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PubMed2007

A new class of binuclear gallium hydrides: synthesis and properties of [{GaCl(hpp)H}2] (hpp=1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidate).

Herein we report on the synthesis and characterization of the first representative of a new class of gallium hydrides, namely [{GaCl(hpp)H}2] (hpp=1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidate). Our X-ray diffraction data suggest the presence of weak H--H contacts between adjacent [{GaCl(hpp)H}2] molecules in the crystal. With the aid of quantum-chemical calculations, the pathway of its formation starting with the adduct H2ClGaNMe3 and the pyrimidine hppH were analyzed. [{GaCl(hpp)H}2] slowly decomposes at 25 degrees C, a process which presumably leads under H2 elimination to [{GaCl(hpp)}2]. Although we were not yet able to characterize [{GaCl(hpp)}2] experimentally, DFT calculations provide information about its likely structure. According to these calculations, the molecule features a Ga--Ga single bond.

Journal Article↗
PubMed2002

Acute electrophysiologic effect of pulsed gallium-arsenide low energy laser irradiation on configuration of compound nerve action potential and nerve excitability.

BACKGROUND AND OBJECTIVES: We evaluated the acute electrophysiologic effects of low-energy pulsed laser irradiation, measured by extracellular recording technique on compound action potential configuration and nerve excitability in the isolated frog sciatic nerve STUDY DESIGN/MATERIALS AND METHODS: A pulsed gallium-arsenide (GaAs) laser (wavelength, 904 nm; pulse duration, 220 nanoseconds; peak power per pulse, 27 W; spot size, 0.28 cm(2); total applied energy density, 0.005-2.5 J/cm(2)) was used for the experiment. Sixty isolated nerves were divided into six groups (n = 10), each of which received a different repetition frequency. In each group, action potentials were recorded, before laser irradiation, which served as the control data. The extracellular action potentials were recorded for each combination of 1, 3, 5, 7, 10, 13, and 15 minutes of irradiation time and 4, 8, 16, 32, 64, 128 repetition frequency by using a BIOPAC MP 100 Acquisition System Version 3.5.7 (Santa Barbara USA). Action potential latency, duration of depolarization and repolarization, and the stimulating voltage were measured. Statistical evaluation was performed using linear correlation analysis by SPSS 9.05. RESULTS: Although there was no correlation between applied energy density and action potential latency, the duration of depolarization and repolarization phases (P > 0.05), there was a weak correlation between applied energy density and stimulating voltage. CONCLUSIONS: The study showed that low-energy GaAs irradiation at 42 different energy density between 0.005 and 2.5 J/cm(2) generates no effect on action potential configuration and nerve excitability.

Action Potentials↗
PubMed1987

Laser modulation of human immune system: inhibition of lymphocyte proliferation by a gallium-arsenide laser at low energy.

Cultured human lymphocytes were subjected to irradiation with a gallium-arsenide laser at energy fluence varying from 2.17 to 651 mJ/cm2, and the cell proliferation was assessed by [3H]thymidine incorporation. Both mitogenic proliferation in response to phytohemagglutinin and spontaneous cell proliferation were markedly inhibited by the laser irradiation at energy fluence as low as 10.85 mJ/cm2. Similarly, the functional response of cells to antigen stimulation in a one-way mixed-lymphocyte reaction was also diminished as a result of laser irradiation. The results indicate that laser irradiation at low energy can interfere with immune system in vitro, and similar modulation could potentially occur in human subjects exposed to laser irradiation in vivo.

Dose-Response Relationship, Radiation↗
PubMed2004

Efficacy of 904 nm gallium arsenide low level laser therapy in the management of chronic myofascial pain in the neck: a double-blind and randomize-controlled trial.

BACKGROUND AND OBJECTIVES: A prospective, double-blind, randomized, and controlled trial was conducted in patients with chronic myofascial pain syndrome (MPS) in the neck to evaluate the effects of infrared low level 904 nm Gallium-Arsenide (Ga-As) laser therapy (LLLT) on clinical and quality of life (QoL). STUDY DESIGN/PATIENTS AND METHODS: The study group consisted of 60 MPS patients. Patients were randomly assigned to two treatment groups: Group I (actual laser; 30 patients) and Group II (placebo laser; 30 patients). LLLT continued daily for 2 weeks except weekends. Follow-up measures were evaluated at baseline, 2, 3, and 12 weeks. All patients were evaluated with respect to pain at rest, pain at movement, number of trigger points (TP), the Neck Pain and Disability Visual Analog Scale (NPAD), Beck depression Inventory (BDI), and the Nottingham Health Profile (NHP). RESULTS: In active laser group, statistically significant improvements were detected in all outcome measures compared with baseline (P < 0.01) while in the placebo laser group, significant improvements were detected in only pain score at rest at the 1 week later of the end of treatment. The score for self-assessed improvement of pain was significantly different between the active and placebo laser groups (63 vs. 19%) (P < 0.01). CONCLUSION: This study revealed that short-period application of LLLT is effective in pain relief and in the improvement of functional ability and QoL in patients with MPS.

Adult↗
PubMed2004

Tetrahedral homonuclear organoelement clusters and subhalides of aluminium, gallium and indium.

This review is focused on the synthesis and the reactivity of tetrahedral organoelement clusters of the heavier elements of third main-group aluminium, gallium, and indium, which have been known for about a decade. They possess the elements in an unusually low oxidation state of +1 and have direct element--element interactions between their four constituents. Each cluster atom is further attached to one terminal and in most cases a bulky organic substituent, which prevents disproportionation by steric shielding. The synthesis of these compounds succeeds by different methods such as the reduction of suitable organoelement(III) halides with alkali metals and magnesium or the treatment of element(I) halides with lithium organyls. They are deeply coloured, and their bonding situation may best be described by delocalized molecular orbitals. They show a singular chemical reactivity, which results in the formation of many secondary products possessing unprecedented structures and properties. The synthesis of organoelement subhalides still containing the elements in low oxidation states is discussed in more detail in the second part of this review. These compounds are easily accessible by the careful oxidation of the clusters with halogen donors such as hexachloroethane or with AlX(3)/X(2) mixtures. They produce dimers via halogen bridges, but in certain cases monomers were observed even for the solid state. They are very effective starting compounds for secondary reactions and the generation of new products containing the elements in unusual oxidation states by salt-elimination reactions, for instance.

Journal Article↗
PubMed2002

Acute electrophysiological effect of pulsed gallium-arsenide low-energy laser irradiation on isolated frog sciatic nerve.

We evaluated the acute electrophysiological effects of low-energy pulsed laser irradiation on isolated frog sciatic nerve measured by extracellular recording technique. A pulsed gallium-arsenide (GaAs) laser (wavelength: 904 nm, pulse duration 220 ns, peak power per pulse: 27W, spot size: 0.28 cm(2), total applied energy density: 0.005-2.5J/cm(2)) was used for the experiment. Sixty isolated nerves were divided into six groups (n=10), each of which received a different laser dose. In each group, action potentials were recorded before laser irradiation which served as the control data. The extracellular action potentials were recorded for each combination of 1, 3, 5, 7, 10, 13 and 15 minutes of irradiation time and 4, 8, 16, 32, 64 and 128 repetition frequency by using a BIOPAC MP 100 Acquisition System Version 3.5.7 (Santa Barbara, USA). Action potential amplitude, area, duration and conduction velocity were measured. Statistical evaluation was performed using repeated measures variance analysis by SPSS 9.0. There were no statistically significant differences for action potential amplitude, area and conduction velocity among the laser groups and control data (p>0.05). The study showed that low-energy GaAs irradiation at 4-128 Hz repetition frequencies administered for irradiation times of 1-15 min generates no effect on action potential amplitude, area, duration and conduction velocity in isolated frog sciatic nerve.

Action Potentials↗
PubMed2006

Zonal differences in gallium-67 uptakes between perivenous versus periportal regions of rat liver following carbon tetrachloride treatment.

Gallium-67 ((67)Ga) has been used as a tumor or inflammation-imaging agent in nuclear medicine, although underlying mechanism has not been fully elucidated. To gain some insights into the mechanism of (67)Ga uptake by injured liver, we analyzed the difference between perivenous and periportal regions of rat liver in terms of (67)Ga uptake by hepatocytes at the site of inflammation caused by carbon tetrachloride (CCl(4))-treatment. Distribution of (67)Ga in rat liver sections was monitored with a BAS5000 system following hepatic injury by CCl(4)-treatment. Periportal hepatocytes (PPH) and perivenous hepatocytes (PVH) were prepared by modified digitonin-collagenase perfusion technique. Uptakes of (67)Ga in PVH region and PPH region reached to a maximum 2 days after CCl(4)-treatment, and the amount of maximum uptake of (67)Ga in PVH was twice as much as that in PPH. Liver damage as measured by lipid peroxidation and (45)Ca uptake occurred in PVH region within 1 day after CCl(4)-treatment. Incorporation of bromodeoxyuridine into hepatocytes reached to a maximum 2 days after CCl(4)-treatment, and peaked amount of DNA synthesis in PVH was twice as much as that in PPH. These results indicated that the uptake of (67)Ga by the PVH region was carried out during hepatic regeneration phase rather than hepatic damage period by CCl(4)-treatment.

Journal Article↗
PubMed1988

Gallium-67 scanning in the clinical evaluation of human immunodeficiency virus infection: indications and limitations.

This review, examines the indications for and limitations of gallium-67 (67Ga) scanning in the evaluation of patients infected with human immunodeficiency virus (HIV). The imaging protocol, as well as the normal biodistribution of 67Ga and its normal variants are discussed. The diagnostic significance of the different scintigraphic patterns that are found in acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC) patients is reviewed. The use of 67Ga scintigraphy for measurement of the effectiveness of treatment in this patient population is also discussed, as is the likelihood that this examination could be used as a prognostic indicator in the future.

AIDS-Related Complex↗
PubMed1997

Sonodynamically induced antitumor effect of gallium-porphyrin complex by focused ultrasound on experimental kidney tumor.

The antitumor effect of a gallium-porphyrin complex, ATX-70, induced by focused ultrasound, on colon 26 carcinoma implanted in a mouse kidney was investigated. Colon 26 tumors were exposed to focused ultrasound at 500 kHz and 1 MHz in a progressive wave mode. Both frequency components were superimposed onto each other in the focal zone to efficiently produce cavitation in the tumor. ATX-70 was administered intravenously at the dose of 2.5 mg/kg, 24 h before the ultrasonic exposure. Antitumor effects were evaluated by histological observation 7 days after the exposure. The destruction of tumor tissue was observed with the ultrasonic treatment in combination with ATX-70, while neither the treatment with ATX-70 alone nor that with ultrasound alone caused any necrosis. These results first demonstrated that antitumor effects of a porphyrin compound can be induced by focused ultrasound in a progressive wave mode.

Animals↗
PubMed2000

Gallium-desferrioxamine protects the cat retina against injury after ischemia and reperfusion.

This study sought to determine whether gallium-desferrioxamine (Ga/DFO) can curb free radical formation and mitigate biochemical and electrophysiological parameters of injury in the cat retina subjected to ischemia followed by reperfusion. For the biochemical studies, cat eyes were subjected to 90 min of retinal ischemia followed by 5 min of reperfusion, and enucleation of one eye of each cat was used to measure retinal reperfusion injury. Before enucleation of fellow eyes, 2.5 mg/kg Ga/DFO was injected intravenously 5 min before reperfusion. The flux of hydroxyl radicals, as measured directly by conversion of salicylate to 2,3- and 2,5-dihydroxybenzoic acid (2,3- and 2,5-DHBA), was significantly lower in Ga/DFO-treated eyes. The mean normalized level of 2,3-DHBA (considered a specific marker of hydroxyl radicals) was 3.5 times higher in untreated eyes. Ga/DFO caused a significant reduction, by 2.56-fold, in lipid peroxidation, as reflected by levels of malondialdehyde. Ascorbic acid, a natural antioxidant present in the retina, is severely depleted in untreated eyes. In contrast, in Ga/DFO-treated eyes, levels were 10 times higher than the control. Energy charge was 2.38 times higher in treated eyes. Levels of purine catabolites (hypoxanthine, xanthine, and uric acid) that reflect excessive metabolism of purine nucleotides were approximately twice higher in untreated retinas. Electroretionographic studies, performed on a different subset of animals, substantiated the biochemical results. In Ga/DFO-treated eyes the amplitude of the mixed cone-rod response b-wave (as compared with fellow nonischemic eyes) fully recovered within 24 h after ischemia (b-wave ratio 1.04 +/- 0.09, [mean +/- SEM]) whereas ischemic/reperfused and nontreated eyes recovered to only 0.33 +/- 0. 05. The results show that severe biochemical and functional retinal injury occurs in cat eyes subjected to ischemia and reperfusion. These severe changes were significantly reduced by a single administration of Ga/DFO just before reperfusion. We hypothesize that the protection afforded by Ga/DFO is due to a combined effect of "Push-Pull" mechanisms interfering with transition metal-dependent and free radical-mediated injurious processes.

Adenine Nucleotides↗
PubMed2003

Cross-section measurements for (n, 2n), (n, p) and (n, n'alpha) reactions on gallium isotopes in the neutron energy range of 13.5-14.6 MeV.

Cross-sections for (n, 2n), (n, p) and (n, n'alpha) reactions have been measured on gallium isotopes at the neutron energies of 13.5-14.6MeV using the activation technique. Data are reported for the following reactions: 69Ga(n, 2n) 68Ga, 69Ga(n, p) 69mZn, 71Ga(n, p) (71m)Zn, and 71Ga(n, n'alpha) 67Cu. The neutron fluences were determined using the monitor reaction 93Nb(n, 2n) 92mNb.

Journal Article↗
PubMed2000

25. Positron Emission Tomography in Hodgkin's Disease. Correlation with Computed Tomography and Gallium 67 Citrate Imaging.

Purpose: To compare the sensitivity of F18 - FDG Positron Emission Tomography (PET), Computed Tomography (CT) and Planar Gallium 67-Citrate (GS) in the diagnosis of Hodgkin's Disease.Materials and Methods: Thirty (30) adult patients with histopathologically confirmed diagnosis of Hodgkin's Disease between Oct 97 and June 98 at KFSH & RC had the three diagnostic imaging modalities for the initial work up; in twenty eight patients for newly diagnosed and in two patients for recurrent disease. Nodular sclerosis was the histological subtype in 25 patients, mixed cellularity in 3 and lymphocytic predominance in 2.Results: For the initial evaluation of the results, a positive site by any of the three diagnostic imaging modalities was considered actual location of the disease. The patient-site sensitivity of PET, CT and for GS were 93.33%, 80% and 53.3% respectively. False negative results were observed in 2 patients with PET, 7 with CT and 14 with GS. The Spleen was the commonest site for false negative result in GS (4 patients) axilla and bones in CT (2 patients each), the 2 patients with false negative results with PET were in the lung. The difference in sensitivity between PET and GS was statistically significant (P = 0.002), but was not significant between PET and CT (P = 0.18). Although CT showed better sensitivity and accuracy when compared with GS, that didn't reach statistical significance (P = 0.09).Conclusion: PET Scan has the highest sensitivity in the initial evaluation in this small group of patients with Hodgkin Disease, especially when compared with GS. Evaluations of the final sensitivity, specificity and accuracy of these imaging modalities will be presented.

Journal Article↗
PubMed1999

Characterization of the Absolute Crystal Polarity across Twin Boundaries in Gallium Phosphide Using Convergent-Beam Electron Diffraction.

: The measurement of absolute crystal polarity is crucial to understanding the structural properties of many planar defects in compound semiconductors. Grain boundaries, including twin boundaries, in the sphalerite lattice are uniquely characterized by the crystallographic misorientation of individual grains and the direction of the crystal polarity in domains adjoining the grain boundary. To evaluate crystal polarity in gallium phosphide (GaP), asymmetrical interference contrast in convergent-beam electron-diffraction (CBED) patterns was used to ascertain the nature and direction of polar bonds. The direction of the asymmetry in the electron diffraction reflections was correlated with the crystal polarity of a sample with known polarity. The CBED technique was applied to determine the polar orientation of grains adjoining Sigma = 3 coherent and lateral twin boundaries in polycrystalline GaP.

Journal Article↗
PubMed2001

Some chemical properties of monochlorogallane: decomposition to gallium(I) trichlorogallate(III), Ga(+)[GaCl3H](-), and other reactions.

Thermal decomposition of monochlorogallane, [H2GaCl]n, at ambient temperatures releases H2 and results in the formation of gallium(I) species, including the new compound Ga[GaHCl3], which has been characterized crystallographically at 100 K (monoclinic P2(1)/n, a = 5.730(1), b = 6.787(1), c = 14.508(1) A, beta = 97.902(5) degrees ) and by its Raman spectrum. The gallane suffers symmetrical cleavage of the Ga(mu-Cl)2Ga bridge in its reaction with NMe3 but unsymmetrical cleavage, giving [H2Ga(NH3)2](+)Cl(-), in its reaction with NH3. Ethene inserts into the Ga-H bonds to form first [Et(H)GaCl]2 and then [Et2GaCl]2.

Journal Article↗
PubMed2002

Transition-metal complexes of a bifunctional tetradentate gallium alkoxide ligand.

The mixed gallium transition-metal complexes [FeCl[Ga(2)((t)Bu)(4)(neol)(2)]] (1) and [M[Ga(2)((t)Bu)(4)(neol)(2)]], M = Co (2), Ni (3), Cu (4), have been prepared by the reaction of [Ga(2)((t)Bu)(4)(neol-H)(2)] (neol-H(2) = 2,2-dimethyl-propane-1,3-diol) with the appropriate metal halide and Proton Sponge. Compounds 1-4 have been characterized by NMR (3), UV/vis, and IR spectroscopy and magnetic susceptibility (solution and solid state), and their molecular structures have been confirmed by X-ray crystallography. The molecular structure of compounds 1-4 consists of a tetracyclic core formed from two four-membered and two six-membered rings. The central metal atom adopts a square pyramidal (1) or square planar (2-4) geometry. The magnetic susceptibilities for 1, 2, and 4 are as expected for strong ligand field environments. On the basis of spectroscopic and structural data, the [Ga(2)((t)Bu)(4)(neol)(2)](2-) ligand appears to be more flexible than other chelating ligands; this is proposed to be due to the flexibility in the O-Ga-O bond angle.

Journal Article↗
PubMed2003

Lanthanum gallium bismuthide, LaGaBi2.

The ternary rare-earth gallium bismuthide LaGaBi(2) has been prepared through reaction of the elements. Its structure (Pearson symbol hP24, hexagonal, space group P6/mmm, Z = 6, a = 13.5483(4) A, c = 4.3937(1) A) contains columns of La(6) trigonal prisms centered by Bi atoms. These columns are surrounded by a framework consisting of three-atom-wide Bi ribbons and Ga(6) rings. Additional Bi atoms are sandwiched between pairs of Ga(6) rings. LaGaBi(2) is structurally closely related to La(13)Ga(8)Sb(21). A retrotheoretical analysis of the structure through extended Hückel band structure calculations suggests an interesting electronic situation in which strong multiple bonding in the Ga-Ga network coexists with weak hypervalent bonding in the Bi-Bi network and confirms the metallic behavior seen in electrical resistivity measurements.

Journal Article↗
PubMed2003

Synthesis and structure of Sr3GaN3 and Sr6GaN5: strontium gallium nitrides with isolated planar [GaN3]6- anions.

Two new strontium gallium nitrides were obtained as single crystals by reaction in molten Na. Black Sr(3)GaN(3) is isostructural with its transition metal analogues, Sr(3)MnN(3), Ba(3)MnN(3), Sr(3)CrN(3), Ba(3)CrN(3), and Ba(3)FeN(3), and is the first example of a 313-ternary nitride containing only main group metals. It crystallizes in space group P6(3)/m (No. 176) with a = 7.584(2) A, c = 5.410(3) A, and Z = 2. Black Sr(6)GaN(5) is isostructural with Ca(6)GaN(5) and also with its transition metal analogues, Ca(6)MnN(5) and Ca(6)FeN(5). It crystallizes in space group P6(3)/mcm (No. 193) with a = 6.6667(6) A, c = 12.9999(17) A, and Z = 2. Both Ga compounds contain isolated planar [GaN(3)](6)(-) nitridometallate anions of D(3)(h)() symmetry.

Journal Article↗