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121.
小儿罕见真菌感染的临床报道 总被引:3,自引:3,他引:0
目的 探讨念珠菌病的新类型和新条件下小儿真菌感染的临床表现和致病菌。方法 回顾性收集1975~2005年的临床资料44例,进行体外毛发感染试验、电镜观察、动物试验,流式细胞(FCM)、随机括增多态性DNA(RAPD)以及DNA基因序列检测等。结果 ①累计发现44例婴儿头部念珠菌病,其中病期长者可感染头发。②粉末毕赤酵母可致婴儿皮肤感染。③一种罕见的林生地霉可致脓癣样地霉病。结论 我们发现的婴儿头部念珠菌病,慢性皮肤、黏膜念珠菌病伴皮肤粉末毕赤酵母感染和罕见的林生地霉引起儿童脓癣样地霉病,均为文献率先报道,对防治和降低念珠菌病和其他酵母样真菌感染患者的死亡率有一定意义。 相似文献
122.
利用正交实验方法,以甘油、海藻糖、蔗糖和牛血清蛋白为因素,对嗜酸氧化亚铁硫杆菌(Acididfiobacillus ferrooxidans,A.ferrooxidans)冷冻干燥保护剂的最优化配比进行了研究。直观分析、因素指标分析和方差分析的结果表明:由甘油、海藻糖、蔗糖和牛血清蛋白组成的冷冻干燥保护剂中,对存活率影响的主次顺序依次为:甘油〉海藻糖〉牛血清蛋白〉蔗糖。保护剂的最优化组合为甘油5%、海藻糖15%、蔗糖18%、牛血清蛋白10%。经过验证,该组合的保护剂可使冷冻干燥嗜酸氧化亚铁硫杆菌的存活率达到94%。 相似文献
123.
124.
Maojun Wang Jianying Li Pengcheng Wang Fang Liu Zhenping Liu Guannan Zhao Zhongping Xu Liuling Pei Corrinne E Grover Jonathan F Wendel Kunbo Wang Xianlong Zhang 《Molecular biology and evolution》2021,38(9):3621
Transposable element (TE) amplification has been recognized as a driving force mediating genome size expansion and evolution, but the consequences for shaping 3D genomic architecture remains largely unknown in plants. Here, we report reference-grade genome assemblies for three species of cotton ranging 3-fold in genome size, namely Gossypium rotundifolium (K2), G. arboreum (A2), and G. raimondii (D5), using Oxford Nanopore Technologies. Comparative genome analyses document the details of lineage-specific TE amplification contributing to the large genome size differences (K2, 2.44 Gb; A2, 1.62 Gb; D5, 750.19 Mb) and indicate relatively conserved gene content and synteny relationships among genomes. We found that approximately 17% of syntenic genes exhibit chromatin status change between active (“A”) and inactive (“B”) compartments, and TE amplification was associated with the increase of the proportion of A compartment in gene regions (∼7,000 genes) in K2 and A2 relative to D5. Only 42% of topologically associating domain (TAD) boundaries were conserved among the three genomes. Our data implicate recent amplification of TEs following the formation of lineage-specific TAD boundaries. This study sheds light on the role of transposon-mediated genome expansion in the evolution of higher-order chromatin structure in plants. 相似文献
125.
K Li R Xing S Liu Y Qin B Li X Wang P Li 《International journal of biological macromolecules》2012,51(5):826-830
The separation of chitooligomers (COS) with well-defined degree of polymerization (DP) is of interest to further study their bioactivity. However, there has been no report on separation of chitooligomers with DP>6 and the activity of these oligomers is unknown. This paper focuses on separating COS with DP>6 and five fractions were separated from the prepared fully deacetylated chitooligomers mixture by CM Sepharose Fast Flow column and analyzed by HPLC, which mainly contained glucosamine oligomers with DP6-7 (41.31%, 50.22%), DP7-8 (22.47%, 70.13%), DP9-10 (53.06%, 27.99%), DP10-12 (18.45%, 49.36%, 22.31%), and DP>12, respectively. The superoxide radical scavenging activity of each fraction was investigated. The oligomers with DP ranging from 10 to 12 exhibited higher scavenging activity than other fractions and in combination with the DP distribution of fractions, it was further concluded that the chitooligomers with DP11 was likely to be optimal for scavenging superoxide radical activity. 相似文献
126.
【目的】γ-丁基甜菜碱羟化酶是生物体内合成L-肉碱的关键酶。从假单胞菌(Pseudomonas sp.)L-1中克隆γ-丁基甜菜碱羟化酶基因,实现其在大肠杆菌(Escherichia coli)中的高效表达,并对表达产物进行酶学性质分析,为生物转化生产L-肉碱奠定基础。【方法】通过PCR克隆γ-丁基甜菜碱羟化酶基因,并将其开放阅读框(ORF)克隆至融合表达载体pET-15b;表达产物经His.Bind Resin纯化后对BBH进行酶学性质及三维空间结构分析;并以静止细胞进行L-肉碱的转化。【结果】成功地克隆了一个γ-丁基甜菜碱羟化酶基因bbh(GenBank:JQ250036),并实现了其在E.coli中的高效表达。融合蛋白以同源二聚体的形式存在,单个亚基的分子量约46.5 kDa,最适反应温度为30℃,最适反应pH为7.5。该酶在45℃以下稳定。在pH6.0时该酶有最高的pH稳定性。以表达bbh基因的重组大肠杆菌静止细胞转化L-肉碱,L-肉碱产量可达12.7mmol/L。【结论】Pseudomonas sp.L-1γ-丁基甜菜碱羟化酶与现有报道的bbh基因有较大的差异。由该基因表达的γ-丁基甜菜碱羟化酶能有效地转化γ-丁基甜菜碱生成L-肉碱。本研究不仅丰富了γ-丁基甜菜碱羟化酶基因资源,而且为L-肉碱的生物转化提供了一种新的转化方案。 相似文献
127.
In Positron Emission Tomography (PET), an optimal estimate of the radioactivity concentration is obtained from the measured emission data under certain criteria. So far, all the well-known statistical reconstruction algorithms require exactly known system probability matrix a priori, and the quality of such system model largely determines the quality of the reconstructed images. In this paper, we propose an algorithm for PET image reconstruction for the real world case where the PET system model is subject to uncertainties. The method counts PET reconstruction as a regularization problem and the image estimation is achieved by means of an uncertainty weighted least squares framework. The performance of our work is evaluated with the Shepp-Logan simulated and real phantom data, which demonstrates significant improvements in image quality over the least squares reconstruction efforts. 相似文献
128.
The change of BOLD signal relies heavily upon the resting blood volume fraction ([Formula: see text]) associated with regional vasculature. However, existing hemodynamic data assimilation studies pretermit such concern. They simply assign the value in a physiologically plausible range to get over ill-conditioning of the assimilation problem and fail to explore actual [Formula: see text]. Such performance might lead to unreliable model estimation. In this work, we present the first exploration of the influence of [Formula: see text] on fMRI data assimilation, where actual [Formula: see text] within a given cortical area was calibrated by an MR angiography experiment and then was augmented into the assimilation scheme. We have investigated the impact of [Formula: see text] on single-region data assimilation and multi-region data assimilation (dynamic cause modeling, DCM) in a classical flashing checkerboard experiment. Results show that the employment of an assumed [Formula: see text] in fMRI data assimilation is only suitable for fMRI signal reconstruction and activation detection grounded on this signal, and not suitable for estimation of unobserved states and effective connectivity study. We thereby argue that introducing physically realistic [Formula: see text] in the assimilation process may provide more reliable estimation of physiological information, which contributes to a better understanding of the underlying hemodynamic processes. Such an effort is valuable and should be well appreciated. 相似文献
129.
Xiaoming Zhang Lirong Song Pengcheng Zhang Jiawan He Yongding Liu Hiroshi Matsuura Makoto M. Watanabe 《Phycological Research》2012,60(1):20-26
Tadpoles of Rana grylio were raised as edible frogs in fishponds of Guanqiao in Wuhan City, Hubei, China, during cyanobacterial blooms from June to October. The dominant cyanobacterial species was Microcystis, which was found to be lethally toxic by intraperitoneal (i.p.) mouse bioassay. Little is known about the effect of tadpoles on toxic cyanobacterial blooms. To evaluate the potential of the tadpoles to graze on cyanobacterial blooms, the tadpoles were fed on Microcystis collected from the field in the laboratory. The Microcystis cells decreased from 1.19 × 107 cells mL?1 to 3.23 × 106 cells mL?1, with a sharp reduction of 73% of the initial Microcystis population observed in the first 24 h after introduction of the tadpoles. The ponds containing tadpoles had a markedly lower density of Microcystis than those lacking tadpoles. Tadpoles exposed to either cultured Microcystis aeruginosa (NIES–90, 2.768 µg microcystins mg–1 dw–1) cells or lysed M. aeruginosa cells grew well, however, indicating that they were unaffected by Microcystis toxins. We found a significant increase in tadpole body weight after feeding on either field Microcystis or cultured M. aeruginosa. The mean increase in individual body weight was 20 mg day?1 when fed on Microcystis from the pond, and 7 mg day?1 when fed on M. aeruginosa from culture. Our study strongly suggested that there is a direct trophic relationship between R. grylio tadpoles and toxic Microcystis blooms and they possess the potential to graze on toxic Microcystis. The results imply that R. grylio tadpoles may play an important ecological role in reducing toxic cyanobacterial blooms caused by Microcystis. 相似文献
130.
Astrocytes participate in brain functions through Ca2+ signals, including Ca2+ waves and Ca2+ oscillations. Currently the mechanisms of Ca2+ signals in astrocytes are not fully clear. Here, we present a computational model to specify the relative contributions of different Ca2+ flows between the extracellular space, the cytoplasm and the endoplasmic reticulum of astrocytes to the generation of spontaneous Ca2+ oscillations (CASs) and cortical spreading depression (CSD)-triggered Ca2+ waves (CSDCWs) in a one-dimensional astrocyte network. This model shows that CASs depend primarily on Ca2+ released from internal stores of astrocytes, and CSDCWs depend mainly on voltage-gated Ca2+ influx. It predicts that voltage-gated Ca2+ influx is able to generate Ca2+ waves during the process of CSD even after depleting internal Ca2+ stores. Furthermore, the model investigates the interactions between CASs and CSDCWs and shows that the pass of CSDCWs suppresses CASs, whereas CASs do not prevent the generation of CSDCWs. This work quantitatively analyzes the generation of astrocytic Ca2+ signals and indicates different mechanisms underlying CSDCWs and non-CSDCWs. Research on the different types of Ca2+ signals might help to understand the ways by which astrocytes participate in information processing in brain functions. 相似文献