Polyoxocationic antimony oxide cluster with acidic protons

The success and continued expansion of research on metal-oxo clusters owe largely to their structural richness and wide range of functions. However, while most of them known to date are negatively charged polyoxometalates, there is only a handful of cationic ones, much less functional ones. Here, we show an all-inorganic hydroxyiodide [H_10.7Sb_32.1O₄₄][H_2.1Sb_2.1I₈O₆][Sb_0.76I₆]₂·25H₂O (HSbOI), forming a face-centered cubic structure with cationic Sb₃₂O₄₄ clusters and two types of anionic clusters in its interstitial spaces. Although it is submicrometer in size, electron diffraction tomography of HSbOI allowed the construction of the initial structural model, followed by powder Rietveld refinement to reach the final structure. The cationic cluster is characterized by the presence of acidic protons on its surface due to substantial Sb³⁺ deficiencies, which enables HSbOI to serve as an excellent solid acid catalyst. These results open up a frontier for the exploration and functionalization of cationic metal-oxo clusters containing heavy main group elements.

Oxygen Evolution Reaction Driven by Charge Transfer from a Cr Complex to Co-Containing Polyoxometalate in a Porous Ionic Crystal

Considerable efforts have been devoted to developing oxygen evolution reaction (OER) catalysts based on transition metal oxides. Polyoxometalates (POMs) can be regarded as model compounds of transition metal oxides, and cobalt-containing POMs (Co-POMs) have received significant interest as candidates. Nanocomposites based on Co-POMs have been reported to show high OER activities due to synergistic effects among the components; however, the role of each component is unclear due to its complex structure. Herein, we utilize porous ionic crystals (PICs) based on Co-POMs, which enable a composition-structure-function relationship to be established to understand the origin of the synergistic catalysis. Specifically, a Keggin-type POM [α-CoW₁₂O₄₀]^6- and a Cr complex [Cr₃O(OOCCH₂CN)₆(H₂O)₃]⁺ are implemented as PIC building blocks for the OER under nonbasic conditions. The potentially OER-active but highly soluble [α-CoW₁₂O₄₀]^6- was successfully anchored in the crystalline PIC matrix via Coulomb interactions and hydrogen bonding induced by polar cyano groups of the Cr complex. The PIC exhibits efficient and sustained OER catalytic activity, while each building block is inactive. The Tafel slope of the linear sweep voltammetry curve and the relatively large kinetic isotope effect value suggest that elementary steps closely related to the OER rate involve single-electron and proton transfer reactions. Electrochemical and spectroscopic studies clearly show that the synergistic catalysis originates from the charge transfer from the Cr complex to [α-CoW₁₂O₄₀]^6-; the increased electron density of [α-CoW₁₂O₄₀]^6- may increase its basicity and accelerate proton abstraction as well as enhance electron transfer to stabilize the reaction intermediates adsorbed on [α-CoW₁₂O₄₀]^6-.

High-density magnetic-vacancy inclusion in Co2MnGa single crystal probed by spin-polarized positron annihilation spectroscopy

Co₂MnGa is a Weyl semimetal exhibiting giant anomalous Hall and Nernst effects. Using spin-polarized positron annihilation spectroscopy, we examined a Bridgman-grown Co₂MnGa single crystal with a nearly perfectL2₁-ordered structure and a reference Co₂MnAl polycrystal with a Mn-Al-disorderedB2 structure. We found that a large amount of magnetic vacancies (more than 100 ppm) were included in the Co₂MnGa crystal but not the Co₂MnAl crystal. We discuss possible reasons for the inclusion of vacancies, the role of vacancies in the development of the ordered structure, and the electronic states associated with the vacancies. Toward the development of Co₂MnGa-based devices, the manners for reducing vacancies as well as the influence of vacancies on the electrical transport properties should be considered.

Role of Pyridinic Nitrogen in the Mechanism of the Oxygen Reduction Reaction on Carbon Electrocatalysts

The introduction of pyridinic nitrogen (pyri-N) into carbon-based electrocatalysts for the oxygen reduction reaction is considered to create new active sites. Herein, the role of pyri-N in such catalysts was investigated from a mechanistic viewpoint using carbon black (CB)-supported pyri-N-containing molecules as model catalysts; the highest activity was observed for 1,10-phenanthroline/CB. X-ray photoemission spectroscopy showed that in acidic electrolytes, both pyri-N atoms of 1,10-phenanthroline could be protonated to form pyridinium ions (pyri-NH⁺ ). In O₂ -saturated electrolytes, one of the pyri-NH⁺ species was reduced to pyri-NH upon the application of a potential; no such reduction was observed in N₂ -saturated electrolytes. This behavior was ascribed to electrochemical reduction of pyri-NH⁺ occurring simultaneously with the thermal adsorption of O₂ , as supported by DFT calculations. According to these calculations, the coupled reduction was promoted by hydrophobic environments.

Isostructural mesoporous ionic crystals as a tunable platform for acid catalysis

Eleven isostructural mesoporous ionic crystals (meso-PICs) are synthesized. The initial activities of the Barbier-Grignard reaction, which is a typical C-C bond formation reaction, catalyzed by the meso-PICs are dependent on the acid dissociation constant of the aqua ions of Mn+ and the types of polyoxometalates, which construct the meso-PICs.

Amorphous High-Surface-Area Aluminum Hydroxide-Bicarbonates for Highly Efficient Methyl Orange Removal from Water

Amorphous high-surface-area aluminum hydroxide-bicarbonates were synthesized starting from AlCl₃, base, and bicarbonate in water. Composites with a chemical formulas of [Al₁₃O₄(μ-OH)₂₄(H₂O)_6.5(OH)_5.5](HCO₃)_1.5 (I-NaOH) and [Al₁₃O₄(μ-OH)₂₄(H₂O)₆(OH)₆](HCO₃) (I-NH₃) were obtained by the use of NaOH/NaHCO₃ and NH₃/NH₄HCO₃ as base/bicarbonate, respectively. The surface area of the composites was highly dependent on the pH level of the synthetic solution, and composites with high surface areas (ca. 200 m² g^-1) were obtained around pH 7-8. Pore-size distributions determined from the N₂ adsorption isotherms showed that I-NH₃ and I-NaOH possess mainly large (pore radius r_p > 3 nm) and small (r_p < 3 nm) pores, respectively, despite similar surface areas. While SEM images showed that both I-NH₃ and I-NaOH were aggregates of nanoparticles, the particles were more fused in I-NaOH, which is in line with the existence of small pores and the use of a stronger base (NaOH), which would facilitate the dehydration condensation reaction. The composites were applied as adsorbents to remove methyl orange (MO) from water. The time course of MO adsorption was readily fitted with a pseudo-second-order model, and over 90% MO removal was attained within 10 min with I-NH₃, while I-NaOH showed much less MO removal (26%). The MO adsorption isotherm of I-NH₃ was reproduced with a Langmuir model with an adsorption capacity of 154 mg g^-1. Notably, the aluminum hydroxide-bicarbonates could not absorb methylene blue, which is a cationic dye, while anions (MO and PO₄^3-) were readily absorbed. Solid-state ²⁷Al MAS NMR spectra showed that the concentration of 5-coordinated aluminum species, which may serve as guest binding sites, was higher for I-NH₃. These results show that electrostatic interaction between anionic MO and coordinatively unsaturated 5-coordinated cationic aluminum species and the large external surface area of I-NH₃ contribute to the highly efficient MO adsorption.

Benign hilar bile duct strictures resected as perihilar cholangiocarcinoma

BACKGROUND

Differentiation between perihilar cholangiocarcinoma (PHCC) and benign strictures is frequently difficult. The aim of this study was to investigate the incidence and long-term outcome of patients with tumours resected because of suspicion of PHCC, which ultimately turned out to be benign (malignancy masquerade).

METHODS

Patients who underwent surgical resection with a diagnosis of PHCC between 2001 and 2016 were reviewed retrospectively.

RESULTS

Among 707 consecutive patients, 685 had PHCC and the remaining 22 (3·1 per cent) had benign biliary stricture. All patients with benign disease underwent major hepatectomy, with no deaths. Preoperative histological assessment using bile duct biopsy or aspiration cytology had a high specificity (90 per cent), low sensitivity (62 per cent) and unsatisfactory accuracy (63 per cent). Despite the increasing use of histological assessment, the incidence of benign strictures resected did not decrease over time, being 0·9 per cent in 2001-2004, 4·0 per cent in 2005-2008, 3·8 per cent in 2009-2012 and 2·9 per cent in 2013-2016. The final pathology of benign strictures included IgG4-related sclerosing cholangitis (9 patients), hepatolithiasis (4), granulomatous cholangitis (3), non-specific chronic cholangitis (3), benign strictures after cholecystectomy (2), and a benign stricture possibly caused by parasitic infection (1). The 10-year overall survival rate for the 22 patients with benign stricture was 87 per cent, without recurrence of biliary stricture.

CONCLUSION

The incidence of benign strictures resected as PHCC as a proportion of all resections was relatively low, at 3·1 per cent. Currently, unnecessary surgery for suspected PHCC is unavoidable.

Clinical value of additional resection of a margin-positive distal bile duct in perihilar cholangiocarcinoma

Background

Little is known about the effect of additional resection for a frozen-section-positive distal bile duct margin (DM) in perihilar cholangiocarcinoma.

Methods

Patients who underwent surgical resection for perihilar cholangiocarcinoma between 2001 and 2015 were analysed retrospectively, focusing on the DM.

Results

Of 558 consecutive patients who underwent frozen-section examination for a DM, 74 (13·3 per cent) had a frozen-section-positive DM with invasive cancer or carcinoma in situ. Eventually, 53 patients underwent additional resection (bile duct resection in 44 and pancreatoduodenectomy in 9), whereas the remaining 21 patients did not. Ultimately, R0 resection was achieved in 30 of the 53 patients (57 per cent). No patient who underwent additional resection died from surgical complications. The 44 patients with additional bile duct resection had a 5-year overall survival rate of 31 per cent. Overall survival of the nine patients who had pancreatoduodenectomy was better, with a 10-year rate of 67 per cent. Survival of the 21 patients without additional resection was dismal: all died within 5 years. Multivariable analyses identified nodal status and additional resection as independent prognostic factors (lymph node metastasis: hazard ratio (HR) 2·26, 95 per cent c.i. 1·26 to 4·07; bile duct resection versus no additional resection: HR 0·32, 0·17 to 0·60; pancreatoduodenectomy versus no additional resection: HR 0·08, 0·02 to 0·29).

Conclusion

Additional resection for frozen-section-positive DM in perihilar cholangiocarcinoma frequently yields R0 margins. It offers a better chance of long-term survival, and thus should be performed in carefully selected patients.

Synthesis of Conjugated Polymers Containing Octafluorobiphenylene Unit via Pd-Catalyzed Cross-Dehydrogenative-Coupling Reaction

Polycondensation via Pd-catalyzed cross-dehydrogenative-coupling reaction of 2,2',3,3',5,5',6,6'-octafluorobiphenyl with thiophene analogues was studied. The synthetic protocol, in which employment of prefunctionalized starting monomers was fully avoided, allowed straightforward access to an alternating π-conjugated polymer. The addition of K₂CO₃ to the catalytic system promotes the cross-coupling reaction and suppresses the undesired homocoupling reaction, producing the corresponding donor-acceptor type π-conjugated polymers with minor homocoupling defects. The reaction also proceeded using O₂ as the terminal oxidant, resulting in lower loading of the Ag oxidant. The obtained polymer was evaluated as an emitting material for an organic light-emitting diode.

Expression of Monocarboxylate Transporter 1 in Oral and Ocular Canine Melanocytic Tumors

Solid tumors are composed of a heterogeneous population of cells surviving in various concentrations of oxygen. In a hypoxic environment, tumor cells generally up-regulate glycolysis and, therefore, generate more lactate that must be expelled from the cell through proton transporters to prevent intracellular acidosis. Monocarboxylate transporter 1 (MCT1) is a major proton transporter in mammalian cells that transports monocarboxylates, such as lactate and pyruvate, together with a proton across the plasma membrane. Melanocytic neoplasia occurs frequently in dogs, but the prognosis is highly site-dependent. In this study, 50 oral canine melanomas, which were subdivided into 3 histologic subtypes, and 17 ocular canine melanocytic neoplasms (14 melanocytomas and 3 melanomas) were used to examine and compare MCT1 expression. Immunohistochemistry using a polyclonal chicken anti-rat MCT1 antibody showed that most oral melanoma exhibited cell membrane staining, although there were no significant differences observed among the 3 histologic subtypes. In contrast, the majority of ocular melanocytic tumors were not immunoreactive. Additionally, we documented the presence of a 45-kDa band in cell membrane protein Western blots, and sequencing of a reverse transcriptase polymerase chain reaction band of expected size confirmed its identity as a partial canine MCT1 transcript in 3 oral tumors. Increased MCT1 expression in oral melanomas compared with ocular melanocytic tumors may reflect the very different biology between these tumors in dogs. These results are the first to document canine MCT1 expression in canine tumors and suggest that increased MCT1 expression may provide a potential therapeutic target for oral melanoma.

Variant parameter values-as defined by the Chicago Criteria-produced by ManoScan and a new system with Unisensor catheter

BACKGROUND

Recently reported normal values for esophageal motility obtained by high-resolution manometry (HRM) using a system with a Unisensor catheter were significantly different from those obtained by the ManoScan(®) , which could result in a wrong diagnosis. To clarify whether these differences were due to system or subject differences, we compared the manometric parameter values between ManoScan and a new system with a Unisensor catheter (Starlet) in the same subjects.

METHODS

A total of 103 volunteers without any symptoms related to esophageal motility disorders were recruited. Esophageal HRM was performed using both the ManoScan and the Starlet in all subjects. Data from the ManoScan were analyzed using ManoView, and data from the Starlet were analyzed by a program with e-sleeve function. Integrated relaxation pressure, distal contractile integral, contractile front velocity (CFV), intrabolus pressure, and distal latency were calculated by both analyzing programs, and the values of these parameters were compared between the two systems by a signed rank test.

KEY RESULTS

Data from a total of 97 participants were analyzed. The values of all parameters, except CFV, measured by the Starlet were significantly higher than those obtained by the ManoScan (p < 0.01).

CONCLUSIONS & INFERENCES

Both systems can measure esophageal motility appropriately; nevertheless, we confirmed that the two systems showed different values of the parameters defined by the Chicago criteria. These differences should be recognized to evaluate esophageal motility precisely.

Gastrointestinal symptoms in idiopathic pulmonary fibrosis patients treated with pirfenidone and herbal medicine

Pirfenidone is an antifibrotic agent for patients with pulmonary fibrosis, but this drug has adverse gastrointestinal (GI) effects. The first aim of this study was to assess GI symptoms due to pirfenidone by using a new questionnaire for reflux symptoms and dismotility symptoms. Whether adding herbal medicine of rikkunshi-to improved GI symptoms due to pirfenidone therapy was also investigated. This was a randomized controlled trial performed on 17 IPF patients. The patients were assigned to two groups, and the study period was 8 weeks. The pirfenidone group received pirfenidone therapy for 8 weeks with add-on rikkunshi-to from 4 weeks, while the control group did not receive either of these agents. To assess the effects of RK, plasma levels of acyl-ghrelin and des-acyl-ghrelin, serum KL-6 and surfactant protein-D, and pulmonary function tests were monitored. GI symptoms were most severe during the initial 2 weeks of pirfenidone therapy at a dose of 600 mg/day. Both reflux symptoms and dismotility symptoms deteriorated. Rikkunshi-to improved GI symptoms to the level prior to pirfenidone therapy. Plasma levels of des-acyl-ghrelin and acyl-/des-acyl-ghrelin ratio changed significantly at 8 weeks compared to 2 weeks. GI adverse events due to PFD were most severe in the first 2 weeks of treatment at a dose of 600 mg/day, and both reflux and dismotility symptoms deteriorated, but the drug was well tolerated at 1200 mg/day. Rikkunshi-to contributed to improvement of GI symptoms, but plasma ghrelin levels did not reflect the improvement of GI symptoms.

Role of anatomical right hepatic trisectionectomy for perihilar cholangiocarcinoma

BACKGROUND

Right-sided hepatectomy is often selected for perihilar cholangiocarcinoma because the extrahepatic portion of the left hepatic duct is longer than that of the right hepatic duct. However, the length of resected left hepatic duct in right-sided hepatectomy has not been reported.

METHODS

Patients who underwent right-sided hepatectomy for perihilar cholangiocarcinoma were reviewed retrospectively. Trisectionectomies were performed according to a previously reported technique of anatomical right hepatic trisectionectomy. Right hepatectomy was performed according to standard operative procedures. The length of resected left hepatic duct was measured.

RESULTS

Thirty-three patients underwent right trisectionectomy and 141 had a right hemihepatectomy. Patients having a trisectionectomy had more advanced tumours and so required combined portal vein resection more frequently. Duration of surgery and blood loss were similar in the two groups. Morbidity and mortality rates tended to be higher following hemihepatectomy than after trisectionectomy. The mean(s.d.) length of resected left hepatic duct was significantly greater in trisectionectomy than in hemihepatectomy (25·0(6·9) versus 14·8(5·3) mm; P < 0·001). In patients with Bismuth type IV tumours, the percentage of negative left hepatic duct margins was significantly higher for trisectionectomy than for hemihepatectomy (89 versus 57 per cent; P = 0·021). Achievement of R0 resection was similar and survival did not differ between the two groups, despite different tumour load.

CONCLUSION

Compared with right hemihepatectomy, anatomical right hepatic trisectionectomy provides a greater length of resected hepatic duct, leading to a high proportion of negative proximal ductal margins even in patients with Bismuth type IV tumours.

Total spondylectomy following carbon ion radiotherapy to treat chordoma of the mobile spine

The main form of treatment of a chordoma of the mobile spine is total en bloc spondylectomy (TES), but the clinical results are not satisfactory. Stand-alone carbon ion radiotherapy (CIRT) for bone and soft-tissue sarcomas has recently been reported to have a high rate of local control with a low rate of local recurrence. We report two patients who underwent TES after CIRT for treating a chordoma in the lumbar spine with good medium-term outcomes. At operation, there remained histological evidence of viable tumour cells in both cases. After the combination use of TES following CIRT, neither patient showed signs of recurrence at the follow-up examination. These two cases suggest that CIRT should be combined with total spondylectomy in the treatment of chordoma of the mobile spine.

Metre-long cell-laden microfibres exhibit tissue morphologies and functions

Artificial reconstruction of fibre-shaped cellular constructs could greatly contribute to tissue assembly in vitro. Here we show that, by using a microfluidic device with double-coaxial laminar flow, metre-long core-shell hydrogel microfibres encapsulating ECM proteins and differentiated cells or somatic stem cells can be fabricated, and that the microfibres reconstitute intrinsic morphologies and functions of living tissues. We also show that these functional fibres can be assembled, by weaving and reeling, into macroscopic cellular structures with various spatial patterns. Moreover, fibres encapsulating primary pancreatic islet cells and transplanted through a microcatheter into the subrenal capsular space of diabetic mice normalized blood glucose concentrations for about two weeks. These microfibres may find use as templates for the reconstruction of fibre-shaped functional tissues that mimic muscle fibres, blood vessels or nerve networks in vivo.

Propeptide processing and proteolytic activity of proenzymes of the staphylococcal and enterococcal GluV8-family protease

Proenzymes with various lengths of propeptides have been observed in GluV8 from Staphylococcus aureus and GluSE from S. epidermidis. However, the production mechanism of these proenzymes and roles of truncated propeptides have yet to be elucidated. Here we demonstrate that shortening of propeptide commonly occurs in an auto-catalytic manner in GluV8-family members, including those from coagulase negative Staphylococci and Enterococcus faecalis. Accompanied with propeptide shortening, the pro-mature junction (Asn/Ser_1-Val1) becomes more susceptible towards the hetero-catalytic maturation enzymes. The auto-catalytic propeptide truncation is not observed in Ser169Ala inert molecules of GluV8-family members. A faint proteolytic activity of proenzymes from Staphylococcus caprae and E. faecalis is detected. In addition, proteolytic activity of proenzyme of GluV8 carrying Arg-3AlaAsn.1 is demonstrated with synthetic peptide substrates LLE/Q-MCA. These results suggest that GluV8-family proenzymes with shortened propeptides intrinsically possess proteolytic activity and are involved in the propeptide shortening that facilitates the final hetero-catalytic maturation.

Monosodium glutamate stimulates secretion of glucagon-like peptide-1 and reduces postprandial glucose after a lipid-containing meal

BACKGROUND

Monosodium l-glutamate (MSG) is known to influence the endocrine system and gastrointestinal (GI) motility. The mechanism of postprandial glycemic control by food in the GI tract is mostly unknown and of great interest.

AIM

To investigate the effect of MSG on glucose homeostasis, incretin secretion and gastric emptying in humans after a lipid-containing meal.

METHODS

Thirteen healthy male volunteers (mean age, 25.5 years) and with no Helicobcter pylori infection were enrolled. A 400 mL (520 kcal) liquid meal with MSG (2 g, 0.5% wt:vol) or NaCl (control) was ingested in a single-blind placebo-controlled cross-over study. Blood glucose, serum insulin, plasma glucagon, plasma glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide were measured. Gastric emptying was monitored by a 13C acetate breath test. Postprandial symptoms were assessed on a visual analogue scale.

RESULTS

The 30-min postprandial glucose concentration was significantly reduced by adding MSG to the test meal. The area under the glucose concentration vs. time curve (0-60 min) was also significantly reduced by adding MSG (40.6 ± 3.51 mg·1 hr/dL with MSG vs. 49.2 ± 3.86 mg·1 hr/dL with NaCl, P = 0.047), whereas, the 30-min postprandial plasma GLP-1 level was significantly increased (58.1 ± 15.8 pmol/L with MSG vs. 13.4 ± 15.8 pmol/L with NaCl, P = 0.035). MSG did not affect the half gastric emptying time or postprandial symptoms.

CONCLUSIONS

Monosodium l-glutamate improved early postprandial glycaemia after a lipid-containing liquid meal. This effect was not associated with a change in gastric emptying, but was possibly related to stimulation of glucagon-like peptide-1 secretion.

Cascade stomach is associated with upper gastrointestinal symptoms: a population-based study

BACKGROUND

Cascade stomach (CS) is recognized by characteristic findings on barium studies. We prospectively investigated the relationship between CS and upper gastrointestinal (GI) symptoms.

METHODS

In subjects undergoing health screening, CS was diagnosed by barium studies. Consecutive persons (500 men and 127 women) with CS were identified and the same number of age-matched subjects without CS were selected as controls. Upper GI symptoms were classified as reflux symptoms, dyspepsia symptoms, or epigastralgia symptoms. Then, we prospectively analyzed barium studies to classify the gastric morphology and also assessed upper GI symptoms in consecutive 5008 men and 2736 women.

KEY RESULTS

BMI was significantly higher in men with CS than in controls, and also in women with CS than in controls. Upper GI symptoms were significantly more frequent in the CS group than the controls among both men and women, especially reflux symptoms. In men, logistic regression analysis identified CS as an independent risk factor for upper GI symptoms (odds ratio = 1.771, P = 0.005) and for reflux symptoms (odds ratio = 2.07, P = 0.009). In women, CS was also significantly related to upper GI symptoms (odds ratio = 2.544, P = 0.020). The prevalence of CS was significantly higher (P < 0.0001) among symptomatic men than among those with no symptoms.

CONCLUSIONS & INFERENCES

Gastric morphology is related to upper GI symptoms in both men and women. Cascade stomach should be reconsidered as a pathophysiological factor associated with upper GI symptoms.

Increase of weakly acidic gas esophagopharyngeal reflux (EPR) and swallowing-induced acidic/weakly acidic EPR in patients with chronic cough responding to proton pump inhibitors

BACKGROUND

Gastro-esophageal reflux disease (GERD)-related chronic cough (CC) may have multifactorial causes. To clarify the characteristics of esophagopharyngeal reflux (EPR) events in CC patients whose cough was apparently influenced by gastro-esophageal reflux (GER), we studied patients with CC clearly responding to full-dose proton pump inhibitor (PPI) therapy (CC patients).

METHODS

Ten CC patients, 10 GERD patients, and 10 healthy controls underwent 24-h ambulatory pharyngo-esophageal impedance and pH monitoring. Weakly acidic reflux was defined as a decrease of pH by >1 unit with a nadir pH >4. In six CC patients, monitoring was repeated after 8 weeks of PPI therapy. The number of each EPR event and the symptom association probability (SAP) were calculated. Symptoms were evaluated by a validated GERD symptom questionnaire.

KEY RESULTS

Weakly acidic gas EPR and swallowing-induced acidic/weakly acidic EPR only occurred in CC patients, and the numbers of such events was significantly higher in the CC group than in the other two groups (P < 0.05, respectively). Symptom association probability analysis revealed a positive association between GER and cough in three CC patients. Proton pump inhibitor therapy abolished swallowing-induced acidic/weakly acidic EPR, reduced weakly acidic gas EPR, and improved symptoms (all P < 0.05).

CONCLUSIONS & INFERENCES

Most patients with CC responding to PPI therapy had weakly acidic gas EPR and swallowing-induced acidic/weakly acidic EPR. A direct effect of acidic mist or liquid refluxing into the pharynx may contribute to chronic cough, while cough may also arise indirectly from reflux via a vago-vagal reflex in some patients.

Prospective study of biliary cytology in suspected perihilar cholangiocarcinoma

BACKGROUND

The diagnostic value of biliary cytology for hilar bile duct stricture is uncertain. This study prospectively examined three methods for the evaluation of biliary cytology in a consecutive group of patients.

METHODS

Preoperative bile sampling by aspiration through a drainage catheter (aspiration samples), saline flush through a drainage catheter (saline samples) or direct sampling from a drainage bag (bag samples) was performed in consecutive patients with suspected perihilar cholangiocarcinoma who underwent resection after endoscopic nasobiliary drainage or percutaneous transhepatic biliary drainage. All bile sampling was performed three times on separate days. The accuracy of cytology in the diagnosis of carcinoma was determined.

RESULTS

Of 100 consecutive patients with hilar strictures, 97 had histologically proven cholangiocarcinoma. The proportion of these 97 patients who had a positive finding on cytology in at least one of three sampling sessions was 55 per cent for aspiration samples, 48 per cent for bag samples and 38 per cent for saline samples (P = 0·021, aspiration versus saline). Tumour length correlated significantly with overall positivity. For aspiration samples, sensitivity was 55 per cent, specificity was 100 per cent and accuracy 56·0 per cent.

CONCLUSION

For biliary cytology, sampling by catheter aspiration is more effective than catheter flushing or sampling from a drainage bag. Repeated sampling increases sensitivity. Biliary cytology has modest diagnostic yield, but is easy to perform, highly specific, and can provide a definitive diagnosis.

Mechanism of gastroesophageal reflux in patients with obstructive sleep apnea syndrome

BACKGROUND

It has been reported that the prevalence of gastroesophageal reflux (GER) disease is high in patients with obstructive sleep apnea (OSA). End-inspiratory intra-esophageal pressure decreases progressively during OSA, which has been thought to facilitate GER in OSA patients. The aim of our study was to clarify the mechanisms of GER during sleep (sleep-GER) in OSA patients.

METHODS

Eight OSA patients with reflux esophagitis (RE), nine OSA patients without RE, and eight healthy controls were studied. Polysomnography with concurrent esophageal manometry and pH recording were performed.

KEY RESULTS

Significantly more sleep-GER occurred in OSA patients with RE than without RE or in controls (P < 0.05). The severity of OSA did not differ between OSA patients with RE and without RE. Sleep-GER was mainly caused by transient lower esophageal sphincter relaxation (TLESR), but not by negative intra-esophageal pressure during OSA. During OSA gastroesophageal junction pressure progressively increased synchronous to intra-esophageal pressure decrease. OSA patients had significantly more TLESR events during sleep related to preceding arousals and shallow sleep, but the number of TLESR events was not related to RE.

CONCLUSIONS & INFERENCES

In OSA patients, sleep-GER was mainly caused by TLESR, but not by negative intra-esophageal pressure due to OSA.

Factors related to the advantageous effects of wearing a wetsuit during swimming at different submaximal velocity in triathletes

This study was designed to compare the effects of wetsuit (WS) to swimsuit (SS) at identical relative velocities in a swimming flume. Thirteen triathletes performed a continuous progressive swimming test and submaximal steady state swimming tests with a WS and with a SS. Maximal oxygen uptake (VO2max) and the associated velocity at which the VO2max was achieved (VVO2max) were determined during the continuous progressive tests. Two 5 min swims (at 60% VVO2max (V(60%)) and 80% VVO2max (V(80%))) were then conducted to measure VO2max, blood lactate concentration (LA), rating of perceived exertion (RPE), the energy cost of swimming (Cs), stroke rate (SR) and stroke length (SL). No difference was found in VO2max, but VVO2max with a WS was 5.4% higher than with a SS. VO2 with a WS was lower than with a SS alone at V(60%), but not at V(80%). Cs with a WS was lower by 14.4% at V(60%) and 7.5% at V(80%) than with a SS. No differences were found in LA and RPE between suit conditions during both submaximal swims. Wearing a WS did not affect SL, but SR tended to be higher in a WS for both submaximal velocities. These results suggest that the benefits of wearing a WS are not only improvement in swimming performance and propulsion efficiency, but reduction in gross energy consumption in the swimming portion of triathlon races. Furthermore, when wearing a WS, incremental changes in SR rather than SL are associated with improved swimming performance.