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Biomedical subjects

H V Smith

Publications and source records attributed to H V Smith.

106 records · Page 6Linked to original sources
PubMed1980

Studies on the incidence of Toxocara and Toxascaris spp. ova in the environment. 1. A comparison of flotation procedures for recovering Toxocara spp. ova from soil.

Seven different flotation fluids were assessed for their efficiency in recovering Toxocara canis ova from artificially seeded soil samples. Using the most efficient (a saturated solution of magnesium sulphate plus 5% potassium iodide) 25 g amounts of 234 environmental soil samples were examined for the presence of Toxocara spp. and Toxascaris ova. Twenty-six samples (11.1%) yielded ova of one or other species. There was no discernible pattern of distribution of positives with relation to the source of the samples. The maximum number of ova recovered in any one sample was 19. All the ova recovered from the environment were considered viable and potentially infective.

Animals↗
PubMed1979

The acquisition of antigens in the intercellular substance of mouse skin by schistosomula of Schistosoma mansoni.

Serum from patients suffering from the autoimmune skin disease pemphigus vulgaris has been used to demonstrate the presence of intercellular substance (ICS) on the surface of these chistosomula of Schistosoma mansoni which has penetrated mouse skin in vitro or during a percutaneous infection. ICS was absent from mechanically transformed schistosomula or those formed in the peritoneal cavity of mice. Schistosomula which penetrated mouse skin rapidly in vitro acquired very little of the ICS. It was found during a percutaneous infection that schistosomula recovered from the skin after 10 min had no detectable ICS, while those recovered after 2 hr and 24 hr gained increasing quantities of the material. It is concluded that schistosomula which are delayed in their exit from the skin acquire more ICS. However, this material must be shed during subsequent migration since schistosomula from lung and liver, and 7-week-old worms do not posses it. The implications of the findings are discussed.

Animals↗
PubMed1979

The immune response of pigs to infection with the stomach worm Hyostrongylus rubidus (Hassall and Stiles, 1892). III. Effect of a primary infection on immunoglobulin-positive cell numbers.

An immunofluorescent study has been made of IgG, IgM and IgA in the stomach of uninfected minimal disease pigs and pigs infected with a single dose of 100,000 third stage infective Hyostrongylus rubidus larvae. Immunoglobulin-positive cells were present in both uninfected and infected animals. In infected animals both IgM and IgA immunocytes increased in numbers following infection and the numbers remained raised during the histotropic phase of worm development. No increase in IgG immunocyte numbers was noticed throughout the course of infection (100 days).

Agglutinins↗
PubMed1979

Antigens of Hyostrongylus rubidus, the red stomach worm of pigs. Analyses by means of passive haemagglutination and immediate hypersensitivity tests.

Antigens were prepared from different stages of worm development and adult worm antigens were fractionated by ion exchange and exclusion chromatography. The antigens, or fractions of them, were assessed for their activity in passive haemagglutination reactions or intradermal tests. The results of the passive haemagglutination reactions indicated that circulating agglutinins were more readily detected when adult stage specific antigens were used. Antigen prepared from worms isolated when the population was declining was less sensitive. Fractions of adult worm antigen did not confer greater sensitivity than the whole worm extract.

Animals↗
PubMed1977

Immunofluorescent patterns in the skin in Besnier's prurigo. The eczema asthma syndrome.

The immunofluorescent patterns in the skin of eighteen patients with Besnier's prurigo were studied at different stages of eczematous lesions. The presence, distribution pattern, and numbers of immunoglobulin and complement-positive lymphocytes in twenty-nine biopsies are reported. In all cases IgE-positive lymphocytes were present in both clinically uninvolved and involved skin. IgG, IgM and IgE-positive lymphocytes showed a characteristic distribution pattern in the dermis. In the acute stages IgM deposition was prominent in the basement membrane zone and it is suggested that damage to the basement membrane results in diffusion of immunoglobulin and complement into the epidermis. These features were not present in a control group of normal skin and of other dermatoses.

Adolescent↗
PubMed1976

The passive transfer of humoral immunity from sows infected with Hyostrongylus rubidus (Hassal and Stiles, 1892), the red stomach worm, to their offspring and its significance in the conferring of protective immunity.

Sows repeatedly infected with large single doses of third stage infective Hyostrongylus rubidus larvae show an anamnestic circulating agglutinin response to the parasite as detected by the passive haemagglutination reaction. At farrowing the circulating antibody level dropped, whereas the colostral agglutinating antibody level increased for a period of a few hours. The predominant class of immunoglobulin which had agglutinating activity against H. rubidus was IgG. Offspring which had suckled the infected mothers had a demonstrable agglutinin titre 4 days after birth, whereas offspring which suckled non-infected mothers had no demonstable agglutinins. On infection of the offspring, those which suckled infected mothers showed a more rapid and pronounced increase and duration of circulating agglutinins than those which had suckled noninfected mothers. The parasitic burden, as determined by the duration of egg laying and total egg output, was considerably lower for the group reared on the infected mothers. These experiments show that passively transferred agglutinating antibodies, mainly of the IgG class, were associated with protection.

Agglutinins↗
PubMed1975

Coin value and perceived size: a longitudinal study.

Decimalization of the Irish currency presented an opportunity to study the perceived size of coins as they were introduced or withdrawn and to examine the accentuation of differences between coins. Estimates were obtained of the sizes of 4 coins from 478 subjects in 3 groups tested at different times: just after decimalization, 2, or 3 yr. later. A newly introduced coin was significantly underestimated in size at first but came to be significantly overestimated later, while all familiar coins were always significantly overestimated. The amount of overestimation of a coin depended on its value, not its size, leading to an accentuation of the difference between any two coins if the larger coin was also the more valuable but sometimes to the opposite if the smaller coin were of higher value than the larger member of the pair.

Adolescent↗
PubMedDate not supplied

Inter-laboratory comparison of the CD-1 neonatal mouse logistic dose-response model for Cryptosporidium parvum oocysts.

cryptosporidium parvum oocyst viability can be determined by vital dyes, in vitro excystation, and cell culture; however, neonatal mouse infectivity assays are the reference method. Unfortunately, there have been few efforts to standardize methods for infectivity assays thus casting a veil of uncertainty over the significance and comparability of results. In order to address this issue, two laboratories proficient in measuring oocyst infectivity conducted independent dose titration studies with neonatal CD-1 mice using standardized protocols and a well-characterized isolate of Cryptosporidium parvum. The resulting independent logistic dose-response models derived by regression analysis were compared with each other and with a published model. The comparisons showed these dose-response functions to be reproducible under standardized conditions. It is important to standardize mouse strain, age of mice at inoculation and necropsy, oocyst isolate, and age of oocysts. However, other factors, including methods used to detect infectivity and to count oocyst doses, appear less critical. Adopting a standardized assay for oocyst infectivity will provide both a basis for comparing data from various oocyst disinfection studies and a suitable platform for evaluating new or existing in vitro viability surrogates such as excystation, vital dyes or cell culture.

Animals↗