Removal of phenolic inhibitors from lignocellulose hydrolysates using laccases for the production of fuels and chemicals.

Lignocellulose is the most abundant biopolymer in the biosphere. It is inexpensive and therefore considered an attractive feedstock to produce biofuels and other biochemicals. Thermochemical and/or enzymatic pretreatment is used to release fermentable monomeric sugars. However, a variety of inhibitory by-products such as weak acids, furans, and phenolics that inhibit cell growth and fermentation are also released. Phenolic compounds are among the most toxic components in lignocellulosic hydrolysates and slurries derived from lignin decomposition, affecting overall fermentation processes and production yields and productivity. Ligninolytic enzymes have been shown to lower inhibitor concentrations in these hydrolysates, thereby enhancing their fermentability into valuable products. Among them, laccases, which are capable of oxidizing lignin and a variety of phenolic compounds in an environmentally benign manner, have been used for biomass delignification and detoxification of lignocellulose hydrolysates with promising results. This review discusses the state of the art of different enzymatic approaches to hydrolysate detoxification. In particular, laccases are used in separate or in situ detoxification steps, namely in free enzyme processes or immobilized by cell surface display technology to improve the efficiency of the fermentative process and consequently the production of second-generation biofuels and bio-based chemicals.

Early treatment with JNJ-46356479, a mGluR2 modulator, improves behavioral and neuropathological deficits in a postnatal ketamine mouse model of schizophrenia.

Positive allosteric modulators of the metabotropic glutamate receptor 2 (mGluR2), such as JNJ-46356479 (JNJ), may mitigate the glutamate storm during the early stages of schizophrenia (SZ), which could be especially useful in the treatment of cognitive and negative symptoms. We evaluated the efficacy of early treatment with JNJ or clozapine (CLZ) in reversing behavioral and neuropathological deficits induced in a postnatal ketamine (KET) mouse model of SZ. Mice exposed to KET (30 mg/kg) on postnatal days (PND) 7, 9, and 11 received JNJ or CLZ (10 mg/kg) daily in the adolescent period (PND 35-60). Mice exposed to KET did not show the expected preference for a novel object or for social novelty, but they recovered this preference with JNJ treatment. Similarly, KET group did not show the expected dishabituation in the fifth trial, but mice treated with JNJ or CLZ recovered an interest in the novel animal. Neuronal immunoreactivity also differed between treatment groups with mice exposed to KET showing a reduction in parvalbumin positive cells in the prefrontal cortex and decreased c-Fos expression in the hippocampus, which was normalized with the pharmacological treatment. JNJ-46356479 treatment in early stages may help improve the cognitive and negative symptoms, as well as certain neuropathological deficits, and may even obtain a better response than CLZ treatment. This may have relevant clinical translational applications since early treatment with mGluR2 modulators that inhibit glutamate release at the onset of critical phases of SZ may prevent or slow down the clinical deterioration of the disease.

Multi-element contamination in soils from major mining areas in Northeastern of Brazil.

Mining has become one of the main factors in the global biogeochemical cycle of potentially toxic elements. Therefore, it is considered one of the anthropogenic activities with the greatest negative impact on the environment. These impacts are maximized in semiarid regions, where mining activities can lead to soil degradation and decrease in land productivity. This study aimed to assess the level of contamination in natural, urban, and agricultural soils of three important mining areas, where approximately 80,000 people live, and pollution levels have never been determined before. For this purpose, soil samples were collected around iron, uranium, and vanadium mines, as well as in the main human settlements of the region. The concentrations of 34 elements were determined by instrumental neutron analysis activation (INAA) and inductively coupled plasma optical emission spectrometry (ICP OES) techniques. Pollution indices (CF, EF, mCd, PLI, and REEP) revealed that there is a moderate to heavy level of pollution for 89% of the analyzed elements. Additionally, an extreme contamination level was observed in 78% of the samples, for at least one element. Statistical analyses were performed to identify patterns in the distribution and common sources of pollution. The results suggest that the concentrations for Al, Ba, Hf, Na, Pb, Rb, REE, Ta, Th, U, Zn, and Zr are associated with geogenic causes. However, the influence of anthropogenic sources such as agriculture and mining on the accumulation of these elements in soils should not be disregarded. In contrast, the contents of As, Br, Cd, Co, Cr, Cs, Cu, Fe, K, Mn, Ni, Sc, Ti, and V reflect the direct impact of anthropogenic sources.

HHRISK: A code for assessment of human health risk due to environmental chemical pollution.

Chemical environmental pollution is currently one of the most concerning environmental problem on a global scale, due to the high risks posed to ecological systems and human health. Risk assessment methodologies are valuable tools for preventive management and the mitigation of human health risks. However, the application of these methodological tools involves several steps and the knowledge of many variables, which can hinder its correct implementation. The main objective of this work was the development of the computational code for human health risk assessment: HHRISK (Human Health Risk). This code allows for an agile and accurate risk assessment based on the methodology established by the U.S. Environmental Protection Agency (U.S. EPA). Different from other published methods, the HHRISK code includes a new spatiotemporal matrix for the analysis of the aggregated risk (for multiple exposure pathways) and the cumulative (for exposure to multiple chemicals). HHRISK was applied to two case studies published dealing with the assessment of risk to human health through exposure to toxic metals, obtaining satisfactory results. The concordance between the average results obtained with the HHRISK and those reported by the authors confirm the validity of the implemented model. The inclusion of a greater spatiotemporal detail of the risks allowed to carry out a more accurate analysis and to propose new subsidies for a more efficient risk mitigation management by affected place and period of time.

Bioaccumulation of nickel in tomato plants: risks to human health and agro-environmental impacts.

Anthropogenic activities such as agriculture, industry, and mining have contributed significantly to the accumulation of heavy metals in the soil, which in turn cause problems to human health and to the environment. The present work aims to study the effects of nickel (Ni) on the development of tomato plants, the risks to human health associated to the consumption of contaminated tomatoes, and the consequences to the environment. The experiment was carried out in greenhouse environment for a period of 120 days, and the plants were cultivated in soils with four different concentrations of Ni: 0, 35, 70, and 105 mg kg-1. The concentration of nickel in each part (root, stem, leaf, and fruit) of the tomato plant was measured at four different stages of the cycle: 30, 60, 90, and 120 days, by inductively coupled plasma optical emission spectrometer (ICP-OES). At the end of the cycle, the concentration of certain macro- and micronutrients was also determined and related to the corresponding Ni concentration in the soil. The distribution of Ni in the parts of the plant was analyzed from the bioaccumulation factor temporal behavior. Nickel concentrations found in the fruit were too low to pose a risk to human health. As a result of this research, it was verified that soils with nickel concentrations close to 70 mg kg-1, which is the limit established by the CONAMA resolution (420/2009), may actually represent an optimum concentration value for the development of tomato plants. It also increases productivity per plant and reduces the use of resources such as water and agricultural inputs.

Proteomic analysis of grapevine (Vitis vinifera L.) leaf changes induced by transition to autotrophy and exposure to high light irradiance.

Using a proteomics approach, we evaluated the response of heterotrophic and autotrophic leaves of grapevine when exposed to high light irradiation. From a total of 572 protein spots detected on two-dimensional gels, 143 spots showed significant variation caused by changes in the trophic state. High light treatment caused variation in 90 spots, and 51 spots showed variation caused by the interaction between both factors. Regarding the trophic state of the leaf, most of the proteins detected in the heterotrophic stage decreased in abundance when the leaf reached the autotrophic stage. Major differences induced by high light were detected in autotrophic leaves. In the high-light-treated autotrophic leaves several proteins involved in the oxidative stress response were up-regulated. This pattern was not observed in the high-light-treated heterotrophic leaves. This indicates that in these types of leaves other mechanisms different to the protein antioxidant system are acting to protect young leaves against the excess of light. This also suggests that these protective mechanisms rely on other sets of proteins or non-enzymatic molecules, or that differences in protein dynamics between the heterotrophic and autotrophic stages makes the autotrophic leaves more prone to the accumulation of oxidative stress response proteins. BIOLOGICAL SIGNIFICANCE: Transition from a heterotrophic to an autotrophic state is a key period during which the anatomical, physiological and molecular characteristics of a leaf are defined. In many aspects the right functioning of a leaf at its mature stage depends on the conditions under what this transition occurs. This because apart of the genetic control, environmental factors like mineral nutrition, temperature, water supply, light etc. are also important in its control. Many anatomical and physiological changes have been described in several plant species, however in grapevine molecular data regarding changes triggered by this transition or by light stress are still scarce. In this study, we identify that the transition from heterotrophic to autotrophic state in grapevine triggers major changes in the leaf proteome, which are mainly related to processes such as protein synthesis, protein folding and degradation, photosynthesis and chloroplast development. With the exception of proteins involved in carbon fixation, that increased in abundance, most of the proteins detected during the heterotrophic stage decreased in abundance when the leaf reached its autotrophic stage. This is most likely because leaves have reached their full size and from now they have to work as a carbon source for sink organs located in other parts of the plant. Despite the potential control of this transition by light, to date, no studies using a proteomics approach have been conducted to gain a broader view of the effects of short-term high light stress. Our results indicate that short-term high light exposure has a major impact on the proteome of the autotrophic leaves, and trigger a differential accumulation of several proteins involved in the oxidative stress response. Surprisingly, heterotrophic leaves do not display this pattern which can be attributed to a lower sensitivity of these leaves to high light stimulus. In fact we discovered that heterotrophic leaves are more tolerant to light stress than autotrophic leaves. This finding is of high biological significance because it helps to understand how young leaves are able to evolve to autotrophy in areas where high light intensities are predominant. This also reveals in this type of leaves the existence of alternative mechanisms to address this stressful condition. These observations provide new insights into the molecular changes occurring during transition of leaves to autotrophy particularly when this transition occurs under high light intensities. This for example occurs during the springtime when the grapevine buds burst and the young leaves are suddenly exposed to high light intensities.

Resultados a corto plazo del tratamiento con 131I en pacientes con bocio multinodular: influencia del grado de hipertiroidismo asociado y otras variables / Short-term results of treatment with 131I in patients with multinodular goiter: effect of the associated degree of hyperthyroidism and other variables

Objetivo. Evaluar la efectividad del tratamiento con radioyodo y la incidencia de hipotiroidismo posterior en pacientes con hipertiroidismo subclínico o hipertiroidismo clínico asociado a bocio multinodular (BMN). Métodos. Estudio retrospectivo de 69 pacientes consecutivos con BMN tratados con 131I, con una dosis fija ponderada de 16 mCi (592 MBq), durante el año 2008 y seguidos durante seis meses. Se clasificaron en dos grupos: hipertiroidismo subclínico e hipertiroidismo clínico. Comparamos la tasa de éxito y la incidencia de hipotiroidismo. Resultados. En el 82,09% de los pacientes se corrigió la disfunción tiroidea; entre los pacientes con hipertiroidismo clínico la proporción fue del 100% y con hipertiroidismo subclínico del 78,13% (p=0,105). La incidencia global de hipotiroidismo fue de 16,42%; 25,00% entre los que presentaban hipertiroidismo clínico y 14,55% entre los hipertiroidismos subclínicos (p=0,400). No se encontraron diferencias estadísticamente significativas al analizar los resultados según el grado de descenso de TSH en los pacientes con hipertiroidismo subclínico. Siete individuos presentaron anticuerpos antiperoxidasa tiroidea (anti-TPO) antes del tratamiento; la incidencia de hipotiroidismo fue superior en ellos (57,14% vs 11,67%; p=0,011). La prevalencia de arritmias cardiacas fue cuatro veces mayor en el grupo de hipertiroidismo clínico. El tratamiento previo con tiamazol afectó de manera positiva a los resultados. Conclusiones. Una dosis fija ponderada de 131I es altamente efectiva y segura para el control del hipertiroidismo clínico y subclínico asociado al BMN. Los pacientes con anticuerpos anti-TPO positivos parecen tener un elevado riesgo de desarrollar hipotiroidismo postyodo(AU)

Objective. To assess the effectiveness of radioactive iodine (RAI) therapy and the incidence of hypothyroidism post RAI in patients with subclinical hyperthyroidism or clinical hyperthyroidism with Multinodular Goiter (MNG). Methods. A retrospective study of 69 consecutive patients treated with 131I for MNG during the year 2008 observed for six months. All patients received a single fixed dose of 16 mCi (592 MBq) weighted by the gland size. They were categorized into two groups: subclinical hyperthyroidism or clinical hyperthyroidism. We compared the success rate and the incidence of hypothyroidism. Results. The thyroid dysfunction was corrected in 82.09% of the patients. Success rate was 100% in the clinical hyperthyroidism group and 78.13% in the subclinical hyperthyroidism group (P=0.105). The overall incidence of hypothyroidism was 16.42%; 25.00% of patients with clinical hyperthyroidism and 14.55% with subclinical hyperthyroidism developed this secondary effect (P=0.400). No statistically significant differences were found in the success rate in the incidence of hypothyroidism when the results were analyzed according to the thyrotropin decrease in patients with subclinical hyperthyroidism. Seven patients had positive anti-thyroid peroxidase antibodies (anti-TPO) before therapy. The incidence of hypothyroidism was significantly higher in them (57.14% vs 11.67%; P=0.011). Cardiac arrhythmias were four times more frequent in patients with clinical hyperthyroidism. Previous treatment with thiamazol positively affected the outcome. Conclusions. A single fixed weighted dose of 131I is highly effective and safe for the control of clinical and subclinical hyperthyroidism due to MNG. Patients with anti-TPO antibodies may have a high risk of developing post-iodine hypothyroidism(AU)

[Short-term results of treatment with 131I in patients with multinodular goiter: effect of the associated degree of hyperthyroidism and other variables]. / Resultados a corto plazo del tratamiento con 131I en pacientes con bocio multinodular: influencia del grado de hipertiroidismo asociado y otras variables.

OBJECTIVE: To assess the effectiveness of radioactive iodine (RAI) therapy and the incidence of hypothyroidism post RAI in patients with subclinical hyperthyroidism or clinical hyperthyroidism with Multinodular Goiter (MNG). METHODS: A retrospective study of 69 consecutive patients treated with (131)I for MNG during the year 2008 observed for six months. All patients received a single fixed dose of 16 mCi (592 MBq) weighted by the gland size. They were categorized into two groups: subclinical hyperthyroidism or clinical hyperthyroidism. We compared the success rate and the incidence of hypothyroidism. RESULTS: The thyroid dysfunction was corrected in 82.09% of the patients. Success rate was 100% in the clinical hyperthyroidism group and 78.13% in the subclinical hyperthyroidism group (P=0.105). The overall incidence of hypothyroidism was 16.42%; 25.00% of patients with clinical hyperthyroidism and 14.55% with subclinical hyperthyroidism developed this secondary effect (P=0.400). No statistically significant differences were found in the success rate in the incidence of hypothyroidism when the results were analyzed according to the thyrotropin decrease in patients with subclinical hyperthyroidism. Seven patients had positive anti-thyroid peroxidase antibodies (anti-TPO) before therapy. The incidence of hypothyroidism was significantly higher in them (57.14% vs 11.67%; P=0.011). Cardiac arrhythmias were four times more frequent in patients with clinical hyperthyroidism. Previous treatment with thiamazol positively affected the outcome. CONCLUSIONS: A single fixed weighted dose of (131)I is highly effective and safe for the control of clinical and subclinical hyperthyroidism due to MNG. Patients with anti-TPO antibodies may have a high risk of developing post-iodine hypothyroidism.

Sarcoidosis ósea. Hallazgos en la exploración con citrato de Galio / Sarcoidosis of bone. Findings in the Gallium citrate examination

Las lesiones óseas en la sarcoidosis son muy poco frecuentes y aparecen entre el 3–9% de los casos. Cuando se producen, son más frecuentes en los pequeños huesos de las manos y los pies que en los huesos largos, las vértebras o el cráneo. Presentamos el caso de un paciente con sarcoidosis con múltiples adenopatías y lesiones de la piel y óseas, así como los hallazgos gammagráficos(AU)

Sarcoidosis of bone lesions are rare, with an overall incidence of 3–9% of the cases. When they do occur, they are more frequent in the small bones of hands and feet than in long bones, spine or skull. We report a case of a male patient with sarcoidosis with multiple enlarged lymph nodes, skin and bone lesions, and the scintigraphic findings(AU)

[Sarcoidosis of bone. Findings in the Gallium citrate examination]. / Sarcoidosis ósea. Hallazgos en la exploración con citrato de Galio.

Sarcoidosis of bone lesions are rare, with an overall incidence of 3-9% of the cases. When they do occur, they are more frequent in the small bones of hands and feet than in long bones, spine or skull. We report a case of a male patient with sarcoidosis with multiple enlarged lymph nodes, skin and bone lesions, and the scintigraphic findings.

Proliferation and differentiation of human adipocyte precursor cells: differences between the preperitoneal and subcutaneous compartments.

Human adipocyte precursor cells (APC) have been characterized in their proliferation and differentiation potential from subcutaneous, omental, and mesenteric depots, mostly from morbidly obese patients. Cells from the preperitoneal adipose compartment have not been characterized yet, least of all when obtained from normal weight subjects. The aim was to compare proliferation and differentiation of subcutaneous (SC) and preperitoneal (PP) APC derived from adipose tissue in healthy subjects with different body mass. SC and PP adipose tissue was obtained during surgery of inguinal hernias in five healthy non-obese subjects and three obese otherwise healthy men. APC, obtained by collagenase digestion, were cultured. Proliferation was assayed by cell counting and differentiation by oil red O staining and flow cytometry using Nile Red staining. Proliferation of SC was higher than PP APC. Such differences between both compartments were even higher in APC obtained from obese patients. Conversely PP APC differentiated earlier in vitro compared with SC cells. These results agree with published data on fat cell proliferation. However regarding differentiation, our data show that APC from deeper depots (in this case PP) differentiate earlier than subcutaneous APC. This is different to previous studies performed in mesenteric or omental adipose tissue.

Intellectual capacity measurement in schizophrenia.

INTRODUCTION: The measurement of the intellectual capacity (IC) in schizophrenic patients has been found to be of clinical relevance. A user-friendly tool such as the Cattell's intelligence test might facilitate this measurement in daily clinical practice. METHOD: In this study, we measured the intelligence quotient (IQ) using Cattell's test in 35 schizophrenic patients before and after treatment with risperidone. RESULTS: At baseline, the sample showed an average intelligence of 78.3 points (standard deviation [SD]: 14.3), in the low-medium range. After 1 year on risperidone, the IQ significantly improved (mean: 84.8; SD: 17.0; p = 0.028). This IQ elevation was positively correlated with the improvement in the psychotic symptoms rated with the PANSS. CONCLUSIONS: Cattell's intelligence test could be a valid instrument to measure cognitive performance in schizophrenic patients. Antipsychotic therapy with risperidone could be effective to improve cognitive functioning in these subjects.

Medición de la capacidad intelectual en pacientes esquizofrénicos / Intellectual capacity measurement in schizophrenia

Introducción. La medición del conciente intelectual (CI) del paciente esquizofrénico resulta relevante para la intervención clínica con estos enfermos. Poder disponer de un instrumento de manejo sencillo como el test de inteligencia de Cattell permitiría realizar esta medición en la práctica clínica habitual. Método. En este estudio se presentan los hallazgos de la medición del nivel de CI en un grupo de 35 pacientes esquizofrénicos utilizando el test de Cattell antes y después del tratamiento con risperidona. Resultados. Al inicio del estudio se observó una inteligencia media de 78,3 puntos (desviación estándar [DE]: 14,3), que puede considerarse en el rango medio-bajo. Tras 1 año de tratamiento con risperidona se produjo una mejoría estadísticamente significativa del CI (media: 84,8; DE: 170; p=0,028). Esta elevación en el CI se correlacionó positivamente con la mejoría de la sintomatología psicótica medida mediante la PANSS. Conclusiones. El test de inteligencia de Cattell podría ser un instrumento válido para medir el rendimiento cognitivo de los pacientes esquizofrénicos. El tratamiento antipsicótico con risperidona podría ser efectivo para mejorar la función cognitiva en estos enfermos (AU)

Introduction. The measurement of the intellectual capacity (IC) in schizophrenic patients has been found to be of clinical relevance. A user-friendly tool such as the Cattell's intelligence test might facilitate this measurement in daily clinical practice. Method. In this study, we measured the intelligence quotient (IQ) using Cattell's test in 35 schizophrenic patients before and after treatment with risperidone. Results. At baseline, the sample showed an average intelligence of 78.3 points (standard desviation [SD]:14.3), in the low-medium range. After 1 year on risperidone, the IQ significantly improved (mean: 84.8; SD:17.0; p = 0.028). This IQ elevation was positively correlated with the improvement in the psychotic symptoms rated with the PANSS. Conclusions. Cattell's intelligence test could be a valid instrument to measure cognitive performance in schizophrenic patients. Antipsychotic therapy with risperidone could be effective to improve cognitive functioningin these subjects (AU)

Contrasting performances of generalist and specialist Myzus persicae (Hemiptera: Aphididae) reveal differential prevalence of maternal effects after host transfer.

Transgenerational maternal effects on performance (rm) after host transfer were evaluated in the generalist aphid Myzus persicae s.s., and in its subspecies specialized on tobacco, M. persicae nicotianae Blackman. We tested whether the performance of these taxa, when reared separately on optimal and suboptimal hosts (as sources of different maternal background) and then transferred to optimal hosts, experienced variations along four successive generations. Additionally, to compare the tolerance of both taxa to stress following host transfers, developmental instability (fluctuating asymmetry and body abnormalities) along the four generations was assessed. Taxon, rearing host, and generation affected the performance after host transfer. In the generalist, there was a significant improvement of rm along generations when transferred from suboptimal to optimal host and a significant decrease when transferred from optimal to optimal host; in the specialist, no increase or decrease occurred in any host transfer treatment. Transfer from suboptimal to optimal hosts caused higher losses of remaining replicates along generations than transfers from optimal to optimal hosts, and the specialist showed higher losses than the generalist. The only significant effect detected in comparisons involving fluctuating asymmetry values was that of taxon on length of siphunculi. Frequency of body abnormalities was not affected by treatments. Collectively, these results show a transgenerational weakening of maternal effects in the generalist but not in the specialist aphid, and suggest that rearing the latter in a suboptimal host causes not easily reversible changes that further give rise to constraints in performance.

Factores implicados en la patogenia de la infección por Helicobacter pylori / Factors involved in the pathogenesis of Helicobacter pylori infection

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Recurrence of Helicobacter pylori infection after several eradication therapies: long-term follow-up of 1000 patients.

AIM: To study the incidence of Helicobacter pylori recurrence, its chronological aspects, and the variables that might influence it. METHODS: A total of 1000 patients in whom H. pylori had been eradicated were prospectively studied. Therapies were classified as low and high efficacy regimens. Four to eight weeks after completion of therapy, 13C-urea-breath-test was performed, and it was repeated yearly up to 5 years. In some patients, endoscopy with biopsies was also performed to confirm H. pylori eradication. RESULTS: A total of 1000 patients were included, giving 2744 patient-years of follow-up. Seventy-one H. pylori recurrences were observed (2.6% per patient-year). Probability of being H. pylori-negative at 1 year was 94.7%, and at 5 years 90.7%. In the multivariate analysis, low age (OR: 1.84; 95% CI: 1.04-3.26) and low efficacy therapies (OR: 2.5; 1.23-5.04) correlated with 1-year H. pylori recurrence. Differences were observed when Kaplan-Meier curves were compared depending on age and therapy regimen. CONCLUSION: Risk of posteradication H. pylori recurrence is higher during the first year, which suggests that most recurrences during this period are recrudescence and not true reinfections. H. pylori recurrence is more frequent in younger patients and in those treated with low efficacy therapies, but is exceptional if high efficacy therapies are used, in which case post-therapy eradication can be safely confirmed at 4 weeks with 13C-urea-breath-test.

Long-term follow-up of 13C-urea breath test results after Helicobacter pylori eradication: frequency and significance of borderline delta13CO2 values.

BACKGROUND: The precise choice of cut-off point for the 13C-urea breath test to define whether it is positive or negative represents a controversial issue. AIM: To quantify the 13C-urea breath test result for several years following Helicobacter pylori eradication, and to evaluate the frequency and the significance of borderline delta13CO2 values. METHODS: Two-hundred H. pylori eradicated patients confirmed by 13C-urea breath test (100 mg of urea, citric acid), and having had repeated this test yearly up to 5 years, were studied. Delta13CO2 values between 2 and 5/1000 were considered as borderline results. RESULTS: Eight H. pylori recurrences were observed during 406 patient-years of follow-up (1.97% yearly). In two of eight reinfected patients, the reinfection was preceded by a negative delta13CO2 value >2/1000. Borderline delta13CO2 values were detected in 4% of the 606 urea breath tests performed, and in 25% when only patients in whom H. pylori recurrence was detected in subsequent urea breath tests were included (P < 0.05). The negative-predictive value of a post-treatment delta13CO2 >2/1000 for the diagnosis of H. pylori recurrence was 99%. CONCLUSIONS: Positive and negative urea breath test results tend to cluster outside the range between 2/1000 and 5/1000. Nevertheless, a borderline urea breath test delta value (e.g. very close to the selected cut-off point) should be interpreted cautiously, and the result should probably be confirmed either by repeating the urea breath test or by other diagnostic methods. On the contrary, a delta13CO2 value <2/1000 very confidently confirms H. pylori eradication.