MRI增强扫描联合DWI检测在乳腺癌诊断中的应用

本文探究了MRI增强扫描(DCE-MRI)联合磁共振扩散加权成像(DWI)检测对乳腺癌的诊断效果。回顾性分析2015年8月~2017年8月本院收治的经手术病理证实的乳腺癌患者81例,术前均行DCE-MRI和DWI检查,根据数据绘制时间-信号强度曲线(TIC),并计算扩散系数(ADC)值。以病理结果为金标准,计算单一检测及联合检测的诊断准确率,并采用ROC分析ADC值诊断乳腺癌良/恶性的效能。结果显示,81例患者经手术病理诊断显示良性37例、恶性44例;DCE-MRI与DWI联合检测的敏感度与准确度显著高于单一检测(P<0.05);良、恶性病灶的TIC分型分布比较,差异具有统计学意义(P<0.05);恶性病灶ADC值较良性病灶低(P<0.05);ADC值诊断乳腺癌良/恶性最佳界限值为1.28×10-3 mm 2/s,灵敏度和特异度分别为86.5%和90.9%。因此,DCE-MRI与DWI联合检测可明显提高乳腺癌良/恶性病变诊断的准确度,为临床诊断提供可靠影像学依据。     

Synthesis of third‐order non‐linear optical polymers based on conjugated poly(heteroarylene methines)

A series of 10 new poly(heteroarylene methylenes) containing one pyrrole or thiophene ring alternating with a carbon atom in the main chain were synthesized and characterized. The polymers which were synthesized in the air were found to be partially dehydrogenated by the oxygen, that is, the bridge carbon atoms between pyrrole or thiophene rings were partially sp³ atoms and partially sp² atoms. However the polymers which were synthesized in the flowing nitrogen atmosphere were found to be deoxidized, that is the bridge atoms were sp³ atoms. The deoxidized polymers could be oxidatively dehydrogenated with tetrchlorobenzoquinone. These polymers are useful model systems to investigate the effect of conjugation length on the electronic and optical properties of conjugated polymers. Third‐order optical non‐linearities of the reulting polymers were studied by z‐scan techniques. The results show that the reulting polymers exhibited large third‐order optical non‐linear susceptibilities as large as 10^?8 esu. Copyright © 2004 John Wiley & Sons, Ltd.     

Theoretical Investigations of the Inclusion Processes of (4-tert-butylphenyl) (3-sulfonatophenyl) (phenyl) Phosphine in β-Cyclodextrin

Quantum mechanical calculations on the (4-tert-butylphenyl)(3-sulfonatophenyl) (phenyl) phosphine/-cyclodextrin inclusion complex werecarried out using semi-empirical calculations. Inclusion process pathways are describedand the most probable structures of the 1:1 complex are sought through a global potentialenergy scan. The calculations suggest that the most stable structure is obtained whenthe aromatic ring bearing the tert-butyl group is includedinto the hydrophobic cavity of the -cyclodextrin from theside of the primary hydroxyl groups.     

Screening for unknown synthetic steroids in human urine by liquid chromatography-tandem mass spectrometry

Chemically modified steroids (designer steroids), including tetrahydrogestrinone and norbolethone, pose a threat to the integrity of the sport community. These compounds have recently been detected in urine specimens from athletes, resulting in temporary or permanent suspension from amateur and/or professional competition. Triple quadrupole mass spectrometers enable doping control laboratories to screen for unknown, anabolic, androgenic steroids utilizing precursor ion scans. On the basis of common dissociation patterns of steroids with common structural features, characteristic product ions were selected to serve as diagnostic markers for previously unidentified drugs or drug metabolites in human urine samples. An assay was established to complement standard screening procedures. Urine specimens were enzymically hydrolyzed, partitioned into ether, concentrated, and analyzed by precursor ion scanning. Spectra from samples fortified with eight standard compounds (methyltestosterone, ethyltestosterone, 1-testosterone, gestrinone, dihydrogestrinone, tetrahydrogestrinone, norbolethone, and propyltrenbolone) and one deuterium-labeled analog (d(4)-tetrahydrogestrinone) at 50 ng/ml of urine, had precursor ion peaks other than those from common endogenous steroids. Subsequent product ion scan experiments on precursor ions of peaks of unknown origin provided structural identification of the unknown compounds.     

有机磷化合物的质谱研究(Ⅳ)——1,3,2-二氮磷杂环戊烷衍生物的电子轰击(EI)质谱

本文报道了9种新的含磷杂环化合物的电子轰击(EI)质谱。根据B/E,B~2/E联动扫描的亚稳离子测定和高分辨精确质量测量数据,着重讨论了该类化合物的基峰离子形成过程和分子内的几种重排反应;同时探讨了该类化合物的一般裂解机理和质谱特征。     

Scanning the beta-globin gene for mutations in large populations by denaturing capillary and gel electrophoresis

Separation of mutant from nonmutant DNA sequences of 100 bp may be accomplished by using defined denaturing conditions of chemical denaturant and/or elevated temperature during electrophoresis on either polyacrylamide slab gels (denaturing gradient gel electrophoresis, DGGE) or capillary gels (constant denaturant capillary electrophoresis, CDCE). In analysis of mutant directly from a polymerase chain reaction (PCR) product mixture, both have detection sensitivities of approximately 1%. CDCE that facilitates an intermediate mutant enrichment step permits detection of mutants at fractions as low as 2 x 10(-6). Here we report the successful application of both approaches to scan for mutations of the human beta-globin gene (HBB) in two human population samples of approximately 5000 persons in the HBB. Using DGGE, the coding region and flanking intronic splice sites of HBB were scanned in a population of 4949 Han Chinese individuals in pool sizes of 48 individual DNA samples. Four point mutations ranging in mutant frequency from 0.5 to 0.0002 were identified. Using CDCE with a mutant enrichment step, these same sequences were scanned in a population of 5028, predominantly African-American juveniles (<9 years) as a single pooled DNA sample. Three point mutations were identified ranging in mutant frequency from 0.13 to 0.0005. This study shows that both the DGGE/small pool and the CDCE/large pool approaches offer the means to define the fine structure map of genetic variation in large population samples, and with appropriately engineered facilities to provide high throughput, should be useful in pangenomic scans to discover genes carrying casual mutations for common diseases.     

快扫描循环伏安法及其在电化学中的应用

本文介绍了快扫描循环伏安法及其特点,对这一方法在电化学及电分析化学中的应用作了评述。     

Recent developments in multi-component synchronous fluorescence scan analysis

The ability to analyse complex multi-component mixtures without resorting to tedious separation procedures is extremely useful for routine analysis. Single-wavelength fluorescence measurement is limited in its ability to analyse complicated multi-component samples when they have severely overlapping emission and/or excitation spectra. This can be overcome by using synchronous fluorescence scan (SFS), where overlapping of spectra can be minimized. The selectivity of SFS can still be increased by taking derivative spectrum, applying different multivariate methods, selective fluorescence quenching, three-dimensional synchronous measurement or using some of these procedures in combination. Recent developments in various synchronous fluorescence methods for analysis of multi-component systems are discussed in this review.     

Influence on mass‐selective ion ejection of the phase difference between the drive r.f. and the axial modulation potentials

The phase difference between the drive r.f. and the axial modulation potential is known to influence significantly the mass shift, and all commercial ion trap mass spectrometers use a fixed value for this difference. However, although this important parameter is partly responsible for the good precision achievable today in most commercial ion traps, little discussion on the variation of the phase difference between the drive r.f. and the axial modulation potential has appeared in the literature. We present here an examination of the influence of a low‐level axial modulation potential superimposed by capacitive coupling between the electrodes. Low‐level axial modulation potentials are used for certain analytical scans such as reverse scan or slow scan speeds. Such low‐level potentials help to prevent deterioration of mass resolution due to, for example, the dissociation of the ions during their resonant ejection from the ion trap. Reverse and forward scans are used to illustrate the mass shift and change in resolution, caused by a change in the phase difference between the drive r.f. potential applied to the ring electrode and the axial modulation potential applied on an end‐cap electrode, in electrospray ionization mass spectra. Copyright © 2005 John Wiley & Sons, Ltd.     

Electron spin relaxation times and rapid scan EPR imaging of pH‐sensitive amino‐substituted trityl radicals

Carboxy‐substituted trityl (triarylmethyl) radicals are valuable in vivo probes because of their stability, narrow lines, and sensitivity of their spectroscopic properties to oxygen. Amino‐substituted trityl radicals have the potential to monitor pH in vivo, and the suitability for this application depends on spectral properties. Electron spin relaxation times T₁ and T₂ were measured at X‐band for the protonated and deprotonated forms of two amino‐substituted triarylmethyl radicals. Comparison with relaxation times for carboxy‐substituted triarylmethyl radicals shows that T₁ exhibits little dependence on protonation or the nature of the substituent, which makes it useful for measuring O₂ concentration, independent of pH. Insensitivity of T₁ to changes in substituents is consistent with the assignment of the dominant contribution to spin lattice relaxation as a local mode that involves primarily atoms in the carbon and sulfur core. Values of T₂ vary substantially with pH and the nature of the aryl group substituent, reflecting a range of dynamic processes. The narrow spectral widths for the amino‐substituted triarylmethyl radicals facilitate spectral‐spatial rapid scan electron paramagnetic resonance imaging, which was demonstrated with a phantom. The dependence of hyperfine splittings patterns on pH is revealed in spectral slices through the image. Copyright © 2014 John Wiley & Sons, Ltd.