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Biomedical subjects

Y Yoshimoto

Publications and source records attributed to Y Yoshimoto.

At least 73 records · Page 4Linked to original sources
PubMed1995

Methanol traps the troponin-tropomyosin-actin complex in an "off-state".

We have investigated the effect of methanol at concentrations below 15% (v/v) on acto-heavy meromyosin (HMM)- and tropomyosin (Tm)-troponin (Tn)-acto-heavy meromyosin-ATPase activities. Methanol slightly enhanced ATPase activity of acto-HMM alone. It had no apparent effect on normalized Tm-Tn-acto-HMM-ATPase activity in the absence of Ca2+. In the presence of Ca2+, however, methanol markedly inhibited normalized Tm-Tn-acto-HMM ATPase activity. These results show that methanol affects the troponin-tropomyosin regulation of acto-HMM ATPase: methanol suppresses the Ca(2+)-sensitivity of the regulatory system and traps it in an "off-state."

Actins↗
PubMed1995

Changes in epidermal growth factor receptor and the levels of its ligands during menstrual cycle in human endometrium.

We examined menstrual cycle-dependent changes in the expression of human endometrial epidermal growth factor (EGF), transforming growth factor alpha (TGF alpha), and epidermal growth factor receptor (EGFR) and their mRNA using immunoblot analysis, 125I-EGF binding, and competitive reverse transcription and polymerase chain reaction (RT-PCR). We also studied their localization in the endometrial tissue by immunohistochemistry. Endometrial samples were obtained at three stages of menstruation: the early follicular stage, which exhibits low serum estradiol (E2) and progesterone (P) levels; the late follicular stage, which exhibits high E2 and low P levels; and the luteal stage, which exhibits high E2 and P levels. Immunohistochemical examination showed that EGF, TGF alpha, and EGFR were localized to the endometrial epithelium. Immunoblot analysis revealed that endometrial EGF, TGF alpha, and EGFR levels were significantly (p < 0.01) increased at the late follicular and luteal stages compared to the early follicular stage. 125I-EGF-specific binding levels at the late follicular and luteal stages were significantly (p < 0.01) higher than at the early follicular stage, consistent with the results of immunoblot analysis. Competitive RT-PCR revealed that EGF, TGF alpha, and EGFR mRNA levels were significantly (p < 0.01) higher at the late follicular and luteal stages than at the early follicular stage. Changes in EGF, TGF alpha, and EGFR mRNA levels were consistent with changes in protein levels. These findings suggest that synthesis and expression of human endometrial EGF, TGF alpha, and EGFR vary with the stage of the menstrual cycle and that their expression in the human endometrium is associated with the increase in the serum E2 but not with the increase in P levels.

Binding, Competitive↗
PubMed1995

Increase in human placental glucose transporter-1 during pregnancy.

Glucose transporter-1 (GLUT1) has been found in high abundance in human placentas. The purpose of this study was to analyze the changes in the level of GLUT1 during pregnancy. We have analyzed the gestational changes in human placental GLUT1 by [3H]cytochalasin B binding assay, immunoblot analysis and Northern blot analysis. Levels of [3H]cytochalasin B binding to placental membrane in pregnancy at 7-10, 18-20 and 38-40 weeks were 4.2 +/- 0.47, 5.2 +/- 0.46 and 7.2 +/- 0.40 (mean +/- SEM, N = 4) mumol/kg protein, respectively. Amounts of 49-kD and 60-kD proteins detected in immunoblot analysis increased during pregnancy in parallel with [3H]cytochalasin B binding to placental membrane. The GLUT1 mRNA levels also increased during pregnancy. Immunohistochemical examination showed that GLUT1 was localized in the plasma membranes of trophoblast cells. These findings showed that the GLUT1 level increased during pregnancy in human placentas and suggest that GLUT1 may play an important role in fetal development.

Blotting, Northern↗
PubMed1995

Otoneurological observation and classification of Harada's disease presenting with aural symptoms, especially vertigo.

Harada's disease is an uncommon autoimmune disease affecting melanocytes located in the uvea, inner ear, skin, hair, and meninges. A classification of Harada's disease presenting with aural symptoms, especially vertigo, was devised on the basis of otoneurological findings. Peripheral vestibular dysfunction, such as staggering in the stepping test, rotato-horizontal or horizontal nystagmus, and diminished labyrinthine function in the caloric nystagmus test, was observed in the vast majority of these patients. Harada's disease with such features was designated as the peripheral type, and was further divided into vestibular, cochleo-vestibular, and cochlear subtypes. Patients only rarely presented with symptoms or signs of central nervous system involvement, and Harada's disease with such features was designated as the central type.

Adult↗
PubMed1995

Histologically verified cerebral aneurysm formation secondary to embolism from cardiac myxoma. Case report.

Multiple aneurysm formation secondary to an embolism from the cardiac myxoma is a well-known phenomenon. The cerebral arterial aneurysm formation process involved remains to be elucidated, although occupation of the arterial wall by tumor cells has been proven histologically. The authors present the case of a patient in whom tumor cells in the aneurysm wall were demonstrated and penetration of viable myxoma cells into the wall was also observed 19 months after surgical removal of the cardiac tumor. Such findings have never before been verified histologically. In light of the histological findings, the authors discuss the therapeutic problems associated with cerebral aneurysms resulting from cardiac myxoma.

Adult↗
PubMed1995

Functional changes in cultured strips of canine cerebral arteries after prolonged exposure to oxyhemoglobin.

The present study was undertaken to determine whether oxyhemoglobin (OxyHb) is responsible for the functional alterations in the cerebral arteries observed during chronic vasospasm after subarachnoid hemorrhage. Vascular strips of canine basilar arteries were kept in organ culture for 3 days with or without repetitive exposure to OxyHb (OxyHb-treated and control strips). Contractions elicited by high levels of potassium (80 mM) and uridine 5'-triphosphate (3 x 10(-4) M) were reduced in the OxyHb-treated group in a concentration-dependent manner. The relaxations evoked by nitric oxide and 8-bromo-cyclic guanosine monophosphate (8-bromo-cGMP) were not affected. Relaxations elicited by the calcium channel blocker, diltiazem, were attenuated in the OxyHb-treated rings. When the extracellular calcium concentration ([Ca2+]e) was changed from a concentration in the external solution of 10(-8) M to 10(-3) M, myogenic tension developed. Myogenic tension, expressed as a percentage of the maximum contraction in each segment, was augmented in the OxyHb-treated group at [Ca2+]e of 10(-5) M and 10(-4) M. There were no significant differences in passive compliance of the arterial wall between the two groups. These results demonstrated that prolonged exposure to OxyHb in vitro results in a decrease in contractile capacity and an increase in sensitivity to [Ca2+]e, in agreement with previous findings in spastic arteries. By contrast, impairment of the 8-bromo-cGMP-mediated relaxation pathway and increased stiffness of the arterial wall, which have been reported to occur in spastic arteries, were not induced by prolonged exposure to OxyHb in vitro.

Analysis of Variance↗
PubMed1995

Age-related multifactorial causes of neurological deterioration after early surgery for aneurysmal subarachnoid hemorrhage.

The factors contributing to neurological deterioration after early surgery for aneurysmal subarachnoid hemorrhage (SAH) were investigated. One hundred forty-two patients who underwent surgery within 3 days after SAH and recovered consciousness were divided into three age groups: 49 years of age or younger (Group A), 50 to 64 years old (Group B), and 65 years of age or older (Group C). Among these, 40 patients (28%) overall showed neurological deterioration; these cases were analyzed in detail. Although the highest incidence of deterioration was noted in patients in Group C (42%), angiographic vasospasm, quantified by measuring the change in the ratio of the diameters of the intracranial arteries to the extracranial internal carotid artery, was negatively correlated with age. In elderly patients, the severity of angiographic vasospasm was not related to the reversibility of symptoms or the outcome. At the time of aggravation, associated systemic complications such as cardiac decompensation, hypoxia, and electrolyte imbalance were noted in two (18%) of 11 patients in Group A, five (38%) of 13 in Group B, and eight (50%) of 16 in Group C, and these complications were significantly correlated with poor outcome in Group C. Although arterial narrowing is a leading cause of neurological deterioration after early aneurysmal surgery, the etiology is often multifactorial, especially in elderly patients, suggesting that hypervolemic therapy, which might provoke various complications, should be performed carefully under intensive monitoring.

Adult↗
PubMed1995

Prevalence rate of thyroid diseases among autopsy cases of the atomic bomb survivors in Hiroshima, 1951-1985.

To examine the radiogenic risk of latent thyroid cancer, thyroid adenoma, colloid/adenomatous goiter and chronic thyroiditis, the data for 3821 subjects collected in the course of autopsies of atomic bomb survivors in Hiroshima from 1951 to 1985 by the Radiation Effects Research Foundation (RERF) were analyzed using a logistic model. About 80% of the autopsies were performed at RERF and the remainder at local hospitals. The frequencies of the above diseases were not associated with whether the underlying cause of death was cancer. However, note that our results may be influenced by potentially biasing factors associated with autopsy selection. The relative frequency of latent thyroid cancer (greatest dimension < or = 1.5 cm but detectable on a routine microscopic slide of the thyroid gland) increased as the radiation dose increased and was about 1.4-fold greater at 1 Gy than in the 0-Gy dose group. The relative occurrence of thyroid adenoma also increased as radiation dose increased, and was about 1.5-fold greater at 1 Gy than in the 0-Gy dose group. Sex, age at the time of the bombing or period of observation did not significantly modify the radiogenic risks for thyroid adenoma or latent thyroid cancer. No statistically significant association was found between radiation exposure and the rates of colloid/adenomatous goiter and chronic thyroiditis. The possible late effect of atomic bomb radiation on the frequency of benign thyroid diseases is discussed on the basis of these data.

Adenoma↗
PubMed1995

Proliferative potential and malignant transformation of ganglioglioma: immunohistochemical studies by MIB-1 and p53 staining.

We studied two cases of ganglioglioma immunohistochemically by MIB-1 and p53 staining. The positive rate of MIB-1 in the ganglionic cells was 5.5% in Case 1 and 7.8% in Case 2, and that of MIB-1 in the gliomatous cells was 1.4 and 6.6% respectively. The labeling index of p53 in the ganglionic cells was 7.3% in Case 1 and 7.7% in Case 2, and that of the gliomatous cells was 1.9 and 3.4% respectively. MIB-1 and p53 did not stain ganglionic precursor cells. These results indicate that the ganglionic cells also take part in proliferation and have potential of malignant transformation.

Aged↗
PubMed1994

Tumor necrosis factor-alpha (TNF-alpha) inhibits expression of mouse placental lactogen-II through TNF-alpha type-I but not type-II receptor.

The aim of this study was to determine whether TNF-alpha inhibits mPL-II secretion through TNF-RI or TNF-RII, and to investigate the gestational profile of TNF-RI and TNF-RII gene expression. The mouse trophoblast cells from day 12 pregnancy were cultured with or without agonistic polyclonal antibodies directed against the individual TNF-alpha receptors, and mPL-II secretion in the medium was assessed by RIA. Anti-TNF-RI antibody significantly inhibited the mPL-II secretion in a dose- and time-dependent manner, but anti-TNF-RII antibody did not. Moreover, the TNF-RII antibody did not influence the inhibitory effect of the TNF-RI antibody on mPL-II secretion. TNF-RI antibody inhibited the mPL-II gene expression by Northern blot analysis. Amount of the gene expression of TNF-RI in the second half of pregnancy was higher than those in the first half of pregnancy both in vitro and in vivo, although the gene expression of TNF-RII was not detectable by Northern blot analysis using poly(A)+RNA. These results suggest that TNF-RI is a main receptor for TNF-alpha in mouse placenta and that TNF-alpha may have an important role in regulating mPL-II secretion after midpregnancy.

Animals↗
PubMed1994

Effect of host age upon the degree of nigrostriatal dopaminergic system recovery following cografts of adrenal medulla and pretransected peripheral nerve.

Accumulation of nerve growth factor (NGF) has been reported to occur at the distal stump of pretransected peripheral nerve. We performed adrenal medullary grafts or cografts of adrenal medulla and distal stump of pretransected peripheral nerve into the striatum of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated young or aging mice. We subsequently compared the survivability of chromaffin cells and the degree of host dopaminergic (DA) fiber recovery in relation to host age. In both young and aging hosts, adrenal medullary chromaffin cells cografted with pretransected peripheral nerve survived better than those in adrenal grafts alone. Host DA fiber recovery, however, showed less recovery and more restriction around the grafted site in aging compared with young hosts. We conclude that pretransected peripheral nerve can enhance the survivability of cografted chromaffin cells both in young and in aging hosts, but that DA fiber recovery is more limited in aging hosts compared to young hosts.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1994

High-performance capillary electrophoresis/frontal analysis for the study of protein binding of a basic drug.

A simple high-performance capillary electrophoresis (HPCE) method based on the principle of frontal analysis was applied to the determination of the concentration of unbound basic drug in protein binding equilibrium. A small volume of sample solution (approximately 80 nL) containing 113-340 microM of verapamil (VER) and 100-550 microM of human serum albumin was introduced into the fused silica capillary (effective length, 22 cm; 50-microns i.d.) by suction. Because the silanol groups on the inner surface of the capillary were bound with linear polyacrylamide through Si-C bonds, electroosmotic flow was not generated even at pH 7.4 with an applied voltage of +10 kV. The unbound drug bearing positive charge migrated electrophoretically from the drug-protein mixed zone toward the detection end, whereas human serum albumin did not co-migrate because of its negative charge. The bound drug migrated after it was released from the protein. As a result of an 80-nL injection of the sample solution, VER was eluted as a zonal peak with a plateau region. The VER concentration calculated from the plateau height agreed well with the unbound VER concentration determined by the conventional ultrafiltration-HPLC method, with good reproducibility (CV, < 6.23%, n = 15). The present HPCE/FA system was applied to the Scatchard analysis of VER and alpha 1-acid glycoprotein binding, and the estimated binding parameters agreed well with literature values.

Blood Proteins↗
PubMed1994

Muscarinic acetylcholine responses in the early embryonic chick retina.

The action of acetylcholine on cytoplasmic Ca2+ concentration ([Ca2+]i) was studied in early embryonic chick retinae. Whole neural retinae were isolated from embryonic day 3 (E3) chicks and loaded with a Ca(2+)-sensitive fluorescent dye (Fura-2). Increases in [Ca2+]i were evoked by the puff application of acetylcholine at concentrations higher than 0.1 microM. The Ca2+ response became larger in a dose-dependent manner up to 10 microM of acetylcholine applied. The rise in [Ca2+]i was not due to the influx of Ca2+ through calcium channels, but to the release of Ca2+ from internal stores. A calcium channel antagonist, nifedipine, which completely blocks the Ca2+ rise caused by depolarization with 100 mM K+, had no effects on the acetylcholine response and the Ca2+ response to acetylcholine occurred even in a Ca(2+)-free medium. The Ca2+ response to acetylcholine was mediated by muscarinic receptors. Atropine of 1 microM abolished the response to 10 microM acetylcholine, whereas d-tubocurarine of 100 microM had no effects. Two muscarinic agonists, muscarine and carbamylcholine (100 microM each), evoked comparable responses with that to 10 microM acetylcholine. The developmental change of the muscarinic response was examined from E3 to E13. The Ca2+ response to 100 microM carbamylcholine was intense at E3-E5, then rapidly declined until E8. The muscarinic Ca2+ mobilization we found in the early embryonic chick retina may be regarded as a part of the "embryonic muscarinic system" proposed by Drew's group, which appears transiently and ubiquitously at early embryonic stages in relation to organogenesis.

Acetylcholine↗
PubMed1994

Expression of epidermal growth factor and transforming growth factor-alpha in fallopian tube epithelium and their role in embryogenesis.

We studied the expression of epidermal growth factor (EGF) and transforming growth factor (TGF)-alpha in human fallopian tube epithelium at various menstrual stages. Immunohistochemical staining using anti-EGF and anti-TGF-alpha antibodies showed a specific staining in ampullary tube epithelium at late follicular and luteal stages but the staining was very weak at the early follicular stage. Quantitative reverse transcription and polymerase chain reaction (RT-PCR) using beta-actin mRNA as an internal standard revealed the menstrual-stage-specific expression of EGF and TGF-alpha gene transcripts: amounts of EGF and TGF-alpha mRNA relative to those of beta-actin were significantly higher at late follicular and luteal stages than at the early follicular stage. To clarify the biological role of these growth factors, mouse 2-cell embryos were cocultured with human fallopian tube epithelial cells with or without blocking the action of these growth factors. Cocultures significantly promoted blastocyst formation, but this promotive effect of the tubal epithelial cells was completely abolished by the addition of anti-EGF and/or anti-TGF-alpha monoclonal neutralizing antibodies to the coculture system. These results demonstrated that EGF and TGF-alpha were synthesized and expressed in fallopian tube epithelium at specific menstrual stages, and may be involved in early embryonic development.

Animals↗
PubMed1993

Xenogeneic dopaminergic grafts reverse behavioral deficits induced by 6-OHDA in rodents: effect of 15-deoxyspergualin treatment.

Foetal rat mesencephalic dopamine-containing tissue was transplanted into the lateral ventricle of mice previously subjected to a 6-OHDA lesion of dopaminergic nerve terminals in the corpus striatum. The graft recipients were immunosuppressed by subcutaneous injections of 15-deoxyspergualin (DSG). Four weeks postgrafting, all DSG-treated mice showed partial or complete functional compensation in amphetamine-induced motor asymmetry. The immunohistochemical staining of tyrosine hydroxylase (TH) revealed large numbers of surviving dopamine neurons and abundant fibers in the grafted animals. In contrast, all grafts in non-DSG-treated animals were rejected and functional compensation was lacking. It is concluded that DSG treatment promotes xenogeneic intracerebral graft survival, recovery of function and reduce the histological sign of rejection.

Amphetamine↗
PubMed1993

The influence of donor age on cografting of adrenal medulla with pretransected peripheral nerve.

Pretransected peripheral nerve has been demonstrated to enhance the survival of cografted adrenal medullary chromaffin cells and the recovery of host dopaminergic (DA) systems in animal models of Parkinson's disease. In the present study, we examined the effect of donor age on survival of cografted chromaffin cells. Adrenal medulla and pretransected peripheral nerve from young (1-month-old) or aging (12-month-old) donors were cografted into the striatum of MPTP-treated young (2-month-old) C57/BL mice. Although chromaffin cell survivability was increased by cografting with pretransected peripheral nerve despite donor age, survivability of chromaffin cells from aging donors was less than that using young donors. Image analysis of striatal DA fibers and chemical analysis of striatal DA showed that cografting with pretransected peripheral nerve enhanced the recovery of striatal DA systems more prominently than adrenal grafting alone. However, this effect was less in mice receiving aging donor tissues compared with mice receiving young donor tissues.

Adrenal Medulla↗