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H Takasaki

Publications and source records attributed to H Takasaki.

At least 19 recordsLinked to original sources
PubMed1999

Recognition of target DNA and transcription activation by the CO-sensing transcriptional activator CooA.

CooA from Rhodospirillum rubrum is a heme-based CO-sensing transcriptional activator, in which CO acts as a physiological effector. In this study, we examined the mechanism of site-specific recognition and transcriptional activation by CooA by elucidating the transcriptional activator activity of the mutant CooA proteins and the chimeric proteins derived from CRP and CooA and the promoter activity of the mutant promoters. Site-directed mutagenesis has revealed that Arg(177), Gln(178), and Ser(181) on the recognition helix of the helix-turn-helix motif in CooA are responsible for the site-specific recognition. The side chains of these amino acid residues at positions 177, 178, and 181 are believed to be hydrogen bonding to the G:A, T:A, and C:G pairs at positions 2/15, 3/14, and 4/13 in the CooA-dependent promoters to recognize the DNA site for CooA. The properties of the CRP/CooA chimeric proteins constructed in this work suggest that CooA activates transcription by a similar mechanism to that of CRP at Class II CRP-dependent promoters.

Amino Acid Sequence↗
PubMed1997

Single transduction in the transcriptional activator CooA containing a heme-based CO sensor: isolation of a dominant positive mutant which is active as the transcriptional activator even in the absence of CO.

We constructed an in vivo reporter system to measure the activity of CooA as the transcriptional activator and showed that the recombinant CooA was active as the transcriptional activator in the presence of CO even in E. coli cells. A dominant positive mutant of CooA, in which Met131 was replaced by Leu, was isolated by a random mutagenesis with this reporter system. The electronic absorption spectra of M131L mutant were identical to those of wild type CooA in oxidized (Fe3+), reduced (Fe2+), and CO-bound (CO-Fe2+) state, indicating that the coordination structure and environment of the heme were not changed by this mutation. Methionine at position 131 was the carboxyl-terminal end of the heme-binding domain of CooA, which would be adjacent to the hinge region connecting the heme-binding domain and the DNA-binding domain.

Bacterial Proteins↗
PubMed1995

[A case of pulmonary blastoma composed of histological features of both pulmonary blastoma and pulmonary endodermal tumor resembling fetal lung].

A case of pulmonary blastoma in a 71-year-old male was reported. Chest X-ray and CT scan showed a well demarcated mass lesion in the apical segment of the right lung. A polypoid tumor was detected in the apical branch of the right bronchus by bronchoscopy. The biopsy confirmed the diagnosis of pulmonary blastoma. The patient underwent a right upper lobectomy with lymph nodes dissection on Jan. 26, 1990. The resected tumor was really composed of two parts: a main tumor in the lung parenchyma and polypoid one protruding into the bronchus from the main tumor. The polypoid tumor exhibited typical features of pulmonary blastoma with both carcinomatous and sarcomatous components. The histology of the main tumor was identical to pulmonary endodermal tumor resembling fetal lung (PET). The metastases in the excised lymph nodes consisted entirely of carcinomatous elements. The patient died of brain stem metastasis a year after his operation. The present case, with typical pulmonary blastoma and PET present in the same tumor, supports the idea that pulmonary blastoma and PET belong to the same group neoplasma.

Aged↗
PubMed1994

Polymannosylation to asparagine-19 in hen egg white lysozyme in yeast.

Complementary DNA encoding hen egg white lysozyme (HEWL) was subjected to site-directed mutagenesis to have the N-glycosylation signal sequence (Asn19-Tyr20-Thr21) by substituting Arg with Thr at position 21. The mutant lysozyme (R21T) was expressed in Saccharomyces cerevisiae carrying the yeast expression plasmid inserting the mutant HEWL cDNA. The mutant lysozyme was expressed in the glycosylated forms which are mainly a polymannosyl form with a small amount of oligomannosyl form. The polymannosyl lysozyme was susceptible to Endo H cleavage of the carbohydrate chain. The length of the polymannose chain was predicted to be approximately 340 residues/mol of lysozyme from carbohydrate analysis. According to the estimation with low-angle laser light scattering combined with HPLC, the average molecular weight of polymannosyl lysozyme was 75 kDa, which is consistent with the value obtained from the carbohydrate analysis. The size of polymannosyl lysozyme R21T is similar or somewhat larger than that of G49N reported previously. Thus, it was confirmed that the unusually large polymannose chain was attached to heterologous mutant lysozyme, regardless of the N-linked position, in yeast.

Acetylglucosamine↗
PubMed1994

Biocompatibility of a heparin-bonded membrane oxygenator (Carmeda MAXIMA) during the first 90 minutes of cardiopulmonary bypass: clinical comparison with the conventional system.

We clinically compared a heparin-bonded Carmeda MAXIMA membrane oxygenator to a nonheparin-bonded MAXIMA in 20 patients undergoing coronary artery bypass grafting or valve replacement. Reductions of fibrinogen, factor XII, and high molecular weight kininogen were greater in the MAXIMA group. Serum C3a and free hemoglobin were lower in the Carmeda group. The level of C4a, though remarkably lower than that of C3a, was higher in the Carmeda group then in the MAXIMA group. Both oxygenators performed well in terms of blood gas exchange. We conclude that the heparin-bonded Carmeda oxygenator offers superior biocompatibility during cardiopulmonary bypass.

Biocompatible Materials↗
PubMed1994

[Two cases of aortoesophageal fistula due to ruptured thoracic aortic aneurysm].

Aortoesophageal fistula due to ruptured thoracic aortic aneurysm is uncommon, and exhibits extremely high mortality. We experienced two cases of such lesion. The first case showed aneurysm in the aortic arch closed with Dacron patch but leaving the esophageal defect. The patient died of an infection of the patch graft after oral feeding. The second case was demonstrated infected aneurysm of the descending aorta. The patient was rescued by primary operation, replacement of the aorta by an artificial graft and resection of the esophagus, and the secondary operation, reconstruction of the esophagus. We recommend resection of aneurysm and the esophagus as well in the aspect of lower post-operative infection in the graft and of the better prognosis of the lesion.

Aged↗
PubMed1993

Hyperglycosylation of hen egg white lysozyme in yeast.

The large molecular size of N-glycosylated lysozyme with a polymannose chain was predominantly expressed in the yeast carrying the lysozyme expression plasmid in 9-fold greater secretion compared with the wild type. Complementary DNA encoding hen egg white lysozyme was subjected to site-directed mutagenesis to obtain the Asn-X-Ser/Thr sequence that is the signal for asparagine-linked (N-linked) glycosylation. At positions 49, 67, 70, and 103, the signal for N-linked glycosylation was created. Only the mutant lysozyme whose glycine 49 was substituted with asparagine was expressed in the two types of glycosylated forms, a small oligomannose chain (Man18GlcNAc2)-linked form and a large polymannose chain (Man310GlcNAc2)-linked form, whereas other mutants were not glycosylated. The secreted amount of polymannosyl lysozyme was much higher than that of the oligomannosyl lysozyme. Both types of glycosylated lysozymes were susceptible to endo-beta-N-acetylglucosaminidase cleavage of their carbohydrate chains. The average molecular masses of oligomannosyl and polymannosyl lysozymes were 18 and 71 kDa, respectively. The length of the polymannose chain was found to be 200-350 residues/molecule of lysozyme according to the estimation of the molecular mass distribution by low angle laser light scattering measurements. The protein conformation estimated by CD analysis was completely conserved in these glycosylated lysozymes. The enzymatic activities of oligomannosyl and polymannosyl lysozymes were 100 and 91%, respectively, of wild-type protein when glycol chitin was used as a substrate. In addition, the polymannosyl lysozyme revealed remarkable heat stability in that no coagulation was observed under conditions in which the wild-type lysozyme coagulated. Thus, this novel glycoprotein can be used as a reporter in studies of the processing and sorting of glycoproteins and as a model of the expression of foreign genes in yeast for the construction of stable enzymes.

Animals↗
PubMed1993

[Clinical experience of VA-bypass as a cardiac assist system using centrifugal pump with membranous oxygenator in patients with profound ventricular failure after cardiac surgery].

Twelve patients including 6 ischemic heart diseases, 5 valvular diseases, and one adult atrial septal defect combined with mitral and tricuspid valve insufficiency were treated with circulatory assist system for postoperative severe low-cardiac output syndrome. Intra-aortic balloon pumping (IABP) was used in all cases. In early 7 cases, left heart bypass system was employed including one roller pump, one left ventricular assist device (LVAD), and 5 centrifugal pump. Only one LVAD case could be weaned but died of sustained ventricular arrhythmias 5 days postoperatively. In recent 5 cases, veno-arterial bypass (VA-bypass) was employed using centrifugal pump with membranous oxygenator. Venous blood was drained from the right atrium and oxygenated blood was returned to the right axillary artery. Real time reinfusion of drained blood from intrapericardial and mediastinal tube to the central vein served efficiently to maintain hemodynamics and to save homologous blood transfusion. Three of 5 cases who were treated with Va-bypass survived and are doing well. We conclude that VA-bypass consisting with centrifugal pump and oxygenator returning oxygenated blood to the right axillary artery combined with IABP were useful strategies as biventricular support for profound cardiac failure following surgery.

Aged↗
PubMed1993

[Surgical treatment of endocardial cushion defect in 3 elderly patients].

We performed surgical treatment for partial endocardial cushion defect in 3 patients over fifty year old. Case 1 was a 55-year-old-male with TR of grade II. Case 2 was a 59-year-old-female with TR and MR, and was repaired mitral cleft by a mattress suture. She needed infusion of dopamine (over 5 micrograms/kg/min) for 6 days and therapy of mediastinitis postoperatively. Case 3 was 56-year-old-male without atrioventricular valve regurgitation. Preoperative left ventricular volume was small in all patients, therefore perioperative circulatory control, mainly water balance, and respiratory control were importance. All patients survived, and both decreasing of CTR and improvement of NYHA classification were recognized in all three patients. In conclusion the operation for ECD in even elder patients was effective, but intensive care needed perioperatively.

Endocardial Cushion Defects↗
PubMed1993

[A case of double mitral valve with severe mitral regurgitation detected by transesophageal echocardiography].

A 66-year-old woman with double mitral valve (bridge type) and severe mitral regurgitation by spontaneous ruptured chordas is reported. The case with this combination has not been reported in the literature. She had not any other congenital heart diseases. The mitral valve was clearly shown by two-dimensional Doppler transesophageal echocardiography. Mitral valve replacement with Medtronic-Hall valve was carried out successfully.

Aged↗
PubMed1993

[A case of aortic dissection (DeBakey-I) occurring 20 months after aortic valve replacement].

Simple aortic valve replacement was performed in a 59-year-old man whose ascending aorta was moderately dilated (45 mm) because he had no characteristics of Marfan's syndrome or other connective tissue diseases. However, about 20 months later, reoperation needed to be performed for aortic dissection of DeBakey type I. The pathological findings of the aortic wall obtained at the initial operation revealed cystic medial necrosis. The occurrence of aortic dissection after aortic valve replacement is uncommon but not rare, especially in patients with cystic medial necrosis and/or dilated aortic root. Therefore, in these patients, wrapping or replacement of the ascending aorta may be required at the same time of aortic valve replacement.

Aortic Dissection↗
PubMed1992

Myocardial damage caused by free radicals in experimentally induced myonephropathic metabolic syndrome in dogs.

Myocardial damage was studied in the dog heart with experimentally induced myonephropathic metabolic syndrome (MNMS). The animals underwent a ligation of the infrarenal arteries with a re-establishment of arterial flow 5 hours after the operation (group 1) and all showed the typical phenomena of MNMS and revealed basophilic changes in the myocardial cells fixed with 4 per cent formalin in 2 per cent calcium acetate. These degenerated cells were distributed in either the left or right ventricle, or even in both as several foci composed of a considerable number of the myocardial cells. Most of these cells showed a significantly enhanced expression of immunoreactive copper-zinc superoxide dismutase in their sarcoplasm. With luxol fast blue staining, the basophilic myocardial cells appeared to be deep blue in color which indicated an accumulation of phospholipid. Such basophilic cells in the animals undergoing a sham operation (group 2) were only sporadically observed in the myocardium fixed with the same fixative. The present study including morphological procedures indicates that dog MNMS causes severe myocardial damage with superoxidation due to an excessive production of free radicals after the re-establishment of arterial flow.

Animals↗
PubMed1992

Determination of urinary 18-hydroxycortisol in the diagnosis of primary aldosteronism.

Urinary excretion of 18-hydroxycortisol (18-OHF), 18-hydroxycorticosterone (18-OHB) and aldosterone 18-glucuronide (Aldo-18-glu) was measured in 10 patients with primary aldosteronism; 5 with aldosterone-producing adenoma (APA) and 5 with idiopathic hyperaldosteronism (IHA), 10 patients with essential hypertension (EHT) and 11 normotensive subjects. In EHT patients, urinary 18-OHF (172 +/- 15 micrograms/24h) and 18-OHB (3.1 +/- 0.6 micrograms/24h) values were not significantly different from 18-OHF (142 +/- 35 micrograms/24h) and 18-OHB (3.6 +/- 0.5 micrograms/24h) in the controls. Urinary 18-OHF values were significantly higher in APA (640 +/- 213 micrograms/24h) when compared with controls and EHT, whereas 18-OHB (11.3 +/- 1.5 micrograms/24h) values were only slightly elevated. Both 18-OHF and 18-OHB were significantly increased in APA compared with 18-OHF (232 +/- 56 micrograms/24h) and 18-OHB (4.6 +/- 0.3 micrograms/24h) in IHA. The two urinary steroids, especially 18-OHF proved to be a useful marker for the diagnosis of APA, confirming the previous findings. Aldo-18-glu was not significantly different between APA and IHA. In normal subjects when sodium intake was restricted to 48meq/day for four days the urinary 18-OHF was increased two fold to 383 +/- 59 micrograms/24h (p less than 0.01 vs control period) associated with comparable rise in plasma renin activity. This suggests that the biosynthesis of 18-OHF is partly under control of renin-angiotensin axis in normal subjects.

18-Hydroxycorticosterone↗
PubMed1992

[Hemodynamic management of LOS using prolonged VA bypass circulatory assist].

The authors managed five LOS patients using prolonged V-A bypass circulatory assist. Maximum CVP values were under 12 mmHg in three survivors, and 17 mmHg and 20 mmHg in two nonsurvivors. Maximum PCWP values were under 14 mmHg in survivors, and 19 mmHg and 20 mmHg in nonsurvivors. Dopamine was administrated in all cases and norepinephrine was administrated at a rate of less than 0.3 microgram.kg-1.min-1 in survivors, and in two nonsurvivors, norepinephrine was used at a rate of 0.36 and 1.2 micrograms.kg-1.min-1. Before and after disconnection of V-A bypass, the bypass flow of the three survivors were under 1.0 l.min-1 just before disconnection, and immediately after it, the preload did not increase, and the dose of administrated catecholamine increased. V-A bypass time intervals of the three survivors were 71, 42 and 87 hours, and those of the two nonsurvivors were 71 and 43 hours. Maximum bypass flow rate was above 40ml.kg-1.min-1 in four of five patients. The authors discussed the management of the patients' heart and of the V-A bypass machine during the prolonged V-A bypass circulatory assist.

Aged↗