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Biomedical subjects

L Breger

Publications and source records attributed to L Breger.

16 recordsLinked to original sources
PubMed1998

Three-dimensional structure at the base of the mantle beneath the central pacific

Forward modeling of differential travel times of phases sensitive to lowermost mantle beneath the central Pacific reveals lateral heterogeneity that is higher in amplitude than predicted by tomographic models. A broad zone of low S velocity (-4 percent with respect to standard models), which may correspond to the base of a thermal "plume," narrows and is deflected as it extends to about 1000 kilometers above the core-mantle boundary. To the east of this zone, a localized region of fast S velocity (+5 percent) suggests strong heterogeneity or anisotropy related to the presence of high pressure and temperature assemblages, which may or may not involve core material. Its presence could also explain the observation of precursors to core reflected phases in this region.

Journal Article↗
PubMed1997

Effects of low-intensity AC and/or DC electromagnetic fields on cell attachment and induction of apoptosis.

Rat tendon fibroblast (RTF) and rat bone marrow (RBM) osteoprogenitor cells were cultured and exposed to AC and/or DC magnetic fields in a triaxial Helmholtz coil in an incubator for up to 13 days. The AC fields were at 60 and 1000 Hz and up to 0.25 mT peak to peak, and the DC fields were up to 0.25 mT. At various combinations of field strengths and frequencies, AC and/or DC fields resulted in extensive detachment of preattached cells and prevented the normal attachment of cells not previously attached to substrates. In addition, the fields resulted in altered cell morphologies. When RTF and RBM cells were removed from the fields after several days of exposure, they partially reattached and assumed more normal morphologies. An additional set of experiments described in the Appendix corroborates these findings and also shows that low-frequency EMF also initiates apoptosis, i.e., programmed cell death, at the onset of cell detachment. Taken together, these results suggest that the electromagnetic fields result in significant alterations in cell metabolism and cytoskeleton structure. Further work is required to determine the relative effect of the electric and magnetic fields on these phenomena. The research has implications for understanding the role of fields in affecting bone healing in fracture nonunions, in cell detachment in cancer metastasis, and in the effect of EMF on organisms generally.

Animals↗
PubMed1977

A one-year follow-up of two forms of brief psychotherapy.

How do patients who had brief behavior therapy evaluate change in themselves as compared to those who had brief psychoanalytically oriented psychotherapy a year following termination of their treatment? Restults of the follow-up study reveal that over-all, patients rated themselves at one-year follow-up as improved over their status at three months after therapy but less so than at the time of termination of therapy. The form of therapy did not make a difference in the patients' evaluation of change.

Attitude of Health Personnel↗