Publications

TitleAbstractYear
Filter
PMID
Filter
acanthamoeba royreba sp. n. from a human tumor cell culture.a new species of acanthamoeba was isolated from a culture of an established line of human choriocarcinoma cells. the identification of this strain, originally called the oak ridge strain, and the establishment of a new species for it were based on morphologic, serologic, and immunochemical studies. in general, the structure of the trophozoite did not differ significantly from that of other species of acanthamoeba, except that a body which more closely resembled a centriole than material describe ...1978566323
surface topography of acanthamoeba culbertsoni extracted from cerebrospinal fluid.an axenic culture of acanthamoeba culbertsoni, strain a-1, was obtained from the american type culture collection and injected, via the cisterna magna, into the subarachnoid space of dogs. attention was focused on the pleomorphic surface specialization of the pathogens suspended in cerebrospinal fluid and compared with those from trypticase soy broth suspensions. light and scanning electron microscopic comparisons of both inoculated and stock (control) specimens demonstrated similar surface feat ...1978744723
comparative studies on related free-living and pathogenic amebae with special reference to acanthamoeba.comparative studies were conducted on the structure, nutrition, protein composition, immunology, and effect on cell cultures of acanthamoeba sp. (lilly a-1 strain), a. castellanii (singh and neff strains), a. astronyxis, a. comandoni, a. polyphaga, a. terricola, hartmannella vermiformis, and naegleria gruberi. lilly a-1 strain of acanthamoeba received special attention owing to its pathogenicity for experimental animals. distinct differences were noted in structure, nutrition, and antigenic comp ...1975807717
pathogenic amoebas from brackish and ocean sediments, with a description of acanthamoeba hatchetti, n. sp.acanthamoeba culbertsoni was isolated from a sewage-spoil dump site near ambrose light, new york bight. a second species, acanthamoeba hatchetti, n. sp., was isolated from brewerton channel, baltimore harbor, maryland. both species killed laboratory mice after infection by the intranasal route.1977867031
differences in destruction of cysts of pathogenic and nonpathogenic naegleria and acanthamoeba by chlorine.the destructive action of chlorine on the pathogenic naegleria fowleri and acanthamoeba culbertsoni, the nonpathogenic n. gruberi, and an avirulent acanthamoeba isolate was investigated. n fowleri is somewhat more sensitive to chlorine than n. gruberi, whereas the two acanthamoeba strains are very resistant. this study yields information needed for the destruction of amoebic cysts in drinking water and swimming pools. it also gives some explanation for the occurence of acanthamoeba strains in th ...1976999278
ultrastructural changes of acanthamoeba culbertsoni in the brain of the experimentally infected white mouse. 19751227443
development of improved media for axenic cultivation of acanthamoeba culbertsoni, singh and das 1970.several varieties of peptone supported growth of a. culbertsoni to different extents reaching a maximum cell density of 1-2 x 10(6)/ml. proteose peptone and tryptone also yielded good growth when combined with thiamine and vitamin b12. a combination of proteose peptone with glucose, yeast extract and salts promoted excellent growth of a. culbertsoni with cell density reaching 1-2 x 10(7) cells/ml; tryptone and one of the indigenous peptones also yielded comparable growth when substituted for pro ...19892698860
sterols of acanthamoeba culbertsoni strain a-1.two new sterols, stigmasta-5,7,22,25-tetraene-3 beta -ol (1) and stigmasta-5,7,14,22,25-pentaene-3 beta -ol (2), have been characterized along with ergosterol and 7-dehydrostigmasterol in the nonsaponifiable fraction of the total lipids extracted from trophozoites of acanthamoeba culbertsoni strain a-1 (virulent strain). however, these sterols were found to be absent in the nonpathogenic strain c-7 of a. culbertsoni.19883242176
biochemical changes in mitochondria of mouse brain during experimental infection with acanthamoeba culbertsoni (strain-a-1). 19873440578
enzyme changes in virulent and avirulent strains of acanthamoeba culbertsoni during chlorophenoxyisobutyrate- or cholesterol-passage. 19873440579
elastase in the pathogenic free-living amoebae naegleria and acanthamoeba spp.the data showed that pathogenic free-living amoebae contain the proteolytic enzyme elastase. the levels of enzyme were similar in naegleria fowleri, n. australianis italica, and acanthamoeba culbertsoni a-1. no difference was found between elastase levels in a highly pathogenic n. fowleri and those in the same organism which had lost pathogenicity as a result of long-term axenic maintenance.19883182083
enzyme and chemical composition of plasma membranes of virulent and avirulent strains of acanthamoeba culbertsoni. 19863015776
acanthamoeba culbertsoni and naegleria fowleri: occurrence of antibodies in man.serum samples of 1,054 inhabitants of bohemia (czechoslovakia) were examined by means of indirect haemagglutination test with antigens from naegleria fowleri and acanthamoeba culbertsoni. with n. fowleri antigen the frequency of positive reactions did not exceed 3.5 per cent in lowest serum dilutions only. n. fowleri could not be identified as a possible causative agent in any chronic form of disease in man. significant accumulation of positive findings with a. culbertsoni antigen was observed i ...19892723426
effect of cholesterol and alpha-p-chlorophenoxyisobutyrate passage on virulence in acanthamoeba culbertsoni strain a-1 and c-7. 19863744661
effects of muramyl dipeptide and trehalose dimycolate on resistance of mice to toxoplasma gondii and acanthamoeba culbertsoni infections.the effects of synthetic muramyl dipeptide (mdp) and natural trehalose dimycolate (tdm) against parasitic infections by intracellular toxoplasma gondii and free-living acanthamoeba culbertsoni were studied. significant resistance against oral t. gondii infection was induced by intraperitoneal pretreatment with tdm but not with mdp. the protective effect of tdm against t. gondii was corroborated by a significant reduction in the number of cysts in brains of pretreated animals and elevated serum a ...19863759255
acanthamoeba culbertsoni and contact lens disinfection systems.acanthamoeba culbertsoni was used in this study inasmuch as its susceptibility to disinfection has not been examined. although heat was found to be the most effective means of disinfection some cysts survived this procedure. chlorhexidine exhibited a dose-response kill curve but the most effective concentrations are also corneo-toxic. polyaminopropylbiguanide (0.00005%) has good effectiveness against the cyst but was not completely cidal at the dose tested. thimerosal (0.002%) and hydrogen perox ...19892587034
purification and properties of phospholipase a2 of acanthamoeba culbertsoni. 19853879983
[cell-mediated immunity in experimental amoebic meningoencephalitis].cell-mediated and humoral immune reactions in mice infected with pathogenic acanthamoeba culbertsoni were observed according to the period of time after amoebic infection by intranasal inoculation. the degrees of blastogenesis of spleen cells induced by mitogens, which were measured using radioactive [3h]-thymidine, were compared between infected and non-infected control groups. the mitogens used in this blastogenesis experiment were concanavalin a (con a) and lipopolysaccharide(lps). on the oth ...19892486832
pathogenic free-living amoebae.studies on pathogenic free-living amoebae performed in korea were briefly reviewed. one strain of naegleria fowleri was isolated from the sewage, and 3 strains of acanthamoeba culbertsoni from a reservoir and the gill of fish. they were identified by morphological characteristics. three strains among the 4 were experimentally proved pathogenic to cause primary amoebic meningoencephalitis in mice. the virulence of n. fowleri depended upon various factors such as strain, weight and sex of mice, an ...19902133420
action of methylglyoxal bis (guanyl hydrazone) and related antiprotozoals on acanthamoeba culbertsoni.methylglyoxal bis(guanyl hydrazone) (mgbg) and the related diamidine compounds berenil and pentamidine inhibited multiplication of a. culbertsoni. the growth inhibition by mgbg (2.5 mm) in the peptone medium was accompanied by the disappearance of spermidine and a marked reduction in the level of diaminopropane. mgbg and berenil completely inhibited growth in a chemically defined medium at 1 mm and 1-2 microm concentration, respectively. however, there was no decrease in the polyamine levels in ...19902099334
encystment of acanthamoeba culbertsoni by organic effectors. 19836321338
[cell-mediated immunity in mice infected with acanthamoeba culbertsoni].observations were made on the differences of cell-mediated responses in mice of three infection groups differently scheduled in their severity with pathogenic acanthamoeba culbertsoni. infections were done by dropping 5 microliters saline suspension containing 3 x 10(3), 1 x 10(4), or 1 x 10(5) trophozoites, respectively. amoebae were cultured axenically in cgv medium and inoculated into the right nasal cavity of c3h/hej mice aging around 6-8 weeks, under the anesthesia by intraperitoneal inject ...19902095197
glutathione transferase activity in some flagellates and amoebae, and purification of the soluble glutathione transferases from acanthamoeba.glutathione transferase (gst) enzymes are toxicologically important from many points of view. nine protozoans were investigated here for their gst content. six aerobic amoebae had very different specific gst activities, but an anaerobic amoeba and two anaerobic flagellates did not have any gst activity, suggesting that the peroxidase activity of gst is an evolutionarily important property for aerobic organisms. the soluble gst isoenzymes of acanthamoeba culbertsoni and a. polyphaga were purified ...19902078188
immunization with killed acanthamoeba culbertsoni antigen and amoeba culture supernatant antigen in experimental acanthamoeba meningoencephalitis.mice immunized with killed (sonicated) acanthamoeba culbertsoni a-1 antigen displayed marked resistance to intranasal challenge with the amoeba. a primary immunization produced a survival rate of approximately 40%, and survival values of greater than 80% were obtained by multiple immunizations. similarly mice immunized with fluids from a-1 cultures were highly resistant to infection.19846464105
mitogenicity of naegleria fowleri extract for murine t lymphocytes.the whole-killed pathogenic free-living amoeba, naegleria fowleri, contained mitogenic activity (nfm) for mouse spleen cells. similar preparations from the non-pathogenic amoeba n. gruberi and the pathogenic acanthamoeba culbertsoni lacked mitogenic activity. fluids from n. fowleri cultures, containing amoeba antigens, also failed to cause proliferation of mouse spleen lymphocytes. spleen cells from athymic nude mice failed to respond to nfm. in addition, nylon wool non-adherent, but not the adh ...19846607875
encystment of acanthamoeba culbertsoni in non-nutrient inorganic media. 19836667999
organic nutrients & catabolite repression of encystation of acanthamoeba culbertsoni. 19836668001
characterization of l-glutamate dehydrogenase activity of axenically grown acanthamoeba culbertsoni. 19836671673
infection of the central nervous system due to acanthamoeba.it is well established that acanthamoeba castellanii, acanthamoeba culbertsoni, acanthamoeba polyphaga, and probably other species of free-living amebas are virulent opportunists capable of producing disease in humans and animals. human infections involving brain, eyes, skin, and lungs have been reported from all continents. central nervous system (cns) infection due to acanthamoeba species usually occurs in chronically ill, debilitated individuals, some of them receiving immunosuppressive thera ...19912047674
in vitro sensitivity of virulent acanthamoeba culbertsoni to a variety of drugs and antibiotics. 19846706465
spontaneous occurrence of antibodies against pathogenic amoebae of the limax group in domestic animals.sera of 1 218 animals were examined using indirect haemagglutination reaction with antigens of naegleria fowleri and acanthamoeba culbertsoni. rabbit sera (214 samples) gave negative reaction with both antigens. bovine sera (593 samples) reacted positively in 1.5%, particularly with the antigen of a. culbertsoni. out of the 411 pigs examined 12% were positive with one or both of the antigens. in one of the pig farms of a modern type the positivity with one or both of the antigens. in one of the ...19817239352
affinity chromatography technique for purification of glutamate dehydrogenase of axenically-grown acanthamoeba culbertsoni. 19817309086
effectivity of contact lens disinfection systems against acanthamoeba culbertsoni.thirteen commercially available contact lens solutions were tested for their ability to kill the cysts of acanthamoeba culbertsoni. miraflow, which contains 20% isopropyl alcohol, was the most effective at killing the cyst (94%), followed by solutions containing thimerosal (89%). the rigid gas permeable lens solutions in general were more effective than soft lens solutions. none of the solutions tested were completely cidal, but our data do suggest a combination of a good daily cleaner and disin ...19912027653
protective and curative effects of rifampicin in acanthamoeba meningitis of the mouse.balb/c mice inoculated nasally with acanthamoeba culbertsoni, resulting in amebic encephalitis and death 3-7 days, were treated with rifampicin prophylactically (daily for 2 days with 75 and 100 mg/kg) and after infection (daily for 5 days with doses of 10-100 mg/kg). prophylactic treatment resulted in full protection against infection, as assessed by absence of symptoms of central nervous system malfunction and negative brain culture 10 days after inoculation. curative treatment was effective a ...19912010646
action of dl-alpha-difluoromethyl ornithine on acanthamoeba culbertsoni.the multiplication of a. culbertsoni in the peptone medium was not inhibited by 10-20 mm concentration of alpha-difluoromethyl ornithine (dmfo) while a partial and transient inhibition of cell multiplication was observed by 10-20 mm dfmo in proteose peptone, yeast extract, glucose (pyg) medium. ornithine decarboxylase (odc) activity in the cells and cell free extracts was strongly inhibited by dfmo, excluding enzyme refractoriness and impermeability of cells for dfmo as the possible causes of df ...19911816099
isolation of acanthamoeba sp. from a greyhound with pneumonia and granulomatous amebic encephalitis.acanthamoeba were isolated from a naturally occurring animal infection of granulomatous amebic encephalitis. the amebas were grown from lung lesions from a 1-year-old greyhound puppy, which was 1 of several dogs in a kennel that was affected by a progressive fatal neurologic and respiratory disease. the centers for disease control, atlanta, georgia, confirmed the disease to be acanthamebiasis and specifically identified the amebas as acanthamoeba culbertsoni by fluorescent antibody testing on br ...19938373852
[natural killer cell activity in mice infected with acanthamoeba culbertsoni].the natural killer cell activity of splenocytes and tbc, active nk cells, recycling capacity of natural killer cells were observed by means of both the 51cr-release cytotoxicity assay and single cell cytotoxicity assay against yac-1. c3h/hej mice were infected intranasally with 1 x 10(4) or 1 x 10(5) trophozoites of pathogenic acanthamoeba culbertsoni. the infected mice showed mortality rate of 34% in 1 x 10(4) group and 65% in 1 x 10(5) group, and mean survival time was 16.40 +/- 3.50 and 13.20 ...19921627498
polyamine oxidase from acanthamoeba culbertsoni specific for n8-acetylspermidine.polyamine oxidase plays a key role in the catabolism of polyamines and regeneration of spermidine and putrescine. the mammalian enzyme utilises n1-acetylspermidine, and n8-acetylspermidine, although formed in the mammals, is not catabolised further. we have characterised an enzyme from acanthamoeba culbertsoni which acts preferentially on n8-acetylspermidine. the highly unstable enzyme was stabilised in the presence of glycerol or dimethylsulphoxide together with spermine and purified 400-fold b ...19921565141
experimental infections with pathogenic free-living amebae in laboratory primate hosts: i. (b) a study on susceptibility to acanthamoeba culbertsoni.susceptibility to a. culbertsoni was studied in 15 old world monkeys by intranasal, intravenous, or intrathecal inoculation of trophozoites. no clinically detectable disease resulted from either intranasal or intravenous inoculation, but 4 of 7 monkeys inoculated intrathecally succumbed to acutely fatal meningoencephalitis. virulence of the ameba varied with cultural age of the inoculum. size of inoculum, passages through animal tissues, and host-immune competence were other factors of considera ...19751165552
identification of the polyamine n8-acetyltransferase involved in the pathway of 1,3-diaminopropane production in acanthamoeba culbertsoni.a cytosolic polyamine n-acetyltransferase that preferentially catalyzes the acetylation of spermidine in the n8-position was identified in the free-living pathogenic amoeba acanthamoeba culbertsoni. in addition to spermidine, the enzyme also catalyzed the acetylation of spermine and putrescine with michaelis constants (km values) of 97, 12, and 10 microm, respectively. the km value for acetylcoenzyme a (acetyl-coa) was estimated to be 11 microm, whereas coa had an inhibitory constant of 6 microm ...19968801564
scanning electron microscopy of acanthamoeba culbertsoni as observed in the subarachnoid space.scanning electron microscopy was used to study the pathogenic protozoan, acanthamoeba culbertsoni, in the leptomeningeal subarachnoid space surrounding the spinal cord of the experimentally inoculated dog. know to inhabit such areas as moist soils, stagnant waters, and sewage around the world, these protozoans have been identified as etiologic agents in numerous cases of meningoencephalitis. infection occurs via a nasopharyngeal inoculation, through penetration of the olfactory mucosal epitheliu ...1977906979
meningoencephalitis due to acanthamoeba sp. pathogenesis and clinico-pathological study.amebic meningoencephalitis (am) and primary amebic meningoencephalitis (pam) are infectious diseases essentially confined to the central nervous system (cns) and caused by free-living amebas of the genus acanthamoeba (a.) and naegleria (n.) respectively. am due to a. sp. (acanthamoeba castellanii and acanthamoeba culbertsoni) have been reported in chronically ill debilitated individuals, some of them under immunosuppressive therapy, or in immunologically impaired patients without a history of re ...1977857580
the interaction of acanthamoeba spp. with activated macrophages and with macrophage cell lines.acanthamoeba spp. are free-living amebae associated with amebic keratitis and chronic granulomatous amebic encephalitis. the present studies were undertaken to compare the pathogenicity of three species of acanthamoeba in b6c3f1 mice after intranasal challenge with acanthamoeba-induced cytopathogenicity for different macrophage populations. the ability of murine macrophage cell lines and activated murine peritoneal macrophages to lyse acanthamoeba has been assessed by coincubating macrophages wi ...19989703682
quantation by flow microfluorometry of total cellular dna in acanthamoeba.the dna content of five species of acanthamoeba was determined by flow microfluorometry. acanthamoeba castellanii (ac-30), acanthamoeba polyphaga (apg and p-23), acanthamoeba rhysodes, acanthamoeba culbertsoni (a-1), and acanthamoeba royreba were grown in a casitone based medium 24-48 hr. the trophozoites were harvested, and evaluated for dna-bound fluorescence. all species tested has dna values between 2.0-5.0 pg/cell. these results placed dna/cell values of acanthamoeba slightly lower than dna ...1978361883
maintenance of acanthamoeba culbertsoni by cryopreservation.in order to determine the viability of trophozoites of acanthamoeba culbertsoni under cryopreservation conditions, cultures in serum-casein-glucose-yeast extract medium were subject to 5%, 7.5%, and 10% concentrations of dimethylsulfoxide (dmso). with the methodology followed, the percentages of recovery varied between 75.6% and 86.6% with dmso at 10%, between 54.5% and 73.5% with dmso at 7.5%, and between 43.6% and 68.5% with dmso at 5%. the amebae were kept in liquid nitrogen for 30-210 days. ...19989920325
retrospective identification of acanthamoeba culbertsoni in a case of amoebic meningoencephalitis.acanthamoeba culbertsoni was identified retrospectively in a case of amoebic meningoencephalitis, previously reported by jager and stamm (lancet, 2, 1343, 1972). this is the second report of this species causing secondary infection in man. positive results were obtained only with anti-a. culbertsoni sera when the brain sections were stained by the indirect immunofluorescence antibody test with various antisera produced against different acanthamoeba species. antiserum raised against purified pla ...1978357454
the effects of some factors on the growth and morphology of naegleria sp. and three strains of the genus acanthamoeba.the effects of various biophysical and chemical factors on the cytology of vegetative stages of naegleria sp., vitek strain, acanthamoeba culbertsoni, acanthamoeba castellanii, neff strain and acanthamoeba polyphaga, no. 1289, were studied. the amoebae were cultured in a liquid medium under axenic conditions. the optimum temperature was 37 degrees c for pathogenic strains of naegleria sp. and acanthamoeba culbertsoni and 20 degrees c for a. castellanii. no changes were observed in the growth of ...19754366
changes in the lipid composition and activities of isocitrate dehydrogenase and isocitrate lyase during encystation of acanthamoeba culbertsoni strain a-1.the contents of total lipids, total sterols, total and individual phospholipids: lysophosphatidyl choline, lysophosphatidyl ethanolamine, phosphatidyl choline, phosphatidyl ethanolamine and alkali-stable phospholipids i and ii, were significantly lower in mature cysts of acanthamoeba culbertsoni strain a-1 than in trophozoites. the major constituent sterols of trophozoites, viz. ergosterol, 7-dehydrostigmasterol and 7,22,25-tridehydrostigmasterol which resolved as a single spot on thin-layer chr ...19873445347
immunity to acanthamoeba culbertsoni: experimental studies with acanthamoeba and control antigen preparations.mice were intranasally immunized with living and killed acanthamoeba as well as culture supernatant, living toxoplasma and bcg, and challenged with pathogenic a. culbertsoni strain a-1. the best protection was achieved with killed amoebae of the same strain. a high rate of mortality was observed in immunized mice treated with immunosuppressives and challenged with a. culbertsoni a-1. the significance of the results in relation to environmental human infection is discussed.19873449996
polyamine metabolism as a target for growth inhibition of acanthamoeba culbertsoni.alpha-difluoromethylornithine had no inhibitory effect on the growth of acanthamoeba culbertsoni, while methylglyoxal bis(guanyl-hydrazone) and sinefungin completely blocked amebic growth at 2.5 mm and 5 micrograms/ml concentrations, respectively. cyclohexylamine caused only partial inhibition of amebic growth at 50-200 microm concentrations. methylglyoxal bis(guanyl-hydrazone) inhibited s-adenosylmethionine decarboxylase of a. culbertsoni indicating this enzyme to be the target for its antiameb ...19873120609
putrescine-activated s-adenosylmethionine decarboxylase from acanthamoeba culbertsoni.acanthamoeba culbertsoni, the free living pathogenic amoeba responsible for fatal meningoencephalitis, contains an s-adenosylmethionine decarboxylase (ec 4.1.1.50) which is strongly activated by putrescine and to a lesser extent by cadaverine; spermidine, spermine, diaminopropane and 1,6-diaminohexane are inactive. methylglyoxal bis-(guanylhydrazone) competitively inhibited the enzyme with a ki value of 123 microm. the enzyme was strongly inhibited by berenil (ki = 0.5 microm) and to a lesser ex ...19873600699
cytopathic changes in rat microglial cells induced by pathogenic acanthamoeba culbertsoni: morphology and cytokine release.to determine whether pathogenic acanthamoeba culbertsoni trophozoites and lysate can induce cytopathic changes in primary-culture microglial cells, morphological changes were observed by transmission electron microscopy (tem). in addition, the secretion of two kinds of cytokines, tumor necrosis factor alpha (tnf-alpha) and interleukin-1beta (il-1beta), from microglial cells was observed. trophozoites of pathogenic a. culbertsoni made contact with microglial cells and produced digipodia. tem reve ...200111427438
amoebae isolated from the atmosphere of mexico city and environs.a protozoological analysis was performed from june to august, 1982 to isolate small free-living amoebae from the atmosphere by using an air vacuum sampler and several filters. monoxenic medium (nonnutritive agar plus escherichia coli) and axenic medium (de jonckheere, 1977) were used to culture the isolates. the species isolated included naegleria sp. alexeieff emend. calkins, acanthamoeba polyphaga puschkarew, vahlkampfia jugosa page, acanthamoeba astronyxis ray and hayes, acanthamoeba castella ...19873803333
conditioned medium from stimulated mononuclear leukocytes augments human neutrophil-mediated killing of a virulent acanthamoeba sp.human neutrophils in the presence of serum containing anti-amoeba antibody either lacked amoebicidal activity or were poorly amoebicidal for acanthamoeba culbertsoni. in contrast, neutrophils preexposed for 1 h to supernatants from human peripheral blood mononuclear leukocytes (mnls) stimulated with phytohemagglutinin demonstrated significant amoeba killing in the presence of serum containing anti-acanthamoeba antibodies. supernatant from mnl cultured in the absence of phytohemagglutinin were no ...19863943902
isolation of acanthamoeba culbertsoni from a patient with meningitis.a case of amoebic meningitis, presumably primary, was encountered in the christian medical college hospital, vellore, south india, in november 1983. the patient, a 40-year-old man, had cerebrospinal fluid rhinorrhea before the meningitis developed. acanthamoeba culbertsoni was repeatedly demonstrated in and cultured from the cerebrospinal fluid. the patient responded dramatically to a combination therapy of penicillin and chloramphenicol.19853988911
rapid visualization of acanthamoeba using fluorescein-conjugated lectins.we investigated the efficacy of fluorescein-conjugated lectins (fcls) for the rapid visualization of acanthamoeba species. cultures of acanthamoeba castellani, acanthamoeba culbertsoni, and acanthamoeba polyphaga were established on nonnutrient agar plates supplemented with escherichia coli. maximal trophozoite populations were established four to five days after initial subculturing; mature cysts were routinely noted three to six days later. at various time points, trophozoites and/or cysts wer ...19882458096
nutritional studies on acanthamoeba culbertsoni and development of chemically defined medium.a chemically defined medium containing 11 amino acids, 3 vitamins, 6 inorganic salts and glucose, yielding maximum cell densities of 1.5-2.5 x 10(7) cells/ml, has been developed for acanthamoeba culbertsoni with a mean generation time (mgt) of 10 h. a medium containing six amino acids viz. arginine, methionine, leucine, isoleucine, valine and glycine along with other components could also support good albeit slower growth (mgt 27 h) of the amoeba. acetate did not serve as a suitable carbon/energ ...19902359051
[effects of hydrostatic pressure per se and of inert gases on a limax-type free-living amoeba: acanthamoeba culbertsoni].the authors investigated the high hydrostatic and gas (nitrogen and helium) pressure effects on the morphology, missing encysting process and mortality rate of acanthamoeba culbertsoni trophozoïtes. these studies have been performed by the means of scanning electron microscopy (sem). it has been possible to show that the modulus of dissolving of both gas in water and oil is insufficient to explain the very important volumetric changes. thereafter it appears that there is clathrate compounds form ...19836304598
in vitro shock response to different stressors in free living and pathogenic acanthamoeba.three stresses, viz heat, oxidative and ph shocks, were applied to cultures of three species of acanthamoeba, free-living acanthamoeba rhysodes and pathogenic acanthamoeba castellanii and acanthamoeba culbertsoni. the effect of each stressor on trophozoite integrity was evaluated by the amount of heat shock protein (hsp)60 and hsp70 produced and by exclusion of 0.2% congo red. hsp60 and hsp70 levels were estimated using western blotting and subsequent densitometric analyses. unstimulated trophoz ...200010899527
pathogenic and free-living protozoa cultured from the nasopharyngeal and oral regions of dental patients.protozoa of nose, mouth, and pharynx of 30 randomly chosen female caries patients at an odontological clinic of the national autonomous university of mexico, were surveyed by culture from swabs. culture tubes of swabs from each patient were observed every other day during 5 weeks. pathogenic protozoa found included entamoeba histolytica schaudinn, 1903; naegleria fowleri carter, 1970; acanthamoeba castelanii douglas, 1930; acanthamoeba culbertsoni singh & das, 1970; and balantidium coli (malmste ...19846370674
activation of the alternative pathway of complement by acanthamoeba culbertsoni.normal human serum (nhs) contained an amoebicidal property for acanthamoeba culbertsoni. killing was quantitated by measuring the ability of the amoebae to undergo cell division subsequent to exposure to nhs, and also by microscopical examination. plasma membrane disruption and extrusion of intracellular components occurred within 5-10 min following exposure to nhs. adsorption of specific antibody did not remove the amoebicidal activity while heating serum at 56 degrees c/30 min or treatment wit ...19836418422
antigens of selected acanthamoeba species detected with monoclonal antibodies.acanthamoeba species are ubiquitous soil and freshwater protozoa that have been associated with infections of the human brain, skin, lungs and eyes. our aim was to develop specific antibodies to aid in rapid and specific diagnosis of clinically important isolates. mice were variously immunised with live mixtures of acanthamoeba castellanii strain 112 (ac112) trophozoites and cysts, or with sonicated, formalin-fixed or heat-treated trophozoites, or with a trophozoite membrane preparation. eight h ...200515964573
identification of differentially expressed cdnas in acanthamoeba culbertsoni after mouse brain passage.free-living amoebae of the genus acanthamoeba are causative agents of granulomatous amebic encephalitis and amebic keratitis. because the virulence of acanthamoeba culbertsoni cultured in the laboratory is restored by consecutive brain passages, we examined the genes induced in mouse brain-passaged a. culbertsoni by differential display reverse transcriptase polymerase chain reaction (ddrt-pcr). enhanced a. culbertsoni virulence was observed during the second mouse brain passage, i.e., infected ...200616514277
phenothiazine compounds inhibit in vitro growth of pathogenic free-living amoebae.the phenothiazine compounds trifluoperazine dihydrochloride and chlorpromazine hydrochloride have in vitro activity against the pathogenic free-living amoebae naegleria fowleri, acanthamoeba culbertsoni, and acanthamoeba polyphaga. drug concentrations of 10 microm were amoebastatic; concentrations of 50 microm were either amoebastatic or amoebicidal. concentrations of 100 microm were generally amoebicidal. the mechanism of drug action is unclear. it may reflect sensitivity of amoeba calcium regu ...19846703673
[the effect of silica on the development of experimental acanthamoeba meningoencephalitis with reference to the macrophage role in mice].the role of macrophages was observed in intranasally infected c3h/hej mice with trophozoites (3 x 10(5)) of acanthamoeba culbertsoni which was a kind of free-living amoebae inducing meningoencephalitis in human and experimental animals. the mortality was 60% in the group of intraperitoneally injected mice with silica (0.5 mg/0.5 ml). it was much higher than that of 10% in the group of amoeba infected mice without silica administration. the phagocytic index of peritoneal macrophages co-cultured w ...19947834243
[natural killer cell activity in mice infected with free-living amoeba with reference to their pathogenicity].the purpose of this observation was to investigate the natural killer cell activities in mice infected with pathogenic free-living amoeba, naegleria fowleri and acanthamoeba culbertsoni according to the infection doses, and infected with non-pathogenic free-living amoeba, naegleria gruberi. the natural killer cell activity was examined by means of target binding capacity, active nk cell and maximum recycling capacity of the mice after inoculating free-living amoebae with low and high doses. the ...19938241083
infections caused by pathogenic free-living amebas (balamuthia mandrillaris and acanthamoeba sp.) in horses.this article describes amebic infections in 4 horses: granulomatous amebic encephalitis caused by balamuthia mandrillaris and acanthamoeba culbertsoni and systemic infections caused by acanthamoeba sp. the former infection occurred in 1 of 4 horses spontaneously without any underlying conditions; the latter amebic infection was perhaps "opportunistic" considering the visceral involvement by this protozoan in association with aspergillus sp. and/or escherichia coli and pseudomonas sp. the clinico ...200717459867
[the effect of active immunization with acanthamoeba culbertsoni in mice born to immune mother].acanthamoeba culbertsoni is a pathogenic free-living amoeba causing primary amoebic meningoencephalitis (pame) in human and mouse. several reports on the immune responses in mice with this amoebic infection have been published, but the effects of transferred passive immunity on the active immunization in offspring mice have not been demonstrated. this experiment was done to observe the effect of active immunization with acanthamoeba culbertsoni in mice born to immune mothers. acanthamoeba culber ...19938343458
identification of antigens of pathogenic free-living amoebae by protein immunoblotting with rabbit immune and human sera.prominent antigens of pathogenic and nonpathogenic free-living amoebae were identified by using polyclonal rabbit immune sera in immunoblot assays. the intent was to determine if prominent epitopes identified with rabbit immune sera could also be recognized by human sera. with rabbit sera, the development of immunoreactive bands was restricted to molecular masses of greater than 18.5 kda for naegleria, hartmannella, and vahlkampfia antigens. two or more broad bands of less than 18.5 kda were pro ...19948556491
in vitro destruction of nerve cell cultures by acanthamoeba spp.: a transmission and scanning electron microscopy study.trophozoites of 4 species of acanthamoeba were cytopathic for cultured rat b103 neuroblastoma cells. cytopathogenicity was evaluated by a chromium release assay and by transmission and scanning electron microscopy. acanthamoeba culbertsoni, acanthamoeba castellanii, and acanthamoeba polyphaga destroyed b103 target cells at 37 c as evidenced by the release of radiolabel. acanthamoeba astronyxis did not produce cytopathology at 37 c but destroyed nerve cells at 25 c. transmission and scanning elec ...19968885887
the possibility of congenital infection with acanthamoeba culbertsoni.acanthamoeba culbertsoni is one of the free-living amoebae which are known to be pathogenic to man, causing granulomatous amoebic encephalitis (gae). in this study, acanthamoeba culbertsoni was isolated from a water sample of el-mahmoudia canal in alexandria, in july-1993. this was used to infect mice intranasally to study the histopathological picture of the brain and lungs. the neuropathological features consisted of chronic granulomatous encephalitis in which cysts and trophozoites were found ...19968918032
acanthamoeba meningoencephalitis following autologous peripheral stem cell transplantation.amoebic meningoencephalitis is an unusual complication of bone marrow transplantation. we report a case of acanthamoeba meningoencephalitis in a patient with non-hodgkin's lymphoma after autologous stem cell transplantation. leg weakness, fever and urinary retention developed 69 days following transplantation. the patient then developed fever, generalized tonic clonic seizure, rapid deterioration of mental functions and hypercapneic respiratory failure. magnetic resonance imaging demonstrated a ...19989720747
cloning of a cysteine proteinase gene from acanthamoeba culbertsoni.free living amoeba, including pathogenic acanthamoeba culbertsoni, are widely distributed in soil and fresh water. it has been found that cysteine proteinases are more active in pathogenic strains of amoeba whereas serine proteinases are found in both pathogenic and nonpathogenic strains. cysteine proteinases thus play important roles in the pathogenesis of several parasitic infections and have been proposed as targets for the structure-based strategy of drug design. as the first step toward app ...199910597037
upregulated expression of the cdna fragment possibly related to the virulence of acanthamoeba culbertsoni.identification of the genes responsible for the recovery of virulence in brain-passaged acanthamoeba culbertsoni was attempted via mrna differential display-polymerase chain reaction (mrna dd-pcr) analysis. in order to identify the regulatory changes in transcription of the virulence related genes by the brain passages, mrna dd-pcr was performed which enabled the display of differentially transcribed mrnas after the brain passages. through mrna dd-pcr analysis. 96 brain-passaged amoeba specific ...199910634042
apoptosis of primary-culture rat microglial cells induced by pathogenic acanthamoeba spp.to determine whether trophozoites and lysates of pathogenic acanthamoeba spp. induce apoptosis in primary-culture microglial cells, transmission electron microscopic (tem) examinations, assessment of dna fragmentation by agarose gel electrophoresis, and the tdt-mediated dutp nick-end labeling assay were performed. when a trophozoite of pathogenic acanthamoeba culbertsoni came in contact with a microglial cell, the digipodium was observed by tem. nuclear chromatin condensation was observed in 10% ...200010799471
pathologic quiz case. progressive fatal encephalopathy in an immunosuppressed patient with a history of discoid lupus erythematosus. subacute granulomatous meningoencephalitis (acanthamoeba culbertsoni). 200415335263
in vitro cytotoxicity of acanthamoeba spp. isolated from contact lens containers in korea by crystal violet staining and ldh release assay.in order to observe the cytotoxicity of acanthamoeba spp., which were isolated from contact lens containers as ethiological agents for the probable amoebic keratitis in korea, the crystal violet staining method and ldh release assay were carried out. in the crystal violet staining method, among eight contact lens container isolates, isolate 3 (acanthamoeba ka/ls5) showed 83.6% and 81.8% of cytotoxicity, and isolate 7 (acanthamoeba ka/ls37) showed 28.2% and 25.1% of cytotoxicity, in 1 mg/ml and 0 ...200010905072
standardized method of measuring acanthamoeba antibodies in sera from healthy human subjects.acanthamoeba species can cause serious, debilitating, and sometimes life-threatening infections. three groups have been identified using morphological and immunological comparisons. previous serological studies have utilized a variety of antigen preparations and assay methods and reported disparate (3 to 100%) results. this study was designed to (i) optimize an enzyme-linked immunosorbent assay for detecting serum antibodies to each of the acanthamoeba serogroups and (ii) test 55 healthy individ ...200111427418
is the intestinal tract a portal of entry for acanthamoeba infection?acanthamoeba culbertsoni isolated from a water sample of el-mahmoudia canal in alexandria, was orally inoculated into a mouse model (200-400 amoebae/mouse) under different conditions. one week postinfection (p.i.), 20% of infected normoacidic mice and all animals received cimetidine or tetracycline prior to infection passed the parasite in their stools. one month p.i., 70% of cimetidine and 100% of tetracycline pretreated mice showed marked erosion in the intestinal mucosa and areas of necrosis ...200111775104
predation of cryptosporidium oocysts by protozoa and rotifers: implications for water quality and public health.predation by free-living protozoa and rotifers was investigated as a possible mechanism for the removal of cryptosporidium parvum oocysts in aquatic ecosystems including wastewater treatment plants. free-living ciliated protozoa (stylonychia mytilus, paramecium caudatum and an unidentified wastewater wetland ciliate), an amoeba (acanthamoeba culbertsoni) and rotifers, all commonly found in aquatic ecosystems, were exposed to varying doses of c. parvum oocysts. all organisms investigated ingested ...200312639009
[a simple qualitative assay for intracellular growth of legionella pneumophila within acanthamoeba culbertsoni]. 200312806931
[a comparative study on hydrolase activities in acanthamoeba culbertsoni and a. royreba]specific or non-specific cytolytic processes of free-living amoebae causing meningoencephalitis have been emphasized and the cytolytic ability related to hydrolases in entamoeba sp. and naegleria sp. has also been reported since the latter half of 1970's. however, no information on hydrolase activities in acanthamoeba sp. is available. hydrolases in acanthamoeba culbertsoni, a pathogenic species of free-living amoebae, were assayed and compared with those in a non-pathogenic species, a. royreba. ...198812811054
[immunological tests by anti-free-living amoebas serum produced in experimental animals: ii. indirect fluorescent antibody titer of anti-free-living amoebas serum produced in rabbits]the indirect fluorescent antibody test was performed to demonstrate the antibody production in the rabbits immunized with free-living amoebas; acanthamoeba culbertsoni and naegleria fowleri, and antibody titer changes by immunization duration. rabbits were immunized with acanthamoeba culbertsoni and naegleria fowleri which were cultured axenically in cgvs medium. for experiments, rabbits were divided into two groups; small dose group received 10(4) intravenously with live or dead free-living amo ...197812902774
[immunological tests by anti-free-living amoebas serum produced in experimental animals: i. immobilization of free-living amoebas in vitro by rabbit antiserum]rabbits were immunized with free-living amoebas by intravenous injections. the amoebas were acanthamoeba culbertsoni and naegleria fowleri and obtained by axenic cultivation in cgvs medium. each rabbit received 10(6) of acanthamoeba culbertsoni and 10(5) of naegleria fowleri trophozoites respectively every other day in three doses and finally one booster dose at 1 week later. antiserum was collected from thc following day of the booster injection up to 2 months period, and stored at -30 degrees ...197812902782
legionella dumoffii djla, a member of the dnaj family, is required for intracellular growth.legionella dumoffii is one of the common causes of legionnaires' disease and is capable of replicating in macrophages. to understand the mechanism of survival within macrophages, transposon mutagenesis was employed to isolate the genes necessary for intracellular growth. we identified four defective mutants after screening 790 transposon insertion mutants. two transposon insertions were in genes homologous to icmb or dotc, within dot/icm loci, required for intracellular multiplication of l. pneu ...200415155669
differential stimulation of microglial pro-inflammatory cytokines by acanthamoeba culbertsoni versus acanthamoeba castellanii.acanthamoeba spp. are opportunistic pathogens that cause granulomatous amebic encephalitis. we compared the highly pathogenic species a. culbertsoni to the relatively less pathogenic species a. castellanii for its capacity to elicit from neonatal rat microglia the gene expression of pro-inflammatory cytokines. acanthamoeba culbertsoni elicited a robust cytokine gene response by neonatal rat microglia in vitro as compared to a. castellanii. the preponderant cytokine elicited at the mrna and prote ...200415352331
isolation and identification of mycobacteria from soils at an illegal dumping site and landfills in japan.in order to study the diversity and community of genus mycobacterium in polluted soils, we tried to isolate mycobacteria from 11 soil samples collected from an illegal dumping site and 3 landfills in japan. using culture methods with or without acanthamoeba culbertsoni, a total of 19 isolates of mycobacteria were obtained from 5 soil samples and 3 of them were isolated only by the co-culture method with the amoeba. conventional biochemical tests and sequencing of the hsp65, rpob, and 16s rrna ge ...200616858142
effect of caspofungin on trophozoites and cysts of three species of acanthamoeba.amoebic keratitis is difficult to treat, without total efficacy in some patients because of cysts that are less susceptible than trophozoites to the usual treatments. we investigated here the in vitro effectiveness of caspofungin, a new antifungal, against three species of acanthamoeba.200717079240
polyamine metabolism in acanthamoeba culbertsoni.1,3-diaminopropane has been identified as the major polyamine of acanthamoeba culbertsoni. n-acetylputrescine and spermidine were present in appreciable amounts and putrescine as well as n-acetylspermidine were also detected, but spermine was absent. changes in polyamine levels were observed during the growth of amoebae. ornithine decarboxylase activity was detected in cell-free extracts but there was very low activity of arginine and lysine decarboxylases. a potent polyamine oxidase was demonst ...19938441357
legionella impletisoli sp. nov. and legionella yabuuchiae sp. nov., isolated from soils contaminated with industrial wastes in japan.in this study, we tried to isolate legionellae from nine legionella dna-positive soil samples collected from four different sites contaminated with industrial wastes in japan. using culture methods with or without acanthamoeba culbertsoni, a total of 22 isolates of legionellae were obtained from five of the nine samples. identification of species and/or serogroups (sgs), performed by dna-dna hybridization and agglutination tests, revealed that the 22 isolates consisted of ten isolates of legione ...200717197147
acanthamoeba culbertsoni: analysis of amoebic adhesion and invasion on extracellular matrix components collagen i and laminin-1.acanthamoeba are free-living amoebae found in most environments that can cause brain and corneal infections. to infect humans, these pathogens must interact with host cells and the extracellular matrix (ecm). in order to define the mode by which amoebae recognize ecm components and process this recognition, we analyzed acanthamoeba culbertsoni attachment and invasion, respectively, on collagen i and laminin-1 and on tridimensional collagen i and matrigel matrices. we determined that amoebae surf ...201019698710
reevaluation of an acanthamoeba molecular diagnostic algorithm following an atypical case of amoebic keratitis.amoebic keratitis (ak) is a potentially blinding infection, the prompt diagnosis of which is essential for limiting ocular morbidity. we undertook a quality improvement initiative with respect to the molecular detection of acanthamoebae in our laboratory because of an unusual case of discordance. nine atcc strains of acanthamoeba and 40 delinked, biobanked, surplus corneal scraping specimens were analyzed for the presence of acanthamoebae with four separate real-time pcr assays. the assay used b ...201526202123
structure and function of a unique pore-forming protein from a pathogenic acanthamoeba.human pathogens often produce soluble protein toxins that generate pores inside membranes, resulting in the death of target cells and tissue damage. in pathogenic amoebae, this has been exemplified with amoebapores of the enteric protozoan parasite entamoeba histolytica. here we characterize acanthaporin, to our knowledge the first pore-forming toxin to be described from acanthamoebae, which are free-living, bacteria-feeding, unicellular organisms that are opportunistic pathogens of increasing i ...201323143413
cb2 receptors in the brain: role in central immune function.recently, it has been recognized that the cannabinoid receptor cb2 may play a functionally relevant role in the central nervous system (cns). this role is mediated primarily through microglia, a resident population of cells in the cns that is morphologically, phenotypically, and functionally related to macrophages. these cells also express the cannabinoid receptor cb1. the cb1 receptor (cb1r) is constitutively expressed at low levels while the cb2 receptor (cb2r) is expressed at higher levels an ...200818037916
conjugative plasmid pld-tex-kl promotes growth of host bacterium legionella dumoffii at low temperatures.legionella (fluoribacter) dumoffii is a resident of various aquatic environments and occasionally causes pneumonia in humans. we found that l. dumoffii strain tex-kl carries a 66-kb circular plasmid. as predicted by the presence of tra genes similar to those of other transferable plasmids, we showed that pld-tex-kl was actually capable of transferring itself to a plasmid-cured derivative of the original strain. unexpectedly, this plasmid-free derivative turned out to be partially defective in te ...200919415237
in vitro susceptibility of acanthamoeba culbertsoni to inhibitors of folate biosynthesis.the effects of different sulphonamides, dihydrofolate reductase inhibitors and other inhibitors of folate metabolism on growth of acanthamoeba culbertsoni in a chemically defined medium are reported. among the sulphonamides, sulphamethoxazole and sulphadiazine were most effective followed by sulphanilamide and sulphaguanidine. inhibition by each sulphonamide was reversed by p-aminobenzoic acid as well as folic acid. 7-methylguanosine, a pteridine synthesis-inhibitor, did not inhibit multiplicati ...19938457798
acanthamoeba interaction with extracellular matrix glycoproteins: biological and biochemical characterization and role in cytotoxicity and invasiveness.acanthamoeba are free-living amoebae that are dispersed in most environments. occasionally, acanthamoeba cause serious human infections, such as keratitis and encephalitis. during the infection process, amoebic adhesion to, and degradation of, host cells and their extracellular matrix (ecm) appear to be important requirements. we examined the interaction of acanthamoeba with the ecm, and related this event to host cell destruction and tissue invasion. pathogenic acanthamoeba culbertsoni differen ...200919527355
acanthamoeba culbertsoni elicits soluble factors that exert anti-microglial cell activity.acanthamoeba culbertsoni is an opportunistic pathogen that causes granulomatous amoebic encephalitis (gae), a chronic and often fatal disease of the central nervous system (cns). a hallmark of gae is the formation of granulomas around the amoebae. these cellular aggregates consist of microglia, macrophages, lymphocytes, and neutrophils, which produce a myriad of proinflammatory soluble factors. in the present study, it is demonstrated that a. culbertsoni secretes serine peptidases that degrade c ...201020605979
acanthamoeba sp. promotes the survival and growth of acinetobacter baumanii.acinetobacter baumanii, which may be found in water, is an important emerging hospital-acquired pathogen. free-living amoebae can be recovered from the same water networks, and it has been shown that these protozoa may support the growth of other bacteria. in this paper, we have studied potential relationships between a. baumanii and acanthamoeba species. two strains of a. baumanii isolated from hospital water were co-cultivated with the trophozoites or supernatants of two free-living amoebae st ...201121395660
identification and quantification of the acanthamoeba species and genotypes from reservoirs in taiwan by molecular techniques.the occurrence of acanthamoeba was investigated from 21 main reservoirs of taiwan with 12 (57.1%) testing positive. analysis of the 18s rrna gene pcr product was performed in order to identify the acanthamoeba isolates. acanthamoeba spp. concentrations were determined according to taqman real-time qpcr. acanthamoeba genotypes of all isolates were identified t4. the species were categorized to acanthamoeba culbertsoni, acanthamoeba polyphaga, acanthamoeba castellanii and acanthamoeba hatchetti. t ...201424388954
Displaying items 1 - 100 of 101