Design and size control of uniform zeolite nanocrystals synthesized in adjustable confined voids formed by recyclable monodisperse polymer spheres.
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Retraction Notice↗
Biomedical subjects
G Tian
Publications and source records attributed to G Tian.
Detection of Hong Kong 97-like H5N1 influenza viruses from eggs of Vietnamese waterfowl.
Three H5N1 influenza viruses were isolated from shell washes of duck and goose eggs confiscated from travelers coming from Vietnam. All eight gene segments of these viruses share high sequence identity with the H5N1 avian influenza viruses that caused outbreaks in poultry and humans in Hong Kong in 1997. Animal studies indicate that these isolated viruses are able to replicate in mouse lung and could be found in the organs of ducks without causing any clinical signs or death. However, the viruses are highly pathogenic for chickens. Although the source of these recently isolated Hong Kong 97-like H5N1 viruses is undetermined, their detection in the egg shell of duck and goose suggests that this particular genotype of H5N1 virus may have re-emerged in nature or may have been circulating continuously.
Animals↗
Effect of long-term application of biosolids for land reclamation on surface water chemistry.
Biosolids are known to have a potential to restore degraded land, but the long-term impacts of this practice on the environment, including water quality, still need to be evaluated. The surface water chemistry (NO3-, NH4+, and total P, Cd, Cu, and Hg) was monitored for 31 yr from 1972 to 2002 in a 6000-ha watershed at Fulton County, Illinois, where the Metropolitan Water Reclamation District of Greater Chicago was restoring the productivity of strip-mined land using biosolids. The mean cumulative loading rates during the past 31 yr were 875 dry Mg ha(-1) for 1120-ha fields in the biosolids-amended watershed and 4.3 dry Mg ha(-1) for the 670-ha fields in the control watershed. Biosolids were injected into mine spoil fields as liquid fertilizer from 1972 to 1985, and incorporated as dewatered cake from 1980 to 1996 and air-dried solids from 1987 to 2002. The mean annual loadings of nutrients and trace elements from biosolids in 1 ha were 735 kg N, 530 kg P, 4.5 kg Cd, 30.7 kg Cu, and 0.11 kg Hg in the fields of the biosolids-amended watershed, and negligible in the fields of the control watershed. Sampling of surface water was conducted monthly in the 1970s, and three times per year in the 1980s and 1990s. The water samples were collected from 12 reservoirs and 2 creeks receiving drainage from the fields in the control watershed, and 8 reservoirs and 4 creeks associated with the fields in the biosolids-amended watershed for the analysis of NO3- -N (including NO2- N), NH4+-N, and total P, Cd, Cu, and Hg. Compared to the control (0.18 mg L(-1)), surface water NO3- -N in the biosolids-amended watershed (2.23 mg L(-1)) was consistently higher; however, it was still below the Illinois limit of 10 mg L(-1) for public and food-processing water supplies. Biosolids applications had a significant effect on mean concentrations of ammonium N (0.11 mg L(-1) for control and 0.24 mg L(-1) for biosolids) and total P (0.10 mg L(-1) for control and 0.16 mg L(-1) for biosolids) in surface water. Application of biosolids did not increase the concentrations of Cd and Hg in surface water. The elevation of Cu in surface water with biosolids application only occurred in some years of the first decade, when land-applied sludges contained high concentrations of trace metals, including Cu. In fact, following the promulgation of 40 CFR Part 503, the concentrations of all three metals fell below the method detection level (MDL) in surface water for nearly all samplings. Nitrate in the surface water tends to be higher in spring, and ammonium, total P, and total Hg in summer and fall. Mean nitrate, ammonium, and total phosphorus concentrations were found to be greater in creeks than reservoirs. The results indicate that application of biosolids for land reclamation at high loading rates from 1972 to 2002, with adequate runoff and soil erosion control, had only a minor impact on surface water quality.
Metals↗
Development of a recombinant fowlpox virus vector-based vaccine of H5N1 subtype avian influenza.
The genetic stability of the recombinant fowlpox virus (named rFPV-HA-NA) was confirmed by serial passage on chicken embryo fibroblast (CEF) cells. The immune efficacy, safety, the minimum immunising dose, the time of immunity induced and the immune duration of the vector-based vaccine was evaluated in specific-pathogen-free (SPF) chickens. The recombinant virus vaccine containing 100 plaque form units (PFU) could induce complete protection against challenge with H5N1 highly pathogenic avian influenza virus (HPAIV). The immune efficacy, protecting chickens from clinical signs and death after challenge, was obtained one week after the immunisation with this vaccine. Protective immunity could last for 40 weeks post-immunisation. So the recombinant fowlpox vaccine is a safe and highly effective gene engineering vaccine candidate, and will be used to prevent H5 subtype avian influenza in the future.
Animals↗
The evolution of H5N1 influenza viruses in ducks in southern China.
The pathogenicity of avian H5N1 influenza viruses to mammals has been evolving since the mid-1980s. Here, we demonstrate that H5N1 influenza viruses, isolated from apparently healthy domestic ducks in mainland China from 1999 through 2002, were becoming progressively more pathogenic for mammals, and we present a hypothesis explaining the mechanism of this evolutionary direction. Twenty-one viruses isolated from apparently healthy ducks in southern China from 1999 through 2002 were confirmed to be H5N1 subtype influenza A viruses. These isolates are antigenically similar to A/Goose/Guangdong/1/96 (H5N1) virus, which was the source of the 1997 Hong Kong "bird flu" hemagglutinin gene, and all are highly pathogenic in chickens. The viruses form four pathotypes on the basis of their replication and lethality in mice. There is a clear temporal pattern in the progressively increasing pathogenicity of these isolates in the mammalian model. Five of six H5N1 isolates tested replicated in inoculated ducks and were shed from trachea or cloaca, but none caused disease signs or death. Phylogenetic analysis of the full genome indicated that most of the viruses are reassortants containing the A/Goose/Guangdong/1/96-like hemagglutinin gene and the other genes from unknown Eurasian avian influenza viruses. This study is a characterization of the H5N1 avian influenza viruses recently circulating in ducks in mainland China. Our findings suggest that immediate action is needed to prevent the transmission of highly pathogenic avian influenza viruses from the apparently healthy ducks into chickens or mammalian hosts.
Animals↗
Structural determinants for potent, selective dual site inhibition of human pp60c-src by 4-anilinoquinazolines.
The kinetic mechanisms for the inhibition of pp60(c-src) tyrosine kinase (Src TK) by 4-anilinoquinazolines, an important class of chemicals as protein kinase inhibitors, were investigated. 4-Anilinoquinazolines with a bulky group at the 4'-position of the anilino group were shown to be competitive with both ATP and peptide, whereas molecules lacking such a bulky group only displayed an inhibition pattern typical of those competitive with ATP and noncompetitive with peptide. Modifications of the substituents on the carbocyclic ring did not perturb the inhibition pattern although the affinities of these modified inhibitors for Src TK were affected. Structural modeling of Src TK with inhibitor and peptide substrate bound indicated a direct atomic conflict between the bulky 4-position group and the hydroxy of the peptide tyrosyl to which the gamma-phosphate of ATP is transferred during the kinase reaction. This atomic conflict would likely prevent simultaneous binding of both inhibitor and peptide, consistent with the observed kinetic competitiveness of the inhibitor with peptide. The dual site inhibitors appeared to have both enhanced potency and selectivity for Src TK. One such inhibitor, 4-(4'-phenoxyanilino)-6,7-dimethoxyquinazoline, had a 15 nM potency against Src TK and was selective over receptor tyrosine kinases VEGFR2 by 88-fold and C-fms by 190-fold.
Adenosine Triphosphate↗
Structural characterization of the glycan part of glycoconjugate LbGp2 from Lycium barbarum L.
A glycoconjugate with pronounced immunoactivity, designated as LbGp2, was isolated from the fruit of Lycium barbarum L. and purified to homogeneity by gel-filtration. Its carbohydrate content is up to 90.71% composed of Ara, Gal and amino acids. The molecular weight is 68.2 kDa as determined by size exclusive chromatography (SEC). The complete structure of the repeat unit of the glycan of LbGp2 was elucidated based on glycosidic linkage analysis, total acid hydrolysis, partial acid hydrolysis, 1H and 13C NMR spectroscopy. According to the experiments, the glycan possesses a backbone consisting of (1-->6)-beta-galactosyl residues, about fifty percent of which are substituted at C-3 by galactosyl or arabinosyl groups and the major nonreducing end being made of Ara (1 -->.
Carbohydrate Conformation↗
Linear relationships between the ligand binding energy and the activation energy of time-dependent inhibition of steroid 5alpha-reductase by delta 1-4-azasteroids.
The inhibition of steroid 5alpha-reductase (5AR) by Delta(1)-4-azasteroids is characterized by a two-step time-dependent kinetic mechanism where inhibitor combines with enzyme in a fast equilibrium, defined by the inhibition constant K(i), to form an initial reversible enzyme-inhibitor complex, which subsequently undergoes a time-dependent chemical rearrangement, defined by the rate constant k(3), leading to the formation of an apparently irreversible, tight-binding enzyme-inhibitor complex (Tian, G., Mook, R. A., Jr., Moss, M. L., and Frye, S. V. (1995) Biochemistry 34, 13453-13459). A detailed kinetic analysis of this process with a series of Delta(1)-4-azasteroids having different C-17 substituents was performed to understand the relationships between the rate of time-dependent inhibition and the affinity of the time-dependent inhibitors for the enzyme. A linear correlation was observed between ln(1/K(i)), which is proportional to the ligand binding energy for the formation of the enzyme-inhibitor complex, and ln(1/(k(3)/K(i))), which is proportional to the activation energy for the inhibition reaction under the second order reaction condition, which leads to the formation of the irreversible, tight-binding enzyme-inhibitor complex. The coefficient of the correlation was -0.88 +/- 0.07 for type 1 5AR and -1.0 +/- 0.2 for type 2 5AR. In comparison, there was no obvious correlation between ln(1/K(i)) and ln(1/k(3)), which is proportional to the activation energy of the second, time-dependent step of the inhibition reaction. These data are consistent with a model where ligand binding energies provided at C-17 of Delta(1)-4-azasteroids is fully expressed to lower the activation energy of k(3)/K(i) with little perturbation of the energy barrier of the second, time-dependent step.
3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
Simultaneous antegrade/retrograde cardioplegia protects myocardium distal to a coronary occlusion: a study in isolated pig hearts.
This study was designed to assess the effects of simultaneous antegrade/retrograde cardioplegia (SARC) on myocardial perfusion and energy metabolism in the region supported by the occluded left anterior descending artery (LAD) in isolated pig hearts. It was found that injection of Gd-DTPA into the aorta during antegrade cardioplegia (AC) did not result in signal increase in the LAD region on T(1)-weighted images. During SARC, however, Gd-DTPA was detected in the LAD region with the contrast agent injected into the aorta and the coronary sinus (CS), respectively. This suggests that SARC delivered blood cardioplegia to the jeopardized myocardium through both arterial and venous perfusion routes. Moreover, localized (31)P spectra showed that occlusion of the LAD during AC resulted in severe ischemic changes in the LAD myocardium and the abnormal metabolic changes were completely abolished by use of SARC. Finally, recovery of myocardial contractile function during reperfusion in the hearts subjected to SARC was significantly better compared to those arrested with AC alone. It was concluded that the myocardium distal to a coronary occlusion can be fully protected by use of SARC.
Animals↗
Factors affecting ammonia volatilisation from a rice-wheat rotation system.
Some of the major factors influencing ammonia volatilisation in a rice wheat rotation system were studied. A continuous airflow enclosure method was used to measure NH3 volatilisation in a field experiment at an agricultural college in Jiangsu Province. The five treatments comprised application rates of 0, 100, 200 or 300 kg N ha(-1) as urea, per growing season with rice straw amendment when wheat was sown, and 200 kg N ha(-1) without rice straw amendment. There were three replicates in a randomised block design. Ammonia volatilisation was measured immediately after urea application in the three consecutive years 1995 to 1997. The results show that N losses through NH3 volatilisation accounted for 4-19% of N applied during the wheat growing season and for 5-11% during the rice growing season. Ammonia volatilisation was affected significantly by soil moisture and temperature before and after fertiliser application during the wheat growing season. The ratio of volatilised NH3-N to applied N after urea application during the rice growing season was as follows: top-dressing at the onset of tillering > top-dressing at the start of the booting stage > basal fertilization. The results also show that the amount of N lost through NH3 volatilisation increased with increasing N application rate, but the ratio to applied N was not affected significantly by N application rate. Amendment with rice straw had no significant effect on NH3 volatilisation.
Agriculture↗
Effect on myocardial perfusion of simultaneous delivery of cardioplegic solution through a single coronary artery and the coronary sinus.
OBJECTIVE: This study was to determine whether simultaneous antegrade-retrograde cardioplegia through a single coronary artery and the coronary sinus provides sufficient and homogeneous perfusion to the heart. METHODS: Simultaneous antegrade-retrograde cardioplegia was conducted in 7 isolated pig hearts through the coronary sinus in conjunction with the left anterior descending artery, the left circumflex artery, and the right coronary artery, respectively. The efficacy of simultaneous antegrade-retrograde cardioplegia for myocardial perfusion was assessed by monitoring the distribution of magnetic resonance contrast agent and measuring the effluent from the venting coronary arteries. RESULTS: Injection of contrast agent into a perfusing artery during simultaneous antegrade-retrograde cardioplegia resulted in increased image signal intensity not only in the territory of the perfusing artery but also in the areas normally served by the other 2 venting arteries (including the right ventricular wall). The myocardium in the territories of the 2 venting arteries was lightened with contrast agent given into the coronary sinus during simultaneous antegrade-retrograde cardioplegia. Myocardium in the perfusing artery territory and right ventricular wall remained dark. Moreover, a significant amount of effluent was collected from the venting arteries during simultaneous antegrade-retrograde cardioplegia: 4.7 to 7.8 mL/min from the right coronary artery; 10.5 to 17.7 mL/min from the left anterior descending artery; and 9.7 to 15.2 mL/min from the left circumflex coronary artery. CONCLUSIONS: Simultaneous antegrade-retrograde cardioplegia through a single coronary artery and the coronary sinus provides homogeneous perfusion to the entire heart. During simultaneous antegrade-retrograde cardioplegia, arterial flow supports its own designated myocardium, as well as adjacent myocardium normally served by the venting arteries; the arterial route also supports the right ventricular free wall when the right coronary artery is vented. Venous perfusion of simultaneous antegrade-retrograde cardioplegia mainly supports myocardium in the territories of the venting arteries and does not perfuse the right ventricular free wall. Blood flow delivered to myocardium normally supported by the venting arteries is believed to be sufficient to prevent ischemic injury.
Animals↗
Contrast agent distribution in microvascular damage of infarcted pig myocardium.
PURPOSE: We determined whether reperfusion damage was sufficient to allow extravasation of a large molecular weight contrast agent into infarcted pig myocardium. MATERIAL AND METHODS: Five pig hearts were subjected to in situ occlusion of the left anterior descending coronary artery (2 h) followed by reperfusion (1 h). The hearts were excised and perfused in the Langendorff mode for ex vivo MR imaging. Polylysine-Gd-DTPA (50,000 Da) and Gd-DTPA (500-700 Da) were injected into the aorta (alternately) and followed by measurements of T1 relaxation and mean transit time (MTT). RESULTS: In the normal myocardium, MTT of Gd-DTPA (56.8+/-23.2 s) was significantly (p=0.02) longer than that of polylysine-Gd-DTPA (29.0+/-7 s). However, both normal and infarcted myocardium showed similar MTT (29.0+/-7.0 vs. 28.0+/-5.0 s, p>0.05) when using polylysine-Gd-DTPA. CONCLUSION: The results indicate that the permeability of capillaries to polylysine-Gd-DTPA was not significantly higher in infarcted regions of the myocardium compared to normal tissue. However, infarcted myocardium displayed an increased permeability to the small molecular weight Gd-DTPA. We conclude that microvascular damage may not be sufficient to allow the extravasation of polylysine-Gd-DTPA in infarcted myocardium.
Animals↗
The change and significance of the Na+-K+-ATPase alpha-subunit in ouabain-hypertensive rats.
Ouabain has recently been identified as an endogenous Na+-K+ pump inhibitor having a close association with hypertension. However, some patients with hypertention do not show high levels of endogenous ouabain (EO), and patients with high EO levels do not necessarily suffer from hypertention. It is believed that the Na+-K+-ATPase activity in essential hypertension does not undergo homogenous change. The present study was designed, therefore, to investigate the expression and the significance of the Na+-K+-ATPase alpha-subunit isoforms in kidney tissue in ouabain-hypertensive rats. Ouabain was administered chronically to establish a model of ouabain-hypertensive rats. Biochemical analysis, cytobiology and sABC immunohistochemistry were they used to assay for expression of Na+-K+-ATPase alpha-subunit isoforms in kidney tissue. After the first week of receiving ouabain, 65% (n=13) of rats had hypertension. After the second week, the blood pressure of these 13 hypertensive rats was increased significantly compared to the baseline and control levels (p<0.05). The plasma renin activity was normal, and angiotensin II and aldosterone levels were increased significantly in these rats (p<0.05). But in the other 35% (n=7) of rats of the experimental group, there was no apparent increase in blood pressure after receiving ouabain. The plasma ouabain level in the non-hypertensive subgroup was significantly higher than that in the hypertensive subgroup, but the 86Rb intake and the number of 3H-ouabain binding sites did not decrease. The Na+-K+-ATPase activity showed non-homogeneous changes. In hypertensive rats, the expression levels of ouabain paralleled the degree of hypertension (r=0.88, p<0.05). The positive granules were mainly scattered in the cytoblastoma of the reticular zone of adrenal cortex. There were thus different levels of expression of Na+-K+-ATPase alpha-subunit isoforms in this model. In the hypertension subgroup the alpha1 was most strongly expressed, followed by the alpha2 and alpha3 isforms. But in the non-hypertensive subgroup the order was alpha3 > alpha2 > alpha1. The positive granular was mainly scattered in the convoluted tubules of the kidney. These results suggest that the high level of ouabain and the change of the Na+-K+-ATPase alpha-subunit isoforms may play a critical role in hypertension.
Adrenal Glands↗
Identifying substrates for endothelium-specific Tie-2 receptor tyrosine kinase from phage-displayed peptide libraries for high throughput screening.
The peptide substrate specificity of Tie-2 was probed using the phage display method in order to identify efficient substrate for high throughput screening. Two random peptide libraries, pGWX3YX4 and pGWX4YX4, were constructed, in which all twenty amino acid residues were represented at the X positions flanking the fixed tyrosine residue Y. A fusion protein of GST and the catalytic domain of human Tie-2 was used to perform the phage phosphorylation. The phosphorylated phage particles were enriched by panning over immobilized anti-phosphotyrosine antibody pY20 for a total of 5 rounds. Four phage clones (3T61, 3T68, C1-90 and D1-15) that express a peptide sequence that can be phosphorylated by the recombinant catalytic domain of human Tie-2 were identified. Synthetic peptides made according to the sequences of the 4 selected clones from the two libraries, which had widely different sequences, were active substrates of Tie-2. Kinetic analysis revealed that D1-15 had the best catalytic efficiency with a k(cat)/K(m) of 5.9x10(4) M(-1) s(-1). Three high throughput screening assay formats, dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA), radioactive plate binding (RPB) and time-resolved fluorescent resonance energy transfer (TR-FRET) were developed to assess the suitability of these phage display selected peptides in screening Tie-2 inhibitors. Three out of four peptides were functional in the DELFIA assay and D1-15 was functional in the TR-FRET assay.
Amino Acid Sequence↗
Serum granulocyte colony-stimulating factor in patients with chronic renal failure.
OBJECTIVE: To gain a better understanding of the regulatory mechanism and kinetic behaviour of granulocyte colony-stimulating factor (G-CSF). METHODS: An enzyme-linked immunosorbent assay (ELISA) method was used to detect serum G-CSF in 61 patients with chronic renal failure +/- long-term hemodialysis and 30 normal controls. RESULTS: Serum G-CSF levels in CRF patients were significantly higher than in normal controls. Eighty percent of patients had detectable G-CSF and serum G-CSF levels were 566.40 +/- 207.98 ng/L in non-hemodialyzed (non-HD) patients. The detectable percentage in hemodialyzed patients was 93.33%, serum G-CSF levels in pre-HD and post-HD patients were 1255.36 +/- 611.25 ng/L and 1151.61 +/- 599.47 ng/L respectively. Serum G-CSF levels in HD patients were slightly higher than in non-HD patients, but no significant difference was found between the two groups. No difference was found between the G-CSF values obtained in pre-HD and post-HD patients. There was no relationship between G-CSF levels and WBC, BUN or Scr (P > 0.05). CONCLUSION: The high value of G-CSF in patients with CRF may be caused by a decrease in G-CSF clearance and/or an increase in G-CSF release.
Adolescent↗
[A prospective study of histological changes after AraAMP treatment in patients with chronic hepatitis B infection].
OBJECTIVE: To investigate the histological changes in liver biopsy tissue induced by AraAMP therapy for 50 days in patients with chronic hepatitis B infection. METHODS: Eleven patients were enrolled into this prospective study. All the patients had liver biopsy performed within 1 week before starting AraAMP therapy. A second liver biopsy was taken for comparison six months after the end of therapy. Blinded biopsies were scored according to Knodell's histology activity index (HAI), and examined for HBeAg and alpha-smooth muscle actin with immunohistochemistry as well as HBV DNA by using in situ hybridization. RESULTS: Histological improvement of >or=2 points decrease in the necroinflammatory HAI scores was seen in 8 of the 11 (72.7%) of patients after treatment. In these patients histological assessment revealed a significant improvement in intralobular inflammation and fibrosis as compared with pretreatment values(P < 0.05). There was significant difference of HAI changes in 6 cases graded as G3 based on the degree of periportal interface hepatitis and spotty parenchymal injury, but not in 5 cases graded as G2. HBeAg disappeared from liver tissue in 4 of the 9 cases and a significant reduction of activated liver stellate cells was demonstrated in the second biopsy(P = 0.018). Of the nine cases with HBV DNA positive at the first biopsy with in situ hybridization examination, 4 were negative at the second biopsy. CONCLUSION: Significant improvement in intralobular inflammation and fibrosis can be observed in liver tissue from patients with chronic hepatitis B infection treated with AraAMP.
Adolescent↗
Separation of tanshinones from Salvia miltiorrhiza Bunge by high-speed counter-current chromatography using stepwise elution.
High-speed counter-current chromatography (HSCCC) was successfully used for isolation and purification of tanshinones from the roots of Salvia miltiorrhiza Bunge by stepwise elution. A set of three solvent systems and other experimental conditions were determined by analytical HSCCC. Using the optimized conditions, the preparative HSCCC separation was performed on 50 mg of crude light petroleum extract yielding pure tanshinones of tanshinone HA (7 mg), tanshinone I (3 mg) and cryptotanshinone (4 mg) all at purities of over 95% in a single run.
Abietanes↗
Separation of gallic acid from Cornus officinalis Sieb. et Zucc by high-speed counter-current chromatography.
Gallic acid was separated from a n-butanol extract of the fruit of Cornus officinalis Sieb. et Zucc by high-speed countercurrent chromatography in two steps using two solvent systems composed of ethyl-acetate-ethanol n-butanol-water (5:1.8:6, v/v/v) and ethyl acetate-ethanol-water (5:0.5:6, v/v/v) successively. From 1 g of n-butanol extract the method produced 60 mg of gallic acid at a purity of 97%.
Chromatography, High Pressure Liquid↗