[en] A modification of the standard absorption edge technique is shown to be useful for determining the energy of broadened X-ray lines such as are observed for the last transitions in pionic atoms where the broadening is due to the strong pion-nucleus interaction. The technique offers an alternative and independent means of energy calibration for K transitions in pionic helium, lithium, beryllium and boron, and hence can be used for determining the strong interaction shift for such pion-nucleus systems. (Auth.)

[en] A Tc-99m macroaggregated albumin (MAA) perfusion lung scan and a Tc-99m DTPA aerosol ventilation scan were performed for suspicion of pulmonary embolism (PE) in a patient who was ten weeks pregnant. There was considerable reluctance on the part of the obstetricians to permit this study. Standard MIRD dose estimates to the fetus were performed, which showed a maximum fetal exposure of about 50 mrem. It was concluded that the risk to mother and fetus from undiagnosed and untreated PE is much greater than the negligible risk to the fetus from the radiation exposure; fear of fetal radiation damage should not be a deterrent to performing these scans

[en] Neutron energy spectra from the exclusive pion capture reaction Ho(π, γxn)Dy are presented. Neutron time-of-flight data was collected in coincidence with nuclear gamma rays which identified the final nuclear state. Most of the ground state band levels up to 12⁺ in even-even Dy isotopes were included. These correspond to odd neutron multiplicities from 3 to 11. The spectra show significant changes with neutron multiplicity, exhibiting a sharp cut-off at characteristic energies. Structure in the high energy component of the spectra has been resolved for the first time, and its correlation to the population of high-spin states is observed. This discrete component is strongest in coincidence with the 8⁺ → 6⁺ transition in ¹⁶⁰Dy and ¹⁵⁸Dy (neutron multiplicities 5 and 7). The capture reaction preferentially populates the 4⁺ and 6⁺ states in the ground state bands of ¹⁶⁰Dy and ¹⁶²Dy, corresponding to neutron multiplicities 5 and 3

[en] Because infection with Pheumocystis carinii pneumonia (PCP) causes alteration of the type I epithelial cells as the primary event, the authors studied patients with PCP to determine if PCP causes rapid clearance of Tc-99m DTPA. Twenty normal non-smoking subjects and 7 non-smoking patients with histologically proven PCP were studied. Serial studies were obtained in three patients. Following a two-minute inhalation of 1.6 μm aerosol particles of Tc-99m DTPA in saline, the activity over three peripheral regions of interest (ROI) of each lung was monitored for the next 7 minutes. The rate of decline of activity over each ROI was expressed as per cent decline/min. In 7 patients with PCP, the average clearance was 7.5 +- 3.6% min., normal, 1.3 +- 0.6% min.(SD). Three patients studied from 5 to 38 days following therapy had improvement in the rate of clearance. This has been demonstrated to be persistent even after clinical recovery of the patient. The ability to quantitate injury to the pulmonary epithelium may directly reflect the ability of Pneumocystis carinii to invade the lung. The authors conclude that Tc-99m DTPA clearance may be a useful test to help diagnosis and monitor the activity of PCP infections

[en] The neutron spectrum resulting from μ^--capture in ¹⁶⁵Ho has been measured with a time-of-flight spectrometer. For the first time a 13 MeV peak, and a break in the slope at 40 MeV is reported. The slope from 20 to 40 MeV is 8.88 +- 1^- MeV. This represents the first measurement of the neutron spectra by a system capable of resolving neutron energies near the muon mass. Neutron spectra from final nuclear states roughly identified by NaI pulse height are presented. A photon spectrum measured by Ge(Li) detectors exhibits neutron multiplicities up to 5 with an intensity greater than expected

[en] The regional clearance of /sup 99m/Tc-diethylenetriamine penta-acetate from the lungs was measured in 14 patients with noncardiogenic pulmonary edema, six patients with acute pulmonary edema secondary to heart failure, and 29 normal subjects. The radionuclide was delivered in an aerosol which was inhaled for 120 seconds, and the subsequent decline of radioactivity from the lungs was monitored for seven minutes over each of six peripheral regions of interest with a computerized scintillation camera. The average /sup 99m/Tc-DTPA clearance of these regions was accelerated above the 98 percent confidence limits in all but three of the patients with noncardiogenic edema. The mean clearance value in this group of patients was significantly greater than those in normal subjects or patients with cardiogenic pulmonary edema. Clearances returned toward normal in each of seven subjects who improved clinically. Only one of the patients with cardiogenic pulmonary edema had an elevated average clearance rate, and the mean clearance for this population was not statistically greater than normal. This procedure appears to detect increased epithelial permeability caused by lung injury and may help distinguish between cardiogenic and noncardiogenic pulmonary edema

[en] In situ and isolated fluid-filled rabbit lungs were used to study the transport of indicators between the air space and vascular compartments. These indicators were placed in either the perfusate or air spaces and samples were collected from the perfusate at intervals during a 1-h perfusion period. At the end of the hour, fluid was pumped out of the air space compartment into serial tubes and indicator concentrations were determined in both the air space and perfusion fluids. One hour after introducing the indicators into the air space, the relative decreases in solute concentration were (arranged from the greatest to the least decline): [¹⁴C]urea greater than ³⁶Cl^- = ¹²⁵I^- greater than ²²Na⁺ greater than [3H]mannitol. The relative rates at which the indicators appeared in the perfusate were similar. When the indicators were placed in the perfusate, a similar relationship was observed in the increase in air space concentrations, but the loss of ²²Na⁺ from the perfusate was similar to those of ³⁶Cl^- and ¹²⁵I^-. Losses of all indicators from the perfusate were two or more times those from the air spaces, and although the loss of [3H]mannitol from the perfusate was similar to that of ²²Na⁺ for about 30 min, subsequent loss was much slower. Very little ¹²⁵I-albumin traversed the tissue barrier, and the small changes in the concentrations of ¹²⁵I-albumin in the air spaces suggested that little fluid movement had occurred. These studies suggest that the epithelium is less permeable to solutes than the endothelium and permits passage of anions at a faster rate than ²²Na⁺

[en] Electron micrographic studies of lungs suggest that the epithelial cells are more tightly joined than the underlying endothelium, and macromolecules penetrate the endothelium more readily than the epithelium. Comparisons of epithelial and endothelial permeability to small molecules have been based upon the relative rates at which solutes traverse the alveolar-capillary barrier in fluid filled lungs and those at which they equilibrate across the capillaries in air-filled lungs. Because the former process is much slower than the latter, it has been concluded that the epithelium is less permeable to small solutes than the endothelium. However this difference may be related to inadequate access of solutes to airway surfaces. In this study, solute losses from the vascular space were compared to those from the airspace in perfused, fluid-filled rabbit lungs. ³⁶Cl^- and ¹²⁵I^- were lost from air-spaces almost twice as rapidly as ²²Na⁺. In contrast, the endothelium is equally permeable to ²²Na⁺ and these anions. Loss of ³H-mannitol from the perfusate resembled that of ²²Na⁺ for about 30 minutes, after which diffusion of ³H-mannitol into the tissue nearly ceased. These observations suggest that the epithelium is more permselective than the endothelium. By resisting solute and water transport, the epithelium tends to prevent alveolar flooding and confines edema to the interstitium, where it is less likely to interfere with gas exchange

No abstract available

[en] The clearance of Tc99m-DTPA aerosols from the lung has been used to detect and quantitate alterations in the permeability of the pulmonary epithelium. Clearance of the radionuclide is accelerated by both chronic and acute injuries to the lung and by smoking. Several laboratories have reported that Tc99m-DTPA clearance from upper lobes exceeded that from lower lobes in upright subjects. To investigate this phenomenon further the authors studied subjects with simultaneous anterior and posterior cameras in upright and supine positions. In the upright position, clearance from both the anterior and posterior upper regions of interest (ROI's) exceeded the lower regions (-1.64 +- .42 S.D. vs. -0.75 +- .41, anterior, p < .05, n=6), -1.04 +- .23 vs. -0.50 +- .36, posterior. All units = %/min. This difference was not observed in the supine subjects. Clearance from the anterior chest exceeded that from the posterior chest in the supine subjects (-1.28 +- .45 vs. -0.05 +- 1.08) and a small increase in radio-activity was observed in at least one ROI of 5 of 6 subjects from the posterior camera. An increase in activity is likely to be secondary to labeling of blood pool, which would have greatest affect where pulmonary blood volume is largest. Computer processing of the entire lung without observer bias in ROI placement showed similar effects of posture over non-peripheral ROI's. Five subjects breathed on PEEP to cause airspace distention, causing clearance to double. Both dependency and airspace distention appear to influence clearance of aerosolized DTPA, the latter may occur by stretching of epithelial pores