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Biomedical subjects

M Aizawa

Publications and source records attributed to M Aizawa.

At least 55 records · Page 3Linked to original sources
PubMed1997

Electrically induced NGF production by astroglial cells.

A controlled culture system has been developed to induce nerve growth factor (NGF) production in astroglial cells that are cultured on an electrode surface. The electrode potential is alternatively modulated at an amplitude of 300 mV and a frequency of 10 Hz. The electric stimulation triggers NGF production and secretion. The mechanism of the electrically induced NGF production is discussed in association with protein kinase C (PKC) activation.

Animals↗
PubMed1997

Roles of gamma-aminobutyric acidB (GABA B) and gamma-hydroxybutyric acid receptors in hippocampal long-term potentiation and pathogenesis of absence seizures.

Experiments were performed to examine the roles of gamma-aminobutyric acid(B) (GABA(B)) and gamma-hydroxybutyric acid (GHB) receptors in long-term potentiation (LTP) of the hippocampal CA1 region in vivo and in the genesis of the spike and wave discharges (SWDs) associated with absence seizures. When tetanic stimulation was delivered to the CA3 region, stable LTP was observed in the CA1 region in saline-treated mice. In mice treated with 5 mg/kg baclofen, the population spike amplitude was significantly potentiated by tetanic stimulation and the degree of potentiation was the same as that induced in saline controls. However, this potentiation decayed to the baseline level about 90 min after stimulation. The decay was reversed by pretreatment with 200 mg/kg P-[3-aminopropyl]-P-diethoxymethylphosphinic acid (CGP 35348), a selective GABA(B) receptor antagonist. In mice treated with 50 mg/kg gamma-butyrolactone (GBL), a prodrug of GHB, stable LTP was observed 90 min after tetanic stimulation and was greater than that in saline controls. GBL-induced potentiation of LTP was antagonized by 50 mg/kg NCS 382, a putative GHB receptor antagonist. Administration of baclofen (20 mg/kg) or GBL (70 mg/kg) induced absence-like seizures associated with 3-6 Hz SWDs, and CGP 35348 suppressed both baclofen- and GBL-induced SWDs. NCS 382 also attenuated SWDs induced by GBL and baclofen. These results suggest that baclofen and GHB have different effects on LTP in the CA1 region of the hippocampus in vivo, although they have a common mode of action on the thalamocortical functions related to the pathogenesis of absence seizures.

4-Butyrolactone↗
PubMed1997

[Contractility of the striated urethral sphincter in dogs--an analysis with pressure-time curve and ATPase stain method].

PURPOSE: A comparative study about the contractility of the external urethral sphincter in the pelvic floor muscle (PFM) and about that of the periurethral striated sphincter (PUS), which is independent of PFM, was made by employing adult male mongrels. METHODS: This study was done by using the compression-time curve. Moreover, the study about the formation of muscle fibers was carried out by the aid of ATPase staining. RESULTS: Stimulus to one side of pudendal nerve increased each sphincter M-wave amplitudes and its compressive differences in contraction. Easy repetitions of the experiment made it possible to use the compression-time curve. The compressive differences in the urethral contraction was significantly greater in the urethra of PUS than in that of PFM. Data obtained from the compressive-time curve showed PUS premotor time was significantly longer than PFM in electromyograms, PUS motor time and time to peak force was significantly shorter, and PUS rate of force development was significantly faster. The histochemical study showed that fast muscles account for 70% in PUS, while they account for approximate 50% in PFM, which supported the results of the compression-time curve. CONCLUSION: The above suggested the contractility of PUS apparently differed from that of PFM; PUS contracts quickly, while PFM contracts slowly. Also, it seemed that forming conjectures with the compression-time curve on the formation of muscle fibers in the striated urethral sphincters were possible to some degree.

Adenosine Triphosphatases↗
PubMed1996

Differentiation effect of acyclic retinoid on acute promyelocytic leukemia cells.

Acyclic retinoid (all-trans-3, 7, 11, 15-tetramethyl-2, 4, 6, 10, 14-hexadecapentaenoic acid) binds cellular retinoic acid-binding protein with an affinity similar to that of all-trans retinoic acid and induces differentiation of human hepatoma cell lines and a human acute myelogenous leukemia cell line (HL-60). We investigated the in vitro efficacy of acyclic retinoid to induce the differentiation of acute promyelocytic leukemia (APL) cells using primary cultured cells obtained from 11 APL patients. Five days' incubation with acyclic retinoid effected a dose-dependent induction of differentiation. Cells from eight patients showed maximum differentiation at 10(-6) M acyclic retinoid. Cells from one patient required 10(-5) M for maximum differentiation, while those from two patients exhibited moderate differentiation at 10(-5) M. Five days' incubation with acyclic retinoid (10(-7) approximately 10(-5) M) did not affect the viability or number of cells from any patient except one, whose cells showed a slight decrease in viability at 10(-5) M. Thus, we conclude that acyclic retinoid induced the differentiation of primary cultured APL cells at concentrations of 10(-6) approximately 10(-5) M, a range at which it is not toxic.

Antineoplastic Agents↗
PubMed1996

gamma-Butyrolactone-induced absence-like seizures increase nuclear CRE- and AP-1 DNA-binding activities in mouse brain.

We examined the involvement of the GABAB receptor and the coordinated induction of nuclear transcriptional factors in experimental generalized absence seizures induced by gamma-butyrolactone (GBL) in mice. Although administration of GBL 50 mg/kg did not show any effects on behavior or ECoG pattern, higher doses of GBL (70 and 100 mg/kg, i.p.) induced behavioral changes associated with 3-6-Hz spike and wave discharges in the mice. CGP 35348, a GABAB receptor antagonist, suppressed both the GBL-induced absence seizures and the spike and wave discharges. The antiepileptic effects of CGP 35348 (200 mg/kg, i.p.) were stronger than those of ethosuximide (200 mg/kg, i.p.). Sodium valproate (100 mg/kg, i.p.) attenuated the early phase but not the late phase of the GBL-induced absence seizures. Gel-mobility assay demonstrated that administration of an effective dose of GBL for eliciting spike and wave discharges dose-dependently increased nuclear cyclic AMP-responsive element (CRE)- and activator protein 1 (AP-1) DNA-binding activities in mouse whole brain. The increases in nuclear CRE- and AP-1 DNA-binding were antagonized by CGP 35348 in a dose-dependent fashion. In addition, GABAB receptor binding assay revealed that GBL or antiepileptic drugs did not displace [3H]baclofen binding in cerebral cortical membranes. In contrast, gamma-hydroxybutyrate (GHB), an active metabolite of GBL, inhibited [3H]baclofen binding in a concentration-dependent manner. These results suggest that GABAB receptor-mediated synaptic responses are involved in GBL-induced generalized absence seizures and that the increases in nuclear CRE- and AP-1 DNA-binding activities are correlated with the GBL-induced generalized absence seizures.

4-Butyrolactone↗
PubMed1996

Inhibitory effects of green tea polyphenols on growth and cellular adherence of an oral bacterium, Porphyromonas gingivalis.

Effects of polyphenolic compounds isolated from green tea (Camellia sinensis) on the growth and adherence of Porphyromonas gingivalis onto human buccal epithelial cells were investigated. Green tea polyphenols, especially (-)-epigallocatechin gallate (EGCg) which is a dominant component of tea polyphenols, completely inhibited the growth and adherence of P. gingivalis onto the buccal epithelial cells at concentrations of 250-500 micrograms/ml. Among the polyphenolic compounds, (-)-epicatechin gallate (ECg) and (-)-gallocatechin gallate (GCg) were effective next to EGCg in these activities. On the other hand, (+)-catechin (C(+)), (-)-epicatechin (EC), (+)-gallocatechin (GC), and (-)-epigallocatechin (EGC) had very much less activity. These results indicate that the inhibitory effect on the adherence of P. gingivalis onto the buccal epithelial cells is attributed to the presence of the galloyl moiety, which is ester-linked with the 3-OH of the catechin moiety in the polyphenolic compounds.

Bacterial Adhesion↗
PubMed1996

[Urological assessment for tethered cord syndrome of delayed onset following repair of meningomyelocele].

UNLABELLED: PURPOSE AND MATERIALS: Out of 84 patients with meningomyelocele repaired at birth, 14 (15. 7%) children (6 boys and 8 girls, average 8.8 year-old) who underwent cord untethering for tethered cord syndrome of delayed onset (Delayed TCS) were urologically evaluated. RESULTS: Eleven (78.5%) children were detected orthopedically by deterioration of lower extermities function and only 3 (21.5%) were detected urologically. Preoperative urodynamic study, however, revealed in 5 children aggravation of urinary tract dysfunction, including accelerated uninhibited contraction in 4, impaired bladder compliance in 3, decreased bladder capacity in 2 and recurrence of VUR in 1. Although there were no particular urinary symptom for detection of Delayed TCS, acceleration of uninhibited contraction seemed to be one of the most important findings. After untethering, deterioration or normalization of urological dysfunction was not seen. Six of 14 children had favorable clinical results, such as improvement of uninhibited contraction, increasing of bladder compliance and capacity, prolongation of dry time and disappearance of VUR. In 3 children Delayed TCS were detected by postoperative improvement of urinary tract function. Consequently, of 14 children who were evaluated preoperatively and postoperatively 8 (52. 7%) had urological impairment compatible with Delayed TCS. CONCLUSIONS: It is not easy to detect the urological deteriorations associated with Delayed TCS behind initial neuro-urological deficits. Careful and regular follow-up examinations are required to early detection of Delayed TCS. The fact that urinary tract dysfunction improved in some cases after untethering encourages aggressive surgical untehtering of Delayed TCS.

Adolescent↗
PubMed1995

Bioluminescent detection of RNA with sequence-specificity using RNA binding protein-luciferase fusion protein.

A novel bifunctional reagent has been synthesized for RNA detection by genetic fusion of a sequence-specific RNA binding protein and firefly luciferase. The RNA binding protein used in this study recognizes the oligoribonucleotide rH4 which contains four (UUAGGG)-repeat sequence, while luciferase works as a bioluminescent marker. The constructed fusion protein exhibited both sequence-specific RNA binding and bioluminescent activities. The rH4 and rECGF, which has an unrelated sequence having the same length as rH4, were immobilized on a nylon membrane. The membrane was pre-treated by 5% bovine serum albumin and soaked into a fusion protein solution. Bioluminescent detection has successfully been performed at more than 50 pmol of rH4, so the detection limit using this protein was 50 pmol. However, no appreciable bioluminescence was induced by rECGF.

Base Sequence↗
PubMed1995

The UUAG-specific RNA binding protein, heterogeneous nuclear ribonucleoprotein D0. Common modular structure and binding properties of the 2xRBD-Gly family.

Human cDNA clones encoding the UUAG-binding heterogeneous nuclear ribonucleoprotein (hnRNP) D0 protein have been isolated and expressed. The protein has two RNA-binding domains (RBDs) in the middle part of the protein and an RGG box, a region rich in glycine and arginine residues, in the C-terminal part ("2xRBD-Gly" structure). The hnRNP A1, A2/B1, and D0 proteins, all possess common features of the 2xRBD-Gly structure and binding specificity toward RNA. Together, they form a subfamily of RBD class RNA binding proteins (the 2xRBD-Gly family). One of the structural characteristics shared by these proteins is the presence of several isoforms presumably resulting from alternative splicing. Filter binding assays, using the recombinant hnRNP D0 proteins that have one of the two RBDs, indicated that one RBD specifically binds to the UUAG sequence. However, two isoforms with or without a 19-amino acid insertion at the N-terminal RBD showed different preference toward mutant RNA substrates. The 19-amino acid insertion is located in the N-terminal end of the first RBD. This result establishes the participation of the N terminus of RBD in determining the sequence specificity of binding. A similar insertion was also reported with the hnRNP A2/B1 proteins. Thus, it might be possible that this type of insertion with the 2xRBD-Gly type RNA binding proteins plays a role in "fine tuning" the specificity of RNA binding. RBD is supposed to bind with RNA in general and sequence-specific manners. These two discernible binding modes are proposed to be performed by different regions of the RBD. A structural model of these two binding sites is presented.

Alternative Splicing↗
PubMed1995

Production of the chimeric-binding protein, maltose-binding protein-protein A, by gene fusion.

A fusion protein between maltose-binding protein (MBP) and staphylococcal protein A (SpA) was genetically produced. The gene fusion plasmid, pMALPA2, was constructed by inserting the protein A gene into an expression vector of maltose-binding protein in frame, and was expressed efficiently in Escherichia coli. The resulting fusion protein of molecular mass 65 kDa, retained the activity of both MBP and SpA (binding capability to amylose and immunoglobulin G). This chimeric-binding protein was used as an adhesive molecule for immobilization of antibodies to a solid-phase surface for enzyme immunoassay. An enzyme immunoassay was performed with the fusion protein, and human IgG was determined in the concentration range from 10(-4) to 10(-6) g ml-1.

ATP-Binding Cassette Transporters↗
PubMed1995

Biosensing of benzene derivatives in the environment by luminescent Escherichia coli.

Sensitive and convenient biosensing of environmental pollutants has been developed by fusing a gene of firefly luciferase to the TOL plasmid. TOL plasmid of Pseudomonas putida encodes a series of enzymes for degradation of benzene and its derivatives. The expression of these enzymes is controlled with the regulating proteins xylR and xylS, whose promoters are activated in the presence of aromatic compounds. The structural gene of firefly luciferase, as a reporter enzyme, was inserted under the control of the promoter of xylS protein, and gene fusion plasmid pTSN316 was constructed. The recombinant Escherichia coli transformed with this plasmid was applied to the environmental biosensing of benzene derivatives. The expression of luciferase was induced in the presence of aromatic compounds and the lower detection limit for m-xylene was 5 microM.

Benzene↗
PubMed1994

Multilabeling of ferrocenes to a glucose oxidase-digoxin conjugate for the development of a homogeneous electroenzymatic immunoassay.

A new homogeneous electroenzymatic immunoassay was developed to determine antibody concentration using glucose oxidase and ferrocene as enzymatic and electrochemical amplifier, respectively. Digoxin (Dig)-conjugated glucose oxidase (GOx) was modified with ferrocene (Fec) to form Fec-GOx-Dig conjugate. After immunocomplex formation between the Fec-GOx-Dig conjugate and the anti-digoxin antibody, the complex underwent less electrochemical reaction due to the steric hindrance of the antibody. The ferrocene multilabeled conjugate was provided for the determination of anti-digoxin antibody. Since the strategy taken here is based on a combined effect of GOx and ferrocene, i.e., enzymatic amplification by GOx and electrochemical amplification by multilabeled ferrocenes, the antibody concentration was determined in the range from 1/50 to 1/500 dilution.

Animals↗
PubMed1994

Molecular characterization of a mouse prostaglandin D receptor and functional expression of the cloned gene.

Prostanoid receptors belong to the family of G protein-coupled receptors with seven transmembrane domains. By taking advantage of nucleotide sequence homology among the prostanoid receptors, we have isolated and identified a cDNA fragment and its gene encoding a mouse prostaglandin (PG) D receptor by reverse transcription polymerase chain reaction and gene cloning. This gene codes for a polypeptide of 357 amino acids, with a calculated molecular weight of 40,012. The deduced amino acid sequence has a high degree of similarity with the mouse PGI receptor and the EP2 subtype of the PGE receptor, which together form a subgroup of the prostanoid receptors. Chinese hamster ovary cells stably expressing the gene showed a single class of binding sites for [#H]PGD2 with a Kd of 40 nM. This binding was displaced by unlabeled ligands in the following order: PGD2 > BW 245C (a PGD agonist) > BW A868C (a PGD antagonist) > STA2 (a thromboxane A2 agonist). PGE2, PGF2 alpha, and iloprost showed little displacement activity at concentrations up to 10 microM. PGD2 and BW 245C also increased cAMP levels in Chinese hamster ovary cells expressing the receptor, in a concentration-dependent manner. BW A868C showed a partial agonist activity in the cAMP assay. Northern blotting analysis with mouse poly(A)+ RNA identified a major mRNA species of 3.5 kb that was most abundantly expressed in the ileum, followed by lung, stomach, and uterus.

Amino Acid Sequence↗
PubMed1994

Determination of synthetic food dyes by capillary electrophoresis.

A method for the determination of synthetic tar dyes used as food additives using capillary electrophoresis with photodiode-array detection was investigated. The dyes Erythrosine (R-3), Phloxine (R-104), Rose Bengal (R-105), Acid Red (R-106), Amaranth (R-2), New Coccine (R-102) and Allura Red AC (R-40) were separated on a capillary column (50 cm x 75 microns I.D.) and identified from the absorbance spectra of each peak. The electrophoresis buffer used was a mixture of 25 mM sodium phosphate buffer and 25 mM sodium borate buffer (1:1) (pH 8.0) containing 10 mM sodium dodecyl sulfate (SDS). Substitution of beta-cyclodextrin for SDS in the electrolyte buffer was effective for the separation of R-2 and R-102. This modified method could be employed as an additional assay method for these two dyes.

Amaranth Dye↗