- Volume 38, Issue 3, 1978
Volume 38, Issue 3, 1978
- Announcement
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- Articles
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Interferon Action III. The Rate of Primary Transcription of Vesicular Stomatitis Virus is Inhibited by Interferon Action
More LessSUMMARYTranscription of vesicular stomatitis virus (VSV) in Vero cells was confined to the synthesis of parentally-derived mRNA (primary transcription) by the use of cycloheximide and/or a ts mutant, G41(IV), at a non-permissive temperature (40 °C). More transcripts accumulated in the presence of cycloheximide than in its absence. This so-called ‘cycloheximide effect’ results from higher rates of virus transcription sustained for longer periods of time. The rate of VSV transcription initially increases linearly for 1 to 2 h after infection. Interferon reduces this rate (≃ fourfold with 50 units/ml interferon) irrespective of the presence or absence of cycloheximide. The VSV mRNA transcripts synthesized in mock- or interferon-treated cells were equal in size and had an equivalent half-life of 17 h at 40 °C. It seems likely that once transcription is initiated in interferon-treated cells, it is completed successfully.
Since interferon reduces the rate of early VSV primary transcript synthesis to below that achieved in the presence of cycloheximide, we conclude that interferon has an effect on transcription beyond that attributable solely to protein synthesis inhibition. We postulate that interferon decreases the probability of initiating virus transcription. Virus mRNA escaping this facet of interferon action may then encounter other facets such as post-transcriptional modification and/or inhibition of translation. However, the mandatory sequence of primary transcription → primary translation for negative-strand viruses like VSV dictates that the overall inhibitory effect of interferon on translation would derive in part from this prior inhibition of transcription. Thus, to apply the term ‘primary effect’ to one particular facet of interferon action may not always be meaningful.
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Modes of Infection of Barley Protoplasts with Brome Mosaic Virus
More LessSUMMARYMesophyll protoplasts of barley were efficiently infected with brome mosaic virus (BMV) in two different ways under different conditions. Polycation-independent infection occurs at low pH in low ionic strength inoculum whereas polycation-dependent infection occurs at high pH in higher ionic strength inoculum. Optimal conditions at low pH were 20 µg/ml BMV, 0.2 µg/ml poly-l-ornithine and 0.7 m-mannitol in 0.1 mm-potassium citrate buffer, pH 5.0; about 70% of protoplasts were infected. Optimal conditions at high pH were 1 µg/ml BMV, 1 µg/ml poly-l-ornithine and 0.7 m-mannitol in 50 mm-phosphate buffer, pH 8.8; nearly 60% of protoplasts became infected. A brief contact of virus and poly-l-ornithine was essential for infection at high pH whereas it inhibited polycation independent infection at low pH. At high pH, poly-l-ornithine formed aggregates with virus. Infection of protoplasts seemed to be controlled by the strength of the positive charge on virus particles at low pH and that on the virus-poly-l-ornithine complexes at high pH.
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Isolation of Thioguanine Resistant Variants of K-BALB Cells Non-inducible for Type C Viruses by 5-Iododeoxyuridine
More LessSUMMARYClones of thioguanine resistant K-BALB mouse cells were isolated which were inducible for endogenous type C virus synthesis by cycloheximide and dexamethasone, but not 5-iododeoxyuridine. A comparison of the number of foci formed on NRK and SC-1 cells suggested that the xenotropic virus was suppressed. The variants were not defective in the incorporation of thymidine or iododeoxyuridine or deficient in thymidine kinase, but were deficient in hypoxanthine-guanine phosphoribosyltransferase and the incorporation of hypoxanthine into nucleic acid. Because these cells are blocked at some point in the expression of endogenous virus, they may prove useful in establishing the steps involved in chemical activation of virus synthesis.
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Failure of Antibody to e Antigen to Precipitate Dane Particles Containing DNA Polymerase Activity and Hepatitis B Core Antigen
More LessSUMMARYSerum samples of 67 asymptomatic carriers were tested for Dane particles by electron microscopy, and for e antigen by immunodiffusion, as well as for hepatitis B antigen-associated DNA polymerase activity, and four samples enriched with respect to Dane particles were selected. Hepatitis B antigen particles in them were separated from e antigen and concentrated by centrifugation, and the Dane-rich preparations were incubated with buffer, antibody to e antigen (anti-HBe) or antibody to hepatitis B surface antigen. After centrifugation, the supernatant was tested for DNA polymerase activity, and both supernatant and precipitate were tested for hepatitis B core antigen (HBcAg) by the immune adherence haemagglutination method after the coat of the Dane particles had been disrupted with NP-40 and 2-mercaptoethanol. It was found that anti-HBe did not precipitate Dane particles as measured by DNA polymerase activity and HBcAg. On the basis of the results obtained, it has been concluded that e antigen does not exist on the surface of hepatitis B virions.
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Reduction of Intercellular Adhesiveness of Chick Heart Cells by Herpes Simplex Viruses 1 and 2
More LessSUMMARYInfection with herpes simplex viruses type 1 or 2 prevented the aggregation of 7-day-old chick heart cells into smooth, spheroidal, spontaneously beating aggregates. Virus infection also caused a loosening of peripheral cells in aggregates formed from initially uninfected cells. Measurements of rate of attachment of labelled single heart cells to a monolayer of like cells (homotypic), to HEp-2 cells (heterotypic), or to plastic substrata (nonspecific adhesion) indicated that virus infection caused a significant but differential loss of homotypic and nonspecific adhesiveness, but no alteration in heterotypic attachment rates. These observations indicate that those cell surface changes induced by viruses which are related to cell adhesion can be quantified by techniques measuring attachment rates.
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Epstein–Barr (EB) Virus Genome-containing, EB Nuclear Antigen-negative B-lymphocyte Populations in Blood in Acute Infectious Mononucleosis
More LessSUMMARYExperiments have been performed to identify the type and size of cell infected by EB virus in the blood of acute infectious mononucleosis (IM) patients, and to investigate the nature of the infection. Virus-infected cells, recognized by their ability to give rise to lymphoblastoid cell lines when co-cultivated with foetal lymphocytes, were shown to be restricted to the B-lymphocyte population. Samples of this population from each of eight IM patients were found to be negative for EB nuclear antigen (EBNA) staining. Thereafter, fractions of IM B-lymphocytes prepared on the basis of cell size were assayed either by co-cultivation, for the incidence of virus-infected cells, or by immunofluorescence staining for the presence of cells expressing EBNA. The great majority of virus-infected cells were found in the fractions of normal sized B-lymphocytes and yet these fractions were unequivocally EBNA-negative. The finding of EB virus-infected, EBNA-negative B-cell populations in IM blood is discussed in terms of the type of infection established by EB virus in the circulation of IM patients.
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Regulation of the Synthesis of Sindbis Virus-specified RNA: Role of the Virion Core Protein
More LessSUMMARYCells infected with seven different RNA+ mutants of Sindbis virus were found to accumulate a virus-specified polypeptide of mol. wt. 144000 (p144) during incubation at the non-permissive temperature, while at the same time synthesis of the virus structural proteins was drastically reduced. Mapping of the tryptic peptides of p144 showed that it contained the amino acid sequences of all the virus structural proteins. At the non-permissive temperature cells infected with the same seven mutants (out of 28 examined) also showed increased synthesis of 26S RNA, the mRNA for the virus structural proteins, relative to 42S RNA, and the virus genome, compared with infections by wild-type virus. We propose that both these phenotypic effects are the results of a single mutational step and that the primary defect in the processing of the virus structural protein precursor induces the relatively increased rate of synthesis of structural protein mRNA. Temperature-shift experiments with mutant-infected cells showed that p144 itself is not the agent of this effect. The failure of exposure to zinc ions to alter the RNA ratio in wild-type virus-infected cells suggested that the virus envelope proteins are not involved either, since their synthesis is preferentially inhibited under these circumstances. It is possible that it is the failure to synthesize the proper quantity of core protein in the mutant-infected cells which causes the shift of RNA synthesis in favour of structural protein mRNA.
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Cytoplasmic Vacuoles of Rous Virus Transformed Cells are Organelles Involved in Cation Uptake
More LessSUMMARYCytoplasmic vacuoles induced during transformation of cells by Bryan strain Rous sarcoma virus (RSV-BH) have been studied using the cationic dye, neutral red (NR). Both the rate of uptake and the accumulation of NR are greater in RSV-BH transformed cells than non-transformed cells. However, uptake was greater in vacuolated than in non-vacuolated cells, whether or not they were transformed. The NR was incorporated into pre-existing vacuoles in the absence of cytoplasmic staining, suggesting the existence of direct channels from the cell surface to the vacuoles. Other low mol. wt. cationic dyes could also be incorporated into vacuoles, although those with branched structures or cationic weights greater than 330 were excluded. No anionic dyes were incorporated.
Infection of cells with a virus mutant, RSV-BH-Ta, induces temperature-dependent vacuolization. After a shift to the vacuole-permissive temperature, vacuoles developed at different rates and with morphological variations with different cations. Vacuoles which had formed in the presence of several cations, (K+, Rb+, tris+, choline+) failed to disappear when cells were incubated at a temperature sufficient to revert vacuoles formed in Na+-containing medium. No short-term effects of Cl− replacements (Br−, I−, or SO2- 4) on vacuolization or reversal were observed.
The results suggest that these vacuoles are organelles involved in cation uptake. A possible function for these organelles in RSV-BH induced malignancy is discussed.
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Deposition of Retrovirus Associated Antigens (p30 and gp70) on Cell Membranes of Feline and Murine Leukaemia Virus Infected Cells
More LessSUMMARYA quantitative estimation of retrovirus associated cell membrane antigens of murine and feline cells infected with their respective type C leukosis virus is presented. Using a radio-immune assay with three broadly reactive antisera, the minimum estimated number of retrovirus associated antigenic determinants on YAC [Moloney leukaemia virus (MuLV) infected murine] and FL-74 [feline leukaemia virus (FeLV) infected feline] cells was 1.3 × 106 and 1.6 × 106 determinants per cell respectively. The virus structural proteins p27–30 and gp70 were detected by three component specific antisera on murine and feline cell surfaces in amounts which varied between cell isolates. MuLV infected cells produced as many as 1.9 × 105 p30 antigenic determinants and 7.5 × 105 gp70 determinants on infected cells. FeLV infected cells (FL-74) expressed 5.6 × 105 p27 and 7.5 × 105 gp70 antigenic determinants per single cell surface. The major core protein (p27–30) and the major envelope glycoprotein (gp70) antigens are sufficiently physically separated on cell surfaces so that binding of either of the membrane antigens with component specific antibodies does not interfere with binding of antibodies specific for the other. Despite the expression of interspecies determinants for p30, gp70, and other retrovirus associated antigens detected by antibody procedures, interspecies determinants of cell mediated immunity could not be demonstrated in immune mice bearing Moloney sarcoma virus (MSV) induced tumours. Furthermore, xenogeneic immunization of mice with FL-74 cells failed to protect mice against the growth of MSV induced lymphoma or sarcoma.
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Mitogen Induction of Murine C-Type Viruses. IV. Effects of Lipoprotein E. coli, Pokeweed Mitogen and Dextran Sulphate
More LessSUMMARYLipoprotein E. coli, a B-cell mitogen, is identified as a new agent inducing the release of endogenous C-type virus from mouse spleen cells. Like lipopoly-saccharide, a previously identified inducer, this compound has a synergistic effect with 5-bromo-2′-deoxyuridine. Induced virus has the characteristic density as well as morphology of C-type viruses. Budding viruses are detected on cultured BALB/c cells by electron microscopy 2 to 4 days following culturing in the presence of lipoprotein.
Pokeweed mitogen, a compound mitogenic for T- and B-cells was negative when tested for virus induction, both alone and in combination with 5-bromo-2′-deoxyuridine. Dextran sulphate, another B-cell mitogen, was negative for induction as well. However, when, combined with lipopolysaccharide, it enhanced the virus release induced by this mitogen. In contrast, no additive effects were observed either by combining dextran sulphate with other virus amplifying mitogens or by combinations of mitogens which both have virus-inducing ability. This finding is discussed with respect to B-cell differentiation.
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An Infective Pyridoxyl-derivative of Potato Virus X: PVX-PLP
More LessSUMMARYThe reduced initial product (PVX-PLP) of the reaction of pyridoxyl 5′-phosphate (PLP) and particles of potato virus X (PVX) contains about 1 (0.6 to 1.2) molecules of PLP per protein subunit and is infective. Hydrolysates of the protein contain N-ε-pyridoxyl-lysine. PVX-PLP reacts with chlorogenoquinone to 1/4 of the extent of PVX; similarly, PVX which has reacted with chlorogenoquinone (PVX-Q1) binds only 1/3 to 1/5 as much PLP as does PVX. PVX-PLP contains two types of fluorescent subunit which can be separated by electrophoresis in SDS-acrylamide gels: one of these is fluorescent and is not degraded by brief exposure to trypsin, whereas the other is degraded to a smaller form which is also fluorescent. Tryptic digests of the protein from PVX-PLP contain at least two fluorescent peptides. It is argued that PLP reacts with two lysine ε-amino groups of PVX, one of which also reacts with chlorogenoquinone, and the other of which is recognized by trypsin.
Protein isolated from PVX reacts with up to 6 molecules of PLP. The conformation of the subunits in the intact virus apparently makes many ε-amino groups inaccessible to PLP.
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Aggregation of Enterovirus Small Plaque Variants and Polioviruses under Low Ionic Strength Conditions
A. Totsuka, K. Ohtaki and I. TagayaSUMMARYVirion aggregation in low ionic conditions was observed with small plaque variants of Coxsackievirus type B3 and Echovirus types 4 and 11 by sedimentation and filtration methods. Inclusion of salts or DEAE-dextran into the media prevented or reversed virion aggregation. The effect of pH on aggregate formation in low ionic strength solutions was also investigated with various strains of poliovirus. Type 1 Sabin strain formed aggregates even at high pH, while Mahoney strains did so only below pH 6.5. Type 2 virus, Sabin and MEF1 strains, and type 3 virus, Sabin, Saukett and Suwa strains, showed an intermediate behaviour between the two type 1 strains, except MEF1-LB strain, a clone obtained from MEF1 strain under acidic overlay, which showed little tendency to aggregate. These results were compared with the degree of the d character of the strains. Besides the effect of inhibiting virion aggregation, the inclusion of DEAE-dextran into a sucrose gradient slowed the sedimentation of some of the viruses in low ionic strength solutions.
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Involvement of Microtubules in Cytopathic Effects of Animal Viruses: Early Proteins of Adenovirus and Herpesvirus Inhibit Formation of Microtubular Paracrystals in HeLa-S3 Cells
More LessSUMMARYIn order to examine the involvement of microtubules in the virus-induced cytopathic effect (c.p.c.), the effect of virus infection on the formation of micro-tubular paracrystals (PC) induced by 10 µg/ml of vinblastine sulphate in HeLa-S3 cells was examined by phase-contrast microscopy. In poliovirus-infected cells, c.p.e. (cell rounding) and the inhibition of PC formation proceeded in parallel, starting 4 h post-infection. In Sendai virus-infected cells, however, PC formation was not inhibited even 24 h post-infection when most infected cells clearly showed c.p.e. (syncytial formation).
In adenovirus-infected cells, the inhibition of PC formation was observed 9 h before the appearance of c.p.e. Cytosine arabinoside (ara C) did not block the inhibition of PC formation in infected cells, but blocked the appearance of late c.p.e. (nuclear alteration). Cycloheximide blocked both the inhibition of PC formation and the induction of late c.p.e. These results suggest that an early protein synthesized de novo by adenovirus is required for direct or indirect inhibition of the microtubular PC formation. Furthermore, on ultraviolet (u.v.) inactivation of adenovirus both activities (induction of early c.p.e. shown by shrinkage of cytoplasm, and inhibition of PC formation) followed the same inactivation curve and were inactivated at a slower rate than viral infectivity and the activity leading to late c.p.e. The u.v. light sensitive target responsible for the induction of early c.p.e. and the inhibition of PC formation is about 20% of that for infectivity and is in accord with the genome size of the early functioning virus genes.
In herpes simplex virus (HSV)-infected cells, the inhibition of PC formation, the appearance of c.p.e. (cell rounding and disappearance of nucleoli) and the synthesis of V antigen proceeded in parallel. These three functions of HSV were not blocked in infected cells even when the de novo synthesis of virus DNA was inhibited by ara C or phosphonoacetic acid (PAA), whereas these three functions were blocked by cycloheximide, suggesting that a protein coded by the input virus genome early after infection inhibits the microtubular PC formation and is responsible for c.p.e. From the u.v. inactivation curve of HSV, it was confirmed that only one-tenth of virus genome was responsible for both activities (induction of c.p.e. and inhibition of PC formation).
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Radioimmunoassay and Some Properties of Human Antibodies to Hepatitis B Core Antigen
More LessSUMMARYA solid-phase radioimmunoassay for antibodies to hepatitis B core antigen (anti-HBc) is described. Polystyrene beads coated with anti-HBc, hepatitis B core antigen prepared from pooled sera of humans infected with hepatitis B virus (HBV) and 125I-labelled anti-HBc were used for the test.
Distinct patterns of development and changes of anti-HBc and their immunologic properties are all related to variations of other markers specific for HBV infections. Knowledge concerning the detailed features of the immune response to hepatitis B core antigen may provide deeper insight into the pathogenesis of HBV infections.
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Antigens of Hepatitis B Virus: Failure to Detect HBeAg on the Surfaces of HBsAg Forms
More LessSUMMARYThe particulate forms of HBsAg were analysed for the presence of HBeAG on their surfaces. By immunodiffusion analysis, anti-HBe did not form precipitin bands with the purified forms of HBsAg and hyperimmune guinea pig antisera to these forms did not react with HBeAg. Lines of non-identity were observed between the HBeAg determinants (e1 and e2) and the Dane particles and filaments isolated from an HBeAg-positive serum. Finally, anti-HBe failed to precipitate the polymerase-positive subpopulation of Dane particles, indicating that anti-HBe has no direct role in virus neutralization.
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Isoelectric Points of Polypeptides of Standard Poliovirus Particles of Different Serological Types and of Empty Capsids and Dense Particles of Poliovirus Type 1
More LessSUMMARYThe isoelectric points of polypeptides of standard and dense poliovirus particles and of empty capsids have been determined by isoelectric focusing in urea and by two-dimensional analysis. Comparing virus strains belonging to the three serological types of poliovirus, differences in the pI of some, but not all of the structural polypeptides are found. The pI of polypeptides of dense particles and of empty capsids are identical with those of standard particles. Polypeptide VPo present in empty capsids has a pI between those of VP4 and VP2.
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Reversible Change in the Nucleoprotein Composition of Bromoviruses after Multiplication in Chenopodium hybridum L.
More LessSUMMARYBrome mosaic virus (BMV) and cowpea chlorotic mottle virus (CCMV), propagated in two varieties of Chenopodium hybridum L., showed a considerable change in the relative proportions of the RNA and nucleoprotein components, as compared to virus propagated in Hordeum vulgare and Vigna unguiculata respectively. The reversible change was independent of the type of infection in C. hybridum: local necrotic, local chlorotic or systemic.
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Volumes and issues
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Volume 105 (2024)
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Volume 104 (2023)
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Volume 103 (2022)
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Volume 102 (2021)
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Volume 101 (2020)
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Volume 100 (2019)
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Volume 99 (2018)
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Volume 98 (2017)
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Volume 97 (2016)
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Volume 96 (2015)
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Volume 95 (2014)
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Volume 94 (2013)
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Volume 93 (2012)
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Volume 92 (2011)
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Volume 91 (2010)
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Volume 90 (2009)
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Volume 89 (2008)
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Volume 88 (2007)
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Volume 87 (2006)
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Volume 86 (2005)
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Volume 85 (2004)
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Volume 84 (2003)
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Volume 83 (2002)
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Volume 82 (2001)
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Volume 81 (2000)
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Volume 80 (1999)
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Volume 79 (1998)
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Volume 78 (1997)
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Volume 77 (1996)
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Volume 76 (1995)
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Volume 75 (1994)
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Volume 74 (1993)
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Volume 73 (1992)
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Volume 72 (1991)
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Volume 71 (1990)
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Volume 70 (1989)
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Volume 69 (1988)
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Volume 68 (1987)
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Volume 67 (1986)
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Volume 66 (1985)
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Volume 65 (1984)
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Volume 64 (1983)
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Volume 63 (1982)
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Volume 62 (1982)
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Volume 61 (1982)
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Volume 60 (1982)
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Volume 59 (1982)
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Volume 58 (1982)
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Volume 57 (1981)
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Volume 56 (1981)
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Volume 55 (1981)
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Volume 54 (1981)
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Volume 53 (1981)
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Volume 52 (1981)
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Volume 51 (1980)
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Volume 50 (1980)
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Volume 49 (1980)
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Volume 48 (1980)
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Volume 47 (1980)
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Volume 46 (1980)
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Volume 45 (1979)
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Volume 44 (1979)
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Volume 43 (1979)
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Volume 42 (1979)
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Volume 41 (1978)
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Volume 40 (1978)
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Volume 39 (1978)
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Volume 38 (1978)
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Volume 37 (1977)
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Volume 36 (1977)
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Volume 35 (1977)
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Volume 34 (1977)
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Volume 33 (1976)
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Volume 32 (1976)
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Volume 31 (1976)
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Volume 30 (1976)
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Volume 29 (1975)
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Volume 28 (1975)
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Volume 27 (1975)
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Volume 26 (1975)
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Volume 25 (1974)
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Volume 24 (1974)
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Volume 23 (1974)
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Volume 22 (1974)
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Volume 21 (1973)
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Volume 20 (1973)
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Volume 19 (1973)
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Volume 18 (1973)
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Volume 17 (1972)
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Volume 16 (1972)
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Volume 15 (1972)
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Volume 14 (1972)
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Volume 13 (1971)
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Volume 12 (1971)
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Volume 11 (1971)
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Volume 10 (1971)
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Volume 9 (1970)
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Volume 8 (1970)
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Volume 7 (1970)
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Volume 6 (1970)
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Volume 5 (1969)
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Volume 4 (1969)
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Volume 3 (1968)
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Volume 2 (1968)
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Volume 1 (1967)