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Biomedical subjects

S Fukunaga

Publications and source records attributed to S Fukunaga.

At least 91 records · Page 5Linked to original sources
PubMed1992

Effect of venous valves on grafts for coronary artery bypass.

The effect of venous valves on blood flow and patency in grafts of the long saphenous vein for coronary artery bypass is examined. Our experimental model involved both diastolic-predominant blood flow and transient systolic regurgitation, and the waveform was similar to that of in vivo coronary circulation. In this model, blood flow was assessed in the presence or absence of venous valves. It was found that coronary artery blood flow was significantly greater in the presence of venous valves. Angioendoscopy showed that the movement of the graft valves was strong and rhythmic. It seems that valve preservation may be desirable in grafts for coronary artery bypass.

Angiography↗
PubMed1992

Evaluation of high-frequency jet ventilation in oxygenation through an artificial membrane lung.

The membrane oxygenator often develops impaired gas exchange after prolonged use because plasma proteins adhere to the membrane's surface and leak through its micropores. This study was performed to examine the efficacy of high-frequency jet ventilation (HFJV) in minimizing these problems in a "flat plate" type of membrane oxygenator. We first vibrated the membrane of the oxygenator by HFJV from 1 to 10 Hz to find the frequency most effective for optimal gas exchange in animals with partial extracorporeal circulation. These studies suggested that 6 Hz HFJV was preferable in our model. We subsequently performed in vivo extracorporeal oxygenation in dogs for 8 h using the membrane oxygenator with or without 6 Hz HFJV. Although the gas exchange capacity within the first 8 h was similar in the two groups, after 6 h a significant decrease in the red blood cell count and in the hematocrit was found in the group not receiving HFJV. Scanning electron microscopic examination of the membranes after 8 h of use disclosed that the membrane from the group receiving HFJV had less plasma protein and fibrin adhesion than that from the group not receiving HFJV. Moreover, it appears that with prolonged extracorporeal oxygenation, 6 Hz HFJV also protects against a decrease in the hematocrit of the passed blood and might lead to enhanced gas exchange. Our data suggest that good gas exchange can be maintained for periods even longer than 8 h if HFJV is used in conjunction with the membrane oxygenator.

Animals↗
PubMed1992

[Coronary artery bypass grafting in a patient with Kawasaki disease].

A 3-year-girl admitted because of angina at rest. She had been diagnosed as Kawasaki disease at the age of 3 months. At that time, a coronary aneurysm was detected by echocardiogram and aspirin had started to administer. At the age of 4 months, a cardiac arrest occurred after severe heart attack because of inferior myocardial infarction. At the age of 2 years and 6 months, she started to complain of a chest pain even at rest. Coronary angiography was performed, and it showed total occlusion of RCA and LAD. However, LAD was vaguely filled by collateral flow from diagonal branch, and 201Tl scintigraphy showed myocardial viability of anteroseptal area. At operation, the size of ITA was 1.2 mm in diameter. Coronary artery bypass grafting to LAD by ITA was performed. Three weeks postoperatively, graft patency was confirmed by coronary angiography. The girl discharged with good ability of exercise. The ITA seemed to be the first choice of conduit for CABG even in a small child, and to be useful for progressive surgical treatment of Kawasaki disease.

Child, Preschool↗
PubMed1992

[The changes of the cell-mediated immunity in patients with administration of recombinant erythropoietin].

The change of cell-mediated immunity was studied in patients receiving open heart surgery with or without administration of recombinant erythropoietin (rEPO). Group I was not administered rEPO in 30 patients, and Group II was done intravenously with 200U/kg/day of rEPO for 6.4 +/- 2.4 days before operation and also for 7.2 +/- 3.6 days after operation in 20 patients. The ratio of reticulocyte increased in all patients receiving rEPO. In both groups the ratios of OKT3 and OKT4 positive T lymphocytes decreased significantly on postoperative day 1. However, the ratios in patients with rEPO increased more significantly than in those without rEPO. Lymphocyte blast formation which was indicated by PHA-SI (phytohemagglutinin stimulation index) increased after administration of rEPO. The postoperative PHA-SI in both groups showed similar changes. The level of interleukin-2 (IL-2) production increased after the administration similar to PHA-SI change. The level of it decreased on postoperative day 1 and increased on postoperative days 3 and 7. We administered 200U/kg/day of rEPO for 7 days in a patient with postoperative erythroderma after open heart surgery and the level of IL-2 production was found to also increase in patient according with recovery of symptom. In conclusion, our data suggested that the rEPO might effect on not only erythrocyte but also lymphocyte activation.

Adult↗
PubMed1990

The influence of materials difference on stress distribution and bone remodeling around alumina and titanium dental implants.

The long-term complications of dental implants are associated with loosening of the implant-bone interface, due to bone resorption and subsequent connective tissue interposing at the implant-bone interface. Mechanical stresses, which are induced in the surrounding bone, play a key role in the interface bone remodeling. In the present study, it is investigated how local stress patterns are associated with local bone structure. For identical geometry alumina, and titanium implants, the stress patterns, determined in the finite element models with boundary conditions, are compared with the local bone structure found in animal experiments. The results indicate that there appears to be relationship between the stress patterns and the bone remodeling at the implant-bone interface independently on the materials properties in alumina and titanium.

Aluminum Oxide↗
PubMed1988

Mechanics of percutaneous balloon valvotomy for mitral valvular stenosis.

The present study was performed to measure and calculate the mechanical force of percutaneous balloon valvotomy (PBV) for mitral valvular stenosis, using an equation pertaining to the mechanical force of the balloon needed to dilate the stenotic mitral valve. In case 1, the diameter of the mitral valve was enlarged by PBV from 1.43 cm to 2.40 cm and, in case 2, from 1.76 cm to 2.42 cm, with a mechanical force of 321 g and 436 g, respectively, following the equation.

Biomechanical Phenomena↗
PubMed1988

Chemotaxis for methamphetamine in Escherichia coli.

Escherichia coli showed the chemotactic response for methamphetamine, a biogenic stimulative amine. The response was qualitatively detected by using a paper disk filter. The quantitative assay showed that E. coli responded to methamphetamine at 10(-5) M or more.

Chemotaxis↗
PubMed1986

[Familial occurrence of intracerebral cavernous angioma].

A case of familial occurrence of intracerebral cavernous angioma is reported. The patients were a mother and her eldest son, a 48-year-old woman and a 28-year-old man, respectively. The mother, a hypovascular mass in the right frontal lobe was excised surgically, and in the son a well demarcated mass in the left temporal lobe was extirpated. Pathological examination in each case revealed cavernous angioma. Familial occurrence of intracerebral cavernous angioma is extremely rare. In the literature, 8 cases of familial occurrence have been reported, including our case, and in three out of the 8 cases the lesions were histologically confirmed. To our knowledge, this is the first case in Japan in which the diagnosis was established by surgical specimen. Of 17 cases in 8 family lines, multiple occurrence was observed in 7 cases. The clinical manifestations of the disease appear mostly in a form of adult epilepsy or intracerebral hematoma, and rarely sudden death associated with intracerebral hematoma. At present, CT scanning is widely used for diagnosis of the disease, and the lesions are surgically curable if they are located at the accessible sites. Although there has been no evidence of genetic basis, it is interesting that there is familial occurrence. From this point of view, we should carefully check the family tree of such patients.

Adult↗
PubMed1983

Effects of third ventricular injection of beta-endorphin on luteinizing hormone surges in female rat: sites and mechanisms of opioid actions in the brain.

The effects of third ventricular injection of beta-endorphin (beta-EP) on spontaneous, brain stimulation-induced and estrogen-induced LH surges were studied in the adult female rat. It was found that beta-EP blocked the preovulatory surge of LH release and ovulation, while it did not affect LH release in response to LH-RH injection. The site of the beta-EP blockade of ovulation was proved to be in the brain. Beta-EP completely blocked ovulatory LH release induced by the electrochemical stimulation of the medial amygdaloid nucleus and medial septum-diagonal band of Broca, but failed to block ovulation due to the stimulation of the medial preoptic area (MPO) or median eminence, though serum LH levels after the MPO stimulation were inhibited by beta-EP. In the spayed rats treated with estradiol benzoate (EB) on Day 1 and 4 of experiment, beta-EP given on Day 5 blocked the LH surge that normally occurred on that day and led to a compensatory surge of LH on the following day. Moreover, the LH surge on Day 5 was inhibited by beta-EP given either on Day 1 or Day 4. Present data suggest that beta-EP may act in inhibiting the preovulatory LH surges not only by suppressing the preoptic-tuberal LH-RH activities but also by affecting the initiation and development of stimulatory feedback of estrogen in the central nervous system.

Animals↗
PubMed1983

Instant shift from continuous flow assistance to paracorporeal diaphragm type pulsatile assistance.

Experiments were conducted implementing a special technique for shifting instantaneously from continuous flow to pulsatile flow assistance by using the assistant heart and obtaining the following results: Within only a few minutes, the shift could easily be made from one type of flow assistance to another on calves with normal hearts. In the 10 calves in which ventricular failure was produced, this instantaneous shift from continuous to pulsatile flow assistance brought about remarkable improvements in their hemodynamics. At the occurrence ventricular fibrillation in 6 of the calves, the return to sinus rhythm was possible with aid of this shift mechanism.

Acute Disease↗