Juergen Lademann

Penetration of Titanium Dioxide Microparticles in a Sunscreen Formulation into the Horny Layer and the Follicular Orifice

Coated titanium dioxide (TiO2) microparticles are commonly used as UV filter substances in commercial sunscreen products. The penetration of these microparticles into the horny layer and the orifice of the hair follicle was investigated. The distribution of the microparticles in the horny layer was analyzed using the method of tape stripping in combination with spectroscopic measurements. Deeper layers of the stratum corneum were devoid of TiO2 even after repetitive application of sunscreen preparation when analyzing interfollicular areas. Only in the areas of the pilosebaceous orifices could microparticles be identified. The penetration of TiO2 was investigated in histological skin sections. A biopsy was taken from a skin area from which the horny layer had been removed by tape stripping. In isolated areas, a penetration of coated TiO2 into the open part of the follicle was observed. The amount of TiO2 found in a given follicle was less than 1% of the applied total amount of sunscreens. A penetration of microparticles into viable skin tissue could not be detected.

Diagnostic potential of erythrocytes aggregation and sedimentation measurements in whole blood samples

The membranes of the erythrocytes are covered with different kinds of proteins determining decisively the aggregation and disaggregation properties of erythrocytes. Morbid changes in the human body are reflected by changes in the kind and concentration of these proteins and this way by the aggregation and disaggregation behavior of erythrocytes. Light scattering measurements were used for the investigation of these changes comparing healthy volunteers and patients with different diseases. The whole blood samples were analyzed using a rotating coaxial cylinder system in combination with a special method for data processing. The erythrocyte aggregates were destroyed completely without injuring the cell membranes by shear forces arising during the cylinder rotation. In this paper the results of aggregation and disaggregation analysis of erythrocytes in whole blood samples of healthy volunteers and patients suffering different diseases are presented. The method of erythrocyte aggregation and disaggregation measurements is compared with blood sedimentation measurements.

Investigation of the aggregation and disaggregation properties of erythrocytes by light-scattering measurements

The aggregation and disaggregation behavior of erythrocytes reflects pathological states of the human body. The investigation of the aggregation and disaggregation process of human blood samples by laser spectroscopic measurements is described int he present paper. The whole blood samples were analyzed using a rotating coaxial cylinder system in combination with a special method for data processing. The erythrocyte aggregates were destroyed completely without injuring the cell membranes by shear forces arising during the cylinder rotation. The time behavior of the remission signal during the aggregation process was investigated. The disaggregation process was characterized by the dependence of the remission signal intensity on different applied shear rates.

Investigation of laser-tissue interaction in medicine by means of laser spectroscopic measurements

Toxic and carcinogenic substances were produced during laser application in medicine for the cutting and evaporation of tissue. The laser smoke presents a danger potential for the medical staff and the patients. The laser tissue interaction process was investigated by means of laser spectroscopic measurements which give the possibility of measuring metastable molecular states directly as a prerequisite to understand and to influence fundamental laser tissue interaction processes in order to reduce the amount of harmful chemicals. Highly excited atomic and molecular states and free radicals (CN, OH, C2, CH, CH2) have been detected applying spontaneous and laser induced fluorescence methods. It was found that the formation of harmful substances in the laser plumes can be reduced significantly by optimization of the surrounding gas atmosphere. A high content of oxygen or water in the interaction zone has been found, in agreement with the results of classical and analytical methods, as a suitable way to decrease pollutant emission. The experimental methods and the principal results are applicable not only in laser medicine but in laser material treatment generally.

Keratin-water-NMF interaction as a three layer model in the human stratum corneum using in vivo confocal Raman microscopy

The secondary and tertiary structure of keratin and natural moisturizing factor (NMF) are of great importance regarding the water regulating functions in the stratum corneum (SC). In this in vivo study, the depth-dependent keratin conformation and its relationship to the hydrogen bonding states of water and its content in the SC, are investigated using confocal Raman microscopy. Based on the obtained depth-profiles for the β-sheet/α-helix ratio, the stability of disulphide bonds, the amount of cysteine forming disulphide bonds, the buried/exposed tyrosine and the folding/unfolding states of keratin, a “three layer model” of the SC, regarding the keratin-water-NMF interaction is proposed. At the uppermost layers (30–0% SC depth), the keratin filaments are highly folded, entailing limited water binding sites, and NMF is mostly responsible for binding water. At the intermediate layers (70–30% SC depth), the keratin filaments are unfolded, have the most water binding sites and are prone to swelling. At the bottom layers (100–80% SC depth), the water binding sites are already occupied with water and cannot swell substantially. The hydrogen bonding states of water molecules can only be explained by considering both, the molecular structure of keratin and the contribution of NMF as a holistic system.

Characterization of laser-tissue interaction by laser plume species

Gas chromatography (GC), mass spectrometry (MS), GC/MS technique and standardized methods have been used to investigate harmful chemicals produced during laser treatment of tissue and to find relations between the emitted molecules and interaction processes. It has been found that the emission of carbon monoxide is strongly connected with carbonization. Hydrocyanic acid is well suited to get information on processes, characterizing laser tissue interaction, e.g., plasma behavior. From results obtained by variation of the reaction gas atmosphere (helium, nitrogen oxygen, air) it becomes clear that two processes must be taken into account, oxidation (combustion) and the preferred formation of compounds characterized by the cyano group. It is possible to reduce the amount of emitted hydrocyanic acid drastically working in an oxygen atmosphere. The typical substances arising during laser tissue interaction were compared with the emission obtained by laser treatment of fiber-reinforced plastics, pointing out that the high temperature region (plasma torch) is an important source of the emitted substances.

Dependence of laser plume components on different laser-tissue interaction processes

The simple molecules, water, carbon dioxide, carbon monoxide, and hydrocyanic acid, as well as volatile organic substances have been used to investigate fundamental processes arising during laser tissue interaction. The compounds have been determined by gas chromatography (GC), by gas chromatography in combination with mass spectrometry (GC/MS), and by help of an ion selective electrode. Especially, the dependence of the emitted substances, irradiating porcine tissue (bone, muscle, and liver) with XeCl, TEA CO2, and cw CO2 laser radiation, on different reaction gases are appropriate to obtain information on basic processes. The results demonstrate that oxidation is a process effective in rivalry to the formation of such toxic substances as carbon monoxide, hydrocyanic acid, and styrene as a typical volatile organic compound. The moisture content of tissue is another parameter influencing the interaction processes characteristically. It is possible to reduce the emitted amount of harmful chemicals working in an oxygen containing atmosphere or with a high water content in the reaction zone.

In vivo optical imaging of the viable epidermis around the nailfold capillaries for the assessment of heart failure severity in humans

Heart failure (HF) is among the socially significant diseases, involving over 2% of the adult population in the developed countries. Diagnostics of the HF severity remains complicated due to the absence of specific symptoms and objective criteria. Here, we present an indicator of the HF severity based on the imaging of tissue parameters around the nailfold capillaries. High resolution nailfold video capillaroscopy was performed to determine the perivascular zone (PZ) size around nailfold capillaries, and 2-photon tomography with fluorescence lifetime imaging was used to investigate PZ composition. We found that the size of PZ around the nailfold capillaries strongly correlates with HF severity. Further investigations using 2-photon tomography demonstrated that PZ corresponds to the border of viable epidermis and it was suggested that the PZ size variations were due to the different amounts of interstitial fluid that potentially further translates in clinically significant oedema. The obtained results allow for the development of a quantitative indicator of oedematous syndrome, which can be used in various applications to monitor the dynamics of interstitial fluid retention. We therefore suggest PZ size measured with nailfold video capillaroscopy as a novel quantitative sensitive non-invasive marker of HF severity.

Characterization of laser tissue interaction processes by laser spectroscopic measurements

The specific possibilities of the time-resolved fluorescence spectroscopy have been used to determine in on-line measurements the reactive species arising in the reaction zone during laser tissue interaction. The measured radicals, ions and excited atoms are the basic components for the formation of stable harmful chemicals observed in laser plume and therefore the best parameters for the optimization of the laser tissue interaction process. A water aerosol spray system that reduces the emission of the harmful components in the laser plume is described. The effectiveness of this arrangement depends strongly on the water concentration in the interaction zone. The determination of C2, CH and CN radicals which lead to the formation of harmful substances and the OH and O species which characterize the water content of the tissue by laser spectroscopic measurements gives the possibility to optimize the interaction process.

Optimization of tissue interaction in electrosurgery

The number of sparks per time window between a scalpel electrode and tissue is a measure of the electrosurgical cutting ability with a strong dependency on the electrical power dissipation. This parameter used as controlled variable in an appropriate circuit allows controlling electrosurgical treatments with best cutting quality at any kind of tissue. It is presented the effect of this control unit with regard to therapeutic aspects and smoke emission. Histological investigations of porcine muscular tissue reveal drastically reduced boiled zones and zones of oedema formation at controlled cuts in comparison to common uncontrolled treatments. A further comparison of the harmful components in the electrosurgical smoke shows the great advantage of the new system.