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Biomedical subjects

H Hirata

Publications and source records attributed to H Hirata.

At least 37 records · Page 2Linked to original sources
PubMed2001

A new method for removal of albumin-binding uremic toxins: efficacy of an albumin-dialysate.

It is difficult for conventional hemodialysis to remove albumin-binding uremic toxins (ABUTs) even though they are low molecular weight substances. We investigated the efficiency of albumin-dialysate (AD) for removal of ABUT. Phenols and indoxyl sulfate were selected as ABUT. In vitro dialysis was performed for 2 h in the closed circuit with ABUT containing plasma as a test solution using conventional dialysate (CD) or AD. By the use of CD, the ABUT concentration in the test solution only was reduced by 20 to 30%. On the other hand, AD caused a marked reduction and an increase in test solution and dialysate concentration of ABUT, respectively. ABUT in AD could be adsorbed effectively by activated-charcoal column; accordingly, the ABUT concentration in the test solution continued to decrease throughout the study period. These results suggest that AD could remove ABUT more efficiently than CD, and AD may be useful for reducing accumulated ABUT levels.

Dialysis Solutions↗
PubMed2001

Intensity coding by TMJ-responsive neurons in superficial laminae of caudal medullary dorsal horn of the rat.

Temporomandibular disorders (TMD) represent a family of recurrent conditions that often cause pain in the temporomandibular joint (TMJ) region and muscles of mastication. To determine if TMJ-responsive neurons encoded the intensity of pro-inflammatory chemical signals, dose-effect relationships were assessed after direct injection bradykinin into the joint space and compared with responses after injection of glutamate or saline. Neurons were recorded from superficial laminae of the trigeminal subnucleus caudalis/upper cervical cord junction region (Vc/C(2)) and identified by palpation of the TMJ region in barbiturate-anesthetized male rats. The majority (62 of 84) of units received convergent input from facial skin, while 26% were driven only by deep input from the TMJ region. Conduction-velocity based on the latency to firing after electrical stimulation of the TMJ region indicated 64% of units were driven by A-delta fiber input only. Bradykinin (0.1-10 microM) excited 69% of neurons tested, and 70% (19 of 27) of these units were activated by the lowest dose (0.1 microM). Glutamate (50-200 mM) excited 27% of units; however, when tested after bradykinin, 58% of units were activated by glutamate. Some TMJ units (17%) were excited by saline injection alone and not enhanced further by bradykinin or glutamate. Most (88%) TMJ units were activated by injection of the small fiber excitant, mustard oil (20% solution), into the TMJ region. Units responsive to bradykinin or glutamate were not restricted to particular classes [e.g., wide dynamic range (WDR), nociceptive specific (NS), deep only]. A small percentage of TMJ units (approximately 15%) were activated antidromically from the contralateral posterior thalamus. In parallel studies using c-fos immunocytochemistry, bradykinin (1 microM) injection into the TMJ region produced a greater number of Fos-positive neurons at the Vc/C(2) region than glutamate (200 mM) or saline. These results revealed two broad classes of TMJ units that encoded the intensity of pro-inflammatory chemical stimuli applied to the TMJ region, units that received convergent nociceptive input from facial skin (i.e., WDR and NS units) and units that responded only to deep input from the TMJ region. On the basis of encoding properties and efferent projection status, it is concluded that activation of TMJ units within the superficial laminae at the Vc/C(2) region contribute to the diffuse and spreading nature of TMD pain sensation.

Animals↗
PubMed2001

[Crystalline molecular complexes generated between surfactants and various additive compounds: an attempt to modify sparingly water soluble drugs to easily water soluble drugs].

It has been established that ionic surfactants, whether cationic or anionic, provide crystalline molecular complexes stably with various aromatic compounds as additives. Among various additives phenolic compounds are especially favorable for both surfactant species. Other than these additives, cationic surfactants easily provide crystalline molecular complexes with basic materials and even with non-polar substances such as biphenyl and phenanthrene. The isolated surfactant molecular complexes were analyzed by X-ray. To date the number of the obtained surfactant molecular complexes exceeds two hundred species or more and thirty or more of them were structurally analyzed. These surfactant molecular complexes were shown to be novel surfactant species different from their mother species, supplied with enhanced solubility to the complex additives. We applied these characteristics to sparingly water soluble drugs as the complex additive to modify them into easily water soluble drugs. The obtained complex drugs revealed an improved behavior in solubility and dissolution rate compared with pure drugs.

Crystallization↗
PubMed2000

Cycloprodigiosin hydrochloride, H(+)/CL(-) symporter, induces apoptosis and differentiation in HL-60 cells.

Cycloprodigiosin hydrochloride (cPrG * HCl), a novel H(+)/Cl(-) symporter, induces acidification of the cytosol and leads to apoptosis in rat and human liver cancer cells. In the present study, the effect of cPrG * HCl on a promyelocytic leukemia cell line (HL-60) was examined. cPrG * HCl lowered intracellular pH and induced apoptosis through up-regulation of Fas ligand, activation of stress-activated protein kinase (SAPK/JNK) and caspase. Apoptosis induced by cPrG * HCl was strongly suppressed when a cell-permeable weak base, imidazole, was present, indicating that cytosol acidification introduced by cPrG * HCl triggered caspase activation, leading to apoptosis. Concomitantly, cell differentiation into monocyte was also induced by cPrG * HCl both morphologically and functionally. However, the cPrG * HCl-induced differentiation was not suppressed by addition of imidazole, indicating that the differentiation process is unrelated to cytosol acidification. Further, the differentiation induced by cPrG * HCl was blocked by tyrosine kinase inhibitors (lavendustin A and HMA) but unaffected by the inhibitors of A-kinase (H-89) or C-kinase (H-7). Taken together, these findings suggest that cPrG * HCl, through apoptosis and differentiation induction, may be useful in leukemia treatment.

Antiporters↗
PubMed2000

Light and Oxygen Protective Properties of Materials Induced by Surfactant Molecular Complex Formation.

Crystalline surfactant molecular complexes, the quite stable existence of which we firmly established through X-ray structural analysis, etc., were examined with respect to the protection from UV light and oxygen provided to their additive components. Structural analysis has revealed that the complex additives are stably occluded in the mother surfactant crystal matrix. Through the examination it was confirmed that additive components in a cationic complex crystal structure were perfectly protected from both UV light and oxygen. On the other hand, in anionics the additives were perfectly safe from UV attack, but from oxygen the change was rather accelerated in comparison with the effect of that on the pure condition. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Generation of structurally and functionally distinct factors from the basic helix-loop-helix gene Hes3 by alternative first exons.

The basic helix-loop-helix gene Hes3 is expressed by differentiating and mature Purkinje cells in the cerebellum and by neural precursor cells in the embryonal nervous system. We here found that the transcript of cerebellar Hes3, designated Hes3a, has a distinct 5'-terminal structure from that of embryonal Hes3, designated Hes3b, and that the two types of Hes3 transcripts are generated from different first exons. Hes3a lacks the amino-terminal half of the basic region and thus does not bind to the DNA, whereas Hes3b contains a complete basic region and binds to the N box sequence with a high affinity like Hes1, another member of the Hes family. Both types of Hes3 proteins functionally antagonize the neuronal determination factor Mash1, but only Hes3b represses transcription from the N box-containing promoter like Hes1. Furthermore, misexpression of Hes3b with retrovirus in neural precursor cells inhibits neuronal differentiation like Hes1, whereas Hes3a does not. Thus, alternative promoters and first exons that are differentially utilized during neural development generate structurally and functionally distinct proteins from a single Hes3 gene locus.

Alternative Splicing↗
PubMed2000

N-acetylcysteine suppresses TNF-induced NF-kappaB activation through inhibition of IkappaB kinases.

Here, we used a reductant, N-acetyl-L-cysteine (NAC), to investigate the redox-sensitive step(s) in the signalling pathway from the tumor necrosis factor (TNF) receptor to nuclear factor kappaB (NF-kappaB). We found that NAC suppressed NF-kappaB activation triggered by TNF or by overexpression of either the TNF receptor-associated death domain protein, TNF receptor-associated factor 2, NF-kappaB-inducing kinase (NIK), or IkappaB kinases (IKKalpha and IKKbeta). NAC also suppressed the TNF-induced activation of IKKalpha and IKKbeta, phosphorylation and degradation of IkappaB, and nuclear translocation of NF-kappaB. Furthermore, NAC suppressed the activation of IKKalpha and IKKbeta triggered by the overexpression of NIK. These results indicate that IKKalpha and IKKbeta are subject to redox regulation in the cells, and that NAC inhibits NF-kappaB activation through the suppression of these kinases.

Acetylcysteine↗
PubMed2000

Repair of nerve gap with the elongation of Wallerian degenerated nerve by tissue expansion.

We have found previously that expansion of the Wallerian degenerated nerve was accompanied by accelerated Schwann cell proliferation. In this study, we investigated the usefulness of the elongation of Wallerian degenerated nerve for the repair of short nerve gap. Male Wistar rats were used. After the left sciatic nerve was transected the rats were divided into 4 groups. In the control group, nerve coaptation was not performed. In group 1, tensionless coaptation was performed immediately. In group 2, delayed tensionless coaptation was performed with the elongation of Wallerian degenerated nerve. In group 3, coaptation was performed immediately with autologous interposition nerve graft. The ideal tensionless nerve repair of group 1 was considered to produce the best result. Rats in group 2 showed functional recovery as good as rats in group 1. On histologic assessment, in group 2, a fibrous capsule that was very rich in vascularity was formed around the tissue expander. After 14 weeks, the capsule was diminished markedly in size, but the vascularity was rich around the sciatic nerve. We think that the excellent functional recovery seen in group 2 can be attributed to the increased activity of Schwann cell proliferation and increased vascularity.

Animals↗
PubMed2000

Electronically tunable surface-coil-type resonator for L-band EPR spectroscopy.

The automatic frequency control (AFC) circuit in conventional electron paramagnetic resonance (EPR) spectrometers automatically tunes the microwave source to the resonance frequency of the resonator. The circuit works satisfactorily for samples stable enough that the geometric relations in the resonance structure do not change in a significant way. When EPR signals are measured during in vivo experiments with small rodents, however, the distance between the signal source and the surface-coil detector can change rapidly. When a conventional AFC circuit keeps the oscillator tuned to the resonator under those conditions, the resultant frequency change may exceed +/-5 MHz and markedly shift the position of the EPR signal. Such a shift results in unacceptable effects on the spectra, especially when the experimenter is dealing with narrow EPR lines. The animal movement also causes a mismatching of the resonator and the 50-ohm transmission line. Direct results of this mismatching are increased noise; shifts in the position of the baseline; and a high probability of overdriving the signal preamplifier with consequent loss of the EPR signal. We therefore designed, built, and tested a new surface-coil resonator using varactor diodes for tuning the resonance frequency to the fixed frequency oscillator and for capacitive matching of the resonator to the 50-ohm transmission line. The performance of the automatic matching system was tested in vivo by measuring EPR spectra of lithium phthalocyanine implanted in rats. Stability and sensitivity of the spectrometer were evaluated by measuring EPR spectra with and without the use of the automatic matching system. The overall experimental performance of the spectrometer was found to significantly improve during in vivo experiments using the automatic matching system. Excellent matching between the 50-ohm transmission line and the resonator was maintained under all experimental circumstances that were tested. This should allow us now to carry out experiments that previously were not possible.

Animals↗
PubMed2000

Cycloprodigiosin hydrochloride, a H+/Cl- symporter, induces apoptosis in human breast cancer cell lines.

The effect of cycloprodigiosin hydrochloride (cPrG.HCl), a H+/Cl- symporter, on five human breast cancer cell lines (KPL-1, T-47D, MCF-7, MKL-F, and MDA-MB-231), a human breast epithelial cell line (HBL-100), and a human fibroblast cell line (WI-38-40) was examined. cPrG.HCl inhibited the growth of all five breast cancer cell lines (IC50: 0.46-0.62 microM) and slightly inhibited HBL-100 and WI-38-40 cell growth (IC50: 1.75 microM and 2.26 microM respectively). cPrG.HCl treatment in KPL-1 cells increased the pH of acidic organelles, decreased intracellular pH, and caused apoptosis, which was confirmed by the appearance of a sub-G1 population by flow cytometry and DNA fragmentation. In addition, cPrG.HCl-induced apoptosis was strongly suppressed by imidazole, a cell-permeable base, suggesting that intracellular acidification was essential for the apoptosis. Further, cPrG.HCl treatment up-regulated Bax and Bak expression, down-regulated Bcl-2 expression, and activated caspase-3. Therefore, the intracellular acidification by cPrG.HCl treatment suppressed the growth of human breast cancer cell lines by inducing apoptosis.

Antiporters↗
PubMed2000

Induction of apoptosis of activated murine splenic T cells by cycloprodigiosin hydrochloride, a novel immunosuppressant.

Two types of immunosuppressants, cycloprodigiosin hydrochloride (cPrG) and L-leucyl-L-leucine methyl ester (LeuLeuOMe), both have the ability to selectively inhibit the lysosomal function, and a related compound to cPrG, prodigiosin 25-C, and LeuLeuOMe have been reported to selectively inhibit the T cell function in vitro. We therefore examined the cell-type specificity of cPrG and LeuLeuOMe using murine splenocytes. Concanavalin A (Con A)- and lentil lectin-induced proliferation was suppressed by cPrG more profoundly than lipopolysaccharide-induced proliferation. At the optimal concentration, Con A induced the proliferation of both CD4+ and CD8+ cells, whereas at a supra-optimal concentration Con A induced rather selective proliferation of CD8+ cells. Irrespective of the dose of Con A, CD4+ and CD8+ cells were equally affected by cPrG. In contrast, LeuLeuOMe induced the selective loss of CD8+ cells. cPrG enhanced the apoptosis of murine splenocytes and nylon fiber column-purified T cells cultured in the presence of Con A, as shown by the decrease in cell size and/or DNA fragmentation. Overall, this study revealed that the cell-type specificity of cPrG is different from that of LeuLeuOMe, and that the immunosuppression by cPrG is associated with apoptosis.

Animals↗
PubMed2000

Identification of CD72 as a lymphocyte receptor for the class IV semaphorin CD100: a novel mechanism for regulating B cell signaling.

We have identified the lymphocyte semaphorin CD100/Sema4D as a CD40-inducible molecule by subtractive cDNA cloning. CD100 stimulation significantly enhanced the effects of CD40 on B cell responses. Administration of soluble CD100 markedly accelerated in vivo antigen-specific antibody responses. CD100 receptors with different binding affinities were detected on renal tubular cells (K(d) = approximately 1 x 10(-9)M) and lymphocytes (K(d) = approximately 3 x 10(-7)M). Expression cloning revealed that the CD100 receptor on lymphocytes is CD72, a negative regulator of B cell responsiveness. CD72 thus represents a novel class of semaphorin receptors. CD100 stimulation induced tyrosine dephosphorylation of CD72 and dissociation of SHP-1 from CD72. Our findings indicate that CD100 plays a critical role in immune responses by the novel mechanism of turning off negative signaling by CD72.

Animals↗
PubMed2000

Epidermal growth factor receptor is modulated by redox through multiple mechanisms. Effects of reductants and H2O2.

The cellular redox state has been shown to play an essential role in cellular signaling systems. Here we investigate the effects of reductants and H2O2 on the signaling of epidermal growth factor (EGF) in cells. H2O2 induced the phosphorylation of the EGF receptor and the formation of a receptor complex comprising Shc, Grb2, Sos, and the EGF receptor. Dimerization or oligomerization of the EGF receptor was not induced by H2O2. Protein tyrosine phosphatase (PTP) assay showed that H2O2 suppressed dephosphorylation of the EGF receptor in cell lysates, suggesting that inactivation of PTP was involved in H2O2-induced activation of the EGF receptor. In contrast, the reductants N-acetyl-L-cysteine [Cys(Ac)] and dithiothreitol markedly suppressed EGF-induced dimerization and activation of the EGF receptor in cells. In accordance with suppression of the EGF receptor, Cys(Ac) suppressed EGF-induced activation of Ras, phosphatidylinositol 3-kinase and mitogen-activated protein kinase. Dithiothreitol completely inhibited EGF binding and kinase activation of the EGF receptor both in vitro and in vivo. In contrast, Cys(Ac) suppressed high-affinity EGF-binding sites on the cells, but had no effect on low-affinity binding sites. Furthermore, Cys(Ac) did not suppress EGF-induced kinase activation or dimerization of the EGF receptor in vitro, indicating that it suppressed the EGF receptor through a redox-sensitive cellular process or processes. Thus, the EGF receptor is regulated by redox through multiple steps including dephosphorylation by PTP, ligand binding, and a Cys(Ac)-sensitive cellular process or processes.

Animals↗
PubMed2000

c-fos expression in trigeminal spinal nucleus after electrical stimulation of the hypoglossal nerve in the rat.

The expression of the immediate early gene, c-fos, was used to determine the distribution of brainstem neurons activated by stimulation of the distal hypoglossal nerve (XIIn) trunk. The traditional view of the XIIn is one of purely motor function; however, stimulation of XIIn excites neurons in the trigeminal spinal nucleus. The rationale for this study was to use c-fos expression as a marker for postsynaptic activity to define the pattern of brainstem neurons excited by XIIn stimulation. It was further hypothesized that if the afferent fibers that course within XIIn supply deep lingual tissues, then c-fos expression after direct stimulation of XIIn should display a pattern similar to that seen after chemical irritant stimulation of the deep tongue muscle. In barbiturate-anesthetized male rats electrical stimulation of XIIn produced a significant increase in Fos-positive neurons in the dorsal paratrigeminal nucleus (dPa5) and laminae I-II of caudal subnucleus caudalis (Vc) and upper cervical dorsal horn. Mustard oil injection into the deep tongue muscle also produced an increase in c-fos expression in dPa5; however, the highest density of expression occurred in laminae I-II at the dorsomedial aspect of rostral Vc. Both electrical stimulation of XIIn and mustard oil stimulation of the deep tongue increased c-fos expression in the caudal ventrolateral medulla, an autonomic relay nucleus. These results suggest that one site of innervation for afferent fibers that travel within the distal trunk of XIIn is to supply the deep tongue muscle and to terminate in the dPa5. A second group of postsynaptic neurons activated only by XIIn stimulation was located in lamina I-II in caudal portions of Vc and upper cervical dorsal horn, a laminar distribution consistent with a role for XIIn afferents in sensory or autonomic aspects of lingual function.

Afferent Pathways↗
PubMed2000

Demonstration of Cl- requirement for inhibition of vacuolar acidification by cycloprodigiosin in situ.

Applying vacuole-perfusion and plasma membrane permeabilization techniques to internodal cells of Chara, we analyzed the requirement of Cl- for the action of cycloprodigiosin (cPrG) to inhibit vacuole acidification in situ. By combining the two techniques, the Cl- concentration on both sides of the tonoplast could be controlled. In permeabilized cell fragments lacking Cl- in the vacuole, the inhibitory effect of cPrG on vacuole acidification was cancelled. On the other hand, Cl- in the cytoplasm was not needed for the cPrG action. These results supported the function of cPrG as a H+/Cl- symporter. Requirement of Cl- for the cPrG action was also demonstrated in vacuole-perfused living cells. This is the first report on the mechanism of cPrG action in situ.

Acids↗
PubMed2000

Mutational evidence that the VPg is involved in the replication and not the movement of Pea enation mosaic virus-1.

Pea enation mosaic disease is caused by an obligatory association between the enamovirus Pea enation mosaic virus-1 (PEMV-1) and the umbravirus Pea enation mosaic virus-2 (PEMV-2). Encapsidated RNAs 1 and 2 are covalently linked to a 3138 Da VPg encoded by the RNA of PEMV-1. To determine the role of the VPg in the pathogenicity of PEMV (PEMV-1+PEMV-2), the infectivity of clones with mutations in key amino acids in the VPg was evaluated in protoplasts and in plants. Using quantitative, real-time RT-PCR, we concluded that the inability of certain mutants to infect plants was due to their replicative (and not their movement) incompetence. Mutant clones that produced delayed and less severe infections accumulated 10- to 100-fold less RNA-1 compared to WT-RNA-1 both in plants and in protoplasts. The RNAs of clones that produced WT-like infections accumulated to levels similar to those of WT-PEMV. Also, we demonstrate that the severity of symptoms produced by WT-PEMV is proportional to the amount of RNA-1 that accumulates in infected plants and seems to be independent of the amount of RNA-2. A dual role for the VPg in the pathogenicity of PEMV is proposed.

Amino Acid Sequence↗
PubMed2000

Cornea-responsive medullary dorsal horn neurons: modulation by local opioids and projections to thalamus and brain stem.

Previously, it was determined that microinjection of morphine into the caudal portion of subnucleus caudalis mimicked the facilitatory effects of intravenous morphine on cornea-responsive neurons recorded at the subnucleus interpolaris/caudalis (Vi/Vc) transition region. The aim of the present study was to determine the opioid receptor subtype(s) that mediate modulation of corneal units and to determine whether opioid drugs affected unique classes of units. Pulses of CO(2) gas applied to the cornea were used to excite neurons at the Vi/Vc ("rostral" neurons) and the caudalis/upper cervical spinal cord transition region (Vc/C1, "caudal" neurons) in barbiturate-anesthetized male rats. Microinjection of morphine sulfate (2.9-4.8 nmol) or the selective mu receptor agonist D-Ala, N-Me-Phe, Gly-ol-enkephalin (DAMGO; 1.8-15.0 pmol) into the caudal transition region enhanced the response in 7 of 27 (26%) rostral units to CO(2) pulses and depressed that of 10 units (37%). Microinjection of a selective delta ([D-Pen(2,5)] (DPDPE); 24-30 pmol) or kappa receptor agonist (U50488; 1.8-30.0 pmol) into the caudal transition region did not affect the CO(2)-evoked responses of rostral units. Caudal units were inhibited by local DAMGO or DPDPE but were not affected by U50,488H. The effects of DAMGO and DPDPE were reversed by naloxone (0.2 mg/kg iv). Intravenous morphine altered the CO(2)-evoked activity in a direction opposite to that of local DAMGO in 3 of 15 units, in the same direction as local DAMGO but with greater magnitude in 4 units, and in the same direction with equal magnitude as local DAMGO in 8 units. CO(2)-responsive rostral and caudal units projected to either the thalamic posterior nucleus/zona incerta region (PO/ZI) or the superior salivatory/facial nucleus region (SSN/VII). However, rostral units not responsive to CO(2) pulses projected only to SSN/VII and caudal units not responsive to CO(2) projected only to PO/ZI. It was concluded that the circuitry for opioid analgesia in corneal pain involves multiple sites of action: inhibition of neurons at the caudal transition region, by intersubnuclear connections to modulate rostral units, and by supraspinal sites. Local administration of opioid agonists modulated all classes of corneal units. Corneal stimulus modality was predictive of efferent projection status for rostral and caudal units to sensory thalamus and reflex areas of the brain stem.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗