- Volume 43, Issue 1, 1995
Volume 43, Issue 1, 1995
- Editorial
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- Antimicrobial Agents
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Bactericidal activity of the new 4-quinolones DU-6859a and DV-7751a
More LessSummaryThe bactericidal activity of two new 4-quinolones, DU-6859a and DV-7751a, was investigated against strains of Escherichia coli, Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae and Enterococcus faecalis. DU-6859a and DV-7751a were more bactericidal than any 4-quinolone tested previously. Furthermore, DU-6859a was unique among 4-quinolones in being able to kill Ent. faecalis after incubation for only 3 h in nutrient broth. The bactericidal mechanisms of DV-7551a were similar to those of other 4-quinolones, but, uniquely, DU-6859a possessed additional bactericidal mechanisms against both Str. pneumoniae and Ent. faecalis. This may explain the unusually potent bactericidal activity of this agent against these species. These results show that DU-6859a is a unique extended-spectrum 4-quinolone, which should prove to be superior to established 4-quinolones.
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Susceptibility to β-Mactam agents of Yersinia enterocolitica biotype 4, serotype O3 isolated in various parts of the world
More LessSummaryForty-eight human isolates of Yersinia enterocolitica of biotype 4, serotype 03 from various parts of the world were examined for susceptibility to 13 β-lactam agents. The intracellular β-lactamases of each of the 48 strains were examined. Isolates from Europe, Asia and Brazil (phage type VIII) or South Africa and Hungary (phage type IXa) produced both enzyme A and enzyme B, whereas isolates from New Zealand and Australia (phage type IXb) lacked the cephalosporinase enzyme B. Among the seven strains isolated in Canada belonging to phage type IXb, three strains expressed only enzyme A (group I) whereas the other four strains produced both enzymes A and B (group II). The high susceptibility to the combination of amoxycillin and clavulanate observed in one subtype was explained by the absence of the cephalosporinase enzyme B. A simple disk diffusion test with this antibiotic combination was shown to be effective in the detection of enzyme B in Y. enterocolitica 4/O3.
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- Epidemiological Typing
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Clonal analysis of Haemophilus influenzae type b isolates in the United Kingdom
More LessSummaryStrains of Haemophilus influenzae type b were collected as part of an epidemiological study of bacterial meningitis in the North East Thames Region (NETR) of England. Subclones of H. influenzae were identified by outer-membrane protein typing and multilocus enzyme electrophoresis. These were compared with subclones of H. influenzae type b isolated from elsewhere in the UK. The subclone ET 12.5/OMP 3L was identified in 68% of isolates from cases of meningitis from the NETR. In the isolates from elsewhere in the UK, this subclone was identified in 79% of sterile-site isolates and 91 % of isolates from non-sterile sites. This subclone predominated in patients of different ages and from different ethnic groups, which suggests that non-Caucasians are infected with the subclone predominating locally. Since ET 12.5/OMP 3L subclone is the most abundant strain isolated in virtually all other Western European countries, these results provide additional evidence that the genetic diversity in the H. influenzae type b population in Europe is relatively restricted.
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Correlation of MAb subgroups with genotype in closely related Legionella pneumophila serogroup 1 strains from a cooling tower
More LessSummaryLegionella pneumophila serogroup 1 strains isolated from a cooling tower during the investigation of an outbreak of Legionnaires′ disease were shown previously to be related closely or indistinguishable by hybridisation-based restriction fragment length polymorphism analysis. However, these strains could be differentiated into five different MAb subgroups by comparison of their reactivity patterns with a recognised panel of monoclonal antibodies (MAbs). Pulsed-field gel electrophoresis (PFGE) of genomic fragments obtained after cleavage with rare-cutting restriction endonucleases also differentiated these strains. Four different restriction patterns were obtained with SfiI, EagI and SmaI, three restriction patterns with NotI, ApaI and SacII, and two patterns with Nael. Generally, the restriction patterns were related closely, differing in only one or two bands. The combined results of the restriction endonuclease digestions allowed the strains to be differentiated into groups that correlated to the MAb subgroups. Both PFGE patterns and MAb subgroups were found to be stable markers. The findings demonstrated that the MAb variability seen amongst the L. pneumophila serogroup 1 strains from this cooling tower was not solely phenotypic.
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- Clinical Microbiology
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Clinical and epidemiological features of an outbreak of acinetobacter infection in an intensive therapy unit
More LessSummarySporadic examples of infection with multi-resistant Acinetobacter spp. have occurred in Nottingham hospitals since at least 1977, punctuated by more prolonged outbreaks involving larger numbers of patients, particularly those confined to the intensive therapy unit (ITU) with severe underlying disease. In the most recent outbreak, 11 patients were infected with multi-resistant Acinetobacter strains and 26 patients were colonised. Four of the infected patients died directly or indirectly from infection with multi-resistant Acinetobacter spp., either while in the ITU or after discharge to a general ward. The mean interval from admission to the first isolation of a multi-resistant Acinetobacter strain was 6.7 and 12.1 days in the infected and colonised groups, respectively. Multi-resistant Acinetobacter strains were isolated most frequently from the respiratory tract, and eight patients had probable or suspected pneumonia caused by a multi-resistant Acinetobacter sp. All infected patients were treated with imipenem, with or without an aminoglycoside, except one patient who died before a diagnosis of acinetobacter infection was confirmed. Multi-resistant Acinetobacter spp. were isolated from various environmental sites in the ITU, and patient and environmental isolates were found to be related closely by biotyping, antibiograms, pulsed-field gel electrophoresis of chromosomal fingerprints and ribotyping. The outbreak was controlled ultimately by transfer of infected or colonised patients to an isolation cubicle, cohort nursing, emphasis on the importance of hand washing before and after patient contact and when handling case notes, and the use of disposable aprons and gowns during patient contact. These measures were combined with closure of the ITU for decontamination purposes on two separate occasions. Continued surveillance of ITU patients and occasional environmental sampling has proved to be important in preventing and controlling subsequent outbreaks of infection by this increasingly important nosocomial pathogen.
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A 13-year survey of bacteraemia due to β-haemolytic streptococci in a Danish county
More LessSummaryDuring 1981–1993, 229 episodes of bacteraemia due to β-haemolytic streptococci of groups A, B, C and G were diagnosed in the County of Northern Jutland, Denmark. The annual rates for bacteraemia were quite constant during the 13-year period for each streptococcal group. Group A streptococcal (GAS) bacteraemia was the most frequent, comprising 1.4% of all bacteraemias. The incidence of GAS bacteraemia was 1.8/100000/ year in children < 5 years of age-and 4.7/100 000/year in patients > 60 years old. With the notable exception of group B streptococcal (GBS) bacteraemia in neonates, β-haemolytic streptococci of groups B, C (GCS) and G (GGS) were isolated mostly from elderly patients. Except for GBS bacteraemia in neonates, approximately one-third of the bacteraemias in each group was nosocomially acquired. Predisposing factors included operative procedures in GAS and GCS bacteraemia, and diabetes mellitus in GBS bacteraemia. The skin was the most common primary focus in GAC, GCC and GGS bacteraemias, whereas the urinary tract was the commonest focus in GBS bacteraemia in adults. The mortality rates in GAS, GCS, GGS, and adult GBS bacteraemia were 23%, 16%, 17% and 19%, respectively. Of the 23 fatal cases of GAS bacteraemia, 57% died within 24h after blood cultures had been obtained.
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Rambach agar and SM-ID medium sensitivity for presumptive identification of Salmonella subspecies I–VI
More LessSummaryThe cultural characteristics of 112 Salmonella serovars belonging to subspecies I–VI were examined on Rambach agar and SM-ID medium. Colonies showing the typical red coloration were seen with 100 of 112 serovars assayed on SM-ID, and with 87 of 112 on Rambach agar. Atypical colourless colonies were observed on Rambach agar with ONPG-negative serovars S. Choleraesuis, S. Isangi, S. Typhi S. Worthington and S. Yoff of the subspecies I, S. II 52:d:e, n, x, z 15 of the subspecies II, 5. IV 6, 7: Z 4, z,24:- and S. IV 11:g, z51:-of the subspecies IV, and S. 40:z35: belonging to 5. bongori (V) species. Atypical blue, blue-green, blue-violet or violet colonies were observed on both media with all the ONPG-positive serovars of the subspecies IIIa (four of four strains) and IIIb (six of six strains) and with one of the two ONPG-positive (out of five) strains of the subspecies VI. Four serovars of S. bongori showed blue-green colonies on Rambach agar and typical red colonies on SM-ID, although they were all ONPG-positive. These results suggest that SM-ID medium is more sensitive than Rambach agar. However, the relatively low sensitivity of both media makes them suitable for use only in association with a traditional selective medium in both medical and environmental bacteriology, as well as for epidemiological purposes.
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- Models Of Infection
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An ascending non-obstructive model for chronic pyelonephritis in BALB/c mice
More LessSummaryChronic pyelonephritis was successfully produced in female BALB/c mice with Escherichia coli after introduction of the bacterial inoculum by the ascending route. E. coli strain 31-B, a nalidixic acid-resistant derivative of strain TN675 expressing type-1 pili, and E. coli strain BH-5, a mutant of 31-B, not expressing type-1 pili, were used in the model. Both the strains were able to induce chronic renal inflammation in the experimental animals. Whereas the initial colonisation was greater with strain 31-B, its non-pilate mutant BH-5 caused a significantly greater inflammatory response and also caused renal scarring observable 5 months after the infection.
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Dexamethasone treatment of lipopolysaccharide-induced meningitis in rabbits that mimics magnification of inflammation following antibiotic therapy
P. Rooney, G. Bilbe, O. Zak and T. O’reillySummaryThe objective of adjunct anti-inflammatory therapy of bacterial meningitis is the containment of heightened inflammation caused by lysis of bacteria by antibiotics. This can be modelled by giving two consecutive intra-cisternal injections of lipopolysaccharide (LPS) to rabbits, the first at 0 h to induce inflammation to mimic that occurring during the proliferation of bacteria in the cerebrospinal fluid (CSF). and the second at 6 h to mimic inflammation subsequent to antibiotic-induced bacterial lysis. Injection of 2.5 ng of LPS induced pleocytosis at 4 h which was preceded by a peak of tumour necrosis factor (TNF) activity at 2 h. A subsequent injection of 25 ng of LPS at 6 h induced second peaks of pleocytosis and CSF TNF. Dexamethasone (1.5 mg/kg, i.v.) administered 15 min or 1 h before the second injection of LPS tended only to reduce CSF TNF, but effectively prohibited further pleocytosis. Brain TNFα mRNA levels were unchanged at 6 and 7 h after LPS injection, and were unaffected by dexamethasone. These results indicate that the subarachnoid space is distinct from the general circulation in that the TNF-producing cells present do not display a hypo-responsive state towards LPS as occurs when LPS is injected systemically. Furthermore, dexamethasone is able to attenuate the secondary inflammatory response resulting from a second LPS injection without eliminating a second peak of TNF activity.
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- Technical Note
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Identification of urinary pathogens by the RAPIDEC™ur system
More LessSummaryA commercial method (RAPIDEC™ur; bio Mérieux UK Ltd, Basingstoke) and an in-house scheme based on conventional tests were compared for the identification of 179 commonly encountered gram-negative urinary pathogens. The methods identified correctly to genus level 97% and 84% of organisms, respectively. RAPIDEC ur was superior at identifying Escherichia coli, due to the detection of β-glucuronidase activity, but less cost-effective than the in-house scheme.
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- Case Report
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Campylobacter jejuni in the stomach
More LessSummaryCampylobacter jejuni is the commonest cause of acute bacterial enteritis in the UK. However, in this case a 74-year-old lady underwent gastroscopy for an upper gastrointestinal haemorrhage and was noted to have a gastric ulcer. Gastric biopsy revealed spiral gram-negative bacteria and culture yielded a moderate growth of C. jejuni. Identification was confirmed by growth characteristics, biochemical tests and PCR amplification of the species-specific flagellin gene—fla A. To prevent misidentification, it is important that laboratories routinely culturing gastric biopsies for Helicobacter pylori should perform a rapid urease test and not rely solely on microscopic morphology.
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- Bacterial Characterisation
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Denaturing gradient gel electrophoresis analysis for the detection of point mutations in the Chlamydia trachomatis major outer-membrane protein gene
More LessSummaryFifty clinical strains of Chlamydia trachomatis were studied by denaturing gradient gel electrophoresis (DGGE) of bacterial DNA amplified by the polymerase chain reaction (PCR). The strains belonged to the three most commonly encountered serovars in developed countries—D, E and F. Six reference strains, including the serovar Da strain, were also studied. The DNA sequences explored encompassed the four variable domains (VDs) of ompl, the gene encoding the major outer-membrane protein (MOMP). The corresponding regions in the MOMP contain the species-, subspecies- and serovar-specific epitopes. The four distinct serovars were clearly differentiated by specific migration pattern. No sequence variations were observed among strains of serovar F. However, variant strains within serovars D and E were found, which exhibited migration patterns different from those of the reference strains and these were sequenced directly. According to the observed sequence variations, serovar D strains could be divided into three stable representative groups (D, D1 and D2). Two variants were identified among serovar E strains. No biological differences were observed for the variant strains in terms of growth properties, ecology or pathogenicity. All the nucleotide substitutions detected in the VDs were non-synonymous at the protein level and, for the serovar D strains, could account for differences identified by specific monoclonal antibodies. These substitutions could be involved in antigenic drift, driven by the immune pressure of the host, leading to the emergence of serovariants. The data may explain, in part, chlamydial infection recurrences and could have critical implications for developing rational vaccine strategies.
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Iron supply of staphylococci and of micrococci by α-ketoacids
More LessSummaryMost of 232 strains of coagulase-negative staphylococci (CNS) belonging to 16 species, and nine strains of micrococci belonging to four species, could be distinguished by their growth on an iron-poor nutrient medium. α-Keto-/α-hydroxyacids, as primary metabolites, facilitated iron supply to CNS and micrococci under various iron-limited conditions, as detected by different bioassay methods. Twelve selected CNS strains and two micrococcal strains produced significant amounts of α-ketoacids in iron-poor liquid nutrient media. In particular, strains of Staphylococcus cohnii, S. xylosus and S. lentus unable to grow on iron-poor media, produced high amounts of pyruvic acid and α-ketoglutaric acid. In bioassays, the selected CNS strains being siderophore indicator strains were fed with α-ketoacids at different levels of iron limitation. Strains able to grow under iron deprivation appeared to produce additional siderophores such as staphyloferrins under iron stress, α-Keto-/α-hydroxyacids may be additionally active in the iron supply of CNS and micrococci.
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- Announcement
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- Books Received
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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 51 (2002)
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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)