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Biomedical subjects

W T Liu

Publications and source records attributed to W T Liu.

At least 73 records · Page 4Linked to original sources
PubMed1994

Solution conformation of enopeptin A, a depsipeptide antibiotic, using 2D NMR and restrained molecular dynamics studies.

Studies on the solution conformation of the cyclic depsipeptide antibiotic enopeptin A have been carried out using 2D NMR and molecular modelling techniques. The proton resonances of the antibiotic in DMSO-d6 have been assigned by the use of TOCSY and ROESY experiments. The interproton distance information obtained from the ROESY experiments have been used as the basis for elucidating the probable structures in solution. The restrained molecular dynamics technique was applied to calculate the structures in solution, and six resultant structures with fewer distance constraint violations were obtained that satisfy the experimental restraints very well. The conformation of the cyclic moiety of the molecules is well defined whereas the aliphatic chain segment is disordered.

Amino Acid Sequence↗
PubMed1993

Herpes simplex virus type 1 genes in human mononuclear cells and affecting cell-mediated immunity.

To evaluate whether herpes simplex virus type 1 (HSV-1) replicates in freshly isolated human mononuclear cells (HMNC) and results in cell-mediated immunity, HMNC purified from the peripheral blood of a healthy HSV-1-seronegative individual were infected with HSV-1 (KOS strain). The kinetic data indicated that HSV-1 particles were detected in HMNC at 9 hr postinfection, and the highest HSV-1 titer was obtained at 24 hr postinfection. It was found that the newly synthesized HSV-1 DNA increased in HMNC corresponding to the duration of time postinfection. The HSV-1 tk mRNA was detected in HSV-1-infected HMNC by Northern blot analysis. The Western blot analysis indicated that the HSV-1-infected HMNC could express the viral proteins. These results suggest that HSV-1 replicates in freshly isolated HMNC and expresses its DNA, RNA, and proteins. Interleukin-2 (IL-2) production and cell-mediated cytotoxicity (CMC) were also determined in HSV-1-infected HMNC but were lower than those found in uninfected HMNC. On the other hand, HSV-1 DNA was detectable in HMNC of patients suffering from recurrent HSV-1 infection. The results show that, in the recrudescent phase, the patients' HMNC contain more HSV-1 DNA than in the convalescent phase. We conclude that the impairments of immune responses are related to the infection of HMNC by HSV-1.

Adolescent↗
PubMed1993

Nutritional status of Chinese-, Korean-, and Japanese-American elderly.

OBJECTIVE: To examine the nutritional status of three major subgroups of Asian-American elderly. SUBJECTS: The sample consisted of 169 Chinese, 90 Korean, and 50 Japanese elderly who lived in five apartment buildings for senior citizens in Chicago, Ill. MAIN OUTCOME MEASURES: Twenty-four-hour dietary recalls were used to evaluate dietary intake. Anthropometric measures of height, weight, and triceps skinfold thickness were also obtained. RESULTS: Many Asian-American elderly consume an inadequate amount of dietary calcium. A large percentage of Korean elderly also consume inadequate amounts of protein and vitamins A and C. Underweight was more common than obesity among these ethnic elderly groups. APPLICATIONS: The information in this article provides valuable data to the Asian-American community for program planning as well as to health providers who work with individual Asian-American elderly to meet their nutrition needs.

Aged↗
PubMed1993

Functional status, education, and the diagnosis of dementia in the Shanghai survey.

We examined the relationship of culturally adapted Chinese versions of the Mini-Mental State Examination (CMMS) and several functional measures to the effect of education on the clinical diagnosis of dementia in 554 subjects (55 to 95 years; median, 74) who had undergone intensive evaluation during the Shanghai survey of dementia. Low education was associated with increased prevalence of clinically diagnosed dementia. The standardized history and one functional scale (Pfeffer Outpatient Disability Scale [POD]) clustered closely with clinical diagnosis on factor analysis, whereas the CMMS, Instrumental Activities of Daily Living scale (IADL), and Activities of Daily Living scale (ADL) loaded additionally onto an education-weighted component. A logistic equation based on the CMMS, history, POD, and IADL was the best predictor of the clinical diagnosis of dementia, but history, POD, and IADL without a mental status score also predicted the diagnosis with a sensitivity of 88.6%, a specificity of 89.3%, a positive predictive value of 66.0%, and a negative predictive value of 97.1%. When dementia was diagnosed using an algorithm based on the three functional scales alone, low education continued to be associated with increased age-specific risk of dementia.

Activities of Daily Living↗
PubMed1993

The need for second-generation antihepatitis C virus testing in uremic patients on continuous ambulatory peritoneal dialysis.

OBJECTIVE: To assess the prevalence and clinical relevance of a hepatitis C virus (HCV) infection in continuous ambulatory peritoneal dialysis (CAPD) patients by first- (Ortho) and second-generation (Abbott and UBI) HCV antibody enzyme immunoassays. DESIGN: Thirty-two serum samples tested by first-generation HCV antibody enzyme immunoassays (EIA's) were reevaluated using two second-generation HCV antibody EIA's. Basic demographic data, history of blood transfusions, and duration of hemodialysis and CAPD were reviewed. Results were analyzed by chi square analysis, Wilcoxon rank sum, and the paired t-test. SETTING: The medical college's affiliated teaching hospital. RESULTS: The prevalence of the antibody anti-HCV increases with the duration of previous hemodialysis, but not with the duration of CAPD. The positive detection of anti-HCV by second-generation HCV antibody EIA's was higher than first-generation EIA's (25% and 34.4% vs 12.5%). CONCLUSION: The prevalence and clinical relevance of HCV infection can be more accurately studied using the second-generation assays in uremic patients.

Adolescent↗
PubMed1993

A new influenza virus A/H3N2 variant of Taiwan origin.

A clinical isolate of influenza virus A/H3N2 from a one-year-old boy with pharyngitis was examined by using RNA-polymerase chain reaction (PCR) for amplification of viral cDNA and subsequent DNA sequencing with asymmetric PCR. Since antigenic drift has been found in recent A/H3N2 isolates, this strain was compared with A/Shanghai/24/90 and other A/H3N2 strains, collected at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA, USA. It was found that the steady changes of amino acid at location 190 and 262 of HA1 region were very similar to some recent isolates. This 1989 isolate may be the origin of a new influenza virus A/H3N2 variant.

Amino Acid Sequence↗
PubMed1993

Prognostic significance of human papillomavirus detected with polymerase chain reaction in cervical cancer.

In order to investigate the prognostic factors of cervical cancer and its association with human papillomavirus (HPV), we analyzed 50 specimens of cervical cancer with a DNA polymerase chain reaction (PCR) mainly to detect HPV types 16 (HPV 16) and 18 (HPV 18). The result showed that at least 74% (37/50) of the specimens had HPV DNA. Among them, 54% (20/37) of the cases were HPV 16 and 32% (12/37) were HPV 18. These HPV DNA positive patients had poorer differentiation in histology than the HPV DNA negative patients. We draw no conclusion about the prognostic significance of HPV DNA in cervical cancer. Perhaps more cases should be analyzed.

Adult↗
PubMed1993

Five-year experience of human immunodeficiency virus type 1 national screening program implemented at Veterans General Hospital-Taipei.

From July 1986 through June 1990, 33,199 sera from various risk groups were collected in Veterans General Hospital-Taipei for detection of antibody against human immunodeficiency virus, type 1 (HIV-1). Sixty-five samples were proved positive by Western blot analysis. Among individual high risk groups, hemophiliacs had the highest positive rate of 20/60 (29.41%), followed by homosexual/bisexual males (41/1,264, 3.24%). The overall positive rate was 65/33,199 (0.19%). Ten cases were recognized as acquired immunodeficiency syndrome (AIDS), 1 case had AIDS-related complex (ARC) and 4 case had other apparently symptomatic infections. Among these 15 cases, 7 expired, 1 lost of follow-up and 7 surviving cases are being treated with zidovudine (AZT). Most of symptomatic HIV-1 antibody positive cases had abnormal T4/T8 ratio of 0.39 +/- 0.54 as compared with the asymptomatic HIV-1 carriers at a ratio of 0.81 +/- 0.69. The opportunistic infections included Pneumocystis carinii pneumonia (PCP) in 6 case, disseminated cytomegalovirus infection in 6 cases, herpes zoster virus infection in 3 case, candidiasis in 4 cases, syphilis in 3 cases, pulmonary tuberculosis in 2 cases, and others with cryptococcosis, salmonellosis, Mycobacterium avium-intracellulare infection, gonorrhea, Staphylococcus aureus endocarditis and bacterial sepsis, etc. The natural history of HIV-1 infection to AIDS involved acute and persistent multiple infections. Although prevalence of HIV-1 infection was low in Taiwan, nationwide surveillance of HIV-1 infection in various risk groups is still needed.

AIDS-Related Opportunistic Infections↗
PubMed1992

Virus-like particles with reverse transcriptase activity associated with Kawasaki disease.

To investigate the etiologic agent associated with Kawasaki disease (KD), we initially established a cocultivation system using concanavalin A (Con A)-stimulated lymphoblastoid cells obtained from each retrovirus-seronegative individual's peripheral blood mononuclear cells (MNCs) cocultivated with each of 1) 40 patients with KD, 2) 10 patients with other viral infection and skin rash, and 3) 10 age- and sex-matched normal controls. Five major findings suggested that virus-like particles with reverse transcriptase (RT) activity are associated with KD. First, RT activity appeared significantly higher on day 12 after the onset of fever in the KD patients than in those with other viral infections and normal controls (dTMP incorporation: 3,645 +/- 248 vs. 434 +/- 50 vs. 412 +/- 46 cpm, P < 0.0001). Second, the RT activity was not endogenous, because the Con A-stimulated lymphoblastoid cells were obtained from the individuals who were negative for retrovirus. Third, virus-like particles (80-100 nm in diameter) by electron microscopy were found in the concentrated pool supernatants of particulate fraction containing RT activity subjected to sucrose density gradient, obtained from KD patients. Fourth, the viral product, a 31.4 kilodalton molecule, was detected by SDS-PAGE after internal labelling (methionine-S35) and density gradient centrifugation. Fifth, using a "retrovirus universal pol gene region" as a primer and the RT-PCR method, a retrovirus-specific band was detected in the cocultivated supernatants obtained from four KD and one AIDS patients but not in patients with rubella or in healthy controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1992

Suppression of human interferon-gamma production by a 17 amino acid peptide homologous to the transmembrane envelope protein of retroviruses: evidence for a primary role played by monocytes.

CKS-17, a synthetic amino acid peptide homologous to a highly conserved region of retroviral transmembrane protein exerts a suppressive action on staphylococcal enterotoxin A (SEA)-induced the production of IFN-gamma by human peripheral blood mononuclear cells (PBMC) (Ogasawara et al., J. Immunol. 141, 615, 1988). This action has been shown in the present study to be preceded by dramatic clustering of PBMC. Clusters appear within 3 hr of exposure of PBMC to CKS-17; they are dose dependent, inhibited by cycloheximide, and require a temperature of 37 degrees C. The cells in the clusters are predominantly monocytes. Although it has been previously shown that CKS-17 inhibits monocyte-mediated killing by inactivating IL-1 (Kleinerman et al., J. Immunol. 139, 2329, 1987) and production of IL-2 by murine thymoma cells treated with IL-1 (Gottlieb et al., J. Immunol. 142, 4321, 1989), in the present study we show that IL-1 does not prevent clustering of PBMC by CKS-17. Using CKS-17 and highly purified monocytes or lymphocytes, profound alterations occur only with monocytes, as revealed by light or electron microscopy. SEA- or staphylococcal enterotoxin B-induced production of IFN-gamma is inhibited when highly purified monocytes pretreated with CKS-17 are cocultured with highly purified T lymphocytes. Thus, CKS-17 induces dramatic clustering of cells apparently by inducing alterations of monocytes but not lymphocytes, suggesting that CKS-17 may interfere with the capacity of monocytes to facilitate production of IFN-gamma by T lymphocytes.

Amino Acid Sequence↗
PubMed1992

Inhibition of astrocyte proliferation and binding to brain tissue of anticardiolipin antibodies purified from lupus serum.

Polyclonal anticardiolipin antibodies purified from pooled serum samples of patients with systemic lupus erythematosus were shown to have inhibitory effects on cultured normal rat brain astrocytes (RBA-1 cells). Anticardiolipin antibodies at concentrations from 50 to 200 micrograms/ml inhibited the [3H]thymidine incorporation of RBA-1 cells in a dose dependent manner after three days of culture. A kinetic study showed that anticardiolipin antibodies (100 micrograms/ml) maximally inhibit the proliferation of RBA-1 cells (20.6 (5.1)% of the control value) after incubation for one day. In contrast, human gamma globulin (100 micrograms/ml) had no effect on these cells. In the presence of anticardiolipin antibodies (100 micrograms/ml), the RBA-1 cells attached to the bottom of wells became spherical and the expression of glial fibrillary acidic protein in the cytoplasm was slightly reduced. Using 3,3'-dihexyloxacarbocyanine iodide as an indicator, anticardiolipin antibodies depolarised the membrane potential of RBA-1 cells after one day of culture. In addition, the percentage binding of RBA-1 cells with anticardiolipin antibodies was greater than with gamma globulin as determined by flow cytometric analysis. Immunofluorescence staining of brain tissue from BALB/c mice with anticardiolipin antibodies was noted in the corpus callosum, the cellular zone near the corpus callosum, and cells scattered in brain tissue. These results suggest that anticardiolipin antibodies have an inhibitory effect on brain cells and elicit thrombus formation in brain vessels, which plays a part in neuropsychiatric lupus.

Animals↗
PubMed1992

US National Health Data on Asian Americans and Pacific Islanders: a research agenda for the 1990s.

OBJECTIVES: In spite of over 30 years of periodic nationwide surveys, we have thus far only the most rudimentary estimates of the determinants of the health of Asian Americans and Pacific Islanders. This paper explores ways to improve the capability of the National Center for Health Statistics (NCHS) to collect national health data on these populations. METHODS: The NCHS "race" coding practices are reviewed, their limitations stated, ways to improve the numerator and denominator data discussed, and a research agenda presented. RESULTS: Resources can be intensified to produce better denominator data, and to improve the collection of detailed ethnicity information for the numerators, in at least the three states (California, New York, and Hawaii) where the majority of Asian/Pacific Islanders lived in 1990. Subsequently, these efforts should be extended to the 10 states where 79% of these individuals reside or to the top 15 metropolitan areas where they are concentrated. CONCLUSIONS: If the recommendations are implemented, several coordinated multisite, multiwave epidemiologic surveys can be conducted using standardized interview instruments and data collection procedures that will capitalize on the geographic distribution of Asian/Pacific Islanders.

Abstracting and Indexing↗
PubMed1992

Evaluation of anti-HTLV-1 in physical-checkup individuals and blood donors in Taiwan.

The gelatin particle agglutination (GPA) test specific for antibody detection of human T-cell lymphotropic virus type 1 (HTLV-1) was used to screen 500 blood donors and 5000 physical-checkup individuals at Veterans General Hospital-Taipei. The positive rate of physical-checkup individuals and the blood donors was 0.18% (9/5000) and 0% (0/5000) respectively. Among the 9 GPA positive specimens, eight were confirmed to be positive by western blot analysis and a prevalence rate of 0.16% (8/5000). Seven of the nine GPA positive samples were also positive by indirect fluorescent antibody test and two of them had indeterminate results. Since GPA is less expensive, relatively simple and convenient, we recommend that GPA could be used as screening test for HTLV-1 infection of blood donors, followed by western blot method as a confirmatory test in blood bank.

Adolescent↗
PubMed1991

Regulation of cellular trans-activating activities in two different promonocytic leukemia cell lines.

Trans-activating activities of certain cellular promoter/enhancer genes may reflect the underlying mechanism for cellular differentiation. We have used two promonocytic leukemia cell lines, U937 and HL-CZ, which differ in their differentiation antigen expression. While both cell lines express CD15 antigen, only the former expresses both CD4 and CD10 antigens. These phenotypes suggest that these two cell lines appear to be arrested at different stages of differentiation. Some regions of the long terminal repeat (LTR) of human immunodeficiency virus-1 (HIV-1) contain nucleotide sequences which bind cellular trans-activating factors such as NF-kappa B and Sp1. These sequences are also present in cellular regulatory gene sequences. The cell lines have been transfected by electroporation with a nested series of deletion mutants containing different lengths of the promoter/enhancer region for HIV-LTR. The promoter/enhancer region has been linked to a 'reporter' chloramphenicol acetyl transferase (CAT) gene. We have found that promoter/enhancer trans-activation is markedly enhanced by treating transfected cells with 12-O-tetradecanoylphorbol-13-acetate (TPA), while similar treatment with tumor necrosis factor-alpha (TNF alpha) slightly enhanced activation. U937 cells always showed much greater transactivating activities than did HL-CZ cells. Deletion of a negative regulatory element (NRE) from the LTR resulted in an enhanced transactivation, while deletions affecting NF-kappa B and/or Sp1 binding sites markedly reduced transactivation. Deletion of both NRE and NRF, a second negative regulatory factor binding site, from the LTR restored the transactivation. However, in the presence of TPA, deletion of NRE sequence without concomitant deletion of the downstream NRF binding sequence was sufficient for recovering transactivation. Since these two cell lines have shown subtle differences in these responses, it may be speculated that monocytes at different stages of differentiation may respond in different ways, qualitatively and/or quantitatively, to signal transduction factors involved in the transactivation of cellular genes.

Antigens, Differentiation↗
PubMed1991

Isolation of dengue virus with a human promonocyte cell line.

In October-November, 1988 there was an outbreak of dengue fever in the Kaoshiung area of southern Taiwan. We collected 100 serum samples from 96 patients at the onset of their fever for virus cultures and identification. A human promonocyte cell line (HL-CZ) established in our laboratory was used and proved to be susceptible for dengue virus propagation. Type 1 dengue virus in the HL-CZ cell culture was identified by immunofluorescence tests using monoclonal antibodies, and also by hemagglutination tests with goose red blood cells. The density of the virus particles, as measured by sucrose gradient ultracentrifugation, ranged from 1.186 to 1.224 g/ml. The virus yield from this cell culture is comparable with that from the C6/36 mosquito cell line. There was a significant correlation between the antibody responses tested with Western dot blots and hemagglutination inhibition techniques.

Adolescent↗
PubMed1991

Prevalence of antibodies to hepatitis C virus (anti-HCV) in different populations in Taiwan.

The prevalence of antibodies to hepatitis C virus (anti-HCV) was investigated among different populations in Taiwan, where anti-HCV was detected in 0.8% (24/2,994) of adult volunteer blood donors, 0.1% (1/1,305) of youngsters and children, 12.5% (8/64) of adult volunteer blood donors with elevated alanine aminotransferase (ALT), 36.5% (23/63) of hemodialysis patients, 4.1% (13/318) of male homosexuals, 25.4% (16/63) of cases positive for antibodies to human immunodeficiency virus (anti-HIV), 82.2% (578/703) of intravenous drug users (IVDUs), and 10.3% (23/223) of female prostitutes (FPs). Among patients with chronic liver diseases including chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC), the overall prevalence rate for anti-HCV was 34.1% (42/123), and a higher prevalence was noted in hepatitis B surface antigen (HBsAg)-negative cases than in HBsAg-positive cases. The prevalence of anti-HCV in volunteer blood donors and high prevalence found in IVDUs, hemodialysis patients, anti-HIV positive cases, and FPs are consistent with those results from other countries. These findings suggest that hepatitis C virus (HCV) infection is transmitted by both blood-borne and sexual contact routes. Among flavivirus infections, anti-HCV was detected in 0.3% (1/289) and 1.3% (4/310) of Japanese encephalitis and dengue fever patients, respectively. In conclusion, in Taiwan, an area with high endemicity of hepatitis B virus (HBV) infection, the epidemiological status of HCV infection is similar to that observed in other countries, and no serum cross-reactivity was noticed between HCV and flavivirus infections.

Adolescent↗
PubMed1991

Withdrawal of immunosuppressive therapy in allogeneic bone marrow transplantation reactivates chronic viral hepatitis C.

A 28-year-old female patient with acute myelogenous leukemia and post-transfusion chronic viral hepatitis C received an allogeneic bone marrow transplantation (BMT) in first complete remission. The inflammatory activity of chronic hepatitis C decreased dramatically with the start of BMT and during the whole course of cyclosporin A treatment. After the immunosuppressive therapy was stopped, however, the chronic hepatitis C activity increased and the serum alanine amino-transferase levels thereafter remained as high as before BMT. Hepatitis C virus RNA was detected by polymerase chain reaction in serum drawn 60 days and 52 months after BMT. Since fulminant viral hepatitis B may take place after tapering of immunosuppressive therapy following BMT due to an excessive response of recovering immunity to the actively replicating virus during immune suppression, careful monitoring of liver function for patients with chronic viral hepatitis C in BMT is suggested.

Adult↗