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Biomedical subjects

M Kato

Publications and source records attributed to M Kato.

At least 19 recordsLinked to original sources
PubMed1992

Changes of DNA methylation in protooncogenes in the process of radiation-induced transformation of mouse m5S/1M cells in vitro.

To assess the importance of changes in DNA methylation in an X-ray-induced cellular transformation process, methylation patterns of five nuclear protooncogenes in fifteen transformant clones were studied and compared to that of the parental non-transformed cell line m5S/1M. All transformants examined revealed an alteration in DNA methylation in some of the genes, although these changes were variable among them. A comparison of cellular characteristics with corresponding DNA methylation changes in different clones suggested that the loss of contact inhibition and the gain of anchorage independency were associated with increases of methylation in many genes, whereas the acquisition of tumorigenicity was often accompanied by a decrease of methylation in the N-myc and c-myc genes. Resultant data indicate that the alteration of DNA methylation is closely related to transformation process, yet how this involvement occurs is complex and remains unclear.

Animals↗
PubMed1992

Purification and characterization of proteinase In, a trypsin-like proteinase, in Escherichia coli.

We previously found a trypsin-like proteinase which momentarily appears immediately before DNA synthesis in the cell cycle of Escherichia coli synchronized by phosphate starvation and which is closely related to the initiation of DNA replication (Kato, M., Irisawa, T., Morimoto, Y. and Muramatu, M., unpublished results). The proteinase was named proteinase In. It was purified approximately 2880-fold with a recovery of 15%. The isolated enzyme appeared homogeneous by gel filtration and electrophoresis. Its molecular mass was estimated by analytical gel filtration and SDS/PAGE as approximately 66 kDa. The isoelectric point of proteinase In is 4.9 and its optimal pH is approximately 9. Although protein In hydrolyzes fluorogenic substrate for trypsin, its hydrolytic activity seems markedly affected by amino-acid sequence lying towards the N-terminal from the P1 (lysine, arginine) residue. The proteinase does not hydrolyze N2-benzoyl-D,L-arginine-4-nitronanilide and fluorogenic substrates for chymotrypsin and elastase. The proteinase activity is inhibited by leupeptin, antipain and 4-nitrophenyl 4-guanidinobenzoate, but the effects of tosyl-L-lysine chloromethane, diisopropylfluorophosphate, benzamidine and pentamidine isethionate on the proteinase activity are weak or not inhibitory. Its activity is strongly affected in the presence of NaCl and KCl, and at a concentration of 1.5 M, these increase the activity 14-fold and 13-fold, respectively, above that without salt. Proteinase In was strongly inhibited by various esters of trans-4-guanidinomethylcyclohexanecarboxylic acid, and their inhibitory effects were roughly correlated with those on growth of E. coli. Proteinase activity was found in the cytoplasmic fraction.

Amino Acid Sequence↗
PubMed1992

Rolling mouse Nagoya as a mutant animal model of basal ganglia dysfunction: determination of absolute rates of local cerebral glucose utilization.

In order to elucidate the neuronal mechanism of the motor disturbances of the Rolling mouse Nagoya (rolling), a neurological mutant mouse (genotype rol/rol) showing frequent lurching and falling over on walking, we determined absolute rates of local cerebral glucose utilization (LCGU) with the [14C]deoxyglucose method. The rates were compared with those of heterozygote (+/rol) with normal behavior, and of normal mice (+/+) of the same strain (C3Hf/Nga). Rolling showed marked and significant increases in LCGU in the structures of the basal ganglia such as the globus pallidus, entopeduncular nucleus, substantia nigra pars compacta and pars reticulata, and subthalamic nucleus, confirming our previous finding with semiquantitative LCGU determination. Additional significant but much less marked increases in LCGU of rolling were found in some structures of the brainstem and limbic system, such as the pedunculopontine nucleus, red nucleus, ventral tegmental area, lateral habenula, and CA1 and CA3 of the hippocampus. Although rolling has been regarded as an animal model of cerebellar ataxia, rolling showed no alterations of LCGU in the cerebellum. The heterozygote showed intermediate increases in LCGU between rolling and normal mice in the basal ganglia structures such as the globus pallidus, substantia nigra pars reticulata and subthalamic nucleus. Our findings indicate that rolling has a definite, genetically determined dysfunction of the basal ganglia. The primary site of the basal ganglia dysfunction might probably be in the striatum, involving both the neostriatum and limbic striatum, and resulting in secondary dysfunction in their target structures.

Animals↗
PubMed1992

Walking of cats on a grid: performance of locomotor task in spinal intact and hemisected cats.

We have investigated interlimb coordination during walking by observing locomotion of cats on a grid. Control cats made no error in forelimb placement on the grid, and landed their hindlimbs on the rung where each ipsilateral forelimb left moments earlier. This suggests that locomotor command signals were modified by grid information including its size and direction and affected the pattern generators of both forelimbs and hindlimbs. Hemisected cats, made both at high cervical and lower thoracic, showed deteriorated placement of the hindlimbs suggesting that interlimb coordination is carried out mainly by descending pathways from the brainstem such as ventrolateral fasciculus and dorsolateral fasciculus. Interlimb reflex pathways may play a limited role.

Animals↗
PubMed1992

Autocrine and paracrine effects of endothelium-derived relaxing factor on intracellular Ca2+ of endothelial cells and vascular smooth muscle cells. Identification by two-dimensional image analysis in coculture.

To elucidate the effects of endothelium-derived relaxing factor (EDRF) released from vascular endothelial cells (ECs) on handling of intracellular calcium ion (Ca2+i) in ECs themselves and vascular smooth muscle cells (VSMCs), we measured the Ca2+i by two-dimensional digital image analysis of fura-2-loaded ECs and VSMCs in tissue culture. In isoculture of one cell type, adenosine triphosphate (ATP, 1 microM) transiently increased the Ca2+i of both ECs and VSMCs. High-K+ depolarization or angiotensin II also elevated the Ca2+i of VSMCs, whereas neither stimulants changed the Ca2+i of ECs. In coculture of ECs with VSMCs, the same dose of ATP rapidly increased the Ca2+i of ECs and then transiently decreased the Ca2+i of VSMCs to below the resting level. The maximal Ca2+i-modulating effects of ATP on both cell types were reproducible after the second application of ATP. Three kinds of EDRF blockers (L-NG-monomethylarginine, methemoglobin, or methylene blue) potentiated the ATP-induced Ca2+i rise in ECs and attenuated the Ca2+i reduction in VSMCs, suggesting the autocrine and paracrine effects of EDRF on ECs and VSMCs, respectively. However, neither indomethacin, superoxide dismutase, nor neutralizing monoclonal antibody to endothelin-1 altered the second responses. Thus, two-dimensional Ca2+i image analysis of ECs and VSMCs in coculture enabled direct visualization of the EDRF actions in ECs and VSMCs and their modifications.

Adenosine Triphosphate↗
PubMed1992

Pharmacological aspects of arthritis induced by a muramyl dipeptide analogue in rats.

Fourteen consecutive daily subcutaneous injections of 4 mg/kg of the muramyl dipeptide analogue MDP-Lys(L18) into rats caused arthritis characterized by swelling of the tarsal joint, increases in lymphocytes and monocytes in the peripheral blood, and elevated serum immunoglobulin G (IgG). The present study was performed to evaluate the effects of indomethacin, phenylbutazone, dexamethasone, D-penicillamine, aurothioglucose, cyclophosphamide and cyclosporin A on this arthritis. Administration of indomethacin, phenylbutazone or dexamethasone inhibited the development of the tarsal joint swelling, suggesting that prostaglandins may be involved in the pathogenesis of the arthritis. Cyclophosphamide reduced the arthritis, together with decreases in the lymphocyte count and the serum IgG level. Cyclosporin A worsened the arthritis in a dose-dependent manner and increased the neutrophil count without raising the serum IgG level, but inhibited the induction of adjuvant arthritis in rats with Mycobacterium bacilli. MDP-Lys(L18) may therefore induce arthritis differing in mechanism from adjuvant arthritis.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1992

Transport of procainamide in a kidney epithelial cell line LLC-PK1.

Transport of procainamide, an anti-arrhythmic drug, was investigated in LLC-PK1 kidney epithelial cell line. The uptake of procainamide by LLC-PK1 monolayers cultured in plastic dishes was temperature-dependent, saturable and inhibited by organic cations such as cimetidine and N-acetylprocainamide. An aminocephalosporin antibiotic, cephalexin, also inhibited procainamide uptake, but an organic anion, p-aminohippurate, did not. The uptake of procainamide was greater at an alkaline external pH than at an acidic pH. In addition, procainamide uptake increased when intracellular pH was decreased and the uptake decreased when the intracellular pH was increased by ammonium chloride treatment, indicating the involvement of an H+/procainamide antiport system in apical membrane. The basolateral to apical flux of procainamide across LLC-PK1 monolayers cultured on permeable supports was 2.5-times larger than the apical to basolateral flux, and only the former process was inhibited by other organic cations. These findings suggest that LLC-PK1 cells can transport procainamide by the organic cation transport system and that procainamide is transported unidirectionally from basolateral to apical side across the cell monolayers.

Animals↗
PubMed1992

Comparative study of the sugar chains of factor VIII purified from human plasma and from the culture media of recombinant baby hamster kidney cells.

The asparagine-linked sugar chains of blood coagulation factor VIII preparations purified from human plasma of blood group A donors and from the culture media of recombinant BHK cells were released as oligosaccharides by hydrazinolysis. These sugar chains were converted to radioactive oligosaccharides by reduction with sodium borotritide and separated into neutral and acidic fractions by paper electrophoresis. Most of the acidic oligosaccharides were converted to neutral ones by sialidase digestion, indicating that they are sialyl derivatives. The neutral and sialidase-treated acidic oligosaccharides were fractionated by serial chromatography on immobilized lectin columns and Bio-Gel P-4 column. Structural study of each oligosaccharide by sequential exo- and endoglycosidase digestion and by methylation analysis revealed that both factor VIII preparations contain mainly high mannose-type and bi-, tri-, and tetra-antennary complex-type sugar chains. Some of the biantennary complex-type sugar chains from human plasma factor VIII contain blood group A and/or H determinant, while those from recombinant product do not. Some of the bi-, tri- and tetra-antennary complex-type sugar chains of the recombinant factor VIII contain the Gal alpha 1----3Gal group. A small number of the triantennary complex-type sugar chains from both preparations was found to contain the Gal beta 1----4(Fuc alpha 1----3)GlcNAc beta 1----4 (Gal beta 1----4GlcNAc beta 1----2)Man group. Studies of pharmacokinetic parameters of the recombinant factor VIII infused into baboons revealed that its half-life in blood circulation is similar to that of plasma derived factor VIII, suggesting that the oligosaccharide structural differences between them do not affect the fate of factor VIII in vivo.

Animals↗
PubMed1992

Activation of kappa-opioid receptors inhibits depolarisation-evoked exocytosis but not the rise in intracellular Ca2+ in secretory nerve terminals of the neurohypophysis.

Nerve endings of the magnocellular neurohypophysial neurones possess kappa-opioid receptors. Using a preparation of isolated terminals from the neurohypophysis we studied kappa-opioid effects on secretion of oxytocin and vasopressin and on intracellular Ca2+ concentration ([Ca2+]i) measured fluorimetrically or using digital video imaging with Fura-2. The dihydropyridine Ca(2+)-channel antagonist nicardipine reduced [Ca2+]i responses to K(+)-depolarisation (30-40 mM K+) by 55-75% and inhibited evoked secretion of oxytocin and vasopressin to a similar extent. The selective kappa-receptor agonist D-Pro10 Dynorphin A 1-11 (DPDYN) substantially inhibited K+ evoked secretion of oxytocin by 40-90% and secretion of arginine vasopressin (AVP) by 20-50%. DPDYN caused only a 10% reduction in the average total population [Ca2+]i response to K+ depolarisation. No sub-population of inhibitory responses was observed when samples of individual terminal [Ca2+]i responses were examined with imaging. Although kappa-receptors are coupled to Ca(2+)-channels at neuronal somata our data suggest that alternative effector mechanisms operate in these secretory nerve endings.

Animals↗
PubMed1992

[Multi-directional stereo viewing of MR angiography].

A new method was developed to display MR angiographic images. Nine MR angiographic images rotated along the cranio-caudal axis with ten incremental degree were constructed. These images were printed from left-anterior-oblique view to give a stereoscopic effect. With the stereoscopic viewing of these images, multiple stereoscopic images with different viewing directions were observed at once. Anatomical relationships of the vessels were more clearly understood than usual stereoscopic viewing. This multi-directional stereo viewing method is useful to display not only the MR angiographic images but also other multi-viewing techniques.

Blood Vessels↗
PubMed1992

Identification of a 80 kDa calmodulin-binding protein as a new Ca2+/calmodulin-dependent kinase by renaturation blotting assay (RBA).

We surveyed rabbit brain cytosol for a new Ca2+/calmodulin (CaM)-dependent kinase. The renaturation blotting assay (RBA) exploits the ability of blotted SDS-denatured proteins to regain enzymic activity after guanidine treatment. Using RBA, we found that the eluate of rabbit brain cytosol from a CaM affinity column contains at least four electrophoretically distinct protein kinase bands which were autophosphorylated in a Ca2+/CaM-dependent manner. The 49 kDa band and the 60 kDa band were alpha and beta subunit of CaM kinase II, and the 42 kDa band was presumed to be CaM kinase I, but the 80 kDa band could not be attributed to any reported Ca2+/CaM-dependent protein kinases. The 80 kDa protein kinase was isolated by three-step chromatography. We examined the phosphorylation of exogenous substrates by 80 kDa protein kinase, and histone IIIs and myosin light chain were phosphorylated in a Ca2+/CaM-dependent manner. W-7, a specific inhibitor for calmodulin, inhibited this kinase activity, but KN-62, a specific inhibitor for CaM kinase II, had no effect on this protein kinase activity. Autoradiography using boiled rabbit brain homogenate as substrate showed three intrinsic substrates (80 kDa, 60 kDa and 42 kDa), which were phosphorylated in a Ca2+/CaM-dependent manner. These findings suggest that a new Ca2+/CaM-dependent protein kinase could be identified by the RBA.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

In vitro translocation of secretory proteins possessing no charges at the mature domain takes place efficiently in a protonmotive force-dependent manner.

The effect of charges existing on the mature domain of secretory proteins on the efficiency and protonmotive force dependence of translocation into everted membrane vesicles of Escherichia coli was studied. Model secretory proteins devoid of charges on the mature domain were constructed at the DNA level using proOmpF-Lpp as the starting protein. The chargeless presecretory proteins thus constructed were translocated and processed for the signal peptide much faster than proOmpF-Lpp and the rate of translocation was appreciably enhanced by imposition of the protonmotive force. Not only the membrane potential but also delta pH were effective in stimulating the rate of translocation of the chargeless proteins. The results indicate that the mature domain does not have to be charged for the secretory translocation and that the major requirement of the protonmotive force for the secretory translocation is not for the movement, including an electrophoretic one, of charged regions of the mature domain. All of the proOmpF-Lpp derivatives thus constructed were translocated efficiently into everted membrane vesicles in a SecA-dependent manner, irrespective of their size. The mature domain of the smallest one was 45 amino acid residues in length. Contrary to the views previously presented by other workers, these results suggest that there is no sharp boundary at the reported regions for the translocation of presecretory proteins across the cytoplasmic membrane or for the requirement of SecA.

Adenosine Triphosphatases↗
PubMed1992

Electron microscopic study of brain capillaries in cerebral edema from fulminant hepatic failure.

Cerebral edema is a serious complication of the encephalopathy in fulminant hepatic failure. It is a major cause of death. The mechanisms responsible for its formation are unclear, and the aim of this study was to investigate the ultrastructural appearance of brain capillaries by scanning electron microscopy. Samples of cerebral cortex were obtained immediately after death from nine patients with fulminant hepatic failure (seven cases due to acetaminophen overdose, one caused by hepatitis B and one caused by non-A, non-B hepatitis) by needle biopsy at the site of insertion of an extradural pressure transducer to monitor intracranial pressure. The intercellular tight junctions between capillary endothelial cells were intact. The endothelial cells were swollen, with increased numbers of vesicles and vacuoles. The basement membranes were enlarged and vacuolized and the pericytes had increased numbers of vesicles and vacuoles, indicative of passage of fluid by this route. Marked intracellular swelling of the perivascular astroglial foot processes was present. Thus mainly cytotoxic mechanisms, with cellular swelling, and to a lesser extent vasogenic mechanisms, with altered blood-brain barrier permeability, appear to be involved in the cerebral edema of fulminant hepatic failure.

Acetaminophen↗
PubMed1992

A YIGSR-containing novel mutein without the detrimental effect of human TNF-alpha of enhancing experimental pulmonary metastasis.

The injection of B16F10 melanoma cells with recombinant human tumor necrosis factor alpha (TNF-alpha) into the tail vein of C57BL/6 mice resulted in 2- to 25-fold more metastatic foci in the lungs than the injection of tumor cells alone. Clearly, TNF-alpha significantly enhanced experimental tumor metastasis. Furthermore, it enhanced the metastasis of Lewis lung carcinoma cells. In contrast, a mutein of TNF-alpha, designated as F4236, having the cell-adhesive sequence (Tyr-Ile-Gly-Ser-Arg) at the N-terminus of the TNF molecule did not enhance metastasis, but rather exhibited similar antitumor activity to wild-type TNF-alpha in fibrosarcoma-bearing mice.

Amino Acid Sequence↗
PubMed1992

Stress-response (heat-shock) protein 72 expression in tumors of the central nervous system: an immunohistochemical investigation.

This report deals with the expression of stress-response (heat-shock) protein 72 (srp 72) in a series of 95 primary human brain tumors and 21 carcinoma metastases to the central nervous system (CNS). Immunohistochemical procedures were employed; cells of the human cervical cancer line HeLa S3 were used as positive controls. The protein was detected in 14/22 meningiomas and in 6/13 glioblastomas. Tumor cells expressing srp 72 were also found in 4/17 astrocytomas, 2/9 pituitary tumors, 2/14 primitive neuroectodermal tumors and 1/10 medulloblastomas. Whereas the majority (8/10) of the breast carcinoma metastases had tumor cells that expressed srp 72, only 2/11 lung tumor metastases were positively stained. These results document srp 72 expression by a variety of primary and metastatic tumors of the CNS.

Antibodies, Monoclonal↗
PubMed1992

Treatment of hepatocellular carcinoma with a CDDP-epirubicin-lipiodol suspension: a pilot clinico-pharmacological study.

Lipiodol injection is a useful method for detecting liver tumors, especially hepatocellular carcinoma (HCC). We therefore prepared and tested a new emulsion of lipiodol containing epirubicin and cis-diammine-dichloroplatinum (CDDP), drugs that are very effective against HCC. This CDDP-epirubicin-lipiodol suspension (CELS) was injected into 18 HCC patients via a celiac angiographic catheter. In 11 of these patients, CELS was followed by transcatheter arterial embolization (TAE) therapy. Clinical and pharmacological investigations were performed in all 18 patients, and the following results were obtained. CELS is pharmacologically and chemically stable, and both the results of the dissolution test and the serum levels of these two drugs indicate that slow release can be obtained. After the injection of CELS, serum levels of AFP and PIVKA-II decreased immediately, and no fatal clinical side effects were encountered. Although no statistically significant difference was observed, the survival (Kaplan-Meier method) of patients injected with CELS in the presence or absence of TAE therapy can be estimated to be much longer than that of patients receiving CDDP-lipiodol suspension injection in the presence (16 patients) or absence (6 patients) of TAE therapy. A combination of CELS injection and TAE therapy might be effective and useful for the treatment of HCC.

Aged↗
PubMed1992

Analysis of prognostic factors in patients with hepatocellular carcinoma treated by transcatheter arterial embolization.

We studied 240 cases of unresected hepatocellular carcinoma (HCC) using Cox's proportional hazard model to elucidate which factors would be closely related with the survival period after treatment by transcatheter arterial embolization (TAE) in the presence or absence of iodized oil. The results were as follows. The cumulative survival values obtained after TAE were 67.5% for 1 year, 32.0% for 2 years, and 20.5% for 3 years. The most significant prognostic factor was the degree of extension of tumor embolus in the portal vein or its branch. The tumor extension and the tumor type were also important factors. Age, sex, and AFP, HBsAg, and HCV Ab values were not useful as prognostic factors. This study provides a rational background for the selection of treatment for HCC. Furthermore, knowledge of the prognostic factors is useful for the management of patients, particularly in maintaining their good quality of life.

Adult↗