Induction of an antimicrobial biotin-binding egg white protein (avidin) in chick tissues in septicEscherichia coli infection

Summary The induction of avidin in chick tissues was found in septicEscherichia coli infection. Avidin concentrations in the plasma roughly corresponded to those in the other tissues studied which suggests that avidin in chicks is a secretory protein.Acknowledgments. We thank Mrs O. Kurronen, Miss T.-M. Mattila and Mr C. Hartmann for technical assistance and Dr M.S. Kulomaa for the performance of radioimmunoassay. We are very much obliged to Dr T. Metsä-Ketelä for valuable criticism. The work was supported by grants from the Ford Foundation (No 760-0526) and the Scientific Foundation of the Tampere City.     

Biotin-binding proteins in eggs of oviparous vertebrates

Summary Biotin-binding was found in the egg whites and yolks of all 23 avian species studied, and in a turtle, but the amount varied considerably even in related species. There was no clear correlation in biotin-binding between egg white and yolk in various species. Antigenic determinants of avidin in different species have changed in the course of evolution as compared with those of chicken egg white avidin.We thank Mr Jukka Peltonen and Mr Antti Karlin for the collection of the avian eggs with permission obtained from the Ministry of Agriculture, and Mr Reino Saarinen for the turtle eggs. The authors are indebted to Mrs Outi Kurronen Miss Riitta Mero and Miss Tiina-Maija Mattila for technical assistance. This work was supported by the Ford Foundation Grants No. 760-0526 and No. 790-0665.     

Regulation of glucose transport in Aspergillus nidulans.

Pyruvate and acetate inhibited the uptake of glucose by Aspergillus nidulans; although there were significant variations in glucose uptake rate, the intracellular concentration of acetate was almost identical in biotin-supplemented, normal and deficient cells. The in vitro activity of glucose-binding protein was not affected by biotin, avidin, acetate or acetyl-CoA.     

Regulation of glucose transport in Aspergillus nidulans

Summary Pyruvate and acetate inhibited the uptake of glucose by Aspergillus nidulans; although there were significant variations in glucose uptake rate, the intracellular concentration of acetate was almost identical in biotin-supplemented, normal and deficient cells. The in vitro activity of glucose-binding protein was not affected by biotin, avidin, acetate or acetyl-CoA.J. D. Desai gratefullt acknowledges the receipt of Research Fellowship from the Govt. of India, Department of Atomic Energy, Bombay.     

Genetically engineered avidins and streptavidins

Chicken avidin and bacterial streptavidin, (strept)avidin, are proteins widely utilized in a number of applications in life science, ranging from purification and labeling techniques to diagnostics, and from targeted drug delivery to nanotechnology. (Strept)avidin-biotin technology relies on the extremely tight and specific affinity between (strept)avidin and biotin (dissociation constant, K_d≈10⁻¹⁴–10⁻¹⁶ M). (Strept)avidins are also exceptionally stable proteins. To study their ligand binding and stability characteristics, the two proteins have been extensively modified both chemically and genetically. There are excellent accounts of this technology and chemically modified (strept)avidins, but no comprehensive reviews exist concerning genetically engineered (strept)avidins. To fill this gap, we here go through the genetically engineered (strept)avidins, summarizing how these constructs were designed and how they have improved our understanding of the structural and functional characteristics of these proteins, and the benefits they have provided for (strept)avidin-biotin technology. Received 22 June 2006; received after revision 1 August 2006; accepted 21 September 2006     

Modulation of signal transduction through the cellular prion protein is linked to its incorporation in lipid rafts

Because expressed at a significant level at the membrane of human T cells, we made the hypothesis that the cellular prion protein (PrP^c) could behave as a receptor, and be responsible for signal transduction. PrP^c engagement by specific antibodies was observed to induce an increase in cytosolic calcium concentration and led to enhanced activity of Src protein tyrosine kinases. Antibodies to CD4 and CD59 did not influence calcium fluxes or signaling. The effect was maximal after the formation of a network involving avidin and biotinylated antibody to PrP^c and was inhibited after raft disruption. PrP^c localization was not restricted to rafts in resting cells but engagement was a prerequisite for signaling induction, with concomitant PrP^c recruitment into rafts. These results suggest a role for PrP^c in signaling pathways, and show that lateral redistribution of the protein into rafts is important for subsequent signal transduction.Received 22 July 2004; received after revision 10 September 2004; accepted 7 October 2004     

Participation of microtubules and microfilaments in the transcellular biliary secretion of immunoglobulin A in primary cultures of rat hepatocytes

Summary The biliary secretion of immunoglobulin A (IgA) in primary hepatocyte cultures was investigated by means of immunofluorescence. The characteristic accumulation of IgA in visible bile canaliculi was found to be strongly inhibited by vinblastine and colchicine or by cytochalasin B, but its surface binding was not.The author thanks Prof. Dr D. Mecke for his support and encouragement. The excellent technical assistance of Mrs M. Behringer and Mrs A. Schneck is gratefully acknowledged. The author is grateful to the BIOTEST Serum Institut (Frankfurt) for the kind gift of human IgA. This work was supported by the Deutsche Forschungsgemeinschaft.     

Cholera toxin B-subunit incorporation into synaptic vesicles of the neuromuscular junction of the rat

Summary The B-subunit of cholera toxin, a nontoxic macromolecule which binds specifically to GM1 ganglioside, was conjugated to colloidal gold and injected into skeletal muscle of the rat. It was taken up rapidly in vesicles in the terminal axons at the neuromuscular junctions. Injection of albumin-colloidal gold conjugates resulted in an insignificant uptake. The results indicate that uptake of extracellular macromolecules into the terminal axon of the neuromuscular junction may be greatly enhanced by binding to gangliosides at the presynaptic membrane, and that it may occur without association with vesicular recycling related to transmitter release.The study was supported by grants from the Swedish Medical Research Council (proj. No. 07122).—Part of this study was performed at INSERM U-153, Paris, headed by Dr M. Fardeau.     

携SiRNA的聚乳酸羟基乙酸微球对Bel-7402/5-Fu细胞MDR1基因沉默作用的研究

目的 探讨携SiRNA的聚乳酸羟基乙酸(PLGA)微球通过沉默肝癌耐药细胞多药耐药基因(MDR1)基因,实现肝癌耐药的逆转.方法 合成针对MDR1的RNA干扰小片段(SiRNA),通过超声复乳法制备携药微球,转染肝癌耐药细胞Bel-7402/5 -Fu.运用Real-time PCR与Western blot方法,通过检测其mRNA及P糖蛋白表达水平,评价RNA干扰对MDR1表达的影响.MTT法检测RNA干扰逆转Bel-7402/5 Fu细胞对药性的效果,通过实验组细胞和对照组细胞之间的半数抑制剂量(IC50),计算RNA干扰组细胞的耐药逆转倍数.结果 在肝癌耐药细胞Bel-7402/5-Fu中,RNA干扰明显抑制了MDR1 mRNA和蛋白产物P糖蛋白的表达水平,且出现了P糖蛋白的持续低表达.MTT法显示,相同药物浓度下,实验组细胞生长明显受到抑制,表明其耐药性明显下降,其对药逆转倍数为11.56.结论 携SiRNA的PLGA微球能够有效减少肝癌耐药细胞Bel-7402/5-Fu的MDR1mRNA及P糖蛋白的表达水平,降低其耐药性.     

Existence of several non-specific recognition systems in macrophages]

Rat peritoneal cells were made to bind five particle species: immunoglobulin-coated Sheep red cells, glutaraldehyde-treated Sheep red cells, latex beads, leishmania and tumor cells. The dependence of binding on various physico-chemical parameters was studied. The binding of latex beads or Leishmania was not inhibited by cold (4 degrees C), sodium azide, cytochalasin B and ethyleneglycol or dimethylsulphoxide. The binding of immunoglobulin-coated Sheep red cells was unaffected by cold and azide, but it was inhibited by cytochalasin B, ethyleneglycol and dimethylsulphoxide. The binding of glutaraldehyde-treated Sheep red cells was inhibited by cold, azide and ethyleneglycol, but it resisted cytochalasin B and dimethylsulphoxide. The binding of tumor cells was inhibited by azide, cytochalasin B, ethyleneglycol and dimethylsulphoxide. It is concluded that: (a) macrophages are endowed several sets of non-specific binding structures that are differently affected by physico-chemical parameters, which provides a simple way of characterizing them; (b) the expression of a given binding structure on the macrophage membrane is modulated by metabolic inhibitors; (c) some lymphocytes were able to bind tumor cells or Leishmania. Thus, lymphocytes and macrophages might share some non-specific adhesive structures.     

Effects of alpha- and beta-adrenergic blockers on the actions of noradrenaline on body temperature in the newborn guinea-pig

Summary The effect of NA injected into the lateral cerebral ventricle on T_c was blocked by alpha-adrenergic receptor blockers, but not by beta-receptor blockers, whereas the effect of systemically administered NA was blocked by i.p. administered beta-receptor blockers, but not by alpha-blockers.Acknowledgments. The author is indebted to Ciba-Geigy Ltd for generous gift of phentolamine, and to Imperial Chemical Industries Ltd, for supplying propranolol and practolol.     

Some characteristics of urokinase released in organ culture of human kidney

Summary Plasminogen activator produced in organ culture of human kidney, i.e. in the histotypical arrangement of the tissue, was partially purified by affinity chromatography on para-aminobenzamidine coupled to Sepharose by a 6-carbon spacer, followed by gel chromatography on Sephadex G-100. The molecular weight of 2 active peaks were 27,000 and 52,000 daltons respectively. It was inhibited by DFP and by IgG antiurokinase.This study was supported by grant from the Swedish Medical Research Council (B77-17X-04523-03B).     

超临界CO2萃取法提取库尔勒香梨精油及其成分分析研究

采用超临界CO2萃取法提取库尔勒香梨精油,用气相色谱-串联质谱技术对其成分进行分析,并对几种提取方法进行综合比较。结果表明,与水蒸气蒸馏法、固相微萃取法相比,超临界CO2萃取法具有香梨精油提取率最高,为0．0549％。感官分析的结果表明,超临界CO2萃取法所得的库尔勒香梨精油颜色为橙色透明液体,而且风味好。气相色谱-质谱联用（GC-MS）分析结果表明：超临界CO2萃取法所得的香梨精油中共鉴定出28种成分。丁酸乙酯、顺-7-十四烯-1-醇和乙酸己酯的含量最高,含量分别为5．19％、4．85％和4．37％。     

Some characteristics of urokinase released in organ culture of human kidney.

Plasminogen activator produced in organ culture of human kidney, i.e. in the histotypical arrangement of the tissue, was partially purified by affinity chromatography on para-aminobenzamidine coupled to Sepharose by a 6-carbon spacer, followed by gel chromatography on Sephadex G-100. The molecular weight of 2 active peaks were 27,000 and 52,000 daltons respectively. It was inhibited by DFP and by IgG antiurokinase.     

Endolymphatic leakage in case of acute loss of cochlear microphonics

Summary Rapid loss of cochlear microphonics in guinea-pigs previously exposed to high-energy impulse noise was shown to be related to the breakdown of the endolymphatic boundary. The cochlear duct was rendered leaky by deterioration of the reticular membrane, and damage of sensory and supporting cells.Aided by grants from the Ministerium für Gesundheitswesen der DDR.     

Colon absorption of water and NaCl in the rat during lactation and the possible involvement of prolactin

Summary The absorption of water and NaCl by the ascending colon of female rats was significantly increased by prolactin treatment in virgin rats and during suckled lactation. Bromocriptine treatment of lactating rats resulted in decreased colonic absorption, suggesting that increased prolactin secretion may be responsible for the enhanced colonic absorption seen during lactation.This study was aided by NIH/Fogarty Fellowship F 05 TWO 2738 and by NSF Grant PCM-78-10348 to Professor H.A. Bern.The author is greatly indebted to Professor H. A. Bern for his support and helpful suggestions. Ovine prolactin was generously provided by NIAMDD. Professor E. Flückiger, Sandoz Ltd., kindly provided the bromocriptine used in this study. The assistance of William J. Young in taking care of the animals is greatly appreciated.     

Potentiation by taurine of the inotropic effect of ouabain and the content of intracellular Ca++ and taurine in the heart.

Under certain conditions, taurine (3.0mM) potentiated cardiac contractile response to ouabain in the normal medium. The potentiation by taurine was also observed in the low K+ medium, in which the positive inotropic effect of ouabain increased. The potentiation as seen in both media was, at least in part, due to the increase by taurine of Ca++ content in the heart. Taurine in the heart was not directly related to this potentiation.     

Effect of oridonin, a Rabdosia diterpenoid, on radiosensitization with misonidazole

The radiosensitization brought about by oridonin, one of the Rabdosia diterpenoids, alone or in combination with misonidazole, was investigated in Chinese hamster V79 cells. The enhancement ratio of 1.92 was obtained when 0.01 mM oridonin and 1 mM misonidazole were administered to hypoxic cells under radiation. The enhancement ratios of oridonin and misonidazole for hypoxic cells were 1.16 and 1.59 respectively. Hence, a supra-additive effect was obtained by the combined treatment with these two drugs. Under aerobic conditions, no effect of 0.01 mM oridonin on the radiosensitization caused by misonidazole was observed.     

The effect of bradykinin on the electrical activity of rat jejunum

Summary Bradykinin increased the potential difference across both the jejunum and colon of the rat. This effect was significantly reduced by indomethacin, suggesting that it was mediated by prostaglandins. The possibility that bradykinin may contribute to the diarrhoea of the carcinoid syndrome by inducing a net secretory state in the intestine is discussed.