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C T Fang

Publications and source records attributed to C T Fang.

At least 55 records · Page 3Linked to original sources
PubMed1991

Serological discrimination between HTLV-I and HTLV-II antibodies by ELISA using synthetic peptides as antigens.

Using the peptides from amino acids 100-130 of the HTLV-I gag protein, 175-199 of the HTLV-I env protein and the corresponding peptides of HTLV-II (amino acids 106 to 135 of the gag protein and 171 to 196 of the env protein), we tested for reactivity against antibodies by enzyme immunoassay in sera from HTLV-I and HTLV-II carriers. The peptides derived from the env proteins have high specificity for antibody binding. The peptide based on amino acids 175-199 of HTLV-I reacted with antibodies in sera from all HTLV-I carriers, and the peptide composed of amino acids 171-196 of HTLV-II reacted with antibodies in sera from all HTLV-II carriers. For the peptides derived from the gag proteins, we observed some cross-reactivity in sera from persons with anti-HTLV-I and anti-HTLV-II, due to antibody binding to the peptide corresponding to 12 amino acids from the C-terminal end of the gag protein. Separate enzyme immunoassays that used the four synthetic peptides as antigens clearly distinguished between serum with antibodies to HTLV-I or HTLV-II in various individuals and excluded false positive results using the particle agglutination assay that used a whole-virus lysate of HTLV-I as antigen.

Amino Acid Sequence↗
PubMed1991

Relative prevalence and risk factors of HTLV-I and HTLV-II infection in US blood donors.

The clinical significance of human T-cell lymphotropic virus type II (HTLV-II) infection, unlike that of HTLV-I, is unknown, and the major known association of HTLV-II seropositivity is with intravenous drug abuse. Screening of blood donors for HTLV-I, now routine in North America, does not distinguish this retrovirus from HTLV-II. To find out more about the seroepidemiology of and risk factors for HTLV I and II, blood from 480,000 volunteer donors in five geographically separate US urban centres was tested for antibodies to HTLV-I/II and HIV-1. Confirmed HTLV-I/II seropositive donors were then followed up by DNA amplification to distinguish type I from type II and by interviews focusing on possible risk factors. HTLV seroprevalence was 3.3 times greater than that for HIV-1 (0.043% vs 0.013%). DNA amplification on 65 of the 207 HTLV-I/II seropositive donors revealed that 34 (52%) had HTLV-II infection and 28 (43% had HTLV-I; 3 samples were uninformative. Interviews of 49 donors showed that whereas HTLV-I was principally associated with donor origin from endemic regions, the major risk factor for HTLV-II infection was intravenous drug use. The surprisingly high rate of HTLV-II infection in US blood donors raises important public health and donor counselling issues since HTLV-I infection is associated with adult T-cell leukaemia and a neurological disorder while the pathogenicity of HTLV-II is as yet unclear.

Adult↗
PubMed1991

Improved serodiagnosis of hepatitis C virus infection with synthetic peptide antigen from capsid protein.

Cloning and expression of hepatitis C virus have allowed the development of immunoassays to detect hepatitis C virus infection. However, currently available recombinant fusion protein C100-3 assays, based on a nonstructural protein of the virus, are limited in sensitivity, particularly for detecting acute infection. In this report seroconversion panels showed that an assay based on synthetic peptides, derived from immunodominant regions of both capsid and nonstructural proteins, accelerated hepatitis C virus antibody detection by 4-10 weeks. In screening, this enzyme immunoassay increased detection from 47% to 64% in plasmapheresis donors with elevated alanine aminotransferase levels (greater than 100 international units per liter), from 15% to 24% in anti-hepatitis B core antigen-positive blood donors, and from 28% to 42% in renal dialysis patients when compared with nonstructural peptide-based assays. The screening assay was repeatedly reactive for 27 of 2902 volunteer blood donor samples (0.93%); four sera reacted only with the capsid antigen. The peptide test distinguished true from false positive results in agreement with recombinant immunoblot assay in 96% of blood donor samples repeatably reactive on a recombinant hepatitis C virus enzyme immunoassay.

Animals↗
PubMed1991

Human T-cell lymphotropic virus type I and II in transfusion medicine.

As a consequence of migrating populations, IV drug use and, to a lesser extent, blood transfusions, endemic HTLV-I and HTLV-II infections have spread to nonendemic geographic regions. Although the risk that a person infected with HTLV-I will develop significant disease--even over a lifetime--is estimated to be relatively low, our awareness of the serious diseases associated with other retroviruses requires a cautious approach to blood transfusion. Reports from Japan and the United States indicate that programs testing donated blood and excluding units with HTLV-I antibodies have been highly successful in interrupting the spread of HTLV-I by transfusions. One unanticipated outcome of testing large numbers of people in the United States for HTLV-I antibodies has been recognition of the relatively high prevalence of HTLV-II infection, particularly among IV drug users. The long-term effects of HTLV-II infection are also unknown. Until the natural history and clinical consequences of HTLV-II infection are clearly understood, it is only prudent that blood donated by persons identified to be HTLV-II carriers also be excluded.

Blood Banks↗
PubMed1991

Antibodies to hepatitis C virus in autologous blood donors.

Hepatitis C virus (HCV) is the major cause of posttransfusion hepatitis. Two anti-HCV enzyme immunoassay (EIA) kits and one recombinant immunoblot assay (RIBA) were used to test serum samples of 1476 donations from 692 autologous blood donors to assess the prevalence of anti-HCV and its relationship to transfusion history. Of all autologous blood donations, 23 (1.6%) reacted when tested with one EIA kit and 29 (2.0%) reacted when tested by the other EIA kit. Of the autologous donors, 12 (1.78%) reacted by the first EIA kit and 14 (2.02%) by the second. Discrepancies in the EIA results from different donations by the same donor were seen in seven donors. The RIBA was positive or indeterminate in 33 percent of the EIA-reactive donations and in 41 percent of EIA-reactive donors. All RIBA-positive and -indeterminate samples reacted with both EIA kits. There was no significant difference in the EIA-reactive rates of autologous and first-time homologous blood donors. Previously transfused autologous blood donors had a higher anti-HCV EIA-reactive rate than nontransfused autologous donors, but the difference was not significant. In regard to hepatitis C, the use of autologous blood for homologous transfusion appears to be as safe as the use of blood from first-time homologous donors. Universal testing of previously transfused patients for hepatitis C appears premature at this time. Discrepant anti-HCV EIA results from different donations from the same individual have implications regarding donor deferral.

Adolescent↗
PubMed1991

Transmission of human T-lymphotropic virus types I and II by blood transfusion. A retrospective study of recipients of blood components (1983 through 1988). The American Red Cross HTLV-I/II Collaborative Study Group.

We studied results of a "lookback" program involving laboratory testing and interviews of 133 recipients of prior donations from blood donors seropositive for human T-lymphotropic virus types I and II (HTLV-I/II) identified at 28 American Red Cross blood centers. The study was designed to explore the natural course of posttransfusion HTLV-I/II infection among individuals who received blood components from donors subsequently identified as being HTLV-I/II seropositive. Seventeen recipients were seropositive, an apparent transmission rate of 12.8%. Red blood cells and platelets were the implicated components, and red blood cells that were less than 6 days old had a transmission efficiency of 80%. Virus typing enabled documentation of primary and secondary transfusion transmission of HTLV-I and HTLV-II, including the direct transmission of HTLV-II by a donor with a history of intravenous drug use. We conclude that transfusion transmission of HTLV-I/II to approximately 700 recipients per year occurred in the United States before routine donor testing began in 1988.

Adolescent↗
PubMed1990

The western immunoblot procedure for HIV antibodies and its interpretation.

The Western blot is frequently used to confirm human immunodeficiency virus type 1 (HIV-1) screening tests as it permits the identification of antibodies to individual component polypeptides of HIV-1. The procedure is described and different criteria for evaluation of HIV-1 Western blots are compared. The significance and management of indeterminate blot patterns are discussed.

Blotting, Western↗
PubMed1988

Seroprevalence and epidemiological correlates of HTLV-I infection in U.S. blood donors.

Screening for human T-lymphotropic virus type I (HTLV-I) antibodies was performed on sera from 39,898 blood donors at eight blood centers in geographically distinct areas of the United States. Ten donors (0.025 percent) showed evidence of HTLV-I seropositivity by enzyme immunoassays; this was confirmed by protein immunoblot and radioimmunoprecipitation. Seroprevalence rates ranged from 0 to 0.10 percent at the locations sampled, with HTLV-I antibodies found predominantly in donors from the southeastern and southwestern United States. Matched case-control interviews and laboratory studies were performed on five seropositive women and two seropositive men who participated in an identity-linked collection of sera from a subset of 33,893 donors at six of the eight blood centers. Four of the women and both men are black; one woman is Caucasian. Four of the seven seropositive individuals admitted to prior intravenous drug abuse or sexual contact with an intravenous drug user. Sexual contact with native inhabitants of an HTLV-I endemic area was the only identified risk factor for one male. The distribution of HTLV-I antibodies in this U.S. blood donor sample corroborates the previously reported epidemiology of this agent and suggests that additional donor screening measures, including the testing of donated blood for HTLV-I markers, may be necessary to prevent the spread of HTLV-I to transfusion recipients.

Adult↗
PubMed1987

An autopsy-proved case of AIDS in Taiwan.

The first case of AIDS positively identified in a non-foreigner in Taiwan was a 25-year-old unmarried male who had practiced homosexuality for ten years. The patient began to have abdominal pain accompanied with loose stools and weight loss in June 1985, followed by fever, cough, headache, dizziness, and loss of memory. Facial hyperpigmentation and extensive oroesophageal candidiasis were noted. Laboratory studies showed severe lymphopenia with a reversed T-helper to T-suppressor ratio, cutaneous anergy and polyclonal gammopathy. Human immunodeficiency virus (HIV) antibodies were positive by ELISA and Western blot, and the virus was isolated from the blood. At autopsy, disseminated cytomegalovirus infection, extensive CNS toxoplasmosis and early lesions of Kaposi's sarcoma were demonstrated. The detection of HIV in the adrenal medulla supports the consensus that the virus is neurotropic.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Antibodies to delta antigen in asymptomatic hepatitis B surface antigen-reactive blood donors in the United States and their association with other markers of hepatitis B virus.

A total of 1,915 sera collected in 1979 from asymptomatic hepatitis B surface antigen (HBsAg) carriers were tested for delta antigen, antibody to delta antigen (anti-delta), hepatitis B e antigen (HBeAg) and antibody to hepatitis B e antigen (anti-HBe) in addition to HBsAg and its subtypes. These sera represented blood donated by volunteers to 49 of 57 regions of the American Red Cross located in nine geographic regions of the United States and Puerto Rico. A total of 72 (3.8%) sera had anti-delta activity while none had a detectable level of delta antigen. A significantly higher (p less than 0.01) prevalence of anti-delta (12.1%) was found in San Jose, California (Pacific Region); on the other hand, the East South Central region covering Alabama, Kentucky, Mississippi and Tennessee had a significantly lower (p less than 0.05) prevalence (1.4%) of anti-delta when compared with all other regions combined. Anti-delta was, however, detected in all regions of the United States and in Puerto Rico. The cause of significant differences in the prevalence of anti-delta was not clear. The distribution of anti-delta was not associated with age, sex or blood type of the donor. Sixty-nine of 70 samples with anti-delta were found among the 1,527 samples that had either HBeAg or anti-HBe. And among 149 that lacked both HBeAg and anti-HBe, only one sample had anti-delta. The difference is statistically significant (p less than 0.05). The presence of anti-delta was not associated with HBsAg/ad (2.7%) or HBsAg/ay (4.6%).

Adolescent↗
PubMed1982

Inactivation of DNA-polymerase associated with hepatitis B virus.

The effects of heat, sodium hypochlorite, diethyl ether, and ethyl alcohol on the activity of DNA polymerase (DNA-P) associated with hepatitis B virsus (HBV) in serum were evaluated. The response of DNA-P to heating at 60 degrees C for 15, 30, 45, 60, 90, 120, 180, and 240 minutes was studied and the data suggested that there may be two types of DNA-P. The majority of DNA-P was type 'a', and it showed a one log reduction (D60) at 60 degrees C in 36 minutes, while the remaining activity was type 'b' that showed a one log reduction (D60) in 340 minutes. Treatment of DNA-P with sodium hypochlorite at concentrations of 250 and 500 parts per million (ppm) of available chlorine resulted in a 20 to 25% reduction in DNA-P activity within one minute. Complete loss in detectable DNA-P activity occurred within one minute when available Cl- was 2500 ppm or greater. Various concentrations of ethyl alcohol (ranging from 10 to 70%) caused gradually increasing inactivation of DNA-P activity in ten minutes at 4 degrees C. Ninety percent inactivation occurred with 60% alcohol. Overnight treatment of DNA-P-reactive material with diethyl ether at 4 degrees C led to loss of detectable activity. A reduction in the titer of HBsAg was found following treatment with alcohol or ether. The possible use of DNA-P assay as an indicator of the rate of inactivation of HBV is proposed.

DNA-Directed DNA Polymerase↗
PubMed1982

Proficiency in testing for hepatitis B surface antigen: experience with Ausria II.

Eight hepatitis B surface antigen (HBsAg) proficiency panels were tested using a radioimmunoassay (RIA) test kit during 1978 and 1979 by routine processing laboratories within the 57 American Red Cross Blood Services Regions. The test results were analyzed and it was found that lot-to-lot variability in the reagents may result in a measurable loss of sensitivity of the test leading to an increased error rate. On the basis of these studies, it is recommended that the positive to negative (P/N) ratio for validation of the test be raised to at least 25.

Analysis of Variance↗
PubMed1981

A modified technique for the detection of hepatitis B virus-specific DNA polymerase.

A modified and improved technique for the detection of hepatitis B virus-specific DNA polymerase activity is described. DNA polymerase is released from Dane particles by mixing samples with the detergent Nonidet P-40 and beta-mercaptoethanol. After incubation of pretreated samples with a reaction mixture containing tritiated thymidine-methyl-5'-triphosphate (3H-TTP), DNA is precipitated onto a trichloroacetic acid (TCA)-treated paper. Unincorporated 3H-TTP is then chromatographically eluted with a 5% TCA solution and precipitated counts are determined. A sample is considered positive for DNA polymerase if the incorporated counts are significantly higher than the counts of a group of negative control samples. The modifications include pretreatment of the paper with TCA, chromatographic elution of unincorporated 3H-TTP with TCA solution, prefiltration of the sample through bacteriological filters, and use of sound statistical methods for evaluation of data. These changes have led to a highly reproducible, reliable and sensitive technique. The coefficient of variation of negative control samples from various test runs was in the range of 2.7-8.5%. A linear relationship between incorporated counts and DNA polymerase concentration was shown. A total of 419 serum samples from asymptomatic HBsAg-carrying blood donors were tested. Twenty-three (5.5%) of these were found to contain detectable DNA polymerase activity. All 23 samples also contained HBeAg.

Chemical Precipitation↗
PubMed1981

Comparative evaluation of radioimmunoassay kits used for testing blood for hepatitis B surface antigen.

A comparative evaluation of six licensed radioimmunoassay kits for the detection of hepatitis B surface antigen (HBsAg) has been performed. Each method met the federal licensure requirements for the test. The performance of the kits varied considerably, however, when they were challenged to the limits of their sensitivities. During the period December 1978 through March 1979, four kits were judged to be of equivalent high sensitivity, whereas two were less sensitive. Three of the kits, including two of those with high sensitivity, generated a high (6%--7%) proportion of false reactive results. The sensitivities of all kits decreased during the shelf lives of the reagents.

Evaluation Studies as Topic↗
PubMed1980

Distribution of hepatitis B e antigen (HBeAg) and anti-HBe in carriers with different levels of HBsAg.

Blood samples from 154 asymptomatic carriers of HBsAg were studied for the presence of HbeAg and anti-HBe using techniques of rheophoresis and a micro solid phase radioimmunoassay (micro-SPRIA). The level of HBsAg in each sample was determined by titration using reverse passive hemagglutination (RPHA) test. The significance of relationship between the titer of HBsAg, HBeAg, anti-HBe, and anti-HBc were statistically analyzed. Micro-SPRIA detected almost twice as many reactives for HBeAg and anti-HBe as were found by rheophoresis; the difference in sensitivity was significant (P less than 0.001). The mean HBsAg titer of 41 samples reactive for HBeAg was 11,181, while it was 3,032 for 92 samples reactive for anti-HBe. The remaining 23 samples with no detectable HBeAg or anti-HBe had a mean HBsAg titer of 1,018. The differences in the distribution of HBsAg among the three categories is statistically significant (P less than 0.005). HBeAg was most likely to be found in samples with higher concentrations of HBsAg.

Antibodies, Viral↗