Effect of Er:YAG laser irradiation on acid resistance to bovine dentin in vitro.
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Resin bond strength to Er:YAG laser irradiated dentin has been reported to be lower than that of unlased dentin. The reasons have been much discussed, but not clarified. One hypothetical cause has been discussed that lased dentin is acid resistant, therefore, the etching effect of acid conditions decreases. The purpose of this study was to evaluate the acid resistance of laser-irradiated dentin and compare it with the dissolved mineral of Er:YAG laser irradiated dentin and unlased dentin. This experiment was a pilot study to assess the etching effect of pre-conditioner for resin bonding to lased dentin. Bovine dentin was irradiated by Er:YAG laser and immersed in 0.1 M lactic buffer solution (pH 4.0). The dissolved Ca and P in the solution were then both measured. Dissolved Ca from lased dentin was not significantly different from that coming from unlased dentin (p > 0.05). The molar ratio of Ca/P did not differ significantly between lased and unlased dentin, either (p > 0.05). Under FE-SEM view before immersion, the dentin surface was covered with a smear layer in unlased dentin, but this layer was not clearly observed in lased dentin. These results suggested that the lased dentin had little or no resistance to lactic buffer solution. (+info)
Biokinetics of yttrium-90--labeled huBrE-3 monoclonal antibody.
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BACKGROUND: This study reports summary biokinetics for 17 patients treated with huBrE-3 antibody labeled with indium-111 ((111)In) and yttrium-90 ((90)Y) in a Phase I dose escalation trial. METHODS: Patients were infused with huBrE-3 antibody conjugated to 1-p-isothiocyanatobenzyl 3-methyl- and 1-p-isothiocyanatobenzyl 4-methyl-diethylenetriamine pentaacetic acid (MX-DTPA). The huBrE-3 was labeled with increasing amounts of (90)Y radioactivity according to the following activity regimen: 10 mCi/m(2), 20 mCi/m(2), 33 mCi/m(2), 50 mCi/m(2), and 70 mCi/m(2). In addition to the (90)Y activity, 3--5 mCi of (111)In was labeled to huBrE-3 to serve as an imaging agent. In characterizing the biokinetics of huBrE-3, serial urine and blood samples were acquired. Additionally, whole-body imaging using a scintillation camera was performed at four time points postinfusion. RESULTS: Cumulative urine data yielded a plot of total-body biologic excretion that was relatively flat. Total body regions of interest derived from nuclear medicine scintigrams decreased according to a monoexponential function with a slope slightly greater than the rate of physical decay. When physical decay was combined with the urine biologic excretion rate, the calculated rate of activity decrease was indistinguishable from the scintigraphic rate of decrease in total-body activity. CONCLUSIONS: The authors concluded from these observations that the radioactivity remains essentially inside the patient, that biologic excretion of activity from the total body is not appreciable, and that the path for biologic excretion of activity that does occur is via the urine. The half-time associated with the beta (slow) phase for extraction from the blood averages 40.5 hours. Since large amounts of radioactivity do not appear in the urine, and total-body activity is decreased approximately according to physical decay (64.1 hours), activity must pool elsewhere after leaving the blood. The logical place is the skeleton, with possible selective binding to the bone marrow. Bone marrow biopsies from 4 of 7 patients who consented to serial biopsies were supportive of this conclusion. (+info)
Targeted radiotherapy with [(90)Y]-SMT 487 in mice bearing human nonsmall cell lung tumor xenografts induced to express human somatostatin receptor subtype 2 with an adenoviral vector.
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BACKGROUND: Novel approaches to increasing the therapeutic efficacy of targeted radiotherapy of cancer are required. One strategy to achieve this goal is to induce high-level expression of a receptor on the surface of tumor cells that can be targeted with a radiolabeled peptide. The objectives of this study were to 1) induce somatostatin receptor (SSTr2) expression in tumor cells using an adenovirus encoding the SSTr2 gene (AdSSTr2), 2) demonstrate tumor localization of [(111)In]-DTPA-D-Phe(1)-octreotide in AdSSTr2-injected tumors, and 3) show therapeutic efficacy with [(90)Y]-DOTA-D-Phe(1)-Tyr(3)-octreotide ([(90)Y]-SMT 487). METHODS: SSTr2 expression was validated in vitro by the binding and subsequent internalization of [(111)In]-DTPA-D-Phe(1)-octreotide (21.3% per mg of total protein) in A-427 cells infected with AdSSTr2. In vivo imaging confirmed 5- to 10-fold greater uptake 5.5 hours after intravenous administration of [(111)In]-DTPA-D-Phe(1)-octreotide in AdSSTr2-injected tumors relative to control tumors. For therapy studies, mice bearing established subcutaneous A-427 tumors were given two intratumoral injections of AdSSTr2 1 week apart, followed by an intravenous injection of 400 microCi or 500 microCi [(90)Y]-SMT 487 at 2 and 4 days after each adenoviral administration. Control animals either were not treated or were administered 500 microCi [(90)Y]-SMT 487 with no AdSSTr2 injection. RESULTS: These studies showed that untreated animals and animals treated with no virus and 500 microCi [(90)Y]-SMT 487 had median tumor quadrupling times of 16 and 25 days, respectively. Mice administered AdSSTr2 and either 400 microCi or 500 microCi of [(90)Y]-SMT 487 demonstrated significantly longer median tumor quadrupling times of 40 and 44 days, respectively (P < 0.02). CONCLUSIONS: These studies are the first to demonstrate in vivo therapeutic efficacy using a radiolabeled peptide targeted to a receptor expressed on the surface of tumor cells following gene transfer. Future studies will focus on the optimization of this approach. (+info)
A study of cavity preparation by Er:YAG laser--observation of hard tooth structures by laser scanning microscope and examination of the time necessary to remove caries.
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The purpose of this study was to observe and measure the morphological changes that occur in the hard tissue after the application of Er:YAG laser. Another objective was to evaluate and compare the duration of application of both the laser apparatus and a conventional cutting device. In this study, sound and newly extracted carious tissues were used. The morphological changes in hard tooth structures produced by Er:YAG laser irradiation were examined by using a laser scanning microscope. Results showed that appropriate laser irradiation was 100 mJ/pulse for dentin, and 200 mJ/pulse for enamel. Also, the laser scanning microscope images were less damaged than the SEM images due to pretreatment of the specimens. The time taken to remove carious enamel by laser irradiation was slightly longer than the compared rotary cutting device; however, no differences between the two methods were observed in case of carious dentin removal. (+info)
A study of cavity preparation by Er:YAG laser. Effects on the marginal leakage of composite resin restoration.
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The purpose of this study was to evaluate marginal leakage of composite resin restoration from cavities prepared by Er:YAG laser. The observation of the dentin surface after the application of laser irradiation was performed by LSM, the cutting surface showed a rough surface similar to scales, and exposed dentinal tubules were observed without striations or a smeared layer formation that were observed when using a rotary cutting device. Leakage tests revealed no significant differences in the marginal seal for both enamel and dentin between cavities prepared by Er:YAG laser irradiation and when using an air-turbine. In this study, the usefulness of cavity preparation by Er:YAG laser irradiation in composite resin restoration was suggested. (+info)
ELECTROPHYSIOLOGY OF THE HUMAN HYPOPHYSIS.
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Electrical activity was recorded in the human hypophysis from the neurosecretory fibres of the posterior lobe. In seven patients undergoing trans-sphenoidal hypophysectomy, electrophysiological recording was carried out with a special fine-shielded bipolar concentric electrode with a tip diameter of 30 microns. The rate of unit impulses was modified by anesthetic agents and after intravenous injections of drugs acting at the hypothalamic level.This technique was used to detect the limit between the anterior and posterior lobe in order to perform a selective adeno-hypophysectomy by implantation of yttrium-90 seeds. (+info)
Output energy changes of quartz contact probe for Er:YAG laser with tooth ablation.
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The purpose of this study was to examine the output energy changes of the contact probe for Er:YAG laser with tooth ablation and evaluate the effect of contact surface polishing on output energy. The Er:YAG laser was irradiated to enamel of extracted human incisors for 100 min (5 min x 20 times). The output energy of contact probes was measured every 5 min (n = 3). After 100 min, the contact surfaces were polished using silicon carbide paper up to #1500, and the output energy of the probe was measured. The contact surfaces of the probes were observed and analyzed using an EPMA. After 100 min, the output energy showed 49.4% of the energy of an unused probe. After the contact surfaces were polished to #1500, the output energy returned to 96.4% of baseline. It is suggested that the output energy of the contact probe decreased with tooth ablation, and polishing of the contact surface was effective to regain the energy. (+info)
Nd:YAG laser ablation of enamel for orthodontic use: tensile bond strength and surface modification.
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To test the feasibility of Nd:YAG laser ablation for orthodontic use, bovine enamels were ablated at 2.5 and 3.5 W/pulse conditions. Orthodontic brackets were attached on the ablated enamel surface using a self-curing resin. For comparison, a 37% phosphoric acid solution was used to etch the enamel surface. The strength to detach the brackets was estimated for both surface treatments. Modifications of the enamel surfaces were also compared using a scanning electron microscope for both treatments. The tensile bond strengths from the laser-ablated enamels were significantly lower than that from the phosphoric acid-etched enamels. The higher laser power treatment gave a significantly higher bond strength average than with the lower laser power. The laser-ablated surfaces showed the formation of craters. The formation involved melting and solidification of enamel. Each crater had numerous micropores. Microscopically, the ablated surface was smooth, while much of the acid-etched surface contained numerous microspaces. (+info)