• Molecules and Cells
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• v.20 no.3
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• pp.371-377
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• 2005

The roles that accessory gene products play in activating the Helicobacter pylori urease apoprotein were examined. The activity of the urease apoprotein increased in the following order when it was expressed with the accessory genes: ureG < ureGH < ureFGH < ureEFGH < ureIEFGH. Moreover, stepwise additions of ureE and ureI to ureFGH significantly increased urease activity. Urease apoproteins coexpressed with ureFGH, ureEFGH, and ureIEFGH had similar low chymotrypsin susceptibilities. In vivo and in vitro activation studies showed that the cooperative effect of the accessory proteins involved processes in which the UreFGH complex, UreE, and UreI were implicated. Thus, the UreFGH complex may serve to alter the conformation of the apoprotein into one that is more competent to assemble a stable metallocenter, and that facilitates cooperative effects.

• Fisheries and Aquatic Sciences
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• v.7 no.1
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• pp.10-15
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• 2004

A total of 52 pathogenic Vibrio strains was isolated from the Gwangan Beach during summer in 2003. The isolated vibrios were composed of 6 different species: V. parahaemolyticus, V. cholerae non O1, V. fluvialis, V. vulnificus, V. alginolyticus, and V. mimicus. V. parahaemolyticus was most predominant as $46\%$ (24/52), V. cholerae non O1 was the second with $23\%$ (12/52), and V. fluvialis was the third with $17\%$ (9/52). Among the isolated strains, 22 strains showed hemolytic, proteolytic or ureolytic activity. Eight strains showed both hemolysin and protease activities, and either 6 strains showed only hemolysin activities and 7 strains only protease activities. Only one strain of V. parahaemolyticus isolates showed urease activity. The urease-positive V. parahaemolyticus strain (V. parahaemolyticus S25) showed the same biochemical characteristics as the reference strain, V. parahaemolyticus KCTC 2471 (urease­negative) except for urease production. To compare the degree of virulence of Vibrio strains having different pathogenic factors, hemolysin, protease, or urease-positive strains were injected into groups of 10 each of ICR mice (7- to l0-week-old male). The lethal rate of urease-positive V. parahaemolyticus S25 was significantly high, being $70\%$. Protease-positive strains showed $40-60\%$ of lethal rate. Hemolysin-positive strains showed no mortality, similar to non-pathogenic V. parahaemolyticus KCTC 2471 and V. parahaemolyticus FM12.

• Journal of Veterinary Clinics
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• v.18 no.4
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• pp.329-333
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• 2001

Evaluation on the diagnostic performances of urease test and polymerase chain reaction (PCR) for detection of Helicobacter species infection in dogs has rarely been performed in research with site-specific situations, although assessing diagnostic tests is an essential part prior to its practical use in a variety of clinical settings. The clinical value of a diagnostic test may be misjudged and comparisons between different tests may yield misleading conclusions when high within-patient correlations are present. We applied a conceptually simple statistical approach to estimate the sensitivity and specificity of urease test and PCR for detection of Helicobacter species infection in dogs. This approach assumes that responses from three different sampling sites within an animal are correlated where unit for statistical analysis is the site rather than the animal. The sensitivity and specificity of urease test was 0.74% (95% confidence interval, 0.64-0.84) and 0.87 (95% CI, 0.67-1.00), respectively. For PCR, the sensitivity was 0.95(95% CI, 0.89-1.00) and specificity 0.90 (95% CI, 0.70-1.00). Two tests were almost equally specific. Urease test, however, has a lower diagnostic accuracy and thus should only be used after careful validation in terms of sensitivity.

• Archives of Pharmacal Research
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• v.9 no.3
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• pp.163-167
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• 1986

Twenty six urea analogues, most of which have already been approved for human use, were tested for their antiurease activity in vitro. Cell-free extracts obtained from a clinical isolate of Proteus mirabilis was used as the source of enzyme. Acetohydroxamic acid which is a proven potent urease inhibitor but not approved for human use was again shown to be the most active compound among the tested. Phenacemide, cycloserine, and deferoxamine were demonstrated to be moderate inhibitors. Oxtetracycline, trimethoprim, and cefamandole revealed a demonstrable antiruease activity, but only at very high concentrations. The antiurease activity of cycloserine, trimethoprim, and cefamandole was pH dependent-only active at acidic pH. The inhibitory activity of acetohydroxamic acid however was independent of change in pH. The inhibitory activity of acetohydroxamic acid however was independent of change in pH. Hydrogen ion concentration plays an important role in urease activity and acidification (pH 5. 5) alone eliminates approximately 65% of the enzymic activity. Adjustment of pH therefore appears to be an important adjunct in reducing unrease activity and should always be studied to maximize the effcacy of antiurease compounds under investigation.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2741-2747
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• 2012

A new series of 2,5-disubstituted-1,3,4-thiadiazoles 6a-i was synthesized by overnight stirring various 1,4-disubstituted thiosemicarbazides 5a-i in polyphosphoric acid followed by neutralization. The structures of newly synthesized compounds 5a-i and 6a-i were characterized by IR, $^1H$ and $^{13}C$ NMR, elemental analysis and mass spectrometric studies. All the synthesized compounds were evaluated for their urease and acetylcholine esterase inhibition activities. Thiosemicarbazides 5a-i are found to possess excellent potential for urease inhibition, more than the standard drug. Thiosemicarbazides 5a-i are more potent urease inhibitor than their cyclic analogues thiadiazoles 6a-i. Almost all of the compounds are excellent inhibitors of acetylcholine esterase. The inhibition of acetylcholine esterase of compounds 5a, 5c, 5d, 5g, 5i, 6e, 6f, 6g, and 6i is much more than that of standard drug.

• Journal of Microbiology and Biotechnology
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• v.19 no.12
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• pp.1565-1568
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• 2009

Purified Helicobacter pylori urease displayed a sigmoid curve in the plot of velocity versus [S] at urea concentrations less than 0.1mM. Under conditions where preservatives, glycerol, or polyethylene glycol (PEG) were added to the enzyme reaction, the substrate hydrolysis was consistent with Michaelis-Menten kinetics, with a $K_m$ of $0.21\;{\pm}\;0.06\;mM$ and a $V_{max}$ of $1,200\;{\pm}\;300\;{\mu}mol\;min^{-1}\;mg^{-1}$. However, at saturating substrate concentrations, the kinetic parameters of H. pylori urease were unaffected by the presence of the preservatives, and enzyme catalysis conformed to Michaelis-Menten kinetics. The Hill coefficients of the enzyme-catalyzed urea hydrolysis in the presence and absence of PEG were 1 and 2, respectively. Based on these findings, we suggest that H. pylori urease may exist in aggregated and dissociated forms, each with intact function but differing kinetics that may be of importance in maximizing urea breakdown at varying urea concentrations in vivo.

• Food Engineering Progress
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• v.13 no.4
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• pp.251-261
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• 2009

In vitro physiological functions such as jack bean (Canavalia ensiformis) urease inhibitory activity and retarding effect of glucose/bile acid of Aloe vera gel concentrated by the optimized DIS (Dewatering Impregnation & Soaking) process conditions were examined. Urease inhibitory activity of DIS aloes ranged from 84.6 to 94.4%, which was similar to or higher than 86.3% of fresh aloe. Also, urease inhibitory activity of DIS aloes was maintained at initial levels after heat treatment (90$^{\circ}C$, 10 min.) and drying treatment (freeze or hot air drying). Urease inhibition pattern from Lineweaver-Burk plot indicated general non-competitive inhibition, and inhibition constants ($K_{IE}$ and $K_{IES}$) of DIS aloes were 41-149 and 87-163 $\mu$L/mL, respectively. DIS(glucose) and DIS(polyethylene glycol) exhibited the highest retarding effect of glucose and bile acid. Their retarding effects were about 1.6 and 1.8 folds higher than that of fresh aloe after 0.5 and 1 hr of the dialysis, respectively. Conclusively, the above in vitro physiological functions of Aloe vera gel concentrated by DIS process suggested that aloe products treated with DIS would have the potential benefits for protection against Helicobacter pylori and reduction of blood glucose and cholesterol levels.

• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.1992-1998
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• 2018

In 2015, Bacillus paralicheniformis was separated from B. licheniformis on the basis of phylogenomic and phylogenetic studies, and urease activity was reported as a phenotypic property that differentiates between the two species. Subsequently, we have found that the urease activity of B. paralicheniformis is strain-specific, and does not reliably discriminate between species, as strains having the same urease gene cluster were identified in B. licheniformis and B. sonorensis, the closest relatives of B. paralicheniformis. We developed a multilocus sequence typing scheme using eight housekeeping genes, adk, ccpA, glpF, gmk, ilvD, pur, spo0A, and tpi to clearly identify B. paralicheniformis from closely related Bacillus species and to find a molecular marker for the rapid identification of B. paralicheniformis. The scheme differentiated 33 B. paralicheniformis strains from 90 strains formerly identified as B. licheniformis. Among the eight housekeeping genes, spo0A possesses appropriate polymorphic sites for the design of a B. paralichenofomis-specific PCR primer set. The primer set designed in this study perfectly separated B. paralicheniformis from B. licheniformis and B. sonorensis.

• Geomechanics and Engineering
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• v.17 no.5
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• pp.421-427
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• 2019

Coastal erosion is becoming a significant problem in Greece, Bangladesh, and globally. For the prevention and minimization of damage from coastal erosion, combinations of various structures have been used conventionally. However, most of these methods are expensive. Therefore, creating artificial beachrock using local ureolytic bacteria and the MICP (Microbially Induced Carbonate Precipitation) method can be an alternative for coastal erosion protection, as it is a sustainable and eco-friendly biological ground improvement technique. Most research on MICP has been confined to land ureolytic bacteria and limited attention has been paid to coastal ureolytic bacteria for the measurement of urease activity. Subsequently, their various environmental effects have not been investigated. Therefore, for the successful application of MICP to coastal erosion protection, the type of bacteria, bacterial cell concentration, reaction temperature, cell culture duration, carbonate precipitation trend, pH of the media that controls the activity of the urease enzyme, etc., are evaluated. In this study, the effects of temperature, pH, and culture duration, as well as the trend in carbonate precipitation of coastal ureolytic bacteria isolated from two coastal regions in Greece and Bangladesh, were evaluated. The results showed that urease activity of coastal ureolytic bacteria species relies on some environmental parameters that are very important for successful sand solidification. In future, we aim to apply these findings towards the creation of artificial beachrock in combination with a geotextile tube for coastal erosion protection in Mediterranean countries, Bangladesh, and globally, for bio-mediated soil improvement.

• Proceedings of the Microbiological Society of Korea Conference
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• 2001.11a
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• pp.26-36
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• 2001

A novel approach of microbiologically-enhanced crack remediation (MECR) has been initiated and evaluated in this report. Under the laboratory conditions, Bacillus pasteurii was used to induce $CaCO_3$ precipitation as the microbial urease hydrolyzes urea to produce ammonia and carbon dioxide. The ammonia released in surroundings subsequently increases pH, leading to accumulation of insoluble $CaCO_3$. Scanning electron micrography (SEM) and x-ray diffraction (XRD) analyses evidenced the direct involvement of microorganisms in $CaCO_3$ precipitation. In biochemical studies, the primary roles of microorganisms and microbial urease were defined. Furthermore, the role of urease in $CaCO_3$ precipitation was characterized utilizing recombinant Escherichia coli that encoded B. pasteurii urease genes in a plasmid. Microorganisms immobilized in polyurethane (PU) polymer were applied to remediate concrete cracks. Although microbiologically- induced calcite precipitation enhanced neither the tensile strength nor the modulus of elasticity of the PU polymer, cement mortar whose crack was remediated with the cemaden polymer showed a significant increase in compressive strength. Through detailed investigation, MECR showed an excellent potential in cementing cracks in granite, concrete, and beyond.