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1.
J Health Organ Manag ; 38(9): 45-71, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38448230

RESUMO

PURPOSE: Society is critically dependent on an adequate supply of hospital doctors to ensure optimal health care. Voluntary turnover amongst hospital doctors is, however, an increasing problem for hospitals. The aim of this study was to systematically review the extant academic literature to obtain a comprehensive understanding of the current knowledge base on hospital doctor turnover and retention. In addition to this, we synthesise the most common methodological approaches used before then offering an agenda to guide future research. DESIGN/METHODOLOGY/APPROACH: Adopting the PRISMA methodology, we conducted a systematic literature search of four databases, namely CINAHL, MEDLINE, PsycINFO and Web of Science. FINDINGS: We identified 51 papers that empirically examined hospital doctor turnover and retention. Most of these papers were quantitative, cross-sectional studies focussed on meso-level predictors of doctor turnover. RESEARCH LIMITATIONS/IMPLICATIONS: Selection criteria concentrated on doctors who worked in hospitals, which limited knowledge of one area of the healthcare environment. The review could disregard relevant articles, such as those that discuss the turnover and retention of doctors in other specialities, including general practitioners. Additionally, being limited to peer-reviewed published journals eliminates grey literature such as dissertations, reports and case studies, which may bring impactful results. PRACTICAL IMPLICATIONS: Globally, hospital doctor turnover is a prevalent issue that is influenced by a variety of factors. However, a lack of focus on doctors who remain in their job hinders a comprehensive understanding of the issue. Conducting "stay interviews" with doctors could provide valuable insight into what motivates them to remain and what could be done to enhance their work conditions. In addition, hospital management and recruiters should consider aspects of job embeddedness that occur outside of the workplace, such as facilitating connections outside of work. By resolving these concerns, hospitals can retain physicians more effectively and enhance their overall retention efforts. SOCIAL IMPLICATIONS: Focussing on the reasons why employees remain with an organisation can have significant social repercussions. When organisations invest in gaining an understanding of what motivates their employees to stay in the job, they are better able to establish a positive work environment that likely to promote employee well-being and job satisfaction. This can result in enhanced job performance, increased productivity and higher employee retention rates, all of which are advantageous to the organisation and its employees. ORIGINALITY/VALUE: The review concludes that there has been little consideration of the retention, as opposed to the turnover, of hospital doctors. We argue that more expansive methodological approaches would be useful, with more qualitative approaches likely to be particularly useful. We also call on future researchers to consider focussing further on why doctors remain in posts when so many are leaving.


Assuntos
Hospitais , Reorganização de Recursos Humanos , Médicos , Humanos , Instalações de Saúde
2.
Eur J Radiol ; 166: 110983, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37480648

RESUMO

PURPOSE: Imaging stents and in-stent stenosis remains a challenge in coronary computed tomography angiography (CCTA). In comparison to conventional Computed Tomography, Photon Counting CT (PCCT) provides decisive clinical advantages, among other things by providing low dose ultra-high resolution imaging of coronary arteries. This work investigates the image quality in CCTA using clinically established kernels and those optimized for the imaging of cardiac stents in PCCT, both for in-vitro stent imaging in 400 µm standard resolution mode (SRM) and 200 µm Ultra High Resolution Mode (UHR). METHODS: Based on experimental scans, vascular reconstruction kernels (Bv56, Bv64, Bv72) were optimized. In an established phantom, 10 different coronary stents with 3 mm diameter were scanned in the first clinically available PCCT. Scans were reconstructed with clinically established and optimized kernels. Four readers measured visible stent lumen, performed ROI-based density measurements and rated image quality. RESULTS: Regarding the visible stent lumen, UHR is significantly superior to SRM (p < 0.001). In all levels, the optimized kernels are superior to the clinically established kernels (p < 0.001). One optimized kernel showed a significant reduction of noise compared to the clinically established kernels. Overall image quality is improved with optimized kernels. CONCLUSIONS: In a phantom study PCCT UHR with optimized kernels for stent imaging significantly improves the ability to assess the in-stent lumen of small cardiac stents. We recommend using UHR with an optimized sharp vascular reconstruction kernel (Bv72uo) for imaging of cardiac stent.


Assuntos
Angiografia , Tomografia Computadorizada por Raios X , Humanos , Imagens de Fantasmas , Angiografia por Tomografia Computadorizada , Stents
3.
Eng Life Sci ; 23(1): e2100169, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36619880

RESUMO

Acetobacterium woodii is known to produce mainly acetate from CO2 and H2, but the production of higher value chemicals is desired for the bioeconomy. Using chain-elongating bacteria, synthetic co-cultures have the potential to produce longer-chained products such as caproic acid. In this study, we present first results for a successful autotrophic co-cultivation of A. woodii mutants and a Clostridium drakei wild-type strain in a stirred-tank bioreactor for the production of caproic acid from CO2 and H2 via the intermediate lactic acid. For autotrophic lactate production, a recombinant A. woodii strain with a deleted Lct-dehydrogenase complex, which is encoded by the lctBCD genes, and an inserted D-lactate dehydrogenase (LdhD) originating from Leuconostoc mesenteroides, was used. Hydrogen for the process was supplied using an All-in-One electrode for in situ water electrolysis. Lactate concentrations as high as 0.5 g L-1 were achieved with the AiO-electrode, whereas 8.1 g L-1 lactate were produced with direct H2 sparging in a stirred-tank bioreactor. Hydrogen limitation was identified in the AiO process. However, with cathode surface area enlargement or numbering-up of the electrode and on-demand hydrogen generation, this process has great potential for a true carbon-negative production of value chemicals from CO2.

4.
Diagnostics (Basel) ; 13(2)2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36673092

RESUMO

The purpose of this phantom study was to compare the accuracy, speed and technical performance of CT guided needle placement using a conventional technique versus a novel, gantry integrated laser guidance system for both an expert and a novice. A total of 80 needle placements were performed in an abdominal phantom using conventional CT guidance and a laser guidance system. Analysis of pooled results of expert and novice showed a significant reduction of time (277 vs. 204 s, p = 0.001) and of the number of needle corrections (3.28 vs. 1.58, p < 0.001) required when using laser guidance versus conventional technique. No significant improvement in absolute (3.81 vs. 3.41 mm, p = 0.213) or angular deviation (2.85 vs. 2.18°, p = 0.079) was found. With either approach, the expert was significantly faster (conventional guidance: 207 s vs. 346 s, p < 0.001; laser guidance: 144 s vs. 264 s, p < 0.001) and required fewer needle corrections (conventional guidance: 4 vs. 3, p = 0.027; laser guidance: 2 vs. 1, p = 0.001) than the novice. The laser guidance system helped both the expert and the novice to perform CT guided interventions in a phantom faster and with fewer needle corrections compared to the conventional technique, while achieving similar accuracy.

5.
Risk Anal ; 43(11): 2151-2157, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-36717212

RESUMO

The discrepancy between formal arrangements to ensure health security, as assessed in the Global Health Security Index, and COVID-19 outcomes points to a broader problem where formal risk recognition is de-coupled from potentially resource-intensive follow-up policy implementation. Germany is an extreme example of this. Pre-COVID-19, Germany's Federal Office of Civilian Protection conducted two pandemic preparation exercises based on scenarios which closely mirrored the current COVID-19 pandemic: (a) a multi-jurisdictional, multi-agency crisis management exercise assuming a global influenza pandemic and (b) a joint federal and expert-agency based risk-analysis assuming the outbreak of a modified severe acute respiratory symptom virus. While informing legal and institutional reforms, key recommendations on storing personal protective equipment (PPE) and disinfectants for front-line staff were subsequently ignored. PPE shortages initially put staff at risk, led to export restrictions on PPE, and later on hampered the country's ability to address a second wave of the pandemic. This short paper calls for a fuller exploration of factors which hinder ''implementation post-cognition.''.


Assuntos
COVID-19 , Corrida , Humanos , Pandemias/prevenção & controle , Seguimentos , Equipamento de Proteção Individual
6.
AJR Am J Roentgenol ; 220(1): 73-85, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-35731096

RESUMO

BACKGROUND. Anatomic redundancy between phases can be used to achieve denoising of multiphase CT examinations. A limitation of iterative reconstruction (IR) techniques is that they generally require use of CT projection data. A frequency-split multi-band-filtration algorithm applies denoising to the multiphase CT images themselves. This method does not require knowledge of the acquisition process or integration into the reconstruction system of the scanner, and it can be implemented as a supplement to commercially available IR algorithms. OBJECTIVE. The purpose of the present study is to compare radiologists' performance for low-contrast and high-contrast diagnostic tasks (i.e., tasks for which differences in CT attenuation between the imaging target and its anatomic background are subtle or large, respectively) evaluated on multiphase abdominal CT between routine-dose images and radiation dose-reduced images processed by a frequency-split multiband-filtration denoising algorithm. METHODS. This retrospective single-center study included 47 patients who underwent multiphase contrast-enhanced CT for known or suspected liver metastases (a low-contrast task) and 45 patients who underwent multiphase contrast-enhanced CT for pancreatic cancer staging (a high-contrast task). Radiation dose-reduced images corresponding to dose reduction of 50% or more were created using a validated noise insertion technique and then underwent denoising using the frequency-split multi-band-filtration algorithm. Images were independently evaluated in multiple sessions by different groups of abdominal radiologists for each task (three readers in the low-contrast arm and four readers in the high-contrast arm). The noninferiority of denoised radiation dose-reduced images to routine-dose images was assessed using the jackknife alternative free-response ROC (JAFROC) figure-of-merit (FOM; limit of noninferiority, -0.10) for liver metastases detection and using the Cohen kappa statistic and reader confidence scores (100-point scale) for pancreatic cancer vascular invasion. RESULTS. For liver metastases detection, the JAFROC FOM for denoised radiation dose-reduced images was 0.644 (95% CI, 0.510-0.778), and that for routine-dose images was 0.668 (95% CI, 0.543-0.792; estimated difference, -0.024 [95% CI, -0.084 to 0.037]). Intraobserver agreement for pancreatic cancer vascular invasion was substantial to near perfect when the two image sets were compared (κ = 0.53-1.00); the 95% CIs of all differences in confidence scores between image sets contained zero. CONCLUSION. Multiphase contrast-enhanced abdominal CT images with a radiation dose reduction of 50% or greater that undergo denoising by a frequency-split multiband-filtration algorithm yield performance similar to that of routine-dose images for detection of liver metastases and vascular staging of pancreatic cancer. CLINICAL IMPACT. The image-based denoising algorithm facilitates radiation dose reduction of multiphase examinations for both low- and high-contrast diagnostic tasks without requiring manufacturer-specific hardware or software.


Assuntos
Neoplasias Hepáticas , Tomografia Computadorizada por Raios X , Humanos , Estudos Retrospectivos , Doses de Radiação , Tomografia Computadorizada por Raios X/métodos , Neoplasias Hepáticas/diagnóstico por imagem , Algoritmos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos
7.
J Med Access ; 6: 27550834221123425, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36204525

RESUMO

Prior to the outbreak of the COVID pandemic, pharmaceutical shortages were already recognised as a major policy problem by most, if not all, European governments; and virtually all European national governments today publicise official shortage lists. Policy making in the area has been centred on the national government level, which meant that the understanding, definition, and response to shortages has remained highly heterogeneous. When the advent of the COVID pandemic exacerbated shortages, this situation continued against a background of a weak collective European response. As part of their responses to COVID-shortages, the medicines regulators of European countries expanded the range of products pharmacies could manufacture, process and distribute as well as their procedural authority in issuing, handling and processing prescriptions. While these measures were fairly common across Europe and alleviated some bottlenecks or improved medicine access for some patient groups, other responses were highly individualistic and included export bans of certain medications as well as efforts to draw on veterinary supplies. Our own data analysis of officially recorded shortage data during the first COVID wave (to October 2020) indicates that countries that had prepared for these types of crisis and maintained an active policy stance (e.g. Germany and Norway) were more likely to encounter fewer shortages than others. We also note that there is no direct correlation between officially recorded numbers of shortages and the ways in which national governments responded to these - which indicates that cultural expectations also might have been a significant policy driver.

8.
Artigo em Inglês | MEDLINE | ID: mdl-36232071

RESUMO

Smart regulation, better regulation, responsive regulation, business-friendly regulation and voluntary 'self-regulation' have their origins deeply embedded in UK policies in the 20th century. Their aim generally is to reduce workplace regulatory obligations on employers. This can overtly or covertly undermine efforts to improve working conditions. In the UK, the historical control and regulation of beryllium (a toxic metal used in industry) illustrates this problem, and as we illustrate through an exploratory analysis of original archival material and official publications. Soft touch regulation of the metal beryllium was developed within the UK semiconductor industry when tighter controls were proposed in the 1960s and 1970s. Historical industry, government and science responses to health and safety information about beryllium provide important lessons for current debates on occupational health and safety.


Assuntos
Exposição Ocupacional , Saúde Ocupacional , Berílio/análise , Indústrias , Exposição Ocupacional/análise , Exposição Ocupacional/prevenção & controle , Tato , Reino Unido
9.
Artigo em Inglês | MEDLINE | ID: mdl-36293717

RESUMO

Although several countries have experienced large-scale privatization initiatives, relatively little is known about the impact of these initiatives on the health and safety of workers and resident populations. Examining data on technical (as compared to natural) multi-fatality disasters collected in the WHO's Emergency Events Database (EM-DAT) for the UK and a number of European comparator countries for recent decades, this paper shows that the incidence of these disasters and the number of deaths resulting from them rose significantly in the UK during the period from 1979 to 1991 when the country engaged in extensive and aggressive privatization campaigns which were supported by several consecutive Conservative governments. This observed UK blip or abnormal increase in multi-fatality disasters is apparent for the UK both in terms of a "within-country" comparison (i.e., when we compare the privatization period of 1979 to 1997 with other periods), as well as when viewed in terms of comparisons with the comparable European countries of Germany, France, and Italy for the same period (1979 to 1997). Contrary to previous analyses which suggested that there is no clear link between privatization and deterioration of health and safety, this paper concludes that the UK privatization experience (1979-1997) provides robust country-specific evidence of privatization initiatives leading to increases in the number of multi-fatality technological disasters as well as related fatalities. This evidence should be seen as a deterrent to similarly extensive and aggressive initiatives which, particularly in less developed countries, could result in similarly disastrous outcomes.


Assuntos
Desastres , Privatização , Humanos , Europa (Continente) , Causalidade , Reino Unido/epidemiologia
10.
Invest Radiol ; 57(12): 780-788, 2022 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-35640019

RESUMO

OBJECTIVES: The aim of this study was to evaluate the feasibility and quality of ultra-high-resolution coronary computed tomography angiography (CCTA) with dual-source photon-counting detector CT (PCD-CT) in patients with a high coronary calcium load, including an analysis of the optimal reconstruction kernel and matrix size. MATERIALS AND METHODS: In this institutional review board-approved study, 20 patients (6 women; mean age, 79 ± 10 years; mean body mass index, 25.6 ± 4.3 kg/m 2 ) undergoing PCD-CCTA in the ultra-high-resolution mode were included. Ultra-high-resolution CCTA was acquired in an electrocardiography-gated dual-source spiral mode at a tube voltage of 120 kV and collimation of 120 × 0.2 mm. The field of view (FOV) and matrix sizes were adjusted to the resolution properties of the individual reconstruction kernels using a FOV of 200 × 200 mm 2 or 150 × 150 mm 2 and a matrix size of 512 × 512 pixels or 1024 × 1024 pixels, respectively. Images were reconstructed using vascular kernels of 8 sharpness levels (Bv40, Bv44, Bv56, Bv60, Bv64, Bv72, Bv80, and Bv89), using quantum iterative reconstruction (QIR) at a strength level of 4, and a slice thickness of 0.2 mm. Images with the Bv40 kernel, QIR at a strength level of 4, and a slice thickness of 0.6 mm served as the reference. Image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), vessel sharpness, and blooming artifacts were quantified. For subjective image quality, 2 blinded readers evaluated image noise and delineation of coronary artery plaques and the adjacent vessel lumen using a 5-point discrete visual scale. A phantom scan served to characterize image noise texture by calculating the noise power spectrum for every reconstruction kernel. RESULTS: Maximum spatial frequency (f peak ) gradually shifted to higher values for reconstructions with the Bv40 to Bv64 kernel (0.15 to 0.56 mm -1 ), but not for reconstructions with the Bv72 to Bv89 kernel. Ultra-high-resolution CCTA was feasible in all patients (median calcium score, 479). In patients, reconstructions with the Bv40 kernel and a slice thickness of 0.6 mm showed largest blooming artifacts (55.2% ± 9.8%) and lowest vessel sharpness (477.1 ± 73.6 ΔHU/mm) while achieving highest SNR (27.4 ± 5.6) and CNR (32.9 ± 6.6) and lowest noise (17.1 ± 2.2 HU). Considering reconstructions with a slice thickness of 0.2 mm, image noise, SNR, CNR, vessel sharpness, and blooming artifacts significantly differed across kernels (all P 's < 0.001). With higher kernel sharpness, SNR and CNR continuously decreased, whereas image noise and vessel sharpness increased, with highest sharpness for the Bv89 kernel (2383.4 ± 787.1 ΔHU/mm). Blooming artifacts continuously decreased for reconstructions with the Bv40 (slice thickness, 0.2 mm; 52.8% ± 9.2%) to the Bv72 kernel (39.7% ± 9.1%). Subjective noise was perceived by both readers in agreement with the objective measurements. Considering delineation of coronary artery plaques and the adjacent vessel lumen, reconstructions with the Bv64 and Bv72 kernel (for both, median score of 5) were favored by the readers providing an excellent anatomic delineation of plaque characteristics and vessel lumen. CONCLUSIONS: Ultra-high-resolution CCTA with PCD-CT is feasible and enables the visualization of calcified coronaries with an excellent image quality, high sharpness, and reduced blooming. Coronary plaque characterization and delineation of the adjacent vessel lumen are possible with an optimal quality using Bv64 kernel, a FOV of 200 × 200 mm 2 , and a matrix size of 512 × 512 pixels.


Assuntos
Cálcio , Angiografia por Tomografia Computadorizada , Humanos , Feminino , Idoso , Idoso de 80 Anos ou mais , Estudos de Viabilidade , Tomografia Computadorizada por Raios X/métodos , Imagens de Fantasmas , Angiografia Coronária/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos
11.
Appl Microbiol Biotechnol ; 106(4): 1447-1458, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35092454

RESUMO

Lactate has various uses as industrial platform chemical, poly-lactic acid precursor or feedstock for anaerobic co-cultivations. The aim of this study was to construct and characterise Acetobacterium woodii strains capable of autotrophic lactate production. Therefore, the lctBCD genes, encoding the native Lct dehydrogenase complex, responsible for lactate consumption, were knocked out. Subsequently, a gene encoding a D-lactate dehydrogenase (LDHD) originating from Leuconostoc mesenteroides was expressed in A. woodii, either under the control of the anhydrotetracycline-inducible promoter Ptet or under the lactose-inducible promoter PbgaL. Moreover, LDHD was N-terminally fused to the oxygen-independent fluorescence-activating and absorption-shifting tag (FAST) and expressed in respective A. woodii strains. Cells that produced the LDHD fusion protein were capable of lactate production of up to 18.8 mM in autotrophic batch experiments using H2 + CO2 as energy and carbon source. Furthermore, cells showed a clear and bright fluorescence during exponential growth, as well as in the stationary phase after induction, mediated by the N-terminal FAST. Flow cytometry at the single-cell level revealed phenotypic heterogeneities for cells expressing the FAST-tagged LDHD fusion protein. This study shows that FAST provides a new reporter tool to quickly analyze gene expression over the course of growth experiments of A. woodii. Consequently, fluorescence-based reporters allow for faster and more targeted optimization of production strains.Key points •Autotrophic lactate production was achieved with A. woodii. •FAST functions as fluorescent marker protein in A. woodii. •Fluorescence measurements on single-cell level revealed population heterogeneity.


Assuntos
Dióxido de Carbono , Ácido Láctico , Acetatos/metabolismo , Acetobacterium , Dióxido de Carbono/metabolismo , Fluorescência
12.
Biomed Phys Eng Express ; 8(2)2022 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-34983885

RESUMO

The problem of data truncation in Computed Tomography (CT) is caused by the missing data when the patient exceeds the Scan Field of View (SFOV) of a CT scanner. The reconstruction of a truncated scan produces severe truncation artifacts both inside and outside the SFOV. We have employed a deep learning-based approach to extend the field of view and suppress truncation artifacts. Thereby, our aim is to generate a good estimate of the real patient data and not to provide a perfect and diagnostic image even in regions beyond the SFOV of the CT scanner. This estimate could then be used as an input to higher order reconstruction algorithms [1]. To evaluate the influence of the network structure and layout on the results, three convolutional neural networks (CNNs), in particular a general CNN called ConvNet, an autoencoder, and the U-Net architecture have been investigated in this paper. Additionally, the impact of L1, L2, structural dissimilarity and perceptual loss functions on the neural network's learning have been assessed and evaluated. The evaluation of data set comprising 12 truncated test patients demonstrated that the U-Net in combination with the structural dissimilarity loss showed the best performance in terms of image restoration in regions beyond the SFOV of the CT scanner. Moreover, this network produced the best mean absolute error, L1, L2, and structural dissimilarity evaluation measures on the test set compared to other applied networks. Therefore, it is possible to achieve truncation artifact removal using deep learning techniques.


Assuntos
Aprendizado Profundo , Artefatos , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imagens de Fantasmas , Tomografia Computadorizada por Raios X/métodos
13.
Med Phys ; 48(7): 3583-3594, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33978240

RESUMO

PURPOSE: Modern computed tomography (CT) scanners have an extended field-of-view (eFoV) for reconstructing images up to the bore size, which is relevant for patients with higher BMI or non-isocentric positioning due to fixation devices. However, the accuracy of the image reconstruction in eFoV is not well known since truncated data are used. This study introduces a new deep learning-based algorithm for extended field-of-view reconstruction and evaluates the accuracy of the eFoV reconstruction focusing on aspects relevant for radiotherapy. METHODS: A life-size three-dimensional (3D) printed thorax phantom, based on a patient CT for which eFoV was necessary, was manufactured and used as reference. The phantom has holes allowing the placement of tissue mimicking inserts used to evaluate the Hounsfield unit (HU) accuracy. CT images of the phantom were acquired using different configurations aiming to evaluate geometric and HU accuracy in the eFoV. Image reconstruction was performed using a state-of-the-art reconstruction algorithm (HDFoV), commercially available, and the novel deep learning-based approach (HDeepFoV). Five patient cases were selected to evaluate the performance of both algorithms on patient data. There is no ground truth for patients so the reconstructions were qualitatively evaluated by five physicians and five medical physicists. RESULTS: The phantom geometry reconstructed with HDFoV showed boundary deviations from 1.0 to 2.5 cm depending on the volume of the phantom outside the regular scan field of view. HDeepFoV showed a superior performance regardless of the volume of the phantom within eFOV with a maximum boundary deviation below 1.0 cm. The maximum HU (absolute) difference for soft issue inserts is below 79 and 41 HU for HDFoV and HDeepFoV, respectively. HDeepFoV has a maximum deviation of -18 HU for an inhaled lung insert while HDFoV reached a 229 HU difference. The qualitative evaluation of patient cases shows that the novel deep learning approach produces images that look more realistic and have fewer artifacts. CONCLUSION: To be able to reconstruct images outside the sFoV of the CT scanner there is no alternative than to use some kind of extrapolated data. In our study, we proposed and investigated a new deep learning-based algorithm and compared it to a commercial solution for eFoV reconstruction. The deep learning-based algorithm showed superior performance in quantitative evaluations based on phantom data and in qualitative assessments of patient data.


Assuntos
Algoritmos , Tomografia Computadorizada por Raios X , Artefatos , Humanos , Processamento de Imagem Assistida por Computador , Imagens de Fantasmas , Tomógrafos Computadorizados
14.
Appl Microbiol Biotechnol ; 104(2): 687-699, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31807888

RESUMO

The advantage of using acetogens such as Acetobacterium woodii as biocatalysts converting the cheap substrate and greenhouse gas carbon dioxide (CO2) into value-added chemicals comes together with the disadvantage of a low overall ATP gain due to the bioenergetics associated with the Wood-Ljungdahl pathway. Expanding the product spectrum of recombinant A. woodii strains to compounds with high ATP-demanding biosynthesis is therefore challenging. As a least invasive strategy for improved ATP generation, the exploitation of the arginine deiminase pathway (ADI) was examined under native conditions and via using heterologously expressed genes in A. woodii. Several promoters were analyzed for application of different gene expression levels in A. woodii using ß-glucuronidase assays. Heterologous expression of the ADI pathway genes from Clostridium autoethanogenum was controlled using either the constitutive pta-ack promoter from Clostridium ljungdahlii or a tightly regulated tetracycline-inducible promoter Ptet. Unlike constitutive expression, only induced expression of the ADI pathway genes led to a 36% higher maximal OD600 when using arginine (OD600 3.4) as nitrogen source and a 52% lower acetate yield per biomass compared to cells growing with yeast extract as nitrogen source (OD600 2.5). In direct comparison, a 69% higher maximal OD600 and about 60% lower acetate yield per biomass in induced to non-induced recombinant A. woodii cells was noticed when using arginine. Our data suggests the application of the ADI pathway in A. woodii for expanding the product spectrum to compounds with high ATP-demanding biosynthesis.


Assuntos
Acetobacterium/enzimologia , Acetobacterium/crescimento & desenvolvimento , Expressão Gênica , Hidrolases/metabolismo , Engenharia Metabólica , Redes e Vias Metabólicas/genética , Proteínas Recombinantes/metabolismo , Acetatos/metabolismo , Acetobacterium/genética , Arginina/metabolismo , Clostridium/enzimologia , Clostridium/genética , Hidrolases/genética , Nitrogênio/metabolismo , Regiões Promotoras Genéticas , Proteínas Recombinantes/genética , Ativação Transcricional
15.
Parasit Vectors ; 12(1): 354, 2019 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-31311590

RESUMO

BACKGROUND: The analysis of large mosquito samples is expensive and time-consuming, delaying the efficient timing of vector control measurements. Processing a fraction of a sample using a subsampling method can significantly reduce the processing effort. However, a comprehensive evaluation of the reliability of different subsampling methods is missing. METHODS: A total of 23 large mosquito samples (397-4713 specimens per sample) were compared in order to evaluate five subsampling methods for the estimation of the number of specimens and species: area, volume, weight, selection of 200 random specimens and analyses with an image processing software. Each sample was distributed over a grid paper (21.0 × 29.7 cm; 25 grid cells of 4.2 × 5.9 cm) with 200 randomly distributed points. After taking pictures, mosquito specimens closest to each of the 200 points on the paper were selected. All mosquitoes per grid cell were identified by morphology and transferred to scaled tubes to estimate the volume. Finally, the fresh and dry weights were determined. RESULTS: The estimated number of specimens and species did not differ between the area-, volume- and weight-based method. Subsampling 20% of the sample gave an error rate of approximately 12% for the number of specimens, 6% for the proportion of the most abundant species and between 6-40% for the number of species per sample. The error for the estimated number of specimens using the picture processing software ImageJ gave a similar error rate when analyzing 15-20% of the total sample. By using 200 randomly selected specimens it was possible to give a precise estimation of the proportion of the most abundant species (r = 0.97, P < 0.001), but the number of species per sample was underestimated by 28% on average. Selecting adjacent grid cells instead of sampling randomly chosen grid cells and using dry weight instead of wet weight did not increase the accuracy of estimates. CONCLUSIONS: Different subsampling methods have various advantages and disadvantages. However, the area-based analysis of 20% of the sample is probably the most suitable approach for most kinds of mosquito studies, giving sufficiently precise estimations of the number of specimens and species, which is slightly less laborious compared to the other methods tested.


Assuntos
Culicidae , Estudos de Amostragem , Animais , Mosquitos Vetores , Reprodutibilidade dos Testes , Estatística como Assunto
16.
Adv Appl Microbiol ; 103: 143-221, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29914657

RESUMO

Anaerobic bacterial gas fermentation gains broad interest in various scientific, social, and industrial fields. This microbial process is carried out by a specific group of bacterial strains called acetogens. All these strains employ the Wood-Ljungdahl pathway but they belong to different taxonomic groups. Here we provide an overview of the metabolism of acetogens and naturally occurring products. Characteristics of 61 strains were summarized and selected acetogens described in detail. Acetobacterium woodii, Clostridium ljungdahlii, and Moorella thermoacetica serve as model organisms. Results of approaches such as genome-scale modeling, proteomics, and transcriptomics are discussed. Metabolic engineering of acetogens can be used to expand the product portfolio to platform chemicals and to study different aspects of cell physiology. Moreover, the fermentation of gases requires specific reactor configurations and the development of the respective technology, which can be used for an industrial application. Even though the overall process will have a positive effect on climate, since waste and greenhouse gases could be converted into commodity chemicals, some legislative barriers exist, which hamper successful exploitation of this technology.


Assuntos
Bactérias Anaeróbias/metabolismo , Produtos Biológicos/metabolismo , Dióxido de Carbono/metabolismo , Gases/metabolismo , Hidrogênio/metabolismo , Anaerobiose , Fermentação , Perfilação da Expressão Gênica , Redes e Vias Metabólicas , Metaboloma , Proteoma/análise
17.
Neuroimage Clin ; 18: 1-8, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29321971

RESUMO

Theoretical models and recent advances in the treatment of anorexia nervosa (AN) have increasingly focused on the role of alterations in the processing and regulation of emotions. To date, however, our understanding of these changes is still limited and reports of emotional dysregulation in AN have been based largely on self-report data, and there is a relative lack of objective experimental evidence or neurobiological data. The current functional magnetic resonance imaging (fMRI) study investigated the hemodynamic correlates of passive viewing and voluntary downregulation of negative emotions by means of the reappraisal strategy detachment in AN patients. Detachment is regarded as adaptive regulation strategy associated with a reduction in emotion-related amygdala activity and increased recruitment of prefrontal brain regions associated with cognitive control processes. Emotion regulation efficacy was assessed via behavioral arousal ratings and fMRI activation elicited by an established experimental paradigm including negative images. Participants were instructed to either simply view emotional pictures or detach themselves from feelings triggered by the stimuli. The sample consisted of 36 predominantly adolescent female AN patients and a pairwise age-matched healthy control group. Behavioral and neuroimaging data analyses indicated a reduction of arousal and amygdala activity during the regulation condition for both patients and controls. However, compared with controls, individuals with AN showed increased activation in the amygdala as well as in the right dorsolateral prefrontal cortex (dlPFC) during the passive viewing of aversive compared with neutral pictures. These results extend previous findings indicative of altered processing of salient emotional stimuli in AN, but do not point to a general deficit in the voluntary regulation of negative emotions. Increased dlPFC activation in AN during passive viewing of negative stimuli is in line with the hypothesis that the disorder may be characterized by excessive self-control. Taken together, the data seem to suggest that reappraisal via detachment may be an effective strategy to reduce negative arousal for individuals with AN.


Assuntos
Anorexia Nervosa/diagnóstico por imagem , Nível de Alerta/fisiologia , Encéfalo/diagnóstico por imagem , Emoções/fisiologia , Adolescente , Adulto , Anorexia Nervosa/psicologia , Mapeamento Encefálico , Criança , Feminino , Neuroimagem Funcional , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Adulto Jovem
18.
Sci Rep ; 7(1): 2724, 2017 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-28578412

RESUMO

Binary enterotoxins Clostridium (C.) botulinum C2 toxin, C. perfringens iota toxin and C. difficile toxin CDT are composed of a transport (B) and a separate non-linked enzyme (A) component. Their B-components mediate endocytic uptake into mammalian cells and subsequently transport of the A-components from acidic endosomes into the cytosol, where the latter ADP-ribosylate G-actin resulting in cell rounding and cell death causing clinical symptoms. Protein folding enzymes, including Hsp90 and peptidyl-prolyl cis/trans isomerases facilitate transport of the A-components across endosomal membranes. Here, we identified Hsp70 as a novel host cell factor specifically interacting with A-components of C2, iota and CDT toxins to facilitate their transport into the cell cytosol. Pharmacological Hsp70-inhibition specifically prevented pH-dependent trans-membrane transport of A-components into the cytosol thereby protecting living cells and stem cell-derived human miniguts from intoxication. Thus, Hsp70-inhibition might lead to development of novel therapeutic strategies to treat diseases associated with bacterial ADP-ribosylating toxins.


Assuntos
ADP Ribose Transferases/metabolismo , Bactérias/metabolismo , Enterotoxinas/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Animais , Chlorocebus aethiops , Proteínas de Choque Térmico HSP70/antagonistas & inibidores , Humanos , Concentração de Íons de Hidrogênio , Ligação Proteica , Células Vero
19.
Genome Announc ; 4(2)2016 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-27081124

RESUMO

Here, we report the draft genome sequence ofClostridium neopropionicumX4 (DSM 3847(T)), a strictly anaerobic bacterium capable of fermenting ethanol and CO2to propionate, acetate, and propanol. The genome consists of a single chromosome (3.19 Mb).

20.
Artigo em Inglês | MEDLINE | ID: mdl-26978378

RESUMO

This paper revisits work on the socio-political amplification of risk, which predicts that those living in developing countries are exposed to greater risk than residents of developed nations. This prediction contrasts with the neoliberal expectation that market driven improvements in working conditions within industrialising/developing nations will lead to global convergence of hazard exposure levels. It also contradicts the assumption of risk society theorists that there will be an ubiquitous increase in risk exposure across the globe, which will primarily affect technically more advanced countries. Reviewing qualitative evidence on the impact of structural adjustment reforms in industrialising countries, the export of waste and hazardous waste recycling to these countries and new patterns of domestic industrialisation, the paper suggests that workers in industrialising countries continue to face far greater levels of hazard exposure than those of developed countries. This view is confirmed when a data set including 105 major multi-fatality industrial disasters from 1971 to 2000 is examined. The paper concludes that there is empirical support for the predictions of socio-political amplification of risk theory, which finds clear expression in the data in a consistent pattern of significantly greater fatality rates per industrial incident in industrialising/developing countries.


Assuntos
Acidentes de Trabalho/estatística & dados numéricos , Países Desenvolvidos/estatística & dados numéricos , Países em Desenvolvimento/estatística & dados numéricos , Desenvolvimento Industrial , Internacionalidade , Exposição Ocupacional/estatística & dados numéricos , Traumatismos Ocupacionais/etiologia , Acidentes de Trabalho/mortalidade , Humanos , Modelos Teóricos , Exposição Ocupacional/efeitos adversos , Traumatismos Ocupacionais/mortalidade , Risco
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