Biomedical subjects

H Sato

Publications and source records attributed to H Sato.

At least 289 records · Page 16Linked to original sources

PubMed2000

Unique substrate specificities of two adjacent glutamine residues in EAQQIVM for transglutaminase: identification and characterization of the reaction products by electrospray ionization tandem mass spectrometry.

Reversed-phase HPLC (RP-HPLC) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) were used to characterize the transglutaminase (TGase)-catalyzed dual modification of a peptide (EAQQIVM, named FibN) with monodansylcadaverine (MDC). The synthesized FibN peptide, which was derived from the N-terminal sequence of fibronectin, was used as the substrate for a guinea pig liver TGase (G-TGase). The time course of incorporation of MDC into FibN, detected by RP-HPLC, indicated two separate fluorescent product peaks. ESI-MS analysis of the isolated fractions indicated that products represented MDC-incorporated FibN molecules in molar ratios of 1:1 ((MDC)-FibN) and 2:1 ((MDC)2-FibN). A sequence analysis of MDC-FibN, using ESI-MS/MS, showed that the first modified residue in FibN was mainly Gln3. The kinetic analysis of MDC incorporation suggested that dual incorporation would occur by mainly one route. A one-dimensional 1H NMR comparison of MDC-FibN and unmodified FibN suggested that the first incorporation of MDC at Gln3 altered the substrate reactivity of the Gln4 residue in FibN for the G-TGase-catalyzed reaction. Thus, a detailed analysis of the peptide products using RP-HPLC and ESI-MS/MS should provide a powerful tool for exploring the mechanism of the substrate requirements of TGases.

Animals↗

PubMed2000

Exceptionally potent inhibitors of fatty acid amide hydrolase: the enzyme responsible for degradation of endogenous oleamide and anandamide.

The development of exceptionally potent inhibitors of fatty acid amide hydrolase (FAAH), the enzyme responsible for the degradation of oleamide (an endogenous sleep-inducing lipid), and anandamide (an endogenous ligand for cannabinoid receptors) is detailed. The inhibitors may serve as useful tools to clarify the role of endogenous oleamide and anandamide and may prove to be useful therapeutic agents for the treatment of sleep disorders or pain. The combination of several features-an optimal C12-C8 chain length, pi-unsaturation introduction at the corresponding arachidonoyl Delta(8,9)/Delta(11,12) and oleoyl Delta(9,10) location, and an alpha-keto N4 oxazolopyridine with incorporation of a second weakly basic nitrogen provided FAAH inhibitors with K(i)s that drop below 200 pM and are 10(2)-10(3) times more potent than the corresponding trifluoromethyl ketones.

Amidohydrolases↗

PubMed2000

Aspirin inhibits tumor cell invasiveness induced by Epstein-Barr virus latent membrane protein 1 through suppression of matrix metalloproteinase-9 expression.

Matrix metalloproteinases (MMPs) are thought to play crucial roles in tumor invasion and metastasis. Because we have shown that EBV latent membrane protein 1 (LMP1) enhances MMP-9 expression by activation of nuclear factor (NF)-kappaB and activator protein (AP)-1 (T. Yoshizaki, et al., Proc. Natl. Acad. Sci. USA, 95: 3621-3626, 1998), we therefore tested whether up-regulation of MMP-9 by LMP1 could be correlated with enhanced invasiveness of tumor cells in vitro. Whether aspirin and sodium salicylate could reduce invasiveness and whether LMP1 could enhance MMP-9 expression in tumors grown in nude mice were also tested. C33A cells stably expressing LMP1 had increased expression of MMP-9 and showed greater invasion through reconstituted basement membrane compared with vector-transfected C33A cells (P < 0.02). Treatment with aspirin or sodium salicylate inhibited invasiveness of the LMP1-expressing C33A cells (P < 0.03) and suppressed both the LMP1-induced MMP-9 expression in zymographic analyses and LMP1-induced MMP-9 promoter activity in CAT reporter assays (P < 0.01). Endogenous MMP-2 levels were unaffected by either drug. Both drugs repressed the CAT activity of the truncated MMP-9 promoter construct, which only contained a binding site for AP-1, to the basal level (P < 0.05). Moreover, EMSA indicated that the effects of the salicylates were through the inhibition of not only NF-kappaB but also AP-1 binding activity. Inhibitory effect of salicylates could be reversed by p50/p65 subunits of NF-kappaB or c-Jun overexpression. The inhibitory effect of aspirin on NF-kappaB activity was attributable to the inhibition of IkappaB kinase activity. Finally, tumors derived from C33A cells stably expressing LMP1 grown in nude mice showed enhanced MMP-9 levels compared with tumors derived from vector-transfected C33A cells. This enhancement was inhibited by treatment of the mice with aspirin. These results suggest that aspirin may be able to suppress invasion and metastasis of EBV-associated tumors that express LMP1 by suppression of MMP-9.

Animals↗

PubMed2000

Effect of synthesized cyclohexanol derivatives using L-menthol as a lead compound on the percutaneous absorption of ketoprofen.

L-Menthol was selected as a lead compound to synthesize new candidates for percutaneous absorption enhancers. In a previous study, O-ethylmenthol (MET) was the most effective compound and caused relatively little skin irritation. To develop more effective compounds, mono- or disubstitute groups of cyclohexane with an O-ethyl group were synthesized. Some 35 compounds were synthesized and evaluated for their promoting activity and effect on skin. An in vivo percutaneous absorption study was performed using rats with hydrogel containing ketoprofen and each of the synthesized compounds. The plasma concentration of ketoprofen was determined after the application of hydrogel to the abdominal area of rats. The apparent penetration rate (R(p)) was estimated based on the pharmacokinetic model with a constant rate of penetration through the skin after the lag time. The 2-compartment model was applied to the data obtained from the iv administration. As an index to evaluate the promoting activity of each enhancer, an enhancement factor (E(f)) was defined as follows: E(f) = R(p) (with enhancer)/R(p) (without enhancer). Irritation to skin was pathologically evaluated. The treated area of rat abdominal skin was excised after the in vivo experiment using total irritation score (TIS). The compound having a C-3 positioned iso-butyl group on the chemical structure was the most effective and caused relatively little irritation among mono-substituted compounds. In the case of di-substituted compounds, all had the same effect as or a stronger effect than MET. Furthermore, the promoting activity almost corresponded to irritation. To estimate log P, one of the physicochemical properties of molecules, a computer program 'CAChe' was employed. The log P was calculated using the atom typing scheme. Multiple regression analysis revealed that the relations between E(f) or TIS and log P were parabolic. It was suggested that the optimum logP value reflects the promoting activity to enhance percutaneous absorption of ketoprofen.

Animals↗

PubMed2000

Humoral immunoresponse to varicella-zoster virus pernasally coadministered with Escherichia coli enterotoxin in mice.

It is evaluated whether Escherichia coli enterotoxin is useful for induction of immunity to varicella-zoster virus (VZV) as a mucosal adjuvant in mice. When a commercially available live varicella vaccine (Oka strain) and toxin were administered simultaneously via a nasal route three times at 2 or 6 month intervals, an antibody neutralizing VZV was detected in half or all of the mice vaccinated, respectively. The antibody specific to the vaccine strain of VZV reacted to five proteins, molecular weights of which were 110 K, 100 K, 62 K, 54 K and 46 K. These proteins were composed of glycosylated products of all kinds of glycoproteins. These results suggest that although a nasal administration of the vaccine without the adjuvant has little immunogenicity in mice, the simultaneous administration of the live vaccine and the toxin over a long period induces a specific humoral immunity to VZV.

Adjuvants, Immunologic↗

PubMed2000

In vivo gene gun-mediated DNA delivery into rodent brain tissue.

Various types of gene transfer into live tissues have been tried. However, in vivo gene transfer into brain tissue or neuronal cells without virus vector has required a great effort. Particle-mediated gene transfer into live brain tissue was thought to be impossible because of its fragility and the mechanical problem of a previous type of gene gun. In addition, particle-mediated DNA transfer into monolayer-cultured cells without mechanical damage has been difficult. We successfully transferred DNA into rodent live brain tissue and also into monolayer-cultured cells without mechanical damage by using a new type of gene gun and also confirmed gene expression in the brain. This new method represents another variation of gene transfer into the brain.

Animals↗

PubMed2000

Transformation of Madin-Darby canine kidney (MDCK) epithelial cells by Epstein-Barr virus latent membrane protein 1 (LMP1) induces expression of Ets1 and invasive growth.

The Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) has a significant role in initiating EBV-associated lymphoproliferative disease and EBV-related malignancies. In view of clinical features related to the type of EBV latency, LMP1 may influence invasiveness of EBV associated tumors categorized as types II and III as represented on nasopharyngeal carcinoma (NPC). To screen for genes associated with invasion of epithelial cells transformed by LMP1, Madin-Darby canine kidney (MDCK) epithelial cells were transformed by LMP1. Stable transfection of a LMP1 gene into MDCK cells induced morphological change from cobblestone to a long spindle-shape, reduced cell-cell adhesion and caused high cell motility. Parental MDCK cells, which form spherical cysts in three-dimensional collagen gel matrix, form branching tubules following exposure to hepatocyte growth factor (HGF). MDCK cells transformed by LMP1 showed invasive growth to form branching tubules into collagen gel without HGF-treatment. mRNA differential display and Northern hybridization identified plasminogen activator inhibitor-1 (PAI-1), urokinase type plasminogen activator (uPA) and ets1 as genes upregulated during transformation by LMP1. Expression of a dominant negative type of Etsl in LMP1-transformed cells downregulated uPA expression and cell motility. Deletion of LMP1 cytoplasmic carboxy-terminal activating region 1 (CTAR1) domain abolished transformation, but a deletion mutant lacking CTAR2 domain still retained transforming and uPA-inducing ability. Expression of Ets1 was immunolocalized in tumor cells of NPC tissue which frequently express LMP1. Taken together, it is suggested that LMP1 induces expression of Ets1 which may contribute to invasion of NPC by stimulating cell motility and uPA expression.

Animals↗

PubMed2000

Properties of horizontal and vertical inputs to pyramidal cells in the superficial layers of the cat visual cortex.

The purpose of this study is to elucidate the integrative input mechanisms of pyramidal cells receiving horizontally projecting axon collaterals (horizontal projection) and vertical input from layer IV. We performed whole-cell recordings from pyramidal cells in layer II/III and focally activated other single pyramidal cells monosynaptically connected via long-distance horizontal (LH) projections (the distance between presynaptic and postsynaptic cells was 350-1200 micrometer) in slice preparations of the kitten primary visual cortex. In addition, presynaptic single fibers in layer IV (vertical input) and/or short-distance horizontal (SH) inputs from neighboring single pyramidal cells (distance within 100 micrometer) in layer II/III were activated. Unitary EPSPs evoked by the activation of LH and SH connections had smaller amplitude and larger coefficient of variation than those evoked by stimulating the vertical input. Paired-pulse stimulation of the LH and SH inputs caused the depression of the second EPSP, whereas that of vertical inputs caused either facilitation or depression of the second EPSP. The EPSPs evoked by simultaneous activation of LH and vertical inputs summated linearly at the resting membrane potential. However, the EPSPs evoked by stimulation of the two inputs were nonlinearly (supralinearly) summated when the postsynaptic membrane was depolarized to a certain level. Similar EPSP interaction was observed in response to simultaneous activation of the LH and SH inputs.

Animals↗

PubMed2000

Disordered magnetism at the metal-insulator threshold in nano-graphite-based carbon materials

The magnetism of activated carbon fibers composed of a disorder network of nanographites was investigated, where each nanographite has about 1 edge-inherited localized spin. The susceptibility, for samples situated around the metal-insulator threshold, shows a cusp around 4-7 K in addition to the presence of a field-cooling effect. These behaviors are explained in terms of disordered magnetism caused by random strengths of inter-nano-graphite antiferromagnetic interactions mediated by pi-conduction carriers.

Journal Article↗

PubMed2000

Effect of hypoxia on nitric oxide production and its synthase gene expression in rat smooth muscle cells.

It has not been clarified yet as to whether hypoxia and inflammation affect NO synthesis. In this study, we investigated the transcription of inducible nitric oxide synthase (iNOS) mRNA and the production of nitric oxide (NO) in rat smooth muscle cells (SMCs) cultured under hypoxic conditions in the presence and absence of proinflammatory cytokine interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS). We found that hypoxia inhibited the production of NO but did not affect the transcription of iNOS mRNA in rat SMCs treated with IFN-gamma, LPS, or both. These results indicate that O(2) is involved in the regulation of NO synthesis in inflammatory tissues.

Animals↗

PubMed2000

Determination of erythromycin, clarithromycin, roxithromycin, and azithromycin in plasma by high-performance liquid chromatography with amperometric detection.

In this study, a high-performance liquid chromatographic method was developed for the quantitative determination of erythromycin (EM), roxithromycin (RXM), and azithromycin (AZM) in rat plasma with amperometric detection under a standardized common condition using clarithromycin (CAM) as an internal standard. This method was also proved to be applicable for the determination of CAM by employing RXM as an internal standard. Each drug was extracted from 150 microl of plasma sample spiked with internal standard under an alkaline condition with tert.-butyl methyl ether. The detector cell potential for the oxidation of the drugs was set at +950 mV. The linearity of the calibration curves were preserved over the concentration ranges of 0.1-10 microg/ml for EM and RXM, and 0.03-3.0 microg/ml for CAM and AZM. Coefficients of variation and relative error were less than 9% and +/-7%, respectively. The analytical method presented here was proved to be useful for the investigation of the pharmacokinetic characteristics of EM, CAM, RXM, and AZM in rats.

Animals↗

PubMed2000

Human membrane type-2 matrix metalloproteinase is defective in cell-associated activation of progelatinase A.

Transfection of the mouse membrane type-2 matrix metalloproteinase (MT2-MMP) gene into COS-1 cells resulted in activation of progelatinase A; however, that of the human gene had no effect. Expression of human and mouse MT2-MMP chimeric proteins revealed the defect of human MT2-MMP which resides in the region between amino acid (aa) residues 155 and 271. Seven aa residues in this region were not conserved between human and mouse MT2-MMP. Substitution with the corresponding mouse residue, proline-183 to serine and glutamine-185 to aspartic acid, recovered cell-associated progelatinase A activation function. These residues are located in the insertion sequence-2 (IS-2), which was conserved in six clones of the human MT2-MMP gene from different sources, except that of proline-183 which was substituted with serine from HT1080 cells. These results indicate that human MT2-MMP is defective in cell-associated activation of progelatinase A, and this is attributed to IS-2. These findings emphasize the importance of IS-2 in MT2-MMP functionality.

Amino Acid Sequence↗

PubMed2000

Structure-activity relationships of trans-3,5-disubstituted pyrrolidinylthio-1beta-methylcarbapenems. Part 2: J-111,225, J-114,870, J-114,871 and related compounds.

Through further derivatization of J-111,347 (1a), a trans-3,5-disubstituted pyrrolidinylthio-1beta-methylcarbapenem, undesired epileptogenicity in a rat intracerebroventricular assay (200 microg/rat) could be eliminated to afford J-111,225 (2a), J-114,870 (3a) and J-114,871 (3b) which preserved comparable broad antimicrobial activity.

Carbapenems↗

PubMed2000

Structure-activity relationships of trans-3,5-disubstituted pyrrolidinylthio-1beta-methylcarbapenems. Part 1: J-111,347 and related compounds.

1Beta-methylcarbapenems having various 3,5-disubstituted pyrrolidinylthio-side chains at C-2 were designed and synthesized. Evaluation of their antibacterial activities indicated that J-111,347 (1a) is the first example of an extremely broad spectrum antibiotic showing activity against methicillin-resistant Staphylococcus aureus (MRSA) as well as Pseudomonas aeruginosa.

Anti-Bacterial Agents↗

PubMed2000

Neuronal organization of the utricular macula concerned with innervation of single vestibular neurons in the cat.

We investigated whether cross-striolar inhibition, which may increase sensitivity to linear acceleration, contributed to utricular (UT) afferent innervation of single vestibular neurons (VNs). Excitatory and inhibitory postsynaptic potentials (EPSPs, IPSPs, respectively) were recorded from VNs after focal stimulation of the UT macula (M). From a total of 83 VNs, 25 (30%) neurons received inputs from both sides of the UTM, and the response patterns were opposite, i.e. cross-striolar inhibition was observed. In roughly 2/3 of these neurons, stimulation of the medial side of the UTM evoked EPSPs, while stimulation of the lateral side evoked IPSPs. In the remaining 1/3 neurons, the response patterns were opposite. Thirty-two (39%) of the 83 neurons received the identical pattern of inputs from both sides of the UTM: EPSPs in 26 neurons and IPSPs in six neurons. Twenty-six (31%) of the 83 neurons received inputs from either the medial or the lateral side of the UTM. These findings suggest that cross-striolar inhibition existed in the UT system, although it was not a dominant circuit that increased the sensitivity as in the saccular system [15].

Acoustic Maculae↗

PubMed2000

Subclinical neurophysiological effects of lead: A review on peripheral, central, and autonomic nervous system effects in lead workers.

BACKGROUND: The peripheral nerve conduction velocity (NCV), distribution of nerve conduction velocities (DCV), somatosensory, visual, and brainstem auditory evoked potentials (SEP, VEP, and BAEP, respectively), event-related potential (P300), computerized static posturography with spectral analysis (postural balance), and electrocardiographic R-R interval variability (CV(RR)) with spectral analysis appear to be promising techniques for assessing subclinical effects of lead on the peripheral, central and autonomic nervous systems. This article presents an overview of research addressing subclinical neurophysiological effects of lead in workers exposed to lead. METHODS: We reviewed 102 articles to examine the effects and dose-effects relationships of lead on peripheral, central, and autonomic nervous system function together with reversibility of the effects, interaction between lead and other metals, and relative sensitivity and specificity of each technique. Background and methodology were also reviewed. RESULTS AND CONCLUSION: Available data suggest that, on a group basis, the reduction in the NCV, together with the effects on the P300 latency, postural balance, and CV(RR), occurs at a mean blood lead concentration (BPb) as low as 30-40 microg/dL; the effects on the latencies of the short-latency SEP, VEP, and BAEP, as well as the DCV, start at a BPb as low as 40-50 microg/dL. Further cross-sectional and preferably prospective studies by using each of those methods are needed to establish more precise dose-effects (and response) relationships of lead.

Autonomic Nervous System↗

PubMed2000

Splenomegaly and chronic disseminated intravascular coagulation in Osler-Weber-Rendu disease: a case report.

A 45-year-old Japanese woman with splenomegaly and thrombocytopenia was referred to our hospital. The diagnosis of Osler-Weber-Rendu disease (Osler's disease) was made because of spotty telangiectasia on her tongue, recurrent epistaxis since childhood, and a diathesis indicated by her family history. The patient's laboratory examination revealed anemia, thrombocytopenia, and other data consistent with chronic disseminated intravascular coagulation (DIC). Bone marrow examination was normal. Abdominal computed tomography showed marked enlargement of the spleen with deformity and calcified plaque, not homogeneously enhancing. Hypersplenism was not observed. Platelet scintigraphy indicated a remarkable uptake in the spleen. She was diagnosed as having chronic DIC associated with vascular lesions of Osler's disease in the spleen. Splenectomy was performed and the subsequent pathological findings indicated that fragility of the fine vascular architecture of the splenic red pulp might have been responsible for pathogenesis. The large pooling of blood with coagulation was thought to be secondary.

Disseminated Intravascular Coagulation↗

PubMed2000

Four putative subtypes of human parvovirus B19 based on amino acid polymorphism in the C-terminal region of non-structural protein.

The nucleotide sequence of 10 isolates of human parvovirus B19 (B19) were determined and compared throughout 96.3% of the open reading frames (4145 nucleotides from nt. 509-4653). In the 4145 nucleotides, 122 mutation sites were found, of which 24 were accompanied by amino acid displacement. Furthermore, the polymorphism of the amino acids was seen in about 110 bases near the carboxy terminal of the non-structural protein, ranging from nt. 2011 to 2123, where four amino acid mutation points were found to exist. Based on the amino acid polymorphism of these four mutation sites in this area, 10 isolates of the B19 parvovirus could be divided into 4 subtypes (subtypes A, B, C, and D). The frequency of isolation of the subtypes depended on the time and location of collection of the B19 viremic blood specimens.

Amino Acid Sequence↗