Validity of rapid urease test using swab of gastric mucus to mucosal forceps and 13 C-urease breath test: a multicenter prospective observational study.

BACKGROUND: Theoretically, a rapid urease test (RUT) using a swab of the gastric wall (Swab-RUT) for Helicobacter pylori (H. pylori) is safe. However, the validity and utility of Swab-RUT remain unclear. Therefore, we assessed the validity and utility of Swab-RUT compared to RUT using mucosal forceps of the gastric wall (Forceps-RUT) and 13C-urea breath test (UBT). METHODS: This study was a multicenter prospective observational study. When the examinees were suspected of H. pylori infection during esophagogastroduodenoscopy, we performed Swab-RUT and Forceps-RUT continuously. When the examinees were not suspected of H. pylori infection, we performed Swab-RUT alone. We validated the status of H. pylori infection using UBT. RESULTS: Ninety-four examinees were enrolled from four institutions between May 2016 and December 2020 (median age [range], 56.5 [26-88] years). In this study, the sensitivity, specificity, and accuracy of Swab-RUT to UBT were 0.933 (95% confidence interval: 0.779-0.992), 0.922 (0.827-0.974), and 0.926 (0.853-0.970), respectively. The Kappa coefficient of Swab-RUT to UBT was 0.833, and that of Swab-RUT to forceps-RUT was 0.936. No complications were observed in this study. CONCLUSIONS: Swab-RUT is a valid examination for the status of H. pylori infection compared to the conventional Forceps-RUT.

Comparative diagnostic performance of rapid urease test with the sweeping method versus tissue sampling method after Helicobacter pylori eradication (with video).

BACKGROUND AND AIMS: The rapid urease test (RUT) is widely used to detect Helicobacter pylori infection; however, it is not preferred as a monitoring strategy after eradication owing to its low sensitivity. In this study, we evaluated the diagnostic performance of RUT using the sweeping method, which overcomes the limitations of conventional tissue sampling methods after eradication. METHODS: Patients who received H pylori eradication treatment were enrolled. Each of the sweeping and conventional methods was performed on the same patients to compare diagnostic performance. Urea breath test (UBT), histology, and polymerase chain reaction were performed to determine true infection. Logistic regression analysis was conducted to investigate reasons for discrepancies between the results of the 2 methods. RESULTS: In 216 patients, the eradication success rate was 68.1%, and the sensitivity and specificity of the sweeping method were 0.812 and 0.912, respectively, whereas those of the conventional method were 0.391 and 0.993, respectively (P < .05 for all). The area under the receiver operating characteristic curve for the sweeping method was higher than that for the conventional method (0.862 vs 0.692, P < .001). The mean time to H pylori detection for the sweeping method was 4.7 ± 4.4 minutes and 12.3 ± 16.1 minutes for the conventional method (P < .001). The risk for inconsistent results between the 2 methods was the highest for UBT values of 1.4‰ to 2.4‰ (odds ratio, 3.8; P = .016). CONCLUSIONS: The RUT with the sweeping method could potentially replace the tissue sampling method as a test to confirm H pylori eradication and be an alternative option to UBT for patients requiring endoscopy.

Infección por Helicobacter pylori y factores asociados en adultos de la sierra norte del Perú / Helicobacter pylori infection and associated factors in adults from the northern highlands of Peru

INTRODUCCIÓN: Helicobacter pylori afecta a más de 50% de la población mundial, siendo más prevalente en poblaciones de nivel socioeconómico bajo; esta bacteria constituye la principal causa de cáncer gástrico a nivel global. OBJETIVO: Determinar la frecuencia y los factores asociados a la infección por H. pylori en personas adultas que viven en el centro histórico de la ciudad de Cajamarca, en el norte del Perú. MATERIAL Y MÉTODO: Estudio descriptivo que incluyó 124 personas encuestadas mediante un cuestionario y evaluadas mediante endoscopía y cultivo de biopsia gástrica. Una biopsia por persona fue sometida a prueba de ureasa y los cultivos se confirmaron por reacción de polimerasa en cadena (RPC). RESULTADOS: La frecuencia de infección fue de 60,5 % (IC 95% 51,3 - 69,2). El análisis univariado demostró asociación significativa entre la infección y la edad (p = 0,002), y entre la infección y el antecedente de patología gástrica (p = 0,015). El análisis multivariado reveló dos factores asociados: edad (OR = 0,94; IC95% 0,90-0,97) y antecedente de infección por H. pylori (OR = 0,23; IC95% 0,08 - 0,67). CONCLUSIONES: Existe alta frecuencia de infección por H. pylori en esta población; la edad y el antecedente de infección constituyen factores asociados que deben evaluarse con mayor profundidad.

BACKGROUND: Helicobacter pylori affects more than 50% of the world's population, being more prevalent in populations of low socioeconomic status. H. pylori is the main cause of gastric cancer globally. AIM: To establish the frequency and factors associated with H. pylori infection in adults living in the historic center of Cajamarca City, in northern Peru. METHODS: This was a descriptive study that included 124 individuals surveyed through a questionnaire and evaluated through endoscopy and gastric biopsy culture. One biopsy per person underwent the urease test, and the cultures were confirmed by PCR. RESULTS: The frequency of infection was 60.5% (95% CI 51.3 - 69.2). In the univariate analysis, there was a significant association between the infection and age (p = 0.002), and between the infection and a history of gastric pathology (p = 0.015). The multivariate analysis revealed two associated factors: age (OR = 0.94; 95% CI 0.90 - 0.97), and history of H. pylori infection (OR = 0.23; 95% CI 0.08 - 0.67). CONCLUSIONS: There is a high frequency of H. pylori infection in this population, and the age and history of H. pylori infection are factors that should be further evaluated.

Detection of Helicobacter pylori Infection in Human Gastric Fluid Through Surface-Enhanced Raman Spectroscopy Coupled With Machine Learning Algorithms.

Diagnostic methods for Helicobacter pylori infection include, but are not limited to, urea breath test, serum antibody test, fecal antigen test, and rapid urease test. However, these methods suffer drawbacks such as low accuracy, high false-positive rate, complex operations, invasiveness, etc. Therefore, there is a need to develop simple, rapid, and noninvasive detection methods for H. pylori diagnosis. In this study, we propose a novel technique for accurately detecting H. pylori infection through machine learning analysis of surface-enhanced Raman scattering (SERS) spectra of gastric fluid samples that were noninvasively collected from human stomachs via the string test. One hundred participants were recruited to collect gastric fluid samples noninvasively. Therefore, 12,000 SERS spectra (n = 120 spectra/participant) were generated for building machine learning models evaluated by standard metrics in model performance assessment. According to the results, the Light Gradient Boosting Machine algorithm exhibited the best prediction capacity and time efficiency (accuracy = 99.54% and time = 2.61 seconds). Moreover, the Light Gradient Boosting Machine model was blindly tested on 2,000 SERS spectra collected from 100 participants with unknown H. pylori infection status, achieving a prediction accuracy of 82.15% compared with qPCR results. This novel technique is simple and rapid in diagnosing H. pylori infection, potentially complementing current H. pylori diagnostic methods.

A simple smartphone-assisted paper-based colorimetric biosensor for the detection of urea adulteration in milk based on an environment-friendly pH-sensitive nanocomposite.

Urea is a common milk adulterant that falsely increases its protein content. Excessive consumption of urea is harmful to the kidney, liver, and gastrointestinal system. The conventional methods for urea detection in milk are time-consuming, costly, and require highly skilled operators. So, there is an increasing demand for the development of rapid, convenient, and cost-efficient methods for the detection of urea adulteration in milk. Herein, we report a novel colorimetric paper-based urea biosensor, consisting of a novel environment-friendly nanocomposite of halloysite nanotubes (HNT), that urease enzyme and an anthocyanin-rich extract, as a natural pH indicator are simultaneously immobilized into its internal and external surfaces. The biosensing mechanism of this biosensor is based on anthocyanin color change, which occurs due to urease-mediated hydrolysis of urea and pH increment of the environment. The colorimetric signal of this biosensor is measured through smartphone-assisted analysis of the mean RGB (Red-Green-Blue) intensity of samples and is capable of detecting urea with a detection limit of 0.2 mM, and a linear range from 0.5 to 100 mM. This biosensor has demonstrated promising results for the detection of urea in milk samples, in the presence of other milk adulterants and interferents.

assessment of antioxidant, neuroprotective, anti-urease and anti-tyrosinase capacities of leaves extracts.

OBJECTIVE: To characterize the chemical profile of methanolic crude extract and its fractions (Ethyl acetate, n-butanol and aqueous) using liquid chromatography-mass spectrometry (LC-MS) analysis, to evaluate their biological and pharmacological properties: antioxidant (1, 1-diphenyl-2-pycrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic) (ABTS), galvinoxyle free radical scavenging, reducing power, phenanthroline and ß carotene-linoleic acid bleaching assays), enzymes inhibitory ability against several enzymes [acetyl-cholinesterase (AChE), buthyrylcholinesterase (BChE), urease and tyrosinase]. METHODS: Secondary metabolites were extracted from Tamarix africana air-dried powdered leaves by maceration, the crude extract was fractionated using different solvents with different polarities (Ethyl acetate, n-butanol and aqueous). The amount of polyphenols, flavonoids and tannins (hydrolysable and condensed) were determined using colorimetric assays. A variety of biochemical tests were carried out to assess antioxidant and oxygen radical scavenging properties using DPPH, ABTS, galvinoxyle free radical scavenging, reducing power, phenanthroline and ß carotene-linoleic acid bleaching methods. Neuroprotective effect was examined against acetylcholinesterase and buthy-rylcholinesterase enzymes. The anti-urease and anti-tyrosinase activities were performed against urease and tyrosinase enzymes respectively. The extract's components were identified using LC-MS and compared to reference substances. RESULTS: The results indicated that Tamarix africana extracts presented a powerful antioxidant activity in all assays and exhibited a potent inhibitory effect against AChE and BChE as well as urease and tyrosinase enzymes. LC-MS analysis identified amount of eight phenolic compounds were revealed in this analysis; Apigenin, Diosmin, Quercetin, Quercetine-3-glycoside, Apigenin 7-O glycoside, Rutin, Neohesperidin and Wogonin in methanolic extract and its different fractions of Tamarix africana from leaves. CONCLUSIONS: Based on these findings, it is reasonable to assume that Tamarix africana could be considered as a potential candidate for pharmaceutical, cosmetics, and food industries to create innovative health-promoting drugs.

Milk vetch returning reduces rice grain Cd concentration in paddy fields: Roles of iron plaque and soil reducing-bacteria.

Milk vetch (MV, Astragalus sinicus L.) is used in agricultural production as a green manure; however, its impact on accumulation levels of heavy metals (e.g., Cd) in rice remains poorly understood. This study investigated the effects of MV on Cd accumulation in rice, iron plaque formation, soil properties, and the soil microbial community structure through field experiments. The results showed that MV reduced Cd concentration in the roots, stem, leaves, and grains by 33%, 60%, 71%, and 49%, respectively. Chemical fertilizer and MV treatment promoted iron plaque formation, and MV considerably increased the Fe/Mn ratio in the iron plaque. More importantly, MV inhibited Cd transportation from the root iron plaque to the root by 74%. The concentrations of CaCl2-extractable Cd, available phosphorus, and available potassium, as well as the cation exchange capacity and urease activity, were significantly reduced in the MV treatment. Furthermore, 16 S rDNA high-throughput sequencing results of the soil microbial community structure showed that compared with the control, MV increased the soil microbial richness, increased the relative abundance of anaerobic microorganisms, and significantly increased the relative abundance of Thermodesulfovibrio and Geobacter at the genus level. The increase in anaerobic microbial abundance was closely related to the decrease in CaCl2-extractable Cd concentration. The application of MV promoted the formation of iron plaque, inhibited the transport of Cd, increased the abundance of anaerobic microorganisms, decreased the CaCl2-extractable Cd concentration, and reduced the Cd concentration in rice grain.

PRE-OPERATIVE SCREENING OF HELICOBACTER PYLORI IN BARIATRIC PATIENTS: IS HISTOPATHOLOGICAL ANALYSIS NECESSARY?

BACKGROUND: Helicobacter pylori infection has been reported to lead to post-operative complications after bariatric surgery (BS), especially marginal ulcers. The optimal method for pre-operative screening is yet to be determined. OBJECTIVE: To analyze the diagnostic accuracy of the endoscopic urease test for the detection of H. pylori in individuals undergoing BS and the main endoscopic and histological changes within this population. METHODS: A cross-sectional study was carried out based on a database from medical records of 232 individuals who underwent BS between 2016 and 2019 at a tertiary university hospital. Clinical, anthropometric, and endoscopic data were analyzed. The gold-standard method considered to calculate diagnostic accuracy variables was histopathological examination through hematoxylin-eosin/Giemsa stains. RESULTS: 87.5% of the participants were female; mean age was 38.5±9.5 years and average body mass index was 37.6±3.8 kg/m2. The commonest endoscopic finding was gastritis (50.9%) with a predominance of the mild erosive form (25%). Upon histological examination, 59.1% of the participants had confirmed H. pylori infection. H. pylori infection was associated with higher frequencies of endoscopic duodenitis (23.4% vs 12.6%; P=0.04), histological chronic gastritis (100% vs 56.8%; P<0.0001) and histological acute gastritis (58.4% vs 2.1%; P<0.0001). The urease test had a sensitivity of 79.6% and a specificity of 97.9%, leading to an overall accuracy of 87.1%. CONCLUSION: The endoscopic urease test is highly accurate for pre-operative screening of H. pylori infection in individuals who undergo BS. H. pylori infection was significantly associated with endoscopic (duodenitis) and histopathological (chronic and active gastritis) changes.

Isolation, Screening and Characterization of Ureolytic Bacteria from Cave Ornament.

<b>Background and Objective:</b> Ureolytic bacteria are bacteria capable of hydrolyzing urea. In construction, these bacteria are known to help improve soil stability. One of the habitats of ureolytic bacteria is cave ornaments such as gourdam, flowstone, stalagmite and stalactite. This study aims to find isolates and characterization of ureolytic bacteria in cave ornaments. <b>Materials and Methods:</b> Urea-CaCl₂ was used as the isolation medium and urea agar medium was used as a qualitative urease test for cave ornament bacteria isolate. This study applied a survey method and tested for gram staining, spore staining, mannitol test, catalase test and lactose test for characterization. <b>Results:</b> There were 17 isolates positive for urease from 30 isolates from the isolates of cave ornament bacteria. The characteristics of 17 ureolytic bacteria isolates were 2 isolates gram-negative basil with negative lactose test and 1 isolate positive glucose and 1 isolate negative glucose. Total 15 isolates gram-positive basil with spore staining results, 14 isolates spore-positive with 2 isolates positive mannitol and 12 isolates negative mannitol and 1 isolate spore-negative with negative catalase. <b>Conclusion:</b> Total 17 ureolytic bacteria isolates were found from cave ornaments. Biochemical characterization showed 1 isolate of <i>Proteus</i> spp., 1 isolate of <i>Pseudomonas</i> spp, 2 isolates suspected of being <i>Bacillus megaterium</i> or <i>Bacillus subtilis</i>, 12 isolates of <i>Bacillus cereus</i> and 1 isolate of <i>Lactobacillus</i> spp.

NQS-Doped PDMS Solid Sensor: From Water Matrix to Urine Enzymatic Application.

The development of in situ analytical devices has gained outstanding scientific interest. A solid sensing membrane composed of 1,2-naphthoquinone-4-sulfonate (NQS) derivatizing reagent embedded into a polymeric polydimethylsiloxane (PDMS) composite was proposed for in situ ammonium (NH4+) and urea (NH2CONH2) analysis in water and urine samples, respectively. Satisfactory strategies were also applied for urease-catalyzed hydrolysis of urea, either in solution or glass-supported urease immobilization. Using diffuse reflectance measurements combined with digital image processing of color intensity (RGB coordinates), qualitative and quantitative analyte detection was assessed after the colorimetric reaction took place inside the sensing membrane. A suitable linear relationship was found between the sensor response and analyte concentration, and the results were validated by a thymol-PDMS-based sensor based on the Berthelot reaction. The suggested sensing device offers advantages such as rapidity, versatility, portability, and employment of non-toxic reagents that facilitate in situ analysis in an energy-efficient manner.

Unacceptable Antibiotic Resistance Rates for Helicobacter pylori in Turkey: Something Must Change.

BACKGROUND: It is known that clarithromycin resistance has increased over the years (success rate 60%). The aim of the study was to investigate the importance of regional antimicrobial resistance rates for full accuracy of both diagnosis and treatment of Helicobacter pylori infection. METHODS: This study was carried out in the University Hospital Department of Gastroenterology. A total of 116 patients were evaluated with upper gastrointestinal endoscopy. Gastric antrum and corpus biopsy samples were taken for the rapid urease test (RUT), culture, and antimicrobial susceptibility testing for the presence of H. pylori. Antimicrobial susceptibilities of isolated H. pylori strains for clarithromycin and levofloxacin were determined by the epsilometer test (E-test). Minimal inhibitory concentration values for clarithromycin and levofloxacin were ≥1 and >1 µg/mL, respectively. RESULTS: H. pylori infection was considered clinically positive in 93 (80.2%) patients with either the RUT, culture, or histopathological examination. Seventy (60.3%) of the patients had RUT positivity. Sixty (85.7%) of these 70 patients had RUT positivity within the first 20 min. Among the 90 patients, who had a histopathological examination, HLO was positive in 76 (84.4%) patients. Fifty-two (44.8%) out of 116 patients were culture positive. Resistance rates for both clarithromycin and levofloxacin were high. In these 52 culture-positive patients, resistance rates determined for clarithromycin and levofloxacin were 26.9% and 25.5%, respectively. CONCLUSION: Clarithromycin or levofloxacin-based treatment regimen may not be an ideal alternative therapy for Turkish patients regardless of culture.

Acurácia diagnóstica entre teste rápido da urease e estudo histopatológico para detecção de Helicobacter pylori / Diagnostic accuracy of urease quick test compared to histopathological study for Helicobacter pylori detection

Objetivo: Analisar a acurácia do teste rápido da urease para detecção de Helicobacter pylori comparado com o exame histopatológico. Métodos: Estudo prospectivo e descritivo realizado de abril de 2018 a maio de 2019 em um Serviço de Endoscopia e Biliopancreática e em um laboratório de patologia. A amostra foi composta de 64 pacientes, de ambos os sexos, com idade de 35 a 81 anos, que apresentavam queixas dispépticas. Foram realizados exame histopatológico e teste rápido da urease. Os dados foram analisados pelo R Core team 2019 e submetidos a análises descritivas (variáveis categóricas) e inferenciais (teste de associação de qui-quadrado de Pearson e teste de Mann-Whitney). O nível de significância adotado foi de 5%. Resultados: O teste rápido da urease demonstrou que dez pacientes foram verdadeiros-positivos, 39 verdadeiros-negativos, três falsos-positivos, 12 falsos-negativos, com sensibilidade de 45,4% (25,1% a 67,3%), especificidade de 92,9% (79,4% a 98,1%), valor preditivo positivo de 76,9% (45,9% a 93,8%), valor preditivo negativo de 76,5% (62,2% a 86,7%), acurácia de 76,6% (64,0% a 85,9%), razão de chance diagnóstica 10,8 (2,56 a 45,9), índice de Youden 0,38 (0,16 a 0,60) e taxa de erro de 23,4% (14,1% a 36,0%). Conclusão: O teste rápido da urease apresentou baixa capacidade de detectar pacientes infectados, menor acurácia em relação ao estudo anatomopatológico e alta especificidade. O teste pode ser útil no momento da realização da endoscopia, por fornecer resultado rápido e barato para detectar H. pylori. O diagnóstico da bactéria apresenta maior confiabilidade com a realização dos dois métodos para pesquisa de H. pylori.

Objective: To analyze the accuracy of the rapid urease test for Helicobacter pylori detection when compared with the histopathological examination. Methods: This is a prospective and descriptive study conducted from April 2018 to May 2019, at an Endoscopy and Biliopancreatic Service and in a pathology laboratory. The sample consisted of 64 male and female patients aged 35 to 81 years old with dyspeptic complaints. Histopathological examination and rapid urease test were performed. Data were analyzed by R Corel team 2019 and underwent descriptive (categorical variables) and inferential (Pearson's Chi-squared association test and Mann-Whitney test) analyzes. The significance level adopted was 5%. Results: The rapid urease test showed that ten patients were true positive, 39 true negative, three false-positive, and 12 false-negative, and sensitivity was of 45.4% (25.1% to 67.3%), specificity 92.9% (79.4% to 98.1), positive predictive value of 76.9% (45.9-93.8%), negative predictive value of 76.5% (62.2% to 86.7%), accuracy of 76.6% (64.0% to 85.9%), diagnostic odds ratio of 10.8 (2.56% to 45.9), Youden index 0.38 (0.38% to 0.60), and error rate 23.4 (14.1% to 36.0%). Conclusion: The rapid urease test showed low ability to detect infected patients, lower accuracy compared to the pathological study, and high specificity. The test may be useful at the time of endoscopy, as it provides a quick and inexpensive result to detect H. pylori. The diagnosis of the bacterium is more reliable when both methods for H. pylori investigation are performed

Diagnostic accuracy of "sweeping" method compared to conventional sampling in rapid urease test for Helicobacter pylori detection in atrophic mucosa.

Although the rapid urease test (RUT) is a simple method for detecting Helicobacter pylori (H. pylori) infection, it requires sufficient biopsy samples and its sensitivity varies depending on the site and condition of H. pylori infection. We compared the diagnostic performance of a "sweeping method" for H. pylori detection with the conventional biopsy sampling method in atrophic gastric conditions which can reduce RUT accuracy. This prospective study included 279 patients who underwent upper endoscopy to determine the presence of H. pylori infection. Gastric mucosa of both the antrum and the corpus were swabbed, and we named this method the "sweeping method". Biopsy sampling for the conventional method, histologic evaluation, and polymerase chain reaction were performed at the same time. The sensitivity, specificity, and accuracy of the sweeping method were 0.941, 0.826, and 0.903, respectively, compared to 0.685, 0.859, and 0.742, respectively, for the conventional biopsy method. The area under the receiver operating curve for the sweeping method was 0.884 versus 0.772 for the conventional method (P < 0.001). The sweeping method had a faster detection time than the conventional method. Compared to conventional biopsy sampling, the sweeping method with the RUT provided higher sensitivity and accuracy for the detection of H. pylori, with a faster detection time.

Efficacy of fluopyram applied by chemigation on controlling eggplant root-knot nematodes (Meloidogyne spp.) and its effects on soil properties.

The root-knot nematode (Meloidogyne spp.) is one of the major challenges in eggplant (Solanum melongena L.) production. Fluopyram, known to be an effective fungicide, is also used for controlling root-knot nematode. However, in China, little information is currently available regarding the efficacy of fluopyram via chemigation against root-knot nematode and its effects on soil properties. For this, the objective of this work was to test mortality of root-knot nematode, functional diversity of soil microbial community, activity of soil enzyme after fluopyram applicated by chemigation. The results of two field experiments revealed that concentration of 60 g·ha-1 fluopyram applied with 200 L·ha-1 irrigation water at 2 L·h-1 flow velocity was the most effective chemigation parameters for controlling eggplant against root-knot nematode. The functional diversity of the soil microbial community was significantly affected by fluopyram. The activities of soil urease and ß-glucosidase decreased during the initial stages but recovered at later stages. In brief, fluopyram has advantageous for the efficient control of root-knot nematode with no deleterious effects on soil properties as well as chemigation is positive for application in karst landscape in Guangxi.

Would fertilization history render the soil microbial communities and their activities more resistant to rainfall fluctuations?

Water stress and nutrient supply are two of the most ubiquitous global changes that surely drive substantial variations not only in agricultural productivity but also extend to alert soil living organisms. The present study aims to understand the intrinsic changes in the composition of soil populations and their functions due to the interaction between long-term fertilization and rainfall fluctuations, seeing whether fertilization history would render the soil microbial communities and their activities more resistant to water stress or not. The experiment was established in 1988 on a typical meadow soil (Vertisols) as a rainfed maize monoculture receiving six elevated rates of NPK annually. The 30-year average annual precipitation of the growing season in this region is 345.1 mm. However, in 2010 rainfall was 106.1% greater than the average, while in 2011 it was 26.5% lower. The results show that long-term NPK fertilization has made the soil microbes more tolerant to changes in soil moisture content resulting from rainfall fluctuations. Soil microbes and their activities, however, did not follow a dose-response relationship of NPK as soil moisture content was the main driving factor. Numbers of total fungi, cellulose decomposing bacteria, and nitrifying bacteria increased as rainfall in 2010 increased. Moreover, microbial biomass carbon in 2010 was almost 2-fold higher than in 2009. Soil respiration in 2010 was 11 and 35% higher than in 2009 and 2011, respectively. Otherwise, high rainfall in 2010 significantly diminished soil NO3- content and nitrification rate. Soil enzyme activity showed a higher response to soil moisture than the rate of NPK. The highest activity of phosphatase, dehydrogenase, and saccharase was measured in the driest year (2011), while urease displayed its highest activity in 2010. High rates of NPK significantly reduced soil dehydrogenase activity. These results illustrate how important it is for fertilizer programs to be flexible to match expected climate change in order to improve productivity and reduce environmental pollution.

Droplet Digital PCR Detects Low-Density Infection in a Significant Proportion of Helicobacter Pylori-Negative Gastric Biopsies of Dyspeptic Patients.

INTRODUCTION: Helicobacter pylori-infected individuals may present low-density infection, undetectable by conventional tests such as histology, rapid urease test, or urea breath test. Droplet digital polymerase chain reaction (ddPCR) is more sensitive than other polymerase chain reaction methods. We aimed to evaluate the ability of ddPCR to detect H. pylori infection in patients diagnosed as negative by conventional tests. METHODS: Dyspeptic patients (n = 236) were tested for H. pylori by histology, urea breath test, and rapid urease test. Patients were classified as having 3 positive (n = 25, control group), 2 positive (n = 12), one positive (n = 41), or zero positive (n = 158) diagnostic tests. DNA was extracted from gastric biopsies. Triplicate ddPCR testing for each of the 16S rDNA, ureA, and vacA(s) genes was performed using a QX200 ddPCR system (Bio-Rad). A gene was considered positive when detected by at least 2 of 3 repeated ddPCRs. H. pylori positivity was defined as having 2 or more positive genes. RESULTS: All the biopsies of the control patients were positive for all 3 16S rDNA, ureA, and vacA(s) genes. H. pylori infection was detected in 57 (36%), 22 (54%), and 9 (75%) patients with zero, 1, and 2 positive diagnostic tests, respectively. The density of infection was 5, 121, 599, and 3,133 copies of H. pylori genome equivalents for patients with zero, 1, and 2 of 3 positive test results and for the control group, respectively. DISCUSSION: ddPCR detected low-density "occult" H. pylori infection in a significant proportion (36%) of patients diagnosed as negative by conventional methods. The number of conventional positive tests was related to the density of infection.

The responses of soil bacterial communities and enzyme activities to the edaphic properties of coal mining areas in Central China.

Soil physicochemical properties, bacterial communities and enzyme activities change with land subsidence resulting from coal mining. However, research on the responses of bacterial communities and enzyme activities to the soil properties in different degree of subsidence areas is limited. As such, we collected soil samples from a control area (C area), a moderate mining subsidence area (M area) and a severe mining subsidence area (S area) in Central China. Soil properties, such as the pH, total nitrogen (TN) content, total phosphorus (TP) content, available phosphorus (AP) content, organic matter (OM) content, and soil enzyme (urease, invertase, catalase and alkaline phosphatase) activities were measured in each sampling area at depths of 0-20 cm, 20-40 cm, and 40-60 cm. The results indicated that the soil physiochemical properties, soil urease activity, soil alkaline phosphatase activity and soil bacterial richness and diversity in the topsoil (0-20 cm) of the mining subsidence area were significantly lower than those in the C area. However, the soil enzyme activities within the deepest layer of the subsidence area were significantly greater than those of the C area. The bacterial communities within the depth of 0-20 cm were dominated by RB41, Pseudomonas, MND1, Nitrospira, Trichococcus, Sphingomonas and Dongia, whereas RB41 and Pseudomonas were the dominant species in the C area and subsidence area, respectively. Using correlation analysis, we found that the soil pH value, soil AP content and activities of the four enzymes were the main factors affecting the soil bacterial community structure. In addition, the soil nutrient contents, enzyme activities and bacterial richness and evenness decreased with increasing subsidence degree (classified by geological hazards, groundwater and landscape damage degree of coal mining subsidence). These results provide a reliable basis for environmental management of mining areas.

Effects of Sepiolite and Biochar on Enzyme Activity of Soil Contaminated by Cd and Atrazine.

The effects of sepiolite and biochar on the enzymatic activities of the soil in Cd- and atrazine-contaminated soils were studied. During the growth of pakchoi, the activities of acid phosphatase, sucrase, acid protease, and cellulase decreased, catalase activity increased, and urease activity decreased first and then increased. At the first harvest, compared with that for the control group, the soil pH after treatment with remediation materials increased from 5.41 to 7.43; the activities of urease, acid protease, and catalase increased by 62.8%, 38.6%, and 86.1%, respectively. And the activities of sucrase and acid phosphatase decreased by 17.3% and 24.7%, respectively. At the second harvest, the activities of acid phosphatase, acid protease, and cellulase continued to increase, but those of sucrase and catalase decreased. The results showed that soil enzyme activity was closely related to the type and addition of remediation materials, as well as the type of the enzyme.

Dose and time-dependent response of single and combined artificial contamination of sulfamethazine and copper on soil enzymatic activities.

The widespread contamination of antibiotics and heavy metals results in imbalance in the ecosystem. However, the effect of the interaction between sulfamethazine (SM2) and copper (Cu) on soil enzymatic activities is unclear. Therefore, this study investigated the effect of single and combined artificial contamination of SM2 and Cu (0, 1.6 mmol kg-1 Cu and 0, 0.05, 0.2, 0.8 mmol kg-1 SM2) on soil enzymatic activities (urease, sucrose, phosphatase, and RubisCO). A single application of Cu at a concentration of 1.6 mmol kg-1 inhibited the urease, phosphatase and sucrase activities, while a stimulating effect on RubisCO activity was observed on day 7, 21, and 28 of incubation. The individual application of SM2 at higher concentration exhibited significant inhibition of sucrase, phosphatase, and urease activities while a stimulatory effect on RubisCO activity was observed on day 14 and 21 of incubation. The combined contamination of SM2 and Cu significantly inhibited the activities of urease, sucrase, and phosphatase. The effect of combined contamination of SM2 and Cu on the activity of RubisCO was different. The analysis results of interaction types show that there are synergistic or antagonistic effects between Cu and SM2, and these effects can amplify or reduce the effect of Cu or SM2 on soil enzyme activities. Integrated biological responses version 2 (IBRv2) analysis showed that the combined contamination of Cu and SM2 had a greater inhibitory or stimulatory effect on soil enzyme activities than the single contamination of Cu and SM2, depending upon dose and time.