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Volume 38,
Issue 6,
1993
Volume 38, Issue 6, 1993
- Articles
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Co-Agglutination (Co-A) Test for Circulating Antigen in Hydatid Disease
More LessSummaryA co-agglutination (Co-A) test with Staphylococcus aureus (Cowan's strain I) bearing protein A coated with specific hydatid antibodies, was used to demonstrate circulating hydatid antigen in serum for the diagnosis of hydatid disease. The test had a sensitivity of 95% and a specificity of 89%in detecting hydatid antigen in serum. A false positive reaction was observed with 18·5%of control sera from patients with various parasitic diseases. However, these all gave negative results when tested after further dilution. The test is reliable and rapid; the result could be obtained within 30-45 min of receipt of a serum sample. Since the test is simple and the reagents are inexpensive and easily available, it can be used in less well equipped laboratories in developing countries.
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Induction of Inflammatory Cytokines by a Soluble Moiety Prepared from an Enzyme Lysate of Actinomyces Viscosus Cell Walls
More LessSummaryA carbohydrate-rich and immunobiologically active component, M1Av, was prepared from an M-1 endo-N-acetylmuramidase digest of cell walls of Actinomyces viscosus ATCC 19246 by CM Sephadex C-25 and Sephadex G-100 chromatography. M1Av stimulated thioglycolate-induced peritoneal macrophages from C3H/HeN and C3H/HeJ mice to release cell-free tumour necrosis factor (TNF) and interleukin (IL)-6, and a cell-associated thymocyte activating factor, probably IL-1. An intravenous (i.v.) injection of M1Av induced increased levels of TNF and IL-6 in the serum of C3H/HeN mice that had been primed with 100 µg of muramyldipeptide (MDP) i.v. However, M1Av did not induce TNF release in C3H/HeJ mice similarly primed with MDP. Simultaneous administration of M1Av (100 κg, i.v.) and galactosamine (18 mg, intraperitoneally) killed C3H/HeN, but not C3H/HeJ mice. M1Av was shown to be practically free of endotoxin by the Limulus test. These findings indicate that the solubilised A. viscosus cell-wall carbohydrate moiety induced inflammatory cytokines both in vitro and in vivo.
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Sensitisation of Cariogenic Bacteria to Killing by Light From a Helium-Neon Laser
More LessSummarySuspensions of the cariogenic bacteria Streptococcus mutans, S. sobrinus, Lactobacillus casei and Actinomyces viscosus were exposed to light from a 7·3-mW heliumneon laser in the presence of toluidine blue O. A substantial killing rate (c. 106 cfu) of all four species was achieved with a dye concentration of 50 µg/ml and a light energy dose of 33·6 J/cm2. This was achieved in 60 s, an exposure time that is clinically acceptable. Exposure to laser light in the absence of the dye did not significantly affect the viability of any of the organisms. This approach may be useful in dentistry to sterilise a carious lesion prior to its repair.
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Prevalence of Treponema Denticola and Porphyromonas Gingivalis in Plaque From Periodontally-Healthy and Periodontally-Diseased Sites
More LessSummaryIntracrevicular plaque from periodontally-healthy individuals who had refrained from oral hygiene measures for 24 h prior to sampling, and subgingival plaque from diseased sites of patients with chronic periodontitis were screened by ELISA for the presence of Porphyromonas gingivalis and Treponema denticola. The samples were also subjected to the PerioScan test to detect the presence of enzymes capable of degrading N-benzoyl-DL-arginine-2-naphthylamide (BANA). Of the 141 samples from periodontally-healthy sites, 73% contained T. denticola antigens and 78% P. gingivalis antigens, compared to 43% and 59%, respectively, in plaque samples from the 159 diseased sites. A positive reaction in the PerioScan test was obtained in 89% of plaque samples from diseased sites and in 60% of those from healthy sites. The correlation between the results of the two assays was poor in the case of intracrevicular plaque from healthy sites. However, with plaque samples from diseased sites, the results of the PerioScan test showed very strong correlation with those obtained with the ELISA, suggesting that the former may be a useful, rapid means of indicating the presence of T. denticola and P. gingivalis in such plaque samples.
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Confocal Laser Scanning Microscopy of Peritoneal Catheter Surfaces
More LessSummarySurface topography of used (in situ > 12 months) and unused CAPD catheters was studied by scanning electronmicroscopy (SEM) and confocal laser scanning microscopy (CLSM). Microbial biofilm was observed on all used catheters. Disruption and removal of the attached biofilm revealed extensive pitting of the catheter surface and scoring within the catheter pores. Similar, though less extensive, surface defects were present in unused catheters. Examination by CLSM, with software specific to the determination of surface topography, showed used catheters to have a surface microrugosity greater than that of unused catheters (p > 0·0005). Adherence studies with radiolabelled Staphylococcus epidermidis demonstrated increased adherence to used than to unused catheters (p > 0·0005) after 48 h. However, when catheters were pre-treated with spent dialysate there was a substantial reduction in bacterial adherence to either catheter and no significant difference in adherence to used and unused catheters. Surface microrugosity of CAPD catheters increases during use but is unlikely to be an important factor in bacterial adherence in vivo.
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The Morphology of Chlamydia Pneumoniae
More LessSummaryThe morphology of a recently isolated strain of Chlamydia pneumoniae, YK-41, was compared by electronmicroscopy with C. pneumoniae TWAR, Chlamydia trachomatis L2/434/Bu and Chlamydia psittaci Cal 10. The results showed that “pear-shaped” morphology was not typical of C. pneumoniae. Basic morphological features, such as surface projections and hexagonally arrayed, regular structures in the inside layer of the outer membrane of elementary bodies, were very similar in these strains. The structure of strain YK-41 was identical with that of C. trachomatis and C. psittaci, but the profiles of elementary bodies were different from those of C. pneumoniae TWAR strains.
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Comparison of Different Primer Sets for Detection of Chlamydia Trachomatis by the Polymerase Chain Reaction
SummaryThe sensitivity and specificity of the polymerase chain reaction (PCR) method was studied in vitro with HeLa cells infected with Chlamydia trachomatis serovar L2. Three different primer sets were studied; they were derived from the endogenous plasmid, the non-variable part of the MOMP gene and the 16S ribosomal RNA (rRNA) gene. The plasmid primers were the most sensitive in the PCR method and detected at least 0·1 infectious unit of C. trachomatis in the presence of a superfluous amount of human DNA. Application of this plasmid PCR to 13 C. trachomatis culture-positive cervical smears containing < 10-> 200 inclusion-forming units showed that it was the most sensitive of the three methods and detected C. trachomatis in all samples. This correlates with the observation that the plasmid PCR method could detect C. trachomatis in cervical smears of four symptomatic patients for up to 3 weeks after the start of treatment with doxycycline. In contrast, the MOMP gene-and rRNA gene-directed PCR, as well as culture and direct immunofluorescence, gave negative results within 1 week. Therefore, we conclude that the plasmid primers are the best candidates for use in the PCR method in C. trachomatis screening programmes and clinical follow-up studies.
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Serogroup F Strains of Clostridium Difficile Produce Toxin B but not Toxin A
More LessSummaryMost toxigenic strains of Clostridium difficile produce two toxins: An enterotoxin (toxin A) and a cytotoxin (toxin B). Only one strain (strain 8864) has been reported to produce toxin B but no toxin A. Serogroup F strains (44) of C. difficile, often isolated from asymptomatic infants, have been examined for toxin production. These strains, which were from distinct geographical and clinical sources, did not produce any detectable toxin A in vitro when examined in three distinct immunoassays. Nevertheless, all the strains produced a cytotoxin. Immunological differences between the cytotoxin of the serogroup F strains and that produced by C. difficile strain VPI 10463 (serogroup G) were demonstrated with monoclonal antibodies specific for either the toxin B produced by C. difficile strain VPI 10463 or C. sordellii lethal toxin (LT). Polymerase chain reaction amplification with primers derived from C. difficile strain VPI 10463 toxin A and B genes showed that serogroup F strains seem to possess a toxin B gene homologous with that of strain VPI 10463 and at least fragments of the toxin A gene. When axenic mice were inoculated with serogroup F strains, the animals survived; they did not develop diarrhoea and no toxin A could be detected in their faeces. However, cytotoxin was detected. Furthermore, these mice were protected against subsequent challenge with the otherwise lethally toxigenic C. difficile strain VPI 10463. The serogroup F strains appeared to be homogeneous and distinct from other C. difficile strains with regard to toxin production.
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Alteration of Transfer Ribonucleic Acid of Neisseria Meningitidis During Growth in the Presence of Human Transferrin
More LessSummaryIron-related tRNA alterations have been shown to occur in several pathogens but nothing has been reported about the effect of iron on meningococcal tRNA. The chromatographic elution profile of 3H-tryptophan-tRNAtrp from a Neisseria meningitidis strain grown under different conditions was examined. The profile showed an early (P1) and a late (P2) eluting species of tRNAtrp, but the proportion of the two species varied under different growth conditions. The elution profile of trp-tRNAtrp from bacteria grown in iron-sufficient Mueller Hinton broth yielded a minor P1 species and a major P2 species, whereas under iron-restricted growth induced by desferrioxamine, the pattern was one of a major P1 species and minor P2 species. Iron-restriction induced by human transferrin (HTF) resulted in almost equal amounts of the two tRNAtrp species (P1 ? P2). Differences in the proportions of the tRNA species were also found between cells grown in liquid medium (P1 < P2) and on the same medium solidified with agar (P1 > P2). The growth phase of the bacteria did not have any effect on the tRNAtrp elution profile. Changes in tRNAtrp induced by HTF were readily and completely reversible when the cells were transferred to an iron-rich medium, but those induced by desferrioxamine remained irreversible for a long period (16 h) after such transfer.
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Diagnosis of Pneumocystis Carinii Pneumonia: Specificity and Sensitivity of Polymerase Chain Reaction in Comparison with Immunofluorescence in Bronchoalveolar Lavage Specimens
SummaryDNA amplification by the polymerase chain reaction (PCR) is a promising method for the detection of Pneumocystis carinii in immunosuppressed patients. The sensitivity and specificity of the PCR technique has been assessed in comparison with the immunofluoresence method (IF) on bronchoalveolar lavage fluid (BALF). Results correlated in 43 (78·8%) of 52 cases studied. P. carinii PCR gave positive results with BALF from all 32 patients found to have P. carinii pneumonia (PCP); IF gave positive results with 26 of them. PCR was more sensitive and as specific as IF. However, at the present time, we do not believe that it is clinically useful for detection of P. carinii in BALF samples. P. carinii DNA amplification by PCR should be reserved for testing IF-negative BALF samples from patients judged clinically to have PCP.
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The Effects of RU 41. 740, a Glycoprotein Immunomodulating Agent Derived from Klebsiella Pneumoniae, on Intra-Abdominal Abscess Formation in Mice
SummaryThe prophylactic and therapeutic efficacies of the immunomodulating agent RU 41. 740 (a glycoprotein extract from Klebsiella pneumoniae) were studied in a murine model of intra-abdominal abscess formation with Bacteroides fragilis, Escherichia coli, and bran as an abscess-potentiating agent. Parenteral injection of RU 41. 740, either before or after injection of an abscess-inducing mixture (AIM), was associated with significantly diminished incidence and size of abscesses. Abscess incidence and size were significantly decreased by oral administration of RU 41. 740 after, but not before, AIM injection. Abscess formation and resolution are the results of complex interactions of host defence mechanisms with bacteria and potentiating agent, and RU 41. 740 has been shown previously to activate both macrophage and neutrophil function. These results indicate that activation of non-specific defences may protect against abscess development in chronic sepsis.
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