Biomedical subjects

D Hsiang

Publications and source records attributed to D Hsiang.

3 recordsLinked to original sources

PubMed2002

Spectroscopy enhances the information content of optical mammography.

Near-infrared (NIR) diffuse optical spectroscopy and imaging may enhance existing technologies for breast cancer screening, diagnosis, and treatment. NIR techniques are based on quantitative measurements of functional contrast between healthy and diseased tissue. In this study we measured the spectral dependence of tissue absorption (mu(a)) and reduced scattering (mu'(s)) in the breasts of 30 healthy women and one woman with a fibroadenoma using a seven-wavelength frequency-domain photon migration probe. Subjects included pre- and postmenopausal women between the ages of 18 and 64. Multi-spectral measurements were used along with a four-component fit to determine the concentrations of de-oxy and oxy-hemoglobin, water and lipids in breast. The scattering spectral shape was also quantified. Our measurements demonstrate that the measured concentrations of NIR analytes correlate well with known breast physiology. Although the tissue scattering at a single wavelength was found to have little value as a functional parameter, the dependence of the scattering on wavelength provided key insights into breast composition and physiology. Lipids and scattering spectra in the breast were found to increase and decrease, respectively, with increasing body mass index. Simple calculations are also provided to demonstrate potential penalties from ignoring the contributions of water and lipids in breast measurements. Finally, water is shown to be a possible indicator for detecting a fibroadenoma, whereas the hemoglobin saturation was found to be a poor indicator. Multi-spectral measurements, compared to measurements restricted to one or two wavelengths, provide additional information that may be useful in managing breast disease.

Breast↗

PubMed2000

Automated DNA mutation analysis by single-strand conformation polymorphism using capillary electrophoresis with laser-induced fluorescence detection.

Automation is essential for rapid genetic-based mutation analysis in clinical laboratory to screen a large number of DNA samples. We propose in this report an automatic process using Beckman Coulter P/ACE capillary electrophoresis (CE) with laser-induced fluorescence (LIF) system to detect a single-point mutation in the codon 12 of human K-ras gene. Polymerase chain reaction (PCR) using a fluorescently labeled reverse primer and a plain forward primer to specifically amplify a selected 50 bp DNA fragment in human K-ras gene. The amplified DNA is placed on the sample tray of the CE system with a pre-programmed step for single-strand conformation polymorphism (SSCP) analysis. Sample injection and denaturation processes are performed online along with separation and real-time data analysis. The concept of automation for rapid DNA mutation analysis using CE-LIF system for SSCP is presented.

Automation↗

PubMed1997

Absence of K-ras mutations in the pancreatic parenchyma of patients with chronic pancreatitis.

BACKGROUND: Human pancreatic cancers exhibit a high frequency of K-ras mutations. METHODS: In this study we used oligonucleotide specific hybridization to compare the frequency of K-ras mutations in genomic DNA samples prepared from 21 normal pancreatic tissues, 26 chronic pancreatitis tissues, and 24 pancreatic cancers. RESULTS: None of the DNA samples from normal or chronic pancreatitis tissues exhibited a K-ras mutation at codons 12 or 13 of K-ras. In contrast, 17 of 24 DNA pancreatic cancers harbored a K-ras mutation. Validity of the methodology was confirmed by genotyping 7 human pancreatic cancer cell lines. Analysis of focal areas of proliferation from 5 chronic pancreatitis and 5 pancreatic cancer samples processed by selective ultraviolet radiation fractionation (SURF), a procedure used to enrich DNA isolation from foci of proliferating cells, revealed complete concordance with total genomic DNA analysis. CONCLUSIONS: These findings indicate that the pancreatic parenchyma in patients with chronic pancreatitis most frequently does not possess a K-ras mutation.

Adolescent↗