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Biomedical subjects

D C Baker

Publications and source records attributed to D C Baker.

149 records · Page 9Linked to original sources
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Pulmonary thromboembolism in 29 dogs: 1985-1995.

Pulmonary thromboembolism (PTE) occurs as a complication to a number of commonly encountered clinical diseases. Antemortem recognition of this life-threatening disorder is hampered by nonspecificity of clinical signs. This retrospective study was performed to analyze clinical features, laboratory findings, imaging abnormalities, and concurrent postmortem diagnoses in 29 dogs with confirmed pulmonary embolism. A variety of clinicopathologic and radiographic abnormalities were noted but there were no pathognomonic findings for PTE. Arterial blood gas analyses were performed in 15 (52%) of 29 dogs; 12 (80%) of 15 exhibited hypoxemia and 15 (100%) of 15 had increased alveolar-arterial oxygen gradients. Response to supplemental O2 was variable and did not correlate with the presence or absence of additional pulmonary pathology on postmortem. At postmortem, 25 (86%) of 29 dogs had grossly visible emboli, 17 (59%) of 29 dogs had multiple disease processes, and 16 (55%) of 29 dogs had additional pulmonary pathology. PTE was suspected antemortem in 11 (38%) of 29 dogs. In dogs with respiratory signs consistent with PTE, the condition was a differential diagnosis in 11 of 17 animals; all had diseases previously reported to be associated with PTE. Neoplasia, systemic bacterial disease, and immune-mediated hemolytic anemia were diagnosed most frequently.

Animals↗
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A comparison of dobutamine infusion to exercise as a cardiac stress test in healthy horses.

This study was done to determine whether administration of dobutamine would produce echocardiographic and electrocardiographic alterations comparable to those induced by treadmill exercise in healthy horses. Fourteen horses received maximal treadmill exercise and, separately, intravenous dobutamine infusion up to a maximum rate of 50 microg/kg/min. Ten of the 14 horses were euthanized, and the myocardial tissues were examined grossly and histopathologically. No significant differences were found in the chronotropic effects of dobutamine and exercise (P = .905). Dobutamine induced greater interventricular septal thickening during systole (dobutamine = 4.78 cm, exercise = 4.03 cm; P = .004). and greater left ventricular diameters during diastole (dobutamine = 9.73 cm, exercise = 9.26 cm; P = .037), than did exercise treatment. Horses exhibited transient signs of sweating and restlessness during infusion of moderate to maximum doses of dobutamine. Ventricular ectopy seen in 11 of 14 horses was attributed to the arrhythmogenic properties of dobutamine, as well as to increased vagal tone present at low dobutamine doses. Myocardial lesions characteristic of catecholamine myotoxicity were present in 2 of the 10 horses examined. Although dobutamine induces chronotropic and inotropic changes similar to those induced by exercise, the use of high-dose dobutamine as a cardiac stressor in horses cannot be advocated because of potential development of arrhythmias or myotoxicity.

Adrenergic beta-Agonists↗
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Concentration of galegine in Verbesina encelioides and Galega oficinalis and the toxic and pathologic effects induced by the plants.

Verbesina encelioides administered to sheep by gavage induced clinical signs of toxicity and pathologic lesions identical to those induced by Galega officinalis. Sheep had compromised respiratory function with shallow, rapid respiration and frothy exudate from the nares. Affected animals necropsied at time of death presented with hydrothorax with as much as 2 to 3 L of straw-colored thoracic fluid with fibrin tags and congestion and edema of the lungs. The trachea and lung airways contained frothy material with fibrin strands. In some cases, subendocardial hemorrhage of the left ventricle was present. Galegine, a guanidine compound believed to be responsible for these effects, was found at an average concentration of about 0.46% in Galega and at 0.08% in the Verbesina collection that induced toxicosis. While G. officinalis is a known poisonous plant, its very limited distribution in the U.S. causes it to be of minor importance. V. encelioides, however, is widely distributed in the U.S. and presents a potential hazard for grazing livestock. Verbesina may have been responsible for past livestock deaths in the U.S., and thus should be classified as a poisonous plant.

Animals↗
PubMedDate not supplied

Characterization of 2',3'-dideoxycytidine diphosphocholine and 2',3'-dideoxycytidine diphosphoethanolamine. Prominent phosphodiester metabolites of the anti-HIV nucleoside 2',3'-dideoxycytidine.

2',3'-Dideoxycytidine (ddCyd) is among the most potent of the anti-human immunodeficiency virus (HIV) agents of the dideoxynucleoside class. Its pharmacologically active metabolite 2',3'-dideoxycytidine 5'-triphosphate (ddCTP) is an effective inhibitor of HIV reverse transcriptase and thus of HIV replication. ddCyd differs, however, from other dideoxynucleoside agents such as 3'-azido-3'-deoxythymidine and 2',3'-dideoxyinosine in its capacity to generate phosphodiester metabolites (i.e. ddCDP choline and ddCDP ethanolamine). We have synthesized and characterized these two diesters, and established their identity with the metabolites formed in ddCyd-treated Molt-4 cells. Toward this end, the biologically generated metabolites have been isolated on a preparative scale and compared with the synthetic compounds mass spectroscopically, chromatographically, and enzymatically (i.e. their relative susceptibility to the catabolic enzymes alkaline phosphatase and venom phosphodiesterase). The concentration reached by each of these two phosphodiesters within cells can, under certain conditions, equal or exceed that of ddCTP, and their half-times of disappearance are long, indicating that they may serve as depot forms of ddCyd. The possible role of these phosphodiesters in contributing to the unusual toxicity of ddCyd is discussed.

Cells, Cultured↗