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Biomedical subjects

J Wang

Publications and source records attributed to J Wang.

At least 325 records · Page 18Linked to original sources
PubMed2002

Treatment of antibiotics wastewater utilizing successive hydrolysis, denitrification and nitrification.

A process consisting of anaerobic hydrolysis, denitrification, and oxidation/nitrification was proposed for simultaneous removal of carbon and nitrogen from terramycin crystallizing mother solution (TCMS), and its performance was investigated by treating diluted TCMS in a lab-scale continuous flow column system. Direct denitrification-nitrification of diluted TCMS produced a significant residual of nitrate and nitrite, which disappeared 44 days after startup of anaerobic hydrolysis column. The electron donors available to denitrification were increased by 6 times after diluted TCMS was treated in the hydrolysis column under an HRT of 2.5 h or longer. The reaction rates of organics decomposition, nitrification, and denitrification were also significantly increased due to reduction of terramycin and decomposition of complicated molecules to small molecules during anaerobic hydrolysis. The specific denitrification rate and nitrification rate increased from 0.033 d(-1) and 0.01 d(-1) to 0.045 d(-1) and 0.021 d(-1) respectively after diluted TCMS (dilution ratio: 1:4) was hydrolyzed in anaerobic hydrolysis column at a hydraulic retention time (HRT) of 4 h.

Anti-Bacterial Agents↗
PubMed2002

Adherence to statin treatment and readmission of patients after myocardial infarction: a six year follow up study.

OBJECTIVE: To investigate patients' adherence to statin treatment prescribed following their first myocardial infarction (MI) and to estimate the effect of adherence to statins on recurrence of MI and all cause mortality. DESIGN: Cohort study using a record linkage database. SETTING: Tayside, Scotland, UK. PATIENTS: Patients who experienced their first MI between January 1990 and November 1995. MAIN OUTCOME MEASURES: Percentage of statin use and adherence to statins by patients after an MI and the relative risk of hospitalisation for recurrent MI. The effect of adherence on all cause mortality was also examined. The covariates used were age, sex, socioeconomic deprivation, serum cholesterol concentration, diabetes mellitus, cardiovascular drug use, and other hospitalisations. RESULTS: Of 5590 patients who experienced an incident MI, 717 (12.8%) experienced at least one further MI. Only 7.7% of patients used statins after an MI during the study period. Compared with those not taking statins, those who had 80% or better adherence to statin treatment had an adjusted relative risk of recurrent MI of 0.19 (95% confidence interval (CI) 0.08 to 0.47) and all cause mortality of 0.47 (95% CI 0.22 to 0.99). There was no significant reduction in either end point for those who were less than 80% adherent to statins. CONCLUSIONS: Despite the infrequent use of statin during the study period, good adherence to statin treatment was associated with lower risk of recurrent MI.

Adult↗
PubMed2002

Differential dimerization and association among resistin family proteins with implications for functional specificity.

Secreted by white adipose tissue as a hormone, resistin was identified as a possible link between obesity and insulin resistance. High circulating resistin levels were observed to correlate with obesity. Administration of resistin lowered the glucose tolerance threshold and impaired insulin activity; whereas anti-resistin antibodies had the opposite effects. However, contradictory data were subsequently reported in regard to the correlation between resistin expression level and obesity or type 2 diabetes. Two additional proteins that share a highly homologous C-terminus with resistin have been identified in mouse, and one in human, forming a resistin-related protein family. Resistin was shown to dimerize through a disulfide bond formed by the N-terminal-most cysteine (Cys26). Here we demonstrate that while Cys26 is both necessary and sufficient for homodimer formation, all three resistin family members can also interact with one another regardless of the presence of Cys26 through non-covalent interactions. Furthermore, protein crosslinking analysis indicated that resistin and resistin beta, but not resistin alpha, exist as multimers, probably with a dimer as the subunit. The multiple protein complex formation is obviously at a level higher than the Cys26 disulfide bonding. These results suggest the potential importance of considering intermolecular interactions among resistin family members in studying their functions.

Animals↗
PubMed2002

Diver with acute abdominal pain, right leg paresthesias and weakness: a case report.

A 29-year-old man was brought to an emergency department by the United States Coast Guard with chief complaints of severe abdominal pain, right leg paresthesia and weakness following four deep air dives. Physical examination before recompression treatment was remarkable for diffuse abdominal tenderness and right leg weakness. The patient was diagnosed in the emergency room with type II decompression sickness (DCS) and underwent standard recompression therapy. He experienced complete resolution of weakness after hyperbaric oxygen (HBO) therapy, but his abdominal pain was persistent. Further investigation led to the diagnosis of acute appendicitis with perforation. The patient underwent appendectomy and intravenous antibiotic therapy and was discharged to his home on hospital day five without complications. This case reinforces the importance of careful clinical assessment of divers and illustrates the potentially wide differential diagnosis of DCS. This is the first reported case of recompression treatment of a diver with acute appendicitis and type II DCS.

Abdominal Pain↗
PubMed2001

Modeling of inducer exclusion and catabolite repression based on a PTS-dependent sucrose and non-PTS-dependent glycerol transport systems in Escherichia coli K-12 and its experimental verification.

We used genetically engineered sucrose positive Escherichia coli K-12 derivatives as a model system for the modeling and experimental verification of regulatory processes in bacteria. These cells take up and metabolize sucrose by the phosphoenolpyruvate (PEP)-dependent sucrose phosphotransferase system (Scr-PTS). Expression of the scr genes, which cluster in two different operons (scrYAB and scrK), is negatively controlled by the ScrR repressor. Additionally, expression of the scrYAB operon, but not of the scrK operon is positively controlled by the cAMP-CRP complex. Modeling of sucrose transport and metabolism through the Scr-system and of the scr gene expression has been performed using a modular and object-orientated new approach. To verify the model and identify important model parameters we measured in a first set of experiments induction kinetics of the scr genes after growth on glycerol using strains with single copy lacZ operon fusions in the scrK or scrY genes, respectively. In a second set of experiments an additional copy of the complete scr-regulon was integrated into the chromosome to construct diplogenotic strains. Differences were observed in the induction kinetics of the cAMP-CRP-dependent scrY operon compared to the cAMP-CRP independent scrK operon as well as between the single copy and the corresponding diplogenotic strains.

Biological Transport, Active↗
PubMed2001

Structures of Aquifex aeolicus KDO8P synthase in complex with R5P and PEP, and with a bisubstrate inhibitor: role of active site water in catalysis.

We have determined the crystal structures of the metalloenzyme 3-deoxy-D-manno-octulosonate 8-phosphate (KDO8P) synthase from Aquifex aeolicus in complex with phosphoenolpyruvate (PEP) and ribose 5-phosphate (R5P), and with a bisubstrate inhibitor that mimics the postulated linear reaction intermediate. R5P, which is not a substrate for KDO8P synthase, binds in a manner similar to that of arabinose 5-phosphate (A5P), which is the natural substrate. The lack of reactivity of R5P appears to be primarily a consequence of the loss of a water molecule coordinated to Cd(2+) and located on the si side of PEP. This water molecule is no longer present because it cannot form a hydrogen bond with C2-OH(R5P), which is oriented in a different direction from C2-OH(A5P). The bisubstrate inhibitor binds with its phosphate and phosphonate moieties occupying the positions of the phosphate groups of A5P and PEP, respectively. One of the inhibitor hydroxyls replaces water as a ligand of Cd(2+). The current work supports a mechanism for the synthesis of KDO8P, in which a hydroxide ion on the si side of PEP attacks C2(PEP), forming a tetrahedral-like intermediate with a buildup of negative charge at C3(PEP). The ensuing condensation of C3(PEP) with C1(A5P) would be favored by a proton transfer from the phosphate moiety of PEP to the aldehyde carbonyl of A5P to generate the hydroxyl. Overall, the process can be described as a syn addition of water and A5P to the si side of PEP.

Aldehyde-Lyases↗
PubMed2001

[Expression and activity of cyclooxygenases-1 and -2 in acetic acid induced gastric ulcer in rats].

OBJECTIVE: To investigate the dynamic changes of the expression and activity of the two forms of cyclooxygenase (COX-1 and COX-2) in animal model of gastric ulcer and their role in the pathological process of gastric ulcer. METHODS: Acetic acid was perfused into the gastric cavitties of 130 rats to produce animal model of /gastric ulcer. Specimens of the base part and margin of gastric ulcer and normal gastric tissue around were collected 1 hour to 15 days after the induction. RT-PCR and Western blotting were used to detect the expression of COX-1 mRNA and COX-2 mRNA and their protein levels. The total COX activity was determined by determining the ability of tissue homogenate to metabolize arachidonic acid to produce PGE2. RESULTS: After the ulcer induction, the expression of COX-2 mRNA and its protein were highly induced at the ulcer base in inflammation stage (6 hours to 3 days) and kept at a high level during the healing stage (3 days to 15 days), while the expression of COX-1 remained relatively stable. The homogenates from tissues of basal and marginal parts of ulcer showed very high level of COX activity during the ulcer healing stage. The COX activity of normal tissue around ulcer showed little change before and after ulcer induction. CONCLUSION: COX, especially COX-2, which maintains a high level of expression and activity during the ulcer healing stage, may play an important role in ulcer healing and tissue remodeling.

Acetic Acid↗
PubMed2001

RNase H mediated cleavage of RNA by cyclohexene nucleic acid (CeNA).

Cyclohexene nucleic acid (CeNA) forms a duplex with RNA that is more stable than a DNA-RNA duplex (DeltaTm per modification: +2 degrees C). A cyclohexenyl A nucleotide adopts a 3'-endo conformation when introduced in dsDNA. The neighbouring deoxynucleotide adopts an O4'-endo conformation. The CeNA:RNA duplex is cleaved by RNase H. The Vmax and Km of the cleavage reaction for CeNA:RNA and DNA:RNA is in the same range, although the kcat value is about 600 times lower in the case of CeNA:RNA.

Cyclohexanes↗
PubMed2001

A straightforward stereoselective synthesis of D- and L-5-hydroxy-4-hydroxymethyl-2-cyclohexenylguanine.

A novel and facile synthesis of 5-hydroxy-4-hydroxymethyl-2-cyclohexenylguanine 1 is described. The key steps involve a Diels-Alder reaction of ethyl (2E)-3-acetyloxy-2-propenoate 2 as dienophile with Danishefsky's diene 3 to build up the six-membered ring skeleton, a Fraser-Reid reductive rearrangement of the adduct using LiAlH(4), and base-moiety introduction using a Mitsunobu reaction. Optically pure D- and L-1 were obtained via resolution of intermediate 7 with (R)-(-)-methylmandelic acid. The synthetic procedure toward racemic 1 consists of only five steps and has proven to be highly efficient toward the synthesis of cyclohexenyl nucleosides.

Aluminum Compounds↗
PubMed2001

[Dynamic change of tumor necrosis factor and endothelin during perioperative period in patients undergoing coronary artery bypass grafting].

OBJECTIVE: To observe the dynamic changes of tumor necrosis factor-alpha(TNF-alpha) and endothelin (ET-1) during perioperative period in patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) and to investigate their pathological significance so as to bring up feasible measure to increase therapeutic effect. METHODS: Blood samples of 32 patients undergoing CABG with CPB were drawn before operation, induction period of anaesthesia, after aortic crossclamping and declamping, by the end of surgery, and 2 hours, 8 hours, and 24 hours after surgery. The plasma TNF-alpha and ET-1 were measured by radioimmunoassay (RIA). RESULTS: (1) The plasma TNF-alpha level increased markedly after aortic crossclamping (18.3 ng/L +/- 3.4 ng/L vs 12.1 ng/L +/- 2.0 ng/L, P < 0.05) and went up to the peak value(22.4 ng/L +/- 3.6 ng/L) after aortic declamping, and then decreased. However, till 24 hours after operation, the TNF-alpha concentration maintained at a level higher than that before surgery (18.5 ng/L +/- 4.1 ng/L vs 12.1 ng/L +/- 2.0 ng/L, P < 0.05. After aortic declamping, during reperfusion of the lungs the TNF-alpha level was significantly higher than that after aortic crossclamping and before declamping (22.4 ng/L +/- 3.6 ng/L vs 18.3 ng/L +/- 3.4 ng/L P < 0.05). (2) The plasma ET-1 increased significantly after aortic crossclamping (146 ng/L +/- 20 ng/L vs 97 ng/L +/- 14 ng/L, P < 0.05) and went down after aortic declamping. Two hours after surgery, the plasma ET-1 increased again and reached the second height (134 ng/L +/- 19 ng/L), and then went down again and decreased to 92 ng/L +/- 18 ng/L 24 h after operation. CONCLUSION: (1) Attenuation of inflammatory reactions mediated by TNF-alpha should be considered an important strategy for myocardial and lung protection. (2) During the perioperative period of CABG the plasma ET-1 level shows two peaks, occurring respectively after aortic crossclamping and 2 h after surgery, which may result from operation itself and ischemia-reperfusion injury.

Adult↗
PubMed2001

Simultaneous determination of artificial sweeteners, preservatives, caffeine, theobromine and theophylline in food and pharmaceutical preparations by ion chromatography.

A novel ion chromatographic method was proposed for the simultaneous determination of artificial sweeteners (sodium saccharin, aspartame, acesulfame-K), preservatives (benzoic acid, sorbic acid), caffeine, theobromine and theophylline. The separation was performed on an anion-exchange analytical column operated at 40 degrees C within 45 min by an isocratic elution with 5 mM aqueous NaH2PO4 (pH 8.20) solution containing 4% (v/v) acetonitrile as eluent, and the determination by wavelength-switching ultraviolet absorbance detection. The detection limits (signal-to-noise ratio 3:1) for all analytes were below the sub-microg/ml level. Under the experimental conditions, several organic acids, including citric acid, malic acid, tartaric acid and ascorbic acid, did not interfere with the determination. The method has been successfully applied to the analysis of various food and pharmaceutical preparations, and the average recoveries for real samples ranged from 85 to 104%. The levels of all analytes determined by this method were in good agreement with those obtained by the high-performance liquid chromatographic procedure. The results also indicated that ion chromatography would be possibly a beneficial alternative to conventional high-performance liquid chromatography for the separation and determination of these compounds.

Caffeine↗
PubMed2001

Effects of whey protein and resistance exercise on body cell mass, muscle strength, and quality of life in women with HIV.

OBJECTIVE: To determine the effects of whey protein, resistance exercise, and combined protein and exercise treatment on body cell mass (BCM), muscle strength, and quality of life (QOL) in HIV-infected women with reduced BCM. DESIGN AND SETTING: Prospective, randomized, controlled trial at a university hospital in New York City. METHODS: A volunteer sample of 30 HIV-infected women were randomized to whey protein (PRO), progressive resistance exercise (PRE), or combined treatment (PRO-PRE) for 14 weeks after a 6-week control period. The main outcome measures were body weight, BCM, skeletal muscle, fat mass, muscle strength, and QOL. RESULTS: There were no significant changes in BCM, strength, or QOL during the control period. PRO patients gained 3.6 kg (P = 0.001), and 2.5 kg fat (P = 0.002) with no change in BCM (0.5 kg; P = 0.07) or skeletal muscle (0.6 kg; P = 0.12). The PRE group increased BCM (0.74 kg;P = 0.03) and skeletal muscle (1.2 kg; P < 0.001) and decreased fat (1.7 kg; P = 0.02). PRO-PRE increased BCM (0.61 kg; P = 0.01) without change in skeletal muscle (0.6 kg; P = 0.30). Strength increased for both exercise groups (range, 40.6-95.3%; P < 0.001). The QOL physical activity score improved for PRE (P = 0.02) and worsened for PRO (P = 0.01). CONCLUSIONS: Resistance exercise significantly increased BCM, muscle mass, muscle strength, and QOL in HIV-infected women with reduced BCM. Whey protein had little effect on BCM accrual. Combined protein and exercise did not increase BCM in excess of gains achieved by exercise alone.

Adult↗
PubMed2001

beta-adrenergic receptor blockers restore cardiac calcium release channel (ryanodine receptor) structure and function in heart failure.

BACKGROUND: beta-Adrenergic receptor blockade is one of the most effective treatments for heart failure, a leading cause of mortality worldwide. The use of beta-adrenergic receptor blockers in patients with heart failure is counterintuitive, however, because they are known to decrease contractility in normal hearts. The ryanodine receptor (RyR2) on cardiac sarcoplasmic reticulum is the key calcium release channel required for excitation-contraction coupling. In failing hearts, the stoichiometry and function of the RyR2 macromolecular complex is altered. Decreased levels of phosphatases (PP1 and PP2A) and hyperphosphorylation by protein kinase A result in dissociation of the regulatory protein FKBP12.6 and channels with increased open probability. METHODS AND RESULTS: Here, we show that systemic oral administration of a beta-adrenergic receptor blocker reverses protein kinase A hyperphosphorylation of RyR2, restores the stoichiometry of the RyR2 macromolecular complex, and normalizes single-channel function in a canine model of heart failure. CONCLUSIONS: These results may, in part, explain the improved cardiac function observed in heart failure patients treated with beta-adrenergic receptor blockers.

Adrenergic beta-Antagonists↗
PubMed2001

A kinetic study on the pairwise competition reaction of alpha-diazo esters with rhodium(II) catalysts: implication for the mechanism of Rh(II)-carbene transfer.

The relative rate constants for the Rh(II)-mediated diazo decomposition of a series of para- or meta-substituted diazophenylacetates were measured through intermolecular competition. The kinetic data were further subjected to Hammett correlation analysis and were found to have better linear correlation with sigma(+). Reaction constants for four Rh(II) catalysts have been obtained, Rh(2)(OAc)(4) (rho = -1.29 with sigma(+), r = -0.99), Rh(2)(Ooct)(4) (rho = -1.31 with sigma(+), r = -0.99), Rh(2)(acam)(4) (rho = -1.18 with sigma(+), r = -0.99), Rh(2)(O(2)CCF(3))(4) (rho = -1.46 with sigma(+), r = -0.99). The mechanistic implications of these data are discussed.

Journal Article↗
PubMed2001

Phospholipid metabolite 1-palmitoyl-lysophosphatidylcholine enhances human ether-a-go-go-related gene (HERG) K(+) channel function.

BACKGROUND: Lysophosphatidylcholine (LPC), a naturally occurring phospholipid metabolite, accumulates in the ischemic heart and causes extracellular K(+) accumulation and action potential shortening. LPC has been incriminated as a biochemical trigger of lethal cardiac arrhythmias, but the underlying mechanisms remain poorly understood. METHODS AND RESULTS: We studied the effect of 1-palmitoyl-LPC (Pal-LPC) on currents resulting from human ether-a-go-go-related gene (HERG) expression in human embryonic kidney (HEK) cells using whole-cell patch-clamp techniques. Bath application of Pal-LPC consistently and reversibly increased HERG current (I(HERG)). The effects of Pal-LPC were apparent as early as 3 minutes after application of the drug, reached maximum within 10 minutes, and were reversible on washout. Pal-LPC increased I(HERG) at voltages between -20 and +30 mV, with greater effects at stronger depolarization. However, Pal-LPC did not affect the voltage-dependence of I(HERG) activation. In contrast, Pal-LPC significantly shifted the inactivation curve toward more positive potentials, causing a mean 20.0+/-2.2 mV shift in half-inactivation voltage relative to control. CONCLUSIONS: Our results indicate that apart from being a well-recognized target for drug inhibition, I(HERG) can also be enhanced by natural substances. An increase in I(HERG) by Pal-LPC may contribute to K(+) loss, abnormal electrophysiology, and arrhythmia occurrence in the ischemic heart.

Arrhythmias, Cardiac↗
PubMed2001

[Diagnostic value of tau in cerebrospinal fluid in alzheimer disease].

OBJECTIVE: To search for reliable and quantitative biochemical marker for diagnosis of Alzheimer disease. METHODS: ELISA-double enzyme amplification assay was used to detect the total tau and abnormally hyperphosphorylated (p-tau) in cerebrospinal fluid specimens of patients with Alzheimer disease (AD, N = 52, 30 from the Netherlands and 22 from Wuhan and Haikou, China), vascular dementia (VD, N = 46, 18 from the Netherlands and 28 from Haikou), and non-neurological disease (N = 37, 13 from the Netherlands and 24 from Haikou) and of normal elderly controls (N = 56, 26 from the Netherlands, and 30 from Wuan and Haikou). RESULTS: The measurement of CSF specimens from Netherlands Brain Bank showed that the levels of total tau and p-tau in CSF specimens of AD patients were significantly higher than those in CSF of patients with VD and non-dementia neurological disorders, and of age-matched non-neurological normal controls. With CSF tau > or = 370 pg/ml as the marker for diagnosis of AD, the sensitivity, specificity, reliability as well as differentiation rate of AD from VD were 90.0%, 79.0%, 82.8% and 66.7%, respectively. With CSF p-tau > or = 120 pg/ml as the marker for diagnosis of AD, the sensitivity, specificity, reliability as well as differentiation rate of AD from VD were 93.3%, 89.5%, 90.8%, and 83.3% respectively. The measurement of total and phosphorylated taus in CSF specimens of AD and non-AD patients and normal controls collected in China showed the similar results; and the sensitivity, specificity, reliability as well as differentiation rate of AD from VD were 77.3%, 85.4%, 83.7% and 71.4% with CSF tau > or = 120 pg/ml as the marker for diagnosis of AD. There was no correlation between CSF tau and p-tau and age, sex, and seriousness of disease. CONCLUSION: Increased phosphorylated tau in human cerebrospinal fluid is a reliable biomarker for diagnosis of Alzheimer disease.

Aged↗
PubMed2001

Energy expenditure by intracerebroventricular administration of orexin to anesthetized rats.

Orexin-A and -B are hypothalamic neuropeptides that have been implicated in stimulating food intake and maintaining arousal. Because food intake is closely related to the control of energy homeostasis, we examined the effects of intracerebroventricular administration of orexins on O2 consumption (VO2), an index of energy expenditure, body temperature, skin temperature and heart rate (HR) in urethane-anesthetized rats. VO2 increased significantly after an orexin-A injection, and this increase was accompanied by a significant tachycardiac response. Orexin-B also increased VO2 and HR, although orexin-A was approximately 30 times more potent in eliciting these responses than orexin-B. The effects of orexin-A were dose dependent over the range of 1 pmol(-1) x nmol, whereas an injection of the saline vehicle had no effect. These findings suggest that centrally acting orexin-A functions to increase energy expenditure.

Animals↗