Search PubMed⌕ Search

Biomedical subjects

T Noguchi

Publications and source records attributed to T Noguchi.

At least 433 records · Page 24Linked to original sources
PubMed1995

A new saxitoxin analogue from a xanthid crab Atergatis floridus.

A novel paralytic toxin was isolated from toxic specimens of a xanthid crab Atergatis floridus inhabiting the Pacific coast of Shikoku Island. Its structure was deduced to be 11-saxitoxinethanoic acid (SEA) based on high-performance liquid chromatography, electrospray ionization mass spectrometry, and 1H and 13C-NMR spectrometries. This acid was assumed to exist as an equilibrium mixture of three tautomers, the main tautomer being the hydrate form 11 beta-epimer. SEA showed a specific toxicity of 830 mouse units per mumole on i.p. injection into mice.

Acetic Acid↗
PubMed1995

The development of neural visinin-like Ca(2+)-binding protein 2 immunoreactivity in the rat neocortex and hippocampus.

Neural visinin-like Ca(2+)-binding protein 2 (NVP2) immunoreactivity in the rat neocortex and hippocampus was barely detectable by immunoblot analysis on postnatal day 1 (P1), but increased during postnatal weeks 2-3, reaching a plateau on P28. Immunohistochemical analysis revealed moderate immunoreactivity firstly on P7 in some subsets of the hippocampal interneurons and in the hippocampal pyramidal cells and dentate granule cells. Immunoreactivity of the interneurons decreased during postnatal weeks 2-3 and disappeared by P28. In contrast, immunoreactivity of the cortical and hippocampal pyramidal cells and dentate granule cells abruptly increased during postnatal week 2. The distinctly immunoreactive cells were distributed throughout the neocortex, especially in the cortical plate, and the stratum pyramidale of Ammon's horn and granular layer of the dentate gyrus on P14. Immunoreactivity was homogeneously concentrated in the cell bodies and proximal dendrites at this stage, whereas thereafter immunoreactivity in the neuropil gradually increased, and underwent a relative decrease in the cell bodies. By P28, the higher and granular immunoreactivity in the neuropil covered whole layers of the neocortex, Ammon's horn and the dentate gyrus, the same as in adults. Differential expression of NVP2 in different neuron populations may reflect the differential functional consequences for neuronal development.

Animals↗
PubMed1995

Microflora and tetrodotoxin-producing bacteria in a gastropod, Niotha clathrata.

Shellfish (Niotha clathrata) were collected in both July and November from three locations in Taiwan (Pingtung, Kaohsiung and Chiai Prefecture) and assayed for anatomical distribution of tetrodotoxin (TTX) and aerobic heterotrophic bacteria. Pingtung specimens showed higher toxicity than those from Kaohsiung and Chiai, and did not show much seasonal variation. At each site, the total aerobic bacterial counts in November samples were higher than in July. The predominant genera were Vibrio, Pseudomonas, Pasteurella, Aeromonas and Plesiomonas. Vibrio comprised more than 35% of the genera, with V. alginolyticus as the major species. The viable counts of Vibrio species were higher in November than in July. However, the results did not suggest any relationship between the total count or viable count and the toxicity of the shellfish. HPLC, UV and gas chromatographic-mass spectrometric analyses demonstrated that some of the bacteria isolated, such as V. alginolyticus, V. parahaemolyticus, Pseudomonas spp. Plesiomonas sp. and Aeromonas sp., produced TTX and/or related substances.

Animals↗
PubMed1995

Effects of insulin-like growth factor-I, estrogen, glucocorticoid, and transferrin on the mRNA contents of ovalbumin and conalbumin in primary cultures of quail (Coturnix coturnix japonica) oviduct cells.

The effects of estrogen, dexamethasone, insulin-like growth factor-I (IGF-I), and transferrin on the messenger RNA (mRNA) contents of ovalbumin and conalbumin in primary cultures of quail oviduct cells were investigated. In the absence of one of the above hormones or factors, a decrease in ovalbumin mRNA was prominent. In particular, removal of IGF-I and transferrin caused a significant effect. Studies using a combination of estrogen, dexamethasone, IGF-I and transferrin indicated that IGF-I cooperates with estrogen or dexamethasone and transferrin works with dexamethasone. Specifically, IGF-I enhanced ovalbumin synthesis or increased cellular ovalbumin mRNA content depending on its concentration in the medium in the presence of estrogen. However, the effects of estrogen, dexamethasone, IGF-I, and transferrin were not similarly observed with conalbumin mRNA. These results show that ovalbumin synthesis is controlled by estrogen or glucocorticoid with IGF-I or transferrin and that cellular ovalbumin mRNA content is also regulated by these hormones or transferrin. In contrast, conalbumin synthesis and cellular content of conalbumin mRNA are not affected by these hormones under the conditions of the present study.

Animals↗
PubMed1995

Metabolism of clomipramine in a Japanese psychiatric population: hydroxylation, desmethylation, and glucuronidation.

We measured the concentrations of clomipramine and its metabolites, N-desmethylclomipramine, 8-hydroxy-N-desmethylclomipramine, 8-hydroxyclomipramine by high-performance liquid chromatography in 108 Japanese psychiatric patients receiving clomipramine hydrochloride PO. The concentrations of the glucuronide conjugates of 8-hydroxyclomipramine and 8-hydroxy-N-desmethylclomipramine were assayed via enzymatic hydrolysis. Although there were large interindividual variations of concentrations of parent, intermediate metabolic compounds, and glucuronide conjugates, significant positive correlations were observed between these drug concentrations and daily doses of clomipramine hydrochloride (mg/kg body weight). Although the metabolic ratios for desmethylation, hydroxylation, and glucuronidation that were calculated from steady-state drug concentrations varied substantially with 36-, 14-, and 28-fold interindividual variations, respectively, apparent poor desmethylators, poor hydroxylators, or poor glucuronidators were not found.

Adolescent↗
PubMed1995

Activation of Na(+)-H+ antiporter (NHE-1) gene expression during growth, hypertrophy and proliferation of the rabbit cardiovascular system.

The Na(+)-H+ antiporter is a unique transmembrane protein with multiple roles in cellular functions through intracellular alkalization. It participates in the regulation of intracellular pH, cell volume and intracellular signalling in response to various mitogenic stimuli. To clarify its role as a subcellular signal in cardiovascular remodeling like vascular hyperplasia or cardiac hypertrophy, we determined mRNA levels of the Na(+)-H+ antiporter isoform, NHE-1, in vascular smooth muscles and pressure-overloaded hearts in rabbits. The NHE-1 mRNA levels in rabbit aortas and hearts were developmentally regulated with high levels at embryonic and neonatal stages than in adults. In primary-cultured smooth muscle cells (SMC), the mRNA levels were increased during exponential growth, but decreased to initial levels at confluency. Growth of a mutant SMC line, C5, which is deficient in Na(+)-H+ antiporter activity, was markedly reduced in bicarbonate-free medium. However, when the activity was restored by transfecting cells with a full-length NHE-1 cDNA in an expression vector, the growth rate of C5 was accelerated again. After balloon injury to the vascular wall, the NHE-1 mRNA levels of the injured arteries were also increased, suggesting that Na(+)-H+ antiporter contributes to the network of the growth promoting systems in smooth muscle cells in vivo. Pressure-overload on the ventricle increased the NHE-1 mRNA levels in hearts approximately two-fold of sham-operated rabbits after 3 days and remained for at least two weeks (P < 0.05). We further demonstrated that 3-methylsulfonyl-4-piperidino-benzoyl guanidine mesylate (Hoe 694), a potent antagonist of Na(+)-H+ antiporter, partially inhibited stretch-induced activation of mitogen-activated kinase (MAP kinase) in the cultured cardiomyocytes. From these results, we conclude that activation of the Na(+)-H+ antiporter and its gene expression is involved in molecular mechanisms of both cardiac hypertrophy and vascular smooth muscle cell proliferation, indicating a potential target in developing new therapeutics for cardiovascular diseases.

Aging↗
PubMed1995

Recurrent cervical abscess due to piriform sinus fistula.

A case of recurrent abscess on the left anterior neck due to a left piriform sinus fistula is presented. It is known that a piriform sinus fistula may cause acute suppurative thyroiditis, and also that it induces the recurrent anterior cervical abscess described in this case. Here, we suggest that barium swallow is an important aid to diagnosis cases of recurrent cervical abscess.

Abscess↗
PubMed1995

Diet differentially regulates glucokinase and L-type pyruvate kinase gene expression in rat liver.

The regulation of gene expression of glucokinase (GK) and L-type pyruvate kinase (L-PK) in rat liver was investigated and compared with the previously reported regulation of lipogenic enzymes. Experiments were conducted in which the time courses and responses to diet quantity of mRNA concentrations and enzyme activities after refeeding a carbohydrate/protein diet (CP) to food-deprived rats were measured. The effects of dietary nutrients on the gene expression were investigated in rats refed either the CP diet, a carbohydrate diet without protein (C), a protein diet without carbohydrate (P), or a carbohydrate/protein/corn oil diet (CPF). The effects of the CPF diet on the gene expression after insulin treatment to diabetic rats were also investigated. After refeeding the CP diet, GK mRNA concentration and enzyme activity reached maximum levels in 2 h and 16-24 h, respectively, whereas those of L-PK peaked in 16 h and 48 h, respectively, similar timecourse to lipogenic enzymes. Moreover, GK mRNA concentrations were maximal in rats fed 20% of the ad libitum diet intake, and L-PK mRNA concentrations, like lipogenic enzyme mRNA, were maximal in rats fed approximately 50% of ad libitum intake. GK mRNA concentrations were significantly increased in parallel with an increase in plasma insulin and glucose concentrations. GK and L-PK mRNA and enzyme levels in rats fed the C diet were comparably induced to the levels in those fed the CP diet. L-PK mRNA induction by the CP diet was significantly reduced by dietary polyunsaturated fatty acids (CPF diet), whereas the GK mRNA induction was not significantly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Identification of Fourier transform infrared signals from the non-heme iron in photosystem II.

Fourier transfer infrared (FTIR) signals originating from a high-potential electron acceptor in PS II were studied by flash-induced FTIR difference spectroscopy. Redox titration of these signals using ferri-ferrocyanide mixtures showed midpoint potentials (Em) of 489 +/- 12 and 426 +/- 9 mV at pH 5.5 and 6.5, respectively, revealing a pH dependence of about -60 mV/pH unit. These Em values and pH dependence were in good agreement with those of the non-heme iron, so-called Q400, located between QA and QB. This indicates that the observed FTIR signals are due to changes in ligands of the non-heme iron and surrounding protein moieties induced on photoreduction from Fe3+ to Fe2+.

Electron Transport↗
PubMed1995

Case report: inhalation therapy of paromomycin is effective for respiratory infection and hypoxia by cryptosporidium with AIDS.

A 24-year-old man with AIDS and hemophilia A had intractable diarrhea and fever. Upon examination of stool and of a sigmoidal biopsy specimen, cryptosporidium was revealed. Approximately 2 months after admission, respiratory infection with hypoxia due to cryptosporidium developed. Paromomycin inhalation was effective therapy. To the authors' knowledge, this is the first case of respiratory cryptosporidiosis treated successfully by paromomycin inhalation.

AIDS-Related Opportunistic Infections↗
PubMed1995

Interindividual variations of desmethylation and hydroxylation of amitriptyline in a Japanese psychiatric population.

We measured the concentrations in plasma of amitriptyline and its metabolites, nortriptyline and geometric isomers of 10-hydroxynortriptyline and 10-hydroxyamitriptyline, in 73 Japanese psychiatric patients receiving amitriptyline hydrochloride (Tryptanol; Banyu Pharmaceutical Co. Ltd., Tokyo, Japan) by high-performance liquid chromatography. Although there were large interindividual variations of total drug concentrations and concentrations of parent or intermediate metabolic compounds in plasma, significant positive correlations were observed between these drug concentrations and daily doses of amitriptyline hydrochloride (milligrams per kilogram of body weight). The metabolic ratios for both hydroxylation and desmethylation varied substantially with approximately 8- to 19-fold interindividual variations. Frequency distribution histograms and probit analyses of these parameters identified neither definite poor hydroxylators nor poor desmethylators of amitriptyline.

Adult↗
PubMed1995

Role of prostaglandin in the formation of osteoclasts induced by capsular-like polysaccharide antigen of Actinobacillus actinomycetemcomitans strain Y4.

We found no reports that capsular-like polysaccharide antigen purified from Actinobacillus actinomycetemcomitans either induces osteoclastic bone resorption in mouse organ cultures or promotes osteoclast formation in mouse marrow cultures. In contrast, capsular-like polysaccharide antigen purified from A. actinomycetemcomitans strain Y4 induced bone resorption in mouse organ culture. To examine the mechanism of bone resorption induced by A. actinomycetemcomitans, mouse bone marrow cells were cultured with A. actinomycetemcomitans strain Y4 capsular-like polysaccharide antigen. A. actinomycetemcomitans strain Y4 capsular-like polysaccharide antigen stimulated osteoclast-like cell formation in mouse bone marrow cultures. However, the polysaccharide of A. actinomycetemcomitans lipopolysaccharide did not induce the formation of osteoclast-like cells. Indomethacin inhibited osteoclast-like cell formation mediated by A. actinomycetemcomitans strain Y4 capsular-like polysaccharide antigen in a dose-dependent manner. There was a good correlation between the number of osteoclast-like cells formed in the marrow culture and the amount of prostaglandin E2 released into the culture media. When mouse bone marrow cells were cultured with prostaglandin E2 during the culture periods, many osteoclast-like cells were formed. These results indicate that prostaglandin E2 is involved in the mechanism of the formation of osteoclast-like cells mediated by A. actinomycetemcomitans strain Y4 capsular-like polysaccharide antigen. A. actinomycetemcomitans strain Y4 capsular-like polysaccharide antigen may play an important role in inflammatory bone resorption by promoting osteoclast formation in periodontal disease.

Acid Phosphatase↗
PubMed1995

Actinobacillus actinomycetemcomitans Y4 capsular-polysaccharide-like polysaccharide promotes osteoclast-like cell formation by interleukin-1 alpha production in mouse marrow cultures.

The mechanism of osteoclast-like cell formation induced by periodontopathic bacterium Actinobacillus actinomycetemcomitans Y4 (serotype b) capsular-polysaccharide-like polysaccharide (capsular-like polysaccharide) was examined in a mouse bone marrow culture system. When mouse bone marrow cells were cultured with A. actinomycetemcomitans Y4 capsular-like polysaccharide for 9 days, many multinucleated cells were formed. The multinucleated cells showed several characteristics of osteoclasts, including tartrate-resistant acid phosphatase (TRACP) and the ability to resorb the calcified dentine. In this study, we examined the effects of antisera to interleukins on the formation of osteoclast-like cells induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide. Monospecific anti-mouse recombinant interleukin-1 alpha (rIL-1 alpha) serum completely inhibited the formation of osteoclast-like cells in the presence of A. actinomycetemcomitans Y4 capsular-like polysaccharide. However, anti-mouse rIL-1 beta and anti-mouse rIL-6 sera showed no effect on osteoclast-like cell formation. IL-1 receptor antagonist significantly inhibited the osteoclast-like cell formation mediated by A. actinomycetemcomitans Y4 capsular-like polysaccharide in mouse marrow cultures. The bioactive IL-1 was detected in the culture media of mouse bone marrow cells stimulated with A. actinomycetemcomitans Y4 capsular-like polysaccharide. These results indicate that IL-1 alpha is involved in the mechanism of the formation of osteoclast-like cells induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide. We sought to determine whether osteoclast-like cell formation induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide could be modulated by the protein kinase inhibitors H8 and HA1004. The formation of osteoclast-like cells was suppressed by H8 and HA1004. These findings suggest that the signals by protein kinases may regulate osteoclast-like cell formation induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide. Furthermore, a correlation between IL-1 alpha and prostaglandin E2 in the osteoclast recruitment induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide is discussed.

Acid Phosphatase↗
PubMed1995

Expression of transmembrane-type protein tyrosine phosphatase mRNA along rat nephron segments.

Protein phosphorylation on tyrosine residues is one of the main cell signaling mechanisms. Cellular phosphotyrosyl levels are regulated by the activities of protein tyrosine kinases (PTK) and protein tyrosine phosphatases (PTPase). We have previously reported cDNA cloning of several types of PTPase from rat kidney, including LRP (leukocyte common antigen-related protein; also known as the transmembrane-type tyrosine phosphatase, i.e., RPTP alpha). LRP mRNA was shown to be abundant in the kidney; however, our understanding of the functional role of LRP in the kidney is very limited. To gain keener insight into the function of LRP in the kidney, our first approach was to reveal its mRNA distribution along rat nephron segments. Large signals were found in inner medulla by Northern blot analysis. By using a reverse transcription and polymerase chain reaction assay of individual microdissected tubule segments along the nephron [proximal convoluted tubule (PCT), medullary thick ascending limb (MTAL), cortical collecting duct (CCD), outer medullary collecting duct (OMCD), and inner medullary collecting duct (IMCD)] and glomeruli, we revealed intrarenal localization of LRP mRNA. LRP mRNA was detected in all nephron segments tested but was relatively rich in the IMCD. Rank order of the signal intensity was IMCD > PCT = OMCD > CCD > MTAL = glomeruli. Immunohistochemistry also revealed that LRP was abundant in IMCD. This pattern of expression gives rise to an interesting possibility that LRP might be involved in the specific renal tubule function, such as urinary concentrating mechanism; however, further study is required to describe the function of LRP in more detail.

Amino Acid Sequence↗
PubMed1995

Salt-sensitive hypertension in transgenic mice overexpressing Na(+)-proton exchanger.

Essential hypertension is one of the most common diseases that exacerbate the risk of cardiovascular or cerebrovascular attacks. Although the etiology of essential hypertension remains unclear, recent investigations have revealed that an enhancement of Na(+)-proton (Na(+)-H+) exchange activity is a frequently observed ion transport abnormality in hypertensive patients and animal models. To test the hypothesis that increased Na(+)-H+ exchange causes hypertension, we produced transgenic mice overexpressing Na(+)-H+ exchanger and analyzed their Na+ metabolism and blood pressure. Urinary excretion of water and Na+ was significantly decreased in transgenic mice, and systolic blood pressure was elevated after salt loading. The impaired urinary excretion of Na+ suggested that the Na(+)-H+ exchanger overexpressed in the renal tubules increased reabsorption of Na+, which caused a blood pressure elevation by Na+ retention after excessive salt intake. Our results demonstrate that overexpression of Na(+)-H+ exchanger can be a genetic factor that interacts with excessive salt intake and causes salt-sensitive blood pressure elevation.

Animals↗
PubMed1995

A new drug delivery system using plasma-irradiated pharmaceutical aids. V. Controlled release of theophylline from plasma-irradiated double-compressed tablet composed of a wall material containing polybenzylmethacrylate.

A controlled-release tablet was obtained by oxygen plasma irradiation on the outer layer of double-compressed tablets prepared from theophylline as a core material and a copolymer of methylmethacrylate (MMA) and benzylmethacrylate (BzMA) as a single wall material, making this possible that polybenzylmethacrylate (PBzMA) has dual intramolecular functions, a plasma degradable main chain and a plasma-cross-linkable benzyl group in the side chain as an effect of plasma irradiation. It was shown that the dissolution profiles can be varied so as to cause release of theophylline at different rates, depending on the set of conditions chosen for tablet manufacture and for plasma operation.

Bronchodilator Agents↗
PubMed1995

Stability of a 1 beta-methylcarbapenem antibiotic, meropenem (SM-7338) in aqueous solution.

The stability and the degradation products of 1 beta-methylcarbapenem, meropenem in aqueous solution were investigated. In pH 4-8 dilute solution, pseudo-first-order degradation was observed, and good stability of meropenem in aqueous solution was demonstrated by the effect of 1 beta-methyl group against hydrolysis of beta-lactam ring. As degradation products, the beta-lactam hydrolyzed product and the dimer product resulting from intermolecular aminolysis of beta-lactam ring by the amine of the second molecule were described.

Anti-Infective Agents↗