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PubMed1999

Gallium replication in aquatic and nonaquatic organism scanning electron microscopy.

A technique using pure gallium metal as a replication material is reported for biological surface scanning electron microscopy (SEM). The technique first directly enables aquatic organisms in water to be replicated due to gallium's low melting point and, second, reproduces surface structures and images of the two-dimensional (2D) distribution of substances transferred from the original surface to the gallium surface due to gallium's high surface tension. An aquatic protozoan in water was directly replicated to show its typical surface structures. The technique was then used to visualize human hair surface structures and 2D transferred substance distribution using X-ray microanalysis.

Animals↗
PubMed2000

Novel gallium(III) complexes transported by MDR1 P-glycoprotein: potential PET imaging agents for probing P-glycoprotein-mediated transport activity in vivo.

BACKGROUND: Multidrug resistance (MDR) mediated by expression of MDR1 P-glycoprotein (Pgp) represents one of the best characterized barriers to chemotherapy in cancer patients. Positron emission tomography (PET) agents for analysis of Pgp-mediated drug transport activity in vivo would enable noninvasive assessment of chemotherapeutic regimens and MDR gene therapy. RESULTS: Candidate Schiff-base phenolic gallium(III) complexes were synthesized from their heptadentate precursors and gallium(III)acetylacetonate. Crystal structures demonstrated a hexacoordinated central gallium with overall trans-pseudo-octahedral geometry. Radiolabeled (67)Ga-complexes were obtained in high purity and screened in drug-sensitive (Pgp(-)) and MDR (Pgp(+)) tumor cells. Compared with control, lead compound 6. demonstrated antagonist-reversible 55-fold lower accumulation in Pgp-expressing MDR cells. Futhermore, compared with wild-type control, quantitative pharmacokinetic analysis showed markedly increased penetration and retention of 6. in brain and liver tissues of mdr1a/b((-/-)) gene disrupted mice, correctly mapping Pgp-mediated transport activity at the capillary blood-brain barrier and hepatocellular biliary cannalicular surface in vivo. CONCLUSIONS: These results indicate that gallium(III) complex 6. is recognized by MDR1 Pgp as an avid transport substrate, thereby providing a useful scaffold to generate (68)Ga radiopharmaceuticals for molecular imaging of Pgp transport activity in tumors and tissues in vivo using PET.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1986

Thermodynamics of gallium complexation by human lactoferrin.

Equilibrium constants for the successive binding of 2 equiv of Ga3+ to human lactoferrin have been measured by difference ultraviolet spectroscopy in 0.1 M 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid containing 5 mM bicarbonate at pH 7.4 and 25 degrees C. Ethylenediamine-N,N'-diacetic acid was used as the competing chelating agent. Values of the effective binding constants for the stated experimental conditions are log K1 = 21.43 +/- 0.18 and log K2 = 20.57 +/- 0.16. Comparison of these results with literature values for the gallium-transferrin binding constants indicates that lactoferrin binds gallium more strongly by a factor of approximately 90. The ratios of successive binding constants for the two proteins are essentially identical. A linear free energy relationship (LFER) for the complexation of gallium(III) and iron(III) has been prepared and used to estimate an iron(III)-lactoferrin binding constant for pH 7.4. The LFER prediction is compared with thermodynamic data on iron binding at pH 6.4 and gallium binding at pH 7.4. The results indicate that the ratio of iron binding constants for lactoferrin and transferrin is likely in the range of 50-90.

Gallium↗
PubMed1993

Assessment of arsenic exposures and controls in gallium arsenide production.

The electronics industry is expanding the use of gallium arsenide in the production of optoelectronic devices and integrated circuits. Workers in the electronics industry using gallium arsenide are exposed to hazardous substances such as arsenic, arsine, and various acids. Arsenic requires stringent controls to minimize exposures (the current OSHA PEL for arsenic is 10 micrograms/m3 and the NIOSH REL is 2 micrograms/m3 ceiling). Inorganic arsenic is strongly implicated in respiratory tract and skin cancer. For these reasons, NIOSH researchers conducted a study of control systems for facilities using gallium arsenide. Seven walk-through surveys were performed to identify locations for detailed study which appeared to have effective controls; three facilities were chosen for in-depth evaluation. The controls were evaluated by industrial hygiene sampling. Including personal breathing zone and area air sampling for arsenic and arsine; wipe samples for arsenic also were collected. Work practices and the use of personal protective equipment were documented. This paper reports on the controls and the arsenic exposure results from the evaluation of the following gallium arsenide processes: Liquid Encapsulated Czochralski (LEC) and Horizontal Bridgeman (HB) crystal growing, LEC cleaning operations, ingot grinding/wafer sawing, and epitaxy. Results at one plant showed that in all processes except epitaxy, average arsenic exposures were at or above the OSHA action level of 5 micrograms/m3. While cleaning the LEC crystal pullers, the average potential arsenic exposure of the cleaning operators was 100 times the OSHA PEL. At the other two plants, personal exposures for arsenic were well controlled in LEC, LEC cleaning, grinding/sawing, and epitaxy operations.

Air Pollutants, Occupational↗
PubMed1989

Clinical value of gallium-67 scintigraphy in the investigation of fever or inflammation of unknown origin in the ultrasound and computed tomography era.

Gallium scintigraphy was performed in 54 consecutive patients hospitalized for exploration of fever or inflammation of unknown origin, in whom thorough initial exploration did not yield any clue. Only in 28 patients (51.8%) could a definite diagnosis be established. The positive gallium scintigraphy results were clinically rated as valuable, questionable or valueless according to their contribution to the diagnosis. Gallium scintigraphy was positive in 22 patients (40%) and deemed valuable in 13 patients (24%). A final diagnosis could be ascertained in 77% of the cases with a positive scintigram. In contrast a cause of fever or inflammation was found only in 34% of the cases with a negative scintigram. Gallium scintigraphy is valuable as an early localizing investigation rather than a last resort test in patients with fever or inflammation of unknown origin. A positive scintigram increases the chances of establishing a final diagnosis.

Evaluation Studies as Topic↗
PubMed2004

Separation of gallium and arsenic from the wafer grinding extraction solution.

This work investigates the separation of gallium and arsenic from the wafer grinding extraction solution. The wafer grinding extraction solution was generated using hot and concentrated nitric acid. In this study, adsorption technology was employed to remove the toxic arsenic from the extraction solution. Ferric hydroxide was the adsorbent employed to adsorb arsenic. The effects of pH value, contact time, absorbent dosage, and chloride ion concentration on the efficiency of adsorption of gallium and arsenic were investigated. The optimal conditions for recovering gallium and removing arsenic were a raw pH of 0.2, a contact time of 6min and a ferric hydroxide concentration of 30.4g/L. Additionally, adding chloric ions reduces the residual percentage of gallium (ReGa) and the percentage of arsenic removed (RAs). Under these optimal conditions, ReGa and RAs are 100 and 80%, respectively.

Adsorption↗
PubMed1998

Paclitaxel plus gallium nitrate and filgrastim in patients with refractory malignancies: a phase I trial.

To determine the maximally tolerated dose of paclitaxel with and without filgrastim (G-CSF) when administered as a 24-hour intravenous infusion after a 120-hour infusion of gallium nitrate at a fixed dose of 300 mg/m2/24 hours, 40 patients were entered onto a trial lasting from September 1994 to September 1996. Eligibility included a diagnosis of an advanced malignancy not amenable to curative therapy and up to one previous chemotherapy regimen for metastatic disease. Gallium was administered at a fixed dose of 300 mg/m2/day as a continuous intravenous infusion for 120 hours. Paclitaxel starting at 90 mg/m2 was given concurrently with the last 24 hours of the gallium as a 24-hour intravenous infusion. Cycles were repeated every 21 days. Once the maximum tolerated dose (MTD) of paclitaxel was reached, G-CSF (5 microg/kg/day days 7-16) was added and paclitaxel dose escalation continued. The MTD for paclitaxel without G-CSF was 110 mg/m2 and 225 mg/m2 with G-CSF, with neutropenia being the dose-limiting toxicity. A partial response was noted in a patient who had thymoma and a complete response was achieved in a patient who had colon cancer. The recommended phase II dosage is gallium nitrate at 300 mg/m2/day over 120 hours, with paclitaxel at 110 mg/m2 over 24 hours without G-CSF or 225 mg/m2 over 24 hours with G-CSF and 0.5 mg calcitriol on days 1 through 7. Further trials of this modified regimen for outpatient administration are in progress.

Adult↗
PubMed1992

The efficacy of gallium scintigraphy in detecting malignant soft tissue neoplasms.

A prospective study was conducted on 55 consecutive patients to evaluate the efficacy of gallium scintigraphy in detecting malignancy in any soft tissue mass. It was determined that gallium scintigraphy could detect malignancy with a sensitivity of 96% and a specificity of 87%. Large and small sarcomas, irrespective of their fascial location, were identifiable by gallium imaging. Occult, nonpulmonary sites of disseminated disease were detected in 13%. Gallium scintigraphy proved to be a reliable predictor of malignancy for all soft tissue masses, but because of its cost, it must be used judiciously.

Adolescent↗
PubMed1999

Gallium scanning in the diagnosis and management of orbital lymphoma: a case report.

PURPOSE: To illustrate the utility of gallium scintigraphy in the diagnosis and management of orbital lymphoma. METHODS: A patient with an orbital lymphoma is reported. The results of the computed tomography scan and gallium scan are reviewed. RESULTS: Although the orbital lymphoma was readily visible on the gallium scan, it was poorly visualized on the computed tomography scan, which was interpreted as normal. CONCLUSION: Gallium scanning is a valuable adjunct in the diagnosis and management of orbital and systemic lymphoma.

Aged↗
PubMed1980

Effect of hemodialysis on gallium-67-citrate scanning.

Gallium-67-citrate scanning is often used in the diagnosis of inflammatory processes in hemodialysis patients. The question arises whether the dialysis process will adversely affect the quality of the gallium scan. To answer this question, nine dialysis patients were studied, eight on hollow-fiber dialysis units and one on ultrafiltration, in an attempt to quantitate the loss of gallium through dialysis. Blood sampling during dialysis failed to demonstrate changes in gallium concentration attributable to removal by dialysis. Sampling of dialysate demonstrated levels of activity significantly greater than background; however, quantitation was not reliable. Ultrafiltration with total collection of extracted fluids yielded 0.5% of injected dose removed from the blood. Whole-body scans at 24 hours postinjection showed good quality and total counts unaltered by dialysis. The time of injection prior to dialysis also showed no effect on the quality of the final image.

Citrates↗
PubMed1982

Gallium scans in Paget's sarcoma.

Bone and gallium scans were performed in twelve patients with Paget's sarcoma. Most of these patients had polyostotic Paget's disease. The lesions with sarcomatous changes were usually associated with less Tc-99m MDP uptake as compared with Pagetoid bone which was not sarcomatous. Gallium uptake in the tumor area was proportionally higher than the MDP uptake and appeared quite irregular. Follow-up scans were available in a limited number of patients. Temporary response to chemotherapy was reflected by the decreased gallium uptake in the tumor area. Gallium scans appear to be useful in confirming the diagnosis of Paget's sarcoma and may be valuable in monitoring therapeutic response.

Aged↗
PubMed1983

Renal gallium accumulation in the absence of renal pathology in patients with severe hepatocellular disease.

Visualization of Ga-67 citrate in the kidneys at 48 hours and 72 hours post injection is usually interpreted as evidence of renal pathology. In reviewing approximately 200 consecutive patients referred for gallium scans, 40 patients who also underwent liver/spleen Tc-99m sulfur colloid (SC) studies within one month of the gallium study were identified. Fourteen of these patients showed advanced hepatocellular dysfunction on the Tc-99m SC liver/spleen images. Of these 14 patients, nine had persistent renal accumulation of gallium at 48 or 72 hours. Five of these nine patients had no evidence of primary renal disease by clinical or postmortem examination and subsequent clinical information indicated that two additional patients probably had no significant renal pathology. Therefore, bilateral symmetrically increased renal uptake of gallium in patients with advanced hepatocellular disease should not necessarily be interpreted as evidence of renal pathology.

Adult↗
PubMed1987

The usefulness of gallium-67 citrate scanning in testicular seminoma.

An analysis of 77 consecutive patients with a histologic diagnosis of seminoma testis, assessed and treated at the Cross Cancer Institute between 1977 and 1982, is presented. Ga-67 citrate was first used in the assessment of patients with malignant testicular tumors in 1973. Following three years of study that supported the observation of the gallium-avid nature of seminoma, gallium scans became routine in the initial staging assessment and were used also when recurrence was suspected. From 1977 through 1982, 72 patients with biopsy-proven seminoma testis were assessed initially for extent of disease by Ga-67 scanning. Comparison with intravenous pyelography and bipedal lymphography was possible for accuracy of tumor assessment. The scan sensitivity was 83%, and the specificity was 95%. During the same period, gallium was studied in nonseminomatous testicular tumors but the results were disappointing and its use was discontinued. The gallium-avid nature of seminoma testis may be useful in determining the extent of disease.

Dysgerminoma↗
PubMed1988

Abnormal gallium uptake in anticardiolipin syndrome: an unexplained phenomenon.

A case of asymmetrical gallium uptake in the musculature of a young woman with anticardiolipin syndrome is reported. The patient was asymptomatic in the areas of involvement, muscle biopsy was normal, and the abnormal gallium accumulation was unchanged on repeat evaluation 7 months later. Possible causes for the abnormal gallium uptake are proposed, but the mechanisms of uptake in this case remain unclear. Nuclear physicians should be aware of this disorder and the potential for abnormal gallium uptake with this syndrome.

Adult↗
PubMed1988

Hepatic photopenia in gallium imaging.

Although Ga-67 has been used extensively in imaging many different conditions, much is yet unknown about the mechanisms by which gallium concentrates preferentially in tissues such as the liver. This paper reports three patients with markedly diminished hepatic uptake of gallium. The cases are examined in light of published data demonstrating such factors as transferrin levels, radiation, and chemotherapeutic agents as altering the hepatic uptake of gallium. Of the many factors believed to influence the biodistribution of gallium, none can definitively account for the lack of hepatic uptake in these patients.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Cutaneous gallium uptake in patients with AIDS with mycobacterium avium-intracellulare septicemia.

Gallium imaging is increasingly being used for the early detection of complications in patients with AIDS. A 26-year-old homosexual man who was HIV antibody positive underwent gallium imaging for investigation of possible Pneumocystis carinii pneumonia. Widespread cutaneous focal uptake was seen, which was subsequently shown to be due to mycobacterium avium-intracellulare (MAI) septicemia. This case demonstrates the importance of whole body imaging rather than imaging target areas only, the utility of gallium imaging in aiding the early detection of clinically unsuspected disease, and shows a new pattern of gallium uptake in disseminated MAI infection.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Gallium accumulation in early pulmonary Pneumocystis carinii infection.

The accumulation of gallium 67 citrate in pulmonary Pneumocystis carinii is well known. The sensitivity of gallium uptake in detecting early inflammatory processes, even when conventional roentgenograms are normal, would seem to make it possible in immunocompromised patients to make a presumptive diagnosis of this serious infection early in its course without using invasive techniques to demonstrate the organism. However, the presence of gallium uptake in radiation pneumonitis, pulmonary drug toxicity, and other processes that also occur in this group limit its usefulness. In our two patients--a young woman with Hodgkin's disease and an elderly woman with small cell lung cancer--this technique proved helpful. Although the latter patient was successfully treated empirically, such empiric treatment should be reserved for patients unable or unwilling to undergo invasive tests. Pulmonary gallium uptake in patients with respiratory symptoms, even with a normal chest film, should prompt attempts to directly demonstrate the organism.

Adult↗
PubMed2006

Antimicrobial activity of gallium against virulent Rhodococcus equiin vitro and in vivo.

Rhodococcus equi, a facultative intracellular bacterium, causes severe pneumonia in foals. Evidence suggests that most foals become infected very early in life, when they have immature or ineffective innate immune responses. This study evaluated the antimicrobial activity of gallium against R. equi, as a potential chemoprophylactic and therapeutic agent. Rhodococcus equi was grown in media with various concentrations of gallium nitrate (GN), with and without excess iron. GN significantly inhibited growth and killed R. equi, and these effects were abolished with excess iron. Antimicrobial effects of Ga appear to be related to its interference with iron metabolism. Mice were treated orally with gallium maltolate (GaM), 10 or 50 mg/kg BW, or distilled H2O prior to and after experimental infection with R. equi. Six days post-infection, organs were harvested and R. equi concentrations assessed, and serum gallium concentrations determined. GaM was absorbed in a dose-dependent manner, and R. equi tissue burdens were greater in control mice than in all GaM-treated mice. GaM may aid in the control of disease by preventing development of overwhelming R. equi tissue burdens prior to the establishment of requisite innate and adaptive immune responses.

Actinomycetales Infections↗