Kazuomi Iwasa

Molecular and biophysical properties of voltage-gated Na+ channels in murine vas deferens

The biological and molecular properties of tetrodotoxin (TTX)-sensitive voltage-gated Na(+) currents (I(Na)) in murine vas deferens myocytes were investigated using patch-clamp techniques and molecular biological analyses. In whole-cell configuration, a fast, transient inward current was evoked in the presence of Cd(2+), and was abolished by TTX (K(d) = 11.2 nM), mibefradil (K(d) = 3.3 microM), and external replacement of Na(+) with monovalent cations (TEA(+), Tris(+), and NMDG(+)). The fast transient inward current was enhanced by veratridine, an activator of voltage-gated Na(+) channels, suggesting that the fast transient inward current was a TTX-sensitive I(Na). The values for half-maximal (V(half)) inactivation and activation of I(Na) were -46.3 mV and -26.0 mV, respectively. RT-PCR analysis revealed the expression of Scn1a, 2a, and 8a transcripts. The Scn8a transcript and the alpha-subunit protein of Na(V)1.6 were detected in smooth muscle layers. Using Na(V)1.6-null mice (Na(V)1.6(-/-)) lacking the expression of the Na(+) channel gene, Scn8a, I(Na) were not detected in dispersed smooth muscle cells from the vas deferens, while TTX-sensitive I(Na) were recorded in their wild-type (Na(V)1.6(+/+)) littermates. This study demonstrates that the molecular identity of the voltage-gated Na(+) channels responsible for the TTX-sensitive I(Na) in murine vas deferens myocytes is primarily Na(V)1.6.

Reduced proliferation of aged human vascular smooth muscle cells--role of oxygen-derived free radicals and BubR1 expression.

BACKGROUND Aging is a risk factor for atherosclerosis. Recent studies suggest cell cycle events as well as reactive oxygen species (ROS) contribute to vascular cell dysfunction associated with aging. Mice expressing low levels of the spindle assembly checkpoint protein BubR1 develop aging-associated vascular changes at a young age, including decreased smooth muscle cells and increased reactive oxygen species (ROS) production. This study was designed to determine the effect of aging and production of oxygen-derived free radicals on expression of BubR1. MATERIALS AND METHODS To assess cell proliferation capacity, human aortic smooth muscle cells (hAoSMC) derived from a young group (17-30 y) or an aged group (57-62 y) were cultured, and cell numbers were directly counted in using a Neubauer chamber. RT-PCR assay was used to evaluate BubR1 expression in cultured hAoSMC stimulated with Angiotensin II or H(2)O(2). RESULTS No significant difference in BubR1 expression or hAoSMC proliferative ability was demonstrated at passage 5, but both were significantly decreased at passage 8 in the aged hAoSMC. Angiotensin II and H(2)O(2) up-regulated BubR1 expression in young hAoSMC, and the up-regulation was abrogated by a p38 MAPK inhibitor or an inhibitor of the NADH/NADPH oxidase. siRNA against BubR1 reduced proliferative activity and increased ROS production in hAoSMC. CONCLUSIONS These findings demonstrate BubR1 mRNA expression decreases along with proliferation in aged hAoSMC. Aging-related loss of BubR1 and subsequent impairment of reactivity to ROS may explain reduced proliferative capacity of aged smooth muscle cells.

Strategy of Revascularization for Critical Limb Ischemia Due to Infragenicular Lesions—Which Should Be Selected Firstly, Bypass Surgery or Endovascular Therapy?

BACKGROUND AND OBJECTIVES In patients with peripheral arterial diseases (PADs) due to infra-popliteal (below the knee; BTK) lesions, we often encounter situations requiring the immediate selection of either of two revascularization methods, namely bypass surgery or endovascular therapy (EVT). However, the question of whether endovascular or surgical revascularization should be performed initially for critical limb ischemia (CLI) patients with BTK lesions has not been clarified. To assess the efficacy and durability of EVT or bypass as a first approach, we evaluated the short- and mid-term outcomes of the first revascularizations achieved using EVT (EVT First Group; EVT-first) compared with bypass (Bypass First Group; Bypass-first). To verify the validity of each initial revascularization, we explored factors influencing overall survival (OS) rates using multivariate analyses. METHODS A total of 169 consecutive BTK revascularization procedures (150 patients) for CLI conducted at our facility between November 2006 and July 2012 were analyzed. Patients undergoing revascularization were divided into two groups (EVT-first or Bypass-first), with 102 patients undergoing endovascular therapy first (EVT-first) and 51 undergoing bypass surgery first (Bypass-first). No statistically significant differences were noted between the two groups with respect to preoperative background including age, gender, and cardiovascular risk factors (hypertension, diabetes, hyperlipidemia, coronary arterial disease (CAD), chronic heart failure (CHF), cerebrovascular disease, and hemodialysis). Technical success was defined as a single straight-line flow to the ankle after completion angiography of the first revascularization method. Hemodynamic success was defined as a postoperative skin perfusion pressure of the foot exceeding 40 mmHg. RESULTS The average age of patients was 76.0 years (range, 46-98 years; 65 men and 37 women) and 72.3 years (range, 43-93 years; 35 men and 13 women) in the EVT-first and Bypass-first groups, respectively. Patient follow-up ranged from 1 to 50 months (mean, 15 months). Respective technical and hemodynamic success rates were 96.2% and 66.7% for EVT-first and 100% and 94% for Bypass-first, respectively. Treatment was required an average of 1.5 times for EVT-first and 1.2 times for Bypass-first. Respective rates for other factors examined in the EVT-first and the Bypass-first groups were: major amputation rates 30 days post-procedure, 5.9%, and 3.9%; mortality rates 30 days post-procedure, 3.9%, and 0%; one-year AFS rates, 71.7%, and 79.5%; OS rates, 73.5% and 83.9%; and limb salvage rates, 88.8%, and 91.0%. Multivariate-analysis of all subjects in the two groups revealed that the OS rates were affected by four risk factors as follows: (1) age greater than 80 years, (2) CAD, (3) CHF, and (4) a non-ambulatory limb. CONCLUSION For patients with CLI due to BTK lesions and whose saphenous veins are in poor condition or are in poor general condition having two or more of the four severe risk factors, the EVT-First procedure is effective and provides durable results. Overall survival in patients with CLI due to BTK lesions is worse when patients have more than two severe risk factors, which is non-ambulatory limb, aged less than 81 years, with CAD or with CHF. (This article is a translation of Jpn J Vasc Surg 2014; 23: 766-773.).

Successful Percutaneous Coil Embolization of a Ruptured Internal Iliac Artery Aneurysm Remnant after Abdominal Aortic Aneurysm Repair via the Deep Iliac Circumflex Artery.

Here, we describe a case of an 83-year-old man treated with percutaneous IIA coil embolization for an enlarging remnant IIA aneurysm. CT scans revealed a contained rupture and persistent flow in the right IIA with the enlargement. We selected percutaneous embolization via the deep iliac circumflex artery, that was communicating with the superior gluteal artery and the IIA. Coil embolization of the arteries supplying the IIA aneurysm was successfully performed with 12 embolization coils placed in the IIA and its branches. The absence of blood flow and shrinkage of the aneurysm were confirmed by CT three months after embolization.

Clinical Results of Endovascular Abdominal Aortic Aneurysm Repair in Patients with Renal Insufficiency without Hemodialysis.

OBJECTIVE Chronic renal insufficiency may be a relative contraindication to endovascular aneurysm repair (EVAR) for the use of contrast enhanced mediums. It is thought that more contrast enhanced media are needed in patients who are not anatomically suitable for EVAR, because of procedural difficulties. We reviewed a 2 year EVAR experience at our institution to determine whether the procedure and use of contrast enhanced mediums has any deleterious effect on renal function in patients with pre-existing chronic renal insufficiency. MATERIALS AND METHODS EVAR was performed in 46 patients with pre-existing chronic renal insufficiency without hemodialysis. Patients were retrospectively assigned to two groups on the basis of their preoperative creatinine clearance levels. Furthermore, patients were assigned to two other groups on the basis of anatomical suitability for EVAR. The absolute change in the serum creatinine (Cr) level was reviewed in the each renal insufficiency group between the preoperative and post-operative time periods. RESULTS No increase in the serum Cr level was noted, and no patient required temporary or permanent hemodialysis, in any of the groups. CONCLUSIONS EVAR with contrast agents can be accomplished in patients with chronic renal insufficiency without hemodialysis; therefore,elevated Cr levels maynot be a contraindication in EVAR.

Successful treatment of a visceral artery aneurysm with a celiacomesenteric trunk: report of a case.

A celiacomesenteric trunk is an anomaly in which the celiac and superior mesenteric arteries have a common origin from the aorta. This structure accounts for less than 1% of all visceral artery anomalies, and is estimated to have an incidence of 0.25%. Aneurysms involving a celiacomesenteric trunk are exceptionally rare. We herein report our treatment modality for an 82-year-old man with a visceral artery aneurysm involving a celiacomesenteric trunk. The aneurysm was resected, and the superior mesenteric, splenic, and common hepatic arteries were successfully reconstructed.

Evaluation of the Paramalleolar Bypass for Critical Limb Ischemia Patients on Hemodialysis with Diabetes Mellitus and Chronic Renal Failure

OBJECTIVE To assess the influence of diabetes mellitus (DM) and end-stage renal failure on hemodialysis (HD) on the healing time of tissue lesions and blood flow to the foot following a paramalleolar bypass in patients with critical limb ischemia (CLI). METHODS Consecutive patients with CLI and tissue loss (24 limbs) were followed up retrospectively after paramalleolar bypass, and the healing time of tissue lesions, graft patency, limb salvage and survival rates were analyzed. The blood flow to the foot was assessed by skin perfusion pressure (SPP) pre- and postoperatively. The delta SPP was calculated as the difference between the SPP before and after bypass. The patients were divided into 3 groups: diabetic (DM, n = 9); diabetic and end-stage renal failure on hemodialysis (HD, n = 10); or neither (n = 5). RESULTS A total of 15 dorsal and 9 plantar artery bypasses were performed. The median follow-up was 7.3 months (range, 1-18 months). No patients required major amputations, and all tissue lesions healed. The mean duration to complete tissue healing of the DM, HD and neither groups was 2.2, 2.5 and 1.2 months, respectively, was and these were not statistically significant. A significant improvement in the delta SPP after paramalleolar bypass was observed in the neither group compared with both the DM and HD groups. CONCLUSION Blood flow to the foot was not sufficiently improved in CLI patients with DM and HD, despite paramalleolar bypass. This may be the cause of the prolonged tissue healing duration of CLI patients with DM and HD. (English Translation of Jpn J Vasc Surg 2012; 21: 91-95).

Risk factors for wound complications and 30-day mortality after major lower limb amputations in patients with peripheral arterial disease

Purpose Risk factors for wound complications or 30-day mortality after major amputation in patients with peripheral arterial disease remain unclear. We investigated the outcomes of major amputation in patients with peripheral arterial disease. Methods Patients who underwent major amputation from 2008 to 2015 were retrospectively analyzed. The main outcome measures were risk factors for wound complications and 30-day mortality after major lower limb amputations. Major amputation was defined as above-knee amputation or below-knee amputation. Wound complications were defined as surgical site infection or wound dehiscence. Results In total, 106 consecutive patients underwent major amputation. The average age was 77.3 ± 11.2 years, 67.9% of patients had diabetes mellitus and 35.8% were undergoing hemodialysis. Patients who underwent primary amputation constituted 61.9% of the cohort, and the proportions of above-knee amputation and below-knee amputation were 66.9% and 33.1%, respectively. The wound complication rate was 13.3% overall, 10.3% in above-knee amputation, and 19.5% in below-knee amputation. Multivariate analysis showed that the risk factors for wound complications were female sex (hazard ratio, 4.66; 95% confidence interval, 1.40–17.3; P = 0.01) and below-knee amputation (hazard ratio, 4.36; 95% confidence interval, 1.20–17.6; P = 0.03). The 30-day mortality rate was 7.6%, pneumonia comprised the most frequent cause of 30-day mortality, followed by sepsis and cardiac death. Multivariate analysis showed that a low serum albumin concentration (hazard ratio, 3.87; 95% confidence interval, 1.12–16.3; P = 0.03) was a risk factor for 30-day mortality. Conclusions Female sex and below-knee amputation were risk factors for wound complications. A low serum albumin concentration was a risk factor for 30-day mortality after major amputation in Japanese patients with peripheral arterial disease.

Long-Term Results of a Hybrid Revascularization Procedure for Peripheral Arterial Disease.

OBJECTIVE To evaluate the efficacy of hybrid procedure for peripheral arterial disease (PAD), we compared the cases treated using the hybrid procedure with those treated using open revascularization (bypass alone) in our facilities. MATERIALS AND METHODS We retrospectively reviewed 204 patients who underwent revascularization for PAD between 2007 and 2013. We divided the patients into two groups based on the type of procedure. Group 1 included patients who underwent the hybrid procedure, that is, doing endovascular therapy (EVT) either femoral or iliac resion and added the bypass procedure (infragenicular vein bypass) to the below knee artery, and group 2 included patients who underwent only bypass procedure (used autovein), that is, central anastomotic region was femoral artery region and peripheral anastomotic region was below knee artery. We evaluated various factors between the two groups, including the primary patency rate, secondary patency rate, amputation-free survival rate, and determined the efficacy of the hybrid procedure for PAD. RESULTS In the patients characteristics, there was significant difference between the two groups in the cases with cerebrovascular disease, only (p = 0.03). There were no significant differences in the primary or secondary patency rates, and the amputation-free survival rate. CONCLUSIONS Primary patency rate, secondary patency rate, and amputation-free survival rate of the hybrid procedure were comparable to those of bypass (alone) procedure. The hybrid procedure is therefore an acceptable strategy for patients with PAD.

Molecular analysis of ATP-sensitive K+ channel subunits expressed in mouse vas deferens myocytes

ATP‐sensitive K+ (KATP) channels, which are composed of KIR6.x associated with sulphonylurea receptor (SUR) subunits, have been detected in native smooth muscle cells, but it is currently not known which of these is expressed in mouse vas deferens myocytes.