Palladium‐induced Th2 cytokine responses reflect skin test reactivity

Recently, a crucial role of Th2 responses in nickel allergic contact dermatitis (ACD) was demonstrated. As palladium allergy is an issue of growing interest, the diagnostic potential of Th2 parameters for palladium sensitization was investigated. Palladium (Na₂[PdCl₄])‐induced lymphocyte proliferation (LPT), Th1 and Th2 cytokine production were correlated with skin test (ST) reactivity in 16 positive and 21 negative controls. Furthermore, the diagnostic potential of these assays was evaluated using receiver operating characteristics (ROC) analysis. For comparison, same experiments were carried out for nickel (NiSO₄). Correlation coefficients between palladium ST reactivity and IFN‐γ, LPT, IL‐5, and IL‐13 were 0.34, 0.51, 0.69, and 0.78, and overall test accuracies were 68%, 81%, 89%, and 95%, respectively. Both palladium‐ and nickel‐mediated Th2 responses tightly correlate with ST reactivity, supporting recent findings on the crucial role of Th2 involvement in ACD. Therefore, these assays may have great potential as diagnostic tools for future in vitro sensitization testing.     

Ring‐Opening Copolymerization of 2‐Aryl‐1‐methylenecyclopropanes with Carbon Monoxide Initiated by Pd–bpy Complexes

[PdCl(Me)(bpy)] and a mixture of the complex with cocatalysts; NaBARF (BARF = [B{C₆H₃(CF₃)₂‐3,5}₄]^?), NaBF₄, AgBARF, AgBF₄, and AgOTf, catalyze the copolymerization of 2‐phenyl‐1‐methylenecyclopropane with carbon monoxide to produce a new polyketone accompanied by ring opening of the monomer. ¹H and ¹³C{¹H} NMR spectra indicate that the polymers have two isomeric repeating units in which the phenyl substituents occupy different positions. The molecular weights of the polyketones formed by the reactions with a [Pd]/[cocatalyst]/[2‐phenyl‐1‐methyleneyclopropane] ratio of 1:3:70 are in the range of M _n = 13 100–86 000. The polymer obtained by the reaction promoted by [PdCl(Me)(bpy)]/MBARF, where M = Ag or Na, shows a narrow molecular weight distribution, M _w/M _n = 1.44 and 1.59, respectively. The catalysis is effective also for the ring‐opening copolymerization of 2‐aryl‐1‐methylenecyclopropanes bearing Me and F substituents on the phenyl ring. Isotope‐labeled experiments revealed the mechanism of the polymerization, which involves a 1,2‐insertion of the monomer into the Pd–acyl bond to produce a cyclopropylmethyl palladium intermediate, and subsequent β‐alkyl elimination to give the Pd–alkyl complex.

     

Electroless Plating of High-Performance Composite Pd Membranes with EDTA-Free Bath

High-performance composite Pd membranes were successfully fabricated using electroless plating with an EDTA-free bath. The plating started with employing the one-time addition of hydrazine. In the experiment, the hydrazine concentrations and plating bath volumes were systematically varied to optimize the plating. The optimum composite Pd membrane tube showed high H₂ permeance of 4.4 × 10⁻³ mol/m² s Pa^0.5 and high selectivity of 1.6 × 10⁴, but poor cycling stability. Then, a method of sequential addition of the hydrazine from the high to low concentrations was employed. The resultant membrane, about 6 μm thick, still exhibited a high selectivity of 6.8 × 10⁴ as well as a much-improved plating yield and cycling stability level; this membrane outperformed the membrane made using the unmodified plating technique with the EDTA-contained bath. This result indicates the EDTA-free bath combined with the sequential addition of hydrazine is a simple, low-cost, yet effective method for preparing thin, dense composite Pd membranes featuring high hydrogen permeation flux and high thermal durability.     

Synthesis of iron–palladium binary alloy nanotubes by template-assisted electrodeposition from metal-complex solution

The ordered arrays of Fe–Pd binary alloy nanotubes were synthesized from the mixed metal-complex solution by a simple electrodeposition method with the assistance of nanoporous anodic alumina (AAO). The electrodeposition potentials of Fe²⁺ and Pd²⁺ can be controlled by complexing agents, which has allowed for the fabrication of the Fe–Pd nanotubes by the AAO-template-assisted electrodeposition. Furthermore, the adjustment of the cathodic current density has caused the variation of the inner diameters and Fe–Pd composition ratios of the alloy nanotubes. Although the as-prepared Fe–Pd nanotubes are comprised of f.c.c. crystal structures, the metastable phase structure has been converted to L1₂ supper-lattice structure by annealing. The results of this work have shown a potential applicability of AAO-template-assisted electrodeposition to the preparation of other new binary alloy nanotubes by selecting adequate complexing agents.     

Palladium in dental alloys – the dermatologists’responsibility to warn?

Palladium is increasingly used in industry, but also in fine jewellery and in dentistry. Thus, palladium-silver alloys comprise a substantial part of the noble metal ceramic alloy sales in Western countries. The increased use of this metal seems, however, to be paralleled by a rise in the number of reports of palladium allergy. Recently a European study reported a sensitization rate of 2.8%. In Austria, where palladium has started to displace amalgam in dental fillings because of concerns about mercury toxicity, and gold due to price factors, we have found a sensitization rate of 8.3% in unselected eczema patíents. Despíte the current lack of clear clinical relevance of this finding, these numbers should motivate us to question this substance as "the alloy of the future".     

Kontaktallergie auf Dentalmaterialien

The oral mucosa is constantly exposed to a large number of potentially irritating and sensitizing dental materials. Dental materials used for fillings and fixed or removable replacements must have a good biocompatibility. Metals including palladium are used in alloys for the production of the core of crowns, onto which porcelain is bonded for the generation of an artificial tooth to which the patient can develop an allergic contact dermatitis. The clinical manifestations of contact allergy to dental materials are not uniform. Objective symptoms of a contact allergy include a stomatitis and lichenoid reactions. However, patients may present with more subjective affections of the oral mucosa including burning, pain and dryness which need to be differentiated from a real contact allergic reaction. In this article we focus on the management of contact allergy to dental materials.     

The effect of the transfusion of stored RBCs on intestinal microvascular oxygenation in the rat

BACKGROUND: Although it is known that the transfusion of stored RBCs does not always improve tissue O(2) consumption under conditions of limited tissue oxygenation, the efficiency of O(2) delivery to the microcirculation by stored RBCs has never been determined. STUDY DESIGN AND METHODS: In a rat hemorrhagic shock model, the effects of resuscitation with fresh or 28-day-old RBCs stored in CPD plasma, saline-adenine-glucose-mannitol, and CPDA-1 plasma were investigated. Systemic hemodynamic and intestinal oxygenation measures were monitored. Intestinal microvascular PO(2) was determined with the O(2)-dependent quenching of palladium-porphyrin phosphorescence, and the RBC deformability was measured with a Laser-assisted optic rotational cell analyzer. RESULTS: Hemodynamic and oxygenation measures were significantly decreased during hemorrhagic shock. Intestinal oxygen consumption and mesenteric venous pO(2) were restored with the transfusion of both fresh and stored RBCs, except for CPD-stored RBCs. The intestinal microvascular pO(2) improved only with the transfusion of fresh RBCs. Deformability of the stored RBCs was significantly decreased. CONCLUSION: In contrast to that of fresh RBCs, the transfusion of stored RBCs did not restore the microcirculatory oxygenation, possibly because of impaired O(2) unloading, but, except for CPD-stored RBCs, the storage-induced changes were not enough to impair intestinal VO(2) and mesenteric venous pO(2).     

超声诊断乳腺肿块的临床价值及钼靶对照分析

目的：评估超声对乳腺肿块的诊断价值。方法：对71例乳腺肿块患者进行超声及钼靶检查,并分别与病理对照。结果：良恶性乳腺肿块的声像图有明显差异。超声对良恶性乳腺肿块的诊断正确率分别为91.3%,84.0%。钼靶为58.7%,72.0%。结论：二维彩色多普勒超声对乳腺肿块的诊断具有优势。     

Investigations into the C‐deuteriation of silyl enol ethers derived from aryl alkyl ketones

Results are reported on the regioselective C‐deuteriation of a series of silyl enol ethers derived from aryl alkyl ketones using deuterium (D₂) gas as the deuterium source and palladium‐on‐barium sulfate as the mediator. These results highlight the numerous reaction pathways and different product types available from simple deuteriation of substituted enol precursors. Copyright © 2006 John Wiley & Sons, Ltd.