Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Permethrin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources

Pyrethroids and the striatal dopaminergic system in vivo.

1. Type I (permethrin and allethrin) or type II (cypermethrin and fenvalerate) pyrethroids caused 23-37% increases in the striatal content of the dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC). 2. Toxicity symptoms and increases in DOPAC were associated with higher brain concentrations for type I (2.6-5.8 micrograms/gm) than type II pyrethroids (0.4-0.6 micrograms/gm). 3. No specific difference in the interaction between type I and II pyrethroids and the striatal dopaminergic system were recognized.

3,4-Dihydroxyphenylacetic Acid↗

Behavioral effects of pydrin and ambush in male mice.

Male Swiss mice, 20-25 g, were utilized to assess the effects of dermal and oral administration of the pyrethroid insecticide formulations Pydrin (30% fenvalerate) and Ambush (25.6% permethrin). Animals were subjected to a conditioned taste aversion procedure using a normally preferred 0.3% saccharin solution. Subjects were allowed 30 min access to a drinking syringe containing the saccharin solution, followed immediately by the administration of the pyrethroid or control solution. Pydrin (0.3, 3.0, or 30 mg/kg orally; 60, 600, or 1800 mg/kg dermally) and Ambush (0.5, 5.0, or 50 mg/kg orally; 30, or 300 mg/kg dermally) produced significant (p less than 0.05) reductions in the percent saccharin consumed. Total fluid intake, however, was not significantly altered by any of the treatments. The effect of the insecticides on both grouped and individual activity was also assessed in 20-25 g male Swiss mice. Activity measurements were taken over the 4-hr time period immediately following the administration of the pyrethroid or control solution. Pydrin (30 mg/kg orally; 600 and 1800 mg/kg dermally) and Ambush (50 mg/kg orally; 300 mg/kg dermally) significantly (p less than 0.05) increased activity in both grouped and individually tested mice. When subjects were individually tested, significant increases were seen in non-ambulatory, but not in ambulatory activity. The results of this work indicate that administration of the commercially available preparations of Pydrin and Ambush in mice at doses that do not induce the tremor and choreoathetosis-salivation syndromes usually associated with pyrethroid insecticides may result in behavioral changes.

Administration, Cutaneous↗

Isolation and sequence analysis of a cDNA clone for a pyrethroid inducible cytochrome P450 from Helicoverpa armigera.

The complete coding sequence and parts of the 3' and 5' noncoding regions of a mRNA coding for a cytochrome P450 from Helicoverpa armigera have been obtained. The sequence is most similar to members of family CYP6, in particular that obtained from Papilio polyxenes, CYP6B1, and has been labeled CYP6B2 accordingly. The original cDNA was obtained by screening a cDNA library with an oligonucleotide specific for the amino acid sequence surrounding the cysteine residue involved in heme binding, present in the other known insect sequences. This sequence is also present in mammalian members of family CYP3. The highly conserved nature of this particular sequence suggests that this approach may allow the easy and direct identification of cDNA clones specific for members of this particular cytochrome P450 family from a wide variety of species of invertebrates and, possibly, vertebrates. The cDNA hybridizes to two major mRNAs of 2.1 and 1.8 kb in length. Induction studies indicate that the smaller mRNA is inducible by phenobarbital while the larger mRNA is inducible by the pyrethroid insecticide permethrin. Both the evolution of this particular family of cytochrome P450 genes and its potential involvement in the development of resistance to pyrethroids is discussed.

Amino Acid Sequence↗

Antiandrogenic activity of pyrethroid pesticides and their metabolite in reporter gene assay.

Many pesticides possess hormonal activity and have thus been classified as endocrine disruptors. Pyrethroids are commonly used pesticides worldwide, but little has been done to characterize their antiandrogenic activity potential. We tested three frequently encountered pyrethroids (fenvalerate, cypermethrin, permethrin) and their metabolite 3-phenoxybenzoic acid (3-PBA) for antiandrogenic and androgenic activity using a human androgen receptor (AR) mediated luciferase reporter gene assay in CV-1 African green monkey kidney cell. The assay displayed appropriate response to the known AR agonist 5alpha-dihydrotestosterone and AR antagonist nilutamide and flutamide. At 0.1mM, all the three tested pyrethroids significantly suppressed the luciferase expression. Further, their metabolite 3-PBA also showed antagonist activity. None of the test chemicals showed androgenic activity. Through the antiandrogenic pathways, exposure to certain pyrethroids may contribute to the damage of reproductive system. In conclusion, pyrethroid pesticides can act as antiandrogen in vitro, and metabolizing to 3-PBA cannot eliminate the antagonist activity. This result provides useful information for risk assessment of pyrethroid pesticides.

Androgen Antagonists↗

Effects of pyrethroid insecticides on hepatic microsomal enzymes in rats.

The effects of pyrethroid insecticides on hepatic microsomal enzymes were studied in rats. Animals were treated orally with cypermethrin (80 mg/kg), deltamethrin (15 mg/kg), and permethrin (100 mg/kg), as a solution in soyabean oil, for 1 to 20 days. The content of cytochromes P-450 and b5, activity of NADPH cytochrome P-450 reductase, glutathione S-transferase, aniline 4-hydroxylase, p-nitroanisole O-demethylase in microsomes, the activity of glutathione S-transferase, and the level of sulfhydryl groups in cytosol were determined. Also the relative liver weight was measured. Only few changes in the investigated parameters were ascertained. These changes have an irregular and transient character. On the whole, the action of pyrethroids on microsomal enzymes results in a slight induction.

Administration, Oral↗

Demodicidosis in childhood acute lymphoblastic leukemia; an opportunistic infection occurring with immunosuppression.

We report demodicidosis in 11 children with acute lymphoblastic leukemia and a mildly pruritic, erythematous papular dermatitis that developed in areas rich in sebaceous glands. Dermodex eruptions were safely and effectively treated with 5% permethrin. Proliferation of commensal parasites of the skin, Dermodex folliculorum and Dermodex brevis may be an opportunistic infection of the skin in the immunocompromised host; the expected abrogation of cell-mediated immunity secondary to lymphocyte depletion predisposes some children given chemotherapy for leukemia to mite proliferation.

Antineoplastic Combined Chemotherapy Protocols↗

Modulation of K+ transport across synaptosomes of rat brain by synthetic pyrethroids.

Potassium transport across synaptosomes was studied under the influence of two synthetic pyrethroids, (Permethrin, without the cyano group) and Cypermethrin (CPM, with the cyano group). Synaptosomes were isolated from rat brain cerebral cortex and incubated with 40 microM of PM and CPM for 15 min at 37 degrees C. K+ release was monitored by a K(+)-sensitive electrode. CPM caused more K+ release from synaptosomes compared to PM. K+ transport is regulated by Na(+)-K(+)-ATPase, K(+)-ATPase and K+ channels. To understand the mode of action, synaptosomes were preincubated with 9.5 x 10(-3) M ouabain (inhibitor of Na(+)-K(+)-ATPase), 1.7 x 10(-2) M N-ethylmaleamide (K(+)-ATPase inhibitor), and 9.5 x 10(-5) M quinine sulfate (K(+)-channel blocker) for 15 min at 37 degrees C. In the presence of ouabain and N-ethylmaleamide, PM- and CPM-induced K+ release was decreased and in the presence of quinine sulfate, there was no release of K+. Furthermore, the studies indicated that PM and CPM significantly decreased K+ uptake.

Adenosine Triphosphatases↗

Risk assessment of etofenprox (Vectron) on non-target aquatic fauna compared with other pesticides used as Simulium larvicide in a tropical environment.

Within the rotational scheme developed by the Programme to fight the resistance of Simulium damnosum to chemical larvicides, there was an operational gap at discharges between 5 and 70 m3 s(-1) for the treatment of rivers where resistance to organophosphates was present. The use of permethrin and carbosulfan was precluded because of risk of environmental impact and, Bacillus thuringiensis ser. H-14 treatments were not envisageable due to cost and logistics constraints. Among the possible complementary groups of larvicides tested, the pseudo-pyrethroids, held promise, because of a mode of action similar to that of pyrethroids, but along with a usually lower toxicity for fish. Etofenprox, one of the pseudo-pyrethroids tested, shows a global detachment of non-target insects in 24 h close to that of pyraclofos, an organo-phosphorus compound (27 against 23%). In laboratory conditions, six times the operational dose which is 0.03 mg l(-1) 10 min, is needed to cause 50% mortality of Caridina sp. (a small shrimps species) and 30 times this same dose for 95% mortality. For fish species, a safety margin of 400-800 times the operational dose is observed for Oreochromis niloticus and 200-400 times for Tilapia zillii.

Animals↗

Insect repellents: an overview.

The optimal management of arthropod bites is prevention, and many over-the-counter insect repellents are available. Since first marketed in 1956, deet has remained the most effective repellent against mosquitoes, biting fleas, gnats, and chiggers. Permethrin is applied to clothing rather than to skin, and it is a better repellent against ticks than deet. The risk of serious side effects with the use of deet is slight; nevertheless, the lowest effective concentration should be used. The current, popular repellent agents (for adults and children) and their active ingredients are discussed. In addition, the Environmental Protection Agency guidelines for the safe use of insect repellents are supplied.

Adult↗

An assessment of topical and oral prescription and over-the-counter treatments for head lice.

A plethora of head lice cases that require optimal therapeutic assessments are developing in elementary schools. Over-the-counter therapies continue to be the mainstream solution for most cases of pediculosis capitis, but the onset of resistant cases dictates a review of available treatment modalities. The increased efficacy of prescription drugs, namely topical 5% permethrin and oral ivermectin, underline the expanding role that physicians will serve in the eradication of head lice in our communities.

Administration, Oral↗

Different effects of Type I and Type II pyrethroids on erythrocyte plasma membrane properties and enzymatic activity in rats.

Pyrethroids are divided into two groups according to their chemical structures: type I pyrethroids are devoid of a cyano moiety at the alpha-position (i.e. permethrin, PERM), while type II pyrethroids have an alpha-cyano moiety (i.e. cypermethrin, CY). Type I pyrethroids cause a type I poisoning syndrome or "T syndrome", whereas type II pyrethroids induce a type II choreoathetosis syndrome, known as "CS syndrome". The aim of the present work is to compare the effect of PERM and CY on erythrocyte plasma membrane fluidity of rats, treated orally for 60 days with low and high doses of these insecticides. The different modifications induced by pyrethroids on lipid peroxidation, osmotic fragility and the antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)) were measured. The data obtained show that PERM, which proved more permeable than CY, produced an increase of fluidity and polarity in the hydrophilic-hydrophobic region of the erythrocyte bilayer even at low doses. Also at high doses, filtering through the membrane more easily, the PERM influenced more markedly the intracellular enzymatic activity, compared with CY, reducing GPx activity and increasing SOD activity. Because of its hydrophilic character, CY limits oxidative damage in the erythrocyte cytosol at high doses.

Animals↗

Toxicological and molecular characterization of pyrethroid-resistant horn flies, Haematobia irritans: identification of kdr and super-kdr point mutations.

Two pyrethroid-resistant strains of horn flies were found to be 17- and 688-fold more resistant to permethrin and 17- and 11,300-fold more resistant to cyhalothrin than a susceptible control strain. Synergism experiments with piperonyl butoxide showed that both target site insensitivity and metabolic resistance mechanisms were present in the Super Resistant strain. Using the reverse transcriptase-polymerase chain reaction (RT-PCR), a 0.9 kb fragment of the putative sodium channel gene from susceptible and resistant flies was cloned and sequenced. Two sequence variants were detected, presumably arising from alternative splicing of transcripts. The amino acid sequences deduced from the resistant and susceptible fly gene fragments were identical except for three amino acid substitutions, two of which have been associated with resistance in house flies. A leucine to phenylalanine substitution associated with knockdown resistance (kdr) was found in both resistant strains. A methionine to threonine substitution associated with super-kdr was found in the Super Resistant strain. Translation of poly(A)+ RNA followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) detected translation products whose concentrations increased in association with pyrethroid resistance. Random-amplified polymorphic DNA (RAPD)-PCR of genomic DNA with over 260 DNA oligomers yielded one resistance-associated marker, designated HF-77, which was not detected in any susceptible flies but was present in 16% of the resistant individuals.

Amino Acid Sequence↗

Bioengineering of a cellulosic fabric for insecticide delivery via grafted cyclodextrin.

beta-Cyclodextrin (beta-CD) can be easily grafted onto cellulosic textiles through covalent bonds. In such a way beta-CD empty cavities provide an efficient tool for entrapping different kinds of hydrophobic molecules on the surface of the fabric and releasing them slowly in time. The capability of cyclodextrins to include hydrophobic molecules such as fragrances, antimicrobial agents, and other chemicals can be then exploited to produce new grafted textiles with peculiar and useful performances. In this work we report the inclusion of two different products, the pyrethroid insecticide permethrin (PERM) and the insect repellent N,N-diethyl-m-toluamide (DEET), into beta-CD molecules grafted on cotton fabric. UV-vis spectrophotometry and thermal analysis confirmed the presence of the guest molecules on the fabric surface. Bioassays were carried out on two mosquito species of medical importance, Aedes aegypti and Anopheles stephensi; knock down effect and mortality were measured using standard World Health Organization (WHO) cone tests. Repellency and irritancy (blood feeding inhibition) were also measured using cage tests and a baited tunnel device. PERM-treated fabrics kept the insecticidal/irritant efficacy even for a long time after the treatment, whereas DEET activity lasted more shortly.

Aedes↗

Comparison of chemical approaches for assessing bioavailability of sediment-associated contaminants.

Two chemical approaches, Tenax extraction and matrix solid-phase microextraction (matrix-SPME), were compared to assess the bioavailability of hydrophobic contaminants from sediment. Hexachlorobiphenyl, DDE, permethrin, chlorpyrifos, and phenanthrene were individually spiked into two sediments differing in physical characteristics. Bioaccumulation was determined by exposing the oligochaete, Lumbriculus variegatus, to the spiked sediments. The rapidly desorbing fraction from Tenax extraction at 6 h and fiber concentration at 14 d from the matrix-SPME were compared for predicting bioaccumulation. Further, a comparison between laboratory-spiked and field-contaminated sediments was conducted. A regression between the rapidly desorbed sediment concentration at 6 h and the amount bioaccumulated across compounds and sediments described 94% of the variation in the data when phenanthrene was excluded. Phenanthrene was excluded because of complications due to a combination of biotransformation and rapid elimination during the sampling process. Contaminant accumulation by L. variegatus also correlated well with matrix-SPME fiber concentrations, accounting for 92% of the variation in the data, again excluding phenanthrene. Both chemical methods provided matrix- and chemical-independent estimations of bio-accumulation for hydrophobic contaminants without extensive biotransformation.

Animals↗

Recovery of synthetic pyrethroids in water samples during storage and extraction.

Monitoring for synthetic pyrethroids in surface water at the sub-parts per billion level requires reproducible sampling and analytical methods. We studied the recovery of bifenthrin, permethrin, and deltamethrin in water during storage in glass containers and extraction using solid-phase membranes. In solid-free water, the concentration of all compounds quickly decreased and then remained constant at 58-72% of the initial concentration, likely due to adsorption to the glass surface. The recovery was enhanced in runoff samples that contained suspended solids, which was attributed to the association of pesticides to the suspended solids. However, the greatest loss occurred when runoff samples were not agitated before extraction, and the loss was largely caused by the exclusion of the suspended solids from the aqueous phase. Nearly 100% extraction recoveries were obtained when C(8) or C(18) membranes were used for extracting runoff samples. Adsorption to glass surfaces and suspended solids can result in substantial underestimation of pyrethroid concentrations or biological activity and therefore should be considered when designing monitoring protocols.

Adsorption↗

Insecticide resistance spectra and resistance mechanisms in populations of Japanese encephalitis vector mosquitoes, Culex tritaeniorhynchus and Cx. gelidus, in Sri Lanka.

Culex tritaeniorhynchus Giles and Cx. gelidus Theobald (Diptera: Culicidae), both vectors of Japanese encephalitis, were collected in 1984 and 1998 from two disease endemic localities in Sri Lanka: Anaradhapura and Kandy. Using wild-caught adult mosquitoes from light traps, log dosage-probit mortality curves for insecticide bioassays were obtained for three insecticides: malathion (organophosphate), propoxur (carbamate) and permethrin (pyrethroid). LD50 values showed that, in 1998, Cx. tritaeniorhynchus was -100-fold more resistant to malathion and 10-fold more resistant to propoxur than was Cx. gelidus. This difference was attributed to Cx. tritaeniorhynchus breeding mostly in irrigated rice paddy fields, where it would have been exposed to pesticide selection pressure, whereas Cx. gelidus breeds in other types of aquatic habitats less prone to pesticide applications. Resistance in Cx. tritaeniorhynchus increased between 1984 and 1998, whereas Cx. gelidus remained predominantly susceptible. Propoxur inhibition of acetylcholinesterase (AChE) activity (the target site of organophosphates and carbamates) indicated that in 1998, frequencies of insensitive AChE-based resistance were 9% in Cx. gelidus and 2-23% in Cx. tritaeniorhynchus, whereas in 1984 this resistance mechanism was detected only in 2% of the latter species from Anaradhapura. The AChE inhibition coefficient (ki) with propoxur was 1.86+/-0.24 x 10(5) M(-)1 min(-1) for Cx. tritaeniorhynchus from Anaradhapura in 1998. Both species were tested for activity levels of detoxifying glutathione S-transferases (GSTs) and malathion-specific as well as general carboxylesterases. High activities of GSTs and carboxylesterases were detected in Cx. tritaeniorhynchus but not Cx. gelidus. Malathion-specific carboxylesterase was absent from both species. Native polyacrylamide gel electrophoresis resolved two elevated general carboxylesterases, CtrEstbeta1 and CtrEstalpha1, from Cx. tritaeniorhynchus and none from Cx. gelidus. CtrEstbeta1 was the most intensely staining band. Gel inhibition experiments showed that both elevated esterases were inhibited by organophosphates and carbamates but not by pyrethroids. The major elevated esterase CtrEstbeta1 was partially purified (15-fold) by sequential Q-Sepharose and phenyl Sepharose column chromatography. The bimolecular rate constant (ka) and the deacylation rate constant (k3) for the malaoxon/enzyme interaction were 9.9+/-1.1 x 10(3) M(-1) min(-1) and 3.5+/-0.05 x 10(-4) M(-1) min(-1), respectively, demonstrating that the role of this enzyme in organophosphorus insecticide resistance is sequestration.

Animals↗

Introducing insecticide impregnated bednets in an area of low bednet usage: an exploratory study in north-east Ghana.

To find out the acceptability of the use of insecticide impregnated bednets before launching a large-scale trial to evaluate their impact on child mortality, 96 permethrin impregnated bednets were distributed in 4 communities within the Kassena Nankana district of the Upper East Region of Ghana, where previously only 4% of the people had owned a mosquito net. The nets were readily accepted and used by the recipients. The major benefit perceived by the users was the reduction of the nuisance effect of mosquitoes and other insects. The people in the study area normally sleep on mats in either an open courtyard or a sleeping room depending on the weather but this did not deter them from using the nets. The white nets distributed for this study became dirty with use, and users thought they needed to be washed. In order to discourage this, it is recommended that dark coloured nets be used in the main intervention trial. After having used the nets for a year, the community members expressed willingness to buy the nets if they were made available after the harvest season when they had sold their crops and had enough money to pay for them. The results of this study have been used to plan and conduct a large intervention trial.

Bedding and Linens↗

Operational aspects of bednet impregnation for community-based malaria control in Nicaragua, Ecuador, Peru and Colombia.

Community intervention projects with pyrethroid (permethrin and lambdacyhalothrin) impregnated bednets and an accompanying community education programme were carried out in 6 malaria endemic areas on the Pacific coast of Nicaragua, Ecuador, Peru and Colombia as well as in the Peruvian Amazon basin. In this paper the operational aspects are analysed: bednet coverage, results of promotional activities for increased bednet use, the sale of low-cost bednets, techniques and difficulties with impregnation, acceptance of the programme (including washing of impregnated nets), side-effects, residual concentrations of the chemical in the nets, costs of the impregnation programme and insecticide resistance of the malaria vectors. We found that the local manufacture of bednets and their sale through village health workers, even in communities with low cash income, is a viable way of increasing bednet coverage; the impregnation of bednets is well accepted if villagers perceive a direct benefit; pretesting of the soaking capacity of different net materials should be done at central level; the instructions for the impregnation procedures of different net materials (cotton and synthetic) should be simple and unambiguous; very cheap thin net materials should be avoided, particularly in the case of lambdacyhalothrin impregnation; educational methods and/or promotion of dark-colour nets should be further tested in order to decrease the washing frequency of bednets at household level; in areas with early-biting mosquitoes further studies on the protective efficacy of bednets are necessary; careful monitoring of side-effects, particularly those of last-generation pyrethroids, is necessary; and the community-based impregnation programme is a powerful tool for strengthening community involvement in health actions.

Bedding and Linens↗