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Biomedical subjects

S F Lin

Publications and source records attributed to S F Lin.

At least 55 records · Page 3Linked to original sources
PubMed1999

Kinetics of Kaposi's sarcoma-associated herpesvirus gene expression.

Herpesvirus gene expression can be classified into four distinct kinetic stages: latent, immediate early, early, and late. Here we characterize the kinetic class of a group of 16 Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus 8 genes in a cultured primary effusion cell line and examine the expression of a subset of these genes in KS biopsies. Expression of two latent genes, LANA and vFLIP, was constitutive and was not induced by chemicals that induce the lytic cycle in primary effusion lymphoma (PEL) cell lines. An immediate-early gene, Rta (open reading frame 50 [ORF50]), was induced within 4 h of the addition of n-butyrate, and its 3.6-kb mRNA was resistant to inhibition by cycloheximide. Early genes, including K3 and K5 that are homologues of the "immediate-early" gene of bovine herpesvirus 4, K8 that is a positional homologue of Epstein-Barr virus BZLF1, vMIP II, vIL-6, and polyadenylated nuclear (PAN) RNA, appeared 8 to 13 h after chemical induction. A second group of early genes that were slightly delayed in their appearance included viral DHFR, thymidylate synthase, vMIP I, G protein-coupled receptor, K12, vBcl2, and a lytic transcript that overlapped LANA. The transcript of sVCA (ORF65), a late gene whose expression was abolished by Phosphonoacetic acid, an inhibitor of KSHV DNA replication, did not appear until 30 h after induction. Single-cell assays indicated that the induction of lytic cycle transcripts resulted from the recruitment of additional cells into the lytic cycle. In situ hybridization of KS biopsies showed that about 3% of spindle-shaped tumor cells expressed Rta, ORF K8, vIL-6, vMIP I, vBcl-2, PAN RNA, and sVCA. Our study shows that several KSHV-encoded homologues of cellular cytokines, chemokines, and antiapoptotic factors are expressed during the viral lytic cycle in PEL cell lines and in KS biopsies. The lytic cycle of KSHV, probably under the initial control of the KSHV/Rta gene, may directly contribute to tumor pathogenesis.

Chemokines↗
PubMed1999

Allogeneic bone marrow transplantation of chronic myeloid leukemia from an HLA-matched unrelated donor with the beta-thalassemic trait.

We report a chronic myeloid leukemia patient who underwent allogeneic bone marrow transplantation from an HLA-matched unrelated donor with the beta-thalassemic trait. The donor was a heterozygote for the -28 A-->G mutation. We examined the recipient's bone marrow and peripheral blood using the polymerase chain reaction (PCR) method to detect the -28 G-->A mutation of the donor type and monitored the sustained engraftment. This case suggests that a donor with the thalassemic trait can be a candidate for matched unrelated bone marrow transplantation for hematological malignancies and that PCR based genetic examination of the thalassemic mutation is a useful tool to detect early engraftment.

Adult↗
PubMed1999

Kimura's disease of bilateral upper eyelids: a case report.

We present a rare case of Kimura's disease of bilateral upper eyelids. A 41-year-old Chinese male had multiple masses over retroauricular, submandibular regions and bilateral upper eyelids since 13 years previously. Tumor recurred after each surgical excision, chemotherapy and Co 60 radiotherapy. Eosinophilia and elevation of blood immunoglobulin E (IgE) were noted in this admission. We operated on left upper eyelid to relieve the blocking of vision. A diffuse infiltration with numerous fibrotic bands was noted. Histological section showed a lymphoid hyperplasia, remarkable infiltration of eosinophils and proliferation of capillaries. Oral prednisolone 60 mg was given postoperatively. The patient had a satisfactory appearance and a relief of visual block.

Adult↗
PubMed1998

A viral gene that activates lytic cycle expression of Kaposi's sarcoma-associated herpesvirus.

Herpesviruses exist in two states, latency and a lytic productive cycle. Here we identify an immediate-early gene encoded by Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus eight (HHV8) that activates lytic cycle gene expression from the latent viral genome. The gene is a homologue of Rta, a transcriptional activator encoded by Epstein-Barr virus (EBV). KSHV/Rta activated KSHV early lytic genes, including virus-encoded interleukin 6 and polyadenylated nuclear RNA, and a late gene, small viral capsid antigen. In cells dually infected with Epstein-Barr virus and KSHV, each Rta activated only autologous lytic cycle genes. Expression of viral cytokines under control of the KSHV/Rta gene is likely to contribute to the pathogenesis of KSHV-associated diseases.

Amino Acid Sequence↗
PubMed1998

Distinct regions of EBV DNase are required for nuclease and DNA binding activities.

Epstein-Barr virus (EBV) DNase possesses both endonuclease and exonuclease activities and accepts both double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) as substrates. To map regions of EBV DNase responsible for nuclease and DNA binding activities, a series of mutant DNase polypeptides was expressed using a bacterial system for the nuclease assay and in an in vitro transcription/translation system to assay binding activity to dsDNA or ssDNA cellulose. The results indicated that the C-terminus of EBV DNase, residues 450-460, is essential for nuclease activity but dispensable for DNA binding. However, deletion of residues 441-470 resulted in the loss of both nuclease and DNA binding activities. Substitution of Phe452 and Val458 led to inactive enzymes. In the N-terminus, deletion of residues 23-28 and residues 7-61 resulted in the loss of nuclease activity but the DNA binding activities of the deleted enzymes were intermediate and low, respectively. Mutation of Leu23 to Gly showed drastically reduced nuclease activity but its DNA binding ability was not affected. Based on the amino acid sequence alignment of various herpesvirus DNases, we chose four highly conserved and two less well conserved regions as controls for mutagenesis studies. These six internal deletion (ID) mutants were prepared using a recombinant PCR method. Each of the polypeptides was expressed in a bacterial system for the nuclease assay and using an in vitro transcription/translation system for the DNA binding assay. DNA binding and nuclease activities of all six internal deletion mutants were abolished, except that mutant ID2, with deletion of residues 138-152, retained an intermediate ability to bind DNA. These data indicate that since mutations at distinct regions within EBV DNase resulted in the loss of nuclease and/or DNA binding activities, it is suggested that these distinct regions are required for maintenance of an intact and highly ordered structure(s) for both activities.

Amino Acid Sequence↗
PubMed1998

Serologic association of human herpesvirus eight with posttransplant Kaposi's sarcoma in Saudi Arabia.

BACKGROUND: This study investigates the association between human herpesvirus eight (HHV8) and Kaposi's sarcoma (KS), the most common cancer occurring in renal transplant recipients in Saudi Arabia. METHODS: A cross-sectional study of seroreactivity to HHV8 antigens in posttransplant KS patients from a tertiary care hospital in Riyadh, Saudi Arabia, and in control subjects without KS was conducted. Seroreactivity rates were determined using immunoblotting assays to detect antibodies to two lytic cycle HHV8 antigens: p40, an antigen found in infected cells, and sVCA, an HHV8-encoded small viral capsid antigen expressed in Escherichia coli. RESULTS: Antibodies to HHV8 p40 and sVCA were present in a significantly higher proportion of renal transplant patients with KS (13 of 14 patients) compared to renal transplant patients without KS (5 of 18; P<0.001) and compared to other control individuals (6 of 44; P<0.001). HHV8 seroreactivity was more common among patients with renal failure (28%) than among other control groups (7%). CONCLUSIONS: The serologic results provide evidence of a strong association between HHV8 and posttransplant KS in Saudi Arabia.

Antibodies, Viral↗
PubMed1998

Aberrant TSG101 transcripts in acute myeloid leukaemia.

Recently, a tumour susceptibility gene, TSG101, has been identified at chromosome 11p15. A large intragenic deletion of this gene has been demonstrated in primary breast tumours. To evaluate the role of the TSG101 gene in leukaemia, bone marrow and/or peripheral blood from 68 acute myeloid leukaemia patients, five haemopoietic cell lines (HL60, U937. Raji, KG-1, K562) and 30 normal controls were analysed by reverse transcription of the TSG101 mRNA, followed by PCR amplification and sequencing of the products. The results showed aberrant TSG101 transcripts in 24/68 (35%) acute myeloid leukaemia (AML) patients, all of the cell lines (100%) and 3/30 (10%) normal controls. Our study indicated that the abnormal transcripts may have resulted from aberrant RNA splicing as evidenced by these aberrant transcripts. Also, normal full-length transcripts were present in all specimens examined. The aberrant transcript occurred more frequently in the AML and cell lines. However, because aberrant transcripts of TSG101 were also found in the normal controls, the role of TSG101 as a tumour suppressor gene should be evaluated carefully.

Acute Disease↗
PubMed1998

High prevalence of antibodies to human herpesvirus 8 in relatives of patients with classic Kaposi's sarcoma from Sardinia.

A survey for antibodies to a recombinant small viral capsid antigen (sVCA) of human herpesvirus type 8 (HHV-8) was conducted in Sardinia, one of the world's highest incidence areas for classic Kaposi's sarcoma (KS). Prevalence of antibodies to HHV-8 sVCA was greatest in patients with KS (95%), followed by family members (39%) and a Sardinian control population age- and sex-matched to the relatives (11%). Within families, prevalence of antibodies was about equal among spouses, children, and siblings of KS patients, a finding that raises the possibilities of intrafamilial person-to-person or vertical transmission. Antibodies were detected 2-3 times more frequently in males than in females. The data show that prevalence of antibodies to HHV-8 sVCA correlates with the distribution of classic KS in a high- incidence area. Clustering of seroprevalence within some families suggests the presence of familial risk factors for active HHV-8 infection.

Age Factors↗
PubMed1998

Identification of Bacillus cereus by Fourier transform infrared spectroscopy (FTIR).

The objective of this study was to evaluate the potential of Fourier transform infrared spectroscopy (FTIR) for rapid identification of Bacillus cereus isolates. Ten B. cereus group isolates (comprising B. cereus, Bacillus mycoides, and Bacillus thuringiensis strains), five other Bacillus spp., and five non-Bacillus spp. were used. Two types of media, brain heart infusion (BHI) and Trypticase soy agar (TSA), were tested. The results indicated that all B. cereus group isolates produced characteristic absorbance peaks at wave numbers between 1738 and 1740 cm-1. These peaks were not affected by the growth medium. None of the other bacteria tested showed a similar peak after growth on BHI or TSA. Absorbance peaks between 1800 and 1500 cm-1 of members of the B. cereus group had different shapes and sizes, suggesting that FTIR may be useful for rapid identification of species within the B. cereus group.

Bacillus cereus↗
PubMed1998

Donor leukocyte infusion as salvage therapy in an adult with relapsed acute lymphoblastic leukemia after allogeneic bone marrow transplantation.

Relapse of malignancy after allogeneic bone marrow transplantation remains the major cause of treatment failure in patients with leukemia. While donor leukocyte infusion (DLI) has been used to treat such patients, its use in patients with acute lymphoblastic leukemia is seldom reported. We describe a 35-year-old woman who suffered relapse of acute lymphoblastic leukemia after allogeneic bone marrow transplantation. She received DLI twice as salvage therapy. This patient achieved complete remission following DLI and has remained in remission for more than 11 months without further chemotherapy. We suggest DLI can be used as an initial salvage therapy, without significant toxicity, for patients with relapsed acute lymphoblastic leukemia following bone marrow transplantation.

Adult↗
PubMed1997

Prenatal diagnosis of thalassemia in the Chinese.

There is a high prevalence of thalassemia in the Taiwan area. Prenatal diagnosis of severe forms of thalassemia is important for the prevention of this disease. We performed prenatal diagnosis in 167 cases, of which 59 cases were diagnosed by chorionic villi biopsy, 91 cases by amniotic fluid analysis, and 17 cases by cord blood analysis. Hb Bart's hydrops was detected by amplifying the break junction area of the alpha-thalassemia-1 Southeast Asia (SEA)-type gene, and beta-thalassemia major was detected by using naturally occurring restriction sites and the amplified created restriction sites (ACRS) method. Screening for hemoglobin (Hb) Bart's hydrops revealed 26 cases of Hb Bart's hydrops, 67 cases of alpha-thalassemia-1 (including 6 Hb Bart's hydrops falsely diagnosed as alpha-thalassemia-1 from chorionic villi samples), and 38 normal cases. Screening for beta-thalassemia major revealed 8 cases of beta-thalassemia major, 17 cases of beta-thalassemia minor, and 11 normal cases. In cases of alpha-thalassemia, maternal tissue contamination in the chorionic villi samples occurred in the diagnosis of the carrier state and further amniotic fluid analysis will be necessary. There were no any false-positive or false-negative results in beta-thalassemia major screening. We conclude that prenatal diagnosis is a reliable and accurate screening method for thalassemia and may be valuable in other areas of high prevalence for thalassemia in Southeast Asia and in Southern China.

Gene Frequency↗
PubMed1997

The transcriptional activator Sp1, a novel autoantigen.

OBJECTIVE: To identify one nuclear autoantigenic protein within a complex of DNA binding proteins that bind to GC-rich sequences in Epstein-Barr virus and cellular DNA, and to describe the clinical characteristics of patients whose sera contained autoantibodies to this novel autoantigen. METHODS: Antibodies to autoantigen Sp1 were initially measured by an electrophoretic mobility shift assay to detect DNA binding proteins. Nuclear extracts and purified Sp1 protein were used in these assays. Recognition of the autoantigen by autoimmune sera was confirmed by immunoprecipitation and immunoblotting. RESULTS: The autoantigen was identified as Sp1. Anti-Sp1 was detected in sera from 8 (3%) of 230 patients. These sera contained antinuclear antibodies, but lacked antibodies to double-stranded DNA or to several extractable nuclear antigens. The patients whose sera contained antibodies to Sp1 were white women with fatigue, arthritis, Raynaud's phenomenon, malar rash, and photosensitivity. CONCLUSION: Sp1 is the first described example of an RNA polymerase II transcription activator as an autoantigen. The presence of Sp1 autoantibodies is associated with undifferentiated connective tissue disease.

Adult↗
PubMed1997

Aberrant FHIT transcripts in acute myeloid leukaemia.

Recently the FHIT gene (fragile histidine triad gene) has been identified at chromosome 3p14.2 and a high frequency of abnormalities in this gene has been demonstrated in various cancers. To determine the role of the FHIT gene in leukaemia, bone marrow or peripheral blood from 62 acute myeloid leukaemia patients and five haemopoietic cell lines (HL60, U937, Raji, KC-1, K562) were analysed by reverse transcription of the FHIT mRNA followed by PCR amplification and sequencing of the products. To detect the deletion of the FHIT gene, 17 cases were evaluated using microsatellite polymorphism analysis. In this study, 17/62 (27%) AML patients expressed aberrant transcripts which lack two or more exons of the FHIT gene, and all the cell lines exhibited the aberrant FHIT transcripts. No cases exhibited a loss of the FHIT alleles. Our data indicated that the FHIT gene may play a role in myeloid carcinogenesis and may be indicated in the late progression of the disease.

Acute Disease↗
PubMed1997

Identification, expression, and immunogenicity of Kaposi's sarcoma-associated herpesvirus-encoded small viral capsid antigen.

We describe a recombinant antigen for use in serologic tests for antibodies to Kaposi's sarcoma (KS)-associated herpesvirus (KSHV). The cDNA for a small viral capsid antigen (sVCA) was identified by immunoscreening of a library prepared from the BC-1 body cavity lymphoma cell line induced into KSHV lytic gene expression by sodium butyrate. The cDNA specified a 170-amino-acid peptide with homology to small viral capsid proteins encoded by the BFRF3 gene of Epstein-Barr virus and the ORF65 gene of herpesvirus saimiri. KSHV sVCA was expressed from a 0.85-kb mRNA present late in lytic KSHV replication in BC-1 cells. This transcript was sensitive to phosphonoacetic acid and phosphonoformic acid, inhibitors of herpesvirus DNA replication. KSHV sVCA expressed in mammalian cells or Escherichia coli or translated in vitro was recognized as an antigen by antisera from KS patients. Rabbit antisera raised to KSHV sVCA expressed in E. coli detected a 22-kDa protein in KSHV-infected human B cells. Overexpressed KSHV sVCA purified from E. coli and used as an antigen in immunoblot screening assay did not cross-react with EBV BFRF3. Antibodies to sVCA were present in 89% of 47 human immunodeficiency virus (HIV)-positive patients with KS, in 20% of 54 HIV-positive patients without KS, but in none of 122 other patients including children born to HIV-seropositive mothers and patients with hemophilia, autoimmune disease, or nasopharyngeal carcinoma. Low-titer antibody was detected in three sera from 28 healthy subjects. Antibodies to recombinant sVCA correlate with KS in high-risk populations. Recombinant sVCA can be used to examine the seroepidemiology of infection with KSHV in the general population.

AIDS-Related Opportunistic Infections↗
PubMed1997

Sp1 binds to the precise locus of end processing within the terminal repeats of Epstein-Barr virus DNA.

Interconversion between the linear genome of Epstein-Barr virus (EBV) present in virions and intracellular circular EBV DNA is a novel DNA recombination process. A previously characterized DNA binding activity called terminal repeat or tandem repeat binding protein (TRBP) was found to recognize several G-rich recombinogenic sequences in the EBV genome and in cellular DNA. TRBP was also found to be an autoantigen recognized by sera from certain patients with undifferentiated connective-tissue disorders. Here the transcription factor Sp1 has been identified as a component of TRBP and has been shown to be an autoantigen. Sp1 bound to recombination junctions of EBV DNA, such as those in the terminal repeats and in the large internal repeats, as well as to recombinogenic regions of cellular DNA, such as variable-number tandem repeats and switch regions of the immunoglobulin genes. We defined the ends of the linear EBV genome present in virions and showed that Sp1 binds to the sequence (GGGGTGGGGCATGGG) within EBV terminal repeats at the precise locus of interconversion of linear and circular viral DNA. Sp1 may be involved in DNA recombination.

Animals↗