bluuebunny/crossref_metadata_2025_split huggingface dataset:
A freeze fracture study of the developing tegumental outer membrane ofSchistosoma mansoni
Authors: McLaren Diane J. , Hockley D. J. , Goldring O. L. , Hammond B. J. 
Published: June 2009

SummaryThe freeze fracture technique has been used to quantify changes in the integral components of the double outer membrane ofSchistosoma mansoniduring the 6-week period of development within the mouse. The intramembraneous particle (IMP) density on the P1face begins to rise Within 6 h of host penetration, reaches a maximum at day 4 and then falls rapidly after day 9, so that it is at a low level between 3 and 6 weeks. The E1 face IMP density follows the same course as that of the P1 face except that maximum particle density is recorded on day 1 and the counts begin to fall on day 5. The IMP density on the P1face remains at a consistently low level throughout development. The E2face IMP density rises gradually to a peak at day 4, when the parasites have migrated to the lungs, and remains thereafter at a similar level, so that by 6 weeks the E2face has a higher IMP density than the other three fracture faces. The E2face IMP show a marked increase in size on day 4. Morphological studies indicate that a different type of inclusion body makes a transient appearance in the tegument of the lung worms, and immunocytochemical techniques show the lung worms to be nonimmunogenic. It is suggested, therefore, that the E2face IMP may represent complexes of parasite antigens and acquired host antigens. The tegumental membranes of cultured specimens have also been examined by freeze fracturing and the IMP densities compared with those obtained fromin vivoparasites; the cultured schistosomula have a lower E2face particle density than thein vivospecimens.
The activity of methyl benzoquate and clopidol against Eimeria maxima: synergy and drug resistance
Authors: Joyner L. P. , Norton C. C. 
Published: June 2009

SummarySynergy between clopidol and methyl benzoquate against Eimeria maxima was shown to be supra-additive. Collateral sensitivity to these drugs could not be demonstrated in resistant lines of this parasite. Resistance to methyl benzoquate and clopidol was not transferred when lines of E. maxima, resistant to the respective drugs, were propagated together. The failure to demonstrate this phenomenon was judged not to be due to synergy between the drugs. Attempts to induce simultaneous resistance to both drugs failed, although resistance to methyl benzoquate was readily acquired by a line of E. maxima resistant to clopidol. Induced resistance to clopidol in a methyl benzoquate-resistant line required numerous passages.
Population biology of Paragonimus kellicotti metacercariae in central Ohio
Authors: Stromberg P. C. , Toussant M. J. , Dubey J. P. 
Published: June 2009

SummaryThe distribution of Paragonimus kellicotti metacercariae in a mixed population of crayfish from a small central Ohio stream was studied for two seasons. The distribution of worms in crayfish approximates the negative binomial distribution. Prevalence and intensity of infection increased with crayfish body weight. Although no difference in intensity of infection was noted between male and female crayfish, the prevalence of infection was higher in males. The data demonstrate a seasonal recruitment of metacercariae into the crayfish only during late summer and autumn. Metacercariae can live for over 1 year but some die and become mineralized. There is no apparent detrimental effect of P. kellicotti infection on the crayfish. The seasonal timing of life-cycle events is postulated.
Host–parasite relationships of Zygocotyle lunata (Trematoda) in the domestic chick
Authors: Fried B. , Nelson P. D. 
Published: June 2009

SummaryDomestic chicks were infected with Zygocotyle lunata to determine gross and histopathological effects on the caecal tissues, to observe the method of feeding by worms and to examine the effects of crowding on the growth and development of the worm. Caecal weights and dimensions were significantly reduced in infected chicks. Caecal debris, abundant in control chicks, stained positive for proteins, polysaccharides, acid mucopolysaccharides and neutral fats. Caecal debris was rarely seen in infected chicks. The lumen of the intestinal caeca of the worms contained acellular material which showed protease activity and stained positive for proteins, polysaccharides and acid mucopolysaccharides. Histopathological effects of the infection showed a disruption of the architecture of host caecal mucosa, worm to worm attachment, tissue plugs in the worm acetabulum, and an engorgement of host mucosal tissue with erythrocytes. Stunting due to worm crowding was very evident and by 2 weeks post-infection, worms from single-worm infections were sexually mature and more than twice the length of immature flukes obtained from chicks infected with 100–500 cysts.
Differences in the chemical composition and carbohydrate metabolism of Echinococcus granulosus (horse and sheep strains) and E. multilocularis
Authors: McManus D. P. , Smyth J. D. 
Published: June 2009

SummaryMetabolic studies in vitro and studies on chemical composition indicate basic biochemical differences between the horse and sheep strains of Echinococcus granulosus and between these and the closely related species, E. multilocularis. The horse strain of E. granulosus has a similar level of DNA, but significantly more polysaccharides and lipids, with less RNA and protein than the sheep strain. E. multilocularis has significantly more lipids and DNA but less polysaccharides than the horse and sheep strains of E. granulosus, more RNA and protein than the horse strain but similar protein to and less RNA than the sheep strain. Incubations under air and under 95% N2-5% CO2 for 3 h show that only E. multilocularis takes up glucose, that all three forms consume different amounts of oxygen and endogenous glycogen and produce different concentrations of lactate, succinate, acetate, malate, pyruvate, propionate and ethanol as end products of carbohydrate metabolism.
The inheritance of thiabendazole resistance in Haemonchus contortus
Authors: Le Jambre L. F. , Royal W. M. , Martin P. J. 
Published: June 2009

SUMMARYHaemonchus contortus worm populations isolated from naturally infected sheep at the Pastoral Research Laboratory, Armidale, N.S.W., were found to contain approximately 20% of worms resistant to a 50 mg/kg dose of thiabendazole. Following 3 generations of selection with 50 mg/kg thiabendazole the number of worms removed by the anthelmintic was too small to detect differences between treated and control groups. After more than 15 generations of selection, matings between males from the selected strain and non-resistant females produced resistant males and females in equal numbers. Thus, thiabendazole resistance does not appear to be sex-linked. A dose–response assay on the F2 adults indicated that worms from female resistant × male non-resistant crosses were more resistant than F2 adults of the reciprocal cross. An in vitro technique that identified thiabendazole-resistant eggs by their ability to hatch in a solution containing thiabendazole and 0·1% NaCl solution was also used to study the inheritance of resistance. F1 eggs had similar LC50's to the resistant parents. F2 and back-cross eggs from an original mating of thiabendazole-resistant females × non-resistant males had a higher LC50 than F2 and back-cross eggs from the reciprocal mating, indicating a degree of matroclinous inheritance of resistance. However, the resistant parents had tolerances to thiabendazole exceeding those of F2. F3 eggs had a resistance distribution that ranged from that of the resistant to the non-resistant parent. No significant deviation from linearity was observed in any of the dose–response lines. These results indicate that thiabendazole resistance in H. contortus worms is inherited as an autosomal and semi-dominant trait.
Morphological and histochemical observations on oocyte atresia in Centrorhynchus corvi (Acanthocephala)
Authors: Parshad V. R. , Guraya S. S. 
Published: June 2009

SummaryA morphological and histochemical study has been made of atresia in oocytes in the ovarian balls of an acanthocephalan (Centrorhynchus corvi). Growing oocytes and mature oocytes have been observed to undergo atresia. With the start of atresia, the nuclear and cytoplasmic components are observed to be greatly altered. The atretic oocytes develop abnormal aggregations of cell components, which contain proteins, phospholipids and lipoproteins. It is suggested that the cellular products of degenerating oocytes are gradually absorbed by the supporting syncytium. The atresia of growing oocytes is greater in uninseminated than in inseminated females, which indicates that in the absence of a mating stimulus atresia occurs more frequently.
Genetic resistance to helminths. The influence of breed and haemoglobin type on the response of sheep to re-infection with Haemonchus contortus
Authors: Altaif K. I. , Dargie J. D. 
Published: June 2009

SummaryThe influence of genetic factors on acquired resistance to Haemonchus contortus infections in sheep was investigated. Animals whose primary infections were terminated with an anthelmintic failed to develop any immunity against subsequent challenge as judged by worm numbers. Nevertheless, all were better able to retard the development and reduce the fecundity and haematophagic activities of their parasite populations than animals undergoing primary infections. High levels of resistance, as judged by all these parameters, were observed in most animals when the challenge larvae were superimposed on existing worm populations. The patterns of worm establishment and disease indicated that genetic factors operated in determining resistance, since fewer worms became established and less severe clinical and pathophysiological changes were observed in Scottish Blackface than in Finn Dorset sheep with the same haemoglobin type. Similar advantages were displayed by animals with haemoglobin AA and to a lesser extent those with haemoglobin AB over haemoglobin BB types. The importance of breed was further indicated by the occurrence of ‘self-cure’ in the majority of the Scottish Blackfaces but in only one Finn Dorset. There was no evidence that this reaction was associated with haemoglobin type.
Eimeria maxima: a comparison of two laboratory strains with a fresh isolate
Authors: Norton C. C. , Hein Helen E. 
Published: June 2009

SummaryOocysts of the Weybridge and Houghton strains ofEimeria maximaand a fresh field isolate were similar and measured on average 30·9 × 22·4 μm. The Weybridge strain and the field isolate produced similar pathogenic effects in 6-week-old chickens, high doses causing 50–80% mortality and severe weight loss. The Houghton strain was slightly less pathogenic and few birds died but more oocysts were produced. With each strain, a single dose gave complete immunity to a light challenge with the homologous strain. Two or 3 immunizing doses gave complete immunity to a heavy homologous challenge but were not sufficient to protect against heterologous challenge.
Periodicity in the hatching of digenean eggs: a possible circadian rhythm in the life-cycle ofTransversotrema patialense
Authors: Bundy D. A. P. 
Published: June 2009

SUMMARYThe temporal distribution of hatching of the embryonated eggs ofTransversotrema patialensehas been examined under different temperature and illumination regimens. Under a DL 12: 12 regimen at 30°C egg hatching exhibited a circadian rhythm with a period of 24 h. Within a diel time-frame hatching was distributed over the final 9 h of the light period with less than 2% of the eggs hatching during the dark period. This pattern was temperature independent over the range 25 to 30°C and persisted under constant illumination. It is suggested that the timing of hatching is under endogenous control and is functionally related to a circadian rhythm of behaviour of the intermediate host mollusc,Melanoides tuberculata.
Observations on the development of the ovarian balls ofMoniliformis(Acanthocephala)
Authors: Asaolu S. O. , Whitfield P. J. , Crompton D. W. T. , Maxwell Lesley 
Published: June 2009

SUMMARYObservations have been made on the ultrastructure of objects identified as ovarian balls from femaleMoniliformisafter 1, 3, 5, 7 and 9 days in the rat. Similar objects are present in the body cavity of female cystacanths from cockroaches. The ovarian balls from 1-day-old worms are formed of several cells which are enclosed within a surface coat. During development, the ovarian balls increase in size and cell number and the internal organization appears to become more complex. After 9 days of development in the rat, the surface coat of the ovarian balls can no longer be observed and microvilli are present. It also appears that the supporting syncytium has been formed by this time.
Association between Pelodera strongyloides (Nematoda: Rhabditidae) and wood mice, Apodemus sylvaticus
Authors: Hominick W. M. , Aston Amanda J. 
Published: June 2009

SUMMARYPelodera strongyloides larvae were found in the conjunctival sacs of Apodemus sylvaticus and Clethrionomys glareolus and in hair follicles of A. sylvaticus. Those in the eyes were 3rd-stage larvae while most of those in the dermis were early 4th stages. There was no evidence of pathology and sections of the skin showed that the nematodes were well-tolerated by the mice. Nematodes emerged from the skin of freshly killed mice and moulted once to the adult stage in 1–2 days at 15 °C. The stimulus to resume development appeared to be a reduction in temperature rather than presence of bacterial food or reduction in osmotic pressure. Countless generations ensued on nutrient agar provided the nematodes were periodically sub-cultured onto fresh agar. Nematodes from the eyes died in culture. Dauerlarvae of P. strongyloides were produced in exhausted cultures. They resumed development on fresh agar but not in distilled water. About half could be induced to exsheath by a temperature similar to that of mouse skin. A. sylvaticus probably accumulates nematode larvae in the dermis during its life and the nematodes resume development when the host dies.
Taenia saginata (Cestoda) in western Kenya: the reliability of faecal examinations in diagnosis
Authors: Hall Andrew , Latham M. C. , Crompton D. W. T. , Stephenson L. S. 
Published: June 2009

SUMMARYThe prevalence of Taenia saginata (Cestoda) among 146 predominantly Pokot tribesmen in western Kenya was studied in an attempt to assess the reliability of detecting infections by faecal examinations. Firstly, a single faecal sample was microscopically examined after being processed by a standard ether sedimentation technique. Secondly, all subjects were treated with niclosamide and a purgative and the tapeworms were recovered. In this way the efficiency of diagnosing infections by faecal examinations was estimated. T. saginata eggs were found in the faeces of 68% of the men who were eventually found to be infected. Information was collected by interview from all subjects about whether they were or ever had been infected with tapeworms and about the form of treatment previously sought or taken. Eleven out of 25 men were apparently unaware of their tapeworm infections while no evidence of infection was found among 10 of the 24 reportedly infected men. A change in the pattern of treatment for tapeworms was reported which may have resulted in a recent decline in the prevalence of infection.
New defined and semi-defined media for cultivation of the flagellate Trichomonas vaginalis
Authors: Linstead David 
Published: June 2009

SUMMARYStudies on the nutrition and physiology of Trichomonas vaginalis have been hampered by the lack of a defined synthetic medium in which to grow the organism. New synthetic media free of ill-defined supplements and serum which support good growth of T. vaginalis have been developed in this study. The first successful approach to a defined medium resulted from the modification of the tissue-culture medium CMRL 1066. Essential modifications included (1) lowering the redox potential of the medium by adding high levels of ascorbate and (2) modifying the buffer system. Subsequently, CMRL 1066 was replaced by two new media DL7 and DL8 which have greater flexibility in their formulation and permit improved serum-free growth. Serum was replaced by bovine serum albumin and cholesterol, together with either a glyceryl fatty acid ester or a defined mixture of fatty acids. Preliminary nutritional studies using the new media have indicated a requirement for saturated and unsaturated fatty acids and a sterol.
The effect of concurrent infection with Trichinella spiralis on Hymenolepis microstoma in mice
Authors: Howard R. J. , Christie P. R. , Wakelin D. , Wilson M. M. , Behnke J. M. 
Published: June 2009

SummaryThe intestinal changes brought about by rejection of Trichinella spiralis from mice were studied in relation to their effects on a concurrent infection with Hymenolepis microstoma, a cestode not normally rejected from mice. The rejection phase of T. spiralis was associated with a marked stunting of growth of H. microstoma given just before, during, or just after rejection of the nematode. The survival of H. microstoma was affected only when rejection of T. spiralis coincided with the intestinal phase of the cestode: if T. spiralis rejection was timed to occur after the scolex of the cestode had entered the bile duct there was no loss of H. microstoma. It is suggested that the adverse effects on growth and establishment of H. microstoma were due to the non-specific inflammatory component of the host's response to infection with T. spiralis.
An ultrastructural study on the role of Kupffer cells in the process of infection by Plasmodium berghei sporozoites in rats
Authors: Meis J. F. G. M. , Verhave J. P. , Jap P. H. K. , Meuwissen J. H. E. Th. 
Published: June 2009

SUMMARYThe interactions in vivo between Plasmodium berghei sporozoites and Kupffer cells in rat livers were studied by transmission electron microscopy. By 10 and 15 min after inoculation, sporozoites were both free in the liver sinusoids and inside endocytotic vacuoles of the Kupffer cells. The latter cells were very active in phagocytosing sporozoites, bacteria and red blood cells. The sporozoites retained their integrity inside the endocytotic vacuoles and no signs of lysosomal digestion were observed. Sporozoites seen within endocytotic vacuoles 1 h after inoculation were still morphologically intact, although bristle-coated vesicles fused with the vacuole membrane. Evidence is presented which suggests that Kupffer cells transport sporozoites towards the space of Disse and adjacent hepatocytes. No sporozoites were seen to penetrate an endothelial cell or its narrow fenestrae. It is proposed that Kupffer cell passage, rather than gaps in the sinusoidal lining, represents the normal route that sporozoites take to circumvent the endothelial barrier. The localization of exo-erythrocytic forms was made easier by the use of Brown Norway rats in which many more parasites develop than in the Wistar rats. The distribution pattern of the parasites was found to be mainly around the ‘periportal’ zones of the acini of liver tissue.
Infection of mammalian cells with Theileria species
Authors: Stagg D. A. , Young A. S. , Leitch B. L. , Grootenhuis J. G. , Dolan T. T. 
Published: June 2009

SUMMARYExperiments were carried out to determine the susceptibility of mammalian cells to infection with different species of Theileria in vitro. Sporozoites of Theileria parva (parva), Theileria parva (lawrencei) and Theileria taurotragi were isolated from Rhipicephalus appendiculatus ticks by grinding infected ticks in medium, filtering the suspension and concentrating by centrifugation. The sporozoites were used in attempts to infect in vitro peripheral blood leucocytes harvested from 16 different mammalian species which included 12 species of Bovidae from 6 different sub-families. The technique was shown to be both sensitive and reproducible. The sporozoites of T. parva (parva) infected and transformed cells from 2 species of the sub-family Bovinae, the two cattle types and African buffalo. Theileria parva (lawrencei) infected and transformed cells from the two cattle types, African buffalo and Defassa waterbuck. Theileria taurotragi sporozoites infected in vitro cells from 11 different species of Bovidae which were members of 6 sub-families; Bovinae, Tragelaphinae, Reduncinae, Alcelaphinae, Antilopinae and Caprinae. Transformed lymphoblastoid cell lines were established from 7 of the species infected. Sporozoite attachment and infection was not observed with non-susceptible bovid host cells, nor were any of the non-bovid leucocytes infected by the parasites. The host range observed in this study corresponded to the known host range in vivo.
Kinetics of proglottid formation, maturation and shedding during development of Hymenolepis nana
Authors: Kumazawa H. , Suzuki N. 
Published: June 2009

SUMMARYGrowth of Hymenolepis nana in mice is analysed by identifying designated stages of proglottid maturation in the strobila, and by determining the numbers of proglottids between them and the posterior terminus of the worm, as a function of time after cysticercoid infection. The proglottid maturation rate was fairly constant between stage A (onset of the somatic primordium formation) and stage B (first appearance of sperms in the seminal vesicle), but gradually fell after stage B, during pre-patent development of the worm. The actual rate of proglottization during this period coincided well with that estimated from the number of proglottids between stages A and B on an assumption of a certain maturation rate. This procedure is extended to estimate the rates of proglottid formation and shedding during later development. It is deduced that the absolute rate of proglottization increases until day 12, gradually decreasing afterwards, and that from 2300 to 2800 proglottids are shed by day 20, until which from 4000 to 4500 proglottids have passed stage A. It is shown that the proportionate increase of the gravid region in older worms depends not only on a decrease in the rate of proglottization, but also on the prolonged period during which proglottids stay in the strobila.
Eimeria mitis in mixed infections with E. acervulina and E. brunetti in the fowl
Authors: Joyner L. P. , Norton C. C. 
Published: June 2009

SUMMARYEimeria mitis and E. acervulina affect different areas of the intestine. Young chicks received E. mitis with or without E. acervulina in doses ranging from 2 to 128 × 104 oocysts. Mixed infections produced significantly more severe effects on growth than single infections of either species. The ratio of villus height to total mucosal thickness was reduced throughout the intestine in birds which received the mixed infection. E. mitis and E. brunetti affect the same area of the intestine. Single infections of E. brunetti in a range of doses from 1.25 to 20 × 103 oocysts produced a similar reduction in growth. When 20 × 103 oocysts of E. mitis were inoculated simultaneously, the effect on growth was not so severe and the oocyst output of both species was reduced. E. brunetti, superimposed 1, 2 or 3 days after an E. mitis infection, produced no greater effect on growth than E. mitis alone. Similarly, infections of E. mitis, superimposed on E. brunetti had no greater effect on growth than the latter species alone. Oocyst output of E. brunetti in superimposed infections was not reduced but peak output was delayed.