessels was significantly greater (P < 0.01) following 3 days of indomethacin treatment, as compared with water controls. Associated with these changes, the 4‐day treatment group's lung/body weight ratio was 0.021 ± 0.001, and was significantly less (P < 0.01) than for the control group (0.035 ± 0.001). This reduction in lung weight was not associated with changes in lung protein content or wet/dry weight ratio, indicating that pulmonary hypertension in the fetal rat induced lung hypoplasia.In conclusion, closure of the ductus arteriosus in the fetal rat results in early‐onset right ventricular hypertrophy, followed by pulmonary vascular remodeling and lung hypoplasia. We speculate that lung growth in late gestation is adversely affected by pulmonary hypertension. Pediatr Pulmonol. 2001; 31:344–353. © 2001 Wiley‐Liss, Inc.
Differential expression of interleukin‐15, a pro‐inflammatory cytokine and T‐cell growth factor, and its receptor in human prostate
Authors: Handisurya Alessandra , Steiner Georg E. , Stix Ursula , Ecker Rupert Ch. , Pfaffeneder‐Mantai Sabine , Langer Dina , Kramer Gero , Memaran‐Dadgar Nima , Marberger Michael 
Published: August 2002

AbstractBackgroundPro‐inflammatory interleukin (IL)‐15 plays a major role in host defense and chronic inflammation by stimulating T‐lymphocyte recruitment and growth. Expression of IL‐15 and IL‐15 receptor (IL‐15R) in human prostate was examined.MethodsNormal and benign hyperplastic (BPH) prostate specimens (n = 23) were analyzed for IL‐15 and IL‐15Rα‐chain expression by immunohistochemistry and Real‐Time‐PCR/RT‐PCR. Regulation of prostatic stromal cell (PSC) IL‐15 mRNA and effect of IL‐15 on prostatic cell growth were analysed in vitro.ResultsIn normal prostate, anti‐IL‐15 and anti‐IL‐15Rα‐chain reactivity were restricted to smooth muscle and stromal cells. However, in BPH, in addition epithelial cells frequently exhibited discrete anti‐IL‐15R and often intense, membranous anti‐IL‐15 reactivity. IL‐15/IL‐15R mRNA were detected in all prostatic cells types. In BPH tissues, IL‐15 mRNA content was variable (15‐fold). IL‐15 mRNA synthesis of PSC was significantly up‐regulated by IFN‐γ. Furthermore IL‐15 strongly stimulated the growth of BPH‐T‐lymphocytes and weakly that of carcinoma cell lines, but not of stromal cells.ConclusionsOverexpression of IL‐15 and IL‐15Rα‐chain in BPH and massive proliferation of BPH‐T‐lymphocytes induced by IL‐15 suggest a role for IL‐15 in prostatic inflammation. Since IFN‐γ, a T‐lymphocyte product, stimulates prostatic IL‐15 production; chronic inflammation might be triggered by this paracrine loop. Prostate 49:251–262, 2001. © 2001 Wiley‐Liss, Inc.
Melatonin and prostate cancer cell proliferation: Interplay with castration, epidermal growth factor, and androgen sensitivity
Authors: Siu Stephanie W.F. , Lau Kai W. , Tam Po C. , Shiu Stephen Y.W. 
Published: August 2002

AbstractBACKGROUNDPotential modulatory effects of melatonin on the proliferation of androgen‐sensitive LNCaP and androgen‐insensitive PC‐3 and DU 145 prostate cancer cells were reported recently. In this study, we investigated the effects of combined melatonin and castration on LNCaP tumor growth in vivo, the interactions between melatonin and epidermal growth factor (EGF) on LNCaP cell proliferation, and melatonin actions on the proliferation of PC‐3 and DU 145 cells.METHODSTumor development and growth in castrated nude mice inoculated with LNCaP cells or in intact animals inoculated with DU 145 cells, with or without daily melatonin treatment, were monitored by observation and caliper measurement. MT1 receptor expression in native or transfected prostate cancer cell lines was examined by immunocytochemistry or 2‐[125I]iodomelatonin binding. Cyclin D1 expression in LNCaP cells was assessed by Western blotting, and cell proliferation was measured by thymidine incorporation and/or cell count.RESULTSMelatonin treatment was associated with further decreases in LNCaP tumor incidence and growth rate in castrated nude mice. Melatonin and 2‐iodomelatonin (a melatonin receptor agonist) attenuated EGF‐stimulated increases in LNCaP cell proliferation and cyclin D1 levels. Melatonin had no effect on the proliferation or growth of MT1 receptor‐expressing DU 145 cells, and of PC‐3 cells in which MT1 receptor protein was undetectable. The proliferation of transfected PC‐3 cells expressing MT1 receptor was unaffected by 2‐iodomelatonin.CONCLUSIONTogether with previous data, the present results indicate synergistic action of melatonin and castration in inhibiting the growth of androgen‐sensitive LNCaP tumor. Androgen‐sensitive prostate cancer cell proliferation may be modulated by opposite changes in cyclin D1 levels induced by activated MT1 and EGF receptors. In androgen‐insensitive prostate cancer cells, MT1 receptor‐mediated signal transduction may become defective not only through changes in membrane receptor protein expression and/or functions, but also by means of alterations in downstream postreceptor signaling events. Prostate 52:106–122, 2002. © 2002 Wiley‐Liss, Inc.