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Biomedical subjects

Y Tanabe

Publications and source records attributed to Y Tanabe.

At least 109 records · Page 6Linked to original sources
PubMed1998

[Clinical evaluation of Dumon stent for tracheobronchial stenosis due to advanced esophageal carcinoma].

We inserted Dumon stent to 13 patients with tracheobronchial stenosis due to advanced or recurrent esophageal carcinoma. Severe dyspnea was improved in 11 patients except for 2 patients with bilateral recurrent nerve palsy. 3 cases who had radiation therapy or chemotherapy lived over 150 days. We inserted esophageal stent in 4 cases. 2 patients died due to hemoptysis after 156 days and 35 days. We conclude that Dumon stent is one of the useful treatments in order to improve quality of life and prognosis of advanced or recurrent esophageal carcinoma.

Aged↗
PubMed1998

Cerebral blood flow measurement in patients with impaired consciousness: usefulness of 99mTc-HMPAO single-photon emission tomography in clinical practice.

The relationship between impairment of consciousness and quantitative cerebral blood flow (CBF) was investigated. The mean CBF of the whole brain was measured by the Patlak-plot method using technetium-99m hexamethylpropylene amine oxime single-photon emission tomography (99mTc-HMPAO SPET) in patients with the following diseases: cerebral infarction, intraparenchymal haemorrhage, subarachnoid haemorrhage, brain tumour and cerebral contusion. The clinical symptoms were evaluated according to the severity of impaired consciousness, aphasia and dementia. Four hundred and eighty-five CBF measurements were performed. Patients with alert consciousness showed an age-related decline in mean CBF. Patients with aphasia showed a significant reduction in mean CBF compared with those without aphasia. Impaired consciousness was proportional to reduction in mean CBF regardless of types of pathology, and the size of lesion did not influence the mean CBF. Patients with dementia showed a significant reduction in mean CBF proportional to the severity of dementia. The quantitative measurement of CBF using 99mTc-HMPAO SPET is reliable in clinical evaluations.

Adolescent↗
PubMed1998

Liposome drug delivery system for murine neuroblastoma.

PURPOSE: The effects of liposome-infused doxorubicin on C-1300 murine neuroblastoma were studied. The liposome surface was covered with polyethylene glycol to avoid migration toward the reticuloendothelial system and to prolong its presence in the bloodstream. Liposome-infused doxorubicin hydrochloride (DXR), an anthracycline was used as an anticancer antibiotic substance. METHODS: Each A/J mouse was transplanted with 1 x 10(5) C-1300 murine neuroblastoma cells subcutaneously in the thigh. The experiment was conducted when the maximum tumor dimension was 1 cm. The control group was given only physiological saline solutions, the second group was given DXR alone, and the third group received liposome-infused DXR (Lip-DXR). The survival and doubling times were measured. One, 12, and 24 hours after the injection, the DXR concentration in the cardiac tissues was measured for statistical comparison. RESULTS: The survival time of the mice was found to be 27+/-5.10 days in the control group, 31.40+/-3.15 days in the DXR group, and 43.86+/-2.13 days in the Lip-DXR group. The Lip-DXR group showed the longest survival time. The tumor-doubling time was found to be 9.07+/-2.30, 10.75+/-3.49, and 19.80+/-3.26 days, for each group, respectively. When comparing the DXR concentration in the heart tissues, the Lip-DXR-administered mice showed significantly lower DXR accumulation in the cardiac tissues after 1 and 12 hours than the DXR-administered mice. CONCLUSION: This study proved that liposome-infused DXR could be used effectively on murine neuroblastoma (C-1300 tumor cell model) and may reduce the incidence of cardiac toxicity as compared with DXR alone.

Animals↗
PubMed1998

Long-term supplementation with a high cholesterol diet decreases the release of ATP from the caudal artery in aged rats.

We examined the effects of high cholesterol (HC) diet on the spontaneous and noradrenaline-induced release of ATP, ADP, AMP and adenosine from caudal arteries and on the plasma levels of these adenyl purines in aged (100-week-old) Wistar rats. Administration of this diet for 12 weeks significantly reduced spontaneous and noradrenaline (1 micromol/L)-evoked release of adenyl purines from the caudal arteries relative to rats given the control diet The unsaturation index of fatty acids (UI), which gives the average number of double bonds, of both the plasma and the caudal artery was significantly less in the HC diet-fed rats than in those fed the control diet. The HC diet for 12 weeks produced a slight but significant increase in systolic and diastolic blood pressure with advancing age. Regression analysis revealed a significant inverse relationship between the total amount of purines released from the artery and diastolic blood pressure, and also a positive relationship between the total amount of purines released and the UI of the caudal artery. These results suggest that the high cholesterol diet decreased the release of adenyl purines from the caudal arteries of aged rats, leading to an increase in blood pressure.

Adenosine↗
PubMed1998

Adolescent case of Alexander disease: MR imaging and MR spectroscopy.

A 17-year-old male was diagnosed as having Alexander disease from the clinical manifestations (psychomotor deterioration and megalencephaly), neuroradiologic findings (frontal dominant leukodystrophy), and elevation of alpha B-crystallin and heat shock protein 27 in the cerebrospinal fluid. He exhibited increased attenuation on computed tomography and T1 and T2 shortening on magnetic resonance imaging in the bilateral basal ganglia and thalamus. Some paramagnetic substances might be deposited in the basal ganglia and thalamus in the late stage of Alexander disease, at least 8 years after onset.

Adolescent↗
PubMed1998

Administration of killed bacteria together with listeriolysin O induces protective immunity against Listeria monocytogenes in mice.

It is known that only listeriolysin O (LLO)-producing Listeria monocytogenes strains are able to induce protective immunity, but the underlining relationship between LLO produced by virulent strains and generation of protective immunity in the infected host remains poorly understood. In the present study, it was found that LLO gene expression was only detected in the mice infected with virulent strain which was able to induce protective immunity, while non-virulent strains or killed bacteria were not able to generate protective immunity. When mice were immunized with LLO plus killed bacteria in the presence of incomplete Freund's adjuvant, the protective immunity was partially generated, and adoptive transfer experiment confirmed that this protection was antigen specific. Reverse-transcription polymerase chain reaction revealed that LLO plus killed bacteria induced the expression of interferon-gamma (IFN-gamma) and interleukin-12 (IL-12). Our results also showed CD4+ T cells were the principal cells constituting protective immunity. Taken together, it may be concluded that LLO produced from virulent strains of L. monocytogenes was essential for the generation of protective immunity, and that LLO plus killed bacteria induced IFN-gamma and IL-12 expression which resulted in the generation of protective immunity.

Adoptive Transfer↗
PubMed1998

Killing mechanism of Listeria monocytogenes in activated macrophages as determined by an improved assay system.

Exposure of Listeria monocytogenes to gentamicin 5 mg/L for 4 h resulted in the killing of most extracellular bacteria, but had no effect on the survival of bacteria inside macrophages. Higher concentrations of gentamicin caused a reduction in the number of intracellular bacteria. This effect was associated with cellular uptake of gentamicin, but was unaffected by activation of macrophages by interferon-gamma and lipopolysaccharide. In experiments in which exposure to gentamicin 5 mg/L for 4 h was used to kill extracellular bacteria, killing by activated macrophages was impaired when O2- production was inhibited by superoxide dismutase, but not when nitric oxide production was blocked by NG-monomethyl-L-arginine. These data suggest that the reactive oxygen intermediates are more important than nitric oxide in the killing of L. monocytogenes, at least in macrophages activated in vitro.

Animals↗
PubMed1998

Comparison of arrhythmogenicity of atrial pacing at several right atrial pacing sites: evaluation of canine atrial electrograms during atrial pacing and arrhythmogenicity for atrial fibrillation.

The changes in the duration of atrial electrograms and the appearance of AF during atrial pacing were compared among five atrial pacing sites in dogs to clarify the arrhythmogenicity of atrial pacing at different atrial pacing sites. In seven mongrel dogs (15-20 kg), the right atrial surface was exposed by right thoracotomy. Atrial electrograms were recorded via bipolar electrodes with an interelectrode distance of 1.2 mm at four right atrial sites: (1) the high right atrium (HRA), (2) the mid-right atrium (MRA), (3) the low right atrium (LRA), and (4) the center of the pectinate muscle (PM). The duration of the atrial electrograms at these four recording sites were measured during atrial pacing with fixed cycle lengths of 200, 150, and 120 ms delivered at five atrial sites: (1) the HRA, (2) the inferior vena cava (IVC), (3) the right atrial appendage (RAA), (4) Bachman's bundle (BB), and (5) the atrial septum (AS). In each dog, the atrial pacing with the 120-ms cycle length was performed five times at each pacing site to evaluate the inducibility of AF. When AF was induced, the atrial recording site which first showed a fragmented atrial electrogram was considered the initiation site of the AF. AF was induced during 9 of 35 episodes of atrial pacing at the HRA site, 11 of 35 at the IVC site, 5 of 35 at the RAA site, 3 of 35 at the BB site, and none at the AS site. The initiation site of AF was in the HRA site in 11 of 28 episodes of induced AF, in the MRA site in 9 of 28, and in the LRA site in 8 of 28. At each recording site, the shorter the paced cycle length, the longer the duration of the atrial electrogram regardless of the pacing site. During the atrial pacing with the 200-ms cycle length, the HRA pacing resulted in the shortest duration of the atrial electrogram at each recording site in comparison with the other pacing sites. However, during atrial pacing at the two shorter paced cycle lengths, the duration of the atrial electrogram was shorter during the pacing at the BB or AS sites in comparison with the other three pacing sites, i.e., the HRA, IVC, and RAA sites. These results were the same for all atrial recording sites, but the prolongation of the atrial electrogram was most prominent at the HRA and MRA recording sites, which are most likely initiation sites of the induced AF. In the canine atria, (1) the initiation sites of AF were likely to be the HRA, MRA, or LRA sites in comparison with the PM site; and (2) the atrial pacing at the BB or AS sites was considered less arrhythmogenic for AF than the pacing at the HRA, LRA, or RAA sites.

Animals↗
PubMed1998

Optimum tube voltage for chest radiographs obtained by psychophysical analysis.

Many kinds of x-ray films having various characteristic curves have been developed for chest radiographs. In general, a phototiming device for determination of a mAs value which gives a proper exposure has been used for a chest radiography. For each film, however, the x-ray tube voltage has been determined by the subjective evaluation of radiologists or radiological technologists. In this paper, we propose a new method for determining the optimum tube voltage for chest radiographs using psychophysical analysis. The optimum density and the optimum density range of a screen/film system are obtained from the gradient curve of film and the minimum perceptible contrast delta Dmin [Acta Radiol. Diagnos. 4, 463-476 (1966)]. The optimum tube voltage, by which the lowest density of a mediastinum and the highest density of a lung field just cover the optimum density range, is obtained using the x-ray photon spectrum and sensitivity spectrum of the screen. This objective method does not depend on personal subjective evaluation, therefore it is available for the determination of optimum tube voltage for chest radiographs to be observed by many doctors of various departments.

Humans↗
PubMed1998

The contributions of reactive oxygen intermediates and reactive nitrogen intermediates to listericidal mechanisms differ in macrophages activated pre- and postinfection.

The contribution of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI) to the killing of Listeria monocytogenes by macrophages activated by addition of spleen cells from listeria-immune mice plus specific antigen was examined. When macrophages were infected with L. monocytogenes and then spleen cells were added, there was not as big a difference in listericidal activity between macrophages cultured with normal spleen cells and those cultured with immune spleen cells as expected. In this culture system, RNI was mainly involved in the macrophage intracellular killing. In macrophages first activated and then infected, a significant level of enhanced killing was observed. Blockade of ROI production drastically affected the enhanced killing ability, while inhibition of RNI production had a negligible effect. Thus, the contributions of ROI and RNI to listericidal mechanisms of macrophages were different between macrophages activated at pre- and postinfection stages.

Animals↗
PubMed1998

A follow up study of myocardial involvement in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS).

OBJECTIVE: To investigate cardiac function in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) and clarify the clinical features of cardiomyopathy in MELAS. PATIENTS: 11 consecutive patients with MELAS (mean age at initial examination 11.3 years, range 4 to 16 years) were enrolled in the study. Six were followed for more than five years. RESULTS: On echocardiographic examination, three patients showed increased left ventricular end diastolic posterior wall thickness (LVPWTd), exceeding 140% of the normal value. Four patients, including these three, had an ejection fraction of less than 50%, and two also had increased left ventricular end diastolic volume (LVEDV) exceeding 140% of the normal value (%N). The LVPWTd%N was correlated positively with the LVEDV%N (R = 0.669, p < 0.05) and negatively with the ejection fraction (R = -0.6701, p < 0.05). One patient died of heart failure aged 22 years. CONCLUSIONS: The cardiomyopathy in MELAS is characterised by an abnormally thick left ventricular wall with progressive dilatation and poor left ventricular contraction developing over several years, indicating hypertrophic cardiomyopathy advancing to dilated cardiomyopathy.

Adolescent↗
PubMed1998

Reentrant ventricular tachycardia. Interpretations of electrophysiologic findings and its applications.

Monomorphic sustained ventricular tachycardia (MSVT) was revisited in relation to the electrophysiologic findings and their relation to the drug efficacy. Old myocardial infarction is less common cause of MSVT in Japan, and the majority (about 2/3) of MSVT is unrelated to coronary artery disease but, the mechanism shared a common mechanism: reentry with an excitable gap as others. The reentrant mechanism was supported from the inducibility, the terminability of VT by electrical stimulation, and by the ability to entrain with rapid pacing. In MSVT associated with underlying heart diseases, diseased myocardium showed low amplitude and fragmented electrograms and the area was considered to participate as the central common pathway of reentrant circuit. The area of slow pathway showed a decremental conduction or all-or-nothing conductive property. The width of the excitable gap seemed to be determined by the maximal conductive frequency but not by the duration of action potential: effective refractory period. As to the drug efficacy, there was no baseline characteristics in predicting the efficacy. However, the significant narrowing of the width of the excitable gap was associated with the drug efficacy and VT became non-inducible after addition of the same drug. The response pattern of the excitable gap to specific drug including class III, was not predictable. Further electropharmacological studies will be warranted.

Anti-Arrhythmia Agents↗
PubMed1998

[Formation of genetic polymorphism in connection with phylogenesis and microevolution of the domestic dog Canis familiaris L].

The analysis of genetic relationships between numerous breeds and populations of domestic dogs of Asian and European origin was performed by studying their polymorphism for 14 loci of biochemical markers. Phylogenetic positions of different breed groups, related to one another and to ancestral forms from the center of domestication, were elucidated. Directions of gene flow in the formation of breed as well as dynamics and vectors of the forming genetic structure in microevolution of this extremely polytypic species, were established.

Animals↗
PubMed1998

Progression to moderate or severe mitral regurgitation after percutaneous transvenous mitral commissurotomy using stepwise inflation technique.

Progression to moderate or severe mitral regurgitation (MR) was studied after Inoue balloon percutaneous transvenous mitral commissurotomy (PTMC) using the stepwise inflation technique, performed at increments of 1 mm of balloon diameter, in 49 consecutive patients with rheumatic mitral stenosis (aged from 32-73 years; 8 males, 41 females). The patients were classified on the basis of the degree of MR after PTMC, compared with that before PTMC, into either Group A, development of moderate or more severe (> or = grade 2) MR (n = 8) or Group B, no increase in MR or development of mild (grade 1) MR (n = 41). Progression to moderate or severe MR was significantly associated only with advanced age (60 +/- 8 vs 52 +/- 10 years, p < 0.05) and narrower mitral valve area (0.87 +/- 0.35 vs 1.11 +/- 0.29 cm2, p < 0.05), but other characteristics before PTMC were similar in both groups. There was no difference between the two groups in the total number and degree of balloon inflation. Immediately before the final inflation, the left atrial mean pressure and v wave pressure were decreased in smaller degrees in Group A compared with Group B (-2 +/- 2 vs -5 +/- 4 mmHg, p < 0.05; -2 +/- 2 vs -6 +/- 6 mmHg, p < 0.05, respectively). Thus, the stepwise inflations require careful monitoring of changes in the left atrial pressure and waveform to recognize the aggravation of MR, especially in older patients with severe stenosis. Patients who do not have a significant drop in left atrial mean pressure and v wave pressure during stepwise inflations of the balloon might be at risk of development of moderate or severe MR after further dilations.

Adult↗
PubMed1998

[Usefulness of CT-guided aspiration biopsy in combination with rapid cytology for diagnosis of benign pulmonary lesions].

PURPOSE: To evaluate the diagnostic accuracy of computed tomography (CT)-guided aspiration biopsy in combination with rapid cytology for benign pulmonary lesions. MATERIALS AND METHODS: We performed percutaneous aspiration biopsy under CT guidance in combination with a rapid cytologic examination in 91 patients with pulmonary lesions. A 21-gauge modified Menghini needle coaxially placed through an 18-gauge needle was used in this procedure. Thirty-one lesions that were confirmed as a benign pulmonary lesion histologically, serologically, bacteriologically and/or clinically were evaluated in this study. RESULTS: In 28(90.3%) of 31 lesions, sufficient material for cytologic diagnosis was obtained from the aspiration biopsy. Specific benign diagnosis for benign disease was obtained in 13 lesions (41.9%), while nonspecific diagnosis for benign disease was obtained in 15 lesions (48.4%). The overall accuracy of the rapid cytological examination was 90.3%. Pneumothorax developed in 17 patients (54.8%), with 7 patients (22.6%) requiring chest tube drainage. Only one patient complained of mild hemoptysis, which subsided with hemostatic agents. CONCLUSION: Percutaneous aspiration biopsy combined with a rapid cytologic diagnosis provides a high degree of accuracy in the diagnosis of benign pulmonary lesions.

Adult↗