bluuebunny/crossref_metadata_2025 huggingface dataset:
Nutrition support and the human immunodeficiency virus (HIV)
Authors: Bell S. J. , Mascioli E. A. , Forse R. A. , Bistrian B. R.
Published: June 2009

Nutritional support of patients with HIV or acquired immune deficiency syndrome (AIDS) has many similarities to other disease states in that the same nutritional products and techniques are used. Some patients with HIV, and many with AIDS without secondary infection, experience a metabolicmilieusimilar to patients with cancer cachexia. In providing dietary counselling to the HIV patient, we encounter many of the obstacles that must be overcome to improve nutrition in cancer: anorexia, gastrointestinal discomfort, lethargy, and poor nutrient utilization, which limit the ability for nutritional repletion. When a secondary infection is superimposed on HIV, patients resemble more highly catabolic trauma patients or patients in the intensive care unit (ICU), where, despite aggressive efforts to feed, there is usually a net nitrogen wasting leading to the more rapid development of cachexia. However, even in this setting, feeding will limit substantially net catabolism when compared to total starvation. Because the nutritional needs of HIV patients vary greatly, individual strategies have to be designed as the patient moves through the stages of disease. Patients are generally able to consume adequate nutrition either as regular food or dietary supplements during the latency period of viral replication. Once secondary infections become prevalent, artificial diets administered by tube or by vein may be required during the period of active secondary infections, with dietary supplements often helpful during more quiescent periods. Patients with HIV are among the most challenging for clinicians providing nutritional support. Knowledge from treatment of patients with other diseases may be useful, but more data must be gathered on the unique aspects of aetiology and treatment of the anorexia, malabsorption, and ultimate wasting associated with AIDS.
Energy requirements in human pregnancy, in human nutrition and parasitic infection
Authors: Durnin J. V. G. A.
Published: June 2009

The energy requirement of pregnancy reflects a problem which contains a great deal of uncertainty. To supply the theoretical energy needs for the increases in maternal and foetal tissues and to cover the elevated basal metabolic rate involves an amount equivalent to an extra 250–300 kcal/day on average, but in real-life situations there is seldom a rise in dietary energy of a comparable quantity. Data from co-ordinated longitudinal studies in four countries, together with results from other published papers, show energy intakes increasing by only 100–150 kcal/day, and only in the third trimester. Although it is difficult to demonstrate, the probability is that there are energy savings in reduced physical activity which compensate for the larger energy needs.
Biochemistry and molecular genetics of Leishmania glucose transporters
Authors: Langford C. K. , Burchmore R. J. S. , Hart D. T. , Wagner W. , Landfear S. M.
Published: June 2009

Glucose is utilized as a significant source of metabolic energy by Leishmania parasites. This sugar is accumulated by the parasite via a specific carrier-mediated transport system located in the parasite membrane. Parasites may also contain another transporter that shuttles glucose between the cytoplasm and the glycosome, a membrane-bound organelle where the early steps of glycolysis occur. The transport systems of both the insect stage promastigotes and the intracellular amastigotes have been characterized and shown to have kinetic properties that are consistent with the different physio-logical environments of the insect gut and the macrophage phagolysosome. Several genes have been cloned from Leishmania species which encode proteins with substantial sequence similarity to glucose transporters from mammals and lower eukaryotes. Two of these genes are expressed preferentially in the promastigote stage of the life cycle, where glucose is more readily available and more rapidly transported and metabolized than in the intracellular amastigotes. One of these two developmentally-regulated genes has been functionally expressed in Xenopus oocytes and shown to encode a glucose transporter. A third gene encodes a protein that is also a member of the glucose transporter family on the basis of sequence similarity and proposed secondary structure. However, the significant differences between this protein and the other two suggest that it is likely to transport a different substrate. Functional expression will be required to define the specific biochemical role of each gene within the parasite.
Evolutionary pressures in the spread and persistence of infectious agents in vertebrate populations
Authors: Anderson R. M.
Published: June 2009

Infectious agents have considerable potential to regulate or constrain the population growth of vertebrate hosts in natural habitats. A broad theoretical framework provides many insights into how the biology of the parasite and the demography of the host interact to determine this impact. It may manifest itself as a steady influence over time via stable endemic infection or in a recurrent epidemic fashion, sometimes with unpredictable intervals between epidemics depending on the generation time of the pathogen (time from infection to recovery or host death), its ability to induce lasting immunity and the population growth rate of the host species. Building on these notions, the paper focuses on recent work on the population dynamics of genetically variable pathogen populations and examines the factors that determine the evolution of virulence and the maintenance of genetic diversity in both host and pathogen. Recent research extends conventional theoretical templates to include population genetic elements and the within-host dynamics of the parasite and its interaction with the vertebrate immune system.
Patterns of macroparasite abundance and aggregation in wildlife populations: a quantitative review
Authors: Shaw D. J. , Dobson A. P.
Published: June 2009

In this paper we review the published literature on patterns of abundance and aggregation of macroparasites in wildlife host populations. We base this survey on quantitative analyses of mean burden and a number of measures of the degree of aggregation of parasite burdens between hosts. All major parasite and vertebrate host taxa were represented in the database. Mean parasite burden was found to be log-normally distributed, indicating that all parasite burdens are regulated to some degree. In addition, all but one of the parasitic infections were aggregated with respect to their hosts, and the relationship between log mean parasite burden and log variance was found to be very strong (R2= 0·87). That is, for a given mean parasite burden there are constraints on the degree of variation in individual host burdens. The aggregated nature of the parasitic infections is also apparent from other measures of the degree of aggregation: prevalence – mean relationships, and the negative binomial parameter,k. Using a relatively new technique for parasitological infection data – tree-based models, as well as traditional linear models – a number of the parasitic infections was found to be associated with systematically lower or higher parasite burdens. Possible biological explanations for these and other patterns are proposed.
Parasitic disease in amphibians: control by the regulation of worm burdens
Authors: Tinsley R. C.
Published: June 2009

This review considers three case studies based on macroparasites of anurans: (a) natural infections in the permanently-aquaticXenopus laeviswhich represent the worm burdens acquired, and the implications for pathology, when hosts are exposed to continuous, year-round, transmission; (b) the desert toad,Scaphiopus couchii, which experiences invasion very briefly each year and provides a simplified system involving only a single significant infection (Pseudodiplorchis americanus); (c) the mesicBufo bufowhich has been the subject of experimental laboratory studies designed to measure the effects ofRhabdias bufonisinfection on host growth, physical performance and survival. Experimental manipulation of bothScaphiopusandBufoprovide quantitative data on disease effects of macroparasites, including precise measurements of parasite-induced host mortality. Field data forXenopusandScaphiopusshow that, despite high initial worm burdens from efficient transmission, infection levels at parasite maturity are modulated below those leading to significant disease. Experimental data forScaphiopusandBufohave documented the time-course and magnitude of this decline in intensities, and there is circumstantial evidence forScaphiopusthat this regulation is host-mediated. Immunological studies onXenopusshow that disease effects of the pathogenicPseudocapillaroides xenopodisare exacerbated in thymectomised hosts and reversed by implantation of thymuses from MHC-compatible donors. Thus, whilst factorial experiments can demonstrate the potential of helminths to cause significant disease and mortality in anuran host-macroparasite interactions, powerful post-invasion regulation of worm burdens appears to exert a strong control of parasite-induced disease in natural host populations.
Antibodies to synthetic peptides based on band 3 motifs react specifically withPlasmodium falciparum(humanmalaria)-infected erythrocytes and block cytoadherence
Authors: Crandall I. , Sherman I. W.
Published: June 2009

Rabbit polyclonal and mouse monoclonal antibodies (Mabs) prepared against synthetic peptides patterned on exofacialloops 3 (amino acids 546–555) and 7 (821–834) of the human anion transport protein band 3 inhibited the cytoadherence ofPlasmodium falciparum-infected erythrocytes to C32 amelanotic melanoma cells. Mabs directed against exofacial loop4 (amino acids 628–642) did not inhibit adherence to a significant degree. The murine Mabs recognized onlyP. falciparum-infected erythrocytes suggesting that the epitopes of loops 3, 4 and 7 are normally cryptic in uninfected erythrocytes.
Ricin-resistant mutants ofLeishmania majorwhich express modified lipophosphoglycan remain infective for mice
Authors: Cappai R. , Morris L. , Aebischer T. , Bacic A. , Curtis J. M. , Kelleher M. , McLeod K. S. , Moody S. F. , Osborn A. H. , Handman E.
Published: June 2009

Glycosylation variants of the virulentLeishmania majorclone VI21 were generated by mutagenesis withN-methyl-N-nitroso-N-nitroguanidine and selected using the galactose-specific lectinRicinus communisII (RCA II). Three mutants, 4B9, 1D1 and 1C12, which failed to bind RCA II, were found to have an altered expression of lipophosphoglycan (LPG), a molecule implicated in the attachment to host macrophages and survival within the phagolysosome. There were differences in the antigenicity, molecular weight and localization of LPG from mutant parasites as compared to V121. Expression of gp63, a surface molecule also implicated in attachment to macrophages, was unaltered. All 3 mutants caused disease when injected into genetically susceptible BALB/c mice but lesions developed at a much slower rate than those caused by the virulent V121 clone. This slow rate of lesion development did not correlate with promastigotes' ability to invade macrophagesin vitro. Karyotype analysis showed that there was a reduction in the size of chromosome band number 2 in all 3 mutants. The differences in LPG and chromosome band 2 were retained by mutant clones following passage through mice, suggesting that these phenotypes are stable. Although the mutant parasites were infective and caused lesions, the changed structure of the LPG appeared to influence the virulence of the parasites.
Prevalence and transmission of Toxoplasma gondii in wild brown rats, Rattus norvegicus
Authors: Webster J. P.
Published: June 2009

Prevalence of Toxoplasma gondii within 6 UK farmstead wild rat populations, and 1 population maintained within a captivecat-free environment for 2·5 years, was examined. The mean prevalence found was 35% (n = 235), which is more than 3 times as high as all other wild rat prevalence levels previously reported in the UK. There were no significant age, sexor site differences in prevalence between or within populations irrespective of habitat type or presence of cats. Toxoplasma was also maintained within the captive rat population in the absence of cats at a prevalence, intensity, age and sexdistribution similar to that of the farmstead rat populations. These results suggest, firstly, that Toxoplasma can beperpetuated within wild rat populations without the sympatric presence of cats and secondly, that the congenital route isthe predominant route of transmission in wild rats. This study concludes that wild rats represent a significant and persistent wildlife intermediate host reservoir for toxoplasmosis.
Inhibition ofPlasmodium falciparumlysophospholipase by anti-malarial drugs and sulphydryl reagents
Authors: Zidovetzki R. , Sherman I. W. , Prudhomme J. , Crawford J.
Published: June 2009

The activity of lysophospholipase of human erythrocytes increased by about 3 orders of magnitude upon infection withPlasmodium falciparum. The apparentKmfor hydrolysis of lysophosphatidylcholine by this enzyme was 50 ± 7μM and the apparentVmax6·8±0·6 nmol/h × 106cells. The activity was Ca2+independent and had a broad pH maximum at pH 8. The enzyme was insensitive to such anti-malarials as mefloquine and arteether and was only weakly inhibited by chloroquine, with a 50% inhibition concentration (IC50) of 70 mM. The anti-malarials quinine and quinacrine were more efficient inhibitors, with IC50s of 2·6 mM and 0·7 mM, respectively. The sulphydryl agentsp–hydroxymercuribenzoate (pHMB) and thimerosal were considerably more potent, inhibiting the plasmodial lysophospholipase with IC50s of 18 μM and 10 μM, respectively. When present at 10 μM prior to invasion, both pHMB and thimerosal arrested the growth and reinvasion capacity ofP. falciparumin culture. In a synchronizedP. falciparumculture the continuous presence of 5 μM thimerosal dramatically decreased total parasitaemia and, within 4 days, totally abolished the capacity of the surviving parasites to reinvade. Thus the plasmodial lysophospholipase may represent a potential new target for anti-malarial chemotherapy.
Immunochemical studies on the cercarial-specific calcium binding protein ofSchistosoma mansoni
Authors: Ram D. , Romano B. , Schechter I.
Published: June 2009

Stage-specific expression of the mRNA encoding the cercarial-specific 8 kDa CaBP has been described previously. To gain information on possible function(s) of this protein we raised antibodies to the CaBP in rabbits immunized with a CaBP-TrpE fusion protein synthesized in bacteria. Western blots showed high levels of CaBP in cercariae and 3 h schistosomula, trace amounts in 24 h schistosomula, and none in miracidia sporocyst and adult worm, as found for the mRNA. The CaBP molecule has a short half-life (≤4 h) similar to that of the mRNA. Other experiments demonstrate that the CaBP may interact with a putative target molecule in a calcium-dependent manner to form a complex of 45 kDa. Immunogold electron microscopy showed CaBP in selected regions of cercariae and 3 h schistosomula: tegument, head gland, subtegumental cells, flame cells, intestinal wall and the body-tail junction. Other investigators have shown that the head gland and subtegumental cells synthesize and translocate granules to the tegument during transformation from cercariae (living freely in water) to schistosomula (residing in vertebrate host). These observations and the time-course of CaBP detection suggest that the CaBP synthesized in the head gland and subtegumental cells is translocated to the tegument where it plays a role in tegument modifications required for adaptation to parasite life in the host. CaBP was not found in muscles and mitochondria, suggesting that it is not involved in the rapid motility and aerobic metabolism characteristic of cercariae.
Molecular genetic characterization of the cervid strain (‘northern form’) ofEchinococcus granulosus
Authors: Bowles J. , Blair D. , McManus D. P.
Published: June 2009

We have used a number of molecular genetic approaches to characterize the cervid strain (‘northern form’) ofEchinococcus granulosus.PCR–RFLP analysis of the nuclear ITS1 region of the rDNA repeat can readily distinguish the cervid form from other strains ofE. granulosus. The complexity of the RFLP patterns obtained suggests that a number of distinct ITS1 types are present in this strain which may represent an inter-strainE. granulosushybrid. Mitochondrial CO1 sequence of the cervid genotype was ambiguous at 18 positions and closely resembles a cluster of previously characterizedE. granulosusgenotypes, G1 (common, domestic sheep)/G2 (Tasmanian sheep)/G3 (buffalo). In contrast, mitochondrial ND1 sequence, although unique, suggests that the cervid form is most similar to strains represented by the G6 (camel)/G7 (pig) genotypes. We assume that the CO1 and ND1 sequences obtained for the cervid genotype are linked in a single mitochondrial genome although this is difficult to explain if conventional molecular genetics of mitochondrial DNA are assumed. Based on its unique ND1 sequence and ITS1 PCR–RFLP pattern, the cervid strain appears to represent a distinct genotype (designated G8) ofE. granulosus.
Microscopical observations on immune precipitates formedin vitroon the surface of hymenolepid tapeworms
Authors: Hoole D. , Andreassen J. , Birklund D.
Published: June 2009

Four-day-old worms of the tapewormsHymenolepis microstoma,H. diminutaandH. nanaand newly excystedH. microstomawere exposed in vitro at 37 °C to immune serum from mice infected for 4–1 2 weeks withH. microstoma. Worms were fixed for electron microscopy after intervals of 5 min to 96 h. Within 10–15 min an homogeneous precipitate occurred between the microtriches of 4-day-oldH. microstomaandH. nana, while on some areas ofH. microstomathe precipitate extended distal to the microthrix border and contained small vesicles (30 nm in diameter) and shed microtriches. InH. diminutaprecipitates were not found until 2 h post-incubation. The thickness of the precipitate and the number of small vesicles and shed microtriches increased with time after incubation. Since a similar precipitate occurred on worms kept in complement-depleted immune serum, antibodies alone may induce immune damage. The precipitate on newly excystedH. microstomalacked microthrix fragments. After 48 h an extensive precipitate was found protruding from the rostellar glands on someH. microstoma, and within the culture vessel. Antibodies may therefore be complexing with tapeworm secretory products.
Relationships between Plasmodium falciparum infection and morbidity in a highly endemic area
Authors: Smith T. , Genton B. , Baea K. , Gibson N. , Taime J. , Narara A. , Al-Yaman F. , Beck H.-P. , Hii J. , Alpers M.
Published: June 2009

A total of 736 outpatients diagnosed as having malaria using clinical criteria at a health centre in a highly endemic area of Papua New Guinea were investigated parasitologically. Plasmodium falciparum-attributable fractions were determined using a logistic regression model to compare parasite densities in cases with those of healthy individuals in community surveys. Thirty-seven percent of presumptive cases were found to have raised P. falciparum parasitaemia. This corresponds to an average reporting rate for the population of 0·53 attributable episodes per annum. Whilst the maximum prevalence of parasitaemia in the community was in children aged 5–9 years, the maximum age-specific incidence of attributable cases at the outpatient clinic was 2 cases per annum in the 2- to 4-year-old age group. The procedure for estimating attributable fractions makes it possible to compare morbidity rates between age groups, and to examine how the relationship between morbidity risk and parasite density changes with age, without diagnosing individual episodes. The average tolerance of parasites in an age group was measured by considering the level of parasitaemia associated with a given risk of malaria-attributable morbidity. In contrast to anti-parasite immunity, tolerance of parasites declines with age since at parasite isodensity the probability of being symptomatic increases with age.
Tissue expression of theSchistosoma mansoni28 kDa glutathioneS-transferase
Authors: Porchet E. , McNair A. , Caron A. , Kusnierz J. P. , Zemzoumi K. , Capron A.
Published: June 2009

The expression of theSchistosoma mansoni28 kDa glutathione S-transferase (Sm28) was studied using molecular (PCR,in situhybridization), and immunocytochemical techniques. The presence of Sm28 was demonstrated in all developmental stages of the parasite except the intra-uterine immature egg. In the parenchyma of male and female adult worms the distribution of Sm28 was limited to a subpopulation of parenchymal cells and to the dorsal tubercles of the male. The tegument, the muscles, the digestive tract, the neural mass, the vitelline glands, and mature gametes were not immunoreactive. Immature germinal cells in both sexes, and the ootype in the female genital system, were found to express Sm28. Deposits of immunoreactive material on host skin following cercarial penetration, exfoliation from the male tubercles, and especially emission of Sm28 from eggs in hepatic granulomas are suspected to be a source of antigen during the parasite infection. The reduction in worm fecundity previously observed in immunization experiments may result from an antibody response directed against Sm28 present in the ootype. There was no cross-reactivity observed, under the experimental conditions used, between the anti-Sm28 sera and either vertebrate or invertebrate host tissue.
The interaction ofTrypanosoma congolensewith endothelial cells
Authors: Hemphill A. , Frame I. , Ross C. A.
Published: June 2009

Factors which affect adhesion of culturedTrypanosoma congolensebloodstream forms to mammalian feeder cells have been examined. Using anin vitrobinding assay, the initial events following interaction of trypanosomes with bovine aorta endothelial (BAE) cells were monitored by both light- and electron microscopy. Metabolic inhibitors and other biochemicals were incubated with either cells or parasites, to test whether any inhibited the process. Our findings suggest that adhesion of the parasites is an active process requiring metabolic energy from the trypanosomes, but not from endothelial cells. We also provide data suggesting thatT. congolensebloodstream forms possess a lectin-like domain, localized at distinct sites on their flagellar surface, which interacts with specific carbohydrate receptors, most likely sialic acid residues, on the endothelial cell plasma membrane. We also suggest that the cytoskeletal protein actin is probably involved in this interaction.
Heterogeneity in patterns of malarial oocyst infections in the mosquito vector
Authors: Medley G. F. , Sinden R. E. , Fleck S. , Billingsley P. F. , Tirawanchap N. , Rodriguez M. H.
Published: June 2009

Oocyst prevalence and intensity have been recorded in 349 laboratory infections ofAnopheles stephensiwithPlasmodium berghei. Intensity and prevalence of infection are shown to be predictably related. The structure and heterogeneity in the infections has been analysed with the objective of describing the biological mechanisms by which the observed negative binomial oocyst distributions are generated. The analysis has revealed that the most likely processes lie within the population dynamic events of malaria within the mosquito, namely gametogenesis, fertilization and mortality. The distribution is similar in allPlasmodium– mosquito combinations examined so far, whether they are of laboratory (P. gallinaceuminAedes aegypti) or field (P. vivaxinAn. albimanusandP. falciparuminAn. gambiae s.l.andAn. funestus) origin. Further we conclude that there is competition between parasites in the vector. Oocyst frequency distribution analysis shows that under natural conditions of transmission intensity, and even under the best laboratory conditions, significant numbers (> 10%) offullysusceptible mosquitoes will not be infected under conditions where the mean infection is as high as 250 oocysts. Failure to infect is not therefore an absolute indicator of refractoriness. In assessing transmission data it is shown that sample sizes should not be less than 50, and ideally 100 mosquitoes, if reliable data are to be obtained. In the field it is suggested that difficulties in determining the low natural intensity of oocyst infections indicate that prevalence estimates are a useful and accessible parameter to measure. In determining the impact of transmission blocking mechanisms we predict that under conditions where high oocyst intensities prevail, large reductions in intensity will be required before a reduction in prevalence can be expected i.e. here it will be necessary to measure intensity of infection. Conversely, under conditions where low oocyst intensities prevail, a rapid reduction in prevalence will occur with little concurrent reduction in intensity i.e. prevalence determination will be the more sensitive estimate.
Immunization of pigs against infection with Schistosoma japonicum using ultraviolet-attenuated cercariae
Authors: Shi Y.-E. , Jiang C.-F. , Han J.-J. , Li Y.-L. , Ruppel A.
Published: June 2009

Since pigs are important in the zoonotic transmission of schistosomiasis japonica in China, a veterinary vaccine might contribute to the control of the disease in humans. Pigs were immunized with three doses each of 10000 cercariae of Schistosoma japonicum attenuated with ultraviolet light (400 μWatt·min/cm2). The experiment was performed with portable irradiation equipment in a rural area of the Hubei Province (P.R. China). A challenge infection of 1000 untreated cercariae was given 2·5 or 6 months after the last immunization, and age-matched naive pigs were challenged as a control. Immunized pigs developed about 90% resistance against the challenge. The liver egg load of these animals was reduced by over 90%. Less than 0·01 % of the immunizing cercariae developed to adult parasites and the vaccination had no apparent adverse influence on the pigs' health.
Mechanisms involved in the loss or antibody-mediated adherence of macrophages to lung-stage schistosomula ofSchistosoma mansoni in vitro
Authors: Lawson B. W. L. , Bickle Q. D. , Taylor M. G.
Published: June 2009

Sera from rabbits vaccinated with irradiated cercariae mediated cell (P388D1or mouse peritoneal macrophage) adherence to lung-stage schistosomula (LS) but such antibody-mediated cell adherence was short-lived in contrast to cell adherence to mechanically transformed schistosomula (MS). Thus LS lost 50% of their adherent cells within 3–6 h in culture and up to 90% by 24 h, whereas adherence to MS was undiminished during this time. Rapid loss of adherent cells was unique to schistosomula that had developed to the lung stage because schistosomula recovered from the skin up to 3 days post-infection did not exhibit the rapid cell loss shown by 3-day LS. To determine whether cell loss was caused by loss of surface antigenicity during culture LS were cultured on their own for up to 24 h and at various intervals samples of schistosomula were tested for antigenicity by addition of immune serum and cells. Levels of adherence to both MS and LS were maintained throughout the incubation period. When antibody-opsonized schistosomula were washed and indicator cells added at progressive intervals, persistence of adherence was again demonstrated, showing that antibody binding to LS had not promoted surface antigen loss or degradation of bound antibody. It was then shown, by adding fresh macrophages to cultures up to 24 h old that LS which had lost their adherent cells nevertheless retained bound antibody, and comparison of adherence of ‘used’ and ‘fresh’ cells to MS and LS showed that the cytoadherence properties of macrophages were not significantly reduced during their culture with LS from which cells had been lost. Cell loss was shown to be dependent upon protein synthesis by LS since cell loss was significantly reduced when the schistosomula were pre-incubated in puromycin or actinomycin D. Transient cell adherence to LS may comprise an important immune evasion stratagem by schistosomula.
Epidemiology of trypanosome infections of the tsetse fly Glossina pallidipes in the Zambezi Valley
Authors: Woolhouse M. E. J. , Hargrove J. W. , McNamara J. J.
Published: June 2009

The epidemiology of trypanosome infections of Glossina pallidipes was studied at a riverine site in the Zambezi Valley, Zimbabwe for a period of 13 months. Over 9000 flies were captured using a single trap. These flies were dissected, screened for trypanosome infection, sexed, and aged using both wing fray and (for females) ovarian category indices. Midgut infections were identified to species using recently developed DNA probes. The overall prevalence of mature infections was 5·5%, comprising 3·1% Trypanosoma vivax-type and 2·4% T. congolense-type (which included very low prevalences of T. brucei, T. simiae and another Nannomonas species). The prevalence of infection increased with age. For T. vivax-type infections in flies aged by ovarian category this relationship could be described by a simple ‘catalytic’ model assuming a constant per capita rate of infection. For T. congolense-type infections this model tended to over-estimate prevalence in older age classes, implying that the rate of infection decreases with age, and/or that infected flies have higher mortality rates, and/or that a significant fraction of the population is resistant to infection. Prevalences of infection also varied between months. This variation was more marked for T. vivax-type infections and was negatively correlated with both temperature and rainfall. The shape of the age-prevalence relationship, however, did not vary significantly between months. These observations are not fully explained by variation in the age-structure of the tsetse population and are consistent with temporal variation in the rate of infection (rather than in the trypanosome developmental period or in effects of infection on fly mortality). Possible causes of this variation are discussed.
Spatio-temporal structure of the communities of helminths in the digestive tract of Sciaena umbra L. 1758 (Teleostei)
Authors: Holmes J. , Bartoli P.
Published: June 2009

The helminth community in the digestive tract of the sedentary predatory fish, Sciaena umbra, near the Scandola Nature Reserve, Corsica, consists of 5 species of digeneans. Anoiktostoma coronatum (in the rectum) and Metadena pauli (in the intestine) were found in almost all the fish, and in high numbers; they are considered core species. Distomum aloysiae, Pleorchis polyorchis (both in the intestine), and Stephanostomum bicoronatum (in the rectum) were relatively uncommon, usually found in small numbers, and are considered satellite species. The two core species were very abundant in June, when the size of their populations was strongly correlated with the size of the host fish. At this time, M. pauli was found mainly in the duodenum, but in high populations was spread throughout the intestine (s. strict.). Both species were much less abundant in October, their populations were less dependent on host size, and M. pauli was more limited to the anterior intestine. Pleorchis polyorchis and Distomum aloysiae were more frequent in October, were found predominately in fish with few M. pauli, and were found posterior to M. pauli, suggesting some interactions between these species. Stephano-stomum bicoronatum showed no seasonal patterns, and no apparent interactions with A. coronatum.
Asparaginyl endopeptidase activity in adultSchistosoma mansoni
Authors: Dalton J. P. , Hola-Jamriska L. , Brindley P. J.
Published: June 2009

Sequence comparisons have recently shown that theSchistosoma mansoniprotein Sm32 is similar to asparaginyl endo-proteinases, a novel family of cysteine proteinases, of which the legumains rom legumes are the best characterized. By synthesizing and employing fluorogenic peptide substrates for the specific detection of asparaginyl endopeptidases, we have identified this type of activity in extracts of adultS. mansoni. TheS. mansoniactivity is similar to that of the legumains in its substrate specificity and sensitivity to thiol inhibitors, but differs in its pH and temperature optima for activity. In contrast, unlike the legumains, the schistosome asparaginyl endopeptidase activity is not activated by the reducing agent dithiothreitol. As suggested for legumains, Sm32 may function in the post-translational modification processes that regulate the activity of other molecules.
Examination of the Steinernema feltiae (Site 76 strain) infection interaction with the Galleria mellonella host, using an infection model
Authors: Bohan D. A. , Hominick W. M.
Published: June 2009

Using a simple infection model the infection interaction of Steinernema feltiae (Site 76 strain) Filipjev and Galleria mellonella L. was investigated under laboratory conditions. The model analyses showed that the infection interaction was consistent with a proportion of the S. feltiae infective stages being infectious and, alone amongst the infective-stage population, being capable of infection. The investigation also showed that the infection behaviour of the infectious stages could be reduced to a slightly overdispersed probability of transmission. The importance of these findings with respect to the quantitative description and explanation of infection are discussed.
Erratum
Authors: Victoir K. , Dujardin J. C. , Doncker S. De , Barker D. C. , Arevalo J. , Hamers R. , Ray D. Le
Published: June 2009

Plasticity of gp63 gene organization in Leishmania (Viannia) braziliensis and Leishmania (Viannid) peruviana Parasitology (1995), 111, 265–273

Fig. 4 (p. 270) was wrongly orientated. It appears correctly below.

Fig. 4. RFLP analysis after digestion with Bgl I and hybridization with pLb-134Sp (A) or the 10 kb Not I/Bgl I recombinant fragment of cosmid clone B.3.4.2 (B). Isolates: Leishmania braziliensis M2904, 1; L. peruviana LC26, 2. Size is expressed in kb.
The excretory metabolism of the endoparasitic digeneanFasciola hepaticaand its relationship to its respiratory metabolism
Authors: Moss G. D.
Published: June 2009

The amounts of ammonia excreted by two endoparasitic flatworms have been compared and, weight for weight, the sheep liver flukeFasciola hepaticaproduces ten times as much ammonia as the rat tapewormHymenolepis diminuta. This is thought to reflect a difference in diet, the fluke feeding mainly on the blood and tissue proteins of its host, and the tapeworm mainly on carbohydrates from the food materials in the gut of the host. However, the addition of glucose to the saline in which the flukes are cultured produces a marked decrease in the ammonia and an increase in the lactic acid excreted, suggesting that flukes are not obligatory protein feeders but that they may utilize carbohydrate when it is available. The relatively low production of lactic acid when proteins are being metabolized suggests that the flukes are producing an alternative end-product of respiratory metabolism. It is possible that this is the neutral lipid found in the excretory system ofFasciolaand the possibility of an alternative metabolic pathway for the production of such lipid is discussed. The respiratory metabolism appears to be independent of oxygen, and the possible role of oxygen in other aspects of the metabolism of the fluke is discussed.

I should like to express my sincere gratitude to Dr J. Llewellyn for his constant advice and encouragement during the course of this work and the preparation of the manuscript. I also thank Professor 0. E. Lowenstein, F.R.S., for allowing me the use of the facilities in his department during the tenure of an S.R.C. Research Studentship. Finally, my thanks are due to Mr E. Wilson, the Veterinary Officer at the Birmingham City Meat Market, for his constant co-operation in obtaining supplies of liver flukes.
The penetration of human epidermal sheets by the cercariae of Schistosoma mansoni and the collection of schistosomula
Authors: Kusel J. R.
Published: June 2009

1. The percentage conversion of cercariae into schistosomula, when the former were penetrating human epidermal sheets, was found not to be significantly affected by the underlying media 1—5 (Table 1). The percentage conversion varied from 16·4% (in normal saline underlying skin) to 26.2 %. When distilled water was the underlying medium significantly fewer cercariae penetrated the sheets.

2. There was a statistically significant decrease in the percentage conversion of cercariae to schistosomula when sodium chloride final concentration 0·67 % was placed in the exposure tube with the cercariae (1·6 % P = < 0·02 when compared with La Ye medium); 0·43 % sodium chloride also significantly decreased penetration.

3. There was a statistically significant decrease in the percentage conversion of cercariae to schistosomula when the orientation of the human epidermis was reversed, i.e. the biologically inner surface was exposed to the cercariae (2.6 %, P = < 0.02, when compared with La Ye medium).

4. Schistosomula agglutinated in the presence of normal or immune human serum or horse serum. In human serum to which donor red blood cells had been added, many red cells adhered to the schistosomula. The number adhering was less in inactivated serum. The adhesion was specific for red cells, the effect not occurring with either yeast cells or silicic acid particles. The red cells were shed from the surface of the schistosomulum after 4—12 h.

I should like to thank the following: Dr S. A. Ibrahim, in whose laboratory this work was carried out; Dr S. Dawood of the Stack Laboratory, Khartoum for the use of his microscope; Mr T. R. Melrose and Mr J. R. Lauder for valuable discussions; the Medical Research Council, U.K., and the University of Khartoum for research grants. I am very grateful to the Pathology Department Faculty of Medicine, University of Khartoum, for preparing the sections of human epidermis.
Immunity to coccidiosis: effect of betamethasone treatment of fowls on Eimeria mivati infection
Authors: Rose M. Elaine
Published: June 2009

Daily 1 mg doses of a cortisone derivative, betamethasone, caused an increase in oocyst production and extended the patent period of E. mivati infections in partially immunized chickens. The more prolonged the course of cortisone injections, the greater the effect, although this was substantial when only a single dose was given, especially if this was at or near to the time of oocyst inoculation. E. mivati infections in susceptible chickens were similarly affected but not to such a great extent.

The possible means whereby cortisone treatment reduces acquired immunity to E. mivati infection are discussed.

Thanks are due to Mrs P. Hesketh and to other members of the parasitology department for technical assistance, also to the senior poultry attendant for care of the animals. Mr C. C. Wannop examined several of the birds post mortem.
Social behaviour and susceptibility to infection in house mice (Mus musculus): effects of group size, aggressive behaviour and status-related hormonal responses prior to infection on resistance toBabesia microti
Authors: Barnard C. J. , Behnke J. M. , Sewell J.
Published: June 2009

Associations between social rank, immunodepression and resistance toBabesia microtiinfection within single-sex groups of male house mice suggest rank-dependent suites of response involving different hormonal and immune changes in relation to aggressive behaviour and group size prior to infection. Reduced resistance among high-ranking males was associated with increased serum testosterone and corticosterone concentration and reduced serum immunoglobulin, but was independent of group size. Among low-ranking males, hormonal changes were not associated with resistance toB. microtibut changes in corticosterone concentration and measures of immunodepression increased with group size and aggressive behaviour. The results concur with earlier findings suggesting differences between high- and low-ranking mice in their physiological responses to social experience and consequently reduced resistance toB. microtiinfection among high-ranking individuals.
Aggregations of nematode parasites withinDrosophila: proximate causes
Authors: Jaenike J.
Published: June 2009

Macroparasites almost invariably exhibit overdispersed distributions of parasites/host, yet the specific causes of such aggregations remain poorly understood. The present study focused on the distribution of the parasitic nematodeHowardula aoronymphiumamong its hosts, several species of mycophagousDrosophila. The distribution of parasites/host is close to random for cohorts of flies of a given host species emerging from single mushrooms. At the level ofHowardulapopulations, overdispersion of parasites among hosts results primarily from variation among subgroups of hosts in their exposure to infective-stage nematodes. The sources of variation identified in this study includeDrosophilahost species, the site where flies bred, mushroom species within sites, and, most importantly, individual mushrooms within mushroom species at a site. For the mean intensity of parasitism observed in this study, the degree of aggregation is typical of macroparasites in general. Combinations of random distributions with different means, resulting from variation among groups in exposure to parasites, may be a common cause of the overdispersion of macroparasites among hosts.
Identification and characterization of the cysteine and serine proteinases of the trematode,Haplometra cylindraceaand determination of their haemoglobinase activity
Authors: Hawthorne S. J. , Halton D. W. , Walker B.
Published: June 2009

The excreted/secreted proteinases ofHaplometra cylindraceamaintainedin vitro, were found to hydrolyse the fluorogenic substrates, Z-ArgArg-NHMec and Z-PheArg-NHMec. This activity was shown to be typically that of cysteine proteinases, as turn-over of both substrates could be blocked by pre-incubation with peptidyl diazomethyl ketones. The biotinylated affinity reagent, biotin-Phe Ala-DMK, used in combination with Z-PheTyr(OBut)-DMK, was employed for the labelling and characterization of these cysteine proteinase activities. Three cathepsin B-like species were detected, with molecular weights of 48, 22–23 and 14 kDa, together with a cathepsin L-like enzyme, with a molecular weight of 55 kDa. The proteinases were also found to have hydrolytic activity towards the substrate, Z-GlyGlyArg-NHMec, which could be blocked by pre-incubation with either of the serine proteinase-selective reagents, Z-ArgP(OPh)2, or biotin-LysP(OPh)2, showing the activity to be trypsin-like. Using the biotinylated affinity label to characterize the trypsin-like enzymes revealed two molecular species with molecular weights of 20 and 24 kDa.
The fine structure of the alimentary tract of third-stage larvae of Haemonchus placei and Trichostrongylus colubriformis
Authors: Smith Kenneth , Harness Eric
Published: June 2009

A comparative study was made of defined regions of the alimentary tract of third-stage larvae of T. colubriformis and H. placei. The general organization of the tract was similar in both nematodes. The mouth, buccal cavity and oesophagus were lined with cuticle. Muscle cells, apical cells and gland cells were present in the oesophagus. In both species the gland cells contained secretory granules of similar morphology. The lumen of the intestine was ill-defined and apparently nonfunctional. Dense bodies observed in the intestinal cells differed in the two species.

We are grateful to Dr D. W. Brocklesby for his help and advice. We would also like to thank Dr D. L. Lee and Dr W. G. MacMillan for helpful discussions.
A study of acetylcholinesterase throughout the life cycle ofNippostrongylus brasiliensis
Authors: Sanderson Barbara E. , Ogilvie Bridget M.
Published: June 2009

Acetylcholinesterase activity, measured per unit wet weight, is relatively low in the eggs and infective larvae ofN. brasiliensis. It increases rapidly during the parasitic phase, especially in the late 3rd- and early 4th-larval stages. Activity in normal adults is extremely high (× 15 egg activity) and this is doubled again in immune-damaged adults. Possible functions ofN. brasiliensisacetylcholinesterase are discussed.

It is a pleasure to acknowledge the technical assistance of Miss Anne Cronin and Miss Beryl Crooks.
Acephaline gregarines of British earthworms–their possible host specificity
Authors: Segun A. O.
Published: June 2009

The host-specificity of monocystids was investigated experimentally by infesting infection-free Dendrobaena subrubicunda f. typica with sporocysts of Apolocystis megagranulata and A. lavernensis normally found in Dendrobaena subrubicunda and Allolobophora longa respectively. An attempt to infect worms raised free from infection with sporocysts of Monocystis agilis normally harboured by Lumbricus spp. was unsuccessful. Eighteen of the thirty identified monocystids were found to be monobiotic (species-specific), eleven were oligobiotic (genus-specific) and only one was polybiotic (family-specific).

The writer wishes to express his sincere appreciation to Dr Anne Terry for her advice and useful suggestions, and to Mr D. Etherington, the head of department, for his encouragements throughout the research period.
Molecular biology and electrophysiology of glutamategated chloride channels of invertebrates
Authors: Cully D. F. , Wilkinson H. , Vassilatis D. K. , Etter A. , Arena J. P.
Published: June 2009

In this chapter we summarize the available data on a novel class of ligand-gated anion channels that are gated by the neurotransmitter glutamate. Glutamate is classically thought to be a stimulatory neurotransmitter, however, studies in invertebrates have proven that glutamate also functions as an inhibitory ligand. The bulk of studies conductedin vivohave been on insects and crustaceans, where glutamate was first postulated to act on H-receptors resulting in a hyperpolarizing response to glutamate. Recently, glutamate-gated chloride channels have been cloned from several nematodes andDrosophila. The pharmacology and electrophysiological properties of these channels have been studied by expression inXenopusoocytes. Studies on the cloned channels demonstrate that the invertebrate glutamate-gated chloride channels are the H-receptors and represent important targets for the antiparasitic avermectins.
Some helminth parasites of Fishes of Bermuda and an account of the attachment organ ofAlcicornis carangisMacCallum, 1917 (Digenea: Bucephalidae)
Authors: Rees Gwendolen
Published: June 2009

Of 414 Bermuda fishes, 148 belonging to 13 species harboured Digenea and 11 belonging to 6 species Aspidogastrea, Acanthocephala or nematodes. In a previous paper 69 of these fishes belonging to 20 species were found to contain cestodes. The number of infected species was greatest in the case of cestodes and the number of infected individuals in the case of Digenea. The latter is probably due to the closer proximity, for reasonably long periods, of the various hosts in the life-cycles. Of the 17 species of Digenea 3 are new host records, 3 new locality records and 4 new host and new locality records. New records were found, also, in the other groups of helminths. The digenean fauna of Bermuda fishes most closely resembles that of Dry Tortugas, Florida. Digenea and cestodes were not usually found in the same families of fishes. Cestode larvae were abundant in the deep-water Serranidae and Lutianidae which had no Digenea, the latter being common in Clupeidae, Hae-mulidae and Belonidae, which do not harbour cestodes and which occur, mostly, in the inner reefs and shallows.

The functional morphology of the apical disk, tentacles and rhynchus ofAlcicornis carangisis described. The tentacles are invaginable and concerned with attachment.

I am most grateful to Dr W. H. Sutcliffe Jun., Director of the Bermuda Biological Station, for the excellent facilities provided and to The Shell Grants Committee and The National Science Foundation for grants which made the work possible. I would also like to express my gratitude to all those who kindly helped in the capture of fishes and to Mrs M. Fisher for technical assistance.