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At least 19 recordsLinked to original sources
PubMed1998

Correlation between surface water contamination with amoeba and the onset of symptoms and diagnosis of amoeba-like keratitis.

AIM: A seasonal variation was noted in the incidence of amoeba-like keratitis in Iowa. The level of contamination of amoeba in surface water has been found previously to vary on a monthly basis for Tulsa, Oklahoma, a region with a similar climate. It was hypothesised that this seasonal variation in amoeba-like keratitis correlated with the concentration of amoeba in surface water. METHODS: The monthly variation in the onset of symptoms was determined and date of diagnosis in 137 cases of amoeba-like keratitis, in Iowa, from January 1993 to the end of December 1996. RESULTS: Over a 4 year period a significant variation was found, on a monthly basis, in the onset of symptoms as reported by the patient. There were two peak periods per year when the onset of symptoms was most frequent: June and November. This corresponded closely with the concentration of amoeba in the ground water reported for a similar region in the mid-west (Tulsa, Oklahoma). A yearly increase was found in the number of cases diagnosed from January 1993 to the end of December 1996. CONCLUSIONS: This study supports the hypothesis that the concentration of amoeba in surface water may influence the rate of an amoeba-like keratitis infection.

Acanthamoeba↗
PubMed1978

[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 amoebas trophozoites as an immunizing dose three times with one week interval, and large dose group received 10(6) live or dead trophozoites respectively. The control group received physiologic saline or medium for culture of free-living amoebas intravenously. Antiserum was collected 4 times at interval of 3 days in the first 10 days, and also up to 2 months later. In the group immunized with live Acanthamoeba culbertsoni, fluorescent antibody titer was higher than in the group of dead one, and also in the large dose group than in the small dose group. Antibody titer of anti-Naegleria fowleri serum in the large dose group showed no difference by the source of amoeba antigen; live or dead. But in the small dose group, antibody titer was higher in the immunized with live Naegleria fowleri than in the group with dead one. No cross reactivity was demonstrated between the Acanthamoeba and Naegleria. And no cross reaction was observed when the free-living amoebas antigens were tested against human sera of amoebiasis, paragonimiasis and clonorchiasis.

Journal Article↗
PubMed2006

Biodiversity of amoebae and amoeba-resisting bacteria in a hospital water network.

Free-living amoebae (FLA) are ubiquitous organisms that have been isolated from various domestic water systems, such as cooling towers and hospital water networks. In addition to their own pathogenicity, FLA can also act as Trojan horses and be naturally infected with amoeba-resisting bacteria (ARB) that may be involved in human infections, such as pneumonia. We investigated the biodiversity of bacteria and their amoebal hosts in a hospital water network. Using amoebal enrichment on nonnutrient agar, we isolated 15 protist strains from 200 (7.5%) samples. One thermotolerant Hartmannella vermiformis isolate harbored both Legionella pneumophila and Bradyrhizobium japonicum. By using amoebal coculture with axenic Acanthamoeba castellanii as the cellular background, we recovered at least one ARB from 45.5% of the samples. Four new ARB isolates were recovered by culture, and one of these isolates was widely present in the water network. Alphaproteobacteria (such as Rhodoplanes, Methylobacterium, Bradyrhizobium, Afipia, and Bosea) were recovered from 30.5% of the samples, mycobacteria (Mycobacterium gordonae, Mycobacterium kansasii, and Mycobacterium xenopi) were recovered from 20.5% of the samples, and Gammaproteobacteria (Legionella) were recovered from 5.5% of the samples. No Chlamydia or Chlamydia-like organisms were recovered by amoebal coculture or detected by PCR. The observed strong association between the presence of amoebae and the presence of Legionella (P < 0.001) and mycobacteria (P = 0.009) further suggests that FLA are a reservoir for these ARB and underlines the importance of considering amoebae when water control measures are designed.

Alphaproteobacteria↗
PubMed1980

Pinocytosis and locomotion of amoebae. XV. Visualization of Ca++-dynamics by chlorotetracycline (CTC) fluorescence during induced pinocytosis in living Amoeba proteus.

The dynamics of Ca++ during induced pinocytosis were studied in Amoeba proteus using chlorotetracycline (CTC). The fluorescence of the Ca++ - CTC-complex was monitored by an image intensification system, which has certain advantages over standard equipment: (1) Living cells are not subjected to the damaging influence of intensive microscopic illumination, (2) fluorescent probes are not bleached during observation, and (3) the rapid dynamics of the Ca++ -fluxes can be recorded using short exposure times. The results demonstrate the existence of Ca++ bound to intracellular and extracellular sites of the cell membrane complex in normal locomoting and pinocytotic Amoeba proteus. The application of cations inducing pinocytosis causes a rapid decrease in the external CTC-fluorescence probably due to a release of Ca++ from the mucous layer. The degree of fluorescence intensity is correlated with the capacity of pinocytotic channel formation, i.e., the fluorescence decreases as the number of channels increases. During the phase of vesiculation a distinct fluorescence mainly restricted to the basal region of the channels is observed. Intracellular Ca++ was detected in close vicinity to the plasma membrane after both microinjection and external application of CTC. The internal CTC-fluorescence is slightly decreased during the induction phase of pinocytosis. The observations are in good agreement with previous results on the localization of Ca++ -binding sites at the plasma membrane of Amoeba proteus and demonstrate the important role of Ca++ -fluxes for the process of pinocytosis.

Amoeba↗
PubMed1976

Inhibition of cell division in amoebae: the incorporation of tritiated precursors into Amoeba proteus after the injection of non-homologous cytoplasm.

The injection of non-homologous cytoplasm into any strain of large free-living amoebae leads to a 60% inhibition of division amongst recipient cells. When the post-microsomal supernatant fraction of Amoeba discoides was injected into A. proteus, this inhibition of division was as high as 95%. The incorporation of tritiated precursors, either [3H]uridine or 3H-amino acids, into these inhibited amoebae was studied at various times after the injection of the inhibitory material using autoradiography. When cells were grown in [3H]uridine, autoradiographs indicated that RNA synthesis had ceased 2 days after the injection of non-homologous material. However, if [3H]uridine was injected into the inhibited cells, some synthesis of RNA could be detected up to 4 days after the injection of inhibitor. These results suggested that uptake of [3H]uridine was impaired and that one site of action of the inhibitory molecules was RNA synthesis for membrane components. Experiments with a variety of 3H-amino acids suggested that protein synthesis continued for at least 9 days after the injection of non-homologous cytoplasm, and that in these cells some informational RNA molecules were long-lived. There seemed to be accumulation of material containing [3H]lysine in the nuclei of control cells taken at random from cultures, and this was seen in the nuclei of inhibited cells 1 day after injection. However, 2 days after the injection of inhibitor, no accumulation of [3H]lysine-containing material was found in the nuclei.

Amino Acids↗
PubMed2000

[Electrophoretic forms of glucose-6-phosphate dehydrogenase, acid phosphatase and esterase in Amoeba species amoebas].

Glucose-6-phosphate dehydrogenase (G6PD), acid phosphatase and esterases in free-living amoebae of 7 Amoeba species were investigated with the use of disc-electrophoresis in polyacrylamide gel. The evidence provided is suggestive that the electrophoretic isoenzyme patterns of acid phosphatase and esterases (and G6PD in some cases), in addition to a few morphological characters, can serve as a taxonomic criterion for species identification within this genus, as well as for revealing erroneously classified species and strains. It is suggested that A. indica is an independent species whose preliminary diagnosis has been given in this paper. It is concluded that A. discoides and A. lescherae are strains of A. proteus, rather than two independent species. A and As-102 amoebian strains, kept in the collection of protozoan strains and species of the Institute of Cytology RAS and referred to as strains of A. proteus, belong in reality to another Amoeba species and even to another genus within the family Amoebidae. This conclusion has been documented by results of our analysis of electrophoretic patterns of acid phosphatase and esterases in these strains.

Acid Phosphatase↗
PubMed1980

Informational molecules in amoebae studies of template utilization by the DNA polymerase activities of Amoeba discoides.

Studies have shown that certain strain-specific characters of large, free-living amoebae may be influenced by the microinjection of non-homologous low molecular weight RNAs. To investigate the mechanisms involved in 'information' transfer, the template preferences of partially purified DNA polymerase activities isolated from Amoeba discoides have been studied. After passage through Sephadex G-200, DNA polymerase activities from whole homogenates could utilize both 'activated' calf thymus DNA and the synthetic ribohomopolymer poly rA oligo d(pT)10 as templates. Fractionation using different saturations of (NH4)2SO4 showed that there was no detectable poly A d(pT)10-directed DNA polymerase activity in the extra-mitochondrial cytoplasm, and the ability to utilize this template appeared to be located in the nuclei. Nuclear protein passed through short (30 cm) columns of Sephadex G-200 showed DNA polymerase activities which could use both synthetic and natural RNA as templates, but little activity was detected when using longer (70 cm) columns, although DNA-directed DNA polymerase activities were more clearly defined. Use of DEAE-cellulose only revealed a low (1--3%) activity with poly A d(pT)10 compared to the activity observed using 'activated' calf thymus DNS. DNA polymerase activities of amoebae showed a response to added RNA templates which depended on the purity of the enzyme preparation, and the possibility that these enzymes are involved in 'information' transfer cannot be ruled out.

Amoeba↗
PubMed1978

[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 C until use. The immobilization test was performed. One drop of amoeba suspension was mixed with the test serum on slide and observed the mobile state under microscope. 1. Maximal immobilizing phenomenon observed in 30 minutes and, then gradually recovered to normal state. 2. Inactivation of antiserum at 56 degrees C for 30 minutes did not affect the immobilization phenomenon. 3. The immobilization rates decreased by the serial dilution of antiserum. At dilution more than 1:8, the immobilization was almost the same as in the normal serum. 4. The immobilizing antibody in anti-Acanthamoeba culbertsoni rabbit serum showed highest titre in 3rd day after booster immunization and from first to 6th week in anti-Naegleria fowleri rabbit serum. 5. Cross matching of Acanthamoeba culbertsoni and Naegleria fowleri showed antigenic difference of the two species. It is suggested that the immobilization reaction may be of value as a supplementary test in the diagnosis of primary amoebic meningoencephalitis.

Journal Article↗
PubMed1982

Studies of the DNA of Amoeba proteus and Amoeba indica.

1. The G + C content of the DNAs of Amoeba proteus and Amoeba indica was determined by buoyant density gradient centrifugation. 2. Generally, different clones of the same strains did not differ in the G + C content of their main DNA or their satellite DNA. 3. The G + C content of the main DNA of the TD and XD strains of A. proteus were the same (25.3 and 29.3% respectively) as were the G + C contents of the satellite DNA (54.7 and 61.8% respectively). 4. The main and satellite DNAs are reversed for the F strain of A. proteus and the I strain of A. indica; the G + C contents of the main DNA being 57.4 and 59.8% respectively and those of the satellite DNA being 23.5 and 28.4% respectively. 5. The heterologous hybrids produced by nuclear transplantation between the A strain of A. proteus and the I strain of A. indica have the same G + C content in their main and satellite DNAs as do their cytoplasmic parents. 6. The data suggest that the occurrence of phenotypic variations does not necessarily mean an alteration in the G + C content of either main or satellite DNA. 7. There is also evidence that the G + C content of these DNAs in under cytoplasmic control.

Amoeba↗
PubMed1983

Pinocytosis and locomotion of amoebae. XIX. Immunocytochemical demonstration of actin and myosin in Amoeba proteus.

The spatial distribution of cytoplasmic actin and myosin in 1. normal locomoting, 2. immobilized, and 3. pinocytosing Amoeba proteus was demonstrated by indirect immunofluorescence microscopy. In orthotactic and polytactic cells fixed during normal locomotion actin is mainly located in a cortical layer delineating the granuloplasm from the peripheral hyaloplasm. In cell areas lacking a hyaloplasmic sheet the actin layer immediately borders the plasma membrane. The amount of actin within the continuous layer seems to increase from the advancing front to the middle cell region and to decrease again toward the uroid. The distribution of myosin is largely congruent to the display of actin, with the exception that the myosin-based fluorescence of the cortical layer gradually increases from the front to the uroid. A considerable amount of actin and myosin is also distributed around the nucleus and the contractile vacuole. In immobilized cells contracted by the external application of 10(-4)M procaine hydrochloride the cortical layer distinctly increases in thickness. In contrast to normal locomoting cells actin and myosin show a uniform distribution within the cell cortex along the entire surface. In pinocytosing cells, up to three cortical layers conspicuously rich in actin are produced during the process of channel formation. One of these layers is located in close proximity to the plasma membrane of the pinocytotic channels and the vacuoles. The immunocytochemical results are discussed with respect to earlier observations on the distribution of actin and myosin in Amoeba proteus as obtained by other methods.

Actins↗
PubMed1981

[Taxonomy-trial of the free-living amoebae belonging to the genus Acanthamoeba (Protozoa, Amoeba) by means of the cyst-features in scanning electron microscopy (author's transl)].

In order to verify the contribution of scanning electron microscopy to the taxonomic study of free-living amoebae, the authors studied at the encysted stage 21 strains of free-living amoebae representing 20 species (1 Naegleria gruberi, 1 Tetramitus rostratus and 18 Acanthamoeba sp). The method utilized is satisfactory for distinguishing the different genera. Using optical methods, it is possible to differentiate three groups (I, II, III) of Acanthamoeba, including 3, 10 and 5 species, respectively. The results obtained with scanning electron microscopy, however, are less precise. In particular, group II can be divided into only four sub-groups and group III into only two sub-groups and one species, A. culbertsoni. The method remains valid for group I.

Amoeba↗
PubMed1997

ADHESION-DEPENDENT F-ACTIN PATTERN IN AMOEBA PROTEUS AS A COMMON FEATURE OF AMOEBAE AND THE METAZOAN MOTILE CELLS

Adhesion and movement of Amoeba proteus are both dependent on the appropriate arrangement of the F-actin cytoskeleton and on the presence of the cell nucleus. In this study the F-actin organization was examined by routine FITC-phalloidin staining and confocal laser microscopy in intact amoebae and in their nucleated and anucleated fragments, at different levels of cell adherence to the substratum. In the adhering and migrating intact cells and nucleated cell fragments dot-like aggregates of F-actin are scattered over the ventral side at sites close to the substratum. In the case of de-adhesion of nucleated specimens this pattern disappears and F-actin is accumulated in the cell centre and/or dispersed in the cytoplasm. The same actin distribution, without ventral dots, is found in the anucleated fragments which usually fail to attach to the substratum. Re-adhesion of anucleated fragments, induced by a modified substratum or spontaneous, is accompanied by restoration of actin dots at the lower cell side. It is concluded that: (1) adhering specimens of A. proteus display the same dot-like actin pattern on the ventral cell side, as many metazoan motile cells; (2) organization or disorganization of this pattern may occur independently of the presence of the cell nucleus, under the control of cell adhesion to the substratum. Copyright 1998 Academic Press Limited

Journal Article↗
PubMed1983

Isolation of Legionella pneumophila from clinical specimens via amoebae, and the interaction of those and other isolates with amoebae.

The development of an amoebal enrichment method, for the recovery of viable Legionella pneumophila from clinical materials is described. The method has been used successfully in five of six cases of Legionnaires' disease in which L pneumophila was isolated. Studies on those L pneumophila isolates led to the discovery that virulent legionellae are attracted to, and attack suitable host amoebae, rather than infection following chance ingestion.

Aged↗
PubMed1975

[Incompatibility during transplantation of nuclei in amoeba. IV. Transplantation compatibility in different strains of Amoeba proteus].

Seven laboratory Amoeba proteus strains of different origin were tested for their transplantation compatibility (i.e. viability of artificially produced heterokaryons) in all possible pair combinations. Incompatible combinations (14) as well as completely compatible ones (7) were found. Compatibility was distributed among strain combinations non-randomly. All the strains studied could be classified into three groups with respect to compatibility ("compatibility groups") involving 1, 2 and 4 strains, respectively. Within the third group any pair of strains was compatible, as well as both strains of the second group. On the contrary, any strains from different groups were always incompatible. Possible nature of the compatibility groups is discussed. It is suggested that they might be analogous to syngens of Ciliates.

Animals↗