bluuebunny/crossref_metadata_2025_split huggingface dataset:
The survival of the cercariae of Schistosoma mansoni in relation to water temperature and glycogen utilization
Authors: Ruth Lawson J. , Wilson R. A. 
Published: June 2009

SUMMARYSurvival curves for cercariae of Schistosoma mansoni maintained at different temperatures were determined. Between 15 and 35 °C the curves were of reverse sigmoid form and the probit transformation gave a statistically good fit. The slope of the regression lines fitted to the probit transformations increased exponentially as the temperature rose. Above 35 °C heat intolerance became important and increased exponentially as the temperature rose. Below 15 °C, cold intolerance caused an initial high level of mortality followed by an extended period with insignificant mortality. The glycogen content of whole cercariae and separated cercarial bodies and tails was measured during ageing. The glycogen content of whole cercariae declined exponentially during ageing. This was a product of exponential decreases in the glycogen content of both the body and the tail of the organism. The cercarial tail was shown to contain slightly over half of the total glycogen content. The rate of glycogen use was higher in the tail than in the body. A computer simulation model was used to demonstrate that the observed exponential use of glycogen could generate survival curves similar to those observed experimentally.
Nematode egg-shells
Authors: Wharton David 
Published: June 2009

SUMMARYThe transmission of parasites often involves a high mortality of free-living stages in the environment outside the host. This may be offset by a high biotic potential. In addition, adaptations of nematode eggs and larvae that ensure their survival or increase their chances of infecting a host will reduce the potential wastage rate. Increasing transmission will have an effect equivalent to increasing the fecundity of the parasite and, energetically, may be the more favourable strategy.
Isolation and antigen analysis of surface tegument membranes from schistosomula ofSchistosoma mansoni
Authors: Taylor D. W. , Wells Pamela Z. 
Published: June 2009

SUMMARYThe outer tegument membranes ofSchistosoma mansonischistosomula have been removed by mechanical disruption in a hypotonic salt solution and partially purified by differential and sucrose density gradient centrifugation. Fractionation was monitored by measuring increase in specific activity of bound [125I] wheat-germ agglutinin (WGA), alkaline phosphatase and calcium-stimulated ATPase. Two-dimensional IEF/SDS polyacrylamide gel electrophoresis was used to analyse the peptide composition of the isolated membranes and to compare and contrast with lactoperoxidase/glucose oxidase surface labelled peptides. At least 35 surface-labelled peptides were resolved on the two-dimensional maps: all were also present in the membrane material recovered from the sucrose gradient. Western blot analysis demonstrated a marked heterogeneity in the antibody response of infected human patients to individual membrane antigens. The antigenic profile of membranes isolated from cercariae, 18 and 96 h schistosomula were compared using Western blots: some minor differences were observed between the three preparations.
The ultrastructure of the pseudohaptoral squamodiscs of Diplectanum aequans (Monogenea)
Authors: Shaw M. K. 
Published: June 2009

SUMMARYThe ultrastructure of the pseudohaptoral squamodiscs of the monogenean Diplectanum aequans is described. The most prominent feature of the squamodisc is the presence of epidermally-embedded spines which are covered by the outer epidermal membrane. These spines, which are ‘hollow’, are composed of a moderately electron-dense material with denser fibrils embedded within it. The squamodisc epidermis is similar in appearance to the haptor epidermis, with the exception of the epidermis ‘inside’ the spines. Here the epidermis contains free ribosomes and stacks of alternating electron-lucent/electron-dense, membrane-bound sacs. The arrangement of the musculature of the spines is described. The free, prehensile, edges of the squamodiscs contain numerous radially orientated nerves, some of which are assumed to be mechano-receptors.
The establishment and population biology of the eye-fluke Tylodelphys podicipina (Digenea: Diplostomatidae) in perch
Authors: Kennedy C. R. 
Published: June 2009

SUMMARYThe introduction, establishment and subsequent history of a population of the eye-fluke Tylodelphys podicipina in perch in a small lake was studied over a period of 2 years. The introduction was a natural, chance colonization, and within 2 years of its first appearance the parasite was infecting 100% of the 0 + perch. Its dispersion within the perch population was initially random and fitted a Poisson model, but subsequently it became over-dispersed. Infection of fish took place only in or about June and only young of the year fish were susceptible. Fish were infected on one occasion only, shortly after birth, and there was no subsequent re-infection or mortality within the eye. The parasites lived for at least 2 years and there was no evidence of parasite-induced host mortality. Infection levels are thus an indication of the recruitment level in the year in which the fish were born. T. podicipina therefore differs from all other species of eye-flukes, which accumulate in fish throughout their life, but this infection strategy facilitates transmission of the parasites to their definitive host. Lower infection levels in older fish here and in other localities are considered to be due to the parasite being a recent introduction to the British fauna, and to its still being in the expansion phase of colonization in all localities.
Nematospiroides dubius: the course of primary, secondary and tertiary infections in high and low responder Biozzi mice
Authors: Jenkins D. C. , Carrington Trudi S. 
Published: June 2009

SUMMARYBiozzi mice of Selections 1 and 3, each exhibiting either high- or low- antibody responses to a wide range of antigens, were exposed to primary, secondary and tertiary infections of the nematode, Nematospiroides dubius. The course of these infections was followed by monitoring egg output and by examination of the worm burdens on the 14th day after each exposure to the parasite. When exposed to a primary infection, high and low responders were equally susceptible to the parasite, and the egg production of the infections was similar in all groups. However, when the mice were exposed to a 2nd infection of N. dubius, marked differences in the susceptibility of the hosts were seen. The high-responder mice of both Selections 1 and 3 were significantly more resistant to infection, far less adult worms being found in these. Resistance to a 3rd and final infection of the parasite was amplified appreciably in all groups but, again, the high-responder mice were significantly more resistant than the low responders. These results imply that host antibodies play an essential role in immunity to this parasite and that resistance cannot be attributed solely to non-specific macrophage activity or cell-mediated immune reactions, since the latter are equivalent in high and low lines and the macrophages of the Ab/L line of Selection 1 are hyperactive.
Recovery of parasites at different stages of migration following infection of rats withSchistosoma mansoni
Authors: Knopf P. M. , Mangold Beverly L. , Makari G. J. 
Published: June 2009

SUMMARYThe technique of tail amputation is utilized as a method for interrupting the migration process ofSchistosoma mansonischistosomula from the skin of Fischer rats infected by exposure of the tail to cercariae. The yields of schistosomula recovered from the lungs at different times post-infection are compared, using rats with or without tail amputation. Residence times of schistosomula in skin and lungs, as well as their transit time and efficiency of migration between these sites, are estimated. At least one-third of the infecting cercariae migrate from skin to lung in rats. Amputation of the tail on days 4 or 5 post-infection isolates a definable number of schistosomula in the lung and their migration to the portal circulation can be followed. The kinetics of this migration in rats and mice is compared and a significant difference is revealed.
The activity of drug combinations against established infections of rodent malaria
Authors: Hill J. 
Published: June 2009

SUMMARYIn the experiments reported here treatment (with a single dose or daily for 4 days) was delayed until 3 days after inoculation. Various combinations of M&B 35769, 2:4-diamino-5-[3(4–4′-chlorophenylphenoxy)propyl-l-oxy]-6-methylpyrimidine HC1, plus sulphadoxine, and of M&B 35769 plus dapsone, were examined and it was concluded that no universally ideal ratio of constituents in a combination is possible because the optimum ratio depends upon the activity of the constituents on their own and therefore varies from strain to strain. Activity was assessed on the 24th day after infection. M&B 35769 was markedly superior to pyrimethamine against all strains when the compounds were given on their own but, although it showed good potentiation with sulphadoxine and dapsone, much of its lead over pyrimethamine was lost in combination. M&B 36821 2–4-diamino-5-[3-(3,4′-dibromobiphenyl-4-oxy)-propyl-l-oxy]-6-methyl pyrimidine HC1, was more active than M&B 35769 against pyrimethamine- and cycloguanil-resistant strains but not against sensitive strains.
Fatty acid and cholesterol synthesis in mice infected with the tapewormHymenolepis microstoma
Authors: Rath E. A. , Walkey M. 
Published: June 2009

SUMMARYInfection withHymenolepis microstomasignificantly affected the lipid metabolism of young male Balb/C mice. Infection increased the rates of hepatic fatty acid and cholesterol synthesis and cholesterol synthesis by the gut. Decreases were recorded in testicular fatty acid synthesis and in the weights of testes and white epididymal adipose tissue. Plasma glucose decreased rapidly during infection. The observed changes in lipogenesis could not be attributed to changes in food intake or body temperature. The changes are discussed in relation to nutritional interactions between host and parasite and the possible effects on host hormone levels. The presence of newly synthesized fatty acid inH. microstomais also reported.
Differences in biological characteristics of two strains of the cestode Hymenolepis diminuta
Authors: Kino H. , Kennedy C. R. 
Published: June 2009

SUMMARYBiological characteristics of infectivity, growth rate and fecundity of Hymenolepis diminuta isolated from wild Rattus rattus in Japan were compared with parasites of Texas origin maintained for several generations in this and many other laboratories in laboratory bred Rattus norvegicus. The timing of development and maturation was similar in parasites from both sources, but the mean parasite dry weight was less and the mean egg production lower in Japanese parasites in both single and multiple infections. The differences persisted over 10 weeks in single infections, and were unaffected by rat strain. In all experiments there was much greater variation and heterogeneity in the biological characteristics of the Japanese parasites. It was concluded that the Texas parasites were better adapted to R. norvegicus and in the course of adaptation had become more homogeneous, and that the difference between the parasite strains had a complex genetic basis. Some Japanese parasites of the early isolated generations failed to produce normal eggs, but the proportion of these decreased in later generations. However, selected individual Japanese parasites whose egg production was equal to that of parasites of Texas origin did not produce offspring of larger mean size or higher mean fecundity, and heterogeneity of these characteristics was maintained. In the intermediate host, the mean number of cysticercoids of the Japanese isolate per beetle was higher than that of the Texas strain in Tribolium confusum but lower in Tenebrio molitor. The greater heterogeneity exhibited by Japanese parasites and the genetic basis of the strain difference are discussed with particular reference to geographical isolation, differences in definitive hosts and co-evolution of wild and laboratory host and parasite populations.
A mathematical model of the population biology ofOstertagia ostertagiin calves and yearlings
Authors: Grenfell B. T. , Smith G. , Anderson R. M. 
Published: June 2009

SUMMARYA mathematical model of the population biology ofOstertagia ostertagiis described. The model assumes that the natural control and regulation of parasite numbers is mediated by four processes: the effect of climate on the development and survival of the free-living stages; changes in the rate of establishment of the infective larvae, and density-dependent variations in parasite survival and fecundity. The model is used to compare the course of the infection in two groups of calves. One group is assumed to have been reared under conditions typical of S.E. England and the other under conditions typical of Louisiana, USA. The more general behaviour of the model is discussed in the context of sensitivity analysis. The model is an excellent mimic of the epidemiology of bovine ostertagiasis. It can be used as a simple screening procedure to help determine which of many possible anthelmintic control strategies should be selected for more detailed examination in the field, and it provides a theoretical framework within which ideas concerning the epidemiology of parasitic gastro-enteritis can be assessed and refined.
Glucose phosphate isomerase isozymes as genetic markers for lines of Eimeria tenella
Authors: Nakamura T. , Konishi T. , Kawaguchi H. , Hayashi Y. 
Published: June 2009

SummaryTwo strains of Eimeria tenella with different decoquinate sensitivity and different glucose phosphate isomerase (GPI) isozymes were used in genetic recombination experiments: a line derived from a laboratory strain (NIAH) was decoquinate-resistant (DR) and had the isozyme GPI-9, while a field isolate (Iwate strain) was decoquinate-sensitive (DS) and had GPI-1. Coccidia-free chickens were orally inoculated with mixed oocysts of the two strains and parasites of the F1 generation were recovered. The F1 progeny showed both forms of the isozyme. Next, oocysts of the F1 progeny were passaged through chickens given the decoquinate-containing diet. The F2 progeny also had GPI-1 and GPI-9, indicating crossfertilization between the two strains. Six single oocysts were isolated from F2 progeny; 1 showed both phenotypes of GPI, 1 had GPI-1 and the remaining 4 lines had GPI-9. Analysis of the amount of GPI in recombinant oocysts suggested that the proliferation rate of the DR strain was slower than that of the DS strain. We concluded that GPI isozymes in E. tenella can serve as useful markers in experiments on chicken coccidia.
Sex differences and cross-immunity in DBA/2 mice infected withL. mexicanaandL. major
Authors: Alexander J. 
Published: June 2009

SummaryFemale DBA/2 mice were found to be highly resistant toLeishmania mexicanaand rarely developed lesions even when inoculated subcutaneously with high numbers (5 × 106) of amastigotes. Male DBA/2 mice, on the other hand, were much more susceptible to this parasite and often developed non-healing lesions even when inoculated subcutaneously with comparatively few (5 × 104) amastigotes. Conversely, although both male and female DBA/2 mice developed ulcerating lesions when inoculated subcutaneously withL. majoramastigotes, lesions invariably healed in males but did not heal in females. Male DBA/2 mice recovered fromL. majorinfection subsequently were found to be resistant to subcutaneous challenge withL. mexicana. Conversely female DBA/2 mice that had failed to develop lesions when infected withL. mexicanadeveloped lesions which healed following subcutaneous challenge withL. major. Thus there is bilateral cross-immunity betweenL. mexicanaandL. majorin DBA/2 mice which overrides differences in sex-determined susceptibility to both organisms.
Integrated control of ticks and tick-borne diseases of cattle in Africa
Authors: Young A. S. , Groocock C. M. , Kariuki D. P. 
Published: June 2009

SummaryThe problems caused by tick and tick-borne diseases for livestock particularly cattle on the African continent are described and discussed. The control of ticks and tick-borne diseases must receive high priority in Africa with regard to both research and control application because of their widespread distribution in areas of high livestock potential and productivity. The conventional methods of tick and tick-borne disease control are discussed and are found to be inadequate in the conditions prevailing in Africa. Methods of integrated control are suggested and discussed in light of recent development in control methods and those still under development. Any one of these methods may not be adequate to control the problem on its own but when several of the methods are combined an economic and robust integrated control is likely to result. Encouragement is given to attempt this approach in Africa to solve what must be the largest animal health problem of livestock remaining in the world.
The effects of cholinergic and serotoninergic drugs on motilityin vitroofHaplometra cylindracea(Trematoda: Digenea)
Authors: McKay D. M. , Halton D. W. , Allen J. M. , Fairweather I. 
Published: June 2009

SummaryThe spontaneous activity of the somatic muscle of the amphibian lung fluke,Haplometra cylindraceahas been recordedin vitro, using an isometric force transducer system. Normal movement consisted of a continuous series of regular contractions which were maintained for over 4 h. Acetylcholine (ACh) inhibited motility and at a concentration of 1 χ 10–3M induced a flaccid paralysis. A similar response occurred with the cholinomimetic drugs, carbachol and nicotine, although in these instances the inhibition was less easily reversed by washing with frog Ringer. The inhibitory effect of ACh was blocked by d-tubocurarine but not by atropine.
Soil-transmitted helminth infections in school children from Cocle Province, Republic of Panama
Authors: Robertson L. J. , Crompton D. W. T. , Walters D. E. , Nesheim M. C. , Sanjur D. , Walsh E. A. 
Published: June 2009

SummaryA survey was carried out to determine values for the prevalence and intensity of infection of intestinal helminths in children living in Cocle Province, Republic of Panama. The data set consisted of the results of microscopic examinations (modified Kato Katz technique) of stool samples collected in November 1987 from 661 children attending primary schools in 4 communities in the province. The overall prevalences of Ascaris lumbricoides, hookworm and Trichuris trichiura infections were found to be 18·2, 12·0 and 27·5% respectively. There were significant differences between the infection prevalence values for children attending the different schools, but not with respect to age or sex. Positive associations were detected between particular pairs of infections and these were most evident when Trichuris trichiura was involved. The data revealed evidence of a positive association between siblings at one school only for each helminth infection.
Pulsed transmission of Pseudodiplorchis americanus (Monogenea) between desert hosts (Scaphiopus couchii)
Authors: Tinsley R. C. , Jackson Helen C. 
Published: June 2009

SummaryTransmission of the monogenean Pseudodiplorchis americanus is restricted to the brief period when its host, the desert toad Scaphiopus couchii enters temporary water to breed. This study followed parasite recruitment into one host population in Arizona, USA, during the spawning season (July). Torrential rainfall triggered 3 successive assemblies. Amongst males, which may enter each assembly, the 3 pulses of invasion led to an approximate doubling of mean worm burdens at each exposure, culminating in 100% prevalence and a mean intensity of over 100 larvae/host. Females, which generally enter only one assembly, acquired a mean of about 40 larvae/host. Each exposure is limited to a maximum of 7 h by strictly nocturnal host activity, and the force of infection increased exponentially: around 10% of recruitment occurred in the first 3 h, and more than 30% in the last 1 h. Correlation of recruitment into males with parasite reproductive potential suggests that individual oncomiracidia had a 30% chance of invasion. Although invasion of the desert host relies on an aquatic infective stage, host behaviour ensures that targets are concentrated in space and time, and the parasite's annual reproductive output is synchronized with a period of host vulnerability totalling less than 24 h/year.
Plasmodium falciparumgrowth inhibition by human plateletsin vitro
Authors: Peyron F. , Polack B. , Lamotte D. , Kolodie L. , Ambroise-Thomas P. 
Published: June 2009

SummaryPlatelets take an active part in immunological processes as well as in haemostasis, especially in the host-parasite relationship. Our aim is to assess the growth ofPlasmodium falciparum, cultured in human erythrocytes in the presence of fresh washed human platelets, since thrombocytopaenia is frequently observed during malarial infections. Our results show that platelets induce a dose-related growth inhibition ofP. falciparum. Both proliferation and maturation of intraerythrocytic stages of the parasite are inhibited. This growth inhibition is triggered by the parasite itself as neither specific antibodies nor any other components are needed to activate platelets. Activated platelets are directly toxic since complement is not involved. Furthermore, inhibition is not mediated by erythrocyte lysis or by toxic oxygen metabolites. Platelets induce an inhibition ofP.falciparumgrowth, at leastin vitro, although the importance of their role playedin vivoin malarial immunity has yet to be evaluated.
Biochemical characteristics of the metacyclic forms ofLeishmania majorandL. mexicana mexicana
Authors: Mallinson D. J. , Coombs G. H. 
Published: June 2009

SummaryMetacyclic forms ofLeishmania majorand putative metacyclics ofL. mexicana mexicanawere found to occur in abundance in stationary phase cultures. These forms have been compared in several ways with promastigotes from mid-log phase cultures and, in the case ofL. m. mexicana, amastigotes. Metacyclics are smaller, contain less protein and appear more active than other promastigotes. Both forms of promastigote respire at a high rate in the absence of exogenous substrate. The free amino-acid contents of the various forms of the two species have been analysed. They differ in detail but alanine was the major amino acid in all cases. The isoenzyme content of the different forms differed significantly. That of the putative metacyclics ofL. m. mexicanawas in several respects more similar to amastigotes than promastigotes, suggesting that the form is pre-adapted for life in a mammal. Metacyclics ofL. majorapparently did not divide in culture but transformed back over a period of 48 h to mid-log phase cells. The results provide further detail of the molecular differences between mid-log phase and metacyclic promastigotes and confirm that metacyclics are a distinct form in the life-cycle.