p53 mutations in basal cell carcinomas arising in routine users of sunscreens

Sun exposure histories were obtained from a series of patients age 35 or younger following diagnosis and removal of a basal cell carcinoma (BCC). The DNA was extracted from tumor biopsy samples derived from BCC of 10 patients who reported that they did not use sunscreens during youth (age 18 or younger) and 10 patients who routinely employed sunscreens during this age period. Exons 5-9 of the p53 gene were then amplified in three fragments from these samples using a nested polymerase chain reaction (PCR) approach and screened for mutations using an RNA heteroduplex assay. All PCR products displaying evidence of a mutation were sequenced. It was found that 6 of the 10 patients who were not routine sunscreen users displayed mutations in these p53 exons. All of the mutations were located at dipyrimidine sites, five of the six were C-->T transitions and one mutation was a tandem double mutation, consistent with a role for solar UVB in BCC formation. In contrast, only one p53 mutation was detected in the group of 10 patients who routinely employed sunscreens during childhood and adolescence. Hence, a significantly (P = 0.029) lower level of p53 mutations was detected in the BCC obtained from sunscreen users compared with tumors derived from nonusers. These findings suggest that the mechanisms involved in the etiology of skin carcinogenesis differ in sunscreen users compared with people who did not routinely employ sunscreens. These data are also indicative of a protective effect associated with sunscreen use against the formation of p53 mutations. It is possible that the patients who were diagnosed with BCC despite their use of sunscreens possessed a genetic susceptibility for skin cancer formation and developed BCC through a p53-independent pathway. Alternatively, solar UVA wavelengths, that were generally not blocked by the suncare products employed by the sunscreen users, may have played a significant role in BCC development through induction of a mutation(s) in an oncogene and/or a tumor suppressor gene, other than p53, for these patients.     

Transport processes in the sorption of colored ions by peat particles

A three-step model has been proposed for the adsorption of Astrazone Blue dye (Basic Blue 69) on peat. The initial rate of uptake of dye ions due to physical adsorption and chemisorption (ion exchange) has been correlated using a surface mass transfer coefficient. These coefficients have been determined and expressed in the dimensionless mass transfer form, Sh/Sc^0.33, as a function of agitation, initial dye concentration, peat particle size range, dye solution temperature, and mass of peat.     

State of the art and limitations of quantitative polymerase chain reaction

Consequential to the implementation of European Commission (EC) Regulation 1139/98, EC Regulation 49/2000, and EC Regulation 50/2000 has been the need to measure accurately the levels of the genetically modified (GM) species Roundup Ready Soya and Bt 176 Maize that are present in food. Analytical methods to detect and quantitate these transgenic species have received much attention particularly with respect to the deminimus threshold of 1% for their presence in materials derived from non-GM identity-preserved (IP) supplies. The relative advantages and limitations of threshold analysis by double-competitive polymerase chain reaction (PCR) and quantitative real-time PCR are discussed in their application to the quantitative analysis of processed foods. Consideration is also given to other factors involved in the analyses that affect the performance of quantitative procedures, and to the many uncertainties involved in the precision of a reported analytical result.     

Exact rotamer optimization for protein design

Computational methods play a central role in the rational design of novel proteins. The present work describes a new hybrid exact rotamer optimization (HERO) method that builds on previous dead-end elimination algorithms to yield dramatic performance enhancements. Measured on experimentally validated physical models, these improvements make it possible to perform previously intractable designs of entire protein core, surface, or boundary regions. Computational demonstrations include a full core design of the variable domains of the light and heavy chains of catalytic antibody 48G7 FAB with 74 residues and 10(128) conformations, a full core/boundary design of the beta1 domain of protein G with 25 residues and 10(53) conformations, and a full surface design of the beta1 domain of protein G with 27 residues and 10(60) conformations. In addition, a full sequence design of the beta1 domain of protein G is used to demonstrate the strong dependence of algorithm performance on the exact form of the potential function and the fidelity of the rotamer library. These results emphasize that search algorithm performance for protein design can only be meaningfully evaluated on physical models that have been subjected to experimental scrutiny. The new algorithm greatly facilitates ongoing efforts to engineer increasingly complex protein features.     

简易型离子选择电极-流动注射分析仪的研制及卤水中氯、溴和碘的连续测定

本文设计研制了简单实用的流通池,组装了简易型离子选择电极—流动注射分析仪,对体系的分析特点和影响因素进行了考察。此装置性能可靠,能满足简单流注分析的需要,并建立了卤水中Cl~-、Br~-和I~-的连续测定方法。     

Tetraethyl 4-(3-nitrophenyl)-2,3,5,6-pyridinetetracarboxylate

Reaction of 3-nitrobenzaldehyde with diethyl oxalacetate in the presence of piperidine acetate and then ammonium acetate/acetic acid gave a moderate yield of tetraethyl 1,4-dihydro-4-(3-nitrophenyl)-2,3,5,6-pyridinetetracarboxylate. This was oxidized with nitric acid to tetraethyl 4-(3-nitrophenyl)-2,3,5,6-pyridinetetracarhoxylate which was hydrolyzed and decarboxylated to give 4-(3-nitrophenyl)pyridine.     

Precipitation and recrystallization of uniform CuCl particles formed by aggregation of nanosize precursors

Uniform, spherical CuCl particles were obtained by mixing aqueous solutions of CuCl ₂ and ascorbic acid in the presence of polyvinylpyrrolidone (PVP) as dispersing agent. The size and the uniformity of the resulting particles depended on the volume ratio of the reactant solutions, their concentrations, the distribution of the stabilizers, and the mixing method. The single jet precipitation yielded large spheres of broad size distributions, while the particles obtained by the double jet technique were rather uniform in size. The final colloidal CuCl particles were formed by the aggregation of nanocrystals, initially generated in the system. Depending on the pH of the reaction mixture, these particles slowly change to large CuCl crystals on aging in the mother liquor.     

The loop expansion for the effective potential in theP(φ)2 quantum field theory

We study the loop expansion for the effective potential, defined as the Fenchel transform (convex conjugate) of the pressure in an external field, in theP()₂ quantum field theory. For values of the classical fielda for which the classical potentialU ₀(a)=P(a)+1/2m ² a ² equals its convex hull and has nonvanishing curvature we prove that the 1-PI loop expansion is asymptotic as 0. We also give an example of a double well classical potential for which the 1-PI loop expansion fails to be asymptotic, and find the true asymptotics.This paper is a condensed version of the author's Ph.D. thesis for the Department of Mathematics, University of British Columbia, Vancouver, B.C., Canada V6T 1Y4     

五配位Cu(Ⅰ)配合物[Cu(4′-Phtpy)(PPh_3)_2](BF_4)的合成、结构及光谱性质研究

由[Cu(MeCN)2 (PPh3)2 ](BF4 )和 4′ 苯基 2,2′:6′,2″ 三联吡啶(4′ Phtpy)在室温下反应,合成了一个新颖的具有光致发光性能的五配位配合物[Cu(4′ Phtpy)(PPh3)2 ](BF4 ).对配合物进行了X射线衍射结构表征,并进行了红外光谱、紫外可见光谱、荧光光谱等光谱学分析.晶体属单斜晶系,空间群Pn,晶胞参数:a =1 0 80 7(6)nm,b =1 0 943 (6)nm,c=2 1610(12 )nm,α =90°,β =10 2 785(10 )°,γ =90°,V =2 492(2 )nm3,Z =2,Dc=1 3 5 4g·cm-3.配合物中,Cu(Ⅰ)与 4′ Phtpy的 3个N,2个PPh3的P配位呈变形三角双锥型结构,其轴向由Cu键合联吡啶的末端 2个N所组成,赤道平面由联吡啶的中心N原子和 2个PPh3的P原子所组成     

Structural Characterization of Anhydroicaritin Glycosides Using ESI—FT—ICR Mass Spectrometry

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was used to determine the structures of anhydroicaritin glycosides by the MS/MS experiments of anhydroicaritin glycosides and their methylated derivatives,With high accuracy FT-ICR-MS provides much information about the structures of compounds ,FT-ICR-MS shows the great potential application in the structural characterization of unknown compounds.