bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of magnesium on the structure and growth of GaN(0001)
Authors: Northrup John E.
Published: March 2005

First-principles total energy calculations were performed to determine the effect of Mg on the structure and growth of the GaN(0001) surface. The relative stabilities of possible Mg-rich reconstructions were determined with respect to those of the clean surface. In very Mg-rich conditions it is proposed that the surface structure comprises 12to34 ML of Mg substituting for Ga in the top layer. The stability of these structures reduces the range of Ga chemical potentials for which the Ga-bilayer is stable and therefore provides an explanation for why the window for smooth growth of GaN is narrowed when Mg is present. A structural model for the 2×2 reconstruction of the GaN(0001):Mg surface is proposed.
Study of the dominant luminescence mechanism in InGaN∕GaN multiple quantum wells comprised of ultrasmall InGaN quasiquantum dots
Authors: Lai Yen-Lin , Liu Chuan-Pu , Chen Zheng-Quan
Published: March 2005

High quality green (508nm) and blue (424nm) light emitting diodes (LEDs) from InGaN∕GaN multiple quantum wells with stable ultrasmall indium-rich clusters of 2nm and 3nm from two different nominal indium contents have been grown by metalorganic chemical vapor deposition. Comprehensive calculations including polarization, piezoelectric field, and size effect help derive an indium composition of 59% and 31% for the In-rich clusters of 2nm and 3nm, which agrees amazingly well with the asymmetric phase diagram for phase separation. From this model, we can further demonstrate that the dominant emitting mechanism for green LED is the polarization field, however, for blue LED, both the size effect and polarization effect are equally important.
Experimental verification of cumulative growth effect of second harmonics of Lamb wave propagation in an elastic plate
Authors: Deng Mingxi , Wang Ping , Lv Xiafu
Published: March 2005

Wedge transducers are used to generate and detect the primary (fundamental) waves and second harmonics of Lamb wave propagation on the surface of an elastic plate. The amplitudes of the primary waves and the second harmonics on the plate surface are measured for different separations of the transmitting and receiving wedge transducers. In the immediate vicinity of a driving frequency at which the primary and the double-frequency Lamb waves have the same phase velocities, the quantitative relationships of the second-harmonic amplitudes on propagation distance are analyzed. It is experimentally verified that the second harmonics of primary Lamb waves have a cumulative growth effect with propagation distance.
Synthesis of the First Sialic Acid Analogue Containing a y-Pyrone Moiety
Authors: Ooi Hua Chee , Sebastian B , Marcuccio M. , Jackson W. Roy , O'Keefe David F.
Published: March 2005

Oxidation of the two DANA (2-deoxy-2,3-didehydro-N-acetylneuraminic acid)
derivatives (3) and (4) by using several reagents has led to the isolation of
the first sialic acid derivative (1) containing a γ-pyrone
moiety.
Pigments of Fungi. LXII. (1S,3R)-Austrocortirubin: Isolation from the Fungus Dermocybe splendida and Synthesis from (S)-Citramalic Acid
Authors: Elsworth Catherine , Gill Melvyn , Ten Abilio
Published: March 2005

(1S,3R)-Austrocortirubin (3), a
new naturally occurring red tetrahydroanthraquinone, is isolated from the
ethanol extract of the fungus Dermocybe splendida and
its structure and stereochemistry are deduced by spectroscopic and chemical
methods and are confirmed by synthesis from
(S)-citramalic acid (10).
Resolution of a deep animal divergence by the pattern of intron conservation
Authors: Roy Scott William , Gilbert Walter
Published: March 2005

The relationship between three biologically important groups, arthropods, nematodes, and deuterostomes, remains unresolved. It is unknown whether arthropods are more closely related to nematodes (consistent with the “ecdysozoa” hypothesis) or to deuterostomes (consistent with “coelomata”). We present a method in which we use the pattern of spliceosomal intron conservation to develop a series of inequalities that characterize each possible relationship. We find that only the ecdysozoa grouping satisfies these predictions, with
P
< 10
–6
. Simulations show that our method, unlike some previous methods, is largely insensitive to rate variation between branches.
Molecular identification of potential pathogens in water and air of a hospital therapy pool
Authors: Angenent Largus T. , Kelley Scott T. , Amand Allison St. , Pace Norman R. , Hernandez Mark T.
Published: March 2005

Indoor warm-water therapy pool workers in a Midwestern regional hospital were diagnosed with non-tuberculosis pulmonary hypersensitive pneumonitis and
Mycobacterium avium
infections. In response, we conducted a multiseason survey of microorganisms present in this therapy pool water, in biofilms associated with the pool containment walls, and in air immediately above the pool. The survey used culture, microscopy, and culture-independent molecular phylogenetic analyses. Although outfitted with a state-of-the-art UV-peroxide disinfection system, the numbers of bacteria in the therapy pool water were relatively high compared with the potable water used to fill the pool. Regardless of the source, direct microscopic counts of microbes were routinely ≈1,000 times greater than conventional plate counts. Analysis of clone libraries of small subunit rRNA genes from environmental DNA provided phylogenetic diversity estimates of the microorganisms collected in and above the pool. A survey of >1,300 rRNA genes yielded a total of 628 unique sequences, the most common of which was nearly identical to that of
M. avium
strains. The high proportion of clones with different
Mycobacterium
spp. rRNA genes suggested that such organisms comprised a significant fraction of microbes in the pool water (to >30%) and preferentially partition into aerosols (to >80%) relative to other waterborne bacteria present. The results of the study strongly validate aerosol partitioning as a mechanism for disease transfer in these environments. The results also show that culture protocols currently used by public health facilities and agencies are seriously inadequate for the detection and enumeration of potential pathogens.
Antioxidants Reverse Reduction of the Human Hypoxic Ventilatory Response by Subanesthetic Isoflurane
Authors: Teppema Luc J. , Romberg Raymonda R. , Dahan Albert
Published: March 2005

Background

In subanesthetic concentrations, volatile anesthetics reduce the acute hypoxic response (AHR), presumably by a direct action on the carotid bodies but by an unknown molecular mechanism. To examine a possible involvement of reactive oxygen species or changes in redox state in this inhibiting effect, the authors studied the effect of antioxidants on the isoflurane-induced reduction of the AHR in humans.

Methods

In 10 volunteers, the authors studied the effect of antioxidants (intravenous ascorbic acid and oral alpha-tocopherol) on the reduction by isoflurane (0.12% end-tidal concentration) of the AHR on a 3-min isocapnic hypoxic stimulus (hemoglobin oxygen saturation 86 +/- 4%). All subjects participated in three separate sessions in which the effects of the antioxidants (session 1), placebo (session 2), and sham isoflurane plus antioxidants (session 3) were tested on the (sham) isoflurane-induced effect on the AHR.

Results

Isoflurane reduced the acute hypoxic response from 0.82 +/- 0.41 l . min . % to 0.49 +/- 0.23 l . min . % and from 0.89 +/- 0.43 l . min . % to 0.48 +/- 0.28 l . min . % in sessions 1 and 2, respectively (mean +/- SD; P < 0.05 vs. control). This reduction of the AHR was completely reversed by antioxidants (AHR = 0.76 +/- 0.39 l . min . %; not significantly different from control, session 1) but not by placebo in session 2 (AHR = 0.50 +/- 0.30 l . min . %; P < 005 vs. control). Sham isoflurane or antioxidants per se had no effect on the hypoxic response.

Conclusions

The data indicate that isoflurane may depress the AHR by influencing the redox state of oxygen-sensing elements in the carotid bodies. This finding may have clinical implications for patients who are prone to recurrent hypoxic episodes, e.g., due to upper airway obstruction, in the postoperative period when low-dose isoflurane may persist in the body for some time.
Does the Amygdala Mediate Anesthetic-induced Amnesia?
Authors: Alkire Michael T. , Nathan Sheila V.
Published: March 2005

Background

Amnesia for aversive events caused by benzodiazepines or propofol depends on the basolateral amygdala (BLA). Whether the amnesia of volatile anesthesia is also mediated through the BLA is unknown. If so, a general principle of anesthetic-induced amnesia may be emerging. Here, using an inhibitory avoidance paradigm, the authors determine whether BLA lesions prevent sevoflurane-induced amnesia.

Methods

Male Sprague-Dawley rats were separated into two groups: sham-operated controls (n = 22) and rats given bilateral N-methyl-D-aspartate lesions of the BLA (n = 32). After a 1-week recovery, the rats were randomly assigned to be trained during either air or sevoflurane (0.3% inspired, 0.14 minimum alveolar concentration) exposure. Animals learned to remain in the starting safe compartment of a step-through inhibitory avoidance apparatus for 100 consecutive seconds by administering foot shock (0.3 mA) whenever they entered an adjacent shock compartment. Memory was assessed at 24 h. Longer latencies to enter the shock compartment at 24 h imply better memory.

Results

Sham-air (n = 10) animals had a robust memory, with a median retention latency of 507 s (interquartile range, 270-600 s). Sham-sevoflurane (n = 6) animals were amnesic, with a latency of 52 s (27-120 s) (P < 0.01, vs. sham-air). Both the air-exposed (n = 5) and the sevoflurane-exposed (n = 8) animals with BLA lesions showed robust memory, with latencies of 350 s (300-590 s) and 378 s (363-488 s), respectively. The latencies for both did not differ from the performance of the sham-air group and were significantly greater than the latency of the sham-sevoflurane group (both P < 0.01).

Conclusions

BLA lesions block sevoflurane-induced amnesia. A role for the BLA in mediating anesthetic-induced amnesia may be a general principle of anesthetic action.
Weak Polar Interactions Confer Albumin Binding Site Selectivity for Haloether Anesthetics
Authors: Liu Renyu , Eckenhoff Roderic G.
Published: March 2005

Background

Enflurane and isoflurane are structural isomers with different anesthetic potencies and side effects. It is not clear whether these differences are produced by differing occupancy of common protein binding sites or by occupancy of different sites, but the very similar molecular properties make the latter possibility unlikely. In this study, the authors examined binding site selectivity of these anesthetics in human serum albumin (HSA).

Methods

Binding of isoflurane and enflurane with HSA was determined with isothermal titration calorimetry. Competition with known ligands (propofol) allowed localization of binding sites within the HSA molecule. Molecular properties of isoflurane and enflurane were calculated.

Results

Isoflurane binds HSA with higher affinity but smaller total enthalpy than enflurane. Enthalpogram analysis suggested that isoflurane bound a single site, whereas enflurane bound two. Competition experiments indicated that enflurane and isoflurane share one binding site, which also binds propofol. The additional enflurane site binds propofol but not isoflurane. Increased salt concentration decreased the affinity for isoflurane but not for enflurane. The dipole moment of isoflurane is higher than that of enflurane, and the isoflurane binding site is more polar.

Conclusion

These data indicate two binding sites of different character for the haloether anesthetics on HSA. One site is more polar and prefers isoflurane, presumably because of its larger dipole. The second site prefers the less polar enflurane. Therefore, weak polar interactions confer considerable selectivity, and differences in drug action may arise from occupancy of different protein sites.
Sympathetic Prions
Authors: Glatzel Markus
Published: March 2005

Transmissible spongiform encephalopathies are a group of invariably fatal neurodegenerative diseases. The infectious agent is termed prion and is thought to be composed of a modified protein (PrPSc or PrPRES), a protease-resistant conformer of the normal host-encoded membrane glycoprotein, PrPC[1]. Bovine spongiform encephalopathy, scrapie of sheep, and Creutzfeldt-Jakob disease are among the most notable transmissible spongiform encephalopathies. Prions are most efficiently propagated trough intracerebral inoculation, yet the entry point of the infectious agent is often through peripheral sites like the gastrointestinal tract[2,3]. The process by which prions invade the brain is termed neuroinvasion[4]. We and others have speculated that, depending on the amount of infectious agent injected, the injection site, and the strain of prions employed, neuroinvasion can occur either directly via peripheral nerves or first through the lymphoreticular system and then via peripheral nerves[5].
Spatial Positioning of RET and H4 Following Radiation Exposure Leads to Tumor Development
Authors: Nikiforov Yuri E.
Published: March 2005

Exposure to ionizing radiation is a well-known risk factor for a number of human cancers, including leukemia, thyroid cancer, soft tissue sarcomas, and many others. Although it has been known for a long time that radiation exposure to the cell results in extensive DNA damage, including double strand DNA breaks, the exact mechanisms of radiation-induced carcinogenesis remain unknown. Recently, a large increase in incidence of thyroid cancer was observed in children exposed to radiation after the Chernobyl nuclear accident [1]. A high prevalence of chromosomal rearrangements involving the RET gene was found among these radiation-induced thyroid tumors [2,3]. As a result of such rearrangement, a portion of the RET gene is fused with another gene, typically with the H4 or ELE1. However, since the DNA targets of ionizing radiation are randomly distributed throughout the cell nucleus, the reason for predilection for the RET rearrangements in thyroid cells was unclear.
Transgenic Killer Commensal Bacteria as Mucosal Protectants
Authors: Polonelli Luciano
Published: March 2005

As first line of defense against the majority of infections and primary site for their transmission, mucosal surfaces of the oral cavity and genitourinary, gastrointestinal, and respiratory tracts represent the most suitable sites to deliver protective agents for the prevention of infectious diseases. Mucosal protection is important not only for life threatening diseases but also for opportunistic infections which currently represent a serious burden in terms of morbidity, mortality, and cost of cures. Candida albicans is among the most prevalent causes of mucosal infections not only in immuno- compromised patients, such as HIV-infected subjects who are frequently affected by oral and esophageal candidiasis, but also in otherwise healthy individuals, as in the case of acute vaginitis. Unfortunately, current strategies for mucosal protection against candidiasis are severely limited by the lack of effective vaccines and the relative paucity and toxicity of commercially available antifungal drugs. An additional option has been reported in a recent
Global Biomonitoring of Perfluorinated Organics
Authors: Giesy John P. , Kannan Kurunthachalam , Jones Paul D.
Published: March 2005

The environmental distribution of fluorinated organic compounds (FOCs) has been less well described than the other halogenated hydrocarbons such as chlorinated and brominated compounds. This is despite the fact that FOCs have been used in a wide variety of products and applications for more than 50 years. FOCs are resistant to hydrolysis, photolysis, microbial degradation, or metabolism by vertebrates due to the high energy of carbon–fluorine bond. In particular, perfluorinated (fully fluorinated) compounds (PFCs) have the potential to persist in the environment. But, until recently, the extent and magnitude of environmental distribution of PFCs was unknown. Recent development of an analytical technique for PFCs using high performance liquid chromatography-negative ion electrospray tandem mass spectrometry (HPLC-ESMSMS)[1] permitted the survey of PFCs in livers and blood plasma of wildlife on a global scale[2].
Pesticides and Parkinson’s Disease
Authors: Sherer Todd B. , Betarbet Ranjita , Greenamyre J. Timothy
Published: March 2005

Parkinson’s disease (PD), a common neurodegenerative disorder affects approximately 1% of the population over 65. PD is a late-onset progressive motor disease characterized by tremor, rigidity (stiffness), and bradykinesia (slowness of movement). The hallmark of PD is the selective death of dopamine-containing neurons in the substantia nigra pars compacta which send their projections to the striatum and the presence of cytoplasmic aggregates called Lewy bodies [1-2]. Most cases of PD are sporadic but rare cases are familial, with earlier onset. The underlying mechanisms and causes of PD still remain unclear.
Some Deafness-Causing Mutations Can Be Silenced with the Appropriate Gene Partner
Authors: Wilcox Edward , Riazuddin Saima , Riazuddin Sheikh
Published: March 2005

Inheritance of a deafness-causing genotype does not necessarily mean that a person will have profound hearing loss. The presence of a modifying gene can change the effect of the deafness genotype. As an example, mutations found commonly among the deaf are at times found among their normal hearing relatives [1]. The implication is that there are genes or gene products whose interactions allow the normal physiological function of the inner ear despite a mutation that would normally disrupt the process. Deafness is not the first disorder in which modifiers can change the expected outcome, nor will it be the last, but it is very unusual for the outcome to be so dramatically changed.
Metamorphosis of Benthic Invertebrate Larvae: A Sensitive Indicator for Detection of Changes in Marine Environmental Quality
Authors: Zhang Xuelei
Published: March 2005

Many marine coastal ecosystems are threatened by increasing waste discharge, and bioassays are needed because chemical and physical tests alone are not sufficient to assess potential effects on aquatic biota. In light of the fact that larval metamorphosis of benthic invertebrates is usually very sensitive to environmental changes, this paper reviews sensitivity comparisons of larval metamorphosis with other common bioassays in different species and those in different developmental stages of the same species, and it discusses the potential use of larval metamorphosis as an indicator of marine environmental quality.
Modeling Possible Cooling-Water Intake System Impacts on Ohio River Fish Populations
Authors: Perry Elgin , Seegert Greg , Vondruska Joe , Lohner Timothy , Lewis Randy
Published: March 2005

To assess the possible impacts caused by cooling-water intake system entrainment and impingement losses, populations of six target fish species near power plants on the Ohio River were modeled. A Leslie matrix model was constructed to allow an evaluation of bluegill, freshwater drum, emerald shiner, gizzard shad, sauger, and white bass populations within five river pools. Site-specific information on fish abundance and length-frequency distribution was obtained from long-term Ohio River Ecological Research Program and Ohio River Sanitation Commission (ORSANCO) electrofishing monitoring programs. Entrainment and impingement data were obtained from 316(b) demonstrations previously completed at eight Ohio River power plants. The model was first run under a scenario representative of current conditions, which included fish losses due to entrainment and impingement. The model was then rerun with these losses added back into the populations, representative of what would happen if all entrainment and impingement losses were eliminated. The model was run to represent a 50-year time period, which is a typical life span for an Ohio River coal-fired power plant. Percent changes between populations modeled with and without entrainment and impingement losses in each pool were compared to the mean interannual coefficient of variation (CV), a measure of normal fish population variability. In 6 of the 22 scenarios of fish species and river pools that were evaluated (6 species × 5 river pools, minus 8 species/river pool combinations that could not be evaluated due to insufficient fish data), the projected fish population change was greater than the expected variability of the existing fish population, indicating a possible adverse environmental impact. Given the number of other variables affecting fish populations and the conservative modeling approach, which assumed 100% mortality for all entrained fish and eggs, it was concluded that the likelihood of impact was by no means assured, even in these six cases. It was concluded that in most cases, current entrainment and impingement losses at six Ohio River power plants have little or no effect at the population level.
A Process for Evaluating Adverse Environmental Impacts by Cooling-Water System Entrainment at a California Power Plant
Authors: Ehrler C.P. , Steinbeck J.R. , Laman E.A. , Hedgepeth J.B. , Skalski J.R. , Mayer D.L.
Published: March 2005

A study to determine the effects of entrainment by the Diablo Canyon Power Plant (DCPP) was conducted between 1996 and 1999 as required under Section 316(b) of the Clean Water Act. The goal of this study was to present the U.S. Environmental Protection Agency (EPA) and Central Coast Regional Water Quality Control Board (CCRWQCB) with results that could be used to determine if any adverse environmental impacts (AEIs) were caused by the operation of the plant’s cooling-water intake structure (CWIS). To this end we chose, under guidance of the CCRWQCB and their entrainment technical working group, a unique approach combining three different models for estimating power plant effects: fecundity hindcasting (FH), adult equivalent loss (AEL), and the empirical transport model (ETM). Comparisons of the results from these three approaches provided us a relative measure of confidence in our estimates of effects. A total of 14 target larval fish taxa were assessed as part of the DCPP 316(b). Example results are presented here for the kelp, gopher, and black-and-yellow (KGB) rockfish complex and clinid kelpfish. Estimates of larval entrainment losses for KGB rockfish were in close agreement (FH is approximately equals to 550 adult females per year, AEL is approximately equals to 1,000 adults [male and female] per year, and ETM = larval mortality as high as 5% which could be interpreted as ca. 2,600 1 kg adult fish). The similar results from the three models provided confidence in the estimated effects for this group. Due to lack of life history information needed to parameterize the FH and AEL models, effects on clinid kelpfish could only be assessed using the ETM model. Results from this model plus ancillary information about local populations of adult kelpfish suggest that the CWIS might be causing an AEI in the vicinity of DCPP.
Can Early Life-Stages of the Marine FishSparus auratabe Useful for the Evaluation of the Toxicity of Linear Alkylbenzene Sulphonates Homologues (LAS C10-C14) and Commercial LAS?
Authors: Hampel M. , Moreno-Garrido I. , Blasco J.
Published: March 2005

Most commercial household cleaning agents and personal care products contain the anionic surfactant linear alkylbenzene sulphonates (LAS) as the active compound. After their use they are discharged, theoretically after adequate wastewater treatment, into receiving waters finally reaching estuaries and coastal waters. Laboratory toxicity tests are useful tools in determining at which concentration a certain wastewater compound becomes hazardous for an existing group of organisms. Early life-stage toxicity tests include exposure during the most sensitive development period of the organism. In fish, this type of assay has shown to predict accurately maximum acceptable toxicant concentration (MATC) values (comprised in the range defined by the NOEC and LOEC) in fish early life-stage tests. For this reason, larvae of the seabream, Sparus aurata, were exposed to increasing concentrations of LAS homologues (C10-C14) and commercial LAS. Obtained LC50values ranged between 0.1 and 3.0 mg l-1and were compared with LC50values of previous hatching experiments with the same species. Larvae proved to be more sensitive to LAS exposure of individual homologues than eggs, except in the case of commercial LAS. LC50values can be directly employed to determine their potential risk in a concrete environment with known pollutant concentrations. Dividing the LC50value with the found homologue concentration and extrapolating with certain security factors proposed by different environmental organisms, potentially hazardous pollutant concentrations may be detected. Average estuarine or coastal LAS concentrations are generally below toxicity limits for this kind of organism, considering that the average alkyl chain length of commercial LAS is 11.6 carbon atoms.
Environmental Economics for Environmental Protection
Authors: van Ierland Ekko , Brink Corjan , Hordijk Leen , Kroeze Carolien
Published: March 2005

Environmental economics deals with the optimal allocation of production factors and correcting market failure in protecting the environment. Market failure occurs because of externalities, common property resources, and public goods. Environmental policy instruments include direct regulation, taxes/subsidies, tradable permits, deposit systems, voluntary agreements, and persuasion.

Environmental policies usually focus on one pollutant or environmental issue but may have substantial impacts on other emissions and environmental problems. Neglecting these impacts will result in suboptimal policies. We present an integrated optimisation model for determining cost-effective strategies to simultaneously reduce emissions of several pollutants from several sources, allowing for interrelations between sources and abatement options. Our integrated approach in regard to acidifying compounds and greenhouse gases will be able to provide cost-effective policy options that will result in lower overall abatement costs.

This paper shows that efficient emission reduction can be calculated, but we argue that, for transboundary air pollution and climate change, it is difficult to implement the socially optimal solution because strong incentives exist for “free-riding”. In order to implement efficient policies, international environmental agree-ments like the Gothenburg or the Kyoto Protocol are necessary to establish stable coalitions. The stability of these agreements depends on the distribution of costs and benefits over countries and on the redistribution of the gains of cooperation.
The Behaviour of134Cs,60Co, and85Sr Radionuclides in Marine Environmental Sediment
Authors: Kamel Nariman H.M.
Published: March 2005

This work describes experimental investigations and modelling studies on the sorption of radionuclides134Cs,60Co, and85Sr by certain marine sediments within Egypt. The chemical composition of the marine sediments was determined. The soluble salts were measured for the sediments and the concentrations of the released cations, Al3+, Fe3+, and Si4+, were measured for the sediment materials in 0.1 M NaClO4aqueous solution at different hydrogen ion concentrations. The two main factors that control the uptake of the radionuclides onto the sediment are the pH and the exchangeable capacities of the sediment materials. Surface complex model was used to estimate the surface charge densities and the electric surface potential of the marine sediment materials. These two parameters were calculated at the surface capacity sites of the sediment materials. The desorption of the adsorbed cations was determined by means of selective consecutive extraction tests using different chemical reagents including (1) 1 M MgCl2(pH 7), (2) 1 M ammonium oxalate (pH 3-5), (3) 0.04 M NH2OH,HCl in 25% acetic acid (pH 3-4), (4) H2O2in 5% HNO3(pH 2-3), and (5) digestion with nitric acid followed by hydrofluoric and perchloric acids (pH 2).
Recent Levels of Technetium-99 in Seawater at the West Coast of Svalbard
Authors: Gerland Sebastian , Lind Bjørn , Dowdall Mark , Kolstad Anne Kathrine
Published: March 2005

Seawater from the western coast of Svalbard was sampled in the spring and summer of 2000 to determine levels of technetium-99 (99Tc), a conservative-behaving, manmade radionuclide originating from European nuclear reprocessing plants. This paper deals with the recent levels of this radionuclide in seawater and with the link between an Arctic fjord, Kongsfjorden, and the Western Spitsbergen Current (WSC), investigated using99Tc results. By means of the WSC, the99Tc radionuclides ultimately reach the eastern Fram Strait west of Spitsbergen (the largest island of the Svalbard archipelago). Results from oceanographic modelling and sea ice observations indicate a direct coupling between Kongsfjorden and the area west of it. The findings in connection with new radionuclide results presented in this paper concur with these assumptions. Furthermore they indicate that the inner part of Kongsfjorden is also well linked to the WSC. Surface seawater from the central part of the WSC, sampled during a cruise with RV Polarstern in the summer of 2000, shows a higher level of99Tc than those measured in Kongsfjorden in spring 2000. However, all levels measured in surface water are of the same order of magnitude. Data from sampling of deeper water in the WSC area provide information pertaining to the lateral distribution of99Tc. The results, along with additional data from spring 2001, indicate that Kongsfjorden is suitable for monitoring the levels of99Tc arriving in the European Arctic and that the sheltered setting of this fjord does not necessarily provide protection against pollution from the open sea.
Genotoxicity Studies in Groundwater, Surface Waters, and Contaminated Soil
Authors: Verschaeve Luc
Published: March 2005

It is at present considered important to include biological tests in measuring programmes of environmental samples to supplement the chemical and physical parameters that are currently used. A battery of tests is therefore necessary, also within a given “endpoint” (e.g., genotoxicity), because one single test will not give all the answers to our questions. As it is not possible to include all available tests in routine screening programmes, a selection of tests should be made. According to comparative investigations, the bacterial Ames test remains very important. When no preconcentration step is involved, other bacterial tests (e.g., the umu-C and VITOTOX®tests) may be recommended. The comet assay may be used in Daphnia or human white blood cells. Further validations, comparisons, mechanistic investigations, etc. remain necessary as differences are often found between the tests that are not solely explained by differences in genetic endpoint and that therefore should further be investigated and understood.
Vertical Distribution of Ozone and Nitric Acid Vapor on the Mammoth Mountain, Eastern Sierra Nevada, California
Authors: Bytnerowicz Andrzej , Parker David R. , Padgett Pamela E.
Published: March 2005

In August and September 1999 and 2000, concentrations of ozone (O3) and nitric acid vapor (HNO3) were monitored at an elevation gradient (2184–3325 m) on the Mammoth Mountain, eastern Sierra Nevada, California. Passive samplers were used for monitoring exposure to tropospheric O3and HNO3vapor. The 2-week average O3concentrations ranged between 45 and 72 ppb, while HNO3concentrations ranged between 0.06 and 0.52 μg/m3. Similar ranges of O3and HNO3were determined for 2 years of the study. No clear effects of elevation on concentrations of the two pollutants were detected. Concentrations of HNO3were low and at the background levels expected for the eastern Sierra Nevada, while the measured concentrations of O3were elevated. High concentrations of ozone in the study area were confirmed with an active UV absorption O3monitor placed at the Mammoth Mountain Peak (September 5–14, 2000, average 24-h concentration of 56 ppb).
Comparison of Artificial Neural Network (ANN) Model Development Methods for Prediction of Macroinvertebrate Communities in the Zwalm River Basin in Flanders, Belgium
Authors: Dedecker Andy P. , Goethals Peter L.M. , De Pauw Niels
Published: March 2005

Modelling has become an interesting tool to support decision making in water management. River ecosystem modelling methods have improved substantially during recent years. New concepts, such as artificial neural networks, fuzzy logic, evolutionary algorithms, chaos and fractals, cellular automata, etc., are being more commonly used to analyse ecosystem databases and to make predictions for river management purposes. In this context, artificial neural networks were applied to predict macroinvertebrate communities in the Zwalm River basin (Flanders, Belgium). Structural characteristics (meandering, substrate type, flow velocity) and physical and chemical variables (dissolved oxygen, pH) were used as predictive variables to predict the presence or absence of macroinvertebrate taxa in the headwaters and brooks of the Zwalm River basin. Special interest was paid to the frequency of occurrence of the taxa as well as the selection of the predictors and variables to be predicted on the prediction reliability of the developed models. Sensitivity analyses allowed us to study the impact of the predictive variables on the prediction of presence or absence of macroinvertebrate taxa and to define which variables are the most influential in determining the neural network outputs.
A Throughfall Collection Method Using Mixed Bed Ion Exchange Resin Columns
Authors: Fenn Mark E. , Poth Mark A. , Arbaugh Michael J.
Published: March 2005

Measurement of ionic deposition in throughfall is a widely used method for measuring deposition inputs to the forest floor. Many studies have been published, providing a large database of throughfall deposition inputs to forests. However, throughfall collection and analysis is labor intensive and expensive because of the large number of replicate collectors needed and because sample collection and chemical analyses are required on a stochastic precipitation event-based schedule. Therefore we developed and tested a throughfall collector system using a mixed bed ion exchange resin column. We anticipate that this method will typically require only one to three samplings per year. With this method, bulk deposition and bulk throughfall are collected by a funnel or snow tube and ions are retained as the solution percolates through the resin column. Ions retained by the resin are then extracted in the same column with 2N KCl and analyzed for nitrate and ammonium. Deposition values in throughfall from conventional throughfall solution collectors and colocated ion exchange samplers were not significantly different during consecutive 3- and 4-month exposure periods at a high (Camp Paivika; >35 kg N ha-1year-1) and a low deposition (Barton Flats; 5–9 kg N ha-1year-1) site in the San Bernardino Mountains in southern California. N deposition in throughfall under mature pine trees at Camp Paivika after 7 months of exposure was extremely high (87 and 92 kg ha-1based on the two collector types) compared to Barton Flats (11 and 13 kg ha-1). A large proportion of the N deposited in throughfall at Camp Paivika occurred as fog drip, demonstrating the importance of fog deposition as an input source of N at this site. By comparison, bulk deposition rates in open areas were 5.1 and 5.4 kg ha-1at Camp Paivika based on the two collector types, and 1.9 and 3.0 kg ha-1at Barton Flats.
Chemical Analysis, Distributed Modelling and Risk Indices. Three Fundamental Pillars in Risk Assessment
Authors: Benfenati Emilio , Genah Daniel , Verro Roberto , Mazzatorta Paulo
Published: March 2005

The Risk Assessment (RA) of pollutants from contaminated sites and landfills is a major environmental issue in Europe, due to the large number of sites and to the importance of groundwater protection. The high number of contaminants and the lack of knowledge of their environmental properties and their ecotoxicological and toxicological characteristics complicate the problem. Furthermore, this information about the chemicals has to be combined with the data relative to the territory and to the targets. We will describe the problems relative to each topic involved in the process, and we will propose an integrated methodology for coping with these problems, using state-of-the-art approaches in each part of the protocol. This methodology has been applied in several real cases.
Induction of Cell Activation Processes by Low Frequency Electromagnetic Fields
Authors: Simkó Myrtill
Published: March 2005

Electromagnetic fields (EMF) such as those from electric power transmission and distribution lines (50/60 Hz) have been associated with increased risk of childhood leukemia, cancer of the nervous system, and lymphomas. Severalin vitrostudies on EMF effects were performed to clarify the existing controversies, define the risks, and determine the possible mechanisms of adverse effects. In some of these reports, the effects were related to other mechanisms of carcinogenesis. Modification in cell proliferation was observed after EMF exposure and a few reports on cytotoxic effects have also been published. This limited review gives an overview of the current results of scientific research regardingin vitrostudies on the effects of power line frequency EMF, but also cell biological mechanisms and their potential involvement in genotoxicity and cytotoxicity are discussed. Cell cycle control and signal transduction processes are included to elucidate the biochemical background of possible interactions. Exposure to EMF has been also linked to the incidence of leukemia and other tumors in some epidemiological studies and is considered as “possibly carcinogenic to humans”, but there is no well-established biological mechanism that explains such a relation. Furthermore, EMF is also shown as a stimulus for immune relevant cells (e.g., macrophages) to release free radicals. It is known that chronic activation of macrophages is associated with the onset of phagocytosis and leads to increased formation of reactive oxygen species, which themselves may cause DNA damage and are suggested to lead to carcinogenesis. To demonstrate a possible interaction between EMF and cellular systems, we present a mechanistic model describing cell activation as a major importance for cellular response.
Alteration of Tight and Adherens Junctions on 50-Hz Magnetic Field Exposure in Madin Darby Canine Kidney (MDCK) Cells
Authors: Somosy Zoltán , Forgács Zsolt , Bognár Gabriella , Horváth Katalin , Horváth Gyözo
Published: March 2005

Adherens (AJ) and tight junctions (TJ), as integrated parts of the junctional complex, are multifunctional specialized regions of the cell membrane in epithelial cells. They are responsible for cell-to-cell interactions and also have great importance in cellular signaling processes including Wnt protein-mediated signals. As electromagnetic field (EMF) exposure is known to cause alterations in the function as well as supramolecular organization of different cell contacts, our goal was to investigate the effect of 50-Hz magnetic field (MF) exposures on the subcellular distribution of some representative structural proteins (occludin, β-catenin, and cadherin) found in AJ and TJ. Additionally, cellular β-catenin content was also quantified by Western blot analysis. 50-Hz MF exposures seemed to increase the staining intensity (amount) of occludin, cadherins, and β-catenin in the junctional area of MDCK cells, while Western blot data indicated the quantity of b-catenin was found significantly decreased at both time points after EM exposures. Our results demonstrate that MF are able to modify the distribution of TJ and AJ structural proteins, tending to stabilize these cell contacts. The quantitative changes of β-catenin suggest a causative relationship between MF effects on the cell junctional complex and the Wnt signaling pathway.
Superficial Bladder Cancer Therapy
Authors: Schenkman Emmanuel , Lamm Donald L.
Published: March 2005

Bladder cancer treatment remains a challenge despite significant improvements in preventing disease progression and improving survival. Intravesical therapy has been used in the management of superficial transitional cell carcinoma (TCC) of the urinary bladder (i.e. Ta, T1, and carcinoma in situ) with specific objectives which include treating existing or residual tumor, preventing recurrence of tumor, preventing disease progression, and prolonging survival. The initial clinical stage and grade remain the main determinant factors in survival regardless of the treatment. Prostatic urethral mucosal involvement with bladder cancer can be effectively treated with Bacillus Calmette-Guerin (BCG) intravesical immunotherapy. Intravesical chemotherapy reduces short-term tumor recurrence by about 20%, and long-term recurrence by about 7%, but has not reduced progression or mortality. Presently, BCG immunotherapy remains the most effective treatment and prophylaxis for TCC (Ta, T1, CIS) and reduces tumor recurrence, disease progression, and mortality. Interferons, Keyhole-limpet hemocyanin (KLH), bropirimine and Photofrin-Photodynamic Therapy (PDT) are under investigation in the management of TCC and early results are encouraging. This review highlights and summarizes the recent advances in therapy for superficial TCC.
Cowper's Syringocele Causing Painful Haematuria in an Adult
Authors: Shaw Matthew B.K. , Cole Owen , Terry Timothy R.
Published: March 2005

A Cowper's syringocele in an adult is rare. Ten cases are reported in the world literature. The authors report a case of painful haematuria due to the presence of a Cowper's syringocele in an adult. The classification of lesions of the Cowper's gland is discussed together with common symptoms and differential diagnosis.
Natural Cytotoxicity Receptors: Pattern Recognition and Involvement of Carbohydrates
Authors: Porgador Angel
Published: March 2005

Natural cytotoxicity receptors (NCRs), expressed by natural killer (NK) cells, trigger NK lysis of tumor and virus-infected cells on interaction with cell-surface ligands of these target cells. We have determined that viral hemagglutinins expressed on the surface of virus-infected cells are involved in the recognition by the NCRs, NKp44 and NKp46. Recognition of tumor cells by the NCRs NKp30 and NKp46 involves heparan sulfate epitopes expressed on the tumor cell membrane. Our studies provide new evidence for the identity of the ligands for NCRs and indicate that a broader definition should be applied to pathological patterns recognized by innate immune receptors. Since nonmicrobial endogenous carbohydrate structures contribute significantly to this recognition, there is an imperative need to develop appropriate tools for the facile sequencing of carbohydrate moieties.
Application of MM/PBSA colony free energy to loop decoy discrimination: Toward correlation between energy and root mean square deviation
Authors: Fogolari Federico , Tosatto Silvio C.E.
Published: March 2005

Accurate free energy estimation is needed in many predictive tasks. The molecular mechanics/Poisson‐Boltzmann solvent accessible surface area (MM/PBSA) approach has proven to be accurate. However, the correlation between the estimated free energy and the distance (e.g., root mean square deviation [RMSD]) from the most stable conformation is hindered by the strong free energy dependence on minor conformational variations. In this paper, a protocol for MM/PBSA free energy estimation is designed and tested on several loop decoy sets. We show that further integration of MM/PBSA free energy estimator with the colony energy approach makes the correlation between the free energy and RMSD from the native structure apparent, for the test sets on which it could be applied. Our results suggest that (1) the MM/PBSA free energy estimator is able to detect native‐like structures for most decoy sets, and (2) application of the colony energy approach greatly hampers the MM/energy strong dependence on minor conformational changes.
The role of the 132–160 region in prion protein conformational transitions
Authors: Torrent Joan , Alvarez‐Martinez Maria Teresa , Liautard Jean‐Pierre , Balny Claude , Lange Reinhard
Published: March 2005

The native conformation of host‐encoded cellular prion protein (PrPC) is metastable. As a result of a post‐translational event, PrPC can convert to the scrapie form (PrPSc), which emerges as the essential constituent of infectious prions. Despite thorough research, the mechanism underlying this conformational transition remains unknown. However, several studies have highlighted the importance of the N‐terminal region spanning residues 90–154 in PrP folding. In order to understand why PrP folds into two different conformational states exhibiting distinct secondary and tertiary structure, and to gain insight into the involvement of this particular region in PrP transconformation, we studied the pressure‐induced unfolding/ refolding of recombinant Syrian hamster PrP expanding from residues 90–231, and compared it with heat unfolding. By using two intrinsic fluorescent variants of this protein (Y150W and F141W), conformational changes confined to the 132–160 segment were monitored. Multiple conformational states of the Trp variants, characterized by their spectroscopic properties (fluorescence and UV absorbance in the fourth derivative mode), were achieved by tuning the experimental conditions of pressure and temperature. Further insight into unexplored conformational states of the prion protein, likely to mimic the in vivo structural change, was obtained from pressure‐assisted cold unfolding. Furthermore, salt‐induced conformational changes suggested a structural stabilizing role of Tyr150 and Phe141 residues, slowing down the conversion to a β‐sheet form.
Toll‐like receptors, endogenous ligands, and systemic autoimmune disease
Authors: Rifkin Ian R. , Leadbetter Elizabeth A. , Busconi Liliana , Viglianti Gregory , Marshak‐Rothstein Ann
Published: March 2005

Summary:  The critical role of Toll‐like receptors (TLRs) as mediators of pathogen recognition by the innate immune system is now firmly established. Such recognition results in the initiation of an inflammatory immune response and subsequent instruction of the adaptive immune system, both of which are designed to rid the host of the invading pathogen. More controversial is the potential role of TLRs in the recognition of endogenous ligands and what effect this might have on the consequent development of autoimmune or other chronic sterile inflammatory disorders. An increasing number of studies implicate TLRs as being involved in the immune response to self‐molecules that have in some way been altered from their native state or accumulate in non‐physiologic sites or amounts, although questions have been raised about possible contaminants in certain of these studies. In this review, we discuss the evidence for endogenous ligand–TLR interactions with particular emphasis on mammalian chromatin, systemic lupus erythematosus, and atherosclerosis. Overall, the data support the general concept of a role for TLRs in the recognition of endogenous ligands. However, the precise details of the interactions and the extent to which they may contribute to the pathogenesis of human disease remain to be clarified.
CTLA4 gene polymorphism and autoimmunity
Authors: Gough Stephen C. L. , Walker Lucy S. K. , Sansom David M.
Published: March 2005

Summary:  CD28 and cytotoxic T‐lymphocyte antigen‐4 (CTLA4) are two receptors that have critical but opposing functions in T‐cell stimulation. CD28 promotes a number of T‐cell activities, whereas in contrast CTLA4 is an essential inhibitor of T‐cell responses. Because of its inhibitory role, CTLA4 is a strong candidate susceptibility gene in autoimmunity and several studies suggest disease‐associated polymorphisms. In this review, we discuss recent progress in relating CTLA4 polymorphisms to disease susceptibility and consider the putative mechanisms by which CTLA4 may act to inhibit autoimmunity.