Bone Healing Following Irradiation During Tourniquet Ischaemia

The bone harvest chamber (BHC) methodology, a titanium implant for quantitative evaluations of bone healing, was used in order to investigate the radioprotective function of anoxia, in healing bone tissue. After incorporation of one BHC in each proximal tibial metaphysis of a rabbit it was possible to collect newly formed bone specimens in 3-week-periods without animal sacrifice. The amount of bone was determined by microradiography and densitometry. Ten animals divided into 2 groups were used. One group receiving a single dose of 25 Gy during tourniquet ischaemia was compared with another receiving the same dose during normal blood perfusion. A significantly improved bone healing response was seen in the ischaemic group, with a tendency to further improvement with increasing time after irradiation.     

Dose-response for bone regeneration after single doses of 60Co irradiation

The Bone Growth Chamber (BGC) methodology was used to establish a dose-response relationship for regeneration of mature bone tissue after irradiation of 5, 8, 11, 15 and 25 Gy single dose ⁶⁰Co. The BGC, which is a titanium implant, was inserted in the proximal tibial metaphyses, bilaterally, of a rabbit immediately following local irradiation to one tibia. Each animal thus served as its own control. During a healing period of 4 weeks, the two canals penetrating the implant became filled with more or less newly formed bone. At the end of the healing period, the implants were removed and taken apart and the newly formed bone was collected and its volume measured by microradiography and microdensitometry. It was found that in the dose range of 5 to 8 Gy bone regeneration was reduced by about 20% as compared to non-irradiated controls. Between 8 and 11 Gy, there was a critical range in that a small increase in dose resulted in a greatly reduced bone formation. At 11 Gy and above, the depression in bone formation, as compared to non-irradiated controls, was about 65 to 75%.     

A microradiographic investigation of cancellous bone healing after irradiation and hyperbaric oxygenation: a rabbit study

PURPOSE: To analyze the effect of irradiation on cancellous bone healing at different times after irradiation and to study if hyperbaric oxygen therapy (HBO) would affect the bone healing capacity, when delivered directly after irradiation. METHODS AND MATERIALS: Rabbits were given a single dose of 15 Gy (60)Co radiation to one hind leg, the other hind leg serving as control. A standardized defect through the femoral metaphysis of the rabbits was created by a trephine drill biopsy at different times after irradiation. New bone formation in the defect was evaluated by a new biopsy through the previous defect after a healing time of 8 weeks. The mineral contents of the biopsies were analyzed by microradiography and microdensitometry. RESULTS: There was a large variation in the bone-forming capacity expressed as bone mineral content between the animals. No statistically significant differences could be detected regarding the effect of irradiation, HBO, or delayed surgery. Qualitative histology revealed more pronounced inflammation, fibrosis, and bone resorption in the irradiated bone. CONCLUSIONS: No definite conclusions can be drawn from the results of this study, however it might be hypothesized that cancellous bone recovers faster than cortical bone from radiation trauma.     

Bone Cell Viability After Irradiation: An enzyme histochemical study

Adult rabbits were irradiated to one proximal tibial metaphysis while the contralateral tibia served as a control. Each animal was thus its own control. Single doses of 15, 25 and 40 Gy ⁶⁰Co were used. The follow-up time was 11 to 22 weeks after irradiation. A histochemical method, recording diaphorase (NADH₂ and NADPH₂) activity in osteocytes, was employed. This method is regarded as superior to conventional histology. No evidence of osteocyte death was found even after 22 weeks following 40 Gy irradiation. This is interpreted as an indication that the osteocytes, which are end stage cells, are relatively radioresistant.     

Dynamics of Irradiation Injury to Bone Tissue

The dynamic changes after a single dose of 15, 25 or 40 Gy ⁶⁰Co were followed in a titanium vital microscopic bone chamber which permitted observation of the same tissue compartment for over 2 years. The chamber consists of a hollow screw containing 2 glass rods 100 pm apart. The device was inserted into the cortex of the proximal tibial metaphysis of a rabbit. During a healing period of 4 to 6 weeks the space between the glass rods became filled with bone and vessels and in some cases fat. Once a steady state in bone remodelling had been achieved, the animals were irradiated. Vital microscopy was then performed at' regular intervals. Mature bone was relatively radioresistant since remodelling continued at a normal rate. In contrast, immature woven bone remained unlamellarized and in some animals tended to increase in amount. The vascular architecture was largely unaltered, even after 40 Gy. Thrombosis or hemorrhage clearly attributable to irradiation was not noted. Initially, the number of fat cells was reduced but repopulation was later seen in several cases.     

The density of mouse lung in vivo following X irradiation

The lungs of mice were irradiated with single X radiation doses of 5 to 14 Gy. Six weeks after irradiation, computed tomographic (CT) scans of the mice were performed at two-week intervals. Beyond 14 weeks after irradiation, the animals were scanned at 1-week intervals. The mice irradiated to 5 and 7 Gy exhibited no change in lung density, in comparison with the unirradiated lungs of control mice up to times of 48 weeks. The mice irradiated to doses of greater than 10 Gy exhibited marked increases in lung density at 15 weeks after irradiation. Increases in density followed a similar time course for these doses, but the magnitude of the density increase was dependent on the radiation dose. An interpretation of these findings in terms of radiation pneumonitis is presented, and the possibility of using Or to monitor lung density in radiotherapy patients is discussed.     

The treatment of solitary plasmacytoma of bone and extramedullary plasmacytoma

Eleven patients with solitary plasmacytoma of bone (SPB) and six patients with extramedullary plasmacytoma (EMP) were treated at the UCLA Center for the Health Sciences. Primary treatment in 14 of 17 patients was with radiation, while three patients were irradiated for recurrent disease. Eleven patients with SPB were irradiated with dose of 32-55 Gy, with 10 of 11 patients receiving doses of 40-55 Gy. Local control was achieved in 10 of 11 patients with SPB. One patient died with metastatic disease with unknown local status. Six patients with EMP were irradiated with doses of 38-56 Gy. Of these patients, two were locally controlled; one patient failed locally; one patient died during treatment; one patient died with local disease at 85 months after multiple resections, chemotherapy, and two courses of irradiation; and one patient was lost to follow-up. Progression to multiple myeloma was seen in 5 of 11 patients with SPB and in none of six patients with EMP. For patients with SPB, we recommend treating the entire bone to 40 Gy, with a boost when feasible. Patients with EMP receive the same dose, including the lymph nodes in tumors at high risk for spread. Radical surgical resections appear to be unwarranted.     

Rat Salivary Gland Function after Fractionated Irradiation

The aim of this study was to investigate longitudinal effects of fractionated irradiation, with various total doses, on salivary gland function in the rat. Female Sprague-Dawley rats were irradiated with 4, 5, 6, 7 or 8 Gy per day on five consecutive days. Irradiation was given to the head and neck region. Whole saliva was collected before and 2, 15 and 26 weeks after irradiation. In general the effects of irradiation on salivary gland function were found to be related to dose and time after exposure. Secretion rates were significantly decreased two weeks after irradiation with doses of 30 Gy or higher, after 15 weeks with 25 Gy or higher, and after 26 weeks with 20 Gy or higher. Response patterns to irradiation differed between the salivary constituents. Thus, the conclusions from this study are that early and late effects display different patterns and that the model used to study variations in salivary, gland function after fractionated irradiation must be adjusted to the question addressed.     

Radiation-induced changes in bone perfusion and angiogenesis

Purpose: To determine whether blood flow of bone is altered by limb irradiation and whether bFGF, an angiogenic cytokine, might alleviate any flow or growth abnormality resulting from 30 Gy single fraction irradiation.Methods and Materials: C3H mice received whole right hind limb radiation at doses of 0 to 30 Gy. Additional groups received 30 Gy, and then beginning 1 or 5 weeks later received intravenous bFGF at a dose of 6 μg/mouse, twice a week for 4 weeks. Serial X-ray films were taken to measure the tibias. At 33 weeks, laser Doppler flow (LDF) measurements were made of both limbs. Cytokine measurements were made using ELISA and RNase protection.Results: Bone growth was reduced following radiation in a dose dependent manner. bFGF improved bone growth after radiation even when begun 5 weeks after radiation, however, we detected no significant improvement in LDF of the irradiated bone or periosteum. Muscle tissue surrounding bone of the irradiated leg showed no increase in isoforms of TGFβ, TNF, or IFN. There was also no difference in the circulating plasma TGFβ1 in irradiated mice. In contrast, LDF increased significantly as a function of radiation dose in the nonirradiated tibia. Systemic delivery of bFGF appears to further enhance the increase in flow seen in the nonirradiated limb.Conclusion: Radiation induces a chronic antiangiogenic effect contributing to reduced limb growth. At 33 weeks the antiangiogenesis was not associated with local soft tissue elevations of TNF, IFN, or TGFβ. Radiation toxicity to bone is alleviated by bFGF therapy suggesting that powerful locally-acting antiangiogenic mechanisms are involved. We postulate that the increased LDF of the contralateral tibia is due to circulating angiogenesis factors that are elevated to compensate for the radiation-induced antiangiogenesis.     

Bone necrosis and tumor induction following experimental intraoperative irradiation

The bone of the lumbar vertebrae of 153 dogs was examined 2 and 5 years after intraoperative irradiation (IORT), fractionated external beam irradiation (EBRT), or the combination. Groups of dogs received 15 to 55 Gy IORT only, 10 to 47.5 Gy IORT combined with 50 Gy EBRT in 2 Gy fractions or 60 to 80 Gy EBRT in 30 fractions. Six MeV electrons were used for IORT, and EBRT was done using photons from a 6 MV linear accelerator. The paraaortic region was irradiated and the ventral part of the lumbar vertebrae was in the 90% isodose level. Two years after irradiation, the dose causing significant bone necrosis as determined by at least 50% empty lacunae in the vertebral cortex was 38.2 Gy IORT alone and 32.5 Gy IORT combined with EBRT. Five years after irradiation, the dose causing 50% empty lacunae was 28.5 Gy IORT only and 14.4 Gy IORT combined with EBRT. The ED50 for lesions of the ventral vertebral artery was 21.7 Gy IORT only and 20.1 Gy IORT combined with 50 Gy EBRT 2 years after irradiation and 27.0 Gy IORT only and 20.0 Gy IORT combined with 50 Gy EBRT 5 years after irradiation. All lesions after EBRT only were mild. Eight dogs developed osteosarcomas 4 to 5 years after irradiation, one at 47.5 Gy IORT only and the remainder at 25.0 Gy IORT and above combined with 50 Gy EBRT. In conclusion, the extent of empty lacunae, indicating bone necrosis, was more severe 5 years after irradiation than after 2 years. The effect of 50 Gy EBRT in 2 Gy fractions was equivalent to about 6 Gy IORT 2 years after irradiation and to about 14 Gy 5 years after irradiation. Based on these estimates, IORT doses of 10 to 15 Gy have an effect 5 times or greater than the amount given in 2 Gy fractions. Osteosarcomas occurred in 21% of dogs which received doses greater than 25 Gy IORT. Doses of 15 to 20 Gy IORT in combination with 50 Gy EBRT in 2 Gy fractions may be near the tolerance level for late developing bone injury.     

放射性骨损伤愈合能力降低机制的实验研究

 目的　探讨放射性骨损伤 (RBI)愈合能力降低的机制。方法　6 0 Coγ射线 15Gy单次照射并致兔右胫骨骨折 ,以半环槽氏外固定器固定 ,未照射组为对照组。术后 3d、1、3、6、12、2 4周通过组织学、血流量测定及免疫组化 (BMP与TGF β1)观察骨折愈合情况。结果　实验组骨折愈合较对照组晚 12～ 16周 ,且骨折端血流量明显降低 ;BMP与TGF β1的表达亦低于对照组。结论　RBI愈合能力下降的原因是骨组织血运障碍与抑制BMP与TGF \| β1的综合作用。     

Results of radiotherapeutic management of primary carcinoma of the vagina

Forty-five previously untreated patients with primary carcinoma of the vagina were treated with curative radiotherapy from 1965 through 1985. All patients were staged according to the FIGO system. One patient was classified as Stage 0, 15 as Stage I, 22 as Stage II, 6 as Stage III, and 1 as Stage IV. Treatment consisted of intracavitary irradiation alone in Stage 0 patients. Stage I patients received intracavitary/interstitial irradiation alone or in combination with external irradiation and an implant when feasible. When treated with an implant only, the total tumor dose delivered was between 65-70 Gy. External irradiation consisted of delivering a dose of 45-50 Gy over a period of 4 1/2-5 weeks to the whole pelvis to treat the regional lymph nodes. An additional dose of 20-25 Gy was delivered to the site of original involvement using an implant when feasible. If not technically feasible, as in advanced stages, the patient was treated with additional external irradiation to a total dose of 65-70 Gy by a shrinking field technique. All patients except one were followed either until death or for a minimum of 2 years. The actuarial 5-year survival rates were 100% for Stage 0, 78% for Stage I, and 71% for Stage II patients. None of the patients with Stage III or IV disease survived. Of the patients who recurred, all but two did so within 16 months after diagnosis. Pelvic recurrence as the first site of recurrence occurred in 86% of the patients who recurred. Distant recurrence as a component occurred in 20% of all failures. Complications as a consequence of therapy occurred in 18% of the patients. Vaginal necrosis that healed with conservative treatment was seen in four patients and the other four patients had rectal complications of varying severity. Thus, curative radiotherapy is an effective method of treatment, with acceptable morbidity, in patients with early stage primary carcinoma of the vagina.     

The problem of restoring bone marrow, irradiated during radiotherapy of Hodgkin's disease patients]

The results of bone marrow (BM) visualisation of 663 irradiated regions were analysed. In all cases BM absorbed doses varied between 10-40 Gy. Active accumulation of 99mTc-colloids was observed in 48 out of 60 regions irradiated within 20 Gy. This pattern proved the possibility of effective and rapid hematopoietic regeneration after low-dose radiotherapy. On the contrary, during the first 6 months after BM irradiation with doses over 25 Gy we detected prominent depression of tracer uptake in 86.2% of all regions. It was shown that intensity of BM regeneration reached its peak during the second half-year after irradiation within 25-40 Gy. BM recovery during this period was dose dependent and was detected in 47.7% areas irradiated with 30 Gy and 24.7%--with 40 Gy. Regression analysis revealed significant correlation of postradiotherapy hematopoietic status with the value of BM absorbed dose and the time after the end of radiotherapy. Scintigraphic patterns of BM regeneration were registered in 69 of 89 (77.5%) regions irradiated within 25-30 Gy and only in 96 out of 231 (41.6%)--within 35-40 Gy.     

猪下丘脑不同剂量照射后神经内分泌反应

目的　观察幼年猪下丘脑区接受不同剂量单次照射后下丘脑—垂体—睾丸轴反应。方法　(1)20 只幼年雄性小型猪分为5 个组,每组4 只,以蝶鞍上1 cm 为靶点等中心、10 MV 的X 射线、=16 m m 限光筒平行对穿照射,靶区中心吸收剂量分别为5 ,10,15 ,20 Gy;(2) 猪血清睾丸酮测定:照射后每隔4 周采血1 次直至照射后36 周,采用放射免疫分析方法测定猪血清睾丸酮水平;(3)将观察期满40 周的动物处死,取下丘脑组织行电镜和光镜观察,睾丸组织行光镜观察。结果　(1)照射后20 周,15,20 Gy 组动物体重出现降低趋势。(2)5 Gy 组血清睾丸酮水平在照射后曾有一过性降低,于照射后28 周与对照组基本相似;10 Gy 组略低于对照组;15,20 Gy 组持续呈低水平。(3) 光镜观察见下丘脑组织基本正常;电镜观察见10,15 ,20 Gy 组神经细胞浆水肿,髓鞘肿胀、内膜向轴索内突出,血管内皮细胞和胶质细胞增生;光镜下见精原细胞和间质细胞数量减少,细胞体积明显缩小,以20 Gy 组为最明显。结论　幼年猪下丘脑区接受5 Gy 的单次剂量照射就可以发生促性腺激素释放素神经细胞分泌功能的抑制,认为幼年猪的下丘脑区属放射敏感组织;10 Gy 以上单次照射可以导致明显神经内分泌障碍     

Effect of radiation on the expression of E-cadherin and α-catenin and invasive capacity in human lung cancer cell line in vitro

Purpose: To investigate the effect of radiation on E-cadherin and α-catenin expression in a human lung cancer cell line, and also evaluate invasive capacity in the membrane invasion culture system using the Boyden Chamber.Materials and Methods: The immunoblot and immunofluorescence analyses were performed using the human lung cancer cell line A549 to examine altered expression of E-cadherin and α-catenin after irradiation. We also compared invasive capacity of untreated cells with that of irradiated cells.Results: Immunoblot analysis revealed that the expression of E-cadherin increased after irradiation. In a time-course analysis, the expression was increased 6 h after irradiation with 10 Gy and reached its peak level at 24 h, being 2.3 times the control value, whereas expression at 1 and 3 h after irradiation was almost equivalent to that of the control. A slight increase in expression was observed after irradiation of 2 Gy and the expression reached peak levels after 5 Gy. After fractionated irradiation, the increase in expression of both E-cadherin and α-catenin was observed, and the alteration of α-catenin was more prominent than that after a single irradiation of the same total dose. In the immunofluorescence study for E-cadherin antibody analyzed by confocal laser scanning microscopy, increased intensity in irradiated cells produced as a nondisrupted and continuous line at cell–cell contact sites. In an invasive assay, the number of migrated cells in irradiated cells after a dose of 5 and 10 Gy was reduced significantly compared to untreated cells.Conclusion: The results indicate that irradiation of A549 increased the expression of E-cadherin, possibly preserving their functional property.     

Optimum dose range for the amelioration of long term radiation-induced hyposalivation using prophylactic pilocarpine treatment.

BACKGROUND: To determine dose and time dependency of pilocarpine pre-treatment protection from late damage after unilateral irradiation of the rat parotid gland. METHODS AND MATERIALS: The right parotid gland of saline (1mg/ml) or pilocarpine (4 mg/kg) pre-treated rats was irradiated with 10, 15 and 20 Gy. Saliva was collected from the irradiated and shielded parotid before, 30, 60, 120 and 240 days after irradiation. The number of acinar cells/gland was determined 30, 120 and 240 days after irradiation by histological examination. RESULTS: Pilocarpine pre-treated rats, protection of parotid gland function was seen in the early-intermediate phase (0-120 days) after 15 Gy and in the late phase (>120 days) after 10 and 15 Gy. Although no protection was observed after 20 Gy, a stimulatory effect of pilocarpine on the non-irradiated gland resulted in a significant increase in total saliva secretion. The increase in function after pilocarpine treatment was paralleled by a significant increase in the number of acinar cells in both the irradiated and shielded glands. CONCLUSIONS: Pre-irradiation treatment with pilocarpine induces compensatory response, at lower doses, in the irradiated and at higher doses in the non-irradiated gland reducing late damage, due to stimulation of unirradiated or surviving cells to divide.     

Cochlear implants: response to therapeutic irradiation

PURPOSE: To determine the response of cochlear implants ("bionic ears") to therapeutic irradiation. METHODS AND MATERIALS: A patient with a cochlear implant was referred for palliative cranial irradiation. As there were no published or manufacturer's data available regarding the response to radiation, implants were tested for functional changes following irradiation. Cochlear implants were supplied by Cochlear Ltd. Two units each of models CI22M, CI22M (with the second generation integrated circuit) and CI24M were irradiated with 4 MV X-rays, and an unirradiated unit of each model was used as a control. The implants were irradiated initially with 25 daily fractions to 50 Gy. To determine the response at higher doses, 10 Gy fractions were delivered to the same implants to 100 Gy, followed by a final fraction of 50 Gy (total dose 150 Gy). The implants were tested after each 10 Gy, up to 1100 Gy, and at 150 Gy. Several indicators of functionality were assessed, including RF (radio frequency) link range, and stimulator output current. The radiation shielding effect of the implants was also assessed. RESULTS: Within the dose range < or = 50 Gy, the stimulator output current of the CI22M units was the only parameter to change. At higher doses (to 150 Gy), changes in current output continued, and gradual loss of RF link range occurred in the CI22M units. The CI24M units showed changes in output current to 100 Gy, and large changes at 150 Gy. Dose attenuation by the implants was measured at 6% for ipsilateral single field 4 MV X-rays. CONCLUSION: Our results suggest that patients with these cochlear implants can receive cranial irradiation with a low risk of implant failure. Changes in stimulator output current can be compensated simply by reprogramming the speech map after the course of radiation treatment.     

Late effects of intraoperative radiation therapy in anastomotic rat colon

Purpose: to determine whether intraoperative radiotherapy causes long-term negative effects on the healing of colonic anastomoses in the rat.Methods and Materials: 175 rats were divided into seven equal groups. One group served as sham-irradiated control group. In the others, following a colonic resection, 1 or 2 cm of the distal bowel limb was irradiated with a single dose of 10, 15, or 20 Gy (groups 10/1, 15/1, 20/1, 10/2, 15/2, and 20/2, respectively). Subsequently, an anastomosis was constructed. The animals were killed after 6 (n = 10 in each group) or 12 (n = 15) months. The abdomen was inspected for abnormalities and the colonic diameter was measured. The anastomotic segment was analyzed biochemically (hydroxyproline) and histologically.Results: During the experimental period, 1 rat (group 15/1) died because of anastomotic leakage and 3 others died from unknown causes. There was no difference in colonic diameter between groups. Altogether 17 rats developed an adenocarcinoma in the irradiated area: 11 of these had received a dose of 20 Gy. Histological observation indicated that fibrosis was present only in a limited number of animals, mostly after irradiation with a dose of 15 or 20 Gy. All anastomoses were functional and showed normal histology. The hydroxyproline content of the anastomotic segment was increased—with respect to the control group—only in the 20/2 group after 6 months. After 12 months, the hydroxyproline concentration in the (irradiated) segment distal to the anastomosis proper was higher in the 10/1 and 15/1 groups than in the control group. Otherwise, there were no differences between groups.Conclusion: Intraoperative irradiation with a single dose of 10–20 Gy, delivered to the distal limb used for anastomotic construction, does not appear to constitute a threat to anastomotic integrity. Dose-related changes included formation of adenocarcinomas and fibrosis, but function and histology of the anastomosis proper remained unaffected.     

Radiation tolerance and fractionation sensitivity of the developing rat cervical spinal cord.

To investigate the influence of age at irradiation on single dose radiation tolerance and fractionation sensitivity, the cervical spinal cord of rats was irradiated at the age of 1 week and at 15-18 weeks (adult). While the main histological lesions seem to be comparable after irradiation at the two ages, differences were found in single dose tolerance, latency to paresis due to white matter lesions, and fractionation sensitivity. The 50% effect dose (ED50) for single dose irradiation at one week was 19.5 Gy, which is only 10%, but significantly (p < 0.05), lower than the ED50 of about 21.5 Gy at 3 weeks and above. The latency to paresis was clearly influenced by the age at irradiation. The latency in the rats irradiated at 1 week was about 2 weeks, while for adult rats a latency of about 8 months was observed. The fractionation sensitivity for irradiation at 1 week was lower than the fractionation sensitivity of the adult rats; the alpha/beta value at 1 week was estimated to be 4.5 Gy, while for the adult rats an alpha/beta value of 1.8 Gy was found. As a consequence, the observed small difference in tolerance to single doses between 1 week-old and adult rats is further enhanced after fractionated irradiation. During prolonged irradiation treatments this decreased tolerance may be compensated by a higher proliferation rate in the immature central nervous system. The results of the present experiments indicate that, for a single tissue and endpoint, paresis due to white matter lesions in the rat cervical spinal cord, the latency to expression of damage and the fractionation sensitivity clearly change with age at irradiation.