bluuebunny/crossref_metadata_2025_split huggingface dataset:
An exploratory instrumental variable analysis of the outcomes of localized breast cancer treatments in a medicare population
Authors: Hadley Jack , Polsky Daniel , Mandelblatt Jeanne S. , Mitchell Jean M. , Weeks Jane C. , Wang Qin , Hwang Yi‐Ting ,   OPTIONS Research Team
Published: March 2003

AbstractThis study is motivated by the potential problem of using observational data to draw inferences about treatment outcomes when experimental data are not available. We compare two statistical approaches, ordinary least‐squares (OLS) and instrumental variables (IV) regression analysis, to estimate the outcomes (three‐year post‐treatment survival) of three treatments for early stage breast cancer in elderly women: mastectomy (MST), breast conserving surgery with radiation therapy (BCSRT), and breast conserving surgery only (BCSO). The primary data source was Medicare claims for a national random sample of 2907 women (age 67 or older) with localized breast cancer who were treated between 1992 and 1994.Contrary to randomized clinical trial (RCT) results, analysis with the observational data found highly significant differences in survival among the three treatment alternatives: 79.2% survival for BCSO, 85.3% for MST, and 93.0% for BCSRT. Using OLS to control for the effects of observable characteristics narrowed the estimated survival rate differences, which remained statistically significant. In contrast, the IV analysis estimated survival rate differences that were not significantly different from 0. However, the IV‐point estimates of the treatment effects were quantitatively larger than the OLS estimates, unstable, and not significantly different from the OLS results. In addition, both sets of estimates were in the same quantitative range as the RCT results.We conclude that unadjusted observational data on health outcomes of alternative treatments for localized breast cancer should not be used for cost‐effectiveness studies. Our comparisons suggest that whether one places greater confidence in the OLS or the IV results depends on at least three factors: (1) the extent of observable health information that can be used as controls in OLS estimation, (2) the outcomes of statistical tests of the validity of the instrumental variable method, and (3) the similarity of the OLS and IV estimates. In this particular analysis, the OLS estimates appear to be preferable because of the instability of the IV estimates. Copyright © 2002 John Wiley & Sons, Ltd.
High‐frequency oscillation in the hippocampus of the behaving rat and its modulation by the histaminergic system
Authors: Knoche A. , Yokoyama H. , Ponomarenko A. , Frisch C. , Huston J. , Haas H.L. 
Published: March 2003

AbstractThe histaminergic neurons located in the posterior hypothalamus modulate whole brain activity in a manner dependent on behavioral state. We have investigated their influence on high‐frequency oscillation (200‐Hz ripples) in the hippocampal CA1 region of freely moving rats. The occurrence of these ripples, assumed to be involved in memory trace formation, was markedly enhanced after injection of the H1‐antagonists pyrilamine and ketotifen in a lateral ventricle, indicating a tonic activity of the histaminergic system. The H2‐ and H3‐antagonists cimetidine and thioperamide were ineffective. We suggest a mediation of these effects through blocking the known histaminergic excitation of septal neurons. Histamine administered by the intracerebroventricular route had an inhibitory action on ripples. H1‐receptor activation, which has been shown to inhibit learning and memory, thus shifts hippocampal activity away from high‐frequency oscillation toward theta activity. Hippocampus 2003;13:273–280. © 2003 Wiley‐Liss, Inc.
Navigation expertise and the human hippocampus: A structural brain imaging analysis
Authors: Maguire Eleanor A. , Spiers Hugo J. , Good Catriona D. , Hartley Tom , Frackowiak Richard S.J. , Burgess Neil 
Published: March 2003

AbstractGrey matter volume in the posterior hippocampus of London taxi drivers is greater than in age‐matched controls, and the size of this increase correlates positively with time spent taxi driving (E.A. Maguire et al., 2000. Proc Natl Acad Sci U S A 97: 4398–4403). This change suggests that increased posterior hippocampal grey matter volume is acquired in response to increased taxi driving experience, perhaps reflecting their detailed representation of the city. However, an alternate hypothesis is that the difference in hippocampal volume is instead associated with innate navigational expertise, leading to an increased likelihood of becoming a taxi driver. To investigate this possibility, we used structural brain imaging and voxel‐based morphometry (VBM) to examine a group of subjects who were not taxi drivers. Despite this group showing a wide range of navigational expertise, there was no association between expertise and posterior hippocampal grey matter volume (or, indeed, grey matter volume throughout the brain). This failure to find an association between hippocampal volume and navigational expertise thus suggests that structural differences in the human hippocampus reflect the detail and/or duration of use of the spatial representation acquired, and not innate navigational expertise per se. Hippocampus 2003;13:250–259. © 2003 Wiley‐Liss, Inc.
Direct Spectroscopic Evidence that the Photochemical Outcome of Flutamide in a Protein Environment is Tuned by Modification of the Molecular Geometry: A Comparison with the Photobehavior in Cyclodextrin and Vesicles
Authors: Sortino Salvatore , Petralia Salvatore , Condorelli Giuseppe , Marconi Giancarlo 
Published: March 2003

AbstractThe photoreactivity of the phototoxic anticancer drug flutamide (FM) in the presence of bovine serum albumin (BSA) has been investigated. The presence of BSA induces a remarkable modification of the photochemical outcome of the drug with respect to that observed in aqueous solution. Induced circular dichroism (ICD) measurements combined with theoretical calculations provide strong evidence that the new photochemical scenario is tuned by changes of the molecular geometry of FM when incorporated in the protein microenvironment. This behavior presents close analogies to that found in the presence of either cyclodextrin or phospholipid vesicles, chosen as models for biological systems, and delineates a quite general photochemical picture that can be useful for a more appropriate understanding of the adverse phototoxic effects induced by this drug.
New Acetylcholinesterase‐Inhibitory Pregnane Glycosides of Cynanchum atratum Roots
Authors: Lee Ki Yong , Sung Sang Hyun , Kim Young Choong 
Published: March 2003

AbstractThree new pregnane glycosides, cynatroside A (1), cynatroside B (2), and cynatroside C (3), isolated from the roots of Cynanchum atratum (Asclepiadaceae), were characterized as 7β‐{[O‐α‐L‐cymaropyranosyl‐(1→4)‐O‐β‐D‐digitoxopyranosyl‐(1→4)‐β‐D‐oleandropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐6α‐hydroxy‐4b‐ methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one (1), 7β‐{[O‐β‐D‐cymaropyranosyl‐(1→4)‐O‐α‐L‐diginopyranosyl‐(1→4)‐β‐D‐cymaropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐2,6α‐dihydroxy‐4b‐methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one (2), and 7β‐{[O‐α‐L‐cymaropyranosyl‐(1→4)‐O‐β‐D‐digitoxopyranosyl‐(1→4)‐β‐L‐cymaropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐2,6α‐dihydroxy‐4b‐methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one (3), respectively. In addition, ten known constituents were identified, i.e., cynascyroside D (4), glaucoside C (5), glaucoside D (6), atratoside A (7), 2,4‐dihydroxyacetophenone (8), 4‐hydroxyacetophenone (9), syringic acid (10), azelaic acid (11), suberic acid (12), and succinic acid (13). Among these compounds, 1–4 significantly inhibit acetylcholinesterase activity.
Probes for Narcotic Receptor Mediated Phenomena
Authors: Linders Joannes T. M. , Mirsadeghi Seid , Flippen‐Anderson Judith L. , George Clifford , Jacobson Arthur E. , Rice Kenner C. 
Published: March 2003

AbstractThe synthesis of a series of epoxy 5‐phenylmorphans is being explored in order to determine the conformational requirements of the phenolic ring in a phenylmorphan molecule that may be needed both for binding to a specific opioid receptor and for exhibiting opioid agonist or antagonist activity. Of the twelve possible ortho‐ and para‐bridged isomers (a–f) (Fig. 1), we now report the synthesis of the para‐d isomer, rac‐(3R,6aS,11aR)‐2‐methyl‐1,3,4,5,6,11a‐hexahydro‐2H‐3,6a‐methanobenzofuro[2,3‐c]azocin‐8‐ol (3). Compound 3 was synthesized via construction of the 5‐phenylazabicyclo[3.3.1]non‐3‐ene skeleton (Scheme 1) and subsequent closure of the epoxy bridge (Scheme 2). As determined by an X‐ray diffraction study, the epoxy bridge, restricting the phenyl‐ring rotation, fixed the dihedral angle between the least‐squares planes through the phenyl ring and atoms N(2), C(3), C(11a), and C(6a) of the piperidine ring (Fig. 2) at 43.0°, and the torsion angle C(12)C(6a)C(6b)C(10a) at −95.0°.
New Acylated Preatroxigenin Saponins from Atroxima congolana
Authors: Elbandy Mohamed , Miyamoto Tomofumi , Delaude Clément , Lacaille‐Dubois Marie‐Aleth 
Published: March 2003

AbstractEight new acylated preatroxigenin saponins 1–8 were isolated as four inseparable mixtures of the trans‐ and cis‐4‐methoxycinnamoyl derivatives, atroximasaponins A1/A2 (1/2), B1/B2 (3/4), C1/C2 (5/6) and D1/D2 (7/8) from the roots of Atroxima congolana. These compounds are the first examples of triterpene saponins containing preatroxigenin (=(2β,3β,4α,22β)‐2,3,22,27‐tetrahydroxyolean‐12‐ene‐23,28‐dioic acid as aglycone. Their structures were elucidated on the basis of extensive 1D‐ and 2D‐NMR studies and FAB‐MS as 3‐O(β‐D‐glucopyranosyl)preatroxigenin 28‐{O‐β‐D‐xylopyranosyl‐(1→4)‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐O‐[O‐β‐D‐glucopyranosyl‐(1→3)‐β‐D‐glucopyranosyl‐(1→3)]‐4‐O‐(trans‐4‐methoxycinnamoyl)‐β‐D‐fucopyranoyl} ester (1) and its cis‐isomer 2, 3‐O‐(β‐D‐glucopyranosyl)preatroxigenin 28‐{O‐β‐D‐xylopyranosyl‐(1→4)‐O‐α‐L‐rhamnopyranosyl‐(1→ 2)‐O‐[O‐6‐O‐acetyl‐β‐D‐glucopyranosyl‐(1→3)‐β‐D‐glucopyranosyl‐(1→3)]‐4‐O‐(trans‐ 4‐methoxycinnamoyl)‐β‐D‐fucopyranosyl} ester (3) and its cis‐isomer 4, 3‐O‐(β‐D‐glucopyranosyl)preatroxigenin 28‐{O‐β‐D‐xylopyranosyl‐(1→4)‐O‐[β‐D‐apiofuranosyl‐(1→3)]‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐O‐[O‐6‐ O‐acetyl‐β‐D‐glucopyranosyl‐(1→3)‐β‐D‐glucopyranosyl‐(1→3)]‐4‐O‐(trans‐4‐methoxycinnamoyl)‐β‐D‐fucopyranoyl} ester (5) and its cis‐isomer 6, 3‐O‐(β‐D‐glucopyranosyl)preatroxigenin 28‐{O‐β‐D‐xylopyranosyl‐(1→4)‐O‐[β‐D‐apiofuranosyl‐(1→3)]‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐O‐[O‐β‐D‐xylopyranosyl‐(1→3)‐β‐D‐glucopyranosyl‐(1→3)]‐4‐O‐(trans‐4‐methoxycinnamoyl)‐β‐D‐fucopyranosyl ester (7) and its cis‐isomer 8.
The impact of financial constraints and incentives on professional autonomy
Authors: Lewis Jenny M. , Marjoribanks Tim 
Published: March 2003

AbstractGeneral practice has been the subject of extensive reforms over the 1990s in Australia as elsewhere. Reforms have attempted to improve quality and contain the overall cost of health care, and have often been seen as reducing the autonomy of medical professionals. This paper examines the impact of financial constraints and incentives introduced during the 1990s on Australian GPs' perceptions of autonomy. An existing seven component definition of autonomy and six themes that emerged from reviewing publications were used to construct focus group questions. A total of 25 GPs participated in four focus groups. Those who participated believe that their financial autonomy has been diminished by policy changes and consumer expectations. They also perceive that their ability to control clinical decisions, which they regard as the most important aspect of professional autonomy, has been reduced along with financial autonomy. Organized medicine in Australia sees financial accountability and clinical decision making as polar opposites, and has continued to argue that fee‐for‐service payment is the only appropriate method of remuneration, despite increasing evidence that this does not guarantee clinical autonomy. Major changes to the financing of general practice in Australia are required to address the concerns of GPs, governments and patients. Copyright © 2003 John Wiley & Sons, Ltd.
Numerical simulation of overbank processes in topographically complex floodplain environments
Authors: Nicholas A. P. , Mitchell C. A. 
Published: March 2003

AbstractThis article presents results from an investigation of the hydraulic characteristics of overbank flows on topographically‐complex natural river floodplains. A two‐dimensional hydraulic model that solves the depth‐averaged shallow water form of the Navier–Stokes equations is used to simulate an overbank flow event within a multiple channel reach of the River Culm, Devon, UK. Parameterization of channel and floodplain roughness by the model is evaluated using monitored records of main channel water level and point measurements of floodplain flow depth and unit discharge. Modelled inundation extents and sequences are assessed using maps of actual inundation patterns obtained using a Global Positioning System, observational evidence and ground photographs. Simulation results suggest a two‐phase model of flooding at the site, which seems likely to be representative of natural floodplains in general. Comparison of these results with previous research demonstrates the complexity of overbank flows on natural river floodplains and highlights the limitations of laboratory flumes as an analogue for these environments. Despite this complexity, frequency distributions of simulated depth, velocity and unit discharge data closely follow a simple gamma distribution model, and are described by a shape parameter (α) that exhibits clear systematic trends with changing discharge and floodplain roughness. Such statistical approaches have the potential to provide the basis for computationally efficient flood routing and overbank sedimentation models. Copyright © 2002 John Wiley & Sons, Ltd.
A tracer‐based assessment of hydrological pathways at different spatial scales in a mesoscale Scottish catchment
Authors: Soulsby C. , Rodgers P. , Smart R. , Dawson J. , Dunn S. 
Published: March 2003

AbstractGeochemically based hydrograph separation techniques were used in a preliminary assessment to infer how runoff processes change with landscape characteristics and spatial scale (1–233 km2) within a mesoscale catchment in upland Scotland. A two‐component end‐member mixing analysis (EMMA) used Gran alkalinity as an assumed conservative tracer. Analysis indicated that, at all scales investigated, acidic overland flow and shallow subsurface storm flows from the peaty soils covering the catchment headwaters dominated storm runoff generation. The estimated groundwater contribution to annual runoff varied from 30% in the smallest (ca 1 km2) peat‐dominated headwater catchment with limited groundwater storage, to >60% in larger catchments (>30 km2) with greater coverage of more freely draining soils and more extensive aquifers in alluvium and other drift. This simple approach offers a useful, integrated conceptualization of the hydrological functioning in a mesoscale catchment, which can be tested and further refined by focused modelling and process‐based research. However, even as it stands, the simple conceptualization of system behaviour will have significant utility as a tool for communicating hydrological issues in a range of planning and management decisions. Copyright © 2002 John Wiley & Sons, Ltd.
The hydrochemistry of Lake Vostok and the potential for life in Antarctic subglacial lakes
Authors: Siegert Martin J. , Tranter Martyn , Ellis‐Evans J. Cynan , Priscu John C. , Berry Lyons W. 
Published: March 2003

AbstractOur understanding of Lake Vostok, the huge subglacial lake beneath the East Antarctic Ice Sheet, has improved recently through the identification of key physical and chemical interactions between the ice sheet and the lake. The north of the lake, where the overlying ice sheet is thickest, is characterized by subglacial melting, whereas freezing of lake water occurs in the south, resulting in ∼210 m of ice accretion to the underside of the ice sheet. The accreted ice contains lower concentrations of the impurities normally found in glacier ice, suggesting a net transfer of material from meltwater into the lake. The small numbers of microbes found so far within the accreted ice have DNA profiles similar to those of contemporary surface microbes. Microbiologists expect, however, that Lake Vostok, and other subglacial lakes, will harbour unique species, particularly within the deeper waters and associated sediments. The extreme environments of subglacial lakes are characterized by high pressures, low temperatures, permanent darkness, limited nutrient availability, and oxygen concentrations that are derived from the ice that provides the meltwater. Copyright © 2002 John Wiley & Sons, Ltd.
Electrochemical deposition of hydroxyapatite with vinyl acetate on titanium implants
Authors: Hu Haobing , Lin Changjian , Lui Pauline Po Yee , Leng Yang 
Published: March 2003

AbstractA novel approach to electrochemical processing of hydroxyapatite (HA) coating was explored. Vinyl acetate was added in the electrolytes of calcium and phosphorous in order to improve the adhesion between HA coating and titanium substrate. X‐ray powder diffractometer (XRD) spectra indicated that the vinyl acetate did not interfere with the deposition of HA on the surface of titanium cathodes. X‐ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) results revealed that both vinyl acetate and HA were deposited on the titanium cathodes. The vinyl acetate changed the HA crystalline morphology in the deposition layer. The shape and growth direction of the HA crystals in the coating with vinyl acetate differed from those of HA deposition along. The addition of vinyl acetate increased the coating strength considerably, even though further improvement is needed for clinical applications. Moreover, a preliminary study of the bioactivity showed that osteoblastic cells exhibited higher cell proliferation potential on the HA/vinyl acetate coating than on that of pure HA. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 24–29, 2003
Comparative evaluation of the osteoinductivity of two formulations of human demineralized bone matrix
Authors: Takikawa Satoshi , Bauer Thomas W. , Kambic Helen , Togawa Daisuke 
Published: March 2003

AbstractIn the United States, demineralized bone matrix (DBM) is considered a transplantable tissue and therefore is regulated primarily by the American Association of Tissue Banks. Even though DBM is not subjected to the same regulations relative to performance claims as medical devices are, one would expect different processing methods might yield DBM preparations of different osteoinductive potential. The purpose of this study was to use an established athymic rat model to compare the osteoinductive properties of two commercially available human DBMs prepared using different methods but having essentially identical product claims. Sixteen female athymic rats were used to test equivalent volumes of two lots each of Grafton Putty® (Osteotech, Inc., Eatontown, NJ), Osteofil® (Regeneration Technologies, Inc., Alachua, FL), and rat DBM. At 28 days after implantation, qualitative and semiquantitative microscopy showed no significant differences in bone formation between the two lots from each source, but rat DBM produced significantly more bone than Grafton®, which produced significantly more bone than Osteofil®. Our results suggest that methods of graft processing may represent a greater source of variability than do differences among individual donors. Whether these differences relate to methods of demineralization, carrier, dose of DBM per volume, or to some other factor remains to be determined. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 37–42, 2003
In vivo bone response to porous calcium phosphate cement
Authors: del Real R. P. , Ooms E. , Wolke J. G. C. , Vallet‐Regí M. , Jansen J. A. 
Published: March 2003

AbstractWe conducted an in vivo experiment to evaluate the resorption rate of a calcium phosphate cement (CPC) with macropores larger than 100 μm, using the CPC called Biocement D (Merck Biomaterial, Darmstadt, Germany), which after setting only shows pores smaller than 1 μm. The gas bubble method used during the setting process created macroporosity. Preset nonporous and porous cement implants were inserted into the trabecular bone of the tibial metaphysis of goats. The size of the preset implants was 6 mm and the diameter of the drill hole was 6.3 mm, leaving a gap of 0.3 mm between implant surface and drill wall. After 2 and 10 weeks, the animals were euthanized and cement implants with surrounding bone were retrieved for histologic evaluation. Light microscopy at 2 weeks revealed that the nonporous implants were surrounded by connective tissue. On the cement surface, we observed a monolayer of multinucleated cells. Ten weeks after implantation, the nonporous implants were still surrounded by connective tissue. However, a thin layer of bone now covered the implant surface. No sign of cement resorption was observed. In contrast, the porous cement evoked a completely different bone response. At 2 weeks, bone formation had already occurred inside the implant porosity. Bone formation even appeared to occur as a result of osteoinduction. Also, at their outer surface, the porous implants were completely surrounded by bone. At 2 weeks, about 31% of the initial cement was resorbed. After 10 weeks, 81% of the initial phosphate cement was resorbed and new bone was deposited. On the basis of these observations, we conclude that the creation of macropores can significantly improve the resorption rate of CPC. This increased degradation is associated with almost complete bone replacement. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 30–36, 2003
The nature and dissemination of UHMWPE wear debris retrieved from periprosthetic tissue of THR
Authors: Elfick Alistair P. D. , Green Sarah M. , Krikler Steve , Unsworth Anthony 
Published: March 2003

AbstractThe role of wear debris in provoking joint replacement failure through bone resorption is now supported by much research. This study presents the analysis of 104 tissue samples using laser diffraction wear particle analysis in conjunction with standard histologic methods. The number and volume distributions were correlated to a range of joint and patient parameters. The median particle diameter by number was 0.69 μm. No particles smaller than 0.113 μm were resolved. No variation in terms of particle distribution was found among joint types. The ability of particles to migrate away from their point of origin was found to be inversely proportional to their size. The numbers of particles per gram of tissue found in various regions around the prosthesis varied little. Further, the numbers of particles in tissue samples shown to have a chronic foreign‐body reaction was > 1 × 109 particles/gram. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 95–108, 2003