Biomedical subjects

H Masaki

Publications and source records attributed to H Masaki.

At least 217 records · Page 12Linked to original sources

PubMed1992

Identification of a 27-kilodalton protein with the properties of type I iodothyronine 5'-deiodinase in human thyroid gland.

N-Bromoacetyl-[125I]T4(BrAc[125I]T4) was used as affinity label to identify type I 5'-deiodinase (5'-D) in human thyroid glands. Affinity labeled proteins were analyzed by autoradiography after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Human thyroid microsomes labeled with BrAc[125I]T4 showed the most prominent radiolabeled band of protein at a mol wt of approximately 27,000 (p27). BrAc[125I]T4 incorporations into p27 were significantly higher in both Graves' and follicular adenomas than in normal thyroids. On the other hand, four cases out of five carcinomas were lower than the least value of normal thyroids. Furthermore, an excellent correlation was observed between 5'-D activities and quantities of p27 in all cases (r = 0.96; P less than 0.001). Labeling of p27 was strongly inhibited by preferred type I 5'-D substrate rT3, but to a lesser extent by poor substrate T4 or T3, and the type I 5'-D inhibitor, propylthiouracil and iopanoic acid, also inhibited the p27 labeling in normal and various diseases. In addition, the rate of enzyme inactivation by BrAcT4 equaled the rate of p27 labeling. These data suggest that p27 may be a type I 5'-D itself or at These data suggest that p27 may be a type I 5'-D itself or at least the substrate-binding subunit of this enzyme in human thyroid, and that both Graves' and follicular adenoma thyroids contain larger amounts of it, and papillary adenocarcinoma thyroids smaller than normal amounts.

Adenocarcinoma, Papillary↗

PubMed1992

3,3',5'-Triiodothyronine inhibits collagen-induced human platelet aggregation.

To clarify further the activity of rT3, we examined the effect of rT3 on collagen-induced platelet activation as reflected by aggregation, serotonin release, and protein phosphorylation. rT3, T4, T3, and triiodothyroacetic acid inhibited collagen-induced platelet aggregation and serotonin release from platelets in a dose-dependent manner. However, thyronine did not inhibit collagen-induced platelet aggregation. The concentration at which rT3 inhibited by 50% collagen-induced platelet aggregation was 30 +/- 4 (mean +/- SE) mumol/L. rT3, T4, and T3 did not differ significantly in their abilities to inhibit platelet aggregation. Moreover, rT3 inhibited collagen-induced phosphorylation of the 20-kilodalton protein (myosin light chain) in platelets. In contrast, rT3 did not inhibit 12-O-tetradecanoylphorbol 13-acetate (TPA)- or thrombin-induced platelet aggregation and inhibited only minimally TPA-induced 40-kilodalton protein phosphorylation. These results suggest that rT3 inhibits collagen-induced platelet activation by inhibiting the activity of myosin light chain kinase and that it may be interesting to investigate some kinds of activity of rT3.

Blood Platelets↗

PubMed1992

Coronary ostial endarterectomy in Takayasu's aortitis--confirmation of patency nine years postsurgically.

A case of Takayasu's aortitis with severe bilateral coronary ostial stenosis is reported. A transaortic coronary endarterectomy was performed and sufficient patency was confirmed angiographically 9 years after the operation. This is the first report of late coronary angiography after a transaortic coronary ostial endarterectomy in Takayasu's aortitis. The efficacy of this procedure for coronary ostial stenosis in Takayasu's aortitis is emphasized.

Adolescent↗

PubMed1992

[The assessment of clinical usefulness of 131I-MIBG scintigraphy for localization of tumors of sympathetic and adrenomedullary origin--a report of multicenter phase III clinical trials].

A phase III clinical study of 131I-metaiodobenzylguanidine (131I-MIBG) was performed in 66 patients with tumors of sympathetic and adrenomedullary origin, including 32 patients with suspected pheochromocytoma, 25 with suspected neuroblastoma, 7 pre- or postoperative medullary carcinoma of the thyroid and each with carcinoid and suspected Sipple's syndrome. A total of 150 sites which were confirmed for presence (72 sites) or absence (78 sites) of tumors were examined on 131I-MIBG scintigrams. True positive ratio of the scintigraphy was 84.7% (61/72) and true negative ratio was 94.9% (74/78). Positive scintigraphy was obtained in 86.5% (32/37) of pheochromocytoma, 78.6% (22/28) of neuroblastoma and 100% (6/6) of medullary carcinoma of the thyroid. Accumulation of 131I-MIBG was seen in 16.8% of normal adrenal glands. Neither adverse reactions nor abnormal laboratory findings were noted in relation to 131I-MIBG injections. Our study indicates that 131I-MIBG is a safe and clinically useful radiotracers for the visualization and localization of tumors of sympathetic and adrenomedullary origin.

3-Iodobenzylguanidine↗

PubMed1992

[Overt leukemia from MDS associated with marked basophilia].

A 52-year-old woman was admitted to our hospital because of leukocytosis. She had been diagnosed with RAEB in another hospital in past time. At the admission, the white cell count was 30,900/microliter with blasts (14.0%) and marked basophilia (49.0%). Bone marrow aspiration revealed with 30.2% blasts and 21.1% basophils. Having obtained those results, diagnosis of RAEB in transformation was made. After admission, number of basophils in peripheral blood increased gradually, and level of histamine in serum was elevated significantly. Multiple peptic ulcers in stomach and bowel and high fever were induced due to histaminemia. Despite several therapy she died because of respiratory failure and septisemia. Although the mechanism of basophilia in this patient could not be clarified, there was a possibility that basophilia in this patient might be differentiated from leukemic clone because almost basophils in peripheral blood were mature and those had many granules including metachromasia by stained with toluidine blue.

Basophils↗

PubMed1992

[Choice of conduit in coronary bypass surgery].

Since 1987, arterial conduits have been used in 78 of 130 cases receiving coronary bypass surgery, including 25 treated by arterial conduits alone. The use of arterial conduits was mainly indicated to the anterior descending coronary artery (LAD), but the saphenous vein had to be used in 39 percent, 47 of 120 cases receiving bypass grafting to the LAD for various reasons including a combination of multiple obstructive arteriosclerosis, multiple bypass graftings in the aged, unstable angina, emergency operation and no suitable artery for a conduit as indicated by preoperative angiography. Hereafter, arterial conduits for coronary bypass grafting to LAD should be used in many more cases to the best possible advantage.

Adult↗

PubMed1992

[The influence of increase in heart rate on coronary flow dynamics in the patients with aortic stenosis].

To clarify the causative factors responsible for the development of effort angina in aortic stenosis, the influence of an increase in heart rate by atrial pacing and isoproterenol infusion on the phasic left coronary flow velocity waveforms were studied using a pulsed Doppler velocimeter during cardiac surgery. Coronary flow velocity waveforms in aortic stenosis was characterized by a slowly increased diastolic inflow and an elongation of the time from the onset of diastole to the diastolic peak velocity. An increase in heart rate by pacing brought about a marked decrease in diastolic coronary flow since the slowly increasing diastolic flow was cut with the onset of following systole. On the contrary, after an increase in heart rate by infusion of isoproterenol, diastolic increasing rate in the coronary flow waveform accelerated and diastolic peak velocity markedly increased. As the results, isoproterenol produced a significant increase in diastolic coronary inflow.

Aged↗

PubMed1992

[Four cases of aortic valve replacement in aortitis syndrome].

Four surgically treated cases of aortic valve regurgitation associated with the aortitis syndrome were reported. All patients were female and ranged in age from 38 to 51 years. In two cases, obstructive lesions of the aortic arch branch were seen in aortograms. Three patients had no inflammatory findings at the operation and one was operated on after improvement of inflammatory findings by steroid therapy. Aortic regurgitation was caused by annuloaortic ectasia, and aortic valve replacement was performed by the everting mattress suture method in all cases. One patient with stenosis of the left carotid artery, occlusion of the left subclavian artery, and hypertension died of extended cerebral damage due to suspected low flow cerebral perfusion during cardiopulmonary bypass. The other three patients are doing well 4 months to 11 years after surgery without paravalvular leakage. In cardiac surgery for the aortitis syndrome with an obstructive lesion of the aortic arch branch, deep hypothermic and high flow cardiopulmonary perfusion is required to prevent ischemic brain complications during surgery.

Adult↗

PubMed1991

Identification of a unique specificity determinant of the colicin E3 immunity protein.

Plasmid immunity to a nuclease-type colicin is defined by the specific binding of an immunity (or inhibitor) protein, Imm, to the C-terminal nuclease domain, T2A, of the colicin molecule. Whereas most regions of colicin operons exhibit extensive sequence identity, the small plasmid region encoding T2A and Imm is exceptionally varied. Since immunity is essential for the survival of the potentially lethal colicin plasmid (Col), we inferred that T2A and Imm must have co-evolved, retaining their mutual binding specificities. To evaluate this co-evolution model for the col and imm genes of ColE3 and ColE6, we attempted to obtain a stabilized clone from a plasmid which had been destabilized with a non-cognate immunity gene. A hybrid Col, in which the immE3 gene of the ColE3 was replaced with immE6 from ColE6, was lethal to the host cells upon SOS induction. From among this suicidal cell population, we isolated a stabilized, i.e., evolved, clone which produced colicin E3 (E3) stably and exhibited immunity to E3. This change arose from only a single mutation in ImmE6, from Trp48 to Cys, the same residue as in the ImmE3 sequence. In addition, we constructed a series of chimeric genes through homologous recombination between immE3 and immE6. Characterization of these chimeric immunity genes confirmed the above finding that colicins E3 and E6 are mostly distinguished by only Cys48 of the ImmE3 protein.

Amino Acid Sequence↗

PubMed1991

Construction and characterization of the chimeric enzymes between the Bacillus subtilis cellulase and an alkalophilic Bacillus cellulase.

The amino acid sequences of cellulase from Bacillus subtilis (BSC) and that from an alkalophilic Bacillus sp. N-4 (NK1) show significant homology in most parts except for the C-terminal portions. Despite the high homology, the pH activity profiles of the two enzymes are quite different; BSC has its optimum pH at 6-6.5, whereas NK1 is active over a broad pH range from 6 to 10.5. In order to identify the structural features which determine such pH activity profiles, chimeric cellulases between BSC and NK1 were constructed using four restriction sites commonly present within the homologous coding sequences, and were produced in Escherichia coli. The chimeric cellulases showed various chromatographic behaviors, reflecting the origins of their C-terminal regions. The pH activity profiles of the chimeric enzymes in the alkaline range could be classified into either the BSC or NK1 type mainly depending on the origins of the fifth C-terminal regions. In the acidic range, the profile was determined only by the origin of the fourth enzyme region from the N terminus. Comparison of the kinetic parameters between pH 5 and 6 using p-nitrophenyl cellobioside as a substrate indicated that the fourth region is responsible for the pH-dependent change of the kcat value. Only a limited number of amino acids in the fourth region may affect on deprotonation of catalytic residues of the cellulases and modulate the catalytic activity in the acidic pH values.

Amino Acid Sequence↗

PubMed1991

Cloning and sequencing of a cyclodextrin glucanotransferase gene from Bacillus ohbensis and its expression in Escherichia coli.

A cyclodextrin glucanotransferase (CGTase) gene of Bacillus ohbensis was cloned in Escherichia coli and the nucleotide sequence was determined. A single open reading frame (2112 bp) with a TTG codon as an initiator was identified that encodes a typical signal peptide of 29 amino acids followed by the mature enzyme (675 amino acids), of which the partial amino acid sequences of the N-terminal region and some lysyl-endopeptidase fragments were determined by Edman degradation. The CGTase gene was expressed in E. coli under control of the lac promoter only when the upstream region containing a long inverted repeat structure (located at -108 to -67 bp from the initiation codon) was deleted. Substitution of an ATG codon for the initiation TTG triplet doubled the expression of the CGTase gene in E. coli. Enzyme preparations purified from the culture supernatant of B. ohbensis and from the periplasmic fraction of the E. coli transformant exhibited the same molecular weight (Mr) and enzymatic properties as follows: Mr, 80,000; optimum pH for activity, 5.0 (and a suboptimum at 10.0); stability between pH 6.5 and 10.0; optimum temperature for activity, 55 degrees C; and stability below 45 degrees C. The yields of the products from starch as the substrate were 25% for beta- and 5% for gamma-cyclodextrin.

Amino Acid Sequence↗

PubMed1991

Induction of anti-idiotypic T cells through a network mechanism.

BALB/c mouse T cells that recognized the idiotype expressed on M104E(mu, lambda 1) were induced by immunization with Dextran B-1355. T cells derived from mice immunized with 1 mg of Dextran B-1355 showed a marked proliferative response against M104E, whereas T cells from mice immunized with Ficoll or smaller amounts of Dextran B-1355 did not. BCL1Id, which had an identical isotype, did not induce proliferation of T cells. The T cell proliferative response against the idiotype on M104E required macrophages as antigen-presenting cells. The proliferative response was inhibited when antigen-presenting cells were treated with NH4Cl or chloroquine, which are antigen-processing inhibitors. These results indicate that anti-idiotypic T cells which recognized processed idiotopes could be induced physiologically through a network mechanism.

Animals↗

PubMed1991

Arginine vasopressin attenuates phenylephrine-induced forearm vasoconstriction in men.

1. The aim of this study was to examine whether arginine vasopressin modulates the vasoconstricting action of phenylephrine in human forearms. 2. In seven healthy subjects, we determined the percentage increases in forearm vascular resistance evoked by intra-arterial infusion of phenylephrine at graded doses during simultaneous intra-arterial infusion of saline or arginine vasopressin at two doses. Similarly, in another seven subjects, we examined the effects of intra-arterial infusions of saline or angiotensin II on the vasoconstricting action of intra-arterial phenylephrine. 3. Arginine vasopressin and angiotensin II caused small, but insignificant, increases in baseline forearm vascular resistance. Arginine vasopressin at the two doses significantly attenuated the percentage increases in forearm vascular resistance evoked with phenylephrine at graded doses. Angiotensin II did not alter the forearm vascular responses to phenylephrine. 4. Intra-arterial infusion of arginine vasopressin at doses of 0.6 and 1.8 ng/min raised the plasma arginine vasopressin concentration in the venous effluents from 1.6 +/- 0.3 (control) to 4.0 +/- 0.9 and to 16.4 +/- 6.9 pg/ml, respectively. 5. These results suggest that arginine vasopressin at physiological concentrations with a minimal direct effect on resistance arteries attenuates the vasoconstricting action of phenylephrine in human forearms.

Adolescent↗

PubMed1991

[Hafnia alvei septicemia with shock and DIC in an adult with postoperative lung cancer].

In Japan, we experienced the first case of Hafnia alvei septicemia with shock and disseminated intravascular coagulation (DIC) in an adult with postoperative lung cancer. A 63 year-old male, who had been followed up in our department since 1987, was admitted to our hospital with the complaints of fever, hemoptysis and dyspnea on June 25, 1989. After admission, he was treated with sulbactam/cefoperazone 4 g/day intravenously for suspicion of respiratory-tract infection. After antibiotic administration, the fever subsided and the general condition became almost good. The patient experienced fever again after the antibiotic was stopped. For this reason subsequent Clavulanic acid/Amoxicillin, Flomoxef, and Ceftazidime was administered, but was not effective. Therefore septicemia was suspected and blood culture was done. The bacteria isolated from blood culture was identified as Hafnia alvei. Hafnia alvei is a gram-negative organism belonging to the Enterobacteriaceae family and quite rare pathogen in human.

Bacteremia↗

PubMed1991

[A case of Enterococcus faecalis brain abscess in a patient with suprapharyngeal cancer].

A 55-year-old male was admitted to our hospital for the treatment of suspected brain abscess on March 18, 1989. The brain CT scan showed low density area with ring enhancement. After admission, both cefminox 2 g/day and clindamycin 500 mg/day were administered intravenously. On March 29, 1989, the patient developed cerebral herniation suddenly. Therefore emergency burr hole operation was done. Many gram-positive cocci were observed on gram-staining of the aspirated pus. Moreover neutrophils with phagocytosed gram-positive cocci were also observed. Culture of aspirated pus revealed colonies of gram-positive cocci which were subsequently identified as E. faecalis. Same species of bacteria were also isolated from fistula of right mastoid. From both findings of brain CT scan and data of MICs of E. faecalis, it may be suggested that direct infection developed from right mastoiditis to intracranial space. We experienced a severe case who developed cerebral herniation because of brain abscess due to E. faecalis which is an infrequent pathogen of brain abscess.

Brain Abscess↗

PubMed1991

Maximum venous outflow and development of deep vein thrombosis.

To evaluate the relationship between maximum venous outflow (MVO) of the leg and development of deep vein thrombosis (DVT), venous occlusion plethysmography (VOP) using a Mercury strain gauge was carried out in 56 unilateral DVT patients. The data from these patients were compared with those obtained from several control groups. Then, the relationship between plethysmographic and 9 clinical variables was statistically analysed in the normal legs of these patients. The mean MVO of the normal legs of these patients was significantly higher than that of the affected legs, but it was significantly lower than those of normal controls and patients with mild congestive heart disease. However, it was similar to those in patients with lymphedema and obese men. A decrease in the MVO of the normal legs of these patients was noted in older females with femoral vein obstruction of the left leg, with a shorter number of days from the onset of symptoms or with higher values for the obesity index and calf circumference. Significant correlations between the MVO and the obesity index (r = -0.59), venous capacitance (VC, r = 0.49) and the number of days from the onset of symptoms (r = 0.40) were found in the normal right legs of these patients (n = 40). In the normal left legs (n = 16), on the other hand, significant correlations were found between the MVO and the VC (r = 0.65) and the MVO and age (r = -0.65).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Regulation of atrial natriuretic hormone production by triiodothyronine in cultured rat atrial myocytes.

Since thyroid hormones have been reported to increase the synthesis of rat atrial natriuretic hormone and its mRNA accumulation, we further investigated the mechanism of stimulation of rANH synthesis by T3 using cultured rat atrial myocytes. T3 (10(-9)-10(-7) mol/l) increased cellular content and secretion into the medium of immunoreactive rANH in a dose-dependent manner. However, the ratio of secreted/cellular rANH was not altered by the addition of T3. Furthermore, in both cellular and secreted rANH, the larger molecular form (gamma-rANH) apparently predominated over the smaller one (alpha-rANH), and this profile was not influenced by T3 (10(-7) mol/l). Although T3 (10(-9)-10(-7) mol/l) also increased cellular rANH mRNA accumulation, the ratio of cellular rANH/rANH mRNA was not changed. Moreover, using actinomycin D, we found that T3 (10(-7) mol/l) did not affect the degradation of rANH mRNA. From these findings, we suggest that T3 has no specific effects on the translational and posttranslational processes and the release of rANH, but that T3 stimulates rANH synthesis in the pretranslational levels, probably in the transcriptional level of rANH gene.

Animals↗

PubMed1991

Signal peptide of the colicin E2 lysis protein causes host cell death.

Colicin E2 is encoded by the SOS-inducible colicin operon of plasmid ColE2-P9. Highly induced colicin E2 is excreted from the E. coli host cell, accompanied by quasi-lysis and cell death. These three events are all directed by the colicin lysis protein that comprises the signal peptide and a small mature lipoprotein. We constructed a mutant lysis gene encoding its complete signal peptide with addition of two external amino acids at the C-terminus. By using this mutant peptide as a reference, the wild type lysis signal peptide was identified and shown to remain quite stable after the cleavage. This mutant peptide also mimics the cleaved-off signal peptide avoiding the influence of the mature lysis lipoprotein, and suggested that cell death by the lysis protein, but neither colicin excretion nor quasi-lysis, is decided by the nature of its signal region.

Base Sequence↗