Radiosensitizing effects of gemcitabine on aerobic and chronically hypoxic HeLa and MRC5 cells in-vitro

Gemcitabine [2', 2'-difluoro-2'- deoxycytidine, an analogue of deoxycytidine] is a relatively new drug with wide range of anti-cancer activity. In this study, radiosensitizing effects of gemcitabine was investigated on HeLa and MRC5 human originated cell lines under both chronically hypoxic and normoxic conditions using the micronucleus [MN] assay. For induction of chronic hypoxia, the cell culture flasks were saturated with N2 gas. To evaluate the radiosensitizing effects, in the presence of the non-genotoxic concentration [1ng/ml] of gemcitabine, cells were exposed to different doses [0.5, 1, 2 Gy] of X-ray in both chronically hypoxic and normoxic conditions. Results showed that there was no significant difference in MN induction under chronically hypoxic and normoxic condition when using 1 ng/ml gemcitabine alone, however in the absence of drug, MN induction was significantly different in irradiated cells [P<0.01]. Radiosensitizing effects of gemcitabine in chronic hypoxic condition was greater than normoxic condition in both cell lines [P<0.01], although more pronounced in HeLa cells. Radiosensitizing effects and greater dose modifying factor of gemcitabine under depleted oxygen condition is not clearly understood. It might be due to depletion of deoxynocleotides pools via inhibition of ribonucleotide reductase and mismatched nucleosides incorporation into DNA after radiation exposure

Experimental and Monte Carlo studies on the response of CR-39 detectors to Am-Be neutron spectrum

The Poly-Allyl Diglycol Carbonate [PADC] detector is of particular interest for development of a fast neutron dosimeter. Fast neutrons interact with the constituents of the CR-39 detector and produce H, C and 0 recoils, as well as [n, a] reaction. These neutron- induced charged particles contribute towards the response of CR-39 detectors. Material and Electrochemical etching was used to enlarge track diameter which was made by low energy recoil protons. Before electrochemical etching, a chemical etching was performed for 1 hour. The responses were also calculated by Monte Carlo simulations, using MCNPX code in different energy bins considering H, C and O recoils. The total registered efficiency and partial contributions of the efficiency, due to interactions with each constituent of CR-39, were calculated. The optimized condition of etchant was obtained to be 6N KOH 15kV.cm[1], and 6 hours etching time. The obtained results show that track efficiency of CR-39 was a function of incident neutron energy. The tracks caused by O and C recoil nuclei were negligible for neutron energies lower than 1 MeV. At neutron energies lower than 1 MeV, only recoil protons would have sufficient energy to leave visible tracks. But, O and C recoils had important contributions in overall response of PADC at neutron energies of few MeV. The efficiency of a CR-39 based dosemeter could be calculated by MCNPX code and the results were in a good agreement with experimental results in energy range of [241]Am - Be bare source and [241]Am-Be was softened with a spherical polyethylene moderator of radius of 20 cm

[Achieving the goals of integration of medical education and health service delivery systems from the viewpoint of the faculty members of Kermanshah university of medical sciences]

Plan of integration of the schools of medicine and health systems was approved in 1985. Considering the importance of the opinion the faculty members on achieving success on this issue, we decided to perform this study. We used a questionnaire consisted of 27 questions in various fields. Also the questions were categorized in the education, research, treatment, health and social fields. After completing the questionnaire, score of every question was determined. According to demographic information of the participants, scores of the different fields and also between different fields were analyzed by means of ANOVA, Friedman and paired T test. From the viewpoint of the faculty members, achievement of the goals of integration on the average was 52.37 +/- 1.07 [Mean +/- SEM] percent of the maximum scores. The highest scores belonged to health services and health indicators [59.87% +/- 1.21] and the least scores were related to research facilities and activities and social purposes of integration plan [49.19% +/- 1.20] [P=0.0001]. From the viewpoint of the faculty members, success in achieving integration plan goals is still far from ideal state. Success of this plan in the health field was significantly higher than that of education and treatment fields. Also the success of this plan in the research and social fields [such as changing the sociological insight of the graduates and faculty members] was significantly lower, compared with the other fields. These differences may be due to a failure in the current system to achieve some of its goals. Similar studies on this subject, in other centers are recommended

Determination of [40]K concentration in milk samples consumed in Tehran-Iran and estimation of its annual effective dose

Since [40]K is the most important natural radionuclide in the environment, its concentration was measured for all milk and milk powder samples consumed in Tehran-Iran. Milk was chosen, since because it is a reliable indicator of the general population intake of certain radionuclide, and many environmental programs have been applied for its safety. Measurements was done using a CANBERRA gamma spectrometer Model No. S100. Forty one milk and milk powder samples were choosen for the gamma spectroscopy analysis. The average activity concentrations for [40]K in the samples were calculated, 31.0 +/- 6.1 and 17.1 +/- 3.3 Bq.kg[-1], in milk and milk powder respectively. These data correspond to the effective dose of 14 micro Sv.year[-1] for adults and in the range of 6.4-15.9 micro Sv.day[-1] for children. Considering the obtained data from liquid milk samples, an almost uniform distribution of [40]K can also be obtained. Furthermore, the calculated effective doses were too low to induce important health hazards; however, the data useful for monitoring

Comparison of logistic regression and neural network models in predicting the outcome of biopsy in breast cancer from MRI findings

We designed an algorithmic model based on the logistic regression analysis and a non-algorithmic model based on the Artificial Neural Network [ANN]. Materials and methods: The ability of these models was compared together in clinical application to differentiate malignant from benign breast tumors in a study group of 161 patients' records. Each patient's record consisted of 6 subjective features extracted from MRI appearance. These findings were encoded as features for an ANN as well as a logistic regression model [LRM] to predict biopsy outcome. After both models had been trained perfectly on samples [n=100], the validation samples [n=61] were presented to the trained network as well as the established LRMs. Finally, the diagnostic performance of models were compared to that of the radiologist in terms of sensitivity, specificity and accuracy, using receiver operating characteristic curve [ROC] analysis. The average output of the ANN yielded a perfect sensitivity [98%] and high accuracy [90%] similar to that one of an expert radiologist [96% and 92%] while specificity was smaller than that [67% verses 80%]. The output of the LRM using significant features showed improvement in specificity from 60% for the LRM using all features to 93% for the reduced logistic regression model, keeping the accuracy around 90%. Results show that ANN and LRM prove the relationship between extracted morphological features and biopsy results. Using statistically significant variables reduced LRM outperformed of ANN with remarkable specificity while keeping high sensitivity is achieved