- Volume 50, Issue 11, 2001
Volume 50, Issue 11, 2001
- Editorial
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- Review Article
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The ecology of Staphylococcus species in the oral cavity
More LessWhilst the diversity of organisms present in the oral cavity is well accepted, there remains considerable controversy as to whether Staphylococcus spp. play a role in the ecology of the normal oral flora. Surprisingly little detailed work has been performed on the quantitative and qualitative aspects of colonisation or infection either by coagulase-negative staphylococci (CNS) or S. aureus. The latter is especially interesting in the light of present difficulties in eradicating carriage of methicillin-resistant S. aureus (MRSA) from the oropharynx in affected individuals. This paper reviews the current knowledge of staphylococcal colonisation and infection of the oral cavity in health and disease. S. aureus has been isolated from a wide range of infective oral conditions, such as angular cheilitis and parotitis. More recently, a clinical condition classified as staphylococcal mucositis has emerged as a clinical problem in many debilitated elderly patients and those with oral Crohn's disease. Higher carriage rates of both CNS or S. aureus, or both, in patients prone to joint infections raises the interesting possibility of the oral cavity serving as a potential source for bacteraemic spread to compromised joint spaces. In conclusion, there is a surprising paucity of knowledge regarding the role of oral staphylococci in both health and disease. Further work in this area may lead to benefits, such as improved decolonisation regimens for eradication of MRSA and acknowledgement of the mouth as a source of bacteraemic staphylococci.
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- Host Response To Infection
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Antigenic characterisation of a novel Streptococcus anginosus antigen that induces nitric oxide synthesis by murine peritoneal exudate cells
More LessA novel antigen that induces nitric oxide (NO) synthesis by murine peritoneal exudate cells (PEC) was prepared from a culture supernate of Streptococcus anginosus NCTC 10713 in dialysed medium by column chromatography with DEAE-Sephacel followed by size-exclusion high performance liquid chromatography (HPLC). A chemical analysis of the S. anginosus antigen (SAA) revealed that it mainly consisted of carbohydrates (rhamnose, N-acetylglucosamine, glucose and galactose), smaller quantities of protein and a trace amount of phosphorus. The SAA stimulated PEC from C57BL/6N mice to produce NO and accumulate induced NO synthetase (iNOS) mRNA in a dose-dependent manner, reaching a plateau with 10–30 μg/ml. Furthermore, a reverse transcription-PCR assay revealed that SAA 10 μg/ml could induce mRNA accumulation of tumour necrosis factor-α, interleukin (IL)-1β and IL-6 as well as iNOS. In contrast, Rantz-Randall antigen (RRA), a carbohydrate antigen prepared from the organisms, could not induce NO synthesis or cause the accumulation of iNOS mRNA, although cytokine production was observed after stimulation. The SAA-induced NO synthesis, but not the cytokine production, was sensitive to heat. Furthermore, an immunoblot analysis of SAA indicated that the 43-kDa protein band reacted with anti-SAA but not anti-RRA antibodies. In immunodiffusion, SAA reacted with both anti-SAA and anti-RRA antibodies, and the precipitin bands formed crossing lines, suggesting that SAA could possess two different antigenic components – one that reacts specificially with anti-SAA antibodies and another that has an identity similar to that of RRA. Taken together, SAA, a novel antigen of S. anginosus, was found to induce NO synthesis as well as produce inflammatory cytokines in murine PEC. It is suggested that the protein molecule of SAA may exclusively induce NO synthesis, and its carbohydrate component(s) could have a relationship to cytokine production.
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Protection against pulmonary infection with Klebsiella pneumoniae in mice by interferon-γ through activation of phagocytic cells and stimulation of production of other cytokines
The study was designed to determine the role of interferon (IFN)-γ in inflammatory responses against experimentally induced pneumonia caused by Klebsiella pneumoniae. The host immunological responses in IFN-γ gene knockout (IFN-γ−/−) mice and immunocompetent control mice were compared. K. pneumoniae strain T-113 was inoculated intranasally into anaesthetised mice to induce pneumonia. Infected control mice survived significantly longer than infected IFN-γ−/− mice. Viable bacterial counts in lungs and blood abruptly increased in IFN-γ−/− mice; in contrast, a gradual decrease in the number of bacteria was noted in control mice. During the early stages of infection, the concentrations of interleukin (IL)-1β and IL-6 in broncho-alveolar lavage fluid and IL-1β in serum of IFN-γ−/− mice were significantly lower than in control mice. During the late stage of infection, serum IL-6 level in IFN-γ−/− mice was significantly higher than in control mice. These results suggest that the defective immunological host response, including inflammatory cytokine production caused by deficiency of IFN-γ, is one of the mechanisms that allow the progression of pulmonary infection to systemic septicaemia.
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Promotion of platelet aggregation by sera from brucellosis patients with antiphosphatidylcholine antibodies
More LessResults obtained in this study suggest that in human brucellosis there is an antibody response against platelet-activating factor (PAF) and phosphatidylcholine (PC). The specificity of the antiphospholipid response was determined by inhibition assays. The PAF molecule was able to inhibit the anti-PC activity of the brucellosis-control serum. This inhibition capacity of PAF was similar to that of the phosphorylcholine (PYC) group. These results suggest that the inhibition activity could be attributed to the PYC group present in both PAF and PC molecules. Consequently, these findings support an immunodominant role of PYC in the antiphospholipid response of brucellosis. Furthermore, sera from patients infected with Brucella organisms were able to cause platelet aggregation, as were brucella phospholipids, suggesting a possible role of the antiphospholipid antibodies and phospholipids in the inflammatory response in brucellosis.
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- Diagnostic Microbiology
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International external quality assessment scheme for the laboratory diagnosis of diphtheria
An international external quality assessment (EQA) scheme has been established so as to evaluate the proficiency of specialist, national diphtheria reference laboratories in the laboratory diagnosis of diphtheria. Six simulated clinical specimens were freeze-dried and distributed to 23 participants in 20 countries. Participants were asked to isolate, identify and perform toxigenicity testing on any corynebacteria present and to complete a simple questionnaire describing the procedures and reagents used. Only three laboratories obtained correct biochemical and toxigenicity results for all six specimens. The majority of laboratories performed better with toxigenicity testing than with the biochemical identification. Of concern were the results from three laboratories that failed to isolate any corynebacteria from four or more of the specimens. In one centre this was shown to be due to lack of availability of ‘in-date’ media and, in the other two, was presumed to be due to lack of experience in primary laboratory diagnostics for this organism. It is essential that countries, globally, maintain awareness and laboratory capabilities in this specialised area of microbiology. EQA is an invaluable process, which enables laboratories to monitor, evaluate and improve their own performance in such areas.
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- Antimicrobial Resistance
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Susceptibility patterns of enteroaggregative Escherichia coli associated with traveller's diarrhoea: emergence of quinolone resistance
Enteroaggregative Escherichia coli (EAggEC) isolates were identified as a cause of traveller's diarrhoea in 50 (9%) of 517 patients and their antimicrobial susceptibility was determined. Molecular epidemiological characterisation and investigation of the mechanisms of acquisition of quinolone resistance among nalidixic acid-resistant EAggEC strains was performed. Seventeen (34%) of 50 patients needed antimicrobial therapy, because of persistence of symptoms in nine cases and the severity of symptoms in eight cases. Ampicillin and tetracycline resistance was high, whereas chloramphenicol and co-trimoxazole showed moderate activity and amoxicillin plus clavulanic acid, nalidixic acid and ciprofloxacin showed very good activity. Resistance to nalidixic acid was demonstrated in three isolates, two from patients who had travelled to India. In all three strains the resistance was linked to mutations in the gyrA gene alone or in both gyrA and parC genes. Although ciprofloxacin shows excellent in-vitro activity and could be useful in the treatment of traveller's diarrhoea in patients travelling abroad, it may not be useful in patients who have journeyed to India or to Mexico.
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Antibiotic resistance patterns of enterococci isolated from coastal bathing waters
More LessRecreational water should be considered a risk for enterococcal infections in regions with high utilisation and long exposure periods. A total of 1113 enterococcal isolates was obtained from 1670 bathing water samples from 120 bathing areas of seven prefectures in northern Greece. Enterococcus avium, E. raffinosus and E. faecium were the most prevalent species. Single, double and multiple antibiotic resistance patterns were observed in 33.5% 31.0% and 22.8% of the isolates, respectively. Resistance to erythromycin occurred most frequently, in 57.3% isolates, many of which also exhibited resistance to ciprofloxacin and rifampicin as well as high-level resistance to kanamycin and streptomycin. The results suggest that bathing water may contribute to the dissemination of uncommon enterococcal species that exhibit resistance to several antibiotics which are used to treat community-acquired infections.
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- Oral Microbiology
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Characterisation of Eubacterium-like strains isolated from oral infections
The genus Eubacterium currently includes a heterogeneous group of gram-positive, non-spore-forming anaerobic bacilli, many of which are slow growing, fastidious and generally unreactive in biochemical tests. As a consequence, cultivation and identification of isolates are difficult and the taxonomy of the group remains indifferent. In this study, 105 isolates from odontogenic infections, infections associated with dental implants or saliva from healthy subjects and provisionally assigned to the genus Eubacterium were subjected to phenotypic and genotypic analysis. Ninety-one of the isolates were identified as belonging to one of 14 previously described species: Atopobium parvulum (5 isolates), A. rimae (29), Bulleidia extructa (2), Cryptobacterium curtum (1), Dialister pneumosintes (1), Eubacterium saburreum (2), E. sulci (8), E. yurii subsp. yurii (1), Filifactor alocis (3), Lactobacillus uli (1), Mogibacterium timidum (13), M. vescum (6), Pseudoramibacter alactolyticus (6) and Slackia exigua (13). The remaining 14 isolates did not correspond to existing species. This study confirms the diversity of organisms provisionally assigned to the genus Eubacterium by conventional identification methods. This group of organisms is frequently isolated from oral infections but their role in the aetiology of these conditions has yet to be determined.
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- Microbial Pathogenicity
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New genes involved in Yersinia pestis fraction I biosynthesis
More LessAntigenic and immunochemical properties of Yersinia pestis fraction I (FI) preparations extracted by different methods were studied with polyclonal and monoclonal antibodies. The existence of mature FI in a form of a complex antigen whose subunits have different genetic control was demonstrated. Galactolipid was shown, with caf1 product, to be the second species-specific component of the FI complex molecule and is probably encoded by chromosomal genes. It, like caf1 product, was expressed in higher quantities at 37°C than at 28°C. Among FI subunits there were at least two proteins of 28 ± 2 kDa and 43 ± 2 kDa which were not specific for Y. pestis but were found also in all Yersinia spp. and some other bacteria. These proteins were synthesised independently of the incubation temperature (4°–40°C) and are possibly encoded chromosomally but outside the caf operon and galactolipid-encoding genes. Both proteins together with galactolipid comprise an envelope antigen found in pFra− or plasmidless Y. pestis strains. Organisation of Y. pestis FI (mature capsular antigen) in the form of a complex of the envelope antigen and the caf1 product is discussed.
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Expression of acid-stable proteins and modified lipopolysaccharide of Yersinia pestis in acidic growth medium
More LessGrowth medium simulating the phagolysosomal environment in which Yersinia pestis resides during its intracellular growth in vivo was made by acidification of Ca2+-deficient medium. When used for cultivation of Y. pestis EV-76 (pLCR+; pPst+;pFra+) and its isogenic derivatives – KM-217 (pLCR+;pPst−;pFra−) and KM-218 (pLCR−;Ppst−; pFra−) – this medium permitted survival and proliferation of viable bacteria without any growth restriction. Moreover, a correlation between the pH of growth medium and bacterial yield was established. Acidification completely inhibited fibrinolytic (pla protease) activity (PAA) of Y. pestis carrying pPst and allowed synthesis of specific outer-membrane proteins (Yops) without any degradation by the pla protease. Comparison of whole-cell lysates of the strains tested in PAAG-SDS showed that, in addition to previously described Yops, Y. pestis synthesised new acidic proteins which appeared only under acidic conditions and were encoded by pLCR or chromosomally. Some changes in O-specific polysaccharide chains of Y. pestis LPS that were dependent on cultivation temperature and pH of the medium were also demonstrated.
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- Molecular Epidemiology
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Interpreting the rising incidence of meningococcal disease in Belgium: the contribution of molecular typing
More LessDuring a period of increasing meningococcal disease incidence in Belgium, all 538 serogroup B and all 87 serogroup C strains isolated between 1996 and 1998 were investigated by PCR with the arbitrary primer D8635, which is able to identify lineage III strains. In all, 399 strains (64%) were attributed to lineage III on the basis of PCR-based typing. Since their introduction in the Belgian population in the early 1990s, lineage III strains have become increasingly variable in phenotype. Currently, they are represented by strains belonging to 38 different phenotypes, of which 25 were not found in the period 1990–1995. The 87 serogroup C strains were further investigated by pulsed-field gel electrophoresis (PFGE), and a subset of 30 strains was also investigated by multilocus sequence typing (MLST). Strains of phenotype C:2b:P1.5,2, which currently constitute the majority of the serogroup C strains, were demonstrated to belong to cluster A4. Comparison of the discriminatory ability of D8635-primed PCR, PFGE and MLST revealed that D8635-primed PCR was the least discriminatory method and PFGE the most discriminatory method. However, the MLST data were more readily interpreted than the PFGE fingerprint patterns and can be compared easily with data obtained in other studies. In conclusion, the ongoing increase of meningococcal disease in Belgium could be attributed not only to the further expansion of lineage III, but also to the introduction of C:2b:P1.5,2 strains of cluster A4 in to the Belgian population.
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A comparison of multilocus sequence typing and fluorescent fragment-length polymorphism analysis genotyping of clone complex and other strains of Neisseria meningitidis
J.V. HOOKEY and C. ARNOLDFive National Collection of Type Culture (NCTC) strains and 14 isolates of Neisseria meningitidis , representing 13 outbreak isolates from within the UK, were examined by multilocus sequence typing (MLST) for seven house-keeping genes. The results were compared with those of fluorescent amplified fragment-length polymorphism (FAFLP) analysis. Phylogenetic inferences were made from 3284-nucleotide lengths of sequence for the 19 isolates, by distance and parsimony methods. Two clusters of isolates were delineated. The larger, comprising eight isolates – S1, S3, Ironville, P9, ET-37 (M99-241951), P7, P10 and P60 – shared 100–99.2% similarity and varied in only 40 nucleotides (∼1.22% variation) from the consensus sequence alignment. This cluster could be equated to the ET-37 complex because it had allelic signatures identical to MLST sequence types 11 and 50. These eight isolates were also assigned to one group by FAFLP. The reference ET-5 complex isolate ‘ET-5 (NG144/82)’ and an isolate (X9) from an outbreak in the north of England were also grouped together by MLST. They shared 99.2% similarity and differed within the aro E and fum C genes by 4 and 17 nucleotides, respectively. Their MLST sequence types were 32 and 661 and, therefore, these two isolates could be equated to the ET-5 complex. They also grouped together by FAFLP. A comparison of the resources required to apply MLST to the 19 isolates examined with those needed to characterise them by FAFLP indicated that FAFLP (a fragment-based genotyping method) is more cost-effective than the partial sequencing approach, MLST.
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- Authors' Correction
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Volumes and issues
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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)