bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neuromuscular physiology of Hymenolepis diminuta and H. microstoma (Cestoda)
Authors: Thompson C. S. , Mettrick D. F. 
Published: June 2009

SUMMARYThe physiology of the neuromuscular systems in Hymenolepis diminuta and H. microstoma was studied in vitro using intact, adult worm and strips of worm body wall. Intact worms were insensitive to ionic changes in the in vitro buffering system. However, strips of body wall containing longitudinal muscles were extremely sensitive to ionic manipulation. In intact worms tension generated in the strobila had two components; small brief tension peaks up to 500 mg amplitude are superimposed on larger, longer peaks of up to 1200 mg amplitude. Removal of the scolex and neck region either failed to show significant changes in tension, or showed a reduction in amplitude but not of frequency. Muscle contraction of both H. diminuta and H. microsoma were qualitatively similar. In split-worm preparations the concentration of Ca2+ in the bathing solution significantly affected both spontaneous and evoked contractions in H. diminuta and H. microstoma; the addition of CaCl2 greatly reduced the amplitude and frequency of the contractions. The chloride salts of cobalt, barium, cadmium and manganese elicited prolonged contractions of the longitudinal musculature of both H. diminuta and H. microstoma. While CoCl2 was the most effective in stimulating muscle contraction, the magnitude of the response varied with the concentration of Ca2+ in the bath. The results indicate that peripheral inhibition is extremely important in cestode motor control and that extracellular calcium ions may regulate the peripheral inhibitory mechanisms.
The effect of temperature on the behaviour of the infective larvae of Trichostrongylus colubriformis
Authors: Wharton D. A. 
Published: June 2009

SUMMARYThe effect of temperature on the behaviour of the infective larvae of Trichostrongylus colubriformis has been investigated. Larvae acclimatized at 3°C or 20°C respond to sudden or gradual increases in temperature by coiling. Increased temperature may indicate a risk of exposure to desiccation and elicits a behavioural response which optimizes survival. Larvae are straight when inactive; coiling is an active response to specific stimuli. Larval activity is initiated by exogenous stimuli. Mechanical disturbance is a major stimulus, the response being affected by changes in temperature. Larvae acclimatized at 3°C or 20°C show a peak of activity at temperatures between 15 and 25°C.
Swimming behaviour of the cercaria ofTransversotrema patialense
Authors: Bundy D. A. P. 
Published: June 2009

SUMMARYThe spontaneous free-swimming behaviour of the cercaria ofTransversotrema patialensewas recorded using a high-speed micro-cinematographic technique. The sequential change in configuration of the cercaria was analysed quantitatively and the angular relationships of the cercarial components determined with respect to the trajectory of the organism. The cercaria swims tail-first while the tail stem oscillates through an arc of 100–120° with a frequency of 30 Hz at 24°C. The body region oscillates, almost exactly out of phase, through an arc of 180°C at the same frequency. The two furcae execute alternate effective and recovery strokes so that two symmetrical effective strokes are performed during each propulsive cycle. The Reynolds number of the swimming cercaria was approximately 2. The relative importance of viscous and inertial forces in cercarial propulsion is discussed.
The resistance to re-infection of cats repeatedly inoculated with infective larvae of Brugia pahangi
Authors: Denham D. A. , McGreevy P. B. , Suswillo R. R. , Rogers Rosemary 
Published: June 2009

SUMMARYSeven microfilaraemic and five amicrofilaraemic cats which had been repeatedly infected with Brugia pahangi were challenged along with normal cats 28, 14 and 1 day before autopsy. The lymphatics of the amicrofilaraemic cats contained no female adult worms originating from the repeat infections and only two adult males (both from the same cat). Only 5·2 % of the worms in the control cats were recovered from the amicrofilaraemic cats. Most of the challenge worms were killed in the first 24 h. The microfilaraemic cats all contained fertile adult male and female worms derived from the repeated infection but in such low numbers as to indicate considerable resistance to infection. Compared to their controls 26·4% of the challenge worms were recovered. Analysis of the life-cycle stages recovered showed that in both groups there was attrition of all stages and that although a number of worms reached L5 these were all killed later in the amicrofilaraemic cats.
The effect of temperature on the survival and infectivity of the free-living larvae of Nippostrongylus brasiliensis
Authors: Hindsbo O. 
Published: June 2009

SUMMARYThe development, survival and infectivity of larvae of Nippostrongylus brasiliensis at 10 and 21 °C have been studied. In cultures developed for 1 weekat21 °C but stored at either 10 or 21 °C the mean recovery of larvae in 1·5 h Baermann sediment (46% and 42% of total eggs, respectively) and their infectivity (66% and 70% day 8 p.i. recovery, respectively) at 4 weeks of cultivation were similar. However, at 20 weeks of cultivation only a few larvae survived storage at 21 °C (1·4%) and the survivors showed very low infectivity (4·1%), whereas larvae stored at 10 °C retained most of their survival and infectivity rates (41% and 44%, respectively). In cultures developed and stored at 10 °C a lower mean proportion (17%) of the eggs was recovered as larvae at 4 weeks of cultivation. The mean infectivity rate of these larvae increased from 4 to 12 weeks of cultivation (18 % and 42 %, respectively) but was reduced at 20 weeks of cultivation (27 %). An increased proportion of adult female worms was recovered from rats infected with larvae from cultures showing poor development or survival and the fecundity of the adult females decreased in all groups as the storage time of the cultures was increased. Eggs from low fecundity adult worms showed normal development of larvae. The relation between survival, temperature in the habitat and the geographical distribution of the larvae of N. brasiliensis is discussed.
The in vitro cultivation of P. falciparum ookinetes, and their enrichment on Nycodenz® density gradients
Authors: Carter E. H. , Suhrbier A. , Beckers P. J. A. , Sinden R. E. 
Published: June 2009

SUMMARYEmploying a simple method of growing ookinetes of Plasmodium falciparum in culture, 40% of mature gametocytes convert to macrogametes, 4% reach the retort-form ookinete stage and 0·45% become mature ookinetes. A single-step gradient centrifugation method on 12·5% Nycodenz® enriches both gametocytes and ookinetes.
The mode of action of some benzimidazole drugs onTrichinella spiralis
Authors: Fornelio A. Criado , Caabeiro F. Rodriguez , Gonzalez A. Jimenez 
Published: June 2009

SUMMARYIn an attempt to find possible targets for benzimidazole action in muscle-stage larvae ofTrichinella spiralis, the effects of mebendazole and thiabendazole were testedin vivoby oral treatment of infested mice andin vitroby including these anthelmintics in an adequate maintenance medium containing decapsulated larvae. The effects of the anthelmintics on succinate dehydrogenase and fumarate reductase activities, measured in the mitochondrial fraction obtained from thein vivo- orin vitro-treated larvae showed that only thiabendazole causes significant inhibition of fumarate reductase activity. On the other hand, measurements of free glucose, glycogen reserves and soluble protein in the treated larvae indicate thatin vivo, mebendazole and thiabendazole clearly diminish free glucose levels, althoughin vitroonly mebendazole produces the same diminution. Both the glycogen and protein contents of the larvae remained unchanged after treatmentin vivoorin vitro.The importance of these findings with regard to a possible site of action for mebendazole and thiabendazole is discussed.
Physiological and morphological changes associated with recovery from anabiosis in the dauer larva of the nematode Anguina agrostis
Authors: Preston Christine M. , Bird A. F. 
Published: June 2009

SUMMARYMorphological and physiological changes that occur during the rehydration of 2nd-stage infective larvae (L2) of Anguina agrostis are described. The first signs of motility, after 2 days of dehydration, were observed 0·5 h after rehydration and 90 % of the nematodes were moving within 15 h. Anabiotic A. agrostis were able to withstand repeated dehydration and rehydration. These procedures caused A. agrostis to accumulate large lipid droplets, which showed most clearly in the tail region. By means of a double labelling technique, it was shown that cuticle permeability of anabiotic L2 of A. agrostis initially increased slightly during rehydration. This was followed by a sharp decrease in permeability between 1 h and 8 h from the start of the experiment. A slower decline in permeability occurred between 8 h and 16 h and little further decrease occurred between 16 h and 24 h. The results are discussed in relation to the possible involvement of the epicuticle.
Biomphalaria glabrata: changes in calcium reserves following parasitism by larval Schistosoma mansoni
Authors: Shaw M. K. , Erasmus D. A. 
Published: June 2009

SUMMARYLarval Schistosoma mansoni have been shown to induce morphological changes to the internal calcium reserves (in particular the calcareous inclusions in Type A calcium cells and to the inner, nacreous layer of the shell) of Biomphalaria glabrata within 48 h of miracidial penetration. Control experiments have shown that these changes were not due to either the experimental procedures used, mechanical damage or to starvation effects. The effects were, however, analogous to experimentally induced acidosis, suggesting that the rapidly transforming miracidium-sporocyst quickly induces changes in the host's metabolism, presumably by the production and release of CO2 and waste metabolites into the haemolymph.
Transient non-susceptibility toSchistosoma mansoniassociated with atrial amoebocytic accumulations in the snail hostBiomphalaria glabrata
Authors: Richards C. S. , Minchella D. J. 
Published: June 2009

SUMMARYIn someBiomphalaria glabrata–Schistosoma mansonicombinations snails are susceptible to infection as juveniles, but have variable susceptibility as adults. These snails become non-susceptible at the onset of egg-laying and typically revert to susceptibility in old age. Certain stocks ofB. glabratahave the capacity to form amoebocytic accumulations in the atrium, and this ability is under genetic control. The atrial amoebocytic accumulations are transitory, typically appearing at onset of egg-laying and disappearing after a few months. A snail stock which has genetic tendencies for both adult variable susceptibility and atrial amoebocytic accumulations was studied. An association between the time of occurrence of adult non-susceptibility and atrial accumulation is revealed as snails never became infected withS. mansoniwhen amoebocytic accumulations were present. Developing parasites, however, were not necessarily encapsulated and destroyed by amoebocytes. Some sporocysts were able to delay development until the amoebocytic accumulations disappeared. The timing of atrial amoebocytic accumulations and resulting transient non-susceptibility in this host-parasite combination could influence snail population dynamics.
Ascaris lumbricoides infection in pre-school children from Chiriqui Province, Panama
Authors: Holland Celia V. , Crompton D. W. T. , Taren D. L. , Nesheim M. C. , Sanjur Diva , Barbeau Irma , Tucker Katharine 
Published: June 2009

SUMMARYAn epidemiological survey of intestinal parasitic infections was conducted in a sample of 203 children aged 3–5 years from a semi-urban and a rural community in Chiriqui, Panama, in 1983–4. On the basis of stool examinations, the prevalences of Ascaris lumbricoides, Trichuris trichiura, hookworm, Giardia intestinalis, Entamoeba spp. and Strongyloides stercoralis were found to be 27, 34, 14, 15, 5 and 4% respectively. The results from children from the two communities were compared. Polyparasitism occurred significantly more often in rural than semi-urban children. Following anthelmintic treatment with levamisole, the numbers of A. lumbricoides passed/child were recorded and the frequency distribution of the parasite was observed to be highly aggregated with a variance to mean ratio of 10·2. For A. lumbricoides, relationships between worm burden, worm biomass and egg production were investigated. In the data analysis, an attempt was made to explore the influence of numbers of male worms on egg production. The results are compared with those obtained during other recent studies on the epidemiology of A. lumbricoides infection in other countries.
Plasmodium vivax malaria in the common marmoset, Callithrix jacchus: adaptation and host response to infection
Authors: Mitchell G. H. , Johnston D. A. , Naylor B. A. , Knight A. M. , Wedderburn N. 
Published: June 2009

SummaryInfection with Plasmodium vivax was established in splenectomized Callithrix jacchus marmosets by inoculation of parasitized blood from Aotus trivirgatus carrying the Vietnam Palo-Alto line of P. vivax. Subsequent blood passage through intact marmosets resulted in higher peak parasitaemias (about 1% of red cells infected) and the loss of stainable Schüffner's dots in infected cells. Primary infections with the adapted line were patent for 74 days or more, and induced both a substantial antibody response, as determined by indirect fluorescence, and some lymphocytosis, but no marked anaemia. Marmosets which had recovered from their primary infection (or in which it was drug-cured) suffered abbreviated patency with low-grade parasitaemia on re-infection.
Origins and organization of genetic diversity in natural populations ofTrypanosoma brucei
Authors: Cibulskis R. E. 
Published: June 2009

SummaryExperimental work has established that a sexual process can occur in African trypanosomes (Jenni, Marti, Schweizer, Betschart, Le Page, Wells, Tait, Paindavoine, Pays & Steinert, 1986; Paindavoine, Zampetti-Bosseler, Pays, Schweizer, Guyaux, Jenni & Steinert, 1986; Tait, personal communication). However, the role of the process in natural populations of trypanosomes is poorly understood. This paper considers what information can be gained from analyses of isoenzyme polymorphism. A cladistic approach is used to help determine whether trypanosome diversity could have been produced by mutation alone. When applied to three East African populations ofTrypanosoma bruceiit provides evidence that some diversity has arisen through a sexual process; this explains the variation observed within a locality and can account for the evolution of differences between localities. However, the extent to which genetic exchange currently operates is less clear. Analysis of genotype frequencies indicates that agreements with Hardy-Weinberg expectations can be obtained even if genetic exchange exerted no influence over genotype frequencies. Moreover, analysis of joint locus frequencies reveals disequilibrium between loci and that trypanosome populations may be lacking several genotype combinations. Thus, genetic exchange may not occur sufficiently frequently, or in such a way as to break up associations between loci. The relevance of these observations to the evolution of strain differences withinT. bruceiis discussed.
Attempts to protect goats against challenge withTrypanosoma vivaxby initiation of primary infections with large numbers of metacyclic trypanosomes
Authors: Vos G. J. , Moloo S. K. , Nelson R. T. , Gardiner P. R. 
Published: June 2009

SummaryAttempts were made to immunize goats by infection with large numbers of metacyclic trypanosomes of a clone ofTrypanosoma vivax, followed by chemotherapy. Five groups of 6 goats each were infected intradermally with 5 different doses of cultured metacyclics ofT. vivax, ranging from 102to 106trypanosomes/goat. Four weeks after infection, the goats were treated with 10 mg/kg diminazene aceturate (Berenil, Hoechst A.G.). Three weeks after treatment, 3 goats in each group were challenged intradermally with 104homologous metacyclics derived from culture. The remaining 3 goats in each group were challenged by 20 tsetse infected with the homologous clone. Five out of 30 goats were resistant to homologous challenge; 4 of the goats that had been challenged with cultured parasites, and 1 that had been challenged by tsetse. In each group 1 goat was protected. Protection was therefore not apparently influenced by the number of trypanosomes used to establish the primary infection. In another experiment, 6 goats were each infected by feeding 100 tsetse on the goats for 15 consecutive days. Three weeks after infection the goats were treated with Berenil and 3 weeks later challenged by 20 tsetse infected with the homologous clone. Three out of the 6 goats resisted challenge. The susceptible goats in both experiments, however, showed a reduction in the peak of parasitaemia following challenge compared with both challenge controls and the initial infections. Lytic antibodies to cultured metacyclics ofT. vivaxwere detected in goats that resisted challenge after a primary infection with cultured metacyclics, and in resistant and susceptible goats after a primary infection by tsetse. All infected goats produced lytic antibodies to live bloodstream forms, as well as antibodies to bloodstream form lysates (demonstrated by ELISA). It is suggested that the immunity that had been induced in some of the experimental animals is due to antibody responses to both metacyclic and bloodstream variable antigen types (VATs) expressed during infection.
The host—parasite relationship ofSchistosoma haematobiumin CBA mice
Authors: Agnew A. M. , Lucas S. B. , Doenhoff M. J. 
Published: June 2009

SummaryThe host—parasite relationships of two geographical isolates ofSchistosoma haematobiumin CBA mice are described and compared to previous reports on this parasite in other experimental hosts and in man. The mean percentage establishment of worms in mice was 17% and was not affected by the age or sex of the host. Adult worm burdens remained constant over 20 weeks, but were reduced after 18 months of infection. Male and female worms reached mean maximum lengths of 4·78 and 5·9 mm respectively. Egg laying commenced 9·5 weeks after infection and eggs accumulated in the tissues throughout the period of infection. A large increase in the rate of egg accumulation occurred coincidental with the appearance of eggs in the bladder of some mice. Faecal eggs were first observed in some mice at 12·5 weeks and most mice excreted a few eggs by 17 weeks p.i. (post-infection). Eggs were not found in the urine of infected mice. Excreted eggs and eggs isolated from the livers of infected mice hatched, but the resulting miracidia were unable to infect appropriate snail hosts. The development of hepatic granulomas and egg-induced pathology in the bladder of mice is described.
Effect of repeated anthelmintic treatment on ability to detect predisposition of mice to Heligmosomoides polygyrus and Aspiculuris tetraptera (Nematoda) infections
Authors: Scott Marilyn E. 
Published: June 2009

SummarySeveral recent studies have demonstrated predisposition of certain humans to heavy gastro-intestinal nematode infections. This finding has been used to support the concept of community control of nematodes based on selective treatment of the few heavily infected individuals in the community. A mouse model has been used in this study to determine whether those individuals found to be ‘predisposed’ to heavy infection continue to regain heavy nematode infections following repeated anthelmintic treatments. Re-infection was examined over 3 intervals of 8 weeks in 52 mice and individual worm burdens attained following drug-induced expulsion were analysed. In the case of Heligmosomoides polygyrus, parasite numbers obtained after first treatment were only significantly correlated with those obtained after the second treatment. Re-infection levels in mice during the second and third re-infection periods did not correlate with parasite loads at the beginning of the study. In the case of Aspiculuris tetraptera, correlations after each re-infection period remained significant, although the magnitude of the correlation coefficient decreased with successive re-infection intervals. The data suggest that a selective control programme based on repeated screening to identify heavily infected individuals prior to each treatment would reduce the number of H. polygyrus in the host population 17–6% more than a single screening at the beginning of the control programme, and would reduce the number of A. tetraptera by 14% more than a single screening. Re-infection rates for H. polygyrus were shown to decrease with increasing mouse age whereas re-infection rates for A. tetraptera increased with increasing mouse age.
Study on genetic polymorphism of Leishmania infantum through the analysis of restriction enzyme digestion patterns of kinetoplast DNA
Authors: Angelici M. C. , Gramiccia M. , Gradoni L. 
Published: June 2009

SummaryTwenty-nine Leishmania infantum strains characterized by different host source, tropism and belonging to 6 zymodemes, were examined by restriction enzyme analysis of kinetoplast DNA (kDNA) using 15 endonucleases. The enzymes which produced only one fragment revealed full identity between all the strains examined, while those producing many bands gave different electrophoretic patterns. They were interpreted with the aid of numerical analyses (cluster and multifactorial analysis). The results show a cline of genetic variability among the strains, the highest similarity being observed between most of the viscerotropic strains isolated from man, dog, black rat and sandflies. The strain agents of human cutaneous leishmaniasis show a varying degree of genetic divergence from this group, which appears more evident when characters from isoenzymes are considered.
Resistance to Millettia molluscicide in Biomphalaria glabrata: a quantitative genetical approach
Authors: Lam P. K. S. , Whitfield P. J. , Edge H. 
Published: June 2009

SummaryThis paper demonstrates the use of a quantitative genetical technique to assess genetic variance in molluscicide resistance in a Millettia thonningii-Biomphalaria glabrata system. Results indicated that there were significant genetic variances in both snail size and survival time in 10 p.p.m. molluscicide suspension. The possibility of wider applications of this technique in examining the genetic basis of molluscicide or pesticide resistance in target species is discussed.