Biomedical subjects

Y Yoshida

Publications and source records attributed to Y Yoshida.

At least 307 records · Page 17Linked to original sources

PubMed1999

Development of intraepithelial T lymphocytes in the intestine of irradiated SCID mice by adult liver hematopoietic stem cells from normal mice.

BACKGROUND/AIMS: We recently reported the adult mouse liver to contain c-kit+ stem cells that can give rise to multilineage leukocytes. This study was designed to determine whether or not adult mouse liver stem cells can generate intraepithelial T cells in the intestine as well as to examine the possibility that adult liver c-kit+ stem cells originate from the fetal liver. METHODS: Adult liver mononuclear cells, bone marrow (BM) cells, liver c-kit+ cells or bone BM c-kit+ cells of BALB/c mice were i.v. transferred into 4 Gy irradiated CB17/-SCID mice. In other experiments, fetal liver cells from Ly5.1 C57BL/6 mice and T cell depleted adult BM cells from Ly5.2 C57BL/6 mice were simultaneously transferred into irradiated C57BL/6 SCID mice (Ly5.2). At 1 to 8 weeks after cell transfer, the SCID mice were examined. RESULTS: Not only BM cells and BM c-kit+ cells but also liver mononuclear cells and liver c-kit+ cells reconstituted gamma delta T cells, CD4+ CD8+ double-positive T cells and CD8 alpha+beta- T cells of intestinal intraepithelial lymphocytes of SCID mice. Injection of a mixture of fetal liver cells from Ly5.1 C57BL/6 mice and adult BM cells from Ly5.2 C57BL/6 mice into Ly5.2 C57BL/6 SCID mice induced both Ly5.1 and Ly5.2 T cells, while also generating c-kit+ cells of both Ly5.1 and Ly5.2 origins in the liver. CONCLUSIONS: Adult mouse liver stem cells were able to generate intestinal intraepithelial T cells of the SCID mice, and it is thus suggested that some adult liver stem cells may indeed be derived from the fetal liver.

Animals↗

PubMed1999

Immunomodulating activity of seaweed extract on human lymphocytes in vitro.

Effect of eight kinds of seaweed extract (SWE) on human lymphocytes was studied in vitro. The extracts of Hizikiafusiformis and Meristotheca papulosa (green) markedly stimulated human lymphocytes to proliferate, whereas Eucheuma muricatum and Meristotheca papulosa (red) weakly stimulated proliferation. The responder cells are T cells, because T cells purified by sheep red blood cell (SRBC) rosette-formation were significantly stimulated with SWE, but B cells were not. These extracts enhanced the induction of cytotoxic T lymphocyte (CTL) activity, but failed to enhance natural killer (NK) cell activity. These extracts had a stimulatory effect on immunoglobulin (Ig) production by B cells and tumor necrosis factor (TNF) production by monocytes. The activity of Hizikia fusiformis associated with polysaccharides which were extracted with ethanol and purified by ion-exchange and gel filtration chromatography, whose molecular weight was about 100 kDa. These results suggest that SWE has an immunomodulating activity on human lymphocytes and this ability might be useful for clinical application to treat several diseases such as tumors.

Adjuvants, Immunologic↗

PubMed1999

Stimulating activity of Chinese medicinal herbs on human lymphocytes in vitro.

The effects of eight kinds of Chinese medicinal herbs (CMH) on human lymphocytes was studied in vitro. The extract of Cinnamomum cassia presl markedly stimulated human lymphocytes to proliferate. Codonopsis pilosula, Oldenlandia diffusa and Rhizoma typhonii weakly stimulated. These extracts enhanced cytotoxic T-lymphocyte (CTL) activity, but failed to enhance natural killer (NK)-cell activity. The extracts of these CMHs have stimulatory effect on immunoglobulin (Ig) production by B-cells and interleukin(IL)-1 production by monocytes. These activities of Cinnamomun cassia presl extract are associated with glycoproteins, whose molecular weight was about 100 KDa. These results suggest that CMH extracts have a stimulating activity on human lymphocytes and these abilities could be used clinically for the treatment of diseases such as cancer.

Adjuvants, Immunologic↗

PubMed1999

IP3 production in A10 cells, an established aortic smooth muscle cultured cell line: effects of agonist administration procedure and culture conditions.

1. After normal culture (10% FBS), medium exchange itself evoked marked increases in IP3 levels in A10 cells that masked the net change in IP3 in response to vasopressin (100 nM). 2. Low-serum (0.3% FBS) culture for 10 days abolished the increase in IP3 by medium exchange, and increased expression of cGMP kinase. 3. Stimulation of cells with vasopressin (100 nM) by a pipetting procedure, increased IP3 levels irrespective of culture conditions. 4. This cell line therefore could be used in a contractile form (after low-serum culture) with pipetting procedure to observe IP3 response, especially with regard to interactions with the cGMP signaling system.

Animals↗

PubMed1999

A new method for magnetoencephalography: a three-dimensional magnetometer-spatial filter system.

A novel three-dimensional magnetometer-spatial filter system was developed to study human brain activity with high spatiotemporal resolution. The system combines the high temporal resolution of magnetoencephalography with the high spatial resolution achieved by using three-dimensional magnetometers and spatial filters to measure the direction and intensity of magnetic fields generated during brain activity. Simulation and phantom studies indicate that the system is capable of mapping current sources of magnetic fields with a spatial resolution comparable to that of any other brain functional imaging technique while maintaining millisecond temporal resolution. Application of this system to the human brain resolved magnetoencephalographic responses evoked by motion stimuli on a millisecond scale into responses occurring in visual cortical areas V1, V2/3 and V5. It also revealed signals related to contextual modulation in V1 and V2/3. This system provides a new way of studying the dynamics of human brain function.

Brain↗

PubMed1999

Fentanyl increases dopamine release in rat nucleus accumbens: involvement of mesolimbic mu- and delta-2-opioid receptors.

The effects of the mu-receptor agonist fentanyl on extracellular levels of dopamine in rat nucleus accumbens were studied in awake animals by in vivo brain microdialysis. Fentanyl dose-dependently increased the levels of dopamine when given intravenously (microg/kg) or via a microdialysis probe placed into the ventral tegmental area or the nucleus accumbens (nmol). The effect of fentanyl given into the nucleus accumbens was blocked by systemic administration of the non-selective opioid receptor antagonist naloxone and by accumbens administration of D-Phe-Cys-Tyr-D-Trp-Om-Thr-Phe-Thr-NH2 (nmol), a mu-opioid receptor antagonist, and naltrindole (nmol), a non-selective delta-opioid receptor antagonist, in a dose-dependent manner. The delta2-opioid receptor antagonist, naltriben (nmol), also blocked the effects of fentanyl, whereas the delta1-opioid receptor antagonist, (E)-7-benzylidenenaltrexone (nmol), was ineffective. When marginally effective doses of D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Phe-Thr-NH2 and naltriben were given simultaneously, the effect of fentanyl was nearly fully blocked; the pretreatment itself had no effect. Administration of the mu-opioid receptor agonist [D-Ala2, N-Me-Phe4,Gly5-ol]-enkephalin (nmol), the delta1-opioid receptor agonist [D-Pen2,5]-enkephalin (nmol) or the delta2-opioid receptor agonist [D-Ala2,Glu4]-deltorphin (nmol) into the nucleus accumbens enhanced the amount of accumbal dopamine. This study provides evidence that not only activation of delta1- and delta2-opioid receptors, but also activation of mu-opioid receptors in the nucleus accumbens increases the release of accumbal dopamine in freely moving rats. We suggest that the effect of intra-accumbens administration of fentanyl upon accumbal release of dopamine is either due to the simultaneous activation of mu-opioid receptors and delta2-opioid receptors or due to activation of mu-opioid receptors that interact with delta2-opioid receptors in a complex manner.

Analgesics, Opioid↗

PubMed1999

Two cases of piriform sinus fistula which required a long time for diagnosis.

Two cases of piriform sinus fistula which had contradistinctive occurrences, were reported. In case 1, a 58-year-old man suffered from the disease without having any symptom for a long time and in case 2, a 39-year-old woman had been troubled with repeated cervical abscess from 3 years old. In both cases, indirect laryngoscopy and laryngofiberscopy showed saliva pooling in the bilateral piriform sinus and barium fluoroscopy with the Valsalva maneuver revealed the fistula originating from the apex of left piriform sinus. In case 2, computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated an abscess in and around the left lobe of the thyroid. In both cases the fistulectomy was performed and their postoperative conditions have been uneventful for more than 2 years without recurrence. The etiology, cause, clinical features, diagnosis and therapy of piriform sinus fistula were reviewed.

Adult↗

PubMed1999

An ultrastructural study of the effects of bisphosphonate administration on osteoclastic bone resorption during relapse of experimentally moved rat molars.

This study was designed to clarify the effects of systemic administration of bisphosphonate, pamidronate, on the bone resorbing activity of osteoclasts during relapse of rat molars, after experimental movement. An elastic band was inserted between the upper first and second molars of 7-week-old rats and removed 21 days later. At 1 day before elastic band removal, bisphosphonate was administered via a tail vein. After elastic band removal, the rats were further maintained for 0, 5, or 10 days. The relapse of the first molars was studied by means of light and scanning-electron and transmission-electron microscopy. When an elastic band was removed, the mean interdental distance between the first and second molars in all rats was approximately 435 micrometer. In the control rats, it had decreased to 108 micrometer by day 5 and 57 micrometer by day 10. In these control rats, numerous osteoclasts appeared along the alveolar bone surface in the compressed side of the periodontal ligament of first molars. Administration of bisphosphonate significantly inhibited the prominent decrease in interdental distance. In these rats, it averaged 313 micrometer at day 5 and 115 micrometer at day 10. In bisphosphonate-treated rats, osteoclasts aggregated mainly in vascular canals of alveolar bone but were occasionally observed along the alveolar bone surfaces facing the periodontal ligament. Administration of bisphosphonate also induced structural changes, such as disappearance of ruffled borders and cytoplasmic polarity, in osteoclasts. A degenerated osteoclast was also observed in a bisphosphonate-treated rat. However, bisphosphonate induced no structural changes in osteoblasts, osteocytes, or periodontal ligament fibroblasts. These results suggest that a single systemic administration of bisphosphonate decreases the extent of initial relapse in experimentally moved rat molars via a mechanism involving impairment of the structure and resorptive functions of osteoclasts.

Alveolar Bone Loss↗

PubMed1999

Effects of the phosphorylation of myosin phosphatase by cyclic GMP-dependent protein kinase.

Cyclic GMP-dependent protein kinase (PKG) phosphorylated, in vitro, the large (MYPT1) and small (M20) regulatory subunits of myosin phosphatase (MP) with maximum stoichiometries of 1.8 and 0.6 mol of phosphate/mol subunit, respectively. The phosphorylation of these subunits by PKG did not affect the phosphatase activity towards the 20 kDa myosin light chain. However, phosphorylation of the MP holoenzyme decreased the binding of MP to phospholipid. The phosphorylation of the serine residue of the C-terminal part of MYPT1 was crucial for these interactions. These results suggest that the phosphorylation of MP by PKG is not a direct mechanism in activating MP activity, and that other indirect mechanisms, including the interaction between MP and phospholipids, might be candidates for Ca2+ desensitization via cGMP in smooth muscle.

Animals↗

PubMed1999

Studies on anti-Helicobacter pylori agents. Part 1: Benzyloxyisoquinoline derivatives.

The synthesis and optimization of the anti-Helicobacter pylori activity of a novel series of benzyloxyisoquinoline derivatives that was discovered by a random screening process, are described. In the in vitro assay, compound 10c containing a 3-acetamido-2,6-dichlorobenzyl substituent was found to have extremely potent activity against H. pylori and no activity against other common bacteria. The anti-H. pylori activity of 10c was superior to that of amoxicillin (AMPC) (1) and clarithromycin (CAM) (2). However, 10c did not show in vivo efficacy in a mouse infection model; a feature attributed to the lack of strong bactericidal activity at short contact times.

Amoxicillin↗

PubMed1999

Crosstalk Among Multiple Signaling Pathways Controlling Ovarian Cell Death.

Ovarian cell death is an essential process for the homeostasis of ovarian function in human and other mammalian species. It ensures the selection of the dominant follicle and the demise of excess follicles. In turn, this process minimizes the possibility of multiple embryo development during pregnancy and assures the development of few but healthy embryos. Degeneration of the old corpora lutea in each estrous/menstrual cycle by programmed cell death is essential to maintain the normal cyclicity of ovarian steroidogenesis. Although there are multiple pathways that can determine cell death or survival, crosstalk among endocrine, paracrine and autocrine factors, as well as among protooncogenes, tumor suppressor genes, survival genes and death genes, plays an important role in determining the fate of ovarian somatic and germ cells. The establishment of immortalized rat and human steroidogenic granulosa cell lines and the investigation of pure populations of primary granulosa cells allows systematic studies of the mechanisms that control steroidogenesis and apoptosis of granulosa cells. These cells are the most abundant type of somatic follicular cell. Moreover, crosstalk between p53 and extracellular matrix components such as laminin, fibronectin and basic fibroblast growth factor, between cAMP- and p53-generated signals and between steroid hormones and Bcl-2, can explain some of the fine tuning that controls ovarian steroidogenesis and apoptosis. Further study of the mechanisms of ovarian cell death will lead to a better understanding of the processes involved and permit the formulation of novel strategies for the treatment of ovarian malfunctions, such as polycystic ovarian syndrome and ovarian cancer.

Journal Article↗

PubMed1999

Effect of tannic acid solution on collagen structures for dental restoration.

This study examined the effect of tannic acid solution on dissolution of dentine collagen and morphological aspects of tendon collagen. Using root dentine, which was cut off from bovine anterior tooth, dentine powders were obtained by the pulverization and lyophilization. They were subject to an application of 1, 3, 5 or 10% tannic acid (TA) solution for 1, 3, 6, 12 or 24 h. TA-treated dentine powders were treated with 40% phosphoric acid (PA) for 30 s at 20 degrees C and additionally with trypsin. Released hydroxyproline in Woessner's assay after a hydrolysis in 6 N HCl at 110 degrees C for 20 h was assumed to be dissolved dentine collagen. Released hydroxyproline in a control sample without acid treatment decreased from 100 to about 60% with increased TA concentration of 1 to 10%, and decreased with increased incubation times of 1 to 24 h when applied by 5% TA solution. Scanning electron microscopy results established the morphological effect of their surface characteristics due to such treatments as 40% PA for 30 s and 5% TA for 6 h, or 40% PA after 5% TA treatment, yielding collagen structures protected by TA to attack from phosphoric acid.

Journal Article↗

PubMed1999

Adeno-retroviral chimeric viruses as in vivo transducing agents.

Several hybrid viral gene transfer systems have been described that exploit the favorable features of the two parent viral species. We have developed a hybrid adeno-retroviral vector system to generate a retroviral vector in situ. The system consists of adenoviruses encoding MoMLV gag.pol (Axtet.gag.pol), the VSV-G viral envelope (Axtet.VSV-G), the retroviral vector LXSN expressing the neomycin phosphotransferase gene (AV-LXSN) and a transcriptional regulator to control expression of gag.pol and envelope (AV-rtTA). In vitro, biologically active retroviral vector preparations were generated following adeno-retroviral transduction of 9L rat glioma cells. In vivo the transcomplementing adeno-retroviruses were co-administered intratumorally into subcutaneous 9L glioma tumors in rats and human A375 melanoma xenografts in nude mice. In the 9L rat model, G418 cell cultures were only obtained when 9L cells were harvested from tumors injected with all four transcomplementing adeno-retroviruses. Molecular analysis of DNA extracted from 9L G418 populations derived both in vitro and in vivo showed appropriate integration of the LXSN proviral sequence. Tumor cells were harvested 1, 3 and 4 weeks after adeno-retrovirus administration to the human A375 xenografts. The percentage of G418 colonies recovered from tumors transduced with all of the transcomplementing adeno-retroviruses increased with time, whereas no increase was observed in tumors transduced with AV-LXSN alone. DNA extracted from G418 A375 cell populations showed the presence of integrated proviral sequences only in animals that received the full complement of adeno-retroviruses. These results demonstrate that adenoviral vectors expressing transcomplementing genes for retroviral proteins and retroviral vector RNAs can be used for in situ transduction of target cells.

Adenoviridae↗

PubMed1999

Trends in blood pressure and urinary sodium and potassium excretion in Japan: reinvestigation in the 8th year after the Intersalt Study.

Using the identical protocol of an Intersalt Study previously conducted, we undertook a new study (Intersalt-2) 8 years later. We measured changes in various factors affecting blood pressure (BP) including urinary sodium and potassium excretion in three districts of Japan: Osaka, Tochigi, and Toyama. Also we evaluated the trends in the relationships of those factors to BP. The Intersalt Study revealed that the average sodium excretion of all three study centres was high (particularly in Toyama) while potassium excretion was relatively low. The sodium/potassium ratio was therefore relatively high. The body mass index (BMI) was favourable, but the prevalence of heavy alcohol drinkers was high. Comparing the first to the second study reveals a decrease in sodium excretion in Toyama, although that area still had the highest value of the three study centres. The average potassium excretion increased only in Osaka. Sodium/potassium ratio decreased in all centres. BMI and the prevalence of heavy drinkers among the subjects of both studies were nearly the same. The trend of the relationship of sodium to BP in Osaka changed from negative to positive. In Toyama, it changed from positive to negative. It is thought that this negative relationship might occur in conjunction with a reduction in salt consumption in a population. In conclusion this study reveals that average sodium consumption in Japan remains high while potassium consumption is still low. As a factor in the prevention of hypertension, further efforts to reduce salt consumption and increase potassium intake are still needed.

Adult↗

PubMed1999

Extrathymic derivation of gut lymphocytes in parabiotic mice.

In adult mice, c-kit+ stem cells have recently been found in their liver, intestine and appendix, where extrathymic T cells are generated. A major population of such thymus-independent subsets among intraepithelial lymphocytes is T-cell receptor (TCR)gamma delta+ CD4- CD8alpha alpha+(beta-) cells, but the origins of other lymphocyte subsets are still controversial. In this study, we examined what type of lymphocyte subsets were produced in situ by such stem cells in the small intestine, large intestine and appendix. To investigate this subject, we used parabiotic B6.Ly5.1 and B5.Ly5. 2 mice which shared the same circulation by day 3. The origin of lymphocytes was identified by anti-Ly5.1 and anti-Ly5.2 monoclonal antibodies in conjunction with immunofluorescence tests. Lymphocytes in Peyer's patches and lamina propria lymphocytes (especially B cells and CD4+ T cells) in the small intestine became a half-and-half mixture of Ly5.1+ and Ly5.2+ cells in each individual of parabiotic pairs of mice by day 14. However, the mixture was low in CD8alpha alpha+, CD8alpha beta+ and gamma delta T cells in the small and large intestines and in CD3+ CD8+ B220+ cells in the appendix. These cells might be of the in situ origin. When one individual of a pair was irradiated before parabiosis, the mixture of partner cells was accelerated. However, a low-mixture group always continued to show a lower mixture pattern than did a high-mixture group. The present results suggest that extrathymic T cells in the digestive tract may arise from their own pre-existing precursor cells and remain longer at the corresponding sites.

Animals↗

PubMed1999

Isolation and characterization of Neurospora crassa nucleoside diphosphate kinase NDK-1.

We have previously reported that phosphorylation of a 15-kDa protein increased after blue-light irradiation in Neurospora crassa. In this study, the 15-kDa protein was purified using four columns; DEAE-cellulose, Blue-Sepharose, SP-Sepharose and Mono Q. The 15-kDa protein was shown to be homologous with nucleoside diphosphate kinase by amino acid sequencing and was also shown to possess nucleoside diphosphate kinase activity. A gene encoding N. crassa nucleoside diphosphate kinase, ndk-1, was isolated from the mycelial cDNA and genomic libraries. The deduced amino acid sequence of NDK-1 was identical to that of the 15-kDa protein. Northern blot analysis suggested that WC-1 and WC-2, the key factors of blue-light signal transduction in N. crassa, did not regulate NDK-1 at the transcriptional level. NDK-1 also showed rapid autophosphorylation activity and protein kinase activity against myelin basic protein with a Km value of 0.36 mM. These results suggest that NDK-1 acts as a signal transducer by phosphorylating proteins.

Amino Acid Sequence↗

PubMed1999

Two cases of HLA-DR2-negative hypersomnia manifesting sleep-onset rapid eye movement periods in the multiple sleep latency test.

We encountered two cases expressing excessive daytime sleepiness (EDS) and manifesting two or more sleep-onset rapid eye movement (REM) periods in the multiple sleep latency test. Unbearable daytime sleepiness occurred abruptly, which usually led to short-lasting naps, after which the patients felt refreshed. The EDS was successfully reduced by treatment with methylphenidate. In spite of these features similar to narcolepsy, these cases of REM hypersomnia did not present cataplexy or other auxiliary symptoms of narcolepsy, and, furthermore, the class-II human leukocyte antigen DR2 appeared to be negative.

Adult↗

PubMed1999

Syndrome of inappropriate secretion of antidiuretic hormone associated with amyotrophic lateral sclerosis in respiratory failure.

A 65-year-old man who had muscle weakness and dysarthria was admitted for investigation of motor neuron disease. He had lost 12 kg of weight in 6 months. Neurological findings disclosed upper and lower motor neuron disturbances with normal sensory nerve function, and needle electromyography showed a neurogenic pattern. Laboratory findings on admission demonstrated dilutional hyponatraemia due to an excessive secretion of antidiuretic hormone (ADH). Based on these findings, the patient was diagnosed as having the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with amyotrophic lateral sclerosis (ALS). During the night of first hospital day, the patient complained of severe dyspnoea, and mechanical ventilation was commenced. Following the mechanical ventilation, plasma ADH levels and serum sodium concentration were normalized. We propose that respiratory failure secondary to the atrophy of respiratory muscle might be responsible for the development of SIADH.

Aged↗