bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunological relationships during primary infection with Heligmosomoides polygyrus (Nematospiroides dubius): dose-dependent expulsion of adult worms
Authors: Robinson M. , Wahid F. , Behnke J. M. , Gilbert F. S. 
Published: June 2009

SummaryThe survival of Heligmosomoides polygyrus was monitored during primary infections in female C57Bl10, NIH and BALB/c mice at low and high intensities of infection. Survivorship curves were fitted for each data set and analysed. C57Bl10 mice, given either low or high intensities of infection, harboured parasites for 28–37 weeks, heavier infections surviving marginally but significantly longer. Essentially the survivorship curves of H. polygyrus in C57Bl10 mice could be accounted for by senility, the increased probability of worms with a longer life-span occurring at high infection intensities and, possibly, by a contribution from host-protective immune mechanisms in the terminal stages of infection. The pattern of survivorship was different in NIH and BALB/c mice. NIH mice showed weak but significant density-dependent suppression of parasite loss and infections in this strain did not exceed 27·5 weeks in duration. Primary infections in BALB/c mice were briefer still and showed marked dependence on parasite density. Thus low-level infections lasted 10–15 weeks whereas heavier infections survived for 21–34 weeks. The data suggested that both strains developed host-protective responses to adult H. polygyrus and that parasite survival was curtailed earlier than would be expected if senility alone was involved. The hybrid strains (C57Bl10 × NIH)F1 and (B10G × NIH)F1 both expelled H. polygyrus in a dose-dependent manner, worm loss commencing within 10 weeks of infection. In some experiments worm loss was clearly evident by weeks 4 and 6. These hybrid strains showed gene complementation in that adult worms were cleared considerably earlier than in parental strains.
Variation in resistance to isometamidium chloride and diminazene aceturate by clones derived from a stock ofTrypanosoma congolense
Authors: Peregrine A. S. , Knowles G. , Ibitayo A. I. , Scott J. R. , Moloo S. K. , Murphy N. B. 
Published: June 2009

SUMMARYNine clones were derived from a drug-resistantTrypanosoma congolensestock (IL 2856) and characterized in mice for their sensitivity to isometamidium chloride and diminazene aceturate. All clones were derived from the stock without drug selection and expressed high levels of resistance to isometamidium chloride (50% curative dose [CD50] values ranging from 1·5 to 5·1 mg/kg) and intermediate to high levels of resistance to diminazene aceturate (CD50values ranging from 5·1 to 21·0 mg/kg). By contrast, the isometamidium chloride and diminazene aceturate CD50values for a drug-sensitive clone,T. congolenseIL 1180, were 0·018 mg/kg and 2·3 mg/kg, respectively. For both drugs, there appeared to be significantly different levels in expression of drug resistance amongst the 9 clones derived from IL 2856. Isoenzyme analysis of 7 enzymes showed that all 9 clones expressed the same electrophoretic variants. Thus, all 9 clones were identical for these phenotypic markers. The clone which expressed the highest level of resistance to isometamidium in mice (IL 3270) was transmitted to Boran cattle via the bite of infectedGlossina morsitans centralis. IL 3270 produced an infection rate in tsetse of 5·0%. The resulting infections in cattle were shown to be resistant to intramuscular treatment with 2·0 mg/kg isometamidium chloride and 14·0 mg/kg diminazene aceturate. This contrasts with doses of 0·25 mg/kg isometamidium chloride or 3·5 mg/kg diminazene aceturate which are deemed sufficient to cure fully sensitive infections. Finally, 9 clones (subclones) were derived from IL 3270 and characterized in mice for their sensitivity to isometamidium chloride. Seven of the subclones expressed a significantly lower level of resistance to isometamidium than the parental clone and amongst the subclones there was significant variation in resistance. Thus, expression of a high level of resistance to isometamidium appears to be unstable in the rodent host and at least a component of the genetic determinant(s) for this drug-resistant phenotype is (are) likely to be unstable.
Developmental stages of Cyclospora talpae in the liver and bile duct of the mole (Talpa europaea)
Authors: Mohamed H. A. , Molyneux D. H. 
Published: June 2009

SUMMARYThe completed life-cycle of Cyclospora talpae, an extra-intestinal coccidian (Apicomplexa) of the liver of the mole (Talpa europaea). is reported. Oocysts sporulated within 12–14 days at room temperature (20–22 °C). Both macro- and micro-gametocytes developed independently within the nucleus of epithelial cells lining the bile duct as demonstrated by both light and electron microscopy. Merogony was seen in the mononuclear cells in the capillary sinusoids of the liver. Merozoites showed the typical ultrastructural features of the Apicomplexa. The life-cycle of C. talpae and the ultra-structure of the gametogonic and merogonic stages are reported; the ultrastructure of the merozoites is reported as the first description of this stage for the genus Cyclospora.
Epidemiological significance of vector–parasite interactions
Authors: Dye C. 
Published: June 2009

SUMMARYA great deal of published experimental evidence shows that parasite-induced changes in host choice, and biting and survival rates of bloodsucking insects are an important source of bias in estimates of Vectorial Capacity. I argue here that, because of the difficulties of handling these and other biases in practice, indices (based on the Vectorial Capacity) which purport to measure transmission rate are best used in a comparative rather than an absolute way. They should attempt to measure, not transmission rate, but changes in transmission rate. In this case, the less restrictive assumption that parasites are responsible for constant bias (rather than no bias) leads to relatively small errors. The results encourage a more optimistic view of the performance of classical entomological indices such as the parous rate. They should also help to redirect the principal epidemiological question about vector–parasite interactions: future studies should be concerned with the impact of parasites, not directly on Vectorial Capacity, but on the comparative measures which are actually used to evaluate transmission rate.
Hymenolepis diminuta (Cestoda) liberates an inhibitor of proteolytic enzymes during in vitro incubation
Authors: Pappas P. W. , Uglem G. L. 
Published: June 2009

SUMMARYHymenolepis diminuta liberated measurable amounts of ‘Lowry-positive material’ (LPM) and protein during incubation for 2 h in vitro. When tapeworms were incubated in the presence of bovine trypsin (BT), or when BT was added to the medium after removing the tapeworms, the enzyme's proteolytic activity was inhibited significantly. Centrifugation of the medium at 30 000 g yielded a pellet composed of tegumental elements, but this fraction did not inhibit BT. The 30 000 g supernatant fraction contained a chemical(s) that inhibited the proteolytic enzymes of the rodent host's intestinal contents (IC). The inhibitor(s) was stable following repeated freeze-thaw cycles, heat labile, and not degraded by BT or IC, and it inhibited the amidase activity of BT in a non-competitive manner.
Immunodiagnosis of taeniasis by coproantigen detection
Authors: Allan J. C. , Avila G. , Noval J. Garcia , Flisser A. , Craig P. S. 
Published: June 2009

SUMMARYImmunodiagnostic tests for Taenia-specific faecal antigen based on polyclonal rabbit antisera against Taenia saginata or Taenia solium proglottid extracts in capture-type ELISA assays have been developed. Taenia-specific antigen was detected in detergent-solubilized faecal extracts from T. solium- and T. saginata-infected hosts. Coproantigen from T. solium-infected hamsters did not cross-react with faeces from rodents infected with Hymenolepis diminuta, H. citelli, H. micro-stoma, Necator americanus, Strongyloides ratti or Nematospiroides dubius and faeces from uninfected animals. When the T. saginata-capture ELISA was tested with faecal samples positive for T. solium antigen, no cross-reactions were obtained. However, faecal samples from humans infected with T. solium or T. saginata, including some with extremely low egg counts, were cross-reactive by either test. Nevertheless, considerably higher O.D. values were obtained with stool samples from Taenia patients compared to Hymenolepis nana-infected or uninfected individuals. Two individuals, infected with Taenia sp. and positive for coproantigens by ELISA, became antigen-negative 6 days after treatment with Niclosamide. The possibility of developing species-specific immunodiagnostic tests for human taeniasis through coproantigen detection is discussed.
Numerical taxonomy of Trypanozoon based on polymorphisms in a reduced range of enzymes
Authors: Stevens J. R. , Godfrey D. G. 
Published: June 2009

SUMMARYNumerical analyses of Trypanozoon taxonomy are presented, based on the isoenzyme data of Stevens et al. (1992). The previous study used a reduced range of enzymes compared with earlier work; the analyses indicate the value of this rationalized system. Both recently isolated trypanosome stocks and previously studied populations were included, allowing detailed comparison with earlier studies. Relationships between zymodemes were calculated with an improved similarity coefficient program, using Jaccard's coefficient (1908), and by Nei's method (1972). Dendrograms were constructed from the matrices produced with the group-average method. The groupings produced by both numerical methods were in close agreement, and the clusters of related principal zymodemes largely matched the species, subspecies and strain groups proposed by previous workers. Trypanozoon biochemical taxonomy is reviewed and the groupings reinforced by this study are: the mainly East African strain groups, busoga, zambezi, kakumbi, kiboko and sindo; T.b. gambiense and the bouaflé strain group from West Africa, and T. evansi; an intermediate bouaflé/busoga group was also recognized.
Integration and expression of murine retrovirus-related sequences in schistosomes
Authors: Tanaka M. , Iwamura Y. , Amanuma H. , Irie Y. , Watanabe M. , Watanabe T. , Uchiyama Y. , Yasuraoka K. 
Published: June 2009

SUMMARYAntibodies against the retrovirus envelope glycoprotien (gp70) of mouse xenotropic retrovirus, BALB virus 2 (Bv2) reacted with the adult worms ofSchistosoma japonicumandS. mansoni. This reaction was completely inhibited after adsorption of the antibodies with virions of retrovirus. The reactive schistosome antigen was located in the subtegumental layer of the adult male fluke and in the vitelline gland of the adult female ofS. japonicumandS. mansoni. Proteins extracted from both parasites were examined by immunoblot analysis. Anti-Bv2 gp70 antiserum reacted with those proteins from both schistosomes and the band patterns were different among sexes and species. Southern hybridization of the DNA extracted from adults ofS. japonicumandS. mansonidemonstrated the presence of sequences homologous to theenvgene of mouse ecotropic and xenotropic retroviruses. DNA sequences homologous to thegagandpolregions of the ecotropic murine leukaemia virus were also detected in the DNAs of schistosomes
On the interpretation of age—prevalence curves for schistosome infections of host snails
Authors: Woolhouse M. E. J. 
Published: June 2009

SUMMARYThe prevalence of schistosome infections in intermediate host snails varies with snail age. The relationship between age and prevalence, the age—prevalence curve, is complex and may vary in space and time, and among parasite—host species. Field studies show that the shape of the age—prevalence curve may be seasonally variable, and that at some times there may be a decline in prevalence among older snails. This paper attempts to explain these observations in terms of the underlying epidemiological processes. A discrete-time version of Muench's catalytic model for age-dependent infection is developed. Model simulations were carried out using life-history and epidemiological parameters derived from studies ofSchistosoma haematobium—Bulinus globususin Zimbabwe. Analysis of model behaviour identifies aspects of the schistosome— snail interaction that affect the shape of the age—prevalence curve. The following features can result in a decline in prevalence among older snails. (1) A decrease in the survival rate of patent infected snails with age. (2) A decrease in the force of infection with age. (3) A high rate of loss of infection. (4) A heterogeneity in the snail population such that the probability of infection is correlated with snail fecundity. (This would occur if there existed a spatial correlation between force of infection and fecundity, or if there were a correlation between fecundity and susceptibility.) The evidence for the occurrence of these features in the field is assessed. Survival rate is related more closely to the duration of patent infection than to ageper se. The evidence for age-dependent force of infection is equivocal. Significant loss-of-infection rates have yet to be demonstrated. Heterogeneities in force of infection and fecundity have been reported and, for the Zimbabwe data, this mechanism can explain seasonally in the age—prevalence curve as a function of known seasonal variation in the force of infection and snail fecundity.
Infectivity of Trichinella isolates in mice is determined by host immune responsiveness
Authors: Bolas-Fernandez F. , Wakelin D. 
Published: June 2009

SUMMARYA comparison was made of the development, survival and reproduction of 5 isolates of Trichinella spiralis in inbred mice. Low responder C57BL/10 mice allowed worms of all isolates to survive longer and reproduce more successfully than did high responder NIH mice, suggesting that host immunity exerted a dominant influence upon infectivity. One isolate (Is-5 (W) — an arctic isolate) had a markedly lower infectivity than all other isolates, and was selected for more detailed study, together with isolate Is-1 (S) (a temperate isolate) which showed high infectivity. The lower infectivity of Is-5 (W) reflected a more rapid onset of immunity in mice infected with this parasite, immunity reducing the reproductive potential of female worms and causing an early expulsion from the intestine. No evidence of a dose-dependent suppression of immunity was found to explain the higher infectivity of Is-1 (S). Is-5 (W) provided a very rapid mucosal mastocytosis in infected mice, whereas Is-1 (S) caused no measurable response. In contrast, Is-1 (S) elicited higher levels of circulating parasite-specific antibodies than did Is-5 (W). These results are discussed in relation to the interplay of parasite immunogenicity and host immune responsiveness in determining infectivity, and point to the importance of identifying those immunodominant parasite molecules which control the balance of the host—parasite relationship.
Growth of single proglottides during early adult development of Hymenolepis nana
Authors: Kumazawa H. , Fairweather I. 
Published: June 2009

SUMMARYThe growth of individual proglottides of Hymenolepis nana has been studied by measuring the width and length of the proglottides between days 3 and 8 post-infection in mice. Two sets of measurements were obtained. The first involved proglottides immediately posterior to the point of proglottis formation and proglottides at particular stages of development. For the second set, measurements were made of proglottides at certain positions in the worm, specifically the 20th, 100th and 200th proglottides, as counted from the posterior end of the worm. For proglottides at different stages in development, the width of a particular stage was greater in the later days of infection, while the length was almost constant. The length of newly-formed proglottides varied only slightly with time despite differences in the width and in the 3-fold increase in proglottis production that occurs between days 3 and 8 post-infection. The width of the 20th, 100th and 200th proglottides followed parallel growth curves that coincided with each other after an appropriate shift along the time axis. The more anterior the position of the proglottis, the greater was the width at the time of proglottis formation, and so its growth began later on the common growth curve. Growth in length of the 20th proglottis was at first faster than the 100th and 200th proglottides, but later slowed down to a level comparable with them, and the growth curves for the length of the three proglottides were very similar to each other. The rates of growth in the volume of the three proglottides were also estimated. The results are also discussed in relation to other approaches to the study of tapeworm growth and to factors that may be responsible for the growth patterns observed.
Human host selection by anophelines: no evidence for preferential selection of malaria or microfilariae-infected individuals in a hyperendemic area
Authors: Burkot T. R. , Narara A. , Paru R. , Graves Patricia M. , Garner P. 
Published: June 2009

SUMMARYHost selection among humans by Anopheles punctulatus was studied in an area of Papua New Guinea endemic for malaria and filariasis. Blood films were made from the stomach contents of freshly engorged mosquitoes found resting on the walls of houses in which the parasite status of the occupants was known. Engorgement rates on humans were non-random but could not be consistently related to the parasite status of individuals in the houses for either malaria or filaria. In some households, anophelines preferentially fed on parasitaemic individuals while in other households aparasitaemic individuals were significantly more often selected. This finding is believed to reflect the fact that malaria and filarial infections in this endemic area are predominantly asymptomatic. There were no significant differences in axillary temperatures between malaria or microfilariae positive or negative individuals.
Diversity patterns in helminth communities in common gulls,Larus canus
Authors: Kennedy C. R. , Bakke T. A. 
Published: June 2009

SUMMARYThe parameters of species richness, abundance and diversity of the intestinal helminth infracommunities of a sample of 269 Common gulls,Larus canus, were examined over one season at Agdenes, Norway. The communities developed rapidly in unfledged gulls and the diversity parameters were of similar magnitude in immature and adult birds. All parameters were low in the early part of the season, reached maxima in June or July and fluctuated erratically or declined thereafter. Comparison of summary parameters with those from other species of gulls indicated that helminth community diversity in Common gulls is fairly typical of gulls in general. In gulls as a group, helminth communities show common features of high species richness, low abundance, few or no core species and a number of species that occur rarely and in low numbers. Expectations of particularly high parasite community diversity were not fully realised because species lists and diversity of the component community are not a very good basis for predicting diversity at the infracommunity level.
Preliminary biochemical characterization of ‘veil’ structure purified fromTheileria sergenti-, T. buffeli- andT. orientalis-infected bovine erythrocytes
Authors: Sugimoto C. , Kawazu S. , Sato M. , Kamio T. , Fujisaki K. 
Published: June 2009

SUMMARYA structure called ‘veil’ inTheileria sergenti-, T. buffeli- orT. orientalis-infected bovine erythrocytes was purified from erythrocyte lysates by Percoll density-gradient centrifugation. On electron microscopical examination, the veils consisted of electron-dense material showing a periodicity of striations and were not surrounded by membranes. Analyses of veil proteins by one- and two-dimensional polyacrylamide gel electrophoresis revealed that the veils contain haemoglobin and several other basic proteins of molecular weight ranging from 15·5 to 46 kDa. By comparing the protein patterns of the veil with those of purified piroplasms and uninfected bovine erythrocytes, these basic proteins appeared to be of parasite origin. It would appear likely that the veils formed by intra-erythrocytic precipitation of haemoglobin and proteins excreted by the parasites. Differences in veil constituents were found betweenT. sergenti, T. buffeliandT. orientalis.
Relationship between body size of adult Anopheles gambiae s.l. and infection with the malaria parasite Plasmodium falciparum
Authors: Lyimo E. O. , Koella J. C. 
Published: June 2009

SUMMARYThe influence of adult female body size of Anopheles gambiae s.l. on development of midgut and salivary gland infections by the parasite Plasmodium falciparum was investigated in a field study carried out in Tanzania. The proportion of mosquitoes infected during a blood meal was independent of size. However, the number of oocysts harboured by infected mosquitoes increased with size of the mosquito. The proportion of mosquitoes with sporozoites, and thus potentially infective to humans, was highest in intermediate-sized mosquitoes, whereas the largest and smallest mosquitoes were less likely to have sporozoites. This pattern is interpreted as a combination of high survival rate of large, uninfected mosquitoes and of low survival rate of mosquitoes infected with many oocysts.
The effect of repeated chemotherapy on age-related predisposition to Ascaris lumbricoides and Trichuris trichiura
Authors: Chan L. , Kan S. P. , Bundy D. A. P. 
Published: June 2009

SUMMARYThis study examines the persistence of predisposition to Ascaris lumbricoides and Trichuris trichiura during repeated chemotherapy in an urban community in Kuala Lumpur, Malaysia. Significant predisposition was observed over 2 periods of reinfection with and without age-standardization of data. Analysis of different age groups indicated that predisposition was most strongly detectable in the younger age classes. The intensities of infection with both parasites were strongly correlated at each cycle of intervention, suggesting that individuals were similarly predisposed to both species.
Schistosoma mansoni: the ultrastructure of the ducts of the male reproductive system.
Authors: Otubanjo Olubunmi A. 
Published: June 2009

SUMMARYThe reproductive duct of the male blood fluke Schistosoma mansoni is relatively short and undulating, extending from the most posterior testis to the beginning of the gynecophoric canal. The reproductive duct may be divided into 3 main regions which differ in ultrastructure; the vas efferens/deferens, the seminal vesicle and the cirrus tube. The epithelium of the vas efferens/deferens consists of a single layer of elongate cells with abundant convoluted lamellae on their apical surfaces. The wall of the seminal vesicle and the cirrus tube are tegumentary in nature. The basic similarities in structure of the surface tegument, the seminal vesicle and the cirrus tube suggest a common embryological origin. The presence of complex lamellae on the luminal surface suggests that the vas efferens and deferens have secretory and possibly nutritive functions apart from temporarily storing developing germ cells. The primary function of the seminal vesicle appears to be that of sperm storage; while the cirrus tube with its complex infolded wall is extensible for insemination. The presence of abundant concentrically distributed sensory papillae around the male genital pore may assist in the pairing of males and females.