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C Smith

Publications and source records attributed to C Smith.

At least 775 records · Page 43Linked to original sources
PubMed1989

Evaluation of cardiopulmonary devices on chest radiographs: digital vs analog radiographs.

We compared digital and analog radiographs of the chest for use in detecting and evaluating a variety of cardiopulmonary devices in 40 patients. The devices included 23 endotracheal tubes, 21 Swan-Ganz catheters, 14 central venous pressure catheters, 11 prosthetic valves, 10 chest tubes, six pacemaker wires, and five intraaortic balloon pumps. Each patient had at least one device, with a maximum of five devices (average, 2.3). Forty digital/analog film pairs were compared by five radiologists, who assigned confidence levels for various judgments about each device. The results showed that there were no statistically significant differences in the identification of the devices except for prosthetic valves (all valves were detected on digital radiographs, compared with 62% on analog radiographs). The devices were detected on 96% of the digital radiographs and 90% of the analog radiographs. Although digital and analog radiographs were comparable for detection of most devices, the digital radiographs allowed greater confidence in the identification of the devices and in the identification of the tip and course of Swan-Ganz and central venous pressure catheters.

Catheterization↗
PubMed1989

Multiple ovulation and embryo manipulation in the improvement of beef cattle: relative theoretical rates of genetic change.

Theoretical rates of annual genetic responses to selection in beef cattle were compared for conventional and multiple ovulation and embryo transfer (MOET) breeding schemes. Several combinations of replacement policy, mating ratio and type of selection were considered for both schemes with low, medium and high heritabilities. For MOET, four rates of embryo transfers per donor were used to represent low to moderate MOET levels. The results indicated that annual genetic responses to selection could be up to 1.3, 1.6 and 1.8 times as great for MOET compared with conventional breeding for traits of low, medium and high heritability, respectively; however, the annual inbreeding rates also were high for the MOET schemes considered. Embryo splitting, or cloning, was shown to increase accuracy of selection by 8 to 35% through the production of identical genotypes. The use of MOET in conjunction with embryo splitting in elite nucleus units could substantially increase genetic improvement for traits with low, medium and high heritabilities in beef cattle populations.

Animals↗
PubMed1989

Studies on the mechanism of methanol poisoning: purification and comparison of rat and human liver 10-formyltetrahydrofolate dehydrogenase.

Methanol poisoning in primates and humans is due to formate accumulation as a result of low rates of formate oxidation. This toxicity is not seen in rats, where formate oxidation rates are high. Formate oxidation in vivo is dependent on hepatic tetrahydrofolate levels and on the activity of the enzyme 10-formyl-tetrahydrofolate (10-formyl-H4folate) dehydrogenase (EC 1.5.1.6). Because hepatic 10-formyl-H4folate dehydrogenase activity is lower in human liver than in rat liver, studies were performed investigating the properties of this enzyme in rat and human liver. 10-Formyl-H4folate dehydrogenase was purified to homogeneity from rat and human liver and was found to possess similar subunit molecular weights on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (96,000). N-Terminal amino acid analysis of the pure proteins showed an identical sequence for the first 16 amino acids. Antibodies raised in rabbits against the rat liver enzyme were inhibitory toward the activity of both rat and human liver enzymes and appeared to recognize only the 10-formyl-H4folate dehydrogenase in cytosolic preparations of rat and human liver. Immunoblots of pure rat and human liver 10-formyl-H4folate dehydrogenase showed similar staining intensity. It is concluded that rat and human liver 10-formyl-H4folate dehydrogenase possess very similar properties and that the activity of the enzyme in human liver is lower than that of rat liver, due to a reduced amount of enzyme protein in human liver. This may be an important factor in regulating formate oxidation in humans and may explain, in part, the accumulation of formate and the mechanism of toxicity of methanol in humans.

Amino Acid Sequence↗
PubMed1989

AIDS discrimination.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Efficacy of directed percutaneous fine-needle aspiration cytology in the diagnosis of intra-abdominal masses.

Directed percutaneous fine-needle aspiration (FNA) cytology was performed on 113 patients with intra-abdominal masses. The 47 male and 56 female patients had a median age of 56 years (range, 17 to 83 years). Computed tomography (CT) was used to localize the needle in 90 cases, and ultrasonography was used in the remaining 24 cases. The predominant sites aspirated were the liver (n = 40), pancreas (n = 23), and pelvis (n = 14). Seventy-eight of the 113 patients had a malignant neoplasm. Fine-needle aspiration cytology correctly identified 63 (88%) of the 78 cases. There were no false-positive studies. Computed tomography and UTZ ultrasonography were equally sensitive in detecting malignant neoplasms. In 38 patients with a history of previously treated malignant neoplasm, percutaneous aspiration cytology confirmed the presence of recurrent disease in 24 (75%) of 32 patients. Results of aspiration cytology obviated the need for a diagnostic laparotomy in 51 (65%) of the 78 patients with a malignant neoplasm. There was no serious morbidity or mortality associated with the procedure. We conclude that CT/ultrasonography-directed percutaneous FNA cytology is the procedure of choice in the workup of patients with intra-abdominal masses. The specificity is 100% and sensitivity is 90%. It is particularly useful in patients with extensive disease that would not be palliated by operation.

Abdominal Neoplasms↗
PubMed1988

Collisional activation decomposition of actinomycins using tandem mass spectrometry.

The collisional activation (xenon) decomposition of actinomycin V, dactinomycin, 7-nitrodactinomycin, 7-aminodactinomycin, and a mixture of dactinomycin, actinomycin C1 and actinomycin C2 was studied using a triple-quadrupole mass spectrometer with fast atom bombardment (xenon) ionization. Fragmentation pathways of the structurally significant ions were rationalized by assuming an initial McLafferty rearrangement at the ester linkage between the methylvaline and the threonine of both rings to form linear pentapeptides, followed by fragmentation in either pentapeptide yielding typical sequence ions and sequence cleavages from both rings.

Dactinomycin↗