Er:YAG激光桩道预处理的研究进展

本文回顾了Er:YAG激光活化根管冲洗技术的最新研究进展,包括光子诱导光声流(photon initiated photoacoustic streaming,PIPS)技术和冲击波增强发射光声流(shock wave enhanced emission photoacoustic streaming,SWEEPS)技术,探讨Er:YAG激光预处理桩道的原理、优点以及对纤维桩粘接强度的影响,以期为临床选择适宜的桩道处理方法提供新思路。     

Diallyl disulfide and diallyl trisulfide in garlic as novel therapeutic agents to overcome drug resistance in breast cancer

Breast cancer is one of the leading causes of cancer-related deaths in women worldwide. It is a cancer that originates from the mammary ducts and involves mutations in multiple genes. Recently, the treatment of breast cancer has become increasingly challenging owing to the increase in tumor heterogeneity and aggressiveness, which gives rise to therapeutic resistance. Epidemiological, population-based, and hospital-based case-control studies have demonstrated an association between high intake of certain Allium vegetables and a reduced risk in the development of breast cancer. Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are the main allyl sulfur compounds present in garlic, and are known to exhibit anticancer activity as they interfere with breast cancer cell proliferation, tumor metastasis, and angiogenesis. The present review highlights multidrug resistance mechanisms and their signaling pathways in breast cancer. This review discusses the potential anticancer activities of DADS and DATS, with emphasis on drug resistance in triple-negative breast cancer (TNBC). Understanding the anticancer activities of DADS and DATS provides insights into their potential in targeting drug resistance mechanisms of TNBC, especially in clinical studies.     

A perivascular niche in the bone marrow hosts quiescent and proliferating tumorigenic colorectal cancer cells

Disseminated tumor cells (dTCs) can frequently be detected in the bone marrow (BM) of colorectal cancer (CRC) patients, raising the possibility that the BM serves as a reservoir for metastatic tumor cells. Identification of dTCs in BM aspirates harbors the potential of assessing therapeutic outcome and directing therapy intensity with limited risk and effort. Still, the functional and prognostic relevance of dTCs is not fully established. We have previously shown that CRC cell clones can be traced to the BM of mice carrying patient-derived xenografts. However, cellular interactions, proliferative state and tumorigenicity of dTCs remain largely unknown. Here, we applied a coculture system modeling the microvascular niche and used immunofluorescence imaging of the murine BM to show that primary CRC cells migrate toward endothelial tubes. dTCs in the BM were rare, but detectable in mice with xenografts from most patient samples (8/10) predominantly at perivascular sites. Comparable to primary tumors, a substantial fraction of proliferating dTCs was detected in the BM. However, most dTCs were found as isolated cells, indicating that dividing dTCs rather separate than aggregate to metastatic clones—a phenomenon frequently observed in the microvascular niche model. Clonal tracking identified subsets of self-renewing tumor-initiating cells in the BM that formed tumors out of BM transplants, including one subset that did not drive primary tumor growth. Our results indicate an important role of the perivascular BM niche for CRC cell dissemination and show that dTCs can be a potential source for tumor relapse and tumor heterogeneity.     

去势后大鼠海马结构一氧化氮合酶阳性神经元的变化

目的：观察去势后大鼠海马结构一氧化氮合酶（NOS）阳性神经元的变化。方法：用黄递酶组织化学染色方法观察切除双侧卵巢后雌后SD大鼠海马结构NOS阳性神经元的形态，分布的变化，并进行计算机图像分析。结果：去势后海马结构NOS阳性神经元分布变化有区域差异性；NOS阳性神经元在下托、海马（CA）一区邻近下托的部分、CA三区、CA四区（CA4）和齿状回（DG）数目明显减少，而在CA二区数目明显明显增多，CA4和DG的NOS阳性神经元平均密度降低，胞体的平均周长和平均截面积都明显减少。结论：雌激素可能通过影响海马结构NOS的表达来影响学习和记忆。     

Development of the blood-testis barrier in the domestic fowl (Gallus domesticus)

The formation of the blood-testis barrier (BTB) in the domestic fowl was studied at the electronmicroscopic level employing lanthanum as a tracer. No effective barrier could be demonstrated in testes before puberty, although several components of the Sertoli junctional complex such as focal tight junctions and desmosomes were already existent. The time of onset of meiosis after hatching showed great individual variation and meiosis did not occur synchronously in the tubules of a given testis. An effective barrier could first be detected in tubules containing early spermatids, and in which spermatogonia and primary spermatocytes at the leptotene stage were still within the open compartment. Thus, barrier formation was correlated with the occurrence of haploid germ cells. Complete compartmentation of seminiferous tubules, leaving only spermatogonia within the open compartment, was attained in tubules containing elongated spermatids of the maturation phase. In these tubules, primary spermatocytes at the leptotene stage were situated in an intermediate compartment.     

Growth cones and axon trajectories of a sensory pathway in the amphibian spinal cord

Central axons of sensory ganglion (SG) neurons of the Xenopus tail enter the spinal cord via the ventral roots and travel dorsally and rostrally following a diagonal course within the lateral marginal zone (LMZ) to reach the dorsolateral fasciculus (DLF) (Nordlander et al.: Brain Res., 440:391-395, 1988). Axons are dispersed as they cross the cord. At the DLF they turn and travel together rostrally, sharing the fascicle with axons of primary sensory neurons (Rohon-Beard cells) already present in the tract. In this paper we analyze the growth patterns of the central projections of SG axons in the tail by using HRP applied to proximal branches of tail spinal nerves. Growth cones of the diagonal route are variable in configuration, often bearing processes that spread within the LMZ. Once the DLF, growth cones change shape, becoming distinctly linear. While growth cones navigating the diagonal part of the route never contact or fasciculate with other diagonal SG axons, SG growth cones and axons of the DLF are more closely associated with their fellows. Measurements of the slopes of SG axons in the diagonal route indicated a limited range with a mean of 23 degrees with respect to the cord axis. On the basis of these observations, we conclude that 1) navigational patterns for growth cones of this pathway differ for the diagonal versus the DLF part of its course, and 2) fasciculation is not a mechanism used by SG axons to reach the DLF, but that instead, each axon is able to find its way independently.     

Preparation of protected peptidyl thioester intermediates for native chemical ligation by Nα‐9‐fluorenylmethoxycarbonyl (Fmoc) chemistry: considerations of side‐chain and backbone anchoring strategies,and compatible protection for N‐terminal cysteine*,†

Abstract: Native chemical ligation has proven to be a powerful method for the synthesis of small proteins and the semisynthesis of larger ones. The essential synthetic intermediates, which are C‐terminal peptide thioesters, cannot survive the repetitive piperidine deprotection steps of N^α‐9‐fluorenylmethoxycarbonyl (Fmoc) chemistry. Therefore, peptide scientists who prefer to not use N^α‐t‐butyloxycarbonyl (Boc) chemistry need to adopt more esoteric strategies and tactics in order to integrate ligation approaches with Fmoc chemistry. In the present work, side‐chain and backbone anchoring strategies have been used to prepare the required suitably (partially) protected and/or activated peptide intermediates spanning the length of bovine pancreatic trypsin inhibitor (BPTI). Three separate strategies for managing the critical N‐terminal cysteine residue have been developed: (i) incorporation of N^α‐9‐fluorenylmethoxycarbonyl‐S‐(N‐methyl‐N‐phenylcarbamoyl)sulfenylcysteine [Fmoc‐Cys(Snm)‐OH], allowing creation of an otherwise fully protected resin‐bound intermediate with N‐terminal free Cys; (ii) incorporation of N^α‐9‐fluorenylmethoxycarbonyl‐S‐triphenylmethylcysteine [Fmoc‐Cys(Trt)‐OH], generating a stable Fmoc‐Cys(H)‐peptide upon acidolytic cleavage; and (iii) incorporation of N^α‐t‐butyloxycarbonyl‐S‐fluorenylmethylcysteine [Boc‐Cys(Fm)‐OH], generating a stable H‐Cys(Fm)‐peptide upon cleavage. In separate stages of these strategies, thioesters are established at the C‐termini by selective deprotection and coupling steps carried out while peptides remain bound to the supports. Pilot native chemical ligations were pursued directly on‐resin, as well as in solution after cleavage/purification.     

Angular bundle kindling is accelerated in rats with a genetic predisposition to acoustic stimulus-induced seizures

Limbic kindling was examined in genetically epilepsy-prone (GEPR) and non-epileptic control rats. The early stage of kindling development was accelerated in both groups of GEPR rats compared to controls. Later stages of kindling were accelerated in GEPR-9 but not GEPR-3 rats. These results indicate that GEPR rats have an enhanced susceptibility to limbic kindling and suggest that limbic brain alterations may contribute to acceleration of the early stage kindling development in GEPR rats.     

加减大黄廑虫丸抑制血管生成的实验研究

目的探讨加减大黄廑虫丸对血管生成的抑制作用。方法鸡胚绒毛尿囊膜（CAM）法检测加减大黄磨虫丸对血管生成的影响；采用MTS比色法观察不同浓度的加减大黄磨虫丸对血管内皮生长因子（VEGF）诱导的ECV-504细胞增殖的影响；Tran—swell小室检测不同浓度的加减大黄廑虫丸对ECV-304细胞移行的影响；Matrigel实验检测不同浓度的加减大黄磨虫丸对ECV-304细胞内皮管腔形成的影响。结果加减大黄磨虫丸中、低浓度组能够抑制鸡胚CAM血管生成；MTS比色法显示，0．05—0．20g/ml浓度的加减大黄鹰虫丸对VEGF诱导的ECV-304细胞增殖具有抑制作用，而更低和更高浓度的加减大黄廑虫丸则无抑制作用。Transwell小室实验显示，加减大黄廑虫丸浓度为0、12．5、25．0和50．0mg/ml时ECV-504细胞移行数分别为208．67±17．16、132．67±16．50、78．33±13．50和18．67±6．66；Matrigel实验显示，加减大黄磨虫丸浓度为0、12．5、25．0和50．0mg/ml时ECV-304细胞内皮管腔形成数分别为25．67±1．53、22．33±1．53、16．33±2．52和2．33±1．53，可见抑制细胞移行和管腔形成的作用随浓度增大而增强。结论加减大黄廑虫丸具有明显抑制血管生成的作用。