- Volume 7, Issue 4, 1974
Volume 7, Issue 4, 1974
- Short Articles
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Some Factors Affecting the Haemolytic Activity of Vibrio Cholerae
More LessSUMMARYThree-day nutrient-broth cultures of Vibrio cholerae gave distinct and reproducible results when tested for haemolysis of sheep RBC. As a medium for detecting haemolysis, heart-infusion broth was no better, and brain-heart-infusion broth was less satisfactory. Lack of reproducibility, and difficulty in interpreting results, were experienced when medium containing glycerol was used and when attempts were made to detect haemolysin in young (8-hour or 1-day) cultures. Horse and human RBC were found too fragile for this test.
Strains of V. cholerae could be separated into three biotypes: classical, El Tor, and an intermediate biotype to which many strains of the present pandemic belong. The latter strains are similar to the El Tor biotype but haemolysin negative. Hence, the haemolysin test, if performed by a reliable method, is a valuable epidemiological tool.
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- Articles
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Magnesium-Ion Susceptibility of Methicillin-Resistant Staphylococcus Aureus
More LessSUMMARYThe susceptibility to magnesium ion of 38 epidemiologically distinct strains of methicillin-resistant Staphylococcus aureus was investigated. Eighty-seven per cent were inhibited by 0.2m Mg++. None of 29 naturally-occurring methicillin-sensitive strains were inhibited by less than 0.3m Mg ++. Methicillin-resistant S. aureus strains were not especially susceptible to calcium ions. Neither a biochemical association nor genetic linkage was demonstrated between susceptibility to magnesium ion and resistance to methicillin. Susceptibility to magnesium ion, production of enterotoxin B, and inability to split Tween 80 were three unusual characteristics biochemically unrelated to methicillin resistance which were concomintantly present in 63% of methicillin-resistant S. aureus.
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Immunogenicity of the δ-Haemolysin of Staphylococcus Aureus
More LessSUMMARYAntibody to δ-lysin of Staphylococcus aureus was produced in rabbits given injections of purified antigen. Removal of normal serum inhibitors was effected by ammonium-sulphate fractionation and ion-exchange chromato-graphy. The purified anti-δ-lysin showed a single line of precipitation with purified antigen in Ouchterlony agar gel-diffusion tests and when subjected to immunoelectrophoresis. The line of precipitation also coincided with the zone of haemolysis caused by δ-lysin when the agar gel-diffusion test was performed in blood-agarose plates.
A plot of the data obtained in a quantitative precipitin test performed with purified antibody and δ-lysin showed a characteristic curve confirming their interaction; in control tests with non-immune sera in place of δ-antibody, no precipitation was evident.
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Candida Serology in Open-Heart Surgery
More LessSUMMARYSera from patients who had undergone open-heart surgery were examined for antibodies to Candida albicans by counter-immunoelectrophoresis, immuno-diffusion, immunofluorescence, and agglutination tests. No single test gave an absolute indication of systemic infection or endocarditis, although the immuno-diffusion procedure was the most specific test. A counter-immunoelectrophoresis test is recommended as a screening procedure, provided that positive results are confirmed by other techniques.
Postive serological findings in the absence of clinical endocarditis is probably due to transient fungaemia but should alert the clinician to the possibility that endocarditis may develop later. Serological monitoring should be continued for at least 3 years after cardiac surgery.
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Sequence of Structural Changes in Cultures of Clostridium Tetani Grown on a Solid Medium
More LessSUMMARYThe life cycle of a swarming culture of Clostridium tetani has been examined by light and electron microscopy. Onset of swarming is accompanied by cell elongation and nuclear multiplication without cellular division. As swarming progresses, the elongating bacteria produce a greatly increased complement of flagella; the nuclei are seen to be neatly and evenly distributed throughout the cytoplasm and not separated by cross-septa. These findings are discussed in the light of recent studies on the swarming of Proteus species.
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The Advantages of Hela Cells For Isolation of Rhinoviruses
More LessSUMMARYA sensitive line of HeLa cells was found to be better than two lines of diploid human embryo-lung (HEL) cells, WI-38 and MRC-5, for the isolation of several serotypes of rhinovirus from experimentally-infected volunteers. Comparative infectivity titrations of three rhinoviruses which were either un-adapted or only partly adapted to tissue culture confirmed the greater sensitivity of the HeLa cells. The substitution of foetal calf serum for non-foetal bovine serum in the tissue culture medium slightly enhanced the sensitivity of the HEL cells to rhino viruses but had no such effect on HeLa cells; HeLa cells nevertheless remained more sensitive than HEL cells. The line of HeLa cells studied merits more general use for the isolation of rhino viruses from clinical specimens.
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Separation and Purification of Enterotoxins From a Strain Escherichia Coli Pathogenic for Pigs
More LessSUMMARYEnterotoxin was produced by growing Escherichia coli strain PI6 (serotype 09; K9) in a defined medium. Ultrafiltration and gel-filtration studies suggested that toxic activity was produced by enterotoxins, 17, 27, 33 and 17% of which had, respectively, MW values of 5.9 × 105, 9.5 × HP, 6.7 × 103 and 380. Inactivation accounted for the remaining 6%. There was some evidence that toxin of MW 6.7 × 103 fragmented to produce toxin of MW 380.
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Reinvestigations of the Relationship Between Sporulation, Heat Resistance and Some Biochemical Properties in Strains of Clostridium Perfringens
More LessSUMMARYIsolates of Clostridium perfringens obtained from soil samples heated at 100°C and from samples heated at less than 100°C exhibited markedly different fermentation properties in tests with inositol, salicin, cellobiose, arbutin and aesculin. None of the C. perfringens isolates obtained from samples heated at 100°C for various lengths of time could ferment inositol, whereas all of the isolates obtained from unheated samples could ferment this sugar. The longer the preheating period at 100°C, the greater the number of aberrant isolates that attacked salicin, cellobiose, aesculin and arbutin, and the weaker were the sporulating abilities of these isolates. Most of the “heat-resistant” strains with attenuated sporulating abilities, however, could sporulate well when raffinose or melibiose was the only carbohydrate present in a test medium.
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The Effects of Chloramphenicol, Nalidixic Acid and Penicillin on the Growth and Division of Swarming Cells of Proteus Mirabilis
More LessSUMMARYWhen filamentous swarming cells of Proteus mirabilis were observed on the surface of agar, they were seen to divide asynchronously into short cells. Inhibition of DNA synthesis with nalidixic acid had no effect on the division for about 2 hours which allowed time for the potential number of divisions to occur. Inhibition of protein synthesis with chloramphenicol allowed only 2 or 3 divisions and division stopped after 45-60 min. Inhibition of murein synthesis with penicillin stopped division immediately, but elongation continued for 30-45 min. The cells then began to bulge and burst and there was disorganisation of the nuclear material. The implications of these observations with regard to the mechanism of production of swarming filaments in Proteus are discussed and it is concluded that a lesion associated with the swarming character is probably in the cell membrane.
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Antimicrobial Effectiveness of Kanamycin, Aminosidin, B8-K8, Sisomicin, Gentamicin and Tobramycin Combined with Carbenicillin or Cephalothin Against Gram-Negative Rods
More LessSUMMARYThe activity of kanamycin, aminosidin, BB-K8, sisomicin, gentamicin and tobramycin, has been compared in vitro against a variety of Gram-negative micro-organisms isolated from hospital patients. Clear differences in activity against Pseudomonas aeruginosa were observed between these antibiotics, tobramycin, BB-K8 and sisomicin being more active than the others. No major broadening of the spectrum occurred when carbenicillin and cephalothin were combined with the more active aminoglycosides, tobramycin, sisomicin and BB-K8. Synergism was observed against more than 50% of the strains of Ps. aeruginosa when BB-K8, tobramycin, sisomicin or gentamicin were combined with carbenicillin and against more than 50% of klebsiella strains when aminosidin, kanamycin or gentamicin were combined with cephalothin.
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Enterobacteria, β-Lactam Antibiotics and β-Lactamases in Clinical Practice
More LessSUMMARYStrains of enterobacteria isolated in a cardio-thoracic hospital and a rural general practice were collected for three years. The organisms were tested for sensitivity to four βlactam antibiotics, and the βlactamases from resistant strains were subsequently studied. There was no evidence of single-source infection with most of the strains.
Investigations were carried out on 1050 of the isolates. Eighty per cent, of the Escherichia coli and Proteus mirabilis cultures were sensitive to the two penicillins and two cephalosporins used and were omitted from further studies. The organisms resistant to 100 μg per ml of at least one of the four drugs were grouped taxonomically and the β-lactamases from 325 of them were examined. Relationships between the antibiotic resistance of the organisms and the substrate specificities and inhibitor profiles of their enzymes were studied. Seven β-lactam antibiotics were used to determine enzyme substrate-specificities and four for the inhibitor profiles. Enterobacter, Citrobacter, P. morgani and P. vulgaris were predominantly resistant to the cephalosporins and produced cephalosporinases that were inactivated by all the inhibitor compounds. Klebsiella, Esch. coli and P. mirabilis were mainly penicillin resistant. Klebsiella enzymes attacked penicillins and cephalosporins, but were not inhibited. The β-lactamases from Esch. coli strains showed a wide diversity of substrate degradation and inhibitor profiles, partly because of the frequency with which the enzyme activity was R-factor-mediated.
Most of the previously reported β-lactamases from enterobacteria were encountered among our organisms. The resistance patterns and enzyme types of the strains were well correlated with the generic groups of the producer organisms.
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The Antibody Responses in Man to Infection with Different Serotypes of Group-a Streptococci
More LessSUMMARYThe influence of the infecting serotype on streptococcal antibody response in man was investigated in a series of twelve incidents of streptococcal infection due to nine different M-types. The percentage of patients who developed type-specific M antibody after throat infection with opacity-factor-negative M-types varied between 64 and 100% and was in general three times greater than the percentage who developed this antibody to opacity-factor-positive M types. The type-specific antibody response was poor after skin infection with both opacity-factor-positive and opacity-factor-negative serotypes and varied between 0 and 33%.
Antistreptolysin O and anti-deoxyribonuclease B titres were on the whole similar in the different outbreaks, except that anti-streptolysin O titres were low and anti-deoxyribonuclease B titres were high in patients with skin infection.
The antibody response to M-associated protein varied widely between outbreaks. In incidents due to opacity-factor-positive serotypes, the titres were generally low, but opacity-factor-negative serotypes showed great variation in their ability to cause production of the antibody. In outbreaks of tonsillitis in which some of the patients later suffered from rheumatic fever, many persons formed large amounts of the antibody in response to an uncomplicated infection. Because high titres of antibody against M-associated protein are almost invariable in rheumatic fever it seems possible that the “rheumatogenic” strains of group-A streptococci are to be found among the opacity-factor-negative serotypes.
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Growth and Toxin Production of Tetanus Bacilli In Vivo
More LessSUMMARYThe vegetative growth of tetanus bacilli in vivo was examined in mice challenged intramuscularly with spores suspended in 4% CaCI2 solution. The viable count of organisms in material derived by grinding up the injection site was low at 6 hours and thereafter increased to counts of the order of 2×107 colony-forming units of Clostridium tetani in the ground-up lesion about 24 hours after inoculation. At that time the lesion volume was only about 1 ml.
In mice challenged with 1200 to 120,000 spores or in those given 2 MLD of toxin, the time taken for the resulting ascending tetanus to progress from its first appearance to become severe enough to prove fatal was similar-about 17 hours. For the infected mice and those challenged with toxin, however, the time of onset of the first signs of tetanus differed: it was 13 hours after inoculation of toxin, but 20 hours after injection of spores. It is suggested that the difference represents the time taken for the injected spores to form 2 MLD of toxin in the mouse, i.e., about 7 hours after challenge. At this time the numbers of viable organisms at the site of infection had not detectably increased, but rapid growth was about to begin.
These observations suggest that a lethal dose of tetanus toxin may be produced rapidly in an infected tissue by a very small number of viable organisms. Within 24 hours of challenge, a heavy growth of C. tetani may be present in a lesion only about 1 ml in volume.
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Ultrastructural Changes In Renal Tubules of Sheep Following Experimental Infection With Leptospira Interrogans Serotype Pomona
More LessSUMMARYSheep were experimentally infected with Leptospira interrogans serotype pomona and after 34 days the kidneys were examined by electron microscopy. Colonisation of the kidneys was well established at this time and changes in the kidney tubules included a concentration of leptospires around the periphery of the proximal tubular lumen. The microvilli making up the brush border were in some instances greatly reduced in numbers and in others the microvilli had developed bulbous ends. Necrotic epithelial cells within the tubules were observed and these were sometimes found free in the tubular lumen. The possible sequence of events leading to these changes is discussed.
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Antibiotic-Resistant Gram-Negative Bacilli in the Faeces of Neonates
More LessSUMMARYA total of 880 samples of faeces from 584 neonates in four hospitals were examined for the presence of antibiotic-resistant Gram-negative bacilli. The proportion of strains of Escherichia coli and Klebsiella spp. carrying R factors was also determined. Some resistant strains of E. coli and Klebsiella spp. were rapidly acquired after birth and the number of isolates increased in relation to the length of hospital stay. The proportion of isolates of Klebsiella spp. increased to over 60% in babies in special care units but increased to a lesser extent (less than 30%) in other wards. The four hospitals showed differences in the proportion of babies carrying antibiotic-resistant strains and this was partly attributable to the inclusion of samples from special care units in three of the hospitals. Antibiotic-resistant Gram-negative bacilli other than E. coli and Klebsiella spp. were isolated much less frequently. Transferable resistance was demonstrated in 49% of 208 resistant strains of E. coli and in only 6.5% of 240 strains of Klebsiella spp.
An increased frequency of resistant strains was found in babies associated with abnormal deliveries and in babies treated with antibiotics. Resistant strains were probably acquired initially from the mothers, but although there was evidence of cross-infection with E. coli and Klebsiella spp. particularly in special care units, no common source was identified.
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Rapid Group and Species Identification of Enterococci by Means of Tests With Pooled Phages
More LessSUMMARYPreliminary observations are reported on the use of phage pools for the group and species diagnosis of enterococci together in one test. Three principal pools were used, namely: (1) pool of 20 phages for group diagnosis, (2) pool of 17 phages for Streptococcus faecalis species diagnosis and (3) pool of 3 phages for S. faecium diagnosis.
By this method, 171 of 175 strains of enterococci isolated in the clinical laboratory (97.7%) were identified. A collection of standard group D strains showed different sensitivities according to species. The separate pools of phages for S. faecalis and for S. faecium can be used to distinguish between members of these two species, but this test is at present rather less sensitive than the test with the 20-phage pool.
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Variation in Polymyxin Sensitivity Among Colonies in Primary Plate Cultures of Vibrio Eltor
More LessSUMMARYTwenty colonies from each of 27 randomly selected primary cultures of cholera vibrios on bile-salt agar were investigated. All of the individual colonies comprised cholera vibrios that would be labelled as Vibrio eltor but they varied in their sensitivity to polymyxin. In 10 of the primary cultures, all of the colonies were of vibrios resistant to polymyxin B, and in another nine cultures all the colonies proved to be of organisms sensitive to the antibiotic. The remaining eight primary cultures were found to be mixtures of sensitive, partially sensitive and resistant colonies. The fact that all the individual colonies in the primary cultures examined were found positive for haemagglutination and resistance to cholera group-TV phage irrespective of their pattern of polymyxin sensitivity indicates that these two characters are not linked with resistance to polymyxin B.
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Haemophilus Vaginalis—Further Investigations Into Its Identity
More LessSUMMARYHaemophilis vaginalis strains isolated at Lewisham Hospital were shown to be anti-genically similar if not identical with those isolated by Gardner and Dukes (1955). No similarity was shown to exist between H. vaginalis and the strains of Haemophilus, Coryne-bacterium and Lactobacillus that were examined. Indirect fluorescent-antibody staining specifically demonstrated the presence of H. vaginalis in direct films of vaginal exudate. This agreed with the isolation of this organism from the same sources and could be used as a diagnostic procedure.
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Prevalence in Italy of Antibodies to A New Human Papovavirus (Bk Virus)
More LessSUMMARYSera from 453 healthy persons of various ages were examined by haemagglutination-inhibition and by immunofluorescence for antibodies to BK virus, a new human papovavirus. Both tests showed that antibody was common in the population and that a majority of the infections probably occurred in early childhood.
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Attempted Interspecific Transduction of Antibiotic Resistance in Staphylococci
More LessSUMMARYVarious methods were used in attempts to transduce antibiotic resistance from coagulase-negative to coagulase-positive staphylococci, but none was successful.
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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)