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Biomedical subjects

P Yao

Publications and source records attributed to P Yao.

At least 19 recordsLinked to original sources
PubMed2006

A low-cost, sustainable intervention for drinking reduction in the HIV primary care setting.

Excess drinking poses multiple substantial health risks to HIV-infected individuals. However, no published intervention studies have focused on drinking reduction as the main outcome in HIV primary care patients. An intervention in this setting must place minimal demands on pressured staff and resources. This pilot study tested such an intervention, which consisted of brief Motivational Interviewing (MI) and HealthCall, an automated daily telephone self-monitoring system based on Interactive Voice Response (IVR), designed to extend and enhance the effects of brief MI. Thirty-one patients entered the study, received a 30-minute MI and were instructed in daily use of the IVR system. They received graphical feedback on their daily drinking from the HealthCall database after 30 days. A statistically significant decrease in drinking was found over time, both as reported in daily IVR calls (beta = - 0.01, se 0.01, p=.03) and in follow-up interviews (beta = - 0.04, se 0.12, p=.02) at 60 days. The proportion of daily calls made supported the feasibility of the intervention. The results indicate that HealthCall is acceptable to a disadvantaged HIV patient population, and preliminary data support the efficacy of this intervention in reducing harmful drinking among HIV primary care patients.

Adult↗
PubMed2001

Taxane diterpenoids from the bark of Taxus yunnanensis.

Further investigation on the alcohol extract of the barks of Taxus yunnanensis led to the isolation of four taxoids, namely, 7beta-xylosyl-taxol D, taxuyunnanines P, Q and R, along with the known taxuyuntin G (2). Four are rearranged taxoids with an 11(15-->1)-abeotaxoid skeleton and an opened oxetane ring moiety. Structures were determined by spectroscopic and chemical means.

Diterpenes↗
PubMed2001

Hepatitis C virus infection and morphologic study in B lymphocytes of patient with hepatitis C.

OBJECTIVE: To study hepatitis C virus (HCV) infection in B lymphocytes of patients with hepatitis C and to establish a B cell line with HCV infection and observe the hepatitis C virus like particles. METHODS: A B lymphoblastoid cell line was established by Epstein-Barr virus induced transformation directly from peripheral blood mononuclear cells of a patient with hepatitis C. The HCV antigen and HCV RNA were detected by immunohistochemical technique. Reverse transcription-polymerase chain reaction(RT-PCR) and in situ hybridization and HCV particle were detected by electron microscopy. RESULTS: Positive HCV RNA was found in supernatants of B cell line. HCV Ag and HCV RNA were also showed positive. Electron microscopy observed HCV spherical virus like particles with a diameter of approximately 65 nm and 110 nm and the "bud mutation" of HCV in the cytoplasmic vesicles of B lymphocytes. CONCLUSIONS: HCV could infect B lymphocytes and replicate in the cell line. HCV particles are formed by "bud mutation" of HCV in the cytoplasmic vesicles of B-lymphocytes.

B-Lymphocytes↗
PubMed2001

[Study on the noninvasive measurement of cerebral oxygen saturation and cerebral phronetal function].

With the use of Near-infrared spectroscopy(NIRS), the noninvasive measurement of cerebral oxygen concentration can be achieved in vivo based on the Lambert-Beer Law. In this paper, we discuss the possibility of studying higher brain functions through a combination of cerebral oxygen saturation and cerebral function measurement. Event-related experiments are introduced to measure the cerebral phronetal function. Time domain curves show sight differences among these experiment results. However, with the aid of DFT, experiment data of all five human volunteers show that the frequency near 20 Hz or 40 Hz is evoked depending on the difficulty of the mental tasks. The results demonstrate the feasibility of cerebral function studies by means of cerebral oxygen saturation measurement analysis in the frequency domain.

Adult↗
PubMed2000

[Assessment on acute toxicity of combined pesticides].

The acute oral toxicity (LD50) of two pesticides combined from 3 categories of insecticides, i.e. organophosphates(OPs), pyrethroids and carbamates, was evaluated by Harris method on equal toxicity doses. The OPs compounds studied included: methylparathion, omethoate, methamidophos, phoxim, dichlorvos, profenofos, isocarbophos and malathion; the pyrethroids: alpha-cypermethrin, deltamethrin, fenvalerate and fenpropathrin; the carbamates: methomyl, isoprocarb and metolcarb. The mixtures of two OPs on the combination of dichlorvos plus omethoate and methamidophos plus profenofos showed additive effects, but methylparathion plus phoxim showed antagonistic effect. Most of the combination of OPs with pyrethroids showed synergistic effects, such as the mixtures of phoxim plus deltamethrin, phoxim plus alpha-cypermethrin, methlyparathion plus alpha-cypermethrin and ioscoarbphos plus fenpropthrin, with the exception of two mixtures showed additive effects: phoxim plus fenvalerate resulting in 1.5 times higher toxicity than expected, while dichlorvos plus deltamethrin resulting in less toxicity than expected. The effects of the mixtures of OPs and carbamates: phoxim plus methomyl and methamidophos plus metolcarb, were all additive, but the mixtures of he methylparathion plus methomyl showed antagonistic effect and malathion plus isoprocarb were synergistic. The biochemical mechanisms of changed toxicity of pesticides mixtures were discussed based on their toxicokinetics and toxicodynamics. It was concluded that the combined effects of insecticide mixtures were additive for OPs plus OPs or plus carbamates in most cased, but synergistic for OPs plus pyrethroids.

Animals↗
PubMed2000

Rearranged taxanes from the bark of Taxus yunnanensis.

Five new 11(15-->1)-abeo-taxane diterpenoids, taxuyunnanines K-O (1-5), were isolated from an ethanol extract of the bark of Taxus yunnanensis, and their structures were determined using MS and NMR techniques. Compounds 1/2 and 4/5 are rearranged taxane diterpenoids possessing an opened oxetane ring moiety at C4(20). Compounds 4/5 are rearranged taxoids lacking an oxygenated functionality at C-4.

Bridged-Ring Compounds↗
PubMed2000

[Study of hepatitis C virus specific immune responses in anti-HCV positive patients without hepatitis C viremia].

OBJECTIVE: To study the hepatitis C virus specific immune responses in anti - HCV positive patients without hepatitis C viremia. METHODS: 15 anti-HCV positive patients without hepatitis C viremia, 15 patients with chronic HCV infection and 15 normal controls were selected for this study. The T cell responses, NK cell (natural killer cells) activity, cytokine production and HCV specific antibodies were detected by MTT, LDH release and ELISA. RESULTS: Our study showed that the T cell proliferative reaction of patients without hepatitis C viremia was significantly higher than that of patients with chronic HCV infection and normal controls and the T cell response for HCV core antigen were higher than NS3 and N54, but there was no significant proliferative response to NS5 antigen. We also found that there were no differences in anti-HCV antibody production and NK cell activity between the two groups and the level of IFN-gamma in patients without hepatitis C viremia was higher than that in patients with persistent HCV infection. CONCLUSIONS: There are a lot of advantageous changes of HCV specific humoral and cellular immune response in anti-HCV positive patients without hepatitis C viremia, these immune responses may play a role in clearance of HCV.

Adult↗
PubMed1999

Effect of mutation at valine 61 on the three-dimensional structure, stability, and redox potential of cytochrome b5.

To elucidate the role played by Val61 of cytochrome b(5), this residue of the tryptic fragment of bovine liver cytochrome b(5) was chosen for replacement with tyrosine (Val61Tyr), histidine (Val61His), glutamic acid (Val61Glu), and lysine (Val61Lys) by means of site-directed mutagenesis. The mutants Val61Tyr, Val61Glu, Val61His, and Val61Lys exhibit electronic spectra identical to that of the wild type, suggesting that mutation at Val61 did not affect the overall protein structure significantly. The redox potentials determined by differential pulse voltammetry were -10 (wild type), -25 (Val61Glu), -33 (Val61Tyr), 12 (Val61His), and 17 mV (Val61Lys) versus NHE. The thermal stabilities and urea-mediated denaturation of wild-type cytochrome b(5) and its mutants were in the following order: wild type > Val61Glu > Val61Tyr > Val61His > Val61Lys. The kinetics of denaturation of cytochrome b(5) by urea was also analyzed. The first-order rate constants of heme transfer between cytochrome b(5) and apomyoglobin at 20 +/- 0.2 degrees C were 0.25 +/- 0.01 (wild type), 0.42 +/- 0.02 (Val61Tyr), 0.93 +/- 0.04 (Val61Glu), 2.88 +/- 0.01 (Val61His), and 3.88 +/- 0.02 h(-)(1) (Val61Lys). The crystal structure of Val61His was determined using the molecular replacement method and refined at 2.1 A resolution, showing that the imidazole side chain of His61 points away from the heme-binding pocket and extends into the solvent, the coordination distances from Fe to NE2 atoms of two axial ligands are approximately 0.6 A longer than the reported value, and the hydrogen bond network involving Val61, the heme propionates, and three water molecules no longer exists. We conclude that the conserved residue Val61 is located at one of the key positions, the "electrostatic potential" around the heme-exposed area and the hydrophobicity of the heme pocket are determinant factors modulating the redox potential of cytochrome b(5), and the hydrogen bond network around the exposed heme edge is also an important factor affecting the heme stability.

Animals↗
PubMed1999

Discordance between physicians and coders in assignment of diagnoses.

OBJECTIVE: To measure concordance between physicians and medical record coders in their assignment of diagnoses. DESIGN: Prospective cohort series. SETTING: Five hundred and fifty-bed, tertiary-care, university teaching hospital. Study participants. In-patients who were discharged from either the Cardiac Sciences Program (n=125), the Renal Program (n=43), or the HIV-AIDS Program (n=25) during the period May 18-July 1, 1995. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Physicians and coders assigned diagnoses for individual in-patients based on their independent interpretations of the patient chart and discharge summary sheet. All assigned diagnoses were coded using the ICD-9-CM classification system. Concordance was measured for the most responsible diagnosis and for all assigned diagnoses. Difference in calculated resource intensity weights based on physicians' and coders' assignment of diagnoses was also calculated. RESULTS: Concordance rates for the most responsible diagnosis in each program were: Cardiac Sciences [27%; 95% confidence interval (CI)=20-36%], Renal Program (35%; 95% CI=21-53%), and HIV-AIDS Program (20%; 95% CI, 6-41%). Concordance rates for all diagnoses per chart were similar: Cardiac Sciences (20%; 95% CI, 14-25%), Renal Program (25%; 95% CI, 20-33%), and HIV-AIDS Program (29%; 95% CI, 25-44%). Resource intensity weights assigned by coders for the Cardiac Sciences and HIV-AIDS Program were significantly higher than those assigned by the physicians.

Abstracting and Indexing↗
PubMed1998

Anti-aging effects of Bao-Chun-Wan on rats: a morphological ultrastructure study.

Bao-Chun-Wan, a Chinese prescription, is formulated according to the principle of tonifying the kidney for treatment of aging. Morphological study on the ultrastructure of laboratory albino rats treated with this formula showed an increase in thymic lymphocytes, which play an important role in the production of T cells. As to the liver cells, the formula has a protective effect and may induce enzymes enhancing oxidation and excretion of toxic substances. An increase in the Leydig's cell, which promotes reproductive hormone secretion, was also observed, but there was no obvious change in germinal cells. The above findings reported in this article have not been cited in any previous studies and are suggesting that the kidney tonifying formula may act through the mechanism of promoting body immune function, metabolism and biotransformation, and, therefore, result in anti-aging.

Aging↗
PubMed1998

[Studies on the experimental transmission of Rattus-borne Hantavirus by Ornithonyssus bacoti].

AIM: To demonstrate the role of rat mite (Ornithonyssus bacoti) in the transmission of Rattus-borne hemorrhagic fever with renal syndrome (HFRS). METHODS: In the transmission experiments, about 100 O. bacoti per pool were isolated and placed in a jar, unfed for 4 d at 23 +/- 1 degrees C. Suckling Wistar rats inoculated with Hantavirus strain Z45 or Seoul virus strain UR were placed in each jar for free attack by the mites for 12 hours. After 14 d the normal suckling Wistar rats were bitten by the mites. Fifteen days later, the lung tissues and sera of the infected rats were collected and detected for Hantaviral antigen by indirect fluorescent antibody technique (IFAT). For demonstration of the infection of O. bacti with Rattus-borne Hantavirus PCR technique was applied to detect Rattus-borne Hantaviral RNA. RESULTS: Sukling Wistar rats inoculted Hantavirus strain Z45 or Seoul virus strain UR were bitten by O. bacoti and then these mites were fed on 4 and 5 of normal suckling rats in each jar, respectively. The antigens of Hantavirus strain Z45 were positive in all the lungs of the normal rats bitten by the mites, the sera titers of the rats were from 1:10 to 1:40. The antigens were positive in 3 of the 4 rats, the sera titers were from 1:20 to 1:40. Both of the viruses could be maintained in O. bacoti for 22 days. The blocking test showed when 1:30 Hantavirus immunosera were exposed to the lung samples and then reacted with the sera from the patients with HFRS, all the specific fluorescence reactions of the samples were blocked, whereas the control group including the normal rat lung tissues and sera were all negative (Fig. 1). CONCLUSION: O. bacoti might play a role as the vector of HFRS and a reservoir host as well.

Animals↗
PubMed1997

Importance of a conserved phenylalanine-35 of cytochrome b5 to the protein's stability and redox potential.

Phenylalanine-35, which is a residue of the hydrophobic patch on the surface of cytochrome b5, has been mutated into Tyr35, His35 and Leu35 to elucidate the functions of the Phe35 and give further insight into the roles of the hydrophobic patch and/or aromatic network. The effects of these mutations on the heme environment, denaturation towards heating and the denaturant urea, redox potential and stability of protein were studied. The relative stability of cytochrome b5 and its mutants towards heating has the order Phe35Tyr > wild type > Phe35Leu > Phe35His in the oxidized state and wild type > Phe35Tyr > Phe35Leu > Phe35His in the reduced state. All the mutants exhibit decreased reduction potentials: Phe35Tyr -66 mV, Phe35His -51 mV and Phe35Leu -28 mV, which are more negative than that of the wild type. The order of redox potential reflects the relative stability in the oxidized and reduced states. A method of producing multiple mutants at a single site of a gene is also described for the first time.

Amino Acid Sequence↗
PubMed1996

Methyltransferase-specific domains within VP-39, a bifunctional protein that participates in the modification of both mRNA ends.

VP39 is a bifunctional vaccinia virus protein that acts as both a cap- dependent 2'-O-Methyltransferase and a poly(A) polymerase processivity factor. An analysis of C-terminal truncation mutants of a GST-VP39 fusion protein indicated the presence of a protease-sensitive C-terminal "tail" 36-43 amino acids in length that is non-essential for VP39 function. Fourteen new VP39 pointmutants, containing either single or multiple-clustered amino acid substitutions, were expressed in Escherichia coli. Of the eight that retained either one or both of the activities of VP39, seven were specifically methyltransferase-defective. None was specifically defective in adenylyltransferase stimulation. The nature of the methyltransferase defects in 10 of the methyltransferase-specific defectives, identified both herein and in a previous study (Schnierle BS, Gershon PD, Moss B, 1994, J biol Chem 269:20700-20706), was investigated using two novel substrate-binding assays. Three of the mutants (and possible a fourth), whose lesions were juxtaposed and centrally located within VP39, exhibited anomalous S-adenosyl-(L)-methionine (AdoMet) binding behavior, identifying residues important for AdoMet binding and possible also for catalysis. A surface plasmon resonance-based assay measured the interaction of VP39 with uncapped and 5'-cap 0-terminated oligo(A). A cap 0- dependent association-rate enhancement was observed for wild-type VP39 and 4 of the 10 mutant proteins. Two others were identified as defective in cap binding, and a third as partially defective. The lesions within the latter three mutants were closely apposed, and located toward the N-terminus of VP39. We have thus identified regions of VP39 important for interaction with its two substrates for cap-dependent methyltransferase activity: AdoMet and cap 0.

Amino Acid Sequence↗
PubMed1992

Modulation of dihydropyridine-sensitive gastric mucosal calcium channels by GM1-ganglioside.

1. A dihydropyridine-sensitive calcium channel complex was solubilized from gastric mucosal cell membranes and purified by affinity chromatography on wheat germ agglutinin. 2. The calcium channel complex labeled with [3H]PN200-110, when reconstituted into phosphatidylcholine vesicles, exhibited active 45Ca2+ uptake into intravesicular space as evidenced by La3+ displacement and osmolarity studies. The channel complex responded in a dose-dependent manner to dihydropyridine calcium antagonist, PN200-110, which at 0.5 microM exerted maximal inhibitory effect of 66% in 45Ca2+ uptake. 3. The uptake of 45Ca2+ into vesicle-reconstituted gastric mucosal calcium channel complex was inhibited by GM1-ganglioside. Maximum inhibitory effect was achieved at 10-15 nM GM1, at which point a 74% decrease in 45Ca2+ uptake occurred. Furthermore, GM1 also inhibited dihydropyridine binding to gastric mucosal membranes, indicating the extracellular orientation of calcium channel domains for GM1. 4. The ability of GM1 to modulate the intracellular calcium levels may be an important feature in gastric mucosal protection by this ganglioside.

Animals↗
PubMed1992

GM1-ganglioside regulation of EGF-induced gastric mucosal calcium channel activation.

1. Calcium channels, isolated from gastric epithelial cell membranes when reconstituted into phosphatidylcholine vesicles exhibited active 45Ca2+ uptake as evidenced by a dose dependent response to calcium channel activator, BAY K8644, and antagonist, PN200-110. 2. The channels on epidermal growth factor (EGF) binding in the presence of ATP showed an increase in tyrosine phosphorylation of 55 and 170 kDa calcium channel proteins. Such phosphorylated channels following reconstitution into the vesicles displayed a 48% greater 45Ca2+ uptake than that of the controls. 3. The binding of EGF to calcium channel protein was inhibited by GM1-ganglioside reaching maximum inhibition of 65% at 40 nM GM1. In contrast, calcium channel antagonist, PN200-110, had no effect on EGF binding. 4. The EGF-stimulated calcium channel protein phosphorylation was inhibited by GM1. This inhibitory effect was mainly reflected in the decrease of tyrosine phosphorylation of 55 and 170 kDa proteins. 5. The results suggest the participation of GM1-ganglioside in the regulation of EGF-stimulated gastric mucosal calcium channel activation.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1992

Effect of GM1-ganglioside on gastric mucosal epidermal growth factor and platelet-derived growth factor receptor expression.

The effect of intragastric administration of GM1-ganglioside on the expression of gastric mucosal epidermal growth factor (EGF) and platelet derived growth factor (PDGF) receptors was investigated. Gastric mucosal cell membranes were isolated from the stomach of groups of rats, one receiving twice daily for 3 consecutive days a dose of 0.25 mg/100g GM1-ganglioside, and the other only vehicle. Binding assays revealed the presence of both types of receptors, activation of which led to the elevation of tyrosine kinase activity as evidenced by a marked increase in membrane protein tyrosine phosphorylation patterns. The specific receptor binding in the control group was 2.47 fmol/mg protein for EGF and 1.46 fmol/mg protein for PDGF, whereas the respective binding values in the GM1-ganglioside treated group increased by 45% and 38%. The results suggest that GM1-ganglioside is capable of enhancement of gastric mucosal EGF and PDGF receptor activities.

Animals↗