bluuebunny/crossref_metadata_2025_split huggingface dataset:
A direct resazurin test for measuring chemical toxicity
Authors: Thomsom K. , Liu D. , Kaiser K. L. E. 
Published: October 2006

AbstractA rapid, simple, and inexpensive biochemical test for use in the mass screening of chemical compounds for toxicity was developed. The test is based on direct measurement of the inhibition of microbial dehydrogenase activity, as affected by a toxicant, in a well buffered DMSO‐resazurin solution. The addition of 5% DMSO to the reaction mixture allows the toxicity determination of compounds with low water solubility, thus facilitating measurement of the effects of important environmental contaminants on microbiota. The test has been applied to 15 selected chemicals which represent a vast range of environmental contaminants. As well as a routine screening procedure for chemical toxicity, this new resazurin test can be used as a tool in the study of structure‐activity relationship.
Testing the antimicrobial activity of compounds from the air of animal houses using the microtox test
Authors: Hartung J. 
Published: October 2006

AbstractA large number of different chemical compounds can be found in the air of densely populated animal production houses. These compounds may influence animal performance and health. Although knowledge of the biological activity of such compounds is limited in these situations, bioassays with animals are expensive, complicated to perform and evaluate. At the same time there is an increasing interest in simple and reliable test methods avoiding the use of laboratory animals. Microbial short‐term assays offer many advantages, particularly for screening purposes.The recently introduced Microtox assay was used to test the toxicity of eight single air contaminants, 13 two‐compound mixtures, and some extracts from aerosols and dust from a confined pig fattening house. p‐Cresol was the most toxic with an EC50 (15 min) value of 0.015 mM followed by m‐cresol (0.074 mM), butyric acid (0.115 mM), dimethylamine (0.156 mM), formaldehyde (0.25 mM), phenol (0.46 mM), butanol (32 mM), and acetone (258 mM). The coefficients of variation for five replicates of these compounds ranged from about 5% (m‐cresol) to 24% (dimethylamine).The two‐compound mixtures showed mainly synergistic or antagonistic effects. The investigation of the aerosol extracts showed that increasing aerosol amounts also increase the necessary dilution ratio to reach the EC50 (15 min) value. Futhermore, it was observed that the dust extract can stimulate the growth of Photobacterium phosphoreum (as determined by plate counts) although the bioluminescence is ceased. Apparently the inhibition of the light output of the bacteria is not necessarily accompanied by a loss of viability.
Comparison of cell‐free and whole cell luminescence assays in toxicity testing
Authors: Surowitz Kenneth G. , Burke Brian E. , Pfister Robert M. 
Published: October 2006

AbstractThe effects of eight organic and eight inorganic compounds on light emission by two cell‐free bioluminescent systems were compared to the effects of these substances on light emission by whole cells of Photobacterium phosphoreum (Microtox® strain). Crude luciferase preparations from the firefly (Photoniuspyralis) and Vibrio (Photobacterium) fischeri were exposed to the toxicants at or near the Microtox EC50 values for 0.25, 5, or 15 min and then reacted with the necessary reagents for luminescence (ATP for the firefly reaction; NADH, FMN and n‐decylaldehyde for the bacterial extract). The light emission values, relative to controls, were then compared to those obtained after exposure of P. phosphoreum cells to the toxicants for the same duration. The three systems were found to differ in both response time and sensitivity. The firefly extract was found to be most sensitive to inorganics while whole cells of P. phosphoreum were most sensitive to organics after 0.25 min of exposure. However, after 5 and 15 min both systems were nearly equivalent in their sensitivity to the test toxicants. The V. fishceri cell extract was found to be extremely sensitive to three of the inorganics tested at 0.25 minutes, but was either unaffected or stimulated by the remaining inorganic and organic compounds at all times examined. Our results indicate that the sensitivity of detection of certain toxic compounds may be optimized by selection of a particular luminescent system.
Genotoxicity studies on sediments using a modified SOS chromotest
Authors: Dutka B. J. , Kwan K. K. 
Published: October 2006

AbstractNoting that the inducibility of samples tested with the SOS Chromotest increased with increasing colour development time, a slightly modified Chromotest procedure was developed and applied to six sediment samples from Prince Edward Island. The samples tested by this newly developed short‐term genotoxicity test showed weak inducibility expressed by the SOSIP—SOS Inducing Potency. Five of the six samples were activated by the addition of S‐9 fraction, commonly used with the Ames/Microsome test. Only one of the samples showed toxic activity by the Microtox test.
The SOS chromotest kit: A rapid method for the detection of genotoxicity
Authors: Fish F. , Lampert I. , Halachmi A. , Riesenfeld G. , Herzberg M. 
Published: October 2006

AbstractThe SOS Chromotest is a bacterial assay for genotoxicity, based on the detection of damage to DNA as measured through the SOS DNA repair system. An E. coli strain was derived by fusing the structural lacZ gene with a promoter of one of the SOS genes, namely the sfiA gene. Auxiliary mutations increase the sensitivity of the Chromotest bacteria to genotoxic materials. In the SOS Chromotest, any damage to the DNA results in the activation of the SOS system, including the sfiA gene promoter. This, in turn, induces the de novo transcription and synthesis of the enzyme B. galactosidase. The enzyme is clearly and easily detected by a chromogenic reaction. We have miniaturized the SOS Chromotest and developed it into a self‐contained kit in the microtitration format. The kit contains all the components of the test, including dried bacteria and a dried liver S‐9 mix in a stable state, allowing on‐site operation. The whole test, including the revival of the bacteria, can be completed in 6–7 hours. In addition to being used as a genotoxics detection and monitoring system in chemical, cosmetics, food and pharmaceutical industries, the advantages of the rapid SOS Chromotest can be exploited in full for environmental and occupational health studies. In order to circumvent tedious concentrations of samples (e.g., urine, water), we have tried to further increase the sensitivity of the Chromotest by exposing the bacteria to relatively large volumes of unconcentrated samples. Employing this approach, we were able to demonstrate genotoxic activity in unconcentrated urine samples obtained from people exposed to environmental genotoxins. It appears, therefore, that the SOS Chromotest kit will allow an economically feasible and efficient monitoring of genotoxics in the environment.
Evaluation of the formazan extraction step of Int‐dehydrogenase assay
Authors: Lee C.‐W. , Koopman B. , Bitton G. 
Published: October 2006

AbstractAn essential part of in vivo INT‐dehydrogenase assay is quantitation of the intensely colored, water‐insoluble iodonitrotetrazolium formazan (INTF) that forms intracellularly as the product of INT reduction. This procedure involves extraction of INTF from microbial cells by an organic solvent, permitting colorimetric measurement of the formazan. In the present study, it was found that dimethylsulfoxide (DMSO) provided the most consistent extraction of INTF from activated sludge and filamentous bacteria. The relative efficiency of 2 + 3 tetrachloroethylene/acetone (TA) was slightly greater than that of DMSO in some cases. However, this solvent only partially extracted INTF from one of the filament types tested (type 1701) and its performance was impaired by adsorption of ferrous ion to sludge. Methanol was generally the least efficient of the solvents tested. It was particularly ineffective in extracting INTF from Fe2+‐treated sludges. Permeabilization of cells with lysozyme or Triton X‐100 improved the INTF yields obtained with methanol. Triton X‐100,the more effective of the two permeabilizing agents, increased the INTF yield obtained with methanol to the same level as that obtained with DMSO or TA.
Induction of SOS function in Escherichia coli by some mycotoxins
Authors: Auffray Y. , Boutibonnes P. 
Published: October 2006

AbstractThe genotoxic activity of 11 mycotoxins was investigated in Escherichia coli K12. The induction of the SOS function s fi A whose level of expression is monitored by means of a s fi A :: lac Z operon fusion was assayed by measuring the β‐galactosidase activity in the PQ 37 strain. Most of these fungal metabolites did not induce SOS response in this bacterial test. Only aflatoxicol, a reduced metabolite of aflatoxin B1, was well detected as an SOS inducer if metabolic activation was performed. Patulin, penicillic acid, and viomellein were only weak inducing agents. The other fungal compounds tested failed to demonstrate a positive SOS inducing activity. The relationship between the SOS Chromotest, mutagenicity to Salmonella typhimurium, and in vivo carcinogenicity was discussed.
Naturally occurring fecal coliforms and fecal streptococci in Hawaii's freshwater streams
Authors: Fujioka Roger S. , Tenno Kenneth , Kansako Sidney 
Published: October 2006

AbstractThe recreational quality of stream water in Hawaii was assessed by carefully analyzing stream, sewage, cesspool, and storm drain samples for concentrations of fecal coliform (FC), fecal streptococcus (FS), and selected physical and chemical parameters. High concentrations of FC, far in excess of the recreational water quality standard of 200 FC/100 mL, could be readily recovered from streams with no obvious sources of pollution and increased dramatically as the stream flowed through urbanized areas. Since sewage and cesspool wastes were characterized by a high (>4) FC: FS ratio, whereas stream water and storm drain samples had a low (<0.7) FC: FS ratio, it was concluded that the source of indicator bacteria in streams was not sewage or cesspool but most likely land runoff. The concentrations of indicator bacteria in treated sewage effluent being discharged into streams were determined to be much lower than the concentrations present in the receiving stream water. Thus, the impact of sewage effluent discharge into the streams of Hawaii cannot be properly evaluated by analyzing stream water samples for FC as mandated by law. Concentrations of orthophosphate, which is low in streams and high in sewage, was determined to be a reliable indicator for the presence of sewage effluent in streams.
Cervical length in women in preterm labor with intact membranes: relationship to intra‐amniotic inflammation/microbial invasion, cervical inflammation and preterm delivery
Authors: Holst R.‐M. , Jacobsson B. , Hagberg H. , Wennerholm U.‐B. 
Published: October 2006

AbstractObjectiveIntra‐amniotic infection, diagnosed by microbial invasion of the amniotic cavity (MIAC) and/or the presence of intra‐amniotic inflammation (IAI), is related to adverse perinatal outcome in women with preterm labor. Due to the subclinical nature of IAI, a correct diagnosis depends on amniocentesis, which is an invasive method not performed as a clinical routine. The aim of this study was to evaluate if cervical length measured by transvaginal sonography could assist in the identification of women at high risk for IAI.MethodsCervical length was assessed by transvaginal sonography in 87 women with singleton pregnancies in preterm labor (< 34 weeks of gestation). Cervical (n = 87) and amniotic (n = 55) fluids were collected. Polymerase chain reactions for Ureaplasma urealyticum and Mycoplasma hominis, and culture for aerobic and anaerobic bacteria, were performed. Interleukin (IL)‐6 and IL‐8 were analyzed by enzyme‐linked immunosorbent assay.ResultsIAI was present in 25/55 (45%) of the patients presenting with preterm labor who underwent amniocentesis. Women with IAI had a significantly shorter cervical length (median, 10 (range, 0–34) mm) than had those without IAI (median, 21 (range, 11–43) mm) (P < 0.0001). Receiver–operating characteristics curve analysis showed that a cervical length (cut‐off of 15 mm) predicted IAI (relative risk, 3.6; CI, 1.9–10.0) with a sensitivity of 72%, specificity of 83%, positive predictive value of 78% and negative predictive value of 78%. Cervical length was also significantly associated with preterm birth up to 7 days from sampling and at ≤ 34 weeks.ConclusionCervical length assessed by transvaginal sonography predicts IAI as well as preterm birth and could thereby be a useful clinical tool in the management of patients in preterm labor. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Diazoxide acts more as a PKC‐ɛ activator, and indirectly activates the mitochondrial KATP channel conferring cardioprotection against hypoxic injury
Authors: Kim M‐Y , Kim M J , Yoon I S , Ahn J H , Lee S H , Baik E J , Moon C‐H , Jung Y‐S 
Published: October 2006

Background and purpose:Diazoxide, a well‐known opener of the mitochondrial ATP‐sensitive potassium (mitoKATP) channel, has been demonstrated to exert cardioprotective effect against ischemic injury through the mitoKATP channel and protein kinase C (PKC). We aimed to clarify the role of PKC isoforms and the relationship between the PKC isoforms and the mitoKATP channel in diazoxide‐induced cardioprotection.Experimental approach:In H9c2 cells and neonatal rat cardiomyocytes, PKC‐ɛ activation was examined by Western blotting and kinase assay. Flavoprotein fluorescence, mitochondrial Ca2+ and mitochondrial membrane potential were measured by confocal microscopy. Cell death was determined by TUNEL assay.Key results:Diazoxide (100 μM) induced translocation of PKC‐ɛ from the cytosolic to the mitochondrial fraction. Specific blockade of PKC‐ɛ by either ɛV1‐2 or dominant negative mutant PKC‐ɛ (PKC‐ɛ KR) abolished the anti‐apoptotic effect of diazoxide. Diazoxide‐induced flavoprotein oxidation was inhibited by either ɛV1‐2 or PKC‐ɛ KR transfection. Treatment with 5‐hydroxydecanoate (5‐HD) did not affect translocation and activation of PKC‐ɛ induced by diazoxide. Transfection with wild type PKC‐ɛ mimicked the flavoprotein‐oxidizing effect of diazoxide, and this effect was completely blocked by ɛV1‐2 or 5‐HD. Diazoxide prevented the increase in mitochondrial Ca2+, mitochondrial depolarization and cytochrome c release induced by hypoxia and all these effects of diazoxide were blocked by ɛV1‐2 or 5‐HD.Conclusions and Implications:Diazoxide induced isoform‐specific translocation of PKC‐ɛ as an upstream signaling molecule for the mitoKATP channel, rendering cardiomyocytes resistant to hypoxic injury through inhibition of the mitochondrial death pathway.British Journal of Pharmacology (2006) 149, 1059–1070. doi:10.1038/sj.bjp.0706922
In vivo evidence that 5‐HT2C receptors inhibit 5‐HT neuronal activity via a GABAergic mechanism
Authors: Boothman L , Raley J , Denk F , Hirani E , Sharp T 
Published: October 2006

Background and purpose:Recent evidence suggests that 5‐HT2C receptor activation may inhibit midbrain 5‐HT neurones by activating neighbouring GABA neurones. This hypothesis was tested using the putative selective 5‐HT2C receptor agonist, WAY 161503.Experimental approach:The effect of WAY 161503 on 5‐HT cell firing in the dorsal raphe nucleus (DRN) was investigated in anaesthetised rats using single unit extracellular recordings. The effect of WAY 161503 on DRN GABA neurones was investigated using double label immunohistochemical measurements of Fos, glutamate decarboxylase (GAD) and 5‐HT2C receptors. Finally, drug occupancy at 5‐HT2A receptors was investigated using rat positron emission tomography and ex vivo binding studies with the 5‐HT2A receptor radioligand [11C]MDL 100907.Key results:WAY 161503 caused a dose‐related inhibition of 5‐HT cell firing which was reversed by the 5‐HT2 receptor antagonist ritanserin and the 5‐HT2C receptor antagonist SB 242084 but not by the 5‐HT1A receptor antagonist WAY 100635. SB 242084 pretreatment also prevented the response to WAY 161503. The blocking effects of SB 242084 likely involved 5‐HT2C receptors because the drug did not demonstrate 5‐HT2A receptor occupancy in vivo or ex vivo. The inhibition of 5‐HT cell firing induced by WAY 161503 was partially reversed by the GABAA receptor antagonist picrotoxin. Also, WAY 161503 increased Fos expression in GAD positive DRN neurones and DRN GAD positive neurones expressed 5‐HT2C receptor immunoreactivity.Conclusions and implications:These findings indicate that WAY 161503 inhibits 5‐HT cell firing in the DRN in vivo, and support a mechanism involving 5‐HT2C receptor‐mediated activation of DRN GABA neurones.British Journal of Pharmacology (2006) 149, 861–869. doi:10.1038/sj.bjp.0706935
Water status and growth phenology of a Saharan shrub in north Africa
Authors: Abdallah Lotfi , Chaieb Mohamed 
Published: October 2006

AbstractAn experimental study of the relationship between the phenological phases, water relations and climatic conditions was conducted on one shrub species, Spartidium saharae, in Saharan ecosystem of southern Tunisia. The results show that the water potential remained significantly higher than that recorded in other desert shrubs. However, a relationship between the water potential of S. saharae and precipitation was not evident suggesting that access to permanent ground water may be a factor of this decoupling. Although shoot elongation of the species occurred outside the wet season, water shortage induced a decrease in fruit production.
Assessment of α1‐adrenoceptor antagonists in benign prostatic hyperplasia based on the receptor occupancy theory
Authors: Ito Kaori , Ohtani Hisakazu , Sawada Yasufumi 
Published: October 2006

AimsTo assess the mechanistic relationship between doxazosin (α1‐receptor antagonist) and receptor occupancy and a measure of pharmacological effect (Qmax, the maximum urinary flow rate) and to compare the mean receptor occupancy ratio at clinical doses of doxazosin, tamsulosin, terazosin and prazosin in benign prostatic hyperplasia (BPH).MethodsA ternary complex model, which described the mechanism of α1‐receptor antagonists, was fitted to the pharmacological effects and receptor occupancy ratio data for doxazosin (standard tablet). In addition, mean receptor occupancy was calculated for other α1‐receptor antagonists and the optimal receptor occupancy was evaluated. The clinical pharmacological effects of the controlled release formulation of doxazosin (doxazosin GITS) were estimated based on the receptor occupancy.ResultsThe mechanistic based model was able to describe the pharmacological effects of doxazosin. Regardless of the plasma concentrations or clinical dose of each drug, the results suggest that receptor occupancy is useful to assess quantitatively and compare the pharmacological effects of drugs with similar mechanisms of action. The clinical dosage for doxazosin GITS was estimated to be at least 8 mg and the stable pharmacological effect is expected based on the estimated receptor occupancy.ConclusionsA model for Qmax improvement in BPH based on the receptor occupancy theory was able to describe the clinical effects of the α1‐receptor antagonists. Receptor occupancy is a useful index for predicting the clinical effects of α1‐receptor antagonists.
Herbivory and plant growth rate determine the success of El Niño Southern Oscillation‐driven tree establishment in semiarid South America
Authors: HOLMGREN MILENA , LÓPEZ BERNAT C. , GUTIÉRREZ JULIO R. , SQUEO FRANCISCO A. 
Published: October 2006

AbstractWhile climatic extremes are predicted to increase with global warming, we know little about the effect of climatic variability on biome distribution. Here, we show that rainy El Niño Southern Oscillation (ENSO) events can enhance tree recruitment in the arid and semiarid ecosystems of north‐central Chile and northwest Peru. Tree‐ring studies in natural populations revealed that rainy El Niño episodes have triggered forest regeneration in Peru. Field experiments indicate that tree seedling recruitment in Chile is much less successful than in Peru due mostly to larger mortality caused by herbivores. The dramatic impact of herbivores in Chile was derived from the combined result of slower plant growth and the presence of exotic herbivores (European rabbits and hares). The interplay of herbivory and climatic effects we demonstrated implies that rainy ENSO events may represent ‘windows of opportunity’ for forest recovery if herbivore pressure is minimized at the right moment.
Schistosoma japonicum egg antigens stimulate CD4+ CD25+ T cells and modulate airway inflammation in a murine model of asthma
Authors: Yang Jianghua , Zhao Jiaqing , Yang Yanfeng , Zhang Lei , Yang Xue , Zhu Xiang , Ji Minjun , Sun Nanxiong , Su Chuan 
Published: October 2006

SummaryA number of epidemiological and clinical studies have suggested an inverse association between allergy and helminth infection, such as Schistosomiasis. Therefore, we hypothesize that Schistosoma japonicum egg antigens, a type of native antigen, can induce production of CD4+ CD25+ T cells with regulatory activity, modulating airway inflammation and inhibiting asthma development. The frequency of CD4+ CD25+ T cells was determined by flow cytometry for mice treated with ovalbumin (OVA), CD25+ depletion/OVA, schistosome egg antigens, schistosome egg antigens/OVA and for control mice. The ability of CD25+ T cells from these mice to suppress T‐cell proliferation and cytokine production was investigated both in vivo and in vitro. Results showed that the CD4+ CD25+ T cells of OVA‐treated mice exhibited impaired control of dysregulated mucosal T helper 2 responses compared to the controls (P < 0·05). Depletion of CD25+ cells accelerated OVA‐induced airway inflammation and increased the expression of interleukin (IL)‐5 and IL‐4. Treatment with schistosome egg antigens increased the number and suppressive activity of CD4+ CD25+ T cells, which made IL‐10, but little IL‐4. In a murine model of asthma, S. japonicum egg antigens decreased the expression of Th2 cytokines, relieved antigen‐induced airway inflammation, and inhibited asthma development. Thus, we provided evidence that S. japonicum egg antigens induced the production of CD4+ CD25+ T cells, resulting in constitutive immunosuppressive activity and inhibition of asthma development. These results reveal a novel form of protection against asthma and suggest a mechanistic explanation for the protective effect of helminth infection on the development of allergy.
Micronutrient interventions and HIV infection: a review of current evidence
Authors: Friis Henrik 
Published: October 2006

SummaryObjective  To review the current evidence on the role of micronutrient supplementation in HIV transmission and progression.Method  Literature review.Results  The importance of micronutrients in the prevention and treatment of childhood infections is well known, and evidence is emerging that micronutrient interventions may also affect HIV transmission and progression.Conclusion  Interventions to improve micronutrient intake and status could contribute to a reduction in the magnitude and impact of the global HIV epidemic. However, more research is needed before specific recommendations can be made.