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E L Jarroll

Publications and source records attributed to E L Jarroll.

At least 37 records · Page 2Linked to original sources
PubMed1989

Giardia cyst wall-specific carbohydrate: evidence for the presence of galactosamine.

Gas chromatographic (GC), mass spectrometric (MS), lectin binding and enzymatic analyses of the carbohydrates from Giardia cyst walls, intact cysts and trophozoites were performed to investigate the carbohydrate composition of Giardia cyst walls and to test the hypothesis that the Giardia cyst wall is composed largely of chitin. Galactosamine, verified by MS, was present in Giardia cyst walls and intact cysts (ca. 47 nmol 10(-6) cysts). Since not even trace amounts of it were detected in trophozoites by either GC or lectin binding, galactosamine is hypothesized to be a cyst wall-specific amino hexose. Based on the putative binding affinity of Phaseolus limensis lectin, galactosamine may be present in cyst walls as N-acetylgalactosamine. Neither glucosamine nor sialic acid were detected in as much as 11 mg dry weight of cysts, cyst walls, or trophozoites. Glucose, the most abundant carbohydrate, and ribose were detected in Giardia cysts and trophozoites. Galactose (ca. 10 nmol 10(-6) cysts) was detected in cysts but not in trophozoites. The lack of detectable levels of (1) glucosamine in cyst wall hydrolysates, (2) cyst staining by Calcofluor M2R, (3) endogenous chitinase activity and (4) N-acetylglucosamine when cysts served as a substrate for exogenous chitinase suggests that the Giardia cyst wall is not composed largely of chitin as previously reported. beta-N-Acetylgalactosaminidase, EC 3.2.1.32, activity was detected in cysts and trophozoites and represents the first carbohydrate splitting hydrolase detected in Giardia.

Animals↗
PubMed1989

Giardia lamblia: characterization of proteinase activity in trophozoites.

The proteinase activity of Giardia lamblia trophozoites, Portland 1 strain, was characterized with respect to substrate specificities and inhibitor sensitivities. Proteinase activity with urea-denatured hemoglobin (UDH), alpha-N-benzoyl-DL-arginine-2-naphthylamide (BANA), and alpha-N-benzoyl-argininamide (BAA) as substrates exhibited pH optima of 5.8, 3.8, and 5.0, respectively. For BANA, the apparent Km was 0.20 mM and the Vmax was 2.56 microM. For BAA, the apparent Km was 4.0 mM and the Vmax was 8.69 microM. Dithiothreitol (DTT, 5 mM) enhanced proteinase activity threefold for UDH, fourfold for BAA, and fivefold for BANA. Iodoacetamide, L-tosylamide-2-phenylethyl chloromethyl ketone (TPCK), and N-alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK), each at 1 mM, inhibited proteinase activity by greater than 90% with BANA and BAA. Iodoacetamide inhibited proteinase activity by 35% with UDH; TPCK and TLCK inhibited activity greater than 70% with UDH. Activity on BAA was inhibited by 91% with Zn2+ and activity on UDH was inhibited by 30% with Cu2+. Virtually complete inhibition of proteinase activity on BANA and BAA was obtained with leupeptin and chymostatin at 1 microgram/ml. Pepstatin A, chelators, and other heavy metals had no apparent effect on proteinase activity. Two polypeptide bands (ca. 105 and 40 kDa) indicative of proteinase activity were visualized by sodium dodecyl sulfate-gelatin polyacrylamide gel electrophoresis. The 105 kDa band was visible over the pH range of 4 to 7, but with greater intensity from pH 5 to 7. The 40 kDa band, while present at pH 5, was most intense at pH 6 and 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Respiration in the cysts and trophozoites of Giardia muris.

Cysts and trophozoites of the parasitic protozoon Giardia muris both showed respiratory activity but respiration in cysts was only 10 to 20% that of trophozoites. The O2 dependence of respiration in cysts and trophozoites showed O2 maxima above which respiration decreased. The O2 concentration at which the respiration rate was greatest was higher for cysts than trophozoites. The effects of various inhibitors on cyst and trophozoite respiration suggested that flavoproteins and quinones play some role in respiration. The substrate specificities and the effects of inhibitors on G. muris trophozoites were similar to those observed for Giardia lamblia. Metronidazole, the drug most commonly used in the treatment of giardiasis completely inhibited respiration and motility in trophozoites; however, it had no effect on either respiration or viability in cysts. Menadione, a redox cycling naphthoquinone, stimulated then completely inhibited respiration in cysts and trophozoites; a complete loss of cyst viability or trophozoite motility was also observed. The effects of menadione on G. muris may indicate that redox cycling compounds have potential as chemotherapeutic agents for the treatment of giardiasis.

Animals↗
PubMed1989

Inactivation of gerbil-cultured Giardia lamblia cysts by free chlorine.

Giardia lamblia cysts were harvested from Mongolian gerbils and exposed to free chlorine in buffered water at pH 5, 7, and 9 at 15 degrees C. The contact times required to obtain a 2-log reduction in cyst survival (i.e., a 99% kill) were interpolated from survival curves generated at fixed concentrations of chlorine in the range of 0.25 to about 16 mg/liter. Concentration-time (C.t') products for 99% inactivation ranged from about 120 to nearly 1,500 mg.min/liter. These values are higher than those reported previously for free chlorine using G. lamblia cysts from infected humans. The cysts isolated from gerbils, as with other Giardia cysts, were unusually sensitive to chlorine in alkaline solutions.

Animals↗
PubMed1987

Giardia lamblia: uptake of pyrimidine nucleosides.

The aerotolerant, anaerobic parasite Giardia lamblia, which depends solely upon salvage pathways for its pyrimidine requirements, was found to transport uridine, cytidine, and thymidine by a carrier mediated mechanism. Support for this conclusion comes from the facts that uptake of radiolabeled uridine, cytidine, and thymidine exhibited saturation kinetics, and uptake of these same radiolabeled nucleosides was inhibited by unlabeled homologs, certain pyrimidine analogs, iodoacetate, and N-ethylmaleimide. Uridine and cytidine (perhaps uracil and cytosine also) are postulated to be transported at a common site which is distinct from the site for thymidine transport. Thymidine does appear to bind nonproductively to the uridine/cytidine transport site, but the reverse of this does not appear to occur.

Animals↗
PubMed1984

Giardia lamblia: autoradiographic analysis of nuclear replication.

Giardia lamblia trophozoites, grown in axenic culture, were labeled for various periods of time with [3H]thymidine. After autoradiography, grains were counted over each of the two nuclei in each trophozoite. Analysis of the fraction of trophozoites labeled for each time period resulted in an estimate of a generation time of 15 hr. The DNA synthetic or S phase for a trophozoite in culture was calculated to be 1.8 hr. G1 and G2 periods were determined to be 8.5 and 3 hr, respectively. A comparison of the labeling density between the two nuclei indicated that replication takes place simultaneously in both nuclei for at least 70% of S period. The fraction of asymmetrically labeled trophozoites is consistent with a model in which the nuclei replicate out of phase by 15-30 min, but, due to the small diameter of the nuclei relative to the grain size, the possibility that replication takes place simultaneously in both nuclei of a trophozoite throughout the S phase cannot be ruled out.

Animals↗
PubMed1983

Pyrimidine metabolism in Tritrichomonas foetus.

The pyrimidine metabolism of Tritrichomonas foetus (KV 1) was studied using whole cells and cell homogenates. Pyrimidines and pyrimidine nucleosides were readily incorporated into nucleic acids. Orotate and aspartate were not incorporated into pyrimidine bases. Enzymes of the pyrimidine salvage pathway (i.e., thymidine and uridine phosphorylases and uridine kinase) were detected in trophozoite homogenates, but the activities of de novo pyrimidine synthesis enzymes (i.e., carbamoylphosphate synthase, aspartate transcarbamoylase, dihydroorotase and dihydroorotate dehydrogenase) were below the level of detection in these same homogenates. The evidence presented supports the proposal that T. foetus is incapable of synthesizing pyrimidines de novo but is capable of salvaging preformed pyrimidines and pyrimidine nucleosides from the growth medium and that enzymes of this parasite's pyrimidine salvage pathway are not organelle-associated.

Animals↗
PubMed1982

Pyrimidine metabolism in Giardia lamblia trophozoites.

The pyrimidine metabolism of Giardia lamblia trophozoites (Portland I strain) was studied using whole trophozoites and trophozoite homogenates. Pyrimidines and pyrimidine nucleosides were readily incorporated into nucleic acids. Orotic and aspartic acid incorporations were below the level of detection. Enzymes of the pyrimidine salvage pathway (i.e., thymidine and uridine phosphorylases and thymidine and uridine kinases) were detected in trophozoite homogenates, but the activities of de novo pyrimidine synthesis enzymes (i.e., carbamoyl-phosphate synthase, aspartate transcarbamoylase, dihydroorotase and dihydroorotate dehydrogenase) were below the level of detection in these same homogenates. The evidence presented supports the conclusion that G. lamblia trophozoites appear incapable of synthesizing pyrimidines de novo but are capable of salvaging preformed pyrimidines and pyrimidine nucleosides from the growth medium and the enzymes of this pyrimidine salvage pathway are not organelle associated.

Animals↗
PubMed1982

Energy metabolism of the contagious equine metritis bacterium.

The energy metabolism of the English E-CMO strain of contagious equine metritis bacterium was studied in whole cells and cell extracts. This bacterium appears to have an active Krebs cycle and probably obtains energy by oxidative phosphorylation since glycolysis and the hexose monophosphate pathways appear to be absent. These conclusions are based on the findings that [U-14C]glucose incorporation by this bacterium is below the level of detection, and that respiration is stimulated by Krebs cycle intermediates (i.e., malate, citrate, and succinate), but not by glucose, fructose, maltose, or sucrose. Furthermore, support comes from the fact that enzymes generally associated with the Krebs cycle and electron transport (i.e., malate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase, fumarate hydratase, malate dehydrogenase [decarboxylating], cytochrome oxidase, superoxide dismutase, NADH dehydrogenase, and catalase) were detected. Those enzymes normally associated with glycolysis and the hexose monophosphate pathways (i.e., hexokinase, glucose 6-phosphate dehydrogenase, fructose biphosphate aldolase, glycerol 3-phosphate dehydrogenase, phosphoenolpyruvate carboxykinase, pyruvate kinase, phosphate acetyl transferase, acetate kinase, alcohol dehydrogenase, and lactate dehydrogenase) were below the level of detection.

Animals↗
PubMed1981

Lipid and carbohydrate metabolism of Giardia lamblia.

The lipid and carbohydrate metabolism of Giardia lamblia was studied using trophozoites isolated from a human and axenically grown in vitro in medium containing fetal bovine serum. The phospholipid, fatty acid and neutral lipid composition of the G. lamblia trophozoites was similar to that of the medium. Phosphatidylethanolamine, phosphatidylcholine and sphingomyelin were the major phospholipids detected; monoacyl-, diacyl-, triacylglycerides, sterols, and sterol esters were the major neutral lipids found. Several unidentified glycolipids were also detected. Glucose and threonine were readily incorporated by the trophozoites, but not into cellular phospholipids or sterols. However, approximately 86% of the glucose incorporated into the trophozoites was found in the nucleic acids, and 38% of the threonine incorporated was detected in the cellular proteins. Small amounts of the glucose and threonine were incorporated into glycolipid-containing fractions. Glycerol and acetate were not appreciably incorporated into trophozoites while glycerol 3-phosphate incorporation was not detected. Cholesterol was readily assimilated by the trophozoites; 98% of the incorporated was found in the sterol fraction. Radiorespirometric data suggest that the major routes of glucose metabolism in G. lamblia are via Embden- Meyerhof-Parnas and pentose phosphate pathways. However, endogenous acetate (as acetyl-CoA) formed during the metabolism of glucose is not used for lipid biosynthesis. These findings suggest that G. lamblia trophozoites are incapable of synthesizing cellular phospholipids or sterols de novo, but rather, utilize lipids already present in the medium.

Animals↗
PubMed1981

Effect of chlorine on Giardia lamblia cyst viability.

The effect of chlorine concentration on Giardia lamblia cyst viability was tested under a variety of conditions. The ability of Giardia cysts to undergo excystation was used as the criterion of viability. The experimental variables employed included temperature (25, 15, and 5 degrees C), pH (6, 7, and 8), chlorine-cyst contact time (10, 30, and 60 min), and chlorine concentration (1 to 8 mg/liter). In the pH range studied, cyst survival generally was observed to increase as buffer pH increased. Water temperature coupled with chlorination proved to be important in cyst survival. Results of these experiments at the three temperatures studied can be summarized as follows: at 25 degrees C, exposure to 1.5 mg/liter for 10 min killed all cysts at pH 6, 7, and 8. At 15 degrees C, 2.5 mg of chlorine per liter for 10 min killed all cysts at pH 6, but at pH 7 and 8 small numbers of cysts remained viable after 30 min but not after 60 min. At 5 degrees C, 1 mg of chlorine per liter for 60 min failed to kill all the cysts at any pH tested. At this temperature, 2 mg of chlorine per liter killed all cysts after 60 min at pH 6 and 7, but not at pH 8. A chlorine concentration of 4 mg/liter killed all the cysts at all three pH values after 60 min, but not after 30 min. A chlorine concentration of 8 mg/liter killed all Giardia cysts at pH 6 and 7 after contact for 10 min, and at pH 8 after 30 min. This study points up the role of temperature, pH, and chlorine demand in the halogen treatment of drinking water to destroy cysts. It also raises an epidemiological problem, namely: low water temperatures, where killing of Giardia requires relatively high chlorine concentrations and long contact times, are (i) to be expected in many areas where epidemic waterborne giardiasis has been reported and (ii) particularly conducive to the long-term survival of Giardia cysts.

Animals↗
PubMed1980

Giardiasis.

Explore the source record for details and available documents.

Adult↗
PubMed1980

Dipetalonema from the eye of a man in Oregon, U.S.A. A case report.

A 21-mm filarial worm appeared suddenly in the anterior chamber of the right eye of a 32-year-old man in western Oregon. By a simultaneous irrigation-aspiration procedure, it was removed alive and only slightly damaged and was identified as a female Dipetalonema in the fourth stage of development. It was the third such case to be reported from western Oregon. In this and one other case the worms were morphologically similar to adult worms identified as Dipetalonema arbuta Highby 1943 from the body cavity of the porcupine (Erethizon dorsatum) and a similar species, Dipetalonema sprenti Anderson 1953, from the body cavity of the beaver (Castor canadensis).

Adult↗
PubMed1980

Giardia cyst destruction: effectiveness of six small-quantity water disinfection methods.

None of the available chemical methods for disinfecting drinking water has ever been tested for its ability to destory Giardia cysts. We tested the ability of six such methods to act against Giardia, using excystation as the criterion of viability. Two water qualities (cloudy and clear) and two temperatures (3 and 20 degrees C) were tested. At 20 degrees C, using cloudy and clear water, all of the method proved completely effective. However, at 3 degrees C, in cloudy water one method ("saturated" iodine) was less than completely effective, and in clear water four methods (bleach, Globaline, tincture of iodine and "saturated" iodine) failed to destory all of the cysts. The failure of these methods appears to be related to either an insufficient halogen residual or contact time. This study underlines the importance of considering water temperature when employing halogen disinfection methods.

Disinfection↗
PubMedDate not supplied

Biochemistry and metabolism of Giardia.

Giardia lamblia, an aerotolerant anaerobe, respires in the presence of oxygen by a flavin, iron-sulfur protein-mediated electron transport system. Glucose appears to be the only sugar catabolized by the Embden-Meyerhof-Parnas and hexose monophosphate pathways, and energy is produced by substrate level phosphorylation. Substrates are incompletely oxidized to CO2, ethanol and acetate by nonsedimentable enzymes. The lack of incorporation of inosine, hypoxanthine, xanthine, formate or glycine into nucleotides indicates an absence of de novo purine synthesis. Only adenine, adenosine, guanine and guanosine are salvaged, and no interconversion of these purines was detected. Salvage of these purines and their nucleosides is accomplished by adenine phosphoribosyltransferase, adenosine hydrolase, guanosine phosphoribosyltransferase and guanine hydrolase. The absence of de novo pyrimidine synthesis was confirmed by the lack of incorporation of bicarbonate, orotate and aspartate into nucleotides, and by the lack of detectable levels of the enzymes of de novo pyrimidine synthesis. Salvage appears to be accomplished by the action of uracil phosphoribosyltransferase, uridine hydrolase, uridine phosphotransferase, cytidine deaminase, cytidine hydrolase, cytosine phosphoribosyltransferase and thymidine phosphotransferase. Nucleotides of uracil may be converted to nucleotides of cytosine by cytidine triphosphate synthetase, but thymidylate synthetase and dihydrofolate reductase activities were not detected. Uptake of pyrmidine nucleosides, and perhaps pyrimidines, appears to be accomplished by carrier-mediated transport, and the common site for uptake of uridine and cytidine is distinct from the site for thymidine. Thymine does not appear to be incorporated into nucleotide pools. Giardia trophozoites appear to rely on preformed lipids rather than synthesizing them de novo.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Carbohydrate and amino acid analyses of Giardia muris cysts.

Intact Giardia muris cysts were subjected to consecutive chloroform/methanol and 2% sodium dodecyl sulfate (SDS) extractions, and to amyloglucosidase treatment. The SDS-insoluble, amyloglucosidase-fast cyst walls (ACW) were further incubated with chymotrypsin, trypsin, papain, or pronase. Low voltage scanning electron microscopy revealed no discernible change in the ultrastructure of the filamentous layer of the cyst wall following any of these treatments. Affinity for cyst wall-specific monoclonal antibody (Meridian Diagnostics, Cincinnati, OH) was also retained after all treatments. Periodic acid-Schiff staining and gas chromatography/mass spectrometry (GC/MS) of intact and treated cyst hydrolysates showed a significant reduction in the amount of glucose associated with the cyst (72 nmoles/10(6) intact cysts vs 1.9 nmoles/10(6) ACW) as a result of amyloglucosidase treatment, indicating that glucose is stored within Giardia as an SDS-insoluble polymer. Galactosamine was identified by GC/MS as the predominant sugar associated with both the ACW and the proteinase treated ACW (42 nmoles/10(6) ACW). High performance liquid chromatographic analysis of amino acids from intact and treated cyst hydrolysates revealed a marked reduction, but not elimination, of detectable quantities of identifiable amino acid residues (255 nmoles/10(6) intact cysts vs 6.8 nmoles/10(6) proteinase treated ACW). These results suggest that the filamentous layer of the cyst wall is primarily a carbohydrate peptide complex.

Amino Acids↗