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Biomedical subjects

S Yagi

Publications and source records attributed to S Yagi.

At least 19 recordsLinked to original sources
PubMed2006

Global tuning of local molecular phenomena: an alternative approach to bionanoelectronics.

We have applied simultaneous horizontal and vertical bias to a single molecule (2 nm(2)) in an ordered and disordered matrix to virtually isolate and tune its property without taking it out physically from its environment. Using a dedicated electrode system, we have locally tuned nanoscale properties vertically by STM, while stabilizing its environment by applying a global electric field horizontally. Using this technique, we report tuning of molecular conformations in room temperature, whose evolution of states has been statistically investigated. We have also shown control on switching of a few selected conformations by applying dual bias simultaneously. As we avoid any direct injection of charge into the system via electrode contact, this technique could be used as a generalized method to tune phenomena evolved in an environment of weak interaction from a large distance without destroying the property.

Electrochemistry↗
PubMed2006

The alpha2 type IX collagen tryptophan polymorphism is associated with the severity of disc degeneration in younger patients with herniated nucleus pulposus of the lumbar spine.

Tryptophan alleles in COL9A2 (Trp2) and COL9A3 (Trp3) have been linked to lumbar disc diseases in the Finnish population. Although such diseases consist of various pathogenetically different conditions, detailed analysis of each has not been well documented. The aim of this study was to clarify whether the collagen IX tryptophan alleles influence the symptomatic degeneration of the lumbar disc in Japanese patients with herniated nucleus pulposus. We performed a prospective study of 84 patients who underwent lumbar discectomy. The degree of disc degeneration was evaluated by magnetic resonance images in relation to the collagen IX genotype. Twenty patients (21.4%) had the Trp2 allele and no patients had the Trp3 allele. Patients under 40 years with the Trp2 allele showed more severe disc degeneration at the surgical level than did those without the Trp2 allele (odds ratio 6.00, P=0.043). In contrast, patients aged 40 years or over did not show significant association between disc degeneration and collagen IX genotype. Our results suggest that the Trp2 allele is an age-dependent risk factor for the severity of disc degeneration in younger patients with symptomatic herniated nucleus pulposus of the lumbar spine.

Adult↗
PubMed2005

Significance of lymph node micrometastasis in pN0 hilar bile duct carcinoma.

AIMS: To examine micrometastasis in node-negative hilar bile duct carcinoma (HBDC) using an immunohistochemical method and evaluated the clinical significance. METHODS: Four hundred and twenty three regional lymph nodes from 28 patients with node-negative HBDC who had undergone a resection were immunostained with an antibody against cytokeratins eight and 18 (CAM 5.2). RESULTS: Lymph node micrometastasis was detected in 11 of the 28 patients and 14 of the 423 lymph nodes. Lymph node micrometastasis was significantly correlated with the pT classification (p=0.03), the histopathological grading (p=0.01) and venous invasion (p=0.05). The 5-year survival rate of the patients with lymph node micrometastasis was 21.8%, as opposed to 66.5% in the patients without micrometastasis. Patients with micrometastasis showed a significantly poorer survival rate than those without micrometastasis (p=0.02). CONCLUSION: The results suggest that immunohistochemically detected lymph node micrometastasis has an impact on the outcome in HBDC.

Adult↗
PubMed2004

Presence of staphylococcal exfoliative toxin A in sera of patients with atopic dermatitis.

BACKGROUND: It has been reported that the toxins that Staphylococcus aureus produces are associated with the exacerbation of atopic dermatitis (AD). It has been shown in many studies that staphylococcal enterotoxin (SE) A and SEB contribute to AD by humoral immunity through IgE production as a superantigen. On the other hand, little attention has been paid to the relationship between AD and exfoliative toxin x (ETx). OBJECTIVE: We investigated the toxins that are frequently detected from the skin of patients and how these toxins affect AD. METHODS: S. aureus, isolated from the skin of 100 patients with mild to severe AD, were examined for the producibility of toxins by polymerase chain reaction. Serum samples were obtained from 21 patients with mild and moderate AD. The levels of SEB, ETA, total IgE, specific IgE, and specific IgG in sera were measured by ELISA. RESULTS: SEB was most frequently detected from S. aureus on the skin of these patients as previously reported. And ETx, to which little attention has been paid so far, was frequently detected next to SEB. Furthermore, ETA was detected from the sera of almost all the AD patients. SEB was not detected at all. Although the level of ETA in the AD group was significantly higher than that of controls, ETA-specific IgE was not detected from their sera. High levels of ETA tended to be detected from infantile patients. Although there were no significant differences in the levels of ETA-IgG between AD and the controls, its prevalence was more than twice as high as the controls in AD. CONCLUSION: These results suggest that many AD patients were exposed to ETx. We conclude that ETx may contribute to exacerbation of AD, particularly in infants, by a mechanism that is not through specific IgE production, unlike SEB.

Adolescent↗
PubMed2004

Resistance of differentiated human airway epithelium to infection by rhinovirus.

Virtually all in vitro studies of the effects of rhinovirus on human airway epithelium have used cells grown under conditions known to produce low levels of differentiation. The relevance of the results to native epithelium is questionable. Here we grew primary cultures of human tracheal or nasal epithelium under three conditions. One condition produced pseudostratified, mucociliary cells virtually indistinguishable from native epithelium. The other two conditions produced undifferentiated squamous cells lacking cilia. Cells were infected for 6 h with rhinovirus-16. After a 24-h incubation period, we determined levels of viral RNA in the cells, numbers of infectious viral particles released in the mucosal medium, expression of a variety of epithelial cytokines and other proteins, release of IL-6 and IL-8, and transepithelial electrical resistance and voltage. After infection, levels of viral RNA in the poorly differentiated cells were 30 or 130 times those in the differentiated. Furthermore, expression of mRNA for inflammatory cytokines, release of infectious particles, and release of IL-6 and IL-8 were closely correlated with the degree of viral infection. Thus well-differentiated cells are much more resistant to viral infection and its functional consequences than are poorly differentiated cells from the same source.

Cell Differentiation↗
PubMed2004

Prolactin gene expression in mouse spleen helper T cells.

Prolactin (PRL) is a single-chain polypeptide hormone that is generally secreted from prolactin cells of the anterior pituitary gland into the blood circulation. However, recent studies indicate that the gene expression of prolactin is ectopic in several tissues across several species. These studies found that lymphocytes also produce PRL, which is involved in the immunoregulatory system. Here, we searched for PRL messenger ribonucleic acid (mRNA), using the reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blotting in the spleens of mice at various growth stages. We also localized mouse prolactin (mPRL) and its mRNA in the spleens of 30- and 60-day-old mice by immunohistochemistry and in situ hybridization respectively. The mPRL gene was expressed in all spleen samples at 0-60 days postpartum. We localized mPRL mRNA in the sheathed artery, periarterial lymphatic sheath and the marginal zone of the spleen. Moreover, we detected mPRL in essentially the same area as its mRNA. Furthermore, we performed double-fluorescence immunohistochemical staining for mPRL and mouse CD4 that is specifically produced in helper T cells, or for mPRL and mouse CD19 or CD40 specified B cells. We colocalized mPRL immunoreactivity only in some CD4-immunopositive cells. These results clearly suggest that T cells synthesize mPRL in the mouse spleen.

Animals↗
PubMed2003

Clinical evaluation of a new enzyme immunoassay for hepatitis B virus core-related antigen; a marker distinct from viral DNA for monitoring lamivudine treatment.

We aimed to assess the clinical performance of a newly developed chemiluminescence enzyme immunoassay (CLEIA) for the detection of hepatitis B virus (HBV) core-related antigen (HBcrAg) in patients with chronic HBV infection. A total of 82 patients with chronic HBV infection and 167 HBV-negative controls were studied. HBcrAg was measured by CLEIA with monoclonal antibodies to hepatitis B e antigen (HBeAg) and hepatitis B core antigen (HBcAg), and HBV DNA was measured by transcription-mediated amplification assay (TMA) and in-house real-time detection polymerase chain reaction (RTD-PCR). The HBcrAg assay detected viremia in 189 of 216 samples (88%) collected from 72 patients whilst the TMA assay detected viremia in 178 of the 216 samples (82%) (P = 0.019). The HBcrAg concentration correlated linearly with the HBV DNA concentration (P < 0.001) over a range which varied 100 000-fold. The accuracy in the measurement of the patients' HBV load obtained using the HBcrAg assay was not affected by the absence of hepatitis B e antigen from the serum or the presence of precore mutations in the HBV genome. In patients without anti-viral drugs, changes in their serum HBcrAg concentration over time corresponded to their HBV DNA concentration. In six additional patients who were later treated with lamivudine, HBV DNA concentration declined more rapidly than their HBcrAg concentration. Three months after treatment commenced, the ratio of HBcrAg: HBV DNA had increased in all six patients (P = 0.031). The HBcrAg assay is a sensitive and useful test for the assessment of a patient's HBV load. When monitoring the anti-viral effect of lamivudine, HBcrAg provides a viral marker which is independent of HBV DNA.

Biomarkers↗
PubMed2001

Solvent effect on helicity induction of zinc bilinone bearing a chiral auxiliary at the helix terminal.

Solvent effects on helicity induction in zinc bilinone (ZnBL) derivatives bearing chiral auxiliaries at their 19-positions were investigated by using circular dichroic spectroscopy and (1)H NMR experiments. In ZnBLs 1 and 2, which possess (R)-2-methyl-1-phenylpropyloxy and (R)-1-phenylethyloxy groups at their 19-positions, respectively, the efficiency of helicity induction was significantly affected by employed solvents (78-95% de in 1 and 33-89% de in 2). The free energy changes of the P-M interconversion of 1 and 2 were linearly in proportion to reduction in polarizability of solvents: lower polarizability of solvents led to better efficiency of helicity induction in 1 and 2. With the support of the (1)H NMR study in addition to the molecular modeling previously reported, it was indicated that the solvophobic van der Waals interaction between the alkyl group in the chiral auxiliary and the A-ring of the bilinone skeleton in the preferred conformer plays a crucial role in determining the efficiency of helicity induction in 1 and 2.

Journal Article↗
PubMed2001

Apoptosis and the expression of Bcl-2 and Bax in patients with endometrioid, clear cell, and serous carcinomas of the uterine endometrium.

OBJECTIVES: Clear cell and serous carcinoma of the uterus are rare types of endometrial carcinomas. This study was designed to investigate the differential occurrence of apoptosis, Bcl-2, and Bax in endometrioid, clear cell, and serous carcinomas. METHODS: In a total of 28 endometrial carcinomas as well as 4 samples of normal postmenopausal endometria, apoptotic changes were examined using molecular biochemical techniques. The expression of Bcl-2 and Bax proteins was also investigated by immunohistochemical staining with appropriate antibodies. RESULTS: Labeling of DNA in situ indicated that apoptotic cells were sporadically seen in postmenopausal endometrium (5.2 +/- 2.1, n = 4). In contrast, cells undergoing apoptosis apparently were detected in endometrioid carcinoma (29.3 +/- 3.7, n = 20), and their numbers increased intensely in clear cell (49.5 +/- 5.6, n = 5) and serous carcinomas (50.8 +/- 6.0, n = 3). Autoradiographic analysis revealed that high-molecular-weight DNA was predominant in postmenopausal endometrium. However, a DNA ladder was identified in 7 of 10 carcinomas. Although Bcl-2 was immunonegative or faintly immunopositive in all cases, many cases of endometrioid carcinoma (43.6 +/- 4.1%, n = 20) were immunopositive for Bax, unlike postmenopausal endometrium (17.6 +/- 6.7%, n = 4). Moreover, the number of cells expressing Bax increased in clear cell (60.4 +/- 6.5%, n = 5) and serous carcinomas (66.8 +/- 7.6%, n = 3) compared with that in endometrioid carcinoma. CONCLUSIONS: These results indicate that apoptosis occurs in a specific population of cells in different histologic components of endometrial carcinomas. The expression of Bax, but not of Bcl-2, might suggest histologic differentiation in endometrial carcinomas.

Adenocarcinoma↗
PubMed2001

Endoscopic treatment of a long fibroepithelial ureteral polyp.

A case is reported of a 30-year-old woman with a long fibroepithelial polyp in the middle ureter treated with the Ho-YAG laser endoscopically. She presented with an intermittent macroscopic hematuria and lower abdominal pain lasting for 1 year. The filling defect on urography occupying one-third of the ureter was migratory depending on the patient position. Transurethral flexible ureterorenoscopy showed a large pedunculated tumor with a small base at the middle ureter. About 1 month after the endoscopic irradiation of the Ho-YAG laser to the base of tumor, the tumor was spontaneously discharged and pathologic examination revealed it to be a fibroepithelial polyp without malignant component. Postoperatively, the patient remained asymptomatic and follow-up excretory urographs showed no abnormal findings.

Adult↗
PubMed2001

Effects of left ventricular assist device on cardiac function: experimental study of relationship between pump flow and left ventricular diastolic function.

The left ventricular assist device (LVAD) with centrifugal pump has two characteristics. One is a pump flow wave of the centrifugal pump, consisting of the pulsatile flow of the native heart and the nonpulsatile flow of the centrifugal pump. The other is that the centrifugal pump fills from the native heart not only in the systolic phase, but also in the diastolic phase. In the case of the apex outlet LVAD with centrifugal pump, blood flows from the left atrium through the left ventricle to the pump. Pump flow is regulated by preload, and preload is regulated by diastolic hemodynamics. The aim of this study is to analyze the relationship between pump flow and the diastolic hemodynamics of the native heart. Ten anesthetized intact pigs were studied after placement of an LVAD. Data were recorded with the LVAD off (control) and the LVAD on. The assist rate was changed to 25%, 50%, and 75%. The indexes of left ventricular (LV) diastolic function included LV myocardial relaxation (time constant of isovolumic pressure decay [Tau] and maximum negative dP/dt [LV dP/dt min]) and LV filling (peak filling rate [PFR], time to peak filling rate [tPFR], and diastolic filling time [DFT]). Stroke volume decreased significantly in 75% assist. LV end-systolic pressure decreased significantly in 50% and 75% assist. LV end-diastolic volume decreased as assist rate increased, but there were no significant changes. Stroke work decreased significantly in 50% and 75% assist. LV dP/dt min decreased significantly in 50% and 75% assist. Tau prolonged as assist rate increased, but there were no significant changes. DFT shortened significantly in 75% assist. PFR increased significantly in 75% assist. tPFR shortened significantly in 50% and 75% assist. In this study, LV relaxation delayed as an increasing of pump assist rate, but it suggested a result of reduction of cardiac work. Also, it was suggested that LVAD increases the pressure difference between the left atrium and the left ventricle in the diastolic phase. This phenomenon is due to the filling of the left ventricle. In this study it was suggested that as pump assist rate increases, it is more effective to keep cardiac function in the diastolic phase.

Animals↗
PubMed2001

Apoptosis and the expression of Bax and Bcl-2 in hyperplasia and adenocarcinoma of the uterine endometrium.

BACKGROUND: Apoptosis plays a crucial role in carcinogenesis in various tumours. This study was designed to investigate the occurrence of apoptosis and the expression of Bcl-2 and Bax proteins in endometrial tumours of corpus uteri. METHODS: Endometrial tissues were obtained from 20 patients with endometrioid adenocarcinoma, 16 patients with endometrial hyperplasia, and 4 patients with myoma uteri (which were used as controls). The occurrence of apoptosis was examined by using molecular biochemical techniques. The expression of Bcl-2 and Bax proteins was also investigated using immunohistochemical staining with appropriate antibodies. RESULTS: The labelling of DNA in situ indicated that apoptotic cells were sporadically seen in postmenopausal endometrium (5.2 +/- 2.1, n = 4) and endometrial hyperplasia without atypia (2.6 +/- 0.5, n = 9). In contrast, labelled cells were detected in atypical endometrial hyperplasia (15.9 +/- 2.2, n = 7), and their numbers increased intensely in adenocarcinoma (29.3 +/- 3.7, n = 20). Autoradiographic analysis revealed DNA laddering in many cases of carcinoma. Bcl-2 was highly immunopositive in hyperplasia without atypia (36.2 +/- 6.5%, n = 9), but was decreased in the atypical endometrial hyperplasia (16.3 +/- 4.8%, n = 7). Large fractions of the carcinoma (6.3 +/- 1.8%, n = 20) and normal endometrium (2.8 +/- 1.4%, n = 4) were immunonegative or slightly immunopositive to Bcl-2. In contrast, Bax immunoreactivity was more frequent and stronger in adenocarcinoma (43.6 +/- 4.1%, n = 20) than that in normal endometrium (17.6 +/- 6.7%, n = 4) and hyperplasia (7.2 +/- 2.2%, n = 16). CONCLUSIONS: These results suggest that cells in hyperplasia expressing Bcl-2 might have prolonged survival ability. Neoplastic cells in adenocarcinoma might show apoptosis in association with a decreased expression of Bcl-2 and an increased expression of Bax. Therefore, the frequency of apoptosis and the expression of Bcl-2 and Bax might be correlated with carcinogenesis in the uterine endometrium of humans.

Adenocarcinoma↗
PubMed2001

Fetal circulatory responses to maternal blood loss.

We examined the fetal circulatory responses to maternal blood loss in pregnant women during the third trimester. Seven healthy women with placenta previa and singleton pregnancies underwent phlebotomies in an autologous donation program. Four hundred milliliters of blood was collected within 15 min at 34 and 35 weeks of gestation. Continuous electric recordings of fetal heart rate were performed during the first blood collection, and the maternal uterine artery (UtA), umbilical artery (UmA) and fetal middle cerebral artery (MCA) Doppler velocity waveforms were recorded before, immediately after and 24 h after the second collection in each patient. The average fetal heart rate, maternal UtA and UmA pulsatility indices did not change measurably during or after maternal blood collections. However, the average fetal MCA pulsatility index decreased significantly 24 h after maternal blood loss. The observation of a decrease in fetal MCA pulsatility index may indicate delayed fetal asphyxia following mild maternal hemorrhage.

Adult↗
PubMed2001

Evaluation of osmium(II) complexes as electron transfer mediators accessible for amperometric glucose sensors.

In order to lower the redox potentials of Os(III/II) complexes, the mixed ligand complexes of Os(II) were synthesized. The redox potentials of Os(III/II) complexes could be lowered by the use of 4,4'-dimethyl-2,2'-bipyridine (dmbpy), imidazole (Him) or its derivatives, and chloride ion as ligands, e.g., values of the redox (formal) potentials of 628 mV vs. Ag/AgCl for [Os(bpy)3]3+/2+ (bpy: 2,2'-bipyridine) and -6 mV for [OsCl(Him)(dmbpy)2]2+/+ were given in deaerated 0.1 mol dm-3 phosphate buffer (pH 7.0). The evaluation of Os(II) complexes as electron transfer mediators accessible for amperometric glucose sensors was examined according to the determination of the redox potentials of Os(III/II) complexes and the second-order rate constants for electron transfer between glucose oxidase (GOx) in reduced form and the Os(III) complex. Although the Os(II) complexes with lower redox potentials tended to decrease the second-order rate constants ks, the ks values for the majority of Os(II) complexes synthesized in this study were greater than that for ferrocenecarboxylic acid. Acceleration of the electron-transfer reaction is attributable to the hydrogen bonding and/or the electrostatic interaction between the Os(II) complexes and GOx. It may be consequently concluded that the mixed ligand complexes of Os(II) with bpy (dmbpy), Him (its derivatives), and Cl- can act as more efficient electron transfer mediators for the fabrication of amperometric glucose sensors.

Biosensing Techniques↗
PubMed2001

Performance of a conventional enzyme immunoassay for hepatitis C virus core antigen in the early phases of hepatitis C infection.

There are periods within the early phase of hepatitis C virus (HCV) infection in which the anti-HCV antibody test is unable to confirm HCV viremia. To reduce the risk of transmitting HCV through transfusions, we developed a simple and highly sensitive enzyme immunoassay (EIA) which detects the core antigen of HCV (HCVcAg). This assay employed a conventional colorimetric EIA system, and was based on a two-step sandwich assay, using a 96- well microplate. The reproducibility of the results was very high. When the cutoff values were set to 30 fmol of recombinant HCVcAg/L, as determined by the distribution of healthy subject sera (n=223), 99.6% of healthy subject sera and 100% of hepatitis B patient sera (n=50) were negative for HCVcAg. The clinical performance of this EIA was examined using 14 commercially available seroconversion panels. In every panel, HCVcAg could be detected at points preceding the seroconversion of anti-HCV antibodies. The points at which HCVcAg was detected were the same as those at which it was detected by an AMPLICOR HCV Monitor test. The EIA's window period for detecting the HCVcAg in all panels was on average 26 days shorter than that of the anti-HCV antibody test. In three panels where the first sample is negative for HCV RNA, the window period was shortened 50 days by this EIA for HCVcAg. There was a positive correlation between the concentration of HCVcAg and HCV RNA in anti-HCV antibody negative specimens. This assay was simpler to perform than assays based on gene amplification technology for the detection of HCV RNA, and the window period was shortened to that of the AMPLICOR HCV Monitor test. Thus, the EIA for HCVcAg would be useful in screening seroconverting donors and could reduce the residual risk of secondary HCV infections through transfusions.

Case-Control Studies↗
PubMed2001

Doppler echocardiographic evaluation of St. Jude Medical valves in the tricuspid position: criteria for normal and abnormal valve function.

BACKGROUND: Although this examination for mitral and aortic prosthetic valves has been frequently reported to be available for the early diagnosis of complications, there are few reports on examinations for tricuspid prosthetic valves, particularly the mechanical valve such as the St. Jude Medical (SJM) valve. Furthermore, the criteria for early diagnosis of complications are unknown. The purpose of this study is to evaluate the SJM valve in the tricuspid position by Doppler echocardiography and to analyze valve-related complications. METHODS: Between September 1978 and March 1997, 46 patients underwent tricuspid valve replacements with SJM valves; these cases were evaluated by Doppler echocardiography. We divided the cases into Normal and Complication groups. RESULTS: In the Normal group, peak pressure gradient was 4.2+/-1.5 mmHg and pressure half-time was 123.5+/-22.9 msec. In the Complication group, peak pressure gradient was 12.7+/-3.6 mmHg and pressure half-time was 271.8+/-76.4 msec. In the Complication group, the lowest peak pressure gradient case was 8.0 mmHg and the shortest pressure half-time was 160.0 msec. CONCLUSIONS: We concluded that when the peak pressure gradient is more than 8 mmHg or the pressure half-time is more than 160 msec, there is a possibility of complications. Despite the problems, the absence of any structural change after more than ten years suggests that the SJM valve can be used in the tricuspid position with careful follow-up.

Adult↗