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At least 19 recordsLinked to original sources
PubMed1999

Effect of relaparotomy through previously integrated polypropylene and polytetrafluoroethylene experimental implants in the abdominal wall.

BACKGROUND: The appearance of new pathologies affecting abdominal organs after implant of a prosthesis to repair an abdominal wall defect may necessitate reintervention. The aim of this study was to compare the behavior of two types of biomaterial widely used in clinical practice, polypropylene (PL) and polytetrafluoroethylene (ePTFE), after a second laparotomy involving the implant. The behavior, in terms of tensile resistance and integration with tissues, of intact prostheses was compared to that of prostheses subjected to opening and repair. METHODS: A defect (7x5 cm) involving all tissue layers was created in the anterior abdominal wall of 24 male New Zealand rabbits. These defects were repaired with a reticular, macroporous PL mesh (Marlex, Bard Card., Madrid, Spain) or a laminar, micro/macroporous ePTFE prosthesis (Mycro Mesh, W.L. Gore, Flagstaff, AZ) of similar size to the defect. Four study groups were established: Intact PL/Intact ePTFE (n = 6 each): animals implanted with a PL or ePTFE prosthesis and sacrificed 90 days after implant; Repaired PL/Repaired ePTFE (n = 6 each): animals implanted with a PL or ePTFE prosthesis subjected to midlongitudinal relaparotomy through the center of the prosthesis 90 days postimplant, followed by repair with continuous polypropylene 4/0 suture. Animals in repaired groups were sacrificed 90 days after the second intervention. Specimens comprised of prosthesis and neoformed tissue were subjected to light and scanning electron microscopy. In addition, 2 cm-wide strips, consisting of the prosthesis and anchorage tissue, were subjected to biomechanical analysis using an Instron tensiometer (Instron, Canton, MA). The results obtained were statistically compared using the Mann-Whitney U-test. RESULTS: The intact PL implants were fully infiltrated by dense, disorganized, well-vascularized scar tissue with fibers concentric to the mesh monofilaments. The appearance of the repaired PL prostheses was similar, with establishment of neoformed tissue in repaired areas of the prosthesis such that both cut edges of the prosthesis were joined together. In contrast, intact ePTFE prostheses were encapsulated by organized tissue with fibers running parallel to the surface of the biomaterial. Repaired ePTFE prostheses including sutured areas were similarly encapsulated. But the edges of the sutured middle area did not fuse. Tensile resistance values of intact and repaired PL prostheses were similar (intact, mean, 34.78 Newtons; repaired, mean, 34.74N, p>0.001). Tensile resistance values of intact ePTFE implants were significantly different to those of the repaired ePTFE prostheses (intact, mean, 22.64N; repaired, mean, 17.21N, p<0.001). Breakage of both types of PL specimen strips was restricted to recipient tissue while breakage of intact ePTFE specimens occurred in the areas of anchorage to the abdominal wall. Rupture of repaired ePTFE specimens took place in the sutured central areas of the prostheses. CONCLUSIONS: We conclude that relaparotomy through an existing PL prosthesis previously integrated with the abdominal wall does not affect the tissue integration process or the tensile resistance of the implant. When the relaparotomy involves an ePTFE prosthesis, however, although the repair process itself is unaffected, significant loss in tensile strength is incurred. In addition, relaparotomy through both types of biomaterial is likely to result in the neoformation of adhesions in the areas of the prosthesis subjected to opening and repair but, in general, the number of adhesions formed in the presence of intact or repaired polypropylene implants was larger than that observed with the use of ePTFE.

Abdominal Muscles↗
PubMed2003

Antitumor and immunomodulatory activity of resveratrol on experimentally implanted tumor of H22 in Balb/c mice.

AIM: To study the antitumor and immunomodulatory activity of resveratrol on experimentally implanted tumor of H22 in Balb/c mice. METHODS: The cytotoxicity of peritoneal macrophages (Mphi) against H22 cells was measured by the radioactivity of ((3)H)TdR assay, mice with H22 tumor were injected with different concentrations of resveratrol, and the inhibitory rates were calculated and IgG contents were determined by single immunodiffusion method. the plaque forming cell (PFC) was measured by improved Cunningham method, the levels of serum tumor necrosis factor-alpha (TNF-alpha) were measured by cytotoxic assay against L929 cells. RESULTS: Resveratrol 2.5 mg x L(-1), 5.0 mg x L(-1), 10.0 mg x L(-1), 20.0 mg x L(-1) (E:T=10:1, 20:1) promoted the cytotoxicity of Mphi against H22 cells. Resveratrol ip 500 mg x kg(-1), 1 000 mg x kg(-1) and 1,500 mg x kg(-1) could curb the growth of the implanted tumor of H22 in mice. The inhibitory rates were 31.5 %, 45.6 % and 48.7 %, respectively (P<0.05), which could raise the level of serum IgG and PFC response to sheep red blood cell. Resveratrol 1,000 mg x kg(-1) and 1,500 mg x kg(-1) and BCG 200 mg x kg(-1) ip could increase the production of serum TNF-alpha in mice H22 tumor. However, the effect of resveratrol was insignificant (P>0.05). CONCLUSION: Resveratrol could inhibit the growth of H22 tumor in Balb/c mice. The antitumor effect of resveratrol might be related to directly inhibiting the growth of H22 cells and indirectly inhibiting its potential effect on nonspecific host immunomodulatory activity.

Adjuvants, Immunologic↗
PubMed1995

Separation of the natural atria in experimental implantation of total artificial heart.

Atrial connections in a single-unit total artificial heart (TAH) may be difficult to make because of the rigidity of the device and the fixed position of the atrial inlets. We developed a technique to separate the natural atrial borders in an experimental implantation of a unitary TAH. In this technique, the interatrial groove was dissected to separate the posterior wall of the right atrium from the roof of the left atrium before cardiopulmonary bypass (CPB) was initiated. After initiation of CPB and cardiectomy, the atrial septum was separated completely, and the right atrial wall was reconstructed with glutaraldehyde-treated autopericardium. We believe that this simple adjunctive technique provides increased mobility of the atrial cuffs and allows for an easier connection of the unitary TAH.

Animals↗
PubMed1989

Experimental implantation of adipose tissue fragments.

The healing of small adipose tissue implants was evaluated in experimental studies on rats. Adipose tissue of approximately 0.5 ml volume was obtained by resection of parauterine fat pads. The tissue was divided into fragments that were 1-3 mm in size and implanted under the dorsal skin. The implantation of adipose tissue in fragments offered no biological advantage and the healing process terminated in extensive necrosis of fat cells. The results are analysed and considered in relation to the implantation of adipose tissue fragments obtained by liposuction.

Adipose Tissue↗
PubMed2006

Oxidized, bioactive implants are rapidly and strongly integrated in bone. Part 1--experimental implants.

OBJECTIVES: The study presented was designed to investigate the speed and the strength of osseointegration of oxidized implants at early healing times in comparison which machined, turned implants. MATERIAL AND METHODS: Screw-shaped titanium implants were prepared and divided into two groups: magnesium ion incorporated, oxidized implants (Mg implants, n=10) and machined, turned implants (controls, n=10). Mg implants were prepared using micro-arc oxidation methods. Surface oxide properties of implants such as surface chemistry, oxide thickness, morphology/pore characteristics, crystal structures and roughness were characterized with various surface analytic techniques. Implants were inserted into the tibiae of ten New Zealand white rabbits. After a follow-up period of 3 and 6 weeks, removal torque (RTQ), osseointegration speed (DeltaRTQ/Deltahealing time) and integration strength of implants were measured. Bonding failure analysis of the bone-to-implant interface was performed. RESULTS: The speed the and strength of osseointegration of Mg implants were significantly more rapid and stronger than for turned implants at follow-up periods of 3 and 6 weeks. Bonding failure for Mg implants dominantly occurred within the bone tissue, whereas bonding failure for turned implants mainly occurred at the interface between implant and bone. CONCLUSIONS: Oxidized, bioactive implants are rapidly and strongly integrated in bone. The present results indicate that the rapid and strong integration of oxidized, bioactive Mg implants to bone may encompass immediate/early loading of clinical implants.

Animals↗
PubMed1985

[Utero-ovarian implantation. Experimental study and critical evaluation of its use in women].

The authors studied experimentally ovario-uterine implantation in rats, an operation first performed many years ago yielding very rare and debatable results. This procedure is ineffective in the treatment of sterility due to endometrial proliferation over the ovary, which closes off rapidly the endometrial cavity and separates it from the implanted ovary. Much uncertainty surrounds the majority of previously reported successes, the few resultant pregnancies from ovario-uterine implantation considered due to hazard and completely unreliable. This operation has no place in the treatment of sterility.

Animals↗
PubMed2006

Transapical approach for sutureless stent-fixed aortic valve implantation: experimental results.

OBJECTIVE: Percutaneous aortic valve implantation has been performed in patients with severe aortic stenosis judged as nonsurgical candidates. We evaluated a facilitated transapical antegrade approach for potential use in surgical high-risk patients. METHODS: A pericardial xenograft fixed within a 23-mm stent (Cribier-Edwards aortic prosthesis, Edwards Inc., Irvine, CA, USA) was implanted using a transapical approach in fifteen 35-45 kg pigs. A limited or a full sternotomy was used to transapically introduce a crimped valve through a 24-F sheath. Deployments were performed on the beating heart either with ventricular unloading using femoro-femoral cardiopulmonary bypass (CPB) or rapid ventricular pacing (RVP), all under fluoroscopic and echocardiographic visualization. RESULTS: All valves were successfully deployed at the target site with acceptable visualization of the noncalcified annulus. Valve migration occurred in six procedures (three distal and three retrograde) secondary to inadequate reduction of ventricular output, unfavorable annular anatomy, excessive crimping of the valve, and dislodgement by the delivery balloon. Exact positioning of the valve into the target area was confirmed by autopsy at the end of the procedures. Paravalvular leak was noted in five implants. CONCLUSIONS: The transapical approach provides a safe, accurate, and effective route for facilitated antegrade delivery of a stent-fixed valve. Advanced stent design will lead to better stability of the implant and may minimize the risk of paravalvular leakage in future. Identifying the appropriate population for human feasibility trials remains a challenge.

Animals↗
PubMed2005

Superior sealing effect of hydroxyapatite in porous-coated implants: experimental studies on the migration of polyethylene particles around stable and unstable implants in dogs.

BACKGROUND: Migration of wear debris to the periprosthetic bone is a major cause of osteolysis and implant failure. Both closed-pore porous coatings and hydroxyapatite (HA) coatings have been claimed to prevent the migration of wear debris. We investigated whether HA could augment the sealing effect of a porous coating under both stable and unstable conditions. METHODS: We inserted porous-surfaced knee implants, with and without HA coating, in 16 dogs, according to a paired, randomized study design. 8 dogs had 2 implants inserted into each knee using a stable implant device and 8 dogs received 1 implant in each knee using a micromotion (500 microm) implant device. Implants had a peri-implant gap of 0.75 mm. We then injected polyethylene (PE) particles or a control solution into the knee joints on a weekly basis. RESULTS: After 16 weeks, the rating of particles around stable implants was reduced by the HA coating froma median value of 2 (1-4) to 1 (0-1) (p = 0.01) and during micromotion from 3 (2-4) to 1 (0-3) (p = 0.002). HA-coated implants had superior bone ongrowth during stable and unstable conditions. We found no difference in bone ongrowth between PE-exposed and vehicle-exposed implants. INTERPRETATION: Compared to a pure plasma-sprayed porous coating, a layer of HA coating provides bettter bone ongrowth and protects the bone-implant interface against the migration of wear debris under both stable and unstable conditions.

Animals↗
PubMed1981

Al2O3-ceramic as material for dental implants: experimental and clinical study for the development of screw- and extension-implants.

A screw implant and a blade-vent implant were developed for the alloplastic substitution of teeth. Forty implants were observed for 18 months in five beagles; these implants were under maximal functional mastication. No implant was lost. The screw implant showed a tight attachment of bone over the whole implant surface. With the blade-vent implant we observed a partial interposition of connective tissue. This difference seems to depend on the different insertion techniques. Photoelastic studies showed a good stress distribution through enlarged and rounded off attachment surfaces. The described insertion techniques allowed a primary tight attachment of the implant surface and bone support, which led to an immediate stability of position. In the screw implant the physiologic mobility of teeth was imitated by means of a resilient element. Data from 30 cases were gained in a clinical 3-year follow-up. One case failed. For conclusive judgement, a longer period of time and more clinical cases are necessary, but existing data are encouraging.

Aluminum↗
PubMed1994

[Computer-assisted experimental implantation technique for comparative quality assessment of various cementation techniques in cemented hip prosthesis implantation].

For the anchorage of femoral prosthesis stems in total hip arthroplasty, various cement application techniques are used. Experimental comparison of these techniques requires a set-up in which only the cementing technique itself is tested. We used a computer-controlled implantation device based on a milling machine and standardized artificial femur models. The stems are reproducibly positioned by the machine and any influence of manual positioning during the implantation is excluded. The results can be evaluated macroscopically and radiologically with no interference by disturbing bone--with sufficient sensitivity to objectify differences in cement quality. The increase in pressure in the peripheral medullary cavity, which is responsible for the embolisation, can be determined experimentally for the individual cementing technique. The experimental implantation device described enables a standardized comparison of various cementing techniques.

Bone Cements↗