14 research outputs found
Learn-Morph-Infer: a new way of solving the inverse problem for brain tumor modeling
Current treatment planning of patients diagnosed with a brain tumor, such as glioma, could significantly benefit by accessing the spatial distribution of tumor cell concentration. Existing diagnostic modalities, e.g. magnetic resonance imaging (MRI), contrast sufficiently well areas of high cell density. In gliomas, however, they do not portray areas of low cell concentration, which can often serve as a source for the secondary appearance of the tumor after treatment. To estimate tumor cell densities beyond the visible boundaries of the lesion, numerical simulations of tumor growth could complement imaging information by providing estimates of full spatial distributions of tumor cells. Over recent years a corpus of literature on medical image-based tumor modeling was published. It includes different mathematical formalisms describing the forward tumor growth model. Alongside, various parametric inference schemes were developed to perform an efficient tumor model personalization, i.e. solving the inverse problem. However, the unifying drawback of all existing approaches is the time complexity of the model personalization which prohibits a potential integration of the modeling into clinical settings. In this work, we introduce a deep learning based methodology for inferring the patient-specific spatial distribution of brain tumors from T1Gd and FLAIR MRI medical scans. Coined as Learn-Morph-Infer the method achieves real-time performance in the order of minutes on widely available hardware and the compute time is stable across tumor models of different complexity, such as reaction-diffusion and reaction-advection-diffusion models. We believe the proposed inverse solution approach not only bridges the way for clinical translation of brain tumor personalization but can also be adopted to other scientific and engineering domains
Domestication of the green alga Chlorella sorokiniana: reduction of antenna size improves light-use efficiency in a photobioreactor
BACKGROUND: The utilization of biomass from microalgae for biofuel production is one of the key elements for the development of a sustainable and secure energy supply. Among the different microalgae, Chlorella species are of interest because of their high productivity, high lipid content, and resistance to the high light conditions typical of photobioreactors. However, the economic feasibility of growing algae at an industrial scale is yet to be realized, in part because of biological constraints that limit biomass yield. A key issue is the inefficient use of light due to uneven light distribution, and the dissipation of excess absorbed light as heat. The successful implementation of biofuel production facilities requires the development of algal strains with enhanced light use efficiency in photobioreactors. Such domestication strategies include decreasing the absorption cross section in order to enhance light penetration, increasing the size of metabolic sinks per chlorophyll and minimizing feedback energy dissipation.RESULTS:In this work we applied random mutagenesis and phenotypic selection to the thermotolerant, fast-growing Chlorella species, C. sorokiniana. Truncated antenna mutants (TAMs) were selected that exhibited a lower fluorescence yield than the wild-type (WT) strain. Six putatively interesting mutants were selected by high throughput fluorescence video imaging, two of which, TAM-2 and TAM-4, were found to have approximately half the chlorophyll content per cell and LHCII complement per PSII with respect to the WT. In batch culture, TAM-2 showed an increased photon use efficiency, yielding a higher Pmax at saturating irradiances with respect to the WT. Cultivation of TAM-2 in both laboratory-scale and outdoor photobioreactors showed higher productivity than WT, with a 30% higher biomass yield in dense cell suspensions typical of industrial photobioreactors.CONCLUSIONS:These results suggest that generation of mutants with low chlorophyll content can significantly improve the light-to-biomass conversion efficiency of C. sorokiniana under mass culture conditions. However, owing to the lack of sexual reproduction in this species, the presence of additional mutations might affect growth rate, suggesting that selection should include evaluation of multiple independent mutants for each desired phenotyp
Photosynthetic response to nitrogen starvation and high light in Haematococcus pluvialis
Astaxanthin is a carotenoid mainly produced by microalgae upon exposure to stress conditions: this pigment has
anti-oxidant, anti-inflammatory and anti-cancer capacity and it is widely used as pigmentation agent in different
industrial sectors. Abiotic stresses such as exposure to high irradiances and/or nitrogen starvation are commonly
used to induce astaxanthin biosynthesis in freshwater green alga Haematococcus pluvialis. In this work high light
and nitrogen deprivation were applied as single or combined stresses in order to investigate their influence on
the photosynthetic properties of H. pluvialis cultures. The results reported here demonstrate that nitrogen
starvation inhibits chlorophyll biosynthesis and favors chlorophyll b degradation, chlororespiration and cyclic
electron transport, while cells grown in high light are characterized by a higher destabilization of PSII. The
combination of high light and nitrogen deprivation induced the highest astaxanthin production and also the
fastest photoprotective response which cooperatively prevented Photosystem II from the damage observed in
high light stress and nitrogen supplemented medium. In these conditions inhibition of astaxanthin accumulation
leads to a reduced cell size but does not induce a higher photosensitivity of photosynthetic machinery
Domestication of the green alga Chlorella sorokiniana: reduction of antenna size improves light-use efficiency in a photobioreactor
BACKGROUND: The utilization of biomass from microalgae for biofuel production is one of the key elements for the development of a sustainable and secure energy supply. Among the different microalgae, Chlorella species are of interest because of their high productivity, high lipid content, and resistance to the high light conditions typical of photobioreactors. However, the economic feasibility of growing algae at an industrial scale is yet to be realized, in part because of biological constraints that limit biomass yield. A key issue is the inefficient use of light due to uneven light distribution, and the dissipation of excess absorbed light as heat. The successful implementation of biofuel production facilities requires the development of algal strains with enhanced light use efficiency in photobioreactors. Such domestication strategies include decreasing the absorption cross section in order to enhance light penetration, increasing the size of metabolic sinks per chlorophyll and minimizing feedback energy dissipation.RESULTS:In this work we applied random mutagenesis and phenotypic selection to the thermotolerant, fast-growing Chlorella species, C. sorokiniana. Truncated antenna mutants (TAMs) were selected that exhibited a lower fluorescence yield than the wild-type (WT) strain. Six putatively interesting mutants were selected by high throughput fluorescence video imaging, two of which, TAM-2 and TAM-4, were found to have approximately half the chlorophyll content per cell and LHCII complement per PSII with respect to the WT. In batch culture, TAM-2 showed an increased photon use efficiency, yielding a higher Pmax at saturating irradiances with respect to the WT. Cultivation of TAM-2 in both laboratory-scale and outdoor photobioreactors showed higher productivity than WT, with a 30% higher biomass yield in dense cell suspensions typical of industrial photobioreactors.CONCLUSIONS:These results suggest that generation of mutants with low chlorophyll content can significantly improve the light-to-biomass conversion efficiency of C. sorokiniana under mass culture conditions. However, owing to the lack of sexual reproduction in this species, the presence of additional mutations might affect growth rate, suggesting that selection should include evaluation of multiple independent mutants for each desired phenotyp
Isolation and characterization of a Scenedesmus acutus strainto be used for bioremediation of urban wastewater
Green microalgae, due to their short growth
cycle and to their ability to photosynthetically fix carbon
dioxide producing an oil-rich biomass, have been proposed
as an attractive alternative feedstock for the production of
âsecond generationâ biofuels. However, it has been anticipated
that owing to their ability to colonize very different
environments characterized by high levels of nitrogen, they
can also be good candidates for bioremediation, thus
integrating environmental protection with sustainable biomass
production. We have isolated a strain belonging to
Scenedesmus genus from urban wastewater. This isolate,
Scenedesmus acutus PVUW12, was tested for its ability to
grow and actively deplete eutrophicating inorganic molecules
present in wastewater. In order to test its biomass
productivity, the PVUW12 strain was grown in a verticalcolumn
photobioreactor using standard growth medium
obtaining a maximal productivity of 0.3 g dry weight Lâ1 d.
When the same strain was grown in the photobioreactor
filled with wastewater collected from the final step of the
local urban purifier plant containing 18.8 mg Lâ1
nitrate, we observed complete nitrogen removal coupled
with a biomass production of about 0.74 g dry weight Lâ1
within 3 days. After 10 days, the recovered biomass was
analyzed for triglyceride content which was found to be
9.3% of the dry biomass. However, when algal cells were
left for additional 10 days in static conditions the
triglyceride content increased to 28.8%. These data show
that this Scenedesmus strain can be used for wastewater
bioremediation producing a biomass suitable for energy
production
Cyclic fatigue comparison among endodontic instruments with similar cross section and different surface coating
The aim of this study was to analyze the influence of rotary instruments' geometry and surface titanium-nitride (TiN) treatment on the fatigue fracture, through the comparison of cyclic fatigue resistance of two endodontic systems that have similar cross-sectional design and different surface coating
Tolerated drugs in subjects with severe cutaneous adverse reactions (SCARs) induced by anticonvulsants and review of the literature
Abstract Background Anticonvulsant hypersensitivity syndrome represents a rare but potentially fatal kind of adverse drug reaction. This clinical picture often hampers the flexibility with which alternative anticonvulsants or even other classes of drugs are prescribed in these patients, negatively affecting the efficacy of treatment and the course of the disease. The aim of this study was to analyse a group of six patients with severe cutaneous drug reactions induced by anticonvulsants and to report which alternative antiepileptic drugs and which drugs of other classes were tolerated. Case presentation A total of six patients (2 males and 4 females, age 11â73Â years) are described in this study. In all the patients the onset of the severe cutaneous drug reactions was 2â4Â weeks after initiating the anticonvulsant therapy: 2 out of 6 patients presented with a drug reaction with eosinophilia and systemic symptoms under therapy with phenytoin; 2 out of 6 presented with StevensâJohnson syndrome under therapy with lamotrigine; and 2 out of 6 presented with a toxic epidermal necrolysis, one of them under therapy with valproic acid, and the other one under therapy with lamotrigine. Alternative anticonvulsants tolerated after the reaction were: clonazepam, levetiracetam, diazepam, delorazepam and lormetazepam. Conclusions In our cases we observed that non aromatic anticonvulsants and benzodiazepines were well tolerated as alternative treatments in six patients with reactions to aromatic anticonvulsivants and that the risk of hypersensitivity reactions to other drug classes was not increased as compared to general population
Scomparsa del ritmo circadiano della frequenza cardiaca nel trapianto di cuore in fase di rigetto acuto.
The present study is aimed to investigate the circadian rhythm (CR) of heart rate (HR) in acute rejecting and non-rejecting heart transplanted patients (HTP). The purpose is to provide evidence that an impairment in the HR CR may have a role in predicting episodes of acute rejection in HTP. The study was carried out on 32 Holter monitorings of 13 patients: 9 Holter monitorings were carried out during an episode of acute rejection documented by endomyocardial biopsy. Time data series were analyzed by Cosinor method in order to validate the occurrence of HR CR. The Cosinor analysis found a highly statistically significant HR CR in non-rejecting HTP. The occurrence of the HR CR was not statistically validated in acute rejecting HTP. These findings suggest that the lack of a periodic variability in the 24-hour HR pattern may be useful to diagnose acute heart rejection
Role of Multiple Comorbidities and Therapies in Conditioning the Clinical Severity of DRESS: A Mono-Center Retrospective Study of 25 Cases
DRESS/DiHS is a complex and potentially fatal drug reaction. Little is known about risk factors and elements that can help to identify patients with a severe reaction early. The aim of the study was to investigate those factors favoring the disease and its severity by analyzing the clinical conditions and therapies preceding the reaction. We conducted a retrospective analysis on patients admitted to our center between 2010 and 2020 who were discharged with a diagnosis of DRESS. We used the RegiSCAR diagnostic criteria. We defined the severity of DRESS using the criteria of Mizukawa et al. We included 25 patients (15 females) with a median age of 66 years. Skin involvement, eosinophilia, and liver injury were the most important aspects. Allopurinol was found to be the most involved drug. Reaction severity was significantly associated with the number of daily medications (p = 0.0067) and an age of at least 68 years (p = 0.013). In addition, 75% of severe cases had at least three comorbidities in history, and most of the severe cases were female. In our study the advanced age, the high number of comorbidities and home therapies, and the inflammatory state were found to be predisposing elements to the development of the disease and its severity
Primary Endoscopic Endonasal Management of Giant Pituitary Adenomas: Outcome and Pitfalls from a Large Prospective Multicenter Experience
Purpose: To evaluate factors influencing clinical and radiological outcome of extended endoscopic endonasal transtuberculum/transplanum approach (EEA-TTP) for giant pituitary adenomas (GPAs). Methods: We recruited prospectively all consecutive GPAs patients undergoing EEA-TTP between 2015 and 2019 in 5 neurosurgical centers. Preoperative clinical and radiologic features, visual and hormonal outcomes, extent of resection (EoR), complications and recurrence rates were recorded and analyzed. Results: Of 1169 patients treated for pituitary adenoma, 96 (8.2%) had GPAs. Seventy-eight (81.2%) patients had visual impairment, 12 (12.5%) had headaches, 3 (3.1%) had drowsiness due to hydrocephalus, and 53 (55.2%) had anterior pituitary insufficiency. EoR was gross or near-total in 46 (47.9%) and subtotal in 50 (52.1%) patients. Incomplete resection was associated with lateral suprasellar, intraventricular and/or cavernous sinus extension and with firm/fibrous consistence. At the last follow-up, all but one patient (77, 98.7%) with visual deficits improved. Headache improved in 8 (88.9%) and anterior pituitary function recovered in 27 (50.9%) patients. Recurrence rate was 16.7%, with 32 months mean recurrence-free survival. Conclusions: EEA-TTP is a valid option for GPAs and seems to provide better outcomes, lower rate of complications and higher EoR compared to one- or multi-stage microscopic, non-extended endoscopic transsphenoidal, and transcranial resections