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PubMed1995

Effect of lanthanides on the relaxation rates of 89Y and 29Si in yttrium silicon oxynitride phases.

Additions of paramagnetic lanthanides are found to increase the relaxation rates of both 89Y and 29Si in the yttrium silicon oxynitride compounds Y2Si3N4O3 (N-melilite) and Y4Si2O7N2 (J-phase), allowing the observation of previously unreported 89Y magic-angle spinning nuclear magnetic resonance spectra of these phases. The dependence of the 89Y and 29Si relaxation rates was determined as a function of Yb3+ and Gd3+ concentration. Both the 29Si and 89Y resonances become broader with increasing Yb concentration, but at all lanthanide concentrations the 89Y spectrum of J-phase is broader than that of N-melilite, possibly due to a greater distribution of Y site geometries in the former. At concentrations below about 360 mumol g-1, the lanthanide ions appear to be incorporated in the lattice, but are not involved in covalent bonding to Y or Si. The effect of a series of lanthanides on the 89Y and 29Si relaxation rates and line widths is presented in terms of the lanthanide spin quantum numbers and magnetic moments. The most effective lanthanide was found to be Eu3+, giving fast relaxation (particularly for 89Y) and sharp lines.

Air Pollutants, Occupational↗
PubMed1993

Radioassays of yttrium-90 used in nuclear medicine.

Yttrium-90 radioassays are required in nuclear medicine at the gigabecquerel activity level (GBq) for measuring injected activity, and at the becquerel level for measuring individual tissue samples in biodistribution studies. A method of standardizing 90Y for activity using high-efficiency liquid-scintillation counting is described. Solution standards were used to establish the calibration factors for commercial radionuclide calibrators. Detection efficiencies are also presented for liquid-scintillation counting, NaI(T1) bremsstrahlung counting and Cerenkov counting.

Nuclear Medicine↗
PubMed2006

Cerium and yttrium oxide nanoparticles are neuroprotective.

The responses of cells exposed to nanoparticles have been studied with regard to toxicity, but very little attention has been paid to the possibility that some types of particles can protect cells from various forms of lethal stress. It is shown here that nanoparticles composed of cerium oxide or yttrium oxide protect nerve cells from oxidative stress and that the neuroprotection is independent of particle size. The ceria and yttria nanoparticles act as direct antioxidants to limit the amount of reactive oxygen species required to kill the cells. It follows that this group of nanoparticles could be used to modulate oxidative stress in biological systems.

Aluminum Oxide↗
PubMed2005

Increased osteoblast functions on undoped and yttrium-doped nanocrystalline hydroxyapatite coatings on titanium.

In order to improve orthopedic implant performance, the objective of this in vitro study was to synthesize nanocrystalline hydroxyapatite (HA) powders to coat titanium. HA was synthesized through a wet chemical process. The precipitated powders were either sintered at 1100 degrees C for 1h in order to produce UltraCap HA (or microcrystalline size HA) or were treated hydrothermally at 200 degrees C for 20 h to produce nanocrystalline HA. Some of the UltraCap and nanocrystalline HA powders were doped with yttrium (Y) since previous studies demonstrated that Y-doped HA in bulk improved osteoblast (or bone-forming cell) function over undoped HA. The original HA particles were characterized using X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), BET, a laser particle size analyzer, and scanning electron microscopy (SEM). These powders were then deposited onto titanium by a novel room-temperature process, called IonTite. The properties of the resulting HA-coatings on titanium were compared to respective properties of the original HA powders. The results showed that the chemical and physical properties of the original HA powders were retained when coated on titanium by IonTite, as determined by XRD, SEM, and atomic force microscopy (AFM) analysis. More importantly, results showed increased osteoblast adhesion on the nanocrystalline HA IonTite coatings compared to traditionally used plasma-sprayed HA coatings. Results also demonstrated greater amounts of calcium deposition by osteoblasts cultured on Y-doped nanocrystalline HA coatings compared to either UltraCap IonTite coatings or plasma-sprayed HA coatings. These results encourage further studies on nanocrystalline IonTite HA coatings on titanium for improved orthopedic applications.

Biocompatible Materials↗
PubMed2004

Fracture resistance of yttrium oxide partially-stabilized zirconia all-ceramic bridges after veneering and mechanical fatigue testing.

OBJECTIVES: Yttria-stabilized zirconia (Y-TZP) ceramic is a high-performance material with excellent mechanical properties suitable for fixed partial dentures. The purpose of this study was to evaluate after fatigue testing, the effect of heat-treatment and veneering on the fracture resistance of frameworks manufactured using sintered and subsequently hot isostatic pressed yttrium oxide partially-stabilized zirconia (Denzir). METHODS: The specimens were subjected to dynamic loading in water. Thereafter, using a universal testing machine, the fracture resistance of three-unit fixed partial dentures was determined; (i) of the frameworks as delivered after machining, (ii) after the frameworks had been subjected to heat-treatment similar to veneering with a glass-ceramic (Eris) or a feldspar-based ceramic (Vita D) and (iii) after the frameworks had been veneered with these ceramics. In addition, the fracture resistance of frameworks as delivered after machining not subjected to dynamic loading in water was determined. RESULTS: Cyclic loading in water did not significantly (p>0.05) affect the fracture resistance. The load necessary to fracture the frameworks as delivered after machining was significantly (p<0.001) higher than for the heat-treated and veneered specimens. No significant difference was seen between the specimens veneered with Eris and those veneered with Vita D (p>0.05). For all but three specimens the fractures were located in the loading point and through one of the connectors. SIGNIFICANCE: Heat-treatment and veneering reduce fracture resistance of hot isostatic pressed zirconia. Nevertheless, the results obtained indicate that it is an interesting material for potential in all-ceramic restorations.

Ceramics↗
PubMed2005

The fluorescence characteristic of the yttrium-norfloxacin system and its analytical application.

In this paper, a simple, rapid and sensitive spectrofluorimetric method based on the formation of yttrium complexes has been developed for the determination of norfloxacin (NFLX). The affecting factors of the enhancement were studied in detail. Under optimum conditions, a linear relationship was obtained between the enhanced fluorescence intensity and the NFLX concentration in the range 1.0 x 10(-9) to 1.0 x 10(-5)mol/l and the detection limit of NFLX was 3.8 x 10(-11)mol/l (S/N=3). The method is applied for the determination of NFLX in actual sample (norfloxcain eye drops), the average recovery is 102.4% (n=5), and the result obtained is satisfactory.

Buffers↗
PubMed2006

Fluorescence enhancement of yttrium(III)-rutin by nucleic acids in the presence of cetyltrimethylammonium bromide.

It is found that nucleic acids can enhance the fluorescence intensity of yttrium(III) (Y(3+))-rutin in presence of cetyltrimethylammonium bromide (CTMAB) system. In hexamethylenetetramine (HMTA)-HCl buffer, the maximum enhanced fluorescence is produced, with maximum excitation and emission wavelengths at 452 and 520 nm, respectively. Based on this, a new fluorimetric method of determination of nucleic acids is proposed. Under optimum conditions, the enhanced fluorescence intensity is proportion to the concentration of nucleic acids in the range of 1.0 x 10(-7) to 1.0 x 10(-5)g/ml for fish sperm DNA (fsDNA), 1.0 x 10(-7) to 4.6 x 10(-6)g/ml for yeast RNA (yRNA), their detection limits (S/N=3) are 7.5 x 10(-8), 8.0 x 10(-8)g/ml, respectively. The interaction mechanism is also studied.

Animals↗
PubMed2006

Yttrium-90 internal radiation therapy for hepatic malignancy.

Surgical resection is the only potentially curative strategy in the treatment of patients with hepatic malignancy. Unfortunately, due to advanced stage, underlying liver disease, or medical comorbidities, most patients are inoperable at the time of presentation. As a result, various locoregional therapies have emerged for otherwise unresectable hepatic tumors. One such modality is Yttrium-90 (Y(90)) internal radiation therapy. Numerous studies demonstrate the safety and potential survival benefit of intra-arterial Y(90) for primary and metastatic liver tumors. However, more data is needed in order to understand the exact role of Y(90) in the algorithm of hepatic tumor management. This review presents the available literature on Y(90) with the aim of defining the current status of Y(90) in the armamentarium of therapeutic strategies for hepatic malignancy.

Antineoplastic Agents↗
PubMed2004

Synchronous evaluation of toxico- and pharmaco-dynamics of yttrium-90 by a novel autoradiographic procedure.

A synchronous evaluation was performed, using a quick in vivo [2-(14)C]thymidine labeling method, of the toxico- and pharmaco-dynamics of a given dose of yttrium-90 (90Y) at a given time after injection to nude BALB/c mice loaded with 10(7) HuO9 cells. Quantitative data were 14C-microautoradiographs of the liver lobule, intestinal crypts, epiphysial growth plate, secondary ossification center containing pluripotent stem cells, perifollicular zone containing unipotent stem cells in the spleen, and plasmacytoma cells in the osteogenic sarcoma in each mouse following a 10-min labeling with 14C at 0.5, 6, and 24 h after i.v. injection of 90Y. Results show that the cell proliferation rate of the stem cells in respective tissues was markedly suppressed, dependent on time after dosing and the dose of 90Y; 3.7, 37, 370, 3700, and 37,000 kBq per mouse (25 g). In addition to the above, the sensitivity of the proliferation rate was dependent on amitosis or mitosis and the AUC value of 90Y-concentration at specific locations of the cells in the mouse body. The most sensitive cells were the plasmacytoma cells, followed by the pluripotent and unipotent stem cells, the intestinal crypts, epiphysial growth plate, and liver cells.

Animals↗
PubMed1997

Effects of Nd: and Ho:yttrium-aluminium-garnet lasers on human dentine fluid flow and dental pulp-chamber temperature in vitro.

Dentine specimens were prepared from freshly extracted third molars and initial permeability measured. Each specimen was subjected to Nd:yttrium-aluminium-garnet (YAG) (1.06 or 1.32 microns wavelength) or Ho:YAG (2.10 microns wavelength) laser energy while temperatures in the pulp chambers were recorded. Permeability was again measured and the surfaces examined by scanning electron microscopy. Six crown segments were used for each laser variable and eight permeability measurements were taken before and eight after laser exposure, while temperature was recorded during treatment. All wavelengths reduced permeability but temperature rises were high enough to have caused pulpal damage, indicating that shorter treatment times and lower power settings may be necessary if used in vivo.

Aluminum Silicates↗
PubMed1981

Effect of intra-articular yttrium-90 on chronic pyrophosphate arthropathy of the knee.

Fifteen patients with bilateral, symmetrical, chronic pyrophosphate arthropathy of the knee were given intra-articular injections of yttrium-90 (5 mCi) plus steroid (triamcinolone hexacetonide, 20 mg) into one knee, and saline plus steroid into the other (control) knee. Allocation of the 90Y injection was random and double blind. After 6 months there was significantly less pain, inactivity stiffness, joint-line tenderness, and effusion in the 90Y-injected knees than in the controls (p less than 0.01). There were also significant differences between 90Y-injected and control knees in the changes in range of movement (p less than 0.01) and joint circumference (p less than 0.05) caused partly by progression of disease in the control knees. No significant differences in joint deformity, instability, X-ray appearance, or synovial-fluid analysis were seen. In all cases patient and observer assessment favoured the treated side (p less than 0.01). These findings indicate that intra-articular 90Y may be of benefit in chronic pyrophosphate arthropathy, a disease for which there is no treatment. The predilection of this condition to affect the knees of the elderly makes such treatment highly suitable because the joint lends itself readily to injection and the procedure carries very few actual or potential risks in this age group.

Aged↗
PubMed2001

A new cause of renal thrombotic microangiopathy: yttrium 90-DOTATOC internal radiotherapy.

The chelator somatostatin analogue dota-D-phe(1)-tyr(3)-octreotide (DOTATOC), which is stably labeled with the beta-emitting radioisotope yttrium 90 ((90)Y), is used as internal radiotherapy for the treatment of patients with advanced neuroendocrine tumors. We report 5 patients who developed chronic renal failure, caused in 3 patients by biopsy-proven thrombotic microangiopathy (TMA). Twenty-nine patients (14 men, 15 women) with normal renal function before therapy were treated with divided intravenous doses of (90)Y-DOTATOC approximately 6 weeks apart (mean normalized cumulative dose, 165.4 +/- 36.4 mCi/m(2)). Twenty-two of 29 patients were administered a normalized cumulative dose of 200 mCi/m(2) without side effects. Among the 7 patients (6 women, 1 man) administered a normalized cumulative dose greater than 200 mCi/m(2), 5 patients (4 women, 1 man) developed renal failure. Increasing serum creatinine levels were observed within 3 months after the last (90)Y-DOTATOC injection. The evolution was rapidly progressive in 3 patients, resulting in end-stage renal failure within 6 months. The remaining 2 patients developed chronic renal insufficiency (mean serum creatinine level, 300 micromol/L an average 16 months after the end of treatment). Renal biopsies performed in 3 patients showed typical signs of TMA involving glomeruli, arterioles, and small arteries. Patients treated with high-dose (90)Y-DOTATOC internal radiotherapy (cumulative dose > 200 mCi/m(2)) are at high risk to develop severe renal failure caused by TMA lesions. The histopathologic lesions are identical to those found after external radiotherapy, which suggests a causal relationship between (90)Y-DOTATOC and renal TMA.

Biopsy↗
PubMed1978

Investigation of cerium and yttrium ions effects on microbial nitrogen fixation and determination of inhibition.

Critical investigation of the effect of yttrium and cerium ions in culture media for nitrogen-fixing bacteria showed strong inhibition. There was a decrease in the amount of nitrogen fixed; simultaneously, in the samples containing cerium ions, carbon consumption values increased as the molarity of metal ion was enhanced. Inhibition rate was invariably maximum at the highest concentration of metal ions.

Bacteria↗
PubMed1997

Preparation of yttrium-90-labeled human macroaggregated albumin for regional radiotherapy.

Human macroaggregated albumin (MAA), which is currently labeled with technetium-99m (99mTc) and 99mTc-MAA, is used clinically as a pulmonary perfusion agent and was directly labeled with yttrium-90 (90Y)-acetate. This study evaluated whether 90Y-MAA could be potential radiotherapeutic agent for regional radiotherapy against malignant tumors. MAA suspended in 0.1 M sodium acetate buffer, pH 5.8, was incubated with 90Y-acetate and purified in order to get rid of unstable binding of 90Y by electrophoresis. The radiochemical purity of 90Y-MAA in normal human serum was estimated by an agarose electrophoresis method and was more than 94% over 168 h in vitro. Following the intratumoral administration of 90Y-MAA, the time course of tumor radioactivity and the biodistribution in nude mice bearing human neuroblastoma were investigated up to 168 h. More than 93% of the radioactivity of the injected dose was found on the subcutaneous tumor over 168 h. The bone radioactivity was shown as 0.06 +/- 0.03% injection dose/gram tissue (% ID/g) (n = 5) at 24 h, 0.73 +/- 0.20% ID/g at 72 h, 0.92 +/- 0.16% ID/g at 120 h, and 2.51 +/- 0.59% ID/g at 168 h. A slight increase in radioactivity was noted in the liver, kidneys, and spleen over the 168-h periods. In conclusion, 90Y-MAA may be a potential agent for regional radiotherapy (brachytherapy) because of the sufficient persistence in the tumor following an intratumoral administration.

Albumins↗
PubMed1999

Labeling of phosphorothioate antisense oligonucleotides with yttrium-90.

Novel yttrium-90 (90Y)-labeled phosphorothioate antisense oligonucleotides were designed as a potential targeted radionuclide therapeutic agent for malignant tumors. A 15-mer phosphorothioate antisense oligonucleotide, which was complementary to the translation start region of the N-myc oncogene mRNA, was conjugated with isothiocyanobenzyl ethylenediamine tetraacetic acid (SCN-Bn-EDTA), via a C-5-substituted deoxyuridine that had replaced a thymine in the oligonucleotide, and was then labeled with 90Y-acetate. Following purification, the radiochemical purity of the 90-Y-Bn-EDTA-phosphorothioate antisense oligonucleotides was estimated by 2.0% agarose gel electrophoresis, and the specific hybridization of 90Y-Bn-EDTA-phosphorothioate antisense oligonucleotide to a phosphorodiester sense oligonucleotide was investigated by 20% polyacrylamide gel electrophoresis in a cell-free system. Radiochemical purity was 98.7 +/- 0.4% at 72 h after labeling and 90.3 +/- 0.9% after 72-h incubation with human normal serum. The 90Y-Bn-EDTA-phosphorothioate antisense oligonucleotide hybridized specifically to a complementary phosphorodiester sense oligonucleotide. In conclusion, phosphorothioate antisense oligonucleotides can be labeled stably with 90Y using SCN-Bn-EDTA without loss of hybridization properties.

Blood Physiological Phenomena↗
PubMed1999

Yttrium-90-labeled human macroaggregated albumin for internal radiotherapy: combined use with DTPA.

The aim of this study was to investigate the possibility of yttrium-90-labeled human macroaggregated albumin (90Y-MAA) as an internal radiotherapeutic agent for whole-lung irradiation in combination with diethylenetriamine pentaacetic acid (DTPA). The influence of trisodium calcium DTPA (CaNa3DTPA) on the radioactivity of 90Y-MAA in serum was investigated in vitro. The effect of CaNa3DTPA on the biodistribution of radioactivity in normal mice intraveneously injected with 90Y-MAA was examined. CaNa3DTPA could deprive in vitro radioactivity of 90Y-MAA in 48-h incubation. Most of the radioactivity (>90% injected dose per lung) was observed at murine lung after injection of 90Y-MAA. Pulmonary radioactivity was cleared within 72 h postinjection, whereas the radioactivities in the bone, liver, kidneys, and spleen increased with a peak at 48 h. CaNa3DTPA-treatment reduced the in vivo radioactivities in bone, liver, and kidneys without influence on the radioactivity of lung. In conclusion, combined use of CaNa3DTPA enables 90Y-MAA to be used as a radiopharmaceutical for internal irradiation against whole lung.

Albumins↗