[Medical tourism and travel - an interdisciplinary approach]. / Medizintourismus und Medizinreisen - eine inter-disziplinäre Betrachtung.

BACKGROUND: Medical tourism (or medical travel, international patient service, cross-border or global health care) is a new current phenomenon with increasing relevance for the two disciplines of medicine and tourism. Both sides hope to improve their reputation and image, as well as to increase their revenues and rate of employment; furthermore, they want to provide better care and service for patients and tourists: Medical tourism can close the gap of the health care system at home, providing better quality, quicker access and cheaper procedures abroad, also with treatments, not - legally - available in the sending country. For the tourism sector it broadens the variety of tourism products and supply of the host country and combines medical treatments and recovery with an attractive stay in a tourism destination for patients and their companions. But in spite of all popularity of this new type of tourism and treatment, there is quite a lack of theory and academic analysis. METHODS: This article outlines the status quo of scientific research both from a medical and tourism point of view. This interdisciplinary method of approach is based mainly on a state-of-the art review of the current literature. CONCLUSIONS: There is a great need for more scientific research in the field of medical tourism, based on the common knowledge of both disciplines tourism and medicine. First there is neither an internationally agreed definition nor a common methodology for data collection. So the real impact of touristic and medical services both for the source and for the receiving countries is un-known and imprecise. Second the internal processes of the health system have to be adapted to the needs of international patients, e. g., medical fee schedule, billing, language, inter-cultural qualifications of the staff. Moreover the whole service chain has to be taken into account, especially the pre- and post-processes, which mostly start or end abroad. Here quality standards as well as accreditations are current issues. Furthermore, several sociocultural impacts need to be analysed, such as making health care less affordable for local patients and/or moral and ethical concerns about certain treatment methods. Another area concerns the legal questions of risk, liability and malpractice.

Photoelectron spectroscopy on thin films of extended zinc porphyrazines.

Photoemission measurements were performed on a series of stepwise benzoannelated zinc porphyrazine molecules in thin films. The electronic structure of tert-butyl-substituted zinc tetraazaporphyrin, phthalocyanine, and naphthalocyanine is investigated using mainly EUV synchrotron radiation. A detailed analysis of the zinc satellites in the spectra of the valence region is performed in an attempt to infer the effect of ligand size extension on the metal-ligand interactions. No differences in the character of the bond between zinc and ligand were detected as a function of ligand size. The results are compared with those for the respective metal-free and copper-containing molecules.

Femtosecond two-photon excited fluorescence of melanin.

Fluorescence of synthetic melanin in dimethyl sulfoxide has been excited by two-photon absorption at 800 nm, using 120 fs pulses with photon flux densities > or = 10(27) cm-2 s-1. The shortest main component of the three-exponential decay of fluorescence is 200 +/- 2 ps. The overall spectral shape is red-shifted with respect to the 400 nm excited fluorescence. Two-photon excited melanin fluorescence also has been measured from excised samples of healthy human skin tissue. Because of the selectivity of melanin excitation via resonant two-photon absorption, it is hypothesized that fluorescence excited in this way may yield information on malignant transformation.

Spectroscopic properties of potential sensitizers for new photodynamic therapy start mechanisms via two-step excited electronic states.

Three substituted tetraazaporphyrins, octa-(4-tert-butylphenyl)-tetrapyrazinoporphyrazine, tetra-(4-tert-butyl)phthalocyanine and tetra-(4-tert-butyl)phthalocyanatomagnesium(t4-PcMg), were spectroscopically checked in solutions and liposomes with respect to suitability as potential sensitizers of a possible new start mechanism for photodynamic therapy (PDT) from a stepwise excited higher singlet state. This PDT start mechanism was recently proposed to overcome the problem of O2 (1delta2)-caused cutaneous phototoxicity in PDT. By means of absorption and fluorescence measurements as well as nonlinear absorption investigation, transient spectroscopy and lasing experiments, compound t4-PcMg was found to have the most appropriate properties: Based on a high fluorescence quantum yield (phiF1 = 0.84) and a very low crossing to the triplet (phiISC = 0.05), two higher excited states can be effectively populated both by two stepwise absorption transitions at 674nm consecutive absorption transitions at 684 and and 710 nm. Moreover, t4-PcMg incorporates into liposomes very well with spectroscopic properties similar to those in solution.

Photophysical properties and photodynamic activity in vivo of some tetrapyrroles.

Some of the photophysical properties (stationary absorbance and fluorescence, fluorescence decay times and singlet oxygen quantum yields) of pheophorbide a, metal-free, ClAl-, Cu- and Mg-t-butyl-substituted phthalocyanines, metal-free, ClAl- and Cu-t-butyl-substituted naphthalocyanines and of a number of tetraphenylporphyrins (5,10,15,20-tetraphenylporphyrin, 5,10,15,20-tetra(m-hydroxyphenyl)porphyrin, 5,10,15,20-tetra(p-hydroxyphenyl)porphyrin) have been studied in comparison with hematoporphyrin IX in order to select potent photosensitizers for the photodynamic treatment of cancer. The photodynamic activity of these compounds was investigated using Lewis lung carcinoma in mice. As a consequence of the photophysical parameters (relatively short singlet state lifetimes, and high singlet oxygen quantum yields) the photodynamic activities of pheophorbide a, t-butyl-substituted ClAl-phthalocyanine and ClAl-naphthalocyanine were selected for study in greater detail. Under the conditions employed in the present study, pheophorbide a was found to be the most effective sensitizer, as judged from its strong absorption at the excitation wavelength as compared with the hematoporphyrin derivative and greater singlet oxygen quantum yield relative to the phthalocyanines and naphthalocyanines. The photodynamic activity was observed to be strongly dependent on the photophysical parameters of the compounds. The primary mechanism underlying the photodynamic activity of these sensitizers probably consists of energy transfer from the lowest triplet state of the dyes to molecular oxygen, resulting in the formation of singlet oxygen (type II of photosensitization).