Titanium Dioxide Nanoparticles As Guardian against Environmental Carcinogen Benzo[alpha]Pyrene

Polycyclic aromatic hydrocarbons (PAH), like Benzo[alpha]Pyrene (BaP) are known to cause a number of toxic manifestations including lung cancer. As Titanium dioxide Nanoparticles (TiO₂ NPs) have recently been shown to adsorb a number of PAHs from soil and water, we investigated whether TiO₂ NPs could provide protection against the BaP induced toxicity in biological system. A549 cells when co-exposed with BaP (25 µM, 50 µM and 75 µM) along with 0.1 µg/ml,0.5 µg/ml and 1 µg/ml of TiO₂ NPs, showed significant reduction in the toxic effects of BaP, as measured by Micronucleus Assay, MTT Assay and ROS Assay. In order to explore the mechanism of protection by TiO₂ NP against BaP, we performed in silico studies. BaP and other PAHs are known to enter the cell via aromatic hydrocarbon receptor (AHR). TiO₂ NP showed a much higher docking score with AHR (12074) as compared to the docking score of BaP with AHR (4600). This indicates a preferential binding of TiO₂ NP with the AHR, in case if both the TiO₂ NP and BaP are present. Further, we have done the docking of BaP with the TiO₂ NP bound AHR-complex (score 4710), and observed that BaP showed strong adsorption on TiO₂ NP itself, and not at its original binding site (at AHR). TiO₂ NPs thereby prevent the entry of BaP in to the cell via AHR and hence protect cells against the deleterious effects induced by BaP.     

The A1555G mitochondrial DNA mutation in Greek patients with non-syndromic, sensorineural hearing loss

Mitochondrial DNA mutations are undoubtedly a factor that contributes to sensorineural, non-syndromic deafness. One specific mutation, the A1555G, is associated with both aminoglycoside-induced and non-syndromic hearing impairment. The mutation is considered to be the most common of all mitochondrial DNA deafness-causing mutations but its frequency varies between different populations. Here we report on the first large screening of the A1555G mitochondrial DNA mutation in the Greek population. The aim of this study was to determine the frequency of the A1555G mutation in Greek sensorineural, non-syndromic deafness patients, with childhood onset. We screened 478 unrelated Greek patients with hearing loss of any degree and found two individuals harboring the A1555G mutation (0.42%). Both cases had been subjected to aminoglycosides. They were prelingual, familial and homoplasmic for the A1555G mutation. One of the cases was also found heterozygous for the frequent GJB2 35delG mutation, while the other case was negative. The A1555G mutation seems to be less common than in other European populations.     

Effects of irradiance and spectral quality on seedling development of two Southeast Asian Hopea species

 Seedling developmental responses to understory shade combine the effects of reductions in irradiance and changes in spectral quality. We studied the seedling development of two Southeast Asian dipterocarp trees in response to differences in irradiance (photosynthetic photon flux density, PPFD) and spectral quality (red to far-red ratio, R:FR). The two species, Hopea helferei and H. odorata, are taxonomically closely related but differ in their ecological requirements; H. helferei is more drought-tolerant and typically grows in more open habitats. Seedlings were grown in six different replicated shadehouse treatments varying in percentage of solar PPFD and R:FR. The two species differed in the influence of light variables on most seedling characters, particularly for final height, internode distance, branch/trunk internodes, stem length/mass, leaf area/stem length, petiole length, and growth/mol of photons received. Most of the characters in both taxa were primarily influenced by PPFD, but spectral quality also influenced some characters – more so for H. odorata. The latter species grew more rapidly, particularly in the low PPFD treatments, and its leaves were capable of higher photosynthesis rates. However, growth in H. helferei was not reduced in direct sunlight. The growth of this taxon may be constrained by adaptations, particularly in leaves, for drought tolerance. Received: 14 April 1996 / Accepted: 8 October 1996     

High Resolution T1ρ Mapping of In Vivo Human Knee Cartilage at 7T

Purpose

Spin lattice relaxation time in rotating frame (T1ρ) mapping of human knee cartilage has shown promise in detecting biochemical changes during osteoarthritis. Due to higher field strength, MRI at 7T has advantages in term of SNR compared to clinical MR scanners and this can be used to increase in image resolution. Objective of current study was to evaluate the feasibility of high resolution T1ρ mapping of in vivo human knee cartilage at 7T MR scanner.

Materials and Methods

In this study we have used a T1ρ prepared GRE pulse sequence for obtaining high resolution (in plan resolution  = 0.2 mm²) T1ρ MRI of human knee cartilage at 7T. The effect of a global and localized reference frequency and reference voltage setting on B₀, B₁ and T1ρ maps in cartilage was evaluated. Test-retest reliability results of T1ρ values from asymptomatic subjects as well as T1ρ maps from abnormal cartilage of two human subjects are presented. These results are compared with T1ρ MRI data obtained from 3T.

Results

Our approach enabled acquisition of 3D-T1ρ data within allowed SAR limits at 7T. SNR of cartilage on T1ρ weighted images was greater than 90. Off-resonance effects present in the cartilage B₀, B₁ and T1ρ maps obtained using global shim and reference frequency and voltage setting, were reduced by the proposed localized reference frequency and voltage setting. T1ρ values of cartilage obtained with the localized approach were reproducible. Abnormal knee cartilage showed elevated T1ρ values in affected regions. T1ρ values at 7T were significantly lower (p<0.05) compared to those obtained at 3T.

Conclusion

In summary, by using proposed localized frequency and voltage setting approach, high-resolution 3D-T1ρ maps of in vivo human knee cartilage can be obtained in clinically acceptable scan times (<30 min) and SAR constraints, which provides the ability to characterize cartilage molecular integrity.     

B 超引导下子宫内膜消融术治疗更年期功血51 例临床分析

目的:探讨在B超引导下子宫内膜消融术治疗更年期功血的效果。方法:扩张宫颈至6.5号,吸宫,在B超监视下由子宫右前壁始向外刮凝,依次顺时针方向刮凝宫腔2周。结果:治愈31例(60.8%),有效19例(37.3%),好转1例(1.9%),无效0例。结论:电凝刀子宫内膜消融术与其他更年期功血治疗方法相比,消融的范围及深度由B超监视,安全性高,创伤小,不开刀,恢复快,并且治愈率高,更容易在临床上推广。     

PCR反应混合液的冻干处理及其应用

本研究将除模板DNA以外的PCR反应混合液,经过真空浓缩冻成干粉状后,分别置于室温和4℃贮存,经过一定的贮藏时间后进行PCR反应,发现经冻干处理的样品能在较长的贮存时间内保持扩增活性,这将给实际工作带来很大的便利。Abstract:In this paper we introduce a new storage method of PCR ingredient.PCR mixture except DNA template has been frozen to dry powder by the DNA-Plus system.This kind of powder was stored at room temperature or 4℃.PCR has been run in different period of storage.It was discovered that the samples of lyophilization could keep activity for a long time.     

Conformational transition between native and reactive center cleaved forms of alpha 1-antitrypsin by Fourier transform infrared spectroscopy and small-angle neutron scattering

alpha 1-Antitrypsin (alpha 1-AT) is the best-characterized member of the serpin superfamily of plasma proteins. Protease inhibitor members of this family undergo a characteristic reactive-center cleavage during expression of their inhibitory activity. The physical basis of this transition in alpha 1-AT from the stressed native conformation to the more stable reactive center cleaved (split) form was studied by Fourier transform infrared (FT-IR) spectroscopy and neutron scattering. The FT-IR spectra show that, while split alpha 1-AT has three intense well-resolved components associated with the presence of antiparallel beta-sheet and alpha-helix conformations, the amide I band of native alpha 1-AT has only one intense component, associated with the presence of beta-sheet structure. 1H-2H exchange within the polypeptide backbone, studied by FT-IR and NMR spectroscopy, shows that the native form undergoes greater exchange than the split form. Under the same conditions, neutron scattering shows no differences in the radius of gyration RG of the native and the split forms. In contrast, in high concentrations of phosphate approaching those used for crystallization, the native form (unlike the split form) undergoes dimerization. These data indicate that the conformational transition largely involves localized secondary and tertiary structure rearrangements. We propose that the energetically stressed native alpha 1-AT structure is the consequence of a significantly reduced number of hydrogen bonds in secondary structure components and that reactive-site cleavage between Met358 and Ser359 is the key for the development of the fully hydrogen bonded more stable serpin structure.     

微生物学开放性实验激发学生的创新能力

针对微生物学实验教学中存在的问题,如未突出以学生为中心的理念、难以培养学生的创新性思维、无法激发学生学习的积极性、考核无法反应学生的真实水平等,我们开展了以学生兴趣为前提、学生主动参与为抓手、提高学生创新能力为目标的系列微生物学相关开放性创新实验。采用三段式教学设计,通过文献调研、开展实验和结果总结构建了综合考核方案,达成了微生物学实验的教学目标,丰富了与理论教学紧密联系的\"基础、综合、创新\"系列化、多层次、阶梯状的专业实践教学体系。开放性创新实验项目的实施,推动了学生学习研究、科研训练和项目实践,提高了学生科创竞赛的参赛水平。开放实验也对授课教师的科研素养和教学能力有了更高的要求,做好实验室的管理,进而保障开放实验项目的顺利施行。