Evaluation of Deoxyribonucleic Acid Damage Using Neutral Comet Assay for High Radiation Doses: A Feasibility Study.

Purpose: This study aims to investigate the use of the neutral comet assay to assess deoxyribonucleic acid (DNA) damage in lymphocytes exposed to high doses of radiation. Materials and Methods: The research was conducted by obtaining informed consent, after which blood samples were taken from seven healthy individuals and this study was approved by the institutional ethics committee. At first, for the determination of dose-effect curves, samples obtained from the first five individuals were irradiated for doses ranging from 0 to 35 Gy after which they were processed under neutral comet assay. In order to verify the determined dose-effect curves, a test dose of 15 Gy was delivered to the samples obtained from the sixth and seventh individuals. The amount of DNA damage from the obtained comet assay images was analyzed using four comet assay parameters namely % tail DNA, tail length, tail moment (TM), and Olive TM (OTM). The most suitable comet assay parameter was evaluated based on the obtained dose-effect curves. Furthermore, the distribution of individual cells for each dose point was evaluated for all the four comet assay parameters to find the optimal parameter. Results: From our results, it was found that from 0 to 25 Gy all the four comet assay parameters fit well into a linear quadratic curve and above 25 Gy saturation was observed. Based on the individual cell distribution data, it was found that % tail DNA could be an optimal choice to evaluate DNA damage while using neutral comet assay for high-dose ionizing radiation. Conclusion: The neutral comet assay could be a potential tool to assess DNA damage from high doses of ionizing radiation greater than 5 Gy.

Fricke xylenol glycine gel dosimeter for in vivo dosimetry at extended treatment distance.

Fricke xylenol gelatin with glycine (FXGGly) as gel dosimeter was investigated for in vivo dosimetry at extended source-to-surface distance (eSSD) and validated with optically stimulated luminescence dosimeters (OSLD). FXGGly dosimeter was calibrated with a low dose rate of 10 cGy/min at eSSD and evaluated using anthropomorphic phantom simulating the actual treatment scenario. The FXGGly dosimeter was demonstrated as a suitable in vivo dosimeter for total body irradiation at eSSD with desirable dosimetric accuracy (±â€¯2%) in comparison with OSLD or ionization chamber.

Extended localization and adaptive dose calculation using HU corrected cone beam CT: Phantom study.

BACKGROUND AND AIM: The practicability of computing dose calculation on cone beam CT (CBCT) has been widely investigated. In most clinical scenarios, the craniocaudal scanning length of CBCT is found to be inadequate for localization. This study aims to explore extended tomographic localization and adaptive dose calculation strategies using Hounsfield unit (HU) corrected CBCT image sets. MATERIALS AND METHODS: Planning CT (pCT) images of the Rando phantom (T12-to-midthigh) were acquired with pelvic-protocol using Biograph CT-scanner. Similarly, half-fan CBCT were acquired with fixed parameters using Clinac2100C/D linear accelerator integrated with an on-board imager with 2-longitudinal positions of the table. For extended localization and dose calculation, two stitching strategies viz., one with "penumbral-overlap" (S1) and the other with "no-overlap" (S2) and a local HU-correction technique were performed using custom-developed MATLAB scripts. Fluence modulated treatment plans computed on pCT were mapped with stitched CBCT and the dosimetric analyses such as dose-profile comparison, 3D-gamma (γ) evaluation and dose-volume histogram (DVH) comparison were performed. RESULTS: Localizing scanning length of CBCT was extended by up to 15 cm and 16 cm in S1 and S2 strategies, respectively. Treatment plan mapping resulted in minor variations in the volumes of delineated structures and the beam centre co-ordinates. While the former showed maximum variations of -1.4% and -1.6%, the latter showed maximum of 1.4 mm and 2.7 mm differences in anteroposterior direction in S1 and S2 protocols, respectively. Dosimetric evaluations viz., dose profile and DVH comparisons were found to be in agreement with one another. In addition, γ-evaluation results showed superior pass-rates (≥98.5%) for both 3%/3 mm dose-difference (DD) and distance-to-agreement (DTA) and 2%/2 mm DD/DTA criteria with desirable dosimetric accuracy. CONCLUSION: Cone beam tomographic stitching and local HU-correction strategies developed to facilitate extended localization and dose calculation enables routine adaptive re-planning while circumventing the need for repeated pCT.

A Hybrid Conformal Planning Technique with Solitary Dynamic Portal for Postmastectomy Radiotherapy with Regional Nodes.

PURPOSE: This study focuses on incorporation of a solitary dynamic portal (SDP) in conformal planning for postmastectomy radiotherapy (PMRT) with nodal regions with an intention to overcome the treatment planning limitations imposed by conventional techniques. MATERIALS AND METHODS: Twenty-four patients who underwent surgical mastectomy followed by PMRT were included in this study. Initially, a treatment plan comprising tangential beams fitted to beam's-eye-view (BEV) of chest wall (CW) and a direct anterior field fitted to BEV of nodal region, both sharing a single isocenter was generated using Eclipse treatment planning system. Multiple field-in-fields with optimum beam weights (5% per field) were added primarily from the medial tangent, fitted to BEV of entire target volume, and finally converted into a dynamic portal. Dosimetric analysis for the treatment plans and fluence verification for the dynamic portals were performed. RESULTS AND DISCUSSION: Conformal plans with SDP showed excellent dose coverage (V95%>95%), higher degree of tumor dose conformity (≤1.25) and homogeneity (≤0.12) without compromising the organ at risk sparing for PMRT with nodal region. Treatment plans with SDP considerably reduced the lower isodose spread to the ipsilateral lung, heart, and healthy tissue without affecting the dose homogeneity. Further, gamma evaluation showed more than 96% pixel pass rate for standard 3%/3 mm dose difference and distance-to-agreement criteria. Moreover, this plan offers less probability of "geometrical miss" at the highly irregular CW with regional nodal radiotherapy. CONCLUSION: Hybrid conformal plans with SDP would facilitate improved dose distribution and reduced uncertainty in delivery and promises to be a suitable treatment option for complex postmastectomy CW with regional nodal irradiation.

Evaluating healing for cancer in a community setting from the perspective of clients and healers: a pilot study.

The real-life practice of 'healing' for cancer in the community as perceived by clients and healers was investigated in a multi-method pilot study. Fifteen clients received six weekly healing sessions. Pre- and post-changes in perception towards well-being and client experience were assessed by EuroQol (EQ-5D), measure yourself concerns and well-being (MYCaW) and a client satisfaction tool. Qualitative methods, including focus groups, explored the perceived effects of healing in more depth and the participants' experience of taking part in research. The study was not designed to test the effect of healing on disease. Quantitative data showed perceived significant improvements in 'concerns/problems' for which clients wanted help (p<0.01), well-being (p<0.01) and anxiety/depression (p<0.05) over the course of healing. Significant effects were not seen in all areas of quality of life. Qualitative analysis showed clients mainly sought help for psychological and emotional concerns and reported only beneficial effects of healing. Clients attributed many of the quantitative improvements to healing itself. Despite some concerns, healers and clients engaged fully with the research process, and were enthusiastic about the importance of research into healing. Our study suggests that, while there are some confounding issues and study limitations to address, clients and healers perceive healing to have a range of benefits, particularly in terms of coping with cancer, and regard it as a useful approach that can be applied in a community setting alongside conventional medicine.

Optimization and audit of radiation dose during percutaneous transluminal coronary angioplasty.

The percutaneous transluminal coronary angioplasty (PTCA) is one of the interventional procedures which impart high radiation doses to patients compared to the other cardiologic procedures. This study intends to audit and optimize radiation dose imparted to patients undergoing PTCA. Forty-four patients who underwent PTCA involving single or multiple stent placement guided under cardiovascular X-ray machine were included in the study. Radiation doses were measured using dose area product (DAP) meter for patients undergoing single and multiple stent placements during PTCA. A dose reduction of 27-47% was achieved using copper filters and optimal exposure parameters. The mean DAP values before optimization were 66.16 and 122.68 Gy cm(2) for single and multiple stent placement respectively. These values were 48.67 and 65.44 Gy cm(2) respectively after optimization. In the present scenario, due to the increase in the number of PTCAs performed and the associated risk from radiation, periodical audit of radiation doses for interventional procedures are recommended.

Audit of radiation dose during balloon mitral valvuloplasty procedure.

Radiation doses to patients during cardiological procedures are of concern in the present day scenario. This study was intended to audit the radiation dose imparted to patients during the balloon mitral valvuloplasty (BMV) procedure. Thirty seven patients who underwent the BMV procedure performed using two dedicated cardiovascular machines were included in the study. The radiation doses imparted to patients were measured using a dose area product (DAP) meter. The mean DAP value for patients who underwent the BMV procedure from one machine was 19.16 Gy cm(2) and from the other was 21.19 Gy cm(2). Optimisation of exposure parameters and radiation doses was possible for one machine with the use of appropriate copper filters and optimised exposure parameters, and the mean DAP value after optimisation was 9.36 Gy cm(2).

Point mutations and overexpression of Ron induce transformation, tumor formation, and metastasis.

The receptor tyrosine kinase Ron is a member of the receptor family that includes the proto-oncogene Met and the avian oncogene Sea. The interaction of Ron with its ligand, known as hepatocyte growth factor-like protein (HGFL) or macrophage stimulating protein (MSP), induces crucial cellular responses including invasive growth, proliferation, cell scattering, and branching morphogenesis. Based on the homology and functional similarities between Met and Ron it was hypothesized that Ron may be important in tumor formation and metastasis. To test this hypothesis, wild-type mouse Ron and three mutant forms of Ron containing mutations similar to those found in the Met gene in human hereditary papillary renal carcinoma (HPRC), were expressed in NIH3T3 cells. A transformed phenotype was produced in cell lines expressing either wild-type Ron or the mutated Ron proteins. Further, these cell lines displayed oncogenic potential by exhibiting increased proliferation and constitutive phosphorylation of Ron. These cell lines were also tested for the ability to form solid tumors. Cells expressing wild-type Ron and the three proteins with single amino acid substitutions were highly tumorigenic in vivo. In a model of experimental metastasis, two of the cell lines with altered Ron protein formed highly aggressive tumors in the lungs. These results suggest that Ron may be an aggressive oncogene when either overexpressed or when activated by mutation.

Ron-mediated cytoplasmic signaling is dispensable for viability but is required to limit inflammatory responses.

Ron receptor activation induces numerous cellular responses in vitro, including proliferation, dissociation, and migration. Ron is thought to be involved in blood cell development in vivo, as well as in many aspects of the immune response including macrophage activation, antigen presentation, and nitric oxide regulation. In previous studies to determine the function of Ron in vivo, mice were generated with a targeted deletion of the extracellular and transmembrane regions of this gene. Mice homologous for this deletion appear to die early during embryonic development. To ascertain the in vivo function of Ron in more detail, we have generated mice with a germline ablation of the tyrosine kinase domain. Strikingly, our studies indicate that this domain of Ron, and therefore Ron cytoplasmic signaling, is not essential for embryonic development. While mice deficient in this domain are overtly normal, mice lacking Ron signaling have an altered ability to regulate nitric oxide levels and, in addition, have enhanced tissue damage following acute and cell-mediated inflammatory responses.

A case of elevated spontaneous micronucleus frequency derived from chromosome 2.

This work tested the hypothesis that the content of spontaneous micronuclei in lymphocytes in an apparently healthy normal human subject, who exhibited an unusually high micronucleus frequency, was non-random. Several DNA probes were used in fluorescent in-situ hybridization (FISH), beginning with a probe generated from the subject's micronuclei. Micronuclei obtained from peripheral blood lymphocytes by microdissection were subjected to random amplification of polymorphic DNA (RAPD-PCR), and a unique PCR product was then used to isolate a cosmid clone from a human genomic library. This clone hybridized to chromosome 2. Subsequently, commercial probes were included in FISH analyses of micronuclei from the subject and age- and sex-matched controls. No significant differences were found between subject and controls in the percentages of micronuclei hybridizing with a centromere probe for the X chromosome or a painting probe for chromosome 3. However, the subject had a very highly significant increase (p<0.0001) in chromosome 2 in micronuclei over a level that might be expected to be present by chance. Characterization of micronuclei may be a promising tool in studies of mechanisms of inherited or induced chromosome instability. The strength of the strategy employed in this study is that, by characterizing the chromosomes present in micronuclei, this work has advanced from an observation of chromosomal instability to a foundation for study of the mechanism underlying the observation.

Spontaneous micronucleus frequency and age: what are normal values?

Micronucleus frequency in epidemiological studies of human exposure has become a preferred biomarker. A generally recognized observation is that micronucleus frequency increases with age. One requirement for comparison of data, which is being generated in many countries, is some common agreement about what constitutes a typical or normal background frequency of micronuclei. This is also a requirement when examining any individual value, especially one which might be considered an outlier. A mean value for normal micronucleus frequency with age is developed via the analysis of multiple studies, all of which employed large population bases and generally were conducted with the intent of determining population values. The result is presented here, with the understanding that it may over- or under-estimate the actual values in certain populations.

Patient characteristics, methods of diagnosis and treatment of melanoma in the United States.

The American College of Surgeons performed a patient care and evaluation study of melanoma for 1981 and 1987 to determine the presenting symptoms, methods of evaluation, clinical management and resulting outcome. Melanomas of the skin, eye, mucous membrane, metastases with unknown primary site and miscellaneous sites were included. Details concerning 5,004 patients from 681 hospitals in the study in 1981 and 6,900 patients from 844 hospitals in the study in 1987 were obtained--most melanomas were located in the skin; a decline in symptoms occurred at initial diagnosis; an increase in age at first diagnosis was reported; most melanomas were in Caucasian patients; slightly more melanomas occurred in men than women; more melanomas occurred in men on the head and neck and trunk, and more in the lower extremity in women; most tumors were not large in diameter; a significant shift was reported to lower levels of Clark's invasion, and a significant amount of unknowns existed in the Breslow's thickness of invasion. The large number of unknowns makes analysis difficult, but there seems to be some shift toward thinner levels of Breslow's in tumors in which it was known, from 1981 to 1987. Only a small proportion of patients in the current series was known to have node involvement or known distant metastases. An overall decline in diagnostic studies occurred between 1981 and 1987.

National survey of patterns of care for brain-tumor patients.

An excellent response by participating institutions was realized in this survey of patterns of care for patients with primary brain tumors. Since the histopathology of the tumor is such a strong predictor of outcome and influences care so greatly, most analyses were performed not only on the overall series of patients but also by World Health Organization histological classification. Several factors that influence outcome were identified: tumor type, patient age, patient Karnofsky rating, tumor location, and therapy. Very few cases were coded as regards the American Joint Committee on Cancer clinical stage, and few potentially eligible cases were placed in investigative protocols. It behooves those centers providing investigative protocol opportunities to develop liaisons with practicing physicians nearby as well as at some distance and to provide an organizational framework that will make participation in these protocols practical for a larger segment of our brain-tumor patient population. Between 1980 and 1985, the increased use of magnetic resonance imaging in neuroradiology is apparent as well as the increased use of stereotactic biopsy and interstitial radiotherapy. Complications of therapy seem acceptably low. Five-year survival for benign brain tumor is high, while that for the most common primary tumor, glioblastoma multiforme, is only 5.5%. Some of the findings in this survey confirm those from the literature while others, particularly the pattern of care, represent new data.

National survey of patterns of care for testis cancer.

A national survey of testicular cancer documented recent trends in disease characteristics, treatment, and outcome, providing a basis for progress being achieved on a community basis. A long-term study of 3285 patients diagnosed between 1970 and 1975 was compared with a short-term study of 1887 patients diagnosed in 1983. An increase of the symptom of a lump in the testis from 23.1% to 31.2% and a mass as a sign of cancer from 44.5% to 53.8% suggests earlier detection of testis cancer by the patient and physician. Changes in the methods of diagnosis reflect the changing technology of tumor diagnosis. The 10-year survival rates for pathologic Stage I seminoma (82.6% of all seminomas) exceeded 96%. For pathologic Stage I nonseminomatous germ cell tumors (51.7% of all NSGCT), 10-year survival was 87.1%; whereas for Stage III (18.7% of all NSGCT) it was 22.1%. The impact of the important advances in chemotherapy is reflected in the increase of 1-year survival of Stage III NSGCT from 50.5% to 78.4%. Testis cancer can be cured in most patients.

Trends in patterns of care for prostatic cancer, 1974-1983: results of surveys by the American College of Surgeons.

Data from a recent survey of patterns of care for prostatic cancer sponsored by the American College of Surgeons suggest several trends compared to similar data from a decade ago. The observed differences include increased diagnosis of localized cancer, and increased use of acid phosphatase determinations, bone scans, radical retropubic prostatectomy, radiotherapy (particularly interstitial techniques) and orchiectomy. In contrast, use of bone surveys, perineal prostatectomy and hormonal therapy has decreased. Transurethral resection continues to be the most common means to establish the diagnosis of prostatic cancer but the data do suggest that in more patients the tumors are being staged and graded. Five-year survival rates appear to be improving for all stages, and for white and black patients. Survival of black patients continues to lag behind that of white subjects, presumably owing to the more advanced stage of disease at diagnosis observed in these data. These findings may have important implications for understanding trends in survival of patients with this disease.

Condition and type of housing as an indicator of potential environmental lead exposure and pediatric blood lead levels.

Environmental evaluations in a prospective behavioral study of children with blood lead levels up to about 50 micrograms/dl were performed by an intensive environmental survey and by exterior visual evaluation of housing quality. Serial blood lead values for infants in the study were compared to exterior housing type and quality, which itself was also compared with results of the intensive environmental evaluation. Five housing condition and type categories were defined: public housing; private housing (satisfactory, deteriorated, and dilapidated); and rehabilitated private housing. In this interim report on the first subset of available data, the housing categories were found to differ in paint and environment dust lead levels, with public and rehabilitated housing having lowest values. Blood lead concentrations of children differed across housing categories as early as 6 months of age, with children residing in public housing having lowest levels, followed by those in rehabilitated housing. The spread in mean blood lead concentrations among the housing quality categories increased with increasing age of the children. Housing category accounted for over one-half of the blood lead variability in 18-month-old children.

Evolution of efficient methods to sample lead sources, such as house dust and hand dust, in the homes of children.

Efficient sampling methods to recover lead-containing house dust and hand dust have been evolved so that sufficient lead is collected for analysis, and to ensure that correlational analyses linking these two parameters to blood lead are not dependent on the efficiency of sampling. Precise collection of loose house dust from a 1-unit area (484 cm2) with a Tygon or stainless steel sampling tube connected to a portable sampling pump (1.2 to 2.5 liters/min) required repetitive sampling (three times). The Tygon tube sampling technique for loose house dust less than 177 microns in diameter was around 72% efficient with respect to dust weight and lead collection. A representative house dust contained 81% of its total weight in this fraction. A single handwipe for applied loose hand dust was not acceptably efficient or precise, and at least three wipes were necessary to achieve recoveries of greater than 80% of the lead applied. House dusts of different particle sizes less than 246 microns adhered equally well to hands. Analysis of lead-containing material usually required at least three digestions/decantations using hot plate or microwave techniques to allow at least 90% of the lead to be recovered. It was recommended that other investigators validate their handwiping, house dust sampling, and digestion techniques to facilitate comparison of results across studies. The final methodology for the Cincinnati longitudinal study was three sampling passes for surface dust using a stainless steel sampling tube; three microwave digestions/decantations for analysis of dust and paint; and three wipes with handwipes with one digestion/decantation for the analysis of six handwipes together.

Mesothelioma associated with the shipbuilding industry in coastal Virginia.

A case-control study was undertaken to clarify reasons for a four-fold increased incidence of mesothelioma discovered among white males in coastal Tidewater, Va., from 1972 to 1978. Sixty-one cases were identified. Interviews with next of kin revealed that the excess was linked to employment in area shipyards. Three-fourths of the cases had been employed in the shipbuilding industry, nearly all beginning employment prior to 1950. Most were career employees, but an increased risk was also found among those who worked only temporarily, mainly during World War II, and were reportedly exposed to asbestos. More of the cases than controls were pipecoverers or pipefitters, but cases were reported to work in a variety of shipyard trades. Few of the mesothelioma cases were heavy smokers, a trend that may be related in part to the competing risks for fatal diseases caused by the interactions of smoking and asbestos exposure. Information obtained by interview for five of the six white females diagnosed with mesothelioma revealed that the husband of four had been employed in the shipbuilding industry.