bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of metformin on glutathione and magnesium in normal and streptozotocin‐induced diabetic rats
Authors: Ewis Soliman A. , Abdel‐Rahman Mohamed S.
Published: October 2006

Recently there has been growing interest in magnesium deficiency and its correlation with coronary artery disease, chronic complications of diabetes mellitus and antioxidant enzyme activity. Hypomagnesemia is a common association of diabetes mellitus, and the blood glutathione (GSH) level is significantly lower in both conditions. Metformin (Met), ‘an oral antihyperglycemic drug’ frequently used in the management of diabetes mellitus outside the USA, has been shown to have an insulin‐like action. The purpose of this study was to investigate the effect of oral administration of Met (60 mg kg−1) for 14 days on GSH and magnesium levels in blood, liver and heart of normal and streptozotocin‐induced diabetic Wistar rats. Diabetes was induced by an i.p. injection of streptozotocin (60 mg kg−1). Our results showed that Met did not affect fasting serum glucose concentration in non‐diabetic animals but reduced it significantly in diabetic animals. Serum and liver magnesium levels were significantly decreased in the untreated diabetic group compared with the normal group. Treatment with Met improved liver magnesium concentration in the diabetic group only. It has no effect on serum magnesium in diabetic or non‐diabetic rats. Heart magnesium levels showed non‐significant changes in all groups. In diabetic animals a significant decrease of GSH in both blood and liver was observed. Treatment with Met increased these levels significantly, with a similar effect on GSH levels in non‐diabetic rats. There were no significant changes in heart GSH levels in any of the groups. This study demonstrates that oral Met therapy improves the altered levels of magnesium and GSH in diabetic rats.
Dynamics and patterns of skills within small and medium‐sized enterprises
Authors: McLarty Roy , Dousios Dimitrios
Published: October 2006

The critical role of small and medium enterprises (SMEs), in impacting upon strategic activities in every modern society, has been observed and extensively researched in the literature of social and management sciences.

The dynamic business environment, in which SMEs unfold their activities, has been influenced by the forces of change and consequently many small businesses, in an attempt to preserve and protect their market position, have turned their attention to human capital as an indispensable organizational competence.

Within this context, the necessity of examining and explaining previously neglected areas of academic inquiry, like the importance of skills acquisition, arises.

The purpose of this paper is to present research principally related to the SME skills environment. The work explores new findings, providing analytical and practical tools applicable to managers within that domain and gives rise to prescriptions for SME development.

Copyright © 2006 John Wiley & Sons, Ltd.
Proteomic profiling of murine oocyte maturation
Authors: Vitale Alejandra M. , Calvert Meredith E. Kennedy , Mallavarapu Mallika , Yurttas Piraye , Perlin Julie , Herr John , Coonrod Scott
Published: October 2006

In an effort to better understand oocyte function, we utilized two‐dimensional (2D) electrophoresis and mass spectrometry to identify proteins that are differentially expressed during murine oocyte maturation. Proteins from 500 germinal vesicle (GV) and metaphase II‐(MII) arrested oocytes were extracted, resolved on 2D electrophoretic gels, and stained with silver. Analysis of the gels indicated that 12 proteins appeared to be differentially expressed between the GV and MII stage. These proteins were then cored from the 2D gels and identified by mass spectrometry as: transforming acidic coiled‐coil protein 3 (TACC3), heat shock protein 105 (HSP105), programmed cell death six‐interacting protein (PDCD6IP), stress‐inducible phosphoprotein (STI1), importin α2, adenylsuccinate synthase (ADDS), nudix, spindlin, lipocalin, lysozyme, translationally controlled tumor protein (TCTP), and nucleoplasmin 2 (NPM2). Interestingly, PDCD6IP, importin α2, spindlin, and NPM2 appear slightly larger in mass and more acidic on the MII oocyte gel compared to the GV oocyte gel, suggesting that they may be post‐translationally modified during oocyte maturation. Given NPM2 is an oocyte‐restricted protein, we chose to further investigate its properties during oocyte maturation and preimplantation development. Real‐Time RT‐PCR showed that NPM2 mRNA levels rapidly decline at fertilization. Indirect immunofluorescence analysis showed that, with the exception of cortical localization in MII‐arrested oocytes, NPM2 is localized to the nucleus of both GV stage oocytes and all stages of preimplantation embryos. We then performed one‐dimensional (1D) western blot analysis of mouse oocytes and preimplantation embryos and found that, as implicated by the 2D gel comparison, NPM2 undergoes a phosphatase‐sensitive electrophoretic mobility shift during the GV to MII transition. The slower migrating NPM2 form is also present in pronuclear embryos but by the two‐cell stage, the majority of NPM2 exists as the faster migrating form, which persists to the blastocyst stage. Mol. Reprod. Dev. 74: 608–616, 2007. © 2006 Wiley‐Liss, Inc.
Regulating p73 isoforms in human tumours
Authors: Coates PJ
Published: October 2006

Although mutations in the TP73 gene are extremely rare in human tumours, altered expression is common. In some tumours, most notably leukaemias and lymphomas, expression of TP73 is reduced, suggesting a tumour suppressor role. In contrast, TP73 is over‐expressed in many other tumour types, implying that it has oncogenic functions in human tumourigenesis. These conflicting scenarios can be reconciled by the observations that the TP73 gene produces p53‐like isoforms (TAp73) and anti‐p53 isoforms (ΔTAp73). Thus, loss of TAp73 or over‐expression of ΔTAp73 should each promote oncogenic transformation, and the balance of expression of the opposing isoforms is the crucial factor. The mechanisms that regulate expression of TP73 isoforms are therefore of great interest. Recent data provide evidence for interacting roles of ZEB1, p300, and a polymorphic 73 bp deletion in intron 1 of the human TP73 gene in this process. Importantly, alterations to the proposed regulatory pathway for controlling TP73 isoform expression in colorectal cancer are associated with adverse clinico‐pathological characteristics. Because p73 is also associated with tumour chemosensitivity, these new findings should provide prognostic information and have the potential to guide future therapeutic decisions. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Screening for prostate cancer at low PSA range: The impact of digital rectal examination on tumor incidence and tumor characteristics
Authors: Gosselaar Claartje , Roobol Monique J. , Roemeling Stijn , van der Kwast Theo H. , Schröder Fritz H.
Published: October 2006

OBJECTIVES

To compare tumor characteristics of screen‐detected prostate cancers (PCs) either by digital rectal examination (DRE) or by prostate‐specific antigen (PSA) as biopsy indication at low PSA.

METHODS

Two populations with PSA between 2.0 and 3.9 ng/ml were studied. Group‐1 was biopsied if DRE was suspicious (1st screening round, N = 1877). In group‐2 all men were offered biopsy, regardless of DRE result (side‐study in 2nd screening‐round, N = 801). We compared cancer detection rates (CDRs) and tumor characteristics.

RESULTS

In group‐1 abnormal DRE prompted biopsy in 253 (13.5%) men (236 (93.3%) actually biopsied). Forty‐nine PCs were detected, CDR 49/1877 = 2.6%. In group‐2 we found 120 cancers in 666 (83.1%) men actually biopsied, CDR = 120/801 = 15.0%. Of all cancers detected, organ confinement (clinical T2) was found in 77.5% (group‐1) and 96.6% (group‐2; of which 99 T1c). Of all PCs 46.9% in group‐1 and 15.0% in group‐2 had biopsy Gleason score (GS) ≥ 7. In the latter, 15.2% of T1cs were classified GS ≥ 7. Considering only PCs with organ confinement or GS ≥ 7 for each group, CDRs amounted to 2.0% versus 14.5% and 1.2% versus 2.3% for group‐1 and group‐2, respectively.

CONCLUSIONS

PSA‐based screening detected a considerable amount (15.2%) of potentially aggressive tumors as T1cs, but in addition large numbers of possibly insignificant cancers (T1c, GS = 6) were diagnosed. DRE seemed to detect more selectively high‐grade cancers, but also missed many of these. Considering both populations and the need to detect aggressive but confined cancers, PSA as biopsy indication outperformed DRE at the price of more biopsies (13.5% vs. 100% if all would comply). Prostate © 2006 Wiley‐Liss, Inc.
Improved electromigration failure in Al based interconnects
Authors: Kim Yong Tae , Kim Seong‐Il
Published: October 2006

Electromigration (EM) failure in Al interconnects is significantly improved by inserting a WN film between Al and the interlayer dielectric: over 90% of test samples failed with the Al/TiN/Ti interconnects, whereas the failure rate of the Al film on WN is reduced to less than 13% under the stress con‐ ditions of 9 MA/cm2 and 225 °C, and the EM lifetime is also much extended at the same conditions. Experimental results suggest that higher activation energy, no hillocks and compressive stress are responsible for the improved electromigration performance in the Al/WN interconnect. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Description of response and charge‐state distribution of poly(ether glycol)s in electrospray
Authors: Kéki Sándor
Published: October 2006

The responses and charge‐state distributions of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) (Mn = 400–1000 g/mol) at constant electrolyte concentrations (NaCl, 10−3 mol/L) in electrospray were studied as a function of the analyte concentration in the concentration range of 10−2 to 10−7 mol/L. Single charging occurred in the case of PEG and PPG with Mn = 400 g/mol. It was observed that the response changed nearly linearly with the concentration of the polymer in the low concentration region but above a certain concentration the response leveled off. Saturation of the response at higher concentrations of PEG and PPG of Mn = 1000 g/mol, where double and triple charging occurred, was also observed. Based on the equilibrium partitioning theory a model was developed to account for the response curves and charge‐state distributions of singly, doubly and triply charged adduct ions generated from solutions of PEG and PPG. The experimental and the theoretical response curves and charge‐state distributions calculated with the model are in fairly good agreement. Copyright © 2006 John Wiley & Sons, Ltd.
A simple and sensitive assay for the quantitative analysis of rivastigmine and its metabolite NAP 226‐90 in human EDTA plasma using coupled liquid chromatography and tandem mass spectrometry
Authors: Frankfort Suzanne V. , Ouwehand Mariët , van Maanen Maria J. , Rosing Hilde , Tulner Linda R. , Beijnen Jos H.
Published: October 2006

A sensitive and specific high‐performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) assay for the determination of rivastigmine and its major metabolite NAP 226‐90 is presented. A 100 µL plasma aliquot was spiked with a structural analogue of rivastigmine as internal standard (PKF214‐976‐AE‐1) and proteins were precipitated by adding 200 µL of methanol. After centrifugation a volume of 100 µL of the clear supernatant was mixed with 100 µL of methanol/water (30:70, v/v) and volumes of 25 µL were injected onto the HPLC system. Separation was acquired on a 150 × 2.0 mm i.d. Gemini C18 column using a gradient system with 10 mM ammonium hydroxide and methanol. Detection was performed by using a turboionspray interface and positive ion multiple reaction monitoring by tandem mass spectrometry. The assay quantifies rivastigmine from 0.25 to 50 ng/mL and its metabolite NAP 226‐90 from 0.50 to 25 ng/mL, using human plasma samples of 100 µL. Validation results demonstrate that rivastigmine and metabolite concentrations can be accurately and precisely quantified in human EDTA plasma. This assay is now used to support clinical pharmacologic studies with rivastigmine. Copyright © 2006 John Wiley & Sons, Ltd.
A study of theoretical depth resolution of GaAs/AlAs reference material with low energy inert‐gas ions by Monte Carlo simulation
Authors: Bando Hideaki , Tamura Keiji , Shimizu Ryuichi , Inoue Masahiko
Published: October 2006

A Monte Carlo (MC) simulation program written in C++ has been newly developed to describe the dynamic processes of depth profiling with low energy ions. This MC simulation was applied to the depth profiling of GaAs/AlAs reference material for Ne+, Ar+, and Xe+ ions to elucidate the depth resolution attained by surface analytical techniques. The result clearly predicts that there is a considerable difference between the depth resolutions estimated from the leading and trailing edges of Ne+ and Xe+ ions, whereas the difference is quite small for Ar+ ions.

Systematic investigation of the dependence of theoretical depth resolution on primary ion energy has revealed that the preferential sputtering primarily caused by the difference in energy transfer to target atoms through elastic collisions between incident ions and target atoms results in the difference between the leading and trailing edges.

The inclusion of other factors, e.g. preferential sputtering effect caused by the metallization of Al atoms on the topmost surface, etc. for further improvement of the MC simulation modeling before accommodating quantitative arguments on the depth resolution is strongly recommended. Copyright © 2006 John Wiley & Sons, Ltd.
Serotonin 1A receptor coupling to NF‐κB studied using inducible receptor expression in hippocampal neuron‐derived cells
Authors: Sobocki Tomasz , Ray Indrani , Cano‐Sanchez Patricia , Banerjee Probal , Azmitia Efrain C.
Published: October 2006

The mechanism of serotonin 1A receptor (5‐HT1A‐R) mediated activation of NF‐κB has been studied in non‐neural cells, but this pathway has not been elucidated in neuronal cells. We have used inducible expression of the 5‐HT1A‐R in the hippocampal neuron‐derived HN2 cells to analyze the coupling of this receptor to NF‐κB. A construct harboring luciferase cDNA driven by a minimal promoter under the control of an NF‐κB‐specific enhancer element was transfected into these 5‐HT1A‐R‐expressing HN2 cells. Using luciferase expression in the transfected cells, we have studied 5‐HT1A‐R agonist evoked activation of NF‐κB. Inhibition of either mitogen activated protein kinase (MAPK) pathway with PD98059 or protein kinase C (PKC) with GFX caused elevation of the basal level of NF‐κB activity but did not affect 5‐HT1A‐R mediated activation of NF‐κB. Furthermore, neither the basal level of NF‐κB nor its activation by a 5‐HT1A‐R agonist was altered by dibutyrylcAMP. Thus, the MAPK pathway and PKC cause inhibition of the basal NF‐κB activity and the 5‐HT1A‐R‐linked NF‐κB activation does not require MAPK, PKC, and cAMP. Intriguingly, Western blot analysis showed that 5‐HT1A‐R mediates activation of both CaMKII and PI‐3K. This 5‐HT1A‐R‐evoked the stimulation of CaMKII was reversed in the presence of a PI‐3K inhibitor. Therefore, the likely mechanism of 5‐HT1A‐R mediated induction of NF‐κB in neuronal cells involves activation of PI‐3K upstream of CaMKII. This reveals a novel pathway that could be crucial in the functional activity of brain neurons.
Microbiological quantitative analysis of streptomycin
Authors: Guay Roger , Janvier Richard
Published: October 2006

The streptomycin‐dependent growth characteristic of an Escherichia coli strain was used to develop a specific and quantitative detection method for streptomycin in liquid medium. In order to overcome the interference of other antimicrobial agents which may be present in the samples to be analyzed, streptomycindependent E. coli ATCC 15745 was transformed by non‐conjugative plasmid vector pBR328 encoding for ampicillin, chloramphenicol, and tetracycline resistance The parental E. coli strain retained its initial high level resistance to sulfonamides. We observed a very good correlation between E. coli/pBR328 growth, expressed as an increase in absorbance at 660 nm as a function of time, and (dihydro) streptomycin concentrations ranging from 0 to 5.0 μg per mL. The growth dependency of the test organism on streptomycin was also maintained when ampicillin (100 μg/mL), chloramphenicol (30 μg/mL), sulfisoxazole (100 m/mL), and tetracycline (30 μg/mL) were added in combination with the aminoglycoside antibiotic. This dependency was also evaluated by the determination of beta‐lactamase activity (encoded by pBR328) used as a growth marker enzyme after a 20 h incubation period of the test organism with a combination of (dihydro) streptomycin and non‐aminoglycosidic antibiotics.
Influence of physicochemical parameters on the microtox test response
Authors: Vasseur P. , Bois F. , Ferard J. F. , Rast C.
Published: October 2006

Toxicity studies are generally conducted with single chemicals under standardized conditions. Yet results with the same substances can be different if antagonistic or synergistic interactions occur with the test medium constituents. In fact the toxic response of various chemicals seems highly dependent on temperature, contact time, salinity, buffering substances and water hardness.

As Microtox test has previously been used to assess the toxicity of pure chemicals and complex effuents, it is interesting to study how some physico‐chemical interactions can modulate the response of the luminescent bacteria in this system.

In the present investigation, the effects of the test temperature and the role of pH, buffers, hardness and salinity were studied for different times of exposure of the Microtox bacterial reagent to various inorganic and organic compounds including cadmium, zinc, pentachlorophenol and benzene. The results indicated that physicochemical parameters must be considered when analyzing Microtox data of complex effuents or mixtures of chemicals.
The toxicity and mutagenicity of n‐nitroso compounds in sarcina lutea and salmonella typhimurium
Authors: Lin Jen‐Kun , Horng Tzyy‐Show
Published: October 2006

Mutants of Salmonella typhimurium have been used as tester strain in assessing the mutagenicity of various compounds. The revertants arising from the backmutation of these mutants by tested chemicals were counted and used as the measure of mutagenicity. Several N‐nitroso compounds were found to be insensitive to Salmonella system. In searching for a new microbial system for evaluating the toxicity and mutagenicity of N‐nitroso compounds, we found that the Grampositive coccoid organism Sarcina lutea is responsive to the challenge of these compounds. The wild type of Sarcina lutea is characterized by its gold yellow colony. On treating with direct‐reacting N‐nitroso compounds, Sarcina lutea produces several groups of mutants with different color of colonies such as white, pink and pale‐yellow. It seems that the mutants result from the induced mutation of the genes responsible for the synthesis of carotenoids. Several newly synthesized N‐nitroso compounds including N‐nitrosophenacetin, 2‐nitro‐N‐nitrosophenacetin, N,N′‐dimethyl‐N‐nitrosourea and nitrosated 2‐carboline derivatives were tested on this newly developed system. For the purpose of comparison, the mutagenicity of these compounds were also tested on several Salmonella typhimurium strains such as TA 97, TA 98, TA 100, TA 1538, TA 1537, and TA 1535.
Practical and theoretical aspects of the DCB assay for carcinogenic and other genotoxic agents
Authors: Kubinski H. , Kubinski Z. O.
Published: October 2006

The DNA‐cell binding (DCB) assay grew from our early studies demonstrating that in the presence of carcinogenic chemicals, radioactively labeled nucleic acids attached strongly to isolated cellular membranes and to intact prokaryotic and eucaryotic cells. A survey of over 300 chemicals revealed that this test is capable of correctly predicting carcinogenic potential in more than 95% of cases. Recently we began using formaldehyde‐treated Escherichia coli indicator cells and noted that the accuracy of prediction and the sensitivity of the test are even greater. For example, a class of noncarcinogenic, intercalating agents that showed as false positives in the original study, scored negative in this modified version of DCB test. This assay has several advantages over other rapid tests for genotoxicity, including simplicity, rapidity, economy, and reproducibility. As demonstrated by our studies on a number of diverse products, it is especially suitable for analyzing industrial and other environmental chemicals and their mixtures. The increased DNA‐cell binding is due to a property shared by most, if not all, carcinogenic agents—their ability to produce macromolecular adducts between proteins and nucleic acids, as well as inter‐ and intramolecular complexes in DNA. The latter class of adducts is responsible for inducing chromosomal transposition‐like events that we observed in a separate set of experiments using transformation of Bacillus subtilis for measuring distances between genetic markers. In these experiments markers were stably transferred to a different position on the chromosome as the result of DNA‐exposure to an ultimate carcinogen, N‐acetoxy N‐acetyl‐aminofluorene. If, as many investigators believe, the specific chromosomal translocations are the cause of neoplasia, the high predictive potential of the DCB test may be due to its capability to measure the production of specific macromolecular complexes.
The toxicity of betel nut extract determined by inhibition of microbial dehydrogenase activity
Authors: Koontongkaew Sittichai , Thaweboon Boonyanit , Tungtrongchitr Rungsunn
Published: October 2006

Dimethyl sulfoxide extracts of betel nut (100g/L) and betel leaf (100g/L), and methanol and water extracts of betel nut (100g/L) were found to inhibit dehydrogenase activity of Bacillus subtilis. In contrast betel nut (100g/L) extracted by petroleum ether showed no inhibitory effect. Thin layer chromatography, ultraviolet spectroscopy and total polyphenols estimation indicated that betel nut contained large amounts of polyphenols. On the basis of toxicity assessment, the results implied that betel nuts and betel leaves contained a hydrophilic element which was toxic to living cells.
Cytotoxin and hemolysin in diseased fish during epidemic outbreaks
Authors: Laohaviranit Laddavan
Published: October 2006

Outbreaks of fish diseases have been reported in many parts of the world. The outbreaks are difficult to control. During December 1982 and March 1983, there were severe outbreaks of fish disease in Thailand. A study on the presence and inactivation of harmful toxins, i.e., cytotoxin and hemolysin, by heat, salt and gastric pH was undertaken. Cytotoxin and hemolysin were detected in all diseased snakehead fish (Ophicephalus striatus) homogenates. Aeromonas hydrophila F 588 isolated from the diseased snakehead fish also produced cytotoxin and hemolysin. No detectable cytotoxic or hemolytic activity was found in the fish homogenates or A. hydrophila F 588 cell suspensions after heating at 100°C for 5 minutes or autoclaving at 121°C for 15 minutes at 15 lb/in.2 Cytotoxic activity remained positive in all concentrations (0% to 30% W/V) of NaCl. However, no cytotoxin could be detected when the pH of the samples was 2.0. There was a 55% decrease in hemolytic activity when A. hydrophila F 588 was incubated in 30% NaCl for 1 month at 30°C. Furthermore, there was a 50% decrease in the activity when the pH of the samples was 2.0. Hence, the diseased fish is safe for consumption if it is heated for 5 minutes at 100°C. However, it is unsafe to consume unheated salt‐fermented fish.
Cultured fish cells for the ecotoxicity testing of aquatic pollutants
Authors: Babich H. , Borenfreund E.
Published: October 2006

The volume of chemicals in everyday use that require ecotoxicity testing, the high‐costs of using whole animals for initial screenings of chemicals for their cyto‐ and genotoxicities, and the need for a ‚biological early warning signal”︁ to detect toxicants in aquatic environments have prompted the development of many microbial‐based in vitro short‐term bioassays. An area that has received relatively little study is the application of vertebrate cells, especially fish cells, for ecotoxicity testing of chemicals. From the few studies that are available it has been demonstrated that cultured, established fish cell lines can be used for (1) the in vitro cyto‐ and genotoxicity screening of known aquatic pollutants, (2) the in situ monitoring of natural waters and sediments for chemical cyto‐ and genotoxicants, and (c) elucidating structure‐activity relationships among chemicals, which can thereby serve as a biological adjunct to computer‐based mathematical predictions (QSARs) of chemical cyto‐ and genotoxicity.
Assessment for mutagenicity of 10 pharmaceutical products following ames, micronucleus, and sperm morphology testing
Authors: Stoyanov I. S. , Nicolov I. G. , Chernozemsky I. N. , Stoichev I.
Published: October 2006

Ten widely used pharmaceutical agents for which mutagenicity or carcinogenicity data are still lacking were tested in parallel with three methods: Ames' bacterial mutagenicity test (TA1535, TA1537, TA98, and TA100 Salmonella strains), micronucleus (mice BDF1), and sperm morphology abnormality (mice) tests. The groups and generic names of the tested products, all produced by Pharmachim (Bulgaria), were as follows: Psychopharmaca (Loxapinsuccinate, Medazepam hydrochloride, Nomifensinmaleate, Viloxazine hydrochloride), Vasodilatators (Nitroprussid Na, Isosorbid mononitrate, Isosorbid dinitrate), Spasmolytica (Trimetoquinol), Antirheumatica (Diclofenac Na), and the antimycotic agent Lavendotricin. In all tests, negative results were obtained. To avoid false negative results, several suggestions are made.
Effects of 2,4‐dichlorophenoxyacetic acid on Rhizobium sp. in pure culture
Authors: De Peretti A. I. Fabra , De Moro G. B. Mori , Ghittoni N. E. , De Duffard A. M. Evangelista , Duffard R. O.
Published: October 2006

The effects of 2,4‐Dichlorophenoxyacetic acid on the growth rate, chemical composition, 14C‐2,4‐dichlorophenoxyacetic acid and 45Ca2+ uptake by Rhizobium sp. M 4 able to nodulate Arachis hypogaea were determined. Cellular growth was diminished by the presence of 10−3 M 2,4‐dichlorophenoxyacetic acid in the medium. Alterations in cellular chemical composition, in 14C‐2,4‐dichlorophenoxyacetic acid and in 45Ca2+ uptake were found.
Biodegradation and adsorption of DBCP and the mathematical simulation of its transport in tropical soils
Authors: Liu Clark C. K. , Tamrakar Noor K. , Green Richard E.
Published: October 2006

Dibromochloropropane (DBCP) has been used to control nematodes since 1955 by pineapple growers in Hawaii, U.S.A. A major portion of the applied chemical eventually volatilizes to the atmosphere, but a residual amount adsorbed to soil particles may percolate downward with infiltrating water and become the source of groundwater contamination. Apart from volatilization, biodegradation is the only other means of loss of DBCP from soils. Although DBCP has been accepted as biologically stable, recent laboratory and field experiments indicate that it undergoes slow degradation in the presence of microorganisms. A numerical model was formulated and applied to simulate DBCP transport and transformation in soils. Relevant physicochemical and biological actions are incorporated in the model formulation. With values of other model parameters established independently, it was possible to evaluate the coefficients of DBCP biodegradation and adsorption by model calibration. The modeling results suggest the rate of biodegradation is greater in the top layer of the soil where the population of microorganisms is greater, and decreases as greater depths are reached. For two test fields on the island of Maui, the rate of degradation was found to be 0.00016/hr in the top 45 cm of soil, 0.00014/hr for a depth up to 90 cm, and 0.00006/hr for greater depths. The decrease of DBCP residual due to biodegradation was also found to depend on the adsorption of DBCP to soil particles. A high adsorption in the top layer of soil retards the movement of the pesticide and thus allow a significant biodegradation to take place.
Inhibition of H+ efflux and K+ uptake, and induction of K+ efflux in yeast by heavy metals
Authors: White C. , Gadd G. M.
Published: October 2006

Energy and cell membrane ATPase‐dependent H+ efflux from yeast cells was inhibited by heavy metals, which also inhibited energy‐dependent K+ uptake by the cells. Heavy metals also induced K+ efflux from metabolizing cells in two phases: reversibly at low concentrations and irreversibly at high concentrations. The concentration dependence of all of these effects varied considerably between metals.

The effect of in vivo inhibition of H+ transporting ATPases on cell membrane polarization and thus on cellular transport processes, including heavy metal uptake, are discussed. It is proposed that the inhibition of H+ efflux and the appearance of irreversible K+ efflux in yeast are potentially useful indicators of heavy metal toxicity toward yeast and possibly other fungi.
Changes of glycolipids and gangliosides in 2,4‐dichlorophenoxyacetic acid treated Chinese hamster ovary cells in monolayer culture
Authors: De Duffard Ana María Evangelista , Rivarola Viviana , Duffard Ricardo
Published: October 2006

The effects of 2,4‐dichlorophenoxyacetic acid (2,4‐D) on the growth of Chinese hamster ovary cells were studied. 2,4‐D (10−3M) had a cell growth inhibitory effect on CHO cells in monolayer cultures. When 2,4‐D was removed after four days of treatment, a rapid resumption of cell growth rate occurred. At 10−5M 2,4‐D, only a delay of growth was observed, and glycolipid and ganglioside contents were increased in both logarithmic and stationary phases of culture, while no changes in protein, cholesterol, and phospholipids were observed.
Mutagenicity studies of dioxin and related compounds with the Salmonella arabinose resistant assay system
Authors: Soler‐Niedziela L. , Ong T. , Nath J. , Zeiger E.
Published: October 2006

Components of the herbicide Agent Orange—2,4‐dichlorophenoxyacetic acid (2,4‐D) and 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T), and their esters in addition to the contaminant 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD)—and related chemicals were tested for mutagenicity using the Salmonella arabinose resistant assay system. The preincubation test using strain SV50 was performed both with and without metabolic activation. No mutagenic activity was observed for any of the chemicals tested.
Studies on the genotoxicity of dipyridyl and biphenyl derivatives using Salmonella typhimurium
Authors: Lin Jen‐Kun , Kuo Ming‐Liang , Hsu Lee‐Way
Published: October 2006

Paraquat (1,1′‐dimethyl‐4,4′‐bipyridinum dichloride) is a widely used herbicide, and the high incidence of preneoplastic lesion on the skins of the workers in a Paraquat manufactory indicates the potential genotoxicity of this compound and its derivatives. Paraquat is made from 4,4′‐dipyridyl by methylation. During the course of synthesis of 4,4′‐dipyridyl, several by‐products such as 2,2′‐, 2,3′‐, 3,3′‐, and 2,4′‐dipyridyls are formed. Some investigators have claimed that the genotoxicity of Paraquat preparation might be due to the presence of these by‐products, but detailed experimental evidence is lacking. In this article, a systematic study on the mutagenicity of these compounds, we show these compounds to be moderately mutagenic in the presence of S9 mix. Both Paraquat and 4,4′‐dipyridyl are less active in these mutagenicity assays.

Biphenyl derivatives are similar to dipyridyls in chemical configuration. Furthermore, two generally known carcinogens, 2‐acetylaminofluorene and benzidine, are biphenyl derivatives. Several related compounds including N‐acetoxy‐2‐acetylamino‐fluorene, 2 nitrofluorene, and the newly synthesized compounds N‐nitroso‐N,N′‐diacetyl‐benzidine, N‐nitrosophenacetin, and N‐nitroso‐2‐acetylaminofluorene were tested for their mutagenicities in the Salmonella system. The results indicate that N‐nitroso‐biphenyl derivatives are direct mutagens. This finding strongly suggests that nitrosation might play an important role in the activation of certain amines and amides in the living organisms.
Assessment of mutagenic activity of coastal sediments of Barcelona
Authors: Grifoll M. , Solanas A. M. , Parés R. , Centellas V. , Bayona J. M. , Albaigés J.
Published: October 2006

Organic extracts isolated from coastal sediments off Barcelona were submitted to the Salmonella/microsomal mammalian mutagenicity test (strains TA 98, 100, and 1538). The results obtained were ambiguous and a lack of dose‐response correlation was observed. However, when the extracts were resolved in fractions of increasing polarity these showed a parallel increase in mutagenicity, although the most polar were toxic. This seems to indicate that interferences among components may occur and a chemical class fractionation is needed for a better assessment of the mutagenicity of these samples.

Polycyclic aromatic hydrocarbons (benzofluoranthenes, benzo[a]pyrene, and alkyl‐substituted benzo[a]anthracenes) identified in the intermediate fractions by HRGC‐MS, could account for the mutagenicity observed. However, in the polar fractions only biogenic components (e.g., linear and steroidal alcohols and ketones) and traces of toxic xenobiotics (e.g., nonylphenol derivatives) were identified. On these grounds, it is suggested that the mutagenicity of some unknown components could be enhanced by the concurrence of the cocarcinogenic lipids found.
Relative sensitivity of algae, bacteria, invertebrates, and fish to phenol: Analysis of 234 tests conducted for more than 149 species
Authors: Walker John D.
Published: October 2006

An analysis was conducted to estimate the relative sensitivities of algae, bacteria, fish, and invertebrates to one chemical—phenol. Results from 234 studies to estimate the toxicity (EC50 or LC50 value) of phenol to 1 rotifer, 3 algal species, 4 leech species, 9 worm species, 12 fish species, 13 water mite species, 20 bivalve species, 22 crustacean species, greater than 26 bacterial species, and 39 insect species were analyzed to estimate relative, not absolute, sensitivities within and between species and between groups of species.

EC50 values from conducting ten 5‐min Microtox® tests were very similar as were EC50 values from conducting two activated sludge respiration inhibition tests. Three‐fold and thirty‐fold differences were observed for two 120‐min Motility and two Oxygen‐depletion tests, respectively. Most of the fish within‐species variability could be accounted for by differences in test temperatures. Most of the invertebrate within‐species variability could be accounted for by lab‐to‐lab or test‐to‐test variability.

Differences between bacterial tests to measure five physiological endpoints (bioluminescence, respiration, growth, dehydrogenase, motility) were estimated. Differences between the EC50 values for the two tests to measure bioluminescence were significant. However, none of the mean EC50 values from tests to measure five physiological end‐points appeared to be significantly different. Mean LC50 values from conducting fish tests were compared; only the rainbow trout and fathead minnow were significantly different.

A comparison of relative species sensitivity suggested that bluegills, daphnids, fathead minnows, featherbacks, giant gourami grass shrimp, guppies, P. phosphoreum in the 5‐min Microtox® test or rainbow trout were among the more sensitive species to the acute effects of phenol. A comparison of groups of species suggested that caddisfly or dragonfly larvae, crustaceans, daphnids, fish, shrimp and water fleas were among the more sensitive species groups to the acute effects of phenol.
Enteric viruses and coliphages in Latin America
Authors: Toranzos Gary A. , Gerba Charles P. , Hanssen Henry
Published: October 2006

Drinking and other types of waters in three Latin American countries were sampled for the presence of enteroviruses, rotaviruses, and coliphages. Large volumes of water and sewage were concentrated using a positively charged filter for the detection of enteric viruses. Statistical analyses indicated no correlation between the presence or absence of fecal coliforms, total coliforms, fecal streptococci, and viruses. Total coliforms and fecal streptococci were isolated in large numbers from pristine tropical rain forest streams, but no enteric viruses were detected in any of the same samples. All streams contaminated with sewage contained enteric viruses and high levels of indicator bacteria. These results indicate that at the present time there is no reliable indicator of the presence of viruses in waters. The presence of coliphages in waters seemed associated with fecal contamination. The large numbers of fecal streptococci and coliforms (both fecal and total) present in the waters sampled may not necessarily indicate that these waters are contaminated with fecal waste.
Pathogenic indicators in lake kinneret, Israel
Authors: Hadas Ora
Published: October 2006

The distribution of five pathogenic indicators (Fecal coliforms, Escherichia coli, enterococci, Clostridium perfringens, and F‐male specific bacteriophages) was studied at four representative sites from Lake Kinneret. Maximum bacterial and phage numbers were detected during the winter rainy season and at the Jordan River inlet. Much lower bacterial numbers were noted in the beaches and during the summer. A good correlation was achieved between bacterial occurrence and F‐male specific phages at the Alumot beach, but poor correlation was seen in the Jordan inlet.
Molluscan shellfish and water quality problems in Atlantic Canada
Authors: Menon Amar S.
Published: October 2006

This paper describes the operation of the Canadian Shellfish Sanitation Program and the impact of coastal pollution on Atlantic Canada shellfish growing areas. Criteria for the classification of shellfish growing waters in Canada are based primarily on the sanitary conditions and the bacteriological water quality of the specific growing area. Wastewater discharges to the marine environment exert great economic and social impact on the local molluscan shellfish industry in Atlantic Canada. Approximately 146,000 ha of potential shellfish producing areas are closed to shellfishing because of fecal pollution. Point source and nonpoint source pollution contribute approximately equally to shellfish growing area contaminations. Effective pollution control and management of coastal zone development are needed to protect Atlantic shellfish‐growing water quality.
Climate Change Technology Program Plan
Authors: Bierly Eugene
Published: October 2006

The U.S. Department of Energy released its Plan for Climate Change Technology Programs (CCTP) at a 20 September hearing of the U.S. House of Representatives Science Subcommittee on energy. The goal of the hearing, which was chaired by Rep. Judy Biggert (R‐Ill.), was to examine the Bush Administration's CCTP plan, review it in light of the Administration's stated goals, and determine what action might b e undertaken to implement the plan. For details of the plan, see http ://www. climatetechnology.gov/stratplan/final/index.htm
Anandamide mediates hyperdynamic circulation in cirrhotic rats via CB1 and VR1 receptors
Authors: Moezi L , Gaskari S A , Liu H , Baik S K , Dehpour A R , Lee S S
Published: October 2006

Background and purpose:

Hyperdynamic circulation and mesenteric hyperaemia are found in cirrhosis. To delineate the role of endocannabinoids in these changes, we examined the cardiovascular effects of anandamide, AM251 (CB1 antagonist), AM630 (CB2 antagonist) and capsazepine (VR1 antagonist), in a rat model of cirrhosis.

Experimental approach:

Cirrhosis was induced by bile duct ligation. Controls underwent sham operation. Four weeks later, diameters of mesenteric arteriole and venule (intravital microscopy), arterial pressure, cardiac output, systemic vascular resistance and superior mesenteric artery (SMA) flow were measured after anandamide, AM251 (with or without anandamide), AM630 and capsazepine administration. CB1, CB2 and VR1 receptor expression in SMA was assessed by western blot and RT‐PCR.

Key results:

Anandamide increased mesenteric vessel diameter and flow, and cardiac output in cirrhotic rats, but did not affect controls. Anandamide induced a triphasic arterial pressure response in controls, but this pattern differed markedly in cirrhotic rats. Pre‐administration of AM251 blocked the effects of anandamide. AM251 (without anandamide) increased arterial pressure and systemic vascular resistance, constricted mesenteric arterioles, decreased SMA flow and changed cardiac output in a time‐dependent fashion in cirrhotic rats. Capsazepine decreased cardiac output and mesenteric arteriolar diameter and flow, and increased systemic vascular resistance in cirrhotic rats, but lacked effect in controls. Expression of CB1 and VR1 receptor proteins were increased in cirrhotic rats. AM630 did not affect any cardiovascular parameter in either group.

Conclusions and implications:

These data suggest that endocannabinoids contribute to hyperdynamic circulation and mesenteric hyperaemia in cirrhosis, via CB1‐ and VR1‐mediated mechanisms.

British Journal of Pharmacology (2006) 149, 898–908. doi:10.1038/sj.bjp.0706928
Nupafant, a PAF‐antagonist prototype for suppression of ventricular fibrillation without liability for QT prolongation?
Authors: Baker K E , Wood L M , Whittaker M , Curtis M J
Published: October 2006

British Journal of Pharmacology (2006) 149, 966. doi:10.1038/sj.bjp.0706958
Thermal properties of carbon nanotube array used for integrated circuit cooling
Authors: Xu Yuan , Zhang Yi , Suhir Ephraim , Wang Xinwei
Published: October 2006

Carbon nanotubes (CNTs), owing to their exceptionally high thermal conductivity, have a potential to be employed in micro- and optoelectronic devices for integrated circuit (IC) cooling. In this study we describe a photothermal metrology intended to evaluate the thermal conductivity of a vertically aligned CNT array (VCNTA) grown on a silicon (Si) substrate. Plasma-enhanced chemical vapor deposition, with nickel (Ni) as a catalyst, was used to grow CNT. The experimentally evaluated thermal conductivity of the VCNTA and the thermal contact resistance at the interface between the VCNTA and the “hot” surface was found to be in a satisfactory agreement with theoretical predictions. The measured effective thermal resistance is measured to be 0.12∼0.16cm2∙K∕W. This resistance was compared to the measured resistance of commercially available thermal grease. Based on this comparison, we conclude that, although the thermal resistance of CNTs might not be as low as it might be desirable, there exists a definite incentive for using VCNTA of the type in question for IC cooling.
Origin of split peaks in the oscillatory magnetoresistance in AlxGa1−xN∕GaN heterostructures
Authors: Tang N. , Shen B. , Han K. , Yang Z. J. , Xu K. , Zhang G. Y. , Lin T. , Zhu B. , Zhou W. Z. , Shang L. Y. , Guo S. L. , Chu J. H.
Published: October 2006

The oscillatory magnetoresistance of the two-dimensional electron gas (2DEG) in AlxGa1−xN∕GaN heterostructures has been studied by means of magnetotransport measurements at low temperatures and high magnetic fields. The split peaks of the Shubnikov–de Haas oscillations are observed at high magnetic fields, which are attributed to the spin splitting of the 2DEG. It is found that the spin splitting energy becomes smaller with an increase in magnetic field, indicating that the Zeeman spin splitting is not dominant at measured magnetic field range. Within this magnetic field range, the zero-field spin splitting, as well as Zeeman spin splitting, affects the split peaks in the oscillatory magnetoresistance of the 2DEG in AlxGa1−xN∕GaN heterostructures.
Response to “Comment on ‘Contact mechanisms and design principles for alloyed Ohmic contacts to n-GaN’” [J. Appl. Phys. 95, 7940 (2004)]
Authors: Noor Mohammad S.
Published: October 2006

Response to Yow-Jon Lee’s comments on our article [J. Appl. Phys. 95, 7940 (2004)] describing the relative influence of thermionic emission and tunneling on the low contact resistivity of annealed Ti∕n-GaN contacts under the influence of band gap narrowing and∕or image force lowering has been presented.
Materials and devices for reduced switching field toggle magnetic random access memory
Authors: Worledge D. C. , Trouilloud P. L. , Gaidis M. C. , Lu Y. , Abraham D. W. , Assefa S. , Brown S. , Galligan E. , Kanakasabapathy S. , Nowak J. , O’Sullivan E. , Robertazzi R. , Wright G. , Gallagher W. J.
Published: October 2006

Toggle magnetic random access memory (MRAM) has been proposed to solve the problems of small switching margins and half-select activated errors found in Stoner-Wohlfarth MRAM. However, it is widely acknowledged that the switching fields required for toggle MRAM are substantially larger than those needed for Stoner-Wohlfarth MRAM. Previously published reports on toggle switching use large toggle start fields around 75Oe. Here we examine, both experimentally and with a single-domain model, how both the toggle start and end fields vary with free layer intrinsic anisotropy, thickness, width, aspect ratio, and interlayer exchange coupling. By optimizing these parameters, we obtain 400nm width devices with toggle start fields below 30Oe.
Quantum dot infrared photodetectors: Interdot coupling
Authors: Apalkov Vadim
Published: October 2006

We report on our study of the effects of interdot coupling on the properties of quantum dot infrared photodetectors. The main effect we address here is the splitting of the optical absorption of coupled quantum dots due to electron hopping between the dots. The splitting depends on the size of the dots and the interdot distance and it can be observed only for small dots, less than 20nm. The system is studied numerically within the effective mass approximation.
Magnetic properties of Zn1−zMnzGa2Se4 alloy system in the temperature range from 2to300K
Authors: Morocoima M. , Quintero M. , Quintero E. , Bocaranda P. , Ruiz J. , Moreno E.
Published: October 2006

Measurements of low field static magnetic susceptibility and of magnetization with pulsed magnetic fields up to 32T have been made as a function of temperature on polycrystalline samples of the Zn1−zMnzGa2Se4 alloy system, which has a defect tetragonal chalcopyrite structure in the whole composition range. The resulting data have been used to give information on the magnetic spin-flop and magnetic saturation transitions, and details of the magnetic B-T phase diagrams were determined for the phases. The zero-field Néel temperatures TN and triple points, for the Zn1−zMnzGa2Se4 alloy system, have been found to be 8.1K and (7.8K, 2.2T) for z=1, 5.8K and (5.6K, 1.7T) for z=0.85, 4.5K and (4.35K, 1.0T) for z=0.075, and 3.9K and (3.85K, 0.5T) for z=0.7. The susceptibility χ(T) curves for B=3 and 5T show magnetothermal effects below 4.5K.