Epstein-Barr virus (EBV) variant with a 30-bp deletion at the carboxyl terminus (amino acids 346-355) of latent membrane protein-1 (LMP1) gene is able to transform cells and evade immune surveillance

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Mutation of a highly conserved aspartate residue in the second transmembrane domain of the cannabinoid receptors, CB1 and CB2, disrupts G-protein coupling

The cannabinoid receptors, CB1 and CB2, are members of the G-protein coupled receptor family and share many of this family's structural features. A highly conserved aspartic acid residue in the second transmembrane domain of G-protein coupled receptors has been shown for many of these receptors to be functionally important for agonist binding and/or G-protein coupling. To determine whether this residue is involved in cannabinoid receptor function, we used site-directed mutagenesis of receptor cDNA followed by expression of the mutant receptor in HEK 293 cells. Aspartate 163 (in CB1) and aspartate 80 (in CB2) were substituted with either asparagine or glutamate. Stably transfected cell lines were tested for radioligand binding and inhibition of cAMP accumulation. Binding of the cannabinoid receptor agonist [3H]CP-55,940 was not affected by either mutation in either the CB1 or CB2 receptor, nor were the affinities of anandamide or (-)-delta 9-tetrahydrocannabinol. Binding of the CB1-selective receptor antagonist SR141716A also was unaltered. However, the affinity of WIN 55,212-2 was attenuated significantly in the CB1, but not the CB2, mutant receptors. Studies examining inhibition of cAMP accumulation showed reduced effects of cannabinoid agonists in the mutated receptors. Our data suggest that this aspartate residue is not generally important for ligand recognition in the cannabinoid receptors; however, it is required for communication with G proteins and signal transduction.

Augmentation of hematopoiesis by fibroblast-mediated interleukin-6 gene therapy in mice with chemotherapy

Murine fibroblast NIH3T3 cells engineered to secrete interleukin-6 (NIH3T3-IL-6) were implanted intraperitoneally into mice and observed for their hematopoietic effects with or without 5-fluorouracil (5-FU) administration. In normal mice, the platelet and neutrophil counts in peripheral blood increased significantly after implantation of NIH3T3-IL-6 cells, but the total white blood cell numbers showed no obvious elevation. The granulocyte-macrophage colony-forming unit (CFU-GM) and megakaryocyte colony-forming unit (CFU-MK) numbers formed by stem cells in bone marrow and spleen were also found to be significantly increased after implantation of NIH3T3-IL-6 cells when compared with those in mice after implantation of NIH3T3 cells transduced with neomycin gene (NIH3T3-Neo). To observe the protective effects of NIH3T3-IL-6 cells on hematopoietic depression in chemotherapy-treated mice, the mice were preinjected with 5-FU at a dosage of 150 mg/kg before implantation of NIH3T3-IL-6 cells. The platelet and neutrophil counts showed accelerated recovery after implantation of NIH3T3-IL-6 cells. The numbers of CFU-GM and CFU-MK in bone marrow and spleen were also found to be markedly increased in hematopoietic-depressed mice when compared with those in mice implanted with NIH3T3-Neo cells. These data suggest that fibroblast-mediated IL-6 gene therapy, which can augment hematopoiesis in mice with or without chemotherapy, will be of great help in the recovery from hematopoietic depression after chemotherapy.

[The effect of c-myc antisense oligodeoxynucleotides on proliferation of pulmonary arterial smooth muscle cells stimulated by hypoxic endothelial cells conditioned medium]

OBJECTIVE

To study the effect of c-myc antisense oligodeoxynucleotides on proliferation of pulmonary arterial smooth muscle cells (SMC) stimulated by hypoxic endothelial cells conditioned medium (HECCM).

METHOD

After pulmonary arterial SMC were stimulated by HECCM, Northern blot technique was used for detection of expression of c-myc, and 3H-TdR incorporation and cell growth assay for detection of proliferation of SMC.

RESULT

HECCM promoted the expression of c-myc and proliferation of SMC significantly. Antisense-ODNs significantly inhibited the expression of c-myc and proliferation of SMC stimulated by HECCM, whereas sense ODNs didn't affect the expression of c-myc and proliferation of SMC.

CONCLUSION

HECCM promote the proliferation of SMC by increasing the expression of c-myc, antisense ODNs inhibits the proliferation of SMC by downregulating the expression of c-myc gene.

Accelerated recovery of irradiation-induced bone marrow depression by fibroblast-mediated interleukin 6 gene therapy in combination with bone marrow transplantation in mice

BACKGROUND

Both fibroblast-mediated cytokine gene therapy and bone marrow transplantation (BMT) have proven to be efficient protocols for the recovery of bone marrow depression. In this report, the effects of fibroblast-mediated interleukin (IL)-6 gene therapy, in combination with BMT, on the recovery of irradiation-induced bone marrow depression were investigated.

METHODS

NIH3T3 fibroblast cells engineered to secrete IL-6 (NIH3T3-IL-6) or NIH3T3 cells transduced with the neomycin gene (NIH3T3-Neo), in combination with 10(7), 10(6), or 10(5) syngeneic bone marrow cells, were implanted into irradiated mice.

RESULTS

The platelets and white blood cells in the peripheral blood of the irradiated mice increased greatly 12 days after implantation of NIH3T3-IL-6 cells and BMT, the white blood cell counts were restored to a normal level 32 days after the combined therapy, and the platelet number was obviously higher than that in mice implanted with NIH3T3-Neo and BMT. Twenty and 25 days after the combined therapy, the mice showed accelerated recovery of colony-forming unit (CFU)-granulocyte/macrophages and CFU-megakaryocytes when compared with the mice implanted with NIH3T3-Neo cells and BMT. Ten days after lethal irradiation with gamma rays, the spleens formed more CFU-spleen in mice implanted with NIH3T3-IL-6 cells and BMT than in mice injected with phosphate-buffered saline or NIH3T3-Neo cells. Combined therapy with NIH3T3-IL-6 cell implantation and BMT delayed the survival period of the hematopoietic-depressed mice significantly when compared with therapy with NIH3T3-Neo cell implantation and BMT.

CONCLUSIONS

These data demonstrated that the combined therapy of fibroblast-mediated IL-6 gene therapy and BMT could significantly promote the recovery of irradiation-induced hematopoietic depression.

Epstein-Barr virus (EBV) in endemic Burkitt's lymphoma: molecular analysis of primary tumor tissue

Many aspects of Epstein-Barr virus (EBV) and tumor biology have been studied in Burkitt's lymphoma (BL)-derived cell lines. However, in tissue culture, patterns of gene expression and CpG [corrected] methylation often change and viral strain selection may occur. In this report, 10 cases of snap-frozen endemic BL tumors are characterized in terms of viral gene expression, promoter usage, methylation, and viral strain. EBNA1 and BamHI-A rightward transcripts (BART) were detected in 7 of 7 and LMP2A transcripts in 5 of 7 tumors with well-preserved RNA. Transcripts for the other EBNAs and for LMP1 were not detected in any tumor. These tumors differ from BL cell lines in that they lack a variety of lytic cycle transcripts. This pattern of viral gene expression in endemic BL is similar to that reported in peripheral blood mononuclear cells (PBMCs) from healthy EBV-seropositive individuals. EBNA1 transcripts originated from the Q promoter (Qp) but not C, W, or F promoters that drive transcription of EBNA1 in other circumstances. Whereas Cp has been previously shown to be entirely CpG methylated in BL, bisulfite genomic sequencing showed virtually no methylation in Qp. Type-A EBV was detected in 6 of 10 and type B in 4 of 10 cases. A previously reported 30bp deletion variant in the carboxyl terminal of LMP1 gene was detected in 5 of 10 cases. The association with both A and B strains contrasts with EBV-associated Hodgkin's disease, nasopharyngeal carcinoma, and post-transplant lymphoproliferative disease, which are much more consistently associated with A strain virus.

[Cloning and sequencing of E2/NS1 gene from a Chinese genotype III isolate of hepatitis C virus]

OBJECTIVE

To clone E2/NS1 gene from a Chinese genotype III isolate of hepatitis C virus into mammalian expression vector and analyze its primary nucleotide structure.

METHODS

Reverse transcription nested-PCR methods were employed for amplification E2/NS1 gene which was cloned into mammalian expression vector pcDNA3 by directed clone. Sequence of inserted gene was analyzed by Sanger's method.

RESULTS

E2/NS1 gene from a Chinese genotype III isolate of hepatitis C virus was cloned into eukaroytic expression vector effectively. Sequence of E2/NS1 showed 88.37% identity in nucleotide and 89.29% in putative amino acid to that of a Japanese genotype III isolate of hepatitis C virus. Nevertheless it showed 70.69% and 75.55% identity to that of a Chinese genotype II isolate of hepatitis C virus.

CONCLUSION

E2/NS1 gene from a Chinese genotype III isolate of hepatitis C virus was successfully cloned into mammalian expression vector by technique of DNA recombination. Sequence analysis showed that E2/NS1 gene has good homology intra-genotype and poor homology intergenotype of hepatitis C virus. Research of primary nucleotide structure of different genotype hepatitis C virus might be helpful for the development of vaccine against the virus.

Genetic variability and characterization of non-structural region 5 of hepatitis C virus genome from Chinese patients

Sequence variation in the putative non-structural region 5b (NS5b) of hepatitis C virus (HCV) was analyzed in China. Complementary DNA fragments from sera of 49 Chinese patients were amplified by polymerase chain reaction (PCR) and the products were cloned and sequenced. Based on the comparison in NS5b of 33 clones of genotype 1b and 16 clones of genotype 2a, Chinese isolates of HCV belong to the same subtype as HCV-J, and HC-J6 from Japan. There does exist, however, some heterogeneity in the primary structure of the nucleotide acid. Higher homology was found among Chinese isolates than among Chinese isolates and Japanese isolates. Furthermore, among Chinese isolates, we found some conserved nucleotide acid positions different from those of Japanese isolates. Comparison of average homology among the 33 clones of genotype 1b and the 16 clones of genotype 2a indicated that the average homology among genotype 2a was lower than that among genotype 1b. In addition, a deletion of three nucleotide acids and a frame-shift, resulting in the introduction of an in-frame stop codon, were first observed in the NS5b region. These results indicated geographical differences in the distribution of individual HCV isolates, and the existence of a local variant in the same subtype. Our findings also suggested the need for further study on the sequence of genotype 2a, to improve diagnosis and help to advance the development of a vaccine.

[Studies on multiple infection with hepatitis B, C and G viruses]

OBJECTIVE

To study if there exists superinfection and multiple infection in the patients with hepatitis G virus (HCV) infection.

METHODS

Reverse transcription polymerase chain reaction (RT-PCR) technique in non-structural gene 3 (NS3) region of HGV was used to detect HGV RNA in serially diluted quality control sera and HGV-C reference panel of samples provided by Abbott Co. Ltd, in 90 cases with positive hepatitis C virus (HCV) RNA, and 12 blood donors with super-infection of hepatitis B virus (HBV) and hepatitis C virus (HCV).

RESULTS

Serially diluted quality control sera showed positive for HGV RNA at dilutions of 10(-1) to 10(-5), but negative at dilutions of 10(-6) to 10(-8). HGV RNA was positive in two samples of HGV-C serum provided by Abbott Co. HGV RNA was positive in eight of the 90 cases with positive HCV RNA and in four of the 12 cases with super-infection with HCV and HBV.

CONCLUSION

There are not only super-infection of HBV and HCV, but also multiple infection.

Documenting the need for transition services at an earlier age

Though the reconciliation between the US Senate and House of Representatives on reauthorization of the Individuals with Disabilities Education Act Amendments (IDEA) was not successful in 1996, one area of agreement was the lowering of the age to begin transition services planning to 14. The current study provides documentation in support of this policy change. The enrollment records over a 5-year period of more than 7000 students were examined in Delaware public schools for the Class of 1995 to determine whether the exiting rates were different for students with and without a disability. Results indicate that students with a disability exited school at a significantly greater rate in grade 9 than their regular education peers; exited at almost double the rate in grade 10; and continued to exit at an alarming rate even in grade 12. Thus the need to begin effective transition services planning at age 14 or earlier is supported by this study of longitudinal data.

Autoantibodies and anti-interferon antibody in patients with chronic viral hepatitis and its clinical significance: a preliminary investigation

OBJECTIVE

To determine the antoantibodies and anti-interferon antibody in chronic viral hepatitis patients treated with interferon and the relation of the antibodies to the curative effect of interferon.

METHODS

Forty chronic viral hepatitis patients (twenty cases for hepatitis B; twenty patients for hepatitis C) were studied. Indirect immunofluorescence assay (IFA) was used to measure the autoantibodies. Enzyme immunoassay (EIA) was used to measure the anti-interferon total antibody.

RESULTS

Compared with normal groups, the autoantibodies in patients increased significantly (P < 0.01), and the anti-interferon antibody in chronic hepatitis B and hepatitis C patients had an obvious difference (P < 0.05). As for the curative effect, the presence or absence of autoantibodies did not have a distinct significance in patients treated with alpha-interferon, but the patients with anti-interferon antibody before or after therapy might have a different response to alpha-interferon.

CONCLUSIONS

It was suggested that the presence of autoantibodies was not a contraindication to the use of interferon in patients with chronic viral hepatitis; the clinical significance of anti-interferon antibody should be further studied.

Primary structure and variability of partial nonstructural gene 5 region of hepatitis G virus

OBJECTIVE

To sequence partial nonstructural 5 (NS5) gene of hepatitis G virus (HGV) in the sera of Chinese patients with chronic non-A-E hepatitis or hepatitis B virus (HBV) infection.

METHODS

Total nucleic acid was extracted from the sera of 35 patients with chronic non-A-E hepatitis and 20 patients with HBV infection, then it was subjected to reverse transcriptase-nested-polymerase chain reaction (RT-nested-PCR) with primers derived from the putative nonstructural gene 5 (NS5) region of HGV. The positive PCR products (994 bp in length) were directly sequenced using the Sang's method after purification.

RESULTS

HGV RNA was detected in 1 of the 35 patients (2.9%) with chronic non-A-E hepatitis and 5 of the 20 patients (25%) with HBV infection. All the 6 positive samples were sequenced. These 6 Chinese isolates exhibited 87.21% to 93.92% nucleotide sequence identities with 3 reported isolates (GBV-C, PNF2161, R10292) over the 994 nucleotides examined, while the nucleotide homologies among the 6 isolates were 90.09% to 93.82%. And 93.61% to 98.72% homologies were found at the deduced amino acid level in comparing the 6 isolates with 3 reported ones, while 93.61% to 98.40% amino acid identities were found among the 6 isolates. In the region sequenced, there existed 16 conserved proline residues and 8 conserved cysteine residues.

CONCLUSIONS

Six isolates of HGV were obtained from different Chinese patients in this study. The partial nucleotide sequences, as well as amino acid sequences, of the putative NS5 region of HGV in Chinese patients are relatively conserved. The overall degree of nucleotide conservation (90.09% to 93.82%) among Chinese isolates may make this region of the genome suitable for the development of diagnosis reagents.

[Variation in hepatitis C virus NS 5b nucleotide sequence and its relationship with interferon treatment]

In order to investigate variation in hepatitis C virus (HCV) nonstructural 5b (NS5b) nucleotide sequence and the relationship with interferon treatment, cDNA containing in this region were obtained by reverse transcription-polymerase chain reaction from the sera of 4 HCV RNA positive asymptomatic chronic carriers and 9 chronic hepatitis C patients. The cDNA were then directly analysed by polymerase-chain-reaction-directed sequencing. Compared with three published HCV type II/1b sequences (HCV-J, HC-C2 and HCV-BDS), the homology of HCV was lower in the patients with chronic hepatitis C (93.52% +/- 2.09% average), especially in nonresponders to interferon (92.70 +/- 1.90% average), than in asymptomatic HCV carriers (95.65 +/- 2.61%). In 5 patients, HCV RNA was eliminated by interferon treatment. In the remaining 4 interferon-treated HCV survived patients there were 9-48 nucleotide substitutions in HCV mutants out of 380 nucleotides, resulting 6-20 amino acids changes out of 126 amino acids. These results suggested that NS5b region variants play an important role in maintaining persistent infection and the evolution of NS5b is associated with the effect of interferon treatment.

[Improvement of the assay for pre-S2 Ag/Ab detection and its application in different patients]

A new ELISA inhibition test for measuring serum Pre-S2Ab was developed to avoid the "double positive" phenomenon. One hundred and twenty samples with Pre-S2Ab negative were detected for Pre-S2Ab, the critical range for Pre-S2Ab in normal population was confirmed: a positive result was decided while the inhibition ration was over 50%, a negative result was decided while the inhibition ratio was less than 34%, and a dubious result was decided while the ratio was over 34% but less then 50%. At the same time, serum samples from sixty patients with chronic hepatitis B were detected for Pre-S2Ag and Pre-S2Ab, it showed that (1) the positive ratio of HBV DNA in patients with Pre-S2Ag positive was much higher than in patients with Pre-S2Ag negative (P < 0.01); (2) to the 46 patients with HBV DNA positive, Pre-S2Ag had a better relationship with HBV DNA than the HBeAg/Ab did (P < 0.01). Furthermore, to patients with acute hepatitis B, the presence of Pre-S2Ab was closely related to the prognosis of the disease, and the Pre-S2Ab assay could also be used to evaluate the preventive effect of HB vaccine containing Pre-S2Ag.

[Primary structure and variability of partial sequences in nonstructural gene 5 region of hepatitis G virus]

OBJECTIVE

To sequence partial genome of hepatitis G virus (HGV) in the sera of patients with different chronic liver disease and paid donors.

METHODS

Total nucleic acids were extracted from the sera of 3 paid donors, 2 patients with liver cirrhosis, and 1 patient with non-A-E chronic hepatitis, then subjected to reverse transcriptase-nested-polymerase chain reaction (PCR) with primers derived from the putative nonstructural gene 5 (NS5). PCR products were directly sequenced after purification.

RESULTS

Partial HGV NS5 gene of 6 isolates exhibited 87.2% to 93.9% nucleotide sequence identities with 3 reported HGV isolates (GBV-C, PNF2161, R10291) while the nucleotide homologies among the 6 isolates were 90.1% to 93.8%. And 93.6% to 98.7 homolies were found at the deduced amino acid level when comparing the 6 isolates with 3 reported ones, while 93.61% to 98.40% amino acid identities were found among 6 isolates. In the region sequenced, there were 16 conserved proline residues and 8 conserved cysteine residues.

CONCLUSIONS

Six isolates of HGV were obtained from different cases and donors. The partial nucleotide sequences, as well as amino acid sequences, of the putative NS5 region of HGV were relatively conserved. This region of the genome may be suitable for the development of diagnosis reagents.

Isolation and expression of a mouse CB1 cannabinoid receptor gene. Comparison of binding properties with those of native CB1 receptors in mouse brain and N18TG2 neuroblastoma cells

The predominant animal model in which the pharmacology of cannabinoids is studied is the mouse. Nonetheless, the structure and functional expression of the mouse cannabinoid receptor (CB1) gene have not been reported. We have cloned and expressed the gene for the mouse CB1 receptor and compared its properties with those of native mouse CB1 receptors in brain and N18TG2 neuroblastoma cells. The mouse CB1 gene was isolated from a mouse 129 strain genomic library. Sequence analysis of a 6-kb BamHI fragment of the mouse CB1 genomic clone indicates 95% nucleic acid identity between mouse and rat (99.5% amino acid identity) and 90% nucleic acid identity (97% amino acid identity) between mouse and human. Examination of the 5' untranslated sequence of the mouse CB1 genomic clone revealed a splice junction site approximately 60 bp upstream from the translation start site, indicating the possibility of splice variants of the CB1 receptors. The coding region of the mouse CB1 receptor was stably expressed in 293 cells, and binding by [3H]SR 141716A and [3H]CP-55,940 was determined. The Bmax and Kd values obtained with [3H]SR 141716A (921 +/- 58 fmol/mg and 0.73 +/- 0.13 nM, respectively) were similar to those of native mouse CB1 receptors in brain (Bmax of 1.81 +/- 0.44 pmol/mg, Kd of 0.16 +/- 0.01 nM) and N18TG2 cells (Bmax of 197 +/- 29 fmol/mg, Kd of 0.182 +/- 0.08 nM). The mouse CB1 receptor genomic clone will be a useful tool for studying the function and regulation of the CB1 receptor in mice.

Nasal NK- and T-cell lymphomas share the same type of Epstein-Barr virus latency as nasopharyngeal carcinoma and Hodgkin's disease

Nasal T/NK-cell lymphomas can be further separated into those of natural killer (NK) cell lineage or of T-cell lineage, with differences in cellular phenotype, T-cell receptor (TcR) gene rearrangement and TcR transcript expression. Both NK- and T-cell subtypes are closely associated with Epstein-Barr virus (EBV). In this study, EBV gene expression was determined in 23 cases of nasal lymphoma (NL) by in situ hybridisation (ISH), reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry (IH). Of the 23 cases, 19 were classified as NK-cell and 4 as T-cell tumours. ISH for EBV-encoded small non-polyadenylated RNAs showed that all cases, whether NK or T, harboured EBV in virtually all tumour cells. RT-PCR demonstrated that NL of both subtypes expressed EBNAI of the QUK splice pattern, the latent membrane proteins, LMP1 and 2 and the BamHI A rightward transcripts in the absence of EBNA2 mRNAs, compatible with the latency type II pattern. In addition, analysis of EBV protein expression by IH revealed a heterogeneous pattern of EBV gene expression at the single-cell level consisting of both LMP1+ and LMP1- tumour cells, suggesting a mixture of latency I and II. Although 2 early lytic transcripts, BZLF1 and BHRF1, were also detected in 13 and 10 cases, respectively, the lack of ZEBRA staining in any case indicates that these lytic transcripts are most likely expressed by rare cells in the biopsies entering lytic cycle. The viral transcriptional pattern similar to that of nasopharyngeal carcinoma and Hodgkin's disease suggests that EBV can exploit common regulatory mechanisms for gene transcription in diverse host cell types. Down-regulation of immunogenic proteins (EBNA2-EBNA6) in nasal lymphoma may enable tumour cells to evade host cytotoxic T-cell surveillance.

Detection of Epstein-Barr virus-infected mucosal lymphocytes in nasal polyps

Primary nasal lymphomas of T or NK cell origin are known to be associated with Epstein-Barr virus (EBV). However, it is not known whether EBV is normally present in nasal mucosa as distinct to nasopharyngeal tissue. This study investigates the prevalence of EBV infection in 13 cases of nasal polyps. EBV DNA was detected in 2 of 13 (15%) by Southern blot hybridization and in 9 of 13 (69%) by polymerase chain reaction. In situ hybridization for EBV-encoded small nuclear RNAs (EBER) was positive in 11 of 13 (85%) cases; the virus was present in stromal lymphocytes only and not in the epithelial cells. Immunohistochemistry for EBV proteins in 7 cases revealed EBV nuclear antigen (EBNA)-2, latent membrane protein (LMP)-1, and ZEBRA (the switch protein encoded by gene BZLF1) expression in rare isolated stromal lymphocytes in 3 cases. Double immunostaining in 1 case showed that the LMP-1+ cells were B or T cells. Immunohistochemistry for EBV lytic proteins showed very rare viral capsid antigen (VCA)+ and membrane antigen (MA)+ cells in 1 case and very rare diffuse early antigen (EA-D)+ and VCA+ cells in 1 other case. The expression of ZEBRA, EA-D, VCA, and MA suggested a disruption of latency in very rare stromal lymphocytes leading to a productive cycle. Although the incidence of EBV positivity in nasal polyps in our population is high (85%), very low numbers of EBV+ cells are found in each case. Nevertheless, they indicate that nasal mucosa could be one of the sites of EBV persistence through a low level of infection of the resident lymphocytes and thereby provide a possible setting for the emergence of virally associated tumors in this site.

[Establishment of labeled primer reverse transcription in situ polymerase chain reaction and detection of hepatitis C virus in liver tissues]

OBJECTIVES

To establish bio-11-photosoralen (BP) labeled primer reverse transcription in situ polymerase chain reaction (RT-in situ PCR), and detect the location and distribution of hepatitis C virus in 17 cases liver tissue embedded by paraffin.

METHODS

The method was compared with indirect RT-in situ PCR and in situ hybridization for detecting hepatitis C virus (HCV) RNA.

RESULTS

The results of serum HCV PCR and southern blot showed that BP labeled primer PCR not only is possible, but also has a good specialty. The HCV positive rate was 59% (10/17) by indirect RT-in situ PCR, 53% (9/17) positive specimens were found by BP labeled primer RT-in situ PCR. Statistical analysis revealed that chi 2 volume was 0.12, P > 0.05, the two methods had no dominantl differences. Meanwhile only 24% (4/17) positive signals were seen by in situ hybridization, which was lower than two RT-in situ PCR, chi 2 volume was 3.97 and 4.37 respectively, P < 0.05. Moreover, HCV was mainly located in hepato-plasmas, but positive signals were found in monocytes and cholangiolar epithelia.

CONCLUSIONS

We conclude that both indirect RT-in situ PCR and BP labeled RT-in situ PCR have the good sensitivities and specialties for detecting HCV RNA of liver tissues, and HCV RNA locates not only in hepatocytes, but also in monocytes and cholangiolar epithelia. The results suggested that hepatocytes may be not only replicate location of hepatitis C virus.

Enhanced efficacy of combination of IL-2 gene and IL-6 gene-transfected tumor cells in the treatment of established metastatic tumors

IL-2 and IL-6 are important cytokines which have potent antitumor effects and can cooperate to induce immune responses more effectively. IL-2 gene or IL-6 gene-transfected tumor cells exhibited reduced tumorigenicity and decreased metastatic potential. In order to increase the therapeutic efficacy of IL-2 gene-, IL-6 gene-modified tumor vaccines, the experimental pulmonary metastatic melanoma-bearing mice were treated with inactivated IL-2 gene-transfected tumor cells and inactivated IL-6 gene-transfected tumor cells. After the combined vaccination, the pulmonary metastases were reduced more significantly and the survival time of tumor-bearing mice was also markedly prolonged. The CTL activity, NK activity and IL-2-induced LAK activity, IL-2 and TNF secretion from the splenocytes of the above tumor-bearing mice increased more significantly than that of tumor-bearing mice vaccinated with IL-2 gene-transfected vaccine or IL-6 gene transfected vaccine alone. These results demonstrated that the combined use of IL-2 gene-transfected tumor vaccine and IL-6 gene-transfected tumor vaccine could achieve more potent antitumor effect via more effective activation of specific and non-specific antitumor immune responses.

Calcium-activated potassium current in cultured rabbit retinal pigment epithelial cells

Calcium-activated potassium current was studied in cultured rabbit retinal pigment epithelial (RPE) cells using whole-cell and single channel patch-clamp recording techniques. When K+ was the principal cation in the electrode, depolarizing voltage steps from a holding potential of -60 mV activated outwardly rectifying current. Outward K+ current was increased by the Ca2+ ionophore ionomycin and reduced when the extracellular Ca2+ concentration was decreased from 2.5 mM to 100 nM in the presence of ionomycin. Outward K+ current recorded in the presence of ionomycin was blocked by iberiotoxin and by charybdotoxin. Single channel recording from cell-attached and excised membrane patches revealed a large conductance Ca2+-activated K+ (K(Ca)) channel. Identification of K(Ca) channels was based on: 1) the voltage-dependence of channel opening; 2) the large unitary conductance (> 200 pS with symmetrical 130 mM K+); 3) the dependence of the reversal potential on the K+ gradient; and 4) increased channel opening after exposure of the cytosolic surface of excised membrane patches to elevated Ca2+. These results demonstrate that Ca2+-activated K+ channels are present in rabbit RPE cells and may play an essential role in the regulation of membrane potential and ion transport.

[Detection of hepatitis C virus RNA in paraffin embedded liver tissues by in situ PCR]

The new technique of in situ polymerase chain reaction (ISPCR) was used to study hepatitis C virus (HCV). ISPCR and in situ hybridization (ISH) were performed to detect HCV in 7 paraffin embedded liver tissues and 8 para-hepatocellular cancer tissues. The positive rates were 6/7 and 4/8 respectively, significantly higher than results obtained by ISH, which were 3/7 and 1/8 respectively. It also demonstrated that the specificity of ISPCR was better than ISH. HCV RNA was not only found in hepatocyte plasma but also in cholangiolar epithelia and monocytes. We conclude that ISPCR is a sensitive and specific method that can improve the accuracy in diagnosis of HCV.

Cannabinoid receptor down-regulation without alteration of the inhibitory effect of CP 55,940 on adenylyl cyclase in the cerebellum of CP 55,940-tolerant mice

The objective of this study was to determine whether the development of tolerance to CP 55,940, a potent cannabinoid agonist, was due to changes in the receptor or second messenger system. ICR mice treated with CP 55,940 (2 mg/kg) twice a day for 6 and one-half days developed a high degree of tolerance to the pharmacological effects of CP 55,940. The ability of CP 55,940 to produce motor hypoactivity, hypothermia and immobility was reduced 163-, 97- and 19-fold, respectively. Evaluation of 3H-CP 55,940 binding to rat brain membranes indicated no difference in receptor affinity between the vehicle- and CP 55,940-treated animals. However, these binding studies revealed a 50% decrease in receptor number in the cerebellum of the CP 55,940-tolerant mice. Although cAMP is generally considered to be the second messenger for cannabinoid receptors, little difference was observed in the inhibitory effects of CP 55,940 on adenylyl cyclase activity in cerebellum between vehicle and drug-treated mice. However, there was an increase in receptor mRNA which suggests a compensation for receptor loss. There are several possible explanation for these results. There may be sufficient spare receptors such that CP 55,940-tolerant mice are capable of producing a maximal effect on the second messenger system. On the other hand, one could conclude that cannabinoid receptor down-regulation does not account for the development of tolerance to all of the effects of CP 55,940 in mice.

Induction of antitumor immunity and treatment of preestablished tumor by interleukin-6-gene-transfected melanoma cells combined with low-dose interleukin-2

Transfer of cytokine genes into tumor cells has proven a valuable approach for cancer treatment. In order to generate a more effective cancer vaccine, we transfected the human interleukin-6 (IL-6) gene into B16 melanoma cells. A B16 cell clone secreting the highest level of IL-6 was obtained by G418-resistant selection, limiting dilution and IL-6 assay. The IL-6-gene-transfected tumor cells exhibited in vitro growth inhibition, reduced tumorigenicity and decreased metastatic competence. After immunization with the inactivated IL-6-gene-transfected vaccine, the murine cytotoxic T lymphocyte activity, natural killer activity and lymphokine-activated killer activity increased markedly. After treatment with the vaccine, the tumor-bearing mice showed significant growth inhibition of subcutaneous tumor, reduction in pulmonary metastases and extension of survival time. The above therapeutic effect was better when low-dose IL-2 was administered simultaneously, although this dosage of IL-2 had no in vivo antitumor effect. These data demonstrated that IL-6-gene-transfected cancer vaccine has a potent antitumor effect via efficient induction of antitumor immunity, and a better therapeutic effect could be achieved when the vaccine is combined with low-dose IL-2 as adjuvant.

[Antitumor effect of interleukin-2 gene-transfected tumor vaccine in combination with interleukin-6 gene-transfected tumor vaccine]

It has been shown that IL-2 and IL-6 can cooperate to induce immune responses more effectively. In order to increase the therapeutic efficacy of cytokine gene-transfected tumor vaccines, we treated the experimental pulmonary metastatic melanoma-bearing mice with IL-2 gene-transfected tumor vaccine and IL-6 gene-transfected tumor vaccine. After the combined treatment, the pulmonary metastases were reduced more significantly and the survival time of tumor-bearing mice was also prolonged more significantly. The CTL activity, NK activity and IL-2-induced LAK activity, IL-2 and TNF secretion from the splenocytes of the above tumor-bearing mice increased more significantly than that of tumor-bearing mice treated with IL-2 gene-transfected vaccine or IL-6 gene-transfected vaccine alone. These results demonstrated that the combined use of IL-2 gene-transfected tumor vaccine and IL-6 gene-transfected tumor vaccine could achieve more potent antitumor effect via more efficient activation of immune functions. The experiment outlines a novel approach to the cytokine gene therapy of cancer.

[Enhanced immune functions and antitumor activity of fibroblast-mediated interleukin-2 gene therapy]

The aim of the present study was to establish fibroblastmediated IL-2 gene therapy and to observe its antitumor effect in the mouse tumor model. The IL-2 gene-transfected fibroblasts (NIH3T3-IL-2+) secreting high level of IL-2 were encapsulated with collagen and then implanted i.p. into mice. Certain level of IL-2 could be detected in murine serum for some periods, and the splenic proliferation, NK and LAK activities, cytokine production (IFN-v, TNF, IL-2) were enhanced significantly. It was of great importance that the high endogenous LAK activity was induced. The significant therapeutic effect of i.p. implantation of NIH3T3-IL-2+ on ascitic liver carcinoma-bearing mice was observed. The better therapeutic results could be achieved. NIH3T3-IL-2+ cells were i.p. implanted in combination with i.p. injection of LAK cells. These results demonstrated that fibroblast--mediated IL-2 gene therapy has potent antitumor effect via augmentation of immune functions and the antitumor effect will be more obvious when IL-2 gene therapy is used along with the adoptive transfer of LAK cells.

Characterization of a delta opioid receptor in rat pheochromocytoma cells

In one subclone of PC12 pheochromocytoma cells, PC12h, the levels of delta opioid receptors markedly increase in response to nerve growth factor (NGF). This increase, as assessed by [3H]diprenorphine binding, is found only under specific culture conditions. NGF treatment of PC12h cells also results in the induction of delta opioid receptor (DOR-1) mRNA. The time course for NGF induction of mRNA and protein is similar, although the levels of mRNA increase approximately 5-fold, whereas the levels of receptor increase only 2-fold. Competition studies with selective delta ([D-Pen2,5]-enkephalin, DPDPE), mu ([D-Ala2,N-Me-Phe4,Gly-ol5]- enkephalin, DAMGO) and kappa (trans-[+/-]-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]- benzenacetamide methansulfonate salt, U50,488) opioid agonists to displace [3H]diprenorphine confirm that the delta subtype of opioid receptor is present on PC12h cells. The delta opioid receptor is coupled functionally, as indicated by agonist inhibition of forskolin-stimulated cAMP accumulation in a naloxone-reversible manner. Finally, the delta opioid receptor was cloned from PC12h cells. The sequence was identical with that described previously for the rat clone. The PC12h cell line thus provides a model system in which to study regulation of delta opioid receptors.

Analysis of the antinociceptive actions of the kappa-opioid agonist enadoline (CI-977) in neonatal and adult rats: comparison to kappa-opioid receptor mRNA ontogeny

Earlier reports indicate that kappa-opioid agonists may be especially potent in the formalin test of tonic nociception, and that neonatal rat pups are more sensitive to mu-agonists, when compared to adults. We have assessed the potency of enadoline (CI-977), a novel and selective kappa-opioid agonist, in the formalin and tail-flick nociceptive tests in 3-day-old rat pups and compared their responses to adults in the same tests. In addition, the recent cloning of the kappa-opioid receptor has allowed us to make the first evaluation of the ontogeny of kappa-opioid receptor mRNA in an effort to elucidate a possible mechanism for differences in sensitivity to kappa-opioid agonists. Enadoline was found to be a potent antinociceptive agent in the formalin test; the neonates were eight times more sensitive than the adults. kappa-Opioid receptor mRNA, however, is present in whole brain at adult levels as early as postnatal day 3. Previous studies have shown kappa-opioid receptor levels, as measured by radioligand binding and receptor autoradiography, to be present at postnatal day 3 as well. Consequently, it is unlikely that gross differences in receptor number subserved the modest increase in sensitivity to enadoline observed in the neonates in the formalin test. Enadoline was less potent and less effective in the tail-flick test in the neonates. The adults were similarly insensitive to the antinociceptive effects of enadoline in the tail-flick test. Additional studies indicated that enadoline significantly increased locomotor activity, as assessed by the open-field test, in neonates, while decreasing activity in the adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Epstein-Barr virus is localized in the tumour cells of nasal lymphomas of NK, T or B cell type

Seven cases of nasal lymphoma were studied to identify the lineage of Epstein-Barr virus (EBV)+ cells using dual-labelling methods. Five cases were phenotypically and genotypically of natural killer cell (NK) type with germ-line configuration of T-cell receptor (TcR) beta-chain gene and immunoglobulin heavy-chain joining region (IgJH) gene, with one case each of T- and B-cell type showing rearranged TcR beta or IgJH and lambda-light chain genes respectively. EBV genome was clonal in all these cases except in the B-cell case where its clonality was undeterminable. Using in situ hybridization (ISH) for EBV-encoded small nuclear RNA 1 and 2 (EBER), signal was detected in 45% to 88% of nucleated cells in the tumours. Immunostaining for EBV latent membrane protein-I (LMP) also revealed numerous LMP+ cells in 3/5 NK-type cases and the T- and B-cell cases. Using ISH for EBER combined with immunostaining for CD markers and double immunohistochemistry for LMP and CD markers, the predominant lineage of the EBV+ cells was identified as: CD2+CD3-CD19-CD20- CD45R0 +/- CD56+CD68- in the NK-type cases, CD2+CD3 +/- CD19-CD20- CD45R0+CD56-CD68- in the T-cell case and CD20+CD45R0-CD68- in the B-cell case, in agreement with the genotype and phenotype of each tumour. These results show that, in EBV+ nasal lymphomas of NK, T- or B-cell lineage, EBV was consistently associated with the tumour-cell population and support the view that EBV serves a promoting role in the pathogenesis of different types of EBV+ nasal lymphoma.

Evidence for lytic infection by Epstein-Barr virus in mucosal lymphocytes instead of nasopharyngeal epithelial cells in normal individuals

Normal nasopharyngeal tissues from 23 individuals who died of causes unrelated to the upper respiratory system and had no evidence of Epstein-Barr virus (EBV)-related diseases were studied using in situ hybridisation (ISH) and immunohistochemistry for the detection of EBV RNA and expression of EBV proteins, respectively. ISH using 35S-labelled riboprobe for EBV EBER RNA showed occasional to a few EBER+ lymphocytes in the stroma of nasopharyngeal mucosa in 14/16 cases with available paraffin-embedded tissues. In addition, very rare intraepithelial EBER+ lymphocytes were also detected in 3/16 cases. However, in none of these cases was EBER detected in the epithelial cells. Similar results were obtained using a nonradioactive ISH method for EBER (Dako). In 3/23 cases, immunostaining using monoclonal antibodies for EBV proteins on cryostat sections showed occasional cells in the stroma expressing EBV nuclear antigen 2 (EBNA2), latent membrane protein-1 (LMP), and switch protein encoded by BZLF1 gene (ZEBRA) in two cases and only very rare LMP+ and ZEBRA+ cells in one other case. Double immunostaining combining alkaline phosphatase anti-alkaline phosphatase (APAAP) for CD markers and indirect immunofluorescence for LMP showed that the LMP+ cells were either CD19+ or less frequently CD3+, but none were CD68+. These results show that both B and T lymphocytes harbouring EBV can be found in the normal nasopharyngeal tissues. Interestingly, EBV proteins associated with lytic viral replication--diffuse early antigen (EA-D), viral capsid antigen (VCA), or membrane antigen (MA)--were also detected in rare cells in the stroma in one case, and in another case only one MA+ cell was detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation and developmental expression of a rat cDNA encoding a cysteine-rich zinc finger protein

A number of cysteine-rich proteins have recently been isolated by homology screening, differential library screens, and association with other proteins. In this report, we describe the isolation of the rat cysteine-rich protein from a rat brain library during a search for clones with homology to the delta-opioid receptor. One of the cDNAs isolated hybridized to a 1.8 kb mRNA abundantly expressed throughout the rat brain as well as in rat liver. In situ hybridization reveals a wide distribution in rat brain; in particular, abundant hybridization was detected in the hippocampus, cerebellum, habenula, reticular thalamic nucleus and interposed nucleus. Nucleotide sequence analysis of a 1403 bp cDNA clone indicated 77% identity with the cDNA for human cysteine-rich protein (hCRP), that translates into a 99% identity at the amino acid level. The predicted amino acid sequence suggests four zinc fingers, two of the C4 class and two of the C2HC class. This structural motif is characteristic of members of the LIM domain protein family. The mRNA is serum-inducible in Balb/c 3T3 cells. Additional study suggests that its expression is not induced by either NGF treatment of PC12h pheochromocytoma cells, or inflammation-induced injury in the spinal cord at up to 60 min after injury. It does appear to be developmentally expressed in rat brain, consistent with a potential role in neuronal development. The rat CRP clone will be useful for studying the function of CRPs in rodent models.

Potassium currents in cultured rabbit retinal pigment epithelial cells

Membrane potential and ionic currents were studied in cultured rabbit retinal pigment epithelial (RPE) cells using whole-cell patch clamp and perforated-patch recording techniques. RPE cells exhibited both outward and inward voltage-dependent currents and had a mean membrane capacitance of 26 +/- 12 pF (SD, n = 92). The resting membrane potential averaged -31 +/- 15 mV (n = 37), but it was as high as -60 mV in some cells. When K+ was the principal cation in the recording electrode, depolarization-activated outward currents were apparent in 91% of cells studied. Tail current analysis revealed that the outward currents were primarily K+ selective. The most frequently observed outward K+ current was a voltage- and time-dependent outward current (IK) which resembled the delayed rectifier K+ current described in other cells. IK was blocked by tetraethylammonium ions (TEA) and barium (Ba2+) and reduced by 4-aminopyridine (4-AP). In a few cells (3-4%), depolarization to -50 mV or more negative potentials evoked an outwardly rectifying K+ current (IKt) which showed more rapid inactivation at depolarized potentials. Inwardly rectifying K+ current (IKI) was also present in 41% of cells. IKI was blocked by extracellular Ba2+ or Cs+ and exhibited time-dependent decay, due to Na+ blockade, at negative potentials. We conclude that cultured rabbit RPE cells exhibit at least three voltage-dependent K+ currents. The K+ conductances reported here may provide conductive pathways important in maintaining ion and fluid homeostasis in the subretinal space.

Improved double immunohistochemical staining method for cryostat and paraffin wax sections, combining alkaline phosphatase anti-alkaline phosphatase and indirect immunofluorescence

AIMS

To develop and immunohistochemical staining method for cryostat and paraffin wax sections so that two different antigens in the same section of tissues could be detected by combining immunoenzyme and immunofluorescence techniques.

METHODS

This double immunohistochemical staining method combines alkaline phosphatase-anti-alkaline phosphatase (APAAP) using New Fuchsin as a chromogen and indirect immunofluorescence.

RESULTS

APAAP staining for one antigen of this double immunohistochemical staining method was observed under bright field conditions alternating with immunofluorescence for another antigen under ultraviolet light. The double exposed photograph of both easily identified the two signals within the same cell.

CONCLUSIONS

This double immunohistochemical staining method can overcome the disadvantages of any masking effect of the double immunoenzymatic methods and the background problems of double immunofluorescence method especially when applied to paraffin wax sections. It also permits good morphological identification of the doubly stained cells which may be of crucial importance in studies on pathology specimens.

Epstein-Barr virus (EBV)-related lymphoproliferative disorder with subsequent EBV-negative T-cell lymphoma

A 58-year-old Chinese man presented initially with generalized lymphadenopathy, and lymph-node biopsy showed disturbed architecture with preponderance of large B-blasts mixed with numerous CD8+ T lymphocytes, consistent with an acute Epstein-Barr virus (EBV) infection. Immunohistological and gene rearrangement studies confirmed the absence of clonal T or B cells. Polyclonal EBV with lytic infection was detected by Southern blot hybridization (SoBH). Expression of EBV proteins (EBNA2, LMP and ZEBRA) was detected in a proportion of cells by immunostaining. EBV-lytic proteins EA-D, VCA, MA were also detected in rare scattered cells. Double immunostaining showed that the LMP-positive cells were of B and of T phenotype: 73% CD19+, 26% CD2+, 23% CD3+, 8% CD4+, 17% CD8+. After biopsy, there was spontaneous regression of lymph-node enlargement, but lymphadenopathy recurred 8 months later, and the second lymph-node biopsy showed T-cell lymphoma, confirmed by detection of clonally rearranged T-cell-receptor beta-chain gene. However, EBV genome could not be detected in the second biopsy by SoBH, in situ hybridization for EBV-encoded EBER RNA, and immunostaining for EBNA2, LMP and ZEBRA was also negative. This case is of special interest because an EBV-negative T-cell lymphoma developed shortly after an acute episode of EBV-related lymphoproliferation, even though many EBV-positive T cells were detected during the acute episode. EBV was apparently not a direct cause of the lymphoma, but the close temporal association of the 2 lesions supports the hypothesis that EBV can act as a co-factor in lymphomagenesis.

Lack of correlation between expression of Epstein-Barr virus (EBV) latent membrane protein and bcl-2 oncoprotein in vivo

AIMS

To evaluate whether there is any correlation between the expression of Epstein-Barr virus (EBV) latent membrane protein (LMP) and oncoprotein bcl-2 in the lymph node biopsy specimens of a Chinese patient with EBV-related reactive lymphoproliferation who later developed T cell lymphoma after a short period of time.

METHODS

Immunohistochemistry, with a standard alkaline phosphatase antialkaline phosphatase (APAAP) method and New Fuchsin as a chromogen, was used for single staining of bcl-2 or LMP. Double immunostaining combining APAAP and indirect immunofluorescence was performed for dual labelling of LMP and bcl-2.

RESULTS

bcl-2 was expressed in 10-30% of cells in the first lymph node biopsy specimen (EBV-associated lymphoproliferative disorder) and 30-50% of cells in the second lymph node biopsy specimen (T cell lymphoma). LMP was expressed in the first biopsy specimen but not in the second. Double immunostaining results showed that around 78% of LMP positive cells were bcl-2 negative and 94% bcl-2 positive cells were LMP negative. Among the very small fraction of LMP and bcl-2 double positive cells, the intensity of bcl-2 staining was heterogeneous and was not always stronger than that observed in LMP negative bcl-2 positive cells.

CONCLUSIONS

The expression of bcl-2 protein is independent of LMP protein status in vivo. Several mechanisms may be involved in EBV associated lymphomagenesis, and bcl-2 induction may occur independently of LMP expression.

Molecular cloning and expression of a delta-opioid receptor from rat brain

We have isolated and characterized a rat delta-opioid receptor. The deduced amino acid sequence (372 aa) closely resembles the murine delta-opioid receptor, DOR-1. In fact, 97% of the amino acid residues are conserved between the two species, while 93% of the nucleic acid residues are identical. A 6 kb mRNA was detected in rat cortex using rat DOR-1 as a probe. When expressed in COS cells, the clone shows high-affinity opioid binding with selectivity for delta-opioids. The rat delta-opioid receptor cDNA clone will be a useful tool for studying the function of delta-opioid receptor in rats.

[Homology of Chinese, Japanese, and American strains of hepatitis C virus]

As we know, the main HCV strain in Japan (HCV-J 4) is highly diverse in sequence from the original American strain (HCV-US). By comparing the sequences of these two strains, a region, located in the 3'-terminus of the putative E gene in HCV genome, was selected for PCR amplification. In this region, the Japanese strain showed high diversity from the American strain. From 4 patients, 8 isolates with the length of 277 bp, were cloned and sequenced. The homology of these 8 clones was high, indicating that these clones were in the same strain. This strain might be the major strain in China, named HCV-CHN1 in this paper. Since there were still many varieties in these 8 clones, HCV CHN1 could be possibly divided into 3 substrains. HCV-CHN1 was also found to be similar to HCV-J 4, with nucleotide homology of 83.4-86.3%, and amino acid homology of 78.3-88.0%, but remote from HCV-US, with homologies of only 68.6-72.6% and 69.6-73.9%, respectively. These results might be of paramount significance in developing the detection method for HCV infection and in preparing HCV vaccine.

[Function of direct repeat sequences in DNA replication of hepatitis B virus]

In order to investigate the function of the direct repeat sequences (DR 1 and DR 2) in DNA replication of hepatitis B virus (HBV), the nucleotides in DR 1 and/or DR 2 were substituted by oligonucleotide site-directed mutagenesis. HepG 2 cells were transfected with tandem dimers of the mutants. The results indicate that (1) DR 1 is responsible for the synthesis of pregenome RNA or minus strand DNA. (2) The relative homogeneity between DR 2 and DR 2 is very important in the formation of long cohesive end region and the circulization of HBV DNA. (3) It is first reported that in natural infection HBV DNA has a defective replication route. It gives a 3.2 Kb linear form double strand DNA with uniform structure.