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  • 1
    Electronic Resource
    Electronic Resource
    Fluorescence detection and photodynamic treatment of photosensitized tumours in special consideration of urology (1990)
    Springer
    Lasers in medical science 5 (1990), S. 207-212 
    Details
    ISSN: 1435-604X
    Keywords: Bladder tumour ; Diagnosis ; Fluorescence ; Photodynamic therapy ; Photosensitization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Most methods of modern laser tumour therapy are physically based on the conversion of light to heat. Recently tumours have also been treated using ionizing processes for tissue ablation. Photodynamic laser therapy (PDT), however, involves light-induced non-thermal biochemical processes and the use of a photosensitizer. Several drugs are known to be stored selectively in tumours after systemic application. This transient marking can be used for diagnostic and therapeutic procedures. The marker most commonly used is dihaematoporphyrin ether/ester (DHE) intravenously injected at doses of 0.2–3.0 mg/kg bodyweight for diagnosis and therapy, respectively. The corresponding clearance intervals after injection of DHE range from 3–48 h to 25–75 h. Detection of photosensitized tumours might offer great advantages. The highly sensitive two-wavelength laser excitation method with computerized fluorescence imaging recently has been transferred to the hospital for clinical tests. Photoinduced production of singlet oxygen is claimed to be the initial process which leads to later tumour destruction and therapy. PDT has been applied to 20 patients suffering from superficial tumours (TIS GII–III) recurred after application of other treatments. The results after PDT were evaluated by three-monthly check-ups (endoscopy, cytology, bladder mapping, renal ultrasonography) as well as by computed tomography (CT) examination at 8–13 month intervals. In six patients treated by PDT no tumour recurrence has been found over the whole observation period of up to 5 years. Four patients have remained free of tumour (12 and 14 months) after repeated transurethral resection (TUR) and Nd-YAG laser therapy following PDT. Due to an initial application of insufficient irradiation four patients required a second PDT. In one patient a circumscribed dysplasia appeared at the left ostium 26 months following PDT and was treated successfully by means of thermal Nd-YAG laser irradiation following TUR. In six patients slight mucosal atypia persisted for a period of at least 2.5 years. One cystectomy had to be performed because of bladder shrinkage. The dissected bladder, however, was free of tumour. These preliminary results suggest that PDT is justified in patients who are in a worst-case situation with cystectomy recommended in case of recurrent superficial TIS bladder carcinoma and indicate the future potential of photodynamic therapy of tumours. Homogeneous irradiation of the area to be treated and a reliable light dosimetry are prerequisites for an effective tumour therapy. Standard instruments for a routine application do not exist, but are under development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031384
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  • 2
    Electronic Resource
    Electronic Resource
    Laser-assisted fluorescence detection of plaque (1991)
    Springer
    Lasers in medical science 6 (1991), S. 289-296 
    Details
    ISSN: 1435-604X
    Keywords: Atherosclerosis ; Dihaematoporphyrin ether/ester, DHE ; Haematoporphyrin derivative, HPD ; Laser angioplasty ; Laser-induced fluorescence ; Plaque
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Selective fluorescence-marking of plaque offers new possibilities in cardiovascular diagnosis and therapy. Angioscopic investigations and spectrometry-assisted laser angioplasty will be simplified and more effective as compared with methods of today. It might help to make laser angioplasty a further promising interventional method to overcome, at least partially, the problems caused by atheromatous or atherosclerotic changes in the cardiovascular system. Fluorescence detection and imaging of markers is usually limited by the intrinsic fluorescence of tissue. Optical differential methods in combination with two-wavelength laser excitation and computer-assisted image processing, however, allow for discrimination of background-related signals and enable plaque detection and imaging at a high contrast. Plaque consists of either fibrotic, lipoid, or calcified depositions and is rather bradytrophic. For that reason in vitro experiments on human specimens post mortem seem to be justified and of clinical evidence. Due to intrinsically different fluorometric properties of plaque and normal vascular tissue imaging of marker-free plaque areas is possible. Additionally the specimens have been incubated with a haematoporphyrin-containing fluorescence marker at concentrations of 10–40μg ml−1 and incubation times of 60 min in order to obtain a corresponding increase in contrast. Lipoid depositions show the highest contrast because of lipophilic properties of the marker, while fibrotic and calcified plaque is slightly less effectively marked. The results, however, so far obtained indicate that fluorescence detection of plaque promises further progress in diagnosis and therapy of cardiovascular diseases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02030882
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  • 3
    Electronic Resource
    Electronic Resource
    A high-sensitivity laser microprobe mass analyzer (1975)
    Springer
    Applied physics 8 (1975), S. 341-348 
    Details
    ISSN: 1432-0630
    Keywords: Laser microprobe ; Micro-mass analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A laser microprobe mass analyzer has been developed. It is intended for application in biomedical and physiological research. A frequency-doubled ruby laser is focussed through an incident light microscope to a spot of minimally 0.5 μm in diameter on a thin section specimen of 0.1–1.5 μm thickness. The microplasma generated from the irradiated volume is analyzed in a time-of-flight mass spectrometer recording the complete spectrum for each shot. From lithium doped epoxy resin (5 ppm by weight), used as an organic standard, 1.4×10−19g or 1.4×104 atoms of the6Li isotope have been detected. This sensitivity corresponds to that of ion microprobes but is at least an order of magnitude higher than obtained with electron probe X-ray microanalyzers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00898368
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  • 4
    Electronic Resource
    Electronic Resource
    Application of fibrin adhesive in the urinary bladder (1987)
    Springer
    Urological research 15 (1987), S. 307-310 
    Details
    ISSN: 1434-0879
    Keywords: Fibrin adhesive ; Hemorrhage of the bladder ; Transurethral hemostasis ; Radiotherpay-damaged urinary bladder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The investigations on rats and pigs showed that the transuretheral haemostasis of the urinary bladder damaged by radiotherapy is possible by means of fibrin adhesion. The spraying procedure has to be carried out by means of a special balloon-catheter in a bladder filled with CO2. During spraying the bladder must be kept constantly free of pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00258202
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  • 5
    Electronic Resource
    Electronic Resource
    Time-resolved investigations of radiophotoluminescence in metaphosphate glass dosimeters (1981)
    Springer
    Applied physics 26 (1981), S. 23-26 
    Details
    ISSN: 1432-0630
    Keywords: 87.60 Mv ; 78.55 Hx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Silver-activated metaphosphate glass samples show a dose-dependent radiophotoluminescence (RPL) after exposure to ionizing radiation. RPL is discriminated from stray light and parasitic luminescence due to the different decay times by use of uv-laser pulse excitation and time-resolved photon detection. A computer controlled single-photon counting system is set up for quantitative evaluation of the RPL signal. A linear relationship between RPL and absorbed dose is proven down to the sub-mGy range. The measuring technique allows glass dosimeters to be applied even at doses corresponding to the environmental radiation incidence per month.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197673
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  • 6
    Electronic Resource
    Electronic Resource
    Is the rise of the action potential of the ranvier node controlled by a paranodal organ? (1974)
    Springer
    Naturwissenschaften 61 (1974), S. 369-370 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00600316
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  • 7
    Electronic Resource
    Electronic Resource
    Irradiation modalities for photodynamic therapy (1989)
    Springer
    Lasers in medical science 4 (1989), S. 159-164 
    Details
    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract For photodynamic therapy of tumors in hollow organs a homogeneous distribution of the applied laser light is desirable but often difficult to be achieved. Different irradiation modalities are compared in this paper. A method for homogenization of light using a layer of a highly backscattering medium deposited on the wall of the organ is described. The homogenization effect is studied theoretically for spherical and cylindrical hollow organs and, in part, compared with experimental results. An irradiation efficiency of more than 90% of the applied light dose is expected, i.e. losses can be reduced to 10% only.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276681
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  • 8
    Electronic Resource
    Electronic Resource
    X-Ray- and catheter-guided intracardial laser photocoagulation of arrhythmogenic substrates (1991)
    Springer
    Lasers in medical science 6 (1991), S. 367-370 
    Details
    ISSN: 1435-604X
    Keywords: Arrhythmia ; Cardiology ; Cardiovascular surgery ; Catheter ; Heart ; Laser ; Mapping ; Photocoagulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Cardiac arrhythmias resistant to drug treatment and correlated to an arrhythmogenic anatomic structure can be treated in several cases by surgical intervention. A further method of treatment is the percutaneous, ECG mapping-guided catheter ablation with either direct current (DC) or radio frequency (RF) ablation of localized arrhythmogenic foci. These methods overcome some complications inherent to open surgery to the heart; DC ablation, however, often induces further arrhythmias or ventricular or auricular fibrillation, while RF ablation shows only little success. In the method presented here disturbing electric effects are avoided by laser photocoagulation via a transcatheter quartz fibre. An electrode/laser catheter recently developed simultaneously allows for a mapping-guided localization of arrhythmogenic substrates and their percutaneous transluminal and intracardial deactivation. An anchoring mechanism at the catheter's tip keeps it in place during the treatment. This mechanism also prevents contact of the quartz fibre to the endomyocardium in order to avoid destruction of the fibre tip due to local overheating of the myocardium. A Nd-YAG laser (wavelength 1.064μm) delivers pulses of 5–10 s and a power of 10–15 W at the tip of a quartz fibre with a core diameter of 400μm. The corresponding parameter or irradiation of the myocardium are power densities of 700–1500 W cm−2 and energy densities of 8–15 kJ cm−2. In dog hearts lesions 2–10 mm in diameter and up to 11 mm in depth were obtained. Simultaneously registered electrocardiograms show that primarily induced arrhythmias lasted only for about 3 min but could not again be observed during the 2–3 months follow-up. Crater formation or perforation of the myocardium always could be avoided by an ECG-controlled laser irradiation. This indicates the safety and efficacy of the laser method for intracardial intervention in arrhythmogenic substrates. Clinical tests have been started recently.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02030895
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