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Biomedical subjects

J D Smyth

Publications and source records attributed to J D Smyth.

15 recordsLinked to original sources
PubMed1979

Isoelectric focusing of some enzymes from Echinococcus granulosus (horse and sheep strains) and E. multilocularis.

Extracts of the horse and sheep strains of Echinococcus granulosus and E. multilocularis were compared on the basis of their isoenzyme patterns for 10 enzymes by means of isoelectric focusing in polyacrylamide gels. The enzymes examined were: acid phosphatase, lactate dehydrogenase, malate dehydrogenase, malic enzyme, phosphoglucoseisomerase, isocitrate dehydrogenase, adenylate kinase, aldolase and alpha-glycerophosphate dehydrogenase. Interspecific and intraspecific differences are apparent in the isoenzyme profiles of all the enzymes except adenylate kinase; the pattern and activity of adenylate kinase are identical for both strains of E. granulosus but this enzyme clearly distinguishes these forms from E. multilocularis. The absence of electromorphic variation in any of the enzymes from either form of E. granulosus may be a result of the self-fertilizing hermaphraditism of these organisms.

Adenylate Kinase↗
PubMed1979

Attempts to immunize rats against infection with Fasciola hepatica using in vitro culture antigens from newly excysted metacercariae.

Attempts were made to immunise rats against Fasciola hepatica using the culture products obtained from the in vitro cultivation of newly excysted metacercariae. Three culture regimes were chosen: (1) medium NCTC 135 for 48 h (2) NCTC 135 + 20 per cent fetal calf serum (FCS) for 48 h (3) NCTC 135 + 20 per cent FCS for 14 days. The used culture medium from each of these regimes was concentrated, mixed with adjuvant and injected subcutaneously into rats. Similarly treated unused culture media was used in control rats. The rats were challenged with an oral dose of 20 F hepatica metacercariae 35 days later and autopsied 96 days after the start of the experiment. The fluke burdens in those rats which had received the culture antigens did not differ significantly from those in the control groups.

Animals↗
PubMed1979

Echinococcus granulosus and E. multilocularis: in vitro culture of the strobilar stages from protoscoleces.

The techniques for the in vitro culture of Echinococcus granulosus and E. multilocularis are described in detail. The sheep strain of E. granulosus was grown to sexual maturity but fertile eggs were not produced due to the failure to achieve insemination in vitro. The horse strain of E. granulosus grew only slightly in vitro and then ceases to develop, although remaining active for long periods. E. multiloculoris differentiated largely into unsegmented, sexually mature, "monozoic" forms; some organisms developed "pseudo-proglottids" with the interproglottid membrane absent or poorly formed. After prolonged culture, some strobila of E. multilocularis developed an extra scolex.

Animals↗
PubMed1978

Differences in the chemical composition and carbohydrate metabolism of Echinococcus granulosus (horse and sheep strains) and E. multilocularis.

Metabolic studies in vitro and studies on chemical composition indicate basic biochemical differences between the horse and sheep strains of Echinococcus granulosus and between these and the closely related species, E. multilocularis. The horse strain of E. granulosus has a similar level of DNA, but significantly more polysaccharides and lipids, with less RNA and protein than the sheep strain. E. multilocularis has significantly more lipids and DNA but less polysaccharides than the horse and sheep strains of E. granulosus, more RNA and protein than the horse strain but similar protein to and less RNA than the sheep strain. Incubations under air and under 95% N2-5% CO2 for 3 h show that only E. multilocularis takes up glucose, that all three forms consume different amounts of oxygen and endogenous glycogen and produce different concentrations of lactate, succinate, acetate, malate, pyruvate, propionate and ethanol as end products of carbohydrate metabolism.

Acetates↗
PubMed1978

Ultrastructural immunocytochemical localization of two hydatid fluid antigens (antigen 5 and antigen B) in the brood capsules and protoscoleces of ovine and equine Echinococcus granulosus and E. multilocularis.

The unlabelled antibody method was used in the ultrastructural localization of two hydatid fluid antigens, antigen 5 and antigen B, in brood capsules and protoscoleces of Echinococcus granulosus and E. multilocularis. Antigen 5 was found in the parenchyma cells of the protoscolex and brood capsule wall and to a lesser extent in the walls of the flame cells and collecting ducts of the excretory system and in the surrounding interstitial material. It is suggested that, while some excretion of this antigen may occur from the protoscolex, it could also be liberated into the cystic cavity by degeneration of protoscoleces and parenchymal cells of the brood capsule wall. Antigen B was found mainly in the distal cytoplasm and perinuclear cytoplasm of the tegument anterior to the suckers. It is apparently secreted to the outside and was present in the brood capsule contents; it adheres to the anterior surface and the posterior periodic acid-Schiff (PAS)-positive glycocalyx of the protoscolex and to the inner surface of the brood capsule wall. The protoscolex tegument posterior to the suckers was negative. The parenchyma cells of the protoscolex and brood capsule wall were also positive although the intensity of the reaction product was variable.

Animals↗
PubMed1977

Strain differences in Echinococcus granulosus, with special reference to the status of equine hydatidosis in the United Kingdom.

The genetics of speciation in the genus Echinococcus are briefly discussed. As the organism is a hermaphrodite and multiplies asexually in the larval stage, the genetic mechanism for the ready production of new strains is inherent in the life-cycle. Some biological, biochemical and nutritional differences between the horse and sheep strains are examined. The sheep strain may be grown to sexual maturity, in vitro, in a diphasic system; the horse strain fails to grow in such a system. Differences have also been demonstrated between the soluble proteins of the two strains. The sheep strain is infective to man but, probably, non-infective to horses. The horse strain (which is now the major strain in the U.K and Ireland) appears to be poorly infective to sheep and may prove to be non-infective to man. The importance of determining the basic characteristics of other strains of E. granulosus are also stressed.

Animals↗
PubMed1977

Studies on the mechanism of lysis of Echinococcus granulosus protoscoleces incubated in normal serum.

Brood capsules were obtained from freshly collected cysts of equine and ovine strains of Echinococcus granulosus. Protoscoleces were freed from brood capsules either by mechanical disruption or pepsin-HCI digestion. Preparations of protoscoleces studied included: mechanically released protoscoleces without further treatment, or incubated either in HCI pH 2.0 or in evaginating solution (containing Na taurocholate) for 24 h; pepsin-HCI released protoscoleces without further treatment or incubated in evaginating solution for 24 h or 7 days. Half of each preparation of ovine protoscoleces was fixed in absolute methanol. All fresh preparations of protoscoleces lysed rapidly when incubated in normal human serum. Studies with a fluorescein isothiocyanate (FITC) labelled sheep anti-human C3 antiserum revealed the presence of C3 on the surface of lysing protoscoleces. Antibody could not be detected on the surface of any of the preparations of fresh or methanol-fixed protoscoleces using direct or indirect fluorescent antibody tests suggesting that the classical pathway of complement activation was not involved in the lytic process. Strong evidence for lysis by the alternate pathway of complement activation was the lysis of protoscoleces which had been treated with pepsin-HCI and lysis of protoscoleces in guinea-pig serum deficient in C4 component of complement.

Animals↗
PubMed1977

Immunohistological localisation of two hydatid antigens (antigen 5 and antigen b) in the cyst wall, brood capsules and protoscoleces of Echinococcus granulosus (ovine and equine) and E. multilocularis using immunoperoxidase methods.

Cyst wall, brood capsules and evaginated protoscoleces of E. granulosus (ovine and equine) and E. multilocularis were fixed in 10% formol-saline, embedded in paraffin and cut at 8 micrometer. Specific rabbit antisera to antigen 5 and antigen B of hydatid cyst fluid were used with immunoperoxidase methods to localise the antigens in the histological sections. Antigen 5 was found in all parasites and was associated with cells of the subtegumental area of the protoscolex, the brood capsule wall and the germinal membrane. The labelled antigen appeared as distinct granules in all areas. It is suggested that antigen 5 may be synthesised in all of these sites and that a source of the antigen in cyst fluid may be the germinal and brood capsule membranes. The laminated membranes of E. granulosus (ovine and equine) were, except for the superficial layers, free from antigen 5. Antigen B was present in all parasites. It was distributed diffusely throughout the laminated membrane, germinal membrane and brood capsule wall. There were areas of densely labelled antigen B on the surface of the distal cytoplasm of the protoscolex tegument and the surface of calcareous corpuscles. The distribution of antigen B in relation to PAS positive material and possible complement activating substances is discussed. The laminated membrane of E. granulosus was apparently more permeable to antigen B than to antigen 5. It is suggested that differences in the diffusion of these antigens through the laminated membranes of hydatid cysts in the same or different host species may account for variable serological responses during infection.

Animals↗
PubMed1977

Hydatidosis: a global problem of increasing importance.

This review of recent literature reporting the occurrence of hydatid disease due to Echinococcus granulosus and E. multilocularis throughout the world emphasizes the global nature of the problem and the threat of its spread into those countries currently free from it. Attention is drawn to the urgent need for measures to prevent the importation of infected livestock and this would require the development of techniques for pre-mortem diagnosis and differentiation of hydatidosis and cysticercosis of animals. There must also be increased awareness of the possible occurrence of biological strains of the parasite which may be of greater or lower infectivity for man. In the absence of information on infectivity, studies concerning the prevalence of the disease may be meaningless.

Africa↗
PubMed1975

In vitro suppression of segmentation in Echinococcus multilocularis with morphological transformation of protoscoleces into monozoic adults.

When protoscoleces of Echinococcus multilocularis were cultured in vitro, under axenic conditions in either monophasic or diphasic media, segmentation was suppressed in most organisms, some 70-80% of which developed into unsegmented, monozoic forms with a complete set of sexually mature male and female genitalia. The most striking feature of monozoic worms was the large lateral swelling produced by the cirrus sac the effect being to produce organisms with an unusual asymmetric shape. Worms which did not become monozoic either (a) underwent some somatic growth, developed two sets of genitalia and became 'pseudo-segmented', i.e. with the inter-proglottid membranes absent or poorly defined, or (b) became vesicular or abnormal. The mechanisms which could be involved in the suppression of somatic growth and the induction of the monozoic condition, are examined in terms of cell lineage. The possible significance of these results in understanding the evolution of the cestodes is discussed.

Animals↗