Search PubMed⌕ Search

Biomedical subjects

T Maeda

Publications and source records attributed to T Maeda.

At least 361 records · Page 20Linked to original sources
PubMed1998

Effect of exercise-induced activation of sympathetic nerve activity on clearance of 123I-MIBG from the myocardium.

The effect of exercise on the cardiac kinetics of 123I-MIBG was investigated in the present study. 123I-MIBG was administered intravenously at rest in 6 healthy male volunteers, and anterior planar and SPECT images were obtained 15 minutes, and 2 and 4 hours after administration (protocol A). After 4 weeks, 123I-MIBG was again administered intravenously at rest, and images were obtained 15 minutes later. After imaging, the subjects ran 10 km in approximately 1 hour, and anterior planar and SPECT images were obtained 2 and 4 hours after administration of 123I-MIBG (protocol B). The heart-to-mediastinum uptake ratio (H/M) was calculated from each anterior planar image, and the mean 123I-MIBG clearance from 15 minutes to 2 hours, and from 2 hours to 4 hours was calculated with a bull's eye display. The H/M was much lower after exercise. The mean clearance rate between 15 minutes and 2 hours in protocol B was significantly higher than that between 2 hours and 4 hours, and that between 15 minutes and 2 hours in protocol A. It was concluded that the clearance rate of 123I-MIBG may be a useful index of cardiac sympathetic nerve activity.

3-Iodobenzylguanidine↗
PubMed1998

Early and delayed Tc-99m-tetrofosmin myocardial SPECT in patients with left bundle branch block.

UNLABELLED: To determine the utility of the myocardial tracer Tc-99m-tetrofosmin in the examination of patients with left bundle branch block (LBBB) and to investigate Tc-99m-tetrofosmin uptake and retention in the myocardium, early and delayed Tc-99m-tetrofosmin SPECT was performed in 10 patients having LBBB without coronary stenosis. METHODS: After 740 MBq of Tc-99m-tetrofosmin injection in the resting state, the early and delayed SPECT imaging was done at 30 min and 180 min, respectively. RESULTS: Decreased Tc-99m-tetrofosmin uptake in the septal segments was observed in 4 patients (40%) at 30 min and in 9 (90%) at 180 min. Reverse redistribution was seen in 9 of 10 patients. In patients with LBBB, the septal-to-lateral uptake ratio was lower in the delayed images than in the early images (0.80 +/- 0.09 vs. 0.89 +/- 0.09, p < 0.001). In patients with LBBB, the washout rate of Tc-99m-tetrofosmin was higher in the septal segments than in the lateral segments (28.3 +/- 4.3% vs. 22.8 +/- 3.3%, p < 0.001). CONCLUSION: The SPECT data indicate that in LBBB without coronary stenosis, the uptake of Tc-99m-tetrofosmin is decreased in the septal wall, and that reverse redistribution occurs frequently. Our results contribute to the elucidation of both the cellular biokinetics of Tc-99m-tetrofosmin in the myocardium and the hemodynamics of the septum in LBBB, and indicate the possible clinical utility of Tc-99m-tetrofosmin.

Adult↗
PubMed1998

Reverse redistribution of Tc-99m-tetrofosmin in exercise myocardial SPECT in patients with hypertrophic cardiomyopathy.

We examined the usefulness of Tc-99m-tetrofosmin in detecting exercise induced perfusion abnormalities in patients with hypertrophic cardiomyopathy (HCM) and to clarify time-related changes in myocardial distribution of Tc-99m-tetrofosmin after a single injection. We studied 44 consecutive patients with HCM by means of exercise/rest Tc-99m-tetrofosmin single photon emission computed tomography (SPECT). After injecting 370 MBq of Tc-99m-tetrofosmin at the peak exercise, the early SPECT imaging was performed at 30 min (EX-30) and the delayed imaging at 180 min (EX- 180). Immediately after the delayed imaging, 740 MBq of Tc-99m-tetrofosmin was injected in the resting state, and the rest SPECT imaging was performed 30 min later. Exercise-induced regional perfusion defects and/or apparent reversible left ventricular cavity dilation were identified in 26 (68.2%) of the 44 patients. When EX-30 images and EX-180 images were compared, reverse redistribution was confirmed in 36 patients (81.8%). Reverse redistribution was detected most frequently in the septal portion of the anterior wall, followed by the septal portion of the posterior wall and the septum. Exercise/rest Tc-99m-tetrofosmin myocardial imaging was a useful method for assessing myocardial perfusion abnormalities in patients with HCM. Reverse redistribution was detected very frequently on early and delayed images of exercise. We assumed that reverse redistribution may reflect a retention disorder of Tc-99m-tetrofosmin caused by some metabolic dysfunction of myocytes.

Cardiomyopathy, Hypertrophic↗
PubMed1998

Effects of diltiazem on myocardial perfusion abnormalities during exercise in patients with hypertrophic cardiomyopathy.

The effect of diltiazem on myocardial ischemia in patients with hypertrophic cardiomyopathy (HCM) was evaluated by exercise myocardial 201Tl single photon emission computed tomography (SPECT). Exercise myocardial SPECT was performed before and 8 weeks after oral administration of diltiazem (180 mg/day) in 20 patients with HCM who showed transient perfusion defects on exercise myocardial 201Tl SPECT under control conditions. SPECT images were divided into 17 segments. The 201Tl perfusion defects were visually scored and evaluated as the defect score. The transient dilation index was calculated as an index of subendocardial ischemia. Improvement of the defect score was demonstrated in 15 patients after the administration of diltiazem. The mean defect score decreased significantly from 9.90 +/- 5.17 to 5.50 +/- 4.89 (p < 0.0001). Although 16 of 20 patients showed an abnormal transient dilation index before diltiazem treatment, 16 showed improvement and 13 of these normalized after diltiazem therapy. The mean transient dilation index decreased from 1.16 +/- 0.10 to 1.02 +/- 0.09 (p < 0.0001). In conclusion, diltiazem prevents or diminishes myocardial ischemia in patients with HCM.

Adult↗
PubMed1998

[Postoperative therapy using human atrial natriuretic peptide in cases of valve replacement].

The effect of hANP (atrial natriuretic peptide) was investigated clinically in 40 patients who underwent isolated valve replacement. Patients were divided into four groups: aortic regurgitation (AR), aortic stenosis (AS), mitral regurgitation (MR) and mitral stenosis (MS). Each group was divided into two subgroups: one was administered hANP after the operation until leaving ICU, and the other was not administered hANP. We measured the levels of hANP and c-GMP and blood pressure, pulmonary artery pressure, central venous pressure and levels of Na, K of urine and blood prcoperatively, immediately postoperatively and 1, 2, 4, 6 hours after operation. First, to examine the relationship between preoperative level of hANP and cardiac function, the relationship between preoperative level of hANP and history of cardiac failure and pulmonary artery wedge pressure (PAWP) were evaluated. Also, we evaluated the relationship between preoperative level of hANP and each dimension on echocardiography. There was a weak statistical relationship between hANP and PAWP (row = 0.39 (p = 0.04) Pearson correlation method) and there was no statistical relationship between hANP and duration of cardiac failure (row = 0.00445 (p = 0.98) Pearson correlation method). Preoperatively Left atrial diameter (LAD) showed a statistical relationship with level of hANP in every group using Spearman correlation method. Other dimensions such as left ventricular diastolic diameter (LVDd) and left ventricular systolic diameter (LVDs) and also fractional shortening (FS) did not show a strong correlation with preoperative level of hANP. Especially, in AS group there was a strong relationship between every dimension and preoperative level of hANP. Only in MS group LAD and the level of hANP were negatively related. This finding suggests that atrial dilatation results in reduction of secretion of hANP in cases of MS on long term follow up. Finally, hNAP therapy was shown to have a continuous diuretic effect, with stable hemodynamics.

Adult↗
PubMed1998

Abnormal development of serotonin nerve fibers in the visual cortex in rats with methylazoxymethanol-induced microcephaly.

The postnatal development of serotonin (5HT)-immunoreactive axons was studied in the visual cortex of the cerebrum in both normal and microcephalic rats during early postnatal and young adult stages. Severe microcephaly in rat offspring was induced by prenatal exposure to methylazoxymethanol acetate (MAM), an anti-mitotic agent, on day 15 of gestation. From postnatal day 1 (PND 1) to PND 5, fine and short 5HT fibers were irregularly dispersed throughout the occipital cortex in both the control and MAM-treated rats (MAM-rats). A conspicuous aggregation of dot-like 5HT terminals was found in controls, but not in MAM-rats, in a shallow layer of the dorsomedial region of the occipital cortical plate. On PND 7, such an aggregation of 5HT terminals was found in both groups. The density of the aggregation increased up to PND 9, but then decreased gradually, finally becoming unrecognizable at around PND 15 in both groups. MAM-rats, however, always showed hyperaggregation of 5HT terminals when compared with controls on the same PND. The density of 5HT fibers gradually increased, and finally made up a network-like formation at PND 28 in both groups, its pattern was essentially identical to the abnormal distribution of 5HT fibers during the later stage. As a result, the network-like formation of 5HT fibers in the MAM-rats at PND 28 was markedly twisted and somewhat hyperdense. In Nissl-stained preparations from PND 9 to 15, the 5HT terminal aggregation in the control rats was precisely confined to the newly forming layer IV of the visual cortex. In the MAM-rats, on the other hand, the aggregation of 5HT terminals was not associated with a specific cortical layer because of a disarranged cytoarchitecture of the microcephaly.

Animals↗
PubMed1998

Calbindin D28k-like immunoreactivity in the developing and regenerating circumvallate papilla of the rat.

The distribution of calbindin D28k (CB)-like immunoreactivity (-LI) in the circumvallate papilla (CVP) was examined during development and regeneration following bilateral crush injury to the glossopharyngeal nerve in the rat. In the adult CVP, CB-like immunoreactive (-IR) nerve fibers were observed in the subgemmal region and some penetrated into the taste buds. CB-LI was also detected in the cytoplasm of the spindle-shaped gustatory cells in the lower half of the trench epithelium, which contained numerous synaptic vesicles and bundles of intermediate filaments. These CB-IR gustatory cells made synapse-like contacts with CB-IR nerve terminals. Some CB-IR nerve terminals made contacts with the gustatory cells negative for CB-LI. At least three developmental stages were defined with regard to the developmental changes in the distribution of CB-LI: (1) Stage I (embryonic day (E) 18-postnatal day (P)5): CB-IR nerve fibers appeared in the lamina propria just beneath the newly-formed CVP at E18, but the gustatory epithelium of the CVP contained no CB-IR structures. Taste buds with taste pores appeared at P1. (2) Stage II (P5-10): thin CB-IR nerve fibers began entering the trench epithelium, but no CB-IR cells were observed. (3) Stage III (P10-adult): in addition to the intragemmal and perigemmal CB-IR nerve fibers, very few CB-IR cells appeared in the taste buds around P10, and their numbers increased progressively. The changes in the distribution of taste buds and CB-LI following glossopharyngeal nerve injury were similar to those observed during development. On post-operative day (PO) 4, the taste buds and CB-IR cells decreased markedly in number. These CB-IR cells became round in shape, and the number of CB-IR nerve fibers decreased markedly. On PO8, both taste buds and CB-IR cells disappeared completely. The regenerated taste buds were first observed on PO12, increased rapidly in number by PO20, and increased slowly thereafter. CB-IR nerve fibers accumulated at the subgemmal region and began penetrating into the trench wall epithelium around PO16. CB-IR cells appeared between PO20 and PO24, and their numbers increased progressively and reached the normal level on PO40. The topographical localizations of the taste buds and CB-IR cells during development and regeneration were comparable to those of normal animals. The delay of the time courses for appearance of CB-IR nerve fibers and CB-IR cells compared to the appearance of taste buds during development and regeneration suggests that CB in the gustatory epithelium may participate in the survival of the taste bud cells rather than in the induction of the taste buds.

Age Factors↗
PubMed1998

Immunohistochemical observation of growth-associated protein 43 (GAP-43) in the developing circumvallate papilla of the rat.

The distribution and development of growth-associated protein 43 (GAP-43)-like immunoreactivity (-LI) in the rat circumvallate papilla (CVP) were compared to those of protein gene product 9.5 (PGP 9.5)-LI. In the adult, thick GAP-43-like immunoreactive (-IR) structures gathered densely in the subgemmal region. Some of these further penetrated the apical epithelium and trench wall epithelium. At least two types of GAP-43-IR structures were recognized; taste bud-related and non-gustatory GAP-43-IR neural elements. Immunoelectron microscopy revealed that GAP-43-LI was localized predominantly in the Schwann cells, and a few axons displayed GAP-43-LI in the lamina propria. In the trench epithelium, GAP-43-LI was detected in the cytoplasmic side of the axonal membrane. Some intragemmal GAP-43-IR axons made synaptic-like contacts with taste bud cells. At least four developmental stages were defined on the basis of the changes in distribution of GAP-43-LI. In stage I [embryonic day (E) 16-17] GAP-43-IR structures accumulated at the lamina propria just beneath the newly-formed circumvallate papilla. In stage II (E18-19) GAP-43-IR nerve fibers began to penetrate the apical epithelium. In stage III [E20-postnatal day (P) 0] GAP-43-IR nerve fibers first appeared in the trench wall epithelium. Penetration of GAP-IR nerve fibers occurred in the inner trench wall epithelium first, and then in the outer trench wall epithelium. In stage IV (P1-) the distribution of GAP-43-LI was similar to that observed in the adult; but the density of GAP-43-LI was much higher than in adults. PGP 9.5-LI showed a similar distribution pattern to that of GAP-43-LI, except for round-shaped cells in the apical epithelium at the late embryonic stages, and in taste bud cells and intralingual ganglionic cells which lacked GAP-43-LI. The similarities in distribution patterns of GAP-43-LI and PGP 9.5-LI during the development and mature circumvallate papilla suggest that GAP-43 may be a key neuronal molecule for induction and maintenance of the taste buds.

Animals↗
PubMed1998

Malignant mesothelioma originating in the hepatic falciform ligament: report of a case.

We report herein what to our knowledge is the first documented case of malignant mesothelioma arising from the falciform ligament. A 65-year-old woman was admitted to our department for the evaluation of an epigastric mass. An abdominal computed tomography scan, magnetic resonance imaging, and celiac angiogram showed a tumor originating in the falciform ligament. The tumor was subsequently resected, and pathological examination confirmed a diagnosis of malignant mesothelioma originating in the falciform ligament. A metastatic liver tumor was detected 3 years after this operation and a partial liver resection was performed. She is currently off therapy, and no clinical or radiologic evidence of disease has been found for 1 year since her second operation.

Aged↗
PubMed1998

Age-specific incidences of chromosome abnormalities at the second trimester amniocentesis for Japanese mothers aged 35 and older: collaborative study of 5484 cases.

The aim of this study was to calculate the expected incidences of chromosome abnormalities found at amniocentesis in Japanese women aged 35 and older. From four clinics in Japan, we gathered genetic amniocentesis data on 5484 pregnant women at risk only due to their advanced age, 35 years and older. We analyzed the data using the logistic regression model. Of the 5484 fetuses, 117 (2.1%) were diagnosed with a chromosome abnormality. The abnormal karyotypes included 42 cases of trisomy 21; 13 of trisomy 18; 7 of trisomy 13; 10 of 47,XXY; 4 of 47,XXX; 1 of 47,XYY; 27 with various structural aberrations; and 13 with various types of mosaicism. The incidences of trisomy 21, lethal autosomal aneuploidies (trisomy 18 and trisomy 13), and sex-chromosome abnormalities (XXY, XXX, XYY) increased with maternal age. Parameters of the regression equations with their standard errors were calculated and the expected incidences of chromosome abnormalities at each maternal age were derived. The expected incidences of chromosome abnormalities obtained in this study are the first data published for Japan and will be useful for the counseling of pregnant women. The incidence of trisomy 21 is not different from the rates published previously for Western countries. The incidences of chromosome abnormalities are not affected by race or by geographic factors.

Age Factors↗
PubMed1998

Experimental chronic infection induced in mice by Actinomyces israelii entrapped in alginate gel.

Tissue responses to experimentally induced actinomycotic lesions were investigated in mice by both light and transmission electron microscopy. Micro-organisms of Actinomyces israelii were entrapped in alginate gel and injected into the subcutaneous tissue over the periosteum of the mouse cranium. One day after the injection (initial stage), a non-stained amorphous structure was located in the core of the lesion, corresponding to the injected gel with bacteria. Numerous neutrophils surrounded the core region and phagocytized the injected complex actively. At days 3-7 (intermediate stage), the lesion became well developed. The core structure became eosinophilic and separated to form island-like structures. No lesion was recognized in the control group (gel without bacteria) until day 14. After 30 days (late stage), the lesions displayed more static features, similar to the "sulphur granules" characteristic of actinomycotic lesions. At the late stage, foamy cells increased in number and took the place of neutrophils in the alginate islands. By transmission electron microscopy these foamy cells were seen to be filled with lysosomal vesicles containing electron-dense foreign material. Thus, these cells appeared to be macrophages that had phagocytized degenerated neutrophils containing bacteria. Along with the active phagocytosis by foamy cells that progressed in the late stage, a collagenous capsule became conspicuous and separated the lesion from the intact tissue. The bacteria remained in the gel islands until at least day 60, although they considerably decreased in number with time. Serum IgG antibody titres began to rise within 24 h of the injection, reached a peak concentration at day 14 and remained a significantly high (p < 0.01, vs 0 time) until day 120. These results suggest that this animal model is useful for inducing experimental chronic infectious lesions.

Actinomyces↗
PubMed1998

Application of proton chemical shift imaging in monitoring of gamma knife radiosurgery on brain tumors.

Our objective was to assess proton chemical shift imaging for potential clinical application in monitoring response to gamma knife radiosurgery. Twenty-five proton chemical shift imaging studies and conventional magnetic resonance images were performed on six patients with intracranial tumors. The peak areas of N-acetylaspartate, choline-containing compounds (Cho), creatine, and lipids were calculated and normalized to N-acetylaspartate in the contralateral hemisphere. The spectra from the lesion before treatment showed a relatively high Cho peak, reported as a characteristic spectrum of tumors. Tumor size and Cho level after radiosurgery did not increase except in two cases. In these cases, radiation necrosis was observed with elevated Cho and a mobile lipid peak. Stable or decreased Cho seems to suggest a loss of tumor viability, and changes in Cho indicate the effectiveness of radiosurgery. Increasing Cho and the appearance of the mobile lipid peak may distinguish radiation necrosis from recurrent tumors, which cannot be distinguished by magnetic resonance imaging.

Adolescent↗
PubMed1998

Adenosquamous carcinoma of the tongue: report of a case with histochemical, immunohistochemical, and ultrastructural study and review of the literature.

A rare case of oral adenosquamous carcinoma in a 78-year-old woman is reported. The tumor occurred in her tongue and metastasized to the submandibular and cervical lymph nodes. Histologically, the tumor showed invasive growth involving the submucosal and muscle layers. Its solid carcinomatous nests exhibited ductal differentiation in the deeper aspects and squamous differentiation toward the surface. Histochemical examination revealed an accumulation of acid mucopolysaccharide in the ductal lumina, and the ductal cells were immunohistochemically positive for carcinoembryonic antigen, epithelial membrane antigen, cancer antigen 15-3 and Ulex europaeus agglutinin I. Ultrastructurally, tonofibrils, desmosomes and numerous cytoplasmic processes were common features of the tumor cells. In addition, true glandular structures and pseudocysts were seen in areas. Clinical features of 13 adenosquamous carcinomas in the literature were analyzed.

Aged↗
PubMed1998

An analysis of the prognostic significance of p53 status for squamous cell carcinoma of the oral cavity treated by radiotherapy.

The status of the p53 gene in biopsy specimens was analyzed to determine whether it is predictive of the outcome of radiotherapy of squamous cell carcinomas of the oral cavity. Biopsy materials were obtained from 45 patients, and the p53 status of each patient was determined using a single-strand conformation polymorphism analysis. Fourteen of the patients were treated with radiation therapy alone; the other 31 patients underwent radiotherapy in combination with surgery or chemotherapy. Twenty-seven patients had tumors with wild-type p53 and 18 patients had a tumor with mutant p53. The initial tumor response was not significantly different between these two groups. Kaplan-Meier survival plots (log-rank test) showed that the probability of survival was not significantly different between two groups although the patients with mutant p53 had a tendency for longer survival (P = 0.2941). However, among the patients with stage III/IV tumors (n = 24), those with a wild-type p53 status tended to have longer survivals.

Adult↗
PubMed1998

K-252a-induced polyploidization and differentiation of a human megakaryocytic cell line, Meg-J: transient elevation and subsequent suppression of cyclin B1 and cdc2 expression in the process of polyploidization.

Megakaryocytes are unique haemopoietic cells which undergo DNA replication, giving rise to polyploid cells. However, little is known about the mechanism of megakaryocytic polyploidization. To address this issue, we used the human megakaryocytic cell line Meg-J. In the presence of K-252a (an indolocarbasole derivative), Meg-J cells stopped proliferation and exhibited additional megakaryocytic features, including morphological changes, polyploidization, and increases in the levels of surface expression of platelet glycoprotein (GP) IIb/IIa and GPIb. Thrombopoietin (TPO) promoted the K-2 52a-induced polyploidization and megakaryocytic differentiation. In the process of K-252a-induced polyploidization, levels of expression of both cdc2 and cyclin B1 were elevated transiently and subsequently decreased. This suggested that the polyploidization process in Meg-J cells was at least in part associated with a transient elevation and subsequent decrease in the expression of cdc2/cyclin B1 complex, a critical kinase involved in G2/M cell cycle transition.

CDC2 Protein Kinase↗