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Biomedical subjects

M Maeno

Publications and source records attributed to M Maeno.

At least 37 records · Page 2Linked to original sources
PubMed1996

Involvement of Ras/Raf/AP-1 in BMP-4 signaling during Xenopus embryonic development.

Previously, we elucidated the role of bone morphogenetic protein 4 (BMP-4) in the dorsal-ventral patterning of the Xenopus embryo by using a dominant negative mutant of the BMP-4 receptor (DN-BR). The present paper describes the involvement of Ras, Raf, and activator protein 1 (AP-1) in BMP-4 signaling during Xenopus embryonic development. The AP-1 activity was determined by injecting an AP-1-dependent luciferase reporter gene into two-cell-stage Xenopus embryos and measuring the luciferase activity at various developmental stages. We found that injection of BMP-4 mRNA increased AP-1 activity, whereas injection of DN-BR mRNA inhibited AP-1 activity. Similar inhibitory effects were seen with injection of mRNAs encoding dominant negative mutants of c-Ha-Ras, c-Raf, or c-Jun. These results suggest that the endogenous AP-1 activity is regulated by BMP-4/Ras/Raf/Jun signals. We next investigated the effects of Ras/Raf/AP-1 signals on the biological functions of BMP-4. DN-BR-induced dorsalization of the embryo, revealed by the formation of a secondary body axis or dorsalization of the ventral mesoderm explant analyzed by histological and molecular criteria, was significantly reversed by coinjection of [Val12]Ha-Ras, c-Raf, or c-Jun mRNA. Furthermore, the BMP-4-stimulated erythroid differentiation in the ventral mesoderm was substantially inhibited by coinjection with the dominant negative c-Ha-Ras, c-Raf, or c-Jun mutant. Our results suggest the involvement of Ras/Raf/AP-1 in the BMP-4 signaling pathway.

Animals↗
PubMed1996

Nature and distribution of chondroitin sulphate and dermatan sulphate proteoglycans in rabbit alveolar bone.

The type and distribution of mineral binding and collagenous matrix-associated chondroitin sulphate and dermatan sulphate proteoglycans in rabbit alveolar bone were studied biochemically and immunocytochemically, using three monoclonal antibodies (mAb 2B6, 3B3, and 1B5). The antibodies specifically recognize oligosaccharide stubs that remain attached to the core protein after enzymatic digestion of proteoglycans and identify epitopes in chondroitin 4-sulphate and dermatan sulphate; chondroitin 6-sulphate and unsulphated chondroitin; and unsulphated chondroitin, respectively. In addition, mAb 2B6 detects chondroitin 4-sulphate with chondroitinase ACII pre-treatment, and dermatan sulphate with chondroitinase B pre-treatment. Bone proteins were extracted from fresh specimens with a three-step extraction procedure: 4 M guanidine HCl (G-1 extract), 0.4 M EDTA (E-extract), followed by guanidine HCl (G-2 extract), to characterize mineral binding and collagenous matrix associated proteoglycans in E- and G2-extracts, respectively. Biochemical results using Western blot analysis of SDS-polyacrylamide gel electrophoresis of E- and G2-extracts demonstrated that mineral binding proteoglycans contain chondroitin 4-sulphate, chondroitin 6-sulphate, and dermatan sulphate, whereas collagenous matrix associated proteoglycans showed a predominance of dermatan sulphate with a trace of chondroitin 4-sulphate and no detectable chondroitin 6-sulphate or unsulphated chondroitin. Immunocytochemistry showed that staining associated with the mineral phase was limited to the walls of osteocytic lacunae and bone canaliculi, whereas staining associated with the matrix phase was seen on and between collagen fibrils in the remainder of the bone matrix. These results indicate that mineral binding proteoglycans having chondroitin 4-sulphate, dermatan sulphate, and chondroitin 6-sulphate were localized preferentially in the walls of the lacunocanalicular system, whereas collagenous associated dermatan sulphate proteoglycans were distributed over the remainder of the bone matrix.

Animals↗
PubMed1996

Identification of an antihypertensive peptide from casein hydrolysate produced by a proteinase from Lactobacillus helveticus CP790.

Casein hydrolysate, produced by an extracellular proteinase from Lactobacillus helveticus CP790, was fractionated by two-step reverse-phase HPLC. Only one fraction showed antihypertensive activity as measured by systolic blood pressure in spontaneously hypertensive rats after oral administration. Ten peptides in the fraction were further purified and identified by analysis of amino acid sequences. Each identified peptide was chemically synthesized, and the antihypertensive activity of each peptide was evaluated in spontaneously hypertensive rats. The synthetic peptide with a sequence of Lys-Val-Leu-Pro-Val-Pro-Gln, found in beta-casein, indicated strong antihypertensive activity from 2 to 10 h after oral administration of 2 mg of peptide/kg of BW, and the effect was maximal at 6 h after oral administration (-31.5 +/- 5.6 mm Hg). Moreover, the antihypertensive effect of the peptide was dependent on the dosage of peptide from 0.5 to 2 mg of peptide/kg of BW. Interestingly, the antihypertensive peptide showed lower inhibitory activity of angiotensin I-converting enzyme, but the activity was increased after pancreatin digestion.

Amino Acid Sequence↗
PubMed1996

Comparative study of pyridoxine-alpha, beta-glucosides, and phosphopyridoxyl-lysine as a vitamin B6 nutrient.

The nutritional effects of pyridoxine-alpha-glucoside (PN-alpha-Glc), pyridoxine-5' beta-glucoside (PN-5' beta-Glc) and epsilon-N-(phosphopyridoxyl)-lysine (PNP-Lys) were examined by means of: 1) transport across the intestinal wall using everted rat intestine, 2) metabolic conversion by liver or kidney homogenate, and 3) oral administration of the compound to B6-deficient rats and the subsequent analysis of B6 derivatives found in plasma. Using everted sacs prepared from rat small intestine, PN-alpha-Glc was transported into the serosal side in its intact form. On the other hand, a part of PN-5' beta-Glc was found as PN on the serosal side (PN-5' beta-Glc: PN = 2:1). When PN-alpha-Glc, PN-5' beta-Glc or PNP-Lys was incubated with liver or kidney homogenate for 3 h at pH 6.0, PN-alpha-Glc was hydrolyzed to PN (6%), while there was no hydrolysis of PN-5' beta-Glc. After 30 min of administration of each B6 derivative to B6-deficient rats, blood was collected from the heart, and the B6-derivatives found in plasma were analyzed. It was ascertained that PN-alpha-Glc served as well as PN as a B6 nutrient, while PN-5' beta-Glc and PNP-Lys were not easily metabolized to the coenzyme form, pyridoxal 5'-phosphate.

Animal Nutritional Physiological Phenomena↗
PubMed1996

[Significance of 123I-metaiodobenzylguanidine SPECT for detecting left ventricular involvement in patients with arrhythmogenic right ventricular dysplasia].

The right ventricle being primarily involved in ARVD, recent reports indicate the presence of histological and functional abnormalities in the left ventricle for some patients with ARVD. The aim of this study was to evaluate the significance of myocardial sympathetic dysfunction as an early sign of left ventricular (LV) involvement by 123I-MIBG (MIBG) SPECT and to compare the findings with those of 201TlCl (Tl) SPECT, radionuclide left ventriculography, ultrafast computed tomography (UFCT), magnetic resonance imaging (MRI) and echo-cardiography in 10 patients (pts) with ARVD. MIBG defects in LV regions were detected in 9 pts. Seven of the 9 pts showed MIBG defects in LV regions adjacent to RV. The subjects were divided into 2 groups based on left ventriculography, 5 with normal LVEF (> 55%) and 5 with reduced LVEF. In the normal LVEF group, 4 pts showed MIBG defects and 2 pts showed TI defects, and MIBG defects were larger than TI defects (ES: 14 +/- 6 vs. 5 +/- 7, p <0.05). In reduced LVEF group, all of 5 pts showed MIBG and TI defects, and MIBG defects were larger than TI defects (ES: 42 +/- 12 vs. 25 +/- 3, p <0.05). In comparison with normal LVEF group, reduced LVEF group showed larger and more severe MIBG defects (ES: 42 +/- 12 vs. 14 +/- 6, p <0.01, SS: 44 +/- 31 vs. 8 +/- 7, p <0.05). UFCT and MRI showed abnormal findings indicating LV fatty infiltration in only 3 of reduced LVEF group. Thus, MIBG showed abnormal distributions in the left ventricle with the highest frequency in all these modalities. These results suggest that MIBG SPECT provides a sensitive marker for detecting LV involvement in ARVD. Also, the extent of MIBG distribution abnormalities is helpful in assessing the severity of left ventricular involvement in patients with ARVD.

3-Iodobenzylguanidine↗
PubMed1995

Gadolinium-enhanced magnetic resonance imaging in acute myocardial infarction.

To investigate the clinical application of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA)-enhanced magnetic resonance imaging (MRI) in the management of acute myocardial infarction (AMI), we examined 44 patients with AMI within 1 month after onset. Enhanced images were classified into 4 types: nontransmural (type 1), transmural and homogeneous (type 2), transmural and marginal (type 3), and no enhancement (type 4). Each enhancement pattern was correlated with angiographic and thallium-201 imaging results. The redistribution images of thallium were graded on a 4-point scale from 0 (normal) to 3 (markedly reduced or absent activity). The percentage of the perimeter affected by asynergy was obtained from the left ventriculogram. Peak creatine kinase and the percentage of asynergic perimeter were significantly higher in type 3 than in other type patients. End-diastolic volume index was significantly higher in type 3 than in type 2 patients. Left ventricular ejection fraction was lowest, and end-systolic volume index, thallium-201 score, and incidence of wall thinning on MRI were highest in type 3 patients. Therefore, the transmural and marginal enhancement pattern (type 3) was compatible with extensive myocardial infarction with infarct expansion and less viable myocardium. In the other types, the infarction was small to moderate in size and left ventricular function was well preserved. Thus, Gd-DTPA-enhanced MRI may be useful in the evaluation of left ventricular function and myocardial viability of the infarct region after AMI.

Aged↗
PubMed1995

Expression of the human interleukin 6 receptor alpha-chain in Xenopus laevis oocytes.

We investigated the biochemical properties of the 80 kDa binding subunit (gp80) of the human interleukin 6 receptor (IL-6R) in the genetic environment of the amphibian Xenopus laevis. In vitro transcribed mRNA encoding full length human gp80 was microinjected into Xenopus laevis stage VI oocytes. Protein expression was monitored by iodinated IL-6 and human gp80-specific monoclonal antibodies (mAb) PM1 and MT18. Maximal IL-6 binding activity was observed between 36-42 h after injection. Scatchard analysis indicated that gp80-injected oocytes expressed two independent classes of IL-6 binding sites of high- (Kd1 = 9 x 10(-11) M, 20 x 10(6) sites/cell) and low-affinity (Kd2 = 2 x 10(-9) M, 70.3 x 10(6) sites/cell). PM1 but not MT18 completely inhibited IL-6 binding to injected eggs. Our data suggest that the human IL-6R alpha-subunit gp80 is sufficient to confer high- and low-affinity IL-6 binding to Xenopus laevis oocytes.

Animals↗
PubMed1995

[Characteristics of regional sympathetic dysfunction in acutely ischemic myocardium assessed by 123I-metaiodobenzylguanidine imaging: impairment of myocardial norepinephrine uptake or retention].

To characterize regional cardiac sympathetic dysfunction due to myocardial ischemia, we examined 123I-metaiodobenzylguanidine (MIBG) myocardial distribution of initial 15-min and 4-hr delayed SPECT images in 14 patients with recent myocardial infarction (MI), 25 patients with vasospastic angina which was angiographically proven with elgonovine maleate (Gp VSAP) and 16 patients with chest pain syndrome and normal CAG findings (GpCP). In those with MI, the study was serially done at 2 weeks after (Gp MI-1) and at 3 months after the onset of MI (Gp MI-2). We estimated regional tracer uptake in 20 segments of tomographic images by using a 4-point scoring system (0 = normal, 1 = mild, 2 = moderate, 3 = severe reduction) and calculated the total defect score (IDS). In all patients with MI, the area of reduced MIBG uptake was more extensive than the 201Tl perfusion defect in the acute stage (Gp MI-1) indicating the presence of viable but denervated myocardial tissue. Also, the MIBG defect was persistently observed from initial (TDS: 24 +/- 13) to delayed imaging (TDS: 26 +/- 12). However, in the chronic stage (Gp MI-2), the initial MIBG uptake improved (TDS: 18 +/- 9) but the delayed uptake remained almost the same (TDS: 22 +/- 10) indicating high washout of MIBG from the ischemic myocardium. Fourteen in Gp VSAP and 14 in Gp CP showed the regional MIBG defect in the delayed image more extensively than in the initial image indicating high washout of MIBG in the involved myocardial regions. These results suggest that neuronal uptake of MIBG is impaired in the acute stage of MI although neuronal retention of MIBG is predominantly impaired in the chronic stage of MI or in Gps VSAP and CP.

3-Iodobenzylguanidine↗
PubMed1994

Myocardial involvement in patients with sarcoidosis. An analysis of 75 patients.

The authors studied 75 nonselected patients (30 men and 45 women; mean age 48 years) with sarcoidosis retrospectively to assess the applicability of nuclear examinations for detecting myocardial involvement. All patients were studied with Tl-201 myocardial perfusion scan (TMPS), Ga-67 myocardial scan (GMS), and left ventricular ejection fraction (LVEF) using ECG-gated radionuclide ventriculography. The positive GMS group had a significantly higher occurrence of abnormality on TMPS (100%) than the negative GMS group (41%). Patients with TMPS abnormality and positive GMS showed significantly lower LVEF (36.3%) than those of normal perfusion or negative GMS. When LVEF decreased, occurrences of TMPS abnormality and positive GMS increased. The authors demonstrate that in patients with sarcoidosis LVEF was closely related to TMPS and GMS, and LVEF reflected the progression of sarcoid heart disease and can be considered a reliable indicator of cardiac function. Patients with sarcoidosis with TMPS abnormality and positive GMS should be thought to have myocardial sarcoidosis and their cardiac functions can be assessed by ECG-gated radionuclide ventriculography, while the remaining patients should be examined with TMPS and GMS periodically for detection of myocardial involvement.

Adult↗
PubMed1994

In vivo monitoring system for structure-function relationship analysis of the antibacterial peptide apidaecin.

A unique antibacterial peptide derivative found in immune honeybee lymph, apidaecin 1b (AP1), was randomly mutagenized and characterized by a newly established system to analyze in vivo its structure-function relationship. Initially, a high-level expression host-vector system for AP1 in Escherichia coli was constructed by creating a fusion protein with the highly stable Streptomyces subtilisin inhibitor (SSI) molecule. Expression of the SSI-AP1 fusion protein was found to depend on the concentration of the transcriptional inducer isopropyl-beta-D-thio-galactopyranoside (IPTG) and to parallel the degree of growth inhibition of the transformant cells. Subsequently, apidaecin derivatives produced by localized random mutagenesis were screened with this IPTG concentration-controlled in vivo system by monitoring the growth inhibition patterns of the transformant cells. One mutant apidaecin (P9L) that had reduced activity was purified and isolated from the periplasmic fraction of an E. coli transformant. Its antibacterial activity was reduced to one-third of that of wild-type apidaecin. When considered together with the other mutations, it was concluded that several Pro residues, including that at the ninth position, are responsible for expression of the antibacterial action of apidaecin.

Amino Acid Sequence↗
PubMed1994

Change in blood levels of vitamin B-6 derivatives in pregnant and lactating rats.

By using an HPLC method which we have developed, concentration changes of vitamin B-6 derivatives in blood of pregnant and lactating rats were studied. PLP and PL were the main derivatives in plasma and erythrocytes, and occasionally, PMP was found in the plasma of rats fed a normal solid diet which contained 8.3 mg PN.HCl/kg diet. Upon pregnancy, the plasma PLP concentration decreased significantly (p < 0.01), whereas plasma PL tended to increase (p < 0.05). PLP concentration in erythrocytes tended to increase upon pregnancy. These results suggest that metabolism or utilization of vitamin B-6 is altered upon pregnancy and that plasma PLP concentrations alone may not be a good indicator of nutritional status. Further confirmation was needed for so from erythrocyte samples under our analytical conditions was not so from erythrocyte samples under our analytical conditions was not converted to PIC-P via PLP, after the sample was treated with glyoxylic acid and then with KCN.

Animals↗
PubMed1993

Characteristics of a 28-kDa collagenous protein extracted with guanidine from EDTA-demineralized rabbit alveolar bone.

Bone proteins in alveolar bone of mandibles from young adult rabbits (3-month-old) were extracted with 4.0 M guanidine hydrochloride (GuHCl), followed by 0.5 M ethylenediaminetetraacetate, and again with 4.0 M GuHCl (G2-ext). The proteins in the G2-ext were fractionated on a gel-filtration column, followed by an anion-exchange column in the presence of 7.0 M urea. A 28-kDa protein was isolated from the G2-ext. The purified 28-kDa protein showed intense staining with silver on SDS-PAGE slab-gel under reducing conditions. This protein was digested with bacterial collagenase, and a 19-kDa fragment appeared on the gel. However, the protein was not susceptible to reduction with cyanogen bromide. The protein did not bind to hydroxyapatite crystals in the presence of 7.0 M urea, and also did not bind to some lectins. On SDS-PAGE under non-reducing conditions, the protein migrated as two bands; a new band appeared at approximately the 85-kDa region in addition to the original 28-kDa band. The amino acid compositions of the protein were similar to those of the alpha 1-pN-propeptide of type I procollagen obtained from other tissues.

Alveolar Process↗
PubMed1993

[The significance of 201Tl/123I MIBG (metaiodobenzylguanidine) mismatched myocardial regions for predicting ventricular tachycardia in patients with idiopathic dilated cardiomyopathy].

123I-MIBG (MIBG) regional defects in myocardial regions with preserved 201Tl (Tl) uptake have been observed in patients with idiopathic dilated cardiomyopathy (DCM). To evaluate whether the presence of Tl/MIBG mismatched regions is related to the occurrence of ventricular tachycardia (VT), we performed myocardial dual SPECT imaging with Tl (111 MBq) and MIBG (111 MBq) in 17 patients with DCM, 11 (Gp A) with and 6 (Gp B) without VT. Myocardial dual SPECT imaging was performed at 15 minutes after and 4 hours after the tracer injection. The regional tracer uptake was scored visually in 6 segments of the basal, middle, and apical short-axial images and in 2 apical segments of the midventricular vertical long-axial image by a four-point scoring system (0 = normal, 1 = moderate, 2 = severe and 3 = complete defect). Then, the severity of tracer maldistributions was assessed by the difference between total defect scores (TDSs) of Tl and MIBG (delta TDS). TDS was not different between Gps A and B in both Tl and MIBG images. However, delta TDS was larger in Gp A than in Gp B (13.5 +/- 6.5 vs. 5.8 +/- 3.0, p < 0.05). Also, the number of segments with the mismatched tracer uptake was larger in Gp A than in Gp B (12.5 +/- 3.0 vs. 8.3 +/- 1.5, p < 0.01). In the electrophysiologic study, we found that the fractionated area corresponded to the mismatched region in 3 of 5 patients in Gp A. These results suggest that regional sympathetic denervation is a possible factor which provocates VT, and myocardial dual SPECT imaging with Tl and MIBG is a useful method for predicting VT in patients with DCM.

3-Iodobenzylguanidine↗
PubMed1992

Extracellular production system of heterologous peptide driven by a secretory protease inhibitor of Streptomyces.

The value of a heterologous peptide extracellular production system in Streptomyces using a secretory protease inhibitor, was examined. DNA was synthesized encoding apidaecin 1b (AP1), an interesting antibacterial peptide discovered in lymph fluid of the honeybee, and was joined to the Streptomyces subtilisin inhibitor (SSI) gene via a 12-bp nucleotide sequence corresponding to the amino acid sequence specific for cleavage by blood coagulation factor Xa. The fusion protein (SSI-AP1) could be expressed and excreted efficiently into the medium by culturing S. lividans 66 harbouring a plasmid vector constructed for SSI secretion, into which the synthetic DNA was introduced. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and amino acid analysis of the purified SSI-AP1 provided reasonable results of molecular size and composition value. Interestingly, SSI-AP1 protein showed bifunctional activity: inhibitory activity of SSI and antibacterial activity of AP1. The inhibitory activity against Escherichia coli could be also detected after the fusion protein was cleaved by factor Xa. The extracellular production system presented here should provide a useful tool for production, analysis of mode of action, and also for genetic improvement of antimicrobial peptides such as apidaecin.

Amino Acid Sequence↗
PubMed1992

Biochemical and immuno- and lectin-histochemical studies of solubility and retention of bone matrix proteins during EDTA demineralization.

The present study utilized biochemical and immuno- and lectin-histochemical methods to demonstrate solubility and retention of mineral-binding non-collagenous proteins in rat midshaft subperiosteal bone during EDTA demineralization. A monoclonal antibody (9-A-2) specific for chondroitin 4-sulphate and dermatan sulphate and wheat germ agglutinin (WGA) specific for N-acetyl-D-glucosamine, N-acetylneuraminic acid, and N-acetyl-D-galactosamine were used. Bone proteins were extracted from fresh unfixed or aldehyde-fixed specimens with a three step extraction procedure, 4 M guanidine HCl (GdnCl), aqueous EDTA without GdnCl, followed by GdnCl. For comparison with the second extraction step, ethanolic trimethylammonium EDTA (ethanolic EDTA) was substituted for aqueous EDTA. Based on protein staining and Western blot analysis of SDS-polyacrylamide gel electrophoresis of each extract using 9-A-2 and WGA, retention of mineral-binding proteins extractable from fresh specimens with aqueous EDTA was greatly increased in tissue when ethanolic EDTA was used. Their retention was even greater with prior aldehyde fixation. Maximum retention with no detectable solubility of 9-A-2 and WGA reactive proteins was obtained after ethanolic EDTA extraction of aldehyde-fixed specimens, which concomitantly provided the strongest immuno- and lectin staining. These results indicate that this combined method dramatically improves retention of PGs and glycoproteins during demineralization of bone tissues and provides the best method for localizing these glycoconjugates.

Acetylgalactosamine↗
PubMed1992

Nature and distribution of mineral-binding, keratan sulfate-containing glycoconjugates in rat and rabbit bone.

The presence of keratan sulfate (KS) and KS proteoglycans in bone has been demonstrated in birds and rabbits but comparison with other animal species has not been investigated. The nature and distribution of mineral-binding, KS-containing glycoconjugates in rat and rabbit bone were investigated with a monoclonal antibody (MAb 5D4) specific for KS. Mineral-binding proteins were extracted from the mineralized bone with 0.4 M EDTA without guanidine-HCl (E-extract). On Western blot analysis of SDS-polyacrylamide gel electrophoresis, rat E-extract gave a weak 5D4-reactive band, M(r) 66,000-68,000, whereas rabbit E-extract produced two major reactive populations of small and large molecular size; one population consisted of two closely spaced bands at M(r) 61,000-63,000 and 66,000-68,000, and the other population consisted of one band at approximately M(r) 200,000. The identity of KS chains was further established by the sensitivity of these bands to keratanase II (Bacillus sp. Ks 36) and endo-beta-galactosidase. Immunocytochemistry with MAb 5D4 showed that, in rat bone, staining associated with the mineral phase was limited to the walls of osteocytic lacunae and bone canaliculi, whereas the remainder of the mineralized matrix lacked staining. In contrast, in rabbit bone the staining was distributed over the entire portion of the mineralized matrix with focal accumulation of staining in the wall of the lacunocanalicular system. These results indicate that rat bone contains a mineral-binding, KS-containing glycoconjugate with preferential localization in the wall of the lacunocanalicular system, whereas rabbit bone contains at least two or possibly three types of KS-containing glycoconjugates distributed over the entire portion of the mineralized matrix.

Animals↗