The effects of solar radiation and nutrient solution temperature on the uptake of oxygen by submerged roots of mature tomato plants

Summary A statistical analysis of data on oxygen uptake by submerged roots of mature tomato plants, from a nutrient solution containing sufficient oxygen, has demonstrated that variations in oxygen uptake are positively related to variations in solar radiaton, particularly at radiation levels below 2.0 MegaJoules.h⁻¹.m⁻². Above this level, however, anegative relationship is indicated, suggesting that intense solar radiation reduces the ability of plant roots to obtain sufficient oxygen for optimum growth processes. It also appears that there is atime lag of about one to two hours between the effects of solar radiation on oxygen uptake. Greenhouse air temperature is positively correlated with radiation, with little or no time lag, and variations in greenhouse air temperature effect variations in solution temperature with a time lag of 2 to 3 hours. Greenhouse air temperature affects respiration in the submerged roots indirectly, with a 1 to 2 hour lag, by effecting the nutrient solution temperature, and possibly by affecting the growth processes in thesubaerial roots, which in turn may result, in some way, in increased oxygen uptake by the submerged roots, partly bypassing the restraining effects of lagging nutrient solution temperature. Variations in nutrient solution temperature do not appear to be causally related in effecting variations in oxygen uptake in a major way, probably because a considerable time lag of around 3 hours seems to exist between variations in radiation and solution temperature, in this experiment. As such, radiation and greenhouse air temperature appear to be rather important and dominant variables, effecting changes in oxygen uptake. In addition, the results suggest thatdaytime, variable heating of the nutrient solution, in step with the variations of solar radiation, as well as shading of the tomato crop under conditions of intense solar radiation would likely be beneficial for plant growth and crop production.     

Lithuanian cohort of Chernobyl cleanup workers: Cancer incidence follow-up 1986–2012

BackgroundCancer risks following radiation exposure in adulthood after Chernobyl are less studied compared to those after exposure in childhood. We aimed to evaluate cancer risk in the Lithuanian cohort of Chernobyl cleanup workers 26 years after their exposure in Chernobyl.MethodsStudy population (6707 men) was followed for cancer incidence upon return from Chernobyl till the end of 2012 by linkage procedure with the Lithuanian Cancer Registry and for migration and death – with Central Population Registry. The site-specific cancer risk in the cohort was estimated by calculating the standardised incidence ratio (SIR) with 95 % confidence interval (CI).ResultsA total of 596 cancer cases was observed in the cohort, against 584 expected (SIR 1.02; 95 % CI 0.94, 1.11). Only incidence of mouth and pharynx cancers was increased compared to the expected (SIR 1.41; 95 % CI 1.07, 1.86). Nevertheless, an increased risk of thyroid cancer was observed among cleanup workers who were younger than 30 years when entering the Chernobyl zone (SIR 2.90; 95 % CI 1.09, 7.72), whose radiation dose was above 100 milisievert (mSv) (SIR 3.13; 95 % CI 1.30, 7.52) and who had shorter duration of stay (SIR 2.30; 95 % CI 1.03, 5.13).ConclusionsOur findings are consistent with those observed in other cohorts of workers, namely, the increased risk of cancer sites related to behavioural factors. The increased risk of thyroid cancer among cleanup workers who were younger than 30 years when entering Chernobyl and whose radiation dose was above 100 mSv cannot exclude the association with the radiation exposure in Chernobyl.     

Bacterial Pleckstrin Homology Domains: A Prokaryotic Origin for the PH Domain

Pleckstrin homology (PH) domains have been identified only in eukaryotic proteins to date. We have determined crystal structures for three members of an uncharacterized protein family (Pfam PF08000), which provide compelling evidence for the existence of PH-like domains in bacteria (PHb). The first two structures contain a single PHb domain that forms a dome-shaped, oligomeric ring with C₅ symmetry. The third structure has an additional helical hairpin attached at the C-terminus and forms a similar but much larger ring with C₁₂ symmetry. Thus, both molecular assemblies exhibit rare, higher-order, cyclic symmetry but preserve a similar arrangement of their PHb domains, which gives rise to a conserved hydrophilic surface at the intersection of the β-strands of adjacent protomers that likely mediates protein-protein interactions. As a result of these structures, additional families of PHb domains were identified, suggesting that PH domains are much more widespread than originally anticipated. Thus, rather than being a eukaryotic innovation, the PH domain superfamily appears to have existed before prokaryotes and eukaryotes diverged.     

A review on gold nanoparticles radiosensitization effect in radiation therapy of cancer

In the recent years, application of nanoparticles in diagnosis and treatment of cancer has been the issue of extensive research. Among these studies some have focused on the dose enhancement effect of gold nanoparticles (GNPs) in radiation therapy of cancer. On the other hand, some studies indicated energy dependency of dose enhancement effect, and the others have studied the GNP size effect in association with photon energy. However, in some aspects of GNP-based radiotherapy the results of recent studies do not seem very conclusive in spite of relative agreement on the basic physical interaction of photoelectric between GNPs and low energy photons. The main idea behind the GNP dose enhancement in some studies is not able to explain the results especially in recent investigation on cell lines and animal models radiation therapy using GNPs. In the present article the results of the available reports and articles were analyzed and compared and the final status of the GNP-RT was discussed.     

Increased radiation toxicity with germline ATM variant of uncertain clinical significance

BackgroundWhile patients with ataxia telangiectasia are known to have increased radiation sensitivity, patients with germline heterozygous ataxia telangiectasia mutated (ATM) mutations can have widely varying functional and clinical effects, which can make management decisions difficult. With an increased prevalence of gene panel-based testing for breast cancer patients, radiation oncologists are increasingly confronted with patients who carry germline ATM variants of uncertain clinical significance. This study describes the clinical courses and outcomes of 5 breast cancer patients with varying germline heterozygous ATM mutations undergoing radiation therapy at our institution in order to provide additional knowledge of the varying clinical effects to aid future decision making.Case SeriesWe identified 5 patients with breast cancer and varying germline heterozygous ATM mutations treated at the University of North Carolina Hospitals between 2015 and 2017. The median age at breast cancer diagnosis for the patient series was 46. Clinical effects of radiation treatment varied amongst the 5 patients. The one patient with a pathogenic ATM mutation had no increased radiation related toxicity. Of the 4 patients with ATM variants of uncertain significance, one patient had increased radiation sensitivity with Grade 3 dermatitis. All patients have remained recurrence free with a median duration of 18 months.ConclusionOur data illustrates that patients with germline heterozygous ATM mutations can have widely varying clinical effects with radiation therapy. Given the possibility of unpredictable deleterious effects, our study highlights the importance of caution and careful consideration when devising the multi-modality management strategy in these patients.     

Predicting the required thickness of custom shielding materials in kilovoltage radiotherapy beams

The planning and delivery of kilovoltage (kV) radiotherapy treatments involves the use of custom shielding designed and fabricated for each patient. This study investigated methods by which the required thickness of custom shielding could be predicted for non-standard shielding materials fabricated using 3D printing techniques. Seven kV radiation beams from a WOmed T-300 X-ray therapy unit were modelled using SpekPy software, and AAPM TG-61 data were used to account for backscatter and spectral effects, for incrementally increasing thicknesses of Pb, W-PLA composite and Cu-PLA composite materials. The same beams were used to perform physical transmission measurements, and the thickness of each material required to achieve 5% beam transmission was determined. While the measured transmission factors for Pb, W-PLA and Cu-PLA shielding generally exceeded the calculated transmission factors, these differences had minimal effect on the derived thicknesses of shielding required to achieve 5% transmission, where calculations agreed with measurements within 0.5 mm for Pb at all available energies (70–300 kVp), within 1.4 mm for W-PLA at all available energies, and within 2.1 mm for Cu-PLA at superficial treatment energies (70–100 kVp). The incremental transmission factor calculation method described and validated in this study could be used, in combination with the conservative addition of 1–2 mm of additional material, to estimate shielding requirements for novel materials in therapeutic kilovoltage beams. However, if calculated shielding thicknesses equate to 10 mm or more, then additional verification measurements should be performed and the clinical suitability of the novel shielding material should be re-evaluated.     

Analysis of pre-residency research productivity,dual degree status,and gender distribution of underrepresented minorities among a current United States radiation oncology junior resident class

BackgroundAmong the most competitive medical subspecialties, representation of underrepresented minorities (African–American race and/or Hispanic ethnicity) among resident trainees has historically been low compared to their United States Census general population representation. Research productivity and dual degree status may impact residency applicant competitiveness. To date, such an analysis has yet to be performed in Radiation Oncology.MethodsA list of radiation oncology residents from the graduating class of 2022 was obtained through internet searches. Demographics included were gender and dual degree status. Research productivity was calculated using the number of pre-residency peer-reviewed publications (PRP). Fisher's exact test was used for statistical analysis.ResultsOf the 179 residents evaluated from the 2022 class, eleven (6.1%) were underrepresented minorities. Compared to the remainder of the class, underrepresented minorities had a lower proportion of men (63.6% versus 69.3%), a higher proportion of dual degrees (45.5% versus 28.6%), and a lower proportion of MD-PhD degrees (9.1% versus 17.2%). Underrepresented minorities had a higher proportion of residents with at least two PRP (72.7% versus 57.1%) and a lower proportion of residents with no PRP (18.2% versus 24.4%). None of these differences reached statistical significance (p > 0.05).ConclusionUnderrepresented minorities were comparable to the remainder of their Radiation Oncology resident class regarding gender distribution, dual degrees status, and likelihood of having at least two peer-reviewed publications cited in PubMed during the calendar year of residency application. Further studies will be needed to determine how these findings translate into future scholarly activity and post-graduate career choice.     

Relevance of body size and shell colouration for thermal absorption and heat loss in white garden snails,Theba pisana (Helicidae), from Northern France

The internal temperature of land snails depends on environmental factors, such as exposure to electromagnetic radiation and airflow as well as biotic factors including shell size, shell colouration and thickness or the resting position of the snail. In controlled field experiments, we quantified heating by thermal absorption of light and airflow-induced heat loss in the white garden snail, Theba pisana, from Normandy, France. Heating experiments revealed a significant positive relation of the internal body temperature with illumination period, shell temperature and air temperature at different times of day. The size of the snails was negatively related with both of the given illumination times: smaller animals heated up stronger than larger ones. The temperature at the surface of the shell significantly depended on the illumination period and the time of day. An AIC-based quality assessment of multiple linear modelling showed that, for explaining both shell surface and internal temperature of the soft body, several factors, i.e., exposure time, daytime, shell size and colouration contributed to the best models, respectively. Similarly, heat loss of the soft body after and during exposure of the snails to sunlight by a constant airflow depended on the initial body temperature, shell size, colouration and ambient air temperature. Our study revealed also the importance of both shell size and colouration for the loss of body temperature under natural conditions: small and banded animals that had heated up to temperatures above 30 °C cooled down faster than large and un-banded ones.     

Patient dose monitoring systems: A new way of managing patient dose and quality in the radiology department

PurposeDue to the upcoming European Directive (2013/59/EURATOM) and the increased focus on patient safety in international guidelines and regulations, Patient Dose Monitoring Systems, also called Dose Management Systems (DMS), are introduced in medical imaging departments. This article focusses on the requirements for a DMS, its benefits and the necessary implementation steps.MethodThe implementation of a DMS can be perceived as a lengthy, yet worthy, procedure: users have to select the appropriate system for their applications, prepare data collection, validate, perform configuration, and start using the results in quality improvement projects.ResultsA state of the art DMS improves the quality of service, ensures patient safety and optimizes the efficiency of the department. The gain is multifaceted: the initial goal is compliance monitoring against diagnostic reference levels. At a higher level, the user gets an overview of the performance of the devices or centers that are under his supervision. Error identification, generation of alerts and workflow analysis are additional benefits. It can also enable a more patient-centric approach with personalized dosimetry. Skin dose, size-specific dose estimates and organ doses can be calculated and evaluated per patient.ConclusionA DMS is a powerful tool and essential for improved quality and patient care in a radiology department. It can be configured to the needs of medical physicists, radiologists, technologists, even for the management of the hospital. Collaboration between all health professionals and stakeholders, input-output validation and communication of findings are key points in the process of a DMS implementation.