Search PubMed⌕ Search

Biomedical subjects

Yu Wang

Publications and source records attributed to Yu Wang.

342 records · Page 19Linked to original sources
PubMed2002

[Quantitative determination of morphine in opium powder by addition and correlation method using capillary electrophoresis].

The morphine in opium powder has been quantitatively determined by addition and correlation method (ACM), in which capillary zone electrophoresis was applied, and the average recovery was 100.6%. The relative standard deviation (RSD) of migration time was not more than 2.4%, the RSD of relative migration time was not more than 1.1%, and the RSD of the relative area was not more than 0.51%. Meanwhile, the contrast test has been done by the calibration curve method with an internal standard correlation. The content of morphine in opium powder determined by ACM was the same as that by using the calibration curve method with an internal standard correlated. The study shows that ACM is simple, quick and accurate.

Calibration↗
PubMed2002

[Quantitative determinations of glycyrrhizic acid, glycyrrhetinic acid, morphine and sodium benzoate in compound liquorice tablets by capillary zone electrophoresis].

Capillary zone electrophoresis (CZE) was used to quantitatively determine the contents of glycyrrhizic acid, glycyrrhetinic acid, morphine and sodium benzoate in compound liquorice tablets. The detection wavelength was 228 nm and the applied voltage was 14 kV. Borax solution of 50 mmol/L was used as the background electrolyte and hydrochlorothiazide as the internal standard. There were all good linear relationships between the concentrations and the relative areas of glycyrrhizic acid, glycyrrhetinic acid, morphine and sodium benzoate. Their average recoveries were 98.2%, 97.3%, 97.1% and 97.5%, respectively. The method is simple, rapid and accurate.

Antitussive Agents↗
PubMed2002

[Cloming, sequence analysis of imidase gene from Alcaligenes eatrophus and its expression in E. coli].

A hydantoin-cleaving microorganism 112R4 is screened and identified to be Alcaligenes eutrophus. The resting cell of Alcaligenes eutrophus 112R4 can catalyze the hydrolysis of hydantoin, dihydropyrimidine and succinimide effectively, but not function to 5-monosubstituted hydantoins or 5,5'-disubstituted hydantoins. The microorganism can utilize succinimide as a sole carbon source and nitrogen source, which indicates the presence of a complete transformation pathway of succinimide, and a hydantoin-cleaving enzyme, imidase, is suggested to be contained in this metabolic pathway. A 6 kb EcoRI-EcoRI fragment isolated from the genome DNA of Alcaligenes eutrophus 112R4 is shown to be correlative with the transformation of succinimide. A 2 kb DNA fragment containing the gene of imidase is subcloned and sequenced. Deletion analysis verifies that one open reading frame of 876 nucleotides, which encodes a peptide of 291 amino acids, with a calculated molecular weight of 33688, is responsible for the encoding of imidase. This is the first report of the nucleotide and amino acid sequences of imidase (GenBank accession number: AF373287). A homology search performed in protein database reveals an identity of 14% with polysaccharide deacetylase conserved domain, an identity of 60% with N-terminal 20 amino acids of Blastobacter sp. A17p-4, but no apparent similarity with all known cyclic-amide-cleaving enzymes. This result suggested that the imidase should be classified as a new member of cyclic amidases. Under the control of lac promoter and IPTG induction, the imidase activity of transformed E. coli reached 3200 U/L, which is about 7-fold higher than that of gene donor strain.

Alcaligenes↗
PubMed2002

[Cloning and sequence analysis of aspartokinase genes from Corynebacterium crenatum].

Aspartokinase genes (ask) from wild-type Corynebacterium crenatum AS1.542 and an AEC-resistant mutant Corynebacterium crenatum CD945 were cloned and sequenced. Analysis of ask sequence shows a exchange in a single base pair at position 1199 from T to C, leading to an amino acid change in the beta subunit of Aspartokinase. Leu80 in the wild-type is converted to Pro80 in the feedback-resistant enzyme. The substitution is located in ACT domain, a region regulated by concentration of lysine. The ORF sequence of ask from C. crenatum AS 1.542 shows homologies of 97.23%, 97.55% and 97.62% to those from C. glutamicum, C. flavum and B. lactofermentum. And the amino acid sequence deduced from ORF displays homologies of 99.76%, 99.52% and 99.76%, respectively. But there is much variation in the upstream sequence of C. crenatum AS 1.542 ask promoter compared to those from other Corynebacteria.

Amino Acid Sequence↗
PubMed2002

[The change of nitric oxide to PGE2 ratio in uterine tissues of endotoxin-treated pregnant mice].

OBJECTIVE: To investigate the relationship between preterm labour and the ratio of nitric oxide to prostaglandin E2 in uterine tissues. METHODS: Pregnant mice were given lipopolysaccharide(LPS), LPS + DETA/NO, LPS + DETA or saline solution respectively by intraperitoneal injection on day 16 of gestation. The delivery time of each mouse was recorded. Four separate groups of mice were given treatment as described. And they were killed at 12 hours after that. Serum progesterone, uterine production of nitrite and PGE2 were measured. RESULTS: Uterin production of nitrite and PGE2 in LPS-treated mice was significantly higher than that in control mice. In contrast the ratio of nitrite to PGE2 decreased. Accompanied by the fall of serum progesterone level DETA/NO rather than DETA could partially reversed the changes. CONCLUSION: Infection can induce preterm labor by altering the ratio of nitric oxide to PGE2. Nitric oxide can prevent the decrease of nitric oxide to PGE2 ratio possibly by attenuating the fall of serum progesterone. And it can prevent LPS-induced preterm labor.

Animals↗
PubMed2002

[Transfusion of activated immune cells induced fluctuations of HCV titer without mutations in hepatitis C virus core and E2 region CTL epitopes].

OBJECTIVE: To investigate the variations of HCV core and E2 region epitopes during transfusion of activated immune cells. METHODS: Four patients receiving transfusion of activated immune cells were under continuously observation. HCV titers were measured by quantitive PCR. HCV core and E2 regions were cloned and sequences were analyzed by computer software. RESULTS: During the follow-up the serum ALT levels and the HCV virus titers fluctuated greatly in each of these persons. After transfusion, no significant variations were observed in HCV core and E2 coding regions. CONCLUSIONS: The alteration of host immune attacks could induce the fluctuations of HCV load without any mutations in the currently observed coding genes of the epitopes.

Adult↗
PubMed2002

Endoscopic sphincterotomy with needle-shaped knife: report of 476 cases.

OBJECTIVES: To evaluate endoscopic duodenal sphincterotomy and improve its success rate. METHODS: Needle-shaped knife was used for endoscopic sphincterotomy (EST) in 476 patients with biliary or pancreatic diseases from March 1995 to October 2000. RESULTS: Direct incision was made in 243 patients, papillary fenestration in 89, and opposite incision in 144. The papilla located beside and in the diverticulum in 56 and 12 patients, respectively. EST emergency was made in 147 patients. ERCP after EST because of the difficulty in intubation was made successfully in 62 patients. Mild complications occurred in 14 patients (2.94%), all of whom were cured after symptomatic treatment. CONCLUSIONS: EST with needle-shaped knife has such advantages as safety in operation and convenience in incision. It is suitable for the papilla with different shape, with a higher success rate.

Adolescent↗
PubMed2002

Surgical treatment of portal hypertension.

Portal hypertension is a common disease with high mortality and serious influence on the life quality of patients. At present, shunt and disconnection are commonly used for the treatment of portal hypertension. In recent years, combined procedures of shunt and disconnection have evoked the potential interest of surgeons. Initial experimental studies and clinical observations showed that the combined procedures are ideal for treating portal hypertension. Transjugular intrahepatic portacaval shunt (TIPS) is a new minimally invasive technique in treating portal hypertension. Some surgeons have tried to perform disconnection under laparoscopy with success. Liver transplantation will be the focus of portal hypertension surgery in the future.

Gastroenterology↗
PubMed2002

[A new program-controlled telemetry technology for pacemakers].

This thesis is about a new technology of program-controlled telemetry for pacemakers. The system utilizes digital logic circuit design, and the program-controlled part uses single chip to control for display and debug. PWM and reflectance telemetry may improve the preciseness and correctness of signal transmission, and reduce the power consumption of pacemakers and prolong the lifetime.

Electrocardiography↗
PubMed2001

Genomic and evolutionary characterization of TT virus (TTV) in tupaias and comparison with species-specific TTVs in humans and non-human primates.

TT virus (TTV) was recovered from the sera of tupaias (Tupaia belangeri chinensis) by PCR using primers derived from the noncoding region of the human TTV genome, and its entire genomic sequence was determined. One tupaia TTV isolate (Tbc-TTV14) consisted of only 2199 nucleotides (nt) and had three open reading frames (ORFs), spanning 1506 nt (ORF1), 177 nt (ORF2) and 642 nt (ORF3), which were in the same orientation as the ORFs of the human prototype TTV (TA278). ORF3 was presumed to arise from a splicing of TTV mRNA, similar to reported human TTVs whose spliced mRNAs have been identified, and encoded a joint protein of 214 amino acids with a Ser-, Lys- and Arg-rich sequence at the C terminus. Tbc-TTV14 was less than 50% similar to previously reported TTVs of 3.4-3.9 kb and TTV-like mini viruses (TLMVs) of 2.8-3.0 kb isolated from humans and non-human primates, and known animal circoviruses. Although Tbc-TTV14 has a genomic length similar to animal circoviruses (1.8-2.3 kb), Tbc-TTV14 resembled TTVs and TLMVs with regard to putative genomic organization and transcription profile. Conserved motifs were commonly observed in the coding and noncoding regions of the Tbc-TTV14 genome and in all TTV and TLMV genomes. Phylogenetic analysis revealed that Tbc-TTV14 is the closest to TLMVs, and is closer to TTVs isolated from tamarin and douroucouli than to TTVs isolated from humans and chimpanzees. These results indicate that tupaias are naturally infected with a new TTV species that has not been identified among primates.

Amino Acid Sequence↗
PubMed1997

Chelation-Assisted C-O Bond Cleavage of Ortho Esters. A Convenient Synthesis of myo-Inositol Derivatives Having Free Hydroxy Group(s) at Specific Position(s).

Reactions of ortho esters of myo-inositol 8 or 10 with 1-2 equiv of Grignard reagents in benzene-ether yield regio- and stereoselectively the corresponding ring opening products having a free hydroxy group at C-1. The regioselectivity is rationalized owing to the presence of the 2-methoxy group which will serve as an auxiliary to form a chelation complex 12 with magnesium. Inositol derivatives having two free hydroxy group at C-1 and C-3 positions can be achieved from reactions of 6 or 8 with excess Grignard reagents or under more drastic conditions. The reaction of 8b with excess LiAlH(4)/AlCl(3), on the other hand, yields the corresponding 1,5-diol 19.

Journal Article↗
PubMed1997

Substitution Reactions of Aluminum Organoamide Complexes [Al(&mgr;-NR(2))(n)Cl(3-n)](2) (R = Et, (i)Pr; n </= 3) with LiNR'R" (R' = R" = (i)Pr, Et; R' = H, R" = (i)Pr): Crystal Structure of [Al(&mgr;-NEt(2))(N(i)Pr(2))X](2) (X = Cl, H) and AlCl(3)(N(i)PrH(2))(2){Al(NH(3))(NH(2))[Al(N(i)PrH)(N(i)Pr)Cl](2)}(2).

As part of our ongoing study of different substituents of Al(2)N(2) ring systems, the synthesis, structural characterization, and spectroscopic studies on several amido derivatives of four-coordinated aluminum are described. The compounds Al(2)(NEt(2))(2)(N(i)Pr(2))(2)Cl(2), 1, Al(2)((N(i)Pr(2))(4)Cl(2), 2, Al((N(i)Pr(2))(3), 3, Al(NEt(2))(3), 4, {Al(N(i)PrH)(3)}(3), 5, Al(2)(NEt(2))(2)(N(i)Pr(2))(2)H(2), 6, and AlCl(3)(N(i)PrH(2))(2){Al(NH(3))(NH(2))[Al(N(i)PrH)(N(i)Pr)Cl](2)}(2), 7, were synthesized by substitution reactions and characterized by mass spectra, IR spectra, elemental analysis, and (1)H, (13)C, and (27)Al NMR data. The structures of three compounds, viz., 1, 6, and 7, have been determined by single-crystal X-ray diffraction analysis. Crystal data with Mo Kalpha (1 and 7, lambda = 0.710 73 Å) or Cu Kalpha (6, lambda = 1.541 78 Å) radiation: (1) Al(2)N(4)C(20)H(48)Cl(2), a = 7.747(2) Å, b = 9.648(2) Å, c = 10.110(3) Å, alpha = 102.91(2) degrees, beta = 83.54(2) degrees, gamma = 110.19(2) degrees, triclinic, space group P&onemacr;, Z = 1, R = 0.053 for 1789 (I > 3sigma(I)) reflections; (6) Al(2)N(4)C(20)H(50), a = 15.088(2) Å, b = 14.506(3) Å, c = 12.439(3) Å, orthorhombic, space group Cmca (No. 64), Z = 4, R = 0.045 for 701 (I > 3sigma(I)) reflections; (7) Al(7)N(14)C(30)H(86)Cl(7), a = 29.914(9) Å, b = 10.197(3) Å, c = 20.525(5) Å, beta = 90.99(4) degrees, monoclinic, space group C2/c, Z = 4, R = 0.042 for 2472 (I > 2sigma(I)) reflections.

Journal Article↗
PubMedDate not supplied

Phosphorescent pH sensors and switches with substitutionally tunable response range based on photo-induced electron transfer.

According to the principle of photo-induced electron transfer (PET), five aminomethyl-bromonaphthalene phosphoroionophores with long lifetimes (to ms) were synthesized, all of them working well in beta-cyclodextrin (beta-CD) aqueous solutions. They form a family of phosphorescent sensors with pH-dependent spectral properties. For all the compounds, the fully protonated form exhibits the highest phosphorescence emission intensity and the proton-free form of the sensor is weakly emissive, due to the designed PET process. The sensors also show the expected pH dependence of phosphorescence quantum yields. Responses of the sensors are tuned by variation of substituent. The pH response ranges for 1-5 were 4.3-6.5, 3.5-10.5, 3.4-10.5, 3.4-10.5 and 3.4-6.1, respectively.

Cations↗
PubMedDate not supplied

Magnetic resonance imaging of acute reperfused myocardial infarction: intraindividual comparison of ECIII-60 and Gd-DTPA in a swine model.

PURPOSE: To compare a necrosis-avid contrast agent (NACA) bis-Gd-DTPA-pamoic acid derivative (ECIII-60) after intracoronary delivery with an extracellular agent Gd-DTPA after intravenous injection on magnetic resonance imaging (MRI) in a swine model of acute reperfused myocardial infarction (MI). METHODS: Eight pigs underwent 90 min of transcatheter coronary balloon occlusion and 60 min of reperfusion. After intravenous injection of Gd-DTPA at a dose of 0.2 mmol/kg, all pigs were scanned with T1-weighted MRI until the delayed enhancement of MI disappeared. Then they were intracoronarily infused with ECIII-60 at 0.0025 mmol/kg and imaged for 5 hr. Signal intensity, infarct-over-normal contrast ratio and relative infarct size were quantified, compared, and correlated with the results of postmortem MRI and triphenyltetrazolium chloride (TTC) histochemical staining. RESULTS: A contrast ratio over 3.0 was induced by both Gd-DTPA and ECIII-60. However, while the delayed enhancement with Gd-DTPA virtually vanished in 1 hr, ECIII-60 at an 80x smaller dose depicted the MI accurately over 5 hr as proven by ex vivo MRI and TTC staining. CONCLUSION: Both Gd-DTPA and ECIII-60 strongly enhanced acute MI. Comparing with fading contrast in a narrow time window with intravenous Gd-DTPA, intracoronary ECIII-60 persistently demarcated the acute MI, indicating a potential method for postprocedural assessment of myocardial viability after coronary interventions.

Animals↗
PubMedDate not supplied

The origin of sympathetic outflow in heart failure: the roles of angiotensin II and nitric oxide.

The regulation of sympathetic nerve activity in chronic heart failure (CHF) has been an area of renewed investigation. Understanding the central mechanisms that are responsible for sympatho-excitation in this disease state may help in reducing the deleterious effects of chronic sympatho-excitation. This review will summarize our understanding of abnormal reflex control of the circulation in CHF. The roles of the arterial baroreflex, the chemoreflex, the cardiac sympathetic afferent reflex and the cardiopulmonary reflex are discussed. New experimental techniques that allow genetic manipulation of substances such as nitric oxide synthase in discrete areas of the brain aid in clarifying the role of NO in the modulation of sympathetic tone in the CHF state. Lastly, clinical implications of this work are discussed.

Angiotensin II↗
PubMedDate not supplied

Automatic frequency alignment and quantitation of single resonances in multiple magnetic resonance spectra via complex principal component analysis.

Several algorithms for automatic frequency alignment and quantitation of single resonances in multiple magnetic resonance (MR) spectra are investigated. First, a careful comparison between the complex principal component analysis (PCA) and the Hankel total least squares-based methods for quantifying the resonances in the spectral sets of magnetic resonance spectroscopy imaging (MRSI) spectra is presented. Afterward, we discuss a method based on complex PCA plus linear regression and a method based on cross correlation of the magnitude spectra for correcting frequency shifts of resonances in sets of MR spectra. Their advantages and limitations are demonstrated on simulated MR data sets as well as on an in vivo MRSI data set of the human brain.

Brain↗