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941.
Eduardo Peil Marques Fernanda Silva Ferreira Tiago Marcon Santos Caroline Acauan Prezzi Leo A.M. Martins Larissa Daniele Bobermin André Quincozes-Santos Angela T.S. Wyse 《生物化学与生物物理学报:疾病的分子基础》2019,1865(11):165529
Guanidinoacetate Methyltransferase deficiency is an inborn error of metabolism that results in decreased creatine and increased guanidinoacetate (GAA) levels. Patients present neurological symptoms whose mechanisms are unclear. We investigated the effects of an intrastriatal administration of 10 μM of GAA (0.02 nmol/striatum) on energy metabolism, redox state, inflammation, glutamate homeostasis, and activities/immunocontents of acetylcholinesterase and Na+,K+-ATPase, as well as on memory acquisition. The neuroprotective role of creatine was also investigated. Male Wistar rats were pretreated with creatine (50 mg/kg) or saline for 7 days underwenting stereotactic surgery. Forty-eight hours after surgery, the animals (then sixty-days-old) were divided into groups: Control, GAA, GAA + Creatine, and Creatine. Experiments were performed 30 min after intrastriatal infusion. GAA decreased SDH, complexes II and IV activities, and ATP levels, but had no effect on mitochondrial mass/membrane potential. Creatine totally prevented SDH and complex II, and partially prevented COX and ATP alterations. GAA increased dichlorofluorescein levels and decreased superoxide dismutase and catalase activities. Creatine only prevented catalase and dichlorofluorescein alterations. GAA increased cytokines, nitrites levels and acetylcholinesterase activity, but not its immunocontent. Creatine prevented such effects, except nitrite levels. GAA decreased glutamate uptake, but had no effect on the immunocontent of its transporters. GAA decreased Na+,K+-ATPase activity and increased the immunocontent of its α3 subunit. The performance on the novel object recognition task was also impaired. Creatine partially prevented the changes in glutamate uptake and Na+,K+-ATPase activity, and completely prevented the memory impairment. This study helps to elucidate the protective effects of creatine against the damage caused by GAA. 相似文献
942.
Jun Li Jie Xu Xinghua Qin Hongyan Yang Juntao Han Yanhui Jia Huayu Zhu Liang Zhu Jia Li Wenjun Xie Dahai Hu Xing Zhang Feng Gao 《生物化学与生物物理学报:疾病的分子基础》2019,1865(2):275-284
Background
Acute hyperglycemia is regarded as a risk factor for critically ill patients; however, insufficient understanding of its nature and underlying mechanisms hinders widespread adoption of glycemic control in critical care units.Methods
A single center, prospective cohort study recruiting 107 burn patients and 62 controls was conducted to characterize the early phase of acute hyperglycemia in burn patients. A total of 1643 blood samples were collected and analyzed over the entire postburn 200?h. A mouse severe burn model was used to study the underlying mechanisms of acute hyperglycemia postburn.Results
The dynamic change of postburn blood glucose represented a distinctive pattern in amplitude and duration that was in parallel with the degree of burn injury. Multiple linear regressions revealed that serum insulin, glucagon and glucocorticoid were the major factors affecting blood glucose postburn. Particularly, extensive burns impaired capacity and responsiveness of pancreatic insulin secretion, which was associated with increased serum IL-1β in burn patients. Mechanistically, acute IL-1β elevation specifically induced pancreatic beta cell apoptosis and dampened capacity of insulin secretion, leading to postburn hyperglycemia in burned mice. More importantly, inhibition of IL-1β not only alleviated pancreatic beta cell apoptosis, but also attenuated hyperglycemia and improved survival of burned mice.Conclusions
Our findings reveal a novel mechanism of acute hyperglycemia postburn in which impaired insulin secretory capacity mediated by IL-1β leads to acute hyperglycemia. These data suggest that targeting IL-1β to restore endogenous insulin secretory function may be a novel glycemic control strategy to improve outcomes for burn patients. 相似文献943.
We previously described the entity of cold-induced apoptosis to rat hepatocytes and characterized its major, iron-dependent pathway. However, after cold incubation in some solutions, e.g. cell culture medium, hepatocytes show an additional, yet uncharacterized component of cold-induced injury. We here assessed the effects of organ preservation solutions on both components of cold-induced injury and tried to further characterize the iron-independent component. None of the preservation solutions (University of Wisconsin, histidine-tryptophan-ketoglutarate, Euro-Collins, histidine-lactobionate, sodium-lactobionate-sucrose and Celsior solutions) provided significant protection against cold-induced cell injury (LDH release after 24-h cold incubation/3h rewarming >65% for all solutions); three solutions even enhanced cold-induced injury. However, when the predominant iron-dependent mechanism was eliminated by the addition of iron chelators, all preservation solutions yielded hepatocyte protection that was clearly superior to the one obtainable in cell culture medium or Krebs-Henseleit buffer with iron chelators (LDH release after 24-h cold incubation/3h rewarming 相似文献
944.
盆栽条件下暗褐网柄牛肝菌人工菌塘及其子实体的培养 总被引:1,自引:0,他引:1
在土壤中添加促进暗褐网柄牛肝菌(Phlebopus portentosus)菌丝及其宿主咖啡生长的营养液,用暗褐网柄牛肝菌纯培养种接种盆栽件下的咖啡苗根系,结果表明:92.5%以上的小粒咖啡(Coffea arabica)苗形成菌根,菌根上外延菌丝向根尖、侧根及根系周围的土壤延伸生长,与土粒相互交结形成菌塘。接种20天后,菌塘中子实体紧贴咖啡苗茎基或于咖啡苗株间生长,共生长162个子实体,发育成熟52个。子实体菌柄基部菌索与咖啡苗主根表面菌套连接。 相似文献
945.
In this article we construct Lyapunov functions for models described by piecewise-continuous and independent differential
equations. Because these models are described by discontinuous differential equations, the theory of Lyapunov functions for
smooth dynamical systems is not applicable. Instead, we use a geometrical approach to construct a Lyapunov function. Then
we apply the general approach to analyze population dynamics describing exploitative competition of two species in a two-patch
environment. We prove that for any biologically meaningful parameter combination the model has a globally stable equilibrium
and we analyze this equilibrium with respect to parameters.
相似文献
946.
In this paper, we propose an iterative learning rule that allows the imprinting of correlated oscillatory patterns in a model of the hippocampus able to work as an associative memory for oscillatory spatio-temporal patterns. We analyze the dynamics in the Fourier domain, showing how the network selectively amplify or distort the Fourier components of the input, in a manner which depends on the imprinted patterns. We also prove that the proposed iterative local rule converges to the pseudo-inverse rule generalized to oscillatory patterns. 相似文献
947.
A pot experiment was conducted in a growth chamber to investigate the effects of dandelion (Taraxacum officinale) and quackgrass (Elymus repens) on the growth of hybrid poplar (Populus deltoides × Populus × petrowskyana var. Walker). Single hybrid poplar seedlings were grown in pots either alone (SHP) or with four or eight dandelion plants
per pot or with one or three quackgrass plants per pot in two soils collected from sites previously managed for alfalfa and
pasture near Meadow Lake, Saskatchewan, Canada. Hybrid poplar and weed species were harvested approximately 7 and 14 weeks
after planting. Approximately 14 weeks after planting, hybrid poplar shoot biomass in the SHP treatment was 28 g for the pasture
soil and 22 g for the alfalfa soil. Corresponding shoot biomass for hybrid poplar grown with the dandelion and quackgrass
treatments varied from 0.54 to 0.81 g and 0.3 to 3.66 g, respectively. Other hybrid poplar growth parameters including stem
height, root collar diameter and fresh root biomass were similarly reduced by competition with the weed species. During the
growing period, soil solution N and K concentrations decreased several-fold in both soils; however, the magnitude of decrease
was comparatively higher in the weed treatments. Nitrogen, P and K uptake by hybrid poplar was greater in the SHP treatment
in both the soils (337–425, 38–49 and 396–463 mg pot−1, respectively) compared to the weed treatments (4–28, 0.4–6.2 and 0.6–54.0 mg pot−1, respectively) by the end of the experiment. The presence of quackgrass and dandelion severely affects the growth of hybrid
poplar by causing intense below-ground competition for nutrients.
Responsible Editor: Ismael Cakmak. 相似文献
948.
Ronnie O. Frederick Miyoshi Haruta Marco Tonelli Woonghee Lee Gabriel Cornilescu Claudia C. Cornilescu Michael R. Sussman John L. Markley 《Protein science : a publication of the Protein Society》2019,28(6):1115-1126
We report the recombinant preparation from Escherichia coli cells of samples of two closely related, small, secreted cysteine‐rich plant peptides: rapid alkalinization factor 1 (RALF1) and rapid alkalinization factor 8 (RALF8). Purified samples of the native sequence of RALF8 exhibited well‐resolved nuclear magnetic resonance (NMR) spectra and also biological activity through interaction with a plant receptor kinase, cytoplasmic calcium mobilization, and in vivo root growth suppression. By contrast, RALF1 could only be isolated from inclusion bodies as a construct containing an N‐terminal His‐tag; its poorly resolved NMR spectrum was indicative of aggregation. We prepared samples of the RALF8 peptide labeled with 15N and 13C for NMR analysis and obtained near complete 1H, 13C, and 15N NMR assignments; determined the disulfide pairing of its four cysteine residues; and examined its solution structure. RALF8 is mostly disordered except for the two loops spanned by each of its two disulfide bridges. 相似文献
949.
950.
目的:定量探究1%~80%酒精任氏液对蛙坐骨神经干双相复合动作电位(AP)的作用及其恢复情况。方法:制备长为6~8 cm的蛙坐骨神经干标本,分别将含有0%、1%、2%、4%、8%、16%、32%、48%、64%、80%酒精的标准任氏液通过新加装在神经屏蔽盒中的加药液槽浸泡位于刺激电极和接地电极之间的神经干各5 min,用BL-420F系统分别记录由刺激所诱发的双相AP;之后用标准任氏液冲洗5遍,浸泡5 min, 分别记录冲洗后AP。结果:与标准任氏液相比, ≤4%酒精任氏液对AP峰值和传导速度无影响,≥8%酒精任氏液作用后可使AP峰值和传导速度均下降;16%、32%和≥48%酒精任氏液作用后分别使神经干失去产生AP能力的比例为30%、90%和100%。≤32%酒精任氏液作用后冲洗,AP峰值可完全恢复;48%、64%和80%酒精任氏液作用后冲洗,能恢复产生动作电位能力的比例分别为90%、40%和0%,平均峰值分别下降至正常的60%、36%和0%;冲洗后: ≤8%酒精任氏液作用后的AP速度与正常无异,≥16%酒精任氏液作用后的AP速度无法完全恢复。结论:不同浓度酒精对AP峰值和传导速度影响不同,这对酒精的合理使用及过度使用后的损伤恢复有参考意义。 相似文献