Fluorescence emission and enhanced photochemical stability of Zn-5-triethyl ammonium methyl salicylidene ortho-phenylendiiminate interacting with native DNA

The photophysical and photochemical properties of the cationic Zn^II complex of 5-triethyl ammonium methyl salicylidene ortho-phenylendiimine (ZnL²⁺) interacting with native DNA were investigated by steady state and time-resolved fluorescence spectroscopies. Experimental results indicate that, in the presence of DNA, ZnL²⁺ is efficiently protected from a photochemical process, which occurs when it is in the free state dispersed in aqueous solution. The analysis of the absorption and emission spectra of ZnL²⁺, both stored in the dark and after exposure to tungsten lamp light for 24 h, corroborated by quantum chemical calculations, allowed us to point out that ZnL²⁺ undergoes a photoinduced two-electron oxidation process. According to this picture, the protective action of DNA toward the intercalated ZnL²⁺ was attributed to an effective inhibition of the ZnL²⁺ photooxidation. In this context, it can be considered that DNA-intercalated ZnL²⁺ is located in a region more hydrophobic than that sensed in the bulk water solvent. Moreover, by a thorough analysis of steady state and time-resolved fluorescence spectra, the interaction process can be consistently explained in terms of a complete intercalation of the complex molecules and that the polarity of the environment sensed by intercalated ZnL²⁺ is comprised between that of methanol and ethanol.     

Pressure affects the structure and the dynamics of the D-galactose/D-glucose-binding protein from Escherichia coli by perturbing the C-terminal domain of the protein

The effect of the pressure on the structure and stability of the D-galactose/D-glucose binding protein from Escherichia coli in the absence (GGBP) and in the presence (GGBP/Glc) of glucose was studied by Fourier transform infrared (FT-IR) spectroscopy and molecular dynamic (MD) simulations. FT-IR spectroscopy experiments showed that the protein beta-structures are more resistant than alpha-helices structures to pressure value increases. In addition, the infrared data indicated that the binding of glucose stabilizes the protein structure against high pressure values, and the protein structure does not completely unfold up to pressure values close to 9000 bar. MD simulations allow a prediction of the most probable configuration of the protein, consistent with the increasing pressures on the two systems. The detailed analysis of the structures at molecular level confirms that, among secondary structures, alpha-helices are more sensitive than beta-structures to the destabilizing effect of high pressure and that glucose is able to preserve the structure of the protein in the complex. Moreover, the evidence of the different resistance of the two domains of this protein to high pressure is investigated and explained at a molecular level, indicating the importance of aromatic amino acid in protein stabilization.     

Secretory traffic triggers the formation of tubular continuities across Golgi sub-compartments

The organization of secretory traffic remains unclear, mainly because of the complex structure and dynamics of the secretory pathway. We have thus studied a simplified system, a single synchronized traffic wave crossing an individual Golgi stack, using electron tomography. Endoplasmic-reticulum-to-Golgi carriers join the stack by fusing with cis cisternae and induce the formation of intercisternal tubules, through which they redistribute their contents throughout the stack. These tubules seem to be pervious to Golgi enzymes, whereas Golgi vesicles are depleted of both enzymes and cargo. Cargo then traverses the stack without leaving the cisternal lumen. When cargo exits the stack, intercisternal connections disappear. These findings provide a new view of secretory traffic that includes dynamic intercompartment continuities as key players.     

The locomotion of Babakotia radofilai inferred from epiphyseal and diaphyseal morphology of the humerus and femur

Palaeopropithecids, or “sloth lemurs,” are a diverse clade of large‐bodied Malagasy subfossil primates characterized by their inferred suspensory positional behavior. The most recently discovered genus of the palaeopropithecids is Babakotia, and it has been described as more arboreal than Mesopropithecus, but less than Palaeopropithecus. In this article, the within‐bone and between‐bones articular and cross‐sectional diaphyseal proportions of the humerus and femur of Babakotia were compared to extant lemurs, Mesopropithecus and Palaeopropithecus in order to further understand its arboreal adaptations. Additionally, a sample of apes and sloths (Choloepus and Bradypus) are included as functional outgroups composed of suspensory adapted primates and non‐primates. Results show that Babakotia and Mesopropithecus both have high humeral/femoral shaft strength proportions, similar to extant great apes and sloths and indicative of forelimb suspensory behavior, with Babakotia more extreme in this regard. All three subfossil taxa have relatively large femoral heads, also associated with suspension in modern taxa. However, Babakotia and Mesopropithecus (but not Palaeopropithecus) have relatively small femoral head surface area to shaft strength proportions suggesting that hind‐limb positioning in these taxa during climbing and other behaviors was different than in extant great apes, involving less mobility. Knee and humeral articular dimensions relative to shaft strengths are small in Babakotia and Mesopropithecus, similar to those found in modern sloths and divergent from those in extant great apes and lemurs, suggesting more sloth‐like use of these joints during locomotion. Mesopropithecus and Babakotia are more similar to Choloepus in humerofemoral head and length proportions while Palaeopropithecus is more similar to Bradypus. These results provide further evidence of the suspensory adaptations of Babakotia and further highlight similarities to both extant suspensory primates and non‐primate slow arboreal climbers and hangers. J. Morphol. 277:1199–1218, 2016. © 2016 Wiley Periodicals, Inc.     

Quality Assessment and Circularity Potential of Recovery Systems for Household Plastic Waste

Plastic recycling is promoted in the transition toward a circular economy and a closed plastic loop, typically using mass‐based recycling targets. Plastic from household waste (HHW) is contaminated and heterogeneous, and recycled plastic from HHW often has a limited application range, due to reduced quality. To correctly assess the ability to close plastic loops via recycling, both plastic quantities and qualities need to be evaluated. This study defines a circularity potential representing the ability of a recovery system to close material loops assuming steady‐state market conditions. Based on an average plastic waste composition including impurities, 84 recovery scenarios representing a wide range of sorting schemes, source‐separation efficiencies, and material recovery facility (MRF) configurations and performances were assessed. The qualities of the recovered fractions were assessed based on contamination and the circularity potential calculated for each scenario in a European context. Across all scenarios, 17% to 100% of the generated plastic mass could be recovered, with higher source‐separation and MRF efficiencies leading to higher recovery. Including quality, however, at best 55% of the generated plastic was suitable for recycling due to contamination. Source‐separation, a high number of target fractions, and efficient MRF recovery were found to be critical. The circularity potential illustrated that less than 42% of the plastic loop can be closed with current technology and raw material demands. Hence, Europe is still far from able to close the plastic loop. When transitioning toward a circular economy, the focus should be on limiting impurities and losses through product design, technology improvement, and more targeted plastic waste management.     

Risk factors and outcomes of candidemia caused by biofilm-forming isolates in a tertiary care hospital

Background

Very few data exist on risk factors for developing biofilm-forming Candida bloodstream infection (CBSI) or on variables associated with the outcome of patients treated for this infection.

Methods and Findings

We identified 207 patients with CBSI, from whom 84 biofilm-forming and 123 non biofilm-forming Candida isolates were recovered. A case-case-control study to identify risk factors and a cohort study to analyze outcomes were conducted. In addition, two sub-groups of case patients were analyzed after matching for age, sex, APACHE III score, and receipt of adequate antifungal therapy. Independent predictors of biofilm-forming CBSI were presence of central venous catheter (odds ratio [OR], 6.44; 95% confidence interval [95% CI], 3.21–12.92) or urinary catheter (OR, 2.40; 95% CI, 1.18–4.91), use of total parenteral nutrition (OR, 5.21; 95% CI, 2.59–10.48), and diabetes mellitus (OR, 4.47; 95% CI, 2.03–9.83). Hospital mortality, post-CBSI hospital length of stay (LOS) (calculated only among survivors), and costs of antifungal therapy were significantly greater among patients infected by biofilm-forming isolates than those infected by non-biofilm-forming isolates. Among biofilm-forming CBSI patients receiving adequate antifungal therapy, those treated with highly active anti-biofilm (HAAB) agents (e.g., caspofungin) had significantly shorter post-CBSI hospital LOS than those treated with non-HAAB antifungal agents (e.g., fluconazole); this difference was confirmed when this analysis was conducted only among survivors. After matching, all the outcomes were still favorable for patients with non-biofilm-forming CBSI. Furthermore, the biofilm-forming CBSI was significantly associated with a matched excess risk for hospital death of 1.77 compared to non-biofilm-forming CBSI.

Conclusions

Our data show that biofilm growth by Candida has an adverse impact on clinical and economic outcomes of CBSI. Of note, better outcomes were seen for those CBSI patients who received HAAB antifungal therapy.     

Mesenchymal stromal cells from amniotic fluid are less prone to senescence compared to those obtained from bone marrow: An in vitro study

Mesenchymal stromal cells (MSCs) are considered to be an excellent source in regenerative medicine. They contain several cell subtypes, including multipotent stem cells. MSCs are of particular interest as they are currently being tested using cell and gene therapies for a number of human diseases. They represent a rare population in tissues; for this reason, they require, before being transplanted, an in vitro amplification. This process may induce replicative senescence, thus affecting differentiation and proliferative capacities. Increasing evidence suggests that MSCs from fetal tissues are significantly more plastic and grow faster than MSCs from bone marrow. Here, we compare amniotic fluid mesenchymal stromal cells (AF‐MSCs) and bone marrow mesenchymal stromal cells (BM‐MSCs) in terms of cell proliferation, surface markers, multidifferentiation potential, senescence, and DNA repair capacity. Our study shows that AF‐MSCs are less prone to senescence with respect to BM‐MSCs. Moreover, both cell models activate the same repair system after DNA damage, but AF‐MSCs are able to return to the basal condition more efficiently with respect to BM‐MSCs. Indeed, AF‐MSCs are better able to cope with genotoxic stress that may occur either during in vitro cultivation or following transplantation in patients. Our findings suggest that AF‐MSCs may represent a valid alternative to BM‐MSCs in regenerative medicine, and, of great relevance, the investigation of the mechanisms involved in DNA repair capacity of both AF‐MSCs and BM‐MSCs may pave the way to their rational use in the medical field.     

Carbonic anhydrase inhibitors. Inhibition of the β-class enzymes from the fungal pathogens Candida albicans and Cryptococcus neoformans with aliphatic and aromatic carboxylates

The inhibition of the β-carbonic anhydrases (CAs, EC 4.2.1.1) from the pathogenic fungi Cryptococcus neoformans (Can2) and Candida albicans (Nce103) with carboxylates such as the C1–C5 aliphatic carboxylates, oxalate, malonate, maleate, malate, pyruvate, lactate, citrate and some benzoates has been investigated. The best Can2 inhibitors were acetate and maleate (K_Is of 7.3–8.7 μM), whereas formate, acetate, valerate, oxalate, maleate, citrate and 2,3,5,6-tetrafluorobenzoate showed less effective inhibition, with K_Is in the range of 42.8–88.6 μM. Propionate, butyrate, malonate, l-malate, pyruvate, l-lactate and benzoate, were weak Can2 inhibitors, with inhibition constants in the range of 225–1267 μM. Nce103 was more susceptible to inhibition with carboxylates compared to Can2, with the best inhibitors (maleate, benzoate, butyrate and malonate) showing K_Is in the range of 8.6–26.9 μM. l-Malate and pyruvate together with valerate were the less efficient Nce103 inhibitors (K_Is of 87.7–94.0 μM), while the remaining carboxylates showed a compact behavior of efficient inhibitors (K_Is in the range of 35.1–61.6 μM). Notably the inhibition profiles of the two fungal β-CAs was very different from that of the ubiquitous host enzyme hCA II (belonging to the α-CA family), with maleate showing selectivity ratios of 113.6 and 115 for Can2 and Nce103, respectively, over hCA II inhibition. Therefore, maleate is a promising starting lead molecule for the development of better, low nanomolar, selective β-CA inhibitors.