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Male Rabbits (male + rabbits)
Selected AbstractsPercutaneous toxicokinetic and repeated cutaneous contact studies with ethylene glycol monohexyl etherJOURNAL OF APPLIED TOXICOLOGY, Issue 5 2003Bryan Ballantyne Abstract Ethylene glycol monohexyl ether (EGHE; CAS no. 112-54-4) is a liquid industrial chemical with a potential for skin contact. The toxicokinetics of EGHE was investigated in Fischer 344 rats and New Zealand White rabbits by intravenous (i.v.) and 48-h occluded epicutaneous dosing. Given i.v. to male rats (2.5,25 mg kg,1) [14C]EGHE demonstrated ,rst-order kinetics. Carbon-14 was eliminated mainly in urine (68,74%) as metabolites, with no free EGHE. The plasma free EGHE concentration declined rapidly post-dosing and was not detectable by 8 h. Similar results were obtained for [14C]EGHE given i.v. to male rabbits in the dosage range 1,10 mg kg,1, except that the metabolism of EGHE was more rapid, with no free EGHE being detectable in plasma by 1 h post-dosing. After cutaneous dosing of male and female rats with 25 mg kg,1, there was rapid percutaneous absorption, with >95% of the radiochemical dose being recovered. Percutaneous bioavailability was >75%. Carbon-14 was excreted in urine (21,33%) to a lesser extent than by the i.v. route, and 14CO2 and volatiles accounted for 15,18%. Carbon-14 recovery was low from tissues and organs (0.39,0.46%), with no preferential accumulation. Extensive metabolism was indicated by the rapid decline in plasma free EGHE, with none being detectable by 48 h. Free EGHE was not present in urine, and urinary radioactivity was associated with up to seven metabolites. After cutaneous dosing of male and female rabbits (10 mg kg,1) ca. 75% of the dose was recovered, most 14C being in urine (58,60%). Urine radioactivity was associated with up to nine metabolite peaks, but no free EGHE. The toxicokinetic ,ndings indicate a signi,cant percutaneous absorption of EGHE across both rat and rabbit skin, which is rapidly and extensively metabolized, with renal excretion being the principal route of elimination of metabolites. A 9-day repeated skin contact study in the male and female New Zealand White rabbit, using a dosage range of 44,444 mg kg,1 day,1, did not show any evidence for percutaneous systemic toxicity. Copyright © 2003 John Wiley & Sons, Ltd. [source] Reduced introgression of the Y chromosome between subspecies of the European rabbit (Oryctolagus cuniculus) in the Iberian PeninsulaMOLECULAR ECOLOGY, Issue 20 2008A. GERALDES Abstract The role of the Y chromosome in speciation is unclear. Hybrid zones provide natural arenas for studying speciation, as differential introgression of markers may reveal selection acting against incompatibilities. Two subspecies of the European rabbit (Oryctolagus cuniculus) form a hybrid zone in the Iberian Peninsula. Previous work on mitochondrial DNA (mtDNA), Y- and X-linked loci revealed the existence of two divergent lineages in the rabbit genome and that these lineages are largely subspecies-specific for mtDNA and two X-linked loci. Here we investigated the geographic distribution of the two Y chromosome lineages by genotyping two diagnostic single nucleotide polymorphisms in a sample of 353 male rabbits representing both subspecies, and found that Y chromosome lineages are also largely subspecies-specific. We then sequenced three autosomal loci and discovered considerable variation in levels of differentiation at these loci. Finally, we compared estimates of population differentiation between rabbit subspecies at 26 markers and found a surprising bimodal distribution of FST values. The vast majority of loci showed little or no differentiation between rabbit subspecies while a few loci, including the SRY gene, showed little or no introgression across the hybrid zone. Estimates of population differentiation for the Y chromosome were surprisingly high given that there is male-biased dispersal in rabbits. Taken together, these data indicate that there is a clear dichotomy in the rabbit genome and that some loci remain highly differentiated despite extensive gene flow following secondary contact. [source] Altered expression of thin filament-associated proteins in hypertrophied urinary bladder smooth muscleNEUROUROLOGY AND URODYNAMICS, Issue 1 2006Anita S. Mannikarottu Abstract Aims Obstruction of the urinary bladder outlet induces detrusor smooth muscle (DSM) hypertrophy. The goal of this study was to determine whether the composition of thin filament-associated proteins, known to play important roles in cytoskeletal structure and/or the regulation of contraction, is altered in DSM during hypertrophy. Methods DSM hypertrophy was induced in male rabbits by partial ligation of the urethra. Sham-operated rabbits served as a control. Reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time PCR revealed a significant increase in the expression of mRNAs for basic (h1) calponin (CaP), and ,-isoform of tropomyosin (Tm) in hypertrophied DSM compared to controls. Western blotting and two-dimensional (2-D) gel electrophoresis showed enhanced expression of these proteins and also a significant increase in the expression of ,-non muscle and ,-smooth muscle actin in the DSM from obstructed bladders, while ,-actin remained constant. Results Enhanced expression of these proteins in the DSM from obstructed bladders was confirmed by immunofluorescence microscopy. Double immunostaining with Cap/Tm and ,/,-actin-specific antibodies showed co-localization of these proteins in myocytes. Colocalization of smooth muscle specific myosin and CaP to cytoplasmic filaments in cells dissociated from the hypertrophied DSM indicated that these cells are differentiated smooth muscle cells. Conclusions The change in the isoforms of actin, Cap, and Tm may be part of the molecular mechanism for bladder compensation in increased urethral resistance. Neurourol. Urodynam. © 2005 Wiley-Liss, Inc. [source] Dynamic contrast-enhanced MRI of muscle perfusion combined with MR angiography of collateral artery growth in a femoral artery ligation modelNMR IN BIOMEDICINE, Issue 8 2007Quido G. de Lussanet Abstract To assess the use of MRI for evaluating changes in muscle blood flow and number of collateral arteries, serial dynamic contrast-enhanced MRI (DCE-MRI) was combined with high-spatial-resolution contrast-enhanced MR angiography (MRA) in a peripheral ischemia model. The combined MRI (DCE-MRI and MRA) protocol was performed serially in 15 male rabbits at 2,h (day 0+), 7 days, and 21 days after femoral artery ligation. In the anterior tibial and soleus muscle, changes in resting muscle blood flow determined as the endothelial transfer coefficient (Ktrans) and arterial inflow delay from DCE-MRI and changes in the number of sub-millimeter sized collateral arteries as scored with MRA were measured. Directly after ligation, Ktrans in the anterior tibial muscle was reduced to 23% of that in the control limb, then recovered to 81% on day 7, and to 85 % on day 21. Ktrans in the soleus muscle recovered from a reduction to 63% on day 0+, to 85% on day 7, and to 90% on day 21. The number of collaterals around the ligated femoral artery increased from 1.1 on day 0+ to 4.2 on day 7, and 6.0 on day 21 in the ligated limb only. Combined DCE-MRI and MRA allows non-invasive serial monitoring of changes in muscle blood flow and growth of sub-millimeter sized collateral arteries in a rabbit femoral artery ligation model. Copyright © 2007 John Wiley & Sons, Ltd. [source] Morphology of Reproductive Organs, Semen Quality and Sexual Behaviour of the Male Rabbit Exposed to a Soy-containing Diet and Soy-derived Isoflavones during Gestation and LactationREPRODUCTION IN DOMESTIC ANIMALS, Issue 6 2009JR Cardoso Contents Placental and breastfeeding transfer of soy isoflavones are potential routes for animal and human exposure to phytoestrogens, and reproductive dysfunctions have been linked to early exposure to these compounds. So, the aim of this study was to investigate the effects of perinatal (intrauterine and lactational) exposure to soy-containing diet and soy-derived isoflavones on the reproductive parameters of male rabbits. For this purpose, 12 female rabbits were randomly assigned to receive: (1) a soy- and alfalfa-free diet (control diet); (2) a soy- and alfalfa-free diet supplemented with 10 mg/kg body wt/day of soy isoflavones; (3) a soy- and alfalfa-free diet supplemented with 20 mg/kg body wt/day of soy isoflavones; and (4) a diet containing 18% of soy meal, throughout gestation and lactation. Weight and morphology of the reproductive organs of some of the male offspring were evaluated at weaning (between days 29 and 31). The remaining males were placed on the control diet from weaning to adulthood (gestational and lactational exposure only). Sexual behaviour, semen quality and reproductive organs' morphology were evaluated after puberty. There were no significant differences in litter size and gestation duration between control and treatment groups. Perinatal exposure to soy-containing diet and soy isoflavones did not alter testis, epididymides, proprostate and prostate weight and gross morphology. After puberty, sexual behaviour and semen parameters did not differ significantly from the control group. These results indicate that intrauterine and lactational exposure to soy-containing diet and soy-derived isoflavones may not adversely affect reproductive development and function of male rabbits. [source] Continuous occurrence of both insufficient neovascularization and elevated vascular permeability in rabbit proximal femur during inadequate repair of steroid-associated osteonecrotic lesionsARTHRITIS & RHEUMATISM, Issue 10 2009Ge Zhang Objective To examine the features of the intraosseous vasculature, the size of the marrow stem cell pool (MSCP), and expression of vascular endothelial growth factor A (VEGF) during inadequate repair of steroid-associated osteonecrotic lesions in rabbits. Methods Steroid-associated osteonecrosis was induced in male rabbits. At 0, 1, 2, 4, and 6 weeks postinduction, vascularization and permeability indices were quantified by dynamic magnetic resonance imaging (MRI). In addition, the size of the MSCP in the hematopoietic and mesenchymal compartments was determined, and marrow mononuclear cells expressing specific surface markers for endothelial progenitor cells or periendothelial mural precursor cells were counted. At various time points after the rabbits were killed, the proximal femora were dissected to examine the intraosseous vasculature by angiography, histomorphometry, and ultramorphology. In addition, osteonecrotic lesion repair and marrow VEGF expression were evaluated. Results Lesion formation without repair was observed at 2 weeks after induction of steroid-associated osteonecrosis. Rabbits displaying destructive repair (DR+) and those displaying reparative osteogenesis (DR,) from 4 weeks to 6 weeks postinduction were identified. From week 2 to week 6, the vascularization index was significantly lower in DR+ rabbits compared with DR, rabbits, whereas the permeability index was significantly higher in DR+ rabbits compared with DR, rabbits. The features of the intraosseous vasculature determined by angiography, histomorphometry, and ultramorphology were consistent with those determined by dynamic MRI. The MSCP size and number of marrow mononuclear cells expressing specific surface markers were all significantly lower in DR+ rabbits than in DR, rabbits from week 1 to week 6. The increased VEGF expression at 2 weeks was maintained through week 6 in DR+ rabbits, whereas VEGF expression decreased in DR, rabbits from week 2 to week 6. Conclusion Continuous occurrence of both insufficient neovascularization and elevated vascular permeability is accompanied by a continuously low- level MSCP and uncontrolled VEGF expression during inadequate repair of steroid-associated osteonecrotic lesions. [source] Urethral in situ biocompatibility of new drug-eluting biodegradable stents: an experimental study in the rabbitBJU INTERNATIONAL, Issue 8 2009Andres Kotsar OBJECTIVE To assess the effect of drug-eluting properties on the degradation process and the biocompatibility of biodegradable drug-eluting urethral stents. MATERIALS AND METHODS Braided biodegradable 80 L/20D-PLGA (copolymer of polylactide and polyglycolide) stents with drug-eluting properties were used as the test material. The drugs analysed were indomethacin, dexamethasone and ciprofloxacine. 80 L/20D-PLGA stents without a drug coating served as controls. In all, 16 male rabbits were used and divided into four groups. The stents were inserted under general anaesthesia into the posterior urethra. After 1 month, the rabbits were killed and the urethra removed for histological and optic microscopy analyses. RESULTS Control stents and the dexamethasone-eluting stents degraded totally during the follow-up period. Conversely, in both indomethacin- and ciprofloxacine-eluting stent groups, the degradation process was significantly delayed and they induced an increase in epithelial hyperplasia. Histological analysis showed that all the stents induced eosinophilia, but there were no significant differences in the intensity of acute or chronic inflammatory reactions and fibrosis. CONCLUSIONS A drug-eluting capacity can be added to biodegradable stents. The addition of a drug influences the biodegradation time of PLGA urethral stents. Further studies are needed, to find the proper concentrations and releasing profiles of the drugs to achieve the desired bioactivity and biocompatibility properties. [source] Long-term biomechanical properties of rabbit cornea after photodynamic collagen crosslinkingACTA OPHTHALMOLOGICA, Issue 1 2009Gregor Wollensak Abstract. Purpose:, Photodynamic riboflavin/ultraviolet-A (UVA)-induced collagen cross-linking, which increases the biomechanical stiffness of the human cornea by about 300%, has been introduced recently as a possible treatment for progressive keratoconus. The present study was undertaken to evaluate the longterm biomechanical effects of this new cross-linking treatment as a necessary prerequisite to its clinical success. Methods:, The corneas of the left eyes of nine male rabbits were cross-linked. The contralateral eyes served as controls. After removal of the central 7 mm of the epithelium, the corneas were treated with the photosensitizer riboflavin and UVA irradiation for 30 mins with an irradiance of 3 mW/cm2 using a 370-nm UVA double diode. Groups of three animals were killed immediately after treatment and at 3 and 8 months, respectively. Biomechanical stress,strain measurements were performed using a microcomputer-controlled biomaterial tester on 4 × 10-mm corneal strips. Results:, Corneal thickness in the treated rabbit cornea was 408 ± 20 ,m. A constant and significant increase in ultimate stress (of 69.7,106.0%), Young's modulus of elasticity (of 78.4,87.4%) and a decrease in ultimate strain (of 0.57,78.4%) were found over a time period of up to 8 months after cross-linking treatment. Conclusions:, Riboflavin/UVA-induced collagen cross-linking leads to a longterm increase in biomechanical rigidity which remains stable over time. These data support our previous longterm clinical observations and give hope that this new treatment will halt progressive keratoconus definitively. [source] Immunoexpression of Cbfa-1/Runx2 and VEGF in sinus lift procedures using bone substitutes in rabbitsCLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2010Leandro Soeiro De Souza Nunes Abstract Objectives: To analyze and compare the expression of core binding factor-1 (Cbfa-1)/Runx2 and vascular endothelium growth factor (VEGF) in sinus lift procedures using bovine hydroxyapatite (HA) and ,-tricalcium phosphate (,-TCP). Material and Methods: Twenty-four male rabbits that had undergone bilateral sinus lift procedures were divided into three groups, according to the sinus filling material: Group 1: autogenous bone graft; Group 2: bovine HA; and Group 3: ,-TCP. All groups were sacrificed after 7, 14, 30 and 60 days, for microscopic, histomorphometry and immunohistochemistry analysis. Results: Microscopic analysis showed a similar bone repair pattern between the tested groups. New bone formation, soft and medular tissue, remaining material or particulate bone graft area were obtained by histomorphometric analysis. After 14 days, statistically significant differences in new bone formation were found between Group 1 (27.76±7.8) and Groups 2 (14.22±3.2) and 3 (11.1±7.7). After 30 days, statistically significant differences (P<0.05) were detected in bone formation between Groups 1 (31.39±36.5) and 2 (14.13±3.2). The last period showed improved bone formation in Group 2. Also, Group 2 showed higher Cbfa-1/Runx2 immunoexpression when compared with Group 3. No remarkable differences were observed in VEGF immunoexpression among groups. Conclusion: Taken together, both biomaterials allowed bone tissue growth in a conductive pattern and did not interfere with bone remodeling in the late period, with a slight improvement in bone tissue formation when using HA, confirmed by marked expression of Cbfa-1 at initial periods. To cite this article: Nunes LSS, De Oliveira RV, Holgado LA, Nary Filho H, Ribeiro DA, Matsumoto MA. Immunoexpression of Cbfa-1/Runx2 in sinus lift procedures using bone substitutes in rabbits. Clin. Oral Impl. Res. 21, 2010; 584,590. doi: 10.1111/j.1600-0501.2009.01858.x [source] | ||||||||||