Publications by authors named "Takeshi Hasegawa"

175 Publications

Nonconvulsive status epilepticus following rotavirus gastroenteritis in two pediatric patients.

Brain Dev 2021 May 29. Epub 2021 May 29.

Department of Pediatrics, Soka Municipal Hospital, Saitama, Japan.

Background: Nonconvulsive status epilepticus (NCSE) comprises a range of conditions in which prolonged electrographic seizures result in nonconvulsive clinical symptoms. An understanding of NCSE is especially important in emergency care. Among the various causes of NCSE, an infectious etiology has been rarely reported to date.

Case Reports: We report two pediatric cases of rotavirus gastroenteritis complicated by NCSE. In both cases, bilateral rhythmic delta activity (2.5-3 Hz) with occipital predominance fluctuated with the patient's consciousness level. The paroxysmal waves disappeared completely and consciousness immediately and remarkably improved after intravenous midazolam infusion. The patients remained alive 10 and 2 years, respectively, after short-term oral anticonvulsant administration, with no epileptic seizures.

Conclusion: The etiology of NCSE was identical and the clinical presentations were analogous in the two patients. The seizure semiology differed from that in benign convulsion with gastroenteritis. NCSE was considered the prominent cause of neurological symptoms; however, the pathogenic mechanism remains unclear, including the coexistence of acute encephalopathy.
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http://dx.doi.org/10.1016/j.braindev.2021.05.008DOI Listing
May 2021

Association between Dipeptidyl Peptidase-4 Inhibitor Prescription and Erythropoiesis-Stimulating Agent Hyporesponsiveness in Hemodialysis Patients with Diabetes Mellitus.

Kidney Blood Press Res 2021 Apr 22:1-10. Epub 2021 Apr 22.

Division of Nephrology and Endocrinology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan.

Introduction: Dipeptidyl peptidase-4 (DPP-4) has been hypothesized to improve responsiveness to erythropoiesis-stimulating agent (ESA). We aimed to describe the trend in DPP-4 inhibitor prescription patterns and assess the association between DPP-4 inhibitor prescription and ESA hyporesponsiveness (eHypo) in Japanese hemodialysis (HD) patients with diabetes mellitus (DM).

Methods: We analyzed data from the Japan Dialysis Outcomes and Practice Patterns Study phase 4-6 (2009-2017) on patients with DM who underwent HD thrice per week for at least 4 months. The primary exposure of interest was having a DPP-4 inhibitor prescription. The primary analysis outcomes were a binary indicator of eHypo (mean hemoglobin <10 and mean ESA dose >6,000 units/week over 4 months) and the natural log-transformed ESA resistance index (ERI). We used conditional logistic regression to compare within-patient changes in eHypo before and after initial DPP-4 inhibitor prescription. We used linear generalized estimating equation models to compare continuous ERI outcomes while accounting for within-patient repeated measurements with an exchangeable correlation structure.

Results: There was a monotonic increase in DPP-4 inhibitor prescription according to study year up to 20% in 2017. Moreover, 12.8% of patients with a DPP-4 inhibitor prescription were ESA hyporesponsive before the initial DPP-4 inhibitor prescription. After DPP-4 inhibitor prescription, the odds of eHypo and mean log-ERI remained unchanged in the whole cohort of our study. The interaction analysis of DPP-4 inhibitor and sideropenia showed that DPP-4 inhibitors attenuated eHypo in the patients without iron deficiency.

Conclusion: Our findings indicate a recent increase in DPP-4 inhibitor prescription among Japanese HD patients with DM. DPP-4 inhibitors could improve ERI in patients undergoing HD without iron deficiency.
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http://dx.doi.org/10.1159/000515704DOI Listing
April 2021

Clinical Characteristics of Fragile X Syndrome Patients in Japan.

Yonago Acta Med 2021 Feb 6;64(1):30-33. Epub 2021 Jan 6.

Division of Clinical Genetics, Tottori University Hospital, Yonago 680-8504, Japan.

Background: Fragile X syndrome (FXS) is a well-known X-linked disorder clinically characterized by intellectual disability and autistic features. However, diagnosed Japanese FXS cases have been fewer than expected, and clinical features of Japanese FXS patients remain unknown.

Methods: We evaluated the clinical features of Japanese FXS patients using the results of a questionnaire-based survey.

Results: We presented the characteristics of seven patients aged 6 to 20 years. Long face and large ears were observed in five of seven patients. Macrocephaly was observed in four of five patients. The meaningful word was first seen at a certain time point between 18 and 72 months (median = 60 months). Developmental quotient or intellectual quotient ranged between 20 and 48 (median = 29). Behavioral disorders were seen in all patients (autistic spectrum disorder in six patients, hyperactivity in five patients). Five patients were diagnosed by polymerase chain reaction analysis, and two patients were diagnosed by the cytogenetic study. All physicians ordered FXS genetic testing for suspicious cases because of clinical manifestations.

Conclusion: In the present study, a long face, large ears, macrocephaly, autistic spectrum disorder, and hyperactivity were observed in almost cases, and these characteristics might be common features in Japanese FXS patients. Our finding indicated the importance of clinical manifestations to diagnosis FXS. However, the sample size of the present study is small, and these features are also seen to patients with other disorders. We consider that genetic testing for FXS should be performed on a wider range of intellectually disabled cases.
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http://dx.doi.org/10.33160/yam.2021.02.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7902172PMC
February 2021

Added value of clinical prediction rules for bacteremia in hemodialysis patients: An external validation study.

PLoS One 2021 22;16(2):e0247624. Epub 2021 Feb 22.

Fukushima Medical University, Fukushima, Japan.

Introduction: Having developed a clinical prediction rule (CPR) for bacteremia among hemodialysis (HD) outpatients (BAC-HD score), we performed external validation.

Materials & Methods: Data were collected on maintenance HD patients at two Japanese tertiary-care hospitals from January 2013 to December 2015. We enrolled 429 consecutive patients (aged ≥ 18 y) on maintenance HD who had had two sets of blood cultures drawn on admission to assess for bacteremia. We validated the predictive ability of the CPR using two validation cohorts. Index tests were the BAC-HD score and a CPR developed by Shapiro et al. The outcome was bacteremia, based on the results of the admission blood cultures. For added value, we also measured changes in the area under the receiver operating characteristic curve (AUC) using logistic regression and Net Reclassification Improvement (NRI), in which each CPR was added to the basic model.

Results: In Validation cohort 1 (360 subjects), compared to a Model 1 (Basic Model) AUC of 0.69 (95% confidence interval [95% CI]: 0.59-0.80), the AUC of Model 2 (Basic model + BAC-HD score) and Model 3 (Basic model + Shapiro's score) increased to 0.8 (95% CI: 0.71-0.88) and 0.73 (95% CI: 0.63-0.83), respectively. In validation cohort 2 (96 subjects), compared to a Model 1 AUC of 0.81 (95% CI: 0.68-0.94), the AUCs of Model 2 and Model 3 increased to 0.83 (95% CI: 0.72-0.95) and 0.85 (95% CI: 0.76-0.94), respectively. NRIs on addition of the BAC-HD score and Shapiro's score were 0.3 and 0.06 in Validation cohort 1, and 0.27 and 0.13, respectively, in Validation cohort 2.

Conclusion: Either the BAC-HD score or Shapiro's score may improve the ability to diagnose bacteremia in HD patients. Reclassification was better with the BAC-HD score.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0247624PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7899347PMC
February 2021

Self-reported Pruritus and Clinical, Dialysis-Related, and Patient-Reported Outcomes in Hemodialysis Patients.

Kidney Med 2021 Jan-Feb;3(1):42-53.e1. Epub 2020 Nov 21.

Arbor Research Collaborative for Health, Ann Arbor, MI.

Rationale & Objective: Chronic kidney disease (CKD)-associated pruritus, generalized itching related to CKD, affects many aspects of hemodialysis patients' lives. However, information regarding the relationship between pruritus and several key outcomes in hemodialysis patients remains limited.

Study Design: Prospective cohort.

Setting & Participants: 23,264 hemodialysis patients from 21 countries in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases 4 to 6 (2009-2018).

Exposure: Pruritus severity, based on self-reported degree to which patients were bothered by itchy skin (5-category ordinal scale from "not at all" to "extremely").

Outcomes: Clinical, dialysis-related, and patient-reported outcomes.

Analytical Approach: Cox regression for time-to-event outcomes and modified Poisson regression for binary outcomes, adjusted for potential confounders.

Results: The proportion of patients at least moderately bothered by pruritus was 37%, and 7% were extremely bothered. Compared with the reference group ("not at all"), the adjusted mortality HR for patients extremely bothered by pruritus was 1.24 (95% CI, 1.08-1.41). Rates of cardiovascular and infection-related deaths and hospitalizations were also higher for patients extremely versus not at all bothered by pruritus (HR range, 1.17-1.44). Patients extremely bothered by pruritus were also more likely to withdraw from dialysis and miss hemodialysis sessions and were less likely to be employed. Strong monotonic associations were observed between pruritus severity and longer recovery time from a hemodialysis session, lower physical and mental quality of life, increased depressive symptoms, and poorer sleep quality.

Limitations: Residual confounding, recall bias, nonresponse bias.

Conclusions: Our findings demonstrate how diverse and far-reaching poor outcomes are for patients who experience CKD-associated pruritus, specifically those with more severe pruritus. There is need for change in practice patterns internationally to effectively identify and treat patients with pruritus to reduce symptom burden and improve quality of life and possibly even survival.
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http://dx.doi.org/10.1016/j.xkme.2020.08.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7873756PMC
November 2020

Aldosterone antagonists for people with chronic kidney disease requiring dialysis.

Cochrane Database Syst Rev 2021 02 15;2:CD013109. Epub 2021 Feb 15.

Department of Data Science, The Institute of Statistical Mathematics, Tokyo, Japan.

Background: People with chronic kidney disease (CKD) requiring dialysis are at a particularly high risk of cardiovascular death and morbidity. Several clinical studies suggested that aldosterone antagonists would be a promising treatment option for people undergoing dialysis. However, the clinical efficacy and potential harm of aldosterone antagonists for people with CKD on dialysis has yet to be determined.

Objectives: This review aimed to evaluate the benefits and harms of aldosterone antagonists, both non-selective (spironolactone) and selective (eplerenone), in comparison to control (placebo or standard care) in people with CKD requiring haemodialysis (HD) or peritoneal dialysis (PD).

Search Methods: We searched the Cochrane Kidney and Transplant Register of Studies up to 5 August 2020 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

Selection Criteria: We included parallel randomised controlled trials (RCTs), cross-over RCTs, and quasi-RCTs (where group allocation is by a method that is not truly random, such as alternation, assignment based on alternate medical records, date of birth, case record number, or other predictable methods) that compared aldosterone antagonists with placebo or standard care in people with CKD requiring dialysis.

Data Collection And Analysis: Two review authors independently extracted data and assessed risk of bias for included studies. We used a random-effects model meta-analysis to perform a quantitative synthesis of the data. We used the I² statistic to measure heterogeneity among the studies in each analysis. We indicated summary estimates as a risk ratio (RR) for dichotomous outcomes, mean difference (MD) for continuous outcomes, or standardised mean differences (SMD) if different scales were used, with their 95% confidence interval (CI). We assessed the certainty of the evidence for each of the main outcomes using the GRADE (Grades of Recommendation, Assessment, Development, and Evaluation) approach.

Main Results: We included 16 studies (14 parallel RCTs and two cross-over RCTs) involving a total of 1446 participants. Thirteen studies compared spironolactone to placebo or standard care and one study compared eplerenone to a placebo. Most included studies had an unclear or high risk of bias. Compared to control, aldosterone antagonists probably reduced the risk of death (any cause) for people with CKD requiring dialysis (9 studies, 1119 participants: RR 0.45, 95% CI 0.30 to 0.67; I² = 0%; moderate certainty of evidence). Aldosterone antagonist probably decreased the risk of death due to cardiovascular disease (6 studies, 908 participants: RR 0.37, 95% CI 0.22 to 0.64; I² = 0%; moderate certainty of evidence) and cardiovascular and cerebrovascular morbidity (3 studies, 328 participants: RR 0.38, 95% CI 0.18 to 0.76; I² = 0%; moderate certainty of evidence). While aldosterone antagonists probably increased risk of gynaecomastia compared with control (4 studies, 768 participants: RR 5.95, 95% CI 1.93 to 18.3; I² = 0%; moderate certainty of evidence), aldosterone antagonists may make little or no difference to the risk of hyperkalaemia (9 studies, 981 participants: RR 1.41, 95% CI 0.72 to 2.78; I² = 47%; low certainty of evidence). Aldosterone antagonists had a marginal effect on left ventricular mass among participants undergoing dialysis (8 studies, 633 participants: SMD -0.42, 95% CI -0.78 to 0.05; I² = 77%). In people with CKD requiring dialysis received aldosterone antagonists compared to control, there were 72 fewer deaths from all causes per 1000 participants (95% CI 47 to 98) with a number needed to treat for an additional beneficial outcome (NNTB) of 14 (95% CI 10 to 21) and for gynaecomastia were 26 events per 1000 participants (95% CI 15 to 39) with a number need to treat for an additional harmful outcome (NNTH) of 38 (95% CI 26 to 68).

Authors' Conclusions: Based on moderate certainty of the evidence, aldosterone antagonists probably reduces the risk of all-cause and cardiovascular death and probably reduces morbidity due to cardiovascular and cerebrovascular disease in people with CKD requiring dialysis. For the adverse effect of gynaecomastia, the risk was increased compared to control. For this outcome, the absolute risk was lower than the absolute risk of death. It is hoped the three large ongoing studies will provide better certainty of evidence.
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http://dx.doi.org/10.1002/14651858.CD013109.pub2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8094170PMC
February 2021

Glycated albumin and hemoglobin A1c levels and cause-specific mortality by patients' conditions among hemodialysis patients with diabetes: a 3-year nationwide cohort study.

BMJ Open Diabetes Res Care 2020 10;8(1)

Committee of Renal Data Registry, Japanese Society for Dialysis Therapy, Tokyo, Japan.

Introduction: Differences in mortality and cause-specific mortality rates according to glycated albumin (GA) and hemoglobin A1c (HbA1c) levels among dialysis patients with diabetes based on hypoglycemic agent use and malnutrition status remain unclear. Here, we examine these associations using a nationwide cohort.

Research Design And Methods: We examined 40 417 dialysis patients with diabetes who met our inclusion criteria (female, 30.8%; mean age, 67.3±11.2 years; mean dialysis duration, 5.4±4.6 years). The Global Leadership Initiative on Malnutrition criteria were used to assess malnutrition. Adjusted HRs and 95% confidence limits were calculated for 3-year mortality after adjustment for 18 potential confounders. HRs and subdistribution HRs were used to explore cause-specific mortality.

Results: We found a linear association between 3-year mortality and GA levels only in patients with GA ≥18% and not in patients with low GA levels, with a U-shaped association between HbA1c levels and the lowest morality at an HbA1c 6.0%-6.3%. This association differed based on patient conditions and hypoglycemic agent use. If patients using hypoglycemic agents were malnourished, mortality was increased with GA ≥24% and HbA1c ≥8%. In addition, patients with GA ≥22% and HbA1c ≥7.6% had significantly higher infectious or cardiovascular mortality rates. On the other hand, an inverse association was found between GA or HbA1c levels and cancer mortality. Patients with GA ≤15.8% had a higher risk of cancer mortality, especially those not using hypoglycemic agents (HR 1.63 (1.00-2.66)).

Conclusions: Target GA and HbA1c levels in dialysis patients may differ according to hypoglycemic agent use, nutritional status, and the presence of cancer. The levels may be higher in malnourished patients than in other patients, and a very low GA level in dialysis patients not taking hypoglycemic agents may be associated with a risk of cancer.

Trial Registration Number: UMIN000018641.
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http://dx.doi.org/10.1136/bmjdrc-2020-001642DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7590349PMC
October 2020

Quantitative Anisotropic Analysis of Molecular Orientation in Amorphous NO at 6 K by Infrared Multiple-Angle Incidence Resolution Spectrometry.

J Phys Chem Lett 2020 Sep 8;11(18):7857-7866. Epub 2020 Sep 8.

Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.

The existence of molecular orientational order in nanometer-thick films of molecules has long been implied by surface potential measurements. However, direct quantitative determination of the molecular orientation is challenging, especially for metastable amorphous thin films at low temperatures. This study quantifies molecular orientation in amorphous NO at 6 K using infrared multiple-angle incidence resolution spectrometry (IR-MAIRS). The intensity ratio of the weak antisymmetric stretching vibration band of the NNO isotopomer between the in-plane and out-of-plane IR-MAIRS spectra provides an average molecular orientation angle of 65° from the surface normal. No discernible change is observed in the orientation angle when a different substrate material is used (Si and Ar) at 6 K or the Si substrate temperature is changed in the range of 6-14 K. This suggests that the transient mobility of NO during physisorption is key in governing the molecular orientation in amorphous NO.
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http://dx.doi.org/10.1021/acs.jpclett.0c01585DOI Listing
September 2020

In vivo characterization of the structures of films of a fatty acid and an alcohol adsorbed on the skin surface.

Biophys Chem 2020 11 18;266:106459. Epub 2020 Aug 18.

Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.

An in vivo analysis of stearyl alcohol and stearic acid films on the skin surface using polarized infrared-external reflection spectroscopy revealed that whether the sample molecules adopt an energetically stable conformation and orientation strongly depends on the molecular functionalities and sample preparation conditions. For stearic acid, even the difference in solute concentration between 0.1 and 0.5 wt% results in a different molecular conformation and orientation. This illustrates that the molecular organization of the adsorbate on the skin surface is sensitively determined by the kinetics of the sample film growth, not by the simple thermodynamic equilibrium with the skin temperature.
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http://dx.doi.org/10.1016/j.bpc.2020.106459DOI Listing
November 2020

Infrared active surface modes found in thin films of perfluoroalkanes reveal the dipole-dipole interaction and surface morphology.

J Chem Phys 2020 Jul;153(4):044703

Laboratory of Chemistry for Functionalized Surfaces, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan.

Infrared (IR) spectra of an organic thin film are mostly understood by considering the normal modes of a single molecule, if the dipole-dipole (D-D) interaction is ignorable in the film. When the molecules have a chemical group having a large permanent dipole moment such as the C=O and C-F groups, the D-D interaction induces vibrational couplings across the molecules, which produces an extra band as a surface phonon or polariton band because of the small thickness. Since the dipole moment of an organic compound is much less than that of an inorganic ionic crystal, we have a problem that the extra band looks like a normal-mode band, which are difficult to be discriminated from each other. In fact, this visual similarity sometimes leads us to a wrong direction in chemical discussion because the direction of the transition moment of the extra band is totally different from those of the normal modes. Here, we show useful selection rules for discussing IR spectra of a thin film without performing the permittivity analysis. The apparent change in the spectral shape on decrease in the thickness of the sample can be correlated with the morphological change in the film surface, which can also be discussed with changes in the molecular packing. This analytical technique has effectively been applied for studying the chemical properties of perfluoroalkanes as a chemical demonstration, which readily supports the stratified dipole-array theory for perfluoroalkyl compounds.
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http://dx.doi.org/10.1063/5.0012910DOI Listing
July 2020

Association of erythropoietin resistance and fibroblast growth factor 23 in dialysis patients: Results from the Japanese Dialysis Outcomes and Practice Patterns Study.

Nephrology (Carlton) 2021 Jan 20;26(1):46-53. Epub 2020 Aug 20.

Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Tokyo, Japan.

Background: Fibroblast growth factor 23 (FGF23) plays an important role in chronic kidney disease (CKD)-related mineral and bone disorders. High FGF23 levels are associated with increased risk of anaemia in non-haemodialysis CKD patients. FGF23 also negatively regulates erythropoiesis in mice. We hypothesized that higher FGF23 levels are associated with increased erythropoietin hyporesponsiveness among haemodialysis patients.

Methods: The study included 1044 patients from the Japanese Dialysis Outcomes and Practice Patterns Study (J-DOPPS) phase 5 (2012-2015). The outcome was erythropoiesis-stimulating agent hyporesponsiveness (ESA-hypo), defined as mean Hgb <10 g/dL and standardized mean ESA dose >6000 u/week over 4 months following FGF23 measurement. The association between ESA-hypo and FGF23 was estimated using multivariable-adjusted logistic generalized estimating equation regression models.

Results: Patients with higher levels of FGF23 were younger and had higher levels of serum albumin, creatinine, albumin-corrected calcium, phosphorus, PTH, 25(OH)-vitamin D, and had higher percentages of intravenous (IV) iron, IV vitamin D and cinacalcet use. ESA-hypo was present in 144 patients (13.8%). Compared with the third quintile of FGF23 levels, the odds ratio (95% CI) of ESA-hypo was 2.14 (0.99, 4.62) and 1.74 (0.74, 4.11) for the first and fifth quintiles, respectively.

Conclusion: The lowest and highest levels of FGF23 were associated with higher odds of ESA-hypo in patients on maintenance haemodialysis, although the associations were not statistically significant. The relationship between FGF23 and anaemia, and particularly the increased risks of ESA-hypo at low FGF23 levels which might be the result of energy saving, must be confirmed in larger clinical studies.
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http://dx.doi.org/10.1111/nep.13765DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7754421PMC
January 2021

Changes in Quality of Life in Older Hemodialysis Patients: A Cohort Study on Dialysis Outcomes and Practice Patterns.

Am J Nephrol 2020 31;51(8):650-658. Epub 2020 Jul 31.

Division of Nephrology and Endocrinology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan.

Background: Despite improvements in dialysis treatment, mortality rates remain high, especially among older hemodialysis patients. Quality of life (QOL) among hemodialysis patients is strongly associated with higher risk of death. This study aimed to describe the health-related QOL and its change in older maintenance hemodialysis patients and to demonstrate characteristics associated with health-related QOL.

Methods: Data on 892 maintenance hemodialysis patients aged 60 years or older who were surveyed using the Kidney Disease Quality of Life Short Form at baseline and 2 years after study enrollment in phases 4 (2009-2011) and 5 (2012-2014) of the Japanese Dialysis Outcomes and Practice Patterns Study were analyzed. We categorized participants into 3 age groups (60-69, 70-79, and ≥80 years) and described baseline physical component summary (PCS) and mental component summary (MCS) scores, as well as their distribution of changes after 2 years across each category.

Results: Hemodialysis patients aged 70-79 years and ≥80 years had lower PCS scores than those aged 60-69 years (median: 70-79 years = 43.1; interquartile range [IQR], 35.2-49.4; ≥80 years = 38.8; IQR, 31.6-43.8; 60-69 years = 45.4; IQR, 37.5-51.4; p < 0.001). In contrast, MCS scores did not significantly differ by age category (70-79 years = 45.6; IQR, 38.4-53.7; ≥80 years = 45.4; IQR, 36.9-55.1; 60-69 years = 46.8; IQR, 39.5-55.7; p = 0.1). As dialysis vintage lengthened, the PCS score significantly became lower, whereas no association was found with change in the MCS score. The MCS score declined over time in older patients, especially among those aged 80 years and older after 2 years' follow-up.

Conclusions: Physical QOL became worse as dialysis vintage lengthened. In contrast, mental QOL declined over time within a relatively short period among older maintenance hemodialysis patients.
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http://dx.doi.org/10.1159/000509309DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7592938PMC
July 2020

Supramolecular double-stranded Archimedean spirals and concentric toroids.

Nat Commun 2020 07 17;11(1):3578. Epub 2020 Jul 17.

Department of Materials Physics and Chemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka, 819-0395, Japan.

Connecting molecular-level phenomena to larger scales and, ultimately, to sophisticated molecular systems that resemble living systems remains a considerable challenge in supramolecular chemistry. To this end, molecular self-assembly at higher hierarchical levels has to be understood and controlled. Here, we report unusual self-assembled structures formed from a simple porphyrin derivative. Unexpectedly, this formed a one-dimensional (1D) supramolecular polymer that coiled to give an Archimedean spiral. Our analysis of the supramolecular polymerization by using mass-balance models suggested that the Archimedean spiral is formed at high concentrations of the monomer, whereas other aggregation types might form at low concentrations. Gratifyingly, we discovered that our porphyrin-based monomer formed supramolecular concentric toroids at low concentrations. Moreover, a mechanistic insight into the self-assembly process permitted a controlled synthesis of these concentric toroids. This study both illustrates the richness of self-assembled structures at higher levels of hierarchy and demonstrates a topological effect in noncovalent synthesis.
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http://dx.doi.org/10.1038/s41467-020-17356-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7368029PMC
July 2020

Simultaneous Analysis of Molecular Orientation and Quantity Change of Constituents in a Thin Film Using pMAIRS.

J Phys Chem A 2020 Apr 19;124(13):2714-2720. Epub 2020 Mar 19.

Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.

Spectral analysis using chemometrics is extensively used for quantitative chemical analysis in a mixture, but it works powerfully only when the peak intensity is solely proportional to the quantity of chemical components. In this sense, thin films on a solid substrate are not suitable for chemometric analysis, because the molecular orientation also influences the peak intensity via the surface selection rules. In the present study, this long-term analytical issue has readily been overcome by using p-polarized multiple-angle incidence resolution spectrometry (pMAIRS), which has a characteristic that the in-plane (IP) and out-of-plane (OP) vibrational spectra of a thin-film sample are obtained simultaneously in a common ordinate scale. Thanks to this unique power of pMAIRS, the average of the IP and OP spectra annihilates optical anisotropy, yielding an orientation-free spectrum, which enables us to perform the simultaneous quantitative analysis of both quantity change and molecular orientation of the constituents in a thin film. Now, we are ready to examine chemical reactions quantitatively in a thin film.
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http://dx.doi.org/10.1021/acs.jpca.0c00111DOI Listing
April 2020

Estimating the Fraction of First-Year Hemodialysis Deaths Attributable to Potentially Modifiable Risk Factors: Results from the DOPPS.

Clin Epidemiol 2020 16;12:51-60. Epub 2020 Jan 16.

Arbor Research Collaborative for Health, Ann Arbor, MI, USA.

Purpose: Mortality among first-year hemodialysis (HD) patients remains unacceptably high. To address this problem, we estimate the proportions of early HD deaths that are potentially preventable by modifying known risk factors.

Methods: We included 15,891 HD patients (within 60 days of starting HD) from 21 countries in the Dialysis Outcomes and Practice Patterns Study (1996-2015), a prospective cohort study. Using Cox regression adjusted for potential confounders, we estimated the fraction of first-year deaths attributable to one or more of twelve modifiable risk factors (the population attributable fraction, AF) identified from the published literature by comparing predicted survival based on risk factors observed vs counterfactually set to reference levels.

Results: The highest AFs were for catheter use (22%), albumin <3.5 g/dL (19%), and creatinine <6 mg/dL (12%). AFs were 5%-9% for no pre-HD nephrology care, no residual urine volume, systolic blood pressure <130 or ≥160 mm Hg, phosphorus <3.5 or ≥5.5 mg/dL, hemoglobin <10 or ≥12 g/dL, and white blood cell count >10,000/μL. AFs for ferritin, calcium, and PTH were <3%. Overall, 65% (95% CI: 59%-71%) of deaths were attributable to these 12 risk factors. Additionally, the AF for C-reactive protein >10 mg/L was 21% in facilities where it was routinely measured.

Conclusion: A substantial proportion of first-year HD deaths could be prevented by successfully modifying a few risk factors. Highest priorities should be decreasing catheter use and limiting malnutrition/inflammation whenever possible.
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http://dx.doi.org/10.2147/CLEP.S233197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6974411PMC
January 2020

Screening tool for identifying adults with excessive salt intake among community-dwelling adults: a population-based cohort study.

Am J Clin Nutr 2020 04;111(4):814-820

Center for Innovative Research for Communities and Clinical Excellence (CiRC2LE), Fukushima Medical University, Fukushima, Japan.

Background: Excessive salt intake is widely known to be a cause of hypertension, cardiovascular events, and so on. However, simple tools for screening excessive salt intake are lacking.

Objective: We aimed to develop a simple screening tool to identify community-dwelling adults with excessive salt intake.

Methods: The present study involved participants who received health check-ups in Fukushima, Japan, in 2016 and 2017. We defined data from the 2016 check-up as the derivation set, and data from those who received check-ups in 2017 but not 2016 as the validation set. The outcome measure was excessive salt intake, defined as the estimated daily salt intake of 1 SD or more. Candidate predictors associated with the outcome were extracted using the Delphi method by an expert panel and narrowed down with clinical expertise and stepwise backward selection. The screening tool was developed using a coefficient-based multivariable scoring method and externally validated.

Results: A total of 1101 participants were included in the derivation set and 249 in the validation set. At the conclusion of the deviation process, 8 predictors were selected and scored. The areas under the receiver operating characteristic curve for derivation and external validation were 0.70 (95% CI: 0.67, 0.74) and 0.71 (95% CI: 0.62, 0.80), respectively. The calibration slope and intercept for external validation were 1.16 and -0.03, respectively.

Conclusion: We developed a screening tool to identify adults with excessive salt intake. By extracting groups with excessive salt intake, target populations needing intervention for salt reduction can be highlighted efficiently.
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http://dx.doi.org/10.1093/ajcn/nqaa003DOI Listing
April 2020

Phthalimide-Based Transparent Electron-Transport Materials with Oriented-Amorphous Structures: Preparation from Solution-Processed Precursor Films.

Chempluschem 2019 Sep 26;84(9):1396-1404. Epub 2019 Jun 26.

Institute for Chemical Research, Kyoto University Uji, Kyoto, 611-0011, Japan.

A star-shaped molecule featuring three phthalimide units attached to a triazine core was designed as an electron-transport material. Solution processing was achieved by preparing a precursor molecule bearing tert-butoxycarbonyl (Boc) substituents, which are afterwards removed by annealing. The annealed film is transparent to visible light, with an absorption edge of 339 nm. Two-dimensional grazing incidence X-ray diffraction (2D-GIXD) and p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) measurements showed that the molecular orientation changed from random to face-on during the cleaving of Boc groups while keeping the overall crystallinity low. This "oriented-amorphous" structure is desirable for transport layers in devices such as organic light-emitting diodes (OLEDs) and solar cells.
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http://dx.doi.org/10.1002/cplu.201900274DOI Listing
September 2019

Noise Reduction in Solid-State NMR Spectra Using Principal Component Analysis.

J Phys Chem A 2019 Nov 13;123(47):10333-10338. Epub 2019 Nov 13.

Institute for Chemical Research , Kyoto University , Uji, Kyoto 611-0011 , Japan.

A noise reduction method was developed for solid-state nuclear magnetic resonance spectroscopy using multivariate analysis. Principal component analysis was first applied for cross-polarization/magic angle spinning and C spin-lattice relaxation measurements of solid-state nuclear magnetic resonance array spectra. The contact time of cross-polarization/magic angle spinning and the delay time in spin-lattice relaxation measurements were continuously changed to obtain a series of spectra, which were used for noise reduction using principal component analysis. The noise reduction method successfully produced spectra with improved signal-to-noise ratios. This noise reduction method shortens the measurement time and allows for detection of components with minute signals.
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http://dx.doi.org/10.1021/acs.jpca.9b04437DOI Listing
November 2019

Deficiency of Cardiac Natriuretic Peptide Signaling Promotes Peripartum Cardiomyopathy-Like Remodeling in the Mouse Heart.

Circulation 2020 02 31;141(7):571-588. Epub 2019 Oct 31.

National Cerebral and Cardiovascular Center (K.K.), Osaka, Japan.

Background: The maternal circulatory system and hormone balance both change dynamically during pregnancy, delivery, and the postpartum period. Although atrial natriuretic peptides and brain natriuretic peptides produced in the heart control circulatory homeostasis through their common receptor, NPR1, the physiologic and pathophysiologic roles of endogenous atrial natriuretic peptide/brain natriuretic peptide in the perinatal period are not fully understood.

Methods: To clarify the physiologic and pathophysiologic roles of the endogenous atrial natriuretic peptide/brain natriuretic peptide-NPR1 system during the perinatal period, the phenotype of female wild-type and conventional or tissue-specific Npr1-knockout mice during the perinatal period was examined, especially focusing on maternal heart weight, blood pressure, and cardiac function.

Results: In wild-type mice, lactation but not pregnancy induced reversible cardiac hypertrophy accompanied by increases in fetal cardiac gene mRNAs and ERK1/2 (extracellular signaling-regulated kinase) phosphorylation. Npr1-knockout mice exhibited significantly higher plasma aldosterone level than did wild-type mice, severe cardiac hypertrophy accompanied by fibrosis, and left ventricular dysfunction in the lactation period. Npr1-knockout mice showed a high mortality rate over consecutive pregnancy-lactation cycles. In the hearts of Npr1-knockout mice during or after the lactation period, an increase in interleukin-6 mRNA expression, phosphorylation of signal transducer and activator of transcription 3, and activation of the calcineurin-nuclear factor of the activated T cells pathway were observed. Pharmacologic inhibition of the mineralocorticoid receptor or neuron-specific deletion of the mineralocorticoid receptor gene significantly ameliorated cardiac hypertrophy in lactating Npr1-knockout mice. Anti-interleukin-6 receptor antibody administration tended to reduce cardiac hypertrophy in lactating Npr1-knockout mice.

Conclusions: These results suggest that the characteristics of lactation-induced cardiac hypertrophy in wild-type mice are different from exercise-induced cardiac hypertrophy, and that the endogenous atrial natriuretic peptide/brain natriuretic peptide-NPR1 system plays an important role in protecting the maternal heart from interleukin-6-induced inflammation and remodeling in the lactation period, a condition mimicking peripartum cardiomyopathy.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.119.039761DOI Listing
February 2020

Robust Surface Plasmon Resonance Chips for Repetitive and Accurate Analysis of Lignin-Peptide Interactions.

ACS Omega 2018 Jul 9;3(7):7483-7493. Epub 2018 Jul 9.

International Research Center for Elements Science, Institute for Chemical Research, Division of Environmental Chemistry, Institute for Chemical Research, and Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji 611-0011, Kyoto, Japan.

We have developed novel surface plasmon resonance (SPR) sensor chips whose surfaces bear newly synthesized functional self-assembled monolayer (SAM) anchoring lignin through covalent chemical bonds. The SPR sensor chips are remarkably robust and suitable for repetitive and accurate measurement of noncovalent lignin-peptide interactions, which is of significant interest in the chemical or biochemical conversion of renewable woody biomass to valuable chemical feedstocks. The lignin-anchored SAMs were prepared for the first time by click chemistry based on an azide-alkyne Huisgen cycloaddition: mixed SAMs are fabricated on gold thin film using a mixture of alkynyl and methyl thioalkyloligo(ethylene oxide) disulfides and then reacted with azidated milled wood lignins to furnish the functional SAMs anchoring lignins covalently. The resulting SAMs were characterized using infrared reflection-absorption, Raman, and X-ray photoelectron spectroscopies to confirm covalent immobilization of the lignins to the SAMs via triazole linkages and also to reveal that the SAM formation induces a helical conformation of the ethylene oxide chains. Further, SPR measurements of the noncovalent lignin-peptide interactions using lignin-binding peptides have demonstrated high reproducibility and durability of the prepared lignin-anchored sensor chips.
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http://dx.doi.org/10.1021/acsomega.8b01161DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6644341PMC
July 2018

Conformation change of α-synuclein(61-95) at the air-water interface and quantitative measurement of the tilt angle of the axis of its α-helix by multiple angle incidence resolution spectroscopy.

Colloids Surf B Biointerfaces 2019 Nov 29;183:110401. Epub 2019 Jul 29.

1301 Memorial Drive, Department of Chemistry, University of Miami, Coral Gables, FL, 33146, USA. Electronic address:

Various techniques have been developed to determine protein's structure to understand how proteins work.  Compared with X-ray crystallography requiring proteins to form single crystal structure and NMR which usually needs long time measurement, surface FT-IR techniques are able to quickly determine the tilt angle (the key information to determine whether the α-helix is transmembrane) of peptides/proteins in a monolayer at the interface (e.g. membranes). Specifically, for α-helical peptides/proteins in membrane, the tilt angle of the axis is one of the key information. In this paper, Multiple Angle Incidence Resolution Spectroscopy (MAIRS), a recently developed surface FTIR technique, was applied for the first time to quantitatively determine the tilt angle of the axis of α-helical model peptide related to α-synuclein (α-syn). α-Syn is a 140-amino-acid presynaptic protein whose aggregation is the hallmark of Parkinson's disease (PD). It is difficult for α-syn to form a single crystal structure and the primary structure of α-syn constitutes three domains: the N-terminus containing residues 1-60; the nonamyloid component (NAC) which spans residues 61-95 and is highly prone to aggregation; and C-terminus with residues 96-140. Here, the NAC part (i.e., α-syn(61-95)) responsible for the aggregation was found to change its unstructured conformation in aqueous solution to α-helix at the air-water interface by circular dichroism and MAIRS. In addition, the instinct power of MAIRS to quantitatively measure the tilt angle of the axis of α-helical α-syn(61-95) in monolayer was fully exhibited. Therefore, MAIRS is a potential supplemental technique to X-ray crystallography and NMR to determine the structure of membrane peptides/proteins.
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http://dx.doi.org/10.1016/j.colsurfb.2019.110401DOI Listing
November 2019

Second Generation of Multiple-Angle Incidence Resolution Spectrometry.

J Phys Chem A 2019 Aug 2;123(32):7177-7183. Epub 2019 Aug 2.

Laboratory of Chemistry for Functionalized Surfaces, Division of Environmental Chemistry, Institute for Chemical Research , Kyoto University , Gokasho, Uji , Kyoto 611-0011 , Japan.

Infrared surface spectroscopic techniques commonly have long-term issues that (1) the multiple reflections of light in the substrate yield optical interference fringes in the absorption spectrum and (2) the double modulation of light at the interferometer in a Fourier transform infrared spectrometer makes the water-vapor subtraction impossible. These measurement troubles often disturb the quantitative analysis of chemical bands of the analyte thin film. Multiple-angle incidence resolution spectrometry (MAIRS) is not an exception in this matter, either. In the present study, the long-term common issues have first been resolved by fixing the angle of incidence at a large angle, whereas the polarization angle is changed. With this simple conceptual change of MAIRS, as a result, we are ready for concentrating on spectral analysis only without concerning about the measurement troubles.
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http://dx.doi.org/10.1021/acs.jpca.9b05316DOI Listing
August 2019

External validation of the quick Sequential Organ Failure Assessment score for mortality and bacteraemia risk evaluation in Japanese patients undergoing haemodialysis: a retrospective multicentre cohort study.

BMJ Open 2019 07 11;9(7):e028856. Epub 2019 Jul 11.

Division of Nephrology, Department of Medicine, Showa University Fujigaoka Hospital, Yokohama, Japan.

Objectives: We aimed to examine the validity of the quick Sequential Organ Failure Assessment (qSOFA) score for mortality and bacteraemia risk assessment in Japanese haemodialysis patients.

Design: This is a retrospective multicentre cohort study.

Setting: The six participating hospitals are tertiary-care institutions that receive patients on an emergency basis and provide primary, secondary and tertiary care. The other participating hospital is a secondary-care institution that receives patients on an emergency basis and provides both primary and secondary care.

Participants: This study included haemodialysis outpatients admitted for bacteraemia suspicion, who had blood drawn for cultures within 48 hours of their initial admission.

Primary And Secondary Outcome Measures: The primary outcome measure was overall in-hospital mortality. Secondary outcomes included 28-day in-hospital mortality and the incidence of bacteraemia diagnosed based on blood culture findings. The discrimination, calibration and test performance of the qSOFA score were assessed. Missing data were handled using multiple imputation.

Results: Among the 507 haemodialysis patients admitted with bacteraemia suspicion between August 2011 and July 2013, the overall in-hospital mortality was 14.6% (74/507), the 28-day in-hospital mortality was 11.1% (56/507) and the incidence of bacteraemia, defined as a positive blood culture, was 13.4% (68/507). For predicting in-hospital mortality among haemodialysis patients, the area under the receiver operating characteristic curve was 0.61 (95% CI 0.56-0.67) for a qSOFA score ≥2. The Hosmer-Lemeshow χ statistics for the qSOFA score as a predictor of overall and 28-day in-hospital mortality were 5.72 (p=0.02) and 7.40 (p<0.01), respectively.

Conclusion: On external validation, the qSOFA score exhibited low diagnostic accuracy and miscalibration for in-hospital mortality and bacteraemia among haemodialysis patients.
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http://dx.doi.org/10.1136/bmjopen-2018-028856DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6629386PMC
July 2019

Long-Term Evaluation of Low-Dose Betamethasone for Ataxia Telangiectasia.

Pediatr Neurol 2019 11 13;100:60-66. Epub 2019 May 13.

Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University (TMDU), Tokyo, Japan. Electronic address:

Background: Ataxia telangiectasia is an autosomal recessive disorder characterized by cerebellar ataxia, telangiectases, immune defects, and a predisposition to malignancy. Quality of life is severely impaired by neurological symptoms. However, curative options for the neurological symptoms are limited. Recent studies have demonstrated short-term improvement in neurological symptoms with betamethasone therapy. However, the long-term and adverse effects of betamethasone are unclear. The aim of this study was to evaluate the long-term effects, benefits, and adverse effects of low-dose betamethasone in ataxia telangiectasia.

Methods: Six patients with ataxia telangiectasia received betamethasone at 0.02 mg/kg/day for two years. After cessation of betamethasone, the patients were observed for two additional years. Neurological assessments were performed, and adverse effects were monitored every three months throughout the four-year study period.

Results: Transient improvement of neurological symptom was observed in five of the six patients. However, after two years betamethasone treatment, only one of the six patients showed a slight improvement in the neurological score, one patient showed no change, and the neurological scores of the remaining four patients deteriorated. After the cessation of betamethasone treatment, neurological symptoms worsened in all patients. As an adverse effect of betamethasone, transient adrenal dysfunction was observed in all cases.

Conclusions: Although these findings are in agreement with previous studies suggesting that short-term betamethasone treatment transiently benefits patients with ataxia telangiectasia, the long-term benefits and risks should be carefully considered.
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http://dx.doi.org/10.1016/j.pediatrneurol.2019.05.006DOI Listing
November 2019

Salt intake and body weight correlate with higher blood pressure in the very elderly population: The Sukagawa study.

J Clin Hypertens (Greenwich) 2019 07 26;21(7):942-949. Epub 2019 Jun 26.

Center for Innovative Research for Communities and Clinical Excellence (CiRC2LE), Fukushima Medical University, Fukushima, Japan.

As few epidemiological studies have investigated the effect of lifestyle factors on hypertension in the very elderly population, we conducted a cross-sectional study to examine the association of estimated salt intake and body weight with blood pressure in the very elderly population. We enrolled 288 participants aged 75 years or older who were residents of Sukagawa City, Fukushima Prefecture, Japan, who attended the health checkup conducted in 2015. Salt intake was estimated from spot urine samples using the Tanaka method. The mean values for age, estimated salt intake, and body weight of all participants were 79.7 years, 9.1 g/d (standard deviation 2.4 g), and 54.3 kg (standard deviation 10.2 kg), respectively. General linear models showed that salt intake and body weight were associated with higher systolic blood pressure (SBP) levels (per standard deviation higher level, adjusted difference 4.13 mm Hg [95% confidence interval 1.69-6.57] and 5.34 mm Hg [95% confidence interval 2.12-8.56], respectively). Body weight was associated with higher diastolic blood pressure (DBP) levels (per standard deviation higher level, 2.74 mm Hg [95% confidence interval 0.58-4.90]). However, salt intake was not associated with higher diastolic blood pressure levels (per standard deviation higher level, 1.15 mm Hg [95% confidence interval -0.49 to 2.79]). Our findings suggest that higher SBP is associated with both salt intake and body weight and that higher DBP is associated with body weight in the very elderly population. This study provides a rationale for lifestyle modifications to prevent hypertension as a population approach.
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http://dx.doi.org/10.1111/jch.13593DOI Listing
July 2019

Probing the Molecular Structure and Orientation of the Leaf Surface of Brassica oleracea L. by Polarization Modulation-Infrared Reflection-Absorption Spectroscopy.

Plant Cell Physiol 2019 Jul;60(7):1567-1580

Laboratory of Chemistry for Functionalized Surfaces, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, Japan.

The surface of most aerial plant organs is covered with the cuticle, a membrane consisting of a variety of organic compounds, including waxes, cutin (a polyester) and polysaccharides. The cuticle serves as the multifunctional interface between the plant and the environment, and plays a major role in protecting plants against various environmental stress factors. Characterization of the molecular arrangements in the intact cuticle is critical for the fundamental understanding of its physicochemical properties; however, this analysis remains technically challenging. Here, we describe the nondestructive characterization of the intact cuticle of Brassica oleracea L. leaves using polarization modulation-infrared (IR) reflection-absorption spectroscopy (PM-IRRAS). PM-IRRAS has a probing depth of less than several hundreds of nanometers, and reveals the crystalline structure of the wax covering the cuticle surface (epicuticular wax) and the nonhydrogen-bonding character of cutin. Combined analysis using attenuated total reflection-IR spectra suggested that hemicelluloses xylan and xyloglucan are present in the outer cuticle region close to the epicuticular wax, whereas pectins are dominant in the inner cuticle region (depth of ≤2 μm). PM-IRRAS can also determine the average orientation of the cuticular molecules, as indicated by the positive and negative spectral peaks. This unique advantage reveals the orientational order in the intact cuticle; the hydrocarbon chains of the epicuticular wax and cutin and the backbones of hemicelluloses are oriented perpendicular to the leaf surface. PM-IRRAS is a versatile, informative and easy-to-use technique for studying plant cuticles because it is nondestructive and does not require sample pretreatment and background measurements.
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http://dx.doi.org/10.1093/pcp/pcz063DOI Listing
July 2019

Rational Method of Monitoring Molecular Transformations on Metal-Oxide Nanowire Surfaces.

Nano Lett 2019 04 26;19(4):2443-2449. Epub 2019 Mar 26.

Interdisciplinary Graduate School of Engineering Sciences , Kyushu University , 6-1 Kasuga-Koen , Kasuga , Fukuoka 816-8580 , Japan.

Metal-oxide nanowires have demonstrated excellent capability in the electrical detection of various molecules based on their material robustness in liquid and air environments. Although the surface structure of the nanowires essentially determines their interaction with adsorbed molecules, understanding the correlation between an oxide nanowire surface and an adsorbed molecule is still a major challenge. Herein, we propose a rational methodology to obtain this information for low-density molecules adsorbed on metal oxide nanowire surfaces by employing infrared p-polarized multiple-angle incidence resolution spectroscopy and temperature-programmed desorption/gas chromatography-mass spectrometry. As a model system, we studied the surface chemical transformation of an aldehyde (nonanal, a cancer biomarker in breath) on single-crystalline ZnO nanowires. We found that a slight surface reconstruction, induced by the thermal pretreatment, determines the surface chemical reactivity of nonanal. The present results show that the observed surface reaction trend can be interpreted in terms of the density of Zn ions exposed on the nanowire surface and of their corresponding spatial arrangement on the surface, which promotes the reaction between neighboring adsorbed molecules. The proposed methodology will support a better understanding of complex molecular transformations on various nanostructured metal-oxide surfaces.
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http://dx.doi.org/10.1021/acs.nanolett.8b05180DOI Listing
April 2019

Influence of Alkoxy Chain Length on the Properties of Two-Dimensionally Expanded Azulene-Core-Based Hole-Transporting Materials for Efficient Perovskite Solar Cells.

Chemistry 2019 May 29;25(27):6741-6752. Epub 2019 Mar 29.

Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan.

A series of two-dimensionally expanded azulene-core-based π systems have been synthesized with different alkyl chain lengths in the alkoxy moieties connected to the partially oxygen-bridged triarylamine skeletons. The thermal, photophysical, and electronic properties of each compound were evaluated to determine the influence of the alkyl chain length on their effectiveness as hole-transporting materials (HTMs) in perovskite solar cells (PSCs). All the synthesized molecules showed promising material properties, including high solubility, the formation of flat and amorphous films, and optimal alignment of energy levels with perovskites. In particular, the derivatives with methyl and n-butyl in the side chains retained amorphous stability up to 233 and 159 °C, respectively. Such short alkoxy chains also resulted in improved electrical device properties. The PSC device fabricated with the HTM with n-butyl side chains showed the best performance with a power conversion efficiency of 18.9 %, which compares favorably with that of spiro-OMeTAD-based PSCs (spiro-OMeTAD=2,2',7,7'-tetrakis[N,N-bis(p-methoxyphenyl)amino]-9,9'-spirobifluorene).
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http://dx.doi.org/10.1002/chem.201806317DOI Listing
May 2019

Alternative Face-on Thin Film Structure of Pentacene.

Sci Rep 2019 Jan 24;9(1):579. Epub 2019 Jan 24.

Laboratory of Chemistry for Functionalized Surfaces, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.

Pentacene attracts a great deal of attention as a basic material used in organic thin-film transistors for many years. Pentacene is known to form a highly ordered structure in a thin film, in which the molecular long axis aligns perpendicularly to the substrate surface, i.e., end-on orientation. On the other hand, the face-on oriented thin film, where the molecular plane is parallel to the substrate, has never been found on an inert substrate represented by SiO. As a result, the face-on orientation has long been believed to be generated only on specific substrates such as a metal single crystal. In the present study, the face-on orientation grown on a SiO surface has first been identified by means of visible and infrared p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) together with two-dimensional grazing incidence X-ray diffraction (2D-GIXD). The combination of the multiple techniques readily reveals that the face-on phase is definitely realized as the dominant component. The face-on film is obtained when the film growth is kinetically restricted to be prevented from transforming into the thermodynamically stable structure, i.e., the end-on orientation. This concept is useful for controlling the molecular orientation in general organic semiconductor thin films.
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http://dx.doi.org/10.1038/s41598-018-37166-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6345764PMC
January 2019

Raman Optical Activity on a Solid Sample: Identification of Atropisomers of Perfluoroalkyl Chains Having a Helical Conformation and No Chiral Center.

J Phys Chem A 2019 May 27;123(18):3985-3991. Epub 2019 Mar 27.

Laboratory of Chemistry for Functionalized Surfaces, Division of Environmental Chemistry, Institute for Chemical Research , Kyoto University , Gokasho, Uji , Kyoto 611-0011 , Japan.

Perfluoroalkyl (R) chains have a specific helical conformation due to the steric repulsion between the adjacent CF units. Although R chains have no chiral center, two chiral structures, i.e., the right-handed (R) and left-handed (L) helices, are available as the most stable conformations, which are atropisomers to each other. According to the stratified dipole array (SDA) theory, the helical structure about the chain axis plays a key role in the spontaneous molecular aggregation of R chains in a two-dimensional manner, and the R chains having the same chirality tend to be aggregated spontaneously to generate molecular domains. This implies that an R compound in a solid state should be a mixture of the R and L domains, and each domain should exhibit distinguishable optical activity. To identify molecular domains with different atropisomers, in this study, Raman optical activity (ROA) measurements were performed on a Raman imaging spectrometer. Through the ROA measurements of recrystallized solid samples of an R compound, each particle exhibits an apparent optical activity, and the two atropisomers were readily distinguished. As a result, an R compound with the same helicity is found to be spontaneously aggregated as expected by the SDA theory.
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http://dx.doi.org/10.1021/acs.jpca.8b11613DOI Listing
May 2019