The effect of L-NAME administrations after oral mucosal incision on wound NO level in rabbit

The aim of the current study was to comparatively investigate the effect of inhibition of nitric oxide (NO) production by N-nitro-L-arginine methyl ester (L-NAME), an isoform non-specific inhibitor of nitric oxide synthase (NOS), after oral mucosal incision on wound tissue NO levels. A standard incision was applied to the oral mucosa of rabbits. After oral mucosal incision, rabbits were divided into five groups as follows: (1) Untreated incisional group (control); (2) Titanium (Ti) implanted group; (3) Ti + Polyethylene glycol (PEG) 4000 implanted group; (4) Ti + PEG 4000 + L-NAME (2 × 10⁻⁴ M) implanted group and (5) i.p. L-NAME administrated group (10 mg/kg). At 5 days after oral incision operations, wound tissue strips and plasma were obtained from rabbits. Oral wound tissue and plasma nitric oxide, plasma thiobarbituric acid reactive substances (TBARS) and total sulfhydryl group (RSH) levels were investigated. Plasma TBARS and NOx levels decreased after i.p. L-NAME administration. Total RSH group levels were not changed in all groups (p>0.05). This means that L-NAME inhibits the deteriorating effects of free radicals without affecting healing. L-NAME in PEG and titanium also has no effect on tissue and plasma NOx levels. These findings indicate that NO generation will not be affected both Ti and local nitric oxide synthase (NOS) inhibitor. (Mol Cell Biochem 278: 65–69, 2005)     

Freeze-dried microarterial allografts

Rehydrated freeze-dried microarterial allografts were implanted to bridge arterial defects using New Zealand White rabbits as the experimental model. Segments of artery from the rabbit ear and thigh were harvested and preserved for a minimum of 2 weeks after freeze-drying. These allografts, approximately 1 mm in diameter and ranging from 1.5 to 2.5 cm in length, were rehydrated and then implanted in low-pressure and high-pressure arterial systems. Poor patency was noted in low-pressure systems in both allografts and autografts, tested in 12 rabbits. In the high-pressure arterial systems, allografts that were freeze-dried and reconstituted failed in a group of 10 rabbits with an 8-week patency rate of 30 percent. Gamma irradiation in an effort to reduce infection and antigenicity of grafts after freeze-drying was associated with a patency rate of 10 percent at 8 weeks in this system in another group of 10 rabbits. Postoperative cyclosporin A therapy was associated with a patency rate of 22.2 percent in the high-pressure arterial system in a 9-rabbit group. Control autografts in this system in a group of 10 rabbits showed a 100 percent patency at 8 weeks. Microarterial grafts depend on perfusion pressure of the vascular bed for long-term patency. Rehydrated freeze-dried microarterial allografts do not seem to function well in lengths of 1 to 2.5 cm when implanted in a high-pressure arterial system. Freeze-dried arterial allografts are probably not antigenic.     

Evaluation of ethylene-vinyl acetate copolymer as a non-inflammatory alternative to Freund's complete adjuvant in rabbits

Ethylene-vinyl acetate copolymer (EVAc) was evaluated as an antigen delivery device in laboratory rabbits. Bovine serum albumin (BSA) was incorporated with EVAc in a pellet, which was implanted subcutaneously. Serum antibody titers to BSA in four implanted rabbits were equal to titers in four rabbits injected twice with BSA in complete Freund's adjuvant. Three of four rabbits implanted with EVAc displayed no inflammation or systemic illness in response to the pellet. The fourth rabbit repeatedly developed a small abscess at the implantation site, but the lesions were less severe than complete Freund's adjuvant injection sites. The EVAc pellet is recommended as a non-inflammatory alternative method to Freund's adjuvants for producing serum antibody in rabbits.     

Influences of castration and testosterone on spring to summer changes in release of luteinizing-hormone-releasing hormone in rabbits.

Push-pull cannulae were implanted toward the tuberal region of the hypothalamus in ten intact New Zealand male rabbits. In the first experiment, rabbits were perfused at different times after castration: 5-10 days (n = 10), 22-31 days (n = 9) and 50-64 days (n = 8). The release, mean amplitude and mean frequency of luteinizing-hormone-releasing hormone (LHRH) signals from 37 perfusions in ten animals were analysed in intact rabbits and at different times after castration. No significant changes in release of LHRH and in amplitude were observed, but the frequency was significantly higher 22-31 days after castration than in intact rabbits (intact: 0.86 +/- 0.12; castrated: 1.20 +/- 0.13 pulses h-1, P < 0.035; n = 9). In Expt 2, testosterone and placebo Silastic capsules were implanted in the castrated rabbits. Perfusions were performed in the following four periods, defined by season and time after testosterone and placebo implants: (i) spring; before implants, (ii) late spring; 0-2 weeks after implants, (iii) summer solstice; 2-4 weeks after implants and (iv) summer; 4-6 weeks after implants. Castrated rabbits were perfused during spring; castrated rabbits with testosterone capsule implants were perfused during late spring, around summer solstice and in summer and castrated rabbits with placebo implants were perfused during periods (iii) and (iv). Castrated animals with placebo implants showed no significant changes in mean LHRH release and amplitude, although the frequency was significantly higher around the summer solstice period than in castrated rabbits perfused in the spring. In castrated rabbits with testosterone implants LHRH release was significantly higher in late spring than around the summer solstice and in the summer. In addition, the concentrations of LHRH in late spring were significantly higher than those of intact and castrated animals. In contrast, mean LHRH amplitude and frequency did not change. Mean amount of LHRH released and amplitude in castrated rabbits with testosterone implants were significantly lower around the summer solstice than in late spring or summer and compared with intact animals around summer solstice and in castrated rabbits in early spring. These data demonstrate that there were no significant changes in the mean amplitude and release of LHRH after castration from 5 and up to 64 days in rabbits with hypothalamic push-pull cannulae, in contrast to the well established dramatic effect of castration on gonadotrophin concentrations. However, there was a small, but significant, increase in the mean frequency of LHRH pulses 22-31 days after castration compared with values from intact rabbits.(ABSTRACT TRUNCATED AT 400 WORDS)     

Fate of axonally transported taurine and proteins in the developing rabbit visual system following optic nerve section

These experiments were performed to characterize the axonally transported taurine in the visual system of developing rabbits. [³⁵S]Taurine, transported axonally after intravitreal injection, disappeared from the components of the visual system more rapidly after nerve section than it did with intact nerves. The decrease was most rapid in the youngest animals, and tended to be most pronounced in the elements nearest to the section (optic nerve, optic tract).³H-labeled proteins present in the visual system changed less markedly than [³⁵S]taurine after nerve section; only in the youngest rabbits was there a marked decrease. These results suggest that a greater proportion of the intraaxonal taurine is labile in young rabbits than in mature rabbits.     

Comparative Study of Experimental Ocular Melanoma Using Two Implantation Techniques of B16-F10 Melanocytes

Objective: The aim of this work was to evaluate the behaviour of B16-F10 melanoma cell cultures implanted in the anterior chamber of the eye of New Zealand white rabbits by studying the clinical-pathological and ultrastructural characteristics of the lesions. Methods: One group (A) (consisting of 30 rabbits) was transclerally inoculated (1 mm from sclero-corneal limbus) with 4×10⁶ melanocytes and another group (B) (also 30 animals) was inoculated once per week for 3 consecutive weeks with 5×10⁶ cells (total 15×10⁶); 30 animals acted as the control group (C). All the lesions were processed for optic and electronic microscopy. Results: Tumoral growth in group A was 43% (13/30) and in group B 80% (24/30). All lesions were pigmented and none perforated the eyeball. Microscopically, they were a mixture of epithelioid and fusiform cells disposed around the blood vessels. Ultrastructurally, the presence of melanosomes in different stages of maturation and aberrant melanosomes were characteristic. Conclusion: We suggest that the transcleral inoculation of 15×10⁶ B16-F10 melanocytes into the anterior chamber of the eye of New Zealand white rabbits may be a valid and reproducible method for obtaining an experimental ocular melanoma model.     

Transgenic Rabbits Expressing Ovine PrP Are Susceptible to Scrapie

Transmissible spongiform encephalopathies (TSEs) are a group of neurodegenerative diseases affecting a wide range of mammalian species. They are caused by prions, a proteinaceous pathogen essentially composed of PrP^Sc, an abnormal isoform of the host encoded cellular prion protein PrPC. Constrained steric interactions between PrP^Sc and PrP^C are thought to provide prions with species specificity, and to control cross-species transmission into other host populations, including humans. Transgenetic expression of foreign PrP genes has been successfully and widely used to overcome the recognized resistance of mouse to foreign TSE sources. Rabbit is one of the species that exhibit a pronounced resistance to TSEs. Most attempts to infect experimentally rabbit have failed, except after inoculation with cell-free generated rabbit prions. To gain insights on the molecular determinants of the relative resistance of rabbits to prions, we generated transgenic rabbits expressing the susceptible V¹³⁶R¹⁵⁴Q¹⁷¹ allele of the ovine PRNP gene on a rabbit wild type PRNP New Zealand background and assessed their experimental susceptibility to scrapie prions. All transgenic animals developed a typical TSE 6–8 months after intracerebral inoculation, whereas wild type rabbits remained healthy more than 700 days after inoculation. Despite the endogenous presence of rabbit PrP^C, only ovine PrP^Sc was detectable in the brains of diseased animals. Collectively these data indicate that the low susceptibility of rabbits to prion infection is not enciphered within their non-PrP genetic background.     

Shifting of the brain stem physiological impedance after ovariectomy and oestradiol implantation in rabbits

Experiments were carried out on female rabbits with electrodes implanted chronically into the midbrain, dorsal hippocampus and the cerebral cortex. Physiological impedance of the brain stem, i.e. the lowest energy of trains of electric impulses stimulating the midbrain modulated through a feedback by the hippocampal theta rhythm and maintaining EEG arousal pattern, served as a measure of excitability of the brain stem reticular formation. After ovariectomy performed in 12 female rabbits, a rise in the brain stem physiological impedance was observed in relation to control measurements -- by 84.8%, on the average. In 8 ovariectomized female rabbits the physiological impedance decreased by 47.4% after subcutaneous implantation of oestradiol benzoate tablets. After removal of the implanted tablets the impedance increased by a mean value of 100.1% in all the female rabbits.     

基因转移治疗血友病B的动物试验和安全性探讨

本文报道了皮肤成纤维细胞基因治疗血友病Ｂ的新西兰大白兔试验及安全性检测。转有人凝血因子ＩＸｃＤＮＡ的兔皮肤成纤维细胞包埋于胶原基质中,然后进行不同方式的自体或同种异体移植,移植兔血浆中人ＩＸ因子蛋白有高水平的表达且持续稳定,腹腔移植有ＲＳＦ－ｐＣＭＶＩＸ转化细胞的兔血浆中人ＩＸ因子表达水平达１００ｎｇ／ｍｌ．持续５个月以上,腹腔移植有ＲＳＦ－ｐＣＭＶＩＸｌ转化细胞的兔血中人ＩＸ因子表达水平达２９５     

兔VX2肝癌模型制作改良及影像学评价

目的 对兔VX2 肝癌模型制作进行改良,以用于介入治疗学研究,同时探讨瘤灶的CT 表现及CT 在检测瘤灶中的作用.方法 将VX2瘤细胞接种于兔皮下使其成瘤并传代;新西兰兔24只,以改良嵌插法建立移植性肝癌模型,于建模后7、14、21 d分别行超声、CT及血管造影检查,用于检测兔肝VX2 瘤灶,评估瘤灶生长变化;随后处死动物,进行尸解,评估影像检查结果.结果 24只（100%） 动物以改良嵌插法建立移植性肝癌模型全部成功.瘤灶以种植后2周CT显示最清楚和典型,直径1 cm～2 cm 左右,平扫呈低密度或等密度,动脉早期明显强化,门脉期呈低密度,与周围肝组织分界较清楚.肝动脉造影显示肿瘤富血供.而种植后超过3 周的肿瘤大部分发生坏死.结论 嵌插改良法是一种值得推广的建立移植性肝癌模型的方法;在对瘤灶进行影像学评价上应尽量选择CT检查,接种后1 周左右的瘤灶较小而难以观察;2 周左右呈肝动脉源性血供丰富的约1 cm～2 cm的实体瘤,造影征像为肿瘤血管与肿瘤染色;3 周以上瘤灶大多出现明显示坏死;因此对1～2cm大小的兔VX2 肝癌瘤体,最适合行血管造影检查.     

Biocompatibility of subretinal parylene-based Ti/Pt microelectrode array in rabbit for further artificial vision studies

To evaluate the biocompatibility of subretinal implanted parylene-based Ti/Pt microelectrode arrays (MEA). Eyes were enucleated 3 months after MEAs were implanted into the subretinal space of rabbits. Morphological changes of the retinas were investigated by H&;E staining. Immunohistochemical staining for glial fibrillary acidic protein and opsin were performed to evaluate changes in Muller cells and photoreceptors in the retinas. Retina tissue around the array remained intact. Photoreceptor degeneration and glial cell activation were observed in the retina overlaying the MEA implant. However, the cells in the inner retinal layers were preserved. Photoreceptor degeneration and glial cell activation at the MEA–retina interface are expected to be a normal reaction to implantation. Material used in this experiment has good biocompatibility within the subretinal environment and is expected to be promising in the further retinal prosthesis studies.     

A periadventitial sirolimus-releasing mesh decreased intimal hyperplasia in a rabbit model

Autologous vein grafts used as aortocoronary bypasses are often prone to intimal hyperplasia, which results in stenosis and occlusion of the vein. The aim of this study was to prevent intimal hyperplasia using a newly developed perivascular system with sustained release of sirolimus. This system of controlled drug release consists of a polyester mesh coated with a copolymer of L-lactic acid and epsilon-caprolactone that releases sirolimus. The mesh is intended for wrapping around the vein graft during surgery. The mesh releasing sirolimus was implanted in periadventitial position onto arteria carotis communis of rabbits, and neointimal hyperplasia was then assessed. We found that implanted sirolimus-releasing meshes reduced intima thickness by 47+/-10 % compared to a vein graft after 3 weeks. The pure polyester mesh decreased vein intima thickness by 35+/-9 %. Thus, our periadventitial system for controlled release of sirolimus prevented the development of intimal hyperplasia in autologous vein grafts in vivo in rabbits. A perivascularly applied mesh releasing sirolimus is a promising device for preventing stenosis of autologous vein grafts.     

Bacteriocin-producing strain of Enterococcus faecium EK 13 with probiotic character and its application in the digestive tract of rabbits

Enterococcus faecium EK 13 is a bacteriocin-enterocin A producing strain with probiotic properties. In this study its colonization, stability and effect on microflora in rabbits was studied as well as its influence on zootechnical parameters. Fifty rabbits of both sexes (HYPLUS, 30-day old; after weaning) were divided into control (CG) and experimental (EG) groups. They were fed a standard diet. Moreover, 25 rabbits in EG were fed daily (for 4 weeks) 15 g (separate doses ∼1.6 g) of lyophilized EK13 strain (rifampicin resistant variant — rif^R; 10⁹ cfu/g) dissolved in drinking water. After cessation of EK13 (rif^R) strain application, the rabbits in both groups were fed a standard diet for the next 2 weeks. Sampling was performed in double on day 0 (at the beginning of experiment), weekly during EK13 (rif^R) strain application as well as on week 1 and 2 after cessation of EK13 (rif^R) strain application. The counts of EK13 (rif^R) strain reached 7.1 ± 2.6 log₁₀ cfu/g after 4 weeks and even on week 2 after its cessation the counts 5.6 ± 2.3 log₁₀ cfu/g were determined. The total counts of enterococci in the rabbits were already increased in EG comparing with CG (p < 0.05); even 2 weeks after EK13 (rif^R) strain cessation, their counts in EG were 7.2 ± 2.6 log₁₀ cfu/g (p < 0.001). Enterococci in CG reached at the same time the value 3.7 ± 2.6 log₁₀ cfu/g. The counts of E. coli were significantly reduced in EG during 4 weeks (p < 0.05, p < 0.001). Even 2 weeks after EK13 (rif^R) strain cessation significant difference in E. coli counts between CG and EG was detected (p < 0.001). Enterobacteria in EG were significantly reduced (p < 0.001). Average daily gain in EG was 41.0 ± 3.83 in comparison to CG (40.6 ± 3.72); it means almost the same; although rabbits in EG showed higher feed intake per kg of gain than rabbits in CG. Preliminary results demonstrated that EK13 is a perspective probiotic candidate for rabbits. Presented at the Second Probiotic Conference, Košice, 15–19 September 2004, Slovakia.     

Chicken erythrocyte membranes: comparison of nuclear and plasma membranes from adults and embryos

These experiments were designed to determine whether the migration of RNA molecules from an implanted nucleus to the host cytoplasm and from there into the host cell nucleus against a concentration gradient might reflect an artefact induced by the process of nuclear transplantation. That is, are RNA molecules, as previously shown for certain nuclear proteins, caused to artefactually leave a manipulated nucleus and then move into the host cell nucleus (as well as return to the grafted nucleus) during the recovery period?A variety of experiments involving different kinds of manipulative sequences and different numbers of nuclear transplantations suggest—but do not prove—that no artefact is involved in the migration of RNA from one nucleus to another but two experiments strongly support the view that the shuttling activity is a normal physiological process. One of the latter involved a determination of the rate of egress of ³H-RNA from an implanted nucleus and reveals that that rate, in contrast with the equivalent rate of egress for labeled proteins which is clearly abnormal after micromanipulation, is totally consonant with the rate of movement of RNA from nucleus to cytoplasm established from experiments that do not involve micromanipulation. The other experiment involves comparison of (1) the amount of radioactivity acquired by an unlabeled nucleus present in the cell at the time a labeled nucleus is implanted with (2) the amount of radioactivity acquired by an unlabeled nucleus implanted after a labeled nucleus had been implanted and had time to recover from any possible operation-induced trauma. With ³H-protein nuclei the host nuclei of (1) acquired much more label than the host nuclei of (2) because in (1) the host nuclei were able to acquire much of the artefactually-released ³H-protein. For the ³H-RNA experiments, however, little difference was found between (1) and (2) in the amount of label acquired by the host cell nuclei. It can be concluded that little, if any, of the non-random shuttling activity of RNA molecules can be a reflection of an artefact.     

兔脑种植VX2肿瘤动物模型的建立

目的建立兔VX2肿瘤脑内种植动物模型,观察其生长特性。方法采用兔脑内VX2肿瘤组织块种植法将VX2肿瘤组织块种植入24只成年New Zealand大白兔右侧大脑皮质内,用B超检测肿瘤的生长情况,在实验兔在肿瘤种植后第13、171、9、21、232、5天取材,进行组织学观察。并观察实验兔在种植VX2肿瘤后的生存期及出现厌食、偏瘫等神经系统体征和死亡的时间。结果VX2肿瘤组织块种植入脑内后荷瘤兔的中位生存期为24.5 d,平均生存期为24.8 d,肿瘤体积随种植后的时间在对数坐标中接近一条直线。VX2肿瘤种植入兔脑17 d后血供较丰富、呈鱼肉状生长,与正常脑组织边缘界限不清楚,第17~19天肿瘤中心出现坏死并出现腹腔内转移。光镜下从VX2肿瘤种植后第17天开始肿瘤细胞向正常脑组织浸润,并形成瘤巢,瘤周脑组织形成水肿带。结论在缺乏兔源性脑肿瘤的情况下,采用兔VX2肿瘤组织块颅内种植能较好模拟颅内肿瘤生长,为对脑肿瘤的某些实验研究提供条件。     

Evaluating the role of autologous mesenchymal stem cell seeded on decellularized pericardium in the treatment of myocardial infarction: an animal study

Inappropriate left ventricular remodeling following myocardial infarction (MI) can result in subsequent severe dysfunction. In this study, we tested the hypothesis that decellularized pericardium (DP) or seeded pericardial patch with autologous adipose-derived mesenchymal stem cells (ADMSCs) could be safely used in a MI scar and could improve heart function. Twelve rabbits were randomly divided into three equal groups. Four weeks after MI induction by ligation of the left anterior descending artery in 12 rabbits, animals of G1 (n = 4) received DP patch with labeled ADMSCs. DP patch was implanted in animals of G2 (n = 4). Rabbits of G3 (n = 4) remained without any intervention after MI induction (control group). Serial examinations including echocardiography, electrocardiography (ECG), scanning electron microscopy, histology and immunohistochemistry (IHC) were performed to evaluate the efficacy of the implanted scaffolds on recovery of the infracted myocardium. The results demonstrated that left ventricular contractile function and myocardial pathological changes were significantly improved in rabbits implanted with either DP or ADMSC-seeded pericardium. However, the seeded pericardium was more effective in scar repairing 2 months after the operation, IHC staining with Desmin and CD34 and positive immunofluorescence staining verified the differentiation of ADMSCs to functional cardiomyocytes. This approach may involve the application of autologous ADMSCs seeded on pericardial patch in an attempt to regenerate a contractible myocardium in an animal model of MI.     

Changes of intracranial pressure during head-down tilt in anesthetized and conscious rabbits

Effects of head-down tilt on intracranial pressure were studied in anesthetized and conscious rabbits. Adult Japanese white rabbits of both sexes, weighing 2.5-3.5 kg, were used in the experiments. Experiment 1. Animals were anesthetized with pentobarbital, and ICP was monitored through a catheter inserted into the subarachnoid space. ICP elevated immediately after the onset of 45 degrees HDT and gradually reduced toward the baseline level in the next 8 hours. Experiment 2. Each rabbit was exposed to 45 degrees HDT for 24 hours and the ICP was measured through a catheter which had been implanted 7 days before. In the conscious rabbits, ICP increased about 4 mmHg after the onset of 45 degrees HDT, further increased gradually to the peak at 11 hours of HDT, and then started to return to the baseline. These results suggest that the time course of the change in ICP during HDT is considerably different between anesthetized and conscious rabbits.     

Hemodynamic Changes Caused by Flow Diverters in Rabbit Aneurysm Models: Comparison of Virtual and Realistic FD Deployments Based on Micro-CT Reconstruction

Adjusting hemodynamics via flow diverter (FD) implantation is emerging as a novel method of treating cerebral aneurysms. However, most previous FD-related hemodynamic studies were based on virtual FD deployment, which may produce different hemodynamic outcomes than realistic (in vivo) FD deployment. We compared hemodynamics between virtual FD and realistic FD deployments in rabbit aneurysm models using computational fluid dynamics (CFD) simulations. FDs were implanted for aneurysms in 14 rabbits. Vascular models based on rabbit-specific angiograms were reconstructed for CFD studies. Real FD configurations were reconstructed based on micro-CT scans after sacrifice, while virtual FD configurations were constructed with SolidWorks software. Hemodynamic parameters before and after FD deployment were analyzed. According to the metal coverage (MC) of implanted FDs calculated based on micro-CT reconstruction, 14 rabbits were divided into two groups (A, MC >35%; B, MC <35%). Normalized mean wall shear stress (WSS), relative residence time (RRT), inflow velocity, and inflow volume in Group A were significantly different (P<0.05) from virtual FD deployment, but pressure was not (P>0.05). The normalized mean WSS in Group A after realistic FD implantation was significantly lower than that of Group B. All parameters in Group B exhibited no significant difference between realistic and virtual FDs. This study confirmed MC-correlated differences in hemodynamic parameters between realistic and virtual FD deployment.     

交联I型胶原复合生物玻璃在兔股骨远端缺损中的成骨作用

摘要 目的：评价交联度不同的I型胶原复合生物玻璃后作为人工骨移植物在兔股骨髁部骨缺损中的修复作用,以研究一种成骨性能优秀,降解速度令人满意,且具有可塑性,便于术中使用的新型人工骨移植材料。方法：本研究设置实验组及对照组,实验组为交联度70%的高交联I型胶原复合生物玻璃以及交联度为45%的低交联I型胶原复合生物玻璃。对照组为普通未交联I型胶原复合生物玻璃。于9只新西兰大白兔双下肢股骨髁部制备动物骨缺损模型,将随机分组后的三种骨移植物分别植入股骨髁部骨缺损模型中。术后6周取材行组织学分析研究,比较3种骨移植物在骨缺损中的新骨生成率。结果：组织学分析结果显示,高交联组的新骨生成率为5.23 0.87%,其成骨性能显著低于低交联组13.23 1.13%以及未交联组的12.63 0.92%（P<0.05）。而低交联组的新骨生成率与未交联组之间无统计学差异（P>0.05）。结论：交联度为45%的低交联I型胶原复合生物玻璃具有更好的成骨能力,作为骨移植材料在临床应用中具有更广阔的发展前景。