Gallium-67 localization in rat and mouse tumors.

Various nonosseous tumors in mice and rats concentrate gallium-67-ESR-586 preputial gland carcinoma, P-1798 lymphosarcoma, C3H/ HeJ mammary tumor, AKR/J thymic lymphoma, R-3259 giant cell sarcoma, Walker-256 carcinosarcoma, and a new transplantable neoplasm of rats. This last tumor showed the greatest affinity for galliun. Viable tumor cells are mainly responsible for uptake of gallium-67; autoradiographic studies indicate it is chiefly located in tumor cytoplasm.

Isolation and partial characterization of a 67Ga-binding glycoprotein from Morris 5123C rat hepatoma.

A Glycoprotein, particularly high in tumors, has been extracted from Morris 5123C rat hepatomas and purified. The compound constitutes a major binding component for 67Ga in this hepatoma. It has a molecular weight of approximately 45,000. Its molecular weight was determined by sodium dodecyl sulfate:polyacrylamide gel electrophoresis and by Sephadex G-200 superfine gel filtration. The steps involved in its extraction and purification include ultrafiltration, gel filtration through Sephadex G-200 superfine, ion-exchange chromatography on diethylaminoethyl Sephadex A-50, and hydroxylapatite chromatography. The homogeneity of the compound was established by gel electrophoresis. The NH2-terminal residue, the percentage of nitrogen, the nonamino carbohydrate content, and the amino acid composition are reported.

A quantitative study of the subcellular localization of 67Ga.

This paper describes a quantitative procedure for the isolation of 67 Ga-binding granules (GBG) from normal rat liver and Morris 5123C hepatoma homogenates by a combination of rate and isopyknic density gradient zonal centrifugation. Another class of GBG has been found that is much smaller than the lysosomal GBG we have previously described. These smaller particles, or microvesicles, bind the largest portion of the 67Ga found in the hepatoma whereas, in the liver, the GBG lysosomes are the major binding component. Previously, we had shown that considerably more 67Ga is taken up in hepatoma than in liver (as percentage of administered dose per g of tissue). The preferential association of 67Ga with these microvesicles in the 5123C hepatoma may be indicative of a basic difference between normal and malignant tissue.

Studies of the vivo uptake of Ga-67 by an experimental abscess: concise communication.

The blocking of Ga -67 plasma protein-binding sites-by administration of scandium citrate, ferric citrate, and a colloidal hydrous ferric oxide preparation-reduced the uptake of Ga-67 in normal soft tissues and also that in the viable portion of an experimental abscess. On the other hand, enhancement of Ga-67 plasma protein binding by administration of rabbit apotransferrin increased Ga-67 uptake in both abscess and normal soft tissues. These results indicate that the pathways of Ga-67 from blood into inflammatory processes and normal soft tissues may be similar. However, when Ga-67 plasma protein binding was increased by inducing anemia, a markedly decreased Ga-67 uptake in the abscess resulted, whereas uptake in normal soft tissue was still elevated. It is possible that the discrepancy between the effects of apotransferrin and anemia on abscess-tissue uptake of Ga-67 resulted from a secondary effect produced by anemia, i.e., a decrease in the macrophage population in the abscess. Taken as a whole, the results obtained suggest that Ga-67 leaves the blood and enters inflammatory lesions by pathways that are probably quite different from those in a soft-tissue tumor, and that the routes for abscesses may be similar to those occurring in normal soft tissues.

The effect of scandium on the tissue distribution of Ga-67 in normal and tumor-bearing rodents.

In rats and mice the intravenous administration of scandium before or with Ga-67 produces an increase in Ga-67 excretion and bone deposition, coupled with pronounced decreases in the uptake of Ga-67 in soft tissues. These effects result from the blocking by scandium of Ga-67 plasma-protein binding sites, which forces Ga-67 into an unbound or loosely bound state. This increases Ga-67 excretion and bone deposition, which in turn acts to produce greatly reduced Ga-67 uptake in soft tissues. When tumor-bearing rats and mice are administered scandium, similar effects occur, but the uptake of Ga-67 by tumor tissue remains unchanged. This suggests that Ga-67 enters tumor and normal soft tissues by different routes. With tumor, an unbound or loosely bound form of gallium is primarily involved, whereas with normal soft tissues this route is apparently of minor importance.

Studies of the in vivo entry of Ga-67 into normal and malignant tissue.

Previous studies of the effect of scandium on the tissue distribution of Ga-67 suggest that Ga-67 makes its initial in vivo entry into normal and malignant tissues by different routes. (Scandium blocking of plasma protein Ga-67 binding increased Ga-67 excretion, decreased its uptake in normal tissues, but had little effect on rodent tumors.) In further studies we have used other methods to alter the plasma binding of Ga-67. Iron saturation of plasma produced effects on Ga-67 tissue distribution similar to those observed with scandium. On the other hand, increasing Ga-67 plasma binding through induction of anemia and administration of apotransferrin produced the reverse of the effects observed with scandium and iron. We conclude that the initial in vivo entry of Ga-67 into tumor tissue involves mainly an unbound or loosely bound form of Ga-67, whereas its uptake by normal soft tissues is strongly promoted by its binding to transferrin.

Analysis of rabbit tear fluid using capillary electrophoresis with UV or laser-induced fluorescence detection.

In preliminary studies of the development of tear analysis methodology that may eventually be useful in the clinical setting, the authors evaluated various protocols for analyzing rabbit tears by capillary zone electrophoresis (CZE). Conditions included the use of a 50-mM monosodium phosphate buffer, pH 2.5, or a 400-mM sodium borate buffer, pH 8.9, both with ultraviolet (UV) detection, as well as a 50-mM borate buffer, pH 8.5, with laser-induced fluorescence (LIF) detection of ATTO-TAG CBQ (Molecular Probes, Inc., Eugene, OR, U.S.A.) derivatized tears. All CZE analyses were performed with a P/ACE System 2100 instrument equipped with System Gold software (Beckman Instruments, Fullerton, CA, U.S.A.), using a 50 microns x 57 cm (50 cm to the window) fused-silica capillary, at 25 degrees C, with constant voltage of 20 kV for UV detection and 11 kV for LIF detection. Tear samples were collected from normal rabbit eyes by means of 10-microL glass micropipets. The volume of each sample was approximately 2 microL. Analysis using the phosphate buffer with UV detection produced as many as 35 peaks in each sample, of which 11 peaks were readily discerned. This compared favorably with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, which produced 32 bands with silver staining and 11 quantifiable bands with Coomassie brilliant blue staining. Many of the tear protein components have yet to be identified. CZE analysis with the high-ionic-strength borate buffer with UV detection produced only four peaks, and the low-ionic-strength borate buffer with LIF detection produced only six peaks. CZE analysis was completed in less than 1 hr, compared with 7-8 hr for SDS-PAGE. In summary, CZE analysis of tear fluid is comparable to CZE analysis of other bodily fluids and shows great potential for use in clinical diagnosis as well as for enhancing our understanding of the cellular actions of tears on the front of the eye.

A new method for labeling microspheres with 68Ga.

We have developed a simple, highly efficient, and rapid technique for labeling a commercially available human serum albumin microsphere preparation with 68Ga for use in positron tomography. An isotonic acetate buffer system is use. Maximum 68Ga labeling is obtained at pH 4.8 (approximately 97%) but deviations from that pH (e.g., 0.5 of a pH unit) produce only minor decreases in binding efficiency. The preparation is stable on standing over a period of 4 h, and in vivo studies in the rat and dog show it to be specific for the lungs. Little change occurs in the tissue distribution of 68Ga over a period of approximately 1 h.

Percutaneous injuries during oral and maxillofacial surgery procedures.

PURPOSE: This study estimated the frequency of percutaneous injuries (Pls) to dental health-care workers during oral and maxillofacial surgery and examined the circumstances surrounding the incidents. MATERIAL AND METHODS: A self-reported, prospective study was conducted to document Pls incurred during oral and maxillofacial surgery performed on outpatients and inpatients over 1-month and 6-month periods, respectively. Among the study variables examined were the numbers of patients treated, number and types of procedures performed, duration of treatment, numbers and types of health care workers at risk, treatment setting, and number of injuries. RESULTS: Four injuries were recorded during 362 operating room procedures on 236 inpatients, for a rate of 1.1 Pls per 100 procedures (95% confidence interval: 0.3 to 2.8) and 1.7 Pls per 100 patients (95% confidence interval: 0.5 to 4.6). These four injuries occurred during 1,665 person-procedures (mean number of workers present at each procedure times the total number of procedures) for a rate of 0.24 Pls per 100 person-procedures (95% confidence interval: 0.1 to 1.0). Three injuries took place during fracture reductions; two were caused by surgical wire and the third by a needlepoint Bovie tip. One injury occurred during orthognathic surgery and involved a Woodson elevator. Residents recorded no injuries while treating 521 outpatients (0 Pls per 100 patients; 95% confidence interval: 0 to 0.6). CONCLUSION: The results support previous findings that Pls rarely occur during outpatients oral and maxillofacial surgery procedures. However, the findings suggest that operating room procedures for oral and maxillofacial surgery that use wire or involve fracture reduction may be associated with an increased risk of injury. Strategies such as using a cork or sponge to cap sharp wires or instruments, and protecting hands and fingers by double gloving, may be used to decrease the risk of Pl.

Gallium-67 distribution in pregnant mammals.

Studies on the distribution of 67Ga in pregnant rabbits showed a marked concentration of the isotope in uterine tissue and flushings of 5-day pregnant rabbits 24 hours after isotope injection. The isotope no longer localized throughout the uterine tissues and flushings on injection of 7- to 8-day pregnant rabbits but was specifically associated with the blastocysts and sites of implantation. As the gestation time progressed 67Ga increasingly concentrated in placental and mammary tissue while the concentration in serum and thymus tissue decreased. The marked concentration in placental tissue was readily discernible on total-body scans of pregnant rabbits. Column chromatography of uterine washings and placental extracts from pregnant rabbits and thymus extracts from estrous rabbits showed most of the isotope associated with moieties greater than or equal to 200,000 MW whereas the isotope in "milk" and extracts of mammary tissue was bound to components of 25,000-35,000 MW. Extracts of thymus from pregnant rats showed a marked, selective loss of 67Ga binding in two peaks of approximately 50,000 and 120,000 MW compared to the chromatographic profile of extracts from normal rat thymus.

90Y-labeled monoclonal antibodies for cancer therapy.

Monoclonal antibody 17-1A, which has specificity for colorectal carcinoma, was labeled with 90Y (10-20% radiolabeling yield). Tissue distribution studies in tumor-bearing nude mice were carried out. 90Y-labeled 17-1A showed good uptake in the SW 948 colon carcinoma cell line. However, 90Y-labeled A5C3, a monoclonal antihepatitis virus antibody studied as a control, showed similar uptake in this tumor. Neither antibody was taken up well by a WM-9 melanoma. It is believed that the loss of specificity observed is due to the low specific activity of the 90Y-labeled monoclonal antibody preparations used. This hypothesis is supported by radioimmunoassay data.

Molecular and cellular characterization of the 29-kilodalton peripheral membrane protein of Entamoeba histolytica: differentiation between pathogenic and nonpathogenic isolates.

To further characterize the 29-kDa surface antigen of Entamoeba histolytica, we analyzed the complete nucleotide sequence and compared the immunoreactivity of this antigen in pathogenic and nonpathogenic strains. Five cDNA clones (one 1.0-kb full-length clone, designated p13, and four partial-length clones) encoding the antigen were analyzed for allelic variation. Comparison of the nucleotide sequences revealed several single-nucleotide substitutions in all five cDNAs, two of which resulted in amino acid differences. Localization of the antigen to the amebic surface in a previous report (B. E. Torian, B. M. Flores, V. L. Stroeher, F. S. Hagen, and W. E. Stamm, Proc. Natl. Acad. Sci. USA 87:6358-6362, 1990) was corroborated by transmission electron microscopy showing colloidal gold particles on the surface of the trophozoites. Computer analysis of the deduced amino acid sequence predicted that the protein encoded by p13 was a hydrophilic peripheral membrane protein, and these data were confirmed by a Triton X-114 membrane extraction showing the presence of the 29-kDa antigen primarily in the aqueous phase of the detergent partition. Monoclonal antibodies to a fusion peptide differentiated between pathogenic and nonpathogenic clinical strains of E. histolytica in immunoblots. Although no immunoreactive epitopes were detected on nonpathogenic strains, Northern (RNA) analysis and DNA-DNA hybridization with a 700-bp cDNA probe demonstrated that mRNA and the gene encoding the 29-kDa surface antigen were present in both pathogenic and nonpathogenic clinical isolates.