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Biomedical subjects

P Tao

Publications and source records attributed to P Tao.

At least 19 recordsLinked to original sources
PubMed2001

[Anti-hepatitis B virus effects of lamivudine and other five drugs in vitro].

OBJECTIVE: To find out reliable index for evaluating the anti-hepatitis B virus (HBV) effects in vitro of lamivudine (3TC) and other five anti-HBV drugs. METHODS: The contents of human hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) and hepatitis B virus DNA (HBV DNA) in the culture supernatant of 2.2.15 cell line transfected with hepatitis B virus gene were tested after the six anti-hepatitis B virus drugs were added respectively, and the accordance of different indexes was compared. RESULTS: All six drugs, within a certain range, exercised only weak or no inhibitive effect on extracellular HBsAg and HBeAg secreted by 2.2.15 cell line. Lamivudine and 2 3-dideoxy-3-fluoroguanosine (FLG) significantly inhibited the level of HBV DNA, with the 50% inhibition concentration(IC50) of 0.31 mumol/L and 0.53 mumol/L respectively. Acyclovir (ACV) and interferon-alpha(IFN-alpha) also inhibited the HBV DNA with the IC50 of 0.33 mmol/L and 96.18 U/ml respectively. Phosphonoformate (PFA) and ribavirin (RBV) showed none effect on HBV DNA content even at the maximum non-toxic concentrations. CONCLUSION: There is not accordance between the expression activities of proteins of HBsAg and HBeAg and the inhibition of HBV DNA level. HBV DNA level better reflexes the inhibitive effect of different drugs and can be used as an important index for evaluation of anti-HBV effect in vitro.

Antiviral Agents↗
PubMed2001

Protein ligand docking based on empirical method for binding affinity estimation.

An empirical protein-ligand binding affinity estimation method, SCORE, was incorporated into a popular docking program, DOCK4. The combined program, ScoreDock, was used to reconstruct the 200 protein-ligand complex structures and found to give good results for the complexes with high binding affinities. A quality assessment method for docking results from ScoreDock was developed based on the whole test set and tested by additionally selected complexes. The method significantly improves the docking accuracy and was shown to be reliable in docking quality assessment. As a docking tool in structural based drug design, ScoreDock can screen out final hits directly based on the predicted negative logarithms of dissociation equilibrium constants of protein-ligand complexes, and can explicitly deal with structure water molecules, as well as metal atoms.

Computer Simulation↗
PubMed2000

Antiviral activity of mixed-valence rare earth borotungstate heteropoly blues against influenza virus in mice.

The acute and accumulated toxicity of the rare earth borotungstate heteropoly blues, HPB-2, Ce2H3[BW9(VI)W2(V)Mn(H2O)O39].12H2O, which is active against influenza virus in Kunming mice, were investigated in Kunming mice following oral and intraperitoneal administration. The activity of HPB-2 against influenza virus (FM1) in the mice was then investigated. HPB-2, given either orally (p.o.) or intraperitoneally (i.p.), was shown to have activity. HPB-2 was shown to be more effective than the positive control, ribavirin, and it was also found that i.p. administration was more effective than p.o. administration.

Administration, Oral↗
PubMed2000

[Selective inhibition of HSV-1 DNA and protein synthesis by antiviral antibiotic 17997].

OBJECTIVE: To study the effects of 17997 on the HSV-1 DNA and protein synthesis. METHODS: DNA synthesis was determined by isopycnic separation of cellular and viral DNA in CsCl gradients centrifugation. Protein synthesis was determined by SDS-PAGE and Western blot. RESULTS: The inhibition rates of 0.5 micromol/L, 1.0 micromol/L, 2.0 micromol/L and 4.0 micromol/L of 17997 on HSV-1 DNA synthesis were 63.1%,74. 1%, 93.9% and 100%, respectively. 4.0 micromol/L of 17997 did not inhibit VERO cell DNA synthesis. The above concentrations of 17997 did not show any inhibitory effects on cellular protein synthesis, but selectively inhibited on viral protein synthesis. CONCLUSIONS: 17997 selectively displayed inhibitive effects on HSV-1 DNA and protein synthesis.

Animals↗
PubMed2000

[The efficacy of antiviral antibiotic 17997 on treatment of HSV-1 infected guinea pig skin infection].

OBJECTIVE: To study the treatment efficacy of antiviral antibiotic 17997 against HSVl infected guinea pig skin infection. METHODS: Guinea pig skin was infected by HSV1. 24hrs or 48hrs of post infection local treatment of 0.3% 17997 cream was started, tid for five days. In the mean time, acyclovir treatment, cream treatment and virus control were included. RESULTS: Local treatment of 0.3% 17997 cream showed therapeutic effects, it reduced the average scores of skin lesion, accelerated crusting-time and healing-time. CONCLUSIONS: 0.3% 17997 cream showed significant treatment efficacy when compared with cream and virus controls by reducing skin lesion scores and healing-time. The treatment efficacy of 3.0% acyclovir cream was a little bit better than 0.3% 17997 cream.

Acyclovir↗
PubMed1999

Proteoglycan (aggrecan)-induced arthritis in BALB/c mice is a Th1-type disease regulated by Th2 cytokines.

In animal models of arthritis induced with Ags or infectious agents, disease severity correlates with a dominant Th1-type response characterized by a higher ratio of IFN-gamma to IL-4. Analysis of BALB/c mice revealed a genetic predisposition toward developing CD4+ Th2-type responses. The bias toward an IL-4-dominant response in BALB/c mice protects mice from severe Lyme-induced arthritis and spontaneous autoimmune disease. Since BALB/c mice immunized with proteoglycan develop severe arthritis, we were interested in testing whether arthritis is associated with a Th2-type response and thus is different from other arthritic models. BALB/c mice immunized with proteoglycan generated a higher ratio of IFN-gamma to IL-4 that peaks at the onset of arthritis. We investigated whether when Th1 cells were dominant, disease outcome could be modified with pharmacological amounts of Th2 cytokines. Treatment with IL-4 prevented disease and induced a switch from a Th1-type to a Th2-type response. Proinflammatory cytokine mRNA transcripts were reduced in joints of cytokine-treated mice. Th2 cytokine therapy at the time of maximum joint inflammation also suppressed symptoms of disease. Despite the predisposition of BALB/c mice to a Th2-type response, proteoglycan-induced arthritis is a Th1-type disease. The effectiveness of IL-4 treatment was particularly striking because in other models of arthritis, treatment in a similar manner with IL-4 was not sufficient to inhibit arthritis. The effective control of arthritis and the switch from a Th1 to Th2 response suggest that levels of endogenous IL-4 in BALB/c mice may increase their responsiveness to Th2 cytokine therapy.

Acute Disease↗
PubMed1999

Changes in frequency of HIV-1-specific cytotoxic T cell precursors and circulating effectors after combination antiretroviral therapy in children.

Combination antiretroviral therapy has had a major role in reducing human immunodeficiency virus type 1 (HIV-1) plasma viral loads in HIV-1-infected adults but a variable effect in infants, in whom complete viral suppression appears to be less readily achieved. In adults, after the reduction in plasma viremia, there is a decrease in the numbers of circulating cytotoxic T cell (CTL) effectors and precursors in the majority of patients. This longitudinal study assessed the effect of combination drug therapy on the frequency of HIV-1-specific CTL responses in 8 HIV-1-infected children. Following treatment, the frequency of HIV-1-specific CTL responses initially increased, especially in children with incomplete viral suppression but with increasing CD4+ cell counts. In children with complete viral suppression, the frequency of HIV-1-specific CTL responses decreased, suggesting that viral replication is required to maintain CTL responses in the systemic circulation.

Anti-HIV Agents↗
PubMed1999

[Hip ambulatory abduction in the treatment of Legg-Calve-Perthes disease].

Forty-eight cases of Legg-Calve-Perthes disease were treated with hip ambulatory abduction brace. The children were able to walk, sit, climb, or squat with the brace. Thirty-nine cases were followed up more than three years. The total excellent rate was 82%. The result of Catterall Grade I-II cases was all excellent. The excellent rate was 80% below five-year-old cases of Catterall III-IV during the start of the treatment and 66.6% above five. With the active hip abduction and internal rotation, the femoral head was held well. The results show that the method is simple and with no operation and with satisfactory effect of the treatment.

Braces↗
PubMed1996

[Effects of 5-HT on activity of arcuate neurons of rat hypothalamic slices].

Extracellular recordings were made from 176 spontaneous discharging units in the arcuate nucleus of rat hypothalamic slices. Depending on the patterns of discharge, the units were divided into three types; slow irregular (76%), fast continuous (26.5%) and phasic units (6.3%). The effect of 5-HT on the different types of units were observed. The results indicated that most of neurons were inhibited by 5-HT, and only a small portion of the cells showed excitation and a few of the slow irregular units showed "excitation after inhibition". With 5-HT 10(-6) mol/L we found that 12 units inhibited by 5-HT could not be reversed by CHD, while the 4 inhibited units could be partly or completely reversed by MSG. 4 of the 7 neurons inhibited by 5-HT were partly blocked by Pindobind-5-HT1A but not for the remaining 3 neurons. The results suggest that the inhibitory effect of 5-HT on arcuate neurons may be mediated by 5-HT1 receptor, while some by 5-HT1A receptor.

Animals↗
PubMed1993

A novel detection assay for the early diagnosis of HIV-1 infected infants.

This investigation compares the results of a new method of diagnosing HIV-1 infection in infants < 6 months of age with currently employed techniques including cocultivation, the polymerase chain reaction (PCR), serum p24 antigen, and in vitro antibody production (IVAP) measurements. The new method, called in vitro antigen (IVAG), measures p24 antigen released into culture supernatants of peripheral blood mononuclear cells that are incubated with Epstein-Barr virus (EBV). No activated donor lymphocytes or interleukin 2 (IL-2) are added to the culture. Using this technique, HIV-1 infection was detected in 15 of 17 HIV-1-infected infants < 2 months of age, including 3 of 7 infants tested at birth, and 15 of 15 HIV-1-infected infants between 2 and 6 months of age. None of 83 determinations of 15 uninfected infants were positive. These results were found to be comparable to results obtained by the traditional cocultivation technique and the polymerase chain reaction. Because of its simplicity and reduced cost, this sensitive and specific assay could be a valuable addition to the current methods of diagnosis of HIV-1 infection in young infants.

Cells, Cultured↗
PubMed1992

[The inhibitory effects of catechin derivatives on the activities of human immunodeficiency virus reverse transcriptase and DNA polymerases].

Catechin derivatives including (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC) and green tea extract (GTE) were found to inhibit the activities of cloned human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT), duck hepatitis B virus replication complexes reverse transcriptase (DHBV RCs RT), herpes simplex virus 1 DNA polymerase (HSV-1 DNAP) and cow thymus DNA polymerase alpha (CT DNAP alpha). EGCG and ECG were shown to be very potent inhibitors of HIV-1 RT. According to the IC50 values for HIV-1 RT, these compounds can be ordered as EGCG 0.0066 mumol/L > ECG 0.084 mumol/L > GTE 0.1 microgram/ml > EGC 7.2 mumol/L. DHBV RCs RT was the least sensitive to these compounds. Kinetic study showed that EGCG exerts a mixed inhibition with respect to external template inducer poly (rA).oligo (dT) 12-18 and a noncompetitive inhibition with respect to substrate dTTP for HIV-1 RT. Bovine serum albumin significantly reduced the inhibitory effects of catechin analogues and GTE on HIV-1 RT. In tissue culture GTE inhibited the cytopathic effect of coxsackie B3 virus, but did not inhibit the cytopathic effects of HSV-1, HSV-2, influenza A or influenza B viruses.

Animals↗
PubMed1992

[Isolation and characterization of mutactimycin-producing mutant].

Natural non-antibiotic producing Streptomyces sp. 1254 was mutagenized by UV irradiation and two active mutants were isolated. Mutant 113 produced novel anthracycline compounds designated mutactimycins. Mutactimycin A was active against the bacteriophage of Bac. subtilis and some viruses in tissue culture. The mutant 2-6 synthesized a basic water-soluble antimicrobial antibiotic. Chemical analysis of the whole cell hydrolysate and the morphological characterization showed that the strain 1254 and its mutant 2-6 were of chemotype I, belonging to the genus of Streptomyces, and the mutant 113 was of chemotype IV without mycolic acid. Co-synthesis test of strain 1254 and a blocked mutant of strain 113 gave the active compounds identical with mutactimycins. Using the actI gene as a probe, the Southern hybridization revealed homology between the actinorhodin polyketide biosynthase gene and the total DNA of the strain 1254. Based on these data it was deduced that Streptomyces sp. 1254 should have a biosynthesis pathway for mutactimycin, but some of its genes might fail in expression and mutagenesis would make the silent gene(s) active.

Antibiotics, Antineoplastic↗
PubMed1991

Intravenous recombinant tissue-type plasminogen activator in acute myocardial infarction.

The efficacy and safety of intravenously administered recombinant tissue-type plasminogen activator (rt-PA, Boehringer Ingelheim Corp.) was investigated in 10 patients with acute myocardial infarction (AMI). rt-PA was given as a 10 mg bolus dose followed by infusions of 50 mg, 20 mg and 20 mg in three successive hours. All patients underwent baseline coronary angiography before thrombolytic therapy. Ninety minutes after the initiation of rt-PA infusion, recanalization of infarct-related coronary arteries as confirmed by angiography was achieved in 7 patients. The largest reduction in circulating fibrinogen was observed 4 to 6 h after the start of rt-PA infusion--14.3%. Moderate hemorrhage at the sites of arterial puncture occurred in 2 cases, probably as a result of heparin anticoagulation. No other side effects occurred. So rt-PA is an effective and safe thrombolytic agent.

Aged↗
PubMed1990

The characterization of EIAV reverse transcriptase and its inhibition by 5'-triphosphates of 2'-deoxyuridine analogs, PFA and PAA.

A characterization of equine infectious anemia virus reverse transcriptase (EIAV RT) and its inhibition by 5'-triphosphate analogs was undertaken to explore the possibility of using EIAV RT as an in vitro model for studying human immunodeficiency virus (HIV). EIAV RT activity was found to be dependent on the bivalent cations Mg++ and Mn++. The optimal pH for enzyme reaction was pH 8.2. EIAV RT preferred a 70 mmol/L concentration of monovalent salts. Phosphonoformic acid (PFA) was an active inhibitor of EIAV RT, but phosphonoacetic acid (PAA) and N-ethylmaleimide (NEM) were not. The inhibition of EIAV RT activity by 5'-triphosphates of nucleoside derivatives was in the following decreasing order: FLTTP greater than AZTTP greater than nPrearaUTP greater than nPredUTP = CEdUTP greater than EtdUTP greater than nPrdUTP greater than HMdUTP. nPrearaUTP was a linear competitive and PFA a linear noncompetitive inhibitor of EIAV RT with respect to dTTP. Apparent Kis and Kii were 1.5 and 2.2 mumol/L respectively. The susceptibility pattern of EIAV RT to inhibitors was similar to that of HIV RT.

Antiviral Agents↗
PubMed1987

Diagnosis of tertian malaria by enzyme-linked immunosorbent assay.

A method of ELISA diagnosis of tertian malaria based on detecting Plasmodium vivax antigen in red blood cells (RBC) was developed, using 0.16 ml of packed, washed, and sonicated RBC. 68 blood samples from tertian malaria cases were examined; 67 (98.5%) were positive. 104 normal persons were all negative by this test. The lowest parasite number detected was 3 parasites/10(5) RBC on a thin film, or 1-2 parasites per thick film of usual size.

Animals↗