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Biomedical subjects

K Enomoto

Publications and source records attributed to K Enomoto.

At least 109 records · Page 6Linked to original sources
PubMed1996

[A randomized controlled study of maintenance therapy with (2"R)-4'-O-tetrahydropyranyladriamycin for advanced and recurrent breast cancer. Clinical Study Group of THP for Breast Cancer in Japan].

We conducted a randomized controlled study to evaluate the clinical usefulness of (2"R) -4'-O-Tetrahydropyranyladriamycin (THP)-based combination therapy subsequent to induction therapy which was consisted with THP, 5'-DFUR, and CPA in the treatment of advanced or recurrent breast cancer. In maintenance therapy, Arm C received CPA and TAM, and Arm T received these two drugs plus THP. Survival time of 50% for all cases in which maintenance therapy was conducted was 26.9 months in Arm T and 20.9 months in Arm C, showing no significant difference by the log-rank test (p = 0.64). Survival time in all cases in which therapy had been completed was 54.6 months in Arm T and 28.1 months in Arm C, showing a significant difference by the log-rank test (p = 0.03) although the number of cases was few. A few cases showed a decrease in total leukocyte count to below 2,000/mm3 at the time of induction therapy, but this was transient in all cases. No significant difference in count was noted between two arms at the time of maintenance therapy. However, many cases in Arm T showed decreased total leukocyte count and hemoglobin content, and thrombocytopenia. These results suggest that combination therapy including THP conducted as maintenance therapy after induction is useful in the prolongation of survival time in patients with advanced or recurrent breast cancer.

Adult↗
PubMed1996

[p53 gene mutations in the human lung carcinoma].

The p53 mutations in the reported 243 lung cancers and our 59 cases were analyzed. The common base substitutions found in the lung cancer were G to T transversion (35%), C:G to T:A (26%) and A:T to G:C transitions (11%). Four types of the hot spot, 1) G to T transversion, 2) A to G transition in ApT site, 3) C to T transition in CpG site and 4) mix of the transversion and transition were identified. It is suggested that A to G transition at ApT site in the non-transcribed strand may be a new hot spot in the p53 gene in lung carcinoma. We also show that microscopic selection of cancer cells will facilitate the detection of p53 mutations in adenocarcinomas.

Genes, p53↗
PubMed1996

[Spinal intramedullary cavernous angioma associated with hematomyelia: case report with sequential MRI follow-up and histological verification of hematoidin deposits].

A 61-year-old woman first experienced sudden lower back and right leg pain 3 years prior to surgery. At this time, MRI showed an intramedullary cavernous angioma at Th10-11 with central T2 high and peripheral T2 low signal intensity. However, she completely recovered in two weeks. Four days prior to the present admission (day of the second hemorrhage), she again experienced severe lower back and right leg pain, followed by complete paralysis of the right leg. Despite vigorous medical treatment including administration of steroid, hemostatics and glycerol, her condition became aggravated with complete paraplegia and loss of sphincter control by the 4th hospital day. MRI taken two days after the second hemorrhage showed an increase of peritumoral T2 hypointensity and another area of T2 hypointensity in the lumbar spinal cord at L1-Th12 with cord swelling. MRI 13 days after the second hemorrhage showed that these areas of T2 hypointensity had changed to T1 and T2 hyperintensity suggesting conversion of deoxyhemoglobin to methemoglobin. Subsequent MRI showed longitudinal punctuate propagation of methemoglobin from the angioma down to the lumbar enlargement and into the conus medullaris, where a 30 x 6 mm spindle-shaped area of T1 and T2 hyperintensity indicating hematomyelia had formed. Total removal of the angioma was followed by gradual recovery and decrease in the size and signal intensity of the hematomyelia. Histopathological examination demonstrated the typical features of cavernous angioma with deposition of hematoidin. Propagation of extravasated blood from the ruptured thoracic cavernoma to the conus medullaris, with splitting of spinal cord nerve fibers, was demonstrated by MRI.

Bilirubin↗
PubMed1995

Comparison of p53 gene abnormalities in bilateral and unilateral breast cancer.

BACKGROUND: The results of recent studies have suggested that p53 gene abnormalities are associated with carcinogenesis in several neoplasms. It is believed that bilateral breast carcinomas develop as a result of a different carcinogenetic mechanism and genetic environment from those of unilateral lesions. METHODS: p53 Gene abnormalities in bilateral primary breast cancer were detected by polymerase chain reaction-single strand comformation polymorphism (PCR-SSCP) analysis. A total of 76 paraffin embedded tissue specimens from 38 patients with bilateral primary breast cancer were examined, and 62 patients with unilateral breast cancer were analyzed as control subjects. The bilateral tumors were defined as primary, based on clinical parameters and the presence of an intraductal component. There were 13 patients with synchronous bilateral breast cancer and 25 with metachronous bilateral breast cancer. RESULTS: p53 Gene abnormalities were detected in 50% of the bilateral and 25.8% of the unilateral cases, and the difference was significant (P < 0.01, chi-square test). Abnormalities were detected in 56% of the metachronous cases, representing a much higher incidence than that of the unilateral cases (P < 0.001, chi-square test). The incidence of p53 gene abnormalities in the first and second tumors of the metachronous cases was 44% and 68%, respectively. The percentage of patients with a p53 gene abnormality and positive family history was higher for those with bilateral than with unilateral breast cancer (P < 0.01, chi-square test). CONCLUSION: These findings indicate that the genetic changes and mechanism of carcinogenesis in bilateral and unilateral breast cancer are different.

Adult↗
PubMed1995

Whole-cell analysis of NGK2 (mKv3.1a) K+ channels stably expressed in mouse fibroblast cells.

NGK2 (mKv3.1a) K+ channel cDNA was introduced into mouse B82 fibroblast cells to express in a mammalian system. The NGK2 current in the stably transformed fibroblast cells exhibited a high threshold for activation and slow decay with two components. The data suggest that the NGK2 channel may contribute to slowly inactivating K+ currents observed in excitable and inexcitable cells.

Animals↗
PubMed1995

Modification of frequency augmentation-potentiation by GTP gamma S in the frog neuromuscular junction.

The effect of modifiers of guanine nucleotide-binding proteins (G proteins) on the frequency augmentation-potentiation of transmitter release were studied in the frog neuromuscular junction. Using Genetransfer as a carrier the mean quantal content of the endplate potential increased by penetration of GTP gamma S into the presynaptic nerve terminal. Neither GTP gamma S alone nor carrier alone had any effect. The relationship of log (mean quantal content) versus stimulation frequency changed from a single linear to a dual linear function, suggesting that the immediately releasable pool was modified. GDP beta S + carrier also had similar effects, but was less potent. Aluminium fluoride was without effect. Extracellularly recorded presynaptic nerve action potentials remained unchanged with GTP gamma S + carrier. Also, GTP gamma S + carrier did not affect the action potential nor the cytosolic Ca2+ concentration in differentiated NG108-15 hybrid cells. It is suggested that some smg-type G protein-dependent processes are involved in determining frequency augmentation-potentiation.

Action Potentials↗
PubMed1995

Release of arachidonic acid via Ca2+ increase stimulated by pyrophosphonucleotides and bradykinin in mammary tumour cells.

The relationship between the increase of intracellular Ca2+ and the release of arachidonic acid by bradykinin and pyrophosphonucleotides was studied in cultured mammary tumour cells, MMT060562. Bradykinin, ATP, UTP and UDP induced an increase of intracellular Ca2+ and the release of arachidonic acid from phospholipids into the extracellular fluid. Release of arachidonic acid was also induced by the application of the Ca2+ ionophore, A23187. Liberation of arachidonic acid by bradykinin and ATP was reduced by mepacrine, a blocker of phospholipase A2 and W-7, a calmodulin antagonist. It is suggested that the increase in cytosolic Ca(2+)-induced release of arachidonic acid occurs through activation of calmodulin-dependent phospholipase A2.

Adenosine Triphosphate↗
PubMed1995

Effects of medroxyprogesterone acetate therapy on advanced or recurrent breast cancer and its influences on blood coagulation and the fibrinolytic system.

The effects of medroxyprogesterone acetate (MPA) therapy on advanced or recurrent breast cancer and its influence on blood coagulation and the fibrinolytic system were compared among three different therapy regimens consisting of cyclophosphamide, adriamycin, and 5-fluorouracil (CAF) + MPA and CAF or MPA alone. A clinical response was observed in 42.9% (9/21) of the patients for CAF + MPA, 36.4% (8/22) for CAF and 23.8% (5/21) for MPA alone. No marked thrombosis or its prodromal condition was observed in any group. The effects on the test values for blood coagulation and the fibrinolytic system did not significantly change in the CAF group. However, both AT-III and protein C significantly increased above the normal ranges in the CAF+MPA and MPA groups. Increases in factor X, plasminogen, and alpha 2-plasmin inhibitor/plasmin complex (PIC) and decreases in fibrinogen, tissue plasminogen activator, and D-dimer, were all observed in the MPA and CAF + MPA groups, especially in the MPA group, although these changes remained within the normal ranges. The data indicated that MPA has various influences on blood coagulation and the fibrinolytic system, but these changes did not suggest activation of the blood coagulation system.

Antineoplastic Agents, Hormonal↗
PubMed1995

Increased plasma alpha (1 --> 3)-L-fucosyltransferase activities in patients with hepatocellular carcinoma.

Alpha (1 --> 3)-L-fucosyltransferase (alpha 1,3FT) activity was determined in plasma of patients with chronic liver diseases, namely, chronic hepatitis (CH), liver cirrhosis (LC) and hepatocellular carcinoma (HCC), The plasma alpha 1,3FT activity was significantly higher (p < 0.01) in chronic liver diseases than that in normal controls. The enzyme activity in plasma of patients with HCC was also significantly higher than that in LC (p < 0.05) or that in CH (p < 0.01). However, no significant difference was observed in the enzyme activity between LC and CH. Plasma alpha 1,3FT activity in patients with HCC was not significantly changed before and after transcatheter arterial embolization. In addition, the enzyme activity in the homogenate of the cirrhotic liver tissue was higher than that in the preparation of the hepatoma tissue in the same patient. These results suggest that the increased plasma alpha 1,3FT activity in patients with HCC reflects mainly the enzyme activity of cirrhotic liver tissue, not that of hepatoma tissue. The significance of the elevated levels of plasma alpha 1,3FT and its decreased hepatoma tissue activity in patients with HCC, compared with that in LC, remains to be clarified.

Aged↗
PubMed1995

The high hepatocarcinogen susceptibility of LEC rats is genetically independent of abnormal copper accumulation in the liver.

We previously reported that LEC rats, which show a spontaneous occurrence of liver injury and hepatocellular carcinoma (HCC), are highly susceptible to chemical carcinogens such as diethylnitrosamine (DEN). Since abnormal copper accumulation in the liver of LEC rats was found to be a cause of liver injury, it is necessary to elucidate whether the carcinogen susceptibility of LEC rats is related to the accumulation of copper in the liver. In this study we have examined the relationship between the susceptibility of FI [LEC x LEA or LEC x Fischer 344 (F344)] and FI backcross rats to DEN and hepatic copper concentration, as copper accumulation has been demonstrated to be inherited as an autosomal recessive trait. The groups of F1 and F1 backcross rats were given a single intraperitoneal injection of DEN (20 mg/kg wt) and subjected to a modified Solt-Farber protocol for assaying glutathione S-transferase placental form (GST-P)-positive foci. The hepatic copper concentration was examined by atomic absorption. Although no F1 rats showed a high copper concentration in the liver, the numbers of foci were as high as those in LEC rats which accumulate copper. Backcross rats separated into high and low copper concentration groups at an almost 1:1 ratio, but there was no significant difference in the mean numbers of foci between these two groups. The results clearly indicate that the high susceptibility of LEC rats to DEN is genetically independent of copper accumulation in the liver. A possible dominant inheritance of this high carcinogen susceptibility was suggested. Biochemical measurement of cytochromes P450 and b5 in the liver of F1 rats indicated that alterations in drug metabolizing enzymes may be partially responsible for the high carcinogen susceptibility of LEC rats.

Animals↗
PubMed1995

Mechanism and properties of inhibition of purified rat brain adenylate cyclase by G protein beta gamma-subunits.

The mode of the inhibition of purified rat brain adenylate cyclase by the beta gamma-subunits of G protein (beta gamma) was studied. These subunits inhibited the catalytic activity of the cyclase with the maximal inhibition of 85% and the half-maximal inhibition at about 0.7 nM beta gamma. The complex of beta gamma and adenylate cyclase isolated by density gradient centrifugation contained 1.8-2.0 mol beta gamma per mol of the cyclase when beta gamma was assayed by immunoblotting and by its inhibitory activity on adenylate cyclase. However, the beta gamma concentration-inhibition curves suggest that one of the two beta gamma molecules bound may be essential for the inhibition. The role for the second beta gamma molecule is unknown. As a tentative estimate, 70% of the adenylate cyclase activity remained inhibited by beta gamma when the complex was isolated. The inhibition was not dependent on G alpha s or calmodulin. Although purified adenylate cyclase contained a protein (0.06-0.08 mol/mol of adenylate cyclase) that reacted with anti-G alpha s antibody, this protein was not liberated from the cyclase when it formed a complex with beta gamma. In addition, guanine nucleotide analogs little affected the cyclase activity or the inhibition by beta gamma. The inhibition by beta gamma was reversed by the dilution of the complex, and the following re-addition of beta gamma suppressed the enzyme activity to about 15% of the initial activity again. These findings provide strong evidence that beta gamma inhibits adenylate cyclase directly and reversibly through the formation of the complex.

Adenylyl Cyclases↗
PubMed1995

Effects of ajmaline on non-sodium ionic currents in guinea pig ventricular myocytes.

The lack of currently available data stimulated us to investigate the electrophysiological effects of ajmaline, a classical class Ia antiarrhythmic agent, on various currents responsible for the action potential plateau and repolarization phases. The whole cell patch clamp recording technique was applied to guinea pig ventricular myocytes. Ajmaline suppressed the Ca2+ current (Ica) in a dose-dependent manner (Kd = 1.2 x 10(-5) M) without affecting the steady-state inactivation kinetics and the voltage dependency of the current-voltage relationship. Ajmaline inhibited the inward portion of the inward rectifying K+ current (IKl). Ajmaline decreased the delayed rectifier K+ current (IK) without altering the activation or deactivation time courses. All these inhibitory effects of ajmaline prolonged the action potential duration in a dose dependent manner. The inhibitory actions of ajmaline on the action potential upstroke and various currents responsible for the plateau and repolarization may contribute to the observed suppression of depolarization-induced abnormal automaticities by this agent.

Action Potentials↗
PubMed1995

Effects of inhibitors of ouabain-sensitive Na+, K(+)-ATPase and Li+ ions on the neuromuscular transmission of the frog.

The effect of blockade of ouabain-sensitive alpha 2 and alpha 3 (neural type) isozymes of Na+, K(+)-ATPase was investigated on frog neuromuscular preparations by recording the frequency augmentation-potentiation (FAP) of the endplate potential, an electrophysiological and neuropharmacological technique to analyze the drug actions on the release process of the readily releasable transmitter quanta. Erythrosin B, which was thought to selectively inhibit the neural type Na+, K(+)-ATPase, pivoted the log-linear FAP relation counterclockwise without altering the intercept on the ordinate. Chlormadinone had a similar action. An increase in the concentration of extracellular K+ ions pivoted the FAP relation clockwise with a concomitant upward shift of the intercept on the ordinate, and low K+ Ringer's solution produced an inverse effect. In contrast, Li+ ions shifted the FAP relation upwards dose-dependently leaving its slope unchanged. Cinnarizine, a blocker for inositol-1,4,5-trisphosphate-induced Ca2+ release, and 5,5'-dimethyl-1,2-bis(2-amino-phenoxy)ethane-N,N,N',N'-tetraacetic acid, a specific intracellular Ca2+ chelator, significantly antagonized the potentiating action of Li+. The ouabain-sensitive neural type Na+, K(+)-ATPase isozyme, which is abundant in neural tissues, seems to play an important role in stimulation frequency-dependent modulation of the quantal transmitter release such as FAP.

Adrenal Cortex Hormones↗
PubMed1995

Chemical modification by maleimide of toxic and nontoxic ouabain actions on neuromuscular transmission in the frog.

A dual action of ouabain on the Mg(2+)-blocked frog neuromuscular transmission was studied in two different experimental procedures by measuring the mean quantal content (m) of endplate potentials evoked during repetitive nerve stimulation. The nontoxic action of low-dose (1 microM) ouabain was observed as a counterclockwise pivoting of the linear stimulation frequency versus the log m relation, termed frequency augmentation-potentiation (FAP), whereas the toxic effect of higher doses (> or = 10 microM) of ouabain was recorded as a slow exponential increase in m. Since neural Na+,K(+)-ATPase consists of two or three isoforms, the nontoxic action of low-dose ouabain was anticipated to be a consequence of the selective inhibition of ouabain-sensitive alpha(+) (alpha 2 and alpha 3 or neural type) Na+,K(+)-ATPase activity. Such a possibility was assessed by applying epsilon-maleimidocaproic acid (MCA), a membrane-impermeant sulfhydryl reagent. MCA 15 microM was found in the present study to suppress the nontoxic effect of ouabain without altering the toxic effect. The results strongly suggest that the toxic and nontoxic actions of ouabain are the result of actions on different entities. The ouabain-sensitive neural type Na+,K(+)-ATPase, which is abundant in neural tissues, seems to play an important role in modulation of transmitter release observable as FAP.

Animals↗
PubMed1995

Toxic and nontoxic effects of ouabain on the transmitter release from frog motor nerve terminals.

Toxic and nontoxic effects of ouabain were investigated on frog neuromuscular preparation by measuring the mean quantal content of endplate potentials elicited during repetitive nerve stimulation. In the untreated normal muscles, application of 10 microM ouabain gave rise to a slow exponential increase in the transmitter release (toxic ouabain effect) with a certain delay. This delay was increased with either 100 microM amiloride, a Na(+)-Ca2+ exchange blocker, or the intracellular loading of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), a specific intracellular Ca2+ chelator. Measurements of frequency augmentation-potentiation (FAP) revealed a specific nontoxic effect of ouabain: 1 microM ouabain pivoted the long-linear FAP relation counter-clockwise without altering the intercept on the ordinate. Contrary to their action in the toxic effect, both 100 microM amiloride and the intracellular loading of BAPTA failed to counteract the nontoxic effect of 1 microM ouabain. The present results suggest that the toxic and nontoxic effects of ouabain are of different entities. The ouabain-sensitive subtype of Na+,K(+)-ATPase, which is abundant in neural tissues, seems to play a specific role in the process of nontoxic potentiation of transmitter release.

Amiloride↗
PubMed1995

[Effects of the nitric oxide donor SIN-1 on the membrane potential of mouse neuroblastoma-rat glioma hybrid cells].

The effect of the nitric oxide donor SIN-1 on the membrane potential of cultured mouse neuroblastoma-rat glioma hybrid NG108-15 cells was investigated using the whole cell patch method. It has been reported that neurite formation can be induced in NG108-15 cells by adding of dibutyryl cyclic AMP to the culture medium. Using this system we found that SIN-1 has a selective inhibitory effect on the membrane potential of the calcium current which is concentration-dependent in the 1 mu M-100 microM range. This effect was transient and reversible, the same as seen with the calcium channel blocker nilvadipine at concentrations of 10 microM to 10 microM. At higher concentrations, ranging from 500 microM to 1 mM, however, SIN-1 also caused prolonged inhibition of the membrane potential of the sodium current. However, this effect was also reversible. These findings suggest that SIN-1 has a reversible inhibitory action on the membrane potentials of neurons.

Animals↗