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Volume 50,
Issue 4,
2001
Volume 50, Issue 4, 2001
- Short Article
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Failure of Mycoplasma pneumoniae infection to confer protection against Mycoplasma genitalium: observations from a mouse model
More LessMycoplasma pneumoniae and M. genitalium are genomically distinct but share antigens that induce some serological cross-reactivity. Therefore, the possibility that M. pneumoniae infection of the human respiratory tract might provide immunity to M. genitalium infection of the genital tract was considered. Because of the difficulty of assessing this proposition in man, it was evaluated experimentally in a mouse model. Female BALB/c mice were susceptible to infection of the vagina with M. pneumoniae , whereas those infected previously in the oropharynx with M. pneumoniae were completely immune to infection of the vagina with this mycoplasma. However, all mice with such a respiratory tract infection were susceptible to infection of the vagina with M. genitalium . The findings suggest that an M. pneumoniae infection of the human respiratory tract is unlikely to influence infection of the genital tract by M. genitalium .
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Influence of infection of cells with bacteria associated with reactive arthritis on the peptide repertoire presented by HLA-B27
Reactive arthritis (ReA) after infections with various gram-negative bacteria is strongly associated with the MHC class I molecule HLA-B27. It is supposed that the B27 molecule itself plays a role in the pathogenesis of ReA by presenting antigenic peptides to cytotoxic T lymphocytes. The peptide repertoires presented by Salmonella - , Shigella - and non-infected cells were compared to identify such peptides. From the peptides isolated from the B27 molecules of these cells, profiles were generated by reversed-phase chromatography and peaks present in the profiles from infected cells but not in profiles from non-infected cells were studied for their peptide compositions. Some sequences with identity to those in human histone H3, human ribosomal protein S17 and the heavy chain of HLA-B27 itself were detected only in profiles from infected cells. All peptides identified from infected cells contained the B*2705 peptide-binding motif. The data suggest that HLA-B27-positive cells infected with ReA-inducing bacteria show an increased presentation of certain self-peptides. There was no evidence for altered peptide-binding specificity of B27 after infection. However, the interpretations were hampered by the variation in peptide presentation between different experiments.
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- Review Article
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Anti-cariogenic properties of tea (Camellia sinensis)
More LessVarious components in green and black tea, the beverages made by infusing appropriately processed dried leaves of Camellia sinensis , notably simple catechins, have properties in vitro that suggest an anti-cariogenic activity. These include: a direct bactericidal effect against Streptococcus mutans and S. sobrinus ; prevention of bacterial adherence to teeth; inhibition of glucosyl transferase, thus limiting the biosynthesis of sticky glucan; inhibition of human and bacterial amylases. Studies in animal models show that these in-vitro effects can translate into caries prevention. A limited number of clinical trials in man suggest that regular tea drinking may reduce the incidence and severity of caries. If substantiated, this could offer a very economical public health intervention.
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- Host Response To Infection
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Mucosal and systemic antibody responses to the lipopolysaccharide of Escherichia coli O157 in health and disease*
More LessMucosal immunity in the gastrointestinal (GI) tract is a primary defence against GI pathogens. We hypothesise that a mucosal response to lipopolysaccharide (LPS), especially to the common (core) determinants of GI pathogenic Escherichia coli strains, is protective. The aims of this study were to investigate the specificities, levels and development of humoral responses in health and GI disease to the R3 LPS core and O-polysaccharide of E. coli O157. The purpose was to try to predict whether vaccination or passive immunisation might induce protection. Wherever possible, paired whole gut lavage fluid (WGLF) and serum samples were collected for comparison of the mucosal and systemic responses. Matched saliva samples were also collected from some study groups. The patient groups included those with acute E. coli O157 disease (serum only), patients convalescing after E. coli O157 infections, and patients undergoing routine investigation for GI conditions but subsequently shown to be immunologically normal. Some samples of WGLF from patients with Crohn's disease (CRO) and ulcerative colitis (UC) were included to allow comparisons with patients with inflammatory conditions known to alter antibody secretion in the GI tract. The healthy groups from whom serum and saliva only were taken included blood donors, healthy volunteers and a group of slaughterhouse workers. This latter group was likely to have been exposed regularly to faecal bacteria from animals and antibody specificities might have been expected to be different from other healthy individuals. Levels and classes of antibodies were determined by ELISA with microtitration plates coated with polymyxin complexes of whole LPS extracted from E. coli O157 and LPS from the E. coli R3 rough mutant. Antibodies of IgG and IgM classes were measured in serum and IgA was measured in WGLF and saliva. IgG antibodies to the O157 LPS and the R3 core oligosaccharide were detected in the serum of healthy blood donors. Patients with acute E. coli O157 disease showed elevated levels of serum IgM to O157 LPS and R3, with IgG levels raised only to R3. In serum from convalescent patients, IgG to O157 LPS was significantly above the control groups only in the period 6–16 weeks after infection. Total IgA levels were similar in WGLF specimens from all groups, except the patients with UC, whose levels were much higher. Specific IgA levels were higher in the E. coli O157 convalescent group, but there were no significant correlations overall. UC patients had significantly lower levels of IgA to O157 and CRO patients had higher O157 IgA levels than UC patients and healthy volunteers. In serum, inhibition of ELISA showed that the response to the O157 LPS was due in part to a response to the R3 oligosaccharide component. This response was much more pronounced in the healthy and non-O157 groups than in convalescent patients. There was no correlation between specific IgA antibody levels in saliva and matched specimens of WGLF, and levels in sequential saliva specimens fluctuated widely. The significant IgG and IgA responses to the R3 core suggest that there is immunological memory to this oligosaccharide LPS component which may have a role in protection against E. coli LPS both systemically and locally in the GI tract. Boosting of this mucosal response to the LPS core, either naturally through exposure or by active or passive immunisation, may confer protection. Finally, antibody responses to E. coli O157 must be interpreted with caution, as the response detected is a sum of responses to the O-specific polysaccharide and the R3 core.
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- Bacterial Characterisation
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Demonstration of the Rb1 lipopolysaccharide core structure in Salmonella strains with the monoclonal antibody M105
More LessThe lipopolysaccharide (LPS) from 42 strains representing 19 Salmonella serogroups was differentiated into characteristic ladder-like profiles by SDS-PAGE analysis. The core-specific antibody M105 (Ra, Rb1 and Rb2) was used in an immunoblot assay of SDS-PAGE-separated LPS molecules. The M105 antibody bound to the R-type LPS of 18 of the 20 Salmonella strains tested. The results demonstrate that S. enterica serotype Godesberg, S. Adelaide (one of two strains), S. Milwaukee, S. Niarembe, S. Bere and S. Arizonae (serogroup 63) have an atypical LPS core structure which is Rb1 type.
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- Bacterial Pathogenicity
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Enhancement of the virulence of Aeromonas caviae diarrhoeal strains by serial passages in mice
Thirteen clinical Aeromonas caviae isolates from the faeces of 13 children with mild to severe diarrhoea were tested for enhancement of mouse lethality, adhesion ability, siderophore and cholera toxin cross-reactive (CTC) factor production, by four consecutive passages through mice by intraperitoneal injection of A. caviae suspensions. The passaged A. caviae strains were re-isolated from monomicrobic cardiac blood samples and inocula were prepared for the next passage. All A. caviae isolates possessed the ability to adhere to the mucosal epithelial surface of the rabbit small intestine. Serial passage in mice showed that the virulence of some isolates for mice was increased in terms of percentage mortality and a lowering of the LD50. For some of the isolates, but not all, serial passage appeared to increase siderophore production and adhesion to rabbit small intestinal cells. For the A. caviae isolates tested, increased values of the CTC factor were observed after passage. A clear correlation was observed between the lowering of LD50 and the enhancement of CTC factor production after passage in mice. These results indicate that the A. caviae isolates possessed virulence factors.
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Identification of a 43-kDa outer-membrane protein as an adhesin in Aeromonas caviae
Aeromonas spp. are associated with intestinal and extra-intestinal infections. However, the virulence factors of A. caviae remain, for the most part, poorly known. This study examined the interactions involved in the adherence of A. caviae isolates Ae56, Ae391 and Ae398 to HEp-2 cells. All strains expressed high levels of aggregative adherence. Maximum adhesion occurred with bacteria grown at 22°C, but transmission electron microscopy did not reveal the presence of fimbrial structures on the bacterial cell surface. Outer-membrane proteins (OMPs) extracted from isolate Ae398, grown at 22°C and 37°C, showed similar SDS-PAGE protein profiles. Most proteins were < 60 kDa. A major 43-kDa protein was seen only in the boiled OMP extract. The biotinylated 43-kDa protein bound specifically to HEp-2 cells. Microbeads coated with the 43-kDa protein were also adherent to HEp-2 cells, and anti-43-kDa protein antibody blocked adherence of 43-kDa protein-coated latex beads. These data suggest that the 43-kDa OMP functions as an adhesin in A. caviae .
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Involvement of the heparan sulphate-binding proteins of Helicobacter pylori in its adherence to HeLa S3 and Kato III cell lines
More LessTo determine whether Helicobacter pylori heparan sulphate-binding proteins (HSBPs) are involved in the adherence of H. pylori to HeLa and Kato III cells, monolayers were pre-incubated with various preparations and concentrations of H. pylori HSBPs at 37°C, washed and then challenged with bacteria. HSBPs did not prevent but enhanced H. pylori adherence. However, challenging cultured cells with H. pylori previously incubated with rabbit anti-HSBP IgG resulted in significant inhibition of bacterial adherence. These data demonstrate that the extracellular HSBP plays an important role in promoting H. pylori attachment to Kato III and HeLa S3 cells, that adhesion of H. pylori to Kato III and HeLa S3 cells is promoted by the presence of the 71.5-kDa extracellular HSBP and that rabbit polyclonal antibodies against this HSBP can inhibit adhesion of H. pylori to the cultured cell lines and detach cell-bound H. pylori .
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- Mycology
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Molecular epidemiology of airway colonisation by Aspergillus fumigatus in cystic fibrosis patients
A total of 109 sequential and multiple Aspergillus fumigatus isolates corresponding to 41 samples from seven cystic fibrosis (CF) patients was typed by random amplification of polymorphic DNA (RAPD) with the primer NS3 from the fungal ribosomal gene 18S subunit, and by sequence-specific DNA primer (SSDP) analysis. RAPD typing of the isolates revealed 10 different genotypes, whereas nine genotypes were identified by SSDP. Combination of the two typing methods permitted the differentiation of 25 overall genotypes. The colonisation typing patterns differed greatly between patients colonised for <1 year by A. fumigatus and long-term colonised patients. Two of three recently colonised patients presented a large number of types even in the same sample, unlike the chronically colonised patients, who harboured a limited number of genotypes. In the latter, the occurrence of a dominant genotype, usually the overall genotype 2, tended to reflect to the duration of colonisation. Moreover, anti-catalase antibodies to A. fumigatus appeared in most cases to be in response to genotype 2. These findings suggest that some strains of A. fumigatus may be selected during prolonged colonisation of the airways in CF patients.
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Susceptibility to fluconazole of Candida clinical isolates determined by FUN-1 staining with flow cytometry and epifluorescence microscopy
The susceptibility of clinical Candida isolates to fluconazole was assayed by flow cytometry (FCM) and epifluorescence microscopy (EFM), with FUN-1 staining. In all, 25 clinical isolates of Candida spp. (12 sensitive, 3 dose-dependently sensitive and 10 resistant to fluconazole according to the NCCLS M27-A protocol) were treated with increasing concentrations of fluconazole during 1 or 2 h staining with FUN-1 for 30 min and analysed, respectively, by FCM at 575 nm (FL2) and by EFM. Fluconazole-susceptible strains showed an increased accumulation of FUN-1 in comparison with controls as determined by FCM and a reduced metabolic processing of the probe, confirmed by EFM. Conversely, resistant strains showed decreased FUN-1 staining and were able to process the probe. The fluconazole minimal inhibitory concentrations (MICs) determined by FCM or EFM after FUN-1 staining compared very well with the corresponding values determined by the M27-A protocol, indicating that FUN-1 staining can be used as an alternative to the conventional method. MIC values of resistant strains, with the exception of C. krusei , were lower when treatment with fluconazole followed pre-incubation with 0.1 mm sodium azide, a concentration known to inhibit the activity of efflux pumps. These results show that FUN-1 staining can be used as an alternative and rapid method for the assessment of susceptibility of Candida clinical isolates to fluconazole. Furthermore, the results suggest that resistance of Candida cells to fluconazole, with the exception of C. krusei strains, is likely to be due to the activity of efflux pumps.
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- Paleomicrobiology
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Molecular analysis of skeletal tuberculosis in an ancient Egyptian population
More LessA paleomicrobiological study was performed on 37 skeletal tissue specimens from cadavers in the necropolis of Thebes-West, Upper Egypt, (2120–500 BC) and four from the necropolis of Abydos (3000 BC). The subjects had typical macromorphological evidence of osseous tuberculosis (n = 3), morphological alterations that were not specific, but probably resulted from tuberculosis (n = 17), or were without morphological osseous changes (n = 21). DNA was extracted from these bone samples and amplified by PCR with a primer pair that recognised the Mycobacterium tuberculosis complex insertion sequence IS 6110 . To confirm specificity of the analysis, the amplification products of several samples were subjected to restriction enzyme digestion, or direct sequencing, or both. In 30 of the 41 cases analysed, ancient DNA was demonstrated by amplification by the presence of the human β-actin or the amelogenin gene and nine of these cases were positive for M. tuberculosis DNA. The results were confirmed by restriction endonuclease digestion and sequencing. A positive result for M. tuberculosis DNA was seen in two of the three cases with typical morphological signs of tuberculosis and amplifiable DNA, in five of 13 non-specific, but probable cases (including two cases from c . 3000 BC), but also in two of 14 cases without pathological bone changes. These observations confirm that tuberculosis may be diagnosed unequivocally in skeletal material from ancient Egypt, even dating back to c . 3000 BC. As a positive molecular reaction was observed in most of the typical cases of skeletal tuberculosis, in about one-third of non-specific, but probable tuberculous osseous changes and, surprisingly, in about one-seventh of unremarkable samples, this suggests that infection with M. tuberculosis was relatively frequent in ancient Egypt.
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- Serological Diagnosis
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Cloning and characterisation of malE in Burkholderia pseudomallei
More LessNo recombinant protein is available for serodiagnosis or skin test in the diagnosis of melioidosis. This report describes the cloning of the malE gene, which encodes an immunogenic protein of Burkholderia pseudomallei . Bi-directional DNA sequencing of malE revealed that the gene contained a single open reading frame encoding 416 amino acid residues with a predicted molecular mass of 44.4 kDa. BLAST analysis showed that the putative protein encoded by malE is homologous to the maltose-binding protein (MBP) of other bacteria. It has 48% and 63% amino acid identity and similarity with the MBP of Brucella abortus , and malE complementation assay showed that it partially complemented the function of the MBP of Escherichia coli . Several highly conserved regions among the MBP of B. pseudomallei , Br. abortus , Salmonella enterica serotype Typhimurium, E. coli and Enterobacter aerogenes were observed. These regions represent signatures A, B, C, D and F identified in the MBP of E. coli . Further sequence analysis revealed that the first 24 amino acid residues of the MBP of B. pseudomallei probably represent the N-terminal signal peptide of the protein. Similar to the signal peptide of the MBP of E. coli , Ent. aerogenes and S . Typhimurium, the MBP of B. pseudomallei contains two basic residues in the first eight amino acids, followed by a hydrophobic core, with the last three amino acids in the signal peptide being Ala-Gln-Ala, conforming to the consensus sequence Ala-X-Ala at positions –3 to –1 relative to the site of proteolytic cleavage for recognition by signal peptidase I. Further studies on serodiagnosis of melioidosis with recombinant MBP should be performed.
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- Book Reviews
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Volumes and issues
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Volume 74 (2025)
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Volume 73 (2024)
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Volume 72 (2023 - 2024)
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Volume 71 (2022)
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Volume 70 (2021)
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Volume 69 (2020)
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Volume 68 (2019)
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Volume 67 (2018)
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Volume 66 (2017)
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Volume 65 (2016)
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Volume 64 (2015)
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Volume 63 (2014)
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Volume 62 (2013)
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Volume 61 (2012)
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Volume 60 (2011)
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Volume 59 (2010)
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Volume 58 (2009)
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Volume 57 (2008)
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Volume 56 (2007)
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Volume 55 (2006)
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Volume 54 (2005)
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Volume 53 (2004)
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Volume 52 (2003)
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Volume 51 (2002)
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Volume 50 (2001)
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Volume 49 (2000)
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Volume 48 (1999)
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Volume 47 (1998)
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Volume 46 (1997)
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Volume 45 (1996)
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Volume 44 (1996)
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Volume 43 (1995)
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Volume 42 (1995)
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Volume 41 (1994)
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Volume 40 (1994)
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Volume 39 (1993)
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Volume 38 (1993)
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Volume 37 (1992)
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Volume 36 (1992)
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Volume 35 (1991)
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Volume 34 (1991)
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Volume 33 (1990)
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Volume 32 (1990)
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Volume 31 (1990)
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Volume 30 (1989)
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Volume 29 (1989)
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Volume 28 (1989)
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Volume 27 (1988)
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Volume 26 (1988)
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Volume 25 (1988)
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Volume 24 (1987)
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Volume 23 (1987)
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Volume 22 (1986)
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Volume 21 (1986)
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Volume 20 (1985)
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Volume 19 (1985)
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Volume 18 (1984)
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Volume 17 (1984)
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Volume 16 (1983)
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Volume 15 (1982)
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Volume 14 (1981)
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Volume 13 (1980)
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Volume 12 (1979)
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Volume 11 (1978)
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Volume 10 (1977)
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Volume 9 (1976)
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Volume 8 (1975)
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Volume 7 (1974)
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Volume 6 (1973)
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Volume 5 (1972)
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Volume 4 (1971)
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Volume 3 (1970)
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Volume 2 (1969)
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Volume 1 (1968)
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