scholarly journals Self-Repair of Rat Cortical Bone Microdamage after Fatigue Loading In Vivo

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Bo Wu ◽  
Chan Zhang ◽  
Bo Chen ◽  
Ling Zhang ◽  
Ruchun Dai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fatigue Loading ◽  
Repair Process ◽  
The Self ◽  
Parameter Analysis ◽  
Ovariectomized Rats ◽  
Four Point Bending ◽  
Bone Microdamage ◽  
Self Repair

Bone microdamage can be repaired through bone remodeling induced by loading. In this study, a loading device was developed for improved efficiency and the self-repair process of bone microdamage was studied in ovariectomized rats. First, four-point bending fixtures capable of holding two live rats simultaneously were designed. Rats were loaded and subjected to a sinusoidal wave for 10,000 cycles. They were then divided into four groups to evaluate time points from 1 to 4 weeks in the microdamage repair process. The loaded right ulna was used for microdamage parameter analysis, and the loaded right radius was tested for mechanical properties. In all groups, microdamage consisted primarily of microcracks, which were observed in bone surrounding the force-bearing point. The values of the microdamage parameters were significantly lower at 3 weeks than at 2 weeks. However, none of the differences in mechanical properties between any four groups were statistically significant. This study shows that the improved application of loading in the form of bending for double-rat simultaneous administration was practical and efficient. These results suggest that microdamage was repaired between 2 weeks to 3 weeks after fatigue damage and microdamage is a more sensitive index of bone quality than mechanical properties.

scholarly journals Endogenous Galectin-3 is Required for Skeletal Muscle Repair

2020 ◽  
Author(s):  
Daniel Giuliano Cerri ◽  
Lilian Cataldi Rodrigues ◽  
Vani Maria Alves ◽  
Juliano Machado ◽  
Víctor Alexandre Félix Bastos ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cell Culture ◽  
Molecular Mechanisms ◽  
Repair Process ◽  
Muscle Repair ◽  
Galectin 3 ◽  
Self Repair ◽  
Myoblast Cell

ABSTRACTSkeletal muscle has the intrinsic ability to self-repair through a multifactorial process, but many aspects of its cellular and molecular mechanisms are not fully understood. There is increasing evidence that some members of the mammalian β-galactoside-binding protein family (galectins) are involved in the muscular repair process (MRP), including galectin-3 (Gal-3). However, there are many questions about the role of this protein on muscle self-repair. Here, we demonstrate that endogenous Gal-3 is required for: i) muscle repair in vivo using a chloride-barium myolesion mouse model, and ii) mouse primary myoblasts myogenic programming. Injured muscle from Gal-3 knockout mice (GAL3KO) showed persistent inflammation associated with compromised muscle repair and the formation of fibrotic tissue on the lesion site. In GAL3KO mice, osteopontin expression remained high even after 7 and 14 days of the myolesion, while MyoD and myogenin had decreased their expression. In GAL3KO mouse primary myoblast cell culture, Pax7 detection seems to sustain even when cells are stimulated to differentiation and MyoD expression is drastically reduced. These findings suggest that the detection and temporal expression levels of these transcriptional factors appear to be altered in Gal-3-deficient myoblast cell culture compared to Wild Type (WT) cells. We observed Gal-3 expression in WT states, both in vivo and in vitro, in sarcoplasm/cytoplasm and myonuclei; as differentiation proceeds, Gal-3 expression is drastically reduced, and its location is confined to the sarcolemma/plasma cell membrane. We also observed a change in the temporal-spatial profile of Gal-3 expression and muscle transcription factors levels during the myolesion. Overall, these results demonstrate that endogenous Gal-3 is required for the skeletal muscle repair process.

Smart Molecules: Organization and Morphology of the Self-Assembled Collagen Fibrils Formed From a Solution of Densly Packed Collagen Monomers

2008 ◽  
Author(s):  
Nima Saeidi ◽  
Jeffrey W. Ruberti
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Liquid Crystalline ◽  
Alternative Hypothesis ◽  
Collagen Fibrils ◽  
The Self ◽  
Collagen Molecules ◽  
Cholesteric Liquid Crystalline

Load-bearing tissues owe their mechanical properties to the presence of highly-organized arrays of collagen fibrils. Aligned lamellae in cornea and aligned fascicles in tendon are the best examples of collagen fibrillar organization at the macroscopic level. The process by which collagen is organized in the extracellular matrix (ECM) is still unclear. But it is generally thought to be facilitated locally via “fibripositors” or cell surface “crypts”. According to this theory, fibroblasts create bounded “compartments” in the ECM through which they deposit organized groups of fibrils (in the form of lamellae in the cornea and in the form of fascicles in the tendon) [1, 2]. An alternative hypothesis proposed by Marie Giraud-Guille suggests that fibroblasts concentrate collagen monomers to form cholesteric liquid crystalline patterns that resemble those found in collagenous matrices in vivo [3–8]. Such organization has been demonstrated in vitro using extracted collagen monomers. However, the data presented in these studies focuses principally on the alignment of the collagen molecules and not on the organization and resulting morphology of condensed collagen fibrils. Considering that matrix mechanical properties in vivo are the result of the fibrillar alignment and not the alignment of individual molecules, further investigation of cholesterically organized condensed fibrils and their morphology is necessary.

Mechanical properties and in-vivo performance of calcium phosphate cement—chitosan fibre composite

2008 ◽  
Vol 222 (3) ◽  
pp. 347-353 ◽  
Author(s):  
Q Lian ◽  
D-C Li ◽  
J-K He ◽  
Z Wang
Keyword(s):  
Mechanical Properties ◽  
Calcium Phosphate ◽  
Calcium Phosphate Cement ◽  
Bone Repair ◽  
Fibre Composite ◽  
Repair Process ◽  
Fibre Volume ◽  
Dimensional Structure ◽  
Fibre Structure

Self-hardened calcium phosphate cement (CPC) sets to form hydroxyapatite and possesses excellent osteoconductivity. However, lack of macroporosity and low strength constrain its application in bone tissue engineering. Recent studies have incorporated various fibres into CPC to improve its mechanical strength. The present approach focused on the reinforcement of CPC with chitosan fibres and then the effects of the fibre structure on the mechanical properties and macrochannels formation characteristics of CPC—fibre composite were investigated. Chitosan fibres of diameter 200 μm were used to fabricate two types of three-dimensional structure, which were then coated with collagen and incorporated into CPC to fabricate CPC—fibre implants with a fibre volume content of 5 per cent. The compressive strength of the CPC—fibre implant was 33 MPa when the strain was 2.4 per cent, which is fourfold higher than that of the CPC control. Nine cylindrical implants including six CPC—fibre implants were implanted in the bone defects of nine dogs and were then post-operatively observed. After 20 weeks in vivo, new callus from the healthy tissue of the defect entirely integrated with the CPC—fibre implant and new bone was formed as the implant degraded. Scanning electronic microscopy images indicated that macrochannels were formed in the CPC—fibre implants with the degradation of fibres, but only micropores with a scale of less than 50 μm could be observed in the CPC control. Briefly, the incorporation of a suitable chitosan-fibre structure into a CPC implant not only could improve its mechanical properties but also facilitated the bone repair process in vivo.

Computational Study of Thymine Dimer Radical Anion Splitting in the Self-Repair Process of Duplex DNA

2008 ◽  
Vol 130 (11) ◽  
pp. 3443-3450 ◽  
Author(s):  
Fanny Masson ◽  
Teodoro Laino ◽  
Ivano Tavernelli ◽  
Ursula Rothlisberger ◽  
Jürg Hutter
Keyword(s):  
Radical Anion ◽  
Computational Study ◽  
Repair Process ◽  
The Self ◽  
Duplex Dna ◽  
Thymine Dimer ◽  
Self Repair

scholarly journals Effect of diosgenin, a steroidal sapogenin, on the rat skeletal system.

2016 ◽  
Vol 63 (2) ◽  
Author(s):  
Joanna Folwarczna ◽  
Maria Zych ◽  
Barbara Nowińska ◽  
Maria Pytlik ◽  
Magdalena Bialik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bone Formation ◽  
Cancellous Bone ◽  
Compact Bone ◽  
Estrogen Deficiency ◽  
Ovariectomized Rats ◽  
Skeletal System ◽  
Steroidal Sapogenin

Diosgenin is a steroidal sapogenin present in fenugreek and Dioscorea spp. as glycosides (saponins). Diosgenin has already been reported to inhibit osteoclastogenesis and to stimulate osteogenic activity of osteoblastic cells in vitro, and to exert some antiosteoporotic effects in rats in vivo. The aim of the present study was to investigate the effects of diosgenin administration on the skeletal system of rats with normal estrogen level and with estrogen deficiency induced by bilateral ovariectomy. The experiments were carried out on 3-month-old non-ovariectomized and ovariectomized Wistar rats, divided into control rats and rats receiving diosgenin (50 mg/kg p.o. daily) for 4 weeks. Serum bone turnover markers, bone mass and mineralization, histomorphometric parameters and mechanical properties were studied. Diosgenin improved some investigated parameters in both non-ovariectomized and ovariectomized rats, in which estrogen deficiency induced osteoporotic changes. Diosgenin increased compact bone formation and probably inhibited cancellous bone resorption, which led to improvement of mechanical properties of compact and cancellous bone. In conclusion, this in vivo study demonstrated that diosgenin may be one of sparse compounds increasing bone formation.

scholarly journals Application of Finite Element Analysis in Oral and Maxillofacial Surgery—A Literature Review

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3063 ◽  
Author(s):  
Magdalena Lisiak-Myszke ◽  
Dawid Marciniak ◽  
Marek Bieliński ◽  
Hanna Sobczak ◽  
Łukasz Garbacewicz ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Maxillofacial Surgery ◽  
Parameter Analysis ◽  
Oral And Maxillofacial Surgery ◽  
Element Analysis ◽  
Reconstructive Operations ◽  
Long Time

In recent years in the field of biomechanics, the intensive development of various experimental methods has been observed. The implementation of virtual studies that for a long time have been successfully used in technical sciences also represents a new trend in dental engineering. Among these methods, finite element analysis (FEA) deserves special attention. FEA is a method used to analyze stresses and strains in complex mechanical systems. It enables the mathematical conversion and analysis of mechanical properties of a geometric object. Since the mechanical properties of the human skeleton cannot be examined in vivo, a discipline in which FEA has found particular application is oral and maxillofacial surgery. In this review we summarize the application of FEA in particular oral and maxillofacial fields such as traumatology, orthognathic surgery, reconstructive surgery and implantology presented in the current literature. Based on the available literature, we discuss the methodology and results of research where FEA has been used to understand the pathomechanism of fractures, identify optimal osteosynthesis methods, plan reconstructive operations and design intraosseous implants or osteosynthesis elements. As well as indicating the benefits of FEA in mechanical parameter analysis, we also point out the assumptions and simplifications that are commonly used. The understanding of FEA’s opportunities and advantages as well as its limitations and main flaws is crucial to fully exploit its potential.

The self-priming action of LHRH is under negative FSH control through a factor released by the ovary: observations in female rats in vivo

1991 ◽  
Vol 129 (2) ◽  
pp. 205-211 ◽  
Author(s):  
D. W. Koppenaal ◽  
A. M. I. Tijssen ◽  
J. A. M. J. van Dieten ◽  
J. de Koning
Keyword(s):  
Priming Effect ◽  
Oestrous Cycle ◽  
The Self ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Menopausal Women ◽  
Lh Release ◽  
Urinary Fsh

ABSTRACT Female rats were treated with Metrodin (highly purified urinary FSH from menopausal women) or saline during the oestrous cycle. On the day of pro-oestrus they were anaesthesized with phenobarbital and received four repetitive LHRH injections 1 h apart. This treatment with FSH suppressed the unprimed LH response to the first LHRH injection. During the subsequent injections the maximal LHRH self-priming was delayed by 3 h till the fourth LHRH stimulation. At this time, LH release in response to LHRH was equally as high as shown in the saline controls after the second LHRH injection. Ovariectomized rats did not show the self-priming effect and FSH treatment was ineffective in suppressing LHRH-induced LH release. Administration of FSH followed by an additional 4- or 24-h period before LHRH stimulation were equally effective in suppressing the unprimed LH release and delaying (up to 3 h) the maximal priming of LH release by LHRH. Even 4–20-fold increased amounts of LHRH did not affect the suppressed unprimed release of LH after FSH treatment. Treatment with FSH did not change oestradiol and progesterone levels. It was concluded that FSH treatment suppresses the unprimed LHRH-induced LH release and delays maximal LHRH self-priming by enhancing the release of an ovarian factor. Journal of Endocrinology (1991) 129, 205–211

Hierarchies of damage induced loss of mechanical properties in calcified bone after in vivo fatigue loading of rat ulnae

2011 ◽  
Vol 4 (6) ◽  
pp. 841-848 ◽  
Author(s):  
J. Macione ◽  
N.B. Kavukcuoglu ◽  
R.S.A. Nesbitt ◽  
A.B. Mann ◽  
N. Guzelsu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fatigue Loading
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