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At least 973 records · Page 54Linked to original sources
PubMed2003

Identification of proteins separated by one-dimensional sodium dodecyl sulfate/polyacrylamide gel electrophoresis with matrix-assisted laser desorption/ionization ion trap mass spectrometry; comparison with matrix-assisted laser desorption/ionization time-of-flight mass fingerprinting.

Digests from ten gel bands containing low abundance proteins were analyzed by both matrix-assisted laser desorption/ionization ion trap (MALDI-IT) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) methods. MALDI-TOF techniques were able to identify only one protein from all 10 gel bands, while MALDI-IT identified eight proteins from the same 10 bands. The ability to perform MS/MS experiments with a MALDI-IT instrument leads to protein identifications based on both peptide molecular mass and sequence information, and is much less prone to errors and uncertainties introduced by peptide fingerprinting methodologies in which protein identification is based on peptide molecular masses alone.

Amino Acid Sequence↗
PubMed1991

A matrix-assisted laser desorption time-of-flight mass spectrometer based on a 600 ps, 1.2 mJ nitrogen laser.

The design and performance of a short-pulse UV laser desorption time-of-flight mass spectrometer is described. The instrument combines the advantages of a 600 ps, 337 nm pulsed nitrogen laser with a compact, high-voltage extraction linear time-of-flight analyzer. A number of peptides and proteins have been analyzed to demonstrate sensitivity, high mass range, resolution and mixture analysis.

Amino Acid Sequence↗
PubMed2005

Potential of laser ablation and laser desorption mass spectrometry to characterize organic and inorganic environmental pollutants on dust particles.

Stainless steel factories are known to release particles into the atmosphere. Such particulate matter contains significant amounts of heavy metals or toxic inorganic compounds and organic pollutants such as, for example, Cr(VI) and polycyclic aromatic hydrocarbons (PAHs). The investigation of Cr(VI) and PAHs is often complicated by the associated matrix. Organic and inorganic pollutants present in stainless steel dust particles have been investigated with the same laser microprobe mass spectrometer according to two original methodologies. These analytical methods do not require time-consuming pretreatment (extraction, solubilization) or preconcentration steps. More specifically, experiments are conducted with a Fourier transform ion cyclotron resonance mass spectrometer coupled to an ArF (193 nm) or a tripled frequency Nd-YAG (355 nm) laser. Experiments at 355 nm allow the nature of the most frequently occurring Cr(III)/Cr(VI) compounds in dust particles to be identified. Examination of PAHs at 193 nm is assisted by the formation of pi-complexes with 7,7',8,8'-tetracyanoquinodimethane to prevent their evaporation in the mass spectrometer during analysis and to ensure an increase in sensitivity.

Air Pollutants, Occupational↗
PubMed2002

Identification of acetylation and methylation sites of histone H3 from chicken erythrocytes by high-accuracy matrix-assisted laser desorption ionization-time-of-flight, matrix-assisted laser desorption ionization-postsource decay, and nanoelectrospray ionization tandem mass spectrometry.

A new strategy has been employed for the identification of the covalent modification sites (mainly acetylation and methylation) of histone H3 from chicken erythrocytes using low enzyme/substrate ratios and short digestion times (trypsin used as the protease) with analysis by HPLC separation, matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF), matrix-assisted laser desorption ionization-postsource decay, and tandem mass spectrometric techniques. High-accuracy MALDI-TOF mass measurements with representative immonium ions (126 for acetylated lysine, 98 for monomethylated lysine, and 84 for di-, tri-, and unmethylated lysine) have been effectively used for differentiating methylated peptides from acetylated peptides. Our results demonstrate that lysines 4, 9, 14, 27, and 36 of the N-terminal of H3 are methylated, while lysines 14, 18, and 23 are acetylated. Surprisingly, a non-N-terminal residue, lysine 79, in the loop region hooking up to the bound DNA, was newly found to be methylated (un-, mono-, and dimethylated isoforms coexist). The reported mass spectrometric method has the advantages of speed, directness, sensitivity, and ease over protein sequencing and Western-blotting methods and holds the promise of an improved method for determining the status of histone modifications in the field of chromosome research.

Acetylation↗
PubMed2003

[Laser in situ keratomileusis for correction of hyperopia and hyperopic astigmatism using a scanning spot excimer laser. Results of a prospective clinical study after 1 year].

PURPOSE: The purpose of this investigation was to evaluate the safety, efficacy, predictability, stability and complications of LASIK for the treatment of hyperopia and hyperopic astigmatism using a scanning spot excimer laser. PATIENTS AND METHODS: A total of 64 consecutive LASIK operations (37 patients, mean age 41 years, range 22-68 years) have been evaluated. The Hansatome microkeratome producing a superior hinge (flap diameter 9.5 mm) and a scanning spot excimer laser with an optical zone of 6.0 mm were used. Examinations were performed preoperatively, after 1 day, 7 days, 1 month, 4 and 12 months. RESULTS: One year after the primary procedure only 1 eye lost 2 or more lines of best-corrected visual acuity, 91% were within +/-1 line and 4 eyes gained 2 lines. Of these eyes 50 (86%) reached an uncorrected visual acuity of > or=0.5, 32 (55%) > or=0.8, 16 (28%) > or=1.0, 24 eyes (41%) needed a refractive correction of +/-0.5 D, 44 eyes (76%) of +/-1.0 D and 55 eyes (95%) of +/-2.0 D. The mean spherical equivalent after 1 year was +0.17+/-0.85 D. CONCLUSIONS: LASIK is suitable for the correction of hyperopia (up to a maximum of +5 D) and for hyperopic astigmatism (up to a maximum of -5 D). However, results were better in lower hyperopia (up to +3 D) than in the moderate hyperopia. The refractive results showed overall a good stability during the 12-month study period, but higher regression occurred in a few cases.

Adult↗
PubMed2005

Comparison of confocal scanning laser ophthalmoscopy, scanning laser polarimetry and optical coherence tomography to discriminate ocular hypertension and glaucoma at an early stage.

BACKGROUND: The aim was to compare the ability of confocal scanning laser ophthalmoscopy (CSLO), scanning laser polarimetry (SLP), and optical coherence tomography (OCT) to discriminate eyes with ocular hypertension (OHT), glaucoma-suspect eyes (GS) or early glaucomatous eyes (EG) from normal eyes. METHODS: Ocular hypertension, GS, and EG were defined as normal disc with intraocular pressure >21 mmHg, glaucomatous disc without visual field loss, and glaucomatous disc accompanying the early glaucomatous visual filed loss respectively. Ninety-three normal eyes, 26 OHT, 55 GS, and 67 EG were enrolled. Optic disc configuration was analyzed by CSLO (version 3.04), whereas retinal nerve fiber layer thickness was analyzed by SLP (GDx-VCC; version 5.3.2) and OCT-1 (version A6X1) in each individual. The measurements were compared in the four groups of patients. Receiver operating characteristic curve (ROC) and area under the curve (AUC) discriminating OHT, GS or EG from normal eyes were compared for the three instruments. RESULTS: Most parameters in GS and EG eyes showed significant differences compared with normal eyes. However, there were few significant differences between normal and OHT eyes. No significant differences were observed in AUCs between SLP and OCT. In EG eyes, the greatest AUC parameter in OCT (inferior--120; 0.932) had a higher AUC than that in CSLO (vertical cup/disc ratio; 0.845; P=0.017). In GS, the greatest AUC parameter in OCT (average retinal nerve fiber layer [RNFL] thickness; 0.869; P=0.002) and SLP (nerve fiber indicator [NFI]; 0.875; P=0.002) had higher AUC than that in CSLO (vertical cup/disc ratio; 0.720). CONCLUSIONS: Three instruments were useful in identifying GS and EG eyes. For glaucomatous eyes with or without early visual field defects, SLP and OCT performed similarly or had better discriminating abilities compared with CSLO.

Area Under Curve↗
PubMed1994

Predictors of outcome of percutaneous excimer laser coronary angioplasty of saphenous vein bypass graft lesions. The Percutaneous Excimer Laser Coronary Angioplasty Registry.

A total of 495 patients underwent treatment with excimer laser angioplasty for 545 saphenous vein graft stenoses. Clinical success was achieved in 455 of 495 patients (92%), as indicated by < or = 50% residual stenosis at every target lesion and no complication during hospitalization. At least 1 in-hospital complication occurred in 30 of 495 patients (6.1%): death (1.0%), bypass surgery (0.6%), and Q-wave (2.4%) or non-Q-wave (2.2%) myocardial infarction. Relative risk analysis showed that ostial lesions (n = 65) tended to have higher clinical success (success rate = 95%, adjusted odds ratio [OR] = 2.1 [95% confidence interval (CI) 0.62, 6.88]; p = 0.24) and lower complications (complication rate = 0%, OR = 0.10 [CI 0.01, 0.79]; p = 0.03) than lesions in the body of the vein graft. Lesions > 10 mm (n = 131) had lower success (success rate = 84%, OR = 0.30 [CI 0.16, 0.56]; p = 0.001) and higher complications (complication rate = 12%, OR = 3.3 [CI 1.6, 6.6]; p = 0.004) than discrete lesions. Lesions in small vein grafts < 3.0 mm (n = 76) tended to have increased success (success rate = 94%, OR = 1.55 [CI 0.70, 3.44]; p = 0.39) and lower complications (complication rate = 2.2%, OR = 0.31 [CI 0.10, 0.94]; p = 0.03). Thus, excimer laser-facilitated angioplasty has the most favorable outcome for discrete lesions located at the ostium of all grafts and in the body of smaller saphenous vein grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Mechanical properties of laser welds of titanium in dentistry by pulsed Nd:YAG laser apparatus.

The use of titanium in dentistry is increasing, and an adequate method of joining titanium units of restorations is needed. This study examined the welding of titanium with a normal pulse Nd:YAG laser. Laser welding of titanium was effective when performed in an argon atmosphere. ANOVA for the three-point bending test showed a correlation between the bending strength of a weld, the atmosphere under which the irradiation is performed, and the intensity of the irradiation.

Analysis of Variance↗
PubMed1991

The Glaucoma Laser Trial (GLT): 3. Design and methods. Glaucoma Laser Trial Research Group.

The Glaucoma Laser Trial (GLT) was an investigator-initiated, grant-supported, multicenter, randomized, controlled clinical trial designed to investigate the efficacy and safety of argon laser trabeculoplasty (ALT) as an alternative to medical treatment for newly diagnosed primary open-angle glaucoma (POAG). One eye of each patient was randomly assigned to ALT followed by medical treatment if needed to control intraocular pressure (IOP). The patient's other eye was assigned to medical treatment. Medical treatment for either eye was prescribed according to a stepped sequence. Patients were followed for a minimum of 2 years. Monitoring for control of IOP and for adherence to the protocol continued throughout the followup period. This article describes the design and methods of the trial and provides a discussion of the underlying rationale for key design decisions.

Double-Blind Method↗
PubMed1996

A new method for the treatment of fibromas: interstitial laser hyperthermia using the Nd:YAG laser. Preliminary study.

Operative laparoscopy can replace hysterectomy in the treatment of submucous and subserosal uterine fibromyomas. Interstitial myomas are still treated using traditional methods. Using an Nd:YAG laser with a quartz fibre which diffuses the ray, we induced delayed necrosis of myoma secondary to the hyperthermia produced by this method-interstitial laser hyperthermia. We present an experimental study of fibromas from excised tissue. Optimal efficiency is achieved with continuous delivery at 5 W of power for 10 min. The temperature reaches 50 degrees C within a radius of 20 mm around the fibre. A clinical study was undertaken with the approval of the Ethics Committee. Seven patients suffering from symptomatic fibromas were treated by laparoscopy. Preliminary results at 12 months show that their symptoms have disappeared and the size of the fibromas has been reduced. A larger study is in progress.

Adult↗
PubMed2006

Functional imaging with laser speckle contrast analysis: vascular compartment analysis and correlation with laser Doppler flowmetry and somatosensory evoked potentials.

Laser Speckle Contrast Analysis (LASCA), a novel, high-resolution blood flow imaging method, was performed on rat somatosensory cortex during functional activation. In the same animals, cerebral blood flow (CBF) was measured with Laser Doppler Flowmetry. To obtain a quantitative estimate of the underlying neuronal activity, somatosensory evoked potentials were recorded simultaneously with an epidural EEG. Our results show that: 1. CBF changes measured by LASCA or LDF are nonlinearly dependent on the magnitude of electrical neural activity revealed by somatosensory evoked potentials. 2. The magnitude of relative CBF changes measured by LASCA and LDF shows a strong correlation. 3. LASCA imaging localizes the highest relative changes of CBF in microcirculatory areas, with a smaller contribution by larger vessels. This study demonstrates that LASCA is a reliable method that provides 2D-imaging of CBF changes that are comparable to LDF measurements. It further suggests that functional neuroimaging methods based on CBF enhance areas of microcirculation and thus might prove more accurate in localizing neural activity than oxygenation related methods like BOLD-fMRI.

Animals↗
PubMed2004

Comparison of wavefront aberration changes in the anterior corneal surface after laser-assisted subepithelial keratectomy and laser in situ keratomileusis: preliminary study.

PURPOSE: To compare changes in anterior corneal wavefront aberrations after myopic laser-assisted subepithelial keratectomy (LASEK) and laser in situ keratomileusis (LASIK). SETTING: Institute of Ophthalmology, Catholic University, Rome, Italy. METHODS: This prospective study included 36 eyes of 25 myopic patients: 18 eyes of 12 patients had LASEK and 18 eyes of 13 patients, LASIK. The topography data (CSO EyeMap, version 6.2) were used to calculate corneal aberrations with 3.0 mm and 7.0 mm pupils before and 3 months after surgery. RESULTS: Total corneal aberrations increased similarly after LASEK and LASIK with the 7.0 mm pupil but did not change with the 3.0 mm pupil. Coma-like and spherical-like aberrations changed similarly after both procedures, but spherical-like aberrations increased after LASEK with the 3.0 mm pupil (P<.05, independent t test). With the 7.0 mm pupil, the amount of achieved correction was positively correlated with changes in total corneal aberrations after LASIK (P =.007) and with spherical-like aberrations after LASEK (P =.03) and LASIK (P<.003). Although there was no significant difference between LASEK and LASIK (P>.05, independent t test), in individual eyes with an achieved correction less than 7.50 diopters (D), spherical-like aberrations increased more after LASEK than after LASIK. CONCLUSIONS: In this preliminary study, myopic LASEK and LASIK changed total and higher-order corneal aberrations. In both procedures, changes in spherical-like aberrations were dependent on the achieved correction. However, in individual eyes, spherical-like aberrations increased more after LASEK than after LASIK for low-moderate achieved correction, suggesting that these procedures may induce the same optical changes in the anterior corneal surface in different ways.

Adult↗
PubMed2005

Complex formation of neptunium(V) with 4-hydroxy-3-methoxybenzoic acid studied by time-resolved laser-induced fluorescence spectroscopy with ultra-short laser pulses.

The complex formation of neptunium(V) with 4-hydroxy-3-methoxybenzoic acid (vanillic acid) was studied by time-resolved laser-induced fluorescence spectroscopy with ultra-short laser pulses using the fluorescence properties of 4-hydroxy-3-methoxybenzoic acid. A 2:1 complex of neptunium(V) with 4-hydroxy-3-methoxybenzoic acid was found. The stability constant of this complex was determined to be logbeta(210) = 7.33 +/- 0.10 at an ionic strength of 0.1 mol/l (NaClO(4)) and at 21 degrees C. The determination of the stability constant required an investigation of the excited-state proton transfer of 4-hydroxy-3-methoxybenzoic acid over the whole pH range. It was realized that 4-hydroxy-3-methoxybenzoic acid undergoes excited-state reactions only at pH values below 5. At pH values above 5 stability constants can be determined without kinetic calculation of the proton transfer.

Hydrogen-Ion Concentration↗
PubMed1985

Superficial laser vulvectomy. II. The anatomic and biophysical principles permitting accurate control over the depth of dermal destruction with the carbon dioxide laser.

The rationale for using the carbon dioxide laser to treat either vulvar intraepithelial neoplasia or extensive papillomaviral infections is to destroy the entire area of abnormal epithelium to a shallow depth, so that rapid healing will occur from normal keratinocytes in the underlying pilosebaceous glands. After the first laser impact, anatomic landmarks in the crater base are disguised by a layer of charred proteins, and any structure that is visible will already have suffered thermal necrosis. Accurate control of depth depends upon special surgical strategies that correlate the level of the underlying zone of thermal necrosis with specific visual appearances within the zone of vaporization. Maneuvers that limit depth of penetration to one of three desirable surgical planes (basement membrane, papillary dermis, midreticular dermis) are described.

Animals↗
PubMed1996

Undercorrection after excimer laser refractive surgery. Excimer Laser Group.

PURPOSE: The incidence and correlations of undercorrection were studied for 1 year after excimer laser surgery for myopia or myuopic astigmatism. METHODS: A consecutive series of 645 eyes of 440 patients were studied. Eyes were examined preoperatively and at 1, 3, 6, and 12 months after surgery. The parameters evaluated were visual acuity, refraction, and corneal clarity. RESULTS: Following excimer laser surgery, undercorrection of > or = -1.00 diopters gradually increased from 10% at 1 month to 40% at 12 months. Increasing degree of preoperative myopia was significantly associated with increasing occurrence of undercorrection at 3 months (chi 2 = 17.3, P < .001), 6 months (chi 2 = 53.6, P < .001), and 12 months (chi 2 = 64.8, P < .001). Undercorrection was more common in eyes that had had photorefractive keratectomy than in those that had had photoastigmatic refractive keratectomy (odds ratio, 0.40; 95% confidence interval, 0.25 to 0.60). At 1 year, a loss of 2 or more lines of best-corrected visual acuity was recorded in 38% of undercorrected patients. Loss of 2 or more lines of best-corrected visual acuity was more common in patients undercorrected by -1.00 diopter or more (odds ratio, 8.8; 95% confidence interval, 5.4 to 14.6). No relationship was seen between corneal haze and loss of best-corrected visual acuity. Undercorrection was not associated with age, gender, use of nonsteroidal anti-inflammatory drugs, bandage contact lens wear, or corneal haze. Patients with lower degrees of myopia reached a stable refraction more quickly. At 6 months, 71% were within +/- 0.5 diopter of 1-year refraction. Of 17 patients with undercorrection who were treated with topical corticosteroids, only one patient showed a permanent beneficial change. CONCLUSION: Occurrence of undercorrection is more common in patients with severe myopia and when simultaneous astigmatic corrections are undertaken.

Adult↗
PubMed1996

Comparison of results of excimer laser correction of all degrees of myopia at 12 months postoperatively. The Melbourne Excimer Laser Group.

UNLABELLED: To examine prospectively the efficacy and safety of photorefractive keratectomy and photoastigmatic refractive keratectomy. METHODS: We treated 645 eyes (440 patients) with a VisX Twenty/Twenty excimer laser and followed them up for 12 months. RESULTS: The percentage of eyes with myopia between -5.01 and -10.00 diopters spherical equivalent within 1 and 2 diopters of emmetropia at 12 months was 65% (123 of 189) and 90% (170 of 189), respectively, whereas the corresponding percentages for eyes with myopia greater than -10.00 diopters spherical equivalent were 39% (16 of 41) and 56% (23 of 41), and for eyes with myopia of -5.00 diopters spherical equivalent or less, 87% (238 of 273) and 99% (270 of 273), respectively. Uncorrected visual acuity of 20/20 and 20/40 or better at 12 months was attained in 47% (129 of 273) and 87% (237 of 273) of the eyes with myopia -5.00 diopters spherical equivalent or less, respectively. At 12 months, 48 (25%) of the 189 eyes with myopia between -5.01 and -10.00 diopters spherical equivalent had uncorrected visual acuity of 6/6 or better and 135 (71%), 6/12. At 12 months, one eye (2%) with myopia greater than -10.00 diopters spherical equivalent had uncorrected visual acuity of 6/6 and 11 (27%) of 41 eyes, 6/12. Ten (4%) of the 273 eyes with myopia of -5.00 diopters spherical equivalent or less, 15 (8%) of the 189 eyes with myopia between -5.01 and -10.00 diopters spherical equivalent, and nine (22%) of the 41 eyes with myopia greater than -10.00 diopters spherical equivalent had lost two or more LogMAR lines of best-corrected visual acuity at 12 months. CONCLUSION: Excimer laser surgery is highly reliable for myopia of -5.00 diopters spherical equivalent or less and is less reliable for greater myopia.

Adult↗
PubMed1983

Influence of the number of laser burns administered on the early results of argon laser trabeculoplasty.

We conducted a prospective, randomized, double-masked study to examine the influence of the number of burns administered on intraocular pressure after argon laser trabeculoplasty. Each of 40 patients with open-angle glaucoma had 50 burns placed over one half the trabecular meshwork (Group 1, 20 patients) or 100 burns placed over the entire trabecular meshwork (Group 2, 20 patients). There was no significant difference between the mean intraocular pressure decreases in Group 1 (-9.20 +/- 6.43 mm Hg) and Group 2 (-6.95 +/- 5.74 mm Hg) after two months (P less than .25). In each group, the intraocular pressure was lowest after two months in those patients in whom it was not increased during the immediate postoperative period (Group 1, P less than .006; Group 2, P less than .07). Because the changes in intraocular pressure were statistically similar in the two groups and because patients receiving only 50 burns may have fewer complications, administering 50 laser burns to one half the trabecular meshwork appears to be the better choice for an initial procedure.

Double-Blind Method↗
PubMed1996

Evaluation of wound healing of the teat with and without low level laser therapy in dairy cattle by laser Doppler flowmetry in comparison with histopathology, tensiometry and hydroxyproline analysis.

Perforated teat wounds in eight lactating Holstein-Friesian cows were closed by four suture patterns with or without low level laser therapy (LLLT). Wound healing was evaluated by laser Doppler flowmetry (LDF), tensiometry and hydroxyproline analysis, and compared with histopathological examination. The three-layer pattern provided the best healing of the entire teat. Mucosal hyperplasia was observed in Gambee and continuous two-layer pattern while eversion of the skin, presence of suture tracts and a greater amount of granulation tissue were observed with the continuous and interrupted two-layer patterns. The epidermis in LLLT groups more closely resembled the normal epidermis, and collagen fibres were denser, thicker and better arranged in LLLT than in non-LLLT groups. LDF, tensiometry and hydroxyproline analysis correlated well with histopathological examination. The results suggest that LDF, a more rapid, less invasive and painless procedure, can replace tensile strength measurement or hydroxyproline analysis to assess the progress of teat wound healing.

Animals↗