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Biomedical subjects

R Greene

Publications and source records attributed to R Greene.

At least 91 records · Page 5Linked to original sources
PubMed1991

Asbestos-related disease in public school custodians.

A cross-sectional prevalence study of 120 public school custodians was carried out. The purposes were 1) to investigate the prevalence of asbestos-related disease in a group of custodians at risk for asbestos exposure in public schools and 2) to determine the proportion with disease attributable to exposures in school buildings. Medical and occupational histories, flow-volume loops, and posterior-anterior, lateral, and anterior oblique (AO) chest radiographs were obtained. Single breath DLCO was measured and chest auscultation performed. Mean age of subjects was 57 years and mean duration of work as a custodian, 27 years. Fifty-seven (47.5%) had no known or likely exposure to asbestos outside of their work as a school custodian (NOE). Pleural plaques (PP) occurred in 40 (33%) of the total group and 12 (21%) of the group with NOE. Pulmonary restriction (FVC less than 80% predicted, FEV1/FVC% greater than or equal to 70) occurred in 22 (18%) of the total group and 10 (17%) of those with NOE. DLCO was lower in the group with restriction. Multivariate analysis revealed significant associations (p less than 0.05) between both PP and restriction and duration of asbestos exposure. AO radiographs increased PP detection by a factor of 1.9. Our results reveal PP prevalence in excess of background and pulmonary restriction in the study population, and indicate that PP are attributable to asbestos in schools. Findings with regard to pulmonary restriction need further investigation. Prudent management of asbestos in buildings is indicated for the prevention of related disease.

Adult↗
PubMed1991

Endoscopic thoracic sympathectomy: evaluation of pulsatile laser, non-pulsatile laser, and radiofrequency-generated thermocoagulation.

We describe a modified technique for percutaneous denervation of the thoracic sympathetic chain by laser to treat selected cases of sympathetic causalgia of the upper extremities. The technique involves transpleural ablation with laser under thoracoscopic guidance through the second or third intercostal space-anterior axillary line. We also compare four different modalities of endoscopic denervation: A xenon chloride excimer laser (308 nm, 35 mJ/pulse, 20 pulses/sec, 2.2 mm catheter tip), CO2 laser (14 W, CW, 2 mm spot size), Nd:YAG laser (88 W, CW, 3 mm spot size), and radiofrequency-generated thermocoagulation (3 W, CW, 2.1 mm catheter tip) by performing bilateral thoracic sympathectomy on 12 mongrel dogs (three dogs each). Criteria analyzed included duration of exposure, power density, total energy output, laser penetration and spread, gross morphology, and scanning electron microscopy (SEM) of the destroyed neural tissue. Total ablation of the inferior segment of the stellate ganglion and the T1-T2 nerve roots by excimer laser required 83 +/1 1 Joules over an exposure period of 118 seconds. Ablation by CO2 and Nd:YAG laser required 153 +/- 13 Joules and 554 +/- 47 Joules delivered over 11 and 6 seconds respectively. In contrast, ablation of the same volume of nerve tissue by RF required 810 +/- 50 Joules over 270 seconds. SEM evaluation revealed that excimer and CO2 laser lesions were narrower in configuration compared to RF and Nd:YAG lesions which showed more lateral spread. The actual depth of penetration per 1 second exposure was similar for Excimer and CO2 (1.5 mm) and RF (1.3 mm), but deeper for Nd:YAG (3 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Mediastinal abnormalities: detection with storage phosphor digital radiography.

Conventional film radiography (FR) and six postprocessing algorithms of isodose storage phosphor digital radiography (SR) (0.2-mm X 10-bit pixel matrix) were compared in the evaluation of 40 mediastinal and 30 pulmonary lesions in 60 patients who underwent computed tomography of the chest. The six SR algorithms varied among each other in only one image parameter. One algorithm approximated conventional image characteristics. The other five algorithms were designed to optimize imaging of the mediastinum and tested the effects of gray-scale reversal, adjustment of optical density, a linear instead of a sigmoid gradation curve, and moderate edge enhancement of high and medium spatial frequencies. Performance was evaluated by calculating the average area under the receiver operating characteristic curve (Az) of 5,040 observations by six readers. Post-processing with high-frequency edge enhancement and density optimization for the mediastinum significantly improved performance of SR over FR in the detection of mediastinal lesions (Az = .80 +/- .02 vs .73 +/- .01, respectively). Gray-scale reversal significantly decreased performance (Az = .64 +/- .03). All SR algorithms that were postprocessed to optimize imaging of the mediastinum were significantly inferior to FR in the detection of pulmonary lesions.

Algorithms↗
PubMed1991

Interstitial lung disease: impact of postprocessing in digital storage phosphor imaging.

The ability to resolve the fine linear structures of interstitial lung disease is one measure of the limiting performance characteristics of an imaging system. Conventional screen-film radiography was compared with six algorithms of isodose storage phosphor digital radiography (0.2-mm x 10-bit pixel matrix) in the detection of interstitial lung abnormality documented by means of computed tomography in 40 patients with abnormalities and 25 healthy control subjects. Performance was evaluated with an analysis of variance (the Fisher paired comparison test; P less than .05) of the average receiver operating characteristic area of 2,730 observations by six readers. The moderately and the more markedly high-frequency edge-enhanced algorithms of storage phosphor digital radiographs were equivalent in performance to screen-film radiography. The default mode, low- and medium-frequency edge-enhanced algorithms, and gray scale reversed mode of storage phosphor digital radiography were inferior to screen-film radiography. The authors conclude that high-frequency edge-enhanced algorithms can perform as well as screen-film radiography in the detection of interstitial disease.

Algorithms↗
PubMed1991

Coronary vasoconstriction induced by vasopressin. Production of myocardial ischemia in dogs by constriction of nondiseased small vessels.

BACKGROUND: We studied the effect of intracoronary administration of arginine-8-vasopressin on blood flow in nondiseased coronary arteries and determined whether this vasoconstriction was severe enough to produce ischemia in 30 dogs. METHODS AND RESULTS: In group 1 (n = 6), after vasopressin administration coronary blood flow was decreased by 41% (p less than 0.002) without changes in heart rate or aortic pressure, and left ventricular ejection fraction measured by radionuclide angiocardiography was decreased by 18% (p less than 0.0005). In group 2 (n = 6), ischemia was confirmed by measurement of transmural pH changes. Administration of vasopressin decreased subendocardial pH of the infused zone from 7.40 +/- 0.03 to 7.31 +/- 0.07 (p less than 0.01). The subendocardial pH of the zone not infused with vasopressin did not change. To overcome the intrinsic regulation of blood flow, operating primarily in small coronary arteries, we hypothesized that vasopressin must increase resistance primarily in large rather than small coronary arteries. After intracoronary infusion in group 3 (n = 6), however, most (94%) of the increase in resistance during vasopressin administration was explained by an increase of resistance in small coronary arteries. In group 4 (n = 9), vasopressin decreased coronary blood flow by 50% and decreased local shortening by 90% at a time when systemic hemodynamics were unchanged. Coronary constriction induced by vasopressin, or the recovery from it, also was not altered by cyclooxygenase blockade. CONCLUSIONS: Thus, vasopressin produces myocardial ischemia by constricting small, nondiseased coronary arteries severely enough to overcome the competition from normal coronary regulation, and this ischemic event is not mediated by prostaglandin products.

Animals↗
PubMed1991

Bilateral reexpansion pulmonary edema following unilateral pleurocentesis.

Acute ipsilateral pulmonary edema following reexpansion of the lung after pleurocentesis or pneumothorax is a well described entity. We report the unusual occurrence of bilateral pulmonary edema following unilateral pleurocentesis in a young male without heart disease. Various hypotheses regarding the mechanism of reexpansion pulmonary edema include increased capillary permeability due to hypoxic injury, decreased surfactant production, altered pulmonary perfusion and mechanical stretching of membranes. This case suggests that forces leading to ipsilateral reexpansion pulmonary edema also affect the contralateral lung.

Acute Disease↗
PubMed1991

Detection of bullous lung disease: conventional radiography vs digital storage phosphor radiography.

The detection of fine linear contours and altered aeration are requirements for the radiologic diagnosis of bullous lung disease and are severe measures of the spatial and contrast resolution of chest imaging systems. We compared plain film radiography with five postprocessing algorithms of storage phosphor digital radiography (2144 x 1744 x 10 bit matrix with 0.2-mm pixel size) in the detection of CT-proved bullous lung disease (35 patients and 25 normal control subjects). Receiver-operating-characteristic analysis of 2160 observations by six interpreters was done to evaluate the observers' performance. By analysis of variance (p less than .05), we found that the default digital algorithm and the three edge-enhancing algorithms of high and medium frequencies performed less well than plain films did, but the differences fell short of statistical significance. Gray-scale reversal was the only digital algorithm that performed significantly less well than plain films did. We conclude that any differences between digital algorithms and plain films in the detection of bullous lung disease were too small to be detected in this study. Any difference between the two methods in providing clinically important, diagnostic information is likely to be insignificant.

Algorithms↗
PubMed1991

Contribution of the bronchial circulation to lung preservation.

Short preservation time still severely limits lung transplantation. To determine the effect of bronchial arterial flush preservation, we studied 54 dogs using the isolated perfused working lung model. After baseline measurements, lungs were flushed with lactated Ringer's solution (60 ml/kg at 8 degrees C) by one of three methods: pulmonary artery perfusion, bronchial artery perfusion through a 15 cm closed aortic segment, or simultaneous pulmonary-bronchial artery perfusion. These groups were further subdivided and tested after 0, 4, and 17 hours of storage at 4 degrees C (n = 6 each). Lungs were ventilated (flow rate 140 ml/kg/min; inspired oxygen fraction 0.21) and continuously reperfused with normothermic deoxygenated autologous blood in a closed loop. Measured variables were hemodynamics, aerodynamics, and leukocytes in bronchoalveolar lavage. Survival time was determined from initial reperfusion to failure of the lung to oxygenate. After 0 and 4 hours of storage, there was no significant difference in survival times. After 17 hours, lungs subjected to pulmonary-bronchial artery perfusion survived longer than those perfused via either the pulmonary or bronchial arteries alone (120 +/- 24 versus 38 +/- 14 or 52 +/- 16 minutes; p less than 0.01). Pulmonary artery pressure and resistance in all groups except at failure were never different from baseline values in the intact animal. Shunts in the pulmonary-bronchial artery perfusion groups were closest to baseline at onset (8% +/- 4%) and remained lower throughout reperfusion than in the groups subjected to pulmonary or bronchial artery perfusion alone. After 17 hours, static compliance of pulmonary artery-perfused lungs was worse than baseline (1.1 +/- 0.2 x 10(-2) versus 3.2 +/- 0.7 x 10(-2) L/cm H2O/sec; p less than 0.05), whereas compliance in the pulmonary-bronchial artery perfusion groups remained constant (3.6 +/- 1.5 x 10(-2) L/cm H2O/sec). Elastic work performed by lungs subjected to pulmonary-bronchial artery flushing at onset was significantly lower when these lungs were reperfused immediately (201 +/- 14 versus 295 +/- 35 gm-m/min for pulmonary artery-flushed lungs) or after 4 hours of storage (229 +/- 30 versus 290 +/- 24 gm-m/min for pulmonary artery-flushed lungs). Bronchoalveolar lavage after 17 hours in the group subjected to pulmonary bronchial artery flushing demonstrated leukocyte counts similar to those of intact lungs (45 +/- 5 versus 29 +/- 8/mm3) and significantly less than in lungs subjected to pulmonary or bronchial artery flushing (137 +/- 18 or 82 +/- 10/mm3, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Hormone phage: an enrichment method for variant proteins with altered binding properties.

Human growth hormone (hGH), a 191 residue protein containing two disulfide bonds, was fused to the carboxyl-terminal domain of the gene III protein, a minor coat protein exposed at one end of the filamentous phage M13. The gene fusion was cloned into a plasmid containing origins of replication for Escherichia coli and filamentous phage and was packaged into phagemid particles upon infection by an M13KO7 helper phage. Transcription of the hGH-gene III fusion was controlled so that usually no more than one copy of the fusion protein was displayed along with the four copies of the wild-type gene III protein. The hGH-gene III fusion protein was properly folded, as judged by reactivity with six hGH monoclonal antibodies whose epitopes are sensitive to the folded conformation of hGH. Moreover, the hGH-gene III phagemid particles were enriched over 5000-fold from non-hGH phage, and 8-fold from a mutant hGH phagemid following a single hGH-specific elution step from hGH receptor-coated beads. The hGH phagemid should be useful for isolating new receptor binding mutants of hGH. More generally, this expression system may allow other large proteins with discontinuous binding epitopes to be displayed, and binding selections applied to their mutated gene III fusions on filamentous phage.

Base Sequence↗
PubMed1990

Aerodynamic evaluation of crystalloid and colloid flush perfusion for lung preservation.

To assess the effectiveness of pulmonary perfusion we evaluated the lung mechanics of 36 canine lungs in an isolated perfused working lung (IPWL) model. Four groups of lungs (n = 9 each) were preserved by pulmonary artery flushing with either high-potassium colloid (UW), high-potassium crystalloid (EuroCollins', EC), low-potassium crystalloid control (lactate), or low-potassium substrate-enhanced crystalloid (RPMI) followed by 130 +/- 10 min of cold storage. Ventilation remained constant (TV 10 ml/kg at 14 breaths/min with 5 cm H2O PEEP). Assessed data included lung resistance (R), timed expiratory volume (EV0.3 sec as %TV), lung compliance (C), elastic work (Wel), and flow-resistive work (Wres). Immediately following storage, R and Wel were similar for all groups (16 +/- 3 cm H2O/liter/sec and 149 +/- 18 gm/min). UW preserved lungs were less compliant (1.5 +/- 0.1 X 10(-2) liter/cm H2O) and required more inspiratory work (Wres 5.8 +/- 0.8 gm/min) compared to the low-potassium crystalloid (Lactate) group (2.0 +/- 0.1 X 10(-2) liter/cm H2O and 3.4 +/- 0.6 gm/min, respectively, P less than 0.05). For 3 hr of reperfusion, crystalloid lungs showed no significant change in R, C, Wel, or Wres. In contrast, R of the UW group increased significantly to 32 +/- 5 and 40 +/- 8 cmH2O/liter/sec at 1 and 3 hr, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Screening for asbestos-related pleural disease with digital storage phosphor radiography.

Digital storage phosphor radiography (SR) has a wide dynamic range and unique postprocessing capabilities that may improve the performance of screening studies for asbestos-related pleural disease compared with conventional film radiography (FR). In a group of 32 asbestos-exposed and nine control subjects with established pleural data, we compared the screening performance of FR and SR obtained with a single isoexposure, dual-energy technique (system resolution 0.2 mm, 10 bits). Performance was evaluated for 7320 observations by eight readers using a paired t test (P less than .02 with Bonferroni correction) of averaged receiver operating characteristic curve (ROC) areas (Az +/- standard error). We found that SR alone and SR supplemented by dual-energy soft-tissue and calcium images (SRde) were superior to FR in the overall detection of pleural abnormalities (Az = 0.90 +/- 0.01, 0.90 +/- 0.01, and 0.88 +/- 0.01, respectively). In the specific detection of pleural calcification, SRde was superior to FR (Az = 0.91 +/- 0.01 and 0.87 +/- 0.01, respectively; P less than 0.01). Analysis of variance indicated that SRde most closely reproduced an established pleural score based on the International Labor Organization (ILO) classification of the pneumoconioses (P less than 0.05, Scheffé's multiple comparison test). We conclude that isodose SR performs at least as well as FR in screening for asbestos-related pleural disease. SR supplemented by dual-energy images might improve the specific detection of pleural calcifications compared with FR.

Asbestosis↗
PubMed1990

Digital storage phosphor imaging versus conventional film radiography in CT-documented chest disease.

The advantages of imaging the chest with digital storage phosphor radiography (SR) may be nullified by its spatial resolution, which is lower than that of conventional film radiography (FR). To test the reader detection performance with the two modalities under clinical conditions, the authors compared 140-kVp isoexposure SR (system resolution: 0.2 mm, 10 bits) and FR images of a variety of chest abnormalities proved by computed tomography (CT) (157 patients, 244 abnormalities, 5,652 observations, six readers). In all tests, SR was as good as or better than FR (P less than .05). In overall detection, indicated by the average area of receiver operating characteristics, SR and FR were equivalent. SR was superior for mediastinal lesions and for pulmonary opacities greater than 2 cm in diameter. For all other types of pulmonary lesions and pleural abnormalities, SR and FR were equivalent. Currently available commercial SR systems can replace film radiographic systems in the detection of a wide variety of chest lesions. SR is likely to enable better visualization than FR in the detection of mediastinal and large pulmonary abnormalities.

Female↗
PubMed1990

Asbestos-related radiographic abnormalities in public school custodians.

A cross-sectional prevalence study of 120 public school custodians was carried out to investigate the prevalence of asbestos-related disease and to determine the proportion with disease attributable to asbestos exposures in school buildings. Medical and occupational histories, flow-volume loops, and posterior-anterior, lateral, and anterior oblique (AO) chest radiographs were obtained. Single breath DLCO was measured and chest auscultation performed. The present report describes radiographic abnormalities and associations with exposure. Mean age of subjects was 57 years and mean duration of work as a custodian, 27 years. Fifty-seven (47.5%) had no known or likely exposure to asbestos outside of their work as a school custodian (NOE). Pleural plaques (PP) occurred in 40 (33%) of the total group and 12 (21%) of the group with NOE. Multivariate analysis revealed significant associations (p less than 0.05) between PP and duration of asbestos exposure. The proportion with PP increased PP detection by a factor of 1.9. Our results reveal PP prevalence in excess of background in the study population and indicate that PP are attributable to asbestos exposure in schools in a subset with NOE. Prudent management of asbestos in buildings is indicated for the prevention of related disease.

Adult↗