The characterization of the Bacillus thuringiensis (Berliner) LBIT-418 strain was based on a previous work which indicated its high insecticidal potential. Therefore, toxicological, molecular, and ...biochemical characterizations were conducted in this work to identify its unique features and its potential to be developed as a bioinsecticide. This strain, originally isolated from a healthy mosquito larva, was identified within the subspecies kenyae by sequencing of the hag gene and by the multilocus sequence typing (MLST) technique. Genes cry1Ac2, cry1Ea3, cry2Aa1 and cry2Ab4, and a cry1Ia were detected in its genome, in addition to a vip3Aa gene. In this research, the latter protein was successfully cloned, expressed, and purified and showed high toxicity towards the fall armyworm, Spodoptera frugiperda (J.E. Smith), fourth instar larvae in bioassays using the microdroplet ingestion technique, estimating an LD50 of 21.38 ng/larva. Additional bioassays were performed using the diet surface inoculation technique of the strain's spore-crystal complex against diamondback moth larvae, Plutella xylostella (Linnaeus), estimating an LC50 of 10.22 ng/cm2. Its inability to produce β-exotoxin was demonstrated by bioassays against the nematode Caenorhabditis elegans Maupas and by HPLC analysis. These results support the high potential of this strain to be developed as a bioinsecticide. Graphical Abstract
The correct description of crude oil/water interfaces is a very complex and an important task, particularly to the oil industry, whose main difficulty relies on understanding how the interfacial ...properties (i.e., interfacial tension and interfacial accumulation) of the system are affected by a very large number of components. To give some additional insight to the oil/water interfacial behavior, eleven oil/water mixtures (i.e., six binary, four ternary and a quaternary mixture) have been modeled through atomistic molecular dynamics simulations at laboratory conditions. All mixtures were built with a model oil based on dodecane, toluene, quinoline and a naphthenic acid, to represent the saturated, aromatic, basic resin and acid resin fractions, respectively.
The results from this contribution show that interfacial tensions can be correlated to interfacial accumulation, which can be used as good starting point in predicting interfacial properties of oil mixtures. Additionally, the interfacial properties of mixtures behave similarly to the most polar pure oil/water interface, while all other compounds stay in the oil bulk as spectators. This behavior raises the question of whether using common n-alkane oils is a good enough approximation for modeling the interfacial properties of crude oils.
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•Molecular simulation data for many oil/water unexplored mixtures is provided.•Interfacial accumulation of polar oil compounds depends on the matrix oil polarity.•The oil/water interfacial tension can be correlated with interfacial accumulation via MD simulations.•Interfacial properties of oil mixtures can be approximated by a simple Langmuir model.
Fall armyworm (FAW),
Spodoptera frugiperda
(Smith, 1797), is a polyphagous, voracious, and economically important agricultural pest. Biological control of FAW is a strategy that must be further ...explored. This study evaluated six baculovirus strains isolated from infected FAW larvae from Mexico, Argentina, Honduras, and the United States. Five alphabaculoviruses (SfNPV-An
2
, SfNPV-Arg, SfNPV-Fx, SfNPV-Ho, and SfNPV-Sin) and one betabaculovirus (SfGV-RV) were tested against FAW larvae, showing a wide diversity of virulence levels among strains when their estimated LC
50
s were compared, being SfNPV-Arg, SfNPV-Ho and SfNPV-Fx more virulent than SfNPV-An
2
, SfNPV-Sin, and SfGV-RV. To determine any virulence difference in vitro studies of these isolates, Sf9 cell cultures were used. Interestingly, only ODVs from four of the test SfNPV strains showed infectivity on Sf9 cell cultures, and some differences in virulence were observed. Genomic restriction analyses and partial sequences of
lef-8, lef-9
, and
polh/granulin
genes showed little variability among alphabaculoviruses, both, among them and with previously reported sequences. However, sequences from SfGV-RV were closer to previously reported sequences from the SfGV-VG008 strain than the SfGV-Arg and SfGV-VG014 strains. The great difference in the in vivo virulence was not correlated with great similarity among the isolates. The characterization of these six baculovirus isolates offers the basis for exploring their potential as biological control agents against
S. frugiperda
, as well the initial studies on their specific infection mechanisms, evolution, and ecology.
Objective:
Aspiration of endotracheal secretions is a major step in the prevention of ventilator-associated pneumonia (VAP). We compared
conventional and continuous aspiration of subglottic ...secretions (CASS) procedures in ventilated patients after major heart
surgery (MHS).
Materials and methods:
Randomized comparison during a 2-year period.
Results:
A total of 714 patients were randomized (24 patients were excluded from the study; 359 CASS patients; 331 control subjects).
The results for CASS patients and control subjects (per protocol and intention-to-treat analysis) were as follows: VAP incidence,
3.6% vs 5.3% (p = 0.2) and 3.8% vs 5.1%, respectively; incidence density, 17.9 vs 27.6 episodes per 1,000 days of mechanical
ventilation (MV) p = 0.18 and 18.9 vs 28.7 episodes per 1,000 days of MV, respectively; hospital antibiotic use in daily
defined doses (DDDs), 1,213 vs 1,932 (p < 0.001) and 1,392 vs 1,932, respectively (p < 0.001). In patients who had received
mechanical ventilation for > 48 h, the comparisons of CASS patients and control subjects were as follows: VAP incidence, 26.7%
vs 47.5% (p = 0.04), respectively; incidence density, 31.5 vs 51.6 episodes per 1,000 days of MV, respectively (p = 0.03);
median length of ICU stay, 7 vs 16.5 days (p = 0.01), respectively; hospital antibiotic use, 1,206 vs 1,877 DDD (p < 0.001),
respectively; Clostridium difficile -associated diarrhea, 6.7% vs 12.5% (p = 0.3), respectively; and overall mortality rate, 44.4% vs 52.5% (p = 0.3), respectively.
Reintubation increased the risk of VAP (relative risk RR, 6.07; 95% confidence interval CI, 2.20 to 16.60; p < 0.001),
while CASS was the only significant protective factor (RR, 0.40; 95% CI, 0.16 to 0.99; p = 0.04). No complications related
to CASS were observed. The cost of the CASS tube was 9 vs 1.5 ⬠for the conventional tube.
Conclusions:
CASS is a safe procedure that reduces the use of antimicrobial agents in the overall population and the incidence of VAP in
patients who are at risk. CASS use should be encouraged, at least in patients undergoing MHS.
intensive care
major heart surgery
prevention
subglottic aspiration
ventilator-associated pneumonia
The fall armyworm (FAW),
, has been the most devastating pest of corn as well as of other crops in America, and more recently in Africa and Asia. The development of resistance to chemical ...insecticides led the search for environmentally friendly biological alternatives such as baculoviruses. This study focuses on the primary infection of the baculovirus SfNPV-Ar in the FAW's midgut epithelium, by analyzing the differential expression of transcripts in excised midguts at 6, 12, and 24 h post-infection (hpi), and predicted their interactions. Interaction of viral factors with the infected midgut tissue could alters various cellular processes, such as the apoptotic system due to the up-regulation observed of FABP at 6 hpi and of HSP90 at 24 hpi, along with the down-regulated PRX at 6 hpi and FABP transcripts between 12 and 24 hpi. Changes in transcript regulation could affect the cellular architecture of infected cells due to up-regulation of ARP 2/3 at 6 and 12 hpi, followed by down-regulation at 24 hpi. In relation to protein folding proteins, HSP90 was up-regulated at 24 hpi and PDI was down-regulated between 6 and 12 hpi. With respect to metabolism and cellular transport, AcilBP and ATPS0 were up regulated at 6 hpi and 12 hpi, respectively. In reference to transcription and translation up-regulation of RPL11 at 6 hpi and of FPN32 and RPL19 at 24 hpi was detected, as well as the down-regulation of RPL19 at 6 hpi, of PDI and RPL7 at 12 hpi, and of FABP at 24 hpi. In conclusion, gene regulation induced by viral infection could be related to the cytoskeleton and cellular metabolism as well as to oxidative stress, apoptosis, protein folding, translation, and ribosomal structure. The results presented in this work are an approach to understanding how the virus takes control of the general metabolism of the insect host during the primary infection period.
Metropolitan areas in Andean industrialized valleys with a strong geomorphological structure and a pronounced climate experience an increasing degradation of air quality, which motivates ...environmental policies that include the expansion of tree coverage in urban areas among the mitigation measures. Using the metropolitan area of the Aburrá Valley, Colombia, as a study case, we evaluate the removal of PM
2.5
by urban trees with the Urban Forest Effects (UFORE) methodology, considering the potential effect of changing tree covers in the valley for several projected meteorological conditions under climate change and different urban management practices. The estimated removals are sensitive to the number and distribution of available ground stations, with a tendency to overestimate with fewer stations. We found that the marginal gains in removal by additional tree plantings are low in the urbanized settings. In the environmental scenarios, the main limiting factor in the removal is precipitation, compared to changes in tree cover and levels of pollution. Spatially, the increase in total removal depends on the increase in tree cover, with more benefits obtained when trees are in areas with high concentrations of PM
2.5
. Trees with low values of leaf area index (LAI) seem to optimize the effectiveness of the removal. Seasonally, the greatest removal occurs in rainy months when pollution levels are the highest. Based on our results, the scenarios that meet the plans and programs aimed at improving air quality would achieve removal effectiveness of around 2.5% of the total emissions of PM
2.5
with urban trees. Air quality would achieve removal effectiveness of around 2.5% of the total emissions of PM
2.5
with urban trees.
Bacillus thuringiensis
is a potential control agent for plant–parasitic nematodes. Nematode intestinal receptors for Cry21-type toxins are poorly known. Therefore, a strategy was tested as a primary ...screening tool to find possible Cry toxin receptors, using a nematicidal Bt strain and the RNAi technique on
Caenorhabditis elegans
. Six genes encoding intestinal membrane proteins were selected (
abt-4, bre-1, bre-2, bre-3, asps-1, abl-1
) as possible targets for Cry proteins. Fractions of each selected gene were amplified by PCR. Amplicons were cloned into the L4440 vector to transform the
E. coli
HT155 (DE3) strain. Transformed bacteria were used to silence the selected genes using the RNAi feeding method. Nematodes with silenced genes were tested with the Bt strain LBIT-107, which harbors the nematicidal protein Cry21Aa3, among others. Results indicated that nematodes with the silenced
abt-4
gene were 69.5% more resistant to the LBIT-107 strain, in general, and 79% to the Cry21Aa3 toxin, specifically.
The LBIT-1200 strain of Bacillus thuringiensis was recently isolated from soil, and showed a 6.4 and 9.5 increase in toxicity, against Manduca sexta and Trichoplusia ni, respectively, compared to ...HD-73. However, LBIT-1200 was still highly similar to HD-73, including the production of bipyramidal crystals containing only one protein of ∼130 000 kDa, its flagellin gene sequence related to the kurstaki serotype, plasmid and RepPCR patterns similar to HD-73, no production of β-exotoxin and no presence of VIP genes. Sequencing of its cry gene showed the presence of a cry1Ac-type gene with four amino acid differences, including two amino acid replacements in domain III, compared to Cry1Ac1, which may explain its higher toxicity. In conclusion, the LBIT-1200 strain is a variant of the HD-73 strain but shows a much higher toxicity, which makes this new strain an important candidate to be developed as a bioinsecticide, once it passes other tests, throughout its biotechnological development.
A new Bacillus thuringiensis strain 20 times more toxic than the HD-1 strain.
Background. Suspicion of catheter-related bloodstream infection (CR-BSI) leads frequently to unnecessary catheter withdrawals, and many catheter-tip cultures yield negative results. The objective of ...this study was to compare the yield of 3 microbiological procedures to assess CR-BSI without catheter withdrawal. Methods. The study was prospectively performed in a group of patients without neutropenia or blood disorders who were admitted to the intensive care unit during a 37-month period with sepsis suspected on clinical grounds and who had central venous catheters inserted for >48 h. The microbiological procedures compared were semiquantitative cultures from hub and skin (superficial), differential quantitative blood cultures, and differential time to positivity between cultures of blood obtained from catheter hubs and peripheral blood. Results. Of the 204 episodes of suspected CR-BSI included in the study, 28 were confirmed to be CR-BSI. We obtained the following results for sensitivity, specificity, positive and negative predictive values, and accuracy: superficial cultures, 78.6%, 92.0%, 61.1%, 96.4%, and 90.2%, respectively; differential quantitative blood cultures, 71.4%, 97.7%, 83.3%, 95.6%, and 94.1%, respectively; and differential time to positivity, 96.4%, 90.3%, 61.4%, 99.4%, and 91.2%, respectively. Conclusions. CR-BSI can be assessed without catheter withdrawal in patients without neutropenia or blood disorders who have catheters inserted for a short time and are hospitalized in the intensive care unit. Convenience, use of resources, and expertise should determine the technique of choice in different medical contexts. Because of ease of performance, low cost, and wide availability, we recommend combining semiquantitative superficial cultures and peripheral vein blood cultures to screen for CR-BSI, leaving differential quantitative blood cultures as a confirmatory and more specific technique.
Lock-therapy with antimicrobials has been used for the treatment and prevention of catheter-related bloodstream infections (CR-BSI). Experiences with Ethanol-Locks (E-locks) have included therapeutic ...interventions with variable results. Patients undergoing Major Heart Surgery (MHS) are a high-risk population for CR-BSI.The aim of this study was to assess the efficacy and tolerance to E-Locks in the prevention of CR-BSI of patients undergoing MHS.
This is an academic, prospective, randomized, non-blinded and controlled clinical trial assessing the incidence of CR-BSI of patients with E-locks (E-lock) and the tolerance to the procedure in comparison with patients receiving conventional catheter-care (CCC). Patients undergoing MHS with intravascular catheters for more than 48 hours were randomly assigned into treatment or control group by a computer-generated list of randomly assigned numbers. In the treatment group, all their catheter lumens were locked with an ethanol solution at 70% for two hours, every three days (E-Locks). The control group received conventional catheter-care (CCC). Overall, 200 patients with 323 catheters were included in the study, which was stopped after 10 months due to adverse events. Of them, 179 catheters (113 patients) had E-Locks and 144 catheters (87 patients) were CCC. Euroscore Surgical Risk in both groups was 4.04 vs 4.07 p = 0.94 respectively. The results for the E-Locks and CCC were as follows: Incidence of CR-BSI/1000 days of exposure 2.1 vs 5.2 (p = 0.33), catheter tip colonization 14 (7.8%) vs 6 (4.2%) patients (p = 0.17), median length of hospital stay, 15 vs 16 days (p = 0.77). Seven patients (6.19%), all in the ethanol branch, had to discontinue the trial due to intolerance or adverse events.
We do not recommend prophylaxis of CR-BSI with ethanol-lock on a routine basis in patients undergoing Major Heart Surgery.
Clinical Trials.gov NCT01229592.
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