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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Photochemistry and Photobiology B: Biology 4 (1990), S. 363-369 
    ISSN: 1011-1344
    Keywords: Atherosclerosis ; fluorescence ; picosecond laser ; time-resolved spectroscopy ; tissue diagnosis.
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Eighty basal cell carcinomas (BCCs) in 21 patients, 10 lesions of Bowen's disease in three patients, and four lesions of cutaneous T-cell lymphoma in two patients, were treated with photodynamic laser therapy (PDT), using topical application of the haem precursor δ-amino levulinic acid (ALA). The diagnoses were confirmed histologically prior to treatment. Fifty-five of the BCCs were superficial lesions, and 25 were nodular. Of the 80 BCCs, 39 (49%) were located on the trunk, 36 (45%) on the head and neck region, four (15%) on the leg and one on the arm. The two principal locations of the 10 Bowen's disease lesions were the leg (50%) and the trunk (40%). The T-cell lymphoma lesions were located on the shoulder and on the arm. A water-in-oil based cream containing 20% ALA was applied to the lesions, with a margin of about 10–20 mm beyond the visible tumour border, 4–6 h before the laser procedure. During this period of time the highly fluorescent and photodynamically active substance protoporphyrin IX (Pp IX) is synthesized via the haem cycle. Laser-induced fluorescence (LJF) was used for real-time monitoring of the Pp IX distribution in the tumour and in the normal surrounding skin, before and after treatment in all patients. Before laser treatment the Pp IX distribution demonstrated by LJF showed a demarcation between tumour and normal skin of about 15:1 for BCC and Bowen's disease, and 5:1 for T-cell lymphomas. Laser light from a pulsed frequency- doubled Nd: YAG laser pumping a dye laser with light emission at 630 nm was used for the therapy. The power density in the irradiation was kept below 110 mW/cm2, in order to avoid hyperthermal effects. A total energy of 60 J/cm2 was delivered for 10–20 min, depending on the tumour size. A complete response rate of 100% in superficial BCCs and 64% in nodular BCCs occurred after a single laser treatment, and a response rate of 100% was achieved after one additional treatment in the nodular BCCs. In the Bowen's disease lesions a complete response of 90% was obtained with a single treatment. Two of the four T-cell lymphomas resolved completely. The follow-up time was between 6 and 14 months.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary Background Photodynamic therapy (PDT) is a local treatment modality with increasing indications for various malignant and non malignant diseases. The treatment parameters have not yet been optimized as there is a need for a better understanding of the process. The skin is an important target and serves as a good model for monitoring and evaluating the interaction of light with biological tissue. Objectives The tissue perfusion and the temperature of basal cell carcinomas were measured in connection with PDT in order to investigate the biological mechanisms involved. Methods An infrared camera was used during the treatment to measure skin temperature and a laser Doppler perfusion imaging device was used to image the superficial perfusion before and after treatment. Six hours after topical application of 5-aminolaevulinic acid (ALA) or methyl esterified ALA (ALA–ME), 38 basal cell carcinomas were treated using light from a diode laser at 633 nm. Results In the lesions, the perfusion immediately after PDT was similar to that before PDT. One hour after the treatment the perfusion in the lesion was increased 50% compared with before PDT. However, in the skin surrounding the lesions the perfusion was doubled immediately after PDT and was still increasing 1 h after treatment. A temperature increase in the lesions of about 1–3 °C was observed for light fluence rates of 100–150 mW cm−2. In all patients treated, a diffuse temperature increase was visible outside the lesions. In some of the patients, the outlines of the blood vessels surrounding the treated lesions became visible in the thermal images. Measurements of temperature on healthy volunteers not administered photosensitizer, but illuminated with light of the same fluence rate, showed a similar increase in temperature in the illuminated spots. However, no temperature increase was observed outside the illuminated area. No statistically significant differences were found between the measurements on patients treated with ALA and ALA–ME. Conclusions The increased perfusion in the area surrounding the lesions after PDT, as seen by perfusion and temperature measurements, is the result of an inflammatory reaction to the PDT process. However, directly after PDT the perfusion in the lesions was the same as before irradiation. The combination of these observations suggests the presence of local blood stasis during and immediately after the treatment. The temperature measurements showed that the increased temperature was well below the temperature limit of hyperthermal damage. Furthermore, the measurements indicate that the increase in temperature was primarily a consequence of the heat absorbed in the tissue.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background A previously reported randomized clinical trial showed treatment of Bowen's disease using photodynamic therapy (PDT) with topically applied δ-aminolaevulinic acid (ALA) to be at least as effective as cryosurgery and to be associated with fewer adverse effects. Objectives To compare ALA-PDT and cryotherapy in the treatment of histopathologically verified basal cell carcinomas (BCCs) in a non-blinded, prospective phase III clinical trial. Methods One lesion from each of 88 patients was included. The BCCs were divided into superficial and nodular lesions. The follow-up period was restricted to 1 year with close follow-up for the first 3 months. Efficacy was assessed as the recurrence rate 12 months after the first treatment session, verified by histopathology. Tolerability was evaluated as the time of healing, pain and discomfort during and after the treatment, and final cosmetic outcome. Results Histopathologically verified recurrence rates in the two groups were statistically comparable and were 25% (11 of 44) for ALA-PDT and 15% (six of 39) for cryosurgery. However, clinical recurrence rates were only 5% (two of 44) for PDT and 13% (five of 39) for cryosurgery. Additional treatments, usually one, had to be performed in 30% of the lesions in the PDT group. The healing time was considerably shorter and the cosmetic outcome significantly better with PDT. Pain and discomfort during the treatment session and in the following week were low, and were equivalent with the two treatment modalities. Conclusions In terms of efficacy, ALA-PDT is comparable with cryosurgery as a treatment modality for BCCs. Retreatments are more often required with PDT than with cryosurgery. This can easily be performed due to the shorter healing time, less scarring and better cosmetic outcome that follows ALA-PDT.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Laser Doppler perfusion imaging offers a new modality for in vivo monitoring of the superficial blood perfusion in biological tissue. In this study, the superficial blood perfusion of malignant nonmelanoma skin tumours and the surrounding normal skin was measured in conjunction with photodynamic therapy (PDT) using topical ò–aminolaevulinic acid (ALA)–induced protoporphyrin IX as a photosensitizer. The results clearly show that, in contradiction to PDT with the intravenously administered photosensitizer photofrin. no direct vascular damage can be seen. With the topical sensitization the blood perfusion is increased immediately after the treatment irradiation. The increased blood flow is seen up to a week after treatment, in a similiar way as for an inflammatory reaction. Despite this, all basal cell carcinoma and squamous cell carcinoma in situ lesions in this study healed without any sign of residual tumour after the treatment, suggesting an efficient direct tumour cell destruction induced by PDT.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Structural and multidisciplinary optimization 2 (1990), S. 153-162 
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper deals with the classical structural optimization problem of minimizing the weight of a truss structure, subject to constraints on displacements and stresses. Design variables are the cross-section areas of the elements. The main theoretical result presented is that the complete Taylor series expansions of all constraint functions can be explicitly expressed, once the displacements corresponding ton specific load cases have been calculated, wheren = the number of elements. Based on this theoretical result, new explicit approximations of the constraint functions are suggested. These approximations are shown to have some interesting theoretical properties. They also seem to work very well in practice, when included in an optimization scheme.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Structural and multidisciplinary optimization 7 (1994), S. 42-46 
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Compliances, which are measures of “inverse stiffness”, are sometimes used in the objective function, or as constraint functions, in structural optimization. It is known that if compliances are expressed as functions of thickness variablest j, e.g. cross-sectional areas of truss elements, then these functions become convex. In this paper it is shown that if compliances are expressed as functions of reciprocal thickness variablesx j = 1/t j, then these functions become concave. Based on this result, it is further shown that a well-known structural optimization method is globally convergent when applied to minimum weight problems subject to constraints on compliances under multiple load cases.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1440
    Keywords: Leukocyte interferon-α ; Podophyllotoxin ; Human papillomavirus ; Genital warts ; Venereal warts ; Pharmaceutical creams ; Woman
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this double-blind, placebo-controlled, comparative study was to evaluate the specific clinical efficacy and tolerance of human leukocyte interferon-α (2×l06 IU/g) and podophyllotoxin 0.5% incorporated in a hydrophilic cream to cure genital warts. Preselected Asian women (n=60) aged 18–40 years (mean 22.9), with a clinical and biopsy-confirmed diagnosis of genital warts, harboring 322 lesions (mean 5.36) were randomly assigned to three parallel groups to receive one of the two test drugs or placebo. Each patient received a preceded tube (40 g) containing either human leukocyte interferon-α, podophyllotoxin, or identically appearing placebo cream for 3 days' usage. In addition to written instructions, each subject was shown how to apply a minimal amount of trial medication on their lesions thrice daily for 3 consecutive days per week (maximum nine topical applications per week). Patients were examined on a weekly basis, and a cure was considered to be a biopsy-confirmed, total elimination of a lesion. Moreover, patients cured during the study period were spared further therapy, and were requested to return in 16 weeks to monitor for the occurrence of a relapse. The remaining patients' empty tubes were collected, and similarly precoded replacement tubes were given to continue the treatment; a total of 214 tubes were used. The study was scheduled for 16 weeks with 4 weeks of active treatment. Individuals were excluded from the study due to pregnancy, breast feeding, or the receiving of any type of antiviral therapy during the 4 weeks preceding enrollment. Better results were obtained with leukocyte interferon-α cream than with podophyllotoxin both in terms of the number of cured patients (18/20 vs. 12/20, or 90% vs. 60%; P〈0.0285) and the number of eliminated lesions (105/110) vs. 87/108, or 95.5% vs. 80.5%; P〈0.001. In the placebo group 4/20 (20%) patients were cured, indicating lower results. Out of the 60 patients 51 (85%) complained of no drug-related symptomatic side effects. However, the most frequent nonobjective adverse symptoms experienced by the patients were mild tenderness 4/60 (6.6%), burning sensation 3/60 (5%), and transitory increase in body temperature (〉38°C) accompanied by headache and itching 2/60 (3.3%). None of the patients suffering from these side effects elected to discontinue the study. The patients were evaluated for 1 year after the initial visit, and among the 34/60 (56.6%) cured patients two had a relapse after 9 months. In conclusion, the clinical results of this study demonstrate that leukocyte interferon-α (2×l06 IU/g) is more efficacious than 0.5% podophyllotoxin and placebo in hydrophilic cream, and substantiates that along with mild, nonobjective, transient, localized, adverse symptoms, human leukocyte α-interferon therapy is more effective and better than podophyllotoxin in cream for curing genital warts in women
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1435-604X
    Keywords: Cancer detection ; Fluorescence spectroscopy ; Haematoporphyrin derivative ; Laser excitation ; Phthalocyanine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Several photosensitizers were screened for their tumour-marking ability using laserinduced fluorescence in Wistar/Furth rats bearing subcutaneous adenocarcinomas inoculated in muscle. Of the studied photosensitizers, dihaematoporphyrin ether appeared to exhibit the best tumour-demarcation properties. Polyhaematoporphyrin ester and tetrasulfonated phthalocyanine were almost as good although the fluorescence yield was much lower. Monomeric haematoporphyrin also showed some tumour-marking qualities. By forming fluorescence intensity ratios, information from both the blue and the red spectral regions were used to provide the highest tumour-to-muscle contrast. Two excitation wavelengths were used, of which 337 nm rather than 405 nm excitation light seemed to yield a better tumour demarcation, due to a greater difference in the superimposing autofluorescence between tumour and surrounding tissue. The study included measurements on many inner organs in an attempt to gain a better understanding of the interaction between the drugs and various kinds of tissue.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1435-604X
    Keywords: Autofluorescence ; Laser-induced fluorescence ; Laser-induced breakdown spectroscopy ; Atherosclerosis ; Tissue diagnostics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract We have investigated laser-induced fluorescence frompost mortem human arteries in order to find spectroscopic properties allowing discrimination between normal and atherosclerotic vessel wall. A pulsed nitrogen laser emitting light at a wavelength of 337.1 nm was used as an excitation source. The fluorescence spectrum from 370 to 700 nm was captured and analysed by an optical multichannel analyser. Dimensionless contrast functions were formed by using characteristic spectral features at 390, 415, 480, 580 and 600 nm. All samples were investigated in scans across a region where normal as well as diseased vessel wall appeared. The types of plaque were histopathologically divided into four groups, of which three could be singled out using one or more of our spectroscopic criteria. We also investigated the different layers of the normal and diseased vessel wall in order to determine the various contributions to the fluorescence signal. Furthermore, plasma emission spectra were recorded while ablating the normal as well as the diseased vessel wall with an excimer laser, emitting radiation at 308 nm, thus detecting the change in spectral characteristics during the ablation process down into deeper layers.
    Type of Medium: Electronic Resource
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