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Biomedical subjects

S Shimokawa

Publications and source records attributed to S Shimokawa.

At least 127 records · Page 7Linked to original sources
PubMed1993

Site-directed mutagenesis of hGH at the 54-74 loop selectively modifies its lactogenic receptor-mediated biological activity.

Four analogues of human growth hormone (hGH) mutated by site-directed mutagenesis at the 54-74 loop-Met-hGH(P59A), Met-hGH(P61A), Met-hGH(P59A,P61A) and Met-hGH(Des 62-67) were analyzed for: (1) their biological activity mediated through lactogenic receptors using rat lymphoma Nb2-11C cell proliferation and mouse mammary gland HC-11 cell beta-casein synthesis bioassays and (2) their ability to interact with recombinant hGH binding protein (hGHBP). The analogues Met-hGH(P59A), Met-hGH(P61A) and Met-hGH(P59A,P61A) partially lost their activity relative to native hGH in the HC-11, but not in the Nb2-11C cell bioassay. These analogues were nevertheless capable of forming a 1:2 complex with a recombinant hGH binding protein (hGHBP), despite the fact that the affinity of Met-hGH(P61A) and Met-hGH(P59A,P61A) analogues had decreased 8- and 14-fold, respectively. Met-hGH(Des 62-67) failed to form 1:1 or 1:2 complexes with hGHBP and did not compete with [125I]hGH for binding to hGHBP. It lost all biological activity in HC-11 cells, but retained 0.4% of its activity, in the Nb2-11C cell proliferation bioassay. These results confirm the involvement of Pro-61 in the hGH binding and activity mediated through somatogenic receptors, while the activity mediated through two different types of lactogenic receptors was selectively modified. These findings emphasize the fact that lactogen receptors in different species or organs are not identical.

Animals↗
PubMed1993

[Surgery for ventricular septal defect with aortic regurgitation].

Twenty-two patients (mean age of 12.9 years) with ventricular septal defect (VSD) associated with aortic regurgitation (AR) were treated surgically. Sixteen patients had subpulmonic VSD and six had infracristal VSD. Fourteen patients with subpulmonic VSD underwent VSD closure alone. VSD was closed by pulling up the inferior rim to the pulmonary valve thus support the prolapse aortic cusp. AR improved in two and has remained stable in eleven for 0.5 to 12.7 years (mean 4.4 years). Aortic valve replacement (AVR) was necessary in an adult patient later. Plication of the aortic valve was effective in a young patient but ineffective in an adult patient. In infracristal VSD, AVR was necessary in two adult patients. In a young patient, AR improved by plication. Direct VSD closure ceased progression of AR in three patients. The long-term follow-up shows that VSD closure with our technique has been sufficient to arrest progression of AR in subpulmonic VSD. Early closure of VSD should be emphasized to prevent aortic valve prolapse and regurgitation.

Adolescent↗
PubMed1993

[Gastrointestinal complication after open cardiac operation].

Seven cases of abdominal complications necessitated laparotomies within 30 days after open heart surgery are presented. They consist of five cases of mesenteric infarction, one acalculous cholecystitis and one hemorrhagic ulcer of the rectum. The incidence is 0.9 percent at our institute. They also had a very complex course after their cardiac surgery such as cardiogenic shock, respiratory failure and renal failure prior to the development of their acute surgical abdomen. It is proposed that the cause of acute abdomen is attributed basically to the low cardiac output state. Surgery must be performed without delay because unnecessary passage of time is accompanied by unacceptable mortality rate.

Abdomen, Acute↗
PubMed1993

[An operative case of empyema necessitatis].

A case of empyema necessitatis presenting a mass in the retroperitoneal space is reported. Computer tomography preoperatively revealed the transdiaphragmatic abscess with calcified capsule. The operation was performed by means of resection of the abscess together with overlying ribs. Dead space after resection of the lesion was filled up with intercostal muscles. Empyema necessitatis is rare after introduction of antituberculous drugs. However, recognition of this disease is necessary for an appropriate surgical management. Total resection of the abscess followed by filling of the dead space with the intercostal muscles should be considered as a useful alternative method.

Aged↗
PubMed1993

[Surgical treatment of primary cardiac tumors].

Thirty-four cases of primary cardiac tumors, consisted of 11 men and 23 women, aged between 26 and 80 years have been operated on in our institution. A total of 30 myxomas and four malignant tumors were resected. The clinical presentations included congestive heart failure in 25 patients, tachyarrhythmia in 6, chest pain in 4, and embolism in 10. All 30 myxoma lesions were completely resected, although none of the malignant tumors could be resected completely because of invasion of the tumor to the surrounding tissues. Four patients with malignant tumors died of tumor recurrence within 9 months after operation. Histological diagnosis was rhabdomyosarcoma in two patients, round cell sarcoma in one and malignant fibrous histiocytoma in one. All patients with myxoma survived operation. Follow-up was completed in 28 patients (range 1 month to 15 years, mean 5.5 years): Twenty-four were in New York Heart Association Class I, and the remaining two in Class II. Actuarial survival rate was 89% at 15 years after operation. No recurrent myxoma have been identified clinically or by echocardiography. For malignant primary tumors, more effective adjuvant therapy with aggressive resection will be inevitable to improve long-term prognosis.

Adult↗
PubMed1993

[Surgical repair of total anomalous pulmonary venous drainage--four adult cases of successful operation].

We have experienced four adult cases of total anomalous pulmonary venous drainage (TAPVD). They were three females and one male, age between 18-51 with a mean of 33.8. In Darling's classification, they constituted of three cases of type Ia and one type IV. Cardiac catheterization revealed 1.71-5.93 with a mean of 3.92 in Qp/Qs and 0.34-0.49 with a mean of 0.38 in Pp/Ps. The pulmonary to systemic resistance ratio (Rp/Rs) was then calculated as 0.02-0.15 with a mean of 0.09. All cases showed short route type of drainage vein in pulmonary arteriography. None of them had stenosis or obstruction in the drainage veins. The operation was composed of anastomosis between the left atrium and the common pulmonary vein, closure of the atrial septal defect (ASD), and ligation of the drainage vein. Gersony-Malm's method was adopted in two cases and the posterior approach in two cases in anastomoses between the left atrium and the common pulmonary vein. Intraatrial approach combined with posterior approach was tried in a case with small left atrium. The mean size of ASD was 43 mm (35-55 mm) in diameter. Patch closure was performed in three cases. Important factors in survival for adult TAPVD are large ASD and short route type drainage vein without stenosis. All of four cases had good results. The operation method is variable and an easier approach must be adopted.

Adolescent↗
PubMed1993

[Simultaneous cesarean section and mitral valve replacement for infective endocarditis during pregnancy--a case report].

Infective endocarditis (IE) during pregnancy is uncommon. A 31-week-pregnant, 21-year-old woman suffered from severe mitral regurgitation caused by IE. She fell into heart failure and threatened abortion. Following to cesarean section, an emergent mitral valve replacement with a bioprosthetic valve was successfully performed. Her postoperative recovery was uneventful and she was discharged home 30 days after the operation. Her baby, however, died of intracranial hemorrhage caused by hypoxia 171 days after delivery. A strategy of simultaneous open heart surgery and cesarean section is recommended when emergent open heart surgery is inevitable for the treatment of cardiac diseases in cases with 24 and/or more weeks' gestation.

Adult↗
PubMed1992

Comparison of the University of Wisconsin preservation solution and other crystalloid perfusates in a 30-hour rabbit lung preservation model.

The University of Wisconsin solution, which contains a high potassium concentration (120 mmol/L), was evaluated for rabbit lung preservation by comparing it with a modified University of Wisconsin solution with low potassium (4 mmol/L), a low-potassium dextran solution (4 mmol/L), and simple surface cooling. In the first three groups rabbit lungs were flushed in situ with the solution (n = 5 in each group); then the lung-heart block was harvested and stored at 10 degrees C for 30 hours. In the surface cooling group the lungs were harvested without flushing and then simply immersed in saline and stored. For assessment, the stored lung was ventilated with room air and perfused with fresh venous blood at a rate of 40 ml/min for 10 minutes. Assessment of lung function included gas analysis of effluent blood, mean pulmonary artery perfusion pressure, and peak airway pressure. Among these parameters, oxygen tension was most sensitive. Oxygen tension at 10 minutes' perfusion in the modified University of Wisconsin (95 +/- 6 mm Hg) and low-potassium dextran (99 +/- 4 mm Hg) groups was significantly higher than that in the surface cooling (61 +/- 7 mm Hg) and University of Wisconsin (51 +/- 7 mm Hg) groups. There was no difference between the modified University of Wisconsin and low-potassium dextran groups or between the surface cooling and University of Wisconsin groups. We conclude that the low-potassium University of Wisconsin solution is superior to the high-potassium University of Wisconsin solution and that the lactobionate and raffinose included in the University of Wisconsin solution as impermeants do not improve lung preservation in this model.

Adenosine↗
PubMed1992

[Bilocular pericardial cyst diagnosed by magnetic resonance imaging: a case report].

A 47-year-old female who had removal of pericardial cyst is reported. Preoperative examination including echocardiography, computed tomography and magnetic resonance imaging (MRI) demonstrated the cystic nature of the mass attaching to the right pericardial surface. MRI clearly revealed that the cyst was bilocular. MRI brings a more detailed information of pericardial cyst for surgery.

Female↗
PubMed1992

Variations in warfarin concentration in blood and coagulant factors after artificial valve replacement.

A proper dosage of warfarin after artificial cardiac valve replacements has been determined as an indication of coagulation activity. In some cases, the coagulation activity cannot be maintained within the therapeutic range because Prothrombin time (PT) values deviated from Thrombotest (TT) values. Here we studied each relationship between warfarin concentrations in blood, coagulation activity, vitamin Ks and other coagulation-related agents which were measured in patients administered warfarin after artificial cardiac valve replacements and whose coagulation activity was maintained within a therapeutic range, and in patients whose PT values deviated from TT values. The obtained results were interpreted as follows. 1) There was a high correlation between values from Thromborel S (a clot method) and values from Chromoquick (a method using a synthesized substrate). Since TT values had little variations compared to PT values, the former was an excellent indication of coagulation activity. 2) There was no correlation between warfarin concentrations in blood and coagulation activity in the group in which warfarin concentrations in blood vary within a day (Group B); but there was highly reverse correlation in the group in which warfarin concentrations in blood vary with days (Group A). 3) There was good correlation between warfarin concentrations and PIVKA-II concentrations in blood in Group A. Further, the concentration of Gla-Protein C was one microgram/ml or less on the fourth day from the initiation of warfarin administration. 4) For example, a patient whose PT value of 67% deviated from TT value of 19% on the eleventh day from the initiation of warfarin administration had vitamin K1-epoxide concentration of 2.68 ng/ml and MK-7 concentration of 1.26 ng/ml on the same day, respectively, which were higher levels than those in Group A.

Aged↗
PubMed1991

Surgical treatment of abdominal aortic aneurysm in the high-risk patient.

In an attempt to define the preoperative risk factors that predictably influence mortality after aneurysmectomy, this study reviews the surgical management of abdominal aortic aneurysms in a series of 110 consecutive patients who underwent elective resection. The preoperative risks to be added to the present study included pulmonary insufficiency, renal dysfunction, advanced age of over 80 years, ischemic heart disease, and associated other diseases such as thoracic aneurysms, atherosclerosis of the limbs and malignant tumors. Forty-six patients had one of these risk factors (one-risk group), 17 had two (two-risk group), and 9 had three (three-risk group). The operative mortality rates were 4.2 per cent for the high-risk patients and 0 per cent for the patients at no risk. As the number of risk factors increased, aneurysm repair was associated with an increased operative mortality; being 2.2 per cent in the one-risk group, 5.9 per cent in the two-risk group and 11.1 per cent in the three-risk group. The common risk factor in patients who died after aneurysmectomy was pulmonary insufficiency which induced prolonged periods of assisted ventilation. Thus, the optimal management of high-risk patients, particularly those with pulmonary insufficiency, may reduce the mortality after aneurysmectomy.

Aged↗
PubMed1991

Influence of intraalveolar oxygen concentration on lung preservation in a rabbit model.

We previously reported the use of an inexpensive screening model for lung preservation involving ventilation and perfusion of excised rabbit lungs after their preservation. We now have extended this model by perfusing the preserved lung in cross circulation with an anesthetized rabbit to permit stable reperfusion of the preserved lungs for 60 minutes. With this model we compared the results of lung preservation with the lungs inflated with nitrogen, room air, or 100% oxygen during 24 hours of hypothermic storage. Four groups of animals were studied: group 1, excision and immediate evaluation; group 2, inflation with room air and storage for 24 hours at 10 degrees C; group 3, same as group 2, with 100% oxygen for inflation during storage; group 4, same as group 2, with 100% nitrogen for inflation during storage. Assessment of the ex vivo perfused lung consisted of (1) blood gas analysis of inflow and outflow blood at 10-minute intervals; (2) continuous pulmonary artery and airway pressure monitoring; (3) measurement of pulmonary venous oxygen tension after 1 hour of reperfusion, with inflow oxygen tension adjusted to 15 mm Hg; (4) wet/dry weight ratio. We conclude that the paracorporeal circuit does not, in itself, cause lung injury over a 1-hour period; lungs preserved with nitrogen inflation rapidly became edematous and failed to function on reperfusion. Preservation with 100% oxygen inflation appears superior to inflation with room air.

Animals↗
PubMed1991

[Myocardial protection with verapamil in open cardiac surgery--a clinical study for the optimal use].

To determine the optimal use of Verapamil as a myocardial protective agent during open heart surgery, patients were divided into 3 groups of 15 patients each of the same severity and operative difficulty. In group I, Verapamil was added to the blood cardioplegia in a concentration of 1 mg/L. In group II, 0.2 mg/kg of verapamil was added in the pump prime and in group III, in addition to the same amount of pump prime, an additional 0.1 mg/kg of Verapamil was added to the bypass circuit at 60 minutes after the start of bypass and continuous drip of 0.5 micrograms/kg/min for 24 hours after surgery. Only group III continued to maintain an effective concentration of verapamil, that was said in a range between 15 and 100 ng/ml in the serum during and after surgery. It is suggested from the present study that recommendable verapamil administration is as in group III with no severe arrhythmias, significantly less usage of catecholamines without mortality.

Cardiac Surgical Procedures↗
PubMed1991

[Surgical management of tricuspid regurgitation associated with acquired valvular disease].

The best means of managing tricuspid regurgitation associated with acquired valvular disease is still controversial. During the period from 1978 to 1988, 111 patients who had tricuspid regurgitation along with associated valvular dysfunction were treated in Kagoshima University Hospital. Patients with moderate to severe regurgitation underwent annuloplasty in 61 (Carpentier's in 39, DeVega's in 20, and Kay's method in 2) and valve replacement in 8. Forty-two patients were treated conservatively on the tricuspid valve because of mild regurgitation. We found the results to be less satisfactory with a high incidence of postoperative deaths and residual tricuspid regurgatation in the group treated by annuloplasty with a Carpentier ring than in the other two groups of annuloplasty or in the group of valve replacement. We conclude the modified DeVega's method is the first choice for annuloplasty in patients with mild to moderate regurgitation, and we believe it appropriate to replace the valve in an increasing number of subjects which have severe regurgitation.

Adult↗
PubMed1991

[Nonsurgical removal of the embolized catheter fragments from the heart and great vessels].

Embolized catheter fragments in the heart and great vessels were successfully removed in seven patients by nonsurgical techniques. All procedures for the retrieval were completed without complications or difficulty using instruments such as multipurpose grasping forceps, stone basket, loopsnare and myocardial biopsy catheters. Embolized catheter fragments should be removed promptly before fatal complications develop, and can be taken off safely and simply by nonsurgical technique.

Aged↗
PubMed1990

An active site of growth hormone for eliciting the differentiation of preadipose 3T3-F442A cells to adipose cells.

In order to elucidate the active sites of growth hormone for eliciting the differentiation of preadipose 3T3-F442A cells to adipocytes, four artificial mutant variants of human growth hormone (hGH) modified in the loop region of amino acid residues 54-74 were prepared in Escherichia coli by site-directed mutagenesis. Although the P59A (replacement of Pro59 with Ala) variant retained almost the same biological- and receptor binding-activity as hGH, the P61A (replacement of Pro61 with Ala) and the P59A-P61A (replacement of both Pro59 and Pro61 with Ala) both exhibited about half the activity, and the delta (62-67) variant (deletion of the residues 62-67) exhibited only about 0.1% the activity of those of intact hGH. The results suggest that Pro61 may be involved in formation of the active conformation of hGH, but Pro59 may not, and that the amino acid residues around 62-67 may be critical for the specific biological features of hGH.

Adipose Tissue↗