bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasmodium bergheiandPlasmodium chabaudi chabaudi: development of simplein vitroerythrocyte invasion assays
Authors: McNally J. , O'donovan S. M. , Dalton J. P. 
Published: June 2009

SUMMARYErythrocyte invasion assays are described for two species of rodent malaria, namelyPlasmodium bergheiandP. c. chabaudi. These invasion assays are simple, are carried out using a candle jar and allow a number of assays to be performed simultaneously. Our results demonstrate that both rodent malaria species show anin vitropreference for reticulocytes although the preference ofP. c. chabaudifor these cells is not as marked as that ofP. berghei. The details of our invasion assays and our results obtained are discussed.
Impairment of growth of Leishmania donovani by Trypanosoma brucei during co-culture
Authors: Coppens I. , Ter Kuile B. H. , Opperdoes F. R. 
Published: June 2009

SUMMARYCells of Leishmania donovani in co-culture with Trypanosoma brucei, were severely affected in their growth, resulting in swelling and subsequent lysis. Similar effects were also observed when Crithidia luciliae or Phytomonas sp. were co-cultured with T. brucei. Direct contact between the cells under investigation and T. brucei was necessary because T. brucei did not hamper the growth of the other trypanosomatids, when separated by a filter with 0.2 μm pore size. Examination of this phenomenon at the ultrastructural level, in a co-culture of L. donovani and T. brucei, suggests that the plasma membrane permeability is increased in the former, as a result of a close cellular contact between the two cell types.
Theileria annulata-infected cells produce abundant proteases whose activity is reduced by long-term cell culture
Authors: Baylis H. A. , Megson A. , Brown C. G. D. , Wilkie G. F. , Hall R. 
Published: June 2009

SUMMARYLysates ofTheileria annulata-infected bovine lymphoblastoid cells and their uninfected counterparts were tested for protease activity using gelatin substrate SDS–PAGE. The infected cells produced a number of extra activities at pH 8·0 in the presence of Ca2+. Calcium was found to enhance the activites but was not an absolute requirement. Studies using inhibitors, including E64, 3,4-dichloroisocoumarin, pepstatin and 1, 10-phenanthroline suggested that the activities were metalloproteases. We analysed two vaccine lines; the Ode line from India and the Ankara Pendik line from Turkey. In the Ode line the later passage had very much reduced levels of the enzyme activities. In the case of the Ankara Pendik line both stages analysed had very low protease activities, but a reduction from the early to late passage was also observed. The reduction in the level of protease activity was also observed as a gradual process during on-going culture of lines derived from the Hissar and Ode stocks. In the Ode line we demonstrated a parallel decrease in the production of microschizonts upon temperature shiftin vitro.
Ultrastructural studies on the miracidium ofSanguinicola inermis(Digenea: Sanguinicolidae)
Authors: McMichael-Phillips D. F. , Lewis J. W. , Thorndyke M. C. 
Published: June 2009

SUMMARYThe miracidium ofSanguinicola inermiscontains a stylet and rodlet complex located within the single apical gland, which lies between a pair of lateral glands. The miracidial stylet consists of an arrangement of hollow tubes, composed of microtubules, connected at their base to large secretory granules and opening anteriorly through the apical papilla. A single rodlet lies adjacent to the stylet base and at least 8 rodlets are arranged at the apical tip of the stylet. The surface plasma membrane of the apical papilla is drawn into knob-like projections and 2 ciliated sensory endings are associated with the papilla. The ultrastructure of the apical gland, especially the stylet and rodlet complex, is related to the requirement for sanguinicolid miracidia to penetrate the double barrier of fish and snail hosts.
Analysis of two-dimensional protein patterns from developmental stages of the potato cyst-nematode,Globodera rostochiensis
Authors: De Boer J. M. , Overmars H. A. , Bakker J. , Gommers F. J. 
Published: June 2009

SUMMARYTwo-dimensional polyacrylamide gel electrophoresis was used to examine the differences in total protein composition between two motile stages and two sedentary stages of the potato cyst-nematode,Globodera rostochiensis. Using a sensitive silver stain, 542 reproducible protein spots were distinguished. A list of these spots is presented, showing their apparent molecular weights, estimated isoelectric points, and occurrences in the different developmental stages. When the protein patterns were compared, 401 spots were found to change their presence or size in one or more of the four developmental stages. It is therefore estimated that during the post-embryonic development ofG. rostochiensis, 74% of the polypeptides undergo modulation of their synthesis, or are affected by protein degradation or modification. In the motile stages several abundant proteins were present, which disappeared or decreased in concentration in the sedentary stages. Some of these proteins are presumably muscle proteins, and their modulation may illustrate the degeneration of body-wall musculature in the sedentary stages. It is concluded that the potato cyst-nematode has a very dynamic protein metabolism.
In vitroexcystation ofCryptosporidium parvum
Authors: Robertson L. J. , Campbell A. T. , Smith H. V. 
Published: June 2009

SUMMARYProtocols forin vitroexcystation of oocysts ofCryptosporidium parvum, including different chemical pre-incubation steps, were compared to examine some of the biochemical triggers involved in excystation and to define anin vitroexcystation protocol of a reproducibly high efficiency. Pre-incubation steps which increased the permeability of the oocysts were found to enhance excystation dynamics and pre-treatment of oocysts with saliva was found to decrease the permeability and reduce excystation. Although excystation was maximal after incubation for 4 h, sporozoites tended to lyse over this period, and maximum sporozoite recovery occurred after 30 min. The results obtained are discussed in relation to excystation protocols adopted by different research groups and a number of recommendations are given forin vitroexcystation ofC. parvumoocysts.
Purification of an agglutinin from the haemolymph of the snail Bulinus nasutus and demonstration of related proteins in other Bulinus spp.
Authors: Harris R. A. , Preston T. M. , Southgate V. R. 
Published: June 2009

SUMMARYThe snail Bulinus nasutus 1214 possesses a potent haemagglutinin (end-point titre with human erythrocytes, 2−18) in its cell-free haemolymph which also binds to the miracidia (but not other larvae) of the incompatible parasite Schistosoma margrebowiei. We have purified a protein possessing this haemagglutinating property from the plasma of this snail. The native Mr of this protein was estimated by SDS polyacrylamide gel electrophoresis to be 210 kDa; under denaturing conditions in a 7.5% PAGE gel it ran as a major band of 135 kDa. Proteins of similar Mr were also found in the haemolymph of 16 other Bulinus spp. (the major intermediate hosts of human and veterinary schistosomiasis in Africa) although the plasma of none of these agglutinated human erythrocytes. Nonetheless, Cleveland mapping of the Mr 135 kDa bands from these different Bulinus spp. revealed 4 identical major peptide fragments (30, 28, 19 and 16 kDa) in each, thus demonstrating a similarity in the primary structure of these plasma proteins. Antisera from Balb/C mice immunized with the 135 kDa polypeptide from Bulinus truncatus 1521 cross-reacted in Western blots with the 135 kDa band of other members of the same truncatus/tropicus species complex but not with species from the africanus or forskalii species groups.
Observations on the feeding behaviour of parasitic third-stage hookworm larvae
Authors: Hawdon J. M. , Volk S. W. , Rose R. , Pritchard D. I. , Behnke J. M. , Schad G. A. 
Published: June 2009

SUMMARYThe feeding behaviour of parasitic 3rd-stage larvae (L3) of the hookworms Ancylostoma caninum, A. ceylanicum and Necator americanus was examined. Less than 11% of A. caninum L3 recovered from the small intestines of dogs infected orally were feeding at 4–48 h post-infection (p.i.). and none of the A. ceylanicum L3 recovered from the intestines of orally infected hamsters had resumed feeding. All L4 of both species recovered at 36 and 48 h p.i. had resumed feeding. On the other hand, approximately 16% of the A. ceylanicum L3 recovered from the skin of percutaneously infected hamsters at 18 h were feeding, and the percentage feeding increased to nearly 58% at 44 h p.i. Necator americanus L3 recovered from the skin of percutaneously infected neonatal hamsters resumed feeding at 6–12 h p.i. and reached 90–94% by 18 h. Feeding began to decline at 66 h, and reached 29% at 120 h p.i. This decrease was associated with the migration of larvae from the skin to the lungs. By 192 h p.i. over 95% of the larvae had reached the small intestine, and all had moulted to the L4. The results indicate that parasitic L3 resume feeding in the skin during percutaneous infections, and suggest that feeding by hookworm L3 correlates with the resumption of development.
Stereological estimation of the total number of neurons in the asexually dividing tetrathyridium of Mesocestoides corti
Authors: Yaegashi H. , Howard C.V. , McKerr G. , Burns A. 
Published: June 2009

SUMMARYFifty tetrathyridia of Mesocestoides corti showing various degrees of scolex fission during asexual multiplication were subjected to estimation of the total number of neurons in the central ganglia, using a ‘fractionator’ designed sampling scheme on every 10th Historesin section through the specimen. Neurons were stained with Cresyl fast violet and viewed by transmission light microscopy. Cells were only counted if a nucleolus was present. The animals were divided into groups according to their stage in the asexual reproduction process indicated by head shape and sucker number. Animals which had a narrow head with 4 suckers contained about 250 neurons. As their heads became wider, in preparation for fission, neurons were overproduced by up to 5-fold. As additional suckers were developed (8 in total), neurons were reduced to about 500. Finally, when the animals had 2 clearly discernible heads, with 4 suckers on each, the total number of neurons (per head) was again approximately 250. As the heads became wider again, neuron over-production recommenced. Exceptionally shaped animals with an X- or T-shaped single head were observed. These results suggest that there is a preparatory stage for neuronal regeneration, during which the basic population of neurons is about 250. This is followed by neuron over-production followed by a selective cell death of neurons which occurred during asexual multiplication. Another cycle for neuronal regeneration can occur before an animal completes its fission process.
Role of reactive oxygen species in expulsion ofNippostrongylus brasiliensisfrom rats
Authors: Batra S. , Srivastrava J. K. , Gupta S. , Katiyar J. C. , Srivastava V. M. L. 
Published: June 2009

SUMMARYTo understand the mechanism for the expulsion ofNippostrongylus brasiliensisfrom rats, age-dependent variations in the metabolism of reactive oxygen species in the parasite and the host intestines were examined.N. brasiliensisshowed an age-dependent increase in its susceptibility to xanthine-xanthine oxidase andt−butyl hydroperoxide generated oxidants as well as to H2O2. Protection obtained with several scavengers suggested that the worms were damaged by the combined action of oxidants generated by thein vitrosystems employed. The level of superoxide dismutase in the nematode and its release into the surroundings exhibited a marked depression with advancement of age. No such alteration was, however, recorded for catalase and glutathione peroxidase. An appreciable decrease in the level of reduced glutathione in olderN. brasiliensisappears to render them prone to oxidant attack. The rat intestines, on the other hand, exhibited an appreciable depression in catalase and a reduced glutathione content with progress of the infection. Vitamin E levels were elevated. The release of O27and H2O2by the intestines was also found to be greater during later stages of the infection. The combined effect of the changes observed inN. brasiliensisand in the rat intestines may be at least partly responsible for expulsion of the nematode from the rats after day 10.
Preliminary analysis of the transmission dynamics of Theileria parva in eastern Africa
Authors: Medley G. F. , Perry B. D. , Young A. S. 
Published: June 2009

SUMMARYTwo mathematical models are developed that investigate the transmission dynamics of Theileria parva by the ixodid tickRhipicephalus appendiculatus to cattle in endemically stable areas. A method of estimating the rate of infection to cattle ofT. parva at the endemically stable state is given. Empirical estimates of ail the parameters in the model are available. The degree to which animals that have recovered from theileriosis (the ‘carrier’ state) are able to transmit the infection to tick nymphs or larvae is a crucial determinant of the dynamics of infection in a herd. Two control methods influencing the transmission of infection are considered – infection and treatment immunization and the reduction in tick feeding by acaricide application. The impact of each method on the transmission of infection is evaluated. Future developments and the data required to predict the dynamics of T. parva infections in cattle and ticks are discussed.
An IgG (Fcγ,)-binding protein ofTaenia crassiceps(Cestoda) exhibits sequence homology and antigenic similarity with schistosome paramyosin
Authors: Kalinna B. , McManus D. P. 
Published: June 2009

SUMMARYPrevious studies from this laboratory have suggested the presence of antibody-binding molecules on the surface ofTaenia crassicepsmetacestodes. We now report the purification of aT. crassicepsFcγ-binding protein which has an equivalent molecular size (96 kDa), is antigenically similar and exhibits significant amino acid sequence homology to schistosome paramyosin. The similarities in molecular weight of theT. crassicepsprotein,Schistosoma mansoniparamyosin and antigen B ofT. solium, the close amino acid sequence homologies between theT. crassicepsprotein andS. mansoniparamyosin and betweenS. mansoniparamyosin and antigen B ofT. solium, and the antigenic similarity of theT. crassicepsprotein with paramyosin indicates that this family of platyhelminth proteins are closely related. The known characteristics ofT. soliumantigen B (collagen binding affinity; disruption of complement function) and the Fcγ-binding activity of theT. crassicepsmolecule suggests that this class of proteins may be multifunctional, fulfilling not only a structural role but also as components interacting with the host immune system to increase parasite survival.
Hookworm infections and human iron metabolism
Authors: Crompton D. W. T. , Whitehead R. R. 
Published: June 2009

SUMMARYAncylostoma duodenale and Necator americanus are extremely common species of soil-transmitted helminth which flourish where poverty and malnutrition prevail. Hookworms contribute significantly to iron-deficiency anaemia, which remains one of the world's major nutritional problems, through the feeding activities of intestinal stages leading to chronic blood loss into the gut. In this article, a mathematical model is proposed to explain how human iron metabolism may respond to hookworm infection of varying intensity. The model draws attention to the importance of the regulation of stored iron levels in the process. The results from the model are presented for the effects of hookworm infection on the iron metabolism of a healthy adult male. Calculations are also presented in which the effects of hookworms on the iron metabolism of a non-pregnant woman are compared with those of a pregnant woman. Use of the model may help develop a better understanding of the pathology of hookworm disease.
Infection, nutrition and cognitive performance in children
Authors: Connolly K. J. , Kvalsvig J. D. 
Published: June 2009

SUMMARYThe paper considers briefly the nature of cognition and its relationship to intelligence. The information processing model of human cognition is outlined and IQ and DQ are explained. The literature dealing with the effects of malnutrition and parasitic infection on cognitive performance and development in children is selectively reviewed. A speculative hypothesis concerning the psychological effects of parasitic infection is sketched and brief consideration is given to models and measures in research on development.
Models of intermediate complexity in insect-pathogen interactions: population dynamics of the microsporidian pathogen,Nosema pyrausta, of the European corn borer,Ostrinia nubilalis
Authors: Briggs C. J. , Godfray H. C. J. 
Published: June 2009

SUMMARYNosema pyraustais an important microsporidian pathogen of the European corn-borer,Ostrinia nubilalis(Pyralidae), a major pest of corn (maize). The population dynamics of the interaction between the moth and its pathogen have been studied previously using simple models phrased as coupled differential equations, and using large simulation models containing over 150000 coupled equations. A middle approach is adopted here and the interaction studied using an age-structured model written as a system of delay-differential equations. Although the model contains twenty four parameters, estimates for twenty of these were available in the literature. Our model provides a good qualitative match to observed within and between season dynamics and suggests which aspects of the interaction are most important in determining the nature of the system's population dynamics. More generally, we argue that in the absence of better data on insect-disease interactions in natural habitats, valuable insights can be gained by studying equivalent systems in agro-ecosystems. We also argue that models of intermediate complexity that incorporate considerable detail about the natural history of individual interactions, but which are derived from the classical models of animal ecology and epidemiology, offer the most profitable way of modelling insect-pathogen interactions in the wild.
Serotonin and its requirement for maintenance of contractility in muscle fibres isolated fromSchistosoma mansoni
Authors: Day T. A. , Bennett J. L. , Pax R. A. 
Published: June 2009

SUMMARYMuscle fibres isolated from adultSchistosoma mansonicontracted in a dose-dependent manner when exposed to elevated K+with a maximum response obtained with 25 mM K+. These contractions were dependent on extracellular Ca2+since Co2+(5 mM) or nicardipine (1 μM) blocked the high K+contractions. Serotonin (300 nM or higher) was required for maintenance of high K+contractions. With concentrations of serotonin less than 300 nM the response was dose dependent. 5-Methoxytryptamine or α-methylserotonin at 1 μM as well as 10 μM tryptamine were able to substitute for serotonin, but 1 μM 5-carboxyamidotryptamine was ineffective. The order of potency for antagonists (10 μM) was: methiothepin > metergoline > Ly-278,584 = ketanserin. This pattern of responsiveness does not fit well with any known mammalian serotonin receptor subtype. Since forskolin, an adenylate cyclase activator, is able to mimic the action of serotonin and H89, a protein kinase inhibitor, is able to block the effect of serotonin, the effect of serotonin on contractility of the muscle may beviaa cAMP-dependent pathway.
Characterization of three neutral proteases ofSpirometra mansoniplerocercoid
Authors: Kong Y. , Chung Y.-B. , Cho S.-Y. , Choi S.-H. , Kang S.-Y. 
Published: June 2009

SUMMARYIn the pathogenesis of sparganosis, proteases have been considered to play important roles in tissue migration and parasite feeding. Several bands of proteolysis were observed when crude extracts ofSpirometra mansoniplerocercoid (sparganum) were examined using gelatin substrate gel at neutral pH, of which two proteases of 198 and 104 kDa were purified by two chromatographic steps, and a 36 kDa protease was purified by gelatin-affinity and DEAE–anion exchange chromatography. All the purified proteases exhibited optimal activity at pH 7·5 and 0·1 M Tris–HCI. Proteolytic activities at 198 and 104 kDa were inhibited specifically by serine protease inhibitors, and 4-(amidinophenyl)methansulfonyl fluoride (APMSF, 0·5 m) andN-α–p–tosyl-L-lysine chloromethyl ketone (TLCK, 1 mM), which strongly suggested that these two proteases were trypsin-like proteases. The activity of the 36 kDa protease was inhibited byN-tosyl-l-phenylalanine chloromethyl ketone (TPCK, I mM) and chymostatin (0·1 mM), and was potentiated in 10 mM Ca2+which showed that the protease had a chymotrypsin-like property. All the proteases were Schiff(PAS) positive. Proteases of 198 and 104 kDa degraded collagen completely within 24 h. The 36 kDa enzyme cleaved human recombinant interferon-γ (rIFNγ) and bovine myelin basic protein. In addition, all the purified proteins elicited strong antibody responses in the infected patients.
Tsetse–trypanosomiasis challenge to village N'Dama cattle in The Gambia: field assessments of spatial and temporal patterns of tsetse–cattle contact and the risk of trypanosomiasis infection
Authors: Wacher T. J. , Milligan P. J. M. , Rawlings P. , Snow W. F. 
Published: June 2009

SUMMARYThe severity of the trypanosomiasis problem in a particular location is traditionally assessed in terms of a challenge index – the product of some measure of tsetse abundance and infection rate – which is assumed to be proportional to the force of infection. However, this index masks variation in the force of infection between herds and among individuals within herds. It is also not comparable between sites since the relative abundance of tsetse to hosts may vary. We have studied spatial distribution of herds of cattle in relation to tsetse in The Gambia and calculated an index of challenge based on the ratio of vectors to hosts over the livestock ranging area. This index is strongly correlated with estimates of the force of infection calculated from the incidence of infection in susceptible zebu; and it provides information on heterogeneity in exposure of different herds to tsetse.