Sequence analysis of the nucleocapsid protein gene of the porcine reproductive and respiratory syndrome virus Taiwan MD-001 strain

The 3'-portion of the genome from a Taiwan isolate of porcine reproductive and respiratory syndrome (PRRS) virus, strain MD-001, was cloned and sequenced. The resultant 549 nucleotides contained an open reading frame with a coding capacity of 123 amino acids (predicted Mr 13,600). The predicted protein corresponds to the nucleocapsid protein, the gene product of ORF7. Comparative sequence analysis of several known PRRSV strains indicated that this protein showed the highest degree of amino acid similarity to the US VR2332 and the Canadian IAF-Exp91 strains (92.7%) and the least to the Dutch Lelystad strain (56.5%). The phylogenic trees constructed on the basis of the known PRRSV nucleotide sequences indicated that MD-001 strain belongs to the North American strain cluster and that it is distinct from the European virus.

Recent advances in the discovery and development of flavonoids and their analogues as antitumor and anti-HIV agents

Antitumor and anti-HIV flavonoids and their analogues will be reviewed with emphasis on those discovered in our laboratory. The active antitumor compounds include the antileukemic tricin (1) and kaempferol-3-O-beta-D-glucopyranoside (2) from Wikstroemia indica, the cytotoxic hinokiflavone (3) from Rhus succedanea, the cytotoxic isoflavone (8) from Amorpha fruticosa, two dihydroxypentamethoxyflavones (9, 10) from Polanisia dodencandra. The development of synthetic 2-phenyl-4-quinolones as potent cytotoxic antimitotic flavonoid analogues and 2-phenylthiochromen-4-ones as potent antitumor flavonoid analogues will be presented. Selected results from other laboratories and antitumor-related biological studies also will be discussed. Flavonoids have also been investigated as potential anti-HIV agents. In our laboratory, acacetin-7-O-beta-D-galactopyranoside (131) from Chrysanthemum morifolium and chrysin (102), as well as apigenin-7-O-beta-D-glucopyranoside (130), from Kummerowia striata, have been found to exhibit anti-HIV activity. In other studies, some flavonoids and related compounds have been investigated as inhibitors of HIV-1 reverse transcriptase, protease, and integrase. The isolation and structural modification of such plant-derived active principles provide a continuing source of potential antitumor and anti-HIV agents.

Functional dissociation between local and systemic immune response during anti-melanoma peptide vaccination

Peptide vaccination against tumor Ags can induce powerful systemic CTL responses. However, in the majority of patients, no tumor regression is noted. To study this discrepancy, we analyzed CTL reactivity in a melanoma patient (F001) vaccinated with g209-2M peptide, a single residue variant of gp100(209-217). G209/g209-2M-reactive CTL were identified in post- but not prevaccination PBL. Limiting dilution analysis identified one predominant CTL clone (C1-35), with TCR Vbeta6s2, recognizing g209/HLA-A*0201-expressing targets. Additionally, two autologous melanoma lines (F001TU-3 and -4) and 20 separate tumor-infiltrating lymphocyte cultures were generated from a fine needle aspirate of a metastatic lesion progressing after initial response to vaccination. Both F001TU did not express gp100 and were not recognized by C1-35. Loss of gp100 by F001TU correlated with a marked reduction of gp100 expression in the same metastatic lesion compared with prevaccination. Thus, ineffectiveness of C1-35 and tumor progression could be best explained by loss of target Ag expression. Interestingly, 12 of 20 tumor-infiltrating lymphocyte cultures recognized F001TU, but none demonstrated g209/g209-2M reactivity, suggesting a functional dissociation between systemic and local immune response. This study suggests that vaccination effects must be analyzed in the target tissue, rather than in the systemic circulation alone.

Dna2 of Saccharomyces cerevisiae possesses a single-stranded DNA-specific endonuclease activity that is able to act on double-stranded DNA in the presence of ATP

To gain further insights into the biological functions of Dna2, previously known as a cellular replicative helicase in Saccharomyces cerevisiae, we examined biochemical properties of the recombinant Dna2 protein purified to homogeneity. Besides the single-stranded (ss) DNA-dependent ATPase activity as reported previously, we were able to demonstrate that ssDNA-specific endonuclease activity is intrinsically associated with Dna2. Moreover, Dna2 was capable of degrading duplex DNA in an ATP-dependent fashion. ATP and dATP, the only nucleotides hydrolyzed by Dna2, served to stimulate Dna2 to utilize duplex DNA, indicating their hydrolysis is required. Dna2 was able to unwind short duplex only under the condition where the endonuclease activity was minimized. This finding implies that Dna2 unwinds only partially the 3'-end of duplex DNA and generates a stretch of ssDNA of limited length, which is subsequently cleaved by the ssDNA-specific endonuclease activity. A point mutation at the conserved ATP-binding site of Dna2 inactivated concurrently ssDNA-dependent ATPase, ATP-dependent nuclease, and helicase activities, indicating that they all reside in Dna2 itself. By virtue of its nucleolytic activities, the Dna2 protein may function in the maintenance of chromosomal integrity, such as repair or other related process, rather than in propagation of cellular replication forks.

Synthesis and anticancer evaluation of certain gamma-aryloxymethyl-alpha-methylene-gamma-phenyl-gamma-butyrolactones

Certain gamma-aryloxymethyl-alpha-methylene-gamma-phenyl- gamma-butyrolactones were synthesized and evaluated for their anticancer activity. These compounds demonstrated a strong growth inhibitory activity against leukemia cell lines but are relatively inactive against non-small cell lung cancers and CNS cancers. The anticancer potency for aryl portion is in an order of quinoline > 8-hydroxyquinoline > 2-methylquinoline >> naphthalene >> benzene.

Synthesis and cytotoxicity of acetyl-4H,9H-naphtho[2,3-b]thiophene-4,9-diones

Several new acetyl-4H,9H-naphtho[2,3-b]thiophene-4,9-diones were synthesized and evaluated for in vitro cytotoxicity by NCI against seven cancer cell types. 2,7-Diacetyl naphtho[2,3-b]thiophene-4,9-dione (9) showed significant cytotoxicity against leukemia cells with log GI50 values of -7.61 against SR cells and -7.18 against MOLT-4 cells. 3-Acetyl-naphtho[2,3-b]thiophene-4,9-dione (6) also demonstrated potent cytotoxicity in the latter cell line with log GI50 < -8.

Long-term effect of Helicobacter pylori eradication on gastric metaplasia in patients with duodenal ulcer

There have been conflicting reports on the effect of Helicobacter pylori eradication on gastric metaplasia in the duodenal bulb (DGM). In the present study, we have investigated the relationships between DGM and H. pylori by examining whether or not H. pylori-positive patients had more DGM than H. pylori-negative patients with nonulcer dyspepsia (NUD) or duodenal ulcer (DU), and by examining the effect of eradication of H. pylori on the prevalence and the extent of DGM during the long-term up to 4 years. Fifty H. pylori-positive and seven H. pylori-negative patients with DU and 23 H. pylori-positive and 23 H. pylori-negative NUD subjects were studied. Two duodenal bulb biopsy specimens were taken for histologic evaluation and the presence and the extent of DGM were evaluated. The extent of DGM was classified as none (grade 0), focal (grade 1), multifocal (grade 2), and diffuse type (grade 4). In H. pylori-positive patients with DU, follow-up gastroscopy was conducted 4 weeks, 1 year, and 4 years after H. pylori eradication. DGM was significantly (p < 0.001) more common (DU: 93%, NUD: 22%) and significantly (p < 0.001) greater in extent for patients with DU than for NUD subjects (DU: 1.89, NUD: 0.28). Neither the prevalence nor the extent of DGM was affected by H. pylori status in patients with DU or NUD; the prevalence (extent) of DGM of H. pylori-positive and -negative patients with DU were 96% (1.94) and 71% (1.57), respectively. In the 43 "H. pylori-eradicated" group, initial prevalence of DGM was 95% and those of 4 weeks, 1 year, and 4 years after eradication were 91%, 96%, and 79%, respectively. The initial extent of DGM was 1.93, and those of 4 weeks, 1 year, and 4 years after eradication were 1.90, 1.88, and 1.57, respectively. In conclusion, the prevalence and the extent of DGM were not related to H. pylori in patients with DU or NUD. In addition, the prevalence and the extent of DGM did not change until 1 year after H. pylori eradication in patients with DU, and decreased to the initial level of the H. pylori-negative DU group but without statistical significance after 4-year follow-up.

Susceptibility of penicillin-susceptible and -resistant pneumococci to CFC-222, a new fluoroquinolone

The in-vitro activity of 12 antibacterial agents against 98 clinical isolates of Streptococcus pneumoniae, including 54 penicillin-resistant strains, was determined by a standardized broth microdilution method. CFC-222, vancomycin and imipenem were the most active agents, with an MIC90 of 0.5 mg/L for the test strains. CFC-222 was 16-fold more potent than ciprofloxacin and ofloxacin against all strains tested, including both penicillin-susceptible and -resistant strains. The anti-pneumococcal activity of fluoroquinolones was not affected by penicillin susceptibility. These results indicate that CFC-222 is potentially useful for treating infection caused by penicillin-resistant strains of S. pneumoniae.

Identification and characterization of novel antimicrobial decapeptides generated by combinatorial chemistry

Novel combinatorial libraries consisting of simplified amino acid sequences were designed to screen for peptides active against the Candida albicans membrane. A novel decapeptide, KKVVFKVKFK, that had a unique primary amino acid sequence was identified in this work. This peptide irreversibly inhibited the growth of C. albicans and showed a broad range of antibacterial activity but no hemolytic activity. Circular dichroism spectra revealed that the predominant secondary structure of this peptide strongly depended on the membrane-mimetic environments; the peptide preferred to form an amphipathic alpha-helical structure in the presence of 50% trifluoroethanol, while it preferred to adopt a distorted alpha-helical structure in the presence of sodium dodecyl sulfate micelles. Experiments in which dye was released from vesicles indicated that this novel antimicrobial peptide killed microorganisms through the action on the membrane as its primary target. Replacement of amino acids in this active decapeptide on the basis of information from the libraries could provide unique information about factors affecting its antimicrobial activity such as its secondary structure, net positive charge, and hydrophobicity.

Synthesis and antiplatelet activity of phenyl quinolones

In our search for novel antiplatelet agents, seven positional phenyl quinolone isomers were synthesized. Preliminary screening confirmed their inhibitory effects against arachidonic acid (AA)-induced platelet aggregation. Varying the substitutional position of the phenyl group had a profound effect on the antiplatelet activity of these isomers. 3-Phenyl-4-quinolone showed the greatest potency and was superior to indomethacin, although the two structures are quite different. The mechanism and pharmacological action of 3-phenyl-4-quinolone are currently under investigation.

Severe aplastic anemia induced by ticlopidine: report of two cases

Aplastic anemia is a rare side-effect associated with ticlopidine therapy. We report two cases of severe aplastic anemia developed after the use of ticlopidine. A 51-year-old woman took ticlopidine at 500 mg/day for 49 days to prevent a secondary stroke. She developed fever and dizziness within 49 days of initiating ticlopidine therapy. A 70-year-old woman was started on ticlopidine after coronary stent insertion. Fifty days after starting ticlopidine, she developed fever and dizziness. Both patients showed pancytopenia and were diagnosed as aplastic anemia which were confirmed by bone marrow examination. Both patients were hospitalized and received antibiotics, blood products and hematopoietic growth factors. Four and seven weeks after the withdrawal of ticlopidine, the hematologic parameters of each patient improved. A complete blood count should be monitored during ticlopidine therapy to check for cytopenia.

Locoregional response and increased natural killer activity after intratumoral injection of HLA-B7/beta2-microglobulin gene in patients with cancer

The purpose of this study was to assess the therapeutic potential of injecting the gene for HLA-B7/beta2-microglobulin into the subcutaneous metastatic nodules of patients who are refractory to conventional treatments. The nine patients evaluated were divided into three groups and given escalating doses of DNA (20, 40, and 100 microg of the HLA-B7 plasmid DNA/lipid complex for each group) every 2 weeks. Biopsy specimens from the treated tumor nodules of all nine patients were positive for the presence of DNA and for HLA-B7 mRNA expression. Moreover, in six of the nine patients, immunohistology of tumor biopsy samples revealed the expression of recombinant HLA-B7 protein. Also, all nine patients showed an increase in NK activity in their circulating peripheral blood lymphocytes. In two lung cancer patients, one partial and one mixed response was observed after gene transfer. These responses were confined to the treated nodules and the untreated locoregional lymph nodes; the lung masses showed no regression. Remission durations were 14 and 6 weeks, respectively, and in a total of 35 cycles no significant toxicities were observed. Immunohistologic analysis revealed an increased infiltration of CD4+ T cells, macrophages, and NK cells after therapy. In two responding cases, direct intratumoral injection of an allogeneic class I gene could elicit an antitumor response in locoregional areas, possibly through the activation of NK cells.

Structure-activity analysis of brevinin 1E amide, an antimicrobial peptide from Rana esculenta

Brevinin 1E, consisting of 24 amino acid residues, from Rana esculenta has potent antimicrobial and hemolytic activity. From a structural point of view, this peptide has a N-terminal hydrophobic region, a proline hinge region in the middle and a C-terminal loop region delineated by an intra-disulfide bridge, which is a common structural feature of antimicrobial peptides from Rana species. To investigate the structural features for antimicrobial and hemolytic activity, truncated and linearized brevinin 1E amides were synthesized and characterized. A deletion of three amino acids from the N-terminal region did not greatly affect antimicrobial activity but dramatically reduced hemolytic activity. The contribution of the intra-disulfide bridge to antimicrobial and hemolytic activity was somewhat different between brevinin 1E amide and truncated fragments. In brevinin 1E amide, the elimination of the intra-disulfide bridge did not greatly affect antimicrobial and hemolytic activity whereas the elimination of the intra-disulfide bridge in the truncated fragments did not decrease antimicrobial activity but did decrease hemolytic activity. Circular dichroism spectra and the retention time on the C18 reverse phase column revealed that the intra-disulfide bridge (i, i+6) formed an amphipathic loop which increased hydrophobicity and helped to induce the alpha-helical structure in the membrane-mimetic environment. Even though the intra-disulfide bridge and the N-terminal region were responsible for the alpha-helical structure and hydrophobicity, these two structural features were not essential for antimicrobial activity. The hemolytic activity of brevinin 1E amide and its analogs also correlated well with the retention time rather than the alpha-helicity.

Oxytocin receptor and its messenger ribonucleic acid in human leiomyoma and myometrium

OBJECTIVE

The study determined the expression of oxytocin receptor and its gene in human uterine leiomyoma compared with the adjacent myometrium.

STUDY DESIGN

Paired samples of leiomyoma and the adjacent myometrium from 20 women through the menstrual cycle, menopause, and various hormone treatments were studied. Oxytocin receptor was immunohistochemically localized with use of the specific antibody (2F8) to human oxytocin receptor. Oxytocin receptor protein was determined by Western blotting, whereas reverse transcription-polymerase chain reaction was used for oxytocin receptor messenger ribonucleic acid expression.

RESULTS

Immunohistochemistry showed positive staining in all tissues examined, relatively more intense in the myometrium than in the adjacent leiomyoma, and in tissues from the preovulatory than the postovulatory phase. Western blotting showed a single 70-kd band corresponding to the oxytocin receptor. The relative abundance of oxytocin receptor in both leiomyoma and myometrium was significantly higher during the preovulatory (n = 5) than the postovulatory (n = 5) phase (P = .034 and .05). In women receiving gonadotropin-releasing hormone agonist (n = 1) or oral contraceptives (n = 1), after the menopause (n = 2), and with irregular vaginal bleeding (n = 1), oxytocin receptor levels in leiomyoma and myometrium were unchanged but were reduced in anovulatory cycles (amenorrhea, n = 2). Reverse transcription-polymerase chain reaction showed messenger ribonucleic acid for oxytocin receptor as a 391-bp band in all leiomyomas and myometrium examined.

CONCLUSIONS

Leiomyoma and myometrium express the gene and protein for oxytocin receptor, which is probably partially regulated by ovarian sex steroids during the menstrual cycle.

Anti-AIDS agents. 30. Anti-HIV activity of oleanolic acid, pomolic acid, and structurally related triterpenoids

Oleanolic acid (1) was identified as an anti-HIV principle from several plants, including Rosa woodsii (leaves), Prosopis glandulosa (leaves and twigs), Phoradendron juniperinum (whole plant), Syzygium claviflorum (leaves), Hyptis capitata (whole plant), and Ternstromia gymnanthera (aerial part). It inhibited HIV-1 replication in acutely infected H9 cells with an EC50 value of 1.7 microg/mL, and inhibited H9 cell growth with an IC50 value of 21.8 microg/mL [therapeutic index (T. I.) 12.8]. Pomolic acid, isolated from R. woodsii and H. capitata, was also identified as an anti-HIV agent (EC50 1.4 microg/mL, T. I. 16.6). Although ursolic acid did show anti-HIV activity (EC50 2.0 microg/mL), it was slightly toxic (IC50 6.5 microg/mL, T. I. 3.3). A new triterpene (11) was also isolated from the CHCl3-soluble fraction of R. woodsii, though it showed no anti-HIV activity. The structure of 11 was determined to be 1beta-hydroxy-2-oxopomolic acid by spectral examination. Based on these results, we examined the anti-HIV activity of oleanolic acid- or pomolic acid-related triterpenes isolated from several plants. In addition, we previously demonstrated that derivatives of betulinic acid, isolated from the leaves of S. claviflorum as an anti-HIV principle, exhibited extremely potent anti-HIV activity. Accordingly, we prepared derivatives of oleanolic acid and evaluated their anti-HIV activity. Among the oleanolic acid derivatives, 18 demonstrated most potent anti-HIV activity, with an EC50 value of 0. 0005 microg/mL and a T. I. value of 22 400.

Exon-intron structure of the human PTK6 gene demonstrates that PTK6 constitutes a distinct family of non-receptor tyrosine kinase

Partial PTK6 (also known as Brk) cDNA was initially isolated by reverse transcription-PCR of normal human melanocyte mRNAs and the full-length cDNA encodes a non-receptor protein tyrosine kinase with an SH3 domain, an SH2 domain, and a kinase catalytic domain. We have cloned the human PTK6 gene by screening human genomic lambda libraries using the full-length PTK6 cDNA as probe. The human PTK6 gene consists of 8 exons encompassing 8.8 kb and all the splicing junctions followed the conserved GT/AG rule. Coding sequence of the PTK6 gene was identical to that of the cDNA cloned from T-47D, human breast tumor cell line. Although the amino acid sequence of the PTK6 polypeptide showed the strongest homology to those of the Src family members of protein tyrosine kinases, exon-intron boundaries of the PTK6 gene were quite different from those of the Src family genes, which are evolutionarily conserved. The 813-bp 5'-flanking sequence of the PTK6 gene upstream of a luciferase reporter gene conferred significant promoter activity, at approximately 60% level of the SV40 promoter, in transient expression assays into MCF-7, human breast tumor cell line. PTK6 mRNA was expressed at very high level in colon and at high levels in small intestine and prostate, and at low levels in some tested fetal tissues. These results suggest that PTK6 constitutes an evolutionarily distinct family of non-receptor protein tyrosine kinases and may function as an intracellular signal transducer in specific tissues.

Microvascular decompression and percutaneous rhizotomy in trigeminal neuralgia

We analyzed 417 patients with trigeminal neuralgia who underwent microvascular decompression (MVD; n = 146) or percutaneous procedures, i.e. radiofrequency rhizotomy (RFR; n = 235) and glycerol rhizotomy (GR; n = 36) between March 1973 and December 1996. MVD and RFR showed the highest rates of initial pain relief (MVD 96.5%; RFR 92.3%; GR 82.8%). RFR and GR had 5.1 and 3.3% rates of facial dysesthesia, respectively, and MVD had the lowest rate (0.3%). Among 9 cases (8.6%) with recurrences after MVD, 8 cases underwent RFR and all of them obtained good long-term results (7.2 years on average). We concluded that MVD is the treatment of choice for tolerant younger patients and should be recommended for patients who desire no sensory deficit. We also determined that radiofrequency rhizotomy is the procedure of choice for patients in whom MVD failed.

MRI-guided stereotactic thalamotomy for cerebral palsy patients with mixed dyskinesia

The author has performed 108 stereotactic thalamotomies using MRI (MGSTs) without ventriculography in 77 cerebral palsy (CP) patients with dyskinesia(s) from January 1992 to January 1997. The clinical results were verified in terms of improvement of major preoperative symptom and patient's (or relative's) satisfaction using pre- and postoperative video recording and simple questionnaires. The results were as follows: excellent in 12 MGSTs, good in 69 and fair in 27. Postoperative morbidity was transient in all patients except for 2. Recurrences were noted in 6 MGSTs (5.6%). There was no death. MGST is thus a beneficial procedure for reducing dyskinetic symptom(s) of CP patients.

Anti-AIDS agents. 33. Synthesis and anti-HIV activity of mono-methyl substituted 3',4'-di-O-(-)-camphanoyl-(+)-cis-khellactone (DCK) analogues

Four isomeric methyl substituted DCK analogues (2-5) were asymmetrically synthesized from different starting materials. 3-Methyl, 4-methyl, and 5-methyl-3',4'-di-O-(-)-camphanoyl-(+)-cis-khellactone (2-4) all were extremely potent against HIV-1 replication in H9 lymphocyte cells with EC50 and therapeutic index values of < 4.23 x 10(-7) microM and > 3.72 x 10(8), respectively, which are much better than those of DCK and AZT in this assay.

Identification and characterization of the antimicrobial peptide corresponding to C-terminal beta-sheet domain of tenecin 1, an antibacterial protein of larvae of Tenebrio molitor

An active fragment was identified from tenecin 1, an antibacterial protein belonging to the insect defensin family, by synthesizing the peptides corresponding to the three regions of tenecin 1. Only the fragment corresponding to the C-terminal beta-sheet domain showed activity against fungi as well as Gram-positive and Gram-negative bacteria, whereas tenecin 1, the native protein, showed activity only against Gram-positive bacteria. CD spectra indicated that each fragment in a membrane-mimetic environment might adopt a secondary structure corresponding to its region in the protein. The leakage of dye from liposomes induced by this fragment suggested that this fragment acts on the membrane of pathogens as a primary mode of action. A comparison between the structure and the activity of each fragment indicated that a net positive charge was a prerequisite factor for activity. To the best of our knowledge this is the first report in which the fragment corresponding to the beta-sheet region in antibacterial proteins, which consists of alpha-helical and beta-sheet regions, has been identified as a primary active fragment.

Inhibitors of the proteasome block the myogenic differentiation of rat L6 myoblasts

Myogenesis is characterized by membrane fusion and accumulation of muscle specific proteins. We have previously shown that nitric oxide acts as a messenger for membrane fusion. Here we show that inhibitors of the proteasome, such as lactacystin, reversibly block both the fusion of L6 myoblasts and the accumulation of muscle specific proteins, such as myosin heavy chain (MHC). The inhibitors also reversibly prevented the induction of the NF-kappaB activity, which is required for the expression of nitric oxide synthase (NOS). Moreover, the inhibition of the NF-kappaB activity occurred in parallel with that of the NOS activity upon treatment with increasing concentrations of lactacystin. While pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB, blocked both membrane fusion and accumulation of MHC, N(G)-monomethyl-L-arginine, a specific inhibitor of NOS, inhibited only the fusion. These results suggest that the proteasome plays an essential role in the regulation of myogenic differentiation through the activation of NF-kappaB and that the target of NF-kappaB for the expression of muscle specific proteins is distinct from that for myoblast fusion.

The position 4 nucleotide at the 3' end of the influenza virus neuraminidase vRNA is involved in temporal regulation of transcription and replication of neuraminidase RNAs and affects the repertoire of influenza virus surface antigens

Within the sequence motif conserved at the extreme ends of the influenza virus vRNAs, a unique natural variation, U or C, is observed at position 4 of the 3' end. To test the role of this nucleotide, two isogenic A/WSN/33 viruses, carrying either C4 or U4 nucleotide at the 3' end of the neuraminidase (NA) gene, were generated. Compared with the C4 virus, the U4 virus exhibited delayed synthesis of vRNA and stimulation of mRNA synthesis with prolonged accumulation in influenza virus-infected cells. The mRNA/ vRNA ratio was increased up to 20-fold by the C4 --> U4 substitution suggesting that the U4 nucleotide greatly stimulated transcription of the vRNA template. In isolated virion, the U4 virus had higher NA activity than the C4 virus. In MDBK cells, the U4 virus grew to lower haemagglutination (HA) titres but with higher infectivity than the C4 virus, with a corresponding increase in the ratio of p.f.u./HA units of about 10- to 40-fold. Western blot analysis of isolated virion showed that the ratio of two surface proteins, HA/NA, was greatly decreased in the U4 virus. This suggests that the position 4 nucleotide is a genetic determinant for the repertoire of surface antigens and their ratio could be changed without detrimental effects on virus growth. Results could be used to design genetically engineered influenza virus for vaccination. The observed down-regulation of transcription by C4 nucleotide is consistent with its potential role in segment-specific regulation of influenza virus gene expression, especially PB1, PB2 and PA proteins, during virus infection.

Induction of differentiation of the cultured rat mammary epithelial cells by triterpene acids

We investigated the effects of triterpene acids (TAs), ursolic acid (UA) and oleanolic acid (OA), on the induction of proliferation and differentiation of normal rat mammary epithelial cells (RMEC) or organoids cultured in Matrigel or primary culture system. To elucidate the effects, we tested their differentiation inducing activities with intercellular communication ability, cell cycle patterns, induction of apoptosis, and morphological differentiation in the three dimensional extracellular culture system. To study the changes of RMEC subpopulation in culture, the cultured cells were isolated, immunostained with peanut lectin (PNA) and anti-Thy-1.1 antibody and then analyzed with flow cytometry. Four different subpopulations, such as PNA and Thy-1.1 negative cells (B-), PNA positive cells (PNA+), Thy-1.1 positive cells (Thy-1.1+), PNA and Thy-1.1 positive cells (B+), were obtained and the size of each subpopulation was changed in culture with time in the presence of TAs. Intercellular communication was observed in culture for 7 days in TAs-treated cells, but not in culture for 4 days with scrape-loading dye transfer technique. G2/M phase cells and the number of apoptotic population were increased in TAs-treated groups in cell cycle analyses. S phase fractions were reduced and the change of G1 phase cells was not observed. The colonies with distinct multicellular structures, such as stellate, ductal, webbed, squamous, lobulo-ductal colonies, were observed in Matrigel culture and the frequencies of each colony were changed in the presence of TAs. These results suggest that UA and OA have differentiation inducing effects on rat mammary epithelial cells in primary or in Matrigel culture.

Stringent allele/epitope requirements for MART-1/Melan A immunodominance: implications for peptide-based immunotherapy

The exclusiveness of the relationship between peptide and HLA alleles, combined with their extensive polymorphism, emphasizes the need for immunization strategies based on endogenous processing of full length proteins (containing multiple epitopic determinants) for presentation to T cells. This could allow vaccination regardless of the patient's HLA phenotype, assuming that individual molecules can be efficient T cell Ags in association with various HLA alleles. An endogenous system of Ag presentation was developed using dendritic cells infected with recombinant viral vectors expressing the melanoma-associated Ag MART-1/Melan A. CD8+ T cells from melanoma patients were activated in vitro by coincubation with infected dendritic cells and tested for recognition of HLA-A-matched melanoma targets. This allowed the analysis of T cell induction in association with any HLA-A allele of a given patient's phenotype. In this system, MART-1/Melan A could not efficiently immunize in association with HLA-A alleles other than A*0201, including the one residue variant from A*0201: HLA-A*0226. Clonal analysis of MART-1/Melan A-specific CTL confirmed that MART-1/Melan A immunodominance is strongly restricted to the AAGIGILTV/HLA-A*0201 combination. The stringent epitope/allele requirements for MART-1/Melan A/TCR interactions were not associated with limitations in the TCR repertoire. In conclusion, autologous induction of MART-1/Melan A CTL by whole Ag processing and presentation is restricted to a unique allele/ligand combination and is excluded by minimal changes in HLA structure. Thus, whole protein vaccination for small m.w. Ags may provide no further advantage over a peptide-based approach.

Determination of cadmium and lead in urine by electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry

Electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry (ETV-ID-ICP-MS) was applied to the determination of Cd and Pb in urine samples. The isotope ratios for each element in each analytical run were calculated from the peak areas of each isotope. A relatively low vaporization temperature was used, which separated the analyte from the major matrix components and improved the ion signals of Cd and Pb significantly. Various chemical modifiers were tested to obtain the best signal of Cd and Pb. After preliminary studies, 1% HNO3 was added to the samples as the chemical modifier. The ETV-ID-ICP-MS method was applied to the determination of Cd and Pb in freeze-dried urine reference material NIST SRM 2670 and several fresh urine samples. The results for NIST SRM 2670 agreed satisfactorily with the certified values. The results for other samples obtained by isotope dilution and the method of standard additions agreed satisfactorily. The detection limits were 0.02 and 0.005 ng ml-1 for Cd and Pb, respectively. The precision between sample replicates was better than 11% for all determinations.