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T Yoshimoto

Publications and source records attributed to T Yoshimoto.

At least 415 records · Page 23Linked to original sources
PubMed1996

C-type natriuretic peptide as a possible local modulator of aldosterone secretion in bovine adrenal zona glomerulosa.

Although atrial and brain natriuretic peptides are well known to be involved in the regulation of cardiovascular and endocrine functions as circulating hormones, the roles of the C-type natriuretic peptide (CNP) remain unknown. We examined the effects of CNP on the secretion of aldosterone and cyclic nucleotides from bovine adrenal zona glomerulosa cells in culture. CNP produced a dose-dependent increase in the basal secretion of cGMP, with an EC50 of 3.8 x 10(-10)M. CNP significantly inhibited the ACTH-induced increase in aldosterone and cAMP in a dose-related manner, with an IC50 of 3.6 x 10(-10)M. Although ACTH itself did not increase cGMP secretion, the addition of CNP elicited a significant increase in cGMP secretion. The effects of CNP on the basal secretion of cGMP and the ACTH-induced secretion of aldosterone were significantly reversed by a nonpeptide natriuretic peptide receptor antagonist, HS-142-1. CNP immunoreactivity was localized in the zona glomerulosa by immunohistochemical staining. In addition, expression of CNP messenger RNA and natriuretic peptide B receptor messenger RNA was demonstrated by RT-PCR in the zona glomerulosa tissue and cells in culture. These findings suggest that CNP is a local factor regulating ACTH-induced aldosterone secretion through a guanylyl cyclase-cGMP pathway.

Adrenal Glands↗
PubMed1996

Vascular action of circulating and local natriuretic peptide systems is potentiated in obese/hyperglycemic and hypertensive rats.

Hypertension is commonly associated with diabetes mellitus. The aim of the present study was to explore the pathophysiological significance of the natriuretic peptide (NP) system in hypertension associated with genetically obese/hyperglycemic Wistar fatty rats. The messenger RNA (mRNA) levels of the two biologically active NP receptors, NP-A receptor [more specific for atrial natriuretic peptide (ANP)] and NP-B receptor [more specific for C-type natriuretic peptide (CNP)], and CNP mRNA levels were determined in the aorta and kidney by ribonuclease protection assay. Plasma ANP levels were determined by RIA. Both NP-A and NP-B receptor mRNA levels in the aortae of Wistar fatty rats were double those in Wistar lean rats. Plasma ANP levels and CNP mRNA levels in the aorta of Wistar fatty rats were also significantly higher than those in Wistar lean rats. In contrast, there was no significant difference in renal levels of the mRNA for both NP receptors and CNP between the two strains. Administration of a NP-A and -B receptor antagonist, HS-142-1, to Wistar fatty rats resulted in a significant increase in systolic blood pressure and a larger decrease in plasma cGMP level than that in Wistar lean rats, with no difference in the extents of decrease in urine volume and urinary sodium excretion between the two strains. These results suggest that both the ANP/NP-A system and the CNP/NP-B system in vessels are up-regulated at the level of gene expression and may, thus, play an important role in counteracting the hypertension associated with diabetes mellitus.

Animals↗
PubMed1996

Angiotensin II-dependent down-regulation of vascular natriuretic peptide type C receptor gene expression in hypertensive rats.

Biological actions of natriuretic peptide (NP) are determined by the condition of the receptor as well as that of the hormone. Although we previously demonstrated in hypertensive rats the up-regulation of NP-A receptor that mediates various biological actions of NPs, the pathophysiologic significance of NP-C receptor, another subtype thought to be related to clearance of NPs and possibly to biological actions, remains unknown. In the present study, we determined NP-C receptor messenger RNA (mRNA) level in the aortic tissue of stroke-prone spontaneously hypertensive rats (SHR-SP/Izm) and in cultured aortic smooth muscle cells by ribonuclease protection assay. The aortic NP-C receptor mRNA level in SHR-SP/Izm was significantly lower than that in the control WKY/Izm. Oral administration of an angiotensin (Ang) II receptor (AT1) antagonist, TCV-116, but not a calcium channel blocker, manidipine, reversed the down-regulated NP-C receptor mRNA in SHR-SP/Izm to the level in WKY/Izm, whereas the latter was more potent in decreasing the blood pressure. In cultured aortic smooth muscle cells, the NP-C receptor was the predominant subtype. Ang II decreased the NP-C receptor mRNA level in a dose-dependent manner, but this effect was reversed by an AT1 antagonist, CV-11974. Neither the NP-A nor NP-B receptor mRNA level was altered by Ang II. These findings indicate that vascular NP-C receptor is down- regulated via Ang-II-mediated mechanism in SHR-SP/Izm. The phenomenon, together with the up-regulation of the NP-A receptor, may play an important role in counteracting hypertension by enhancing the action of NPs.

Angiotensin II↗
PubMed1996

Nucleotide sequence of the gene encoding pepstatin-insensitive acid protease B, scytalidopepsin B, of Scytalidium lignicolum.

A chromosomal DNA fragment of Scytalidium lignicolum that encodes the mature enzyme region of acid protease B (Scytalidopepsin B), was cloned and its nucleotides sequenced. The fragment contained a 76-bp intron at the middle of the mature enzyme-coding region. The mature enzyme was composed of 206 amino acid residues with a molecular weight of 21,550. There were some discrepancies between the amino acid sequence deduced from these results and that previously established by protein sequencing.

Amino Acid Sequence↗
PubMed1996

Inhibin alpha, beta A and beta B subunit messenger ribonucleic acid levels in cultured rat pituitary: studies by a quantitative RT-PCR.

Recent studies have demonstrated that inhibins and activins both play not only endocrine roles but also local regulatory roles in gonadotoropin secretion. There has been controversy as to the subtype of rat pituitary inhibin/activin. We studied the levels of inhibin alpha, beta A and beta B subunit mRNAs by a quantitative reverse transcription-polymerase chain reaction (RT-PCR) and the changes in their levels by adding inhibin alpha, beta A and beta B mRNA antisense oligonucleotides and inhibin A, activin A or GnRH to cultured rat anterior pituitary cells. This study demonstrated the level of 3 mRNAs to be 1.6 x 10(-2), 0.75 and 3.4 x 10(-2) molecules/cell with a molar ratio of 1:50:2. A stimulatory role for activin B in FSH secretion was suggested as beta B mRNA antisense oligonucleotide decreased FSH secretion. The beta B mRNA level tended to be decreased by the addition of activin A, but the decrease was not statistically significant. GnRH did not affect alpha and beta B mRNA levels when administered singly. The level of beta A mRNA was not changed by any of the above treatments. In conclusion, the presence of inhibin alpha, beta A and beta B subunit mRNAs in the rat anterior pituitary with the greatest abundance of beta A was demonstrated by using RT-PCR. Activin B or activin AB may play important roles in FSH secretion in an autocrine or a paracrine fashion, and activin A may play an indirect role in FSH secretion.

Activins↗
PubMed1996

Intraoperative radiation therapy and chemotherapy for huge choroid plexus carcinoma in an infant--case report.

A 2-month-old boy presented with a huge choroid plexus carcinoma in the left cerebral hemisphere. Almost total resection of the tumor was achieved, but a remnant abruptly enlarged 5 months later, requiring reoperation. After radical resection of the tumor, intraoperative radiation (10 Gy) was delivered. Postoperative chemotherapy was performed with methotrexate and vincristine, selected on the basis of in vitro chemosensitivity testing. No recurrence of the tumor was detected 18 months after the second operation. Radical surgery with these adjuvant therapies may be a good method to control this aggressive disease in infants.

Antineoplastic Agents↗
PubMed1996

Intracellular adhesion molecule-1 and lymphocyte function-associated antigen-1 expression in a rat forebrain reperfusion model.

Activated leukocytes may be involved in the reperfusion injury of the brain. The expression of intracellular adhesion molecule-1 (ICAM-1) (CD54) and lymphocyte function-associated antigen-1 (LFA-1) (CD11a/CD18) are important for the interaction of activated leukocytes with the brain. Therefore, the expression of ICAM-1 in the cerebral vessels and LFA-1 on leukocytes were examined after reperfusion in a rat four-vessel occlusion model. Model rats underwent reperfusion (15, 30, and 60 min, and 6, 12, and 24 hrs) following 30 minutes of forebrain ischemia. Immunohistological staining for ICAM-1 and LFA-1 was performed in each subgroup. ICAM-1 expression increased after 1-hour reperfusion and persisted on the cerebral microvessels in both the subcortical region and the basal ganglia. Leukocytes stained by LFA-1 were observed in the capillary vessels after 6-hour reperfusion. Increased expression of ICAM-1 and LFA-1 were induced by reperfusion, and this may be important in reperfusion injury of the brain.

Animals↗
PubMed1996

Angiographic analysis of moyamoya disease--how does moyamoya disease progress?

Differences in the clinical presentation and angiographic stages of moyamoya disease were studied in 69 patients, 35 children (6.3 +/- 2.9 years old) and 34 adults (44.6 +/- 10.5 years old). The angiographic stage (Suzuki's stage) was compared between childhood and adulthood, ischemic onset and hemorrhagic onset, and female and male. The distribution of the angiographic stage was not very different, but was significantly shifted from stage III to stage IV in adult cases. The angiographic stage in patients with hemorrhagic onset was not significantly different from those with ischemic onset. There was no significant difference between females and males. Angiographic change is not very remarkable between pediatric and adult moyamoya disease. The angiographic stage does not directly correlate with the distinct clinical presentations between pediatric and adult moyamoya disease. Other factors such as cerebral blood flow demand and arteriosclerotic change seem to cause these differences.

Adolescent↗
PubMed1996

Spontaneous disappearance of arteriovenous malformation during staged treatment of multiple cerebral arteriovenous malformations--case report.

A 36-year-old male presented with aphasia and right hemiparesis due to the rupture of the larger of two arteriovenous malformations (AVMs) coexisting in the left hemisphere. The two AVMs had completely separate locations and different feeding arteries and draining systems. Two months after resection of the larger AVM and evacuation of the hematoma, carotid angiography showed the residual AVM had spontaneously disappeared. He was discharged without deficits. Change of cerebral hemodynamics after removal of the larger AVM presumably caused the spontaneous regression of the smaller one. Cerebral angiograms should be carefully examined because cerebral hemodynamics may be altered after removal of an AVM.

Adult↗
PubMed1996

[Travel outside the home and perceived problems with such travel, among elderly people in a small town].

To study travel outside the home by elderly people and perceived problems with such travel, a questionnaire was sent to 238 men and women aged 60-year-old and over living in a small town in Kanagawa prefecture. Public transportation in this town consists mainly of buses, and the bus ride from the nearest train station takes about 50 minutes. A total of 190 people responded (83.3%, after exclusion of those who had died, moved away, or were in the hospital). Of those 190 people, 166 (74 men and 92 women) went out by themselves and their responses were analyzed. About 50% of both men and women said that they go to the hospital once or twice a month and go out for hobbies less than several times a year. The means of transportation differed according to sex and age: 80% of men in their 60s said that they drive alone, but many men in their 70s and older said that they ride buses or walk. Women in all the age studied said that they ride buses or drive with others. More than 50% of men and women reported problems with transportation: men reported anxiety about driving alone and women reported difficulties with the poor means of transportation or when walking upstairs or uphill. Many men and women in their 80s said that they would rather not be driven places by others or be helped by others while riding trains or buses. These findings show the patterns of travel outside the home by elderly people of different ages, and the problems these people perceive with regard to various modes of transportation. They should be useful in the design of transportation suitable to older people.

Activities of Daily Living↗
PubMed1996

[Negative effect of perceived transportation problems on social activities of elderly people living in a small town far from the nearest train station].

Social activities such as visiting friends or participating in community groups have been shown to correlate positively with active health promotion, more frequent physical exercise, and maintenance of activities of daily living in older people. Social inactivity may result from personal factors such as physical condition and from environmental factors such as limited means of transportation. To study the latter factors, we focused on perceived transportation difficulties and on the influence of those perceptions on the daily activities of elderly people. We sought to test the hypothesis that perceived transportation problems restrict health promotion or social activities and accelerate the decline in activities of daily living, and also to determine how transportation can be improved. A questionnaire was sent to 238 people (a fifth of the population) aged 60 years or older who were living in a small town in Kanagawa prefecture. Buses are the principal mode of public transportation from their residences to the nearest train station and the trip takes about 50 minutes. Responses were received from 190 persons (83.3%, excluding those who had died, moved, or were in the hospital). Of the respondents, 166 (74 men and 92 women) went out by themselves and their responses were subjected to logistic regression analysis. The results revealed the following points. (1) For both men and women, riding buses to the hospital was associated with a greater perception of problems with respect to convenience, physical exertion, or anxiety when crossing the road. (2) Among women, greater perceived inconvenience of transportation correlated with a lower frequency of going out for daily shopping; a higher frequency of visiting friends correlated with greater perception of physical exertion. (3) Among women, the main desire was to visit friends. Men indicated that they wanted to be more active in hobbies. The women indicated that the main reason they do not fulfill their desires was that transportation is inconvenient. These findings indicate that perceived transportation problems can prevent elderly people, especially women, from going out for health promotion and social activities. This indicates that to support social activities of elderly people, the means of transportation should be made more convenient and more physically accessible, and local circumstances should be taken into consideration.

Activities of Daily Living↗
PubMed1996

Is "unilateral" moyamoya disease different from moyamoya disease?

Whether a diagnosis of moyamoya disease is justified in patients with typical angiographic evidence of moyamoya disease unilaterally and normal angiographic findings contralaterally remains controversial. In this study the authors analyzed longitudinal angiographic change, familial occurrence, and basic fibroblast growth factor (bFGF) concentration in the cerebrospinal fluid (CSF) of patients with "unilateral" moyamoya disease. Over a 10-year period, 10 cases of unilateral moyamoya disease were followed using conventional angiography or magnetic resonance angiography. Basic FGF in CSF, obtained from the subarachnoid space of the cerebral cortex during revascularization surgery, was measured in five cases. Among the 10 cases of unilateral moyamoya disease, only one pediatric case showed obvious signs of progression to typical bilateral disease. The other nine cases (including six adults and three children) remained stable throughout follow-up radiological examinations (magnetic resonance angiography) with a mean observation period of 3.5 years. There was no familial occurrence in these cases of unilateral moyamoya disease. Levels of bFGF, which are high in typical moyamoya disease, were low in these patients. The progression from unilateral moyamoya disease to the typical bilateral form of the disease appears to be infrequent. The low levels of bFGF in the CSF of these patients and the lack of familial occurrence strongly suggest that most cases of unilateral moyamoya disease, especially those found in adults, are distinct from typical bilateral moyamoya disease.

Adolescent↗
PubMed1996

A screening method for antimitotic and antifungal substances using conidia of Pyricularia oryzae, modification and application to tropical marine fungi.

A bioassay method detecting deformations of mycelia germinated from conidia of Pyricularia oryzae P-2b, has been modified to give quantitative estimations. The method was first developed using antimitotic agents which showed characteristic curling effect. Morphological deformations include curling, swelling, hyper-divergency, beads shape and so on, and inhibition of the germination was also observed. For quantitative estimations, indices were introduced for the hyphal growth inhibition and a quantity of conidia in each assay cell and concentration of test solutions were adjusted. Details of the modified method and the application to screening assay of marine fungi isolated in Yap Islands are described. Eight strains of 109 tested showed morphological deformations, and chaetoglobosin A was isolated from the broth filtrate of a strain assigned to Chaetomium sp. This bioassay is a cheap, quick and easy method to be applied to the primary screening for antimitotic and antifungal substances from natural sources.

Antifungal Agents↗
PubMed1996

Noninvasive evaluation of malignancy of brain tumors with proton MR spectroscopy.

PURPOSE: To test clinical proton MR spectroscopy as a noninvasive method for predicting tumor malignancy. METHODS: Water-suppressed single-voxel point resolved spectroscopy in the frontal white matter of 17 healthy volunteers and 25 patients with brain tumors yielded spectra with peaks of N-acetyl aspartate (NAA), choline-containing compounds (Cho), creatine/phosphocreatine (Cre), and lactate. These peak intensities were semiquantitated as a ratio to that of the external reference. The validity of the semiquantitation was first evaluated through phantom and volunteer experiments. RESULTS: The variation in measurements of the designated region in the volunteers was less than 10%. Normal ranges of NAA/reference, Cho/reference, and Cre/reference were 3.59 +/- 0.68, 1.96 +/- 0.66, and 1.53 +/- 0.64 (mean +/- SD), respectively. In 17 gliomas, the Cho/reference value in high-grade gliomas was significantly higher than in low-grade gliomas. Levels of NAA/reference were also significantly different in low-grade and high-grade malignancy. In eight meningiomas (four newly diagnosed and four recurrent), the level of Cho/reference was significantly higher in recurrent meningiomas than in normal white matter or in newly diagnosed meningiomas. CONCLUSIONS: Higher grades of brain tumors in this study were associated with higher Cho/reference and lower NAA/reference values. These results suggest that clinical proton MR spectroscopy may help predict tumor malignancy.

Adolescent↗
PubMed1996

[Right hemispheric dominancy in the auditory evoked magnetic fields for pure-tone stimuli].

It is well known that the auditory evoked N100m response is dominant in the contralateral hemisphere to the stimulated ear: N100m latency is shorter and N100m amplitude is larger in the contralateral hemisphere than the ipsilateral hemisphere. Interhemispheric asymmetry of the N100m responses were reported in terms of the equivalent dipole localization: the right hemispheric N100m dipole is more anterior to the left hemispheric dipole. In the present study, we investigated interhemispheric asymmetry of the auditory evoked P50m and N100m response in terms of signal amplitude. A helmet-shaped whole head magnetoencephalography system was employed to see small but significant differences between two hemispheres. Thirty-seven right-handed healthy subjects, 31 males and 6 females, participated in the study. The helmet-shaped whole head MEG system (CTF Systems-Osaka Gas) consists of an array of 66 MEG sensor sites uniformly distributed over the entire head. The monaural auditory stimuli, 2000 Hz tone burst of 50 msec duration were delivered to the left and then the right ear sequentially, with an intensity of 80 dB SPL at the ear. White noise of 50 dB SPL was delivered to the opposite ear. The inter-stimulus intervals were randomized in the range from 2.5 to 4.7 sec. In a total of 37 subjects, N100m dipole pattern appeared on both hemispheres either left or right ear stimuli. When P50m peak amplitude was compared between contralateral responses, the right-hemispheric response (141.5 +/- 16.3 fT, mean +/- s.e.m.) was slightly larger than the left-hemispheric response (134.3 +/- 10.2 fT). Differences, however, were not significant. When P50m peak amplitude was compared between ipsilateral responses, the right-hemispheric response (135.1 +/- 11.0 fT) was slightly larger than the left-hemispheric response (115.3 +/- 10.9 fT). Differences were not significant, either. When N100m peak amplitude was compared between contralateral responses, the right-hemispheric response (484.4 +/- 28.4 fT) was statistically (p < 0.01) larger than the left-hemispheric response (375.6 +/- 28.0 fT). When N100m peak amplitude was compared between ipsilateral responses, the right-hemispheric response (405.8 +/- 27.9 fT) was statistically (p < 0.02) larger than the left-hemispheric response (315.1 +/- 24.8 fT). Previously, we reported that the right hemispheric latency is shorter than the left hemispheric latency in the auditory evoked field N100m responses. Present study indicated another evidence of the right hemispheric dominancy in the auditory evoked responses, namely the lager amplitude in the right hemispheric response at least for pure-tone stimuli. The whole-head MEG system is suitable to analyze differences of auditory function between two hemispheres.

Acoustic Stimulation↗
PubMed1996

Neuromagnetic evidence that the P100 component of the pattern reversal visual evoked response originates in the bottom of the calcarine fissure.

Visual evoked magnetic fields due to pattern reversal stimuli were measured in 5 normal subjects using a helmet-shaped 66 channel magnetoencephalography system linked to MRI. The magnetic topography of the prominent 100 ms response (P100m) evoked by fullfield visual showed a double-dipole pattern in the occipital areas of all subjects. Right or left half-field stimuli and upper or lower quadrant-field stimuli evoked a single-dipole pattern in the contralateral occipital area. The P100m sources were then localized using a current dipole model and superimposed on MRI images of each subject. The visual cortex was morphologically variable among the subjects, but the P100m dipoles were all localized at the lateral bottom of the calcarine fissure. Moreover, these P100m dipoles had similar orientations for both half-or quadrant-field stimuli. These results suggest that the P100m is located in a smaller part of the striate cortex than previously reported.

Adult↗