Early cortical lens opacities: a short overview

Cataract is still the dominant cause of blindness worldwide. Cortical cataract is the most prevalent of the age‐related changes in the human lenses that require surgical intervention to restore vision. The absence of adequate cataract surgery in most developing countries is the main cause of the high prevalence of cataract blindness worldwide. Lens ageing is accompanied by dramatic increases in stiffness, light scattering and coloration of the lens nucleus. These changes start to become manifest as early as the fourth or fifth decade of life and lead to nuclear cataract in old age. In the same period the equatorial deep lens cortex starts to show small opaque shades, which eventually grow out to segmental and annular opacities. These opaque shades are filled with small vesicles and contain abnormal amounts of cross‐linked proteins, cholesterol and phospholipids. They are bordered by membranes that are rich in square arrays, have ‘degenerate’ gap junctions and have few intramembranous particles. It has been shown that the opaque shades represent cohorts of locally affected fibres segregated from unaffected neighbouring fibres by ‘non‐leaky’ membranes. This segregation is an effective mechanism delaying the outgrowth of these opacities to cuneiform cataracts entering the pupillary space and thus leading to blinding cortical cataracts. Although cataract formation is mostly considered to be a multi‐factorial disease, oxidative stress might be one of the leading causes for both nuclear and cortical cataract. In cortical cataracts shear stress between cortex and nucleus during accommodation may also play a significant role.     

International amphibian micronucleus standardized procedure (ISO 21427‐1) for in vivo evaluation of double‐walled carbon nanotubes toxicity and genotoxicity in water

Considering the important production of carbon nanotubes (CNTs), it is likely that some of them will contaminate the environment during each step of their life cycle. Nevertheless, there is little known about their potential ecotoxicity. Consequently, the impact of CNTs on the environment must be taken into consideration. This work evaluates the potential impact of well characterized double‐walled carbon nanotubes (DWNTs) in the amphibian larvae Xenopus laevis under normalized laboratory conditions according to the International Standard micronucleus assay ISO 21427‐1:2006 for 12 days of half‐static exposure to 0.1–1–10 and 50 mg L^?1 of DWNTs in water. Two different endpoints were carried out: (i) toxicity (mortality and growth of larvae) and (ii) genotoxicity (induction of micronucleated erythrocytes). Moreover, intestine of larvae were analyzed using Raman spectroscopy. The DWNTs synthetized by catalytic chemical vapor deposition (CCVD) were used as produce (experiment I) and the addition of Gum Arabic (GA) was investigated to improve the stability of the aqueous suspensions (experiment II). The results show growth inhibition in larvae exposed to 10 and 50 mg L^?1 of DWNTs with or without GA. No genotoxicity was evidenced in erythrocytes of larvae exposed to DWNTs, except to 1 mg L^?1 of DWNTs with GA suggesting its potential effect in association with DWNTs at the first nonacutely toxic concentration. The Raman analysis confirmed the presence of DWNTs into the lumen of intestine but not in intestinal tissues and cells, nor in the circulating blood of exposed larvae. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010.     

微区喇曼光谱法区分周围神经束性质

BACKGROUND： A variety of methods have been used to identify and distinguish motor and sensory nerves. However, their application is limited clinically due to the complex operation, time consumption, and subjectivity. Raman spectroscopy is a minimally invasive method that provides information about molecular structure and constitutions and has been frequently used for tissue identification.
OBJECTIVE： To explore a time-efficient method of identifying motor and sensory fascicles in peripheral nerve trunk using laser micro-Raman spectroscopy.
DESIGN, TIME AND SETTING： A comparative observation was performed at the Key Laboratory of Excited States Physics in Chinese Academy of Science, Changchun Branch, from October 2004 to October 2005.
MATERIALS： JY-HR800 laser confocal micro-Raman spectrometer was purchased from Jobin-Yvon France; 2060-10 argon ion laser was purchased from Spectra-Physics, USA.
METHODS： A total of 32 New Zealand rabbits were selected and sacrificed. The roots of spinal nerves were exposed under an operating microscope, and the anterior and posterior roots, approximately 3-5 mm, were dissociated, and frozen as transverse sections of 30 μm thickness. The sections were examined by micro-Raman spectroscopy.
MAIN OUTCOME MEASURES： The specific spectral features of motor and sensory fascicles in the Raman spectra.
RESULTS： Sections of the same type of nerve fascicle showed reproducibility with similar spectral features. Significant differences in the spectral properties, such as the intensity and breadth of the peak, were found between motor and sensory fascicles in the frequency regions of 1 088, 1 276, 1 439, 1 579, and 1 659 cm^-1. With the peak intensity ratio of 1.06 （/1276//1439） as a standard, we could identify motor fascicles with a sensitivity of 88%, specificity of 94 %, positive predictive value of 93% and negative predictive value of 88%. In the range of 2 700-3 500 cm^-1, the half-peak width of the motor fascicles was narrow and sharp, while that of the sensory fascicles was relatively wider. A total of 91% of the peak features were in accordance with the identification standard.
CONCLUSION： Motor and sensory fascicles exhibit different characteristics in Raman spectra, which are constant and reliable. Therefore, it is an effective method to identify nerve fascicles according to the specific spectrum.     

Diagnosis of neuroblastoma and ganglioneuroma using Raman spectroscopy

Background

Raman spectroscopy has proven to be useful in studying premalignant and malignant lesions in adults. This is the first report to evaluate Raman spectroscopy in the diagnosis and classification of neuroblastoma in children.

Methods

A biopsy or resection of fresh tissue samples from normal adrenal glands, neuroblastomas, ganglioneuromas, nerve sheath tumors, and pheochromocytoma at our hospital were equally divided between routine histology and spectroscopic studies. At least 12 spectra were collected from different regions of each sample using a Renishaw Raman microscope. Raw spectra were processed to remove noise, florescence, and shot noise, and then analyzed using principle component analysis and discriminant function analysis.

Results

We collected 698 spectra from 16 neuroblastomas, 5 ganglioneuromas, 3 normal adrenal glands, 6 nerve sheath tumors, and 1 pheochromocytoma. Raman spectroscopy differentiated between normal adrenal gland, and neuroblastoma and ganglioneuroma with 100% sensitivity and 100% specificity. It correlated well with the Shimada histologic classification system with 100% sensitivity and 100% specificity. It was also able to differentiate neuroblastoma from nerve sheath tumors and pheochromocytoma with high sensitivity and specificity.

Conclusion

This technique can differentiate neuroblastoma from ganglioneuroma and other tumors. It has a potential as a noninvasive real-time diagnostic tool in classifying pediatric tumors.     

Quantifying low levels of polymorphic impurity in clopidogrel bisulphate by vibrational spectroscopy and chemometrics

Vibrational spectroscopic methods were developed for quantitative analysis of Form II of clopidogrel bisulphate in Form I and Form II polymorphic mixtures. Results show that both IR and Raman spectroscopy combined with chemometrics are suitable to quantify low levels of Form II in Form I, down to 2 and 3%, respectively, with less than 1% limit of detection. Different preprocessing and multivariate methods were applied for spectral processing and were compared to find the best chemometric model. Common problems of quantitative vibrational spectroscopy in the solid phase are discussed; and procedures appropriate to eliminate them are proposed.     

Reduction of Staphylococcus aureus and Pseudomonas aeruginosa colonisation on PVC through covalent surface attachment of fluorinated thiols

Objectives This study reports the development, characterisation and microbiological testing of surface‐modified polyvinylchloride (PVC) films for the purpose of reducing bacterial adherence. Methods Irreversible covalent surface modification was achieved via nucleophilic substitution of fluorinated thiol‐terminated compounds onto the polymer backbone. Four fluorinated modifiers, 2,3,5,6‐tetrafluorothiophenol (TFTP), 4‐(trifluoromethyl)thiophenol (TFMTP), 3,5‐bis(trifluoromethyl)benzenethiol (BTFMBT) and 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10‐heptadecafluoro‐decane‐1‐thiol (HDFDT), were investigated. Modification was confirmed using attenuated total reflectance infrared spectroscopy; Raman mapping demonstrated that modification was homogenous on the macroscopic scale. The influence of fluorination on surface hydrophobicity was studied by contact angle analysis. The effect on microbial adherence was examined using Pseudomonas aeruginosa and Staphylococcus aureus. Key findings The resultant changes in contact angle relative to control PVC ranged from ?4° to +14°. In all cases, adherence of P. aeruginosa and S. aureus was significantly reduced relative to control PVC, with adherence levels ranging from 62% and 51% for TFTP‐modified PVC to 32% and 7% for TFMTP‐modified PVC. Conclusions These results demonstrate an important method in reducing the incidence of bacterial infection in PVC medical devices without compromising mechanical properties.     

心律失常与心肌梗死患者红细胞异常的光镊拉曼光谱分析

目的利用激光光镊拉曼光谱系统,测定健康者、心律失常患者和心肌梗死患者红细胞的拉曼光谱。方法取新鲜静脉血样本,经洗涤、离心处理后分离出红细胞,用激光光镊拉曼系统采集其红细胞的拉曼光谱。结果与正常红细胞比较,心血管疾病患者红细胞的光镊拉曼光谱有较大的差异,红细胞的整体谱线偏弱;部分特征谱数发生位移。结论通过对红细胞的分离和捕获并测定其拉曼散射光谱,研究和分析红细胞的内容物及生物大分子的变化。进一步收集并建立心血管疾病的拉曼光谱数据库,为分子水平上探讨常见心血管疾病的类型及发病机制提供依据。     

振动光谱法研究黄芩苷固体分散体的分散性

目的:用拉曼和红外光谱法研究黄芩苷昔固体分散体的分散性,以期获得一种新的简单易行的检查固体分散体分散性的方法.方法:用溶剂法制备黄芩苷固体分散体,用显微共焦拉曼光谱仪、傅里叶变换红外光谱仪和X射线衍射仪分别采集黄芩苷、PVP K30,黄芩苷:PVP K30(1:6)的物理混合物及黄芩苷固体分散体的拉曼图谱、红外图谱和X射线衍射图谱并进行对比分析.结果:拉曼光谱法支持了采用X射线衍射法得到的药物在固体分散体中以无定形态存在的结果,从而确证了固体分散体中药物结晶态的消失.结论:拉曼光谱法快速、直接、对样品无损伤,是一种新的理想的检查固体分散体分散性的方法.     

Raman spectroscopy of coated pharmaceutical tablets and physical models for multivariate calibration to tablet coating thickness

Raman spectra of a set of coated pharmaceutical tablets were analyzed for the purpose of calibrating the spectra to tablet coating thickness. Acetaminophen tablets were coated with a hydroxypropylmethylcellulose/polyethylene glycol film coating whose thickness was varied from 0 to 6% weight gain. Coatings were also prepared with two concentrations of TiO2 at several film thicknesses. The resulting spectral data set was analyzed using several different multivariate calibration procedures. The procedures examined in this study included spectral correction followed by target factor analysis, spectral correction with baseline subtraction followed by principal component regression, and first derivative computation followed by principal component regression. The results demonstrate that target factor analysis is a viable method for calibration of Raman spectra to tablet coating thickness. Calibration based on derivative spectra resulted in linear correlation that was equal to that of the results of target factor analysis for coatings without TiO2. However, target factor analysis was found to be superior to other methods when TiO2 was present in the tablet coatings. The effect of sample fluorescence on each of these chemometric methods was also examined. It was found that when photobleaching of fluorescent impurities due to exposure to the Raman excitation source was controlled, the tablet coating thickness could be calibrated to the intensity of the fluorescence signal. The results also demonstrate that for the samples examined here, calibration by target factor analysis is insensitive to variation in fluorescent intensity when the tablet coating emission spectrum is included in the matrix of target vectors.