Biomedical subjects

Timothy W King

Publications and source records attributed to Timothy W King.

3 recordsLinked to original sources

PubMed2002

A technique for quantitative three-dimensional analysis of microvascular structure.

Research into angiogenesis and vascular microarchitecture has contributed to progress in a wide variety of biomedical fields, but increased understanding is limited, in part, by the available assays and imaging modalities. Techniques that allow quantitation of vascular microarchitecture are needed. A comprehensive method is presented that uses 6-microm-thick serial sections of frozen tissue samples, immunostaining for CD31, brightfield microscopy, automated alignment of two-dimensional serial sections, and volume rendering to produce high-resolution, three-dimensional, quantifiable images of microvascular structure. Application of the technique is shown by characterizing vascularization into a fibrin gel implanted against the skeletal muscle of rats and explanted after 7 days. Comparing measurements from automated and manually aligned MRI and fibrin samples verified quantitation. Automation removes concerns of observer bias or variation inherent in manual alignment and increases the speed of analysis. Analysis of the fibrin gel reveals a dense (4.3 +/- 1.1% endothelial cell density) network of tortuous (1.37 +/- 0.05 tortuosity) capillaries that replaces the gel as it degrades. There is a high level of void space (22.8 +/- 3.6%) in the gel, and average capillary length in the fibrovascular tissue was 93.0 +/- 7.4 microm. Data obtained from these automatically aligned images agreed with those obtained using manual analysis (no statistical difference), and the results are consistent with data from traditional methods.

Animals↗

PubMed2002

Aesthetic and functional outcomes using osseous or soft-tissue free flaps.

The authors compared functional and aesthetic outcomes following reconstruction of the posterior mandible (i.e., unilateral defects distal to the mental foramen) with free flaps containing vascularized bone (VBFs) or only soft-tissue (STFs). Fifty-eight reconstructions of the posterior mandible were performed with STFs (n=32) or VBFs (n=26) and were available for review. All patients (n=58) completed a functional outcome questionnaire containing questions about diet, oral competence, pain, trismus, speech, cosmesis, social reintegration, and return to work. Computer-assisted image analysis was performed comparing facial proportions of patients with STFs (n=10), VBFs (n=11), or unoperated controls (n=10). VBFs yielded statistically significantly superior functional scores compared to STFs in 5/12 categories. Normal scores were found for diet in 31 percent (10/32) vs. 21 percent (3/26) ( p=0.006); oral competence in 56 percent (18/32) vs. 35 percent (9/26) ( p=0.05); and speech in 47 percent (15/32) vs. 30 percent (7/26) ( p=0.026). VBF patients returned to public dining (72 percent, 23/32) more frequently than STF patients (35 percent, 9/26), ( p=0.003). VBFs yielded superior results for midline symmetry with a mean mandible deviation of 3.3+/-2.3 mm vs. 5.8+/-3.6 mm (STFs), and 1.2+/-0.7 mm (controls, p=0.001). An objective method for the evaluation of aesthetic and functional outcomes in posterior mandible reconstruction was developed. This method demonstrated that posterior mandible reconstruction with VBFs is associated with superior results in speech, diet, and midline symmetry. However, rigorous analyses of oropharyngeal soft-tissue defects and the radiation therapy protocols utilized, were not performed in this study. Without these additional analyses, one cannot definitively conclude that VBFs are superior to STFs.

Adult↗

PubMed2002

Quantification of vascular density using a semiautomated technique for immunostained specimens.

OBJECTIVE: To develop a semiautomated, quantitative techniquefor the assessment of vascular density in immunohistochemically stained tissue sections using diaminobenzidine tetrahydrochloride (DAB) and hematoxylin as chromagens. STUDY DESIGN: A semiautomated thresholding technique was developed to quantitate vascular density in tissue sections stained with anti-CD31 (1 degrees antibody). The immunohistochemically stained specimens were digitally imaged using a 24-bit color camera. The blue component of the RGB image was segmented using a variable high-pass filter. After thresholding, the segmented areas (CD31 positive) were quantified and vascular density determined. The validity of the method was verified by calculating the precision of the technique using the coefficient of repeatability and by quantifying its agreement with manual analysis according to the Bland-Altman approach. RESULTS: Vascular endothelial cells were specifically selected using anti-CD31 as the primary antibody and the appropriate horseradish peroxidase-conjugated secondary antibody. Utilizing the semiautomated thresholding technique, the separation of DAB-stained tissuefrom non-DAB-stained tissue was achieved. The method developed possesses a low coefficient of repeatability (0.49%), agrees well with manual assessment (mean difference = -0.29 +/- 0.92%), is highly automated and is user friendly. CONCLUSION: A novel semiautomated technique for the quantification of vascular density was developed. This technique provides a method for reproducible measurement of immunostaining procedures (immunohistochemistry, immunocytochemistry and in situ hybridization) utilizing immunoperoxidase techniques with DAB as a chromagen.

3,3'-Diaminobenzidine↗