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K Murakami

Publications and source records attributed to K Murakami.

At least 937 records · Page 52Linked to original sources
PubMed1989

[Long-term results of intra-arterial infusion therapy using cis-DDP (CDDP) in thoracic esophageal cancer].

The effects of intra arterial infusion therapy using CDDP for patients with thoracic esophageal cancer were investigated. From June 1984 to December 1988, 25 of 146 resected patients with thoracic esophageal cancer underwent preoperative therapy in our institute. All of these patients it was suspected preoperatively that their chief lesion had invaded to the aorta, trachea or main bronchi. Preoperative radio-chemotherapy with intra arterial infusion therapy was given to 10 of 25 patients (A group), and without intra arterial infusion therapy to 15 of 25 patients (B group). CDDP 75 mg was infused into the proper esophageal artery. In A group, 7 of 10 (70%) showed moderately or marked effects in histologic study, although in B group, only 4 of 15 (27%) did so. As for long-term results, the 2-year survival rates were 50% in A group and 13% in B group (Kaplan-Meier method. Preoperative intra arterial infusion therapy using CDDP with radio-chemotherapy showed markedly better effects in histologic study and survival rates than preoperative radio-chemotherapy without intra arterial infusion therapy. We consider that this therapy is very useful for controlling the local lesion in advanced esophageal cancer.

Cisplatin↗
PubMed1988

Purification by hydrophobic chromatography of soluble cytochrome b5 of human erythrocytes.

Soluble cytochrome b5 of human erythrocytes was purified very effectively by hydrophobic chromatography using a butyl-Toyopearl 650 column. Cytochrome b5 was adsorbed tightly on the column in the presence of 60% saturated ammonium sulfate, and was eluted at 40% saturation of ammonium sulfate in the elution buffer. The chromatography gave a good yield of cytochrome b5 of the highest purity so far reported as estimated from the 414 nm to 280 nm absorbance ratio of the oxidized form of the cytochrome b5. The value obtained with the cytochrome b5 purified in this study was 6.57, and is higher than the previously reported highest value of 6.4 (Hultquist, D.E., Dean, R.T. and Douglas, R.H. (1974) Biochem. Biophys. Res. Commun. 60, 28-34). Spectral properties including molecular absorption coefficients were determined using the cytochrome b5 purified by this method.

Amino Acids↗
PubMed1988

Reconstitution of mitochondrial protein transport with purified ornithine carbamoyltransferase precursor expressed in Escherichia coli.

Ornithine carbamoyltransferase (OTC; subunit, 36,000 Da) is initially synthesized as a precursor (pOTC) with a transient NH2-terminal presequence of 32 amino acid residues and imported posttranslationally into the mitochondrial matrix. The rat pOTC was synthesized in Escherichia coli using an expression vector containing a thermoinducible lambda pL promoter. The recombinant pOTC represented 5-10% of the total bacterial protein and was present in the precipitate of the disrupted bacteria. The precipitate was washed and pOTC was extracted with 8 M urea or 0.1% cetyltrimethylammonium bromide. The extracted pOTC was essentially homogeneous, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified pOTC was cleaved to the intermediate-sized product of 37,000 Da by a processing protease partially purified from the matrix fraction of rat liver mitochondria. The purified recombinant pOTC, but not the mature form of OTC synthesized in E. coli and purified, competed with the in vitro-synthesized, radiolabeled pOTC for uptake and processing by the isolated rat liver mitochondria. The radiolabeled and purified recombinant pOTC could be imported into the isolated mitochondria and processed to the mature form in an energy- and rabbit reticulocyte lysate-dependent manner. When the purified pOTC was subjected to sucrose gradient centrifugation, it sedimented as a large aggregate of greater than 60 S in the absence of reticulocyte lysate, whereas it sedimented as a complex of about 5 S in the presence of the lysate. These observations together with our previous results indicate that a protein factor(s) present in the lysate interacts with pOTC and holds it in an import-competent form.

Animals↗
PubMed1988

Effects of sodium nitroprusside on cytosolic calcium level in vascular smooth muscle.

The inhibitory effect of sodium nitroprusside on the cytosolic Ca2+ level ([Ca2+]cyt), measured simultaneously with contraction by means of a fluorescence dye, fura-2, and on the 45Ca2+ uptake was tested in the isolated rat aortic smooth muscle. Norepinephrine increased muscle tension, 45Ca2+ uptake and [Ca2+]cyt. In a Ca2+-deficient solution, norepinephrine transiently increased muscle tension and [Ca2+]cyt. Sodium nitroprusside inhibited all changes induced by norepinephrine although the inhibition of [Ca2+]cyt was less than that of muscle contraction. Sodium nitroprusside also inhibited the high K+-induced contraction at concentrations higher than those needed to inhibit norepinephrine-induced contraction. Inhibition of the high K+induced contraction was accompanied by a small decrease in [Ca2+]cyt and a smaller decrease in 45Ca2+ uptake. Methylene blue antagonized, and M&B 22,948 potentiated the inhibitory effect of sodium nitroprusside. These results suggest that sodium nitroprusside has multiple sites of action. At relatively low concentrations, sodium nitroprusside could inhibit the Ca2+ influx and Ca2+ release. At relatively high concentrations, this inhibitor could also augment Ca2+ sequestration and decrease the sensitivity of contractile elements to Ca2+.

Animals↗
PubMed1988

Evaluation of cryopreservation techniques of pancreatic fragments and islets in vitro and in vivo.

We evaluated cryopreservation techniques for pancreatic fragments and islets using rat tissue. After equilibration in 10% dimethyl sulfoxide (Me2SO), the tissue was frozen in a programmable freezer at 1 degree C/min down to -40 degrees C and at 3 degrees C/min down to -71 degrees C. The islets, when thawed, released abundant insulin in the presence of as little as 3.3 mM glucose, much more so than non-frozen islets did. Three additional procedures, prefreezing and post-thawing culture and the stepwise dilution of the Me2SO, lowered the non-specific insulin release of the thawed islets and improved their insulin response to 16.7 mM glucose. Thawed pancreatic fragments subjected to these additional procedures, transplanted into the peritoneal cavity of streptozotocin-induced diabetic rats, reduced their hyperglycemia significantly. The thawed fragments and islets did not differ from their corresponding non-frozen controls in 3H-leucine incorporation. The maintenance of tissue function was not satisfactory. However, our observations indicate that culturing pancreatic tissue before freezing and after thawing and the stepwise dilution of the cryoprotective agent reduce the damage induced by freezing the tissue.

Animals↗
PubMed1988

A kinetic study of the inhibition of yeast AMP deaminase by polyphosphate.

Inorganic pyrophosphate and polyphosphates have acted as potent inhibitors of purified AMP deaminase (EC 3.5.4.6) from yeast: the activity fell to a definite limit with the increase in the concentration of the inhibitor. The effect of polyphosphate was largely on the maximal velocity of the enzyme with some decrease in affinity. The cooperative effect of AMP, analyzed in terms of a Hill coefficient, remained at 2 in the absence and presence of polyphosphate. Binding of polyphosphate to the enzyme showed no cooperativity. The inhibition of AMP deaminase by polyphosphate can be qualitatively and quantitatively accounted for by the partial mixed-type inhibition mechanism. Both the Ki value for the inhibitor and the breakdown rate of the enzyme-substrate-inhibitor complex are dependent on the chain length of polyphosphate, suggesting that the breakdown rate of the enzyme-substrate-inhibitor complex is regulated by binding of polyphosphate to a specific inhibitory site.

AMP Deaminase↗
PubMed1988

Role of N-linked oligosaccharides attached to human renin expressed in COS cells.

One or both of two putative N-glycosylation sites (at asparagine-5 and -75) of human renin was eliminated by amino acid replacement of the asparagine residue with an alanine residue using site-directed mutagenesis. The three glycosylation-deficient renins (Asn-5, Asn-75, Asn-5 and -75 mutants) were expressed in COS cells and secreted into the conditioned media. The secreted amounts of the three mutants were different from one another, although the mutant and wild-type renins had practically the same specific activity. An Asn-5 and -75 mutant which did not contain any glycosylation sites was unstable in the medium, suggesting that the N-linked oligosaccharides play an important role in stabilization of human renin.

Amino Acid Sequence↗
PubMed1988

Structure of the rat renin gene.

We have isolated the renin gene from a Sprague-Dawley rat genomic library and determined its complete nucleotide sequence. The single rat renin gene is approximately 11,000 bases in length and consists of nine exons and eight introns. The amino acid sequence predicted from the genomic sequence indicates that the rat renin precursor consists of 402 amino acid residues, and shows 85%, 82% and 68% homology to the mouse Ren-1 and Ren-2, and human renins, respectively. The canonical promoter "TATA" boxes, TATAAA and TAATAA, are found 27 and 57 base-pairs upstream from the putative cap site, respectively. Several attractive regulatory sequences analogous to glucocorticoid, estrogen receptor-binding sites, cAMP-responsive element and SV40 enhancer core sequences were noted in the 5'-flanking region of the gene. In the first intron, segments with an average size of 38 base-pairs containing a NcoI site are present at 46 tandem repeats within 1710 base-pairs. A "CA" element consisting of (CA)27 was identified in intron 3. Furthermore, intron 8 contains a sequence that shows about 93% homology to that of the neuronal identifier sequence.

Amino Acid Sequence↗
PubMed1988

Immunoaffinity purification of human prorenin produced in Chinese hamster ovary cells.

A simple immunoaffinity column chromatographic procedure is described whereby recombinant human prorenin secreted from Chinese hamster ovary cells may be isolated in a high state of purity from serum-free culture medium. Prorenin thus purified has been characterized by SDS-polyacrylamide gel electrophoresis and by partial sequence analysis which has revealed the expected N-terminal sequence. Trypsin treatment gives rise to renin, and reversible acid activation has also been demonstrated for the recombinant zymogen.

Ammonium Sulfate↗