Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “THULIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1993

Mechanism of preconditioning. Ionic alterations.

The mechanism by which preconditioning (brief intermittent periods of ischemia and reflow) improves recovery of function and reduces enzyme release after a subsequent 30-minute period of ischemia was investigated in perfused rat hearts. Specifically, it was hypothesized that ischemia after preconditioning would result in a decreased production of H+ and therefore a smaller rise in [Na+]i and [Ca2+]i via Na(+)-H+ and Na(+)-Ca2+ exchange. To test this hypothesis we measured pHi, [Na+]i, [Ca2+]i, and cell high-energy phosphates during ischemia and reflow, and we correlated this with recovery of contractile function and release of creatine kinase during reflow. 31P nuclear magnetic resonance (NMR) was used to measure pHi and cell phosphates. [Na+]i was measured by 23Na NMR using the shift reagent thulium 1,4,7,10-tetraazacyclododecane-N,N,'N",N"'-tetramethylenephosph onate to distinguish intracellular from extracellular sodium. [Ca2+]i was measured by 19F NMR using hearts loaded with 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid, termed 5F-BAPTA. Basal time-averaged levels of pHi, [Na+]i, and [Ca2+]i were 7.07 +/- 0.08, 9.4 +/- 0.8 mM, and 715 +/- 31 nM, respectively. After 30 minutes of ischemia, in preconditioned hearts, pHi was 6.5 +/- 0.06, [Na+]i was 2.09 +/- 4.4 mM, [Ca2+]i was 2.1 +/- 0.4 microM, and ATP was negligible. In untreated hearts, after 30 minutes of ischemia, pHi was 6.3 +/- 0.08, [Na+]i was 26.7 +/- 3.8 mM, [Ca2+]i was 3.2 +/- 0.6 microM, and ATP was undetectable. During reperfusion after 30 minutes of ischemia, preconditioned hearts had significantly better recovery of contractile function than untreated hearts (71 +/- 9% versus 36 +/- 8% initial left ventricular developed pressure), and after 60 minutes of ischemia, preconditioned hearts had significantly less release of the intracellular enzyme creatine kinase (102 +/- 12 versus 164 +/- 17 IU/g dry wt). We also found that unpreconditioned hearts arrested with 16 mM MgCl2 (to inhibit calcium entry via calcium channels and Na(+)-Ca2+ exchange) before 30 minutes of ischemia recover function on reflow to the same extent as preconditioned hearts with or without magnesium arrest. Thus, preconditioning has no additional benefit in addition to magnesium arrest. In addition, in hearts that received 16 mM MgCl2 just before the 30-minute period of ischemia, preconditioning had no effect on the rise in [Ca2+]i during the 30-minute period of ischemia. These data support the hypothesis that preconditioning attenuates the increase in [Ca2+]i, [Na+]i, and [H+]i during ischemia, most likely because of reduced stimulation of Na(+)-H+ and Na(+)-Ca2+ exchange.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed2004

Facilitation of A[delta]-fiber-mediated acute pain by repetitive transcranial magnetic stimulation.

BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) of the motor cortex modulates acute and chronic pain perception. The authors previously showed that rTMS over the primary motor cortex (M1) inhibited capsaicin-induced acute pain ascending through C-fibers. OBJECTIVE: To investigate the effects of 1-Hz rTMS over M1 on acute experimentally induced pain mediated by Adelta-fibers (i.e., another type of acute pain). METHODS: The authors examined whether rTMS over M1 affected laser evoked potentials (LEPs) in 13 normal subjects using thulium: yttrium-aluminum-garnet laser stimulation. Subjective pain-rating scores and LEPs obtained under three different conditions--rTMS, realistic sham stimulation, and a control condition with no stimulation--were compared. RESULTS: The authors found that 1-Hz rTMS over M1 significantly aggravated the subjective pain and enhanced the N2-P2 amplitudes compared with the sham or control sessions. Because the pain-rating scores and the N2-P2 amplitudes correlated positively, the N2-P2 amplitudes in the present study can be regarded as the cortical correlate of subjective pain. CONCLUSIONS: Together with the authors' previous study on C-fiber pain, this facilitatory effect of repetitive transcranial magnetic stimulation on Adelta-fiber-mediated further strengthens the notion of a relationship between repetitive transcranial magnetic stimulation over M1 and pain perception.

Acute Disease↗
PubMed2004

Mid-infrared laser-induced superheating of water and its quantification by an optical temperature probe.

Free-running thulium laser pulses (Cr:Tm:YAG, lambda = 2.01 microm, tp = 300 micros) were applied to a purified, degassed water sample and the resulting temperature rise was investigated by an optical temperature probe. The probe detected water reflectance index changes with temperature and also the onset of vaporization, which was found to occur in a superheat regime, at approximately 230 degrees C. The experimental data were compared with theoretical temperature calculations, and deviations of less than 20 degrees C were stated. The best agreement between theory and experiment was found for temperatures below 180 degrees C, defining by this the method's high accuracy limit. In conclusion, both the optical temperature probe and the presented calculations can help to improve dosimetry in pulsed IR laser applications by precise temperature measurement and prediction.

Hot Temperature↗
PubMed2005

808-nm diode-pumped continuous-wave Tm:GdVO4 laser at room temperature.

A high-quality gadolinium vanadate (GdVO4) crystal with 7-at. % thulium as the starting material was grown by the Czochralski technique. The measured absorption spectra exhibited sufficient absorption coefficients for laser diodes (LDs) for neodymium laser pumping: 6.0 cm(-1) for pi polarization and 6.2 cm(-1) for sigma polarization at 808 nm. Laser oscillation was carried out with single-stripe 808-nm LDs in an end-pumping configuration. A slope efficiency of 28% and a threshold of 750 mW were exhibited with respect to the absorbed pump power. An output power of 420 mW was achieved at an absorbed power of 2.4 W. It was demonstrated that Tm:GdVO4 is a useful material for 2-microm lasers, particularly in a compact LD-pumped system.

Journal Article↗
PubMed2006

Midinfrared laser source with high power and beam quality.

A simple scheme for generation of high power in the midinfrared is demonstrated. By using a 15 W thulium-doped fiber laser emitting at 1907 nm to pump a Q-switched Ho:YAG laser, we obtained 9.8 W at 2096 nm at a 20 kHz pulse repetition rate with excellent beam quality. The output of this laser was used to pump a doubly resonant zinc germanium phosphide based optical parametric oscillator, and we obtained 5.1 W average power in the 3-5 microm range with M2 approximately = 1.8.

Journal Article↗
PubMed2003

Long-time-storage mechanism for Tm:YAG in a magnetic field.

We obtained a long-time-storage mechanism for spectral features in thulium ions doped into YAG by applying a magnetic field that splits the electronic ground state. We show experimentally that the storage time can be more than 30 s, which is 3 orders of magnitude longer than that of the metastable state that normally is used for information storage in this material. Level splitting and storage lifetimes for various magnetic field strengths of as much as 5 T were investigated. This storage mechanism will be relevant in the many coherent transient-based signal-processing schemes in which Tm:YAG is being used, and we demonstrate long-time storage in a basic data storage application.

Journal Article↗
PubMed2005

Widely tunable 1.94-microm Tm:BaY2F8 laser.

A novel BaY2F8 crystal doped with thulium ions is grown and extensively investigated. Owing to the large number of vibronic levels and to a favorable electron-phonon coupling, extremely wide absorption and emission bands around 1.9 microm are observed. A room-temperature Tm:BaY2F8 laser tunable over a 210-nm interval, from 1849 to 2059 nm, is demonstrated.

Journal Article↗
PubMed2005

Rare earth elements in forest-floor herbs as related to soil conditions and mineral nutrition.

Mixtures of rare earth elements (REEs) in fertilizers are widely used in Chinese agriculture to improve crop nutrition. REE concentrations in wild-growing plants, especially herbs, are little known. This study describes differences in the concentrations and proportions of REEs in eight forest-floor herbaceous plants and relates these differences to soil and mineral nutrient conditions. REEs studied were yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Leaf concentrations of sum REEs differed more than one order of magnitude between species, being highest in Anemone nemorosa (10.1 nmol/g dry mass) and lowest in Convallaria majalis (0.66 nmol/g) from the same site. Leaf concentrations of all REEs correlated positively (p < 0.001), as did sum REE with calcium (Ca) and strontium (Sr) concentrations (p < 0.001). A negative relationship (r = -0.83, (p < 0.001) was measured between phosphorus (P) concentrations and sum REE concentrations in leaves. However, the proportions of the single REEs in the REE sum differed among species. In A. nemorosa, 57% of the molar REE sum was taken by Y + La, and only 21% by Ce. The other extreme was Maianthemum bifolium, with 37% La + Y and 41% Ce. These two species had 2.7-3.0% of the REE sum as heavier lanthanides, compared to 4.1-5.2% in the six other species. No clear relationship between soil properties or REE contents and leaf REE concentrations was detected. For La, however, an overrepresentation in leaves prevailed throughout all species compared to soils, whereas particularly Nd, Sm, and Tb had a lower proportion in the leaves of all species than in their soils. Possible uptake mechanisms of REEs in plants are discussed.

Agriculture↗
PubMed2001

Laser lithotripsy of a urethral calculus via ischial urethrotomy in a steer.

A steer examined because of obstructive urolithiasis and urethral rupture underwent laser lithotripsy, using a chromium-thulium-holmium:yttrium-aluminum-garnet (Ho:YAG) laser inserted through an ischial urethrotomy. Procedures were performed with caudal epidural anesthesia. Six months after surgery, the urethra was patent with no clinical evidence of urethral stricture or fistula. Ischial urethrotomy provided rapid access to the bladder for catheterization and to the obstructive urolith for lithotripsy. Laser lithotripsy was a rapid and effective means of urolith removal in this steer.

Animals↗
PubMed1978

Neutron activation analysis of the rare earth elements in Nasu hot springs.

Eleven rare earth elements (lanthanum, cerium, neodymium, samarium, europium, gadolinium, terbium, holmium, thulium, ytterbium and lutetium) in hot spring waters and sinter deposits in the Nasu area were determined by the neutron activation method. The rare earth elements in hot spring water were pre-concentrated in ferric hydroxide precipitate and neutron-irradiated. The rare earth elements were chemically separated into lighter and heavier groups and the activity of each group was measured with a Ge(Li) detector. Distribution of the rare earth elements between the hot spring water and the sinter deposit was also discussed.

Activation Analysis↗
PubMed2001

Analytical microscopy observations of rat enterocytes after oral administration of soluble salts of lanthanides, actinides and elements of group III-A of the periodic chart.

The behavior in the intestinal barrier of nine elements (three of the group III-A, four lanthanides and two actinides), absorbed as soluble salts, has been studied by two microanalytical methods: electron probe X-ray micro analysis (EPMA) and secondary ion mass spectrometry (SIMS). It has been shown that the three elements of group III-A, aluminium, gallium and indium; and the four lanthanides, lanthanum, cerium, europium and thulium, are selectively concentrated and precipitated as non-soluble form in enterocytes of proximal part of the intestinal tract. SIMS microscopy has shown that these elements are concentrated as a number of submicroscopic precipitates, most of them localized in the apical part of the duodenum enterocytes, where they are observed from one hour to 48 hr after a single intragastric administration. No precipitate is observed after three days. It is suggested that this mechanism of local concentration limits the diffusion of these elements through the digestive barrier, some of them being toxic and none of them having a recognized physiological role. Additionally, the precipitation in duodenal enterocytes, the life time of which is on the order of 2-3 days, allows the elements absorbed as soluble form to be eliminated as a non-soluble form in the digestive lumen along with the desquamation of the apoptotic enterocytes. The intracytoplasmic localization of the precipitates are supposed to be the lysosomes although no direct evidence could be given here due to the very small sizes of the lysosomes of enterocytes. The same results were not observed with the two studied actinides. After administration of thorium, only some very sparse microprecipitates could be observed in intestinal mucosa and, after administration of uranium, no precipitates were observed with the exception of some in the conjunctive part of the duodenal villi.

Actinoid Series Elements↗
PubMed2002

Dissociable neural responses related to pain intensity, stimulus intensity, and stimulus awareness within the anterior cingulate cortex: a parametric single-trial laser functional magnetic resonance imaging study.

Neuroimaging studies have demonstrated activations in the anterior cingulate cortex (ACC) related to the affective component of pain, but not to stimulus intensity. However, it is possible that the low spatial resolution of positron emission tomography, as used in the majority of these studies, obscured areas coding stimulus intensity. We revisited this issue, using a parametric single-trial functional magnetic resonance imaging design, and investigated pain, stimulus intensity, and stimulus awareness (i.e., pain unrelated) responses within the ACC in nine healthy volunteers. Four different stimulus intensities ranging from warm to painful (300-600 mJ) were applied with a thulium yttrium-aluminum granite infrared laser in a randomized order and rated by the subjects on a five point scale (P0-P4). Pain-related regions in the ventral posterior ACC showed a response that did not distinguish between innocuous trials (P0 and P1) but showed a positive linear relationship with the blood oxygenation level-dependent contrast signal for painful trials (P2-P4). Regions in the dorsal anterior ACC along the cingulate sulcus differentiated between P0 (not perceived) and P1 but exhibited no additional signal increase with P2; these regions are related to stimulus awareness and probably to cognitive processing. Most importantly, we identified a region in the dorsal posterior ACC showing a response that discriminated between nonpainful trials (P0 and P1); therefore, this region was simply related to basic sensory processing and not to pain intensity. Stimulus-related activations were all located adjacent to the cingulate motor area, highlighting the strategic link of stimulus processing and response generation in the posterior ACC.

Adult↗
PubMed1992

Holmium laser sclerostomy in glaucoma management: a new tool for an old procedure.

A THC: YAG laser (thulium, holmium, chromium doped YAG crystal) was used to create thermal sclerostomies in 49 glaucomatous eyes of 46 patients. The laser is a long-pulsed (300 microseconds), compact, self contained, solid state laser operating in the near infrared (2.1 mu). A 1 mm conjunctival stab incision was made 12 mm away from the sclerostomy site to allow entry of a specially designed 22-gauge (712 mu) optic probe that delivers energy at a right angle to the long axis of the fiber. Probe insertion produced minimal disturbance of the conjunctiva. Pulse energies of 80 mJ tot 120 mJ were used with a repetition rate of 5 pulses/sec. Total energy levels to produce full-thickness sclerostomies ranged from 1.4 to 7.2 J. Subconjunctival 5-fluorouracil injections were administered in 46 eyes. Estimated probability of success was 74% at 6 months and 67% at 12 months. Mean intraocular pressure of successful cases was 13.3 mmHg at both both 6 months & 12 months. Twelve cases failed within the initial 6 months, and two additional cases failed by 12 months.

Follow-Up Studies↗
PubMed1992

Determination of an appropriate laser setting for THC-YAG laser sclerostomy ab externo in rabbits.

To determine an appropriate setting for the THC-YAG laser (chromium-sensitized, thulium, and holmiumdoped YAG laser), we performed sclerostomy ab externo on 24 pigmented rabbits. The laser energy was delivered via a subconjunctivally-inserted fiberoptic probe that was placed at the limbus through a small conjunctival incision. We used four pulse-energy levels to perform the sclerostomies: 80 mJ, 120 mJ, 160 mJ, and 200 mJ. At all these levels, a new outflow pathway was easily created, a filtering bleb was formed, and intraocular pressure (IOP) was immediately reduced. Severe tissue damage around the sclerostomy site occurred with the 160-millijoule and 200-millijoule pulses. The 80-millijoule pulse created a relatively small patent sclerostomy, providing only relatively brief IOP reduction. We conclude that 120-millijoule is the most appropriate laser-pulse energy for use in pigmented rabbits.

Animals↗
PubMed1992

Transcanalicular THC:YAG dacryocystorhinostomy.

Chromium-sensitized and thulium- and holmium-doped YAG lasers (THC:YAG laser) were used to create a nasal bony ostium in the area of the lacrimal sac fossa in four fresh frozen bisected human cadaver heads. The lasers-long pulsed (300 milliseconds), compact, self-contained, and solid state--operate in the near infrared (2.1 microns). The opening was created by passing the 320-micrometer laser fiber across the canalicular system. Pulse energies of 250 to 900 mJ were used with a repetition rate of 5 to 15 pulses per second. Energy levels ranging from 1.25 to 9 W produced a full-thickness bony ostium approximately 3 to 4 mm in diameter. Silicone tubing was then threaded through the superior and inferior canaliculus system in the standard fashion. This technique may simplify conventional dacryocystorhinostomy as well as endonasal laser dacryocystorhinostomy procedures.

Dacryocystorhinostomy↗
PubMed2005

Selective mineral elements concentration of the intestinal mucosa role of the lysosomes of duodenal enterocytes in the handling of mineral elements after intragastric administration.

Intragastric administration to rats of four soluble lanthanides cerium, lanthanum, europium, thulium and of three soluble elements of group IIIA aluminium, indium and gallium has been shown in previous studies. In this work two new rare earths gadolinium and terbium were studied using the same protocols and the same methods (transmission electron microscopy and ion microanalysis). among the previously studied elements, some of them were administered simultaneously on the one hand aluminium and indium, and on the other hand, lanthanum and cerium. These metals were looked for in intestinal mucosa, liver and kidney. The results showed: a) gadolinium and terbium were selectively concentrated in lysosomes of duodenal enterocytes, precipitated as non-soluble phosphate salts and eliminated with the cell's turn-over in less than 48 hr; b) Administered simultaneously, they precipitated in the same lysosome. c/ none of them was observed in the liver or kidney even with high dose. This study brings up to nine the number of elements forming a non-soluble phosphate salts, explaining their precipitation in lysosomes. None of them have a physiological role, two are toxic (aluminium and indium). This rapid intralysosomal concentration is an efficient mechanism which limits the diffusion of the foreign substances through the digestive barrier, then permits their elimination along with the cytoptose phenomenon in the intestinal lumen.

Animals↗
PubMed1991

In vivo comparison of THC:YAG laser welding to sutured closure of biliary tissue.

Percutaneous endoscopic approaches to cholelithiasis are an alternative to extracorporeal shockwave lithotripsy which offer advantages of fewer restrictions on stone size and type as well as avoidance of fragmented stone passage complications. Endoscopic techniques would be facilitated by methods of welding gallbladder tissues. The technical constraints imposed by the endoscopic approach favor nonsuture methods of fusing gallbladder tissues. To evaluate a laser method for fusing biliary tissue, we have compared the healing response of laser-welded versus polyglycolic acid suture-closed incisions in canine gallbladder tissue in vivo. The laser used was a thulium-holmium-chromium:YAG laser producing 200-microsecond, 300-millijoule pulses at 2.15 microns. Serial sacrifice of dogs that underwent laser or suture closure of incisions made in the fundus of the gallbladder revealed that all repairs healed without evidence of leakage or infection. Laser-welded cholecystotomy sites had complete fibrous healing of the wound by two weeks postoperatively and reepithelialization by three weeks after operation. Suture-closed wounds were still without complete epithelization four weeks after the procedure. Laser welding may be a useful technique in endoscopic biliary surgery.

Animals↗
PubMed1991

Dynamic sodium chemical shift imaging for the study of aqueous humor flow.

Ocular images were obtained using sodium chemical shift imaging (CSI) and 1,4,7,10-tetraazacyclododecane-N,N'N",N"'-tetramethylenephospho nate thulium (III) [Tm(DOTP)5-], a paramagnetic chemical shift reagent. After injecting the shift reagent into the anterior chamber of rabbits, serial imaging was done, monitoring the change in chemical shift with time. Sodium CSI produced images of the eye in three dimensions, quantitatively depicting the spatial and temporal changes in the concentration of a paramagnetic tracer substance. The Tm(DOTP)5- is eliminated from the anterior chamber by first-order kinetics with a half-life of 49 min. These data suggest that this substance is eliminated from the anterior chamber at the same rate as aqueous humor is replaced. Sodium CSI shows promise as a valuable technique for monitoring fluid dynamics in the living eye.

Animals↗