Photochemical Control of Network Topology in PEG Hydrogels.

Hydrogels are often synthesized through photoinitiated step-, chain-, and mixed-mode polymerizations, generating diverse network topologies and resultant material properties that depend on the underlying network connectivity. While many photocrosslinking reactions are available, few afford controllable connectivity of the hydrogel network. Herein, a versatile photochemical strategy is introduced for tuning the structure of poly(ethylene glycol) (PEG) hydrogels using macromolecular monomers functionalized with maleimide and styrene moieties. Hydrogels are prepared along a gradient of topologies by varying the ratio of step-growth (maleimide dimerization) to chain-growth (maleimide-styrene alternating copolymerization) network-forming reactions. The initial PEG content and final network physical properties (e.g., modulus, swelling, diffusivity) are tailored in an independent manner, highlighting configurable gel mechanics and reactivity. These photochemical reactions allow high-fidelity photopatterning and 3D printing and are compatible with 2D and 3D cell culture. Ultimately, this photopolymer chemistry allows facile control over network connectivity to achieve adjustable material properties for broad applications.

[Seroprevalence of hepatitis B in adult population of a district of Cajamarca]. / Seroprevalencia de hepatitis B en población adulta de un distrito de Cajamarca.

INTRODUCTION: Hepatitis B is a transmissible disease, it is estimated that globally more than two billion people in the world have been infected with hepatitis B virus, of which 350 million are chronic carriers of hepatitis B surface antigen, and this chronic infection causes cirrhosis and liver cancer. In Peru, hyperendemic zones have been detected in the country's jungle. Cajamarca is the third department with the highest rates of liver and bile duct cancer. Celendín is a district located in Cajamarca, which borders the jungle, and maintains a high contact with it for trade and tourism. There have been no previous studies of this virus in Cajamarca ́s population. OBJECTIVE: to determine if there is a high seroprevalence of the hepatitis B virus in the adult population of the Celendín-Cajamarca district, in 2018. MATERIAL AND METHODS: a cross-sectional study was carried out in 404 inhabitants of the Celendín district: a venous blood sample was taken to search for hepatitis B surface antigen and antibody, both by ELISA technique, and a survey was applied which included sociodemographic factors and associated risk factors. RESULTS: it was obtained that 1.24% (n=5) asymptomatic habitants were positive for the surface antigen of hepatitis B. The age over sixty five years was associated with the antigen positivity. 67.86% of the population included, do not have protective levels of antibodies against the hepatitis B virus, of which 10% even refer to being vaccinated. CONCLUSIONS: there is a low seroprevalence of the hepatitis B virus in the population of the district of Celendín-Cajamarca in 2018. More than half of the population does not have protection for this virus, many even when vaccinated.

Seroprevalencia de hepatitis B en población adulta de un distrito de Cajamarca

Introducción : La hepatitis B es una enfermedad transmisible, se estima que globalmente más de dos mil millones de habitantes del mundo han sido infectados por el virus de la hepatitis B (VHB), de los cuales 350 millones son portadores crónicos del antígeno de superficie de la hepatitis B (AgsHB). En el Perú, se han detectado zonas hiperendémicas en la selva del país. Esta infección crónica es una causa de cirrosis y cáncer de hígado. Cajamarca es el tercer departamento con más altos índices de cáncer de hígado y vías biliares del país. Celendín es un distrito ubicado en Cajamarca, que colinda con zonas hiperendémicas de la selva, y mantiene un elevado contacto con esta por comercio y turismo. No se han realizado estudios previos de este virus en esta población cajamarquina. Objetivo : Determinar si existe una alta seroprevalencia del HVB en población adulta del distrito de Celendín-Cajamarca. Evaluar la protección inmunológica de la población hacia este virus. Materiales y métodos: Se realizó un estudio transversal en 404 pobladores del distrito de Celendín, en los que se tomó una muestra de sangre venosa para buscar AgsHB, y anticuerpo del mismo (Anti-HBs), ambos mediante técnica ELISA, además se aplicó una encuesta que incluía factores sociodemográficos y factores de riesgo asociados. Resultados : se obtuvo que 1,24% (n=5) pobladores asintomáticos fueron positivos para AgsHB. Se asoció a la positividad del antígeno la edad mayor a 65 años. Un 67% de la población incluida no poseen niveles protectores de Anti-HBs, de los que un 10% refirió estar vacunado. Conclusiones : Existe una baja seroprevalencia del HVB en la población del distrito de Celendín - Cajamarca en el 2018. Más de la mitad de la población no posee protección para este virus, muchos incluso estando vacunados.

Introduction : Hepatitis B is a transmissible disease, it is estimated that globally more than two billion people in the world have been infected with hepatitis B virus, of which 350 million are chronic carriers of hepatitis B surface antigen, and this chronic infection causes cirrhosis and liver cancer. In Peru, hyperendemic zones have been detected in the country's jungle. Cajamarca is the third department with the highest rates of liver and bile duct cancer. Celendín is a district located in Cajamarca, which borders the jungle, and maintains a high contact with it for trade and tourism. There have been no previous studies of this virus in Cajamarca´s population. Objective : to determine if there is a high seroprevalence of the hepatitis B virus in the adult population of the Celendín-Cajamarca district, in 2018. Material and methods : a cross-sectional study was carried out in 404 inhabitants of the Celendín district: a venous blood sample was taken to search for hepatitis B surface antigen and antibody, both by ELISA technique, and a survey was applied which included sociodemographic factors and associated risk factors. Results: it was obtained that 1.24% (n=5) asymptomatic habitants were positive for the surface antigen of hepatitis B. The age over sixty five years was associated with the antigen positivity. 67.86% of the population included, do not have protective levels of antibodies against the hepatitis B virus, of which 10% even refer to being vaccinated. Conclusions : there is a low seroprevalence of the hepatitis B virus in the population of the district of Celendín-Cajamarca in 2018. More than half of the population does not have protection for this virus, many even when vaccinated.

Lr67/Yr46 confers adult plant resistance to stem rust and powdery mildew in wheat.

KEY MESSAGE: We demonstrate that Lr67/Yr46 has pleiotropic effect on stem rust and powdery mildew resistance and is associated with leaf tip necrosis. Genes are designated as Sr55, Pm46 and Ltn3 , respectively. Wheat (Triticum aestivum) accession RL6077, known to carry the pleiotropic slow rusting leaf and yellow rust resistance genes Lr67/Yr46 in Thatcher background, displayed significantly lower stem rust (P. graminis tritici; Pgt) and powdery mildew (Blumeria graminis tritici; Bgt) severities in Kenya and in Norway, respectively, compared to its recurrent parent Thatcher. We investigated the resistance of RL6077 to stem rust and powdery mildew using Avocet × RL6077 F6 recombinant inbred lines (RILs) derived from two photoperiod-insensitive F3 families segregating for Lr67/Yr46. Greenhouse seedling tests were conducted with Mexican Pgt race RTR. Field evaluations were conducted under artificially initiated stem rust epidemics with Pgt races RTR and TTKST (Ug99 + Sr24) at Ciudad Obregon (Mexico) and Njoro (Kenya) during 2010-2011; and under natural powdery mildew epiphytotic in Norway at Ås and Hamar during 2011 and 2012. In Mexico, a mean reduction of 41 % on stem rust severity was obtained for RILs carrying Lr67/Yr46, compared to RILs that lacked the gene, whereas in Kenya the difference was smaller (16 %) but significant. In Norway, leaf tip necrosis was associated with Lr67/Yr46 and RILs carrying Lr67/Yr46 showed a 20 % reduction in mean powdery mildew severity at both sites across the 2 years of evaluation. Our study demonstrates that Lr67/Yr46 confers partial resistance to stem rust and powdery mildew and is associated with leaf tip necrosis. The corresponding pleiotropic, or tightly linked, genes, designated as Sr55, Pm46, and Ltn3, can be utilized to provide broad-spectrum durable disease resistance in wheat.

Lr68: a new gene conferring slow rusting resistance to leaf rust in wheat.

The common wheat cultivar Parula possesses a high level of slow rusting, adult plant resistance (APR) to all three rust diseases of wheat. Previous mapping studies using an Avocet-YrA/Parula recombinant inbred line (RIL) population showed that APR to leaf rust (Puccinia triticina) in Parula is governed by at least three independent slow rusting resistance genes: Lr34 on 7DS, Lr46 on 1BL, and a previously unknown gene on 7BL. The use of field rust reaction and flanking markers identified two F(6) RILs, Arula1 and Arula2, from the above population that lacked Lr34 and Lr46 but carried the leaf rust resistance gene in 7BL, hereby designated Lr68. Arula1 and Arula2 were crossed with Apav, a highly susceptible line from the cross Avocet-YrA/Pavon 76, and 396 F(4)-derived F(5) RILs were developed for mapping Lr68. The RILs were phenotyped for leaf rust resistance for over 2 years in Ciudad Obregon, Mexico, with a mixture of P. triticina races MBJ/SP and MCJ/SP. Close genetic linkages with several DNA markers on 7BL were established using 367 RILs; Psy1-1 and gwm146 flanked Lr68 and were estimated at 0.5 and 0.6 cM, respectively. The relationship between Lr68 and the race-specific seedling resistance gene Lr14b, located in the same region and present in Parula, Arula1 and Arula2, was investigated by evaluating the RILs with Lr14b-avirulent P. triticina race TCT/QB in the greenhouse. Although Lr14b and Lr68 homozygous recombinants in repulsion were not identified in RILs, γ-irradiation-induced deletion stocks that lacked Lr68 but possessed Lr14b showed that Lr68 and Lr14b are different loci. Flanking DNA markers that are tightly linked to Lr68 in a wide array of genotypes can be utilized for selection of APR to leaf rust.