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Biomedical subjects

Y Kito

Publications and source records attributed to Y Kito.

At least 91 records · Page 5Linked to original sources
PubMed1990

[Middle term follow-up and comparative study of valve replacement with four kinds of new model bovine pericardial xenografts].

Our early clinical experience (up to 4 year's follow-up) with four new pericardial xenografts were reviewed. During the period July 1983 to December 1986, 148 Ionescu-Shiley Pericardial Xenografts (ISL) in 130 patients, 68 Carpentier-Edwards pericardial xenografts (CEP) in 65, 32 Mitroflow pericardial xenografts (MF) in 29 and 36 Hancock pericardial xenografts (HP) in 29 have been implanted. The actuarial survival rates at 3.3 years are 89.9 +/- 2.7% for ISL, 92.3 +/- 3.3% for CEP, 93.1 +/- 4.7% for MF and 93.1 +/- 4.7% for HP. Fifteen cases of primary tissue failure (PTF) were caused in all groups but CEP. The actuarial free rates from PTF at 3.3 years were 92.9 +/- 2.4% for ISL, 100% for CEP, 95.5 +/- 4.4% for MF, 82.6 +/- 7.9% for HP. All bioprostheses explanted because of PTF showed commissural tears occurred at the top of the stent posts or at the edge of the stent. In this respect, it is the reason why the cases with CEP were free from PTF that CEP has been achieved to be improved its frame design. The incidences of prosthetic valve endocarditis were not different among these kinds of bioprosthetic valves. The free rates from thromboembolism at 3.3 years were 97.5 +/- 1.5% for ISL, 98.3 +/- 1.7% for CEP, 96.0 +/- 3.9% for MF and 88.7 +/- 6.1% for HP. There was no patient with CEP and MF suffered from thromboembolism with sinus rhythm. In comparison of these 4 valves, we conclude that CEP is useful clinically because of its satisfactory durability and antithrombogenicity.

Adult↗
PubMed1989

[Surgical treatment of rheumatic tricuspid valve disease].

The rheumatic tricuspid valve is relatively rare in this country. We report the study on surgical treatment of 27 patients with rheumatic tricuspid valve. Surgical procedure on 7 cases out of them was tricuspid valve replacement (TVR) with bioprosthesis and tricuspid valvuloplasty (TVP) was performed in the remaining 20 cases. There were two operative deaths in TVR group, however, there were no major complications, such as thrombosed valve, the valve dysfunction or prosthetic valve endocarditis in the remaining five cases after the operation. The method of TVP in twenty cases consisted of two Kay's TAPs, six tricuspid commissurotomies (OTC), ten OTC with Key's TAPs and two OTC with DeVega's TAPs. Doppler cardiography (DCG) revealed residual tricuspid regurgitation (TR) more than 3/4 degrees in 7 cases of TVP group immediately after operation. Moreover, the increment of residual TR was seen in 7 cases during the following period and TVR was performed in 3 cases out of these 7 cases. In conclusion, it is suggested that TVR may be preferred to TVP for the rheumatic tricuspid valve because of severe residual TR in many cases of TVP group.

Bioprosthesis↗
PubMed1989

[Comparative analysis of long-term results with porcine-aortic, bovine pericardial and tilting disc valves].

The three series with the first-generation valve prostheses were reviewed for long-term clinical evaluation in isolated aortic and mitral valve replacement. Hancock porcine xenograft was implanted in 71 patients from 1977 to 1979, ionescu-Shiley pericardial xenograft (standard model) in 271 patients from 1979 to 1983, and Bjork-Shiley tilting disc valve in 194 from 1978 to 1986. In aortic position, no any significant difference among three valve types could be demonstrated in the actuarial survival and freedom from thromboembolism and valve infection, while the actuarial freedom from valve dysfunction in lonescu-Shiley valve was significantly lower than that in other two valves. Björk-Shiley valve in mitral position showed satisfactory clinical performance in terms of valve-related complications and survival in comparison with two types of bioprosthetic valves. In our conclusion at present time, Björk-Shiley valve is suitable for the first choice of both aortic and mitral valve prostheses. In case of valve replacement with a bioprosthesis, however, porcine aortic valve is a better choice for aortic, and bovine pericardial valve likely for mitral replacement.

Aortic Valve↗
PubMed1989

Treatment of acute myocardial infarction with cardiogenic shock using left ventricular assist device.

We have treated ten cardiogenic shock patients after acute myocardial infarction (AMI) with a left ventricular assist device (LVAD). These patients were later divided into three groups: the first group with ventricular septal perforation, the second with aorto-coronary bypass grafting (ACBG) before LVAD implantation and the third group without ACBG. LVAD maintained the systemic circulation in each group, and cardiac function recovered enough to remove LVAD in 70% of the total patients. Two of three patients in the first group were discharged from hospital. Two weaned cases in the second group died of multiple organ failure and one was discharged, and hemorrhagic necrosis was seen in the bypassed area of the myocardium. One patient of the third group could not be weaned from LVAD because of respiratory failure though his heart function began to recover. Another case in the third group underwent bypass grafting after removal of LVAD. However ACBG surgery should be done very carefully because a patient in shock is occasionally intolerant to major surgery. In all groups, the major cause of death was multiple organ failure which was probably caused by the prolonged low output condition prior to LVAD application. In the light of this experience, it appears that LVAD should be applied before irreversible damage occurs to major organs, including the heart itself. To ensure the timely application of LVAD, some way must be found to introduce systematic application of LVAD into the normal course of AMI treatment.

Aged↗
PubMed1989

[Results of tricuspid valve replacement using xenograft bioprostheses].

Thirty-two cases of tricuspid valve replacement were done with bioprostheses during the period from 1979 to 1986 at our institution. In these cases there were 19 cases of acquired valvular diseases, 10 cases of congenital types of heart diseases and other 2 cases were another genesis. Seven different kinds of bioprostheses were utilized: 30 were bovine pericardial xenografts and 2 were porcine xenografts. In postoperative hemodynamic study, right ventricular end-diastolic pressure and right atrial pressure significantly decreased after tricuspid valve replacement. RV ejection fraction were reduced but there was no statistic significance when compared to the preoperative data. There were 5 patients who showed postoperative atrio-ventricular block and two of them needed permanent pacemaker implantation. Six patients died in postoperative period and other 3 died in late follow-up period. However, these was no mortality directly related to prosthetic valvular failure. In follow-up study, there was no episode of valve thrombosis nor pulmonary embolism. Prosthetic endocarditis was not encountered during this observation period. One patient showed mild degree of tricuspid regurgitation who had severe pulmonary hypertension even after the operation. Based on our experience, we concluded that the bovine pericardial xenograft may be the best choice for the TVR because of its anti-thrombogenicity. However, mechanical valve will be better choice for the patients who are complicated with severe pulmonary hypertension.

Adult↗
PubMed1989

[Follow-up study of coronary artery bypass grafting after Kawasaki disease--early and late postoperative evaluation].

In our hospital, 22 patients with severe coronary arterial lesion after Kawasaki disease underwent coronary artery bypass grafting (CABG) since 1982. The age of the cases at surgery ranged from 1 year to 19 years. Mean age was 8.3 years. Fifteen cases were bypassed using internal mammary artery (IMA) and 5 cases using IMA and autologous saphenous vein (SVG). Two cases were bypassed using only SVG. They have been examined until now by catheterization, by Treadmill test, and by Tl-201 myocardial imaging, around 1 month (Study 1) and around 1 year (Study 2) after surgery for the evaluation of results of CABG. One patient died from acute myocardial infarction 3 months after surgery and one patient shows return of anginal attack due to graft stenosis. Other patients are almost uneventful. In the study 1,20 (100%) IMA were patent, and 7 (88%) SVG were patent. In the study 2, 11 (92%) IMA and 6 (67%) SVG remained patent. Development of left anterior descending artery distal to IMA anastomosis was shown in 8 cases in the study 2. On the follow-up study with TI-201 myocardial imaging, disappearance or decrease of perfusion defect was seen in 7 cases (59%) in the study 1 and 9 cases (75%) in the study 2. On the Treadmill test, disappearance or improvement of ischemic change was seen in 15 cases (88%) in the study 1 and 10 cases (84%) in the study 2. These results suggest that IMA is more preferable for than SVG for young children who has an indication of CABG after Kawasaki disease.

Adolescent↗
PubMed1989

[Late cardiac events of coronary bypass surgery].

The cardiac events of 598 patients undergoing coronary bypass surgery were analyzed. The hospital and late death was 4.9% and 3.8%, respectively. The late death were caused by cardiac events in 7 patients and non-cardiac events in 16 patients. Of 7 cardiac death, 5 patients were died of acute myocardial infarction (AMI), and 2 patients were died of congestive heart failure. 5-year survival rate, 5-year event free ratio, and 5-year non-cardiac event free ratio were 88%, 70% and 91%, respectively. Of 18 patients who suffered from AMI after operation, 5 patients died. The causes of AMI were grafts occlusion in 9 patients, progression of coronary lesions in 5 patients and unknown in 4 patients. PTCR, PTCA and rebypass surgery were performed in 4, 9 and 8 patients, respectively.

Adult↗
PubMed1989

[Surgical management of concomitant diseases of coronary and cerebral arteries--indication and late results].

Among 632 patients with isolated coronary artery bypass graftings (CABG), 77 patients had coexisting symptomatic or asymptomatic cerebrovascular diseases (group A). The other 555 patients had not concomitant cerebrovascular diseases (group B). Surgical and late mortality rate in group A and group B were 7.8%, 5.2%, and 6.4%, 3.6%, respectively. The late mortality rate in group A was significantly higher than those in group B. The cerebrovascular accident (CVA) rate in group A and group B were 5.2% and 1.3% in perioperative period, and 18.2% and 3.6% in late stage, respectively. The complication ratio of CVA after CABG were significantly higher in group A than those in groups B. In conclusion, the best surgical approach to the patients with combined coronary artery and cerebrovascular diseases who indicated CABG and extracranial to intracranial bypass graftinges (ECICG) were suggested as follows: 1) CABG is the first staged operation, if cerebrovascular disease is clinically stable. 2) ECICG for cerebrovascular disease is the first staged operation, if angina pectoris is clinically stable. 3) ECICG should be started in the first stage under the assist with IABP if both diseases in the crisis, and wait few days to perform CABG in the second stage, if possible. The simultaneous approach of CABG and ECICG should be the last of choice.

Cerebral Revascularization↗
PubMed1988

Amino acid sequence of the retinal binding site of squid visual pigment.

The retinylpeptides of visual pigments of two species of squid were identified in invertebrate visual pigments. Their primary structures were identical: H-Phe-Ala-Lys-Ala-Ser-Ala-Ile-His-Asn-pro-Hse(Met)-OH. The sequence was homologous to those of the corresponding region of other visual pigments, but the eighth amino acid, His, was found in squid visual pigments. In this experiment the retinylpeptides of eleven amino acid residues were isolated by monitoring the absorbance spectrum of the reduced retinal Schiff base without using radio-active [3H]retinal. This method is valid for the isolation and identification of retinylpeptides of other invertebrate visual pigments in which the chromophore is not exchangeable.

Amino Acid Sequence↗
PubMed1988

4-Hydroxyretinal, a new visual pigment chromophore found in the bioluminescent squid, Watasenia scintillans.

The bioluminescent squid, Watasenia scintillans has three visual pigments. The major pigment, based on retinal (lambda max 484 nm), is distributed over the whole retina. Another pigment based on 3-dehydroretinal (lambda max approximately 500 nm) and the third pigment (lambda max approximately 470 nm) are localized in the specific area of the ventral retina just receiving the downwelling light. Visual pigment was extracted and purified from the dissected retina. The chromophores were then extracted and analyzed with HPLC, NMR, infrared and mass spectroscopy, being compared with the synthetic 4-hydroxyretinal. A new retinal derivative, 11-cis-4-hydroxyretinal, is identified as the chromophore of the third visual pigment of the squid.

Animals↗
PubMed1988

Adaptation of a deep-sea cephalopod to the photic environment. Evidence for three visual pigments.

Watasenia scintillans, a bioluminescent deep-sea squid, has a specially developed eye with a large open pupil and three visual pigments. Photoreceptor cells (outer segment: 476 micron; inner segment: 99 micron) were long in the small area of the ventral retina receiving downwelling light, whereas they were short (outer segment: 207 micron; inner segment: 44 micron) in the other regions of the retina. The short photoreceptor cells contained the visual pigment with retinal (lambda max approximately 484 nm), probably for the purpose of adapting to their environmental light. The outer segment of the long photoreceptor cells consisted of two strata, a pinkish proximal area and a yellow distal area. The visual pigment with 3-dehydroretinal (lambda max approximately 500 nm) was located in the pinkish proximal area, giving high sensitivity at longer wavelengths. A newly found pigment (lambda max approximately 471 nm) was in the yellow distal area. The small area of the ventral retina containing two visual pigments is thought to have a high and broad spectral sensitivity, which is useful for distinguishing the bioluminescence of squids of the same species in their environmental downwelling light. These findings were obtained by partial bleaching of the extracted pigment from various areas of the retina and by high-performance liquid chromatographic analysis of the chromophore, complemented by microscopic observations.

Adaptation, Physiological↗