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At least 1,405 records · Page 78Linked to original sources
PubMed1987

Pyrethroid insecticides and radioligand displacement from the GABA receptor chloride ionophore complex.

Radioligand binding displacement studies were conducted to determine the effects of Type I and II pyrethroids on [3H]flunitrazepam (FLU), [3H]muscimol (MUS), and [35S]t-butylbicyclophosphorothionate (TBPS) binding. Competition experiments with [3H]FLU and [3H]MUS indicate a lack of competition for binding by the pyrethroids. Type I pyrethroids failed to compete for the binding of [35S]TBPS at concentrations as high as 50 microM. Type II pyrethroids inhibited [35S]TBPS binding to rat brain synaptosomes with Ki values ranging from 5-10 microM. The data presented here suggest that the interaction of Type II pyrethroids with the gamma-aminobutyric acid (GABA) receptor-ionophore complex is restricted to a site near the TBPS/picrotoxinin binding site.

Animals↗
PubMed2004

Direct high-performance liquid chromatographic method for enantioselective and diastereoselective determination of selected pyrethroic acids.

This study reports on the direct HPLC stereoisomer separation of selected pyrethroic acids employing commercial cinchona alkaloid derived chiral stationary phases (CSPs). cis/trans-Chrysanthemic acid (cis/trans-CA), cis/trans-chrysanthemum dicarboxylic acid (cis/trans-CDCA), cis/trans-permethrinic acid (cis/trans-PA), and fenvaleric acid (FA) were resolved into the individual stereoisomers, i.e. enantiomers and diastereomers as well. To achieve satisfactory baseline separation an optimisation of the variables of the chromatographic method including chemical structure of the cinchona carbamate CSP, mobile phase composition, and flow rate was required. All four stereoisomers of PA were successfully separated in a single run (alphacis = 1.20, alphatrans = 1.26, critical Rs = 1.65) with an acetonitrile (ACN)-based polar-organic eluent. The complete baseline resolution of all CA stereoisomers succeeded in polar-organic (alphacis = 1.20, alphatrans = 1.35, critical Rs = 3.03) as well as in acetonitrile-based reversed-phase media (alphacis = 1.24, alphatrans = 1.22, critical Rs = 2.73). The latter elution mode was also found to be suitable for the enantio- as well as diastereoselective resolution of CDCA (alphacis = 1.09, alphatrans = 1.50, critical Rs = 1.43), which is to the best of our knowledge the first reported enantiomer separation of this analyte. The enantiomers of FA could be baseline separated employing also reversed-phase mode (alpha = 1.16, Rs = 2.91). These separation methods may be applied for quality control processes in the production of stereoisomerically pure insecticides as well as stereoselective toxicokinetic studies, as CDCA, PA, and FA are suitable biomarkers for monitoring human pyrethroid burden.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Scabies, pediculosis, bedbugs, and stinkbugs: uncommon presentations.

Parasitic agents determine some of the most common skin disorders. Although well known, they could present different manifestations or be modified by individual or external factors that make their diagnosis or treatment difficult. This review will discuss some of the most prevalent parasitic infections, scabies, and pediculosis and also mention reactions determined by contact with certain insects that, although rarely found, could induce important skin reactions.

Adolescent↗
PubMed2006

Pyrethroid-resistant diamondback moth expresses alternatively spliced sodium channel transcripts with and without T929I mutation.

This study revealed two distinct alternatively spliced exons, A1 and A2, encoding part of the domain IIS4-IIS5 of the para-sodium channel gene in the diamondback moth (DBM). Exons A1 and A2, respectively, revealed 79% and 91% identity at the nucleotide and amino acid levels. Both alternative exons included the T929I site, which has been associated with pyrethroid resistance in DBM. In the pyrethroid-resistant strain, susceptible (Thr) and resistant (Ile) amino acids were encoded at the T929I site in exons A1 and A2, respectively, but in the pyrethroid-susceptible strain, only Thr was encoded at the site in both exons. The transcripts containing exon A1 were expressed constitutively in all developmental stages. The transcripts containing exon A2 were also detected in all developmental stages, but the levels were significantly lower in the 3rd and 4th instar larvae. Tissue-specific data from the 4th instar larvae and adults showed that the expression of transcripts containing exon A2 was higher in heads than in bodies. These findings suggest that alternative splicing of the para-sodium channel gene might produce distinct channels with different sensitivities to pyrethroids, possibly in a tissue-specific manner.

Alternative Splicing↗
PubMed2006

Systematic review of rosacea treatments.

BACKGROUND: Rosacea is a common chronic skin and ocular condition. It is unclear which treatments are most effective. We have conducted a Cochrane review of rosacea therapies. This article is a distillation of that work. OBJECTIVE: We sought to assess the evidence for the efficacy and safety of rosacea therapies. METHODS: Multiple databases were systematically searched. Randomized controlled trials in people with moderate to severe rosacea were included. Study selection, assessment of methodologic quality, data extraction, and analysis were carried out by two independent researchers. RESULTS: In all, 29 studies met inclusion criteria. Topical metronidazole is more effective than placebo (odds ratio 5.96, 95% confidence interval 2.95-12.06). Azelaic acid is more effective than placebo (odds ratio 2.45, 95% confidence interval 1.82-3.28). Firm conclusions could not be drawn about other therapies. LIMITATIONS: The quality of the studies was generally poor. CONCLUSIONS: There is evidence that topical metronidazole and azelaic acid are effective. There is some evidence that oral metronidazole and tetracycline are effective. More well-designed, randomized controlled trials are required to provide better evidence of the efficacy and safety of other rosacea therapies.

Administration, Cutaneous↗
PubMed1997

Accuracy and reproducibility of calibrations on the skin using the fives fluorescence monitor.

Dermal contamination from products such as pesticide formulations may be measured by adding a fluorescent dye as a tracer, and photographing the glow of the dye on the skin under ultraviolet light. The Fluorescence Interactive Video Exposure System (FIVES) fluorescence monitor, developed at the Health and Safety Laboratory, uses calibrations of intensity of glow against surface concentration of dye which are affected by the natural fluorescence of the skin and by skin hue. Calibrations of two dye/product mixtures upon the skin of several volunteers showed that a simple multiplicative correction procedure aligned all the responses to one calibration curve for each mixture. The palms of the hands were an exception, because their natural fluorescence was much higher than other areas of skin, and the relation no longer held. A further correction factor aligned their responses with the rest. The calibration data were fitted best by log-log polynomials, although linear polynomials were acceptable. Using this new procedure, the FIVES monitor could estimate dermal contamination to within +/- 70% of known applied doses. Upon exposure to light, the dyes on the skin were found to fade by 20% in 1/2 h, but no further in 1 h. The procedure and calibrations developed here were used in an experiment to estimate the likely dermal exposures of amateur or occasional biocide users, painting ready-to-use wood preservative fluids onto a trellis fence outdoors.

Calibration↗
PubMedDate not supplied

Evidence for a mass community effect of insecticide-treated bednets on the incidence of malaria on the Kenyan coast.

The use of insecticide-treated bednets (ITBNs) has been shown to be effective in reducing mortality and morbidity from malaria. However, there is mixed evidence as to whether or not community-wide use of ITBNs engenders a 'mass effect', such that those not sleeping under bednets are offered protection from widespread ITBN use in the area in which they live. We have analysed data collected in Kilifi, Kenya, from a cohort of children followed from birth to investigate how the degree of net usage in the locality of a child affects the risk of developing malaria. This effect was explored using a Cox proportional hazards model. For those not using ITBNs, we found that an increasing level of ITBN usage within the area surrounding each child was associated with a decreasing risk of developing malaria, thus providing evidence in support of a mass community effect. The size and significance of this effect were found to decrease as non-overlapping areas of increasing distance away from a child's home were considered. The effect was significant for areas at distances of up to 1.5 km away from each child.

Bedding and Linens↗
PubMedDate not supplied

Insecticide-treated materials, mosquito adaptation and mass effect: entomological observations after five years of vector control in Burkina Faso.

Insecticide-treated bednets and curtains have been shown to be successful in reducing malaria transmission and child mortality in Africa over periods of up to 2 years. A major concern relating to this approach is that, in time, it will be compromised by the selection of mosquito genotypes that are resistant at the biochemical or behavioural level. We report entomological data from a large area in Burkina Faso where insecticide-treated curtains have been in use for up to 5 years. Longitudinal indoor and outdoor CDC light-trap catches were performed in 4 sentinel villages. In addition cross-sectional surveys using indoor spray catches and outdoor CDC light-trap catches were performed each September in a larger number of villages, including 8 located outside the intervention area. We found no evidence of the selection of mosquito phenotypes that might compromise the intervention. Indoor and outdoor vector densities remained very low after 5 years of intervention, both compared with pre-intervention levels and with concurrent levels outside the intervention area. We found no evidence of a switch to outdoor rather than indoor biting. The proportion of blood meals taken on humans may have decreased but our data are inconclusive on this point. We observed higher vector densities and sporozoite rates at the periphery of the intervention zone than at the centre, which may reflect re-invasion of peripheral villages by mosquitoes from outside the intervention area. In 'real life' programmes, with perhaps patchy, less than optimal coverage, the protection against malaria transmission provided to individuals using insecticide-treated materials may be less than that achieved in the randomized controlled trials which demonstrated an impact of insecticide-treated materials on child mortality.

Animals↗
PubMedDate not supplied

The impact of a national impregnated bed net programme on the outcome of pregnancy in primigravidae in The Gambia.

In 1992, the Gambian national impregnated bed net programme (NIBP) introduced insecticide treatment of bed nets into half of the primary health care villages in The Gambia. One component of the evaluation of this programme was the determination of whether it had any impact on the outcome of pregnancy in primigravidae. From February 1992, 651 primigravidae were recruited into the study. Less than 50% of them used an insecticide-treated bednet. During the rainy season the prevalence of Plasmodium falciparum among primigravidae was lower, fewer babies were classified as premature, and the mean birth weight was higher in villages where treated bed nets were used than in control villages. Therefore, during the rainy season, despite the low use of insecticide-treated bed nets by Gambian primigravidae, the NIBP had some impact on the outcome of pregnancy, particularly on the percentage of premature babies, and this was probably due to the decreased risk of malaria infection achieved during this period.

Adolescent↗
PubMedDate not supplied

C-reactive protein and haptoglobin in the evaluation of a community-based malaria control programme.

When cross-sectional surveys are used to evaluate malaria intervention programmes in the community, the prevalence of morbidity is difficult to assess because of the fluctuating nature of malarial fever. We have therefore investigated the impact of bed net usage on 2 surrogate markers of malarial morbidity: (i) elevated C-reactive protein (CRP) (> 8 mg/L) plus detectable parasitaemia, as an indicator of malaria-induced acute-phase response; and (ii) reduced haptoglobin levels (< 180 mg/L), which in this population indicates malaria-induced intravascular haemolysis. Among 1505 Gambian children 1-5 years old, examined on a single occasion at the end of the malarial transmission season, 5% had parasitaemia plus fever, while 24% had parasitaemia plus elevated CRP, and 35% had low haptoglobin. The proportion of children who had parasitaemia plus elevated CRP was significantly lower among those who had slept under insecticide-treated bed nets than among those who did not use a bed net (16% vs. 34%, P < 0.003), and the proportion with low haptoglobin differed similarly (24% vs. 49%, P < 0.003). Use of an untreated bed net had a weaker effect on both indices (22% had parasitaemia plus elevated CRP, 34% had low haptoglobin). CRP and haptoglobin are simple and inexpensive to measure in large numbers of people, and these results suggest that they could be useful for the assessment of malaria intervention programmes.

Bedding and Linens↗