Reverse endoventricular artificial obturator in tricuspid valve position. Experimental feasibility research study

The concept of vena contracta space reduction in tricuspid valve position was tested in an animal model. Feasibility of specific artificial obturator body (REMOT) fixed to the right ventricular apex and interacting with tricuspid valve leaflets was evaluated in three different animal studies. Catheter-based technique was used in three series of experiment in 7 sheep. First acute study was designed for evaluation if the screwing mode of guide wire anchoring to the right ventricular apex is feasible for the whole REMOT body fixing. Longer study was aimed to evaluate stability of the REMOT body in desired position when fixing the screwing wire on its both ends (to the right ventricular apex and to the skin in the neck area). X-ray methods and various morphological methods were used. The third acute study was intended to the REMOT body deployment without any fixing wire. In all of 7 sheep the REMOT was successfully inserted into the right heart cavities and then fixed to the right ventricular apex area. When the REMOT was left in situ more than 6 months it was stable, induced adhesion to the tricuspid valve leaflet and was associated with a specific cell invasion. Releasing of the REMOT from the guiding tools was also successfully verified. Deployment of the obturator body in the aim to reduce the tricuspid valve orifice is feasible and well tolerated in the short and longer term animal model. Specific cell colonization including neovascularization of the obturator body was observed.

A new cone-shaped aortic valve prosthesis for orthotopic position: an experimental study in Swine

The aim of this experimental study was to evaluate a newly designed cone-shaped aortic valve prosthesis (CAVP) for one-step transcatheter placement in an orthotopic position. The study was conducted in 15 swine using either the transcarotid (11 animals) or the transfemoral (4 animals) artery approach. A 12- or 13-Fr sheath was inserted via arterial cutdown. The CAVP was deployed under fluoroscopic control and its struts, by design, induced significant native valve insufficiency. CAVP function was evaluated by aortography and aortic pressure curve tracing. In 11 of 15 swine the CAVP was properly deployed and functioned well throughout the scheduled period of 2-3 h. In three swine the CAVPs were placed lower than intended, however, they were functional even in the left ventricular outflow tract position. One swine expired due to inadvertent low CAVP placement that caused both aortic regurgitation and immobilization of the anterior mitral valve leaflet by the valve struts. We conclude that this design of CAVP is relatively easy to deploy, works well throughout a short time period (2-3 h), and, moreover, seems to be reliable even in a lower-than-orthotopic position (e.g., infra-annulary space). Longer-term studies are needed for its further evaluation.

Creation of a gastroenteric anastomosis with endoscopy and percutaneous gastrostomy in pigs

The authors have previously shown in pigs an immediate transgastric technique for stapling the stomach and jejunum to allow a functioning gastroenteric anastomosis (GEA) with use of balloons and stent placement. The aim of this approach in six pigs was to replicate this procedure by using a flexible endoscopic technique. All pigs had GEAs that were well attached and fully patent.

Small intestinal submucosa sandwich Zilver stent-grafts for TIPS: experimental pilot study in swine

The aim of this study was the evaluation of preliminary suitability of the piglet small intestinal submucosa (SIS) sandwich Zilver endograft for experimental transjugular intrahepatic portosystemic shunt (TIPS) creation. TIPS was created in six swine. The five surviving animals underwent the follow-up portogram and were sacrificed at four weeks after TIPS creation. Gross and histologic examination was performed in all animals. TIPS creation was successful in all animals. One animal died four days after TIPS creation. In the five surviving animals, one shunt was occluded and four shunts were stenosed on the follow-up portogram. The mean percentage narrowing of the most advanced stenoses was 72% (range, 60%-100%). The most advanced stenosis was located in the parenchymal tract in three shunts and in the hepatic vein portion in one shunt. Gross and histologic examination showed abundant neointimal formation composed mainly of fibroblasts leading to the significant shunt stenoses. The piglet SIS sandwich Zilver stent-graft was found to offer only limited TIPS patency and should not be used for the definitive long-term TIPS study.

Percutaneous vein occlusion with small intestinal submucosa: an experimental pilot study in Swine and sheep

PURPOSE

The objective of this study was to investigate the feasibility, outcomes, and amount of small intestinal submucosa (SIS) material needed for embolization of jugular vein (JV) in a swine and sheep model. Our hypothesis was that SIS would cause vein occlusion.

MATERIALS AND METHODS

The external JVs (EJV) in swine (n = 6) and JVs in sheep (n = 6) were occluded with SIS fan-folded compressed strips. After percutaneous puncture of the peripheral portion of the EJV or JV, a TIPS set was used to exit their lumen centrally through the skin. The SIS strips were delivered into the isolated venous segment with a pull-through technique via a 10-Fr sheath. Follow-up venograms were done immediately after placement and at the time of sacrifice at 1 or 3 months. Gross examinations focused on the EJV or JV and their surrounding structures. Specimens were evaluated by histology.

RESULTS

SIS strip(s) placement was successful in all cases, with immediate vein occlusion seen in 23 of 24 veins (95.8%). All EJVs treated with two strips and all JVs treated with three or four strips remained closed on 1- and 3-month follow-up venograms. Two EJVs treated with one strip and one JV treated with two strips were partially patent on venograms at 1 and 3 months. There has been one skin inflammatory reaction. Necropsies revealed excluded EJV or JV segments with SIS incorporation into the vein wall. Histology demonstrated various stages of SIS remodeling with fibrocytes, fibroblasts, endothelial cells, capillaries, and inflammatory cells.

CONCLUSION

We conclude that EJV and JV ablation with SIS strips using percutaneous exit catheterization is feasible and effective in animal models. Further exploration of SIS as vein ablation material is recommended.

Estimation of Trapped Thrombus Volumes in Retrievable Inferior Vena Cava Filters: A Visual Scale

PURPOSE

To establish a visual, objective scale for estimating trapped thrombus volumes in five types of retrievable inferior vena cava filters.

MATERIAL AND METHODS

Silicone-based radiopaque polymer volumes of 0.25, 0.5, 1.0, 1.5, 2.0, 3.0, and 4.0 mL were created. Both sphere and cone shapes were used. Polymer volumes were confirmed by means of the water displacement method. The volumes were then positioned to simulate trapped thrombus in five retrievable filters: Recovery and G2 (Bard Peripheral Vascular, Tempe, Ariz), Günther Tulip and Celect (Cook, Bloomington, Ind), and OptEase (Cordis Endovascular, Warren, NJ). Radiographs were obtained by using conventional parameters. Visual scales of thrombus volume were created for each filter type.

RESULTS

Visual scales for each retrievable filter type were created with simulated thrombi in typical trapping positions.

CONCLUSION

The authors developed a visual, objective scale for estimating trapped thrombus volume in five types of retrievable IVC filters. This could facilitate standardized reporting of thrombus volumes in studies of optional vena cava filters.

Percutaneous transcatheter one-step mechanical aortic disc valve prosthesis implantation: a preliminary feasibility study in swine

PURPOSE

To evaluate the feasibility of one-step implantation of a new type of stent-based mechanical aortic disc valve prosthesis (MADVP) above and across the native aortic valve and its short-term function in swine with both functional and dysfunctional native valves.

METHODS

The MADVP consisted of a folding disc valve made of silicone elastomer attached to either a nitinol Z-stent (Z model) or a nitinol cross-braided stent (SX model). Implantation of 10 MADVPs (6 Z and 4 SX models) was attempted in 10 swine: 4 (2 Z and 2 SX models) with a functional native valve and 6 (4 Z and 2 SX models) with aortic regurgitation induced either by intentional valve injury or by MADVP placement across the native valve. MADVP function was observed for up to 3 hr after implantation.

RESULTS

MADVP implantation was successful in 9 swine. One animal died of induced massive regurgitation prior to implantation. Four MADVPs implanted above functioning native valves exhibited good function. In 5 swine with regurgitation, MADVP implantation corrected the induced native valve dysfunction and the device's continuous good function was observed in 4 animals. One MADVP (SX model) placed across native valve gradually migrated into the left ventricle.

CONCLUSION

The tested MADVP can be implanted above and across the native valve in a one-step procedure and can replace the function of the regurgitating native valve. Further technical development and testing are warranted, preferably with a manufactured MADVP.

Prophylactic residual aneurysmal sac embolization with expandable hydrogel embolic devices for endoleak prevention: preliminary study in dogs

OBJECTIVE

To explore the feasibility and efficacy of residual aneurysmal sac (RAS) embolization with the expandable hydrogel embolic device (EHED) in prevention of endoleaks in a surgically created and endoluminally treated abdominal aortic aneurysm (AAA).

METHODS

In eight dogs, an AAA was created by means of side-to-side anastomosis between the infrarenal abdominal aorta and inferior vena cava (IVC) with ligation of the IVC above and below the anastomotic end, followed by deployment of an endograft with holes. The RAS was then embolized with the EHED. One animal was killed immediately after RAS embolization and one animal died 12 hr after the procedure. Follow-up aortograms were obtained in six animals after 1 day (1 animal), 2 weeks and 6 months (1 animal), and 8 weeks (4 animals).

RESULTS

Four animals had no endoleaks on the follow-up aortograms. The remaining two animals with incomplete RAS embolization had moderate type III endoleaks. Type I or II endoleaks were not seen in any animals. Complications included RAS wall penetration by the devices with platinum wires in two animals (nos. 1 and 2), device migration into an aortic circulation through the endograft holes in two animals (nos. 2 and 3) or through distal interstices between the aortic wall and endograft in one animal (no. 8), aortic occlusion in three animals (nos. 3, 7, and 8), and RAS rupture in one animal (no. 7). Histologic examination showed expanded hydrogels occupying the RAS with associated mature or immature organized thrombus, fibrinous thrombus, or degenerate blood cells.

CONCLUSION

RAS embolization was feasible with the EHED, although additional modifications to the device are required to avoid complications. Angiographic and histologic results suggested that RAS embolization with the EHED may help in the prevention of endoleaks.

Long-term optional retrievability of a new inferior vena cava filter in an ovine model

Long-term retrievability of a new optional retrieval inferior vena cava (IVC) filter composed of a modified square stent and a modified Günther Tulip filter was tested in eight sheep. Eleven filters were placed into the IVC and eight were successfully retrieved 3-5 months after implantation. Incorporation of the filter struts into the IVC wall prevented its retrieval in three sheep at 3, 4, and 5 months after placement.

A flexible stent with small intestinal submucosa covering for direct intrahepatic portocaval shunt: experimental pilot study in swine

The suitability of the flexible sandwich Zilver stent-graft (SZSG) with a biologically active tissue layer (small intestinal submucosa) for creation of the intravascular ultrasound (IVUS)-guided direct intrahepatic portocaval shunt (DIPS) was explored in six young swine in a search for a flexible system to replace the rigid polytetrafluoroethylene (PTFE) stent originally used by this group with limited success. The portal vein was punctured from the inferior vena cava through the caudate lobe of the liver using IVUS guidance. After balloon dilation of the puncture tract, DIPS was successfully created in all animals with use of an SZSG 9 mm in diameter and 6 cm or 8 cm long. Only one DIPS remained well patent at 14 days when the animal had to be killed because of encephalopathy. DIPS in the other five animals were found to be either severely stenosed (3 animals) or occluded (2 animals) at 4 weeks due to accelerated formation of neointimal hyperplasia (NIH) in the liver parenchymal portion of the shunt and superimposed thrombosis. The lack of high pressure in the portal system contributed to early endograft closure. The flexible stent and the covering fail badly. The reason for this could be due to either component. More work is required to find a reliable flexible system with long-term patency. Exploration of the IVUS-guided direct extrahepatic portocaval shunt is suggested.

Percutaneous Transgastric Technique for Creating Gastroenteric Anastomoses in Swine

PURPOSE

To develop a percutaneous transgastric procedure for creating a stent-containing gastroenteric anastomosis (GEA).

MATERIALS AND METHODS

Acute experiments were performed on eight pigs. A 10-F gastroduodenostomy sheath was used to insert guide wires and targeting devices in the retrogastric jejunal loop; a 6.5-F sheathed trocar needle was then introduced through a second gastric sheath to puncture and catheterize the jejunum through the back of the stomach. Two special sliding anchor pairs were introduced through the catheter to "sandwich" the gastric sheath to the jejunal wall. The jejunum was catheterized a third time between the anchor sets to create a GEA tract for insertion of a stent. The animals were killed at various periods as long as 1 month after the experiments.

RESULTS

Snares were the most useful targeting devices for jejunal puncture. Single (n = 1) and double (n = 7) anchor-pair staples effectively prevented intraperitoneal leakage during and after insertion of 12-mm or 14-mm stents. Necropsy of six healthy animals at 5 days, 7 days, 14 days, and 4 weeks (n = 3) showed well-developed patent GEA anastomoses. There was one anesthetic death; one animal was killed at 4 days for obstructive ileus after a difficult transgastric jejunal catheterization.

CONCLUSIONS

A GEA can be fashioned through a percutaneous gastrostomy with stapling anchors. This technique may have clinical applications for managing gastric outlet obstruction.

Small Intestinal Submucosa Aneurysm Sac Embolization for Endoleak Prevention after Abdominal Aortic Aneurysm Endografting: A Pilot Study in Sheep

PURPOSE

To percutaneously create an improved abdominal aortic aneurysm model of endoleak after endograft placement and to explore efficacy of small intestinal submucosal embolization of the residual aneurysmal sac for prevention of endoleaks.

MATERIALS AND METHODS

Abdominal aortic aneurysm was created transluminally by over-dilation of a Palmaz stent in 12 sheep. Approximately 20% undersized endografts suspended between two stent-graft adapters were used to bridge the aneurysm in a manner that two lumbar pairs remained patent within the residual aneurysm sac. Size of the residual aneurysm sac was increased by placement of an undersized stent-graft consisting of damaged lyophilized small intestinal submucosal sheets sandwiched between two Zilver stents. In six sheep, residual aneurysm sacs were embolized by combining small intestinal submucosal sponge and small intestinal submucosal sheet pieces. The other six sheep served as the control group. Angiography performed immediately after the procedure was compared with follow-up angiography before the animals were killed at 1, 3, and 7 months. Gross and histologic examinations were also obtained.

RESULTS

Aortic ruptures (n = 3) and dissections (n = 2) during aneurysm creation responded well to endograft placement. Eleven endografts were placed successfully, one was misplaced. The mean diameter of aneurysmal sac was 16 mm in the study and 15.2 mm in the control group. In the study group, in four sheep, the sac and seven pairs of lumbar arteries were occluded by embolization and remained obstructed by organized thrombus during the entire study. There were no type II endoleaks. Four type III new endoleaks developed without antegrade filling of lumbar arteries. In the control group, five animals had type I and II endoleaks at the initial studies. Only one sheep exhibited completely organized thrombosis of the aneurysmal sac and without endoleaks. In the other four sheep with partially organized sac thrombosis, endoleaks were unchanged. One type III endoleak occurred in this group.

CONCLUSION

The combination of small intestinal submucosal sponge and small intestinal submucosal sheet pieces is a promising embolic material for occlusion of the residual sac after endovascular abdominal aortic aneurysm repair and for prevention of type II endoleaks.

Comparison of Small Intestinal Submucosa-Covered and Noncovered Nitinol Stents with PTFE Endografts in Injured Ovine Femoral Arteries: A Pilot Study

The purpose of this study was to compare performance of small intestinal submucosa (SIS)-covered endografts (SCEs) to polytetra-fluoroethylene (PTFE)-covered endografts (PCEs) and to bare nitinol stents (BSs) in injured sheep femoral artery (FA). Bare Zilver 6 mm X 40 mm nitinol stents (n = 6), Zilver stents covered with SIS (n = 6), and Palmaz stents 6 mm x 37 mm covered with PTFE (n = 6) were implanted in the balloon-injured FAs of nine female sheep. Follow-up arteriograms were obtained before animal sacrifice at 1, 3 and 6 months, with three animals at each time point. The FAs with the implanted device were explanted for histologic studies and morphologic measurements. Stent implantation was technically successful in all sheep. All BS and SCEs were patent at each time point. Five BSs and five SCEs exhibited formation of progressive eccentric intimal hyperplasia (IH) that was more advanced in SCE at 6 months. Cross-sectional area narrowing averaged 60% for BSs and 67% for SCEs. One BS, one SCE and two patent PCEs exhibited mild-to-moderate formation of concentric IH. Four PCS occluded one at 1 month, two at 3 months and one at 6 months. Performance of the devices placed into sheep FAs depended on their relation to the curving peri-articular portion of the FA during extremity flexion. BSs and SCEs placed in this portion exhibited progressive growth of eccentric IH while PCEs placed in this portion occluded.

A Canine Model for Studying Endoleak after Endovascular Aneurysm Repair

PURPOSE

The aim of this study was to create an animal model of endoleak after stent-graft placement for abdominal aortic aneurysm (AAA) in which a large aneurysmal sac would be preserved for the testing of techniques for its percutaneous occlusion.

MATERIALS AND METHODS

Infrarenal AAAs were created in nine dogs by anastomosis of an isolated segment of the inferior vena cava to the right side of the abdominal aorta in combination with a large anterior patch from the external jugular vein. One hour later, animals underwent percutaneous implantation of polytetrafluoroethylene-covered Z stent endografts with three 3-mm-diameter holes through the fabric. Aortograms were obtained before and after surgery, after endograft placement, and at the time of animal sacrifice at 1 week or 1, 2, 3, or 6 months. Pressures within the aorta and the aneurysm sac were recorded before animal sacrifice. Gross and histologic evaluations of the specimens were then carried out.

RESULTS

Immediately after endograft placement, all nine animals had artificial type III endoleaks with angiographic filling of lumbar arteries and veins. One animal died of surgical complications within 2 days of surgery and is not included in our data analysis. One aneurysm ruptured at 1 week. At completion of the study, six endografts were patent and two were occluded. The aneurysm sac had enlarged by approximately 50% in seven animals. At follow-up, type I endoleak was present in three animals, type II endoleak was present in three, and the artificial type III endoleak was present in all six animals with patent endografts. The pressure differential between aorta and aneurysm sac was 36 mm Hg, with a mean aortic pressure of 87 mm Hg +/- 13.3 and a mean aneurysmal sac pressure of 51 mm Hg +/- 28.1. The aneurysmal sac exhibited early thrombus formation at 1 week, which progressed to complete thrombosis in 1-6 months.

CONCLUSIONS

The model is technically feasible but would be useful in testing occlusive techniques for residual aneurysm sacs only in the acute phase after endograft placement. It would be not reliable for chronic evaluation because of rapidly progressive thrombosis in most aneurysm sacs and occasional complete thrombosis of the AAA and endograft.

Remodeling of suspended small intestinal submucosa venous valve: an experimental study in sheep to assess the host cells' origin

PURPOSE

To investigate the origin of host cells during remodeling of small intestinal submucosa (SIS) square stent-based bicuspid venous valves (VVs).

MATERIALS AND METHODS

Suspended VVs (SVVs) were developed by suspending VVs within bare square stents so the valve elements would not contact the vein wall after deployment. Eight SVVs were placed within the intrahepatic and infrahepatic inferior venae cavae (IVCs) of four adult female sheep. Eight standard VVs were implanted in the external jugular veins of these animals for comparison. At 5 weeks after placement, the devices were examined for stability and patency and the animals were killed. Gross, histologic, and scanning electron microscopic (SEM) examinations were performed.

RESULTS

Follow-up spot radiographs and venography showed no migration of the devices, venous occlusion, or thrombus formation. All SVVs were intact without contact with the IVC wall. Six VVs were competent and two were slightly tilted with some reflux. Histologic study showed remodeling of SVVs and VVs with newly formed collagen fibers; fibroblasts and inflammatory cells were found penetrating the SIS leaflets and endothelial cells on the surface. SIS neovascularization was also present. There was no difference regarding SIS remodeling between SVVs and the free part of VV leaflets. The VV leaflets' bases were thicker compared to their free parts (P <.01). SEM examination showed endothelial cells on both sides of the SVVs and VVs. Endothelialization of the SVV central leaflet surfaces and both surfaces of the VV leaflets was more complete than that of the peripheral surfaces of the SVV leaflets.

CONCLUSION

SIS-based valve remodeling occurs independently of vessel wall contact by recruitment of cells directly from the circulation.

Comparison of small intestinal submucosa-covered and noncovered nitinol stents in sheep iliac arteries: a pilot study

PURPOSE

To compare the biocompatibility and performance of nitinol endografts covered externally or internally with small intestinal submucosa (SIS) with bare nitinol stents in medium-sized arteries.

MATERIALS AND METHODS

Eighteen nitinol Zilver stents were used: six externally SIS-covered endografts (ECEs), six internally SIS-covered endografts (ICEs), and six bare stents (BSs). Devices were implanted in the balloon-injured external iliac arteries (EIAs) of nine female sheep via carotid approach. Arteriograms were obtained before and after implantation and before animal sacrifice at 1, 3, and 6 months. Histologic studies of explanted specimens were performed.

RESULTS

Implantation of all BSs, ECEs, and ICEs was successful, but slight luminal narrowing of 19% +/- 5.3% (range, 12%-28%) was seen in ICEs on postimplantation angiograms. At sacrifice, all six BSs and ECEs were patent, with BSs showing a mean angiographic luminal narrowing of 8.4% +/- 7.2% (range, 0%-18%) and ECEs showing a mean angiographic luminal narrowing of 16% +/- 7.5% (range, 6.5%-26%) as a result of neointimal hyperplasia. Four ICEs showed luminal narrowing of 21% +/- 17% (range, 0%-35%) as a result of marked neointimal hyperplasia and two were occluded, one at 3 months and the other at 6 months. ECEs and BSs showed approximately 80% lumen endothelialization at 1 month, which increased to 100% at 3 and 6 months. ICEs did not show complete endothelialization.

CONCLUSION

The BS had the least vessel wall reaction. ECEs exhibited early endothelialization with early mild to moderate wall reaction decreasing at the late study stages. ICEs showed extensive wall reaction, possibly as a result of technical problems with SIS attachment.

Percutaneous bioprosthetic venous valve: a long-term study in sheep

A long-term evaluation of a new percutaneously placed bioprosthetic, bicuspid venous valve (BVV) consisting of a square stent and small intestinal submucosa (SIS) covering was performed in 12 sheep. Of 26 BVVs placed into the jugular veins, 25 exhibited good valve function on immediate venography and 22 on venograms obtained before the sheep were killed. Gross and histologic examination results demonstrated incorporation of remodeled and endothelialized SIS BVVs into the vein wall. Slight to moderate leaflet thickening was found mostly at their bases. Percutaneously placed SIS BVV is a promising one-way, competent valve that resists venous back-pressure while allowing forward flow.

Endoluminal treatment of ruptured abdominal aortic aneurysm with small intestinal submucosa sandwich endografts: a pilot study in sheep

PURPOSE

To evaluate efficacy of small intestinal submucosa (SIS) Sandwich endografts for the treatment of acute rupture of abdominal aortic aneurysms (AAA) and to explore the short-term reaction of the aorta to this material.

METHODS

In eight adult sheep, an infrarenal AAA was created transluminally by dilation of a short Palmaz stent. In six sheep, the aneurysm was then ruptured by overdilation of the stent with a large angioplasty balloon. Two sheep with AAAs that were not ruptured served as controls. A SIS Sandwich endograft, consisting of a Z stent frame with 5 bodies and covered inside and out with SIS, was used to exclude the ruptured and non-ruptured AAAs. Follow-up aortography was done immediately after the procedure and before sacrifice at 4, 8, or 12 weeks. Autopsy and histologic studies followed.

RESULTS

Endograft placement was successful in all eight sheep. Both ruptured and non-ruptured AAAs were successfully excluded. Three animals with AAA rupture developed hind leg paralysis due to compromise of the arterial supply to the lower spinal cord and were sacrificed 1 day after the procedure. In five animals, three with rupture and two controls, follow-up aortograms revealed no aortic stenoses and no perigraft leaks. Gross and histologic studies revealed incorporation of the endografts into the aortic wall with replacement of SIS by dense neointima that was completely endothelialized in areas where the endograft was in direct contact with the aortic wall. In central portions of the endograft, in contact with the thrombosed aneurysm, endothelialization was incomplete even at 12 weeks.

CONCLUSION

The SIS Sandwich endografts effectively excluded simple AAAs and ruptured AAAs. They were rapidly incorporated into the aortic wall. A detailed long-term study is warranted.

Intraocular T cells of patients with herpes simplex virus (HSV)-induced acute retinal necrosis recognize HSV tegument proteins VP11/12 and VP13/14

It has previously been shown that T cells specific for the triggering virus infiltrate the eye of patients with herpes simplex virus type 1 (HSV-1)-induced acute retinal necrosis (ARN). The T cells were mainly directed against 0.67-0.73 HSV-1 map region encoded antigens. The fine specificities of genetically different T cell clones (TCC), obtained from affected eyes of 3 patients with HSV-induced ARN and reactive toward this genomic region of HSV-1, were analyzed with recombinant HSV viruses and synthetic peptides. For 1 patient, the HSV-1 UL46 gene encoded tegument protein VP11/12 was identified as the target antigen. Two separate CD4(+) T cell epitopes were defined in VP11/12. TCC from the other 2 patients recognized the HSV-1 UL47 gene encoded tegument protein VP13/14. Two separate CD4(+) VP13/14 T cell epitopes were identified in these patients. Analysis of the data indicates that HSV-1 VP11/12 and VP13/14 are major target antigens for T cells obtained from vitreous fluid samples of the HSV-induced ARN patients studied.

Treatment of refractory benign biliary stenoses in liver transplant patients by placement and retrieval of a temporary stent-graft: work in progress

PURPOSE

To evaluate patency of refractory benign biliary strictures in liver transplant patients treated with retrievable stent-grafts.

MATERIALS AND METHODS

Eight male liver transplant patients who ranged in age from 42 to 52 years developed nine symptomatic biliary strictures (intrahepatic left duct, 1; hilar, 2; anastomotic, 6). These strictures had recurred despite multiple previous attempts of treatment (n = 33), including angioplasty (n = 27), surgery (n = 1), atherectomy (n = 1), metallic stent (n = 1), and prolonged catheter drainage (n = 3). As an alternative method of treatment for these refractory biliary strictures, transhepatic placement of expanded polytetrafluoroethylene stent-grafts across the strictures was performed through 10-F sheaths. In total, 14 stent-grafts were placed to treat the nine lesions, and nine of these stent-grafts were subsequently retrieved through 12-16-F sheaths.

RESULTS

Stent-grafts were deployed successfully. Delayed migrations in two patients required additional stent-graft placement. One patient died of pneumonia 1 month after stent-graft placement; the remaining seven patients had stent-grafts successfully removed at 3-10 months (mean, 5.6 months). Nine intended stent-graft retrievals were performed successfully, with two requiring use of elongated forceps. Immediately after treatment, all strictures were widely patent. Five to 6 months after stent-graft removal in these seven patients, significant strictures recurred in four of eight lesions (50%). One patient underwent surgical revision. At 6-29 months (mean, 12 months) after stent-graft removal, the remaining six patients were without clinical or laboratory evidence of biliary obstruction, despite three patients with significant recurrent strictures.

CONCLUSION

Temporary stent-graft placement for treatment of benign biliary strictures in liver transplant patients is technically feasible. Longer follow-up with larger patient series is necessary to assess effectiveness and possible broader applications.

Percutaneous transjugular kidney biopsy in swine with use of a side-cutting needle with a blunt-tipped stylet

PURPOSE

To evaluate a new 19-gauge blunt-tipped, side-cutting, single throw transjugular biopsy needle for transvenous kidney biopsies.

MATERIALS AND METHODS

Transjugular transvenous kidney biopsies were performed with a modified 70-cm biopsy needle utilizing fluoroscopic guidance in nine swine. Three tissue specimens were obtained with four biopsy device passes in five animals and three biopsy device passes in four animals. Renal arteriography and venography were performed immediately before and after renal biopsy. Five animals were killed immediately after biopsy. Four animals were allowed to recover and underwent arteriography and venography prior to being killed, which varied from 1 to 6 weeks. Gross and histologic examinations of the biopsied kidney were performed after euthanasia. A pathologist reviewed all biopsy specimens for quality based on the number of glomeruli present.

RESULTS

Results of immediate and delayed arteriography and venography were normal in all cases. Histologic evaluation of all biopsy specimens demonstrated a range of two to 13 glomeruli per sample (mean, 6.5), with successful acquisition of the cortex. In one animal killed immediately after biopsy, a small subcapsular hematoma was present.

CONCLUSION

The 19-gauge, side-cut biopsy needle with a blunt-tip stylet proved to be efficacious for obtaining renal cortical samples in right swine kidneys via a transjugular approach.

Twin-tube endografts for aortic aneurysms: an experimental feasibility study

PURPOSE

To explore feasibility of twin-tube endografts (TTEGs) for treatment of abdominal aortic aneurysm (AAA).

MATERIALS AND METHODS

AAAs were created in six dogs by overdilation of Palmaz stents. TTEGs made of seven 9.5-mm-diameter Gianturco Rösch Z (GRZ) stents and covered with PTFE were deployed simultaneously from both femoral arteries through 10-F sheaths to exclude the AAA. Follow-up aortography was performed immediately and at 2, 4, and 8 weeks. Two dogs were killed at 4 weeks and four were killed at 8 weeks. Gross and histologic examinations were performed.

RESULTS

AAA creation and TTEG placement were successful in all six dogs. TTEGs completely excluded AAAs in five dogs. Minor temporary perigraft leak was seen in one dog immediately after stent placement. Four dogs had TTEGs patent to termination at 8 weeks. In two dogs with oversized TTEGs, one of the twin endografts occluded at 2 weeks. At autopsy, TTEGs were formed in semicircular shape and histology did not show any significant inflammatory reaction.

CONCLUSION

TTEGs show promise for treatment of AAA, with the potential of reducing the introductory sheath size. Further experimental studies, particularly with TTEGs extended into iliac arteries, are warranted.

Percutaneous retroperitoneal splenorenal shunt: an experimental study in swine

PURPOSE

To evaluate the technical possibility of creating a percutaneous retroperitoneal splenorenal shunt (PRESS) in swine as a minimally invasive treatment of portal hypertension.

MATERIALS AND METHODS

Five normal domestic swine underwent creation of a PRESS. A modified transjugular intrahepatic portosystemic shunt puncture set was introduced from the right femoral vein into the left renal vein. The proximal splenic vein was punctured transvenously through the retroperitoneal cavity. Noncovered metallic stents were then placed to connect both veins. The animals were sacrificed 1 hour after the procedure, after follow-up splenic venography and necropsy were performed.

RESULTS

Puncture of the splenic vein and stent placement were successfully completed in all cases. In four of five cases, the splenic venogram revealed good flow from the splenic vein to the left renal vein through the shunt track 1 hour after creation of the PRESS, and there was no evidence of leakage. No changes in vital signs were noticed. At necropsy, a small retroperitoneal hematoma along the stent and minimal intraperitoneal bleeding were observed. The stents were found in the retroperitoneal cavity connecting both veins in all animals.

CONCLUSION

Creation of a PRESS is technically possible, and further experimental studies of its efficacy are warranted.

Stent-grafts for revision of TIPS stenoses and occlusions: a clinical pilot study

PURPOSE

To assess the clinical and technical results of stent-graft placement for revision of transjugular intrahepatic portosystemic shunt (TIPS) stenoses and occlusions.

MATERIALS AND METHODS

Six patients who developed recurrent TIPS stenosis or occlusion of the parenchymal tract underwent shunt revision with use of polytetrafluoroethylene (PTFE) stent-grafts anchored at both ends by Z stents and centrally supported by Wallstents.

RESULTS

Before graft placement, mean primary patency was 50 days (range, 9-100 days). Patients underwent one to eight revisions with angioplasty or stent placement (mean, 3.2). Three patients had biliary-TIPS fistulas documented with use of a prototype double occlusion balloon catheter. Stent-grafts were successfully placed within the obstructed shunt, creating an excellent lumen in all cases. The portosystemic gradient was decreased from a mean of 24.3 mm Hg (range, 12-35 mm Hg) to a mean of 10.3 mm Hg (range, 7-16 mm Hg). Five of six patients were asymptomatic and no complications occurred (median clinical follow-up, 331 days). One patient died of pre-existing multi-organ system failure. The duration of primary patency after stent-grafting was improved (mean, 229 days; range, 27-324 days) and the difference approached statistical significance despite the small sample size (P = .056, paired t test). Three patients remained primarily patent at a mean venographic follow-up of 315 days. One shunt occluded at 1 month from residual thrombus in the portal vein, and one stenosis occurred that was secondary to misplacement of the original stent-graft. Patency was re-established in each of these patients.

CONCLUSION

PTFE covered stent-grafts are effective for shunt revision in patients with tract stenosis or occlusion and appear to improve TIPS patency.

Epitope specificity of murine and human bactericidal antibodies against PorA P1.7,16 induced with experimental meningococcal group B vaccines

Synthetic peptides derived from the predicted loops 1 and 4 of meningococcal PorA, sero-subtype P1.7,16, were used to study the epitope specificity of murine and human PorA P1.7,16 bactericidal antibodies. The predicted loops 1 and 4 are surface exposed and carry in their apices the sero-subtype epitopes P1.7 (loop 1) or P1.16 (loop 4), respectively. Peptides were synthesized as mono- and multimeric peptides. Murine monoclonal and polyclonal antibodies were induced with meningococcal whole cell preparations. Polyclonal antibodies were evoked in volunteers after one immunization with 50 micrograms or 100 micrograms protein of a hexavalent meningococcal PorA vesicle vaccine. The induction of PorA antibodies was determined in ELISA using purified PorA P1.7,16. The epitope specificity of anti-PorA antibodies for both murine and human antibodies could be demonstrated by direct peptide ELISA using overlapping multimeric peptides almost spanning the entire loops 1 or 4 of the protein. The capacity of peptides to inhibit the bactericidal activity of murine and human antibodies was investigated using meningococcal strain H44/76 (B:15:P1.7,16) as a target strain. Bactericidal activities could be inhibited with both monomeric and multimeric peptides derived from epitopes P1.7 and P1.16.

T-cell responses to outer membrane proteins of Neisseria meningitidis: comparative study of the Opa, Opc, and PorA proteins

Former studies have shown that the class 5 outer membranes proteins (Opa and Opc proteins) of Neisseria meningitidis are at least as immunogenic as meningococcal porin proteins. High antibody titers to class 5 proteins have been observed in sera obtained during convalescence after meningococcal infection. A strong increase in anti-class 5 antibodies has also been observed in vaccinees who received a meningococcal outer membrane vesicle preparation. The enhanced B-cell response to class 5 proteins may be due to the presence of immunodominant helper T-cell epitopes in these proteins. In order to investigate this hypothesis, we tested purified Opa, Opc, and class 1 proteins for recognition by human T cells. a hierarchy of T-cell immunogenicity was observed among the outer membrane proteins, the Opa protein being more immunogenic than the other proteins. In most cases, the proliferative responses elicited by Opc were higher than the responses observed for the class 1 protein. The epitopes recognized by the immune T cells were identified by using overlapping synthetic peptides spanning the protein sequences of OpaB, Opa5d, and Opc.

Conjugates of synthetic cyclic peptides elicit bactericidal antibodies against a conformational epitope on a class 1 outer membrane protein of Neisseria meningitidis

Bactericidal antibodies directed against surface loops of class 1 outer membrane proteins play a crucial role in protection against meningitis and sepsis caused by Neisseria meningitidis. So far, all efforts to obtain protective antibodies against these apparently conformational epitopes by using linear peptide analogs have been in vain. In this study, conjugates of head-to-tail cyclic peptides encompassing the predicted top of a protective surface loop were used for immunization. A series of 18 cyclic peptides with a ring size ranging from 7 to 17 residues, conjugated to tetanus toxoid, was investigated. Antipeptide and anti-whole-cell immunoglobulin G (IgG) titers elicited by the conjugates were determined. Conjugates of three peptides, containing 14, 15, and 17 amino acid residues (peptides 7, 12, and 13, respectively), induced an anti-whole-cell titer when Quillaja saponin A was used as the adjuvant. When alum was used as the adjuvant, the conjugate of peptide 12 did not elicit an anti-whole-cell response. From the Quillaja saponin A group, some of the sera obtained with conjugates of peptides 7 and 12 and all sera obtained with the peptide 13 conjugate were bactericidal in vitro. None of the sera evoked with alum as the adjuvant showed bactericidal activity. Nonbactericidal sera contained IgG1 primarily, whereas bactericidal sera showed significant titers of IgG2a and IgG2b. Class 1 protein-derived synthetic cyclic peptides which are capable of eliciting bactericidal antibodies, such as peptide 13 derived from meningococcal strain H44/76, represent potential candidates for a (semi)synthetic vaccine against meningococcal disease.

Improved transjugular intrahepatic portosystemic shunt patency with PTFE-covered stent-grafts: experimental results in swine

PURPOSE

To evaluate the ability of stent-grafts made with polytetrafluoroethylene (PTFE) graft material to improve transjugular intrahepatic portosystemic shunt (TIPS) patency.

MATERIALS AND METHODS

TIPS were created in 13 swine by using PTFE-covered stent-grafts. Uncovered TIPS were placed in 13 other swine. Twenty-one of 26 animals were followed up with portal venography for 3 months or until the shunt became severely stenotic. Five animals without severe stenosis were sacrificed before 3 months because of illness.

RESULTS

At 4 weeks after TIPS placement, nine of 13 stent-graft TIPS were patent (< 50% diameter narrowing) compared with only one patent stent in 13 uncovered TIPS. Six of 13 stent-graft TIPS remained patent until the animals were sacrificed. In 11 of 12 uncovered TIPS, stenosis was most prominent in the parenchymal tract. In five of seven stent-graft TIPS, stenosis was most prominent in the hepatic vein above the end of the graft material. Bile leaks were discovered in six occluded uncovered TIPS and in two of the stent-graft TIPS.

CONCLUSION

PTFE-covered stent-grafts significantly improved TIPS patency in swine (P < .01). However, stenosis in the hepatic vein led to late shunt malfunction in selected cases.

Treatment of malignant esophagorespiratory fistulas with silicone-covered metallic Z stents

PURPOSE

To prospectively evaluate the clinical efficacy of covered metallic Z stents in the treatment of esophagorespiratory fistulas (ERFs).

PATIENTS AND METHODS

Twelve patients with severe aspiration symptoms from malignant ERFs were treated with silicone-covered, metallic, self-expanding Gianturco-Rösch Z (GRZ) stents.

RESULTS

Fluoroscopically guided stent placement was successful and well tolerated in all patients. Immediate postprocedural endoscopy and esophagography showed excellent coverage of the fistulas in all cases. Aspiration symptoms were completely relieved in eight of 12 patients (67%). Four of 12 patients (33%) were improved and able to eat a soft diet. There were no stent-related deaths. Nine patients have died and three patients are alive. Mean follow-up for the entire group was 3.9 months (range, 1 week to 10.5 months). Nonfatal complications occurred in three of 12 patients (25%). Complications included one membrane disruption and one granulomatous reaction with a slight upward stent migration.

CONCLUSION

GRZ stents are an effective and safe means of palliation in patients with malignant esophagorespiratory fistulas.

Simultaneous multiple synthesis and selective conjugation of cyclized peptides derived from a surface loop of a meningococcal class 1 outer membrane protein

Starting from the alpha-(2,4-dimethoxybenzyl) ester of N-(9-fluorenylmethoxycarbonyl)aspartic acid [Fmoc-Asp-ODmb], side-chain-protected resin-bound Fmoc-peptides containing an N epsilon-1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl lysyl [Lys(Dde)] residue were prepared. The C-terminal dimethoxybenzyl esters of aspartic acid were removed with 1% trifluoroacetic acid and 10% anisole in dichloromethane, followed by Fmoc-cleavage in the usual manner. The resin-bound peptides were then cyclized using 1-benzotriazolyloxy-tris-[N-pyrrolidino]phosphonium hexafluorophosphate (PyBOP) in the presence of N-methylmorpholine. The (dimethyldioxocyclohexylidene)ethyl groups of lysine were removed with 1% hydrazine hydrate in N,N-dimethylacetamide, and the liberated side-chain amino functions were modified by reaction with pentafluorophenyl S-acetylmercaptoacetate (SAMA-OPfp). Finally, the peptides were side-chain deprotected, with exception of the Lys(SAMA) residue, and cleaved from the solid support with trifluoroacetic acid/anisole/water, 95/2.5/2.5. Cyclic peptides comprising 7-14 amino acid residues were obtained employing this procedure. As a model conjugation, cyclo[Thr-Asn-Asn-Asn-Leu-Lys(SAMA)-Thr-Lys-Asp] was coupled with bromoacetamide. The same peptide was also coupled with a bromoacetylpeptide to give a well defined peptide/peptide conjugate. All peptides were conjugated to bromoacetylated tetanus toxoid for immunization purposes.

In vitro comparison of the spiral Z stent and the Gianturco Z stent

A new spiral Z stent is described, and its characteristics are compared in vitro with those of the modified Gianturco Z stent. The spiral Z stent has a more uniform expansile force throughout its effective length; is more compressible, thus allowing for use of a smaller introductory catheter; and is more stable than the modified Z stent. Flexibility of both stent types is similar. Advantages of the spiral Z stent promise to be beneficial for clinical use.

Purification, cyanogen bromide cleavage, and amino terminus sequencing of class 1 and class 3 outer membrane proteins of meningococci

Meningococcal class 1 and 3 outer membrane proteins (OMPs) were subjected to cyanogen bromide treatment. The class 3 OMP was found to be resistant to cyanogen bromide, while the class 1 OMP was cut into two main fragments of 25 and 17 kilodaltons. The N-terminal sequences were determined for class 1 and class 3 proteins, which exhibit similarities to one another and to OMP I of gonococci. The C-terminal class 1 OMP fragment bound the bactericidal monoclonal antibodies tested.

Comparison of meningococcal outer membrane protein vaccines solubilized with detergent or C polysaccharide

Outer membrane proteins (OMPs) were isolated from meningococcal strain H44/76 (B:15:P1.16) by detergent extraction of bacteria. A final product containing class 1 (P1.16), 3(15), 4 OMPs and 5% (w/w) lipooligosaccharide was obtained. Two experimental vaccines were prepared: OMP-detergent and OMP-C polysaccharide. The OMP-detergent vaccine tended to show a better bactericidal: ELISA ratio for the antibodies induced as compared to the OMP-C polysaccharide vaccine. The vaccine induced bactericidal antibodies appeared for the greater part to be directed against the class 1 OMP (P1.16). By comparison of cultures grown in Mueller Hinton Broth with and without 0.25% (w/v) glucose, it was found that monoclonal antibodies against the serotype OMP (class 2 or 3) were not bactericidal against meningococci grown in MHB without glucose. Antibodies against class 1 OMP and lipooligosaccharide were not influenced by this. A new major outer membrane protein (appr. 40 kd) is described that may function as a cation-specific porin.

Tamoxifen suppresses both the growth of prolactin-secreting pituitary tumours and normal prolactin synthesis in the rat

The effect of administering the antioestrogenic drug, tamoxifen, on the growth of the pituitary tumour 7315a in the rat was studied. This tumour is induced by the administration of oestrogen. When administered early after the implantation of the tumour, tamoxifen prevented its growth completely but when treatment was delayed until a later stage of its development, 20 microgram tamoxifen/100 g body wt each day for 7-12 days stopped further tumour growth, while 200 microgram/100 g body wt each day reduced the size of the tumours. These effects of tamoxifen on tumour growth were accompanied by a decrease in the level of prolactin in the circulation, if the treatment was started at an early stage of tumour development and if the high dose of tamoxifen was administered. Bromocriptine either when given alone or together with tamoxifen was unable to inhibit growth and secretion of prolactin by these rat pituitary tumours. The high plasma concentrations of prolactin in the tumour-bearing rats are known to produce atrophy of the pituitary gland of the host and to decrease the synthesis and release of prolactin. Despite the inhibitory effect of tamoxifen on both tumour size and plasma levels of prolactin, the ability of the pituitary glands of these animals to synthesize prolactin remained suppressed. It was concluded that tamoxifen has a dual effect on this model of a transplantable pituitary tumour that secretes prolactin in the rat; it prevents and/or inhibits tumour growth and it has an inhibitory effect on the synthesis of prolactin by the pituitary gland.

Depressed plasma FFA turnover rate in Cushing's syndrome

The turnover rate of plasma FFA measured by constant infusion of albumin-complexed labeled palmitate in a group of 16 patients with Cushing's syndrome was significantly lower than in a group of 6 controls. Seven patients reexamined after correction of the hypercortisolism showed a normalization of the plasma FFA turnover rate. By contrast, 7 patients with simple obesity had a normal or increased plasma FFA turnover rate depending on the way this parameter is expressed.

The mechanism of the potentiating effect of glucocorticoids on catecholamine-induced lipolysis

Preincubation of isolated epididymal fat cells with dexamethasone or treating rats with cortisol enhances the epinephrine-stimulated lipolysis of the cells as well as cAMP-dependent protein kinase activity in homogenates of these fat cell suspensions. During maximal inhibition of phosphodiesterase activity by theophylline or dibutyryl cAMP, this potentiating effect of glucocorticoids on the fat cells was also present. There was no lowering of the total phosphodiesterase activity in homogenates of fat cell suspensions of rats that were treated with cortisol, but there appeared to be a lower activity of the low KM phosphodiesterase activity. It is concluded that induction of protein kinase by glucocorticoid hormone is responsible for its special type of stimulative action on lipolysis.