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Biomedical subjects

J F Walsh

Publications and source records attributed to J F Walsh.

At least 37 records · Page 2Linked to original sources
PubMed1985

Identification of adults of the Simulium damnosum complex using hydrocarbon analysis.

Using advanced gas liquid chromatography in association with multivariate statistical analysis, a study of four members of the S. damnosum complex - S. sirbanum, S. damnosum s.str., S. yahense and S. sanctipauli, revealed that both adult male and female flies could be distinguished by quantitative analysis of the cuticular hydrocarbon peaks. Adult flies were obtained from sites which were known to contain a very high proportion of pure cytospecies. The females of the complex were more readily separated from each other than were the males. On the basis of preliminary results, the technique provides for the first time, a reliable method for distinguishing S. sirbanum and S. damnosum s.str., the most important vectors of onchocerciasis in the savanna areas of West Africa, as well as an additional method for identification of adult S. sanctipauli and S. yahense. Analysis of the hydrocarbons by GC/MS showed them to be straight chain and branched saturated hydrocarbons ranging from C22-C35. The technique is simple in respect of field methods of collection, and thus holds considerable promise as a means of identifying S. damnosum complex flies throughout the area of onchocerciasis transmission in Africa.

Africa, Western↗
PubMed1984

Training for day-case dental anaesthesia. Oxygen saturation during general anaesthesia administered by dental undergraduates.

Sixty-seven patients undergoing general anaesthesia for exodontia as outpatients were studied in order to measure the levels of oxygen saturation. Both the anaesthesia and extractions were performed by fourth year dental undergraduates working under direct supervision. Falls in oxygen saturation in excess of 5% were found in three groups of patients receiving 20%, 25%, and 30% oxygen in the inspired mixture.

Adolescent↗
PubMed1983

Fine needle cytology of thyroid.

Fine needle aspiration cytology (FNAC) of thyroid nodules is a useful diagnostic technique. The cases of 107 patients with pathological changes in the thyroid are reviewed. Nine carcinomata were found--seven of which showed abnormal cytology. There was one false negative but no false positive result. The role of FNAC in pre-operative evaluation of thyroid nodules is discussed.

Biopsy, Needle↗
PubMed1982

Measurement of gastric emptying after gastric bypass surgery using radionuclides.

The pattern of gastric emptying has been assessed after gastric bypass surgery using a double isotope technique for measuring solid and liquid emptying with a scintillation camera. Eleven control subjects and 12 patients, 12 months post-gastric bypass, were studied. Stomal and gastric pouch size were assessed at endoscopy. Solid emptying was slower and liquid emptying was more rapid after gastric bypass surgery. Initial rapid emptying of solid occurred in the 4 patients with the smallest pouch diameters. There was no correlation between stomal size and rates of solid or liquid emptying nor between the weight loss produced by the operation and the rates of solid or liquid emptying, stoma or pouch size.

Adult↗
PubMed1981

Identification of two West African black flies (Diptera: Simuliidae) of the Simulium damnosum species complex by analysis of cuticular paraffins.

Simulium damnosum is known to be a sibling species complex with at least 24 cytotaxonomically distinct forms in Africa. Of these, six occur in the area of West Africa covered by the World Health Organization Onchocerciasis Control Programme. They are all vectors of Onchocerca volvulus, and several are capable of migrating great distances. We report here a comparatively simple chemical method of species identification using individual adult females of pooled samples that have been collected and stored dry in glass vials. Females of two species, S. sirbanum and S. squamosum, were identified by extraction and analysis of cuticular components using gas chromatography. Statistically significant differences were seen between these two species for each of five sets of consistently appearing peaks that were quantitated and compared. The technique has considerable potential for use in the field since extracts or specimens may be stored indefinitely at ambient temperature before analysis.

Animals↗
PubMed1981

Further studies on the reinvasion of the onchocerciasis control programme by Simulium damnosum s.l.: the effects of an extension of control activities into southern Ivory Coast during 1979.

During 1979 the aerial larviciding operations of the Onchocerciasis Control Programme were extended southwestwards to cover those areas with Ivory Coast where the savanna cytospecies of the Simulium damnosum complex were known to breed. This resulted in a marked reduction of the reinvasion which threatened the Programme in Ivory Coast and Upper Volta in earlier years. Previous conclusions concerning the location of sources of invading populations and consequently the direction and distance of the movements of flies were substantiated. It was confirmed that S. damnosum s. str. and S. sirbanum were the main migrant species. In this area S. Squamosum was shown to be of much less importance as a migratory vector.

Cote d'Ivoire↗
PubMed1981

Studies on biting Simulium damnosum s.l. at a breeding site in the Onchocerciasis Control Programme area during and after an interruption of insecticidal treatments.

The increase of population of biting S. damnosum s.l. at a breeding site situated within the Onchocerciasis Control Programme area of West Africa following a temporary cessation of insecticidal treatments was studied by making every day collections on human bait at five catching sites and for 2--3 days per week at seven others, between 17 January and 9 April 1977. Observations on pupal and larval densities, water and air temperatures, relative humidity and water level were also made. The results showed that there was an interval of 23 days between the last application of insecticide and the appearance of the first nulliparous biting flies. This coincided with the finding of the first S. damnosum larvae. Subsequently, the biting densities increased following a geometric progression from about 10 flies per day to a maximum of 188 per day, giving a daily rate of increase of 1.07. Ten days after the re-application of insecticide, biting densities had fallen to about 5% of the pre-control level giving a daily rate of decrease of 0.74. Very little dispersion was observed with biting rates falling to 5% at 3000 m. perpendicular to the river. At these sites nullipars predominated. Conversely along the axis of the river densities at 1000 m away had to only 68% and were composed mainly of parous flies. Studies on diel activity showed the greatest biting activity between 15.00 h and 18.00 h with a lesser period of activity between 07.00 and 10.00 h. The significance of these observations in future planning of control strategy is discussed.

Animals↗
PubMed1980

The effect of gypsum products and separating materials on the typography of denture base materials.

The typography of polymethyl methacrylate processed against various gypsum products coated with various separating materials was studied under an SEM. Tinfoil and two commercial tin foil substitutes were used as separating material during processing, and the surfaces of the resulting acrylic resin forms were studied for topographical differences. Tinfoil and alpha 2 hemihydrates produced the smoothest surfaces. As a practical solution, a good quality tinfoil substitute and alpha 1 hemihydrate could be used when processing polymethyl methacrylate resin.

Acrylic Resins↗
PubMed1980

Sticky trap studies on Simulium damnosum s.l. in northern Ghana.

The results of sticky trapping S. damnosum s.l. at several sites in northern Ghana are given. Yields were always very much lower than those which could be obtained by human bait catches, and caught flies tended to disappear from traps which were not emptied at least daily. Thus the technique offered little promise as a means of monitoring population fluctuations. Nevertheless some valuable information was obtained. Colour choice studies showed that hunting flies were attracted to dark blue substrates. In all situations the most shaded surfaces of the traps were preferred by alighting flies. The presence of S. damnosum in the canopies of trees was demonstrated for the first time. Flies were caught at heights above 6 m at three sites, the maximum height being 9.2 m, the height of the topmost trap. Among flies caught in the canopy of trees were nulliparous, parous and gravid females as well as males. Only in one catch, at relatively low levels in riverine trees, were blood engorged flies a noteworthy proportion of the catch.

Animals↗
PubMed1979

Displacements of Simulium damnosum and strategy of control against onchocerciasis.

Regular aerial treatment of 14 000 km of watercourses has achieved and maintained, over an area of 700 000 km2 of West African savannah, a very high degree of control of the larvae of Simulium damnosum sensu stricto and S. sirbanum, the vectors of onchocerciasis in this area. However, particular and relatively restricted parts of this area, mainly in northern Ivory Coast and neighbouring parts of Upper Volta, experience regular and prolonged reinvasions by parous female vectors, which have already taken bloodmeals (and many of them carrying the parasites) and arrive from unknown sources probably hundreds of kilometres away, from directions probably between southwest and north. This reinvasion, now experienced in three successive years, represents the outstanding scientific, epidemiological and logistic problem still facing the WHO Onchocerciasis Control Programme. An outline is presented of the multidisciplinary investigations being undertaken to find a solution.

Africa, Western↗
PubMed1979

Root retention and removable partial denture design.

The position of a retained root for preservation of a ridge requires modification of the design of a distal-extension removable partial denture on the side of the retained root. A model with silicone rubber over the ridges and simulated retained roots was fabricated. A framework with mesial rests, distal proximal plates, and I-bar clasp arms was fitted to it. A pencil lead was attached to the framework to record the arcs of rotation of the I-bar clasp arm. The movements and the fulcrums of the prosthesis were changed by the presence of simulated retained roots posterior to the distal abutment.

Dental Abutments↗
PubMed1979

Entomological aspects of the first five years of the Onchocerciasis Control Programme in the Volta River Basin.

The history and structure of the WHO Onchocerciasis Control Programme in the Volta River Basin are described. An outline of the vector control operations is given, and the techniques and organisation of the entomological evaluation network are described in detail. During the course of the evaluation and related studies undertaken between November 1974 and October 1978 almost 1.2 million S. damnosum females have been taken in over 52,000 man days of catching, and 674,000 flies were dissected. An assessment based on this effort using Annual Biting Rates and Annual Transmission Potentials shows that the transmission of O. volvulus has been reduced to below a defined maximum permissible level over most of the central part of the Programme Area. The difficulties encountered in the remainder, and at certain problem sites are outlined and relevant data given. The benefits to be expected from extending the area further southwards and the possibilities of later reductions in control activity are discussed.

Africa, Western↗
PubMed1979

Studies on the reinvasion of the Onchocerciasis Control Programme in the Volta River Basin by Simulium damnosum s.I. with emphasis on the south-western areas.

The aerial larvicidng operation of the Onchocerciasis Control Programme of the World Health Organization which began in February 1975 resulted in a sharp reduction in Simulium damnosum numbers. However, at the onset of the rainy season the fly population increased in certain areas. Detailed surveys both on the ground and by helicopter did not reveal any significant failures of treatments that could account for the fly densities observed, and it was concluded that the flies must originate from sources outside the controlled zone. This reinvasion proved to be an annual occurrence which has been studied in detail between 1975 and 1978 in the south-western parts of the control zone. The methods used included full day catches by vector collectors carried out every day throughout the season, cytotaxonomic determination of larvae, detailed morphological examination of reared and biting adults and treatment of suspected source rivers with insecticide. The results indicate that the invasion takes place in a SW-NE direction across country for distances of 300 km or more along the track of the monsoon winds. It involves mainly the savanna cytospecies S. damnosum s. str. and S. sirbanum. The invading populations are composed of older parous flies, many of which carry infective 3rd stage larvae indistinguishable from those of Onchocerca volvulus. These females tend to bite close to the rivers and do not disperse as far as normal populations with a higher proportion of younger flies.

Animals↗