Matrix bounds of the discrete ARE solution

This paper provides new lower and upper matrix bounds of the solution to the discrete algebraic Riccati equation. The lower bound always works if the solution exists. The upper bounds are presented in terms of the solution of the discrete Lyapunov equation and its upper matrix bound. The upper bounds are always calculated if the solution of the Lyapunov equation exists. A numerical example shows that the new bounds are tighter than previous results in many cases.     

Prothymosin alpha 1 effects in vitro on chemotaxis, cytotoxicity and oxidative response of neutrophils from melanoma, colorectal and breast tumor patients

Immunoregulatory effects of thymic peptides on functions of polymorphonuclear leukocytes (PMNs) are poorly investigated. We studied the effects of prothymosin alpha 1 (Pro alpha 1) on PMNs from patients with colorectal tumors, breast tumors and melanoma (total n = 37) in comparison with healthy donors (n = 18), with respect to chemotaxis, cytotoxicity against HCT-116 colon tumor cells, oxidative response (chemiluminescence reaction) as well as expression of surface marker molecules. We found that Pro alpha 1 was equally effective in stimulating the chemotactic activity of PMNs from tumor patients and healthy donors (43% increase). PMNs from tumor patients, especially with breast tumor, showed a significant enhancement of cytotoxicity against the tumor target cells in comparison with healthy donors. With respect to the PMNs cytotoxicity, only about 50% of the colorectal tumor patients and healthy donors responded to Pro alpha 1 and FMLP. As to the oxidative response of PMNs, elevated levels were found only among colorectal tumor patients. Pro alpha 1 significantly increased the oxidative response in breast and colorectal tumor patients by 55% and 25%, respectively. Pro alpha 1 decreased the expression of CD16 on PMNs of healthy donors, but not that of CD11a, CD11b, CD11c, CD13, CD14, CD15 and CD32. Therefore, we suggest, that Pro alpha 1 may improve some PMN functions of tumor patients, associated with the proposed role in host-tumor interaction.     

Artefacts in MR images of electrical current distribution

Artefacts in images of electrical current distribution measured by magnetic resonance imaging (MRI) are presented. These artefacts, caused by the effects of the connecting cables used to apply the electrical current to the object during the MRI scan, can lead to an underestimation of the magnitude of the electrical current measured in the experiment. The size of this underestimate depends upon the experimental geometry, but in the experiments and simulations described here, performed with a cylindrical phantom approximately 8 cm long and 8 cm in diameter, the difference can be 27%. These artefacts are reduced if the connecting cables are rigidly fixed to the object so that the induced magnetic field is correctly measured during the MRI experiment.     

Breast-feeding exposure of infants to cadmium, lead, and mercury: a public health viewpoint

The purpose of this report is to provide an overview of the public health implications of exposure via breast milk to cadmium, lead, and mercury for nursing infants and to provide health-based guidance. Daily intakes were calculated and compared with guidance values used for public health assessments at hazardous waste sites. Cadmium, lead, and mercury under normal conditions are found in breast milk at concentration ranges of < 1 microgram/L, 2-5 micrograms/L, and 1.4-1.7 micrograms/L, respectively. Women exposed environmentally or occupationally can have higher levels in their breast milk. Concentrations of about 5 micrograms/L (cadmium), 20 micrograms/L (lead), and 3.5 micrograms/L (mercury) appear to be adequate screening levels. Many factors affect both the distribution of cadmium, lead, and mercury in breast milk and the health consequences to an infant. It is not clear what additional impact low-level exposure via breast milk may have on an infant born with a body burden to one of these metals. There is sufficient evidence to make the case that contaminated breast milk is a source of potential risk to infants in certain populations. Prevention strategies that include behavior modification and proper nutrition should be communicated to women at risk. Identification and elimination of exposure pathways and a critical analysis of the benefits of breast feeding versus heavy metal exposure are needed on a site-specific or individual basis. Research is required to better understand the impact of low-level exposure to heavy metals via breast milk. Breastfeeding should be encouraged under most circumstances.