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Biomedical subjects

K Knyrim

Publications and source records attributed to K Knyrim.

At least 37 records · Page 2Linked to original sources
PubMed1989

Optical performance of electronic imaging systems for the colon.

Electronic (video) endoscopes are a significant new development in gastroenterology, offering the potential of enhanced teaching and permanent storage of pictorial data. The primary concern of gastroenterologists is the resolution and color performance of these instruments, as these parameters have important bearings on the ability to discern pathological changes in mucosa. We sought to determine the resolution and color capabilities of electronic colonoscopes and compare them with a conventional fiber colonoscope. Resolution was determined using a standard test chart at various distances and the number of picture elements (a measure of resolution) was calculated. The mean number of picture elements was Fujinon (219), Fiber (172), Pentax (169), Toshiba (142), Olympus (140), and Welch Allyn (133). In close focus examination (target distances less than 1 cm), the Fujinon and Toshiba endoscopes had significantly higher resolution than the other instruments. Color was measured quantitatively using a standard color chart and a color analyzer. Color polygons were plotted for each endoscope on a reference chromaticity diagram. All systems had an acceptable overall performance but color was undersaturated with some systems. The optical performance of electronic endoscopes has improved considerably since the inception of electronic endoscopy.

Colonoscopes↗
PubMed1987

Electronic endoscopy--the latest technology.

At present, video endoscopic systems (VE) are available from four companies. We have had an opportunity to test these instruments in clinical practice. In principle, all the VE's are similar in that they employ charge coupling devices (CCD-chips) as image sensors, but they differ significantly in CCD chip technology and in the color acquisition technique. The basic aspects of CCD chip and transmission technology of relevance to the endoscopist are discussed. The mechanical properties of the endoscopes are listed. Finally, we provide an outlook on the determinants of the optical performance of VE's. The optical performance of a VE can be characterized by its resolution and color performance.

Colonoscopes↗
PubMed1987

Video-endoscopes in comparison with fiberscopes: quantitative measurement of optical resolution.

The subject of this study was the optical performance of video-endoscopic systems (VE) in terms of maximal resolving power and resolvable picture elements. Olympus, Toshiba/Machida, Fujinon, and Welch Allyn video gastroscopes were tested. A GIF Q 10 fiberscope from Olympus was also included for comparison. The resolution measurements were made at various distances using two independent methods--electronic analysis of the TV signal, and visual evaluation of the resolution, of a standardized test target. The results obtained with the two methods were in perfect agreement. The resolution of fine details clearly depends on the distance between the distal end and the target because of decreasing image scale. Depending on the individual optical design, the various VE's show maxima at different distances. At shorter distances, the image is degraded by defocusing. An optimal distance which is as small as possible is desired for clinical routine. Apart from the fiberscope this requirement is best met by the Fuji system. The greatest resolution is obtained with the Toshiba system but at the cost of the viewing angle which is the smallest of all the systems. Fuji combines relatively high resolution with a large viewing angle. Because of the widely varying viewing angle a comparison based solely on resolution cannot represent the true imaging capability of the system. We therefore eliminated purely optical parameters and calculated the number of resolvable picture elements per line. We regard this number to be a fair characterization of both TV and fiber systems.

Fiber Optic Technology↗
PubMed1987

Color performance of video endoscopes: quantitative measurement of color reproduction.

We have conducted a study aimed at testing the color performance of video endoscopes in quantitative terms for the first time. The video endoscopes investigated were from Fuji, Olympus, Toshiba/Machida, and Welch-Allyn. The tests were carried out with an opto-electronic color analyser using standardized color charts and a neutral grey chart. Hue and chroma of the reproduced colors were measured. The Olympus video endoscope reproduces the hue very well, showing only slight color desaturation. The Fuji video endoscope had a yellowish tint, whereas the picture obtained with the WA video endoscope produced an inhomogeneous picture with a pronounced red/purplish cast at the top of the screen and almost neutral reproduction at the lower half. The Toshiba video endoscope was the only one with a color chip, and reproduced hue fairly well, but its colors were weakly saturated.

Color↗
PubMed1987

Computer-aided formulation of physician's reports and storage of ERCP data.

In the 2nd Medical Dept. of the Technical University of Munich, endoscopic retrograde cholangiopancreatography (ERCP) reports are written with the aid of a computer. The doctor doing the examination enters the ERCP data into screen masks. The data are stored at once in a data bank. This data bank system permits immediate error checks of the variables entered, singly and in combination. Errors can be corrected in a loop. Generating of ERCP reports is controlled by a text file, which contains both control statements and standard phrases. A special program for the document generating was developed by the authors and has been used for 15 years in various applications.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1986

Electronic endoscopy--fibres or chips?

The video endoscope represents a new generation of endoscopic instruments. The main feature is an intragastric CCD-chip transforming the optical impulses into electronic signals. The latter are transmitted without any optical fibre bundle, transformed by a video processor and visualized on a television screen. The present experience show drawbacks in respect to mechanical properties of the endoscopes, to reproduction of colors (esp. red) and photographic documentation. On the other hand the excellent image quality guarantees convenient handling for investigator, information for attending persons (doctors, nurses, students), improved conditions for documentation and control of quality. Although the video-endoscope is not replacing fibre endoscopes at present, further improvement will promote its general acceptance.

Endoscopes↗
PubMed1985

[Rectoscopy: rigid or flexible? A comparative study].

The customary rigid rectoscope was compared prospectively, with a new, flexible one (prototypes of Olympus Opt. and Fuji) in each of 114 patients selected at random. Maximal depth of introduction was reached on average after 1 min with the rigid instruments, after 1 min 40 sec with the flexible one. Mean depth of introduction was 16 cm for the rigid and 33 cm for the flexible one. In 21 patients (18.4%) additional information was obtained with the flexible rectoscope. 80% of patients reported that the flexible instrument caused them no or only slight discomfort. Skill in using the flexible instrument can be quickly acquired.

Fiber Optic Technology↗
PubMed1985

[Endoscopic balloon dilatation in stenosis of the pancreatic duct orifice (case report)].

We report the history and endoscopic treatment of a 63 year old female patient with chronic pancreatitis and stenosis of the pancreatic duct. Several operations of the biliary system had been performed in this patient previously (cholecystectomy 1964, choledochoduodenostomy 1972, revision of the choledochoduodenostomy 1974). In 1976 a chronic pancreatitis and a prepapillary stenosis of the Ductus wirsungianus has been diagnosed by clinical and endoscopic radiological findings. In order to relief pain we performed endoscopic sphincterotomies of the pancreatic duct orifice in 1976, 1977 and 1979. Because of relapsing abdominal pain and worsening of the pancreatic duct stenosis we performed two endoscopic balloon dilations of the proximal pancreatic duct at 20 months intervals. These lowered the pancreatoduodenal pressure difference from 40 mm Hg to normal values (below 13 mm Hg) over more than 12 months. Until today only few--less than ten--endoscopic dilations of the pancreatic duct orifice have been reported. A final estimation of this procedure is premature. However our case should stimulate other groups to consider this new form of therapy in selected patients with chronic pancreatitis and marked stenosis of the pancreatic duct.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1983

Serum apolipoprotein AI synthesis in rat hepatocytes and its secretion as proform.

Rat hepatocytes in monolayer or suspension culture synthesize serum lipoprotein AI. It is secreted into the serum-free culture medium. Synthesis and secretion processes were studied in the presence of radiolabelled amino acids. The synthesis product of the hepatocytes and the secretion product from the medium were isolated by immunoprecipitation with a mono-specific rabbit antiserum against rat apolipoprotein AI. The intracellular and secreted products were homogeneous and identical in polyacrylamide gel electrophoresis but had reduced electrophoretic mobility as compared to native apolipoprotein AI. They were submitted to automated Edman degradation. They were present in their proform, the N-terminus of which is extended by a hexapeptide. In the presence of rat serum the proform is proteolytically transformed into the mature form of apolipoprotein AI.

Amino Acid Sequence↗
PubMed1983

A serum proteinase converts proapolipoprotein AI secreted by rat hepatocytes to the mature apolipoprotein.

Apolipoprotein AI integrated into the high-density lipoprotein particle in serum was synthesized in the rat hepatocyte in the presence of radiolabelled amino acids and isolated from the cells in primary culture (suspension) as its proform, with the N-terminus extended by a hexapeptide segment. The primary secretion product is this proform which is only further proteolytically processed in the presence of the serum fraction with density higher than 1.21 g/ml. The secretion product and the proteolytically converted product were characterized by Edman degradation of their respective amino-acid sequences after radiolabelling with [3H]valine and [3H]phenylalanine, the positions of which are well established in the preproform and in the N-terminus of mature rat apolipoprotein AI. The products from the lysed cells and their culture medium were purified by immunoprecipitation, sodium dodecyl sulfate gradient gel electrophoresis and subsequent electroelution of the apo AI band. The proform sediments associated with a particle of density 1.16-1.20 g/ml. The serum proteinase which is inhibited by phenylmethanesulfonyl fluoride, but not by sulfhydryl reagents, is presumably a serine proteinase.

Animals↗
PubMed1981

Autonomous cortisol secretion by a metastatic Leydig cell carcinoma associated with Klinefelter's syndrome.

We present the case of a 39-year-old man with Klinefelter's syndrome and a metastatic Leydig cell carcinoma in whom autonomous cortisol production induced by the interstitial cell tumor was found. Apart from the Cushing's syndrome the endocrine activity of the tumor was demonstrated by the secretion of estradiol, estrone, alkaline phosphatase, and testosterone. This is, to our knowledge, the first description of a Cushing's syndrome not caused via ACTH production but directly induced by ectopic steroid production. While being resistent to chemotherapy and radiation, the tumor responded favorably to treatment with o,p'-DDD. The reduction of tumor size was accompanied by a continuous decrease of serum markers. The etiology of the tumor is discussed in the light of the hormonal derangement caused by the genetic abnormality of Klinefelter's syndrome.

Adult↗
PubMed1978

The formation of contacts between HeLa cells. Directed mutual outgrowth of cell surface protrusions.

The contacting behavior of HeLa cells in subconfluent monolayer cultures has been studied by phase contrast and scanning electron microscopy. We present further evidence that cells separated from each other by a cell-free space up to 20 micron width can simultaneously form directed and mutual protrusions against each other. A statistical analysis demonstrated that in more than half of the possible contact events a reciprocal outgrowth of cell surface protrusions had occurred. This suggests that contact formation is not just a random process, but may be influenced by so far unrecognized factors.

Cells, Cultured↗