bluuebunny/crossref_metadata_2025 huggingface dataset:
RGD‐containing peptides inhibit intestinal regeneration in the sea cucumber Holothuria glaberrima
Authors: Cabrera‐Serrano Arelys , García‐Arrarás José E.
Published: June 2004

The sea cucumber Holothuria glaberrima is an echinoderm capable of regenerating its viscera. Previous studies from our group have shown a striking remodeling of the extracellular matrix (ECM) during intestinal regeneration. To study the role of the ECM during regeneration, we have focused on the RGD sequences present in many ECM molecules. Regenerating animals were treated with an RGDS (Arg‐Gly‐Asp‐Ser) peptide that competes with the interaction between RGD sequence and cellular integrins. Saline and RGES (Arg‐Gly‐Glu‐Ser) peptide injections were done as controls. The size of the regenerating intestine was determined, and the regenerating structures were analyzed by immunohistochemistry for the presence of collagen and fibronectin, as well as for muscle and other cells. The results show a delay in intestinal regeneration in animals injected with the RGDS peptide, suggesting that the ECM–integrin interaction plays an important function in the regenerative process. Developmental Dynamics 231:171–178, 2004. © 2004 Wiley‐Liss, Inc.
Recapitulation of the parathyroid hormone‐related peptide–Indian hedgehog pathway in the regenerating deer antler
Authors: Faucheux C. , Nicholls B.M. , Allen S. , Danks J.A. , Horton M.A. , Price J.S.
Published: June 2004

Parathyroid hormone (PTH)‐related peptide (PTHrP) and the PTH/PTHrP receptor (PPR) play an essential role in controlling growth plate development. The aim of the present study was to use the deer antler as a model to determine whether PTHrP and PPR may also have a function in regulating cartilage and bone regeneration in an adult mammal. Antlers are the only mammalian appendages that are able to undergo repeated cycles of regeneration, and their growth from a blastema involves a modified endochondral process. Immunohistochemistry was used to establish sites of localization of PTHrP and PPR in antlers at different stages of development. The pattern of Indian Hedgehog (IHH) and transforming growth factor‐beta1 (TGFβ1) distribution was also investigated, because PTHrP expression in the developing limb is regulated by IHH and during embryonic growth plate formation TGFβ1 acts upstream of PTHrP to regulate the rate of chondrocyte differentiation. In the antler blastema (<10 days of development), PTHrP, PPR, and TGFβ1 were localized in epidermis, dermis, regenerating epithelium, and in mesenchymal cells but IHH expression was not detected. In the rapidly growing antler (weeks 4–8 of development), PTHrP, PPR, and TGF β1 were localized in skin, perichondrium, undifferentiated mesenchyme, recently differentiated chondrocytes, and in perivascular cells in cartilage but not in fully differentiated hyperytrophic chondrocytes. IHH was restricted to recently differentiated chondrocytes and to perivascular cells in cartilage. In mineralized cartilage and bone, PTHrP, PPR, IHH, and TGFβ1 were immunolocalized in perivascular cells and differentiated osteoblasts. PTHrP and PPR were also present in the periosteum. TGFβ1 in vitro stimulated PTHrP synthesis by cells from blastema, perichondrium, and cartilage. The findings of this study suggest that molecules which regulate embryonic skeletal development and postnatal epiphyseal growth may also control blastema formation, chondrogenesis, and bone formation in the regenerating deer antler. This finding is further evidence that developmental signaling pathways are recapitulated during adult mammalian bone regeneration. Developmental Dynamics 231:88–97, 2004. © 2004 Wiley‐Liss, Inc.
Modulation of activin/bone morphogenetic protein signaling by follistatin is required for the morphogenesis of mouse molar teeth
Authors: Wang Xiu‐Ping , Suomalainen Marika , Jorgez Carolina J. , Matzuk Martin M. , Wankell Miriam , Werner Sabine , Thesleff Irma
Published: June 2004

Teeth form as ectodermal appendages, and their morphogenesis is regulated by conserved signaling pathways. The shape of the tooth crown results from growth and folding of inner dental epithelium, and the cusp patterning is regulated by transient signaling centers, the enamel knots. Several signal proteins in the transforming growth factor‐β (TGFβ) superfamily are required for tooth development. Follistatin is an extracellular inhibitor of TGFβ signaling. To investigate the roles of follistatin during tooth development, we analyzed in detail the expression patterns of follistatin, activin βA, as well asBmp2,Bmp4, andBmp7during tooth morphogenesis. We also examined the tooth phenotypes of follistatin knockout mice and of transgenic mice overexpressing follistatin in the epithelium under the keratin 14 (K14) promoter. The folding of the dental epithelium was aberrant in the molars of follistatin knockout mice, and the cusps were shallow with reduced cell proliferation and lack of anteroposterior polarization. The functions of both primary and secondary enamel knots were apparently disturbed. In K14–follistatin transgenic mice, the molar cusp pattern was also seriously affected (although different from the follistatin knockouts) and the occlusal surfaces of the molars were whorled. Their enamel was prematurely worn. In addition, all of the third molars were missing. Our results indicate that follistatin regulates morphogenesis and shaping of the tooth crown. We propose that finely tuned antagonistic effects between follistatin and TGFβ superfamily signals are critical for enamel knot formation and function, as well as for patterning of tooth cusps. Developmental Dynamics 231:98–108, 2004. © 2004 Wiley‐Liss, Inc.
A cohort‐based approach for characterizing lifetime inhalation cancer risk from time‐varying exposure to air toxics from ambient sources
Authors: Cook Richard , Jones Baxter L. , Cleland Joshua
Published: June 2004

In recent years, the U.S. EPA as well as state and local agencies have released a number of risk characterizations addressing potential inhalation cancer risks from exposure to ambient sources of air toxics (e.g., U.S. EPA's 1993 Motor Vehicle‐Related Air Toxics Study, the South Coast Air Quality Management District's MATES‐II study, the U.S. EPA's National Scale Air Toxics Assessment). In these assessments, quantitative estimates of cancer risk are often presented as point estimates and/or distributions of individual upper‐bound lifetime risks. The individual upper‐bound lifetime cancer risk is the probability that an individual in a given population will contract cancer if exposed continuously to a given concentration of an airborne carcinogen over an assumed lifetime. Individual risk estimates in these studies are usually based on average or median exposures for a wide population distribution.

These estimates generally assume continuous exposure over an entire lifetime to levels estimated for 1 or a few years and do not account for expected changes in exposure over time. For example, risk estimates in U.S. EPA's recent National Scale Air Toxics Assessment assume individuals will be exposed to 1996 levels over a 70‐year lifetime. However, exposures to most air toxics are expected to change over time as a result of mobile and stationary source emission control programs.

In this paper, a cohort‐based approach, which estimates individual lifetime cancer risk based on time‐weighted exposure over a lifetime, is presented. This approach accounts for changes in exposure level over time, including decreases anticipated as a result of regulatory programs. It also incorporates differences in exposures to children and adults that result from certain differences in time–activity patterns, integrating them into a single value for a cohort. Moreover, this paper presents a case study applying this approach to estimate average nationwide individual cancer risks from exposure to the highway mobile source contribution to ambient benzene. The case study includes estimates for the general population and a highly exposed demographic group, outdoor workers. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 120–125, 2004
Case study of a potency‐weighted emission screen
Authors: Daugherty Douglas D. , Dehuff Kimberly (Mertz) , Caviness Gwen
Published: June 2004

According to the U.S. Environmental Protection Agency (USEPA) document entitled Risk Assessment Guidance for Superfund (RAGS) (EPA/540/1–89/002, U.S. Environmental Protection Agency, Office of Emergency and Remedial Response, Washington, DC, 1989), a concentration‐toxicity screen is one of the chemicals of potential concern (COPCs) selection processes that may be employed to reduce the number of chemicals carried through a human health risk assessment. COPCs are those constituents for which carcinogenic risks and noncarcinogenic hazards are estimated. This paper describes the results of an analogous approach to rank chemicals at a facility according to their emission rates and potency. The objective of our proposed COPC selection methodology was to consider the comprehensive list of chemicals used in normal operations at a facility with a large chemical inventory and to identify those chemicals that have the potential to contribute at least 90 to 95% of the estimated risk for the facility (i.e., the main risk drivers). By focusing our efforts on this shorter list of chemicals, we increased the accuracy of information obtained from facility personnel and improved the level of confidence in the emission estimation, air dispersion modeling, and risk assessment results. While this approach does not consider constituent transport from multiple facility sources or proximity of receptors to those sources, these effects were evaluated in the subsequent air dispersion modeling and risk assessment of facility emissions. An evaluation of the subsequent risk assessment analyses demonstrated that the potency‐weighted emissions screen was successful in determining the list of chemicals responsible for 90 to 95% of the estimated carcinogenic risks and noncarcinogenic hazards. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 168–177, 2004
Methods for incorporating uncertainty into dispersion and deposition models
Authors: Williamson Derek G. , Graettinger Andrew J. , Yegnan Anand
Published: June 2004

Dispersion and deposition models are critical components of risk assessments for airborne discharge from industrial facilities. The probabilistic nature of risk assessment, the complexities of dispersion and deposition models, and the natural variability of input parameters all support the need for probabilistic output from dispersion/deposition models. However, difficulty in implementation and data availability has prevented the routine use of uncertainty in dispersion/deposition modeling. A series of relatively simple case studies demonstrate that the Taylor series is a flexible and computationally efficient method for incorporating input uncertainty into a widely used air transport model (ISCST). Relatively simple dispersion and dispersion with deposition modeling scenarios using real input data demonstrate that the Taylor series: (1) provides similar estimates of uncertainty compared to traditional Monte Carlo simulation, (2) is far more computationally efficient, and (3) in most cases provides conservative estimates of output concentration. More over, an evaluation the computational time needed for traditional Monte Carlo simulation when considering several input variables simultaneously demonstrates the potential of the Taylor series technique to estimate uncertainty in far more complicated modeling scenarios. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 158–167, 2004
Community preparedness and response model for addressing environmental risk and vulnerability
Authors: Uddin Nasim , Peters Robert W. , Haque Akhlaque
Published: June 2004

This paper investigates a community preparedness and response model for addressing environmental risk and vulnerability that will significantly lessen loss of human life and lower the cost of disaster recovery in a region. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 126–134, 2004
Assessing ozone networks using positive matrix factorization
Authors: Rizzo Michael J. , Scheff Peter A.
Published: June 2004

In 2001, the United States Environmental Protection Agency (USEPA) began the process of examining the national monitoring networks to assess the contribution of individual monitoring sites in providing useful information to the public and regulatory agencies. One of the first networks to be examined was ozone, with the assessment being initially completed on a national level and then further refined on a regional basis. The goal of the regional analysis was to determine which monitors may be providing redundant information and could, therefore, be removed or relocated to another area in need of additional monitoring data.

One technique which was used in the regional analysis of the ozone network was positive matrix factorization (PMF). This technique is similar to classical factor analysis, which allows for a series of related variables to be grouped into a smaller set of independent factors that represent combinations of the original variables. In addition to grouping the data into factors, this novel approach also provides predicted values of the analysis variable. Comparison of the predicted to the actual values not only gave an indication of how well the model fitted the ozone concentrations, but also aided in the determination of the information value of individual monitors.

Hourly ozone data were polled from the USEPA's national data archive for a total of 24 states for the prime ozone formation months of May through September for 1996 to 2000. Daily maximum 8‐hour concentrations were calculated for each site according to the methods contained in 40 CFR Part 50 Appendix H. Because PMF requires a complete data record across all sites for all days analyzed, sites that were missing data were interpolated linearly over time.

The results of the PMF analysis contained 10 factors representing various areas of the country including the Lake Michigan, Atlantic Coast, North Carolina, St. Louis/Indianapolis, Upper New York State, Ohio, Pennsylvania, Kansas/Southeast Missouri/Arkansas, Minnesota/Northwest Wisconsin, and Kentucky/Tennessee areas. Actual to predicted ratios were calculated for each day at each site and the coefficients of variation (CVs) of the individual ratio distributions were utilized as a metric to determine which sites were consistently being predicted well by PMF. Sites with low CVs were interpreted as being well predicted and considered not to be providing ambient ozone information as valuable as that provided by monitors that were poorly predicted by the model. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 110–119, 2004
Planning for the future—Development of action criteria that balance regulatory risks versus market and production requirements at an opthalmic lens coating facility
Authors: Hangal Sunil P. , Hober Michael J. , Sweeney Paul
Published: June 2004

A growing ophthalmic coating facility based in Florida must plan for the future by balancing the risks associated with environmental regulatory requirements and production requirements based on market and business conditions. The lens coating operations at this facility utilize both volatile organic compounds and hazardous air pollutants. The type and quantity of coatings utilized relative to market demands for products in the future may potentially result in the facility exceeding major source thresholds under Title V of the Clean Air Act, thus requiring permit changes and, most likely, emissions controls. A description of the facility, as well as the environmental risks is presented relative to potential “responses” available for consideration under present production variations. An in‐depth analysis of the various options for compliance and control management as well as operational flexibility in order to meet business demands is provided. The evaluation includes options in becoming a major facility under Clean Air Act Title V requirements, application of Maximum Available Control Technology requirements, and options in managing chemical inventory and production techniques to avoid major source thresholds, if it is possible to do so. This analysis will establish the framework by which company management can implement a formal program with automatic response activities that are put into effect when facility emissions exceed preestablished thresholds. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 135–140, 2004
Efficient sampling techniques for uncertainties in risk analysis
Authors: Wang Renyou , Diwekar Urmila , Grégoire Padró Catherine E.
Published: June 2004

Risk and policy analysis involves consideration of uncertainties. A quantitative probabilistic method for uncertainty analysis includes: (1) quantifying and assigning probabilistic distributions to the input uncertainties, (2) sampling the distributions of these uncertain parameters in an iterative fashion using Monte Carlo methods, (3) propagating the effects of uncertainties through the model, and (4) predicting the outcomes in terms of probabilistic measures like mean, variance, and fractiles. However, the results of the probabilistic analysis depend on the number of samples chosen. The sample size required for a particular analysis depends on various factors such as type of model, the random number generator used, type of distributions, and the output probabilistic measure and cannot be universally defined. The general tendency is to reduce the samples as much as possible without realizing the effect on decisions. For example, the mean of the output requires a number of samples that is an order of magnitude less compared to the variance. Therefore, it is desirable to use a sampling technique that can predict the output probabilistic measure accurately with the minimum number of samples. In this work, we present new sampling techniques based on Quasi‐Monte Carlo sequences and Latin hypercube sampling. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 141–157, 2004
Editors' notes
Authors: Thompson‐Robinson Melva , Hopson Rodney , SenGupta Saumitra
Published: June 2004

Editors' notes
A focus on cultural variables in evaluating an Upward Bound Program
Authors: Zulli Rebecca A. , Frierson Henry T.
Published: June 2004

This chapter highlights the evaluative process and selected findings from an evaluation of an Upward Bound program. The chapter examines and documents factors and strategies that contributed to the high degree of success experienced in the program.
Walking pathways toward becoming a culturally competent evaluator: Boundaries, borderlands, and border crossings
Authors: Symonette Hazel
Published: June 2004

This chapter shares insights derived from one practitioner's continuing journey toward excellence in mainstreaming culturally responsive evaluation processes, practices, and products. Evaluation's intrinsic value as a self‐diagnostic resource for critical and creative reflection, empowered self‐improvement, and strategic image management is spotlighted.
A finite volume unstructured multigrid method for efficient computation of unsteady incompressible viscous flows
Authors: Tai Chin Hoe , Zhao Yong
Published: June 2004

An unstructured non‐nested multigrid method is presented for efficient simulation of unsteady incompressible Navier–Stokes flows. The Navier–Stokes solver is based on the artificial compressibility approach and a higher‐order characteristics‐based finite‐volume scheme on unstructured grids. Unsteady flow is calculated with an implicit dual time stepping scheme. For efficient computation of unsteady viscous flows over complex geometries, an unstructured multigrid method is developed to speed up the convergence rate of the dual time stepping calculation. The multigrid method is used to simulate the steady and unsteady incompressible viscous flows over a circular cylinder for validation and performance evaluation purposes. It is found that the multigrid method with three levels of grids results in a 75% reduction in CPU time for the steady flow calculation and 55% reduction for the unsteady flow calculation, compared with its single grid counterparts. The results obtained are compared with numerical solutions obtained by other researchers as well as experimental measurements wherever available and good agreements are obtained. Copyright © 2004 John Wiley & Sons, Ltd.
Arginine deiminase enhances dexamethasone‐induced cytotoxicity in human T‐lymphoblastic leukemia CCRF‐CEM cells
Authors: Noh Eun‐Joo , Kang Sang‐Wook , Shin Yong‐Jae , Choi Sang‐Hyun , Kim Chan‐Gil , Park In‐Sun , Wheatley Denys N. , Min Bon‐Hong
Published: June 2004

Since arginine deiminase (ADI; EC 3.5.3.6) inhibits cell proliferation by arresting cells in the G1phase, we tested its synergistic effect on cell death induced by dexamethasone (DEX), which also induces apoptosis by G1cell cycle arrest. ADI inhibited cell proliferation and induced apoptosis in human leukemic CEM cells in a dose‐dependent manner. Simultaneous treatment with ADI and DEX showed synergistic effects on DNA fragmentation and LDH release. In addition, ADI exerted its anti‐proliferative activity against DEX‐resistant CEM cells. ADI suppressed expression of c‐myc, a potential key regulator of cell proliferation and apoptosis, and increased expression of p27Kip1cyclin‐dependent kinase inhibitor. These results suggest that ADI efficiently increases the anti‐cancer effect of DEX on human leukemic CEM cells through G1cell cycle arrest involving downregulation of c‐myc and upregulation of p27Kip1. © 2004 Wiley‐Liss, Inc.
PTEN promoter is methylated in a proportion of invasive breast cancers
Authors: Khan Salma , Kumagai Takashi , Vora Jaimini , Bose Namrata , Sehgal Indu , Koeffler Phillip H. , Bose Shikha
Published: June 2004

The PTEN protein is a negative regulator of the Akt pathway, leading to suppression of apoptosis and increased cell survival. Its role as a tumor‐suppressor gene has been adequately substantiated, and homozygous mutations have been demonstrated in familial and sporadic cancers. In breast cancers, expression of PTEN protein is lost/reduced in 38% of cases. Somatic mutations are, however, rarely found. Our study was therefore designed to determine if differential methylation of the PTEN promoter region has a role in the transcriptional inactivation of the gene in invasive breast carcinomas. A total of 44 samples of invasive human breast cancer, 5 breast cancer cell lines and 16 samples of normal human breast tissue from young and elderly women were studied for methylation of the PTEN promoter by methylation‐specific PCR and PTEN protein expression by immunohistochemistry. PTEN methylation occurred in 34% of breast cancers, and 60% of these samples were associated with loss of PTEN protein. Analyzed from a different perspective, 34% of breast cancers had reduced expression of PTEN and 60% had a methylated PTEN promoter. None of the breast cancer cell lines and normal breast tissues showed methylation. In summary, methylation of the PTEN promoter leads to PTEN inactivation in a subset of human breast cancers. © 2004 Wiley‐Liss, Inc.
An investigation of mammographic density and gene variants in healthy women
Authors: Maskarinec Gertraud , Lurie Galina , Williams Andrew E. , Le Marchand Loic
Published: June 2004

This cross‐sectional study examined if polymorphisms in genes that code for enzymes involved in the production and metabolism of estrogens are associated with mammographic density, a strong predictor of breast cancer risk. The study included 328 healthy women of different ethnicities who underwent mammographic screening and donated a blood or mouthwash sample for DNA analysis. After digitizing cranio‐caudal views of the mammograms, we performed computer‐assisted mammographic density assessment. Following DNA extraction, samples were analyzed for polymorphisms in theCOMT(Val158Met),CYP1A1(Ile462Val),CYP1B1(Val432Leu),CYP1A2(*1F) andCYP17(T27C) genes using PCR‐RFLP. Breast density was lower in Caucasians than in Asians. Caucasian women were less likely to carry theCYP1A1variant allele and more likely to carry the variant alleles forCYP1B1andCOMTthan women with Asian or Hawaiian ancestry. The low‐activityCOMTandCYP1A2variant alleles were weakly related to lower percent mammographic density after adjustment for age, ethnicity, body mass index and reproductive variables (pfor gene‐dosage effect = 0.08 and 0.05, respectively). These relations were observed in premenopausal women only and were similar in direction and magnitude after stratification by ethnicity. We found no significant associations between breast density and the variant alleles forCYP1A1, CYP1B1andCYP17.Our data suggest lower mammographic density for women carrying theCOMTandCYP1A2variant alleles than for women carrying the common alleles, though this is the opposite of what is commonly hypothesized from the enzyme function. © 2004 Wiley‐Liss, Inc.
Bioassessment of Selected Inland Water Bodies in Sri Lanka Using Benthic Oligochaetes with Consideration of Temporal Variations
Authors: Pathiratne Asoka , Weerasundara Ajith
Published: June 2004

The organic pollution status of three inland water bodies in Sri Lanka was evaluated using benthic oligochaete communities with the environmental characteristics considering temporal variation over one year period. Oligochaete species richness and abundance was consistently higher in the highly eutrophic and organically polluted Lake Beira in comparison with the less polluted water bodies. In a cluster analysis of oligochaete community compositions, the assemblages grouped by the water bodies rather than by months. Principal component analysis revealed that the structure of the oligochate community was mainly influenced by conductivity, nitrate, biochemical oxygen demand levels of water and organic carbon content of the sediment. In the ordination, the polluted Lake Beira separated from the other water bodies along the first axis. The results revealed that there could be a potential for using benthic oligochaetes for bioassessment of inland water bodies in Sri Lanka. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental Study on the Diet of Mosquitofish (Gambusia holbrooki) under Different Ecological Conditions in a Shallow Lake
Authors: Blanco Saúl , Romo Susana , Villena María‐José
Published: June 2004

We studied the diet of the eastern mosquitofish Gambusia holbrooki with in situ experimental mesocosms located in a shallow lake. Different nutrient concentrations (phosphorus and nitrogen) and fish population densities were tested. Our results confirm that it is a planktivorous species, with also a great ingestion of algae and detritus. Nutrient fertilization caused almost no changes in this species feeding behavior, but larger mosquitofish stocks induced a shift to zooplanktivory and a decline in detritivory. When macrophytes were present, the predation effect focused on zooplankton and plant‐associated animals, otherwise predation on bottom macroinvertebrates increased. Females preyed upon almost all groups more intensely, including detritus. Males and juveniles did not overlap diet, the former being more selective on ostracods, while juveniles consumed detritus, rotifers and cladoceran. Our data support the idea that mosquitofish can cause important top‐down effects in shallow lakes under a wide variety of ecological conditions, being an important zooplanktivore in both turbid and plant‐dominated shallow lakes especially in the Mediterranean zone, where high temperatures and absence of piscivores promote maintenance of its populations during the whole year. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Effects of Zebra Mussels (Dreissena polymorpha) on the Foraging Success of Eurasian Perch (Perca fluviatilis) and Ruffe (Gymnocephalus cernuus)
Authors: Dieterich Axel , Mörtl Martin , Eckmann Reiner
Published: June 2004

Complex habitat structures can influence the foraging success of fish. Competition for food between fish species can therefore depend on the competitors' abilities to cope with structural complexity. In laboratory experiments, we comparatively assessed effects of zebra mussels (Dreissena polymorpha Pall.) on the foraging success of Eurasian perch (Perca fluviatilis L.) and ruffe (Gymnocephalus cernuus (L.)). In single‐species and mixed‐species experiments, the fish were fed caddisfly larvae (Tinodes waeneri (L.)) over complex (mussel‐covered stones) and less‐complex (bare stones) substrates. With intraspecific competition, food consumption by perch and ruffe decreased significantly when the complex substrate was used. With interspecific competition, food consumption by perch and ruffe did not change with substrate complexity, but perch clearly out‐competed ruffe on both substrates. Zebra mussel beds provide a refuge for macrozoobenthos against predation by ruffe and probably also by perch. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental Analysis of Grazing by the Mayfly Meridialaris chiloeensis on Different Successional Stages of Stream Periphyton
Authors: Díaz Villanueva Verónica , Modenutti Beatriz
Published: June 2004

In this study we determined grazing effects of the South Andean endemic mayfly Meridialaris chiloeensis on periphyton at different stages of successional development. Grazing effects were studied through a two‐factor experimental design (colonization stages X grazer density) in a stream‐side channel in spring and winter. Our results showed an absence of proportionality between grazer density and periphyton decline in response to grazers at low and intermediate levels of periphytic biomass; however, when periphyton biomass was high a direct inverse relationship was observed between post‐grazing biomass and grazer density. The relationship between periphytic algae (chlorophyll a concentration) and periphyton (total periphytic ash‐free dry mass) (C/OM index) was used as an estimation of the autotrophic fraction in the total periphyton matrix. Grazing did not alter the C/OM index indicating that both autotrophic and heterotrophic fractions of the periphyton components were reduced in the same proportion. Ordination of samples using the relative abundance of diatom species showed that herbivore effect was less evident at intermediate and late stage of colonization than at early one. These results support the statement that the outcome of the herbivore‐periphyton interaction may depend on the successional stage of the periphyton community. In spring Fragilaria pinnata relative abundance, on the basis of cell counts, was reduced by grazing and Nitzschia palea was enhanced. In the winter experiment, grazing decreased Achnanthes minutissima relative abundance. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pelagic Ciliates in a Large Mesotrophic Lake: Seasonal Succession and Taxon‐Specific Bacterivory in Lake Constance
Authors: Cleven Ernst‐Josef
Published: June 2004

The taxonomic composition of the ciliate assemblage and their taxon‐specific bacterial grazing rates in Lake Constance were investigated over the course of one year. Bacterial grazing rates were measured using natural fluorescently labelled bacteria (FLB) and compared to bacterial production. Small species such as Balanion planctonicum/Urotricha furcata and Rimostrombidium spp./Halteria sp. were the most numerous ciliates on the annual average. Larger ciliates such as Rimostrombidium lacustris and Limnostrombidium spp. contributed significantly to total ciliate biomass, but were relatively unimportant as bacterial grazers. Per capita ingestion rates ranged from 0–194 bacteria ciliate−1 h−1 and changed seasonally up to a hundredfold within a given taxon. Approximately 1% of the bacterial production were removed by the ciliate community on the annual average. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Colonization by Macroinvertebrates of Experimentally Disturbed Stones in Three Tropical Streams Differing in Size
Authors: Melo Adriano Sanches , Froehlich Claudio Gilberto
Published: June 2004

We experimentally disturbed stones in three streams of different sizes and followed the macroinvertebrate colonization process in terms of abundance, species richness and similarity over 64 days. We hypothesized that colonization in the smallest and in the largest streams would be slower than in the medium‐sized stream. The small upstream pool of colonists available in the smallest stream could restrict colonization, while in the largest stream predation by the diverse fish assemblage could restrict drifting colonists. The medium‐sized stream did not have these two constraints. We found similar colonization patterns in all three streams, leading to the rejection of the stated hypotheses. Lack of support of the original hypothesis might be due to the weakness of the two hypothesized restrictions on colonization. In addition, colonization by crawling species from undisturbed nearby patches might be of significant importance. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Diel Variations in the Vertical Distribution of Crustacean Zooplankton and Food Selection by Planktivorous Fish in a Shallow Turbid Lake
Authors: Alajärvi Erika , Horppila Jukka
Published: June 2004

The variations in the vertical migrations by zooplankton and food composition of fish in the shallow, clay‐turbid Mustionselkä basin of Lake Hiidenvesi were studied (water depth 3 m). Daphnids showed signs of reverse migration, their density in the surface layer being highest during the day. The reverse migration was probably due to predation threat by the predatory cladoceran Leptodora kindtii. Chydorus sphaericus, which was consumed especially by the day active bleak (Alburnus alburnus), showed normal vertical migration. Copepods showed no clear vertical movements. Leptodora kindtii, as well as the large herbivore Limnosida frontosa, showed no vertical migrations, but their overall abundance increased considerably during the night, indicating horizontal movement towards the open water at night. Due to the shallowness of the water, vertical migrations may not be a good predator‐avoidance strategy for the largest cladocerans, which may be able to perform horizontal migrations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bone response to a novel highly porous surface in a canine implantable chamber
Authors: Frenkel Sally R. , Jaffe William L. , Dimaano Fred , Iesaka Kazuho , Hua Tian
Published: June 2004

Long‐term survival of uncemented hip components is dependent upon successful biological fixation. This study examined a new prosthetic surface treatment consisting of a highly porous open structure of commercially pure titanium, Tritanium™ Dimensionalized Metal; its overall porosity is approximately 65–70%. With the use of an implantable chamber in dogs, the effects of this treatment on bone ingrowth and strength of attachment were compared to both titanium (overall porosity of 30–35%) and cobalt chrome beads (overall porosity of 35–40%), with and without hydroxyapatite coating. At 6 and 12 weeks, chambers were explanted and specimens underwent high‐resolution radiographic imaging and mechanical testing. At 12 weeks, Tritanium surfaces had greater bone penetration and tensile strength than remaining surface types. Over 40% of the Tritanium specimens had a tensile strength greater than 500 N, exceeding the testing capability of the servohydraulic equipment. The highly porous Tritanium surfaces allow for a far greater amount of bone ingrowth than beaded surfaces, and may create a geometry that enhances mechanical strength. Tritanium™ Dimensionalized Metal surface treatment may result in a clinically valuable implant fixation surface to induce rapid ingrowth and a strong bone–implant interface, contributing to increased implant survivorship. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 387–391, 2004
Utilizing acid pretreatment and electrospinning to improve biocompatibility of poly(glycolic acid) for tissue engineering
Authors: Boland Eugene D. , Telemeco Todd A. , Simpson David G. , Wnek Gary E. , Bowlin Gary L.
Published: June 2004

Poly(glycolic acid) (PGA) has a long history as a bioresorbable polymer. Its biocompatibility is widely accepted, yet PGA is often rejected as a soft‐tissue scaffold because of fibrous encapsulation. The goal of this study was to improve the soft‐tissue biocompatibility of PGA by producing scaffolds composed of small‐diameter fibers through electrospinning and subjecting these scaffolds to a concentrated hydrochloric acid (HCL) pretreatment. The theory is that small‐diameter fibers will elicit a reduced immune response and HCl treatment will improve cellular interactions. Scaffolds were characterized in terms of fiber diameter and pore area via image‐analysis software. Biocompatibility was assessed through a WST‐1 cell‐proliferation assay (in vitro) with the use of rat cardiac fibroblasts and rat intramuscular implantations (in vivo). Fibers produced ranged in diameter from 0.22 to 0.88 μm with pore areas from 1.84 to 13.22 μm2. The untreated scaffold composed of 0.88‐μm fibers was encapsulated in vivo and supported the lowest rates of cell proliferation. On the contrary, the acid pretreated scaffold with 0.22‐μm fibers was incorporated into the surrounding tissue and exhibited proliferation rates that exceeded the control populations on tissue‐culture plastic. In conclusion, this study has shown the ability to improve the biocompatibility of PGA through acid pretreatment of scaffolds comprised of submicron fiber diameters. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 144–152, 2004
Lysophosphatidic acid production and action: Validated targets in cancer?
Authors: Umezu‐Goto Makiko , Tanyi Janos , Lahad John , Liu Shuying , Yu Shuangxing , Lapushin Ruth , Hasegawa Yutaka , Lu Yiling , Trost Rosanne , Bevers Therese , Jonasch Eric , Aldape Ken , Liu Jinsong , James Robyn D. , Ferguson Colin G. , Xu Yong , Prestwich Glenn D. , Mills Gordon B.
Published: June 2004

The completion of the human genome project, the evolution of transcriptional profiling and the emergence of proteomics have focused attention on these areas in the pathophysiology and therapy of cancer. The role of lysophospholipids as potential mediators in cancer pathophysiology, screening and management has taken a major leap forward with the recent cloning of several enzymes involved in the metabolism of lysophospholipids. Lysophospholipids, although small molecules, contain a high “informational” content. Differences include the nature of the phosphate head group, the regiochemistry of the fatty acyl chain on the glyceryl backbone, the presence of ether versus ester linkages to the backbone, and the length and saturation of the fatty acyl or alkyl chain. This informational content is sufficient to result in a marked structure function activity relationship at their cognate receptors. Thus the emerging discipline of “functional lipidomics” is likely to prove as important as genomics and proteomics in terms of early diagnosis, prognosis, and therapy. Lysophospholipid levels are elevated in vivo in a number of pathophysiological states including ascitic fluid from ovarian cancer patients indicating a role in the pathophysiology of this devastating disease. Although controversial, levels of specific lysophospholipids may be altered in the blood of cancer patients providing a potential mechanism for early diagnosis. Several of the enzymes involved in the metabolism of lysophospholipids are aberrant in ovarian and other cancers. Further, the enzymes are active in the interstitial space, rendering them readily accessible to the effects of inhibitors including antibodies, proteins, and small molecules. In support of a role for lysophospholipids in the pathophysiology of cancer, expression of receptors for lysophospholipids is also aberrant in cancer cells from multiple different lineages. All of the cell surface receptors for lysophospholipids belong to the G protein coupled receptor family. As over 40% of all drugs in current use target this family of receptors, lysophospholipid receptors are highly “druggable.” Indeed, a number of highly specific agonists and antagonists of lysophospholipid receptors have been identified. A number are in preclinical evaluation as therapeutics. We look forward to the next several years when the role of lysophospholipids in physiology and the pathophysiology and management of cancer and other diseases are fully elucidated. © 2004 Wiley‐Liss, Inc.
L‐ascorbic acid represses constitutive activation of NF‐κB and COX‐2 expression in human acute myeloid leukemia, HL‐60
Authors: Han Seong‐Su , Kim Kihyun , Hahm Eun‐Ryeong , Lee Sook J. , Surh Young‐Joon , Park Hye K. , Kim Won S. , Jung Chul W. , Lee Mark H. , Park Keunchil , Yang Jung‐Hyun , Yoon Sung‐Soo , Riordan Neil H. , Riordan Hugh D. , Kimler Bruce F. , Park Chan H. , Lee Je‐Ho , Park Seyeon
Published: June 2004

There is increasing evidence that l‐ascorbic acid (LAA) is selectively toxic to some types of cancer cells at pharmacological concentrations, functioning as a pro‐oxidant rather than as an anti‐oxidant. However, the molecular mechanisms by which LAA initiates cellular signaling leading to cell death are still unclear. In an effort to gain insight into these mechanisms, the effects of LAA on eukaryotic transcription nuclear factor NF‐κB and cyclooxygenase‐2 (COX‐2) expression were investigated. In the present study, LAA suppressed DNA binding activity of NF‐κB, composed of a p65/p50 heterodimer, through inhibition of degradation of inhibitory κB‐α (IκB‐α) and prevention of nuclear translocation of p65. The inhibitory effect of LAA on NF‐κB activity was dependent upon glutathione levels in HL‐60 cells, as well as generation of H2O2 but not superoxide anion. LAA also downregulated the expression of COX‐2, which has a NF‐κB binding site on its promoter, through repressing NF‐κB DNA binding activity. Moreover, cotreatment of 1 μM arsenic trioxide (As2O3) with various concentrations of LAA enhanced an LAA‐induced repression of NF‐κB activity and COX‐2 expression. In conclusion, our data suggest that LAA exerts its anti‐tumor activity through downregulation of NF‐κB activity and COX‐2 expression, and these inhibitory effects can be enhanced by co‐treatment with As2O3. © 2004 Wiley‐Liss, Inc.
Effects of hydrogen peroxide on MAPK activation, IL‐8 production and cell viability in primary cultures of human bronchial epithelial cells
Authors: Pelaia Girolamo , Cuda Giovanni , Vatrella Alessandro , Gallelli Luca , Fratto Donatella , Gioffrè Vincenza , D'Agostino Bruno , Caputi Mario , Maselli Rosario , Rossi Francesco , Costanzo Francesco S. , Marsico Serafino A.
Published: June 2004

The airway epithelium is continuously exposed to inhaled oxidants, including airborne pollutants and cigarette smoke, which can exert harmful proinflammatory and cytotoxic effects. Therefore, the aim of our study was to investigate, in primary cultures of human bronchial epithelial cells (HBEC), the signal transduction pathways activated by increasing concentrations (0.25, 0.5, and 1 mM) of hydrogen peroxide (H2O2), as well as their effects on IL‐8 production and cell viability. The reported results show that H2O2 elicited, in a concentration‐dependent fashion, a remarkable increase in phosphorylation‐dependent activation of mitogen‐activated protein kinases (MAPKs), associated with a significant induction of IL‐8 synthesis and a dramatically enhanced cell death. Pre‐treatment of HBEC with MAPK inhibitors was able to significantly inhibit the effects of H2O2 on IL‐8 secretion, and to effectively prevent cell death. Therefore, these findings suggest that MAPKs play a key role as molecular transducers of the airway epithelial injury triggered by oxidative stress, as well as potential pharmacologic targets for indirect antioxidant intervention. © 2004 Wiley‐Liss, Inc.
Hypoxia‐induced erythropoietin expression in human neuroblastoma requires a methylation free HIF‐1 binding site
Authors: Rössler Jochen , Stolze Ineke , Frede Stilla , Freitag Patricia , Schweigerer Lothar , Havers Werner , Fandrey Joachim
Published: June 2004

The glycoprotein hormone Erythropoietin (EPO) stimulates red cell production and maturation. EPO is produced by the kidneys and the fetal liver in response to hypoxia (HOX). Recently, EPO expression has also been observed in the central nervous system where it may be neuroprotective. It remained unclear, however, whether EPO is expressed in the peripheral nervous system and, if so, whether a neuronal phenotype is required for its regulation. Herein, we report that EPO expression was induced by HOX and a HOX mimetic in two cell lines derived from neuroblastoma (NB), a tumor of the peripheral nervous system. Both cell lines with inducible EPO expression, SH‐SY5Y and Kelly cells, expressed typical neuronal markers like neuropeptide Y (NPY), growth‐associated protein‐43 (GAP‐43), and neuron‐specific enolase (ENO). NB cells with a more epithelial phenotype like SH‐SHEP and LAN‐5 did not show HOX inducible EPO gene regulation. Still, oxygen sensing and up‐regulation of hypoxia‐inducible factor‐1 (HIF‐1) were intact in all cell lines. We found that CpG methylation of the HIF binding site (HBS) in the EPO gene 3′ enhancer was only present in the SH‐SHEP and LAN‐5 cells but not in SH‐SY5Y and Kelly cells with regulated EPO expression. The addition of recombinant EPO to all NB cells, both under normoxic and hypoxic conditions, had no effect on cell proliferation. We conclude that the ability to respond to HOX with an increase in EPO expression in human NB may depend on CpG methylation and the differentiation status of these embryonic tumor cells but does not affect the proliferative characteristics of the cells. © 2004 Wiley‐Liss, Inc.
Paeoniflorin induces apoptosis of lymphocytes through a redox‐linked mechanism
Authors: Tsuboi Hideo , Hossain Khaled , Akhand Anwarul A. , Takeda Kozue , Du Jun , Rifa'i Muhaimin , Dai Yan , Hayakawa Akemi , Suzuki Haruhiko , Nakashima Izumi
Published: June 2004

Paeoniflorin (PF), isolated from paeony root, has been used as a herbal medicine for more than 1,200 years in China, Korea, and Japan for its anti‐allergic, anti‐inflamatory, and immunoregulatory effects. In this study, we found that PF induces apoptosis in both murine T‐lineage cells and human T‐cell leukemia Jurkat cells. This apoptosis was mediated through the reduction of mitochondrial membrane potential, activation of caspase, and fragmentation of DNA. Interestingly, PF induced generation of reactive oxygen species (ROS) and a reducing agent, dithiothreitol (DTT), and a ROS scavenger, N‐acetyl cysteine (NAC), successfully attenuated the PF‐induced apoptosis. Additionally, PF induced the phosphorylation of three mitogen‐activated protein (MAP) family kinases, extracellular signal‐regulated kinase, c‐Jun amino‐terminal kinase (JNK), and p38 MAP kinase. Curcumin, an anti‐oxidant and JNK inhibitor, inhibited PF‐induced apoptosis, suggesting the possible involvement of curcumin‐sensitive JNK or other redox‐sensitive elements in PF‐induced apoptosis. These results partially explain the action mechanism of PF‐containing paeony root as a herbal medicine. © 2004 Wiley‐Liss, Inc.