Thermo-mechanical performance of nanostructured electrospun composites produced from poly(vinyl alcohol) and cellulosic compounds for potential uses as wound dressings

The purpose of this research was to analyze the morphology, thermal and mechanical properties of poly(vinyl alcohol) (PVA)-based electrospun mats reinforced with cellulose acetate (CA) or cellulose nanocrystalline (CNC) for potential applications in wound dressings. Bead-free and water-stable electrospun nanofibers made of blends of PVA and CA or CNC were successfully produced and crosslinked with glutaraldehyde vapor. Crosslinking slightly increased the nanofibers’ diameters in order of 43 and 13% for 80/20 PVA/CA and PVA/CNC electrospun mats, respectively, while maintaining their bead-free morphology. Thermogravimetry (TGA) and differential scanning calorimetry (DSC) evaluations were employed to determine the miscibility and the thermal response of the uncrosslinked and crosslinked mats, reporting a reduction in mass loss upon addition of CA and CNC and upon crosslinking process. Polymers’ powder and mats (before and after crosslinking) crystallinity was assessed by X-ray diffraction analysis (XRD). Crosslinked mats experienced a slight reduction in crystallinity compared to the uncrosslinked. Static and dynamic tensile strength tests revealed that CA and CNC doped mats enhanced the Young's modulus and lowered deformation at failure compared to pristine PVA electrospun mats. Data from storage modulus (E’) demonstrated the strength of the physical interactions formed between PVA and the cellulosic derivatives (either before and after crosslinking), highlighting the stiffness of CA (231.58 MPa for the 80/20 mat) and, particularly, CNC (742.04 MPa for the 80/20 mat). This research uncovered important information concerning the chemical and physical relation between polymeric matrices and additives, essential for the proper selection of materials for wound dressings production.Authors acknowledge the Portuguese Foundation for Science and Technology (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI) and the Portuguese Government (OE) for funding the project with reference PTDC/CTM-TEX/28074/2017 (POCI-01-0145-FEDER-028074). Authors also acknowledge project UIDP/00264/2020 of Centre for Textile Science and Technology (2C2T), funded by national funds through FCT/MCTES. M.A.T., D.P.F and H.P.F. also acknowledge FCT for PhD scholarship (SFRH/BD/148930/2019) and junior (CEECIND/02803/2017) and auxiliary researcher (2021.02720.CEECIND) contracts, respectively

Synthesis and thermal behaviour of an amorphous solid polymer electrolyte

In this study the synthesis of an amorphous polymer network, poly[oxymethylene-oligo(oxyethylene)], designated as aPEO, is described. This polymer has been characterized by gel permeation chromatography, thermal analysis, conductivity measurements, evaluation of electrochemical stability and nuclear magnetic resonance spectroscopy. The synthetic procedure developed permits partial fractionation of the product of the polymerization reaction. This linear macromolecule appears to be a promising polymer for application in batteries and electrochromic devices since it provides access to an amorphous polymer structure with good mechanical properties and promising electrochemical behavior.Fundação para a Ciência e a Tecnologia (FCT

Indoor school environment: easy and low cost to assess inorganic pollutants

Total particulate matter (TPM) was passively collected inside two classrooms of each of five elementary schools in Lisbon, Portugal. TPM was collected in polycarbonate filters with a 47 mm diameter, placed inside of uncovered plastic petri dishes. The sampling period was from 19 May to 22 June 2009 (35 days exposure) and the collected TPM masses varied between 0.2 mg and 0.8 mg. The major elements were Ca, Fe, Na, K, and Zn at μg level, while others were at ng level. Pearson′s correlation coefficients above 0.75 (a high degree of correlation) were found between several elements. Soil-related, traffic soil re-suspension and anthropogenic emission sources could be identified. Blackboard chalk was also identified through Ca large presence. Some of the determined chemical elements are potential carcinogenic. Quality control of the results showed good agreement as confirmed by the application of u-score test

Extended Spectrum Beta-Lactamase-Producing Gram-Negative Bacteria Recovered From an Amazonian Lake Near the City of Belém, Brazil

Aquatic systems have been described as antibiotic resistance reservoirs, where water may act as a vehicle for the spread of resistant bacteria and resistance genes. We evaluated the occurrence and diversity of third generation cephalosporin-resistant gram-negative bacteria in a lake in the Amazonia region. This water is used for human activities, including consumption after appropriate treatment. Eighteen samples were obtained from six sites in October 2014. Water quality parameters were generally within the legislation limits. Thirty-three bacterial isolates were identified as Escherichia (n = 7 isolates), Acinetobacter, Enterobacter, and Klebsiella (n = 5 each), Pseudomonas (n = 4), Shigella (n = 3), and Chromobacterium, Citrobacter, Leclercia, Phytobacter (1 isolate each). Twenty nine out of 33 isolates (88%) were resistant to most beta-lactams, except carbapenems, and 88% (n = 29) were resistant to antibiotics included in at least three different classes. Among the beta-lactamase genes inspected, the blaCTX–M was the most prevalent (n = 12 positive isolates), followed by blaTEM (n = 5) and blaSHV (n = 4). blaCTX–M–15 (n = 5), blaCTX–M–14 (n = 1) and blaCTX–M–2 (n = 1) variants were detected in conserved genomic contexts: blaCTX–M–15 flanked by ISEcp1 and Orf477; blaCTX–M–14 flanked by ISEcp1 and IS903; and blaCTX–M–2 associated to an ISCR element. For 4 strains the transfer of blaCTX–M was confirmed by conjugation assays. Compared with the recipient, the transconjugants showed more than 500-fold increases in the MICs of cefotaxime and 16 to 32-fold increases in the MICs of ceftazidime. Two isolates (Escherichia coli APC43A and Acinetobacter baumannii APC25) were selected for whole genome analysis. APC43A was predicted as a E. coli pathogen of the high-risk clone ST471 and serotype O154:H18. blaCTX–M–15 as well as determinants related to efflux of antibiotics, were noted in APC43A genome. A. baumannii APC25 was susceptible to carbapenems and antibiotic resistance genes detected in its genome were intrinsic determinants (e.g., blaOXA–208 and blaADC–like). The strain was not predicted as a human pathogen and belongs to a new sequence type. Operons related to metal resistance were predicted in both genomes as well as pathogenicity and resistance islands. Results suggest a high dissemination of ESBL-producing bacteria in Lake Água Preta which, although not presenting characteristics of a strongly impacted environment, contains multi-drug resistant pathogenic strains

Pathogenesis of reproductive failure induced by Trypanosoma vivax in experimentally infected pregnant ewes

The present study was aimed at investigating the effect of experimental infection by Trypanosoma vivax in different\ud stages of pregnancy, determining the pathogenesis of reproductive failure, and confirming transplacental\ud transmission. We used 12 pregnant ewes distributed into four experimental groups: G1, was formed by three ewes\ud infected with T. vivax in the first third of pregnancy (30 days); G2 comprised three infected ewes in the final third of\ud pregnancy (100 days); G3 and G4 were composed of three non-infected ewes with the same gestational period,\ud respectively. Each ewe of G1 and G2 was inoculated with 1.25 × 105 tripomastigotes. Clinical examination,\ud determination of parasitemia, serum biochemistry (albumin, total protein, glucose, cholesterol, and urea), packed\ud cell volume (PCV), serum progesterone, and pathological examination were performed. Placenta, amniotic fluid,\ud blood and tissues from the fetuses and stillbirths were submitted to PCR. Two ewes of G1 (Ewe 1 and 3) presented\ud severe infection and died in the 34th and 35th days post-infection (dpi), respectively; but both fetuses were\ud recovered during necropsy. In G2, Ewe 5 aborted two fetuses on the 130th day (30 dpi) of pregnancy; and Ewe 6\ud aborted one fetus in the 140th day (40 dpi) of gestation. Ewes 2 and 4 delivered two weak lambs that died five\ud days after birth. Factors possibly involved with the reproductive failure included high parasitemia, fever, low PCV,\ud body score, serum glucose, total protein, cholesterol, and progesterone. Hepatitis, pericarditis, and encephalitis were\ud observed in the aborted fetuses. The presence of T. vivax DNA in the placenta, amniotic fluid, blood, and tissues\ud from the fetuses confirms the transplacental transmission of the parasite. Histological lesion in the fetuses and\ud placenta also suggest the involvement of the parasite in the etiopathogenesis of reproductive failure in ewes

A Nanostructured Lipid System to Improve the Oral Bioavailability of Ruthenium(II) Complexes for the Treatment of Infections Caused by Mycobacterium tuberculosis

Tuberculosis (TB) is an infectious, airborne disease caused by the bacterium Mycobacterium tuberculosis that mainly affects the lungs. Fortunately, tuberculosis is a curable disease, and in recent years, death rates for this disease have decreased. However, the existence of antibiotic-resistant strains and the occurrence of co-infections with human immunodeficiency virus (HIV), have led to increased mortality in recent years. Another area of concern is that one-third of the world′s population is currently infected with M. tuberculosis in its latent state, serving as a potential reservoir for active TB. In an effort to address the failure of current TB drugs, greater attention is being given to the importance of bioinorganic chemistry as an ally in new research into the development of anti-TB drugs. Ruthenium (Ru) is a chemical element that can mimic iron (Fe) in the body. In previous studies involving the following heteroleptic Ru complexes, [Ru(pic)(dppb)(bipy)]PF6 (SCAR1), [Ru(pic)(dppb)(Me-bipy)]PF6 (SCAR2), [Ru(pic)(dppb)(phen)]PF6 (SCAR4), cis-[Ru(pic)(dppe)2]PF6 (SCAR5), and [Ru(pic)(dppe)(phen)]PF6 (SCAR7), we observed excellent anti-TB activity, moderate cell-toxicity, and a lack of oral bioavailability in an in vivo model of these complexes. Therefore, the objective of this study was to evaluate the toxicity and oral bioavailability of these complexes by loading them into a nanostructured lipid system. The nanostructured lipid system was generated using different ratios of surfactant (soybean phosphatidylcholine, Eumulgin®, and sodium oleate), aqueous phase (phosphate buffer with a concentration of 1X and pH 7.4), and oil (cholesterol) to generate a system for the incorporation of Ru(II) compounds. The anti-TB activity of the compounds was determined using a microdilution assay with Resazurin (REMA) against strains of M. tuberculosis H37Rv and clinical isolates resistant. Cytotoxicity assay using J774.A1 cells (ATCC TIB-67) and intra-macrophage activity were performed. The oral bioavailability assay was used to analyze blood collected from female BALB/C mice. Plasma collected from the same mice was analyzed via inductively coupled plasma mass spectrometry (ICP-MS) to quantify the number of Ru ions. The complexes loaded into the nanostructured lipid system maintained in vitro activity and toxicity was found to be reduced compared with the compounds that were not loaded. The complexes showed intra-macrophagic activity and were orally bioavailable

Pathogenesis of reproductive failure induced by Trypanosoma vivax in experimentally infected pregnant ewes

The present study was aimed at investigating the effect of experimental infection by Trypanosoma vivax in different stages of pregnancy, determining the pathogenesis of reproductive failure, and confirming transplacental transmission. We used 12 pregnant ewes distributed into four experimental groups: G1, was formed by three ewes infected with T. vivax in the first third of pregnancy (30 days); G2 comprised three infected ewes in the final third of pregnancy (100 days); G3 and G4 were composed of three non-infected ewes with the same gestational period, respectively. Each ewe of G1 and G2 was inoculated with 1.25 × 105 tripomastigotes. Clinical examination, determination of parasitemia, serum biochemistry (albumin, total protein, glucose, cholesterol, and urea), packed cell volume (PCV), serum progesterone, and pathological examination were performed. Placenta, amniotic fluid, blood and tissues from the fetuses and stillbirths were submitted to PCR. Two ewes of G1 (Ewe 1 and 3) presented severe infection and died in the 34th and 35th days post-infection (dpi), respectively; but both fetuses were recovered during necropsy. In G2, Ewe 5 aborted two fetuses on the 130th day (30 dpi) of pregnancy; and Ewe 6 aborted one fetus in the 140th day (40 dpi) of gestation. Ewes 2 and 4 delivered two weak lambs that died five days after birth. Factors possibly involved with the reproductive failure included high parasitemia, fever, low PCV, body score, serum glucose, total protein, cholesterol, and progesterone. Hepatitis, pericarditis, and encephalitis were observed in the aborted fetuses. The presence of T. vivax DNA in the placenta, amniotic fluid, blood, and tissues from the fetuses confirms the transplacental transmission of the parasite. Histological lesion in the fetuses and placenta also suggest the involvement of the parasite in the etiopathogenesis of reproductive failure in ewes.The authors would like to acknowledge the Federal Rural University of the Semiarid (UFERSA), University of São Paulo (USP) and Federal University of Minas Gerais (UFMG) contribution to the provision of laboratories and the availability of the structure