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At least 937 records · Page 52Linked to original sources
PubMed1985

Iron(III)-nitrilotriacetate: an agent for reducing the time interval of tumor imaging with gallium citrate.

Increasing interest in the short-lived radionuclide 68Ga (t1/2: 68.2 min) has revived basic studies of gallium radiopharmaceuticals. Ga-citrate (Ga-cit), described as a polynuclear complex, possesses great affinity for tumor cells but is also bound by blood transferrin (Tf). Exploitation of reaction-rate differences in metal ion transference from Ga-cit to Tf (slow) and Fe-nitrilotriacetate (Fe-NTA) to Tf (fast) is put to use to attain a proper tumor/tissue ratio within practical time limits. Studies on administration mode, time and dose offered promising results for future 68Ga-cit tomographic studies.

Animals↗
PubMed1992

Suppression of experimental autoimmune encephalomyelitis by gallium nitrate.

We examined the effect of gallium (Ga) nitrate on the development of the development of experimental autoimmune encephalomyelitis (EAE). Weekly subcutaneous injections of 10-30 mg/kg prevented clinical signs as well as histopathological changes of EAE. The optimal timing of a single injection of Ga was 6 days after induction of EAE, with amelioration also apparent following a single injection on day 3 or 9 but not day 12. Ga administered in vivo suppressed myelin basic protein (MBP) and purified protein derivative-specific lymphocyte proliferative responses in vitro. Addition of Ga to MBP-specific T lymphocyte line cultures at various times after initiation of culture revealed that Ga exerts an effect at an early stage of cellular activation.

Animals↗
PubMed1991

Genotoxicity of beryllium, gallium and antimony in short-term assays.

The genotoxicity of beryllium, gallium and antimony compounds was studied with the rec, Salmonella mutagenicity and SCE assays. In the rec assay, all the salts of the metals, BeCl2, Be(NO3)2, GaCl3, Ga(NO3)3, SbCl3, SbCl5, and an oxide, Sb2O3, had DNA-damaging activity. None of the compounds was mutagenic to Salmonella. In the SCE assays using V79 cells, 2 antimony(III) compounds, SbCl3 and Sb2O3, and 2 beryllium compounds, BeCl2 and Be(NO3)2, induced SCEs significantly. Sb2O3, slightly soluble in water, was positive in both the rec assay and the SCE assay at very low doses.

Animals↗
PubMed1991

Interaction of aluminium and gallium with human lymphocytes: the role of transferrin.

Aluminium-transferrin (Al-Tf) and gallium-transferrin caused a dose-dependent decrease in proliferation of human peripheral blood lymphocytes cultured for 3 days with phytohaemagglutinin (PHA). Addition of apotransferrin reduced the inhibitory effect. Al added as AlCl3 or aluminium citrate had no effect, and there was no significant difference in the response of cells from renal failure patients with or without high serum Al levels or controls. Lymphocytes cultured in the presence of Al-Tf showed a dose-dependent uptake of Al, whereas uptake from aluminium citrate was low and not dose-dependent. Uptake from AlCl3 was very high but probably involved a nonspecific uptake mechanism. Levels of Al in freshly isolated lymphocytes were approximately 1.6 ng/10(6) cells, there being no difference between cells from patients and controls. It is concluded that Al, when bound to transferrin, may have a detrimental effect on lymphocyte function and might contribute to the decreased immune responsiveness of renal failure patients on haemodialysis. However, lymphocyte Al levels are probably not useful as a marker of Al overload in such patients.

Aluminum↗
PubMed1986

Detection of infection of a cardiac xenograft by gallium-67 scan.

We describe a case complicated by infection of a xenograft conduit with subsequent septic emboli to the left kidney in the setting of pulmonary atresia with ventricular septal defect which was positively imaged using radioactive gallium-67. Confirmation was provided by cross-sectional echocardiography and positive blood culture. The patient improved with antibiotic therapy.

Adolescent↗
PubMed1987

Metabolism and excretion of gallium arsenide and arsenic oxides by hamsters following intratracheal instillation.

The increasing use of gallium arsenide (GaAs) in the electronics industry has produced the need for pharmacokinetic and toxicologic data on GaAs. The disposition in male Syrian golden hamsters (n = 4) following intratracheal instillation of GaAs (mean volume diameter 5.8 micron), arsenic (III) oxide (arsenite), and arsenic (V) oxide (arsenate) at a dose of 5 mg/kg body weight was examined. Blood, kidney, liver, and lung samples were collected at 1, 2, and 4 days after administration. Excreta were collected daily. Urinary metabolite profiles were determined after separation on a mixed anion-cation-exchange column. Total As content was analyzed by direct hydride flame atomic absorption spectrophotometry after digestion. Arsenic blood levels after GaAs, arsenite, and arsenate administration were 0.185 +/- 0.041, 0.596 +/- 0.117, and 0.310 +/- 0.045 ppm, respectively, after Day 1. Arsenic blood levels after GaAs administration increased to 0.279 +/- 0.021 ppm on Day 2 indicating continued absorption while levels decreased for the arsenite and arsenate groups. At Day 1 the liver contained 0.565 +/- 0.036, 2.62 +/- 0.26, and 0.579 +/- 0.144% of the arsenic dose of GaAs, arsenite, and arsenate, respectively. The arsenite and arsenate were rapidly excreted in the urine with almost half the dose appearing after 4 days; in contrast, only about 5% of the GaAs was found at the corresponding time. Total recoveries, as arsenic equivalents, for the three compounds were between 75 and 80%. Ratios of the two major urinary metabolites (dimethylarsinic acid/total inorganic As species) were 1.41, 1.71, and 0.983 for GaAs, arsenite, and arsenate, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1989

Immunotoxicity of the semiconductor gallium arsenide in female B6C3F1 mice.

The effects of gallium arsenide (GaAs) exposure on immunocompetence of B6C3F1 female mice were investigated. GaAs was administered as a single intratracheal instillation at doses of 50, 100, and 200 mg/kg. Fourteen days after exposure, various cellular and humoral immune parameters were assessed. GaAs exposure increased spleen cellularity in a dose-dependent manner. However, the percentages of Thy 1.2 positive and Ig positive cells were decreased and that of F4/80 positive cells was increased dose dependently. The IgM and IgG antibody-forming cell response of the spleen to the T-dependent antigen sheep erythrocytes was reduced by 66 and 48%, respectively, at 200 mg/kg. Levels of the serum complement protein, C3, were increased by as much as 16% with no significant change in CH50 levels. The mitogenic response of splenic T cells to Con A and PHA was unaffected by GaAs, but that of B cells to LPS was increased by 52%. The delayed hypersensitivity response to keyhole limpet hemocyanin and mixed lymphocyte response were significantly reduced in a dose-dependent manner by GaAs exposure. Natural killer cell activity against the YAC-1 mouse lymphoma was enhanced in treated mice. Analysis of peritoneal exudate cells (PEC) revealed a dose-dependent decrease in number and a shift in the composition of PECs. The percentage of PEC monocytes increased from 53% of the population to 81%, while the lymphocytes decreased from 46 to 20%. The adherent PEC population demonstrated decreased phagocytosis of covaspheres and increased phagocytosis of chicken erythrocytes (CRBC). GaAs exposure had no effect on host resistance to Plasmodium yoelii or Streptococcus pneumoniae, but dose dependently increased resistance of the mouse to Listeria monocytogenes. Treated mice demonstrated a significantly decreased resistance to the B16F10 melanoma with a sevenfold increase in tumor burden at 200 mg/kg. GaAs affects both humoral and cellular immune parameters in mice and impairs the ability of the immune system to protect against B16F10 tumor challenge.

Animals↗
PubMed1986

Metabolism and excretion of orally and intraperitoneally administered gallium arsenide in the hamster.

This study deals with the metabolism of gallium arsenide (GaAs). GaAs was shown to be soluble in various media. Since this compound could dissolve in aqueous solvents, in vivo dissolution was investigated. Hamsters were used to study the dissolution and subsequent pharmacokinetics of any liberated arsenic species. The fecal and urinary excretion data following oral and intraperitoneal administration showed that GaAs, when administered orally, is mostly excreted in the feces but poorly in the urine, and that the compound, when administered intraperitoneally, is poorly excreted in both the feces and urine. Analysis of tissues for arsenic levels yielded concentrations in the ppb range, which further verified this fact. Most interesting was the fact that dimethylarsinic acid (DMAA) and methylarsonic acid (MAA) along with inorganic arsenic were found in the urine and tissues. GaAs was shown to dissolve in vivo and the released arsenic species were metabolized as other inorganic arsenics were found in the urine and tissues. GaAs was shown to dissolve in vivo and the released arsenic species were metabolized as other inorganic arsenic containing compounds. The low solubility and poor oral absorption may make this compound less toxic than other inorganic arsenic compounds.

Administration, Oral↗
PubMed1994

Killing of cariogenic bacteria by light from a gallium aluminium arsenide diode laser.

Suspensions of Streptococcus mutans, S. sobrinus, Lactobacillus casei and Actinomyces viscosus were exposed to light from a gallium aluminium arsenide laser in the presence of aluminium disulphonated phthalocyanine and the numbers of survivors determined. Exposure to the laser light in the absence of the dye, or the dye in the absence of the laser light, had no significant effect on the viability of the organisms. However, a light-dose-related decrease in the viable count of all four target organisms was found on exposure to the laser light in the presence of the dye. The kills attributable to lethal photosensitization amounted to approximately 10(6) CFU in the case of each organisms. As appreciable kills were achieved within clinically convenient exposure times (30-90 s), these results imply that lethal photosensitization may be a useful technique for eliminating bacteria from carious lesions prior to restoration.

Actinomyces viscosus↗
PubMed1987

Use of gallium, colloids and pertechnetate as carriers of drugs for selective action.

A pharmacodynamic hypothesis is formulated which considers using substances such as gallium, with predilection to locate in neoplasm and inflammation, to increase the therapeutic effect in the disease-affected area. Drugs carried by a colloid can be directed to the liver, IDA derivatives which are metabolized by hepatocytes can also be used as transporters of drugs to the liver and to the hepatobiliary tree because they are eliminated through that route. In diseases which affect the blood-brain barrier substance such as pertechnetate can be used as drug carriers. Pertechnetate and other substances which are eliminated through the kidneys may be used as carriers for drugs in certain renal diseases. This therapeutic approach can be used if the amount of carrier is not toxic to the target organ, if the time of action is sufficient and if the bond between drug and carrier is strong.

Brain↗
PubMed1986

On the mechanism of gallium accumulation in tumours. Isolation of N-hydroxypeptides.

With the use of A SEP-PAK Alumina N cartridge, peptide fractions containing the hydroxamate moiety have been isolated from tumour-tissue homogenate. It is therefore postulated that N-hydroxypeptides might play a role in the accumulation of gallium-67 in tumours. The biodistribution of several 67Ga-labelled hydroxamate peptide fractions is determined. Although their biodistribution differs from that of 67Ga-citrate no enhancement in tumour accumulation is observed indicating that they do not act like tumour-specific siderophores.

Animals↗
PubMed1992

Potential 67Ga radiopharmaceuticals for myocardial imaging: tris(1-aryl-3-hydroxy-2-methyl-4-pyridinonato)gallium(III) complexes.

A series of highly lipophilic complexes of 1-aryl-3-hydroxy-2-methyl-4-pyridinones with gallium(III)-67 has been evaluated in vitro and in vivo as potential radiopharmaceuticals. The pyridinones have different substituents at the para-position of the phenyl ring: R = H, CH3, OCH3 and NO2. Biodistribution studies of 67Ga complexes have been carried out in rabbits, mice, rats and a dog. High heart uptake of the radionuclide has been shown in rabbits and the dog. The different biodistribution patterns in mice and rats indicate that there is a species difference in the biodistribution of these complexes. Rabbits and the dog show rapid heart uptake and blood clearance. The speciation of the Ga3+ ion in vivo is simulated in vitro with a simple blood plasma model based on the available thermodynamic data.

Animals↗
PubMed1992

A comparison of gallium-67 single photon emission computed tomography and computed tomography in mediastinal Hodgkin's disease.

The role of gallium-67 single photon emission computed tomography (Ga-67 SPECT) in the assessment of mediastinal Hodgkin's disease was evaluated prospectively. Ga-67 SPECT and computed tomography (CT) were compared and correlated with clinical findings at initial presentation in 30 patients, 6 weeks after treatment, and 6 months later in 20 of the 30 patients. At initial presentation, active disease was detected on both imaging modalities on all occasions. 6 weeks after treatment CT showed residual mediastinal abnormality in 7 patients, whereas Ga-67 SPECT showed abnormal mediastinal tracer uptake in 3 patients. 6 months later CT showed residual mediastinal abnormality in 5 patients whereas all the Ga-67 SPECT studies were negative. Ga-67 SPECT imaging is a useful tool in assessing response to therapy in mediastinal Hodgkin's disease.

Adult↗
PubMed2004

Gallium(III) adsorption on carbonates and oxides: X-ray absorption fine structure spectroscopy study and surface complexation modeling.

Adsorption of Ga on calcite, magnesite, amorphous silica, and manganese oxide as a function of pH and gallium concentration in solution was studied using a batch adsorption technique. Adsorbed complexes of Ga on calcite, magnesite, and delta-MnO2 were further characterized using XAFS spectroscopy. At high surface loadings from supersaturated solutions, Ga is likely to form a polymeric network at the surface (edge- and corner-sharing octahedra). At low surface loadings, Ga presents as isolated octahedra, probably attached to the Me-O sites on the surface, and coordinated by water molecules and hydroxide groups at 1.90-1.94 A. At pH>6, Ga therefore changes its coordination from 4 to 6 when adsorbing from solution (Ga(OH)(-)4(aq)) onto metal surface sites (MeOGa(OH)n(H2O)2-n(5-n), Me = Ca, Mg, or Mn, and n=1 and 2 for carbonate minerals and MnO2, respectively). Because the EXAFS is not capable of seeing hydrogen atoms, the protonation of surface complexes was determined by fitting the experimental pH-dependent Ga adsorption edge. A surface complexation model which assumes the constant capacitance of the electric double layer (CCM) and postulates the formation of positively charged, neutral and negatively charged surface complexes for carbonates, manganese oxide and silica, respectively, was used to describe the dependence of adsorption equilibria on aqueous solution composition in a wide range of pH and Ga concentration.

Adsorption↗
PubMed2004

Gallium arsenide exposure impairs processing of particulate antigen by macrophages: modification of the antigen reverses the functional defect.

Gallium arsenide (GaAs), a semiconductor used in the electronics industry, causes systemic immunosuppression in animals. The chemical's impact on macrophages to process the particulate antigen, sheep red blood cells (SRBC), for a T cell response in culture was examined after in vivo exposure of mice. GaAs-exposed splenic macrophages were defective in activating SRBC-primed lymph node T cells that could not be attributed to impaired phagocytosis. Modified forms of SRBC were generated to examine the compromised function of GaAs-exposed macrophages. SRBC were fixed to maintain their particulate nature and subsequently delipidated with detergent. Delipidation of intact SRBC was insufficient to restore normal antigen processing in GaAs-exposed macrophages. However, chemically exposed cells efficiently processed soluble sheep proteins. These findings suggest that the problem may lie in the release of sequestered sheep protein antigens, which then could be effectively cleaved to peptides. Furthermore, opsonization of SRBC with IgG compensated for the macrophage processing defect. The influence of signal transduction and phagocytosis via Fcgamma receptors on improved antigen processing could be dissociated. Immobilized anti-Fcgamma receptor antibody activated macrophages to secrete a chemokine, but did not enhance processing of unmodified SRBC by GaAs-exposed macrophages. Restoration of normal processing of particulate SRBC by chemically exposed macrophages involved phagocytosis through Fcgamma receptors. Hence, initial immune responses may be very sensitive to GaAs exposure, and the chemical's immunosuppression may be averted by opsonized particulate antigens.

Animals↗
PubMed2005

Gallium-68-DOTA-albumin as a PET blood-pool marker: experimental evaluation in vivo.

Investigations into tumor angiogenesis and antiangiogenic treatment have renewed interest in tumor perfusion. To image tumor blood-pool by PET, suitable tracers are not generally available. In this experimental study, we characterized a 68Ga-labeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugate of rat serum albumin (68Ga-DOTA-RSA) in vivo using a generator-produced isotope. Biodistribution was determined in ACI rats after intravenous administration of 3-6 MBq of 68Ga-DOTA-RSA. Three ACI rats were imaged over 1 h by dynamic PET after intravenous administration of 15-25 MBq of 68Ga-DOTA-RSA while the blood-pool activity was recorded simultaneously in a closed extracorporeal loop (ECL) between the carotid artery and the jugular vein. Time-activity curves (TACs) were obtained from volume of interest (VOI) analysis and from the ECL data. Stability and metabolites in plasma and urine were analyzed by size exclusion HPLC (SE-HPLC) 1 h after intravenous injection of 67Ga-DOTA-RSA. Blood radioactivity decreased by 10% and 18% from 10 to 60 min p.i. by biodistribution and PET or ECL, respectively. Tissue sampling between 10 and 60 min p.i. showed slight increases in the uptake of spleen, myocardium, kidney and skeletal muscle while hepatic accretion remained unchanged. Total urinary excretion after 60 min amounted to 9% of the injected dose. HPLC demonstrated a single urinary metabolite corresponding in size to gallium-labeled DOTA. 68Ga-DOTA-RSA is a blood-pool tracer whose physical and biological half-life is well suited for PET. Our findings support clinical imaging using 68Ga-DOTA-labeled human serum albumin (HSA). The generator-produced label makes 68Ga-DOTA-labeled albumin continuously available even to centers lacking an in-house cyclotron.

Animals↗
PubMed1979

The roles of Gallium-67 scintigraphy, ultrasonography, and computed tomography in the detection of abdominal abscesses.

The evaluation of patients with suspected abdominal abscesses begins with a history and careful physical examination. Gallium-67 (67Ga) scintigraphy, ultrasonography (US), and computed tomography (CT) are utilized only after other routine investigations have failed to localize the abscess. All three modalities are reliable for the detection of abdominal abscesses. The decision regarding which of these three diagnostic tests to use in a particular patient rests upon clinical considerations. If the patient has acute localizing signs and symptoms, 67Ga should not be used initially. In this type of patient, rapid diagnosis is best provided by either US or CT. Further radiologic investigation may be terminated if the CT or US findings are characteristic of an abscess. A 67Ga scan should be performed in a patient with acute localizing signs and symptoms if the initial CT or US is negative. In a patient with nonlocalizing signs and symptoms, 67Ga imaging should be employed as the first procedure since the entire body is easily surveyed. If the 67Ga images are abnormal, then CT or US should be utilized for further lesion characterization. This diagnostic approach will optimize the rapidity of patient evaluation and will minimize diagnostic errors.

Abdomen↗