Biomedical subjects
Publications and source records attributed to H Ohta.
Post-traumatic syringomyelia is estimated to develop in more than 20% of individuals with traumatic spinal cord injury (SCI). The development can give rise to clinical symptoms 6 months to 26 years after the injury, and presentation 40 years post-injury has been seen by one of the authors.1234 We present an unusual case for comments and discussion.
BACKGROUND: Retinoid X receptors RXRalpha, beta and gamma exert multiple functions in the genetic regulation of mammalian signalling systems by forming heterodimeric complexes with several nuclear ligand receptors. In contrast to the widespread expression of RXRalpha and RXRbeta, the expression of RXRgamma is restricted to particular tissues in which RXRgamma1 is the major isoform expressed in the mouse corpus striatum. RESULTS: To investigate the function of this particular isoform RXRgamma1, we generated RXRgamma1 gene-knockout mice by homologous recombination in ES cells. Both heterozygous and homozygous mice showed severe runting after birth, which often resulted in the early death of mice of the 129/C57BL-6 genetic background. Independent of genetic background, however, the expression of choline acetyltransferase (ChAT) in the cholinergic interneurones in the striatum (caudal putamen) was markedly reduced in the RXRgamma1 gene-null mice. Furthermore, the mutant exhibited an altered response to the administration of dopamine receptor antagonists, haloperidol and chlorpromazine, which normally induce catalepsy in mice. CONCLUSIONS: These results strongly suggest that RXRgamma1 plays an important role in either the development or activation of cholinergic neurones in nigrostriatal extrapyramidal pathways.
The Polycomb group of (PcG) genes were originally described in Drosophila, but many PcG genes have mammalian homologs. Genetic studies in flies and mice show that mutations in PcG genes cause posterior transformations caused by failure to maintain repression of homeotic loci, suggesting that PcG proteins have conserved functions. The Drosophila gene Sex comb on midleg (Scm) encodes an unusual PcG protein that shares motifs with the PcG protein polyhomeotic, and with a Drosophila tumor suppressor, lethal(3)malignant brain tumor (l(3)mbt). Expressed sequence tag (EST) databases were searched to recover putative mammalian Scm homologs, which were used to screen murine cDNA libraries. The recovered cDNA encodes two mbt repeats and the SPM domain that characterize Scm, but lacks the cysteine clusters and the serine/threonine-rich region found at the amino terminus of Scm. Accordingly, we have named the gene Sex comb on midleg homolog 1 (Scmh1). Like their Drosophila counterparts, Scmh1 and the mammalian polyhomeotic homolog RAE28/mph1 interact in vitro via their SPM domains. We analyzed the expression of Scmh1 and rae28/mph1 using northern analysis of embryos and adult tissues, and in situ hybridization to embryos. The expression of Scmh1 and rae28/mph1 is well correlated in most tissues of embryos. However, in adults, Scmh1 expression was detected in most tissues, whereas mph1/rae28 expression was restricted to the gonads. Scmh1 is strongly induced by retinoic acid in F9 and P19 embryonal carcinoma cells. Scmh1 maps to 4D1-D2.1 in mice. These data suggest that Scmh1 will have an important role in regulation of homeotic genes in embryogenesis and that the interaction with RAE28/mph1 is important in vivo.
MGDG synthase, the enzyme that catalyzes the synthesis of the major chloroplast membrane lipid monogalactosyldiacylglycerol (MGDG), is encoded by a multigenic family. We have analyzed the biochemical properties, subcellular localization and membrane topology of a spinach chloroplast MGDG synthase, a representative member of the type A family from Spinacia oleracea (soMGD A), using a recombinant protein that was functionally overexpressed in Escherichia coli and specific polyclonal antibodies. We demonstrated that soMGD A could catalyze the synthesis of both 'prokaryotic' and 'eukaryotic' MGDG molecular species in vitro, with a selectivity for diacylglycerol similar to that of purified chloroplast envelope MGDG synthase activity. Furthermore, soMGD A was shown to be sensitive to chemical reagents (dithiothreitol, N-ethylmaleimide and o-phenanthroline) known to affect MGDG synthesis by the partially purified enzyme, as well as in isolated chloroplast envelope membranes. In spinach chloroplasts, soMGD A was localized by Western blot analysis in the inner envelope membrane. Topological studies demonstrated that soMGD A is a monotopic enzyme, embedded within one leaflet of the inner envelope membrane from spinach chloroplasts, a structure which may involve amphipathic alpha helices. We further demonstrated that in vitro, soMGD A precursor is imported and processed to its correct mature form in intact chloroplasts. These results show that soMGD A corresponds to a mature polypeptide of approximately 45 kDa. In addition, inactivation kinetics after gamma-ray irradiation strongly suggest that both native chloroplast envelope MGDG synthase and recombinant soMGD A have a functional molecular mass of 95-100 kDa, indicating that they are probably active as homodimers made of two 45-kDa subunits. This study suggests that, in spite of the growing evidence that MGDG synthesis is catalyzed by a multigenic family of enzymes, in spinach leaves both prokaryotic and eukaryotic MGDG syntheses could be attributable to a unique dimeric enzyme, provided that diacylglycerol is transported from the outer membrane to the inner membrane of the chloroplast envelope.
A case of mucinous cholangiocarcinoma (CC), a rare histological type of CC, featuring unusual images is reported. The patient was hospitalized because of acute development of jaundice and fever. Computed tomography demonstrated multiple cystic lesions in the liver and a band-like low density area parallel to the intrahepatic portal vein, a so-called 'periportal collar'. Endoscopic cholangiography revealed a stricture of the hepatic duct with slight upstream dilatation. Cytology of the bile juice and fine-needle aspiration of the cystic lesion in the liver disclosed mucinous carcinoma. The patient died of multiorgan failure 3 weeks after admission. The autopsied liver showed that multiple mucus lakes were lined with adenocarcinoma cells and signet ring cells were floating in the mucus lakes. The cancer cells had spread along the portal tract and invaded into the hepatic parenchyma.
Through about 130 years of the history of experimental aesthetics, preferences of figures have been summarized in representative values such as the golden ratio. Researches especially in the golden-section hypothesis overshadowed the basic and profound problem of how people's individual preference would be decided. In the present study I returned to simple quadrangles, and investigated each person's subjective preferences by a production method, recording eye movements, and having qualitative interviews. Two basic scanning patterns on quadrangles emerged through the analysis of eye movements, and more complicated patterns were made by various combinations of these two. The distribution of subjects' preferred proportions showed that squares and square-like quadrangles were chosen most frequently, although the average of height/width ratios came close to the golden ratio in most quadrangle types. The results of interviews revealed various characteristics of decision processes of preferred shapes in the subjects. A discussion is provided on dealing with the golden ratio, and the importance of studying subjects' processes of preferences is proposed for the future of empirical aesthetics.
1H, 13C, and 15N NMR resonances of the SH2 domain of Grb2/Ash in both the free form and the form complexed with a phosphotyrosine-containing peptide derived from the EGF receptor were assigned by analysis of multi-dimensional, double- and triple-resonance NMR experiments. From the chemical shift changes of individual residues upon peptide binding, the binding site for the peptide was mapped on the structure of Grb2/Ash SH2. The peptide was not recognized by the groove formed by the BG and EF loops, suggesting that the EGFR peptide does not bind to Grb2/Ash SH2 in an extended conformation. This was supported by analysis of the binding affinity of mutants where residues on the BG and EF loops were changed to alanine. The present results are consistent with the recently reported structures of Grb2/Ash SH2 complexed with BCR-Abl and Shc-derived phosphotyrosine containing peptides, where the peptide forms a turn conformation. This shows that the specific conformation of the phosphotyrosine-containing sequence is required for the SH2 binding responsible for downstream signaling.
Glucosyltransferase-I (GTF-I: 175 kDa) of a cariogenic bacterium, Streptococcus sobrinus 6715, mediates the conversion of water-soluble dextran (alpha-1,6-glucan) into a water-insoluble form by making numerous alpha-1,3-glucan branches along the dextran chains with sucrose as the glucosyl donor. The structures and catalytic properties were compared for two GTF-I fragments, GTF-I' (138 kDa) and GS (110 kDa). Both lack the N-terminal 84 residues of GTF-I. While GTF-I' still contains four of the six C-terminal repeats characteristic of streptococcal glucosyltransferases, GS lacks all of them. Electron microscopy of negatively stained samples indicated a double-domain structure for GTF-I', consisting of a spherical head with a smaller spherical tail, which was occasionally seen as a long extension. GS was seen just as the head portion of GTF-I'. In the absence of dextran, both fragments simply hydrolyzed sucrose with similar K(m) and k(cat) values at low concentrations (<5 mM). At higher sucrose concentrations (>10 mM), however, GTF-I' exhibited glucosyl transfer activity to form insoluble alpha-1, 3-glucans. So did GS, but less efficiently. Dextran increased the rate and efficiency of the glucosyl transfer by GTF-I'. On removal of the C-terminal repeats of GTF-I' by mild trypsin treatment, this dextran-stimulated transfer was completely lost and the dextran-independent transfer became less efficient. These results indicate that the N-terminal two-thirds of the GTF-I sequence are organized as a structurally and functionally independent domain to catalyze not only sucrose hydrolysis but also glucosyl transfer to form alpha-1,3-glucan chains, although not efficiently; the C-terminal repeat increases the efficiency of the intrinsic glucosyl transfer by the N-terminal domain as well as rendering the whole molecule primer-dependent for far more efficient insoluble glucan synthesis.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Cytotoxic necrotizing factor types 1 and 2 (CNF1 and -2) produced by pathogenic Escherichia coli strains have 90% conserved residues over 1,014-amino-acid sequences. Both CNFs are able to provoke a remarkable increase in F-actin structures in cultured cells and covalently modify the RhoA small GTPases. In this study, we demonstrated that CNF2 reduced RhoA GTPase activity in the presence and absence of P122(RhoGAP). Subsequently, peptide mapping and amino acid sequencing of CNF2-modified FLAG-RhoA produced in E. coli revealed that CNF2 deamidates Q63 of RhoA-like CNF1. In vitro incubation of the C-terminal domain of CNF2 with FLAG-RhoA resulted also in deamidation of the FLAG-RhoA, suggesting that this region contains the enzymatic domain of CNF2. An oligopeptide antibody (anti-E63) which specifically recognized the altered G-3 domain of the Rho family reacted with glutathione S-transferase (GST)-RhoA and GST-Rac1 but not with GST-Cdc42 when coexpressed with CNF2. In addition, CNF2 selectively induced accumulation of GTP form of FLAG-RhoA and FLAG-Rac1 but not of FLAG-Cdc42 in Cos-7 cells. Taken together, these results indicate that CNF2 preferentially deamidates RhoA Q63 and Rac1 Q61 and constitutively activates these small GTPases in cultured cells. In contrast, anti-E63 reacted with GST-RhoA and GST-Cdc42 but not with GST-Rac1 when coexpressed with CNF1. These results indicate that CNF2 and CNF1 share the same catalytic activity but have distinct substrate specificities, which may reflect their differences in toxic activity in vivo.
In vitro studies have shown that ipriflavone affects both bone formation and bone resorption, but the effect in early-stage postmenopausal women with low bone mass and a high turnover of bone metabolism is unknown. In this prospective study, we randomly assigned 60 patients with postmenopausal osteopenia or osteoporosis to receive either 600 mg/day of ipriflavone or 0.8 g/day calcium lactate, and compared the effects on bone mineral density (BMD) from the 2nd to 4th lumbar vertebrae (L2-4) and bone metabolic markers before and after one year of treatment. In the iprifravone-treated (IP) group, L2-4 BMD was similar before and after treatment (0.78 and 0.77 g/cm(2), respectively), but in the calcium lactate-treated (CL) group, L2-4 BMD decreased significantly from 0.81 to 0.79 g/cm(2) after 1 year of treatment (p < 0.0001). Furthermore, the rate of the decrease in L2-4 BMD was significantly greater in the CL group than in the IP group (p < 0.01). The median deoxypyridinoline (Dpd) level was significantly lower after 1 year of treatment (5.8 mmol/mmol creatinine [Cr]) than the baseline value (10.2 mmol/mmol Cr) in the IP, but not in the CL group, suggesting that IP treatment suppresses bone resorption.
The purpose of the present experiment was to study the pathophysiological roles of endothelin-1 (ET-1) in salt-sensitive hypertension with the use of Dahl salt-sensitive (DS) and salt-resistant (DR) rats. PreproET-1 mRNA expression was determined by reverse transcription-polymerase chain reaction. In the kidney, expression of preproET-1 mRNA was greater in DS rats on a normal salt diet compared with DR rats of the same age. In DS rats, the level of preproET-1 mRNA expression in kidney had a significant correlation with systolic blood pressure. The expression of preproET-1 mRNA in aorta and kidney was increased by 3-week high salt intake in DS rats but not in DR rats. Expression of preproET-1 mRNA and ET-1 levels in left ventricle was exaggerated by high salt intake in DS rats. However, there was no significant difference in plasma ET-1 levels between DS and DR rats regardless of salt intake. Pressor response curves for ET-1 in DS rats with or without high salt intake were significantly shifted to the left compared with those in DR rats. A single oral dose (3 to 10 mg/kg) of J-104132 (L-753 037), a potent, orally active mixed endothelin A and B (ET(A)/ET(B)) receptor antagonist, reduced blood pressure to normotensive levels in DS rats with high salt intake, and its action was maintained for >/=24 hours. In DS rats with normal salt intake, J-104132 (10 mg/kg) slightly but significantly decreased blood pressure. DR rats did not show obvious depressor responses to J-104132 (10 mg/kg) regardless of salt intake. These results suggest that ET-1 acts as one of the pathophysiological factors in the development and maintenance of salt-sensitive hypertension, and a mixed ET(A)/ET(B) receptor antagonist could be useful in the treatment for salt-sensitive hypertension.
Losartan is the first orally active angiotensin II receptor type 1 antagonist for a new class of cardiovascular therapeutic agent. Losartan is converted to an active metabolite (E3174) after oral administration in humans and rats. Both losartan and E3174 contribute to the net angiotensin II receptor blockade and produce anti-hypertensive effect. Losartan not only blocks the vasoconstrictive effect of angiotensin II but also inhibits its mitogenic effect; thus losartan is expected to protect against end-organ-damage-related hypertension and chronic heart failure. Unlike angiotensin-coverting-enzyme inhibitor, losartan does not elicit adverse effects of cough and angioneurotic edema by its blockade of angiotensin II receptor. It is also expected to reduce proteinuria in nephropathy. In addition to its blockade of angiotensin II receptor, losartan blocks thromboxane A2 receptor and facilitates excretion of uric acid, although therapeutic importance of these effects are under investigation. In summary, losartan, an angiotensin II type 1 receptor antagonist is a new class of antihypertensive agent and its therapeutic potentials are not merely reduction of blood pressure but total protection from end-organ damage resulting from activation of both the systemic and local renin-angiotensin system.
The aim of the present study was to establish a useful animal model that simulates humans sensitive to inhaled particulate matter (PM). We have developed a new rat model of acute bronchiolitis (Br) by exposing animals to NiCl2 (Ni) aerosols for five days. Three days following the Ni exposure, the animals developed signs of tachypnea, mucous hypersecretion, and bronchiolar inflammation which seemed to progress quickly during the fourth to fifth day. They recovered from lesions after four weeks in clean air. To assess the sensitivity of the Br rats to inhaled particles, two kinds of PM of respirable size were tested with doses similar to or a little higher to the recommended threshold limit values (TLVs) for the working environment in Japan. Titanium dioxide (TiO2 = Ti) was chosen as an inert and insoluble particles and vanadium pentoxide (V2O5 = V), as a representative soluble and toxic airborne material. The Br rats exposed to either Ti or V were compared the pathological changes in the lungs and the clearance of particles to those in normal control or Br rats kept in clean air. The following significant differences were observed in Br rats: 1. delayed recovery from pre-existing lesions or exacerbated inflammation, 2. reductions in deposition and clearance rate of inhaled particles with the progress of lesions. The present results suggest that Br rats are more susceptible to inhaled particles than control rats. Therefore, concentrations of particulate matter lower than the TLVs for Japan, which have no harmful effects on normal lungs, may not always be safe in the case of pre-existing lung inflammation.
J-104132 [(+)-(5S,6R, 7R)-2-butyl-7-[2-((2S)-2-carboxypropyl)-4-methoxyphenyl]-5-(3, 4-methylenedioxyphenyl)cyclopenteno[1,2-b]pyridine-6-carboxylic; also referred to as L-753,037] is a potent, selective inhibitor of ETA and ETB endothelin (ET) receptors (e.g., Ki: cloned human ETA = 0.034 nM; cloned human ETB = 0.104 nM). In both ligand-binding and isolated tissue preparation protocols, the inhibition of ET receptors with J-104132 is reversible and competitive. In vitro, J-104132 is a potent antagonist of ET-1-induced accumulation of [3H]inositol phosphates in Chinese hamster ovary cells stably expressing cloned human ETA receptors (IC50 = 0.059 nM), ET-1-induced contractions in rabbit iliac artery (pA2 = 9.70) and of BQ-3020-induced contractions in pulmonary artery (pA2 = 10.14). J-104132 is selective for ET receptors because it had no effect on contractions elicited by norepinephrine or KCl in the vascular preparations. The in vivo potency of J-104132 was assessed using challenges with exogenous ET-1. In conscious mice, 5 nmol/kg i.v. ET-1 causes death. Pretreatment with J-104132 prevents the lethal response to ET-1 when administered i.v. (ED50 = 0.045 mg/kg) or p.o. in fed animals (ED50 = 0.35 mg/kg). In conscious, normotensive rats, pressor responses to 0.5 nmol/kg i.v. ET-1 are inhibited by J-104132 after i.v. (0.1 mg/kg) or p.o. (1 mg/kg) administration. In anesthetized dogs, ET-1 was administered directly into the renal artery or brachial artery to generate dose-response (blood flow) curves, and the inhibitory potency of J-104132 (i.v. infusion) was quantified. J-104132 produced greater than 10-fold shifts in the ET-1 dose-response curves at 0.03 mg/kg/h (renal) and 0.3 mg/kg/h (brachial). Oral bioavailability of J-104132 in rats was approximately 40%. These studies indicate that J-104132 is a selective, potent, orally active antagonist of both ETA and ETB receptors and is an excellent pharmacological tool to explore the therapeutic use of a mixed ETA/ETB receptor antagonist.
99mTc-MIBI scintimammography was performed in a 24-year-old female with breast abscess. Intense tracer uptake in the breast abscess was noted on both early and delayed images. There are few descriptions of 99mTc-MIBI uptake in breast abscess, and this case indicated that abscess should be added to the differential diagnosis of breast 99mTc-MIBI uptake.