Dosimetric impact of rectum and bladder anatomy and intrafractional prostate motion on hypofractionated prostate radiation therapy

OBJECTIVE

The objective of this study was to evaluate the dosimetric impact on hypofractionated prostate radiation therapy of two geometric uncertainty sources: rectum and bladder filling and intrafractional prostate motion.

MATERIALS AND METHODS

This prospective study included 544 images (375 pre-treatment cone-beam CT [CBCT] and 169 post-treatment CBCT) from 15 prostate adenocarcinoma patients. We recalculated the dose on each pre-treatment CBCT once the positioning errors were corrected. We also recalculated two dose distributions on each post-treatment CBCT, either using or not intrafractional motion correction. A correlation analysis was performed between CBCT-based dose and rectum and bladder filling as well as intrafraction prostate displacements.

RESULTS

No significant differences were found between administered and planned rectal doses. However, we observed an increase in bladder dose due to a lower bladder filling in 66% of treatment fractions. These differences were reduced at the end of the fraction since the lower bladder volume was compensated by the filling during the treatment session. A statistically significant reduction in target volume coverage was observed in 27% of treatment sessions and was correlated with intrafractional prostate motion in sagittal plane > 4 mm.

CONCLUSIONS

A better control of bladder filling is recommended to minimize the number of fractions in which the bladder volume is lower than planned. Fiducial mark tracking with a displacement threshold of 5 mm in any direction is recommended to ensure that the prescribed dose criteria are met.

Global Polarization of Ξ and Ω Hyperons in Au+Au Collisions at sqrt[s_{NN}]=200 GeV

Global polarization of Ξ and Ω hyperons has been measured for the first time in Au+Au collisions at sqrt[s_{NN}]=200  GeV. The measurements of the Ξ^{-} and Ξ[over ¯]^{+} hyperon polarization have been performed by two independent methods, via analysis of the angular distribution of the daughter particles in the parity violating weak decay Ξ→Λ+π, as well as by measuring the polarization of the daughter Λ hyperon, polarized via polarization transfer from its parent. The polarization, obtained by combining the results from the two methods and averaged over Ξ^{-} and Ξ[over ¯]^{+}, is measured to be ⟨P_{Ξ}⟩=0.47±0.10(stat)±0.23(syst)% for the collision centrality 20%-80%. The ⟨P_{Ξ}⟩ is found to be slightly larger than the inclusive Λ polarization and in reasonable agreement with a multiphase transport model. The ⟨P_{Ξ}⟩ is found to follow the centrality dependence of the vorticity predicted in the model, increasing toward more peripheral collisions. The global polarization of Ω, ⟨P_{Ω}⟩=1.11±0.87(stat)±1.97(syst)% was obtained by measuring the polarization of daughter Λ in the decay Ω→Λ+K, assuming the polarization transfer factor C_{ΩΛ}=1.

Distance to native climatic niche margins explains establishment success of alien mammals

One key hypothesis explaining the fate of exotic species introductions posits that the establishment of a self-sustaining population in the invaded range can only succeed within conditions matching the native climatic niche. Yet, this hypothesis remains untested for individual release events. Using a dataset of 979 introductions of 173 mammal species worldwide, we show that climate-matching to the realized native climatic niche, measured by a new Niche Margin Index (NMI), is a stronger predictor of establishment success than most previously tested life-history attributes and historical factors. Contrary to traditional climatic suitability metrics derived from species distribution models, NMI is based on niche margins and provides a measure of how distant a site is inside or, importantly, outside the niche. Besides many applications in research in ecology and evolution, NMI as a measure of native climatic niche-matching in risk assessments could improve efforts to prevent invasions and avoid costly eradications.

Application of discrete cosine transform to assess the effect of tumor motion variations on the definition of ITV in lung and liver SBRT

PURPOSE

To use Discrete Cosine Transform to include tumor motion variations on ITV definition of SBRT patients.

METHODS

Data from 66 patients was collected. 2D planar fluoroscopy images (FI) were available for 54 patients. Daily CBCT projections (CBCTp) from 29 patients were employed to measure interfraction amplitude variability. Systematic amplitude variations were obtained from 17 patients with data from both FI and CBCTp. Tumor motion curves obtained from FI were characterized with a Cosine model (CM), based on cosine functions to the power of 2, 4 or 6, and DCT. Performance of both models was evaluated by means of R² coefficient and by comparing their results on Internal Target Volume (ITV) margins against those calculated from original tumor motion curves. Amplitude variations from CBCTp, as well as estimations of baseline shift variations were added to the DCT model to account for their effect on ITV margins.

RESULTS

DCT replicated tumor motion curves with a mean R² values for all patients of 0.86, 0.91 and 0.96 for the lateral (LAT), anterior-posterior (AP) and cranio-caudal (CC) directions respectively. CM yielded worst results, with R² values of 0.64, 0.61 and 0.74 in the three directions. Interfraction amplitude variation increased ITV margins by a 9%, while baseline shift variability implied a 40% and 80-100% increase for normalized values of baseline shift of 0.2 and 0.4 respectively.

CONCLUSIONS

Probability distribution functions of tumor positions can be successfully characterized with DCT. This permits to include tumor motion variablilities obtained from patient population into patient specific ITVs.

Nonmonotonic Energy Dependence of Net-Proton Number Fluctuations

Nonmonotonic variation with collision energy (sqrt[s_{NN}]) of the moments of the net-baryon number distribution in heavy-ion collisions, related to the correlation length and the susceptibilities of the system, is suggested as a signature for the quantum chromodynamics critical point. We report the first evidence of a nonmonotonic variation in the kurtosis times variance of the net-proton number (proxy for net-baryon number) distribution as a function of sqrt[s_{NN}] with 3.1  σ significance for head-on (central) gold-on-gold (Au+Au) collisions measured solenoidal tracker at Relativistic Heavy Ion Collider. Data in noncentral Au+Au collisions and models of heavy-ion collisions without a critical point show a monotonic variation as a function of sqrt[s_{NN}].

Are artificial intelligence systems useful in breast cancer screening programs?

Population-based breast cancer screening programs are efficacious in reducing the mortality due to breast cancer. These programs use mammography to screen the women who are invited to participate. Digital mammography makes it possible to develop computer-assisted diagnosis (CAD) systems that promise to reduce the workload of radiologists participating in screening programs. However, various studies have shown that CAD results in a high rate of false positive diagnoses. Systems based on artificial intelligence are being more widely implemented, and studies have shown that these systems have better diagnostic performance than traditional CAD systems. This article explains the fundamentals of artificial intelligence systems and an overview of possible applications of these systems within the framework of breast cancer screening programs.

Efficacy of a live intranasal vaccine against parainfluenza type 3 and bovine respiratory syncytial virus in young calves with maternally derived antibodies

Trial design

Two randomised controlled vaccination trials with artificial challenges were carried out in addition to a serological survey of levels of maternally derived antibodies (MDA) to parainfluenza type 3 virus (PI3V) and bovine respiratory syncytial virus (BRSV) in European calves.

Participants

Ten-day-old calves with and without MDA were included in the two vaccine trials.

Interventions

Intranasal administration of a bivalent modified live (PI3V/BRSV) vaccine followed by artificial challenge approximately three months post vaccination.

Objective

The study aimed to assess the efficacy of a modified live respiratory vaccine, Bovalto Respi Intranasal (Boehringer Ingelheim). In order to assess the interference of MDA, both seropositive and seronegative calves were used.

Randomisation

PI3V and BRSV serological status was determined seven days before vaccination; calves without maternal antibodies became the MDA− vaccinates. Calves with MDA were ranked according to individual titres and allocated alternately to MDA+ vaccinate and MDA+ control groups.

Blinding

Treatment was carried out by the unblinded study director. Animal care and veterinary examinations were conducted by personnel unaware of the treatments received. The serological survey used blood samples obtained from calves on commercial farms in five European countries, Germany, Spain, Italy, Ireland and the UK, to determine the levels of MDA to PI3V and BRSV in calves approximately two weeks of age.

Results

A total of 36 calves were included in the two challenge studies and 32 of these completed the challenge studies. Twenty-one calves were included in the PI3V challenge study, with six of six MDA− and six of seven MDA+ vaccinated calves and five of five MDA+ unvaccinated control calves being challenged with PI3V. Fifteen calves were included in the BRSV challenge study, with five of five MDA− and five of five MDA+ vaccinated calves and five of five MDA+ unvaccinated control calves being challenged with BRSV.

Outcome

For both challenges, clinical scores and nasal shedding were significantly higher in control animals compared with vaccinates (PI3V challenge: clinical scores P=0.001, nasal shedding P=0.001; BRSV challenge: clinical scores P=0.016, nasal shedding P=0.002) and not significantly different between MDA+ and MDA− vaccinated animals for both challenges (P>0.05). A total of 254 samples from six countries were tested in the serological survey of MDA.

Conclusion

The results of the challenge studies demonstrated the efficacy of the vaccine in the presence of BRSV and PI3V MDA under laboratory conditions. The field assessment confirmed that the MDA titres in the MDA+ calves corresponded to those typically found on farms.

Matrix Isolation Spectroscopy and Nuclear Spin Conversion of Propyne Suspended in Solid Parahydrogen

Parahydrogen (pH₂) quantum solids are excellent matrix isolation hosts for studying the rovibrational dynamics and nuclear spin conversion (NSC) kinetics of molecules containing indistinguishable nuclei with nonzero spin. The relatively slow NSC kinetics of propyne (CH₃CCH) isolated in solid pH₂ is employed as a tool to assign the rovibrational spectrum of propyne in the 600-7000 cm^-1 region. Detailed analyses of a variety of parallel (ΔK = 0) and perpendicular (ΔK=±1) bands of propyne indicate that the end-over-end rotation of propyne is quenched, but K rotation of the methyl group around the C₃ symmetry axis still persists. However, this single-axis K rotation is significantly hindered for propyne trapped in solid pH₂ such that the energies of the K rotational states do not obey simple energy-level expressions. The NSC kinetics of propyne follows first-order reversible kinetics with a 287(7) min effective time constant at 1.7 K. Intensity-intensity correlation plots are used to determine the relative line strengths of individual ortho- and para-propyne rovibrational transitions, enabling an independent estimation of the ground vibrational state effective A″ constant of propyne.

First Measurement of Λ_{c} Baryon Production in Au+Au Collisions at sqrt[s_{NN}]=200 GeV

We report on the first measurement of the charmed baryon Λ_{c}^{±} production at midrapidity (|y|<1) in Au+Au collisions at sqrt[s_{NN}]=200  GeV collected by the STAR experiment at the Relativistic Heavy Ion Collider. The Λ_{c}/D^{0} [denoting (Λ_{c}^{+}+Λ_{c}^{-})/(D^{0}+D[over ¯]^{0})] yield ratio is measured to be 1.08±0.16  (stat)±0.26  (sys) in the 0%-20% most central Au+Au collisions for the transverse momentum (p_{T}) range 3<p_{T}<6  GeV/c. This is significantly larger than the pythia model calculations for p+p collisions. The measured Λ_{c}/D^{0} ratio, as a function of p_{T} and collision centrality, is comparable to the baryon-to-meson ratios for light and strange hadrons in Au+Au collisions. Model calculations including coalescence hadronization for charmed baryon and meson formation reproduce the features of our measured Λ_{c}/D^{0} ratio.

Alteration of Bumblebee Venom Composition toward Higher Elevation

Venomous animals use venom, a complex biofluid composed of unique mixtures of proteins and peptides, for either predation or defense. Bumblebees, which occur in various habitats due to their unique thermoregulatory properties, mainly use venom for defense. Herein, we conducted an exploratory analysis of the venom composition of a bumblebee species (Bombus pascuorum) along an elevation gradient in the western Swiss Alps using shot-gun proteomic approaches to assess whether their defense mechanism varies along the gradient. The gradient was characterized by high temperatures and low humidity at low elevations and low temperatures and high humidity at high elevations. Venom composition is changing along the elevation gradient, with proteomic variation in the abundances of pain-inducing and allergenic proteins. In particular, the abundance of phospholipase A₂-like, the main component of bumblebee venom, gradually decreases toward higher elevation (lower temperature), suggesting venom alteration and thus a decrease in bumblebee defense towards harsher environments. Larger datasets may complement this study to validate the observed novel trends.

Inhibition of adhesion-specific genes by Solidago virgaurea extract causes loss of Candida albicans biofilm integrity

AIMS

Candida albicans biofilms are commonly associated with severe oral infections. We previously discovered that a crude extract from the Solidago virgaurea plant (SV extract) was a potent inhibitor of C. albicans biofilm formation. Here, we further investigate the mechanisms underlying C. albicans biofilm inhibition by the SV extract.

METHODS AND RESULTS

The SV extract was shown to inhibit laboratory and clinical C. albicans isolates adherence and hyphal transition on inert support and epithelial human cells, without affecting viability and growth of planktonic yeasts. Interestingly, RT-PCR-based experiments demonstrated that some key genes involved in adhesion and hyphal morphological switch (e.g. Hwp1p, Ece1p, Als3p) were strongly down-regulated by the SV extract. Moreover, antimicrobial synergy testing (checkerboard assay) demonstrated that antifungal effects of miconazole, nystatin or a common antiseptic mouthwash were synergistically improved when used in combination with the SV extract.

CONCLUSIONS

The SV extract prevents C. albicans biofilm formation through direct inhibition of key adherence and hyphae-associated genes.

SIGNIFICANCE AND IMPACT OF THE STUDY

Biofilm is considered as a key virulence factor of C. albicans infection. Our discovery of an inhibitor specifically acting on genes involved in biofilm formation paves the way for the future development of a new class of antifungal product.

New measures for evaluation of environmental perturbations using Before-After-Control-Impact analyses

Before-After-Control-Impact (BACI) designs are powerful tools to derive inferences about environmental perturbations (e.g., hurricanes, restoration programs) when controlled experimental designs are unfeasible. Applications of BACI designs mostly rely on testing for a significant interaction between periods and treatments (so-called BACI contrast) to demonstrate the effects of the perturbation. However, significant interactions can emerge for several reasons, including when changes are larger in control sites, such that additional diagnostics must be performed to determine the full complexity of system changes. We propose two measures that detail the nature of change implied by BACI contrasts, along with its uncertainty. CI-divergence (Control-Impact divergence) quantifies to what extent control and impact sites have diverged between the after and the before period, whereas CI-contribution (Control-Impact contribution) quantifies to what extent the change between periods is stronger in impact sites relative to control sites. To illustrate how these two CI measures can be combined with BACI contrast to gain insights about effects of environmental perturbations, we used count data from the Swedish Breeding Bird Survey to investigate how hurricane Gudrun affected the long-term abundances of four bird species in forested areas of southern Sweden. Before-After-Control-Impact contrasts suggested the hurricane affected all four species. However, the values of the two CI measures strongly differed, even among species showing similar BACI contrasts. Those differences highlight qualitatively distinct population trajectories between periods and treatments requiring different ecological explanations. Overall, we show that BACI contrasts do not provide the full story in assessing the effects of environmental perturbations. The two CI measures can be used to assist ecological interpretations, or to specify detailed hypotheses about effects of restoration actions to allow stronger confirmatory inference about their outcomes. By providing a framework to develop more detailed explanations and hypotheses about ecological changes, the two CI measures can improve conclusions and strengthen evidence of effects of conservation actions and impact assessments under BACI designs.

Global assessment of early warning signs that temperature could undergo regime shifts

Climate change metrics have been used to quantify the exposure of geographic areas to different facets of change and relate these facets to different threats and opportunities for biodiversity at a global scale. In parallel, a suite of indicators have been developed to detect approaching transitions between alternative stable states in ecological systems at a local scale. Here, we explore whether particular geographic areas over the world display evidence for upcoming critical transitions in the temperature regime using five Early Warning Indicators (EWIs) commonly used in the literature. Although all EWIs revealed strong spatial variations regarding the likelihood of approaching transitions we found differences regarding the strength and the distribution of trends across the world, suggesting either that different mechanisms might be at play or that EWIs differ in their ability to detect approaching transitions. Nonetheless, a composite EWI, constructed from individual EWIs, showed congruent trends in several areas and highlighted variations across latitudes, between marine and terrestrial systems and among ecoregions within systems. Although the underlying mechanisms are unclear, our results suggest that some areas over the world might change toward an alternative temperature regime in the future with potential implications for the organisms inhabiting these areas.

Seasonal variations in diet composition, diet breadth and dietary overlap between three commercially important fish species within a flood-pulse system: The Tonle Sap Lake (Cambodia)

Tropical lakes and their associated floodplain habitats are dynamic habitat mosaics strongly influenced by seasonal variations in hydrologic conditions. In flood-pulse systems, water level oscillations directly influence the connectivity to floodplain habitats for fish. Here, we aimed to investigate whether seasonal changes in the water level of a flood-pulse system (the Tonle Sap Lake, Cambodia) differentially affect diet breadth and dietary overlap of three common and commercially important fish species (Anabas testudineus, Boesemania microplepis and Notopterus notopterus) presenting important differences in their life-cycle (e.g. seasonal migration). For this purpose, the three fish species were sampled at four locations spread over the lake and their stomach contents extracted for analyses. Dietary differences were investigated across seasons regarding the diet composition and diet breadth of each species as well as the amount of dietary overlap between species. We found that the proportion of empty stomachs changed similarly across seasons for the three species, thus suggesting that ecological differences between species are not sufficient to outweigh the effect of seasonal variations in resource abundance. In contrast, changes in diet composition were species-specific and can be explained by ecological and behavioral differences between species. Diet breadth differed between species in all seasons, except during the wet season, and tended to be higher during the dry season when dietary overlap was the lowest. These variations likely result from changes in the diversity and amount of resources and may lead to habitat use shifts with potential implications for competitive interactions. In particular, increasing connectivity to floodplain habitats may reduce the competitive pressure during the wet season, while resource scarcity during the dry season may constrain individuals to diversify their diet to avoid competition. Overall, our results suggest a considerable plasticity in the feeding behavior of the three species as demonstrated by seasonal variation in both diet breadth and dietary overlap. Such variations can be explained by a number of factors and processes, including changes in resource availability or competitive interactions between individuals for resources, whose relative influence might vary depending on the magnitude and the timing of the flood-pulse driving the connectivity to floodplain habitats. Gaining knowledge on the seasonal evolution of fish’s diet is relevant for fisheries management and conservation and our result could be used to guide aquaculture development in Cambodia.

Not every patient needs a triglyceride check, but all can get pancreatitis: a systematic review and clinical characterization of isotretinoin-associated pancreatitis

Monitoring of triglycerides for patients on isotretinoin is practised primarily to avoid hypertriglyceridaemia-associated pancreatitis. The aim of this study was to describe clinically the published cases of hypertriglyceride-associated pancreatitis. A comprehensive search strategy using MEDLINE, Embase and grey literature was conducted (1960 to January 2016) to identify all case reports of isotretinoin-associated pancreatitis and all relevant studies of isotretinoin and triglycerides for any indication (≥ 20 patients). Terms related to isotretinoin, triglycerides and pancreatitis were searched with all available synonyms. Any studies that used isotretinoin and mentioned triglycerides or pancreatitis were searched in full text, where available, for cases of pancreatitis. Studies from all countries and published in any language were included, but Korean and Turkish studies could not be analysed. Two authors independently reviewed the publications to determine eligibility, and for data extraction. In total, 125 papers fulfilled the inclusion criteria and were searched for cases of pancreatitis. Eleven papers with 25 cases of pancreatitis associated with isotretinoin were identified; four of these cases were likely due to hypertriglyceridaemia. Three patients had elevated baseline triglycerides, but no monitoring. Pancreatitis occurred 6 and 7 weeks, and 6 months after initiation of therapy. For the fourth patient who was treated for glioblastoma and died, no detailed clinical information was available. Idiosyncratic pancreatitis associated with isotretinoin is the most frequent pancreatitis on isotretinoin, and patients should be warned about it. Hypertriglyceride-associated pancreatitis is an exceedingly rare adverse event of isotretinoin therapy. Our data cannot give a frequency or risk for either adverse event. Based on the clinical information of the patients available, we conclude that for patients without elevated baseline triglycerides, or risk thereof, monitoring of triglycerides during therapy is of little value.