环境噪声对中学生心脑血管功能影响初探

为观察环境噪声对中学生心脑血管功能的影响，对初三年级学生脑血流图和心电图进行了检查。结果发现Ｇ：波形的改变为上升时间延长，上升支倾斜，三波关系异常，重搏波减弱等现象。接触噪声５０－５５ｄＢ（Ａ）组，未见明显改变（Ｐ〉０．０５），５５￣６０ｄＢ（Ａ）组和〉６０ｄＢ（Ａ）组脑动脉张力轻微增高，显著高于对照组（Ｐ〈０．０５）。异常心电图以窦性心律失常为多见。异常心电图出现频率，除５０￣５５ｄＢ（Ａ）组外     

Retinoic acid binding properties of the lipocalin member beta-lactoglobulin studied by circular dichroism,electronic absorption spectroscopy and molecular modeling methods

Interaction between the Vitamin A derivative all-trans retinoic acid and the lipocalin member bovine beta-lactoglobulin (BLG) was studied by circular dichroism (CD) and electronic absorption spectroscopy at different pH values. In neutral and alkaline solutions achiral retinoic acid forms a non-covalent complex with the protein as indicated by the appearance of a negative Cotton effect around 347 nm associated to the narrowed and red shifted pi-pi(*) absorption band of the ligand. The induced optical activity is attributed to the helical distortion of the conjugated chain caused by the chiral protein binding environment. As the disappearing CD activity showed in the course of CD-pH titration experiment, retinoic acid molecules dissociate from BLG upon acidification but this release is completely reversible as proved by the reconstitution of the CD and absorption spectra after setting the pH back to neutral. This unique behavior of the complex is explained by the conformational change of BLG (Tanford transition) which involves a movement of the EF loop at the entrance of the central cavity from open to closed conformation in the course of pH lowering. From these results it was inferred that retinoic acid binds within the hydrophobic calyx of the beta-barrel.     

Cow’s milk protein β-lactoglobulin confers resilience against allergy by targeting complexed iron into immune cells

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人胰岛素原乳腺表达基因构建及其在转基因小鼠乳汁中的表达

从绵羊和人的基因组中用PCR扩增分别克隆了羊乳球蛋白 (BLG) 5’和 3’调控区及人胰岛素原 (hINS)基因组DNA ,并以此为基础构建了人胰岛素原乳腺表达载体 ( pSh -BLG -hINS)。该表达载体包括 4.2kbBLG 5’调控区和 2 .1kbBLG 3’调控区 ,以及 1 .2kb人胰岛素原基因组DNA。将绿色荧光蛋白基因与BLG 5’和 3’调控区融合后转化乳腺细胞系 (TD47) ,通过荧光显微镜观察和紫外吸收检测 ,证明GFP在TD47乳腺细胞系中获得了表达。用BLG -hINS基因分别注射小鼠 ,通过PCR和限制性内切酶检测分析 ,共获得 5只转基因小鼠。经放免 (RIA)检测 ,两只转基因母鼠乳汁中人胰岛素原的表达量分别为 37.44和 39.99mg/L。该结果表明 ,本文所构建的 pBLG乳腺表达结构 ,能够调控外源基因在乳腺表达     

Materno–fetal passage of nutritive and inhalant allergens across placentas of term and pre-term deliveries perfused in vitro

BACKGROUND: The pre- and postnatal environment appears to be of crucial importance for the manifestation of allergic diseases, which often begin during infancy. Although T cell reactivity of fetal origin to a range of common allergens is present in most cord blood samples, the immunological basis remains unclear. OBJECTIVE: In order to test the hypothesis of transplacental allergen transfer we studied double-sided open ex vivo perfusion experiments of isolated placental cotyledons with the nutritive allergens beta-lactoglobulin (BLG) and ovalbumin (OVA) and the inhalant major birch pollen allergen Bet v1. METHODS: Placentas of full-term and pre-term newborns were obtained immediately after delivery to recover functionally active maternal and fetal circulations. Thus, a fetal artery and a fetal vein were cannulated and perfused with pure medium (fetoplacental circulation), whereas the intervillous space of placentas was flushed with allergen containing medium by puncture of the basal plate (maternoplacental circulation). Samples that were collected throughout the perfusion experiment from fetal venous outflow were tested by allergen-specific enzyme-linked immunosorbent assays (ELISA) for the presence of allergens indicative of materno-fetal transplacental passage. RESULTS: We observed transplacental transfer of BLG, OVA and Bet v1 in placentas of term as well as premature deliveries. The respective allergen was readily detectable in fetal effluent at the beginning of the perfusion experiment and allergen levels reached a plateau after about 2 h. The steady state transfer rate of BLG and OVA in term placentas was 0.012% +/- 0.001 and 0.013% +/- 0.001 of total dose, i.e. 130.21 +/- 7.41 ng/mL and 115.83 +/- 6.07 ng/mL, respectively. The observed transfer rate of Bet v1 after 2h of perfusion was 0.155% +/- 0.034 of total dose, that is 2.41 +/- 1.36 ng/mL. Transplacentally transferred concentration of BLG and OVA in pre-term placentas increased continuously throughout perfusion time from 5.32 +/- 0.92 ng/mL at 1 min to 87.53 +/- 21.93 ng/mL at 120 min and 1.35 +/- 0.31 ng/mL at 1 min to 112.87 +/- 5.25 ng/mL at 150 min, respectively. CONCLUSION: Allergen-specific cord blood reactivity may be attributed to low levels of allergens crossing the human placenta and providing the fetus with the necessary stimulus for T cell priming.     

Allergenic changes in β-lactoglobulin induced by microwave irradiation under different pH conditions

The allergenicity of β-lactoglobulin (BLG) was assayed by Ussing chamber after microwave irradiation of whey proteins at different pH values, in a murine model of BLG allergy. BALB/c mice were sensitised intraperitoneally with BLG. Serum levels of BLG-specific IgG, IgG1, IgG2a and IgE were analysed by Enzyme-Linked Immunosorbent Assay (ELISA). Local anaphylactic responses and residual allergenicity of various treated whey proteins were performed in vitro in Ussing chamber. BLG immunisation was associated with strong IgG, IgG1, IgG2a and IgE production, a significant increase in short current circuit (Isc) and high conductance (G) response. The allergenic potential of BLG was markedly reduced after microwave irradiation at 300 or 700 W of whey proteins at pH values 6.8 or 4.6 (Isc and G remained unchanged after intestine challenge with treated whey proteins). The application of microwave irradiation of whey proteins at the natural milk pH (pH 6.8) or pH 4.6 induces a significant decrease in the BLG allergenicity.     

食物过敏后肠道通透性的研究

目的：研究食人过敏原后，不同时相下的肠道黏膜通透性变化。方法：将卵蛋白（OVA）致敏大鼠分成3组，分别以OVA（2mg/mL)经肠道攻击1、6和24h后经口投用β乳球蛋白（BLG）5mg/mL,2h后采血，用ELISA法测定血清中BLG的浓度，并对小肠黏膜浸润炎性细胞计数分类。结果：3组实验大鼠血清BLG浓度与对照组比较均增高，P值有显著差异（P＜0．01）；实验组间血清BLG的质量浓度比较无显著差异（P＞0．05），且实验组大鼠小肠黏膜内浸润的炎性细胞种类因食入后时相不同而有差异。结论：在食物过敏反应中，不论速发型或迟发型变态反应，肠道的通透性均增加，但引起的机制不同。     

Maternally delivered nutritive allergens in cord blood and in placental tissue of term and preterm neonates

BACKGROUND: The proliferation of cord blood mononuclear cells in response to nutritive and inhalant allergens implies intrauterine exposure with resulting T cell priming. However, the mechanisms triggering these fetal allergen-specific immune responses are incompletely understood. METHODS: We studied the placental release of endogenous beta-lactoglobulin (BLG) and ovalbumin (OVA) by the use of an open ex vivo placental perfusion model. Preterm and term placentas were obtained immediately after delivery to recover functionally active fetal and maternal circulations. Fetal and maternal perfusate samples were collected throughout the perfusion experiments with medium. Matched cord blood samples were collected separately. All samples were tested for the presence of OVA and BLG by allergen-specific ELISAs. RESULTS: In 16 out of 19 placentas, the nutritive allergens could be detected both in fetal and maternal perfusate samples. Fetal wash out levels of the allergens BLG and OVA from the placental tissue of preterm and term deliveries were observed in traces and up to 44.4 and 2.6 ng/mL, respectively. In cord blood of preterm and term neonates, BLG and OVA could be detected at concentrations up to 16.7 and 5 ng/mL, respectively. CONCLUSION: These findings provide direct evidence for the release of tiny amounts of nutritive allergens from placental tissue indicating diaplacental allergen transfer and fetal exposure to nutritive allergens in vivo.     

Preparation of sub-100-nm β-lactoglobulin (BLG) nanoparticles

Sub-100-nm nanoparticles were prepared from β-lactoglobulin (BLG) with a narrow size distribution by a desolvation method using glutaraldehyde for cross-linking. With pre-heating of the BLG solution to 60°C and subsequent pH readjustment to 9.0, nanoparticles of 59?±?5?nm were obtained with improved uniformity. Bovine serum albumin (BSA) nanoparticles, prepared under similar conditions for comparison, were larger and less uniform. The half-width of 80% particle distribution was used to compare the uniformity of particle size distribution. The stability of the nanoparticles was investigated by degradation tests at neutral and acidic pHs with and without proteolytic enzymes, trypsin and pepsin. The degradation time, determined by a graphical approach, was used to compare the relative stabilities of BLG and BSA nanoparticles. The particles of BLG were more stable than those of BSA in acidic and neutral media with and without added enzymes.