scholarly journals Biocompatibility and feasibility of VisiPlate, a novel ultrathin, multichannel glaucoma drainage device

2021 ◽  
Vol 32 (12) ◽  
Author(s):  
Brandon W. Kao ◽  
Elana Meer ◽  
Thomas A. Barbolt ◽  
Richard A. Lewis ◽  
Iqbal Ike Ahmed ◽  
...  
Keyword(s):  
Microelectromechanical Systems ◽  
Rabbit Model ◽  
Tissue Response ◽  
Glaucoma Drainage Device ◽  
Slit Lamp ◽  
Parylene C ◽  
Clinical Observations ◽  
Contralateral Eye ◽  
The Right

Abstract Background Glaucoma is the leading cause of blindness worldwide. Glaucoma drainage devices and minimally invasive glaucoma surgeries (MIGS) often present with tradeoffs in safety and durability of efficacy. Using a rabbit model, we examined the biocompatibility and feasibility of VisiPlate, a novel, ultrathin, tubeless subconjunctival shunt comprised of a network of microchannels. Methods Six naive female New Zealand White rabbits received implants (three only in the right eye with contralateral eye untreated and three in both eyes) composed of a 400-nm-thick aluminum oxide core coated with 2 µm of parylene-C, manufactured with microelectromechanical systems (MEMS) techniques. Tonometry, slit lamp exam, clinical exam, fluorescein patency testing, and histopathology were performed. Results VisiPlate demonstrated IOP-lowering of 20–40% compared to baseline at each time point over the course of 3 months in the nine implanted eyes. All eyes developed blebs over the implant, and fluorescein testing demonstrated fluid patency at 22 days post-implantation. Slit lamp and clinical observations showed that VisiPlate was well tolerated, with low levels of conjunctival congestion, conjunctival swelling, aqueous flare, hyphema, and iris involvement from surgery that resolved over time. At sacrifice time points of 93 days and 180 days, the only notable observations were mild levels of conjunctival congestion in implanted eyes. Histopathology showed minimal tissue response and no obvious inflammation, fibrosis, or necrosis around the implant. Conclusions The results of this in vivo study demonstrate the biocompatibility and IOP-lowering effect of a multichannel, ultrathin subconjunctival shunt in a rabbit model. The data suggest that VisiPlate may safely enhance aqueous outflow and significantly reduce intraocular pressure.

scholarly journals Enhanced release of calcium phosphate additives from bioresorbable orthopaedic devices using irradiation technology is non-beneficial in a rabbit model

2019 ◽  
Vol 8 (6) ◽  
pp. 266-274
Author(s):  
I. Palmer ◽  
S. A. Clarke ◽  
F. J Buchanan
Keyword(s):  
Calcium Phosphate ◽  
Bone Repair ◽  
Bone Growth ◽  
Calcium Release ◽  
Release Kinetics ◽  
Rabbit Model ◽  
Tissue Response ◽  
Ph Change ◽  
Irradiation Technology

Objectives Bioresorbable orthopaedic devices with calcium phosphate (CaP) fillers are commercially available on the assumption that increased calcium (Ca) locally drives new bone formation, but the clinical benefits are unknown. Electron beam (EB) irradiation of polymer devices has been shown to enhance the release of Ca. The aims of this study were to: 1) establish the biological safety of EB surface-modified bioresorbable devices; 2) test the release kinetics of CaP from a polymer device; and 3) establish any subsequent beneficial effects on bone repair in vivo. Methods ActivaScrew Interference (Bioretec Ltd, Tampere, Finland) and poly(L-lactide-co-glycolide) (PLGA) orthopaedic screws containing 10 wt% β-tricalcium phosphate (β-TCP) underwent EB treatment. In vitro degradation over 36 weeks was investigated by recording mass loss, pH change, and Ca release. Implant performance was investigated in vivo over 36 weeks using a lapine femoral condyle model. Bone growth and osteoclast activity were assessed by histology and enzyme histochemistry. Results Calcium release doubled in the EB-treated group before returning to a level seen in untreated samples at 28 weeks. Extensive bone growth was observed around the perimeter of all implant types, along with limited osteoclastic activity. No statistically significant differences between comparative groups was identified. Conclusion The higher than normal dose of EB used for surface modification did not adversely affect tissue response around implants in vivo. Surprisingly, incorporation of β-TCP and the subsequent accelerated release of Ca had no significant effect on in vivo implant performance, calling into question the clinical evidence base for these commercially available devices. Cite this article: I. Palmer, S. A. Clarke, F. J Buchanan. Enhanced release of calcium phosphate additives from bioresorbable orthopaedic devices using irradiation technology is non-beneficial in a rabbit model: An animal study. Bone Joint Res 2019;8:266–274. DOI: 10.1302/2046-3758.86.BJR-2018-0224.R2.

scholarly journals Understanding and Recognition of the Right Ventricular Function and Dysfunction: A Numerical Study

2020 ◽  
Author(s):  
Giulia Comunale ◽  
Paolo Peruzzo ◽  
Biagio Castaldi ◽  
Renato Razzolini ◽  
Giovanni Di Salvo ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Right Ventricular ◽  
Numerical Study ◽  
Hemodynamic Parameters ◽  
Right Heart ◽  
Clinical Observations ◽  
Lumped Parameter ◽  
The Right ◽  
First Time

Abstract The role played by the right ventricular (RV) dysfunction has long been underestimated in clinical practice. Recent findings are progressively confirming that when the RV efficiency deteriorates both the right and the left circulation is (significantly) affected, but studies dedicated to a detailed description of RV hemodynamic role still lack. In response to such a gap in knowledge, this work proposes a numerical model that for the first time evaluates the effect of isolated RV dysfunction on the whole circulation. Lumped parameter modelling was applied to represent the physio-pathological hemodynamics. Different grades of impairment were simulated for three dysfunctions i.e., systolic, diastolic, and combined systolic and diastolic. Hemodynamic alterations (i.e., of blood pressure, flow, global hemodynamic parameters), arising from the dysfunctions, are calculated and analysed. Results well accord with clinical observations, showing that RV dysfunction significantly affects both the pulmonary and systemic hemodynamics. Successful validation against in vivo data proved the clinical potentiality of the model i.e., the capability of identifying the degree of RV impairment for given hemodynamic conditions. This study aims at contributing to the improvement of RV dysfunction recognition and treatment, and to the development of tools for the clinical management of pathologies involving the right heart.

Dimethylthiourea does not ameliorate reperfusion lung injury in dogs or rabbits

1988 ◽  
Vol 65 (5) ◽  
pp. 2051-2056 ◽  
Author(s):  
M. J. Bishop ◽  
E. Y. Chi ◽  
M. Su ◽  
F. W. Cheney
Keyword(s):  
Hydroxyl Radical ◽  
Rabbit Model ◽  
Left Lung ◽  
Treated Group ◽  
Lung Edema ◽  
Activated Neutrophils ◽  
Pulmonary Arterial ◽  
Species Specific ◽  
The Right

We previously demonstrated that in vivo reperfusion of a dog lung after 48 h of pulmonary arterial (PA) ischemia results in pulmonary edema with a significant infiltrate of polymorphonuclear leukocytes. We hypothesized that the injury resulted from production of hydroxyl radical by activated neutrophils. In the current study, we attempted to prevent the injury in both dogs and rabbits with dimethylthiourea (DMTU), a scavenger of hydroxyl radical. After 48 h of left PA occlusion in 18 dogs, DMTU was administered to 9 animals and 9 were not treated. The occlusion was then released, and the dogs were killed 4 h later. Reperfusion resulted in a drop in leukocyte count and left lung edema, but there was no difference between treated and untreated animals. The wet-to-dry ratios of the lungs in the treated group were 5.76 +/- 0.44 (SE) on the reperfused left side and 4.50 +/- 0.06 (P less than 0.05) on the right side. In the untreated groups the comparable ratios were 5.73 +/- 0.31 and 4.92 +/- 0.10 (P less than 0.05 for right vs. left). Histological examination revealed significant differences between the right and left lungs in the extent of intra-alveolar granulocytes and macrophages but did not reveal differences between the treated and untreated animals. To ensure that neither the model nor the lack of response to DMTU was species specific, we then developed a rabbit model of reperfusion edema.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Effect of Novel Design Modifications on Fibrotic Encapsulation: An In Vivo Glaucoma Drainage Device Study in a Rabbit Model

2020 ◽  
Vol 9 (2) ◽  
pp. 279-291 ◽  
Author(s):  
Nathan A. Fischer ◽  
Malik Y. Kahook ◽  
Suhail Abdullah ◽  
Eric Porteous ◽  
David A. Ammar ◽  
...  
Keyword(s):  
Rabbit Model ◽  
Glaucoma Drainage Device ◽  
Drainage Device ◽  
Novel Design

Reactions of bone, liver and kidney tissues to orthopaedic implants with silver nanoparticle doped hydroxyapatite coatings: microscopic examination in a rabbit model

2018 ◽  
Vol 87 (2) ◽  
pp. 99-105
Author(s):  
Łukasz Łapaj ◽  
Waldemar Woźniak ◽  
Paweł Chodór ◽  
Jan Zabrzyński ◽  
Łukasz Paczesny
Keyword(s):  
Biofilm Formation ◽  
Structural Changes ◽  
Rabbit Model ◽  
Fatty Degeneration ◽  
Tissue Response ◽  
Orthopaedic Implants ◽  
Toxic Reaction ◽  
Joint Infections ◽  
Liver And Kidney

Background: Periprosthetic joint infections are severe complications of arthroplasty, difficult to manage due to biofilm formation on the components. Recently, the use of silver nanoparticles (SNs) has emerged as a method of preventing biofilm formation on orthopaedic implants, however little is known about the systematic toxicity of SNs.Aim: This study used a rabbit model to examine the tissue response of bone, liver and kidney to prototype components with SN doped hydroxyapatite (HA) coatings.Materials and methods: Twelve prototype implants (six with HA, six with SN doped HA coatings) were implanted into the femora of twelve New Zealand Rabbits. After 6 weeks, the animals were euthanised, their femora and samples of livers and kidneys harvested to prepare microscopic slides. The slides were examined for the presence inflammatory or toxic reactions to SNs, implants were examined using scanning electron microscopy (SEM) to determine structural changes related to implantation and verify retention of SNs in vivo.Results: SEM demonstrated that SNs formed submicron conglomerates, which were retained after 6 weeks in vivo and did not interfere with osseointegration. Histologic studies of bone fragments demonstrated no signs of acute toxicity and inflammation. No inflammatory reaction was observed in kidneys, although in some samples signs of acute renal failure related to euthanasia were found. No severe toxic reaction was found in liver samples, however fatty degeneration of liver was found in some animals.Conclusions: This study documented good osteointegration of implants with SN doped HA coatings with low systematic toxicity of SNs.

scholarly journals Biocompatible Hydrogel for Intra-Articular Implantation Comprising Cationic and Anionic Polymers of Natural Origin: In Vivo Evaluation in a Rabbit Model

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4426
Author(s):  
Karina L. Bierbrauer ◽  
Roxana V. Alasino ◽  
Fernando E. Barclay ◽  
Eduardo M. Belotti ◽  
Hugo H. Ortega ◽  
...  
Keyword(s):  
Cruciate Ligament ◽  
Cartilage Damage ◽  
Rabbit Model ◽  
Left Knee ◽  
In Vivo Studies ◽  
In Vivo Evaluation ◽  
Group A ◽  
Group B ◽  
The Right

We describe the functional capability of a cross-linked hydrogel composed of sulfated glycosaminoglycans and a cationic cellulose by conducting trials on experimental animal models using intra-articular implants to treat an articular disease called osteoarthritis. Forty-eight mature New Zealand white rabbits were divided into three experimental groups: A, B, and C. Group A and B underwent unilateral anterior cruciate ligament transection (ACLT) of the right knee. Subsequently, both knees of group A were treated with the injectable formulation under study. Meanwhile, group B was treated with sterile PBS (placebo). The animals of group C were surgically operated in both knees: Commercial hyaluronic acid (HA) was implanted in the left knee, and the formulation under study was implanted in the right knee. After implantation, all specimens underwent several evaluations at 3, 6, and 12 months postoperatively. At 6 months, no significant differences were detected between the right and left knees of the different groups. However, significant differences were observed between both knees at 12 months in group C, with less cartilage damage in the right knees implanted with our hydrogel. Therefore, in vivo studies have demonstrated hydrogel safety, superior permanence, and less cartilage damage for long-term follow up 12 months after implantation for the formulation under study compared with commercial HA.

scholarly journals Understanding and recognition of the right ventricular function and dysfunction via a numerical study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Giulia Comunale ◽  
Paolo Peruzzo ◽  
Biagio Castaldi ◽  
Renato Razzolini ◽  
Giovanni Di Salvo ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Right Ventricular ◽  
Numerical Study ◽  
Hemodynamic Parameters ◽  
Right Heart ◽  
Clinical Observations ◽  
Lumped Parameter ◽  
The Right ◽  
First Time

AbstractThe role played by the right ventricular (RV) dysfunction has long been underestimated in clinical practice. Recent findings are progressively confirming that when the RV efficiency deteriorates both the right and the left circulation is (significantly) affected, but studies dedicated to a detailed description of RV hemodynamic role still lack. In response to such a gap in knowledge, this work proposes a numerical model that for the first time evaluates the effect of isolated RV dysfunction on the whole circulation. Lumped parameter modelling was applied to represent the physio-pathological hemodynamics. Different grades of impairment were simulated for three dysfunctions i.e., systolic, diastolic, and combined systolic and diastolic. Hemodynamic alterations (i.e., of blood pressure, flow, global hemodynamic parameters), arising from the dysfunctions, are calculated and analysed. Results well accord with clinical observations, showing that RV dysfunction significantly affects both the pulmonary and systemic hemodynamics. Successful verification against in vivo data proved the clinical potentiality of the model i.e., the capability of identifying the degree of RV impairment for given hemodynamic conditions. This study aims at contributing to the improvement of RV dysfunction recognition and treatment, and to the development of tools for the clinical management of pathologies involving the right heart.

Evaluation of 99mTc-Label led Vitamin K4 as an Agent for Testicular Imaging

1991 ◽  
Vol 30 (01) ◽  
pp. 35-39 ◽  
Author(s):  
H. S. Durak ◽  
M. Kitapgi ◽  
B. E. Caner ◽  
R. Senekowitsch ◽  
M. T. Ercan
Keyword(s):  
Soft Tissue ◽  
Room Temperature ◽  
Normal Subjects ◽  
Left Testis ◽  
Wide Range ◽  
Activity Ratios ◽  
The Right ◽  
Radioactivity Levels

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 ±9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 ±6.3% as determined by TCA precipitation. Blood clearance of 99mTc-l<4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 ±0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection.99mTc-l<4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.

Acyl-Enzymes as Thrombolytic Agents in a Rabbit Model of Venous Thrombosis

1982 ◽  
Vol 47 (03) ◽  
pp. 269-274 ◽  
Author(s):  
R A G Smith ◽  
R J Dupe ◽  
P D English ◽  
J Green
Keyword(s):  
Venous Thrombosis ◽  
Active Site ◽  
Fibrinolytic Activity ◽  
Rabbit Model ◽  
Fibrinolytic Agent ◽  
Essential Nature ◽  
Thrombolytic Agents

SummaryA derivative of human lys-plasmin in which the active site has been reversibly acylated (BRL 26920; p-anisoyl human lys-plasmin) has been examined as a fibrinolytic agent in a previously described rabbit model of venous thrombosis and shown to be significantly more active and less fibrinogenolytic than free plasmin. A p-anisoylated derivative of a streptokinase (SK)-activated plasmin preparation was significantly less fibrinogenolytic in vivo than the non-acylated enzyme. Acylation increased the fibrinolytic activity of preparations of SK-plasmin activator complexes. BRL 26921, the active site anisoylated derivative of the primary 2-chain SK-plasminogen complex was the most potent fibrinolytic agent studied. SK-Val442-plasminogen complexes, free or acylated, were biologically inactive in this model and confirm the essential nature of fibrin binding processes for effective thrombolysis in vivo.

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