Active radiation measurements over one solar cycle with two DOSTEL instruments in the Columbus laboratory of the International Space Station

Two DOSimetry TELescopes (DOSTELs) have been measuring the radiation environment in the Columbus module of the International Space Station (ISS) since 2009 in the frame of the DOSIS and DOSIS 3D projects. Both instruments have measured the charged particle flux rate and dose rates in a telescope geometry of two planar silicon detectors. The radiation environment in the ISS orbit is mostly composed by galactic cosmic radiation (GCR) and its secondary radiation and protons from the inner radiation belt in the South Atlantic Anomaly (SAA) with sporadic contributions of solar energetic particles at high latitudes. The data presented in this work cover two solar activity minima and corresponding GCR intensity maxima in 2009 and 2020 and the solar activity maximum and corresponding GCR intensity minimum in 2014/2015. Average dose rates measured in the Columbus laboratory in the ISS orbit from GCR and SAA are presented separately. The data is analyzed with respect to the effective magnetic shielding and grouped into different cut-off rigidity intervals. Using only measurements in magnetically unshielded regions at low cut-off rigidity and applying a factor for the geometrical shielding of the Earth, absorbed dose rates and dose equivalent rates in near-Earth interplanetary space are estimated for the years 2009 to 2022.

Experimental Analysis of Radiation Protection Offered by a Novel Exoskeleton-based Radiation Protection System Versus Conventional Lead Aprons

INTRODUCTION

The detrimental effects of radiation exposure to physicians have been well documented and are an active area of concern. The objective of this study was to evaluate the radiation protection offered by an exoskeleton-based radiation protection system (StemRad MD, StemRad Ltd, Israel).

METHODS

The experimental setup involved two anthropomorphic phantoms, an operator and a patient, and a C-arm as the X-ray radiation source. Thermo-luminescent detectors were used to measure radiation doses to different radiosensitive body parts on the operator phantom both with the StemRad MD and conventional lead apron (LA), at the left radial and right femoral positions. Detected radiation doses for the StemRad MD and LA for different body parts and positions were compared.

RESULTS

At the left radial position, mean radiation dose (mGy) reduction by the StemRad MD compared to the LA was above 90% for the left eye lens (0.22±0.13 vs 5.18±0.08, p<.0001), right eye lens (0.23±0.13 vs 4.98±0.10, p<.0001), left head (0.11±0.16 vs 3.53±0.07, p<.0001) , right head (0.27±0.09 vs 3.12±0.10, p<.0001), and left brain (0.04±0.08 vs 0.46±0.07, p<.0001). At the right femoral position, radiation reduction was above 90% for the left eye lens (0.14±0.10 vs 4.16±0.09, p<.0001), right eye lens (0.06±0.08 vs 1.90±0.11, p<.0001) , left head (0.10±0.08 vs 4.39±0.08, p<.0001), left brain (0.03±0.07 vs 1.44±0.08, p<.0001), right brain (0.00±0.14 vs 0.11±0.13, p=.06), and thyroid (0.04±0.07 vs 0.27±0.09, p<.0001).

CONCLUSIONS

The StemRad MD system provides superior radiation protection to the physician compared to conventional LAs. The effects are particularly impactful for the brain, eye lens, and head areas.

Levels of the cancer biomarker CA 19-9 are associated with thrombin generation in plasma from treatment-naïve pancreatic cancer patients

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is associated with a hypercoagulable state and high mortality. Increases in the plasma levels of tumor marker carbohydrate antigen (CA) 19-9 are used in diagnosis and follow-up but have also been reported to precede venous thromboembolism (VTE).

AIMS

We examined the association between CA 19-9 and thrombin generation (TG) in plasma from PDAC patients, as well as their association with coagulation biomarkers prior to pancreatic surgery. In addition, we determined the effect of commercial sources of CA 19-9 on TG.

METHODS

We collected plasma from 58 treatment-naïve PDAC patients without any signs of VTE. We measured levels of CA 19-9, FVIII, fibrinogen, D-dimer, antithrombin and extracellular vesicle (EV) tissue factor (TF) activity and TG using a Calibrated Automated Thrombogram (CAT). The effect of different commercial sources of CA 19-9 on TG in Standard Human Plasma (SHP) was also studied.

RESULTS

Patient plasma samples were divided into 4 preoperative groups based on the level of CA 19-9: none < 2, low = 3-200, high = 201-1000, and very high > 1000 U/mL. CA 19-9 levels were associated with several of the TG parameters, including endogenous thrombin potential, peak, and time to peak. CA 19-9 did not associate with any of the coagulation biomarkers. Spiking of SHP with CA 19-9 increased TG but this was decreased by an anti-TF antibody.

CONCLUSIONS

CA 19-9 was associated with TG in patients prior to any pancreatic cancer treatments or signs of VTE. Some commercial sources of CA 19-9 enhanced TG in SHP seemingly due to contaminating TF.

Questioning the radiation limits of life: Ignicoccus hospitalis between replication and VBNC

Radiation of ionizing or non-ionizing nature has harmful effects on cellular components like DNA as radiation can compromise its proper integrity. To cope with damages caused by external stimuli including radiation, within living cells, several fast and efficient repair mechanisms have evolved. Previous studies addressing organismic radiation tolerance have shown that radiotolerance is a predominant property among extremophilic microorganisms including (hyper-) thermophilic archaea. The analysis of the ionizing radiation tolerance of the chemolithoautotrophic, obligate anaerobic, hyperthermophilic Crenarchaeon Ignicoccus hospitalis showed a D₁₀-value of 4.7 kGy, fourfold exceeding the doses previously determined for other extremophilic archaea. The genome integrity of I. hospitalis after γ-ray exposure in relation to its survival was visualized by RAPD and qPCR. Furthermore, the discrimination between reproduction, and ongoing metabolic activity was possible for the first time indicating that a potential viable but non-culturable (VBNC) state may also account for I. hospitalis.

The German Aerospace Center M-42 radiation detector-A new development for applications in mixed radiation fields

In the last few years, the Biophysics Working Group of the Institute of Aerospace Medicine of the German Aerospace Center (DLR) started the development of a small low power consumption radiation detector system for the measurement of the absorbed dose to be applied in various environments, such as onboard aircraft, in space, and also as a demonstration tool for students. These so called DLR M-42 detectors are based on an electronics design, which can easily be adjusted to the user- and mission-requirements. M-42 systems were already applied for measurements in airplanes, during two MAPHEUS (Materialphysikalische Experimente unter Schwerelosigkeit) rocket missions, and are currently prepared for long term balloon experiments. In addition, they will be part of the dosimetry suite of the upcoming Matroshka AstroRad Radiation Experiment on the NASA Artemis I mission. This paper gives an overview of the design and the testing of the DLR M-42 systems and provides highlighted results from the MAPHEUS campaigns where the detectors were tested for the first time under space flight conditions. Results clearly show that the system design enables independent measurements starting upon rocket launch due to the built-in accelerometer sensors and provides data for the relevant 6 min of μ-gravity as given for the MAPHEUS missions. These 6 min of the μ-gravity environment at altitudes between 100 and 240 km lead to a total absorbed dose of 1.21 ± 0.15 µGy being equivalent to half a day of radiation background measured with the M-42 in the laboratory at DLR, Cologne, Germany.

Photochemistry on the Space Station-Antibody Resistance to Space Conditions after Exposure Outside the International Space Station

Antibody-based analytical instruments are under development to detect signatures of life on planetary bodies. Antibodies are molecular recognition reagents able to detect their target at sub-nanomolar concentrations, with high affinity and specificity. Studying antibody binding performances under space conditions is mandatory to convince space agencies of the adequacy of this promising tool for planetary exploration. To complement previous ground-based experiments on antibody resistance to simulated irradiation, we evaluate in this paper the effects of antibody exposure to real space conditions during the EXPOSE-R2 mission outside the International Space Station. The absorbed dose of ionizing radiation recorded during the 588 days of this mission (220 mGy) corresponded to the absorbed dose expected during a mission to Mars. Moreover, samples faced, at the same time as irradiation, thermal cycles, launch constraints, and long-term storage. A model biochip was used in this study with antibodies in freeze-dried form and under two formats: free or covalently grafted to a solid surface. We found that antibody-binding performances were not significantly affected by cosmic radiation, and more than 40% of the exposed antibody, independent of its format, was still functional during all this experiment. We conclude that antibody-based instruments are well suited for in situ analysis on planetary bodies.

Photochemistry on the Space Station-Aptamer Resistance to Space Conditions: Particles Exposure from Irradiation Facilities and Real Exposure Outside the International Space Station

Some microarray-based instruments that use bioaffinity receptors such as antibodies or aptamers are under development to detect signatures of past or present life on planetary bodies. Studying the resistance of such instruments against space constraints and cosmic rays in particular is a prerequisite. We used several ground-based facilities to study the resistance of aptamers to various types of particles (protons, electrons, neutrons, and carbon ions) at different energies and fluences. We also tested the resistance of aptamers during the EXPOSE-R2 mission outside the International Space Station (ISS). The accumulated dose measured after the 588 days of this mission (220 mGy) corresponds to the accumulated dose that can be expected during a mission to Mars. We found that the recognition ability of fluorescently labeled aptamers was not significantly affected during short-term exposure experiments taking into account only one type of radiation at a time. However, we demonstrated that the same fluorescent dye was significantly affected by temperature variations (-21°C to +58°C) and storage throughout the entirety of the ISS experiment (60% of signal loss). This induced a large variability of aptamer signal in our analysis. However, we found that >50% of aptamers were still functional after the whole EXPOSE-R2 mission. We conclude that aptamer-based instruments are well suited for in situ analysis on planetary bodies, but the detection step requires additional investigations.

Activation of plasmacytoid dendritic cells by apoptotic particles - mechanism for the loss of immunological tolerance in Sjögren's syndrome

Sjögren's syndrome (SS) is a common autoimmune disease targeting salivary and lacrimal glands. It is strongly female-dominant, characterized by low oestrogen levels combined with a local intracrine dihydrotestosterone defect. We hypothesized that these hormonal deficits lead to increased apoptosis of the epithelial cells and plasmacytoid dendritic cell (pDC)-mediated proinflammatory host responses. Expression of Toll-like receptors (TLRs)-7 and -9 and cytokine profiles was studied in pDCs treated with apoptotic particles collected in consecutive centrifugation steps of media from apoptotic cells. Expression and localization of SS autoantigens in these particles was also analysed. Furthermore, the effects of sex steroids were studied in pDCs cultured with several concentrations of dihydrotestosterone and 17-β-oestradiol, and in saliva of patient treated with dehydroepiandrosterone. Apoptosis of the epithelial cells led to cleavage and translocation of SS-autoantigens, α-fodrin and SS-A, into apoptotic particles. The apoptosis-induced apoptotic particles also contained another SS-autoantigen, hy1-RNA. These particles were internalized by pDCs in a size-dependent manner and affected TLR-7 and -9 expression and the production of proinflammatory cytokines. The analysed androgens protected cells from apoptosis, influenced redistribution of autoantigens and diminished the apoptotic particle-stimulated increase of the TLRs in pDCs. Our findings suggest that the formation of apoptotic particles may play a role in loss of immune tolerance, manifested by production of autoantibodies and the onset of autoinflammation in SS.

High-energy proton imaging for biomedical applications

The charged particle community is looking for techniques exploiting proton interactions instead of X-ray absorption for creating images of human tissue. Due to multiple Coulomb scattering inside the measured object it has shown to be highly non-trivial to achieve sufficient spatial resolution. We present imaging of biological tissue with a proton microscope. This device relies on magnetic optics, distinguishing it from most published proton imaging methods. For these methods reducing the data acquisition time to a clinically acceptable level has turned out to be challenging. In a proton microscope, data acquisition and processing are much simpler. This device even allows imaging in real time. The primary medical application will be image guidance in proton radiosurgery. Proton images demonstrating the potential for this application are presented. Tomographic reconstructions are included to raise awareness of the possibility of high-resolution proton tomography using magneto-optics.

Space experiment "Cellular Responses to Radiation in Space (CellRad)": Hardware and biological system tests

One factor contributing to the high uncertainty in radiation risk assessment for long-term space missions is the insufficient knowledge about possible interactions of radiation with other spaceflight environmental factors. Such factors, e.g. microgravity, have to be considered as possibly additive or even synergistic factors in cancerogenesis. Regarding the effects of microgravity on signal transduction, it cannot be excluded that microgravity alters the cellular response to cosmic radiation, which comprises a complex network of signaling pathways. The purpose of the experiment "Cellular Responses to Radiation in Space" (CellRad, formerly CERASP) is to study the effects of combined exposure to microgravity, radiation and general space flight conditions on mammalian cells, in particular Human Embryonic Kidney (HEK) cells that are stably transfected with different plasmids allowing monitoring of proliferation and the Nuclear Factor κB (NF-κB) pathway by means of fluorescent proteins. The cells will be seeded on ground in multiwell plate units (MPUs), transported to the ISS, and irradiated by an artificial radiation source after an adaptation period at 0 × g and 1 × g. After different incubation periods, the cells will be fixed by pumping a formaldehyde solution into the MPUs. Ground control samples will be treated in the same way. For implementation of CellRad in the Biolab on the International Space Station (ISS), tests of the hardware and the biological systems were performed. The sequence of different steps in MPU fabrication (cutting, drilling, cleaning, growth surface coating, and sterilization) was optimized in order to reach full biocompatibility. Different coatings of the foil used as growth surface revealed that coating with 0.1 mg/ml poly-D-lysine supports cell attachment better than collagen type I. The tests of prototype hardware (Science Model) proved its full functionality for automated medium change, irradiation and fixation of cells. Exposure of HEK cells to the β-rays emitted by the radiation source dose-dependently decreased cell growth and increased NF-κB activation. The signal of the fluorescent proteins after formaldehyde fixation was stable for at least six months after fixation, allowing storage of the MPUs after fixation for several months before the transport back to Earth and evaluation of the fluorescence intensity. In conclusion, these tests show the feasibility of CellRad on the ISS with the currently available transport mechanisms.

Diminished salivary epidermal growth factor secretion: a link between Sjögren's syndrome and autoimmune gastritis?

OBJECTIVES

Healthy human labial salivary glands produce epidermal growth factor (EGF). In Sjögren's syndrome (SS), EGF staining is diminished. SS is also associated with chronic autoimmune corpus gastritis. We therefore hypothesized that EGF secretion would be diminished in SS and that this could affect gastric target cells.

METHODS

Salivary EGF secretion in SS was compared to that in healthy controls using an enzyme-linked immunosorbent assay (ELISA). EGF receptor (EGFR) immunoreactive cells in the gastric corpus of healthy human subjects were analysed using immunostaining.

RESULTS

Salivary secretion of EGF was diminished in SS patients (232.4, range 52.6-618.4, vs. 756.6, range 105.3-1631.6 pg/min, p = 0.002). Proton-pump positive parietal cells were mostly EGFR immunoreactive whereas very few pepsinogen I (PGI)-positive cells were EGFR positive.

CONCLUSIONS

As EGF is relatively acid resistant, salivary gland-derived EGF might participate in an exo/endocrine mode of parietal cell maintenance in the gastric corpus. Deficiency of salivary gland-derived EGF in SS patients may cause impairment of gastric parietal cells resulting in exposure of immunogenic cryptic antigens and loss of immunological self-tolerance.

Dermatoglyphic variation and weight and length at birth

Relationships between dermatoglyphic variables, including finger ridge counts and finger, palmar, and plantar pattern intensities, and weight and length at birth, were tested in a sample of 184 boys and 202 girls from Warsaw schools. No convincing evidence for such relationships has been obtained from the results of correlations and one-way analysis of variance, although there are indications that some palmar traits may be related to length at birth in females. The data agree with the common belief that birth weight and birth length are mainly determined by influences operating in later stages of pregnancy, that is, after the 20th gestational week.