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Biomedical subjects

K Yasuda

Publications and source records attributed to K Yasuda.

At least 73 records · Page 4Linked to original sources
PubMed2002

Tubularized incised plate urethroplasty for distal hypospadia, using overlapping dorsal subcutaneous flaps.

This paper presents a newly developed simple procedure using overlapping vascularized dorsal dartos subcutaneous flaps to cover the neourethra after hypospadias correction. A 3-year old boy with distal hypospadias underwent the tubularized incised plate urethroplasty using this method. Postoperative complications, which include urethrocutaneous fistula, were not observed, but the glans did exhibit a vertical, slit-like meatus. Covering the neourethra with overlapping dorsal dartos flaps is expected to prevent the development of urethrocutaneous fistula in patients with distal hypospadias.

Child, Preschool↗
PubMed2002

The role of tissue macrophages in the induction of proinflammatory cytokine production following intravenous injection of lipoplexes.

Recent studies have demonstrated that intravenous administration of a plasmid DNA-cationic liposome complex (lipoplex) induced significant proinflammatory cytokine production in blood and inhibited transgene expression in pulmonary endothelial cells. In this study, we examined the effects of gadolinium chloride (GdCl(3)) pretreatment on the biodistribution and induction of proinflammatory cytokine production and transgene expression after intravenous injection of a lipoplex in mice. GdCl(3) is known to transiently deplete liver Kupffer cells and spleen macrophages after intravenous administration. Intravenous administration of a lipoplex triggers high levels of proinflammatory cytokine production, such as TNF-alpha, IFN-gamma and IL-12 in serum and a large amount of (32)P-labeled lipoplex accumulates in the liver 1 h after intravenous administration. However, pretreatment with GdCl(3) dramatically reduces serum levels of these cytokines and liver accumulation of the lipoplex. RT-PCR analysis showed that mRNA expression of TNF-alpha greatly increases in the liver and spleen after lipoplex injection and that pretreatment with GdCl(3) reduces mRNA expression in these organs. Messenger RNA expression of TNF-alpha in the liver occurs in non-parenchymal cells (sinusoidal endothelial cells and/or Kupffer cells). Inhibition of cytokine production by pretreatment with GdCl(3) leads to recovery of transgene expression in the lung following the second injection of lipoplex, which was reduced following the first injection of lipoplex. Thus, the present study demonstrates that tissue macrophages involving liver Kupffer cells and spleen macrophages are closely involved in TNF-alpha production following i.v. administration of the lipoplex. It is also suggested that avoiding lipoplex uptake and subsequent cytokine production by these cells would be a useful method of maintaining a high level of gene expression in the lung after repeated injections.

Animals↗
PubMed2002

Normalization of cytoplasmic calcium response in pancreatic beta-cells of spontaneously diabetic GK rat by the treatment with T-1095, a specific inhibitor of renal Na+-glucose co-transporters.

Chronic hyperglycemia is known to lead to a progressively further impaired insulin response and to hasten the development of complications in patients with type 2 diabetes, a notion referred as glucose toxicity. T-1095, a derivative of phlorizin, is a newly developed oral hypoglycemic agent that acts as a specific inhibitor of renal Na(+)-glucose co-transporters, reducing circulating blood glucose levels by promoting glucose excretion into urine. The effects of glycemic improvement by T-1095 on secretory function and cytoplasmic calcium response in pancreatic beta-cells were investigated using spontaneously diabetic GK rats. After four weeks of treatment with T-1095 (age 4 to 8 week rats), serum glucose and HbA1c levels were significantly improved (serum glucose level, GK vs. GK T-1095, 277.3 +/- 11.8 vs. 204.7 +/- 6.4 mg/dl; HbA1c level, GK vs. GK T-1095, 6.2 +/- 0.2 vs. 4.8 +/- 0.1 %). Insulin secretion induced by 16.7 mM glucose was also significantly increased in the T-1095-treated group compared to the untreated group. The [Ca(2+)]i response induced by 16.7 mM glucose in GK beta-cells was characterized by the loss of the steep first peak of [Ca(2+)]i elevation, and the lost first peak of [Ca(2+)]i reappeared in T-1095-treated beta-cells in 32 of 34 observations. In T-1095-treated beta-cells, the time lag to peak [Ca(2+)]i levels in the 16.7 mM glucose stimulation was significantly reduced (259.1 +/- 15.3 sec, p < 0.01) compared to untreated GK rats (524.7 +/- 52.9 sec). Thus, improvement of hyperglycemia by T-1095 ameliorates beta-cell function by relieving [Ca(2+)]i response.

Animals↗
PubMed2002

Fluid-dynamic characteristics of a bristled wing.

Thrips fly at a chord-based Reynolds number of approximately 10 using bristled rather than solid wings. We tested two dynamically scaled mechanical models of a thrips forewing. In the bristled design, cylindrical rods model the bristles of the forewing; the solid design was identical to the bristled one in shape, but the spaces between the 'bristles' were filled in by membrane. We studied four different motion patterns: (i) forward motion at a constant forward velocity, (ii) forward motion at a translational acceleration, (iii) rotational motion at a constant angular velocity and (iv) rotational motion at an angular acceleration. Fluid-dynamic forces acting on the bristled model wing were a little smaller than those on the solid wing. Therefore, the bristled wing of a thrips cannot be explained in terms of increased fluid-dynamic forces.

Acceleration↗
PubMed2002

The effect of increased stress on the patellar tendon.

We performed a biomechanical and histological study to clarify the effect of stress enhancement on the in situ frozen-thawed patellar tendon of the rabbit as a tendon autograft model. We used 48 Japanese White rabbits divided into three groups. In group 1, the patellar tendon underwent in situ freeze-thaw treatment with liquid nitrogen to kill intrinsic fibroblasts. In group 2, after similar treatment, the medial and lateral portions were resected so that the cross-sectional area was reduced by a third. In group 3, after treatment, the cross-sectional area was reduced by a half. In groups 2 and 3, the stress in the tendon was calculated theoretically to be 150% and 200% of the physiological stress during locomotion. Eight rabbits in each group were killed at three and six weeks, respectively. At three weeks, the mean values for the tensile strength of groups 2 and 3 were 113.7% and 75.7% of that of group 1, and at six weeks 101.2% and 57.4%, respectively. The tensile strength in group 3 was significantly lower than that in groups 1 and 2. The histological findings in group 2 were similar to those in group 1, although an acellular area appeared to be wider in the core portion compared with group 1 at each period. In group 3, the collagen bundles of the tendon were less organised than those of groups 1 and 2. Our findings showed that stress enhancement affects the remodelling of the frozen-thawed patellar tendon and that excessively high stress reduces the mechanical properties of the tendon. This indicates that high stress on the patellar tendon autograft should be avoided during ligament reconstruction.

Animals↗
PubMed2002

Popliteal venous aneurysms: involvement of tibial nerve in aneurysmal wall.

Primary popliteal venous aneurysms are very rare vascular abnormalities, with 50 cases reported in the English literature. Thromboembolic complications are common in popliteal venous aneurysms. Since medical treatment has been proved inadequate, surgical repair is recommended with a minimum time delay. However, it involves some risk because of the complex anatomy of the popliteal space. We report on a case of popliteal venous aneurysm, in which the tibial nerve was involved in the aneurysmal wall and was injured by surgical repair.

Adult↗
PubMed2002

Successful endovascular stent-grafting for thoracic aortic aneurysms in systemic lupus erithematosus. Report of 2 cases and review of the literature.

Systemic lupus erythematosus (SLE) is frequently associated with cardiovascular manifestations but rarely complicated with aortic disease, and surgical treatment is often complicated with later anastomotic dehiscence. We report successful endovascular stent-graft placement (EVSGP) as an alternative to conventional treatment of the aortic aneurysm in patients with SLE and review of the literature. Clinical cases included a 58-year-old woman with a saccular aneurysm of the distal aortic arch and a 52-year-old woman who had the aortic dissection in the whole descending thoracic aorta. Both patients underwent placement of the stent-graft in the diseased aorta through the iliac artery and received steroid perioperatively. Mortality was compared between surgical and medical treatment in the reported 39 cases of SLE associated with aortic aneurysm. Both patients were successfully treated by EVSGP and no inflammatory signs were seen after the procedure. There were no recurrence in the short follow-up period (up to 23 and 15 months after the procedure). In review of the literature, operative mortality (13.6%) was superior to that in patients receiving medical treatment only (53.3%), but two of 19 operative survivors died of rupture afterward. EVSGP can be a useful alternative to conventional treatment of the aortic aneurysm in patients with SLE, although it lacks the support of long-term follow-up data currently.

Adrenal Cortex Hormones↗
PubMed2002

[Early and long-term results of surgery for aortic arch aneurysms using selective cerebral perfusion].

OBJECTIVE: We report our operative technique for atherosclerotic arch aneurysms and early and long term results of the surgery. METHODS: Between April 1992 and December 2001, 80 consecutive patients underwent operation for atherosclerotic arch aneurysms. Their mean age was 70 +/- 7 years. Sixty-six (82.5%) patients were operated on electively. All operations were performed under median sternotomy using hypothermic circulatory arrest and selective antegrade cerebral perfusion. Total arch replacement was performed in 66 cases, proximal hemiarch replacement in 4 cases, distal arch replacement using stent graft implantation via aortic arch incision in 8 cases, and patch angioplasty in 2 cases. In 9 of these patients in whom mobile arch atheroma was revealed by intraoperative epiaortic ultrasonography, isolation technique was employed to avoid embolic stroke. RESULTS: Overall in-hospital mortality was 10.0% (8 of 80 patients). Postoperative temporary neurologic dysfunction was 7.5%, and stroke rate was 5.0%. The 3-year, and 5-year actuarial survival rate including hospital death was 79.3% and 75.3% respectively. The 3-year, and 5-year cardiovascular event free survival rate was 68.3% and 60.0% respectively. CONCLUSION: The early and long-term results of surgery for atherosclerotic arch aneurysms were acceptable. Selective cerebral perfusion is an effective brain protective adjunct.

Aged↗
PubMed2002

Prosthetic grafts for above-knee femoropopliteal bypass. A multicenter retrospective study of 564 grafts.

BACKGROUND: Many prosthetic grafts including expanded polytetrafluoroethylene (ePTFE) and polyethylene terephthalate (Dacron) have recently been used for above-knee femoropopliteal bypass. The purpose of this study was to identify the factors affecting patency performance and patient survival. METHODS: A multicenter retrospective analysis of 496 patients who received 564 grafts between 1990 and 1999 (325 ePTFE and 239 Dacron). Follow-up extended to 114.5 months, with a mean of 30.8 months (+/-25.9 months). RESULTS: The overall primary patency rate for all grafts was 71.4% at 5 years, 73.7% for ePTFE, and 68.9% for Dacron grafts. The secondary patency rates at 5 years were 84.1% for ePTFE, and 83.8% for Dacron. No significant differences were found. The logistic regression analysis revealed that younger age at operation and smoking history were correlated with decreased primary patency rate. The patency rates were unaffected by postoperative administration of oral anticoagulants or antiplatelet agents, although pharmacotherapy contributed to the improvement of survival rates. Renal failure, cerebral infarction and Dacron decreased survival rate. CONCLUSIONS: We conclude that the patency performances of prosthetic grafts are satisfying. However, the choice of prosthetic grafts for younger patients or patients with a smoking history need to be carefully considered. Cerebral infarction, chronic renal failure and Dacron grafts may decrease the survival rate. The operative indications should be determined carefully in these cases. The administration of beraprost sodium is recommended for postoperative pharmacotherapy.

Aged↗
PubMed2002

A rare case of atherosclerotic popliteal artery aneurysm in a young adult.

Popliteal artery aneurysms are not so clinically frequent but are the most common peripheral aneurysms. They usually affect older men aged over 60 and are caused by atherosclerosis. Whenever they occur in younger men, other more unusual etiologies such as trauma, infection, inflammatory arteritis or popliteal entrapment are responsible. In this paper we present the case of a young male with an atherosclerotic popliteal artery aneurysm without a history of penetrating trauma or other possible etiologies.

Adult↗
PubMed2002

[An evaluation of the potential ischemia of the forearm after harvesting of radial artery by near infrared spectroscopy].

We evaluated the potential ischemia of the forearm after harvesting of radial artery (RA) for coronary artery bypass grafting (CABG) by near infrared spectroscopy (NIRS). The subjects consist of two groups; patients group (group P) including 18 patients who received CABG with RA and control group (group C) including 9 healthy volunteers. Group P was divided into two groups; early post operative group (group E, n = 11) and mid-term post operative group (group M, n = 7). NIRS was used to measure the recovery time (RT) in the muscles of the forearm during occlusion test. There was a significant prolongation of the RT in group P than group C. There was no significant difference of the RT between group E and group M. In conclusion, harvesting of RA may cause ischemia of the forearm and it may continue for a long time.

Aged↗
PubMed2002

[Surgical results for aortic involvement in Marfan syndrome].

From 1991 through 2001, 21 Marfan patients underwent aortic operations in our hospital. They received a total of 36 aortic operations, 31 by ourselves including 4 non-elective operations and 2 operations before 1991. Extent of replacement was Bentall + total arch (4), Bentall (8), valve sparing aortic root (reimplantation) (2), re-anastomosis + coronary aortic bypass grafting (CABG) after Bentall (1), ascending + total arch (3), ascending (1), total arch (1), total thoracoabdominal (10), thoracoabdominal (1), descending thoracic (2), distal arch (1), abdominal (2). Multiple operations were required in 11 patients (2 operations in 7, 3 operations in 4). Eight reoperations in 6 patients were for adjacent lesion, 5 reoperations were for remote lesion, and 2 others were for complication of Bentall (initial operation elsewhere). Among the 8 reoperations for adjacent lesion, 3 were scheduled operation (2 with elephant trunk), 4 were for residual dissection, and 1 was for annulo-aortic ectasia (AAE). Total aortic replacement was achieved in 4 and subtotal replacement excluding the root in 2. There was no hospital mortality. Paraparesis occurred in 1 who died 4.7 years after operation. The remaining patients are currently alive. No other aortic event occurred. Aortic reoperation-free survival was 83% at 5 year and 28% at 10 year.

Adolescent↗
PubMed2002

Albumin-coated knitted Dacron aortic prosthses. Study of postoperative inflammatory reactions.

BACKGROUND: The purpose of this study was to investigate the postoperative inflammatory reactions to albumin-coated Dacron grafts (ACGs), which are used in the repair of abdominal aortic aneurysm (AAA). METHODS EXPERIMENTAL DESIGN: a retrospective study with a follow-up period of 14 days. SETTING: University hospital. PATIENTS: 50 patients admitted for elective AAA repair from January 1997 to January 2000. INTERVENTIONS: each patient underwent AAA repair with an ACG (Bard, albumin-coated Dacron graft). MEASURES: the white blood cell (WBC) count, plasma C-reactive protein (CRP) concentration, and body temperature (BT) were determined. The preoperative data, the highest values of the postoperative data, and the values 2 weeks postsurgery were analyzed. RESULTS: The BT, CRP, and WBC increased and peaked at the 1st week postsurgery and then decreased gradually. The BT and WBC levels returned to normal within 2 weeks. The CRP level continued to show slightly elevated values in the 2nd week, but it was not significantly different compared to the preoperative data. CONCLUSIONS: The use of an albumin-impregnated prosthesis for the reconstruction of AAA is biocompatible, since no significant increases in inflammatory reactions are observed in the 2nd week postsurgery.

Aged↗
PubMed2002

Combined spinal and epidural anesthesia for abdominal aortic aneurysm surgery in patients with severe chronic pulmonary obstructive disease.

BACKGROUND: The presence of chronic obstructive pulmonary disease (COPD) should not be considered a contraindication to operation but should rather identify those patients that require special preoperative and postoperative pulmonary care. The purpose of this paper is to report our experience in the use of combined spinal and epidural anesthesia (CSEA) for open AAA repair in such patients. METHODS: From April 1997 to November 1998, three patients with severe COPD underwent elective open infrarenal AAA repair under CSEA. All the patients satisfied one or more of the following criteria: a room air PaO2 =or<60 mmHg, PaCO2 =or>45 mmHg, FEV1 =or<50% of predicted, and/or FVC =or<75% of predicted, and one of them was on home oxygen preoperatively. Preoperative preparation of the patients consisted of breathing exercises with incentive espirometry, elimination of underlaying pulmonary infections and usage of bronchodilator therapy. RESULTS: All the patients tolerated surgery safely. None of them developed postoperative complications, including pneumonia and other respiratory conditions. No significant changes in room air arterial blood gas or pulmonary function was recognized before and after surgery. CONCLUSIONS: CSE anesthesia is a viable anesthetic option for conventional AAA surgery in patients with severe COPD since it can preserve spontaneous breathing and provide additional respiratory benefits over general anesthesia.

Aged↗
PubMed2002

Induction of angiotensin converting enzyme in neointima after intravascular stent placement.

BACKGROUND: To investigate the morphological changes of the arterial wall and the expression of angiotensin converting enzyme (ACE) in the arterial wall after stent placement in a canine model. METHODS: Seventeen mongrel dogs underwent stent placement (Gianturco's Z stent) in the aorta. Six animals were sacrificed at 4 weeks after stent implantation, and the other 5 animals at 12 weeks. The normal aorta was harvested from 6 dogs. The specimens were stained with hematoxylin-eosin (H&E) as well as by immunohistochemistry (smooth muscle specific a-actin, and ACE). Histomorphometric analysis was performed using the sections stained with H&E and smooth muscle specific a-actin. RESULTS: The total intimal area was significantly increased at all time points as compared with the control aorta. The a-actin positive intimal area was also significantly increased at all time points as compared with the control aorta. In the control aorta, luminal endothelial cells as well as a-actin positive medial cells occasionally exhibited faint cytoplasmic staining for ACE. In the 4- and 12-week stented aorta, a-actin positive cells in the neointima and media as well as macrophages in the adventitia stained strongly positive for ACE. CONCLUSIONS: ACE was induced in the neointima after stent placement of the canine aorta. Considering its multiple biological actions, ACE may be associated with the pathogenesis of neointimal hyperplasia after stent placement.

Actins↗
PubMed2001

Potent and selective ET-A antagonists. 2. Discovery and evaluation of potent and water soluble N-(6-(2-(aryloxy)ethoxy)-4-pyrimidinyl)sulfonamide derivatives.

In the preceding article,(1) we outlined the discovery and structure-activity relationship of a potent and selective ET(A) receptor antagonist 1 and its related compounds. Metabolites of 1 having potent selective ET(A) receptor antagonist activity were identified. This study suggested the metabolic pathways of 1 were considerably affected by species. Consequently, structural modification of 1 intended to improve the complexity of the metabolic pathway, and water solubility was performed. The subsequent introduction of a hydroxyl group into the tert-butyl moiety of 1 led to the discovery of our new clinical candidate, 6b, which showed a higher water solubility, a uniform metabolic pathway among species, and very high affinity and selectivity for the human ET(A) receptor (K(i) for ET(A) receptor: 0.015 +/- 0.004 nM; for ET(B) receptor: 41 +/- 21 nM).

Animals↗