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Biomedical subjects

K Tsukada

Publications and source records attributed to K Tsukada.

At least 271 records · Page 15Linked to original sources
PubMed1986

Increased activities of thymidine kinase isozymes in human mammary tumours.

Thymidine kinase, the enzyme in the pyrimidine salvage pathway, and its isozymes were examined in 10 specimens of normal mammary gland, 10 fibroadenomas and 11 adenocarcinomas in human breasts. The average thymidine kinase activities in fibroadenomas and adenocarcinomas were about 3 and 8 times that in normal mammary gland. The mammary thymidine kinase isozymes were separated into two types by diethylaminoethyl (DEAE) cellulose column chromatography. The activity of the thymidine kinase isozyme eluted with 0.1 M sodium chloride in buffer was twofold higher in fibroadenomas and fourfold higher in adenocarcinomas than that in normal tissue. In adenocarcinomas, but not fibroadenomas, the activity of the other isozyme eluted with buffer alone was increased to 22-fold that in normal tissues. As the activity of the latter isozyme was not affected by deoxycytidine triphosphate, it may be involved closely in DNA replication.

Adenocarcinoma↗
PubMed1986

Electroencephalography in minor head injury in children.

EEG and CT scans of 280 cases of minor head injury in children under 15 years of age were studied. Abnormality on initial EEG was shown in 42.5%. Those who lost consciousness had a higher incidence of abnormality than those who did not, and it was higher between 4 and 13 years of age. The sleep state has much influence on the finding. The patients should be awake or in a light sleep stage. The most frequent abnormality was slow waves, seen predominantly in the occipital regions, and which tended to disappear more easily than the paroxysmal ones. The EEGs became or remained normal in 95%, excluding incompletely followed-up cases. There was no case of post-traumatic epilepsy in our series, but 4 cases of post-traumatic early convulsions, in which the EEGs were variable. CT scan disclosed abnormality in 6%.

Adolescent↗
PubMed1986

Isozymes of S-adenosylmethionine synthetase from rat liver: isolation and characterization.

S-Adenosylmethionine synthetase exists in at least two distinct forms, alpha- and beta-forms, in adult liver. The beta-form was purified to homogeneity from the soluble fraction of rat liver with a yield of about 10%. An antiserum directed against the purified beta-form from rat liver was prepared by injecting the purified enzyme into a rabbit. Ouchterlony double diffusion analysis and immunochemical titrations revealed that the isozymes, alpha- and beta-forms, are identical. Thus, the alpha-form was isolated from rat liver as a single protein using immunoaffinity chromatography against the beta-form. The molecular weights of the beta- and alpha-forms were determined to be 48,000 each by sodium dodecyl sulfate disc gel electrophoresis, and about 100,000, and 200,000, respectively, by Sephacryl S-200 gel filtration. These results indicate that the beta-form consisted of two subunits of 48,000 daltons and the alpha-form of four subunits of 48,000 daltons. The sedimentation coefficient was calculated to be 5.5S for the beta-form and 8.0S for the alpha-form.

Animals↗
PubMed1986

Myocarditis with myocardial infarction like findings in a 3-year old girl.

A 3 year-old Japanese girl had an acute onset associated with vomiting. The electrocardiogram (ECG) indicated changes similar to those of acute myocardial infarction (MI); there was no past history of kawasaki disease. Selective coronary angiography taken on the 28th day of illness revealed no abnormality. Thallium 201 scintigraphy was also performed and it revealed that the area of absent myocardial uptake was in the anterior wall. In serological findings, antibody titers against Coxsackie B-3 virus had risen significantly; therefore acute myocarditis caused by Coxsackie B-3 virus infection was diagnosed.

Antibodies, Viral↗
PubMed1986

[Retroperitoneal malignant fibrous histiocytoma--report of a case].

A 52-year-old man with a three-month history of left epigastralgia and body weight loss was referred to us for a possible abdominal tumor in March 1984. Retroperitoneal malignant tumor was suspected by ERCP, angiography, US, and CT. At laparotomy, a child's-head-sized retroperitoneal tumor, which weighed 1,800 g, was resected. Pathological examination revealed the diagnosis of retroperitoneal malignant fibrous histiocytoma (MFH). He died because of recurrence in the retroperitoneum six months after the operation. We selected 26 Japanese cases of retroperitoneal MFH and discussed their clinical findings and prognosis.

Female↗
PubMed1985

Metabolism of S-adenosylmethionine in rat hepatocytes: transfer of methyl group from S-adenosylmethionine by methyltransferase reactions.

Treatment of rats with a methionine diet leads not only to a marked increase of S-adenosylmethionine synthetase in liver, but also to the increase of glycine, guanidoacetate and betaine-homocysteine methyltransferases. The activity of tRNA methyltransferase decreased with the increased amounts of methionine in the diets. However, the activities of phospholipids and S-adenosylmethionine-homocysteine methyltransferases did not show any significant change. When hepatocarcinogenesis induced by 2-fluorenylacetamide progresses, the activities of glycine and guanidoacetate methyltransferases in rat liver decreased, and could not be detected in tumorous area 8 months after treatment. The levels of S-adenosylmethionine in the liver also decreased to levels of one-fifth of control animals at 8 months. The uptake and metabolism of [methyl-3H]-methionine and -S-adenosylmethionine have been investigated by in vivo and isolated hepatocytes. The uptake of methionine and transfer of methyl group to phospholipid in the cells by methionine were remarkably higher than those by S-adenosylmethionine. These results indicate that phospholipids in hepatocytes accept methyl group from S-adenosylmethionine immediately, when it is synthesized from methionine, before mixing its pool in the cells.

Animals↗
PubMed1985

Inhibition of DNA polymerase alpha, DNA polymerase beta, terminal deoxynucleotidyl transferase, and DNA ligase II by poly(ADP-ribosyl)ation reaction in vitro.

Incubation of DNA polymerase alpha, DNA polymerase beta, terminal deoxynucleotidyl transferase, or DNA ligase II in a reconstituted poly(ADP-ribosyl)ating enzyme system markedly suppressed the activity of these enzymes. Components required for poly(ADP-ribose) synthesis including poly(ADP-ribose) polymerase, NAD+, DNA, and Mg2+ were all essential for the observed suppression. Purified poly(ADP-ribose) itself, however, was slightly inhibitory to all of these enzymes. Furthermore, the suppressed activities of DNA polymerase alpha, DNA polymerase beta, and terminal deoxynucleotidyl transferase were largely restored (3 to 4-fold stimulation was observed) by a mild alkaline treatment, a procedure known to hydrolyze alkaline-labile ester linkage between poly(ADP-ribose) and an acceptor protein. All of these results strongly suggest that the four nuclear enzymes were inhibited as a result of poly(ADP-ribosyl)ation of either the enzyme molecule itself or some regulatory proteins of these enzymes.

Animals↗
PubMed1985

Biosynthesis of mammalian DNA ligase.

A monospecific antibody against calf thymus DNA ligase composed of a single polypeptide with Mr = 130,000 cross-reacts with rodent and calf thymus DNA ligases. The antibody precipitates a single Mr = 200,000 polypeptide from detergent lysates of [3H] leucine-labeled mouse Ehrlich tumor cells and calf thymocytes. Pulse-chase experiments show that the Mr = 200,000 polypeptide in Ehrlich tumor cells has a half-life of about 0.5 h. In addition to the Mr = 200,000 polypeptide, a Mr = 130,000 polypeptide is detected in the partially purified enzyme preparations from radiolabeled Ehrlich tumor cells. These results suggest that DNA ligase is synthesized in mammalian cells as a Mr = 200,000 polypeptide and that the Mr = 200,000 polypeptide is degraded to a Mr = 130,000 polypeptide by a limited proteolysis in vitro.

Animals↗
PubMed1985

Ultrasonic aid in transvenous instrumental dilatation for patients with membranous stenosis of the hepatic portion of the inferior vena cava.

We report two cases of a membranous stenosis of the hepatic portion of the inferior vena cava. Membranotomy was performed with a specially designed instrument similar to a Tubbs' dilator following balloon membranotomy. During the procedures, ultrasonographic observations were made and this technique was confirmed to be effective for proper placing of a balloon and a dilator in the stenotic portion. Follow-up evaluation of the procedures was also feasible with this ultrasonic aid.

Angioplasty, Balloon↗
PubMed1985

Immunohistochemical and biochemical studies on DNA ligase from a rat liver parenchymal cell line.

We have recently obtained a monospecific antibody against calf thymus DNA ligase composed of a single Mr = 130,000 polypeptide. Immunohistochemical studies using the antibody and immunoperoxidase detection methods indicated that DNA ligase in a rat liver parenchymal cell line (BB) is localized essentially in nucleus. The specific activity of DNA ligase from growing BB cells was more than 10-fold higher than that from rat hepatocytes. The molecular forms of DNA ligase in these cell-free extracts were also analyzed.

Animals↗
PubMed1984

The uptake of creatine by various tissues from a mouse bearing tumor cells.

The activity of guanidoacetate methyltransferase has been measured in various tissues of mice and tumor cells. The creatine levels in tumor cells are high, although guanidoacetate methyltransferase activity was not detected. To confirm these results, labeled creatine was synthesized by guanidoacetate and its methyltransferase in the presence of S-adenosyl-L-[methyl-3H]methionine, and administered to a mouse with or without tumor cells. High levels of the uptake of the creatine were observed in tumor cells, intestine, heart and muscle of the mouse injected with [3H]creatine into a tumor-bearing mouse. These organs, however, had no detectable activity of guanidoacetate methyltransferase. Labeled creatine phosphate in the tissue was less than 10% compared to total labeled creatine.

Animals↗
PubMed1984

Increased activity of thymidine kinase isozyme in human colon tumor.

Thymidine kinase (TK), the salvage pathway enzyme, and its isozymes were examined in normal mucosa and carcinoma of the colon in 13 patients. In colon tumor TK activity increased to 328% of activity of normal colon. The colon TK isozymes were separated from the normal mucosa and carcinoma by DEAE-cellulose column chromatography. The TK isozyme eluted from the column by the elution buffer alone without NaCl was markedly higher (12-fold) in activity in carcinoma than in normal mucosa of the colon and is not affected by dCTP. The TK isozyme unaffected by dCTP has also been reported to be clearly involved in DNA synthesis. This isozyme, whose molecular weight is 100 000 by means of high performance liquid chromatography, is thought to be involved in DNA replication. The results indicate the applicability of the molecular correlation concept to carcinogenesis of colon.

Aged↗
PubMed1984

Changes in the activities of S-adenosylmethionine synthetase isozymes from rat liver with dietary methionine.

The activities of S-adenosylmethionine synthetase isozymes in liver were measured after rats received a diet containing excess methionine. The activity of the alpha-form increased with increasing methionine content in the diet, and reached 4-5 fold after 6 days on a 3% methionine diet. However, the activity of the beta-form showed only a 1.5 fold increase. The activity of the gamma-form in kidney showed no significance change.

Animals↗
PubMed1984

The alpha-form of S-adenosylmethionine synthetase isozymes from liver is principally functional.

Treatment of rats with an ethionine plus adenine or a methionine diet leads not only to a marked increase of the alpha-form isozyme of S-adenosylmethionine synthetase in liver, but also to the accumulation of comparable amounts of S-adenosylethionine and S-adenosylmethionine in liver. Transplantation of ascites tumor cells into mice leads to a marked increase only of the beta-form isozyme in the host liver, but the levels of S-adenosylmethionine do not significantly change in liver.

Adenine↗