Mechanochemical Enhancement of the Structural Stability of Pseudorotaxane Intermediates in the Synthesis of Rotaxanes.

Mechanochemical syntheses of rotaxanes have attracted considerable attention of late because of the superior reaction rates and higher yields associated with their production compared with analogous reactions carried out in solution. Previous investigators, however, have focused on the demonstration of the mechanochemical syntheses of rotaxanes per se, rather than on studying the solid-phase host-guest molecular interplay related to their rapid formation and high yields. In this investigation, we attribute the lower yields of rotaxanes prepared in solution to the limited concentration and a desolvation energy penalty that must be compensated for by host-guest interactions during complexation that precedes the templation leading to rotaxane formation. It follows that, if the desolvation energy can be removed and higher concentrations can be attained, even weak host-guest interactions can drive the complexation of host and guest molecules efficiently. In order to test this hypothesis, we chose two host-guest pairs of permethylated pillar[5]arene/1,6-diaminohexane and permethylated pillar[5]arene/2,2'-(ethylenedioxy)bis(ethylamine) for the simple reason that they exhibit extremely low binding constants (2.7 ± 0.4 M-1 when 1,6-diaminohexane is the guest and <0.1 M-1 when 2,2'-(ethylenedioxy)bis(ethylamine) is the guest in CDCl3; i.e., ostensibly no pseudorotaxane formation is observed). We argue that the amount of pseudorotaxanes formed in the solid state is responsive to mechanical treatments or otherwise and changes in temperature during stoppering reactions. Compared to the amount of pseudorotaxanes that can be obtained in solution, large quantities of pseudorotaxanes are formed in the solid state because of concentration and desolvation effects. This mechanochemical enhancement of pseudorotaxane formation is referred to as a self-correction in the current investigation. Rotaxanes based on permethylated pillar[5]arene/1,6-diaminohexane and permethylated pillar[5]arene/2,2'-(ethylenedioxy)bis(ethylamine) have been synthesized in much higher yields compared to those obtained in solution, aided and abetted by self-correction effects during mechanical treatments and heating at a mild temperature of 50 °C.

Redox-Active Phenanthrenequinone Triangles in Aqueous Rechargeable Zinc Batteries.

Aqueous rechargeable zinc batteries (ZBs) have received considerable attention recently for large-scale energy storage systems in terms of rate performance, cost, and safety. Nevertheless, these ZBs still remain a subject for investigation, as researchers search for cathode materials enabling high performance. Among the various candidate cathode materials for ZBs, quinone compounds stand out as candidates because of their high specific capacity, sustainability, and low cost. Quinone-based cathodes, however, suffer from the critical limitation of undergoing dissolution during battery cycling, leading to a deterioration in battery life. To address this problem, we have introduced a redox-active triangular phenanthrenequinone-based macrocycle (PQ-Δ) with a rigid geometry and layered superstructure. Notably, we have confirmed that Zn2+ ions, together with H2O molecules, can be inserted into the PQ-Δ organic cathode, and, as a consequence, the interfacial resistance between the cathode and electrolytes is decreased effectively. Density functional theory calculations have revealed that the low interfacial resistance can be attributed mainly to decreasing the desolvation energy penalty as a result of the insertion of hydrated Zn2+ ions in the PQ-Δ cathode. The combined effects of the insertion of hydrated Zn2+ ions and the robust triangular structure of PQ-Δ serve to achieve a large reversible capacity of 210 mAh g-1 at a high current density of 150 mA g-1, along with an excellent cycle-life, that is, 99.9% retention after 500 cycles. These findings suggest that the utilization of electron-active organic macrocycles, combined with the low interfacial resistance associated with the solvation of divalent carrier ions, is essential for the overall performance of divalent battery systems.

The High Performance of Crystal Water Containing Manganese Birnessite Cathodes for Magnesium Batteries.

Rechargeable magnesium batteries have lately received great attention for large-scale energy storage systems due to their high volumetric capacities, low materials cost, and safe characteristic. However, the bivalency of Mg(2+) ions has made it challenging to find cathode materials operating at high voltages with decent (de)intercalation kinetics. In an effort to overcome this challenge, we adopt an unconventional approach of engaging crystal water in the layered structure of Birnessite MnO2 because the crystal water can effectively screen electrostatic interactions between Mg(2+) ions and the host anions. The crucial role of the crystal water was revealed by directly visualizing its presence and dynamic rearrangement using scanning transmission electron microscopy (STEM). Moreover, the importance of lowering desolvation energy penalty at the cathode-electrolyte interface was elucidated by working with water containing nonaqueous electrolytes. In aqueous electrolytes, the decreased interfacial energy penalty by hydration of Mg(2+) allows Birnessite MnO2 to achieve a large reversible capacity (231.1 mAh g(-1)) at high operating voltage (2.8 V vs Mg/Mg(2+)) with excellent cycle life (62.5% retention after 10000 cycles), unveiling the importance of effective charge shielding in the host and facile Mg(2+) ions transfer through the cathode's interface.

Direct Observation of an Anomalous Spinel-to-Layered Phase Transition Mediated by Crystal Water Intercalation.

The phase transition of layered manganese oxides to spinel phases is a well-known phenomenon in rechargeable batteries and is the main origin of the capacity fading in these materials. This spontaneous phase transition is associated with the intrinsic properties of manganese, such as its size, preferred crystal positions, and reaction characteristics, and it is therefore very difficult to avoid. The introduction of crystal water by an electrochemical process enables the inverse phase transition from spinel to a layered Birnessite structure. Scanning transmission electron microscopy can be used to directly visualize the rearrangement of lattice atoms, the simultaneous insertion of crystal water, the formation of a transient structure at the phase boundary, and layer-by-layer progression of the phase transition from the edge. This research indicates that crystal water intercalation can reverse phase transformation with thermodynamically favored directionality.

Effect of Crown Ether Additives on the Enhanced Performance of Metallic Bipolar Plates for Proton Exchange Membrane Fuel Cells.

One of the key components of the fuel cell stack is a metallic bipolar plate (MBP) that plays multiple roles, such as current collector, fuel and oxidant distributor, and mechanical support. However, corrosion and consequent metal elution are major drawbacks of the MBP because they diminish the efficiency and power performance of membrane-electrode assemblies (MEAs). Herein, we show that the crown ether (CE) additive can simultaneously inhibit surface corrosion of the MBP and act as a scavenger for eluted metal ions to alleviate contamination of other components. From the electrochemical measurement, high-resolution imaging, and elemental analysis, we have found that the CE undergoes electrolytic decomposition and makes an efficient protective layer in an in situ manner. This layer prevents direct contact between the MBP and electrolyte as well as the dissolution of metal ions into the electrolyte. In addition, we demonstrate that the CE can improve the recovery protocol of the MEA owing to the formation of host-guest complexes between the CE and metal cations. These results provide key insights into the design of high-performance MBPs for proton-exchange membrane fuel cells.

Chelating Effects of Polyphenolic Biomolecules to Improve ß-MnO2 Cathode Performance for Aqueous Rechargeable Zinc-Ion Batteries.

Aqueous rechargeable zinc-ion batteries (ARZBs) are promising energy storage systems (ESSs) due to lots of advantages, such as high safety, high capacity, abundant resources, and low cost. However, the tunnel-structured Mn-based cathode materials such as α, ß, and γ-MnO2, which is widely used as the cathode of ARZBs, contain a phase transition in which Mn2+ ions are eluted during the discharge reaction of Zn2+ insertion, resulting in decreasing cycle life and rate capability of the ARZBs. Here, in order to enhance the cycle life and rate capability of ARZBs by retaining eluted Mn2+ ions around the ß-MnO2 cathode during the discharge process, tannic acid (TA), a type of polyphenolic biomolecule containing rich -OH groups, is introduced as a coating material. This provides a chelating effect with the eluted Mn2+ ions and hydroxyl groups on the surface of the ß-MnO2 cathode. This study clearly shows that the TA coating improves the performance of the cathode material by using a range of analytical methods. Owing to the chelating effects of TA, TA-coated ß-MnO2 cathode shows a high discharge capacity of 268.2 mAh g-1 at the current of 100 mA g-1 and 86.8% of high capacity retention after 50 cycles. This study provides the coating agents with chelating effects to develop Zn//MnO2 battery chemistry and further improve large ESSs through high electrochemical performance.

Chelated Metal-Organic Frameworks for Improved the Performance of High-Nickel Cathodes in Lithium-Ion Batteries.

Lithium-ion batteries have gained widespread use in various applications, including portable devices, electric vehicles, and energy storage systems. High Ni cathode, LiNixCoyMnzO2 (NCM, x ≥ 0.8, x + y + z = 1), have garnered significant attention owing to their high energy density. However, the limited lithium-ion transfer rate and transition metal cross-talk to anode pose obstacles to further improvement of electrochemical performance. To tackle these challenges, metal-organic frameworks (MOFs) with chelating agents are employed as additive materials for electrode. MOFs with chelating agents offer three key attributes: (1) Effective mitigation of transition metal cross-talk to the anode, (2) Partial desolvation of Li+ ions through MOF pores, and (3) Immobilization of anions via metal sites in the MOF. Leveraging these advantages, the chelating MOF-modified NCM cathode demonstrates reduced charge transfer resistance, both in their pristine and cycled states. In addition, they exhibit significantly improved lithium-ion diffusion coefficients after 100 cycles. These findings underscore the potential of MOFs with chelating agents as promising additive materials for enhancing the performance of LIBs.

Metal-organic frameworks for high-performance cathodes in batteries.

Metal-organic frameworks (MOFs) are functional materials that are proving to be indispensable for the development of next-generation batteries. The porosity, crystallinity, and abundance of active sites in MOFs, which can be tuned by selecting the appropriate transition metal/organic linker combination, enable MOFs to meet the performance requirements for cathode materials in batteries. Recent studies on the use of MOFs in cathodes have verified their high durability, cyclability, and capacity thus demonstrating the huge potential of MOFs as high-performance cathode materials. However, to keep pace with the rapid growth of the battery industry, several challenges hindering the development of MOF-based cathode materials need to be overcome. This review analyzes current applications of MOFs to commercially available lithium-ion batteries as well as advanced batteries still in the research stage. This review provides a comprehensive outlook on the progress and potential of MOF cathodes in meeting the performance requirements of the future battery industry.

Supramolecular Metal-Organic Framework for the High Stability of Aqueous Rechargeable Zinc Batteries.

Aqueous rechargeable Zn batteries (AZBs) are considered to be promising next-generation battery systems. However, the growth of Zn dendrites and water-induced side reactions have hindered their practical application, especially with regard to long-term cyclability. To address these challenges, we introduce a supramolecular metal-organic framework (SMOF) coating layer using an α-cyclodextrin-based MOF (α-CD-MOF-K) and a polymeric binder. The plate-like α-CD-MOF-K particles, combined with the polymeric binder create dense and homogeneous Zn2+ ion conductive pore channels that can vertically transport Zn2+ ions through the cavity while restricting the contact of water molecules. Molecular dynamics (MD) simulation verifies that Zn2+ ions can reversibly migrate through the pores of α-CD-MOF-K by partial dehydration. The uniform Zn deposition/dissolution promotes a smooth solid-electrolyte interface layer on the Zn metal anode and effectively suppresses side reactions with free water molecules. The α-CD-MOF-K@Zn symmetric cell exhibits stable cycling and a small polarization voltage of 70 mV for 800 h at 5 mA cm-2, and the α-CD-MOF-K@Zn|α-MnO2 full cell shows only 0.12% capacity decay per cycle at a rate of 1 A g-1.

Advances in Polymer Binder Materials for Lithium-Ion Battery Electrodes and Separators.

Lithium-ion batteries (LIBs) have become indispensable energy-storage devices for various applications, ranging from portable electronics to electric vehicles and renewable energy systems. The performance and reliability of LIBs depend on several key components, including the electrodes, separators, and electrolytes. Among these, the choice of binder materials for the electrodes plays a critical role in determining the overall performance and durability of LIBs. This review introduces polymer binders that have been traditionally used in the cathode, anode, and separator materials of LIBs. Furthermore, it explores the problems identified in traditional polymer binders and examines the research trends in next-generation polymer binder materials for lithium-ion batteries as alternatives. To date, the widespread use of N-methyl-2-pyrrolidone (NMP) as a solvent in lithium battery electrode production has been a standard practice. However, recent concerns regarding its high toxicity have prompted increased environmental scrutiny and the imposition of strict chemical regulations. As a result, there is a growing urgency to explore alternatives that are both environmentally benign and safer for use in battery manufacturing. This pressing need is further underscored by the rising demand for diverse binder research within the lithium battery industry. In light of the current emphasis on sustainability and environmental responsibility, it is imperative to investigate a range of binder options that can align with the evolving landscape of green and eco-conscious battery production. In this review paper, we introduce various binder options that can align with the evolving landscape of environmentally friendly and sustainable battery production, considering the current emphasis on battery performance enhancement and environmental responsibility.

Diagnostic value of the PPI test for detection of GERD in Korean patients and factors associated with PPI responsiveness.

OBJECTIVES: Data supporting the use of the proton pump inhibitor (PPI) test as a diagnostic test of gastroesophageal reflux disease (GERD) in Asia are lacking. The aims of this study were to evaluate the diagnostic characteristics of the PPI test and factors associated with responsiveness to PPIs. METHODS: The PPI test was evaluated using lansoprazole (30 mg bid) for two weeks. All patients underwent endoscopy after symptom assessment. Patients without erosive esophagitis (ERD) underwent 48 h esophageal Bravo pH monitoring. Subjects were considered to be responsive to PPIs if they reported a > 50% reduction in reflux symptom score. RESULTS: Seventy-three patients (M:F = 40:37, 47 +/- 13 years) were enrolled. We identified 46 patients with ERD, 18 patients with nonerosive reflux disease (NERD) and 9 patients without GERD. The PPI response rate was higher in patients with GERD than in patients without GERD (49/64, 77% vs. 4/9, 44%; p < 0.05). The sensitivity, specificity, and positive and negative predictive values were 77%, 56%, 92% and 25%, respectively. The PPI responsiveness was 80% (37/46) in the ERD group and 67% (12/18) in the NERD group. PPI response was not affected by age, sex, Helicobacter pylori, the psychological characteristics or cytochrome P2C genotypes. ERD and symptom-reflux association were the factors affecting PPI responsiveness. CONCLUSIONS: The PPI test was modestly sensitive and specific for diagnosing GERD. However, it would be useful for discriminating patients with ERD. In the NERD group, patients with positive symptom-reflux association would be most benefit from PPI treatment.

Clinical outcomes of self-expandable metal stent and prognostic factors for stent patency in gastric outlet obstruction caused by gastric cancer.

The aim of this study was to assess clinical outcomes of endoscopic stenting for a gastric outlet obstruction caused by gastric cancer and the prognostic factors for stent patency by reviewing medical records. Eighty-one stents were inserted into 75 patients (48 men, average age 66 years). The technical and clinical success rates were 98 and 87%, respectively. The median stent patency was 55 days (95% CI 40-70 days). The median survival was 79 days (95% CI 58-123 days). Stent reobstruction caused by tumor ingrowth or overgrowth occurred in 25 cases (31%). Cox multivariate regression analysis showed that covered stents (odds ratio 0.29, 95% CI 0.11-0.76; P = 0.01) and chemotherapy after stent placement (odds ratio 0.34, 95% CI 0.13-0.91; P = 0.03) were significant prognostic factors for stent patency. This study found that endoscopic stenting is a safe and effective palliation treatment for malignant gastric outlet obstruction and a covered stent and chemotherapy are significant prognostic factors for stent patency.

[Change of Clostridium difficile colitis during recent 10 years in Korea].

BACKGROUND/AIMS: Our clinical experience and recent published literatures suggest that Clostridium difficile colitis (CDC) has become more common and potentially more pathogenic in recent years. The aim of study was to evaluate changes in the epidemiological features of CDC in hospitalized patients in Korea. METHODS: We retrospectively reviewed all patients of CDC diagnosed at Kangnam St. Mary Hospital from 1998 to 2007. CDC was defined as having a positive C. difficile cytotoxicity assay, or endoscopic or pathologic evidence of CDC. RESULTS: A total of 189 cases (male 73, female 116, mean age 63.3 years) of CDC were diagnosed during the study period. The prevalence of CDC increased from 1.9/10,000 patient admissions in 1998-1999 to 8.82/10,000 patient admissions in 2006-2007. One hundred sixty three indication for cases (86.2%) of patients identified a prior use of antibiotics in the 2 months preceding diagnosis. The most common antibiotic use was prophylactic use during perioperational period (33.3%) followed by pneumonia (23.3%). The overall response rate to initial antibiotics was 82.7%. One hundred seventy two (91%) patients were initially treated with metronidazole. The response rate was 84.3%. All patients with initial failure to metronidazole were successfully treated by vancomycin. The response rate of vancomycin as first treatment was 80%. Three deaths were associated with CDC despite the use of combination of metronidazole and vancomycin. CONCLUSIONS: The prevalence of CDC in hospitalized patients in Korea significantly increased from 1998 to 2007.

Conductive 2D metal-organic framework for high-performance cathodes in aqueous rechargeable zinc batteries.

Currently, there is considerable interest in developing advanced rechargeable batteries that boast efficient distribution of electricity and economic feasibility for use in large-scale energy storage systems. Rechargeable aqueous zinc batteries are promising alternatives to lithium-ion batteries in terms of rate performance, cost, and safety. In this investigation, we employ Cu3(HHTP)2, a two-dimensional (2D) conductive metal-organic framework (MOF) with large one-dimensional channels, as a zinc battery cathode. Owing to its unique structure, hydrated Zn2+ ions which are inserted directly into the host structure, Cu3(HHTP)2, allow high diffusion rate and low interfacial resistance which enable the Cu3(HHTP)2 cathode to follow the intercalation pseudocapacitance mechanism. Cu3(HHTP)2 exhibits a high reversible capacity of 228 mAh g-1 at 50 mA g-1. At a high current density of 4000 mA g-1 (~18 C), 75.0% of the initial capacity is maintained after 500 cycles. These results provide key insights into high-performance, 2D conductive MOF designs for battery electrodes.

[Relationship between pepsinogen I/II ratio and age or upper gastrointestinal diseases in Helicobacter pylori-positive and -negative subjects].

BACKGROUND/AIMS: Although previous reports suggested that pepsinogen (PG) I/II ratio was the index of gastric atrophy, PG I/II ratio was also related to other factors such as Helicobacter pylori (H. pylori) infection, various gastrointestinal diseases, and aging. The aim of this study was to evaluate the relationship between serum PG I/II ratio and age or upper gastro-intestinal diseases according to H. pylori infection status. METHODS: A total of 529 individuals (307 male; mean age, 57.2 years) were divided into 4 groups (94 gastric ulcers, 35 duodenal ulcers, 105 reflux esophagitis, and 295 atrophic gastritis) according to endoscopic diagnosis. H. pylori infection was determined by H. pylori IgG antibody (ELISA) and PG was measured by latex immunoassay. RESULTS: H. pylori infected patients showed markedly increased serum PG II levels (24.0+/-14.7 ng/mL vs. 13.8+/-16.6 ng/mL, p0.001) and low PG I/II ratio (3.9+/-2.0 vs. 6.0+/-2.5, p0.001) than non-infected subjects. In H. pylori infected patients, mean PG I/II ratios in the gastric ulcer and atrophic gastritis group were significantly lower than those of the duodenal ulcer and reflux esophagitis group (p0.001, ANOVA, Turkey's multiples comparison test). The mean ratio of open type atrophic gastritis was lower than that of close type atrophic gastritis (3.0+/-1.4 vs. 3.8+/-1.7, p0.005). PG I/II ratio gradually decreased with age in H. pylori-infected patients with atrophic gastritis (R(2)=0.9, p=0.005, linear regression analysis). CONCLUSION: Serum PG I/II ratio reflects H. pylori infection and gastric atrophy. In the presence of H. pylori infection, gastric atrophy progresses with age.

[Docetaxel-cisplatin-5-FU combination chemotherapy as a first-line treatment in patients with metastatic or recurred gastric cancer].

BACKGROUND/AIMS: The purpose of this study was to investigate the efficacy and safety of 'docetaxel-5-FU-cisplatin' combination chemotherapy as a first-line treatment in patients with metastatic or recurrent gastric cancer. METHODS: We investigated a total of 51 patients who were diagnosed as pathologically proven gastric cancer and received 'docetaxel-5-FU-cisplatin' combination chemotherapy between March 2001 and March 2006. All the cases were surgically unresectable because they were either metastatic or recurred gastric cancer. We studied these cases retrospectively on the basis of medical records. The administered doses of decetaxel was 75 mg/m2 and cisplatin 60 mg/m2 on day 1, 5-FU 750 mg/m2 over 24 hrs on day 1 to day 5, every 4 weeks. RESULTS: Among the 51 patients, 21 patients had Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0, 27 patients had PS 1, 3 patients had PS 2. For response rates, 7 (13.7%) achieved complete response, 17 (33.3%) partial response, 12 (23.5%) stable disease, and 15 (29.4%) progressive disease, respectively. The overall response rate was 47.1%. The median time to progression was 6.7 months (2-34 months). Median overall survival was 14.6 months (2.7-62.5 months). Median disease free survival was 9.5 months (4.2-21.9 months). National Cancer Institute-common toxicity criteria (NCI-CTC) grade 4 leukopenia occurred in 10 cases (per 229 cycles). Grade 4 neutropenia occurred in 51 cases, grade 4 thrombocytopenia in 2 cases. Grade 1 mucositis occurred in 32 cases, grade 1 myalgia in 6 cases. CONCLUSIONS: 'docetaxel-5-FU-cisplatin' combination chemotherapy is an active and tolerable regimen as a first-line treatment in patients with metastatic or recurred gastric cancer.

Acute toxic hepatitis caused by an aloe vera preparation in a young patient: a case report with a literature review.

Aloe is one of the leading products used in phytomedicine. Several cases of aloe-induced toxic hepatitis have been reported in recent years. However, its toxicology has not yet been systematically described in the literature. A 21-year-old female patient was admitted to our hospital with acute hepatitis after taking an aloe vera preparation for four weeks. Her history, clinical manifestation, laboratory findings, and histological findings all led to the diagnosis of aloe vera-induced toxic hepatitis. We report herein on a case of acute toxic hepatitis induced by aloe vera.

Improved reversibility in lithium-oxygen battery: understanding elementary reactions and surface charge engineering of metal alloy catalyst.

Most Li-O2 batteries suffer from sluggish kinetics during oxygen evolution reactions (OERs). To overcome this drawback, we take the lesson from other catalysis researches that showed improved catalytic activities by employing metal alloy catalysts. Such research effort has led us to find Pt3Co nanoparticles as an effective OER catalyst in Li-O2 batteries. The superior catalytic activity was reflected in the substantially decreased overpotentials and improved cycling/rate performance compared to those of other catalysts. Density functional theory calculations suggested that the low OER overpotentials are associated with the reduced adsorption strength of LiO2 on the outermost Pt catalytic sites. Also, the alloy catalyst generates amorphous Li2O2 conformally coated around the catalyst and thus facilitates easier decomposition and higher reversibility. This investigation conveys an important message that understanding elementary reactions and surface charge engineering of air-catalysts are one of the most effective approaches in resolving the chronic sluggish charging kinetics in Li-O2 batteries.

Effective liquid-phase exfoliation and sodium ion battery application of MoS2 nanosheets.

Two-dimensional (2D) molybdenum disulfide (MoS2) has been taken much attention for various applications, such as catalyst, energy storage, and electronics. However, the lack of effective exfoliation methods for obtaining 2D materials in a large quantity has been one of the technical barriers for the real applications. We report a facile liquid-phase exfoliation method to improve the exfoliation efficiency for single-layer MoS2 sheets in 1-methyl-2-pyrrolidinone (NMP) with a sodium hydroxide (NaOH) assistant. The concentration of the exfoliated MoS2 nanosheets was greatly improved compared to that achieved with conventional liquid-phase exfoliation methods using NMP solvent. We demonstrate stable operation of sodium-ion battery by using the exfoliated MoS2 and MoS2-rGO composite as anode materials.

Helicobacter pylori seropositivity is positively associated with colorectal neoplasms.

BACKGROUND/AIMS: Helicobacter pylori is a well known precursor to gastric cancer and gastric mucosa-associated lymphoid tissue lymphoma. This study was to determine whether H. pylori was associated with colorectal neoplasms in Korean subjects undergoing routine checkup. METHODS: A total of 10,082 subjects underwent routine checkups from January 2004 to April 2005. A H. pylori IgG test and stool occult blood test were included in the routine checkup program. Colonoscopy was performed if the stool occult blood test was positive or under subject request. Patients who underwent colonoscopy and had histologically confirmed cases of colorectal neoplasms were designanted as the subject group and those without as the control group. RESULTS: Of the 10,082 subjects, 597 had full colonoscopy. The results identified 9 colorectal carcinomas and 118 adenomas. H. pylori seropositivity was identified in 6 (66%) subjects with colorectal carcinoma, 81 (68.6%) with colorectal adenoma and 248 (52.8%) controls. Subjects having colorectal neoplasms had a significantly higher H. pylori seropositivity rate compared with the controls (OR 1.94, 95% CI 1.28-2.95). This remained significant after adjusting for age, sex, body mass index, HbA1c and total cholesterol (OR 1.90, 95% CI 1.23-2.93). Patients with distal neoplasms also had a significantly higher H. pylori seroposivity rate (OR 1.88, 95% CI 1.17-3.01) which persisted after multivariate adjustment (OR 1.79, 95% CI 1.10-2.94). CONCLUSIONS: Subjects with colorectal neoplasms present an increased H. pylori seroprevalence compared with controls.