Home About us Contact
|
Home About us Contact | ||
|
|
||
Toxic Agents (toxic + agent)
Selected AbstractsThe fruit fly PUB: a phagostimulation unit bioassay system to quantitatively measure ingestion of baits by individual fliesJOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2004D. Nestel Abstract:, A bioassay to investigate quantitative phagostimulation and ingestion physiology of baits on individual fruit flies is presented. The study was undertaken using two fruit fly species: the Mediterranean fruit fly (Ceratitis capitata), a cosmopolitan insect pest, and the Ethiopian fruit fly (Dacus ciliatus), a quarantine insect in Israel. Our model bait suspension included spinosad as the toxic agent, and 1% yeast hydrolysate with 10% sucrose as phagostimulant. A preliminary toxicology study showed that the two fruit flies are highly sensitive to low concentrations of spinosad baited with this phagostimulant. The maximum concentration needed to kill 90% of the female flies was 4.2 and 8.5 p.p.m. for C. capitata and D. ciliatus, respectively. The bioassay was able to detect the ingestion of low volumes (e.g. 1 ,l) of tested solutions. The bioassay was also able to detect differences in intake of different concentrations of spinosad solutions and relate ingestion to fruit fly mortality. Additionally, the bioassay was sensitive enough to highlight differences in intake related to the physiological status of the fruit fly and fly species. The bioassay can also be used to follow ingestion kinetics of baits. We expect that this bioassay will contribute in the exploration of more efficient bait systems for fruit flies. [source] Toxicogenomics: a pivotal piece in the puzzle of toxicological researchJOURNAL OF APPLIED TOXICOLOGY, Issue 4 2007Elisavet T. Gatzidou Abstract Toxicogenomics, resulting from the merge of conventional toxicology with functional genomics, being the scientific field studying the complex interactions between the cellular genome, toxic agents in the environment, organ dysfunction and disease state. When an organism is exposed to a toxic agent the cells respond by altering the pattern of gene expression. Genes are transcribed into mRNA, which in turn is translated into proteins that serve in a variety of cellular functions. Toxicogenomics through microarray technology, offers large-scale detection and quantification of mRNA transcripts, related to alterations in mRNA stability or gene regulation. This may prove advantageous in toxicological research. In the present review, the applications of toxicogenomics, especially to mechanistic and predictive toxicology are reported. The limitations arising from the use of this technology are also discussed. Additionally, a brief report of other approaches, using other -omic technologies (proteomics and metabonomics) that overcome limitations and give global information related to toxicity, is included. Copyright © 2007 John Wiley & Sons, Ltd. [source] Neurotoxic species in prion disease: a role for PrP isoforms?JOURNAL OF NEUROCHEMISTRY, Issue 5 2007Christopher F. Harrison Abstract Prion diseases such as bovine spongiform encephalopathy in cattle and Creutzfeldt,Jakob disease in humans are associated with the misfolding and accumulation of an abnormal conformation of the host-encoded prion protein (PrP). Despite intensive research efforts conducted on PrP, the toxic agent involved in neurodegeneration is as yet unidentified. Several potential candidates have been proposed, each of which may be relevant to subsets of the broad array of prion diseases. In this study, we review current knowledge on neurotoxic PrP species, including the importance of a central hydrophobic domain for mediating neurotoxicty. [source] Chemoprotective effect of plant phenolics against anthracycline-induced toxicity on rat cardiomyocytes.PHYTOTHERAPY RESEARCH, Issue 7 2004Part III. Abstract Flavonoids are found universally in plants and act as free radical scavenging and chelating agents with antiin,ammatory, antiischemic, vasodilating and chemoprotective properties. In this study, the antilipoperoxidative and cytoprotective effects of apigenin, baicalein, kaempferol, luteolin and quercetin against doxorubicin-induced oxidative stress were investigated in isolated rat heart cardiac myocytes, mitochondria and microsomes. After preincubation of cardiomyocytes with the test compounds for 1 h the cardiomyocytes were treated with the toxic agent, doxorubicin (100 µM for 8 h). Cardiomyocyte protection was assessed by extracellular LDH and cellular ADP and ATP production. Cytoprotection was concentration dependent for baicalein > luteolin , apigenin > quercetin > kaempferol. All test compounds had signi,cantly better protective effects than dexrazoxan, an agent currently used for adjuvant therapy during anthracycline antibiotic therapy. In microsomes/mitochondria the IC50 values of lipid peroxidation inhibition for quercetin, baicalein, kaempferol, luteolin, and apigenin were 3.1 ± 0.2/8.2 ± 0.6, 3.3 ± 0.3/9.6 ± 0.5, 3.9 ± 0.3/10.1 ± 0.8, 22.9 ± 1.7/18.2 ± 0.7, and 338.8 ± 23.1/73.1 ± 6.4 mM, respectively. The antilipoperoxidative activity of apigenin differed from its cytoprotective effects, but correlated with the free radical scavenging of 2,2-diphenyl-1-picrylhydrazyl radical and half peak oxidation potential (Ep/2). Apigenin was the least effective of the ,avonoids studied in all models except the cardiomyocyte model where its cardiomyocyte cytoprotective effect was comparable to other compounds. Copyright © 2004 John Wiley & Sons, Ltd. [source] Susceptibility of the pine processionary caterpillar Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae) toward ,-endotoxins of Bacillus thuringiensis under laboratory conditionsANNALS OF APPLIED BIOLOGY, Issue 3 2001A B SHEVELEV Summary A series of natural crystal proteins from B. thuringiensis subsp. Alesti 12,25, caucasicus, galleriae 11,67, galleriae 6,96, kenyae, and shondungensis and spore-crystal preparations from finitimus 11,66 and from a recombinant strain of B. thuringiensis subsp. kurstaki expressing Cry 1 Ga1 only, were assessed as a toxic agent for the pine processionary caterpillar, Thaumetopoea pityocampa. Some preparations had a thoroughly investigated composition and contained Cry1Aa, Cry1Ab2, Cry1Ab7, Cry1D, Cry1F, Cry 1 Ga1, Cry9Aa, Cry26 crystal proteins, whereas crystals of B. thuringiensis subsp. caucasicus, kenyae, and shondungensis harboured predominantly unidentified toxins distant from commonly used prototypes. Bioassays were based on the simultaneous assignment of each treatment to groups of 20 full sibling first-instar larvae, obtained from broods of a population from North-western Italy. The toxin was applied to pine needles by the leaf dipping method and the effect was registered in both feeding inhibition and mortality. B. thuringiensis subsp. caucasicus, kenyae, galleriae 6,96, alesti, and galleriae 11,67 gave the best results in terms of both feeding inhibition and larval mortality. Broods tested in B. thuringiensis bioassays showed a substantial variation in susceptibility to the toxins, suggesting the potential development of resistance in the population. [source] A novel and sensitive test for rapid determination of water toxicityENVIRONMENTAL TOXICOLOGY, Issue 3 2002S. Ulitzur Abstract The performance of a novel, rapid, and sensitive test for detecting chemical toxicants in water is described in this article. The bioassay utilizes a highly sensitive variant of the luminescent bacterium Photobacterium leiognathi that allows the detection in water at levels below milligrams per liter of diverse groups of toxicants, including heavy metals, pesticides, PCBs, polycyclic aromatic hydrocarbons, and fuel traces. For most toxic agents reported in this study, the new assay was markedly more sensitive than the MicrotoxÔVibrio fischeri assay according to the bacterial bioluminescence toxicity data reported in the literature. Additional features of the new bioassay include the ability to discriminate between cationic heavy metals and organic toxicants and the option of being run at ambient temperatures (18°C,27°C), thereby enabling on-site testing with low-cost luminometers. In addition, the stability of the freeze-dried bacterial reagent preparation at ambient temperatures precludes the need for refrigeration or freezing during shipment, which contributes to further reducing overall operational costs. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 291,296, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10060 [source] Statistical issues on the determination of the no-observed-adverse-effect levels in toxicologyENVIRONMETRICS, Issue 4 2001Takashi Yanagawa Abstract The determination of a safe exposure level for toxic agents, often defined as the highest dose level with no toxic effect and termed the no-observed-adverse-effect level (NOAEL) is reviewed. The conventional methods based on statistical tests are criticized, particularly when the sample size is small, and an alternative method, which is based on the Akaike information criterion (AIC), is discussed. The method is extended to the estimation of the NOAEL for continuous data. Computer programs for Windows 95/NT for determining the NOAEL by the AIC approach are developed and its application to practical data is illustrated with examples. Copyright © 2001 John Wiley & Sons, Ltd. [source] Toxicogenomics: a pivotal piece in the puzzle of toxicological researchJOURNAL OF APPLIED TOXICOLOGY, Issue 4 2007Elisavet T. Gatzidou Abstract Toxicogenomics, resulting from the merge of conventional toxicology with functional genomics, being the scientific field studying the complex interactions between the cellular genome, toxic agents in the environment, organ dysfunction and disease state. When an organism is exposed to a toxic agent the cells respond by altering the pattern of gene expression. Genes are transcribed into mRNA, which in turn is translated into proteins that serve in a variety of cellular functions. Toxicogenomics through microarray technology, offers large-scale detection and quantification of mRNA transcripts, related to alterations in mRNA stability or gene regulation. This may prove advantageous in toxicological research. In the present review, the applications of toxicogenomics, especially to mechanistic and predictive toxicology are reported. The limitations arising from the use of this technology are also discussed. Additionally, a brief report of other approaches, using other -omic technologies (proteomics and metabonomics) that overcome limitations and give global information related to toxicity, is included. Copyright © 2007 John Wiley & Sons, Ltd. [source] Poisoning in Zimbabwe: a survey of eight major referral hospitalsJOURNAL OF APPLIED TOXICOLOGY, Issue 2 2002D. Tagwireyi Abstract A retrospective study of the pattern of poisoning cases admitted to eight major urban referral hospitals in Zimbabwe over a 2-year period (1998,1999 inclusive) was conducted to describe the pattern of poisoning at these centres. There were a total of 2764 hospital admissions due to poisoning, involving a total of 2846 toxic agents. Accidental poisoning (AP) and deliberate self-poisoning (DSP) accounted for 48.9% (1352 cases) and 41.3% (1142 cases), respectively. With AP, the highest number of cases (45.9%) occurred in children below the age of 5 years, with half of these due to chemicals, mainly paraffin. In the DSP group, however, more than 60% of all cases occurred in the 16,25-year age group. In addition, twice as many females as males were admitted for DSP compared with an overall male/female ratio of 1 : 1.2. Pesticides (31.4%) and pharmaceuticals (30.4%) were the most common groups of toxic agents responsible for the hospital admissions. Unknown toxins, natural toxins and pesticides showed the highest mortality rates (15.4%, 8.3% and 6.7%, respectively). Compared with the last major survey of poisoning in Zimbabwe, the pattern of poisoning at referral hospitals has changed over the last decade, with an increase in pesticide and pharmaceutical cases and a marked fall in cases of traditional medicine poisoning. Educational and legislative interventions may be required to address these changes. There is the need also to investigate further the high mortality rates associated with traditional medicine poisoning. Copyright © 2002 John Wiley & Sons, Ltd. [source] Voltage-dependent ebselen and diorganochalcogenides inhibition of 45Ca2+ influx into brain synaptosomesJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 3 2003M. B. Moretto Abstract By mediating the Ca2+ influx, Ca2+ channels play a central role in neurotransmission. Chemical agents that potentially interfere with Ca2+ homeostasis are potential toxic agents. In the present investigation, changes in Ca2+ influx into synaptosomes by organic forms of selenium and tellurium were examined under nondepolarizing and depolarizing conditions induced by high KCl concentration (135 mM) or by 4-aminopyridine (4-AP). Under nondepolarizing conditions, ebselen (400 ,M) increased Ca2+ influx; diphenyl ditelluride (40,400 ,M) decreased Ca2+ in all concentrations tested; and diphenyl diselenide decreased Ca2+ influx at 40 and 100 ,M, but had no effect at 400 ,M. In the presence of KCl as depolarizing agent, ebselen and diphenyl ditelluride decreased Ca2+ influx in a linear fashion. In contrast, diphenyl diselenide did not modify Ca2+ influx into isolated nerve terminals. In the presence of 4-AP (3 mM) as depolarizing agent, ebselen (400 ,M) caused a significant increase, whereas diphenyl diselenide and diphenyl ditelluride inhibited Ca2+ influx into synaptosomes. The results can be explained by the fact that the mechanism through which 4-AP and high K+ induced elevation of intracellular Ca2+ is not exactly coincident. The mechanism by which diphenyl ditelluride and ebselen interact with Ca2+ channel is unknown, but may be related to reactivity with critical sulfhydryl groups in the protein complex. The results of the present study indicate that the effects of organochalcogenides were rather complex depending on the condition and the depolarizing agent used. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:154,160, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10073 [source] Fractionation of Caseins by Anion-exchange Chromatography Using Food-grade BuffersJOURNAL OF FOOD SCIENCE, Issue 5 2003K.N. Turhan ABSTRACT : Caseins prepared by microfiltration of bovine skim milk were fractionated using anion-exchange chromatography. Laser densitometry of electrophoresis gels was shown to be sufficiently quantitative to perform accurate mass balance calculations detailing the fate of each casein fraction. L-cysteine was successfully used as a reducing agent instead of traditional toxic agents, such as dithiothreitol or ,-mercaptoethanol, enabling development of the first food-grade buffer system for casein fractionation. More salt was required for elution of the casein fractions having a greater charge: ,s -casein > ,-casein > ,-casein. Increasing flow rate decreased the extent of separation. Use of smaller beads was suggested as a method to maintain separation at increased flow rate. [source] A cremophor-free formulation for tanespimycin (17-AAG) using PEO- b -PDLLA micelles: Characterization and pharmacokinetics in ratsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2009May P. Xiong Abstract Tanespimycin (17-allylamino-17-demethoxygeldanamycin or 17-AAG) is a promising heat shock protein 90 inhibitor currently undergoing clinical trials for the treatment of cancer. Despite its selective mechanism of action on cancer cells, 17-AAG faces challenging issues due to its poor aqueous solubility, requiring formulation with Cremophor EL (CrEL) or ethanol (EtOH). Therefore, a CrEL-free formulation of 17-AAG was prepared using amphiphilic diblock micelles of poly(ethylene oxide)-b-poly(D,L -lactide) (PEO- b -PDLLA). Dynamic light scattering revealed PEO- b -PDLLA (12:6 kDa) micelles with average sizes of 257 nm and critical micelle concentrations of 350 nM, solubilizing up to 1.5 mg/mL of 17-AAG. The area under the curve (AUC) of PEO- b -PDLLA micelles was 1.3-fold that of the standard formulation. The renal clearance (CLrenal) increased and the hepatic clearance (CLhepatic) decreased with the micelle formulation, as compared to the standard vehicle. The micellar formulation showed a 1.3-fold increase in the half-life (t1/2) of the drug in serum and 1.2-fold increase in t1/2 of urine. As expected, because it circulated longer in the blood, we also observed a 1.7-fold increase in the volume of distribution (Vd) with this micelle formulation compared to the standard formulation. Overall, the new formulation of 17-AAG in PEO- b -PDLLA (12:6 kDa) micelles resulted in a favorable 150-fold increase in solubility over 17-AAG alone, while retaining similar properties to the standard formulation. Our data indicates that the nanocarrier system can retain the pharmacokinetic disposition of 17-AAG without the need for toxic agents such as CrEL and EtOH. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:1577,1586, 2009 [source] Predictors of prognosis in patients with olfactory disturbanceANNALS OF NEUROLOGY, Issue 2 2008Brian London BA Objective Although olfaction is often compromised by such factors as head trauma, viruses, and toxic agents, the olfactory epithelium and sectors of the olfactory bulb have the potential for regeneration. This study assessed the degree to which olfactory function changes over time in patients presenting to a university-based smell and taste center with complaints of olfactory dysfunction and the influences of etiology (eg, head trauma, upper respiratory infection), sex, age, smoking behavior, degree of initial dysfunction, and other factors on such change. Methods Well-validated odor identification tests were administered to 542 patients on 2 occasions separated from one another by 3 months to 24 years. Multivariable regression and ,2 analyses assessed the influences of the variables on the longitudinal changes in olfactory test scores. Results On average, smell test scores improved modestly over time. Patient age, severity of initial olfactory loss, and the duration of dysfunction at first testing were significant predictors of the amount of the change. Etiology, sex, time between the two test administrations, and initial smoking behavior were not significant predictors. The percentage of anosmic and microsmic patients exhibiting statistically significant change in function was 56.72 and 42.86%, respectively. However, only 11.31% of anosmic and 23.31% of microsmic patients regained normal age-related function over time. Interpretation Some recovery can be expected in a significant number of patients who experience smell loss. The amount of recovery depends on the degree of initial loss, age, and the duration of loss. Etiology, per se, is not a significant determinant of prognosis, in contrast with what is commonly believed. Ann Neurol 2007 [source] Neurotoxic Effects of Three Fractions Isolated from Tityus serrulatus Scorpion VenomBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 4 2000Ana Leonor A. Nencioni Scorpion venoms contain low molecular weight basic polypeptides, neurotoxins, that are the principal toxic agents. These toxins act on ion channels, promoting a derangement that may result in an abnormal release of neurotransmitters. In the present study we investigated some of the effects of the F, H and J fractions isolated from Tityus serrulatus scorpion venom on the central nervous system of rodents. The venom was partially purified by gel filtration chromatography. The neurotoxic effect of these fractions was studied on convulsive activity after intravenous injection, and on electrographic activity and neuronal integrity of rat hippocampus when injected directly into this brain area. The results showed that intravenous injection of the F and H fractions induced convulsions, and intrahippocampal injection caused electrographic seizures in rats and neuronal damage in specific hippocampal areas. Fraction J injected intravenously reduced the general activity of mice in the open field but induced no changes when injected into the brain. These results suggest that scorpion toxins are able to act directly on the central nervous system promoting behavioural, electrographic and histological modifications. [source] Skin care for preterm and term neonatesCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 8 2009F. S. Afsar Summary Neonatal skin experiences a progressive adaptation to the extrauterine environment during which special care is needed. The immaturity of the epidermal barrier in the neonatal period may cause dry skin, vulnerability to trauma, rapid onset of microbial colonization and percutaneous drug toxicity. This article reviews the practical implications for hygiene, bathing practices, skin integrity, emollient use, infection control and exposure to percutaneous toxic agents in preterm and term infants. [source] | ||||||||||||||||