Removal of infected transvenous pacemakers.
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Aged↗
Biomedical subjects
G E Miller
Publications and source records attributed to G E Miller.
Evaluation of a multiple disk centrifugal pump as an artificial ventricle.
A multiple-disk centrifugal pump based on the Tesla Turbine design has been modified for potential use as an artificial ventricle or ventricular assist device. The pump consists of a series of interconnected parallel disks placed within a spiral volute housing. This pump normally operates as a continuous flow device; however, a controller circuit has been developed to also allow for pulsatile operation. Frequency, systolic duration, systolic rise time, and diastolic decay time can be independently controlled to produce a wide range of pulsatile pressures and flows. This pumping system was tested in vitro on a mock circulatory system using a blood analogue. Inlet and outlet pressures, outlet flow, and motor rotations per minute were continually monitored over a wide range of physiologic operating conditions. The disk pump output was compared with that of other artificial ventricles and produced favorable results. Direct experimental comparisons were made with a Harvard Apparatus pulsatile piston pump. Unlike the Harvard pump, the disk pump does not use valves. Rather, a slight forward rotation of the disks is used to offset the adverse diastolic pressure gradient, which avoids backflow through the device.
Equipment Design↗
Physician payment reform: a bibliography.
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Medicare Assignment↗
RBRVS report: activities of the Ad Hoc Committee for Physicians' Reimbursement.
The Ad Hoc Committee to study the Resource-Based Relative Value Study has been active for more than 2 years. This Committee's membership was initially appointed by The Society for Thoracic Surgeons, but was quickly expanded so as to represent virtually all this nation's surgeons practicing the specialty of cardiothoracic and vascular surgery. This address describes the general activities of the Committee since its organization. It includes: 1. A brief description of the resource-based relative value scale (RBRVS). 2. The Committee's investigation of Harvard RBRVS Phase I as it relates to our specialty. 3. The Committee's findings and resultant testimony to the federal government and the American Medical Association. 4. The genesis and conduct of an independent study of the specialty. 5. A summary of our current position with respect to federal initiatives.
Relative Value Scales↗
Enhancement of social learning family interventions for childhood conduct disorder.
Social learning family intervention (SLFI) is the treatment of choice for young children exhibiting severe conduct disorder and antisocial behavior. Despite the reported success of this intervention, high levels of resistance, poor engagement, and inadequate maintenance of improvements are observed for a substantial proportion of distressed families. These obstacles have inspired enhancement efforts to improve basic social learning family-intervention models. The present review identifies promising approaches for maximizing treatment gains for the conduct-disordered child. Relevant studies were organized into 3 approaches: enhancements and expansions (a) within a dyadic (parent-child) interaction model, (b) within a broad-based model that acknowledges a wider range of family influences, and (c) through a multisystems model. SLFI enhancements within the dyadic model have centered on either the strengthening of parental skills already included in the SLFI regimen or the adding of new interactional strategies. Some gains, but only partial success, have been achieved with the dyadic model supplements. SLFI expansions from a broad-based model have focused on parental adjustment, parental expectations during treatment, and social-environmental stressors. The multisystems adjuncts to SLFI include cognitive-behavioral interventions to affect peer relations and ecological approaches to sweep across domains. The broad-based and multisystems expansions have produced promising but undertested treatment regimens. Related areas of investigation included therapy process research, medication combined with SLFI, and the involvement of fathers in treatment. Recommendations are offered for improvement of SLFI research. The apparent theoretical crossroads for SLFI treatment of childhood conduct disorder are discussed.
Antisocial Personality Disorder↗
The assessment of clinical skills/competence/performance.
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Clinical Competence↗
A multiple disk centrifugal pump as a blood flow device.
A multiple disk, shear force, valveless centrifugal pump was studied to determine its suitability as a blood flow device. A pulsatile version of the Tesla viscous flow turbine was designed by modifying the original steady flow pump concept to produce physiological pressures and flows with the aid of controlling circuitry. Pressures and flows from this pump were compared to a Harvard Apparatus pulsatile piston pump. Both pumps were connected to an artificial circulatory system. Frequency and systolic duration were varied over a range of physiological conditions for both pumps. The results indicated that the Tesla pump, operating in a pulsatile mode, is capable of producing physiologic pressures and flows similar to the Harvard pump and other pulsatile blood pumps.
Assisted Circulation↗
Picture versus question elaboration on young children's learning of sentences containing high- and low-probability content.
The main purpose of the two experiments reported here was to compare the potency of two types of elaboration on children's learning of sentence content: The effects of partial picture adjuncts were compared to the effects produced by answering "why"-questions about the relationships specified in the sentences. Five- to seven-year-old children heard sentences of the form, subject/verb/direct object/preposition/instrument. Sentences contained either a high-probability or a low-probability instrument given the semantic context. In Experiment 1, sentences either were accompanied by a partial picture depicting the sentence action but omitting the instrument or were presented without a partial picture accompaniment. Recall was improved by provision of partial pictures at study. In Experiment 2, the sentences were accompanied by complete pictures depicting the sentence content. In both experiments, questioning significantly reduced recall of high-probability sentences, with recall of instruments affected especially negatively. Evidence is presented that insufficient attention to instruments may have been one mechanism mediating depressed recall of high- compared to low-probability instruments in the questioned conditions. In summary, partial pictures improved cued recall of sentences in this study; in contrast, all significant effects produced by answering why-questions were negative ones (i.e., later recall was reduced following interrogation at study).
Attention↗
Role of psychiatrists in the public mental health system.
This paper examines the contributions of the psychiatric profession within the public mental health system. Following a discussion of the current status of psychiatry and the public mental health delivery system, the author outlines a number of key recommendations regarding the appropriate role of psychiatrists in public systems. The author emphasizes the importance of the public mental health system in all areas of psychiatric practice.
Community Mental Health Services↗
Fiscal incentives to development of services in the community.
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Community Mental Health Services↗
Continuing education. What it is and what it is not.
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Education, Medical, Continuing↗
Computer simulation of human mitral valve mechanics and motion.
The human mitral valve is the left atrio-ventricular valve which is composed of several components including leaflets, chordae tendineae, papillary muscles, and the valve annulus. Any or all of these components may fail and contribute to various valvular diseases including mitral regurgitation and mitral valve prolapse. A computer simulation of mitral valve mechanics and motion was written in BASIC for micro-computers. This program allows valvular geometry and biomechanical parameters to be varied and records time varying motion of the valve and all components during systole including a graphic display of the valve leaflets.
Chordae Tendineae↗
PULMONOLOGIST: a computer-based diagnosis system for pulmonary diseases.
PULMONOLOGIST is a prototype expert system designed as a decision-making aid for physicians in providing accurate diagnosis and treatment of lung diseases. Disease information in the system has been encoded in the form of rules and schemata. The system has been developed using the expert system building tool ART (Automated Reasoning Tool) from Inference Corporation. This paper gives a brief introduction to the expert system concept, and includes a detailed description of the diagnosis system. This system will be tested against clinical data in future studies.
Diagnosis, Computer-Assisted↗
Preoperative risk assessment in cardiac surgery: comparison of predicted and observed results.
In the present climate of quality-assurance policies, rigorous requirements for informed consent, and a constantly changing patient population, a system of preoperative risk assignment and postoperative correlation was developed to monitor and evaluate surgical performance. Patients were categorized by operation, priority (emergent, urgent, elective), New York Heart Association Functional Class, and risk. Risk was assigned before operation using data from the Coronary Artery Surgery Study (CASS) and the recent literature. Data were collected by a full-time data manager and were stored and analyzed by computer. From January 1, 1984, to July 1, 1985, 1,303 patients underwent operation for acquired disease. This group included 913 patients undergoing isolated primary coronary artery bypass grafting (CABG). The comparison of predicted and observed results showed: (Table: see text). For patients undergoing isolated primary CABG, the elective group had an operative mortality of 0.6% (2/329); the urgent group, 1.1% (5/450); and the emergent group, 5.2% (7/134). Preoperative risk assignment is an effective method of quality assurance. Female sex and age older than 60 years, which predicted an operative mortality of 2 to 5% in the CASS study and other recent series, did not predict a similar risk in our series.
Adult↗
The recovery of terminal lymph flow following occlusion.
The effects of external pressure on the relative terminal lymphatic flow rate following occlusion of the lymph system were studied. Sulfur colloid tagged with 99mTc was injected into the hind thigh of dogs prior to compressive loading. Initially, the lymphatic clearance of the tracer was measured for approximately forty minutes with no applied external pressure. The terminal lymph vessels were then occluded for thirty minutes with the application of an applied external pressure of 75 mm Hg. Finally, the lymphatic clearance following occlusion was measured with the application of a nonocclusive pressure. External pressures of 0, 30, and 45 mm Hg were tested to determine the effects of post-occlusive pressure application on terminal lymphatic clearance. Results indicated that terminal lymphatic clearance did not resume for an applied pressure of 45 mm Hg following occlusion. The relative lymphatic clearance rate at an external pressure of 30 mm Hg following occlusion was 54% of the clearance rate for a 0 mm Hg applied pressure prior to lymph occlusion. The results for a 0 mm Hg external pressure following occlusion indicated a 23 percent clearance rate compared to the pre-occlusive state. A two compartment model was utilized to determine the lymphatic clearance rate per unit tissue volume of subcutaneous tissue from the experimental data for each pressure phase.
Animals↗
An evaluation of case management.
This project explores the efficiency and effectiveness of case management as compared with the usual and customary services available to chronic mentally ill individuals in reducing readmissions to mental hospitals and improving the quality of life. A randomized pretest-posttest control group design was used to assign 417 individuals who had at least two discharges from a mental hospital to an experimental (E) group (N = 213) to receive case management services and a control (C) group (N = 204) who could receive any services but case management. After participation in the project for 12 months, 138 members of the E group and 126 members of the C group were reinterviewed. The E group received more services, cost more to maintain, and were admitted to mental hospitals more often, but concomitant improvement in quality of life indicators was not evident. Alternative explanations for the findings are discussed.
Activities of Daily Living↗
Assessment of cortical and trabecular bone distribution in the beagle skeleton by neutron activation analysis.
The distribution of bone calcium between morphologically identifiable cortical and trabecular bone obtained by dissection and quantitated by neutron activation analysis (NAA) is described. The skeleton of a female beagle dog was dissected into approximately 400 pieces and assayed for 49Ca produced in the University of California, Irvine TRIGA reactor. For each of the skeletal sections, we give the initial weight of the alcohol-fixed tissue, which includes cortical bone, trabecular bone, marrow, and cartilage, and a final tissue weight after the marrow and trabecular bone have been dissected away; total section and cortical section calcium weights are reported. The level of detail is represented, for example, by the vertebrae, which were divided into three parts (body, spine, and transverse processes) and by the long bones, which were divided into 10-12 parts such that characterization of the epiphysis, metaphysis, and diaphysis was accomplished. The median percentage cortical calcium values for cervical, thoracic, and lumbar vertebrae were 82%, 56%, and 66%, respectively; however, variation within these groups and among individual vertebral sections was about a factor of 2. For long bones, the median percentage cortical calcium varied from 90-100% in the midshaft to below 50% in the proximal and distal sections. The final calculated cortical tissue-to-calcium mass ratio (TCR) varied from about 4.5 for midshafts of the long bones to about 9 for thoracic vertebral bodies and indicated that the mineral fraction of cortical bone is not constant throughout the skeleton. The ratio of cortical to trabecular calcium in the skeleton was 79.6:20.4.
Activation Analysis↗
Mutagen activation of 1,2-dibromo-3-chloropropane by cytosolic glutathione S-transferases and microsomal enzymes.
It is not clear whether glutathione (GSH) conjugation to 1,2-dibromo-3-chloropropane (DBCP) results in genotoxic activation. Therefore S9, cytosolic, and microsomal fractions from uninduced rat liver were evaluated for their relative ability to activate DBCP in a modified Ames system. The S9 enzymes, either alone or in combination with exogenous GSH, did not enhance the mutagenicity of DBCP; identical results were obtained with cytosolic enzymes. Significant mutagenic activation of DBCP was produced by either S9 or microsomal fractions in the presence of NADPH. Activation was proportional to cytochrome P-450 concentrations, and was diminished by exogenous GSH. The protection against genotoxicity exerted by GSH did not require cytosolic glutathione S-transferases (GST). Thus, mutagenic activation of DBCP as obtained with S9 fractions is primarily due to biotransformation by microsomal rather than by cytosolic enzymes. Kinetic studies of cytosol-catalyzed conjugation of GSH to DBCP revealed tissue-specific differences in apparent Km and Vmax. Renal and testicular GSTs were associated with 28-46% smaller Vmax values when compared to hepatic GSTs (31.2 +/- 1.9 nmol/min X mg protein). However, renal and testicular GSTs had relatively higher affinities for DBCP. Thus, extrahepatic tissues possess significant capacity to conjugate GSH to DBCP. DBCP-GSH conjugates may undergo enzymatic modification by extrahepatic peptidase and beta-lyase to yield other sulfur-containing moieties that perhaps mediate DBCP's extrahepatic toxicity.
Animals↗