Late Tissue Response Research Articles

Proton- compared to X-irradiation leads to more acinar atrophy and greater hyposalivation accompanied by a differential cytokine response.

Proton therapy gives less dose to healthy tissue compared to conventional X-ray therapy, but systematic comparisons of normal tissue responses are lacking. The aim of this study was to investigate late tissue responses in the salivary glands following proton- or X-irradiation of the head and neck in mice. Moreover, we aimed at investigating molecular responses by monitoring the cytokine levels in serum and saliva. Female C57BL/6J mice underwent local fractionated irradiation with protons or X-rays to the maximally tolerated acute level. Saliva and serum were collected before and at different time points after irradiation to assess salivary gland function and cytokine expression. To study late responses in the major salivary glands, histological analyses were performed on tissues collected at day 105 after onset of irradiation. Saliva volume after proton and X-irradiation was significantly lower than for controls and remained reduced at all time points after irradiation. Protons caused reduced saliva production and fewer acinar cells in the submandibular glands compared to X-rays at day 105. X-rays induced a stronger inflammatory cytokine response in saliva compared to protons. This work supports previous preclinical findings and indicate that the relative biological effectiveness of protons in normal tissue might be higher than the commonly used value of 1.1.

Choice of Polymer, but Not Mesh Structure Variation, Reduces the Risk of Bacterial Infection with Staphylococcus aureus In Vivo.

Synthetic mesh material is of great importance for surgical incisional hernia repair. The physical and biochemical characteristics of the mesh influence mechanical stability and the foreign body tissue reaction. The influence on bacterial infections, however, remains ill-defined. The aim of the present study was to evaluate the influence of a modified mesh structure with variation in filament linking on the occurrence of bacterial infection that is indicated by the occurrence of CD68+, CD4+, and CD8+ cells in two different materials. A total of 56 male Sprague Dawley rats received a surgical mesh implant in a subcutaneous abdominal position. The mesh of two different polymers (polypropylene (PP) and polyvinylidenfluoride (PVDF)) and two different structures (standard structure and bold structure with higher filament linking) were compared. During the implantation, the meshes were infected with Staphylococcus (S.) aureus. After 7 and 21 days, meshes were explanted, and the early and late tissue responses to infection were histologically evaluated. Overall, the inflammatory tissue response was higher at 7 days when compared to 21 days. At 7 days, PP meshes of the standard structure (PP-S) showed the strongest inflammatory tissue response in comparison to all the other groups. At 21 days, no statistically significant difference between different meshes was detected. CD8+ cytotoxic T cells showed a significant difference at 21 days but not at 7 days. PP meshes of both structures showed a higher infiltration of CD8+ T cells than PVDF meshes. CD4+ T helper cells differed at 7 days but not at 21 days, and PVDF meshes in a bold structure showed the highest CD4+ T cell count. The number of CD68+ macrophages was also significantly higher in PP meshes in a standard structure when compared to PVDF meshes at 21 days. The inflammatory tissue response to S. aureus infection appears to be highest during the early period after mesh implantation. PP meshes showed a higher inflammatory response than PVDF meshes. The mesh material appears to be more important for the risk of infection than the variation in filament linking.

Ultra-hydrophilic stent platforms promote early vascular healing and minimise late tissue response: a potential alternative to second-generation drug-eluting stents

Simple surface modifications can enhance coronary stent performance. Ultra-hydrophilic surface (UHS) treatment of contemporary bare metal stents (BMS) was assessed in vivo to verify whether such stents can provide long-term efficacy comparable to second-generation drug-eluting stents (DES) while promoting healing comparably to BMS. UHS-treated BMS, untreated BMS and corresponding DES were tested for three commercial platforms. A thirty-day and a 90-day porcine coronary model were used to characterise late tissue response. Three-day porcine coronary and seven-day rabbit iliac models were used for early healing assessment. In porcine coronary arteries, hydrophilic treatment reduced intimal hyperplasia relative to the BMS and corresponding DES platforms (1.5-fold to threefold reduction in 30-day angiographic and histological stenosis; p<0.04). Endothelialisation was similar on UHS-treated BMS and untreated BMS, both in swine and rabbit models, and lower on DES. Elevation in thrombotic indices was infrequent (never observed with UHS, rare with BMS, most often with DES), but, when present, correlated with reduced endothelialisation (p<0.01). Ultra-hydrophilic surface treatment of contemporary stents conferred good healing while moderating neointimal and thrombotic responses. Such surfaces may offer safe alternatives to DES, particularly when rapid healing and short dual antiplatelet therapy (DAPT) are crucial.

CRT-704 Ultra-Hydrophilic Stents Promote Early Healing and Minimize Late Tissue Response: A Potential Alternative to Second-Generation Drug Eluting Stents

Clinical trials and meta-analyses demonstrate the low restenosis and stent thrombosis risks of next generation drug eluting stents (DES). Co-evolution of device, delivery technique, and drug-related factors all contribute, yet relative advantages are difficult to surmise. On a background of

Changes in mast cell number and stem cell factor expression in human skin after radiotherapy for breast cancer

Background and purposeMast cells are involved in the pathogenesis of radiation fibrosis and may be a therapeutic target. The mechanism of increased mast cell number in relation to acute and late tissue responses in human skin was investigated. Materials and methodsPunch biopsies of skin 1 and 15–18months after breast radiotherapy and a contralateral control biopsy were collected. Mast cells were quantified by immunohistochemistry using the markers c-Kit and tryptase. Stem cell factor (SCF) and collagen-1 expression was analysed by qRT-PCR. Clinical photographic scores were performed at post-surgical baseline and 18months and 5years post-radiotherapy. Primary human dermal microvascular endothelial cell (HDMEC) cultures were exposed to 2Gy ionising radiation and p53 and SCF expression was analysed by Western blotting and ELISA. ResultsDermal mast cell numbers were increased at 1 (p=0.047) and 18months (p=0.040) using c-Kit, and at 18months (p=0.024) using tryptase immunostaining. Collagen-1 mRNA in skin was increased at 1month (p=0.047) and 18months (p=0.032) and SCF mRNA increased at 1month (p=0.003). None of 16 cases scored had a change in photographic appearance at 5years, compared to baseline. SCF expression was not increased in HDMECs irradiated in vitro. ConclusionsIncreased mast cell number was associated with up-regulated collagen-1 expression in human skin at early and late time points. This increase could be secondary to elevated SCF expression at 1month after radiotherapy. Although mast cells accumulate around blood vessels, no endothelial cell secretion of SCF was seen after in vitro irradiation. Modification of mast cell number and collagen-1 expression may be observed in skin at 1 and 18months after radiotherapy in breast cancer patients with no change in photographic breast appearance at 5years.

A Case of Broncholithiasis Caused by Aspergillus with Broncho-Obstructive Pneumonia and Massive Hemoptysis

A broncholith is a calcified mediastinal lymph node, which partially or completely erodes into the bronchial lumen, and is related to the late tissue response to healing of granulomatous pulmonary infections, most commonly histoplasmosis or tuberculosis. However, there have been a few reports on broncholithiasis caused by Aspergillus. We experienced a case of broncholithiasis caused by Aspergillus, with broncho-obstructive pneumonia and massive hemoptysis. A 39 year-old woman was admitted to our hospital with right middle lobar pneumonia. On the fourth day following admission, massive hemoptysis developed, so an emergent bronchial artery embolization was performed. On the ninth day following admission, a broncholith on the lateral segmental bronchus of the right middle lobe was found by bronchoscopy, which was proved to be Aspergillus hypae with calcification on histological examination. After the simple bronchoscopic removal of the broncholith and empirical antibiotic therapy, the patient recovered without any complications.

Indicators of late normal tissue response after radiotherapy for head and neck cancer: fibroblasts, lymphocytes, genetics, DNA repair, and chromosome aberrations

Purpose: To investigate the relationship between late tissue response after radiotherapy, cellular sensitivity and DNA repair capacity measured in dermal fibroblasts and chromosomal aberrations measured in lymphocytes. The study was in particular designed to compare cellular parameters of patients with maximum differences in late tissue reactions. Materials and methods: The study was performed with 16 pair-wise matched head and neck cancer patients 2–7 years after curative therapy exhibiting maximum differences (grade 1 vs. grade 3) in late normal tissue reactions. Clinical endpoints were fibrosis, telangiectasia, mucositis and xerostomia using the radiation therapy oncology group score. Patients with grade 3 reactions were tested for mutations in ataxia telangiectasia (AT), Nijmegen Breakage Syndrome (NBS), MRE11, RAD50 and DNA ligase IV genes by means of polymerase chain reaction-single-strand conformation polymorphism and sequencing analysis. Skin fibroblasts obtained from biopsies were used to determine the cellular sensitivity by colony formation and the induction and repair of DNA double-strand breaks (dsb) using constant-field gel electrophoresis. Lymphocytes were taken to measure chromosomal damage either in metaphase using conventional chromosome analysis or in G 0 using premature chromosome condensation (PCC)-technique. Results: Patients with extreme late reactions (grade 3) showed no evidence for an AT, NBS, MRE11 or RAD50 mutation. Studies with fibroblasts revealed that extreme late reactions were associated neither with a pronounced cellular radiosensitivity nor with a difference in dsb repair capacity. In contrast, there was a significant difference in chromosomal damage measured in lymphocytes. After in vitro irradiation with 6 Gy, lymphocytes taken from overreacting patients showed on average a significantly higher number of lethal aberrations than lymphocytes isolated from patients with mild reactions (7.2±0.8 vs. 5.0±0.3). Similar differences were found for PCC fragments. Conclusion: This study suggests that lymphocytes are more promising than fibroblasts to predict patient's normal tissue response after radiotherapy.

Dose-response effects of 32P radioactive stents in an atherosclerotic porcine coronary model.

Experimental studies have demonstrated that 32P radioactive stents reduce neointimal formation at 28 days in porcine iliac and coronary arteries. Our objective was to determine the long-term dose-response effects of 1.0- to 12.0-microCi 32P radioactive stents in a porcine atherosclerotic coronary model. Control (n=19) and 1.0- to 12.0-microCi 32P radioactive (n=43) stents (total, n=62) were implanted in the coronary arteries of 31 miniature swine at 28 days after creation of a fibrocellular plaque by overstretch balloon injury and cholesterol feeding. Angiography and histomorphometry were performed at 6 months. Stent thrombosis occurred in 3 radioactive (7.7%) and no control stents (P=0.54). On histology, the mean neointimal area and the percent in-stent stenosis correlated positively with increasing stent activity (r=0.64, P<0.001). The mean neointimal area (mm2) for the stents with >/=3.0 microCi 32P (3.57+/-1.21) was significantly greater than that for the nonradioactive stents (1.78+/-0.68, P<0.0001). The neointima of the stents with >/=3.0 microCi 32P was composed of smooth muscle cells, matrix proteoglycans, calcification, foam cells, and cholesterol clefts. Continuous low-dose-rate irradiation delivered by high-activity (32)P radioactive stents promotes the formation of an "atheromatous" neointima after 6 months in this experimental model. These data may be useful for predicting late tissue responses to radioactive stents in human coronary arteries.

A Case of Broncholithiasis caused by Aspergillus

Broncholith is a calcified lymph node which partially or completely erodes into the bronchial lumen and broncholithiasis is a relatively rare condition which related to late tissue response to healing granulomatous pulmonary infections, most commonly histoplasmosis or tuberculosis. The prominent symptoms of broncholithiasis are coughing followed by hemoptysis and symptoms related to bronchial obstruction. The complications include bronchoesophageal fistula and aortotracheal fistula. We report one case of broncholithiasis caused by Aspergillus. The case was a 53 year-old house wife whose chief complaints were recurrent fever, chill and malaise. The chest film revealed an avoid hazziness on the right middle lobe and chest cr scan showed consolidation of lateral segment of right middle lobe with calcified small low attenuated lesion in right middle lobe bronchus. Aspergillosis confirmed by pathology after bronchoscopic removal of impacted Aspergillus containing muddy plug from lateral segmental branch of right middle lobe bronchus.

Poly( l-lactide) implants for repair of human orbital floor defects: Clinical and magnetic resonance imaging evaluation of long-term results

Purpose: The purpose of this study was to evaluate the long-term outcome of repair of orbital floor defects in patients with resorbable as-polymerized poly( l-lactide) (PLLA) implants and to determine whether these patients showed symptoms that could be indicative of the presence of a late tissue response. Patients and Methods: Six patients (four women, two men; mean age, 39 years; range, 18 to 67 years) treated with PLLA implants for orbital floor fractures were recalled for follow-up examination after a period ranging from 3 1 2 to 6 1 2 years. The examination consisted of an interview and a physical examination, including an ophthalmologic and orthoptic consultation. For evaluation of the orbital tissues, coronal spin echo T1- and T2-weighted magnetic resonance images (MRIs) were made through both orbits. Results: None of the patients reported any problems in the years preceding the follow-up examination that might have indicated complications. Clinical examination of the operative sites revealed no abnormalities. At ophthalmologic and orthoptic consultation, normal eye function, without diplopia or restriction of motility, was found in all patients. The MRIs showed no indication of an abnormal or increased soft tissue reaction in the orbital region. Conclusions: Based on the results of this study, it can be concluded that PLLA orbital floor implants have the potential for successful use in repair of human orbital floor defects.

1027 MRI-evaluation of late tissue response after radiosurgery in the rat brain

1027 MRI-evaluation of late tissue response after radiosurgery in the rat brain

Hyperfractionated, twice-a-day, radiotherapy may decrease IQ deterioration due to prophylactic cranial irradiation in childhood acute lymphoblastic leukemia: A radiobiological analysis

High cure rates in childhood acute lymphoblastic leukemia (ALL) are being achieved with aggressive systemic chemotherapy and treatment to sanctuary sites including prophylactic cranial irradiation. However, IQ deterioration is a dreaded complication of prophylactic cranial irradiation. IQ deterioration is a late sequela. Since there is evidence—both radiobiological and clinical—to suggest that acute tissue (including tumor) response and late tissue response can be separated by hyper-fractionation, we propose a twice-a-day radiotherapy in prophylactic cranial irradiation of childhood ALL to decrease delayed toxicity. Analysis based on current radiobiological models favors such a treatment scheme. However, only a prospective clinical trial can confirm whether IQ deterioration can be prevented or decreased with hyper-fractionated radiotherapy.

Radiobiological aspects of continuous low dose-rate irradiation and fractionated high dose-rate irradiation

The biological effects of continuous low dose-rate irradiation and fractionated high dose-rate irradiation in interstitial and intracavitary radiotherapy and total body irradiation are discussed in terms of dose-rate fractionation sensitivity for various tissues. A scaling between dose rate and fraction size was established for acute and late normal-tissue effects which can serve as a guideline for local treatment in the range of dose rates between 0.02 and 0.005 Gy/min and fraction sizes between 8.5 and 2.5 Gy. This is valid provided cell-cycle progression and proliferation can be ignored. Assuming that the acute and late tissue responses are characterised by α/β values of about 10 and 3 Gy and a mono-exponential repair half-time of about 3 h, the same total doses given with either of the two methods are approximately equivalent. The equivalence for acute and late non-hemopoietic normal tissue damage is 0.02 Gy/min and 8.5 Gy per fraction; 0.01 Gy/min and 5.5 Gy per fraction; and 0.005 Gy/min and 2.5 Gy per fraction. A very low dose rate, below 0.005 Gy/min, is thus necessary to simulate high dose-rate radiotherapy with fraction sizes of about 2 Gy. The scaling factor is, however, dependent on the repair half-time of the tissue. A review of published data on dose-rate effects for normal-tissue response showed a significantly stronger dose-rate dependence for late than for acute effects below 0.02 Gy/min. There was no significant difference in dose-rate dependence between various acute non-hemopoietic effects or between various late effects. The consistent dose-rate dependence, which justifies the use of a general scaling factor between fraction size and dose rate, contrasts with the wide range of values for repair half-time calculated for various normal-tissue effects. This indicates that the model currently used for repair kinetics is not satisfactory. There are also few experimental data in the clinical dose-rate range, below 0.02 Gy/min. It is therefore necessary to verify further the presented scaling between fraction size and dose rate.

Dose Fractionation Effects in Plateau-Phase Cultures of C3H 10T 1/2 Cells and Their Transformed Counterparts

A comparison of gamma-ray dose fractionation effects was made using plateau-phase cultures of C3H 10T1/2 cells and their transformed counterparts in an attempt to simulate basically similar populations of cells that differ primarily in their turnover rates. The status of cell populations with respect to their turnover rates may be an important factor influencing dose fractionation effects in early- and late-responding tissues. In this cell culture system, the rate of cell turnover was approximately three times higher for the plateau-phase transformed cultures. While the single acute dose survival curves for log-phase cells were indistinguishable, there were significant differences between the survival curves for plateau-phase cultures of the two cell types. These differences were qualitatively similar to the differences recently postulated for the survival of target cells governing early and late tissue responses. Both cell lines had a similar capacity for repair of sublethal damage, but untransformed cells had a much greater capacity to repair potentially lethal damage in plateau phase. Further, untransformed plateau-phase cultures were much more sensitive to a radiation-induced G1 (or G0 to G1) delay than transformed cultures. Multifraction survival curves were determined for both cell lines for doses per fraction ranging from 9.0 to 0.8 Gy, and from these isoeffect curves of log total dose versus dose per fraction were derived. The isoeffect curve for the slowly cycling, untransformed cells was found to be appreciably steeper than that for the more rapidly cycling transformed cells, a finding consistent with previously reported differences in dose fractionation isoeffect curves for early- and late-responding tissues in vivo.

Receptor occupancy vs. induction of Na+-K+-ATPase and Na+ transport by aldosterone.

In the urinary bladder of the toad Bufo marinus aldosterone (between 0.8 and 100 nM) stimulates Na+ transport [half-maximal induction concentration (K1/2) = 6.5 nM]. At low hormone concentrations (0.8-8 nM), the increase of Na+ transport between 0.75 and 2.5 h is accompanied by a fall in transepithelial resistance (R). Higher hormone concentrations (30-800 nM) induce an additional resistance-independent fraction of Na+ transport within 2.5-8 h. From 6 h on, aldosterone (between 0.2 and 20 nM) stimulates in the same tissue the biosynthesis rate of the alpha- and beta-subunits of Na+-K+-ATPase (K1/2 = 3 and 1.5 nM, respectively). New pump synthesis is thus not a prerequisite for the early mineralocorticoid response but might be linked to the late transport event. The mineralocorticoid response is usually ascribed to interaction with the higher affinity type 1 receptor. In the present study we show, however, that at least 55% of the overall Na+ transport response is linked to nuclear occupation of the lower affinity type 2 receptors [dissociation constant (Kd) = 50 nM, maximum number of binding sites (Nmax) = 315 fmol/mg protein]. Distinct aldosterone effects, such as the fall in R and the increase in Na+-K+-ATPase synthesis, are more closely related to occupation of type 1 receptors (Kd = 0.3 nM, Nmax = 23 fmol/mg protein). At maximal induction of these latter parameters, only about 20% of type 2 receptors are occupied. These results suggest that both types of aldosterone receptors are involved in the mediation of the full mineralocorticoid response: type 1 in the early and late and type 2 particularly in the late tissue response.