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D Pye

Publications and source records attributed to D Pye.

52 records · Page 3Linked to original sources
PubMed1979

A marsupial oncovirus?

A virus-like particle was observed in two continuous cell lines derived from the marsupial Sminthopsis crassicaudata (Fat-tailed Dunnart). The development of the particle was similar to the development of D-type oncoviruses. Initially, a crescentof nucleoid material was observed near the nucleus in the region of the Golgi apparatus. This crescent developed into a doughnut-shaped-A-type particle which migrated through the cytoplasm towards the cell membrane where it budded either into a smooth membrane cytoplasmic vacuole or from the cell membrane. Only enveloped A-type particles were observed; no mature B-type, C-type or D-type particles were detected.

Animals↗
PubMed1979

Simple focus assay for Encephalitozoon cuniculi.

In this is vitro infectivity assay for Encephalitozoon cuniculi, lesions due to the organism appeared as macroscopically distinct foci. The number of such foci was used as a direct measure of the number of infectious units in the original sample. The expected correlation between focus-forming units and 50% infectious doses was observed in limit dilution experiments.

Cell Line↗
PubMed1979

Independence of convergence and divergence: norms, age trends, and potentiation in mechanized prism vergence tests.

Motor-driven prism stereoscope vergence tests, base in break, base in recovery, base out break, and base out recovery, repeated three times (BIB, BIR, BOB, BOR X 3) were given to three separate groups. Two instruments with different speeds were used. Repeated testing shows a slight trend to convergence in slower machines. The results from both machines are still comparable. Means are similar to previously published norms from hand-turned instruments, but the variance of scores is about twice as large and there is an eso trend at near. The motor drive aids discrimination, since Ss who are capable can now follow with smooth vergences over a wider range. In general, there is no substantial trend with age between 3 and 25 years other than those which may be due to decreasing response times. Vergence scores can be adequately reduced to two independent factors, loading on convergence and divergence, respectively, which suggests that there are two processes varying independently in maturation and therapy as well as assessment.

Adolescent↗
PubMed1977

Marsupial cells in long-term culture.

Cell lines have been developed from several species of Australian marsupials and studied during long-term growth. Cell lines developed from macropodid skin or heart tissues all had reproducible finite life-spans. However, cell lines developed from dasyurids showed bariable behavior in culture: lines developed from Antechinus stuartii and Dasyurus viverrinus had finite life-spans, while lines developed from Sminthopsis crassicaudata had indefinite life-spans. S. crassicaudata lines usually became heteroplloid, but one was still diploid after 150 population doublings, while another contained a proportion (10%) of haploid cells. Other lines were developed from the peramelid, Perameles nasuta, and the phanlngerid, Trichosurus vulpecula.

Animals↗
PubMed1977

Isolation of Encephalitozoon cuniculi from urine samples.

Encephalitozoon cuniculi was isolated from the urine of infected rabbits using human and canine tissue cultures. The organism was isolated from 7 of 11 contaminated urines from seropositive animals. The advantages of urine over tissue as a source of E. cuniculi are that it is obtainable from living animals, can be examined for the presence of organisms, and is essentially free of cells likely to overgrow the tissue cultures used for isolation.

Animals↗
PubMed1977

Application of immunofluorescence to the establishment of an Encephalitozoon cuniculi-free rabbit colony.

Serologic screening of a rabbit breeding colony over a 9-month period showed that all 9-week-old rabbits with Encephalitozoon cuniculi infection were born of E cuniculi-infected does. This observation, obtained from studies on 395 young rabbits, suggested that transmission of infection is either transplacental or the result of close contact soon after birth. On this basis, 16 young healthy rabbits, seronegative to E cuniculi, were isolated and tested at 2-week intervals for antibodies to E cuniculi. In the first 2 months, seven rabbits showed indications of developing antibodies to E cuniculi and were immediately removed from the colony. The remaining rabbits along with their 52 offspring were tested for serum antibodies for a further 16 months and no rabbit became seropositive. Eight months after establishment of the colony, three does, one buck and six 12-week-old rabbits were killed. Macroscopic and extensive histologic and immunofluorescence examinations failed to reveal any evidence of infection with E cuniculi. These results showed that serological screening for E cuniculi infection by immunofluorescence is a simple yet adequate procedure for establishing a rabbit colony free of encephalitozoonosis.

Animals↗
PubMed1975

Rapid detection and isolation of mycoplasmas from cell cultures.

An improved medium for the isolation of Mycoplasma species from contaminated cell cultures is reported. A modification of the mycoplasma detection method using the uridine/uracil uptake ratio method is described. Results obtained using this method with mycoplasma contaminated cell cultures and with contaminated cell cultures treated with the antibiotic Lincomycin are presented.

Animals↗
PubMed1975

Serodiagnosis of nosematosis by immunofluorescence using cell-culture-grown organisms.

This simple procedure for the detection of serum antibodies to Nosema cuniculi in rabbits and other host species incorporates indirect immunofluorescence and uses as antigen N. cuniculi isolated from urine and cultured in a human fibroblast-like cell line derived from foetal tongue. Examination of rabbit sera from 8 institutions indicated that no institution was free from Nosema infection. The prevalence of infection in 4 separate Australian rabbit colonies varied from 25 to 75%.

Animals↗
PubMedDate not supplied

Immunisation with recombinant AMA-1 protects mice against infection with Plasmodium chabaudi.

The Plasmodium merozoite surface antigen apical membrane antigen-1 (AMA-1) has previously been shown to provide partial protection to Saimiri and rhesus monkeys immunised with recombinant Plasmodium fragile or parasite-derived Plasmodium knowlesi AMA-1, respectively. In the study reported here we have used the Plasmodium chabaudi/mouse model system to extend our pre-clinical assessment of an AMA-1 vaccine. We describe here the expression of the full-length Plasmodium chabaudi adami AMA-1 and the P. chabaudi adami AMA-1 ectodomain using both baculovirus and Escherichia coli. The ectodomain expressed in E. coli, which contained an N-terminal hexa-his tag, was purified by Ni-chelate chromatography and refolded in vitro in the presence of oxidised and reduced glutathione to generate intramolecular disulphide bonds. In a series of vaccine trials, in both inbred and outbred mice, highly significant protection was obtained by immunising with the refolded AMA-1 ectodomain. Protection was shown to correlate with antibody response and was dependent on intact disulphide bonds. Passive transfer of antibodies raised in rabbits against the refolded AMA-1 ectodomain was also protective. In view of this demonstration that E. coli expression of a soluble P. chabaudi AMA-1 domain can generate a vaccine that is effective in mice, we are pursuing a similar approach to generating a vaccine against P. falciparum for testing in human volunteers.

Animals↗
PubMedDate not supplied

High titer response against a malarial antigen depends on the flanking sequence of the immunizing peptide conjugate.

The immunogenicity of peptides conjugates containing the epitope STNS, recognized by inhibitory monoclonal antibodies directed against the Plasmodium falciparum merozoite surface antigen MSA2, was investigated. The sequence of the flanking regions was critical in determining the response against the central epitope. In the best immunogen tested, this flanking sequence was not related to the sequence of the surface antigen itself but nevertheless gave rise to a strong anti-MSA2 protein response as judged by Western blotting and immunofluorescence. This finding illustrates the importance of defining such flanking sequences in optimizing peptide based vaccines.

Animals↗