Biomedical subjects

David C Taylor

Publications and source records attributed to David C Taylor.

22 records · Page 2Linked to original sources

PubMed2003

Multidetector CT angiography of the aortoiliac system and lower extremities: a prospective comparison with digital subtraction angiography.

OBJECTIVE: Our objective was to determine whether multidetector CT (MDCT) angiography is an accurate and reliable method of revealing atheroocclusive disease of the aortoiliac system and the lower extremities compared with digital subtraction angiography (DSA). SUBJECTS AND METHODS: Forty-one patients with ischemic legs underwent both MDCT angiography and DSA of the aortoiliac system and the legs. The arterial supply of the legs was divided into 35 segments. Three independent observers rated each segment according to the maximal degree of arterial stenosis. Consensus interpretation was used to calculate the sensitivity and specificity of MDCT angiography in showing arterial occlusions and stenoses of at least 75%. Intertechnique agreement was measured for each anatomic segment, and interobserver agreement was calculated for both techniques. Agreement was quantified using the kappa statistic. RESULTS: The sensitivity and specificity of MDCT angiography for depicting arterial occlusions and stenoses of at least 75% were 88.6% and 97.7%, and 92.2% and 96.8%, respectively. Substantial intertechnique agreement (kappa > 0.4) was present in 102 (97.1%) of 105 arterial segments. Substantial interobserver agreement was present in 104 (99.0%) of 105 comparisons for both MDCT angiography and DSA with an average kappa value of 0.84 for CT and 0.78 for DSA. MDCT angiography showed more patent segments than DSA (1192 vs 1091). All nine segments seen on DSA and not seen on MDCT angiography were in the calves. Of 110 segments seen on MDCT angiography and not seen on DSA, 100 (90.9%) were in the calves. CONCLUSION: MDCT angiography was accurate in showing arterial atheroocclusive disease with reliability similar to DSA. MDCT angiography showed more vascular segments than DSA, particularly within calf vessels.

Adult↗

PubMed2002

A desaturase-like protein from white spruce is a Delta(9) desaturase.

Gymnospermae seed lipids are characterized by a high degree of desaturation, most having a Delta(9) double bond. By degenerate polymerase chain reaction (PCR) we have isolated a white spruce (Picea glauca) cDNA clone that encodes an amino acid sequence sharing a high degree of homology with other putative plant acyl-coenzyme A (CoA) Des9 desaturases. Both in vivo and in vitro expression studies in a Delta(9) desaturase-deficient yeast strain demonstrated the desaturation functionality of the white spruce clone, and gas chromatography-mass spectrometry (GC-MS) analyses confirmed the regioselectivity of the encoded enzyme. This is the first report of the functional characterization of a plant membrane-bound acyl-CoA-like protein Delta(9) desaturase by heterologous expression in yeast.

Amino Acid Sequence↗

PubMed2002

Restoring enzyme activity in nonfunctional low erucic acid Brassica napus fatty acid elongase 1 by a single amino acid substitution.

Genomic fatty acid elongation 1 (FAE1) clones from high erucic acid (HEA) Brassica napus, Brassica rapa and Brassica oleracea, and low erucic acid (LEA) B. napus cv. Westar, were amplified by PCR and expressed in yeast cells under the control of the strong galactose-inducible promoter. As expected, yeast cells expressing the FAE1 genes from HEA Brassica spp. synthesized very long chain monounsaturated fatty acids that are not normally found in yeast, while fatty acid profiles of yeast cells expressing the FAE1 gene from LEA B. napus were identical to control yeast samples. In agreement with published findings regarding different HEA and LEA B. napus cultivars, comparison of FAE1 protein sequences from HEA and LEA Brassicaceae revealed one crucial amino acid difference: the serine residue at position 282 of the HEA FAE1 sequences is substituted by phenylalanine in LEA B. napus cv. Westar. Using site directed mutagenesis, the phenylalanine 282 residue was substituted with a serine residue in the FAE1 polypeptide from B. napus cv. Westar, the mutated gene was expressed in yeast and GC analysis revealed the presence of very long chain monounsaturated fatty acids (VLCMFAs), indicating that the elongase activity was restored in the LEA FAE1 enzyme by the single amino acid substitution. Thus, for the first time, the low erucic acid trait in canola B. napus can be attributed to a single amino acid substitution which prevents the biosynthesis of the eicosenoic and erucic acids.

3-Oxoacyl-(Acyl-Carrier-Protein) Synthase↗

PubMedDate not supplied

Keratinized squamous cells in fine needle aspiration of the brain. Cytopathologic correlates and differential diagnosis.

OBJECTIVE: To analyze the differential diagnosis when keratinized squamous cells are found in a brain aspirate. STUDY DESIGN: Twenty cases of brain aspirates with keratinized squamous cells were retrieved (1982-2001). Diagnoses included craniopharyngioma (CP) (n = 11), metastatic squamous cell carcinoma (SCC) (n = 5), epidermoid cyst (EC) (n = 3) and Rathke cleft cyst (RCC) (n = 1). Aspirates were obtained under stereotactic radiologic (CT) guidance. Smears were stained with Diff-Quik or Papanicolaou stain, and cell block sections were stained with hematoxylin and eosin. Radiologic and histopathologic correlation with subsequent resection specimens was performed in selected cases. RESULTS: CP showed cellular smears with numerous keratinized squamous cells in a background of degenerated cellular and keratinaceous debris. Also noted were clusters of anucleate squamous cells, multinucleated giant cells, histiocytes, calcified debris and characteristic fragments of basaloid epithelial cells. Metastatic SCC showed single cells and tissue fragments of markedly atypical and focally keratinized cells with enlarged, hyperchromatic nuclei; prominent pleomorphism in a background of necrotic cellular debris and acute inflammatory exudate. EC showed numerous isolated keratinized squamous cells often with prominent keratohyaline granules and occasional parakeratotic cells in a relatively clean background. RCC showed single cells and aggregates of benign-appearing squamous cells admixed with numerous anucleate squames and hemosiderin-laden macrophages. Glandular-type epithelium was present only rarely. CONCLUSION: Squamous cell-containing lesions in the brain present a spectrum of pathologic entities. Although they all display the common morphologic denominator of keratinizing squamous cells, subtle cytomorphologic differences exist in these lesions, permitting an accurate cytopathologic diagnosis. Clinicardiologic features and anatomic location of the tumor in the brain are additionally helpful.

Adolescent↗