Robert E. O'Mara

Radionuclide skeletal imaging and single photon emission computed tomography in suspected internal derangements of the temporomandibular joint

Fifty one subjects who had pain involving the temporomandibular joint were evaluated using multidirectional tomography, arthrography, conventional nuclear scanning, and single photon emission computed tomography (SPECT) to assess the association of arthritis of the temporomandibular joint with internal derangements related to meniscal dysfunction. Five (56%) of the nine subjects who had normal arthrograms and normal multidirectional tomograms had SPECT scans that were positive for osseous changes. Twenty-two subjects (27 temporomandibular joints) were diagnosed by arthrography to have meniscal displacement with reduction. Multidirectional tomograms of the 27 joints were positive for osseous changes in five (18%) joints, whereas SPECT scans were positive in nine (70%) joints. Twenty subjects (20 temporomandibular joints) had an arthrographic diagnosis of meniscal displacement without reduction. Multidirectional tomograms of the 20 joints were positive for osseous changes in 14 (70%) joints, and SPECT scans were positive in 16 (80%) joints (P less than 0.001 vs control group). Initial observations with SPECT indicate it is a promising imaging method for detecting and staging osseous disease of the TMJ related to meniscal dysfunction.

Technetium Tc 99m plasmin in the diagnosis of inflammatory disease

The localization characteristics of technetium Tc 99m plasmin were studied in experimental animals to investigate the use of99mTc-plasmin for imaging inflammatory processes. At various times after abscess induction using turpentine in rats, the in vivo distribution properties of99mTc-plasmin, gallium citrate Ga 67,125I-fibrinogen, and99mTc-human serum albumin (HSA) were studied by gamma-camera imaging. The in vivo binding of each radiopharmaceutical was also tested in rat and human plasma clots. Region-of-interest analyses of gamma-camera images showed relatively poor99mTc-plasmin localization at sites of abscess formation. The ratio of abscess-to-control activity of this radiopharmaceutical did not exceed that of67Ga,125I-fibrinogen, or99mTc-HSA. In vitro assays of each of the radiopharmaceuticals in plasma clots showed99mTc-phasmin and125I-fibrinogen to have the best localization characteristics.

Changes in Markers of Epithelial Permeability and Inflammation in Chronic Smokers Switching to a Nonburning Tobacco Device (Eclipse)

Eclipse, produced by R. J. Reynolds Tobacco Company, is a potential reduced exposure product (PREP) that heats rather than burns tobacco. We hypothesized that switching to Eclipse would result in relative normalization of pulmonary epithelial permeability, airway inflammation, and blood leukocyte activation in current smokers. We assessed 10 healthy smokers (aged 21-50 years, 19+/-8 pack-years) at baseline and after 2 and 4 weeks of switching to Eclipse, for symptoms, pulmonary function, airway inflammation, lung clearance of (99m)technicium-diethylenetriaminepentaacetic acid, and blood leukocyte activation and production of reactive oxygen species. Values were compared before and after Eclipse use and with those of healthy, lifetime nonsmokers (aged 18-53 years). Compared with baseline values before switching to Eclipse, lung permeability half-time increased from 33+/-3 to 43+/-6 min (p = .017) after 2 weeks and to 44+/-7 min (p = .10) after 4 weeks of Eclipse use. Carboxyhemoglobin levels increased from 5%+/-2% to 7%+/-2% (p<.01) at 4 weeks. Compared with smoking the usual brand of cigarettes, after smoking Eclipse the percentage of natural killer cells, the expression of intercellular adhesion molecule-1 on monocytes, and the expression of CD45RO on T cells showed significant improvement. However, expression of other surface markers, notably CD23 on monocytes, became more abnormal. Production of reactive oxygen species by smokers neutrophils and monocytes increased further with Eclipse use. We found no significant effects on pulmonary function, cells in induced sputum, or exhaled nitric oxide. Switching to Eclipse reduces alveolar epithelial injury in some smokers but may increase carboxyhemoglobin levels and oxidative stress.

The interactions of99mTc phosphorus radiopharmaceuticals and human serum proteins

Dialysis and precipitation methods have been used to study the binding affinity of selected technetium-99m phosphorus radiopharmaceuticals to human serum proteins. The binding affinities of three different99mTc bone imaging agents were found to be inversely related to their respective clearance rates from blood in vivo. The binding order showed99mTcPPi>99mTcHEDP>99mTcMDP. The99mTc phosphorus radiopharmaceuticals were bound primarily to alpha globulins. The results suggest that the binding of99mTc phosphorus radiopharmaceuticals to human serum proteins in blood is largely determined by their affinities to the alpha globulins.