• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.1
• /
• pp.84-90
• /
• 2011

It is imperative to study the hydrolysis of urea in high saline-sodic condition of a newly reclaimed tidal land in order to overcome the problems associated with use of urea fertilizer. The methodology adopted in this study tried to get a convenient way of estimating rate for N transformation needed in N fate and transport studies by reviewing pH and salt contents which can affect the microbial activity which is closely related to the rate of urea hydrolysis. The hydrolysis of urea over time follows first-order kinetics and soil urease activity in reclaimed soils will be represented by Michaelis-Menten-type kinetics. However, high pH and less microorganisms may delay the hydrolysis of urea due to decrease in urease activity with increasing pH. Therefore, the rate of urea hydrolysis should adopt $V_{max}$ referring enzyme activity ($E_0$) accounting for urease concentration which is indicative for urea hydrolysis, especially in a high saline and sodic soils.

• Korean Journal of Environmental Agriculture
• /
• v.20 no.5
• /
• pp.325-329
• /
• 2001

Soil enzyme and microbial activities are affected by fertilizer and compost applications and can be used as sensitive indicators of ecological stability. Microbial population and soil enzymes viz., dehydrogenase, urease, acid phosphatase and aryl-sulphatase were determined in the long-term fertilizer and compost applied paddy soil. Soil samples were collected from the four treatments (control, compost, NPK and compost+NPK). Long-term NPK+compost application significantly increased activities of urease, dehydrogenase and acid phosphatase than all other treatments. The compost application enhanced activities of urease, dehydrogenase and acid phosphatase than the NPK application. However, arylsulfatase activity was not significantly different between compost and fertilizer application. The highest microbial population was recorded in the NPK+compost treatment. The compost application also resulted in higher microbial population than the NPK application. The above results indicate that ecological stability could be maintained by application of compost alone or with NPK.

• Journal of the Korean Chemical Society
• /
• v.36 no.4
• /
• pp.496-503
• /
• 1992

An ISFET urea sensor was fabricated by immobilizing the urease using photosensitive polymer, poly(vinyl alcohol)-SbQ on the H$^+$ sensing $Si_3$$N_4$ thin film of pH-ISFET. The sensor could determine the urea concentration in the range of 1∼50 mg/dl with fast response and good repeatability. For its application to clinical analysis, the interferences of the various materials which cause inhibition in urease catalytic reactions in blood was investigated. The results of the urea measurements in blood plasma using the ISFET urea sensor were compared with these of conventional spectrophotometric method.

• Food Science and Biotechnology
• /
• v.15 no.3
• /
• pp.466-468
• /
• 2006

The antimicrobial effect of a novel flavonoid (7-O-butyl naringenin) on Helicobacter pylori ATCC 26695 and its inhibitory effects on the urease activity of the strain were evaluated by comparing with quercetin and naringenin. H. pylori was cultured with brain heart infusion supplemented with 5% horse serum at $37^{\circ}C$ under 10% $CO_2$ atmosphere and the inhibitory effects of flavonoids against the strain were detected using micro-plate methods. During 12 hr of incubation time, the optical densities of phenol red reduced (pink color) in the urea broth by producing ammonia were detected at 560 nm with a spectrophotometer. The results indicated that both quercetin and 7-O-butyl naringenin were effective against the growth of H. pylori. Moreover, inhibitory effect of 7-O-butyl naringenin on the growth of H. pylori was about two-fold higher than quercetin at the same concentration. With regard to H. pylori urease activity, 7-O-butyl naringenin had a greater inhibitory effect than did naringenin or quercetin at the same concentration.

• Childhood Kidney Diseases
• /
• v.25 no.2
• /
• pp.112-116
• /
• 2021

Hyperammonemia is mainly caused by diseases related to liver failure. However, there are also non-hepatic causes of hyperammonemia, such as urinary tract infection (UTI) due to urease-producing organisms. Urease production by these bacteria induces a hydrolysis of urinary urea into ammonia that can cross the urothelial cell membrane and diffuse into blood vessels, leading to hyperammonemia. Delayed diagnosis and treatment of hyperammonemia can lead to lethal encephalopathy that can cause brain damage and life-threatening conditions. In the presence of obstructive uropathy, UTI by urease-producing bacteria can lead to more severe hyperammonemia due to enhanced resorption of ammonia into the systemic circulation. In this report, we present a case of acute severe hyperammonemic encephalopathy leading to brain death due to accumulation of ammonia in blood caused by Morganella morganii UTI in a 10-year-old girl with cloacal anomaly, causing obstructive uropathy even after multiple corrections.

• Geomechanics and Engineering
• /
• v.31 no.3
• /
• pp.281-289
• /
• 2022

Bio-CaCO₃ is a blowout environment-friendly materials for soil improvement and sealing of rock fissures. To evaluate the chemical characteristics, shape, size and productivity of soybean urease induced CaCO₃ precipitates (SUICP), experimental studies were conducted via EDS, XRD, FT-IR, TGA, BET, and SEM. Also, the conversion rate of SUICP reaction at different time were determined and analyzed. The Bio-CaCO₃ product obtained by SUICP is comprehensively judged as calcite based on the results of EDS, XRD and FT-IR. The SUICP calcite precipitates are detected as spherical or ellipsoidal particles 3-6 ㎛ in diameter with nanoscale pores on their surface, and this morphology is novel. The median secondary particle size d₅₀ is 39-88 ㎛, indicating the agglomeration of the primary calcite particles. The Bio-calcite decomposes at 650-780℃, representing a medium thermal stability. The conversion rate of SUICP reaction can reach 80% in 24h, which is much more efficient than microbially induced CaCO₃ precipitation. These results reveal the knowledges of SUICP, and further direct its engineering applications. Moreover, we show an economic channel to obtain porous spherical calcite.

• Applied Biological Chemistry
• /
• v.36 no.6
• /
• pp.510-516
• /
• 1993

The degradation and leaching pattern of benzoylurea insecticide teflubenzuron and flucycloxuron in soil environment and their effect on urease activity were investigated. The half-life of teflubenzuron was 39.1 days and 20.9 days in Chilgok and Ansim soil of nonsterilized condition, respectively, and that of flucycloxuron was 102.3 days and 50.1 days. Teflubenzuron and flucycloxuron were degraded more rapidly in Ansim soil with rich organic matter than Chilgok soil, and were degraded very slowly under sterilized condition. Their degradation seemed to be mainly mediated by microorganisms in soil. Teflubenzuron was degraded 63.2 days and 29.2 days faster than flucycloxuron under nonsterilized condition of Chilgok and Ansim soil. The inhibition of urease by the pesticides in two kinds of soil was strongly affected $(37.6{\sim}42.4%)$ in the early stage of their treatment but hardly affected or increased a little after 120 days. The teflubenzuron and flucycloxuron remained in the upper 5 cm of the soil column after elution with 1,000 ml of water, and they were not detected in leachate.

• Korean Journal of Microbiology
• /
• v.50 no.1
• /
• pp.60-66
• /
• 2014

This study was carried out to investigate the characteristics of FOST (fermented omija sugar treatment extracts) using Lactobacillus brevis HLJ59. Antioxidant activities of FOST were evaluated through viable cell number of L. brevis HLJ59, DPPH radical scavenging activity, reducing power and SOD-like activity, compared to non-FOST(non-fermented omija sugar treatment extracts). Also it was to evaluate Angiotensin Converting Enzyme (ACE) and Urease inhibitory activity of FOST. The viable cell number of L. brevis was about $2.05{\pm}0.21{\times}10^8$, $6.31{\pm}0.56{\times}10^{11}$, and $8.14{\pm}0.14{\times}10^9$ at ${\times}2$, ${\times}5$, and ${\times}10$ dilution, respectively. DPPH radical scavenging activity of FOST was about 60.3%, 71.8%, and 44.5% at ${\times}2$, ${\times}5$, and ${\times}10$ dilution, respectively. The reducing power of FOST was about 0.92, 1.19, and 0.73 (OD at 700 nm) at ${\times}2$, ${\times}5$, and ${\times}10$ dilution, and SOD-like activity of FOST was about 50.4%, 53.7%, and 33.4% at ${\times}2$, ${\times}5$, and ${\times}10$ dilution, respectively. ACE and Urease inhibitory activity by FOST was about 47.4%, 78.2%, 56.4% and 58.1%, 83.4%, 63.2% at ${\times}2$, ${\times}5$, and ${\times}10$ dilution, respectively. The results indicated that the fermentation of omija sugar treatment extracts using Lactobacillus brevis HLJ59 increased the antioxidant activities campared to the non-fermented omija sugar treatment extracts.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.18 no.4
• /
• pp.246-252
• /
• 2015

Purpose: To assess gastric pH and its relationship with urease-test positivity and histological findings in children with Helicobacter pylori infection. Methods: Fasting gastric juices and endoscopic antral biopsy specimens were collected from 562 children and subjected to the urease test and histopathological examination. The subjects were divided into 3 age groups: 0-4, 5-9, and 10-15 years. The histopathological grade was assessed using the Updated Sydney System, while the gastric juice pH was determined using a pH meter. Results: The median gastric juice pH did not differ significantly among the age groups (p=0.655). The proportion of individuals with gastric pH >4.0 was 1.3% in the 0-4 years group, 6.1% in the 5-9 years group, and 8.2% in 10-15 years (p=0.101). The proportions of moderate and severe chronic gastritis, active gastritis, and H. pylori infiltration increased with age (p<0.005). Urease-test positivity was higher in children with hypochlorhydria (77.8%) than in those with normal gastric pH (31.7%) (p<0.001). Chronic and active gastritis were more severe in the former than the latter (p<0.001), but the degree of H. pylori infiltration did not differ (20.9% vs. 38.9%; p=0.186). Conclusion: Gastric pH while fasting is normal in most children regardless of age. Urease-test positivity may be related to hypochlorhydria in children, and hypochlorhydria is in turn related to H. pylori infection.

• Korean Journal of Food Science and Technology
• /
• v.31 no.3
• /
• pp.764-770
• /
• 1999

Antimicrobial activities were assayed through the hot-water extracts from 41 species of medicinal plants against Helicobacter pylori which is known as the ulcerogenic phathogen. Opuntia ficus-indica, Houttuynia cordata, Sinomenium acutum, and Coptis japonica showed the MIC at the concentrations less than 100 ppm, Pulsatilla koreana, Forsythia koreana, Rheum undulatum, and Perilla frutescens less than 200 ppm, Belamcanda chinensis, Arctium lappa, Cassia tora, Citrus tachibana, Siegesbeckia orientalis, and Caesalpinia sappan less than 300 ppm by the 2-fold dilution method. In disc method only three of them were confirmed to have antimicrobial activities which were increased in the order Perilla frutescens, Coptis japonica, Caesalpinia sappan. Three extracts were partitioned with chloroform, ethyl acetate and butanol in sequence and examined for the activity to inhibit H. pylori. The major ativities were observed in ethyl acetate fraction of Caesalpinia sappan, butanol fraction of Perilla frutescens, butanol and chloroform fraction of Coptis japonica. The partitioned fractions were found to have increased antimicrobial activities in all extracts. The experiments in which the extracts were added into urea R broth containing the crude urease derived from H. pylori resulted in the increase of pH and optical density at 560 nm to 8.15 and 1.7 respectively. Urease activity of H. pylori was inhibited over 80% by Caesalpinia sappan, Perilla frutescens, and Coptis japonica, of which Caesalpinia sappan suppressed up to 95%.