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20212
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Subject: Veterinary Surgery and Radiology × End date: 2021 × Start date: 2021 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Studies on applicability of titanium mesh cage for osteosynthesis of induced long bone segmental defects in rabbits (Oryctolagus cuniculus )
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2021-08) Raj Kumari; Das, Arup Kumar
    The present study was conducted in two phases. In the first phase suitable anaesthetic protocol, for the development of orthopaedic model in rabbits, was explored. It was conducted in twenty (20) clinically healthy adult New Zealand white rabbits (~1.5-2.0 years old), of either sex, weighing 1.5 to 2.0 kg and were arbitrarily allocated for anaesthetic protocol-1 and anaesthetic protocol-2 containing 10 rabbits in each protocol. The common features included in these two anaesthetic protocols that premedication and induction agents along with dose rate were kept similar and an interval of five minutes was kept between each of these injections. Afterwards anaesthesia was maintained by sevoflurane in rabbits of protocol-1 and with isoflurane in rabbits of protocol-2. On the basis of evaluation of anaesthesia related parameters - sevoflurane was found relatively a better maintenance anaesthetic agent. Thereafter sevoflorane was used during the model development and surgical repair of left tibial midshaft segmental defects (LBSDs). In the second phase of study sixteen (16) adult New Zealand white rabbits (~1.5-2.0 years old) of either sex, weighing 1.5 to 2.5 kg were selected and were divided randomly into two groups (A and B) with eight animals in each group. In these rabbits LBSDs were created and cylindrical Ti-mesh cages and full length intramedullary Ti K-wire were used as implants for osteosynthesis. In rabbits of Group-B Ti-mesh cages were filled with HA ladened Mg-gelatin-collagen-spacer. On the basis of evaluation of parameters, better wound healing was observed in rabbits of Group-B compared to Group-A rabbits. Evaluation of biochemical parameters also showed greater intensity in healing of LBSDs of Group-B. The radiological parameters showed faster rate of new bone formation, reduction in gap (1.00 cm) and remodeling of segmental defect in rabbits of Group- B. On gross observations of segmental defect at the test limb it was found that a clear visible new bone bridging the entire defect and was closely integrated with the proximal and distal host bone-cage junction was observed in Group-B rabbits. However a slightly visible gap was observed in Group -A animals of this study. Although in both the groups the implant materials remained completely stable and in correct alignment that might have adequately aided in process fracture healing. The findings of histopathological and tetracycline labeling were also corroborating the findings of clinical and radiological parameters. Conclusively a better fracture healing and bridging of critical size defect was observed in rabbits of Group B as compared to Group -A rabbits and it can be stated that spacer used in this group might have aided for it and possessing attributes of osteogenicity, biodegradibity and biocompatability. In summated form it can be stated that the outcome of surgical management of large segmental defects of the tibia using cylindrical titanium mesh cages has advantages of comparative simplicity and versatility. So it has the scope to be used for the treatment of long segmental bone defects in clinical veterinary practice. However, further clinical studies are required in order to evaluate of its efficacy.
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    ThesisItemOpen Access
    Studies on regenerative potential of bone marrow derived differentiated osteoblasts and their gene expression in fracture repair in rabbit model
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2021-03) Bhatt, Jyotsana; Jadon, Narendra S.
    The present study was conducted to evaluate regenerative potential of bone marrow derived differentiated osteoblast along with β-TCP scaffold in augmenting fracture healing in rabbits and to delineate expression profile of various genes involved in fracture repair as molecular markers of healing via Real time-PCR. During first phase of study isolation and propagation of bone marrow derived MSCs, its differentiation into osteoblasts and their characterization utilizing specific techniques was done followed by second phase of clinical evaluation of therapeutic potential of undifferentiated MSCs and differentiated osteoblasts in fracture repair in rabbit model. Thirty six rabbits used in this study were randomly divided into four equal groups (A, B, C and D) having 9 animals each. Animals were anaesthetized with xylazine @ 6mg/kg followed by ketamine @ 60mg/kg, intramuscularly and a 7mm segmental defect was created in mid diaphysis of left radius bone. Animals of different groups were subjected to different treatment protocols. Animals of group I kept as negative control and only external splint was applied. In animals of group II, only β- TCP implant was used to bridge the segmental defect. Animals of group III were treated with undifferentiated MSCs along with β- TCP implant and animals of group IV were treated with differentiated osteoblasts along with β- TCP implant. Quality of fracture repair was assessed by clinical parameters, radiography, estimation of biochemical parameters, gross evaluation of test bone, histopathology, histochemistry using Van Gieson’s staining, flourochrome labelling, scanning electron microscopy and molecular assessment of bone turnover markers via Real time-PCR. Radiographic findings, gross evaluation of test bone and histopathology revealed that the key criteria for evaluating bone healing like level of callus formation, bony union between cut ends and bone remodelling were significantly (P<0.05) prominent in animals of group IV treated with differentiated osteoblasts along with β-TCP implant closely followed by animals of group III treated with undifferentiated MSCs along with β-TCP implant. Biochemical parameters showed significant (P<0.05) increase in its level on day 30 postoperatively in all the groups, however these values returned to normal level at day 45 in group III and IV signifying faster pace of healing in stem cell treated groups. Tetracycline labelling and scanning electron microscopic study of regenerated tissue from different groups of animals revealed significantly (P<0.05) superior quality of healing in animals of group IV. Gene expression profiling showed upregulation of osteopontin and osteocalcin genes, associated with remodelling, in animals of group IV whereas genes like alkaline phosphatise and collagen type-1, associated with proliferative stage of fracture healing, were upregulated in animals of group I. Results of this study reveals that animals treated with osteogenically predifferentiated MSCs (osteoblasts) showed rapid and superior quality healing of critical sized segmental bone defects as compared to animals treated with undifferentiated MSCs, β-TCP implant alone and control animals.