bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of wet meadow riparian vegetation on streambank erosion. 1. Remote sensing measurements of streambank migration and erodibility
Authors: Micheli E. R. , Kirchner J. W.
Published: October 2002

We quantified how rates of stream channel migration in a montane meadow vary as a function of the riparian vegetation community. The South Fork of the Kern River at Monache Meadow, located in California's southern Sierra Nevada range, supports two distinct types of vegetation: a dry meadow community dominated by sagebrush and non‐native grasses (xeric scrub and meadow), and a wet meadow community dominated by rushes and sedges (hydric graminoids). We measured rates of lateral stream migration for dry versus wet meadow reaches from aerial photographs spanning a 40‐year period (1955–1995). While stream migration rates averaged only 0·24 ± 0·02 m a−1in the wet meadow, the dry meadow channel migrated an average of 1·4 ± 0·3 m a−1. We used a linear model of meander migration to calculate coefficients that characterize bank migration potential, or bank erodibility, independent of channel curvature. These calculations demonstrate that, at Monache Meadow, banks without wet meadow vegetation are roughly ten times more susceptible to erosion than banks with wet meadow vegetation. Where stream bank heights consistently exceed 1 m, low water availability creates riparian habitats dominated by dry meadow vegetation. Thus, channel incision may reduce bank stability not only by increasing bank height, but also by converting banks from wet meadow to dry meadow vegetation. Copyright © 2002 John Wiley & Sons, Ltd.
Thermal properties of gypsum plasterboard at high temperatures
Authors: Thomas Geoff
Published: October 2002

Light timber frame wall and floor assemblies typically use gypsum‐based boards as a lining to provide fire resistance. In order to model the thermal behaviour of such assemblies, the thermo‐physical properties of gypsum plasterboard must be determined. The relevant literature and the chemistry of the two consecutive endothermic dehydration reactions that gypsum undergoes when heated are reviewed. The values determined for the thermo‐physical properties are modified to create smooth enthalpy and thermal conductivity curves suitable for input into a finite element heat transfer model. These values are calibrated within a reasonable range and then validated using furnace and fire test data. The type of plasterboard used in these tests is an engineered product similar to the North American type C board. The temperature at which the second dehydration reaction occurs is altered to be consistent with later research with little apparent affect on the comparison with test results. Values for specific heat, mass loss rates and thermal conductivity for gypsum plasterboard that are suitable for use in finite element heat transfer modelling of light timber frame wall and floor assemblies are recommended. Copyright © 2002 John Wiley & Sons, Ltd.
The potential application of some novel essential oils as natural cosmetic preservatives in an aqueous cream formulation
Authors: Muyima N. Y. O. , Zulu G. , Bhengu T. , Popplewell D.
Published: October 2002

The use of essential oils in the production of cosmetics and related products may have several advantages, such as enhancing the dermato‐cosmetic properties and preservation, as well as the marketing image of the final product. The use of botanical materials such as essential oils in cosmetic formulations at relatively high concentrations is likely to provide skin benefit. The potential of essential oils indigenous to the tropical and subtropical part of Africa has not been sufficiently exploited in this regard. Using a challenge test, this study demonstrates the potential application of two South African indigenous plant essential oils, viz. Artemisia afra and Pteronia incana oils, and oils of two Mediterranean aromatic plants grown in South Africa, viz. Lavandula officinalis, and Rosmarinus officinalis, to be used as natural cosmetic preservatives in an aqueous cream formulation. Except for Pseudomonas aeruginosa strains, the oils displayed remarkable antimicrobial activities against all common test organisms (including bacteria and fungi) and environmental isolates used. All the test microorganisms used in this study were generally more susceptible to the oils during the challenge test in aqueous cream compared to the antimicrobial test performed on agar. The results indicate, therefore, that the oils can be recommended as candidate natural cosmetic preservatives. Artemisia afra oil was the most efficient in reducing the load of artificial contaminations in the aqueous cream formulation within 2–7 days. Since relatively high concentrations of the oils were used, the oils could at the same time serve as natural fragrances in aqueous cream, in addition to assuring protection against microbial contamination. Copyright © 2002 John Wiley & Sons, Ltd.
Implied volatility forecasts in the grains complex
Authors: Simon David P.
Published: October 2002

This article finds that the implied volatilities of corn, soybean, and wheat futures options 4 weeks before

option expiration have significant predictive power for the underlying futures contract return volatilities through

option expiration from January 1988 through September 1999. These implied volatilities also encompass the

information in out‐of‐sample seasonal Glosten, Jagannathan, and Runkle (GJR;1993)

volatility forecasts. Evidence also demonstrates that when corn‐implied volatility rises relative to

out‐of‐sample seasonal GJR volatility forecasts, implied volatility substantially overpredicts

realized volatility. However, simulations of trading rules that involve selling corn option straddles when

corn‐implied volatility is high relative to out‐of‐sample GJR volatility forecasts indicate

that none of the trading rules would have been significantly profitable. This finding suggests that these options

are not necessarily overpriced. © 2002 Wiley Periodicals, Inc. Jrl Fut Mark 22:959–981, 2002
The DSM‐IV ‘minor depression’ disorder in the oldest‐old: prevalence rate, sleep patterns, memory function and quality of life in elderly people of Italian descent in Southern Brazil
Authors: Xavier Flávio M. F. , Ferraza Marcos P. T. , Argimon Irani , Trentini Clarissa M. , Poyares Dalva , Bertollucci Paulo H. , Bisol Luisa W. , Moriguchi Emilio H.
Published: October 2002

Objectives

(1) To describe the prevalence of minor depression in a community‐dwelling population aged 80 years and over. (2) To compare the sleep pattern, memory function and the prevalence rate of other psychiatric diagnoses between normal controls and subjects with minor depressive disorder.

Design

A random representative sample (sample = 77 subjects/county population of oldest‐old = 219—35%) aged 80 years or more was selected from the county of Veranópolis in the Brazilian rural southern region. Of this group, eight subjects who met the DSM‐IV criteria for minor depression, and 50 subjects without diagnosed delirium disorder, cognitive or affective problems were compared.

Results

The prevalence rate of minor depression was 12%. Subjects with this diagnosis were more likely to complain about sleep and memory problems than elderly people without any other affective disorder (major depression or dysthymic disorder). Otherwise, objective evaluation of these two areas, memory and sleep, did not show differences between the groups. Moreover, in terms of factors such as life satisfaction and some domains from the Short‐form 36 Quality of Life Scale (SF‐36), subjects with minor depression presented worse self‐reported evaluations. Female gender was associated (p = 0.01) with a more frequent presence of minor depression disorder, and those with this diagnosis were more likely to have co‐morbidity with generalized anxiety disorder (p = 0.007) when compared with elderly people without any depressive disorder.

Conclusion

In this study, minor depression has been significantly associated with lower life satisfaction and worse indexes of life quality. The results supported the current concept that minor depression is prevalent in later life, especially among the oldest‐old. Subjects with minor depression had worse self‐reported opinions about memory and sleep patterns, but when these variables were objectively measured, no meaningful differences could be determined by the research team. Female gender and the concurring presence of generalized anxiety disorder were both significantly associated with the presence of minor depression diagnosis. Copyright © 2002 John Wiley & Sons, Ltd.
Validation of the Spanish version of the geriatric depression scale (GDS) in primary care
Authors: Fernández‐San Martín M. I. , Andrade C. , Molina J. , Muñoz P. E. , Carretero B. , Rodríguez M. , Silva A.
Published: October 2002

Objective

To estimate the predictive value of the 30‐question Geriatric Depression Scale (GDS) in Spanish and calculate the most adequate cut‐point for its use in Primary Health Care consultations.

Method

218 patients over the age of 64 treated at three health centers of Area 10 in Madrid were selected. In the first phase, the subjects completed the GDS, the Mini‐Mental State Examination (MMSE) and a questionnaire on health and socio‐demographic variables. They were later interviewed using the Geriatric Mental Schedule (GMS), used as the gold standard by doctors who were unaware of the results of the GDS. Two categories were contemplated according to the results of the GMS: cases of depression (diagnosis of psychotic or neurotic depression) and non‐psychiatric cases (no psychiatric diagnosis, although isolated symptoms could be present).

Results

192 aged subjects were interviewed using the GDS and the GMS. Of these, 103 were considered ‘non‐cases of depression’ and 60 others made up the ‘cases of psychotic/neurotic depression’ group. For the most effective cut‐point (9/10), sensitivity was 86.7% and specificity 63.1%. Considering a prevalence of depression of 30%, the predictive value for positives was 50.2% and for negatives 91.7%. The Cronbach alpha coefficient was 0.82, and the area below the ROC curve obtained was 0.85. Those patients with cognitive deterioration had a mean GDS score similar to those that did not present deterioration (11.16 vs 10.52; p > 0.05).

Conclusions

The Geriatric Depression Scale is valid as a screening test in Primary Care consultations due to its high sensitivity and negative predictive value. The most effective Spanish GDS cut‐point (9/10) is lower than that obtained in the original English version (10/11). Copyright © 2002 John Wiley & Sons, Ltd.
Selective non‐response to clinical assessment in the longitudinal study of aging: implications for estimating population levels of cognitive function and dementia
Authors: Anstey Kaarin J. , Luszcz Mary A.
Published: October 2002

Objective

To identify the cognitive outcome of interviewed participants who did not progress to partake in clinical assessments in a longitudinal aging study.

Design

A retrospective study was conducted on participants who were interviewed but who did not complete the clinical assessment (including an extended cognitive assessment) at either Wave 1 or both Wave 1 and Wave 3 of the Australian Longitudinal Study of Ageing. A total of 1947 participants aged 70 and older commenced the study, 246 participants without clinical data at either or both Waves 1 and 3 were identified for the sub‐sample followed‐up retrospectively. The Informant Questionnaire for Cognitive Decline in the Elderly (IQCODE) was administered to informants and medical records were reviewed.

Results

Participants who did not complete the clinical assessment at Wave 3 reported poorer health and had poorer cognitive function at Wave 1 independent of age and gender. Rates of possible dementia or cognitive decline were higher in the group who did not undertake the clinical assessment compared with both those who did the clinical assessment and with population data.

Conclusion

Selective non‐response to clinical assessment in a longitudinal aging study is associated with higher risk of cognitive decline and probable dementia. Longitudinal aging studies may underestimate rates of dementia and population levels of cognitive decline. Copyright © 2002 John Wiley & Sons, Ltd.
Spatial independent component analysis of functional MRI time‐series: To what extent do results depend on the algorithm used?
Authors: Esposito Fabrizio , Formisano Elia , Seifritz Erich , Goebel Rainer , Morrone Renato , Tedeschi Gioacchino , Di Salle Francesco
Published: October 2002

Independent component analysis (ICA) has been successfully employed to decompose functional MRI (fMRI) time‐series into sets of activation maps and associated time‐courses. Several ICA algorithms have been proposed in the neural network literature. Applied to fMRI, these algorithms might lead to different spatial or temporal readouts of brain activation. We compared the two ICA algorithms that have been used so far for spatial ICA (sICA) of fMRI time‐series: the Infomax (Bell and Sejnowski [1995]: Neural Comput 7:1004–1034) and the Fixed‐Point (Hyvärinen [1999]: Adv Neural Inf Proc Syst 10:273–279) algorithms. We evaluated the Infomax‐ and Fixed Point‐based sICA decompositions of simulated motor, and real motor and visual activation fMRI time‐series using an ensemble of measures. Log‐likelihood (McKeown et al. [1998]: Hum Brain Mapp 6:160–188) was used as a measure of how significantly the estimated independent sources fit the statistical structure of the data; receiver operating characteristics (ROC) and linear correlation analyses were used to evaluate the algorithms' accuracy of estimating the spatial layout and the temporal dynamics of simulated and real activations; cluster sizing calculations and an estimation of a residual gaussian noise term within the components were used to examine the anatomic structure of ICA components and for the assessment of noise reduction capabilities. Whereas both algorithms produced highly accurate results, the Fixed‐Point outperformed the Infomax in terms of spatial and temporal accuracy as long as inferential statistics were employed as benchmarks. Conversely, the Infomax sICA was superior in terms of global estimation of the ICA model and noise reduction capabilities. Because of its adaptive nature, the Infomax approach appears to be better suited to investigate activation phenomena that are not predictable or adequately modelled by inferential techniques. Hum. Brain Mapping 16:146–157, 2002. © 2002 Wiley‐Liss, Inc.
Neural basis of prosopagnosia: An fMRI study
Authors: Hadjikhani Nouchine , de Gelder Beatrice
Published: October 2002

Brain imaging research has identified at least two regions in human extrastriate cortex responding selectively to faces. One of these is located in the mid‐fusiform gyrus (FFA), the other in the inferior occipital gyrus (IOG). We studied activation of these areas using fMRI in three individuals with severely impaired face recognition (one pure developmental and two childhood prosopagnosics). None of the subjects showed the normal pattern of higher fMRI activity to faces than to objects in the FFA and IOG or elsewhere. Moreover, in two of the patients, faces and objects produced similar activations in the regions corresponding to where the FFA and IOG are found in normal subjects. Our study casts light on the important role of FFA and IOG in the network of areas involved in face recognition, and indicates limits of brain plasticity. Hum. Brain Mapping 16:176–182, 2002. © 2002 Wiley‐Liss, Inc.
A development framework for promoting evidence‐based policy action: drawing on experiences in Sri Lanka
Authors: Hornby P. , Perera H. S. R.
Published: October 2002

Most developing countries have embarked on one form or another of ‘health sector reform’ as a result of the global trend for health and health care reform that has emerged during the past decade. One consequence is that the issue of health sector performance is moving higher on the agenda of many developing countries, and particularly that of the corporate performance of health sector staff. Along with this movement has come increased attention to strengthening evidence‐based management decision‐making. To date, studies on measuring health sector performance, have had little impact on developing country health systems and have been limited to explorations primarily at an operational level. However, there is a growing recognition that there is a need to strengthen the policy function of ministries and their ability to monitor policy impact.

Sri Lanka is one country that has identified the need to strengthen policy at national level. Many developing countries, like Sri Lanka, are familiar with input, process and output dimensions of operational performance. However, most are not ready to engage in routine performance assessment that can strengthen policy processes at national level. This paper explores (1) the implication and the use of indicators to support evidence based policy decision‐making, and (2) the complexity of doing so in Ministries of Health that are undergoing some form of health sector reform.

The paper emphasizes that new forms of organizational support are required for performance management at policy level. A conceptual framework for managing the collection and use of performance evidence is developed, including proposals for the introduction of outcome indicators into that process. The paper concludes with recommendations on initiatives required to develop appropriate organizational and technical capacity to engage with performance management at policy level and for further research towards creating ministries of health as ‘learning organizations’ that can change and adapt with informed decisions. Copyright © 2002 John Wiley & Sons, Ltd.
A systems approach to measuring return on investment for HRD interventions
Authors: Wang Greg G. , Dou Zhengxia , Li Ning
Published: October 2002

This study contributes to the limited methodological literature on HRD program evaluation and measurement.
The study explores an interdisciplinary approach for return on investment (ROI) measurement
in human resource development (HRD) research and practices. On the basis of a comprehensive review
and analysis of relevant studies in economics, industrial‐organizational psychology, financial control,
and HRD fields, we developed a systems approach to quantitatively measure ROI for HRD programs. The ROI concept
for HRD field was defined, and a theoretical systems framework was developed. The applicability of using
statistical and mathematical operations to determine ROI and isolate non‐HRD program impacts is
discussed. Application scenarios are presented to demonstrate the utility of the systems approach in
real‐world ROI measurement for HRD interventions.
Clinical risk factors for neuroleptic malignant syndrome
Authors: Berardi Domenico , Dell'Atti Maddalena , Amore Mario , De Ronchi Diana , Ferrari Giuseppe
Published: October 2002

Pharmacological risk factors for neuroleptic malignant syndrome (NMS) are better defined than clinical risk factors. We examined the psychopathological status preceding the onset of NMS in 20 patients. We evaluated four key psychiatric symptoms (psychomotor agitation, catatonia, disorganization and confusion) and grouped them into definite clinical syndromes. Six patients presented with an acute and severe catatonic syndrome, with all the four key psychiatric symptoms. Twelve patients presented with an acute and severe disorganized psychotic episode, with two or three key psychiatric symptoms, but not catatonia. Our study suggests that a clinical syndrome of acute disorganization, in addition to acute catatonia, is a potential clinical risk factor for NMS. The two syndromes, which can occur in the context of different mental disorders, are related to each other as both implicate alteration in behavioural monitoring, and were, in our experience, unresponsive to neuroleptics. In conclusion, we hypothesize that the recognition of these two syndromes should reduce NMS occurrence. We recommend a judicious use of neuroleptics not only in patients with acute catatonia, but also in patients with acute disorganization. Copyright © 2002 John Wiley & Sons, Ltd.
Glucuronidation of olanzapine by cDNA‐expressed human UDP‐glucuronosyltransferases and human liver microsomes
Authors: Linnet Kristian
Published: October 2002

Olanzapine is a widely used, newer antipsychotic agent, which is metabolized by various pathways: hydroxylation and N‐demethylation by cytochrome P450, N‐oxidation by flavin monooxygenase and direct glucuronidation. In vivo studies have pointed towards the latter pathway as being of major importance. Accordingly, the glucuronidation reaction was studied in vitro using cDNA‐expressed human UDP‐glucuronosyltransferase (UGT) enzymes and a pooled human liver microsomal preparation (HLM). Glucuronidated olanzapine was determined by HPLC after acid or enzymatic hydrolysis. The following UGT‐isoenzymes were screened for their ability to glucuronidate olanzapine: 1A1, 1A3, 1A4, 1A6, 1A9, 2B7 and 2B15. Only UGT1A4 was able to glucuronidate olanzapine obeying saturation kinetics. The Km value was 227 μmol/l (SE 43), i.e. of the same order of magnitude as for other psychotropic drugs, and the Vmax value was 2370 pmol/(min mg) (SE 170). Glucuronidation was also mediated by the HLM preparation, but a saturation level was not reached. The olanzapine glucuronidation reaction was inhibited by several drugs known as substrates for UGT1A4, e.g. amitriptyline, trifluoperazine and lamotrigine. Thus, competition for glucuronidation by UGT1A4 represents a possibility for drug–drug interactions in subjects receiving several of these psychotropic drugs at the same time. Whether such possible interactions are of any clinical importance may await further studies in patients. Copyright © 2002 John Wiley & Sons, Ltd.
Grid‐cell‐based crop water accounting for the famine early warning system
Authors: Verdin James , Klaver Robert
Published: October 2002

Rainfall monitoring is a regular activity of food security analysts for sub‐Saharan Africa due to the potentially disastrous impact of drought. Crop water accounting schemes are used to track rainfall timing and amounts relative to phenological requirements, to infer water limitation impacts on yield. Unfortunately, many rain gauge reports are available only after significant delays, and the gauge locations leave large gaps in coverage. As an alternative, a grid‐cell‐based formulation for the water requirement satisfaction index (WRSI) was tested for maize in Southern Africa. Grids of input variables were obtained from remote sensing estimates of rainfall, meteorological models, and digital soil maps. The spatial WRSI was computed for the 1996–97 and 1997–98 growing seasons. Maize yields were estimated by regression and compared with a limited number of reports from the field for the 1996–97 season in Zimbabwe. Agreement at a useful level (r = 0·80) was observed. This is comparable to results from traditional analysis with station data. The findings demonstrate the complementary role that remote sensing, modelling, and geospatial analysis can play in an era when field data collection in sub‐Saharan Africa is suffering an unfortunate decline. Published in 2002 by John Wiley & Sons, Ltd.
A regional model of low flow for southern Taiwan
Authors: Yu Pao‐Shan , Yang Tao‐Chang , Liu Chi‐Wen
Published: October 2002

The primary purpose of this study is to develop regional models of the lower part of flow duration curves (LPFDCs) to synthesize low‐flow characteristics at ungauged sites in southern Taiwan. Because of the close relationship between low streamflow regimes and hydrogeological features, the model development first involved delimiting homogeneous hydrogeological regions by using two‐step cluster analysis. Each homogeneous region was then discriminated by an equation developed on the basis of its hydrogeological features, which was then used to determine which of three sets of regional LPFDC models would be appropriate for a particular ungauged site. Each of the three sets of regional LPFDC models were developed using both conventional multivariate statistical regression and fuzzy regression. Thirty‐four stream‐gauged watersheds located in southern Taiwan provide the data set. The study results reveal that the regional LPFDC models developed in this study could be applied reasonably at ungauged sites. Copyright © 2002 John Wiley & Sons, Ltd.
Differential production of angiostatin by concomitant antitumoral resistance‐inducing cancer cells
Authors: Binda M. Mercedes , Matar Pablo , González Alejandro D. , Rozados Viviana R. , Gervasoni Silvia I. , Scharovsky O. Graciela , Bonfil R. Daniel
Published: October 2002

The phenomenon by which tumor‐bearing hosts are capable of inhibiting secondary tumor implants or metastases, known as concomitant antitumoral resistance (CAR), is presumably due to antiangiogenesis at places distant from the primary tumor. Although angiostatin, a potent inhibitor of angiogenesis, has been reported to be one of the factors responsible for suppressing the growth of secondary tumors in mice bearing previous tumors, it has not been definitively proven yet. With the aim of investigating whether CAR‐inducing cancer cells display a differential angiostatin production and to support the role ascribed to that molecule concerning the inhibition of secondary tumor implants, 5 tumor models with different CAR‐inducing capacities were studied herein. One of the 2 human lung cancer cell lines analyzed revealed a strong CAR against secondary s.c. tumor implants in nude mice, and 2 of 3 of the murine mammary tumors used exhibited inhibitory effect on secondary s.c. and i.v. tumor inoculations in syngeneic hosts. Since angiostatin is a proteolytic fragment from plasminogen, we examined by Western blot the ability of all conditioned media collected from the tumor cells studied to convert plasminogen to angiostatin. An association between in vivo generation of CAR and in vitro conversion of plasminogen into angiostatin was found. Since different enzymatic mechanisms were described to explain the generation of angiostatin, we also studied gelatinase and urokinase‐type plasminogen activator secretion in conditioned media by zymography. The conversion of plasminogen into angiostatin by conditioned media was mainly inhibited by broad‐spectrum serine proteinase inhibitors, suggesting a possible role for 1 or more enzymes of that group in the process. These findings suggest the existence of a differential angiostatin generation by CAR‐inducing cancer cells, providing additional support to previous data obtained by other authors. © 2002 Wiley‐Liss, Inc.
Expression of MUC1 splice variants in benign and malignant ovarian tumours
Authors: Obermair Andreas , Schmid Bernd C. , Packer Leisl M. , Leodolter Sepp , Birner Peter , Ward Bruce G. , Crandon Alex J. , McGuckin Michael A. , Zeillinger Robert
Published: October 2002

MUC1 is expressed on the surface of ovarian cancer cells. Nine different splice variants of MUC1 have been described, but no study has reported on the expression of MUC1 isoforms in human ovarian cancer. Our study compares patterns of expression of MUC1 splice variants of malignant and benign ovarian tumours. Ovarian tissue samples were taken from patients with benign ovarian tumours (n = 34) and from patients who had surgery for primary (n = 47) or recurrent (n = 8) ovarian cancer. RT‐PCR for MUC1 splice variants A, B, C, D, X, Y, Z, REP and SEC was performed and their expression compared to clinical and histopathologic parameters. Variants A, D, X, Y and Z were more frequently expressed in malignant than in benign tumours. All primary ovarian cancer cases were positive for variant REP but negative for variant SEC. No significant association of the expression of MUC1 splice variants with the response to chemotherapy or patient survival could be demonstrated. Expression of MUC1 splice variants A, D, X, Y, Z and REP is associated with the presence of malignancy, whereas expression of MUC1/SEC is associated with the absence of malignancy. © 2002 Wiley‐Liss, Inc.
Clonality of multifocal urothelial carcinomas: 10 years of molecular genetic studies
Authors: Hafner Christian , Knuechel Ruth , Stoehr Robert , Hartmann Arndt
Published: October 2002

Multifocal occurrence and frequent recurrence are characteristic features of urothelial carcinomas of both the urinary bladder and the upper urinary tract. To describe the clonal nature of these tumors, 2 theories have been proposed. The monoclonality hypothesis describes the multiple tumors as descendants of a single genetically transformed cell spreading throughout the urothelium. In contrast, field cancerization caused by carcinogen exposure of the urothelium may lead to independent development of synchronous or metachronous nonrelated tumors at different sites of the urothelial tract. In the last 10 years, a multitude of molecular genetic studies have investigated the clonality of multifocal urothelial carcinomas. The majority of studies revealed a monoclonal origin of the multiple tumors. However, most of these studies investigated advanced invasive carcinomas. A small but significant proportion of multifocal urothelial carcinomas appear to arise from different clones, supporting the field‐cancerization hypothesis. Oligoclonal tumors might be more common in precursor lesions and early tumor stages. The frequent monoclonality found in patients with advanced tumors could be due to outgrowth of 1 tumor cell clone with specific genetic alterations. Two important mechanisms appear to be important for the spread of malignant cells: intraluminal seeding and intraepithelial migration. Investigation of the entire urothelial lining in patients with urothelial tumors should provide further insight into the development of multifocal urothelial carcinomas. © 2002 Wiley‐Liss, Inc.
A structural model of US aggregate job flows
Authors: Collard Fabrice , Fève Patrick , Langot François , Perraudin Corinne
Published: October 2002

This paper contributes to the analysis of jobs flows dynamics through the explicit modelling of job creations and job destructions. We propose a simple matching model extended for endogenous separation and tractable heterogeneity. The parameters of the model are estimated using a simulation‐based estimation method. We then test the ability of trade externalities, generated by the matching process, to (i) propagate reallocation and aggregate disturbances in the whole labor market and (ii) generate the observed distribution of aggregate job flows. The results clearly indicate that the model is able to match the dynamics of US aggregate job flows. Copyright © 2002 John Wiley & Sons, Ltd.
Oestrogenic activity of isobutylparaben in vitro and in vivo
Authors: Darbre P. D. , Byford J. R. , Shaw L. E. , Horton R. A. , Pope G. S. , Sauer M. J.
Published: October 2002

The alkyl esters of p‐hydroxybenzoic acid (parabens) are used widely as preservatives in foods, pharmaceuticals and cosmetics to which the human population is exposed. Recent studies have reported that methylparaben, ethylparaben, n‐propylparaben and n‐butylparaben all possess oestrogenic activity in several in vitro assays and in animal models in vivo. This study reports on the oestrogenic activity of isobutylparaben in a panel of assays in vitro and in vivo. Isobutylparaben was able to displace [3H]oestradiol from cytosolic oestrogen receptor α of MCF7 human breast cancer cells by 81% at 100 000‐fold molar excess. Using a clonal line of MCF7 cells containing a stably transfected oestrogen‐responsive ERE‐CAT reporter gene, CAT gene expression could be increased by isobutylparaben such that the magnitude of the response was the same at 10−5 M isobutylparaben as with 10−8 M 17β‐oestradiol. Isobutylparaben could also increase expression of the endogenous oestrogen‐responsive pS2 gene in MCF7 cells and maximal expression at 10−5 M isobutylparaben could be inhibited with the anti‐oestrogen ICI 182 780. The proliferation of two oestrogen‐dependent human breast cancer cell lines MCF7 and ZR‐75‐1 could be increased with isobutylparaben such that at concentrations of 10−5 M the proliferation response was of the same magnitude as with 10−8 M 17β‐oestradiol. Evidence for oestrogen receptor mediation of proliferation effects was provided by the inability of isobutylparaben to influence the growth of oestrogen‐unresponsive MDA‐MB‐231 human breast cancer cells and by the ability of the anti‐oestrogen ICI 182 780 to inhibit the isobutylparaben effects on MCF7 cell growth. The proliferation response to 10−10 M 17β‐oestradiol was not antagonized with isobutylparaben at any concentration from 10−9 M to 10−4 M in either MCF7 or ZR‐75‐1 cells. Finally, subcutaneous administration of isobutylparaben was able to increase the uterine weight in the immature mouse after three daily doses of 1.2 or 12.0 mg per mouse. Previous work using linear‐alkyl‐chain parabens has shown that oestrogenic activity increases with alkyl chain length from methylparaben to n‐butylparaben. The results here show that branching of the alkyl chain to isobutylparaben increases oestrogenic activity beyond that of the equivalent length linear alkyl chain in n‐butylparaben. Copyright © 2002 John Wiley & Sons, Ltd.
Ion leaching from dental ceramics during static in vitro corrosion testing
Authors: Milleding Percy , Haraldsson Conny , Karlsson Stig
Published: October 2002

Dental ceramics are often called inert materials. It can be hypothesized, however, that differences in the composition, microstructure, and environmental conditions will affect the degree of corrosion degradation in an aqueous environment. The aims of the study were, therefore, to study the ion dissolution from glass‐phase ceramics, with or without crystalline inclusions, and from all‐crystalline ceramics and to compare the effects of different corrosion media. Ceramic specimens were produced from glass‐phase and oxide ceramics and given an equivalent surface smoothness, after which they were subjected to in vitro corrosion (Milli‐Q water at 37 ± 2°C for 18 h and 4% acetic acid solution at 80 ± 2°C for 18 h, respectively). The temperature of the corrosion solution was slowly increased until it reached 80 ± 2°C to reduce the risk of microcrack formation at the surface. The analyses of ion leakage were performed with inductively coupled plasma optical emission spectroscopy. A large number of inorganic elements leached out from the various dental ceramics. The major leaching elements were sodium and potassium; in the acid‐corrosion experiments, there were also magnesium, silicon, and aluminum and, on a lower scale, yttrium, calcium, and chromium. The various glass‐phase ceramics displayed significant differences in ion leakage and significantly higher leakage values than all‐crystalline alumina and zirconia ceramics. No significant difference in dissolution was found between high and low‐sintering glass‐phase ceramics or between glass‐phase ceramics with high volume fractions of crystallites in the glass phase in comparison with those with lower crystalline content. It can be concluded, therefore, that none of the dental ceramics studied are chemically inert in an aqueous environment. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 541–550, 2002
Thin film rheology and lubricity of hyaluronic acid solutions at a normal physiological concentration
Authors: Tadmor Rafael , Chen Nianhuan , Israelachvili Jacob N.
Published: October 2002

Using a surface forces apparatus to measure forces, and optical (multiple beam) interferometry to measure surface shapes and separations (to ±1 Å), the normal, viscous, and shear (lubrication) forces between smooth mica surfaces in aqueous hyaluronic acid (HA) solutions were measured. The experimental conditions of loading pressures, pH, and HA concentration were set to closely correspond to physiological human knee‐joint conditions. From the force and optical (refractive index) measurements, it was concluded that, like other negatively charged polyelectrolytes, HA does not naturally adsorb on the mica surface which is hydrophilic and weakly negatively charged at physiological conditions: the polymer solution exhibits the bulk viscosity (22.5 ± 1.5 cP) for films thicker than about 0.4 μm of the polymer, whereas for thinner films, the viscosity decreases monotonically toward the value of the pure electrolyte solution (1 cP) as HA is extruded from between the surfaces. This is indicative of a repulsive “depletion” interaction of HA with each mica surface and to a weakly attractive polymer‐mediated force between the two surfaces. Thus, free HA in synovial fluid is not expected to act as a good “boundary lubricant.” Relaxation measurements on approaching and receding surfaces in HA solutions were also performed, and it is shown that the presence of HA in the bulk solution can improve “hydrodynamic” modes of lubrication, for example, by assuaging the compression stroke. The study includes information that is beneficial to researchers working with biomaterials viscosupplementation devices. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 514–523, 2002
Polymer–calcium phosphate cement composites for bone substitutes
Authors: Mickiewicz Rafal A. , Mayes Anne M. , Knaack David
Published: October 2002

The use of self‐setting calcium phosphate cements (CPCs) as bioresorbable bone‐replacement implant materials presently is limited to non‐load‐bearing applications because of their low compressive strength relative to natural bone. The present study investigated the possibility of strengthening a commercially available CPC, α‐BSM™, by incorporating various water‐soluble polymers into the cement paste during setting. Several polyelectrolytes, poly(ethylene oxide), and the protein bovine serum albumin (BSA) were added in solution to the cement paste to create calcium phosphate–polymer composites. Composites formulated with the polycations poly(ethylenimine) and poly(allylamine hydrochloride) exhibited compressive strengths up to six times greater than that of pure α‐BSM™ material, with a maximum value reached at intermediate polymer content and for the highest molecular weight studied. Composites containing BSA developed compressive strengths twice that of the original cement at protein concentrations of 13–25% by weight. In each case, XRD studies correlate the improvement in compressive strength with reduced crystallite dimensions, as evidenced by a broadening of the (0,0,2) reflection. This suggests that polycation or BSA adsorption inhibits crystal growth and possibly leads to a larger crystal aspect ratio. SEM results indicate a denser, more interdigitated microstructure. The increased strength was attributed to the polymer's capacity to bridge between multiple crystallites (thus forming a more cohesive composite) and to absorb energy through plastic flow. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 581–592, 2002
Repair of segmental defects in rabbit humeri with titanium fiber mesh cylinders containing recombinant human bone morphogenetic protein‐2 (rhBMP‐2) and a synthetic polymer
Authors: Murakami Narumichi , Saito Naoto , Horiuchi Hiroshi , Okada Takao , Nozaki Kazutoshi , Takaoka Kunio
Published: October 2002

To develop a new technology that enhances the regeneration potential of bone and the repair of large intercalated defects in long bone, recombinant human bone morphogenetic protein‐2 (BMP‐2; 20 μg or 40 μg) was mixed in a polymer gel (poly‐lactic acid‐polyethyleneglycol block copolymer; PLA‐PEG; 200 mg) and incorporated into titanium fiber‐mesh cylinders. Three 5‐mm cylinders were placed end‐to‐end to fill a 15‐mm defect created in the humeri of adult rabbits and were stabilized by an intramedullary rod. In controls, the titanium fiber‐mesh cylinders were combined with PLA‐PEG in the absence of BMP. Six weeks after implantation, new bone had formed on the surface of the implant and had bridged the defect. All of the defects (5/5) treated by cylinders containing 120 μg (40 μg × 3) of BMP were repaired completely. New bone formation was also found inside the pores of the cylinders. The defect was not repaired in the control animals. These results demonstrate that these new composite implants fabricated by combining rhBMP, synthetic degradable polymers and compatible biomaterials enhance the regeneration potential of bone. Thus, it is possible that large skeletal defects can be repaired using this prosthesis in lieu of autogenous bone graft. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 169–174, 2002
In vitro change in mechanical strength of β‐tricalcium phosphate/copolymerized poly‐L‐lactide composites and their application for guided bone regeneration
Authors: Kikuchi Masanori , Koyama Yoshihisa , Takakuda Kazuo , Miyairi Hiroo , Shirahama Noriaki , Tanaka Junzo
Published: October 2002

Novel composites of bioactive β‐tricalcium phosphate [Ca3(PO4)2] and biodegradable copolymerized poly‐L‐lactide (CPLA) were prepared by a heat‐kneading method. The mechanical and chemical changes of the composites were evaluated in vitro by soaking in physiological saline and Dulbecco's phosphate buffered saline. When soaked in physiological saline, the 3‐point mechanical strength decreased rapidly from 60 to 30 MPa in the initial 4 weeks and then gradually reached a plateau; the initial decrease in the mechanical strength was ascribed to the dissolution of β‐tricalcium phosphate from the surface. The mechanical properties evident at 8–12 weeks were sufficient for the composites to be used as a biodegradable material for regeneration of bone because the hydrolysis of CPLA was inhibited in both physiological saline and phosphate‐buffered saline as a result of a pH‐buffering effect. Composite membranes 250‐μm thick were used to regenerate large bone defects in beagle dogs: 10 × 10 × 10 mm3 in volume in the mandible and 20 mm in length in the tibia. The afflicted areas covered with the composite membranes were almost perfectly filled with new bone 12 weeks after the operation, whereas those covered with a CPLA membrane or without any membranes were invaded by soft tissue. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 265–272, 2002
Kinetic study of citric acid influence on calcium phosphate bone cements as water‐reducing agent
Authors: Sarda S. , Fernández E. , Nilsson M. , Balcells M. , Planell J. A.
Published: October 2002

Most of the research performed on calcium phosphate bone cements (CPBCs) has dealt with the improvement of bone cement formulations for new, demanding bone‐filling applications. In particular, the development of injectable bone cements is of real interest for the biomedical community. The aim of this work was to study the effect of citric acid on the injectability and the setting properties of alpha‐tricalcium phosphate‐based cements. A comparative kinetic study was performed on cements with and without citric acid relating the hardening curves and the hydration rates using a mathematical approach. Citric acid behaved as a fluidificant during the first stages of the cement mixing. The dissolution‐precipitation reactions of the alpha‐tricalcium phosphate were retarded with the addition of citric acid and the compressive strength at saturation increased. In conclusion, citric acid can behave as a water‐reducing admixture. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 653–659, 2002
Tissue response to microfibers of different polymers: Polyester, polyethylene, polylactic acid, and polyurethane
Authors: Sanders J. E. , Bale S. D. , Neumann T.
Published: October 2002

Tissue response to single polymer microfibers of polyester (PET), polyethylene (PE), poly(L‐lactic acid) (PLA), and polyurethane (PU) was assessed using a rat subcutaneous model. Fibers of diameters ranging from 1 to 15 μm were aligned parallel to each other on polycarbonate frames and implanted in the subcutaneous dorsum in the subscapular region. After 5 weeks of implantation, fibrous capsule thickness was significantly less for fibers of diameters 1–5 than for those of 11–15 μm for all polymers tested. For PET and PU, 75.0 and 71.4% respectively of the 1–5 μm fibers had no capsule, while for PE and PLA only 45.5 and 56.3% respectively had no capsule. For 1–5 μm fibers, PE had significantly thicker capsules than PET and PU. Reducing fiber diameters from 6–10 to 1–5 μm induced a greater reduction in capsule thickness than changing polymers among PET, PE, and PLA. PU showed the least encapsulation of all polymers, demonstrating significantly thinner capsules than PET, PE, and PLA for 6–10 and 11–15 μm fibers. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 222–227, 2002
Enhancement of osteogenesis on hydroxyapatite surface coated with synthetic peptide (EEEEEEEPRGDT) in vitro
Authors: Itoh D. , Yoneda S. , Kuroda S. , Kondo H. , Umezawa A. , Ohya K. , Ohyama T. , Kasugai S.
Published: October 2002

Some dental implants are coated with hydroxyapatite (HA), which preferentially binds to bone. Several matrix proteins have an arginine‐glycine‐aspartic acid (RGD) sequence where cells attach via an integrin receptor. We hypothesized that coating an HA surface with an RGD‐containing peptide might enhance the attachment and differentiation of osteoblasts. The HA disks (diameter 34 mm, thickness 1 mm) were treated with a solution (50 mM Tris/HCl and 150 mM NaCl, pH 7.4) containing the peptide EEEEEEEPRGDT, in which the E repetition exerts a high affinity to HA. After washing with phosphate‐buffered saline, KUSA/A1 mouse osteoblastic cells were inoculated onto the HA surface and cultured. After 30 min, the number of cells attached to the surface was counted. The DNA content and alkaline phosphatase (ALP) activity were measured after 10 days in culture. Expression of bone matrix proteins was also examined by means of reverse transcriptase–polymerase chain reaction at 7 days; the mineralized area of the culture was also evaluated by staining with Alizarin Red S after 10 days. Treatment with the peptide stimulated cell attachment and increased DNA content and ALP activity. Furthermore, matrix protein expression and mineralized nodule formation were enhanced to a greater extent on the peptide‐treated surface than on the nontreated surface. Our results indicate that coating an HA surface with RGD‐containing peptide enhances osteoblast attachment and differentiation. This peptide treatment of HA‐coated implants may stimulate the osseointegration of the implants. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 292–298, 2002
Comparison between modifications of lens proteins resulted from glycation with methylglyoxal, glyoxal, ascorbic acid, and fructose
Authors: Argirova Mariana , Breipohl Winrich
Published: October 2002

Cataract is generally associated with the breakdown of the lens microarchitecture. Age‐dependent chemical modifications and cross‐linking of proteins are the major pathways for development of lens opacity. The specific alterations in lens proteins caused by glycation with four carbonyl metabolites, fructose, methylglyoxal, glyoxal, and ascorbic acid, were investigated. Decrease in intensity of tryptophan related fluorescence and level of reduced protein sulfhydryl groups, parameters that are indicative for changes in protein conformation, were observed after reaction with all studied carbonyl compounds. Protein carbonyl content, an index for oxidative damage to proteins, was strongly enhanced in methylglyoxal‐treated proteins. Cross‐linking of glycated proteins was confirmed by polyacrylamide electrophoresis. α‐Oxoaldehydes were the most reactive in protein aggregation. They also formed specific chromophores absorbing UV light above 300 nm. Significant loss in lactate dehydrogenase activity resulted from incubation with methylglyoxal, followed by glyoxal and ascorbic acid. The results obtained showed that alterations in lens proteins do not follow the specific reactivity of studied carbonyl compounds. Despite the similarity in chemical structures of α‐oxoaldehydes and ascorbic acid degradation products, they cause specific alterations in lens protein structure with different biological consequences. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:140–145, 2002. DOI 10.1002/jbt.10031