Vacuum ultraviolet circular dichroism of poly(galacturonic acid), sodium polygalacturonate and calcium polygalacturonate

Vacuum ultraviolet circular dichroism spectra are reported for poly(galacturonic acid) solution and film, sodium polygalacturonate solution and film, and calcium polygalacturonate gel. In addition to the positive c.d. band near 208 nm previously observed, we find a pair of higher energy bands at 170 180 nm (negative) and 145 nm (positive). The low energy band, assigned to an $\text{n-π}{}^1$ carboxyl transition, is blue-shifted upon gelation or film formation.     

免疫细胞浸润在非小细胞肺癌诊断与预后中的应用

免疫细胞浸润对癌症的诊断与预后有着重要意义。文中收集TCGA数据库已收录的非小细胞肺癌肿瘤与正常组织基因表达数据,利用CIBERSORT工具得到22种免疫细胞占比来评估免疫细胞浸润情况。以22种免疫细胞占比为特征,用机器学习方法构建了非小细胞肺癌肿瘤与正常组织的分类模型,其中随机森林方法构建的模型分类效果AUC=0.987、敏感性0.98及特异性0.84。并且用随机森林方法构建的肺腺癌和肺鳞癌肿瘤组织分类模型效果AUC=0.827、敏感性0.75及特异性0.77。用LASSO回归筛选22种免疫细胞特征,保留8种强相关特征组成的免疫细胞评分结合临床特征构建了非小细胞肺癌预后模型。经评估及验证,预后模型C-index=0.71并且3年和5年的校准曲线拟合良好,可以对预后风险度进行准确预测。本研究基于免疫细胞浸润所构建的分类模型与预后模型,旨在对非小细胞肺癌的诊断与预后研究提供新的策略。     

The role of YTH domain containing 2 in epigenetic modification and immune infiltration of pan-cancer

YTH domain containing 2 (YTHDC2) is the largest N6-Methyladenosine (m⁶A) binding protein of the YTH protein family and the only member containing ATP-dependent RNA helicase activity. For further analysing its biological role in epigenetic modification, we comprehensively explored YTHDC2 from gene expression, genetic alteration, protein-protein interaction (PPI) network, immune infiltration, diagnostic value and prognostic value in pan-cancer, using a series of databases and bioinformatic tools. We found that YTHDC2 with Missense mutation could cause a different prognosis in uterine corpus endometrial carcinoma (UCEC), and its different methylation level could lead to a totally various prognosis in adrenocortical carcinoma (ACC), cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), lung squamous cell carcinoma (LUSC) and UCEC. The main molecular mechanisms of YTHDC2 focused on catalytic activity, helicase activity, snRNA binding, spliceosome and mRNA surveillance. Additionally, YTHDC2 was notably correlated with tumour immune infiltration. Moreover, YTHDC2 had a high diagnostic value for seven cancer types and a prognostic value for brain lower grade glioma (LGG), rectum adenocarcinoma (READ) and skin cutaneous melanoma (SKCM). Collectively, YTHDC2 plays a significant role in epigenetic modification and immune infiltration and maybe a potential biomarker for diagnosis and prognosis in certain cancers.     

真空渗入转化法中农杆菌在植株体内的分布和活力变化

以真空渗入处理后的白菜植株为材料,采用组织化学染色法和细菌平板培养的方法,研究了农杆菌在植株体内的分布特点及其活力变化。结果表明：不同器官中农杆菌的分布量不同,以花器官中分布最多,叶中次之,茎中最少;农杆菌存在于细胞间隙中,维管束及其周围分布较集中,在胚珠中大量分布。处理后植株体内,各器官中农杆菌的生活力及其数量都随时间延长而减少,但是花器官中的农杆菌存活量较大,处理15d后的花蕾中仍然有一定量(约10.3个CFU/g组织)具有活力的农杆菌存在。讨论了这些研究结果在揭示真空渗入转化法的转化过程和提高转化频率中的意义。     

From Demographic Strategies to Mathematical Models: Trends in Population Dynamics Studies of Aquatic Oligochaeta

The existence of a negative relationship between fine sediment infiltration during the incubation period and salmonid embryo survival has often been discussed in the literature. However, few studies have specifically addressed this relationship in the field. We conducted a field experiment to examine the relationship between survival of Atlantic salmon (Salmo salar) embryos contained in incubation baskets and the patterns of fine sediment infiltration into the baskets during the incubation period. The results indicate that survival to pre-eyed (STPE), eyed (STE) and hatched (STH) stages of development were all negatively correlated with the percentage of fine sediment entering the baskets. STPE and STE were most strongly affected by silts and clays (<0.063 mm) although this size class represented only a small fraction of the grain size distribution inside the incubation baskets (0.03–0.41%). STH was most strongly correlated with the infiltration of medium sand (0.25–0.50 mm) material. On average, 66% of the implanted embryos survived to the pre-eyed stage of development compared to 63% for the eyed and 48% for the hatched stages of development.     

不同护坡草本植物的根系特征及对土壤渗透性的影响

为明确三峡库区植被边坡植物物种根系特征与土壤渗透性之间的关系,以裸地为对照,应用WinRHIZO(Pro.2004c)根系分析系统对香根草(Vetiveria zizanioides(Lin.) Nash)、百喜草(Paspalum notatum Flugge)、狗牙根(Cynodon dactylon (L) Pers.)和紫花苜蓿(Medicago sativa L.)等4种护坡草本的根系特征进行定量分析.结果表明:(1)紫花苜蓿和香根草的根长密度和根表面积密度显著大于狗牙根和百喜草;(2)不同草本类型和同一草本不同土层之间土壤渗透性存在较大差异,且各草本土壤渗透性随土层深度的增加而降低;相对于裸地而言,4种草本均能显著增强土壤渗透性,其土壤渗透性优劣表现为:香根草＞紫花苜蓿＞百喜草＞狗牙根;(3)土壤的初始入渗率、稳渗率、平均渗透率和渗透总量等各参数均随根长密度和根表面积密度增大而增强,且与直径介于0.5-5 mm不同径级的根系特征之间存在明显的相关性,故根系对土壤渗透性的增强作用主要归功于0.5-5 mm径级的根长密度和根表面积密度;(4)根长密度、根表面积密度对考斯加科夫入渗模型参数K和a有较大影响,随着根长密度和根表面积密度的增加,表征土壤初始入渗率的K值逐渐增大,而表征入渗能力衰减的参数a逐渐减小.     

Stain Solubilities Part III

Ethylenediaminetetraacetic acid (EDTA) solution is used to decalcify bone specimens for histological examination. Sodium hydroxide (NaOH) has been used to dissolve EDTA and to bring EDTA solutions to neutral pH. This solution, however, requires several weeks to decalcify bone specimens. We investigated a new de-calcification fluid using concentrated ammonium hydroxide (NH₄OH) to dissolve EDTA and to adjust the pH to neutral. Decalcification was performed using a magnetic stirrer with and without vacuum, or with a sonic cleaner. Decalcification end point was confirmed using both the weight loss and X-ray methods. After decalcification, specimens were processed through paraffin and sections were stained with hematoxylin and eosin. Decalcification employing NH₄OH required an average of six days. Light microscopy indicated good retention of cellular detail.     

Cell Budding from Normal Appearing Epithelia: A Predictor of Colorectal Cancer Metastasis?

Background: Colorectal carcinogenesis is believed to be a multi-stage process that originates with a localized adenoma, which linearly progresses to an intra-mucosal carcinoma, to an invasive lesion, and finally to metastatic cancer. This progression model is supported by tissue culture and animal model studies, but it is difficult to reconcile with several well-established observations, principally among these are that up to 25% of early stage (Stage I/II), node-negative colorectal cancer (CRC) develop distant metastasis, and that circulating CRC cells are undetectable in peripheral blood samples of up to 50% of patients with confirmed metastasis, but more than 30% of patients with no detectable metastasis exhibit such cells. The mechanism responsible for this diverse behavior is unknown, and there are no effective means to identify patients with pending, or who are at high risk for, developing metastatic CRC.Novel findings: Our previous studies of human breast and prostate cancer have shown that cancer invasion arises from the convergence of a tissue injury, the innate immune response to that injury, and the presence of tumor stem cells within tumor capsules at the site of the injury. Focal degeneration of a capsule due to age or disease attracts lymphocyte infiltration that degrades the degenerating capsules resulting in the formation of a focal disruption in the capsule, which selectively favors proliferating or “budding” of the underlying tumor stem cells. Our recent studies suggest that lymphocyte infiltration also triggers metastasis by disrupting the intercellular junctions and surface adhesion molecules within the proliferating cell buds causing their dissociation. Then, lymphocytes and tumor cells are conjoined through membrane fusion to form tumor-lymphocyte chimeras (TLCs) that allows the tumor stem cell to avail itself of the lymphocyte''s natural ability to migrate and breach cell barriers in order to intravasate and to travel to distant organs. Our most recent studies of human CRC have detected nearly identical focal capsule disruptions, lymphocyte infiltration, budding cells, and the formation of TLCs. Our studies have further shown that age- and type-matched node-positive and -negative CRC have a significantly different morphological and immunohistochemical profile and that the majority of lymphatic ducts with disseminated cells are located within the mucosa adjacent to morphologically normal appearing epithelial structures that express a stem cell-related marker.New hypothesis: Based on these findings and the growth patterns of budding cells revealed by double immunohistochemistry, we further hypothesize that metastatic spread is an early event of carcinogenesis and that budding cells overlying focal capsule disruptions represent invasion- and metastasis-initiating cells that follow one of four pathways to progress: (1) to undergo extensive in situ proliferation leading to the formation of tumor nests that subsequently invade the submucosa, (2) to migrate with associated lymphocytes functioning as “seeds” to grow in new sites, (3) to migrate and intravasate into pre-existing vascular structures by forming TLCs, or (4) to intravasate into vascular structures that are generated by the budding cells themselves. We also propose that only node-positive cases harbor stem cells with the potential for multi-lineage differentiation and unique surface markers that permit intravasation.