Biomedical subjects

John Butler

Publications and source records attributed to John Butler.

39 records · Page 3Linked to original sources

PubMedDate not supplied

In vivo absorption, scattering, and physiologic properties of 58 malignant breast tumors determined by broadband diffuse optical spectroscopy.

Diffuse optical imaging (DOI) may be a beneficial diagnostic method for women with mammographically dense breast tissue. In order to evaluate the utility of DOI, we are developing broadband diffuse optical spectroscopy (DOS) to characterize the functional origins of optical signals in breast cancer patients. Broadband DOS combines multifrequency intensity-modulated and continuous-wave near-infrared light to quantify tissue absorption and scattering spectra from 650 to 1000 nm. Values of intrinsic physiological properties (oxy- and deoxy-hemoglobin, water, lipid, and scatter power) derived from absorption and scattering spectra provide detailed information on breast physiology. We present the results of clinical studies of 58 stage II/III malignant breast tumors using a noninvasive, handheld, broadband DOS probe. On average, eight positions were scanned over tumor and contralateral normal breast for each subject. Intrinsic physiological properties were statistically significantly different for malignant vs. normal tissues for all subjects, without patient age or tumor size/type stratification. Breast tissues containing malignant tumors displayed reduced lipid content ( approximately 20%) and increased water, deoxy-, and oxy-hemoglobin (>50% each) compared to normal breast tissues. Functional perturbations by the tumor were significantly larger than functional variations in normal tissues. A tissue optical index (TOI) derived from intrinsic physiological properties yielded an average two-fold contrast difference between malignant tumors and intrinsic tissue properties. Our results demonstrate that intrinsic optical signals can be influenced by functional perturbations characteristic of malignant transformation; cellular metabolism, extracellular matrix composition, and angiogenesis. Our findings further underscore the importance of broadband measurements and patient age stratification in breast cancer DOI.

Adolescent↗

PubMedDate not supplied

The role of diffuse optical spectroscopy in the clinical management of breast cancer.

Diffuse optical spectroscopy (DOS) of breast tissue provides quantitative, functional information based on optical absorption and scattering properties that cannot be obtained with other radiographic methods. DOS-measured absorption spectra are used to determine the tissue concentrations of deoxyhemoglobin (Hb-R), oxyhemoglobin (Hb-O2), lipid, and water (H2O), as well as to provide an index of tissue hemoglobin oxygen saturation (StO2). Tissue-scattering spectra provide insight into epithelial, collagen, and lipid contributions to breast density. Clinical studies of women with malignant tumors show that DOS is sensitive to processes such as increased tissue vascularization, hypoxia, and edema. In studies of healthy women, DOS detects variations in breast physiology associated with menopausal status, menstrual cycle changes, and hormone replacement. Current research involves using DOS to monitor tumor response to therapy and the co-registration of DOS with magnetic resonance imaging. By correlating DOS-derived parameters with lesion pathology and specific molecular markers, we anticipate that composite "tissue optical indices" can be developed that non-invasively characterize both tumor and normal breast-tissue function.

Biophysical Phenomena↗

PubMedDate not supplied

Activity profile of the novel aziridinylbenzoquinones MeDZQ and RH1 in human tumour xenografts.

BACKGROUND: RH1 and MeDZQ represent novel aziridinylbenzoquinones that can be activated by DT-diaphorase to form unique DNA lesions. RH1 is due to enter a phase 1 clinical trial in the United Kingdom in the summer of 2003, where pharmacodynamic monitoring of DT-diaphorase will be performed. MATERIALS AND METHODS: The antitumour efficacy of RH1 and MeDZQ has been studied in 4 human xenografts (3 non-small cell lung cancer and 1 colon cancer), and compared to the level of constitutive DT-Diaphorase activity measured by the DCPIP assay. RESULTS: The 4 xenografts exhibited a wide range of DT-diaphorase activity (4.8-303 nmol/min/mg). Greater antitumour activity was recorded in the xenografts expressing high levels of DT-diaphorase (e.g. NX002, DT-diaphorase activity, 303 +/- 52 nmol/min/mg, T/C to MeDZQ, 33.3% and to RH1, 43.4%). CONCLUSION: These data add in vivo support to a role for DT-Diaphorase in the antitumour activity of RH1.

Animals↗