ABSTRACT
The low (sub %) efficiencies so-far demonstrated for nonlinear optical down-conversion to terahertz (THz) frequencies are a primary limiting factor in the generation of high-energy, high-field THz-radiation pulses (in particular narrowband, multicycle pulses) needed for many scientific fields. However, simulations predict that far higher conversion efficiencies are possible by use of suitably-optimized optical sources. Here we implement a customized optical laser system producing highly-tunable trains of infrared pulses and systematically explore the experimental optimization of the down-conversion process. Our setup, which allows tuning of the energy, duration, number and periodicity of the pulses in the train, provides a unique capability to test predictions of analytic theory and simulation on the parameter dependences for the optical-to-THz difference-frequency generation process as well as to map out, with unprecedented precision, key properties of the nonlinear crystal medium. We discuss the agreements and deviations between simulation and experimental results which, on the one hand, shed light on limitations of the existing theory, and on the other hand, provide the first steps in a recipe for development of practical, high-field, efficiency-optimized THz sources.
ABSTRACT
Ghrelin is a gut hormone shown to have protective effects throughout the gastrointestinal tract. This study aims to investigate its protective effect in celiac disease induced in rats. Twenty-four rat pups were divided into 4 groups as follows: control, disease (1.5 mg/g intragastric gliadin), co-treatment (50 ng/g intraperitoneal ghrelin after gliadin gavage) and pretreatment (50 ng/g intraperitoneal ghrelin before gliadin gavage). Animals' weight gain was charted. Histological features assessed include villus length, villus width, crypt depth and number of intraepithelial lymphocytes. Tissue interferon-gamma was quantified by ELISA. ANOVA was used to compare results statistically. Results showed that villi were shortened in the diseased group, but were as long as the control in pretreatment and co-treatment groups. Crypt depth had increased in disease group, but turned to normal in co-treatment group. Number of intraepithelial lymphocytes was significantly higher in disease group than the control, while no difference was observed between co-treatment and control groups. Disease and control animals weighed equally at the end of the experiment, but ghrelin-treated animals had significantly gained more weight than these two. Interferon-gamma measurement revealed no significant difference among groups. We concluded administration of ghrelin led to histological improvement of celiac disease which was more obvious if administered after exposure to gliadin.
Subject(s)
Celiac Disease/prevention & control , Ghrelin/pharmacology , Jejunum/drug effects , Animals , Celiac Disease/chemically induced , Celiac Disease/metabolism , Celiac Disease/pathology , Cytoprotection , Disease Models, Animal , Gliadin , Interferon-gamma/metabolism , Intestinal Mucosa/drug effects , Intestinal Mucosa/metabolism , Intestinal Mucosa/pathology , Jejunum/metabolism , Jejunum/pathology , Rats, Wistar , Time Factors , Weight GainABSTRACT
This study aimed to compare the in vitro effects of coculture with Sertoli and SIM mouse embryo-derived thioguanine- and ouabain-resistant (STO) feeder layer cells on the efficiency of adult mouse spermatogonial stem cells (SSCs) colony formation. Sertoli and SSCs were isolated from testes, and their identity was confirmed using immunocytochemistry against Oct4, CDH1, PLZF and C-kit for SSCs and vimentin for Sertoli cells. SSCs were cultured in a simple culture system (control group) and on top of the Sertoli and STO feeder layers for 2 weeks. The number and diameter of colonies were evaluated during third, 7th, 10th and 14th day of culture, and the expression of the Oct-4, α6 and ß1 integrins was assessed using quantitative RT-PCR. Significant differences were observed between the three groups, separately for each time (P < 0.05), with higher mean in number and diameter for Sertoli cells (P < 0.05). The results of RT-PCR showed higher gene expression of ß1 integrin in Sertoli group, but no significant differences were observed in Oct-4 and α6 integrin gene expression among the three groups. Based the on the optimal effect of Seroli cells on the colony formation of SSCs, it is suggested to use these cells for better colonisation of SSCs.
