Biomedical subjects

T Yagi

Publications and source records attributed to T Yagi.

At least 199 records · Page 11Linked to original sources

PubMed1999

[Three-dimensional analysis of eye movements induced by off-vertical axis rotation].

Off-vertical axis rotation (OVAR) is a method to stimulate the otolith organ. In order to elucidate the function of the otolith organ, we analyzed three-dimensional eye movements by video-oculographic technique during OVAR in 30 normal subjects. The eye movements induced by OVAR stimulation have two components: a constant horizontal deviation in the direction opposite to the rotation known as the bias component, and sinusoidal amplitude changes of eye movements known as the modulation component. Modulation components were detected in the horizontal, vertical, and torsional eye movements, but the bias components were only detected in the horizontal eye movements. The modulation components may compensate for changes in head orientation with respect to gravity. Since the bias component is caused by the velocity storage mechanism, the lack of bias components in vertical and torsional eye movements may suggest its specific relation to only horizontal eye movements. Our results also demonstrated that torsional and horizontal eye movements may originate from the utricle, whereas vertical eye movement may originate from the saccule. However, a lag phase between torsional and horizontal eye movements suggests that the most effective direction for stimulation of these two eye movements may be different.

Adult↗

PubMed1999

[Evaluation of mitral valve lesions in patients with infective endocarditis by three-dimensional echocardiography].

Recognition of the involved lesions is extremely important in mitral valve repair for infective endocarditis. Transesophageal echocardiography (TEE) is more sensitive for the detection of lesions than transthoracic echocardiography, but localization of the lesions is sometimes difficult by TEE. Three-dimensional (3D) TEE provides images of the mitral valve similar to the view from the left atrium. This study evaluated the value of 3D echocardiography for the diagnosis of involved lesions in 12 patients who underwent surgery for mitral regurgitation due to infective endocarditis. The location of the lesion in the mitral valve was classified as the medial, central and lateral portions of the anterior leaflet, and the medial, middle and lateral scallops of the posterior leaflet, respectively. In all patients, the involved sites were confirmed at operation. The sensitivities of 3D TEE for detecting the lesions at the medial, central and lateral portions of the anterior leaflet, and the medial, middle and lateral scallops of the posterior leaflet were 100%, 78% and 67%, and 100%, 100% and 100%, respectively. The specificities were 90%, 100% and 78%, and 100%, 100% and 100%, respectively. The lesions diagnosed by 3D TEE coincided with lesions confirmed at operation in 23 (92%) of 25 lesions. 3D TEE is useful for the assessment of the involved lesion of the mitral valve in patients with infective endocarditis.

Echocardiography, Three-Dimensional↗

PubMed1999

[New quinolone versus vancomycin/tobramycin for intestinal sterilization in patients who undergo allogeneic bone marrow transplantation].

The frequency of infection in recipients of allogeneic bone marrow transplants (BMT) who received oral new quinolones (NQ) was compared with that in BMT recipients who were given oral vancomycin/tobramycin (V/T). Between 1984 and 1997, our hospital treated 79 patients with V/T and 90 patients with NQ. Number of febrile days, duration of intravenous antibiotics administration, and frequency of documented infections were statistically the same for both groups. However, the frequency of grampositive bacterial infections, especially staphylococcal infections, was slightly higher in patients receiving NQ than in patients receiving V/T (p = 0.12). Of the patients who received NQ, those who underwent unrelated donor BMT procedures were generally febrile for slightly longer periods than those who underwent related donor BMT procedures (p = 0.10). These results suggest that oral NQ is as effective as oral V/T for the prevention of serious gramnegative bacterial infections in patients who undergo BMTs.

Administration, Oral↗

PubMed1999

[Usefulness of tissue harmonic imaging for the detection of left ventricular endocardial border].

Assessment of segmental wall motion is one of the most challenging tasks in echocardiography. One major limitation is impairment of echocardiographic regional wall motion by incomplete endocardial definition. The newly developed tissue harmonic imaging method may improve the detection of left ventricular endocardial border. This study examined the impact of native tissue harmonic imaging on endocardial border definition. Fundamental and harmonic imaging were compared for detecting the endocardial border in 96 segments of 16 patients (age 54 +/- 8 years). Visualization of endocardial border was better with harmonic imaging than with fundamental mode in 49% (47 of 96 segments). Thus, tissue harmonic imaging has a significant impact on endocardial border definition.

Cardiomyopathies↗

PubMed1999

Synergistic effects of anthraquinones on the purgative activity of rhein anthrone in mice.

This study was performed to determine whether intracaecally administered rhein anthrone and anthraquinones such as aloe-emodin, chrysophanol, emodin or rhein synergistically enhance the purgative action as has been observed for rhein anthrone and aloe-emodin anthrone. These anthraquinones were less potent than rhein anthrone. An equimolar mixture of aloe-emodin and rhein anthrone had synergistic potentiating effects because the ED50 value (50% purgative dose) of the combination was smaller than that calculated additively from the ED50 values of aloe-emodin and rhein anthrone. An equimolar mixture of other anthraquinones and rhein anthrone tended to potentiate the purgative action. These results confirmed that rhein anthrone and aloe-emodin synergistically exert a purgative action as has been observed for rhein anthrone and aloe-emodin anthrone.

Animals↗

PubMed1999

[Effects of imaging parameters on automated cardiac flow measurement using color Doppler echocardiography].

The color Doppler echocardiographic technique has been developed for automated cardiac flow measurement (ACM). This study evaluated the effect of imaging parameters on stroke volume measurement. Cardiac output derived from the ACM method was compared with that obtained from pulsed wave Doppler in 36 patients (26 men and 10 women, mean age 54 +/- 8 years) in whom clear two-dimensional and color Doppler images of the left ventricular outflow tract were obtained. The effects of frame rate, color gain and moving target indicator (MTI) filter on cardiac output were evaluated in 13 patients (8 men and 5 women, mean age 49 +/- 6 years). Using ACM at a frame rate of 30 Hz, optimal color gain setting and high-frequency MTI filter (cutoff frequency: 915 Hz), there was an excellent correlation in cardiac output between the ACM and pulsed wave Doppler methods (stroke volume: r = 0.91, SEE = 0.32 l/min). Using ACM at a frame rate of 30, 22 and 15 Hz, the differences in stroke volume were 4.4%, 5.2% and 8.6%, respectively. When color gain was reduced, left ventricular stroke volume reduction was 12.1% (-2 dB), 18.9% (-4 dB). In contrast, there was no significant change in stroke volume measurement when color gain was increased. There was a significant decrease in stroke volume using the low-frequency MTI filter [cutoff frequency: 467 Hz (-35.6%)] and medium-frequency MTI filter [cutoff frequency: 703 Hz (-13.4%)]. Color Doppler imaging parameters are extremely important for automated assessment of cardiac output.

Automation↗

PubMed1999

[A case of pulmonary tuberculosis case with pancytopenia accompanied to bone marrow gelatinous transformation].

A 45-year-old man did not visit a doctor in spite of his complains, cough and sputum lasting, for six months, and he finally could not eat without beer, and as a result, he lost his body weight and currently 52 kg. He became unconsciousness, was carried to a hospital, and was referred to our hospital. His sputum examination for acid fast bacilli was smear positive, Gaffky 6, for M. tuberculosis. His chest roentogenogram revealed large cavitary lesions in bilateral lung fields. On blood examination, WBC was 1100/microL, RBC was 256 x 10(4)/microL, and PLT was 13.4 x 10(4)/microL. Total protein was 4.7 g/dl, albumin was 1.9 mg/dl, and total cholesterol was 65 mg/dl. We tried to aspirate bone marrow from his sternum, but it was impossible. Hence we did biopsy of his ilium. The pathology of his bone marrow revealed gelatinous transformation. It was thought that the marked delay in visiting a doctor caused general consumption and loss of apetite, thus led to gelatinous transformation and finally pancytopenia.

Anorexia↗

PubMed1999

[Implantation of the artificial retina].

In some degenerative retinal diseases, e.g., retinitis pigmentosa and age-related macular degeneration, the photoreceptors are destroyed to cause serious visual defects. Recent studies on blind human subjects revealed that a large number of ganglion cells remains intact and is capable of transmitting signals to the brain to evoke partial visual perception. This provided hope to compensate for the visual defects with retinal prostheses. The recent progress of microfabrication technique made it possible to implement the Vary Large Scale Integrated circuit, the artificial retina, which emulates a part of retinal function. The idea of implanting the artificial retina to the patients was proposed recently and experiments using animals have been put into practice. This article surveys the front line of the artificial retina implantation.

Animals↗

PubMed1999

[Tuberculosis microepidemic in a commuter bus].

A tuberculosis microepidemic in a commuter bus was reported. Index patient was a 22-year-old woman who was an employee of an electronic company. An abnormal shadow was found on her chest roentgenogram during an annual medical check-up in June, 1996. As her sputum smear was Gaffky 6, she was admitted to our hospital for medication. Extraordinary examinations including PPD skin test and chest X-ray were carried out on 49 employees of the company in October, 1996. As the result of these examinations, the distribution of maximum diameters of erythema in PPD skin test showed bimodal distribution, and tuberculosis was discovered in two patients by Chest X-ray examination. Moreover, preventive administration of Isonicotinic acid hydrazide (INH) was indicated for 3 employees based on very strong skin reaction to PPD. These five employees were working separately from the index patient and had little contact with the patient in the work places, but using a same commuter bus. Therefore, we strongly suspect that they were infected from the index patient not in the work place but in the commuter bus. The air-conditioning of the bus used a closed recirculation system, hence insufficient ventilation in the bus contributed to the spread of tuberculosis infection.

Adult↗

PubMed1999

[Outbreak of multidrug-resistant Mycobacterium tuberculosis infection in the middle and advanced age].

We experienced a small outbreak of multidrug-resistant Mycobacterium tuberculosis infection (MDR-TB) among persons of in the middle and advanced age. The index case was 48-year-old man, and had complained productive cough since January 1996. He visited a doctor due to his symptom, and chest X-ray revealed cavitary lesion and sputum smear was positive for tubercle bacilli. He could not continue his admission because of his absence without leave and drinking, he was discharged on Day 54. The drug resistance was observed for INH (0.1 microgram/ml), RFP, and SM. Later, case 2, 52-year-old male, and case 3, 43-year-old-male, who were companions in mah-jongg with the index case, were diagnosed as pulmonary tuberculosis. The analysis of restriction fragment length polymorphism (RFLP) was done on 3 strains, and all showed the same pattern. Among other companions in mah-jongg with the index case, case 4, 28-year-old male, was treated as MDR-TB, and the drug resistance pattern was the same to that of the index case, but the details were unknown. Case 5, 65-year-old male, was diagnosed as drug sensitive pulmonary tuberculosis, thus he might incidentally suffer from pulmonary tuberculosis at the same time. Case 6, 46-year-old male, who had been treated for alcoholic liver cirrhosis, was introduced to our hospital as his sputum smear was positive, and the drug resistance pattern was observed similar to that of the index case. All the companions in mah-jongg suffered from MDR-TB except case 5. The RFLP analysis showed that the index case, case 2, and case 3 were caused by the same strain of M. tuberculosis. The drug resistance pattern of, case 4 and case 6 was the same to that of the index case. Based on these findings, it is highly suspected that this small outbreak was originated from the index case.

Adult↗

PubMed1999

[Measurement of left ventricular filling by automated contour tracking method in echocardiography: comparison with radionuclide ventriculography].

Recent development of an automated contour tracking (ACT) method using the energy minimization principle provides automated edge detection and tracking of the endocardial boundary of the left ventricle, without tracing a region of interest. This study determined whether left ventricular filling indexes obtained from the ACT method provide a reliable estimate of left ventricular diastolic filling. Fourteen patients were examined by the ACT method and equilibrium radionuclide ventriculography. The volume-time wave form for ACT measurements was obtained from the 4-chamber views. Peak filling rate and time to peak filling rate measured by the ACT method were compared with those determined by radionuclide ventriculography. Peak filling rate and time to peak filling rate by the ACT method were closely correlated with those determined by radionuclide ventriculography (peak filling rate: r = 0.88, y = 0.71x + 0.36, SEE = 0.54 ml/end-diastolic volume/sec, time to peak filling rate: r = 0.89, y = 0.72x + 30.0, SEE = 0.02 msec, respectively) The ACT method is useful for the assessment of left ventricular diastolic filling.

Aged↗

PubMed1999

[A case of pulmonary tuberculosis with acute renal failure caused by readministration of rifampicin].

We report a case of pulmonary tuberculosis with acute renal failure caused by readministration of Rifampicin (RFP). A 73 year-old man was admitted to a certain hospital complaining with dyspnea on exertion. As his sputum smear was positive for acid-fast bacilli, he was transferred to our hospital for the isolation and treatment. He was diagnosed as lung tuberculosis and was administrated RFP, Isoniazid (INH) and Ethambutol (EB). On the 20th day after the initiation of treatment, the administration of drugs were suspended, because of liver dysfunction. After recovery of liver dysfunction, we have readministered antituberculous drugs, starting with EB, then INH, and finally RFP. On the 22nd day after the readministration of RFP, acute renal failure was observed. All medications were suspended and we started treatment with hydration and furosemide. His renal function recovered after 7 weeks. Histopathological examination of the kidney revealed interstitial infiltration and tubular nephritis. According to the histopathological examination and the clinical course, we concluded acute renal failure was induced by the readministration of RFP. This case suggests that we have to pay attention to renal side effect of RFP in the course of readministration.

Acute Kidney Injury↗

PubMed1999

[An outbreak of Mycobacterium tuberculosis infection among young adults in close contact].

We experienced an outbreak of tuberculosis among young adults in close contact. The index case (case 1) was 22-year-old builder and was symptomatic for 9 months before diagnosis as pulmonary tuberculosis (PTB). His sputum smear was positive for tubercle bacilli. On immediate family contacts examination carried out at our hospital, his brother and sister (case 3, case 4) were detected as having PTB. His mother (case 5) and father (case 6) were later detected as having PTB by their symptomatic visits after some months, as tuberculin test as not done at first examination. Case 7 was 19-year-old-man, and was undiagnosed for 5 months. His sputum smear was positive. Immediately, contacts examination for case 7 as carried out at our hospital, and his colleague (case 8) was detected as having PTB. By interview with the case 7, it was found that the case 1 and the case 7 were close friends and spent long time together. Case 10 was 30-year-old builder, and he was accidentally referred to our hospital and was diagnosed as PTB. By the interview with the case 10, it was found that the case 1 and case 10 were members of builders group. This fact was informed to the F health center, and contacts examination for other members of the group were carried out by the F health center, and two young men were detected as having PTB. Analysis of restriction fragment length polymorphism (RFLP) showed that the case 1, the case 5, the case 7, and the case 10 were caused by the same strain of M. tuberculosis. Based on these findings, it is highly suspected that this outbreak was origined from the case 1, and 13 developed tuberculosis and 13 were primarily infected among contacts. The characteristics of this outbreak was that the family and contacts examination were enforced and most of the cases were detected at our hospital. If the outbreak of tuberculosis highly suspected, physicians should actively cooperate with health centers for contacts examination.

Adolescent↗

PubMed1999

Fas-mediated cytotoxicity by gammadelta T cells during acute rejection in xenotransplantation of spheroidal aggregate-cultured hepatocytes.

Xenogeneic transplantation has recently become a subject of interest for the transplantation community due to the current organ shortage, which could be partially or even totally solved by the development of this strategy. However, xenogenetic rejection remains a formidable barrier preventing such use in a clinical setting. The spheroidal aggregate-cultured hepatocytes of WKA rats were injected into the spleen of C3H mice, and quantitative assessment of transplanted xenogeneic hepatocytes using 99mTc-GSA demonstrated that hepatocytes decreased dramatically 2 days after transplantation (day 2) and few viable hepatocytes in spheroids were detected on day 3. The NK activity significantly increased on day 1, and gammadelta receptor/FasL-expressing T cells appeared on day 2. These results suggested that xenogeneic cytotoxicity consisted of gammadelta T cells through the Fas/Fas ligand system, as well as non-T-cell-mediated cellular response, in the MHC-unrestricted pathway in this intrasplenically transplanted xenogeneic hepatocyte model.

Animals↗

PubMed1998

Molecular analysis of mutations induced by acrolein in human fibroblast cells using supF shuttle vector plasmids.

Types of mutations induced by acrolein in the supF gene on the shuttle vector plasmid pMY189 replicated in normal human fibroblast cells were examined. Base sequence analysis of 92 plasmids with mutations in the supF gene revealed that the majority of the mutations were base substitutions (76%) and the others were deletions and insertions (24%). Single base substitutions were most frequently found (46%), while multiple base substitutions were 18% and tandem (two adjacent) base substitutions were 12% of the mutations. Of the base substitution mutations, G:C to T:A transversions were 44% and G:C to A:T transitions were 24%. The mutations were distributed not randomly but located at several hotspots. Acrolein produced DNA intra-strand cross-links between guanine residues, which might be responsible for rather high induction of the tandem base substitution mutations.

Acrolein↗

PubMed1998

Molecular remedy of complex I defects: rotenone-insensitive internal NADH-quinone oxidoreductase of Saccharomyces cerevisiae mitochondria restores the NADH oxidase activity of complex I-deficient mammalian cells.

The NDI1 gene encoding rotenone-insensitive internal NADH-quinone oxidoreductase of Saccharomyces cerevisiae mitochondria was cotransfected into the complex I-deficient Chinese hamster CCL16-B2 cells. Stable NDI1-transfected cells were obtained by screening with antibiotic G418. The NDI1 gene was shown to be expressed in the transfected cells. The expressed Ndi1 enzyme was recognized to be localized to mitochondria by immunoblotting and confocal immunofluorescence microscopic analyses. Using digitonin-permeabilized cells, it was shown that the transfected cells, but not nontransfected control cells, exhibited the electron transfer activities with glutamate/malate as the respiratory substrate. The activities were inhibited by flavone, antimycin A, and KCN but not by rotenone. Added NADH did not serve as the substrate, suggesting that the expressed Ndi1 enzyme was located on the matrix side of the inner mitochondrial membranes. Furthermore, although nontransfected cells could not survive in a medium low in glucose (0.6 mM), which is a substrate of glycolysis, the NDI1-transfected cells were able to grow in the absence of added glucose. When glycolysis is slow, either at low glucose concentrations or in the presence of galactose, respiration is required for cells to survive. The mutant cells do not survive at low glucose or in galactose, but they can be rescued by Ndi1. These results indicated that the S. cerevisiae Ndi1 was expressed functionally in CCL16-B2 cells and catalyzed electron transfer from NADH in the matrix to ubiquinone-10 in the inner mitochondrial membranes. It is concluded that the NDI1 gene provides a potentially useful tool for gene therapy of mitochondrial diseases caused by complex I deficiency.

Animals↗

PubMed1998

Fas/FasL interaction is not involved in apoptosis of activated CD4+ T cells upon HIV-1 infection in vitro.

In HIV-1-infected individuals, Fas expression and Fas/FasL-mediated apoptosis of mature T cells are known to increase compared with those in normal individuals. To elucidate a relation between acute HIV-1 infection and the regulation of Fas/FasL system upon T-cell activation, resting CD4+ T cells were acutely infected or uninfected with HIV-1 and subsequently activated by phorbol myristate acetate and ionomycin (PMA/IM). Four days after infection, when HIV-1 env gp120 is expressed in more than one half of activated T cells, Fas/FasL expression was analyzed by flow cytometry, and apoptosis-inducing activity of these activated primary CD4+ T cells on Fas+ Jurkat cells was examined. The level of Fas or FasL expression was not altered during acute HIV-1 infection. The enhanced apoptosis-inducing activity upon HIV-1 infection was observed in some individuals, but its activity was not Fas/FasL-mediated. These results indicate that HIV-1 infection is not necessarily associated with either upregulation of Fas/FasL expression or Fas/FasL-mediated apoptosis.

Antibodies, Monoclonal↗

PubMed1998

Structure-function studies of iron-sulfur clusters and semiquinones in the NADH-Q oxidoreductase segment of the respiratory chain.

Our recent experimental data on iron-sulfur clusters and semiquinones in the complex I segment of the respiratory chain is presented, focusing on the Paracoccus (P.) denitrificans and bovine heart studies. The iron-sulfur cluster N2 has attracted the attention of investigators in the research field of complex I, since the mid-point redox potential of this cluster is the highest among all clusters in complex I, and is pH dependent (60 mV/pH). It is known that this cluster is located either in the NQO6 (NuoB in E. coli/PSST in bovine heart nomenclature) or in the NQO9 (NuoI/TYKY) subunit in the amphipathic domain of complex I. Our preliminary data indicate that the cluster N2 is located in the NuoB rather than the long-advocated NuoI subunit, and may have a unique ligand structure. We previously reported spin-spin interactions between cluster N2 and two distinct species of semiquinone (designated SQNf and SQNs) associated with complex I. A parallel intensity change was observed between the SQNf (g = 2.00) signal and the N2 split g parallel signal, further supporting our proposed interaction between SQNf and N2 spins.

Animals↗