bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mouse-to-mouse transmission of infections with Giardia muris
Authors: Belosevic M. , Faubert G.M. , Maclean J. D. 
Published: June 2009

SUMMARYThe transmission of infection with Giardia muris among CD-I mice was quantified by determining the duration of the latent period and intensity of cyst release during the acute phase of the infection. Housing of experimentally inoculated mice with uninfected mice in the same cage resulted in 100% transmission of infection. The dissemination of the infection was faster if experimentally inoculated hosts were passing high numbers of cysts at the time of housing with uninfected animals. The course of ‘naturally’ acquired and experimentally induced infections was similar. We conclude that G. muris has a high transmission potential and that the number of cysts randomly consumed does not influence the course and eventual outcome of the infection.
Population dynamics in echinococcosis and cysticercosis: biological parameters of Echinococcus granulosus in dogs and sheep
Authors: Gemmell M. A. , Lawson J. R. , Roberts M. G. 
Published: June 2009

SUMMARYThe numerical distributions of Echinococcus granulosus in an experimental dog population are described. At all dose rates of protoscoleces from 10 to 175000 the distribution of worms was over-dispersed. Host age had no effect. There was a direct proportionality between the infective-stage density and rate of infection, and between the latter and the index of clumping. The worm burdens were significantly higher in the proximal than distal portions of the small intestine. Lengths of the 3- and 4-segmented worms increased from 4 to 10 and 4 to 8 weeks of age, respectively. Thereafter apolysis was asynchronous and could not be determined. Eggs were first detected in the faeces at 6 weeks and the mean age at oogenesis was 7·26 weeks. Retarded growth of the whole population of worms was observed in some dogs. For the first few infections, worm burdens varied widely in the same dog, but by the 6th infection 50% of the dog population had developed a relative insusceptibility to infection. Growth or oogenesis of the worms were not affected. A short-acting immune response was artificially induced in some dogs following the parenteral injection of activated embryos of E. granulosus, Taenia hydatigena, T. ovis, T. multiceps, T. pisiformis and T. serialis. The response affected either the number of worms established, growth or oogenesis or all three parameters. There was a strong positive correlation between numbers and lengths of worms in dogs with acquired and induced immunity, indicating that no ‘crowding’ effects were involved. In sheep populations the mean number of cysts which established was directly proportional to the number of eggs given, implying that there was no negative feedback mechanism operating at this stage of the life-cycle. The distribution of the larval population in sheep was over-dispersed and the index of clumping increased with the size of the egg dose from 25 to 2500 eggs. Protoscoleces were first observed in cysts at 2 years and the proportion producing them increased with age, with an estimate of 50% of cysts containing protoscoleces at 6 years. No deaths were observed in dogs or sheep even when high parasite burdens were present, implying that E. granulosus does not regulate the population of its hosts.
Stereological estimation of gap junction surface area per neuron in the developing nervous system of the invertebrate Mesocestoides corti
Authors: Burns A. J. , Howard C. V. , Allen J. M. , Van Velsen D. , McKerr G. 
Published: June 2009

SUMMARYAs a major morphological feature in establishing the form of the nervous system, it is recognized that neurons are initially overproduced, then naturally occurring cell death reduces the neuron number to the functional requirement. However, the mechanisms controlling the selective elimination of certain neurons during a general phase of cell death are not fully understood. One event that seems to be pivotal is the establishment of neural connections, the degree of which may be influential regarding the fate of specific neurons. However, little quantitative evidence is available to either support or refute this theory. In this current study, a Stereological measurement of gap junction per neuron was carried out within the invertebrate model system of the tapeworm metacestode Mesocestoides corti, which has previously been shown to overproduce neurons during the asexual reproduction stage of its life-cycle. Novel Stereological estimation methods with ‘ vertical sections’ indicated that prior to asexual division the cerebral ganglion possessed approximately 268 neurons, each with a gap junction surface area of 250 μm2. As division progressed, the neuron number increased to approximately 700, while the total surface area of gap junction remained statistically unchanged. As a result the surface area of gap junction per neuron decreased to 106 μm2, less than half that in the undividing stage. These results provide the first non-biased quantitative data regarding changes in the mean surface area of gap junction per neuron in a developing cerebral ganglion.
The within-host cellular dynamics of bloodstage malaria: theoretical and experimental studies
Authors: Hetzel C. , Anderson R. M. 
Published: June 2009

SUMMARYThe properties of a mathematical model of bloodstage infection with a single strain of malaria were investigated. Analysing the cell population dynamics in theabsenceof a host immune response we demonstrate a relationship between host and parasite parameters that defines a criterion for the successful invasion and persistence of the parasite. Important parameters are the rates of merozoite production and death and those of erythrocyte production, death and invasion. We present data from experiments designed to evaluate the erythrocyte invasion rate in a rodent malaria system. The model generates patterns of parasitaemia in good qualitative agreement with those seen inPlasmodium bergheiinfections. The sole force behind the rise and fall in parasitaemia in the model without immunity is the density of susceptible erythrocytes, suggesting that resource availability is an important determinant of the initial pattern of infectionin vivo. When we incorporate a simple immune response into the model we find that immunity against the infected cell is much more effective at suppressing parasite abundance than immunity against the merozoite. Simulations reveal oscillating temporal patterns of parasite abundance similar toP. c. chabaudiinfection, challenging the concept that antigenic variation is the sole mechanism behind recrudescing patterns of infection.
Enzyme polymorphism in Endotrypanum and numerical analysis of isoenzyme data
Authors: Franco A. M. R. , Momen H. , Naiff R. D. , Moreira C. F. S. , Deane M. P. , Grimaldi G. 
Published: June 2009

SUMMARYIn this study, we have analysed enzyme polymorphism among a group of protozoan parasites of the genus Endotrypanum (Kinetoplastida: Trypanosomatidae). Seventeen stocks of Endotrypanum spp. isolated from sloths (Choloepus didactylus and C. juruanus) in the Amazon Region of Brazil were analysed by enzyme electrophoresis, and their electromorphic profiles were compared with reference strains reported previously. The 16 enzymic loci were analysed, and the strains were classified into zymodemes, each representing parasites with unique enzyme profiles. Each zymodeme was considered as an elementary taxon, and using numerical analyses (cladistic, agglomerative hierarchical and ordination techniques) the genus was shown to be monophyletic and the 12 zymodemes characterized could be divided into 3 groups (A, B, C). The heterogeneous population (which may represent a complex of parasite species or strains variants) showed, however, no correlation with the origin (i.e. host species involved or geographic area of isolation) of Endotrypanum stocks. Eight isolates of Endotrypanum sp. from Rondonia State (Brazil) and a parasite strain from Panama were clustered together into a zymodeme, which was phenetically closely related to the E. monterogeii from Costa Rica. The data indicate that E. schaudinni is a species complex.
Isolation, characterization and immunolocalization of a globin-like antigen from Ostertagia ostertagi adults
Authors: De Graaf D. C. , Berghen P. , Moens L. , De Marez T. M. , Raes S. , Blaxter M. L. , Vercruysse J. 
Published: June 2009

SUMMARYWestern blot analysis using an anti-globin rabbit serum Rb94 revealed a major band of 17 kDa in extracts of Ostertagia ostertagi adults and 4th-stage larvae. The adult stage globin-like antigen (OoAdGlb) was purified from total worm extracts by liquid chromatography. The protein has an estimated molecular mass of 36 kDa under non-reducing conditions, suggesting a dimeric structure containing 2 non-covalently linked 17 kDa monomers. Tryptic peptides were sequenced and showed strong similarities with the globins of free-living and parasitic nematodes. Immunolocalization revealed the presence of this globin-like antigen in the body wall musculature and/or the cuticle of O. ostertagi adults. An enzyme-linked immunosorbent assay based on the purified OoAdGlb showed no differences in response between calves infected by O. ostertagi and/or Cooperia oncophora and the negative controls.
Malaria parasites enhance blood-feeding of their naturally infected vector Anopheles punctulatus
Authors: Koella J. C. , Packer M. J. 
Published: June 2009

SUMMARYWe investigated the blood-feeding behaviour of a natural population of the human-feeding mosquito Anopheles punctulatus in Iguruwe, Papua New Guinea. In particular we investigated the relationship between the mosquitoes' blood-feeding behaviour and their infection by the malaria parasites Plasmodium falciparum and P. vivax. Female mosquitoes were caught at 4 times of the night, the amount of blood they had obtained was measured and their status of infection was evaluated. Among uninfected mosquitoes the bloodmeal size steadily increased through the night, possibly because they were progressively less likely to be disturbed by human activity as the night drew on. Infected mosquitoes, on the other hand, tended to feed maximally at all times of the night. This suggests that infected mosquitoes were more tenacious in their blood-feeding behaviour, being either less readily disturbed during a bout of feeding (and thus feeding longer) or more likely to return to continue their feed following disturbance (and thus feeding several times). Either change would increase the parasites' rate of transmission. We conclude that in this natural situation the two species of malaria parasites modified the mosquitoes' behaviour with the effect of increasing their own transmission.
Serological response of ascarid-free dogs to Toxocara canis infection
Authors: Glickman L. T. , Dubey J. P. , Winslow L. J. 
Published: June 2009

SUMMARYAntibodies to Toxocara were measured by enzyme-linked immunosorbent assay (ELISA) in sera of ascarid-free dogs which had been fed 0,100 or 10000 embryonated T. canis eggs. Dogs fed 10000 eggs developed higher titres than those given 100 eggs and larvae failed to complete their migration to the gut. In addition, in dogs given 100 eggs, there was a significant negative correlation between the number of worms in the gut and granulomatous foci in the lung. The data suggest that the ELISA is sensitive and specific for Toxocara infection in dogs.
Effects of Ostertagia circumcincta infections on plasma gastrin in sheep
Authors: Anderson N. , Hansky J. , Titchens D. A. 
Published: June 2009

SUMMARYRadio-immunoassay of plasma gastrin showed that hypergastrinaemia developed in sheep during experimental infections with Ostertagia circumcincta. Elevations of plasma gastrin occurred within 8 days of the first dose of infective larvae, with the most marked increase being after 11–20 days when adult worms would be expected to be present in the abomasum. Increases of plasma gastrin levels from 69·0 ± 7·6, 28·7 ± 5·3, 48·7 ± 5·9 and 60·6 ± 9·4 pg/ml before infection to maxima of 650, 230, 900 and 750 pg/ml respectively were recorded in 4 sheep infected for the first time. In 2 others which had been previously infected and then treated with anthelmintic, plasma gastrin rose from 16·0 ± 4·0 and 377 ± 87 pg/ml to maxima of 260 and 900 pg/ml at 24 and 29 days after re-infection, respectively. The cause of hypergastrinaemia has not been established. The elevation of abomasal pH which occurs in ostertagiasis may result in increased gastrin levels but is thought not to be the only cause since plasma gastrin increased before the abomasal pH rose and developed in sheep infected for a second time although their abomasal contents remained at pH 4·0 or lower. The presence of the parasite is critical for development of hypergastrinaemia as shown by return of the gastrin level to normal following therapy with an anthelmintic. It was shown that the parasites do not depend on the hypergastrinaemia since O. circumcincta became established in antrectomized sheep in which hypergastrinaemia did not develop.
A glycoprotein specific to the amphids of Meloidogyne species
Authors: Stewart G. R. , Perry R. N. , Alexander J. , Wright D. J. 
Published: June 2009

SUMMARYIndirect immunofluorescence studies using a rabbit polyclonal antiserum have been used to localize the presence of a 32 kDa glycoprotein in the region of the amphids of 2nd-stage juveniles of the root-knot nematode, Meloidogyne incognita. Similar immunoreactivity was also demonstrated in 5 other Meloidogyne species but was not found in representatives of 8 other nematode genera including the closely related cyst nematodes (Globodera and Heterodera). Immunoelectron microscopical studies have shown that the immunoreactivity in M. incognita is associated with the secretory material filling the amphidial channel and probably with the sheath cell.
Factors contributing to the retardation of development of Obeliscoides cuniculi in rabbits
Authors: Fernando M. A. , Stockdale P. H. G. , Ashton G. C. 
Published: June 2009

The relationship between the age of infective O.cunictili larvae and the proportion that remained retarded in a subsequent infection was investigated. The proportion of retarded larvae recovered was found to depend on the length of time and the temperature at which infective larvae were stored prior to infection. At 4 °C the level of retardation was found to increase with increase in the length of storage until a maximum was reached. Further storage tended to decrease the proportion of larvae that remained retarded. These effects were found to be less marked when the larvae were stored at a higher temperature. At 17 °C the maximum level of retardation reached was lower and the process of the increase and the decrease in retardation was of shorter duration. An increase in the number of larvae from 200 to 6000/rabbit did not appreciably change the proportion that remained retarded.We are most thankful for the advice and criticisms of Dr J. D. Dunsmore. The
skilled technical assistance of Mr Ted Eaton is gratefully acknowledged. This work
was supported by the Ontario Department of Agriculture and Food.
Identification of the larvae of Hyalomma (Hyalomma) anatolicum subspecies (Ixodoidea: Ixodidae) with special reference to chaetotaxy
Authors: Snow Keith R. 
Published: June 2009

An account is given of the morphological characteristics of the larvae of Hyalomma anatolicum anatolicum and H. a. excavatum. Emphasis is placed on the importance of chaetotaxy in the identification of the larvae.I am most grateful to Professor Don R. Arthur for reading the manuscript and for his most useful advice and encouragement. Also I wish to express my sincere thanks to Dr R. P. Chaudhuri, Dr C. M. Clifford, Dr V. Dhanda, Dr H. Hoogstraal and Profesor B. Feldman-Muhsam for supplying me with specimens.
The effect ofTrichinella spiralisinfection on the mechanical properties of the mammalian diaphragm
Authors: Harwood C. L. , Young I. S. , Lee D. L. , Altringham J. D. 
Published: June 2009

SUMMARYTrichinella spiralislarvae infect and develop within skeletal muscle cells causing major changes to their mechanical properties. The aim of this investigation was to determine the effects ofT. spiralison the power output and fatigue resistance of the mammalian diaphragm under conditions simulatingin vivooperation and to relate these to respiratory performance. Infection withT. spiralisleads to major reductions in mechanical stress, work, power output and fatigue resistance. These changes are associated with the number of larvae present in the muscle and the duration of infection. However, the initial decline in mechanical performance occurs during the onset of infection when there are few larvae observed within the muscle cells, indicating thatT. spiralismay affect the properties of muscle before encapsulation. This may correspond to the host's inflammatory response and the effects of larval excretory/secretory products. The decline in mechanical performance will have a profound effect on respiration both at rest and during exertion. This must influence the behaviour of the host and increase its chance of capture by predators, which is likely to benefit the parasite by facilitating its transmission.
Host recognition behaviour predicts host suitability in the entomopathogenic nematode Steinernema carpocapsae (Rhabditida: Steinernematidae)
Authors: Lewis E. E. , Ricci M. , Gaugler R. 
Published: June 2009

SUMMARYSteinernema carpocapsae (Rhabditida: Steinernematidae) host recognition behaviour was assessed and compared with 2 measures of host suitability. Previous research showed that S. carpocapsae infective juveniles respond to host cues in a hierarchical order, with attraction to Galleria mellonella volatiles being stimulated by contact with G. mellonella cuticle. We measured host recognition behaviour by calculating the percentage response of S. carpocapsae infective juveniles to volatiles produced by G. mellonella last instars after the nematodes were exposed to the cuticle of 11 candidate arthropod hosts and 2 control surfaces. Host suitability was measured by nematode-induced mortality to candidate hosts at 2 nematode doses and the level of reproduction supported by each host. The highest recognition response was scored for Agrotis ipsilon (Lepidoptera: Noctuidae). This insect also incurred nearly 100% mortality due to nematode infection and supported the highest level of reproduction. Non-insect arthropods tested (Chilopoda and Isopoda) stimulated no behavioural response and were not susceptible to nematode infection. Other insect species elicited intermediate levels of the recognition response. There were significant correlations between behavioural response and nematode-induced mortality at the lower dose. The level of reproduction supported by the candidate hosts was also correlated with S. carpocapsae behavioural response.
The effect of invertebrate hormones and potential hormone inhibitors on the third larval moult of the filarial nematode, Dirofilaria immitis, in vitro
Authors: Warbrick E. V. , Barker G. C. , Rees H. H. , Howells R. E. 
Published: June 2009

SUMMARYThe effects of the insect hormones, ecdysone and 20-hydroxyecdysone, certain non-steroidal ecdysteroid agonists (RH compounds) and the inhibitor, azadirachtin, on the timing of the 3rd-stage moult of Dirofilaria immitis were investigated. 20-Hydroxyecdysone and RH 5849 when used at a concentration of 10−5 M, resulted in a premature timing of this moult. Azadiracthin, at a similar concentration, prevented moulting of most of the larvae to the 4th stage. The results are discussed in relation to the possibility of a hormonal role for ecdysteroids and neuropeptide-like compounds in the control of ecdysis in filarial nematodes, that maybe somewhat comparable to the system which is found in insects.
Experiments on the olfactory responses and host-specificity of the Oriental rat flea (Xenopsylla cheopis), (Siphonaptera: Pulicidae)
Authors: Shulov A. , Naor D. 
Published: June 2009

Factors governing the response of the Oriental rat flea, X. cheopis, to the white rat and to three murids were studied in an olfactometer.Starved females aged 5–10 days were attracted to white rats, whereas starved younger females were repelled or indifferent. Starved males, 1–10 days old, were either indifferent or were repelled.No clear-cut attraction of 7- and 8-day-old starved females towards the murids Meriones tristrami, Acomys dimidiatus and Microtus guentheri was observed.Starved females increased their weight during the first 8 days of life by 12·0%, while starved males lost 2·2%. Females kept in a vessel with a white rat showed a 115·2% weight gain, while males under the same conditions gained only 18·8% (Table 5).The authors wish to thank Dr F. G. A. M. Smit, of the British Museum (Natural History), Tring, Hertfordshire (England), for his valuable help in the preparation of the manuscript for this paper.
Testosterone-induced changes in phosphatidylcholine molecular species composition ofPlasmodium chabaudi-infected erythrocytes
Authors: Fiebig S. , Simões A. P. , Wunderlich F. , Op Den Kamp J. A. F. 
Published: June 2009

SUMMARYThis study is concerned with the influence of testosterone on the phospholipid class and the phosphatidylcholine molecular species composition of various fractions obtained from the blood ofPlasmodium chabaudi-infected mice. Blood plasma, infected erythrocytes, isolated parasites and erythrocyte membranes isolated from both non-infected and infected erythrocytes in the form of ghosts were analysed. In general, the phospholipid classes remained unaffected, while the phosphatidylcholine (PC) molecular species composition showed differences after testosterone treatment. In infected erythrocytes, there was a decrease in 16:0/20:4-PC and 18:0/20:4-PC and an increase in 16:0/18:2(16:0/20:3)-PC. The decrease of 16:0/20:4-PC was exclusively confined to parasites. The rise in 16:0/18:2(16:0/20: 3)-PC and the diminution of 18:0/20:4-PC occurred in the erythrocyte membrane of both infected ghosts and non-infected ghosts as well as in the blood plasma. It is suggested that these changes occur primarily in the plasma thereby influencing the erythrocyte membranes. The decrease in 16:0/20:4-PC supports the view of the independence of the parasite from the biosynthetic lipid pathways of its host cell.
Subcellular localization of Pfs16, a Plasmodium falciparum gametocyte antigen
Authors: Baker D. A. , Daramola O. , McCrossan M. V. , Harmer J. , Targett G. A. T. 
Published: June 2009

SUMMARYWe have used immunoelectron microscopy to investigate the subcellular location of Pfs16 in Plasmodium falciparum. It was detected in the outer membrane region of gametocytes and more specifically on the parasitophorous vacuole membrane (pvm), since, during gametogenesis when the pvm disintegrates, the majority of the antigen was detected on the remains of this membrane in multilaminated whorls and not on the gamete plasma membrane. The antigen was also present on other gametocyte cellular structures, including those which we believe to be Garnham bodies, present in the host cell cytoplasm of some gametocytes. The antigen was present too on the membrane surrounding cytostomes and the resulting food vacuoles in the parasite cytoplasm.