bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunological relationships during primary infection with Heligmosomoides polygyrus (Nematospiroides dubius): the capacity of adult worms to survive following transplantation to recipient mice
Authors: Behnke J. M. , Williams Diane J. , Hannah J. , Pritchard D. I. 
Published: June 2009

SUMMARYChronic primary infections with Heligmosomoides polygyrus (Nematospiroides dubius) are still relatively poorly documented, particularly in relation to the role of host resistance in limiting worm survival. In the present work the duration of infection with H. polygyrus was studied in CFLP mice given doses of infective larvae ranging from 50 to 500 L3. The least heavily infected (50 L3) group ceased egg production earliest (week 36) whereas eggs were still detected in the faeces of mice given 500 larvae in week 42. At autopsy (week 42) mice given 50 larvae had virtually lost their entire worm burden with 5 out of 11 mice still harbouring a single worm each. However, all the mice in the group given 500 larvae were still infected, the highest worm burden being 93. The concentration of serum IgGl and specific antibody was highest in mice given 500 larvae, but sera taken from mice with declining worm burdens 19–38 weeks post-infection did not contain detectable host-protective antibody. During the course of infection in CFLP mice, H, polygyrus sustained irreversible changes in its capacity for subsequent survival. Thus, adult worms transferred to naive mice 2, 7, 14, 30 or 36 weeks post-infection did not live longer than worms of a comparable age in the respective donor group. In contrast, primary infection worms taken from jirds in which expulsion is usually completed by 6 weeks post-infection, re-established in mice and survived considerably longer than in the group of donor jirds. These results were discussed in relation to the possible interactions between parasite senility and immunomodulation, and host resistance in limiting primary infections with H. polygyrus in mice and jirds.
Use of75Se tracer and autoradiographic techniques in the study of schistosomiasis
Authors: Chandiwana S. K. 
Published: June 2009

SummaryThe paper provides an overview of recent studies on the use of75Se to tag larval schistosomes and to monitor their migration and distribution patterns in naive mice and those previously exposed to cercariae. The principles and techniques of radioassay and autoradiography in studying various aspects of75Se-labelled larval schistosomes are described. The main shortcoming of radioassay in monitoring location and movement of labelled schistosomula is that some of the label dissociates from the schistosomula and accumulates in host tissues, notably the liver. Dissociated label is indistinguishable from schistosomula-bound label making monitoring of parasite migration extremely difficult. This difficulty is overcome by compressed tissue autoradiography where labelled schistosomula can be seen as reduced silver foci on an autoradiographic film, whereas dissociated label is too diffusely distributed to produce such reduced silver foci. Furthermore, using autoradiography, quantitative information on parasite migration in normal and immunized laboratory animals can be obtained that would be impossible using traditional recovery techniques. In addition to using75Se tracer in migration studies, the radio-isotope has potential for elucidating various aspects of schistosome transmission ecology and snail population dynamics in natural waters.
The effects of oxytetracycline onTheileria parva in vitro
Authors: Spooner P. R. 
Published: June 2009

SummaryWhen bovine peripheral blood leucocytes were infected withTheileria parvasporozoites, immediate treatment with oxytetracycline (OTC) inhibited the development of sporozoites to mature schizonts. The extent of inhibition was dependent on drug concentration and duration of treatment. Concentrations of 5μg/ml OTC, or higher, for 8 days completely inhibited the establishment of schizonts and their ability to transform host cells. A cytostatic effect on schizont-infected cell lines was found with three tetracyclines and was also demonstrated on uninfected lymphoblasts. The parasites were found to be sensitive t OTC during development to schizonts, but when mature and established within host cells, schizonts were not demonstrably affected. The infectivity of sporozoites and the binding of sporozoites to lymphocytes were not directly inhibited by OTC. The results may explain the action of tetracyclines when used prophylactically during immunization against East Coast fever, and also the reasons for the ineffectiveness of these drugs when used therapeutically during patent disease.
Mitochondria of mammalianPlasmodiumspp.
Authors: Fry M. , Beesley J. E. 
Published: June 2009

SUMMARYHighly purified mitochondrial fractions have been isolated from the intraerythrocytic stages of two mammalianPlasmodiumspp.,Plasmodium yoeliiof rodents andPlasmodium falciparumof man. Mitochondria of the former parasite are cristate whereas those of the latter are essentially acristate. Isolated mitochondria from both parasite species were heterogeneous with respect to size, shape, density of matrix staining and extent of internal structure. Respiratory assay, by reduction of exogenous cytochromec, showed NADH, α-glycerophosphate and succinate to be the substrates with the greatest potential for metabolism. Additionally, proline, dihydroorotate and glutamate (P. falciparumonly) were oxidized at low rates. A number of NAD+-linked substrates were not utilized. The NADH-dependent reduction of cytochromecwas insensitive to rotenone and antimycin A. Fumarate inhibited the NADH-dependent reduction of cytochromecand stimulated the oxidation of NADH, suggestive of an NADH–fumarate reductase pathway. Oxidation of either α-glycerophosphate or succinate was fully inhibited by standard mitochondrial electron transport inhibitors, including a number of Complex III inhibitors, although the concentrations required of such inhibitors (notably myxothiazol) were relatively high compared to mammalian mitochondria. Dithionite-reduced minus oxidized difference spectra indicated the presence of cytochromesaa3,b, candc1in mitochondria of both parasite species, but at a higher cytochrome to protein ratio inP. yoelii. Freshly isolated mitochondria from either species exhibited only low respiratory control ratios with α-glycerophosphate or succinate as substrates. The apparent absence of a respiratory chain ‘Site I’ in such mitochondria may mean that NADH–fumarate reductase serves to reoxidize mitochondrial NADH.
Activated macrophages in highly irradiated cercariae-induced immunity toSchistosoma japonicumin rats
Authors: Xu C. , Xu S. 
Published: June 2009

SUMMARYThe results of studies on the schistosomulicidal activity of activated peritoneal and alveolar macrophages (pMø and aMø) from rats immunized with highly irradiated (50 krad.)Schistosoma japonicumcercariae are reported. The authors have examined the activation of these macrophages in terms of spreading, adhesion and ingestion of sheep erythrocytes and pinocytosis of horse-radish peroxidase. Using three criteria, peritoneal macrophages and alveolar macrophages from immunized rats and from rats intraperitoneally injected with BCG were significantly more active than those from normal rats or rats stimulated with 10% proteose-peptone or 1% sodium thioglycolate. A significantly higher percentage of adhesion and ingestion was obtained with the sheep erythrocytes that were co-opsonized by heat-inactivated rat anti-sheep erythrocyte serum and fresh normal rat serum. Schistosomulicidal effects were observed with macrophages from irradiated cercariae-immunized rats in two activation systems:in vitroactivation in the presence of macrophage-activating factor (MAF), andin vivoactivation by the intraperitoneal challenge with sonicated cercarial antigens.
Trichobilharzia ocellata: influence of infection on the fecundity of its intermediate snail host Lymnaea stagnalis and cercarial induction of the release of schistosomin, a snail neuropeptide antagonizing female gonadotropic hormones
Authors: Schallig H. D. F. H. , Sassen M. J. M. , Hordijk P. L. , De Jong-Brink M. 
Published: June 2009

SUMMARYSubadult and adult specimens of the pond snail Lymnaea stagnalis were infected with the schistosome Trichobilharzia ocellata. Egg production and growth of the snails were monitored over an 8-week period post-infection (p.i.). Snail haemolymph was collected and analysed for the presence of schistosomin, a neuropeptide which antagonizes the action of the snails' female gonadotropic hormones. Snails infected as subadults showed an increase in fecundity during the first 4 weeks p.i. compared with non-infected controls. The possibility is discussed that this increase is caused by an accelerated maturation of the female sex organs due to elevated levels of Dorsal Body Hormone, a female gonadotropic hormone. No difference in fecundity was found between snails infected as adults and control snails during the first 4 weeks p.i. Snails infected as subadults and as adults showed a decrease in fecundity from week 5 p.i. and onwards. This decrease coincided with the appearance of schistosomin in the haemolymph of the snails and with that of differentiating cercariae in the daughter sporocysts. Cercariae are probably involved in the induction of schistosomin release from the snails' CNS into the haemolymph. Snails infected as subadults or as adults grew at approximately the same rate as uninfected snails.
Spermatogenesis and the fine structure of the mature spermatozoon of the liver fluke, Fasciola hepatica (Trematoda: Digenea)
Authors: Stitt A. W. , Fairweather I. 
Published: June 2009

SUMMARYSpermatogenesis and the fine structure of the mature spermatozoon of Fasciola hepatica have been studied by transmission electron microscopy. The primary spermatogonia display a typical gonial morphology and occupy the periphery of the testis. They undergo 3 mitotic divisions to give rise to 8 primary spermatocytes forming a rosette of cells connected to a central cytophore. The primary spermatocytes undergo 2 meiotic divisions, resulting in 32 spermatids that develop into spermatozoa. Intranuclear synaptonemal complexes in primary spermatocytes confirm the first meiotic division. The onset of spermiogenesis is marked by the formation of the zone of differentiation which contains 2 basal bodies and a further centriole derivative, the central body. The zone extends away from the spermatid cell to form the median process; into this migrates the differentiated and elongate nucleus. Simultaneously, 2 axonemes develop from the basal bodies. During development, they rotate through 90° to extend parallel to the median process. The migration of the nucleus to the distal end of the median process coincides with the fusion of the axonemes to the latter to form a monopartite spermatozoon. The mature spermatozoon possesses 2 axonemes of the 9 + ‘1’ pattern typical of parasitic platyhelminths, 2 elongate mitochondria and a variable array of peripheral microtubules. The nuclear region of the spermatozoon is immotile. The value of sperm ultrastructure as a taxonomic tool in platyhelminth phylogeny is discussed.
Temporal patterns in the epidemiology of schistosome infections of snails: a model for field data
Authors: Woolhouse M. E. J. , Chandiwana S. K. 
Published: June 2009

SUMMARYThe prevalence of patent schistosome infections of intermediate host snails often shows seasonal variations. For schistosome, mainlySchistosoma haematobium, infections ofBulinus globosusfield data from Zimbabwe show annual ranges in prevalence from 2% to 30%. In this paper a mathematical model is developed for B. globosus population dynamics and the epidemiology of schistosome infection. The model is a discrete-time analogue of a catalytic model, with an added recruitment term. Snail fecundity and survival are functions of age, infection, and temperature. The pre-patent period of infection is dependent on temperature.Parameter values, and relationships with temperature, are taken from earlier field and laboratory studies. The force-of-infection is estimated from analysis of age-prevalence data. Model predictions, making use of temperature data recorded in the field, are in good agreement with observations over a 2-year period at a study site in Zimbabwe. The key features of interest are a fall in the prevalence of patent infections during the cold season and a rapid rise to a peak early in the hot season. This pattern results from the accumulation of pre-patent infections which fail to develop at low temperatures, but mature en masse, together with new infections, after a few weeks at higher temperatures. Model analysis demonstrates that seasonal patterns in the prevalence of patent infections may be due largely to the influence of temperature on the pre-patent period. Seasonal and year-to-year variations in temperature may therefore have significant epidemiological effects.
Major sperm protein and actin genes in free-living and parasitic nematodes
Authors: Scott A. L. , Dinman J. , Sussman D. J. , Ward S. 
Published: June 2009

SUMMARYThe DNA from a number of free-living and parasitic nematode species was examined to determine the genomic number and distribution of DNA sequences encoding two evolutionary conserved proteins; the major sperm protein (MSP) and nematode actin. Ascaris and Caenorhabditis MSP cDNA sequences and Ascaris genomic actin sequences were used to probe Southern blots of Eco RI and Hin d III digested nematode DNA. The number of MSP genes varied widely between the 1 MSP gene in Ascaris and the 60 MSP genes in Caenorhabditis. Filarial nematodes appeared to have 1—4 MSP genes while the plant and insect parasitic species showed from 5–12 MSP-hybridizing restriction fragments. Mammalian intestinal parasites showed between 1 and 13 bands hybridizing with the MSP probes. Blots probed to estimate the number of actin genes showed that, with the exception of Ascaris which contains more than 20 germ line sequences that encode actin, all of the nematodes tested had between 3 and 9 bands that hybridized to the Ascaris genomic actin probe. The possible use of highly conserved sequences such as MSP and actin to differentiate between nematode species in diagnostic and taxonomic studies is discussed.
Age-related differences in parasitosis may indicate acquired immunity against microfilariae in cattle naturally infected with Onchocerca ochengi
Authors: Trees A. J. , Wahl G. , Kläger S. , Renz A. 
Published: June 2009

SUMMARYOnchocerca ochengi is a common parasite of cattle in savanna areas of West Africa and its adult stages inhabit intradermal nodules. We have exploited the accessibility of the macrofilariae to examine quantitative and qualitative differences in both the macro- and microfilariae (mff) in relation to age in naturally infected cattle. Autochthonous cattle at a site on the Adamawa plateau, North Cameroon, situated near a perennial Simulium damnosum s.l. breeding site, were examined in three age groups (1·5–2·5, n = 34; 3–5, n = 39 and ≥ 8 years old, n = 21). Skin mff densities were assessed from ventral skin biopsies, total body counts of nodules were done by palpation and 1–4 nodules were excised from positive animals, collagenase digested and the numbers and condition of macrofilariae determined. Embryogenesis profiles (embryograms) were done on a representative number of female worms in each age group. The overall prevalence of infection in the study population was 71% for mff and 85% for nodules. Nodule prevalence increased significantly from the 1·5–2·5 to 3–5 years old groups, but no other inter-age prevalences were significantly different. While the mean number of nodules per animal increased with age, geometric means (gm) 3·7, 15·5 and 23·1, the skin mff density maximized in the middle age group and decreased significantly in the old animals (gm 15·8, 44·7 and 11·4 mff/g, difference between latter two parameters significant, P < 0·05). Moreover, there was a significant correlation (P < 0·01) between individual nodule counts and skin mff densities in the mid-aged group but not in the oldest group. Examination of nodules showed that nodule counts equated to numbers of female worms, since almost all of 133 nodules examined contained only 1 live female worm. Although the proportion of old female (and male) worms increased with the age groups – 2 (0), 30 (28) and 54 (32)% – the proportion of gravid females (52·8, 48·8 and 58·0%) and the mean number of viable embryos in these females (82·5 × 103, 76·0 × 103 and 102·1 × 103) did not change with age. Thus, due to the higher nodule counts, a calculated productivity index reflecting the potential mff production per animal was 8 times higher in the ≥ 8-year-old animals than in the youngest and 3 times higher than in the middle group, which sharply contrasts with the decline in skin mff density. Although further research is required, these findings may indicate acquired immunity directed against microfilariae. They demonstrate the potential of O. ochengi infections in cattle to investigate a number of aspects of the host–parasite relationship which may have relevance to human onchocerciasis.
Effects of storage time and temperature on amylopectin levels and oocyst production of Eimeria meleagrimitis oocysts
Authors: Augustine P. C. 
Published: June 2009

SUMMARYEimeria meleagrimitis oocysts were stored at 4, 22, 32 or 41·5 °C for up to 1 year. Decreases in amylopectin levels (measured as glucose) and viability (measured as oocyst production and mortality in turkeys) of the oocysts were generally related to the length of time in storage and the storage temperature. Oocysts assayed immediately after harvest contained 58·29 ± 0·75 μg of glucose/106 oocysts. When the oocysts were stored at 4 °C for 162 days, the amylopectin level decreased to 65% of the original level. In oocysts stored at 22, 32 and 41·5 °C, amylopectin declined to approximately 20% within 162, 76, and 41 days, respectively. Oocysts stored at 4 °C for 1 year produced more oocysts in turkeys than the original fresh isolate, but caused no mortality. Oocyst production from oocysts stored at 22 and 32°C decreased gradually until, after 9 and 7 months respectively, no patent infections were produced. Oocyst production from oocysts stored at 41·5 °C was markedly reduced within 1 month and was not detected after 4 months.
Eimeria necatrix: the development and characteristics of an egg-adapted (attenuated) line
Authors: Shirley M. W. 
Published: June 2009

SUMMARYSporozoites of Eimeria necatrix inoculated into the allantoic cavities of embryonating eggs completed their life-cycle in the chorio-allantoic membranes and produced fully viable oocysts. Subsequently, as a result of repeated passage in this host, an egg-adapted line was developed and was found to be markedly less pathogenic for chickens than the nonpassaged parent strain. Antigens capable of inducing protective immunity against challenge with low doses of the parent strain were retained, however, indicating a possible use for this egg-adapted (attenuated) line of E. necatrix in the immunization of comercially reared chickens.
Strain variation within Eimeria meleagrimitis from the turkey
Authors: Long P. L. , Millard B. J. , Shirley M. W. 
Published: June 2009

During the course of a field study of coccidiosis in turkeys, Eimeria oocysts were found which had much smaller dimensions than any previously recorded isolate from the turkey. These oocysts were purified by single oocyst infection of a turkey. The first oocysts (mean dimensions 16.15 ×14.75 μm) were recovered 103 h later. Inoculation of between 0·5 and 2.5 ×105 oocysts of this isolate caused severe effects on body weight gain. Cross-immunity studies showed the parasite to be a strain of E. meleagrimitis. Electrophoretic analyses of two enzymes showed that the strain could be differentiated from another strain of E. meleagrimitis. (Weybridge strain B).The results show that strain variation occurs within the species E. meleagrimitis and extreme caution should be used in identifying species of Eimeria from the turkey by their oocyst characters.
The inheritance of enzyme variants of glutamic-oxaloacetic transaminase in Paragonimus ohirai
Authors: Agatsuma Takeshi , Habe Shigehisa 
Published: June 2009

SUMMARYLung flukes, Paragonimus ohirai, from Kinosaki, Japan, characterized by 3 electrophoretic variants, FF, FS and SS, of glutamic-oxaloacetic transaminase (GOT: EC 2.6.1.1) were crossed in the laboratory. In the case of a cross between FS and SS, a parent, FS, produced 9 SS and 16 FS clones in the offspring, numbers not significantly different from that expected (1:1) from Mendelian inheritance. From the other cross FS × FF, 20 clones originating from the respective 20 miracidia were obtained from a parent FS. The phenotype segregation ratio was 6 FF and 14 FS, which is not significantly different from Mendelian inheritance expectation. Only 3 clones were obtained from the other parent FF, but these segregated in a ratio of 2 FS: 1 FF. These breeding data indicate that the GOT isozymes of P. ohirai are controlled by 2 codominant alleles, GotF and Gots at a single locus whose products aggregate randomly, forming a dimer.
Mitochondrial DNA andAscarismicroepidemiology: the composition of parasite populations from individual hosts, families and villages
Authors: Anderson T. J. C. , Romero-Abal M. E. , Jaenike J. 
Published: June 2009

SUMMARYPatterns of genetic subdivision in parasite populations can provide important insights into transmission processes and complement information obtained using traditional epidemiological techniques. We describe mitochondrial sequence variation in 265Ascariscollected from 62 individual hosts (humans and pigs) from 35 households in 3 Guatemalan locations. Restriction mapping of individual worms revealed 42 distinct mitochondrial genotypes. We ask whether the mitochondrial genotypes found in worms from individual hosts, from families of hosts and from villages represent random samples from the totalAscarispopulation. Patterns of genetic subdivision were quantified using F-statistics, while deviations from the null hypothesis of randomness were evaluated by a simple resampling procedure. The analysis revealed significant deviations from panmixia. Parasite populations were strongly structured at the level of the individual host in both humans and pigs: parasites bearing the same mitochondrial genotype were found more frequently than would be expected by chance within hosts. Significant heterogeneity was also observed among populations from different villages, but not from different families within a village. The clustering of related parasites within hosts suggests a similar clustering of related infective stages in the environment and may explain why sex ratios inAscarisare female-biased. We discuss aspects ofAscarisbiology which may lead to the observed patterns.
The migration of infective larvae of Brugia pahangi within the mosquito, Aedes aegypti
Authors: Lindsay S. W. 
Published: June 2009

SUMMARYThe course of the migration of infective larvae of Brugiapahangi within the mosquito, Aedes aegypti, is described. The presence of blood or eggs in the abdomens of mosquitoes at a time when the infective larvae are beginning their migration out of the thorax leads to a significant increase in the proportion of larvae accumulating in the abdomen. The evidence supports the hypothesis that infective larvae may accumulate in the labium as a direct consequence of the insect's internal anatomy i.e. infective larvae on moving into a confined space tend to remain there. In addition, the rate at which infective larvae migrate into the labium is shown to be density dependent.