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PubMed1986

Personal antimosquito measures plus proguanil for malaria prophylaxis in southern Malaysia.

During the early months of 1985 and 1986, 408 non-immune British soldiers undertook training in the jungles north of Kota Tinggi, in southern Malaysia. In this geographical location, where malaria transmission is now light, a combination of strict personal antimosquito measures plus proguanil 200 mg daily produced effective, safe protection, with only a single case of vivax malaria occurring. Given the limited malaria risk, however, the results of this study should be extrapolated only with caution to other areas of Malaysia.

Clothing↗
PubMed1988

Malaria prophylaxis amongst British residents of Lilongwe and Kasungu districts, Malawi.

Questionnaires on various aspects of malaria prophylaxis were distributed to all British residents (adults and children) of Lilongwe and Kasungu districts, Malawi, and were completed and returned by 293 (response rate 89%). Almost all residents used some measures to reduce mosquito contact, and 96% used chemoprophylaxis. Eight different chemoprophylactic regimens were used. Proguanil, alone or with chloroquine, was the most popular agent despite being associated with mouth ulcers in 25% of residents. Residents on this regimen had in general obtained their advice from a British source, and 75% considered they were adequately informed on the subject. This regimen was the most effective in preventing malaria attacks in the previous 12 months, even though over half those on proguanil alone were taking an inadequate dose. Residents on other chemoprophylactic regimens in general obtained their advice elsewhere, considered they were inadequately informed, and had a higher incidence of malaria. Whatever the regimen, 27% of adult residents would discontinue prophylaxis prematurely on return to the United Kingdom. Results suggest that more needs to be done to provide regular, precise and up-to-date information on malaria prophylaxis to British residents in malaria endemic areas.

Adolescent↗
PubMed1994

Detection of electrophoretically separated protease inhibitors using X-ray film.

Pigeon-pea seed extracts have been analyzed for the protease inhibitors using a new, sensitive and simple method for visualization of electrophoretically separated protease inhibitors. The visualization involves equilibrating the gel successively in the protease assay buffer, protease solution, rinsing the gel in protease assay buffer, and exposing it to an exposed, undeveloped X-ray film. Gelatin on the film in places corresponding to the inhibitor bands remains unhydrolyzed. By this method the pigeon-pea seed extract was found to contain nine trypsin and at least seven chymotrypsin inhibitors but no papain or bromelain inhibitors.

Cost Savings↗
PubMed1994

Induction of chromosome aberrations and micronuclei in pulmonary alveolar macrophages of rats following inhalation of mosquito coil smoke.

The genotoxic potential of inhalation of mosquito coil (MC) smoke was evaluated by using metaphase chromosome aberration and micronucleus assays in pulmonary alveolar macrophages (PAMs) of rats following short-term as well as long-term whole body intermittent exposure. For short-term exposure, the animals were exposed for 15 min/h, 8 h/day to smoke collected for 1, 5 or 10 min, and they were killed 16 or 24 h after the final exposure. For long-term exposure, they were exposed for 15 min/h, 8 h/day, 7 days/week to smoke collected for 10 min and then they were killed 24 h after the final exposure. Each time before exposure, fresh smoke was collected by burning a mosquito coil. Pulmonary lavage was collected, and conventional flame-drying preparation was done for metaphase chromosome analysis and micronuclei (MN) were analyzed from smear preparations. Significantly higher frequencies of chromosome aberrations, including as well as excluding gaps, and micronucleated PAMs in smoke-exposed animals, compared to controls, indicated genotoxic capacity of MC smoke. The increases significantly correlated with the "concentration" of the gas. Mitotic indices also showed a significant and concentration-dependent increase. The frequencies of chromosome aberrations and MN following 7-day exposure were very similar to those for 1-day exposure. This was probably due to the transient nature of PAMs. A post-exposure gap of 24 h, compared to the 16-h gap, yielded a higher incidence of both mitoses and chromosome aberrations.

Animals↗
PubMed1989

Investigations of amitraz neurotoxicity in rats. III. Effects on motor activity and inhibition of monoamine oxidase.

The formamidine pesticide amitraz (AMZ) produces many behavioral and physiological changes in rats. We examined the dose effect and time course of AMZ on motor activity, monoamine oxidase (MAO) activity, and acetylcholinesterase (AChE) activity to evaluate possible neurochemical mechanisms for the behavioral effects of AMZ. For motor activity studies, male Long-Evans hooded rats were tested in photocell activity measurement devices. AMZ produced dose-related decreases in motor activity of rats allowed free access to food and rats maintained at a stable body weight through food restriction. Lowest effective doses of AMZ tested were 1-3 mg/kg, administered 20 min before testing. AMZ appeared to be about three times more potent in food-restricted rats, indicating that amount of body fat may play a significant role in the pharmacokinetics of AMZ. Motor activity returned to control levels over 4-5 days after dosing with 100-200 mg/kg AMZ, whereas recovery was evident the day after administration of low doses (1-30 mg/kg). Inhibition of MAO was measured in whole brain of rats sacrificed at various times after dosing with AMZ. Only greater than or equal to 100 mg/kg AMZ inhibited MAO, which was measurable within 2 hr of dosing and lasted up to 7 days. AMZ appeared to be more selective for type B MAO when given in vivo, although MAO-A was also inhibited at doses greater than or equal to 300 mg/kg. However, no selectivity was indicated by the IC50 values determined in vitro (IC50 = 31 and 28 microM for MAO-A and MAO-B, respectively). AMZ produced only negligible inhibition of AChE at the highest doses administered in vivo or at 10 mM in vitro. These data indicate that while AMZ does inhibit MAO, the dose range over which it produces this action is much higher than that which suppressed motor activity. Thus MAO inhibition is probably not responsible for AMZ-induced alterations in motor activity.

Animals↗
PubMed2005

A mathematical model for assessing control strategies against West Nile virus.

Since its incursion into North America in 1999, West Nile virus (WNV) has spread rapidly across the continent resulting in numerous human infections and deaths. Owing to the absence of an effective diagnostic test and therapeutic treatment against WNV, public health officials have focussed on the use of preventive measures in an attempt to halt the spread of WNV in humans. The aim of this paper is to use mathematical modelling and analysis to assess two main anti-WNV preventive strategies, namely: mosquito reduction strategies and personal protection. We propose a single-season ordinary differential equation model for the transmission dynamics of WNV in a mosquito-bird-human community, with birds as reservoir hosts and culicine mosquitoes as vectors. The model exhibits two equilibria; namely the disease-free equilibrium and a unique endemic equilibrium. Stability analysis of the model shows that the disease-free equilibrium is globally asymptotically stable if a certain threshold quantity (R0), which depends solely on parameters associated with the mosquito-bird cycle, is less than unity. The public health implication of this is that WNV can be eradicated from the mosquito-bird cycle (and, consequently, from the human population) if the adopted mosquito reduction strategy (or strategies) can make R0<1. On the other hand, it is shown, using a novel and robust technique that is based on the theory of monotone dynamical systems coupled with a regular perturbation argument and a Liapunov function, that if R0>1, then the unique endemic equilibrium is globally stable for small WNV-induced avian mortality. Thus, in this case, WNV persists in the mosquito-bird population.

Algorithms↗
PubMed2004

Malaria: control strategies, chemoprophylaxis, diagnosis, and treatment.

Malaria caused by Plasmodium falciparum continues to be the principal medical threat to travelers in tropical zones. Eighty percent of malaria cases occur in sub-Saharan Africa. Prevention capacity nears 100%. In the event of infection, early diagnosis and bitherapy (treatment that includes two different active molecules) provide a nonfatal outcome. The greatest risk occurs in the weeks after returning home. The history of malaria has shown that it is important to anticipate the evolving nature of the disease and to be able to respond to it in a timely fashion. The efficiency of preventive treatments should lead toward the goal of zero malaria cases when dealing with travelers; however, virtually all empiric experience indicates that this goal rarely is reached.

Animals↗
PubMed2004

Co-exposure to pyridostigmine bromide, DEET, and/or permethrin causes sensorimotor deficit and alterations in brain acetylcholinesterase activity.

Military personnel deployed in the Persian Gulf War (PGW) were exposed to a combination of chemicals, including pyridostigmine bromide (PB), DEET, and permethrin. We investigated the dose-response effects of these chemicals, alone or in combination, on the sensorimotor performance and cholinergic system of male Sprague-Dawley rats. Animals were treated with a daily dermal dose of DEET and/or permethrin for 60 days and/or PB (gavage) during the last 15 days. Neurobehavioral performance was assessed on day 60 following the beginning of the treatment with DEET and permethrin. The rats were sacrificed 24 h after the last treatment for biochemical evaluations. PB alone, or in combination with DEET, or DEET and permethrin resulted in deficits in beam-walk score and longer beam-walk times compared to controls. PB alone, or in combination with DEET, permethrin, or DEET and permethrin caused impairment in incline plane performance and forepaw grip strength. PB alone at all doses slightly inhibited plasma butyrylcholinesterase activity, whereas combination of PB with DEET or permethrin increased its activity. Brainstem acetylcholinesterase (AChE) activity significantly increased following treatment with combinations of either DEET or permethrin at all doses, whereas the cerebellum showed a significant increase in AChE activity following treatment with a combination of PB/DEET/permethrin. Co-exposure to PB, DEET, and permethrin resulted in significant inhibition in AChE in midbrain. PB alone or in combination with DEET and permethrin at all doses increased ligand binding for m2 muscarinic acetylcholine receptor in the cortex. In addition, PB and DEET together or a combination of PB, DEET, and permethrin significantly increased ligand binding for nicotinic acetylcholine receptor. These results suggest that exposure to various doses of PB, alone and in combination with DEET and permethrin, leads to sensorimotor deficits and differential alterations of the cholinergic system in the CNS.

Acetylcholinesterase↗
PubMed2004

Phragmalin limonoids from Chukrasia tabularis.

Six phragmalin limonoids, named tabulalin and tabulalides A-E, were isolated from the root bark of Chukrasia tabularis (Meliaceae). Their structures were determined by spectroscopic methods, and their antifeedant properties evaluated.

Animals↗
PubMed2005

Absorption and evaporation of N,N-diethyl-m-toluamide from human skin in vitro.

The penetration of DEET through split-thickness cadaver skin was measured in non-occluded Franz cells placed either in a fume hood or on a laboratory workbench. DEET, dissolved in a small volume of ethanol and spiked with (14)C radiolabel was applied to skin at doses from 0.02 to 11000 microg/cm(2). DEET penetration was greater for cells placed on the workbench, and the percentage of radioactivity penetrated after 72 h increased gradually with dose, for doses up to 680 microg/cm(2). At higher doses, it declined. Percent penetration ranged from 11.5 +/- 3.2% for a dose of 0.021 microg/cm(2) in the fume hood to 71.9 +/- 5.5% for a dose of 260 microg/cm(2) on the workbench. Results were interpreted in terms of a diffusion/evaporation model having three parameters-a solubility value for the chemical in the upper stratum corneum, M(sat); a mass transfer coefficient for evaporation, k(evap); and a characteristic time for diffusion, h(2)/D. The parameters obtained from fitting the model to the data (normalized to the fume hood environment) were M(sat) = 18 microg/cm(2) and k(evap) = 2.6 x 10(-5) cm/h. The value of h(2)/D decreased from 16 h at a DEET dose of 25 microg/cm(2) to 10 h at 1480 microg/cm(2), consistent with an increase in skin permeability of about 1.5-fold over this dose range. This effect was confirmed by means of an additional study in which skin samples pretreated with increasing amounts of unlabeled DEET were washed and redosed with (14)C-benzyl alcohol. A small (1.7-fold), but significant, increase in benzyl alcohol penetration with increasing amount of DEET was obtained. Thus, DEET enhanced its own skin permeation rate as well as that of another compound, but the effect was modest and not likely to be a major concern for compounds coadministered with DEET.

Abdomen↗