Dimethylbenzanthracene tumorigenesis and aryl hydrocarbon hydroxylase in mouse skin: inhibition by 7,8-benzoflavone

Mouse skin contains aryl hydrocarbon hydroxylase which is highly inducible. The enzyme system is inhibited when 7,8-benzoflavone is added to homogenates of skin epidermis. 7,8-Benzoflavone also inhibits mouse skin tumorigenesis caused by repeated treatment with 9,10-dimethylbenzanthracene or by a single treatment with this chemical followed by weekly treatment with croton oil. These findings suggest that this enzyme system may be responsible for the activation of 9,10-dimethylbenzanthracene to its carcinogenic form.     

Binding of benzo[a]pyrene 7,8-diol-9,10-epoxides to DNA, RNA, and protein of mouse skin occurs with high stereoselectivity

The formation, stereostructure, and cellular reactions of the 7,8-diol-9,10-epoxide metabolites of the carcinogen benzo[a]pyrene have been examined after topical application of benzo[a]pyrene to the skin of mice. In this known target tissue, polymer adducts from diastereomeric diol epoxides, (+)-(7S, 8R, 9R, 10R) and (+)-(7R, 8S, 9R, 10R), were formed stereospecifically from their corresponding 7,8-dihydrodiols. Both diol epoxides bind with proteins, RNA, and DNA in vivo. For the nucleic acids, binding occurs preferentially at the 2-amino group of guanine in cellular RNA and DNA in vivo. Methods for establishing the structure of the cellular adducts as well as the possible biological implications of their formation are discussed.     

Concanavalin A in vivo: induction of hemorrhagic skin lesions (Arthus-like reactions) in mice

Concanavalin A injected into the skin of mice induced the formation of hemorrhagic Arthus-like lesions. No lesions resulted if concanavalin A was adsorbed with insoluble (a2)- macroglobulin or if mice were first treated with nitrogen mustard. The ability of concanavalin A, phytohemagglutinin, or pokeweed mitogen to induce skin lesions seemed to parallel their ability to precipitate serum proteins.     

Immunologic inhibition of ultraviolet radiation-induced tumor suppressor cell activity

Long-term exposure of C3H mice to ultraviolet radiation resulted in the formation of suppressor T cells that recognize ultraviolet radiation-induced regressor skin cancers as a class before the appearance of overt tumors. Administration of monoclonal antibodies to the product of the I-Jk subregion of the major histocompatibility complex or low doses of cyclophosphamide in vivo inhibited the development or activity of these cells. This activity of the monoclonal antibody was eliminated by adsorption on B10.BR (I-Jk) but not B10.D2 (I-Jd) splenocytes. These findings provide evidence that elements expressing the I-J determinant are important in regulating the host response prior to the overt development of ultraviolet radiation-induced skin cancers and suggest novel therapeutic approaches to malignancies or other diseases involving suppressor T cells in their pathogenesis.     

Histamine-mediated delayed permeability response after scald burn inhibited by cimetidine or cold-water treatment

Scald injury to one ear of the hairless mouse induced significant (P < .05) delayed edema formation in remote, uninjured skin. This remote edema formation was completely inhibited by immediate cold-water treatment of the scalded ear. Cold-water treatment significantly reduced histamine loss from the scalded ear, and the edema-inhibiting effect of the treatment could be mimicked by treating the animal prior to injury with the H2-histamine receptor antagonist cimetidine or a drug that causes histamine depletion. These observations suggest (i) that a histamine-mediated, delayed permeability response occurs after thermal injury that causes remote edema formation and (ii) that one mechanism of remote edema inhibition by cold-water treatment is the prevention of histamine release from thermally injured tissues.     

Mammary carcinoma: enzymatic block in disialoganglioside biosynthesis

The sialyl transferase of disialoganglioside formation is depressed in mammary tumors induced in the rat by 7,12-dimethylbenz[a]anthracene. Specific activities of other glycosyltransferases of the pathway ceramide to monosialo-ganglioside are unchanged or elevated so that the ganglioside GM(1) accumulates and higher gangliosides are depressed. These findings with a solid tumor are critical to an involvement of gangliosides in the cell-surface changes of tumorigenesis.     

3种金乡大蒜中营养活性成分的含量比较

[目的]检测3种金乡大蒜中营养成分和活性物质含量,从化学分子水平探讨不同品种的差异,对于优化种质资源、提升大蒜后期加工利用的品质和附加值具有指导作用。[方法]采用食品化学的常规方法并结合大型仪器检测,测定大蒜中营养成分和活性成分的含量。[结果]基本营养成分可溶性糖、粗脂肪、蛋白质含量,以金乡紫皮蒜最高,金乡白皮蒜次之,独头蒜最少;金乡紫皮蒜维生素C含量最高,独头蒜次之,金乡白皮蒜最少;金乡白皮蒜的过氧化氢酶(CAT)活性最高,紫皮蒜次之,独头蒜最差;锗和大蒜素DADS含量则是独头蒜最高。[结论]对于偏重营养成分的利用,金乡紫皮蒜有较大优势;而对于大蒜素和锗的特色保健功能利用,独头蒜有更大优势。     

近红外量子点表皮生长因子单克隆抗体荧光探针对金黄地鼠颊黏膜癌变过程的动态可视化荧光成像研究

目的 利用近红外量子点表皮生长因子单克隆抗体荧光探针对由9,10-二甲基1,2苯并蒽（9,10-dimethylen-1,2-benzanthracene,DMBA）诱导建立的金黄地鼠颊黏膜癌变过程进行动态可视化荧光成像研究。方法 （1）用0.5%DMBA丙酮液诱导建立金黄地鼠颊黏膜癌变各期模型;（2）将水溶性近红外荧光量子点（QD800）表面功能性的修饰藕连表皮生长因子受体单克隆抗体（EGFR mAb）后,形成具有靶向功能性的QD800-EGFR mAb荧光探针;（3）将QD800-EGFR mAb经金黄地鼠各期癌变模型尾静脉注射入血液循环系统以靶向适配原理显示其颊黏膜动态癌变过程荧光图像。结果 （1）QD800-EGFR mAb能够通过血液循环系统与金黄地鼠颊黏膜癌变细胞上的EGFR特异性的靶向适配并荧光显影;（2）QD800-EGFR mAb显示的荧光图像随着金黄地鼠颊黏膜癌变程度的加深而增强,且能准确地显示癌灶的形状及浸润深度。结论 QD800-EGFR mAb通过与口腔癌不同癌变阶段癌细胞表面的EGFR靶向性适配结合来显示个体化荧光图像,可能对以后临床研究口腔癌的发生发展及转移规律发挥巨大的影响。     

Vaccinia dermal infection and methylcholanthrene in cortisone-treated mice

Cortisone-treated mice were inoculated with vaccinia virus, and then five paintings of methylcholanthrene were applied over the site of inoculation. In 70 percent of the mice, tumors developed at the site of inoculation, and 35 percent of the mice, with and without skin tumors, also developed lymphomas. Identically treated control mice that were vacciniaimmune developed a significantly lower incidence (38 percent) of both skin tumors and lymphomas     

水杨酸与氯化钙单一及复配诱导对黄瓜幼苗耐热性的影响

以黄瓜为试材,采用叶面喷施的方法,研究了水杨酸（SA）和CaCl2单一及复配处理对热胁迫逆境下黄瓜幼苗的诱抗作用。结果表明,SA和CaCl2单一及复配处理黄瓜幼苗耐热性均有提高,其中SA处理的SOD、POD活性增幅最大,在高温处理3天时SOD、POD活性分别比对照提高42．7％、77．1％,并且MDA含量降低42．6％;CaCl2处理的CAT活性和脯氨酸含量骤增且显著高于其它处理,在处理3天时CAT活性和脯氨酸含量分别比对照提高49．2％、42．7％。SA与CaCl2复配处理的诱导效果虽优于对照,但显著低于SA和CaCl2的单一处理,表现出拮抗性。     

酶法提取猕猴桃皮和渣中果胶的工艺研究

[目的]去除猕猴桃皮和渣中的淀粉和蛋白质,提取并制备膳食食用果胶。[方法]通过单因素和正交试验设计,分别确定0.4%淀粉酶和0.4%胰蛋白酶提取猕猴桃皮和渣中果胶的适宜工艺条件。[结果]0.4%淀粉酶可有效去除猕猴桃皮和渣中的淀粉,其适宜工艺条件为：料液比1∶10.0,50℃下酶解60 min;0.4%胰蛋白酶可有效去除猕猴桃皮和渣中的蛋白质,其适宜工艺条件为：料液比1∶10.0,35℃下酶解60 min。在最佳工艺条件下,经离心、浓缩得到果胶,其中猕猴桃皮和渣中的果胶得率分别为3.10%和1.39%。[结论]通过改良酶法,建立了猕猴桃皮和渣中果胶提取的适宜工艺。     

Neoplastic transformation of rat thymic cells induced in vitro by Gross leukemia virus

Cultures of embryonal rat thymus infected initially with Gross leukemia virus have, at the present time, abundantly replicated infectious virus particles for 20 months. Cells from these cultures, after 3 months in vitro, displayed morphological changes and induced formation of tumors upon isotransplantation. The tumors were serially transplantable, and subsequent transplants continue to carry the initial Gross leukemia virus.     

Anti-idiotypic antibodies bear the internal image of a human tumor antigen

Goat antibodies to idiotypes (anti-idiotypic antibodies; Ab2) that recognize an idiotype associated with the combining site of a BALB/c mouse IgG2a monoclonal antibody (Ab1) to human gastric carcinoma were used to immunize BALB/c mice and rabbits. A monoclonal anti-anti-idiotypic antibody (Ab3) of IgG1 isotype was obtained after immunization of mice. The Ab3 and the Ab1 showed identical binding specificities and bound with similar avidities to the same tumor antigen. The induction of Ab1-like Ab3 by Ab2 was not restricted to mice, since Ab3 could also be induced in rabbits. Both the mouse- and the rabbit-derived Ab3 bound the same gastrointestinal cancer-associated antigen as Ab1. These findings indicate that Ab2 induced the formation of antigen-specific Ab3, probably because it bears the internal image of the tumor-associated antigen. This Ab2 may therefore have potential for modulating the immune response of cancer patients to their tumors.     

Observation of individual chemical reactions in solution

Discrete chemical reaction events occurring in solution have been observed by single photon detection of a bimolecular, chemiluminescent reaction. The reactants were generated from 9,10-diphenylanthracene in acetonitrile with potential pulses applied to an ultramicroelectrode. Electrogenerated radical ions of opposite sign react to yield the excited singlet state of the parent compound. The chemical reactions were restricted to a 20-femtoliter volume adjacent to the electrode by the use of rapid potential pulses. Individual chemical reaction events were stochastic and followed the Poisson distribution, and the interarrival time between successive reaction events was exponentially distributed.     

Accelerated healing of incisional wounds in rats induced by transforming growth factor-beta

The role of polypeptide growth factors in the processes of inflammation and repair was investigated by analyzing the influence of transforming growth factor-beta (TGF-beta), applied directly to linear incisions made through rat dorsal skin. A dose-dependent, direct stimulatory effect of a single application of TGF-beta on the breaking strength of healing incisional wounds was demonstrated. An increase in maximum wound strength of 220 percent of control was observed at 5 days; the healing rate was accelerated by approximately 3 days for at least 14 days after production of the wound and application of TGF-beta. These increases in wound strength were accompanied by an increased influx of mononuclear cells and fibroblasts and by marked increases in collagen deposition at the site of application of TGF-beta. TGF-beta is thus a potent pharmacologic agent that can accelerate wound healing in rats.     

Tumor etiology and chromosome pattern

Fibrosarcomas induced in Chinese hamsters and rats by Rous sarcomla virus and 7,12-dimethylbenz(a)anthracene are associated with nonrandom chromosome variation. Although histologically indistinguishable, the tumors induced by the virus or chemical in each host species are characterized by completely different karyotypic patterns.     

Isotope-edited NMR of cyclosporin A bound to cyclophilin: evidence for a trans 9,10 amide bond

The binding of a 13C-labeled cyclosporin A (CsA) analog to cyclophilin (peptidyl prolyl isomerase) was examined by means of isotope-edited nuclear magnetic resonance (NMR) techniques. A trans 9,10 peptide bond was adopted when CsA was bound to cyclophilin, in contrast to the cis 9,10 peptide bond found in the crystalline and solution conformations of CsA. Furthermore, nuclear Overhauser effects (NOEs) were observed between the zeta 3 and epsilon 3 protons of the methylleucine (MeLeu) residue at position 9 of CsA and tryptophan121 (Trp121) and phenylalanine (Phe) protons of cyclophilin, suggesting that the MeLeu9 residue of CsA interacts with cyclophilin. These results illustrate the power of isotope-edited NMR techniques for rapidly providing useful information about the conformations and active site environment of inhibitors bound to their target enzymes.     

Activation of a c-K-ras oncogene by somatic mutation in mouse lymphomas induced by gamma radiation

Mouse tumors induced by gamma radiation are a useful model system for oncogenesis. DNA from such tumors contains an activated K-ras oncogene that can transform NIH 3T3 cells. This report describes the cloning of a fragment of the mouse K-ras oncogene containing the first exon from both a transformant in rat-2 cells and the brain of the same mouse that developed the tumor. Hybrid constructs containing one of the two pieces were made and only the plasmid including the first exon from the transformant gave rise to foci in NIH 3T3 cells. There was only a single base difference (G----A) in the exonic sequence, which changed glycine to aspartic acid in the transformant. By use of a synthetic oligonucleotide the presence of the mutation was demonstrated in the original tumor, ruling out modifications during DNA-mediated gene transfer and indicating that the alteration was present in the thymic lymphoma but absent from other nonmalignant tissue. The results are compatible with gamma radiation being a source of point mutations.     

Adenovirus tumorigenesis: role of the viral genome in determining tumor morphology

Adenovirus type 12 transforms the fibroblastic BHK21 (baby hamster kidney) cell line into rounded or cuboidal cells that give rise in hamsters to undifferentiated small cell sarcomas indistinguishable from those induced in newborn hamsters by inoculation of the virus itself. In contrast. cells from this line transformed by polyoma virus retain their fibroblastic morphology and induce fibrosarcomas in hamsters. This suggests that the morphology of tumors induced by the adenovirus-transformed cells from this line may be determined by the viral genome and that such mechanism may also explain the remarkably uniform microscopic appearance which seems to characterize tumors induced in hamsters by direct inoculation of adenovirus type 12.