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M Ichimura

Publications and source records attributed to M Ichimura.

At least 37 records · Page 2Linked to original sources
PubMed1998

Unique binding pocket for KW-4679 in the histamine H1 receptor.

The histamine H1 receptor has an aspartate (Asp) residue in transmembrane helix 3 (TM3), which is well-conserved among biogenic amine receptors. The Asp residue is one of the most crucial amino acids for ligand binding. The tested histamine H1 receptor antagonists with tri- and tetracyclic structures were not selective for histamine H1 receptors and showed affinity for several other biogenic amine receptors. In contrast, KW-4679 ((Z)-11-[3-(dimethylamino)propylidene]-6,11-dihydrodibenz[b, e]oxepin-2-acetic acid hydrochloride), a tricyclic compound, was a selective histamine H1 receptor antagonist. [3H]KW-4679 had high affinity (Kd value of 2.5 +/- 0.12 nM) for wild-type human histamine H1 receptors. In the [3H]KW-4679 binding assay, replacement of Asp107 by alanine by site-directed mutagenesis greatly reduced the affinities (280-2100-fold) of tri- and tetracyclic compounds, whereas this mutation led to a comparatively small reduction (14-fold) in KW-4679 affinity. These results demonstrate that the tested tri- and tetracyclic histamine H1 receptor antagonists which have a tight interaction with the Asp residue are not selective for the histamine H1 receptor. Furthermore, the high selectivity of KW-4679 might be explained by a unique binding pocket, which consists of the Asp residue and other acceptor sites, in the histamine H1 receptor.

Animals↗
PubMed1998

Clinicopathological features of chronic inflammatory demyelinating polyradiculoneuropathy in childhood.

The clinical, electrophysiological, and pathological findings, and the therapeutic characteristics in ten children with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), whose onset age was less than 16 years, were evaluated. The clinical progression pattern of the initial phase divided the patients into two groups. One group (six patients) showed a subacute progression for up to 2 months after onset and a subsided progression over 3 months. Three patients in this group had a preceding febrile episode. The other group (four patients) showed a chronic insidious progression for more than 3 months. The former group of patients revealed a favourable response to corticosteroid therapy as compared with the latter group. However, other clinical and laboratory features at the peak impairment were not distinguishable between these two groups. Motor dominant neuropathy was common to all patients, and only three cases showed sensory disturbance on the distal limbs. No cases revealed cranial nerve involvement. Motor and sensory nerve conduction and sural nerve biopsy studies revealed the demyelinating nature of the neuropathy. These clinicopathological features suggest that the subacute progression form frequently associated with prodromal episode and rather favourable corticosteroid response is characteristic in childhood CIDP, while the chronic insidious progression form is indistinguishable from the common adult CIDP.

Adolescent↗
PubMed1998

Affinity isoelectric focusing of human serum apolipoprotein B-containing lipoproteins on agarose gels with cyclodextrins.

In an attempt to subfractionate apolipoprotein B-containing lipoproteins (apoB-Lp), agarose isoelectric focusing (IEF) of apoB-Lp in human sera was carried out in the presence of two kinds of cyclodextrins (CDs), which have different affinities for cholesterol. ApoB-Lp in the agarose gels was detected by immunofixation, followed by protein staining. In the presence of both 11.4 mg/mL alpha-CD and 3.51 mg/mL beta-CD, but not either one alone, IEF separated a maximum of six apoB-Lp bands. Electrophoresis failed to separate the apoB-Lp subfractions under similar conditions with CDs. The patterns of apoB-Lp in IEF with the CDs appeared to differ in some sera. Since the subfractions of apoB-Lp can be separated without ultracentrifugation of serum, the present method serves for the screening of apoB-Lp heterogeneity on native serum lipoproteins.

Apolipoproteins B↗
PubMed1998

Prevention of hyperlipidemic acute pancreatitis during pregnancy with medium-chain triglyceride nutritional support.

CONCLUSION: A combination of diet therapy, nutritional support with medium-chain triglycerides (MCT), and well-planned preterm Cesarean delivery on demand is an effective measure to prevent gestational hyperlipidemic pancreatitis and leads to successful childbirth. BACKGROUND: Prevention and therapy of gestational hyperlipidemic pancreatitis are important, although difficult, because the condition carries a high maternal and fetal morbidity and mortality. RESULTS: We describe a 32-yr-old female with lipoprotein lipase-deficient familial hypertriglyceridemia who had recurrent episodes of acute pancreatitis. The third episode occurred with worsened hyperlipidemia 7 yr earlier at 32 wk of her first pregnancy and resulted in fetal death. The fourth and fifth episodes were also accompanied by marked hyperlipidemia probably caused by drug discontinuance and dietary noncompliance. She became pregnant. Serum triglyceride levels were controlled below 2000 mg/dL by strict monitoring with low-fat, low-calorie diet and MCT nutritional support. A premature but healthy infant was born by Cesarean delivery at 36 wk of gestation when the mother presented with mild abdominal pain and was found to have uterine contractions. The ensuing clinical course has been uneventful.

Acute Disease↗
PubMed1998

Tissue distribution of pathological lesions and Hu antigen expression in paraneoplastic sensory neuronopathy.

We investigated the distribution of lesions and Hu antigen expression in two autopsied cases of anti-Hu antibody-positive paraneoplastic sensory neuronopathy (carcinomatous subacute sensory neuropathy). Pathological changes in both patients were limited to the primary sensory neurons, some of the sympathetic ganglia and hippocampal regions. The lesions showed a multifocal distribution that differed among the spinal segmental levels and in the individual dorsal root ganglia as well as in the nerve fascicles. Western blot analysis of the patients' serum revealed that Hu antigens were extensively and widely expressed throughout the central nervous system, sensory and sympathetic ganglia and cancer cells, but not in the non-neural visceral tissues. Reverse transcriptase-polymerase chain reaction also showed that the Hu D, Hu C, Hel-N1 and Hel-N2 mRNAs were extensively and widely expressed through the neural tissues and cancer cells, but not in the visceral tissues. Thus, the distribution of antigen expression was very different from that of the lesions. Taken together with the distribution of lesions and Hu antigen expression, it is suggested that factors other than anti-Hu antibodies are also involved in the pathogenesis of this neuronopathy.

Adenocarcinoma↗
PubMed1997

Anti-inflammatory and bronchodilator properties of KF19514, a phosphodiesterase 4 and 1 inhibitor.

We investigated the effects of KF19514 (5-phenyl-3-(3-pyridyl)methyl-3H-imidazo[4,5-c][1,8]naphthyridin-4 (5H)-one) on bronchoconstriction and allergic inflammation in guinea pigs and on tumor necrosis factor-alpha production in mice. KF19514 inhibited phosphodiesterase 4 (IC50 = 0.40 microM) and phosphodiesterase 1 (IC50 = 0.27 microM) derived from canine tracheal smooth muscles. KF19514 relaxed contracted tracheal smooth muscle and had a potent inhibitory effect on antigen-induced bronchoconstriction (EC50 = 0.058 microM) in vitro. Intravenous administration of KF19514 inhibited histamine-induced bronchoconstriction (ID50 = 2.8 microg/kg i.v.). Moreover, oral administration of KF19514 inhibited anaphylactic bronchoconstriction (ID50 = 0.2 mg/kg p.o.), and eosinophil infiltration in airway stimulated with platelet-activating factor (PAF) or antigen. KF19514 also produced a significant inhibition of tumor necrosis factor-alpha production in mice (ID50 = 0.023 mg/kg p.o.). Finally, KF19514 completely inhibited antigen-induced hyperreactivity at 0.1 mg/kg p.o. These results demonstrate that KF19514 may have efficacy in the treatment of asthma.

Anaphylaxis↗
PubMed1997

Enzymic O-methylation of isoliquiritigenin and licodione in alfalfa and licorice cultures.

S-Adenosyl-L-methionine (SAM): isoliquiritigenin (2',4,4'-trihydroxychalcone) 2'-O-methyltransferase (CHMT) of alfalfa (Medicago sativa) catalyses the formation of 4,4'-dihydroxy-2'-methoxychalcone, which is the most potent inducer of nodulation-genes of Rhizobium meliloti, the symbiont of alfalfa which forms nitrogen-fixing nodules. SAM: licodione 2'-O-methyltransferase (LMT) is involved in the biosynthesis of a retrochalcone in cultured licorice (Glycyrrhiza echinata) cells and has been shown to be induced as a defence response of the cells. Because licodione exists in an equilibrium mixture of tautomeric 2',4,4',beta-tetrahydroxychalcone (major) and 1-(2,4-dihydroxyphenyl)-3-(4-hydroxyphenyl)-1,3-propanedione (minor), the apparent mode of action of both enzymes is very similar. In this study, cultured alfalfa cells were shown to exhibit rapid and transient increases in the extractable activities of both CHMT and LMT after treatment with yeast extract (YE). Treatment of solution-cultured alfalfa seedlings with YE also resulted in a similar induction of both CHMT and LMT activities in the roots, but no activity was detected in the shoots. These activities were attributed to a single gene product, the CHMT protein, as extracts of Escherichia coli transformed with the CHMT cDNA exhibited both CHMT and LMT activities. In contrast, in G. echinata cells, LMT was induced after YE treatment, but no CHMT activity was observed. It is concluded that alfalfa CHMT and licorice LMT are distinct enzymes, the former displaying the wider substrate specificity.

Chalcone↗
PubMed1997

Does recurrent acute pancreatitis lead to chronic pancreatitis? Sequential morphological and biochemical studies.

The pathogenesis of chronic pancreatitis (CP) has been debated as to whether it is a de novo process or the consequence of acute pancreatitis (AP). We investigated whether recurrent AP in rats leads to CP, by sequential morphological and biochemical studies. Thirty male Wistar rats were fed a choline-deficient diet with intraperitoneal ethionine injections twice daily at a dose of 60 mg/100 g body weight twice weekly, and six rats were killed at 4, 6, and 8 weeks; the remaining 12 rats, followed without further treatment, were killed at 12 and 16 weeks. The pancreata from study and control groups were examined by histology, immunohistochemistry, and bio- and immunoassays. Histologically, moderate to severe intra- and perilobular fibrosis and other CP-like lesions appeared maximally at 8 weeks. Immunohistochemically, the earliest extracellular matrix change was strong fibronectin staining at 4 weeks, with a progressive increase to 8 weeks. Collagens I and III came to show strong, and collagen IV moderate, interstitial staining at 6-8 weeks. These morphological changes, however, returned to nearly normal at 16 weeks. Prolyl hydroxylase was significantly elevated at 4 and 6 weeks and normalized after 8 weeks, with no significant change in collagenase. In conclusion, our results suggest that even severe CP-like lesions induced by recurrent AP are reversible in the absence of persistently elevated prolyl hydroxylase and/or suppressed collagenase. The mechanism regulating these changes remains to be studied further.

Acute Disease↗
PubMed1997

Axonal pathology in Japanese Guillain-Barré syndrome: a study of 15 autopsied cases.

We assessed the frequency and extent of axonal involvement in the ventral spinal roots in 15 Japanese autopsied patients with Guillain-Barré syndrome (GBS). Teased-fiber preparation revealed that five had predominantly axonal pathology with minimal segmental demyelination, seven had predominantly segmental demyelination with minimal axonal changes, two patients showed a mixture of both conditions, and one patient did not show any particular pathologic changes. We confirmed axon loss by immunohistochemical analysis of high-molecular-weight neurofilament protein. Macrophage invasion was a prominent feature in nerves with predominantly axonal changes. Two patients with severe axonal involvement and prolonged clinical courses exhibited motor neuron loss with astrogliosis in the ventral horns. These results suggest that autopsy-verified axonal involvement is more frequent among Japanese GBS patients than in Caucasian populations but less frequent than that reported from northern China.

Adult↗
PubMed1997

[Our HPN guidance].

As many medical services, medicines and instruments are provided for home treatment, the needs of home care are on the increase. The support of the patient's family is required to perform HPN and provide care. There are many problems and fears of self-care and one's own performance HPN. We attempt to make HPN guidance. The selected key person in patient's family is directed by the same nurse using schema and illustrations on HPN. The items to be acquired the theory and practice are assessed together. HPN timetable is done according to the key person's schedule. Before discharge, the patient and family contact with the visiting care nurse team (visiting nurse, doctor, outpatient clinic). The guidance and practice of HPN according to the schedule or offering it to the patient and family are readily accepted. It is important to remove the problems and fears associated with establishing a medical support system.

Aged↗
PubMed1996

KS-505a, an isoform-selective inhibitor of calmodulin-dependent cyclic nucleotide phosphodiesterase.

The effects of KS-505a, a novel microbial metabolite, on the activity of calmodulin-dependent cyclic nucleotide phosphodiesterase (CaM-PDE) were investigated. (1) KS-505a potently inhibited the purified 61 kDa isoenzyme of CaM-PDE from bovine brain and required much higher doses to inhibit the purified 59 kDa isoenzyme of CaM-PDE from bovine heart. The inhibition of both isoenzymes was observed only in the presence of calcium-activated calmodulin (Ca2+/CaM). The IC50 values for the 61 and 59 kDa isoenzymes were 0.17 and 13 microM respectively with 20 microM cAMP as a substrate. (2) Kinetic analysis indicated that the inhibitory mode of KS-505a for the 61 kDa isoenzyme was competitive with respect to Ca2+/CaM; the K1 for KS-505a was 0.089 microM. The inhibition was not competitive with respect to the substrates cAMP or cGMP. (3) KS-505a did not interfere with the interaction between Ca2+/CaM and n-phenyll-naphthylamine, a hydrophobic fluorescent probe, nor was it adsorbed to CaM-conjugated gels in the presence of Ca2+, thereby indicating that KS-505a does not bind to Ca2+/CaM. (4) Trypsin-activated 61 kDa isoenzyme, which lacked the Ca2+/CaM-binding domain, was not inhibited by KS-505a at less than micromolar concentrations. Taken together, these results suggest that KS-505a apparently bound to a site in the Ca2+/CaM-binding domain of the 61 kDa isoenzyme and selectively inhibited Ca2+/CaM-activated 61 kDa isoenzyme activity. (5) In rat hippocampal slices, KS-505a at 10 micronM increased the intracellular cAMP concentration to approximately three times the basal level, whereas in rat striatal slices it had no effect on the cAMP concentration at concentrations of 1.0-10 microM, suggesting that each CaM-PDE isoenzyme functions differentially in these regions. These results demonstrate that KS-505a is a highly potent selective inhibitor both in vitro and in vivo and distinguishes between subfamily members within the CaM-PDE family.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1996

The role of adenosine A2a receptors in regulating GABAergic synaptic transmission in striatal medium spiny neurons.

We demonstrated an adenosine A2a receptor-mediated disinhibition of medium spiny projection neurons using intracellular recording and the whole-cell patch-clamp recording applied to these cells, visually identified in thin rat striatal slices. The A2a receptor agonist 2-[p-(2-carboxyethyl) phenylethylamino]-5'-N- ethylcarboxamido adenosine (CGS-21680; 0.3-10 microM) suppressed GABAergic synaptic transmission onto these cells in a manner inhibited by the A2a receptor-selective antagonist (E)-8-(3,4-dimethoxystyryl)-1,3-dipropyl-7-methylxanthine (0.1-1.0 microM). The A1 receptor antagonists had no effect on the CGS-21680-induced suppression. Analysis of spontaneous miniature inhibitory synaptic currents indicated that suppression of intrastriatal GABAergic synaptic transmission was attributable to presynaptic, but not postsynaptic, A2a receptors. Therefore, the A2a receptor may regulate striatal output activity by relieving GABA-mediated inhibition of the medium spiny projection neurons, which explains the ability of purinergic agents to affect motor control.

Adenosine↗
PubMed1996

Studies of cardiotonic agents. 8. Synthesis and biological activities of optically active 6-(4-(benzylamino)-7-quinazolinyl)-4,5-dihydro-5-methyl-3(2H)- pyridazinone (KF15232).

We previously reported that (+/-)-6-(4-(benzylamino)-7-quinazolinyl)-4,5- dihydro-5-methyl-3(2H)-pyridazinone (+/-)-1, KF15232) showed potent cardiotonic activity with a strong myofibrillar Ca(2+)-sensitizing effect. As an extension of our work, we attempted to synthesize optically active 1. (+/-)-4-(4-(Benzylamino)-7-quinazolinyl)-3-methyl-4-oxobutyric acid (-)-menthyl ester (6) was separated into both diastereoisomers, and each was converted to optically pure 1 (> 99% ee) in an enantioselective manner. In order to determine the absolute configuration of the isomers, an alternative synthesis of optically active 1 was employed. The precursor of (-)-1 ((+)-9) was obtained by enantioselective synthesis from (R)-D-alanine. Consequently, we concluded that the absolute configuration of (-)-1 at the 5-position of the pyridazinone ring was R. The cardiotonic effects and inhibitory activities to PDE III and V of racemic 1 and (-)-1 were more potent than those of (+)-1. These compounds also demonstrated greater vasorelaxant effects in guinea pig aorta. In contrast, (+)-1 showed only weak cardiotonic and vasodilating effects, although the compound displayed potent Ca(2+)-sensitizing activity. Racemic and (-)-1 attracted our interest for the treatment of congestive heart failure.

Animals↗
PubMed1996

KW-3902, a selective high affinity antagonist for adenosine A1 receptors.

1. We demonstrate that 8-(noradamantan-3-yl)-1,3-dipropylxanthine (KW-3902) is a very potent and selective adenosine A1 receptor antagonist, assessed by radioligand binding and cyclic AMP response in cells. 2. In rat forebrain adenosine A1 receptors labelled with [3H]-cyclohexyladenosine (CHA), KW-3902 had a Ki value of 0.19 nM, whereas it showed a Ki value of 170 nM in rat striatal A2A receptors labelled with [3H]-2-[p-(2-carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamidoad enosine (CGS21680), indicating 890 fold A1 receptor selectivity versus the A2A receptor. KW-3902 at 10 microM showed no effect on recombinant rat A3 receptors expressed on CHO cells. 3. Saturation studies with [3H]-KW-3902 revealed that it bound with high affinity (Kd = 77 pM) and limited capacity (Bmax = 470 fmol mg-1 of protein) to a single class of recognition sites. A high positive correlation was observed between the pharmacological profile of adenosine ligands inhibiting the binding of [3H]-KW-3902 and that of [3H]-CHA. 4. KW-3902 showed potent A1 antagonism against the inhibition of forskolin-induced cyclic AMP accumulation in DDT1 MF-2 cells by the A1-selective agonist, cyclopentyladenosine with a dissociation constant (KB value) of 0.34 nM. KW-3902 antagonized 5'-N-ethylcarboxamidoadenosine-elicited cyclic AMP accumulation via A2B receptors with a KB value of 52 nM. 5. KW-3902 exhibited marked species-dependent differences in the binding affinities. The highest affinity was for the rat A1 receptor (ki = 0.19 nM) and these values for guinea-pig and dog A1 receptors were 1.3 and 10 nM, respectively.

Adenosine↗
PubMed1996

Effect of terfenadine and KW-4679, a novel antiallergic compound, on action potential of guinea pig ventricular myocytes.

It has been reported that terfenadine caused torsade de pointes ventricular arrhythmias. The prolongation of action potential duration (APD) in ventricles is considered to be one of the mechanisms of this adverse effect. We examined the effect of antiallergic drugs, terfenadine and KW-4679 ((Z)-11-[3-(dimethylamino)propylidene]-6,11-dihydrodibenz[b, e]oxepin- 2-acetic acid hydrochloride), on action potentials in isolated guinea pig ventricular myocytes. Terfenadine (30 nM-1 microM) increased APD in a concentration-dependent manner. On the other hand, KW-4679 (0.1 microM-100 microM) exerted no significant effects on action potential parameters. These results present no evidence that KW-4679 has the possibility to cause ventricular arrhythmias.

Action Potentials↗
PubMed1996

[Comparative studies on the time course of proliferating cell nuclear antigen and bromodeoxyuridine staining pattern in regenerating rat liver cells].

Immunohistochemical staining pattern of proliferating cell nuclear antigen (PCNA) was examined in regenerating rat liver specimens fixed under the various conditions (10% buffered formalin for 6hr, 1% paraformaldehyde for 6hr, 100% methanol for 4hr, 70% ethanol for 6hr). Time course of PCNA staining pattern after hepatectomy in the specimens fixed with 100% methanol or 70% ethanol coincided closely with that of bromodeoxyuridine (BrdU) staining pattern, which is known to be standard marker of cell proliferation. Similar result was obtained in fixation with 10% buffered formalin (10% BF) or 1% paraformaldehyde (1% PFA) when only granular staining pattern of PCNA was evaluated. These findings suggest that granular immunostaining of PCNA in tissue specimens fixed with 100% methanol, 70% ethanol, 10% BF or 1% PFA is useful for evaluating the extent of cell proliferation.

Animals↗
PubMed1995

Quasifree (d

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Journal Article↗