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Biomedical subjects

M Masutani

Publications and source records attributed to M Masutani.

At least 55 records · Page 3Linked to original sources

Messenger RNA for the guanine nucleotide-binding regulatory protein (G protein) is reduced in the acute ischemic myocardium.

It has been reported that the function of the guanine-binding regulatory protein (G protein), especially the alpha subunit of the stimulatory G protein (Gs alpha), in myocardium is decreased with acute ischemia. However, it is unclear whether this decrease is due to transcriptional or post-transcriptional changes. Moreover, no studies have examined the distribution of G protein mRNA in ischemic myocardium using in situ hybridization. The purpose of this study was to explore alterations in mRNA of G proteins (Gs and Gi) in ischemic hearts using in situ hybridization. We measured the levels of mRNA for Gs alpha and Gi alpha in ischemic and non-ischemic myocardium by in situ hybridization using a radioisotope imaging system. We compare these mRNA levels in ischemic and non-ischemic myocardium with Northern blot analysis and the protein levels of G proteins by Western blot analysis. The mRNA for Gs alpha and Gi alpha was distributed diffusely in normal hearts. Levels of mRNA detected by in situ hybridization were substantially reduced by acute ischemia, and these results were confirmed by Northern and Western blot analysis. These results suggest that decreased levels of mRNA and protein for G proteins may underlie the impaired function of the receptor--G protein--adenylate cyclase system in ischemic myocardium. In addition, quantitative evaluation of mRNA is possible by in situ hybridization and correlates well with Northern analysis.

Acute Disease↗

Role of poly(ADP-ribose) polymerase in cell-cycle checkpoint mechanisms following gamma-irradiation.

A nuclear poly(ADP-ribose) polymerase (PARP) is activated by gamma-irradiation and consequently synthesizes poly(ADP-ribose) by binding to DNA strand-breaks. This property suggests that PARP is a DNA strand-break-signal generator. Meanwhile, the cell-cycle arrest occurs in G1 and G2 phases following gamma-irradiation. We found that PARP inhibitors including 3-aminobenzamide (3-AB) suppressed G1 arrest and enhanced G2 arrest following gamma-irradiation. These observations suggested that PARP is critical for the induction of G1 arrest and is also involved in the regulation of G2 arrest. Furthermore, the effects of 3-AB on the G1-arrest signal-transduction pathway were also studied. We found that p53 stabilization following gamma-irradiation was not inhibited but the p53-responsive transient increases of WAF1/CIP1/p21 and MDM-2 mRNA were suppressed by 3-AB. Therefore, it is suggested that PARP participates in G1-arrest signal-transduction pathway through the modulation of WAF1/CIP1/p21 and MDM-2 mRNA expression.

Animals↗

Cloning and functional expression of poly(ADP-ribose) polymerase cDNA from Sarcophaga peregrina.

A cDNA spanning the entire coding region for poly(ADP-ribose) polymerase (PARP) of Sarcophaga peregrina was isolated and the nucleotide sequence was determined. The longest open reading frame encodes a polypeptide of 996 amino acid residues with a molecular mass of 113,033 Da. The similarities to the human PARP in amino acid sequence were relatively low in the DNA-binding and auto-modification domains, but very high in the C-terminal catalytic domain: identity of amino acids is 34% in the N-terminal DNA-binding domain (residues 1-369), 27% in the auto-modification domain (residues 370-507), and 56% in the C-terminal NAD-binding domain (residues 508-996). Two zinc-fingers (C-X2-C-X28-H-X2-C and C-X2-C-X31-H-X2-C)2 and a basic region in the N-terminal DNA-binding domain recognized in other PARP are conserved. Downstream of the basic region, another cysteine-rich motif (C-X2-C-X13-C-X9-C), a putative zinc-finger, was found to be well conserved in the PARP of Sarcophaga, Drosophila and human. A leucine-zipper motif (L-X6-L-X6-L-X6-L) which was found in the auto-modification domain of Drosophila PARP, is disrupted in the Sarcophaga enzyme: the second leucine is replaced by proline, and the third leucine by valine. Full-length cDNA for Sarcophaga PARP was cloned into an expression plasmid and expressed in Escherichia coli. A lysate of E. coli cells containing expressed protein reacted with antibody against Sarcophaga PARP, and PARP activity was detected. Thus, we conclude that isolated cDNA encodes a functional Sarcophaga PARP cDNA.

Amino Acid Sequence↗

Non-covalent interaction between poly(ADP-ribose) and cellular proteins: an application of a poly(ADP-ribose)-western blotting method to detect poly(ADP-ribose) binding on protein-blotted filter.

We describe a sensitive method for the detection of interactions between poly(ADP-ribose) and proteins. Proteins were blotted onto nitrocellulose filters and incubated with 32P-labeled poly(ADP-ribose). Purified core histones and poly(ADP-ribose) polymerase were found to bind poly(ADP-ribose) polymer. Blots of HeLa cell protein extracts revealed a 48 kDa protein and several others of smaller than 35 kDa likewise bound the polymers even at high salt concentrations. Those proteins, along with a 69 kDa protein, also showed resistance to competitor DNA. Polymer binding of aforesaid HeLa extract proteins was restricted to polymers above 20 residues in length. Thus poly(ADP-ribose)-protein affinities were polymer-length dependent.

Base Sequence↗

Localization of protein kinase C alpha, beta and gamma subspecies in sensory axon terminals of the rat muscle spindle.

The localization of protein kinase C (PKC) alpha, beta and gamma subspecies in sensory axon terminals of muscle spindles in the plantar lumbrical muscles of rat was investigated by light and electron microscopic immunocytochemistry using monoclonal and polyclonal antibodies. Immunoreactivity for these subspecies was detected specifically in sensory axon terminals which wound spirally around the intrafusal muscle fibres of the muscle spindle. Immunostaining was found to be stronger with polyclonal than with monoclonal antibodies. By electron microscopy, immunoreactivity for alpha, beta and gamma subspecies was almost diffusely distributed in the cytoplasm of the axon terminal, and the overall pattern of distribution of immunoreactivity was similar for all three subspecies. In the cases of alpha and beta subspecies, some intensely immunostained regions were found in the cytoplasm, but no definite subcellular structures corresponding to such regions could be identified. Considering that PKC plays a crucial role in the regulation of ion channels, it is suggested that PKC might be involved in the control of mechanoelectric transduction in sensory axon terminals.

Animals↗

Suppression of G1 arrest and enhancement of G2 arrest by inhibitors of poly(ADP-ribose) polymerase: possible involvement of poly(ADP-ribosyl)ation in cell cycle arrest following gamma-irradiation.

Low-dose gamma-irradiation of mouse embryonic fibroblast C3D2F1 3T3-a cells caused G1 arrest along with G2 arrest and inhibition of replicative DNA synthesis. When the cells were cultured in the presence of inhibitors of poly(ADP-ribose) polymerase [EC 2.4.2.30], such as 3-aminobenzamide, benzamide and luminol, G1 arrest of C3D2F1 3T3-a cells was suppressed and enhancement of G2 arrest was observed. In contrast, 3-aminobenzoic acid, a non-inhibitory analog of 3-aminobenzamide, did not suppress G1 arrest following gamma-irradiation. These results suggest that the poly(ADP-ribosyl)ation reaction is critical for the pathway of G1 arrest and is also involved in the pathway of G2 arrest.

Animals↗

Synaptophysin immunocytochemistry in the regenerating sprouts from the nodes of Ranvier in injured rat sciatic nerve.

Following crush injury of rat sciatic nerve, strong synaptophysin immunoreactivity was demonstrated in the regenerating sprouts that emerged from the proximal nodes of Ranvier and in their growth cones that extended through the space between Schwann cell basal lamina and myelin sheath of the parent axon. These findings suggest that synaptophysin is involved in the growth regulation of regenerating sprouts.

Animals↗

Molecular cloning of the cDNAs for the four subunits of mouse DNA polymerase alpha-primase complex and their gene expression during cell proliferation and the cell cycle.

The DNA polymerase alpha-primase complex purified from mouse FM3A cells is composed of four polypeptides with molecular masses of 180, 68, 54, and 46 kDa. The largest subunit has DNA polymerase activity, the two smallest subunits have DNA primase activity, and the function of the 68-kDa subunit is unknown. We have isolated the cDNAs of the four subunits by low stringency hybridization and reverse transcription polymerase chain reaction and determined their nucleotide sequences. The predicted amino acid sequence of the 180-kDa subunit shows 88, 38, 34, and 32% identity to those of the catalytic subunits of human, Drosophila melanogaster, Schizosaccharomyces pombe, and Saccharomyces cerevisiae DNA polymerase alpha, respectively, and contains seven regions whose orders and sequences are highly conserved among viral and other eukaryotic DNA polymerases. The deduced amino acid sequence of the 68-kDa subunit shows 25% identity to that of the 73-kDa subunit of D. melanogaster DNA polymerase alpha-primase, shows no significant sequence similarity to any other protein in the data bases, but contains a potential phosphorylation site(s) for cdc2 kinase. The amino acid sequence of the 54-kDa subunit shows 32% identity to that of the large subunit of S. cerevisiae DNA primase. During activation of quiescent Swiss mouse 3T3 cells to proliferate, the levels of mRNA of the four subunits of the DNA polymerase alpha-primase complex increased before DNA synthesis. In growing mouse FM3A cells, the transcripts of the four subunits are present throughout the cell cycle and increase slightly prior to the S phase.

Amino Acid Sequence↗

Ultrastructural localization of protein kinase C beta-subspecies in the axon terminal of rat neuromuscular junction.

Ultrastructural localization of protein kinase C (PKC) beta-subspecies in neuromuscular junctions of the rat lumbrical muscle was investigated by the immunoperoxidase and immunofluorescence methods. By light microscopy, PKC beta-like immunoreactivity (PKC beta-LIR) was found in the axon terminal expansions as well as in the preterminal axons. By confocal laser scanning microscopy, the staining for PKC beta-like immunoreactivity was more intense in the presynaptic regions just in contact with the acetylcholine receptor stained by FITC-alpha-bungarotoxin. By electron microscopy, PKC beta-like immunoreactivity was distributed non-uniformly in the terminal expansions. In the terminal expansions, PKC beta-like immunoreactivity was accumulated in the presynaptic regions in contact with the post-synaptic folds. This accumulation was approximately 0.1-0.2 microns in diameter, which comprised a part of the presynaptic plasma membrane and a group of synaptic vesicles adjacent to it. Weak immunoreactivity was also found diffusely in the axoplasmic matrix. The discrete presynaptic accumulation of PKC beta-subspecies may represent the strategical localization specialized for the effective regulation of neurotransmitter release.

Animals↗

Contact sensitivity and cross-reactivity of budesonide.

5 cases of allergic contact dermatitis due to budesonide are described. We studied the antigen determinant structures in these cases by applying patch tests with several substances related to budesonide. 2 cases showed cross-reactions to both amcinonide and prednisolone acetate. The antigen determinant structure is also discussed.

Adult↗

[Effect of surfactant on mouse alveolar macrophage cytotoxicity].

Surfactant has been shown to have several immunologic activities in addition to its property of lowering tension. To investigate the effect of surfactant on alveolar macrophage cytotoxicity against tumor cells, we compared the cytolytic activity, tumor necrosis factor (TNF) activity and L-arginine-dependent NO2- production of mouse alveolar macrophages in the presence of surfactant with those of alveolar macrophages alone. Furthermore, we measured the concentrations of inositol-1,4,5, triphosphate (IP3) and diacylglycerol (DG) both of which are second messengers of intracellular signals. Cytolysis, TNF activity and NO2- production were enhanced by lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). This enhancement was further increased by addition of surfactant. The surfactant did not enhance the concentration of IP3, but enhanced that of DG in alveolar macrophages activated by LPS or IFN-gamma. These data suggest that surfactant upregulated the enhancement of alveolar macrophage cytotoxicity by LPS and IFN-gamma, and this effect was related to an increase in the concentration of DG in activated alveolar macrophages.

Animals↗

[A case of piperacillin-induced pneumonitis].

A 43-year-old woman was treated with piperacillin (PIPC) for spiking fever. Although she was afebrile, fever recurred on the 18th day of PIPC administration with progressive dyspnea and diffuse ground glass shadows on the chest X-ray. Bronchoalveolar lavage fluid (BALF) showed marked increase of total cell number and percentage of lymphocytes and a reduction of the ratio of CD4/CD8. Transbronchial lung biopsy (TBLB) specimen revealed interstitial infiltration of lymphocytes and histiocytes with granulomatous lesions. The drug lymphocyte stimulation test (DLST) was positive for PIPC. Based on these findings, the diagnosis of PIPC-induced pneumonitis was made. Recently, the incidence of drug-induced pneumonitis has increased, but to our knowledge this is a rare case report of PIPC-induced pneumonitis.

Adult↗

Localization of smg p25A/rab3A p25, a small GTP-binding protein, at the active zone of the rat neuromuscular junction.

smg p25A is a small G protein which has been suggested to regulate neurotransmitter release from the synapses. We investigated here the ultrastructural localization of this small G protein in the rat neuromuscular junction by an immunoperoxidase method. The results showed that smg p25A was distributed non-uniformly on the presynaptic plasma membrane and among the synaptic vesicles with the focal accumulation on the discrete presynaptic sites which corresponded to the active zones, the regions of the presynaptic plasma membrane specialized for the exocytosis of the synaptic vesicles. This unique distribution of smg p25A suggests that it plays an important role in the attachment and fusion of the synaptic vesicles with the active zones.

Animals↗

Protein kinase C (alpha, beta, gamma) in Pacinian corpuscle.

Immunocytochemical demonstration of protein kinase C (PKC) subspecies (alpha, beta, gamma) was carried out in Pacinian corpuscles of rat hind feet using monoclonal or polyclonal antibodies against each of these subspecies. The inner core cells and lamellae and the Schwann cell cytoplasm of the nerve fiber innervating the corpuscle were strongly positive for PKC alpha-immunoreactivity (IR). In contrast, the axon terminal and the outer core did not display any positive alpha-IR. Very weak PKC beta-IR was detected in the ultraterminal region of the axon terminal, while the trunk region showed no immunoreactivity. Very faint PKC beta-IR was found also in the lamellar cells located at the periphery of the inner core and the endoneurial fibroblasts in the intermediate layer. PKC gamma-IR was not detected in any part of the corpuscle. The strong PKC alpha-IR in the inner core and the presence or absence of PKC alpha-, beta-, and gamma-IR in the axon terminal are discussed from the point of view of the functional aspects of each part.

Animals↗

[Holter electrocardiographic findings in surgical patients during the perioperative period].

Eighty patients undergoing abdominal surgery were studied to evaluate ECG changes in perioperative period and also identify the factors influencing the incidence and the severity of postoperative ventricular arrhythmia. Holter ECG was recorded with CM5 and NASA leads from the night before operation to the night of the 2nd postoperative day. Tachycardia (greater than or equal to 100 beats.min-1) was found in 46.3% of the patients preoperatively and in 55% postoperatively. Bradycardia (less than or equal to 50 beats.min-1) was found in 30% of the patients mostly in the night prior to the operation, while only 1 patient (1.3%) demonstrated bradycardia postoperatively. SVPCs were observed in high incidence ranging from 75% preoperatively to 85% postoperatively. Two patients had paroxysmal supraventricular tachycardia postoperatively. VPCs were observed in 42.5% of the patients preoperatively and in 53.8% postoperatively. Warning arrhythmias which were ranked as more dangerous than Lown 2 were observed in 15% of the patients preoperatively, in 11.3% intraoperatively and in 23.8% postoperatively. Serious arrhythmias which needed immediate treatment were found in 6.3% of the patients preoperatively, in 10% intraoperatively and in 11.3% postoperatively. ST depression was recorded in 11 patients at CM5 and 2 patients at NASA leads. Chi-square and Hayashi's multidimensional quantification analyses were applied to determine the relationship between postoperative VPCs and pre- and intra-operative clinical factors. Factors such as age, type of surgery, intraoperative VPCs, ASA classification, ischemic changes in preoperative ECG, intraoperative blood loss, operation time, Goldman score, untreated hypertension as well as ischemic heart disease and abnormal findings of Master ECG were considered to be contributing to the high incidence and the severity of post-operative VPCs. When multidimensional quantification analysis is applied to the data, the occurrences of no VPCs, occasional VPCs, warning VPCs and serious VPCs could be predicted in postoperative patients.

Abdomen↗

Structure and expression during development of Drosophila melanogaster gene for DNA polymerase alpha.

The Drosophila melanogaster gene and cDNA which span the entire open reading frame for DNA polymerase alpha, were cloned, and their nucleotide sequences were determined. The gene consists of 6 exons separated by 5 short introns. The major transcription initiation site was localized 85 bp upstream from the initiation codon. The nucleotide sequence of the open reading frame revealed a polypeptide of 1,505 amino acid residues with a molecular weight of 170,796. The amino acid sequence of the polypeptide was 37% homologous with that of the catalytic subunit of human DNA polymerase alpha. This sequence contains six regions, the orders and amino acid sequences of which are highly conserved among a number of other viral and eukaryotic DNA polymerases. We found 7 amino acid residues in the region between the 639th and 758th positions, identical to those essential for the active site of Escherichia coli DNA polymerase I-associated 3'----5' exonuclease. Thus, the exonuclease activity may be associated with Drosophila DNA polymerase alpha. Levels of the DNA polymerase alpha mRNA were high in unfertilized eggs and early embryos, relatively high in adult female flies and second-instar larva, and low in bodies at other stages of development. This feature of the expression is similar to that of the proliferating cell nuclear antigen (an auxiliary protein of DNA polymerase delta) and seems to coincide with the proportions of proliferating cells in various developmental stages. As the half life of the mRNA for DNA polymerase alpha in cultured Drosophila Kc cells was 15 min, expression of the DNA polymerase alpha gene is probably strictly regulated at the step of transcription.

Amino Acid Sequence↗

A study of systemic and topical effects of topical steroid application through the comparison of two application schedules.

We compared two application schedules of a topical steroid, BV (Betamethasone valerate). The schedules were once daily and twice a week on juvenile Wistar rats treated for four weeks. Steroid actions were assessed topically (skin thickness and epidermal Langerhans cell density) and systemically (body weight and internal organ wet weights). The results revealed some rather severe systemic effects caused by frequent steroid application. And we also found a uniquely weak BV effect with Langerhans cells compared to obvious systemic effects on rats. We came to the conclusion that frequent steroid application to the young should be avoided.

Administration, Topical↗