PubMed Health⌕ Search

Biomedical subjects

J W Mimbs

Publications and source records attributed to J W Mimbs.

16 recordsLinked to original sources
PubMed2001

Tardive dyskinesia--diagnostic issues, subsyndromes, and concurrent movement disorders: a study of state hospital inpatients referred to a movement disorder consultation service.

Of 49 state hospital patients referred for movement disorder consultation for tardive dyskinesia (TD), 11 (23.9%) of 46 meeting inclusion criteria had movement disorders other than TD. These other disorders led to a false diagnosis of TD in 6 subjects (12.2%). Between-day dyskinesia variability affected TD ascertainment in only 3.2 percent of subjects. Prevalences of other neurological conditions in the 30 patients identified with definite TD were parkinsonism (90%), dystonia (25%), akathisia (16%), cerebellar signs (40%), dysmetria (23%), cerebellar tremor (17%), tardive dystonia (3.3%), and tardive akathisia (3.3%). Concurrence rates of parkinsonism with TD varied significantly according to which clinical signs were used to define parkinsonism. Using a rating score threshold of at least mild, rigidity occurred in 79.3 percent, bradykinesia in 55.2 percent, and resting tremor in 41.4 percent of subjects with TD; more significant rigidity occurred in 41.4 percent, bradykinesia in 31.0 percent, and resting tremor in 20.7 percent. Concurrence rates of neurological conditions with TD subsyndromes were distributed rather evenly according to condition prevalences, except for an association of cervicotruncal TD with bradykinesia (perhaps because of ventromedial striatal presynaptic and postsynaptic D2 blockade, respectively). These findings, as well as the occurrence of equal gender ratio and relative under-representation of bipolar and alcohol disorders in subjects with definite TD, are discussed.

Aged↗
PubMed1981

Detection of cardiomyopathic changes induced by doxorubicin based on quantitative analysis of ultrasonic backscatter.

Ultrasonic measurements are valuable in characterizing cardiac dimensions and structure. Recently, analysis of ultrasonic properties of tissue has proved useful in detecting morphologic changes such as those accompanying myocardial infarction. This study was undertaken to determine whether acoustic properties of tissue can be utilized to detect cardiomyopathic changes as well. Cardiomyopathy was induced by prolonged administration of doxorubicin (Adriamycin) (1.2 mg/kg twice weekly) in 25 rabbits and results were compared with those in normal control rabbits, housed identically. The 15 surviving treated animals were killed at selected intervals to 10 to 18 weeks after initiation of drug administration and the hearts were analyzed for collagen content based on hydroxyproline. Regional ultrasonic backscatter was assessed with a frequency-averaging procedure to minimize effects of phase cancellation and with an independent method employing spectral display over the frequency range of 1 to 11 megahertz from which an index of backscatter at a single frequency (2.25 megahertz) could be calculated. In hearts from treated animals, collagen content was significantly increased (p less than 0.05). Integrated ultrasonic backscatter was markedly increased (by more than 500 percent, that is, equivalent to 7 decibels) in fibrotic regions and significantly, although less markedly, in myopathic regions without marked collagen deposition. Thus, increased backscatter correlated with collagen deposition. Backscatter at 2.25 megahertz was significantly increased (by more than 500 percent, that is, equivalent to 7 decibels) in fibrotic regions. These results indicate that alterations in acoustic properties occur in cardiomyopathic tissue and that such alterations can be detected with the use of reflected ultrasound. Accordingly, assessment of integrated backscatter offers a promising approach for early clinical detection and characterization of evolution of cardiomyopathy induced by doxorubicin or of other causes.

Animals↗
PubMed1981

Relationship between collagen and ultrasonic backscatter in myocardial tissue.

The relationship between ultrasonic backscatter and collagen concentration estimated on the basis of hydroxyproline concentration was examined in hearts from normal dogs and in hearts from dogs subjected to ischemic injury by coronary occlusion as an approach toward elucidating the physical mechanisms underlying the scattering of ultrasound by soft tissue. Ultrasonic backscatter was found to increase significantly in regions of ischemic injury studied 5--17 weeks following occlusion. The average backscatter coefficient was six time larger in regions of infarct studied 8--10 weeks after occlusion than that in regions of infarct studied 5--6 weeks after occlusion. In contrast, the average hydroxyproline concentration, a quantitative index of molecular collagen content, for regions of infarct was only about 25% larger at 8--10 weeks compared with that at 5--6 weeks after occlusion. These results may suggest that the magnitude of ultrasonic scattering in regions of remote myocardial infarct is sensitive not only to the concentration of molecular collagen but also to the organizational state of this structural protein. In addition, the results of this study may indicate that scattering represents a small fraction of the total attenuation coefficient in a biological system exhibiting either low collagen concentration (normal myocardium) or significant collagen concentration (scarred myocardium).

Animals↗
PubMed1981

Effects of myocardial ischemia on quantitative ultrasonic backscatter and identification of responsible determinants.

Quantitative characterization of myocardial properties represent a rapidly emerging area of echocardiographic investigation. Because measurement of the ultrasonic integrated backscatter is theoretically applicable to analysis in vivo with reflected ultrasound, this study was performed to develop and evaluate a suitable method for measurement of quantitative backscatter in vivo. In view of the desirability of characterizing ischemic myocardium noninvasively, the study was performed with animal preparations simulating myocardial ischemia in humans. In one series of open-chest dogs, integrated backscatter among 22 ischemic regions was increased by 200% (P less than 0.01) compared to values in control regions within 1 hour after coronary occlusion and by 400% (-45.1 +/- 0.7 dB compared to -50.9 +/- 0.4 dB) (P less than 0.001) within 6 hours. In a second series of open-chest dogs, ischemia was quantified with 141Ce microspheres, and mean integrated backscatter was found to increase (280% of control) (P less than 0.01) in regions with flow less than 20% of control 2 hours following coronary occlusion. Additional studies with perfused hearts revealed two determinants of the increased ultrasonic backscatter observed: (1) an increase in cardiac fluid content reflected by the wet-to-dry weight ratio, and (2) the contributions of formed elements in whole blood. The results indicate that ultrasonic integrated backscatter distinguishes severely ischemic from nonischemic myocardium in vivo in open-chest animals. Because it was possible to obtain these results in the reflection mode, potential extension of the approach to clinical applications is promising.

Animals↗
PubMed1979

The relationship between collagen and ultrasonic attenuation in myocardial tissue.

The relationship between ultrasonic attenuation and collagen content is examined in hearts from normal dogs and in hearts from dogs subjected to ischemic injury by coronary occlusion as an approach toward elucidating the physical mechanisms responsible for the attenuation of soft tissue. Increased ultrasonic attenuation is shown to correlate well with increased collagen concentration determined biochemically in regions of ischemic injury studied 2, 4, and 6 weeks following occlusion. Extrapolation of experimentally determined relationship between attenuation and collagen concentration suggests that collagen is responsible for not more than 15% of the attenuation observed in normal myocardium. These results indicate that collagen appears to be the principal determinant of the elevated attenuation detected in regions of myocardial infarction, but is apparently not the primary determinant of the attenuation of normal myocardium.

Animals↗
PubMed1979

Changes in ultrasonic attenuation indicative of early myocardial ischemic injury.

This study was designed to determine whether quantitative alterations in ultrasonic attenuation are associated with myocardial changes occurring after acute ischemic injury. Five hundred seventeen regions of myocardium from 41 dogs were studied in vitro at five intervals after coronary occlusion: 15 min, 1 h, 6 h, 24 h, 3 days, and 6 wk. Quantitative indices of ultrasonic attenuation were determined from the measured frequency dependence of the ultrasonic attenuation coefficient characterizing each myocardial region over the range 2-10 MHz. Independent definition of regions of ischemic injury was provided by either creatine kinase depletion or colloidal carbon dye distribution. Results of this study indicate that ischemic myocardial regions investigated 15 min to 24 h after coronary occlusion demonstrated ultrasonic attenuation significantly decreased from nonischemic regions (P less than 0.05). In contrast, ultrasonic attenuation was significantly increased in zones of ischemia or infarction investigated at 3 days and 6 wk after coronary occlusion (P less than 0.05 and P less than 0.01, respectively). These results indicate that altered attenuation of transmitted ultrasound by myocardium in vitro is an early manifestation of ischemia.

Animals↗
PubMed1977

The effect of respiration on normal and abnormal Q waves. An electrocardiographic and vectorcardiographic analysis.

The diagnostic significance of Q waves in Leads II, III, and aVF when analyzed retrospectively remains controversial. Persistence of the Q wave on inspiration is said to reflect inferior infarction. Studies in the past, which have evaluated respiratory variation as a means to separate normal from abnormal Q waves, were performed utilizing the ECG only, were often retrospective, and frequently there was inadequate documentation of myocardial infarction. The present study was performed prospectively and utilized both electrocardiographic and vectorcardiographic analysis of the first 30 msec. vector before and after inspiration in 33 patients with documented acute myocardial infarction and in 22 normal volunteers. Inferior myocardial infarction was documented prospectively by ECG, VCG, by conventional enzymes, and by MB CPK. The VCG demonstrated increased sensitivity over that of the ECG, but the effect of inspiration noted on ECG and VCG was variable and extremely unreliable as a means of separating normal from abnormal Q waves.

Electrocardiography↗
PubMed1977

Ultrasonic attenuation of myocardial tissue: dependence on time after excision and on temperature.

The ultrasonic attenuation coefficient of myocardium over the frequency range 2-10 MHz has been measured in vitro as a function excision and as a function of temperature. Results indicate that the attenuation coefficient was approximately independent of time for 4 h following excision at 19.5 degrees C, but increased by about 20% over a 4-h interval at 35 degrees C. The attenuation coefficient decreases approximately linearly with increasing temperature over the range 20.5 degrees -37 degrees C, with the value at 37 degrees C being about 20% lower than at 20.5 degrees C.

Animals↗
PubMed1977

Detection of myocardial infarction in vitro based on altered attenuation of ultrasound.

This study was designed to determine whether attenuation of ultrasound by myocardium is potentially useful in detecting and quantifying infarction. Accordingly, we analyzed 44 regions of myocardium from 11 dogs 4-10 weeks after coronary occlusion. Attenuation of ultrasound in each region was assessed by transmitting a broadband pulse through the tissue in vitro and carefully gating the appropriate pulse into a spectrum analyzer for Fourier analysis (frequency range, 2-9.5 MHZ). An ultrasonic index of attenuation was derived from the slope of the best-fit line relating attenuation and frequency obtained from the Fourier transform. Acquistion of ultrasonic data was improved with the use of a specially designed small diameter receiving transducer. Myocardial creatine kinase content was assayed in each region to provide an independent index of regional injury. Results obtained from ultrasonic and biochemical analyses correlated with a correlation coefficient between the two of 0.80 in 24 regions of myocardium from the six dogs studied 4-5 weeks after infarction, and 0.72 in 20 regions from the five dogs studied 9-11 weeks after infarction. These findings indicate that regional infarction is associated with quantitative changes in ultrasonic attenuation.

Animals↗
PubMed1977

Perioperative mortality rate in patients with unstable angina selected by exclusion of myocardial infarction.

Coronary bypass surgery may be associated with an increased perioperative mortality rate in patients with unstable compared to stable angina. The mortality rate is excessively high when surgery is performed during evolving myocardial infarction. Elevated plasma MB CPK isoenzyme activity is a remarkably sensitive and specific marker of myocardial damage. Accordingly, we studied 111 patients with unstable angina to determine whether exclusion of patients with initially elevated MB CPK improves the perioperative mortality rate. Plasma MB CPK activity was assayed prior to catheterization and every 2 hours therafter. Of the 111 patients, 16, with initially elevated MB CPK activity, were excluded and managed medically. Catheterization was performed in 59 patients, and severe vessel obstruction was documented in 55. Coronary bypass surgery performed in 47 patients was associated with a mortality rate of 4 per cent. Thus, after exclusion of patients with evolving infarction by MB CPK isoenzyme analysis, catheterization and coronary bypass surgery in patients with unstable angina resulted in a mortality rate comparable to that in patients with stable angina.

Adult↗
PubMed1976

Spontaneous cardiac tamponade due to sternotomy wire suture.

The first case of spontaneous cardiac tamponade caused by wire suture for sternotomy closure is presented. The proper analysis of bloody pericardial fluid, including simultaneous aspirate and venous hematocrit, oxygen content, and coagulation studies, is emphasized. In addition, the causes of acute hemopericardium are reviewed. Spontaneous cardiac tamponade as a potential late complication of cardiac surgery should be considered in the postoperative patient who presents with pericarditis or a sudden change in cardiac status.

Adolescent↗
PubMed1975

Echocardiographic detection of mitral valve prolapse. Exclusion of false positive diagnosis and determination of inheritance.

An important potential source of error in the echocardiographic diagnosis of mitral valve prolapse has been identified -- namely a systolic hammock-like pattern of the anterior and/or posterior mitral leaflet echoes, similar to that associated with true mitral valve prolapse, produced artifactually when the ultrasonic transducer is angulated inferiorly. Utilizing a modified, more specific technique we characterized the mode of inheritance and familial prevalence of this disorder. Among 74 subjects, composed of 57 first-degree relatives and 17 propositi with mitral valve prolapse, mitral valve prolapse was detected in 27 of 57 (47%) of the first-degree relatives. Fifty-three percent of female and 36% of male progeny of propositi were affected. Furthermore, familial transmission occurred from propositi to both sexes. Results of this study indicate that mitral valve prolapse is transmitted in an autosomal dominant mode with reduced male expressivity and a familial prevalence of 47% and that appropriate echocardiographic techniques must be employed to avoid a high incidence of false positive diagnosis.

Adolescent↗