[An Experimental Set-Up for Navigated-Contrast-Agent and Radiation Sparing Endovascular Aortic Repair (Nav-CARS EVAR)]. / Ein Prototyp für die navigierte Implantation von Aortenstentprothesen zur Reduzierung der Kontrastmittel- und Strahlenbelastung: Das Nav-CARS-EVAR-Konzept (Navigated-Contrast-Agent and Radiation Sparing Endovascular Aortic Repair).

INTRODUCTION: Over the last decade endovascular stenting of aortic aneurysm (EVAR) has been developed from single centre experiences to a standard procedure. With increasing clinical expertise and medical technology advances treatment of even complex aneurysms are feasible by endovascular methods. One integral part for the success of this minimally invasive procedure is innovative and improved vascular imaging to generate exact measurements and correct placement of stent prosthesis. One of the greatest difficulty in learning and performing this endovascular therapy is the fact that the three-dimensional vascular tree has to be overlaid with the two-dimensional angiographic scene by the vascular surgeon. MATERIAL AND METHODS: We report the development of real-time navigation software, which allows a three-dimensional endoluminal view of the vascular system during an EVAR procedure in patients with infrarenal aortic aneurysm. We used the preoperative planning CT angiography for three-dimensional reconstruction of aortic anatomy by volume-rendered segmentation. At the beginning of the intervention the relevant landmarks are matched in real-time with the two-dimensional angiographic scene. During the intervention the software continously registers the position of the guide-wire or the stent. An additional 3D-screen shows the generated endoluminal view during the whole intervention in real-time. RESULTS: We examined the combination of hardware and software components including complex image registration and fibre optic sensor technology (fibre-bragg navigation) with integration in stent graft introducer sheaths using patient-specific vascular phantoms in an experimental setting. From a technical point of view the feasibility of fibre-Bragg navigation has been proven in our experimental setting with patient-based vascular models. Three-dimensional preoperative planning including registration and simulation of virtual angioscopy in real time are realised. CONCLUSION: The aim of the Nav-CARS-EVAR concept is reduction of contrast medium and radiation dose by a three-dimensional navigation during the EVAR procedure. To implement fibre-Bragg navigation further experimental studies are necessary to verify accuracy before clinical application.

Temperature effects in tuning fork enhanced interferometric photoacoustic spectroscopy.

Temperature dependent measurements with a compact fiber coupled sensor for trace gas detection in the near-infrared based on tuning fork enhanced interferometric photoacoustic spectroscopy are presented. The temperature effects on the sensor have been investigated in a range from T = -41 °C to T = 107 °C, in particular the influence on the resonance frequency and the Q-factor of the micro tuning fork. The refined sensor head contains a combination of a silicon tuning fork and an acoustic off-beam resonator and permits methane detection with a detection limit of S = (3.85 ± 0.01) ppm. The functional capability of a numerical model for the optimization of acoustic off-beam resonators in COMSOL Multiphysics® is presented.

Difference Frequency Generation in AgGaS(2): Sellmeier and Temperature-Dispersion Equations.

Two single-mode diode lasers and AgGaS(2) as a nonlinear medium are applied for difference frequency generation (DFG) in the mid-infrared spectral range between 4.9 and 6.5 mum. Phase matching is achieved by either temperature tuning or angle tuning of the crystal. Experimentally measured sets of input wavelengths lambda(s) and lambda(p), the resulting DFG wavelength lambda(i), and corresponding phase-matching temperatures or angles are compared with the calculated values derived by use of different Sellmeier equations and coefficients and temperature-dispersion equations dn/dT. Our results show that only specific combinations of previously published Sellmeier equations, coefficients, and temperature-dispersion equations are suitable for exact calculations of phase-matching parameters. These combinations reproduce our experimentally obtained phase-matching temperatures and angles with an accuracy of better than 5% and are therefore of fundamental interest for the design of a mid-infrared DFG spectrometer with AgGaS(2) as a nonlinear medium.

Widely Tunable Continuous-Wave Mid-Infrared Laser Source Based on Difference-Frequency Generation in AgGaS(2).

We demonstrate difference-frequency generation in the 6.8-12.5-mum range by mixing two high-power single-frequency laser diodes in a type II AgGaS(2) crystal. This compact all-solid-state scheme provides maximum output powers that exceed 1 muW and permits continuous adjustment-free scans larger than 2 cm(-1) across the entire tuning range.

Time-resolved fluorescence spectroscopy of a hematoporphyrin derivative used for photodynamic therapy of cancer.

Photodynamic therapy (PDT) is a treatment modality for malignancies that, uses the accumulation of a photosensitizer in tumor tissue and a subsequent laser light irradiation to selectively destroy tumor cells. Usually PDT is carried out with a hematoporphyrin derivative (HPD) as photosensitizer. Fluorescence characteristics of the HPD Photosan-3 were determined at different concentrations with time-resolved fluorescence spectroscopy. Photosan-3 showed a concentration dependent fluorescence with one fluorescence decay time below a concentration of 10 micrograms/ml, two or three decay times at 50 and 100 micrograms/ml Photosan-3 respectively. These findings confirm results of former studies on other HPD that aggregates and dimers are probably more responsible for the photodynamic effect than monomers.

Laser-based detection of PAHs and BTXE-aromatics in oil polluted soil samples.

Time-resolved laser-induced fluorescence spectroscopy and fiber optics are applied for the detection of aromatic hydrocarbons in oil contaminated water and soil samples. Time-integrated data accumulation of fluorescence intensities in an "early" and in a "late" time window with respect to the exciting laser pulse simplifies the method in such a way that it becomes very attractive for practical applications. For ultraviolet laser excitation at 337 nm and recording fluorescence signals at 400 nm, typical detection limits of the present set-up are 0.5 mg engine oil/L in water and 5 mg engine oil/kg in soil. A discrimination between BTXE-aromatics and PAHs in oil polluted soil or water samples is possible, when more than one laser wavelength in the ultraviolet is used for the excitation. The possibilities for a thermal discrimination between different aromatics are also discussed.

Helioferins; novel antifungal lipopeptides from Mycogone rosea: screening, isolation, structures and biological properties.

Helioferins A and B were detected as novel aminolipopeptides in cultures of Mycogone rosea DSM 8822 in the course of a screening for mediators of helianthate anion transfer from aqueous to toluene phases. Their structures as novel antibiotics and cytotoxic agents were elucidated by mass spectrometry and NMR spectroscopic methods. Antimicrobial activity was estimated against Candida albicans and Gram-positive bacteria including Mycobacterium spp.

Fiber-optic laser-induced fluorescence probe for the detection of environmental pollutants.

Laser-induced fluorescence (LIF) spectroscopy in combination with fiber optics is shown to be a powerful tool for qualitative and quantitative diagnostics of environmental pollutants in water and soil. Timeintegrated data accumulation of the LIF signals in early and late time windows with respect to the excitation pulse simplifies the method so that it becomes attractive for practical applications. Results from field measurements are reported, as oil contaminations under a gas station and in an industrial sewer system are investigated. A KrF-excimer laser and a hydrogen Raman shifter can be applied for multiwavelength excitation. This allows a discrimination between benzene, toluene, xylene, and ethylbenzene aromatics and polycyclic aromatic hydrocarbon molecules in the samples under investigation. For a rough theoretical approach, a computer simulation is developed to describe the experimental results.

Lymphocytopenia and occupational exposures among pattern and model makers.

OBJECTIVES: The study was performed to examine the relationship between a high prevalence of lymphocytopenia observed during a cancer screening program for pattern and model makers, who produce industrial prototypes and patterns, and 15 occupational exposures. METHODS: The cases (N = 83) were workers with lymphocyte counts of less than 1000, while the referents (N = 529) had counts of 1500 or higher. Exposures at the current workplace, and at up to 19 previous pattern and model shops, were assessed with the use of a questionnaire. RESULTS: Elevated risks were associated with exposure to epoxy resins [odds ratio (OR) 1.94, 95% confidence interval (95% CI) 1.02-3.70) and plastic dusts (OR 2.60, 95% CI 1.19-5.68) after adjustment for age and smoking status. No clear associations were found with duration of exposure or percentage of time potentially exposed. Although the results were based upon small numbers, epoxy resins and wood dust displayed the most consistent relationships in an analysis of changes in lymphocyte count and exposure status over time. CONCLUSION: While firm conclusions cannot be drawn, the strongest associations observed in this study were for exposure to epoxy resins.

[Anthracycline derivatives as photosensitizing agents in photodynamic laser therapy: an in vitro study with squamous epithelial cancer cells of the mouth cavity]. / Anthracyclinderivate als Photosensibilisatoren in der photodynamischen Lasertherapie: Eine In-vitro-Untersuchung an Plattenepithelkarzinomzellen der Mundhöhle.

Photodynamic laser therapy performed with hematoporphyrin derivatives has become increasingly important in the treatment of well-defined tumors in superficial sites. Limitations of this procedure result from the side effects of hematoporphyrin derivatives. In searching for possible alternatives to the usual photosensitizing agents, we studied the cytostatic drugs adriamycin and epirubicin. In order to evaluate the photodynamic effects of these agents we conducted in vitro studies on isolated cells from a squamous cell carcinoma of the oral cavity. The light source employed was an argon laser with wavelengths at 488/514 nm. Comparison of the cytostatic effect achieved by these anthracycline derivatives with and without laser light treatment showed a pronounced photodynamic effect. These results may herald new photodynamic therapeutic modalities.

Pathologist agreement in the interpretation of colorectal polyps.

Practicing physicians commonly perform flexible sigmoidoscopy in their offices. Polyploid lesions are frequently biopsied and sent to community hospitals for pathological interpretation. The pathologist's opinion often determines the course of medical follow-up for the patient, especially in cases in which early malignancy is suspected. This paper addresses the agreement of community-based pathologists regarding the interpretation of colorectal polyp pathology. Ten pathological slide sections were sent to 22 different community-based pathologists in southeast Michigan. These pathologists were asked to record their diagnosis of the specific histologies represented in each of the slides. The results indicated a high level of agreement of histologies in the dichotomous categories of hyperplasia versus adenoma. However, there was considerable disagreement on the presence of moderate or severe atypia. The results of this study indicate that clinicians performing biopsies on patients at risk for colorectal cancer should be aware of the potential for diagnostic variability among pathologists, and should plan follow-up strategies which may include seeking second pathological opinions when a significant patient management decision must be made.

Temperature tuned distributed feedback dye laser with high repetition rate.

A pulsed subnanosecond laser system is described which is tunable over the spectral range from 450 to 650 nm with a bandwidth of ~0.006 nm and can be operated with a repetition rate of up to 200 Hz. It consists of a mirror tuned distributed feedback dye laser which is directly pumped by a XeCl excimer laser. Fine tuning and accurate stabilization of the dye laser wavelength are performed by electronically controlling the temperature of the dye liquid. The long-time stability of the laser wavelength is 0.0028 nm; this is achieved by a novel mechanical and electronic arrangement.

Studies on the biotransformation of the progestagen dienogest in the rabbit.

Following administration of 14 alpha, 15 alpha-3H-Dienogest (STS 557, 17 alpha-cyanomethyl-17 beta-hydroxy-4, 9-estradien-3-one) to female rabbits, extracts from urine, bile and plasma were separated by means of HPLC. Urinary and biliary metabolites are characterized by patterns of high complexity. From the mass spectra and UV absorption data of the urinary Dienogest metabolites a variety of biotransformation reactions has been derived like: hydroxylation in different positions of the Dienogest molecule, among these the 11-position; reduction of the 3-oxo group to 3-hydroxy; introduction of 2 and 4 hydrogen atoms; aromatization of ring A; transformation of 17 alpha-CH2CN to CH2OH, and formation of compounds with a 5(10), 9(11)-diene structure. Some of these reactions occur simultaneously resulting in a very complicated metabolite spectrum. Possibly the multiple effects of Dienogest established in animals are partially caused by metabolites.

Androsta-4,16-diene-3,6-dione: an unknown member among the smelling androst-16-enes.

The synthesis of a still-unknown member of the physiologically interesting 16-unsaturated C19 steroids - androsta-4,16-diene-3,6-dione - is described. The spectroscopic data of the new compound are reported.