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Biomedical subjects

E Schultz

Publications and source records attributed to E Schultz.

At least 145 records · Page 8Linked to original sources
PubMed1980

Fan-beam computerized tomography systems with rotating and with stationary detector arrays ('third' and 'fourth' generation).

Part I of the present work describes the fundamental problems important for understanding the function of fan-beam computerized tomography systems. First, the relationship between the number of detectors, the number of attenuation profiles, the number of volume elements in which the object slice is decomposed and the number of picture elements in the final image is explained. Then the influence of both the detector width and the sampling distance on the accuracy at which the attenuation profiles can be measured, is defined. Three spatial frequencies play an important part: the aperture cutoff frequency, the sampling frequency, and, coupled with the latter, the Nyquist frequency. Finally, the modulation transfer function, one of the most important quantitative characteristics of any computerized tomography system, is described. Part II of the present work describes the essential design characteristics of fan-beam computerized tomography systems with rotating as well as with stationary detector arrays. It is shown that both types of CT systems have been produced with different implementations. It is further explained that both CT types apply different sampling processes and, moreover, differ in image reconstruction techniques. However, it should be noted that this work presents only fundamental facts and does not attempt to be detailed.

Models, Theoretical↗
PubMed1979

Developmental fate of skeletal muscle satellite cells.

Radioisotopically labeled satellite cells from clonal cultures were implanted into normal muscle of the original donor. Implanted cells invariably retained their myogenic potential by participating in the regeneration of damaged myofibers or in the development of existing fibers.

Animals↗
PubMed1979

Excision of DNA damage arising from chemicals of different carcinogenic potencies.

Primary cultures of mouse embryo cells are more efficient in excising DNA-carcinogen adducts resulting from exposure to either 7-bromomethylbenz-[alpha]anthracene or the more carcinogen 7-bromomethyl-12-methylbenz[alpha]anthracene than are mouse L 929 cell suspension cultures. However, within each of these systems, the excisabilities of the adducts formed by either bromo-compound are similar, so differences in carcinogenic potency of the compounds cannot be attributed to differences in the excisability of their DNA-adducts.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1979

[Image characteristics of the computer tomograph (author's transl)].

In the present paper the images produced by spheres of varying diameter (d = 4,6,8,10 mm) embedded in a homogeneous substance of varying densities (H' = 3,48,93,137 Hounsfield units) as produced by computer tomography were studied. Measurements show that for each sphere diameter there is a minimum contrast between the substance of the sphere and its surroundings which must exist in order to show this sphere by computer tomography. It was also shown that the partial volume effect is of significance for the attenuation of the spheres. The effect of the position of the spheres within the slices to be imaged was studied. The results clearly indicate that in the investigation of small tissue changes in the body, the thickness of the slice and patient displacement should be kept as small as possible.

Absorptiometry, Photon↗
PubMed1979

[Image properties of computer tomography. III. Measurements on homogenous materials. Relationship of attenuation and scatter to various parameters (author's transl)].

The present paper investigates the variations due to various parameters on the image of homogeneous materials as obtained with the Somatom CT scanner. Sugar solutions were used with concentrations equivalent to the absorption values of soft tissues. Because of quantum noise, attentuation at various points is not uniform, but is distributed in a Gaussian manner round a mean value. Using the Evaluskop it was possible to determine the degree of scatter. It was shown that, with increasing density of the material, the scatter increased and that this can be reduced by subjecting the tomogram to a smoothing process. It was further shown how the scatter depends on various parameters, such as thickness and dose. The amount of scatter in a tomogram is important in determining the density gradation which can be a achieved.

Absorptiometry, Photon↗
PubMed1978

Changes in the satellite cells of growing muscle following denervation.

Satellite cells exhibit a number of distinct morphological changes after denervation which appear to be a direct response to nerve section or altered functional state of the muscle fibers. These changes appear generally related to increased movement and overall activation of the cells. After longer periods of denervation many satellite cells appear to separate from their fibers and become free cells in the interstitial space. It is proposed that this mechanism provides a cellular source for the small-diameter, immature fibers dispersed throughout the muscle after two to three weeks. Although neo-formation of myofibers appears to be a feature of denervated growing muscle, an increase in total fiber population was not observed. It is suggested that in the absence of a viable nerve supply the new fibers degenerate.

Animals↗
PubMed1978

The effect of Marcaine on muscle and non-muscle cells in vitro.

The effect of the local anaesthetic Marcaine on muscle and non-muscle cell types was examined using an in vitro assay. Each of the cell types examined (myotubes, myoblasts, fibroblasts and liver parenchyma) expressed morphological alterations when incubated in Marcaine-medium. Myotubes were the most sensitive of the cells studied and exhibited several pronounced membrane structural changes after short incubation periods in Marcaine-medium. The toxic effects of Marcaine were irreversible and the myotubes continued to degenerate despite being placed in fresh medium. Myoblasts and non-muscle cells, however, demonstrated a rapid recovery when removed from the Marcaine-medium. Since Marcaine is thought to complete with Ca++ for specific sites on cell membranes, it is proposed that the differential effects which were observed are dependent upon the level of calcium related activities being carried out by the cells.

Animals↗
PubMed1978

[Phantom measurements of spatial resolution and the partial-volume-effect in computer tomography (author's transl)].

The present work deals with the problem of demonstrating tissue changes of small volume by computer tomography. Measurements were carried out with the Somatom computer tomograph and evaluated by the Evaluscope (both Siemens); fourteen test situations were devised, using plexiglass rods of varying diameter and different penetration into the level being sectioned. Quantitative relationships were found concerning the spatial resolution for objects of varying sizes, concerning the partial volume effect and the thickness of the section for objects of varying size, and concerning the relationship between resolution and partial volume effect for small objects.

Models, Structural↗
PubMed1977

[Serumferritin in patients with malignant lymphomas (author's transl)].

Serum of 70 patients with malignant lymphoma was tested for concentration of ferritin by immunoradiometric assay. Serum of patients with Hodgkin's disease showed an apparently increased ferritin concentration only in the stage III and IV. Concentration of serum ferritin was found normal in patients with chronic lymphocytic leukemia and non-Hodgkin's lymphoma of low malignancy. Among patients with non-Hodgkin's lymphome of high malignancy only one who suffered from advanced immunoblastic sarcoma showed increased concentration of serum ferritin. Patients with elevated concentration of serum ferritin had a decreased level of serum iron and showed also anemia. Their bone marrow reticulum was rich in dyeing iron. These results suggest that hyperferritinemia in patients with advanced Hodgkin's disease is related to a lack of release of iron from reticuloendothelial system.

Bone Marrow↗
PubMed1976

Fine structure of satellite cells in growing skeletal muscle.

The morphology of satellite cells was investigated in skeletal muscle from mice of various ages between 7 days and 50 weeks. Satellite cells of very young muscle had abundant cytoplasm which was rich in organelles. Free ribosomes were abundant and usually arranged into polysomes of 5-6 units. Cisternae of rough endoplasmic reticulum were heavily studded with ribosomes and occupied the polar regions of the cytoplasm. Marked dilations of the cisternae, filled with an amorphous electron-lucent material, were a frequent and characteristic feature of satellite cells of very young muscle. The cytoplasm of young cells also contained a well developed Golgi apparatus as well as numerous mitochondria, microfilaments and microtubules. With increasing age there was a rapid reduction in organelles both qualitatively and quantitatively. For rxample, as the number of ribosomes decreased, their organization into polysomes was lost. The rough endoplasmic reticulum was present in cells of older muscle merely as small isolated profiles that lacked dilations. These and other features demonstrated during this study are consistent with the concept that satellite cells are metabolically very active in young muscle but rapidly become quiescent as the animal grows older.

Age Factors↗
PubMed1976

The fate of the untreated alcoholic. Toward a natural history of the disorder.

Eighty-three male alcoholics were administered a structured interview when they appeared at a large general hospital for treatment of a variety of disorders. These represent 83 consecutive cases. None received treatment aside from brief "drying-out" but all were accepted as participants in a research program. Seventy-three (88 per cent of the sample) were located for a 3-year follow-up; five of these were not seen at the 1-year follow-up, and 10 were known to be dead. This paper focuses on 58 of the alcoholics who were seen at all three evaluations, and the 10 who were known dead. The data are presented as indicating the long term results of, at best, a mild or minimal intervention with male alcoholics. A small, but significant improvement was noted on several life-adjustment scales between the initial and 1-year evaluation (OYE), but no further improvement was seen between OYE and the 3-year evaluation (TYE); 19 percent were abstinent for 1 year and 10 per cent for the full 3-year period. The best predictor of TYE abstinence was OYE abstinence, but only for the extremes, i.e., no abstinence or total abstinence. Abstinence success was also related to a tendency to use community resources, lower number of mental hospitalizations, higher occupational status, higher global rating and, curiously, lower interpersonal adjustment rating. The group using Alcoholics Anonymous showed no better outcome than the group using no community resources at all. The mortality rate was 12 per cent over the 3 years or slightly more than 4 per cent a year. The suicide rate was about 4 per cent over the 3 years. The ratings for those dying showed a pattern of more admitted drunken arrests and heavy recent drinking superimposed on lighter overall drinking for the past year. The study demonstrates that even untreated alcoholics can be traced and effective follow-up studies completed. Results also indicate that over long time periods and left to their own devices, many alcoholics do seek out some form of help. But such assistance tends not to be sustained or intensive and a good portion of it is nonprofessional and nonmedical. Moreover, a surprisingly substantial number (31 per cent) of hospital-identified alcoholics apparently neither seek out nor receive any help at all after their initial identification; yet their self-reported life-adjustment ratings do not differ significantly from those who do seek help. The no-help receivers may be the most critical group of all to follow, as they are trule untreated. It would be important to determine how consistent in fact they are in their avoidance of help, what accounts for that behavior, and whether their ultimate fate is different from those who regularly seek assistance.

Alcohol Drinking↗