Radioprotection of Tendon Tissue via Crosslinking and Free Radical Scavenging

Ionizing radiation could supplement tissue bank screening to further reduce the probability of diseases transmitted by allografts if denaturation effects can be minimized. It is important, however, such sterilization procedures be nondetrimental to tissues. We compared crosslinking and free radical scavenging potential methods to accomplish this task in tendon tissue. In addition, two forms of ionizing irradiation, gamma and electron beam (e-beam), were also compared. Crosslinkers included 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and glucose, which were used to add exogenous crosslinks to collagen. Free radical scavengers included mannitol, ascorbate, and riboflavin. Radioprotective effects were assessed through tensile testing and collagenase resistance testing after irradiation at 25 kGy and 50 kGy. Gamma and e-beam irradiation produced similar degenerative effects. Crosslinkers had the highest strength at 50 kGy, EDC treated tendons had 54% and 49% higher strength than untreated, for gamma and e-beam irradiation respectively. Free radical scavengers showed protective effects up to 25 kGy, especially for ascorbate and riboflavin. Crosslinked samples had higher resistance to collagenase and over a wider dose range than scavenger-treated. Of the options studied, the data suggest EDC precrosslinking or glucose treatment provides the best maintenance of native tendon properties after exposure to ionizing irradiation. One or more of the authors (MGD) have received funding from the Musculoskeletal Transplant Foundation Peer Reviewed Scientific Grants Program (January–December 2005).     

In vitro study of the role of various preservation methods on mechanical properties of allografts of the patellar tendon]

Tendon allografts are presently used for surgical reconstruction of the anterior cruciate ligament. The aim of this study was the in vitro evaluation of the modification of the mechanical properties of conserved human patellar tendons, deep-frozen or freeze-dried and sterilized with gamma rays. Thirty pairs of patellar tendons (central third) with their bony attachments were removed from fresh corpses, frozen in liquid nitrogen, then conserved at -80 degrees C. Out of each pair, one tendon was submitted to an additional treatment and the other was used as a control. Three types of treatment were studied: 2.5 Mrad irradiation (groupe I), freeze-drying with 1% residual humidity (groupe II), consecutive freeze-drying and irradiation (group III). After warming up (controls and group I treated tendons), the specimens were submitted to mechanical tests on the pulling machine with a suitable arrangement. Two types of tests were performed: a creep test (80 cycles at 1 Hz between 0 and 50 N) then an ultimate tensile strength test (0.25 mm/s). Freeze-drying causes macroscopic morphological alterations, which are even more marked if irradiation is applied in addition. The three types of treatment induce an increase in creep and a decrease in the ultimate, tensile strength and in Young's module, all being statistically significant. The three types of treatment alter the mechanical properties of the allograft. Freeze-drying maintains a better resistance of the graft. The combination of freeze-drying and irradiation is the most damaging method, and freeze-drying even seems to potentialize the harmful effects of irradiation resistance (group II freeze-dried grafts), the treated allografts present with changes in their viscoelastic properties that are incompatible with their clinical use. This study has also shown that some parameters influence the extent of the damaging effects of these three treatments, and experiments are being continued to optimize the conservation and sterilization procedure.     

Effects of solvent preservation with or without gamma irradiation on the material properties of canine tendon allografts

We studied the effects of solvent preservation with and without gamma irradiation on the material properties and morphology of canine tendons. Twenty-four paired tendons were harvested from both hind limbs of eight dogs. The tendons from the right legs were divided into three treatment groups of eight tendons each. In the first group, the tendons were subjected to solvent preservation for sterilization and drying (solvent group). In the second group, the tendons were treated in the same manner and then were sterlized by gamma irradiation (solvent/gamma group). The same treatments were applied to the tendons in the third group but in reverse order (gamma/solvent group). Tendons from the contralateral left legs were frozen immediately for use as controls for each corresponding treatment group. Histologically, the tendons treated with solvent, with or without gamma irradiation, had a more prominent wavy pattern in the collagen fibers than the control tendons. Mechanically, the tangent moduli for the solvent, solvent/gamma, and gamma/solvent groups were 58.53, and 99%, respectively, of each contralateral control. The respective tensile strengths were 85, 39, and 86% of that of the contralateral control. The tendons in the solvent/gamma group underwent the most severe changes in material properties: the tendons in the gamma/solvent group changed the least. This suggests that gamma irradiation followed by solvent drying is the procedure of choice for the preservation of tendon allografts.     

Fatigue crack propagation resistance of highly crosslinked polyethylene

A higher degree of cross-linking has been shown to improve wear properties of ultra-high molecular weight polyethylene in laboratory studies. However, cross-linking can also affect the mechanical properties of ultra-high molecular weight polyethylene. Fatigue crack propagation resistance was determined for electron beam cross-linked ultra-high molecular weight polyethylene and compared with gamma irradiation cross-linked and noncross-linked polyethylene fatigue specimens. Crosslinking was done with different dosages of irradiation followed by melting. For one irradiation dose (50 kGy) extrusion and molding processes were compared. A fracture mechanics approach was used to determine how the degree of cross-linking affects resistance to crack propagation in ultra-high molecular weight polyethylene. Fatigue crack propagation resistance was reduced in proportion to the irradiation dose. The type of irradiation (gamma or electron beam) or manufacturing method (extrusion or molding) did not affect fatigue crack propagation resistance. The reduced fatigue strength of highly cross-linked ultra-high molecular weight polyethylene could lead to mechanical failure in conditions that are associated with cyclic local tensile stresses.     

Effect of postoperative irradiation on free skin flaps: an experimental study in rats.

The modern treatment of musculoskeletal malignant tumours often requires different combinations of surgery, chemotherapy, and radiotherapy. Although combination treatments have allowed reconstruction of more complex defects, the risk of complications also rises. In clinical series the complication rate is influenced by the characteristics of the defect and the quality of the radiation used. The flap survival is high, but the overall complication rate is more than 25%. In this study we looked at the healing of microvascular free skin flaps exposed to postoperative irradiation in a rat model. Epigastric microvascular free skin flap were exposed to a single dose of 20 Gy radiation one week postoperatively (n = 8). A comparison was made with free epigastric skin flaps without postoperative radiation (n = 8). The healing was assessed histologically at four weeks and by measuring the tensile strength of the wound. Biochemical total nitrogen and hydroxyproline contents were also measured. Results showed that histologically the interfaces healed similarly with only minimal histomorphological changes. Neither the mechanical strength of the healing interface nor the biochemical markers altered significantly. Postoperative irradiation with a single dose of 20 Gy does not affect the survival of free skin flaps in rats. In the future the model described could be used to study the effects of combination therapy of surgery, radiotherapy, and chemotherapy more closely to find the optimal control of malignancies with limited damage to treated tissue.     

Effect of Postoperative Irradiation on Free Skin Flaps: An Experimental Study in Rats

The modern treatment of musculoskeletal malignant tumours often requires different combinations of surgery, chemotherapy, and radiotherapy. Although combination treatments have allowed reconstruction of more complex defects, the risk of complications also rises. In clinical series the complication rate is influenced by the characteristics of the defect and the quality of the radiation used. The flap survival is high, but the overall complication rate is more than 25%. In this study we looked at the healing of microvascular free skin flaps exposed to postoperative irradiation in a rat model. Epigastric microvascular free skin flap were exposed to a single dose of 20 Gy radiation one week postoperatively ( n = 8). A comparison was made with free epigastric skin flaps without postoperative radiation ( n = 8). The healing was assessed histologically at four weeks and by measuring the tensile strength of the wound. Biochemical total nitrogen and hydroxyproline contents were also measured. Results showed that histologically the interfaces healed similarly with only minimal histomorphological changes. Neither the mechanical strength of the healing interface nor the biochemical markers altered significantly. Postoperative irradiation with a single dose of 20 Gy does not affect the survival of free skin flaps in rats. In the future the model described could be used to study the effects of combination therapy of surgery, radiotherapy, and chemotherapy more closely to find the optimal control of malignancies with limited damage to treated tissue.     

Exogenous collagen cross-linking recovers tendon functional integrity in an experimental model of partial tear

We investigated the hypothesis that exogenous collagen cross-linking can augment intact regions of tendon to mitigate mechanical propagation of partial tears. We first screened the low toxicity collagen cross-linkers genipin, methylglyoxal and ultra-violet (UV) light for their ability to augment tendon stiffness and failure load in rat tail tendon fascicles (RTTF). We then investigated cross-linking effects in load bearing equine superficial digital flexor tendons (SDFT). Data indicated that all three cross-linking agents augmented RTTF mechanical properties but reduced native viscoelasticity. In contrast to effects observed in fascicles, methylglyoxal treatment of SDFT detrimentally affected tendon mechanical integrity, and in the case of UV did not alter tendon mechanics. As in the RTTF experiments, genipin cross-linking of SDFT resulted in increased stiffness, higher failure loads and reduced viscoelasticity. Based on this result we assessed the efficacy of genipin in arresting tendon tear propagation in cyclic loading to failure. Genipin cross-linking secondary to a mid-substance biopsy-punch significantly reduced tissue strains, increased elastic modulus and increased resistance to fatigue failure. We conclude that genipin cross-linking of injured tendons holds potential for arresting tendon tear progression, and that implications of the treatment on matrix remodeling in living tendons should now be investigated.     

Free radical scavenging alleviates the biomechanical impairment of gamma radiation sterilized bone tissue.

Terminal sterilization of bone allografts by gamma radiation is often essential prior to their clinical use to minimize the risk of infection and disease transmission. While gamma radiation has efficacy superior to other sterilization methods it also impairs the material properties of bone allografts, which may result in premature clinical failure of the allograft. The mechanisms by which gamma radiation sterilization damages bone tissue are not well known although there is evidence that the damage is induced via free radical attack on the collagen. In the light of the existing literature, it was hypothesized that gamma radiation induced biochemical damage to bone's collagen that can be reduced by scavenging for the free radicals generated during the ionizing radiation. It was also hypothesized that this lessening of the extent of biochemical degradation of collagen will be accompanied by alleviation in the extent of biomechanical impairment secondary to gamma radiation sterilization. Standardized tensile test specimens machined from human femoral cortical bone and specimens were assigned to four treatment groups: control, scavenger treated-control, irradiated and scavenger treated-irradiated. Thiourea was selected as the free radical scavenger and it was applied in aqueous form at the concentration of 1.5 M. Monotonic and cyclic mechanical tests were conducted to evaluate the mechanical performance of the treatment groups and the biochemical integrity of collagen molecules were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native mechanical properties of bone tissue did not change by thiourea treatment only. The effect of thiourea treatment on mechanical properties of irradiated specimens were such that the post-yield energy, the fracture energy and the fatigue life of thiourea treated-irradiated treatment group were 1.9-fold, 3.3-fold and 4.7-fold greater than those of the irradiated treatment group, respectively. However, the mechanical function of thiourea treated and irradiated specimens was not to the level of unirradiated controls. The damage occurred through the cleavage of the collagen backbone as revealed by SDS PAGE analysis. Irradiated specimens did not exhibit a noteworthy amount of intact alpha-chains whereas those irradiated in the presence of thiourea demonstrated intact alpha-chains. Results demonstrated that free radical damage is an important pathway of damage, caused by cleaving the collagen backbone. Blocking the activity of free radicals using the scavenger thiourea reduces the extent of damage to collagen, helping to maintain the mechanical strength of sterilized tissue. Therefore, free radical scavenger thiourea has the potential to improve the functional life-time of the allograft component following transplantation.     

Postoperative radiotherapy for patients with carcinoma of the prostate undergoing radical prostatectomy with positive surgical margins, seminal vesicle involvement and/or penetration through the capsule

Between 1970 and 1983, 442 patients were treated for carcinoma of the prostate at our university medical center. Of the patients 319 underwent radical prostatectomy and 159 (50 per cent) had positive surgical margins and/or seminal vesicle involvement. Of these 159 patients 46 received postoperative irradiation and the actuarial survival was 96, 90 and 90 per cent at 5, 10 and 15 years, respectively. Among the remaining 113 patients who were treated with an operation alone the corresponding figures were 82, 62 and 21 per cent, respectively (p equals 0.02). Considering deaths only of cancer, the surgery only patients had a 15-year actuarial survival of 25 per cent compared to 90 per cent for those who underwent postoperative radiotherapy (p equals 0.07). Actuarial survival free of disease for the surgery plus postoperative irradiation group at 15 years was 40 per cent compared to 28 per cent for the surgery only group (p equals 0.34). Actuarial local control in the irradiated patients was 96 per cent at 15 years versus 32 per cent for the surgery only group (p equals 0.009). Actuarial survival free of distant disease at 15 years was 42 per cent in the irradiated versus 72 per cent in the nonirradiated groups (p equals 0.104). Severe complications attributable to radiation included 3 cases of radiation cystitis, 1 patient with urinary incontinence and leg edema in 9 per cent of the patients undergoing postoperative irradiation compared to 2 per cent of those treated with radical prostatectomy only. Postoperative irradiation appears to be indicated in patients with carcinoma of the prostate who undergo radical prostatectomy and who have positive margins and/or seminal vesicle involvement. Local control is markedly improved (p equals 0.009) and actuarial survival also is benefitted. There was a trend toward decreased deaths of cancer with postoperative irradiation that approached statistical significance. Postoperative irradiation did not improve survival rates free of disease and free of distant disease over those achieved with surgery alone. This finding suggests that while postoperative irradiation may not improve the ultimate cure rate by controlling local disease, early deaths of cancer are reduced resulting in a meaningful increase in survival for these patients.     

Effect of sterilization method and other modifications on the wear resistance of acetabular cups made of ultra-high molecular weight polyethylene. A hip-simulator study

BACKGROUND: Wear of ultra-high molecular weight polyethylene acetabular cups in hip prostheses produces billions of submicrometer wear particles annually that can cause osteolysis and loosening of the components. Thus, substantial improvement of the wear resistance of ultra-high molecular weight polyethylene could extend the clinical life span of total hip prostheses. It has become apparent that the conditions under which ultra-high molecular weight polyethylene cups have been sterilized can markedly affect their long-term wear properties, and new sterilization methods and other modifications have been developed to minimize the negative effects. METHODS: In the present study, a hip-joint simulator was used to assess whether it is preferable to sterilize ultra-high molecular weight polyethylene cups without gamma irradiation, to avoid radiation-induced oxidative degradation, or to sterilize with gamma irradiation while the cups are packaged in a suitable low-oxygen atmosphere to minimize oxidation while retaining the increased wear resistance conferred by the radiation-induced cross-linking. Ion-implanted cups and cups made of a highly crystalline polyethylene (Hylamer) also were investigated. Cups made of each material were subjected to wear-testing prior to and after artificial thermal aging to accelerate oxidative degradation. RESULTS: The results of the present study demonstrated that the cross-linking induced by gamma irradiation improves the wear resistance of ultra-high molecular weight polyethylene, while oxidation reduces it. Without thermal aging, the two types of cups that were sterilized with gamma irradiation while in low-oxygen packaging exhibited about a 50 percent lower rate of wear than did either the nonsterilized cups or the nonirradiated cups sterilized with gas plasma. There was a comparable advantage in the rate of wear after fourteen days of thermal aging. However, after thirty days of aging, the cups sterilized with gamma irradiation in low-oxygen packaging wore several times faster than did the nonirradiated cups. Ion-implanting improved the wear resistance without thermal aging, but after extensive thermal aging the oxidation and wear were greater than those of the controls. Hylamer cups (that is, those that were sterilized with gas plasma) exhibited wear properties very close to those of the nonsterilized ultra-high molecular weight polyethylene cups (the controls) with or without aging. CONCLUSIONS: Sterilizing an ultra-high molecular weight polyethylene acetabular cup without radiation (for example, with ethylene oxide or gas plasma) avoids immediate and long-term oxidative degradation of the implant but does not improve the inherent wear resistance of the polyethylene. Sterilizing with use of gamma irradiation with the implant packaged in a low-oxygen atmosphere avoids immediate oxidation and cross-links the polyethylene, thereby increasing its wear resistance, but long-term oxidation of the residual free radicals may markedly reduce the wear resistance. Ideally, cross-linking with gamma irradiation to reduce wear should be done in a manner that avoids both immediate and long-term oxidation.     

How have new sterilization techniques and new forms of polyethylene influenced wear in total joint replacement?

Polyethylene has undergone many changes over the past several decades, including changes in consolidation processes, resin types, sterilization methods, packaging, and the extent of cross-linking. We believe that new sterilization techniques and forms of polyethylene have generally improved wear performance. Polyethylene sterilized without the use of radiation has been shown to have relatively high rates of wear in vivo. Ram-extruded polyethylene sterilized via gamma irradiation in air has been the most commonly used bearing material in the past several decades. Recently, components molded and gamma-sterilized without oxygen as well as highly cross-linked material have found increased clinical use. Exposure of polyethylene to radiation, either to sterilize it or to intentionally cross-link it, has been shown to improve the wear performance of the material. Newer second-generation methods of cross-linking polyethylene include the use of vitamin E, which quenches free radicals and demonstrates promise in providing low wear and desirable mechanical properties.     

Treatment of partial lacerations in flexor tendons by trimming. A biomechanical in vitro study

BACKGROUND: Treatment of a partial laceration in zone 2 of a flexor tendon is controversial. The intact part of the tendon can usually sustain forces of normal unresisted motion, and repaired partially lacerated tendons can actually be weaker than unrepaired ones. However, complications such as triggering or entrapment have been reported in association with unrepaired tendons. The purpose of this study was to measure the biomechanical behavior following trimming of the tendon as an alternative to repair. METHODS: Thirty-six flexor digitorum profundus tendons were harvested from sixteen unpaired fresh-frozen cadaveric human hands and were randomly assigned to be subjected to either 50% or 75% partial laceration, which was either lateral or volar, and were then assigned to no repair, repair with a running suture, or trimming. Mean and maximum gliding resistances were measured as the flexor digitorum profundus glided through the bone-A2 pulley complex and the flexor digitorum superficialis. Values were normalized to those measured in the intact tendon. The tendons were then distracted to failure, and maximum load and stiffness were recorded. RESULTS: There was triggering or entrapment of eight unrepaired tendons; two cases were severe, and six were minor. When no severe trigger was obvious, the unrepaired tendons had the lowest tendency for gliding resistance, followed by the tendons treated with trimming and then by those treated with the running suture. Overall, the tendons with a volar laceration had higher mean and maximum gliding resistance than those with a lateral laceration (p < 0.05), those with a 75% partial laceration had higher mean gliding resistance than those with a 50% laceration (p < 0.05), and the tendons that were repaired with running suture had higher mean gliding resistance than those treated with trimming (p < 0.05). Tendon strength was not significantly different among the three types of treatment. CONCLUSIONS: From the perspective of gliding resistance after partial tendon laceration, no repair appears necessary unless triggering is a problem. If triggering occurs, then trimming of a partially lacerated tendon may be a reliable alternative to repair, at least in terms of gliding resistance and strength.     

Nonsurgical treatment and early return to activity leads to improved Achilles tendon fatigue mechanics and functional outcomes during early healing in an animal model

Achilles tendon ruptures are common and devastating injuries; however, an optimized treatment and rehabilitation protocol has yet to be defined. Therefore, the objective of this study was to investigate the effects of surgical repair and return to activity on joint function and Achilles tendon properties after 3 weeks of healing. Sprague–Dawley rats (N = 100) received unilateral blunt transection of their Achilles tendon. Animals were then randomized into repaired or non‐repaired treatments, and further randomized into groups that returned to activity after 1 week (RTA1) or after 3 weeks (RTA3) of limb casting in plantarflexion. Limb function, passive joint mechanics, and tendon properties (mechanical, organizational using high frequency ultrasound, histological, and compositional) were evaluated. Results showed that both treatment and return to activity collectively affected limb function, passive joint mechanics, and tendon properties. Functionally, RTA1 animals had increased dorsiflexion ROM and weight bearing of the injured limb compared to RTA3 animals 3‐weeks post‐injury. Such functional improvements in RTA1 tendons were evidenced in their mechanical fatigue properties and increased cross sectional area compared to RTA3 tendons. When RTA1 was coupled with nonsurgical treatment, superior fatigue properties were achieved compared to repaired tendons. No differences in cell shape, cellularity, GAG, collagen type I, or TGF‐β staining were identified between groups, but collagen type III was elevated in RTA3 repaired tendons. The larger tissue area and increased fatigue resistance created in RTA1 tendons may prove critical for optimized outcomes in early Achilles tendon healing following complete rupture. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2172–2180, 2016.     

Long-term survival in men with high grade prostate cancer: a comparison between conservative treatment, radiation therapy and radical prostatectomy--a propensity scoring approach

PURPOSE: We performed a retrospective cohort study using propensity score analysis to calculate long-term survival in patients with prostate cancer with Gleason score 8 or greater who were treated with conservative therapy, radiation therapy and radical prostatectomy. MATERIALS AND METHODS: Between January 1, 1980 and December 31, 1997, 3,159 patients in the Henry Ford Health System were diagnosed with clinically localized prostate cancer. Of these patients 453 had a Gleason score of 8 or greater in the biopsy specimen and they were the cohort. The end points were overall and prostate cancer specific survival. Propensity score analysis was used to more precisely compare the 3 treatments of observation, radiation and radical prostatectomy. Median patient followup was longer in the radical prostatectomy arm than in the conservative treatment and radiation therapy arms (68 months vs 52 and 54, respectively). RESULTS: Of the 453 patients 197 (44%) were treated conservatively, 137 (30%) received radiation therapy and 119 (26%) underwent radical prostatectomy. Using propensity scoring analysis median overall survival for conservative therapy, radiation and radical prostatectomy was 5.2, 6.7 and 9.7 years, respectively. Median cancer specific survival was 7.8 years for conservative therapy and more than 14 years for radiation therapy and radical prostatectomy. The risk of cancer specific death following radical prostatectomy was 68% lower than for conservative treatment and 49% lower than for radiation therapy (p<0.001 and 0.053, respectively). CONCLUSIONS: Survival of men with high grade prostate cancer can be improved by radical prostatectomy or radiation therapy.     

Surface cross‐linked UHMWPE can enable the use of larger femoral heads in total joints

Limiting cross‐linking to the articular surfaces of ultrahigh molecular weight polyethylene (UHMWPE) to increase wear resistance while preventing detrimental effects of cross‐linking on mechanical strength has been a desirable goal. A surface cross‐linked UHMWPE can be achieved by blending UHMWPE with a free radical scavenger, such as vitamin E, consolidating the blend into an implant shape, extracting the vitamin E from the surface, and radiation cross‐linking the surface extracted blend. This process results in high cross‐link density in the vitamin E‐depleted surface region because vitamin E hinders cross‐linking during irradiation. In this study, we described the properties of successful extraction media and the manipulation of the wear and mechanical properties of extracted, irradiated blends. We showed that these formulations could have similar wear and significantly improved mechanical properties compared to currently available highly cross‐linked UHMWPEs. We believe that these materials can enable thinner implant forms and more anatomical designs in joint arthroplasty and may provide a feasible alternative to metal‐on‐metal implants. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:59–66, 2012     

How do material properties influence wear and fracture mechanisms?

The wear and fracture mechanisms of ultra-high-molecular-weight polyethylene (UHMWPE) hip and knee implant components are of great interest. The material properties of UHMWPE are affected by ionizing radiation as used for sterilization and cross-linking. Cross-linking with high-dose irradiation has been shown to improve the wear resistance of UHMWPE. However, cross-linking leads to a loss in properties such as ductility and resistance to fatigue crack propagation. Highly cross-linked UHMWPE may be more susceptible than conventional UHMWPE to fracture under severe clinical conditions (eg, impingement). Contemporary hip and knee simulator studies provide good information with which new UHMWPE formulations can be screened for clinical wear performance. However, comparable methodologies are lacking for screening UHMWPEs for fracture resistance. Mechanical tests as well as computational material and structural models should be developed to evaluate the combined effect of material and geometry (structure) on fracture resistance under clinically relevant loading conditions.     

The effect of near-infrared MLS laser radiation on cell membrane structure and radical generation

The therapeutic effects of low-power laser radiation of different wavelengths and light doses are well known, but the biochemical mechanism of the interaction of laser light with living cells is not fully understood. We have investigated the effect of MLS (Multiwave Locked System) laser near-infrared irradiation on cell membrane structure, functional properties, and free radical generation using human red blood cells and breast cancer MCF-4 cells. The cells were irradiated with low-intensity MLS near-infrared (simultaneously 808 nm, continuous emission and 905 nm, pulse emission, pulse-wave frequency, 1,000 or 2,000 Hz) laser light at light doses from 0 to 15 J (average power density 212.5 mW/cm², spot size was 3.18 cm²) at 22 °C, the activity membrane bound acetylcholinesterase, cell stability, anti-oxidative activity, and free radical generation were the parameters used in characterizing the structural and functional changes of the cell. Near-infrared low-intensity laser radiation changed the acetylcholinesterase activity of the red blood cell membrane in a dose-dependent manner: There was a considerable increase of maximal enzymatic rate and Michaelis constant due to changes in the membrane structure. Integral parameters such as erythrocyte stability, membrane lipid peroxidation, or methemoglobin levels remained unchanged. Anti-oxidative capacity of the red blood cells increased after MLS laser irradiation. This irradiation induced a time-dependent increase in free radical generation in MCF-4 cells. Low-intensity near-infrared MLS laser radiation induces free radical generation and changes enzymatic and anti-oxidative activities of cellular components. Free radical generation may be the mechanism of the biomodulative effect of laser radiation.     

Synergy of tendon stem cells and platelet-rich plasma in tendon healing

Injured rat Achilles tendons were treated with botulism toxin to create a mechanically unloaded condition (unloaded) or left untreated (loaded), and then treated with phosphate‐buffered saline (PBS), platelet‐rich plasma (PRP), tendon stem cells (TSCs), or a combination (TSCs + PRP). mRNA and protein expression of collagen I, collagen III, tenascin C, and Smad 8 were determined by real time PCR and immunostaining, respectively. Loaded tendons treated with PBS, PRP, or TSCs for 3 or 14 days had higher collagen I mRNA expression than unloaded tendons. Loaded tendons treated with PBS for 3 or 14 days or with PRP for 3 days had higher collagen I protein levels than unloaded tendons. Loaded tendons treated for 3 days with PBS, for 14 days with PRP or TSCs or TSCs + PRP for 3 or 14 days had higher collagen III protein levels than unloaded tendons. Collagen I mRNA levels were higher in TSCs + PRP‐treated loaded tendons compared to PBS‐treated loaded tendons on day 3 of treatment. Based on changes in the expression of tendon‐healing genes, our data suggest that the combination of TSCs and PRP has synergistic effects on tendon healing under both loaded and unloaded conditions, and loaded conditions improve tendon healing. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:991–997, 2012     

Treatment of recurrent craniopharyngioma

Treatment results on 48 patients with "recurrent" craniopharyngioma treated by surgery or/and radiation are analyzed. Median relapse-free survival time was 43.6 months in patients treated initially with radiation and 22.2 months without. Operative death occurred in 17% of all patients and in 3 out of six patients after total removal. The five- and ten-year survival rates were 91.7% and 66.8%, respectively, for 14 patients treated with combined surgery and radiation therapy. For 26 patients treated with surgery, the survival rates were 20.3% and 10.1%. All of 6 patients, who had received both initial and later radiotherapy, were well 1/2 to 18 years later without clinical evidence of radiation injury. These results lead us to the following conclusions: 1) A radical surgery in recurrent cases has the higher risks of mortality and morbidity than that of the first radical surgery. 2) Radiation therapy improved the survival rate of patients with "recurrent" craniopharyngioma. 3) After initial radiation therapy, additional irradiation was allowed based on the scale of nominal standard dosage and the estimation of "decay factor".