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During an 18-month oncogenicity study using rats, approximately 10% of the animals developed a form of respiratory distress very similar to that seen in the terminal stages of chronic respiratory disease, commonly associated with Mycoplasma pulmonis infection. Investigation of the lungs of the affected rats revealed not only that they did not have the consolidation usually associated with chronic respiratory disease, but they also appeared macroscopically normal. Further investigation of a number of cases revealed systemic intravascular thrombus formation of the type usually referred to as disseminated intravascular coagulation. Using an antiserum to fibrin we have demonstrated the presence of intravascular fibrin deposits in the lungs of the affected rats and have shown them to be the same as experimentally induced intravascular fibrin deposits induced in rat lungs by the administration of thrombin after blocking the fibrinolytic system. This is the first example of such a phenomenon being recorded in aging rats.

The relation between dyspnoea of presumed cardiac origin and disturbed left ventricular systolic function was studied in a group of 67 year old men from the general population of Gothenburg, Sweden. Forty two men with cardiac dyspnoea were identified and 45 controls were randomly selected from a screened cohort of 644 men. Dyspnoea was graded according to the World Health Organisation standard, and M mode echocardiography, carotid pulse tracing, an apex cardiogram, and phonocardiography were used to evaluate the grade of dyspnoea and its relation to systolic time intervals, left ventricular ejection indices, and wall stress. The dyspnoea grade was significantly related to the left ventricular end systolic dimension, to septal and posterior wall fractional thickening, and to ejection indices such as fractional shortening. The dyspnoea grade was also significantly correlated with the ratio of end systolic wall stress to end systolic volume index. There was a close relation between end systolic wall stress and mean velocity of circumferential fibre shortening adjusted for heart rate. This relation did not clearly show reduced inotropy in the dyspnoeic men. There was no relation between the degree of dyspnoea and the systolic time intervals. Among the systolic variables obtained by echocardiography the only abnormal finding in mild to moderate dyspnoea was an increased end systolic dimension. The grade of cardiac dyspnoea seemed to be related to the degree of systolic left ventricular dysfunction, which was considerably impaired in severe dyspnoea. In population studies left ventricular end systolic dimension and fractional shortening may provide sufficient information on systolic function without the need to assess variables that are independent of load.

To evaluate the efficacy of a mild anxiolytic, alprazolam, in relieving dyspnea, we conducted a randomized, placebo-controlled double-blind study on patients with chronic obstructive lung disease. Twenty-four patients had alprazolam (0.5 mg bid) or placebo administered for one week, followed by placebo for one week, then either placebo or alprazolam for the third week. Assessment tests were performed at the outset, end of the first and second weeks, and finally end of the third week. The parameters measured were: pulmonary function, exercise testing on a bicycle ergometer, and the distance covered in a 12 minute walk. Subjective sensations of dyspnea at rest and during guarded exercise, as well as subjective feelings of calmness or anxiety were also recorded. There was no difference in mechanical lung function, but the PO2 tended to decrease and PCO2 to increase after alprazolam administration. The maximum exercise level attained and the distance covered in the 12 minute walk was unchanged. The subjective perception of dyspnea was the same before and after alprazolam, at rest and during exercise. We conclude that alprazolam is not effective in relieving exercise dyspnea in patients with obstructive lung disease.

Although pneumonia virus of mice (PVM) is ubiquitous among rodent colonies in the United States, it has not been reported to cause clinically apparent disease in euthymic mice. However, PVM has been reported to cause respiratory disease and death in experimentally infected euthymic and athymic mice. A group of nu/nu mice, housed in quarantine in a Trexler-type isolator, had weight loss and dyspnea. Gross necropsy findings included cachexia and diffuse pulmonary edema or lobar consolidation. Histologically there was diffuse interstitial pneumonia. Electron microscopy revealed filamentous virions budding from plasma membranes, and immunohistochemical staining of lung tissue was positive for PVM antigen. PVM was isolated from affected lung tissue in BHK 21 cells and mouse antibody production tests resulted in seroconversion to PVM. Experimental inoculation of athymic mice with lung homogenate from spontaneously infected mice resulted in clinically apparent respiratory disease and histologic lung changes similar to those in naturally infected mice. Inoculation of athymic mice with infected BHK 21 cell culture fluid resulted in pneumonia which was qualitatively similar to, but less severe than, that observed in mice with spontaneous disease. These findings indicate that naturally occurring PVM infection in athymic mice may cause respiratory disease and wasting.

In order to develop a reproducible, quantifiable means of assessment of the clinical status of patients with idiopathic pulmonary fibrosis (IPF), a composite clinical-radiographic-physiologic (CRP) scoring system was devised, using 7 variables: dyspnea, chest radiograph, spirometry, lung volume, diffusion capacity, resting alveolar-arterial PO2, and exercise O2 saturation. To assess this scoring system, we examined the relationships between CRP scores and histopathologic findings, including a cellular pathology score composed of abnormalities deemed to be potentially reversible, a fibrotic pathology score based on abnormalities felt to be essentially irreversible, and an index of overall pathologic derangement (total pathology score), derived from the sum of the cellular and fibrotic scores. The initial CRP determination at the time of open lung biopsy correlated significantly with the total pathology score (r = 0.61, p less than 0.001). The CRP score determined after 6 months of corticosteroid therapy showed a significant correlation with the fibrotic pathology score present on open lung biopsy (r = 0.76, p less than 0.001). The change in CRP after 6 months of corticosteroid therapy tended to reflect the cellular histopathologic component of the open lung biopsy (r = -0.43, p less than 0.10). Moreover, in none of these relationships did any individual component of the CRP score correlate better with the respective histopathologic index than did the CRP score itself. These data suggest that this CRP score is useful for the estimation of the severity of underlying pathologic derangement and for the longitudinal quantitative assessment of clinical impairment in patients with IPF.