Medium Lethal Dose of Gamma Rays to Induce Mutations in Caribgrass (Eriochloa polystachya Kunth)

Universidad Nacional Agraria La Molina. Escuela de Posgrado. Maestría en Producción AnimalLos rayos gamma se pueden utilizar para el mejoramiento genético de las plantas y generar mutaciones que puedan ser útiles. La investigación se realizó con el objetivo de determinar la dosis letal media (DL50) para inducir mutaciones, con radiación gamma, en pasto janeiro (Eriochloa polystachya Kunth). Métodos: Se irradiaron 8 600 estolones de 8 cm de largo con un nudo, cortados de plantas maduras de más de seis meses de edad con dosis de 0; 25; 50; 75 y 100 Gray de rayos gamma Co60. Se evaluó el porcentaje de establecimiento, altura de planta y mortalidad de los estolones. Los datos fueron analizados a través del análisis de regresión lineal probabilística. Resultados: De acuerdo con la variable porcentaje de establecimiento, la DL50, es igual a 52,60 Gy para el genotipo estudiado, con R2 de 57,73. Conclusiones: Se concluye que la dosis media letal para inducir mutaciones en el pasto Janeiro (Eriochloa polystachya Kunth) se obtuvo con 52,60 Gy con R2 de 57,73.Gamma radiation can be used for genetic breeding of plants, and to produce useful mutations. This research was performed in order to determine the medium lethal dose (LD50) of gamma radiation in Caribgrass (Eriochloa polystachya Kunth). Methods: Overall, 8 600 stolons measuring 8 cm long, bearing a node, were cut from mature plants (over six month old), and were radiated with doses of 0, 25, 50, 75, and 100 Gray of gamma rays Co60. The establishment percentage, plant height, and stolon mortality were evaluated. The data were analyzed by probabilistic linear regression analysis. Results: According to variable percentage of establishment, LD50 was equal to 52.60 Gy, in the genotype studied, with an R2 of 57.73. Conclusions: The medium lethal dose to induce mutations of Caribgrass (Eriochloa polystachya Kunth) was achieved with 52.60 Gy

Improved functionalization of oleic acid-coated iron oxide nanoparticles for biomedical applications

Superparamagnetic iron oxide nanoparticles can providemultiple benefits for biomedical applications in aqueous environments such asmagnetic separation or magnetic resonance imaging. To increase the colloidal stability and allow subsequent reactions, the introduction of hydrophilic functional groups onto the particles’ surface is essential. During this process, the original coating is exchanged by preferably covalently bonded ligands such as trialkoxysilanes. The duration of the silane exchange reaction, which commonly takes more than 24 h, is an important drawback for this approach. In this paper, we present a novel method, which introduces ultrasonication as an energy source to dramatically accelerate this process, resulting in high-quality waterdispersible nanoparticles around 10 nmin size. To prove the generic character, different functional groups were introduced on the surface including polyethylene glycol chains, carboxylic acid, amine, and thiol groups. Their colloidal stability in various aqueous buffer solutions as well as human plasma and serum was investigated to allow implementation in biomedical and sensing applications.status: publishe

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Biomimetic Sol–Gel Synthesis of TiO₂ and SiO₂ Nanostructures

We report the heptapeptide-mediated biomineralization of titanium dioxide nanoparticles from titanium alkoxides. We evaluated the influence of pH on the biomineralized products and found that nanostructured TiO₂ was formed in the absence of external ions (water only) at pH ∼ 6.5. Several variants (mutants) of the peptides with different properties (i.e., different charges, isoelectric points (p<i>I</i>s), and sequences) were designed and tested in biomineralization experiments. Acid-catalyzed experiments were run using the H1 (HKKPSKS) peptide at room temperature, which produced anatase nanoparticles (∼5 nm in size) for the first time via a heptapeptide and sol–gel approach. In addition, the peptide H1 was used to synthesize SiO₂ nanoparticles. The influence of the pH and the added ions were monitored: at higher pH levels (8–9), SiO₂ nanoparticles (20–30 nm in size) were obtained. In addition, whereas borate and Tris ions allowed the formation of colloidal systems, phosphate ions were unable to produce sols. The results presented here demonstrate that biomineralization depends on the sequence and charge of the peptide, and ions in solution can optimize the formation of nanostructures