- Volume 47, Issue 7, 1998
Volume 47, Issue 7, 1998
- Editorial
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- Review Article
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Recent developments in bacterial conjugate vaccines
More LessStudy of the epidemiology of childhood infection reveals that the brunt of disease for a number of invasive bacterial infections is borne by children under the age of 4 years. Haemophilus influenzae type b (Hib), Neisseria meningitidis and Streptococcus pneumoniae, the three most important causes of childhood meningitis, illustrate this phenomenon, which is caused by the inability of infants and young children to mount antibodies to the carbohydrates that form a capsule surrounding these organisms. Carbohydrates are traditionally viewed as T-independent antigens with a number of unique and important immunological properties that are not encountered when inducing an immune response to proteins. These properties include no overt requirement for the presence of T cells to induce an immune response, dominance of IgM, failure to induce memory following immunisation, an absence of affinity maturation following immunisation, and poor immunogenicity in infants, the elderly and the immunocompromised. These properties of carbohydrates have precluded the use of pure carbohydrate vaccines in those patients most at risk. Conjugate vaccine technology, where a carbohydrate antigen is coupled chemically to a protein carrier, has overcome the limitations of carbohydrates as vaccine antigens by rendering the carbohydrate moiety of such vaccines immunogenic, even in the very young. The dramatic success of the Hib conjugate vaccines, the first conjugates licensed clinically for human use, in reducing the incidence of invasive Hib disease has demonstrated the potential value of such conjugate vaccines. Similar technology is, therefore, being applied to a number of other vaccines in development, including N. meningitidis (groups A and C) and S. pneumoniae vaccines. The large number of pneumococcal carbohydrate serotypes that require inclusion in a vaccine makes this conjugate formulation far more complicated than that for Hib, and it is likely that the dramatic success of the Hib conjugate vaccines will be more difficult to repeat for the pneumococcus.
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- Antimicrobial Susceptibility
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Natural antibiotic susceptibility of Providencia stuartii, P. rettgeri, P. alcalifaciens and P. rustigianii strains
More LessThe natural antibiotic susceptibility of 38 Providencia rettgeri, 35 P. stuartii, 23 P. alcalifaciens and 20 P. rustigianii strains was examined. MIC values were determined by a microdilution procedure and evaluated by a table calculation programme. P. stuartii was the least susceptible Providencia sp. and was naturally resistant to tetracyclines, some penicillins, older cephalosporins, sulphamethoxazole and fosfomycin and to antibiotics to which other species of Enterobacteriaceae are also resistant. It was naturally sensitive to modern penicillins and cephalosporins, carbapenems and aztreonam, but its susceptibility to aminoglycosides and quinolones was difficult to assess. P. alcalifaciens and P. rustigianii strains were the most susceptible Providencia spp. They were naturally sensitive or intermediate to tetracyclines and sensitive to aminoglycosides and quinolones. Susceptibility to sparfloxacin, biapenem and sulphamethoxazole permitted the discrimination of P. alcalifaciens and P. rustigianii strains. The natural antibiotic susceptibility of P. rettgeri strains was between that of P. stuartii and that of the other providenciae. P. rettgeri was resistant to tetracyclines and fosfomycin, but more susceptible to aminoglycosides, quinolones, fosfomycin and numerous β-lactam antibiotics than P stuartii. A database is described of the natural antibiotic susceptibilities of Providencia spp. It can be used for the validation of antibiotic susceptibility test results of these micro-organisms.
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- Clinical Microbiology
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Group B streptococcal bacteraemia in the elderly
More LessThe aim of this retrospective study was to determine the clinical spectrum of group B streptococcal (GBS) bacteraemia in patients over 70 years old. Sixty-six adults with GBS bacteraemia were reviewed over a 5-year period. Disease characteristics, clinical diagnoses and underlying disease were compared in 33 older patients (mean age 82.4 years) and 33 younger patients (mean age 54.2 years). The older patients were also compared with a control group (mean age 81.3 years). Urinary tract infection (39%), skin infection (33%) and pneumonia (24%) were the most frequent clinical diagnoses in older patients. Urinary tract infection (39% versus 6%) was significantly more frequent in older than in younger patients. One underlying disease and one condition were more frequent in elderly patients: congestive heart failure (39% versus 6%) and being bedridden (36% versus 0%). A comparison with the older control group showed that being bedridden was highly associated with GBS bacteraemia and was an important mortality factor amongst older patients (10% versus 30%). In conclusion, GBS disease in the elderly was found to be a severe clinical problem with a high mortality despite appropriate treatment.
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- Oral Microbiology
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Two different types of humoral immune response to Actinobacillus actinomycetemcomitans in high-responder periodontitis patients
More LessActinobacillus actinomycetemcomitans is considered to be an aetiological agent in various forms of periodontitis, with serotype b-specific carbohydrate being the immunodominant antigen of A. actinomycetemcomitans Y4 in high-responder patients. Lipopolysaccharide (LPS) of the organism may also be an important antigen. The purpose of the present study was to clarify the importance of LPS as an antigen of A. actinomycetemcomitans. Twenty patients who had high antibody titres to strain Y4 were selected, and the reactivity of their sera with LPS was determined by ELISA and Western blotting. Two groups of patients were observed: group 1 had high IgG titres only to serotype b strain, whereas group 2 had high IgG titres to serotypes a, b and c strains. The results of adsorption tests showed that anti-A. actinomycetemcomitans Y4 antibody in group 1 patients mostly consisted of antibody reactive with the serotype b-specific carbohydrate, whereas the antibody in group 2 patients mostly consisted of antibody reactive with the LPS of all serotypes. These data show that anti-LPS antibody is present and predominant in anti-A. actinomycetemcomitans Y4 antibody from some high-responder patients, and indicate an important role for LPS as an antigen in the humoral immune response to the organism.
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An association of membrane-damaging toxins from coagulase-negative staphylococci and chronic orofacial muscle pain
More LessForty-six patients presenting with chronic orofacial muscle pain and eight age- and sex-matched control subjects were investigated for the carriage prevalence of, and exotoxin production by, coagulase-negative staphylococci (CNS). The eight control subjects were selected from an initial group of 41 subjects on the basis of the absence of musculoskeletal symptoms. There was a significantly higher prevalence and multiple carriage of four or more strains of CNS in patients with chronic muscle pain than in control subjects (23 versus 9 isolates/10 subjects). Two of the 103 CNS isolates from patients with muscle pain and none from the control subjects produced toxic shock syndrome toxin 1 (TSST-1), suggesting that pyrogenic toxins do not significantly contribute to the aetiology of chronic muscle pain. There was a significantly higher prevalence of δ-haemolysin (41 of 114) and ‘horse’-haemolysin (56 of 114) production by CNS isolates from patients with chronic muscle pain compared with those from control subjects. None of the control subjects was colonised with CNS that produced significant amount of either δ- or ‘horse’-haemolysin, whereas 35 of 44 patients with chronic orofacial muscle pain were colonised with CNS that produced significant amounts of ‘horse’-haemolysin, 37 that produced δ-haemolysin and 33 that produced both δ- and horse-haemolysin. This study suggests that membrane-damaging toxins, like δ- and ‘horse’-haemolysin, may play a role in the aetiology of chronic orofacial muscle pain.
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Production and sensitivity of bacteriocin-like activity among Porphyromonas gingivalis, Prevotella intermedia and Pr. nigrescens strains isolated from periodontal sites
More LessThe production of and sensitivity to bacteriocin-like activity among 44 strains of black-pigmented anaerobes isolated from periodontal sites were evaluated by both an overlay and an agar diffusion method. The species studied were Porphyromonas gingivalis, Prevotella intermedia and the closely related species Pr. nigrescens. Pr. intermedia strains (90%) produced bacteriocin-like activity against Pr. nigrescens and all Pr. nigrescens were active against Pr. intermedia. Both species showed a high degree of activity against P. gingivalis, whereas only one P. gingivalis strain produced bacteriocin-like activity against either of the other two species. Both Pr. nigrescens and Pr. intermedia showed some activity (40% and 20%, respectively) against other strains of the same species. Such bacteriocin production might be expected to influence the distribution of these black-pigmented species in vivo. Of 224 periodontal sites sampled, only 2.6% yielded mixed cultures of black-pigmented species and of these only one strain, a P. gingivalis isolate, produced bacteriocin-like activity against any of the other strains isolated from these sites. These data support the concept that local production of bacteriocin-like activity in vivo may contribute to the selection of the black-pigmented bacterial profile in subgingival sites.
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- Models Of Infection
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Bacterial translocation, intestinal microflora and morphological changes of intestinal mucosa in experimental models of Clostridium difficile infection
More LessBacteraemia and subsequent sepsis is one possible complication of Clostridium difficile infection. The aim of this study was to examine a correlation between bacterial translocation with morphological changes of intestinal mucosa and shifts of intestinal microflora in experimental models of C. difficile infection. A mouse model was used to study post-antibiotic shifts and mild C. difficile infection, and hamsters were used to study fatal enterocolitis. The influence of pro- and pre-biotics (lactobacilli and xylitol) were also studied in the hamster model. The quantitative composition of luminal and mucosal microflora was evaluated in different intestinal loci, inflammatory changes of mucosa were estimated in histological sections and bacterial translocation was detected in samples from blood, liver, spleen and mesenteric lymph nodes. In cases of mild C. difficile infection, the extent of disturbance of intestinal microflora appeared to be a more important promoting factor in translocation than inflammatory activity in the mucosa. Translocation was frequent in fatal enterocolitis, with facultative species predominating in the intestinal mucosa and also C. difficile in some cases. The combination of lactobacilli and xylitol had some protective effect against C. difficile infection in these models.
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Factors influencing the induction of infertility in a mouse model of Chlamydia trachomatis ascending genital tract infection
More LessIn women, infections due to Chlamydia trachomatis frequently result in long-term sequelae including chronic abdominal pain, ectopic pregnancy and infertility. In an attempt to characterise the pathogenesis of the infection, female C3H (H-2k) mice were inoculated intravaginally with different doses of C. trachomatis and then mated with proven male breeder mice. The inoculated mice developed a broad spectrum of clinical manifestations ranging from infertility to asymptomatic shedding. The dose inducing infertility in 50% of the mice was c. 105 inclusion-forming units of C. trachomatis. In another group of mice sampled at intervals after intravaginal inoculation, C. trachomatis was recovered from the upper genital tract starting at 24 h after infection. A higher percentage of animals infected during the luteal phase of the oestrous cycle had positive cultures from the middle and upper genital tract than when mice were inoculated during the follicular phase. These results indicate that rapid therapeutic intervention is required to avoid the sequelae resulting from C. trachomatis genital infection, and suggest that hormonal factors play a role in the pathogenesis of the disease.
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- Correspondence
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- Molecular Diagnosis
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Development and evaluation of a PCR-based immunoassay for the rapid detection of methicillin-resistant Staphylococcus aureus
More LessA multiplex polymerase chain reaction (PCR), involving detection of the mecA and femB genes, was combined with a novel immunoassay system capable of detecting specific PCR products. The resulting PCR-immunoassay was evaluated in comparison with conventional microbiological techniques used in the routine diagnostic laboratory for the rapid identification of methicillin-resistant Staphylococcus aureus (MRSA), either in pure culture or in overnight broth cultures obtained following enrichment of patient screening swabs. Among the 480 purified isolates of staphylococci and 246 enrichment broths examined, only one ‘false-negative’ result was obtained by PCR, compared with 18 ‘false-negative’ results obtained by conventional methodology and demonstrated by further conventional examination. Five demonstrable ‘false-positive’ results were obtained by conventional methodology, compared with a possible 10 by the PCR-immunoassay, although it was not certain that these 10 PCR results were true ‘false positives’ as, by definition, MRSA could not be isolated by conventional methodology. The results indicated that the routine diagnostic laboratory was encountering difficulties in identifying MRSA correctly, and that the conventional microbiological techniques lacked sensitivity. Overall, the PCR technique was more accurate and sensitive than conventional methodology in detecting MRSA, and results were available within 24 h of screening swabs arriving in the laboratory, compared with a minimum of 48–72 h by conventional techniques. The immunoassay system added to the usefulness of the method by allowing the detection of specific PCR products within 5 min of completing the PCR, without the normal additional step of agarose gel electrophoresis.
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Comparison of two serological methods and a polymerase chain reaction-enzyme immunoassay for the diagnosis of acute respiratory infections with Chlamydia pneumoniae in adults
More LessChlamydia pneumoniae is a common respiratory tract pathogen. Serological methods currently used for the diagnosis of C. pneumoniae infection lack specificity, give ambiguous results from a single serum sample and often provide only a retrospective diagnosis. A prospective study was undertaken to assess whether PCR could be a useful addition to the serological techniques routinely practised for diagnosis. This study investigated 68 adult patients with a diagnosis of acute respiratory infection. Acute and convalescent serological determination of antibodies to C. pneumoniae were performed by means of an rELISA test and a micro-immunofluorescence (MIF) test. Nasopharyngeal aspirates or bronchoalveolar lavage specimens and bronchial aspirates obtained from the 68 patients were evaluated by PCR-enzyme immunoassay (PCR-EIA) for the presence of C. pneumoniae and by immunofluorescence assay and cell culture for virus identification. Mycoplasma pneumoniae serology was also performed. Eight patients (11.8%) were positive by either rELISA or PCR-EIA, or both, with an infection rate of 5 (18.5%) of 27 in patients with community-acquired pneumonia, 2 (9%) of 22 in asthmatic patients and 1 (5%) of 19 in patients with an exacerbation of chronic obstructive pulmonary disease. Serological evidence of acute infection was found in four of these patients with the rELISA test and in three others with the MIF test. PCR-EIA detected C. pneumoniae DNA in four specimens, but there were concordant results with both rELISA and PCR-EIA in only one patient. A positive PCR-EIA was also obtained in a patient who did not show an antibody response in acute serum. The discrepancy between serological and PCR-EIA results reflects the difficulties in routine laboratory diagnosis of C. pneumoniae infection and the necessity for further studies with optimised techniques.
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- Mycology
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An evaluation of the cost-effectiveness of using CHROMagar for yeast identification in a routine microbiology laboratory
More LessCHROMagar, a chromogenic differential culture medium, is claimed to facilitate the isolation and presumptive identification of certain clinically important yeast species, e.g., Candida albicans. This study evaluated the cost-effectiveness and time advantage of using it in comparison with Sabouraud dextrose agar (SDA). Three possible pathways, each of which included the use of one or both media, were compared in a routine laboratory. A total of 21 yeast isolates was cultured from 298 clinical samples from neutropenic and AIDS patients. An overall sensitivity of 95.2% was observed for each medium and primary isolation on CHROMagar was found to be 100% sensitive and 100% specific for C. albicans. For identification purposes, after initial culture the use of CHROMagar provided the most economical and least time-consuming method. Direct inoculation on to CHROMagar is recommended for blood cultures when yeast cells are seen on microscopy and where early appropriate therapy is imperative.
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- Virology
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Distribution of genotypes in the 5′ untranslated region of hepatitis C virus in Korea
More LessHepatitis C virus (HCV) is an important human pathogen that can cause acute and chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Recently, partial and entire sequence data from HCV isolates have been reported, suggesting various genotypes of HCV. The genotype may be correlated with the progression of hepatitis and maybe a prognostic marker of treatment. Thus, the availability of an assay for typing HCV RNA is important. This study developed a convenient method for genotyping HCV into six groups by PCR-RFLP with four restriction endonucleases (BstUI, HaeIII, NciI, RsaI) in the 5′ untranslated region (UTR) of HCV. The HCV genotypes from 169 patients with HCV infections in Korea were analysed. Two genotypes, type 1b and type 2a, accounted for 47.3% and 42.6% of HCV infections, respectively.
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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)