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E Pearce

Publications and source records attributed to E Pearce.

29 records · Page 2Linked to original sources
PubMed1987

Vaccination against cutaneous leishmaniasis in a murine model. I. Induction of protective immunity with a soluble extract of promastigotes.

BALB/c mice can be protected against a fatal Leishmania major infection by immunization with whole radio-attenuated promastigotes; however, neither the antigens responsible for protection nor the protective immunologic mechanisms have been defined. In this study, the ability of promastigote fractions to elicit similar immunity to that obtained with whole organisms, and the immune responses associated with such protection were analyzed. Intraperitoneal immunization with a soluble, membrane-free parasite extract was found to induce protection against L. major challenge equal to that obtained with whole organisms. Induction of immunity (89% protection in seven experiments) was most effective with 100 micrograms of the soluble leishmanial antigen (SLA) and required concomitant injection of the bacterial adjuvant, Corynebacterium parvum (CP), followed by an i.p. boost of SLA alone 1 wk later. Vaccinated animals exhibited Leishmania-specific cell-mediated immunity, as assessed both by lymphocyte transformation and the production of macrophage-activating factors (MAF). In addition, although SLA + CP-immunized mice failed to exhibit delayed-type hypersensitivity (DTH) before challenge, splenic lymphocytes from these mice could transfer a local DTH reaction to naive recipients. Immunization also induced the production of antibodies against two major metabolically labeled proteins of m.w. 30,000 and 53,000, but failed to stimulate a detectable humoral response against promastigote surface antigens. Thus, these experiments demonstrate that vaccine-induced immunity against cutaneous leishmaniasis is strongly associated with the induction of cell-mediated immunity, but does not require the development of an antibody response to promastigote surface antigens. In addition, these studies establish the feasibility of employing soluble, nonmembrane-derived parasite material as a source of protective immunogens.

Adjuvants, Immunologic↗
PubMed1986

Induction of protective immunity against Schistosoma mansoni by a nonliving vaccine. IV. Fractionation and antigenic properties of a soluble adult worm immunoprophylactic activity.

An aqueous buffer-soluble, nonparticulate fraction of adult Schistosoma mansoni worms (SWAP) was separated by gel filtration on Ultragel AcA-34, and portions of the eluate were tested for their capacity to induce protective immunity against cercarial challenge when administered intradermally to mice in combination with the adjuvant BCG. All of the immunogenic activity was found in a single peak of protein excluded in the void volume of the column. This same fraction was determined by SDS-PAGE and Western immunoblotting to be unique in that it contained a component of Mr (X 10(-3) 97 (97,000) recognized monospecifically by antibodies from mice vaccinated with unseparated SWAP plus BCG. Similarly, the protective fraction was unique in possessing the capacity to elicit 24 hr delayed footpad swelling responses, as well as lymphokine production, in SWAP-BCG-immunized mice. These results suggest that the immunogenic activity of SWAP resides in a restricted population of molecules, and possibly in the 97,000 antigen detected with antibodies from vaccinated animals. Because both the protective capacity of unfractionated SWAP and the serologic reactivity of the 97,000 antigen are sensitive to digestion with protease, it is likely that the immunologic activity of these molecules is dependent on peptide-bonded structural elements.

Animals↗
PubMed1980

Effect of metoclopramide on interdigestive myoelectric activity in the conscious dog.

The effect of two-hour infusions of metoclopramide at five different doses on interdigestive intestinal electrical activity was studied in four conscious fasting dogs. Spike activity during the infusions was quantitatively compared with activity during preceding and following periods of saline infusion. The effect of the drug was the enhancement of spike activity during migrating myoelectric complexes (MMC) without disruption of the fasting pattern; the effect was most marked in the proximal small intestinal and diminished distally. As in other published studies with metoclopramide, its effects were variable and not dose dependent. The enhancement of the MMC by an exogenous stimulus, not previously reported, provides indirect evidence for cholinergic mediation of cyclical motor activity, and also suggests a rational basis for therapy.

Animals↗
PubMed1979

Quantitative effect of oral feeding on gastrointestinal myoelectric activity in the conscious dog.

Gastrointestinal myoelectric activity was recorded in seven studies in five dogs during two hours of fasting immediately followed by feeding and subsequent recording for four hours. In four studies serial plasma samples were taken for radioimmunoassay of insulin and gastrin. In all animals there was a significant reduction (P less than 0.01) in gastric basic electrical rhythm (BER) frequency on feeding which was sustained throughout the postprandial period. There was no change in the duodenal BER. Feeding induced a significant (P less than 0.01) increase in overall jejunal and ileal (but not duodenal) spike activity. Ileal (but not jejunal) spike activity again increased significantly (P less than 0.05) after the first two post-prandial hours. The changes in serum gastrin or in serum insulin did not appear to account for most of the observed changes in myoelectric activity, suggesting that other humoral and/or neural factors mediate the response to food.

Animals↗
PubMed1979

Dr. T. G. Ludwig.

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Dentistry↗
PubMedDate not supplied

Fluoride profiles in dental calculus from Japanese, Chinese and British residents.

Whether the fluoride concentrations and profiles differ in human dental calculus obtained from different countries was investigated. A total of 203 dental calculus deposits on 203 permanent teeth from residents (mean age, 52.1 years) of Nagoya (Japan), Shanghai (China), Leeds (Great Britain) and the Wuhan mountainous area (China, fluoridated area) were analysed. An abrasive microsampling procedure was used to examine fluoride distribution. There were five types of fluoride profiles in dental calculus in each area/country (designated types L, J, U, T, W). In supragingival calculus, type L (highest in the outermost layers) and type J (highest in the innermost layers) both had significantly higher values than type U (high in the surface and innermost layers) but were relatively identical. In subgingival calculus, type W (high in the outermost, mid and innermost layers) was characteristics. Calculus from the Wuhan mountainous area (fluoridated) had the highest fluoride concentration, followed by Leeds (non-fluoridated), and Nagoya and Shanghai (non-fluoridated) calculus had the lowest. Fluoride concentrations in supragingival calculus were higher in teeth extracted because of periodontal diseases than dental caries. It is concluded that fluoride concentrations and distribution in dental calculus differ from country to country, probably due to different fluoride environments.

Adult↗
PubMedDate not supplied

Fluoride in enamel lining pits and fissures of the occlusal groove-fossa system in human molar teeth.

The fluoride (F) distribution in enamel lining the occlusal fissures of human molars and premolars is difficult to investigate by normal microsampling techniques, yet this information is of importance as fissures are particularly susceptible to caries. We have used the proton probe to map the distribution of F and Ca in sections of 17 molar teeth collected from Danish and New Zealand populations. The caries status of the sectioned fissure was determined by microradiography or visually after drying. The probe scans were graphed as density images, surface plots and topographical plots. Sound enamel bordering grooves and fissures showed a high-F surface layer, in 1 sample approximately 60 microm wide near the fissure bottom but gradually widening to double this width near the fissure opening, and up to 200 microm wide in grooves, while underlying enamel had a low and almost constant F level. In this respect fissure and groove enamel resembled smooth surface enamel. The F concentration fluctuated along the surface layer, reaching maximum values ranging from 1,800 to 4,200 ppm in 5 non-carious fissures. Incipient caries in fissure enamel usually but not always resulted in an increase in F in the outer layer, the F maximum values in 5 such samples ranging from 1,900 to 7,200 ppm. F maximum values in outer enamel were higher in 7 samples showing advanced caries, 2, 700-10,000 ppm. The lesion subsurface body usually showed normal F values, as did carious dentine in the advanced lesions. The variable characteristics of the outer layer in sound fissure enamel are likely to be the result of a developmental process rather than environmental influences. The fact that we normally failed to find increased F concentrations in subsurface carious fissure enamel or in underlying carious dentine suggests that F does not diffuse into the deep part of fissure lesions, and probably has minimal effect on slowing the progress of such lesions, a suggestion in accord with clinical findings on the F effect on fissure caries.

Calcium↗
PubMedDate not supplied

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