Role of tissue engineered collagen based tridimensional implant on the healing response of the experimentally induced large Achilles tendon defect model in rabbits: a long term study with high clinical relevance

Background

Tendon injury is one of the orthopedic conditions poses with a significant clinical challenge to both the surgeons and patients. The major limitations to manage these injuries are poor healing response and development of peritendinous adhesions in the injured area. This study investigated the effectiveness of a novel collagen implant on tendon healing in rabbits.

Results

Seventy five mature White New-Zealand rabbits were divided into treated (n = 55) and control (n = 20) groups. The left Achilles tendon was completely transected and 2 cm excised. The defects of the treated animals were filled with collagen implants and repaired with sutures, but in control rabbits the defects were sutured similarly but the gap was left untreated. Changes in the injured and normal contralateral tendons were assessed weekly by measuring the diameter, temperature and bioelectrical characteristics of the injured area. Clinical examination was done and scored. Among the treated animals, small pilot groups were euthanized at 5, 10, 15, 20, 30, 40 and 60 (n = 5 at each time interval) and the remainder (n = 20) and the control animals at 120 days post injury (DPI). The lesions of all animals were examined at macroscopic and microscopic levels and the dry matter content, water delivery and water uptake characteristics of the lesions and normal contralateral tendons of both groups were analyzed at 120 DPI.No sign of rejection was seen in the treated lesions. The collagen implant was invaded by the inflammatory cells at the inflammatory phase, followed by fibroplasia phase in which remnant of the collagen implant were still present while no inflammatory reaction could be seen in the lesions. However, the collagen implant was completely absorbed in the remodeling phase and the newly regenerated tendinous tissue filled the gap. Compared to the controls, the treated lesions showed improved tissue alignment and less peritendinous adhesion, muscle atrophy and fibrosis. They also showed significantly better clinical scoring, indices for water uptake and water absorption, and bioelectrical characteristics than the controls.

Conclusion

This novel collagen implant was biodegradable, biocompatible and possibly could be considered as a substitute for auto and allografts in clinical practice in near future.     

Synthesis,development, characterization and effectiveness of bovine pure platelet gel‐collagen‐polydioxanone bioactive graft on tendon healing

Bovine platelet gel (BPG) is an accessible and cost‐effective source of growth factors which may have a value in tendon regenerative medicine. We produced a collagen implant (CI) as a tendon proper, covered it with polydioxanone (PDS) sheath to simulate paratenon and finally embedded the BPG as an active source of growth factor within the bioimplant to test whether BPG would be able to accelerate and enhance tendon regeneration and repair. After in vitro characterization of the bioactive grafts, the grafts were implanted in rabbit large tendon defect model. Untreated tendons and tendons treated with either CI or CI‐PDS were served as controls for the CI‐PDS‐BPG. The animals were investigated clinically, ultrasonographically and haematologically for 120 days. After euthanasia, dry matter content, water uptake and delivery characteristics and also gross morphological, histopathological and scanning electron microscopic features of the healing tendons were assessed. In vitro, the activated platelets in the scaffold, released their growth factors significantly more than the controls. BPG also increased cell viability, and enhanced cellular differentiation, maturation and proliferation inside the CI‐PDS compared with the controls. In vivo, the BPG modulated inflammation, increased quality and rate of fibroplasia and produced a remodelled tendon that had significantly higher collagen content and superior collagen fibril and fibre differentiation than controls. Treatment also significantly improved tendon water uptake and delivery characteristics, animals’ serum PDGF level, CI‐PDS biocompatibility and biodegradability and reduced peritendinous adhesions, muscle fibrosis and atrophy. BPG was effective on tendon healing and CI‐PDS‐BPG may be a valuable bioscaffold in tendon reconstructive surgery.     

The Effects of Injury Preventive Warm-Up Programs on Knee Strength Ratio in Young Male Professional Soccer Players

Purpose

We aimed to investigate the effect of FIFA 11+ (11+) and HarmoKnee injury preventive warm-up programs on conventional strength ratio (CSR), dynamic control ratio (DCR) and fast/slow speed ratio (FSR) in young male professional soccer players. These ratios are related to the risk of injury to the knee in soccer players.

Methods

Thirty-six players were divided into 3 groups; FIFA 11+, HarmoKnee and control (n = 12 per group). These exercises were performed 3 times per week for 2 months (24 sessions). The CSR, DCR and FSR were measured before and after the intervention.

Results

After training, the CSR and DCR of knee muscles in both groups were found to be lower than the published normal values (0.61, 0.72, and 0.78 during 60°.s⁻¹, 180°.s⁻¹ and 300°.s⁻¹, respectively). The CSR (60°.s⁻¹) increased by 8% and FSR in the quadriceps of the non-dominant leg by 8% in the 11+. Meanwhile, the DCR in the dominant and non-dominant legs were reduced by 40% and 30% respectively in the 11+. The CSR (60°.s⁻¹) in the non-dominant leg showed significant differences between the 11+, HarmoKnee and control groups (p = 0.02). As for the DCR analysis between groups, there were significant differences in the non-dominant leg between both programs with the control group (p = 0.04). For FSR no significant changes were found between groups.

Conclusions

It can be concluded that the 11+ improved CSR and FSR, but the HarmoKnee program did not demonstrate improvement. We suggest adding more training elements to the HarmoKnee program that aimed to enhance hamstring strength (CSR, DCR and FSR). Professional soccer players have higher predisposition of getting knee injuries because hamstring to quadriceps ratio were found to be lower than the average values. It seems that the 11+ have potentials to improve CSR and FSR as well as prevent knee injuries in soccer players.     

Nitrile-metabolizing potential of Bacillus cereus strain FA12; Nitrilase production,purification, and characterization

Nitrile-hydrolyzing bacteria have the potential to perform useful biotransformations such as the production of industrially useful acids and amides. In this study, we report a nitrile-degrading bacterium with significant nitrile metabolism. Molecular characterization of 16S rDNA gene characterized this strain as Bacillus cereus. Medium optimization of B. cereus FA12 showed that biomass and nitrilase production was strongly supported by glucose (10 gL^{? 1}) and yeast extract (10 gL^{? 1}). Enzymatic production improved slightly in the pH range from 6.0 to 7.0. The addition of Mg⁺², Fe⁺², and Na⁺ supported biomass and nitrilase production; however, other metal ions, Co⁺² and Cu⁺², inhibited production. The apparent molecular mass of the puri?ed FA12 nitrilase as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was about 45 kDa. Nitrilase FA12 shows relatively high activity and stability at pH 7.0 and 40°C. Nitrilase FA12 was marginally inhibited with Ca^{+ 2} and Co⁺², whereas inhibition in the presence of dithiothreitol or DTT was 80%. The pseudo K_m (mM) values of resting cells (i.e., treating whole cells as if they were an enzyme) for acetonitrile and acetamide were determined to be 2.36 and 1.81, respectively. Under optimum situations, B. cereus FA12 resting cells produced 83 and 58 (U/mg) acetonitrile/acetamide degrading activity, respectively. Ammonia production from acetamide and acetonitrile by the B. cereus FA12 was maximum after 5 and 7 h of incubation, respectively. These results indicate that B. cereus FA12 resting cells may be used in nitrile biotransformations to produce commercially useful compounds.     

The Effects of Comprehensive Warm-Up Programs on Proprioception,Static and Dynamic Balance on Male Soccer Players

Purpose

The study investigated the effects of FIFA 11+ and HarmoKnee, both being popular warm-up programs, on proprioception, and on the static and dynamic balance of professional male soccer players.

Methods

Under 21 year-old soccer players (n = 36) were divided randomly into 11+, HarmoKnee and control groups. The programs were performed for 2 months (24 sessions). Proprioception was measured bilaterally at 30°, 45° and 60° knee flexion using the Biodex Isokinetic Dynamometer. Static and dynamic balances were evaluated using the stork stand test and Star Excursion Balance Test (SEBT), respectively.

Results

The proprioception error of dominant leg significantly decreased from pre- to post-test by 2.8% and 1.7% in the 11+ group at 45° and 60° knee flexion, compared to 3% and 2.1% in the HarmoKnee group. The largest joint positioning error was in the non-dominant leg at 30° knee flexion (mean error value = 5.047), (p<0.05). The static balance with the eyes opened increased in the 11+ by 10.9% and in the HarmoKnee by 6.1% (p<0.05). The static balance with eyes closed significantly increased in the 11+ by 12.4% and in the HarmoKnee by 17.6%. The results indicated that static balance was significantly higher in eyes opened compared to eyes closed (p = 0.000). Significant improvements in SEBT in the 11+ (12.4%) and HarmoKnee (17.6%) groups were also found.

Conclusion

Both the 11+ and HarmoKnee programs were proven to be useful warm-up protocols in improving proprioception at 45° and 60° knee flexion as well as static and dynamic balance in professional male soccer players. Data from this research may be helpful in encouraging coaches or trainers to implement the two warm-up programs in their soccer teams.     

Electrochemical studies of DNA immobilization onto the azide-terminated monolayers and its interaction with taxol

A surface modification procedure for the creation of self-assembled monolayers (SAMs) that can be used as a scaffold for double-stranded DNA (dsDNA) incorporation onto the gold surfaces is described. The SAMs of an azidohexane thiol derivative were prepared on the Au electrode and then used for the immobilization of dsDNA. The electrochemical characteristics of dsDNA onto the SAM-modified gold electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy, and the surface concentration of dsDNA onto the SAMs surface was estimated. The interaction of dsDNA with the anticancer drug, taxol (paclitaxel), was also studied on the surface of DNA/SAM/Au electrode. The observed decrease in the guanine oxidation peak current was used to monitor the interaction of taxol with DNA. The resulting Langmuir isotherm for taxol binding to DNA at the modified electrode was used to evaluate the binding constant of taxol-DNA. The results obtained supported the groove binding interaction of taxol with DNA. The modified electrode was used as a sensitive sensor for quantification of taxol in human serum sample.     

Phylogeography and evolutionary history of reassortant H9N2 viruses with potential human health implications

Avian influenza viruses of the H9N2 subtype have seriously affected the poultry industry of the Far and Middle East since the mid-1990s and are considered one of the most likely candidates to cause a new influenza pandemic in humans. To understand the genesis and epidemiology of these viruses, we investigated the spatial and evolutionary dynamics of complete genome sequences of H9N2 viruses circulating in nine Middle Eastern and Central Asian countries from 1998 to 2010. We identified four distinct and cocirculating groups (A, B, C, and D), each of which has undergone widespread inter- and intrasubtype reassortments, leading to the generation of viruses with unknown biological properties. Our analysis also suggested that eastern Asia served as the major source for H9N2 gene segments in the Middle East and Central Asia and that in this geographic region within-country evolution played a more important role in shaping viral genetic diversity than migration between countries. The genetic variability identified among the H9N2 viruses was associated with specific amino acid substitutions that are believed to result in increased transmissibility in mammals, as well as resistance to antiviral drugs. Our study highlights the need to constantly monitor the evolution of H9N2 viruses in poultry to better understand the potential risk to human health posed by these viruses.     

Analysis of Jumping-Landing Manoeuvers after Different Speed Performances in Soccer Players

PurposeRunning at high speed and sudden change in direction or activity stresses the knee. Surprisingly, not many studies have investigated the effects of sprinting on knee’s kinetics and kinematics of soccer players. Hence, this study is aimed to investigate indices of injury risk factors of jumping-landing maneuvers performed immediately after sprinting in male soccer players.MethodsTwenty-three collegiate male soccer players (22.1±1.7 years) were tested in four conditions; vertical jump (VJ), vertical jump immediately after slow running (VJSR), vertical jump immediately after sprinting (VJFR) and double horizontal jump immediately after sprinting (HJFR). The kinematics and kinetics data were measured using Vicon motion analyzer (100Hz) and two Kistler force platforms (1000Hz), respectively.ResultsFor knee flexion joint angle, (p = 0.014, η = 0.15) and knee valgus moment (p = 0.001, η = 0.71) differences between condition in the landing phase were found. For knee valgus joint angle, a main effect between legs in the jumping phase was found (p = 0.006, η = 0.31), which suggests bilateral deficit existed between the right and left lower limbs.ConclusionIn brief, the important findings were greater knee valgus moment and less knee flexion joint angle proceeding sprint (HJFR & VJFR) rather than no sprint condition (VJ) present an increased risk for knee injuries. These results seem to suggest that running and sudden subsequent jumping-landing activity experienced during playing soccer may negatively change the knee valgus moment. Thus, sprinting preceding a jump task may increase knee risk factors such as moment and knee flexion joint angle.     

The effects of gelatin,fibrin-platelet glue and their combination on healing of the experimental critical bone defect in a rat model: radiological,histological, scanning ultrastructural and biomechanical evaluation

Fibrin-platelet glue (FPG) is a blood derivative, in which platelets and fibrinogen are concentrated in a small plasma volume, by differential centrifugation and precipitation. It can form a three-dimensional and biocompatible fibrin scaffold with a myriad of growth factors and proteins that are released progressively to the local environment and contribute to the accelerated postoperative bone healing. Gelatin (Gel) is a derivative of collagen and can promote cell adhesion and proliferation due to its unique sequence of amino acids, so it is suitable for bone tissue applications. This study examined the effects of Gel, FPG and their combinations as bone scaffold on the healing of surgically created critical-size defects in rat radius. Fifty critical size defects of 5 mm long were bilaterally created in the radial diaphysis of 25 rats. The animals were randomly divided into five equal groups as empty defect, autograft, Gel, FPG and Gel–FPG groups (n = 10 in each group). Radiographs of each forelimb were taken postoperatively on the 1st day and then at the 28th and 56th days post injury to evaluate bone formation, union and remodeling of the defect. After 56 days, the rats were euthanized and their harvested healing bone samples were evaluated by histopathology, scanning electron microscopy (SEM) and biomechanical testing. The results of present study showed that the Gel alone did not significantly affect bone healing and regeneration; however, the Gel treated defects promoted healing more than those that were left untreated (negative control). Furthermore, the FPG-enhanced grafts provided a good scaffold containing numerous growth factors for proliferation of osteoinduction and was effective in improving the structural and functional properties of the newly formed bone more than that of the untreated and also the Gel treated groups. Incorporation of Gel into the FPG scaffold improved healing potential of the FPG scaffold; however, it was still inferior to the autograft (positive control). Although the Gel–FPG scaffolds had best effectiveness during bone regeneration, it still needs to be further enhanced by incorporation of the ceramic and osteoinductive biomaterials.