Effect of high-frequency current on nerve and muscle tissue.
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Animals↗
Biomedical subjects
W T Miller
Publications and source records attributed to W T Miller.
Diffuse pulmonary hemorrhage: a review and classification.
Diffuse pulmonary hemorrhage is an uncommon condition that is difficult to differentiate radiographically from diffuse pneumonia or pulmonary edema. The diagnosis should be suspected when a patient has even mild hemoptysis or has one of the diseases known to be associated with diffuse pulmonary hemorrhage. This paper reviews the clinical and radiographic features of diffuse pulmonary hemorrhage and presents a classification scheme depicted as a Venn diagram formed by four overlapping circles representing pulmonary hemorrhage, renal disease, immune complex disease, and antiglomerular basement membrane (anti-GBM) disease. This scheme results in six categories of pulmonary hemorrhage: associated with glomerulonephritis and anti-GBM antibody; associated with renal disease without demonstrable immunologic abnormalities; associated with glomerulonephritis and immune complex disease; associated with immune complex disease without renal disease; associated with anti-GBM antibodies without renal disease; without associated immunologic or renal abnormality. Examples of these disorders are illustrated. Improved clinical-radiographic correlation may lead to earlier diagnosis and treatment of diffuse pulmonary hemorrhage and its causes.
Anemia↗
Expanding spectrum of pulmonary disease caused by nontuberculous mycobacteria.
The clinical and radiographic features of 35 patients with nontuberculous mycobacterial (NTMB) pulmonary infections were reviewed. Radiographs of half the patients showed the pattern of cavitary upper-lobe infiltrates typical of reactivation tuberculosis; those of the other half had a radiographic pattern characterized by patchy, nodular infiltrates without an upper-lobe prevalence. Approximately half of the latter group showed multiple small cavities resembling those seen in bronchiectasis. These results suggest that studies in which the diagnosis of NTMB infection has been made primarily from sputum cultures may have been biased toward detecting cavitary disease. The spectrum of pulmonary disease caused by NTMB appears to be larger than previously appreciated. An enhanced awareness of alternate presentations of NTMB infections may result in earlier diagnosis.
Adult↗
Invasive pulmonary aspergillosis and acute leukemia. Limitations in the diagnostic utility of the air crescent sign.
The air crescent sign is regarded as an important diagnostic finding in invasive pulmonary aspergillosis (IPA). This study examined the incidence, clinical importance, and natural history of air crescents in 25 patients with acute leukemia and IPA. Twelve (50%) of the patients had cavities (ten with an air crescent) that appeared an average of 15 days after the initial infiltrate. The diagnostic utility of the air crescent sign was relatively minor; cavities developed after the diagnosis was established in 50% of cases and after therapy was started in 75% of cases. In each case, the pneumonia improved at the time of cavitation. In six patients (50%), the cavities resolved over 2-8 months. Three patients (25%), however, experienced massive hemoptysis. Air crescent formation, previously shown to be dependent on granulocyte recovery, was associated with improved survival (67%) compared with the group without cavitation (8%). In the latter group, the pneumonia in ten (77%) of 13 patients progressed to diffuse disease. In patients with leukemia, the diagnostic value of the air crescent sign is limited by cavities that develop relatively late, as the infection improves after white blood cell recovery; cavities that do not occur in patients who remain neutropenic; and associated hemorrhage, at times life-threatening, that obscures the air crescent. The diagnosis of IPA should not await observation of air crescents in these patients.
Acute Disease↗
Pulmonary cavitation and massive hemoptysis in invasive pulmonary aspergillosis. Influence of bone marrow recovery in patients with acute leukemia.
The influence of bone marrow recovery on the clinical and radiographic course of invasive pulmonary aspergillosis in patients with acute leukemia has not been well characterized. We studied 26 patients with acute leukemia and invasive pulmonary aspergillosis, comparing those who recovered from chemotherapy-induced granulocytopenia (Group 1, 15 patients) with those who did not (Group 2, 11 patients). Radiographic evidence of pulmonary cavitation was not seen in any Group 2 patient, but developed in 11 of 15 (73%) Group 1 patients (p less than 0.005). In these patients, cavitation always occurred after marrow recovery, an average of 2.0 days (range: 0 to 6 days) after the granulocyte count exceeded 500/mm3. Eight patients in Group 1 and 2 in Group 2 experienced a total of 38 episodes of hemoptysis. Four of the 26 patients, all in Group 1, developed massive hemoptysis (greater than 150 ml of blood per episode), leading to 1 death. In 3 of these 4 patients, cavitation preceded the episode of massive hemoptysis. At the time of massive bleeding, the granulocyte count was greater than 500/mm3, the platelet count greater than 38,000/mm3, and the other coagulation parameters were normal in all 4 patients. Our findings demonstrate that in patients with acute leukemia undergoing chemotherapy, bone marrow recovery markedly influences the clinical and radiographic course of invasive pulmonary aspergillosis. Development of a granulocyte count greater than 500/mm3 is associated with pulmonary cavitation, and on occasion with massive hemoptysis.
Acute Disease↗
The troublesome nipple shadow.
In a review of 1000 routine chest examinations, the nipple of the male or female breast was visible about 10% of the time. In 14 instances (1.4%), the reviewing radiologist thought that uncertainty of identification warranted additional films. In four of these instances, the density proved to be something other than nipple. In all other instances when a nipple shadow was identified (8.9%), follow-up was not deemed necessary for various, often somewhat subjective reasons. Thus the frequency of erroneous identification of nipples could have been higher. Certainty of nipple identification would have involved considerable cost and inconvenience in repeat examinations. In another group of 500 patients, identification of the nipple with a lead marker on all patients eliminated uncertainty and the necessity for any repeat examinations. The patients placed low cost markers at the time of disrobing. Convenience and certainty were served by this simple maneuver.
Breast↗
Evaluation of the chest radiograph in the emergency department patient.
This article discusses the differential diagnosis of abnormal radiographic patterns most commonly seen in emergency department patients with chest disease. Conditions associated with trauma are also described.
Acquired Immunodeficiency Syndrome↗
Application of a human tumor colony-forming assay to new drug screening.
The applicability of a human tumor colony-forming assay to drug screening was investigated in terms of feasibility, validity, and potential for discovering new antitumor drugs. Feasibility was addressed in a pilot study during which basic methods, appropriate assay quality controls, and a standardized protocol for screening were developed. Considerable variability was noted in the availability and colony growth of different tumor types. The majority of the evaluable experiments utilized breast, colorectal, kidney, lung, melanoma, or ovarian tumors. For many tumor types, little evidence of growth was observed, or only rare specimens formed colonies. Colony-forming efficiencies ranged from 0.05 to 0.11% for the six most useful tumors listed above. A set of quality control measures was developed to address technical problems inherent in the assay. Testing of standard agents in the pilot study established that most of these agents could be detected as active. However, it also identified three assay limitations: compounds requiring systemic metabolic activation are inactive; medium constituents may block the activity of certain antimetabolites; and compounds without therapeutic efficacy may be positive in the assay. The assay categorized nontoxic clinically ineffective agents as true negatives with 97% accuracy. Of 79 compounds which were negative in the current National Cancer Institute prescreen (leukemia P388), 14 were active in the assay. Several demonstrated outstanding in vitro activity and are structurally unrelated to compounds already in development or in clinical trials. A subset of these active compounds were found to lack activity in a P388 in vitro colony-forming assay. This indication of differential cytotoxicity to human tumor cells makes this subset of compounds particularly interesting as antitumor drug leads. The demonstrated sensitivity to most standard agents, discrimination of nontoxic compounds, reproducibility of survival values within assays and between laboratories, and evidence of ability to identify active compounds which were negative in the in vivo prescreen suggest that the human tumor colony-forming assay may be a valuable tool for antitumor drug screening. However, because of technical limitations inherent in the current assay methodology, this must be confined to selected tumor types and limited to screening on a moderate scale.
Antineoplastic Agents↗
Pneumothorax as a complication of placement of a nasoenteric tube.
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Aged↗
Role of fiberoptic bronchoscopy in the diagnosis of invasive pulmonary aspergillosis in patients with acute leukemia.
The utility and safety of fiberoptic bronchoscopy in the diagnosis of invasive pulmonary aspergillosis in patients with acute leukemia have not been examined. The results of 21 bronchoscopic procedures in 19 patients with invasive pulmonary aspergillosis and acute leukemia were reviewed. Analysis was confined to the 16 patients who had histopathologically documented infection on biopsy or at autopsy. Fiberoptic bronchoscopy established or suggested the diagnosis of invasive pulmonary aspergillosis in eight of 16 (50 percent) patients. Transbronchial or bronchial biopsy added only one diagnosis to those obtained by bronchial washing and brushing. Although fiberoptic bronchoscopy was a safe and well-tolerated procedure in our patients with invasive pulmonary aspergillosis and acute leukemia, its success rate was only 50 percent overall, and it appeared to be even less successful when performed early in the course of the disease. Fiberoptic bronchoscopy is a useful first procedure for the evaluation of patients with acute leukemia and possible invasive pulmonary aspergillosis, but a negative result does not exclude aspergillosis. Further diagnostic procedures, including repeated bronchoscopy, or institution of empiric antifungal therapy may be warranted if the clinical suspicion of invasive pulmonary aspergillosis is high.
Acute Disease↗
An occupational therapist as a sexual health clinician in the management of spinal cord injuries.
The Sexual Health Clinician is a health care specialist who is able to assess the sexual potential of physically disabled persons and assist them in the development of acceptable alternatives in sexual practices. This specialty role was first developed at the Spinal Cord Injury Unit, Shaughnessy Hospital in Vancouver, B.C., Canada, to answer a need of spinal cord injured patients, their partners and family. The opportunity to join the Service arose in May, 1981 following one year as the Senior Occupational Therapist on the Spinal Cord Injury Unit. This paper, which describes the experience of an occupational therapist as a member of the Sexual Health Service, is presented in five brief parts: 1. a background history; 2. a description of the sexual problems of the spinal cord injured and the goals of rehabilitation in this area; 3. the role of the Sexual Health Clinician; 4. the strengths and limitations of Occupational Therapy in this new role; 5. a brief discussion of the the need for a sex-related role and curriculum for students of Occupational Therapy.
British Columbia↗
Application of ILO classification to a population without industrial exposure: findings to be differentiated from pneumoconiosis.
The International Labour Office (ILO) classification of radiographs of pneumoconiosis is a standard means of assessing the presence or absence of pneumoconiosis in workers exposed to mineral dusts. Using this classification, 200 admission chest radiographs were reviewed on hospitalized patients in an urban university medical center to determine the prevalence and possible significance of "small opacities" in a population without known industrial exposure. Seventy-one men and 129 women were screened with the mean age of 44.2 years (range, 15-84). Thirty-six (18%) of the 200 patients had small opacities at profusion level 1/0 or greater, and this constituted the "positive radiographs" group. Twenty-two patients (11%) with positive radiographs had no documentable dust exposure or other specific medical etiology that would explain the presence of their lung opacities. The high prevalence of small opacities in "normal" older individuals has important implications in the assessment of patients with suspected pneumoconiosis.
Adolescent↗
Radiographic evaluation of asbestos-related chest disorders.
This paper reviews the radiographic, clinical, pathologic, and epidemiological features of pleural and pulmonary parenchymal disorders which have been related to asbestos exposure. In particular, the following are discussed: (1) pleural plaques--radiographic detection by plain films and computed tomography, normal and abnormal densities which may mimic plaques, the 1980 ILO U/C classification, recent epidemiological data on plaques including their relationship to carcinoma and mesothelioma; (2) diffuse pleural thickening; (3) benign asbestos pleural effusions; (4) mesothelioma--emphasizing recent advances in diagnosis, staging, therapy, and prognosis; (5) parenchymal fibrosis--pathogenesis, relationship to fiber exposure, plaques, and carcinoma; (6) bronchogenic carcinoma; (7) rounded atelectasis--recent observations on its association with pleural thickening. A role of radiology in medicolegal aspects of asbestos-related disease is briefly examined.
Asbestos↗
Radiation-induced pneumothorax.
Pneumothorax is an uncommon complication of radiation therapy to the chest. The proposed pathogenesis is radiation-induced fibrosis promoting subpleural bleb formation that ruptures resulting in pneumothorax. We report on two young patients with primary sarcomas without pulmonary metastases who developed spontaneous pneumothorax after irradiation. Neither patient had antecedent radiographic evidence of pulmonary fibrosis.
Adolescent↗
A bidomain model for anisotropic cardiac muscle.
Cardiac muscle is considered to consist of an intracellular domain and an extracellular or interstitial domain. Current passes from one domain to the other through the cell membrane. Electric potentials in interstitial space are shown to be associated with current sources proportional to the spatial gradient of the cellular transmembrane action potential, phi m. Hence, given the distribution of phi m throughout the myocardium, one can calculate the surface electrocardiogram and extracorporeal magnetocardiogram. The problem is considerably complicated when anisotropy is considered. If interstitial space is approximately isotropic, however, the sources are still proportional to delta phi m. It is shown that the effects of intracellular anisotropy on the surface electrocardiogram may be relatively small. The inverse problem is discussed briefly, with consideration of the relationship of the magnetocardiogram to the electrocardiogram. Finally, it is shown that if the heart can be considered to be bounded by a closed surface, then the value of phi m on this surface is uniquely related to the surface electrocardiogram to within a constant, provided there are no internal discontinuities. Such discontinuities, however, would be expected to occur in cases of ischemia and necrosis.
Biomedical Engineering↗
Lung disease caused by amiodarone, a new antiarrythmic agent.
Amiodarone hydrochloride, used for prophylaxis of recurrent ventricular tachyarrhythmias that are resistant to other agents, may cause toxic pulmonary reactions associated with abnormal chest radiographs. The authors review four new cases of amiodarone-induced toxicity and eight cases reported in the literature. Peripheral areas of consolidation, predominantly in the upper lobes and resembling chronic eosinophilic pneumonia or tuberculosis, and diffuse interstitial disease were seen. Clinical symptoms included dyspnea on exertion, weakness, and occasionally pleuritic pain. Radiographic abnormalities developed after a median latency period of six months on the drug (600 to 800 mg daily). Pathologic findings suggested a possible toxic effect of the drug on phospholipid metabolism in the lung. Amiodarone toxicity may lead to significant pulmonary insufficiency. The clinical symptoms and radiographic abnormalities were completely reversible upon cessation of drug use and institution of corticosteroid treatment. Resolution generally occurs within three months.
Adult↗
Ventilator-induced subpleural air cysts: clinical, radiographic, and pathologic significance.
Alveolar rupture from the high airway pressures used in the treatment of adult respiratory distress syndrome may cause interstitial dissection of gas peripherally and the formation of "subpleural air cysts." These thin-walled, rounded air collections are easily detectable radiographically, and their recognition can provide an important early sign of pulmonary barotrauma. This report summarizes the clinical, radiographic, and pathologic features of this lesion in 5 adult patients. We found that tension pneumothorax rapidly occurs after the appearance of these cysts if airway pressures are not reduced or chest tubes are not in place. Secondary infection of the cysts was also common and added significant morbidity to this already compromised group of patients.
Adult↗
Active electric properties of cardiac muscle.
A model of electrical activity in the heart has been developed that treats the intracellular domain and the extracellular domain as electrical syncytia with anisotropic resistivities (bi-syncytial model). At the microscopic level, propagation is assumed to proceed primarily along the axes of individual cells. Considerations at the macroscopic level relate the transmembrane current to the intracellular and extracellular resistivity and the transmembrane potential. The result is a relationship between instantaneous extracellular potentials and cardiac action potentials.
Animals↗