Biomedical subjects
Publications and source records attributed to T Hildebrand.
The authors describe a double contrast X-ray picture of varicosities of the large intestine. In the literature so far irrigoscopic changes specific for varicosities were not described. The authors observed that the defect of the filling increased after Valsalva's manoeuvre. The authors consider this symptom specific for varicosities.
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Accommodation was measured in a variety of waterfowl by projecting parallel low power helium-neon laser beams through the pupils of excised eyes placed in saline. The posterior globe was removed, allowing the beams, refracted only by the lens, to focus well behind the eye. Electrical stimulation of the ciliary muscle results in accommodative movement of the focal point toward the eye. Study of video recordings show that diving ducks (Mergus cucullatus and Bucephala clangala) can accommodate the 70-80 D needed to focus light on the retina when the eye is in water. Diving and nondiving species are compared in amount and rate of accommodation.
Concern has been expressed in the literature regarding the frequency and amount of astigmatism found in patients with intraocular lens implants. Postoperative tilting of the implants is one suggested cause. We have measured the effect of tilt on focal length in lenses supplied by two companies. The method used involved photographing the refractive effect of lenses on fine parallel laser beams as the lenses were tilted to varying degrees. The results show that: (a) drastic tilting (e.g. 20 degrees) is required to produce significant amounts of variation in focal length, (b) the effect on back vertex power is more important, (c) spherical aberration of the lenses is minimized.
The authors describe the submicroscopical structure of surface epithelial cells of the mucosa and cells of the stomach gland cervix in men. On the basis of electronmicroscopic studies of bioptic samples of the stomach mucosa the surface epithelium of the stomach mucosa in men was found to be covered with high cylindrical cells showing typical small, relatively low microvilli at the luminal side with numerous mucous granules in the supranuclear zone of the cells. The basal part of the cell is extremely dense containing numerous ribosomes, a Golgi apparatus and mitochondriae. Isthmic cells were found to differ from surface cells by the location of the nucleus and the amount of mucous granules, which are larger and granular in the rule. The cells of this zone are mutually connected by desmosomes. The granular endoplasmic reticulum is present at a relatively lesser amount as compared to the former group of cells. These cervical cells are of importance from the viewpoint of regeneration and may differentiate into the other cell types of the stomach mucosa.
Compared was the detection of Giardia intestinalis in duodenal contents and in the stool. During endoscopic examination duodenal contents were recovered by means of a tube attached to the mucosa and by aspiration from the region of pars verticalis. In 102 persons, duodenal and stool examinations revealed four and five cases of Giardia infection, respectively. The results showed that both diagnostic methods are equivalent and demonstrated that parasitologic examinations of patients suffering from dyspeptic disorders are very useful.
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Inhomogeneous and anisotropic processing stages developed in the visual system during evolution in order to match a (certainly highly complex) biological optimality criterion. As the examples presented in this paper show, scenes viewed can be separated according to their information content with filter stages such as processing of the central area of the picture field in a wide band fashion, where each detail is perceived and the contrasts are amplified. This requires good illumination as the amplification is small. At the periphery the amplification is higher which favors twilight vision. Especially the sensitivity for moving patterns is highly developed and a band pass prefilter requires only spatially narrow band channels in the course of further processing. Direction specific filter stages make it possible to solve special problems such as the reconstruction of a form from an illuminance distribution.
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The author stated an increased serum level of A-vitamin and triglycerides in non-dialysed and dialysed patients with chronic renal insufficiency. The beta-carotene-serum level was higher only in the group of the non-dialysed patients. Under influence of the haemodialysis a reduction of the triglycerides in the serum developed. A linear correlation between the beta-carotene and the cholesterol serum level in non-dialysed patients and the vitamin A and the triglyceride serum level in patients in the permanent dialysis programme. Finally follows a discussion of the authors on the metabolic sequels of the A-hypervitaminosis in the uraemic syndrome of patients with chronic renal insufficiency.
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