Floating rates of synchronized CHO fibroblasts following 60Co gamma irradiation]

Monolayer cell colonies normally are pushing off single cells, which go into suspension. A dose-dependent increase of these cell detachments followed by readhesion and colony forming would influence the colony survival curve. Detached cells being in suspension can be verified by means of the colony forming test after decantation and inoculation of the medium. The amount of colony forming cells in the late phase of synthesis does scarcely change following 300 rds of 60Co gamma irradiation. The diminution of cell adhesion expected as a result of radiation damage could not be observed.     

Functional changes in the pig kidney following irradiation with fractionated doses of fast neutrons (42 MeVd-->Be).

The right kidney of female Large White pigs, approximately 14 weeks old, was irradiated with fractionated doses of fast neutrons (42 MeVd-->Be). The total doses used were 6.6-9.2 Gy. Changes in kidney function, assessed as the functional index (FI, where FI = irradiated kidney function/unirradiated kidney function) or as individual kidney glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), were serially determined up to 104 weeks after irradiation using 99Tcm-DTPA and 131I-hippuran renography. The animals were then euthanized, the kidneys removed and weighed. A dose-dependent reduction in FI was seen within 13 weeks of irradiation. Measuring individual kidney function revealed a hyperaemic response in both irradiated and unirradiated kidney 4 weeks after irradiation. This was followed by a dose-dependent reduction in irradiated kidney GFR and particularly ERPF. The ED50 value for the impairment in ERPF, assessed as the percentage of irradiated kidneys exhibiting a > or = 50% reduction in ERPF, was significantly lower than that for GFR, i.e. 7.20 +/- 0.10 Gy compared with 8.44 +/- 0.07 Gy (p < 0.001). A dose-related reduction in irradiated kidney weight was also observed. These fast neutron-induced changes in renal function and weight are qualitatively similar to those observed following photon irradiation of the pig kidney.     

Radionuclide evaluation of left ventricular function with nonimaging probes

Portable nonimaging probes have been developed that can evaluate left ventricular function using radionuclide techniques. Two modes of data acquisition are possible with these probe systems, first-pass and gated. Precordial radiocardiograms obtained after a bolus injection can be used to determine cardiac output, pulmonary transit time, pulmonary blood volume, left ventricle ejection fraction, and left-to-right shunts. Gated techniques can be used to determine left ventricular ejection fraction and sytolic time intervals. Probe-determined indices of left ventricular function agree excellently with comparable measurements determined by conventional camera-computer methods as well as by invasive techniques. These have begun to be used in a preliminary manner in a variety of clinical problems associated with left ventricular dysfunction. This review discusses the types of probe systems available, the methods used in positioning them, and details the specifics of their data acquisition and processing capacity. The major criticisms of probe methods are that they are nonimaging and that they measure global rather than regional left ventricular function. In spite of these criticisms, probe systems, because of their portability, high sensitivity, and relatively low cost are useful supplements to conventional camera-computer systems for the measurement of parameters of left ventricular performance using radionuclide techniques.     

Excitation of 83mKr by 60Co irradiation

The 1.83 h half-life isomeric activity of ^83mKr induced by 7.4 PBq (200 kCi) ⁶⁰Co irradiation has been measured by a 4π proportional counter within a large background of ⁸⁵Kr decay. The main activation level has been identified at 1170 keV. The cross section for the ⁸³Kr(γ,γ′)^83mKr reaction integrated over this level has been determined relative to a known value for ^115mIn production and found to be (3.2±0.7)10⁻²⁶ cm² eV, in good agreement with the value calculated from the level scheme.