Hiroaki Takenaka

Neovascularization induced by autologous bone marrow cell implantation in peripheral arterial disease.

Neovascularization has recently been used as a new treatment for severe ischemic disease. We tried to induce therapeutic neovascularization by autologous bone marrow cell implantation (BMCI) in eight selected patients with chronic peripheral arterial disease (PAD), in whom traditional treatments had failed. Improvement of subjective symptoms was seen in seven patients after treatment. Of three limbs with toe or finger ulceration, complete healing was achieved in two, while the other one became less severe after treatment. No relative toxicity was observed in any of the patients. BMCI might be a feasible treatment for selected patients with chronic PAD.

Is endovascular treatment of abdominal aortic aneurysms less invasive regarding the biological responses

To compare the biological responses following an endoluminal repair and a conventional open repair of abdominal aortic aneurysm (AAA), 14 patients who underwent an endoluminal repair (endograft group) and 26 who underwent an open repair (open group) were investigated. As markers of biological responses, interleukin-6 (IL-6) and -8 (IL-8), granulocyte elastase (GEL), white blood cell count (WBC), and serum C-reactive protein (CRP) were all measured preoperatively as well as on postoperative days (POD) 1, 3, and 6. In addition, the blood loss, duration of surgery, initial oral intake the day after surgery, and length of hospital stay were compared between both groups. The plasma levels of IL-6, GEL, CRP, and WBC were higher in the endograft group than in the open group, while the CRP, WBC, and GEL levels all peaked on POD 3. The plasma level of IL-6 remained high in the endograft group, compared with that in the open group throughout the study period. Conversely, blood loss, initial oral intake the day after surgery, and the length of hospital stay were all significantly greater in the open group than in the endograft group, although there was no significant difference in the duration of surgery between the two groups. These findings indicate that although the endoluminal repair of AAA is supposed to be less invasive, the biological responses tend to be greater because of the manipulation related to the insertion of the stent graft.

Matrix Metalloproteinase Expressions in Arteriosclerotic Aneurysmal Disease

Medial degeneration of extracellular matrix (ECM) proteins in the wall of abdominal aortas results in smooth muscle cell destruction, a loss of architectural integrity, and abdominal aortic aneurysm (AAA) formation. It has been theorized that an imbalance between proteinases and their naturally occurring inhibitors is the cause of these observed histologic abnormalities. Therefore, the purpose of this investigation was to determine if differences in the matrix metalloproteinase (MMP) -2 and -9, tissue inhibitor of metalloproteinase-1 (TIMP-1), tissue-type plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA) protein and activity levels existed between infrarenal AAA and normal abdominal aortic tissue specimens. Between November 1995 and January 1997, 10 patients undergoing elective infrarenal AAA repair had a portion of their aneurysm walls snap frozen in liquid nitrogen and processed for subsequent western blot or zymographic analysis. Tissue specimens from 6 normal abdominal aortas obtained from fresh cadaver specimens were similarly processed and served as controls. Protein levels for MMP-2, MMP-9, TIMP-1, uPA, and tPA were analyzed by western blotting. The degree of MMP-2 and MMP-9 gelatinolytic activity was analyzed by zymography. Detection and immunolocalization for MMP-2, MMP-9 and CD68 was performed on tissue sections of AAA and normal infrarenal abdominal aortas fixed in 10% formalin. MMP-9 and tPA protein levels were increased in AAAs compared to controls by western blotting. However, uPA levels were slightly increased in controls. No differences in TIMP-1 protein levels were identified. Similarly, zymography demonstrated increased MMP-2 and MMP-9 gelatinolytic activity in AAAs compared to controls (p<0.05). CD68-positive cells (macrophages) in the adventitia and media demonstrated immunoreactivity to MMP-9. This investigation demonstrated increased MMP-9 proteinase activity and tPA protein levels in the walls of AAAs, as well as inflammatory leukocyte invasion of the adventitia and media compared to controls. These data suggest that leukocyte-derived MMP-9 is associated with aortic wall degeneration and aneurysm formation. Furthermore, activation of MMP-9 may be caused by increased tPA levels in the walls of AAAs.

L-Type calcium channel blockers modulate the microvascular hyperpermeability induced by platelet-activating factor in vivo

PURPOSE Platelet-activating factor (PAF) is a potent phospholipid mediator of the microvascular dysfunction associated with ischemia-reperfusion injury. Because changes in cytosolic-free Ca2+ concentration are essential in PAF cellular signaling, we formulated the hypothesis that blockade of Ca2+ entry may inhibit the PAF-induced microvascular dysfunction. METHODS To investigate this hypothesis two L-type calcium channel blockers, verapamil and nifedipine, were applied to the hamster cheek pouch before the topical PAF challenge was undertaken. Permeability was assessed by measurement of the plasma clearance of fluorescein isothiocyanate dextran, 150,000 mol wt. The arteriolar diameter was measured simultaneously to evaluate the effects of L-type calcium channel blockers on PAF-induced vasoconstriction. RESULTS Baseline clearance was 498.7 +/- 225.0 nl/60 min/gm (mean +/- SE). PAF at 10(-8) mol/L (n = 5) increased clearance to 3753.8 +/- 572.8 nl/60 min/gm (p < 0.01). Pretreatment with verapamil (2 mg/kg; n = 5) significantly reduced the increase in permeability caused by 10(-8) mol/L PAF (1909.1 +/- 620.2 nl/60 min/gm; p < 0.05). Nifedipine (5-10(-6) mol/L; n = 5) also significantly attenuated the impact of 10(-8) mol/L PAF (2037.2 +/- 427.5 nl/60 min/gm; p < 0.05). Neither verapamil nor nifedipine affected PAF-induced vasoconstriction. CONCLUSION The significant inhibition of the increase in permeability by the L-type calcium channel blockers suggests that these compounds may be useful in the management of PAF-induced hyperpermeability.

Sutureless anastomosis of blood vessels using cyanoacrylate adhesives.

On the assumption that the remaining suture threads of the anastomotic line play an important role in the progression of anastomotic neointimal hyperplasia, we performed an experimental study on the sutureless anastomosis of blood vessels. An expanded polytetrafluoroethylene graft, 5 mm in diameter and 2 cm in length, was implanted on the abdominal aorta of mongrel adult using one of three methods of anastomosis, namely; a continuous suture, a stay suture, or sutureless anastomosis. Overall patency rates were 83.3 per cent, 91.7 per cent and 75.0 per cent respectively. The thickness of the pannus in the distal anastomotic line after 12 months was 107 μm in one graft in the continuous suture group, 106 μm and 222 μm in 2 grafts each in the stay suture group, and 41 μm and 117 μm in 2 grafts each in the sutureless group. Because there were cases of patency even after 12 months with a very small pannus thickness, sutureless anastomosis is considered to be a useful method of preventing anastomotic neointimal hyperplasia.

Fatal Diffuse Atheromatous Embolization Following Endovascular Grafting for an Abdominal Aortic Aneurysm : Report of a Case

Abstract A 78-year-old woman with an abdominal aortic aneurysm, 57 mm in diameter, was admitted to our hospital for endovascular grafting. Preoperative computed tomography and angiography showed friable mural thrombus in the suprarenal and infrarenal aorta, and a diagnosis of shaggy aorta was made. Postoperatively, the patient suffered cerebral infarction, and disseminated intravascular coagulopathy with multiple organ failure developed, resulting in early death on the third day after surgery. An autopsy revealed diffuse atheromatous embolization into the celiac, superior mesenteric, bilateral renal, bilateral hypogastric (trash buttock), and peripheral arteries. This case report serves to demonstrate that an abdominal aortic aneurysm with a shaggy aorta in the proximal neck is a contraindication to endovascular grafting, and that predicting the possibility of diffuse atheromatous embolization by detecting a shaggy aorta is the best way to prevent this catastrophic complication.

Right axillary cannulation in the left thoracotomy for thoracic aortic aneurysm

Perfusion from the femoral artery is commonly used in the open proximal method of performing distal aortic arch aneurysm repair or Stanford type B aortic dissection repair under circulatory arrest through left thoracotomy. However, it is associated with a significant risk of retrograde emboli or malperfusion, and with other problems including a restricted time of circulatory arrest to the brain and difficulties in de-airing from the arch branches and proximal ascending aorta. To overcome these problems, we developed a method of performing right axillary perfusion through left thoracotomy.

Microvascular transport is associated with TNF plasma levels and protein synthesis in postischemic muscle

To better understand the mechanisms of ischemia-reperfusion (I/R) injury, we tested the hypothesis that protein synthesis is involved in the production of tumor necrosis factor (TNF) and in the microvascular transport changes in I/R. To evaluate the hypothesis, we inhibited protein synthesis with topically applied actinomycin D (AMD), measured I/R-induced changes in microvascular transport, and bioassayed the venous plasma levels of TNF. The rat cremaster muscle I/R model consisted of 4 h of ischemia followed by 2 h of reperfusion. Changes in transport were determined by integrated optical intensity (IOI) using FITC-Dextran 150 as tracer. Animals were separated into four groups: 1) control (C), 2) control treated with AMD (C + AMD), 3) I/R, and 4) I/R treated with AMD (I/R + AMD). The mean (+/-SE) maximal IOI in C and C + AMD were 3.0 +/- 1.0 and 3. 7 +/- 0.7 units, respectively. I/R elevated mean maximal IOI to 21.8 +/- 1.9 units (P < 0.05 vs. C, C + AMD, I/R + AMD). Treatment with AMD reduced the I/R-induced mean maximal IOI to 9.7 +/- 2.0 units (P < 0.05 vs. I/R). In I/R group, plasma TNF levels increased (relative to preischemia baseline) immediately after the release of the vascular occlusion to 250 pg/ml and reached a peak value of 342 pg/ml at 60 min of reperfusion. In the I/R + AMD group, AMD reduced TNF increase to 44 pg/ml. The C and C + AMD groups showed no differences in TNF values during the 6 h of observation. We conclude that protein synthesis and TNF generation are at least partially involved in I/R-induced changes in microvascular transport.To better understand the mechanisms of ischemia-reperfusion (I/R) injury, we tested the hypothesis that protein synthesis is involved in the production of tumor necrosis factor (TNF) and in the microvascular transport changes in I/R. To evaluate the hypothesis, we inhibited protein synthesis with topically applied actinomycin D (AMD), measured I/R-induced changes in microvascular transport, and bioassayed the venous plasma levels of TNF. The rat cremaster muscle I/R model consisted of 4 h of ischemia followed by 2 h of reperfusion. Changes in transport were determined by integrated optical intensity (IOI) using FITC-Dextran 150 as tracer. Animals were separated into four groups: 1) control (C), 2) control treated with AMD (C + AMD), 3) I/R, and 4) I/R treated with AMD (I/R + AMD). The mean (±SE) maximal IOI in C and C + AMD were 3.0 ± 1.0 and 3.7 ± 0.7 units, respectively. I/R elevated mean maximal IOI to 21.8 ± 1.9 units ( P < 0.05 vs. C, C + AMD, I/R + AMD). Treatment with AMD reduced the I/R-induced mean maximal IOI to 9.7 ± 2.0 units ( P< 0.05 vs. I/R). In I/R group, plasma TNF levels increased (relative to preischemia baseline) immediately after the release of the vascular occlusion to 250 pg/ml and reached a peak value of 342 pg/ml at 60 min of reperfusion. In the I/R + AMD group, AMD reduced TNF increase to 44 pg/ml. The C and C + AMD groups showed no differences in TNF values during the 6 h of observation. We conclude that protein synthesis and TNF generation are at least partially involved in I/R-induced changes in microvascular transport.

Can nonpenetrating vascular closure staples and hepatocyte growth factor prevent intimal hyperplasia following ePTFE grafting of the carotid artery in rabbits

Abstract.Abstract.Purpose: To evaluate whether nonpenetrating vascular closure staples (VCS) and hepatocyte growth factor (HGF) can effectively prevent anastomotic intimal hyperplasia.Methods: An expanded polytetrafluoroethylene graft, 2 mm in diameter, was implanted in the common carotid artery of rabbits divided into three experimental groups. In the control group, distal anastomosis was performed with interrupted suturing; in the VCS group, clips were applied along the lateral suture line after the placement of stay sutures; and in the VCS + HGF group, the same anastomotic technique was performed as in the VCS group, followed by the administration of the HGF for 4 days.Results: The time taken to complete the anastomosis was significantly less in both the VCS groups than in the control group (P < 0.0001). On postoperative day (POD) 28, the patency rate was significantly lower (P < 0.05) in the VCS group (42.9%) than in the control group (100%), but the rate in the VCS + HGF group (100%) was the same as that in the control group. Intimal thickness was significantly less in the control group than in either the VCS or VCS + HGF groups (P < 0.05). The percentage of area stenosis was significantly less (P < 0.01) in the control group than in the VCS group.Conclusion: The VCS clip failed to suppress intimal thickness or reduce the percentage of stenosis at the anastomotic site.

Experimental and Clinical Studies Investigating the Efficacy of Distal Anastomosis with Patch Plasty in Bypass Operations with Expanded Polytetrafluoroethylene Grafts

Abstract.Purpose: We investigated the efficiency of distal anastomosis with patch plasty (DAPP), both experimentally and clinically. Methods: In our experimental study, dogs were divided into two groups: a control group in which anastomosis was performed without DAPP (n = 7), and a DAPP group in which DAPP was performed at the distal anastomosis (n = 7). In our clinical study, 169 femoropopliteal bypasses were divided into three groups and analyzed. In one group, the saphenous vein was used (SVG group, n = 65); in one group, an expanded polytetrafluoroethylene (ePTFE) graft was used without DAPP (ePTFE group, n = 64); and in one group, an ePTFE graft was used with DAPP (DAPP group, n = 40). Results: In the experimental study, the ratio between the area of thrombus adherence and the entire area of the intraluminal surface of the graft, defined as the thrombus covering ratio, was 48.9% in the control group and 30.2% in the DAPP group. The ratio in the DAPP group was significantly lower than that in the control group. In the clinical study, although there were no significant differences among the three groups in cumulative patency rates of the femoral above-knee popliteal arterial bypasses, the patency in the DAPP group was excellent. The cumulative patency rates of the femoral below-knee popliteal arterial bypasses in the ePTFE group were significantly lower than those in the other two groups. Conclusion: There results suggest that the addition of DAPP may achieve excellent graft patency.