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Biomedical subjects

Yu Liu

Publications and source records attributed to Yu Liu.

At least 181 records · Page 10Linked to original sources
PubMed2004

Thermodynamics of the molecular and chiral recognition of cycloalkanols and camphor by modified beta-cyclodextrins possessing simple aromatic tethers.

The complex stability constants (K(S)) and thermodynamic parameters (DeltaG degrees, DeltaH degrees, and TDeltaS degrees ) for 1:1 inclusion complexation of beta-cyclodextrin (beta-CD) derivatives, 6-O-phenyl-beta-CD (2) 6-O-(4-formyl-phenyl)-beta-CD (3), 6-O-(4-nitrophenyl)-beta-CD (4), 6-O-(4-bromophenyl)-beta-CD (5), 6-O-(4-chlorophenyl)]-beta-CD (6), and 6-O-(4-hydroxybenzoyl)-beta-CD (7) with representative guest molecules, cyclic alcohols (cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol), (+/-)-borneol, and (+/-)-camphor, have been determined by means of titration microcalorimetry in an aqueous phosphate buffer solution (pH = 7.20) at 298.15 K. The results obtained indicate that the introduction to beta-CD of an aromatic ring bearing different substituent groups significantly enhances the molecular binding ability and moderately alters the chiral discrimination ability for the guests examined here, displaying the highest enantioselectivity of up to 4.01 for the inclusion complexation of 6 with (+/-)-camphor. The enhanced molecular/chiral discrimination ability caused by derivatization is attributed solely to increased positive entropy changes due to the expanding hydrophobic interaction and desolvation effects. The binding modes of host-guest interactions derived from ROESY spectroscopy data show that the resulting complex of 4 and (+)-borneol possesses better induced-fit interaction as compared to (-)-borneol, which is responsible for the enhanced molecular/chiral recognition ability.

Alcohols↗
PubMed2004

Effects of positive allosteric modulators of the GABAB receptor on cocaine self-administration in rats.

RATIONALE: Previous studies have strongly implicated a role for GABA(B) receptors in modulating the reinforcing effects of cocaine. OBJECTIVE: The purpose of the present study was to examine the efficacy of two novel positive allosteric modulators of the GABA(B) receptor, CGP7930 and GS39783, to decrease cocaine self-administration in rats responding under various schedules of reinforcement. METHODS: Rats were trained to self-administer cocaine under progressive ratio (PR), fixed ratio (FR) and discrete trials (DT) schedules of reinforcement, and the ability of CGP7930 and GS39783 to decrease cocaine-maintained responding was examined. RESULTS: On a PR schedule, CGP7930 markedly decreased break points maintained by 1.5 mg/kg per injection cocaine in a dose-dependent manner. GS39783 produced only modest decreases in cocaine-reinforced break points, with only the highest dose decreasing break points relative to baseline. On an FR1 schedule of reinforcement, both drugs decreased responding for a threshold dose of cocaine, but did not alter responding for higher doses of cocaine. In a DT procedure, 1.5 mg/kg per injection cocaine was made available during three 10-min trials each hour during 24-h sessions (DT3), engendering a circadian pattern of responding characterized by high numbers of infusions during the dark phase and low numbers of infusions during the light phase. Doses of 30 mg/kg CGP7930, 3.0 mg/kg GS39783 and 2.5 mg/kg baclofen significantly decreased cocaine-maintained responding when administered at the beginning of the dark phase of the cycle. Across all schedules, CGP7930 was more effective at decreasing cocaine self-administration than GS39783, a finding that may be due to differences in bioavailability between the two drugs. CONCLUSIONS: These findings suggest that positive allosteric modulators of the GABA(B) receptor may hold promise as potential pharmacotherapies for cocaine abuse and dependence.

Analysis of Variance↗
PubMed2004

Diastereoisomer-selective inclusion complexation of Cinchona alkaloids with a modified beta-cyclodextrin: fluorescent behavior enhanced by chiral-tether binding. Short communication.

The molecular 1:1 complexation of cinchona alkaloids by mono(6-deoxy-6-{[(R)-1-(hydroxymethyl)propyl]amino})-beta-cyclodextrin (1) in aqueous solution has been investigated by 2D-NMR, fluorescence titration, and fluorescence-lifetime experiments. Generally, with 1 as the host, in contrast to beta-cyclodextrin proper, strong binding of quinine (2; Ka = 84,200 M(-1)) and quinidine (3; Ka = 27,300 M(-1)) at pH 6.8 was observed, as monitored by an increase in fluorescence intensity, with a fair degree of diastereoisomer discrimination (ca. 3:1). To rationalize these results, two possible cooperative complexation modes, including specific H-bonding interactions to the chiral tether of the cyclodextrin portion, are proposed.

Binding Sites↗
PubMed2004

Respirometric activities of heterotrophic and nitrifying populations in aerobic granules developed at different substrate N/COD ratios.

Aerobic granules were successfully developed at substrate N/COD ratios ranging from 5/100 to 30/100 by weight. By measuring respective respirometric activities of heterotrophic, ammonia-oxidizing, and nitrite-oxidizing bacteria, it was found that the relative abundance of nitrifying bacteria over heterotrophs in aerobic granules was closely related to the substrate N/COD ratios. Results further showed that the populations of both ammonia and nitrite oxidizers were significantly enriched with the increase of the substrate N/COD ratio, while a decreasing trend of heterotrophic population was observed in the aerobic granules. These seem to indicate that high substrate N/COD ratio favors the selection of nitrifying bacteria in the aerobic granules, while the relative activity of nitrifying population against heterotrophic population evolved until a balance between two populations was reached in the aerobic granular sludge community. Moreover, cell elemental composition was correlated with the shift in microbial populations, e.g., the enriched nitrifying population in the aerobic granules resulted in a high cell nitrogen content normalized to cell carbon content. This study provides a good insight into microbial interaction in aerobic granules.

Aerobiosis↗
PubMed2004

State of the art of biogranulation technology for wastewater treatment.

Biogranulation technology developed for wastewater treatment includes anaerobic and aerobic granulation processes. Anaerobic granulation is relatively well known, but research on aerobic granulation commenced only recently. Many full-scale anaerobic granular sludge units have been operated worldwide, but no report exists of similar units for aerobic granulation. This paper reviews the fundamentals and applications of biogranulation technology in wastewater treatment. Aspects discussed include the models of biogranulation, major factors influencing biogranulation, characteristics of biogranules, and their industrial applications. This review hopes to provide a platform for developing novel granules-based bioreactors and devising a unified interpretation of the formation of anaerobic and aerobic granules under various operation conditions.

Aerobiosis↗
PubMed2004

Identification of the mouse H-ficolin gene as a pseudogene and orthology between mouse ficolins A/B and human L-/M-ficolins.

Ficolin is a collagenous lectin which plays a crucial role in innate immunity. Three and two ficolins have been identified in human and mice, respectively. To identify the mouse homologue of human H-ficolin and to elucidate the orthology between mouse ficolins A/B and human L-/M-ficolins, the gene structures were explored. The mouse homologue of the H-ficolin gene was identified as a pseudogene on chromosome 4. The mouse ficolin A gene was located far from the ficolin B gene on chromosome 2, whereas the human L-ficolin and M-ficolin genes were close in the region homologous to the ficolin B locus. Together with the exon-intron structures and the phylogenetic tree, these results suggest that ficolin B is the mouse orthologue of M-ficolin and that the genes encoding serum-type ficolins, ficolin A and L-ficolin, were generated independently from the ficolin B/M-ficolin lineage each in mice and primates.

Amino Acid Sequence↗
PubMed2004

Characterization of rtSH3p13 gene encoding a development protein involved in vesicular traffic in spermiogenesis.

A cDNA, designated as rtSH3p13, was isolated from a rat testis cDNA library. It consists of 1463 bp nuclear acids, which encodes a protein of 312 amino acids and was assigned the GenBank accession number AF227439. The deduced rtSH3p13 protein is a truncated isoform of SH3p13 as a result of mRNA alternative splicing. It is mainly expressed in the rat testis, detected in spermatids at the steps 8-19 of spermiogenesis, and found around the acrosome. During postnatal development, rtSH3p13 appears on day 18 and reaches maximum on day 60. Further experimental results suggested that rtSH3p13 forms a complex with activated epidermal growth factor receptor (EGFR) and interacts with synaptojanin I. Surprisingly, similar to SH3 domain, the V region of rtSH3p13 also inhibits endocytosis in CHO cells. Our results reveal a link between an rtSH3p13-synaptojanin-clathrin complex-mediated formation of pits and the process of spermiogenesis.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Peroxisome proliferator-activated receptor-gamma ligands ameliorate experimental autoimmune myocarditis associated with inhibition of self-sensitive T cells.

OBJECTIVE: Recent evidence has suggested that peroxisome proliferator-activated receptor-gamma (PPAR-gamma) serves as a negative regulator in the immune system. In the present study, we investigated the expression of PPAR-gamma and the effect of PPAR-gamma ligands on experimental autoimmune myocarditis (EAM). METHODS AND RESULTS: Experimental autoimmune myocarditis was induced in Lewis rats by immunization with porcine cardiac myosin. PPAR-gamma ligands 15-deoxy-Delta-PGJ2 200 microg x kg(-1) x d(-1) by ip and pioglitazone 10 mg x kg(-1) x d(-1) by oral were administered for 3 weeks. PPAR-gamma expression was upregulated in myocarditis and the enhanced PPAR-gamma expression was prominently stained in the nuclear and perinuclear regions of the positive-stained cells in the inflammatory lesions. Administration of PPAR-gamma ligands markedly reduced the severity of myocarditis, as indicated by the heart weight/body weight ratio, pericardial effusion scores, macroscopic scores, and microscopic scores. The upregulated PPAR-gamma expression was also reduced by PPAR-gamma ligands treatment. In addition, PPAR-gamma ligands suppressed the proliferative response and interferon-gamma production of T cell-enriched splenocytes from rats with EAM. Furthermore, the cytotoxic activity and myocarditogenic potential of these T cells were inhibited by PPAR-gamma ligands treatment. CONCLUSIONS: PPAR-gamma ligands ameliorate EAM associated with inhibition of expansion and activation of the self-sensitive T cells. These results suggest that PPAR-gamma ligands may have the potential to modulate human inflammatory heart diseases as myocarditis.

Animals↗
PubMed2004

Nitric oxide modulates microglial activation.

BACKGROUND: Nitric oxide (NO) has important physiological regulatory roles, i.e, vasodilation, neurotransmitter release, etc. Little is known about the processes in neural tissues, which stabilize microglia. This study attempts to answer this question by demonstrating a role for basal NO in maintaining microglia juxtaposed to neurons. MATERIAL/METHODS: Mytilus edulis (a marine bivalve), were used to examine microglia egress from excised pedal ganglia microscopically. Nitric oxide is measured in excised pedal ganglia amperometrically in real-time. RESULTS: Pedal ganglia exhibit basal NO release (1 nM range). Inhibition of basal NO release by L-NAME results in greater numbers of microglia in the incubation medium. This process appears to involve two phases of egress. The first involves a slow egress of microglia, whereas the second, occurring 18 hours later, involves a more rapid release of these cells. Low levels of the NO donor SNAP (1 nM) does not interrupt microglial egress, whereas in the presence of L-NAME it does. Exposing the ganglia to high NO levels for a short period of time inhibits their egress. CONCLUSIONS: Spontaneous ganglionic NO release maintains/stabilizes microglia juxtaposed to neurons. Excised ganglia at the various observation periods reveals a transition of constitutive nitric oxide synthase (NOS) to inducible NOS derived NO. It also appears that the microglia in some unknown manner become insensitive to iNOS derived NO since they exhibit enhanced migration during this last phase of the ganglionic NO response. Taken together, NO is involved with regulating microglial activation.

Animals↗
PubMed2004

[Effects of hypertriglyceridemia on platelet activities in endogenous hypertriglyceridemic patients].

OBJECTIVE: To explore the effects of hypertriglyceridemia on platelet activities. METHODS: The plasma prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (Fg), blood platelet count (BPC) and platelet alpha granule membrane protein-140 (GMP-140) levels in endogenous hypertriglyceridemic patients were determined, and the relationship between platelet activities and fasting plasma lipids was assessed. RESULTS: It was found that PT, Fg levels, BPC and plasma GMP-140 concentration showed no statistically significant difference between the control and hypertriglyceridemic subjects (P > 0.05). PT was correlated with the levels of plasma BG and apo E (r = 0.500, P = 0.012), the levels of Fg was positively correlated with BG (r = 0.598, P = 0.000), and BPC of HTG subjects was negatively correlated with TG (r = -0.489, P < 0.05). GMP-140 content was positively correlated with the levels of plasma TC and LDL-C (r = 0.647, 0.833, P < 0.01); in HTG patients it was inversely correlated with age and PT (r = -0.480, -0.490, P < 0.05). CONCLUSION: All of these indicated that increasing of coagulation activity in hypertriglyceridemic patients was correlated with dysfunction of plasma lipids and change of apolipoproteins levels. Plasma GMP-140 was not obviously correlated with plasma TG content, but was positively correlated with plasma TC and LDL-C contents.

Aged↗
PubMed2004

[The interrelationships between serum triglyceride, total cholesterol and HDL subpopulations].

OBJECTIVE: To assess the influence of serum triglyceride (TG) level and total cholesterol (TC) level on the change of the contents of serum HDL subpopulations. METHODS: The apolipoprotein (apo) A-I contents of serum HDL subpopulations in 289 subjects were determined by two-dimensional gel electrophoresis associated with immunodetection method. RESULTS: Analysis of the data on the serum TG levels in subjects revealed that the apoA-I contents of pre beta 1-HDL, pre beta 2-HDL, HDL3b and HDL3a increased with the increase of TG level, whereas the apoA-I contents of HDL2a and HDL2b decreased. By comparison with the data of normal TG group, the apoA-I contents of pre beta 1-HDL and HDL3b in the high TG and very high TG groups were significantly higher, whereas those of HDL2b were significantly lower in the high TG and very high TG groups. Analysis of the data on the serum TC levels in subjects revealed that the apoA-I contents of pre beta 1-HDL, pre beta 2-HDL, HDL2c and HDL3b increased with the increase of TC level, while the apoA-I contents of HDL2b decreased. As compared with the data of TC desirable group, the apoA-I contents of pre beta 1-HDL, HDL3c and HDL3b were significantly higher in the high TC group. CONCLUSION: With the increase of serum TG or TC, there is a general shift toward small-sized HDL in subjects. Besides, the change of serum TG level is a more important factor influencing the components of HDL subpopulations, compared with the change of serum TC level.

Apolipoprotein A-I↗
PubMed2004

[Inhibitory effect of quercetin, rutin and puerarin on HDL oxidation induced by Cu2+].

OBJECTIVE: To evaluate the inhibitory effect of quercetin, rutin and puerarin on the HDL oxidation induced by Cu2+ and to investigate their action on the prevention and cure of atherosclerosis. METHODS: The serum HDL of healthy human was isolated by the one step density gradient ultracentrifugation. The HDL oxidation was induced by Cu2+ in vitro for different time, quercetin and rutin at 5 micromol/L were added ahead, respectively. HDL was oxidized, then identified by A234, REM, TBARS and protein carbonyls content, and was compared with control group. Inhibition of puerarin was weak. RESULTS: (1) A234, REM, TBARS and protein carbonyls formation increased gradually during HDL oxidation induced by Cu2+ in vitro. (2) During HDL oxidation induced by Cu2+ in vitro and incubation with quercetin and rutin, the kinetic changes of A234, REM, TBARS and protein carbonyls formation showed lag phases of 2 h, 2-4 h, 2-4 h and 4 h respectively, and showed reductions by 24.2%-49.0% (P<0.001) and 9.4%-42.0% (P<0.01); 3.0%-25.0% and 4.0%-20.7% (P<0.05); 7.9%-34.1% and 1.2%-26.8% (P<0.05); 28.3%-50.4% and 18.6%-64.6% (P<0.001) respectively. In the puerarin group, only protein carbonyls formation showed a lag phase of 4 h and a reduction by 14.1%-52.1% (P<0.001) while its A234, REM, TBARS reduced to a small extent. CONCLUSION: The above findings suggested that quercetin and rutin inhibit oxidation of HDL significantly, but puerarin has less antioxidative function.

Antioxidants↗
PubMed2003

[Peroxisome proliferation-activated receptor-gamma ligands ameliorate autoimmune myocarditis associated with inhibition of T cell immunity].

OBJECTIVE: To investigate the role of peroxisome proliferator-activated receptor-gamma (PPAR gamma) on autoimmune myocarditis, and to test the hypothesis that PPAR-gamma ligands reduce experimental autoimmune myocarditis (EAM) associated with inhibition of the expansion and activation of self-sensitive T cells. METHODS: EAM was induced in Lewis rats by immunization with porcine cardiac myosin. Then the rats were divided into 3 groups of 9 rats: PPAR-gamma ligand 15-deoxy-(12,14)-PGJ(2) (15d-PGJ(2)) group (15d-PGJ(2) was injected intraperitoneally at the dosage of 200 microg.kg(-1).d(-1)), pioglitazone (PIO) group (PIO was mixed with the food and than fed at the dosage of 10 mg.kg(-1).d(-1)), and positive control group (phosphate-buffered saline was injected intraperitoneally). Nine normal rats were used as normal controls. Three weeks later, the rats underwent thoracotomy to undergo pathologic examination. The numbers of CD4(+) cells, CD8(+) cells, and macrophages were calculated by microscopy. Immunohistochemistry was used to examine the location and expression of PPAR gamma. Western blotting was used to examine the relative amount of PPAR gamma protein. The proliferative response and the cytotoxicity of T cell-enriched splenocytes and lymph node cells were determined. Another rats were killed 12 days after immunization. Their spleens and lymph nodes were taken out. T-cell rich splenocytes and cells from the lymph nodes were cultured. Cardiac myosin and 15d-PGJ(2) were added. [(3)H] thymine was added 72 hours after. ELISA was used to examine the interferon-gamma (IFN-gamma) in the supernatant. 15d-PGJ(2), PIO, or PBS were given to immunize the rats. The rats were killed 12 days after. The lymph nodes were taken out to make single cell suspension. (51)Cr was used to label the cells so as to calculate the %cytotoxicity. RESULTS: All immunized rats showed myocarditis. The numbers of CD4(+) cells, CD8(+) T cells, and macrophages, were 18 +/- 5, 7 +/- 2, and 45 +/- 8/six 0.25 mm x 0.25 mm squares. PPAR gamma was mainly located in the nuclear and perinuclear regions of infiltrating inflammatory cells, such as mononuclear cells and macrophage-like cells. The expression of PPAR gamma in the myocardium of EAM rats was 3.7 times higher than of the normal rats. The heart weight/body weight ratio, pericardial effusion scores, macroscopic scores and microscopic scores of the 15d-PGJ group were significantly lower than those of the positive control group. The numbers of CD4(+) cells of the 15d-PGJ and PIO groups were 8 +/- 2 and 10 +/- 3, both significantly lower than that of the positive control group (both P < 0.01), the numbers of CD8(+) cells of the 15d-PGJ and PIO groups were 3 +/- 1 and 4 +/- 2 respectively, both significantly lower than that of the positive control group (P < 0.01 and P < 0.05), and the numbers of macrophages of the 15d-PGJ and PIO groups were 22 +/- 4 and 26 +/- 6 respectively, both significantly lower than that of the positive control group (both P < 0.01). The myocardiogenicity and the severity of myocarditis of the 15d-PGJ(2)- and PIO-groups were at lower degrees compared with those of the positive control group. The % cytotoxic activity was 10.2% +/- 2.6% in the 15d-PGJ(2) group and was 11.6% +/- 3.7% in the PIO group, both significantly lower than that of the positive control group (37.7% +/- 8.4%, both P < 0.01) Stimulated by cardiac myosin, the T-cell rich splenocytes and cells from lymph nodes showed obvious proliferation and production of IFN-gamma. The cardiac myosin-stimulated cell proliferation and production of IFN-gamma in the 15d-PGJ(2) and PIO groups were significantly reduced in comparison with those in the positive control group. CONCLUSION: PPAR-gamma ligands ameliorate EAM associated with inhibition of expansion and activation of the self-sensitive T cells.

Animals↗
PubMed2003

A novel granular sludge sequencing batch reactor for removal of organic and nitrogen from wastewater.

Microbial granules were developed at different substrate N/COD ratios in sequencing batch reactors (SBR). Results showed that heterotrophic, nitrifying, and denitrifying populations could peacefully co-exist in microbial granules, while increased substrate N/COD ratio led to significant shifts among three populations in granules. Enhanced activities of nitrifying and denitrifying populations were obtained in microbial granules developed at high substrate N/COD ratios, however, heterotrophic populations in granules tended to decrease with the increase of substrate N/COD ratio. It was found that dissolved oxygen (DO) concentration had a pronounced effect on the efficiency of denitrification by microbial granules, meanwhile the results also indicated that a certain mixing power would be provided to ensure mass transfer between liquid and granules during denitrification. It was demonstrated that complete organics and nitrogen removal can be achieved in single granule-based SBR with high efficiency and stable performance. This is the first study to show the capability of microbial granules in simultaneous removal of organic carbon and nitrogen from wastewater.

Bacteria, Aerobic↗