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Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 775 records · Page 43Linked to original sources
PubMed1996

[A case of intrathoracic goiter].

Intrathoracic goiter is an uncommon conditional lesion. A case of intrathoracic goiter in a 66-year-old woman is herein described. Her chief complaint was anterior chest opplession. A computed tomographic scan and magnetic resonance imaging (MRI) revealed intrathoracic goiter pressed the trachea to the right side. The tumor was safety and completely took by collar incision without thoracotomy. Histologically, the mass was diagnosed the adenomatous goiter. In this case, MRI was very useful to be determined the surgical approach.

Aged↗
PubMed1996

Directly visualized cerebral circulation during retrograde cerebral perfusion.

BACKGROUND: Retrograde cerebral perfusion (RCP) was clinically introduced as a supportive technique to protect the brain during operations on the thoracic aorta. However, it remains unclear whether this procedure provides adequate blood supply for the brain. METHODS: We have observed the optic fundus of patients undergoing operation on the thoracic aorta to evaluate the cerebral circulation during RCP. There were 1 male and 3 female patients, ages ranged from 34 to 78 years. RCP time ranged from 39 to 70 minutes, and blood flow via the superior vena cava cannula ranged from 200 to 400 ml/min. RESULTS: The arteries of the retina showed marked constrictions soon after the initiation of RCP. The veins showed almost normal diameter. The large arteries were reduced to thin threads, while the smaller arteries were invisible at 30 minutes after the initiation of retrograde cerebral perfusion. CONCLUSION: Ophthalmoscopic findings demonstrate the reduction of cerebral blood flow, especially in arteries, during RCP. Although RCP is a useful technique for cerebral protection, it could be mentioned that the blood supply to the brain by RCP is not enough to maintain good cerebral metabolism.

Adult↗
PubMed1996

A simple technique for the prevention of lower limb ischemia during femoral veno-arterial cardiopulmonary support.

OBJECTIVE: We describe a simple technique to prevent the lower limb ischemia during femoral veno-arterial cardiopulmonary support (CPS). PATIENTS: Between July 1994 and September 1995, five patients underwent the insertion of femoral veno-arterial CPS with distal limb perfusion for the treatment of circulatory collapse after cardiac surgery. METHODS: After CPS is established, the ipsilateral superficial femoral artery (SFA) is punctured downward with a 14-gauge Teflon catheter and connected to the side port of the membrane oxygenator. RESULTS: None of the patients were complicated by lower limb ischemia for up to 77 hrs on CPS with distal limb perfusion. CONCLUSIONS: Active perfusion through a 14-gauge Teflon catheter downstream to the ipsilateral SFA is effective in preventing lower limb ischemia during prolonged femoral veno-arterial CPS after cardiac surgery.

Adult↗
PubMed1996

Non clamping anastomosis of the ascending and arch aneurysm using retrograde cerebral perfusion.

Twelve consecutive patients requiring surgery for replacement of ascending aortic aneurysms (n = 3), ascending arch aortic aneurysms (n = 2), or type A aortic dissections (n = 7) were treated without aortic cross clamping. Retrograde cerebral perfusion (RCP) with circulatory arrest (mean RCP time: 46.0 +/- 15.9 minutes, range 20 to 65 minutes) and continuous retrograde cardioplegia (mean cardiac ischemic time: 134.4 +/- 39.7 minutes, range: 40 to 180 minutes) were employed. In the patients with aortic dissection, the intimal tear at the origin of the brachiocephalic artery (BCA) was resected completely, the aortic wall was trimmed and closed with Teflon felt. The distal anastomosis was created using an open technique. Air and debris were completely evacuated by returning blood from the cerebral vessels and femoral artery. Then the artificial graft was clamped, and cardiopulmonary bypass resumed. The proximal anastomosis was performed during rewarming. The operations were elective in seven cases, and emergent in five cases. Graft replacement of the ascending aorta was performed in ten patients (including two BCA reconstructions). The remaining two patients were treated by patch repair (n = 1), primary anastomosis (n = 1). There were no perioperative deaths. One patient had a transient neurological deficit. The distal false lumen was occluded completely in five of seven patients with aortic dissections. The other two patients had a secondary tears in the descending aorta. Thus retrograde cerebral perfusion and continuous retrograde cardioplegia without aortic cross clamping is an effective technique in the replacement of the ascending and arch aorta.

Adult↗
PubMed1996

[Shock].

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Humans↗
PubMed1996

Experimental studies on modified human ureter as an arterial substitution for reconstruction of small caliber vessels.

Human ureters were experimentally employed as vascular biografts for small-caliber vessels. They were produced by tanning with polyepoxy compound or glutaraldehyde, and also were compared with saphenous veins tanned by polyepoxy compound and/or ready-made vascular graft of polytetrafluoroethylene (e-PTFE). These produced grafts, which had enough elasticity and excellent durability were successfully implanted to the carotid arteries in Japanese white rabbits. The grafts were sacrificed after 1 month observation. In this model there were no evidence of rejection, aneurysmal formation and/or infection. Polyepoxy compound fixed human ureter (n = 6), polyepoxy compound fixed saphenous vein (n = 6) and e-PTFE (n =3) showed good patency, but all glutaraldehyde fixed human ureters (n = 3) were completely occluded with severe intimal hyperplasia. Especially, polyepoxy compound fixed human ureter showed excellent patency as well as function, and the histological findings revealed monolayer endothelial cells covering the surface of the graft. No intimal hyperplasia was demonstrated at the anastomotic site. This study suggested that the polyepoxy compound fixed human ureter could serve as a satisfactory blood conduit of reconstruction for the small caliber vessels. Our preliminary data also suggests that longer observation up to 6 months in polyepoxy compound fixed human ureter graft and 18 months in polyepoxy compound fixed saphenous vein graft after surgery, arteriovenous shunt (A-V shunt), long bypass with a graft length of 2 to 5 cm), Y-graft model, sequential model and reinforcement graft by dacron cloth give good results.

Arteries↗
PubMed1996

A new simplified method for laser sinus node modification without electrophysiological technique.

As the treatment of inappropriate sinus tachycardia, beta-adrenoreceptor blockade therapy is the most common method for pharmacological heart rate control, but it is occasionally limited by side effects of the drugs, especially in patients with cardiac dysfunction. On the other hand, cryoablation or surgical exclusion of the sinus node have not been accepted generally for their necessity of permanent pacemaker implantation. Modification of the sinus node function is a new method of nonpharmacological treatments, although the skillfull and troublesome technique is required. In this study, the efficacy and safety of laser sinus node modification without electrophysiological technique were investigated as a new simplified method. In six mongrel dogs, the laser-tissue interactions by epicardial Nd-YAG laser irradiation were investigated by measuring the diameter and the depth of the irradiated lesions. Laser irradiations were performed from the head to the tail on the sinus node areas directed only by terminal groove for the visual landmark without electrophysiological technique until about 25% decrease in heart rate occurred in other six open-chest dogs.

Animals↗
PubMed1995

Reduced cell motility and enhanced focal adhesion contact formation in cells from FAK-deficient mice.

The intracellular protein tyrosine kinase FAK (focal adhesion kinase) was originally identified gy its high level of tyrosine phosphorylation in v-src-transformed cells. FAK is also highly phosphorylated during early development. In cultured cells it is localized to focal adhesion contacts and becomes phosphorylated and activated in response to integrin-mediated binding of cells to the extracellular matrix, suggesting an important role in cell adhesion and/or migration. We have generated FAK-deficient mice by gene targeting to examine the role of FAK during development. Mutant embryos displayed a general defect of mesoderm development, and cells from these embryos had reduced mobility in vitro. Surprisingly, the number of focal adhesions was increased in FAK-deficient cells, suggesting that FAK may be involved in the turnover of focal adhesion contacts during cell migration.

Animals↗
PubMed1995

Quantitative analysis of synaptogenesis in the inner plexiform layer of macaque monkey fovea.

Synaptogenesis has been tracked by using quantitative electron microscopic methods in the inner plexiform layer (IPL) of the developing Macaca monkey fovea from fetal day (Fd) 55 to Fd132. Vesicle-containing profiles were classified according to whether (1) they contained a ribbon indicating that they originated from a bipolar cell, or (2) the profile formed a junction. Group 2 was further subdivided by morphological characteristics into (2a) amacrine, (2b) bipolar, or (2c) unknown profiles. Ribbon-containing bipolar profiles are clearly identifiable at Fd55 when they occur at a density of 0.9/100 microns2. Bipolar synapses increase rapidly to 4.7/100 microns2 by Fd88, similar to their density at Fd132. Identifiable amacrine profiles forming a junction are rare at Fd55-68. By Fd88, amacrine synaptic density has jumped to 6.7/100 microns2 and continues to increase to 9.5/100 microns2 at Fd132. These quantitative data strongly suggest that, at the Macaca fovea, bipolar synaptogenesis both begins and ends before amacrine synaptogenesis. The large number of immature amacrine synaptic profiles and densities at Fd132 suggests that amacrine synapses continue to form after Fd132. This study confirms that cone-dominated monkey fovea has a different sequence of synaptogenesis than the rod-dominated peripheral retina (Nishimura and Rakic, [1985] J. Comp. Neurol 241:420-434). The data support the concept that synaptic developmental sequence is determined by the type of photoreceptor which dominates a particular retinal region or species. Bipolar ribbon synapses are observed in the outer half of the IPL at Fd55, are present in the inner IPL at Fd60, and then, with increasing age, are found throughout the IPL. This pattern strongly suggests that vertical OFF bipolar pathways form earlier than ON pathways in the IPL. In contrast, amacrine profiles are found throughout the IPL at the youngest ages, with an adult-like banding pattern present by Fd132.

Age Distribution↗