is an important opportunistic pathogen that commonly causes nosocomial infections and contributes to substantial morbidity and mortality. We sought to investigate the antibiotic resistance profile, ...pathogenic potential and the clonal relationships between
(
= 25) isolated from patients and sources at a tertiary care hospital's intensive care units (ICUs) in the northern region of Brazil. Most of
isolates (
= 21, 84%) were classified as multidrug resistant (MDR) with high-level resistance to β-lactams, aminoglycosides, quinolones, tigecycline, and colistin. All the 25 isolates presented extended-spectrum beta-lactamase-producing (ESBL), including carbapenemase producers, and carried the
(100%),
(100%),
variants (
= 24, 96%),
group (
= 21, 84%) and
group (
= 18, 72%) genes. The K2 serotype was found in 4% (
= 1) of the isolates, and the K1 was not detected. The virulence-associated genes found among the 25 isolates were
D (
= 24, 96%),
H-1 (
= 22, 88%),
B (100%),
A (
= 10, 40%),
S (
= 15, 60%). The genes related with efflux pumps and outer membrane porins found were
(100%),
C (
= 24, 96%),
K (
= 22, 88%),
K35 (
= 15, 60%), and
K36 (
= 7, 28%). ERIC-PCR was employed to determine the clonal relationship between the different isolated strains. The obtained ERIC-PCR patterns revealed that the similarity between isolates was above 70%. To determine the sequence types (STs) a multilocus sequence typing (MLST) assay was used. The results indicated the presence of high-risk international clones among the isolates. In our study, the wide variety of MDR
harboring β-lactams and virulence genes strongly suggest a necessity for the implementation of effective strategies to prevent and control the spread of antibiotic resistant infections.
Alkane Functionalization Pombeiro, Armando J. L; Guedes da Silva, Maria de Fatima Costa
2019, 2018-12-19, 2018-12-28
eBook
Written by a team of leading experts on the topic, the book examines the latest research developments in the synthesis of valuable functionalized organic compounds from alkanes. The authors describe ...the various modes of interaction of alkanes with metal centres and examine theoxidative alkane functionalization upon C-O bond formation. They address the many types of mechanisms, discuss typical catalytic systems and highlight the strategies inspired by biological catalytic systems.
In this work, we present a computational investigation on the structure and energetics of eleocarpanthraquinone, a newly isolated polyphenolic anthrone-antraquinone. Properties such as bond lengths, ...angles, atomic charges, bond dissociation enthalpies (BDEs), and ionization potential (IP) were determined through the use of density functional theory (DFT). The B3LYP and M06-2X exchange-correlation functionals were employed along with the 6-31+G(d,p), 6-31+ +G(d,p), and 6-311+G(d,p) basis sets for performing computations in the gas-phase, water, methanol, and ethanol. The conformation presenting all the hydroxyl groups undergoing hydrogen-bond interactions with neighboring oxygen atoms (conformation 5) was assigned as the most stable structure while its counterpart presenting no hydrogen-bond interaction was found to be 36.45 kcal/mol less stable than conformation 5 in the potential energy surface probed at the B3LYP/6-311+G(d,p) level of theory in the gas-phase, for instance. More importantly, the lowest O–H bond dissociation enthalpy was determined to be 93.80 kcal/mol at the B3LYP/6-311+G(d,p) level of theory in water against the 146.58 kcal/mol regarding the IP computed at the same approach, suggesting the hydrogen atom transfer mechanism as being preferred over the single electron transfer mechanism in regards to the antioxidant potential for the case of eleocarpanthraquinone; the same conclusion was drawn from the outcomes of all the other approaches used.
Water generated during oil exploration is chemically complex and contains high concentrations of ammonium and, in some cases, high salinity. The most common way to remove ammonium from effluent is a ...biological process, which can be performed by different routes and different groups of microorganisms. However, the presence of salts in the effluents could be an inhibiting factor for biological processes, interfering directly with treatment. This study aimed to evaluate changes in the profile of a microbial community involved in the process of ammonium removal when subjected to a gradual increase of salt (NaCl), in which the complete inhibition of the ammonium removal process occurred at 125 g L
−1
NaCl. During the sludge acclimatization process, samples were collected and submitted to denaturing gradient gel electrophoresis (DGGE) and massive sequencing of the 16S ribosomal RNA (rRNA) genes. As the salt concentration increased in the reactor, a change in the microbial community was observed by the DGGE band profiles. As a result, there was a reduction in the presence of bacterial populations, and an increase in archaeal populations was found. The sequencing data suggested that ammonium removal in the reactor was carried out by different metabolic routes by autotrophic nitrifying bacteria, such as
Nitrosococcus
,
Nitrosomonas
,
Nitrosovibrio
,
Nitrospira
, and
Nitrococcus
; ammonium-oxidizing archaea
Candidatus nitrosoarchaeum
; ANAMMOX microorganisms, such as
Candidatus brocadia, Candidatus kuenenia
, and
Candidatus scalindua
; and microorganisms with the potential to be heterotrophic nitrifying, such as
Paracoccus
spp.,
Pseudomonas
spp.,
Bacillus
spp.,
Marinobacter
sp., and
Alcaligenes
spp.
Most of the synthetic polymers that are used for packaging industry come from fossil fuel; thus, when their life cycle is complete, they normally accumulate in the environment. The ...poly(3-hydroxybutyrate) is a biopolymer produced from bacteria; due to its microbial degradation, great attention has been paid to its research; nevertheless, it has been found to be necessary to improve its mechanical, thermal and barrier properties. One of the approaches to do so is the incorporation of inorganic compounds. Zirconium oxide (ZrO
2
) and zirconium hydroxide (Zr(OH)
4
) have outstanding thermal stability and are potential compounds for the improvement in PHB features. Along this study, hybrid films made of PHB with 0.01, 0.05 and 0.1 mass% of ZrO
2
and Zr(OH)
4
were produced; their properties were evaluated by TG and DSC, which permitted to observe that all the composites have improved thermal resistance; furthermore, 0.01 and 0.05% Zr(OH)
4
showed lower
Wc
. These results suggest that zirconium-based PHB composites can increase the process temperature range, which opens the new door to future applications on food packaging.
The extracts of medicinal plants are used for the treatment of seeds in order to reduce the action of phytopathogens and increase the vigor of the seeds. Currently, computerized image analysis has ...been used to assess the physiological quality of seed lots. The objective was to evaluate the efficiency of the Vigor-S® software in the evaluation of the physiological quality of cowpea seeds treated with essential oils, comparing with a traditional test and the principal component analysis. Two cowpea cultivars were analyzed, BRS Tumucumaque and BRS Guariba, treated with doses of natural extracts of Alfavaca, garlic, horsetail, citronella and pyroligneous acid. The traditional method consisted of evaluations for germination, first germination count, seedling emergence, emergence speed index, accelerated aging, fresh matter and dry matter of seedling and the image analysis for: seedling length, growth index, uniformity index, vigor index, and germination. A Principal component analysis was applied to reduce the number of variables. Horsetail, Alfavaca and citronella extracts were efficient in increasing the physiological quality of the seeds of at least one cultivar. The Vigor-S® software proved to be efficient compared to traditional tests to assess the physiological quality of seeds. Principal Component Analysis is an ally to identify the best extracts and doses to be used. The image analysis method proved to be effective when compared to the traditional method and can therefore be used.
Photodynamic therapy is a promising approach for cancer treatment that relies on the administration of a photosensitizer followed by tumor illumination. The generated oxidative stress may activate ...multiple mechanisms of cell death which are counteracted by cells through adaptive stress responses that target homeostasis rescue. The present renaissance of PDT was leveraged by the acknowledgment that this therapy has an immediate impact locally, in the illumination volume, but that subsequently it may also elicit immune responses with systemic impact. The investigation of the mechanisms of cell death under the oxidative stress of PDT is of paramount importance to understand how the immune system is activated and, ultimately, to make PDT a more appealing/relevant therapeutic option.
Preclinical evidence depicts the capacity of redaporfin (Redp) to act as potent photosensitizer, causing direct antineoplastic effects as well as indirect immune‐dependent destruction of malignant ...lesions. Here, we investigated the mechanisms through which photodynamic therapy (PDT) with redaporfin kills cancer cells. Subcellular localization and fractionation studies based on the physicochemical properties of redaporfin revealed its selective tropism for the endoplasmic reticulum (ER) and the Golgi apparatus (GA). When activated, redaporfin caused rapid reactive oxygen species‐dependent perturbation of ER/GA compartments, coupled to ER stress and an inhibition of the GA‐dependent secretory pathway. This led to a general inhibition of protein secretion by PDT‐treated cancer cells. The ER/GA play a role upstream of mitochondria in the lethal signaling pathway triggered by redaporfin‐based PDT. Pharmacological perturbation of GA function or homeostasis reduces mitochondrial permeabilization. In contrast, removal of the pro‐apoptotic multidomain proteins BAX and BAK or pretreatment with protease inhibitors reduced cell killing, yet left the GA perturbation unaffected. Altogether, these results point to the capacity of redaporfin to kill tumor cells via destroying ER/GA function.
Synopsis
Redaporfin, a latest generation light‐sensitizing agent employed in photodynamic anti‐tumor therapy, acts via selective damage of endoplasmic reticulum (ER) and Golgi apparatus (GA), leading to reactive oxygen species‐mediated ER stress, compromised protein secretion, and eventually cancer cell death.
Redaporfin enriches in the ER and GA in human osteosarcoma cells.
Light activated redaporfin causes reactive oxygen species‐dependent perturbation of the ER and GA, coupled to irreversible inhibition of GA function, leading to reduced cytokine secretion.
Dissipation of the GA by brefeldin A or golgicide A can reduce the redaporfin‐mediated phototoxicity.
Localized production of reactive oxygen species at the GA is sufficient to kill cancer cells.
The antineoplastic photosensitizer redaporfin kills cancer cells via irreversible inactivation of endoplasmic reticulum and Golgi, paralyzing protein secretion and triggering mitochondrial cell death.
Bioluminescence (BL) and chemiluminescence (CL) are remarkable processes in which light is emitted due to (bio)chemical reactions. These reactions have attracted significant attention for various ...applications, such as biosensing, bioimaging, and biomedicine. Some of the most relevant and well-studied BL/CL systems are that of marine imidazopyrazine-based compounds, among which Coelenterazine is a prime example. Understanding the mechanisms behind efficient chemiexcitation is essential for the optimization and development of practical applications for these systems. Here, the CL of a fluorinated Coelenterazine analog was studied using experimental and theoretical approaches to obtain insight into these processes. Experimental analysis revealed that CL is more efficient under basic conditions than under acidic ones, which could be attributed to the higher relative chemiexcitation efficiency of an anionic dioxetanone intermediate over a corresponding neutral species. However, theoretical calculations indicated that the reactions of both species are similarly associated with both electron and charge transfer processes, which are typically used to explain efficiency chemiexcitation. So, neither process appears to be able to explain the relative chemiexcitation efficiencies observed. In conclusion, this study provides further insight into the mechanisms behind the chemiexcitation of imidazopyrazinone-based systems.
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