[Drug allergy: new methodological approaches in occupational clinical evaluations]. / Farmacoallergia. Disamina di una casistica e nuovi approcci metodologici in ambito occupazionale.

Drug reactions in pharmaceutical industry workers represent a quiet different problem in terms of evaluation and job ability, if related to hospitalized patients with adverse reaction to drug administration. The modern approach of GRADE (Grading Recommendation Assessment Development and Evaluation) was applied to 8 workers who had suspected occupational drug reactions, and were clinically examined in order to exclude any possible adverse event. Such a method allows to draw the relationship between adverse reaction to drugs, aetiology, risk evaluation and clinical events. Therefore, the adverse events are classified in type A (incongruous exposure), type B (hypersensitivity reactions) and not A not B (not work related). Both medical history/clinical evaluation and GRADE seem to give a correct view of the single case. Moreover, a high score suggests an occupational pathology, whilst low scores for evidence of drug reaction and occupational risk can avoid the use of diagnostic procedures.

Chronic urticaria: novel clinical and serological aspects.

BACKGROUND: Recently, distinct studies have shown that: (a) chronic idiopathic urticaria (CIU) is autoimmune in 30-50% of cases; (b) in patients with CIU the autologous serum skin test is inhibited by heparin; and (c) basophil histamine release induced in vitro by CIU sera maybe complement-dependent. OBJECTIVE: To carry out a comprehensive clinical and serological study on CIU based upon these observations. METHODS: Three hundred and six adults with CIU underwent intradermal (ID) test with autologous serum; 57 of them with autologous heparinized plasma as well. Sera from 121 patients (plasmas from 17) were employed to induce in vitro histamine release from basophils of normal donors. The effects of heating (56 degrees C, 60 min), filtration through membrane, and preincubation with heparin were evaluated as well. RESULTS: Autologous serum and plasma induced a weal and flare reaction in 205 out of 306 (205/306; 67%) and in 8/57 (14%) patients, respectively. Positive plasma skin tests were observed only in patients showing strongly positive serum skin tests. Plasma did not elicit any skin reaction in 3/3 patients with dermatographism who showed a positive intradermal test with saline. Sera from 20/121 (16.5%) patients induced significant histamine release from basophils of normal donors. 19/20 sera were from patients with a positive intradermal test; thus, basophil histamine release assay was positive in 19/87 (21.8%) patients with a positive serum skin test. Heating at 56 degrees C x 1 h markedly reduced the histamine-releasing activity of both serum and plasma from in vitro reactors. Ultrafiltered fractions > 100 kDa of both sera tested retained the histamine-releasing activity, whereas fractions < 100 kDa were not able to induce any histamine release. Heparin dose-dependently inhibited histamine release induced by sera and plasma, and by basophil agonists such as anti-IgE, formyl-methionyl-leucyl-phenilalanine, and interleukin (IL)-3. CONCLUSIONS: 67% of our patients with CIU showed a positive autologous serum skin test. Sera from about 20% of those positive on autologous serum skin test induced histamine release from normal basophils in vitro probably as a consequence of the presence of functional autoantibodies. The marked difference between in vivo and in vitro findings could reflect the existence of a mast cell-specific histamine-releasing factor which does not release histamine from basophils of healthy blood donors. However, it might be also the result of in vivo priming of patients' cutaneous mast cells or of heterogeneity of basophil donors. At least in some cases complement seems essential for histamine-releasing activity of serum from patients with CIU. Heparin inhibits histamine release from both basophils (in vitro) and mast cells (in vivo), probably acting directly at a cellular level.

Determination of cut-off positivity values in nasal challenge testing of patients with allergic rhinitis.

Nasal challenge testing with allergen extracts is currently used to diagnose nasal allergy and, to a greater extent, in studies of pathophysiology of allergic rhinitis. The resulting nasal obstruction, measured as nasal airway resistance (NAR), is determined by rhinomanometry (RMM). The aim of this study was to define a cut-off NAR value for a positive response in a nasal allergen challenge test. Forty-two, grass-allergic adult patients and 40 nonallergic adults were challenged out of the grass pollen season under standard conditions with timothy grass extract administered intranasally in doses increasing from 10 to 1500 IU/mL. Inspiratory NAR was determined by computerized anterior active RMM. The cut-off value for a positive test was determined from receiver operating characteristic curves plotted from these data with the LABROC1 computer program. In addition, the subjects' nasal cycle was recorded during the four hours preceding the allergen challenge. The patients' mean NAR value at baseline (0.33 Pa/cc/sec) and when challenged with normal saline solution did not differ from those of the control subjects. The patients, but not the control subjects, experienced typical nasal allergic symptoms when challenged with the grass extract. The control subjects had no symptoms and their NAR did not change significantly when they were challenged with the same extract. All 42 allergic patients had measurable increases in NAR at the 800 IU/mL allergen dose; 19/42 patients had complete obstruction (i.e., NAR unmeasurable) when challenged with the 1500 IU/mL dose. The maximum diagnostic value (= sensitivity + specificity at the discriminator position on the receiver operating characteristic curves) was 1.96 with the 800 IU/mL dose. At that dose, the NAR cut-off value was 0.91 Pa/cc/sec, which was 2.7 times greater than their mean value at baseline. NAR varied less than 1-fold between the maximum and minimum points of the normal nasal cycle in both groups of subjects. An increase of NAR of nearly three-fold during nasal allergen challenge compared to the baseline value determined by computerized anterior active RMM discriminates best patients with allergic rhinitis from nonallergic adults.

Intraocular measurements of pressure transients induced by excimer laser ablation of the cornea.

BACKGROUND AND OBJECTIVE: The evolution of pressure waves induced by argon-fluoride laser ablation of the cornea in the typical operative conditions of clinical laser keratectomy has been studied experimentally and analyzed. MATERIALS AND METHODS: Freshly enucleated porcine eyes were irradiated at a laser fluence of 180 mJ/cm2 with various spot diameters in the range 1-6.5 mm. Pressure transients were detected by a fast rise time needle hydrophone inserted into the eyeball from the posterior pole and moved along the eye optical axis toward the cornea. RESULTS: Pressure peaks as high as 90 bar and 50 ns pulse duration (FWHM) were measured in the anterior chamber. Observation of the pulse shape evolution during propagation put in evidence the onset of a marked rarefaction phase following the compressional spike, with intense negative peaks (up to -40 bar) located at increasing distances from the corneal surface for increasing spot diameters. CONCLUSIONS: This behavior was explained by means of simplified models describing pressure pulse generation and diffraction effects occurring during its propagation. Implications to clinical procedures, as possible damages due to tissue stretching and cavitation formation, are also discussed.

Cleaning processes of encrusted marbles by Nd:YAG lasers operating in free-running and Q-switching regimes.

The removal process of degraded superficial layers from marble samples by Nd:YAG lasers was studied while simulating operative conditions of stone artwork restoration. The effects of laser irradiation at 1064 nm with three different pulse durations of 6 ns, 20 micros, and 200 micros were investigated by time-resolved shadowgraphy and emission spectroscopy of the ejection plume to characterize the specific interaction regimes, with particular concern given to the occurrence of side effects, such as thermal and mechanical damages to the substrate, that could affect the laser cleaning procedure.

Time-dependent analysis of a parametric lens detected with a 100-fs Ti:sapphire laser.

The second-order parametric lens effect shows a temporal limit as a saturable-absorber device for operation in the ultrafast time region. We present and discuss an extended theoretical model dealing with second-order cascaded processes in a nonstationary condition. Experimentally we report the detection of the time-averaged lens effect in the hundred-of-femtoseconds range, discussing the limits that arise in this ultrafast optical region.

Efficient second harmonic generation in beta-barium borate by a diffraction-limited copper vapor laser.

The diffraction-limited beam of a copper vapor laser employing a self-filtering unstable resonator was used to induce second harmonic generation in a nonlinear crystal of beta-barium borate. Despite the moderate emission characteristics of our small-scale laser device (1.5-W average power, 25-kW peak power at 511 nm), we obtained average and peak power conversion efficiencies of approximately 20 and 30%, respectively, which improved on the previously reported results by a factor of 2.

Laser dentistry: a new application of excimer laser in root canal therapy.

We report the first study of the application of excimer lasers in dentistry for the treatment of dental root canals. High-energy ultraviolet (UV) radiation emitted by an XeCl excimer laser (308 nm) and delivered through suitable optical fibers can be used to remove residual organic tissue from the canals. To this aim, UV ablation thresholds of dental tissues have been measured, showing a preferential etching of infiltrated dentin in respect to healthy dentin, at laser fluences of 0.5-1.5 J/cm2. This technique has been tested on extracted tooth samples, simulating a clinical procedure. Fibers of decreasing core diameters have been used to treat different sections of the root canal down to its apical portion, resulting in an effective, easy, and fast cleaning action. Possible advantages of excimer laser clinical applications in respect to usual procedures are also discussed.

Laser dentistry: root canal diagnostic technique based on ultraviolet-induced fluorescence spectroscopy.

A diagnostic technique to detect residual tissues at different levels of the root canal during an endodontic treatment is presented. The diagnostic system is based on ultraviolet-induced fluorescence spectroscopy and uses suitable optical fibers for local delivery of excitation light and to collect back fluorescence spectra. Spectra of root canal tissues have been obtained from split teeth by labeling with a fluorescent solution. Residual tissue can be discriminated in respect to healthy dentin because of their different spectral responses: the spectral shape of the first response shows a clear peak at 530 nm because of a selective absorption of the fluorescent dye, whereas for the second response, the spectral curve monotonically increases toward ultraviolet wave-lengths with no particular structure. This technique has been tested on unsplit teeth simulating operative conditions. A compact spectroscopic system has been devised that can be easily integrated in an excimer laser system to perform residual tissue detection during laser cleaning of the canals.

Optical fiber transmission of high power excimer laser radiation.

An experimental investigation of optical fiber transmission of high power excimer laser radiation is presented. Different types of commercially available UV fiber have been tested, measuring energy handling capabilities and transmission losses of short samples at the XeCl (308-nm) and KrF (249-nm) wavelengths by using a standard excimer laser. A power density dependent damage process has been observed over 1 GW/cm(2). Fiber losses due to different radii of curvature are also reported. Experimental results have been examined to evaluate the effectiveness of excimer laser transmission through optical fibers for such medical uses as laser angioplasty, including also a comparison between the use of KrF or XeCl emission lines for this purpose. Finally, optimum excimer laser characteristics to increase the energy coupling in fibers are discussed.

Continuously tunable multiple-order stimulated four-photon mixing in a multimode silica fiber.

Stimulated four-photon mixing (SFPM) has been observed up to four orders in a 300-m-long, low-loss, large-core multimode silica fiber pumped by a dual-frequency dye laser. The phase-matching condition for SFPM was uncritically achieved in the multimode fiber, so that, by varying the frequency separation of the two laser lines, it was possible to tune continuously an intense line generated by SFPM under the Raman-gain curve in the range of 350 to 495 cm(-1).

Graded-gain dye laser amplifiers: an experimental investigation.

The influence of inhomogeneous distributions of gain and refractive index produced by the pumping radiationon the performance of dye laser amplifiers is discussed. Experimental measurements in capillary cylindrical cells and planar cells are reported for single-pass, double-pass, and ring configurations. Gain factors up to 8.5 x 10(4) have been obtained at low signal input with rhodamine 6G in ethanol. A saturated gain of 5 x 10(3) at 100-mJ output with an over-all efficiency of 0.1% has been achieved without full optimizationof the amplifier parameters. The reported results indicate that a two-stage double-pass amplifier driven by a dye laser oscillator in the milliwatt region can be used as an efficient high energy light source.