Biomedical subjects

J G Miller

Publications and source records attributed to J G Miller.

At least 109 records · Page 6Linked to original sources

PubMed1992

On mitigating professional arrogance in the treatment of sex offenders.

This article suggests that the adversarial approach of the criminal justice system towards handling of the paraphilias ultimately does more harm than good. The acceptance by helping professionals of the criminal justice model into their diagnostic consideration and treatment procedures is discussed, along with a discussion of some of the debilitating ethical and scientific implications of such an alignment. Historical, political and professional factors which have contributed to these disturbing trends are discussed and proposals are made as to how helping professionals might reclaim and reassert their traditional roles in service of their clientele.

Attitude↗

PubMed1991

A living systems analysis of organizational pathology.

Organizations have essentially the same subsystem processes as living systems at other levels. All of them adjust subsystem variables to changing environmental and internal circumstances. Pathology exists in any system when a subsystem variable remains out of its steady-state range for an extended period. The same classes of pathology can be found at all levels. This article analyzes the various forms of pathology that exist in living systems at the level of organizations and describes living systems process analysis. Studies of several types of organizations including U.S. Army battalions, a corporation, a hospital, and a possible space station or lunar base, are discussed.

Animals↗

PubMed1991

Ultrasonic backscatter tissue characterization in cardiac diagnosis.

Ultrasonic tissue characterization has shown the potential to yield information about structural and functional properties of cardiovascular tissue. The development of real-time two-dimensional integrated backscatter imaging has made feasible clinical investigations of ultrasonic tissue characterization, including detection of stunned myocardium in patients with acute ischemia, recognition of remote infarction, detection of cardiac allograft rejection, and study of diffuse myocardial involvement with systemic diseases such as diabetes mellitus. Technical improvements and scientific advances in the understanding of the interaction between ultrasound and tissue may open an even wider range of clinical applications. Even in its present, relatively preliminary form, tissue characterization appears to have the potential for clinical application. Additional clinical experience will stimulate refinements and increases in the diagnostic power of this promising approach.

Echocardiography↗

PubMed1991

Three-dimensional characterization of human ventricular myofiber architecture by ultrasonic backscatter.

Normal human left ventricular architecture comprises a highly aligned array of cardiac myofibers whose orientation depends on transmural location. This study was designed to determine whether measurement of integrated backscatter could be used detect the progressive transmural shift of myofiber alignment that occurs from epicardium to endocardium in human ventricular wall segments. Integrated backscatter was measured at 32 transmural levels in seven cylindrical biopsy specimens (1.4 cm diam) sampled from normal regions of six explanted fixed human hearts by insonification of samples at 180 independent angles in 2 degrees steps around their entire circumference with a 5-MHz broadband piezoelectric transducer. Histologic analysis was performed to determine fiber orientation. Integrated backscatter varied approximately as a sinusoidal function of the angle of insonification at each transmural level. Greater integrated backscatter was observed for insonification perpendicular as compared with parallel to fibers (difference = 14.5 +/- 0.6 dB). Ultrasonic analysis revealed a progressive transmural shift in fiber orientation of approximately 9.2 +/- 0.7 degrees/mm of tissue. Histologic analysis revealed a concordant shift in fiber orientation of 7.9 +/- 0.8 degrees/mm of tissue. Thus, human myocardium manifests anisotropy of ultrasonic scattering that may be useful for characterization of the intramural fiber alignment and overall three-dimensional organization of cardiac myofibers.

Heart Diseases↗

PubMed1990

The nature of living systems.

Living systems theory (LST) is concerned with eight levels of living systems, each of which is composed of 20 critical subsystems that carry out essential life processes. As a result of a continuous biosocial evolution involving progressive fray-out of components, the more recently developed levels in this hierarchy have become very complex. A brief summary of LST is presented in this article. Following this is a detailed analysis of current knowledge about the timer, which we have recently included in our list of subsystems.

Animals↗

PubMed1990

Myocardial ultrasonic backscatter for characterization of ischemia and reperfusion: relationship to wall motion.

We have previously shown that cardiac cycle-dependent variation of integrated backscatter occurs in normal myocardium. To determine whether myocardial ischemia and reperfusion can be distinguished by real-time integrated backscatter imaging we performed 10 min balloon occlusion of the Left Anterior Descending (LAD) coronary artery followed by reperfusion in 10 closed-chest anesthetized dogs. Images were obtained at baseline, during occlusion, and up to 120 min after reperfusion. We measured the magnitude and delay of cyclic variation of integrated backscatter in segments with and without asynergy. Radiolabeled microspheres were used to verify both ischemia and reperfusion. Ischemic segments exhibited decreased magnitude and increased normalized delay of cyclic variation of integrated backscatter (from 3.3 +/- 0.3 dB to 1.4 +/- 0.2 dB, mean +/- SE; and from 0.95 +/- 0.03 to 1.67 +/- 0.15, respectively, all p less than or equal to 0.001). Reperfusion promptly restored the magnitude of cyclic variation toward normal. However, the delay of the cyclic variation was restored only partially. Wall motion analysis of the ischemic sites revealed persistent abnormalities throughout the reperfusion interval despite return to normal of the magnitude and delay of cyclic variation. Thus, real-time integrated backscatter imaging permits detection and differentiation of changes in myocardial acoustic properties indicative of ischemia and of subsequent reperfusion.

Animals↗

PubMed1990

Perceptions of social responsibilities in India and in the United States: moral imperatives or personal decisions?

Indian and American adults' and children's (N = 400) moral reasoning about hypothetical situations in which an agent failed to help someone experiencing either life-threatening, moderately serious, or minor need was compared. For 1/3 of Ss, the agent's relationship to the needy other was portrayed as that of parent; for another 1/3, as that of best friend; for the rest, as that of stranger. Indians tended to regard the failure to aid another in moral terms in all conditions. In contrast, Americans tended to view it in moral terms only in life-threatening cases or in cases of parents responding to the moderately serious needs of their children. The results imply that Indian culture forwards a broader and more stringent view of social responsibilities than does American culture. Discussion centers on theoretical implications of the various cultural, need, role, and developmental effects observed.

Adult↗

PubMed1990

Anisotropy of the ultrasonic attenuation in soft tissues: measurements in vitro.

This study was designed to measure the ultrasonic attenuation within phantoms and tissue samples over a broad bandwidth and at many angles of incidence with respect to intrinsic orientations in order to elucidate both the frequency and angular dependence of the attenuation coefficient. Significant angular dependence, or anisotropy, of the attenuation was observed in canine myocardium (maximum to minimum ratio: 2.2 to 1) and a tissue mimicking phantom of oriented graphite fibers in gelatin (max to min: 2 to 1). In control studies, insignificant anisotropy was observed in the attenuation in canine liver samples and phantoms with graphite powder suspended in gelatin. Comparisons of the magnitude of variations of the oriented-fiber phantom to that predicted by a viscous relative motion model are presented.

Animals↗

PubMed1989

Cardiac cycle-dependent variation of integrated backscatter is not distorted by abnormal myocardial wall motion in human subjects with paradoxical septal motion.

To define the dependence of cardiac cycle-dependent variation of integrated backscatter on regional myocardial wall motion, 8 children mean age 10.6 +/- 1.3 y with congenital cardiac lesions associated with paradoxical septal motion were studied (study group). Six healthy children mean age 9.0 +/- 0.3 y with no history of cardiac disease served as controls (control group). Subjects in the study group had paradoxical septal motion but normal septal wall thickening detected by conventional two-dimensional and M-mode echocardiography. The control group had normal septal motion evident by conventional echocardiographic criteria. The percentage of systolic septal thickening was 46 +/- 4.5% and 42 +/- 5.9% in the study and control groups (p = NS). Cyclic variation was measured in parasternal long-axis views from several septal sites in each subject. Mean values of the magnitude of cyclic variation from independent septal sites were averaged to yield a regional average value for each subject. The average regional magnitude of cyclic variation was 8.3 +/- 1.0 dB and 5.7 +/- 0.4 dB in the study and control groups (p = NS). The results indicate that the measurement of cyclic variation of integrated backscatter is not distorted by altered regional wall motion, and that it reflects intrinsic contractile function.

Child↗

PubMed1989

Early identification with ultrasonic integrated backscatter of viable but stunned myocardium in dogs.

It has been shown that canine and human hearts exhibit a cardiac cycle-dependent variation of integrated backscatter (cyclic variation) that reflects intrinsic regional contractile performance. To determine whether ultrasound tissue characterization can identify viable though stunned myocardium before recovery of regional wall thickening, transient ischemic injury was produced in eight open chest dogs for 15 min followed by reperfusion for 2 h. Cyclic variation and wall thickening were measured before ischemia, at 15 min after the onset of ischemia and at selected intervals after the onset of reperfusion from multiple sites within the ischemic zone with a novel combined two-dimensional and M-mode acquisition system. Cyclic variation and wall thickening were computed from digitized M-mode integrated backscatter images with an algorithm developed and validated for this purpose. Magnitude and "delay" of cyclic variation and wall thickening were compared. Delay represents the degree of synchrony of regional cyclic variation or wall thickening with global ventricular mechanical systole. Baseline cyclic variation and wall thickening magnitudes were 3.8 +/- 0.2 dB and 37 +/- 1.4%, respectively. With ischemia, cyclic variation and wall thickening decreased to 1.7 +/- 0.2 dB and 17 +/- 2%, respectively (p less than 0.05, compared with baseline). Cyclic variation recovered to baseline levels within 20 min after reperfusion (3.3 +/- 0.4 dB, p = NS). Wall thickening remained depressed for 2 h after the onset of reperfusion (23 +/- 2%, p less than 0.05 compared with baseline). Delay of cyclic variation in a unitless ratio expressed as delay (in milliseconds) divided by the QT interval (in milliseconds) increased from 0.87 +/- 0.03 at baseline to 1.10 +/- 0.12 with ischemia, a change consistent with mild asynchrony, and returned to baseline (0.95 +/- 0.07, p = NS compared with baseline) within 20 min after reperfusion. Delay of wall thickening was 0.88 +/- 0.02 at baseline, increased to 1.23 +/- 0.09 with ischemia and remained significantly increased 2 h after reperfusion (1.07 +/- 0.05, p less than 0.05 compared with baseline). Recovery time constants for cyclic variation and wall thickening with reperfusion reflected earlier restoration of cyclic variation (8.1 min) than of wall thickening (420.5 min). Thus, cyclic variation recovers before wall thickening with reperfusion. Its analysis appears to provide a useful index of the presence of viable and potentially salvageable tissue in regions of stunned myocardium that is independent of wall thickening.

Algorithms↗

PubMed1989

Ultrasound integrated backscatter tissue characterization of remote myocardial infarction in human subjects.

To determine whether quantitative ultrasound tissue characterization differentiates normal myocardial regions from segments of remote infarction, 32 consecutive patients with a diagnosis of previous myocardial infarction were evaluated. Images were obtained in real time with a modified two-dimensional ultrasound system capable of providing continuous signals in proportion to the logarithm of integrated backscatter along each A line. In 15 patients, adequate parasternal long-axis images that delineated both normal and infarct segments were obtained with standard time-gain compensation. Image data were analyzed to yield both magnitude and delay (electrocardiographic R wave to nadir normalized for the QT interval) of the cyclic variation of backscatter. Cyclic variation was present in 55 of 56 normal myocardial sites, averaging (mean +/- SEM) 3.2 +/- 0.2 dB in magnitude and exhibiting a mean normalized delay of 0.87 +/- 0.03. The magnitude of cyclic variation in infarct segments was significantly reduced to 1.1 +/- 0.2 dB (42 sites), and the delay was markedly increased to 1.47 +/- 0.12 (21 sites) (p less than 0.0001 for both). In 20 of 42 infarct sites, no cyclic variation was detectable. Thus, ultrasound tissue characterization quantitatively differentiated infarct segments from normal myocardium in patients with remote myocardial infarction.

Adult↗

PubMed1989

Impaired perspective and thought pathology in schizophrenic and psychotic disorders.

Impaired perspective was studied in schizophrenic and thought-disordered patients to analyze hypotheses about its role in thought disorder. Eighty-three schizophrenic patients, other psychotic patients, and nonpsychotic patients judged the adequacy of their own and others' verbalizations under several different conditions. Thought-disordered patients had significantly more impaired perspective than nonthought-disordered patients (p less than 0.05). Patients had significantly poorer perspective about their own verbalizations than about those of other patients (p less than 0.01). Schizophrenic and other psychotic patients showed poor perspective about their own verbalizations. Thought-disordered patients did not view their bizarre verbalizations as stranger than their nonbizarre verbalizations. Impaired perspective and bizarre responses were more frequent under certain conditions. When focusing on the adequacy of their response, patients were significantly less idiosyncratic. The results support the hypothesis that impaired perspective plays a role in thought disorder. A more comprehensive model of thought disorder and disorganization, which includes impaired perspective, is discussed.

Adult↗

PubMed1989

Differentiation between acutely ischemic myocardium and zones of completed infarction in dogs on the basis of frequency-dependent backscatter.

The goal of this work was to determine whether the frequency dependence of apparent backscatter coefficient (not corrected for attenuation within the myocardium) could differentiate completed, remote infarction from acute myocardial injury in vivo. Myocardial infarcts were produced in six dogs by coronary artery occlusion. One to 12 months later, acute ischemic injury was induced in each dog by ligation of a coronary artery that supplied a region of myocardium adjacent to the established infarct. Infarct, ischemic, and normal regions were interrogated with a 5-MHz, circular, 0.5-in. diam, broadband, focused, piezoelectric transducer mounted in a water-filled stand-off device placed against the exposed, beating heart. Apparent backscatter coefficients were measured over the range of frequencies from 3-7 MHz. The frequency dependence was obtained from the slope of log apparent backscatter coefficient versus log frequency. No significant difference in frequency dependence was found between normal and acutely ischemic myocardium for periods of up to 2 h of ischemia. In contrast, frequency dependence in regions of remote infarct (1.8 +/- 0.1, mean +/- standard error) was significantly lower than that in acutely ischemic or nonischemic regions (2.3 +/- 0.1) (p less than 0.01). These results suggest that remote myocardial infarction can be differentiated from acutely injured but still potentially salvageable myocardium in vivo on the basis of the frequency dependence of backscatter.

Animals↗

PubMed1989

Contraction-related variation in frequency dependence of acoustic properties of canine myocardium.

Results of experiments performed in several laboratories indicate that contracting myocardium exhibits a cyclic variation of the magnitude of ultrasonic backscatter, with maxima occurring at end-diastole and minima at end-systole. The mechanisms responsible for this variation are not well understood. The purpose of the present study was to determine whether the frequency dependence of backscatter exhibits systematic variation throughout the cardiac cycle, analysis of which may facilitate improved understanding of biologic factors responsible for the cyclic variation of the magnitude of backscatter. In this study, the myocardial backscatter coefficient, as a function of frequency, was measured throughout the cardiac cycle in nine open-chest dogs. The frequency dependence of the backscatter coefficient was computed from a least-squares linear fit to log backscatter coefficient versus log frequency data. A cyclic variation of frequency dependence of backscatter was found with maximum near end-diastole (f2.6 +/- 0.1) and minimum near end-systole (f2.2 +/- 0.1), a significant variation (p less than 0.01). These results suggest that mechanisms responsible for the cyclic variation of backscatter may include changes in the effective size of the dominant scatterers throughout the cardiac cycle. An alternative explanation for the observed variation is an increase in the myocardial attenuation coefficient during systole followed by a decrease in diastole.

Animals↗

PubMed1989

Ultrasonic tissue characterization with integrated backscatter. Acute myocardial ischemia, reperfusion, and stunned myocardium in patients.

We have previously shown in studies of experimental animals that myocardium exhibits a cardiac cycle-dependent variation of integrated backscatter that reflects regional myocardial contractile performance and that is blunted promptly after arterial occlusion and recovers after reperfusion. To define the clinical utility of ultrasonic tissue characterization with integrated backscatter for detection of acute myocardial infarction and reperfusion, 21 patients (14 men and seven women) were studied in the cardiac care unit within the first 24 hours (mean time, 11.3 hours; range, 3.5-23.8 hours) after the onset of symptoms indicative of acute myocardial infarction with conventional two-dimensional and M-mode echocardiography and with analysis of integrated backscatter. The magnitude of cyclic variation of integrated backscatter was measured from several sites within acute infarct regions and normal regions remote from the infarct zone for each patient. The average magnitude of cyclic variation among all patients (n = 21) was 4.8 +/- 0.5 dB in normal regions compared with 0.8 +/- 0.3 dB in infarct regions (p less than 0.05) within the first 24 hours after the onset of symptoms. Among the patients who had two studies, 15 (mean, 7.1 days; range, 2-31 days for second study) underwent coronary arteriography to define vessel patency. In patients with vessels with documented patency (n = 10), the magnitude of cyclic variation in infarct regions increased over time from 1.3 +/- 0.6 to 2.5 +/- 0.5 dB from the initial to final study (p less than 0.05). Patients with occluded infarct-related arteries (n = 5) exhibited no significant recovery of cyclic variation (0.3 +/- 0.3-0.6 +/- 0.3 dB). A blinded analysis of standard two-dimensional echocardiographic images revealed no significant recovery of wall thickening in either group over the same time intervals. Ultrasonic tissue characterization promptly detects acute myocardial infarction and may delineate potential beneficial effects of coronary artery reperfusion manifest by restoration of cyclic variation of integrated backscatter in the presence of severe wall motion abnormalities.

Aged↗

PubMed1989

Automated determination of the magnitude and time delay ("phase") of the cardiac cycle dependent variation of myocardial ultrasonic integrated backscatter.

An algorithm for quantitative description of cardiac cycle dependent variation of integrated backscatter (cyclic variation) has been developed and is shown to be suitable for analysis of nonsinusoidal data typical of ultrasonic tissue characterization measurements from myocardium in vivo. The algorithm produces estimates of the magnitude of variation and of the time delay relative to the electrocardiographically recorded QRS-complex. To validate the algorithm, 246 integrated backscatter measurements were analyzed both manually and by the automated method. The magnitude and time delay estimates from the two methods correlated closely. With a separate set of data, the algorithm produced reasonable descriptions of the cyclic variation for 89 of 101 integrated backscatter measurements. Only modest computational power is required for effective implementation of this algorithm, facilitating inclusion of online automated analysis capabilities in quantitative ultrasonic tissue characterization systems.

Algorithms↗

PubMed1988

Aplastic anaemia incidence in parts of the United Kingdom in 1985.

This paper describes the distribution of new cases of aplastic anaemia in parts of the UK in 1985. The age, sex and spatial pattern are described. Special attention is given to the investigation of five childhood cases which occurred close in space and time. The results are contrasted with similar data from elsewhere.

Adolescent↗

PubMed1988

Anisotropy of the ultrasonic backscatter of myocardial tissue: I. Theory and measurements in vitro.

This research addresses the variations in the ultrasonic backscatter from specimens consisting of a suspension of approximately aligned cylindrical scatterers in a fluid medium as a function of the angle of propagation in the sample. Predictions of the angular dependence of backscatter based on the time-domain Born approximation described by Rose and Richardson [J. H. Rose and J. M. Richardson, J. Nondestr. Eval. 3, 45-53 (1982)] were compared with experimental measurements of the backscatter from both tissue-mimicking phantoms consisting of graphite fibers suspended in gelatin and from canine myocardial tissue. The angular dependence of the backscatter was predicted and measured to be maximum for propagation perpendicular to the cylinder axes and minimum for propagation parallel to the axes. Maximum to minimum (i.e., perpendicular to parallel) changes in the integrated backscatter were predicted to be between 5 and 10 dB in the phantom. The corresponding quantity measured in both the phantom and in canine myocardial tissue was approximately 6 dB.

Animals↗