Biomedical subjects

T Kikuchi

Publications and source records attributed to T Kikuchi.

At least 199 records · Page 11Linked to original sources

PubMed1999

[In vitro activity of biapenem (BIPM) against clinically isolated respiratory pathogens in 1996-1998].

The in vitro antibacterial activity of biapenem (BIPM), a new carbapenem antibiotic, was compared with those of imipenem (IPM), panipenem (PAPM), meropenem (MEPM), ceftazidime (CAZ) and piperacillin (PIPC) against 280 isolates of 9 respiratory pathogens. The MIC90s of biapenem (BIPM) for methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, Moraxella catarrhalis, Pseudomonas aeruginosa, and Haemophilus influenzae were 0.12, 32, 0.25, 0.06, 4 and 8 micrograms/ml, respectively. In comparison with other antibiotics, the activity of biapenem (BIPM) for P. aeruginosa was as potent as meropenem (MEPM), but for H. influenzae it was slightly less than those of other antibiotics, and for other respiratory pathogens it was as potent as those of other antibiotics. The MIC90s of biapenem (BIPM) for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae and Serratia marcescens were 0.06, 1, 1, 0.5 microgram/ml, respectively, and which were equal to or somewhat lower than those of other antibiotics. Biapenem (BIPM) showed strong activity against Gram-positive and Gram-negative pathogens, especially P. aeruginosa in general. Based on these results, biapenem (BIPM) is seemed to be highly useful antibiotic for the treatment of respiratory infections with several organism.

Bacteria↗

PubMed1998

Density of motility-related charge in the outer hair cell of the guinea pig is inversely related to best frequency.

Whole cell voltage clamp and freeze fracture were used to study the electrophysiological and ultrastructural correlates of the outer hair cell (OHC) lateral membrane molecular motors. We find that specific voltage-dependent capacitance, which derives from motility-related charge movement, increases as cell length decreases. This increasing non-linear charge density predicts a corresponding increase in sensor-motor density. However, while OHC lateral membrane particle density increases, a quantitative correspondence is absent. Thus, the presumed equivalence of particle and motor is questionable. The data more importantly indicate that whereas the voltage driving OHC motility, i.e. the receptor potential, may decrease with frequency due to the OHC's low-pass membrane filter, the electrical energy (Q x V) supplied to the lateral membrane will tend to remain stable. This conservation of energy delivery is likely crucial for the function of the cochlear amplifier at high frequencies.

Animals↗

PubMed1998

Adenovirus-mediated transfer of human acid maltase gene reduces glycogen accumulation in skeletal muscle of Japanese quail with acid maltase deficiency.

Acid maltase deficiency (AMD) causes a lysosomal glycogenosis inherited as an autosomal recessive trait. The infantile type of AMD (Pompe disease) leads to early death due to severe dysfunction of cardiac and respiratory muscles and no effective therapy is available. Replication-defective adenovirus vectors offer a promising tool for in vivo gene delivery and gene therapy. We constructed a recombinant adenovirus containing the human acid maltase (AM) cDNA downstream of the CAG promoter, composed of modified chicken beta-actin promoter and CMV IE enhancer (AxCANAM). Japanese quail with AMD was used for this study as an animal model for human AMD. When cultured fibroblasts from AMD quail were infected with AxCANAM, AM activity in the cells increased in proportion to the multiplicity of infection (MOI). When AxCANAM (4.5 x 10(8) PFU) was injected into unilateral superficial pectoral muscle of AMD quail, PAS staining showed that glycogenosomes disappeared and stainability of acid phosphatase was reduced in the injected area as compared with the contralateral muscle of the same birds. Biochemically, AM activity increased and glycogen content decreased in the injected muscle. Western blot analysis showed that AMD quail muscle injected with AxCANAM expressed human AM protein processed to active forms. These results suggest that the human AM cDNA transferred by an adenovirus vector was sufficiently expressed, leading to a marked reduction of the glycogen accumulation in the skeletal muscle of AMD quail.

Adenoviridae↗

PubMed1998

Cloning and characterization of kidney-specific promoter of human PTH/PTHrP receptor gene: absence of mutation in patients with pseudohypoparathyroidism type Ib.

Pseudohypoparathyroidism (PHP) is a heterogeneous disease complex characterized by resistance to parathyroid hormone (PTH). PHP type Ib has been thought to be caused by abnormalities in PTH/PTH-related protein (PTHrP) receptor. However, previous studies have shown no mutation in the coding region of PTH/PTHrP receptor gene in patients with PHP type Ib. Because patients with PHP type Ib do not have Albright's hereditary osteodystrophy, and because resistance to PTH is most prominent in proximal tubules of the kidney, PHP Ib may be caused by a kidney-specific abnormality in PTH/PTHrP receptor. Cloning of 5' region of human PTH/PTHrP receptor gene revealed that there are at least three untranslated exons, U1, U2 and U3. Exons U1 and U2 and the upstream promoter of exon U1 are used in kidney, but not in skin fibroblasts and osteoblastic cells. The upstream region of exon U1 was highly AT-rich and exhibited kidney-specific promoter activity. However, there was no mutation in these kidney-specific promoter regions and untranslated exons in eight patients with PHP type Ib. These results demonstrate that PHP type Ib is not caused by mutations in PTH/PTHrP receptor gene, at least in the examined patients. Identification and characterization of nuclear proteins that bind to kidney-specific promoter region of human PTH/PTHrP receptor may be necessary for the elucidation of pathogenesis of PHP type Ib.

5' Untranslated Regions↗

PubMed1998

Theoretical evidence of the existence of a diazafulvene intermediate in the reaction pathway of imidazoleglycerol phosphate dehydratase: design of a novel and potent heterocycle structure for the inhibitor on the basis of the electronic structure-activity relationship study.

The reaction mechanism of imidazoleglycerol phosphate dehydratase has not yet been clearly revealed. Structural comparison between inhibitors and the substrate IGP implicates that the reaction involves a diazafulvene intermediate. Here, we present evidence to support this hypothesis by investigating the electronic structure-enzyme inhibitory activity relationship on inhibitors with different heterocycles using 6-31G** level theory of the ab initio molecular orbital method. The calculation results showed that potent inhibitors can be distinguished from weak ones by the atomic charge density and by the energy levels of the highest occupied lone-pair orbital on the nitrogen atoms in the heterocycles. Furthermore, very good correlations (r2=0.8-0.9) were found between the charge density on the nitrogen atom and the inhibitory activity. It was also revealed that the diazafulvene is electronically similar to the potent inhibitors. Thus, these results strongly suggest the existence of the diazafulvene as an intermediate possessing tight-binding affinity to the enzyme. Based on the electronic structural similarity between the potent inhibitors and the proposed intermediate, a novel heterocycle was designed and predicted its inhibitory activity prior to the synthesis. Then, activity of synthesized inhibitors showed excellent agreement with this prediction. Hence, from the theoretical studies and experimental results, we conclude to obtain evidence of the hypothesis that the enzyme reaction proceeds via the diazafulvene intermediate.

Drug Design↗

PubMed1998

Monocyte chemoattractant protein-1 in the intervertebral disc. A histologic experimental model.

STUDY DESIGN: Monocyte chemoattractant protein-1 was investigated in an experimental rat model using immunohistochemistry. OBJECTIVE: To ascertain the precise mechanism of macrophage recruitment in the early phase of disc resorption. SUMMARY OF BACKGROUND DATA: In previous studies, many investigators reported that disc herniation was resorbed by monocytic phagocytosis. However, how the recruitment of monocytes was triggered is still unknown. METHODS: The autologous intervertebral discs from tails of Wistar rats were subcutaneously implanted into the abdomen. These discs were obtained on days 2, 3, 7, and 14 after implantation and were used for immunohistochemical study and for quantitative analysis of monocyte chemoattractant protein-1 by sandwich enzyme-linked immunosorbent assay. RESULTS: Monocyte chemoattractant protein-1-positive granulocytes and macrophages were observed surrounding the intervertebral disc, and monocyte chemoattractant protein-1-positive disc chondrocytes were observed in the nucleus pulposus and the inner anulus fibrosus on day 3. By day 7, monocyte chemoattractant protein-1-positive and TRPM-3-positive macrophages appeared in the granulation tissue, and some of these cells invaded the nucleus pulposus and inner anulus fibrosus. The concentration of monocyte chemoattractant protein-1 was highest on day 3. CONCLUSION: Intervertebral disc chondrocytes have chemotactic properties and play an active role in the recruitment of monocytes involved in disc resorption.

Animals↗

PubMed1998

Determination of alpha-amylase using 4-O-beta-D-galactopyranosylmaltotetraose (Gal-G4) as a substrate.

A new substrate, 4-O-beta-D-galactopyranosylmaltotetraose (Gal-G4) is applied for the determination of alpha-amylase in serum and urine in a coupled assay with alpha-glucosidase (EC 3.2.1.20), glucokinase (EC 2.7.1.2) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) as auxiliary enzymes. Gal-G4 having a 4-position of the non-reducing-end glucose residue modified by a beta-galactopyranose group is resistant for degradation by alpha-glucosidase as auxiliary enzyme. Moreover, this substrate is hydrolyzed at just one position by alpha-amylase in serum and urine. More than 99% of the products generated from Gal-G4 by alpha-amylase are identified 4-O-beta-D-galactopyranosylmaltose (Gal-G2), maltose, respectively. Glucose and maltose do not interfere the value of alpha-amylase activity at least up to 0.056 mmol/l (1 g/dl) glucose and 0.027 mmol/l (1 g/dl) maltose, respectively. We are now carrying out this work under the authority of The Enzyme committee of Japanese Society of Clinical Chemistry (JSCC) as a standard method for determination of alpha-amylase in clinical chemistry.

Carbohydrate Conformation↗

PubMed1998

A soft X-ray (80-1500 eV) grazing-incidence monochromator with varied-line-spacing plane gratings at PF-BL-11A.

The design and performance of a new soft X-ray beamline BL-11A at the Photon Factory (PF) are presented. A Hettrick-type grazing-incidence monochromator equipped with three varied-line-spacing plane gratings was designed and constructed at a bending-magnet source of the PF 2.5 GeV storage ring. An 800 lines mm(-1) laminar grating produced by aspheric-wavefront holographic recording optics, as well as a mechanically ruled blazed one, were tested. A resolving power of more than 4500 was achieved at 400 eV with either grating, and approximately 10(10) photons s(-1) are available at a resolving power of 2000. High photon flux enables low-concentration samples, such as surface adsorbates, to be studied. A simple scanning mechanism for a wide energy range is quite useful for EXAFS measurements on light elements such as C, N and O.

Journal Article↗

PubMed1998

A new image-plate reader for various sizes and shapes.

A new image-plate reader which can read image plates (IPs) having various sizes and shapes has been developed. The machine consists of a rotating laser head to induce luminescence photons from IPs and a porous cylindrical holder made of a composite of cast iron and porous ceramic - so-called 'breathnite'. Image plates can be fixed onto the inner surface of the cylindrical holder by evacuating the outer surface through a vacuum chamber with a mechanical pump. Image plates having various shapes and sizes up to 400 x 400 mm can be fixed without covering the open surface on the cylinder. In spite of such flexibility to various applications, the reader produces competitive performances compared with other commercial readers.

Journal Article↗

PubMed1998

Purification by ceftibuten-affinity chromatography and the functional reconstitution of oligopeptide transporter(s) in rat intestinal brush-border membrane.

The transport activity of ceftibuten, a dianionic peptide-like compound, was extracted from rat intestinal brush-border membrane by n-octylglucoside and reconstituted into asolectin liposomes by dialysis. The proteoliposomes prepared from the membrane extract showed an inward H+-gradient-dependent uptake of ceftibuten and glycylsarcosine. Ceftibuten-immobilized affinity chromatography of the membrane extract permitted the isolation of two polypeptides (apparent molecular mass of 117 and 127 kDa) that can recognize the dianionic peptide structure of ceftibuten. Proteoliposomes prepared from reconstituting the isolated proteins into asolectin vesicles showed an overshooting uptake of ceftibuten in the presence of an inwardly directed H+ gradient, and this uptake could be inhibited by L-valyl-L-proline. N-glycanase digestion of the isolated proteins, 117 and 127 kDa, trimmed them into 78 and 120 kDa products, respectively. The protein core size of the smaller protein was in agreement with the calculated molecular mass of approximately 79 kDa for the rat PepT1 transporter obtained by other investigators.

Animals↗

PubMed1998

Novel antipsychotic agents with dopamine autoreceptor agonist properties: synthesis and pharmacology of 7-[4-(4-phenyl-1-piperazinyl)butoxy]-3,4-dihydro-2(1H)-quinolinone derivatives.

To develop a novel antipsychotic agent which is an agonist of dopamine (DA) autoreceptors and an antagonist of postsynaptic DA receptors, a series of 7-[4-[4-(substituted phenyl)-1-piperazinyl]butoxy]-3,4-dihydro-2 (1H)-quinolinones was synthesized and their dual activities were examined. The postsynaptic DA receptor antagonistic activities of the compounds were evaluated by their ability to inhibit stereotypy induced by apomorphine in mice, and the autoreceptor agonist activities were determined by their effects on the gamma-butyrolactone (GBL)-induced increase in L-dihydroxyphenylalanine (DOPA) synthesis in the mouse brain. Many compounds inhibited the stereotypic behavior, and several compounds reversed the GBL-induced increase in the DOPA synthesis. Among them, 7-[4-[4-(2,3-dichlorophenyl)-1-piperazinyl]-butoxy]-3,4-dihydro-2 (1H)-quinolinone (28, aripiprazole, OPC-14597) was found to have these two activities. This compound reversed the GBL-induced DOPA synthesis (ED50 values of 5.1 mumol/kg p.o.) and inhibited the APO induced stereotypy (ED50 values of 0.6 mumol/kg p.o.). Compound 28 induced catalepsy at 10 times higher dose than that required for the antagonism of APO-induced stereotypy (ED50 value of 7.8 mumol/kg p.o.).

4-Butyrolactone↗

PubMed1998

Clinical and metabolic correction of pompe disease by enzyme therapy in acid maltase-deficient quail.

Pompe disease is a fatal genetic muscle disorder caused by a deficiency of acid alpha-glucosidase (GAA), a glycogen degrading lysosomal enzyme. GAA-deficient (AMD) Japanese quails exhibit progressive myopathy and cannot lift their wings, fly, or right themselves from the supine position (flip test). Six 4-wk-old acid maltase-deficient quails, with the clinical symptoms listed, were intravenously injected with 14 or 4.2 mg/kg of precursor form of recombinant human GAA or buffer alone every 2-3 d for 18 d (seven injections). On day 18, both high dose-treated birds (14 mg/kg) scored positive flip tests and flapped their wings, and one bird flew up more than 100 cm. GAA activity increased in most of the tissues examined. In heart and liver, glycogen levels dropped to normal and histopathology was normal. In pectoralis muscle, morphology was essentially normal, except for increased glycogen granules. In sharp contrast, sham-treated quail muscle had markedly increased glycogen granules, multi-vesicular autophagosomes, and inter- and intrafascicular fatty infiltrations. Low dose-treated birds (4.2 mg/kg) improved less biochemically and histopathologically than high dose birds, indicating a dose-dependent response. Additional experiment with intermediate doses and extended treatment (four birds, 5.7-9 mg/kg for 45 d) halted the progression of the disease. Our data is the first to show that an exogenous protein can target to muscle and produce muscle improvement. These data also suggest enzyme replacement with recombinant human GAA is a promising therapy for human Pompe disease.

Animals↗

PubMed1998

Purification and liposomal reconstitution of the oligopeptide transport activity in rat renal cortex using ceftibuten-affinity chromatography.

The carrier protein(s) responsible for the transport of ceftibuten, a peptide-like dianionic cefem, in rat renal brush-border membrane were solubilized and purified by a ceftibuten-ligand specific affinity chromatography technique. The proteoliposomes reconstituted from the solubilized brush-border membrane proteins by dialysis had H+-sensitive uptake of ceftibuten and trans-stimulative effect by cephalexin. A specific uptake activity for ceftibuten was found in the 3.5 M-eluted fraction but not the flowthrough and the 0.5 M-eluted fraction of the affinity chromatography. Analyzing this active fraction by SDS/PAGE after reconstituting into liposomes gave two major proteins (approx. molecular masses of 130 and 107 kDa). The purification protocol presented in this study permitted an efficient isolation of the carrier proteins responsible for the transport of ceftibuten and other peptide-like compounds.

Animals↗

PubMed1998

Multigeneration exposure test of Drosophila melanogaster to ELF magnetic fields.

Mutations, other than dominant lethals, were accumulated on wild type second chromosomes (+) of Drosophila melanogaster during exposure to 50 Hz sinusoidal alternating magnetic fields of 0.5 or 5 mT (rms) for 40 generations by the Curly/Plum(Cy/Pm) accumulation method. We maintained, for 40 generations under continuous exposure, each (+) chromosome as a heterozygote with (Cy) chromosome. Viability of the (+) chromosome was tested by sib-mating of (Cy/+) male and (Cy/+) female in a culture every 10th generation to obtain the homozygote. Viability indices, defined as twice the ratio of number of (+/+) flies to that of (Cy/+) flies plus 1 in the progeny of the test mating, also were calculated, which equaled 1.00 at the starting point. For the control and 0.5 and 5 mT exposed groups, percent frequencies of recessive lethal lines, defined as a line with (+/+) flies less than 0.3% in the test mating, were, respectively, 1.9, 0.9, and 2.9% (10th), 9.0, 4.9, and 9.5% (20th), 30.3, 22.9, and 30.4% (30th), and 39.9, 32.4, and 43.3% (40th generation). For the control and 0.5 and 5 mT groups, average viability indices, excluding lethals and markedly deleterious, were, respectively, 0.778, 0.796, and 0.752 (20th), 0.704, 0.698, and 0.694 (30th), and 0.669, 0.678, and 0.595 (40th generation). Their decreasing rates were 0.0054, 0.0059, and 0.0078 per generation. No significant difference was detected among the exposure levels in either the recessive lethal mutation frequency or the viability index.

Animals↗

PubMed1998

Cloning, high level-expression and characterization of human lens thioltransferase.

Polymerase chain reaction (PCR) primers, directed against the nucleotide sequence of pig liver thioltransferase (PLTT) were used to amplify human lens thioltransferase (HLTT) from a pool of human lens cDNA. The 520 bp PCR fragment obtained was cloned unidirectionally into pCR 3.1-Uni vector and sequenced. The cDNA sequence of the lens thioltransferase had 98% and 87% homology to pig liver and human placental thioltransferases (TTase) respectively. Nhe1 and EcoR1 fragment of the recombinant PCR 3.1-Uni vector was subcloned in pET 23a Expression vector. High level expression of HLTT was accomplished in Escherichia coli and the expressed protein was characterized by immunoblot analysis with anti PLTT and N-terminal amino acid sequence analysis. The recombinant enzyme efficiently dethiolated protein thiol mixed disulfides conjugated to both cystine (PSSC) and glutathione (PSSG) and had a significant dehydroascorbate reductase activity. Human lens thioltransferase thus displayed structural and functional characteristics identical to pig liver and human placental thioltransferases.

Amino Acid Sequence↗

PubMed1998

Antioxidant, OPC-14117, attenuates edema formation, and subsequent tissue damage following cortical contusion in rats.

Oxygen free radicals contribute to various kinds of tissue injury processes within the central nervous system. It has been suggested that inhibition of free radical formation has the potential to attenuate secondary neural tissue damage involving ischemia or trauma, and antioxidant therapy may offer a promising approach. In the present study, employing a cortical contusion model in the rat, contusion-induced neural damage, was evaluated by investigating edema formation, behavioral activities and histological changes. The effects of the superoxide radical scavenger, OPC-14117, were also tested to determine how free radicals may contribute to such neural damage. The results demonstrated that cerebral contusion induces a progressive decrease in tissue specific gravity representing edema formation, and behavioral deficits in the Morris water maze test and habituation of exploratory activity. Histological examinations revealed necrotic cavity formation in the cortex and selective neuronal death of the hippocampal CA3 region. These changes were significantly attenuated by OPC-14117, which was administered as a single dose immediately following trauma induction. The above results indicate that oxygen free radicals are involved in contusion-induced edema formation, subsequent tissue damage and cognitive deficits. The superoxide radical scavenger, OPC-14117, has a powerful therapeutic potential for preventing secondary cell damage following traumatic brain injury.

Animals↗

PubMed1998

Fiber-type-dependent expression of adenovirus-mediated transgene in mouse skeletal muscle fibers.

We show the efficient transduction and expression of the lacZ gene in the skeletal muscle of adult C57BL/10ScSn mice after adenovirus-mediated gene transfer. Of the myofibers in the tibialis anterior muscle 62% were beta-galactosidase positive after injection of the lacZ gene under the control of the chicken beta-actin promoter and the cytomegalovirus enhancer. The transduced gene was preferentially expressed in type IIA and IIX fibers, which were richer in oxidative enzymes than type IIB fibers.

Actins↗

PubMed1998

Characterization of the cells in the repair tissue of full-thickness articular cartilage defects.

It is well established that a full-thickness articular cartilage defect is repaired with a fibrocartilaginous tissue, cells of which are derived from undifferentiated mesenchymal stem cells in the bone marrow. To characterize the repair cells biochemically, full-thickness defects were created in rabbit knee joints and the repair tissues taken at 3, 6, and 12 weeks after surgery. The repair cells were cultured and examined biochemically to investigate the effects of four exogenous growth factors with regard to the metabolism of type II collagen and proteoglycans. A significant increase of carboxy-terminal type II procollagen peptide production was observed in the conditional medium of the repair cells, especially taken at 6 weeks after surgery, in the presence of each growth factor. Glycosaminoglycan content was also increased and proteoglycan synthesis stimulated. The repair cells taken at the early stage of the repair process could originally have more activity of type II collagen synthesis, and the growth factors used could enhance the differentiation of the repair cells in vitro.

Animals↗