Prolonged Exposure Time Research Articles

Characterization of microparticles derived from waste plastics and their bio-interaction with human lung A549 cells.

Microplastics (MPs) represent a worldwide emerging relevant concern toward human and environmental health due to their intentional or unintentional release. Human exposure to MPs by inhalation is predicted to be among the most hazardous. MPs include both engineered, or primary MPs, and secondary MPs, materials obtained by fragmentation from any plastic good. The major part of the environmental MPs is constituted by the second ones that are irregular in size, shape and composition. These features make the study of the biological impact of heterogenous MPs of extremely high relevance to better estimate the real toxicological hazards of these materials on human and environmental organisms. The smallest fractions of plastic granules, relying on the micron-sized scale, can be considered as the most abundant component of the environmental MPs, and for this reason, they are typically used to perform toxicity tests using in vitro systems representative of an inhalation exposure scenario. In the present work, MPs obtained from industrial treatment of waste plastics (wMPs < 50 μm) were investigated, and after the physico-chemical characterization, the cytotoxic, inflammatory and genotoxic responses, as well as the modality of wMPs interactions with alveolar lung cells, were determined. Obtained results indicated that, at high concentrations (100 μg/ml) and prolonged exposure time (48 h), wMPs affect biological responses by inducing inflammation and genotoxicity, as a result of the cell-wMP interactions, also including the uptake of the smaller particles.

On Escherichia coli Resistance to Fluid Shear Stress and Its Significance for Water Disinfection

Alternative water treatment techniques are needed to overcome the limitations of chemical disinfectants. Stemming from recent findings which point to high levels of shear stress induced by flow as the cause of microbial removal in water, we conducted systematic experiments on bacterial solutions in well-controlled hydrodynamic conditions to evaluate the effect of different levels of shear stress on the viability of Escherichia coli. We investigated a wide range of shear stresses (57–4240 Pa) using viscous substrates prepared by mixing a bacterial solution with thickeners (2-hydroxyethyl cellulose and/or guar gum). Substrate samples were tested for up to 60 min in a laminar shear flow at a constant temperature using a rotational rheometer equipped with a cone-plate measuring system so that the whole sampling volume was exposed to the same shear stress. Results show that, contrary to previous studies, high shear stresses (i.e., of order 103 Pa) do not induce inactivation or lysis of E. coli, even for prolonged exposure times. Stemming from our results and a thorough discussion of the literature on E. coli mechanical lysis and modeling cell dynamics, we infer that E. coli can resist high shear forces because of stress relaxation in a wide range of hydrodynamic conditions.

Uptake and translocation mechanisms of different forms of organic selenium in rice (Oryza sativa L.).

Selenium (Se) is an essential trace element for human and animal health, and toward an understanding of the uptake and translocation of Se in plants is important from the perspective of Se biofortification. In this study, we conducted hydroponic experiments to investigate the mechanisms of organic Se [selenomethionine (SeMet) and selenomethionine-oxide (SeOMet)] uptake, translocation, and the interactions between SeMet and SeOMet in rice. We also investigated differences in the dynamics of organic and inorganic Se uptake by rice roots. Concentration-dependent kinetic results revealed that SeMet uptake during a 1 h exposure was 3.19–16.0 times higher than that of three other Se chemical forms, with uptake capacity (Vmax) values ordered as follows: SeMet>SeOMet>selenite>selenate. Furthermore, time-dependent kinetic analysis revealed that SeMet uptake by roots and content in shoots were initially clearly higher than those of SeOMet, although the differences gradually diminished with prolonged exposure time; while no significant difference was found in the transfer factor of Se from rice roots to shoots between SeMet and SeOMet. Root uptake of SeOMet was significantly inhibited by carbonyl cyanide 3-chlorophenylhydrazone (CCCP) (30.4%), AgNO3 (41.8%), and tetraethylammonium chloride (TEACl) (45.6%), indicating that SeOMet uptake is a metabolically active process, and that it could be mediated via aquaporins and K+ channels. Contrarily, SeMet uptake was insensitive to CCCP, although markedly inhibited by AgNO3 (93.1%), indicating that rice absorbs SeMet primarily via aquaporins. Furthermore, Se uptake and translocation in rice treated simultaneously with both SeMet and SeOMet were considerably lower than those in rice treated with SeMet treatment alone and notably lower than the theoretical quantity, indicating interactions between SeMet and SeOMet. Our findings provide important insights into the mechanisms underlying the uptake and translocation of organic Se within plants.

Effects of Cadmium on Kidney Function of the Freshwater Turtles Mauremys reevesii.

This research studied the effects of cadmium on kidney function of the freshwater turtles Mauremys reevesii. Turtles were injected intraperitoneally with 0, 7.5, 15, and 30mgkg-1 cadmium separately for once. The samples were gathered to check the kidney index, the contents of TP in kidney tissue, and the levels of CRE and BUN in the plasma of the turtles. Results showed that the concentration of TP was overall decreased with the extension of cadmium exposure time and the increasing of the exposure dose of cadmium. The CRE content in the plasma of each treatment group increased with the prolongation of exposure time in a dose-dependent, and the BUN levels of all poisoned groups showed a trend of increasing. The kidney index of treated turtles increased. In summary, cadmium could induce the increase of turtle kidney index, the content of CRE and BUN in plasma, and the decrease of TP content in the kidney.

Comparing the acute and chronic toxicity of flupyradifurone and imidacloprid to non-target aquatic arthropod species

Flupyradifurone (FPF) is a new type of butenolide insecticide. It was launched on the market in 2015 and is considered an alternative to the widely used neonicotinoids, like imidacloprid (IMI), some of which are banned from outdoor use in the European Union. FPF is claimed to be safe for bees, but its safety for aquatic organisms is unknown. Its high water solubility, persistence in the environment, and potential large-scale use make it urgent to evaluate possible impacts on aquatic systems. The current study assessed the acute and chronic toxicity of FPF for aquatic arthropod species and compared these results with those of imidacloprid. Besides, toxicokinetics and toxicokinetic-toxicodynamic models were used to understand the mechanisms of the toxicity of FPF. The present study results showed that organisms take up FPF slower than IMI and eliminate it faster. In addition, the hazardous concentration 5th percentiles (HC05) value of FPF derived from a species sensitivity distribution (SSD) based on acute toxicity was found to be 0.052 µmol/L (corresponding to 15 µg/L), which was 37 times higher than IMI (0.0014 µmol/L, corresponding to 0.36 µg/L). The chronic 28 days EC10 of FPF for Cloeon dipterum and Gammarus pulex were 7.5 µg/L and 2.9 µg/L, respectively. For G. pulex, after 28 days of exposure, the no observed effect concentration (NOEC) of FPF for food consumption was 0.3 µg/L. A toxicokinetic-toxicodynamic (TKTD) model parameterised on the acute toxicity data well predicted the observed chronic effects of FPF on G. pulex, indicating that toxicity mechanisms of FPF did not change with prolonged exposure time, which is not the case for IMI.

Impacts of Metarhizium anisopliae on mortality, energy reserves, and carbohydrase of Trogodermagranarium

Trogoderma granarium Everts is a serious insect pest of the stored products like: wheat, barley, cotton, groundnut, millet, maize, rice, sesame and sorghum. Development of resistance against insecticides is becoming a major issue. So, the current study was planned to assess the bio-pesticidal capacity of Metarhizium anisopliae, which is an entomopathogenic fungus to control this notoriously destructive pest. Toxicity of M. anisopliae was assessed in terms of LC50 by exposing larval T. granarium to five concentrations i.e., 1 × 108, 1 × 107, 1 × 106, 1 × 105 and 1 × 104 conidia/mL suspensions for 7, 14 and 21 days. The increase concentration of conidial suspensions and prolonged exposure time was responsible for higher mortality. The protein concentration and chitinolytic, proteolytic and lipolytic activities of M. anisopliae were found elevated in induced medium containing T. granarium exoskeleton as compared to chitin containing medium. Protease activity level was highest among all of the digestive enzymes, so, in silico analysis was performed to determine whether it could interact with N-acetyl-D-glucosamine the major constitute of exoskeleton. The protease was predicted to bind with N-acetyl-D-glucosamine having a binding energy of 1069.7 kcal/mol and their structure was stabilized by the hydrogen bonds. Moreover, contents of glycogen, total protein, trehalose, total lipids, and soluble protein were significantly decreased 30.211, 6.94, 14.49, 22.02, and 14.8% respectively, while concentration of free amino acid, glucose, DNA and RNA were increased significantly 3.47, 21.65, 6.14 and 28.81% respectively, in infected individuals exposed to LC20 of fungus as compared to controls. For carbohydrase, activities of invertase, catalase and trehalase were increased 10.54, 27.88, and 42.66% while amylase activity was significantly decreased 48.90% in infected individuals exposed to LC20 as compared with control group. The current findings may be used in the production and development of novel myco-pesticide with biodegradable properties and to combat insecticide resistance.

Microcystin-LR exposure enhances toxin-degrading capacity and reduces metabolic diversity of sediment microbial communities

Substantial outbreaks of cyanobacterial harmful algal blooms (cyanoHABs) are accompanied by the prevalent existence of microcystins (MCs) in eutrophic freshwater worldwide, which can compromise the safety of aquatic ecosystems and public health. However, the response of the sediment microbial community to MCs exposure remains unclear. In this study, the sediment microbial communities of Lake Taihu were continuously exposed to environmentally relevant concentration (10 μg/L) of microcystin-LR (MC-LR) in microcosms for three months to mimic MCs contamination during cyanoHABs. Meanwhile, the MC-LR degradation characteristics, metabolic profiles, functional genes, and structures of microbial communities were analyzed periodically. The results showed that the MC-LR degradation capacities of microbial communities significantly increased with prolonged toxin exposure time. The enhanced MC-LR degradation rate was positively correlated with the increase in the abundance of mlr genes, which corresponds to the MC-degrading bacterial community. However, the MC-LR degradation pathway was maintained, and one new biodegradation intermediate (Adda-Glu) was first identified. Moreover, the metabolic profiles of the microbial communities indicated that overall carbon metabolic activity displayed a stimulation-suppression trend, and the exposure led to different carbon utilization patterns. Furthermore, microbial community structure analysis showed that long-term MC-LR exposure enriched microbes associated with MC degradation (Pseudomonas, Stenotrophomonas, Sphingopyxis and Sphingomonas) but inhibited MC-sensitive bacterial genera. This study clearly elucidates that MC-LR exposure alters the function, metabolism, and structure of the sediment microbial community to adapt to polluted environments.

Synthesis, characterization, and evaluation of the photocatalytic properties of zinc oxide co-doped with lanthanides elements

Zinc oxide nanoparticles (NPs) co-doped with various concentrations of lanthanides cerium and ytterbium (Zn1-2xCexYbxO, x = 0.0, 0.01, 0.03, and 0.05) were synthesized via the sol-gel auto-combustion method. All prepared samples including CYZO0 (x = 0.0), CYZO1 (x = 0.01) CYZO3 (x = 0.03), and CYZO5 (x = 0.05) were subsequently characterized. The effects of the concentration of Ce and Yb on the structural, optical, and photocatalytic properties of ZnO NPs were deeply explored. The structural analysis showed that the as-synthesized samples were matched with a hexagonal structure. The co-doping altered the crystal structure of the material. The lattice constants increased with increasing the concentration of Ce and Yb ions. The crystallite size was reduced from 53.24 ± 0.05 nm CYZO0 to 52.28 ± 0.05 nm, 34.90 ± 0.05 nm, and 36.85 ± 0.05 nm for CYZO1, CYZO3, CYZO5, respectively. UV–Vis analysis showed a variation in the bandgap energy values with Yb and Ce co-doping. The photocatalytic activities of Yb and Ce co-doped ZnO were assessed by taking methyl orange (MO) as an organic dye. The absorption peaks at 464 nm for MO dye reduced progressively with prolonged exposure time indicating the presence of the photocatalytic degradation reaction of MO. The constant rate k was found to be 0.027 min−1 for CYZO0, and 0.024 min−1 for CYZO1, and then sharply decreased to 0.0064 min−1, and 0.0065 min−1 for CYZO3 and CYZO5, respectively. It is suggested that the photocatalytic efficiency is intensely dependent on the synergistic effect of both Yb and Ce co-doping.

Influence of Irradiance and Exposure Times on the Mechanical and Adhesive Properties of Universal Adhesives with Dentin

This study evaluated the influence of irradiance/exposure time on the Knoop hardness (KHN) and polymer cross-linking density (PCLD), as well as microtensile bond strength (μTBS), nanoleakage (NL), and in situ degree of conversion (DC) of universal adhesives. Two universal adhesive systems, Clearfil Universal Bond Quick (CUQ) and Scotchbond Universal Adhesive (SBU), were light-cured using various irradiance/exposure times: 1400 mW/cm2 for 5 s (1400*5); 1400 mW/cm2 for 10 s (1400*10); 3200 mW/cm2 for 5 s (3200*5); and 3200 mW/cm2 for 10 s (3200*10). Adhesive disks from each group were used to measure PCLD by KHN. One hundred and twenty-eight human molars were randomly assigned to 16 groups according to the following variables: adhesive system vs adhesive strategies vs radiance/exposure times. After restoration, specimens were sectioned into resin-dentin sticks and tested for μTBS, NL, and DC. The data from PCLD (%), KHN, μTBS (MPa), NL (%), and DC (%) data were subjected to ANOVA and Tukey's test (α=0.05). Significant reductions in KHN, μTBS, and DC (p=0.00001) values and an increase in NL and PCLD (p=0.00001) values were observed for 3200*10 when compared with other groups. Higher KHN, μTBS, and DC (p=0.000001) values were observed for 3200*5 in comparison with the other groups. The 1400*5 (7 J/cm2) and 1400*10 (14 J/cm2) groups showed intermediate values (p=0.000001). Although similar results in terms of hardness, polymer cross-linking density and nanoleakage were observed when 5 seconds at 3200 mW/cm2 and 10 seconds at 1400 mW/cm2 groups were compared, the use of higher irradiance (3200 mW/cm2) for only 5 seconds showed better results in terms of bond strength and degree of conversion for both universal adhesives to dentin. The prolonged exposure time (10 seconds) at the higher irradiance (3200 mW/cm2) showed the worst results.

Выраженность когнитивных и неврологических нарушений у крыс после ишемического инсульта на фоне применения ксенона 0,5 МАК

The majority of stroke patients have cognitive symptoms and about 50% of them live with neurological deficits that critically limit social adaptation capacities even in the absence of significant motor impairments. The aim of this study was to select the optimal length of 0.5 MAC xenon exposure in order to alleviate the neurological and cognitive impairments in experimental stroke. The focal ischemia-reperfusion injury was modeled in rats (n = 70) ising Longa method. The intervention was immediately followed by inhalation of 0.5 MAC xenon for 30, 60 or 120 min. The neurological deficit was assessed using a 'Limb placement' seven-test battery and the cognitive functionalities were assessed by the Morris water maze test. A 30 min 0.5 MAC xenon exposure provided a 40% increase in the limb placement scores and a 17.6% decrease in the Morris water maze test latency compared with the control group (р = 0.055 and р = 0.08, respectively). With a longer 60 min exposure, the trends became significant, the scores improving 2-fold and by 44.4% compared with the control group (р = 0.01 and р = 0.04, respectively), whereas 120 min exposures afforded 2-fold improvements in both tests (р = 0.01). We conclude that, although 30 min post-stroke inhalations provide negligible benefits in terms of neurological status and learning capacity, prolonged exposure times of 60–120 min afford significant improvement in neurological and cognitive indicators and largely alleviate the deteriorating ischemic damage.

Contactless Electrocatheter Tracing within Human Body via Magnetic Sensing: A Feasibility Study.

During surgical procedures, real-time estimation of the current position of a metal lead within the patient’s body is obtained by radiographic imaging. The inherent opacity of metal objects allows their visualization using X-ray fluoroscopic devices. Although fluoroscopy uses reduced radiation intensities, the overall X-ray dose delivered during prolonged exposure times poses risks to the safety of patients and physicians. This study proposes a potential alternative to real-time visualization of a lead inside the human body. In principle, by making a weak current flow through the lead and measuring the related magnetic field generated outside the body, it is possible to trace the position of the lead. This hypothesis was verified experimentally via two tests: one carried out on a curved copper wire in air and one carried out on a real pacemaker lead in a saline solution. In the second test, a pacemaker lead and a large return electrode were placed in a tank filled with a saline solution that reproduced the mean resistivity of the human torso. In both tests, a current flowed through the lead, which consisted of square pulses with short duration, to avoid any neuro-muscular stimulation effects in a real scenario. A small coil with a ferrite core was moved along a grid of points over a plastic sheet and placed just above the lead to sample the spatial amplitude distribution of the magnetic induction field produced by the lead. For each measurement point, the main coil axis was oriented along the x and y axes of the plane to estimate the related components of the magnetic induction field. The two matrices of measurements along the x and y axes were further processed to obtain an estimate of lead positioning. The preliminary results of this study support the scientific hypothesis since the positions of the leads were accurately estimated. This encourages to deepen the investigation and overcome some limitations of this feasibility study.

Exposure to nanoplastic induces cell damage and nitrogen inhibition of activated sludge: Evidence from bacterial individuals and groups

Wastewater treatment plants (WWTPs) are almost the only place where plastic fragments are artificially removed, resulting in mass accumulation of nanoplastics (NPs). In this research, four different concentrations (0 mg/L, 0.1 mg/L, 1 mg/L, 10 mg/L) of polystyrene nanoplastics (PS-NPs) were used to investigate the cell damage and nitrogen inhibition of activated sludge, exposed in a self-assembled SBR reactor for 30 days. Intracellular reactive oxides (ROS) and extracellular lactate dehydrogenase (LDH) increased with the rise of exposure concentration, and morphological analysis disclosed the creases, collapse, and even rupture of cell membranes. However, exposure damage (PS-NPs ≤ 1 mg/L) appeared to be reversible, attributed to that extracellular polymeric substances (EPS) secretion can thicken the three protective layers outside the membrane. PS-NPs did not disrupt the EPS chemical structure, but increased humic acid content. Prolonged exposure time (from 15 to 30 days) was directly related to the nitrogen inhibition. Due to the habitat changes under PS-NPs exposure, abundance and diversity of microorganisms in the original activated sludge decreased significantly, and the dominant phylum was occupied by Patescibacteria (PS-NPs = 10 mg/L). Changes in enzyme activities of AMO, NR, NIR, and NOR with exposure concentration may explain the conversion of nitrogen in SBR. This research broadens our horizons to understand the response mechanism of activated sludge bacteria to PS-NPs exposure individually and collectively.

Acute Nitrite Exposure Induces Dysfunction and Oxidative Damage in Grass Carp Isolated Hemocytes.

To evaluate the effects of nitrite on the oxidative damage of blood cells of Grass Carp Ctenopharyngodon idella, the isolated hemocytes were exposed to nitrite (0, 1, 10, or 100 mg/L) for up to 24 h. Hemoglobin (Hb) and methemoglobin (MetHb) concentrations, reactive oxygen species (ROS) and malondialdehyde (MDA) levels, mitochondrial membrane potential (∆Ψm), and antioxidant enzyme activity were assayed to assess hematological parameters and the antioxidant defense mechanism. Results showed a remarkable decrease in Hb concentration with increasing nitrite concentration after a 24-h exposure, while the MetHb concentration increased significantly in nitrite exposure groups. The levels of ROS, ∆Ψm, and MDA increased to varying degrees with increases in nitrite exposure concentration and time. The total antioxidant capacity, catalase (CAT) activity, glutathione peroxidase (GPx) activity, and glutathione content showed a trend of rising initially and then decreasing with prolonged exposure time. Superoxide dismutase (SOD) activity was higher in the 1-mg/L nitrite exposure group and lower in the 100-mg/L group than in the control. The relative messenger RNA expression ratios of cat, sod1, and gpx were up-regulated significantly in the 1- and 10-mg/L groups and then declined in the 100-mg/L group. Therefore, it can be concluded that nitrite exposure activates the antioxidant defense mechanism of Grass Carp hemocytes and that the balance of oxidant-antioxidant homeostasis will be undermined by higher nitrite doses or longer exposure periods.

Vermiculite as a potential functional additive for water treatment bioreactors inhibiting toxic action of heavy metal cations upsetting the microbial balance

A new adsorbent that combines mineral vermiculite with the yeast Saccharomyces cerevisiae, was used for Cd2+ removal. The influence of vermiculite presence on the toxic effects of Cd2+ to Saccharomyces cerevisiae yeast was evaluated as a function of the microorganisms' respiratory activity (CO2 production). The Cd2+ toxicity increased with prolonged exposure time reaching the LC50 value of 857 and 489 mg L−1 after 30 and 120 min, respectively. The yeast managed to bioaccumulate 25.0 ± 0.6 mg g−1 of Cd2+ at the initial Cd2+ concentration of 741.9 mg L−1; the maximum Cd2+ adsorption capacity of vermiculite reached 25 ± 5 mg g−1. The addition of the mineral decreased the cations toxic effect; the LC20 value in vermiculite absence attained approximately 200 mg L−1 after 30 min and decreased to 80 mg L−1 after 2 h, while in the bio-mineral system it was at the level of 435 ± 50 mg L−1 without a significant change in time. The mineral provided a superior living environment for the yeast by removing part of the cations, releasing essential microelements and providing a protective, clay hutch-like habitat for the cells.

Ozone Efficiency on Two Coleopteran Insect Pests and Its Effect on Quality and Germination of Barley.

Simple SummaryRhyzopertha dominica (Fabricius) and Tribolium castaneum (Herbst) are notorious global pests, destroying various stored grains, including barley, wheat, oats, maize, and rice. Ozone (O3) is a promising fumigant to control pests in stored grain since it can safely and rapidly auto-decompose without leaving residues, however, relatively few studies have focused on the toxicity of O3 on stored grain pests in stored barley. In this study we not only explored the susceptibility of all life stages of R. dominica and T. castaneum in barley seeds to different durations of gaseous O3, but also investigated the effect of O3 on germination ability, seedling growth, and quality of barley. O3 was effective against all life stages of two species in barley under sufficient exposure times without negative impacts affecting the commercial quality of barley. However, the germination ability and seedling growth were adversely impacted at longer O3 exposure times. Thus, it is imperative to select an optimal O3 exposure time to achieve the desired functional outcome, such as malting, animal feeding, and human consumption.Ozone (O3) is a potential fumigant to control pests in stored grain since it can safely and rapidly auto-decompose without leaving residues. In this study, the efficacy of O3 on all life stages of Rhyzopertha dominica (Fabricius) and Tribolium castaneum (Herbst) in barley and the physiological effects on barley and its quality were investigated. Complete control of all life stages of pests was obtained at 700 ppm for 1440 min of ozone exposure without negatively impacting the contents of soluble protein, moisture content, seed colour, hardness, and the weight of thousand barley seeds. The eggs and pupae of these two insects were the more tolerant stages than their larvae and adults. Prolonged exposure times (40 to 1440 min) and mortality assessment intervals (1, 2, and 7 days) increased O3 efficacy due to the reaction characteristics and delayed toxicity. Aging barley seeds appeared to be more sensitive to prolonged ozone duration than new seeds. A total of 20 and 40 min could promote germination rate, and longer O3 exposure (1440 min) was unfavourable for germination and seedling growth. Thus, it is imperative to select an optimal O3 exposure time to transfer ozone into quality contributors of final products and achieve the desired functional outcomes.

Enzyme-mediated intratumoral self-assembly of nanotheranostics for enhanced imaging and tumor therapy.

Enzyme-mediated intratumoral self-assembled (EMISA) nanotheranostics represent a new class of smart agents for combined imaging and therapy of cancer. Cancer cells overexpress various enzymes that are essential for high metabolism, fast proliferation, and tissue invasion and metastasis. By conjugating small molecules that contain an enzyme-specific cleavage site to appropriate chemical linkers, it is possible to induce self-assembly of nanostructures in tumor cells having the target enzyme. This approach of injecting small theranostic molecules that eventually become larger nanotheranostics in situ avoids some of the major limitations that are encountered when injecting larger, pre-assembled nanotheranostics. The advantage of EMISA nanotheranostics include the avoidance of nonspecific uptake and rapid clearance by phagocytic cells, increased cellular accumulation, reduced drug efflux and prolonged cellular exposure time, all of which lead to an amplified imaging signal and therapeutic efficacy. We review here the different approaches that can be used for preparing EMISA-based organic, inorganic, or organic/inorganic hybrid nanotheranostics based on noncovalent interactions and/or covalent bonding. Imaging examples are shown for fluorescence imaging, nuclear imaging, photoacoustic imaging, Raman imaging, computed tomography imaging, bioluminescent imaging, and magnetic resonance imaging. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Biology-Inspired Nanomaterials > Peptide-Based Structures.

Short-term exposure to silver nano-particles alters the physiology and induces stress-related gene expression in Nelumbo nucifera

Lotus (Nelumbo nucifera) was used as model plant in this study to explore its physiology and molecular response upon short-term exposure to silver nano-particles (AgNPs). Accumulation patterns demonstrated a potential uptake of AgNPs by roots and transport to the leaves as a likely key translocation route in lotus. AgNPs exposure was negatively correlated with lotus growth, including germination rate and petiole length in a concentration-dependent manner. Synthesis of chloroplast pigments in lotus leaves was enhanced by low AgNPs concentration, but were inhibited at high concentration. Hydrogen peroxide (H2O2) was detected in lotus leaves after AgNPs treatment. Proline accumulation in lotus leaves was induced with the increase in AgNPs concentration and exposure time. Antioxidant enzyme activities of superoxide dismutase (SOD), peroxidase (POD) as well as catalase (CAT) were enhanced after the first day of AgNPs exposure, but declined with increased exposure time, indicating a time-dependent toxicity of AgNPs. In addition, real-time PCR revealed that two detoxification-related genes, GSH1 and GST, could be activated on the first day of AgNPs exposure, but down-regulated with prolonged AgNPs treatment. Photosynthesis-related RbcS gene was up-regulated, however, no obvious difference in the expression of RbcL was observed after the first day of AgNPs exposure. Moreover, WRKY70a and WRKY70b transcription factors exhibited similar expression patterns, with the highest induction after a 5 mg/L AgNPs exposure on the first day, which decreased with prolonged exposure time. This study provides useful references for further evaluation of the toxic mechanism of AgNPs and their bio-effects on aquatic plants and ecosystems.

Meticillin-resistant Staphylococcus aureus Contact Screening Strategy in a Low Prevalence Setting; a Nested Case-Control Study

SummaryBackgroundThe optimal screening strategy in hospitals to identify secondary cases after contact with a meticillin-resistant Staphylococcus aureus (MRSA) index patient in a low prevalence setting is not well defined. We aimed at identifying factors associated with documented MRSA transmissions.MethodSingle center, retrospective, nested case-control study. We evaluated the screening strategy in our 950 bed tertiary care hospital from 2008 – 2014. Room and ward contacts of MRSA index patients present at time of MRSA identification were screened. We compared characteristics of Staphylococcus aureus Protein A (spa)-type matched contact patients (cases) to negative or spa-type mismatched contact patients (controls).ResultsAmong 270,000 inpatients from 2008 – 2014, 215 MRSA screenings yielded 3013 contact patients, and 6 (0.2%) spa-type matched pairs. We included 225 controls for the nested case-control study. The contact type for the cases was more frequently “same room” and less frequently “same ward” compared with the controls (P = 0.001). Also, exposure time was longer for cases (median of 6 days [IQR 3–9]) than for controls (1 day [0–3], P=0.016).ConclusionThe extensive MRSA screening strategy revealed only few index/contact matches based on spa-typing. Prolonged exposure time and a shared room were significantly associated with MRSA transmission. A targeted screening strategy may be more useful in a low prevalence setting than screening entire wards.

Aptness of entomogenus fungi with diatomaceous earth against various stored grain insect pests

BackgroundNumerous biotic and abiotic factors are responsible for losses of grains quality and quantity during storage. Insecticides used to control stored grain insect pests are not only hazardous to mammals and environment but also induce resistance in insect pests towards these synthetic chemicals. A current trial was conducted, during 2020, in a stored grain laboratory at the College of Agriculture, BZU, Bahadur Sub Campus, Layyah, Punjab, Pakistan. A diatomaceous earth (DE) formulation enhanced with bitterbarkomycin (DEBBM) and combined with Beauveria bassiana (Balsamo) Vuillemin was evaluated against Cryptolestes ferrugineus, (Stephens) (Coleoptera: Laemophloeidae), Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) and Tribolium castaneum (Coleoptera: Tenebrionidae) under laboratory conditions.ResultsDEBBM was applied at the rate of 50 mg/kg, DE (150 mg/kg) and Beauveria bassiana (1.5 × 108 and 1.5 × 1010 conidia/kg) alone as well as in combination with wheat, rice and maize. Treated adult mortality was recorded at 7, 14 and 21 days after exposure. Results of the current study showed that insect pest mortality was maximum in the case of combined application of DEBBM with B. bassiana (high concentration) at prolonged exposure time as compared to their alone application. Mortality of C. ferrugineus was maximum in wheat and rice (100%) over maize (97%), while, R. dominica exhibited high mortality in wheat (100%) followed by rice (97%) and maize (94%) at combined application of DEBBM with B. bassiana (high concentration) after 21 days. Regarding T. castaneum mortality was high in wheat (100%) followed by rice (93%) and maize (88%) in case of combined application of DEBBM with B. bassiana (high concentration) at prolonged exposure time (21 days).ConclusionIn crux, the current trial showed that a mixture of DEBBM and B. bassiana is helpful in controlling tested insect pests.

Analysis of time exposure to DNA touch quality on face shield using STR CODIS – TH01 and D18S51

A number of countries, including Indonesia, have taken preventive measures and made efforts to break the chain of the spread of COVID-19. The impact of government policies is felt in the economic sector, which causes many people to lose their jobs but is required to meet the needs of daily life. This affects the increase in crime rates during the pandemic, which coincides with the government's policy to implement health protocols by using face shields outside the home. This allows the discovery of evidence in the form of a face shield to be identified through DNA touch. This type of research is experimental analytic with a time-series design. This study aims to analyze the effect of exposure to the environmental temperature range of 28.2 oC - 29.3 oC and humidity range of 88 - 94.2% on the quality of DNA touch on the face shield by giving the 1st, 7th, and 14th-day duration treatment using STR CODIS. TH01 and D18S5. The result is an effect of prolonged exposure time on DNA quality, as evidenced by the Anova test with p &lt; 0.05.