The measurement of bioreductive capacity of tumor cells using methylene blue

PURPOSE: Methylene blue (MB) can be used as an intracellular electron acceptor. The purpose of this study was to demonstrate the usefulness of MB for the determination of total bioreductive capacity of cell suspensions. METHODS AND MATERIALS: We measured oxygen consumption by Clark electrode and pentose cycle activity by release of 14CO2 from 1-14C-glucose. RESULTS: Methylene blue catalyzes the reaction of intracellular reductants NADPH, NADH, and reduced glutathione (GSH) with oxygen, causing the production of hydrogen peroxide. The reaction rate correlates with the negative charge of molecule (NADPH(-4) > NADH(-2) > GSH(-1)), suggesting that reaction with positively charged oxidized MB is the limiting step of the reaction. In a cellular system MB causes the electron flow from cellular endogenous substrates to oxygen. It is activated by the disruption of the NADP+/NADPH ratio due to several processes. These are direct oxidation of NADPH and GSH, the GSH peroxidase catalyzed reaction of GSH with H2O2, followed by NADPH oxidation by oxidized glutathione (GSSG). This results in increased cellular oxygen consumption and stimulation of the oxidative limb of pentose cycle (PC) in the presence of MB. The cellular effect of MB differs from other electron accepting drugs. Diamide and tert-butylhydroperoxide act as direct oxidants, while MB is an electron carrier to oxygen. Accordingly, MB shows the highest effect on PC activation and oxygen consumption. CONCLUSIONS: Our results indicate that MB may be used for the determination of the total bioreductive capacity of the cells, measured by oxygen consumption and PC activation.     

Trends in the production and storage of fresh meat – the holistic approach to bacteriological meat quality

The aim of this review paper is to introduce readers to the modern approach to meat production as recommended by public authorities. No part of the food chain can be regarded alone but has to be seen as part of the whole. A holistic approach to fresh meat storage and retailing must therefore start with the living animal and cannot end with the sale of the meat. It must also include the consumers. One of the highest priority issues for consumers, producers and governments is food safety, and with it, consumer safety. Here we briefly describe the possibilities of keeping initial amounts of bacteria in meat low and modern storage of fresh meat. In future, the consumer must be incorporated in the meat food chain.     

A tight upper bound on the gain of linear and nonlinear predictorsfor stationary stochastic processes

One of the striking questions in prediction theory is this: is there a chance to predict future values of a given signal? Usually, we design a predictor for a special signal or problem and then measure the resulting prediction quality. If there is no a priori knowledge on the optimal predictor, the achieved prediction gain will depend strongly of the prediction model used. To cope with this lack of knowledge, a theorem on the maximum achievable prediction gain of stationary signals is presented. This theorem provides the foundation for estimating a quality goal for the predictor design, independent of a special predictor implementation (linear or nonlinear). As usual, the prediction gain is based on the mean square error (MSE) of the predicted signal. The achievable maximum of the prediction gain is calculated using an information theoretic quantity known as the mutual information. In order to obtain the gain, we use a nonparametric approach to estimate the maximum prediction gain based on the observation of one specific signal. We illustrate this by means of well-known example signals and show an application to load forecasting. An estimation algorithm for the prediction gain has been implemented and used in the experimental part of the paper     

Training family practice residents in abortion and other reproductive health care: a nationwide survey

The majority of residents responding to a 1995 survey of program directors and chief residents at 244 family medicine residency programs in the United States reported they had no clinical experience in cervical cap fitting, diaphragm fitting or IUD insertion and removal. For all family planning methods except oral contraceptives, no more than 24% of residents had experience with 10 or more patients. Although 29% of programs included first-trimester abortion training as either optional or routine, only 15% of chief residents had clinical experience providing first-trimester abortions. Five percent of residents stated they certainly or probably would provide abortions, while 65% of residents stated they certainly would not provide abortions. A majority (65%) of residents agreed that first-trimester abortion training should be optional within family practice residency programs. Residents were more likely to agree with inclusion of optional abortion training and with the appropriateness of providing abortions in family practice if their program offered the training.     

Sensorforschung in Österreich – Optische Sensorik

Ohne Zusammenfassung     

Thermo-hydro-chemical couplings considered in safety assessment of shallow tunnels subjected to fire load

Fire loading of concrete tunnel linings is characterized by various physical, chemical, and mechanical processes, resulting in spalling of near-surface concrete layers and degradation of strength and stiffness of the remaining tunnel lining. In this paper, the governing transport processes taking place in concrete at elevated temperatures are considered within a recently published fire-safety assessment tool [Savov K, Lackner R, Mang HA. Stability assessment of shallow tunnels subjected to fire load. Fire Safety J 2005; 40: 745–763] for underground structures. In contrast to consideration of heat transport only [Savov et al.], a coupled thermo-hydro-chemical analysis, simulating the heat and mass transport in concrete under fire loading, is performed, giving access to more realistic temperature distributions as well as gas-pressure distributions within the tunnel lining. These data serve as input for the structural safety assessment tool considering, in addition to the temperature dependence of mechanical properties, the effect of the gas pressure on the strength properties of the heated lining concrete. The combination of the two analysis tools (coupled analysis of governing transport processes and structural safety assessment) is illustrated by the fire-safety assessment of a cross-section of the Lainzer tunnel (Austria) characterized by low overburden (shallow tunnel).