Growth hormone-releasing factor effects on pituitary function, growth, and lactation

Growth and lactation are complex processes controlled by several metabolic hormones such as insulin, glucagon, and thyroid hormones but most notably growth hormone. Growth hormone secretion is regulated by two hypothalamic hormones, somatostatin, an inhibitory regulatory factor, and growth hormone-releasing factor. The quantity and pattern of growth hormone secretion is ultimately regulated in concert by the secretion of both regulatory factors from the hypothalamus through the hypothalamo-hypophyseal portal system, where they exert their actions at unique pituitary receptors. Because the potential use of exogenous growth hormone administration for the stimulation of growth efficiency and lactation has been demonstrated, recent efforts have been directed toward the enhancement of production through manipulation of endogenous growth hormone secretion via its releasing factor. Thus far, releasing factor-stimulated growth and lactation has not been achieved to the same extent as that of exogenous growth hormone. Growth hormone-releasing factor has stimulated growth in two growth hormone-deficient children, as well as female, but not male, rats. Although all food-producing species tested to date respond to growth hormone-releasing factor with the appropriate growth hormone response, continuous or pulsatile administration of releasing factor has not resulted in increased growth rate in sheep, chicks, or hogs. Despite levels of circulating growth hormone that would be expected to produce a 30% increase in milk production if given exogenously to dairy cows, releasing factor-stimulated growth hormone secretion has resulted in only a 3 to 9% increase. It is clear from these studies that further developments are necessary to demonstrate the practical application of growth hormone-releasing factor.     

盐酸哈尔酚骆驼蓬碱对人肝癌细胞生长的影响与自噬诱导作用的研究

目的探讨低剂量盐酸哈尔酚骆驼蓬碱(harmol hydrochloride dihydrate,HHD)对肝癌细胞株HepG2生长的影响及其自噬诱导作用。方法用不同浓度的HHD作用于肝癌细胞株HepG2 24 h后四甲基偶氮唑盐(methyl thiazolyl tetrazolium, MTT)法检测细胞活力,用流式细胞仪检测细胞凋亡,用Hoechst和PI双重染色方法观察细胞凋亡,用蛋白质印迹(western blotting, WB)的方法检测LC-3Ⅱ表达水平。结果 MTT检测结果显示不同浓度的HHD作用于HepG2细胞24h后,细胞活力随HHD浓度升高而降低,差异均有统计学意义(P0.05)。0、0.005、0.01 mg/mL HHD作用于HepG2细胞24 h后,细胞凋亡率均明显高于空白对照组(P0.05)。0.01 mg/mL的HHD处理HepG2细胞24 h后,凋亡小体的形成明显增多(P0.05)。Western blotting法检测发现0.01 mg/mL HHD作用细胞24 h后自噬标记蛋白LC-3Ⅱ表达显著升高。结论 HHD抑制肝癌细胞株HepG2在体外生长,其诱导细胞自噬可能是抑制作用机制之一。     

奶山羊乳腺中胰岛素样生长因子及其受体的表达与作用

为研究胰岛素样生长因子及胰岛素样生长因子受体在奶山羊乳腺组织青春期、妊娠期、泌乳期及退化期表达的差异及变化,探索其在奶山羊乳腺发育过程中的作用,根据奶山羊乳腺发育特点及生长阶段不同分为青春期、妊娠期、泌乳期及退化期,采用激光共聚焦显微镜检测胰岛素样生长因子在奶山羊乳腺各生长阶段的表达及定位,通过定量分析来比较胰岛素样生长因子在奶山羊乳腺各生长阶段表达的差异,描述其在奶山羊乳腺发育过程中的作用.结果显示:胰岛素样生长因子及胰岛素样生长因子受体在奶山羊乳腺法如各时期均有表达,表达水平与乳腺发育密切相关.     

蛹虫草子实体多糖对腹水型肝癌移植瘤超微结构的影响

目的:研究蛹虫草多糖(CMPS)对小鼠移植型腹水型肝癌(H22)体内诱导肿瘤细胞凋亡作用,探讨其抑瘤作用机制。方法:建立H22移植瘤小鼠模型,采用电镜技术观察H22荷瘤小鼠肿瘤组织的超微结构改变;免疫组织化学法检测蛹虫草多糖作用后H22肿瘤组织细胞内P53蛋白的表达情况。结果:电镜观察到蛹虫草多糖作用后H22肿瘤组织细胞有早期凋亡改变,肿瘤组织内有凋亡细胞存在;免疫组化实验结果显示,蛹虫草多糖作用后H22小鼠肿瘤组织细胞突变型P53蛋白的表达水平降低。结论:蛹虫草多糖具有诱导小鼠H22肝癌细胞凋亡作用,促凋亡作用可能与其降低H22小鼠肿瘤组织细胞内突变型P53蛋白的表达有关。      

Starch particles modified with gelatin as novel small carriers for mammalian cells

Promotion of cell aggregation by addition of small starch particles with and without modification with gelatin was investigated, and the influence of CHO cell aggregation by the addition of modified starch on substrate consumption and production of tissue plasminogen activator (tPA) was investigated. Addition of starch particles (approximately 10 micromPhi) covalently bonded with gelatin was very effective in forming cell aggregates ranging from 100 to 300 microm in diameter and decreased the cell sedimentation time to one-thirtieth that of the normal time. There was almost no influence of the addition of modified starch particles on cell metabolism and tPA production. Cell aggregation makes it easy to separate cells from culture during changing of medium in a cell suspension culture without the use of special equipment, such as centrifuges, hollow fiber membranes, and spin filters.     

改性果胶结构、功能及方法的研究进展

果胶是存在于高等植物初生细胞壁和中胞层中的一种酸性多糖,因天然、无毒且价廉而被广泛地应用于食品与医药工业。但是,果胶由于分子量较大且不同来源果胶结构上的巨大差异而限制了其在食品及医药行业的广泛应用。因此,该文就改性果胶的结构、功能特性以及改性方法进行了详细综述,旨在为改性果胶在食品及医药行业的应用提供理论指导。     

Development of chitosan-magnetite aggregates containing Nitrosomonas europaea cells for nitrification enhancement

A cell suspension of the nitrifying bacterium Nitrosomonas europaea obtained after 96-h cultivation was subjected to magnetic separation using chitosan-conjugated magnetite particles (chitosan-magnetite), which have the ability to form aggregates with microbial cells. An equilibrium condition was obtained at room temperature after 30 min and over 90% of the cells were recovered when the chitosan-magnetite concentration was 200 mg/l. The relationship between the cell concentration in the supernatant in equilibrium and the number of cells adsorbed per 1g chitosan-magnetite was expressed by a Freundlich-type adsorption equation. A high nitrifying bacterium activity yield was obtained with a chitosan-magnetite concentration between 100 and 200 mg/l. Repeated batch culture resulted in more N. europaea cells accumulating on the aggregates and as a consequence their nitrification activity improved further. The chitosan-magnetite/cell aggregates were recovered and employed to remove ammonia from artificial wastewater together with PVA-alginate gel beads containing the denitrifying bacterium Paracoccus denitrificans. A higher ammonia removal rate was achieved under aerobic conditions in comparison with that obtained when N. europaea and P. denitrificans were coimmobilized in PVA-alginate gel beads.     

Formulation of sunscreens with enhancement sun protection factor response based on solid lipid nanoparticles

Solid lipid nanoparticle (SLN) was regarded as new topical delivery systems for pharmaceutical and cosmetic active ingredients. The purpose of this study is to develop carrier systems for organic and inorganic sunscreens based on a matrix composed of carnauba wax and decyl oleate. Formulae (F1–F7) were prepared using butyl methoxydibenzoylmethane and octyl methoxycinnamate as organic components, and titanium dioxide (TiO₂) was used as inorganic component. Both types of sunscreens were incorporated into SLN formulations using classical method of preparation. To evaluate the effect of the pigments on the nanoparticles, particle size was measured using Mastersizer particle size analyser. UV‐protection abilities of formulations were investigated by the in vitro sun protection factor test (SPF). Further parameters determined were spreadability as well as viscosity. The rheological behaviour of the formulations was also carried out. From the plot of log of shear stress vs. log of shear rate, the slope of the plot representing flow index and ontology of the y‐intercept indicating consistency index was calculated. The formulae showed a flow index of 0.2074–0.4005 indicating pseudoplastic flow behaviour. Significant increases in SPF values up to about 50 were reported after the encapsulation by using organic and inorganic filters in Canada wax and decyl oleate. So, SLN could be appropriate vehicles to carry organic and inorganic sunscreens. The rational combination of cinnamates, titanium dioxide and Zinc oxide has shown a synergistic effect to improve the SPF of cosmetic preparations.     

Substratum modulation of epidermal growth factor receptor expression by normal mouse mammary cells

Normal mouse mammary cells synthesize the basement membrane scaffold on which the cells rest in vivo. This extracellular matrix material serves important functions in the growth and differentiation of the mammary epithelium. Components of the basement membrane negatively regulate basement membrane collagen biosynthesis in response to epidermal growth factor stimulation. This effect is shown to correlate with changes in growth factor receptor regeneration following ligand-induced receptor down-regulation. The results suggest that while control of basement membrane synthesis may be manifest in part by the availability of growth factors, the environment in which the mammary cell finds itself is also very important.     

Response of human epithelial cells to culture surfaces with varied roughnesses prepared by immobilizing dendrimers with/without D-glucose display

To investigate the response of human epithelial cells to substrates with nanoscale modifications, dendrimer-immobilized surfaces were prepared with or without D-glucose displayed as a terminal ligand, giving topographic structures with mean roughnesses (R(a)) of 1.8-11.0 nm. With an increase in the R(a) value up to 4.0 nm, the epithelial cells cultured on naked dendrimer surface without D-glucose display were somewhat stretched in their morphology compared with those on a nonmodified plain surface. However, for the R(a) values higher than 4.0 nm, such cell stretching was inhibited, resulting in the predominant existence of round-shaped cells. The change in cell morphology was appreciable on the surfaces with D-glucose-displayed dendrimers. When the R(a) value increased up to 4.5 nm on these surfaces, in particular, the enhancement of cell stretching was recognized, and fluorescence microscopic observation supported the hypothesis that the glucose-transporter-mediated adhesion of cells to the surface encouraged the development of filopodia and stress fibers, thereby improving focal contact with the surface. Our results suggest that the combination of displaying D-glucose and modulating roughness can promote cytoskeletal formation accompanied by marked cell elongation on culture surfaces.     

Synergistic effect of D-glucose and epidermal growth factor display on dynamic behaviors of human epithelial cells

We investigated the synergistic effect of D-glucose and epidermal growth factor (EGF) display on the dynamic cellular behaviors of morphology and migration in a culture of human epithelial cells. The time-lapse observation revealed that the cells on the D-glucose/EGF-displayed substrate were endowed with enhanced migration, accompanied with periodic changes in morphology between round and stretched shapes. Immunofluorescence staining of phosphotyrosine PY20 and vinculin was conducted to determine the intracellular localization of phosphorylated tyrosine expression and focal contact formation, respectively. On the substrate displaying D-glucose and EGF, the cells exhibited increases in the levels of the expression of phosphorylated tyrosine and the formation of focal contacts not only at the cellular periphery but also in the cell body. These findings supported the consideration that the displayed D-glucose causes the cells to be in close contact with the surface via grasping glucose transporters on the cytoplasmic membrane.     

Derivation, growth and applications of human embryonic stem cells

Human embryonic stem (hES) cells are pluripotent cells derived from the inner cell mass cells of blastocysts with the potential to maintain an undifferentiated state indefinitely. Fully characterised hES cell lines express typical stem cell markers, possess high levels of telomerase activity, show normal karyotype and have the potential to differentiate into numerous cell types under in vitro and in vivo conditions. Therefore, hES cells are potentially valuable for the development of cell transplantation therapies for the treatment of various human diseases. However, there are a number of factors which may limit the medical application of hES cells: (a) continuous culture of hES cells in an undifferentiated state requires the presence of feeder layers and animal-based ingredients which incurs a risk of cross-transfer of pathogens; (b) hES cells demonstrate high genomic instability and non-predictable differentiation after long-term growth; and (c) differentiated hES cells express molecules which could cause immune rejection. In this review we summarise recent progress in the derivation and growth of undifferentiated hES cells and their differentiated progeny, and the problems associated with these techniques. We also examine the potential use of the therapeutic cloning technique to derive isogenic hES cells.     

Microbial growth,communities and sensory characteristics of vacuum and modified atmosphere packaged lamb shoulders

Packaging fresh lamb in a vacuum (VAC) versus a 100% CO₂ modified atmosphere (MAP) may influence product shelf-life and the bacterial communities. While VAC is a common packing method and 100% CO₂ MAP is used in some countries, there is little information about how these different techniques affect the growth of spoilage bacteria and sensory attributes of lamb. The aim of this study was to assess changes in microbiological and organoleptic properties, and determine differences in microbial communities by terminal restriction fragment length polymorphism (TRFLP) and 454 pyrosequencing, in bone-in (BI) and bone-out (BO) MAP- and VAC-packed lamb shoulders stored at −0.3 °C over 12 wk. VAC and MAP lamb shoulders were acceptable in sensory test scores over 12 wk of storage at −0.3 °C, despite total viable count (TVC) and lactic acid bacteria (LAB) levels increasing to 8 log₁₀ CFU/cm² for VAC lamb and 4–6 log₁₀ CFU/cm² for MAP lamb. Similar to the sensory results, there were no significant differences in microbial communities between BI and BO product. However, types of bacteria were different between VAC and MAP packaging. Specifically, while VAC shoulder became dominated by Carnobacterium spp. in the middle of the storage period, the MAP shoulder microbial population remained similar from the start until later storage times.     

Development and validation of a short-term, serum-free culture system for bovine granulosa cells: evaluation of the effects of somatotropin and growth hormone-releasing factor on estradiol production

The objective of this study was to develop and validate a short-term, serum-free culture system to determine whether recombinant bovine somatotropin (rbST) or recombinant bovine growth hormone-releasing factor (rbGRF) altered the estradiol-producing capacity of bovine granulosa cells isolated from dominant or subordinate follicles of the first follicular wave. Thus, ovaries were obtained at an abattoir from cows that were between d 2 to 5 or 6 to 10 of the estrous cycle. Three size classes of follicles were isolated from each cow's ovaries: small (2 to 5 mm in diameter), medium (6 to 14 mm), or the largest (6 to 19 mm). In vivo steroid-producing capacity of follicles was assessed by measuring concentration of estradiol, progesterone, androstenedione and 5alpha-dihydrotestosterone in each follicle. In vitro steroid-producing capacity was assessed by culturing granulosa cells from the different follicle sizes for 48 h in serum-free media with 19-OH androstenedione and measuring the estradiol and progesterone concentrations in media at the end of culture. The effect of different doses of FSH, rbST, or rbGRF on estradiol and progesterone production by granulosa cells from each follicle size class during d 2 to 5 or 6 to 10 was also evaluated. A high percentage (91.7%) of the largest follicles obtained on d 2 to 5 was estrogen-active (estradiol > progesterone) compared with other follicle classifications (d 2 to 5, small = 0%, medium = 13.8%; d 6 to 10, small = 0%, medium = 3.3%, largest = 33.3%). Estradiol was highest (P < 0.05) in the largest follicle on d 2 to 5 and correlated positively with follicle diameter. The pattern of in vitro production of estradiol by granulosa cells from the different follicle size classes reflected the original in vivo capacity of follicles to produce estradiol. However, only granulosa cells from the largest estrogen-active follicle on d 2 to 5 produced more estradiol than progesterone in vitro. Progesterone production by granulosa cells from all follicle classifications was increased by FSH, but FSH only enhanced estradiol production by granulosa cells from the largest estrogen-active follicles on d 2 to 5. Recombinant bST blocked the FSH-induced increase in estradiol by granulosa cells from the largest estrogen-active follicles on d 2 to 5, whereas rbGRF had no effect on steroid production. Based on these results, we concluded that short-term, serum-free culture of bovine granulosal cells obtained from first-wave follicles at an abattoir could be used to reflect reliably the original in vivo estradiol-producing capacity of granulosal cells, and that neither rbST nor rbGRF enhance basal or FSH-induced estradiol production by bovine granulosa cells from first-wave follicles.     

Solamargine upregulation of Fas, downregulation of HER2, and enhancement of cytotoxicity using epirubicin in NSCLC cells

Nonsmall-cell lung cancer (NSCLC) is not generally a chemosensitive tumor, and the mechanism of resistance to the relevant anticancer drugs has not been fully elucidated. Solamargine (SM), the major steroidal glycoalkaloids extracted from the Chinese herb Solanum, inhibits the growth of human tumor cells. We have previously demonstrated that SM regulates tumor necrosis factor receptors (TNFRs)- and mitochondria-mediated pathways and sensitizes NSCLC cells to initiate apoptosis. Interestingly, this investigation reveals that SM up-regulated Fas expression and down-regulated the expression of HER2, whose overexpression is associated with resistance to drugs, and promotes chemotherapy-induced apoptosis in NSCLC A549 and H441 cells. After treatment with SM, the expression of HER2 mRNA was correlated with the expression of topoisomerase IIalpha (TOP2A) mRNA. The combinatory use of low concentrations of SM with low-toxic topoisomerase II inhibitor epirubicin accelerated apoptotic cell death. Therefore, the downregulation of the HER2 and TOP2A expression by SM with epirubicin may partially explain the SM and epirubicin cytotoxicity synergy effect in NSCLC. Results of this study suggest that SM induces Fas and TNFR-induced NSCLC cell apoptosis and reduces HER2 expression. These findings provide the synergistic therapeutic interaction between SM and epirubicin, suggesting that such combinations may be effectively exploited in future human cancer clinical trials.     

Inducing chondrogenic differentiation in injectable hydrogels embedded with rabbit chondrocytes and growth factor for neocartilage formation

A thermoreversible hydrogel of poly(NiPAAm-co-AAc) was used as an injectable cell and growth factor delivery carrier for cartilage tissue engineering. Rabbit chondrocytes were embedded in composite hydrogels coencapsulated with transforming growth factor beta3 (TGFbeta3). Hydrogel constructs consisting of embedded cells encapsulated by the thermoreversible hydrogel served as controls to assess the effects of TGFbeta3 on chondrogenic differentiation. The hydrogel constructs were injected subcutaneously into nude mice and then monitored for up to 8 weeks after injection. After 8 weeks of implantation, the engineered cartilage acquired normal histological and biochemical properties. These results highlight the potential of growth factor in a hydrogel embedded with chondrocytes as a candidate material for neocartilage formation.