Regional acceleratory phenomenon after orthodontic force exertion in ovariectomized rats

The application of orthodontic forces may be one of the factors that produce a regional acceleratory phenomenon (RAP) in mandibular and maxillary bones. The effect of exerted forces on bone tissue ahead of their point of application has not been extensively studied. Moreover, limited information exists regarding this phenomenon on osteoporotic bone. The study aim was to examine the role of orthodontic forces on the expression of RAP in normal and osteoporotic mature rats. Thirty-six eight-month-old skeletally mature female Wistar rats, half of which had been previously ovariectomized (OVX) at the age of 6 months, were subjected to orthodontic movement of the upper right first molar. An orthodontic force of 60 gr* was generated through a closed coil spring for 14 days. The maxillae were then removed and the area ahead of the first molar was examined histologically. On the side of orthodontic force application, distortion of bone structure and woven bone formation were observed in non-OVX rats, whereas in the OVX rats, extensive remodeling was apparent. In conclusion, the application of orthodontic forces on both normal and osteoporotic mature rats in the present study created a RAP ahead of the loaded teeth demonstrated histologically, indicating increased bone resorption and formation in the OVX rats. © 2018 A.I. Tsolakis, L. Khaldi, I. Bitsanis, I.A. Dontas

Pathophysiological changes during ischemia-reperfusion injury in rodent hepatic steatosis

Background/Aim: Ischemia and reperfusion injuries may produce deleterious effects on hepatic tissue after liver surgery and transplantation. The impact of ischemia-reperfusion injury (ΙRΙ) on the liver depends on its substrate, the percentage of liver ischemic tissue subjected to IRI and the ischemia time. The consequences of IRI are more evident in pathologic liver substrates, such as steatotic livers. This review is the result of an extended bibliographic PubMed search focused on the last 20 years. It highlights basic differences encountered during IRI in lean and steatotic livers based on studies using rodent experimental models. Conclusion: The main difference in cell death between lean and steatotic livers is the prevalence of apoptosis in the former and necrosis in the latter. There are also major changes in the effect of intracellular mediators, such as TNFα and IL-1β. Further experimental studies are needed in order to increase current knowledge of IRI effects and relevant mechanisms in both lean and steatotic livers, so that new preventive and therapeutic strategies maybe developed. © 2020 International Institute of Anticancer Research. All rights reserved

Effect of ovariectomy and Sideritis euboea extract administration on large artery mechanics, morphology, and structure in middle-aged rats

BACKGROUND: Arterial function is regulated by estrogen, but no consistent pattern of arterial mechanical remodeling in response to depleted estrogen levels is available. OBJECTIVE: To examine long-term effects of ovariectomy (OVX) on the mechanical properties, morphology, and histological structure of the carotid artery in middle-aged rats and a potentially protective effect of Sideritis euboea extract (SID), commonly consumed as "mountain tea". METHODS: 10-month-old female Wistar rats were allocated into control (sham-operated), OVX, OVX + SID, and OVX + MALT (maltodextrin; excipient used for dilution of SID) groups. They were sacrificed after 6 months and their carotid arteries were submitted to inflation/extension tests and to dimensional and histological evaluation. RESULTS: Remodeling in OVX rats was characterized by a decreased in situ axial extension ratio, along with increased opening angle, thickness, and area of the vessel wall and of its medial layer, but unchanged lumen diameter. Compositional changes involved increased elastin/collagen densities. Characterization by the "four-fiber" microstructure-motivated model revealed similar in situ biaxial response of carotid arteries in OVX and control rats. CONCLUSIONS: Carotid artery remodeling in OVX rats was largely consistent with hypertensive remodeling, despite the minor arterial pressure changes found, and was not altered by administration of SID, despite previous evidence of its osteo-protective effect. © 2017 IOS Press and the authors

The biomechanical capacity of the periosteum in intact long bones

Introduction: The biological function of the periosteum is profusely described but its contribution to the biomechanical properties of the bone has been considered negligible. The purpose of this study was to examine the biomechanical properties of periosteum-preserved long bones. Materials and methods: The biomechanical properties of both femora and tibiae of 30 male, 4-month-old Wistar rats were evaluated using a destructive three-point-bending testing protocol. In both bones from one side the periosteum was preserved, while in the contralateral bones the periosteum was stripped off. Ultimate strength, stiffness, energy absorption and deflection were derived automatically from the load-deformation curve recorded for each bone. Results: As regards the femur, the periosteum-covered bones displayed statistically significant higher values for all parameters measured compared to the periosteum-stripped bones. Ultimate strength, stiffness, absorbed energy and deflection of stripped and periosteum-covered femora were, respectively, 146.76 ± 44.71 and 196.01 ± 41.47 N, 44.25 ± 17.35 and 61.62 ± 15.07 N/mm, 0.00054 ± 0.00274 and 0.00011 ± 0.00354 Nmm, 0.67 ± 0.25 and 1.07 ± 0.28 mm. In the tibia, only energy absorption (0.00353 ± 0.00199 and 0.0010 ± 0.00339 Nmm) and deflection (1.71 ± 0.56 and 0.86 ± 0.36 mm) were significantly higher in the periosteum-covered bones. The pattern of bone failure was also different in the two groups. In periosteum-covered bones the two bone parts remained in close apposition stabilized by the periosteal membrane, while in a few cases the periosteum was stretched or torn opposite the loading site. Conclusion: The periosteum not only has significant biological function but also provides mechanical support to the bone and amplifies the biomechanical capacity of intact rat long bones in bending, probably taking advantage of its fibrous and elastic properties. © Springer-Verlag 2007

Changes of blood biochemistry in the rabbit animal model in atherosclerosis research; A time- or stress-effect

Background: Rabbits are widely used in biomedical research and especially as animal models in atherosclerosis studies. Blood biochemistry is used to monitor progression of disease, before final evaluation including pathology of arteries and organs. The aim of the present study was to assess the consistency of the biochemical profile of New Zealand White rabbits on standard diet from 3 to 6 months of age, during which they are often used experimentally. Methods and results. Eight conventional male 3-month-old New Zealand White rabbits were used. Blood samples were taken at baseline, 1, 2 and 3 months later. Plasma glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triacylglycerol concentrations, and alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, gamma glutamyl transferase activities and malondialdehyde were measured. Statistically significant time-related changes were observed in glucose, total cholesterol and triacylglycerol, which were not correlated with aortic lesions at 6 months of age. Similarly, hepatic enzyme activity had significant time-related changes, without a corresponding liver pathology. Conclusions: Age progression and stress due to single housing may be the underlying reasons for these biochemistry changes. These early changes, indicative of metabolic alterations, should be taken into account even in short-term lipid/atherosclerosis studies, where age and standard diet are not expected to have an effect on the control group of a study. © 2011 Dontas et al; licensee BioMed Central Ltd

Effect of Calcium and Vitamin D Supplementation With and Without Collagen Peptides on Volumetric and Areal Bone Mineral Density, Bone Geometry and Bone Turnover in Postmenopausal Women With Osteopenia

Collagen peptides (CPs) have been shown to potentially have a role as a treatment option in osteopenia. In the present randomized prospective study, we examined the effect of calcium, vitamin D with and without CPs supplementation on changes in volumetric bone mineral density (vBMD) and bone geometry assessed by peripheral quantitative computed tomography at the tibia, areal bone mineral density (aBMD) assessed by dual-energy X-ray absorptiometry at the lumbar spine and the hip and bone turnover markers over 12-mo. Fifty-one postmenopausal women with osteopenia were allocated to Group A who received orally 5 g CPs, 500 mg calcium and 400 IU vitamin D3 and Group B who received the same dose of calcium and vitamin D3 per day. The primary endpoint was the change of trabecular bone mineral content (BMC) and vBMD after 12-mo supplementation in Groups A and B. At the trabecular site (4% of the tibia length), Group A had a significant increase of total BMC by 1.96 ± 2.41% and cross-sectional area by 2.58 ± 3.91%, trabecular BMC by 5.24 ± 6.48%, cross-sectional area by 2.58 ± 3.91% and vBMD by 2.54 ± 3.43% and a higher % change of these parameters at 12 mo in comparison to Group B (p < 0.01, p = 0.04, p < 0.01, p = 0.04, p = 0.02, respectively). At the cortical site (38% of the tibia length), total and cortical vBMD increased by 1.01 ± 2.57% and 0.67 ± 1.71%. Furthermore, the mean aBMD at the spine was higher (p = 0.01), while bone markers decreased in Group A compared to Group B. The present study shows improvement of trabecular and cortical parameters as assessed by peripheral quantitative computed tomography at the tibia, prevention of aBMD decline and decrease of bone turnover after 12-mo supplementation with calcium, vitamin D with CPs. © 2021 The International Society for Clinical Densitometr

Mechanical behavior of colonic anastomosis in experimental settings as a measure of wound repair and tissue integrity

Aim: To determine the mechanical properties of anastomotic colonic tissue in experimental settings and therefore give a measure of wound healing. Methods: Thirty-six male Wistar rats were used as experimental models of anastomotic tissue integrity. On the 5th post-operative day, the tensile strength was measured by application of an axial force, providing a quantitative measure of anastornotic dehiscence and leakage. Results: Diagrams of the load as a function of the time [P = P (t)] and of the displacement also as a function of time [Δs = Δs (t)] were recorded for each test, permitting the design of the load versus the displacement diagram and thus providing significant data about the critical values of anastornotic failure. Quantitative data were obtained concerning the anastornotic strength of both control specimens (healthy rats), as well as specimens from non-healthy rats for comparison. Conclusion: This experimental model provides an excellent method of measuring anastomotic strength. Despite the relative small number of specimens used, this method provides an accurate way of measuring wound repair. More experimental measurements need to be performed to correlate emerging tensile strength values to anastomotic failure. © 2006 The WJG Press. All rights reserved

Per os colchicine administration in cholesterol fed rabbits: Triglycerides lowering effects without affecting atherosclerosis progress

Background: Atherosclerosis is a chronic inflammatory disease that is promoted, among others, by pro-inflammatory cytokines such as IL-1β and IL-18 produced by NLRP 3 inflammasome. Development of atherosclerotic lesions is also affected by leptin. Furthermore, inflammasome's action is interfered with other inflammatory diseases, like diabetes. On the other hand, colchicine is reported to act as anti-inflammatory agent inhibiting inflammasome's action and stabilizing atherosclerotic lesions. The purpose of this study is to investigate the effect of per os colchicine on the de novo formation of atherosclerotic lesions and on the levels of IL-18, leptin and insulin in cholesterol-fed rabbits. Methods: Twenty-three male, 2 months old New Zealand White rabbits, were seperated in 3 groups and were fed with different types of diet for 7 weeks: standard, cholesterol 1% w/w and cholesterol 1% w/w plus colchicine 2 mg/kg body weight. Blood was collected for biochemical measurements and conduction of ELISA for leptin, IL-18 and insulin. Histologic examination of stained with eosin and hematoxylin aorta specimens was performed. Aortic intimal thickness was evaluated using image analysis. The statistical analysis included non-parametric tests: a) paired-sample Wilcoxon test, b) Spearman correlation coefficient and c) Kruscal-Wallis test. Results: Triglerycide levels were decreased in cholesterol plus colchicine group in the end of the experiment (p < 0.05), whereas the cholesterol group had increased levels. No statistical differences were observed in the levels of IL-18, leptin and insulin between groups. Likewise, there was neither any correlation between IL-18, leptin and intima thickness nor between IL-18 and glucose and between leptin and weight. In cholesterol and colchicine group there was a strong positive correlation between IL-18 and insulin levels in the 4th week (r s =.66, n = 10, p < 0.05), whereas in the 7th week this correlation became strong negative (r s = -.86, n = 10, p < 0.05). Finally, intima thickness in the ascending and thoracic aorta of the cholesterol and colchicine group was significantly greater than that of the other groups (p < 0.05). Conclusions: Per os administration of colchicine did not influence atherosclerosis progression in cholesterol-fed rabbits, levels of IL-18, insulin and leptin. We encountered the attenuating role of colchicine on TG levels. © 2017 The Author(s)