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Biomedical subjects

E Keiditsch

Publications and source records attributed to E Keiditsch.

At least 37 records · Page 2Linked to original sources
PubMed1984

[Neodymium YAG laser in clinical urology. Current status and clinical experiences].

Of all the lasers available for medical applications only the Neodymium-YAG laser has been retained with a clear indication for open and endoscopic tumor destruction in urology. This is due to the biophysical properties of this laser. The main indications for Neodymium-YAG laser application are benign and malignant tumors of the glans penis and the penis shaft as well as multiple small tumors distributed over the urethra and bladder mucosa. But tumors of the ureter and renal pelvis can also be destroyed endoscopically with the laser. The advantages of Neodymium-YAG laser application are: the great radicality of the contact-free tumor destruction coupled with closure of the blood and lymphatic vessels of the tumor, no hemorrhages, no anesthesia, only conscious sedation, and above all, short operation times that make the procedure suitable for use in outpatients.

Adult↗
PubMed1984

Interception of lymphatic drainage by Nd:YAG laser irradiation in rat urinary bladder.

Lymphatic drainage can be demonstrated by colloidal indian ink injection. A small intramural indian ink spot in the bladder dome is separated from the rest of the rat urinary bladder by encircling transmural Neodymium-YAG (Nd:YAG) laser irradiation. In untreated animals there is an ink flow via the lymphatic vessels to the regional lymph nodes within several hours. In treated animals, after laser irradiation, the indian ink remains in the bladder dome and a penetration of the irradiated area cannot be found by macroscopic and histologic examination. Indian ink will be found in the regional lymph nodes after the ninth day of absorption of the coagulation necrosis and recanalisation of the intercepted lymphatics. Evidence for the interception of the lymphatic drainage is demonstrated by the distinctly delayed ink flow and the injected ink's remaining in the irradiated area. From this, we conclude that Nd:YAG laser irradiation is especially suitable for tumor coagulation, since simultaneous interception of lymphatic drainage will inhibit the spreading of tumor cells.

Animals↗
PubMed1983

[Destruction of ureteral tumors with the neodymium-YAG laser. A new, organ-preserving surgical procedure].

Only the neodymium-YAG laser is suitable for destroying tumors endoscopically, because it shows a very high transmission through water and a slight absorption in the tissue. It means scattering becomes important and leads to a homogeneous and uniform distribution of the radiation in the tissue producing a deep thermal effect. An examination of a section through a bladder wall under light microscope after neodymium-YAG laser irradiation shows a layered, sharply delimited coagulation necrosis that extends to all of the bladder wall layers and reaches the outermost zones. In this way it is possible to destroy not only the exophytic part of a tumor but also the tumor base in the tissue. Since 1976 we destroyed more than 4000 bladder tumors by laser application. For tumors on the ureter or kidney pelvis a special endoscope, described by Perez-Castro Ellendt and modified by us, can be used, if it is not possible to perform a conventional operation. It is reported about four cases of distal ureter tumors (GI-II) in patients who had refused an operation for removing the tumor bearing ureter segments. Now, for more than one and half a year all patients are free of tumors and the irradiated ureters show a good function. This novel procedure is not for routine, but for high risk patients or patients, who refuse an open operation.

Aged↗
PubMed1983

Transurethral laser coagulation for treatment of urinary bladder tumors.

Owing to the biophysical properties involved, the Nd:YAG laser is most suited for coagulation of even inhomogeneous tissue. We determined the optimal laser parameters for therapy of urinary bladder tumors. Deep homogeneous necroses can be obtained without perforation risk of the bladder wall, and the procedure does not cause dangerous damage to the intestinal loops. We have studied animal experiments by close examination and systematic inquiry, and thus we were able to determine sufficient laser parameters in dependence on tissue thickness. Clinical studies verified these results for living human tissue. After some years of clinical use of the Nd:YAG laser we can make the first statistical statements.

Fiber Optic Technology↗
PubMed1983

[Possibilities of immunologic management of Brown-Pearce carcinoma in rabbits].

The efficacy of the active specific immunotherapy and immune prophylaxis against the Brown Pearce carcinoma in rabbits was tested. The tumor cells taken as antigens were either untreated or treated with Mitomycin C combined or not with vibrio-cholerae-neuraminidase. The immune prophylaxis using tumor cells prepared this way proved to be very effective. In contrast, immunotherapy of rabbits with tumors was not effective, even when immunization was started directly after transplantation. Possible mechanisms were analyzed in-vitro and in-vivo assays. The cellular reactivity of sensitized spleen cells was positive, the humoral reaction was weaker. This kind of reaction could only be demonstrated with tumor cells pretreated with vibrio-cholerae-neuraminidase. The findings shall only be discussed with respect to the possible causes of ineffective immunotherapy.

Animals↗
PubMed1983

Controlled bipolar high-frequency coagulation for transurethral application: a new method for the destruction of urinary bladder tumors.

The coagulation of small bladder papillomas or of the resection base after transurethral resection by unipolar high-frequency current has turned out not to be sufficiently radical so far. There is no definite and reproducible correlation between the achieved biological effect. Bipolar high-frequency current produces the desired necrosis in the deeper layers of tissue. When providing the high-frequency generator with a new experimental automatic control equipment, reproducible deep and homogeneous necrosis of the tissue can be achieved without taking a great deal of time. Moreover, adherence of the probe and carbonization are prevented. First, the experiments had been carried out in vitro on livers of cattle and secondly, in vivo on canine livers. By the conventional unipolar high-frequency coagulation a reproducible and homogeneous necrosis cannot be achieved. With the regulated high-frequency coagulation, however, we are able to produce homogeneous tissue necroses up to a depth of 7 mm, the extension of which can definitely be assigned to the adjusted technical parameters. The electrodes do not adhere, since carbonization does not occur because of the automatic control. Premature interruption of the coagulation process, even if the generator is adjusted too high by mistake, can be considered a further advantage of this protective switch. A first clinical experience is reported.

Adult↗
PubMed1982

Various effects of the CO2-, the neodymium-YAG-, and the argon-laser irradiation on bladder tissue.

Application of lasers as cutting or coagulation instruments is based on the conversion of light energy into heat in the irradiated tissue. The extent and degree of the thermal action depends on the beam geometry and the energy of the incident light, as well as on the optic and thermal properties of this tissue. The extinction behavior in the tissue differs for the various laser systems employed in medicine. A comparison of the effects on bladder tissue of rats and rabbits is made with Neodymium-YAG laser and the argon and CO2 lasers to demonstrate the advantages of the Neodymium-YAG laser, especially for the therapeutic irradiation of bladder tumors.

Animals↗
PubMed1981

Endoscopic Neodymium-YAG laser application for destroying bladder tumors.

302 bladder tumors to a size of a thumb tip were treated with a Nd: YAG laser. 196 large bladder tumors were removed by transurethral resection combined with laser irradiation 1 week later. In all cases tumors were classified as pTA to pT3a, No, Mo tumors. 8 weeks after treatment we found local recurrences in 9% using the rigid laser endoscopes. On the contrary, the local recurrence was 2.1% using laser endoscope with modified Albarran insert. In proven cases the Nd:YAG laser application is an effective and careful procedure to destroy bladder tumors.

Humans↗
PubMed1981

[Histological changes following endovesical neodymium-YAG-laser irradiation (author's transl)].

Experimental animal research was used to compare the coagulatory qualities of the argon laser and the Neodymium-YAG laser to results obtained through electrocoagulation. The argon laser effects a necrosis near the urinary bladder wall surface, and when the energy density is increased, it may ablate the tissue to the point of perforation. In contrast, the Neodymium-YAG laser effects a bandshaped necrosis that penetrates all layers of the urinary bladder wall without primarily resulting in an ablation of tissue. Electrocoagulation results in irregularly demarcated necroses of varying depths, which can be explained by the uncontrolled flow of the high-frequency currents according to the paths of least resistance. The Neodymium-YAG laser is the one most suited for transmural coagulation of defined areas within the urinary bladder wall due to the even spread of its thermal energy that is independent of the affected tissue structure, as well as to its deep coagulatory qualities which in turn are due to the laser's minimal tissue absorption. The Neodymium-YAG laser allows the setting of reproduceable, sharply demarcated necroses into the bladder wall with an ensuing complete destruction of all wall layers. The wall framework within the necrotic area, however, remains intact, so that the danger of perforation is kept at a minimum.

Animals↗
PubMed1981

[Dosimetry of the neodymium-YAG laser endovesical irradiation of bladder tumors. Animal experiments (author's transl)].

Therapy of urinary bladder tumors with the aid of the Neodymium-YAG-laser is improved by two following demands. A homogeneous, deep necrosis must be obtained for the tumor cells to be devitalised completely, and neighbouring organs must be protected adequately. Both depth and shape of the necrosis were determined on liver tissue at different conditions, e.g. laser application with air, water and various time/power ratios. Measurements of temperature profiles at the bladder back wall reveal that the parameters necessary for sufficient transmural destruction of bladder tumors do not affect neighbouring organs. In clinical application it is not necessary to control temperatures occurring at the bladder wall during irradiation by means of temperature probes. It is sufficient to adjust the dosis of laser on the basis of superficial, visual discoloration. Carbonisation should be avoided by all means. Comparable effects were obtained by clinical application of data obtained during animal experimentation.

Animals↗