Lynn R. Hendershott

Does inhaled pollen enter the sinus cavities

BACKGROUND While there is evidence of an increased incidence of sinusitis in patients with allergic rhinitis, it is unclear whether an allergic process occurs in the sinus tissues per se. OBJECTIVE The purpose of this study was to determine whether inhaled pollen reaches the sinus mucosa. METHODS Tc99m labeled ragweed pollen was inhaled by five non-atopic adults. Imaging studies of the sinuses were performed with a tomographic rotating gamma camera. To determine the sensitivity of the technique, the nose and the maxillary sinuses of cadaver heads were painted with varying amounts of Tc99m and then similarly scanned. RESULTS Scans of the cadaver heads showed clear resolution between the nasal cavity and the maxillary sinus. It was determined that 20 microci was the smallest amount of Tc99m that could be resolved to be in the sinuses. Scans of subjects showed intense activity in the nasal cavity but none in the paranasal sinuses despite the delivery of a supraphysiologic dose of Tc99m ragweed pollen. CONCLUSION Inhaled ragweed pollen does not appear to enter the paranasal sinuses. It is unlikely that an inhaled antigen-IgE antibody reaction occurs in the sinus mucosa.

Mechanism of hepatic extraction of gelatinized 99mTechnetium sulfur colloid

Hepatic extraction, cellular and subcellular localization of gelatin stabilized Tc-99m sulfur colloid was studied in the rat model with time sequenced microautoradiography from 15 min to 24 h following I.V. administration of the tracer. Hepatic lobular and cellular distribution, quality and quantity of focal grain pattern, grain clusters, remained essentially constant for the period of study. Grain clusters were associated predominantly with Kupffer cells lining the peripheral segment of hepatic lobular sinusoids. Subcellular localization of gelatinized Tc sulfur colloid, stained prior to the I.V. administration with osmium tetroxide, was demonstrated with a transmission electron microscope in unosmicated liver tissue. Extracted Tc sulfur colloid particles were attached in groups to cytoplasmatic membranous intrasinusoidal projections of activated Kupffer cells. Intracytoplasmatic phagocytosis was not demonstrated. The kinetic arrest and en groupe extraction of Tc sulfur colloid particles at the Kupffer cell membrane suggests a specific membrane receptor site and specific Tc sulfur colloid particle-plasma protein interaction at the time of extraction. Hepatic extraction of gelatinized Tc sulfur colloid thus reflects primarily extra and intra hepatic hemodynamics and does not serve as an indicator of phagocytic hepatic reticuloendothelial system function.

Tropolone: A Lipid Solubilizing Agent for Cationic Metals

Lipid soluble agents which chelate radioactive cations have several potential uses in nuclear medicine including: brain imaging, labeling of blood elements, and identifying fatty infiltration of organs. A tropolone-gallium complex has been characterized by the determination of in vitro partition ratios correlated with in vivo organ distribution in the rat. Partition ratios were determined for gallium-67 citrate, indium-114m chloride, and iron-59 chloride cations complexed with tropolone in chloroform+water, octanol+water, olive oil+water, and olive oil+plasma two-phased systems. Tropolone proved to be highly effective in the lipid solubilization of these metal cations. Distribution studies in animals of these cations complexed with tropolone demonstrated an increased concentration of these cation complexes in tissues of high lipid content when compared with appropriate controls.

Evidence of large particle allergen inhalation from contact with surfaces

BACKGROUND To establish a more accurate relationship between dust mite allergen on surfaces such as bedding with respiratory uptake, an exposure method is needed which correlates exposure of allergen on surfaces with respiratory dose. OBJECTIVES Assess if aerodynamically large allergen particles (> 10 microm), similar in nature to dust mite allergen, is inhaled into the nose from direct head-and-hand contact with allergen contaminated surfaces. METHODS Short ragweed pollen (20-microm diameter) was used as a surrogate for dust mite allergen exposure because of its similar aerodynamic and physiologic properties. Pillows and a section of linoleum (followed by a hand press) were embedded with 99MTechnetium labeled pollen. Particles on the linoleum were transferred to the sampler after a hand press to the surface. Simulated human exposure was performed by surface-sampling particles, at a capture velocity of the nose, onto a filter. Human evaluation of hand transfer to the nose or direct inhalation from a pillow was performed with three subjects. Percentage respiratory uptake and deposition location was determined by gamma camera imaging. RESULTS Simulated respiratory uptake of pollen by hand-to-nose transfer and directly off pillows was 20% and 1.4%, respectively. Human subject respiratory uptake by hand-to-nose transfer and directly off pillows was 6.6% and 1.5%, respectively. Most of the regional activity was found immediately in the nasal vestibule with 13% to 39% of the total activity localized in the pharyngeal region. CONCLUSIONS Aerodynamically large allergen particles (pollen) are inhaled and deposited into the anterior nose and pharyngeal areas of the respiratory tract from direct contact with allergen-containing surfaces.

Layout and Planning of a University Hospital Clinical Cyclotron/PET Facility

This paper describes the layout and planning of one of the most space efficient clinical PET centers built to date. It occupies 2250 square feet (NSF) of space. The RDS 112 self-shielded cyclotron and the chiller unit occupy about 650 NSF while the PET imaging section, containing the scanner room, ECAT control and computer rooms, receptionist office space, two patient preparation rooms, scan reading room and a break room occupy a total of 1010 NSF. Radiochemistry/pharmacy has only 590 NSF which includes office spaces for chemist, pharmacist, trainees and computers for cyclotron operation and patient management. The principal challenge was to build the radiochemistry facility in less than 300 NSF while remaining in compliance with OSHA, FDA and radiation safety regulations. This space is now occupied by two hot cells, a laminar flow hood for sterile preparation and pyrogen testing, a fume hood for dose drawing and HPLC/TLC preparation area, a radio-TLC scanner, two radio-HPLC and one radio-GC stations, a balance, an oven, a refrigerator, a dishwasher and a double sink with a DI water setup. We have been operating the facility since April, 1992 and are routinely producing 150–200 mCi of 18FDG and 20–25 mCi of 13NH3 with 98+ percent radiochemical purity and zero pyrogen level. In a typical production day the radiation levels vary from 0.1 to 2 mR/hr. The advantages and disadvantages of the layout are discussed.

Significance of diffuse cardiac activity on In-111 labeled leucocyte scans

To assess the significance of diffuse cardiac activity (DCA) seen on In-111 labeled leukocyte scans, we reviewed 87 studies performed over the last 4 years. Inflammatory cardiac conditions were seen as frequently in patients with DCA (15%) as those without (7%, P=0.3). There was a higher ratio of RBC:WBC in the final WBC preparation in the false-positive DCA group than the true positive DCA and no DCA groups. False-positive studies showing DCA are most likely due to residual blood pool activity.

An ultrafiltration technique for labeling red blood cells with Tc-99m.

This method automates the preparation of autologous Tc-99m labeled red blood cells utilizing the Amicon on-line column eluate concentrator to separate the plasma from the red blood cells. The red blood cells were pre-tinned with stannous diphosphonate and continuously recirculated over a 0.6 μ filter until all of the plasma was removed and the red blood cells remained suspended in a solution of 0.9% sodium chloride. Once the plasma has been removed the red blood cells are incubated with Tc-99m pertechnetate. The above Tc-99m red blood cells were compared to Tc-99m red blood cells produced in a similar manner except that centrifugation was used to separate the red blood cells from the plasma. Both preparations had a tagging efficiency of 98% or greater and rat distribution studies demonstrate that both preparations are equally stable as an in vivo intravascular agent.