Engineering Refractive Index Contrast in Thin Film Barium Titanate-on-Insulator.

Barium titanate-on-insulator has demonstrated excellent vertical optical confinement, low loss, and strong electro-optic properties. To fabricate a waveguide-based device, a region of higher refractive index must be created to confine a propagating mode, one way of which is through dry etching to form a ridge. However, despite recent progress achieved in etching barium titanate and similar materials, the sidewall and surface roughness resulting from the physical etching typically used limit the achievable ridge depth. This motivates the exploration of etch-free methods to achieve the required index contrast. Here, we introduce three etch-free methods to create a refractive index contrast in barium titanate-on-insulator, including a metal diffusion method, proton beam irradiation method, and crystallinity control method. Notably, molybdenum-diffused barium titanate leads to a large index change of up to 0.17. The methods provided in this work can be further developed to fabricate various on-chip barium titanate optical waveguide-based devices.

Cell-type heterogeneity: Why we should adjust for it in epigenome and biomarker studies.

Most studies aiming to identify epigenetic biomarkers do so from complex tissues that are composed of many different cell-types. By definition, these cell-types vary substantially in terms of their epigenetic profiles. This cell-type specific variation among healthy cells is completely independent of the variation associated with disease, yet it dominates the epigenetic variability landscape. While cell-type composition of tissues can change in disease and this may provide accurate and reproducible biomarkers, not adjusting for the underlying cell-type heterogeneity may seriously limit the sensitivity and precision to detect disease-relevant biomarkers or hamper our understanding of such biomarkers. Given that computational and experimental tools for tackling cell-type heterogeneity are available, we here stress that future epigenetic biomarker studies should aim to provide estimates of underlying cell-type fractions for all samples in the study, and to identify biomarkers before and after adjustment for cell-type heterogeneity, in order to obtain a more complete and unbiased picture of the biomarker-landscape. This is critical, not only to improve reproducibility and for the eventual clinical application of such biomarkers, but importantly, to also improve our molecular understanding of disease itself.

Autonomous absolute calibration of an ICCD camera in single-photon detection regime.

Intensified charge coupled device (ICCD) cameras are widely used in vari-ous applications such as microscopy, astronomy, spectroscopy. Often they are used as single-photon detectors, with thresholding being an essential part of the readout. In this paper, we measure the quantum efficiency of an ICCD camera in the single-photon de-tection mode using the Klyshko absolute calibration technique. The quantum efficiency is obtained as a function of the threshold value and of the wavelength of the detected light. In addition, we study the homogeneity of the photon sensitivity over the camera chip area. The experiment is performed in the autonomous regime, without using any additional detectors. We therefore demonstrate the self-calibration of an ICCD camera.

Moyamoya disease with posterior communicating artery aneurysm: a case report.

In moyamoya disease (MMD), subsequent aneurysm in the proximal part of the posterior communicating artery (PcomA) is extremely rare. We report the case of a middle-aged female patient with MMD, who presented with a ruptured wide-necked aneurysm at the proximal part of the developed PcomA that converged with the posterior cerebral artery (PCA) and supplied the distal area. Endovascular treatment was performed, but the stent-assisted coil embolization resulted in occlusion of the internal carotid artery (ICA) above the ophthalmic artery and PcomA. Due to good compensatory collateral circulation, the patient was improved after surgery and had no complications. One-year followup DSA did not show recurrence of the aneurysm. The right ICA was still embolized, but with good compensatory collateral circulation. We conclude that, for an MMD patient with an aneurysm at the proximal part of the developed PcomA, if the ICA and PcomA are accidentally occluded, then the patient may still have a good prognosis due to sufficient collateral blood circulation.

Enhanced expressions and activations of leukotriene C4 synthesis enzymes in D-galactosamine/lipopolysaccharide-induced rat fulminant hepatic failure model.

AIM: To investigate the expression and activity of leukotriene C4 (LTC4) synthesis enzymes and their underlying relationship with cysteinyl leukotriene (cys-LT) generation in a rat fulminant hepatic failure (FHF) model induced by D-galactosamine/lipopolysaccharide (D-GalN/ LPS). METHODS: Rats were treated with D-GalN (300 mg/kg) plus LPS (0.1 mg/kg) for 1, 3, 6, and 12 h. Enzyme immunoassay was used to determine the hepatic cys-LT content. Reverse transcription-polymerase chain reaction (RT-PCR), Western blot or immunohistochemical assay were employed to assess the expression or location of LTC4 synthesis enzymes, which belong to membrane associated proteins in eicosanoid and glutathione (MAPEG) metabolism superfamily. Activity of LTC4 synthesis enzymes was evaluated by determination of the products of LTA4 after incubation with liver microsomes using high performance liquid chromatography (HPLC). RESULTS: Livers were injured after treatment with D-GalN/LPS, accompanied by cys-LT accumulation at the prophase of liver injury. Both LTC4 synthase (LTC4S) and microsomal glutathione-S-transferase (mGST) 2 were expressed in the rat liver, while the latter was specifically located in hepatocytes. Their mRNA and protein expressions were up-regulated at an earlier phase after treatment with D-GalN/LPS. Meantime, a higher activity of LTC4 synthesis enzymes was detected, although the activity of LTC4S played the main role in this case. CONCLUSION: The expression and activity of both LTC4S and mGST2 are up regulated in a rat FHF model, which are, at least, partly responsible for cys-LT hepatic accumulation.

[Gene expressions of LTC4 synthase homologs in Con A-induced mouse hepatitis and regulative effect of cyclosporine A].

OBJECTIVE: To explore the gene expressions of LTC4 synthase homologs in concanavalin A (Con A)-induced mouse hepatitis and regulation role of cyclosporine A (Cs A) treatment. METHODS: Male Balb/c mouse liver injury model was developed by iv injection of Con A (20 mg/kg) and protected by Cs A pretreatment (150 mg/kg) before Con A administration. Blood samples were collected at indicated times after Con A treatment with or without Cs A pretreatment. Liver damage was assessed by serum transaminase ALT and AST measurement and histological evaluation. Meantime, three LTC4 synthase homolog gene expressions were determined by RT-PCR. RESULTS: Serum ALT and AST upregulation were accompanied with histological damage at 2 h after Con A administration, and further aggravated at 8 h. mGST2 gene expression increased 1.7 fold at 2 h and 1.9 fold at 8 h, while the expression of LTC4 S and mGST3 changed little. Pretreatment with Cs A prevented mouse liver from injury by Con A and partly inhibited the mGST2 gene expression upregulation. CONCLUSIONS: Administration of Con A in mouse lead to a significant increase of mGST2 gene expression without any significant effect on LTC4 S and mGST3 mRNA levels. Cs A pretreatment results in protection of liver damage, whereas fails to fully inhibit the increase of mGST2 gene expression.

[Protective effects of triterpenoids on primarily cultured rat hepatocytes injured by D-galactosamine and carbon tetrachloride].

OBJECTIVE: To investigate the protective effects and mechanism of triterpenoids on primarily cultured rat hepatocytes injured by D-galactosamine (D-GalN) or carbon tetrachloride (CCl4). METHODS: Rat hepatocytes were isolated by two-step collagenase perfusion and cultured in RPMI 1640 medium. Protective effects of asiatic acid (AA) and beta-glycyrrhetinic acid (GA) were evaluated on hepatocytes injured by D-GalN (2 mmol/L) or CCl4 (10 mmol/L). Cell morphology was observed by light microscope, cell viability was measured by MTT assay, AST and LDH were determined by an automatic analyzer. Fluorescence assay was applied to test reactive oxygen species (ROS), nitric oxide end products (NOx) and reduced glutathione (GSH), and JC-1 staining was used to determine mitochondria membrane potential (DeltaPsim). RESULTS: AST and LDH in medium were decreased when treated with AA and GA after D-GalN injury (P<0.05), furthermore AA enhanced the hepatocyte viability (P<0.05). Moreover, AA and GA significantly reduced ROS and NOx generation, and ameliorated DeltaPsim lost induced by D-GalN. AA also inhibited GSH decrease due to D-GalN and CCl4 treatment. CONCLUSION: Both AA and GA could protect hepatocytes from D-GalN and CCl4 injuries, which is associated with reducing intracellular ROS and NOx, reversing GSH depression and ameliorating DeltaPsim lost.