The spatial distribution of platinum (Pt) in the kidney was studied by an autoradiographic technique, in which cisplatin (CDDP) was replaced by 195mPt-labeled CDDP, and by proton-induced X-ray emission (PIXE). Although both studies demonstrated comparable spatial distribution patterns, PIXE had the advantage that Pt concentrations could be determined quantitatively, in contrast to the relative information obtained by the autoradiographic technique. Using PIXE, the distribution of Pt in i.p. tumors was studied after i.p. administration of CDDP. The highest Pt concentrations were always found on the periphery of tumors, indicating that the periphery was exposed to a higher drug concentration than the center. Dose was correlated to the concentration of CDDP at both the center and the periphery (r = 0.99). The Pt concentration in the periphery was usually higher by a factor of 2-3 after i.p. administration than after i.v. treatment, whereas in the center of the tumor no concentration difference could be detected. The penetration depth of CDDP lay between 1 and 2 mm and was calculated from the differences in Pt concentration after i.p. and i.v. treatment. This indicates that the effective advantage of i.p. chemotherapy with CDDP in cases of cancers limited to the peritoneal cavity is accentuated at the periphery of the tumor.
A micro-PIGE (Proton-Induced 7-ray Emission) technique based on the delayed 5/2-' 1/2 nudear transition of fluotine (E'y = 197 keV, t#{189} 87 us) emitted after ' F(p,p y)' F reaction was used to detect and study the distribution of fluorine in the developing enamel organ during pre-eruptive stages, i.e., the transitional to early maturation stages of enamel formation in neonatal hamsters administered a single IP dose ofsodium fluoride (20 mg NaF/kg body weight). The aforementioned nudear reaction is unique for fluorine, and therefore detection of 'y-rays emanating from this reaction in a biological specimen implies a positive identifica. tion of fluorine at that particular site. Calcium and phosphorus X-rays were also recorded and used as parameters for assessment of the relationship between the degree of mmeralization and fluoride incorporation into the enamel or
The effect of dietary zinc deficiency on the mossy fiber zinc content of the rat hippocampus was investigated using PIXE (Particle Induced X-Ray Emission) spectroscopy. Using the proton microbeam (60 X 60 microns), 2 mm line-scans were made on hippocampal sections and the data were expressed as absolute zinc concentrations. Values of 55 and 136 ppm (dry weight) were found for the mean background zinc level and the maximum mossy fiber zinc level, respectively, in animals fed a control diet containing 50 ppm zinc. Treatment of these animals with dithizone caused about 50% reduction in the maximum mossy fiber zinc level. Feeding a zinc-deficient diet for 28 days did not cause a decrease in the mossy fiber zinc level, however, feeding the zinc-deficient diet for 90 days reduced the maximum mossy fiber zinc level by about 30%. The results are discussed in relation to the behavioral abnormalities that have been observed in zinc-deficient animals.
This paper contains a comparison between four experimental methods for the detection of trace metals in biological tissues, e.g. autoradiography, dithizone-, Timm-staining and microPIXE (Particle Induced X-ray Emission). As research object the hippocampus of the rat was chosen and mainly the Zn-distribution in the fascia dentata has been examined. The comparison was judged on four criteria: spatial resolution, specificity, quantification and influence of the protein binding of the metal on the outcome of each method. Some additional Timm and microPIXE experiments have been performed to compare the metal concentrations for both normal and Zn-deficient rats. The Zn/Cu ratio for both kinds of rats were calculated and some striking differences in the concentrations were obtained. The Zn/Cu ratio for a normal rat was found to be about 40% higher than for a deficient one.
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