天然珍珠母液及其配方产品实验结果的分析

目的研究分析天然珍珠母液中主要的微量化学成分及其配方产品。方法采用《中华人民共和国国家标准》中的食品氨基酸、牛磺酸和微量元素及化妆品的测定方法进行检测。结果天然珍珠母液富含人体所需的氨基酸、牛磺酸和多种微量元素,具有无致病菌及重金属不超标和产品获得认证的特点。结论天然珍珠母液有潜在的多领域应用和综合开发价值。     

EVALUATION OF MICRODIETS VERSUS FROZEN COPEPODSON GROWTH, SURVIVAL AND SELECTED CHEMICALCOMPOSITION OF LARGE YELLOW CROAKERPSEUDOSCIAENA CROCEA LARVAE

Three newly developed microdiets (MDs: Diet 1, Diet 2 and Diet 3), one co–feeding diet (Diet 4, combinedDiet 3 with frozen copepods) and frozen copepods (Diet 5) were tested for weaning large yellow croaker (Pseudosciaenacrocea) larvae from 25 to 60 days after hatching (DAH). The highest final specific growth rate (SGR, 7.97%/d) and sur-vival (40.0%) were observed in fish fed Diet 1, while those were the lowest in fish fed Diet 5 (4.15%/d and 20.4%, re-spectively). The survival of larvae fed Diet 4 showed no significant difference (P>0.05) from that of larvae fed Diet 1.However, SGR of larvae fed Diet 4 was significantly lower (P<0.05) than that of larvae fed Diet 1. Among the MDs,Diet 1 was proved to be superior to Diet 2 and Diet 3 for both SGR and survival. For all treatments, biomass in each tankwas observed a similar trend as SGR. Whole-body protein was not significantly different (P>0.05) among fish fed theMDs, which was lower than that of fish fed Diet 4, but higher than that of fish fed Diet 5. Fish fed the MDs had signifi-cantly higher (P<0.05) lipid deposition (10.6%—13.3%) than fish fed either Diet 4 (7.6%) or Diet 5 (7.2%). DietaryC20:4n-6 (AA) level was significantly lower (P<0.05) in Diet 5 than that in the MDs. However, the AA level was sig-nificantly higher (P<0.05) in fish fed either Diet 4 or Diet 5 than that in fish fed the MDs. The exceeded C22:6n-3 (DHA)levels in fish compared to their corresponding diets were found in those fed either Diet 4 or Diet 5. Inversely, C20:5n-3(EPA) and DHA levels decreased in fish fed the MDs relative to their proportions in MDs. These results showed that fishfed either Diet 4 or Diet 5 had higher efficiency of AA, DHA and EPA deposition than fish fed the MDs. This study sug-gested that large yellow croaker larvae could be successfully weaned by MD. Future research should be based on for-mula of Diet 1, since it was superior to Diet 2 and Diet 3. In addition, changes of digestive enzymes and digestive tractof large yellow croaker larvae fed different diets need to be investigated for an overall evaluation.     

2,5-Hexanedione Alters Elemental Composition and Water Content of Rat Peripheral Nerve Myelinated Axons

Abstract: Effects of 2,5-hexanedione on elemental concentrations and water content of peripheral nerve myelinated axons were determined using electron probe x-ray microanalysis. Axons (small, medium, and large) were analyzed in unfixed cryosections from rat tibial and proximal sciatic nerve samples. Animals were intoxicated with 2,5-hexanedione by two dosing paradigms: intraperitoneal or oral. Regardless of the route of exposure, internodal axoplasm of small and medium axons from both nerve regions exhibited selective, progressive reductions in dry weight K concentrations and water content. When calculated on a wet weight basis, K levels were comparable to or slightly above control values in tibial nerve, whereas in sciatic nerve, small transient decreases in wet weight K were evident. These changes in K and water correlated with the development of axonal atrophy. The wet and dry weight internodal elemental changes reported here do not suggest a metabolic or axolemmal defect, but rather imply a homeostatic response possibly related to the process of axonal atrophy. Giant axonal swellings were primarily associated with oral 2,5-hexane-dione intoxication, and corresponding analyses revealed few changes in element or water content compared with control. The absence of significant alterations in these swellings is consistent with mechanical expansion of the axon probably as a function of accumulating neurofilaments.     

Identification of small molecule proliferating cell nuclear antigen (PCNA) inhibitor that disrupts interactions with PIP-box proteins and inhibits DNA replication

We have discovered that 3,3′,5-triiodothyronine (T3) inhibits binding of a PIP-box sequence peptide to proliferating cell nuclear antigen (PCNA) protein by competing for the same binding site, as evidenced by the co-crystal structure of the PCNA-T3 complex at 2.1 Å resolution. Based on this observation, we have designed a novel, non-peptide small molecule PCNA inhibitor, T2 amino alcohol (T2AA), a T3 derivative that lacks thyroid hormone activity. T2AA inhibited interaction of PCNA/PIP-box peptide with an IC₅₀ of ∼1 μm and also PCNA and full-length p21 protein, the tightest PCNA ligand protein known to date. T2AA abolished interaction of PCNA and DNA polymerase δ in cellular chromatin. De novo DNA synthesis was inhibited by T2AA, and the cells were arrested in S-phase. T2AA inhibited growth of cancer cells with induction of early apoptosis. Concurrently, Chk1 and RPA32 in the chromatin are phosphorylated, suggesting that T2AA causes DNA replication stress by stalling DNA replication forks. T2AA significantly inhibited translesion DNA synthesis on a cisplatin-cross-linked template in cells. When cells were treated with a combination of cisplatin and T2AA, a significant increase in phospho(Ser¹³⁹)histone H2AX induction and cell growth inhibition was observed.     

Characterization of gamma-aminobutyric acid-benzodiazepine receptor complexes by protection against inactivation by group-specific reagents

Abstract: The chemical topography of the γ-aminobutyric acid (GABA) and benzodiazepine (BZ) receptors was investigated in a thoroughly washed cortical membrane preparation of the rat. Chemical modification by several amino- and tyrosyl-selective reagents and the protection from it by direct and allosteric ligands of the GABA-BZ receptor complex were used to identify the residues at the binding sites. Inhibition of specific GABA binding by p -diazobenzenesulfonic acid (DSA), tetrani-tromethane (TNM), and N -acetylimidazole and the selective and complete protection from it by GABA and muscimol suggest the presence of a tyrosine residue at the GABA_A site. TNM, like DSA, selectively decreased the number of the low-affinity GABA receptors, and this could be completely protected only by GABA concentrations that can saturate the low-affinity sites. TNM pre-treatment also abolished the muscimol enhancement of [³H]diazepam binding, which suggests that the low-affinity GABA receptor sites are responsible for this enhancement. Inhibition of GABA binding by pyridoxal-5-phosphate (PLP) and the selective protection by GABA and muscimol support the presence of a lysine residue at the GABA_A receptor site. Complete and selective protection from diethylpyrocarbonate (DEP) inhibition of [³H]diazepam binding by flurazepam suggests the presence of a histidine residue at the BZ site. Flurazepam selectively protected from inhibition of [³H]diazepam binding by N -bromosuccinimide and N -acetylimidazole, but not that by DSA and TNM, which does not allow a unanimous conclusion regarding the presence of tyrosine or tryptophan residues at the BZ site.     

DNBS/TNBS Colitis Models: Providing Insights Into Inflammatory Bowel Disease and Effects of Dietary Fat

Inflammatory Bowel Diseases (IBD), including Crohn''s Disease and Ulcerative Colitis, have long been associated with a genetic basis, and more recently host immune responses to microbial and environmental agents. Dinitrobenzene sulfonic acid (DNBS)-induced colitis allows one to study the pathogenesis of IBD associated environmental triggers such as stress and diet, the effects of potential therapies, and the mechanisms underlying intestinal inflammation and mucosal injury. In this paper, we investigated the effects of dietary n-3 and n-6 fatty acids on the colonic mucosal inflammatory response to DNBS-induced colitis in rats. All rats were fed identical diets with the exception of different types of fatty acids [safflower oil (SO), canola oil (CO), or fish oil (FO)] for three weeks prior to exposure to intrarectal DNBS. Control rats given intrarectal ethanol continued gaining weight over the 5 day study, whereas, DNBS-treated rats fed lipid diets all lost weight with FO and CO fed rats demonstrating significant weight loss by 48 hr and rats fed SO by 72 hr. Weight gain resumed after 72 hr post DNBS, and by 5 days post DNBS, the FO group had a higher body weight than SO or CO groups. Colonic sections collected 5 days post DNBS-treatment showed focal ulceration, crypt destruction, goblet cell depletion, and mucosal infiltration of both acute and chronic inflammatory cells that differed in severity among diet groups. The SO fed group showed the most severe damage followed by the CO, and FO fed groups that showed the mildest degree of tissue injury. Similarly, colonic myeloperoxidase (MPO) activity, a marker of neutrophil activity was significantly higher in SO followed by CO fed rats, with FO fed rats having significantly lower MPO activity. These results demonstrate the use of DNBS-induced colitis, as outlined in this protocol, to determine the impact of diet in the pathogenesis of IBD.     

Deciphering a Molecular Mechanism of Neonatal Diabetes Mellitus by the Chemical Synthesis of a Protein Diastereomer, [d-AlaB8]Human Proinsulin

Misfolding of proinsulin variants in the pancreatic β-cell, a monogenic cause of permanent neonatal-onset diabetes mellitus, provides a model for a disease of protein toxicity. A hot spot for such clinical mutations is found at position B8, conserved as glycine within the vertebrate insulin superfamily. We set out to investigate the molecular basis of the aberrant properties of a proinsulin clinical mutant in which residue Gly^B8 is replaced by Ser^B8. Modular total chemical synthesis was used to prepare the wild-type [Gly^B8]proinsulin molecule and three analogs: [d-Ala^B8]proinsulin, [l-Ala^B8]proinsulin, and the clinical mutant [l-Ser^B8]proinsulin. The protein diastereomer [d-Ala^B8]proinsulin produced higher folding yields at all pH values compared with the wild-type proinsulin and the other two analogs, but showed only very weak binding to the insulin receptor. The clinical mutant [l-Ser^B8]proinsulin impaired folding at pH 7.5 even in the presence of protein-disulfide isomerase. Surprisingly, although [l-Ser^B8]proinsulin did not fold well under the physiological conditions investigated, once folded the [l-Ser^B8]proinsulin protein molecule bound to the insulin receptor more effectively than wild-type proinsulin. Such paradoxical gain of function (not pertinent in vivo due to impaired secretion of the mutant insulin) presumably reflects induced fit in the native mechanism of hormone-receptor engagement. This work provides insight into the molecular mechanism of a clinical mutation in the insulin gene associated with diabetes mellitus. These results dramatically illustrate the power of total protein synthesis, as enabled by modern chemical ligation methods, for the investigation of protein folding and misfolding.     

山茱英的化学、药理及开发应用研究进展

本文就有关山茱萸中的挥发性成分、环烯醚萜苷、鞣质、有机酸等化学成分,山茱萸的抗菌消炎、调节免疫、降血糖、保肝、抗癌、抗休克、抗氧化、抗艾滋病等药理作用,以及国内外开发应用状况进行了文献综述,并对山茱萸的基础研究和进一步开发利用提出建议。     

施用沼肥对烤烟生长发育和生理特性以及烟叶化学成分的影响

通过田间试验和实验室检测研究了沼肥发酵原料配方,并就发酵后的沼肥对烤烟生长发育、生理特性和化学成分的影响进行了探索。结果表明,比较5种沼肥发酵的原料配方以A3处理最适宜沼肥种烟;在烤烟生长过程中施用沼肥,能促进烤烟早生快发,茎干显著变粗,叶面积显著变大,干物质积累也显著增加,同时,沼肥能使烟叶中硝酸还原酶和蔗糖转化酶活性提高,促进烟株的碳氮代谢,从而增加烤烟生产的产量和产值。沼肥对烤后烟叶的化学成分影响也较大,总糖、还原糖和钾等成分含量增加,烟碱含量降低。比较4种沼肥处理对烤烟的影响,B2处理效果最明显。     

咖啡化学成分及其生物活性研究进展

咖啡为茜草科(Rubiaceae)咖啡属(Coffea)植物,位居世界三大饮品之首,具有降低血糖、保护肝脏和神经保护等作用.咖啡化学成分类别较多,包括生物碱、酚酸类、黄酮类、萜类等.咖啡中的化学成分是发挥其生物学功能和形成特色风味的基础,对其化学成分来源和生物活性进行综述,为进一步发展咖啡产业提供依据和理论支撑.