Production of 117mSn and 119mSn by photonuclear reactions on natural antimony.

Natural antimony targets were irradiated in a 60 MeV bremsstrahlung beam and gamma spectrometric measurements were performed. The goal was to establish the yield of 117mSn, a radionuclide with great potential for application in medicine. Considering that 117mSn is predominantly produced through a photonuclear reaction in which an charged particle is emitted (121Sb(γ,p3n)), the yield of this tin isotope is much lower than the yields of several antimony isotopes produced in (γ,xn) reactions. It has been estimated that photonuclear reactions on natural antimony could produce 117mSn activities needed for therapeutic applications, with accelerators having electron currents of the order of mA. For the used bremsstrahlung energy of 60 MeV, it was estimated how much 119mSn activity can be expected when exposing the antimony target.

Correlation analysis of the natural radionuclides in soil and indoor radon in Vojvodina, Province of Serbia.

The most dominant source of indoor radon is the underlying soil, so the enhanced levels of radon are usually expected in mountain regions and geology units with high radium and uranium content in surface soils. Laboratory for radioactivity and dose measurement, Faculty of Sciences, University of Novi Sad has rich databases of natural radionuclides concentrations in Vojvodina soil and also of indoor radon concentrations for the region of Vojvodina, Northern Province of Serbia. In this paper we present the results of correlative and multivariate analysis of these results and soil characteristics in order to estimate the geogenic radon potential. The correlative and multivariate analysis were done using Toolkit for Multivariate Analysis software package TMVA package, within ROOT analysis framework, which uses several comparable multivariate methods for our analysis. The evaluation ranking results based on the best signal efficiency and purity, show that the Boosted Decision Trees (BDT) and Multi Layer Preceptor (MLP), based on Artificial Neural Network (ANN), are multivariate methods which give the best results in the analysis. The BDTG multivariate method shows that variables with the highest importance are radio-nuclides activity on 30 cm depth. Moreover, the multivariate regression methods give a good approximation of indoor radon activity using full set of input variables. On several locations in the city of Novi Sad the results of indoor radon concentrations, radon emanation from soil, gamma spectrometry measurements of underlying soil and geology characteristics of soil were analyzed in detail in order to verify previously obtained correlations for Vojvodina soil.

Daily and seasonal radon variability in the underground low-background laboratory in Belgrade, Serbia.

Radon time-series analysis, based on the short-term indoor radon measurements performed worldwide, shows two main periodicity: daily and seasonal. The information obtained from time series of the measured radon values is the results of the complex radon dynamics that arises from the influence of the large number of different parameters (the state of the indoor atmosphere (temperature, pressure and relative humidity, aerosol concentration), the exchange rate between indoor and outdoor air and so on). In this paper we considered daily radon variability in the underground low-background laboratory in Belgrade, Serbia. The results are originated from the radon time-series analysis based on the 3 y of the continuous short-term indoor radon measurements. At the same time, we obtained the time series of the temperature, pressure and relative humidity in the laboratory. We also tried to find the correlation between different time series.

The effects of the somatostatin analogue octreotide on ovulatory performance in women with polycystic ovaries.

The elevated luteinizing hormone (LH) and androgen concentrations characteristic of women with polycystic ovaries (PCO) are considered crucial factors in their infertility. The somatostatin analogue octreotide lowers LH and androgen concentrations in women with PCO. The effects of octreotide given concurrently with human menopausal gonadotrophin (HMG) were therefore compared with that of HMG alone in 28 infertile women with PCO resistant to clomiphene. In 56 cycles of combined HMG and octreotide therapy there was more orderly follicular growth compared with the multiple follicular development observed in 29 cycles in which HMG was given alone (mean number of follicles > 15 mm diameter on the day of human chorionic gonadotrophin (HCG) administration: 2.5 +/- 0.2 and 3.6 +/- 0.4 respectively; P = 0.026). There was a significantly reduced number of cycles abandoned (> 4 follicles > 15 mm diameter on day of HCG) in patients treated with octreotide+HMG, so that HCG had to be withheld in only 5.4% of cycles compared to 24.1% with HMG alone (P < 0.05). The incidence of hyperstimulation was also lower on combined treatment. Octreotide therapy resulted in a more 'appropriate' hormonal milieu at the time of HCG injection, with lower LH, oestradiol, androstenedione and insulin concentrations. Although growth hormone concentration was similar on both regimens, significantly higher insulin growth factor-I concentrations were observed on the day of HCG in women on combined therapy than on HMG alone.

Effects of the somatostatin analogue, octreotide, in polycystic ovary syndrome.

In view of the association of hyperinsulinemia with elevated luteinizing hormone (LH) levels and hyperandrogenism in polycystic ovary syndrome (PCOS), the effect of octreotide was investigated in women with PCOS. Twelve amenorrheic women were treated with 100 micrograms octreotide twice a day for 7 days; 13 infertile women unresponsive to clomiphene citrate were treated either with octreotide (100 micrograms twice a day from day 1 of the menstrual cycle until corpus luteum formation) in addition to human menopausal gonadotropins (HMG) or with HMG alone. Octreotide significantly reduced the 4-hour integrated LH concentrations. LH pulse amplitude and nadir concentrations, and LH, testosterone, androstenedione, and estradiol responses to a gonadotropin-releasing hormone (GnRH) analogue in amenorrheic PCOS women. Octreotide treatment also resulted in a more "appropriate" hormonal milieu at the time of human chorionic gonadotropin (HCG) injection in the infertile women, with LH and testosterone levels being reduced while follicle-stimulating hormone (FSH) levels increased. Orderly follicular growth occurred, with one or two mature follicles being present at the time of HCG injection in cycles in which octreotide was given together with HMG. There were no cases of hyperstimulation, even in women who had previously hyperstimulated after HMG alone. Octreotide thus inhibits LH and androgen secretion and may improve ovulatory performance in infertile women with PCOS.