Laboratory facility to create reference radon + thoron atmosphere under dynamic exposure conditions

Radon (²²²Rn) and thoron (²²⁰Rn) levels in the environment are typically subject to significant random and systematic variations. Creation in the laboratory of reproducible and controlled exposure conditions close to that in the real environment can be useful for testing ²²²Rn and ²²⁰Rn detectors and for research. In this report the design and performance of a novel laboratory facility with such functionality is presented. The facility allows the exposure of detectors under controlled dynamic as well as static activity concentrations of ²²²Rn and ²²⁰Rn (pure and mixed) and temperature. The temperature is measured and regulated within -15 °C ÷ +60 °C by a dedicated programmable thermostat. Different reference activity concentrations in the exposure vessel are made by regulating the flow-rate of the air that flushes ²²²Rn/²²⁰Rn activity from the sources towards the exposure vessel. Reference atmospheres that contain ²²²Rn, ²²⁰Rn or a specified ratio of the two can be created. Pilot experiments that demonstrate the feasibility of the approach are presented. They include follow-up of a pre-defined temperature profile (in the range -5 °C ÷ +35 °C), test of the correspondence between planned and measured ²²²Rn and ²²⁰Rn activity concentrations, follow-up of a pre-defined dynamic profile of ²²⁰Rn concentrations and test of the possibility to create mixed ²²⁰Rn/²²²Rn atmospheres (experimentally checked for ratio of the activity concentrations from 0.27 to 4.5). The results from the experimental tests are in agreement with the values obtained by the developed theoretical model. The proposed approach can be used to plan and create stationary and dynamic reference exposure conditions that are close to the real exposure regimes in the environment.

A high-sensitivity method for the measurement of 222Rn based on liquid scintillation counting of polycarbonate powder

This work describes a technique for the measurement of 222Rn by absorption in polycarbonate (PC) powder and liquid scintillation counting (LSC). The work is an improvement of the recently proposed method for 222Rn measurements by LSC of exposed PC grains. It is demonstrated that the use of PC powder as a 222Rn sampler improves 13.6 times the sampling efficiency and leads to 6.5 times smaller minimmal detectable activity concentrations (MDAC) compared with the PC grains used so far. For a 40-h exposure of 7.4-g PC powder to 222Rn in air, the MDAC with a RackBeta 1219 LS counter is 62 Bq m(-3) (assuming a 8-h sample counting time and 24-h background time). For the same conditions the estimated 222Rn MDAC with a Quantulus 1220 LS counter is 20 Bq m(-3). The proposed technique is suitable for radon in air and radon in soil-gas measurements.

Liquid scintillation counting of polycarbonates: a sensitive technique for measurement of activity concentration of some radioactive noble gases

This work explores the application of the liquid scintillation counting of polycarbonates for measurement of the activity concentration of radioactive noble gases. Results from experimental studies of the method are presented. Potential applications in the monitoring of radioactive noble gases are discussed.

Long-term consequences of anesthetic technique after cancer surgery

The main treatment for most types of malignant tumors is their surgical removal. During the past years there has been a growing interest in the anesthesia effects on long-term surgery results in connection with cancer. Modern clinical and laboratory data indicate that the anesthetic technique may play a role in tumor dissemination and recurrence. The purpose of this study is to review the available literature data on the anesthetic techniques applied in oncology surgery, long-term consequences of anesthesia/analgesia and their relation to tumor progression.

MATERIAL AND METHODS

We have reviewed the specialized medical literature and have analyzed the effects of anesthesia/analgesia on long-term results of surgical treatment--incidence of local recurrence, metastases and patients' survival.

RESULTS

The hypothesis about the influence of the anesthesia type on long-term results after cancer surgery is generated. The use of anesthetics and analgesics with low potential for immunosuppression may reduce the relapse. This is a useful approach for patients with cancer.

IN CONCLUSION

Further randomized controlled trials are required for extensive research of this problem.

Combined mutation of Vhl and Trp53 causes renal cysts and tumours in mice

The combinations of genetic alterations that cooperate with von Hippel–Lindau (VHL) mutation to cause clear cell renal cell carcinoma (ccRCC) remain poorly understood. We show that the TP53 tumour suppressor gene is mutated in approximately 9% of human ccRCCs. Combined deletion of Vhl and Trp53 in primary mouse embryo fibroblasts causes proliferative dysregulation and high rates of aneuploidy. Deletion of these genes in the epithelium of the kidney induces the formation of simple cysts, atypical cysts and neoplasms, and deletion in the epithelia of the genital urinary tract leads to dysplasia and tumour formation. Kidney cysts display a reduced frequency of primary cilia and atypical cysts and neoplasms exhibit a pro-proliferative signature including activation of mTORC1 and high expression of Myc, mimicking several cellular and molecular alterations seen in human ccRCC and its precursor lesions. As the majority of ccRCC is associated with functional inactivation of VHL, our findings suggest that for a subset of ccRCC, loss of p53 function represents a critical event in tumour development.

[Hypotension and hydration during spinal anesthesia for caesarean section]

Spinal anesthesia is the technique of choice for elective cesarean section. It is easily achievable, fast and reliable technique. Maternal hypotension is a complication of spinal anesthesia, which is associated with adverse effects on both the mother and the fetus. Thus, the aim of the anesthesiologists should be to treat maternal hypotension quickly and efficaciously, or better yet, to actively prevent it. In current practice the application of vasopressors to maintain arteriolar tone is the most widely used strategy for the prevention of hypotension induced by spinal anesthesia. Other methods such as left tilt of the operating table, decreasing aortocaval compression and hydration are also routinely applied. Possible four different methods of intravascular hydration: (1) crystalloid preloading, (2) colloid preloading, (3) crystalloid co loading, and (4) colloid co loading.

Cytological and molecular evidence of deletion of ribosomal RNA genes in chromosome 6 of barley (Hordeum vulgare)

The barley chromosomal mutant T-35, in which only one pair of satellite chromosomes is apparent, was analyzed using a range of cytological and molecular techniques. Using conventional Feulgen staining, Giemsa and silver banding, in situ hybridization, and Southern blot analysis, unequivocal cytological and molecular evidence was obtained that T-35 is a homozygous deletion of rRNA genes residing in the nucleolus organizer region (NOR) of chromosome 6. According to the criteria of arm ratio and Giemsa-banding pattern of this chromosome, the deletion involved the whole NOR, one of the breakpoints being localized in the short arm proximally to the NOR-associated heterochromatic band, the other probably in the satellite of the chromosome. As a result of this deletion, an increased activity of the rRNA genes (as indicated by the size of the silver bands) on the other NOR-bearing chromosome (chromosome 7) was observed. The possible reasons for this phenomenon are discussed.

p53 suppresses type II endometrial carcinomas in mice and governs endometrial tumour aggressiveness in humans

Type II endometrial carcinomas are a highly aggressive group of tumour subtypes that are frequently associated with inactivation of the TP53 tumour suppressor gene. We show that mice with endometrium-specific deletion of Trp53 initially exhibited histological changes that are identical to known precursor lesions of type II endometrial carcinomas in humans and later developed carcinomas representing all type II subtypes. The mTORC1 signalling pathway was frequently activated in these precursor lesions and tumours, suggesting a genetic cooperation between this pathway and Trp53 deficiency in tumour initiation. Consistent with this idea, analyses of 521 human endometrial carcinomas identified frequent mTORC1 pathway activation in type I as well as type II endometrial carcinoma subtypes. mTORC1 pathway activation and p53 expression or mutation status each independently predicted poor patient survival. We suggest that molecular alterations in p53 and the mTORC1 pathway play different roles in the initiation of the different endometrial cancer subtypes, but that combined p53 inactivation and mTORC1 pathway activation are unifying pathogenic features among histologically diverse subtypes of late stage aggressive endometrial tumours.

Abstract 3293: p53 suppresses type II endometrial carcinomas in mice and governs endometrial tumour aggressiveness in humans

Type II endometrial carcinomas are a highly aggressive group of tumour subtypes that are frequently associated with inactivation of the TP53 tumour suppressor gene. We show that mice with endometrium-specific deletion of Trp53 initially exhibited histological changes that are identical to known precursor lesions of type II endometrial carcinomas in humans and later developed carcinomas representing all type II carcinoma subtypes. The PI3K-Akt-mTOR signalling pathway was frequently activated in these precursor lesions and tumours, suggesting a genetic cooperation between this pathway and Trp53 deficiency in tumour initiation. Consistent with this idea, immunohistochemical analyses of 521 human endometrial carcinomas identified frequent mTOR pathway activation in type I as well as type II endometrial carcinoma subtypes and mTOR pathway activation and p53 expression each independently predicted poor patient survival. We suggest that molecular alterations in p53 and the PI3K-mTOR pathway play different roles in the initiation of the different endometrial cancer subtypes, but that combined p53 inactivation and PI3K-mTOR pathway activation are unifying pathogenic features among histologically diverse subtypes of late stage aggressive endometrial tumours.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3293. doi:1538-7445.AM2012-3293