The design and application of DNA chips for early detection of SARS-CoV from clinical samples

Background:

SARS coronavirus has been identified as the cause of severe acute respiratory syndrome (SARS). Few tests allow confirmation or exclusion of SARS within the first few days of infection. A gene chip is a useful tool for the study of microbial infections mainly for its capability of performing multi-target analysis in a single test.

Objectives:

Investigate the possibility of early detection of SARS virus from clinical samples using the gene chip-based method.

Study design:

We purified RNA from SARS-CoV obtained from routinely collected peripheral blood and sputum samples of 34 patients who had been identified as probable SARS patients by following the interim U.S. case definition. Four segments of the SARS-CoV were amplified using reverse transcription-nested PCR and the products examined using the 70-mer gene chips for SARS-CoV detection.

Results:

A blind-test of both peripheral blood and sputum specimens lead to the positive detection of SARS-CoV in 31 out of 34 patients. SARS-CoV was not found in peripheral blood or sputum specimens from three patients. Two of the 34 patients were only 3 days post-onset of symptoms and were subsequently confirmed to be SARS positive. Our results indicate that the gene chip-based molecular test is specific for SARS-CoV and allows early detection of patients with SARS with detection rate about 8% higher than the single PCR test when the sputum sample is available.

Using holographically generated corrector plates to fabricate low f/No. HOE objectives and collimators

We describe a double wavelength shift recording scheme for constructing holographic optical element (HOE) objectives and collimating lenses. The lenses are fabricated at intermediate wavelengths for use in a longer wavelength region. A holographic corrector plate is generated with a third wavelength that is the shortest of the three. Aberration of the HOE is compensated by inserting the corrector plate in one of the beams used in the construction process.

Reflection display of rainbow holograms

In this paper experimental results and a detailed analysis of a method for reflection display of rainbow holograms are presented. A method for noncontact reflection display is put forward. High quality reconstructed images can be obtained by simply placing a mirror at a proper distance behind the holograms. Essential requirements are derived to avoid interference fringes and unacceptable image blur. The diffraction efficiency which may be close to or even higher than that of transmission display in some conditions is also discussed. Experimental results are presented which fully coincide with the analysis.

Diffraction-limited recording scheme in astigmatic rainbow holography

A lensless single-slit imaging system is employed in the recording scheme of the astigmatic rainbow holographic process. The resulting hologram forms an acceptable deep bright image under white-light illumination.

Aperture conjugation technique in astigmatic rainbow holography

A slit image conjugation technique using an astigmatic reference beam in astigmatic rainbow holography is developed. When the primary image is reconstructed with a white light point source, a wide-view orthoscope quasi-monochromatic holographic image will be revealed. Experimental results are also included.