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Abstract The aim of this study was to evaluate safety and efficacy of a poly-L-lactic acid (PLLA)-coated magnesium (Mg)-Dysprosium (Dy) membrane in guided bone regeneration (GBR) using a rabbit calvarium model. The microstructure of the Mg-Dy membrane surface and thickness of the PLLA coating were examined. In vitro degradation and cytotoxicity test was conducted. The in vivo study used 24 white male rabbits with two 8 mm-diameter defects created on the calvaria; 12 defects were randomly assigned per group: (1) Negative control, (2) positive control, (3) uncoated Mg, and (4) PLLA-coated Mg group. Specimens were harvested at 4, 8, and 12 weeks postoperatively for radiological, histological, and histomorphometric analyses. The PLLA-coated Mg-Dy membrane showed a low degree of degradation, indicating that the coating exerted a protective effect. In the cytotoxicity test, no deformed or degenerated cells were observed. In the in vivo study, radiographic and histomorphometric analyses indicated favorable new bone formation and maintenance of the graft material for PLLA-coated Mg group. PLLA-coated Mg group, compared to the uncoated counterpart, restored the bony contour more completely, without inducing significant inflammatory response. Our results support the safety and efficacy of PLLA-coated Mg-Dy membranes for GBR both in vitro and in vivo.

OBJECTIVE To evaluate selected gastrointestinal side effects of high-concentration buprenorphine (HCB) in healthy rabbits. ANIMALS 10 healthy New Zealand White rabbits ranging in body weight between 3.0 and 3.8 kg. METHODS Eight, 6-month-old, New Zealand White rabbits received a single injection of HCB SC (0.24 mg/kg). The rabbits were previously randomized to receive SC and oral saline as a control. Two rabbits received saline for the purpose of blinding the outcome assessors. Food and water consumption, fecal and urine production, and fecal pellet number were recorded for all rabbits before HCB administration and the 3 days postinjection. RESULTS A clinically and statistically significant decrease in food and water consumption was observed in rabbits receiving an injection of HCB, compared to rabbits receiving saline. In the 24 hours after injection, HCB-treated rabbits consumed a median of 17 g of food (range, 0 to 82 g), while saline-treated rabbits consumed 122 g of food (31 to 181 g). Rabbits receiving HCB injections also produced significantly less feces both in terms of pellet numbers and overall quantity, along with decreased urine production. CLINICAL RELEVANCE A single administration of HCB has a clinically significant impact on multiple physiological functions in healthy rabbits. Administration of this drug could potentially worsen clinical signs of anorexia and decrease defecation in healthy rabbits. The effects of HCB on diseased or painful rabbits are not yet known. [ABSTRACT FROM AUTHOR]

The role of iron in promoting atherosclerosis, and hence the cardiovascular, neurodegenerative and other diseases that result from atherosclerosis, has been fiercely controversial. Many studies have been carried out on various rodent models of atherosclerosis, especially on apoE -knockout (apoE −/− ) mice, which develop atherosclerosis more readily than normal mice. These apoE −/− mouse studies generally support a role for iron in atherosclerosis development, although there are conflicting results. The purpose of the current article is to describe studies on another animal model that is not genetically manipulated; New Zealand White (NZW) rabbits fed a high-cholesterol diet. This may be a better model than the apoE −/− mice for human atherosclerosis, although it has been given much less attention. Studies on NZW rabbits support the view that iron promotes atherosclerosis, although some uncertainties remain, which need to be resolved by further experimentation. [Display omitted] [ABSTRACT FROM AUTHOR]

Bone defects are common consequences of bone trauma. The application of biomaterials as tissue scaffolds combined with oxygenating agents, as bone regeneration promoters, is an interesting strategy to improve bone repair. The present study aimed to investigate the potential of a temperature-sensitive hydrogel containing 1-bromoheptafluorooctane in repairing rabbit bone defects and its possible mechanism of action. Bone defects were surgically created in the femoral condylar of New Zealand White rabbits. The animals were divided into three groups: A) treated with the temperature-sensitive hydrogel containing 1-bromoheptafluorooctane with oxygen release; B) treated with the temperature-sensitive hydrogel containing 1-bromoheptafluorooctane without oxygen release; and C) received no treatments. At four and 12 weeks post-operation, the specimens from all groups were collected. The new bone formation was studied by morphological observation, X-ray, Micro-CT, Masson’s trichrome, and CD31 immunohistochemical staining. At 12 weeks post-operation, the bone defects were completely healed in groups A and B, while a major bone defect was still present in group C. Micro-CT showed that TMD, BVF, Tb.Th and Tb.N in group A were significantly higher compared to the other groups at each time point post-operation. The SMI value of group A showed a significant difference from the other groups at 12 weeks post-operation. The number of micro-vessels in group A was significantly higher compared to the other groups at four and 12 weeks post-operation. The oxygenating temperature-sensitive hydrogel containing 1-bromoheptafluorooctane could effectively promote new bone formation while increasing tissue vascularization, highlighting a good clinical application prospect.

Female rabbits from the age of 9 weeks till age of maturity were reared in two separate groups under long (16L: 8D) and short (control) (12L: 12D) photoperiods. The primary follicles were characterized by the presence of single layer of cuboidal granulosa cells surrounding the oocyte. Does reared under long photoperiod recorded greater primary follicle and oocyte diameter at 15 weeks of age as compared to those reared in short photoperiod. At pre-pubertal age the serum concentration of FSH was greater in long photoperiod animals as compared to those of short photoperiod animals. [ABSTRACT FROM AUTHOR]

AIM: To investigate the distribution of conjunctival lymphatic vessels in New Zealand white rabbits and its relationship with age.METHODS: Subconjunctival trypan blue was injected in four quadrants(nasal, superior, temporal, and inferior)and recorded videos. The number of lymphatic outflow pathways arising from the blebs was counted. The difference in the number of lymphatic outflow pathways across the quadrants of each group was tested by single-factor analysis of variance. Paired t-test was used to compare the differences in the number of lymphatic outflow pathways in the same rabbit quadrants across different ages.RESULTS: In New Zealand white rabbits, thick annular lymphatic vessels were mainly distributed near the limbus part of the conjunctiva. The single collecting lymphatic vessels were primarily distributed in the peripheral parts. Although the lymphatic vessels of juvenile rabbits have fewer branches, the number of lymphatic vessels in the different quadrants was no significant difference in each group(all P>0.05)and was no difference between the two age groups(all P >0.05).CONCLUSION:The lymphatic vessels were abundant in rabbit conjunctiva. The number of lymphatic vessels in each quadrant and between two age groups had no significant difference.

• Overexpression of lncRNA TCONS_02443383 upregulates PPAR signaling pathways in AS. • lncRNA TCONS_02443383 enhances genes related to cell adhesion in atherosclerosis. • RNA-seq and qRT-PCR validate lncRNA TCONS_02443383′s role in AS regulation. • Lentiviral plasmids upregulate lncRNA TCONS_02443383, impacting AS development. In this study, we performed RNA sequencing (RNA-seq) on the abdominal aorta tissue of New Zealand rabbits and investigated the potential association of lncRNA TCONS_02443383 with the development of AS through bioinformatics analysis of the sequencing data. The obtained results were further validated using quantitative real-time polymerase chain reaction (qRT-PCR). We induced an AS model in New Zealand rabbits by causing balloon injury to the abdominal aorta vascular wall and administering a high-fat diet. We then upregulated the expression level of the lncRNA TCONS_02443383 by injecting lentiviral plasmids through the ear vein. RNA sequencing (RNA-seq) was performed on the abdominal aorta tissues. We conducted Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway and Gene Ontology (GO) analyses. The overexpression of the lncRNA TCONS_02443383 led to an upregulation of peroxisome proliferator-activated receptor (PPAR) signaling pathways as well as genes related to cell adhesion. The overexpression of the lncRNA TCONS_02443383 can inhibit the occurrence and development of AS by upregulating peroxisome proliferator-activated receptor (PPAR) signaling pathways and genes related to cell adhesion. [ABSTRACT FROM AUTHOR]

Background The deliberate use of Bacillus anthracis spores is believed by the US government to be a high bioweapons threat. The first line of defense following potential exposure to B. anthracis spores would be postexposure prophylaxis with antimicrobials that have activity against B. anthracis. Additional therapies to address the effects of toxins may be needed in systemically ill individuals. Over the last 2 decades, the United States government (USG) collaborated with the private sector to develop, test, and stockpile 3 antitoxins: anthrax immunoglobulin intravenous (AIGIV), raxibacumab, and obiltoxaximab. All 3 products target protective antigen, a protein factor common to the 2 exotoxins released by B. anthracis , and hamper or block the toxins' effects and prevent or reduce pathogenesis. These antitoxins were approved for licensure by the United States Food and Drug Administration based on animal efficacy studies compared to placebo. Methods We describe USG-sponsored pre- and postlicensure studies that compared efficacy of 3 antitoxins in a New Zealand White rabbit model of inhalation anthrax; survival following a lethal aerosolized dose of B. anthracis spores was the key measure of effectiveness. To model therapeutic intervention, intravenous treatments were started following onset of antigenemia. Results In pre- and postlicensure studies, all 3 antitoxins were superior to placebo; in the postlicensure study, raxibacumab and obiltoxaximab were superior to AIGIV, but neither was superior to the other. Conclusions These data illustrate the relative therapeutic benefit of the 3 antitoxins and provide a rationale to prioritize their deployment. [ABSTRACT FROM AUTHOR]

Diarrhoeal diseases are the second leading cause of death for children under 5 years old in 69 low- and middle-income countries, with an annual economic burden of US$ 4 billion and over 525,000 lives lost. Cholera and enterotoxigenic Escherichia coli (ETEC) traveller's diarrhoea are major diarrhoeal diseases caused by Vibrio cholerae (O1 and O139 serogroups) and ETEC, which have similar pathogeneses and can co-infect. There is no exclusive vaccine for ETEC, but cholera vaccines containing the cholera toxin B (CT-B) component offer short-term cross-protection. However, licensed oral cholera vaccines are expensive due to cold-chain supplies and the need for multiple doses. A cost-effective, dual-protection, live, cold-chain-free vaccine is, therefore, required for vaccination campaigns in low-resource settings, and MyChol - a prototype cold-chain-free live attenuated cholera vaccine, targeting V. cholerae O139 and ETEC H10407 - was developed in this context. The vaccine was evaluated in three animal models (Sprague Dawley [SD] rats, BALB/c mice and New Zealand white rabbits) for safety, colonisation capacity, reactogenicity and immunogenicity against challenge strains. In suckling mice, MyChol displayed high colonisation potential compared to unformulated VCUSM14P (the vaccine candidate) and wild-type O139. In the acute toxicity assessment, the SD rats with the highest MyChol dose (1 × 10 7 colony-forming unit [CFU]/kg) demonstrated no adverse effects or mortality. Mice vaccinated with MyChol exhibited elevated antibody levels, including anti-CT, anti-heat-labile enterotoxin (LT), anti-CT-B and anti-LT-B. Anti-CT antibodies neutralised LT toxin in ETEC H10407 in challenge studies and cross-protected against ETEC H10407 in both mice and rabbits, preventing weight loss and diarrhoea. Ileal loop experiments in rabbits and BALB/c mice showed no reactogenicity. This review, based on our previous research, therefore provides valuable insights into improving the selection of animal models to advance preclinical evaluations of diarrhoeal vaccines., Competing Interests: Conflicts of Interest: None., (© Penerbit Universiti Sains Malaysia, 2024.)

Rabbit haemorrhagic disease virus (RHDV) is associated with high morbidity and mortality in the European rabbit (Oryctolagus cuniculus). In 2010, a genetically distinct RHDV named RHDV2 emerged in Europe and spread to many other regions, including North America in 2016. Prior to this study it was unknown if eastern cottontails (ECT(s); Sylvilagus floridanus), one of the most common wild lagomorphs in the United States, were susceptible to RHDV2. In this study, 10 wild‐caught ECTs and 10 New Zealand white rabbits (NZWR(s); O. cuniculus) were each inoculated orally with either RHDV (RHDVa/GI.1a; n = 5 per species) or RHDV2 (a recombinant GI.1bP‐GI.2; n = 5 per species) and monitored for the development of disease. Three of the five ECTs that were infected with RHDV2 developed disease consistent with RHD and died at 4 and 6 days post‐inoculation (DPI). The RHDV major capsid protein/antigen (VP60) was detected in the livers of three ECTs infected with RHDV2, but none was detected in the ECTs infected with RHDV. Additionally, RHD viral RNA was detected in the liver, spleen, intestine and blood of ECTs infected with RHDV2, but not in the ECTs infected with RHDV. RHD viral RNA was detected in urine, oral swabs and rectal swabs in at least two of five ECTs infected with RHDV2. One ECT inoculated with RHDV2 seroconverted and developed a high antibody titre by the end of the experimental period (21 DPI). ECTs inoculated with the classic RHDV did not seroconvert. In comparison, NZWRs inoculated with RHDV2 exhibited high mortality (five of five) at 2 DPI and four of five NZWRs inoculated with RHDV either died or were euthanized at 2 DPI indicating both of these viruses were highly pathogenic to this species. This experiment indicates that ECTs are susceptible to RHDV2 and can shed viral RNA, thereby suggesting this species could be involved in the epidemiology of this virus. [ABSTRACT FROM AUTHOR]

This study was aimed to compare the eff ect of 1% atropine, 1% cyclopentolate, 0.5% tropicamide, and 10% phenylephrine eye drops on intraocular pressure (IOP) and central corneal thickness (CCT) in New Zealand White rabbits. Adult male, eight, New Zealand White rabbits were randomly received each of four mydriatic eye drops separately on left eye at a one-week washout period. Each rabbit received all of five diff erent treatments (sterile saline solution, four mydriatic drugs) on the left eye, whereas no measurements were performed on the right eyes during the experiment. The IOP and CCT recordings of rabbits were performed until the pupil returned to normal diameter. The mean CCT values of sterile saline, 1% atropine, 0.5% tropicamide, 1% cyclopentolate, and 10% phenylephrine were 370±15, 368±17, 372±15, 364±18, and 360±17 μm, respectively, and no statistically significant diff erences (P>0.05) were observed among groups. The mean IOP values of control (sterile saline), 1% atropine, 0.5 % tropicamide, 1% cyclopentolate, and 10% phenylephrine as, 9.7±2.1, 10.4±1.8, 10.3±2.1, 11.0±2.1, and 10±1.8 mmHg, respectively, and these were not statistically significant among groups (P>0.05). In conclusion, topical 1% atropine, 0.5% tropicamide 1% cyclopentolate, and 10% phenylephrine do not have significantly eff ect on IOP and CCT in New Zealand white rabbits.

Background and Aim: Adipose tissue-derived stromal vascular fraction (SVF) contains a heterogeneous cell population comprising multipotent adipose-derived stem cells. Regenerative therapy using adipose-derived SVF has broad applications in bone tissue engineering due to the superior osteogenic potential of SVF. This study was designed to standardize and characterize adipose-derived SVF obtained from New Zealand white rabbits for bone tissue engineering and other potential applications. Materials and Methods: Ten skeletally mature and clinically healthy adult New Zealand white rabbits were used in this study. The SVF was prepared using surgically resected interscapular adipose tissue following enzymatic digestion with 0.1% collagenase type I solution. The SVF pellet obtained after the final centrifugation step was suspended in a 0.5 mL control solution to obtain ready-to-use adipose-derived SVF. The freshly prepared SVF was characterized based on the total SVF cell count and cell yield per gram of adipose tissue. The SVF cells were enumerated using a hemocytometer. Results: Interscapular adipose tissue depots are ideal for preparing autologous adipose-derived SVF due to the ease of access. The interscapular adipose-derived SVF prepared by enzymatic digestion had an average cell yield of 3.15±0.09×106 cells/g adipose tissue. Freshly prepared SVF had a total cell count of 3.15±0.09×104 cells/μL. Conclusion: The enzymatic digestion of adipose tissue using 0.1% collagenase resulted in better cell yield per gram than methods previously reported in rabbits. The use of adipose-derived SVF can preclude the requirement for an additional culture period. In addition, it may also reduce the risk of extensive cell contamination, which makes it a safe and cost-effective strategy for bone tissue engineering applications.

Background: The selection and validation of stably expressed reference genes is key for accurately quantifying the mRNA abundance of genes under different treatments. In the rabbit model of fasting caecotrophy, reports about the selection of stable reference genes are not available. Methods and results: This study aims to screen suitable reference genes in different tissues (including uterus, cecum, and liver) of rabbits between control and fasting caecotrophy groups. RT-qPCR was used to analyze the expression levels of eight commonly used reference genes (including GAPDH, 18S rRNA, B2M, CYP, HPRT1, β-actin, H2afz, Ywhaz), and RefFinder (including geNorm, NormFinder, and BestKeeper) was used to analyze the expression stability of these reference genes. Our results showed that the most stable reference genes were different in different tissues and treatments. In the control and fasting caecotrophy groups, CYP, GAPDH and HPRT1 were proven to be the top stable reference genes in the uterus, cecum, and liver tissues, respectively. GAPDH and Ywhaz were proven to be the top two stable reference genes among uterus, cecum, and liver in both control and fasting caecotrophy groups. Conclusions: Our results indicated that the combined analysis of three or more reference genes (GAPDH, HPRT1, and Ywhaz) are recommended to be used for RT-qPCR normalization in the rabbit model of fasting caecotrophy, and that GAPDH is a better choice than the other reference genes for normalizing the relative expression of target genes in different tissues of fasting caecotrophy rabbits. [ABSTRACT FROM AUTHOR]

The present study investigated the gross and histological description of the rabbit testes with the histomorphometrical indices of the testes. Four male intact New Zealand white rabbits were procured with average weight of 1.35 ±0.13kg and were housed in individual cages at the animal house of the Faculty of Veterinary Medicine, University of Ibadan. Gross pictures and measurements of the testes were recorded while the testes tissues were processed for histology and histometric assessment of seminiferous tubules. Results showed that gross measurement of the right testis were about 2.88cm in length and 0.61cm in breadth. The measurement of the left testis were about 2.65cm and 0.65cm. The average histomorphometrical readings for the seminiferous tubular diameter and seminiferous epithelial height were 265.84µm and 204.09µm respectively. The histological slides revealed normal testicular architecture in the rabbits.

A total of twenty four unsexed New Zealand White (NZW) rabbits, weaned at 5 weeks of age, were observed to assess the impacts of some environmental stressors like stocking density (SD) and external parasite infestation (mite) on the growth performance and some blood biochemical parameters of this growing rabbits and assess the use of Oregano Essential Oil (OEO) supplementation as an antistressor for the rabbit intensification and mite infestation problems. NZW rabbits were housed in wire cages (45 cm x 45 cm x35 cm) in groups of 2 rabbits cage-1 (low stocking density; LSD) and 4 rabbits cage-1 (high stocking density; HSD). For the two densities, NZW rabbits were fed three diets with variable OEO levels and experimentally infested with P. cuniculi for 7 weeks by the following manner, (T1) group was the control group that has 0.0 OEO level kg-1 diet without mite infestations, (T2) and (T3) group were supplemented with 200 mg OEO kg-1 diet but only (T3) group was experimentally infested with mites, while the last treatment (T4) was experimentally infested with mites and supplemented with 400 mg OEO kg-1 diet. Finally, the current study found that a low dose of OEO-based feed had a favorable influence on the growth performance of NZW rabbits kept at LSD, with apparent benefits on antioxidant defense and innate immunity status. Our results also revealed that feed conversion ratio in rabbits provided with phytogenic supplemented diets had significantly lower values than in rabbits fed other treatments, indicating that phytogenics can promote growth. As a result, the practical consequences of phytogenic inclusion in rabbit feeds include the potential to improve rabbit growth performance and feed utilization. This would allow for faster rabbit growth, which would result in increased production time at optimal density while avoiding rabbits' parasitic infestations with mite. In conclusion, the findings of this study revealed that adding OEO in a dose of 200 mg kg-1 diet enhanced feed utilisation, rabbit somatic growth and ameliorating intensification and mite infestation stress effects on NZW rabbits. [ABSTRACT FROM AUTHOR]

This study was aimed to compare the effect of 1% atropine, 1% cyclopentolate, 0.5% tropicamide, and 10% phenylephrine eye drops on intraocular pressure (IOP) and central corneal thickness (CCT) in New Zealand White rabbits. Adult male, eight, New Zealand White rabbits were randomly received each of four mydriatic eye drops separately on left eye at a one-week washout period. Each rabbit received all of five different treatments (sterile saline solution, four mydriatic drugs) on the left eye, whereas no measurements were performed on the right eyes during the experiment. The IOP and CCT recordings of rabbits were performed until the pupil returned to normal diameter. The mean CCT values of sterile saline, 1% atropine, 0.5% tropicamide, 1% cyclopentolate, and 10% phenylephrine were 370±15, 368±17, 372±15, 364±18, and 360±17 μm, respectively, and no statistically significant differences (P>0.05) were observed among groups. The mean IOP values of control (sterile saline), 1% atropine, 0.5% tropicamide, 1% cyclopentolate, and 10% phenylephrine as, 9.7±2.1, 10.4±1.8, 10.3±2.1, 11.0±2.1, and 10±1.8 mmHg, respectively, and these were not statistically significant among groups (P>0.05). In conclusion, topical 1% atropine, 0.5% tropicamide 1% cyclopentolate, and 10% phenylephrine do not have significantly effect on IOP and CCT in New Zealand white rabbits. [ABSTRACT FROM AUTHOR]

Background and Aim: Adipose tissue-derived stromal vascular fraction (SVF) contains a heterogeneous cell population comprising multipotent adipose-derived stem cells. Regenerative therapy using adipose-derived SVF has broad applications in bone tissue engineering due to the superior osteogenic potential of SVF. This study was designed to standardize and characterize adipose-derived SVF obtained from New Zealand white rabbits for bone tissue engineering and other potential applications. Materials and Methods: Ten skeletally mature and clinically healthy adult New Zealand white rabbits were used in this study. The SVF was prepared using surgically resected interscapular adipose tissue following enzymatic digestion with 0.1% collagenase type I solution. The SVF pellet obtained after the final centrifugation step was suspended in a 0.5 mL control solution to obtain ready-to-use adipose-derived SVF. The freshly prepared SVF was characterized based on the total SVF cell count and cell yield per gram of adipose tissue. The SVF cells were enumerated using a hemocytometer. Results: Interscapular adipose tissue depots are ideal for preparing autologous adipose-derived SVF due to the ease of access. The interscapular adipose-derived SVF prepared by enzymatic digestion had an average cell yield of 3.15±0.09×106 cells/g adipose tissue. Freshly prepared SVF had a total cell count of 3.15±0.09×104 cells/µL. Conclusion: The enzymatic digestion of adipose tissue using 0.1% collagenase resulted in better cell yield per gram than methods previously reported in rabbits. The use of adipose-derived SVF can preclude the requirement for an additional culture period. In addition, it may also reduce the risk of extensive cell contamination, which makes it a safe and costeffective strategy for bone tissue engineering applications. [ABSTRACT FROM AUTHOR]

The present study investigated the gross and histological description of the rabbit testes with the histomorphometrical indices of the testes. Four male intact New Zealand white rabbits were procured with average weight of 1.35 ±0.13kg and were housed in individual cages at the animal house of the Faculty of Veterinary Medicine, University of Ibadan. Gross pictures and measurements of the testes were recorded while the testes tissues were processed for histology and histometric assessment of seminiferous tubules. Results showed that gross measurement of the right testis were about 2.88cm in length and 0.61cm in breadth. The measurement of the left testis were about 2.65cm and 0.65cm. The average histomorphometrical readings for the seminiferous tubular diameter and seminiferous epithelial height were 265.84μm and 204.09μm respectively. The histological slides revealed normal testicular architecture in the rabbits. [ABSTRACT FROM AUTHOR]

Background: The aim of the study was to estimate the volume values of the cranial cavity and nasal cavity structures and to compare the efficiency of manual segmentation of three-dimensional reconstruction and Cavalieri's principle (CP) methodologies.Materials and Methods: Volume values of the cranial cavity, maxillary sinus (MS), dorsal conchal sinus (DCS), dorsal nasal meatus (DNM), middle nasal meatus (MNM), ventral nasal meatus (VNM), ventral nasal concha (VNC), middle nasal concha (MNC) and nasal vestibule (NV) were estimated with manual segmentation and CP from micro-computed tomography images in 5 male New Zealand white rabbits. Volume measurements and elapsed time were compared with each other. Three-dimensional reconstruction models of nasal and cranial cavity structures were created.Results: There was a statistically significant difference between methods of the MS, DCS, DNM, MNM, VNM, VNC, and MNC volume measurements. Additionally, there was a statistically significant difference between the volumetric analysis time period of the methods and CP was found much shorter than manual segmentation.Conclusions: Realistic results were achieved in a short time with the CP among the stereology methods. It is thought that these image and quantitative data results can be used for modelling, toxicology and pathology studies such as acute and chronić rhinitis or rhino sinusitis as well as a good understanding of the relationship of the anatomical structures in the nasal cavity. [ABSTRACT FROM AUTHOR]

Cecotrophy is a special behaviour of rabbits. Eating soft faeces can improve feed efficiency and maintain gut flora in rabbits. In our previous study, we found that fasting from soft faeces significantly reduced growth rate and total cholesterol (TC) in New Zealand white rabbits (NZW rabbits), thereby resulting in lower values for body weight and fat deposition in the soft faeces fasting group than in the control group. However, it has not been demonstrated whether cecotrophy by NZW rabbits can regulate lipid metabolism by changing the diversity of caecal microorganisms. In this study, thirty‐six 28‐day‐old weaned NZW female rabbits were randomly divided into two groups (the soft faeces fasting group and the control group) and fed to 90 days. Rabbits in the experimental group were treated with an Elizabeth circle to prevent them from eating their soft faeces. Then, the caecal contents of three rabbits from the soft faeces fasting group and three rabbits from the control group were collected for metagenomic sequencing. We found that the abundance of Bacteroides increased, while Ruminococcus decreased, compared with the control group after fasting from soft faeces. Relative abundance was depressed for genes related to metabolic pathways such as ascorbate and aldarate metabolism, riboflavin metabolism and bile secretion. Moreover, there was a general correlation between variation in microbial diversity and fat deposition. Bacteroides affects body weight and TC by participating in the riboflavin metabolism pathway. By investigating the effect of cecotrophy on caecal microorganisms of rabbits, we identified the key microorganisms that regulate the rapid growth performance of NZW rabbits, which may provide useful reference for the future research and development of microecological preparations for NZW rabbits. [ABSTRACT FROM AUTHOR]

Introduction and hypothesis: New Zealand white rabbits are an inexpensive large-animal model. This study explored the rabbit as a model for mesh-augmented colpopexy using the intra-abdominal vagina. We hypothesized that polypropylene mesh would negatively impact rabbit vaginal smooth muscle (VSM) morphology and contractile function, similar to the nonhuman primate (NHP)—the established model for prolapse mesh evaluation. Methods: Restorelle was implanted onto the vagina of ten rabbits via lumbar colpopexy after a hysterectomy. Ten rabbits served as sham. Twelve weeks post-implantation, the vagina was excised and VSM morphology and vaginal contractility were assessed. Outcome measures were compared using independent samples t and Mann-Whitney U tests with a Bonferroni correction, where appropriate. Results from the rabbits were compared with published NHP data. Results: Animals had similar age, parity and BMI. VSM was 18% thinner after Restorelle implantation, P = 0.027. Vaginal contractility was 43% decreased in response to 120 mM KCl (P = 0.003), similar to the 46% reduction observed in the NHP vagina implanted with Restorelle (P = 0.027). Three meshes wrinkled in vivo, resulting in dramatic thinning of the underlying vagina in the area of the mesh causing a mesh exposure. Conclusions: Polypropylene mesh negatively impacts VSM morphology and vaginal contractility in the rabbit, similar to the NHP, suggesting that the rabbit may serve as an alternative large-animal model. The vaginal thinning and appearance of a mesh exposure in the area of a mesh wrinkle suggest the rabbit may also serve as a model for understanding the pathophysiology of mesh exposure. [ABSTRACT FROM AUTHOR]

There are several animal models routinely used for study of the spinal fusion process and animal selection largely depends on the scientific question to be answered. This review outlines the advantages and disadvantages of various animal models used to study spinal fusion and describes the New Zealand White (NSW) rabbit which is the most popular preclinical model to study spinal fusion. We outline critical steps required in planning and performing spinal fusion surgery in this model. This includes determination of the required animal number to obtain statistical significance, an outline of appropriate technique for posterolateral fusion and other components of completing a study. As advances in drug delivery move forward and our understanding of the cascade of gene expression occurring during the fusion process grows, performing and interpreting preclinical animal models will be vital to validating new therapies to enhance spinal fusion.

Species-dependent differences in relative incidence of spontaneous variations and malformations should be considered in the assessment of the translational value of reproductive and developmental safety assessments. The objective of this evaluation was to compare litter parameters and the frequency of external, visceral, and skeletal malformations and variations across species in the Sprague-Dawley rat, New Zealand White rabbit, and Göttingen minipig and to determine whether notable differences exist. Pregnant female rats (n = 824), rabbits (n = 540), and minipigs (n = 70) from vehicle control groups were included in the analysis, equating to 10,749 rat, 5,073 rabbit, and 378 pig fetuses collected at term by cesarean delivery. Preimplantation loss was more frequent than postimplantation loss in the rat and rabbit, whereas the opposite was observed in the minipig. Several external and visceral malformations and variations such as domed head, bent tail, abdominal edema, and anal atresia were observed in all 3 species. Visceral malformations of the heart and major blood vessels were remarkably more frequent in the minipig and rabbit, respectively; ventricular and atrium septum defects were observed in 1.9% and 2.1%, respectively, for the minipig fetuses, whereas they were observed in equal or less than 0.02% among the rat and rabbit fetuses evaluated in this study. Understanding species-dependent differences in spontaneous variations and malformations can be useful for the interpretation of embryo–fetal development study results. The current analysis identified relevant differences between commonly used species in reproductive toxicology with potential implications for data assessment. [ABSTRACT FROM AUTHOR]

Background: Gastrointestinal (GI) endocrine cells produce many GI hormones that perform various physiological functions of the digestive system. Aims: We aimed to investigate the presence and distribution of immunoreactive (IR) endocrine cells to glucagon, somatostatin, cholecystokinin-8 (CCK-8), serotonin, secretin and histamine in the stomach of adult male New Zealand White rabbit (Oryctolagus cuniculus). Methods: For immunohistochemical staining, peroxidase anti-peroxidase (PAP) method was applied to stomach samples. Results: Glucagon-IR cells of closed- and open type were found throughout all the stomach parts examined. Somatostatin-IR cells of closed- and open type in the cardiac and oxyntic glands were localized to deep portions of foveola gastrica. CCK-8 IR cells that were not observed in the cardia and fundus were mostly localized to the glands and lamina epithelialis in the pyloric part near the duodenum. Oval-shaped open and closed type serotonin-IR cells were mostly dispersed throughout the fundic and pyloric glands. Secretin-IR cells were rare in the pyloric and cardiac region although they were not observed in the fundic glands. Histamine-IR cells were rarely found in the cardia, fundus and pylorus. Conclusion: Our findings show that glucagon, histamine, somatostatin, secretin and serotonin might be produced by all the stomach regions while pyloric region had only CCK-8 IR. These distribution patterns also provide further evidence of species-specific differences, which might be important from the evolutionary aspect of the digestive tract in relation to evolutional niches and nutrient resources. [ABSTRACT FROM AUTHOR]

Bone defects are common consequences of bone trauma. The application of biomaterials as tissue scaffolds combined with oxygenating agents, as bone regeneration promoters, is an interesting strategy to improve bone repair. The present study aimed to investigate the potential of a temperature-sensitive hydrogel containing 1-bromoheptafluorooctane in repairing rabbit bone defects and its possible mechanism of action. Bone defects were surgically created in the femoral condylar of New Zealand White rabbits. The animals were divided into three groups: A) treated with the temperature-sensitive hydrogel containing 1-bromoheptafluorooctane with oxygen release; B) treated with the temperature-sensitive hydrogel containing 1-bromoheptafluorooctane without oxygen release; and C) received no treatments. At four and 12 weeks post-operation, the specimens from all groups were collected. The new bone formation was studied by morphological observation, X-ray, Micro-CT, Masson's trichrome, and CD31 immunohistochemical staining. At 12 weeks post-operation, the bone defects were completely healed in groups A and B, while a major bone defect was still present in group C. Micro-CT showed that TMD, BVF, Tb.Th and Tb.N in group A were significantly higher compared to the other groups at each time point post-operation. The SMI value of group A showed a significant difference from the other groups at 12 weeks post-operation. The number of micro-vessels in group A was significantly higher compared to the other groups at four and 12 weeks post-operation. The oxygenating temperature-sensitive hydrogel containing 1-bromoheptafluorooctane could effectively promote new bone formation while increasing tissue vascularization, highlighting a good clinical application prospect. [ABSTRACT FROM AUTHOR]

Background: Frequency of urethral stenosis makes it necessary to develop new innovative methods of treating this disease. This pathology most often occurs in men and manifests itself in painful urination, reduced urine flow, or total urinary retention. This is a condition that requires immediate medical intervention. Methods: Experimental tests were carried out on a rabbit in order to determine the changes of pressure in the urethra system and to estimate the velocity of urine flow. For this purpose, a measuring system was proposed to measure the pressure of a fluid-filled urethra. A fluoroscope was used to observe the deformability of the bladder and urethra canal. Results: Based on these tests, the range of changes in the urethra tube diameter, the pressures inside the system, and the flow velocity during micturition were determined. Conclusions: The presented studies allowed determining the behavior of the urethra under the conditions of urinary filling. The fluid-filled bladder and urethra increased their dimensions significantly. Such large changes require that the stents used for the treatment of urethral stenosis should not have a fixed diameter but should adapt to changing urethral dimensions.

Introduction: Critical size defects (CSD) in the long bones of New Zealand White rabbits (Oryctolagus cuniculus) have been used for years as an experimental model for investigation of the effectiveness of a new bone substitute material. There are varieties of protocols available in the literature. This technical note attempts to present an alternative surgical technique of a CSD in the New Zealand white rabbit tibia. Methods: Thirty-nine New Zealand White rabbits were used in this study. A CSD of approximately 4.5 mm (width) X 9.0 mm (length) was surgically drilled at the proximal tibial metaphysis, approximately 1 cm from the knee joint. The surrounding of soft tissue was repositioned and sutured layer by layer with bioabsorbable surgical suture. Two x-rays of anteroposterior and lateral were taken before assessed under computed tomography scan at 6, 12 and 24 weeks. Results: This alternative method created CSD with less bleeding from the muscle observed. No mortality or other surgical complications observed within 6 weeks, 12 weeks and 24 weeks following surgery. Conclusion: A simple and safe method for performing CSD was demonstrated and recommended as an alternative approach for surgery on New Zealand White rabbits. [ABSTRACT FROM AUTHOR]

There are several animal models routinely used for study of the spinal fusion process and animal selection largely depends on the scientific question to be answered. This review outlines the advantages and disadvantages of various animal models used to study spinal fusion and describes the New Zealand White (NSW) rabbit which is the most popular preclinical model to study spinal fusion. We outline critical steps required in planning and performing spinal fusion surgery in this model. This includes determination of the required animal number to obtain statistical significance, an outline of appropriate technique for posterolateral fusion and other components of completing a study. As advances in drug delivery move forward and our understanding of the cascade of gene expression occurring during the fusion process grows, performing and interpreting preclinical animal models will be vital to validating new therapies to enhance spinal fusion. [ABSTRACT FROM AUTHOR]

Female rabbits from the age of 9 weeks till age of maturity were reared in two separate groups under long (16L: 8D) and short (12L: 12D) photoperiods. Does reared under long photoperiod showed increased body weight and ovary weight body weight ratio as compared to does reared under short photoperiod. At 15 weeks of age Graafian follicles appeared for the first time in long photoperiod group while the same appeared in the short photoperiod group at 19 weeks of age. At prepubertal and pubertal age the serum concentration of FSH and LH were more in long photoperiod animals as compared to those of short photoperiod animals. [ABSTRACT FROM AUTHOR]

Female rabbits from the age of 9 weeks till age of maturity were reared in two separate groups under long (16L: 8D) and short (control) (12L: 12D) photoperiods. Primordial follicles were present in the ovaries in all age groups. Does reared under long photoperiod recorded greater primordial follicle diameter at 15 weeks of age as compared to those reared in short photoperiod. At pre-pubertal and pubertal age the serum concentration of FSH was greater in long photoperiod animals as compared to those of short photoperiod animals. [ABSTRACT FROM AUTHOR]

Five cases (male-2, female-3) of ectopic splenic tissue in the pancreas of New Zealand White rabbits were recorded out of 144 rabbits aged between 16-25 weeks. The histomorphology of the ectopic splenic tissue compared well with normal spleen. The pancreatic parenchyma bearing ectopic splenic tissue did not exhibit any change or abnormality of pathological significance except less number of islets of Langerhans in comparison to other areas. The present cases were considered to be rare incidental finding and congenital in origin. [Vet World 2013; 6(6.000): 360-362]

Social housing of laboratory rabbits is encouraged and thought to improve animal welfare due to the social nature of this species. However, there is limited published information comparing the physiologic and cardiovascular (CV) effects of paired and single housed adult female rabbits in commonly used laboratory caging. This study describes measurement of heart rate, systolic blood pressure, activity level, body temperature and pairing methods in four female New Zealand White rabbits that were previously implanted with M10 cardiovascular telemetry devices. Data was collected in single housed rabbits having no history of social housing while they were undisturbed in the home cage, during restraint, intramuscular injections and intravenous blood collection. The same animals were then placed in compatible pairs and housed in conventional Allentown caging. As expected, we found increased activity in paired rabbits but no significant differences in body temperatures, and CV parameters in single and paired rabbits undergoing the same procedures. These data suggest that paired rabbits can be used for safety pharmacology studies with minimal impact to data, while supporting improved animal welfare. [ABSTRACT FROM AUTHOR]

Progressive tissue remodeling after myocardial infarction (MI) promotes cardiac arrhythmias. This process is well studied in young animals, but little is known about pro-arrhythmic changes in aged animals. Senescent cells accumulate with age and accelerate age-associated diseases. Senescent cells interfere with cardiac function and outcome post-MI with age, but studies have not been performed in larger animals, and the mechanisms are unknown. Specifically, age-associated changes in timecourse of senescence and related changes in inflammation and fibrosis are not well understood. Additionally, the cellular and systemic role of senescence and its inflammatory milieu in influencing arrhythmogenesis with age is not clear, particularly in large animal models with cardiac electrophysiology more similar to humans than previously studied animal models. Here, we investigated the role of senescence in regulating inflammation, fibrosis, and arrhythmogenesis in young and aged infarcted rabbits. Aged rabbits exhibited increased peri-procedural mortality and arrhythmogenic electrophysiological remodeling at the infarct border zone (IBZ) compared to young rabbits. Studies of the aged infarct zone revealed persistent myofibroblast senescence and increased inflammatory signaling over a 12-week timecourse. Senescent IBZ myofibroblasts in aged rabbits appear to be coupled to myocytes, and our computational modeling showed that senescent myofibroblast-cardiomyocyte coupling prolongs action potential duration (APD) and facilitates conduction block permissive of arrhythmias. Aged infarcted human ventricles show levels of senescence consistent with aged rabbits, and senescent myofibroblasts also couple to IBZ myocytes. Our findings suggest that therapeutic interventions targeting senescent cells may mitigate arrhythmias post-MI with age., Competing Interests: BB, KM, ES, EM, YC, NT, YL, LS, TK, AK, PB, ZQ, PC, PD, DT, Fd, BC, JS, GK No competing interests declared, (© 2023, Baggett, Murphy, Sengun et al.)

Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived respectively from computed tomography (CT) and µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation–exhalation breathing conditions using average species-specific minute volumes. Two different exposure scenarios were modeled in the rabbit based upon experimental inhalation studies. For comparison, human simulations were conducted at the highest exposure concentration used during the rabbit experimental exposures. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Due to the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the nasal sinus compared to the human at the same air concentration of anthrax spores. In contrast, higher spore deposition was predicted in the lower conducting airways of the human compared to the rabbit lung due to differences in airway branching pattern. This information can be used to refine published and ongoing biokinetic models of inhalation anthrax spore exposures, which currently estimate deposited spore concentrations based solely upon exposure concentrations and inhaled doses that do not factor in species-specific anatomy and physiology for deposition. [ABSTRACT FROM AUTHOR]

The New Zealand White rabbit has been widely used as a model of limbal stem cell deficiency (LSCD). Current techniques for experimental induction of LSCD utilize caustic chemicals, or organic solvents applied in conjunction with a surgical limbectomy. While generally successful in depleting epithelial progenitors, the depth and severity of injury is difficult to control using chemical-based methods. Moreover, the anterior chamber can be easily perforated while surgically excising the corneal limbus. In the interest of creating a safer and more defined LSCD model, we have therefore evaluated a mechanical debridement technique based upon use of the AlgerBrush II rotating burr. An initial comparison of debridement techniques was conducted in situ using 24 eyes in freshly acquired New Zealand White rabbit cadavers. Techniques for comparison (4 eyes each) included: (1) non-wounded control, (2) surgical limbectomy followed by treatment with 100% (v/v) n -heptanol to remove the corneal epithelium (1–2 min), (3) treatment of both limbus and cornea with n -heptanol alone, (4) treatment of both limbus and cornea with 20% (v/v) ethanol (2–3 min), (5) a 2.5-mm rounded burr applied to both the limbus and cornea, and (6) a 1-mm pointed burr applied to the limbus, followed by the 2.5-mm rounded burr applied to the cornea. All corneas were excised and processed for histology immediately following debridement. A panel of four assessors subsequently scored the degree of epithelial debridement within the cornea and limbus using masked slides. The 2.5-mm burr most consistently removed the corneal and limbal epithelia. Islands of limbal epithelial cells were occasionally retained following surgical limbectomy/heptanol treatment, or use of the 1-mm burr. Limbal epithelial cells were consistently retained following treatment with either ethanol or n -heptanol alone, with ethanol being the least effective treatment overall. The 2.5-mm burr method was subsequently evaluated in the right eye of 3 live rabbits by weekly clinical assessments (photography and slit lamp examination) for up to 5 weeks, followed by histological analyses (hematoxylin & eosin stain, periodic acid-Schiff stain and immunohistochemistry for keratin 3 and 13). All 3 eyes that had been completely debrided using the 2.5-mm burr displayed symptoms of ocular surface failure as defined by retention of a prominent epithelial defect (∼40% of corneal surface at 5 weeks), corneal neovascularization (2–3 quadrants), reduced corneal transparency and conjunctivalization of the corneal surface (demonstrated by the presence of goblet cells and/or staining for keratin 13). In conclusion, our findings indicate that the AlgerBrush II rotating burr is an effective method for the establishment of ocular surface failure in New Zealand White rabbits. In particular, we recommend use of the 2.5-mm rotating burr for improved efficiency of epithelial debridement and safety compared to surgical limbectomy. [ABSTRACT FROM AUTHOR]

Although effective drugs that lower intraocular pressure (IOP) in the management of glaucoma exist, their efficacy is limited by poor patient adherence to the prescribed eye drop regimen. To replace the need for eye drops, in this study we tested the hypothesis that IOP can be reduced for one month after a single targeted injection using a microneedle for administration of a glaucoma medication (i.e., brimonidine) formulated for sustained release in the supraciliary space of the eye adjacent to the drug's site of action at the ciliary body. To test this hypothesis, brimonidine-loaded microspheres were formulated using poly(lactic acid) (PLA) to release brimonidine at a constant rate for 35 days and microneedles were designed to penetrate through the sclera, without penetrating into the choroid/retina, in order to target injection into the supraciliary space. A single administration of these microspheres using a hollow microneedle was performed in the eye of New Zealand White rabbits and was found to reduce IOP initially by 6 mm Hg and then by progressively smaller amounts for more than one month. All administrations were well tolerated without significant adverse events, although histological examination showed a foreign-body reaction to the microspheres. This study demonstrates, for the first time, that the highly-targeted delivery of brimonidine-loaded microspheres into the supraciliary space using a microneedle is able to reduce IOP for one month as an alternative to daily eye drops. [ABSTRACT FROM AUTHOR]

Microneedle injection into the suprachoroidal space (SCS) enables targeted drug delivery for treatment of posterior segment diseases. This study sought to identify and characterize anatomical barriers to circumferential spread of particles in the SCS of rabbit and human cadaver eyes. These barriers could make targeting specific regions within the SCS challenging. A hollow microneedle (33-gauge, 750 μm long) was used to inject fluorescent particles into albino New Zealand White rabbit eyes ex vivo at six different positions around the limbus and a limited number of conditions in vivo . SCS injections were also performed in human cadaver eyes 8 mm and 2 mm from the optic nerve (ON). Eyes were dissected and particle distribution was quantified. In rabbit eyes, injections made in the superior or inferior hemispheres (even when injected temporally immediately adjacent to the long posterior ciliary artery (LPCA)) did not significantly cross into the other hemisphere, apparently due to a barrier formed by the LPCA. The vortex veins had a minor effect on particle deposition, limited to only around the vortex vein root. In human eyes, the short posterior ciliary arteries (SPCAs) prevented circumferential spread towards the macula and ON. In conclusion, the rabbit LPCA and the human SPCA were anatomical barriers to particle spread within the SCS. Therefore, design of drug delivery protocols targeting the SCS need to account for barriers formed by anatomical structures in order for injected drug to reach target tissues. [ABSTRACT FROM AUTHOR]

This study was aimed out to evaluate the effects of vitamin C premedication on xylazine-ketamine anesthesia in New Zealand white rabbits. Twelve New Zealand white rabbits were divided into two groups (Group XK and Group VCXK) that each had 3 males and 3 females. The animals in group XK were treated with 10 mg/kg Xylazine HCl and 50 mg/kg Ketamine HCl. The animals in group VCXK were pre-treated with 60 mg/kg Vitamin C prior to xylazine-ketamine combination. The onset of anesthesia, the length of surgical anesthesia and the recovery time were recorded. Body temperature, heart and respiratory rates were recorded at 0, 5, 10, 15, 30, 45, 60 min. In XK group onset of action and length of surgical anesthesia were 5.81±0.19 min and 55.00±2.81 min, respectively. Premedication of rabbits with 60 mg/kg vitamin C resulted in significant decrease in the onset of action (3.93±0.13 min) and increase in the duration of xylazine-ketamine anesthesia (77.50±6.15 min). The body temperature change between treatment groups were significant at 30, 45 and 60 min. This study shows that vitamin C administration prior to xylazine-ketamine anesthesia in New Zealand white rabbits decreases the time for onset of action and prolonged the length of surgical anesthesia. [ABSTRACT FROM AUTHOR]