[en] These studies show RBE/sub ave/ as a function of depth in water. The maximum RBE is obtained near the Bragg curve and has a value of 1.66. The results can be used to predict the relative biological effectiveness in arbitrary beams, when the absolute particle fluences can be calculated, and to interpret the results of radiobiological experiments performed at any value of the water thickness along the Bragg curve of 670-MeV/A neon ions used in the last several years of research at the Lawrence Berkeley Laboratory Bevalac Biomedical Facility. The results should also be directly applicable to treatment planning in clinical applications of high energy heavy-ion beams. 1 ref., 3 figs

[en] It appears from this group of three patients that regional cerebral brain blood flow is closely coupled to regional metabolic rate in Alzheimer's disease. If this is the case with a larger series of patients, the rCBF measurement could be used to supplant the more expensive and time consuming ¹⁸FDG studies. The method should also have utility in measurement of flow-metabolism coupling in great variety of other brain disorders, or of flow alone, the latter especially in studies on normal subjects in which brain function is manipulated experimentally to measure flow changes during normal brain function. 1 fig., 1 tab

[en] The wobbler system has now been used for one year in treating over 25 patients. In the last five months of full-time operation 18 patients have been treated for a total of 255 treatments. Its reliability and consistency have been comparable to that of the double-scattering system previously used for patient treatment. Neon ions of an energy per nucleon of 456 and 585 MeV, corresponding to clinically usable ranges at treatment isocenters of 18.6 and 27.6 cm of water equivalent thicknesses, respectively, have been developed. 3 refs

[en] We have investigated the number and distribution of radiolesions produced by x rays and accelerated atomic nuclei in mammalian cells. This is a difficult task because the initial lesions in DNA are usually of atomic dimensions. During most of the cell division cycle, we cannot observe DNA in the cell nucleus without killing the cells and highly denaturing the genetic material. Premature chromosome condensation make chromatin lesions visible. By use of these lesions are produced in a random Poisson distribution after doses of x rays, but exposures to accelerated heavy ions result in distributions of lesions that were very different from Poisson. 4 refs., 4 figs

[en] These results show the 3-mm BGO crystals can improve the resolution in positron tomography by a substantial factor. This measured crystal-pair resolution of 2.4 mm FWHM and the reconstructed image resolution of 2.9 mm FWHM at the center of the tomograph are in good agreement with expected values. The most serious limitation of the detector design is that only a single section can be imaged. 4 refs., 4 figs

[en] This study showed that repair of potentially lethal damage from neon ions was less than that measured after comparable x-ray doses, but there was no difference in the magnitude of potentially lethal damage repair with or without iododeoxyuridine (IUDR). These results suggest that IUDR sensitizes primarily by increasing the amount of alpha-type damage (''single hit killing'') and agrees with the current hypothesis that sensitization results from the cation of localized regions of heavy DNA damage. These results also suggest that IUDR is likely to function effectively as a sensitizer in fractional radiotherapy regimens utilizing either photons or clinically useful heavy-ion beams, particularly where a tumor might exist in a substrate of normal tissues which would have slower turnover than the tumor. 2 figs

[en] During the past year three new elements have been introduced into the beam line at the Bevatron to improve patient treatment. These are the wobbler magnets, the bar-ridged filters, and the binary absorber. The wobbler consists of a pair of orthogonal dipole magnets that sweep the beam in concentric circles up to 30 cm in diameter. This device replaces the lead scattering-foil system for spreading the beam laterally. This change allows the reduction of the beam energy from 670 MeV/amu to 585 MeV/amu while maintaining the same depth of penetration in the patient. The binary absorber is a set of copper and aluminium plates of binary increments in thickness. Like the variable thickness water column, which it replaces, the binary range absorber sets the residual range of the particles as they enter the final patient compensating filtering. 6 refs., 3 figs., 1 tab

[en] In order to distinguish enhanced repair of a sequence due to its transcriptional activity from enhanced repair due to chromatin alterations brought about by integration of a sequence into the genome, we have investigated the repair of damage both in endogenous genes and in cell lines that contain an integrated gene with an inducible promoter. The endogenous genes we are studying are the metallothioneins (MTs), a multigene family in man consisting of about 10-12 members. Cultured cells were exposed to 10-J/m² uv light and allowed to repair in the presence of bromodeoxyuridine. The DNA was then isolated, digested with Eco RI, and fully hybrid density DNA made by semiconservative synthesis was separated from unreplicated DNA by centrifugation in CsCl density gradients. Unreplicated, parental-density DNA was then reacted with a monoclonal antibody against bromouracil. 1 ref., 1 fig., 1 tab

[en] We have previously reported measurements of clonogenic cell survival in R-1 rat rhabdomyosarcoma tumors of the R2C5 subline following in situ irridation with 225-kVp x rays or with 557-MeV/u neon ions in the distal position of a 4-cm extended-peak ionization region. X ray and neon ion were shown to reduced the initial surviving fraction to 0.025. Significant 5-fold and 10-fold decreases in the fraction of clonogenic cells were observed between 3 and 4 days after irradiation with peak neon ions and x rays, respectively. These results represent the first time that a delayed decrease of this magnitude in postirradiation cell survival has been observed for a rat rhabdomyosarcoma tumor line. Several factors related to tumor-host interactions and the tumor cell environment following large doses of radiation are considered in an attempt to explain significant decrease in clonogenic cell survival. 4 figs

[en] Transfers of lipids and proteins between different lipoproteins are known to occur in the course of their metabolism. It is likely that these transfers take place during transient physical associations between lipoprotein particles, but the nature and chemical basis for such interactions are poorly understood. The fact that lipid and apolipoprotein movements are particularly prevalent during the intravascular lipolysis of triglyceride-rich lipoproteins suggested to us that lipolysis products accumulating on these particles might promote physical binding with other lipoproteins. To test this hypothesis, we studied interactions between very low-density, low density, and high-density lipoproteins in the setting of partial lipolysis by bovine milk lipoprotein lipase in the presence of limited unesterified fatty acid acceptor. 2 figs., 1 tab