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Biomedical subjects

L C Knight

Publications and source records attributed to L C Knight.

80 records · Page 5Linked to original sources
PubMed1979

Evaluation of retroperitoneum with computerized tomography and ultrasonography in patients with testicular tumors.

Results of CT and US examinations in 24 patients with testicular tumors yielded similar sensitivity and specificity in the diagnosis of enlarged retroperitoneal lymph nodes found at laparatomy. Therefore, the choice of either imaging modality may be influenced by other factors such as presence of abundant bowel gas, post-operative wounds, surgical clips in the abdomen, cachexia or obesity.

Adult↗
PubMed1979

Evaluation of three imaging instruments in dogs with liver hemotomas: concise communication.

Single-gamma emission computerized tomography (ECT) was compared with transmission computerized tomography (TCT) and scintillation-camera imaging (SC) in eight dogs with acute, solitary hematomas in the left liver lobe. The superior performance of TCT was attributed to its inherently better spatial resolution than those of ECT or SC, and to the fact that studies with TCT could be performed during apnea. ECT was more sensitive than SC to small changes in the spatial distribution of radionuclides. In addition, the ECT, by virtue of its sectioning capability, was more sensitive than is SC to differences in radionuclide concentrations at same depth in an organ.

Animals↗
PubMed1978

Sites of direct and indirect halogenation of albumin.

The sites of radiohalogenation in proteins vary with the labeling method and the pH of the labeling reaciton. We have directly halogenated albumin with carrier-free radioiodide by three methods (pH range 2.2--9.3), and with carrier-free radiobromide by the chloroperoxidase method (pH range 2.2--4.6). Albumin was also indirectly halogenated by attaching a radioiodinated acylating agent, N-succinimidyl-3-(4-hydroxyphenyl) propionate (SHPP). The labeled proteins were proteolyzed enzymatically at neutral pH and the labeled amino acids produced were analyzed by liquid chromatography. Iodination at pH 7 yielded predominantly monoiodotyrosine, but at lower pH, fewer tyrosyl residues are labeled and a greater number of unstable sulfur-iodine bonds are formed at cysteinyl residues. Bromination with chloroperoxidase resulted in a high degree of labeling of cysteinyl residues at pH 2.8, the condition for optimum activity of this halogenating enzyme. Indirect halogenation with SHPP resulted in labeling of mid-chain lysyl, histidyl and tyrosyl residues.

Bromine↗
PubMed1978

Comparison of In-111-labeled platelets and iodinated fibrinogen for the detection of deep vein thrombosis.

Indium-111-labeled platelets and I-125 fibrinogen were administered to dogs with experimentally induced deep-vein thrombosis. The thrombus uptake of both labeled compounds was studied as a function of thrombus age. In thrombi less than 24 hr old, thrombus-to-blood ratios for In-111 platelets were about twice as great as those obtained for I-125 fibrinogen. Excellent scintiphotos were obtained with In-111 platelets. In thrombi older than 24 hr, uptake of both agents was low, but good images were still obtained with In-111 platelets. The images in this case are not of thrombi, but rather of damaged vessel wall. Indium-111-labeled platelets are superior to iodinated fibrinogen for imaging fresh thrombi, but offer no advantage for thrombi over 24 hr old.

Animals↗
PubMed1977

Differences in the sites of iodination of proteins following four methods of radioiodination.

The rate of deiodination of radioiodinated proteins varies with the method of iodination. To elucidate differences in the iodinated protein labeled by various methods, we have hydrolyzed fibrinogen and several small peptides iodinated by the iodine monochloride, chloramine-T, electrolytic and enzymatic methods. Under conditions of either acidic or basic proteolysis, extensive deiodination occurred and the major product was I-. When a protease of Streptomyces griseus was used, radio-iodinated fibrinogen and other polypeptides were degraded to single iodinated amino acid residues and only a small yield of I-. The iodinated amino acids resulting from proteolysis were separated by ion-exchange chromatography. The iodine monochloride and enzymatic methods yielded largely iodotyrosine with small amounts of other iodinated amino acids. The chloramine-T product spectrum varied with the chloramine-T:protein ratio, whereas the electrolytic method yield was a complex function of the reaction conditions. The different methods of iodination lead to some differences in the site of iodination which correlate with stability of the protein-iodine bond.

Amino Acids↗
PubMed1977

In vitro stability and in vivo clearance of fibrinogen or serum albumin labeled with 77Br, 131I, or 125I by direct or indirect synthetic methods.

Conventional protein iodination involves the addition of an oxidizing agent to the protein solution. Through the use of the acylating agent N-succinimidyl-3(4-hydroxyphenyl)propionate, labeling can be accomplished without subjecting the protein to oxidizing conditions. Fibrinogen and serum albumin labeled with 131I and 77Br by this technique were compared with each other and with 125I-protein prepared by direct iodination using the ICI, chloramine-T, and lactoperoxidase methods. Iodinated proteins have two drawbacks: the high radiation dose accompanying 125I and 131I, and the ease of hydrolysis of the weak carbon-iodine bond. These drawbacks can be overcome by using 56-hr 77Br.

Acylation↗