Biomedical subjects

Shuwen Liu

Publications and source records attributed to Shuwen Liu.

27 records · Page 2Linked to original sources

PubMed2004

N-substituted pyrrole derivatives as novel human immunodeficiency virus type 1 entry inhibitors that interfere with the gp41 six-helix bundle formation and block virus fusion.

A recently approved peptidic human immunodeficiency virus type 1 (HIV-1) fusion inhibitor, T-20 (Fuzeon; Trimeris Inc.), has shown significant promise in clinical application for treating HIV-1-infected individuals who have failed to respond to the currently available antiretroviral drugs. However, T-20 must be injected twice daily and is too expensive. Therefore, it is essential to develop orally available small molecule HIV-1 fusion inhibitors. By screening a chemical library consisting of "drug-like" compounds, we identified two N-substituted pyrroles, designated NB-2 and NB-64, that inhibited HIV-1 replication at a low micromolar range. The absence of the COOH group in NB-2 and NB-64 resulted in a loss of anti-HIV-1 activity, suggesting that this acid group plays an important role in mediating the antiviral activity. NB-2 and NB-64 inhibited HIV-1 fusion and entry by interfering with the gp41 six-helix bundle formation and disrupting the alpha-helical conformation. They blocked a d-peptide binding to the hydrophobic pocket on surface of the gp41 internal trimeric coiled-coil domain. Computer-aided molecular docking analysis has shown that they fit inside the hydrophobic pocket and that their COOH group interacts with a positively charged residue (K574) around the pocket to form a salt bridge. These results suggest that NB-2 and NB-64 may bind to the gp41 hydrophobic pocket through hydrophobic and ionic interactions and block the formation of the fusion-active gp41 core, thereby inhibiting HIV-1-mediated membrane fusion and virus entry. Therefore, NB-2 and NB-64 can be used as lead compounds toward designing and developing more potent small molecule HIV-1 fusion inhibitors targeting gp41.

CD4 Antigens↗

PubMed2004

Mapping of antigenic sites on the nucleocapsid protein of the severe acute respiratory syndrome coronavirus.

Antigenic sites on the nucleocapsid (N) protein of severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) were mapped by Pepscan analysis with overlapping peptides that span the N protein sequence. Two major immunodominant epitopes located in the C-terminal region (amino acids [aa] 362 to 412) and middle region (aa 153 to 178) reacted with more than 75% of sera from SARS patients. Several minor immunodominant epitopes were reactive with about 50% of the SARS sera. Antisera from mice immunized with inactivated SARS-CoV recognized the two major immunodominant epitopes and one antigenic site located adjacent to the N-terminal region (aa 76 to 101), which did not react with the sera from SARS patients. Several monoclonal antibodies against SARS-CoV bound to the N- or C-terminal antigenic sites. These results suggest that the above antigenic sites on the N protein are important in eliciting humoral immune response against SARS-CoV in humans and animals and can be used as antigens for developing diagnostic tests.

Amino Acid Sequence↗

PubMed2004

High throughput screening and characterization of HIV-1 entry inhibitors targeting gp41: theories and techniques.

The gp41 subunit of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein plays an important role in HIV-1 entry and severs as an attractive target for development of HIV-1 entry inhibitors, a new class of anti-HIV drugs. Triggered by gp120 binding to CD4 and a coreceptor, gp41 undergoes a conformation shift from a native prefusogenic state to a fusogenic state, in which the N-terminal heptad repeat (NHR) and C-terminal heptad repeat (CHR) associate to form a six-helix bundle, representing the fusion-active gp41 core. Any compound that disrupts the gp41 six-helix bundle formation may inhibit the gp41-mediated membrane fusion, thereby blocking HIV-1 entry into target cells. Peptides derived from the gp41 NHR and CHR regions, designated N- and C-peptides, can interact with the counterpart regions in gp41 and interfere with the six-helix bundle formation between the viral NHR and CHR region, thus inhibiting fusion of the virus with the target cell. One of the C-peptides, T-20 (brand name: Fuzeon), was recently approved by the US FDA as the first HIV entry inhibitor which can be used for treatment of AIDS patients who fail to respond to the current antiretroviral drugs, e.g., the reverse transcriptase inhibitors and protease inhibitors. The limitations of T-20 include lack of oral availability and high cost of production. Thus it is essential to develop small molecule HIV-1 entry inhibitors targeting gp41. This review summarizes the newly developed techniques for high throughput screening (HTS) and characterization of the HIV-1 entry inhibitors targeting gp41. The theories behind these techniques are also discussed. It is expected that the "drug-like" compounds with potent HIV-1 fusion inhibitory activity will be identified in the near future and used as leads for development of the low molecular weight HIV-1 entry inhibitors for the chemotherapy of HIV-1 infection and AIDS.

Animals↗

PubMed2003

Determination of the HIV-1 gp41 fusogenic core conformation modeled by synthetic peptides: applicable for identification of HIV-1 fusion inhibitors.

Triggered by receptor binding of gp120, the human immunodeficiency virus type 1 (HIV-1) gp41 changes its conformation to a fusogenic six-helix bundle structure. In the present study, this core conformation modeled by the peptides derived from the gp41 N- and C-terminal heptad repeat regions was determined by fluorescence native polyacrylamide gel electrophoresis and size exclusion high-performance liquid chromatography (HPLC). Two previously described small molecule HIV-1 fusion inhibitors significantly blocked the six-helix bundle formation. It suggests that these biophysical techniques can be used in a novel way to study the conformational change of gp41 during virus entry into cells and to identify HIV-1 fusion inhibitors.

Amino Acid Sequence↗

PubMed2003

Rapid and automated fluorescence-linked immunosorbent assay for high-throughput screening of HIV-1 fusion inhibitors targeting gp41.

The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp41 plays an important role in the virus entry. During the process of fusion between the viral and target cell membranes, the N- and C-terminal heptad repeat (HR) regions of the gp41 extracellular domain associate to form a 6-helical bundle, corresponding to the fusion-active gp41 core. Any compound that blocks the gp41 6-helix bundle formation between the N- and C-peptides, which are derived from the N- and C-terminal HR regions, respectively, may inhibit HIV-1 mediated membrane fusion. Based on this principle, we previously established a sandwich enzyme-linked immunosorbent assay (ELISA) for drug screening by using the N-peptide N36 and the C-peptide C34 and a monoclonal antibody (NC-1) which specifically recognizes the gp41 6-helix bundle. In the present study, a fluorescence-linked immunosorbent assay (FLISA) was developed by using fluorescein isothiocyanate (FITC)-conjugated C34 to replace C34 and by directly detecting fluorescence intensity instead of more complicated enzymatic reaction. Compared with the sandwich ELISA, this FLISA has similar sensitivity and specificity, but it is much more rapid, economic and convenient. Using an Integrated Robotic Sample Processing System, this assay has been applied for high-throughput screening of organic compounds on a large scale for HIV-1 fusion inhibitors targeting gp41.

Drug Evaluation, Preclinical↗

PubMed2003

[Study of diopters-cutting in treatment of PRK for myopia].

PURPOSE: To study a method of determining the diopters-cutting for photorefractive keratectomy (PRK) pre-operation. METHODS: By statistics, to analyze the differences of diopter between optometry of mydriasis and keratectomy in 143 cases 209 eyes of medium myopia with complete data recorded. RESULT: The average diopter for optometry of mydriasis is -4.32 D, for keratectomy, -4.74 D. The average of differences is (0.42 +/- 0.173) D, P < 0.01. CONCLUSION: The numerical value of diopter-cutting for operation should be higher than for optometry of mydriasis in treatment of PRK for myopia.

Adolescent↗

PubMed2002

Identification of inhibitors of the HIV-1 gp41 six-helix bundle formation from extracts of Chinese medicinal herbs Prunella vulgaris and Rhizoma cibotte.

An increasing portion of patients with HIV infection and/or AIDS cannot use currently FDA-approved anti-HIV drugs, including the reverse transcriptase and protease inhibitors, due to the adverse effects and the emergence of drug resistance. Thus, it is essential to develop new anti-HIV agents with a target different from the HIV reverse transcriptase and protease. Using a conformation-specific monoclonal antibody NC-1, we previously established a high throughput screening assay for identification of small molecular organic compounds that disrupt the HIV-1 gp41 six-helix bundle formation, a critical step of membrane fusion between the HIV and the target cell. In the present study, we used this assay to screen for inhibitors of the gp41 six-helix bundle formation from aqueous extracts of nine Chinese medicinal herbs with antiviral activity. We found that the extracts of two herbs, Prunella vulgaris and Rhizoma cibotte, showed potent inhibitory activity. The inhibitory activity of these two herb extracts significantly decreased after they were passed through polyamide resin mini-columns, which are able to bind polyphenols including tannin, an HIV-1 inhibitor with multiple mechanisms of action. The bound polyphenols were eluted from the polyamide columns and also showed potent inhibitory activity on the gp41 six-helix bundle formation. Tannin purchased from different commercial sources inhibited the gp41 six-helix bundle formation in a manner similar to the polyphenols isolated from the herb extracts. These results suggest that tannin may be one of major inhibitors of the HIV-1 gp41 six-helix bundle formation in the herb extracts and that tannin may inhibit HIV-1 entry by disrupting the gp41 six-helix bundle formation.

Antibody Specificity↗

PubMed2002

[A randomized control trial of mycophenolate mofeil treatment in severe IgA nephropathy].

OBJECTIVE: To investigate the effectiveness safety and tolerance of mycophenolate mofeil(MMF) in severe IgA nephropathy and evaluate the dosage adjustment and course for clinical treatment. METHODS: 62 patients with IgA nephropathy diagnosed by renal biopsy as Lee's grade IV and V with urinary protein > 2.0 g/d were enrolled randomly in the trial. The initial dosage of MMF was 1.0 g/d (body weight < 50 kg) or 1.5 g/d (body weight > 50 kg). The dosage was reduced to 0.75 approximately 1.0 g/d after 6 months treatment, the maintaining dosage was 0.5 approximately 0.75 g/d after 12 months. The total course of treatment lasted at least 12 months. Another 31 patients matched with age gender and severity of renal damage were given prednisone orally (0.8mg(;)kg(;)d) (control group).Blood and urinary tests hepatic and renal function plasma albumin serum triglyceride and cholesterol 24 h protein excretion urinary NAG enzyme, creatinine clearance(Ccr) were performed before and 3 6 12 18 months after treatments in both groups 5 patients in MMF group received repeated renal biopsy. RESULTS: (1) After 3 months treatment, decrease of urinary protein (1.9 g/24 h +/- 1.6 g/24 h vs 3.2 g/24 h +/- 1.7 g/24 h, P < 0.01) and improvement of plasma albumin (41 g/L +/- 6 g/L vs 37 g/L +/- 6 g/L, P < 0.01) were observed in MMF groups while in control group, no significant changes were found in uinary protein (2.3 g/24 h +/- 1.8 g/24 h vs 2.9 g/24 h +/- 1.5 g/24 h, P < 0.05) and plasma albumin (40 g/L +/- 6 g/L vs 37 g/L +/- 6 g/L, P < 0.05). After treatment for 6, 12 and 18 months, both group showed obvious alleviation of proteinuria and albumin. At the 12th and 18th month, the proteinuria in MMF group was significantly improved than that in control group (0.8 g/24 h +/- 0.8 g/24 h vs 1.4 g/24 h +/- 1.6 g/24 h and 0.6 g/24 h +/- 0.7 g/24 h vs 1.4 g/24 h +/- 1.3 g/24 h, P < 0.05 respectively). The remission rate and total effective rate of MMF group were higher than those of the control group (44.4% vs 19.1% and 88.9% vs 61.9%, P < 0.05 respectively). Patients were administered with MMF for 13.8 +/- 6.3 months (6 approximately 30 m). (2) Serum cholesterol and triglyceride were remarkably reduced after 6,12 and 18 months treatment in MMF group, no significant difference was found in control group(P < 0.05). (3) For the 6 patients with renal insufficiency in MMF group, MMF treatment was significantly effective in 1 patient, effective in 2 patients, not effective in 3 patients with an overall effective rate of 50%. For the 7 patients with renal insufficiency in control group, the treatment was significantly effective in 1 patient, effective in 1 patient, not effective in 5 patients and total effective rate is 28.6%. (4) 5 patients in MMF group received repeated renal biopsy after 7 approximately 12 months treatment (mean 9.8 +/- 2.3 m). The results showed that the interstitial lesions were alleviated. No special drug-induced renal damage was obtained. (5) Side effects: 3 patients in MMF group suffered from slight diarrhea, 1 patient herpes zoster, all of them got remission without drug withdrawal. 1 patient suffered nausea in the first weeks. No significant change was found in hepatic function (P > 0.05). CONCLUSIONS: MMF is more effective in reducing proteinuria and serum lipid than the currently widespread use of prednisone therapy in IgA nephropathy patients with Lee SMK's grade IV approximately V and urinary protein > 2.0 g/d. Treatment with MMF associates with less adverse effect and good tolerance.

Adolescent↗

PubMed2002

[The effects of angiotensin-converting enzyme inhibitor on IgA nephropathy and the influencing factors].

OBJECTIVE To investigate the effects of angiotensin-converting enzyme inhibitor (ACEI) on IgA nephropathy(IgAN) and the factors influencing the therapeutic effects. METHODS 131 cases with IgAN diagnosed by renal biopsy were randomly divided into two groups: ACEI group (benazepril 10 mg/d) and non-ACEI group as control. The pathological changes in the kidney were analyzed using Lee SMK. RESULTS After 1 month treatment of ACEI, the levels of proteinuria and serum cholesterol decreased significantly, meanwhile those of serum albumin and total protein increased obviously in patients with IgAN(P < 0.05). The proteinuria level at the 3rd month after treatment was lower than that at the 1st month, but was same as that at the 18th month. While in the control group the proteinuria level increased and the clearance of creatinine decreased continuously during the observation (P < 0.05). The effects correlated positively with mesangial proliferation and negatively with course of the disease glomerular sclerosis in glomerulus and changes of small arterioles in the kidney. Normal blood pressare normal renal function I approximately II degree of Lee SMK I degee of interstitial changes minimal changes of small arterioles and mild glomerular sclerosis predicted better response to ACEI treatment than hypertension renal insufficiency V degree of Lee SMK IV degee of interstitial changes severe changes of small arterioles and massive glomerular sclerosis. CONCLUSIONS It is suggested that benezepril could definitely reduce the excretion of urinary protein and protect renal function of patients with IgAN and should be used as earlier as possible. Mesangial prolife ration glomerular sclerosis in glomerulus changes of small arterioles in kidney and course of the disease are the major influencing factors of ACEI treatment on IgAN.

Adolescent↗