bluuebunny/crossref_metadata_2025_split huggingface dataset:
Schistosoma mansoni: differential cell death associated with in vitro culture and treatment with Astiban (Roche)
Authors: Shaw J. R. , Erasmus D. A. 
Published: June 2009

A simple technique for the maintenance in vitro of mature Schistosoma mansoni is described and critically assessed at the ultrastructural level. Females were cultured for 4–6 days with no apparent ultrastructural change, but after this period changes appeared in the cells of the ovary and vitelline gland. At a later stage (10–12 days) lipid bodies appeared in the parenchyma cells. These changes occurred in worms which were active, paired with males and were egg–laying. Thus the activity, pairing behaviour and egg–laying characteristics are not adequate to reveal the true morphological condition and presumably the physiological and biochemical status of cultured worms.This technique was used to study the effect of Astiban on females and the results were compared with worms treated in vivo. Astiban concentrations greater than 30 µg/ml killed worms within 7–20 h and acted non–selectively. Astiban at low concentrations (10µg/ml) during short–term culture (1–3 h) resulted in a selective action of the drug on maturing vitelline cells. Thus, although the degree of cell damage caused by drug treatment was more severe and occurred earlier than the effects observed in worms cultured in vitro without drugs, both treatments resulted in differential cell death.
Efficacy and cross-resistance studies on N, N′-bis (3,4 ditrifluoromethylphenyl) methylmalonamide, a novel anticoccidial agent
Authors: Panitz E. 
Published: June 2009

SUMMARYN, N′-bis (3,4 ditrifluoromethylphenyl) methylmalonamide (Sch18545) completely controlled a mild Eimeria necatrix infection at 50, 40 or 30 p.p.m. in the diet, and controlled E. tenella infections at 50 and 40 p.p.m. Slight oocyst passage was observed at each E. tenella treatment level with a marked increase at the 30 p.p.m. treatment level. Fifty p.p.m. were necessary to control E. acervulina infections; levels of 40 p.p.m. reduced E. acervulina oocyst production while 30 p.p.m. were ineffective. Evaluations of Sch 18545 using a mixed infection (Coccivac D®) further suggested that activity with this compound was weakest against E. acervulina. Weight gains decreased with increasing concentration of drug in the diet of treated, infected birds and thus the compound showed an insufficient safety margin to be of practical value. Sch 18545 administered at 35 p.p.m. in the diet was effective against amprolium, zoalene, aklomide or nicarbazin-resistant strains of E. tenella.
Studies on Eimeria dispersa Tyzzer 1929 in turkeys
Authors: Long P. L. , Millard B. J. 
Published: June 2009

SUMMARYEimeria dispersa was isolated from young, intensively housed turkeys in Britain. The parasite has morphological features in common with those of the original description. At least two generations of schizonts occur before gametogony and one or two more schizont generations are concurrent with gametogony. Four generations of schizonts are needed to account for the observed reproduction index of 2·08 × 106/oocyst inoculated. The first oocysts were discharged by 105 h and these sporulated. within 30 h at 30 °C. A single dose of between 1 × 102 and 1 × 106 oocysts depressed body weight gain of 3-week-old poults and 2 poults died 6 and 12 days after receiving 1 × 104 or 1 × 106 oocysts. A single dose of oocysts protected against a challenge inoculation given 14 days later. Poultsimmunized against E. dispersa were resistant to challenge with a strain of E. dispera obtained from the United States. Electrophoretic examination of 2 enzymes from both strains of E. dispersa showed that they had similar mobilities. Attempts to infect chickens, guinea-fowl and Japanese quail with E. dispersa were unsuccessful. The strain of E. dispersa isolated here is best referred to as E. dispersa (Briston).
The possible role of the frontal and sub-parietal gland systems of the pentastomidReighardia sternae(Diesing, 1864) in the evasion of the host immune response
Authors: Riley J. , James J. L. , Banaja A. A. 
Published: June 2009

SUMMARYThe frontal and sub-parietal glands of the pentastomidReighardia sternaeelaborate lamellate secretion which is poured on to the cuticle. The entire surface of the cuticle, including the mouth, hook pits and reproductive apertures, is coated with secretion. Electron microscope studies indicate that the glands are continuously active, which implies a turnover of surface membranes. The postulated function of these membranes is to protect certain vital areas of the host–parasite interface, notably the pores of ion-transporting cells, from the host immune response. The available evidence suggests that pentastomids do evoke a strong immune response but since most are long-lived they must circumvent it. We believe the surface membrane system to be instrumental in this. Studies on another pentastomid,Porocephalus crotaliin rats have shown that an immune response stimulated by a primary infection will kill subsequent infections and that the surface membranes are strongly immunogenic. Obvious parallels between this situation and that of schistosome infections in mammals are discussed. An alternative explanation of concomitant immunity is proposed.
Transplantation of adult Trichinella spiralis between hosts: worm survival and immunological characteristics of the host–parasite relationship
Authors: Kennedy M. W. , Wakelin D. , Wilson Margaret M. 
Published: June 2009

SUMMARYA technique for the transplantation of Trichinella spiralis worms directly into the host intestine is described. Infections established by the direct transfer of adult worms were essentially normal both in terms of their survival and reproduction and in their stimulation of, and susceptibility to, host immune responses. Worms transplanted from NIH mouse donors at intervals after infection had an equal ability to survive in the recipient, even when taken from the donor shortly before or during the process of worm expulsion, showing that expulsion does not require worms to be irreversibly damaged. It was noted, however, that after 7 days in the donor the ability of the worm to reproduce in the recipient was temporarily impaired.
Rejection ofEimeriaby foreign hosts
Authors: Long P. L. , Millard B. J. 
Published: June 2009

SUMMARYOocysts ofEimeria maximainoculated into guinea fowl do not develop. Infection occurs when intestinal mucosa or liver tissue from guinea fowl givenE. maximais transferred to susceptible chickens. By transferring material at different times after inoculation, it was shown that most of the stages are lost between 6 and 12 h and few, if any, survive to 48 h.Sporozoites ofE. tenellahad low infectivity after 48 h contactin vitrowith peritoneal macrophages from guinea fowls and turkeys. Sporozoites ofE. grenierifrom the guinea fowl appeared to be destroyed within macrophages taken from chickens.
Hybridization between Brugia patei, B. pahangi and sub-periodic B. malayi
Authors: Suswillo R. R. , Denham D. A. , McGreevy P. B. , Nelson G. S. 
Published: June 2009

SummaryVirgin females of Brugia malayi, B. pahangi and B. patei were mated with males of species other than their own to determine whether they would hybridize. Microfilariae were produced in all but one cross (that between B. pahangi males and B. malayi females). Hybrid infective larvae, produced in mosquitoes and inoculated intraperitoneally into jirds, grew to adults but these were unable to produce microfilariae because hybrid males did not produce spermatozoa. Hybrid females were fertile and produced microfilariae when crossed with males of their parental species.
Seasonal variation in the population dynamics ofCaryophyllaeus laticeps
Authors: Anderson R. M. 
Published: June 2009

SummaryThe biological parameters which generate seasonal fluctuations in the size of populations ofCaryophyllaeus laticepsare examined in detail. A mathematical model is formulated to describe the dynamics of the adult parasite within the fish hostAbramis brama, and the predictions of the model are compared with observed population data.The seasonality of parasite population size is shown to be caused by the combined effects of a temperature dependent mortality rate and fluctuations in host feeding activity, which controls the immigration rate of larval parasites. The observed overdispersed distribution of adult parasite numbers within the host population is shown to be generated by variability in feeding habits between individual members of the fish population.The theoretical population model is used as a framework for the investigation of, among other factors, the comparative influences of the immigration and death rates on the dynamics of the adult parasite, the future behaviour of the system under altered environmental conditions and the importance of chance effects in the dynamics of individual parasite populations within a single host.The stability of the dynamics of the complete life-cycle ofC. laticepsis discussed in relation to the inherent biological complexity of host/helminth parasite interactions.
Maintenance of Theileria parva parva infection in an endemic area of Kenya
Authors: Young A. S. , Leitch B. L. , Newson R. M. , Cunningham M. P. 
Published: June 2009

SUMMARYThe maintenance of Theileria parva parva infection in an endemic area of Kenya on the shore of Lake Victoria was studied in the field and laboratory. High prevalences of antibodies against T. parva and T. mutans and intra-erythrocytic piroplasms were detected in local zebu (Bos indicus) cattle. The mean infection rate of Theileria parasites in the tick, Rhipicephalus appendiculatus, in field collections was 1·1 %. Most of the infection was attributed to T. parva parva by application of field ticks to susceptible cattle. Five cattle, all about 1·5 years old, were purchased from local owners and transported to the laboratory. All five had oscillating antibody titres against T. parva and T. mutans and had patent theilerial infections during the subsequent 13 months. Uninfected R. appendiculatus nymphs were applied to cattle at 0, 3, 6, 9 and 13 months after transport to Muguga, and 18 out of 23 batches transmitted T. parva parva infection to cattle when 100 resultant R. appendiculatus adults were applied. Infection rates in the tick batches were usually low, with 1 salivary gland acinus infected/tick. Hence, a frequent carrier state of naturally infected cattle has been demonstrated for T. parva parva for the first time, and it is likely that this carrier state is of great importance in maintenance of T. parva parva infection in the field.
Evasion of macrophage microbicidal mechanisms by mature sporozoites ofPlasmodium yoelii yoelii
Authors: Smith Judith E. , Alexander James 
Published: June 2009

SUMMARYSporozoites ofPlasmodium yoelii yoeliiwere incubated for 40 min with BALB/c peritoneal macrophages in the presence of nitro-blue tetrazolium (NBT). While immature oocyst sporozoites triggered the macrophage respiratory burst, as visualized microscopically by the localized reduction of NBT to insoluble formazan, 97·6% of mature salivary gland sporozoites did not induce such a response. The macrophage oxidative response was also induced by 82·7% of heat-inactivated and 95·7% of trypsin-treated salivary gland sporozoites. The relationship of these results to the infectivity and immunogenicity of malarial sporozoites is discussed.
Immunization of calves againstSchistosoma bovisusing irradiated cercariae or schistosomula ofS. bovis
Authors: Bushara H. O. , Hussein M. F. , Saad A. M. , Taylor M. G. , Dargie J. D. , Marshall T. F. De C. , Nelson G. S. 
Published: June 2009

SummaryFourteen 9-month-old zebu calves were immunized with 10000 irradiatedSchistosoma bovisschistosomula given in 1–3 intramuscular or subcutaneous doses, and 4 more calves were immunized with 10000 irradiated cercariae administered percutaneously in a single dose. Eight weeks after the beginning of the experiment these calves, together with four non-immunized controls were challenged percutaneously with 10000 normalS. boviscercariae/calf. Comparative clinical, parasitological, pathological and pathophysiological observations subsequently revealed significant differences between the vaccinated and non-vaccinated calves. The vaccinated calves showed significantly higher growth rates, and a superior body composition as indicated by their lower total body water content. The beneficial effects of vaccination were also shown by significantly lower faecal egg outputs in the vaccinated calves and by their lower tissue egg and adult worm counts. The reduced tissue egg counts were also reflected in the milder histopathological changes seen in the vaccinated calves. The vaccinated calves had significantly higher packed cell and circulating red blood cell volumes than the challenged controls, longer red blood cell half lives, and somewhat lower blood volumes and rates of red blood cell synthesis. No untoward clinical effects that could be attributed to vaccination were recorded. These results indicate that zebu cattle can be effectively protected againstS. bovisby vaccination with irradiated organisms. We are now evaluating this type of vaccine in a field trial in an enzootic area in the Sudan.
Attenuation of Eimeria mivati ( = mitis) by selection for precocious development
Authors: McDonald V. , Ballingall S. 
Published: June 2009

SUMMARYBy selection for early development of oocysts during serial passage through chickens the pre-patent period of the Houghton (H) strain of Eimeria mivati ( = mitis) was reduced by over 20 h. The precocious parasite is less pathogenic than the H strain and has a reduced reproductive potential. Chicks inoculated with the precocious parasite were protected against challenge with the H strain. The pathogenicity, immunogenicity and reproduction of precocious E. mivati and an attenuated egg-adapted line of E. mivati were compared. Although the precocious parasite produced more oocysts than the egg-adapted parasite in chickens, neither parasite induced loss of weight and both were immunogenic.
Immunity to coccidiosis: stages of the life-cycle ofEimeria maximawhich induce, and are affected by, the response of the host
Authors: Rose M. Elaine , Hesketh Patricia 
Published: June 2009

SummaryAn attempt was made to determine the relative importance of the different life-cycle stages ofEimeria maximain the induction of immunity and also those stages most affected by the immune response of the host. In one experiment the life-cycle was controlled by chemotherapy but in all other experiments partial life-cycles were induced by transfers of infected mucosa between hosts.The results indicated that the second generation schizont stage is probably that most concerned in the induction of protective immunity and that sexual stages are most susceptible to immune inhibition. After initial inhibition in the immune host the earlier asexual stages were able to resume development when transferred to a susceptible host. The longer the period of exposure to the immune environment, the less able was the parasite to recover.
Studies on the induction of permeability inAscaris lumbricoideseggs
Authors: Barrett J. 
Published: June 2009

SummaryThe initial process in the hatching mechanism ofAscariseggs is the sudden onset of permeability in the previously impermeable ascaroside membrane. During this change the ascaroside membrane remains intact and no chemical changes can be detected. Using the molecular probe 1-anilino-8-naphthalene sulphonic acid no conformational changes were detected in the ascaroside membrane during the induction of permeability. It is suggested that either the permeability change is due to a very localized chemical or conformational change, not detectable by conventional analytical techniques, or the change is due to mechanical damage of the ascaroside membrane, brought about by the activity of the infective larva.
Parr Tate, 1901–1985
Authors: Crompton D. W. T. 
Published: June 2009

SUMMARYDuring my third year as an undergraduate reading Zoology at Cambridge, I found a relatively large parasite inside one of the Asellus aquaticus that had been allocated to me for the afternoon's practical work. After we had failed to identify even the group of animals to which it belonged, someone suggested that I should take my find to The Molteno Institute on the Downing Site. There I was ushered into Room 3 where I first met Dr Tate. After listening to my account he looked at my specimen and said, ‘Now just one second …’ in his rich Irish accent. As I later came to know, so much of his teaching or advice began with that highly characteristic phrase. He told me that I had found an acanthocephalan worm in its intermediate host, and when I returned some days later to tell him the results of my search of the literature, he suggested that I should work on the Acanthocephala under his supervision for the Ph.D. Degree after my graduation. I never regretted for one moment my decision to take up his offer. He maintained close contact with me, as he did with all his former research students, and the last letter I received from him was dated 16 September 1985, written just a few weeks before his death on 7 November 1985 in hospital in Cork. During the 24 years of our association I was never on Christian-name terms with him. He was always ‘Dr Tate’ or, when talking with equally close mutual associates like Donald Lee, David Molyneux, John Barrett, Vaughan Southgate or Roger Tatchell, we referred to him as ‘P.T.’. He had great integrity and fairness in all that he did and an ability of seeming to know exactly what you were thinking. These attributes, coupled with his extraordinarily wide parasitological knowledge, generated our respect. He also had a delightful sense of fun and even his sarcasm was kind and gentle. Our children loved him and his steady supply of sweets for those who visited him in Room 3 and the book tokens that came without fail every Christmas were expressions of his kindness.
Population dynamics in echinococcosis and cysticercosis: comparison of the response of Echinococcus granulosus, Taenia hydatigena and T. ovis to control
Authors: Gemmell M. A. , Lawson J. R. , Roberts M. G. , Kerin B. R. , Mason C. J. 
Published: June 2009

SUMMARYA comparative study has been made of the progress in the control of ovine echinococcosis caused by Echinococcus granulosus and the ovine cysticercoses caused by Taenia hydatigena and T. ovis in New Zealand. The methods of control included an educational and a dog-dosing programme. In the Styx field trial, the Otago/Southland Surveillance Programme and the national control programme, E. granulosus declined towards extinction. In contrast, this same control effort transformed the cysticercoses from hyper-endemic to endemic status with focal epidemics. In this unstable state, the density-dependent constraint was negligible and superinfection occurred.
Increased exposure of parasite antigens at the surface of adult male Schistosoma mansoni exposed to praziquantel in vitro
Authors: Harnett W. , Kusel J. R. 
Published: June 2009

SUMMARYPraziquantel is a broad-spectrum anthelmintic active against schistosome species which are major parasites of man. Two major effects on Schistosoma mansoni have been demonstrated; (i) spastic paralysis of the parasite musculature, possibly arising as a consequence of an influx of Ca2+ into the worm (Pax, Bennett & Fetterer, 1978; Coles, 1979) and (ii) vacuolation and degeneration of the worm tegument (Becker, Mehlhorn, Andrews, Thomas & Eckert, 1980). These events may contribute to the elimination of schistosomes in vivo, but this elimination may partly be dependent on the host immune response as infected T-cell-deprived mice are less able than immunologically intact animals to reduce their worm burdens following drug treatment (Doenhoff, Harrison, Sabah, Murare, Dunne & Hassounah, 1982). This latter observation raises the possibility that praziquantel may lower the ability of the parasite to evade host immunity by increasing the exposure of parasite antigens capable of acting as targets for host antibody, or antibody-armed cells at the worm surface. Consistent with this idea is the observation that adult schistosomes in praziquantel-treated mice are invaded a few hours after treatment by host granulocytes (Mehlhorn, Becker, Andrews, Thomas & Frenkel, 1981).
A preliminary study of the nature of infection and immunity in chickens given an attenuated line of Eimeria acervulina
Authors: McDonald V. , Ballingall S. , Shirley M. W. 
Published: June 2009

SUMMARYThe Houghton (H) strain of Eimeria acervulina was attenuated by serial passage through chickens of the first oocysts produced during infection. This selection pressure resulted in a reduction in the pre-patent period of the parasite, shown to be due to the selection of a line predominantly with only 3 instead of 4 generations of schizonts. The precocious line had a reproductive potential much lower than that of the parent strain and it was significantly less pathogenic. Chickens given oocysts of the precocious line were almost completely immune to challenge with the Houghton strain.
An analysis of variations in the age structure of Fasciola hepatica populations in sheep
Authors: Smith Gary 
Published: June 2009

SUMMARYThe processes which govern the age structure of Fasciola hepatica populations in sheep were investigated by means of a simple mathematical model. The mortality of the metacercariae on the pasture was shown to be a factor of major importance. The mortality rate depends on the micro-climate that prevails at the pasture surface, and thus the age distribution curve of a population of flukes is also determined in part by the weather. This has important implications for the chemotherapy of fascioliasis: flukicides are not equally effective over the whole range of age-classes of parasite and so the factors which govern the age distribution curve of the parasite population within individual hosts ultimately determine the efficiency of chemotherapy.
Monoclonal antibodies against surface antigens of schistosomula of Schistosoma mansoni
Authors: Taylor D. W. , Butterworth A. F. 
Published: June 2009

SUMMARYMonoclonal antibodies have been produced after fusion of NS-1 murine myeloma cells with spleen cells from mice immunized either by chronic primary infection or with irradiated cercariae: in both cases, animals were challenged with live cercariae 7 days before fusion. The initial cultures were screened for anti-schistosomular antibodies both by a radioimmunoassay with whole schistosomulum extracts and by immunofluorescence. There was no correlation between the two techniques and subsequent screening was carried out by immunofluorescence. Cloning was carried out in soft agar and 7 cloned cell lines, from 5 initial cultures, were selected for detailed study. Products of 6 of these 7 lines were monoclonal, as judged by isoelectricfocusing of [35S]methionine-labelled supernatant fluids, and their binding to live schistosomula was specific. None of the antibodies showed detectable activity in mediating eosinophil- or complement-dependent damage to schistosomula in vitro. However, 2 antibodies were successfully used to isolate surface proteins with an apparent molecular weight of 24000 on SDS-polyacrylamide gel electrophoresis.