摘要:

ABSTRACT.The mitochondrion appears to be essential for the growth of asexual, intraerythrocytic stages ofPlasmodium falciparumand may thus be a suitable chemotherapeutic target. The in vitro activity of almitrine, a mitochondrial ATP synthetase inhibitor used for the treatment of hypoxemia, was compared with other mitochondrial inhibitors against chloroquine‐susceptible and chloroquine‐resistantP. falciparumusing an isotopic semimicro drug susceptibility assay. The 50% inhibitory concentration (IC50) values of almitrine (range: 2.6–19.8 μM) were within similar range of values of other mitochondrial ATP synthetase inhibitors and doxycycline, a mitochondrial protein synthesis inhibitor. Almitrine was equally active against chloroquine‐susceptible and chloroquine‐resistant parasites. Drug combination studies showed no interaction between chloroquine and almitrine. Our results suggest that almitrine, a clinically safe drug, may represent a lead compound with a specific target against the mitochondrial ATP synthetase which may be useful for antimalarial ch

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb01493.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT.Cross‐transmission experiments were performed in order to determine the host specificity in the intermediate and definitive hosts of the four described dihomoxenousSarcocystisspecies,S. gallotiae, S. stehlinii, S. simonyi, andS. dugesiifrom lacertid lizards of the generaGallotiaandPodarcisfrom the Macaronesian Islands. Sarcocysts of either species from experimentally infected lizards were fed to a variety of laboratory‐bred lizard species of the generaGallotia, Lacerta, andPodarcis. These sarcocysts proved to be infectious to all examined animals, showing no definitive host specificity in the tested genera. Lizards of the generaChalcidesandTarentola, however, were not susceptible definitive hosts forS. gallotiae. The inoculation of experimentally obtained sporocysts of each of the fourSarcocystisspecies to various lacertid lizard species revealed varying degrees of intermediate host specificity, generally demonstrating each native host to be the most suscepti

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb01494.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT.Twenty‐five in vitro cultures ofGiardia duodenalisderived from a Brisbane patient were established to assess the genetic heterogeneity of a population. Each of the established lines carried a predominance of one of two distinct varieties ofGiardia. The two varieties were heterogeneous by four unambiguous criteria that were representative of the whole genome. These included restriction enzyme polymorphisms, hybridization with the cloned rDNA repeat and with a gene encoding a cysteine‐rich surface protein, electrophoretic karyotyping and DNA fingerprinting. Differences between parasites derived from this patient were greater than have been seen between all other establishedG. duodenalisin vitro cultures from both human and animals. The culture were heavily selected such that a singleGiardialine carried a predominance of one genotype and was not representative of the entire original populat

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb01495.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT.Cells of the ciliateTetrahymena thermophilafailed to establish cultures in lipid‐free standard synthetic nutrient medium if the initial population density was 250 cells per ml or less. These cells died within 10 h, but were saved and formed dense cultures if their medium was supplemented with 10 μg per ml of either certain phospholipids, 1,2‐di‐, 1‐monoglycerides, fatty acids, long‐chain alcohols, or sterols. Cell multiplication was followed in cultures in which the standard synthetic medium was supplemented with a selection of the compounds listed above. It was observed that the cells in the supplemented cultures in their exponential phases of growth had about the same average doubling times as control cells starting multiplication at 10‐fold higher initial cell densities in lipid‐free medium. These cells have been grown for decades in lipid‐free synthetic nutrient media at short (ca. two‐three h) doubling times. Therefore lipids have been considered nutritionally non‐essential for growth and multiplication of these cells. We propose that those compounds that rescue the cells at low cell densities act as “proliferation signals,”sensu lato. This effect of lipids and long‐chain alcohols has

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb01496.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT.The expression of cysteine proteinases by metacyclic promastigotes ofLeishmania mexicanawas investigated using gelatin polyacrylamide gel electrophoresis. Two prominent bands were detected which distinguished metacyclics from multiplicative promastigotes, lacking detectable cysteine proteinase activity, and amastigotes, with a distinct banding pattern composed of multiple enzymes. A correlation between relative activity of the metacyclic‐specific bands and the prevalence of metacyclics was found both during the growth cycle in vitro as metacyclogenesis occurred, and by comparison of stationary phase populations from consecutive subpassages in vitro. Irreversible inhibition of the metacyclic activities using N‐benzyloxycarbonyl‐phenylalanyl‐alanyl diazomethane did not inhibit metacyclic to amastigote transformation in vitro. These activities provide a useful biochemical marker for the metacyclic promastigotes ofL. m

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb01497.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT.The microsporidian speciesEnterocytozoon bieneusi, Septata intestinalisandAmeson michaeliswere compared by using sequence data of their rRNA gene segments, which were amplified by polymerized chain reaction and directly sequenced. The forward primer 530f (5′‐GTGCCATCCAGCCGCGG‐3′) was in the small subunit rRNA (SSU‐rRNA) and the reverse primer 580r (5′‐GGTCCGTGTTTCAAGACGG‐3′) was in the large subunit rRNA (LSU‐rRNA). We have utilized these sequence data, the published data onEncephalitozoon cuniculiandEncephalitozoon hellemand our cloned SSU‐rRNA genes fromE. bieneusiandS. intestinalisto develop a phylogenetic tree for the microsporidia involved in human infection. The higher sequence similarities demonstrated betweenS. intestinalisandE. cuniculisupport the placement ofS. intestinalisin the family Encephalitozoonidae. This method of polymerized chain reaction rRNA phylogeny allows the establishment of phylogenetic relationships on limiting material where culture and electron microscopy are difficult or impossible and can be applied to archival material to expand the molecular phylogenetic analysis of the phylum Microspora. In addition, the highly variable region(E. colinumbering 590–650) and intergenic spacer regions in the microsporidia were noted to have structural correspondence, suggesting the possibility t

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb01498.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT.Spore suspensions of microsporidian parasites of fish(Microsporidium ovoideum, Glugea stephani, Glugea atherinaeandSpraguea lophii) have been analyzed by flow cytometry. Spore nuclei were dyed either by propidium iodide or bis‐benzimide (Hoechst 33342). By observation of forward light scatter and fluorescence the four species could be distinguished and the mono‐ and diplokaryotic populations ofS. lophiiidentified. Staining of DNA by bis‐benzimide was better and easier than propidium iodide. Forward light scatter and fluorescence values were characteristic of each species and remained unchanged throughout the year, so flow cytometry can be used for distinction of spores of some microsporidian parasites once their flow cytometric parameters are known. However, special care has to be taken in tool calibration and material preparation for analysis because of the high precision of the tech

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb01499.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT.Ultrastructural studies onEimeria(syn.Epieimeria)anguillae(Apicomplexa), parasite of the digestive tract of the eel, have shown that the development of this parasite takes place completely within the host cell. Merogony and gamogony are intracellular but in the epicytoplasmic position. Sporogony is also located within the epithelial cells, which agrees with assignment of this coccidian in the family Eimeriidae. However, depending on the intensity of infection and the physiopathological reaction of the host, the gamont may behave in two ways. 1) In massive infections, gamogony stages cause a genuine destruction of intestinal epithelium. Large numbers of gamonts form nodules and parts of the seriously destroyed epithelium peel off and are released into the lumen of the gut and quickly discharged into the outer environment. This discharged epithelium envelops cells containing immature oocysts that then sporulate outside the host. 2) In light infections, the host cells, which are necrotic due to the presence of a zygote, are pushed between the surrounding intact cells towards the base of the epithelium. Closely above its basal lamella, the oocyst then undergoes sporulation. These results show no taxonomically important biological features (e.g. special mode of implantation to the host cell or active movement of the zygote). Because the morphological characteristics of Epieimeria do not differ significantly fromEimeria, we propose to suppress the genusEpieimeriaDyková and Lom, 1981, and relegate its species into the genusEimeria

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb01500.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT.The degree of strain and/or species diversity amongPneumocystis cariniiisolates is unknown. As a first approach to the study ofP. cariniigenetic relatedness, we compared the pulsed field gel electrophoretic karyotypes ofP. cariniiderived from lung homogenates of three immunosuppressed host animals: rats transtracheally inoculated withP. carinii‐infected rat lung; mice transtracheally inoculated withP. carinii‐infected mouse lung; and ferrets which developed reactivated latentP. cariniipneumonia. RatP. cariniipropagated on HEL299 cells was also examined. Karyotypes ofP. cariniiDNA from both rat lung homogenate and cell culture were identical (14 bands, 315–680 kb). In contrast, mouse and ferretP. cariniiDNA karyotypes were each distinctly different from the ratP. cariniisamples (mouseP. carinii15 bands, 315–610 kb; ferretP. cariniinine bands, 410–760 kb). Three distinct ratP. cariniigene probes reacted with both Southern‐transferred rat and mouseP. cariniiDNA but not with ferretP. cariniiDNA. Thus,P. cariniifrom rat, mouse, and ferret are genetically diverse. The results are consistent with recently reported antigenic and nucleic acid sequence differences amongP. cariniiisolates recovered from diff

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb01501.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACT.Leishmania donovanipromastigotes were collected, washed, resuspended in buffer, and assayed for sucrase activity. No activity was observed in the intact washed cells, but activity was measurable when the cells were permeabilized with Triton X‐100. Intracellular sucrase activity was highest in promastigotes grown at pH 7.4, somewhat lower in promastigotes grown at pH 5.5, and significantly lower in “amastigotes” grown at pH 5.5. No trehalase, lactase, or maltase activities were observed. Assay of the medium in which the cells had grown showed that most the sucrase activity was extracellular, i.e. was secreted into the medium during g

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb01502.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY