Structure-based approach for the study of thyroid hormone receptor binding affinity and subtype selectivity.

Thyroid hormone (TH) possesses the ability to lower cholesterol and improve cardiac performance, which have prompted the efforts to design analogs that can utilize the cholesterol-lowering property without adversely affecting heart function. In order to gain insights into the interaction mechanism for agonists at the active site of thyroid hormone receptor ß (TRß), quantitative structure-activity relationship (QSAR) models have been developed on TRß agonists, significant statistical coefficients were obtained (CoMFA, R(2)cv, .732), (CoMSIA, R(2)cv, .853), indicating the internal consistency of the models, the obtained models were further validated using the test set, the acquired R(2)pred values .7054 and .7129 were in good agreement with the experimental results. The key amino acids affecting ligand binding were identified by molecular docking, and the detailed binding modes of the compounds with different activities were also determined. Furthermore, molecular dynamics (MD) simulations were conducted to assess the reliability of the derived models and the docking results. Moreover, TH exerts significant physiological effects through modulation of the two human thyroid hormone receptor subtypes. Because TRß and TRα locate in different target cells, selective TR ligands would target specific tissues regulated by one receptor without affecting the other. Thus, the 3D information was analyzed to reveal the most relevant structural features involved in selectivity. The findings serve as the basis for further investigation into selective TRß/TRα agonists.

Elevated plasma D-dimer and hypersensitive C-reactive protein levels may indicate aortic disorders / Níveis plasmáticos elevados do dímero D e da proteína C reativa hipersensíveis podem indicar desordens aórticas

OBJECTIVE: D-dimer and C-reactive protein are of diagnostic and predictive values in patients have thrombotic tendency, such as vascular thrombosis, coronary artery disease and aortic dissection. However, the comparative study in these biomarkers between the patients with acute aortic dissection and coronary artery disease has not been sufficiently elucidated. METHODS: Consecutive surgical patients for acute type A aortic dissection (20 patients), aortic aneurysm (nine patients) or coronary artery disease (20 patients) were selected into this study. Plasma from preoperative blood samples and supernatant of aortic homogenate of the surgical specimens were detected for D-dimer and hypersensitive C-reactive protein (hs-CRP). RESULTS: Plasma D-dimer and hs-CRP values in type A aortic dissection or aortic aneurysm were much higher than in coronary artery disease patients or the healthy control (for D-dimer, aortic dissection: coronary artery disease, 0.4344 ± 0.2958 µg/ml vs. 0.0512 ± 0.0845 µg/ml, P < 0.0001; aortic dissection: healthy control, 0.4344 ± 0.2958 µg/ml vs. 0.1250 ± 0.1295 µg/ml, P = 0.0005; aortic aneurysm: coronary artery disease, 0.4200 ± 0.4039 µg/ml vs. 0.0512 ± 0.0845 µg/ml, P = 0.0013; and aortic aneurysm: healthy control, 0.4200 ± 0.4039 µg/ml vs. 0.1250 ± 0.1295 µg/ml, P = 0.0068; and for hs-CRP, aortic dissection: coronary artery disease, 4.400± 3.004 mg/L vs. 1.232±0.601 mg/L, P < 0.0001; aortic dissection:healthy control, 4.400 ± 3.004 mg/L vs. 0.790 ± 0.423 mg/L, P < 0.0001; aortic aneurysm: coronary artery disease, 2.314 ± 1.399 mg/L vs. 1.232 ± 0.601 mg/L, P = 0.0084; aortic aneurysm: healthy control, 2.314 ± 1.399 mg/L vs. 0.790 ± 0.423 mg/L, P = 0.0002; and coronary artery disease: healthy control, 1.232 ± 0.601 mg/L vs. 0.790 ± 0.423 mg/L, P = 0.0113). Besides, there were close correlations between plasma D-dimer and hs-CRP in overall (Y = 4.8798X + 0.8138, r² = 0.4497, r = 0.671, P < 0.001), aortic dissection ...

OBJETIVO: D-dímero e proteína C reativa são de valores de diagnóstico e preditivo em pacientes com tendência trombótica, como a trombose vascular, doença arterial coronária e dissecção aórtica. No entanto, o estudo comparativo desses biomarcadores entre os pacientes com dissecção aguda da aorta e doença arterial coronariana não foi suficientemente esclarecido. MÉTODOS: Pacientes cirúrgicos consecutivos foram selecionados para este estudo por tipo de dissecção aguda aórtica (20 pacientes), aneurisma da aorta (9 pacientes) ou doença arterial coronária (20 pacientes). O plasma a partir de amostras de sangue no pré-operatório e sobrenadante de homogenato de aorta dos espécimes cirúrgicos foi detectado para o D-dímero e proteína C reativa hipersensível. RESULTADOS: Os valores do plasma de D-dímero e proteína-C reativa em dissecção aórtica tipo A ou aneurisma da aorta foram muito superiores em pacientes com doença arterial coronariana ou de controles saudáveis (pelo D-dímero, dissecção aórtica: doença arterial coronariana, 0,4344 ± 0,2958 µg/ml vs 0,0512 ± 0,0845 µg/ml, P <0,0001; dissecção aórtica: controle saudável, 0,4344 ± 0,2958 µg/ml vs 0,1250 ± 0,1295 µg/ml, P = 0,0005; aneurisma da aorta: doença arterial coronariana, 0,4200 ± 0,4039 µg/ml vs 0,0512 ± 0,0845 µg/ml, P = 0,0013; e aneurisma de aorta: controle saudável, 0,4200 ± 0,4039 µg/ml vs. 0,1250 ± 0,1295 µg/ml, P = 0,0068 e para a hs-CRP, dissecção aórtica: doença arterial coronariana, 4,400 ± 3,004 mg/L vs. 1,232 ± 0,601 mg/L, P <0,0001; dissecção aórtica: grupo controle saudável, 4,400 ± 3,004 mg/L vs 0,790 ± 0,423 mg/L, P <0,0001; aneurisma da aorta: doença arterial coronariana, 2,314 ± 1,399 mg/L vs. 1,232 ± 0,601 mg/L, P = 0,0084; aneurisma da aorta: grupo controle saudável, 2,314 ± 1,399 mg/L vs. 0,790 ± 0,423 mg/L, P = 0,0002; e doença arterial coronariana: grupo controle saudável, 1,232 ± 0,601 mg/L versus 0,790 ± 0,423 mg/L, P = 0,0113). Além disso, houve correlações próximas ...

Dyslipidemic high-fat diet affects adversely bone metabolism in mice associated with impaired antioxidant capacity.

OBJECTIVE: The present study examined impacts of dyslipidemic high-fat diet on the bone antioxidant system and bone metabolism in growing mice. Furthermore, the relationship was studied between them. METHODS: Male C57BL/6 mice (4 wk old) were fed with normal diet, high-fat diet (HFD), or HFD supplemented with 0.1% antioxidant lipoic acid (LA). After 13-wk feeding, the markers of plasma lipids status, bone metabolism in plasma and in urine, and femora oxidative stress were measured. To provide molecular evidence for abnormal bone metabolism affected by HFD, bone cell-specific mRNA levels were tested by real-time quantitative polymerase chain reaction. Moreover, insulin-like growth factor I and tumor necrosis factor-alpha in plasma and their mRNA levels in femur were measured. RESULTS: The feeding dyslipidemic HFD induced both inhibitory bone formation reactions and enhancement of bone resorption reactions, accompanied by impaired bone antioxidant system, low levels of insulin-like growth factor I in plasma and in bone, and high levels of tumor necrosis factor-alpha in plasma but not in bone. In contrast, these alternatives were prevented completely or partially in mice fed LA supplement. Further, plasma propeptide of І collagen C-propeptide as a marker of bone formation was positively correlated with both total antioxidant capacity (r=0.683, P<0.001) and reduced glutathione/oxidized glutathione ratio (r=0.565, P<0.003) of bone. Cross-linked N-telopeptides of bone type І collagen as a marker of bone resorption was negatively correlated with both total antioxidant capacity (r=-0.753, P<0.001) and glutathione/oxidized glutathione ratio (r=-0.786, P<0.001). CONCLUSION: Dyslipidemia induces impaired bone antioxidant system. Oxidative stress could be an important mediator of hyperlipidemia-induced bone loss.

Antioxidative peptides derived from enzyme hydrolysis of bone collagen after microwave assisted acid pre-treatment and nitrogen protection.

This study focused on the preparation method of antioxidant peptides by enzymatic hydrolysis of bone collagen after microwave assisted acid pre-treatment and nitrogen protection. Phosphoric acid showed the highest ability of hydrolysis among the four other acids tested (hydrochloric acid, sulfuric acid and/or citric acid). The highest degree of hydrolysis (DH) was 9.5% using 4 mol/L phosphoric acid with a ratio of 1:6 under a microwave intensity of 510 W for 240 s. Neutral proteinase gave higher DH among the four protease tested (Acid protease, neutral protease, Alcalase and papain), with an optimum condition of: (1) ratio of enzyme and substrate, 4760 U/g; (2) concentration of substrate, 4%; (3) reaction temperature, 55 °C and (4) pH 7.0. At 4 h, DH increased significantly (P < 0.01) under nitrogen protection compared with normal microwave assisted acid pre-treatment hydrolysis conditions. The antioxidant ability of the hydrolysate increased and reached its maximum value at 3 h; however DH decreased dramatically after 3 h. Microwave assisted acid pre-treatment and nitrogen protection could be a quick preparatory method for hydrolyzing bone collagen.

Effects of duodenal redox status on calcium absorption and related genes expression in high-fat diet-fed mice.

OBJECTIVE: This study investigated whether duodenal redox imbalance induced by high-fat diet (HFD) influenced expression of genes involved in transcellular calcium absorption, thus leading to reduced intestinal calcium absorption. METHODS: Male C57BL/6 mice were randomly assigned to one of four groups with eight mice in each group. The control group consumed an ordinary diet (4.9% fat, w/w). The other three groups were fed a HFD (21.2% fat), the HFD plus 0.1% lipoic acid, or the HFD plus an additional 0.9% calcium supplement. After 9 wk, plasma and duodenal oxidative stress biomarkers including malondialdehyde, superoxide dismutase, catalase, total antioxidant capacity, reduced glutathione/oxidized glutathione ratio, and reactive oxygen species were examined. The intestinal calcium absorption state was evaluated through examining the calcium balance, bone mineral density, and calcium metabolism biomarkers. Furthermore, quantitative reverse transcription-polymerase chain reaction was carried out to analyze the changes in expression of transcellular calcium absorption-related genes. RESULTS: The HFD induced marked decreases in intestinal calcium absorption and bone mineral density of the whole body, accompanied by redox imbalance and increased oxidative damage in duodenum; duodenal expression of calbindin-D(9K), plasma membrane calcium ATPase (PMCA(1b)), and sodium-calcium exchanger was significantly down-regulated by 1.9-, 2.7-, and 1.5-fold, respectively. Furthermore, duodenal glutathione and oxidized glutathione (GSH/GSSG) ratios were strongly positively correlated with the apparent calcium absorption rate and the expression of PMCA(1b) and Calbindin-D(9K), whereas reactive oxygen species levels were negatively correlated with them. CONCLUSION: Our results demonstrated that a HFD-induced duodenal oxidation state could significantly down-regulate expression of calbindin-D(9K), PMCA(1b), and sodium-calcium exchanger, thus causing an inhibitory effect on intestinal calcium absorption.

Reactive oxygen species serve as signals mediating glucose-stimulated somatostatin secretion from cultured rat gastric primary D-cells.

Somatostatin plays an important role in glucose homeostasis. It is normally secreted in response to glucose and ATP generation is believed to be the key transduction signal of glucose-stimulated somatostatin secretion (GSSS). However, in the present study, in cultured rat gastric primary D-cells, GSSS was accompanied by increases in cellular reactive oxygen species (ROS). GSSS is dependent on the cellular ROS and independently of the ATP production linked to glucose metabolism. The antioxidant, alpha-lipoic acid or catalase inhibitor, 3-aminotriazole can influence the intracellular calcium concentration and abolish or further elevate GSSS. It is suggested that ROS production may serve as a signal modulating the necessary Ca(2+) recruitment for GSSS. Since somatostatin is thought to exert broad regulatory functions on gastrointestinal physiology and nutrient intake, the interaction with ROS may lead to potential targets for mediating nutrition and energy homeostasis.

Effect of somatostatin analog on high-fat diet-induced metabolic syndrome: involvement of reactive oxygen species.

Oxidative stress plays an important role in overnutrition-induced metabolic syndrome. Somatostatin (SST) inhibits a wide variety of physiologic functions in the gastrointestinal tract, which may in turn control the levels of reactive oxygen species (ROS) derived from ingestion of macronutrients. In this study, the involvement of SST in the progression of metabolic syndrome in response to a high-fat diet (HFD) was investigated. Male C57BL/6 mice were fed either a normal diet (4.89% fat) or a high-fat diet (21.45% fat) for 4 weeks. The SST analog octreotide (20 microg/kg/day) was then administered intraperitoneally to half of the HFD mice throughout the 10-day experimental period. Body weight, adipose tissue weight, gastric acidity, total bile acid, and lipase activity were measured. Plasma lipid, glucose, insulin, SST, the levels of ROS and GSH/GSSG, and lipid peroxidation in the stomach, small intestine, pancreas, and liver were also evaluated. Following HFD intake for 38 days, a decrease in the plasma levels of SST and GSH/GSSG ratio was observed, while there was an increase in body weight, adipose tissue weight, plasma glucose, triglyceride, and levels of ROS and lipid peroxidation of the stomach, small intestine, pancreas, and liver. However, simultaneous administration of SST analog octreotide to HFD-fed mice significantly reduced ROS production of the digestive system and resulted in the improvement of all the aforesaid adverse changes, suggesting the involvement of SST in the progression of HFD-induced metabolic syndrome.

Microarray analysis of high-glucose diet-induced changes in mRNA expression in jejunums of C57BL/6J mice reveals impairment in digestion, absorption.

Long term intake of high-glucose diet (HGD) may induce many diseases such as dyslipidemia, fatty liver and diabetes disease. Most of the research for molecular mechanisms of the association between HGD and the above diseases focus on the metabolism of glucose and lipid. However, there are few studies on molecular mechanism of the effect of HGD on digestion and absorption. We used HGD (containing 20% glucose) to feed C57BL/6J mice for 4 weeks, detected the expressions of 13,098 genes in jejunums of C57BL/6J mice with DNA microarray. Microarray analysis showed the expression of genes related to digestive enzyme, gastrointestinal peptide and nutrient transporters were significantly changed, which indicated that HGD induced the suppression of digestive enzyme gene expression, attenuation of alimentary tract movement and nutrient transportation. In one word, the microarray analysis suggested that HGD impaired the function of digestion and absorption in jejunum of C57BL/6J mice. We validated our microarray findings by conducting real-time RT-PCR assays on selected genes and detecting the activities of disaccharidases such as lactase, maltase and sucrase in jejunum of C57BL/6J mice.

Design and analysis of structure-activity relationship of novel antimicrobial peptides derived from the conserved sequence of cecropin.

We have de novo designed four antimicrobial peptides AMP-A/B/C/D, the 51-residues peptides, which are based on the conserved sequence of cecropin. In the present study, the four peptides were chemically synthesized and their activities assayed. Their secondary structure, amphipathic property, electric field distribution and transmembrane domain were subsequently predicted by bioinformatics tools. Finally, the structure-activity relationship was analyzed from the results of activity experiments and prediction. The results of activity experiments indicated that AMP-B/C/D clearly possessed excellent broad-spectrum activity against bacteria, whereas AMP-A was almost inactive against most of the bacterial strains tested. AMP-B/C/D showed more potent activity against Gram-positive bacteria than against Gram-negative bacteria. By utilizing bioinformatics analysis tools, we found that the secondary structure of the four cation peptides was mainly alpha-helix, and the result of CD spectrum also displayed that all the peptides had considerable alpha-helix in the presence of either 50% TFE or SDS micelles. AMP-C showed much better activity than other peptides against most of the bacteria tested, owing to its remarkable cation property and the amphipathic character of its N-terminal. The study of structure-activity relationship of the designed peptides confirmed that amphipathic structure and high net positive charge were prerequisites for maintaining their activities.

Nonopsonic phagocytosis of Lactobacilli by mice Peyer's patches' macrophages.

The ingestion of lactobacilli is of great importance for the probiotic effect of host gut Peyer's patches (PPs) macrophages. The present study is in time focus on the investigation of the factors determining the ingestion of lactobacilli by PPs macrophages. Physicochemical properties of cell surface and adhesive property of nine Lactobacillus strains were examined in the present work. The association of the bacteria with PPs macrophage was checked with macrophage monolayers on coverslips. The influence of lactobacilli on macrophages phagocytic capacity was also investigated with a neutral red uptake assay in vitro. The results show that the macrophages could ingest lactobacilli in a strain dependent manner, and the most ingested strain is L. plantarum Lp6 compared to other tested strains, which displayed strain specific enhancement on the phagocytic activity of PPs macrophages. And there is no correlation between the physicochemical or adhesive properties of the cell surface and the ingestion. The association of L. plantarum Lp6 with PPs macrophage could be decreased by Protease K treatment. Surface proteins of L. plantarum Lp6 could promote the ingestion of fluorescent latex beads by PPs macrophages. In conclusion, the hydrophobicity of the cell surface might not be the key factor determining the association of lactobacilli with PPs macrophages. Cell surface proteins are the media for the binding L. plantarum Lp6 to macrophages.

Novel angiotensin I-converting enzyme inhibitory peptides isolated from Alcalase hydrolysate of mung bean protein.

Mung bean protein isolates were hydrolyzed for 2 h by Alcalase. The generated hydrolysate showed angiotensin I-converting enzyme (ACE) inhibitory activity with the IC(50) value of 0.64 mg protein/ml. Three kinds of novel ACE inhibitory peptides were isolated from the hydrolysate by Sephadex G-15 and reverse-phase high performance liquid chromatography (RP-HPLC). These peptides were identified by amino acid composition analysis and matrix assisted-laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF MS/MS), as Lys-Asp-Tyr-Arg-Leu, Val-Thr-Pro-Ala-Leu-Arg and Lys-Leu-Pro-Ala-Gly-Thr-Leu-Phe with the IC(50) values of 26.5 microM, 82.4 microM and 13.4 microM, respectively.

Transcriptome profiling, molecular biological, and physiological studies reveal a major role for ethylene in cotton fiber cell elongation.

Upland cotton (Gossypium hirsutum) produces the most widely used natural fibers, yet the regulatory mechanisms governing fiber cell elongation are not well understood. Through sequencing of a cotton fiber cDNA library and subsequent microarray analysis, we found that ethylene biosynthesis is one of the most significantly upregulated biochemical pathways during fiber elongation. The 1-Aminocyclopropane-1-Carboxylic Acid Oxidase1-3 (ACO1-3) genes responsible for ethylene production were expressed at significantly higher levels during this growth stage. The amount of ethylene released from cultured ovules correlated with ACO expression and the rate of fiber growth. Exogenously applied ethylene promoted robust fiber cell expansion, whereas its biosynthetic inhibitor l-(2-aminoethoxyvinyl)-glycine (AVG) specifically suppressed fiber growth. The brassinosteroid (BR) biosynthetic pathway was modestly upregulated during this growth stage, and treatment with BR or its biosynthetic inhibitor brassinazole (BRZ) also promoted or inhibited, respectively, fiber growth. However, the effect of ethylene treatment was much stronger than that of BR, and the inhibitory effect of BRZ on fiber cells could be overcome by ethylene, but the AVG effect was much less reversed by BR. These results indicate that ethylene plays a major role in promoting cotton fiber elongation. Furthermore, ethylene may promote cell elongation by increasing the expression of sucrose synthase, tubulin, and expansin genes.

Direct spectrophotometric measurement of angiotensin I-converting enzyme inhibitory activity for screening bioactive peptides.

A direct, extraction-free spectrophotometric assay was developed for determination of angiotensin I-converting enzyme activity (ACE) in the presence of ACE inhibitors using hippuryl-l-histidyl-l-leucine (HHL) as the ACE-specific substrate. This method relies on previously published spectrophotometric determination of hippuric acid (HA) content in the urine, the method of which was based on the specific colorimetric reaction of HA with benzene sulfonyl chloride (BSC) in the presence of quinoline. The proposed ACE inhibition assay was applied to the measurement of the ACE inhibitory activity of Captopril. IC(50) value of Captopril corresponded well with literature data. Furthermore, Alcalase hydrolysates of mung bean and rice protein isolates were assessed for ACE inhibitory activity by this method. These two hydrolysates showed high ACE inhibitory activity. This method proposed here was shown to be direct, sensitive, accurate, reproducible, and less expensive without separation of HA from ACE reaction mixture, and can be used for the screening of ACE inhibitory peptides derived from food proteins.

Distinct immune response induced by peptidoglycan derived from Lactobacillus sp.

AIM: To analyze the distinct immune responses induced by Lactobacillus peptidoglycan (PG). METHODS: BALB/c mice were intraperitoneally injected with PG once a day for three consecutive days. Peritoneal macrophage and splenocyte mRNA was extracted and the gene expression profile was studied using high-density oligonucleotide microarrays. Inhibitory effects of Lactobacillus PG on colon tumor tissue were studied in vitro and in vivo. RESULTS: The gene expression profiles revealed that the TLR-NF-kappaB; and Jak-STAT signaling pathways were highly activated. An inflammatory phenotype was induced when peritoneal macrophages were initially exposed to Lactobacillus PG and switched to a more complex phenotype when BALB/c mice were treated with three doses of Lactobacillus PG. A protective physiological inflammatory response was induced after three consecutive days of PG treatment. It was tending toward Th1 dominant immune response. Lactobacillus PG also appeared to induce a significant in vivo anti-colon tumor effect. CONCLUSION: Lactobacillus PG is responsible for certain immune responses induced by Lactobacilli. Anti-tumor effects of Lactobacilli are likely to attribute to the activation of macrophages by PG expressed on the bacterial cell surface.

[Insect antibacterial peptides and its progress in advance on genetic engineering].

Insect antibacterial peptides produced are kinds of bioactive peptides in hameolymph hen insect has been immunized. These peptides have the wide range of antibacterial,antiviral spectrum and inhibiting growth of tumor cell. The types of antibacterial peptides and its physiological activities,cloning and expression of the genes and transgenetic research are summarized. Its application on medicine and gene engineering are prospected.