The ability to rapidly detect viable pathogens in food is important for public health and food safety reasons. Culture-based detection methods, the traditional means of demonstrating microbial ...viability, tend to be laborious, time consuming and slow to provide results. Several culture-independent methods to detect viable pathogens have been reported in recent years, including both nucleic acid–based (PCR combined with use of cell viability dyes or reverse-transcriptase PCR to detect messenger RNA) and phage-based (plaque assay or phage amplification and lysis plus PCR/qPCR, immunoassay or enzymatic assay to detect host DNA, progeny phages or intracellular components) methods. Some of these newer methods, particularly phage-based methods, show promise in terms of speed, sensitivity of detection and cost compared with culture for food testing. This review provides an overview of these new approaches and their food testing applications, and discusses their current limitations and future prospects in relation to detection of viable pathogens in food.
Key points
• Cultural methods may be ‘gold standard’ for assessing viability of pathogens, but they are too slow.
• Nucleic acid–based methods offer speed of detection but not consistently proof of cell viability.
• Phage-based methods appear to offer best alternative to culture for detecting viable pathogens.
Many tropical rain forest regions are at risk of increased future drought. The net effects of drought on forest ecosystem functioning will be substantial if important ecological thresholds are ...passed. However, understanding and predicting these effects is challenging using observational studies alone. Field-based rainfall exclusion (canopy throughfall exclusion; TFE) experiments can offer mechanistic insight into the response to extended or severe drought and can be used to help improve model-based simulations, which are currently inadequate. Only eight TFE experiments have been reported for tropical rain forests. We examine them, synthesizing key results and focusing on two processes that have shown threshold behavior in response to drought: (1) tree mortality and (2) the efflux of carbon dioxdie from soil, soil respiration. We show that: (a) where tested using large-scale field experiments, tropical rain forest tree mortality is resistant to long-term soil moisture deficit up to a threshold of 50% of the water that is extractable by vegetation from the soil, but high mortality occurs beyond this value, with evidence from one site of increased autotrophic respiration, and (b) soil respiration reaches its peak value in response to soil moisture at significantly higher soil moisture content for clay-rich soils than for clay-poor soils. This first synthesis of tropical TFE experiments offers the hypothesis that low soil moisture–related thresholds for key stress responses in soil and vegetation may prove to be widely applicable across tropical rain forests despite the diversity of these forests.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary Hypothyroidism is a common condition of thyroid hormone deficiency, which is readily diagnosed and managed but potentially fatal in severe cases if untreated. The definition of hypothyroidism ...is based on statistical reference ranges of the relevant biochemical parameters and is increasingly a matter of debate. Clinical manifestations of hypothyroidism range from life threatening to no signs or symptoms. The most common symptoms in adults are fatigue, lethargy, cold intolerance, weight gain, constipation, change in voice, and dry skin, but clinical presentation can differ with age and sex, among other factors. The standard treatment is thyroid hormone replacement therapy with levothyroxine. However, a substantial proportion of patients who reach biochemical treatment targets have persistent complaints. In this Seminar, we discuss the epidemiology, causes, and symptoms of hypothyroidism; summarise evidence on diagnosis, long-term risk, treatment, and management; and highlight future directions for research.
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Robust and efficient methylene blue (MB) adsorbent was prepared based on starch/cellulose nanowhiskers hydrogel composite. Maximum MB adsorption capacity of ∼2050mgperg of dried ...hydrogel was obtained with the composite at 5wt.% of cellulose nanowhiskers and at pH 5. Adsorption capacity varied from 1450mg/g to 2050mg/g with increasing the initial MB concentration from 1500mg/L to 2500mg/L, respectively. For all the concentrations studied ca. 90% of MB was removed by the adsorbent. Optimal conditions were obtained at pH⩾5 due to the generation of negatively charged groups (COO−) in the adsorbent, which can strongly interact with the positive charges from MB. The main advantage of this system over other reported adsorbents, besides the fact of being synthesized from biodegradable polymers (starch and cellulose), is its fast adsorption kinetics that follows the pseudo-second order model, which is based on chimisorption phenomenon. Saturation condition was reached as fast as 1h of experiments owing to the formation of an adsorbed MB monolayer as suggested by the Langmuir isotherm model. Desorption experiments showed 60wt.% of MB loaded can be removed from the adsorbent by immersing it in a pH 1 solution, showing its feasibility to be reused. Therefore, starch/cellulose nanowhiskers hydrogel composite presents outstanding capacity to be employed in the remediation of MB contaminated wastewaters.
Magnetic freezing is nowadays established as a commercial reality mainly oriented towards the food market. According to advertisements, magnetic freezing is able to generate tiny ice crystals ...throughout the frozen product, prevent cell destruction, and preserve the quality of fresh food intact after thawing. If all these advantages were true, magnetic freezing would represent a significant advance in freezing technology, not only for food preservation, but also for cryopreservation of biological specimens such as cells, tissues, and organs. Magnetic fields (MFs) are supposed to act directly on water by orientating, vibrating, and/or spinning molecules to prevent them from clustering and, thus, to promote supercooling. However, many doubts exist about the real effects of MFs on freezing and the science behind the potential mechanisms involved. To provide a basis for extending the understanding of magnetic freezing, this paper presents a critical review of the materials published in the literature up to now, including both patents and experimental results. After examining the information available, it was not possible to discern whether MFs have an appreciable effect on supercooling, freezing kinetics, ice crystals, quality, and/or viability of the frozen products. Experiments described in the literature frequently fail to identify and/or control all the factors that can play a role in magnetic freezing. Moreover, many of the comparisons between magnetic and conventional freezing are not correctly designed to draw valid conclusions, and wide ranges of MF intensities and frequencies are unexplored. Therefore, more rigorous experimentation and further evidence are needed to confirm or reject the efficacy of MFs in improving the quality of frozen products.
High-throughput (HTP) plant phenotyping approaches are developing rapidly and are already helping to bridge the genotype–phenotype gap. However, technologies should be developed beyond current ...physico-spectral evaluations to extend our analytical capacities to the subcellular level. Metabolites define and determine many key physiological and agronomic features in plants and an ability to integrate a metabolomics approach within current HTP phenotyping platforms has huge potential for added value. While key challenges remain on several fronts, novel technological innovations are upcoming yet under-exploited in a phenotyping context. In this review, we present an overview of the state of the art and how current limitations might be overcome to enable full integration of metabolomics approaches into a generic phenotyping pipeline in the near future.
Advanced facilities for automated phenotyping have already been established but there is a growing demand to integrate additional sensing modalities to allow deep phenotyping. Ongoing developments in automated (noninvasive) metabolomics show great promise.Approaches to online volatile metabolomics are progressing well although nonvolatile analyses continue to pose significant challenges in terms of practicality and cost.Integration of multiple sensors such as optical molecular spectroscopy, imaging, and mass spectroscopy in automated phenotyping facilities shall provide enhanced complementary insights into the dynamics of plant phenotype.In the domains of metabolomics, chemometrics, transcriptomics, and imaging, recent data fusion techniques such as statistical multiblock data analysis, network and pathway modelling, and deep learning are beginning to realize systems-type approaches.
The fate of tropical forests under future climate change is dependent on the capacity of their trees to adjust to drier conditions. The capacity of trees to withstand drought is likely to be ...determined by traits associated with their hydraulic systems. However, data on whether tropical trees can adjust hydraulic traits when experiencing drought remain rare. We measured plant hydraulic traits (e.g. hydraulic conductivity and embolism resistance) and plant hydraulic system status (e.g. leaf water potential, native embolism and safety margin) on >150 trees from 12 genera (36 species) and spanning a stem size range from 14 to 68 cm diameter at breast height at the world's only long‐running tropical forest drought experiment. Hydraulic traits showed no adjustment following 15 years of experimentally imposed moisture deficit. This failure to adjust resulted in these drought‐stressed trees experiencing significantly lower leaf water potentials, and higher, but variable, levels of native embolism in the branches. This result suggests that hydraulic damage caused by elevated levels of embolism is likely to be one of the key drivers of drought‐induced mortality following long‐term soil moisture deficit. We demonstrate that some hydraulic traits changed with tree size, however, the direction and magnitude of the change was controlled by taxonomic identity. Our results suggest that Amazonian trees, both small and large, have limited capacity to acclimate their hydraulic systems to future droughts, potentially making them more at risk of drought‐induced mortality.
The fate of tropical forests under future climate change is dependent on the capacity of their trees to adjust to drier conditions. Following 15 years of experimentally imposed moisture deficit, Amazon trees showed no adjustment in their hydraulic traits to moisture deficit. This failure to adjust resulted in these drought‐stressed trees experiencing significantly reduced water potential and increased hydraulic failure. Both, small and large trees equally, could not adapt to moisture deficit. Our results suggest Amazon trees have a limited capacity to adjust to future droughts.
Despite its widespread use, RNA-seq is still too laborious and expensive to replace RT-qPCR as the default gene expression analysis method. We present a novel approach, BRB-seq, which uses early ...multiplexing to produce 3' cDNA libraries for dozens of samples, requiring just 2 hours of hands-on time. BRB-seq has a comparable performance to the standard TruSeq approach while showing greater tolerance for lower RNA quality and being up to 25 times cheaper. We anticipate that BRB-seq will transform basic laboratory practice given its capacity to generate genome-wide transcriptomic data at a similar cost as profiling four genes using RT-qPCR.
We investigated the factors associated with no dental visit within the last two years by adolescents in the state of São Paulo, Brazil, by using data from the Oral Health Conditions of São Paulo ...state population Project (SBSP-2015) conducted in 2015.
This was a cross-sectional epidemiological study with a representative sample of adolescents aged 15 to higher years residing in São Paulo State. The examiners were calibrated and dental visits were measured categorically as 1- Less than 1 year, 2- One to two years, 3 - Three years or more, 4- I have never visited the dentist. Based on the literature we dichotomized the outcome in two groups: response 1 plus 2 against response 3 plus 4. Then, Multilevel Poisson Regression (MPR) was used to estimate the prevalence ratios of last dental visit three years or had never been to a dentist by adolescents compared with those who had visited the dentist within the past two years, with contextual variables as the distal level; sociodemographic variables, mesial; and individual variables, proximal level.
A high percentage of adolescents (84.9%) reported visiting the dentist in the last 2 years. Whereas, 626 (11.6%) had not visited the dentist for over 3 years and 188 (3.4%) had never been. A significantly higher proportion of females than males reported visiting the dentist in the past 2 years (p = 0.003). The oral and dental condition was reported as satisfactory by 4,350 respondents (80.6%), and when they accessed the health service, 2,286 (42.3%) went to the public service. Lower mean family income (1.62PR;95%CI;1.36-1.94); ≥ 1,000 inhabitant/Dental Surgeons (1.25PR;95%IC;1.03-1.56);male (1.26PR;95%CI; 1.11-1.43) non-Caucasian ethnicity (Mulatto:1.30PR;95%CI;1.13-1.50 and Black:1.58PR;95%CI;1.29-1.93); dissatisfaction with the oral health condition (1.20PR;95%CI;1.01-1.45),last visit to the public service versus private service (2.26PR; 95%CI;1.91-2.65) and presenting with periodontal disease in the form of dental calculus as the worst situation (1.38PR; 95%CI; 1.16-1.53) were associated with last visit to the dentist.
A high proportion of adolescents had visited the dentist in the last two years. No dental visit within the last two years by adolescents were associated with contextual, health care system, sociodemographic, personal and oral health status, demonstrating that this is a complex phenomenon. Actions to promote regular dental visits by adolescents in Brazil should take these factors into consideration.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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