Use of bacterially expressed GST/EBNA-1 fusion proteins for detection of antibodies in sera from patients with nasopharyngeal carcinoma and healthy donors

Epstein-Barr virus nuclear antigen-1 (EBNA-1) is a protein expressed consistently in EBV infected cells and in EBV related malignant tissues. Antibodies against EBNA-1 may therefore possibly be used as a marker for disease screening. Western blot analysis of serum antibodies was performed using GST (glutathione-S-transferase) fusion proteins containing different regions of EBNA-1 as antigens. Serum samples were collected from 38 patients with nasopharyngeal carcinoma (NPC) and 38 healthy individuals in Taiwan. All samples were found IgG positive for EBNA-1 when a truncated protein GST/E1 (70-102, 325-641) was used as the antigen. Thirty-three out of 38 NPC sera (86.8%) were positive for IgA antibody against EBNA-1. The positive rate was higher in comparison with IgA antibody against VCA (65.7%) or antibody against DNase (60.5%). Only 2.6% of sera from normal individuals were positive for an IgA response against EBNA-1. The major antigenic determinants for NPC serum IgA response were between amino acid(aa) 390 to aa 459 when different portions of EBNA-1 were used as antigens. The results suggest that IgA response against EBNA-1 could be used in combination with other EBV serology markers for NPC screening.

Prenatal detection of two different monosomic cell lines by chorionic villus sampling

We present a prenatal case of mosaicism with at least two monosomy cell lines: one with monosomy 21 (45,XY,-21) and one missing the Y (45,X) and a possible third 46,XY in chorionic villus cell culture. Cytogenetic studies were initiated following the ultrasound detection at 11 weeks of a large cystic hygroma and in utero growth retardation. Spontaneous fetal demise occurred at 12 weeks and the pregnancy was terminated. To our knowledge, this is the first report of two different monosomic cell lines found in chorionic villus cells.

Characterization of Epstein-Barr virus DNase and its interaction with the major DNA binding protein

Bacterially expressed Epstein-Barr virus (EBV) DNase was purified to 98% purity and used as the source for characterization of the enzyme activities. Complete digestion of DNA by EBV DNase yielded 5'-monophosphate nucleosides as the final products. During the logarithmic phase of the reaction, EBV DNase acted processively on dsDNA but distributively on ssDNA. Both 5' to 3' and 3' to 5' exonuclease activities were present, although the former was shown to be 10-fold stronger. No significant discrepancy was seen in the liberation of end-labeled nucleotides by DNase when substrates with 5'-protruding, blunt, or 3'-protruding ends were used. EBV DNase was demonstrated also to have an endonuclease activity using supercoiled plasmid DNA as substrate. Two preferential dsDNA cleavage sites were mapped on pBS-TR, a pBlueScript vector containing one copy of the EBV terminal repeat; both are in vector sequences. Finally, an N-terminally truncated EBV major DNA binding protein, but not EA-D, was shown to inhibit EBV DNase activity. This inhibitory effect may due to direct protein-protein interactions between EBV DNase and the major DNA binding protein. The biological significance of these characteristics is discussed.

Inverse polymerase chain reaction for cloning cellular sequences adjacent to integrated hepatitis B virus DNA in hepatocellular carcinomas

Integration of hepatitis B virus (HBV) DNA is found in most HBV-related human hepatocellular carcinomas (HCCs). In the past, construction of genomic libraries was mainly employed to study the role of viral integration. However, large amounts of tissue DNA and a laborious screening procedures were required. Inverse polymerase chain reaction (IPCR) is based on the simple procedures of digestion of DNA with restriction enzymes and circularization of cleavage products before amplification using primers synthesized in the opposite orientations to those normally employed for PCR. This technique allows the in vitro amplification of DNA flanking a region of known sequence. By employing this method, starting from nanograms of hepatoma DNA, two adjacent cellular sequences were cloned from 11 HBV integrants in three HCCs. The original configurations in the chromosomes were further confirmed. One of the flanking cellular sequences was identified as the human 28S rRNA gene, the other was not found homologous to any known human sequences. This method appears to be practical and can be improved further to clone more flanking cellular sequences, especially in early and small HCCs.

Abdominal pregnancy--report of two cases and review of literature

Ectopic pregnancy is one of the major complications of pregnancy. The abdominal pregnancy is a comparatively rare type of ectopic gestation with a high fetal and maternal morbidity and mortality. Although abdominal pregnancy had been well documented, it still remains a serious dilemma for most clinicians in the contemporary obstetric practice because of the difficulties in early diagnosis and proper management. We reported two cases of early abdominal pregnancy with accurate preoperative diagnosis followed by immediate surgical intervention and total removal of the placental tissue. The important concepts of management with this uncommon but ominous condition are discussed, including the predisposing risk factors, clinical features, diagnostic difficulties, appropriate surgery and management of the placenta.

Analysis of integrated hepatitis B virus DNA and flanking cellular sequences in a childhood hepatocellular carcinoma

The DNA of tumor tissue K1 obtained at autopsy from a case of hepatocellular carcinoma (HCC) in a 9-year-old boy contained integrated hepatitis B virus (HBV) DNA at a single site in the chromosome (case 2, Chang et al.: Hepatology 13:316-320, 1991). To characterize further the integrated viral DNA sequences, a genomic library of the K1 DNA was constructed in the lambda L47.1 vector. One phage clone, designated KTM-1, containing integrated HBV DNA and cellular flanking sequences was obtained from this library. The restriction map and DNA sequence of this clone showed that the integrated HBV DNA was partially deleted and rearranged. The most conserved viral DNA sequences were surface and X genes and arranged in the opposite orientation. The viral core gene was not present. Using chloramphenicol acetyltransferase (CAT) assay, the C-terminal truncated X open reading frame was demonstrated to retain its trans-activating ability. The result suggested that the functional integrated X gene may play a role in hepatocarcinogenesis. The study also showed that the right cellular flanking sequences were human alphoid repetitive sequences.

Liver-specific expression and high oncogenic efficiency of a c-myc transgene activated by woodchuck hepatitis virus insertion

The high oncogenic efficiency of woodchuck hepatitis virus (WHV) has been correlated with the ability of this virus to provoke insertional activation of myc family genes. To assess the impact of viral integration on liver cell transformation, we have generated transgenic mice carrying the mutated c-myc gene and adjacent viral DNA from a woodchuck tumor, in original configuration. Virtually all mice from two different strains developed hepatocellular carcinoma with a mean latency period of 8-12 months. The c-myc transgene was expressed transiently in neonatal livers, and re-expressed at preneoplastic and neoplastic stages in adult livers. Woodchuck c-myc mRNA driven by the normal P1 and P2 promoters and WHV-specific transcripts encoding viral surface antigens were produced in a strictly co-regulated fashion during development and tumorigenesis, indicating a predominant regulatory influence of the viral enhancer. Furthermore, the activity of the viral enhancer in response to various biological stimuli was apparently modulated by glucose uptake and glucagon/insulin balance in differentiated hepatocytes. In this model, a viral integration event selected from a naturally occurring tumor proved to be determinant for induction of hepatocarcinogenesis, although enforced, liver-specific expression of c-myc was limited to a particular developmental stage.

Functional analysis of the amino terminus of Epstein-Barr virus deoxyribonuclease

A cDNA coding for the Epstein-Barr virus (EBV) alkaline deoxyribonuclease (DNase) was expressed in Escherichia coli using the T7 phage system designed to allow expression of potentially lethal proteins. Induction of protein synthesis from the gene yielded a peptide with a molecular weight of approximately 52 kDa, consistent with the predicted open reading frame of EBV BGLF5. A high level of nuclease activity was detected in crude cell extracts, and the activity was neutralized by sera from nasopharyngeal carcinoma patients with high titers of anti-DNase antibodies. A series of deletion clones truncated at the amino or carboxyl terminus was constructed and expressed to define the regions responsible for the nuclease activity of EBV DNase. All the mutated molecules lost their activities even though their expression levels were comparable to that of the full-length DNase. To determine the exact role of the amino terminus of EBV DNase, mutants with small deletions were expressed. While three mutants with deletions of amino acid residues 11-30, 16-28, or 23-28 failed to show any detectable nuclease activities, one mutant in which the first 8 amino acids were replaced by the first 12 amino acid residues of the T7 major capsid protein contributed by the vector was enzymatically active. To further define the importance of the amino-terminal region, full-length DNase with point mutations was generated among residues 23-29 by site-directed mutagenesis and expressed in the same system. Assays of the DNase activity of these mutants revealed that the mutation of residue 29 was fully active, and mutations in 24-27 retained 50% activity. Nevertheless, the mutation at residue 23 resulted in a complete loss of activity and the mutation at residue 28 resulted in loss of 70% activity. These results suggest the biological importance of the amino terminus of the EBV DNase, especially residues 23-28.

Postmortem chorionic villus sampling for cytogenetic evaluation of early fetal loss: a simple reliable method

BACKGROUND

Early fetal losses associated with chromosome abnormalities produce most spontaneous abortions. It is not feasible to conduct cytogenetic studies with tissue culture postmortem because of tissue maceration and autolysis.

METHODS

A total of 30 specimens from early fetal losses were karyotyped for chromosomal study. Success rate of the culture method is evaluated and compared.

RESULTS

The abnormal karyotype rate was 33.3%. It was found that chorionic villus tissues had a higher culture rate than tests of fetal skin, amnion or amniocyte by early amniocentesis.

CONCLUSIONS

Postmortem chorionic villus sampling at the time of diagnosis of early fetal death appears to offer the best, most simple and reliable method for obtaining a cytogenetic result, and also a good method for training residents in the chorionic villus sampling technique.

Stability of HBV DNA in cell lines and nude mouse-passaged tissues derived from human hepatocellular carcinoma

Human hepatitis B virus (HBV) infection has been closely linked to the occurrence of hepatocellular carcinoma (HCC). Hepatoma cell lines and nude mouse-passaged hepatoma tissues were used in this report to study the HBV DNA status in these cells after passage. DNA was extracted from seven hepatoma cell lines and three nude mouse passaged HCC lines. Southern blot hybridization technique was performed with either cloned HBV whole genome or subgenomic DNA fragments as probes to analyze the presence of HBV DNA. Integration of HBV DNA fragments was detected in one mouse passaged tissue, R. Hybridization with HBV subgenomic DNA revealed that there were some DNA rearrangements of the integrated HBV DNA in R. However, the integrated HBV DNA could not be detected in the cell line derived from R after in vitro cultivation for 2 years. Both episomal form and integrated HBV DNA were detected in a cell line NTU-h3. Episomal form HBV DNA ih NTU-h3 changed after several passages. HBV DNA in NTU-h3 was unstable after in vitro cultivation. Therefore, we concluded that the presence of HBV DNA might not be essential for the maintenance of the tumorigenicity of hepatoma and the nude mouse system was more stable for maintaining HBV DNA in HCC.

Analysis of integrated hepatitis B virus DNA and flanking cellular sequences in the hepatocellular carcinoma cell line HCC36

A hepatocellular carcinoma cell line, HCC36, was established from an adult HBV carrier in Taiwan. From Southern blot analysis, there were at least four sites of integration of HBV DNA, and no viral replicative intermediates were detected. A genomic library was constructed from HCC36 DNA, and two phage clones, designated lambda 36A and lambda 36B, were shown to contain HBV DNA and flanking cellular sequences. In lambda 36A, HBV DNA sequences were quite conserved, and 7.4% base variation was detected. The viral sequences in lambda 36A and lambda 36B differed in only four bases, in addition to the microdeletion and -insertion observed in lambda 36B. The flanking cellular sequences identified in lambda 36A were human Alu sequences and in lambda 36B satellite sequences.

Establishment and characterization of an HTLV-I cell line from a Taiwanese patient with HTLV-I-associated myelopathy

We describe a Taiwanese woman with chronic progressive myelopathy, in whom Western blot analysis of the serum and cerebrospinal fluid (CSF) displayed positive reactions to human T-lymphotropic virus type I (HTLV-I) proteins, p19, p24, p28, p36, gp46 and p53. HTLV-I proviral genomes were detected in the peripheral blood mononuclear cells (PBMC) and CSF cells by nested polymerase chain reaction and Southern blot hybridization. HTLV-I was successfully isolated from PBMC stimulated with interleukin-2 (IL-2). The established cell line, named THAM-1, was an IL-2-independent T-cell line with CD2+, CD3+, CD4+, CD25+ and HLA-DR+. Retrovirus particles with type C morphology were observed in the THAM-1 cells by electron microscopy, and HTLV-I-related antigens were also demonstrated by immunocytochemical staining and Western blot assay. Southern blot analysis revealed that HTLV-I proviral genomes were integrated into the THAM-1 cellular DNA. In Northern blot analysis, two extra-species of RNA were detected in addition to three typical viral transcripts. For the first time, an HTLV-I-producing T cell line was established from a patient with HTLV-I-associated myelopathy in Taiwan, an HTLV-I non-endemic area.

Use of bacterially-expressed antigen for detection of antibodies to the EBV-specific deoxyribonuclease in sera from patients with nasopharyngeal carcinoma

A cDNA clone, BG9, corresponding to the open reading frame BGLF5 of Epstein-Barr virus (EBV) DNase was inserted into an E. coli expression vector, pET3a, to generate a recombinant plasmid, pDNase 5. High level of expression of a DNase activity was detected in the E. coli transformed with pDNase 5 following induction with IPTG. The enzyme activity was purified using DEAE-cellulose, phosphocellulose and DNA-cellulose column chromatography. The purified protein appeared to be nearly homogeneous in SDS-PAGE using Coomassie blue staining. The requirement for divalent cations and optimum pH as well as inhibitory concentrations of ionic strength and polyamines for the purified enzyme activity were determined and seemed to be very similar to those of the enzyme activity purified from an EBV producing lymphoblastoid cell line. Using the purified enzyme as an antigen and anti-IgA as the secondary antibody, 82% (64/78) and 91% (71/78) of sera from patients with nasopharyngeal carcinoma (NPC) were shown to be positive by dot immunobinding assay and ELISA, respectively. The results suggest that purified E. coli expressed EBV DNase may be useful for preparing specific test for large scale screening of patients with NPC.

Analysis of Epstein-Barr virus BamHI F DNA fragment in nude mouse-passaged nasopharyngeal carcinoma tissues

Two nude mouse-passaged nasopharyngeal carcinoma (NPC) tissues, NPC-295 and NPC-306, were different in ability to transform cord blood lymphocytes and contained Epstein-Barr virus (EBV) genomes with difference in BamHI F DNA fragment. Four clones containing DNA sequences of the BamHI F fragment (54,853-62,249) were obtained from genomic libraries of NPC-295 and NPC-306 and their partial restriction enzyme maps and sequences were determined. The restriction enzyme maps of EBV DNA at the BamHI F fragment in NPC-295 and NPC-306 appeared to be similar to that of EBV B95-8 strain. However, 8 nucleotide differences were revealed between NPC-295 and the B95-8 strain when 566 nucleotides (55,405-55,970) were compared, and 15 out of 677 nucleotides analyzed (55,410-56,086) were different between NPC-306 and B95-8.

Analysis of a DNA polymorphic region in the gtfB and gtfC genes of Streptococcus mutans

We have previously demonstrated the existence of DNA polymorphisms at the 5' coding regions of the gtfB and gtfC genes specifying the streptococcal glucosyltransferases (J.S. Chia, T.Y. Hsu, L.J. Teng, J.Y. Chen, L.J. Hahn, and C.S. Yang, Infect. Immun. 59:1656-1660, 1991). DNA sequence analysis by polymerase chain reaction and direct sequencing revealed that while several nucleotide changes were identified, accounting for the polymorphisms, the amino acids which they code for remain unchanged. The polymorphic region is located in a highly conserved amino terminus of the glucosyltransferases. A peptide of 19 amino acids from this region reversed the inhibiting activity of an antiserum raised against the proteins coded for by the gtfB and gtfC genes. The results suggest that the polymorphic region, varying in DNA but not in amino acid sequences, might specify some biological function.

Use of antigen expressed in bacteria for detection of EBV-specific thymidine kinase antibodies in sera from patients with nasopharyngeal carcinoma

Two cDNA clones covering the N- and C-terminal portions of the EBV BXLF1 open reading frame were selected from a cDNA library derived from P3HR1 cells. The two clones were ligated, the N-terminal untranslated region truncated, and the product inserted into an E. coli expression vector, pET3CP*. The fusion protein was expressed under control of the T7 phage phi 10 gene promoter and shown to possess thymidine kinase activity. The protein was then used as an antigen to detect antibody reactivities in serum samples of nasopharyngeal carcinoma patients and healthy blood donors. Using a 1:400 dilution of serum samples in Western blot analyses, it was possible to differentiate the reactivities of serum IgA of NPC patients and healthy donors. The prevalence of positive reactivity to EBV TK in NPC was around 84%. The test was compared to others used for early diagnosis of NPC and was able to detect some patients who were negative in those tests.

Cloning and expression of a cDNA encoding the Epstein-Barr virus thymidine kinase gene

A clone of the Epstein-Barr virus (EBV) thymidine kinase (TK) gene was derived from a cDNA library of P3HR1 cells. The gene product was expressed as a fusion protein in a procaryotic system by using T7 RNA polymerase. The recombinant TK showed a molecular mass of 67 kDa and was biologically active. Antiserum raised in mice immunized with partially purified TK recognized an antigen present in EBV-superinfected Raji cells using an indirect immunofluorescence assay.

Cloning and characterization of cDNA clones corresponding to transcripts from the BamHI G region of the Epstein-Barr virus genome and expression of BGLF2

A cDNA library was constructed from poly(A)+ RNA isolated from the iododeoxyuridine-treated P3HR1 cell line. Five cDNA clones, which hybridized with the BamHI G fragment of Epstein-Barr virus (EBV) DNA, were subcloned and sequenced. Clones G2, G3 and G4 corresponded to the BGLF2 open reading frame (ORF) of EBV (B95-8, nucleotides 126,837 to 125,866); G3 was found to contain the entire BGLF2 ORF. The predicted Mr of the putative protein product of the EBV B95-8 BGLF2 ORF is 36K. Complete nucleotide sequencing of G3 revealed that there were two nucleotide changes from the reported sequence of the EBV B95-8 BGLF2 gene, but these did not alter the predicted amino acid sequence of the products. Clone G3 and a cDNA derived from it by N-terminal deletion were expressed in Escherichia coli, producing fusion proteins. Rabbit antisera against these proteins were shown to react with viral capsid antigen-expressing HR1 cells in an indirect immunofluorescence assay. In vitro transcription/translation products and fusion proteins expressed in E. coli were used to determine the presence of antibodies in sera from EBV-infected individuals. The results of immunoprecipitation and immunoblotting studies showed that the majority of EBV-seropositive individuals mount a serum antibody response to the BGLF2 ORF-encoded protein.

[Emergency obstetric hysterectomy: report of fifteen cases]

From June 1978 to June 1990, there were 41,989 deliveries, 13,396 cesarean sections and 15 emergency obstetric hysterectomies at Taipei Chang Gung Memorial Hospital. The incidence of emergency obstetric hysterectomy is 36/100,000 deliveries. The mean age of patients is 31.7 years old. The indications for hysterectomy were placental disorder (60.0%), uterine atony (26.7%), and uterine rupture (13.3%). The present series showed that 14 cases had total abdominal hysterectomy, while only one case had a subtotal hysterectomy. Total hysterectomy should generally be performed unless maternal instability mandates a more expeditious subtotal hysterectomy. The most common postoperative complication included unknown fever and urinary tract infection. For those four cases of post-cesarean hysterectomy, conservative treatment was tried but failed. All cases presented with hypotension (less than 80/60 mmHg), tachycardia (greater than 100 times/min) and with a mean hemoglobin of 9 mg% during the observation period. In these patients, blood loss, operating time and length of hospitalization was increased when compared with a group of 7 patients undergoing cesarean hysterectomy. In patients with placenta accreta, who are candidates for cesarean hysterectomy, initial hypotension, tachycardia and shock developed during cesarean section. It must be emphasized that conservative aggressive measures to control obstetric hemorrhage remain the mainstay of therapy, but emergency hysterectomy played the life-saving role with which every practitioner of obstetrics must be familiar and keep in mind.

Glucosyltransferase gene polymorphism among Streptococcus mutans strains

Genetic polymorphisms in genes coding for the glucosyltransferases were detected among Streptococcus mutans serotype c strains by Southern blot analysis with DNA probes located within the gtfB gene (H. Aoki, T. Shiroza, M. Hayakawa, S. Sato, and H. K. Kuramitsu, Infect. Immun. 53:587-594, 1986). Restriction endonucleases were used to examine genomic DNAs isolated from serotype a to h strains. The variations were readily detected among 33 strains of serotype c by EcoRI and PstI restriction enzyme digestions. Serotypes e and f, which are genetically similar to serotype c, also had comparable polymorphism; however, serotypes a, b, d, g, and h did not hybridize to the same DNA probes in parallel experiments. Further analysis of enzymatic activities for glucan synthesis and sucrose-dependent adherence revealed no significant differences among the serotype c strains. Our results suggested that genetic polymorphisms existing in S. mutans serotype c strains may reflect a complexity in genes coding for the glucosyltransferases, which are produced ubiquitously in members of the S. mutans group.

Human T-lymphotropic virus type I genome in adult T-cell leukemia/lymphoma

The proviral DNA of human T-lymphotropic virus type I (HTLV-I) was examined in 8 patients with adult T-cell leukemia/lymphoma (ATL/L) by Southern blot analysis. Judging from the number of bands containing viral DNA sequences in tumor cells, one and three copies of proviral genome were detected in 7 and 1 cases, respectively. The proviral genome in 1 case contained variant PstI sites and a single defective provirus which lost 5' LTR, gag and a part of pol genes was found in 2 cases. However, the pX region was detected in both of 2 latter cases by using the polymerase chain reaction. The results indicate that not all tumor cells from ATL/L yield infectious viruses and also support that the product of pX region may contribute to the tumorigenesis of HTLV-I.

Analysis of Epstein-Barr virus DNA in nude mouse-passaged nasopharyngeal carcinoma tissues

DNAs extracted from two series of nude mouse-passaged nasopharyngeal carcinoma (NPC) tissues, NPC-295 and -306, and P3HR1 cells were digested with restriction enzyme Bam HI, then electrophoresed on agarose gel and analysed for the Epstein-Barr virus (EBV) DNA fragments by Southern hybridization with 27 radioactive Bam HI DNA fragments and the Eco RI Dhet DNA fragment from cloned EBV DNA of B95-8 cell line. Constant hybridization patterns were revealed in these experiments and the results suggest a stable existence of EBV DNA including replicative form and episomal form in these tissues even after a long time of passage. Neither deletion in YH region nor in I region could be detected when using Bam HI Y, H and I as probes, suggesting the EBV in these tissues are "more complete" viruses. When Bam HI F was used as a probe, an extra Bam HI site was revealed in the analysis of the DNA from NPC-295 suggesting the polymorphism of DNA present in this region. Restriction maps of EBV DNAs in both nude mouse-passaged NPC tissues are proposed. The results suggest that nude mouse-passaged NPC tissue is a good model to study the structure of EBV DNA in tumor tissue.

Evolutionary conservation of target sequences for cis-acting regulation in c-myc exon 1 and its upstream region

Transcriptional control of the c-myc proto-oncogene, an important factor in cellular growth, differentiation and in the genesis of various neoplasms, is mediated by multiple positive and negative regulators in the 5' end region of the gene. Here, we report the nucleotide sequence of the first c-myc exon and its upstream region from woodchuck, a rodent which can develop liver tumors associated with c-myc activation [Möröy et al., Nature 324 (1986) 276-279]. Alignment of these sequences with the corresponding human and murine regions shows a surprisingly high homology between woodchuck and human, and suggests the absence of species-specificity in the fundamental regulatory elements which govern c-myc expression.

Integration of hepatitis virus DNA near c-myc in woodchuck hepatocellular carcinoma

A total of 33 hepatocellular carcinomas, induced in woodchucks by chronic infection with woodchuck hepatitis virus (WHV), a virus closely related to the human hepatitis B virus, were analyzed for the state of viral DNA, the expression of viral genes and of different cellular proto-oncogenes. Low levels of viral replication and presence of integrated viral forms including sequences of the enhancer element, appeared as a general rule in these tumors. Enhanced expression of one or more of the nuclear protooncogenes: c-myc, N-myc, c-fos, c-jun and jun-B was frequently observed. In two hepatomas, elevated expression and allelic alterations of c-myc were subsequent to integration of WHV DNA near the c-myc coding domain. The viral strategy for insertional activation of c-myc in these tumors appeared basically identical to that of mammalian retroviruses in T-cell lymphomas of mice and rats. Whether insertional mutagenesis of different oncogenes may be more generally linked to liver oncogenesis induced by WHV and hepatitis B viruses remains to be determined.

Molecular characterization of a cDNA clone encoding the Epstein-Barr virus (EBV) DNase

RNA from IdUrd-treated P3HR1 cells was used for the construction of a cDNA library and screened with B95-8 EBV DNA BamHI fragment B and G probes. One clone, BG9, containing a 1.7 kb cDNA insert was further studied. Complete DNA sequence analysis revealed that BG9 encompassed the B95-8 EBV DNA sequences from nucleotide 120,747 to nucleotide 122,412 and corresponded to the BGLF5 open reading frame of the EBV DNase gene. Comparison of the sequences of BG9 with that of published B95-8 EBV DNA indicated that there were 14 different bases which results in 7 amino acid residue changes. The product of in vitro transcription/translation of a subclone, pGEM-BG9, contained the EBV DNase activity and a 52 kDa protein was immunoprecipitated from the in vitro translation products using serum from a patient with nasopharyngeal carcinoma which contained a high level of anti-DNase activity. Northern hybridization of P3HR1 RNA with the BG9 probe revealed a complex pattern of transcription in this region. Subgenomic DNA fragments were then used to map these RNA species to the B95-8 EBV DNA sequence. The result of S1 nuclease analysis indicated that a DNase ORF containing transcript sized 2.0 kb is initiated at nucleotide 122,435 +/- 1 and terminated at nucleotide 120,741 of the EBV genome.

Near-infrared-to-visible image conversion using a Si liquid-crystal light valve

A real-time near IR-to-visible image converter using a Hughes silicon liquid-crystal light valve (Si LCLV) has been demonstrated. A 1.06-microm image was converted to a 0.633-microm laser wavelength. The major advantages of this near-IR-to-visible image converter are its high sensitivity, broad bandwidth, coherent- (incoherent-) to-coherent (incoherent) image conversion, up and down wavelength conversion capability, high resolution (>10(5) resolution elements), room-temperature operation, and high damage threshold.

Corynebacterium pseudotuberculosis exotoxin: fatal hemolytic anemia induced in gnotobiotic neonatal small ruminants by parenteral administration of preparations containing exotoxin

Inoculation of live Corynebacterium pseudotuberculosis, culture supernatant, ammonium sulfate-fractionated crude exotoxin, or chromatographically purified exotoxin preparations into gnotobiotic small ruminants (n = 13) caused death of the ruminants within 48 hours. Characteristic changes observed in animals living greater than or equal to 2 hours after inoculation included hemorrhage and edema at the site of injection, severe hemolytic anemia and hemoglobinuria, dark red fluid in body cavities, lung edema, and icterus. The crude exotoxin preparation caused a syndrome of acute shock in 2 lambs that died within 15 minutes after inoculation. Clinical and pathologic responses of animals inoculated with culture supernatant and purified toxin were similar. Histopathologic evidence indicated that the exotoxin caused necrotic changes in the proximal convoluted tubules of the kidneys. Inoculation with live organisms caused multiple foci of suppurative inflammation in skeletal muscle and adjacent adipose tissue, whereas such changes were not observed in animals administered exotoxin preparations. Although C pseudotuberculosis exotoxin induced a hemolytic anemia in the experimental animals, it did not lead to in vitro lysis of ovine, caprine, or bovine erythrocytes, unless they had been sensitized with Rhodococcus (Corynebacterium) equi filtrate. The toxic sphingomyelin-specific phospholipase D from C pseudotuberculosis had a molecular weight of 31,000 daltons and an isoelectric point of approximately 9.6. The elution profile of exotoxin on a carboxymethyl Sephadex column was studied and the majority of the enzymatic activity was eluted by a NaCl gradient (0.25M to 0.7M) with a maximum at 0.35M NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)

Scattering of optical surface waves by a covered groove

The reflectionjand modeconversionbehavior is considered for both TE(0) and TM(0) modes at a covered groove, which is cut in the substrate surface and covered by a thin film. With a numerical example, the scattering behavior of covered and surface grooves is presented here. It is found that a covered groove produces much less radiation loss than a surface groove of the same shape. Therefore, it is preferable as a reflector element in applications which require minimum mode conversion loss. On the other hand, surface grooves are preferable for grating couplers as they provide stronger coupling from surface to space waves as observed in this study.