bluuebunny/crossref_metadata_2025 huggingface dataset:
The migration of juvenile forms of Fasciola hepatica L. through the wall of the intestines in the mouse, with some observations on food and feeding
Authors: Dawes Ben
Published: June 2009

An attempt has been made to study the movements and feeding habits of juvenile forms of Fasciola hepatica as they pass through the wall of the host's intestines during the first 24 hr. of experimental infections in the mouse. Metacercarial cysts were fed to mice in large numbers (100–500) and the flukes were examined by means of sections during excystment and as free flukes and flukes making their way through various tissues. Excystment is regarded as essentially a feeding operation, the young fluke breaking through the fibrous inner cyst by the physical action of the ventral sucker in weakening the wall and the oral sucker in the actual breakthrough. Free forms were found in sections of infected intestines both in the lumen and lying between the villi, and penetrating forms were located inside the villi, in the submucosa and passing through the muscular layers and the serosa. A great deal of evidence was accumulated which indicates that the young fluke is able to break down epithelia, connective tissue and unstriped muscle fibrils and to feed upon the resultant products, thus proving itself to be a tissue feeder in the broadest sense of the term. The fluke's passage through the intestinal wall is by a devious route, tangential to the mucosa for some distance and then usually diagonally through the muscular layers, following the direction in which the circular muscle cells are oriented but cutting across the longitudinal muscle cells. This is probably due to the angle which the rim of the oral sucker makes with the longitudinal axis of the body, and it is a modification of the browsing habit which is seen when the feeding fluke lies on a plane surface. The tissue feeding proclivities of young flukes were also displayed in instances of penetration into lymph nodes and adipose tissue. These evidences support the opinion previously expressed by the writer that flukes migrating through the hepatic parenchyma, which are merely forms a little older and larger than the forms studied in the present researches, cannot be regarded as blood-feeders in the strict sense of the term but must also be regarded as tissue feeders. Attention is directed to the fact that very few digenetic trematodes have caecal outgrowths and that Fasciola and Fascioloides stand apart from all other genera in having dendritic outgrowths of the intestines. It is remarked also that the development of the ramifications of the intestines in Fasciola hepatica occurs during the first month, and largely during the second week, of juvenile life when the young flukes are eating their way through the hepatic parenchyma. During a few days the ramifications of the caeca develop to a greater extent than occurs during the entire lifespan of all other digenetic trematodes, with the exception of Fascioloides magna.
The formation, structure and histochemistry of the metacercarial cyst of three species of digenetic trematodes
Authors: Pike Alan W. , Erasmus D. A.
Published: June 2009

Cercariae of Psilotrema oligoon and Notocotylus attenuatus encyst free to form multilayered, hemispherical cysts. The former consists of four layers in which the innermost (layer 4) is divided into two, chemically and structurally different, areas. Cysts of the latter have three layers in which the innermost (layer 3) is again divided into two chemically different parts. A third cyst, produced by the encystment of Cercaria tarda in the tissues of Limnophilus flavicornis, is spherical and contains three layers (of which the outermost was not studied).

All of the cysts studied contain a high proportion of protein, which in some layers occurs combined with carbohydrates. In both free-encysting species the two outer layers are produced by expansion of a non-cellular layer covering the integument and the innermost layer is produced by secretion of bâtonnets from a layer of cells lying beneath the body wall. Cysts of P. oligoon are divided into two separate parts, each having two layers, whereas those of N. attenuates consist of a single three-layered wall. The innermost layer in both consists of a protein with disulphide and sulphydryl linkages, and in the cyst of P. oligoon it has a circular ventral area containing carbohydrates. A similar carbohydrate-containing area occurs in the innermost layer of the cyst of N. attenuatus but as a ventro-lateral ring of material. The cyst of Cercaria tarda is also predominantly proteinaceous and stains intensely for RNA.
Neuropeptides in platyhelminths
Authors: Fairweather I. , Halton D. W.
Published: June 2009

The neuropeptide story began in 1928 with the description by Ernst Scharrer of gland-like nerve cells in the hypothalamus of the minnow,Phoxinus laevis.Because these nerve cells were overwhelmingly specialized for secretory activity, overshadowing other neuronal properties, Scharrer termed them ‘neurosecretory neurons’. What was even more remarkable about the cells was that their products were released into the bloodstream to act as hormones, specifically neurohormones. Neurosecretory cells were identified largely on morphological grounds. That is, they could be stained with special techniques, such as chrome-haematoxylin and paraldehyde-fuchsin, although the techniques are far from specific, staining non-neurosecretory cells as well. However, the basis for the ‘special’ neurosecretory techniques is the demonstration of sulphur-containing proteins – so they are indicative of peptide-producing neurones. An alternative characteristic of neurosecretory cells is the presence of large (> 100 nm), dense-cored vesicles at the electron microscope level; these are the so-called elementary granules of neurosecretion, or ENGs. However, implicit in the concept of neurosecretion is that the prime function of the neurosecretory cell is in endocrine regulation, exerting a hormone-like control over some aspect of the organism's metabolism, by controlling endocrine glands and other effector organs. To satisfy this criterion, evidence had to be obtained of cycles of secretory activity within the cell that could be correlated with a change in the physiological condition of the organism.
Studies on the protein metabolism of cestodes 2. Effect of free dietary amino acid supplements on the growth of Hymenolepis diminuta
Authors: Mettrick D. F.
Published: June 2009

The dry weight, nitrogen content, and total carbohydrate content of Hymenolepis diminuta were studied after a period of 15 days growth in rats, maintained on different diets. The special diets were fed during the last 7 days of this period.

Using equal iso-molecular quantities, seven amino acids, representing the different classes of neutral amino acids, acidic amino acids and basic amino acids, have been screened for their effect on worm growth when added as free dietary supplement to the different diets. All of them, to a greater or lesser extent, had significant effects on worm growth.

The award of a research grant by the Standing Advisory Committee for Medical Research in the British Caribbean is gratefully acknowledged. I am also indebted to Professors J. C. Waterlow and C. von Holt for the loan of equipment in order to carry out the carbohydrate and nitrogen determinations, to Professor I. M. Good-body for his continued interest and support, and to the Rippel Foundation for research facilities.
The occurrence of Diplozoon paradoxum Nordmann, 1832 (Trematoda: Monogenea) in certain waters of northern England and its distribution on the gills of certain Cyprinidae
Authors: Wiles Michael
Published: June 2009

The monogenean Diplozoon paradoxum occurs on Abramis brama, Gobio gobio, Phoxinus phoxinus and Rutilus rutilus in northern England. In any one area, the infection is present in some waters but absent in others and predominates in rivers rather than in ponds or reservoirs.

D. paradoxum is randomly distributed on the gills, sides of the gill apparatus, hemibranchs and surfaces of primary lamellae of G. gobio, P. phoxinus and R. rutilus (except for P. phoxinus where inner hemibranchs carry more worms), but prevails on median sectors of the gills of these hosts. In A. brama the parasite is more numerous on certain gills, on the right side of the gill apparatus, and on the inner hemibranchs, but is randomly disposed on primary lamellar surfaces and along the gills. Except on G. gobio attachment is predominantly to two primary lamellae rather than one. This may reduce dislodging effects of the gill ventilating current by leaving portions of the lamellar surfaces unoccupied and allowing unimpeded flow in these regions.

This work was conducted during tenure of a Science Research Council Research Studentship. Research facilities in the Department of Zoology, University of Leeds, were kindly provided by Professor J. M. Dodd. Other facilities in the Biological Station, St John's, Newfoundland, were provided by the Director, Dr W. Templeman. Statistical advice offered by Dr E. Broadhead, Department of Zoology, and Professor C. L. Oakley, Department of Bacteriology, both of the University of Leeds, is gratefully acknowledged. I am indebted to Dr R. Wynne Owen, Department of Zoology, for constant advice and encouragement and for critical reading of the manuscript.
Acanthobothrium quadripartitumsp.nov. (Cestoda: Tetraphyllidea) fromRaja naevusin the North Sea and English Channel
Authors: Williams H. Harford
Published: June 2009

Acanthobothrium quadripartitumsp.nov., from the intestine ofRaja naevusin the North Sea and English Channel is described and figured. In adult morphology it resemblesA. brevissimeLinton, 1908, more closely than any other known species of the genus.A. quadripartitumis one of the smallest known tapeworms and occurs in numbers of up to 13000 in one intestine. Preliminary observations indicate that it has little damaging effect on the epithelial cells of the host's mucosa.

I am indebted to Professor V. C. Wynne-Edwards for providing excellent research facilities and to the Director and Staff, in particular Dr B. B. Rae, Dr Z. Kabata and Mr Stuart Pirie, Marine Laboratory, Aberdeen, for laboratory space and material.
Naturally occurring antibodies to the cuticle of nematodes
Authors: Hogarth-Scott R. S.
Published: June 2009

Studies based on the mixed antiglobulin reaction have shown that γ-globulin is adsorbed from normal human sera by the cuticle of parasitic nematodes. Using antiglobulins specific for IgA, IgM and IgG, it was possible to demonstrate uptake to titres of 4, 64 and 128, respectively. Adsorption continued for at least 24 h, and the responsible immunoglobulins could be absorbed from the sera by nematode preparations.

A comparison of normal human sera with sera from cases of ascariasis and visceral larva migrans revealed that there was no significant difference between the titre of anti-cuticular immunoglobulins in normal sera or sera from helmin-thiases. It is suggested that these immunoglobulins adsorbed by the nematode cuticle represent cross-reacting, naturally occurring antibodies.

I am sincerely grateful to Professor R. R. A. Coombs, F.R.S., for his help, advice and encouragement, and to Mr M. J. Eburne for splendid technical assistance.
Schistosoma mansoni: adult males and females differentially express antigens encoded by repetitive genomic DNA
Authors: Smith A. L. , Huggins M. C. , Havercroft J. C.
Published: June 2009

Two repetitive DNA sequences have been characterized from Schistosoma mansoni which were transcribed into mRNAs and translated to give two families of cross-reactive proteins. One DNA element, which was present as a 230 bp Pst I fragment was arranged in tandem arrays of at least 17 copies in the genome. The second element, which could be localized to a 1800 bp Pst I fragment, was dispersed in the genome. The 1800 bp repeat was found on the mRNA encoding the 45 kDa polypeptide precursor of a potential surface antigen. This precursor was post-translationally modified to give a 50 kDa antigen (Sm50) which was expressed from the cercaria to the adult worm and in the egg. However, a proportion of this antigen was differentially modified in females and eggs to give a 60 kDa form. Two copies of the 230 bp repeat and one copy of the 1800 bp repeat were found on a second cDNA clone. The antiserum raised against the fusion protein of this clone recognized a family of cross-reactive proteins ranging from 14 to 70 kDa in size. The members of this family were also differentially expressed between the sexes. Consequently, two families of antigens have been identified which were both encoded by repetitive DNA elements and whose members were both differentially expressed in adult male and female worms.
Cheyletiella parasitivorax (Acarina: Trombidoidea) as a parasitic mite in Britain
Authors: Beesley W. N.
Published: June 2009

Since its discovery in France by Mégnin (1878), Cheyletiella parasitivorax has been found in many countries—on rabbits (Oudemans, 1906; Pillars, 1925; Ford, 1944; Mykytowycz, 1957a; Womersley, 1941), on the dog (Humphreys, 1958), fox (Kuscher, 1940), cat (Niggli & Teuscher, 1959; Davies, 1941), man (Olsen & Roth, 1947) and even in phoretic association with fleas (Cooper, 1946). Hirst (1917) was the first to find the species in Britain and there have been several more recent records from this country.
The effect of sulphaquinoxaline and amprolium on the life cycle of Eimeria adenoeides Moore and Brown, 1951, in turkey poults
Authors: Warren E. W. , Ball S. J.
Published: June 2009

Sulphaquinoxaline fed at 0·0125%, w/w, in the food principally affects the development of the second generation schizonts of Eimeria adenoeides in turkey poults. Amprolium, at the same concentration, acts on the first generation. Both drugs appear to exert some effect on gametogony. The activity of sulphaquinoxaline against this species is inhibited by p-aminobenzoic acid, and the activity of amprolium by thiamine.

We are grateful to Mrs B. M. Mitchell and Miss C. Hitchcock for technical assistance and to Mr A. D. Speed for the histological preparations.
The effects of computer-controlled shadow stimuli on the success of cercarial transmission by Cryptocotyle lingua (Digenea: Heterophyidae)
Authors: Rea J. G. , Irwin S. W. B.
Published: June 2009

Pectoral fins from juvenile rainbow trout (Oncorhynchus mykiss) were used in a bioassay, the object of which was to quantify the effect of simulated shadow stimuli on the transmission success of the cercariae. For a period of 60 min, parasites and fins were exposed to a sequence of computer-controlled shadow stimuli, continuous light or total darkness, and subsequently the number of infections was counted. Trials were conducted with cercariae 1, 12 and 24 h old. Within the constraints of the experimental procedure, shadows were found to increase significantly the number of infections achieved by the 12-h-old parasites. As the cercariae aged, their ability to infect host tissue declined. The relevance of these results to transmission in the natural environment is discussed.
Population genetics of Trypanosoma brucei in Central Africa: taxonomic and epidemiological significance
Authors: Truc P. , Tibayrenc M.
Published: June 2009

In order to estimate the value of population genetics for both the taxonomy of trypanosomes belonging to the species Trypanosoma brucei and a better understanding of Human African Trypanosomiasis (HAT), we undertook a cellulose acetate electrophoresis isoenzyme study involving 55 stocks isolated from man and animals in Congo, Zaire and Cameroun. Out of the 24 loci surveyed, 15 exhibited variability, which made it possible to delimit 23 zymodemes, divided into 2 groups. The first group equated to the classical subspecies Trypanosoma brucei gambiense, while the second corresponded to the classical subspecies Trypanosoma brucei brucei. These results broadly agree with the current taxonomy, and are corroborated by RFLP analysis of kDNA. Statistical analysis indicates a basically clonal reproduction system of the trypanosomes in the area studied; the zymodemes are equivalent to natural clones (or a family of closely related clones), stable in space and time. Epidemiological hypotheses are proposed according to the geographic distribution of the clones in this area.
Leishmaniasis epidemiology: all down to the DNA
Authors: Blackwell J. M.
Published: June 2009

Application of quantitative methods to the study of leishmaniasis epidemiology has allowed Dye (1992) to pinpoint important biological parameters which, if they could be accurately measured in the field, would contribute most to our knowledge of the spread of disease and key targets for control. Three areas in which laboratory-based research could impact most on leishmaniasis epidemiology were highlighted by Dye (1992): (i) the development of accurate diagnostic tools which can distinguish between current and past infection; (ii) to determine the underlying molecular/genetic basis to virulence polymorphisms in the parasite and study these in the context of field epidemiological studies; and (iii) to provide the molecular tools to measure genetic variation in resistance to infection in humans and in reservoir hosts of disease. This paper describes current progress in attaining these goals, highlighting first the work on isolation and field application of genomic and kDNA probes for species-specific diagnosis, and the development of PCR-based assays which can be performed under field conditions. At a more preliminary stage, studies are described in which variability in the major molecular determinants of virulence (lipophosphoglycan, GP63, and members of the HSP7O family of stress proteins) identified through studies of laboratory models of infection, is being measured in primary field isolates ofLeishmania peruviana. To complete the picture, current progress in identifying and cloning the genes which control host resistance to leishmanial infection is described, along with field studies of multicase families of human disease in which linkage analysis using marker genes from the chromosomal regions bearing these genes can be used to find evidence for their role in determining disease phenotypes in man. The leishmaniasis epidemiology will be all down to the DNA. projected view from these studies is that the future of leishmaniasis epidemiology will be all down to the DNA.
Viruses, chemotherapy and immunity
Authors: Koziel M. J. , Walker B. D.
Published: June 2009

An increasing number of antiviral agents are presently in various stages of development and testing, and an increasing number have recently been licensed for use in humans. These drugs have been used extensively to treat viral infections in immunocompromised individuals, and these studies indicate that for many antiviral agents the response to therapy is highly dependent on the integrity of the underlying host immune response. In particular, the response to zidovudine, acyclovir and ganciclovir in persons with HIV-1 infection is highly dependent upon CD4 number, which can be considered a surrogate marker for the state of host immune function in these subjects. Responses to interferons likewise can be shown to depend on the host immune response, with responses due to both direct antiviral effects of this agent as well as immunomodulatory effects mediated through interferon-induced upregulation of HLA molecule expression.
Diarrhoeal disease in early childhood: experiences from Sierra Leone
Authors: Hodges M.
Published: June 2009

In the Freetown area of Sierra Leone, the proportion of children under five years of age dying from diarrhoea-associated conditions has decreased since the 1970s from 4% to 3%. This reduction relates to children between 12 months and 5 years; deaths associated with diarrhoeal disease in infancy do not appear to have decreased significantly. Currently, 2% of children die in infancy and a further 1% before their fifth birthday from diarrhoeal diseases. Thirty-one percent of short-term growth-faltering in children under five years of age is attributed to diarrhoeal disease. Reasons for improvement in mortality may include the implementation of a National Diarrhoeal Diseases Control Programme and improved case management; some 55% of cases of acute diarrhoea in Freetown now receive oral rehydration therapy. Morbidity and mortality are influenced by the seasons. This is likely to be related to the fact that the nutritional status of children shows a significant deterioration in the early rainy season. At this time incidence of severe diarrhoea warranting hospital admission and diarrhoea mortality rates in hospital and at a Rehydration Center increased significantly. On the other hand, the presentation of dehydrating diarrhoea is greatest in the driest months of the year. Progress in the rural areas of Sierra Leone may not have been so evident although 60% of the population now have access to primary health units within 4 miles and efforts to increase host resistance have included the measles immunization programme which currently protects 60% of under-fives nation-wide. Efforts to reduce the transmission of pathogens have meant increasing access to safe water to 22% and to improved sanitation to 35% in rural areas of Sierra Leone. The sustainable prevention and control of diarrhoeal diseases in developing countries depends also upon increasing levels of adult literacy especially of women.
Summary and recommendations
Authors: Crompton D. W. T. , Savioli L.
Published: June 2009

According to Carpenter (1993), the first problem for nutritional science, to identify the chemicals required in a diet to support human growth and maintenance, has been solved. Enough information has been amassed from the study of many populations to enable nutritionists to offer safe recommendations about daily intakes of energy and nutrients for all stages of the human life cycle (see reviews by Nesheim and by Solomons, this volume). Adoption of these recommendations would generally correct deficiency diseases and would reduce the incidence of health complications which are linked to excessive intakes of fat, sodium, alcohol and other substances. Carpenter also drew attention to malnutrition, the solution of which he believed to have become largely political and economic although the fact remains that very many people still do not receive or grow enough food. In the context of this volume, Carpenter's most interesting point was his view that our understanding of the complex relationship between nutrition and disease was still at an early stage.
Density-dependent acquired resistance to ticks in natural hosts, independent of concurrent infection with Babesia microti
Authors: Randolph S. E.
Published: June 2009

The question of whether the known immunosuppressive effects of Babesia microti may disrupt the development of acquired resistance to its tick vector, Ixodes trianguliceps, in natural rodent hosts (Clethrionomys glareolus), and thus enhance thedisease transmission potential, is addressed experimentally. The results show for the first time that natural hosts can acquire resistance to ticks; that this acquired resistance is manifested chiefly by a strongly density-dependent reduction in the percentage of attached larvae that engorge; that the density dependence is quantitatively similar whether the host receives occasional large tick challenges or frequent low infestations; but that infection with B. microti does not disrupt this pattern of acquired resistance. Of two important natural host species, Apodemus sylvaticus can support repeated infestations of I. trianguliceps, but is a poor host to B. microti, while C. glareolus develops acquired resistance to the tickvector, but supports much higher-level, longer-lasting B. microti infections.
Effect of metacestodes of Hymenolepis diminuta on storage and circulating carbohydrates in the intermediate host, Tenebrio molitor
Authors: Kearns J. Y. , Hurd H. , Pullin A. S.
Published: June 2009

The metamorphosis of oncospheres of the rat tapeworm, Hymenolepis diminuta, to mature metacestodes induces several pathophysiological effects in the intermediate host, Tenebrio molitor (Coleoptera). Previous investigations have failed to elucidate the mechanism responsible for changes in the host reproductive physiology and behaviour. This work forms part of an assessment of the degree to which nutrient resource management may be involved in these interactions. We report that developing metacestodes exert a pronounced effect upon host carbohydrate reserves and also alter circulating carbohydrate titres at some stages post-infection. Biochemical studies of fat body glycogen demonstrated a significant depletion of reserves as early as 3 days post-infection in males and 5 days post-infection in females. Gas chromatography revealed trehalose to be the predominant haemolymph carbohydrate, titres being significantly elevated in male beetles 5 and 9 days post-infection and in females 12 days post-infection. Metacestodes had no effect on glucose concentrations in male or female beetles.
Immune responses of Texel sheep to excretory/secretory products of adult Haemonchus contortus
Authors: Schallig H. D. F. H. , van Leeuwen M. A. W. , Hendrikx W. M. L.
Published: June 2009

The excretory/secretory (E/S) products of adult Haemonchus contortus comprise of at least 15 polypeptides with molecular weights ranging from 10 to > 100 kDa. These E/S products induce an immune response in infected Texel sheep, as demonstrated by specific IgGI levels and a significant lymphocyte proliferation index. Moreover, immunoblotting analysis revealed that sera of primary H. contortus-infected sheep specifically recognize a 24 kDa E/S product. In addition, sera of challenged sheep react strongly with a 15 kDa E/S product. The other E/S products of H. contortus showed immunoreactivity with serum samples of Haemonchus-infected sheep as well as with samples of sheep harbouring other trichostrongylid infections. These cross-reacting epitopes are the main cause of the lack of specificity of an E/S material- based ELISA. This ELISA can differentiate Haemonchus infections from Nematodirus battus infections, but not from Ostertagia circumcincta or Trichostrongylus colubriformis infections.
A 69 kDa immunodominant antigen ofTrypanosoma (Nannomonas) congolenseis homologous to immunoglobulin heavy chain binding protein (BiP)
Authors: Boulangé A. , Authié E.
Published: June 2009

An immunodominant antigen inTrypanosoma congolense-infected cattle is a 69 kDa protein which is conserved among species and developmental stages of African trypanosomes. Immunoscreening of a cDNA expression library identified a 2·35 kbp clone which contains a complete open reading frame encoding a protein of 653 amino acids with a predicted molecular mass of 71 kDa. Protein sequence analyses revealed 45–65% identity with hsp70s from a broad range of organisms, the highest homology being with the mammalian BiP (immunoglobulin heavy chain binding protein). The 69 kDa trypanosome protein shares with other BiP-related molecules two characteristics that are associated with their localization in the endoplasmic reticulum and their function as chaperonins, i.e. a hydrophobic N-terminal signal sequence and a conserved C-terminal tetrapeptide (X)DEL. Divergence between the 69 kDa antigen and other BiP-homologues occurs in the C-terminal region. This may be responsible for the high immunogenicity of the trypanosome protein. The gene for the 69 kDa antigen appears to be present as a cluster of several copies which are not organized in tandem repeats. It is expressed in all developmental stages ofT. congolense, but the specific mRNA levels are higher in metacyclics than in other stages.
Proteinase activity in the plerocercoid of Proteocephalus ambloplitis (Cestoda)
Authors: Polzer M. , Overstreet R. M. , Taraschewski H.
Published: June 2009

Host invasion and tissue migration of several helminths have been linked to expression and release of parasite-derived proteinases. The plerocercoid of the cestode Proteocephalus ambloplitis can migrate into the visceral organs or, in the case of bass, from them into the intestinal tract of the same individual fish. It does this within a few hours, aided by secretion of a substance from its apical gland. Proteinase activity in this plerocercoid, obtained from the host liver, was defined by pH optimum, by substrate and inhibitor specificity, and by electrophoretic and chromatographic techniques. Homogenates of plerocercoid contained a metalloproteinase exhibiting a molecular weight of 30000 determined by gelatin substrate gel electrophoresis. Peak activity of this proteolytic enzyme in gel filtration fractions when azocoll was used as substrate then corresponded to a molecular weight of 31500. The proteinase showed collagenolytic, haemoglobinolytic and slight elastinolytic activity, and it had a pH optimum at 9·0. Enzyme activity could be inhibited by various chelating agents. The metalloproteinase identified in this study constitutes the only enzyme class present in this larval stage of P. ambloplitis. We suggest that the plerocercoid's metalloproteinase is the substance secreted from the apical organ, necessary for the previously recognized tissue migration phase. This enzyme might also have a nutritional function.
Modification of macrophage – T cell interaction during infection of mice with Mesocestoides corti (Cestoda)
Authors: Kadian S. K. , Dixon J. B. , Green J. R. , Carter S.D. , Jenkins P.
Published: June 2009

Peritoneal macrophages from Mesocestoides corti-infected mice showed a marked and progressive loss of ability to act as accessory cells for syngeneic Con A-stimulated mesenteric lymph node lymphocytes. The same effect on the macrophages could be induced by intraperitoneal injection of M. corti culture supernatant, despite a concurrent increase in numbers of peritoneal adhesive macrophages. The findings are used to compare and contrast the known immunomodulatory effects of M. corti and taeniid metacestodes, the latter differing chiefly in their potential for modifying T-cell as well as macrophage behaviour.
In vitropolarization of carp leucocytes in response to the blood flukeSanguinicola inermisPlehn, 1905 (Trematoda: Sanguinicolidae)
Authors: Richards D. T. , Hoole D. , Lewis J. W. , Ewens E. , Arme C.
Published: June 2009

Sumary

Anin vitroassay was used to determine the effects ofSanguinicola inermisadults and cercariae on the polarization responses of pronephric leucocytes of carp. Leucocytes were isolated and exposed to live adult flukes or cercariae for up to 48 h. Differences in polarization responses were related to the presence of the parasite, the presence or absence of carp serum and the time of incubation. The mean proportions of cells exhibiting polarization in unstimulated controls ranged from 5 to 30% over the experimental period. Within 15 min of exposure to adults or cercariae, significant increases in mean polarization responses were observed of up to 75% and levels remained higher than control values for over 24 h. Overall, the presence of normal carp serum, either untreated or heat inactivated, did not enhance the polarization responses of leucocytes incubated with only cercariae or adults. However, between 0·25 and 3 h, the presence of carp serum with cercariae significantly enhanced polarization responses when compared with cells incubated with cercariae alone.
Spontaneous release of cysteine proteinases but not of pore-forming peptides by viableEntamoeba histolytica
Authors: Leippe M. , Sievertsen H. J. , Tannich E. , Horstmann R. D.
Published: June 2009

Invasive properties of pathogenicEntamoeba histolyticahave been postulated to depend on the secretion or release of cysteine proteinases and pore-forming peptides (amoebapores) by trophozoites. To establish whether such toxic molecules are released by viable trophozoites or upon cellular disintegration, amoebae were maintained in various culture media, and activities in supernatants were monitored over time in correlation to cellular integrity. By measuring the release of the cytoplasmic marker enzyme NADP+-alcohol dehydrogenase, it became apparent that release of amoebapore was accompanied by cellular disintegration. In contrast, considerable quantities of cysteine proteinases were found to be present in culture supernatants also when amoebae remained intact. Treatment of amoebae with concanavalin A, bacterial lipo-polysaccharides or the calcium ionophore A23187 did not result in amoebapore secretion suggesting that here target cell contact is required as an essential stimulus.
Hymenolepis diminutaandH. microstoma: uptake of cyclosporin A and drug binding to parasite cyclophilins
Authors: Roberts H. C. , Sternberg J. M. , Chappell L. H.
Published: June 2009

Cyclosporin A (CsA) acts as a powerful immunosuppressant through its binding to the cytosolic isomerase, cyclophilin (CyP), forming a complex which inhibits the phosphatase activity of calcineurin. The drug is also selectively anti-parasitic but its mode of action remains unknown. The mouse tapeworm,Hymenolepis microstomais sensitive to CsA, but the rat tapeworm,H. diminutais not susceptible either in rats, mice orin vitro. Using these two tapeworm models, the uptake and binding of CsA were examined in relation to parasite cyclophilins. Uptake and compartmentalization of the drug were markedly different in the two species:H. microstomatakes up more drug than doesH. diminutaand sequesters more drug into intracellular compartments. Characterization of cyclophilins using both CsA binding and isomerase activity assays reveals thatH. microstomapossesses two cyclophilin isoforms (Mr17700 and 21400) with isomerase activity that is inhibited by CsA. Using identical assays, we have been unable to demonstrate CsA-binding proteins or CsA-sensitive isomerase activity inH. diminuta. These data suggest that the anthelmintic action of CsA relates in some way to the presence and function of parasite cyclophilins.
The fine structure and function of the adult epidermis of two skin parasitic monogeneans, Entobdella soleae and Acanthocotyle elegans
Authors: Lyons Kathleen M.
Published: June 2009

Electron-microscope investigations on the outer layers of parasitic platyhel-minths have so far neglected the monogeneans and have been confined to the endoparasitic digeneans and cestodes (Braten, 1968; Burton, 1966; Charles & Orr, 1968; Erasmus, 1967; Lumsden, 1966; Morris & Threadgold, 1967; Race, Larsh, Esch & Martin, 1965; Rothman, 1968; Threadgold, 1965). For this reason the covering layer of monogeneans is still referred to as a ‘cuticle’ even though it is unlikely to be so since the surface of the endoparasitic platyhelminths has been shown to be a living cytoplasmic ‘epidermis’ (see Lee, 1966) which, as pointed out by Erasmus (1967) and Lumsden (1966), constitutes a metabolically active inter-face with host tissues and fluids. Two main considerations prompted the present investigations of the covering layer of monogeneans. First, it was hoped that a comparison of the covering layer of these ectoparasites with that of the digeneans and cestodes might help to define particular specializations of this layer associated specifically with the ectoparasitic or endoparasitic habit; secondly, because ectoparasitism can, in an evolutionary sense, be considered as a transitional state between a free-living and an endoparasitic existence (see Llewellyn, 1965), it was felt that this work on monogeneans could assist an understanding of the evolution of the platyhelminth outer layer.
Effects of larval Digenea on the free amino acid pool of Littorina littorea (L.)
Authors: Watts Stuart D. M.
Published: June 2009

Quantitative chromatographic analysis of the free amino acids of the head–foot muscle of uninfected and infected Littorina littorea indicates that there is specific variation in the physiological effects of parasitism. The total concentration of free amino acids in the host head–foot muscle showed an increase of 10·9% with infections of Cryptocotyle lingua rediae, a decrease of 12·7% with infections of Himasthla leptosoma rediae and a decrease of 57·5% with infections of Cercaria emasculans sporocysts. These effects probably depend on three main factors namely, the nature, size and mobility of the larvae of the three species concerned and the influence of these factors in determining the extent of any damage to the hepatopancreas of the host.

The larvae of C. lingua are probably less affected by the changes they induce in the free amino acid pool of the host than the larvae of H. leptosoma and Cercaria emasculans which induce changes equivalent to starvation.

This work was conducted during the tenure of a Science Research Council Studentship. I would like to thank Professor B. John and Mr A. R. Hockley for their helpful advice and criticism.
The ultrastructure of the epidermis of the redia and cercaria ofParorchis acanthus,Nicoll. A study by scanning and transmission electron-microscopy
Authors: Rees Gwendolen
Published: June 2009

Scanning electron-micrographs have shown the covering of microvilli on the surface of the redia ofParorchis acanthus.In the contracted state the elongated microvilli with bulbous extremities seen in the surface grooves may be the result of compression. The surface of the epidermis of the cercaria is smooth on a large area of the ventral surface and lattice-like with microvilli, laterally, anteriorly, dorsally and on the tail. The spines on the body can be withdrawn into sheaths by the contraction of muscle fibres inserted into the basement lamina below each spine.

I would like to express my sincere gratitude to Dr I. ap Gwynn of this department for preparing the scanning electron-micrographs and the School of Engineering Science, University of North Wales, Bangor for the use of their stereoscan. I should also like to thank Mr M. C. Bibby for technical assistance and Professor E. G. Gray and Dr W. Sinclair for assistance with the transmission electron-micrographs.
Epidemiological relationships of Trypanosoma brucei stocks from South East Uganda: evidence for different population structures in human infective and non-human infective isolates
Authors: Hide G. , Welburn S. C. , Tait A. , Maudlin I.
Published: June 2009

This study represents an analysis of trypanosome strains circulating within a confined location over a short period of time during a sleeping sickness epidemic in S.E. Uganda. A large number of Trypanosoma brucei isolates (88) were collected from a variety of hosts (man, cattle, pigs and tsetse) from villages within a 10 km radius and were analysed for variation in isoenzyme patterns, restriction fragment length polymorphism (RFLP) in repetitive DNA sequences and susceptibility to human serum. The human infective stocks form a clearly distinguishable population when compared with other stocks circulating in the domestic cattle reservoir. The data here support the occurrence of genetic exchange between the cattle stocks while an ‘epidemic’ population structure involving limited genetic exchange is a characteristic of the human infective stocks. Furthermore, it is shown that when both RFLP and isoenzyme analysis are carried out most stocks appear to have individual genotypes. Stocks which were formerly grouped as zymodemes are better considered as a collection of distinct individuals.
The structure and composition of the capsule of Trichinella spiralis in host muscle
Authors: Bruce R. G.
Published: June 2009

The results of ultrastructural studies and histochemical tests on the capsule of Trichinella spiralis are given. The capsule wall is shown to consist of two layers, an outer region of tightly compacted fibrils and an inner region of fibrils dispersed through matrix cytoplasm. Histochemical tests show the capsule wall to consist mainly of collagen and cystine. The appearance of the matrix, which is packed with mitochondria, rough endoplasmic reticulum, smooth reticulum and Golgi complexes, together with the histochemical reaction to the five enzymes tested, strongly suggests that the matrix is a region of high metabolic activity. Although there are several very large nuclei in the matrix there is no evidence of cell walls; consequently the matrix is a syncytium.

I wish to thank the A.R.C. for financial support while this work was carried out. I should also like to thank Dr D. L. Lee for his advice on many occasions and the late Professor Boyd of the Anatomy Department, University of Cambridge, for the use of the electron microscope in that Department.
Observations on the life-cycle of Toxocara mackerrasae
Authors: Warren E. G.
Published: June 2009

An analysis of natural infections of Toxocara mackerrasae in Rattus fuscipes trapped in rain forests in south-eastern Queensland is given and Hydromys chrysogaster is listed as a new host.

T. mackerrasae larvae in egg-infected mice are incapable of somatic migration but some complete development to the young adult stage can occur entirely within the alimentary tract. T. mackerrasae is capable, in low numbers, of developing to maturity in experimentally infected Rattus spp.

The work was financed by grants from the University of Queensland and the National Health and Medical Research Council of Australia. I wish to thank Professor J. F. A. Sprent for his criticisms and suggestions during the preparation of this text.
Diurnal movement ofHymenolepis diminutain the rat
Authors: Hopkins C. A.
Published: June 2009

Following a 2–5 ml meal containing 2 g (80%) glucose and 30 mg methionine administered by stomach tube at 09.00 h,H. diminutawas found to change its position in the rat's intestine. Usually while the stomach contained food ≤ 45 %, by weight, of the tapeworm lay in the posterior 40 % of the small intestine, after the stomach was empty the reverse was true.

The effect of hyperosmotic fluid entering the duodenum was determined by injecting, following laparotomy, varying amounts of 80 % glucose and 1 ml of varying concentrations. A volume ≤ 0-4 ml of 80 % led to the death and expulsion of worms within 7 h, and 1 ml of < 50 % glucose also killed the worms.

The expulsion of 15 % of the tapeworms from rats given 2–5 ml hypertonic meal by mouth was correlated with the failure of the stomach in some rats to regulate the stomach emptying. Worms in these rats were found from 4 h onwards in the caecum and large intestine, and by 9 h in the faeces.

That the movement of worms, other than those expelled, was not caused by a sub-lethal flux of hyperosmotic fluid was shown by feeding an iso-osmotic meal to rats; the worms moved to a more posterior position during the day, but none was expelled.

Single worm infections in rats kept on a normal feeding regime until 07.00 h and then starved throughout the day also showed a posterior migration. Using a method which involved the simultaneous cutting of the small intestine into 5 cm sections, it was possible to show that this movement involved the whole worm, the scolex moving from a mean position 10–15 cm to one 20–25 cm from the stomach, and the terminal proglottid moving from approximately 75 cm to 95 cm from the stomach.

Worms in Wistar rats responded similarly to those in SPF CFE (Sprague Dawleys) with the exception that there was some evidence that the stomach emptying of a hyperosmotic meal was better controlled and hence a smaller percentage of the worms were expelled.

The results are discussed in relation to diurnal changes in the level of the external site location stimulus which other workers have shown to exist by surgically transplantingH. diminutainto the ileum.

The enthusiastic assistance of Miss Helen Stallard, B.Sc., and Miss Patricia Grant is gratefully acknowledged, and financial support from the Medical Research Council, London (Grant No. G967/164/T).
Septata intestinalis frequently isolated from stool of AIDS patients with a new cultivation method
Authors: Van Gool T. , Canning E. U. , Gilis H. , Weerman M. A. Van Den Bergh , Schattenkerk J. K. M. Eeftinck , Dankert J.
Published: June 2009

Two species of microsporidia, Enterocytozoon bieneusi and Septata intestinalis have been reported as intestinal parasites of AIDS patients. In attempts to establish E. bieneusi in vitro, spores were concentrated from stool samples from 4 AIDS patients with biopsy-proven E. bieneusi infections. After sterilization of the concentrate in antibiotic solution, the spores were added to monolayers of RK13 cells grown on the membranes of Transwells. Cultures were established from 7 stool samples from the 4 patients but in every case the species established was S. intestinalis not E. bieneusi. On retrospective examination of the stools, a very small number of spores of a size comparable to that of S. intestinalis was found but this species was not detected in biopsies. Typical septate vacuoles containing Type I tubules were observed in vitro but in contrast to the original description, meronts were intravacuolar and sporogony was mainly disporoblastic. The cultivation system, used for the first time for microsporidia, revealed the presence of unsuspected S. intestinalis infections and indicates that this species may be much more common than hitherto suspected. S. intestinalis has not previously been cultured.
Proteinases of females of the phytoparasiteGlobodera pallida(potato cyst nematode)
Authors: Koritsas V. M. , Atkinson H. J.
Published: June 2009

Sensitive assays capable of detecting proteinases in single females of the phytoparasiteGlobodera pallidahave been developed and used to define the proteinase activity of young adult females. Digestion of the large subunit of the plant protein Rubisco established a pH optimum for the proteinase activity at pH 5·7. The activity was inhibited by the cysteine proteinase inhibitorsp-chloromercuribenzoic acid (PMBA) andp-chloromercurisulphonic acid (PMSA) and stimulated by both cysteine and dithiothreitol (DTT). It was moderately reduced by L-trans-epoxysuccinyl-leucylamido-(4- guanidino) butane (E64) but not by specific inhibitors of serine, aspartate or metallo-proteinases. The activity separated into 3 bands on a non-denaturing gel but only I proteinase of 62 kDa was recovered following a combination of anion-exchange chromatography and affinity chromatography using PMBA. The effect of inhibitors was similar to that reported previously for some of the cysteine proteinase activity recovered fromCaenorhabditis elegansbut is apparently not that for which the corresponding gene has been cloned in this nematode andHaemonchus contortus.The proteinase may have a major role in digestion of dietary protein and so offers an exciting target for future control of this important plant-parasitic nematode.
Immunocytochemical demonstration of peptidergic and serotoninergic components in the enteric nervous system of the roundworm,Ascaris suum(Nematoda, Ascaroidea)
Authors: Brownlee D. J. A. , Fairweather I. , Johnston C. F. , Shaw C.
Published: June 2009

The localization and distribution of neuropeptides and an indoleamine (serotonin or 5-hydroxytryptamine) in the enteric nervous system (ENS) of the pig roundworm,Ascaris suum, have been determined by the application of an indirect immunofluorescence technique in conjunction with confocal scanning laser microscopy. Whole-mount preparations of pharyngeal, intestinal and rectal regions were screened with antisera to 23 vertebrate peptides, 2 invertebrate peptides and serotonin (= 5-HT). Positive immunoreactivity (IR) was obtained with antisera to pancreatic polypeptide (PP), peptide YY (PYY), FMRFamide, gastrin and serotonin. The only IR observed in the ENS was that evident in the nerve supply to the pharynx and rectal region; no IR was associated with any region of the intestine. The most extensive patterns of IR occurred with antisera to PYY, FMRFamide and serotonin. In the pharyngeal component of the ENS, IR was evident in the lateral and dorsal longitudinal pharyngeal nerves, pharyngeal commissures, nerve plexus, and associated nerve cells and fibres. In contrast, the distribution of IR to the PP and gastrin antisera was more restricted and displayed a lower intensity of immunostaining. The other component of the ENS, the rectal enteric system, only yielded immunostaining to FMRFamide. The possible role of neuropeptides and serotonin in the nutritional biology of nematodes is discussed.