Biomedical subjects

Y Masuda

Publications and source records attributed to Y Masuda.

At least 307 records · Page 17Linked to original sources

PubMed1996

Platelet-derived growth factor B-chain homodimer suppressing a convulsion of epilepsy model mouse El.

El mouse is a mutant which has epileptic convulsions after tossing-up stimulations and has a hippocampal dysfunction. Platelet-derived growth factor B-chain homodimer has been reported to be a trophic factor of hippocampal neurons. We found that a recombinant PDGF-BB suppressed the convulsions of El mice in a dose-dependent manner. Furthermore, thrombin-treated mice manifested no convulsions, but thrombin receptor activating peptide-treated ones had convulsions. These findings suggest that an abnormality in PDGF-BB release may make El mice susceptible to tonic-clonic convulsions.

Animals↗

PubMed1996

Opioid peptide participates in post-tetanic twitch inhibition in guinea pig isolated ileum.

The effects of a mixture of peptidase inhibitors, consisting of 100 nM each of amastatin, phosphoramidon, and captopril, on the twitch inhibitory response (0.1 Hz, 0.5 ms duration, maximum intensity) exerted by opioid peptides were investigated. The opioid peptides, Met-enkephalin (50-200 nM), dynorphin(1-13) (0.2-1 nM), and beta h-endorphin (20-100 nM) concentration-dependently inhibited the electrically evoked twitch response. In the presence of the mixture of peptidase inhibitors, the twitch inhibition evoked by Met-enkephalin was significantly increased; however, the twitch inhibition evoked by beta h-endorphin and dynorphin(1-13) was only slightly increased. These increases were abolished by naloxone (NLX; 100 nM). Inhibition of the twitch response (0.1 Hz, 0.5 ms duration, maximum intensity) induced after high frequency stimulation (10 Hz, 0.5 ms pulse width, maximum voltage for various lengths of time) (post-tetanic twitch inhibition) was investigated in isolated guinea pig ileal longitudinal muscles. The mixture of peptidase inhibitors, which did not affect the twitch response or ACh-contraction, increased post-tetanic twitch inhibition. This increase was abolished by naloxone (100 nM). These results suggested that the potentiated post-tetanic twitch inhibition evoked by the peptidase inhibitors in the ileum was due primarily to mu-ligand(s) rather than to the kappa-type of endogenous opioid ligand(s) released from opioidergic neurons.

Acetylcholine↗

PubMed1996

A new technique for quantitative imaging of cerebrovascular reserve capacity using a double injection method with N-isopropyl-p-[123I]iodoamphetamine.

Estimation of local cerebrovascular reserve capacity is an important aspect of the management of patients with cerebrovascular occlusive disease. Regional normal values of cerebrovascular reserve capacity have not yet been established. Recently, Mori et al. (1994) introduced a method to quantitatively measure cerebral blood flow twice in 30 min after a double injection of N-isopropyl-p-[123I]iodoamphetamine using a background subtraction method. We utilized this double injection method in tandem with acetazolamide (20 mg/kg, intravenous injection) in 10 normal volunteers to produce a map of quantitative cerebrovascular reserve capacity using single photon emission computed tomography. The normal regional cerebrovascular reserve capacity was: frontal lobe, 51.0 +/- 19.8%; temporal lobe, 53.6 +/- 12.4%; parietal lobe, 69.3 +/- 31.8%; basal ganglia, 85.1 +/- 42.7%; cerebellum, 49.6 +/- 17.9% (mean +/- SD). One-way analysis of variance showed that the cerebrovascular reserve capacity did not differ significantly among structures. This new imaging technique and normal values of regional cerebrovascular reserve capacity may provide information about the pathophysiology and surgical indication in patient with occlusive cerebrovascular disease.

Adult↗

PubMed1996

Immunohistochemical localization of manganese superoxide dismutase in the rat cochlea.

There has been recent increasing interest in the involvement of superoxide radicals (O2-) and their scavenging enzymes, the superoxide dismutases, in the patho-physiology of certain diseases. Since mitochondria are significant intracellular sources of O2- and important targets of oxidant injury, determining the intracochlear localization of mitochondrial O2- scavenging enzyme may provide important insight into the pathogenesis of injury due to cochlear oxidants. In order to locate the mitochondrial O2- scavenging enzyme, manganese superoxide dismutase (MnSOD), the authors used a modified immunoglobulin peroxidase bridge sequence method to detect MnSOD in paraffin-embedded, formalin-fixed rat cochleas. Site-specific immunolocalization of MnSOD could be demonstrated in the cochlear labyrinth, suggesting that the generation of intracochlear O2- was possibly implicated in the metabolically active sites and sites rich in vascularity. This study also provided a useful probe for detecting MnSOD immunohistochemically from ethylenediamine tetra-acetic acid-treated materials without requiring an antigen retrieval procedure.

Animals↗

PubMed1996

Suppression of gravitropic response of primary roots by submergence.

Primary roots of six plant species were placed horizontally either in humid air or under water, and their growth and gravitropic responses were examined. In air, all the roots showed a normal gravitropic curvature. Under water without aeration, roots of rice (Oryza sativa L.), oat (Avena sativa L.), azuki bean (Vigna angularis Ohwi et Ohashi), and cress (Lepidium sativum L.) curved downward at almost same rate as in air, whereas the curvature of roots of maize (Zea mays L.) and pea (Pisum sativum L.) was strongly suppressed. Submergence did not cause a decrease in growth rate of these roots. When roots of maize and pea were placed horizontally under water without aeration and then rotated in three dimensions on a clinostat in air, they showed a significant curvature, suggesting that the step suppressed by submergence is not graviperception but the subsequent signal transmission or differential growth process. Constant bubbling of air through the water partly restored the gravitropic curvature of maize roots and completely restored that of pea roots. The curvature of pea roots was also partly restored by the addition of an inhibitor of ethylene biosynthesis, aminooxyacetic acid. In air, ethylene suppressed the gravitropic curvature of roots of maize and pea. Furthermore, the level of ethylene in the intercellular space of the roots was increased by submergence. These results suggest that the accumulation of ethylene in the tissue is at least partly involved in suppression of transmission of the gravity signal or of differential growth in maize and pea roots under conditions of submergence.

Aminooxyacetic Acid↗

PubMed1996

Effects of dietary phosphatidylcholine on memory in memory deficient mice with low brain acetylcholine concentration.

Data concerning the effect of phosphatidylcholine (PCh) administration on the improvement of memory in senile dementia of Alzheimer type are inconsistent, probably due to the different conditions under which studies were conducted. Animal studies provide a good model, but data on this is limited. We studied the effect of PCh on memory in memory deficient mice (Dull mice) with low brain acetylcholine (ACh) concentration and normal mice. Mice were fed 24% casein diet (control) or this diet supplemented with 2 or 8% egg yolk PCh from gestation (Experiment 1) and after weaning (Experiment 2). Memory acquisition and retention were studied by step-down type passive avoidance performance at 8 and 10 weeks old, respectively. Control group of Dull mice had poorer memories than that of the normal mice in Experiments 1 and 2. On the 2% PCh diet, Dull mice improved memory acquisition and retention in Experiment 1 and retention in Experiment 2. On the 8% PCh diet in Dull mice there was improvement of memory and retention in Experiment 1, but no effect was observed in Experiment 2 (P > 0.05). In the normal mice, the 2% PCh diet did not affect memory acquisition and retention, however on the 8% PCh diet, there was no or adverse effect. These results suggest that dietary supplementation of egg yolk PCh improves memory of Dull mice, particularly when given from gestation and that the 2% PCh diet elicits better response than the 8% PCh diet.

Acetylcholine↗

PubMed1996

Approach to risk assessment of chlorinated dioxins from Yusho PCB poisoning.

A Japanese was estimated to ingest 3 and 11 pg/kg/day of TEQ from PCDD/PCDFs and coplanar PCBs respectively through foods. A Japanese baby was calculated to consume 100-530 pg/kg/day level of TEQ through breast milk feeding, more than 60% being attributed to TEQ of coplanar PCBs. These intakes of TEQ were compared to the average (154 ng/kg/day) and minimum (28 ng/kg/day) intakes of Yusho, a PCB posioning occurred in Japan in 1968. There are three or four orders of magnitude difference between the daily TEQ intakes of general population and Yusho patients. However, the TEQ intakes by breast milk-fed babies of general population are at least 53 times less than the minimum intake of Yusho patients.

Benzofurans↗

PubMed1996

Bilateral congenital cholesteatoma.

We report a case of bilateral congenital cholesteatoma in a 6-year-old boy. Cholesteatoma was present in both ears around the tympanic isthmus (the only open passage from the tympanic cavity to the attic), extending to behind the horizontal portion of the facial nerve. This patient underwent a total of three canal wall up operations on each side to remove the cholesteatoma completely and improve hearing. This case fulfills the criteria proposed by Derlacki and Clemis in 1965. Bilateral congenital cholesteatoma is a rare condition, but the incidence of congenital cholesteatoma in children has increased recently for the following reasons: Reassessment of the criteria, the introduction of computed tomography, and increased awareness of congenital cholesteatoma. When operating on patients with bilateral cholesteatoma, the best method for preservation of hearing should be chosen. We discuss these problems in the present report.

Cartilage↗

PubMed1996

A computer-assisted operation for congenital aural malformations.

Surgical procedures to correct malformations of the external auditory canal are associated with the risk of facial nerve injury. We operated on a 6-year-old boy with a stenotic external auditory canal using a Viewing Wand (ISG Technologies Inc., Mississauga, Ontario, Canada) for improved visualization. We present our experience using this imaging system for aural surgery.

Child↗

PubMed1996

Possible use of a 3-D clinostat to analyze plant growth processes under microgravity conditions.

A three-dimensional (3-D) clinostat equipped with two rotation axes placed at right angles was constructed, and various growth processes of higher plants grown on this clinostat were compared with ground controls, with plants grown on the conventional horizontal clinostat, and with those under real microgravity in space. On the 3-D clinostat, cress roots developed a normal root cap and the statocytes showed the typical polar organization except a random distribution of statoliths. The structural features of clinostatted statocytes were fundamentally similar to those observed under real microgravity. The graviresponse of cress roots grown on the 3-D clinostat was the same as the control roots. On the 3-D clinostat, shoots and roots exhibited a spontaneous curvature as well as an altered growth direction. Such an automorphogenesis was sometimes exaggerated when plants were subjected to the horizontal rotation, whereas the curvature was suppressed on the vertical rotation. These discrepancies in curvature between the 3-D clinostat and the conventional ones appear to be brought about by the centrifugal force produced. Thus, the 3-D clinostat was proven as a useful device to simulate microgravity.

Cell Wall↗

PubMed1996

Effects of short-term (2 weeks) streptozotocin-induced diabetes on acetylcholine and noradrenaline in the salivary glands and secretory responses to cholinergic and adrenergic sialogogues in mice.

Acetylcholine and noradrenaline concentrations in the submandibular, parotid and sublingual glands, and pilocarpine-, isoproterenol- and phenylephrine-induced salivation, were estimated in streptozotocin (STZ)-induced diabetic mice. Diabetic mice showed significant increases in acetylcholine and noradrenaline (expressed as nmol/gland) in sublingual and submandibular glands, respectively. The total volume of crude whole saliva in diabetic mice in response to pilocarpine and isoproterenol but not to phenylephrine was significantly reduced. These results suggest that alterations in the neurotransmitter levels and secretory function in the salivary glands occur rapidly after the induction of STZ diabetes, and that the secretory function appears to be more susceptible to effects of diabetes in the early stages than the autonomic nervous system. Since the alterations in neurotransmitter concentrations in diabetic salivary glands were slight and partial, it seems that they are unrelated to the markedly reduced salivation in response to pilocarpine and isoproterenol observed in these short-term diabetic mice.

Acetylcholine↗

PubMed1996

Middle ear anomalies induced by hypertriazene administration in the mouse.

The middle ear is derived from various embryonic tissues. Many experiments using teratogens have been performed, employing the difference of each tissue's sensitivity to the teratogen and the tissue's critical time of development. Triazene, a foliate metabolism antagonist, produced anomalies in fetuses that resembled those associated with thalidomide in humans, the so-called the first and second branchial syndrome. In our experiment, we administrated 3,3-dimethyl-1-phenyltriazene, an inductor of triazene, to pregnant mice at 7 to 14 days of gestation resulting in unique fetal anomalies. We examined the development of the stapes, stapedial artery, facial nerve, and oval window using an optical microscopic and three-dimensional reconstruction. Middle ear and facial nerve anomalies in mice depend on the gestation day when triazene is administrated. The stapedial artery, oval window, facial nerve (horizontal segment), stapes footplate, and styloid process are affected on the 9th to 11th administration day, the annular stapedialis on the 10th to 11th day, and the malleus and incus on the 9th to 11th day. The use of the Vox View/Mac, allowed us to create three-dimensional pictures from two-dimensional slides providing an improved understanding of the relationships between anatomical structures.

Animals↗

PubMed1996

Large-cell variants of mantle cell lymphoma: cytologic characteristics and p53 anomalies may predict poor outcome.

Large-cell variants are uncommon in mantle cell lymphoma (MCL). Here we describe the pathologic and clinical findings in five patients with large-cell lymphoma related to MCL (L-MCL), and compare them to a group of classic small-cell MCL (s-MCL) cases. Histologically, the MC origin of the large cells was evinced by their association with a small mantle cell component in the same tissue, or their distribution in a classic mantle zone pattern, or their development in a patient with previous s-MCL. The large cells were either pleomorphic mantle cells (case 1) or transformed blast-like cells (case 2-5). The median nuclear diameter, median nuclear area and proliferation index of L-MCLs and s-MCLs, were statistically different. Immunophenotypic characterization of four specimens of L-MCL and 10 of s-MCLs with a large panel of antibodies showed the classic findings of MCL, i.e. the IgM+ D+/-, CD5+, CD10-, CD23- phenotype in all cases except two (one CD5- and one CD23+), and the association with a loose follicular dendritic cell network. Two of four L-MCLs and 5/10 s-MCLs demonstrated rearrangements of the bcl-1 gene by Southern blot or by polymerase chain reaction (PCR); 2/4 L-MCLs and 1/9 s-MCLs had p53 mutations on single-strand conformation polymorphism analysis; none of the 14 specimens showed rearrangement of bcl-2 by PCR or bcl-6 and c-myc by Southern blot. All patients with 'transformed' histology (versus 37% of all others) died of lymphoma; their survival (15-18 months; median 17) was much shorter than that of all the others (28-117+ months; median 43) (P=0.0035). All three patients with p53 anomalies, two of whom had tumours with transformed histology, died of their disease in a short time (15, 18 and 28 months). In contrast, the presence of bcl-1 rearrangements did not have prognostic implications. This study documents the existence of large-cell variants of MCL and the poor prognosis associated with the 'transformed' cytologic type and/or p53 abnormalities.

Aged↗

PubMed1996

Effects of hypergravity on growth and cell wall properties of cress hypocotyls.

Elongation growth of etiolated hypocotyls of cress (Lepidium sativum L.) was suppressed when they were exposed to basipetal hypergravity at 35 x g and above. Acceleration at 135 x g caused a decrease in the mechanical extensibility and an increase in the minimum stress-relaxation time of the cell wall. Such changes in the mechanical properties of the cell wall were prominent in the lower regions of hypocotyls. The amounts of cell wall polysaccharides per unit length of hypocotyls increased under the hypergravity condition and, in particular, the increase in the amount of cellulose in the lower regions was conspicuous. Hypergravity did not influence the neutral sugar composition of either the pectin or the hemicellulose fraction. The amount of lignin was also increased by hypergravity treatment, although the level was low. The data suggest that hypergravity modifies the metabolism of cell wall components and thus makes the cell wall thick and rigid, thereby inhibiting elongation growth of cress hypocotyls. These changes may contribute to the plants' ability to sustain their structures against hypergravity.

Acceleration↗

PubMed1996

Purification and characterization of bleomycin hydrolase, which represents a new family of cysteine proteases, from rat skin.

Bleomycin (BLM) hydrolase, which hydrolyzes the carboxyamide bond in the beta-amino-alanine moiety, was purified from newborn rat skin. The enzyme was purified 2,500-fold over the crude extract to apparent homogeneity in five steps in the presence of 2-mercaptoethanol: 45-55% ammonium sulfate fractionation, followed by chromatographies on Sephacryl S-200, DEAE-cellulofine, Phe-Superose, and Mono Q ion-exchange. The native enzyme had a molecular mass of 280 kDa according to gel filtration. The subunit molecular mass was estimated as 48 kDa by SDS-PAGE, indicating that the enzyme was comprised of six identical subunits. The amino acid sequence of its NH2-terminus was determined to be acetyl-Met-Asn-Asn-Ala-Gly-Leu-Asn-Ser-Glu-Lys-, which was not found in the amino acid sequence database. The optimum pH of the enzyme was 7.5 with pepleomycin (PLM). The Km and Vmax values were 2.1 mM and 6.8 mu mol center dot mg-1 center dot h-1 for PLM, and 1.8 mM and 7.2 mu mol center dot mg-1 center dot h-1 for BLM-A2, respectively. The enzyme activity was inhibited by iodoacetic acid, N-ethylmaleinimide (NEM), and p-chloromercuribenzoic acid (pCMB) as well as divalent cations such as Cu2+, Cd2+, Hg2+, and Zn2+. It was effectively inhibited by a cysteine protease inhibitor E-64. However, cystatins A and C did not inhibit the activity. BLM hydrolase exhibited broad aminopeptidase substrate specificity towards aminoacyl-beta-naphthylamides such as basic, neutral, and hydrophobic amino acid residues, as well as acidic residues. These results indicated that BLM hydrolase represents a new family of cysteine proteases. Western blotting and immunohistochemical analyses showed that BLM hydrolase is ubiquitous in various rat tissues but at low levels in lung and adult skin tissues, suggesting that this enzyme plays an important role in the metabolism of antibiotics.

Amino Acid Sequence↗

PubMed1996

Cloning and analysis of cDNA encoding rat bleomycin hydrolase, a DNA-binding cysteine protease.

We isolated and characterized almost the entire cDNA encoding BLM hydrolase from rat spleen cDNA libraries. The cDNA encoded a polypeptide composed of 454 amino acids, that had a slightly larger molecular mass than that was previously estimated by SDS-PAGE for purified BLM hydrolase subunit. Amino acid sequence alignments showed that rat BLM hydrolase is homologous to that of rabbit (94% identity of partial amino acid sequence), yeast cysteine protease (39% identity), and the pepC gene products of three bacteria (34-40% identity). In addition, it contained the three regions that are conserved in other cysteine proteases and thought to constitute the catalytic center. These results indicated that rat BLM hydrolase is a member of the papain superfamily of cysteine proteases. Sequencing revealed several putative sites phosphorylated by different types of protein kinases, but no signal sequence, transmembrane domain, N-linked glycosylation site or DNA-binding motif. The yeast homolog is a DNA-binding cysteine protease [Xu et al. (1994) J. Biol. Chem, 269, 21177-21183]. We demonstrated that rat BLM hydrolase also binds the single-stranded form of the Ga14 DNA-binding site oligonucleotide with high affinity compared with that of the double-stranded form. Northern blots revealed that the level of BLM hydrolase mRNA expression was very low in the rat skin, lung, and skeletal muscle. Furthermore, BLM hydrolase mRNA was ubiquitously expressed in the human cell lines, HeLa, SKG-IIIa, FL, KB, HEp-2, U373 GM, P3HR-1, Raji, THP-1, Jurkat, and Molt-4. These results suggested that BLM hydrolase plays important physiological roles, including the metabolism of antibiotics.

Amino Acid Sequence↗

PubMed1996

Complete nucleotide sequences of the genes encoding translation elongation factors 1 alpha and 2 from a microsporidian parasite, Glugea plecoglossi: implications for the deepest branching of eukaryotes.

Complete nucleotide sequences of the genes putatively encoding translation elongation factors 1 alpha (EF-1 alpha) and 2 (EF-2) from a mitochondrion-lacking protozoan, Glugea plecoglossi, that belongs to microsporidians were determined. The deduced amino acid sequences of the putative EF-1 alpha and EF-2 of Gl. plecoglossi showed very unusual features compared with typical eukaryotic sequences. The degree of divergence was especially great in the EF-1 alpha sequence, although it clearly showed a eukaryotic feature when aligned with homologs from the three primary kingdoms. Phylogenetic analyses of EF-1 alpha and EF-2 on the basis of the maximum likelihood method of protein phylogeny clearly and consistently suggested that among eukaryotic species being analyzed, Gl. plecoglossi and another mitochondrion-lacking protozoan, Giardia lamblia, respectively represent the earliest and the second earliest offshoots of eukaryotes. When the EF-1 alpha and EF-2 phylogenies were totally evaluated, the earliest divergence of Gl. plecoglossi in eukaryotes became more clearly confirmed. If the phylogenetic relationship inferred from the present analysis are correct, microsporidians might be extremely ancient eukaryotes that diverged before the occurrence of mitochondrial symbiosis.

Animals↗

PubMed1996

Presence of human papillomavirus type 6f in tonsillar condyloma acuminatum and clinically normal tonsillar mucosa.

An attempt was made to detect human papillomavirus (HPV) in 8 cases of oral papilloma by Southern blot hybridization. HPV type 6 was identified in a case of tonsillar condyloma acuminatum, but neither HPV type 6 nor 11 was found in the 7 other cases of squamous papilloma. The hybridization pattern of the HPV type 6 DNA after digestion with restriction enzymes revealed that the HPV was of the 6f subtype. DNA samples isolated from the condyloma acuminatum, 3 peripheral specimens of clinically normal tonsillar mucosa, a swab sample and saliva from the male patient with this tonsillar condyloma acuminatum were examined further by polymerase chain reaction (PCR). HPV type 6 DNA was detected in the tonsillar condyloma acuminatum and the 3 specimens of clinically normal tonsillar mucosa, but no HPV type 6 DNA was detectable in the normal tonsillar mucosa by Southern blot hybridization using a whole HPV DNA probe. The presence of a small amount of HPV in clinically normal tissue detectable only by PCR suggests latent infection of peripheral tissues with HPV produced from the condyloma acuminatum. Although HPV type 6 DNA was not detectable in the swab and saliva samples of this single case, further study is necessary for the clinical application of preoperative virological diagnosis by PCR using these samples.

Adult↗