In vivo kinetics of canine leukocytes labeled with technetium-99m HM-PAO and indium-111 tropolonate. (49/66)

Two weeks after the introduction of osteomyelitis in three dogs, autologous leukocytes were dual-labeled with both [99mTc]HM-PAO and [111In]tropolonate, and reinjected. Blood sampling and imaging were then performed. Two weeks later, the same dogs received simultaneous injections of singly-labeled [99mTc]WBC and [111In]WBC for comparison. For both studies, blood samples were drawn over 6 hr to determine the respective blood clearance half-time (TB) and % recovery (%R0) of cell-bound radioactivity. There were no significant differences in the average TB results of the 99mTc and 111In groups, either within or between the dual- and singly-labeled studies. The %R0 of singly-labeled [99mTc]WBC was about half that of the other groups (p less than 0.01); however, this difference was attributed to the dissimilar radiochemical purity of the [99mTc]HM-PAO reagents. Region of interest analysis of the 6 and 24 hr images revealed no significant differences between either cell label in the relative or absolute in vivo uptake at known sites of osteomyelitis, noninfected surgery, and normal bone marrow.  (+info)

A fluorescence stopped flow study of the competition and displacement kinetics of podophyllotoxin and the colchicine analog 2-methoxy-5-(2',3',4'-trimethoxyphenyl) tropone on tubulin. (50/66)

The colchicine analog 2-methoxy-5-(2',3',4'-trimethoxyphenol) tropone (AC) was used as a fluorescent probe to study the binding kinetics of podophyllotoxin at high concentrations. The observed pseudo-first order rate constant showed a linear concentration dependence up to 1 mM. The bimolecular rate constant (195 M-1 s-1 at 15 degrees C) and the activation energy (57 kJ/mol) correspond perfectly with those previously determined in the submicromolar range (Cortese, F., Bhattacharyya, B., and Wolf, J. (1977) J. Biol. Chem. 252, 1134-1140). Displacement kinetics of bound AC by podophyllotoxin, allow the determination of the dissociation rate constants for AC. By studying the temperature dependence, and combining with the binding rate constants previously determined (Engelborghs, Y., and Fitzgerald, T.J. (1986) Ann. N.Y. Acad. Sci. 466, 709-717) a full characterization of the kinetic pathway is possible. This is shown to differ considerably from the pathway of colchicine binding.  (+info)

Clinical comparison of indium-111 acetylacetone and indium-111 tropolone granulocytes. (51/66)

This clinical study compares the efficacy of two 111In white blood cells preparations. Seventy-six patients were imaged after an injection of granulocytes (GRAN) isolated on a Ficoll-Hypaque gradient and labeled with [111In]acetylacetone (ACAC) in saline; 105 patients were imaged after an injection of GRAN isolated on a metrizamide-plasma gradient and labeled with [111In]tropolone (TROP) in plasma. Early (2-4 hr), intermediate (4-6 hr), and delayed (24 hr) images were obtained. The specificity was quite high (94-100%) in both preparations and no statistical differences could be found. The sensitivity for ACAC-GRAN for the early, intermediate, and delayed images were 39%, 63%, and 64%, respectively; for TROP-GRAN it was 80%, 89%, and 92%, respectively. In all cases the TROP-GRAN images were significantly more sensitive than the ACAC-GRAN images obtained at the same time after injection (p less than 0.001 for early and delayed images, 0.01 less than p less than 0.025 for intermediate images). For ACAC-GRAN the intermediate and delayed images were significantly more sensitive than the early images, while no significant difference could be found for TROP-GRAN. In a blinded experiment, the ability of TROP-GRAN to demonstrate a lesion was compared to that of ACAC-GRAN. TROP-GRAN demonstrated the lesions better than ACAC-GRAN, both in the early and late images (p less than 0.001). TROP-GRAN visualization scores at 4-6 hr equaled those obtained 24 hr after injection. In conclusion, GRAN separated and labeled in plasma with TROP are superior to those separated and labeled in saline with ACAC in three ways: higher visualization scores, earlier visualization of the lesion, and greater sensitivity.  (+info)

No difference in sensitivity for occult infection between tropolone- and oxine-labeled indium-111 leukocytes. (52/66)

There is considerable disagreement as to whether oxine or tropolone is the best labeling agent for indium leukocytes. We have previously looked at the sensitivity of oxine-labeled 111In leukocyte scans for occult infections and now present a similar group of patients imaged with tropolone-labeled 111In leukocytes. Thirty-four patients (38 studies) with possible occult infection were prospectively studied. Patients were imaged 1-4 hr after injection and again at 24 hr postinjection. The early tropolone images had a sensitivity of 53% while the delayed images at 24 hr had a sensitivity of 93%. Based on a previous study, oxine-labeled leukocyte scans have an early sensitivity of 33% and a delayed sensitivity (at 24 hr) of 95%. The differences in sensitivity between oxine and tropolone when imaged early and at 24 hr were not statistically significant. We conclude that there is no significant difference in the ability to detect infection between oxine- and tropolone-labeled leukocytes, both early at 1-4 hr, and on delayed imaging 24 hr after injection.  (+info)

Gallium-68 lipophilic complexes for labeling platelets. (53/66)

Generator produced 68Ga-labeled platelets could be useful for positron emission tomographic (PET) studies of thrombosis or atherosclerosis. To label platelets with 68Ga, we have studied the effects of trace metals in elutions of 68Ga from 68Ge. Studies were conducted on the formation of lipophilic 68Ga complexes 8-hydroxyquinoline, tropolone, and mercaptopyridine-N-oxide (MPO). Parameters such as pH, buffers, concentration of ligand, and stability with time were investigated. High performance liquid chromatography and instant thin layer chromatography were used to quantitate formation of the 68Ga complex. Platelets from human, dog, and rabbit plasma were incubated with the 68Ga complexes and the percent labeling determined. Accumulation of platelets in the catheter scraped aorta of the rabbit was determined by PET imaging, tissue counting, and autoradiography. Gallium-68 MPO gave 40-60% labeling of rabbit platelets with higher accumulation in the scraped aorta compared to the normal.  (+info)

Biosynthesis of algal pheromones. A model study with the composite Senecio isatideus. (54/66)

Several cyclic and alicyclic C11 hydrocarbons have been shown to act as gamete releasing and/or attracting pheromones during sexual reproduction of brown algae (Phaeophyceae). The same compounds are also found in the essential oils of various plants, of which the occurrence of the cycloheptadiene-pheromone ectocarpene in Senecio isatideus (Compositae) is noteworthy. Administration of [3H]dodeca-3,6,9-trienoic acid to cuttings of this plant leads to incorporation of radioactivity into ectocarpene. Double-bond-deuterated nona-3,6-dienoic acid is converted to fucoserratene, the pheromone of several Fucales, which is certainly not present among the hydrocarbons of Senecio. This proves that the pool of medium-chain, multiply unsaturated fatty acids includes precursors of all types of highly unsaturated hydrocarbons. Appropriately labelled (deuterium markers) fatty acid homologues were synthesized and applied to Senecio plantlets to unravel the mechanistic aspects. The results strongly suggest radical initiation of the pheromone biosynthesis by abstraction of a single hydrogen from a 1,4-pentadienyl segment of the fatty acid followed by oxidation to the corresponding cation. This causes fragmentation of the reactive intermediate into an olefine and carbon dioxide by neighbouring-group participation of the flanking double bonds. A tentative biosynthetic scheme is deduced from the experimental results which also sets the stereochemistry of the algal pheromones into a uniform mechanistic concept.  (+info)

Amino acid flux and protein synthesis after exposure of rats to either Diplococcus pneumoniae or Salmonella typhimurium. (55/66)

At 26 h after inoculation of rats with Diplococcus pneumoniae, the serum concentrations of 10 and 20 individual amino acids were lower than corresponding values observed in pair-fed controls. In contrast, only 2 of 20 serum amino acids were similarly decreased in rats inoculated with Salmonella typhimurium. Despite these serum differences, a greater accumulation of labeled non-metabolizable amino acids occurred in the livers of rats infected with S. typhimurium. These data suggested a greater increase in the flux of amino acids from muscle to liver in the rats infected with S. typhimurium as compared to those infected with D. pneumoniae. A similar increase in serum protein synthesis was observed in rats infected with D. pneumoniae or S. typhimurium. However, with the latter infection, a larger percentage of the amino acids appeared to be utilized as a source of energy in addition to their role as precursors of proteins.  (+info)

Contact allergy from Frullania and respiratory allergy from Thuja. (56/66)

Occupational allergic contact dermatitis in 52 forest-workers was caused by sesquiterpene lactones from liverworts (Frullania) and by usnic acid from lichens which grow on various trees including cedar (Thuja). Occupational asthma and rhinitis in 35 wood-workers was caused by wood dust of western red cedar (Thuja plicata). Characteristically, the respiratory symptoms occurred in the evening and at night and not during working hours; inhalation challenge with plicatic acid from the wood provoked immediate, late or dual (combined immediate and late) asthmatic reactions. Another class of compounds, tropolones, derived from Thuja plicata wood, was responsible for dermatitis in a wood-worker. These distinct industrial hazards in two groups of workers at the tree-felling and wood-working levels in the forest-products industry can be identified by clinical history and examination supplemented by specific cutaneous or respiratory clinical investigation.  (+info)