Bayesian optimization to estimate hyperfine couplings from 19F ENDOR spectra

ENDOR spectroscopy is a fundamental method to detect nuclear spins in the vicinity of paramagnetic centers and their mutual hyperfine interaction. Recently, site-selective introduction of 19F as nuclear labels has been proposed as a tool for ENDOR-based distance determination in biomolecules, complementing pulsed dipolar spectroscopy in the range of angstrom to nanometer. Nevertheless, one main challenge of ENDOR still consists of its spectral analysis, which is aggravated by a large parameter space and broad resonances from hyperfine interactions. Additionally, at high EPR frequencies and fields (⩾94 GHz/3.4 Tesla), chemical shift anisotropy might contribute to broadening and asymmetry in the spectra. Here, we use two nitroxide-fluorine model systems to examine a statistical approach to finding the best parameter fit to experimental 263 GHz 19F ENDOR spectra. We propose Bayesian optimization for a rapid, global parameter search with little prior knowledge, followed by a refinement by more standard gradient-based fitting procedures. Indeed, the latter suffer from finding local rather than global minima of a suitably defined loss function. Using a new and accelerated simulation procedure, results for the semi-rigid nitroxide-fluorine two and three spin systems lead to physically reasonable solutions, if minima of similar loss can be distinguished by DFT predictions. The approach also delivers the stochastic error of the obtained parameter estimates. Future developments and perspectives are discussed.

Luminescence dosimetry for evaluation of the external exposure in Metlino, upper Techa River valley, Southern Urals, Russia: Analysis of new results

Luminescence dosimetry was applied in the former settlement of Metlino, Southern Urals, Russia as part of a full-scale study to validate the Techa River Dosimetry System (TRDS) 2016 for the upper Techa River region. The village, which was evacuated in 1956, was located 7 km downstream of the release point of liquid radioactive waste by the Mayak plutonium facility. Several brick samples were taken from north-eastern and south-eastern walls of the granary, facing the former Techa river shoreline and floodplain. Samples were all taken at the same height and measured at different depths into the brick. For the majority of brick samples, good Optically Stimulated Luminescence properties of the quartz grains were observed. In some cases, however, strong levels of sensitization and/or signal recuperation were encountered which necessitated adjustment in the measurement protocols. Anthropogenic doses in bricks varied from 1.5 to 6.6 Gy and the horizontal profiles along both walls showed significant variation, which is explained on a qualitative basis. A dose depth profile is observed for selected samples, which is different from the dose depth profile measured and simulated for samples from the north-western wall of the granary in previous studies. This is qualitatively explained by the differences in source configuration.

External dose reconstruction at the shore of the Metlinsky Pond in the former village of Metlino (Techa River, Russia) based on environmental surveys, luminescence measurements and radiation transport modelling

The cohorts of people formerly living at the Techa River shoreline in the Southern Urals, Russia, are widely studied cohorts for the investigation of low-dose radiation effects to human health. The nuclear facilities of the Mayak Production Association (PA) discharged their radioactive effluents into the nearby Techa River, especially in the first years of operation. Health status of cohort member data is constantly being improved and updated. Consequently, there is a need to also improve and verify the underlying dosimetry, which gives information about the dose of cohort members. For the Techa River population, the dosimetry is handled in the Techa River Dosimetry System (TRDS). The present work shows results of a feasibility study to validate the TRDS at the location of the village of Metlino, a village just 7 km downstream from the Mayak PA. For this settlement there were two sources of external exposure, the contaminated banks of the Techa River and the contaminated shoreline of the nearby Metlinsky Pond. In the present study the north-western wall of a granary was used as a dose archive to validate dose estimates. Measurements of doses in brick accumulated over many decades and measurements of the current dose rate in bricks were combined with dose rate measurements in air above ground in front of the granary, historical contamination data and Monte-Carlo simulations. Air kerma estimates for 1949-1956 significantly different from zero could not be reconstructed for the Metlinsky Pond shoreline near the granary, but an upper dose limit could be estimated. Implications for TRDS-2016 are discussed.

Reconstruction of evolutionary changes in fat and toxin consumption reveals associations with gene losses in mammals: a case study for the lipase inhibitor PNLIPRP1 and the xenobiotic receptor NR1I3

The inactivation of ancestral protein-coding genes (gene loss) can be associated with phenotypic modifications. Within placental mammals, repeated losses of PNLIPRP1 (gene inhibiting fat digestion) occurred preferentially in strictly herbivorous species, while repeated NR1I3 losses (gene involved in detoxification) occurred preferentially in strictly carnivorous species. It was hypothesized that lower fat contents of herbivorous diets and lower toxin contents of carnivorous diets cause relaxed selection pressure on these genes resulting in the accumulation of mutations and ultimately to convergent gene losses. However, since herbivorous and carnivorous diets differ vastly in their composition, a fine-grained analysis is required for hypothesis testing. We generated a trait matrix recording diet and semi-quantitative estimates of fat and toxin consumption for 52 placental species. By including data from 31 fossil taxa, we reconstructed the ancestral diets in major lineages (grundplan reconstruction). We found support that PNLIPRP1 loss is primarily associated with low levels of fat intake and not simply with herbivory/carnivory. In particular, PNLIPRP1 loss also occurred in carnivorous lineages feeding on a fat-poor diet, suggesting that the loss of this gene may be beneficial for occupying ecological niches characterized by fat-poor food resources. Similarly, we demonstrated that carnivorous species are indeed less exposed to diet-related toxins suggesting that the loss of NR1I3 and related genes (NR1I2, UGT1A6) resulted from relaxed selection pressure. This study illustrates the need of detailed phenotype studies to obtain a deeper understanding of factors underlying gene losses and to progress in understanding genomic causes of phenotypic variation in mammals.

THU0493 IMPACT OF AGE, GENDER AND EDUCATION LEVEL ON THE CHOICE OF TREATMENT METHOD FOR BACK PAIN AMONG PEOPLE OVER 50 YEARS OF AGE

Background:

According to data collected by the Statistics Poland in 2014, lower back pain is the second most common complaint reported by people over the age of 60 and occurs in about 40% of them. Another 29% of respondents suffer from pain in other spine sections. Treatment of such a common condition can be a challenge due to the multitude of causes of pain, accompanying diseases and the patient’s approach to his own health.

Objectives:

The aim of the study was to investigate whether factors such as gender, age, level of education and pain severity affect self-chosen methods of treating back pain.

Methods:

A survey was conducted on students of Pomeranian Universities Of The Third Age. There were collected socio-demographic characteristics of the participants, features of back pain and detailed information on analgesic methods, including drugs, ointments, exercises and physiotherapy treatments (laser, cryotherapy, hydromassage, ultrasound, heat treatments and other). The responses of participants over the age of 50 were included in the analysis. The answers were divided into groups by age (younger - 50–69 years and older - over 70 years), sex, level of education (lower, medium and higher) and intensity of pain assessed on the VAS scale (<6 and ≥6). The collected data were compared in these groups.

Results:

546 answers were received. 291 respondents were 50-69 years old, 255 aged 70-90 and more, 86% (471) of participants were women. 43% of respondents had secondary education and the same number had higher education. Over 90% (494) declared that they have suffered from back pain. Most of them described pain as chronic (56%), the median pain intensity assessed on the VAS scale was 6 [1-10], and the mean pain intensity was 5.89 ± 1.79. 82.6% of respondents declared doing physical exercises to relieve back pain, 75.9% were using physiotherapy, 60.7% were taking analgesic drugs and 54.3% were using ointments, gels, patches and other local analgesic methods. The higher pain severity was observed in group of females (5.74 vs. 5.61, p=0.002) and people with lower education level (6.52) than in other groups (5.89 and 5.68, p=0.005). Analgesic drugs were taken more often by younger people (66.9% vs. 53.7%, p=0.003), women (62.5% vs. 49.2%, p=0.042), people of lower education level group (80.6% vs. 62.2% secondary education group vs. 52.5% higher education group, p<0.001) and by people with pain severity ≥6 (81.5% vs. 68.9%, p<0.001). Analgesic gels, ointments, patches and other pharmaceuticals were used more often only in group with higher pain severity (62.9% vs. 43.4%, p<0.001). Performing exercises to relieve pain was more often declared by women (84.4% vs. 70.8%, p=0.003) and people with higher education (85.1% vs. 81.3% secondary education group vs. 79.1% lower education group, p<0.001). The study showed that only in groups with varying intensity of pain there was a significant difference in the frequency of using physiotherapy treatments - 68.9% in group with pain severity <6 vs. 81.5% with pain severity ≥6 (p<0.001).

Conclusion:

1. The severity of pain has the greatest impact on the choice of back pain relief method, but this is not the only important factor.

2. People with lower levels of education and men less often perform physical exercises for treatment regardless of the severity of back pain.

3. In the treatment of back pain, attention should be given to recommending the patient an appropriate analgesic method, which will be easily used and more effective.

References:

Population aged 60+. Demographic structure and health. 2016. Statistics Poland.

Disclosure of Interests: :

None declared

Luminescence dosimetry for evaluation of the external exposure in Metlino, upper Techa River valley, due to the shore of the Metlinsky Pond: A feasibility study

Luminescence dosimetry was performed using bricks from the former settlement of Metlino, Southern Urals, Russia, to investigate the feasibility of validating the Techa River Dosimetry System (TRDS) 2016 for the shore of the Metlinsky Pond, upper Techa River region. TRDS is a code for estimating external and internal doses for members of the Extended Techa River Cohort. Several brick samples were taken from the north-western wall of the granary, facing the Metlinsky Pond. Samples were measured at different heights and at different depths into the bricks. Dating of the granary was performed by analyzing well shielded bricks. Assessment of the gamma dose-rate at the sample positions was done by thermoluminescent dosimeters and the dose-rate in front of the granary mapped with a dose-rate meter. Anthropogenic doses in bricks vary from 0.8 to 1.7 Gy and show an increase with sampling height. A similar height profile is observed for the current gamma dose-rate, which is compatible with the results of the dose-rate mapping. Implications for validating the TRDS are discussed.

Nitroxide Derivatives for Dynamic Nuclear Polarization in Liquids: The Role of Rotational Diffusion

Polarization transfer efficiency in liquid-state dynamic nuclear polarization (DNP) depends on the interaction between polarizing agents (PAs) and target nuclei modulated by molecular motions. We show how translational and rotational diffusion differently affect the DNP efficiency. These contributions were disentangled by measuring ¹H-DNP enhancements of toluene and chloroform doped with nitroxide derivatives at 0.34 T as a function of either the temperature or the size of the PA. The results were employed to analyze ¹³C-DNP data at higher fields, where the polarization transfer is also driven by the Fermi contact interaction. In this case, bulky nitroxide PAs perform better than the small TEMPONE radical due to structural fluctuations of the ring conformation. These findings will help in designing PAs with features specifically optimized for liquid-state DNP at various magnetic fields.

Monte Carlo simulation of dose coefficients for a fish eye lens model exposed to monoenergetic electrons

Vision is an important sense for the majority of the wildlife species, affecting their ability to find food and escape predation. Currently, no study on radiation induced cataract frequency on the fish eyes lens has been done. However, any thorough future study of this subject will require more accurate dose estimates for the fish eye lens than those currently available. For this purpose, the eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using the MCNPX Monte Carlo radiation transport code package. All results were validated against three different fish voxel models. The discrepancies between model results mainly originate from the different fish eye dimensions used in the different studies and in two of the cases the lack of a defined eye lens region. The dose conversion coefficients calculated in this work can be used to estimate the dose to the fish eye lens based on the activity concentration of the surrounding water. The model developed in this work has also demonstrated that the mathematical models still have several advantages over the voxel models.

Age-dependent comparison of monoenergetic photon organ and effective dose coefficients for pediatric stylized and voxel phantoms submerged in air

Dose rate coefficients computed using the University of Florida-National Cancer Institute pediatric series of voxel phantoms were compared with values computed using the Oak Ridge National Laboratory pediatric stylized phantoms in an air submersion exposure geometry. Simulations were conducted comparing phantoms classified within five ages: newborn, 1-year-old, 5-year-old, 10-year-old, and 15-year-old for both male and female sexes. This is a continuation of previous work comparing monoenergetic photon organ dose rate coefficients, as defined by ICRP Publication 103, for the male and female adult phantoms. With both the male and female data computed for each pediatric phantom age, effective dose rate coefficients and ratios were computed for voxel and stylized phantoms. Organ dose rate coefficients for the pediatric phantoms and ratios of organ dose rates for the voxel and stylized phantoms are provided for eight monoenergetic photon energies ranging from 30 keV to 5 MeV. Analysis of the contribution of the organs to effective dose is also provided. Comparison of effective dose rates between the voxel and stylized phantoms was within 5% between 500 keV and 5 MeV and within 10% between 70 keV and 5 MeV for phantoms  >1-year-old. Stylized newborn effective dose rates were consistently ~20% higher than the voxel counterpart, over all energies.

Comparison of Monoenergetic Photon Organ Dose Rate Coefficients for the Female Stylized and Voxel Phantoms Submerged in Air

Dose rate coefficients computed using the International Commission on Radiological Protection (ICRP) reference adult female voxel phantom were compared with values computed using the Oak Ridge National Laboratory (ORNL) adult female stylized phantom in an air submersion exposure geometry. This is a continuation of previous work comparing monoenergetic organ dose rate coefficients for the male adult phantoms. With both the male and female data computed, effective dose rate as defined by ICRP Publication 103 was compared for both phantoms. Organ dose rate coefficients for the female phantom and ratios of organ dose rates for the voxel and stylized phantoms are provided in the energy range from 30 to 5 MeV. Analysis of the contribution of the organs to effective dose is also provided. Comparison of effective dose rates between the voxel and stylized phantoms was within 8% at 100 keV and is <5% between 200 and 5000 keV.

IDACstar: A MCNP Application to Perform Realistic Dose Estimations from Internal or External Contamination of Radiopharmaceuticals

A Monte Carlo-based stand-alone program, IDACstar (Internal Dose Assessment by Computer), was developed, dedicated to perform radiation dose calculations using complex voxel simulations. To test the program, two irradiation situations were simulated, one hypothetical contamination case with 600 MBq of 99mTc and one extravasation case involving 370 MBq of 18F-FDG. The effective dose was estimated to be 0.042 mSv for the contamination case and 4.5 mSv for the extravasation case. IDACstar has demonstrated that dosimetry results from contamination or extravasation cases can be acquired with great ease. An effective tool for radiation protection applications is provided with IDACstar allowing physicists at nuclear medicine departments to easily quantify the radiation risk of stochastic effects when a radiation accident has occurred.

In vivo evaluation of the Phenox CRC mechanical thrombectomy device in a swine model of acute vessel occlusion

BACKGROUND AND PURPOSE

Mechanical thrombectomy in ischemic stroke is of increasing interest as it is a promising strategy for fast and efficient recanalization. Several thrombectomy devices have been introduced to the armentarium of mechanical thrombectomy. Currently, new devices are under development and are continuously added to the neurointerventional tool box. Each device advocated so far has a different design and mechanical properties in terms of thrombus-device interaction. Therefore, a systematic evaluation under standardized conditions in vivo of these new devices is needed. The purpose of this study was to evaluate the efficiency, thrombus-device interaction, and potential complications of the novel Phenox CRC for distal mechanical thrombectomy in vivo.

MATERIALS AND METHODS

The device was evaluated in an established animal model in the swine. Recanalization rate, thromboembolic events, vasospasm, and complications were assessed. Radiopaque thrombi (2 cm length) were used for the visualization of thrombus-device interaction during retrieval. The Phenox CRC (4 mm diameter) was assessed in 15 vessel occlusions. For every occlusion a maximum of 3 retrieval attempts were performed.

RESULTS

Complete recanalization (TICI 3/TIMI 3) was achieved in 86.7% of vessel occlusions. In 66.7% (10/15), the first retrieval attempt was successful, and in 20% (3/15), the second attempt led to complete recanalization of the parent artery. In 2 cases (13.3%) thrombus retrieval was not successful (TICI 0/TIMI 0). In 1 case (6.7%) a minor embolic event occurred in a small side branch. No distal thromboembolic event was observed during the study. Thrombus-device interaction illustrated the entrapment of the thrombus by the microfilaments and the proximal cage of the device. No significant thrombus compression was observed. No vessel perforation, dissection, or fracture of the device occurred.

CONCLUSIONS

In this small animal study, the Phenox CRC was a safe and effective device for mechanical thrombectomy. The unique design with a combination of microfilaments and proximal cage reduces thrombus compression with a consequently high recanalization and low complication rate.

Ortho-para conversion of interstitial H2 in Si

Ortho-para conversion of isolated interstitial H2 in single-crystalline Si is studied by Raman scattering. This process is suggested to be caused by the interaction of H2 with the nuclear magnetic moment of 29Si. At 77 K the ortho-to-para conversion rate is approximately 0.015 h(-1) for all Si samples employed in the experiments. At 300 K, the reverse para-to-ortho transition is observed. It occurs with a rate of roughly 0.18 h(-1) and results in a thermodynamically nonequilibrium ortho-para ratio.

Telemetric monitoring of tracheal pressure after tracheal occlusion for treatment of severe congenital diaphragmatic hernia

INTRODUCTION

Prenatal tracheal occlusion using endoscopic techniques obstructs the normal egress of lung fluid during pulmonary development and stimulates lung growth in cases of congenital diaphragmatic hernia (CDH). Although FETO might be an effective strategy for treatment of CDH, the mechanism especially due to the supposed increasing transpulmonary pressure is unknown.

OBJECTIVE

The purpose of this study was to monitor the pressure below the attached balloon in the fetal lamb telemetrically.

METHODS

Four time-dated pregnant Merino ewes underwent fetal and maternal surgery. A special prepared silicone catheter was placed below the epiglottis by laryngoscopy on day 110 or 140 of gestation. The tracheal pressure below the fixed catheter could be monitored telemetrically using the Data Sciences TA11-PA-C40 pressure device. Hundred and twenty measurement points were recorded over a period of 2 min.

RESULTS

A maximum of lung pressure rate was found immediately after implantation (23.7 +/- 4.6 mm Hg). During the first hour, the pressure decreased to an average value of 16.9 mmHg. About 70 h after the block, this value decreased to a minimum level of 8.3 +/- 0.4 mmHg.

CONCLUSION

Decreasing pressure variation might indicate that lung growth has stopped and that the ideal point of time to remove the balloon is achieved. Increasing pressure has to be related to the morphometric analysis of the lung's structural development and maturation, comparing the efficacy of FETO in preventing or reversing pulmonary hypoplasia. Further investigation of continuous telemetric monitoring of tracheal pressure in the fetal lamb is required.

HARO7 encodes chorismate mutase of the methylotrophic yeast Hansenula polymorpha and is derepressed upon methanol utilization

The HARO7 gene of the methylotrophic, thermotolerant yeast Hansenula polymorpha was cloned by functional complementation. HARO7 encodes a monofunctional 280-amino-acid protein with chorismate mutase (EC 5.4. 99.5) activity that catalyzes the conversion of chorismate to prephenate, a key step in the biosynthesis of aromatic amino acids. The HARO7 gene product shows strong similarities to primary sequences of known eukaryotic chorismate mutase enzymes. After homologous overexpression and purification of the 32-kDa protein, its kinetic parameters (k(cat) = 319.1 s(-1), n(H) = 1.56, [S](0.5) = 16.7 mM) as well as its allosteric regulatory properties were determined. Tryptophan acts as heterotropic positive effector; tyrosine is a negative-acting, heterotropic feedback inhibitor of enzyme activity. The influence of temperature on catalytic turnover and the thermal stability of the enzyme were determined and compared to features of the chorismate mutase enzyme of Saccharomyces cerevisiae. Using the Cre-loxP recombination system, we constructed mutant strains carrying a disrupted HARO7 gene that showed tyrosine auxotrophy and severe growth defects. The amount of the 0.9-kb HARO7 mRNA is independent of amino acid starvation conditions but increases twofold in the presence of methanol as the sole carbon source, implying a catabolite repression system acting on HARO7 expression.

Water transport across yeast vacuolar and plasma membrane-targeted secretory vesicles occurs by passive diffusion

To determine whether solute transport across yeast membranes was facilitated, we measured the water and solute permeations of vacuole-derived and late secretory vesicles in Saccharomyces cerevisiae; all permeations were consistent with passive diffusive flow. We also overexpressed Fps1p, the putative glycerol facilitator in S. cerevisiae, in secretory vesicles but observed no effect on water, glycerol, formamide, or urea permeations. However, spheroplasts prepared from the strain overexpressing Fps1p showed enhanced glycerol uptake, suggesting that Fps1p becomes active only upon insertion in the plasma membrane.