Monthly Tip Sheet Research Highlights from Biomedical Optics Express - September 2011


FOR IMMEDIATE RELEASE

Media contact:
Angela Stark
The Optical Society
202.416.1443
astark@osa.org

Monthly Tip Sheet: Research Highlights from Biomedical Optics Express - September 2011

WASHINGTON, Sept. 13—The following highlights summarize key research published in the September issue of Biomedical Optics Express, the Optical Society’s (OSA) principal outlet for serving the biomedical optics community with rapid, open-access, peer-reviewed papers related to optics, photonics and imaging in the life sciences. The journal scope encompasses theoretical modeling and simulations, technology development, and biomedical studies and clinical applications.

In this issue:

  1. New hybrid imaging device shows promise in spotting hard-to-detect ovarian cancer
  2. Using lasers to vaporize tissue at multiple points simultaneously
  3. New imaging technique evaluates nerve damage
  4. Researchers study Terahertz radiation’s impact on cellular function and gene expression


1. New hybrid imaging device shows promise in spotting hard-to-detect ovarian cancer

New hybrid imaging device shows promise in spotting hard-to-detect ovarian cancer

Co-registered images of malignant ovarian tissue obtained with the hybrid imaging device. From top to bottom: OCT image , ultrasound image, superimposed photoacoustic and ultrasound image and corresponding histology . Yellow diamond arrow: malignant tissue. Credit: University of Connecticut/Biomedical Optics Express.

hybrid imaging device

Time-lapse microscopy of a fruit fly epithelium in which a single cell is isolated from the remainder of the cell sheet using a single holographically-shaped laser pulse. Progression in time is color-coded from blue to red to white. Credit: Aroshan K. Jayasinghe.

hybrid imaging device 2

Time-lapse microscopy of a fruit fly epithelium in which a single cell is isolated from the remainder of the cell sheet using a single holographically-shaped laser pulse. The cell-to-be-isolated is marked with an asterisk in the first frame. Subsequent frames are at 6 s and 70 s after ablation. Credit: Aroshan K. Jayasinghe. .

By combining three previously unrelated imaging tools into one new device, a team of researchers from the University of Connecticut and the University of Southern California has proposed a new way to diagnose early-stage ovarian cancer in high-risk women through minimally invasive surgery. The new technique may be better than the current standard procedure of preemptively removing the ovaries.

Ovarian cancer has a low survival rate because a lack of reliable screening techniques usually means the disease remains hidden until the later stages. Now researchers have drawn on the unique advantages of multiple imaging tools to test a new way of spotting early-on the tissue irregularities that signal cancer.

For their diagnostic device, the researchers combined the contrast provided by photoacoustic imaging, the high-resolution subsurface imaging provided by optical coherence tomography, and the deeper tissue imaging provided by pulse-echo ultrasound. They tested their device, described by the team in the September issue of the Optical Society’s (OSA) open-access journal Biomedical Optics Express, by imaging both pig and human ovarian tissue, and correctly identified malignant tumors that were later confirmed by staining the tissue and examining it under a microscope. These initial tests were performed on tissue that had been surgically removed, but the diameter of the device – at only 5 mm – is small enough that it could potentially be inserted through a small slit to image tissue in live patients.

Paper: “Integrated optical coherence tomography, ultrasound and photoacoustic imaging for ovarian tissue characterization,” Yang et al., Biomedical Optics Express, Volume 2, Issue 9, pp.2551-2561.

2. Using lasers to vaporize tissue at multiple points simultaneously

Researchers at Vanderbilt University have developed a new technique that uses a single UV laser pulse to zap away biological tissue at multiple points simultaneously, a method that could help scientists study the mechanical forces at work as organisms grow and change shape.

UV lasers are a commonly-used tool for cutting into tissue, but the lasers usually make incisions by vaporizing one point at a time in a series of steps. If the initial laser pulse cuts into cells under tension, the tissue could spring back from the incision. This makes precise tasks, such as cutting around a single cell, difficult. The Vanderbilt team found a way around this problem by using a computer-controlled hologram to shape the phase profile of the UV pulse –basically applying a patterned delay onto different parts of the beam. When the pulse then passed through a lens, the altered phase profile yielded an interference pattern with bright spots at any user-desired pattern of points. Using this method, which can vaporize up to 30 points simultaneously, the researchers successfully isolated a single cell on a developing fruit fly embryo and then observed how the cell relaxed into a shape dictated solely by internal forces.

The technique, described in the September issue of the Optical Society’s (OSA) open-access journal Biomedical Optics Express, could be applied to other model organisms, such as frogs or zebra fish, to help answer outstanding questions in developmental biology. This knowledge may in turn guide bioengineers searching for ways to grow designer tissue.

Paper: “Holographic UV laser microsurgery,” Jayasinghe et al., Biomedical Optics Express, Vol. 2, Issue 9, pp. 2590-2599.

3. New imaging technique evaluates nerve damage

A new imaging technique could help doctors and researchers more accurately assess the extent of nerve damage and healing in a live patient. Researchers at Laval University in Québec and Harvard Medical School in Boston aimed lasers at rats’ damaged sciatic nerves to create images of the individual neurons’ insulating sheath called myelin. Physical trauma, repetitive stress, bacterial infections, genetic mutations, and neurodegenerative disorders such as multiple sclerosis can all cause neurons to lose myelin. The loss slows or halts the nerve’s transmission of electrical impulses and can result in symptoms such as numbness, pain, or poor muscle control.

Using their images of neurons, the researchers measured the thickness of the myelin at different locations and times after the rats’ sciatic nerve was damaged. Two weeks after injury the nerve’s myelin covering had thinned considerably, but at four weeks the nerve had begun to heal.

Traditionally, researchers could only obtain such myelin measurements by removing the nerve and slicing it into thin layers, a technique whose destructive nature prevented it from being used to evaluate nerve injuries in living patients. The new imaging method, described in the September issue of the Optical Society’s (OSA) open-access journal Biomedical Optics Express, holds promise as a diagnostic tool for doctors treating nerve damage or degenerative diseases, the researchers write.

Paper: "In vivo evaluation of demyelination and remyelination in a nerve crush injury model" Belanger et al., Biomedical Optics Express,Volume 2, Issue 9, pp. 2698-2708.

4. Researchers study Terahertz radiation's impact on cellular function and gene expression

Terahertz (THz) technologies show promise for myriad medical, military, security, and research applications ranging from the detection of cancer to airport security systems to shipment inspection to spectroscopy. Relatively little is known, however, about the effect of THz radiation on biological systems. So a team of researchers, led by Los Alamos National Laboratory, evaluated the cellular response of mouse stem cells exposed to THz radiation. They applied low-power radiation both from a pulsed broadband (centered at 10 THz) source and from a continuous wave (CW) laser (2.52 THz) source, and applied both modeling and empirical characterization and monitoring techniques to minimize the impact of radiation-induced increases in temperature.

The researchers determined that temperature increases were minimal, and that heat shock protein expression was unaffected, while the expression of certain other genes showed clear effects of the THz irradiation. As the researchers describe in the September issue of the Optical Society’s (OSA) open-access journal Biomedical Optics Express, mouse mesenchymal stem cells exposed to THz radiation exhibit specific changes in cellular function closely related to the gene expression. They believe further investigations involving a large number of genes and variation in THz radiation characteristics and exposure duration are needed to generalize their findings. They also say that more direct experimental investigations of THz radiation’s ability to induce specific openings of the DNA double strand are needed to fully determine how THz radiation may work through DNA dynamics to influence cellular function.

The team, led by Los Alamos National Lab, worked in collaboration with the Center for Integrated Nanotechnologies, a U.S. Department of Energy, Office of Basic Energy Sciences user facility at Los Alamos and Sandia National Laboratories, and with Harvard Medical School, and Beth Israel Deaconess Medical Center.

Paper: “Non-thermal effects of terahertz radiation on gene expression in mouse stem cells,” Biomedical Optics Express, Alexandrov et al., Volume 2, Issue 9, pp. 2679-2689.

EDITOR’S NOTE: For images or interviews with authors of the papers listed above, please contact Angela Stark, astark@osa.org or 202.416.1443. To get the monthly Biomedical Optics Express tip sheet, email astark@osa.org or follow @OpticalSociety on Twitter.

About Biomedical Optics Express
Biomedical Optics Express is OSA’s principal outlet for serving the biomedical optics community with rapid, open-access, peer-reviewed papers related to optics, photonics and imaging in the life sciences. The journal scope encompasses theoretical modeling and simulations, technology development, and biomedical studies and clinical applications. It is published by the Optical Society and edited by Joseph A. Izatt of Duke University. Biomedical Optics Express is an open-access journal and is available at no cost to readers online at http://www.OpticsInfoBase.org/BOE.

About OSA
Uniting more than 106,000 professionals from 134 countries, the Optical Society (OSA) brings together the global optics community through its programs and initiatives. Since 1916 OSA has worked to advance the common interests of the field, providing educational resources to the scientists, engineers and business leaders who work in the field by promoting the science of light and the advanced technologies made possible by optics and photonics. OSA publications, events, technical groups and programs foster optics knowledge and scientific collaboration among all those with an interest in optics and photonics. For more information, visit www.osa.org.

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