人骨髓间充质干细胞培养方法

骨髓间充质干细胞(BMMSCs)是一种多潜能的成体干细胞,在细胞治疗和组织工程上具有广阔的应用前景。对供体年龄、分离方法、培养密度、培养基和培养基质表面性质对细胞增殖的影响进行了比较,重点阐述了用人自体血清结合多种细胞因子,替代胎牛血清培养BMMSCs的效果,转染端粒酶基因的BMMSCs的增殖能力和分化潜能,以及灌注培养反应器用于大规模培养的技术进展。     

益生素研究和应用进展

益生素作为一种新的生物技术产品,具有无毒、无副作用,促进动物生长,提高饲料转化率,替代抗生素之优点,受到人们的关注。本文综述了益生素的特点、作用机制和应用效果,并预测其发展前景。     

细胞因子在动脉粥样硬化发病中的作用机制及相关治疗举措研究现状

动脉粥样硬化是一种慢性炎症性疾病,开展细胞因子相关研究为动脉粥样硬化的预防和治疗提供了重要方向。细胞因子由不同类型的细胞产生,作用于一系列靶点,在动脉粥样硬化的发病和进展过程中起关键作用。本文概述了动脉粥样硬化有关的主要促炎和抗炎细胞因子及其作用机制,归纳了现阶段有关动脉粥样硬化细胞因子的针对性治疗措施,并对细胞因子在动脉粥样硬化防治方面的研究和治疗前景进行展望。     

益生素研究的应用进展

益生素作为一种新的生物技术产品,具有无毒、无副作用,促进动物生长,提高饲料转化率,替代抗生素之优点,人们的关注。本文综述了益生素的特点、作用机制和应用效果,并预测其发展前景。     

脱氢表雄酮调节炎性细胞因子作用的研究进展

炎症性疾病通常由过度或持续的炎症反应所引起。炎性细胞因子参与了炎症反应中的多个过程，如促进炎症细胞的聚集、诱导炎症介质的生成等。因此，控制炎性细胞因子的生成对炎症性疾病的治疗具有至关重要的作用。脱氢表雄酮(dehydroepiandrosterone,DHEA)是一种内源性类固醇激素。DHEA能调节炎性细胞因子的产生和释放，具有控制炎症反应的潜力。本文从DHEA的特征、调节炎性细胞因子的机制及临床应用前景进行综述，为临床治疗炎症性疾病提供新的思路和策略。     

干细胞因子及其受体在红系分化中的作用

干细胞因子作为一种多能细胞因子,在临床上有较好的应用前景。随着CD34^ 细胞分离培养技术的完善,干细胞因子及其受体在红系增殖、分化中的重要作用正逐渐被发现并阐述清楚,对临床上相关疾病的治疗有重要的指导意义。本介绍了干系胞因子及其配体抑制红系祖细胞凋亡和促进红系祖细胞增殖和分化的功能,以及在临床上的应用前景。     

亚麻油替代鱼油对杂交鲟生长、脂肪酸组成及脂肪代谢的影响

为研究亚麻油替代不同水平的鱼油后对杂交鲟(Acipenser baeri Brandt♀×A. schrenckii Brandt♂)幼鱼[初均重(70.8±0.5) g]生长、脂肪酸组成、肝脏及肌肉脂肪沉积以及脂肪代谢的影响, 在油脂添加量为8%的饲料中用亚麻油分别替代0(LO0)、25%(LO25)、50%(LO50)、75%(LO75)和100%(LO100)的鱼油, 配制5种等氮(38.7%CP)等脂(10%CF)饲料。每组饲料随机设3个重复, 养殖周期为12周。结果表明,亚麻油替代100%的鱼油对杂交鲟幼鱼的生长没有显著影响, 而且随着饲料中亚麻油含量的上升, 饲料效率有所提高, 100%鱼油替代组的饲料效率明显高于100%鱼油组的(P<0.05); 但用亚麻油替代鱼油后, 肌肉和肝脏的粗脂肪含量以及血清中谷草转氨酶、谷丙转氨酶和乳酸脱氢酶活性明显升高(P<0.05); 肌肉亚麻酸和n-3多不饱和脂肪酸的含量与饲料中相应脂肪酸组成呈明显的线性相关关系(R2>0.69; P<0.05)。对于杂交鲟的脂肪代谢而言, 亚麻油的添加对血清中的游离脂肪酸、甘油三酯、高、低密度脂蛋白胆固醇的变化产生明显影响, 但亚麻油对血清总胆固醇和酮体影响不显著。考虑到亚麻油完全替代鱼油后, 肌肉中的EPA和DHA这两种长链高不饱和脂肪酸的含量仅下降了不到30%, 因此亚麻油应该是一种比较优质的鱼油替代品。     

长效益生素菌株的筛选及生产工艺的初步研究

益生素是一种能够替代抗生素的绿色饲料添加剂。报道了通过对益生素菌种的初筛和复筛、菌株药敏实验、菌体吸附方法及产品的中试研究 ,确定了生产工艺 :采用筛选的地衣芽孢杆菌YS 0 2 ,在特定的培养基和培养条件下 18～ 2 2h ,通过 10 %CaCO3 吸附、过滤、干燥获得微生态制剂 ,其活菌数≥ 15 0亿 / g。实验证明 ,YS 0 2活菌制剂可替代抗生素防治动物习惯性腹泻。     

抗菌肽作为饲料添加剂的研究进展

抗菌肽是生物体抵抗外界病原体侵袭而产生的一类小分子活性多肽,是生物体内先天性防御系统的重要组成部分。抗生素污染问题是目前影响我国畜牧与水产养殖业可持续健康发展的重大科技问题,由此引起的养殖产品中违禁抗生素残留成为制约我国出口创汇和食品安全的瓶颈,饲料中大量添加抗生素是导致抗生素超标的主要原因之一。寻找能够替代抗生素的环保型饲料添加剂,研制出无抗生素的环境友好型饲料,是我国畜牧与水产养殖业健康发展的迫切需求。就抗菌肽的来源,不同功能以及作为饲料添加剂在养殖中的应用作一简要综述。。     

饲料鱼粉、菜粕比例对异育银鲫生长和饲料利用的影响

通过在饲料中配制不同鱼粉和菜粕比例,探讨利用菜粕蛋白替代鱼粉对异育银鲫（Carssius auratus gibelio）的生长和饲料利用的影响。饲料中菜粕蛋白替代鱼粉蛋白的比例分别为 0、20%、40%、60% 和80%。实验结果表明,当饲料中菜粕蛋白比例高于40%时,异育银鲫的生长显著下降（P0.05）,对摄食率影响不明显（P0.05）。在80%替代水平下,干物质和蛋白质的消化率最低,能量消化率在40%替代水平最低。饲料转化效率在20%蛋白替代后明显下降（P0.05）。蛋白质和能量储积率在40%蛋白替代后明显下降（P0.05）。在40%菜粕蛋白下,鱼体能量和脂肪含量最高。鱼体蛋白质在60% 和80% 菜粕蛋白时最低,脂肪在20% 菜粕蛋白时最高。因此饲料菜粕蛋白的水平不超过20%（干物质含量约17%）不会影响异育银鲫的生长和饲料转化。       

Chicken interleukin-6. cDNA structure and biological properties.

Suppression subtractive hybridization technology was used to identify differentially expressed genes in spleens of chickens that had been treated with the synthetic immune modifier S-28463. One induced chicken gene encoded a protein with about 35% sequence identity to human interleukin-6 (IL-6). It consists of 241 amino acids including a putative N-terminal signal peptide of 47 residues. Bacterially expressed chicken IL-6 (ChIL-6) carrying a histidine tag in place of the signal peptide was biologically active: it induced proliferation of the IL-6-dependent murine hybridoma cell line 7TD1. The concentration of ChIL-6 required for half-maximal proliferative response was approximately 60 pg.mL-1. When injected intravenously into adult chickens, purified recombinant ChIL-6 induced an increase in serum corticosterone levels. Supernatants of chicken LMH and monkey COS-7 cells transiently transfected with a ChIL-6 expression construct induced proliferation of 7TD1 cells, demonstrating that recombinant ChIL-6 from eukaryotic cells is also active.     

Role of immunostimulatory molecules in poultry vaccines

Immunization by vaccination is the most suitable and safest method for preventing infectious diseases in the poultry worldwide. Vaccines alone cannot effectively protect birds from variety of pathogens under field conditions. The combined use of potent immunostimulants in vaccines is an alternative to increase the efficacy of vaccines that can be achieved by the development of better adjuvant. One such adjuvant is cytokine; cytokines have been used extensively as adjuvant in vaccines and are responsible for the type and extent of an immune response following vaccination. Although the innate immune system in birds is not fully characterized but their immune system is very much similar to that of mammals, and moreover with the recent discovery of a number of avian cytokine genes it is now possible to study their effectiveness in enhancing the immune response during vaccination. This review focuses on the recent studies and developments involving the role of immunomodulating agents especially cytokines of avian origin in poultry vaccines.     

Excessive Cytokine Response to Rapid Proliferation of Highly Pathogenic Avian Influenza Viruses Leads to Fatal Systemic Capillary Leakage in Chickens

Highly pathogenic avian influenza viruses (HPAIVs) cause lethal infection in chickens. Severe cases of HPAIV infections have been also reported in mammals, including humans. In both mammals and birds, the relationship between host cytokine response to the infection with HPAIVs and lethal outcome has not been well understood. In the present study, the highly pathogenic avian influenza viruses A/turkey/Italy/4580/1999 (H7N1) (Ty/Italy) and A/chicken/Netherlands/2586/2003 (H7N7) (Ck/NL) and the low pathogenic avian influenza virus (LPAIV) A/chicken/Ibaraki/1/2005 (H5N2) (Ck/Ibaraki) were intranasally inoculated into chickens. Ty/Italy replicated more extensively than Ck/NL in systemic tissues of the chickens, especially in the brain, and induced excessive mRNA expression of inflammatory and antiviral cytokines (IFN-γ, IL-1β, IL-6, and IFN-α) in proportion to its proliferation. Using in situ hybridization, IL-6 mRNA was detected mainly in microglial nodules in the brain of the chickens infected with Ty/Italy. Capillary leakage assessed by Evans blue staining was observed in multiple organs, especially in the brains of the chickens infected with Ty/Italy, and was not observed in those infected with Ck/NL. In contrast, LPAIV caused only local infection in the chickens, with neither apparent cytokine expression nor capillary leakage in any tissue of the chickens. The present results indicate that an excessive cytokine response is induced by rapid and extensive proliferation of HPAIV and causes fatal multiple organ failure in chickens.     

The effects of macrophage-derived cytokines on lipid metabolism in chicken (Gallus domesticus) hepatocytes and adipocytes

1. The effects of avian and mammalian cytokines on avian lipid metabolism were compared using cultured chicken hepatocytes and adipocytes. 2. Conditioned medium from an endotoxin-stimulated chicken macrophage cell line was used as a source of chicken cytokines. Incubation of chicken adipocytes with conditioned medium greatly decreased their lipoprotein lipase activity. 3. Inhibition of lipoprotein lipase synthesis in similar experiments in mammals has been attributed to the effects of TNF-alpha and/or IL-1, but recombinant human TNF-alpha and IL-1 had no effect on lipoprotein lipase activity in chicken adipocytes. 4. Conditioned medium from chicken macrophages produced a 2-fold increase in lipogenesis in chicken adipocytes but had no effect on lipogenesis in chicken hepatocytes. 5. The results point to major differences between mammals and birds in the way that lipid metabolism responds to cytokines and provide further evidence that mammalian cytokines are ineffective in birds.     

Highly pathogenic avian influenza viruses do not inhibit interferon synthesis in infected chickens but can override the interferon-induced antiviral state

From infection studies with cultured chicken cells and experimental mammalian hosts, it is well known that influenza viruses use the nonstructural protein 1 (NS1) to suppress the synthesis of interferon (IFN). However, our current knowledge regarding the in vivo role of virus-encoded NS1 in chickens is much more limited. Here, we report that highly pathogenic avian influenza viruses of subtypes H5N1 and H7N7 lacking fully functional NS1 genes were attenuated in 5-week-old chickens. Surprisingly, in diseased birds infected with NS1 mutants, the IFN levels were not higher than in diseased birds infected with wild-type virus, suggesting that NS1 cannot suppress IFN gene expression in at least one cell population of infected chickens that produces large amounts of the cytokine in vivo. To address the question of why influenza viruses are highly pathogenic in chickens although they strongly activate the innate immune system, we determined whether recombinant chicken alpha interferon (IFN-α) can inhibit the growth of highly pathogenic avian influenza viruses in cultured chicken cells and whether it can ameliorate virus-induced disease in 5-week-old birds. We found that IFN treatment failed to confer substantial protection against challenge with highly pathogenic viruses, although it was effective against viruses with low pathogenic potential. Taken together, our data demonstrate that preventing the synthesis of IFN is not the primary role of the viral NS1 protein during infection of chickens. Our results further suggest that virus-induced IFN does not contribute substantially to resistance of chickens against highly pathogenic influenza viruses.     

The avian genome uncovered

Our knowledge of avian genomics has increased rapidly over the past few years, culminating in the recent publication of a draft sequence of the chicken genome, a milestone event in avian genetics and evolutionary biology. Comparative analysis reveals a compact avian genome structure containing a similar number of genes as found in mammals but with shorter intergenic DNA sequences and fewer repeats. Recombination is at a higher rate than in mammals, particularly for microchromosomes. These also differ from macrochromosomes in their GC and gene content, and their substitution rate. The avian genome has remained unusually stable during evolution and contrasts sharply with the frequent chromosomal rearrangements seen in the rodent lineage. Detailed analyses of polymorphism levels in chickens, including a genome-wide screening in three chicken breeds yielding a set of 2.8 million SNP markers, reveal unexpectedly high levels of genetic diversity. As a notable exception, the female-specific W chromosome is very low in diversity, a probable consequence of the effect of selection on non-recombining chromosomes. The chicken genome promises to be a useful resource for ecological and evolutionary studies of other bird species.     

Avian genomics and the innate immune response to viruses

Viral diseases pose a significant threat to the poultry industry. However, there is currently a lack of antivirals and suitable vaccine adjuvants available to the poultry industry to combat this problem. The innate immune system is now recognised to be essential in the response to viral infection. However, in contrast to mammals, the innate immune response in chickens is relatively uncharacterised. The release of the full chicken genome sequence has accelerated the identification of genes involved in the immune response. The characterisation of these genes, including Toll-like receptors and cytokines has led to the identification of potential alternate antivirals and adjuvants.     

The chicken genome contains no HMG1 retropseudogenes but a functional HMG1 gene with long introns

We have cloned the genomic sequence coding for the high mobility group 1 (HMG1) protein in chickens. Multiple sequence alignment shows that the chicken HMG1 gene is highly homologous to the human and the mouse HMG1 genes. The gene structure of chicken HMG1 is similar to that of the mouse and the human HMG1 genes, with the same exon-intron boundaries. However, in contrast to other avian genes that have shorter introns, the chicken HMG1 gene has introns that are twice as long as their mammalian homologues. In addition to the functional, intron-containing HMG1 gene, all mammalian genomes contain more than 50 copies of HMG1 retropseudogenes each, while in the chicken genome there are no HMG1 retropseudogenes. This finding suggests that the HMG1 retropseudogenes arose in mammals after their divergence away from the birds.