bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hymenolepis diminuta: the mechanism of egg hatching
Authors: Holmes S. D. , Fairweather I. 
Published: June 2009

SUMMARYThe fine structure and histochemistry of the envelopes surrounding the mature oncosphere of Hymenolepis diminuta have been investigated by transmission electron microscopy and light microscope observations of JB-4 embedded material. The fate of these envelopes during the hatching sequence in vitro has been followed by phase-contrast and scanning electron microscopy. Hatching is considered to comprise 4 stages. Stage 1 involves the mechanical breakage and removal of the shell and the outer cytoplasmic layer of the inner envelope; Stage 2 the activation of the oncosphere and the swelling of the gelatinous layer of the inner envelope; and Stage 3 the digestion and rupture of the embryophore. This is accomplished both by secretions from the penetration gland and by the action of external digestive enzymes, together with hook activity. Trypsin is more effective than amylase in digesting the embryophore. Stage 4 involves the enzymatic weakening of the gelatinous layer which helps the oncosphere to tear itself free with its hooks. Amylase is more effective than trypsin in attacking the gelatinous layer. On emergence from the gelatinous layer, the oncosphere is still enveloped by the ‘oncospheral membrane’, although this covering is soon lost. Once activated, the oncosphere is capable of completing the hatching sequence by itself, without the addition of enzymes. This process is a lengthy one, however, taking up to 2 h, and the expenditure of its glandular and energy reserves makes successful gut penetration by the oncosphere unlikely.
The use of faecal egg counts for estimating worm burdens in sheep infected with Haemonchus contortus
Authors: Coadwell W. J. , Ward P. F. V. 
Published: June 2009

SUMMARYClun forest sheep, worm-free from birth, were given a single dose of 20000 infective larvae of Haemonchus contortus. The total number of eggs/day in the faeces was recorded for 21 infections and data on population size, sex ratio and individual worm development were collected from 76 sheep. The female to male ratio was 1·28±0·07 (s.E.). The relation between increase in worm size and uterine egg content was linear. The number of eggs present in the uteri was found to be an accurate measure of eggs passed. It was shown that the daily faecal egg output is related to total parasite weight and is not a measure of the number of individuals present.
Scanning electron microscopic study of the tegumental surface of adult Schistosoma mekongi
Authors: Vongpayabal P. , Sobhon P. , Upatham E. S. , Wanichanon C. , Mitranond V. , Tanphaichitr N. , Tumbel V. E. C. 
Published: June 2009

SUMMARYThe surface topography of the tegument of adult Schistosoma mekongi was studied by scanning electron microscopy (SEM). In comparison to other species of human schistosomes the male tegument lacks tubercles and, except in the gynecophoral canal, also lacks spines; instead the surface is composed chiefly of trabeculae of highly perforated ridges which give it the ‘spongy’ appearance. In addition, there are 3 kinds of papillae interspersed on the surface among the ridges. The first is a doughnut-shaped papilla with a central crater which is most abundant on the ventral surface of the anterior part, on the floor of the gynecophoral canal and on the dorsal-lateral aspect of the tail. The second is a pleomorphic papilla with irregular shape and size, which is scattered throughout the dorso-lateral aspect of the middle part of the body. The third type of papilla has a uniform hemispherical shape, possesses a cilium projecting from its apex and probably corresponds to the ‘sensory papilla’ found in other species. The tegument of the female differs from that of the male by having numerous short spines over the whole surface; however, the pleomorphic papillae are much fewer in number and the ridges are much less developed than those of the male tegument; complex trabeculae are absent.
Schistosoma mansoni: scanning electron microscopy of schistosomula, adults and eggs grown in vitro
Authors: Basch P. F. , Basch Natalicia 
Published: June 2009

SUMMARYDevelopment of surface topography of cultured Schistosoma mansoni was followed in the cercariae, newly transformed and older schistosomula, and adults. Comparison with surface features of schistosomes from animal infections revealed no apparent differences in tegumental folding or morphogenesis, spines, sensory structures, or other components. Eggs produced by worm pairs grown in vitro were grossly abnormal, usually composed of loosely packed vitelline granules and lacking a shell.
Studies with Eimeria acervulina and E. mivati: pathogenicity and cross-immunity
Authors: Norton C. C. , Joyner L. P. 
Published: June 2009

SUMMARYPathogenic effects caused by graded doses of recent isolates of Eimeria acervulina, E. mivati and a new isolate, thought at first to be E. mitis, were compared. Cross-immunity studies were conducted with 3 strains of E. acervulina and 2 strains of E. mivati, together with the new isolate. The results showed marked similarities between E. mivati and the new isolate and clear distinctions between these and E. acervulina. E. mivati produced scattered petechiae but did not form discrete lesions in the intestine comparable to those seen with E. acervulina. Endogenous stages of E. mivati were most numerous in the lower small intestine and proximal caeca. The ratio of villus height to total mucosal thickness in the lower intestine was reduced. Similar changes caused by E. acervulina were seen in the anterior intestine only.
Passive transfer of resistance and the site of immune-dependent elimination of the challenge infection in rats vaccinated with highly irradiated cercarie ofSchistosoma mansoni
Authors: Ford M. J. , Bickle Q. D. , Taylor M. G. , Andrews B. J. 
Published: June 2009

SUMMARYThe immune-dependent elimination of a challenge infection in rats vaccinated with highly-irradiated cercarriae ofSchistosoma mansoniwas analysed by passive transfer of serum, recovery of the challenge from the lungs and liver and by transferring lung-stage schistosomula. Recipients of serum from rats immunized with either unirradiated, 20 or 40 krad.irradiated cercariae, most of which die in the liver, lungs and skin, respectively, were equally resistant if the serum was injected on the day of infection or 5–7 days after infection. In addition, vaccinated rat serum transferred to mice and vaccinated rabbit serum transferred to rats conferred comparable protection when injected on day 0 or 5 days after infection of the recipents. This apparent susceptibility of the lung schistosomula to immune attack was confirmed by challenging 20 or 40 krad.-irradiated cercariae vaccinated rats with lung-stage schistosomula derived either from mice or rats. All the detectable attrition of a cercarial challenge in vaccinated rats occurred between 7 and 10 days post-challenge, before the parasites reached the liver. Since there was no evidence of damage or attrition in the skin or lungs before day 7 it was concluted that immune-dependent elimination occurred rapidly following a ‘window of sensitivity’ coinciding with the migration of the parasites from the lungs to the liver.
Studies on the pathophysiology of chronic ovine haemonchosis in Merino and Scottish Blackface lambs
Authors: Abbott E. M. , Parkins J. J. , Holmes P. H. 
Published: June 2009

SUMMARYAn experiment was conducted to examine, under laboratory conditions, the pathophysiology of chronic ovine haemonchosis. In the present study, groups of Merino and Scottish Blackface lambs were maintained on a low plane of nutrition and infected with 50 Haemonchus contortus larvae/kg live weight. The parasitized lambs along with respective breed controls were examined over a 27-week period. In addition to the body weight, haematological and parasitological parameters, erythrokinetic, metabolic, digestibility and nitrogen balance studies were conducted in the early stages of the infection. The results demonstrated that a low level of infection with H. contortus in lambs on a poor plane of nutrition caused the development of a normochromic normocytic anaemia which was associated with a modest but significant increase in abomasal blood loss and slightly elevated erythropoiesis in both breeds relative to the controls. The level of anaemia, hypoproteinaemia and pathophysiological changes were more marked in the Merino lambs and they also had higher faecal egg counts than the Blackface lambs.
An ultrastructural study of developing stages of exo-erythrocytic Plasmodium berghei in rat hepatocytes
Authors: Meis J. F. G. M. , Verhave J. P. , Jap P. H. K. , Hess F. , Meuwissen J. H. E. T. 
Published: June 2009

SUMMARYThe ultrastructure of immature exo-erythrocytic forms of Plasmodium berghei in rat hepatocytes was studied at stages between 25 and 51 h of development. A new method was successfully applied to localize the parasites in a small portion of the liver by temporary ligature of blood vessels to the majority of the liver, and from the spleen and the pancreas. Nuclear profiles appeared to be part of a highly lobed nuclear reticulum. Peripheral vesiculation and vacuolization of the cytoplasm was increasingly prominent and ushered in the formation of pseudocytomeres. Spacing between host- and parasite-derived membranes could first be observed after 43 h of development. In general, organellar development was found to follow closely that described for plasmodial oocysts.
The influence of the H-2 complex on responses to infection bySchistosoma mansoniin mice
Authors: Jones Janet T. , Mccaffery D. M. , Kusel J. R. 
Published: June 2009

SUMMARYIn order to determine whether a given H-2 haplotype has similar effects on responses to schistosomiasis mansoni on different genetic backgrounds, mice of 2 pairs of congenic strains (H-2band H-2kon BALB/c and C57BL/10 backgrounds) were infected. Worm burdens, mortality, splenomegaly, tissue and faecal egg counts, and antibody titres to worm and egg antigens were measured. The genetic background had a major effect on the genesis of splenomegaly, on the deposition of eggs in the spleen, the maximum faecal egg count, the antibody titre to egg and worm antigens and the rate of generation of antibody response. The H-2 haplotype was shown to consistently influence the maximum faecal egg count and the antibody titres. Worm burden was not influenced by genetic differences between strains and mortality differences were not significant. The data presented here indicate that the effect of the major histocompatibility complex on responses to infection is greatly influenced by the genetic background on which it is expressed.
Feeding behaviour ofGlossina morsitans morsitansinfected withTrypanosoma vivax, T. congolenseorT. brucei
Authors: Moloo S. K. 
Published: June 2009

SUMMARYThe feeding behaviour ofGlossina morsitans morsitansinfected withTrypanosoma vivax, T. congolenseorT. bruceiwas studied and compared with that of uninfected control tsetse. The following parameters were measured. (1) Mean number of feeds taken in 20 consecutive days; (2) mean rate of blood meal intake in μg/sec of the total days fed; (3) mean weight of blood meal intake/day of the total days fed; (4) mean total blood meal engorgement in 20 days; (5) mean number of probes/day of the days fed; (6) mean frequency of the multiple probe feeds and (7) mean number of pre-feeding probes of the multiple probe feeds. Evidence was found to suggest that the rosettes ofT. vivaxandT. congolensein the proboscis, and colonies ofT. bruceiparasites in the salivary glands, did not significantly alter the feeding behaviour of the vector.
The impact of host nutrition on gastrointestinal helminth populations
Authors: Bundy D. A. P. , Golden M. H. N. 
Published: June 2009

SUMMARYMalnutrition and helminth infection are amongst the most prevalent chronic conditions affecting human health globally. It is estimated that parasitic helminths infect more than 1 billion people, and that more than 2 million clinical cases occur each year (Peters, 1978; Walsh, 1984). Estimates of the incidence of clinical malnutrition suggest that between 5 and 8 million cases occur annually. In many parts of the developing world malnutrition and infection conjointly are the most serious health problem in children, acting as primary or more often as secondary factors in mortality (Puffer & Serrano, 1973). The impact on health is exacerbated because both conditions are chronic, are most common in growing children and, most importantly, tend to occur together in the same individuals (Pawlowski, 1984; Chandra & Newberne, 1977).
Echinococcus granulosus: the effects of praziquantel, in vivo and in vitro, on the ultrastructure of equine strain murine cysts
Authors: Richards K. Sylvia , Morris D. L. , Daniels D. , Riley E. M. 
Published: June 2009

SummaryPraziquantel (500 mg/kg) administered orally to BALB/c mice with secondary equine E. granulosus daily for 21, 30 or 30 + 30 days without the drug resulted in the majority of cysts, using bench criteria of turgidity and eosin exclusion, being assessed as ‘alive’. Ultrastructural examination of 54 of these ‘alive’ cysts did not support this conclusion. They all showed increased vesiculation of the germinal layer leading, in many, to the loss of its integrity. Increased mitochondrial numbers occurred frequently. The longer drug treatments appeared to have greater effects on the germinal layer of ‘alive’ cysts and there was no detectable re-establishment of structural organization within 30 days after drug withdrawal. Subjectively, there was no substantial difference between cysts from 4-month and 9-month infections or between affected peritoneal and hepatic cysts. Tissue from collapsed cysts was necrotic. Peak serum levels of praziquantel (6430–6136 μg/l) occurred 5–10 min after drug administration (500 mg/kg) and dropped rapidly to less than 10 μg/l at 3 h. In an in vitro study at praziquantel concentrations of 1000 and 5000 μg/l over a 10-day period, most cysts were judged ‘alive’ by bench criteria but showed ultrastructurally a time- and concentration-dependent loss of integrity identical to that seen in vivo. Turgidity and eosin exclusion therefore underestimate the effect of praziquantel and the results indicate that in vitro experiments can fulfil a legitimate preliminary role in a hydatid chemotherapy programme.
Evidence for population self-regulation, reproductive competition and arrhenotoky in a thelastomatid nematode of cockroaches
Authors: Zervos S. 
Published: June 2009

SummaryExperimental infection of adultDrymaplaneta variegataShelford, 1909 (Blattodea) with known numbers of eggs ofProtrellus dixoniZervos, 1987 (Nematoda: Thelastomatidae) showed that each infrapopulation was regulated by a density-dependent and sex-dependent reduction in infection intensity with infrapopulation age. This reduction was not equal in initial speed or intensity between the sexes (reduction in number of males was faster) and led to infrapopulations with never more than a single adult male, 1–8 (usually 1–3) adult females and 0–28 juvenile females. In structure, these laboratory-produced infrapopulations resembled those in field-collected hosts. Parasite-mediated chemical interference competition is suggested as the cause of infrapopulation regulation.Per capitaegg production was greater in uncrowded worms which suggests that self-regulation benefits those nematodes that survive competition. Unmated females produced male offspring only (probably by arrhenotokous parthenogenesis). Only females that occurred with a male produced females although some also produced males; such females may avoid insemination or prevent fertilization of some or all eggs. Female offspring probably result from amphimixis.
Immunization of cattle using varying infective doses of Theileria parva lawrencei sporozoites derived from an African buffalo (Syncerus caffer) and treatment with buparvaquone
Authors: Mutugi J. J. , Young A. S. , Maritim A. C. , Linyonyi A. , Mbogo S. K. , Leitch B. L. 
Published: June 2009

SummaryA Theileria parva lawrencei isolate in the form of a sporozoite stabilate, derived by feeding clean Rhipicephalus appendiculatus nymphal ticks on an African buffalo (Syncerus caffer) captured in the Laikipia District, Kenya, was inoculated into groups of cattle at dilutions between 100 and 10-3. Groups of 3 cattle infected with 1 ml inocula at 100, 10-1 and 10-2 dilutions were treated with 2·5 mg/kg body weight of buparvaquone on day 0 and similar groups were left untreated to act as controls. An additional group, given 100 dilution of the stabilate, was treated with buparvaquone on day 8 post-inoculation. It was found that all control cattle inoculated with the stabilate at dilutions between 100 and 10-2 became infected, but only 2 out of 3 cattle developed patent infections at 10-3 dilution. All 3 control cattle receiving 100 dilution died of theileriosis, 2 at 10-1 and 10-2 dilutions, and 1 at 10-3 dilution died. Buparvaquone treatment on day 0 at 100 dilution resulted in the survival of 2 of 3 cattle and all the cattle at 10-1 and 10-2 dilutions. All the surviving cattle eventually developed a significant serological response against T. parva in the indirect fluorescent antibody test, except 1 in the 10-3 dilution group, and were immune to homologous challenge when tested 3 months later with a lethal inoculum of stabilate, except 2 cattle in the 10-3 dilution group. As a result of a theileriosis problem at about day 60 after inoculation in 2 cattle given 10-2 dilution of stabilate and buparvaquone treatment on day 0, an additional 5 cattle were given 10-2 dilution of stabilate and developed a good immunity after buparvaquone treatment. None was shown to develop the carrier state. Treatment with buparvaquone on day 8 after infection with 100 dilution of stabilate was not successful since 2 died. The stabilate used was shown to produce reproducible infection in cattle at different dilutions.
Infection of bovine T cell clones with genotypically distinctTheileria parvaparasites and analysis of their cell surface phenotype
Authors: Conrad P. A. , Baldwin C. L. , Brown W. C. , Sohanpal B. , Dolan T. T. , Goddeeris B. M. , Demartini J. C. , Ole-Moiyoi O. K. 
Published: June 2009

SummaryDifferent stocks and stabilates within a stock ofTheileriaparvawere analysed for genotypic differences and for their effect on the expression of host cell surface antigens following infection of BoT8+T lymphocyte clones. The parasites were characterizedin vitroby hybridization ofT. parva- specific DNA probes to Southern blots of endonuclease-digested DNA from the infected T cell clones. Phenotypic changes in the host lymphoblastoid cells before and after infection were examined using lineage-specific monoclonal antibodies which reacted with the differentiation antigens BoT2, BoT4, Bo6, BoT8 and a null cell marker on bovine T cells. Expression of Class I and Class II major histocompatibility complex (MHC) antigens on the cell populations was also assessed. Results of this study indicate that genotypically different parasites exist among and withinT. parvastabilates and that the expression of Bo6, BoT8 and the null cell marker was differentially altered by infection with parasites from different stocks or from different stabilates of the same stock. Expression of Class II antigens was significantly increased after infection. Moreover, clones that were derived from the same cell line but had genotypically distinctT. parvaparasites, also showed differences in expression of Bo6 and BoT8 and the null cell marker.
Mesocestoides corti: parameters of infection in CBA/Ca mice and the effect of introducing a concomitant trematode infection
Authors: Chernin J. , McLaren Diane J. , Morinan A. , Jamieson B. N. 
Published: June 2009

SummaryCBA/Ca mice infected with the tetrathyridia of Mesocestoides corti were exposed to Schistosoma mansoni cercariae either simultaneously, or at varying intervals after the initial M. corti infection. Cohorts were infected with either parasite alone. The dual infected mice and the mice harbouring M. corti alone were significantly heavier than either naive controls or mice carrying the S. mansoni infection only. The livers and spleens from dual infection mice were also found to be significantly heavier than those from other groups. Free M. corti tetrathyridia were reduced in number in the peritoneal cavity of dual infected mice, as compared with mice harbouring a single infection. Furthermore, the intensity of the initial M. corti infection, as measured by the number of capsules surrounding parasites in the liver, was reduced when the mice experienced an S. mansoni infection 21 days later. The mice which were exposed to M. corti only exhibited more mast cells and eosinophils around encapsulated tetrathyridia in the liver than did dual infection mice, while cells surrounding S. mansoni egg granulomas in the liver were significantly increased in dual infection mice. An increase in serum alkaline phosphatase levels was detected in both the mice receiving the dual infection and the mice with the S. mansoni only infection, but not in mice harbouring M. corti alone.
The influence of individual, social group and household factors on the distribution of Ascaris lumbricoides within a community and implications for control strategies
Authors: Haswell-Elkins Melissa , Elkins D. , Anderson R. M. 
Published: June 2009

SummaryThe distribution of Ascaris lumbricoides within a community was examined at an initial mass anthelmintic treatment programme (January 1984) and following an 11-month period of reinfection (November 1984). Similar patterns of the negative binomial parameter k (an inverse measure of parasite aggregation) and the proportion of parasites within the most heavily infected quartile of the community were recorded at the two dates. The pattern of parasite aggregation within individuals, measured by parameter k, appears to be a stable characteristic of this host-parasite relationship. Significant variation in the intensity of infection was observed between households in the community. The number of family members living in the house strongly influenced the mean Ascaris burden and proportion of relatively heavy infections within adults and children. This finding suggests that the density of people in a house positively influences the frequency of exposure to infective stages of Ascaris, which in turn plays a major role in determining which individuals will harbour heavy infections. Positive correlations were recorded between the initial and reinfection burdens of individuals, relative to others in the community. The correlations were strongest in the youngest and oldest age groups and were more frequently significant among age-stratified groups of females, compared to males. A comparative examination of hypothetical treatment strategies suggests that for Ascaris infections in this community, targetting age groups with anthelmintic treatment would probably be more cost-effective in the long term in reducing the abundance of this parasite than selective treatment of individually identified heavy infections.