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Biomedical subjects

G L Snider

Publications and source records attributed to G L Snider.

At least 199 records · Page 11Linked to original sources
PubMed1976

In vitro effects of elastase and collagenase on mechanical properties of hamster lungs.

A previous study of hamsters, 21 days after intratracheal treatment with pancreatic elastase, showed development of emphysema, shift of the volume-pressure curve up an to the left, with both air and saline filling, and increase in quasistatic lung compliance. There was also a striking increase in vital capacity and lung volume at transpulmonary pressure of 25 cm H2O (TLC25); however, 21 days after collagenase treatment, there was only a slight increase in TLC25. The lung volume changes were not consistent with the theory that the collagen fiber network is responsible for limiting distension of the lung. This report considers saline-filled volume-pressure curves studied in excised hamster lungs after incubation with endotracheally instilled pancreatic elastase or clostridial collagenase solutions. Fluid retained in the lungs after the first infusion-withdrawal cycle was significantly greater in lungs treated with elastase than in lungs treated with collagenase or in control lungs. Total fluid volume at full inflation was similar in the 3 groups. Chord compliance of lungs treated with collagenase was greater at high volume range than that in lungs treated with elastase or control lungs; chord compliance of elastase-treated lungs was higher at mid-volume range than that of collagenase-treated or control lungs. The results of these in vitro studies are consistent with the theory of independently functioning elastic and collagen fiber networks, with the latter limiting lung distensibility at high volumes, and the former providing great extensibility at low volumes. Events that are part of the repair process after elastase injury may result in a change in the orientation of collagen in alveolar tissue and appear to account for the differing effects of in vivo and in vitro elastase treatment on the static mechanical properties of the lungs.

Animals↗
PubMed1976

Elevated serum angiotensin I converting enzyme in sarcoidosis.

Serum angiotensin I converting enzyme was found to be elevated in 56 patients with sarcoidosis (52.7 +/- 25.4 nmole per min per ml) compared to 84 normal control subjects (28.2 +/- 11.3 nmole per min per ml), 22 patients with tuberculosis (26.4 +/- 10.9 nmole per min per ml), and 20 patients with lymphomas (31.8 +/ 13.9 nmole per min per ml). Forty-eight per cent of the patients with sarcoidosis had values of enzymatic activity that were higher than 2 SD above the mean value of the control population; the false-positive rate in all nonsarcoidosis subjects combined was 5.5 per cent. Patients with parenchymal disease with or without hilar adenopathy had values somewhat higher than those with hilar adenopathy alone, but the difference was not significant (P less than 0.1). Patients with a known duration of disease greater than 2 years also had somewhat higher values than those with known disease less than 2 years, but the difference was not significant (P less than 0.1). There was no significant difference in values for patients receiving or not receiving steroids.

Humans↗
PubMed1975

Limited form of Wegener granulomatosis. Eye involvement as a major sign.

Bilateral uveitis was the initial manifestation of a limited form of Wegener granulomatosis in a 47-year-old man. Diagnosis was established by biopsy of a pulmonary nodule. Subsequently, evidence of lesions developed in the patient's central and peripheral nervous systems, but renal lesions were absent. Pulmonary lesions regressed on therapy with azathioprine and prednisone. Blindness ultimately resulted from retinal phlebitis, vitreous hemorrhages, and neovascular glaucoma.

Azathioprine↗
PubMed1975

The pathology of elastase-induced panacinar emphysema in hamsters.

A single dose of crystalline, porcine pancreatic elastase injected intratracheally into hamsters induces widespread alveolar enlargement with subpleural bullae. A uniformly severe lesion is consistently induced by 0-2 mg elastase per 100 g body weight and with negligible mortality. Compared with controls, which showed no lesion, elastase-damaged lungs show a highly significant (P less than or equal to 0-001) increase in alveolar size and a decrease in internal surface area. Taken with the associated physiological abnormalities, these findings closely simulate human emphysema of the panlobular (panacinar) type. Histologically it appears that elastase converts the fine elastic fibres in alveolar walls and pleura into thickened, nodular fibres which may also be broken along their length. With higher doses of elastase, i.e., 0-5 mg/100 g body weight, many pulmonary arteries showed segmental loss of inner and outer elastic laminae, usually with thrombosis on the overlying endothelium. The mechanism of this thrombosis is unclear. These experiments suggest that damage to elastic fibres may be an important element in the development of human panacinar emphysema, and that the damage could be one pathogenetic mechanism which produces damage of elastic fibres.

Animals↗
PubMed1975

Arterial blood gases and pH during sleep in chronic obstructive pulmonary disease.

Arterial blood gases were measured during 7 hours of sleep in 15 patients with severe stable chronic obstructive pulmonary discrease (COPD); 6 awake patients with COPD studies in recumbency for an average of 5 hours served as controls. Mean maximal decrease in arterial oxygen partial pressure (PaO2) (plus or minus SD) was 13.5 plus or minus 3.9 mm Hg for sleeping patients (p less than 0.005) and 5.5 plus or minus 1.7 mm Hg for controls (p less than 0.1), respectively. Changes in pH during sleep were of the magnitude expected with acute changes in arterial carbon dioxide partial pressure (PaCO2) in patients with chronic hypercapnia. Consistent changes in heart rate, respiratory frequency or cardiac rhythm were not observed during sleep. Nocturnal worsening of hypoxemia could be explained by alveolar hypoventilation in six sleeping patients and in five controls; in nine sleeping patients, further impariment of ventilation-perfusion mismatch also contributed to worsening of hypoxemia. There was no relationship between the decrease in PaO2 during sleep and the degree of airways obstruction or the PaO2 level when awake. Because of low PaO2, when awake, a fall in PaO2 during sleep brings values into the steep part of the oxyhemoglobin dissociation curve where slight changes in PaO2 result in marked changes in oxygen content. All patients with COPD whose waking PaO2 was below 60 mm Hg had PaO2 below 50 mm Hg during sleep; nocturnal oxygen therapy should be considered in such patients, particularly in the presence of polycythemia or troublesome right-sided heart failure.

Adult↗
PubMed1975

Fever and pneumonia after flexible fiberoptic bronchoscopy.

The frequencies of fever, parenchymal infiltration, and bacteremia were studied prospectively after 100 flexible fiberoptic bronchoscopies performed transnasally under topical anesthesia. Fever occurred after 16 per cent, and parenchymal infiltration, after 6 per cent of the procedures. Most complications were mild and transient; however, one patient developed rapidly progressive pneumonia and died. No organisms were isolated from cultures of blood drawn at the time of the procedure or during complications. The organisms most commonly isolated from the sputum of the patients who developed pneumonia were the aerobic and anaerobic bacteria normally found in the mouth. Isolation of a significant pathogen before the procedure did not predispose to development of a complication. Advanced age (greater than 60 years) and the endoscopic findings of abnormalities were significant predisposing factors. Bronchial brushing, but not bronchial biopsy or bronchial washing, was associated with significantly higher complication rates in patients with bronchial carcinomas than in those without a neoplasm. The mechanism of the fever and parenchymal infiltration is thought to be related to obstructive atelectasis and infection produced by organisms present in the airways at the time of the procedures.

Adult↗
PubMed1975

Cellular proliferation induced in the lung by cadmium aerosol.

Rats were exposed to a polydispersed aerosol of 0.1 per cent cadmium chloride in physiologic saline for a single period of 2 hours, and the evolution of damage was followed for a 10-day period. Control animals were unexposed rats and rats exposed to an aerosol of physiologic saline. Wet lung weight doubled by the fourth day in animals exposed to cadmium chloride, but not in the control groups. Apart from a transient increase in fluid content at 1 day, there was no evidence that the lung weight gain was due to inflammatory edema. Uptake of [3H]thymidine markedly increased during the first four days after exposure to cadmium chloride. Light autoradiography showed that [3H]thymidine labeling occurred almost exclusively in Type II alveolar cells at 1 day: later, the label appeared in interstitial cells and cells lying free within alveoli. These changes correlated well (r=0.70) with the increase in deoxyribonucleic acid on the fourth day after exposure. Uptake of [3H]thymidine and deoxyribonucleic acid content in rats exposed to cadmium chloride showed a significant difference from the control groups (P less than 0.001). These experiments demonstrate that exposure to cadmium chloride aerosol evokes a wave of cellular proliferation in rat lung. This finding is of interest, because heavy industrial exposure to cadmium in humans is known to be associated with severe physiologic impairment and anatomic damage.

Aerosols↗
PubMed1975

Bronchial brushing through the flexible fiberoptic bronchoscope in the diagnosis of peripheral pulmonary lesions.

Bronchial brushing was performed concomitantly with transnasal flexible fiberoptic bronchoscopy in 44 patients with localized peripheral pulmonary lesions and absence of visible bronchial abnormality down to subsegmental level. Fluoroscopic confirmation of brush placement was obtained. A diagnosis of malignancy was made by bronchial brushing in 12 of 23 patients (52 percent) proved to have neoplasm, although diagnostic accuracy rose to six of seven patients (86 percent) in the final quarter of the study. There was no relationship between diagnostic accuracy and tumor location. Diagnostic accuracy was highest for squamous cell carcinoma, intermediate for adenocarcinoma, and lowest for undifferentiated carcinoma. A diagnosis of tuberculosis was made in two of 21 patients found not to have malignancy, and bronchial brushing was the only procedure to yield diagnostic material in these two patients. There were no false-positive cytologic examinations and no complications. Fluoroscopic control of placement of the bronchial brush passed through the fiberoptic bronchoscope allows a single, highyield, diagnostic procedure to be performed with minimal risk to the patient. In selected cases, thoracotomy may be avoided by this procedure.

Adenocarcinoma↗
PubMed1975

Prolonged rate of decay of arterial PO2 following oxygen breathing in chronic airways obstruction.

Nine patients with moderate to severe chronic obstructive lung disease were grouped according to results of pulmonary function testing. After a short period of 100 percent oxygen breathing, it took on the average 20 minutes (range--18 to 24 minutes) for their partial pressure of arterial oxygen to return to baseline levels. These data suggest that, after discontinuing supplemental oxygen in patients with chronic airways obstruction, more than 25 minutes should elapse if a blood gas measurement is to reflect with certainty conditions during room air breathing.

Aged↗
PubMed1973

Phonopneumography.

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Auscultation↗