Bifocal photon sieve imaging in the hard x-ray region.

Hard x-rays are widely used for plasma diagnosis, nondestructive inspection, and high-resolution x-ray imaging. A typical x-ray source is a tabletop micro-focus x-ray source. Here, a bifocal photon sieve (PS) with the smallest diameter of 59.6 nm was designed and fabricated by electron-beam lithography to focus hard x-rays on variable-resolution array images. An imaging experiment at 8.39 keV demonstrates that the designed and fabricated PS has two different focal lengths. The numerous pinholes that can be optimized provide richer degrees of freedom to realize considerably more functionalities. A multi-focal PS provides the possibility of splitting x-rays and further extends interferometry from visible light to hard x-rays.

Reduction of Backward Scatterings at the Low-Coherence Kunwu Laser Facility.

We report the first experimental observation on the reduction of backward scatterings by an instantaneous broadband laser with 0.6% bandwidth in conditions of interest for inertial confinement fusion at the low-coherence Kunwu laser facility. The backscatter of stimulated Brillouin scattering (SBS) was robustly reduced by half at intensities of 1-5×10^{14} W/cm^{2} with the 0.53-µm broadband laser in comparison with the monochromatic laser. As SBS dominates energy loss of laser-plasma interactions, the reduction of that demonstrates the enhancement of laser-target coupling by the use of broadband laser. The mitigation of filamentation leads to the reduction of stimulated Raman backscattering at low intensities. In addition, the three-halves harmonic emission was reduced with the broadband laser as well.

Mitigation of electromagnetic pulses interfering with Thomson parabola ion spectrometers at XG-III laser facility.

The Thomson parabola ion spectrometer is vulnerable to intense electromagnetic pulses (EMPs) generated by a high-power laser interacting with solid targets. A metal shielding cage with a circular aperture of 1 mm diameter is designed to mitigate EMPs induced by a picosecond laser irradiating a copper target in an experiment where additionally an 8-ns delayed nanosecond laser is incident into an aluminum target at the XG-III laser facility. The implementation of the shielding cage reduces the maximum EMP amplitude inside the cage to 5.2 kV/m, and the simulation results indicate that the cage effectively shields electromagnetic waves. However, the laser-accelerated relativistic electrons which escaped the target potential accumulate charge on the surface of the cage, which is responsible for the detected EMPs within the cage. To further alleviate EMPs, a lead wall and an absorbing material (ECCOSORB AN-94) were added before the cage, significantly blocking the propagation of electrons. These findings provide valuable insights into EMP generation in large-scale laser infrastructures and serve as a foundation for electromagnetic shielding design.

The generation of a fourth-harmonic probe and its application in Nomarski interferometry at Shengguang-II.

In this work, a design for the generation of a 4ω (263-nm) probe converted from a 1ω (1053-nm) laser is presented. The design is based on a beta-barium borate and potassium dihydrogen phosphate two-step frequency-conversion process. A suitable configuration for Nomarski interferometry based on the 4ω probe is proposed, for measuring the electron density of laser-produced plasmas. The signal-to-noise ratio of the output 4ω probe to 1ω and 2ω light after frequency quadrupling and harmonic separation is 103 with a 0.5 GW/cm2 1ω input but decreases to ∼102 at intensities below 0.1 GW/cm2. Additional noise suppression by a factor of 104 is achieved using filters before the interferometer recording camera. The spatial resolution of the diagnostic can reach 5.2 µm for a 10% modulation transfer function. An experiment validating the probe diagnostic system is conducted at the Shengguang-II laser facility. A clear interferogram of an aluminum plasma is obtained with 0.1 GW/cm2 input, suggesting a maximal electron density of about 2.5 × 1020 cm-3 as retrieved through an inverse-Abel transform. The design proposed in this paper is appropriate for a small laser device or a large laser facility that lacks a separate diagnostic beam, and it is an inexpensive solution as it requires small-aperture 1ω input at a relatively low intensity. All the key parameters necessary to implement the design are provided in detail, making it straightforward to reproduce or transplant the system for specific uses.

A laser wakefield acceleration facility using SG-II petawatt laser system.

Laser wakefield acceleration (LWFA) using PW-class laser pulses generally requires cm-scale laser-plasma interaction Rayleigh length, which can be realized by focusing such pulses inside a long underdense plasma with a large f-number focusing optic. Here, we present a new PW-based LWFA instrument at the SG-II 5 PW laser facility, which employs f/23 focusing. The setup also adapted an online probing of the plasma density via Nomarski interferometry using a probe laser beam having 30 fs pulse duration. By focusing 1-PW, 30-fs laser pulses down to a focal spot of 230 µm, the peak laser intensity reached a mild-relativistic level of 2.6 × 1018 W/cm2, a level modest for standard LWFA experiments. Despite the large aspect ratio of >25:1 (transverse to longitudinal dimensions) of the laser pulse, electron beams were observed in our experiment only when the laser pulse experienced relativistic self-focusing at high gas-pressure thresholds, corresponding to plasma densities higher than 3 × 1018 cm-3.

Glucose-6-Phosphate Dehydrogenase, Redox Homeostasis and Embryogenesis.

Normal embryogenesis requires complex regulation and precision, which depends on multiple mechanistic details. Defective embryogenesis can occur by various mechanisms. Maintaining redox homeostasis is of importance during embryogenesis. NADPH, as produced from the action of glucose-6-phosphate dehydrogenase (G6PD), has an important role in redox homeostasis, serving as a cofactor for glutathione reductase in the recycling of glutathione from oxidized glutathione and for NADPH oxidases and nitric oxide synthases in the generation of reactive oxygen (ROS) and nitrogen species (RNS). Oxidative stress differentially influences cell fate and embryogenesis. While low levels of stress (eustress) by ROS and RNS promote cell growth and differentiation, supra-physiological concentrations of ROS and RNS can lead to cell demise and embryonic lethality. G6PD-deficient cells and organisms have been used as models in embryogenesis for determining the role of redox signaling in regulating cell proliferation, differentiation and migration. Embryogenesis is also modulated by anti-oxidant enzymes, transcription factors, microRNAs, growth factors and signaling pathways, which are dependent on redox regulation. Crosstalk among transcription factors, microRNAs and redox signaling is essential for embryogenesis.

Radial-shearing interferometric imaging with Theon-Kepler bifocal telescope.

A method of radial-shearing interferometric imaging based on the Theon-Kepler bifocal telescope is proposed. The Theon-Kepler bifocal telescope system consists of two identical Theon photon sieves with bifocal spots. The short focal length of the first photon sieve coincides with the long focal length of the second photon sieve. At the same time, the first focal length coincides with the second short focal length. This setup naturally constitutes two sets of 4f systems. When a plane wave is incident on the bifocal telescope, two plane waves of different sizes are emitted. These two beams undergo radial-shearing interference. The common-path setup of this new type of radial-shearing interferometer is simple, with low requirements for the experimental environment and strong anti-interference ability.

Plasma modulator for high-power intense lasers.

A type of plasma-based optical modulator is proposed for the generation of broadband high-power laser pulses. Compared with normal optical components, plasma-based optical components can sustain much higher laser intensities. Here we illustrate via theory and simulation that a high-power sub-relativistic laser pulse can be self-modulated to a broad bandwidth over 100% after it passes through a tenuous plasma. In this scheme, the self-modulation of the incident picoseconds sub-relativistic pulse is realized via stimulated Raman forward rescattering in the quasi-linear regime, where the stimulated Raman backscattering is heavily dampened. The optimal laser and plasma parameters for this self-modulation have been identified. For a laser with asub-relativistic intensity of I ∼ 1017W/cm2, the time scale for the development of self-modulation is around 103 light periods when stimulated Raman forward scattering has been fully developed. Consequently, the spatial scale required for such a self-modulation is in the order of millimeters. For a tenuous plasma, the energy conversion efficiency of this self-modulation is around 90%. Theoretical predictions are verified by both one-dimensional and two-dimensional particle-in-cell simulations.

Temporal contrast enhancement of ultrashort pulses using a spatiotemporal plasma-lens filter.

The spatiotemporal plasma-lens filter proposed here enhances the temporal contrast of the ultrashort pulse laser by combining plasma optics and spatial filtering. Experimentally, the spatiotemporal plasma-lens filter has improved the temporal contrast by 2 orders of magnitude with 80% laser transmission efficiency under a 1 Hz repetitive laser operation. Not only were the pre-pulse and the pedestal cleaned out, but also the rising edge of the main pulse was sharpened.

MicroRNA-937 is overexpressed and predicts poor prognosis in patients with colon cancer.

BACKGROUND: Colon cancer is a heterogeneous tumor and a leading cause of cancer-related mortality. MicroRNA (miRNA) has been proposed as the biomarker in cancers. The aim of this study was to investigate the clinical significance and potential functional role of miR-937 in colon cancer. METHODS: In the present study, reverse transcription-quantitative polymerase chain reaction (qRT-PCR) was conducted to examine the expression levels of miR-937 in colon cancer tissues and cell lines. Kaplan-Meier curve and Cox regression analyses were used to determine the prognostic impact of miR-937 on survival. Cell Counting Kit-8 and Transwell assays were performed to examine cell proliferation, migration, and invasion, respectively. RESULTS: miR-937 was significantly upregulated in colon cancer tissues and cell lines. Clinical analysis results showed that miR-937 expression was associated with lymph node metastasis and TNM stage. Patients with high miR-937 expression predicted a shorter overall survival rate. Functionally, overexpression of miR-937 promoted cell proliferation, migration, and invasion, while inhibition of miR-937 inhibited these cellular behaviors in vitro. CONCLUSIONS: These results suggested that miR-937 may act as a prognostic biomarker and a potential target for therapeutic strategy, as well as promote proliferation, migration, and invasion of colon cancer.

The Redox Role of G6PD in Cell Growth, Cell Death, and Cancer.

The generation of reducing equivalent NADPH via glucose-6-phosphate dehydrogenase (G6PD) is critical for the maintenance of redox homeostasis and reductive biosynthesis in cells. NADPH also plays key roles in cellular processes mediated by redox signaling. Insufficient G6PD activity predisposes cells to growth retardation and demise. Severely lacking G6PD impairs embryonic development and delays organismal growth. Altered G6PD activity is associated with pathophysiology, such as autophagy, insulin resistance, infection, inflammation, as well as diabetes and hypertension. Aberrant activation of G6PD leads to enhanced cell proliferation and adaptation in many types of cancers. The present review aims to update the existing knowledge concerning G6PD and emphasizes how G6PD modulates redox signaling and affects cell survival and demise, particularly in diseases such as cancer. Exploiting G6PD as a potential drug target against cancer is also discussed.

Clinical manifestations and endoscopic presentations of gastric lymphoma: a multicenter seven year retrospective survey

Background and aim: To improve the diagnostic rate of gastric lymphoma by analyzing clinical and endoscopic features of patients with gastric lymphoma and suspected gastric lymphoma. Methods: Clinical and endoscopic records of 35 patients with gastric lymphoma (positive group) and 133 patients with suspected gastric lymphoma but subsequent non-malignant pathology (negative group) were analyzed retrospectively. Data from another 99 gastric lymphoma patients with malignant pathology but nonspecific endoscopy (endoscopy non-suspect group) were analyzed. Results: Abdominal pain was the predominant symptom reported in both the positive and negative lymphoma groups, representing 60.0 and 52.5%, respectively. No significant differences in age, sex and clinical manifestations in subjects from the two groups were found. In the positive group, 54.3% were ulcerative; 34.3%, infiltrative; 8.5%, polypoid; and 2.9%, granulonodular. In the negative group, 52.6% were infiltrative; 42.1%, ulcerative; 4.5%, granulonodular; and 0.75%, polypoid. The endoscopic results varied between the two groups (p < 0.05). In the non-suspect group, 66.7% were ulcerative; 17.2%, infiltrative; 14.1%, polypoid; and 2.0%, granulonodular. With regards to histology, diffuse large B cell lymphoma was the most common subtype. The sensitivity of endoscopy was 60% for detecting malignancy and 21% for gastric lymphoma. Conclusion: The present study suggests that gastric lymphoma and suspected gastric lymphoma have similar clinical features. Gastric lymphoma presented mainly as macroscopic ulcerative lesions, whereas suspected gastric lymphoma appeared mainly as infiltrative lesions. Although the diagnostic rate of gastric lymphoma was relatively low (21%), it can be identified by endoscopy (60%). To improve diagnosis, repetitive endoscopic biopsies should be performed and novel endoscopic techniques developed in the future (AU)

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Clinical manifestations and endoscopic presentations of gastric lymphoma: a multicenter seven year retrospective survey.

BACKGROUND AND AIM: To improve the diagnostic rate of gastric lymphoma by analyzing clinical and endoscopic features of patients with gastric lymphoma and suspected gastric lymphoma. METHODS: Clinical and endoscopic records of 35 patients with gastric lymphoma (positive group) and 133 patients with suspected gastric lymphoma but subsequent non-malignant pathology (negative group) were analyzed retrospectively. Data from another 99 gastric lymphoma patients with malignant pathology but nonspecific endoscopy (endoscopy non-suspect group) were analyzed. RESULTS: Abdominal pain was the predominant symptom reported in both the positive and negative lymphoma groups, representing 60.0 and 52.5%, respectively. No significant differences in age, sex and clinical manifestations in subjects from the two groups were found. In the positive group, 54.3% were ulcerative; 34.3%, infiltrative; 8.5%, polypoid; and 2.9%, granulonodular. In the negative group, 52.6% were infiltrative; 42.1%, ulcerative; 4.5%, granulonodular; and 0.75%, polypoid. The endoscopic results varied between the two groups (p < 0.05). In the non-suspect group, 66.7% were ulcerative; 17.2%, infiltrative; 14.1%, polypoid; and 2.0%, granulonodular. With regards to histology, diffuse large B cell lymphoma was the most common subtype. The sensitivity of endoscopy was 60% for detecting malignancy and 21% for gastric lymphoma. CONCLUSION: The present study suggests that gastric lymphoma and suspected gastric lymphoma have similar clinical features. Gastric lymphoma presented mainly as macroscopic ulcerative lesions, whereas suspected gastric lymphoma appeared mainly as infiltrative lesions. Although the diagnostic rate of gastric lymphoma was relatively low (21%), it can be identified by endoscopy (60%). To improve diagnosis, repetitive endoscopic biopsies should be performed and novel endoscopic techniques developed in the future.

Design and calibration of hot-electron spectrometer array for angle-resolved measurement.

A hot-electron spectrometer array with two-dimensional distribution has been designed with a wide-angle range and high-energy resolution to measure the spatially resolved electron spectra for high-power-laser plasma interaction experiments. It consisted of 19 identical electron spectrometers set in three directions with an interval of 10°. Each electron spectrometer was designed with a uniform magnetic field to detect electrons in the range from 20 to 500 keV. The spectrometers were calibrated using electrons from an accelerator. In an experiment, the spatially resolved electron energy spectra, which approximately had a Maxwell distribution, were obtained from an aluminum foil target irradiated by a 0.53-µm laser pulse.

What has passed is prolog: new cellular and physiological roles of G6PD.

G6PD deficiency has been the most pervasive inherited disorder in the world since having been discovered. G6PD has an antioxidant role by functioning as a major nicotinamide adenine dinucleotide phosphate (NADPH) provider to reduce excessive oxidative stress. NADPH can produce reactive oxygen species (ROS) and reactive nitrogen species (RNS) mediated by NADPH oxidase (NOX) and nitric oxide synthase (NOS), respectively. Hence, G6PD also has a pro-oxidant role. Research in the past has focused on the enhanced susceptibility of G6PD-deficient cells or individuals to oxidative challenge. The cytoregulatory role of G6PD has largely been overlooked. By using a metabolomic approach, it is noted that upon oxidant challenge, G6PD-deficient cells will reprogram the GSH metabolism from regeneration to synthesis with exhaustive energy consumption. Recently, new cellular/physiologic roles of G6PD have been discovered. By using a proteomic approach, it has been found that G6PD plays a regulatory role in xenobiotic metabolism possibly via NOX and the redox-sensitive Nrf2-signaling pathway to modulate the expression of xenobiotic-metabolizing enzymes. Since G6PD is a key regulator responsible for intracellular redox homeostasis, G6PD deficiency can alter redox balance leading to many abnormal cellular effects such as the cellular inflammatory and immune response against viral infection. G6PD may play an important role in embryogenesis as G6PD-knockdown mouse cannot produce offspring and G6PD-deficient C. elegans with defective egg production and hatching. This array of findings indicates that the cellular and physiologic roles of G6PD, other than the classical role as an antioxidant enzyme, deserve further attention.

Glucose 6-phosphate dehydrogenase knockdown enhances IL-8 expression in HepG2 cells via oxidative stress and NF-κB signaling pathway.

BACKGROUND: This study was designed to investigate the effect of glucose 6-phosphate dehydrogenase (G6PD) deficiency on pro-inflammatory cytokine secretion using a palmitate-induced inflammation HepG2 in vitro model. The modulation of cellular pro-inflammatory cytokine expression under G6PD deficiency during chronic hepatic inflammation has never been investigated before. METHODS: The culture medium of untreated and palmitate-treated G6PD-scramble (Sc) and G6PD-knockdown (Gi) HepG2 cells were subjected to cytokine array analysis, followed by validation with ELISA and qRT-PCR of the target cytokine. The mechanism of altered cytokine secretion in palmitate-treated Sc and Gi HepG2 cells was examined in the presence of anti-oxidative enzyme (glutathione peroxidase, GPX), anti-inflammatory agent (curcumin), NF-κB inhibitor (BAY11-7085) and specific SiRNA against NF-κB subunit p65. RESULTS: Cytokine array analysis indicated that IL-8 is most significantly increased in G6PD-knockdown HepG2 cells. The up-regulation of IL-8 caused by G6PD deficiency in HepG2 cells was confirmed in other G6PD-deficient cells by qRT-PCR. The partial reduction of G6PD deficiency-derived IL-8 due to GPX and NF-κB blockers indicated that G6PD deficiency up-regulates pro-inflammatory cytokine IL-8 through oxidative stress and NF-κB pathway. CONCLUSIONS: G6PD deficiency predisposes cells to enhanced production of pro-inflammatory cytokine IL-8. Mechanistically, G6PD deficiency up-regulates IL-8 through oxidative stress and NF-κB pathway. The palmitate-induced inflammation in G6PD-deficient HepG2 cells could serve as an in vitro model to study the role of altered redox homeostasis in chronic hepatic inflammation.

Analysis of the causes and clinical characteristics of jejunoileal hemorrhage in China: a multicenter 10 year retrospective survey.

BACKGROUND: A retrospective study was performed to assess the causes, diagnostic methods for, and clinical features of, jejunoileal hemorrhage in Shandong province, China and to derive recommendations for management of this condition from these data. METHODS: We performed a retrospective systematic collection of data from between January 1999 and December 2008 in seven cities in Shandong province, China, identified 72 patients with jejunoileal hemorrhage and analyzed the relevant clinical data. RESULTS: Overall, tumors were the most common cause of jejunoileal hemorrhage (42 patients, 58.3%). The causes of this condition were significantly different (P < 0.05) in male and female patients. In male patients, the commonest factors were tumor (52.2%), enteritis (17.4%) and angiopathy (15.2%). However, in female patients, tumors accounted for a greater proportion of cases (18/26, 69.2%). In 38 cases (52.8%) the diagnosis was made by intraoperative enteroscopy or laparotomy, in 14 by capsule endoscopy and in the remainder by radiological methods. The most frequent presentation was melena (62.7%), followed by maroon stools (26.9%) and hematochezia (9.0%). Of the 72 patients,laparotomy is the main treatment method. CONCLUSION: Tumor, enteritis and angiopathy and diverticular disease are the most common causes of jejunoileal hemorrhage in Shandong province, China. The main clinical manifestations are bloody stools, most commonly in the form of melena, with or without abdominal pain. We recommend that female patients over the age of 40 with jejunoileal hemorrhage accompanied by abdominal pain should undergo urgent further assessment because of the strong probability of jejunoileal tumor.

Correlations between serum levels of vascular endothelial growth factor and endostatin with clinical pathological characteristics of patients with gastrointestinal cancers.

BACKGROUND/AIMS: To study the relationship between serum levels of vascular endothelial growth factor (VEGF), endostatin and pathological characteristics of patients with gastrointestinal cancers. METHODOLOGY: Serum VEGF and endostatin levels were measured by enzyme-linked immunoassay in 60 patients with gastric carcinoma, 55 with hepatocellular carcinoma and 58 with colorectal carcinoma before and after surgical resection. RESULTS: The preoperative levels of VEGF and endostatin in patients with gastrointestinal cancers were significantly higher than those in control groups respectively. They were closely related to the grades of cell differentiation, size of primary tumors, depth of invasion, metastasis and pathological stage, but not to tumor site and gender. The postoperative VEGF levels were significantly lower than those of preoperation, while postoperative endostatin levels were significantly higher than those of preoperation. CONCLUSIONS: Preoperative serum VEGF and endostatin levels may be used for evaluating the biological behavior, invasion and metastasis of gastric, hepatocellular and colorectal carcinoma. Elevated serum endostatin levels were found in the patients with gastric cancer, HCC and colorectal cancer after surgery. Gastrointestinal tumor itself may be not the main source of endostatin.