Enzymatic dephosphorylation of endogenous and exogenous dolichyl monophosphate by calf brain membranes

Calf brain membranes have been shown to enzymatically dephosphorylate endogenous and partially purified, exogenous dolichyl [³²P]monophosphate. The properties and specificity of the dolichyl monophosphatase activity have been studied by following the release of [³²P]phosphate from exogenous dolichyl [³²P]monophosphate added in a dispersion with Triton X-100. The calf brain phosphatase (1) is inhibited by Mn²⁺, Mg²⁺, Ca²⁺, fluoride, and phosphate; (2) exhibits a neutral pH optimum; and (3) has an apparent K_m of 200 μm for dolichyl monophosphate. Dolichyl monophosphatase activity can be distinguished from phosphatidate phosphatase on the basis of their responses to fluoride and phosphate. Based on differential thermolability and the effects of divalent cations and EDTA, the calf brain dolichyl monophosphatase can also be discriminated from the general phosphatase activity assayed with p-nitrophenyl phosphate. Dolichyl monophosphatase activity can be solubilized by treating microsomes with Triton X-100. The enzymatic dephosphorylation of exogenous dolichyl [³²P]monophosphate catalyzed by particulate and detergent-solubilized preparations is negligibly affected by equimolar concentrations of ATP and an assortment of phosphomonoesters, including phosphatidic acid and hexadecyl phosphate. A reduction of approximately 40% in dolichyl monophosphatase activity is observed in the presence of equimolar amounts of retinyl monophosphate. Overall, these results represent good evidence for the presence of a neutral polyisoprenyl monophosphatase in central nervous tissue.     

Cellular mechanism of endotoxin unresponsiveness in C3H/HeJ mice.

B cells from C3H/HeJ mice fail to respond to an endotoxin (LPS K235) which is mitogenic for normal mice including the closely related C3H/HeN strain. The cellular basis for this unresponsive state has been investigated. The C3H/HeJ mice have normal numbers of B cells, which are capable of normal responses to other B cell mitogens, such as polyinosinic acid (Poly I). Addition of normal macrophages or spleen cells fails to reconstitute the normal response. Furthermore, neither macrophages nor spleen cells from the C3H/HeJ strain suppress the normal C3H/HeN spleen cells. Finally, spleen cells enriched for B cells by the removal of macrophages or T cells demonstrate the same differences in responsiveness to LPS. These results indicate that LPS unresponsiveness is a defect of the B cell itself and not due to suppressor cells or the absence of helper cells. When LPS is added to Poly I-stimulated cultures, there is additional enhancement of the response of normal C3H/HeN spleen cells. However, LPS causes a dose-dependent suppression of the Poly I response of C3H/HeJ spleen cells. This suppression is dependent on the time of addition of LPS to the Poly I-stimulated cultures. These data are interpreted as indicating that the binding of LPS to the membrane of C3H/HeJ B cells results in their inactivation or suppression, and that this is the basis of LPS unresponsiveness in this mouse strain.     

Naturally occurring hypertrophic pyloric stenosis in the domestic rabbit.

Hypertrophic pyloric stenosis was observed to occur naturally in laboratory rabbits. Three cases in juvenile and adult rabbits and their antemortem histories were examined. The gross and microscopic pathology were studied. It was shown that not only the pylorus, but the stomach as a whole was increased in size both relatively and absolutely. The thickness of the pylorus was doubled, but its circumference was not increased, in hypertrophic stenosis. The chief histologic finding was hypertrophy of circular and longitudinal smooth muscles and their enveloping fascia. The myenteric plexi were essentially normal in appearance. The literature on a similar condition in man, dog, and cat was reviewed.     

The immune response to a synthetic amino acid terpolymer in man: relationship to HL-A type.

The immune response to the synthetic amino acid terpolymer (L-glutamic acid-55 L-lysine-33 L-tyrosine15)n (GLT) was studied in normal human volunteers. Delayed skin test reactivity to this antigen was seen in 34 of 61 subjects immunized with 150 mug of GLT. No antibody to GLT was detected in these responding individuals. There was a close correlation between the in vivo skin reactivity of volunteers to GLT and the ability of their lymphocytes to produce migration inhibitory factor (MIF) in response to GLT in vitro. However, a similar correlation was not seen when the in vitro proliferative response of lymphocytes to GLT, as measured by [methyl-3H] thymidine ([3H] T dR) incorporation, was assayed. HL-A typing of volunteers was studied to determine if responsiveness to GLT was correlated to HL-A type. No statistical association was seen after correction was made for the number of individual HL-A antigens.     

超声技术在抑郁症诊疗中的作用研究及应用进展

超声波作为一种机械振动波,兼具波动效应、力学效应和热效应.这3种效应在临床中均有较大应用价值,可用于疾病的成像诊断、辅助给药、调控以及热消融治疗等.超声技术所具有的非侵入性、穿透力强、空间分辨率高等特性,使其在神经系统疾病的诊断和治疗中具有广泛的应用前景.而抑郁症作为一种常见的精神疾病,其诊断和治疗都面临很大的困难.因此,大量学者将超声技术应用于抑郁症诊疗.本文主要从超声成像、超声定点给药、超声调控、超声诱导抑郁几个方面总结近十年来超声技术在抑郁症中的应用,以期为研究抑郁症发病机制及诊疗提供一定的参考和帮助.     

京津冀城市群土地利用变化对地表径流的影响

城市化的显著特征之一是地表景观格局被人为改变,大量硬化地表覆盖、取代了原本自然或半自然的土地覆盖类型,极大地干扰了区域水文循环过程。其中,最直接的体现是对地表径流过程的影响。城市群作为当前我国城市化的重要模式,其聚集连片的扩张模式,对区域地表径流过程的干扰尤为严重。以京津冀特大城市群为研究区域,应用长期水文影响评价模型(L-THIA),以1980、1990、2000、2010、2015年5期土地利用数据、土壤数据以及1950—2015年逐日降雨数据为输入,模拟计算了不同土地利用/覆被格局对多年平均地表径流量的影响。结果表明,(1)经过率定的L-THIA模型能够较为准确地模拟京津冀城市群地区的地表径流分布特征,模型模拟误差在±10%内;(2)1980—2015年,京津冀城市群地区不透水地表面积急剧增加,其净增长值为12690.14 km~2。北京与天津等超大城市不透水地表面积增加最明显;(3)随着土地利用格局的变化,京津冀地区地表径流量呈逐年增长趋势。1980—2015年,京津冀城市群地区地表径流量的绝对增长值为17.84亿m~3,增幅11.83%。其中,1990—2000年及2010—2015年期间地表径流年均增长率较大,分别为0.36%与0.46%。对地表径流贡献较大的土地利用类型为耕地和不透水地表,其5期土地利用情景下的平均产流占比分别为35.38%、22.71%;(4)城市尺度上,不同城市的标准化年均径流深(NAARD)存在较大差异。天津、石家庄的产流能力较强,承德、衡水等城市的产流能力较弱,北京市的标准化年均径流深处于中等水平。另一方面,不同城市标准化年均径流深增长规律也存在较大差异。1980—2015年,天津市的NAARD增长最多,承德市增长最少,北京市的NAARD增长处于中等水平。本文对于京津冀城市群水文过程的时空演变研究以及国土空间优化指导具有参考意义。     

老爷岭南部狍冬季移动、卧息生境选择及其适宜性评价

在动物生境研究中,移动生境和卧息生境是生境研究的焦点。开展移动生境和卧息生境选择,并在此基础上进行生境评价,有利于深入了解动物对移动和卧息生境条件的需求,制定科学合理的栖息地保护计划。以东北虎（Panthera tigris altaica）的主要猎物物种之一-狍（Capreolus pygargus）为研究对象,于2017-2019年冬季积雪覆盖期在老爷岭南部通过随机布设28个大样方和84条用于足迹链跟踪的样线收集狍的移动点和卧息点信息,再结合近年来收集的东北虎出现点,利用广义可加模型（GAM）和最大熵模型（MaxEnt）进行狍移动、卧息生境选择及评价研究。移动生境选择研究表明,狍在移动的过程中偏好选择坡度小、距农田距离>500 m、远离道路、居民点和低海拔或较高海拔的区域;移动生境评价分析表明,移动适宜和次适宜生境面积之和为1318.16 km²,占研究区域面积的51.28%,当加入虎活动点影响因子后,狍移动适宜和次适宜生境面积之和为901.52 km²,适宜和次适宜生境面积之和减少了31.61%。狍卧息生境选择研究表明,水源、农田、道路和雪深是影响狍卧息的关键因素,其中雪深对狍卧息生境选择的贡献率达到70.13%;卧息生境评价表明,卧息适宜和次适宜生境面积之和为1243.77 km²,占研究区域面积的48.39%,当加入虎出现点因子后,适宜生境和次适宜生境面积之和减少了61.00%,仅为485.02 km²。研究认为,虎的出现对狍移动和卧息生境选择均产生影响,虎的活动及捕食行为可能会减少狍的活动范围和频次,狍远离虎活动区域卧息休息,压缩了狍适宜卧息的空间。     

人脂肪间充质干细胞外泌体通过上调β-catenin、c-Myc和细胞周期蛋白表达促进表皮干细胞增殖

本研究探讨人脂肪间充质干细胞来源的外泌体(ADSC-Exos)对人表皮干细胞(EpSCs)增殖的影响及机制.首先使用Ⅰ型胶原酶分离人脂肪组织ADSCs,中性蛋白酶Ⅱ和胰酶分离人皮肤组织EpSCs;采用ExoQuick-TC试剂分离ADSCs培养上清中的外泌体.然后通过MTT法、细胞免疫荧光检测Ki67,BrdU掺入实验检测ADSC-Exos对EpSCs增殖的影响,流式细胞术检测ADSC-Exos对EpSCs细胞周期的影响.通过HE染色、免疫组化染色检测细胞增殖标志分子及表皮干细胞标志分子的表达,以观察ADSC-Exos对体外培养皮肤组织的结构及EpSCs增殖的影响.结果显示:ADSC-Exos能以浓度依赖性和时间依赖性的方式促进EpSCs增殖,增加S期细胞数,减少G1期细胞数;ADSC-Exos也能促进体外培养皮肤组织中的EpSCs增殖.机制研究发现:ADSC-Exos对EpSCs的促增殖作用能部分被β-catenin抑制剂XAV-939或c-Myc抑制剂10058-F4所抑制.ADSC-Exos能促进EpSCs表达β-catenin、c-Myc及cyclin E1、A2、D1,XAV-939能抑制ADSC-Exos诱导的β-catenin、c-Myc以及cyclinE1、A2、D1表达,10058-F4能抑制ADSC-Exos诱导的c-Myc和cyclin D1、A2、E1表达.综上,ADSC-Exos能显著促进EpSCs增殖,其作用部分是由上调β-catenin、c-Myc和cyclinE1、A2、D1表达所介导.