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Biomedical subjects

D M Spratt

Publications and source records attributed to D M Spratt.

At least 37 records · Page 2Linked to original sources
PubMed1990

The role of helminths in the biological control of mammals.

Biological control of invertebrates has been successful while that of vertebrates has been, with the exception of myxomatosis in rabbits, unsuccessful; reasons for this are discussed. Demographic studies of small mammals suggest that population regulation occurs by several different mechanisms, more than one of which may be acting at the same time. Coevolution is an important phenomenon in host-parasite associations, nevertheless parasites may limit host population abundance. The basis of the regulatory effect on the host population is that parasite-induced host mortality or reduction in fecundity is density-dependent. Increasing evidence of the density-dependent effects of helminths on host survival and reproduction is forthcoming from laboratory studies but has not been confirmed in the field. The theory that a helminth parasite may regulate mammal population abundance has been verified recently in the laboratory. A multidisciplinary research programme aimed at understanding the mechanisms responsible for formation of house mouse (Mus domesticus) plagues and seeking strategies to reduce mouse numbers is discussed. One aspect of the work involves investigation of the potential of the nematode, Capillaria hepatica, as a biological agent in the control of wild mice in the cereal-growing regions of Australia. Biological control of mammals is viewed within the context of integrated pest management. A helminth species which reduces host survival or fecundity at an increasing rate as host abundance increases has a role in host population regulation. There is potential to capitalize on that role and apply the helminth as a biological agent in the control of mammals which have attained pest status.

Animals↗
PubMed1989

Lesions associated with metazoan parasites of wild platypuses (Ornithorhynchus anatinus).

Pathological findings associated with helminth and arthropod parasites of four wild platypuses (Ornithorhynchus anatinus) are described. Fourth-stage larval rhabditoid nematodes (?Cylindrocorporidae) found partially embedded in the stratum corneum were associated with mild acanthosis, orthokeratotic hyperkeratosis and inconstant subacute dermatits. A filarioid nematode (?Lemdaninae) was found in hypodermal lymphoid tissue. A larval trichostrongyloid nematode was found in the dermis, with no evidence of host response. An undescribed species of trombiculid mite ("chigger") was found in the pelage and attached to superficial stratum corneum. Focal inclusions of eosinophilic material within stratum corneum, interpreted as mite gel saliva produced during formation of the "stylostome," were also observed. The tick Ixodes ornithorhynchi punctured the epidermis causing adnexal trauma, dermal haemorrhage and chronic active dermatitis. The digenean Mehlisia ornithorhynchi was present in the small intestine of one animal and was associated with mild catarrhal enteritis.

Animals↗
PubMed1989

Patterns of cell proliferation and growth rate in limb bones of the domestic fowl (Gallus domesticus).

The growth rates of each extremity of the tibiotarsus (TibT) and tarsometatarsus (TMT) bones and of a phalangeal bone were measured in Rhode Island red chicks. Histological sections of the growth plates at each of these sites were made for measurements of the thickness of the flattened dividing cell layer and counts of the number of cells between its boundaries. The diameter of the mature chondrocytes in the metaphysis was also measured. The extent of the dividing cell population within the flattened cell layer and the proportion of cells in division were measured from autoradiographs prepared after labelling dividing cells in vitro or in vivo (three birds in each group) with tritiated thymidine. From the results the rate of cell production in the plane of growth at each growth plate was estimated. It varied from about six cells per day at each end of the phalanx to just over 50 cells per day at the proximal end of the TibT and TMT. The duration of the cycle time was estimated to be 13 to 21 hours at the proximal TibT and TMT and distal TibT but considerably longer at the distal TMT and at both ends of the phalanx. Variation in growth rate between extremities of the bones examined was associated largely with variation in the dividing cell populations and the thickness of the flattened cell layer, but it appears that there were also significant differences in cell cycle times between sites. The in vitro and in vivo labelling techniques gave comparable results.

Animals↗
PubMed1988

Ultrastructure and secretory nature of the seminal glomus in budgerigars (Melopsittacus undulatus).

The seminal glomera from captive budgerigars were dissected and prepared for ultrastructural and histochemical studies of the lining epithelia. The general structure suggested that they are formed by convolutions of the terminal portions of the ductus deferens which appear as a network of tubules. The epithelium lining the tubules was identified as pseudostratified ciliated and non-ciliated columnar epithelium. With the electron microscope it was possible to identify two different cell types in the epithelium: type 1, ciliated cells and type 2, non-ciliated epithelial cells. Light microscopy revealed periodic acid Schiff (PAS) positive material, resistant to diastase digestion in the distal parts of some of the epithelial cells, indicating its glycoprotein nature. Alcian blue/PAS staining showed mixed acidic and neutral glycoproteins. Alcian blue staining at different hydrogen ion concentrations (pH) showed that the acidic glycoprotein was of the weakly sulphated type. Periodic acid thiocarbohydrazide silver proteinase staining, at the ultrastructural level, confirmed the presence of an intracellular glycoprotein.

Animals↗
PubMed1982

Durikainema macropi gen. et sp. nov. (Muspiceoidea: Robertdollfusidae). A remarkable nematode from Macropodidae (Marsupialia).

Durikainema macropi gen. et sp. nov. (Muspiceoidea: Robertdollfusidae) is described from the mesenteric and hepatic portal veins of Macropus giganteus Shaw 1790, M. agilis (Gould 1842) and M. rufogriseus (Desmarest 1817) (Marsupialia: Macropodidae) from Queensland, Australia. It is also known from histological sections of hepatic portal veins of M. robustus Gould 1841, M. fuliginosus (Desmarest 1817) and Lagorchestes conspicillatus Gould 1842. The new genus resembles the Enoplina in cephalic and caudal characters and the Dorylaimina in other characters. Durikainema resembles Robertdollfusa Chabaud and Campana 1950 in its small form, absence of mouth oesophagus and anus, atrophied digestive tube, reduction of female genital apparatus to a uterine pouch, viviparity and cephalic cuticular inflation in larvae. It differs from this genus in its complex and well developed cephalic structures and its well developed body musculature in both sexes. Durikainema is tentatively placed in the Robertdollfusidae, Muspiceoidea. Larvae develop beyond firststage in the uterus of the female. They have been found in the non-peripheral blood of male and female M. giganteus, the lactating mammary gland of female M. agilis but not the non-lactating glands of the same female and in the deep capillaries of thigh skin of male M. agilis. Transmission of the parasite may be direct by a percutaneous or milk route, or indirect by a haemophagous arthropod.

Animals↗
PubMed1982

Anatrichosoma haycocki sp. n. (Nematoda: Trichuridae) from the paracloacal glands of Antechinus spp. With notes on Skrjabinocapillaria skarbilovitsch.

Anatrichosoma haycocki sp. n. (Nematoda: Trichuridae) is described from the paracloacal glands of Antechinus swainsonii (Waterhouse, 1840) and A. stuartii Macleay, 1841 (Marsupialia: Dasyuridae) from Nadgee State Forest, New South Wales, Australia. Immature male and female worms occur free in the intestine. A. haycocki is distinguished from other species of Anatrichosoma by the following suite of morphological characters: small size, absence of longitudinal cuticular striations in both sexes, subterminal constriction of male tail bearing 14 minute papillae and inflation of posterior portion of mature female giving Trichuris-like appearance. It is also characterised by its occurrence in paracloacal glands in a genus of small carnivorous dasyurid marsupial restricted to Australia and New Guinea. Skrjabinocapillaria rodentium Wertheim and Chabaud, 1979 is recognised as a synonym of Anatrichosoma gerbillis (Bernard, 1964). The genus Skrjabinocapillaria Skarbilovitsch, 1946 is placed as a synonym of Capillaria Zeder, 1800, resulting in the new combination for the type species: C. eubarsata (Skarbilovitsch, 1946) comb. nov. It is suggested that deep penetration of the female uterus by the male at insemination is a behavioural feature common to members of the Trichinelloidea and that the morphology of the male reproductive tract reflects the mechanisms of penetration employed by members of each genus.

Animals↗
PubMed1981

Prevalence of Fasciola hepatica infection in native mammals in southeastern Australia.

Fasciola hepatica infection was found in 5 of 12 marsupial and 1 of 3 eutherian species examined in southeastern Australia. Prevalence of infection in native mammals was as follows: Macropus giganteus, 59%; M. rufogriseus banksianus, 15%; Wallabia bicolor, 5%; Vombatus ursinus, 30%; Trichosurus vulpecula, 5%; and Rattus fuscipes, 4%. Collection sites were assigned to one of two categories. Prevalence was higher in macropodids collected on agricultural pastures grazed by sheep and cattle (category A) than in macropodid collected in forested areas variably grazed by livestock (category B). A high prevalence of infection (82%) was recorded in M. giganteus in an area from which sheep and cattle had been excluded for 15 years. Prevalence of F. hepatica infection in V. ursinus was similar in the two habitat categories; however, within forested areas infection was more common in V. ursinus collected near swamps and creeks than those taken from drier ridges. The presence of habitat suitable for the snail intermediate host. Lymnaea tomentosa, and utilization of this habitat by domestic and native mammals are important epidemiological factors. Moderate numbers of flukes (1-95) and faecal egg production (1-195 eggs per gram of faeces (EPG)) in M. giganteus and M.r. banksianus emphasize their suitability as hosts and contaminators of pasture. Small numbers of flukes and conspicuous hepatic lesions in V. ursinus suggest moderate resistance to infection. The low prevalence and small number of flukes in T. vulpecula was attributed to the arboreal habit of this host. R. fuscipes is susceptible to infection but infected individuals were found in only one of numerous forest areas with suitable snail habitat. Feeding behaviour is probably responsible for the absence of F. hepatica infection in W. bicolor and Rattus lutreolus in forested areas.

Animals↗
PubMed1981

The prevalence of anti-leptospiral agglutinins in sera of wildlife in southeastern Australia.

Anti-leptospiral agglutinins were found in the serum from 18 (7 species) of 419 (25 species) animals sampled from various areas of southeastern Australia. Positive serologic reactions were observed in 5 of 25 (20%) brush-tailed possum (Trichosurus vulpecula), 1 of 26 (3.8%) tammar wallaby (Macropus eugenii), 2 of 12 (16.7%) swamp wallaby (Wallabia bicolor), 1 of 3 (33.3%) koala (Phascolarctos cinereus), 3 of 41 (7.3%) common wombat (Vombatus ursinus), 2 of 100 (2%) bush rat (Rattus fuscipes) and 4 of 12 (25%) rusa deer (Cervus timorensis). The majority (55.5%) of serologic reactions were to serovar hardjo. No serologic reactions were observed in samples from echidna (Tachyglossus aculeatus), brown antechinus (Antechinus stuartii), swainson's antechinus (Antechinus swaisonsii), long-nosed bandicoot (Perameles nasuta), brown bandicoot(Isoodon obesulus), common ringtail (Pseudocheirus peregrinus), greater glider (Schoinobates volans), eastern grey kangaroo (Macropus giganteus), red-necked wallaby (Macropus rufogriseus), rabbit (Oryctolagus cuniculus), water rat (Hydromys chrysogaster), black rat (Rattus rattus), eastern swamp rat (Rattus lutreolus), broad-toothed rat (Mastacomys fuscus), fox (Vulpes vulpes), sambar deer (Cervus unicolor), hog deer (Axis porcinus) and fallow deer (Dama dama).

Agglutination Tests↗
PubMed1978

Onchocerca sweetae (Nematoda: Filarioidea): notes on the intermediate host.

Microfilariae of Onchocerca sweetae are broadly distributed in the superficial layers of the dermis of the water buffalo (Bubalus bubalis). A total of 2855 insects representing 20 species were collected from O. sweetae-infected bait buffaloes. Only one species, Culicoides sp. "M", ingested microfilariae from buffalo skin. Larval development of O. sweetae was observed in the thorax of this species. Atotal of 829 insects, representing 7 species and including 749 parous Culicoides spp. were collected from light and Manitoba traps. Developing filarioid larvae were observed only in Culicoides sp. "M". It is concluded that Culicoides sp. "M" is a natural intermediate host of O. sweetae in the Northern Territory of Australia.

Animals↗