Biomedical subjects

A Takeuchi

Publications and source records attributed to A Takeuchi.

At least 91 records · Page 5Linked to original sources

PubMed1997

In vitro and in vivo expression of inducible nitric oxide synthase during experimental endotoxemia: involvement of other cytokines.

In this study, we investigated the expression of genes for inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6) of Kupffer cells in the presence of lipopolysaccharide (LPS), and the tissue expression of iNOS in a rat liver after LPS injection at various time intervals. The effects of L-NG-nitroarginine-methyl-esther HCI (L-NAME), a NO inhibitor, also were examined. The mRNA transcripts of TNF-alpha, IL-1 beta, and IL-6 were rapidly detected no more than at 1 h after LPS stimulation, whereas the iNOS transcript was detectable from 3 h after LPS stimulation and maximally increased at 12 h. This fact suggested that these early induced cytokines were related to expression of iNOS. Using an anti-iNOS antiserum raised against recombinant iNOS protein, immunohistochemical analysis was made to reveal kinetics of NO producing cells. The cells immunoreactive for iNOS appeared at 6 h post-LPS injection in the sinusoids of the liver. By structural and immunohistochemical studies, almost all iNOS positive cells were identified as Kupffer cells and endothelial cells. The number of cells immunoreactive for iNOS increased until 12 h post-LPS injection. At 24 h after LPS injection, iNOS positive cells were restricted to the foci of spotty necrosis. Hepatic injury measured by released enzymes was increased by pretreatment of L-NAME before LPS injection.

Animals↗

PubMed1997

Simplified method for the determination of 25-hydroxy and 1alpha,25-dihydroxy metabolites of vitamins D2 and D3 in human plasma. Application to nutritional studies.

A simplified method for the determination of 25-hydroxy and 1alpha,25-dihydroxy metabolites of vitamins D2 and D3 in human plasma was developed. Plasma samples were deproteinizated and applied to a Bond Elut C18OH cartridge to separate 25-hydroxyvitamin D (25-OH-D) and 1alpha,25-dihydroxyvitamin D [1,25(OH)2D] fractions. The 25-OH-D fraction was purified by a Bond Elut C18 cartridge and 25-OH-D2 and 25-OH-D3 were assayed by HPLC using a Zorbax SIL column. The 1,25(OH)2D fraction obtained above was subsequently applied to HPLC using a Zorbax SIL column to separate 1,25(OH)2D2 and 1,25(OH)2D3 fractions which were determined by a radioreceptor assay (RRA) using calf thymus receptor. The method was applied to nutritional studies.

25-Hydroxyvitamin D 2↗

PubMed1997

Hard X-ray microbeam experiment at the Tristan main ring test beamline of the KEK.

A hard X-ray microbeam with zone-plate optics has been tested at the MR-BW-TL beamline on the Tristan main ring of the KEK, and preliminary experiments on scanning microscopy have also been performed. A sputtered-sliced Fresnel zone plate with an Au core and Ag/C multilayer is used as an X-ray focusing device. The outermost zone width of the zone plate is 0.25 microm. A focused spot size of approximately 0.5 mum has been achieved at an X-ray energy of 8.54 keV. In a scanning X-ray microscopy experiment, test patterns with submicrometer fine structure have been clearly resolved.

Journal Article↗

PubMed1997

Cloning and characterization of a transcription factor that binds to the proximal promoters of the two mouse type I collagen genes.

We have used the yeast one-hybrid system to clone transcription factors that bind to specific sequences in the proximal promoters of the type I collagen genes. We utilized as bait the sequence between -180 and -136 in the pro-alpha2(I) collagen promoter because it acts as a functional promoter element and binds several DNA-binding proteins. Three cDNA clones were isolated that encoded portions of the mouse SPR2 transcription factor, whereas a fourth cDNA contained a potential open reading frame for a polypeptide of 775 amino acids and was designated BFCOL1. Recombinant BFCOL1 was shown to bind to the -180 to -152 segment of the mouse pro-alpha2(I) collagen proximal promoter and to two discrete sites in the proximal promoter of the mouse pro-alpha1(I) gene. The N-terminal portion of BFCOL1 contains its DNA-binding domain. DNA transfection experiments using fusion polypeptides with the yeast GAL4 DNA-binding segment indicated that the C-terminal part of BFCOL1 contained a potential transcriptional activation domain. We speculate that BFCOL1 participates in the transcriptional control of the two type I collagen genes.

Amino Acid Sequence↗

PubMed1997

Glomerular proliferating cell kinetics in acute post-streptococcal glomerulonephritis (APSGN).

To investigate the time sequence of glomerular cell proliferation in acute human glomerulonephritis, renal biopsy tissues were examined from 15 acute post-streptococcal glomerulonephritis (APSGN) patients (who were biopsied 1-31 days after onset), using an immunoperoxidase technique with monoclonal antibodies against proliferating cell nuclear antigen (PCNA) and various cell surface markers. Few, if any, PCNA+ cells were observed in normal glomeruli, but many cells were positive for PCNA in the acute phase of APSGN. Glomerular PCNA+ cells were observed either within glomerular tufts, or lining Bowman's capsule (parietal epithelial cells); the number of positive cells tended to decrease exponentially as the disease duration increased (r = -0.91, P < 0.0001). PCNA+ cells within glomerular tufts were further identified by double immunostaining. PCNA was not found in PMN or T cells, but a small proportion of macrophages were PCNA+. Most of the remaining PCNA+ cells were resident glomerular cells; the proportion of PCNA+ endothelial cells (CD31+) was over 80 per cent in the early phase, but as the disease continued the proportion of mesangial cells (alpha-smooth muscle actin+) increased to about half of the total PCNA+ cells within the tuft. These data indicate that the hypercellular glomeruli in APSGN are due not only to immune cell infiltration, but also to resident glomerular cell proliferation, probably induced by locally produced growth factors.

Acute Disease↗

PubMed1997

Cerebrospinal fluid interleukin-6 in progressive Neuro-Behçet's syndrome.

Central nervous system (CNS) involvement in Behçet's disease, usually called neuro-Behçet's syndrome (NB), is one of the most serious complications of the disease. The present study examined cerebrospinal fluid (CSF) interleukin-6 (IL-6) activity in patients with NB to explore its relevance to the progressive CNS disease. Paired CSF and serum specimens were obtained from 11 patients who were diagnosed as having progressive NB based on careful clinical observation and from 11 patients with active Behçet's disease but lacking progressive CNS disease. IL-6 levels in the CSF and sera were determined using IL-6-dependent murine hybridoma MH60.BSF2 cells. All 11 patients with progressive NB showed marked elevation of CSF IL-6 activity [0.18-3.90 U/ml, 1.19 +/- 1.18 (mean +/- SD), normal range, <0.010 U/ml]. In contrast, only 5 of the 11 control patients showed very modest CSF IL-6 activity below 0.10 U/ml, and CSF IL-6 was not detected in the other 6 patients. There was no difference in the serum IL-6 activities of patients with progressive NB and control patients. There was no significant correlation of CSF IL-6 activity with serum IL-6 activity, CSF cell counts, CSF total protein levels, or the CSF/serum albumin quotient. These results indicate that persistent chronic CNS inflammation, as evidenced by the enhanced production of IL-6 within the CNS, plays an important role in the pathogenesis of progressive neuropsychiatric manifestations in Behcet's disease.

Adult↗

PubMed1997

Saccharated ferric oxide (SFO)-induced osteomalacia: in vitro inhibition by SFO of bone formation and 1,25-dihydroxy-vitamin D production in renal tubules.

A 60-year-old man with portal hypertensive gastropathy due to type C liver cirrhosis developed severe bone pains, marked hypophosphatemia with inappropriately increased urinary excretion of phosphate (%TRP; 9.6%), and hyperalkaline phosphatasia, after intravenous administration of saccharated ferric oxide (SFO) at a dose of 80-240 mg/week over a period of more than 5 years. The total iron infused was estimated to be more than 25 g. On a diagnosis of SFO-induced osteomalacia, the infusion of iron was immediately discontinued, and phosphate and vitamin D2 (1000 IU/day) were administered. Serum levels of 25-OHD2 increased after 1 week, whereas levels of 1,25-(OH)2D2 did not increase until 3 months later, accompanied by improvement of renal tubular reabsorption of phosphate and gradual improvement of the bone pains. The patient has been doing well for the last 2 years, with normal serum levels of phosphate, calcium, and alkaline phosphatase, without any supplementation of phosphate, vitamin D, or iron-containing agents. In primary culture of neonatal mouse renal tubules, in which 1,25-(OH)2D3 was produced from 25-OHD3 in response to PTH, SFO significantly inhibited PTH-induced production of 1,25-(OH)2D3 at 30 mumol/L, which is attainable in the urine of patients receiving a therapeutic intravenous dose of SFO. Furthermore, SFO decreased the calcium content and inhibited 45Ca incorporation in cultured fetal mouse parietal bones at 3 mumol/L. Such SFO concentration may be transiently observed in the plasma of patients receiving excessive intravenous doses of SFO for a prolonged period. These in vitro findings together with the clinical observations suggest that SFO, after filtration through the glomerulus and reabsorption in the proximal renal tubules, impaired proximal renal tubular function, such as tubular reabsorption of phosphate and 1 alpha-hydroxylase activity, leading to hypophosphatemic osteomalacia. Furthermore, it is highly likely that SFO in the peripheral blood, when transferrin is saturated with iron, may impair bone formation and aggravate osteomalacia. Although SFO-induced osteomalacia is reversible simply by discontinuation of the agent, excessive and prolonged administration of SFO should be avoided.

Alkaline Phosphatase↗

PubMed1997

Experimental acute glomerulonephritis induced in the rabbit with a specific streptococcal antigen.

FITC-labelled IgG obtained from patients convalescing from acute poststreptococcal glomerulonephritis (APSGN) stains glomeruli of patients with early APSGN. We previously reported a streptococcal antigen (preabsorbing antigen (PA-Ag)) that preabsorbed the stain out of sera from the convalescent patients and thus prevented glomerular staining. To confirm the nephritogenicity of PA-Ag, we administered up to 40 mg of this antigen to rabbits for 8 days and observed them for up to 9 weeks. Immunohistological analysis showed diffuse and global glomerular staining for C3 without notable staining for gamma-globulin. Light microscopic examinations revealed slight to moderate proliferative glomerulonephritis with exudative change. Control rabbits, which received similar doses of bovine serum albumin, did not show significant staining for C3. A transient and significant decrease in CH50 was observed from weeks 3 to 7 (9.7 +/- 0.3 U/ml at week 3; normal range 12.9 +/- 0.6 U/ml). This experimental model showed a resemblance to immunological and immunohistological features of APSGN in humans. Although the precise mechanisms are yet to be determined, complement activation by PA-Ag seems to hold a key position in this model and in the human disease.

Acute Disease↗

PubMed1997

Differential display analysis of murine collagen-induced arthritis: cloning of the cDNA-encoding murine ATPase inhibitor.

We used the differential display technique in order to detect a new gene involved in murine type II collagen-induced arthritis (CIA). In this study, we have identified a novel gene, IF1, whose expression level is increased during the natural course of CIA. Northern blot analyses suggest that IF1 is involved in the natural course of CIA but is not involved as a trigger of CIA. IF1 is considered to be the murine ATPase inhibitor gene for several reasons. First, IF1 shows an extremely high homology to the rat ATPase inhibitor; the highly conserved region between rat and bovine amino acid residues 22-45, which is the minimum sequence showing ATPase inhibitory activities, is also highly conserved in IF1. Second, IF1 possesses a histidine-rich region in the same area, which is thought to be important for regulation of mammalian inhibitors. Third, the tissue distribution of IF1 is very suggestive. The expression of IF1 was very strong in energetic organs such as the heart, brain and kidney, and the development of arthritis requires great amounts of ATP. As arthritis develops rapidly, the cellular ATP pool may be decreased. Before the ATP pool is exhausted, the ATPase inhibitor may serve as a brake for ATP hydrolysis. If the supply of free energy can be reduced, the inflammation of arthritis may in turn be restored. Our hypothesis is that the ATPase inhibitor is involved in regulating the inflammatory responses.

Amino Acid Sequence↗

PubMed1997

Mechanisms of central motor reorganization in pediatric hemiplegic patients.

Twenty hemiplegic patients were studied with transcranial magnetic stimulation (TMS). Motor evoked potentials (MEPs) of the biceps brachii (BB) and the abductor pollicis brevis muscles (APB) were recorded on both sides simultaneously. TMS was carried out with an 8-shaped coil over different scalp positions in the intact hemisphere. Bilateral MEPs of BB were elicited in patients with later childhood lesions as well as early lesion, but those of APB were only elicited in the latter (up to 2 years). In patients with prenatal or birth lesion on BB and in all patients on APB, cortical maps of MEP amplitude of paretic and non-paretic sides showed similar distributions. There were no remarkable differences in mean latency between both sides, and correlation coefficients of MEP amplitude between both sides were high in these patients. In patients with postnatal lesion on BB, MEP maps of both sides showed different distributions, ipsilateral MEP latencies were delayed and correlation coefficients were low. We suspect that ipsilateral MEPs after early lesion derive from axonal sprouting both in the proximal and the distal muscles. After postnatal lesion, other mechanisms of ipsilateral motor projection take place in the proximal muscles, but not in the distal ones.

Adolescent↗

PubMed1997

KRN4884, a novel K channel opener: antihypertensive effects in conscious renal hypertensive dogs.

We examined the antihypertensive effects of KRN4884, 5-amino-N-[2-(2-chlorophenyl)ethyl]-N'-cyano-3-pyridinecarbocamidine+ ++, in normotensive dogs, a high-renin model acute renal hypertensive dog (RHD), and a low-renin model chronic RHD in the conscious state, compared with levcromakalim and nilvadipine. KRN4884 decreased mean blood pressure (MBP) at a dose of 0.1 mg/kg p.o. in normotensive dogs and both RHDs. The decrease in MBP was greater in both RHDs than in normotensive dogs, and there were no significant differences between the two RHDs. A transient increase in heart rate (HR) accompanied the increase in MBP in all three types of dogs. In the chronic RHD, KRN4884 at doses of 0.05, 0.1, and 0.2 mg/kg produced a dose-dependent decrease in MBP. The antihypertensive effect of KRN4884 (0.1 mg/kg) was similar to those of levcromakalim (0.05 mg/kg) and nilvadipine (1.0 mg/kg) in magnitude and more prolonged than those of the compounds. The tachycardia induced by KRN4884 was similar to that induced by levcromakalim and was stronger than that induced by nilvadipine. In the 15-day repeated oral-administration study, KRN4884 (0.1 mg/kg) induced sustained hypotensive effects and transient increases in HR and plasma renin activity. No tolerance to the antihypertensive effect of KRN4884 was observed during a 15-day repeated dosing period. After withdrawal of KRN4884, no rebound phenomena in MBP and HR were observed. Neither the maximal concentration nor area under the curve (AUC) of KRN4884 in plasma were changed at days 1, 8, and 15. These data indicate that KRN4884 produces a strong and persistent antihypertensive response in both low-renin and high-renin models of RHD in a conscious state, which suggests that KRN4884 may be useful as an antihypertensive agent.

Animals↗

PubMed1997

Identification of T-cell epitope sequences on an important mite antigen.

BACKGROUND: T-cell epitopes on Der 1 and Der 2 groups, the major mite allergens, have been intensively analysed, while those on the other important allergens remain to be elucidated. We have cloned four cDNAs coding for important mite allergens on the basis of frequency and capacity of IgE binding. Stimulatory action of glutathione S-transferase-fused Mag1 on lymphocytes from mite-allergic patients was relatively high among them. OBJECTIVE: To identify T-cell epitopes on Mag1, we studied the stimulating activity of truncated Mag1 proteins and synthetic peptides on proliferative response of lymphocytes from mite antigen-immunized mice and mite-sensitive patients. METHODS: Truncated Mag1 proteins were expressed as a fusion protein with beta-galactosidase in Escherichia coli pop2136 carrying a variety of deleted Mag1 inserts. Murine T-cell epitope regions were estimated by the truncated antigen-induced lymphocyte proliferation assay. Overlapping peptides covering the whole sequence of the presumed T-cell epitope regions were synthesized to identify the epitope core sequences using murine and human Mag1-specific T-cell lines. RESULTS: Amino acid range 56-70 on Mag1 molecule showed remarkable stimulatory action on murine T cells, while amino acid ranges 51-65 and 86-100 had potent stimulatory activity on human T cells. CONCLUSIONS: These results suggest that Mag1 is a valuable antigen suitable for studies on T-cell responses and T-cell epitopes in mice and humans.

Animals↗

PubMed1997

In vitro and in vivo vasodilating effects of KRN4884, Ki1769 and Ki3005, pyridinecarboxamidine derivatives.

The vasodilating potencies and mechanism of action of a novel pyridinecarboxamidine derivative, KRN4884 [5-amino-N-[2-(2-chlorophenyl)ethyl]-N'-cyano-3-pyridinecarboxamidine ] were compared with those of Ki1769 [N-cyano-N'-(2-phenylethyl)-3-pyridinecarboxamidine] and Ki3005 [N-[2-(2-chlorophenyl)ethyl]-N'-cyano-3-pyridinecarboxamidine] in rat isolated aortas and in anesthetized normotensive rats. In vitro. KRN4884 (10(-10)-10(-6) M). Ki1769 (10(-8)-10(-5) M) and Ki3005 (10(-10)-10(-6) M) produced concentration-dependent relaxations. KRN4884 was about 100- and 10-fold more potent than Ki1769 and Ki3005, respectively. The relaxant effects of these compounds were antagonized by glibenclamide. In vivo, KRN4884 (1-10 micrograms/kg, intravenously [i.v.]), Ki1769 (10-100 micrograms/kg, i.v.) and Ki3005 (3-30 micrograms/kg, i.v.) produced dose-dependent decreases in mean blood pressure with slight increases in heart rate. At 10 micrograms/kg, i.v., the hypotensive effect of KRN4884 was about the same as that of Ki3005 and about 5-fold more pronounced than that of Ki1769. The hypotensive action remained for a longer period after KRN4884 administration. In rats pre-treated with glibenclamide (20 mg/kg, i.v.), the hypotensive effect of KRN4884 was abolished. These results suggest that the effect of KRN4884 in vitro and in vivo is based on its K channel opening action and that the in vitro vasorelaxant effect of these compounds in aortic rings does not predict their relative hypotensive effect in vivo.

Animals↗

PubMed1997

Nitric oxide as an inflammatory mediator of radiation pneumonitis in rats.

Radiation pneumonitis is a major complication of radiation therapy. To elucidate the mechanisms of radiation-induced pneumonitis, we studied nitric oxide (NO) produced from lung tissues using a model of unilaterally irradiated rats. Our results demonstrated that alveolar macrophages (AM) produced NO after irradiation, and the expression of inducible NO synthase (NOS) in both AM and alveolar epithelial cells was increased. Furthermore, the progression of radiation pneumonitis was reduced with the in vivo treatment of the NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). The effect of L-NAME was further confirmed by the inhibition of mRNA expression for procollagen-alpha1 type III of the lung. With these results, NO produced from AM and alveolar epithelial cells after irradiation may be an important mediator in the progression of radiation pneumonitis.

Animals↗

PubMed1997

Construction of Escherichia coli-Bifidobacterium longum shuttle vector transforming B. longum 105-A and 108-A.

A shuttle vector, pBLES100, was constructed by cloning a Bifidobacterium longum plasmid and a gene encoding spectinomycin adenyltransferase AAD(9) from Enterococcus faecalis into the Escherichia coli vector pBR322. Stable transformants with this plasmid were obtained with an efficiency of 2.2 x 10(4) transformants/microgram DNA or 6.9 x 10(-5) transformants/cell/microgram DNA under the optimal conditions of 10.0 kV/cm, 200 omega, and 25 microF, using B. longum 105-A harvested at late log phase of growth.

Bifidobacterium↗

PubMed1997

Morphological change in tumor endothelial cells induced by natural-type human tumor necrosis factor.

The effects of natural-type human tumor necrosis factor (nh-TNF) on tumor endothelial cells of experimental brain tumors were investigated electron microscopically. Tumor vessels with hypertrophic endothelial cells were observed 12 and 24 hr after an intralesional administration of 5,000 U of nh-TNF. Increased biosynthetic organelles such as the Golgi complex and rough endoplasmic reticulum were evident in the plump cytoplasms. These endothelial cells resembled those in high endothelial venules (HEV) functionally characterized by the high permeability of leukocytes. In addition, close interactions between these endothelial cells and leukocytes were observed. Our findings indicated that nh-TNF could promote the morphological change in tumor endothelial cells into HEV-like cells.

Animals↗

PubMed1997

A new method of bone tissue measurement based upon light scattering.

In recent years, time-resolved spectroscopy systems using near infrared pulsed laser have been applied to develop optical computed tomography. We applied this technique to measure the optical properties of osseous tissues. First, we gradually demineralized 10 mm blocks of bovine trabecular bone with EDTA, maintaining the absorption characteristics and structure but varying the hydroxyapatite content, thus creating specimens differing only in light scattering properties. We used computer densitograms to assess light penetration, and analyzed the correlation with bone mineral density (BMD) as with dual-energy X-ray absorptiometry scans. The light penetration increased with decreasing BMD. Second, using the above-mentioned pulsed laser time-resolved spectroscopy system, we investigated the correlation between the BMD and the time response waveforms of 10-mm blocks of bovine cortical bone, trabecular bone, and surrounding tissue as well as human trabecular bone. The human lumbar vertebral bone also displayed an inverse correlation between BMD and maximum light penetration and a positive correlation between BMD and peak time delay. This is the first demonstration of a correlation between BMD and light scattering properties showing that BMD can indeed be measured with light. Our results show the possibility of obtaining information on internal bone structure and composition in vivo through assessment of the waveforms obtained by a time-resolution system in the near infrared region.

Animals↗

PubMed1997

Arrhythmia curve interpretation using a dynamic system model of the myocardial pacemaker.

A problem of identifying the phase response curve of the myocardial pacemaker was investigated using a simple dynamic system model of cardiac arrhythmia. A hybrid optimization method of a genetic algorithm and a local optimization technique was employed to obtain a solution of the model fitting. The method was applied to two categories of arrhythmias, ventricular parasystole and high-degree AV block. The present study offered a new insight into the mechanism of cardiac arrhythmias.

Animals↗