In vivo efficacy of antimicrobial-coated devices

BACKGROUND: Since device colonization is a prelude to infection, an antimicrobial-coated device that reduces bacterial colonization can potentially protect against infection. The objective of this animal study was to assess the efficacy of a coating with minocycline and rifampin to prevent colonization of a grit-blasted titanium implant and subsequent osteomyelitis. METHODS: Twenty-five rabbits underwent implantation of a titanium-alloy pin, either coated with minocycline and rifampin (thirteen rabbits) or uncoated (twelve rabbits), into the right femoral medullary canal. The implanted devices were inoculated with 500 CFU (colony-forming units) of Staphylococcus aureus prior to wound closure. The rabbits were killed one week later, and the removed device, femoral bone, a specimen obtained by swabbing the track surrounding the device, and blood were cultured. The rates of device colonization, osteomyelitis, and device-related osteomyelitis were compared between the two groups of rabbits. RESULTS: The antimicrobial-coated devices had a significantly lower rate of colonization than the uncoated devices (five of thirteen compared with twelve of twelve, p = 0.0016) and were associated with significantly lower rates of osteomyelitis (six of thirteen compared with twelve of twelve, p = 0.005) and device-related osteomyelitis (five of thirteen compared with twelve of twelve, p = 0.0016). Bacteremia did not develop in any rabbit. CONCLUSIONS: Orthopaedic devices coated with minocycline and rifampin significantly protected against device colonization and infection due to Staphylococcus aureus in this in vivo rabbit model. CLINICAL RELEVANCE: It is possible that orthopaedic devices coated with this unique combination of antimicrobial agents may protect against the development of clinical infection in humans.     

In vivo efficacy of a new autologous fibrin sealant

BACKGROUND: Fibrin-based sealants are commonly used to arrest bleeding following surgery. A new method has been developed for preparation of autologous fibrin sealant (FS) from protamine-precipitated fibrinogen concentrate. This FS has the potential to be a low-cost, safe, and convenient alternative to commercial sealants or cryoprecipitates usually prepared from patient or banked plasma. In this study, the efficacy of human FS was evaluated in a rat kidney model. MATERIALS AND METHODS: FS containing various fibrinogen concentrations (ranging from 15 to 60 mg/mL) were applied to controlled renal incisions, and bleeding time and blood loss were measured. Bleeding from the wounds was also predicted using a mathematical model based on tensile strength and adhesion strength of the sealants. RESULTS: The sealants, when applied under controlled conditions, reduced the blood loss and bleeding time more effectively than controls (where no sealant, plasma, or the commercial product Tisseel (Baxter Healthcare Corp., Westlake Village, CA) was applied). The sealant also significantly reduced bleeding time with a concomitant decrease in blood loss in rats that were anticoagulated with heparin. Bleeding times predicted by the mathematical model agreed well with experimental data and demonstrated that the ability of sealant to reduce bleeding time largely depended on its adhesion strength. CONCLUSION: The autologous fibrin sealant can be prepared with any volume (e.g., 5 to 500 mL) of patient's blood, within minutes, and exhibits equal or greater hemostatic efficacy compared with the leading commercial sealant.     

In vivo efficacy of low-level laser therapy on bone regeneration

Lasers in Medical Science - In clinical use of low-level laser therapy for bone regeneration (LLLT), application protocol (dose, duration, and repetitions) has not been established. This study...     

In vivo functional performance of failed prodisc-L devices: retrieval analysis of lumbar total disc replacements

STUDY DESIGN.: A retrieval analysis of wear modes and fixation of lumbar total disc replacements (TDRs). Explanted Prodisc-L TDRs were prospectively collected during a 7-year period (2005-2011) and analyzed. OBJECTIVE.: To assess the in vivo modes of wear and fixation of lumbar TDR with the Prodisc-L device. SUMMARY OF BACKGROUND DATA.: Inferior clinical outcomes and failure of lumbar TDR may occur because of suboptimal component fixation, wear properties, and impingement in a subset of patients. Posterior component TDR impingement has been demonstrated radiographically; however, despite its widespread use, the in vivo mechanical performance and fixation of the Prodisc-L device remain unknown. METHODS.: Explanted polyethylene and metallic (CoCrMo) components of Prodisc-L devices were examined by light stereo-microscopy (6X-31X), scanning electron microscopy, and energy-dispersive x-ray analysis from an international retrieval registry, with 13 participating surgeons. RESULTS.: Nineteen ProDisc-L devices from 18 patients (age, 44.7 ± 2.9 yr) following an index TDR at L4-L5 (n = 6), L5-S1 (n = 11), and unknown level (n = 2) were explanted for pain (n = 8), prosthesis subluxation/migration (n = 4), end plate collapse/subsidence (n = 3), polyethylene dislodgement (n = 3), and unknown (n = 2) after a mean length of implantation of 13.0 ± 3.9 months. Surface area of bony ongrowth was 9.6 ± 2.9% (range, 0%-52.5%). TDR burnishing was observed posteriorly consistent with component impingement in extension in 53% (8/15) (P < 0.02), more commonly than anterior 20% (3/15) lateral 20% (n = 3) (3/15) patterns. Circumferential burnishing was not observed. Posterior impingement was associated with 6° lordotic implants (P < 0.05) and 10-mm polyethylene size (P < 0.05). Backside wear occurred in 75% (9 of 12) of the disassembled implants and third-body wear was observed in 33% (5 of 15). CONCLUSION.: Metallic end plate burnishing was evident in a large percentage of clinically failed Prodisc-L TDR devices, most commonly posteriorly, consistent with impingement in extension. Long-term follow-up studies will evaluate the effects of the observed backside wear, third-body wear, and end plate impingement on clinical outcomes.     

In vivo antibacterial efficacy of MONOCRYL plus antibacterial suture (Poliglecaprone 25 with triclosan)

BACKGROUND: This study evaluated the ability of poliglecaprone 25 suture with triclosan to inhibit bacterial colonization by Escherichia coli and Staphylococcus aureus in mouse and guinea pig models. METHODS: Test and control sutures (3-4 cm) were implanted subcutaneously in the dorsal-lateral regions (control on the left side, test on the right side, approximately 3-5 cm apart) in 10 female Hartley guinea pigs (300-400 g) and 10 Swiss Webster mice (20-35 g) via a 20-gauge catheter. The test material was poliglecaprone 25 suture with triclosan (2-0, undyed), and the control material was poliglecaprone 25 suture (2-0, undyed). In the guinea pig model, each implantation site was challenged directly with 4x10(5) colony-forming units (cfu) of S. aureus, whereas in the mouse model, each implantation site was challenged directly with 1.3x10(7) cfu of E. coli through an indwelling catheter. At 48 h post-implantation, the control and test sutures were explanted, and bacterial enumeration was performed. RESULTS: There was a significant difference (p < 0.05) in the number of bacteria recovered in the study groups 48 h post-implantation. Poliglecaprone 25 suture with triclosan produced a 3.4-log reduction in S. aureus and a 2-log reduction in E. coli compared with standard poliglecaprone 25 suture without triclosan under the same challenge conditions. The difference between the study groups in the number of bacteria recovered was significant (p < 0.05). CONCLUSION: Poliglecaprone 25 suture with triclosan inhibited bacterial colonization of the suture compared with untreated suture after direct in vivo challenge with S. aureus and E. coli in animal models.     

In vivo bactericidal efficacy of the Ti6Al4V surface after ultraviolet C treatment

Background

Biomaterial-associated infections are one of the most important complications in orthopedic surgery. The main goal of this study was to demonstrate the in vivo bactericidal effect of ultraviolet (UV) irradiation on Ti6Al4V surfaces.

Materials and methods

An experimental model of device-related infections was developed by direct inoculation of Staphylococcus aureus into the canal of both femurs of 34 rats. A UV-irradiated Ti6Al4V pin was press-fit into the canal by retrograde insertion in one femur and the control pin was inserted into the contralateral femur. To assess the efficacy of UV radiation, the mean colony counts after inoculation in the experimental subjects and the control group were compared at different times of sacrifice and at different inoculum doses.

Results

At 72 h, the mean colony counts after inoculation in experimental femurs were significantly lower than those of the control group, with a reduction percentage of 76 % (p = 0.041). A similar difference between control and experimental pins was observed at 24 h using an inoculum dose <10⁴ colony-forming units (CFU), for which the reduction percentage was 70.48 % (p = 0.017).

Conclusion

The irradiated surface of Ti6Al4V is able to reduce early bacterial colonization of Ti6AlV pins located in the medullar channel and in the surrounding femur. The reductions depend on the initial inoculums used to cause infection in the animals and the greatest effects are detected for inoculums <10⁴ CFU.

Level of evidence

Not applicable.

     

In vivo and in vitro antibacterial efficacy of PDS plus (polidioxanone with triclosan) suture

ABSTRACT Background: This study evaluated the efficacy of polydioxanone suture with and without triclosan against gram-positive and gram-negative bacteria in vitro and in vivo. Methods: Polydioxanone suture with and without triclosan was tested against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), S. epidermidis, methicillin-resistant S. epidermidis (MRSE), Klebsiella pneumoniae, and Escherichia coli by a zone of inhibition assay. In vivo evaluations were conducted in guinea pigs and mice in which test and control sutures (3-4 cm long) were implanted subcutaneously in the dorsal-lateral regions (control on left, test on right, 3-5 cm apart) through a 20 gauge catheter. Each implantation site was then challenged directly through the catheter with 4 x 10(5) colony-forming units (CFU) of S. aureus (guinea pigs) or 7 x 10(6) CFU of E. coli (mice). At 48 h post-implantation, the control and test sutures were explanted, and adherent bacteria were counted. Results: Polydioxanone suture with triclosan demonstrated activity against all test organisms in vitro. The antibacterial activity was maintained until the sutures dissolved after 17 to 23 days when tested against E. coli and S. aureus, respectively. Evaluation in animal models demonstrated a 99.9% reduction in S. aureus and a 90% reduction in E. coli relative to controls. Conclusion: Polydioxanone suture with triclosan had activity in vitro against S. aureus, MRSA, E. coli, S. epidermidis, MRSE, and K. pneumoniae that persisted for as long as three weeks. In animal models, polydioxanone suture with triclosan inhibited in vivo colonization by S. aureus and E. coli.     

体内组织工程技术—小肠黏膜下层的应用

组织工程技术分为两类 :一类称为体外组织工程技术 ;另一类为体内组织工程技术。1　体外组织工程技术体外组织工程技术先从宿主组织中取得宿主细胞 ,在体外进行培养 ,再植入到某种可降解生物材料中 ,这样组成复合植入物 ,一同植回宿主体内 ,使其继续再生过程〔1～ 3〕。体外组织工程技术目前存在许多困难。首先 ,体外组织工程所取得的宿主细胞在传代过程中的分化、变异目前尚没有办法进行很好的控制 ,因此 ,宿主细胞在体外达到有效浓度就极为困难 ,更不用说由宿主细胞行使有效的代谢功能。这样 ,植回宿主体内的仍然是生物可降解材料和少量宿…     

In vivo robotic laparoscopy

Laparoscopy reduces patient trauma but limits the surgeon's ability to view or touch the surgical environment directly. The surgeon's ability to visualize and manipulate target organs can be improved using currently available external robotic systems. However, tool tip orientation and optimal camera placement remain limited because the robot instruments and cameras are still constrained by the entry incisions. Placing a robot completely within the abdominal cavity would provide an unconstrained platform that could provide an enhanced field of view from arbitrary angles and dexterous manipulators not constrained by the abdominal wall fulcrum effect. Several in vivo robots have been developed and successfully tested in a porcine model. These in vivo robots have been used to observe trocar and tool insertions and placement, and to provide additional camera angles that improved surgical visualization. Equipped with a grasper, such robots will provide task assistance. These in vivo robots will be much less expensive than the current generation of large external robotic surgical systems and will ultimately allow a surgeon to be a remote first responder irrespective of the location of the patient.     

In vivo laparoscopic robotics

Robotic laparoscopic surgery is evolving to include in vivo robotic assistants. The impetus for the development of this technology is to provide surgeons with additional viewpoints and unconstrained manipulators that improve safety and reduce patient trauma. A family of these robots have been developed to provide vision and task assistance. Fixed-base and mobile robots have been designed and tested in animal models with much success. A cholecystectomy, prostatectomy, and nephrectomy have all been performed with the assistance of these robots. These early successful tests show how in vivo laparoscopic robotics may be part of the next advancement in surgical technology.     

In vivo study of the efficacy of bupivacaine-eluting novel soy protein wound dressings in a rat burn model

Dealing with wound related pain is an integral part of treatment. Systemic administration of analgesic and anesthetic agents is a common solution for providing pain relief to patients but comes at a risk of severe side effects as well as addiction. To overcome these issues, research efforts were madeto provide a platform for local controlled release of pain killers. We have developed a bilayer soy protein-based wound dressing for the controlled local release of bupivacaine to the wound site. The combination of a dense and a porous layer provides a platform for cell growth and proliferation as well as physical protection to the wound site. The current study focuses on the in vitro bupivacaine release profile from the dressing and the corresponding in vivo results of pain levels in a second-degree burn model on rats. The Rat Grimace Scale method and the Von Frey filaments method were used to quantify both, spontaneous pain and mechanically induced pain. A high burst release of 61.8 ± 1.9% of the loaded drug was obtained during the initial hour, followed by a slower release rate during the following day. The animal trials show that the RGS scores of the bupivacaine-treated group were significantly lower than these of the untreated group, proving a decrease of 51–68% in pain levels during days 1–3 after burn. Hence, successful pain reduction of spontaneous pain as well as mechanically induced pain, for at least three days after burn was achieved. It is concluded that our novel bupivacaine eluting soy protein wound dressings are a promising new concept in the field of local controlled drug release for pain management.     

In vitro performance and principles of anti-siphoning devices

Background

Anti-siphon devices (ASDs) of various working principles were developed to overcome overdrainage-related complications associated with ventriculoperitoneal shunting.

Objective

We aimed to provide comparative data on the pressure and flow characteristics of six different types of ASDs (gravity-assisted, membrane-controlled, and flow-regulated) in order to achieve a better understanding of these devices and their potential clinical application.

Methods

We analyzed three gravity-dependent ASDs (ShuntAssistant [SA], Miethke; Gravity Compensating Accessory [GCA], Integra; SiphonX [SX], Sophysa), two membrane-controlled ASDs (Anti-Siphon Device [IASD], Integra; Delta Chamber [DC], Medtronic), and one flow-regulated ASD (SiphonGuard [SG], Codman). Defined pressure conditions within a simulated shunt system were generated (differential pressure 10–80 cmH₂O), and the specific flow and pressure characteristics were measured. In addition, the gravity-dependent ASDs were measured in defined spatial positions (0–90°).

Results

The flow characteristics of the three gravity-assisted ASDs were largely dependent upon differential pressure and on their spatial position. All three devices were able to reduce the siphoning effect, but each to a different extent (flow at inflow pressure: 10 cmH₂O, siphoning -20 cmH₂O at 0°/90°: SA, 7.1?±?1.2*/2.3?±? 0.5* ml/min; GCA, 10.5?±?0.8/3.4?±?0.4* ml/min; SX, 9.5?±?1.2*/4.7?±?1.9* ml/min, compared to control, 11.1?±?0.4 ml/min [*p?2O/ siphoning -20cmH₂O: DC, 2.6?±?0.1/ 4?±?0.3* ml/min; IASD, 2.5?±?0.2/ 0.8?±?0.4* ml/min; SG, 0.8?±?0.2*/ 0.2?±?0.1* ml/min [*p?Conclusion The tested ASDs were able to control the siphoning effect within a simulated shunt system to differing degrees. Future comparative trials are needed to determine the type of device that is superior for clinical application.     

In vitro comparison of 4 ultrasound lithotripsy devices

PURPOSE: Endoscopic lithotripsy is still the method of choice for a number of stones, especially large renal stones. Various disintegration techniques exist. Ultrasound is widely used because it is the only method that allows disintegration and active suction of stone debris at the same time. We evaluated 4 ultrasound lithotriptors in vitro. MATERIALS AND METHODS: We used a newly developed experimental setup and compared 4 ultrasound devices, namely the 27085 K (Karl Storz Endoscopy, Tuttlingen, Germany), 2167.01 (Wolf, Knittlingen, Germany), USL 2000 (Circon Corp., Santa Barbara, California) and an ultrasound prototype lithotriptor (EMS, Nyon, Switzerland).RESULTS All ultrasound lithotriptors achieved stone disintegration, which depended on the pressure used to apply ultrasound. Newer devices with modified technology provided better disintegration. CONCLUSIONS: All ultrasound devices are effective for lithotripsy. Changes in the ultrasound setup and integration of modern technical knowledge into ultrasound devices increase efficacy.     

In vitro and in vivo efficacy of a rifampin-loaded silicone catheter for the prevention of CSF shunt infections

Summary Infection of cerebrospinal fluid (CSF) shunts is one of the major complications associated with their use and is usually managed by shunt removal, temporary insertion of an external drainage and implantation of a new shunt system. We have evaluated the efficacy of a rifampin-loaded silicone ventricular catheter to prevent bacterial colonization and infection in vitro and in an animal model.On the basis of an incorporation process a rifampin-loaded catheter was developed which is capable of releasing rifampin in bacteriocidal concentrations for 60 days and more. In a stationary bacterial adherence assay usingS. epidermidis as test strain, the colonization resistance of the device was demonstrated.To assess the capability of the catheter to prevent CSF shunt infections, a rabbit model was developed which allowed the establishment of a reliable and reproducible CSF infection by implantation of silicone catheters into the ventricle and inoculatingS. epidermidis (minimal dose 10⁶ cfu) orS. aureus (minimal dose 10³ cfu). Rifampinloaded catheters (12 animals inoculated with S. epidermidis, 8 animals inoculated with S. aureus) were compared with non-loaded (14 animals inoculated with S. epidermidis, 19 animals inoculated with S. aureus) control catheters, and infection was documented by clinical, microbiological and histological methods.In contrast to the control group, none of the animals with rifampin-loaded catheters showed clinical signs of infection. Furthermore, in none of the materials obtained after sacrifice of the animals (catheter, brain tissue, CSF, blood) could the infecting bacteria be cultured, whereas in materials from animals with the unloaded catheter the infecting strains could always be cultured from the catheter and from surrounding brain tissue. The histological examination of catheter-adjacent tissue supported these findings.We conclude that a rifampin-loaded silicone ventricular catheter is capable of completely preventing bacterial colonization and infection by staphylococci as the main causative organisms in CSF shunt infections and should be further evaluated in clinical trials.