Enhanced forward scattering of a cell in line optical tweezers with an astigmatic beam.

The line optical tweezers (LOT) has been proven to be an alternative technique to manipulating the biological cells because of the bigger potential compared with traditional optical tweezers with a highly focused spot. We deduce the 4 × 4 optical matrix of the astigmatic LOT to investigate the optical characteristics related to the systematic parameters. The comparison of the initial and scattered electric fields by the cell under the astigmatic and stigmatic LOT is implemented to illustrate that the forward scattered light from the astigmatic LOT is much stronger than that from the stigmatic LOT, so as to the cell deformations. It is demonstrated that the astigmatic LOT could provide a more efficient way to deform the cell not only in the focal plane, but also along the optical axis to screen large biomaterials in biomechanics.

Mathematical simulation of temperature distribution in tumor tissue and surrounding healthy tissue treated by laser combined with indocyanine green.

BACKGROUND: Photothermal therapy is a local treatment method for cancer and the heat energy generated from it could destroy the tumor cells. This study is aimed to investigate the temperature distribution in tumor tissue and surrounding health tissue of tumor bearing mice applying mathematical simulation model. Tumor bearing mice treated by laser combined with or without indocyanine green. Monte Carlo method and the Pennes bio-heat equation were used to calculate the light distribution and heat energy. COMSOL Multiphysic was adopted to construct three dimensional temperature distribution model. RESULTS: This study revealed that the data calculated by simulation model is in good agreement with the surface temperature monitored by infrared thermometer. Effected by the optical parameters and boundary conditions of tissue, the highest temperature of tissue treated by laser combined with indocyanine green was about 65 °C which located in tumor tissue and the highest temperature of tissue treated by laser was about 43 °C which located under the tumor tissue. The temperature difference was about 20 °C. Temperature distribution in tissue was not uniform. The temperature difference in different parts of tumor tissue raised up to 15 °C. The temperature of tumor tissue treated by laser combined with indocyanine green was about 20 °C higher than that of the surrounding healthy tissue. CONCLUSIONS: Reasonably good matching between the calculated temperature and the measured temperature was achieved, thus demonstrated great utility of our modeling method and approaches for deepening understand in the temperature distribution in tumor tissue and surrounding healthy tissue during the laser combined with photosensitizer. The simulation model could provide guidance and reference function for the effect of photothermal therapy.

Sex-specific maternal calcium requirements for the prevention of nonalcoholic fatty liver disease by altering the intestinal microbiota and lipid metabolism in the high-fat-diet-fed offspring mice.

The significance of maternal appropriate calcium intakes for energy metabolism in the offspring has been recognized. Nonalcoholic fatty liver disease (NAFLD) is considered as the hepatic manifestation of metabolic syndrome. So in this study, we proposed that there were long-term effects of maternal calcium status on the progress of NAFLD by altering the intestinal microbiota and lipid metabolism with attention to potential sex differences among the mouse offspring. Thirty-four-week female C57BL/6 J mice were subjected to obtain low, normal and high calcium reproductive diets throughout the gestation and lactation. After weaning, both the male and female mouse offspring were fed with the high-fat diet for 16 weeks, with the normal diet as control. Biochemical indicators in the plasma and hepatic tissue were measured using ELISA or enzymatic methods. The expression of lipid metabolism, inflammatory and fibrosis related genes was determined by RT-PCR. The intestinal microbiota was analyzed by 16S rRNA high-throughput sequencing. Maternal normal and low calcium intake could, respectively, inhibit the progress of high-fat diet induced NAFLD in the male and female mouse offspring, which was characterized by the least lipid droplets, inflammatory infiltration and fibrosis, the lowest concentrations of free fatty acids and triglyceridethe lowest expression of genes involving in de novo lipogenesis and the highest expression of genes related to lipid oxidation and  hydrolysis, inflammatory, and fibrosis. Pyrosequencing of 16S rRNA genes revealed that the male mouse offspring with maternal normal calcium intake and the female mouse offspring with maternal low calcium intake, after the high-fat diet feeding, had distinct intestinal microbiota, which was closer to thosein mice with the normal diet feeding. Analysis of the functional features for the different microbiota was compatible with the expression of genes associated with lipogenesis, lipid oxidation and hydrolysis. Thus, there is a sex-specific manner for maternal calcium requirement to inhibit the progress of offspring NAFLD, that might be less for the female offspring and more for the male offspring.

Maternal dietary calcium status during pregnancy and lactation affects brain DHA accretion through modifying DNA methylation of fatty acid desaturases in the mouse offspring.

Disturbed calcium homeostasis has detrimental effects on brain development and function, particularly in early life because of epigenetic determination of early nutrition on later health. We hypothesized that the imbalance of calcium status in early life might have long-lasting effects on brain DHA accretion though epigenetic modification on fatty acid desaturases (Fads). Three to four week old C57BL/6J female mice were fed 3 reproductive diets with different calcium concentrations - low (LC, 0.25%), normal (NC, 0.70%) and high-calcium (HC, 1.20%) respectively throughout pregnancy and lactation. Maternal LC diet reduced tissue (brain and hepatic) DHA concentrations in both male and female offsprings at postnatal 21 day, with reductions in male instead of female offsprings in adulthood. Maternal HC diet only reduced hepatic DHA concentration in adult male offsprings. Furthermore, maternal LC diet reduced hepatic but increased brain expressions of Fads1 or Fads2 in 21-days old offsprings, with similar changes in adult male instead of female offsprings. Maternal HC diet reduced hepatic or brain expressions of Fads1 or Fads2 in 21-days old offsprings, and only reduced Fads2 in the liver with adult male offsprings. Determination of DNA methylation (CpG4, CpG5, CpG7,8, CpG14-17 and CpG19) showed that maternal LC diet caused hypermethylation of Fads2 promoter in the liver and hypomethylation in the brain in 21-days old offsprings, as well as in adult male offsprings. These data demonstrate that the imbalance of calcium intake in early life might have long-term gender-specific effects on brain accretion of DHA mediated by altered DNA methylation and associated expressions of Fads.

Genome-wide screen of promoter methylation identifies novel markers in diet-induced obese mice.

OBJECTIVE: To investigate the genome-wide promoter methylation and gene expression for the identification of methylation markers in obesity. METHODS: Using a high-fat, diet-induced obese mouse model, we performed comprehensive DNA methylation profiling of gene promoters to determine the differentially methylated genes using methylated DNA immunoprecipitation followed by hybridization to the NimbleGen MM8 CpG plus Promoter Microarray. We further integrated epigenomics data with gene expression profiling to identify promoters exhibiting an association between methylation status and the expression of downstream genes. RESULTS: A total of 24 hypermethylated promoters and 42 hypomethylated promoters in epididymal fat were selected as methylation markers, which were associated with downregulated and upregulated gene expression, respectively. The promoter methylation and differential gene expression of three markers (Mmp2, Foxj3 and Ube2q2) in the fat were validated by sequencing bisulfitemodified DNA and real-time reverse transcriptase PCR. The genes with these differentially methylated promoters and the associated transcriptional expression in the fat were primarily involved in biological activities in lipid metabolism and storage, cellular differentiation, immunity and the pathogenesis of obesity-related complications. CONCLUSIONS: This study represents the first effort to determine methylation markers in obese mice that may regulate gene transcription in obesity. Our approach has potential relevance for clinical applications by identifying markers useful in elucidating the mechanisms of obesity pathogenesis and its complications.

OBJETIVO: Investigar la metilación pangenómica del promotor y la expresión génica para la identificación de los marcadores de metilación en la obesidad. MÉTODOS: Empleando un modelo de ratón con obesidad inducida por la dieta con alto contenido en grasa, realizamos un perfil exhaustivo de la metilación del ADN de los genes promotores para determinar los genes metilados diferencialmente utilizando la inmunoprecipitación del ADN metilado seguida de la hibridación del NimbleGen MM8 CpG y el Promoter Microarray. Posteriormente, integramos los datos de la epigenómica con el perfil de expresión génica para identificar los promotores que mostraban una asociación entre el estado de metilación y la expresión de los genes sucesivos. RESULTADOS: Se seleccionó un total de 24 promotores hipermetilados y 42 promotores hipometilados en la grasa epididimaria como marcadores de la metilación, que se asociaron con la expresión génica regulada al alza y a la baja, respectivamente. La metilación del promotor y la expresión génica diferencial de tres marcadores (Mmp2, Foxj3 y Ube2q2) de la grasa se validaron mediante secuenciación del ADN modificado por bisulfito y por PCR de la transcriptasa reversa en tiempo real. Los genes con estos promotores metilados de forma diferencial y la expresión transcripcional asociada en la grasa estaban implicados primariamente en las actividades biológicas del metabolismo y almacenamiento de los lípidos, la diferenciación celular, la inmunidad y la patogenia de las complicaciones relacionadas con la obesidad. CONCLUSIONES: Este estudio representa el primer intento por determinar los marcadores de la metilación en los ratones obesos que pueden regular la transcripción génica en la obesidad. Nuestro abordaje tiene una relevancia potencial por sus aplicaciones clínicas al identificar marcadores útiles en la dilucidación de los mecanismos de la patogenia de la obesidad y sus complicaciones.