Impact of soil moisture stress during the silk emergence and grain-filling in maize

Suboptimal soil moisture during the growing season often limits maize growth and yield. However, the growth stage-specific responses of maize to soil moisture regimes have not been thoroughly investigated. This study investigated the response of maize to five different soil moisture regimes, that are, 0.25, 0.20, 0.15, 0.10, and 0.05 m3  m-3 volumetric water content (VWC), during flowering and grain-filling stages. Sub-optimal soil moisture at the flowering and grain-filling stages reduced ear leaf stomatal conductance by 73 and 64%, respectively. An increase in stress severity caused significant reductions in ear leaf chlorophyll content and greenness-associated vegetation indices across growth stages. Fourteen days of soil moisture stress during flowering delayed silk emergence, reduced silk length (19%), and silk fresh weight (34%). Furthermore, sub-optimal soil moisture caused a significant reduction in both kernel number (53%) and weight (54%). Soil moisture stress at the flowering had a direct impact on kernel number and an indirect effect on kernel weight. During grain-filling, disruption of ear leaf physiology resulted in a 34% decrease in kernel weight and a 43% decrease in kernel number. Unlike grain-filling, treatments at the flowering significantly reduced kernel starch (3%) and increased protein by 29%. These findings suggest that developing reproductive stage stress-tolerant hybrids with improved resilience to soil moisture stress could help reduce the yield gap between irrigated and rainfed maize.

Phenological stage and vegetation index for predicting corn yield under rainfed environments

Uncrewed aerial systems (UASs) provide high temporal and spatial resolution information for crop health monitoring and informed management decisions to improve yields. However, traditional in-season yield prediction methodologies are often inconsistent and inaccurate due to variations in soil types and environmental factors. This study aimed to identify the best phenological stage and vegetation index (VI) for estimating corn yield under rainfed conditions. Multispectral images were collected over three years (2020-2022) during the corn growing season and over fifty VIs were analyzed. In the three-year period, thirty-one VIs exhibited significant correlations (r ≥ 0.7) with yield. Sixteen VIs were significantly correlated with the yield at least for two years, and five VIs had a significant correlation with the yield for all three years. A strong correlation with yield was achieved by combining red, red edge, and near infrared-based indices. Further, combined correlation and random forest an alyses between yield and VIs led to the identification of consistent and highest predictive power VIs for corn yield prediction. Among them, leaf chlorophyll index, Medium Resolution Imaging Spectrometer (MERIS) terrestrial chlorophyll index and modified normalized difference at 705 were the most consistent predictors of corn yield when recorded around the reproductive stage (R1). This study demonstrated the dynamic nature of canopy reflectance and the importance of considering growth stages, and environmental conditions for accurate corn yield prediction.

Effects of fine grinding on mid-infrared spectroscopic analysis of plant leaf nutrient content

Fourier transform mid infrared (FT-MIR) spectroscopy combined with modeling techniques has been studied as a useful tool for multivariate chemical analysis in agricultural research. A drawback of this method is the sample preparation requirement, in which samples must be dried and fine ground for accurate model calibrations. For research involving large sample sets, this may dramatically increase the time and cost of analysis. This study investigates the effect of fine grinding on model performance using leaf tissue from a variety of crop species. Dried leaf samples (N = 300) from various environmental conditions were obtained with data on 11 nutrients measured using chemical methods. The samples were scanned with attenuated total reflectance (ATR) and diffuse reflectance (DRIFT) FT-MIR techniques. Scanning was repeated after fine grinding for 2, 5, and 10 min. The spectra were analyzed for the 11 nutrients using partial least squares regression with a 75%/25% split for calibration and validation and repeated for 50 iterations. All analytes except for boron, iron, and zinc were well-modeled (average R² > 0.7), with higher R² values on ATR spectra. The 5 min level of fine grinding was found to be most optimal considering overall model performance and sample preparation time.

Resilience of soybean cultivars to drought stress during flowering and early-seed setting stages

Drought stress during the reproductive stage and declining soybean yield potential raise concerns about yield loss and economic return. In this study, ten cultivars were characterized for 20 traits to identify reproductive stage (R1-R6) drought-tolerant soybean. Drought stress resulted in a marked reduction (17%) in pollen germination. The reduced stomatal conductance coupled with high canopy temperature resulted in reduced seed number (45%) and seed weight (35%). Drought stress followed by rehydration increased the hundred seed weight at the compensation of seed number. Further, soybean oil decreased, protein increased, and cultivars responded differently under drought compared to control. In general, cultivars with high tolerance scores for yield displayed lower tolerance scores for quality content and vice versa. Among ten cultivars, LS5009XS and G4620RX showed maximum stress tolerance scores for seed number and seed weight. The observed variability in leaf reflectance properties and their relationship with physiological or yield components suggested that leaf-level sensing information can be used for differentiating drought-sensitive soybean cultivars from tolerant ones. The study led to the identification of drought-resilient cultivars/promising traits which can be exploited in breeding to develop multi-stress tolerant cultivars.

Sweetpotato cultivars responses to interactive effects of warming, drought, and elevated carbon dioxide

Plants are sensitive to changes projected in climates, such as elevated carbon dioxide (eCO₂), high temperature (T), and drought stress (DS), which affect crop growth, development, and yield. These stresses, either alone or in combination, affect all aspects of sweetpotato plant growth and development, including storage root development and yield. We tested three sweetpotato cultivars (Beauregard, Hatteras, and LA1188) responses to eight treatments (Control, DS, T, eCO₂, DS + T, T + eCO_2, DS + eCO_2, DS + T + eCO₂). All treatments were imposed 36 days after transplanting (DAP) and continued for 47 days. Treatments substantially affected gas exchange, photosynthetic pigments, growth, and storage root components. Cultivars differed considerably for many of the measured parameters. The most significant negative impact of DS was recorded for the shoot and root weights. The combination of DS + T had a significant negative effect on storage root parameters. eCO₂ alleviated some of the damaging effects of DS and high T in sweetpotato. For instance, eCO₂ alone or combined with DS increased the storage root weights by 22% or 42% across all three cultivars, respectively. Based on the stress response index, cultivar "Hatteras" was most tolerant to individual and interactive stresses, and "LA 1188" was sensitive. Our findings suggest that eCO₂ negates the negative impact of T or DS on the growth and yield of sweetpotato. We identified a set of individual and interactive stress-tolerant traits that can help select stress cultivars or breed new lines for future environments.

Proteomic analysis response of rice (Oryza sativa) leaves to ultraviolet-B radiation stress

Rice (Oryza sativa) is a human staple food and serves as a model organism for genetic and molecular studies. Few studies have been conducted to determine the effects of ultraviolet-B (UV-B) stress on rice. UV-B stress triggers morphological and physiological changes in plants. However, the underlying mechanisms governing these integrated responses are unknown. In this study, we conducted a proteomic response of rice leaves to UV-B stress using two-dimensional gel electrophoresis and identified the selected proteins by mass spectrometry analysis. Four levels of daily biologically effective UV-B radiation intensities were imposed to determine changes in protein accumulation in response to UV-B stress: 0 (control), 5, 10, and 15 kJ m^-2 d^-1in two cultivars, i.e., IR6 and REX. To mimic the natural environment, we conducted this experiment in Sunlit Soil-Plant-Atmosphere-Research (SPAR) chambers. Among the identified proteins, 11% of differentially expressed proteins were found in both cultivars. In the Rex cultivar, only 45% of proteins are differentially expressed, while only 27.5% were expressed in IR6. The results indicate that REX is more affected by UV-B stress than IR6 cultivars. The identified protein TSJT1 (spot 16) in both cultivars plays a crucial role in plant growth and development during stress treatment. Additionally, we found that UV-B stress altered many antioxidant enzymes associated with redox homeostasis and cell defense response. Another enzyme, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), has been identified as spot 15, which plays an essential role in glycolysis and cellular energy production. Another vital protein identified is glycosyl hydrolase (GH) as spot 9, which catalyzes the hydrolysis of glycosidic bonds in cell wall polymers and significantly affects cell wall architecture. Some identified proteins are related to photosynthesis, protein biosynthesis, signal transduction, and stress response. The findings of our study provide new insights into understanding how rice plants are tailored to UV-B stress via modulating the expression of UV-B responsive proteins, which will help develop superior rice breeds in the future to combat UV-B stress. Data are available via ProteomeXchange with identifier PXD032163.

Effects of drought and heat stresses during reproductive stage on pollen germination, yield, and leaf reflectance properties in maize (Zea mays L.)

Drought and heat stresses are the major abiotic stress factors detrimental to maize (Zea mays L.) production. Much attention has been directed toward plant responses to heat or drought stress. However, maize reproductive stage responses to combined heat and drought remain less explored. Therefore, this study aimed to quantify the impact of optimum daytime (30°C, control) and warmer daytime temperatures (35°C, heat stress) on pollen germination, morpho-physiology, and yield potential using two maize genotypes ("Mo17" and "B73") under contrasting soil moisture content, that is, 100% and 40% irrigation during flowering. Pollen germination of both genotypes decreased under combined stresses (42%), followed by heat stress (30%) and drought stress (19%). Stomatal conductance and transpiration were comparable between control and heat stress but significantly decreased under combined stresses (83% and 72%) and drought stress (52% and 47%) compared with the control. Genotype "Mo17" reduced its green leaf area to minimize the water loss, which appears to be one of the adaptive strategies of "Mo17" under stress conditions. The leaf reflectance of both genotypes varied across treatments. Vegetation indices associated with pigments (chlorophyll index of green, chlorophyll index of red edge, and carotenoid index) and plant health (normalized difference red-edge index) were found to be highly sensitive to drought and combined stressors than heat stress. Combined drought and heat stresses caused a significant reduction in yield and yield components in both Mo17 (49%) and B73 (86%) genotypes. The harvest index of genotype "B73" was extremely low, indicating poor partitioning efficiency. At least when it comes to "B73," the cause of yield reduction appears to be the result of reduced sink number rather than the pollen and source size. To the best of our awareness, this is the first study that showed how the leaf-level spectra, yield, and quality parameters respond to the short duration of independent and combined stresses during flowering in inbred maize. Further studies are required to validate the responses of potential traits involving diverse maize genotypes under field conditions. This study suggests the need to develop maize with improved tolerance to combined stresses to sustain production under increasing temperatures and low rainfall conditions.

Low- and High-Temperature Phenotypic Diversity of Brassica carinata Genotypes for Early-Season Growth and Development

Temperature is a major abiotic stress factor limiting plant growth and development during the early developmental stage. Information on carinata (Brassica carinata A. Braun) traits response to low and high temperatures is necessary for breeding or selecting genotypes suited for specific ecoregions, which is limited. In the present study, 12 carinata genotypes were evaluated under low (17/09°C), optimum (22/14°C), and high (27/19°C) day/night temperatures at the early developmental stage. This study quantified temperature effects on several physiological and morphological characteristics of 12-advanced carinata lines. High-temperature plants decreased (15%) the accumulation of flavonoids and increased the nitrogen balance index by 25%. Low-temperature treatment significantly inhibited the aboveground (plant height, leaf area, number, and shoot weight) and root (length, surface area, and weight) traits. Across all genotypes, the shoot weight decreased by 55% and the root weight by 49% under low temperature. On the other hand, the maximum proportion of biomass was partitioned to roots under low temperature than at the high temperature. A poor relationship (r ² = 0.09) was found between low- and high-temperature indices, indicating differences in trait responses and tolerance mechanisms. AX17004 and AX17009 with higher root to shoot ratios might be suitable for late planting windows or regions with low-temperature spells. The two genotypes (AX17015 and AX17005) accumulated higher biomass under low- and high-temperature treatments can be used for planting in later summer or early winter. The identified low- and high-temperature stress-tolerant carinata genotypes could be a valuable resource for increasing stress tolerance during the early developmental stage.

Broad-spectrum cyclic boronate β-lactamase inhibitors featuring an intramolecular prodrug for oral bioavailability

Early efforts to broaden the spectrum and potency of cyclic boronic acid β-lactamase inhibitor vaborbactam included a series of 7-membered ring boronates. Exploration of stereoisomers and incorporation of heteroatoms allowed identification of the all-carbon cyclic boronate with substituents trans as the preferred core structure, showing inhibition of Class A and C enzymes. Crystal structures of one analog bound to important β-lactamase enzymes were obtained. When isolated under acidic conditions, these compounds spontaneously formed a neutral cyclic anhydride (intramolecular prodrug) which was shown to have much-improved oral bioavailability (52-69%) compared to the ring-opened carboxylate salt (9%).

Morpho-Physiological, Yield, and Transgenerational Seed Germination Responses of Soybean to Temperature

Temperature is the primary factor affecting the morpho-physiological, developmental, and yield attributes of soybean. Despite several temperature and soybean studies, functional relationships between temperature and soybean physiology and yield components are limited. An experiment was conducted to determine the optimum temperature for soybean gas exchange and yield components using indeterminate (Asgrow AG5332, AG) and determinate (Progeny P5333 RY, PR) growth habit cultivars. Plants grown outdoors were exposed to 5 day/night temperature treatments, 21/13, 25/17, 29/21, 33/25, and 37°C/29°C, from flowering to maturity using the sunlit plant growth chambers. Significant temperature and cultivar differences were recorded among all measured parameters. Gas exchange parameters declined with increasing temperature treatments during the mid-pod filling stage, and quadratic functions best described the response. The optimum temperature for soybean pod weight, number, and seed number was higher for AG than PR, indicating greater high-temperature tolerance. Soybean exposed to warmer parental temperature (37°C/29°C) during pod filling decreased significantly the transgenerational seed germination when incubated at 18, 28, and 38°C. Our findings suggest that the impact of temperature during soybean development is transferable. The warmer temperature has adverse transgenerational effects on seed germination ability. Thus, developing soybean genotypes tolerant to high temperatures will help growers to produce high-yielding and quality beans. The quantified temperature, soybean physiology, and yield components-dependent functional algorithms would be helpful to develop adaptation strategies to offset the impacts of extreme temperature events associated with future climate change.

Selection of QPX7831, an Orally Bioavailable Prodrug of Boronic Acid β-Lactamase Inhibitor QPX7728

In recognition of the need for effective oral therapies to treat Gram-negative bacterial infections, efforts were directed toward identifying an oral prodrug of β-lactamase inhibitor clinical candidate QPX7728. Seventeen prodrugs were synthesized; key properties investigated were rates of cleavage to the active form in vitro, pharmacokinetics across species, and crystallinity. Compound 5-Na (QPX7831 Sodium) emerged with optimal properties across all key attributes.

Developing Functional Relationships between Soil Waterlogging and Corn Shoot and Root Growth and Development

Short- and long-term waterlogging conditions impact crop growth and development, preventing crops from reaching their true genetic potential. Two experiments were conducted using a pot-culture facility to better understand soil waterlogging impacts on corn growth and development. Two corn hybrids were grown in 2017 and 2018 under ambient sunlight and temperature conditions. Waterlogging durations of 0, 2, 4, 6, 8, 10, 12, and 14 days were imposed at the V2 growth stage. Morphological (growth and development) and pigment estimation data were collected 15 days after treatments were imposed, 23 days after sowing. As waterlogging was imposed, soil oxygen rapidly decreased until reaching zero in about 8-10 days; upon the termination of the treatments, the oxygen levels recovered to the level of the 0 days treatment within 2 days. Whole-plant dry weight declined as the waterlogging duration increased, and after 2 days of waterlogging, a 44% and 27% decline was observed in experiments 1 and 2, respectively. Leaf area and root volume showed an exponential decay similar to the leaf and root dry weight. Leaf number and plant height were the least sensitive measured parameters and decreased linearly in both experiments. Root forks were the most sensitive parameter after 14 days of waterlogging in both experiments, declining by 83% and 80% in experiments 1 and 2, respectively. The data from this study improve our understanding of how corn plants react to increasing durations of waterlogging. In addition, the functional relationships generated from this study could enhance current corn simulation models for field applications.

Alterations in the leaf lipidome of Brassica carinata under high-temperature stress

BACKGROUND

Brassica carinata (A) Braun has recently gained increased attention across the world as a sustainable biofuel crop. B. carinata is grown as a summer crop in many regions where high temperature is a significant stress during the growing season. However, little research has been conducted to understand the mechanisms through which this crop responds to high temperatures. Understanding traits that improve the high-temperature adaption of this crop is essential for developing heat-tolerant varieties. This study investigated lipid remodeling in B. carinata in response to high-temperature stress. A commercial cultivar, Avanza 641, was grown under sunlit-controlled environmental conditions in Soil-Plant-Atmosphere-Research (SPAR) chambers under optimal temperature (OT; 23/15°C) conditions. At eight days after sowing, plants were exposed to one of the three temperature treatments [OT, high-temperature treatment-1 (HT-1; 33/25°C), and high-temperature treatment-2 (HT-2; 38/30°C)]. The temperature treatment period lasted until the final harvest at 84 days after sowing. Leaf samples were collected at 74 days after sowing to profile lipids using electrospray-ionization triple quadrupole mass spectrometry.

RESULTS

Temperature treatment significantly affected the growth and development of Avanza 641. Both high-temperature treatments caused alterations in the leaf lipidome. The alterations were primarily manifested in terms of decreases in unsaturation levels of membrane lipids, which was a cumulative effect of lipid remodeling. The decline in unsaturation index was driven by (a) decreases in lipids that contain the highly unsaturated linolenic (18:3) acid and (b) increases in lipids containing less unsaturated fatty acids such as oleic (18:1) and linoleic (18:2) acids and/or saturated fatty acids such as palmitic (16:0) acid. A third mechanism that likely contributed to lowering unsaturation levels, particularly for chloroplast membrane lipids, is a shift toward lipids made by the eukaryotic pathway and the channeling of eukaryotic pathway-derived glycerolipids that are composed of less unsaturated fatty acids into chloroplasts.

CONCLUSIONS

The lipid alterations appear to be acclimation mechanisms to maintain optimal membrane fluidity under high-temperature conditions. The lipid-related mechanisms contributing to heat stress response as identified in this study could be utilized to develop biomarkers for heat tolerance and ultimately heat-tolerant varieties.

Duration and frequency of drainage and flooding events interactively affect soil biogeochemistry and N flux in subtropical peat soils

With the demand for restoration and future prediction of climate change effects, subtropical peatlands are expected to be subjected to hydrologic regimes with variable duration and frequency of drained and flooded conditions, but knowledge of their interactive effects on soil biogeochemistry and emission of greenhouse gases including nitrous oxide (N₂O) is largely limited. The objective of this study was to investigate how the duration and frequency of drainage and flooding events interactively influence soil biogeochemical properties and denitrification and related net N₂O production rates following rewetting. Surface soils are susceptible to different hydrologic regimes. Significantly higher pH, extractable organic carbon (ext. OC), ammonium (NH₄⁺-N), denitrification enzyme activity (DEA), but lower nitrate (NO₃^--N), microbial biomass C and N were observed when the peat soils were under flooded conditions compared to drained conditions. Two-week and four-week drainage or flooding duration did not result in statistically significant differences in soil biogeochemical properties. A 24-week prolonged drainage led to an accumulation of NO₃^--N and a significantly lower pH. Soil microbial biomass and fungal:bacterial abundance likely increased with the frequency of drainage-flooding cycles. Significant differences in denitrification and net N₂O production rates following reflooding were mainly found in the surface soils. Structural equation modeling indicated that hydroperiod and water-filled pore space (WFPS) prior to reflooding is likely to control denitrification and net N₂O production through its regulation of NO₃^--N and activity of microorganisms involved in denitrification while higher drainage-flooding frequency decreases the availability of organic C and NO₃^--N for denitrification. Our results also suggest high NO₃^--N and low pH within peat soils caused by prolonged drainage likely leads to a significant N₂O emission pulse following reflooding. For peat soils subjected to frequent drainage-flooding cycles, N₂O emission pulses following reflooding would decrease with time, attributing to the loss of substrates for denitrification.

Soil phosphorus forms and storage in stormwater treatment areas of the Everglades: Influence of vegetation and nutrient loading

Stormwater treatment areas (STAs) are an integral component of the Everglades restoration strategies to reduce phosphorus (P) loads from adjacent agricultural and urban areas. The overall objective of this study was to determine the forms and distribution of P in floc and soils along the flow-path of two parallel flow-ways (FWs) in STA-2 with emergent aquatic vegetation (EAV) and submerged aquatic vegetation (SAV), respectively, to assess their stability and potential for long term storage. In EAV high organic matter accretion supported low bulk density and high P concentrations in floc and soil, while high mineral matter accretion in SAV resulted in high bulk density and low P concentrations. Approximately 25-30% of the total P is identified as highly reactive P (HRP) pools, 50-60% in moderately reactive P (RP) forms, and 15-20% in the non-reactive P (NRP) pool. Within HRP and RP pools, a large proportion of P in the SAV areas was inorganic while organic P was more dominant in the EAV areas. Enrichment of total P (especially in HRP and RP pools) found in the upstream areas of both FWs resulted from the P loading into FWs over time, and the surplus P conditions can potentially support flux into the water column. In EAV FW, approximately 45% of the P retained was recovered in floc and RAS and remaining was possibly retained in the above and below ground biomass and incorporated into subsurface soils. In SAV FW, all of the P retained was recovered in floc and soils suggesting P retention in plants was not significant. For STAs to continue to function effectively and meet the desired outflow TP concentrations, management strategies should be aimed to promote P limiting conditions within the system to avoid release of P from floc and soils to water column and potential downstream transport.

Drought stress has transgenerational effects on soybean seed germination and seedling vigor

Effects of environmental stressors on the parent may be transmitted to the F1 generation of plants that support global food, oil, and energy production for humans and animals. This study was conducted to determine if the effects of drought stress on parental soybean plants are transmitted to the F1 generation. The germination and seedling vigor of F1 soybean whose maternal parents, Asgrow AG5332 and Progeny P5333RY, were exposed to soil moisture stress, that is, 100, 80, 60, 40, and 20% replacement of evapotranspiration (ET) during reproductive growth, were evaluated under controlled conditions. Pooled over cultivars, effects of soil moisture stress on the parents caused a reduction in the seed germination rate, maximum seed germination, and overall seedling performance in the F1 generation. The effect of soil moisture stress on the parent environment induced seed quality that carried on the F1 generation seed gemination and seedling traits under optimum conditions and further exasperated when exposed to increasing levels of drought stress. Results indicate that seed weight and storage reserve are key factors positively associated with germination traits and seedling growth. Our data confirm that the effects of soil moisture stress on soybean are transferable, causing reduced germination, seedling vigor, and seed quality in the F1 generation. Therefore, optimal water supply during soybean seed formation period may be beneficial for seed producers in terms of optimizing seed quality and vigor characteristics of commodity seed.

Evaluating rice for salinity using pot-culture provides a systematic tolerance assessment at the seedling stage

BACKGROUND

Rice (Oryza sativa L.) is one of the major staple food crops consumed globally. However, rice production is severely affected by high salinity levels, particularly at the seedling stage. A good solution would be the development of an efficient screening methodology to identify genotypes possessing genes for salt tolerance.

RESULT

A new salinity tolerance screening technique using rice seedlings in pot-culture was tested. This method controls soil heterogeneity by using pure sand as a growth medium and minimizes unexpected extreme weather conditions with a movable shelter. Seventy-four rice genotypes were screened at three salinity treatments including high salt stress (electrical conductivity (EC) 12 dSm^- 1), moderate salt stress (EC 6 dSm^- 1), and control (no salt stress), imposed 1 week after emergence. Several shoot and root morpho-physiological traits were measured at 37 days after sowing. A wide range of variability was observed among genotypes for measured traits with root traits being identified as the best descriptors for tolerance to salt stress conditions. Salt stress response indices (SSRI) were used to classify the 74 rice genotypes; 7 genotypes (9.46%) were identified as salt sensitive, 27 (36.48%) each as low and moderately salt tolerant, and 13 (17.57%) as highly salt tolerant. Genotypes FED 473 and IR85427 were identified as the most salt tolerant and salt sensitive, respectively. These results were further confirmed by principal component analysis (PCA) for accuracy and reliability.

CONCLUSION

Although tolerant genotypes still need to be confirmed in field studies and tolerance mechanisms identified at the molecular level, information gained from this study could help rice breeders and other scientists to accelerate breeding by selecting appropriate donor parents, progenies and potential genotypes at early growth stages necessary for salinity tolerance research.

Evaluating rice for salinity using pot-culture provides a systematic tolerance assessment at the seedling stage

BACKGROUND

Rice (Oryza sativa L.) is one of the major staple food crops consumed globally. However, rice production is severely affected by high salinity levels, particularly at the seedling stage. A good solution would be the development of an efficient screening methodology to identify genotypes possessing genes for salt tolerance.

RESULT

A new salinity tolerance screening technique using rice seedlings in pot-culture was tested. This method controls soil heterogeneity by using pure sand as a growth medium and minimizes unexpected extreme weather conditions with a movable shelter. Seventy-four rice genotypes were screened at three salinity treatments including high salt stress (electrical conductivity (EC) 12 dSm^- 1), moderate salt stress (EC 6 dSm^- 1), and control (no salt stress), imposed 1 week after emergence. Several shoot and root morpho-physiological traits were measured at 37 days after sowing. A wide range of variability was observed among genotypes for measured traits with root traits being identified as the best descriptors for tolerance to salt stress conditions. Salt stress response indices (SSRI) were used to classify the 74 rice genotypes; 7 genotypes (9.46%) were identified as salt sensitive, 27 (36.48%) each as low and moderately salt tolerant, and 13 (17.57%) as highly salt tolerant. Genotypes FED 473 and IR85427 were identified as the most salt tolerant and salt sensitive, respectively. These results were further confirmed by principal component analysis (PCA) for accuracy and reliability.

CONCLUSION

Although tolerant genotypes still need to be confirmed in field studies and tolerance mechanisms identified at the molecular level, information gained from this study could help rice breeders and other scientists to accelerate breeding by selecting appropriate donor parents, progenies and potential genotypes at early growth stages necessary for salinity tolerance research.

Soybean seed physiology, quality, and chemical composition under soil moisture stress

Soybean seed quality is often determined by its constituents which are important to sustain overall nutritional aspects. The objective of this study was to investigate the effects of soil moisture stress during reproductive stage on seed quality and composition. Plants were subjected to five levels of soil moisture stresses at flowering, and yield and quality traits were examined at maturity. Seed protein, palmitic and linoleic acids, sucrose, raffinose, stachyose, N, P, K, and Ca significantly decreased whereas oil, stearic, oleic and linolenic acids, Fe, Mg, Zn, Cu, and B increased in response to soil moisture deficiency. The relationship between seed protein and oil was negatively correlated. The changes in seed constituents could be due to changes in nutrient accumulation and partitioning in soybean seeds under water stress. This information suggests the requirement of adequate soil moisture during flowering and seed formation stages to obtain the higher nutritional value of soybean seeds.

Influence of select bioenergy by-products on soil carbon and microbial activity: A laboratory study

Concerns about the negative impacts of crop biomass removal on soil ecological functions have led to questioning the long-term sustainability of bioenergy production. To offset this potential negative impact, use of organic C rich by-products from the bioenergy industries have been proposed as a means to replenish soil C in degraded soils. However, the impact of these by-products application on soil carbon dynamics is not fully understood. We measured biogeochemical changes in soil organic C following a three-year field application of two by-products, biochar (BC) and fermentation-by product (FBP), of bioenergy industry processes in an elephant grass [Pennisetum purpureum (L.) Schum.] field. There was a significant increase in overall soil organic C (SOC) observed in BC (270%) treated plots, however the higher labile SOC (51%) content was present in FBP treated plots. Solid-state ¹³C NMR spectroscopy further revealed increased aromatic and alkyl groups in BC amended soils which lend to its significantly higher hydrophobicity index, HI (2.13) compared with FBP amended soils (HI = 0.8). Initial biogeochemical responses of amended soils to drought conditions were also investigated during a short-term experiment with drying and rewetting of soils. Increased concentrations of extractable C and higher stimulation of microbial activities (respiration and enzyme activities) in FBP amended soils were measured. Overall, our results reveal different impacts of the two soil amendments, where FBP soil application can affect the labile SOC availability, and stimulate rapid microbial response in drought affected soils, and biochar soil application lowers the labile SOC and microbial stimulation facilitating C sequestration over time.

Direct-acting antiviral treatment for hepatitis C virus infection and risk of incident liver cancer: a retrospective cohort study

BACKGROUND

Eradication of hepatitis C virus (HCV) infection via interferon-based treatment lowers hepatocellular carcinoma risk; some research suggests this effect extends to interferon-free treatment.

AIMS

The objective of this retrospective cohort study was to examine the association of direct-acting antiviral (DAA) exposure with risk of incident liver cancer in real-world data.

METHODS

From United States administrative claims data through March 31, 2017, we identified 30 183 adult HCV patients exposed to DAAs. For comparison, we identified contemporary adult HCV patients without evidence of HCV treatment (N = 137 502), and historical HCV patients treated with interferon prior to the introduction of DAAs (N = 12 948). Included patients had at least 12 months of prior enrolment and no evidence of prior liver cancer at baseline. Hazard ratios (HRs) estimating risk of incident liver cancer associated with DAA treatment were calculated using Cox proportional hazards methods.

RESULTS

Relative to untreated HCV patients, DAA-treated patients were older, more likely to be male, and more likely to have cirrhosis at baseline. After adjustment, DAA treatment was associated with a significantly reduced risk of liver cancer relative to no treatment (adjusted HR = 0.84, 95% CI: 0.73-0.96), and relative to interferon-based treatment in the pre-DAA era (HR = 0.69, 95% CI: 0.59-0.81).

CONCLUSIONS

In this large, population-based study, DAA-based treatment was associated with a reduced risk of incident liver cancer relative to both no HCV treatment and to interferon-based treatment in the pre-DAA era. As additional follow-up time of DAA-treated patients accrues, we anticipate that the long-term benefits of DAA treatment will become more apparent.

Influence of Vegetation on Long-term Phosphorus Sequestration in Subtropical Treatment Wetlands

Sustainable operation of a treatment wetland depends on its continued treatment of influent water to achieve desired outflow water quality targets. Water treatment or nutrient reduction is attained by a combination of biotic and abiotic processes. We studied one of the world's largest treatment wetlands established to revive the Florida Everglades from impacts of excessive phosphorus (P) inputs. Phosphorus retained in the treatment wetlands is sequestered within the accumulated material via biotic and abiotic pathways that are influenced by the existing wetland vegetation. Recently accreted soils (RAS) provide a major sink for stored P, and long-term P removal efficiency of treatment wetlands is governed by the stability of accreted P because more stable P pools are less susceptible to mobilization and loss. We quantified reactive P (extracted with acid and alkali) and nonreactive P (not extracted with acid and alkali) pools in wetland soils by using an operationally defined P fractionation scheme and assessed the effect of emergent vs. submerged vegetation communities on stability of sequestered P. Reactive P comprised 63 to 79% of total P in wetland soils without a clear difference between two vegetation groups. The quantities of reactive P forms (inorganic vs. organic P) were significantly different between two vegetation types. A higher proportion of reactive P was stored as organic P in flocculent detrital organic matter (floc) and RAS under emergent vegetation (46-47% total P) in comparison with submerged vegetation (21-34% total P). The dominant P removal pathway in the submerged vegetation system was associated with calcium whereas plant uptake and peat burial appeared to be the main pathway in the emergent vegetation system.

Safety and efficacy of sofosbuvir-based direct-acting antiviral regimens for hepatitis C virus genotypes 1-4 and 6 in Myanmar: Real-world experience

This open-label, clinical experience investigated the safety and efficacy of direct-acting antiviral (DAA) hepatitis C virus (HCV) therapy in Myanmar; 344 patients completed treatment between June 2015 and May 2016. Patients with HCV genotypes 1-4 and 6 received one of four treatments: (i) Peg-interferon (PEG-IFN)+sofosbuvir (SOF)+ribavirin (RBV) for 12 weeks, (ii) SOF+RBV for 24 weeks, (iii) ledipasvir (LDV)+SOF for 12 weeks or (iv) daclatasvir (DCV)+SOF+RBV for 12 or 24 weeks. Genotype 3 was most common (n=133, 38.7%), followed by genotype 6 (n=122, 35.5%) and genotype 1 (n=86, 25%). Overall, 91% of patients achieved sustained virologic response (SVR); 99% in group 1, (n=148/149), 90% in group 2 (n=95/106), 78% in group 3 (n=65/83) and 100% in group 4 (n=6/6). In group 3, SVR rates were 96.8% in genotype 1 (n=30/31) and 64.1% in genotype 6 (n=25/39). Multivariable regression analysis identified advanced fibrosis (F3-4) (OR=.16 CI: 0.05-0.57, P=.005), genotype 6 (OR=.35, CI: 0.16-0.79, P=.012) and diabetes (OR=.29, CI: 0.12-0.71, P=.007) as negative independent predictors of response. Adverse events were mild with all-oral therapy.

CONCLUSION

DAA therapy ±PEG-IFN achieved high SVR rates. Genotype 6 patients had a low SVR to 12 weeks of LDV and SOF raising the need for other regimens, RBV or longer treatment duration in this population.

Effect of viral suppression on hepatic venous pressure gradient in hepatitis C with cirrhosis and portal hypertension

Portal hypertension is a predictor of liver-related clinical events and mortality in patients with hepatitis C and cirrhosis. The effect of interferon-free hepatitis C treatment on portal pressure is unknown. Fifty patients with Child-Pugh-Turcotte (CPT) A and B cirrhosis and portal hypertension (hepatic venous pressure gradient [HVPG] >6 mm Hg) were randomized to receive 48 weeks of open-label sofosbuvir plus ribavirin at Day 1 or after a 24-week observation period. The primary endpoint was sustained virologic response 12 weeks after therapy (SVR12) in patients who received ≥1 dose of treatment. Secondary endpoints included changes in HVPG, laboratory parameters, and MELD and CPT scores. A subset of patients was followed 48 weeks posttreatment to determine late changes in HVPG. SVR12 occurred in 72% of patients (33/46). In the 37 patients with paired HVPG measurements at baseline and the end of treatment, mean HVPG decreased by -1.0 (SD 3.97) mm Hg. Nine patients (24%) had ≥20% decreases in HVPG during treatment. Among 39 patients with pretreatment HVPG ≥12 mm Hg, 27 (69%) achieved SVR12. Four of the 33 (12%) patients with baseline HVPG ≥12 mm Hg had HVPG <12 mm Hg at the end of treatment. Of nine patients with pretreatment HVPG ≥12 mm Hg who achieved SVR12 and completed 48 weeks of follow-up, eight (89%) had a ≥20% reduction in HVPG, and three reduced their pressure to <12 mm Hg. Patients with chronic HCV and compensated or decompensated cirrhosis who achieve SVR can have clinically meaningful reductions in HVPG at long-term follow-up. (EudraCT 2012-002457-29).

Acute Kidney Injury in Cirrhosis: Baseline Serum Creatinine Predicts Patient Outcomes

OBJECTIVES

The International Ascites Club (IAC) recently defined Stage 1 acute kidney injury (AKI) for cirrhosis as an acute increase in serum creatinine (SCr) by ≥0.3 mg/dl or by ≥50% in <48 h from a stable value within 3 months. The baseline SCr may influence AKI risk and patient outcomes. The objective of this study is to determine in cirrhosis whether the baseline SCr has any effect on the in-hospital AKI course and patient survival.

METHODS

North American Consortium for the Study of End-Stage Liver Disease is a consortium of tertiary-care hepatology centers prospectively enroling non-elective cirrhotic inpatients. Patients with different baseline SCr levels (≤0.5, 0.51-1.0, 1.01-1.5, >1.5 mg/dl) were evaluated for the development of AKI, and compared for AKI outcomes and 30-day survival.

RESULTS

653 hospitalized cirrhotics (56.7±10years, 64% men, 30% with infection) were included. The incidence of AKI was 47% of enrolled patients. Patients with higher baseline SCr were more likely to develop AKI, with significantly higher delta and peak SCr (P<0.001) than the other groups, more likely to have a progressive AKI course (P<0.0001), associated with a significantly reduced 30-day survival (P<0.0001). Multivariate logistic regression showed that the delta SCr during an AKI episode to be the strongest factor impacting AKI outcomes and survival (P<0.001), with a delta SCr of 0.70 mg/dl having a 68% sensitivity and 80% specificity for predicting 30-day mortality.

CONCLUSIONS

Admitted cirrhotic patients with higher baseline SCr are at higher risk for in-hospital development of AKI, and more likely to have AKI progression with reduced survival. Therefore, such patients should be closely monitored and treated promptly for their AKI.

Chronic hepatitis C and chronic kidney disease: Advances, limitations and unchartered territories

Over the past few years, treatment options for chronic hepatitis C virus (HCV) infection have evolved dramatically. The current approved interferon-free direct-acting antiviral (DAA) regimens have been shown to be safe and effective with sustained virologic response (SVR) rates of >90% in most patients. Unique issues yet remain such as the challenges in patients with impaired renal function or decompensated cirrhosis. Patients with stages 4-5 chronic kidney disease (CKD) have a higher prevalence of HCV infection compared with the general population. Chronic HCV in those on dialysis and in kidney transplant recipients is associated with higher morbidity and mortality than uninfected patients. The HCV-infected population is also at risk of developing extrahepatic manifestations associated with altered immune system function and chronic inflammation with cryoglobulinaemic vasculitis being the most common of these manifestations. Therefore, patients with CKD stages 4-5 have to be considered priority patients for HCV therapy. New antiviral therapies have the potential to improve outcomes in this vulnerable patient population, including those on haemodialysis. Recently published studies conducted in kidney transplant recipients have demonstrated successful outcomes. It is thus essential that we carefully select the most appropriate DAA regimen and the best time for treatment in the context of kidney transplantation or cryoglobulinaemic vasculitis. While sofosbuvir, the only approved nucleotide NS5B inhibitor, has been the backbone of most pangenotypic therapeutic regimens, it has a limitation in those with advanced kidney disease. The currently approved regimens for those with stage 4/5 CKD, while effective, have challenges in that they apply to genotype 1/4 and may require RBV for genotype 1a. Globally, genotype 3 is a common infection, and thus, this group with CKD presents a huge unmet need for effective therapies. As therapy of HCV in renal transplant recipients has been highly successful, it provides an opportunity to expand the use of HCV-infected organs in solid organ transplantation.

Evaluation of Ageratum conyzoides in field scale constructed wetlands (CWs) for domestic wastewater treatment

Ageratum conyzoides were evaluated in field scale subsurface flow constructed wetlands (CWs) to quantify its nitrogen (N) and phosphorus (P) uptake and compare with wetland plants (Pistia stratiotes, Typha latifolia and Canna indica). The two-field scale subsurface flow CWs, located in the International Crops Research Institute for Semi-Arid Tropics, received wastewater from an urban colony. The CW1 and CW2 had the same dimensions (length:10 m, width:3 m, total depth:1.5 m and sand and gravel:1 m), similar flow rates (3 m³/d), hydraulic loading rates (HLRs-10 cm/d) and hydraulic retention time (HRT-5 days) from July 2014-August 2015. The vegetation in both CWs consisted of Pistia stratiotes, Typha latifolia, Canna indica, and Ageratum conyzoides, respectively. The CW1 (% reduction with respect to concentrations) reduced total suspended solids (TSS) (68%), NH₄-N (26%), NO₃-N (30%), soluble reactive P (SRP) (20%), chemical oxygen demand (COD) (45%) and fecal coliforms (71%), while the CW2 (%-reduction with respect to concentrations) reduced TSS (63%), NH₄-N (32%), NO₃-N (26%), SRP (35%), COD (39%) and fecal coliforms (70%). Ageratum conyzoides can be used in combination with Pistia stratiotes, Typha latifolia and Canna indica to enhance removal of excessive N, P and fecal coliforms from domestic wastewater.

Ledipasvir-sofosbuvir and sofosbuvir plus ribavirin in patients with chronic hepatitis C and bleeding disorders

INTRODUCTION

Chronic hepatitis C virus (HCV) infection is prevalent among patients with inherited bleeding disorders and is a leading cause of mortality in those with haemophilia.

AIM

We evaluated the efficacy and safety of ledipasvir-sofosbuvir and sofosbuvir plus ribavirin in patients with chronic HCV genotype 1-4 infection and an inherited bleeding disorder.

METHODS

Ledipasvir-sofosbuvir was administered for 12 weeks to patients with genotype 1 or 4 infection and for 12 or 24 weeks to treatment-experienced cirrhotic patients with genotype 1 infection. Patients with genotype 2 and 3 infection received sofosbuvir plus ribavirin for 12 and 24 weeks respectively.

RESULTS

The majority of the 120 treated patients had a severe bleeding disorder (55%); overall, 65% of patients had haemophilia A and 26% of patients had haemophilia B; 22% were HIV coinfected. Sustained virologic response at 12 weeks posttreatment was 99% (98/99) in patients with genotype 1 or 4 infection; 100% (5/5) in treatment-experienced cirrhotic patients with genotype 1 infection; 100% (10/10) in patients with genotype 2 infection; and 83% (5/6) in patients with genotype 3 infection. There were no treatment discontinuations due to adverse events (AEs). The most frequent non-bleeding AEs were fatigue, headache, diarrhoea, nausea and insomnia. Bleeding AEs occurred in 22 patients, of which all but one were considered unrelated to treatment.

CONCLUSION

Treatment with ledipasvir-sofosbuvir for patients with HCV genotype 1 or 4 infection or sofosbuvir plus ribavirin for patients with genotype 2 or 3 infection was highly effective and well tolerated among those with inherited bleeding disorders.

All-oral direct-acting antiviral therapy in HCV-advanced liver disease is effective in real-world practice: observations through HCV-TARGET database

BACKGROUND

Chronic hepatitis C virus therapy in patients with advanced liver disease remains a clinical challenge. HCV-TARGET collects data in patients treated at tertiary academic and community centres.

AIM

To assess efficacy of all-oral HCV therapy in advanced liver disease.

METHODS

Between December 2013 and October 2014, 240 patients with a MELD score of ≥10 initiated HCV treatment with an all-oral regimen. Data from the 220 patients who completed 12-week follow-up were analysed.

RESULTS

Genotype 1 (GT1) patients had higher sustained virological response (SVR) when treated with sofosbuvir plus simeprevir ± ribavirin than with sofosbuvir plus ribavirin (66-74% vs. 54%); GT1b vs GT1a (84% vs. 64%). SVR for GT2 was 72% with sofosbuvir plus ribavirin, while GT3 patients had a substantially lower response (35%). A decrease in MELD score was not clearly related to SVR over the short course of follow-up although some had improvements in MELD score, serum bilirubin and albumin. A predictor of virological response was albumin level while negative predictors were elevated bilirubin level and GT1a. Most patients with GT1 were treated with approximately 12-week duration of sofosbuvir and simeprevir ± ribavirin therapy while GT2 and GT3 patients were treated with approximately 12 and 24 weeks of sofosbuvir plus ribavirin respectively.

CONCLUSIONS

All-oral therapies are effective among patients with advanced liver disease with high levels of success in GT2 and GT1b, and may serve to reduce the severity of liver disease after SVR. Treatment for GT3 patients remains an unmet need. Clinical trial number: NCT01474811.

Interactive effects on CO2, drought, and ultraviolet-B radiation on maize growth and development

Crop growth and development are highly responsive to global climate change components such as elevated carbon dioxide (CO2), drought, and ultraviolet-B (UV-B) radiation. Plant tolerance to these environmental stresses comprises its genetic potential, physiological changes, metabolism, and signaling pathways. An inclusive understanding of morphological, physiological, and biochemical responses to these abiotic stresses is imperative for the development of stress tolerant varieties for future environments. The objectives of this study were to characterize the changes in vegetative and physiological traits in maize hybrids in their response to multiple environmental factors of (CO2) [400 and 750μmolmol(-1) (+(CO2)], irrigation treatments based evapotranspiration (ET) [100 and 50% (-ET)], and UV-B radiation [0 and 10kJm(-2)d(-1) (+UV-B)] and to identify the multiple stress tolerant hybrids aid in mitigating projected climate change for shaping future agriculture. Six maize hybrids (P1498, DKC 65-81, N75H-GTA, P1319, DKC 66-97, and N77P-3111) with known drought tolerance variability were grown in eight sunlit, controlled environment chambers in which control treatment consisted of 400μmolmol(-1) [CO2], 100% ET-based irrigation, and 0kJ UV-B. Plants grown at +UV-B alone or combination with 50% ET produced shorter plants and smaller leaf area while elevated CO2 treatments ameliorated the damaging effects of drought and higher UV-B levels on maize hybrids. Plant height, leaf area, total dry matter chlorophyll, carotenoids, and net photosynthesis measured were increased in response to CO2 enrichment. Total stress response index (TSRI) for each hybrid, developed from the cumulative sum of response indices of vegetative and physiological parameters, varied among the maize hybrids. The hybrids were classified as tolerant (P1498), intermediate (DKC 65-81, N75H-GTA, N77P-3111) and sensitive (P1319 and DKC 66-97) to multiple environmental stresses. The positive correlation between TSRI and vegetative and physiological index developed in this study demonstrates that a combination of vegetative and physiological traits is an effective screening tool to identify germplasm best suited to cope with future changing climates. Furthermore, the tolerant hybrids identified in this study indicate that the possibility of cultivar selection for enhanced agronomic performance and stability in a water limited environment with higher UV-B, anticipated to occur in future climates.

Review article: safety and tolerability of direct-acting anti-viral agents in the new era of hepatitis C therapy

BACKGROUND

Direct-acting anti-virals (DAAs) licensed to treat chronic HCV infection have revolutionised treatment algorithms by drastically mitigating side effects while enhancing efficacy relative to interferon-based therapy.

AIM

To review adverse events (AEs) uniquely associated with DAA therapy across a broad spectrum of patient populations.

METHODS

Searches of PubMed and FDA surveillance studies were undertaken to complete an exhaustive review. Search terms included 'DAAs', 'safety', and 'tolerability'.

RESULTS

While DAAs are remarkably well tolerated, they are accompanied by unique AEs. Simeprevir, an NS3/4A protease inhibitor, has been known, albeit infrequently, to cause mild hyperbilirubinemia and photosensitivity reactions; and paritaprevir boosted with ritonavir causes bilirubin and ALT elevations. Asunaprevir, another protease inhibitor, infrequently causes elevated transaminase levels. NS5A and NS5B inhibitors are well tolerated, although sofosbuvir is contraindicated in patients with severe renal impairment. Ribavirin co-administered in certain treatment regimens has been associated with cough, rash and haemolytic anaemia.

CONCLUSIONS

With the impending reality of a more tolerable interferon-sparing regimen, the future of DAA therapy offers shorter treatment duration, simplified disease management, and a patient-centred regimen. With advantages come drawbacks, including development of resistance to therapy and accessibility to this expensive treatment. DAA therapy continues to advance at a brisk pace with a promising trend for higher tolerability, even in difficult-to-treat subgroups such as those with cirrhosis, nonresponders to prior therapy, and transplant recipients. Subgroup-specific contraindications and safety-related limitations are active areas of research. Concerted research efforts and continuing advances lend hope to the goal of rendering HCV a routinely curable disease.

Comparative Proteomic Analysis of Cotton Fiber Development and Protein Extraction Method Comparison in Late Stage Fibers

The distinct stages of cotton fiber development and maturation serve as a single-celled model for studying the molecular mechanisms of plant cell elongation, cell wall development and cellulose biosynthesis. However, this model system of plant cell development is compromised for proteomic studies due to a lack of an efficient protein extraction method during the later stages of fiber development, because of a recalcitrant cell wall and the presence of abundant phenolic compounds. Here, we compared the quality and quantities of proteins extracted from 25 dpa (days post anthesis) fiber with multiple protein extraction methods and present a comprehensive quantitative proteomic study of fiber development from 10 dpa to 25 dpa. Comparative analysis using a label-free quantification method revealed 287 differentially-expressed proteins in the 10 dpa to 25 dpa fiber developmental period. Proteins involved in cell wall metabolism and regulation, cytoskeleton development and carbohydrate metabolism among other functional categories in four fiber developmental stages were identified. Our studies provide protocols for protein extraction from maturing fiber tissues for mass spectrometry analysis and expand knowledge of the proteomic profile of cotton fiber development.

Effectiveness of Simeprevir Plus Sofosbuvir, With or Without Ribavirin, in Real-World Patients With HCV Genotype 1 Infection

BACKGROUND & AIMS

The interferon-free regimen of simeprevir plus sofosbuvir was recommended by professional guidelines for certain patients with hepatitis C virus (HCV) genotype 1 infection based on the findings of a phase 2 trial. We aimed to evaluate the safety and efficacy of this regimen in clinical practice settings in North America.

METHODS

We collected demographic, clinical, and virologic data, as well as reports of adverse outcomes, from sequential participants in HCV-TARGET--a prospective observational cohort study of patients undergoing HCV treatment in routine clinical care settings. From January through October 2014, there were 836 patients with HCV genotype 1 infection who began 12 weeks of treatment with simeprevir plus sofosbuvir (treatment duration of up to 16 weeks); 169 of these patients received ribavirin. Most patients were male (61%), Caucasian (76%), or black (13%); 59% had cirrhosis. Most patients had failed prior treatment with peginterferon and ribavirin without (46%) or with telaprevir or boceprevir (12%). The primary outcome was sustained virologic response (SVR), defined as the level of HCV RNA below quantification at least 64 days after the end of treatment (beginning of week 12 after treatment--a 2-week window). Logistic regression models with inverse probability weights were constructed to adjust for baseline covariates and potential selection bias.

RESULTS

The overall SVR rate was 84% (675 of 802 patients, 95% confidence interval, 81%-87%). Model-adjusted estimates indicate patients with cirrhosis, prior decompensation, and previous protease inhibitor treatments were less likely to achieve an SVR. The addition of ribavirin had no detectable effects on SVR. The most common adverse events were fatigue, headache, nausea, rash, and insomnia. Serious adverse events and treatment discontinuation occurred in only 5% and 3% of participants, respectively.

CONCLUSIONS

In a large prospective observational cohort study, a 12-week regimen of simeprevir plus sofosbuvir was associated with high rates of SVR and infrequent treatment discontinuation. ClinicalTrials.gov: NCT01474811.

Soil and phosphorus accretion rates in sub-tropical wetlands: Everglades Stormwater Treatment Areas as a case example

Wetlands are known to serve as sinks for particulate matter and associated nutrients and contaminants. Consequently rate of soil accretion is critical for continued performance of wetlands to provide ecosystem services including water quality improvement and reduce excess contaminant loads into downstream waters. Here we demonstrate a new technique to determine rate of soil accretion in selected subtropical treatment wetlands located in southern USA. We also report changes in soil accretion rates and subsequent phosphorus (P) removal efficiency with increasing operational history of these treatment wetlands. Utilizing discernible signatures preserved within the soil depth profiles, 'change points' (CP) that corresponded to specific events in the life history of a wetland were determined. The CP was observed as an abrupt transition in the physico-chemical properties of soil as a manifestation of prevailing historical conditions (e.g. startup of treatment wetlands in this case). Vertical depth of CP from the soil surface was equivalent to the depth of recently accreted soil (RAS) and used for soil accretion rate calculations. Annual soil and P accretion rates determined using CP technique (CPT) in studied wetlands ranged from 1.0±0.3 to 1.7±0.8 cm yr(-1) and 1.3±0.6 to 3.3±2 g m(-2) yr(-1), respectively. There was no difference in RAS depth between emergent and submerged aquatic vegetation communities found at the study location. Our results showed that soil and P accretion rates leveled off after 10 yr of treatment wetlands' operation. On comparison, soil accretion rates and RAS depth determined by CPT were commensurate with that measured by other techniques. CPT can be easily used where a reliable record of wetland establishment date or some significant alteration/perturbation is available. This technique offers a relatively simple alternative to determine vertical accretion rates in free-water surface wetlands.

Evaluation of Legacy Phosphorus Storage and Release from Wetland Soils

To better manage legacy phosphorus (P) in watersheds, reliable techniques to predict P storage and release from uplands, ditches, streams, and wetlands must be developed. Techniques such as the P saturation ratio (PSR) and the soil P storage capacity (SPSC), originally developed for upland soils, are hypothesized to be applicable to wetland soils as well. Surface soils were collected from eight beef ranches within the Lake Okeechobee Watershed, FL, to obtain a threshold PSR value and to evaluate the use of PSR and SPSC for identifying legacy P storage and release from wetland soils. Water-soluble P (WSP) was determined for all soils; the equilibrium P concentration (EPC) was determined for selected soils through the generation of Langmuir isotherms. The threshold PSR for wetland soils, calculated from P, Fe, and Al in a Mehlich 1 solution, was determined to be 0.1; SPSC, calculated using the threshold PSR, was found to be related to WSP. When SPSC was positive, WSP and EPC were minimal. However, both WSP and EPC increased once SPSC became negative. Organic matter (OM) varied from 0.4 to 90 g kg for both positive and negative SPSC, suggesting that OM in wetland soils does not have any effect on P retention and release below the threshold PSR. Moreover, when a wetland or drainage ditch is heavily P impacted, it could be a P source; wetland vegetation may no longer be able to assimilate additional P, resulting in P loss from the soil. This study suggests that the PSR-SPSC concept could be a valuable tool for evaluating legacy P release from wetlands.

Review article: the efficacy and safety of daclatasvir in the treatment of chronic hepatitis C virus infection

BACKGROUND

The treatment of hepatitis C virus (HCV) has evolved dramatically after the introduction of direct acting anti-virals. NS5A protein plays an important role in HCV replication and is an attractive target for drug development.

AIM

To review clinical studies on the efficacy and safety of direct-acting anti-virals regimens containing daclastavir, an NS5A inhibitor, in the treatment of chronic hepatitis C.

METHODS

A Medline search was undertaken to identify relevant literature using search terms including 'daclatasvir', 'HCV treatment' and 'NS5A inhibitors'. Furthermore, we scanned abstracts presented at the recent international meetings in liver disease, viral hepatitis and infectious disease, as well as the reference lists of the review articles to identify publications not retrieved by electronic searches.

RESULTS

Daclatasvir is the first-in-class HCV NS5A inhibitor that has been demonstrated in Phase I-III trials to have a potent anti-viral effect and clinical efficacy across multiple HCV genotypes (GT). Daclastavir is generally safe and well tolerated, with a low barrier to resistance and low potential for drug-drug interaction. When Daclastavir is added to PEG-IFN/RBV platform, sustained virological response (SVR) rates are increased significantly compared with PEG-IFN/RBV alone. The all-oral combination of Daclastavir/asunaprevir (ASV; protease inhibitor) has high SVR rates against GT1b, but less activity against GT1a. Dual combination of Daclastavir/Sofosbuvir (SOF; nucleotide polymerase inhibitor) and triple combination of Daclastavir/ASV/beclabuvir (BCV; non-nucleoside polymerase inhibitor) have demonstrated >90% SVR rates in both treatment naïve and treatment-experienced patients with GT1. Furthermore, Daclastavir/SOF combination has also demonstrated up to 90% SVR rates in patients with GT3, and in those with human immunodeficiency virus coinfection, cirrhosis and post-transplant HCV recurrence with any GT. Daclastavir/ASV/BCV has primarily demonstrated near 100% SVR rates in patients with GT4.

CONCLUSION

Daclastavir-containing regimens, with or without PEG-IFN, have shown promising results in clinical trials, and present an excellent treatment option for those with chronic HCV and for multiple genotypes.

Features and Outcomes of 899 Patients With Drug-Induced Liver Injury: The DILIN Prospective Study

BACKGROUND & AIMS

The Drug-Induced Liver Injury Network is conducting a prospective study of patients with DILI in the United States. We present characteristics and subgroup analyses from the first 1257 patients enrolled in the study.

METHODS

In an observational longitudinal study, we began collecting data on eligible individuals with suspected DILI in 2004, following them for 6 months or longer. Subjects were evaluated systematically for other etiologies, causes, and severity of DILI.

RESULTS

Among 1257 enrolled subjects with suspected DILI, the causality was assessed in 1091 patients, and 899 were considered to have definite, highly likely, or probable DILI. Ten percent of patients died or underwent liver transplantation, and 17% had chronic liver injury. In the 89 patients (10%) with pre-existing liver disease, DILI appeared to be more severe than in those without (difference not statistically significant; P = .09) and mortality was significantly higher (16% vs 5.2%; P < .001). Azithromycin was the implicated agent in a higher proportion of patients with pre-existing liver disease compared with those without liver disease (6.7% vs 1.5%; P = .006). Forty-one cases with latency ≤7 days were caused predominantly by antimicrobial agents (71%). Two most common causes for 60 DILI cases with latency >365 days were nitrofurantoin (25%) or minocycline (17%). There were no differences in outcomes of patients with short vs long latency of DILI. Compared with individuals younger than 65 years, individuals 65 years or older (n = 149) were more likely to have cholestatic injury, although mortality and rate of liver transplantation did not differ. Nine patients (1%) had concomitant severe skin reactions; implicated agents were lamotrigine, azithromycin, carbamazepine, moxifloxacin, cephalexin, diclofenac, and nitrofurantoin. Four of these patients died.

CONCLUSIONS

Mortality from DILI is significantly higher in individuals with pre-existing liver disease or concomitant severe skin reactions compared with patients without. Additional studies are needed to confirm the association between azithromycin and increased DILI in patients with chronic liver disease. Older age and short or long latencies are not associated with DILI mortality.

Discovery of a Cyclic Boronic Acid β-Lactamase Inhibitor (RPX7009) with Utility vs Class A Serine Carbapenemases

The increasing dissemination of carbapenemases in Gram-negative bacteria has threatened the clinical usefulness of the β-lactam class of antimicrobials. A program was initiated to discover a new series of serine β-lactamase inhibitors containing a boronic acid pharmacophore, with the goal of finding a potent inhibitor of serine carbapenemase enzymes that are currently compromising the utility of the carbapenem class of antibacterials. Potential lead structures were screened in silico by modeling into the active sites of key serine β-lactamases. Promising candidate molecules were synthesized and evaluated in biochemical and whole-cell assays. Inhibitors were identified with potent inhibition of serine carbapenemases, particularly the Klebsiella pneumoniae carbapenemase (KPC), with no inhibition of mammalian serine proteases. Studies in vitro and in vivo show that RPX7009 (9f) is a broad-spectrum inhibitor, notably restoring the activity of carbapenems against KPC-producing strains. Combined with a carbapenem, 9f is a promising product for the treatment of multidrug resistant Gram-negative bacteria.

Peginterferon and ribavirin for treatment of recurrent hepatitis C disease in HCV-HIV coinfected liver transplant recipients

Achievement of a sustained virologic response (SVR) with antiviral therapy significantly improves graft survival in hepatitis C virus (HCV) monoinfected liver transplant (LT) patients. Risks and benefits of HCV therapy in HCV-human immunodeficiency virus (HIV) coinfected LT recipients are not well established. Among 89 HCV-HIV LT recipients in the HIVTR cohort, 39 (23% Black, 79% genotype 1, 83% fibrosis stage ≤ 1) were treated with peginterferon-a2a or a2b plus ribavirin for a median 363 days (14-1373). On intent-to-treat basis, 22% (95% CI: 10-39) and 14% (95% CI: 5-30) achieved an end-of-treatment response (EOTR) and SVR, respectively. By per-protocol analysis (completed 48 weeks of therapy ± dose reductions), 42% and 26% had EOTR and SVR, respectively. Severe adverse events occurred in 85%, with 26% hospitalized with infections and 13% developing acute rejection. Early discontinuations and dose reductions occurred in 38% and 82%, respectively, despite use of growth factors in 85%. Eighteen of 39 treated patients (46%) subsequently died/had graft loss, with 10 (26%) attributed to recurrent HCV. In conclusion, SVR rates are low and tolerability is poor in HCV-HIV coinfected transplant recipients treated with peginterferon and ribavirin. These results highlight the critical need for better tolerated and more efficacious HCV therapies for HCV-HIV coinfected transplant recipients.

Review article: HCV genotype 3 – the new treatment challenge

BACKGROUND

Over the past several years, hepatitis C therapy has been pegylated interferon and ribavirin based. Although protease inhibitor-based therapy has enhanced response rates in genotype 1, the recent advances in therapy have demonstrated a challenge in genotype 3, a highly prevalent infection globally.

AIM

To provide a comprehensive summary of the literature evaluating the unique characteristics and evolving therapies in genotype 3.

METHODS

A structured search in PubMed, the Cochrane Library and EMBASE was performed using defined key words, including only full text papers and abstracts in English.

RESULTS

HCV genotype 3 is more prevalent in Asia and among intra-venous drug users. Furthermore, it interferes with lipid and glucose metabolism, and the natural history involves a more rapid progression of liver disease and a higher incidence of hepatocellular carcinoma (HCC). New therapies with protease inhibitors have focused on genotype 1 largely and have demonstrated enhanced responses, but have limited activity against genotype 3. Thus far, in clinical trials, NS5B and NS5A inhibitors have performed more poorly in genotype 3, while a cyclophilin inhibitor, alisporivir, has shown promise.

CONCLUSIONS

As treatments for HCV have evolved, genotype 3 has become the most difficult to treat. Furthermore, genotype 3 has special characteristics, such as insulin resistance and alterations in lipid metabolism, which may partly explain the lower treatment responses. A great deal of emphasis on advancing therapy is needed in this population that appears to have a more rapid progression of liver disease and a higher incidence of HCC.

Donor hemosiderosis does not affect liver function and regeneration in the setting of living donor liver transplantation

Living donor liver transplantation (LDLT) demands a careful assessment of abnormal findings discovered during the evaluation process to determine if there will be any potential risks to the donor or recipient. Varying degrees of elevated hepatic iron levels are not uncommonly seen in otherwise healthy individuals. We questioned whether mild expression of hemosiderin deposition presents a safety concern when considering outcomes of living donation for both the donor and the recipient. We report on three LDLT patients who were found to have low- to moderate-grade hemosiderin deposition on liver biopsy. All other aspects of their evaluation proved satisfactory, and the decision was made to proceed with donation. There were no significant complications in the donors, and all demonstrated complete normalization of liver function postoperatively, with appropriate parenchymal regeneration. The recipients also had unremarkable postoperative recovery. We conclude that these individuals can be considered as potential donors after careful evaluation.