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  • 1
    Electronic Resource
    Electronic Resource
    Decay rates of exocellular enzymes produced by bacteria-correction of production rates in chemostat cultures (1979)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 6 (1979), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1979.tb03734.x
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  • 2
    Electronic Resource
    Electronic Resource
    Cytotoxic activity of Propionibacterium acnes and other skin organisms (1985)
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 113 (1985), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Culture supernatants from four species of skin micro-organisms were tested against VERO (monkey kidney cells) and skin fibroblasts for cytotoxic activity. Cytotoxic activity was produced by the three species of Propionibacterium tested (P. acnes, P. avidum and P. granulosum), and this activity was highest when cultures were grown in the presence of glucose. In contrast, Staphylococcus epidermidis was devoid of cytotoxic activity whether grown in the presence of glucose or not.The agent responsible for the cytotoxic activity was heat stable, of low molecular weight and removable from supernatants by ether extraction. These properties, coupled with the finding that the levels of cytotoxicity are directly proportional to the concentrations of propionate measured in samples, suggests that propionate is the agent responsible for the cytotoxicity of the culture supernatants. Pure propionate and the salts of other carboxylic acids (C1 to C5) were tested at the same concentrations and showed different degrees of cytotoxicity depending on their chain length.Propionate may have an important role in the aetiology of the disease acne vulgaris.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2133.1985.tb02069.x
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  • 3
    Electronic Resource
    Electronic Resource
    Cytotoxic effects of antimicrobial photodynamic therapy on keratinocytes in vitro (2002)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 146 (2002), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary Background Previous work has shown that cutaneous microbial species associated with skin conditions of microbial aetiology are susceptible to killing by photodynamic therapy (PDT) using visible light and methylene blue. Antimicrobial PDT (APDT) in vivo would require a therapeutic regimen where bacteria could be killed without damaging adjacent tissue. Objectives To study keratinocyte killing in vitro using APDT. Methods We used a combination of methylene blue (100 μg mL−1) and visible light␣(42 mW cm−2), previously used for microbial killing, to study cytotoxic effects on keratinocytes. Kill rates and subsequent D-values were determined against a human keratinocyte cell line (H103) using trypan blue and neutral red dye viability tests. Results The kill rates for keratinocytes were exponential over the 90- and 180-min period of the experiment for neutral red and trypan blue, respectively. The corresponding D-values were shown to be 198 and 205 min using trypan blue exclusion and neutral red uptake viability tests, respectively. Conclusions The kill rates for keratinocytes were 18–200-fold slower than those previously determined for cutaneous microbial species, suggesting that in vivo, APDT sufficient to reduce microbes by seven log cycles would have little cytotoxic effect on keratinocytes. This approach may offer a safe alternative to conventional antimicrobial treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.2002.04623.x
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  • 4
    Electronic Resource
    Electronic Resource
    Antimicrobial photodynamic therapy: assessment of genotoxic effects on keratinocytes in vitro (2003)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 148 (2003), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary Background Work has shown that cutaneous microbial species associated with skin conditions of microbial aetiology are susceptible to killing by antimicrobial photodynamic therapy (APDT) using visible light and methylene blue. Objectives To evaluate immediate and delayed genotoxicity of APDT on keratinocytes in vitro. Methods A combination of methylene blue (100 µg mL−1) and visible light (42 mW cm−2), as used in studies of microbe and keratinocyte cytotoxicity, was employed to test a human keratinocyte cell line (H103) for genotoxic damage by comet assay. Results The comet assay was able to detect genotoxic damage in H2O2-treated keratinocytes (positive control). APDT did not cause either immediate or delayed genotoxic damage in keratinocytes following APDT of up to 180 min. Conclusions APDT sufficient to reduce microbes by seven log cycles showed no detectable genotoxic effects on keratinocytes. APDT applied in vivo may represent a useful low-risk alternative to conventional antimicrobial treatment in dermatology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.2003.05091.x
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  • 5
    Electronic Resource
    Electronic Resource
    The production of inflammatory compounds by Propionibacterium acnes and other skin organisms (1987)
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 117 (1987), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Culture supernatants from four species of skin microorganisms (P. acnes, P. avidum, P. granulosum and S. epidermidis) were assayed for smooth muscle contracting substances which are indicative of inflammatory activity. At least three types of smooth muscle contracting substances were detected. These were: first, a substance active on a rat fundic strip preparation and antagonized by N, N-DMT. Activity was enhanced when cultures were grown in the presence of tryptophan. This substance was probably tryptamine. Second, a substance active on a guinea-pig ileum preparation and antagonized by mepyramine. Activity was enhanced when cultures were grown in the presence of histidine. This substance was probably histamine. Third, a substance active on a rat fundic strip preparation but not antagonized by N, N-DMT, epyramine, atropine or indomethacin. Activity was enhanced when cultures were grown in the presence of glucose. This activity was probably due to acetate, propionate or other short-chain fatty-acid salts.Chromatographic analysis confirmed the presence of histamine, tryptamine and short-chain fatty acids in the culture supernatants. These substances if produced in vivo may cause or contribute to inflammation and pain directly without the prior mediation of the immune system.Cell extracts of Propionibacterium species were analysed by bioassay for the presence of prostaglandin-like compounds. These could not be detected in any of the eight strains of organisms tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2133.1987.tb04114.x
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  • 6
    Electronic Resource
    Electronic Resource
    Killing of cutaneous microbial species by photodynamic therapy (2001)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 144 (2001), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Photodynamic therapy (PDT) utilizes photosensitizers and light. Whereas PDT use in cancer treatment has been widely accepted, antimicrobial PDT (APDT) is still in its early stages of development. Objectives To study microbial killing in vitro using APDT. Methods We used a combination of methylene blue and visible light, and a range of microbial species representative of those encountered on the skin in health and disease. Using standard light intensity conditions (slide projector, 25 cm distance from target, 42 mW cm−2) and methylene blue dye at 100 µg mL−1, kill rates and subsequent D-values were determined against Staphylococcus aureus, S. epidermidis, Streptococcus pyogenes, Corynebacterium minutissimum, Propionibacterium acnes and Candida albicans. Results D-values for these species were 72, 66, 48, 120, 30 and 660 s, respectively. The effects of light intensity on the killing of S. epidermidis showed the kill rate to be proportional to the light intensity. A high rate of cell kill was also obtained using natural sunlight. Conclusions Overall, these results indicate that APDT of the skin may represent a useful alternative to conventional antimicrobial treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.2001.04013.x
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  • 7
    Electronic Resource
    Electronic Resource
    Detection and possible biological role of chondroitinase and heparitinase enzymes produced by Porphyromonas gingivalis W50 (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 32 (1997), S. 0 
    Details
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Gingival crevicular fluid levels of the glycosaminoglycan (GAG) chondroitin-4-sulphate (C-4-S) have received increased attention as potential indicators of periodontal tissue turnover. However, little is known about the relationship between crevicular fluid connective tissue metabolites and microbial factors. In this study Porphyromonas gingivalis, a periodontopathogen, was investigated for its ability to degrade the GAGs C-4-S, dermatan sulphate (DS) and heparan sulphate (HS) in vitro. The effect of P. gingivalis extracts on the proteoglycans (PG) derived from human gingiva were also investigated. The presence of chondroitinase and heparitinase eliminase enzymes were identified from the vesicle fraction of P. gingivalis W50. These enzymes were extracted from the vesicle fraction by a differential centrifugation technique and partially purified by non-denaturing gel filtration chromatography which revealed heparitinase enzyme peaks at 200 and 150 kDa and chondroitinase at 70 kDa. Gingival proteoglycans for use as substrates were purified using 4 M guanidinium chloride extraction and anion exchange chromatography; these proteoglycans contained 48% DS, 27% C-4-S and 13% HS P. gingivalis chondroitinase and heparitinase enzymes were capable of the degradation of C-4-S and HS but not DS GAGs. The presence of chondroitinase enzymes produced by P. gingivalis may influence levels of connective tissue metabolites in crevicular fluid. Furthermore these enzymes, particularly the heparitinase, may be involved in the initial permeation of the gingival epithelium, permitting the ingress of further microbial virulence factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0765.1997.tb01376.x
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  • 8
    Electronic Resource
    Electronic Resource
    Serum antibodies against the trypsin-like protease of Bacteroides gingivalis in periodontitis (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 23 (1988), S. 0 
    Details
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Antibody levels of IgG, IgA and IgM reactive to the trypsin-like enzyme of B. gingivalis were measured by enzyme-linked immunosorbent assay in serum samples from control subjects with clinically healthy gingiva, patients with adult periodontitis (AP) and patients with rapidly progressive periodontitis (RPP). Both AP and RPP patients had significantly higher levels of specific IgG and IgA antibodies than control subjects with healthy gingiva (p〈0.001 in both cases). No significant difference was observed between the specific IgM antibody activity in the AP group compared to the control group. However, a significant difference was seen (p〈0.01) for IgM activity in the RPP group compared to controls. The results indicate that the trypsin-like enzyme of B. gingivalis is produced in vivo in sufficient amounts to be immunogenic to the host and particularly in patients with AP or RPP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0765.1988.tb01357.x
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  • 9
    Electronic Resource
    Electronic Resource
    Hölder-Banach space analysis of the Bethe-Salpeter equation (1970)
    Springer
    Communications in mathematical physics 16 (1970), S. 123-135 
    Details
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We find a Hölder Banach space in which the Bethe-Salpeter equation is a compact integral equation as it stands. We study the properties of the solution in preparation for an analysis of linear field theory models of 3-body amplitudes. In particular we study the properties of the Regge poles of the solution and prove the existence and uniqueness of on mass shell scattering amplitudes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01646617
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