Molecular structure and concentration of melanin in the stratum corneum of patients with melasma

Melasma is an abnormal acquired hyperpigmentation of the face of unknown origin, it is considered a single disease and very little has been found regarding its pathogenesis. It is usually assumed that melasma is due to excessive melanin production, but excessive retention or abnormal metabolism of this molecule has not yet been considered. In order to search for an alternate explanation for the excessive pigmentation in melasma the molecular structure and concentration of melanin in the stratum corneum of patients with melasma was analyzed using Raman spectroscopy and optical transmission spectroscopy, respectively. From this study it became apparent that in melasma melanin is concentrated in the deeper layers of the skin but its exteriorization remains the same as for healthy skin. Raman spectroscopy measurements showed degraded molecules of melanin in some subjects, which may help explain the variable success rate of the standard therapy.     

Evaluation of Phase Stability in Zirconia Femoral Heads From Different Manufacturers After In Vitro Testing or In Vivo Retrieval

Yttria-stabilized zirconia femoral heads from 3 different manufacturers were tested in vitro with respect to their phase stability and compared with retrieved zirconia heads. The monoclinic content on the surface of unused heads was analyzed by confocal Raman spectroscopy after exposure for increasing times to moist atmosphere. The increase in monoclinic content was then plotted as a function of geometric location on the head surface of the head and compared with that measured at similar locations after in vivo exposure. Profiles of residual stress associated to polymorphic transformation were also measured from the collected Raman spectra. A striking finding was that, in some samples, polymorphic transformation occurred since the very early stage of the environmental exposure even if those samples belonged to new-generation products.     

Er：YAG激光照射后牙本质的分子研究

目的：用拉曼分光光度计评价使用激光照射前后和酸蚀前后人牙本质中有机物和无机物的组成情况。方法：收集6颗无龋的人第三磨牙,去除咬面釉质,制成6个牙本质板,每个板分为四个区,每个区采用不同的表面处理：（对照组）37%的磷酸凝胶酸蚀;（Ⅰ组）80 mJ,3Hz,30s的Er：YAG激光照射（DEKA Smart2940D）;（Ⅱ组）120 mJ,3Hz,30s的Er：YAG激光照射;（Ⅲ组）180 mJ,3Hz,30s的Er：YAG激光照射。使用拉曼光谱对各组的有机质和无机质成分进行检测并评价。结果：对照组和I组的成分几乎没有改变（P〉0.05）;Ⅱ组有较多无机物的丧失（P〈0.01）;而Ⅲ组无机物（P〈0.05）与有机物（P〈0.01）均有明显减少。结论：拉曼分光光度计是研究牙本质化学成分的有效有段。180mJ的Er：YAG激光照射后,牙本质的分子成分有明显改变。     

不同类型视网膜脱离患者视网膜下积液蛋白质结构分析

为比较不同类型视网膜脱离（ＲＤ）患者视网膜下积液（ＳＲＦ）蛋白质结构的异同，我们用傅里叶拉曼（ＦＴＲａｍａｎ）和傅里叶红外（ＦＴＩＲ）光谱测定不同类型ＲＤ患者血清及ＳＲＦ蛋白质结构。结果发现不同类型ＲＤ患者血清的两种光谱很相似，但的析两各光谱因类型和病程而异。不同类型ＲＤ患者ＳＲＦ不仅有芳香族结构明显改变，而且脂蛋白结构也有改变。     

拉曼光谱在口腔诊疗中的研究进展

拉曼光谱可检测生物组织中脂质、核酸、蛋白质、水分子等结构和组成信息,在医学领域中被广泛应用.目前口腔疾病的检查诊断主要依靠影像学检查.随着科学技术的发展,拉曼光谱在口腔医学领域的研究也取得了较大的进展,本文就拉曼光谱的原理、优势以及应用作一综述.     

Quantification of monomer elution and carbon–carbon double bonds in dental adhesive systems using HPLC and micro-Raman spectroscopy

Objectives

To quantify monomer elution from different adhesive systems using reverse-phase high-performance liquid chromatography (HPLC) and correlate this elution with the ratio of carbon–carbon double bonds from monomer to polymer (RDB) obtained using micro-Raman spectroscopy.

Methods

Thirty dentine discs were cut from 30 human, intact, third molars and randomly allocated to five groups according to the adhesive applied: total-etch, Excite (Ivoclar Vivadent), two-bottle self-etch, Clearfil SE (Kuraray), one-bottle self-etch, Clearfil 3S (Kuraray), ormocer-based, Admira (Voco) and Filtek Silorane adhesive system (FS) (3M ESPE). Monomer elution was studied 1 h, 6 h, 24 h, 96 h and 7 days after immersion in 75% ethanol/water. The RDB was calculated immediately after light-curing and thereafter at 24 h and 7 days. The data were statistically analysed using one-way ANOVA and Pearson's correlation coefficient (p < 0.05).

Results

More than 90% of the whole elution occurred during the first 1 h, except for BisGMA in FS, with the highest absolute amount from Clearfil SE and the highest wt% from Admira. Initial RDB was in the ascending order FS < Admira < Excite < Clearfil SE < Clearfil 3S. In all groups, the RDB was significantly higher after 24 h and 7 days than immediately after light-curing (p < 0.05). Negative correlation was found only for the elution of HEMA and the RDB of Clearfil 3S.

Conclusions

Different adhesive systems showed different monomer elution kinetics. In all systems, the RDB increased after monomer elution. Overall, no direct correlation exists between the RDB of adhesives and the elution of unreacted monomers.     

口腔鳞状细胞癌近红外拉曼光谱特征及其诊断价值研究

目的探索近红外拉曼光谱技术及化学计量法在口腔鳞状细胞癌诊断中的应用价值。方法收集正常口腔黏膜组织10例、鳞状细胞癌组织20例、白斑30例进行近红外拉曼光谱扫描,分析不同病变类型的特征性光谱,通过化学计量法进行分析建模,并评价其分类诊断效力。结果相对于正常组织,鳞状细胞癌及白斑中DNA、蛋白及脂类合成增强,表现出较明显的增殖活性。在对鳞状细胞癌和正常组织的建模比较中,诊断准确度98.81％;在鳞状细胞癌与白斑建模诊断中,诊断准确度96.30％。结论近红外拉曼光谱检测结合支持向量机分类建模技术,可以检测到口腔正常黏膜、白斑及鳞状细胞癌样本中的生化物质变化,并进行准确分类建模诊断。     

Raman spectroscopy for differential diagnosis of endophthalmitis and uveitis in rabbit iris in vitro

We developed a diagnostic tool to differentiate between endophthalmitis and uveitis using Raman spectroscopy. Twenty-two New Zealand rabbits with endophthalmitis induced by Staphylococcus aureus (10 animals), noninfectious uveitis induced by lipopolysaccharide from Escherichia coli (10 animals) and controls (two animals) were analyzed. Twenty-four hours after the eyes were inoculated, iris tissue was dissected and subjected to dispersive Raman spectroscopy using an excitation source at 830 nm and a spectrograph/CCD camera to detect a Raman signal with an integration time of 50 s. With the collected spectra of endophthalmitis and uveitis, we developed a routine to classify spectra in each specimen using principal components analysis, using a leave-one-out cross-validation procedure. The mean Raman spectra of tissues with uveitis and endophthalmitis showed several bands in the region of 800-1800 cm⁻¹, which have been attributed to nucleic acids, amino acids, proteins, and lipids. The bands at 1004, 1339, and 1555 cm⁻¹ differed significantly (t-test, p < 0.05) between diseases. The principal components PC3 and PC4 differed significantly (ANOVA, p < 0.05) for the two tissue types, indicating that these PCs can be used to discriminate between the two diseases using Mahalanobis distance as a discriminator. This technique is useful for differentiating the spectral bands of uveitis and endophthalmitis, and the diagnostic model showed sensitivity of 89%, specificity of 100%, and accuracy of 92% using the leave-one-out cross-validation procedure. These results may be clinically relevant for differentiating endophthalmitis from uveitis, and this approach may become a noninvasive method to optimize the diagnosis of inflammatory and infectious vitreoretinal diseases.     

Oxidation of MBE-Grown ZnTe and ZnTe/Zn Nanowires and Their Structural Properties

Results of comparative structural characterization of bare and Zn-covered ZnTe nanowires (NWs) before and after thermal oxidation at 300 °C are presented. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and Raman scattering not only unambiguously confirm the conversion of the outer layer of the NWs into ZnO, but also demonstrate the influence of the oxidation process on the structure of the inner part of the NWs. Our study shows that the morphology of the resulting ZnO can be improved by the deposition of thin Zn shells on the bare ZnTe NWs prior to the oxidation. The oxidation of bare ZnTe NWs results in the formation of separated ZnO nanocrystals which decorate crystalline Te cores of the NWs. In the case of Zn-covered NWs, uniform ZnO shells are formed, however they are of a fine-crystalline structure or partially amorphous. Our study provides an important insight into the details of the oxidation processes of ZnTe nanostructures, which could be of importance for the preparation and performance of ZnTe based nano-devices operating under normal atmospheric conditions and at elevated temperatures.