Uncertainties in TDCR measurement revisited: Contribution of optical effects

In the Triple to Double Coincidence Ratio method in Liquid Scintillation Counting, the detection efficiency is calculated from the value of a free parameter describing the intrinsic light yield of the counting system. This model is generally based on a Poisson distribution of the number of photoelectrons detected and the detection efficiency is obtained from the complement of the non-detection efficiency. In the classical free parameter model, the mean of the Poisson distribution, m, is a constant but some variability of this mean could be expected from optical effects due to internal reflections inside the LS source or from non-homogeneity of the detection efficiency of the photomultiplier tubes. Then, m becomes a random variable and the distribution of the photoelectrons becomes a compound Poisson distribution, with a random variable as mean value. This paper explores the implications of the variance of m, which were, to our knowledge, never considered previously in the uncertainty budget of TDCR measurements.

Long-term outcomes following transcatheter pulmonary valve implantation with the sapien 3 valve: an international multicentre registry

Background

Transcatheter pulmonary valve implantation (TPVI) is indicated to treat right-ventricular outflow tract dysfunction related to congenital heart disease. Long-term outcomes following TPVI with the new-generation SAPIEN 3 valve are not well documented.

Purpose

We investigated mid-term outcomes in a large cohort of patients who underwent TPVI using the SAPIEN 3 valve.

Methods

We retrospectively analysed data from a multicentre observational registry of patients who underwent TPVI with SAPIEN 3 in 30 centres in 12 countries from Europe, the Middle East, and Canada. Patient-related, procedural, and mid-term-outcome data were assessed.

Results

We obtained data for 713 patients treated in 2014–2021. Number of procedures performed among centres varied from 1 to 190 with a median of 15. Median age was 29.4-year-old [19.0–42.8]. The most common underlying diagnosis was cono-truncal defect (68.9%), with a native or patched right-ventricular outflow tract, a bioprosthetic valve, a homograft and a conduit, in 50.8%, 19.6%, 16.5% and 13.2% patients, respectively. Pre-stenting was performed in 74.8% patients. The 20-mm, 23-mm, 26-mm, and 29-mm valves were used in 0.4%, 28.2%, 31.2%, and 40.2% of patients, respectively. Valve implantation was successful in 98.6% patients. Life-threatening peri-procedural adverse events occurred in 3.7% patients, including 0.6% peri-procedural death. Median follow-up was 1.4 years (maximum, 5.9 years; 1160 patient-years), At last follow-up, pulmonary regurgitation grade 2, 3 and 4 was noted in 6.9%, 0.9% and 0.0% patients, respectively. Median maximal gradient at last follow-up was 18 mmHg.

Six patients experienced infective endocarditis (0.5 per 100 patient-years) of whom 1 died and 2 required pulmonary valve replacement. Nine patients (0.8 per 100 patient-years) had secondary pulmonary valve replacement (including 2 by valve-in-valve TPVI; 7 patients had 23-mm and 2 had 26-mm valves). Four patients experienced pulmonary valve thrombosis (0.6 per 100 patient-year) of whom one died and 3 resolved under anticoagulation therapy.

Cumulative incidences of infective endocarditis, secondary pulmonary valve replacement and valve thrombosis were 0.7%, 1.3% and 1.3%; 0.4%, 1.3% and 4.6%; 0.5%, 0.5% and 0.8% at 1, 3 and 5 years after TPVI respectively.

Conclusion

TPVI with the SAPIEN 3 valve was feasible and safe in a wide range of patients with congenital heart defects, most of whom had large native right-ventricular outflow tracts. Mid-term outcomes were favourable.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): The study is promoted and financially supported by a Research grant of the Groupe Hospitalier Paris Saint Joseph

Approaches for reduction of the temperature bias on radon detectors packed in anti-thoron polymer membranes

Passive and active detectors used for radon (²²²Rn) measurements can be influenced by thoron (²²⁰Rn). Polyethylene membranes are very appropriate diffusion barriers for anti-thoron protection of such detectors. However, if not properly chosen, these membranes may not reduce efficiently the thoron influence or could introduce temperature bias in the radon sensitivity of the detectors. In this work three approaches are proposed dealing with the thoron influence and the temperature bias introduced by packing in polymer membranes. The approaches exploit a model of the radon and thoron diffusion transport through the membranes and the already known diffusion properties of the membranes to estimate the thoron influence and the temperature bias and to take them into account. The approaches are experimentally verified. It is shown that, in some cases, with the proper choice of membrane the thoron influence could be reduced down to few percents introducing only a few percents temperature bias. Additionally, in the cases when temperature bias is significant and cannot be avoided (the thoron bias in that cases is shown to be below 1%), the proposed approaches allow to estimate and to correct that bias.

[First results of clinical diagnostic analysis of post-COVID peripheral neuropathy]

This analysis of ocular manifestations of the COVID-19 that can occur both in the acute and the post-COVID period focuses on pathological changes associated with hypercoagulation: thrombosis of the central retinal vein, occlusion of the central retinal artery, and decreased peripapillary perfusion. Potential changes in corneal nerve fibers (CNF) associated with coronavirus infection remain poorly understood. Meanwhile, previous studies have shown the possibility of using CNF as biomarkers of polyneuropathy (PNP).

PURPOSE

To study clinical and diagnostic features of post-COVID PNP.

MATERIAL AND METHODS

We examined 9 female patients aged 32 to 51 years who had suffered an infection caused by SARS-CoV-2 of varying severity. The patients were divided into two groups: the first consisted of 6 patients with clinical manifestations of PNP in the form of neuropathic pain, the second - 3 patients without clinical manifestations. Patients of group 1 underwent comprehensive examination including neurological examination, confocal microscopy of the cornea (in vivo CM), electroneuromyography (ENMG) of the nerves of the upper and lower extremities, quantitative sensory testing in the zone of painful sensations, while patients of group 2 only underwent in vivo CM.

RESULTS

All patients of the first group, within 5-40 days after the onset of infection caused by SARS-CoV-2, exhibited symptoms of damage to various parts of the nervous system (peripheral nerves, thoracic spinal roots, trigeminal nerve). The main - and in most cases the only - symptom of the disease was neuropathic pain syndrome. In Guillain-Barré syndrome, for the first time using in vivo CM, the following changes were revealed: enlargement of in Langerhans cells, shortening of CNF and their processes, presence of neuromas.

CONCLUSION

The standard neurological examination of patients with post-COVID neuropathy should be supplemented with special diagnostic methods for assessment of structural and functional state of the peripheral nerves. The in vivo CM method is capable of non-invasive assessment of changes in thin CNF and, with accumulation of empirical data, can be included in the algorithm for diagnosing post-COVID PNP.

Partition Coefficients and Diffusion Lengths of 222Rn in Some Polymers at Different Temperatures

In this work, the partition coefficients K and diffusion lengths LD of radon in some polymers are experimentally determined for several temperatures in the range T = 5–31 °C. Some of the obtained values are compared to published data available for the given temperatures. It is shown that the temperature dependencies of the partition coefficients K(T), the diffusion lengths LD(T), and the permeabilities P(T) could be described analytically for the studied temperature range 5–31 °C. This allows estimation of these quantities in the given temperature range and quantitative description of the transport of radon in the studied polymers.

Testing and Calibration of CDs as Radon Detectors at Highly Variable Radon Concentrations and Temperatures

The application of the compact disk (CD) method for radon measurements at mines, caves and other workplaces needs testing under highly variable exposure conditions. We present the results from a blind comparison of CDs exposed in the Laboratory of Natural Radiation (Saelices el Chico, Spain). During the exposure the temperature varied from 6.5 to 24.9 °C (average 12.6 °C) and the ²²²Rn activity concentrations varied from <10 Bq m⁻³ to 147 kBq m⁻³. Good correspondence was observed between the integrated ²²²Rn activity concentration determined by the reference instruments in the laboratory (122,500 ± 6100 kBq h m⁻³) and that assessed by analysis of the CDs at a depth 80 µm beneath the front surface (118,000 ± 12,000 kBq h m⁻³) and at a depth of 120 µm (106,000 ± 12,000 kBq h m⁻³). The theoretical modeling of the CD response under variable temperature and radon concentration suggested that the small bias is probably due to the time variation of the calibration factor because of the time variations of the temperature.

Identifying radon priority areas and dwellings with radon exceedances in Bulgaria using stored CD/DVDs

The implementation of the 2013/59/EURATOM directive in the part related to radon exposure imposes challenges for radon measurement methodology and radon survey design. Among them is the need to have estimates (preferably direct) of the annual average radon concentrations, which can be directly compared to the recommended reference levels. On this basis, the surveys should make possible the identification of dwellings with indoor radon above the reference levels and "radon priority areas" where significant proportion of the dwellings falls in this category. The performance of the CD/DVD method for radon measurements as a tool to address these issues is presented. A recent large scale field study based on the CD/DVD method that was carried out in the suburb area of Sofia, Bulgaria is described. Part of the studied area was affected in the past by the uranium mining and milling industry. In total 462 disks (CDs and DVDs) taken from 335 private dwellings from 10 districts in the region were analyzed. The results revealed the large heterogeneity in radon distribution in the area, with the percentage of dwellings with a ²²²Rn level above 300 Bq m^-3 ranking from about 7% to 74%. The district of Yana, for which this percent was 74, was identified as the area of highest radon priority in the region. The paper also discusses how prompt identification of dwellings with radon above the reference level by CD/DVDs can be incorporated within an integrated approach to the radon problem. Within this approach the radon hazard is identified shortly after the stakeholder's decision to test, which allows fast solution of the problem without waiting the long (and usually demotivating) one-year period needed for direct results by the commonly used prospective methods.

Unperturbed, high spatial resolution measurement of Radon-222 in soil-gas depth profile

This work presents a method for measuring the depth distribution of ²²²Rn activity in soil gas. The method is based on the capacity of polycarbonates to absorb ²²²Rn and on the possibility of performing sensitive measurements of ²²²Rn absorbed by the polycarbonates via liquid scintillation counting (LSC). The method is the following: cylindrical holes are drilled along a metal rod and Makrofol^® N polycarbonate foils enclosed in polyethylene envelopes are placed in each hole. The rod is driven into the soil and kept for a certain time. As long as the rod is in the soil, the polycarbonate foils are exposed to the ²²²Rn concentration at their depth. At the end of the exposure the rod is pulled out and the foils are transferred to liquid scintillation (LS) vials filled with liquid scintillator. The ²²²Rn absorbed in the foils is then measured with a LS analyzer. The rod with the polycarbonate foils acts as a passive probe which senses the ²²²Rn concentration at different depths beneath the ground surface. The achievable minimum detectable ²²²Rn activity concentration with the equipment and conditions used in this study is around 12.5 kBq/m³. It can easily be lowered below 1 kBq/m³ if larger foils and low-background LS analyzers are used. Since the method does not require air sampling the depth distribution of ²²²Rn in the soil is unperturbed by the sampling. The spatial distribution and the maximum measurement depth are set by the distance between the holes and the depth to which the rod can be fixed into the ground. Results from in situ applications of the method in terrains with high ²²²Rn in soil-gas are reported, which demonstrate the feasibility and the usefulness of the proposed approach.

RADON-222 IN SOIL-GAS MEASUREMENTS BY COMPACT DISCS. COMPARISON TO DIFFUSION CHAMBER MEASUREMENTS

This work presents the results from simultaneous measurements of 222Rn in soil-gas by compact discs (CDs) and diffusion chambers. The measurements were performed in three terrains with high, medium and low 222Rn-in-soil-gas concentrations. Good correlations between the CD measurements and the reference diffusion chamber measurements are observed. The results indicate that it is important to apply temperature correction in the CD measurements, in order to account for the actual temperature during the exposure of the CDs in the soil.

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