Biomedical subjects

H Yorifuji

Publications and source records attributed to H Yorifuji.

At least 19 recordsLinked to original sources

PubMed1998

Ethidium bromide-induced inhibition of mitochondrial gene transcription suppresses glucose-stimulated insulin release in the mouse pancreatic beta-cell line betaHC9.

Recently, a mitochondrial mutation was found to be associated with maternally inherited diabetes mellitus (Kadowaki, T., Kadowaki, H., Mori, Y., Tobe, K., Sakuta, R., Suzuki, Y., Tanabe, Y, Sakura, H., Awata, T., Goto, Y., Hayakawa, T., Matsuoka, K., Kawamori, R., Kamada, T., Horai, S., Nonaka, I., Hagura, R., Akanuma, Y., and Yazaki, Y. (1994) N. Engl. J. Med. 330, 962-968). In order to elucidate its etiology, we have investigated the involvement of mitochondrial function in insulin secretion. Culture of the pancreatic beta-cell line, betaHC9, with low dose ethidium bromide (EB) (0.4 microg/ml) for 2-6 days resulted in a substantial decrease in the transcription level of mitochondrial DNA (to 10-20% of the control cells) without changing its copy number, whereas the transcription of nuclear genes was grossly unaffected. Electron microscopic analysis revealed that treatment by EB caused morphological changes only in mitochondria and not in other organelles such as nuclei, endoplasmic reticula, Golgi bodies, or secretory granules. When the cells were treated with EB for 6 days, glucose (20 mM) could no longer stimulate insulin secretion, while glibenclamide (1 microM) still did. When EB was removed after 3- or 6-day treatment, mitochondrial gene transcription recovered within 2 days, and the profiles of insulin secretion returned to normal within 7 days. Studies with fura-2 indicated that in EB-treated cells, glucose (20 mM) failed to increase intracellular Ca2+, while the effect of glibenclamide (1 microM) was maintained. Our system provides a unique way to investigate the relationship between mitochondrial function and insulin secretion.

Animals↗

PubMed1997

Subglottic branch of the superior laryngeal nerve in the dog penetrates the cricoid cartilage.

The topographic anatomical study on the distribution pattern of the superior laryngeal nerve (SLN) in the larynx was studied in thirteen adult dogs. The ramus posterior of the SLN divides into two branches; the interarytenoid branch (IA) and the pharyngoesophageal branch (PE). The IA on both sides connect to the cricoid ganglion (CG) in the midline at the cranial border of the cricoid cartilage. Posterior glottic branches arise from the IA, run over the cricoid cartilage, and distribute fibers to the posterior wall of the glottis. Every specimen observed in the present study possessed the CG and the posterior glottic branches. The subglottic branch derives from the IA near the cricoid ganglion, and passes through the cricoid foramen (CF) (Yoshida, 1986). The subglottic branch distributes fibers to the subglottic mucous membrane covering the cricothyreoid ligament. The CF and the subglottic branch were observed on both sides of seven specimens out of thirteen dogs. They were also observed on only one side in three specimens, and were not detectable on either side in the three remaining specimens. The silver impregnation applied in the semimicroscopic dissection facilitated identification of the precise localization and the topographic arrangement of ganglia and nerve bundles.

Animals↗

PubMed1997

X-ray microanalysis and phagocytotic activity of cultured retinal pigment epithelial cells in hypoxia.

PURPOSE: To investigate the influence of the functional and morphological changes induced in retinal pigment epithelial (RPE) cells by retinal ischemia, we evaluated the phagocytotic activity, the concentration of various elements, and ultrastructure in cultured RPE cells in hypoxia. METHODS: The concentrations of oxygen in incubators were adjusted to 20, 10, and 1% by the addition of nitrogen for 72 hr. To observe phagocytotic activity and its relationship to actin filaments, the filaments of RPE cells incubated with fluoresbrite carboxylate YG microspheres were stained with rhodamine phalloidin. Some of the specimens were subjected to X-ray microanalysis by scanning electron microscope after being fixed, freeze-dried, and coated with carbon to investigate the cytoplasmic concentration of elements. A part of the latter specimens was also observed by transmission electron microscope after being embedded in epon and cut into ultrathin sections to see the ultrastructural changes inside cell. RESULTS: Lowering oxygen concentrations from 20% to 1% swelled RPE cells and decreased the number of fluoresbrite carboxylate YG microspheres phagocytized by RPE cells. Phagocytosis of a large amount of latex beads (30 microl) for 24 hr in 1% oxygen caused a disruption of RPE cells. Na, S, and P were detected in RPE cells cultured in 20% oxygen. Reducing the oxygen concentration from 20 to 10 or 1% significantly decreased Na and increased S. Mitochondria were observed in RPE cells in 20 and 10% oxygen, but many vacuoles were observed in the cytoplasm in 1% oxygen. CONCLUSION: Hypoxia as low as 1% oxygen induced malfunction of phagocytosis and the fragility of RPE cells. We could speculate the imbalance of the electrolytes such as Na or a decrease of antioxidants such as glutathione containing S as a reason of disturbance of cell viability.

Actins↗

PubMed1996

Comparative effects of linoleic acid and linoleic acid hydroperoxide on growth and morphology of bovine retinal pigment epithelial cells in vitro.

PURPOSE: Outer segments of the photoreceptor rods that are phagocytized by the retinal pigment epithelial (RPE) cells contain a high proportion of polyunsaturated fatty acids (PUFA). PUFA are susceptible to lipid peroxidation. We hypothesized that the resulting peroxides could injure RPE cells leading to retinal degeneration. Accordingly, we compared the effects of linoleic acid (LA) and its hydroperoxide (LHP) on the growth and morphology of RPE cells using laser scanning microscopy and transmission microscopy. METHODS: We counted the number of RPE cells after incubation for 24 and 48 hrs with concentrations of LA or LHP of 0.035, 0.175, and 0.35 mM. To observe the actin filaments, cultured RPE cells were stained with rhodamine phalloidin. The cells were prefixed with 2% glutaraldehyde and postfixed in 1% osmium tetroxide. Specimens were embedded in Epon 812 after dehydration, and the ultrathin sections were doubly stained with 2% uranyl acetate and 2% lead acetate for examination by transmission electron microscopy. RESULTS: Exposure to LA or LHP produced dose-dependent damage to RPE cells with a significantly greater effects of LHP than LA. After incubation for 24 hrs with 0.35 mM LA, the number of vacuoles in RPE cells exceeded that observed in control RPE cells by 365 nm laser microscopy. Exposure to 0.35 mM LHP for 24 hrs produced a pycnotic nucleus, with diffuse and granular autofluorescences observed in and around it. Exposure of RPE cells to 0.35 mM LA for 24 hrs showed that the LA incorporated into the lysosomes was digested and released extracellularly from lysosomes via exocytotic vesicles. However, such exposure to LHP damaged the RPE cells, including the membranes in the pinocytotic vesicles. The packed membranes resembled myelin. CONCLUSIONS: While the LA incorporated into the lysosomes was released extracellularly, LHP persisted in the RPE cells, being observed as autofluorescent lipofuscin-like materials. LHP was cytotoxic, and caused damage to the membranes of pinocytotic vesicles and lysosomes.

Animals↗

PubMed1995

Physical dissociation of the TCR-CD3 complex accompanies receptor ligation.

Recent studies indicate that there may be functional uncoupling of the TCR-CD3 complex and suggest that the TCR-CD3 complex is composed of two parallel signal-transducing units, one made of gamma delta epsilon chains and the other of zeta chains. To elucidate the molecular mechanisms that may explain the functional uncoupling of TCR and CD3, we have analyzed their expression by using flow cytometry as well as immunochemical means both before and after stimulation with anti-TCR-beta, anti-CD3 epsilon, anti-CD2, staphylococcal enterotoxin B, and ionomycin. We present evidence that TCR physically dissociates from CD3 after stimulation of the TCR-CD3 complex. Stimulation with anti-CD3 resulted in down-modulation of TCR within 45 min whereas CD3 epsilon was still expressed on the cell surface as detected by flow cytometry. However, the cell surface expression of TCR and CD3 was not affected when cells were stimulated with anti-TCR-beta under the same conditions. In the case of anti-CD3 treatment of T cells, the TCR down-modulation appeared to be due to the internalization of TCR, as determined by immunoelectron microscopy. Immunochemical analysis of cells after stimulation with either anti-TCR or anti-CD3 mAbs revealed that the overall protein levels of TCR and CD3 were similar. More interestingly, the dissociation of the TCR-CD3 complex was observed with both treatments and occurred in a manner that the TCR and the associated TCR-zeta chain dissociated as a unit from CD3. These results provide the first report of physical dissociation of TCR and CD3 after stimulation through the TCR-CD3 complex. The results also suggest that the signal transduction pathway triggered by TCR may differ from that induced by CD3.

Animals↗

PubMed1995

A novel type of cell death of lymphocytes induced by a monoclonal antibody without participation of complement.

A monoclonal antibody, RE2, raised by immunizing a rat with cell lysate of a mouse T cell clone, was found to directly kill interleukin 2-dependent T cell clones without participation of serum complement. Fab fragments of RE2 had no cytolytic activity, while the cross-linking of Fab fragments with anti-rat immunoglobulin reconstituted the cytotoxicity. The cytotoxicity was temperature dependent: the antibody could kill target cells at 37 degrees C but not at 0 degrees C. Sodium azide, ethylenediaminetetraacetic acid, and forskolin did not affect the cytolytic activity of RE2, while the treatment of target cells with cytochalasin B and D completely blocked the activity. This suggested that the cell death involves a cytoskeleton-dependent active process. Giant holes on the cell membrane were formed within 5 minutes after the treatment with RE2, as observed by scanning electron microscopy. There was no indication of DNA fragmentation nor swelling of mitochondria during the cytolysis, suggesting that the cell death is neither apoptosis nor typical necrosis. The antibody also killed T cell lymphomas and T and B cell hybridomas only when these cells were preactivated with concanavalin A, lipopolysaccharide, or phorbol myristate acetate. Preactivated peripheral T and B cells were sensitive to the cytotoxicity of RE2, while resting T and B cells were insensitive. These results provide evidence for a novel pathway of cell death of activated lymphocytes by membrane excitation.

Animals↗

PubMed1995

Young female patient with testosterone-producing adrenocortical adenoma also showing signs of subclinical Cushing's syndrome.

A 28-year old female patient with virilization due to left adrenocortical adenoma was studied. The patient had clinical features of hyperandrogenism such as hirsutism and a low pitched voice, but not of hypercorticoidism. Plasma testosterone and dehydroepiandrosterone-sulfate (DHEA-S) were high. Although the basal plasma cortisol concentration and urinary excretion of 17-hydroxycorticosteroids (17-OHCS) were within the normal range, the absence of diurnal variation in plasma cortisol and loss of suppressibility by dexamethasone suggested constitutive secretion of cortisol by the tumor. Inappropriate cortisol secretion was also supported by blunted ACTH response to provocative stimuli. After successful removal of the left adrenal tumor, such endocrinological abnormalities were all normalized. Immunohistochemical analysis revealed that tumor cells were positively stained for C21 hydroxylase cytochrome P-450 (P-450C21) and P-450(11) beta which convert 17-hydroxy (OH) progesterone to cortisol as well as P-450SCC, 3 beta-hydroxysteroid dehydrogenase and P-450(17) alpha which are involved in testosterone biosynthesis. These findings suggest that adrenocortical adenoma secretes predominantly testosterone and constitutively cortisol in a young woman patient with virilization.

17-Hydroxycorticosteroids↗

PubMed1995

[Factor XIII].

Explore the source record for details and available documents.

Factor XIII↗

PubMed1994

Competition between motor molecules (kinesin and cytoplasmic dynein) and fibrous microtubule-associated proteins in binding to microtubules.

In neuronal cells, microtubule-associated proteins (MAPs) can be classified into two distinct groups. One consists of force-producing MAPs, the main components of which are kinesin and cytoplasmic dynein. The other is composed of fibrous MAPs, which include tau and MAP2. Many studies have been performed on the respective groups to understand their structures and functions. However, the problem of how the groups interact with each other on microtubules is still unresolved. To elucidate the interaction between kinesin or cytoplasmic dynein and tau or MAP2, we performed three experiments: competition, motility assay, and cosedimentation. To distinguish whether the binding competition is caused by steric hindrance of the projection domains of MAPs or by the competition of the binding sites on microtubules, we used microtubule binding domains of tau and MAP2 as well as native proteins. Our results revealed that kinesin or cytoplasmic dynein and tau or MAP2 complete for almost the same binding domains located on the carboxyl-terminal side of alpha- and the amino-terminal side of beta-tubulin from the site of subtilisin cleavage. Furthermore, the projection of tau, and probably of MAP2, might inhibit the binding of kinesin or cytoplasmic dynein to microtubules by steric hindrance. These findings will provide a useful step toward understanding the regulation system of intracellular organelle transport.

Animals↗

PubMed1994

Components of the mylohyoid nerve degenerate during evolutionary progress in primates.

The vibrissal, cutaneous and muscular branch of the mylohyoid nerve was studied on both sides in 67 individuals in 16 species of 14 genera (Rattus, Canis, Felis, Suncus, Talpa, Tupaia, Lemur, Nicticebus, Galago, Pithecia, Ateles, Papio, Macaca, Pan) with particular reference to the phylogenic change of these branches. In this series of studies in rats, dogs, cats, tree shrews, and 5 sides out of 30 crab-eating monkeys, a fine branch of the mylohyoid nerve proceeds to the vibrissal hair follicle. The vibrissal branch passes through the platysma and enters the vibrissal hair follicle at the middle of the body. It is conceivable that the intermandibular vibrissae had been reduced from the intermandibular skin during the phylogenic progress of prosimians. The vibrissal branch of the mylohyoid nerve may retire from the intermandibular region according to the disappearance of the intermandibular vibrissae. The cutaneous branches of the mylohyoid nerve were detectable in almost all of the specimens. The cutaneous branch seems to be retained despite the reduction of the intermandibular vibrissae in primates. It must be considered to retire from the intermandibular skin during the evolutional progress of the hominids. In spite of the alteration of the muscular arrangement, the mylohyoid nerve is preserved as the innervation to the anterior belly of the digastric muscle and to the mylohyoid muscle in all specimens examined.

Animals↗

PubMed1993

[Fluctuation of plasma levels of fibrinogen degradation products, fibrin degradation products and total fibrin/fibrinogen degradation products in patients with DIC].

Ten patients with disseminated intravascular coagulation syndrome (DIC) were analyzed using three enzyme linked immunosorbent assays (ORGANON TEKNIKA, Belgium) for fibrin degradation products (FbDP), fibrinogen degradation products (FgDP) and total fibrin/fibrinogen degradation products (TDP). A significant elevation in each parameter and a significant depression of FgDP/FbDP (g/b) ratio were observed in the patients in early stage of DIC, comparing with normal individuals (p < 0.001 and p < 0.01). These results suggested that both fibrinolysis and fibrinogenolysis were marked accelerated, with a superiority in fibrinolysis in those patients. The levels of these parameters decreased and the g/b ratio increased with the passage of the clinical courses in five patients who were improved. Although in five deteriorated cases, the levels were kept high and their g/b ratio showed low continuously. These findings suggested that separated monitoring of fibrinolysis or fibrinogenolysis was useful to study patients with DIC and g/b ratio could be regarded as a helpful indication of therapeutic effects.

Disseminated Intravascular Coagulation↗

PubMed1993

[Thrombocytopenia in HIV-1 seropositive hemophiliacs].

When platelet counts were compared in 1986 and 1992 in 117 anti-HIV antibody positive and negative hemophilia patients, a clear decrease was found in the positive group. In 1992 platelet counts < 150 x 10(9) were present in 23.5% of the positive group in contrast to 5.8% of the negative group. Comparing platelet counts with other clinical parameters, a positive correlation was found with cholinesterase and a negative correlation with IgG in both the positive and negative groups, while negative correlations with beta 2-microglobulin and platelet-associated IgG were found in only the positive group. These findings implicate the chronic liver dysfunction present in hemophilia patients, apart from HIV infection, in the decrease in platelet counts, with immunodeficiency playing an additional role in the positive group. In the treatment of a hemophilia B patient showing decreased platelet counts, these counts increased consistent with the administration of Acyclovir and Zidovudine. It was demonstrated that HSV-1 and HIV-1 antigen are present on the soluble platelets of this patient and are recognized by antibodies in the patient's serum.

Adolescent↗

PubMed1993

[Levels of serum lactate dehydrogenase and its isozymes with relation to clinical features of pneumocystis carinii pneumonia in acquired immunodeficiency syndrome patients].

The clinical courses of 9 patients with acquired immunodeficiency syndrome (AIDS) complicated by pneumocystis carinii pneumonia (PCP) were followed to investigate the clinical significance of the measurement of various parameters such as serum lactate dehydrogenase (LDH). The mean duration of symptoms before diagnosis was 20 days, and the median duration of therapy was 29.5 days. Serum LDH activity increased in 8 of 9 cases. The isozyme pattern in all cases was characterized by high LDH3 values from the early stage. However, inflammatory markers did not increase in most cases. There were good correlations between the levels of LDH, clinical course, and PaO2.

AIDS-Related Opportunistic Infections↗

PubMed1992

The phosphorylation of kinesin regulates its binding to synaptic vesicles.

Membrane organella are transported bidirectionally in cells, and the axonal transport system has provided an ideal model system for studying this bidirectional transport. Kinesin and cytoplasmic dynein were identified as candidates for the motor molecules of fast axonal transport, which transport organella along microtubules anterogradely and retrogradely. However, the mechanism that controls this bidirectional transport is unknown. Our previous work revealed that kinesin in axons was associated abundantly with anterogradely transported membranous organella, most of which are believed to be precursors of synaptic vesicles and axonal plasma membranes, while the fractions bound to retrogradely transported ones were very small (Hirokawa, N., Sato-Yoshitake, R., Kobayashi, N., Pfister, K. K., Bloom, G. S., and Brady, S. T. (1991) J. Cell Biol. 114, 295-302). Here we demonstrated in vitro that the binding of kinesin to synaptic vesicles was concentration-dependent and saturable and could be released by high salt concentration. When kinesin was phosphorylated by cAMP-dependent protein kinase, its binding to symaptic vesicles was significantly reduced. By motility assay and by statistical analysis using electron microscopy, we further revealed that synaptic vesicles preincubated with phosphorylated kinesin associated less frequently with microtubules than synaptic vesicles preincubated with unphosphorylated kinesin. The phosphorylation of kinesin should therefore play an essential role in regulating the direction of fast axonal transport by inhibiting its binding to membrane organella, thus releasing it from membrane organella at nerve terminals.

Animals↗

PubMed1992

Herpes simplex virus type 1 and human immunodeficiency virus type 1 antigens in platelets from a hemophilia B patient with human immunodeficiency virus type 1-related thrombocytopenia.

We analyzed platelet-associated antigens from a hemophilia B patient with human immunodeficiency virus type 1 (HIV-1)-related thrombocytopenia. Two bands appeared at 31,000 and 37,000 daltons in the platelet lysate after reaction with autologous serum in SDS-PAGE and Western blots. The band at 37,000 daltons was obtained using anti-herpes simplex type 1 (HSV-1) rabbit antiserum. Doublet bands at 36,000 and 37,000 daltons also appeared after reaction with HSV-1 seropositive human serum. The band at 31,000 daltons appeared after reaction with anti-HIV-1 rabbit serum. These results suggest that the platelet-associated antigens in this patient are components of both HSV-1 and HIV-1 antigens. In addition, acyclovir decreased his PAIgG level and increased his platelet count, and zidovudine increased his platelet count. Thus, we concluded that each of the platelet-associated antigens is partially responsible for the thrombocytopenia by causing deposition of immune complexes in this patient.

Acyclovir↗

PubMed1992

[HIV-1 seropositive hemophilia A complicated by disseminated intravascular coagulation syndrome and acute pancreatitis during treatment of Pneumocystis carinii pneumonia].

Pneumocystis carinii pneumonia (PCP) is a major opportunistic infection in acquired immunodeficiency syndrome (AIDS) and is treated with co-trimoxazole, pentamidine and others. The severe adverse reactions, including bone marrow suppression, by these therapeutic agents often preclude their continued use. A 14-year-old male HIV-positive hemophilia A patient, who was complicated by disseminated intravascular coagulation syndrome (DIC) following acute pancreatitis during treatment for PCP, was treated with proteinase inhibitors and anticoagulant agents. He was improved and discharged. As pentamidine may cause pancreatitis and develop DIC, it is important that pancreatic enzymes should be carefully followed when this agent administrated. In this case, granulocyte colony-stimulating factor and erythropoietin were effective for the bone marrow suppression, suggesting that importance of these agents for the prophylaxis of other secondary infections during the treatment.

AIDS-Related Opportunistic Infections↗

PubMed1991

[Evaluation of an enzyme immunoassay for plasma thrombomodulin].

Thrombomodulin (TM) is an endothelial cell membrane glycoprotein which neutralizes thrombin clotting activity and accelerates thrombin-catalyzed activation of plasma protein C. Its role is considered to be very important to prevent thrombosis. Recently, TM has been found in circulating blood and the roles and the functions have been investigated. In this study, we evaluated the reliance and the clinical usefulness of a TM-measuring-kit by enzyme immunoassay (MGC-01-001: Mitsubishi Gas chemical company). Intraassay reproducibility test, dilution linearity test and in vitro recovery test was obtained satisfactory results. A correlation between plasma and serum on TM levels of healthy individuals was very good and the difference between them was not significant. Normal value of plasma TM levels was instituted 15.73 +/- 6.98 ng/ml by measuring 52 healthy adults. The difference between male and female was not significant. Plasma TM levels did not change significantly after venous occlusion test and on circadian fluctuation. Plasma TM levels in patients with occlusion test and on circadian fluctuation. Plasma TM levels in patients with disseminated intravascular coagulation (DIC) was 40.15 +/- 22.68 ng/ml (mean +/- SD, n = 14). It is significantly higher than the levels in healthy adults. However, the levels in patients with angina pectoris, acute myocardial infarction and aortic aneurysm were not significantly different from those of healthy adults. These findings suggest that the precision of this TM-measuring-kit is satisfactory and the measurement of plasma TM can be useful to diagnose of DIC.

Adult↗

PubMed1991

[Differentiation between fibrin degradation products and fibrinogen degradation products by using newly developed ELISAs].

We should distinguish fibrin degradation products (FbDP) from fibrinogen degradation products (FgDP) in order to analyze fibrinolysis in vivo. We analyzed some disorders associated with hyperfibrinolytic states using ELISA for FbDP, FgDP and total fibrin (ogen) degradation products (TDP) (ORGANON TEKNIKA). Each ELISA was useful in terms of reproducibility and dilution linearity of plasma samples. There was no cross-reaction between FbDP and FgDP. The FgDP/FbDP ratio in normal individuals was 1.65. In patients with DIC, it was 0.43, with FgDP level being increased. These results suggest that fibrinolysis is enhanced in patients with DIC, but it is accompanied by fibrinogenolysis. On the other hand, the FgDP/FbDP ratio in patients given urokinase (UK) was 2.88. This suggests that fibrinogenolysis is enhanced in them. In our study, the FgDP/FbDP ratio increased as DIC improved. Thus, we can regard this as an index of therapeutic effects in patients with DIC. We conclude that these three ELISA are useful in analyzing disorders associated with hyperfibrinolytic states.

Disseminated Intravascular Coagulation↗