烟酰胺抑制人皮黑素细胞的适宜浓度研究

研究了烟酰胺对酪氨酸酶活性、人皮黑素细胞的增殖率、细胞周期动力学和黑素合成的影响。结果显示：烟酰胺体外抑制酪氨酸酶活性不明显；随浓度增加、作用时间的延长，烟酰胺抑制黑素细胞的增殖作用明显；0．25g／L烟酰胺加入24h后，细胞增殖指数明显下降，细胞多处于G0-G1期，S期细胞数量也显减少。实验发现：0．25g／L以上的烟酰胺均可以抑制黑素细胞中黑素合成，其中0．25g／L的烟酰胺可抑制黑素合成且对细胞损伤作用最小。故推荐0．25g／L的烟酰胺为安全、有效作用浓度。     

TOCOPHEROLS AND PHOSPHOLIPIDS ENHANCE THE OXIDATIVE STABILITY OF BORAGE AND EVENING PRIMROSE TRIACYLGLYCEROLS

The effect of individual phospholipids and tocopherols as well as their combinations on the oxidative stability of borage and evening primrose triacylglycerols (TAG) was investigated. Based on conjugated dienes (CD) and 2-thiobarbituric acid reactive substances (TBARS) formed in borage and evening primrose TAG, the antioxidant effectiveness of phosphatidylcholine (PC), was higher than that of phosphotidylethanolamine (PE) in borage TAG while the reverse was observed for evening primrose TAG. Meanwhile, a synergistic effect between tocopherols and phospholipids in both borage and evening primrose TAG was noted. The most effective combination in borage TAG was that of PC and α-tocopherol, while PE with α-tocopherol exerted the best effects in evening primrose TAG. Therefore, the antioxidant effectiveness of phospholipids may vary depending on their fatty acid composition, nature of the functional groups and the chemical composition of the lipid system in which they are examined. The results also demonstrate the importance of minor components of vegetable oils on their oxidative stability.     

压力对消泡器消泡能力的影响实验研究与数值模拟

泡沫钻进中,消泡有十分重要的环保和经济意义。但在实际生产中,现有的消泡器不能很好地达到消泡的要求,这就需要对消泡器做更进一步的深入研究。通过建立消泡器室内试验台,进行压力对消泡能力影响的试验,确定了压力与消泡率的关系,同时利用FLUENT软件中的VOF模型对泡沫在消泡器中流动时压力变化进行了数值模拟,模拟结果与实验结果是相符的。     

超声脉冲反射法和激光吸收光谱法同步测量流动液膜厚度

液膜流动现象在工业过程中广泛存在,对流动液膜厚度测量方法的测量研究至关重要。首先利用已知液膜厚度的标准具（100～1000 μm）对超声脉冲反射法和激光吸收光谱法精度进行验证;结果表明,超声脉冲反射法测量液膜厚度的平均测量误差为1.07%,激光吸收光谱法测量液膜厚度的平均测量误差为1.29%。同时结合两种方法对流动液膜进行研究,结果表明,当液膜在低速/中速/高速流动时,两种方法测量流动液膜的平均厚度吻合良好,平均厚度差值分别为16.59、16.26、13.36 μm,流动液膜厚度的标准方差的相对偏差分别为0.29%、7.71%、25.37%,且在三种不同速度下两种方法测得在1s的周期内液膜波动次数一致。     

Molecular characterization of sweet potato (<i>Ipomoea batatas</i> [L.] Lam) germplasms for desirable traits by using simple sequence repeats markers

Every breeding program that aims to create new and improved cultivars with desired traits mostly relies oninformation related to genetic diversity. Therefore, molecular characterization of germplasms is important to obtain targetcultivars with desirable traits. Sweet potato [Ipomoea batatas (L.) Lam] is widely considered the world’s most important crop,with great diversity in morphological and phenotypic traits. The genetic diversity of 20 sweet potato germplasms originatingfrom Bangladesh, CIP, Philippines, Taiwan, and Malaysia were compared, which was accomplished by genetic diversityanalysis by exploring 20 microsatellite DNA markers for germplasm characterization and utilization. This information waseffective in differentiating or clustering the sweet potato genotypes. A total of 64 alleles were generated using the 20 primersthroughout the 20 germplasm samples, with locus IBS97 having the highest number of alleles (5), whereas locus IbU33 hadthe fewest alleles (2). The alleles varied in size from 105 (IbU31) to 213 base pairs (IBS34). The Polymorphism InformationContent (PIC) values for the loci IbL46 and IBS97 varied from 0.445 to 0.730. IBS97 has the highest number of effectivealleles (3.704), compared to an average of 2.520. The average Shannon’s diversity index (H) was 1.003, ranging from 0.673 inIbU3 to 1.432 in IBS97. The value of gene flow (Nm) varied between 0.000 and 0.005, with an average of 0.003, whereasgenetic differentiation (FST-values) ranged between 0.901 and 1.000. The sweet potato germplasm included in this study hada broad genetic base. SP1 vs. SP9 and SP12 vs. SP18 germplasm pairings had the greatest genetic distance (GD = 0.965),while SP1 vs. SP2 germplasm couples had the least genetic diversity (GD = 0.093). Twenty genotypes were classified into twogroups in the UPGMA dendrogram, with 16 genotypes classified as group “A” and the remaining four genotypes, SP10,SP18, SP19, and SP20, classified as group “B.” According to cluster analysis, the anticipated heterozygosity (gene diversity) ofNei (1973) was 0.591 on average. In summary, SSR markers successfully evaluated the genetic relationships among the sweetpotato accessions used and generated a high level of polymorphism. The results of the present study will be useful for themanagement of germplasm, improvement of the current breeding strategies, and the release of new cultivars as varieties.     

The role of 5′-adenosine monophosphate-activated protein kinase (AMPK) in skeletal muscle atrophy

As a key coordinator of metabolism, AMP-activated protein kinase (AMPK) is vitally involved in skeletal muscle maintenance. AMPK exerts its cellular effects through its function as a serine/threonine protein kinase by regulating many downstream targets and plays important roles in the development and growth of skeletal muscle. AMPK is activated by phosphorylation and exerts its function as a kinase in many processes, including synthesis and degradation of proteins, mitochondrial biogenesis, glucose uptake, and fatty acid and cholesterol metabolism. Skeletal muscle atrophy is a result of various diseases or disorders and is characterized by a decrease in muscle mass. The pathogenesis and therapeutic strategies of skeletal muscle atrophy are still under investigation. In this review, we discuss the role of AMPK in skeletal muscle metabolism and atrophy. We also discuss targeting AMPK for skeletal muscle treatment, including exercise, AMPK activators including 5-amino-4-imidazolecarboxamide ribonucleoside and metformin, and low-level lasers. These studies show the important roles of AMPK in regulating muscle metabolism and function; thus, the treatment of skeletal muscle atrophy needs to take into account the roles of AMPK.     

Biochemical association between the prevalence of genetic polymorphism and myocardial infarction

Genetic polymorphism has a vital role in the pathogenesis and development of myocardial infarction (MI). Single nucleotide polymorphism at any one of the amino acid sequences can result in a diseased state. A single gene can exhibit genetic polymorphism at more than one position giving rise to different variants. Genetic polymorphism of angiotensinogen (AGT) M235T, AGT T174M, and angiotensin-1-converting enzyme (ACE) I/D, endothelial nitric oxide synthase (eNOS), and methylenetetrahydrofolate reductase (MTHFR) can be a risk factor for MI. However, it is important to study the prevalence of genetic polymorphisms of these genes among different populations. MI is influenced by genetic polymorphism of various genes, including AGT, ACE, eNOS, MTHFR, etc. However, the association of genetic polymorphism of these genes varies among different populations, but different ethnic groups could show contradictory results. These genes have shown a positive association with risks of MI in some populations, whereas the results have not been consistent with every ethnic group. In this article, we have summarized the genetic variations in the aforementioned genes and their association with MI.