Comparative mouse skin tumorigenicity and induction of Ha-ras mutations by bay region diol epoxides of 5-methylchrysene and 5,6- dimethylchrysene

We compared the tumor-initiating activities toward mouse skin of two structurally related polycyclic aromatic hydrocarbon diol epoxides: racemic anti-1,2,3,4-tetrahydro-5,6-dimethylchrysene-1,2-diol-3,4- epoxide (5,6-diMeCDE) and racemic anti-1,2,3,4-tetrahydro-5- methylchrysene-1,2-diol-3,4-epoxide (5-MeCDE). Tumors induced by these diol epoxides were analysed for mutations in the Ha-ras gene. 5,6- diMeCDE is derived from the non-planar parent compound 5,6- dimethylchrysene, and reacts to approximately equal extents with dA and dG in DNA, whereas 5-MeCDE is derived from a nearly planar parent compound, 5-methylchrysene, and reacts mainly with dG in DNA. 5,6- diMeCDE, at initiating doses of 33, 100 or 400 nmol per mouse, induced 1.2, 2.2 and 6.2 skin tumors per mouse, respectively. It was significantly less tumorigenic than 5-MeCDE which induced 3.1, 7.5 and 9.1 skin tumors per mouse at the same doses. Tumors induced by 5,6- diMeCDE had a large number of CAA-->CTA mutations in codon 61 of the Ha- ras gene: 50, 55 and 75% of the tumors analysed had this mutation at the 33, 100 and 400 nmol doses. No mutations were found in codons 12 and 13 in the tumors induced by 5,6-diMeCDE. In contrast, CAA-->CTA mutations in codon 61 were rarely seen in tumors induced by 5-MeCDE. At the highest dose of 5-MeCDE, 20% of the tumors analysed had mutations at G of codons 12 and 13. The results of this comparative study support the hypothesis that mutations in the Ha-ras gene in mouse skin tumors induced by PAH diol epoxides occur as a result of their direct reaction with the gene. However, pathways other than the commonly observed Ha- ras codon 61 mutations are clearly important in mouse skin tumorigenesis by these diol epoxides.      

Noninvasive in vivo magnetic resonance imaging of injury-induced neointima formation in the carotid artery of the apolipoprotein-E null mouse

Mice deficient in apolipoprotein-E (apoE) experience severe hypercholesterolemia, are prone to atherosclerosis, and recently have emerged as a powerful tool in the study of plaque formation. In this study, we developed magnetic resonance (MR) imaging methods to detect the progression of atherosclerosis noninvasively in a mouse model of arterial injury. Four 14-week-old apoE-deficient mice were imaged 5 weeks after beginning an atherogenic Western diet and 4 weeks after wire denudation injury of the left common carotid artery (LCCA). Information from several images was combined into high-information content images using methods previously developed. The image resolution was 47 x 47 x 750 microm(3). We acquired T1-, T2-, and proton density (PD)-weighted images (TR/TE 650/14, 2000/60, and 2000/14 msec, respectively). Each 8-bit image was placed in a separate color channel to produce a 24-bit color image (red = T1, green = PD, and blue = T2). The composite image created contrast between different tissue types that was superior to that of any single image and revealed significant luminal narrowing of the LCCA, but not the uninjured RCCA. MR images were compared with corresponding histopathology cross sections and luminal area measurements from each method correlated(r2= 0.61). Atherosclerotic luminal narrowing was successfully detected through MR imaging in a mouse model of arterial injury that is small, reproduces quickly, and lends itself to genetic analysis and manipulation.     

白首乌化学成分的研究

自白首乌主要品种耳叶牛皮消(Cynanchum auriculatum Royle ex Wight)根中首次分得三个已知甾体酯型甙元:告达亭(caudatin),开德甙元(kidjolanin),萝藦甙元(Metaplexigenin)和一种新的二苯酮衍生物(Ⅳ),经光谱分析推定其结构为2,6,2′,5′-四羟基,3-乙酰基,6′-甲基二苯酮,命名白首乌二苯酮。     

Influence of Xenogeneic and Alloplastic Carriers for Bone Augmentation on Human Unrestricted Somatic Stem Cells

Alloplastic and xenogeneic bone grafting materials are frequently used for bone augmentation. The effect of these materials on precursor cells for bone augmentation is yet to be determined. The aim of this study was to ascertain, in vitro, how augmentation materials influence the growth rates and viability of human unrestricted somatic stem cells. The biocompatibility of two xenogeneic and one alloplastic bone graft was tested using human unrestricted somatic stem cells (USSCs). Proliferation, growth, survival and attachment of unrestricted somatic stem cells were monitored after 24 h, 48 h and 7 days. Furthermore, cell shape and morphology were evaluated by SEM. Scaffolds were assessed for their physical properties by Micro-CT imaging. USSCs showed distinct proliferation on the different carriers. Greatest proliferation was observed on the xenogeneic carriers along with improved viability of the cells. Pore sizes of the scaffolds varied significantly, with the xenogeneic materials providing greater pore sizes than the synthetic inorganic material. Unrestricted somatic stem cells in combination with a bovine collagenous bone block seem to be very compatible. A scaffold’s surface morphology, pore size and bioactive characteristics influence the proliferation, attachment and viability of USSCs.     

白首乌化学成分的研究

自白首乌主要品种耳叶牛皮消(Cynanchum auriculatum Royle ex Wight)根中首次分得三个已知甾体酯型甙元:告达亭(caudatin),开德甙元(kidjolanin),萝藦甙元(Metaplexigenin)和一种新的二苯酮衍生物(Ⅳ),经光谱分析推定其结构为2,6,2′,5′-四羟基,3-乙酰基,6′-甲基二苯酮,命名白首乌二苯酮。     

用差示扫描量热法及激光拉曼光谱研究足叶乙甙对二棕榈酰磷脂酰胆碱脂质体膜流动性影响

本文用DSC和激光拉曼光谱研究抗癌药物足叶乙甙(4-去甲基表鬼臼毒素-β-D-乙叉吡喃葡萄糖甙,简称VP 16-213)与二棕榈酰磷脂酰胆碱(DPPC)脂质体的作用。VP 16-213分子掺入DPPC脂质体双层中,不但使相转变温度向高温移动,而且吸热峰的半高宽度随VP 16-213浓度增加而变宽。其Raman光谱在频率2850 cm~(-1)处的C-H键对称伸缩振动亦随着药物浓度增加而减弱。这些结果表明VP 16-213分子是定域在脂双层中DPPC分子链的C_1～C_9亚甲基区域,使脂质体的有序性提高而流动性降低。     

Purified murine hematopoietic stem cells function longer on nonirradiated W41/Wv than on +/+ irradiated stroma

Mouse bone marrow (BM) was separated into low-density, lineage- negative, wheat germ agglutinin-positive (WGA+), Rhodamine-123 bright (Rhbright) or dim (Rhdim) cells to obtain populations that were highly enriched for committed progenitors (Rhbright cells) or for more primitive stem cells (Rhdim). When 2,500 Rhbright or Rhdim cells were seeded onto 6-week-old irradiated (20 Gy) long-term BM cultures (LTBMC), the nonadherent cell production from Rhbright cells was transient and ended after 5 weeks. Production from Rhdim cells did not begin until week 3, peaked at week 5, and ended at week 8, when the irradiated stroma seemed to fail. Termination of cell production from Rhdim cells did not occur in nonirradiated LTBMC from W41/Wv mice. During peak nonadherent cell production, 25% to 30% of the cells in the nonirradiated LTBMC from W41/Wv mice had donor cell markers. Two approaches were tested to try to enhance the proportion or number of donor cells. Addition of Origen-HGF at the time of seeding Rhdim cells caused a nonspecific increase in both host and donor cell production, but a specific increase in production of donor cells was obtained by seeding the cultures at 2 weeks rather than 6 weeks. Limiting dilution of Rhdim cells gave the same frequency of wells producing cells on both irradiated +/+ and nonirradiated W41/Wv or W/Wv cultures.