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Biomedical subjects

A R Gray

Publications and source records attributed to A R Gray.

At least 19 recordsLinked to original sources
PubMed1994

Acute appendicitis in children: when does ultrasound help?

Fifty-six patients with possible appendicitis were evaluated clinically and by ultrasound. Ultrasound examination visualized the appendix in 18 of the patients evaluated and showed another pathology in six others. It was useful when the clinical picture was not clear (25 patients) as it showed an inflamed appendix in 10 patients. This was of particular value when there was another critical illness making clinical evaluation difficult (three patients), and for the diagnosis of other unsuspected pathological conditions (six patients). It did not affect the line of management when the clinical picture was clear enough to diagnose or exclude acute appendicitis.

Acute Disease↗
PubMed1991

Predominant cultivable flora in pericoronitis.

The predominant cultivable flora in pericoronitis was investigated by culturing pus from affected sites in 20 patients. Twenty colonies were picked at random from non-selective plates and identified using conventional biochemical and physiological tests, analysis of metabolic end-products by gas chromatography and protein profile analysis. The most frequently isolated organisms were Prevotella (Bacteroides) intermedia, Peptostreptococcus micros, Veillonella species, Fusobacterium nucleatum and Streptococcus mitis. Porphyromonas (Bacteroides) gingivalis was not isolated and asaccharolytic Eubacterium species were virtually absent. The predominant cultivable microflora in pericoronitis was found to be highly anaerobic in nature and superficially similar to that found in chronic periodontitis, although proposed marker organisms of severe periodontitis were absent.

Adolescent↗
PubMed1990

A pigmented adenomatoid odontogenic tumor.

Occasional reports have described the presence of melanin in various odontogenic lesions. A case of melanin pigmentation in an adenomatoid odontogenic tumor is described.

Adolescent↗
PubMed1983

Infection, immunity and the development of local skin reactions in rabbits infected with cyclically-transmitted stocks of Trypanosoma congolense.

The development of local skin reactions following bites by tsetse flies (Glossina morsitans) infected with Trypanosoma congolense was observed in normal rabbits, in rabbits with concurrent infections with T. congolense and in rabbits challenged after immunization by infection and treatment. Local reactions developed in normal rabbits within seven days of fly bite and were resolved by approximately 19 days after infection. In rabbits with concurrent infections no typical local reactions developed when they were bitten by infected tsetse flies. By allowing a single infected fly to bite a rabbit sequentially it was established that suppression of reaction development to homologous secondary challenge occurred within three to eight days of primary infection. Suppression of reaction development also occurred in infected rabbits challenged with an antigenically heterologous trypanosome stock within 14 to 18 days of primary infection, suggesting that reaction suppression is not associated with the specific immune response. It was also found that no neutralizing antibodies had developed against the parasites used for secondary infection by 28 days post-challenge. Rabbits were immunized by allowing an infected tsetse fly to feed on a rabbit and seven days later, when local reactions had appeared, treating it with homidium chloride. All rabbits challenged within 75 days of immunization by a tsetse fly infected with a homologous trypanosome stock resisted re-infection and some animals were immune up to 300 days after treatment. In most of the immunized animals specific neutralizing antibody activity against homologous parasites was low, suggesting that local expression of immunity in the skin might be more important in resistance to cyclically transmitted infections than serum antibodies. No local reactions developed on immune rabbits challenged with a homologous trypanosome stock but immunized rabbits challenged with heterologous trypanosome stocks developed typical local reactions.

Animals↗
PubMed1983

Interference with anti-trypanosome immune responses in rabbits infected with cyclically-transmitted Trypanosoma congolense.

Rabbits were infected with two clones of antigenically distinct stocks of Trypanosoma congolense transmitted through Glossina morsitans. Local skin reaction development and the appearance of neutralizing antibodies were followed in animals infected with one or other of the trypanosome stocks, with both stocks simultaneously or with both stocks consecutively. There was little difference in local skin reaction development on rabbits infected with a single stock or with both stocks simultaneously but, in rabbits exposed to a heterologous stock 14 or 21 days after a primary infection reactions were reduced in size or completely absent. Neutralizing antibodies against metacyclic-derived trypanosomes were detected 21 days after infection in animals infected with a single trypanosome stock and, in rabbits infected with both stocks simultaneously, antibodies against each stock were also detected 21 to 28 days after infection. In rabbits challenged 14 or 21 days after primary infection the appearance of trypanocidal antibodies against the stock used for challenge was delayed from 28 to 49 days.

Animals↗
PubMed1981

The use of culture-derived metacyclic trypanosomes in studies on the serological relationships of stocks of Trypanosoma brucei gambiense.

Metacyclic trypanosomes of five stocks of Trypanosoma brucei gambiense were produced in vitro in tsetse head-salivary gland explant cultures and used to infect rabbits. Sera were collected from the rabbits and monitored by agglutination tests for antibody production to nine serotype antigens of T. b. gambiense. In the case of a Nigerian stock of T. b. gambiense the sequences of antibody production were found to be similar in animals infected with the stock transmitted by tsetse flies and from culture. Many similarities were also found between the patterns of antibody production in rabbits infected with stocks of T. b. gambiense from Senegal, Nigeria, Zaire and Uganda. The occurrence of similar serotypes in geographically different stocks of T. b. gambiense provides further support for continuing efforts to develop improved serodiagnostic tests for sleeping sickness based on variable trypanosome antigens and to find techniques for immunoprophylaxis.

Animals↗
PubMed1980

Use of antigens of cultured Trypanosoma brucei in tests for bovine trypanosomiasis.

MicroELISA tests for the detection of trypanosomal antibodies in cattle infected with Trypanosoma brucei, T. vivax and T. congolense were carried out using antigens prepared from culture forms and bloodstream forms of T. brucei. Antigens prepared from culture forms gave similar microELISA values to those obtained with bloodstream form antigens and statistical analysis of the results obtained with both antigen preparations and sera from the infected animals showed significant high positive correlation. It would thus be possible to use culture from antigens as an alternative to bloodstream form antigens in diagnostic tests for trypanosomiasis, with the advantage that culture form antigens are more easily prepared free from extraneous protein.

Animals↗
PubMed1980

Changes in the levels of some serum enzymes in dromedary camels infected with Trypanosoma evansi.

The serum levels of sorbitol dehydrogenase, alkaline phosphatase, glutamic pyruvic transaminase and glutamic oxaloacetic transaminase in healthy male dromedary camels were determined. The camels were then infected with Trypanosoma evansi and the same enzymes determined at intervals, both during the period of infection and after treatment with the trypanocidal drugs suramin and quinapyramine sulphate. Increases in the serum levels of sorbitol dehydrogenase, glutamic pyruvic transaminase and glutamic oxaloacetic transaminase were recorded, together with a decrease in the serum level of alkaline phosphatase during the period of patent parasitaemia. The levels of the enzymes returned to normal after drug treatment.

Alanine Transaminase↗
PubMed1979

Serodiagnosis of infection with Trypanosoma evansi in camels in the Sudan.

Five diagnostic tests for infection with Trypanosoma evansi have been compared in groups of camels experimentally infected or exposed to natural infection in the Sudan. The correlation of positive results obtained by assays of IgM levels, the mercuric chloride test and the formol gel test with the presence of active infection was unsatisfactory, but there was a good correlation between results obtained using IFAT and ELISA and proven infection. Sera from a high proportion of apparently uninfected camels from endemic areas gave positive reactions with all 5 tests, possibly indicating inadequate parasitological diagnosis or persistence of antibody after unsatisfactory chemotherapy. It was concluded that serological tests using trypanosomal antigens to detect antibodies were more sensitive for diagnosis than indirect tests based on raised euglobulin levels. Serodiagnostic tests may therefore have a place in future programmes for surveillance and control of T. evansi infections in camels.

Animals↗
PubMed1979

Observations on the antigenicity and serological relationships of stocks of Trypanosoma congolense from East and West Africa.

Antigenic relationships of 4 stocks of Trypanosoma congolense from different parts of Africa were examined by immunofluorescence (IFAT) and neutralization tests. Antisera to each stock were obtained from rabbits infected with trypanosomes transmitted by Glossina morsitans. Trypanosomes for use as antigens were obtained from local skin reactions developing on rabbits infected with 2 of the stocks. Using the IFAT and antisera at end-point dilutions approximately 40% of the trypanosomes fluoresced strongly and a further 30% less intensely with homologous antisera, indicating antigenic heterogeneity among the trypanosomes developing in the skin. Using antisera at low dilutions some samples gave cross-reactions with trypanosomes of heterologous stocks, but at higher dilutions there were no cross-reactions with either of the antigens. The lack of cross-reactions at high antiserum dilutions was interpreted as indicating antigenic differences between the 4 trypanosome stocks. Using neutralization tests only homologous antisera reduced the infectivity of trypanosome suspensions. Overall, these observations indicated that there were at least 3 different strains of T. congolense among the 4 stocks examined.

Animals↗
PubMed1979

Trypanosomes in the lymph nodes of cattle and sheep infected with Trypanosoma congolense.

The prefemoral lymph nodes of two calves and a sheep infected with a stock of Trypanosoma congolense transmitted by Glossina morsitans were examined histologically for the presence of trypanosomes. Ten days after infection trypanosomes were found in the subcapsular sinuses of the nodes of a calf and the sheep but parasites were absent from the blood at this time. Trypanosomes were also detected in the prefemeral lymph node of the other calf on examination 30 days after infection, when parasites were also present in the blood. These observations provide further evidence that extravascular foci of trypanosomes develop in infections with T congolense and indicate that it should not be regarded as a strict plasma parasite.

Animals↗