bluuebunny/crossref_metadata_2025 huggingface dataset:
β‐Adrenergic blockade in the dentate gyrus in vivo prevents high frequency‐induced long‐term potentiation of EPSP slope, but not long‐term potentiation of population spike amplitude
Authors: Munro Catherine A.M. , Walling Susan G. , Evans John H. , Harley Carolyn W.
Published: August 2002

High frequency (HF)‐induced and norepinephrine (NE)‐induced long‐term potentiation have been hypothesized to utilize common mechanisms of induction and expression in the dentate gyrus. In vitro data tend to support this hypothesis, but few studies have been done in vivo. The present study records perforant path‐evoked potentials simultaneously on two micropipettes, one filled with saline and the other with the β‐antagonist, timolol. Stimulation of the paragigantocellularis nucleus (PGi) was used as a method of producing NE release in the dentate gyrus, and thus, to assess the efficacy of β‐receptor blockade on the timolol pipette. β‐blockade by timolol attenuated PGi‐induced spike potentiation. HF‐induced potentiation of the excitatory post‐synaptic potential (EPSP) slope was also blocked by timolol, but HF‐induced spike amplitude potentiation was unaffected. These results are consistent with an earlier report examining HF‐long‐term potentiation (LTP) following 6‐OHDA‐induced NE depletion, which showed that the EPSP slope LTP depended, for its full expression, on NE, but potentiation of the population spike amplitude component of HF‐induced LTP did not. In the present study, PGi‐induced potentiation of spike amplitude on the saline pipette was normal after HF‐induced saturation of spike amplitude potentiation, suggesting that the mechanisms for expression of spike potentiation, as well as induction of spike potentiation, are separate for HF and NE stimulation. Hippocampus 2001;11:322–328. © 2001 Wiley‐Liss, Inc.
Improvement of the basic correlating equations and transition criteria of natural convection heat transfer
Authors: Yang Shi‐Ming
Published: August 2002

In this paper, improvements in the basic physical laws of natural convection heat transfer were implemented in two major respects by incorporating recent research findings in this field. A preferred transition criterion was adopted in this paper to correlate all of the experimental data. Since transition correlations are primarily flow stability problems, the Grashof number, instead of the Rayleigh number, was found to be the preferred criterion. Furthermore, in the case of natural convection heat transfer from a horizontal cylinder, a series of experimental data in the high‐Rayleigh‐number regions recently became available. These data made it possible to establish new reliable correlations and also to test the validity of previous correlations. It is concluded that the previous correlation for a horizontal cylinder in high‐Rayleigh‐number regions was based on unreliable experimental results. The transition correlation for a horizontal cylinder occurred at much higher values of Rayleigh number than the previous recommendation. In the case of natural convection heat transfer from a vertical plate, more accurate property values for air under pressurized conditions are now available. This made it possible to replot the reliable data of Saunders. From this result and the experimental result of Warner and Arpaci, a new set of basic correlations in natural convection heat transfer for laminar, transitional, and turbulent regimes are recommended. These recommendations reflect a better understanding of the basic physical laws in the field of heat convection. © 2001 Scripta Technica, Heat Trans Asian Res, 30(4): 293–300, 2001
Subjective ratings of prospective memory deficits in MDMA (‘ecstasy’) users
Authors: Heffernan Thomas M. , Ling Jonathon , Scholey Andrew B.
Published: August 2002

Chronic use of MDMA (3,4‐methylenedioxymethamphetamine), or ‘ecstasy’, is associated with significant cognitive impairments, particularly in laboratory and field tests of memory for previously encoded material. Less is known about the effects of a history of MDMA use on aspects of everyday cognitive functioning–of which prospective memory (typically characterised as ‘remembering to do something at some future point’) is an important aspect. Self‐ratings of prospective memory among 30 regular ecstasy users (taking the drug 10 or more times per month) and 31 ecstasy‐free controls were compared. Each participant completed the Prospective Memory Questionnaire, which measures self‐rated error frequencies relating to three aspects of prospective memory (short‐term habitual, long‐term episodic and internally cued); the scale also records the use of strategies to aid remembering. Compared with non‐users, ecstasy users reported significantly more self‐rated errors in prospective memory, an effect which was evident after co‐varying levels of other drug use. There were no significant differences in the use of strategies to aid memory. These findings provide new insights into prospective memory dysfunction in recreational drug users. Prospective memory deficits may be related to the reported serotonergic and frontal lobe deficits in chronic MDMA users. It is necessary to use more objective tasks to assess putative prospective memory deficits in ecstasy users. Copyright © 2001 John Wiley & Sons, Ltd.
Evaluating explicit and implicit routing for watershed hydro‐ecological models of forest hydrology at the small catchment scale
Authors: Tague C. L. , Band L. E.
Published: August 2002

This paper explores the behaviour and sensitivity of a watershed model used for simulating lateral soil water redistribution and runoff production. In applications such as modelling the effects of land‐use change in small headwater catchments, interactions between soil moisture, runoff and ecological processes are important. Because climate, soil and canopy characteristics are spatially variable, both the pattern of soil moisture and the associated outflow must be represented in modelling these processes. This study compares implicit and explicit routing approaches to modelling the evolution of soil moisture pattern and spatially variable runoff production. It also addresses the implications of using different landscape partitioning strategies. This study presents the results of calibration and application of these different routing and landscape partitioning approaches on a 60 ha forested watershed in Western Oregon. For comparison, the different approaches are incorporated into a physically based hydro‐ecological model, RHESSys, and the resulting simulated soil moisture, runoff production and sensitivity to unbiased error are examined. Results illustrate that both routing approaches can be calibrated to achieve a reasonable fit between observed and modelled outflow. Calibrated values for effective watershed hydraulic conductivity are higher for the explicit routing approach, which illustrates differences between the two routing approaches in their representation of internal watershed dynamics. The explicit approach illustrates a seasonal shift in drainage organization from watershed to more local control as climate goes from a winter wet to a summer dry period. Assumptions used in the implicit approach maintain the same pattern of drainage organization throughout the season. The implicit approach is also more sensitive to random error in soil and topographic input information, particularly during wetter periods. Comparison between the two routing approaches illustrates the advantage of the explicit routing approach, although the loss of computational efficiency associated with the explicit routing approach is noted. To compare different strategies for partitioning the landscape, the use of a non‐grid‐based method of partitioning is introduced and shown to be comparable to grid‐based partitioning in terms of simulated soil moisture and runoff production. Copyright © 2001 John Wiley & Sons, Ltd.
On the information content of forest transpiration measurements for identifying canopy conductance model parameters
Authors: Dekker S. C. , Bouten W. , Bosveld F. C.
Published: August 2002

Generally, forest transpiration models contain model parameters that cannot be measured independently and therefore are tuned to fit the model results to measurements. Only unique parameter estimates with high accuracy can be used for extrapolation in time or space. However, parameter identification problems may occur as a result of the properties of the data set. Time‐series of environmental conditions, which control the forest transpiration, may contain periods with redundant or coupled information, so called collinearity, and other combinations of conditions may be measured only with difficulty or incompletely. The aim of this study is to select environmental conditions that yield a unique parameter set of a canopy conductance model. The parameter identification method based on localization of information (PIMLI) was used to calculate the information content of every individual artificial transpiration measurement. It is concluded that every measurement has its own information with respect to a parameter. Independent criteria were assessed to localize the environmental conditions, which contain measurements with most information. These measurements were used in separate subdata sets to identify the parameters. The selected measurements do not overlap and the accuracies of the parameter estimates are maximized. Measurements that were not selected do not contain additional information that can be used to further maximize the parameter accuracy. Thereupon, the independent criteria were used to select eddy correlation measurements and parameters were identified with only the selected measurements. It is concluded that, for this forest and data set, PIMLI identifies a unique parameter set with high accuracy, whereas conventional calibrations on subdata sets give non‐unique parameter estimates. Copyright © 2001 John Wiley & Sons, Ltd.
A simple model of river meandering and its comparison to natural channels
Authors: Lancaster Stephen T. , Bras Rafael L.
Published: August 2002

We develop a new method for analysis of meandering channels based on planform sinuosity. This analysis objectively identifies three channel‐reach lengths based on sinuosity measured at those lengths: the length of typical, simple bends; the length of long, often compound bends; and the length of several bends in sequence that often evolve from compound bends to form multibend loops. These lengths, when normalized by channel width, tend to fall into distinct and clustered ranges for different natural channels. Mean sinuosity at these lengths also falls into distinct ranges. That range is largest for the third and greatest length, indicating that, for some streams, multibend loops are important for planform sinuosity, whereas for other streams, multibend loops are less important. The role of multibend loops is seldom addressed in the literature, and they are not well predicted by previous modelling efforts. Also neglected by previous modelling efforts is bank–flow interaction and its role in meander evolution. We introduce a simple river meandering model based on topographic steering that has more in common with cellular approaches to channel braiding and landscape evolution modelling than to rigorous, physics‐based analyses of river meandering. The model is sufficient to produce reasonable meandering channel evolution and predicts compound bend and multibend loop formation similar to that observed in nature, in both mechanism and importance for planform sinuosity. In the model, the tendency to form compound bends is sensitive to the relative magnitudes of two lengths governing meander evolution: (i) the distance between the bend cross‐over and the zone of maximum bank shear stress, and (ii) the bank shear stress dissipation length related to bank roughness. In our simple model, the two lengths are independent. This sensitivity implies that the tendency for natural channels to form compound bends may be greater when the banks are smoother. Copyright © 2002 John Wiley & Sons, Ltd.
The hydrology of the upper Swan River Estuary with focus on an artificial destratification trial
Authors: Hamilton David P. , Chan Terence , Robb Malcolm S. , Pattiaratchi Chari B. , Herzfeld Michael
Published: August 2002

A trial to artificially destratify part of the water column of the Swan–Canning Estuary took place over four weeks in 1997. Destratification was attempted with bubble plumes created by pumping compressed air through a porous pipe near the bed at a location in the upper estuary. The purpose of the trial was to determine whether the resultant bubble ‘curtain’ could mix the water column, thereby altering the extent of upstream and downstream mixing and the vertical structures of salinity, temperature, dissolved oxygen and turbidity. The destratification trial was monitored using three techniques: vertical profiles taken on several days at selected stations along the estuary, fine scale profiles in the vicinity of the bubble curtain on one day, and continuous water column profiles taken 1 km upstream of the curtain. The seasonal upstream propagation of brackish water underneath a residual freshwater discharge was affected by the magnitude of freshwater discharge and tidal elevations. Superimposed upon diurnal and semi‐diurnal tides were non‐tidal water level changes induced mostly by variations in barometric pressure. These caused large changes in the salt wedge position. Destratification by the bubble curtain was compromised by these large oscillations, which limited the exposure of the salt wedge region to the mixing action of the bubble curtain. Complete vertical mixing of the water column was observed up to 30 m either side of the curtain on 30 October. Disruptions to the density stratification were not evident beyond 350 m of the curtain. In the immediate vicinity (∼30 m) of the curtain, deficits of dissolved oxygen in bottom waters were generally reduced or obliterated and a naturally turbid plume of water near the bottom of the estuary was mixed through the water column. The effects of the bubble curtain on dissolved oxygen, turbidity and temperature were, however, similar to those for salinity, with mixing confined to around 30 m from the curtain and no effect observed further than 350 m away. The upper Swan River estuary, although relatively narrow and strongly vertically stratified, is unsuited to destratification using bubble plumes. Cycling of spring and neap tides and non‐tidal water level changes, together with freshwater inflows to the estuary, strongly limit the longitudinal extent of mixing by bubble curtains. Copyright © 2001 John Wiley & Sons, Ltd.
Observational data and scale‐dependent parameterizations: explorations using a virtual hydrological reality
Authors: Bashford Kathy E. , Beven Keith J. , Young Peter C.
Published: August 2002

The use of small‐scale process descriptions at larger scales has been identified as a major problem in hydrological modelling. An alternative is to use measurements taken at a larger scale, such as remote sensing data, and to develop process descriptions at that scale.

A hypothetical catchment area, or ‘virtual hydrological reality’ dataset has been generated to explore the value of different types of data in model structure and parameter identification. Though only an approximation to the natural responses of the catchment, this virtual reality can be used to explore the use of observational series that would not normally be available.

A data‐based mechanistic approach was used to model evapotranspiration from 1 km data, as though they were available from remote sensing. The resulting parameterization is of a similar form to an evaporative fraction model. It is an example of the type of parameterization that could be used to describe the land surface, without estimation of effective parameters from small‐scale measurements, and avoiding overparameterization. Copyright © 2002 John Wiley & Sons, Ltd.
Peculiarities of ice events in Russian Arctic rivers
Authors: Vuglinsky V. S.
Published: August 2002

The state‐of‐the‐art of the hydrological network for the study of river‐ice regimes in the Russian Arctic is reviewed as well as the regularly published documents that characterize specific features of ice events. The dates of the beginning of different ice events (e.g. ice drift, ice‐cover formation, frazil ice drift, etc.) are analysed as well as the duration of such events for 16 rivers typical of the Russian Arctic. It is demonstrated that ice on Arctic rivers of Asian Russia forms earlier and breaks up later compared to those of European Russia; this is explained by the more severe climate conditions that affect the northern areas of Siberia. Ice‐cover duration on the study rivers varies from 140 to 250 days with the maximum duration being observed in the lower reaches of large rivers in East Siberia and the Far East. Ice‐cover duration and the latitude of the observation stations are strongly correlated. The dynamics of ice‐cover growth and melting on rivers, ice thickness and snow‐pack depth on the ice are considered in different parts of the Russian Arctic. It is demonstrated that the nature of ice growth during the autumn–winter period and its decrease in spring mainly depend on the thermal conditions during a particular year. In years with low air temperatures, ice‐cover thickness in the rivers of the Far East can attain 200 cm and greater, meanwhile it may be 50 or 60 cm only in the rivers of European Russia if the winter is warm. Particular case studies are given to illustrate these features. Copyright © 2002 John Wiley & Sons, Ltd.
The effects of log erosion barriers on post‐fire hydrologic response and sediment yield in small forested watersheds, southern California
Authors: Wohlgemuth Peter M. , Hubbert Ken R. , Robichaud Peter R.
Published: August 2002

Wildfire usually promotes flooding and accelerated erosion in upland watersheds. In the summer of 1999, a high‐severity wildfire burned a series of mixed pine/oak headwater catchments in the San Jacinto Mountains of southern California. Log erosion barriers (LEBs) were constructed across much of the burned area as an erosion control measure. We built debris basins in two watersheds, each about 1 ha in area, one with LEBs, the other without, to measure post‐fire hydrologic response and sediment yield and to evaluate the effectiveness of the LEBs. The watersheds are underlain by granitic bedrock, producing a loamy sand soil above large extents of weathered bedrock and exposed core stones (tors) on the surface. Measured soil water‐repellency was similar over the two catchments. Rain gauges measured 348 mm of precipitation in the first post‐fire year. The ephemeral stream channels experienced surface flow after major rainstorms, and the source of the water was throughflow exfiltration at the slope/channel interface. Post‐fire overland flow produced some rilling, but hillslope erosion measured in silt fences away from any LEBs was minor, as was sediment accumulation behind the LEBs. Stream channels in the catchments exhibited minor net scour. Water yield was much greater in the LEB‐treated watershed. This resulted in 14 times more sediment yield by weight than the untreated watershed. Average soil depths determined by augering were nearly double in the catchment without the LEBs compared with the treated watershed. This suggests that differences in water and sediment yield between the two catchments are due to the twofold difference in the estimated soil water‐holding capacity in the untreated watershed. It appears that the deeper soils in the untreated watershed were able to retain most of the precipitation, releasing less water to the channels and thereby reducing erosion and sediment yield. Thus, the test of LEB effectiveness was inconclusive in this study, because soil depth and soil water‐holding capacity may have masked their performance. Published in 2001 John Wiley & Sons, Ltd.
Farnesyl thiosalicylic acid inhibits the growth of melanoma cells through a combination of cytostatic and pro‐apoptotic effects
Authors: Smalley Keiran S.M. , Eisen Tim G.
Published: August 2002

Novel classes of drug that interfere with the signalling of the small G‐protein Ras, the so‐called Ras antagonists, are showing much promise as novel anti‐cancer agents. In this study, we demonstrate that the novel Ras antagonist farnesylthiosalicylic acid (FTS) inhibits the growth of Colo 853 melanoma cells through a combination of cytostatic and pro‐apoptotic effects. Furthermore, these phenomena are seen under conditions of cell attachment and in the presence of serum. Treatment of Colo 853 cells with FTS led to time‐dependent inhibition of constitutive Akt, retinoblastoma protein (pRB) and ERK activity, with a concurrent loss of Akt expression. Inhibition of Akt and ERK activity induces apoptosis in other human cancer cell lines. Here it is demonstrated that inhibition of Akt, or ERK and Akt in combination, leads to cell cycle arrest but not apoptosis in melanoma cells. FTS treatment was also found to upregulate activity of the stress‐activated p38 MAP kinase. Inhibition of p38 MAP kinase, using the selective inhibitor SB 203580, followed by FTS treatment, significantly increased the proportion of apoptotic cells after 72 hr, possibly suggesting a modulatory role for p38 MAP kinase in FTS‐induced melanoma cell apoptosis. © 2002 Wiley‐Liss, Inc.
Breast cancer risk factors and age at diagnosis: An Icelandic cohort study
Authors: Tryggvadóttir Laufey , Tulinius Hrafn , Eyfjord Jórunn E. , Sigurvinsson Trausti
Published: August 2002

An increasing number of studies indicates that the strength and even direction of association between breast cancer and established risk factors differ according to the woman's age when she develops the disease. This was studied in the setting of a population based cancer registry using a databank with information on age at menarche, parity, age at first birth, oral contraceptive (OC) use, lactation, height and weight. From a cohort of 80.219 women attending population‐based cervical and breast cancer screening in Iceland, 1120 cases were identified, aged 26–90 years at diagnosis and 10,537 controls, individually matched to the cases on birth year and age when attending. Information given at last visit before diagnosis was used in the analysis, applying conditional logistic regression. Odds ratios and statistical strength of relationships varied according to age at diagnosis for age at first birth, number of births, duration of lactation, height and weight. The decreased risk associated with young age at first birth and increasing duration of breast feeding became less pronounced with advancing age at diagnosis. A reduced risk associated with an increasing number of births was not detected in women diagnosed under the age of 40. An increased risk associated with giving first birth after 30 years of age was mainly detected in women who had only given 1 birth and were diagnosed under the age of 40 (OR = 7.06 95% CI = 2.16–23.01). A positive association with height and especially with weight was confined to women diagnosed after the age of 55. The results confirm that age at diagnosis should be taken into account when studying the effects of breast cancer risk factors. © 2002 Wiley‐Liss, Inc.
Clinical impact and functional aspects of tenascin‐C expression during glioma progression
Authors: Herold‐Mende Christel , Mueller Margareta M. , Bonsanto Mario M. , Schmitt Horst Peter , Kunze Stefan , Steiner Hans‐Herbert
Published: August 2002

The extracellular matrix protein tenascin‐C is expressed in processes like embryogenesis and wound healing and in neoplasia. Tenascin‐C expression in gliomas has been described previously; however, the relation to clinical data remains inconsistent. Generally, analysis of tenascin‐C function is difficult due to different alternatively spliced isoforms. Our studies focus on changes in tenascin‐C expression in human gliomas, correlating these changes with tumor progression and elucidating the functional role of the glioma cell‐specific tenascin‐C isoform pool. Eighty‐six glioma tissues of different World Health Organization (WHO) grades were analyzed immunohistochemically for tenascin‐C expression. The influence of the specific tenascin‐C isoforms produced by glioblastoma cells on proliferation and migration was examined in vitro using blocking antibodies recognizing all isoforms. In general, tenascin‐C expression increased with tumor malignancy. Perivascular staining of tenascin‐C around tumor‐supplying blood vessels was observed in all glioblastoma tissues, whereas in WHO II and III gliomas, perivascular tenascin‐C staining appeared less frequently. The appearance of perivascular tenascin‐C correlated significantly with a shorter disease‐free time. Analysis of proliferation and migration in the presence of blocking antibodies revealed an inhibition of proliferation by around 30% in all 3 glioblastoma cell cultures, as well as a decrease in migration of 30.6–46.7%. Thus we conclude that the endogenous pool of tenascin‐C isoforms in gliomas supports both tumor cell proliferation and tumor cell migration. In addition, our data on the perivascular staining of tenascin‐C in WHO II and III gliomas and its correlation with a shorter disease‐free time suggest that tenascin‐C may be a new and potent prognostic marker for an earlier tumor recurrence. © 2002 Wiley‐Liss, Inc.
Cytotoxic T lymphocyte mediated recognition of human pancreatic cancer cells
Authors: Peiper Matthias , Sato Takeo , Streichert Thomas , Eisenberger Claus Ferdinand , Knoefel Wolfram Trudo , Izbicki Jakob Robert
Published: August 2002

T lymphocytes play an important role in tumor rejection and their response to human malignant melanoma has been well documented. In contrast, the existence of cytotoxic T lymphocytes (CTL) to pancreatic cancer remains unclear. Tumor‐associated lymphocytes (TAL) and peripheral blood monocytes (PBMC) were isolated from pancreatic cancer patients. Tumor‐specific CTL were generated from TAL and PBMC using solid‐phase anti‐CD3, low‐dose IL‐2 (50 IU/ml) and repetitive autologous tumor stimulation. The specificity of CTL was tested in standard cytotoxicity assays using autologous tumor cells, autologous fibroblasts when available, several allogeneic pancreatic tumor cells and the NK‐sensitive cell line K562. Anti‐HLA‐Class I MAb, W6/32, was used to demonstrate that tumor‐specific CTL were HLA‐Class I restricted. HLA‐molecules of human pancreatic cancer cells were washed out using acid elution. Eight consecutive, histologically confirmed pancreatic cancer specimen as well as peripheral blood mononuclear cells were analyzed. CTL were capable of lysing autologous tumor cells significantly after 3 stimulations with autologous tumor cells. T cell mediated recognition was HLA‐Class I restricted as shown by incubation with MAb anti‐HLA‐Class I. In case of HLA‐A2 positivity, incubation of tumor cells in cytotoxicity assays resulted in significant inhibition. Autologous fibroblasts or K562 cells were lysed significantly less. HLA‐Class I molecule elution resulted in significantly lower recognition of these cells by CTL. These results show for the first time in a larger series the possibility of generating CTL in human pancreatic cancer. The identification of new tumor associated antigens or tumor antigens will be crucial for establishing new treatment strategies. © 2002 Wiley‐Liss, Inc.
Inhibition of experimental pulmonary metastasis by controlling biodistribution of catalase in mice
Authors: Nishikawa Makiya , Tamada Ayumi , Kumai Hitomi , Yamashita Fumiyoshi , Hashida Mitsuru
Published: August 2002

In a previous study, we showed that targeted delivery of bovine liver catalase to hepatocytes by direct galactosylation augmented the inhibitory effect of the enzyme on experimental hepatic metastasis of colon carcinoma cells (unpublished data). Here, we examined the ability of catalase to inhibit tumor metastasis to the lung by controlling its biodistribution. Four types of catalase derivative, Gal‐CAT, Man‐CAT, Suc‐CAT and PEG‐CAT, were synthesized. Experimental pulmonary metastasis was induced in mice by i.v. injection of 1 × 105 colon 26 tumor cells. An i.v. injection of catalase (35,000 units/kg) partially, but significantly, decreased the number of colonies in the lung 2 weeks after tumor injection, from 93 ± 29 (saline injection) to 63 ± 23 (p < 0.01). Suc‐CAT, Man‐CAT and Gal‐CAT showed effects similar to those of catalase on the number of colonies. However, PEG‐CAT greatly inhibited pulmonary metastasis to 22 ± 11 (p < 0.001). Furthermore, s.c. injection of catalase also greatly inhibited metastasis (11 ± 6, p < 0.001). Neither inactivated catalase nor BSA showed any effects on the number of metastatic colonies, indicating that the enzymatic activity of catalase to detoxify H2O2 is the critical factor inhibiting metastasis. 111In‐PEG‐CAT showed a sustained concentration in plasma, whereas s.c.‐injected 111In‐catalase was slowly absorbed from the injection site. These results suggest that retention of catalase activity in the circulation is a promising approach to inhibit pulmonary metastasis. © 2002 Wiley‐Liss, Inc.
Expression of heavy subunit of γ‐glutamylcysteine synthetase (γ‐GCSh) in human colorectal carcinoma
Authors: Tatebe Shigeru , Unate Hitoshi , Sinicrope Frank A. , Sakatani Takashi , Sugamura Kenji , Makino Masato , Ito Hisao , Savaraj Niramol , Kaibara Nobuaki , Kuo M. Tien
Published: August 2002

Gamma‐glutamylcysteine synthetase (γ‐GCS) is a heterodimer consisting of heavy (γ‐GCSh) and light (γ‐GCSl) subunits. γ‐GCS catalyzes the rate‐limiting de novo biosynthesis of glutathione (GSH), an abundant physiological antioxidant that plays important roles for regulating oxidative stress. Expression of γ‐GCSh and γ‐GCSl are sensitive to oxidative stress. To investigate whether expression of γ‐GCS is correlated with tumor progression, we used immunohistochemical approaches to examine 16 human colorectal adenomas and resected 57 carcinomas from untreated patients. In adjacent normal colorectal epithelium, levels of γ‐GCSh expression were low. Strong cytoplasmic staining for γ‐GCSh was detected in 3 (18.8%) adenoma and 48 (84.2%) carcinomas. The frequency of γ‐GCSh expression in carcinoma was significantly higher than in adenoma (p<0.0001). We used RNase protation assay and Western blot to determine levels of γ‐GCSh mRNA and protein from 10 pairs of matched carcinomas with adjacent normal controls. Elevated expression of both γ‐GCSh mRNA and protein were found in 6 cases, suggesting that transcriptional and/or posttranscriptional regulation play an important role in the upregulation of γ‐GCS during colorectal carcinogenesis. We also examined the expression of another redox‐regulated gene, multidrug resistance protein 1 (MRP1). Strong staining for MRP1 was detected in 1 (6.3%) adenoma and 40 (70.2%) carcinomas. The frequency of MRP1 expression in carcinoma was significantly higher than in adenoma ( p<0.0001). Nuclear p53 expression was detected in 30 (52.6%) of carcinomas. There is a significant correlation between γ‐GCSh and MRP1 expression (p=0.013) but not between γ‐GCSh and p53. Since γ‐GCS is a sensor of oxidative stress, these results are consistent with the notion that oxidative stress is associated with colorectal tumor progression. © 2002 Wiley‐Liss, Inc.
A comparative study of normal inspection, autofluorescence and 5‐ALA‐induced PPIX fluorescence for oral cancer diagnosis
Authors: Betz Christian S. , Stepp Herbert , Janda Philip , Arbogast Susanne , Grevers Gerhard , Baumgartner Reinhold , Leunig Andreas
Published: August 2002

Fluorescence diagnosis aims to improve the management of oral cancer via early detection of the malignant lesions and better delimitation of the tumor margins. This paper presents a comparative study of normal inspection, combined fluorescence diagnosis (CFD) and its 2 main components, autofluorescence and 5‐aminolevulinic acid (5‐ALA)‐induced protoporphyrin IX (PPIX) fluorescence. Biopsy‐controlled fluorescence imaging and spectral analysis were performed on a total of 85 patients with suspected or histologically proven oral carcinoma both before and after topical administration of 5‐ALA (200 mg 5‐ALA dissolved in 50 ml of H20). Fluorescence excitation was accomplished using filtered light of a xenon short arc lamp (λ = 375–440 nm). As for CFD, a “streetlight” contrast (red to green) was readily found between malignant and healthy tissue on the acquired images. In terms of tumor localization and delimitation properties, CFD was clearly favorable over either normal inspection or its 2 components in fluorescence imaging. The performance of CFD was found to be impeded by tumor keratinization but to be independent of either tumor staging, grading or localization. In spectral analysis, cancerous tissue showed significantly higher PPIX fluorescence intensities and lower autofluorescence intensities than normal mucosa. There is a great potential for CFD in early detection of oral neoplasms and exact delimitation of the tumors' superficial margins and an advantage over white light inspection and each of its 2 main components. The method is noninvasive, safe and easily reproducible. © 2002 Wiley‐Liss, Inc.
Long‐term memory in stock market returns: international evidence
Authors: Sadique Shibley , Silvapulle Param
Published: August 2002

A lot of recent work has addressed the issue of the presence of long memory components in stock prices because of the controversial implications of such a finding for market efficiency and for martingale models of asset prices used in financial economics and technical trading rules used for forecasting. This paper examines the presence of long memory in the stock returns of seven countries, namely Japan, Korea, New Zealand, Malaysia, Singapore, the USA and Australia. The classical and modified rescaled range tests, the semiparametric test proposed by Geweke and Porter‐Hudak, the frequency domain score test proposed by Robinson and its time‐domain counterpart derived by Silvapulle, are applied to these returns in order to detect the long memory property. Evidence suggests that the Korean, Malaysian, Singapore and New Zealand stock returns are long‐term dependent, indicating that these two markets are not efficient. The results of this study should be useful to regulators, practitioners and derivative market participants, whose success precariously depends on the ability to forecast stock price movements. Copyright © 2001 John Wiley & Sons, Ltd.
Irreducibility and structural cointegrating relations: an application to the G‐7 long‐term interest rates
Authors: Barassi Marco R. , Caporale Guglielmo Maria , Hall Stephen G.
Published: August 2002

In this paper we examine the causal linkages between the G‐7 long‐term interest rates by using a new technique, which enables the researcher to analyse relations between a set of I(1) series without imposing any identification conditions based on economic theory. Specifically, we apply the so‐called Extended Davidson's Methodology (EDM), which is based on the innovative concept of an irreducible cointegrating (IC) vector, defined as a subset of a cointegrating relation that does not have any cointegrated subsets. Ranking the irreducible vectors according to the criterion of minimum variance allows us to distinguish between structural and solved relations. The empirical results provide support for the hypothesis that larger, more stable economies can achieve policy objectives more successfully by accommodating rather than driving other countries' policies. It appears that the driving force is Canada, which is linked to the USA, UK and France in three out of the four fundamental relations, and which is a reference point for the US, Italian and German rates, which are not cointegrated, seem to be determined by country‐specific factors. Copyright © 2001 John Wiley & Sons, Ltd.
Retire to where? A discrete choice model of residential location
Authors: Duncombe William , Robbins Mark , Wolf Douglas A.
Published: August 2002

Many studies of migration attempt to identify attributes of places that influence residential location decisions. Most such studies relate an area's migration rates to its own attributes, or the flow of migrants between two areas to the attributes of both places. We focus on retirement migration within the US, and extend the literature by using a discrete choice framework in which a person's location decision depends on the attributes of all potential locations. Using a multinomial logit specification and 1990 Census county‐to‐county migration data, we model the location choice of individuals aged 65 to 74 years from among more than 3000 counties. In order to make the estimation problem manageable, we employ the sampling‐of‐alternatives approach of McFadden, and use aggregated migratory‐flow data for which existing estimation software is applicable. Our results indicate that, in general, persons around retirement age avoid high taxes and housing costs, while they are drawn to areas with relatively high spending on such services as fire, police and recreation. Amenities such as coastline and warm weather are also valued. Copyright © 2001 John Wiley & Sons, Ltd.
Alterations in hepatic detoxifying enzymes induced by new organophosphorus insecticides following subchronic exposure in rats
Authors: Mahboob M. , Siddiqui M. K. J.
Published: August 2002

The present study examined the structure–toxicity relationship of two novel phosphorothionates, a methyl ester (RPR‐II) and an ethyl ester (RPR‐V), with regard to their interaction with certain biochemical indices in rat. Male rats were treated orally with 10% (low), 20% (medium) and 30% (high) doses of the two compounds (14, 28 and 42 µg kg−1 day −1 of RPR‐II and 33, 66 and 99 µg kg−1 day−1 of RPR‐V) daily for 90 days. The activity of hepatic glutathione S‐transferase (GST) and UDP‐glucuronyl transferase (UDPGT) and the level of glutathione (GSH) were estimated at 0, 45 and 90 days of treatment as well as 28 days after cessation of treatment. RPR‐II caused statistically significant depletion of GSH after 45 and 90 days of treatment at the high dose, whereas RPR‐V depleted GSH only after 90 days at the high dose. RPR‐II inhibited GST after 45 and 90 days at medium and high doses, whereas RPR‐V caused inhibition of GST after 45 and 90 days only at the high dose. Significantly, UDPGT activity was increased only by the high dose of RPR‐II after 90 days. However, a dose and time‐dependent increase in UDPGT activity was observed at all three doses of RPR‐V after 45 and 90 days. There was no modulation in any of the three indices at low doses of the two organophosphorus insecticides. The withdrawal study revealed that induced changes in hepatic parameters were reversible 28 days after cessation of treatment. The results indicated that the two insecticides had different potential to modulate hepatic GST, UDPGT and GSH due to subchronic exposure and that these metabolic alterations are quite reversible after withdrawal of treatment. Copyright © 2001 John Wiley & Sons, Ltd.
Micro‐wear patterns on UHMWPE tibial inserts in total knee joint simulation
Authors: Tamura Jiro , Clarke Ian C. , Kawanabe Keiichi , Akagi Masao , Good Victoria D. , Williams Paul A. , Masaoka Toshinori , Schroeder Dave , Oonishi Hironobu
Published: August 2002

The objective of this study was to examine both simulator and retrieved total knee replacement polyethylene inserts to confirm, using scanning electron microscopy, whether similar micro‐wear patterns to those seen on retrieved inserts were reproduced on simulator specimens. The simulator specimens consisted of samples subjected to sliding and rolling movement (Experiment 1) and to sliding movement only (Experiment 2). Samples from Experiment 1 demonstrated longitudinal patterns in the middle of the wear track and transverse patterns in the anterior and posterior ends, whereas in Experiment 2, only transverse patterns were observed. In the retrieved specimens, both longitudinal and transverse patterns were observed. The results showed that the simulator study reproduced similar patterns of micro‐damage on polyethylene, and that the longitudinal micro‐wear pattern was related to the rolling movement that is distinctive in knee kinematics. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 218–225, 2002
The effect of structural characteristics on the in vitro bioactivity of hydroxyapatite
Authors: Shi Donglu , Jiang Gengwei , Bauer Jennifer
Published: August 2002

In previous studies a film of hydroxylapatite (HA) was coated onto the inner pore surfaces of reticulated alumina for bone substitutes with the use of a so‐called thermal deposition method. In this process, the HA films must be sintered at high temperatures for a strong adhesion to the alumina substrate. It has been found that high‐temperature sintering inevitably changes the crystallinity of the coated HA, and in turn affects its bioactivity. Therefore, in this study, in vitro experiments were carried out to investigate the effects of structural changes on the in vitro bioactivity. The factors dominating in vitro bioactivity of HA, including surface area, degree of crystallinity, and temperature, were identified. The activation energy for volume diffusion was calculated for different in vitro solution temperatures. Also discussed is the underlying mechanism of growth and dissolution processes during the in vitro test. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 71–78, 2002
The sintered microsphere matrix for bone tissue engineering: In vitro osteoconductivity studies
Authors: Borden Mark , Attawia Mohamed , Laurencin Cato T.
Published: August 2002

A tissue engineering approach has been used to design three‐dimensional synthetic matrices for bone repair. The osteoconductivity and degradation profile of a novel polymeric bone‐graft substitute was evaluated in an in vitro setting. Using the copolymer poly(lactide‐co‐glycolide) [PLAGA], a sintering technique based on microsphere technology was used to fabricate three‐dimensional porous scaffolds for bone regeneration. Osteoblasts and fibroblasts were seeded onto a 50:50 PLAGA scaffold. Morphologic evaluation through scanning electron microscopy demonstrated that both cell types attached and spread over the scaffold. Cells migrated through the matrix using cytoplasmic extensions to bridge the structure. Cross‐sectional images indicated that cellular proliferation had penetrated into the matrix approximately 700 μm from the surface. Examination of the surfaces of cell/matrix constructs demonstrated that cellular proliferation had encompassed the pores of the matrix by 14 days of cell culture. With the aim of optimizing polymer composition and polymer molecular weight, a degradation study was conducted utilizing the matrix. The results demonstrate that degradation of the sintered matrix is dependent on molecular weight, copolymer ratio, and pore volume. From this data, it was determined that 75:25 PLAGA with an initial molecular weight of 100,000 has an optimal degradation profile. These studies show that the sintered microsphere matrix has an osteoconductive structure capable of functioning as a cellular scaffold with a degradation profile suitable for bone regeneration. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 421–429, 2002
Biological characterization of a novel biodegradable antimicrobial polymer synthesized with fluoroquinolones
Authors: Woo G. L. Y. , Yang M. L. , Yin H. Q. , Jaffer F. , Mittelman M. W. , Santerre J. P.
Published: August 2002

Biomaterial‐related infections continue to represent a significant challenge to the medical community. Several approaches have been utilized to incorporate antimicrobial agents at the surface of implant devices in attempts to delay or eliminate the formation of biofilms. To date, most of these strategies have focused on drug conjugation or diffusion‐limited systems for the delivery of such pharmaceutical agents. More recently, work has been presented on the feasibility of incorporating drugs into the backbone of polymers as a main‐chain monomer. When sequenced into the backbone of the polymer with other monomers that are hydrolytically sensitive to enzyme‐catalyzed breakdown, it is thought that drugs may be able to be selectively released. Specifically, degradable polyurethanes have been synthesized with fluoroquinolone antibiotics and have shown an ability to kill bacteria when released following degradation of the polymer chains by the macrophage‐derived enzyme cholesterol esterase. However, specificity of the cleavage sites in the polymer was difficult to control. Since cholesterol esterase has specificity for hydrophobic moieties, it is desirable to alter the formulation of the polyurethanes to incorporate long hydrophobic monomers immediately adjacent to the ciprofloxacin molecule. Hence, the current study focuses on evaluating the enzyme‐catalyzed degradation of a degradable polyurethane synthesized with 1,12 diisocyanatododecane as a substitute for 1,6 diisocyanatohexane, which was used in previous work. Validation of specific ciprofloxacin release and the generation of antimicrobial are shown. A preliminary cell study to assess the cytotoxicity of this biodegradable antibiotic polymer shows that the material has no observable effects on cell proliferation or cell membrane structure. © 2001 Wiley Periodicals, Inc., J Biomed Mater Res 59: 35–45, 2002
Hypothermia‐induced platelet aggregation in human blood in an in vitro model: The dominant role of blood‐material interactions
Authors: Hall Matthew W. , Solen Kenneth A.
Published: August 2002

Hypothermia‐induced platelet aggregation (HIPA) with or without neutrophil involvement may cause neurologic dysfunction during hypothermic surgery. We report the use of a previously developed model to study the contributions of several surfaces, surface area, shear rate, and blood–material exposure time to HIPA. Heparinized (1.5 u/mL) human blood was quenched to 24°C and passed (0.5 mL/min) through a 75‐cm long 1/32” ID tubing of polyvinylchloride (PVC), polyethylene (PE), polyurethane (PU), Teflon‐FEP, or heparin (Duraflo)‐coated PVC. The number of aggregates was measured by a light‐scattering method, and the concentration of occlusive aggregates was assessed using constant‐pressure filtration (50 mmHg). No differences were seen among PVC, PE, PU, or Teflon‐FEP. The heparin‐coated PVC tubing produced fewer occlusive aggregates, and heparin leaching from the coating was not the cause of the decrease in occlusive aggregates. Increasing surface area increased the number of aggregates, and increasing shear rates decreased the occlusiveness of those aggregates. ©2001 Wiley Periodicals, Inc. J Biomed Mater Res 59: 528–534, 2002
Biocompatibility of fluorinated polyimide
Authors: Kanno M. , Kawakami H. , Nagaoka S. , Kubota S.
Published: August 2002

Contact between blood and biomaterial triggers a complex series of events including protein adsorption, leukocyte adhesion and activation, and complement activation. In this article, a series of fluorinated polyimides cured at a different temperatures was prepared, and the biocompatibility of the membranes was evaluated using in vitro protein adsorption, neutrophil adhesion, and complement activation experiments under static conditions. We found that protein adsorption, neutrophil adhesion, and complement activation for the polyimides significantly depends on the curing temperature and decreases with an increase in the temperature and that the polyimide has a good biocompatibility compared with poly(styrene) and polydimethylsiloxane. We concluded that the rearrangement of molecules such as CF3, sulfone, and ketone at the outermost surface occurs because of curing, which induces an increase in the hydrophobicity and that the cured polyimide suppresses protein adsorption, neutrophil adhesion, and complement activation because of its high hydrophobicity and low surface free energy. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res, 60, 53–60, 2002.