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Biomedical subjects

Y Tamada

Publications and source records attributed to Y Tamada.

At least 37 records · Page 2Linked to original sources
PubMed2000

Preparation and characterization of apatite deposited on silk fabric using an alternate soaking process.

Apatite-deposited silk fabric composite materials were developed using a new alternate soaking process. The characteristics of deposited apatite were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), and X-ray photoelectron spectroscopy (XPS). Apatite weight increased with alternating soaking in a calcium solution [200 mM aqueous calcium chloride solution buffered with tris(hydroxymethyl) aminomethane and HCl (pH 7.4)] and a phosphate solution (120 mM aqueous disodium hydrogenphosphate) changed every hour. SEM showed that apatite deposited after 21 or more repeated soakings was over 20 microm thick. XRD showed that with alternate soakings, the apatite crystals deposited on silk fabric elongated along the c axis. FTIR and XPS indicated the existence of carbonate, HPO(4)(2-), and Na(+) ions in addition to constituent ions of hydroxyapatite. A loss of HPO(4)(2-) and Na(+) ions in the deposit upon further soaking might be associated with an increasing apatite crystallinity. Apatite deposited on silk by the alternate soaking process was a deficient apatite containing carbonate, HPO(4)(2-), and Na(+) ions as in a natural bone tissue. Thus, this apatite-silk composite material might be potentially bioactive.

Animals↗
PubMed2000

Development of astroglial elements in the suprachiasmatic nucleus of the rat: with special reference to the involvement of the optic nerve.

The development of astroglial cells and the effect of the retinohypothalamic tract on it were studied by vimentin and glial fibrillary acidic protein (GFAP) immunocytochemistry in the suprachiasmatic nucleus (SCN) of the rat. At the embryonic stage, vimentin-immunoreactive (VIM-IR) radial glia, precursors of astrocytes, were dominant. However, their filaments vanished in the first few postnatal days. Instead of VIM-IR glial filaments, GFAP-immunoreactive (GFAP-IR) astrocytes appeared at E20 and grew rapidly from the P3 stage. GFAP immunoreactivity in the ventrolateral portion of the SCN (VLSCN) was measured using a computer-assisted image analyzing system. In normal rats, GFAP immunoreactivity showed a stepwise pattern with two slopes at P3-P4 and P20-P25. Bilaterally eye-enucleated rats operated on the day of birth showed lower GFAP immunoreactivity than normal rats and the GFAP immunoreactivity did not increase between P20 and P25 when GFAP-IR glial processes rapidly expand. Electron microscopic investigation at P50 (adult stage) revealed that neurons in the VLSCN had often direct apposition without astroglial processes and the frequency of this finding was significantly higher in eye-enucleated rats than in the control rats. These findings strongly suggest that the postnatal development of astroglial elements, particularly the expansion of GFAP-IR processes in the SCN, is regulated by retinohypothalamic projection.

Afferent Pathways↗
PubMed2000

Chemical modification of silk fibroin with 2-methacryloyloxyethyl phosphorylcholine. II. Graft-polymerization onto fabric through 2-methacryloyloxyethyl isocyanate and interaction between fabric and platelets.

2-Methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto silk fabric in a two-step heterogeneous system through the vinyl bonds of 2-methacryloyloxyethyl isocyanate (MOI) modified on the fabric. First, habutae silk fabric was modified with the MOI monomer in anhydrous dimethyl sulfoxide using di-n-butyltin (IV) dilaurate and hydroquinone at 35 degrees C. The saturated weight gain of modified MOI monomer on the fabric was 7.3 wt% versus the original silk. Second, graft polymerization with MPC onto the MOI modified silk was conducted using 2,2'-azo bis[2-(2-imidazolin-2-yl)propane dihydrochloride] (VA-044) as an azo polymerization initiator. The weight of the grafted MPC eventually gained was about 26.0 wt%. The MOI-modified and MPC-grafted silk fabrics were analyzed by Fourier transform infrared (FT-IR) spectroscopy. To confirm the improved biocompatibility of the silk fabric, platelet adhesion was preliminarily tested measuring lactate dehydrogenase. The number of platelets adhering to polyMPC-grafted silk fabric decreased by about one tenth compared to original and MOI-modified silk after 60 min of contact with human platelet-rich plasma (1.0 x 10(6) platelets cm(-2)).

Animals↗
PubMed2000

Involvement of cysteine proteases in bFGF-induced angiogenesis in guinea pig and rat cornea.

Overexpression and activation of matrix metalloprotease (MMP) have been implicated in angiogenesis. However, the involvement of cysteine proteases, such as calpains (EC 34.22.17), is obscure. Thus, the purpose of this experiment was to study the involvement of cysteine proteases in angiogenesis induced by basic fibroblast growth factor (bFGF) in guinea pig and rat corneas using cysteine protease inhibitors. Sustained-release polymers containing bFGF were implanted into guinea pig and rat corneas to induce angiogenesis. For treatment of corneal angiogenesis, polymers containing cysteine protease inhibitors, leupeptin or SJA6017, were also implanted into corneas. Using the slit lamp, the corneas were observed for nine days after polymer implantation. Soluble proteins and albumin levels were used as markers of corneal injury by angiogenesis. bFGF induced angiogenesis in guinea pig and rat corneas. In guinea pig cornea, wet weight, the amount of soluble protein and albumin was highest at four days after bFGF-containing pellet implantation. In rat cornea, the amount of soluble protein and albumin was highest at six days, and wet weight increased within four days. One hundred nmole of leupeptin showed a tendency to reduce bFGF-induced angiogenesis in guinea pig cornea, and 10 nmole of SJA6017 was effective in reducing bFGF-induced angiogenesis in rat cornea, although SJA6017 showed a stronger effect than leupeptin. Ten nmole of SJA6017 significantly reduced the number of new blood vessels. These data suggested involvement of cysteine proteases in angiogenesis in guinea pig and rat cornea.

Albumins↗
PubMed2000

Sulfated fibroin, a novel sulfated peptide derived from silk, inhibits human immunodeficiency virus replication in vitro.

We prepared two kinds of sulfated silk fibroins, SclFib30 and SclFib31, which contain different amounts of sulfate. These sulfated silk fibroins have anti-HIV-1 activity in vitro, apparently due to interference with the adsorption of virus particles to CD4+ cells, and completely blocked virus binding to the cells at a concentration of 100 microg/ml. Sulfated fibroins also abolished cell-to-cell infection-induced syncytium formation upon cocultivation of MOLT-4 and MOLT-4/HIV-IIIB cells, suggesting that they would interfere with gp120 and prevent the formation of gp120/CD4 complex. Silk is used in biomaterials such as surgical sutures and is believed to be a safe material for humans. In accordance with low anticoagulant activity and high anti-HIV-1 activity against both X4 HIV-1 and R5 HIV-1 strains, sulfated silk fibroins have potential as antiviral material such for a vaginal anti-HIV formulation.

Animals↗
PubMed1999

p48 (ISGF-3gamma) is involved in interferon-alpha-induced suppression of hepatitis B virus enhancer-1 activity.

Interferon-alpha (IFN-alpha) suppresses hepatitis B virus (HBV) gene expression by reducing its enhancer-1 activity. IFN-alpha induces transcription factors, interferon-stimulated gene factor 3 (ISGF3), and interferon regulatory factor-1 (IRF-1), which activate interferon-inducible gene expression through binding to the interferon-stimulated regulatory element (ISRE) "AGTTTCNNTTTCNC" in the gene promoters. We found the ISRE-like sequence "AGGCTTTCACTTTCTC" in the HBV enhancer-1 region and elucidated the role of this sequence. Gel mobility shift assay showed binding of in vitro translated IRF-1 and in vitro translated p48 (ISGF3-gamma), which is a component of ISGF3 to this sequence. However, nuclear extracts binding to this sequence from human hepatoma cells (HuH-7) treated with IFN-alpha contained only the protein consisted of p48. In transfection experiments, IFN-alpha suppressed the HBV enhancer-1 activity, and overexpression of p48 enhanced this inhibitory effect. Both mutation and deletion of the ISRE-like sequence in the HBV enhancer-1 region reduced the suppressive effect of IFN-alpha. Our results suggest that the ISRE-like sequence in the HBV enhancer-1 can interact with the protein containing p48 and mediate the IFN-alpha-induced suppression of the enhancer activity.

Base Sequence↗
PubMed1999

Expanded expression of heme oxygenase-1 (HO-1) in the hypothalamic median eminence of aged as compared with young rats: an immunocytochemical study.

This study was performed to examine the differences in expression of heme oxygenase protein with age using immunocytochemistry. We compared the contents of HO-1 and HO-2 between young and aged rats using immunocytochemical methods. Stronger HO-1 expression was detected in the internal layer of the median eminence (ME) of aged than of young rats. Moreover, the cells expressing HO-1 were larger in the aged than the young animals. Electron microscopy indicated these cells with HO-1-like immunoreactivity (HO-1-LI) to be astrocytes. These findings suggested that the expression of HO-1 increased in the ME with age. The significance of this increased expression of HO-1 with age will be discussed briefly.

Aging↗
PubMed1999

Cytochemical study of prolactin-releasing peptide (PrRP) in the rat brain.

Strong positive signals for PrRP mRNA and PrRP-like immunoreactivity (PrRP-LI) were detected in the nucleus of the solitary tract and ventral and lateral reticular formation of the caudal medulla oblongata. Weak mRNA signals and immunoreactivity were seen scattered from the hypothalamic dorsomedial nucleus (DMH) to ventromedial nucleus (VMH). Nerve processes and terminals with PrRP-LI were detected from the septal region to the diencephalon. These nerve processes were also clearly visible around capillary walls and in the vicinity of the ependymal cells of the third and lateral ventricles. These observations suggested that PrRP might be secreted into the systemic circulation and cerebrospinal fluid and may play functional roles other than in the release of prolactin from the anterior pituitary.

Animals↗
PubMed1999

Functional morphology of the suprachiasmatic nucleus.

In mammals, the biological clock (circadian oscillator) is situated in the suprachiasmatic nucleus (SCN), a small bilaterally paired structure just above the optic chiasm. Circadian rhythms of sleep-wakefulness and hormone release disappear when the SCN is destroyed, and transplantation of fetal or neonatal SCN into an arrhythmic host restores rhythmicity. There are several kinds of peptide-synthesizing neurons in the SCN, with vasoactive intestinal peptide, arginine vasopressin, and somatostatine neurons being most prominent. Those peptides and their mRNA show diurnal rhythmicity and may or may not be affected by light stimuli. Major neuronal inputs from retinal ganglion cells as well as other inputs such as those from the lateral geniculate nucleus and raphe nucleus are very important for entrainment and shift of circadian rhythms. In this review, we describe morphological and functional interactions between neurons and glial elements and their development. We also consider the expression of immediate-early genes in the SCN after light stimulation during subjective night and their role in the mechanism of signal transduction. The reciprocal interaction between the SCN and melatonin, which is synthesized in the pineal body under the influence of polysynaptic inputs from the SCN, is also considered. Finally, morphological and functional characteristics of clock genes, particularly mPers, which are considered to promote circadian rhythm, are reviewed.

Animals↗
PubMed1999

The influence of salt loading on vasopressin gene expression in magno- and parvocellular hypothalamic neurons: an immunocytochemical and in situ hybridization analysis.

Arginine vasopressin peptide and messenger RNA expression were examined at the cellular level in the magnocellular and parvocellular neurons in the rat paraventricular nucleus after dehydration and rehydration, employing immunocytochemistry and in situ hybridization histochemistry on the same tissue sections. Most magnocellular vasopressinergic neurons of control animals expressed both vasopressin-like immunoreactivity and messenger RNA. However, neurons negative for vasopressin-like immunoreactivity but expressing messenger RNA were also detected, and their number increased during dehydration. In contrast, almost all of the parvocellular vasopressinergic neurons of dehydrated animals expressed vasopressin messenger RNA alone, with continued increase in their number after rehydration, despite return of the number of magnocellular vasopressinergic neurons to the control level. Vasopressin messenger RNA and corticotropin releasing factor-like immunoreactivity were co-localized in the same parvocellular neurons, and vasopressin-immunoreactive nerve terminals were detected in the external zone of the median eminence. These findings suggest that magno- and parvocellular vasopressinergic neurons are differentially activated during dehydration/rehydration. Osmotic stimuli activate all magnocellular vasopressinergic neurons, but the effect is not simultaneous in all of these neurons. Parvocellular vasopressinergic neurons are also activated by the stress of dehydration which effect appears to last longer than in the magnocellular system.

Animals↗
PubMed1999

Different serum soluble Fas levels in patients with allergic rhinitis and bronchial asthma.

BACKGROUND: The pathogeneses of allergic rhinitis and bronchial asthma are believed to be closely mutually related because of the similar dynamics of allergy-inducing cells and molecules and clinical overlap. In this study, we compared these diseases in the dynamics of cell apoptosis-regulating molecules. METHODS: Allergic rhinitis patients (n=36), bronchial asthma patients (n=22), and healthy subjects (n=32) were subjected to measurement of serum (soluble Fas) (sFas) levels during the stable and attack disease phases by a sandwich enzyme-linked immunosorbent assay. RESULTS: Serum sFas levels in patients with allergic rhinitis during the attack phase were significantly lower (P<0.0001) than those in healthy individuals. There were no differences between them during the attack and stable disease phases. In contrast, serum sFas levels in patients with bronchial asthma during the attack phase were higher (P<0.0005) than those in healthy individuals. Interestingly, the levels during the attack phase were lower (P<0.002) than those during the stable phase. CONCLUSIONS: Our results suggest a different pathogenesis for allergic rhinitis and bronchial asthma at the cell apoptosis-linked step.

Apoptosis↗
PubMed1999

NGFI-A gene expression induced in the rat suprachiasmatic nucleus by photic stimulation: spread into hypothalamic periventricular somatostatin neurons and GABA receptor involvement.

We studied NGFI-A gene expression in response to photic stimulation in the rat suprachiasmatic nucleus (SCN) using in situ hybridization histochemistry. This gene expression spread within the SCN and extended dorsally into the anterior hypothalamus after 30 min-1 h of light exposure at circadian time (CT) CT18. It appeared first in the ventrolateral SCN where the retinohypothalamic tract (RHT) innervates, then it expanded dorsomedially in the SCN and beyond the SCN to the anterior hypothalamus. However, stimulation for 2 h light exposure decreased its expression in the SCN. NGFI-A expression in the somatostatin neurons in the periventricular nucleus increased from 8.7% to 41% with increasing exposure time from 5 to 30 min. NGFI-A mRNA expression in the SCN was suppressed by pretreatment with baclofen, the GABAB receptor agonist. The spread of photic information from the retina to the SCN was visualized at immediate early gene level not only in the SCN but also in the area beyond the SCN. Somatostatin neurons in the periventricular nucleus which project to the external layer of the median eminence and are involved in regulation of growth hormone release showed NGFI-A gene expression corresponding to the duration of photic stimulation. Photic-induced NGFI-A gene expression in the SCN was also shown to be regulated by GABAergic transmission via GABAB receptors. These NGFI-A gene-expressing cells in the SCN may be involved in the circadian entrainment by light and some of those outside the SCN may participate in the regulation of neuroendocrine function.

Animals↗
PubMed1999

Soluble E-selectin as a marker of disease activity in pustulosis palmaris et plantaris.

In this study, we investigated a possible correlation between adhesion molecules and activity of pustulosis palmaris et plantaris (PPP). Serum levels of soluble E-selectin (sE-selectin), soluble intercellular adhesion molecules 1 (sICAM-1) and tumour necrosis factor alpha (TNF-alpha) in 30 untreated PPP patients were examined, and compared with those in 20 healthy subjects. Values in 10 PPP patients were re-examined after treatment. Serum levels of sE-selectin and TNF-alpha in untreated PPP patients were significantly higher than those in healthy subjects. There was a statistically significant correlation between the disease activity and serum levels of sE-selectin in untreated PPP patients. Furthermore, disease activity of PPP was higher in patients who smoked and during the summer, with elevation of serum sE-selectin levels. Serum levels of sE-selectin were downregulated with the recovery from PPP. These results suggest that sE-selectin may play a role in the pathogenesis of PPP and could be a reliable marker of its disease activity.

Adult↗
PubMed1999

Ca-adsorption and apatite deposition on silk fabrics modified with phosphate polymer chains.

Silk fabric was modified with polymethacryloyloxyethylphosphate (pMOEP) by graft copolymerization. Ca-adsorption onto pMOEP-grafted silk fabric was significantly enhanced compared to that onto original silk fabric. SEM observation indicated that some crystallites were deposited on the pMOEP-grafted silk fabric after 1 week of immersion in simulated body fluid, whereas no change occurred on the surface of the original silk fabric. X-ray diffraction showed that this crystallite contained hydroxyapatite. These results indicate that pMOEP-grafted silk fabric induce hydroxyapatite formation more effectively than the original silk fabric.

Adsorption↗
PubMed1999

Carbohydrate epitopes and mucins expressed by 17 human ovarian carcinoma cell lines.

Ovarian carcinomas are known to be diverse in their histological types and response to therapeutic agents. Specific immunotherapy by the use of mucins or carbohydrate vaccines has been attempted, in which expression of these epitopes by each histotype should clearly be assessed. Seventeen human ovarian carcinoma cell lines were evaluated for their expression of mucin core polypeptide mRNAs (MUC1, MUC2, MUC3, MUC5AC, MUC5B, and MUC6) by the reverse transcription-polymerase chain reaction. They were also examined for their expression of mucin-associated carbohydrate epitopes by flow cytometry. Eleven monoclonal antibodies, including those specific for Lewis antigen-related epitopes and Tn-related epitopes, were used. Expression of the MUC1 gene and sialyl Lewis X was characteristic to all five cell lines derived from clear cell adenocarcinomas. Multiple mucin genes and a diverse range of carbohydrate epitopes were observed with all six cell lines derived from mucinous adenocarcinomas. Mucin-associated carbohydrate epitopes were not detected on three of four serous adenocarcinoma cell lines, although MUC1 and MUC2 mRNAs were detected in all of them. Therefore, ovarian carcinoma cells from tumors of different histological types showed characteristic expression patterns of mucin genes and carbohydrate epitopes.

Adenocarcinoma, Clear Cell↗
PubMed1998

Neuron-glia interaction in the suprachiasmatic nucleus: a double labeling light and electron microscopic immunocytochemical study in the rat.

The morphological interactions between astroglial and neuronal elements were elucidated in the rat suprachiasmatic nucleus (SCN) by light and electron microscopic immunocytochemistry using antibodies against glial fibrillary acidic protein (GFAP), vasoactive intestinal peptide (VIP) and arginine-vasopressin (AVP). Throughout the SCN, particularly in its ventral portion, GFAP-like-immunoreactive (GFAP-LI) astroglial elements were found. These astrocytes displaying GFAP-like immunoreactivity occasionally contained fairly well-developed organelles. Some of these astrocytes were found as satellite cells in close contact with non-immunoreactive neuronal perikarya and processes. Around the neurons, GFAP-LI astroglial processes were also observed to cover some portions of presynaptic and postsynaptic elements. In addition, these astroglial elements were seen between two neuronal somata and pericytes of blood capillaries as glial endfeet. By double labeling immunoelectron microscopy using antibodies against GFAP/VIP and GFAP/AVP, some portions of VIP-like-immunoreactive or AVP-like-immunoreactive neuronal somata and processes were found to be engulfed by GFAP-LI astroglial processes. The possible functional roles of the morphological interactions between astroglial and neuronal elements are discussed.

Animals↗