Search PubMed⌕ Search

Biomedical subjects

E Yamaguchi

Publications and source records attributed to E Yamaguchi.

144 records · Page 8Linked to original sources
PubMed1984

Thermophilic DNA ligase. Purification and properties of the enzyme from Thermus thermophilus HB8.

Thermophilic and thermostable DNA ligase was purified to near homogeneity from the extract of Thermus thermophilus HB8. The purified enzyme has an isoelectric point at pH 6.6 and consists of a single polypeptide of about 79,000 in molecular weight on the bases of sodium dodecyl sulfate-polyacrylamide gel electrophoresis data and an equilibrium sedimentation method. The enzyme requires divalent cations, Mg2+ or Mn2+, and the optimum concentration of these ions being 5-9 X 10(-3) M and 3-6 X 10(-3) M, respectively. The enzyme also requires NAD as a cofactor. The apparent Km for NAD is 1.85 X 10(-8) M and that of (dT)10 is 1.4 X 10(-4) M. The pH optimum is 7.4-7.6 in Tris-HCl and 8.0 in collidine/HCl buffer. The joining reaction is activated by K+ and NH+4 at a concentration of 2-100 mM and inhibited by Na+ above 25 mM. The optimum temperatures of the joining of thymidylate oligomers in the presence of poly(dA) as a template are 27.5 degrees C for p(dT)s, 34.5 degrees C for p(dT)10, and 37 degrees C for p(dT)12-18 and that of cohesive-end DNA restriction fragments is 24-37 degrees C. The nick-closing activity of the enzyme was observed over a wide range of the temperature from 15 to 85 degrees C and the optimum temperature is 65-72 degrees C. The temperature dependency of ligation with HB8 DNA ligase for various substrates was found to shift to a region of 7-10 degrees C higher than that of T4 DNA ligase and the activity of HB8 DNA ligase decreased remarkably below 4 degrees C. The enzyme was stable for 1 week at 37 degrees C, its activity dropped by 50% within 2 days at 65 degrees C.

Cations, Divalent↗
PubMed1982

Relationship between the Ba-induced contraction and cyclic AMP levels in the isolated longitudinal smooth muscle from guinea pig ileum.

Relationship between contraction and cyclic AMP levels induced by BaCl2 was examined in the longitudinal smooth muscle isolated from guinea pig ileum. BaCl2 3 X 10(-3)M caused a fast initial contraction, often followed by a gradual decrease of the contractile state. There was an increase in the tissue cyclic AMP 7 min or 14 min after the application of Ba. A phosphodiesterase activator imidazole reinforced the later phase of contraction by Ba and inhibited the increase in cyclic AMP. These results indicate that there is still a positive correlation between relaxation and increase in cyclic AMP and that an inhibitory action mediated by cyclic AMP is veiled behind the Ba contraction. Furthermore, these results may be interpreted by assuming that strong Ba contraction operates a feedback mechanism and that the feedback mechanism is associated with cyclic AMP increase. Indomethacin, an inhibitor of prostaglandins synthesis, little influenced the Ba-induced increase in cyclic AMP and rather inhibited the Ba contraction. Propranolol, a beta-adrenergic blocking agent, failed to exert influence on the Ba contraction. Based on these facts, it is suggested that the increase in cyclic AMP is not mediated by prostaglandins or catecholamines.

Animals↗
PubMed1981

Smooth muscle relaxing drugs and guinea pig ileum.

The effects of various smooth muscle relaxing drugs on contractile responses to acetylcholine (ACh), Ba2+ and Ca2+, and on the tissue cyclic AMP levels were examined in the guinea pig ileum. Papaverine and theophylline caused a decrease both in the maximum height and the slope of dose-response curves induced by the three stimulants, and an increase in the cyclic AMP levels. Diltiazem and D-600 produced a decrease in the maximum and the slope of ACh and Ba2+ dose-response curves, shifted the Ca2+ dose-response curves to higher concentrations, in a parallel manner, but failed to change the cyclic AMP levels. Etomidoline and benactyzine shifted the curves for the three stimulants in parallel to the right, but at higher concentrations depressed the maximum of ACh and Ba2+ responses with a further parallel shift. These drugs exerted little influence on the basal level of tissue cyclic AMP, but etomidoline significantly depressed the Ba2+ -induced increase in cyclic AMP level. The smooth muscle relaxing drugs used could be classified in three types, thereby suggesting that there are at least three different mechanisms involved in smooth muscle relaxing action.

Acetylcholine↗
PubMed1976

Influence of cholinergic drugs on the lateral geniculate phasic waves.

The lateral geniculate phasic wave (GL wave, GLW) was studied at awaking, during the REM period of sleep (REMP) and after administration of reserpine (RSP) and parachlorophenylalanine (PCPA). The GLWs were classified by the time relation to the eye movements (EMs) into three groups of the GL-preceding GLW (GLWs precede EMs or concur with EMs), the EM-preceding GLW (EMs precede GLWs) and the EM-discording GLW (GLWs not associated with EMs). Changes in occurrence of thus classified GLWs and in the EM-GLW time (time delay between EM and GLW) were examined with supplementary administration of eserine and atropine. The results were as follows: 1. During the REMP, the EM-GLW time of the GL-preceding GLW showed shortening by eserine and prolongation by atropine. On the other hand, the EM-GLW time of the EM-preceding GLW was recognized no definite affection. 2. After the administration of RSP and PCPA, the GL-preceding GLWs increased soon after the eserine injection whereas markedly decreased after atropine. In the atropine-pretreated cats, the occurrence of the GL-preceding GLWs by RSP was inhibited. These drugs exerted little influence on the occurrence of the EM-preceding GLWs. 3. These results suggest that cholinergic mechanisms underlie the production of the GL-preceding GLWs but don't play an important role in the production of the EM-preceding GLWs.

Animals↗
PubMedDate not supplied

A case of Walker-Warburg syndrome with uncommon findings. Double cortical layer, temporal cyst and increased serum IgM.

We report a Japanese boy with the Walker-Warburg syndrome. He had typical clinical features, including type II lissencephaly, congenital muscular dystrophy and an ocular abnormality associated with previously undescribed findings, a double cortical layer and an isolated cyst evident on magnetic resonance imaging, and an increased level of serum IgM. We speculate that the inner layer of the cortices in this case represents a layered heterotopia under the cerebral cortex.

Brain Diseases↗
PubMedDate not supplied

Myocardial metastasis from primary lung cancer: myocardial infarction-like ECG changes and pathologic findings.

Myocardial metastasis from neoplastic disease is often clinically unapparent, and very difficult to diagnose. Of 151 consecutive autopsies of lung cancer patients, cardiac metastases were found in 67 patients (44.4%). Myocardial metastasis was found in only 8 patients (11.9%). ECG of patients with myocardial metastasis revealed ST-T wave changes and various types of arrhythmia. ST-T wave changes were observed in 4 with myocardial metastasis, and in 6 without myocardial metastasis (pericardial metastasis alone). ST-T wave changes is not a specific finding of myocardial metastasis. Two very rare cases with myocardial metastasis showing progressive ST segment elevation with a QS pattern are presented. The appearance of ST segment elevation with a QS pattern in clinically stable lung cancer patients without cardiac symptoms suggestive of myocardial injury indicates the possibility of myocardial metastasis. Myocardial metastasis is often elusive, thus careful observation of ECG changes is of primary importance for the antemortem diagnosis.

Adenocarcinoma↗