Assessment of biological changes of continuous whole body exposure to static magnetic field and extremely low frequency electromagnetic fields in mice.

The question whether static magnetic fields (SMFs) and extremely low frequency electromagnetic fields (ELF-EMF) cause biological effects is of special interest. We investigated the effects of continuous whole body exposure to both fields for 30 days on some liver and blood parameters in mice. Two exposure systems were designed; the first produced a gradient SMF while the second generated uniform 50 Hz ELF-EMF. The results showed a gradual body weight loss when mice were exposed to either field. This is coupled with a significant decrease (P<0.05) in the levels of glucose, total protein and the activity of alkaline phosphatase in serum. A significant increase in lactate dehydrogenase activity was demonstrated in serum and liver paralleled with a significant elevation in hepatic γ-glutamyl transferase activity. The glutathione-S-transferase activity and lipid peroxidation level in the liver were significantly increased while a significant decrease in hepatic gluthathione content was recorded. A significant decrease in the counts of monocytes, platelets, peripheral lymphocytes as well as splenic total, T and B lymphocytes levels was observed for SMF and ELF-EMF exposed groups. The granulocytes percentage was significantly increased. The results indicate that there is a relation between the exposure to SMF or ELF-EMF and the oxidative stress through distressing redox balance leading to physiological disturbances.

Towards understanding the immune system.

It is proposed that using both self-non-self and danger theories give a better understanding of how the immune system works. It is proposed that comparing the immune system to the police force is useful in this case since the police respond both to danger or damage signals and foreign or suspicious behavior even if no danger signals existed. We also propose that due to low zone tolerance, immunotherapy needs to be combined with another treatment method for cancer, e.g., chemotherapy or/and radiotherapy, to get sufficient eradication of tumors. Finally, we propose that fractional order differential equations are more suitable than the familiar integer order differential equations. A fractional order example of two immune effectors attacking an antigen is given.

On modelling the immune system as a complex system.

We argued that immune system is an adaptive complex system. It is shown that it has emergent properties. Its network structure is of the small world network type. The network is of the threshold type, which helps in avoiding autoimmunity. It has the property that every antigen (e.g. virus or bacteria) is typically attacked by more than one effector. This stabilizes the equilibrium state. Modelling complex systems is discussed. Cellular automata (CA)-type models are successful, but there are much less analytic results about CA than about other less successful models e.g. partial differential equations (PDE). A compromise is proposed.

Evaluation of the accuracy and precision of lung aerosol deposition measurements from planar radionuclide imaging using simulation.

Planar images of known, theoretical distributions of radioaerosol in the lung have been simulated using lung models derived from magnetic resonance studies on human subjects. Total lung activity was evaluated from the simulated images together with the absolute penetration index (PI) and a relative value expressed as a fraction of that in a simulated ventilation image. The accuracy and precision of these measurements were calculated by comparison with the true values used in the simulation. Total activity was assessed with systematic errors within 5% and precision within 6.5%. Measured PIs varied only slowly with true PI and inter-model variation masked changes between measurements on the different distributions. The relative PI reduced inter-model variation and provided significant differences between all the distributions. PI was significantly affected by misalignment of the lung region of interest. The conducting airways deposition fraction (CADF) used in the simulation correlated linearly with the fractional activity in a central lung region, allowing CADF to be estimated with a precision of 21%.

Three-dimensional description of pulmonary deposition of inhaled aerosol using data from multimodality imaging.

UNLABELLED: Three-dimensional assessment of pulmonary deposition of inhaled aerosol may be performed using SPECT. The use of aligned anatomical images enables improved accuracy of quantification and anatomical localization of deposition. METHODS: Techniques of analyzing these data and their application to deposition studies of two nebulizer-generated aerosols (mass median diameter 1.5 and 6.5 microM respectively) in 12 normal subjects are described. The deposition data were transformed to a standard hemispherical shape and the mean distribution pattern for each aerosol evaluated. Deposition by airway generation was then calculated using a spatial model of airway morphology. The results were compared to those from planar image analysis. RESULTS: The hemispherical transform yielded considerably more qualitative information on deposition pattern. The central-to-peripheral concentration ratio between conducting and alveolated airways was 5.27 for the coarser aerosol and 2.43 for the fine. The two-dimensional spatial estimates of the ratio were 2.61 and 2.03 respectively. CONCLUSION: Analysis of multimodality imaging data considerably enhanced information on deposition compared to planar imaging. It provides new data on aerosol deposition which will be of value to physicians involved in drug inhalation therapy.

Assessment of deposition of inhaled aerosol in the respiratory tract of man using three-dimensional multimodality imaging and mathematical modeling.

Multimodality medical imaging enables measurement of the three-dimensional spatial distribution of a radiolabeled aerosol within the lung. Using a conceptual spatial morphological model these data may be transformed to provide information on deposition per airway generation. This methodology has been used to study the intrapulmonary deposition patterns of two formulations of a metered dose inhaler and two nebulizers in control subjects. The nebulizer study has also been stimulated using a computer model of deposition. The comparison between derived experimental results and those from computer modeling shows areas of agreement, although there are also areas of discrepancy. The new methodology has considerable potential value in the fields of inhalation therapy and deposition modeling, although more detailed validation is still required.

Modelling the effect of charge on selective deposition of particles in a diseased lung using aerosol boli.

The technique of using a charged bolus of aerosol to deliver a drug or other agent is advantageous since sites of interest within the lung can be selectively targeted. Ideally, the volume of the bolus should match that of the targeted region allowing the aerosol bolus particles to be confined to the selected area during the pause period after inhalation. Our existing computer model for predicting the deposition of charged aerosol particles has been developed to encompass aerosol boli, some diseased lung morphologies and drug dose administered per breathing cycle. Aerosol deposition in the targeted region is found to be enhanced by increasing particle charge, pause period and particle size. For particles in the size range 1-2.5 microm, aerosol deposition in the region affected by bronchoconstriction does not alter significantly with flow rate variation (range 250-1000 ml s(-1)) for a targeted charged bolus of matched volume. The technique may enable the optimal delivery of therapeutic or other agents to diseased or normal lungs.