The effect of high buffer cardioplegia and secondary cardioplegia on cardiac preservation and postischemic functional recovery: a 31P NMR and functional study in Langendorff perfused pig hearts.

High buffer cardioplegia may provide protection against ischemic damage by reducing the extent of intracellular acidosis. Secondary cardioplegia may improve postischemic recovery by restoration of high energy phosphates, ionic gradients, and intracellular pH. To test these hypotheses, pig hearts were arrested with high buffer (150 mM MOPS) cardioplegia or modified St. Thomas' solution II and then kept ischemic at 12 degrees C for 8 h. High energy phosphates and intracellular pH were followed during the period of ischemia, using 31P nuclear magnetic resonance spectroscopy, and functional recovery was followed during reperfusion. The hearts arrested by high buffer cardioplegia showed significantly higher intracellular pH than hearts preserved with St. Thomas' solution, but there were no significant differences in high energy phosphates. There were no significant differences in functional recovery. We found, however, that secondary cardioplegia abolished ventricular fibrillation, and resulted in improved functional recovery after 8 h of ischemic preservation compared with the hearts reperfused with Krebs-Henseleit solution alone. Our results suggest that despite attenuating the decreases in intracellular pH, high buffer cardioplegia does not improve recovery following 8 h of preservation at 12 degrees C. Secondary cardioplegia reduces the incidence of ventricular fibrillation and improves postischemic functional recovery of the myocardium.     

Enthalpic and entropic contributions to actin stability: calorimetry, circular dichroism, and fluorescence study and effects of calcium

The delta H associated with the thermal unfolding of G-actin has been determined by differential scanning calorimetry (DSC) to be 142 +/- 5 kcal/mol, with the Tm (melting temperature) at 57.2 +/- 0.5 degrees C, at pH 8.0 (heating rate 0.5 K/min). The transition is broad and cannot be treated as a single transition that mimics a two-state process, suggesting the existence of domains. Deconvolution is done to fit it into two quasi-independent two-state transitions. For F-actin, the transition is more cooperative, with a cooperative ratio (the ratio of van't Hoff enthalpy and calorimetric enthalpy) of 1.4, indicating intermonomer interaction. The delta H of the thermal unfolding of F-actin is 162 +/- 10 kcal/mol with a Tm at 67.0 +/- 0.5 degrees C. A state of G-actin similar to that of the heat-denatured form, designated D-actin, is obtained by removing tightly bound Ca2+ with EGTA. The DSC-detectable cooperative transition is completely lost when the free calcium concentration of the medium is 1 x 10(-11) M or lower, using a Ca2+/EGTA buffer system. However, circular dichroism (CD) shows that the helix content of actin, 32% in the G-form, is only partially reduced to 19% in this apo form. The CD spectrum and the helix content of the calcium-depleted actin are almost identical with those of the heat-denatured D form. This loss of 40% of the native helical content is irreversible in both cases. The remaining 60% of the native helical content cannot be further eliminated by heating to 95 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)     

JQ-1 ameliorates schistosomiasis liver granuloma in mice by suppressing male and female reproductive systems and egg development of Schistosoma japonicum

Schistosomiasis is a serious and widespread parasitic disease caused by infection with Schistosoma. Because the parasite’s eggs are primarily responsible for schistosomiasis dissemination and pathogenesis, inhibiting egg production is a potential approach to control the spread and severity of the disease. The bromodomain and extra-terminal (BET) proteins represent promising targets for the development of epigenetic drugs against Schistosoma. JQ-1 is a selective inhibitor of the BET protein family. In the present study, JQ-1 was applied to S. japonicum in vitro. By using laser confocal scanning microscopy and EdU incorporation assays, we showed that application of JQ-1 to worms in vitro affected egg laying and the development of both the male and female reproductive systems. JQ-1 also inhibited the expression of the reproductive-related genes SjPlk1 and SjNanos1 in S. japonicum. Mice infected with S. japonicum were treated with JQ-1 during egg granuloma formation. JQ-1 treatment significantly reduced the size of the liver granulomas and levels of serum alanine aminotransferase and aspartate aminotransferase in mice and suppressed both egg laying and the development of male and female S. japonicum reproductive systems in vivo. Moreover, the mRNA expression levels of some proinflammatory cytokines were decreased in the parasites. Our findings suggest that JQ-1 treatment attenuates S. japonicum egg–induced hepatic granuloma due at least in part to suppressing the development of the reproductive system and egg production of S. japonicum. These findings further suggest that JQ-1 or other BET inhibitors warrant additional study as a new approach for the treatment or prevention of schistosomiasis.     

早产儿语言发展的影响因素及其干预对策

早产儿的语言发展受到多种因素的影响,可能导致他们在词汇、语法、语音等方面出现发展滞后或障碍。本文首先简述了影响早产儿语言发展的生物学和环境因素的研究进展,其中生物学因素包括早产程度、体重和性别、新生儿发病率和疾病严重程度等,环境因素则包括新生儿重症监护室的环境、家庭中的语言环境和社会因素等。在明确这些影响因素的基础上,本文强调了早期评估和早期干预是优化早产儿语言发育效果的关键步骤,并分析了具体的干预对策,例如生理和神经干预、优化新生儿重症监护室（NICU）环境、增强家庭语言互动、多学科合作和社会支持等。此综述旨在探讨影响早产儿语言发展的各种因素,并总结出有效的早期干预措施,为其提供更为全面的语言发展支持。     

Cryo-EM structure of the fatty acid reductase LuxC–LuxE complex provides insights into bacterial bioluminescence

The discovery of reduced flavin mononucleotide and fatty aldehydes as essential factors of light emission facilitated study of bacterial luminescence. Although the molecular mechanisms underlying bacterial luminescence have been studied for more than 60 years, the structure of the bacterial fatty acid reductase complex remains unclear. Here, we report the cryo-EM structure of the Photobacterium phosphoreum fatty acid reductase complex LuxC–LuxE to a resolution of 2.79 Å. We show that the active site Lys238/Arg355 pair of LuxE is >30 Å from the active site Cys296 of LuxC, implying that catalysis relies on a large conformational change. Furthermore, mutagenesis and biochemical experiments support that the L-shaped cleft inside LuxC plays an important role in substrate binding and reaction. We obtained a series of mutants with significantly improved activity as measured by in vitro bioluminescence assays and demonstrated that the double mutant W111A/F483K displayed the highest activity (370% of the WT). Our results indicated that the activity of LuxC significantly affects the bacterial bioluminescence reaction. Finally, we expressed this mutated lux operon in Escherichia coli but observed that the in vivo concentrations of ATP and NADPH limited the enzyme activity; thus, we conclude that the luminous intensity mainly depends on the level of metabolic energy.     

有关彩色真菌培养基的应用

彩色真菌培养基具有选择性强、分辨率高、易生长、易观察的特点。在真菌培养方面优于其它培养基,其主要作用机理在于应用了化学生物效应促进真菌生长。     

基于景感生态学理念的乡村社会-生态系统供给服务研究

乡村社会-生态系统的稳定和可持续发展为农业农村现代化的实现奠定着基础,在稳定社会经济发展、提高城乡居民福祉方面发挥着重要作用。服务性公共设施作为乡村社会-生态系统供给服务的重要组成部分,代表了乡村的发展水平与该地区居民生活质量水平。研究公共服务设施的空间分布特征和综合评价其供给服务可改善乡村社会-生态系统结构,为城乡居民提供高质量的社会生态系统服务。以厦门市岛外城市化乡村为研究对象,通过厦门市岛外POI数据和乡村社会经济统计数据,以公共服务设施为景感载体,分析其空间分布和测度其供给服务水平,采用核密度分析方法与熵值分析法,分析厦门市乡村社会-生态系统供给服务空间分布特征,结合人口、经济、距岛内核心区距离等指标对各村庄社会-生态系统供给服务能力进行皮尔逊相关性分析。研究发现厦门乡村公共设施供给服务能力表现为集美区 > 海沧区 > 同安区 > 翔安区;各村庄公共设施供给服务能力水平影响因素是多元且具有多样性的;提出从城乡居民的认知心理与物质需求出发对公共设施进行景感生态营造以提高村庄社会-生态系统供给服务能力,更好满足人们的需求。本文对公共服务设施的空间优化提出对策建议,研究结果可为乡村社会-生态系统供给服务提升和乡村可持续发展提供理论研究依据。     

Response of physiologic metabolism and cell structures in mango fruit to exogenous methyl salicylate under low-temperature stress

We explored the effects of exogenous methyl salicylate (MeSA) on the development of chilling injury symptom, and the structure and composition of the pericarp, in mango ( Mangifera indica L. cv. 'Red 6') fruit under low-temperature stress using histochemical analysis and scanning electron microscopy together with Fourier transform infrared (FTIR) analysis. The results indicated that chilling injury symptom was remarkably limited in the fruit treated with MeSA at 0.1 m M as compared to the 5°C control, demonstrating the positive effects of MeSA in reducing chilling injury of mango fruit in low-temperature storage. In MeSA-treated fruit, the pericarp wax surface showed many cracks, and exocarp cells exhibited normal separation. The cell wall of exocarp contained lower amounts of pectic substances, aliphatics and phenolics in MeSA-treated fruit. In addition, MeSA-treated fruit contained more esterified substances and less carboxylate and carboxyl substances. Our work revealed the importance of MeSA in enhancing fruit tolerance to low-temperature stress and suggested a contribution of cellular structure and composition to this effect, which has not been reported previously.     

流行性出血热地鼠肾细胞灭活疫苗人体试用细胞免疫反应观察

观察了20位志愿者在接种试验性流行性出血热(EHF)地鼠肾细胞(GHKC)双价灭活疫苗后的细胞免疫反应,并以其体液免疫反应作对照观察。用淋巴细胞转化试验测定细胞免疫水平。结果首针疫苗接种后42天和56天,特异性刺激指数(SSI)和非特异性刺激指数(NSI)均较免疫前显著增高(P_(SSI)<0.001;P_(NSI)<0.02),免疫后SSI累计阳转率为100％,NSI累计阳转率为60％,免疫后6个月二者均降低至正常水平。免疫后56天测定抗体,荧光抗体阳转率为100％;微量感染性中和试验表明,针对家鼠型病毒L99株中和抗体阳转率为95％,而针对野鼠型病毒JR株阳转率为65％。