143 research outputs found

    Applying two-photon excitation fluorescence lifetime imaging microscopy to study photosynthesis in plant leaves

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    This study investigates to which extent two-photon excitation (TPE) fluorescence lifetime imaging microscopy can be applied to study picosecond fluorescence kinetics of individual chloroplasts in leaves. Using femtosecond 860 nm excitation pulses, fluorescence lifetimes can be measured in leaves of Arabidopsis thaliana and Alocasia wentii under excitation-annihilation free conditions, both for the F0- and the Fm-state. The corresponding average lifetimes are ~250 ps and ~1.5 ns, respectively, similar to those of isolated chloroplasts. These values appear to be the same for chloroplasts in the top, middle, and bottom layer of the leaves. With the spatial resolution of ~500 nm in the focal (xy) plane and 2 μm in the z direction, it appears to be impossible to fully resolve the grana stacks and stroma lamellae, but variations in the fluorescence lifetimes, and thus of the composition on a pixel-to-pixel base can be observed

    Faecal immunochemical tests (FIT) can help to rule out colorectal cancer in patients presenting in primary care with lower abdominal symptoms:a systematic review conducted to inform new NICE DG30 diagnostic guidance

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    __Background:__ This study has attempted to assess the effectiveness of quantitative faecal immunochemical tests (FIT) for triage of people presenting with lower abdominal symptoms, where a referral to secondary care for investigation of suspected colorectal cancer (CRC) is being considered, particularly when the 2-week criteria are not met. __Methods:__ We conducted a systematic review following published guidelines for systematic reviews of diagnostic tests. Twenty-one resources were searched up until March 2016. Summary estimates were calculated using a bivariate model or a random-effects logistic regression model. __Results:__ Nine studies are included in this review. One additional study, included in our systematic review, was provided as 'academic in confidence' and cannot be described herein. When FIT was based on a single faecal sample and a cut-off of 10 μg Hb/g faeces, sensitivity estimates indicated that a negative result using either the OC-Sensor or HM-JACKarc may be adequate to rule out nearly all CRC; the summary estimate of sensitivity for the OC-Sensor was 92.1%, based on four studies, and the only study of HM-JACKarc to assess the 10 μg Hb/g faeces cut-off reported a sensitivity of 100%. The corresponding specificity estimates were 85.8% (95% CI 78.3-91.0%) and 76.6%, respectively. When the diagnostic criterion was changed to include lower grades of neoplasia, i.e. the target condition included higher risk adenoma (HRA) as well as CRC, the rule-out performance of both FIT assays was reduced. __Conclusions:__ There is evidence to suggest that triage using FIT at a cut-off around 10 μg Hb/g faeces has the potential to correctly rule out CRC and avoid colonoscopy in 75-80% of symptomatic patients. Systematic review registration: PROSPERO 4201603772

    Cross-national comparison of the link between socioeconomic status and emotional and behavioral problems in youths

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    Introduction: In previous longitudinal studies in the US, lower socioeconomic status (SES) was associated with more emotional and behavioral problems. It remains unclear whether these findings can be generalized outside the US, as different countries vary in their health care systems and prevention of psychopathology in youth. Therefore, we studied the same associations in a comparable sample in The Netherlands and directly tested for differences between the US and The Netherlands. Methods: The US (N = 833) and Dutch (N = 708) population samples were followed-up for 9 years. Age at baseline ranged from 8 to 16 years. Parents filled out behavior checklists. Results: Analyses revealed very few differences between the two countries. In both countries, SES predicted syndrome scores and cumulative prevalence rates for internalizing and externalizing problems (withdrawn and aggressive behavior) and for thought and attention Problems. The SES gradient in syndrome scores was stable over time. Only for withdrawn behavior, the gradient was larger in young adulthood. Conclusion: Although the health care systems differ between the US and The Netherl

    Exploring the structure of the N-terminal domain of CP29 with ultrafast fluorescence spectroscopy

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    A high-throughput Förster resonance energy transfer (FRET) study was performed on the approximately 100 amino acids long N-terminal domain of the photosynthetic complex CP29 of higher plants. For this purpose, CP29 was singly mutated along its N-terminal domain, replacing one-by-one native amino acids by a cysteine, which was labeled with a BODIPY fluorescent probe, and reconstituted with the natural pigments of CP9, chlorophylls and xanthophylls. Picosecond fluorescence experiments revealed rapid energy transfer (~20–70 ps) from BODIPY at amino-acid positions 4, 22, 33, 40, 56, 65, 74, 90, and 97 to Chl a molecules in the hydrophobic part of the protein. From the energy transfer times, distances were estimated between label and chlorophyll molecules, using the Förster equation. When the label was attached to amino acids 4, 56, and 97, it was found to be located very close to the protein core (~15 Å), whereas labels at positions 15, 22, 33, 40, 65, 74, and 90 were found at somewhat larger distances. It is concluded that the entire N-terminal domain is in close contact with the hydrophobic core and that there is no loop sticking out into the stroma. Most of the results support a recently proposed topological model for the N-terminus of CP29, which was based on electron-spin-resonance measurements on spin-labeled CP29 with and without its natural pigment content. The present results lead to a slight refinement of that model

    Malnutrition in patients treated for oral or oropharyngeal cancer—prevalence and relationship with oral symptoms: an explorative study

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    This study aimed to assess prevalence of malnutrition after treatment for oral/oropharyngeal cancer and to explore how oral symptoms relate to malnutrition after treatment. In this cross-sectional study, malnutrition (weight loss a parts per thousand yenaEuro parts per thousand 10% in 6 months or a parts per thousand yen5% in 1 month), oral symptoms (EORTC QLQ-H&N35 questionnaire and additional questions to assess chewing problems), dental status, trismus and dietary intake were assessed in 116 adult patients treated for oral/oropharyngeal cancer. Prevalence of malnutrition was 16% (95%CI: 10% to 23%). Prevalence of malnutrition in the period 0-3 months after treatment was significantly higher (25%) than in the periods > 3-12 months (13%) and > 12-36 months after treatment (3%, p = 0.008). Logistic multivariate regression analysis revealed that swallowing problems (p = 0.021) and insufficient protein intake were significantly related to malnutrition (p = 0.016). In conclusion, malnutrition is a considerable problem in patients treated for oral/oropharyngeal cancer, shortly after treatment. Of all oral symptoms, only swallowing problems were significantly related to malnutrition in the period after treatment for oral/oropharyngeal cancer

    National Origin and Behavioural Problems of Toddlers: The Role of Family Risk Factors and Maternal Immigration Characteristics

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    In many societies the prevalence of behavioural problems in school-aged children varies by national origin. We examined the association between national origin and behavioural problems in 1½-year-old children. Data on maternal national origin and the Child Behavior Checklist for toddlers (n = 4943) from a population-based cohort in the Netherlands were used. Children from various non-Dutch backgrounds all had a significantly higher mean behavioural problem score. After adjustment for family risk factors, like family income and maternal psychopathology, the differences attenuated, but remained statistically significant. Non-Dutch mothers with immigration risk factors, such as older age at immigration or no good Dutch language skills, reported significantly more behavioural problems in their offspring. In conclusion, the present study indicated more behavioural problems in immigrant toddlers from various backgrounds. Researchers and policymakers aiming to tackle disparities in behavioural problems should take into account that risks associated with national origin are intertwined with unfavourable family and immigration characteristics

    Depressive symptoms and smoking among young Turkish and Moroccan ethnic minority groups in the Netherlands: a cross-sectional study

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    ABSTRACT: BACKGROUND: Although evidence indicates a strong association between depressive symptoms and smoking among host and migrant adults, less is known about this relationship among young ethnic minority groups in Europe. This paper aims to assess the relationship between depressive symptoms and smoking among young Turkish and Moroccan migrants in the Netherlands. METHODS: Multiple logistic regression analyses was used to analyze cross-sectional data from a sample of 364 Turkish and Moroccan migrants aged 15 to 24 years. The Center for Epidemiologic Studies Depression Scale (CES-D) was used to measure the presence of clinically significant depressive symptoms. Smoking behavior was measured by a number of questions. RESULTS: Of the respondents, 22% were smokers and 33% had depressive symptoms. The prevalence of depressive symptoms was significantly higher in smokers (42.9%) than in nonsmokers (29.5%). Respondents with depressive symptoms had increased odds of smoking even after adjusting for socioeconomic and cultural factors (OR = 2.68, 95% CI = 1.45-4.97). CONCLUSIONS: Depressive symptoms were significantly associated with smoking behavior in young Turkish and Moroccan migrants. In addition to other acknowledged factors, depressive symptoms should also be considered in relation to the smoking behavior of this group. Intervention programs for smoking behavior should take depressive symptoms into account for young Turkish and Moroccan migrant

    The performance of stochastic designs in wellbore drilling operations

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    © 2018, The Author(s). Wellbore drilling operations frequently entail the combination of a wide range of variables. This is underpinned by the numerous factors that must be considered in order to ensure safety and productivity. The heterogeneity and sometimes unpredictable behaviour of underground systems increases the sensitivity of drilling activities. Quite often the operating parameters are set to certify effective and efficient working processes. However, failings in the management of drilling and operating conditions sometimes result in catastrophes such as well collapse or fluid loss. This study investigates the hypothesis that optimising drilling parameters, for instance mud pressure, is crucial if the margin of safe operating conditions is to be properly defined. This was conducted via two main stages: first a deterministic analysis—where the operating conditions are predicted by conventional modelling procedures—and then a probabilistic analysis via stochastic simulations—where a window of optimised operation conditions can be obtained. The outcome of additional stochastic analyses can be used to improve results derived from deterministic models. The incorporation of stochastic techniques in the evaluation of wellbore instability indicates that margins of the safe mud weight window are adjustable and can be extended considerably beyond the limits of deterministic predictions. The safe mud window is influenced and hence can also be amended based on the degree of uncertainty and the permissible level of confidence. The refinement of results from deterministic analyses by additional stochastic simulations is vital if a more accurate and reliable representation of safe in situ and operating conditions is to be obtained during wellbore operations.Published versio
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