Biomedical subjects

Yuka Kobayashi

Publications and source records attributed to Yuka Kobayashi.

At least 19 recordsLinked to original sources

PubMed2007

Two-component supramolecular helical architectures: creation of tunable dissymmetric cavities for the inclusion and chiral recognition of the third components.

The inclusion and chiral recognition of racemic arylalkanols by supramolecular helical architectures consisting of enantiopure primary amines and achiral carboxylic acids were thoroughly studied. Among the architectures examined, a supramolecular helical architecture composed of the salt of enantiopure erythro-2-amino-1,2-diphenylethanol (1 b) and benzoic acid (2 a) was found to include a wide variety of racemic arylalkanols with recognition of their chirality. The helical architecture gave a dissymmetric 1D groove in the salt crystal, and the arylalkanols were enantioselectively included in the groove. The size and shape of the groove were tunable by proper selection of the achiral carboxylic acid component. The origin of the chiral recognition with the combination 1 b/2 a is discussed on the basis of X-ray crystallographic analyses.

Journal Article↗

PubMed2006

Structural relaxation in amorphous 1,2-dichloroethane studied by transformation between conformation isomers.

Structural relaxation in amorphous 1,2-dichloroethane (DCE) samples prepared by vapor deposition on cold substrates were studied by Raman scattering. The gauche and trans molecules of DCE were found to coexist in amorphous states immediately after the deposition, and structural relaxation occurred with temperature elevation before crystallization. Mole fraction of the gauche isomer increased during this relaxation process, although trans is the stable isomer in gaseous and crystalline states. At the final amorphous stage immediately before crystallization, the gauche mole fraction was close to the mole fraction of the supercooled liquid state. It was also found that trans molecules located at positions with lower density were more easily transformed into the gauche conformation, while the distribution of the local structure around the resultant gauche molecules remained almost unchanged during the structural relaxation. Such behaviors of amorphous DCE are discussed from the viewpoint of the characteristic molecular structure of DCE.

Journal Article↗

PubMed2006

Photochemical electron transfer through [corrected] the interface of hybrid films of titania nano-sheets and mono-dispersed spherical mesoporous silica particles.

Photochemical Electron Transfer (ET) between an organic dye, the porphyrin derivative TMPyP, and an electron acceptor, methyl viologen MV2+, have been investigated at the interface of two different inorganic films, i.e., layered titania nano-sheets (TNS) and a monolayer film of spherical and mono-dispersed mesoporous silica (sMPS) particles (ca. 0.5 microm). TMPyP ions were intercalated within the sMPS nano-cavities to form (TMPyP-sMPS) while MV2+ ions were intercalated into the TNS interlayers to form (MV2+-TNS). The (TMPyP-sMPS) and (MV2+-TNS) films were then stacked on a silica substrate in this order to form a (MV2+-TNS)/(TMPyP-sMPS) film and, upon UV light irradiation, ET could be induced. However, when this film was stacked inversely, i.e., for the (TMPyP-sMPS)/(MV2+-TNS) films on a silica substrate, no photoinduced ET were observed. Interestingly, however, even for this photo-inactive inversely stacked film, ET could be generated by inserting a gold vapor-deposited layer between the (MV2+-TNS) and (TMPyP-sMPS) films. The conjugation conditions at the interface of the inversely stacked (TMPyP-sMPS)/(MV2+-TNS) hybrid film were, thus, confirmed to strongly affect the photoinduced electron transfers and their efficiencies.

Biocompatible Materials↗

PubMed2006

Enantiopure O-substituted phenylphosphonothioic acids: chiral recognition ability during salt crystallization and chiral recognition mechanism.

[structure: see text] The chiral recognition ability of enantiopure O-methyl, O-ethyl, O-propyl, and O-phenyl phenylphosphonothioic acids (1a-d) for various kinds of racemic amines during salt crystallization and the chiral recognition mechanism were thoroughly investigated. The chiral recognition abilities of enantiopure 1a-d for a wide variety of racemic amines varied in a range of 6 to >99% enantiomeric selectivity. Deposited less-soluble diastereomeric salts were classified into two categories, prism- and needle-type crystals; the prism-type crystals were composed of a globular molecular cluster, while there existed a 2(1) column in the needle-type crystals. In contrast to a general observation of a similar 2(1) column in the less-soluble diastereomeric salt crystals of chiral primary amines with chiral carboxylic acids, the globular molecular cluster is a very unique hydrogen-bonding motif that has never been constructed in diastereomeric salt crystals. Excellent chiral recognition was always achieved when the less-soluble diastereomeric salts were prism-type crystals. Significant correlations were found between the degree of the chiral recognition with 1a-d, the crystal shape of the less-soluble diastereomeric salts, and the hydrogen-bonding motif (molecular cluster/2(1) column). The chiral recognition mechanisms via the molecular cluster and the 2(1) column formations are discussed in detail on the basis of X-ray crystallographic analyses.

Journal Article↗

PubMed2006

Effects of web-based supervisor training on job stressors and psychological distress among workers: a workplace-based randomized controlled trial.

Using workplaces as a unit for randomization, a randomized controlled trial was conducted to determine the effects of web-based supervisor training on the subject of worksite mental health on job stressors, supervisor support and psychological distress among subordinate workers. A total of eight workplaces of a sales and service company were randomly assigned to either training workplaces or non-training workplaces. Supervisors (n=23) at the training workplaces participated in web-based self-learning training on worksite mental health; supervisors (n=23) at the non-training workplaces did not. A total of 81 subordinate workers under the trained supervisors (the intervention group) and 108 subordinate workers under the non-trained supervisors (the control group) completed the Brief Job Stress Questionnaire (BJSQ) at baseline and at a three-month follow-up. No significant intervention effect was observed for any scale of the BJSQ measuring job stressors, supervisor or coworker support, or psychological distress among subordinate workers (p<0.05). The item score of work autonomy changed very little in the intervention group, while it decreased in the control group during the follow-up period, yielding a significant intervention effect (p=0.02). The item score for a friendly atmosphere in the workplace increased in the intervention group, while the score remained stable in the control group, yielding a significant intervention effect (p=0.02). While the present study failed to show any clear effect of the web-based training of supervisors on reduction of job stressors, it may be useful for maintaining worker autonomy and improving the friendliness of the worksite atmosphere.

Female↗

PubMed2006

[A case of recurrent esophageal cancer with lung metastases successfully treated with docetaxel-combination chemotherapy].

We report a case of a 67-year-old woman diagnosed with advanced esophageal cancer. She was treated with chemo-radiotherapy (5-FU/CDDP therapy and irradiation) initially, and primary lesion was well controlled. Two and a half years after first treatment, a chest CT showed multiple lung metastasis, which were confirmed by thoraco-laparoscopy. We chose docetaxel/CDDP combination chemotherapy, because of severe side effects due to the first treatment. After 3 courses, lung metastatic lesions were reduced. The following courses combining docetaxel-nedaplatin were done as ambulatory treatment. These regimens could be one choice for recurrent esophageal cancer, especially FP therapy-resistant or intolerant cases.

Aged↗

PubMed2005

Job strain and sick leave among Japanese employees: a longitudinal study.

OBJECTIVES: The present study is an investigation of the association between job stress, determined on the basis of a demand-control model or worksite social support at the baseline, and absence due to illness among employed Japanese males and females. METHODS: We analyzed 448 male and 81 female subjects who had taken no sick leave in the year preceding the baseline (1997) and observed them all until 1999. A self-administered questionnaire was the source information collected. It consisted of questions on socio-demographic variables, occupations, health-related behavior, a Japanese version of the Job Content Questionnaire, and the number of absences in the year preceding both the baseline and follow-up. Logistic regression analyses were used to determine how the characteristics of a job at the baseline affected sickness absence of 5 days or longer per year; controls were established for the gender, age, level of education completed, occupation, number of cigarettes smoked daily, and the amount of alcohol consumed weekly. RESULTS: Compared to the lowest tertile of the ratio of demand to control (job strain), the highest tertile was significantly associated with an increased risk of sickness absence of 5 days or longer per year (odds ratio 3.02; 95%CI 1.00-9.16) at follow-up. The dose-response relationship was supported (p for trend <0.05). However, individual variables of job demand, job control, and worksite social support were not significantly associated with the risk of absence from illness. CONCLUSIONS: The study provided prospective evidence that job strain leads to an increased risk of sick leave among Japanese employees.

Adult↗

PubMed2005

Periodic ab initio approach for the cooperative effect of CH/pi interaction in crystals: relative energy of CH/pi and hydrogen-bonding interactions.

The bonding property of the CH/pi interaction in organic crystals has been investigated by the means of a periodic ab initio method. The energy of the CH(sp(2))/pi interaction in crystals, estimated with periodic RHF/6-21G*, showed a reasonable attractive CH(sp(2))/pi interaction owing to a cooperative effect, whereas the results calculated with RHF/cc-pVDZ indicate a negligibly small or repulsive interaction. The relative contribution of the CH(sp(2))/pi interaction to the column packing energy was found to be roughly half of the energy of a conventional hydrogen bond. The calculation of the charge distributions on the aromatic rings participating in the CH(sp(2))/pi interaction in crystals revealed that the atoms were more ionic than those in the gas phase. These theoretical calculations suggest a hydrogen-bonding characteristic for the CH(sp(2))/pi interaction in crystals, which does not occur in solution nor gas phase. We present computational evidence of the existence of the cooperative effect of CH(sp(2))/pi interaction in crystals.

Journal Article↗

PubMed2005

Analysis of the carbohydrate binding specificity of the mushroom Pleurotus ostreatus lectin by surface plasmon resonance.

The sugar binding specificity of the mushroom Pleurotus ostreatus lectin (POL) was analyzed by surface plasmon resonance. The lectin was immobilized to a sensor chip, and asialo-bovine submaxillary mucin (asialo-BSM), one of the most potent inhibitors in the hemagglutination inhibition assay, tightly bound to the lectin. The binding specificity of various mono- or oligosaccharides to the lectin was evaluated by the coinjection method. The dissociation of asialo-BSM was promoted by injection of some haptenic saccharides. For the most part, the order of acceleration ability of the sugars to the dissociation in the coinjection experiment agreed with that of the inhibitory potency of each sugar evaluated by the hemagglutination inhibition assay. In conclusion, POL recognized a galactosyl residue, and the specificity was increased by substitution at the C-2 position of the galactosyl residue with a fucosyl or acetylamino group. This method using the coinjection method proved useful in analysis of carbohydrate-lectin binding specificity.

Asialoglycoproteins↗

PubMed2005

Synthesis, absolute configuration, and application of enantiopure trans-1-aminobenz[f]indan-2-ol.

Both novel enantiopure trans-1-aminobenz[f]indan-2-ols (4) were obtained from the racemate by the diastereomeric salt formation with (+)- and (-)-dibenzoyltartaric acids (8), respectively, and the absolute configuration of the enantiomer 4 in the less-soluble diastereomeric salt of racemic 4 with (+)-8 was determined to be (1S,2S) by an X-ray crystallographic analysis. The chiral recognition ability of the enantiopure amino alcohol was examined for the enantioseparation of racemic 2-arylalkanoic acids by the diastereomeric salt formation. The role of the naphthylene group of the amino alcohol was found to be closely associated with the stabilization of the crystal by CH/pi interactions on the basis of an X-ray crystallographic study.

Amino Alcohols↗

PubMed2005

Impaired gastric motility and its relationship to gastrointestinal symptoms in patients with chronic renal failure.

BACKGROUND: Gastrointestinal (GI) symptoms are common in patients with chronic renal failure (CRF), but the pathogenesis of these symptoms is unclear. Gastric motor function in CRF patients remains controversial, and the correlation between GI symptoms and gastric motility is also unclear. The aim of this study was to elucidate the relationship between gastric motility and GI symptoms in patients with CRF. METHODS: Gastric motility was evaluated with cutaneously recorded electrogastrographs (EGGs) and gastric emptying of a solid meal, using 13C-octanoic acid breath testing, in 21 patients with predialysis endstage CRF and in 21 matched healthy controls. GI symptom severity was quantified in all patients. RESULTS: The CRF patients had a significantly lower incidence of normogastria postprandially and a lower power ratio than did healthy controls on the EGGs, with the CRF patients showing delayed gastric emptying. Three patients with normal gastric motility had no GI symptoms, and ten patients with both abnormal EGG and delayed gastric emptying had significantly higher GI symptom scores than the patients without abnormalities. CONCLUSIONS: The patients with CRF showed gastric hypomotility, including impaired gastric myoelectrical activity and delayed gastric emptying. Gastric hypomotility appears to be an important factor in the generation of GI symptoms in patients with CRF.

Adult↗

PubMed2005

Effects of web-based supervisor training on supervisor support and psychological distress among workers: a randomized controlled trial.

BACKGROUND: A randomized controlled trial was conducted to determine the effects of web-based supervisor training on worksite mental health on supervisor support and psychological distress among subordinate workers. METHODS: Section chiefs in a computer engineering company were randomly assigned to either a training group (n = 9) or a non-training group (n = 7). The section chiefs in the training group participated in web-based self-learning training on worksite mental health. A total of 92 subordinate workers under the trained section chiefs (the intervention group) and 84 subordinate workers under the untrained section chiefs (the control group) completed a questionnaire at baseline and a 3-month follow-up. RESULTS: The score of supervisor support greatly decreased in the control group during the follow-up period, and the score changed very little in the intervention group, with a significant intervention effect (P = 0.032). This pattern was more pronounced for one particular item dealing with the extent to which a supervisor listens to personal problems of subordinate workers (the intervention effect, P = 0.012). No intervention effect was observed for the score measuring co-worker support, psychological distress, or other job stressors among subordinate workers (P > 0.05). CONCLUSIONS: It is suggested that the web-based training of supervisors on worksite mental health is useful in improving, or at least maintaining, supervisor support among subordinate workers.

Adult↗

PubMed2005

DPPH radical-scavenging effect of several phenylpropanoid compounds and their glycoside derivatives.

Eugenol, isoeugenol, caffeic acid, ferulic acid, isoferulic acid, estragole, trans-anethole, and paeonol are components of a Chinese herbal medicine used as a painkiller and stomachic. We investigated the potential role of these compounds as antioxidants. We studied the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging effect of these molecules, together with some glycoside derivatives, to ascertain their potential in reducing the levels of activated oxygen species in vivo. The DPPH radical-scavenging effects of eugenol, isoeugenol, and the glycoside derivatives of caffeic acid, ferulic acid, and isoferulic acid (SC(50)=8-28 microM) were similar to those of alpha-tocopherol, which was used as a positive control.

Antioxidants↗

PubMed2005

Relationship between two job stress models and coronary risk factors among Japanese part-time female employees of a retail company.

The objective of this study was to explore the associations between two major job stress models (job strain and effort-reward imbalance) and coronary heart disease (CHD) risk factors (blood pressure; total, high- (HDL) and low-density lipoprotein (LDL) cholesterol; and triglycerides) in Japanese part-time female employees of a retail company. The study population was either 35 yr old or between 40 and 63 yr old. Data collection was carried out in 2002; a total of 1,401 subjects participated in a medical examination and completed a questionnaire. After adjusting for other covariates (age, relative weight, tobacco use, alcohol consumption, lack of exercise, education, marital status, history of child bearing, medical treatment for disease, and occupation), a significant association was found between the effort-reward imbalance, a "high-cost and low-gain" condition at work, and a high prevalence of low HDL cholesterol (Odds ratio=4.4). A weak but unexpected association was found between job strain and low prevalence of low HDL cholesterol. In explanatory analysis with individual components of the two models, associations were evident between high extrinsic effort and high prevalence of low HDL cholesterol and low prevalence of high triglyceride, high job control and low prevalence of high systolic blood pressure, and high job demands and low prevalence of high systolic and diastolic blood pressure. In this cross-sectional study of Japanese part-time working women, a significant association was found between effort-reward imbalance and unfavorable HDL cholesterol profiles. The findings did not support the hypothesis that job strain is associated with CHD risk factors.

Adult↗

PubMed2005

[Development of a checklist for evaluation of mental health activities at the workplace].

"The Checklist for Evaluation of Mental Health Activities at the Workplace" was developed for workplace staff evaluating mental health activities in their own workplace. The validity and reliability of the checklist were examined and criteria for evaluation were developed for workplace/organization/companies with 50 or more employees in Japan. The checklist initially included 33 items covering seven major domains of occupational mental health, with a four-point response option, based on the Japanese Guideline for Worker Mental Health in the Workplace and a relevant literature review. A questionnaire was send to 60 members of the Occupational Mental Health Committee (OMHC) of the Japan Society for Occupational Health to ask their opinions on the checklist and on the minimum requirement for each item on the checklist; 30 (50%) responded. A random sample of 1,335 workplaces from a contractor list of workplaces for worker compensation insurance and a questionnaire was send to the personnel department to fill in the checklist; 412 (31.5%) responded and data from 335 of them with 50 or more employees were analyzed. Some OMHC members felt that one of the items (concerning the Total Health Promotion program) should be dropped; thus the checklist was revised to include 32 items, still covering the seven domains. Based on the workplace survey data, most domain scales showed internal consistency reliability at an acceptable level; explanatory factor analysis yielded a four-factor structure that was well concordant with the hypnotized seven-domain structure. Three levels of adequacy of mental health activities were set for each domain scale: "red" (inadequate), "yellow" (minimal), and "green" (adequate). One third of occupational health professionals from 49 workplaces rated the evaluation result based on the checklist as concordant with their view; 95% of them said the checklist would be useful in promoting occupational mental health activities. The study indicated that the checklist had reliability (based on internal consistency reliability) and content- and construct-validity (based on expert opinions, a factor-structure concordant with empirical data, and evaluation by workplace staff). The checklist seems useful in promoting occupational mental health activities.

Counseling↗

PubMed2004

A new hydrogen-bonding motif for chiral recognition in the diastereomeric salts of racemic 1-phenylethylamine derivatives with enantiopure O-ethyl phenylphosphonothioic acid.

An enantiopure phosphonothioic acid showed a unique and superior chiral recognition ability, arising from its P-stereogenicity, for racemic 1-phenylethylamine derivatives through diastereomeric crystallization. Spherical molecular clusters, associated by hydrogen bonds and CH/pi interactions, aggregated with high symmetry in the less-soluble diastereomeric salts.

Journal Article↗

PubMed2004

Rational design of CH/pi interaction sites in a basic resolving agent.

A novel synthetic basic resolving agent, cis-1-aminobenz[f]indan-2-ol (ABI), was rationally designed by introducing effective CH/pi interaction sites to cis-1-aminoindan-2-ol (AI), whose chiral recognition ability has been reported from our laboratory. ABI was applicable to a wide variety of racemic arylalkanoic acids and showed moderate to excellent chiral recognition ability, which was obviously higher than that of AI. The fundamental and important role of CH/pi interactions, such as tunable CH(sp(2))/pi and CH(sp(3))/pi interactions, in the chiral recognition by ABI was revealed by X-ray crystallographic study.

Journal Article↗

PubMed2004

Purification, characterization, and sugar binding specificity of an N-Glycolylneuraminic acid-specific lectin from the mushroom Chlorophyllum molybdites.

A carbohydrate-binding protein was isolated from the carpophores of the mushrooms and designated the Chlorophyllum molybdites lectin (CML) based on its origin. The molecular mass of CML was 32 kDa, and it was composed of two 16-kDa monomers with no disulfide bonds. Monosaccharide analysis indicated that 12% of the mass of CML was carbohydrate and consisted of GlcNAc:GalNAc:Gal:Man:l-Fuc in a molar ratio of 1.5:1.9: 4.4:4.8:1.0. In the hemagglutination inhibition assay, CML exhibited the strongest binding specificity toward N-glycolylneuraminic acid (NeuGc) among the monosaccharides tested, whereas NeuAc did not inhibit the hemagglutination at all. GalNAc and Mealpha-GalNAc were also inhibitory at much higher concentrations than NeuGc. Among the glycoproteins, asialobovine submaxillary mucin (BSM) and porcine stomach mucin (PSM) showed strong inhibitory effects. In surface plasmon resonance analysis, asialo-BSM and PSM exhibited the strongest binding affinity. After co-injection of CML and NeuGc or GalNAc onto the asialo-BSM- or PSM-immobilized chip, the dissociation of CML from the immobilized PSM was accelerated by NeuGc and GalNAc, but the dissociation of CML from the immobilized asialo-BSM was only promoted by GalNAc. These results and the other surface plasmon resonance experiments allowed us to conclude that the binding of asialo-BSM to CML was because of an interaction between the lectin and the GalNAc residues of asialo-BSM, and both the NeuGc and GalNAc residues were responsible for the binding of PSM to CML. The results also suggested that CML had two different carbohydrate binding domains, one specific for NeuGc and the other for GalNAc.

Agaricales↗