- Volume 57, Issue 5, 2008
Volume 57, Issue 5, 2008
- Editorial
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- Review
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Roles of the plasticity regions of Helicobacter pylori in gastroduodenal pathogenesis
More LessPutative virulence genes of Helicobacter pylori are generally classified into three categories: strain-specific genes, phase-variable genes and genes with variable structures/genotypes. Among these, there has recently been considerable interest in strain-specific genes found outside of the cag pathogenicity island, especially genes in the plasticity regions. Nearly half of the strain-specific genes of H. pylori are located in the plasticity regions in strains 26695 and J99. Strain HPAG1, however, seems to lack a typical plasticity region; instead it has 43 HPAG1-specific genes which are either undetectable or incompletely represented in the genomes of strains 26695 and J99. Recent studies showed that certain genes or combination of genes in this region may play important roles in the pathogenesis of H. pylori-associated gastroduodenal diseases. Most previous studies have focused on the plasticity region in strain J99 (jhp0914–jhp0961) and the jhp0947 gene and the duodenal ulcer promoting (dupA) gene are good candidate markers for gastroduodenal diseases although there are some paradoxical findings. The jhp0947 gene is reported to be associated with an increased risk of both duodenal ulcers and gastric cancers, whereas the dupA gene, which encompasses jhp0917 and jhp0918, is reported to be associated with an increased risk of duodenal ulcers and protection against gastric cancers. In addition, recent studies showed that approximately 10–30 % of clinical isolates possess a 16.3 kb type IV secretion apparatus (tfs3) in the plasticity region. Studies on the plasticity region have only just begun, and further investigation is necessary to elucidate the roles of genes in this region in gastroduodenal pathogenesis.
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- Pathogenicity And Virulence
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dupA as a risk determinant in Helicobacter pylori infection
The Helicobacter pylori duodenal ulcer promoting (dupA) gene has been previously described as a risk marker for duodenal ulcer (DU) development and a protective factor against gastric cancer (GC). Recent studies which have assessed the application of dupA in the prediction of clinical outcomes have been controversial. In the current study, the association of dupA with the clinical outcomes and histopathological changes following H. pylori infection was evaluated in Iranian patients. A total of 157 H. pylori-infected patients with DU (n=30), gastric ulcer (n=23), gastritis (n=68) or GC (n=36) were assessed. The presence of jhp0917 and jhp0918 genes was determined by gene specific PCR. Gastric histopathological changes were recorded according to the updated Sydney system. Seventy-eight (49.7 %) and 71 (45.2 %) of the 157 tested strains, respectively, were positive and negative for both genes. The remaining 8 (5.09 %) of the 157 strains were jhp0917-positive/jhp0918-negative. Univariate analysis showed inverse associations between dupA and histological features including dysplasia as the penultimate stage of GC and lymphoid follicles as a consequence of relatively long-standing H. pylori-associated gastritis. The degrees of nucleotide sequence identity of Iranian strains to Colombian, Brazilian and Indian strains ranged from 86.1 to 100 % for the aligned regions of jhp0917, from 88 to 98.8 % for jhp0918 and from 93.4 to 99.5 % for the partial sequences of the dupA gene. Despite the fact that possession of the dupA gene showed no association with any disease category in our population as reported in several other countries, association of dupA-negative strains of H. pylori with pre-malignant lesions calls for additional studies to evaluate the role of this gene as a protective marker against GC.
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Signal-mediated interactions between Pseudomonas aeruginosa and Candida albicans
More LessPseudomonas aeruginosa causes infections in a wide variety of hosts and is the leading cause of mortality in cystic fibrosis (CF) patients. Although most clinical isolates of P. aeruginosa share common virulence determinants, it is known that strains evolve and change phenotypically during CF lung infections. These changes can include alterations in the levels of N-acyl homoserine lactones (HSLs), which are secreted signal molecules. In the CF lung, fungi, especially Candida albicans and Aspergillus fumigatus, may coexist with P. aeruginosa but the implications for disease are not known. Recent studies have established that signalling can occur between P. aeruginosa and C. albicans, with the bacterial molecule 3-oxo-C12HSL affecting Candida morphology, and the fungal metabolite farnesol reducing levels of the Pseudomonas quinolone signal and pyocyanin in Pseudomonas. Whether these interactions are common and typical in clinical strains of P. aeruginosa was addressed using CF isolates that produced varied levels of HSLs. It was found that, whereas some clinical P. aeruginosa strains affected C. albicans morphology, others did not. This correlated closely with the amounts of 3-oxo-C12HSL produced by the isolates. Furthermore, it was established that signalling is bidirectional and that the C. albicans molecule farnesol inhibits swarming motility in P. aeruginosa CF strains. This work demonstrates that clinical isolates of these opportunistic pathogens can interact in strain-specific ways via secreted signals and illustrates the importance of studying these interactions to fully understand the microbial contribution to disease in polymicrobial infections.
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Identification of hyperinvasive Campylobacter jejuni strains isolated from poultry and human clinical sources
Campylobacter jejuni causes gastroenteritis with a variety of symptoms in humans. In the absence of a suitable animal model, in vitro models have been used to study virulence traits such as invasion and toxin production. In this study, 113 C. jejuni isolates from poultry and poultry-related (n=74) environments as well as isolates from human cases (n=39) of campylobacteriosis and bacteraemia were tested for invasiveness using INT 407 cells. The method was sufficiently reproducible to observe a spectrum of invasiveness amongst strains. As a result, strains were classified as low, high and hyper-invasive. The majority of strains (poultry and human) were low invaders (82 % and 88 %, respectively). High invasion was found for 5 % of human strains and 11 % of poultry-related isolates. However, only 1 % of poultry strains were classified as hyperinvasive compared to 13 % of human isolates (P=0.0182). Of those isolates derived from the blood of bacteraemic patients, 20 % were hyperinvasive, though this correlation was not statistically significant. An attempt was made to correlate invasiveness with the presence of seven genes previously reported to be associated with virulence. Most of these genes did not correlate with invasiveness, but gene cj0486 was weakly over-represented, and a negative correlation was observed for the gene ciaB. This trend was stronger when the two genes were analysed together, thus ciaB− cj0486 + was over-represented in high and hyperinvasive strains, with low invaders more commonly found to lack these genes (P=0.0064).
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- Host Response
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Mycobacterium tuberculosis co-existence with humans: making an imprint on the macrophage P2X7 receptor gene?
More LessThe development of tuberculosis (TB) infection in humans depends on the mycobacterial strain and the human host, and is multigenically controlled in both. ATP ligation of P2X7 receptors expressed on human macrophages infected with mycobacteria induces cell death and subsequent loss of intracellular bacterial viability. This study analysed the allelic distribution of two single-nucleotide polymorphisms (SNPs) in the P2RX7 gene in the Slavic population of the St Petersburg area of Russia. Analysis of the −762 C/T P2RX7 promoter SNP revealed no significant association between pulmonary TB patients and control subjects (3×2 χ 2=3.2, 1 d.f., P=0.2). The −762C allele was highly and almost equally represented in both groups in this study (68.2 % in patients and 69.3 % in controls). This result differs strikingly from a Gambian study where this allele was found in only 7 and 12 % of pulmonary TB patients and controls, respectively [Li, C. M., Campbell, S. J., Kumararatne, D. S., Bellamy, R., Ruwende, C., McAdam, K. P. W. J., Hill, A. V. S. & Lammas, D. A. (2002). J Infect Dis 186, 1458–1462]. In contrast, the frequency of the C allele at position 1513 in exon 13, resulting in a loss of P2X7 function, was significantly higher among pulmonary TB patients in this study (P=0.02). Thus, analysis of the P2X7 receptor gene in the Russian Slavic population showed that the 1513C allele, acting dominantly, is a possible risk factor for clinical TB, whereas the −762 P2RX7 polymorphism did not appear to be associated with human susceptibility to TB.
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- Diagnostics, Typing And Identification
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Analysis of Helicobacter pylori isolates from Chile: occurrence of selective type 1 Lewis b antigen expression in lipopolysaccharide
Previous studies have shown that the LPS of Helicobacter pylori isolated from North American and European hosts predominantly expresses type 2 Lewis x (Lex) and Ley epitopes, whilst the LPS from Asian strains has the capacity to express type 1 Lea and Leb structures. The aim of this study was to evaluate the expression of Le antigens and the cytotoxin-associated antigen (CagA) by H. pylori isolates from Chile. A total of 38 isolates were screened. The expression of Le antigens and CagA was determined by whole-cell indirect ELISA, using commercially available monoclonal anti-Le and polyclonal anti-CagA antibodies. LPS profiles of H. pylori isolates were assessed by gel electrophoresis and Western blotting. Expression of Lex and/or Ley epitopes was confirmed in 32/38 isolates (84 %), whilst 9/38 isolates (24 %) expressed type 1 Leb blood group determinants, in addition to type 2 Lex and Ley structures. Six strains (16 %) were non-typeable. The majority of H. pylori strains examined were CagA-positive (83.3 %).
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Identification of dermatophytes by sequence analysis of the rRNA gene internal transcribed spacer regions
Identification of dermatophytes using the traditional method is sometimes problematic because of atypical microscopic or macroscopic morphology. The aim of this study was to evaluate the feasibility of using sequencing of the ribosomal internal transcribed spacer (ITS)1 and ITS2 regions for identification of 17 dermatophyte species. The ITS regions of 188 strains (62 reference strains and 126 clinical isolates) were amplified by PCR and sequenced. Species identification was made by sequence comparison with an in-house database comprising ITS sequences of type or neotype strains or by blast searches for homologous sequences in public databases. Strains producing discrepant results between conventional methods and ITS sequence analysis were analysed further by sequencing the D1–D2 domain of the large-subunit rRNA gene for species clarification. The identification rates by ITS1 and ITS2 sequencing were higher than 97 %. Based on reference sequences of type or neotype strains, it was noted that most strains of Trichophyton mentagrophytes were misidentifications of Trichophyton interdigitale. In addition, barcode sequences were present in species of the Microsporum canis complex and Trichophyton rubrum complex. These barcode sequences are useful for species delineation when the results of ITS sequencing are ambiguous. In conclusion, ITS sequencing provides a very accurate and useful method for the identification of dermatophytes.
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Molecular diagnosis of sepsis in neutropenic patients with haematological malignancies
The rapid diagnosis of an infectious cause in the course of fever of unknown origin plays a pivotal role in the correct management of neutropenic patients. In this study, blood samples from febrile oncohaematological patients were tested using a novel commercial real-time PCR assay (LightCycler SeptiFast; Roche Molecular Systems) and blood culture (BacT/Alert 3D; bioMérieux). Twenty-one (20.4 %) and 34 (33 %) of the 103 samples under study tested positive by blood culture and PCR, respectively. The analysis of concordance evidenced a low correlation between the two approaches (83 %), mainly due to samples that tested negative by culture but positive using the molecular approach. Among 14 discordant cases negative by culture but positive by PCR, 12 were observed in sequential samples of patients with initial concordant results on samples drawn before the administration of a specific antimicrobial therapy. Moreover, DNA of a fastidious organism, Aspergillus fumigatus, not easily detectable by the cultural approach was rapidly detected in the two remaining discordant cases. Overall, the characteristics featured by the molecular method could be of interest in the development of new algorithms for the diagnosis of sepsis in critical patients.
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Evaluation of the GenoType Mycobacteria Direct assay for the simultaneous detection of the Mycobacterium tuberculosis complex and four atypical mycobacterial species in smear-positive respiratory specimens
A novel, commercially available reverse hybridization assay [GenoType Mycobacteria Direct (GTMD), version 2.0; Hain Lifescience] was evaluated for the direct detection of five clinically relevant mycobacterial species [Mycobacterium tuberculosis complex (MTBC), Mycobacterium avium, Mycobacterium malmoense, Mycobacterium kansasii and Mycobacterium intracellulare] from 54 smear-positive respiratory specimens and the findings were compared with culture results. Three approaches were used for specimen preparation using either whole or ‘split’ sample volumes and N-acetyl-l-cysteine/3 % NaOH or 4 % NaOH as decontamination chemicals. Forty-three out of 52 samples in which RNA amplification was successful gave GTMD results that concurred with the identification of the cultured isolate. All cases of MTBC were detected. Twenty-two samples contained M. tuberculosis complex, seven had M. kansasii, four had M. malmoense, seven contained atypical mycobacteria other than those detectable using the GTMD assay and three specimens contained no viable mycobacteria. The assay is easy to use and can be completed in one working day. Results interpretation is facilitated by the inclusion of an internal amplification control with each sample to allow identification of specimens containing amplification inhibitors. A positive GTMD result will quickly identify patients with MTBC infection or provide specific identification of four other atypical mycobacteria from the same specimen. This allows more rapid drug susceptibility testing, treatment, and public health and infection control decisions.
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Distribution of spa types among meticillin-resistant Staphylococcus aureus isolates during a 6 year period at a low-prevalence university hospital
More LessThis study describes the distribution and frequencies of strain types by protein A-encoding gene (spa) typing among a total of 200 meticillin-resistant Staphylococcus aureus (MRSA) single-patient isolates collected between 2000 and 2005 at the University Hospital Basel, Switzerland. Nine frequent spa types accounted for 49.5 % of MRSA isolates, whereas spa type t041 (15 % of all isolates) belonged to a local epidemic strain that is also a common strain type in southern Germany. Successful control of the outbreak strain was documented by epidemiological data and confirmed by spa typing results. The spa type t044 (3.5 %), corresponding to a widely disseminated European community-acquired MRSA (CA-MRSA), was first observed in 2002. The well-known CA-MRSA USA300 clone was detected in four patients (2 %). Sporadic strains occurring less than four times (32 different spa types) accounted for 23 % of isolates. No predominant spa type was seen, indicating a great genetic diversity. Only 34.5 % of patient isolates were acquired nosocomially. The presence of one or more of ten common virulence genes was shown in 79 % of strains. It was demonstrated that the sequence-based spa typing method allows analysis of local MRSA epidemiology in relation to other regions and countries over time.
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- Clinical Microbiology And Virology
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Selective antimicrobial activity of maggots against pathogenic bacteria
More LessMaggot therapy, also known as biosurgery, is an ancient method for the healing of chronic infected wounds. Although clinicians have reported on the beneficial activities of the Lucilia sericata larvae that have been used for healing chronic wounds, the selectivity of this therapy against the different pathogenic micro-organisms that are found in chronic wounds has never been analysed. In the present study, we have investigated the in vitro activities of larval excreta/secreta both against selected bacterial strains that frequently occur in chronically infected wounds, and against bacteria isolated directly from the larvae and their excreta/secreta. Additionally, the antibacterial activities were investigated in in vivo studies, by comparing bacterial diversity in wounds before and after the application of L. sericata larvae. In conclusion, larval therapy is highly recommended, particularly for the treatment of wounds infected with Gram-positive bacteria, like Staphylococcus aureus, but less so for wounds infected with Gram-negative bacteria, especially Proteus spp. and Pseudomonas spp. strains. Bacteria from the genus Vagococcus were resistant to the maggot excreta/secreta.
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- Oral Microbiology
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Frequency and expression of mutacin biosynthesis genes in isolates of Streptococcus mutans with different mutacin-producing phenotypes
More LessThe aim of this study was to analyse the frequency and expression of biosynthesis genes in 47 Streptococcus mutans isolates with different mutacin-producing phenotypes. Detection of the frequency and expression of genes encoding mutacin types I, II, III and IV were carried out by PCR and semi-quantitative RT-PCR, respectively, using primers specific for each type of biosynthesis gene. In addition, a further eight genes encoding putative bacteriocins, designated bsm 283, bsm 299, bsm 423, bsm 1889c, bsm 1892c, bsm 1896, bsm 1906c and bsm 1914, were also screened. There was a high phenotypic diversity; some Streptococcus mutans isolates presented broad antimicrobial spectra against other Streptococcus mutans clinical isolates, including bacteria resistant to common antibiotics, as well as Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Streptococcus pyogenes. The expression frequency of the bsm gene was higher than that of the previously characterized mutacins (I–IV). There was no positive correlation between the number of indicator strains inhibited (antimicrobial spectra) and the number of biosynthesis genes expressed (Spearman correlation test, r=−0.03, P>0.05). In conclusion, the high diversity of mutacin-producing phenotypes, associated with high frequency of expression of the biosynthesis genes screened, reveals a broad repertoire of genetic determinants encoding antimicrobial peptides that can act in different combinations.
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The prevalence of periodontopathogenic bacteria in saliva is linked to periodontal health status and oral malodour
More LessThis study investigated whether an improvement in periodontal health resulted in changes in the prevalence of periodontopathogenic bacteria in saliva and tongue coatings and a reduction in volatile sulfur compounds (VSCs: H2S and CH3SH) linked to oral malodour. The subjects were 35 patients who visited the breath odour clinic of Kyushu Dental College, Japan. Their mean age was 51.2±18.3 years (mean±sd). A clinical examination performed at baseline and 2 months after periodontal treatment assessed VSCs in mouth air using gas chromatography, periodontal probing depth and bleeding on probing (BOP) in all subjects; saliva and tongue coatings were also collected. Genomic DNA was isolated from the samples, and the proportions of five periodontopathogenic bacteria (Porphyromonas gingivalis, Tannerella forsythensis, Treponema denticola, Prevotella intermedia and Prevotella nigrescens) were investigated using quantitative real-time PCR. The subjects were classified into four groups based on the presence of a periodontal pocket of more than 4 mm (PD) and VSCs above the organoleptic threshold level (VSCT) as follows: –PD/–VSCT group, subjects without PD or VSCT; –PD/+VSCT group, those without PD but with VSCT; +PD/–VSCT group, those with PD but without VSCT; and +PD/+VSCT group, those with PD and VSCT. Although the mean PD values in the +PD/–VSCT and +PD/+VSCT groups, BOP in the +PD/+VSCT group, and H2S and CH3SH concentrations in the –PD/+VSCT and +PD/+VSCT groups were greater than in the other groups at baseline, we found no significant difference among the four groups after periodontal treatment. The proportion of periodontopathogenic bacteria in saliva was higher in the +PD/–VSCT and +PD/+VSCT groups than in the –PD/–VSCT and –PD/+VSCT groups at baseline and after treatment, but the proportions of bacteria in saliva after treatment were reduced compared to the baseline. Furthermore, the differences in the proportions of the five target bacteria in the tongue coating were not as apparent as those in saliva at baseline or after treatment. The prevalence of periodontopathogenic bacteria in saliva may reflect periodontal health status and influence VSC levels in mouth air.
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Extracellular proteolytic activities expressed by Bacillus pumilus isolated from endodontic and periodontal lesions
More LessThe purpose of the present study was to identify 12 Bacillus isolates that had been obtained from root canals of teeth requiring endodontic therapy and from periodontal pockets in severe marginal periodontitis, and to determine whether these isolates exhibited extracellular proteolytic activity and, using in vitro assays, whether any such activity could degrade substrates that would be pathophysiologically relevant with regard to the production of endodontic and periodontal lesions. Biochemical and carbohydrate fermentation patterns were used in the identification of all strains, which was confirmed by determination of the16S rRNA gene sequence for strain BJ0055. Screening for production of extracellular proteolytic activity by all strains was done with a general proteinase substrate. All isolates were identified as representing Bacillus pumilus and all exhibited extracellular proteolytic activity. The putative pathophysiological relevance of extracellular proteinase production in strain BJ0055 was assessed using fluorophore-labelled elastin and collagen and several chromogenic peptides. Probable classes of proteinases acting on each substrate were investigated using class-specific inhibitors. Activity–pH profiles were determined in buffers at different pH values. Extracellular activities that were caseinolytic, elastinolytic, collagenolytic, glutamyl endopeptidase-like, and alanyl tripeptidyl peptidase-like were observed. No trypsin-like activities were detected. Serine- and chymotrypsin-like serine proteinase activities were detected, with activity observed at neutral and alkaline, but not acidic, pH. B. pumilus strains isolated from endodontic and periodontal lesions exhibited extracellular activities that degrade elastin, collagen and other substrates. These activities may be virulence factors that contribute to tissue damage in apical periodontitis and severe marginal periodontitis.
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- Case Reports
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Cervical spondylodiscitis with spinal epidural abscess caused by Aggregatibacter aphrophilus
Spondylodiscitis caused by Aggregatibacter aphrophilus, formerly known as Haemophilus paraphrophilus, is an unusual condition and can be very difficult to diagnose. We report a case of cervical spondylodiscitis complicated by spinal epidural abscess in a 63-year-old woman, without underlying predisposing conditions. The source of infection was identified as a periodontal infection. The patient was successfully treated with systemic antibiotics.
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Post-operative mediastinitis, pleuritis and pericarditis due to Mycoplasma hominis and Ureaplasma urealyticum with a fatal outcome
Post-sternotomy mediastinitis, although infrequent, is a potentially life-threatening complication of cardiac surgery. We report an unusual case of Mycoplasma hominis and Ureaplasma urealyticum post-surgical mediastinitis with persistent pleural and pericardial effusion. Clinical manifestations and response to therapy are described, and the difficulties of establishing the diagnosis are discussed.
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Severe course of rat bite-associated Weil's disease in a patient diagnosed with a new Leptospira-specific real-time quantitative LUX-PCR
Leptospirosis is a zoonotic disease with global distribution, caused by spirochaetes of the genus Leptospira. Transmission of Leptospira interrogans serovar Icterohaemorrhagiae, the causative agent of Weil's disease, to humans usually results from exposure to the urine of infected, but mostly asymptomatic, rodents, either by direct contact or indirectly through contaminated soil or water. Although regarded as a re-emerging infectious disease, human leptospirosis is probably underdiagnosed due to its often unspecific clinical appearance and difficulties in culturing leptospires. Therefore, more rapid and specific diagnostic procedures are needed. Here we describe a novel real-time quantitative PCR system developed for the accurate and fast diagnosis of pathogenic Leptospira spp. Its usefulness in the management of a patient with rat bite-associated multiorgan failure is demonstrated.
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Mycobacterium chelonae empyema in an immunocompetent patient
More LessThoracic empyema caused by rapidly growing mycobacteria (RGM) and complicated with bronchopleural fistula is rarely reported, especially in immunocompetent patients. A 53-year-old healthy woman presented initially with a productive cough and intermittent fever. The patient received a complete treatment course following an initial diagnosis of pulmonary tuberculosis. After the anti-tuberculosis agents were discontinued, a right thoracic empyema with bronchopleural fistula occurred, and the pathogens from both pus and sputum were identified as Mycobacterium chelonae. Thoracotomy with decortication and wedge resection of the right middle lung was performed, followed by clarithromycin plus ciprofloxacin therapy for 36 months. This patient has not suffered a relapse in the last 3 years. In addition to the experience of successful treatment, this case indicates that RGM such as M. chelonae can emerge as causative pathogens of thoracic empyema, even in healthy persons.
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A rare presentation of ventriculitis and brain abscess caused by Fusobacterium nucleatum
More LessAnaerobic ventriculitis is rare, and usually seen in patients with predisposing factors such as otitis media, mastoiditis, sinusitis or recent neurosurgery. We report what we believe to be the first case of ventriculitis and brain abscess due to Fusobacterium nucleatum infection in a man with no significant predisposing factors. He was successfully treated with antibiotic therapy.
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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)