New Zealand Rabbits (new + zealand_rabbits)

Distribution by Scientific Domains

Selected Abstracts

Effects of (,)-carveol and HPMC on the in vitro ocular transport and the in vivo intraocular pressure lowering effects of dorzolamide formulations in normotensive New Zealand rabbits

Mohsen I. Afouna
Abstract The objective of the current study was to maximize the ocular bioavailability of the carbonic anhydrase inhibitor, dorzolamide hydrochloride (DZD) via (a) enhancement of DZD corneal transport using terpene enhancers, (b) reducing pre-corneal loss of the installed dose via increased formulation viscosity, and (c) assessment of the in vivo intraocular pressure (IOP) lowering effects of test formulations using rabbit. DZD was formulated as a 2% ophthalmic solution containing different concentrations of HPMC as a viscosity improving agent (VIA), and (,)-carveol as a corneal penetration enhancer. The transport of DZD from test formulations was quantitatively determined using in vitro diffusion experiments, the permeability parameters were mathematically calculated, and the in vivo IOP lowering effects were assessed using a Tono-Pen XL® tonometer. The results revealed a good correlation between the in vitro permeability parameters and the in vivo ,IOP. The magnitude of the DZD-IOP lowering effects and durations of actions for DZD formulations were dependent on (a) the concentration of (,)-carveol, and (b) the contact period with ocular tissue which was found to be a single-valued function of the HPMC as VIA. Drug Dev Res 70, 2009. © 2009 Wiley-Liss, Inc. [source]

In vivo evaluation of hydroxyapatite foams

P. Sepulveda
Abstract Hydroxyapatite (HA) is widely applied as bone graft material due to its osteoconductive potential and well-established biocompatibility. In this work, macroporous hydroxyapatite structures made through foaming of aqueous suspensions and gelcasting were tested for in vivo osteointegration. These foams are composed of a three-dimensional array of spherical pores with diameters of approximately 100,500 ,m, interconnected by windows of smaller size in the range of 30,120 ,m. The HA foams were implanted in the tibia of albino New Zealand rabbits and removed after a period of 8 weeks. Histological analysis revealed that the pores in the foams were partially or completely filled progressively with mature new bone tissue and osteoid after the implanted period. No immune or inflammatory reactions were detected. The high osteoconductive potential of the HA foams provides a potential structure for use as bone substitute in orthopedic, oral, and cranio-maxillofacial reconstructive surgery, and as dento-alveolar implants. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 587,592, 2002 [source]

Supraspinatus tendon repair into a bony trough in the rabbit: Mechanical restoration and correlative imaging

Guy Trudel
Abstract Recurrence of tears is a common complication after rotator cuff surgery. Retearing seems to occur early after surgery and may be attributed to too early or too vigorous exercises. We found no experimental data correlating the strength of the rotator cuff early after surgery and imaging. Our objectives were to measure the peak load to failure of rabbit supraspinatus tendon,bone constructs at early times postoperatively, to determine their mode of failure, and to determine whether computed tomography (CT) can predict their strength. We divided one supraspinatus tendon of 40 adult female white New Zealand rabbits and, after resection of the enthesis, sutured the tendon into a bony trough. Ten rabbits were killed immediately and 10 each at 1, 2, and 6 weeks postoperatively. The explanted tendons of both shoulders were imaged on CT and tested to failure. Compared to normal tendons (mean 210,±,42 N), the mean strength was very low at 0 weeks (57,±,21 N) and 1 week (86,±,33 N) (both p,<,0.05); it had recovered by 6 weeks (324,±,66 N). Early on, suture pullout was the most common mode of failure, whereas at 6 weeks, mid-substance tears predominated (p,<,0.05). Hypoattenuation on CT was associated with increased strength of the tendon,bone construct (p,<,0.05). The strength of the surgical construct is very low in the early postoperative period. Therefore, the shoulder should be submitted only to loads not interfering with healing. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:710,715, 2010 [source]

Pharmacokinetic-pharmacodynamic integration of moxifloxacin in rabbits after intravenous, intramuscular and oral administration

The pharmacokinetics of moxifloxacin was studied following intravenous (i.v.), intramuscular (i.m.) and oral dose of 5 mg/kg to healthy white New Zealand rabbits (n = 6). Moxifloxacin concentrations were determined by HPLC assay with fluorescence detection. The moxifloxacin plasma concentration vs. time data after i.v. administration could best be described by a two-compartment open model. The disposition of i.m. and orally administered moxifloxacin was best described by a one-compartment model. The plasma moxifloxacin clearance (Cl) for the i.v route was (mean ± SD) 0.80 ± 0.02 L/h·kg. The steady-state volume of distribution (Vss) was 1.95 ± 0.18 L/kg. The terminal half-life (t1/2,z) was (mean ± SD) 1.84 ± 0.12, 2.09 ± 0.05 and 2.15 ± 0.07 h after i.v., i.m. and oral, respectively. Minimal inhibitory concentration (MIC) assays of moxifloxacin against different strains of S. aureus were performed in order to compute pharmacodynamic surrogate markers. From these data, it is concluded that a 5 mg/kg dose moxifloxacin would be effective by i.m. and oral routes in rabbits against bacterial isolates with MIC , 0.06 ,g/mL and possibly for MIC , 0.12 ,g/mL, but in the latter case a higher dose would be required. [source]

Effects of sodium benzoate on the complications of 1.

5% glycine solution using two different intravesical pressures during bladder irrigation
Background:, In this experimental study we researched the effects of sodium benzoate on the complications of 1.5% glycine solution using with two different intravesical pressures during bladder irrigation. Methods:, Thirty-six male adult New Zealand rabbits with body weight ranging from 1500 to 2800 g were used in the experiments. The rabbits were randomly allocated to four groups. In groups 1 and 2, 500 ml of 1.5% gylcine was used as irrigating fluid during 30 min, but only group 2 received 500 mg kg,1 of sodium benzoate treatment by oral route immediately after irrigation. In groups 3 and 4, 500 ml of 1.5% glycine was used as irrigating fluid during 60 min, but only group 4 received the same treatment as group 2. Ammonia, urea, sodium, potassium, hemoglobin, hemotocrit and platelet levels were studied at preirrigation and postirrigation on the 4 h and 24 h. Also electrocardiographic (ECG) changes were monitored at the same time with blood parameters. Results:, At 4 h postirrigation, Na+ levels were decreased significantly in group 1 and non-significantly in group 3 when compared with preirrigation levels. But these levels were not changed in groups 2 and 4. Both at 4 h and 24 h, ammonia and urea levels were significantly increased in groups 1 and 3. Ammonia level was decreased but the urea level was not changed in groups 2 and 4 at the same time points. K+ level was significantly changed only in group 1 at 4 h and 24 h. Hemoglobin and hemotocrit concentrations were decreased both at 4 h and 24 h compared with preirrigation levels in all groups. Also there were ECG changes between the treated and untreated groups. Conclusion:, Sodium benzoate was very effective against the complications of 1.5% glycine during bladder irrigation experimentally. But this needs further investigation, especially for the applicability of this new treatment model in human TURP syndrome. [source]

Injection of Embryonic Stem Cells Into Scarred Rabbit Vocal Folds Enhances Healing and Improves Viscoelasticity: Short-Term Results,

Jessica Cedervall MSc
Abstract Objectives: Scarring caused by trauma, postcancer treatment, or inflammation in the vocal folds is associated with stiffness of the lamina propria and results in severe voice problems. Currently there is no effective treatment. Human embryonic stem cells (hESC) have been recognized as providing a potential resource for cell transplantations, but in the undifferentiated state, they are generally not considered for therapeutic use due to risk of inadvertent development. This study assesses the functional potential of hESC to prevent or diminish scarring and improve viscoelasticity following grafting into scarred rabbit vocal folds. Study Design: hESC were injected into 22 scarred vocal folds of New Zealand rabbits. After 1 month, the vocal folds were dissected and analyzed for persistence of hESC by fluorescence in situ hybridization using a human specific probe, and for differentiation by evaluation in hematoxylin-eosin-stained tissues. Parallel-plate rheometry was used to evaluate the functional effects, i.e., viscoelastic properties, after treatment with hESC. Results: The results revealed significantly improved viscoelasticity in the hESC-treated vs. non-treated vocal folds. An average of 5.1% engraftment of human cells was found 1 month after hESC injection. In the hESC-injected folds, development compatible with cartilage, muscle and epithelia in close proximity or inter-mixed with the appropriate native rabbit tissue was detected in combination with less scarring and improved viscoelasticity. Conclusions: The histology and location of the surviving hESC-derived cells strongly indicate that the functional improvement was caused by the injected cells, which were regenerating scarred tissue. The findings point toward a strong impact from the host microenvironment, resulting in a regional specific in vivo hESC differentiation and regeneration of three types of tissue in scarred vocal folds of adult rabbits. [source]

Viscoelastic and Histologic Properties in Scarred Rabbit Vocal Folds After Mesenchymal Stem Cell Injection,

S Hertegård MD
Abstract Objective/Hypothesis: The aim of this study was to analyze the short-term viscoelastic and histologic properties of scarred rabbit vocal folds after injection of human mesenchymal stem cells (MSC) as well as the degree of MSC survival. Because MSCs are antiinflammatory and regenerate mesenchymal tissues, can MSC injection reduce vocal fold scarring after injury? Study Design: Twelve vocal folds from 10 New Zealand rabbits were scarred by a localized resection and injected with human MSC or saline. Eight vocal folds were left as controls. Material and Methods: After 4 weeks, 10 larynges were stained for histology and evaluation of the lamina propria thickness. Collagen type I content was analyzed from six rabbits. MSC survival was analyzed by fluorescent in situ hybridization staining from three rabbits. Viscoelasticity for 10 vocal folds was analyzed in a parallel-plate rheometer. Results: The rheometry on fresh-frozen samples showed decreased dynamic viscosity and lower elastic modulus (P < .01) in the scarred samples injected with MSC as compared with the untreated scarred group. Normal controls had lower dynamic viscosity and elastic modulus as compared with the scarred untreated and treated vocal folds (P < .01). Histologic analysis showed a higher content of collagen type 1 in the scarred samples as compared with the normal vocal folds and with the scarred folds treated with MSC. MSCs remained in all samples analyzed. Conclusions: The treated scarred vocal folds showed persistent MSC. Injection of scarred rabbit vocal folds with MSC rendered improved viscoelastic parameters and less signs of scarring expressed as collagen content in comparison to the untreated scarred vocal folds. [source]


Ali Ayyildiz
Aim: To investigate long-term histological features of bladder augmentation using porcine small intestine submucosa (SIS) in a rabbit model. Materials and method: Sixteen New Zealand rabbits were used. Porcine SIS was provided by a manufactured formation derived from the pig. After partial cystectomy was carried out on the bladder, a single layer of SIS (Cook® -SIS Technology, Cook Biotech Incorporated, West Lafayette, IN, USA) (2 × 5 cm) was sewn to bladder with continuous 5/0 vicryl suture material in a watertight manner. Urinary diversion was not used. The rabbits were killed 12 months later and perivesical fat was removed together with bladder. The 5-,m preparations taken from the samples were stained with haematoxylin,eosin and Mason's trichrome dye. S-100 and F8 stains were also used for immunohistochemical investigations. Results: The macroscopic view of bladder was normal. SIS was indistinguishable from normal bladder wall, but the region of the graft had a slight white coloration. Microscopic observations showed the continuity of transitional epithelium of host bladder tissue on SIS material. Detrusor and serosal layers were formed and these layers were indistinguishable from host bladder. Fibroblasts were scattered among the collagen fibrils. New vessel formations were present without lymphatic proliferation. Nerve regeneration was excellent. No inflammation was observed in normal and regenerated bladder wall. Conclusion: At the end of 12 months, the long-term histological features of bladder augmentation with porcine SIS in a rabbit model, such as presence of new vessel formations, nerve regeneration, collagen and smooth muscle regenerations, which were indistinguishable from original bladder, and the absence of inflammation, showed that SIS seems to be a viable alternative to the use of intestine in bladder augmentation. [source]

Fabrication of Myomucosal Flap Using Tissue-engineered Bioartificial Mucosa Constructed With Oral Keratinocytes Cultured on Amniotic Membrane

Kang-Min Ahn
Abstract:, The purpose of this study was to fabricate bioartificial mucosa using cultured oral keratinocytes (OKCs) on an amniotic membrane (AM), and to evaluate the possibility of developing a prelaminated myomucosal flap using the fabricated bioartificial mucosa and local muscle flap. Buccal mucosa was harvested from male New Zealand rabbits (n = 40, 2.5,3.0 kg) and primary cultivation was performed. The cultured OKCs were seeded on the AM and a submerged culture was performed. Prelamination of the bioartificial mucosa was performed on the latissimus dorsi (LD) muscle of rabbits. Survival rate, layer of OKCs, and Cinamon's score (CS) based on macroscopic and microscopic examinations were evaluated 7, 10, 14, and 21 days after prelamination (n = 10 per day). The OKCs cultured on AM showed multiple layers (3.85 ± 1.32) and cells were tightly adhered with desmosomes. Basal layer cells adhered to the AM with hemidesmosomes. In addition, the AM played an excellent role as a substrate for the OKCs and simplified handling during prelamination. A myomucosal flap with OKCs cultured on AM was fabricated within 2 weeks (CS: 11.05 ± 2.63). The basement component of laminin was observed 2 weeks after prelamination and showed enough strength to adhere to the underlying fascia. A myomucosal flap was successfully developed using prelamination of bioartificial mucosa on the LD muscle between 10 and 14 days. [source]

Tissue reaction of the rabbit urinary bladder to tension-free vaginal tape and porcine small intestinal submucosa

D.M. Rabah
Objectives ,To compare the histological tissue reactions of urinary bladder in close contact with polypropylene mesh tension-free vaginal tape (TVT) or porcine small intestinal submucosal (SIS) grafts, as the commercial availability of various materials has considerably simplified sling procedures for treating urinary incontinence, but erosion and infection after using artificial sling materials remain an important concern. Materials and methods ,Thirty female New Zealand rabbits were randomized to three groups, i.e. group A (TVT, 12 animals), group B (SIS, 12) and group C (surgical control, six). Through a laparotomy under anaesthesia and an aseptic technique, the bladder was approached at its dome, where a 0.5 × 1 cm piece of TVT or SIS was fixed in direct contact with the bladder wall. The control group underwent only bladder manipulation with no material applied. Half the animals in each group were killed after 6 weeks and the other half after 12 weeks. The urinary bladder was harvested and examined histologically. Results ,The grafts in both groups were characterized by dense foreign-body type reactions and were mostly attached loosely to the bladder wall by a thin layer of fibrovascular tissue. More importantly, the bladder wall reactions showed no inflammation in all 12 animals in group A (TVT) but three of them had various grades of fibrosis. There was severe transmural inflammation in one animal in group B (SIS); one rabbit had grade I and two had grade II fibrosis. The controls, as expected, showed no bladder wall reactions. Conclusion ,In this descriptive analysis of reaction types elicited on the urinary bladder by these grafts, both materials appeared to be safe. Although TVT elicited fewer and less severe adverse reactions, no statistical conclusions can be drawn. The clinical significance of these findings should emerge from long-term clinical data when they become available. [source]

Tolerance and safety of ocular use of recombinant human erythropoietin (rhEPO).

Neuroprotective effects in ocular hypertension/glaucoma
Purpose The purpose of this study was to evaluate the long-term effects of monthly intravitreal injections of rhEPO in a rabbit model. Methods Sixteen New Zealand rabbits were divided into 4 groups: control (no injection), saline injection, or rhEPO injections of 500 U and 1000 U (N=4 per group). The right eye of each animal was injected monthly over a period of 7 months. Fundus examination and electroretinography (ERG) were performed at 1 day prior, and 1 week, 1 month, and 6 months after the initial injection. After the final ERG, animals underwent fluorescein angiography and sacrifice one week later. Scotopic and photopic ERG amplitude and implicit times were analyzed by calculating a ratio between the right and the left eyes. Angiograms were graded for the presence of neovascularization or leakage. Statistical analysis was carried out using two-way ANOVA. Results Fifteen animals were used for this experiment (1 developed a traumatic cataract and was excluded). Between all groups and time points, there were no statistically significant differences in the computed right eye:left eye ratios for the scotopic or photopic ERG components (p>0.05). No evidence of neovascularization or fluorescein leakage was seen on angiography. There were no visible differences in retinal architecture or thickness in the rhEPO groups when compared to uninjected controls. Conclusion Monthly 0.1 ml intravitreal injections of rhEPO at a dose of up to 1000 U over 7 months is well-tolerated and does not cause adverse effects on retinal function, architecture, or vasculature in a rabbit model. A review of published data on rhEPO and Glaucoma will also be presented. [source]

Osseointegration of titanium alloy and HA-coated implants in healthy and ovariectomized animals: a histomorphometric study

Guaracilei Maciel Vidigal Jr
Abstract Objectives: The objective of the present study is to evaluate the response to dental implants in healthy and osteoporotic bone. Materials and methods: Ten ovariectomized (OVX) New Zealand rabbits submitted to a hypocalcic diet and 10 sham-aged rabbits were used. All animals were submitted to bone mineral density (BMD) measurements before ovariectomy, and also 4 months afterwards, using dual energy X-ray absorptiometry. The BMD measurements showed a significant loss of bone mass, between the first and second examinations, only in the experimental group (P<0.05). After the bone mass loss induction period, three different implants were installed in the proximal tibia metaphisis of each animal: a titanium alloy implant (Ti), a plasma-spray hydroxyapatite-coated implant (HA-PS), and another implant coated with hydroxyapatite with the biomimetic process (HA-B). Results: After 3 months, histomorphometry showed a bone-to-implant contact (BIC) for Ti implants of 73.09±13.74% in healthy and 66.09±30.01% in OVX animals. The BIC for the HA-PS was 64.83±15.65% and 90.17±8.14% for healthy and OVX animals, respectively, and 88.66±5.30% and 87.96±10.71% for the HA-B implants placed in the same conditions. The differences between the implants in healthy and OVX conditions were not statistically significant (P>0.05). The only significant difference within groups was observed in the healthy animals between HA-B and Ti implants (P<0.06). Conclusion: Within the parameters used in this animal model it was not possible to observe BIC differences between osteoporotic and healthy animals. [source]