Search PubMed⌕ Search

Biomedical subjects

J Nichols

Publications and source records attributed to J Nichols.

At least 109 records · Page 6Linked to original sources
PubMed1983

Quantitative texture analysis in two-dimensional echocardiography: application to the diagnosis of experimental myocardial contusion.

We postulated that the analysis of regional image texture in two-dimensional (2D) echocardiograms would be an accurate method to differentiate normal from abnormal myocardial structure. We tested this hypothesis with quantitative texture measures to study the regional, spatial distribution of echo amplitudes in 2D echocardiograms performed before and immediately after blunt left chest trauma was induced in six anesthetized dogs. After trauma the contused region of myocardium appeared brighter and exhibited an altered myocardial texture. By use of a set quantitative texture measures, we found no significant differences in pretrauma images when normal regions were compared with regions to be contused. Also, we found no difference when we compared the normal regions in each animal in pretrauma vs posttrauma images. Twelve measures, however, differentiated normal from contused regions within the posttrauma images (p values ranged from .0057 to .0001 by multivariate analysis of variance). These texture measures were capable of differentiating normal from abnormal tissue only when texture along the azimuthal (lateral) direction was calculated. We conclude that regions of myocardial contusion exhibit visibly altered local echo-amplitude patterns (altered image texture) and that these image texture alterations may be quantified with digital image analysis techniques. These findings suggest that quantitative texture calculations may be a useful approach to ultrasound tissue characterization.

Animals↗
PubMed1983

Detection of acute myocardial infarction in closed-chest dogs by analysis of regional two-dimensional echocardiographic gray-level distributions.

We hypothesized that acute myocardial infarction could be detected in standard two-dimensional echocardiograms of closed-chest dogs by evaluating regional echo amplitude distributions using computerized image analysis. We tested this hypothesis by performing standard, 2.4 MHz two-dimensional echoes before and 2 days after circumflex coronary occlusion in seven closed-chest dogs. Control and infarcted regions of interest were studied in digitized stop-frame images. Average gray level was calculated for each region of interest, and the shape of the gray-level distribution was analyzed by calculation of skewness and kurtosis and by qualitative features of shape. Average gray level increased significantly from the pre- to postocclusion images in the infarcted regions (16.7 +/- 4.2 vs. 32.4 +/- 4.4 units, P less than 0.01), but not in the control regions (17.4 +/- 4 vs. 22.3 +/- 5.5., P = NS). Average gray level could not distinguish between infarcted and normal regions within the postocclusion images (36 +/- 5.2 vs. 33.6 +/- 5.8, P = NS). Three independent observers qualitatively evaluated histogram shape and correctly identified 7/7 MI regions (100% sensitivity) and 14/20 normal regions (70% specificity). Quantitatively, infarct regions exhibited a significant decrease in kurtosis from pre- to postocclusion images (7.1 +/- 4.0 vs. 5.2 +/- 2.9, P = NS). Within postocclusion images, infarcted regions displayed a significantly lower kurtosis than did normal regions (0.27 +/- .47 vs. 2.5 +/- 1.0, P less than .01). We conclude that acute myocardial infarction may be detected in closed-chest dogs by analyzing regional echo amplitude data from standard two-dimensional echocardiograms.

Animals↗
PubMed1981

Establishing a low back school.

We present a plan for establishing a facility for conservative treatment of patients with low back pain. This system is based on a concept of one therapist instructing one patient in certain anatomy and body mechanics appropriate to his needs. Audiovisual programs are used in this part of the program. Exercises are prescribed for specific muscle groups important in achieving proper postures during the activities of daily living and to stretch contractures that contribute to lordotic stresses on the lumbar spine. After the completion of three or four sessions necessary to achieve reeducation, the patient is asked to demonstrate his proficiency on an obstacle course. The various requirements in terms of personnel, space, equipment, and printed material for establishing such a low back school are enumerated.

Activities of Daily Living↗
PubMed1978

Effect of sanguinarine, a benzophenanthridine alkaloid, on frog skin potential difference and short circuit current.

Sanguinarine, a benzophenanthridine alkaloid, causes a initial stimulation of frog skin short circuit current Isc when present in the mucosal bathing medium at 10(-4) M. The stimulation is accompanied by an increase in spontaneous potential difference (PD) and increase in D.C. resistance. No effects are seen with sanguinarine in the serosal bathing medium. The initial stimulation is followed by a decrease in Isc and PD, but a continued increase in resistance. In skins whose initial spontaneous PD is high, no initial stimulation in Isc and PD is seen; however, clamping these skins to a lower potential does not alter their initial inhibitory response to sanguinarine. Likewise, clamping the lower potential skins to higher potential does not alter their initial stimulatory response. Sanguinarine seems to be acting on the permeability barriers at the outer surface of the frog skin.

Alkaloids↗
PubMed1974

Adrenal cortical degeneration and regeneration following administration of DDD.

Degeneration and regeneration of canine adrenal cortical cells following DDD administration are described. The degenerative phase is rapid in onset and dose related. It is morphologically characterized by profound cytoplasmic vacuolation due to severe mitochondrial damage, disruption of the smooth endoplasmic reticulum, autolysosomal response and lipid accumulation. Toxic necrosis with a mononuclear cell reaction and fibrosis also occurs. The regenerative phase consists of centripetal cellular regeneration, cellular repair and some residual damage. Several of the ultrastructural and biochemical findings are discussed in relation to the pertinent literature.

Adrenal Gland Diseases↗