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Biomedical subjects

R Claesson

Publications and source records attributed to R Claesson.

26 records · Page 2Linked to original sources
PubMed1990

Production of volatile sulfur compounds by various Fusobacterium species.

In 12 species of Fusobacterium the following characteristics were studied; the desulfhydration of L-cysteine and L-methionine by resting cell suspensions, the formation of alpha-keto-acids from L-cysteine, D-cysteine and L-methionine by cell extracts, and the formation of hydrogen sulfide from L-cysteine, D-cysteine and L-cysteine by cell extracts separated by polyacrylamide gel electrophoresis. Multiple forms of L-cysteine desulfhydrase activity were found in most of the species. In some of them also D-cysteine desulfhydrase activity was demonstrated. Seven of the species had high L-methionine gamma-lyase activity. L-cysteine activity was present in 5 of the species.

Carbon-Sulfur Lyases↗
PubMed1990

The formation of hydrogen sulfide and methyl mercaptan by oral bacteria.

The capacity to form volatile sulfur compounds was tested in bacteria isolated from subgingival microbiotas and in a representative number of reference strains. A majority of the 75 tested oral bacterial species and 7 unnamed bacterial taxa formed significant amounts of hydrogen sulfide from L-cysteine. The most active bacteria were found in the genera Peptostreptococcus, Eubacterium, Selenomonas, Centipeda, Bacteroides and Fusobacterium. Methyl mercaptan from L-methionine was formed by some members of the genera Fusobacterium, Bacteroides, Porphyromonas and Eubacterium. When incubated in serum for 7 d, the most potent producers of hydrogen sulfide were Treponema denticola and the black-pigmented species, Bacteroides intermedius, Bacteroides loescheii, Porphyromonas endodontalis and Porphyromonas gingivalis. P. endodontalis and P. gingivalis also produced significant amounts of methyl mercaptan in serum. No other volatile sulfur compound was detected in serum or in the presence of L-cysteine and L-methionine. These findings significantly increase the list of oral bacteria known to produce volatile sulfur compounds.

Bacteroides↗
PubMed1989

The capacity of subgingival microbiotas to produce volatile sulfur compounds in human serum.

Hydrogen sulfide is formed by the subgingival microbiotas of periodontal pockets. The capacity of these microbiotas to form various volatile sulfur compounds in human serum was studied. Bacterial samples from nine deep periodontal pockets were incubated for 7 days in human serum and the amounts of volatile sulfur compounds and the degradation of serum proteins were determined. Hydrogen sulfide was the predominant volatile sulfur compound, but also methyl mercaptan was formed in significant amounts. Only traces of dimethyl sulfide and dimethyl disulfide were detected. There was an extensive degradation of the serum proteins. In most of the reaction mixtures hydrogen sulfide reached highly toxic levels.

Bacteria↗
PubMed1989

Presence of mutans streptococci and various types of lactobacilli in interdental spaces related to development of proximal carious lesions.

During a 2-yr study period samples from saliva, the tongue, and 276 interdental spaces were obtained from 23 7-yr-old children in order to (a) relate the presence of lactobacilli in various oral sites to the occurrence of lactobacilli in saliva, and (b) relate the presence of mutans streptococci and various types of lactobacilli interdentally to the development of proximal carious lesions. The results showed an increased number of interdental samples containing lactobacilli with an increasing number of salivary lactobacilli. Furthermore, lactobacilli were never found interdentally without the presence of mutans streptocci, lactobacilli proved to be the more suitable microorganism for prediction of proximal carious lesions. Neither the number nor the differentiation into different species of interdental lactobacilli seemed to be of importance, but simply whether they were present. The presence of lactobacilli probably reflects a caries-inducing environment (etiologic microflora + fermentable carbohydrates), thus explaining their high predictive ability compared to their rather limited etiologic importance in the initiation of decay.

Child↗
PubMed1989

Activity of polymorphonuclear leukocytes in the presence of sulfide.

Polymorphonuclear leukocytes (PMN) isolated from human blood were exposed to various levels of hydrogen sulfide. The effect on respiratory burst, myeloperoxidase activity, and capacity to phagocytose and kill bacteria were studied. A 1-h exposure of the PMN to 1 mM sulfide did not decrease their myeloperoxidase activity or their capacity to initiate a respiratory burst. Actually the products of the respiratory burst rapidly oxidized sulfide. The phagocytosis and killing of bacteria in the presence of 1 mM sulfide was only decreased to a minor extent. Myeloperoxidase in cell extract was, however, almost completely inhibited by 1 microM sulfide. These results indicate that hydrogen sulfide does not easily permeate PMN. PMN may be able to function in infected sites with high sulfide levels such as in the gingival pockets of periodontal disease. In the oxygenated areas of these sites the PMN may actually help in the detoxification of sulfide.

Blood Bactericidal Activity↗
PubMed1988

Catalase inhibition by sulfide and hydrogen peroxide-induced mutagenicity in Salmonella typhimurium strain TA102.

The lethal and mutagenic effects of hydrogen peroxide were studied in exponentially growing cultures of Salmonella typhimurium strain TA102. Exposure of the cultures to non-lethal levels of sodium sulfide significantly increased the lethality and mutagenicity of hydrogen peroxide. The catalase activity was decreased in cells exposed to sodium sulfide, but there were no changes in the cellular levels of superoxide dismutase, glutathione reductase, or NADPH-dependent alkyl hydroperoxide reductase. Hydrogen peroxide-induced mutagenesis and killing of S. typhimurium strain TA102 in the presence of sulfide may in part be explained by an inactivation of catalase by sulfide.

Catalase↗
PubMed1985

Presence of Lactobacillus casei in saliva from children and adults using a new medium.

The aim of this study was to devise a medium for cultivation of L. casei and to compare the presence of L. casei in saliva from children and adults. The new medium was produced by omitting the sugars from Rogosa SL agar medium and supplementing this medium with melezitose. Although all tested strains of lactobacilli grew on the new medium, the facultatively homofermentative lactobacilli, L. casei and L. plantarum, could be identified by a typical colonial morphology. L. casei was the most common species of oral lactobacilli in saliva from children and made up a significantly higher proportion of the salivary lactobacillus flora in children than in adults.

Adolescent↗