Sensitizing potential of urethane (meth)acrylates in the guinea pig

Urethane (meth)acrylates are used as prepolymers in ultraviolet-curable inks, varnishes and coating formulations for industrial purposes as well as resins for dental applications. The sensitizing capacity of 3 commonly used urethane (meth)acrylates was investigated using the guinea pig maximization test. The study shows that an aliphatic urethane acrylate is not only a more potent sensitizer than an aromatic one, but also more sensitizing than a (meth)acrylated aliphatic urethane.     

压敏胶粘剂组成、结构及性能的研究进展

压敏胶粘剂是一种柔性可塑性固体物质，由于其具有良好的耐候、耐热、耐油性以及机械强度好等优点，正得到越来越多的应用。介绍了不同种类压敏胶的组成、结构和性能的研究进展。     

泡沫敷料对腋臭术后切口二期延迟愈合的疗效观察

目的探讨泡沫敷料治疗腋臭术后切口感染裂开的疗效。方法将30例腋臭术后切口感染裂开的患者随机分为实验组和对照组,各15例。实验组采用泡沫敷料进行换药治疗,对照组采用0．5％碘伏和凡士林纱布换药。结果实验组总显效率明显高于对照组（P〈0．01）,伤口愈合时间明显短于对照组（P〈O．01）,且更换敷料时疼痛明显减轻优于对照组（P〈O．01）。结论采用泡沫敷料明显提高了腋臭术后切口感染裂开的治疗效果,缩短了疗程,是一种有效的治疗方法。     

Biomimetic remineralization of human dentin using promising innovative calcium-silicate hybrid “smart” materials

Introduction

The hypothesis was that experimental ion-leaching bioactive composites enhance remineralization of apatite-depleted dentin.

Materials and methods

Calcium-aluminosilicate (wTC-Ba) or fluoride-containing calcium-aluminosilicate (FTC-Ba) Portland-derived mineral powders were mixed with HTP-M methacrylate HEMA/TEGDMA/PAA-based resin to prepare experimental composites. Controls were Vitrebond and Gradia Direct LoFlo.Calcium- and fluoride-release, pH of soaking water, solubility and water uptake were evaluated in deionized water using material disks (8 mm diameter and 1.6 mm thick).The apatite-formation ability (bioactivity) and the ability to remineralize previously demineralized dentin were assessed by ESEM-EDX and FTIR after soaking in a phosphate-containing solution.Human dentin slices (0.8 mm thickness) were demineralized in EDTA 17% for 2 h, placed in close contact with the material disks and immersed in a phosphate-containing solution (Dulbecco's Phosphate Buffered Saline, DPBS) to assess the ability of the materials to remineralize apatite-depleted dentin.

Results

Only the experimental materials released calcium and basified the soaking water (released hydroxyl ions). A correlation between calcium release and solubility was observed. FTC-Ba composite released more fluoride than Vitrebond and formed calcium fluoride (fluorite) precipitates. Polyacrylate calcium complexes (between COO⁻ groups of polyacrylate and released calcium ions) formed at high pH.The formation of apatite was noticed only on the experimental materials, due to the combination of calcium ions provided by the materials and phosphate from the DPBS. Apatite deposits (spherulites showing Ca and P EDX peaks and IR bands due to phosphate stretching and bending) were detected early on the experimental material disks after only 24 h of soaking in DPBS.Only the experimental composites proved to have the ability to remineralize apatite-depleted dentin surfaces. After 7 days in DPBS, only the demineralized dentin treated with the experimental materials showed the appearance of carbonated apatite (IR bands at about 1400, 1020, 600 cm⁻¹). EDX compositional depth profile through the fractured demineralized dentin slices showed the reappearance of Ca and P peaks (remineralization of dentin surface) to 30-50 μm depth.

Conclusions

The ion-leachable experimental composites remineralized the human apatite-depleted dentin. Ion release promotes the formation of a bone-like carbonated-apatite on demineralized dentin within 7 days of immersion in DPBS.The use of bioactive “smart” composites containing reactive calcium-silicate Portland-derived mineral powder as tailored filler may be an innovative method for the biomimetic remineralization of apatite-depleted dentin surfaces and to prevent the demineralization of hypomineralized/carious dentin, with potentially great advantage in clinical applications.     

基于听觉响应时间的麻醉效果监测

目的探索麻醉代谢过程中听觉系统相关参数的变化,为动物实验中麻醉效果的正确评估建立监测指标。方法选取4~6周的BALB/C小鼠,手术方法暴露下丘组织,用乌拉坦进行麻醉,选取纯音作为刺激条件,记录麻醉代谢过程中小鼠下丘的听觉局部电位波形,并用matlab软件提取波形的潜伏期和幅度数值,分析二者随麻醉剂的代谢而呈现的变化。结果与幅度相比,小鼠听觉局部电位的潜伏期数值变异性小,且与时间有较好的相关性。在乌拉坦代谢过程中,潜伏期随麻醉代谢过程逐渐下降,其中前2 h下降较快,后期逐渐趋于稳定。结论听觉局部电位的潜伏期比幅度更适合作为麻醉效果的监测指标。     

BOSC: A better oscillation detection method, extracts both sustained and transient rhythms from rat hippocampal recordings

Neuronal population oscillations at a variety of frequencies can be readily seen in electroencephalographic (EEG) as well as local field potential recordings in many different species. Although these brain rhythms have been studied for many years, the methods for identifying discrete oscillatory epochs are still widely variable across studies. The "better oscillation detection" (BOSC) method applies standardized criteria to detect runs of "true" oscillatory activity and rejects transient events that do not reflect actual rhythms. It does so by estimating the background spectrum of the actual signal to derive detection criteria that include both power and duration thresholds. This method has not yet been applied to nonhuman data. Here, we test the BOSC method on two important rat hippocampal oscillatory signals, the theta rhythm and slow oscillation (SO), two large amplitude and mutually exclusive states. The BOSC method detected both the relatively sustained theta rhythm and the relatively transient SO apparent under urethane anesthesia and was relatively resilient to spectral features that changed across states, complementing previous findings for human EEG. Detection of oscillatory activity using the BOSC method (but not more traditional Fourier transform-based power analysis) corresponded well with human expert ratings. Moreover, for near-continuous theta, BOSC proved useful for detecting discrete disruptions that were associated with sudden and large amplitude phase shifts of the ongoing rhythm. Thus, the BOSC method accurately extracts oscillatory and nonoscillatory episodes from field potential recordings and produces systematic, objective, and consistent results-not only across frequencies, brain regions, tasks, and waking states, as shown previously, but also across species and for both sustained and transient rhythms. Thus, the BOSC method will facilitate more direct comparisons of oscillatory brain activity across all types of experimental paradigms.     

Hydrophobic UV-Curable Powder Clear Coatings: Study on the Synthesis of New Crosslinking Agents Based on Raw Materials Derived from Renewable Sources

Methods for the synthesis of urethane acrylates used as new crosslinking agents for hydrophobic UV-curable powder clear coatings were developed. In the synthesis of urethane acrylates, isophorone diisocyanate, glycerin, xylitol, polyethylene glycol and polysiloxane KF-6000, as well as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, were used. In order to increase the functionality of urethane acrylates, glycerin and xylitol derived from renewable sources were introduced. The chemical structure of the urethane acrylates was verified by IR spectroscopy. UV-curable powder clear coatings were obtained through a combination of urethane acrylates with unsaturated polyester resins. The thermal behavior and crosslinking density were examined using DMA. The obtained coatings were evaluated by performing the following tests: roughness, gloss, scratch resistance, hardness, adhesion to steel and water contact angle. As part of this research, high hydrophobicity and scratch resistance of UV-curable powder clear coatings were developed, which are a VOC-free and economically attractive alternative method for low thermal resistance surface protection, such as for composites, wood and wood-based materials.     

A novel urethane acrylate-based root canal sealer with improved degree of conversion, cytotoxicity, bond strengths, solubility, and dimensional stability

Introduction

We have developed new urethane acrylate-based root canal sealers using polycarbonate (PC) as polyol and 2,2-azobis(2-methyl)butyronitrile (AMBN) as a thermal initiator. The purpose of this study was to compare the properties among a group of seven sealers: (1) polybutyleneadipate (PBA) with 2,2-azobis-isobutyronitrile (AIBN), (2) PBA-AMBN, (3) PC-AIBN, (4) PC-AMBN, (5) AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany), (6) Epiphany (Pentron Clinical Technologies, Wallingford, CT), and (7) EndoREZ (Ultradent Products, Inc, South Jordan, UT).

Methods

Attenuated total reflectance-Fourier transforming infrared spectroscopy was used to analyze the degree of conversion. Cytotoxicity was evaluated using MTT assay. In addition, push-out bond strength, solubility, and dimensional stability were investigated.

Results

Urethane acrylate-based root canal sealers behaved better than Epiphany and EndoREZ for the properties evaluated in this study. The PC-AMBN sealer exhibited the highest degree of conversion even in the apical third, and its cytotoxicity for nonsetting and aged specimens at 24 hours was comparable to AH Plus sealer. In addition, the PC-AMBN sealer with zinc oxide/thermoplastic polyurethane cones had a significantly higher bond strength than AH Plus with gutta percha. Solubility and dimensional changes of the PC-AMBN sealer conformed to the American National Standards Institute/American Dental Association (ANSI/ADA) standard 57.

Conclusions

The PC-AMBN sealer has great potential for use in endodontic therapy.     

Anti-serotonergic effects of urethane and chloral hydrate may not be mediated by a blockade of 5-HT2 receptors

Summary The general anesthetics urethane and chloral hydrate have profound anti-serotonergic effects both in the rat cortex in vivo and the rat aortic ring in vitro. The suggestion that these effects may be due to an action on 5-HT₂ receptors was tested using ex vivo and in vitro [³H]ketanserin binding assays with membrane-enriched fractions from rat brain. Urethane did not alter [³H]ketanserin binding in the ex vivo assay. In the in vitro assay, urethane, chloral hydrate, and its active metabolite 2,2,2-trichloroethanol produced slight reductions (of 16%, 9%, and 18%, respectively) of [³H]ketanserin binding. These studies suggest that anti-serotonergic effects of urethane and chloral hydrate may not be mediated by a blockade of 5-HT₂ receptors.