- Volume 51, Issue 9, 2002
Volume 51, Issue 9, 2002
- Review Article
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Impact of meningococcal C conjugate vaccine in the UK
More LessThis review details the impact of the introduction of meningococcal serogroup C conjugate (MCC) vaccines in the UK. An overall reduction of 86.7% in the incidence of serogroup C infection in the targeted age groups has been observed from 1999 to 2001, with a concomitant decrease in deaths, from 67 in 1999 to 5 in 2001. The enhanced surveillance programme initiated to complement the introduction of MCC vaccines has been essential in generating data relating to vaccine coverage, vaccine failures and efficacy estimates. Vaccine coverage has exceeded 80% in all age groups targeted and up to the end of 2001, 25 confirmed and 1 probable vaccine failure have been observed in England and Wales. Efficacy estimates for England up to September 2001 were 91.5% in infants receiving three doses of MCC vaccine and 89.3% in toddlers receiving one dose of MCC vaccine (England). There is some evidence of herd immunity in unvaccinated cohorts of the target age groups, ranging from a reduction in disease incidence of 34% in 9–14 year olds to 61% in 15–17 year olds. Surveillance of the genotypic and phenotypic characteristics of invasive and carriage isolates has shown no evidence to date of capsular switching from serogroup C to serogroup B.
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- Diagnostic Methods
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Recombinant OspC from Borrelia burgdorferi sensu stricto, B. afzelii and B. garinii in the serodiagnosis of Lyme borreliosis
More LessGenes for the outer-surface protein C (OspC) from three north European human isolates of Borrelia burgdorferi sensu stricto, B. afzelii and B. garinii were cloned and sequenced. Polyhistidine-tagged recombinant OspC (rOspC) proteins were produced in Escherichia coli and used, after biotinylation, as antigens on streptavidin-coated plates in enzyme-linked immunosorbent assays (ELISA). In IgM ELISA, 30% (5/17) and 35% (6/17) of patients with erythema migrans (EM) in the acute or convalescent phase, respectively, reacted with one to three rOspCs. Of the patients, 53% (8/15) with neuroborreliosis (NB) and 53% (8/15) with Lyme arthritis (LA) had IgM antibodies to OspC. The immunoreactivity was stronger against rOspC from B. afzelii and B. garinii than against rOspC from B. burgdorferi sensu stricto. In early Lyme borreliosis (LB), rOspC and flagella performed equally well in detecting IgM antibodies. Cross-reactive antibodies to rOspC were observed in serum samples from patients with rheumatoid factor positivity and with syphilis or Epstein–Barr virus (EBV) infection. In IgM ELISA, thiocyanate in the serum dilution buffer reduced EBV-associated non-specific positive reactions. Of the patient sera examined in IgG ELISA, 30% (5/17) with EM in the acute phase, 35% (6/17) with EM in the convalescent phase, 33% (5/15) with NB and 60% (9/15) with LA were positive. Because of the heterogeneity of OspC, a polyvalent antigen with several OspC variants from at least B. afzelii and B. garinii is needed to improve the sensitivity of OspC ELISA in the serodiagnosis of LB in Europe.
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Thermo-tolerant Campylobacter fetus bacteraemia identified by 16S ribosomal RNA gene sequencing: an emerging pathogen in immunocompromised patients
Eight Campylobacter isolates that were able to grow at 25°C and 42°C and had the same biochemical profile were isolated from the blood of eight immunocompromised patients. Conventional biochemical tests were unable to determine whether they were isolates of thermo-tolerant C. fetus, H2S-negative C. hyointestinalis, or a new Campylobacter species. Sequencing of the 16S ribosomal RNA genes showed that all eight isolates had the same nucleotide sequence and this was identical to that of C. fetus (GenBank accession no. AF219233). All eight patients had underlying disease and two died despite antibiotic treatment. Because of the ability of C. fetus to grow over a wide range of temperatures and a higher incidence of bacteraemia by this organism than C. jejuni in the past 5 years in Hong Kong, thermo-tolerant C. fetus may be an emerging pathogen in immunocompromised patients in the years to come.
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- Antimicrobial Resistance
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Prevalence of resistant Helicobacter pylori isolates in Bulgarian children
The aim of this study was to assess the primary and combined resistances of Helicobacter pylori isolates obtained from paediatric patients in 2000–2001 to seven antimicrobial agents. Resistance rates of pre-treatment isolates from 115 children were investigated by the limited agar dilution method alone and by the E-test. The cut-off concentrations for resistance were: metronidazole >8 mg/L, clarithromycin and azithromycin >1 mg/L, clindamycin >4 mg/L, amoxicillin >0.5 mg/L, tetracycline >4 mg/L and ciprofloxacin >1 mg/L. Primary resistance rates were: metronidazole 15.8%, clarithromycin 12.4%, azithromycin 14.6%, clindamycin 20.0%, amoxicillin 0%, metronidazole + clarithromycin 4.5%, ciprofloxacin 6.0%, metronidazole + clarithromycin + ciprofloxacin 1.2%, tetracycline 3.1% and metronidazole + ciprofloxacin 1.2%. There were no significant age (1–9 years versus 10–18 years) or gender differences. Prevalence of both macrolide-resistant and intermediately susceptible strains was 21.9% for azithromycin and 15.9% for clarithromycin. Of 18 metronidazole-resistant isolates, 77.8% exhibited a metronidazole MIC ≥32 mg/L. H. pylori resistance rates to metronidazole, clarithromycin and both agents were relatively low in Bulgarian children. However, resistance was found to all drugs tested except for amoxicillin. The consumption of newer macrolides and tetracyclines could be related to the prevalence of resistance to the corresponding agents. There were no significant differences in primary resistance rates of H. pylori to antimicrobial agents between children and adults except for metronidazole. Multi-drug resistance to newer macrolides, metronidazole and ciprofloxacin in association with a slightly elevated amoxicillin MIC (0.38 mg/L) was detected in one strain.
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- Oral Microbiology
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Establishment of streptococci in the upper respiratory tract: longitudinal changes in the mouth and nasopharynx up to 2 years of age
More LessAs part of a series of longitudinal studies on the development of the indigenous microflora of the upper respiratory tract, the establishment of streptococci in the oral cavity and nasopharynx and IgA1 protease production by the early streptococcal flora was examined in 50 healthy Caucasian infants at the ages of 2, 6, 12, 18 and 24 months. In the oral cavity, streptococci were found in all infants on every sampling occasion, Streptococcus mitis biovar 1 being the main finding in each age group. S. salivarius and S. mitis biovar 2 reached their highest prevalence during the first year of life, whereas the prevalence of S. oralis and S. sanguis showed no significant increase before 12 months of age. Salivary streptococci mainly consisted of the above-mentioned species during the follow-up period. In contrast to the oral cavity, no stable colonisation pattern was observed for viridans streptococci in the nasopharynx. S. mitis biovar 1 and S. pneumoniae, a traditional respiratory pathogen, were the principal streptococcal species among nasopharyngeal isolates. IgA1 protease production by early streptococci was common in infancy. Among the oral streptococcal microflora, S. mitis biovar 1 (especially during the first year of life) and S. oralis and S. sanguis constituted the main species responsible for this enzyme activity. In the nasopharynx, IgA1 protease was produced by S. mitis biovar 1, S. oralis and S. pneumoniae. In conclusion, streptococcal colonisation differs in these two close habitats in the upper respiratory tract.
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- Correspondence
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- Microbial Pathogenicity
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Role of agr (RNAIII) in Staphylococcus aureus adherence to fibrinogen, fibronectin, platelets and endothelial cells under static and flow conditions
In the present study, the adherence of Staphylococcus aureus (strain 8325-4) and its RNAIII mutant (WA400) to immobilised fibrinogen and fibronectin, and to human endothelial cells (EC), was studied. [3H]Thymidine-labelled bacteria in stationary phase were incubated on the test surfaces for 20 min under static or flow (200/s) conditions. The results showed: (a) increased adherence of the RNAIII mutant to fibrinogen under static conditions, and decreased adherence of the mutant to fibronectin and EC under both static and flow conditions compared with the parental strain; (b) stronger ability of the mutant compared with the parental strain to induce platelet aggregation in suspension; (c) greater adherence of the parental strain and the mutant to EC pre-treated with platelet-rich plasma compared with platelet-poor plasma, and to EC pre-treated with platelet-poor plasma compared with control; (d) increased adherence of S. aureus to EC pre-treated with PMA-activated platelets and decreased adherence to EC pre-treated with tirofiban, a platelet glycoprotein IIb-IIIa inhibitor, which paralleled with increased adherence of PMA-activated platelets and decreased adherence of glycoprotein IIb-IIIa-blocked platelets to EC in the absence of bacteria; and (e) adherence of the mutant was more sensitive to pre-treatment of EC with plasma and PMA-activated platelets. In conclusion, RNAIII down-regulates S. aureus adherence to fibrinogen under static condition and up-regulates S. aureus adherence to fibronectin and EC under both static and flow conditions. The potentiating role of activated platelets in the presence of plasma in S. aureus adherence to EC is down-regulated by RNAIII, probably due to down-regulation of adherence to fibrinogen, the important plasma protein bridging S. aureus, platelets and EC.
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Production of attaching-effacing lesions in ligated large intestine loops of 6-month-old sheep by Escherichia coli O157:H7
Shiga-toxigenic Escherichia coli O157:H7 (STEC O157:H7) is associated with potentially fatal human disease, and a persistent reservoir of the organism is present in some farm animal species, especially cattle and sheep. The mechanisms of persistent colonisation of the ruminant intestine by STEC O157:H7 are poorly understood but may be associated with intimate adherence to eukaryotic cells. Intimate adherence, as evidenced by induction of attaching-effacing (AE) lesions by STEC O157, has been observed in 6-day-old conventional lambs after deliberate oral infection but not in older animals. Thus, the present study used a ligated intestinal loop technique to investigate whether STEC O157:H7 and other attaching-effacing E. coli may adhere intimately to the sheep large intestinal mucosa. To do this, four STEC O157:H7 strains, one STEC O26:K60:H11 and one Shiga toxin-negative E. coli O157:H7 strain, suspended in either phosphate-buffered saline or Dulbecco's modified Eagle's medium, were inoculated into ligated spiral colon loops of each of two lambs. The loops were removed 6 h after inoculation, fixed and examined by light and electron microscopy. AE lesions on the intestinal mucosa were produced by all the inoculated strains. However, the lesions were sparse and small, typically comprising bacterial cells intimately adhered to a single enterocyte, or a few adjacent enterocytes. There was little correlation between the extent of intimate adherence in this model and the bacterial cell density, pre-inoculation growth conditions of the bacteria or the strain tested.
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Detection of Helicobacter pylori DNA in the oral cavity and gastroduodenal system of a Venezuelan population
Dental plaque has been suggested as a reservoir for Helicobacter pylori but the hypothesis that the oral microflora may be a permanent reservoir of H. pylori is still controversial. The aims of this study were to determine the presence of H. pylori DNA in the gastric antrum and dental plaque of a Venezuelan population by PCR and to investigate the relationship between this infection and the oral hygiene index. Thirty-two patients from the Hospital Universitario de Caracas, attending for routine gastroscopy, and 20 asymptomatic subjects (control group) were evaluated. The patients’ gingiva and plaque were assessed by the gingival and plaque indices of Sillness and Löe. Supragingival plaque was analysed by a PCR for a specific internal urease gene. Gastric antrum biopsies were taken for histological examination and PCR. H. pylori was detected in antral samples from 24 (75%) of 32 patients, all of whom had chronic gastritis. H. pylori was also detected in dental plaque samples of 12 (37.5%) of the 32 patients. In 7 (58%) of these 12 patients, H. pylori was identified in the gastric biopsy. Seven patients with chronic gastritis carried H. pylori in dental plaque and antral samples. Of these patients, four also had dysplasia and one had metaplasia. Three subjects in the control group were positive by PCR. In the present study there was no correlation between H. pylori infection and dental hygiene, dental caries, periodontal disease or use of dentures. The oral cavity may be a reservoir for H. pylori infection and oral secretions may be an important means of transmission of this micro-organism. H. pylori in dental plaque may represent a risk factor for gastrointestinal re-infection and ulcer relapse after antibiotic therapy.
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Increased in-vitro and in-vivo biological activity of lipopolysaccharide extracted from clinical low virulence vacA genotype Helicobacter pylori strains
More LessHelicobacter pylori infection in man is associated with chronic gastritis and peptic ulcer disease. The virulence factors of the species are still under investigation. Among these, the lipopolysaccharide (LPS) is a potential pathogenic factor of the micro-organism, whose biological activity can be estimated by immunological parameters. The aim of this study was to determine the ability of pure LPS extracted from clinical isolates of H. pylori to induce mitogenicity, secretion of tumour necrosis factor-alpha (TNF-α), and spleen growth in a murine model. Rough and smooth LPS from Salmonella typhimurium were used as controls. The results showed that, like the control LPS, all extracts of LPS induced mitogenic activity, stimulated synthesis of TNF-α and induced spleen growth, although the effects produced by the majority of the H. pylori LPS samples analysed were less intensive than those produced by the S. typhimurium LPS. The immunological parameters analysed allowed the detection of two types of H. pylori LPS: one of low biological activity and one of high biological activity. The most active LPS was extracted from strains isolated from patients with increased mucous damage associated with epithelial regeneration. Surprisingly, these strains were cagA negative and belonged to a low virulence genotype according to vacA gene (s1bm2 and s2m2). The results suggest the need to re-evaluate the role of the LPS as a virulence factor for some strains of H. pylori.
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The effect of colonisation by Helicobacter pylori in Praomys (Mastomys) natalensis on the incidence of carcinoids
More LessAn animal model of experimental gastric Helicobacter pylori infection has been developed in the Z strain of Praomys (Mastomys) natalensis; this animal has been reported to develop gastric carcinoids and adenocarcinoma spontaneously. In the present study, male and female Mastomys were killed at 1, 2, 4, 8 and 16 weeks after H. pylori inoculation. Colonisation of H. pylori was maintained in the stomachs of all animals for up to 16 weeks. H. pylori were mainly found in the antrum. Lymphoid infiltration appeared in the antral lamina propria and submucosa in all male and female animals from 4 to 16 weeks after inoculation. On microscopic examination after immunostaining for H. pylori, the organisms were detected in the antral mucus layer of the gastric epithelium. Serum immunoglobulin G specific for H. pylori could be detected 2 weeks after inoculation in female and 4 weeks after inoculation in male Mastomys, and persisted throughout the 16-week study period. At 18 months after inoculation, H. pylori positive rates for male and female Mastomys were 15 of 21 and 7 of 27, respectively. Carcinoids developed in 27 of 100 inoculated and in 49 of 100 uninoculated male, and in 5 of 100 inoculated and in 21 of 100 uninoculated female animals at 18 months after inoculation. Adenocarcinoma developed in 1 of 100 male Mastomys in both the inoculated and uninoculated groups, but in none of the female animals in either the inoculated or uninoculated groups. These results indicate that antrum-predominant colonisation by H. pylori caused the decrease in incidence of carcinoid formation in Mastomys.
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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 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 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)