Controls of soil spatial variability in a dry tropical forest

We examined the roles of lithology, topography, vegetation and fire in generating local-scale (= 1 cm diameter at breast height (DBH), and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling) in a permanent 50-ha plot. Unlike classic catenas, lower elevation soils had lesser moisture, plant-available Ca, Cu, Mn, Mg, Zn, B, clay and total C. The distribution of plant-available Ca, Cu, Mn and Mg appeared to largely be determined by the whole-rock chemical composition differences between amphibolites and hornblende-biotite gneisses. Amphibolites were associated with summit positions, while gneisses dominated lower elevations, an observation that concurs with other studies in the region which suggest that hillslope-scale topography has been shaped by differential weathering of lithologies. Neither NO3--N nor NH4+-N was explained by the basal area of trees belonging to Fabaceae, a family associated with N-fixing species, and no long-term effects of fire on soil parameters were detected. Local-scale lithological variation is an important first-order control over soil variability at the hillslope scale in this SDTF, by both direct influence on nutrient stocks and indirect influence via control of local relief

Extractive Visible Spectrophotometric Determination of Lamotrigine in Pure and Pharmaceutical Formulations

Abstract: Two simple, sensitive, accurate and economical spectrophotometric methods (A & B) for the determination of lamotrigine (LMT) in pure and pharmaceutical formulations (tablets) are described in the present work. Method A is based on the formation of coloured ion-association complex between lamotrigine and tropaeolineo-oo (TPooo) with absorption maximum at 485 nm and obeys Beer's law in the concentration range of 5-25 µg/mL. Formation of ion-association complex between lamotrigine and alizarine Red S (ARS) to yield a coloured chromogen exhibiting absorption maximum at 440 nm (Method B) obeying Beer's law in the concentration range of 5-25 µg/mL forms the basis of Method B. The two methods have been validated statistically through recovery studies. The results are compared with those obtained using UV spectrophotometric method (Reference method) in chloroform at 260 nm

Polymorphisms in the BER and NER pathways and their influence on survival and toxicity in never-smokers with lung cancer

Polymorphisms in DNA repair pathways may play a relevant role in lung cancer survival in never-smokers. Furthermore, they could be implicated in the response to chemotherapy and toxicity of platinum agents. The aim of this study was to evaluate the influence of various genetic polymorphisms in the BER and NER DNA repair pathways on survival and toxicity in never-smoker LC patients. The study included never-smokers LC cases diagnosed from 2011 through 2019, belonging to the Lung Cancer Research In Never Smokers study. A total of 356 never-smokers cases participated (79% women; 83% adenocarcinoma and 65% stage IV). Survival at 3 and 5 years from diagnosis was not associated with genetic polymorphisms, except in the subgroup of patients who received radiotherapy or chemo-radiotherapy, and presented with ERCC1 rs3212986 polymorphism. There was greater toxicity in those presenting OGG1 rs1052133 (CG) and ERCC1 rs11615 polymorphisms among patients treated with radiotherapy or chemo-radiotherapy, respectively. In general, polymorphisms in the BER and NER pathways do not seem to play a relevant role in survival and response to treatment among never-smoker LC patients

Comprehensive cross-platform comparison of methods for non-invasive EGFR mutation testing : results of the RING observational trial.

Abstract Several platforms for noninvasive EGFR testing are currently used in the clinical setting with sensitivities ranging from 30% to 100%. Prospective studies evaluating agreement and sources for discordant results remain lacking. Herein, seven methodologies including two next-generation sequencing (NGS)-based methods, three high-sensitivity PCR-based platforms, and two FDA-approved methods were compared using 72 plasma samples, from EGFR-mutant non-small-cell lung cancer (NSCLC) patients progressing on a first-line tyrosine kinase inhibitor (TKI). NGS platforms as well as high-sensitivity PCR-based methodologies showed excellent agreement for EGFR-sensitizing mutations (K = 0.80-0.89) and substantial agreement for T790M testing (K = 0.77 and 0.68, respectively). Mutant allele frequencies (MAFs) obtained by different quantitative methods showed an excellent reproducibility (intraclass correlation coefficients 0.86-0.98). Among other technical factors, discordant calls mostly occurred at mutant allele frequencies (MAFs) ≤ 0.5%. Agreement significantly improved when discarding samples with MAF ≤ 0.5%. EGFR mutations were detected at significantly lower MAFs in patients with brain metastases, suggesting that these patients risk for a false-positive result. Our results support the use of liquid biopsies for noninvasive EGFR testing and highlight the need to systematically report MAFs. Keywords: NGS; circulating free DNA; epidermal growth factor receptor; non-small-cell lung cancer; osimertinib; tyrosine kinase inhibitor

Energy scavenging from insect flight

This paper reports the design, fabrication and testing of an energy scavenger that generates power from the wing motion of a Green June Beetle (C otinis nitida ) during its tethered flight. The generator utilizes non-resonant piezoelectric bimorphs operated in the d 31 bending mode to convert mechanical vibrations of a beetle into electrical output. The available deflection, force, and power output from oscillatory movements at different locations on a beetle are measured with a meso-scale piezoelectric beam. This way, the optimum location to scavenge energy is determined, and up to ~115 µW total power is generated from body movements. Two initial generator prototypes were fabricated, mounted on a beetle, and harvested 11.5 and 7.5 µW in device volumes of 11.0 and 5.6 mm 3 , respectively, from 85 to 100 Hz wing strokes during the beetle's tethered flight. A spiral generator was designed to maximize the power output by employing a compliant structure in a limited area. The necessary technology needed to fabricate this prototype was developed, including a process to machine high-aspect ratio devices from bulk piezoelectric substrates with minimum damage to the material using a femto-second laser. The fabricated lightweight spiral generators produced 18.5–22.5 µW on a bench-top test setup mimicking beetles' wing strokes. Placing two generators (one on each wing) can result in more than 45 µW of power per insect. A direct connection between the generator and the flight muscles of the insect is expected to increase the final power output by one order of magnitude.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90804/1/0960-1317_21_9_095016.pd

Curcuminoid Binding to Embryonal Carcinoma Cells: Reductive Metabolism, Induction of Apoptosis, Senescence, and Inhibition of Cell Proliferation

Curcumin preparations typically contain a mixture of polyphenols, collectively referred to as curcuminoids. In addition to the primary component curcumin, they also contain smaller amounts of the co-extracted derivatives demethoxycurcumin and bisdemethoxycurcumin. Curcuminoids can be differentially solubilized in serum, which allows for the systematic analysis of concentration-dependent cellular binding, biological effects, and metabolism. Technical grade curcumin was solubilized in fetal calf serum by two alternative methods yielding saturated preparations containing either predominantly curcumin (60%) or bisdemethoxycurcumin (55%). Continual exposure of NT2/D1 cells for 4–6 days to either preparation in cell culture media reduced cell division (1–5 µM), induced senescence (6–7 µM) or comprehensive cell death (8–10 µM) in a concentration-dependent manner. Some of these effects could also be elicited in cells transiently exposed to higher concentrations of curcuminoids (47 µM) for 0.5–4 h. Curcuminoids induced apoptosis by generalized activation of caspases but without nucleosomal fragmentation. The equilibrium binding of serum-solubilized curcuminoids to NT2/D1 cells incubated with increasing amounts of curcuminoid-saturated serum occurred with apparent overall dissociation constants in the 6–10 µM range. However, the presence of excess free serum decreased cellular binding in a hyperbolic manner. Cellular binding was overwhelmingly associated with membrane fractions and bound curcuminoids were metabolized in NT2/D1 cells via a previously unidentified reduction pathway. Both the binding affinities for curcuminoids and their reductive metabolic pathways varied in other cell lines. These results suggest that curcuminoids interact with cellular binding sites, thereby activating signal transduction pathways that initiate a variety of biological responses. The dose-dependent effects of these responses further imply that distinct cellular pathways are sequentially activated and that this activation is dependent on the affinity of curcuminoids for the respective binding sites. Defined serum-solubilized curcuminoids used in cell culture media are thus suitable for further investigating the differential activation of signal transduction pathways

Actividades de estimulación visual para la lectura

Licenciado en Ciencias de la Educación. Educación PrimariaCuenc