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Biomedical subjects

D Lundgren

Publications and source records attributed to D Lundgren.

At least 73 records · Page 4Linked to original sources
PubMed1978

Sulfide oxidation by spheroplasts of Thiobacillus ferrooxidans.

Thiobacillus ferrooxidans is an acidophilic organism important to metal leaching of low-grade ores. The aforementioned importance is related to the ability of the bacterium to oxidize reduced iron and sulfur, principally found in nature as pyrite (FeS2). The present study dealt with sulfide oxidation at low pH values and the involvement of the cell envelope in the process of the inorganic oxidations. Sulfide oxidation was noted in spheroplasts of T. ferrooxidans prepared by enzymatic and chemical treatments and partially purified by differential centrifugation. No enzyme activities were noted in membrane fractions containing enrichments of lipopolysaccharide symbolic of outer membrane material or in membrane vesicles containing (or associated with) higher levels of proteins. Results to date indicate that in an acid milieu the envelope structure containing both the outer membrane and the intact inner cytoplasmic membrane is required for sulfide oxidation.

Cell Membrane↗
PubMed1975

Functional analysis of fixed bridges on abutment teeth with reduced periodontal support.

The present study examines the function of fixed bridges on abutment teeth with reduced but non-inflamed periodontal tissues. Eighteen patients with advanced periodontal breakdown and indication for oral rehabilitation received periodontol treatment and their dentitions were restored with fixed bridgework. The analysis of function performed 2-5 years after insertion of the reconstructions was made by (1) evaluation of the patients' opinion on chewing ability and function of the masticatory system; (2) clinical examination of the border movements of the mandible, the status of the temporomandivular joints and the chewing muscles, and (3) measurements of the bite force indifferent areas of the dentition. The results of the study show that the functional capacity of the type of extensive bridgework discussed is good and that the patients--in spite of severe loss of periodontal tissue--achieve bite force values that are almost comparable to those in individuals with natural teeth. Comparison of the function of fixed bridges and that of removable dentures is also discussed.

Adult↗
PubMed1975

The role of occlusion for the stability of fixed bridges in patients with reduced periodontal tissue support.

The present investigation reports how occlusion may be utilized to establish and maintain stability of fixed bridges in patients with markedly reduced periodontal tissue support. The material consisted of 20 adult patients, aged 27-69, with advanced periodontal breakdown, often in combination with extensive loss of teeth. After periodontal treatment, the patients were rehabilitated with fixed bridges, whose stability was evaluated once a year for 2 to 6 years. The results show that permanent stability of bridgework can be obtained in patients where there is a minimum of remaining periodontal tissue support, even in combination with marked hypermobility of individual abutment teeth. The stability was achieved by proper treatment of the diseased periodontal tissues, and by establishment of stable occlusion in the intercuspal position. When there was a risk of bridge mobility on excursive movements of the mandible, balancing contacts were established for the prevention of migration, tilting and increasing mobility. The study also shows that cantilever pontics can be used to achieve and maintain the stability of fixed bridgework.

Adult↗