[en] Given the high cure rate of patients with Hodgkin's disease, the complications related to therapy take on great significance. Mantle irradiation to the thorax is used in virtually all patients with early stage Hodgkin's disease. Prior studies of patients receiving mantle irradiation demonstrated short-term (up to 24 months) abnormalities of pulmonary function. In the present study, we prospectively studied 13 patients for up to 60 months after irradiation only with serial pulmonary function tests, arterial blood gas tests, diffusing capacity of carbon monoxide, chest radiographs, and ventilation-perfusion scans. No respiratory symptoms attributable to therapy were noted. Frequent radiographic changes (62%) were found consisting of apical fibrosis, paramediastinal fibrosis, or pleural thickening. Two patients developed an asymptomatic spontaneous pneumothorax that resolved with conservative management. Ventilation-perfusion scans often (73%) revealed decreased perfusion to the lung apices with associated ventilatory deficits in one-half of these patients. Patients with intrathoracic disease had decreased lung volumes prior to therapy, and lung volumes did not change following irradiation. Lung mechanics were normal throughout the study. Gas exchange at rest was normal in patients with extrathoracic disease. Patients with intrathoracic disease often presented with an abnormal arterial PO2 and widened alveolar-arterial partial pressure gradient for oxygen. However, these parameters normalized by 9 months after therapy. Despite the frequent development of radiographic and V/Q scan abnormalities in the lung apices, patients tolerated mantle radiotherapy remarkably well. In fact, patients with intrathoracic disease demonstrated improved gas exchange at rest following therapy

[en] Normal structure and function of the lung parenchyma depend upon elastic fibers. Amorphous elastin is biochemically stable in vitro, and may provide a metabolically stable structural framework for the lung parenchyma. To test the metabolic stability of elastin in the normal human lung parenchyma, we have (a) estimated the time elapsed since the synthesis of the protein through measurement of aspartic acid racemization and (b) modeled the elastin turnover through measurement of the prevalence of nuclear weapons-related ¹⁴C. Elastin purified by a new technique from normal lung parenchyma was hydrolyzed; then the prevalences of D-aspartate and ¹⁴C were measured by gas chromatography and accelerator-mass spectrometry, respectively. D-aspartate increased linearly with age; Kasp (1.76 x 10^-3 yr^-1) was similar to that previously found for extraordinarily stable human tissues, indicating that the age of lung parenchymal elastin corresponded with the age of the subject. Radiocarbon prevalence data also were consistent with extraordinary metabolic stability of elastin; the calculated mean carbon residence time in elastin was 74 yr (95% confidence limits, 40-174 yr). These results indicate that airspace enlargement characteristic of 'aging lung' is not associated with appreciable new synthesis of lung parenchymal elastin. The present study provides the first tissue-specific evaluation of turnover of an extracellular matrix component in humans and underscores the potential importance of elastin for maintenance of normal lung structure. Most importantly, the present work provides a foundation for strategies to directly evaluate extracellular matrix injury and repair in diseases of lung (especially pulmonary emphysema), vascular tissue, and skin

[en] Tritium/³He measurements yield quantitative information on the age of young groundwater. Such measurements provide an important element in the use of groundwater flow systems as archives of environmental records. The general principles of tritium/³He dating of natural waters for this purpose are briefly discussed. This is followed by case studies in which tritium/³He dating is applied to groundwater flow systems of different complexity with respect to (1) the hydrogeological setting, (2) the presence of terrigenic helium (crustal and mantle sources) complicating separation of the tritiogenic ³He component and (3) the presence of tritium from sources other than natural production and (surface) tests of nuclear devices. The case studies include simple, sandy aquifers and more complicated sites such as fractured bedrock. They show that under most circumstances, tritium/³He data, if interpreted in the proper hydrogeological context, can provide reliable, quantitative age information. (author)