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The aim of the present study was to evaluate the effect of natural deproteinized bone mineral on the temporal and spatial pattern of bone formation in a guided bone regeneration model system while using a bioresorbable membrane device. A periosteal skin flap was raised uncovering the calvaria of 20 rabbits. A stiff hemispherical dome made of polylactic acid was placed onto the roughened calvaria and anchored by screws. Prior to placement, the dome was either filled with peripheral blood (control group, 8 rabbits) or with blood and OsteoGraf/N-300 (test group, 12 rabbits). At 1 month, histologic sections revealed bone regeneration in both test and control domes to various degrees. In the test domes, bone height reached 78% (67-83) and bone volume was 11% (6-17), while in the control domes, bone height was 45% (14-67) and bone volume 6% (1-11). At 2 months, bone height was unchanged in the test group at 70% (67-83) and bone volume had only slightly increased to 16% (11-21). In the controls, height increased to 86% (60-100) and volume to 20% (9-27). Thus, in this model system, natural bone mineral fill contributed to accelerate initial bone neogenesis, while it did not contribute to increasing bone volume or bone height at later observation stages.

Warburg showed in 1929 that the photochemical action spectrum for CO dissociation from cytochrome c oxidase is that of a heme protein. Keilin had shown that cytochrome a does not react with oxygen, so he did not accept Warburg's view until 1939, when he discovered cytochrome a3. The dinuclear cytochrome a3-CuB unit was found by EPR in 1967, whereas the dinuclear nature of the CuA site was not universally accepted until oxidase crystal structures were published in 1995. There are negative redox interactions between cytochrome a and the other redox sites in the oxidase, so that the reduction potential of a particular site depends on the redox states of the other sites. Calculated electron-tunneling pathways for internal electron transfer in the oxidase indicate that the coupling-limited rates are 9 x 10(5) (CuA--a) and 7 x 10(6) s(-1) (a--a3); these calculations are in reasonable agreement with experimental rates, after corrections are made for driving force and reorganization energy. The best CuA-a pathway starts from the ligand His204 and not from the bridging sulfur of Cys196, and an efficient a-a3 path involves the heme ligands His378 and His376 as well as the intervening Phe377 residue. All direct paths from CuA to a3 are poor, indicating that direct CuA--a3 electron transfer is much slower than the CuA--a reaction. The pathways model suggests a means for gating the electron flow in redox-linked proton pumps.

The aim of this study was to evaluate the effect of deproteinized bovine bone graft material on new bone formation in a guided bone regeneration model system. In 20 rabbits, a periosteal skin flap was raised uncovering the calvaria. A form stable hemispherical dome made of poly-lactic acid (PLA) was placed onto the roughened calvaria. Prior to placement, the dome was either filled with peripheral blood alone (control group, 8 rabbits), or with blood and OsteoGraf/N-300 (test group, 12 rabbits). The wound was closed for primary healing. Morphometric assessment of 1- and 2-month undecalcified histologic specimens revealed better tissue fill in the test domes at 1 month (test 99%, control 55%) (P0.05) and 2 months (t, 100%; c, 82%). The fraction of the new bone within the regenerated tissue was higher in the test specimens at 1 month (t, 22%; c, 12%) (P0.05) and 2 months (t, 34%; c, 24%). The fraction of the entire space underneath the domes occupied by bone was higher in the test at 1 month, but higher in the controls at 2 months. The fraction of the bone substitute material in contact with bone increased from 1 month (34% +/- 14) to 2 months (45% +/- 5). The surface fraction of osteoblast layers was tendentially higher in the test at 1 month but higher in the control specimens at 2 months. In both test and control, initially woven bone was formed which underwent subsequent remodeling. Cellular degradation of the deproteinized bone graft was frequently detected. It is concluded that deproteinized bovine bone mineral has osteoconductive properties and can initially accelerate new bone formation during guided bone regeneration by increased recruitment of osteoblasts.

The aim of the present study was to evaluate the effect of natural deproteinized bone mineral on the temporal and spatial pattern of bone formation in a guided bone regeneration model system while using a bioresorbable membrane device. A periosteal skin flap was raised uncovering the calvaria of 20 rabbits. A stiff hemispherical dome made of polylactic acid was placed onto the roughened calvaria and anchored by screws. Prior to placement, the dome was either filled with peripheral blood (control group, 8 rabbits) or with blood and OsteoGraf/N-300 (test group, 12 rabbits). At 1 month, histologic sections revealed bone regeneration in both test and control domes to various degrees. In the test domes, bone height reached 78% (67-83) and bone volume was 11% (6-17), while in the control domes, bone height was 45% (14-67) and bone volume 6% (1-11). At 2 months, bone height was unchanged in the test group at 70% (67-83) and bone volume had only slightly increased to 16% (11-21). In the controls, height increased to 86% (60-100) and volume to 20% (9-27). Thus, in this model system, natural bone mineral fill contributed to accelerate initial bone neogenesis, while it did not contribute to increasing bone volume or bone height at later observation stages.

Whole-cell affinity chromatography was used as a novel screening technique for identifying and characterizing oral microbial lectins. First, affinity columns bearing oligosaccharides of defined structure were synthesized as lectin-binding reagents. Fetuin, transferrin (containing terminal NeuAc residues), asialofetuin and asialotransferrin (with terminal Gal residues) were covalently coupled to Sepharose 6MB and incubated with 3H-labeled bacterial suspensions in columns fitted with an 80-μm nylon filter. Bacteria specifically bound were then eluted with the appropriate sugar (NeuAc or Gal). Fusobacterium nucleatum was the most significant binder, with 80% specifically eluted from the asialo-derivatives. Actinomyces viscosus and Actinomyces naeslundii also showed unique specificity for galactose. In contrast, Streptococcus sanguis bound in greatest numbers to fetuin, consistent with the presence of a sialic acid-binding site on these bacteria.