树鼩主动脉内皮细胞株的建立及其生物学特性的研究

将树鼩胸主动脉分层剥离,用组织块贴壁法,体外培养出主动脉内皮细胞,历经一年,传至23代,命名为TSaec-8910。倒置显微镜下细胞单层生长,呈铺路石样镶嵌排列,第Ⅷ因子相关抗原阳性,透射电镜观察,细胞质内未找到Weibel-Palade小体。细胞生长曲线及分裂指数示9～12d汇合成单层,按1:2或1:3传代,传代间隔为lO～14d,细胞冻存复苏后接种存活率为31.5％,细胞染色体检查为二倍体细胞,2n=62,雄性。内皮细胞生长因子、上皮细胞生长因子、条件培养基和附着底物对TSaec-8910细胞有明显影响,细胞在玻璃瓶壁上贴壁时间为24～18h,而在涂有鼠尾胶瓶壁则为4h左右,内皮细胞生长因子、上皮细胞生长因子能促进TSaec-8910细胞贴壁和增殖,20％TSaec-8910细胞条件培养基亦能良好地维持细胞形态。     

High resolution radiocarbon spike confirms tree ring dating with low sample depth

Radiocarbon (¹⁴C) has been used to date carbon-rich objects in Earth science, archeology, and history since the 1940s. New methods, using spikes in ¹⁴C caused by solar proton events, can be used to annually date wood when crossdating is not possible, such as when sample size is low, samples are floating in time, or external disturbances lead to insecure dates. Here, we use a spike in radiocarbon during a solar energetic particle (SEP) event in 774/775 CE to confirm crossdating of a poorly-replicated King Billy pine (Athrotaxis selaginoides) chronology. Low sample depth between 1498 and 1523 CE (two trees) prevented confident dating of the early period of the chronology. Three core samples with strong correlation with the master chronology that likely included the 774/775 CE Miyake SEP event were identified for radiocarbon isotope analysis. We sectioned segments centered on the estimated 774/775 CE date and then isolated the holocellulose in each sample. Samples were sent to an accelerator mass spectrometry (AMS) for radiocarbon measurements. The AMS data confirmed the crossdating accuracy of the tree ring series and reinforces the applicability of this technique to anchor poorly dated tree ring series in time. In addition, we found sample processing with a microtome proved superior for holocellulose extractions and yielded more accurate ¹⁴C measurements. We recommend sampling with a microtome, processing at least three samples per year, and including sample masses greater than 100 ug C to confirm dating using radiocarbon spikes.     

Stanford A型主动脉夹层孙氏手术患者术后血流感染的影响因素及术前PCT、IL-6、D-D的预测价值研究

摘要 目的：分析Stanford A型主动脉夹层（AD）孙氏手术患者术后血流感染（BSI）的影响因素,并探讨术前血清降钙素原（PCT）、白细胞介素-6（IL-6）、D-二聚体（D-D）对术后发生BSI的预测价值。方法：选取2019年1月～2022年1月贵州医科大学附属医院收治的236例接受孙氏手术的Stanford A型AD患者,根据术后是否BSI分为BSI组和非BSI组。收集患者基础资料和实验室指标,采用多因素Logistic回归分析Stanford A型AD孙氏手术患者术后发生BSI的影响因素,采用受试者工作特征（ROC）曲线分析血清PCT、IL-6、D-D水平对Stanford A型AD孙氏手术患者术后发生BSI的预测价值。结果：BSI组年龄≥60岁、糖尿病史、机械通气、气管切开、人工瓣膜植入比例和术后24 h引流量、血清C反应蛋白、PCT、IL-6、D-D水平高于非BSI组,手术时间、心包纵隔管保留时间长于非BSI组（P＜0.05）。多因素Logistic回归分析显示,年龄≥60岁、糖尿病史、机械通气、气管切开、术后24 h引流量上升,血清PCT、IL-6、D-D水平上升为Stanford A型AD孙氏手术患者术后发生BSI的危险因素（P＜0.05）。ROC曲线分析显示,血清PCT、IL-6、D-D三项联合预测的Stanford A型AD孙氏手术患者术后发生BSI的曲线下面积大于单独预测。结论：年龄、糖尿病史、机械通气、气管切开、术后24 h引流量、血清PCT、IL-6、D-D水平是Stanford A型AD孙氏手术患者术后发生BSI的影响因素,术前血清PCT、IL-6、D-D水平可作为Stanford A型AD孙氏手术患者术后发生BSI的辅助预测指标。     

Tritium NMR studies of the human carbonic anhydrase I–benzenesulfonamide complex

Tritium NMR spectroscopy has been used to examine the complexformed by [4-³H]benzenesulfon-amide and human carbonicanhydrase I. The results show that in solution the inhibitor forms a 1:1complex with the enzyme. A 100-spin computational model of the system,constructed with reference to crystallographic results, was used tointerpret tritium relaxation behavior and ³H{¹H}NOEs. The analysis shows that the rate of dissociation of theenzyme–sulfonamide complex is 0.35 s^–1 and thatthe aromatic ring of the inhibitor undergoes rapid rotation while complexed.     

Stable carbon isotopes in tree rings of beech: climatic versus site-related influences

 Stable carbon isotopes in tree rings are a promising tool in palaeoclimate research, provided attempts are made to disentangle climatic from local effects (e.g. soil properties, competition, light). The ¹³C/¹²C variations in cellulose of tree rings of beech (Fagus sylvatica) were determined at several sites in the Swiss Central Plateau covering the last 50 years. We chose sites which differ in moisture conditions and sampled cores from four to six trees per site. The mean ¹³C/¹²C series from the different dry sites (distant by up to 40 km) are closely interrelated suggesting a common external cause. Correlation analysis with climate data proved the total precipitation in the months May, June and July to have the strongest effect on the carbon isotopes (r =  – 0.73). This result is in agreement with the commonly used model which relates the isotope discrimination to the water use efficiency. On the other hand, the isotope series of the wet sites are not as well correlated to the climate. At two of the sites (a dry and a humid) tree ring width suddenly increased. We used this effect as a test-case to study the influence of local growth conditions on the climate-isotope relationship. Received: 17 April 1996 / Accepted: 2 September 1996     

Biotransformation of diphenyl ether by the yeastTrichosporon beigelii SBUG 752

Trichosporon beigelii SBUG 752 was able to transform diphenyl ether. By TLC, HPLC, GC, GC-MS, NMR- and UV-spectroscopy, several oxidation products were identified. The primary attack was initiated by a monooxygenation step, resulting in the formation of 4-hydroxydiphenyl ether, 2-hydroxydiphenyl ether and 3-hydroxydiphenyl ether (48:47:5). Further oxidation led to 3,4-dihydroxydiphenyl ether. As a characteristic product resulting from the cleavage of an aromatic ring, the lactone of 2-hydroxy-4-phenoxymuconic acid was identified. The possible mechanism of ring cleavage to yield this metabolite is discussed.     

Effects of Macroposthonia xenoplax on the Growth of Concord Grape

Concord grape (Vitis labrusca) plants were inoculated with Macroposthonia xenoplax at levels of 100, 1,000, and 10,000 nematodes. After 4 months, plants inoculated with 10,000 M. xenoplax were stunted, and root systems were darker and had fewer feeder roots than those in other treatments. The lower nematode inoculation levels suppressed top growth but did not affect root growth. M. xenoplax reproduced well on Concord grapes.     

Alkaline opening of imidazole ring of 7-methylguanosine. 2. Further studies on reaction mechanisms and products

High performance liquid chromatography (HPLC) was used to follow the kinetics of the alkaline induced opening of the imidazole ring of 7-methylguanosine (7-meGuo). The kinetics show an initial rapid formation of a major transient intermediate and some minor products that were chromato-graphically separable into seven peaks. This phase of the reaction is followed by the formation of a dominant pyrimidine derivative whose liquid chromatography retention time in a 6% methanol, 0.01 M NH₄H₂PO₄ (pH 5.1) solvent is 6 min; during the rest of the reaction time this dominant species was progressively converted to a co-dominant species that has a 4.5-min column retention. Mass spectroscopy confirmed the existence of two species of ring opened 7-methylguanine (7-meGua), one formylated and another deformylated. Schiff's reaction demonstrated that the species in the second HPLC peak is the formylated one. The ring opened 7-methylguanine (rom⁷Gua) released by formamidopyrimidine (FAPy)-DNA glycosylase was shown to coelute with the formylated species. These results demonstrate that the enzyme excises formylated rom⁷Gua from DNA Analysis of rom⁷Guo by NMR showed that there are two signals assignable to methyl protons and two to formyl protons. These chemical shifts were interpreted as being due to the opening of the imidazole ring at two sites and to the formation of formylated and deformylated rom⁷Gua.     

Degree-day Models for Predicting Egg Hatch and Population Increase of Criconemella xenoplax

A degree-day model was derived to predict egg hatch for Criconemella xenoplax. Eggs collected from gravid females were incubated in distilled water at constant temperatures of 10-35 C. Sixty-six percent of all eggs hatched between 13 and 32 C, and 42% hatched at 10 C. All eggs aborted above 32.5 C. Between 25 and 32 C, 8.5 ± 0.5 days were required for egg hatch. Degree-day requirement for egg hatch at 10-30 C was estimated to be 154 ± 5 with a base of 9.03 ± 0.04 C. This base of 9 C was adopted in studies of the relationship between degree-days and nematode population increase on Prunus seedlings grown 9-11 weeks in a greenhouse. Degree-day accumulations were based upon daily averages from maximum and minimum air temperatures. Ratios of final to initial population densities exhibited an exponential pattern in relation to degree-day accumulations with proportionate doubling increment of 0.100 ± 0.049 every 139 ± 8 degree-days. These results provide a means of predicting nematode population increase under greenhouse conditions and a basis for choosing sampling intervals when evaluating nematode multiplication.