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Biomedical subjects

M Takeda

Publications and source records attributed to M Takeda.

At least 55 records · Page 3Linked to original sources
PubMed2001

Gene expression and in situ localization of diacylglycerol kinase isozymes in normal and infarcted rat hearts: effects of captopril treatment.

Diacylglycerol (DG) kinase (DGK) terminates signaling from DG, which serves as an activator of protein kinase C (PKC), by converting DG to phosphatidic acid. DGK is thus regarded as an attenuator of the PKC activity. In rats, five DGK isozymes have been cloned, but little is known about their role in the heart. In this study, the spatiotemporal expression of DGK isozymes was investigated in rat hearts under a normal condition and after myocardial infarction (MI) by in situ hybridization histochemistry and immunohistochemistry. In normal left ventricular myocardium, DGKalpha, DGKepsilon, and DGKzeta mRNAs were expressed evenly throughout the myocardium, although the DGKalpha expression was very low. In infarcted hearts, the expression of DGKzeta was enhanced in the peripheral zone of the necrotic area and at the border zone 3 and 7 days after MI, and to a lesser extent in the middle layer of the granulation tissue 21 days after MI. The enhanced DGKzeta expression in the infarcted and border areas could be attributed to granulocytes and macrophages. In contrast, the expression of DGKepsilon in the infarcted and border areas was lower than that in the viable left ventricle (LV) throughout the postoperation period. Furthermore, DGKepsilon expression in the viable myocardium 21 days after MI decreased significantly compared with left ventricular myocardium in the sham-operated rats and was completely restored by treatment with captopril. Our results demonstrate that three DGK isozymes are expressed in the heart and that each isozyme might have different functional characteristics in the healing and LV remodeling after MI.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

Preference for corn oil in olfactory-blocked mice in the conditioned place preference test and the two-bottle choice test.

We studied the effects of olfactory stimuli on preference for corn oil in mice. In the conditioned place preference test, voluntary intake of 100% corn oil by both olfactory normal and ZnSO4-induced olfactory-blocked (anosmic) mice resulted in their place preference for the corn oil-related box. In the olfactory normal mice, place preference was also observed by voluntary intake of linoleic acid as well as of corn oil. In the two-bottle choice test, normal mice showed significant preference for test fluids that contained corn oil at all concentrations (1-10%) tested relative to vehicle alone. However, the lower concentrations (1 and 3%) of corn oil were not preferred in the anosmic mice. These results suggested that stimuli other than olfaction contributed to the rewarding effects of corn oil, but at lower concentrations olfactory stimuli might act as a signal for the oil.

Animals↗
PubMed2001

Modulation of ACh-induced currents in rat adrenal chromaffin cells by ligands of alpha2 adrenergic and imidazoline receptors.

The aim of this study was to investigate the expression of the alpha2-adrenergic receptors in the adrenal medulla, and to examine the mechanism by which clonidine and related drugs inhibit acetylcholine (ACh)-induced whole-cell currents in adrenal chromaffin cells. Reverse transcription-polymerase chain reaction (RT-PCR) performed on punches of rat adrenal medulla demonstrated expression of mRNA for the 2A-, alpha2B- and alpha2C-adrenergic receptors. Similar experiments conducted with tissue punches obtained from the adrenal cortex did not reveal expression of these receptor subtypes. Whole-cell currents were recorded in isolated chromaffin cells using the perforated-patch configuration. ACh (50 microM) evoked inward currents with a peak amplitude of 117.8+/-9.3 pA (n = 45; Vhol = -60 mV). The currents were inhibited in a dose-dependent manner (0.5-50 microM) by clonidine, UK 14,304 and rilmenidine (agonists of alpha2/imidazoline receptors), as well as by SKF 86466 and efaroxan (antagonists). Adrenaline and noradrenaline (50-100 microM) had no significant effect. Thus, although the adrenal medulla expresses mRNA for the alpha2-adrenergic receptors, the lack of agonist-antagonist specificity observed in our whole-cell recordings (in the absence of intracellular dialysis) provides additional evidence against the possibility that these inhibitory effects are mediated by classical alpha2 or imidazoline receptor interactions.

Acetylcholine↗
PubMed2001

Characterization of organic anion transport inhibitors using cells stably expressing human organic anion transporters.

The organic anion transport system is involved in the tubular excretion of various clinically important drugs. The purpose of this study was to characterize the effects of various organic anion transport inhibitors on organic anion transport using proximal tubule cells stably expressing human organic anion transporter 1 (human-OAT1) and human-OAT3, which are localized to the basolateral membrane of the proximal tubule. Organic anion transport inhibitors including betamipron, cilastatin, KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine) and probenecid significantly inhibited human-OAT1- and human-OAT3-mediated organic anion uptake in a dose-dependent manner. Kinetic analyses revealed that these inhibitions were competitive. The Ki values of betamipron, cilastatin, KW-3902 and probencid for human-OAT1 were 23.6, 1470, 7.82 and 12.1 microM, whereas those for human-OAT3 were 48.3, 231, 3.70 and 9.0 microM. These results suggest that betamipron and probenecid could inhibit both human-OAT1- and human-OAT3-mediated organic anion transport in vivo, whereas cilastatin could inhibit only human-OAT3-mediated one. In contrast, KW-3902 did not exert the effects of significance, whereas KW-3902 was the most potent.

Alanine↗
PubMed2001

Expression of mouse igf2 mRNA-binding protein 3 and its implications for the developing central nervous system.

Functional analyses of neural RNA-binding proteins have focused mainly on their roles as modulators of posttranscriptional gene regulation, e.g., alternative splicing, dendritic mRNA localization, and local translation. Here we identified a mouse homologue of human IMP3, which is known to bind to and repress the translation of igf2 leader 3 mRNA. The mouse igf2 mRNA-binding protein 3 (mIMP3) is a member of the zipcode binding protein-1 (ZBP-1) family previously reported in chick fibroblast cells. mIMP3 was expressed in undifferentiated neuroepithelial cells and some postmitotic neurons at early embryonic stages (E10.5--E12.5), and its expression level decreased after the midembryonic stage (E12.5) until birth. The expression profile of mIMP3 is very similar to that of mouse igf2 leader 3 mRNA. In vitro UV cross-linking experiments showed that mIMP3 preferentially bound to igf2 leader 3 mRNA rather than igf2 leader 4 mRNA and did not bind the zipcode region of beta-actin or c-myc mRNA. Furthermore, persistent expression of mIMP3 protein in an undifferentiated P19 cell line revealed that mIMP3 inhibited neuronal differentiation morphologically and immunohistochemically. Taken together, these observations raise the possibility that mIMP3 represses neuronal differentiation through the regulation of igf2 mRNA expression.

5' Untranslated Regions↗
PubMed2001

Differential expression of catecholamine biosynthetic enzymes in the rat ventrolateral medulla.

Adrenergic (C1) neurons located in the rostral ventrolateral medulla are considered a key component in the control of arterial blood pressure. Classically, C1 cells have been identified by their immunoreactivity for the catecholamine biosynthetic enzymes tyrosine hydroxylase (TH) and/or phenylethanolamine N-methyltransferase (PNMT). However, no studies have simultaneously demonstrated the expression of aromatic L-amino acid decarboxylase (AADC) and dopamine beta-hydroxylase (DBH) in these neurons. We examined the expression and colocalization of all four enzymes in the rat ventrolateral medulla using immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Retrograde tracer injected into thoracic spinal segments T2-T4 was used to identify bulbospinal neurons. Using fluorescence and confocal microscopy, most cells of the C1 group were shown to be double or triple labeled with TH, DBH, and PNMT, whereas only 65-78% were immunoreactive for AADC. Cells that lacked detectable immunoreactivity for AADC were located in the rostral C1 region, and approximately 50% were spinally projecting. Some cells in this area lacked DBH immunoreactivity (6.5-8.3%) but were positive for TH and/or PNMT. Small numbers of cells were immunoreactive for only one of the four enzymes. Numerous fibres that were immunoreactive for DBH but not for TH or PNMT were noted in the rostral C1 region. Single-cell RT-PCR analysis conducted on spinally projecting C1 neurons indicated that only 76.5% of cells that contained mRNA for TH, DBH, and PNMT contained detectable message for AADC. These experiments suggest that a proportion of C1 cells may not express all of the enzymes necessary for adrenaline synthesis.

Animals↗
PubMed2001

Molecular evidence for two vitellogenin genes and processing of vitellogenins in the American cockroach, Periplaneta americana.

The American cockroach, Periplaneta americana has two vitellins (Vn1 and Vn2) and corresponding vitellogenins (Vg1 and Vg2). Vns/Vgs were separated on the SDS-PAGE as three major polypeptide bands [170, 100 (multisubunits), and 50 kD] and a minor polypeptide band (150 kD) both in the egg (mature terminal oocyte) extract and in the female hemolymph. We previously cloned one Vg (Vg1) cDNA and showed that the 170-kD polypeptide originated from the C-terminus of the Vg1. In the present study, we cloned the other Vg (Vg2) cDNA. It is 5,826 bp long encoding 1,876 amino acid residues (including 16 residues for putative signal peptide) in a single ORF. The deduced amino acid sequences of both Vgs (Vg1 and Vg2) of P. americana showed 30% identity. The GL/ICG motif is followed by eight cysteine residues at conserved locations near the C-terminal and the DGXR motif starts 18 residues upstream of the GL/ICG motif. The chemically determined N-terminal amino acid sequences of the 150-kD and of the 50-kD polypeptides matched exactly with each other and with the deduced N-terminal amino acid sequence of the Vg2 cDNA. The pattern of processing in P. americana Vns/Vgs is discussed.

Amino Acid Motifs↗
PubMed2001

Pharmacotherapy of Alzheimer's disease: is there a need to redefine treatment success?

The traditional aim of Alzheimer's disease treatment in clinical trials has been to improve cognitive abilities. It has become increasingly clear, however, that other aspects are important in assessing treatment responses. A group of 10 physicians recently gathered to review the current criteria for assessing treatment success in Alzheimer's disease. While cognition has been previously viewed as the primary measure of efficacy, areas such as functional abilities, behaviour, caregiver burden, quality of life and resource utilization all need to be comprehensively assessed to fully evaluate treatment effects in patients with Alzheimer's disease, as well as their impacts on caregivers and society. Postponing or slowing decline in any of these areas may represent an important benefit and should be considered as an outcome measure in clinical trials, clinical practice and decision-making about healthcare budgets. Accepted instruments are available for assessing outcomes in each aspect of Alzheimer's disease, but they need to be selected carefully to provide valid, meaningful data. Some of the most frequently used outcome measures in Alzheimer's disease are reviewed. Using expanded criteria for treatment success and clinically relevant outcome measures, data from currently available studies show that cholinesterase inhibitors produce clinically meaningful long-term benefits in multiple domains in patients with Alzheimer's disease.

Activities of Daily Living↗
PubMed2001

Cockroach midgut peptides that regulate cell proliferation, differentiation, and death in vitro.

The number of insect midgut cells is maintained homeostatically in vivo and in vitro. However, during starvation, the midgut shrinks and the rate of cell replacement appears to be suppressed. When they undergo metamorphosis, the internal organs of insects are drastically remodeled by cell proliferation, differentiation, and apoptotic processes, and the net number of cells usually increases. An extract of 1650 midguts of Periplaneta americana was fractionated by high-performance liquid chromatography (HPLC) to obtain the peptides that regulate these processes. The HPLC fractions were tested for myotropic activity in the foregut and for effects on cell proliferation or loss in primary cultures of larval Heliothis virescens midgut cells and in a cell line derived from the last-instar larval fat body of Mamestra brassicae. Some fractions stimulated midgut stem cell proliferation and differentiation, while others caused loss of differentiated columnar and goblet cells. Other fractions stimulated cell proliferation in the larval fat body cells.

Animals↗
PubMed2001

Control of life, death, and differentiation in cultured midgut cells of the lepidopteran, Heliothis virescens.

Differentiated cells in the insect midgut depend on stem cells for renewal. We have immunologically identified Integrin beta1, a promotor of cell-cell adhesion that also induces signals mediating proliferation, differentiation, and apoptosis on the surfaces of cultured Heliothis virescens midgut cells; clusters of immunostained integrin beta1-like material, indicative of activated integrin, were detected on aggregating midgut columnar cells. Growth factor-like peptides (midgut differentiation factors 1 and 2 [MDF1 and MDF2]), isolated from conditioned medium containing Manduca sexta midgut cells, may be representative of endogenous midgut signaling molecules. Exposing the cultured midgut cells to Bacillus thuringiensis (Bt) toxin caused large numbers of mature differentiated cells to die, but the massive cell death simultaneously induced a 150-200% increase in the numbers of midgut stem and differentiating cells. However, after the toxin was washed out, the proportions of cell types returned to near-control levels within 2 d, indicating endogenous control of cell-population dynamics. MDF1 was detected immunologically in larger numbers of Bt-treated columnar cells than controls, confirming its role in inducing the differentiation of rapidly produced stem cells. However, other insect midgut factors regulating increased proliferation, differentiation, as well as inhibition of proliferation and adjustment of the ratio of cell types, remain to be discovered.

Animals↗
PubMed2001

Constitutive nitric oxide synthase is associated with retinal vascular permeability in early diabetic rats.

AIMS/HYPOTHESIS: We investigated the association between vascular permeability and constitutive nitric oxide synthase in rats with diabetes for a short duration (2 weeks). METHODS: Retinal vascular permeability was evaluated in rats with diabetes induced by streptozotocin using vitreous fluorophotometry and a small animal adapter. We carried out in situ hybridization and semi-quantitative reverse transcription-polymerase chain reaction to study the expression of endogenous constitutive nitric oxide synthase mRNA in diabetic retinas. We also examined changes in the protein expression of constitutive nitric oxide synthase in diabetic retinas using immunohistochemistry and Western blotting. RESULTS: Retinal vascular permeability was significantly higher in diabetic rats (median, 1.09 arbitrary unit) compared with control rats (median, 0.69 arbitrary unit) (p < 0.05). The expression of both neuronal nitric oxide synthase (NOS) and endothelial nitric oxide synthase mRNA was higher in diabetic retinas than in the retinas of control rats as determined by in situ hybridization and reverse transcription-polymerase chain reaction. Immunohistochemistry and Western blotting also showed that neuronal nitric oxide synthase increased in diabetic retinas. The immunohistochemistry of endothelial nitric oxide synthase indicated that non-vessel tissues increased in diabetic retinas while retinal vessels weakened. Western blotting showed that the amount of endothelial nitric oxide synthase increased. CONCLUSION/INTERPRETATION: These results suggest that increases in both constitutive NOSs (nNOS and eNOS) could be associated with retinal vascular permeability and that NOS is associated with clinical vascular dysfunction in the early stages of diabetes.

Animals↗
PubMed2001

Transforming growth factor beta production by spontaneous malignant mesothelioma cell lines derived from Fisher 344 rats.

We investigated whether transforming growth factor beta (TGF-beta) is involved in the growth of malignant mesothelioma (MM) cells in culture. TGF-beta production was examined in two mesothelioma cell lines (MeET-4 and -6) that were established from rat spontaneous MM in our laboratory. TGF-beta bioactivity in conditioned medium of these cell lines was analyzed using a CCL64 mink lung epithelial cell growth inhibition assay and found to be 30-70 times higher than that of normal rat mesothelial cells (MCs). The MM cell lines also showed considerably higher levels of TGF-beta mRNA expression when compared with MCs. The bioactivity and mRNA expression level were greater in MeET-4 than MeET-6. When MeET-4 was treated with antisense TGF-beta1 oligonucleotide (ODN), a significant decrease in both anchorage-dependent and -independent growth was observed. Treatment with exogenous TGF-beta resulted in no effects on the growth pattern of the MM cell lines, while proliferation of the MCs was slightly induced. It is considered that TGF-beta appears to be produced by rat spontaneous MM cells through an autocrine mechanism and could modulate the malignant growth of the tumor cells.

Animals↗
PubMed2001

A comparative study of an olfactory epithelial area lacking olfactory neurons and a nearby presence of TGF-alpha-like immunoreactive olfactory neurons.

Our previous study has shown that ddY mice have special patches of nasal epithelium in the posterior roof of the nasal cavity that exclusively consists of olfactory supporting cells and horizontal basal cells. Here, we extend this finding to Balb/c and DBA/2 mice, Wistar and Sprague-Dawley rats, hamsters, and guinea pigs. In the mice, rats, and hamsters studied, the patches lacked olfactory cells and their precursor, globose basal cells. In rats and hamsters, the supporting cells were arranged in a single layer, in mice as three or four layers. Horizontal basal cells were located in a single layer in these species. In the guinea pigs, the specialized roof structure was less clear and could be seen at the level of ultrastructure as an olfactory neuron-lacking area. Distinct populations of transforming growth factor (TGF)-alpha-like immunoreactive olfactory cells occupied an area close to the epithelial patches. In this region, the TGF-alpha-like immunoreactive neurons were negative for the usual olfactory markers, either OMP or protein gene product (PGP) 9.5 or beta-tubulin. These cells are suggested to project to the so-called 'necklace glomeruli' and use a different cGMP-driven, transduction pathway. Three-dimensional analysis of double-labeled (TGF-alpha, PGP9.5) serial sections revealed a unique relation among the epithelial patches, TGF-alpha-like immunoreactive neurons and olfactory epithelium.

Animals↗
PubMed2001

Immunoelectron-microscopic study of Kit-expressing cells in the jejunum of wildtype and Ws/Ws rats.

Interstitial cells of Cajal (ICC) are responsible for generating electrical slow waves in the gastrointestinal (GI) tract. Slow waves regulate the frequency of contractions of the tunica muscularis, and therefore ICC are critical for normal motility in the small intestine. ICC express Kit, the gene product of c-kit, a protooncogene that encodes a receptor tyrosine kinase. Physiological evidence demonstrating that ICC are pacemakers has come from experiments on W-mutant mice which have few Kit-positive cells at the level of the myenteric plexus (IC-MY) and also lack electrical slow waves. In the past identification of ICC required the use of electron microscopy, however the discovery that ICC express Kit has facilitated studies of the distribution of ICC in several species. Immunoelectron microscopy to relate ultrastructure to Kit expression has only been performed in a limited number of studies of mice. We examined the ultrastructure of Kit-expressing cells in the rat using immunoelectron microscopy and an anti-Kit antibody. We compared the presence and appearance of Kit-expressing ICC in wildtype and Ws/Ws rats, which carry a mutation in the white spotting locus and have a phenotype similar to W/Wv mutant mice. Kit-expressing cells could be detected in the myenteric plexus (MY) and deep muscular plexus (DMP) regions of the small intestine of wildtype animals. In Ws/Ws rats, Kit-expressing cells were not observed in the region of MY, but were observed in the DMP. The density of Kit-positive cells in the DMP of Ws/Ws rats was similar to those in wildtype rats. Electron microscopy showed that Kit-expressing cells at the level of the MY of the rat had similar ultrastructural features as IC-MY in wildtype mice. IC-DMP in the rat of both wildtype and Ws/Ws mutants were similar in structure to IC-DMP of the mouse. We conclude that wildtype rats have IC-MY and IC-DMP in the tunica muscularis of the jejunum. ICC express Kit-like immunoreactivity (Kit-LI) in the rat as in the mouse. IC-MY are absent in the small intestine of Ws/Ws rats, and this corresponds to the lack of Kit-labeling in this region. Ws/Ws rats, however, possess IC-DMP with normal ultrastructural features and Kit-LI. The absence of IC-MY of Ws/Ws rats is likely to account for the abnormal contractile activity of the GI tract observed in these mutants. The present study suggests that Ws/Ws rats could provide an interesting model to investigate the physiological significance of pacemaker activity because they manifest a defect in IC-MY.

Animals↗
PubMed2001

Effect of vagal afferent conditioning on trigeminal motor neuron activity associated with tooth-pulp-evoked jaw-opening reflex.

To clarify the vagal afferent modifying effect on the neurons constituting the nociceptive jaw-opening reflex (JOR), we conducted extracellular recording of trigeminal motor nucleus (TMN) neuron activity in pentobarbital-anesthetized rats. Of 12 TMN neuron responses evoked by tooth pulp (TP) stimulation, 10 were suppressed by vagal afferent conditioning (83%). The mean time of the suppressive effect on the TMN neurons paralleled that found with the digastric electromyogram (dEMG), and maximal inhibition of both TMN neuronal spikes and the dEMG amplitude were observed at a 50-ms conditioning-test interval. The ratio of inhibition was approximately 38%. Seven of 12 units were activated antidromically by digastric muscle stimulation (1-3 mA, 0.1 ms, 2 Hz) and fulfilled the criteria for antidromic activation. Vagal afferent conditioning stimulation had no effect on the antidromic TMN neuronal responses to digastric muscle stimulation. These results suggest that suppression of the TP-evoked JOR in response to vagal afferent stimulation in rats is the result of an inhibitory effect on the sensory neurons rather than on the motor neurons.

Journal Article↗
PubMed2001

Inhibitory effect of losartan on laser-induced choroidal neovascularization in rats.

PURPOSE: To investigate the inhibitory effects of losartan, an angiotensin receptor antagonist, on angiogenesis in a rat model of laser-induced choroidal neovascularization. METHODS: Experimental study. Fifteen Brown-Norway male rats received losartan (approximately 5 mg/kg/d) in drinking water, and 15 Brown-Norway male rats received unsupplemented drinking water 1 week before photocoagulation, and it was continued to the end of the study. Two weeks after intense laser photocoagulation, choroidal neovascularization was evaluated by fluorescein angiography and histopathologic evaluation. RESULTS: The incidence of choroidal neovascularization formation was 99.5 +/-.2% (mean +/- standard deviation) in controls and 72.5 +/- 8.8% in losartan-treated rats (P <.01). Quantitative morphometric assessment revealed mean choroidal neovascularization lesion thickness of 54 and 44.8 microm, respectively, in controls and losartan-treated rats (P <.01). CONCLUSION: Losartan seems to inhibit development of laser-induced choroidal neovascularization. Angiotensin receptor antagonists may be useful as prophylaxis against choroidal neovascularization associated with age-related macular degeneration.

Angiotensin Receptor Antagonists↗