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Biomedical subjects

K Yamane

Publications and source records attributed to K Yamane.

At least 181 records · Page 10Linked to original sources
PubMed1994

The rapid degradation of mutant SecA protein in the Bacillus subtilis secA341 (ts) mutant causes a protein translocation defect in the cell.

To study the function of SecA protein and the protein translocation system of Bacillus subtilis, wild-type and mutant SecA proteins were characterized in vivo and in vitro. SecA protein was abundant in a wild-type strain (168) and existed in a stable homodimer. In contrast to this, SecA341 (ts) protein having an amino acid replacement from proline to leucine at residue 431 was undetectable by immunoblotting in the cell lysate of a secA341 mutant (TB301) at the nonpermissive temperature, 42 degrees C. Pulse-chase studies using 35S-methionine showed that newly synthesized SecA protein was rapidly degraded in the mutant at 42 degrees C. Purified SecA341 protein was more sensitive to trypsin and subtilisin than purified wild-type SecA protein in the presence of ATP. These results indicate that the secA341 mutation causes the rapid degradation of mutant SecA protein and a concomitant protein translocation defect in the cell.

Adenosine Triphosphatases↗
PubMed1994

Endothelin and collagen vascular disease: a review with special reference to Raynaud's phenomenon and systemic sclerosis.

Endothelin-1 (ET-1), endothelin-2, and endothelin-3, a family of 21-aminoacid peptides, are potent, long-acting vasoconstrictors of mammalian blood vessels. Elevated levels of ET-1 have been found in the circulation of patients with various diseases, all of which have some degree of vascular involvement that is associated with endothelial cell activation. These diseases include systemic sclerosis, primary and secondary Raynaud's phenomenon, pulmonary hypertension, Buerger's disease, and Takayasu's arteritis. The role of circulating ET-1 in the pathogenesis of the vascular and fibrotic lesions in these conditions remains to be elucidated. This review focuses on the recent findings of the clinical significance and pathogenetic role of endothelin in collagen vascular diseases, especially in Raynaud's phenomenon and systemic sclerosis. Although the etiology of systemic sclerosis is unknown, a vascular pathogenesis is supported by a variety of clinical and laboratory observations. The fact that plasma levels of ET-1 are elevated in patients with systemic sclerosis and this elevation is more remarkable in patients with diffuse scleroderma compared with limited scleroderma patients might further support the vascular pathogenesis of systemic sclerosis.

Collagen Diseases↗
PubMed1994

Cavernous sinus cavernoma treated with radiation therapy--case report.

A 71-year-old female presented with a syncopal attack. She underwent surgery for what appeared to be a meningioma. However, a small incision in the dura mater caused severe bleeding. Histological examination of the biopsy specimen showed sinus cavernoma with an incomplete pseudocapsule. The dura mater encapsulated the cavernous sinus cavernoma, explaining the severe bleeding from the dural incision. She was treated with Linac irradiation (40 Gy) which resulted in a decrease in tumor size. Radiation therapy is indicated for the treatment of cavernous sinus cavernoma, especially if associated with severe intraoperative bleeding.

Aged↗
PubMed1994

[Nitroglycerin tape for Raynaud's phenomenon of rheumatic disease patients--an evaluation of skin temperature by thermography].

Topical nitroglycerin has been tried for the alleviation of Raynaud's phenomenon in rheumatic diseases, but its effect is not widely recognized. We evaluated the effect of nitroglycerin tape (NTG tape) for peripheral circulatory failure of 7 patients with rheumatic diseases (4 women and 3 men, aged 35-73 years). The underlying rheumatic diseases included: systemic sclerosis 4 patients, polyarteritis nodosa (PN) 1 patient, cutaneous PN 1 patient and digital microinfarction with pulmonary fibrosis 1 patient. An NTG tape (containing 2.5 mg of nitroglycerin) was applied unilaterally on one forearm or leg, and the change in skin temperature was evaluated by thermography. Skin temperature of the extremities significantly increased at 2 and 3 hours after the application of NTG tape. Feeling of cold and/or pain improved in all patients. Adverse effect was headache in one patient. These results suggest that NTG tape may deserve further use in the treatment of peripheral circulatory failure in patients with rheumatic diseases.

Administration, Cutaneous↗
PubMed1994

[Evaluation of Matas test by CBF studies, angiographic cross-filling and stump pressure in CEA patients].

Temporary and/or permanent occlusion of carotid artery is one of the most important strategy in the surgical treatment for cervical vascular and paraclinoid lesions. Cerebral ischemia produced by this procedure should be preoperatively grasped for the safety of the surgeries. Matas test has been widely applied to estimate the collateral blood flow at the main artery occlusion by observing only clinical features. In this study, we measured CBF and common carotid artery stump pressure (CCA stump P) in contrast to angiographic cross-filling in 43 carotid endarterectomy (CEA) patients to quantitatively evaluate Matas test. The patients were manually occluded the CCA on the affected side and clinically observed for at least 10 minutes. CCA stump P and cross-filling were evaluated in all patients and CBF measurements were carried out in the patients who clinically tolerated Matas test. CBF studies were performed by single photon emission CT with Xe-133 inhalation method and CBF values were obtained in the middle cerebral artery territory before and during Matas test. CCA stump P was measured during carotid angiography by manual occlusion of the proximal site of the CCA. Cross-filling was evaluated with the contralateral carotid angiography during the manual occlusion of the affected CCA. CBF changes in Matas test were classified into the following four patterns; bilateral mild decreases in CBF, unilateral severe decrease in CBF, unilateral mild decrease in CBF and no decrease in CBF. The frequency of bilateral mild decreases in CBF, unilateral severe decrease in CBF, unilateral mild decrease in CBF and no decrease in CBF were 8, 10, 14, 7 of 43 patients, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Ischemia↗
PubMed1994

[Near infrared spectrophotometric monitoring for cerebral ischemia during the occlusion of the internal carotid artery at CEA].

Near infrared spectrophotometry provides noninvasively real-time information on cerebral oxygenation and cerebral blood volume. Using this method of spectrophotometry we investigated the adequacy of collateral circulation during cross-clamping of the internal carotid artery in patients who underwent carotid endarterectomy. In 15 patients, oxy-hemoglobin, deoxyhemoglobin and total hemoglobin were monitored continuously by near infrared spectrophotometry at the ipsilateral frontal area on the operated side. Changes in these parameters following temporary cross-clamping of the internal carotid artery were evaluated. The stump pressure of the internal carotid artery was measured in every patient. Only the maximum decrease in oxy-hemoglobin during cross-clamping of the internal carotid artery correlated significantly with the stump pressure of the internal carotid artery. Changes in oxy-hemoglobin during cross-clamping of the internal carotid artery demonstrated three patterns; no change or minimally decreased (4 patients), decrease with recovery (4 patients), and decrease without recovery (7 patients). The stump pressure of the internal carotid artery in patients who had no recovery of their decreased oxy-Hb was significantly lower than that in any other pattern (p < 0.01, Mann-Whitney U analysis). Patients who experience decrease in oxy-Hb without recovery following cross-clamping of their internal carotid artery may have poor collateral circulation and therefore may develop cerebral ischemia.

Aged↗
PubMed1994

[Ruptured distal anterior cerebral artery aneurysms presenting with acute subdural hematoma: report of two cases].

Two cases of ruptured distal anterior cerebral-artery aneurysms presenting with acute subdural hematoma are reported. Case 1 was a 55-year-old male, who showed abrupt disturbance of consciousness. An emergency CT revealed acute subdural hematoma at the right parietal convexity and interhemispheric fissure with moderate midline shift. There was no evidence of subarachnoid hemorrhage. Right carotid angiography showed an aneurysm at the right distal anterior cerebral artery. An emergency external decompression was performed and the aneurysm was clipped successfully through the interhemispheric fissure. In the operative field, subarachnoid hemorrhage could not been seen, and the patient had uneventful recovery. Case 2 was a 66-year-old female, who complained of severe headache. She deteriorated rapidly and become comatous with development of anisocoria. An emergency CT revealed acute subdural hematoma on the bilateral parietal convexities and interhemispheric fissure with severe midline shift. There was no evidence of subarachnoid hemorrhage. Carotid angiography showed right distal anterior cerebral artery aneurysm. An emergency external decompression was performed, then the aneurysm was clipped successfully. She recovered with disorientation and hemiparesis. Ruptured distal anterior cerebral artery aneurysms presenting with acute subdural hematoma without subarachnoid hemorrhage are rare. It is suggested that CT scans and history of patients are most important but an emergency angiography was prerequisite for correct diagnosis. Surgical treatment should be the best management in such cases.

Acute Disease↗
PubMed1994

[Clinicopathoradiological studies in 15 cases of megadolichobasilar anomaly].

We clinicopathoradiologically assessed 15 angiographically diagnosed megadolichobasilar anomalies. Nine of the patients were male and 6 were female; their average age was 61 years. Eleven patients presented with cerebral ischemic attacks, other two complained of trigeminal neuralgia and the remaining two suffered severe headaches. Twelve of the patients had severe hypertension. Vertebral angiography revealed marked elongation of the basilar artery with severe tortuousity and dilatation. The average distance from the dorsum sellae to the basilar artery bifurcation on the lateral view was 24.7 mm, and the average maximum diameter of the basilar artery was 8.6 mm. Aneurysmal dilatation of the basilar artery was also observed in four cases. In 14 of the 15 patients CT scans revealed characteristic findings, such as tubular high density mass with evident contrast enhancement extending from the ventral medulla to the interpeduncular cistern. The outcome was extremely poor, with five deaths and four patients with severe dementia. In the two autopsy cases, enlarged internal lumens could be observed despite severe atheroscrelotic changes, such as intimal thickening by atheromas.

Aged↗
PubMed1994

[Evaluation of angiographic delayed vasospasm due to ruptured aneurysm in comparison with cerebral circulation time measured by IA-DSA].

Delayed vasospasm due to ruptured aneurysm has been basically evaluated by angiographic changes in contrast to clinical features such as delayed ischemic neurological deficits (DIND). However, the discrepancies between angiographic and clinical findings have been pointed out. In this study, angiographic changes and cerebral circulation time in ruptured aneurysms were simultaneously investigated with IA-DSA. Thirty-two patients, who had ruptured aneurysms at the anterior circle of Willis and neck clippings at the acute stage, were investigated. Carotid angiogram was performed with IA-DSA on the 7-13th day after the attack. Angiographic changes were evaluated by Fischer's classification and circulation time was calculated in the following way. A time-density curve was obtained at the two ROI's; the C3-C4 portion and the rolandic vein. Circulation time was defined by the difference between the time showing peak optical density at the carotid and the venous portion. The control value of this circulation time obtained from 20 cases with non-rupture aneurysm and epilepsy was 3.4 sec (53 year old) on the average. X-ray CT scan examination was performed at the same time and clinical features were observed everyday. Angiographically, 3 cases were free from vasospasm, 18 cases were found to present slight to moderate vasospasm, and 11 cases showed severe vasospasm. Circulation time in patients with no spasm was 3.6 seconds, in patients with slight to moderate vasospasm it was 4.3 seconds and in patients with severe vasospasm it was 6.8 seconds. Ten patients showing cerebral infarction on CT scans demonstrated significantly long circulation time, 7.0 second on the average.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Three histidine residues in the active center of cyclodextrin glucanotransferase from alkalophilic Bacillus sp. 1011: effects of the replacement on pH dependence and transition-state stabilization.

Cyclodextrin glucanotransferase (CGTase) catalyzes the formation of cyclodextrins from amylose through an intramolecular transglycosylation reaction. On the basis of the three-dimensional structures of CGTases three histidine residues, which are conserved between CGTases and alpha-amylases, are located at the active center and are proposed to constitute the substrate binding sites. The three histidine residues (His-140, His-233, and His-327) of CGTase from alkalophilic Bacillus sp. 1011 were individually replaced by site-directed mutagenesis to probe their roles in catalysis. Asparagine-replaced CGTases (H140N-, H233N-, and H327N-CGTase) retained cyclization activity but had altered production ratios of alpha-, beta-, and gamma-cyclodextrin. Replacement of histidine by asparagine residues strongly affected the kcat for beta-cyclodextrin-forming, coupling, and hydrolyzing activities, whereas it barely affected the Km values. The activation energies for alpha-cyclodextrin hydrolysis were increased more than 12 kJ/mol by the replacement. Furthermore, the Ki values of acarbose, which is thought to be a transition-state analog of glycosidase catalysis, were 2-3 orders of magnitude larger in asparagine-replaced CGTases than that in wild-type CGTase. Therefore, the three histidine residues participate in the stabilization of the transition state, whereas they participate little in ground-state substrate binding. H327N-CGTase had decreased activity over an alkaline pH range, indicating that His-327 is important for catalysis over an alkaline pH range.

Acarbose↗
PubMed1993

Nucleotide sequence of 5' portion of srfA that contains the region required for competence establishment in Bacillus subtilus.

The nucleotide sequence of the 20,535 base pairs of the 5' end of the srfA operon, containing the region required for competence development, was determined. This included the srfA promoter region, the first open reading frame, srfAA, encoding surfactin synthetase I and part of the second open reading frame, srfAB, encoding surfactin synthetase II. Three amino acid-activating domains characteristic of those found in peptide synthetases could be discerned in both srfAA (activating Glu, Leu and D-Leu) and srfAB (activating Val, Asp, and D-Leu). The presence of a conserved spacer motif in the amino-terminal end of srfAA suggests that the srfAA product may not initiate surfactin synthesis. The portion of srfA that contains the region required for competence is composed of srfAA and the first amino acid-activating domain of srfAB.

Amino Acid Sequence↗
PubMed1993

Extracellular production of human hepatitis B virus preS2 antigen as hybrid proteins with Bacillus subtilis alpha-amylases in high-salt-concentration media.

To produce PreS2 antigen of human hepatitis B virus extra-cellularly in Bacillus subtilis, it was fused with the COOH-termini of B. subtilis alpha-amylases of 522 (Amy+), 467 (Amy+) and 443 (Amy-) amino acids. Among them, alpha-amylase-A467, which has 467 amino acids, was a relatively stable carrier when the cells were cultured in Luria-Bertani (LB) medium. The alpha-amylase-A443-PreS2 hybrid protein (Amy-) was quickly degraded. The alpha-amylase-A522-PreS2 hybrid was most efficiently produced when a B. subtilis transformant of a protease-super-deficient mutant was cultured in the presence of 0.5 M sodium sulphate. The production of A522-PreS2 hybrid protein under such conditions reached 5-10 mg/l and was eight, and 200-500 times higher than those obtained by the transformants of an alkaline/neutral protease-deficient mutant of B. subtilis, and a wild-type strain, in LB medium, respectively.

Bacillus subtilis↗
PubMed1993

Westernized food habits and concentrations of serum lipids in the Japanese.

To investigate the association of westernized food habits and concentrations of serum lipids in the Japanese, we studied 1200 healthy Japanese living in Hiroshima prefecture and 1483 ethnic Japanese from Hiroshima prefecture living in the Hawaii Islands and Los Angeles. The nutritional assessments were made by the same dietitians. No major difference was observed in the total energy intake between the Japanese and the Japanese-Americans in both males and females. However, the intake of animal fat and simple carbohydrates (especially fructose) were markedly greater, and that of complex carbohydrates lower, in the Japanese-Americans compared with the Japanese. The mean serum cholesterol (CH), LDL-CH and serum triglyceride (TG) levels were significantly higher in the Japanese-Americans in both sexes. The mean HDL-CH concentration was similar between the two groups in males, but it was approximately 7 mg/dl higher in Japanese-American females. Using the 75 percentile values of CH and TG in the Japanese in Hiroshima, the frequency of WHO types IIa and IIb hyperlipidemia was about twice as high in the Japanese-Americans. These results suggest that westernized food habits in the Japanese include qualitative changes in animal fat, simple carbohydrate and complex carbohydrate diet rather than an increase in the total energy intake. These changes are associated with marked increases in the concentrations of serum CH and TG and increased prevalence of types IIa and IIb hyperlipidemia.

Adult↗
PubMed1993

Structural requirements of Bacillus subtilis alpha-amylase signal peptide for efficient processing: in vivo pulse-chase experiments with mutant signal peptides.

The Bacillus subtilis alpha-amylase signal peptide consists of 33 amino acids from its translation initiation site. To analyze the structural requirements for efficient processing of the signal peptide, single and repeated Ala-X-Ala sequences and their modifications were introduced into B. subtilis alpha-amylase signal peptides of different lengths and the mature thermostable alpha-amylase. Then the cleavage positions and processing rates of the signal peptides were analyzed by the NH2-terminal amino acid sequences of the exported thermostable alpha-amylases and by in vivo pulse-chase experiments. In B. subtilis, the most efficient cleavage site was located at the peptide bond between Ala-33 and amino acid X at position 34, even though Val-X-Ala and six repeating Ala-X-Ala sequences were present around the cleavage site. However, the cleavage site was shifted to the peptide bond between Ala-31 and amino acid X when Ala-33 was deleted, and it was also shifted to Ala-35 and X when Ala-33 was replaced with Val-33. The shorter signal peptide consisting of 31 amino acids reduced the processing rate and alpha-amylase production. In contrast, those signal peptides were cleaved preferentially at the peptide bond between Ala-31 and amino acid X in Escherichia coli. In addition to the presence of an Ala residue at the -1 amino acid position, the length of the signal peptide was another important requirement for efficient processing.

Alanine↗
PubMed1993

Cloning and characterization of a Bacillus subtilis gene encoding a homolog of the 54-kilodalton subunit of mammalian signal recognition particle and Escherichia coli Ffh.

By using a DNA fragment of Escherichia coli ffh as a probe, the Bacillus subtilis ffh gene was cloned. The complete nucleotide sequence of the cloned DNA revealed that it contained three open reading frames (ORFs). Their order in the region, given by the gene product, was suggested to be ORF1-Ffh-S16, according to their similarity to the gene products of E. coli, although ORF1 exhibited no significant identity with any other known proteins. The orf1 and ffh genes are organized into an operon. Genetic mapping of the ffh locus showed that the B. subtilis ffh gene is located near the pyr locus on the chromosome. The gene product of B. subtilis ffh shared 53.9 and 32.6% amino acid identity with E. coli Ffh and the canine 54-kDa subunit of signal recognition particle, respectively. Although there was low amino acid identity with the 54-kDa subunit of mammalian signal recognition particle, three GTP-binding motifs in the NH2-terminal half and amphipathic helical cores in the COOH-terminus were conserved. The depletion of ffh in B. subtilis led to growth arrest and drastic morphological changes. Furthermore, the translocation of beta-lactamase and alpha-amylase under the depleted condition was also defective.

Amino Acid Sequence↗