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Biomedical subjects

E E Davis

Publications and source records attributed to E E Davis.

At least 19 recordsLinked to original sources
PubMed1998

Tolerance to the bronchoprotective effect of salmeterol 12 hours after starting twice daily treatment.

BACKGROUND: Regular use of salmeterol has been associated with reduced bronchoprotective effect against methacholine as early as 24 hours after initiating treatment. OBJECTIVE: To determine whether loss of the bronchoprotective effect measured one hour after salmeterol could be demonstrated 12 hours following one previous dose. METHODS: Ten subjects with stable, mild asthma were enrolled in a randomized, placebo-controlled, double-blind, crossover study comparing two 2-dose treatment periods: (1) blinded salmeterol 50 microg inhaled at bedtime, followed by unblinded salmeterol 50 microg inhaled 12 hours later and (2) blinded placebo inhaled at bedtime, followed by unblinded salmeterol 50 microg inhaled 12 hours later. The methacholine PC20 was measured one hour after the morning salmeterol; FEV1 was measured just prior to the morning salmeterol dose and at the start of the methacholine inhalation test. RESULTS: The mean log methacholine PC20 recorded one hour after a single dose of salmeterol (1.20 +/- 0.17 SE) was significantly higher than the mean log methacholine PC20 recorded after two doses of salmeterol at 12-hour intervals (1.00 +/- 0.16 SE; P = .024). The mean FEV1 12 hours after salmeterol was significantly higher than the mean FEV1 recorded 12 hours after placebo (P = .0017), however, there was no significant difference between the FEV1 recordings one hour after the two unblinded doses of salmeterol. CONCLUSIONS: Tolerance to the bronchoprotective effect of salmeterol against methacholine induced bronchoconstriction occurs extremely quickly as it is evident 12 hours after starting twice daily treatment.

Administration, Inhalation↗
PubMed1996

Olfactory control of mosquito behaviour.

The following papers will tell us much about our current knowledge of certain aspects of the olfactory control of mosquito behaviour-specifically host-locating behaviour. More importantly, as we read the papers, we should pay attention to the insights they will provide about what is not known and to the questions that our lack of knowledge should raise. The authors will also provide us with some new approaches and methodologies that we can apply to the study of mosquito physiology and behaviour.

Animals↗
PubMed1994

Sensory physiological basis for attraction in mosquitoes.

Hematophagous insects use air-borne chemical cues to guide them to resources such as blood-meal hosts, plants, and oviposition sites. Research that combines behavioral and electrophysiological approaches to the study of how insects find these resources can result in useful information about what chemical signals a mosquito can detect and at what airborne concentrations such compounds are effective. Such studies have helped clarify the role of lactic acid, ammonia, carbon dioxide, octenol, phenols, temperature, and humidity in the attraction of mosquitoes, tsetse flies, and ticks to blood-meal hosts. Egg raft pheromone, indoles, cresols, methyl cyclohexanol, 2-butoxy ethanol, and fatty acid esters have been examined with respect to oviposition site location and selection. Plant volatiles have received less attention but electrophysiological responses to terpenes and green plant volatiles have been observed. Information from studies of this type can be useful in the design of both attractants and more effective repellents.

Animals↗
PubMed1992

Effect of the repellent deet on the antennal chemoreceptors for oviposition in Aedes aegypti (Diptera: Culicidae).

The insect repellent, N,N-diethyl-m-toluamide (deet), interferes with detection of the host attractant, lactic acid (LA), by LA-excited neurons on the antennae of female Aedes aegypti (L.) mosquitoes. In the current laboratory behavioral experiment, the attraction of gravid female mosquitoes to a source of ethyl propionate, an oviposition attractant, was reduced by a factor of two when deet was present. Similarly, when deet was presented together with ethyl propionate in electrophysiological experiments, sensitivity of the neural response to ethyl propionate was depressed in a transient, dose-dependent manner that could account for the reduction in behavioral attraction of gravid females to ethyl propionate. Electrophysiologically, the sensitivity of oviposition attractant receptors to ethyl propionate on gravid females was not different from that on nongravid host-seeking females. The similarity between the depression of sensitivity of the oviposition attractant-sensitive neurons induced by deet and that observed in the host attractant-sensitive neurons suggest a common mode of action of deet on peripheral chemoreceptor neurons that mediate these behaviors.

Aedes↗
PubMed1989

Effect of acute respiratory acidosis on multimodality sensory evoked potentials of Long-Evans rats.

Auditory, visual and somatosensory evoked potentials (EPs), recorded epidurally from 31 chronically implanted male Long-Evans rats, were studied to examine the pattern of sensory effects caused by hypercapnia. Recordings were obtained before exposures, 10-20 min after the beginning of exposure to CO2 in synthetic air, and 30 min after the end of exposure. Previous recordings revealed no substantial effects of the extended recording period itself. Blood pH during an average exposure of 18.8% CO2 was about 7.1. During this level of CO2 exposure the somatosensory response was almost completely abolished, but the latencies of early detectable components were not affected. In contrast, the latencies of all brainstem auditory evoked response components and the 1-5 interwave time increased, whereas amplitudes were only slightly affected. Amplitudes and latencies of early and late components of the flash EP were decreased and lengthened, but the after-discharge components appeared to be most sensitive to CO2. Concentration-response relationships were examined by exposure of rats to 8 and 16% CO2. The most sensitive EP parameter was average amplitude of the late somatosensory EP components. These results suggest that EPs might be useful for assessing acute metabolic disturbances as well as more commonly assessed neurologic disorders.

Acidosis, Respiratory↗
PubMed1989

The effects of allatectomy and juvenile hormone replacement on the development of host-seeking behaviour and lactic acid receptor sensitivity in the mosquito Aedes aegypti.

Host-seeking behaviour in newly emerged Aedes aegypti (L.) females is not expressed immediately after adult eclosion but develops gradually over a period of approximately 3-4 days. This development is accompanied by an apparent maturation of the antennal chemosensory afferent neurons involved in the detection of the airborne host attractant lactic acid. Since these events coincide in time with juvenile hormone-dependent previtellogenic ovarian growth and since the expression of other reproduction-associated behaviour has previously been shown to be dependent on juvenile hormone, the effects of juvenile hormone removal and replacement on the development of host-seeking behaviour and the response characteristics of the lactic acid-sensitive receptors were investigated. No effect of juvenile hormone removal by allatectomy or juvenile hormone replacement or augmentation by topical application of the juvenile hormone mimic methoprene was found. It was concluded that this hormone is not involved in the appearance of host-seeking behaviour or the apparent maturation of the lactic acid receptors that occurs during early imaginal life.

Aedes↗
PubMed1979

Conservation of reference strains of Fusarium in pure culture.

More than 300 reference strains representing 60 species and varieties of Fusarium cultures named according to different taxonomic systems are currently maintained at the American Type Culture Collection (ATCC). They have been preserved by freeze-drying and by freezing and subsequent storage in liquid nitrogen (-196 degrees C) to insure their viability without contamination, variation, mutation, or deterioration. The materials and procedures used at the ATCC for the acquisition, accessioning, cataloguing, preservation and distribution are described. Longevity storage data for the strains available for distribution are presented and discussed.

Freeze Drying↗
PubMed1979

In vivo evaluation of a high-strength, high-ductility stainless steel for use in surgical implants.

A high-strength, high-ductility, austenitic stainless steel has been evaluated for use in surgical implants by performing in vivo tests in rats, rabbits, dogs, and rhesus monkeys. This stainless steel, a TRIP (Transformation Induced Plasticity) steel containing about 4% Mo, was compared with two alloys in current clinical use: Type 316L stainless steel and cast Vitallium. Compared with the other two alloys, cast Vitallium generally had higher resistance to corrosion and superior biocompatibility in all animals. The tests in rats and dogs indicated that the corrosion resistances of the TRIP steel and the Type 316L stainless steel were similar and that the tissue reactions caused by these alloys were also similar. However, in rhesus monkeys, the TRIP steel was shown to be susceptible to stress-corrosion cracking and much more susceptible to crevice corrosion than Type 316L stainless steel. Limited tests in rabbits supported the observation that the TRIP steel is susceptible to stress-corrosion cracking. These inconsistencies in the in vivo tests underline the need for a reevaluation of the popular test techniques and of the animals commonly chosen for assessing the suitability of candidate implant materials. The "worst case" results from the rhesus monkey tests were entirely consistent with previous results obtained from in vitro studies. However, further work must be performed before the behavior of metals in humans, rhesus monkeys, or any other animal, can be predicted with confidence from an in vitro test program.

Animals↗
PubMed1976

Reproducibility of vitamin assays with mutants of Neurospora crassa maintained by freeze-drying.

Three mutant strains (ATCC 9277, ATCC 9278, ATCC 9683) of Neurospora crassa requiring choline, inositol, and p-aminobenzoic acid respectively for normal growth were deposited at the ATCC by G.W. Beadle 30 years ago and were preserved at various time intervals by freeze-drying. Each preservation batch yielded cultures that, when used for biological assays, exhibited the same biochemical properties as they originally possessed. The freeze-drying technique is shown to be applicable to preserving biological properties of sporulating fungi for bioassay over prolonged periods of time.

Biological Assay↗