Proteasome stress in skeletal muscle mounts a long-range protective response that delays retinal and brain aging

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Nitrosamine carcinogenicity: A quantitative relationship between molecular structure and organ selectivity for a series of acyclic N-nitroso compounds

A mathematical model has been developed which describes the selectivity between liver and other target organs for a series of carcinogenic N-nitrosodialkylamines. The relationship requires structural terms for the parent molecule as well as for the potential metabolites. This suggests that the nitrosamine metabolites are involved in tumor induction and that they participate directly in the mechanisms responsible for selecting the target organ.     

Negative relationships in the family-of-origin predict attenuated cortisol in emerging adults

Negative childhood family environments have been associated with stress-related physical and psychological health consequences across the lifespan. The present study examined the relation between adverse relationships in the family of origin and physiological stress response, as measured by salivary cortisol, in emerging adulthood. Seventy-six university students (age range = 18-22) selected from intact married families-of-origin characterized by either negative (n = 39) or positive (n = 37) relationship quality engaged in a challenging role play task. Results from multilevel models indicated that those from negative families exhibited significantly lower salivary cortisol across the task than those from positive families. This relation did not change in strength or direction after controlling for experiences with abuse or recent anxiety or depressive symptoms. These findings suggest the significance of early family relationships on the long-term activity of the HPA axis.     

Response of pig lung to irradiation with accelerated 12C-ions

The response of pig lungs to irradiation with 12C-ions was assessed in two experiments to validate the procedures for heavy ion therapy planning at the Gesellschaft für Schwerionenforschung (GSI) and to explore their range of applicability. In both experiments, the target volume (spread-out Bragg peak, SOBP) was planned to be a 4 cm long cylinder with a diameter of 4 cm. Doses in the SOBP were prescribed to be equivalent to 5x4 Gy, 5x5.5 Gy and 5x7 Gy of x-rays in the first experiment, and to 5 fractions of 7 Gy and 9 Gy in the second experiment. The lung response in the first experiment was less than expected on the basis of earlier experiments with photons. Pneumonitis reaction and chronic fibrotic changes were observed outside the prescribed high-dose region. In the second experiment, the effects were more pronounced than had been expected on the basis of the first experiment. Changes were most intense in the high-dose region, but were also seen throughout the lung along the beam channel. Moreover, significant skin reactions were observed at the beam entrance site in all animals and - less pronounced - at the beam exit site in 3 of the 6 animals. In conclusion, the complex irradiation geometry of the pig lung, the changes of body weight between the two experiments, and insufficient accounting for a change in the relative biological effectiveness (RBE) computation led to substantial deviations of the observed reactions from expectations, the reasons for which could be identified in a subsequent analysis. The less pronounced lung reaction in the first experiment was due to an overestimation of RBE in a preliminary version of the algorithm for its determination. The extension of the fibrotic reaction resulted from the smear-out of the high-dose region due to density variations in tissue structures, respiratory movement, and limited positioning accuracy. The skin reactions at the entrance port reflect the different treatment geometry in the two experiments. The one unexplained observation is the mild skin reaction that was observed in the second experiment at the beam exit site.     

PRESENCE AND DISTRIBUTION OF BROMINE IN THYSANOCLADIA DENSA (SOLIERIACEAE,GIGARTINALES), A MARINE RED ALGA FROM THE GREAT BARRIER REEF1

Electron-probe X-ray microanalysis of freeze dried sections of growing branch tips of Thysanocladia densa Sander shows high concentrations of bromine in the region of the medulla. Indirect evidence infers that the Br is associated with intercellular, granular deposits which accumulate within the mucilage of the medulla. The concentration of Br decreases in older regions of the thalli.     

Model studies of nonsteady flow using magnetic resonance imaging

A bolus-tracking magnetic resonance imaging (MRI) method has been employed to measure velocity profiles for oscillatory flow with and without a steady flow component as well as pulsatile flow in an axisymmetric tube model. A range of flow conditions within normal physiological limits was tested. The imaged velocity profiles were observed to be generally in accord with theoretical predictions. Instantaneous flow rates calculated from the MR images agreed well with those assessed using an ultrasonic flowmeter. Because MRI is noninvasive and poses few risks to subjects, this technique is potentially useful for studying vascular hemodynamics in vivo.     

Biological verification of heavy ion treatment planning

Chinese hamster ovary (CHO) cells and thermoluminescent detectors (TLD-700) were used for physical and biological verification of heavy ion treatment planning. Experiments were performed in a cylindrical water phantom, in some cases with lung and bone equivalent material in front of the target volume. The results confirm the possibility of using thermoluminescent detectors for a quantitative verification of dose distributions. CHO cells can be used at least for qualitative dose verification. Received: 15 December 1997 / Accepted in revised form: 6 February 1998     

Calculations of heavy-ion track structure

A Monte Carlo model is presented to study details of the energy deposition inside tracks of heavy charged particles in water vapor. The input data for most of the calculations based on the binary encounter approximation are double-differential cross sections for electron emission after heavy-ion impact. The paths of the liberated electrons are simulated, taking into account elastic scattering, ionization, and excitation. Each basic interaction of an electron or heavy ion is treated individually. Radial dose distributions and specific energy deposition are calculated for projectiles from protons to uranium in the energy range from one to several hundred megaelectron volts per unified atomic mass unit. Good agreement with measurements in tissue-equivalent gas and propane is obtained for light and medium-heavy projectiles, whereas for heavy projectiles such as uranium, deviations around a factor of 2–3 are observed.