Phytotoxic activity of Ulex europaeus, an invasive plant on Chilean ecosystems: separation and identification of potential allelochemicals.

Despite its worldwide relevance as an invasive plant, there are few studies on Ulex europaeus (gorse) and its allelopathic activity is almost unexplored. The allelochemical profile of gorse was analysed through methanolic extract of pods and roots, and its phytotoxic effects on Lactuca sativa germination. The methanolic extract of pods had no effect in germination, while extract of roots resulted in a U-shaped dose-response curve: reducing the germination at concentration 0.5 mg mL-1. GC-MS analysis detected compounds with proven antimicrobial and antioxidant activities in the pods and cytotoxic compounds in the roots, which could explain the bioassay results. The quinolizidine alkaloids (QAs) composition was evaluated to predict possible biological functions. It showed the presence of QAs in gorse that are absent in their native range, indicating broad defense strategies against bacteria, fungi, plants, and insects in the Chilean ecosystem. This could explain the superiority of gorse in the invaded areas.

Metabolomics analysis reveals a modified amino acid metabolism that correlates with altered oxygen homeostasis in COVID-19 patients.

We identified the main changes in serum metabolites associated with severe (n = 46) and mild (n = 19) COVID-19 patients by gas chromatography coupled to mass spectrometry. The modified metabolic profiles were associated to an altered amino acid catabolism in hypoxic conditions. Noteworthy, three α-hydroxyl acids of amino acid origin increased with disease severity and correlated with altered oxygen saturation levels and clinical markers of lung damage. We hypothesize that the enzymatic conversion of α-keto-acids to α- hydroxyl-acids helps to maintain NAD recycling in patients with altered oxygen levels, highlighting the potential relevance of amino acid supplementation during SARS-CoV-2 infection.

Oleamide Induces Cell Death in Glioblastoma RG2 Cells by a Cannabinoid Receptor-Independent Mechanism.

The endocannabinoid system has been associated with antiproliferative effects in several types of tumors through cannabinoid receptor-mediated cell death mechanisms. Oleamide (ODA) is a CB1/CB2 agonist associated with cell growth and migration by adhesion and/or ionic signals associated with Gap junctions. Antiproliferative mechanisms related to ODA remain unknown. In this work, we evaluated the effects of ODA on cell viability and morphological changes in a rat RG2 glioblastoma cell line and compared these effects with primary astrocyte cultures from 8-day postnatal rats. RG2 and primary astrocyte cultures were treated with ODA at increasing concentrations (25, 50, 100, and 200 µM) for different periods of time (12, 24, and 48 h). Changes in RG2 cell viability and morphology induced by ODA were assessed by viability/mitochondrial activity test and phase contrast microscopy, respectively. The ratios of necrotic and apoptotic cell death, and cell cycle alterations, were evaluated by flow cytometry. The roles of CB1 and CB2 receptors on ODA-induced changes were explored with specific receptor antagonists. ODA (100 µM) induced somatic damage, detachment of somatic bodies, cytoplasmic polarization, and somatic shrinkage in RG2 cells at 24 and 48 h. In contrast, primary astrocytes treated at the same ODA concentrations exhibited cell aggregation but not cell damage. ODA (100 µM) increased apoptotic cell death and cell arrest in the G1 phase at 24 h in the RG2 line. The effects induced by ODA on cell viability of RG2 cells were independent of CB1 and CB2 receptors or changes in intracellular calcium transient. Results of this novel study suggest that ODA exerts specific antiproliferative effects on RG2 glioblastoma cells through unconventional apoptotic mechanisms not involving canonical signals.

Gel Phase 1,2-Distearoyl-sn-glycero-3-phosphocholine-Based Liposomes Are Superior to Fluid Phase Liposomes at Augmenting Both Antigen Presentation on Major Histocompatibility Complex Class II and Costimulatory Molecule Display by Dendritic Cells in Vitro.

Lipid-based nanoparticles have in recent years attracted increasing attention as pharmaceutical carriers. In particular, reports of them having inherent adjuvant properties combined with their ability to protect antigen from degradation make them suitable as vaccine vectors. However, the physicochemical profile of an ideal nanoparticle for vaccine delivery is still poorly defined. Here, we used an in vitro dendritic cell assay to assess the immunogenicity of a variety of liposome formulations as vaccine carriers and adjuvants. Using flow cytometry, we investigated liposome-assisted antigen presentation as well as the expression of relevant costimulatory molecules on the cell surface. Cytokine secretion was further evaluated with an enzyme-linked immunosorbent assay (ELISA). We show that liposomes can successfully enhance antigen presentation and maturation of dendritic cells, as compared to vaccine fusion protein (CTA1-3Eα-DD) administered alone. In particular, the lipid phase state of the membrane was found to greatly influence the vaccine antigen processing by dendritic cells. As compared to their fluid phase counterparts, gel phase liposomes were more efficient at improving antigen presentation. They were also superior at upregulating the costimulatory molecules CD80 and CD86 as well as increasing the release of the cytokines IL-6 and IL-1ß. Taken together, we demonstrate that gel phase liposomes, while nonimmunogenic on their own, significantly enhance the antigen-presenting ability of dendritic cells and appear to be a promising way forward to improve vaccine immunogenicity.

Free Radical-Scavenging Capacities, Phenolics and Capsaicinoids in Wild Piquin Chili (Capsicum annuum var. Glabriusculum).

The total phenolic compounds content, free radical-scavenging capacity and capsaicinoid content in populations of wild Piquin chili (C. annuum) were studied. Aqueous and hydroalcoholic extracts from nine ecotypes were evaluated. High contents of phenolic compounds and free radical-scavenging capacities were observed for both extracts; however, the values that were found for the hydroalcoholic phase were substantially higher. LC-MS analysis allowed for the detection of 32 compounds, where apigenin-8-C-glucoside followed by vanillic acid 1-O-ß-o-glucopyranosylester (Isomer I or II) and 7-ethoxy-4-methylcoumarin were the most widely distributed; they were found in more than 89% of the ecotypes. The diversity of identified phenolic compounds was different among ecotypes, allowing them to be distinguished by chemical diversity, free radical-scavenging capacities and heat Scoville units. The total capsaicinoid content was higher in Population I (23.5 mg/g DW) than in Populations II and III, which had contents of 15.3 and 10.7 mg/g DW, respectively. This variability could lead to phytochemical exploitation and the conservation of the natural populations of wild chili.

The Impact of Discharge Disposition on Episode-of-Care Reimbursement After Primary Total Hip Arthroplasty.

BACKGROUND: Total joint arthroplasty (TJA) accounts for more Medicare expenditure than any other inpatient procedure. The Comprehensive Care for Joint Replacement model was introduced to decrease cost and improve quality in TJA. The largest portion of episode-of-care costs occurs after discharge. This study sought to quantify the cost variation of primary total hip arthroplasty (THA) according to discharge disposition. METHODS: The Medicare and Humana claims databases were used to extract charges and reimbursements to compare day-of-surgery and 91-day postoperative costs simulating episode-of-care reimbursements. Of the patients who underwent primary THA, 257,120 were identified (204,912 from Medicare and 52,208 from Humana). Patients were stratified by discharge disposition: home with home health, skilled nursing facility, or inpatient rehabilitation facility. RESULTS: There is a significant difference in the episode-of-care costs according to discharge disposition, with discharge to an inpatient rehabilitation facility the most costly and discharge to home the least costly. CONCLUSION: Postdischarge costs represent a sizeable portion of the overall expense in THA, and optimizing patients to allow safe discharge to home may help reduce the cost of THA.

Lipodisks integrated with weak affinity chromatography enable fragment screening of integral membrane proteins.

Membrane proteins constitute the largest class of drug targets but they present many challenges in drug discovery. Importantly, the discovery of potential drug candidates is hampered by the limited availability of efficient methods for screening drug-protein interactions. In this work we present a novel strategy for rapid identification of molecules capable of binding to a selected membrane protein. An integral membrane protein (human aquaporin-1) was incorporated into planar lipid bilayer disks (lipodisks), which were subsequently covalently coupled to porous derivatized silica and packed into HPLC columns. The obtained affinity columns were used in a typical protocol for fragment screening by weak affinity chromatography (WAC), in which one hit was identified out of a 200 compound collection. The lipodisk-based strategy, which ensures a stable and native-like lipid environment for the protein, is expected to work also with other membrane proteins and screening procedures.

Optogenetic stimulation of the auditory pathway.

Auditory prostheses can partially restore speech comprehension when hearing fails. Sound coding with current prostheses is based on electrical stimulation of auditory neurons and has limited frequency resolution due to broad current spread within the cochlea. In contrast, optical stimulation can be spatially confined, which may improve frequency resolution. Here, we used animal models to characterize optogenetic stimulation, which is the optical stimulation of neurons genetically engineered to express the light-gated ion channel channelrhodopsin-2 (ChR2). Optogenetic stimulation of spiral ganglion neurons (SGNs) activated the auditory pathway, as demonstrated by recordings of single neuron and neuronal population responses. Furthermore, optogenetic stimulation of SGNs restored auditory activity in deaf mice. Approximation of the spatial spread of cochlear excitation by recording local field potentials (LFPs) in the inferior colliculus in response to suprathreshold optical, acoustic, and electrical stimuli indicated that optogenetic stimulation achieves better frequency resolution than monopolar electrical stimulation. Virus-mediated expression of a ChR2 variant with greater light sensitivity in SGNs reduced the amount of light required for responses and allowed neuronal spiking following stimulation up to 60 Hz. Our study demonstrates a strategy for optogenetic stimulation of the auditory pathway in rodents and lays the groundwork for future applications of cochlear optogenetics in auditory research and prosthetics.

Induction of defensive response in Eucalyptus globulus plants and its persistence in vegetative propagation.

The expression of defensive compounds derived from secondary metabolism in plants of Eucalyptus globulus Labill, and the persistence of these in vegetative propagation was evaluated by gas chromatography with flame ionization (GC-FID) and mass spectrometry (MS). The plants were induced by attack from the insect Ctenarytaina eucalypti ("blue gum psyllid") and by mechanical damage. Defense responses were activated in plants for the different types of tested induction. We identified four defensive compounds present in the leaves of plants induced in entomological form (beta-terpineol, aromadendrene, caryophyllene-oxide and eremophilene); all remained in the vegetative propagation. After mechanical induction, we identified three compounds (beta-terpineol, aromadendrene and ledol), of which ledol and aromadendrene persisted in the vegetative propagation. Virtually all the compounds detected, in addition to persisting in the vegetative propagation, showed specificity for the induction type, whether entomological or mechanical, except for aromadendrene, which was expressed in both types of induction.

Current pharmacologic management of pediatric heart failure in congenital heart disease.

Pharmacologic therapy represents the mainstay of treatment for heart failure in children. However, medical therapy for this population is not widely standardized. This is mainly due to the heterogeneity of potential etiologies, the specific challenge of patients with univentricular physiology and the lack of evidence-based prospective randomized clinical trials in pediatric patients. In fact, most current strategies are based largely on extrapolated data from adult studies. Although the classic drugs for heart failure, i.e. diuretics, angiotensin-converting enzyme inhibitors, ß -blockers and cardiac glycosides, still play a major role in the treatment of pediatric heart failure, newer alternative therapies such as levosimendan and nesiritide are increasingly utilized with promising early results. A systematic literature search of PubMed and MEDLINE databases using relevant terms was performed. All clinical trials and relevant manuscripts about the current pharmacologic treatment of heart failure in the pediatric population were reviewed. New drugs such as levosimendan and nesiritide and the treatment of single-ventricle patients were also included.

Synchronicity of pollination and inoculation with Claviceps africana and its effects on pollen-pistil compatibility and seed production in sorghum.

Sorghum ergot (caused by Claviceps africana) is a disease that affects sorghum seed development and yield. The interaction between pollen tube growth and hyphal development determines whether ovaries will be fertilized or colonized. Thus their respective deposition times on the stigma are critical. The effect of the time interval between pollination and inoculation on stigma receptivity and seed production was measured under field conditions in the male-sterile line A9 at Montecillo, State of México (2240m altitude). Pollination and inoculation treatments, from simultaneous application to 2 and 4h difference, were imposed when all stigmas on the panicle had emerged. Control panicles were either only pollinated or only inoculated. Eighteen hours later, pollen grains that adhered to, and germinated within the stigma, pollen tubes in the style and ovary, and fertilized pistils were counted. Pistils showing some disease expression (germinated spores, mycelium growth, or tissue necrosis) at 18, 48, and 72h were recorded. The number of diseased florets was registered at the dough growth stage, while number of seeds, grain yield and 100-seeds weight was measured at the physiological maturity. The pathogen applied in a water suspension of macro and secondary conidia caused a decrease in stigma receptivity; the greatest decrease (40-60%) occurred when the pollen and the inoculum were deposited almost simultaneously, regardless of which was deposited first. The route of the pollen tube was also the route for fungal infection. On average, treatments first inoculated had 60% more diseased florets and 36% less grain yield, 30% fewer seeds and seed size decreased 8%, than those first pollinated.

Recombinant amaranth cystatin (AhCPI) inhibits the growth of phytopathogenic fungi.

Phytocystatins are cysteine proteinase inhibitors from plants implicated in defense mechanisms against insects and plant pathogens. We have previously characterized an amaranth cystatin cDNA and analyzed its response to different kinds of abiotic stress [37]. In order to characterize amaranth cystatin, the coding sequence was expressed in Escherichia coli using the pQE-2 vector. Recombinant cystatin was predominantly found in the soluble fraction of the cell extract. Large amounts (266 mgL(-1)) of pure recombinant protein were obtained by affinity chromatography in a single step of purification. The amaranth cystatin with a pI 6.8 and an apparent 28 kDa molecular mass inhibited papain (E.C.3.4.22.2) (Ki 115 nM), ficin (E.C.3.4.22.3) (Ki 325 nM) and cathepsin L (E.C.3.4.22.15) (Ki 12.7 nM) but not stem bromelain (E.C.3.4.22.32), and cathepsin B (E.C.3.4.22.1) activities, in colorimetric assays. Furthermore, it was able to arrest the fungal growth of Fusarium oxysporum, Sclerotium cepivorum and Rhyzoctonia solani. It was further demonstrated that recombinant AhCPI is a weak inhibitor of the endogenous cysteine proteinase activities in the fungal mycelium. These findings contribute to a better understanding of the amaranth cystatin activity and encourage further studies of this protein.

The lipid composition determines the kinetics of adhesion and spreading of liposomes on mercury electrodes.

The dependence of membrane properties on their composition was studied by following the adhesion and spreading of unilamellar and multilamellar liposomes on static mercury electrodes with the help of chronoamperometry. The analysis of the peak-shaped signals allows determining the kinetic parameters of the three-step adhesion-spreading process. The presence of cholesterol in the membrane stabilizes the bilayer in the liquid-crystalline phase, and destabilizes the gel phase. The kinetic parameters also show the effect of superlattice formation in the DMPC-cholesterol system. The detergent triton X-100 is only incorporated in the liquid-crystalline DMPC membranes, and it is expelled to the solution when the membrane is transformed to the gel phase. In the liquid-crystalline membrane, it enhances the adhesion-spreading of liposomes on mercury. The lytic peptides mastoparan X and melittin affect the adhesion-spreading in a similar manner. For the rupture-spreading step, their effect is explained by pore formation. The results obtained with lecithins of different length suggest that the bilayer opening process has much in common with flip-flop translocations. For this process the activation energies were found to be independent of the chain length of the lecithin molecules, while the preexponential factor in the Arrhenius equation decreases drastically for longer chains.

Eritema migratorio como presentación clínica de larva migrans cutánea en la ciudad de México / Migratory Erytema as a clinical presentation of cutaneous larva migrans in Mexico City

La infección por larva migrans cutánea se presenta habitualmente como una erupción dérmica serpenginosa y pruriginosa debida a la penetración de la piel en túnel por larvas de nematelmintos. Esta parasitosis es endémica en zona tropicales, sin embargo se describen cada vez más casos en zonas urbanas. El diagnóstico de esta entidad es clínico, pero es frecuente que se confunda con enfermedades reumatológicas, infecciosas, vasculares o dermatológicas; especialmente cuando su presentación es como eritema migratorio. En este trabajo se revisa la presentación clínica y el tratamiento de 18 casos con infección por larva migrans cutánea