Roles of secreted frizzled-related proteins in cancer

The Wnt signaling pathway is implicated in a variety of biological processes ranging from developmental cell fate to human disease. The components involved in Wnt signaling have been under intense investigation over the last 2 decades. Aberrant canonical Wnt activation has been linked to tumor formation and involves activation of effector molecules or loss of tumor suppressor function. Secreted frizzled-related proteins （sFRPs） are Wnt antagonists. In recent years, accumulating evidence has suggested that sFRPs act as tumor suppressors because their expression is frequently silenced in cancer by promoter hypermethylation. However, sFRPs may also promote cell growth in some contexts. Here, we focus on the known knowledge of sFRPs in tumorigenesis.     

DSIP-induced changes of the daily concentrations of brain neurotransmitters and plasma proteins in rats

The influence of delta sleep-inducing peptide (DSIP) on the brain neurotransmitters 5-HT, dopamine and norepinephrine and plasma proteins/corticosterone concentrations for four time points within the 24 hr following IV injection of 30 nmol/kg was investigated in rats. DSIP administered in the morning or in the evening respectively induced changes in nearly all measured parameters. Different effects were observed for different times of administration. The most marked changes were found in the level of serotonin during daytime. In view of the multivariate results obtained by measuring several parameters at multiple time points, a method was developed to describe the time-dependent changes. By means of "circadian rhythm statistics" based on a statistical likelihood analysis we found that multiple and different changes within the factor's daily variation are induced by one injection of DSIP. A multidimensional scaling of the results provides further insights into the correlations of the DSIP-induced effects on plasma and brain factors which are therefore tentatively termed "programming functions." These apparently involve not just sleep induction but also act on multiple parameters within the 24 hr rest-activity period.     

Roles of the cytoskeleton and motor proteins in endocytic sorting

After internalization, endocytic material is actively transported through the cytoplasm, predominantly by microtubule motor proteins. Microtubule-based endocytic transport facilitates sorting of endocytic contents, vesicle fusion and fission, delivery to lysosomes, cytosolic dispersal, as well as nuclear uptake and cytosolic egress of pathogens. Endosomes, like most organelles, move bidirectionally through the cytosol and regulate their cellular location by controlling the activity of motor proteins, and potentially by controlling microtubule and actin polymerization. Control of motor protein activity is manifest by increased microtubule "run lengths", and the binding of motor proteins to organelles can be regulated by motor protein receptors. A mechanistic understanding of how organelles control motor protein activity to allow for endocytic sorting presents an exciting avenue for future research.     

Reduced synthesis of hepatic and plasma proteins in rats during diethyl ether anaesthesia

The effect of diethyl ether anaesthesia on in vivo hepatic protein synthetic rates was tested in male Wistar rats. Protein synthesis was measured by an isotope technique after correction for measured levels of precursor specific radioactivity. It was shown that usual anaesthetic levels of diethyl ether reduced the rate of synthesis of liver proteins with 20% compared to a group receiving no anaesthesia. The synthesis/secretion of plasma proteins was much more inhibited, with approximately 70-80%, compared to animals either receiving no anaesthesia or pentobarbital. Monitoring of ether concentrations therefore seems necessary in experiments in which the hepatic capacity for protein synthesis/secretion is measured.     

Roles of semaphorins in neuron network formation]

A secreted semaphorin, Sema3A, is an axon guidance molecule that induces collapse of growth cones and repels axons in vitro. Neuropilin-1 (Nrp-1) is a receptor for Sema3A. To clarify the function of the semaphorin in vivo, we generated Sema3A mutant mice and Nrp-1 mutant mice by targeted disruption of the Sema3A and Nrp-1 genes, respectively. These mutant mouse embryos showed a severe defect in the trajectory and projection of PNS efferent, suggesting that the Nrp-1-mediated Sema3A signals play crucial roles in the directional guidance of nerve fibers and the establishment of PNS networks. The deprivation of Nrp-1-mediated Sema3A signals also induced disorganization of the sympathetic nervous system. In the Nrp-1 and Sema3A mutant mouse embryos, more than half of the TH-positive SG neurons were distributed at ectopic positions. As a whole, the sympathetic trunk was severely disorganized. Sema3 A recombinant proteins inhibited migration of the wild-type (Nrp-1-expressing) but not Nrp-1-deficient SG neurons in culture, suggesting that Nrp-1-mediated Sema3A inhibitory signals are essential in precise migration of SG neurons, as well as directional guidance of axons.     

Roles of focal adhesion proteins in skeleton and diseases

The skeletal system,which contains bones,joints,tendons,ligaments and other elements,plays a wide variety of roles in body shaping,support and movement,protection of internal organs,production of blood cells and regulation of calcium and phosphate metabolism.The prevalence of skeletal diseases and disorders,such as osteoporosis and bone fracture,osteoarthritis,rheumatoid arthritis,and intervertebral disc degeneration,increases with age,causing pain and loss of mobility and creating a huge social...     

Comparison of propranolol-binding plasma proteins in sheep with those in humans, dogs and rats

Alpha 1-acid glycoprotein (AGP), a plasma protein responsible for the binding of a variety of basic lipophilic drugs including propranolol, is different from other plasma proteins in being nonprecipitable after treatment with 1.2M perchloric acid (PCA). To assess the contribution of AGP to drug disposition in sheep and three other species (rats, dogs, and humans), the binding of [3H]propranolol was measured before and after PCA precipitation. PCA precipitation reduced propranolol binding 14-fold in sheep, compared to 2- to 3-fold in the other species. This implied either that sheep AGP binds less propranolol than other species, or that the AGP in sheep is more precipitable. It was not due to inherently poor propranolol binding, as whole sheep plasma bound a higher fraction than the other species. When samples of PCA-precipitated sheep plasma were analyzed using polyacrylamide gel electrophoresis, the concentration of AGP was 10-20% that of the other species. Phenobarbital induction was used as a tool to examine the changes in the plasma protein profile. Phenobarbital induced propranolol binding and AGP along with two other proteins in sheep. One of these proteins migrated similarly to AGP deglycosylated by peptide-N-glycosidase F. It is postulated that the greater precipitability of propranolol binding in sheep is due to a less glycosylated form of AGP which is not important in other species.     

Changes in drug-metabolizing enzymes of rats in ciprofibrate-induced hepatic nodules

1. Premalignant rat liver nodules produced in the resistant hepatocyte model, by exposure to carcinogenic chemicals (diethyl nitrosamine and 2-acetamidofluorene), and partial hepatectomy, exhibit decreased xenobiotic hydroxylase activities and increased conjugase activities, which are considered responsible for increased resistance to xenobiotic toxicity. 2. However, premalignant rat liver nodules generated by feeding the hypolipidaemic, peroxisomal proliferating drug, ciprofibrate, in a hypolipidaemic model, exhibit decreased hydroxylase activities but decreased conjugase activities also. 3. It is considered that reactive oxygen species (ROS) are generated in both the resistant hepatocyte model and in the hypolipidaemic model, resulting in lipid peroxidation, loss of haem, cytochromes and hydroxlase activities. 4. However, whereas there is a rebounding compensation of conjugase enzymes in the resistant hepatocyte model, this does not occur with the hypolipidaemic model, as peroxidation is probably persistent and the conjugases are continuously destroyed.     

Stereoselective binding of doxazosin enantiomers to plasma proteins from rats,dogs and humans in vitro

Aim:

(±)Doxazosin is a long-lasting inhibitor of α1-adrenoceptors that is widely used to treat benign prostatic hyperplasia and lower urinary tract symptoms. In this study we investigated the stereoselective binding of doxazosin enantiomers to the plasma proteins of rats, dogs and humans in vitro.

Methods:

Human, dog and rat plasma were prepared. Equilibrium dialysis was used to determine the plasma protein binding of each enantiomer in vitro. Chiral HPLC with fluorescence detection was used to measure the drug concentrations on each side of the dialysis membrane bag.

Results:

Both the enantiomers were highly bound to the plasma proteins of rats, dogs and humans [(−)doxazosin: 89.4%–94.3%; (+)doxazosin: 90.9%–95.4%]. (+)Doxazosin exhibited significantly higher protein binding capacities than (−)doxazosin in all the three species, and the difference in the bound concentration (C_b) between the two enantiomers was enhanced as their concentrations were increased. Although the percentage of the plasma protein binding in the dog plasma was significantly lower than that in the human plasma at 400 and 800 ng/mL, the corrected percentage of plasma protein binding was dog>human>rat.

Conclusion:

(−)Doxazosin and (+)doxazosin show stereoselective plasma protein binding with a significant species difference among rats, dogs and humans.     

Stereoselective binding of doxazosin enantiomers to plasma proteins from rats,dogs and humans in vitro

Aim： （＋）Doxazosin is a long-lasting inhibitor of a1-adrenoceptors that is widely used to treat benign prostatic hyperplasia and lower urinary tract symptoms. In this study we investigated the stereoselective binding of doxazosin enantiomers to the plasma proteins of rats, dogs and humans in vitro. Methods： Human, dog and rat plasma were prepared. Equilibrium dialysis was used to determine the plasma protein binding of each enantiomer in vitro. Chiral HPLC with fluorescence detection was used to measure the drug concentrations on each side of the dialysis membrane bag. Results： Both the enantiomers were highly bound to the plasma proteins of rats, dogs and humans [（-）doxazosin： 89.4%-94.3%; （＋）doxazosin： 90.9%-95.4%]. （＋）Doxazosin exhibited significantly higher protein binding capacities than （-）doxazosin in all the three species, and the difference in the bound concentration （Cb） between the two enantiomers was enhanced as their concentrations were increased. Although the percentage of the plasma protein binding in the dog plasma was significantly lower than that in the human plasma at 400 and 800 ng/mL, the corrected percentage of plasma protein binding was dog〉human〉rat. Conclusion： （-）Doxazosin and （＋）doxazosin show stereoselective plasma protein binding with a significant species difference among rats, dogs and humans.     

Effects of capsaicin on oxidative modification of blood plasma proteins and arterial blood pressure in fructose-fed rats

The influence of the activation of capsaicin-sensitive nerves with capsaicin on the oxidative modification of blood plasma proteins and arterial blood pressure was studied in Wistar rats fed with 12.5% fructose in drinking water for 10 weeks. The obtained results indicate that fructose feeding induces an increase in the arterial blood pressure and the content of plasma blood protein carbonyl derivates. At the same time, in hypertensive rats, the stimulation of sensory nerves by capsaicin (1 mg/kg, i.p.) decreases the content of oxidized proteins in the plasma and normalizes the arterial blood pressure. It is suggested that capsaicin-sensitive nerves are involved in the regulation of oxidative destruction of proteins as well as in blood pressure control under metabolic disturbances produced by prolonged fructose feeding.     

Nonenzymatic glycation of plasma proteins in smokers

Glycation is known to play a key role in complications of many pathophysiological processes. The present study was carried out to assess whether there are abnormalities of nonenzymatic glycation of proteins in smokers. Fourteen current smokers and 10 healthy nonsmokers were enrolled for the present study. Fasting plasma glucose, insulin, fructosamine and total plasma glycated proteins were evaluated. A significant rise in the mean levels of fructosamine and total plasma glycated proteins were found in smokers when compared with controls. Significant difference in insulin values was observed between these two groups. When Pearson's correlation analysis was performed, no significant correlation was found between fasting plasma glucose with either fructosamine or total plasma glycated protein levels. These data suggest an increased glycation of proteins in smokers independent of glucose concentration.     

纤维喉镜下等离子治疗声带小结的临床观察

目的探讨纤维喉镜下进行低温等离子手术治疗声带小结的临床疗效。方法选取本院2009年1月～2010年12月纤维咽喉镜电视监控下行低温等离子刀治疗声带小结的患者74例,对临床治疗效果进行观察,并与保守治疗进行对比分析。结果低温等离子刀手术治疗痊愈45例(60.8%)、显效15例(20.3%)、有效14例(18.9%),总有效率为100.0%,与保守治疗相比痊愈率、显效率、有效率与总有效率均显著提高(P<0.05)。结论纤维喉镜监控下进行低温等离子手术治疗声带小结能够取得良好的临床效果,可作为保守治疗之后的首选治疗方法。     

In vivo kinetic analysis of covalent binding between N-acetyl-L-cysteine and plasma protein through the formation of mixed disulfide in rats

Purpose. This investigation was undertaken to study the relationship between plasma drug clearance and covalent protein-binding kinetics of N-acetyl-L-cysteine (NAC). Methods. NAC was intravenously administered to rats via a bolus injection or continuous infusion. Plasma concentrations of protein-unbound and total NAC were analyzed using a compartment model, taking into consideration of the protein binding process, and the apparent first-order binding and dissociation rate constants (k_on and k_off) were obtained. Results. Plasma total NAC after a bolus injection showed biphasic elimination with an inflection point at 1 hr. After 1 hr, NAC was largely present in the covalent protein-bound form. During the steady state of the infusion, approximately 30%-40% of plasma NAC bound with protein covalently. The k_on, k_off, and the elimination rate constant of protein-unbound drug (k_e) were 0.23, 0.57, and 4.3 hr^-1. The dissociation half-life of NAC from protein estimated from k_off was in agreement with the elimination half-life of plasma total NAC. This suggests that the dissociation of NAC from protein rate-limited the drug elimination in plasma (k_off < k_e). Conclusion. We demonstrated that plasma total drug clearance is kinetically limited by covalent protein binding. The compartmental model described here is useful for analyzing its kinetics in vivo.     

Conjugation of dinitrofluorobenzene to plasma proteins in vivo in the rat.

The extent of protein dinitrophenylation was determined in plasma and other tissues of anesthetized rats after administration of the model immunogen [3H]dinitrofluorobenzene (DNFB) (25 mg/kg; 5-25 microCi). DNFB was given by the intravenous, intraportal, intramuscular, or oral route. Irreversible binding was determined radiometrically after exhaustive solvent extraction of plasma or organ proteins. The extent of binding was high in plasma after parenteral administration (approximately 1% dose/ml plasma), but less (approximately 0.1% dose/ml) if DNFB was given orally. Low levels of radioactivity were bound irreversibly in liver (0.01-0.13% dose/g) and kidney (0.03-0.10% dose/g) and only residual amounts in other organs. Western blotting was used to identify target proteins in plasma, liver, and kidney using a specific antidinitrophenyl antiserum. No dinitrophenylation could be detected in liver or kidney samples, but strong recognition of two protein bands was observed in plasma. Bands with the same apparent molecular masses (67 and 44 kDa) were seen when DNFB was incubated with rat plasma in vitro. Preliminary evidence for these proteins being albumin and alpha 1-acid glycoprotein, respectively, is presented. The latter may be important for interindividual variability in immune responsiveness, because it is an acute phase protein whose levels fluctuate widely during disease states.