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At least 649 records · Page 36Linked to original sources
PubMed2001

Peripheral cholinesterase inhibition by occupational chlorpyrifos exposure in Australian termiticide applicators.

Occupational exposure to organophosphorus insecticides (OPs), such as chlorpyrifos, may be monitored by the measurement of the activity of peripheral cholinesterase (ChE) enzymes, including erythrocyte acetylcholinesterase (EAChE) and serum cholinesterase (SChE). Lymphocyte neuropathy target esterase (NTE) is thought to have potential as a predictor of organophosphate-induced delayed neuropathy (OPIDN). This paper describes work performed in 39 Australian pest control operators (PCOs) exposed to a termiticide containing chlorpyrifos, and 34 unexposed control subjects. EAChE activities in PCOs did not differ from those of unexposed control workers. Mean NTE activity was slightly higher in PCOs than in controls and mean SChE was 52% of control activity. These results indicate that exposure of Australian PCOs to termiticides containing chlorpyrifos may be monitored using SChE but not EAChE or NTE, and that workers in this industry have sufficiently high OP exposure to significantly depress SChE activity. SChE inhibition of 70-80% may be associated with symptoms. Although no current symptoms were reported to be associated with occupational OP exposure, these workers may be at increased risk of acute effects following inadvertent spills or self-contamination due to their background level of exposure to OPs. While it is preferable to compare ChE enzyme activities between pre- and post-exposure periods to evaluate OP-related effects in individuals, in some cases there is an absence of pre-exposure data. The results of this study suggest that a screening value for SChE of 550 nmol/min/ml in a single blood sample may be useful to identify potentially OP-exposed individuals in the Australian population. Australian control subjects were similar with respect to EAChE, but displayed activities of NTE and SChE approximately 50 and 23% lower than an unexposed UK reference group. While these comparisons are presently speculative, they suggest that there may be differences in SChE and NTE activities in control populations of the two countries. The routine treatment of Australian homes with termiticides containing OPs, or differences in the availability and use of domestic OP-containing insecticides may explain these population differences. Further work is required to examine whether these differences are real, and if so their likely cause.

Australia↗
PubMed2000

Evaluation of carcinogenic and co-carcinogenic potential Quinalphos in mouse skin.

Quinalphos [O,O-diethyl-O-quinoxalinyl-phosphorothidate] is an organophosphorus pesticide with tremendous utility in mixed pest control due to its insecticidal and acaricidal properties. Apart from its pesticidal property, Quinalphos is known to induce various toxic effects in nontarget species and experimental animals. No studies have been conducted to evaluate the carcinogenic/co-carcinogenic hazards associated with Quinalphos exposure. In the present set of investigations, the tumorigenic potential of Quinalphos has been evaluated following topical exposure in Swiss albino mice. Long-term animal bioassays conducted for the evaluation of complete carcinogenic, tumour-initiating and tumour-promoting potential of Quinalphos revealed that it has only tumour-initiating potential at a dose of 10 mg/kg body weight (b.wt.), in the two-stage mouse skin model of carcinogenesis. Quinalphos exposure failed to produce neoplasia when tested for complete carcinogenic activity at all three tested dose levels or tumour promoting activity.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1997

Novel vaccines for ectoparasites.

Novel vaccines against ectoparasites have the potential to be cost-effective new technology for pest control that avoids some of the real and perceived problems with insecticide and acaricide usage. Nevertheless, their development is in its infancy. A vaccine against the cattle tick Boophilus microplus, the world's first vaccine against an ectoparasite, is in field use in Australia. Considerable effort had gone into the development of a vaccine against the sheep blowfly Lucilia cuprina, while other vaccines are at an earlier stage of development. The identification of critical antigens and their production as effective recombinant proteins remains the greatest hurdle. Characteristics of the few known antigens and the mode of action of the protective immune response are discussed. Development of further vaccines will depend on recognition of likely antigenic targets. The efficacy of such vaccines will depend on the characteristics of the target species, in particular its digestive biology and the way in which the novel vaccine impacts on the parasite population.

Animals↗
PubMed1999

Consideration of individual susceptibility in adverse pesticide effects.

The modern environmental awareness leads to the realisation that the human metabolism is stressed by a huge number of chemical substances. Generally, these background exposures, consisting predominantly from natural and partly from industrial as well as life style sources, are tolerated without any adverse effects. Pesticides are chemicals intentionally introduced to the environment and have become necessities in modern agriculture as well as in indoor pest control. Their residues, therefore, is attracting more and more concern. For the majority of pesticides neither occupational nor environmental medical risk evaluations are so far available. Therefore, at the moment the occupational as well as the environmental supported preventive concept may only be achieved, if binding instructions upon experience and guide values are developed for the assessment of the individual risk of handling pesticides. In the occupational and environmental pesticide prophylaxis the ubiquitous background exposure levels in consideration with individual susceptibility factors should be recommended as provisional biological tolerance guide values. The suitability of this guide values concept for pesticides is demonstrated by determining the background exposure and the biomarkers of susceptibility of 250 unexposed persons as well as of more than 1200 occupationally exposed persons. As a result, a significant dependence of their health fidelity from the background exposure profile impressed on the individual polymorphism of the key enzymes was observed. Especially, the cumulative adducts of electrophilic substances and their metabolites with macromolecules like HSA and Hb turned out to be sensitive markers for the capacity of the individual metabolic rate. For alkylating and arylating pesticides the observed interindividual susceptibility to their adverse effects depends on the variability of the individual 'toxifying' and 'detoxifying' metabolic rates. Until scientific evaluation of official biological tolerance values for pesticides is carried out, it is advisable for risk prophylaxis to orientate the assessment of any individual tolerable stress and strain from pesticides to the synergism between background exposure, life style factors and biomarkers of specific susceptibility. They may be examined by a monitoring of conjugates and polymorphism marked by the individual metabolic rate. The monitoring and surveillance of pesticide exposures is mainly introduced by the recommendation of tolerable biological values from the reference value concept. This concept is an essential contribution to an objective risk discussion with regard to individual stress and strain profiles in environmental exposure scenarios.

Diuron↗
PubMed1997

Determination of metabolites of pyrethroids in human urine using solid-phase extraction and gas chromatography-mass spectrometry.

The described method permits the determination of the five most important metabolites of the pyrethroids permethrin, cypermethrin, deltamethrin, lambda-cyhalothrin, fenvalerate, phenothrin and beta-cyfluthrin in human urine in one run. The major urinary metabolites of these substances are cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cis-Cl2CA), trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (trans-Cl2CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (Br2CA), fluoro-3-phenoxybenzoic acid (F-PBA) and 3-phenoxybenzoic acid (3-PBA). After acidic hydrolysis to release the conjugated carboxylic acid metabolites, the analytes were separated from the matrix by means of solid-phase extraction using a reversed-phase column. The components of the eluate were converted to their methyl esters and extracted in hexane. Separation and quantitative analysis of the pyrethroid metabolites was carried out by capillary gas chromatography and mass selective detection. 2-Phenoxybenzoic acid served as an internal standard. The detection limits lay between 0.3 and 0.5 microg per litre urine. The relative standard deviations of the within-series imprecision were between 1% and 6%. The relative recovery rates ranged between 90% and 98%. Using this method we determined the elimination of pyrethroid metabolites in 24-h urine samples from eight pest controllers after indoor application of permethrin. The detected concentrations ranged from 1 to 70 microg g(-1) creatinine.

Air Pollutants, Occupational↗
PubMed1998

Determination of endosulfan and its metabolites in human urine using gas chromatography-tandem mass spectrometry.

A method was developed for determining the occupational exposure to endosulfan and its main metabolites (endosulfanether, -lactone and -sulfate) in human urine using dieldrin as an internal standard. Solid phase extraction (SPE) and gas chromatography-tandem mass spectrometry (GC-MS-MS) have been used due to their high sensitivity and selectivity in avoiding most matrix interferences. The recovery efficiencies of the tested compounds yielded more than 89.2% at the fortification level of 10 ng ml(-1) in urine and their relative standard deviations were between 9.1 and 12.8%. The detection limit of each compound ranged between 6 and 18 pg ml(-1). Urine samples from nine pest control operators were analysed and total endosulfan concentrations between 94 and 2038 pg ml(-1) were found.

Calibration↗
PubMed1999

Gas chromatographic method with mass-selective detection for the determination of 2-isopropoxyphenol in human urine.

Human metabolism of the insecticide propoxur yields 2-isopropoxyphenol (IPP) which is excreted conjugated in urine. In this publication a sensitive and selective analytical method is described which permits the determination of IPP as a suitable parameter for biomonitoring. The clean-up of the hydrolysed urine samples consisted of steam distillation and solid-phase extraction using a reversed-phase column. IPP and the internal standard 2-ethoxyphenol were converted to their pentafluorobenzyl ethers. Excess of the derivatisation reagent was removed using deactivated silica gel. Separation and quantitative analysis was carried out by capillary gas chromatography and mass selective detection. Coefficients of variation were below 5% for concentrations from 6 to 300 microg/l. The detection limit was 0.5 microg/l. The method was checked by analysing six urine samples from pest controllers after indoor application of propoxur. The IPP concentrations ranged from 45 to 306 microg/g creatinine. IPP was not detected in urine specimens from 10 non-exposed persons. The sensitivity of the developed method permits the detection of latent exposure to propoxur.

Gas Chromatography-Mass Spectrometry↗
PubMed2000

Evaluation of some Moroccan medicinal plant extracts for larvicidal activity.

The larvicidal properties of 16 extracts of four Moroccan medicinal plants: Calotropis procera (Wild.), Cotula cinerea (L.), Solanum sodomaeum (L.) and Solanum elaeagnifolium (CAV.) were tested against Anopheles labranchiae mosquito larvae. Among the extracts tested, nine exhibited high larvicidal activity with LC(50) (24 h) ranging from 28 to 325 ppm.

Animals↗
PubMed1998

A novel class of mosquitocidal delta-endotoxin, Cry19B, encoded by a Bacillus thuringiensis serovar higo gene.

Partially digested HincII fragments of DNA from a mosquitocidal strain of Bacillus thuringiensis serovar higo were cloned into pBluescript II SK(+) and propagated in Escherichia coli. Recombinant cells were screened immunologically for the production of parasporal inclusion antigens. One E. coli clone harboring a recombinant plasmid exhibited larvicidal activity to Culex pipiens molestus, but not to Anopheles stephensi. Hybridization experiments revealed that the gene of the toxin protein is located on a 110 kb plasmid of B. thuringiensis serovar higo. Sequence analysis detected an open reading frame of 2046 nucleotides encoding a polypeptide of 682 amino acid residues with a predicted molecular weight of 78,467. The gene encoded five block regions commonly conserved in the insecticidal protein genes of B. thuringiensis. Amino acid sequence of the 78 kDa protein shared 49% identity and 56% similarity with that of the Cry19A protein from B. thuringiensis serovar jegathesan. A new class of delta-endotoxin protein, designated Cry19B, was established on the basis of this protein.

Amino Acid Sequence↗
PubMed2002

A new second-derivative spectrophotometric method for the determination of permethrin in shampoo.

Permethrin, a highly effective insecticide agent, has been widely used for the pest control in agriculture and the treatment of lice in human. A fast and reliable method for the determination of permethrin was highly desirable to support formulation screening and quality control. A second-derivative UV spectroscopic method was developed for the determination of permethrin in the shampoo dosage form after extraction. The second-derivative spectrum recorded between 250 and 310 nm, and a zero-crossing technique for second-derivative measurement at 279 nm was selected. It is found that the selectivity and sensitivity of the method to be in desirable range. In comparison with the direct UV method, second-derivative UV spectroscopy eliminates the interference from UV absorbing excipients. This method is also fast and economical in comparison with the more time-consuming GC method regularly used for formulation screening and quality control and can be used routinely by any laboratory possessing a spectrophotometer with a derivative accessory. The linear concentration ranges were 0.25-1.5 ppm (D2=0.00042Conc.+0.0018, r=0.9972, n=10). Between day of CV%</=2.81, within day of CV%</=3.50, and an analytical recovery close to 95-100% shows the suitability of the method for determination in quality control.

Hair Preparations↗
PubMed2003

Challenges for mass production of nematodes in submerged culture.

Nematodes of Steinernema and Heterorhabditis genera are used as agents in insect biocontrol programs. They are associated with specific bacteria which are also involved in the mechanism of pathogenicity and which are consumed by nematodes as living food. S. feltiae has various developmental stages in its life cycle, including four juvenile stages, adults and the free living form. During mating, males coil themselves around the female, which is around 1 cm long. Successful commercialization of nematode-bacteria biocontrol products depends on the ability to produce sufficient quantities of these products at competitive prices for a full pest control program. This could be feasible if high cell density submerged cultures are designed and implemented; however, major problems related to nematodes mass production in a bioreactor remain unsolved due to the lack of knowledge about the physiological aspects of the nematode, bacteria and nematode-bacteria association, interaction between the three phases present in the bioreactor (liquid, gas, nematodes-bacteria), possibility of mating under hydrodynamic stress conditions, etc. We have found that the two most important engineering aspects to take into account the mass propagation of nematodes are oxygen transfer rate and hydrodynamics to allow mating and to avoid mechanical damage of juveniles in stage 2. This article focuses on several aspects related to the fermentation system such as kinetics of growth, shear stress, hydrodynamics fields in the bioreactor and oxygen demand. Also, results published by other groups, together with those of our own, will be discussed in relation to the main challenges found during the fermentation process.

Animals↗
PubMed1989

Organophosphorus and carbamate insecticide poisoning in large animals.

Organophosphorus and carbamate insecticides are used commonly in agriculture to control pests of crops and animals. These compounds are toxic and livestock poisoning has occurred from mistaken addition of unused insecticide to feeds and animal access to improperly disposed of materials or "empty" containers. The morbidity rate approximates a third of animals exposed and about half of those affected die. Organophosphorus and carbamate insecticides generate their toxic effects by bonding to and inhibiting ChE enzymes (most importantly, AChE), which are responsible for breaking down the neurotransmitter ACh. The accumulation of ACh results in uninhibited impulse transmission at the cholinergic endings, including autonomic preganglionic junctions, certain neurons in the central nervous system, and motor nerves to the skeletal muscles. This eventually leads to fatigue of end organs; death usually is a result of respiratory failure. The "delayed neuropathy syndrome" is caused by some OP insecticides, but the pathophysiology of this syndrome does not involve the inhibition of ChE and accumulation of neurotransmitter. Over 100 anticholinesterase insecticides are in use. Variations in toxicity exist among these compounds, but larger diversities exist in the likelihood of poisoning because of differences in formulations, solvents, and conditions of use. Young animals usually are more sensitive than adults. Some of these agents are among the most toxic of manmade chemicals. These insecticides generally do not accumulate in tissues. The "chronic" effects depend on accrued physiological changes from frequent exposure to nonlethal doses. Clinical signs occur within minutes to a few hours and include the muscarinic signs of salivation, excessive lacrimation, frequent urination, and diarrhea. Concurrent nicotinic effects include muscular tremors followed by weakness and paralysis. Topical exposure results in similar poisoning but the onset of clinical signs may be delayed. Certain pour-on insecticides may cause a delayed (more than a week) syndrome in some breeds. Diagnosis of OP or carbamate insecticide poisoning is made by (1) interpretation of clinical signs and history that are consistent with this poisoning, (2) detection of the chemical compound in stomach or rumen contents and tissues, and (3) demonstration of the adverse biological effect, ChE inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2002

A high-affinity octopamine transporter cloned from the central nervous system of cabbage looper Trichoplusia ni.

A cDNA encoding a high-affinity Na(+)/anion(-)-dependent octopamine transporter (OAT) was isolated via an RT-PCR-based approach from caterpillars of the cabbage looper, Trichoplusia ni. The deduced amino acid sequence of the OAT cDNA predicts a 670 amino acid protein bearing strong homology to previously cloned monoamine transporters. The expression pattern of OAT mRNA in the central nervous system revealed by in situ hybridization closely resembles that of OA-ergic neurons identified by the presence of mRNA for tyramine beta-hydroxylase, a marker enzyme for OA-ergic neurons in invertebrates. In vitro, insect cells infected with OAT-expressing baculovirus accumulated both (3)H-OA and (3)H-dopamine with saturation kinetics typical of carrier-mediated processes. (3)H-dopamine uptake by OAT was most inhibited by tyramine, OA, dopamine and the tricyclic antidepressants desipramine and imipramine. Substitution studies for Na(+) and Cl(-) indicate that OAT has a strong requirement for Na(+) and a less stringent requirement for Cl(-). The pharmacological profile of OAT is distinct from those of other cloned monoamine transporters and makes OAT a potential target for neuro-active pest control agents.

Adrenergic alpha-Agonists↗
PubMed2002

Re-engineering the sterile insect technique.

The mass release of sterile insects (the Sterile Insect Technique, SIT) is a highly effective area-wide method of pest control with a low environmental impact. SIT relies on the sterilization by irradiation of large numbers of insects. This has unavoidable costs in terms of the fitness of the irradiated insects and the financial requirements of constructing and operating the radiation facility. In many cases it is considered important to release only males, but large-scale sex-separation is also problematic. I have proposed that both of these difficulties can be overcome by using engineered strains of insects carrying a dominant, repressible, lethal gene or genetic system. As a proof of principle, my group and others have constructed strains of Drosophila melanogaster with the required genetic properties.

Animals↗
PubMed1998

Engineering disease and pest resistance in plants.

Improvements in transformation techniques and the isolation of many genes whose transcripts or protein products either have antimicrobial or insecticidal activity or are involved in the synthesis of products with such activities have provided valuable tools for engineering resistance in plants. Future exploitation of this technology should provide an environmentally friendly alternative to traditional disease and pest control measures.

Anti-Infective Agents↗
PubMed2004

Biological control of fire ants: an update on new techniques.

OBJECTIVE: To review the present understanding of biological control methods for imported fire ants (IFAs). DATA SOURCES: We searched MEDLINE, Biological Abstracts, and the US Department of Agriculture Formis Ant Literature database. STUDY SELECTION: All articles published in the last 10 years on biological control of fire ants were selected. RESULTS: The decapitating flies Pseudacteon tricuspis, Pseudacteon curvatus, and Pseudacteon litoralis have been successfully released in the United States. The continued releases of multiple species of decapitating flies will expand the area of impact, applying greater pressure on IFA populations throughout the southern United States. The microsporidium Thelohania solenopsae causes the slow demise of a fire ant colony. The advantages of T. solenopsae as a biological control agent include debilitation of queens, specificity for IFAs, self-sustaining infections, and lower relative tolerance to chemical pesticides. Solenopsis daguerrei has also been shown to have detrimental effects on IFA colony growth, the number of sexual reproductives produced, and the number of host queens in multiple queen colonies; however, this parasite is difficult to rear in the laboratory and to introduce into IFA colonies. CONCLUSIONS: It is unlikely that IFAs can be completely eradicated from the United States. However, technology using chemicals and/or natural control agents could eventually maintain populations at low levels if an integrated approach is used for control.

Animals↗
PubMed1998

Home care concerns for the normal newborn.

Four of the most common problems encountered with newborns in the home include feeding difficulties, jaundice, gastrointestinal problems, and inconsolable crying. This article suggests assessment measures and intervention strategies to deal with these problems and evaluate the home environment for safety. This article also includes suggestions to promote safe infant feeding, bathing, sleeping arrangements, car safety seats, firearm and poison storage, fall prevention, concerns about pets, pest control, heating and cooling, and a nonsmoking environment.

Community Health Nursing↗
PubMed2001

Multiple responses in gene expression in fish treated with estrogen.

During the last decade there has been a significant body of research conducted on environmental estrogens. These include industrial, agricultural and pest-control chemicals that bind to the estrogen receptor and induce biological changes during development or reproduction. Most of these changes are probably due to modified gene expression, since estrogen receptors function at this level. We have mapped qualitative gene expression responses (by differential display reverse transcriptase polymerase chain reaction, DD) in adult male sheepshead minnows (Cyprinidon variegatus) receiving high dose injections (5 mg/kg), or constant flow-through aquatic exposures to environmentally relevant concentrations (100 ng/l) of estradiol-17beta, and found them nearly identical. We have observed both up-regulation and down-regulation of transcripts, which fit into known responses to estradiol. Among the genes up-regulated are vitellogenin and several vitelline envelope proteins indicating that genes for proteins involved in egg development and maturation are susceptible to environmental estrogen exposure. While physiological changes caused by estradiol treatment are not totally explained by changes at the mRNA level, those changes can nevertheless be used as fingerprints to characterize an in vivo estrogenic response.

Animals↗