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Biomedical subjects

D A Denham

Publications and source records attributed to D A Denham.

At least 109 records · Page 6Linked to original sources
PubMed1977

Immunity to Trichinella spiralis. VII. Resistance stimulated by the parenteral stages of the infection.

In three experiments mice were given three intravenous injections of Trichinella spiralis newborn larvae produced in vitro. Following a challenge infection of newborn larvae the mice were shown to be on the average 85% resistant i.e., only 15% of the challenge larvae developed to encysted muscle stage larvae in these mice; when the challenge consisted of normal muscle larvae administered per os, the mice were 51% resistant. Neither the number nor longevity of adult worms in the intestines was affected by this immunization procedure.

Administration, Oral↗
PubMed1976

Laboratory evaluation of a new technique for counting microfilariae in blood.

The technique involves taking a measured volume of blood (20-40 mm3) from a finger or ear prick on to a conventional 3 X 1 in microscope slide and lysing it with water. Microfilariae could either be counted immediately, whilst still alive, or the smear dried, fixed and stained. A comparison between counts of microfilariae in freshly prepared slides and stained slides showed that few microfilariae were lost in the staining process.

Animals↗
PubMed1976

Studies on Brugia pahangi. 13. The anthelmintic effect of compounds F151 (Friedheim), HOE 33258 (Hoechst) and their reaction product.

F151 was a potent filaricide against adult Brugia pahangi in cats and jirds. HOE 33258 did not kill adult worms in cats but had a marginal effect on adult worms in the peritoneal cavity of jirds. It was not immediately microfilaricidal in cats but the microfilarial counts of treated cats fell within a few weeks of treatment. The reaction product, or mixture, of these two compounds (V5851 = E) was strongly macrofilaricidal in cats and jirds.

Animals↗
PubMed1976

Studies with Brugia pahangi. 14. Intrauterine development of the microfilaria and a comparison with other filarial species.

The intrauterine development of Brugia pahangi embryos was followed from after fertilization to birth, using light and electron microscopy. The origin and development of the sheath of the microfilaria and its possible role in the nutrition of the developing embryo were particularly investigated. Comparisons were drawn with the intrauterine development of other filarial species. The egg shell of the B. pahangi embryo is distinct from the oolemma and forms the sheath of the microfilaria. It is suggested that the electron dense material released by cells of the uterine wall and passing along the channels between the egg shells of adjacent embryos is nutritive. The death of large numbers of developing embryos in the central uterine lumen is probably caused by overcrowding as their size rapidly increases, leading to nutritional deficiency.

Animals↗
PubMed1976

Studies with Brugia pahangi 12. The activity of levamisole.

The effects of levamisole on adults, third stage infective larvae, and microfilariae of Brugia pahangi were studied in in vitro culture and in vivo against developing stages in the vector mosquito and in infected cats. In vitro the drug was effective only at dose levels much higher than can be tolerated by mammals. It was active against the developmental stages of the worm in the vector Aedes aegypti. The drug was strongly microfilaricidal in cats but less effective against adult worms.

Aedes↗
PubMed1976

The anthelmintic effects of a new compound "E" (Friedheim) on Onchocerca gutturosa in the cow--a possible tertiary screening system for drug action against O. volvulus in man.

Three cows were treated with different levels of compound "E" which is known to have strong filaricidal activity. In all three animals the number of microfilariae of Onchocerca gutturosa declined after treatment. At autopsy most of the adult worms found were dead and in those still living embryogenesis appeared to have ceased. It is concluded that, despite the disadvantages, this system represents a possible way of assessing onchocercicidal activity before undertaking human trials.

Animals↗
PubMed1975

The relationship between length of incubation, bacterial growth and tuberculin yield of a strain of Mycobacterium tuberculosis.

The relationship was studied between length of incubation in a liquid synthetic medium, amount of bacterial growth, pH of the culture filtrate and tuberculin yield of a single strain, DT, of Mycobacterium tuberculosis. No sinple relationship was found between the total crop of bacteria and the tuberculoprotein content of the culture filtrate. On the other hand, protein release and the pH of the culture filtrate were closely related. In each of two trials the bacterial crop increased rapidly during the early period of incubation, although maximum growth was not reached until 9 and 13 weeks respectively. The pH of the culture filtrate reached its maximum at a value of more than 9-0 after 5 weeks incubation and then fell until the 10th week; a second rise occurred until the 13th week when the pH dropped again and levelled off slightly on the alkaline side of neutrality. The rate of increase in tuberculin yield was most rapid during the first 7 weeks of incubation. After this, the rate of increase slowed down but the yield was still rising after 18 weeks. It is concluded that for the large-scale production of mammalian tuberculin by the method used in these trials, it is profitable to incubate production cultures for 14 weeks or longer.

Alanine↗
PubMed1975

Studies with Brugia pahangi 10. An attempt to demonstrate the sharing of antigenic determinants between the worm and its hosts.

Infective stage Brugia pahangi that were reared in Aedes aegypti survived equally well in cats that had previously been immunized against mosquito tissue and in a normal cat. The survival of third, fourth, juvenile, adult and microfilarial stages of B. pahangi that were recovered from cats was similar in jirds that had been immunized against cat antigens and in normal jirds. Host antigenic determinants were not detected on the surface of larvae in substantial amounts using fluorescent antibody techniques. It is unlikely that B. pahangi evades the immune response of its vertebrate hosts by masquerading as "self" behind host antigens.

Aedes↗
PubMed1975

Studies with Brugia pahangi. III: Histological changes in the affected lymph nodes of infected cats.

Cats infected with Brugia pahangi by single or repeated inoculation of infective larvae for different periods of time, were autopsied and the affected lymph nodes examined histologically, stained with methyl green and pyronin Y, haematoxylin and eosin, Lendrum's eosinophil stain, Mallory's trichrome stain or the May-Grunwald Giemsa technique. In single infections, there was initially a cell-mediated type immunological response which was characterized by proliferation of mononuclear thymus-dependent cells in the paracortical region of the lymph node. The antibody-type response became more evident as the infections progressed. This response was characterized by proliferation of lymphocytes in rapidly enlarging germinal centres and the production of large numbers of plasma cells in the cortico-medullary junction and medullary cords of the nodes. In long term infections, the affected afferent lymphatic vessel and popliteal node were almost obliterated by fibrous tissue, but an inguinal lymph node complex usually developed to replace lymphatic filtration in the limb. Repeated infections produced more complicated changes. Both types of response occurred to varying degrees throughout the infection. No significant increase in mast cells or eosinophil cells was seen. Fibrous tissue increased in the lymph nodes only after long periods of infection; such nodes often became non-functional, and by-passed by new lymphatic vessels.

Animals↗