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Biomedical subjects

E A Schenk

Publications and source records attributed to E A Schenk.

At least 37 records · Page 2Linked to original sources
PubMed1983

Human anticentromere antibodies: distribution, characterization of antigens, and effect on microtubule organization.

Properties of human anticentromere autoantibodies were analyzed. In intact cells or isolated cell fractions, these sera stain the centromeres of mitotic chromosomes and discrete speckles (prekinetochores) in nuclei. Staining is also retained in matrix preparations from nuclei or chromosomes. Immunoprecipitation or immunoblotting demonstrates protein antigens of 14, 20, 23, and 34 kd in HeLa nuclei and chromosomes; immunoprecipitates of nuclei also contain a protein of 15.5 kd. Matrix preparations contain only the 20, 23, and 34 kd species. Absorption of the anticentromere serum with any one of the four nuclear antigens immobilized on nitrocellulose is sufficient to eliminate centromere staining. Using a lysed cell model for microtubule nucleation, anticentromere sera are shown to inhibit specifically the organization of microtubules at the kinetochore.

Animals↗
PubMed1982

Frequency-dependent angle scattering of ultrasound by liver.

Ultrasonic scattering by one specimen of normal pig liver and two specimens of abnormal human liver has been measured as a function of angle and frequency at each angular position of transmit and receive transducers which were rotated in equal and opposite directions about the axis of a cylindrically shaped tissue sample. Mean data values were determined by averaging points at like frequencies and angular positions in scans made at intervals along the axis of the specimen. Sections of the specimens were obtained throughout its length and stained to emphasize structures containing collagen and connective tissue shown by acoustic microscopy to produce sound speed variations which are known to cause scattering. Using the stained sections as diffraction screens, calculations of scattering were carried out via Fourier transforms on a scale comparable to that in the acoustic studies for comparison with the acoustic data. In all specimens studied, mean acoustic scattering exhibited a general decrease in level with increasing scattering angle. The rate of decrease in acoustic scattering with angle agreed qualitatively with the calculations of average angular falloff of scattering by the stained sections. Lower rates of decrease were observed in tissues with more closely spaced collagen containing structures. Although the data derived from the few substantially different specimens studied is not intended to be representative of all liver, the results show a qualitative correspondence between acoustic scattering and visual appearance which depends on tissue components and their arrangement.

Animals↗
PubMed1981

Etiology of granulomatous disease of the gut (Crohn's disease).

This report is based on a review of the various investigations attempting to determine the etiology of Crohn's disease. It has paid special attention to three main possible etiologic mechanisms, reported in the literature up to the time of this review; namely, immunologic, unknown transmissible agents or known such as L-forms, protoplasts, or spheroplasts, viral or infectious RNA and/or DNA, and a combination of the preceding causative possibilities. It has discussed the unrewarding immunological mechanisms, the failure to confirm the various investigations suggesting a transmissible agent and/or the speculations concerning the possible combination of factors. It also has included the remarks of Sacchar and Auslander, who stated that four important pieces were missing to allow acceptance of transmissible agent as the cause of Crohn's disease. This review has demonstrated that up to the present time the etiology of Crohn's disease has remained a puzzle and concluded that further investigations are necessary to resolve the etiology of Crohn's disease with the suggestion that evidence for an infectious agent will require experiments that satisfy Koch's postulates.

Animals↗
PubMed1979

Ultrasonic detection of myocardial infarction by amplitude analysis.

Myocardial infarctions were produced in dogs by occluding the left anterior descending artery; the dogs were killed at varying times, from 30 minutes to 8 days. Prior to sacrifice, Thioflavin S was injected intravenously. The excised heart was scanned by a B-scanner interfaced with a computer that permitted quantification of signal amplitude. The heart was sectioned, photographed, and studied pathologically. Infarcted myocardium showed high ultrasonic reflectivity with average amplitudes 1.4--2.6 times that of normal muscle. Perfusion-histomorphologic evidence of infarction correlated best in infarcts of 24 hours or less; older infarcts were generally underestimated. Tissue changes, sources of false-positive and false-negative findings, signal processing, and potential clinical utility are discussed.

Animals↗
PubMed1977

Intermittent tachycardia-dependent combined right bundle branch and left anterior conduction block.

A patient is described who had intermittent tachycardia-dependent combined right bundle branch and left anterior conduction block (left axis deviation) with simultaneous onset and disappearance during observations extending over 15 months. Although the site of conduction block could not be definitely determined the pathologic and electrophysiologic data suggest that there was a lesion in the distal part of the His bundle, presumably in fibers already arranged and predestined to supply the right bundle branch and left anterior areas. A single lesion at the so-called pseudobifurcation or two separate lesions with similar electrophysiologic consequences could also account for the observations.

Aged↗
PubMed1977

Cytochemical methods for copper. Semiquantitative screening procedure for identification of abnormal copper levels in liver.

Three previously described histochemical methods for the localization of copper were examined for applicability in the semiquantitative evaluation copper levels in human tissue. Liver tissue obtained at autopsy was stained using dimethylaminobenzylidene rhodanine, rubeanic acid, and diethyldithiocarbamate procedures. The effects of method and time of fixation, staining, incubation time, and variations in procedures were evaluated. Copper levels in tissues examined were determined using atomic absorption spectroscopy. Each staining method was evaluated for sensitivity, reproducibility, and linearity. The rhodanine method was found to produce the most reproducible results, and a linear relationship between microscopical evaluation of the stain and actual tissue copper levels was observed. It was concluded that the rhodanine copper method is applicable for the semi-quantitative evaluation of tissue copper and provides a satisfactory screening method for the identification of abnormal tissue copper levels.

Copper↗
PubMed1976

Iron gallein elastic method---a substitute for Verhoeff's elastic tissue stain.

A method for staining elastic fibers in formalin fixed, paraffin embedded sections is described. After deparaffinizing and dehydration, sections are stained for 30 minutes in a solution prepared by mixing equal parts of 1% gallein dissolved in ethylene glycol and absolute alcohol (1:4), and 1.16% aqueous ferric chloride in 1% hydrochloric acid. The sections are washed in water and then differentiated in 2% ferric chloride for 2 minutes. After washing in water, the sections are counterstained with a variant of Van Gieson's picric acid-acid fuchsin for 1 minute. The results are similar to Verhoeff's elastic stain with elastic fibers staining black. An advantage to this staining procedure is that visually controlled differentiation is not necessary.

Aorta↗
PubMed1976

Energy-dispersive x-ray fluorescence spectroscopy and inductively coupled plasma emission spectrometry evaluated for multielement analysis in complex biological matrices.

Energy-dispersive x-ray spectroscopy and inductively coupled plasma emission spectrometry were evaluated as methods for routine multielement analysis of biological material. Standard samples included Standard Reference Materials (National Bureau of Standards), compounded mixtures, and supplements that provided a wide range of elemental concentrations for analysis. Elements included in this study were Zn, Pb, Ni, Mn, Fe, Mg, Cu, Ca, As, Se, Br, Rb, and Sr. Standards were analyzed as unknowns by participating laboratories. The two methods were evaluated for sensitivity, precision, and accuracy, and the results compared to those obtained for atomic absorption spectrometric analysis of identical standard unknowns. Both methods compared favorably and both were determined to be highly reliable for such an application. Advantages and disadvantages of each method are compared and discussed.

Animals↗
PubMed1976

Pepsin secretion, pepsinogen, and gastrin in "Barrett's esophagus." Clinical and morphological characteristics.

Four cases of Barrett's esophagus are presented. Three cases presented with significant esophageal bleeding and one case presented with high esophageal stricture. Gastrointestinal panendoscopy was done in each case and multiple biopsies were taken. The biopsies were utilized for histomorphology, pepsinogen agar gel electrophoresis, and tissue gastrin assays. Tissue gastrin levels in esophageal mucosa were elevated in 2 cases when compared to controls with and without hiatus hernia. Pepsin and acid secretory studies were done by isolating the esophagus. Barrett's esophagus was shown to produce pepsin by both chemical studies (2 cases) and agar gel electrophoresis at pH 5.7 (3 cases), and was also shown to produce acid. The mucosa contained either cathepsin or cathepsin and pepsinogens in all cases. Nissen's fundoplication was performed in all of the patients. Of 3 patients who were bleeding, 2 who consented for this operation stopped bleeding after the operation. It is to be noted that the usual clinical treatment of antacids, bedrest, and raising the head end of the bed failed in all of the patients. The follow-up of 9 months to 3 years postoperatively has shown persistence of Barrett's mucosa with no evidence for any reversion to normal esophageal type.

Electrophoresis, Agar Gel↗
PubMed1975

Ganglion cells in arterioles of skeletal muscle: role in sympathetic vasodilation.

Ganglion cells were found in arterioles of gracilis muscles of dogs 2 wk after complete extrinsic denervation. We tested the possibility that they function in active sympathetic vasodilation (SVD) induced in isolated gracilis muscles by hypothalamic stimulation. To this end various drugs were injected into the gracilis perfusate. (Drugs did not reach the systemic circulation, and exerted their effects within the gracilis itself). C6 had no effect. Submaximal doses of atropine or l-hyoscyamine delayed and slowed SVD; higher doses blocked completely. d-Hyoscyamine did not change SVD or acetylcholine vasodilation, but when administered prior to l-hyoscyamine, threshold for blockade of SVD by the l-isomer increased 10,000-fold. Blockade by l-hyoscyamine of acetylcholine vasodilation was unaltered by d-hyoscyamine. Eserine partly blocked SVD, but enhanced and prolonged acetylcholine vasodilation. The foregoing and certain features of the time course of SVD are interpreted to mean that: a) atropine blocks SVD at muscarinic sites on peripheral ganglion cells; b) transmission at the ganglion cells depends on slow excitatory postsynaptic potentials; c) the final mediator of SVD at the vascular muscle cell is unknown.

Acetylcholine↗