Search PubMed⌕ Search

Biomedical subjects

T Ohta

Publications and source records attributed to T Ohta.

At least 991 records · Page 55Linked to original sources
PubMed1991

[Factors regulating venous return: analysis based on the respiratory variations of superior vena caval flow].

Characteristics of venous return and its determining factors were observed using pulsed Doppler echocardiography. Superior vena caval (SVC) flow was regarded as representing venous return. Ten healthy subjects and 23 patients with chronic pulmonary disease were studied. 1. In the healthy subjects, the forward flow was biphasic with dominant systolic (S) wave. Among 23 patients, 18 had normal SVC flow patterns (Group I), while in the remaining 5, SVC flow showed disappearance of the diastolic (D) wave, or both the D and S waves (Group II). 2. The healthy subjects and Group I patients had negative pleural pressures during inspiration and expiration. Consistent findings in Group II patients included positive pleural pressures during expiration and reduction in FEV1.0%. In the normal subjects and Group I patients, right atrial (RA) pressure was less than the pressure of the subclavian vein (ScV) during an entire respiratory phase. However, in Group II, RA pressure was equal to or greater than ScV pressure during expiration, resulting in disappearance or reversal of the S and D waves. 3. Respiratory variation in pleural pressure correlated significantly with that of the S wave (r = 0.77) (p < 0.005), D wave (r = 0.80) (p < 0.005), x descent of RA pressure (r = 0.77) (p < 0.005), and y descent of RA pressure (r = 0.82) (p < 0.005). The present study clearly confirmed that the superior vena caval flow patterns were closely correlated with right heart hemodynamics and truly reflected the effects of pleural pressure.

Aged↗
PubMed1991

[Venous return disturbances in chronic pulmonary disease: a study using pulsed Doppler echocardiography].

Pulsed Doppler echocardiography was used for investigation of respiratory changes of superior vena caval flow in chronic pulmonary disease to analyze the mode of venous return and its regulating factors. The subjects consisted of 55 patients with various pulmonary diseases and 44 healthy controls. 1. In the controls, the velocities of the S and D waves increased during the inspiratory phase. 2. Patients with pulmonary diseases were categorized into 2 groups. One with the mode of the healthy subjects (normal pattern), and the other with disappearance of the D wave or both the S and D waves (abnormal pattern) in the expiratory phase. All patients with restricted ventilation exhibited the normal patterns, while the abnormal patterns were observed in some of the patients with obstructive ventilation, and most of the patients with combined ventilation. 3. The respiratory patterns of the pressure gradients between the right atrium and subclavian vein reflected patterns of the superior vena caval flow well. In cases with abnormal patterns, the right atrial pressure exceeded the subclavian vein pressure in the expiratory phase. 4. The velocity of the A wave at the expiratory phase correlated significantly with pulmonary vascular resistance and with the mean pulmonary artery pressure. In conclusion, the mode of venous return in patients with pulmonary disease varies depending on the mode of the ventilation disturbance and the presence of right ventricular pressure overload, which is most likely caused by the intrathoracic pressure and by right ventricular filling abnormalities.

Aged↗
PubMed1991

[A ruptured aneurysm in the hypoplastic proximal anterior cerebral artery (A1 portion); case report].

A case of ruptured aneurysm in the hypoplastic proximal anterior cerebral artery (A1 portion) is reported. This 25-years old man complained of the sudden onset of severe headache and vomiting on January 11, 1989. He was referred to our hospital on the same day, and CT scan revealed subarachnoid hemorrhage. Cerebral angiography on the next day revealed an aneurysm in the hypoplastic A1 portion of the right anterior cerebral artery, and no branch was present at the site of the aneurysmal neck. He was operated on using the right pterional approach. The A1 portion was trapped and the aneurysm was removed successfully. The histology of the aneurysm was that of the usual type of the saccular aneurysm. The post-operative course was uneventful. He was discharged with no neurological deficit two months after the operation. As far as we know, there has been no report on a ruptured aneurysm in the hypoplastic A1 portion. We also reviewed the 55 aneurysms in the A1 portion that have been reported in the literature.

Adult↗
PubMed1991

[Experimental study on local attachment of Beriplast P membrane including MMC].

We studied the effect of Beriplast P membrane including MMC (2 mg/ml) on human gastric carcinoma implanted in nude mouse (OSS) as a example of a shallow but broad lesion as with an early-stage local recurrence of rectal cancer and superficial gastric cancer. As a result, the resected tumor contact Beriplast P membrane including MMC after 3 days showed continuous necrotic lesions, from 1 to 2 mm in depth. No side effect was observed in nude mice. These results indicated that Beriplast P membrane including MMC is a useful chemotherapy against local cancerous lesion.

Animals↗
PubMed1991

[Ruptured intracranial aneurysm combined with multiple cerebral vessel anomalies; a case report].

We report a very rare case of subarachnoid hemorrhage associated with fenestration of the anterior cerebral artery (ACA), the accessory middle cerebral artery (A-MCA) and the duplication of the middle cerebral artery (D-MCA). It seems that this is the first report of these combined intracranial vascular anomalies, although many authors have reported each anomaly in isolation. A 50-year-old male visited a local physician complaining of the sudden onset of a severe pulsating headache. A lumbar puncture showed bloody cerebrospinal fluid, and he was transferred to our institution. An emergency CT scan showed no apparent subarachnoid hemorrhage, but the left internal carotid angiography showed a saccular aneurysm at the origin of the D-MCA. Other anomalies, such as the fenestration of the ACA and the A-MCA, were also apparent during angiography. The ruptured aneurysm was safely clipped on the next day and the patient was discharged with no neurological deficits three weeks after the operation. The incidence of fenestration of the ACA is 0.2% in the angiographic series, and 0.1-7.2% at autopsy. Fenestration of the ACA is thought to be less than that of the vertebral artery. Ever since it was proposed by Teal et al, the term A-MCA has been restricted to an artery that arises from the ACA, and a branch arising from the internal carotid artery has been termed as the D-MCA. These anomalous vessels supply the cortex in the distribution of the middle cerebral artery. The angiographic incidence of A-MCA is about 4%, and six cases of aneurysm located at the origin of the A-MCA have been reported so far.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid Artery, Internal↗
PubMed1991

[Duodenal varices treated successfully by percutaneous transhepatic obliteration: report of a case].

A 73-year-old female with bleeding from duodenal varices treated by percutaneous transhepatic obliteration (PTO) was reported. She was admitted to our hospital because of tarry stool and general malaise. Gastroduodenoscopy revealed tortous elevations in the descending part of the duodenum, and observed intermittent bleeding. Percutaneous transhepatic portography (PTP) was carried out. PTP revealed duodenal varices supplied via the inferior pancreaticoduodenal vein and drained to the inferior vena cava, and continuously obliterated by gelfoam. Duodenal varices disappeared after obliteration and we observed no recurrence of varices for a year endoscopically. In general, it is accepted that the causes of the upper gastrointestinal bleeding secondary to portal hypertension are esophagogastric varices, hemorrhagic gastritis, gastro-duodenal ulcer, and so on. However, we must keep in mind the case with duodenal varices in which bleedings are of unknown origin. We also reviewed duodenal varices reported in Japanese literature from 1968 to 1989.

Aged↗
PubMed1991

Crystallization of allosteric L-lactate dehydrogenase from Thermus caldophilus and preliminary crystallographic data.

L-Lactate dehydrogenase of Thermus caldophilus GK24 was purified from Escherichia coli containing an overexpression plasmid. The enzyme was crystallized from polyethylene glycol 6000 solutions without ligands by the hanging drop vapor diffusion method. Two forms of crystals were obtained. The crystals grown at pH 6.0 were characterized by means of an X-ray diffraction experiment, while those grown at pH 6.5 and 7.0 did not give detectable diffraction spots. The crystals grown at pH 6.0 belonged to monoclinic space group P2(1), the cell dimensions being a = 54.8 A, b = 138.2A, c = 86.1 A, and beta = 93.3 degrees. These crystals diffract to beyond 2.5 A spacing and are stable on X-ray irradiation.

Allosteric Regulation↗
PubMed1990

Isolation and identification of the gene of cholesterol oxidase from Brevibacterium sterolicum ATCC 21387, a widely used enzyme in clinical analysis.

The gene coding cholesterol oxidase (CHOD) from Brevibacterium sterolicum, which is widely used in clinical analysis, has been selected from pUC19-based gene bank in E. coli MM294 by colony-hybridization using synthetic DNA as probe. The gene was identified to encode the protein having the same amino acid sequence as that determined from amino-acid sequence analysis. The expression of the CHOD gene in E. coli was not observed, probably due to the transcription failure. Attempts are being made to express it in various hosts including Streptomyces lividans, Corynebacterium glutamicum, and B. sterolicum itself.

Amino Acid Sequence↗
PubMed1990

Cytosol type electrolyte medium suitable for long term growth of human cells with very low membrane potential.

Culture media for mammalian cells contain electrolytes at concentrations that approximate those of the extracellular fluid (ECF). However, we observed that HeLa strain cells can grow in a cytosol type, serum-free, high amino acid medium (KN13) in which the concentrations of K+, Mg2+ and Pi were increased to about 10 times those in ECF by replacing NaCl. The Ca2+ concentration of KN13 is 10% of that in ECF. The additions of Mg2+ and Pi are essential to prevent the harmful effect of a high concentration of K+ in the medium. Even an increase in the K/Na ratio to 7 and 9 permitted growth for at least 2 weeks and 4 days, respectively. HeLaP3 cells adapted to KN13 (HeLaK cells) have proliferated (4 fold/week) for 4 years in this medium. The Na,K-ATPase of HeLaK cells was the alpha 1 isoform. HeLaK cells in KN13 medium have a lower membrane potential (-3.0 +/- 6.1 mV) than that of the original HeLaP3 cells in DM160 (-26 +/- 10 mV).

Base Sequence↗
PubMed1990

Enhancement of the thermostability of subtilisin E by introduction of a disulfide bond engineered on the basis of structural comparison with a thermophilic serine protease.

Sites for Cys substitutions to form a disulfide bond were chosen in subtilisin E from Bacillus subtilis, a cysteine-free bacterial serine protease, based on the structure of aqualysin I of Thermus aquaticus YT-1 (a thermophilic subtilisin-type protease containing two disulfide bonds). Cys residues were introduced at positions 61 (wild-type, Gly) and 98 (Ser) in subtilisin E by site-directed mutagenesis. The Cys-61/Cys-98 mutant subtilisin appeared to form a disulfide bond spontaneously in the expression system used and showed a catalytic efficiency equivalent to that of the wild-type enzyme for hydrolysis of a synthetic peptide substrate. The thermodynamic characteristics of these enzymes were examined in terms of enzyme autolysis (t1/2) and thermal stability (Tm). The half-life of the Cys-61/Cys-98 mutant was found to be 2-3 times longer than that of the wild-type enzyme. Similar results were obtained by differential scanning calorimetry. The disulfide mutant showed a Tm of 63.0 degrees C, which was 4.5 degrees C higher than that observed for the wild-type enzyme. Under reducing conditions, however, the characteristics of the mutant enzyme were found to revert to those of the wild-type enzyme. These results strongly suggest that the introduction of a disulfide bond by site-directed mutagenesis enhanced the thermostability of subtilisin E without changing the catalytic efficiency of the enzyme.

Amino Acid Sequence↗
PubMed1990

Unique precursor structure of an extracellular protease, aqualysin I, with NH2- and COOH-terminal pro-sequences and its processing in Escherichia coli.

Aqualysin I is a subtilisin-type serine protease which is secreted into the culture medium by Thermus aquaticus YT-1, an extremely thermophilic Gram-negative bacterium. The nucleotide sequence of the entire gene for aqualysin I was determined, and the deduced amino acid sequence suggests that aqualysin I is produced as a large precursor, consisting of at least three portions, an NH2-terminal pre-pro-sequence (127 amino acid residues), the protease (281 residues), and a COOH-terminal pro-sequence (105 residues). When the cloned gene was expressed in Escherichia coli cells, aqualysin I was not secreted. However, a precursor of aqualysin I lacking the NH2-terminal pre-pro-sequence (38-kDa protein) accumulated in the membrane fraction. On treatment of the membrane fraction at 65 degrees C, enzymatically active aqualysin I (28-kDa protein) was produced in the soluble fraction. When the active site Ser residue was replaced with Ala, cells expressing the mutant gene accumulated a 48-kDa protein in the outer membrane fraction. The 48-kDa protein lacked the NH2-terminal 14 amino acid residues of the precursor, and heat treatment did not cause any subsequent processing of this precursor. These results indicate that the NH2-terminal signal sequence is cleaved off by a signal peptidase of E. coli, and that the NH2- and COOH-terminal pro-sequences are removed through the proteolytic activity of aqualysin I itself, in that order. These findings indicate a unique four-domain structure for the aqualysin I precursor; the signal sequence, the NH2-terminal pro-sequence, mature aqualysin I, and the COOH-terminal pro-sequence, from the NH2 to the COOH terminus.

Amino Acid Sequence↗
PubMed1990

[Study on neoadjuvant chemotherapy of Borrmann 4 type carcinoma of stomach and its clinical significance].

Considering a high potential of biological malignancies of Borrmann 4 type carcinoma (abbr., Borr. 4) of the stomach, preoperative induction (neoadjuvant) chemotherapy was applied to patients with Borr. 4 as an initial therapy. Anticancer drugs used in this study were FAM-OK432, sequential MTX-5Fu or UFT-M through aortic infusion or induced hypertension chemotherapy (IHC) in order to obtain selective enhancement of drug delivery into tumor tissue. These trials were carried out on 24 patients who had Borr. 4 type carcinoma. The response to neoadjuvant chemotherapy showed CR in 1 case, PR in 3 cases and MR in 4 cases. The objective improvement except the primary gastric lesion showed shrinking of distant metastatic lymph nodes along paraaorta or Virchow of 50% (5/10), disappearance of pleural or peritoneal fluids 85. 7% (6/7) and marked decrease of tumor marker such as CEA, CA19-9 or CA125 100% (12/12). In one of 5 cases showing morphological improvement of primary gastric lesion, no viable cancer cells were seen in the stomach associated with multiple foci of granulofibromatous lesion of regional nodes. In 17 cases of 24 total gastrectomy was done with extended lymphadenectomy (R2-R3). While there was no difference in the median survival time (MST) among curable resection group, MST of non-curable resection group with neoadjuvant chemotherapy showed a fairly good prognosis for 14 months as compared to that of 4 months without chemotherapy. As for disease-free survival, patients whose tumor showed a high response to neoadjuvant chemotherapy had a good prognosis in non-curable resection group (p less than 0.01). In conclusion our results demonstrated that patients whose tumor were effectively destroyed by neoadjuvant chemotherapy against Borr. 4 carcinoma of stomach had an improved prognosis.

Adult↗
PubMed1990

Inhibitory action of dantrolene on Ca-induced Ca2+ release from sarcoplasmic reticulum in guinea pig skeletal muscle.

The effects of dantrolene on the sarcoplasmic reticulum and contractile machinery were examined in skinned skeletal muscles of guinea pigs. Dantrolene inhibited Ca-induced Ca2+ release at 38 degrees C. The inhibitory effect of dantrolene on Ca2+ release was greater in the presence of caffeine or adenine nucleotide than in their absence at low Ca2+ concentrations. Dantrolene suppressed the maximum rate of Ca-induced Ca2+ release but did not affect the sensitivity to Ca2+. At 20 degrees C, however, dantrolene did not inhibit Ca2+ release induced by any Ca2+ concentration, regardless of the presence and absence of caffeine, adenine nucleotide or Mg2+. Ca2+ uptake into the sarcoplasmic reticulum and the Ca2+ sensitivity of the contractile machinery were not affected by dantrolene at 38 degrees C and 20 degrees C. These results suggest that dantrolene is a selective inhibitor of the Ca-induced Ca2+ release mechanism at physiological temperatures without having an effect on the Ca2+ pump of the sarcoplasmic reticulum or on the contractile machinery of skeletal muscle.

Adenine Nucleotides↗