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Biomedical subjects

A Yamaguchi

Publications and source records attributed to A Yamaguchi.

At least 379 records · Page 21Linked to original sources
PubMed1994

[A case report of disappearance of free internal thoracic artery graft stenosis].

We have experienced an interesting case of spontaneous disappearance of stenosis of the injured free internal thoracic artery graft six months after coronary artery bypass grafting. A 61-year-old male underwent coronary bypass surgery with in situ left internal thoracic artery (LITA)-left anterior descending (LAD) and free right internal thoracic artery (RITA)-first diagonal branch (D1) bypass at our hospital. Postoperative angiogram showed the stenosis of the distal portion of the free RITA. We judged it was the injury by the electrocautery when dissecting the RITA. He was admitted to our hospital and received repeat angiography because of recurrence of angina six months after surgery. Repeat angiogram showed the good patency of LITA and complete disappearance of the stenosis of the free RITA. We consider that this case proved the free ITA can be a living graft.

Coronary Artery Bypass↗
PubMed1994

Lymph node metastases from carcinoma of the gastric stump.

The incidence of metastases from gastric stump cancer to various regional lymph node stations was studied after meticulous node dissection in 87 patients, who had undergone curative resection. Fifty-five (63%) patients had microscopically involved nodes. The incidence of node metastases varied between 17% and 30% in the perigastric nodes (n 1), with the same incidence in second-station lymph nodes (n 2; nodes along the left gastric, common hepatic and splenic artery, or nodes at the splenic hilus) With respect to third-station lymph nodes (n 3), metastases in nodes in the hepatoduodenal ligament (No 12) and retropancreatic nodes (No 13) were found only in 2% and 8% of the cases, respectively, but there was a high incidence of metastases (14/54, 31%) in the nodes along the mesenteric root. The overall 5-year survival rate was 48% and those for n 1 and n 2 patients were 78%, and 41%, respectively. With regard to the third level lymph node station, no 5-year survivors were seen when there was nodal involvement in node station No. 12 or No. 13. However, involvement of nodes at the root of the mesentery was associated with a 5-year survival rate of 25%. These results suggest that resection of the second level lymph nodes station must be combined with total gastrectomy and distal pancreatectomy, and that the resection of the mesenteric root is very important in patients with a tumor invading the jejunum.

Female↗
PubMed1994

[Evaluation of the addition of counterpulsation to the partial left ventricular-femoral bypass for limitation of evolving myocardial infarction].

The effect of adding counterpulsation to a partial left ventricular bypass was evaluated in a canine model of acute myocardial ischemia by using a myocardial staining method. To establish a left ventricular bypass, a catheter consisting of bypass tube (90 cm in length and 15 Fr in inner diameter) and an accompanying intraaortic balloon as a single apparatus (Integrated Cardioassist Catheter; ICAC) was introduced into the left ventricle via the abdominal aorta. The left ventricular bypass was adjusted to 1 L/min. with or without counterpulsation with the aid of a centrifugal pump and IABP console. The use of the ICAC that provided pulsatile left ventricular bypass tended to raise the mean aortic pressure and cardiac output. Reduction of the tension time index was noted with the use of the ICAC in contrast to the control. And increment of the DPTI/TTI ratio was observed with the use of the ICAC in contrast to the control and partial left ventricular bypass alone. While the percentages of the region at risk were similar [17.3 +/- 9.5% (control), vs. 16.4 +/- 3.4% (partial left ventricular bypass alone) vs. 16.9 +/- 5.2% (ICAC)], the percentages of infarct sizes were reduced due to the use of counterpulsation. [61.9 +/- 12.2% (control), vs. 57.5 +/- 3.9% (partial left ventricular bypass alone) vs. 16.8 +/- 6.0% (ICAC)]. These results revealed that the addition of counterpulsation alleviates afterload reduction to the partial left ventricular bypass and was more beneficial to the reduction of the infarct size than partial left ventricular bypass alone.

Animals↗
PubMed1994

[Aortic valve replacement for a patient associated with severe liver cirrhosis].

A 55-year-old man who had severe aortic regurgitation by bacterial endocarditis associated with severe alcoholic liver cirrhosis admitted in our hospital for the treatment of congestive heart failure. ICG15' score was 45.0% and redox tolerance test score was 0.38 x 10(-2). Preoperative hepatic function state was estimated as Child B. Preoperative preparation for the liver cirrhosis was done with FFP and glucagon insulin treatment. Aortic valve replacement was performed under the pulsatile high flow and high perfusion pressure during cardiopulmonary bypass. Post operative course was fair and he discharged.

Aortic Valve↗
PubMed1994

[Operative strategy for redo heart valve operation].

Thirty-five redo heart valve operations were performed between Jan. 1990 and Dec. 1993 in Jichi Ohmiya Medical Center. Previous operations were mitral valve replacement (MVR) in 19, closed mitral commissurotomy in 1, open mitral commissurotomy in 6, aortic valve replacement (AVR) in 5, ASD repair in 3, VSD repair in 1. Thirty (85.7%) were in NYHA functional class III or less, and 5 (14.3%) were in functional class in IV. Twenty-three patients had undergone MVR, 5 AVR, 4 MVR+AVR, 2 TVR (TAP), 1 Cabrol operation, and 8 patients had undergone concomitant tricuspid valve repair. Emergent operation was none. Overall operative mortality was 5.7% (2/35), as the cause of death was low output syndrome. Chest CT was available for the evaluation of the distension of right atrium and right ventricle. Catastrophic hemorrhage by the injury of ascending aorta or right atrium during redo sternotomy was 4, but that was not the cause of death. We emphasize the necessity of the exposure of the femoral artery and the preparation for cardiopulmonary bypass before sternotomy. The extent of dissecting adhesion should be determined case by case respectively under consideration of the risk of cardiovascular injury and postoperative large bleeding. Furthermore the cannule of SVC or IVC with cuff was useful for the cases with strong adhesion.

Adult↗
PubMed1994

[A case of primary angiosarcoma of the heart].

We report a case of angiosarcoma of the right atrium, manifested as a cardiac tamponade. The patient was a 57-year-old man. Transesophageal echocardiographic examination revealed a pericardial effusion and an abnormal structure arising in the right atrium. Emergency operation was performed and the tumor in the right atrium was resected under cardiopulmonary bypass. The resected tumor measured 5.0 x 3.5 x 2.0 cm, and microscopic examination revealed an angiosarcoma. The patient was initially recovered, but he died of heart failure caused by the recurrence in the left ventricle on the 5th postoperative month.

Cardiac Tamponade↗
PubMed1994

[Study of 5'-DFUR treatment as postoperative adjuvant chemotherapy for stomach and colorectal cancer. Tokai GATS Group (pilot study)].

In order to study preliminary the safety of 5'-DFUR treatment as postoperative adjuvant therapy, intermittent and continuous treatment regimens were administered to patients undergoing curative resection of carcinomas of the stomach and the colorectum. Two treatment schedules were employed: 5'-DFUR was either given continuously in a daily oral dose of 600 mg/patient (continuous group) or for 2 weeks in a daily oral dose of 1,200 mg/patient followed by 2 weeks of no treatment (intermittent group). Twenty-one stomach cancer patients and 34 colorectal cancer patients were registered in the study. The rates of adverse drug reactions in the patients who completed treatment were 20.0% (2/10) in the continuous group and 50.0% (4/8) in the intermittent group of gastric cancer patients, and 16.6% (2/12) in the continuous group and 17.6% (3/17) in the intermittent group of colorectal cancer patients. The main adverse drug reactions were gastrointestinal symptoms. The incidence of diarrhea, a problematic side effect of 5'-DFUR, was 4.5% (1/22) in the continuous group and 12.0% (3/25) in the intermittent group. There were no statistically significant differences between the continuous group and the intermittent group in regard to the incidence of adverse drug reactions and survival rate. In addition, as there were no serious adverse drug reactions, both treatment regimens were demonstrated to be highly safe when administered as postoperative adjuvant therapy.

Administration, Oral↗
PubMed1994

[A case of advanced gastric cancer surviving 3 years and 6 months after resection of Krukenberg's tumor].

Total gastrectomy was performed in a patient with an advanced gastric cancer (stage III). One year and eleven months postoperatively, Krukenberg's tumor was recognized and the prognosis was considered to be poor. A recurrence of ascites was identified. After resection of tumor, CDDP was administered intraperitoneally, and 5-FU tablets were administered orally as a maintenance therapy for a long term. The patient has continued to be in a good condition without any sign of recurrence for three years and six months (ie, five years and five months after previous gastrectomy).

Administration, Oral↗
PubMed1994

[Replacement of ascending and proximal transverse aorta for a 90-year-old female with aortic dissection].

Successful replacement of ascending and proximal transverse aorta for a 90-year-old female with aortic dissection was achieved using selective cerebral perfusion with cold blood. The ascending aorta enlarged as a diameter of 7 cm and massive blood flow was recognized in the false lumen detected by CT scanning and echocardiography. After the core cooling by cardiopulmonary bypass (CPB), the branches of the aortic arch were cannulated and perfused with cold blood (16 degrees C) for cerebral protection. The time of CPB, cardiac arrest and selective cerebral perfusion was 153 min, 92 min and 35 min, respectively. Post operative course was uneventful. She discharged from the hospital 4 weeks after the operation.

Aged↗
PubMed1994

Evaluation of the pulsatility of a new pulsatile left ventricular assist device--the integrated cardioassist catheter--in dogs.

A new pulsatile left ventricle-femoral artery bypass system (integrated cardioassist catheter system) has been developed for rapid, percutaneous insertion as a left ventricular assist device. Previous experiments revealed its superiority over the intraaortic balloon pump system in maintaining the peripheral circulation and in improving myocardial blood flow and afterload. Our objective was to determine whether the pulsatility of left ventricular bypass of this system would be preferable for maintaining the peripheral circulation and managing the ischemic myocardium as compared with nonpulsatile left ventricular bypass. Ten dogs with profound heart failure were supported by this system. Their hemodynamic status and myocardial blood flow were measured under control, nonpulsatile left ventricular bypass, or synchronous pulsatile left ventricular bypass. Significant differences between the nonpulsatile bypass group and the pulsatile bypass group were observed in the mean increase in aortic pressure (3.5% versus 22.2%, respectively; p < 0.001), total cardiac output (13.0% versus 21.7%; p = 0.004), and myocardial blood flow (9.5% versus 21.8%; p < 0.001). No differences were found between groups in the decrease in left atrial pressure (-20.2% versus -20.2%; p > 0.05). The ratio of diastolic time index/tension time index was shown to be improved significantly in the pulsatile bypass group compared with that of control and nonpulsatile bypass groups (p < 0.001). Thus, the pulsatility of the integrated cardioassist catheter system may support the peripheral circulation and improve the myocardial blood flow and oxygen supply/demand ratio.

Animals↗
PubMed1994

[Application of PCPS (percutaneous cardiopulmonary support) to the resuscitation of DOA (dead on arrival) patients].

We report three cases of DOA patients who were resuscitated by using PCPS. All had resisted standard advanced life support methods. The conditions responsible for the heart arrest were acute myocardial infarction (AM1) in 2 (case 1 and 3) and subarachnoid hemorrhage (SAH) in the other (case 2). All 3 were resuscitated by PCPS. Case 1 survived with a slight neurological deficit. Case 2 succumbed to SAH 3 days later. Case 3 was transferred to left heart bypass but succumbed to hemorrhagic infarction of the brain 6 days later. Although this system allows rapid and simple deployment and provides a benefit in resuscitation of DOA patients in a state that is refractory to standard cardiopulmonary resuscitation, the problem of indication for resuscitation remains to be solved.

Angioplasty, Balloon, Coronary↗
PubMed1993

Second-site mutation of Ala-220 to Glu or Asp suppresses the mutation of Asp-285 to Asn in the transposon Tn10-encoded metal-tetracycline/H+ antiporter of Escherichia coli.

A carboxyl group of Asp-285 is essential for tetracycline/H+ antiport mediated by the transposon Tn10-encoded metal-tetracycline/H+ antiporter (TetA) of Escherichia coli (Yamaguchi, A., Akasaka, T., Ono, N., Someya, Y., Nakatani, M., and Sawai, T. (1992) J. Biol. Chem. 267, 7490-7498). Spontaneous tetracycline resistance revertants were isolated from E. coli cells carrying the Asn-285 mutant tetA gene. All of the revertants were due to the second-site mutation at codon 220 of GCG (Ala) to GAG (Glu). The Km value of the tetracycline transport mediated by the revertant TetA protein was about 4-fold higher than that of the wild-type, indicating that the revertant is a low affinity mutant. A Glu-220 and Asn-285 double mutant constructed by site-directed mutagenesis showed the same properties as the revertants, confirming that the mutation of Ala-220 is solely responsible for the suppression. The Asp-220 mutation of the Asn-285 mutant resulted in a lower level of restoration of the tetracycline resistance and the transport activity than in the case of the Glu-220 mutation. A single mutation replacing Ala-220 with Glu or Asp caused about a 2-4-fold decrease in the tetracycline resistance, but no crucial change in the transport activity. It is not likely that Glu-220 is required for a charge-neutralizing salt bridge because an unpaired negative charge in a Glu-220 or Asp-220 single mutant did not cause a serious change in the activity. An alternative explanation is reasonable; Asp-285 directly contributes to the binding of a cationic substrate, metal-tetracycline chelation complex, or proton, and an acidic residue at position 220 can take over the role of Asp-285.

Alanine↗
PubMed1993

The in vivo assembly and function of the N- and C-terminal halves of the Tn10-encoded TetA protein in Escherichia coli.

The tetA gene was cut into its N- and C-terminal halves at the central EcoRI site and the two halves were subcloned individually or together under a separate lac promoter/operator. The expression of the C-terminal half was detected with a C-terminal-specific antibody. The amount of the N-terminal half in the cytoplasmic membrane was not affected by the presence of the C-terminal half. In contrast, the amount of the C-terminal half in the membrane was increased in the presence of the N-terminal half, indicating that the N-terminal half helps the stable folding of the C-terminal half in the membrane. Each half individually showed no tetracycline transport activity, however, when both halves were expressed together, the resultant complex showed about 40% of the tetracycline transport activity of the wild-type per number of the C-terminals of TetA protein in the membrane.

Amino Acid Sequence↗
PubMed1993

Role of the conserved quartets of residues located in the N- and C-terminal halves of the transposon Tn10-encoded metal-tetracycline/H+ antiporter of Escherichia coli.

In the putative secondary structure of the transposon Tn10-encoded metal-tetracycline/H+ antiporter [Yamaguchi, et al. (1992) J. Biol. Chem. 267, 7490-7498], Tyr50-XXX-Gln54 in transmembrane helix 2 and Gly80-XXX-Asp84 in helix 3 are thought to face each other in the N-terminal region. At the corresponding positions in the C-terminal region, a similar quartet of residues, His257-XXX-Gln261 in helix 8 and Gly281-XXX-Asp285 in helix 9, is also located. The quartets involve the residues Asp84 and Asp285, which have been revealed to be essential for the tetracycline transport function. When Gln54 and Gln261 were replaced with Ala by site-directed mutagenesis, the active tetracycline transport activity decreased to about 10% and 40% of the wild-type level, respectively. The Km values of the Q54A and Q261A mutants for tetracycline were 140 and 160 microM, respectively, which are about 8-fold higher than that of the wild type. Thus, the two Gln residues may contribute to the substrate recognition. On the other hand, the replacement of Gly80 and Gly281 with Leu caused a complete loss of the transport activity, whereas the G80A and G281A mutants retained about 10% and 30% of the activity of the wild-type, respectively, suggesting that a bulky side chain at positions 80 and 281 causes steric hindrance of the transport. The mutation of Tyr50 to Ala or His caused a decrease in activity by a factor of about 3 without a significant change in the Km value, whereas the Y50C mutant showed no transport activity at all.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Effects of sulfhydryl reagents on the Cys65 mutant of the transposon Tn10-encoded metal-tetracycline/H+ antiporter of Escherichia coli.

The Cys65 mutant of the Tn10-encoded metal-tetracycline/H+ antiporter is the only one which is inactivated by sulfhydryl reagents among the Cys mutants of the putative loop2-3 region [Yamaguchi, A. et al. (1992) J. Biol. Chem. 267, 19155-19162]. The tetracycline transport activity of the Cys65 mutant was completely abolished by N-ethylmaleimide; however, methyl methanethiosulfonate only abolished 45% of the activity, even in the presence of an excess of the reagent. Since N-ethylmaleimide did not further inactivate the methyl methanethiosulfonate-treated antiporter, it is clear that the modified antiporter molecule with a small substituent, a thiomethyl group, had significant but lower activity than the unmodified antiporter. The binding of [14C]N-ethylmaleimide to the Cys65 mutant was inhibited in the presence of tetracycline. These findings indicate that position 65 is close to the site of the interaction with the substrate and the modification of the side chain at this position caused steric hindrance as to substrate translocation.

Amino Acid Sequence↗
PubMed1993

Analysis of proliferative activity using anti-proliferating cell nuclear antigen antibody in gastric cancer tissue specimens obtained by endoscopic biopsy.

BACKGROUND: Proliferative activities of tumors are thought to be prognostic features of malignant tumors, but their value as measured by proliferating cell nuclear antigen (PCNA) labeling remains unclear in gastric cancer. METHODS: PCNA labeling rates (LR) were quantified in 121 paraffin-embedded biopsy specimens from primary tumors by immunocytochemistry. RESULTS: Immunohistochemical analyses have demonstrated that PCNA presents an intense staining in the nuclei of tumor cells and mucous neck cells of gastric glands. The PCNA LR ranged from 12% to 79% (mean +/- standard deviation), and a significant correlation was found between bromodeoxyuridine labeling indices and PCNA LR: PCNA LR were closely associated with tumor size, serosal invasion, and nodal involvement. The patients with tumors with high PCNA LR (greater than 40%) were dead significantly earlier than were those with tumors with low PCNA LR: When the PCNA LR and all the clinicopathologic parameters were entered into a Cox regression model, PCNA LR emerged as an independent prognostic factor. CONCLUSION: These results indicate that PCNA LR may be a potentially useful prognostic factor for gastric cancer.

Antibodies↗