Search PubMed⌕ Search

Biomedical subjects

J J Doyle

Publications and source records attributed to J J Doyle.

At least 91 records · Page 5Linked to original sources
PubMed1980

Studies on Trypanosoma (nannomonas) congolense III. Antigenic variation in three cyclically transmitted stocks.

Cyclical transmission of different variable antigen types of Trypanosoma congolense STIB 228 resulted in the development of metacyclic trypanosome populations which were similar in their variable antigen composition as judged by immunofluorescence and neutralization assays. The variable antigen types present in the ingested bloodstream populations were not found in the metacyclic populations. The bloodstream populations which were obtained from cyclically infected, irradiated (900 rad.) mice contained variable antigen types which were not present in the corresponding metacyclic populations. When derivatives of 2 other stocks of T. congolense, isolated in different area of Tanzania, underwent cyclical development in the tsetse fly, the metacyclic populations of each stock also had a characteristic variable antigen composition. The metacyclic populations of the 3 stocks were, however, completely dissimilar in variable antigen composition. Simultaneous infection of tsetse flies with a mixture of different stocks resulted in the concurrent production of metacyclic trypanosomes which contained the characteristic variable antigen types of each stock. The effect of cyclical transmission on the process of antigenic variation in T. congolense infections is therefore similar to that in T. brucei infections.

Animals↗
PubMed1980

Studies on Trypanosoma (nannomonas) congolense IV. Experimental immunization of mice against tsetse fly challenge.

Groups of mice were exposed to multiple bites by tsetse flies (Glossina morsitans morsitans) infected with a clone of Trypanosoma congolense spread over a periof of 8 days. The mice were subsequently treated with Berenil 10 days after the first fly bite as were uninfected control mice. The group of mice which received 12--15 infectious fly bites on two occasions, 21 days apart, were subsequently resistant to infection when re-challenged by flies infected with the same clone of T. congolense. These mice were also immune to challenge by flies infected with a different bloodstream variable antigen type derived from this same stock. The immunity was stock-specific and directed against the metacyclic forms of the parasite, but was short-lived.

Animals↗
PubMed1980

Antigenic variation in clones of animal-infective Trypanosoma brucei derived and maintained in vitro.

Eighteen clones of variable antigen type 052 of Trypanosoma brucei stock S.427 were derived and maintained as animal-infective bloodstream forms in vitro for up to 60 days of cultivation. The antigenic composition of such clones was monitored weekly by immunofluorescent analysis of viable trypanosomes, using antisera raised to isolated variant-specific surface glycoproteins of both 052 and variable antigen type (221) which consistently appeared in the first relapse population of type 052 in vitro. The appearance of new variants was detected in 9 of the 18 clones 18--46 days following initiation of the clone and variable antigen type 221 was found in all 9 clones. On one or more occasions in 8 of such clones, viable trypanosomes were found which did not react with either antiserum but were mouse-infective on the 4 occasions tested and probably represent other variable antigen types. The process of antigen variation in vitro appears to resemble the process in vivo except that new variant types are detected earlier in vivo. This possibly results from different growth rates of the trypanosomes in vivo and in vitro, together with the fact that elimination of the initial variant population by the host's immune response facilitates the detection of newly arising variable antigen types in vivo.

Animals↗
PubMed1980

In vitro cloning of animal-infective bloodstream forms of Trypanosoma brucei.

Clones of animal-infective bloodstream forms of Trypanosoma brucei (stocks S.427 and LUMP 227) were made by transferring a single organism from bloodstream-form cultures into each well of Microtest II Tissue Culture Plates containing bovine fibroblast-like feeder cells. When the number of trypanosomes increased to 10(2)--10(3)/well on days 4--16, they were transferred into plastic T-25 culture flasks also containing feeder cells and fresh medium. Cultures were thereafter maintained by partially replacing the trypanosome suspension with the same volume of fresh medium (diluting the density to 2--5 x 15(5) trypanosomes/ml) every 24 h. Sub-cultivations could be made by transferring 1--2 ml of the trypanosome suspension to a new culture flask at 4--5 day intervals. A total of 42 clones in the 3 series TC221, TC52 and TC227, carrying variable antigen types (VATs) 221, 052 and ILTat 1.4, respectively, have been established. Average population doubling times for clones of TC221, TC52 and TC227 were 8.7, 14.5 and 15.5 h respectively. Of 35 populations examined, 34 clones retained the original specificity of their VATs for at least 8--32 days from cloning. One cloned population of TC52 consisted of 99.8% VAT 052 and 0.2% VAT 221 at the time when the first VAT test was made on day 18.

Animals↗
PubMed1980

Genetic and nongenetic factors affecting the elemental composition of human and other animal tissues--a review.

The genetic and nongenetic factors affecting the elemental composition of animal and human tissues are presented. Genetic factors include: (1) some well-known inherited diseases that affect copper, zinc, iron, magnesium, manganese and selenium metabolism; (2) animal species differences and (3) breed differences within animal species. The nongenetic factors include regional variation, dietary concentration of elements, interactions between elements, dietary concentration of other nutrients, chemical form of elements, age, sex, hormones, pregnancy, disease, temperature and altitude.

Acrodermatitis↗
PubMed1980

Analyses of variable antigen gene rearrangements in Trypanosoma brucei.

For the purpose of investigating the genetic basis of antigenic variation in Trypanosoma brucei, we have analyzed the structure of the genome surrounding the gene coding for one T. brucei variable antigen (ILTat 1.2) in several T. brucei clones expressing this and other variable antigens. In each case there are two copies of the gene. We found no evidence of an extra copy associated with the expression of this gene. Differences were found between the two copies in a single clone, and between the copies in different clones. The differences could be explained by insertion and deletion of various lengths of DNA in a region beyond the C-terminal end of the gene. Differences in genomic structure were found even between clones expressing the same antigen, whether ILTat 1.2 or another. Thus, no feature of the rearrangements observed can be correlated with the expression of a particular antigen.

Animals↗
PubMed1978

Studies on Trypanosoma (nannomonas) congolense. I. On the morphological appearance of the parasite in the mouse.

The pleomorphism of bloodstream Trypanosoma (Nannomonas) congolense was studied during the course of the first parasitaemic wave in mice using cloned and uncloned derivatives of three recent field isolates. The different morphological types were identified using the criteria described by Godfrey (1960). It was found that at any point of parasitaemia there were several morphological types of the parasite present, ranging from short to long forms. In the rising phase of parasitaemia, the short forms predominated, while at peak parasitaemia the parasites were highly pleomorphic, with significant proportions of short and "intermediate" forms although the long forms predominated. Pleomorphism was observed both in normal and in lethally irradiated (900 R) mice, even when the infection was initiated using a single organism. Such pleomorphism may result from physiological differences between the different forms of this parasite since these morphological types of T. congolense also differed in their ability to infect a new mammalian host.

Animals↗
PubMed1978

Studies on Trypanosoma (nannomonas) congolense II. Observations on the cyclical transmission of three field isolates by Glossina morsitans morsitans.

Teneral flies of Glossina morsitans morsitans were fed on mice infected with cloned and uncloned derivatives of three recent field isolates of Trypanosoma (Nannomonas) congolense. Flies with mature infections were identified by the warm-slide probe method and phase-contrast microscopy. High infection rates were achieved when such flies were fed on mice at peak parasitaemia. The infection rates were low when flies were fed on mice prior to or late after peak parasitaemia. The duration of the developmental cycle of T. congolense in the tsetse fly varied from 7 to 40 days: in 45% of the infective flies the developmental cycle was completed within 12 days; and in 76%, within 18 days.

Animals↗
PubMed1977

African trypanosomes: cultivation of animal-infective Trypanosoma brucei in vitro.

Trypanosoma brucei grew in the presence of bovine fibroblast-like cells in Hepes-buffered RPMI 1640 medium with 20 percent fetal bovine serum for more than 220 days at 37 degrees C. The organisms grown in this system were infective to mammalian hosts, retained the morphological and biochemical characteristics of long slender bloodstream forms, and displayed variant-antigen on their surfaces.

Animals↗
PubMed1977

Cultivation of bloodstream Trypanosoma brucei.

Animal-infective forms of Trypanosoma brucei (Strain 427) were successfully propagated in HEPES-buffered RPMI 1640 medium in the presence of bovine fibroblast-like cells for over 310 days. The organisms grown in this system were morphologically identical to the long slender bloodstream forms, retained their infectivity for mammalian hosts, and displayed variant-antigen on their surface. Technical details for establishing such bloodstream form cultures are described in the present paper.

Animals↗
PubMed1977

Stabilization and preservation of the antigenic specificity of Trypanosoma (Trypanozoon) brucei variant specific surface antigens by mild fixation techniques.

Living bloodstream trypansomes fixed by suspension in a 1% formalin solution maintain both their morphology and the immunological specificity of their variant specific surface glycoprotein, so allowing precise identification of the variant types present in a trypanosome population by direct or indirect immunofluorescence combined with phase microscopy. The technique is simple, adaptable to the study of low parasitaemias and should facilitate analysis of the phenomenon of antigenic variation both in the field and the laboratory.

Animals↗