Gastric cancer: epidemiology, biology, and prevention: a mini review

Gastric cancer is one of the most common causes of cancer-related mortality worldwide. The objective of this article is to review the epidemiology and biology of gastric cancer risk. This literature review explores the biological, clinical, and environmental factors that influence the rates of this disease and discuss the different intervention methods that may not only increase the awareness of gastric cancer but also increase screening in efforts to reduce the risk of gastric cancer. Helicobacter pylori infection is the primary risk factor for gastric cancer. Additional risk factors include geographical location, age, sex, smoking, socioeconomic status, dietary intake, and genetics. Primary and secondary prevention strategies such as dietary modifications and screenings are important measures for reducing the risk of gastric cancer. Interventions, such as H. pylori eradication through chemoprevention trials, have shown some potential as a preventative strategy. Although knowledge about gastric cancer risk has greatly increased, future research is warranted on the differentiation of gastric cancer epidemiology by subsite and exploring the interactions between H. pylori infection, genetics, and environmental factors. Better understanding of these relationships can help researchers determine the most effective intervention strategies for reducing the risk of this disease.

Very low loss reactively ion etched Tellurium Dioxide planar rib waveguides for linear and non-linear optics

We report on the fabrication and optical properties of the first very low loss nonlinear Tellurite planar rib waveguides ever demonstrated. A new reactive ion etch process based on Hydrogen as the active species was developed to accomplish the low propagation losses. Optical losses below approximately 0.05 dB/cm in most of the NIR spectrum and approximately 0.10 dB/cm at 1550 nm have been achieved - the lowest ever reported by more than an order of magnitude and clearly suitable for planar integrated devices. We demonstrate strong spectral broadening of 0.6 ps pulses in waveguides fabricated from pure TeO(2), in good agreement with simulations.

Optimisation of cascaded Yb fiber amplifier chains using numerical-modelling

We show that it is possible to adapt existing software packages developed originally for modeling telecommunication devices and systems to reliably predict and optimize the performance of high-power Ytterbium-doped fiber amplifier and laser systems. The ready availability of a flexible, user-friendly design tool should be of considerable practical interest to scientists and engineers working with this important new laser technology since Ytterbium amplifier and amplifier cascades are often difficult to optimize experimentally due to the three-level nature of the Ytterbium laser transition. As examples of the utility and accuracy of the software, as well as the complexity of the systems and amplifier properties that can be successfully modeled, we present a comparison of experimental and theoretical results for individual core and cladding pumped amplifiers, and also for an ultra-short pulse four-stage amplifier system optimized both to provide a broad gain bandwidth and to minimize nonlinear effects. We also show how high energy 100 ns pulses with complex user definable temporal profiles can be created in a gain-saturated amplifier by suitable pre-shaping of the low-energy input pulses. Furthermore, with appropriate modifications the same software package can be applied to fiber amplifiers based on other rare-earth elements and glass hosts.

Adaptive pulse shape control in a diode-seeded nanosecond fiber MOPA system

We demonstrate active shaping of the driving electrical pulses to a laser diode in order to compensate for the pulse shaping effects of gain saturation in an Yb doped fiber amplifier cascade and to allow the generation of user defined customized output pulse shapes. In particular we demonstrate the generation of square output pulses, which have the potential to significantly increase the maximum pulse energy extractable from an amplifier before the peak power reaches the threshold for SRS, and for high efficiency frequency conversion.

Giant cell formation in cells exposed to 740 nm and 760 nm optical traps

BACKGROUND AND OBJECTIVE

Optical trapping is becoming a useful and widespread technique for the micromanipulation of cells and organelles. Giant cell formation following optical trapping was studied to detect the potential adverse effects.

STUDY DESIGN/MATERIALS AND METHODS

The nuclei of preselected single CHO cells were exposed to 740 nm and 760 nm laser microbeam generated by a titanium-sapphire tunable laser at 88 and 176 mW and different time exposures. The irradiated single cells were recorded and observed morphologically following exposure. Giant cells were tabulated and photographed.

RESULTS

The irradiated cells either failed to divide, or they underwent nuclear proliferation to form giant cells through endoreduplication.

CONCLUSION

Giant cells were induced by both 740 nm and 760 nm. The frequency of giant cell formation was higher for the longer time exposures and at the higher power densities. The use of an optical etalon to remove intracavity mode beating and high peak powers of the titanium-sapphire laser caused a significant reduction in the formation of giant cells.

Wavelength dependence of cell cloning efficiency after optical trapping

A study on clonal growth in Chinese hamster ovary (CHO) cells was conducted after exposure to optical trapping wavelengths using Nd:YAG (1064 nm) and tunable titanium-sapphire (700-990 nm) laser microbeam optical traps. The nuclei of cells were exposed to optical trapping forces at various wavelengths, power densities, and durations of exposure. Clonal growth generally decreased as the power density and the duration of laser exposure increased. A wavelength dependence of clonal growth was observed, with maximum clonability at 950-990 nm and least clonability at 740-760 nm and 900 nm. Moreover, the most commonly used trapping wavelength, 1064 nm from the Nd:YAG laser, strongly reduced clonability, depending upon the power density and exposure time. The present study demonstrates that a variety of optical parameters must be considered when applying optical traps to the study of biological problems, especially when survival and viability are important factors. The ability of the optical trap to alter either the structure or biochemistry of the process being probed with the trapping beam must be seriously considered when interpreting experimental results.