bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the absorption of amino acids by larval tapeworms (Cyclophyllidea: Taenia crassiceps)
Authors: Haynes W. D. G. , Taylor Angela E. R. 
Published: June 2009

Larvae of Taenia crassiceps have been shown to absorb L-valine and L-methionine by a process of active transport. Uptake is maximal at about 43 °C and a pH of about neutrality, and concentration against a gradient has been demonstrated. In advanced larvae, the absorption mechanism has been shown to be specific for neutral aliphatic amino acids, with an uncharged amino group in the α-position. Competitive inhibitions of uptake have been demonstrated in the presence of other amino acids.Comparison has been made with a mechanism present in Hymenolepis diminuta for the uptake of neutral amino acids, demonstrated by Read et al. (1963), and the absorption of L-methionine by the two species has been compared in detail.The uptake of valine and methionine by the two types of larvae has been compared in detail: the presence of two types of sites for the uptake of these aminoacids has been suggested.The absorption of the L-isomers of glutamic acid, proline, serine, glycine and leucine has been demonstrated in advanced larvae. Separate mechanisms for the uptake of acidic amino acids, basic amino acids and neutral aromatic amino acids have been suggested.Thanks are due to Professor G. Chapman, in whose department this work was carried out, and to Miss E. Clarry for her willing assistance. We would also like to thank Dr G. Ayrey, of the Queen Elizabeth College Isotope Unit, for his valuable help, especially in the development of a technique for the simultaneous counting of 14C and 3H. The work was supported by a research grant from the Wellcome Trustees, to whom we are most grateful.
Death of schistosome cercariae during penetration of the skin
Authors: Rai S. L. , Clegg J. A. 
Published: June 2009

The seagull, a natural host ofAustrobilharzia terrigalensis, was infected with cercariae through a small area of breast skin; 40% of the schistosomula recovered from the skin shortly afterwards were dead. In budgerigar skin 29% of the schistosomula were dead, but mortality in the skin of ducklings was much higher (85%). The budgerigar is a useful laboratory host for this schistosome, but ducklings are completely resistant to experimental infection mainly because of the barrier effect of the skin.Rapid recovery of schistosomula from budgerigar skin established that the majority of deaths occurred during the first 15 min after application of cercariae. In sections of skin fixed after 10 min nearly all the schistosomula were in the epidermis between the narrowstratum corneumand the living cells of the Malpighian layer. In seagull and budgerigar skin most schistosomula succeeded in crossing the Malpighian layer in the next 5 min, but in ducklings nearly all schistosomula completely failed to penetrate this layer.In vitroexperiments in which cercariae were allowed to penetrate through several layers of dead epidermis, isolated from dried budgerigar skin, into balanced saline, showed that schistosomula are not killed by host cells or a soluble toxic substance. The possibility that the epidermis contains an insoluble toxic substance could not be excluded.The proportion of schistosomula which died during penetration of dead epidermis was related to the number of layers in the barrier, suggesting that schistosomula may die owing to exhaustion caused by the intense activity of penetration.About 30% of the glycogen reserves of cercariae were utilized during penetration of budgerigar skin. In dead schistosomula the glycogen reserve had been reduced by 80%, but the significance of this observation is uncertain because much of the glycogen may have been autolysed after death of the schistosomula. Exposure of cercariae to glucose before penetration did not affect the proportion which died in the skin.Schistosomula adapt to the osmotic pressure in the skin, which is one-third that of sea water, and 30 min after penetration they are rapidly killed if returned to sea water. This process of adaptation is not related to mortality of schistosomula during penetration of the skin.We wish to acknowledge the expert technical assistance of Mrs J. Morgan. This investigation was supported in part by research grant AI-04707 from the National Institute of Allergy and Infectious Diseases, United States Public Health Service.
Circulating antibodies to histolysain, the major cysteine proteinase ofEntamoeba histolytica, in amoebic liver abscess patients
Authors: Osorio L. M. , Picóf T. , Luaces A. 
Published: June 2009

SUMMARYA solid-phase enzyme immunoassay (EIA) was used to detect circulating antibodies to histolysain, the major cysteine proteinase ofEntamoeba histolytica. Serum samples from 40 healthy controls, 33 asymptomaticE. histolyticacyst passers and 22 patients with amoebic liver abscess were tested. Antibodies to histolysain were found in 72·7% of cases of amoebic liver abscess, 18·1% of the cyst passers and 2·5% of healthy controls, which suggests that a humoral immune response is induced by histolysain during amoebic liver abscess.
The life cycle ofParvatrema homoeotecnumsp.nov.(Trematoda: Digenea) and a review of the family Gymnophallidae Morozov, 1955
Authors: James B. L. 
Published: June 2009

1.Parvatrema homoeotecnumsp.nov. from the oystercatcher,Haematopus ostralegus occidentalisNeumann at Aberystwyth is described and compared with other species of the genus.2. The life cycle of this species is unique. The larval stages occur in the gastropod,Littorina saxatilis(Olivi) subsp.tenebrosa(Montagu) and include germinal sacs which have a structure and development similar to an adult digenean. There are no free-living stages and only one intermediate host.3. The significance of this unique life cycle is discussed.4. The family Gymnophallidae Morozov, 1955, is reviewed. Emended definitions are given for the family, subfamilies and genera. Keys, diagnostic features and brief notes of the species are included.I am very grateful to Dr Gwendolen Rees, who suggested the investigation which led to the discovery of this species, for her advice and indispensable assistance throughout the work and the preparation of this paper. I am also grateful to the late Professor T. A. Stephenson for his interest and for the provision of working facilities; to Mr W. A. Ballantine, Mr A. H. Clarke, Jr., Mr C. Curtis, Miss G. P. F. Evans, Dr V. Fretter, Professor L. A. Harvey, Mr D. H. Jones and Dr J. Lewis who sent me specimens ofLittorina saxatilis; to Professor R. M. Cable and Emerit. Professor G. R. La Rue for helpful suggestions; to Mr J. R. Hirst and Mr D. Hemingway Jones for photographic and technical assistance and to the Department of Scientific and Industrial Research for a grant which made the work possible.
Microtubular organization visualized by immunofluorescence microscopy during erythrocytic schizogony in Plasmodium falciparum and investigation of post-translational modifications of parasite tubulin
Authors: Read M. , Sherwin T. , Holloway S. P. , Gull K. , Hyde J. E. 
Published: June 2009

SUMMARYWe describe a novel procedure for the immunofluorescent investigation of Plasmodium falciparum. This has allowed us to visualize clearly microtubular structures and their changing conformation through the erythrocytic cell-cycle, to the stage of cytodifferentiation leading to merozoite release. The images of spindle development we observed, together with an analysis of nuclear body numbers in large numbers of parasites, indicate that there is an apparent asynchrony in chromosomal multiplication within a single parasite. Using antibodies specific for post-translational modification of α- tubulin, we also demonstrate that the C-terminal tyrosine-containing epitope of P. falciparum α-tubulin I is similar to that of other organisms. Lysine-40 in the same molecule, a target for highly specific in vivo acetylation in some organisms, is unmodified in the blood stages we examined here. After in vitro acetylation of this residue, however, the epitope to which it contributes was recognized by antibody, showing that the conformation of this part of the molecule is also conserved, despite a lack of primary sequence homology immediately downstream of the target lysine residue.
Decoy effect and host infection by miracidia within snail communities
Authors: Chipev N. H. 
Published: June 2009

SUMMARYThe effect of experimental non-host snail (NHS) communities on the infection of Lymnaea truncatula with Paramphistomum daubneyi and Fasciola hepatica miracidia was studied. The results obtained indicated that NHS had variable effects on basic population parameters of host infection. Specifically, NHS were able to produce aggregation of sporocyst number/snail in the experimental host populations. Proposed hypotheses for decoy effect mechanisms failed to explain completely the experimental results. A new mechanism is suggested, based on a distance response of miracidia to snail chemo-attractants, to explain effects of NHS on miracidial host finding behaviour. It is assumed that miracidia have evolved the ability to discriminate among individual snail chemical attractants in a community already at a distance. This attribute of miracidial behaviour allows NHS to induce variations in the effectiveness of individual host localization by miracidia. The resulting aggregation of successful infections/host is assumed to be the specific component of snail decoy effect at the community level. It was also established that NHS affected trematode reproduction in the host inducing a compensatory increase in the intramolluscan population. Intraspecific competition among developmental stages is suggested to be the mechanism of this compensatory reaction.
Field trials in the control of Opisthorchis viverrini with an integrated programme in endemic areas of northeast Thailand
Authors: Saowakontha S. , Pipitgool V. , Pariyanonda S. , Tesana S. , Rojsathaporn K. , Intarakhao C. 
Published: June 2009

SUMMARYA control programme of opisthorchiasis was carried out for three years in three villages of northeast Thailand in order to compare the effectiveness of two intervention measures. The intervention measures employed were to give praziquantel treatment to all infected people either once (village I) or twice (village II) per year with the integration of regular health education and sanitation improvement. A control village (village III) received no intervention during the study. Sampling of the population in these villages to estimate prevalence, intensity, reinfection and incidence of infection as well as knowledge of opisthorchiasis and number of latrines was performed at 6 monthly intervals throughout the duration of the study. At the initial assessment, there were no significant differences in the prevalence and intensity of infection of villages I and II. Both values were greatly reduced when assessed 6 months after the initiation of treatment, and the decrease in prevalence and intensity of infection did not differ between villages I and II. The control village (village III), during the first 2 years, exhibited slight variation in the prevalence and intensity, and these decreased considerably in the third year of the study. The reinfection rate per 6 months in villages I and II was nearly equal. The incidence rate per 6 months in the two treated villages was lower than that of the control village. Marked improvement in knowledge of opisthorchiasis, behavioural changes of eating raw fish and increased numbers of latrines was evident in all of the villages during this study. The study showed that the effectiveness of annual drug treatment is similar to that of 6 monthly treatments when combined with regular health education and sanitation improvement.
Intestinal helminth communities of the long-finned pilot whale (Globicephala melas) off the Faroe Islands
Authors: Balbuena J. A. , Raga J. A. 
Published: June 2009

SUMMARYThe intestines of 170 long-finned pilot whales, Globicephala melas, caught off the Faroe Islands (N.E. Atlantic) were examined for helminth parasites. Eight species were detected but only 4 occurred in at least 10% of the sample. No core or recurrent group of species were identified and no correlations between abundances of species were significant. Diversity values were far below those reported for other endotherms. Colonization by helminths was random, whales not being readily colonized. These features point to largely unpredictable, isolationist infracommunities, there being little potential for inter-specific interactions. Older hosts tended to harbour more diverse infracommunities, offering more opportunities for such interactions. Two hypotheses, which might also apply to other cetaceans, are proposed to account for the depauperate helminth communities of the pilot whale: (i) some ancestral helminth species failed to adapt their cycles to the marine habitat and (ii) the hosts' isolation from land prohibited new infections with helminths of mammals.
Chemotherapy and immunity in opportunistic parasitic infections in AIDS
Authors: Zumla A. , Croft S. L. 
Published: June 2009

SUMMARYParasitic diseases are endemic in parts of the tropics, but there is no convincing evidence that their prevalence or incidence is increasing due to the HIV epidemic. Available scientific data on parasitic infections in patients with the Acquired Immunodeficiency Syndrome (AIDS) suggests a predominance ofPneumocystis carinii, Toxoplasma gondiiandCryptosporidiumspp. For reasons which are unclear, parasitic infections such asPlasmodium falciparum, Strongyloides stercoralisandEntamoeba histolytica, where cell-mediated immune responses are also thought to be significant, do not appear to be opportunists of importance. It is being increasingly recognized that chemotherapy for parasitic diseases has a host-dependent component, although scientific data on this subject remain scanty. The management of opportunistic parasitic infections in patients infected with HIV is dogged by failures and relapses, aptly illustrating the notion of the relationship between chemotherapy and the immune response. This review discusses the immunity and chemotherapy of opportunistic parasite infections in patients infected with the Human Immunodeficiency Virus (HIV).
Resistance to intestinal parasites during murine AIDS: role of alcohol and nutrition in immune dysfunction
Authors: Watson R. R. 
Published: June 2009

SUMMARYA murine AIDS model with many similarities to human AIDS, LP-BM5 Murine Leukaemia, suppresses T and B cell numbers and functions in the intestine. This permits chronic colonization by Giardia and Cryptosporidium. Cocaine and the nutrient alcohol, which are immunosuppressive, further reduce resistance to intestinal parasites and intestinal lymphocyte numbers. Protein undernutrition, vitamin E supplementation, and alcohol use further modify immune dysfunction induced by the murine retrovirus infection. This suggests that both undernutrition and nutrient supplementation could affect parasite resistance during AIDS. Thus this murine model of human AIDS has great potential to accelerate studies of the role of nutrients in immune dysfunction and resistance to intestinal parasites.
Evolutionary ecology of vertically transmitted parasites: transovarial transmission of a microsporidian sex ratio distorter inGammarus duebeni
Authors: Dunn A. M. , Hatcher M. J. , Terry R. S. , Tofts C. 
Published: June 2009

SUMMARYVertically transmitted parasites are transmitted from generation to generation of hosts usually via the host's gametes. Owing to gamete size dimorphism, the major transmission route is transovarial and selection (on the parasite) favours strategies which increase the relative frequency of the transmitting (female) host sex. These strategies impose unusual selection pressures on the host, and coevolution between hosts and vertically transmitted parasites has been implicated in speciation, in the evolution of symbiosis, and in the evolution of novel systems of host reproduction and sex determination. We review the evolutionary implications of vertically transmitted parasites in arthropods before focusing on strategies of transmission of a parasitic sex ratio distorter inGammarus duebeni. The efficiency of parasite transmission to new hosts is a key factor underlying the relationship between vertically transmitted parasites and their hosts. Vertically transmitted parasites must overcome 2 bottlenecks in order to ensure successful infection of future host generations: first, transmission from adult to gamete; and secondly, transmission to the germ-line of the infected host. We investigate these 2 processes with regard to transovarial transmission by a microsporidian parasite inGammarus duebeni. Parasite transmission from adult to eggs is highly efficient, with 96% of eggs of infected mothers inheriting the infection, whereas transmission to germ-line within infected embryos is relatively inefficient (72%). We measure parasite distribution between cells of developing embryos, and use these distributions to infer possible mechanisms of parasite transmission to germ-line. Parasite distribution within the embryo is dependent on host cell lineage, and is not consistent with unbiased segregation between daughter cells. These results indicate that parasites segregate together at host cell division, and may reflect a strategy of differential segregation to the host germ-line. We consider alternative parasite strategies at the cell-level in terms of their evolutionary implications.
The effect of homogenates and excretory/secretory products ofNippostrongylus brasiliensisand of acetylcholinesterase on the amplitude and frequency of contraction of uninfected rat intestinein vitro
Authors: Foster N. , Dean E. J. , Lee D. L. 
Published: June 2009

SUMMARYWhole worm homogenates and excretory/secretory (E/S) products of adultNippostrongylus brasiliensissignificantly decreased the amplitude of contractions of segments of uninfected rat intestine maintained in an organ bath, with significantly larger volumes of E/S products being required to bring about a similar decrease to that caused by the whole worm homogenate. Boiled samples of homogenate and E/S products significantly decreased the amplitude of contractions of uninfected rat intestine, but larger volumes were needed than with unboiled samples. Frequency of contraction was unaltered by homogenates or E/S products. When electric eel AChE was injected into the lumen of segments of uninfected rat intestine maintained in an organ bath there was no significant decrease in the amplitude of contractions. These results suggest that substances present in the E/S products ofN. brasiliensissignificantly reduce the amplitude of contractions of uninfected rat intestinein vitroand that the biochemical holdfast responsible for this phenomenon may not be AChE.
Isolation and characterization of a species-specific multicopy DNA sequence fromEntamoeba histolytica
Authors: Mittal V. , Bhattacharya A. , Bhattacharya S. 
Published: June 2009

SUMMARYA genomic library ofEntamoeba histolytica(pathogenic strain HM-1: IMSS) was screened to detect repetitive DNA clones other than those from the highly abundant ribosomal DNA (rDNA). One such clone (HMc) had a 2·3 kb insert which hybridized with the main genome and not the rDNA circle. Southern hybridization ofE. histolyticagenomic DNA, digested withEcoRI and probed with HMc, showed multiple bands. The banding pattern was identical in all axenic pathogenic strains tested. Differences, however, existed when the banding pattern of a pathogenic strain was compared with that of a non-pathogenic strain. HMc was present in about 25–30 copies per genome in strain HM-1: IMSS. Nucleotide sequence analysis of HMc revealed a partial open reading frame which hybridized with a 1·35 kb poly A+transcript in Northern blots. The deduced amino acid sequence did not, however, show significant homology with known proteins. The HMc sequence was found only inE. histolyticaas it hybridized with 5 different axenic strains ofE. histolyticabut did not recognize other closely related species ofEntamoeba. It has thus the potential to be used as a species-specific DNA probe.
Immunocytochemical study on biologically active neurosubstances in daughter sporocysts and cercariae of Trichobilharzia ocellata and Schistosoma mansoni
Authors: Solis-soto J. M. , De Jong Brink M. 
Published: June 2009

SUMMARYImmunocytochemical techniques applied to sections and whole-mount preparations of cercariae from two species of trematodes, Trichobilharzia ocellata and Schistosoma mansoni, revealed the occurrence of immunoreactivity (IR) to several neurosubstances in the nervous system (NS). Immunostaining was localized in cerebral ganglia, in the main commissure, in anterior and posterior nerve trunks, as well as in a pair of nerve fibres running along the tail. In T. Ocellata, immunoreactivity (IR) was observed with antisera raised against: glutamate, FMRFamide, catch-relaxing peptide (CARP), small cardiac peptide B (SCPB), arg-vasotocin (AVT), arg-vasopressin (AVP), and substance P. In S. mansoni antisera raised against glutamate, FMRFamide, CARP, SCPB, α-caudodorsal cell peptides (α-CDCP), and cholecystokinin (CCK) showed neuronal IR. With the other 51 antisera tested no IR was observed. With anti-APGWamide, IR was observed outside the NS in cells of the wall of the daughter sporocyst and in flame cells of cercariae of T. ocellata. IR to FMRFamide was present in the escape glands of the intrasporocystic cercariae of T. ocellata and S. mansoni. IR to somatostatin was observed in subtegumental parenchymal cells of cercariae of S. mansoni. IR to met-enkephalin was present in cells of the cercarial embryos and in undifferentiated cells in developing cercariae. Trematodes are, together with cestodes, phylogenetically the oldest classes in which glutamate-like material and immunopositivity to a number of neuropeptides isolated from invertebrates has been demonstrated. The results are discussed in relation to immunocytochemical data obtained for other platyhelminths, to endogenous functions of the immunopositive materials, and to their possible role in parasite–host interactions.
Detection of trypanosome infections in the saliva of tsetse flies and buffy-coat samples from antigenaemic but aparasitaemic cattle
Authors: Majiwa P. A. O. , Thatthi R. , Moloo S. K. , Nyeko J. H. P. , Otieno L. H. , Maloo S. 
Published: June 2009

SUMMARYRelatively simple protocols employing non-radioactive DNA probes have been used for the detection of African trypanosomes in the blood of mammalian hosts and the saliva of live tsetse flies. In combination with the polymerase chain reaction (PCR), the protocols revealed trypanosomes in buffy-coat samples from antigenaemic but aparasitaemic cattle and in the saliva of live, infected tsetse flies. Furthermore, the protocols were used to demonstrate concurrent natural infections of single tsetse flies with different species of African trypanosomes.
Detection of density-dependent growth and fecundity of helminths in natural infections
Authors: Shostak A. W. , Scott M. E. 
Published: June 2009

SUMMARYDensity-dependent constraints on parasite growth, survival or reproduction are thought to be important in preventing the unchecked increase in parasite numbers within individual hosts or host populations. While it is important to know where, and with what severity, density dependence is acting within the parasite life-cycle, interpretation of data from natural infections is difficult. In this paper, we present a Monte Carlo simulation technique for examining such data for evidence of density dependence. We also describe how this technique may be used to distinguish among mechanisms hypothesized to generate density-dependent phenomena.