ABSTRACT: We previously reported that, in a short-term thoracic inferior vena cava (IVC) replacement, a highporosity expanded polytetrafluoroethylene
(ePTFE) graft (fibril length 60μm) performed well without altering the short-term patency, and that the healing of the high-porosity
ePTFE graft was accelerated by an omentum wrap. The purpose of this study was to examine the long-term performance of the
high-porosity ePTFE graft with or without an omentum wrap. Eighteen grafts were placed as a thoracic IVC replacement in dogs.
Nine of the grafts were wrapped in an omental pedicle flap while the other 9 were not. At 1 month and 6 months, the grafts
were harvested and examined for a pathological analysis. During the observation period, one dog died of a viral infection,
while the other 17 dogs survived. At 1 month and 6 months, the patency rates of the 17 grafts were 100% regardless of the
presence or absence of an omentum wrap. The healing of the grafts without omentum wrap was incomplete 6 months after implantation;
granulation tissue was present in the center of the pseudointima. The grafts healed completely by the addition of an omentum
wrap. Our data suggest that, with an omentum wrap, the high-porosity ePTFE graft is fully expected to show a good long-term
Key WordsHigh-porosity polytetrafluoroethylene graft–Omentum wrap–Thoracic inferior vena cava reconstruction
Surgery Today 04/2012; 30(7):631-635. · 1.22 Impact Factor
ABSTRACT: We comparatively evaluated the protective effect of the immunophilin ligands cyclosporine A (INN: ciclosporin), FK506, and rapamycin on the spinal cord in a rabbit model of transient ischemia. Both cyclosporine A and FK506 inhibit calcineurin, whereas rapamycin does not.
Thirty-six male New Zealand White rabbits were divided into the following 6 groups: group C, 15 minutes of spinal cord ischemia; group FK, FK506 (1 mg/kg) administered 30 minutes before ischemia; group CsA, cyclosporine A (30 mg/kg) administered 30 minutes before ischemia; group CsA-C, chronic administration of cyclosporine A (20 mg/kg) for 9 days before ischemia; group R, rapamycin (1 mg/kg) administered 30 minutes before ischemia; and group R+FK, rapamycin (1 mg/kg) administered 20 minutes before FK506 pretreatment (1 mg/kg). Group CsA-C was added because the drug does not readily cross the blood-brain barrier. Neurologic function was evaluated by Johnson's 5-point scale at 8, 24, and 48 hours after ischemia, and histopathology was assessed 48 hours after ischemia.
At 24 and 48 hours after ischemia, the Johnson score was better in groups FK (4.0 +/- 1.1), R+FK (3 +/- 1.1), and CsA-C (2.7 +/- 1.2) than in group C (0.8 +/- 1.2). Numbers of morphologically intact anterior horn cells were higher in groups FK (31.3 +/- 9.9), R+FK (23.2 +/- 4.5), and CsA-C (18.3 +/- 6.8) than in group C (6.3 +/- 4.3).
FK506 and chronic administration of cyclosporine A, but not rapamycin, protect the spinal cord from transient ischemia. Although these results are compatible with inhibition of calcineurin in the mechanism of neuroprotective action of these drugs, other effects through different pathways cannot be excluded before further study.
Journal of Thoracic and Cardiovascular Surgery 02/2005; 129(1):123-8. · 3.41 Impact Factor
ABSTRACT: The purpose of this study was to analyze apoptosis in the vessel wall after stent implantation in the canine portal vein and also to investigate the expression of the p21 cyclin-dependent kinase inhibitor, which may regulate cellular proliferation after vascular injury. Uninjured, control veins had few detectable TUNEL-positive cells in the intima and media (0.829 +/- 0.413%). At 4 weeks after stent implantation, TUNEL-positive cells significantly increased to 50.5 +/- 4.639%. These cells were predominantly located around the stent struts, and appeared to be smooth muscle cells morphologically. At 12 weeks, 44.7 +/- 6.178% of the intimal and medial cells were still TUNEL positive, and there was no significant difference between 4 and 12 weeks. P21 was not detected in uninjured, normal veins. At 4 and 12 weeks after stent implantation, positive p21 immunostaining was sparsely expressed in the intima and media adjacent to the stent struts. Thus, stent implantation induced a prolonged apoptotic response and increased expression of p21 in the portal venous system. This prolonged apoptotic response, possibly regulated by p21, may have a significant role in modulating the cellularity of intimal formation.
Annals of Vascular Surgery 08/2002; 16(4):456-61. · 1.03 Impact Factor
ABSTRACT: This study was designed to examine the short-term performance of Gianturco stents placed in the venous system, in comparison
with that of stents placed in the arterial system. Single-bodied modified Gianturco stents were surgically placed in six dogs
(group 1), while in another six dogs, only exposure of the vessels was performed (group 2). Segments with an outer diameter
0.9 times smaller than those of the stents were targeted in the infrarenal inferior vena cava (IVC), the portal vein (PV),
and the infrarenal abdominal aorta (AA). The animals were killed 4 weeks postoperatively for pathological analysis. All the
segments were patent in both groups. Although the stents placed in the infrarenal IVC and PV were completely covered with
neointima, those placed in the infrarenal AA were only partially covered. Furthermore, the venous stents were deeply embedded
in the media, while the aortic stents remained in the intima. Medial hyperplasia occurred in the venous stents, while intimal
hyperplasia occurred in the aortic stents. In conclusion, Gianturco stents placed in the IVC and PV performed better in the
short term than the stents placed in the AA.
Key wordsGianturco stent–venous stenting–intimal hyperplasia–medial hyperplasia–NIH image
Surgery Today 04/1998; 28(4):396-400. · 1.22 Impact Factor
ABSTRACT: The purpose of this study was to examine the short- and long-term performance of conventional polytetrafluoroethylene (PTFE)
grafts for portal vein reconstruction. The grafts were placed as a portal vein replacement in 11 mongrel dogs. At 1 month
and 6 months, the grafts were then retrieved and examined for patency, while also undergoing a pathological analysis. During
the observation period (at 55 days), one dog died of an unknown cause with a patent graft. The patency rates of the other
10 grafts were 83% (5/6) at 1 month and 100% (4/4) at 6 months. However, the neointima formation was incomplete even 6 months
after implantation. In conclusion, although conventional PTFE grafts may be used as a synthetic alternative to autogenous
vein grafts, every effort should be made to use autogenous vein grafts before considering conventional PTFE grafts.
Key Wordsconventional polytetrafluoroethylene grafts–portal vein reconstruction
Surgery Today 04/1998; 28(4):391-395. · 1.22 Impact Factor
ABSTRACT: We examined the patency and healing of a highporosity expanded polytetrafluoroethylene (ePTFE) graft implanted as an interposition
graft in the thoracic inferior vena cava (IVC) and wrapped in an omental pedicle flap. High-porosity ePTFE grafts of 60 μ
fibril length, with an internal diameter of 10 mm and a length of 4 cm, were implanted in 12 mongrel dogs. In 6 dogs, the
grafts were wrapped in omental pedicle flap, and in the remaining 6 the grafts were unwrapped. The animals were killed 4 weeks
after the replacement and the grafts were removed for examination. Patency of the graft in both groups was 100%; however,
the thrombusfree area in the omentum-wrapped group was significantly larger (P<0.05) than that in the unwrapped group. Light microscopy revealed the marked infiltration of cells and capillaries within
the graft interstices in the omentum-wrapped group. These findings suggest that encapsulation of the highporosity ePTFE graft
is promoted by an omental pedicle flap.
Surgery Today 08/1997; 27(9):846-850. · 1.22 Impact Factor
ABSTRACT: This study was designed to reexamine the healing process of expanded polytetrafluoroethylene (EPTFE) grafts with standard
porosity (30μm) and high porosity (60μm) in portal vein replacement, and to evaluate the effect of an omentum wrap, which
has certain functions that promote healing, on graft healing. These grafts, either wrapped by the omentum or not, were placed
as portal vein replacements in 24 mongrel dogs. After 1 month, the grafts were retrieved and examined for patency, thrombus-free
areas, thickness of the pseudointima, and the total number of cells growing into the graft wall. There were no statistical
differences in the patency rates. The high-porosity grafts had a significantly larger thrombus-free area, a thicker pseudointima,
and a larger growth of cells than the standard-porosity grafts. The omentum wrap significantly increased the thrombus-free
area and stimulated a larger growth of cells in both grafts. The high-porosity grafts plus omentum demonstrated a thrombus-free
area of 82.2%vs 27.3% in the standard-porosity grafts. In addition, the migration of fibroblasts and macrophages was most evident in the
high-porosity grafts wrapped by the omentum. In conclusion, graft healing enhancement was observed in the high-porosity EPTFE
grafts wrapped by the omentum. It is thus suggested that transmural cellular migration plays an important role in the process
of graft healing.
Surgery Today 01/1997; 27(2):149-153. · 1.22 Impact Factor
ABSTRACT: The purpose of this study was to examine the intermediate (6-month) patency and healing characteristics of high-porosity expanded
polytetrafluoroethylene (ePTFE) grafts with and without omentum wrap in a dog portal vein replacement model, compared with
short-term (1-month) results. The grafts, either wrapped by omentum or not, were placed as portal vein replacements in 22
mongrel dogs. After 1 and 6 months, the grafts were retrieved and examined for patency and subjected to pathology study. Although
the short-term patency rate in all grafts was 100%, regardless of the presence or absence of omentum wrap, the intermediate
patency of high-porosity ePTFE without omentum wrap was very poor (20%). On the other hand, high-porosity ePTFE with omentum
wrap had an intermediate patency rate of 100%. At 6 months, the high-porosity ePTFE grafts with omentum wrap were completely
healed. The pseudointima was entirely replaced by thin fibrous tissue, with complete endothelial-like cell coverage throughout
the graft. This result suggests that high-porosity ePTFE with omentum wrap could be a suitable prosthetic alternative to autogenous
vein graft in portal vein reconstruction.
Journal of Hepato-Biliary-Pancreatic Surgery 01/1996; 3(4):474-479. · 1.60 Impact Factor