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Biomedical subjects

Jürgen Fuchs

Publications and source records attributed to Jürgen Fuchs.

7 recordsLinked to original sources
PubMed2006

Ultrasound-guided central venous cannulation: is there a difference between Doppler and B-mode ultrasound?

STUDY OBJECTIVE: To compare the success of Doppler and B-mode ultrasound-guided internal jugular vein (IJV) catheterization with respect to body mass index (BMI). STUDY DESIGN: Prospective, randomized study. SETTING: Section for cardiovascular anesthesia of a university hospital. PATIENTS: 338 consenting patients were analyzed. INTERVENTIONS: Subjects receiving central venous catheters for scheduled cardiac surgery were divided into two groups. After induction of general anesthesia, the right or left IJV was assessed for midcervical cannulation approach. In the Doppler group (n = 189), a SonoGuide2 with a 5.0-MHz probe was used. In the B-mode group (n = 149), the SiteRite II ultrasound system with a 7.5-MHz transducer was used. MEASUREMENTS AND MAIN RESULTS: There was a significant difference in the success rate of first needle pass between the two groups: Doppler group, 91% (172/189); B-mode group, 96.6% (144/149) (P = 0.045). A BMI of 30 and greater was associated with a significantly lower first needle pass success rate in the Doppler group (Doppler group, 77.1% [27/35]; B-mode group, 97.4% [38/39]; P = 0.011). The success rates in patients with a BMI below 30 for both methods were not different (Doppler group, 94.2% [145/154]; B-mode group, 96.4% [106/110]; P = 0.567). Arterial punctures occurred three times under Doppler guidance and twice under B-mode guidance. CONCLUSION: Cannulation of the IJV can be ensured and first needle pass success rate maximized by both ultrasound techniques. In patients with a BMI greater than 30, B-mode technique is superior to Doppler ultrasound.

Adolescent↗
PubMed2004

Kramers-wannier duality from conformal defects.

We demonstrate that the fusion algebra of conformal defects of a two-dimensional conformal field theory contains information about the internal symmetries of the theory and allows one to read off generalizations of Kramers-Wannier duality. We illustrate the general mechanism in the examples of the Ising model and the three-state Potts model.

Journal Article↗
PubMed2003

HPLC analysis of vitamin E isoforms in human epidermis: correlation with minimal erythema dose and free radical scavenging activity.

The content and composition of different vitamin E isoforms was analyzed in normal human skin. Interestingly the epidermis contained 1% alpha-tocotrienol, 3% gamma-tocotrienol, 87% alpha-tocopherol, and 9% gamma-tocopherol. Although the levels of tocotrienol in human epidermis appear to be considerably lower than reported in the hairless mouse, the presence of significant amounts of tocotrienol levels leads to speculation about the physiological function of tocotrienols in skin. Besides antioxidant activity and photoprotection, tocotrienols may have skin barrier and growth-modulating properties. A good correlation was found for epidermal alpha-tocopherol (r = 0.7909, p <.0003), gamma-tocopherol (r = 0.556, p <.025), and the total vitamin E content (r = 0.831, p <.0001) with the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging in epidermis, as assessed by electron paramagnetic resonance (EPR) spectroscopy. In human epidermis, alpha-tocopherol is quantitatively the most important vitamin E isoform present and comprises the bulk of first line free radical defense in the lipid compartment. Epidermal tocotrienol levels were not correlated with DPPH scavenging activity. The minimal erythema dose (MED), an individual measure for sun sensitivity and a crude indicator for skin cancer susceptibility, did not correlate with the epidermal content of the vitamin E isoforms. Hence it is concluded that vitamin E alone is not a determinant of individual photosensitivity in humans.

Chromans↗
PubMed2003

Occupational exposure to heavy metals: DNA damage induction and DNA repair inhibition prove co-exposures to cadmium, cobalt and lead as more dangerous than hitherto expected.

Co-exposure to cadmium, cobalt, lead and other heavy metals occurs in many occupational settings, such as pigment and batteries production, galvanization and recycling of electric tools. However, little is known about interactions between several heavy metals. In the present study we determined DNA single strand break (DNA-SSB) induction and repair capacity for 8-oxoguanine in mononuclear blood cells of 78 individuals co-exposed to cadmium (range of concentrations in air: 0.05-138.00 micro g/m(3)), cobalt (range: 0-10 micro g/m(3)) and lead (range: 0-125 micro g/m(3)). Exposure to heavy metals was determined in air, blood and urine. Non-parametric correlation analysis showed a correlation between cadmium concentrations in air with DNA-SSB (P = 0.001, R = 0.371). Surprisingly, cobalt air concentrations correlated even better (P < 0.001, R = 0.401), whereas lead did not correlate with DNA-SSB. Logistic regression analysis including 11 possible parameters of influence resulted in a model showing that cobalt in air, cadmium in air, cadmium in blood and lead in blood influence the level of DNA-SSB. The positive result with cobalt was surprising, since exposure levels were much lower compared with the TRK-value of 100 micro g/m(3). To examine, whether the positive result with cobalt is stable, we applied several logistic regression models with two blocks, where all factors except cobalt were considered preferentially. All strategies resulted in the model described above. Logistic regression analysis considering also all possible interactions between the relevant parameters of influence finally resulted in the following model: Odds ratio = 1.286(Co in air) x 1.040(Cd in air) x 3.111(Cd in blood) x 0.861(Pb in air) x 1.023(Co in air x Pb in air). This model correctly predicts an increased level of DNA-SSB in 91% of the subjects in our study. One conclusion from this model is the existence of more than multiplicative effects for co-exposures of cadmium, cobalt and lead. For instance increasing lead air concentrations from 1.6 to 50 micro g/m(3) in the presence of constant exposures to cobalt and cadmium (8 micro g/m(3) and 3.8 micro g/m(3)) leads to an almost 5-fold increase in the odds ratio, although lead alone does not increase DNA-SSB. The mechanism behind these interactions might be repair inhibition of oxidative DNA damage, since a decrease in repair capacity will increase susceptibility to reactive oxygen species generated by cadmium or cobalt. Indeed, repair of 8-oxoguanine decreased with increasing exposures and inversely correlated with the level of DNA-SSB (P = 0.001, R = -0.427). Protein expression patterns of individuals exposed to cobalt concentrations of approximately 10 micro g/m(3) were compared with those of unexposed individuals using two-dimensional gel electrophoresis. Qualitative and apparent quantitative alterations in protein expression were selective and certainly occurred in <0.1% of all proteins. In conclusion, the hazard due to cobalt exposure - that has been classified only as IIB by the IARC - seems to be underestimated, especially when individuals are co-exposed to cadmium or lead. Co-exposure may cause genotoxic effects, even if the concentrations of individual heavy metals do not exceed TRK-values.

Alcohol Drinking↗
PubMed2002

Kinetic measurements using EPR imaging with a modulated field gradient.

EPR imaging with modulated field gradient was applied for the investigation of fast diffusion processes. Three different imaging methods are possible: spectral-temporal, spatio-temporal, and spectral-spatial imaging. The time resolution is on the order of seconds and the spatial resolution is in the micrometer region. The efficiency of this imaging technique is demonstrated for the penetration of the spin probe Tempol in the skin of hairless mice biopsies. The skin is normally protected against the penetration of water soluble substances by the horny layer, a resistive thin lipophilic layer. Overcoming this horny layer for water soluble ingredients is one of the main practical problems for the topical application of pharmaceutics which could be investigated by EPR imaging. Different images represent the penetration behavior of the water soluble Tempol in the skin after treatment with the penetration enhancer DMSO (Dimethylsulfoxide) and after removing the horny layer.

Animals↗