Lipopolysaccharide-stimulated osteoclastogenesis is mediated by tumor necrosis factor via its P55 receptor

Chronic bone infection, as attends periodontitis, is often complicated by severe osteolysis. While LPS is believed to be central to the pathogenesis of the osteolytic lesion, the mechanisms by which this bacteria-derived molecule promotes bone resorption are unknown. We find that LPS induces bone marrow macrophages (BMMs) to express c-src, a protooncogene product that we demonstrate is a specific marker of commitment to the osteoclast phenotype. We next turned to possible soluble mediators of LPS-induced c-src. Of a number of osteoclastogenic cytokines tested, only TNF-alpha mirrors the c-src-enhancing effect of LPS. Suggesting that LPS augmentation of c-src is TNF-mediated, endotoxin sequentially induces BMM expression of TNF, followed by c-src. TNF and c-src expression, by cultured BMMs derived from LPS-injected mice, reflects duration of exposure to circulating endotoxin, intimating that endotoxin's effect in vivo is also mediated by TNF. Consistent with these findings, thalidomide (which antagonizes TNF action) attenuates c-src induction by LPS. An anti-TNF antibody blocks LPS enhancement of c-src mRNA, validating the cytokine's modulating role in vitro. Using BMMs of TNF receptor-deleted mice, we demonstrate that TNF induction of c-src is transmitted through the cytokine's p55, but not p75, receptor. Most importantly, LPS administered to wild-type mice prompts osteoclast precursor differentiation, manifest by profound osteoclastogenesis in marrow cultured ex vivo, and by a profusion of marrow-residing cells expressing the osteoclast marker tartrate resistant acid phosphatase, in vivo. In contrast, LPS does not substantially enhance osteoclast proliferation in mice lacking the p55TNF receptor, confirming that LPS-induced osteoclastogenesis is mediated by TNF in vivo via this receptor. Thus, therapy targeting TNF and/or its p55 receptor presents itself as a means of preventing the osteolysis of chronic bacterial infection.     

Contribution of IL-1 beta to the enhancement of Campylobacter rectus lipopolysaccharide-stimulated PGE2 production in old gingival fibroblasts in vitro

Campylobacter rectus is associated with adult periodontitis. We previously reported that C. rectus lipopolysaccharide (LPS)-stimulated prostaglandin E2 (PGE2) production in old cells of human gingival fibroblasts (HGFs) is higher than that in young cells. The present study examined whether an enhancement of C. rectus LPS-stimulated interleukin (IL)-1 beta production in old HGFs contributed to the increased production of PGE2. LPS was prepared from C. rectus ATCC33238. HGFs were established from healthy gingiva in three patients, aged 10-12 years. Cellular aging in culture was determined with increasing doubling. The cultured cells were treated with LPS (0.01-10 micrograms/ml), and the amount of IL-1 beta in the medium was measured after a 24 h incubation. The LPS-stimulated IL-1 beta production in each old cell (corresponding to 57-67% of complete life-span) was increased (1.6-2.6 times) compared to that in the young cells (corresponding to 17-20% of the life-span). The IL-1 beta mRNA synthesis in the presence of LPS in the old cells was higher than that in the young cells. The enhancement of LPS-stimulated PGE2 production was inhibited by anti-IL-1 beta antibody and by IL-1 receptor antagonist. These findings suggest that the greater ability of old cells to produce PGE2 in response to C. rectus LPS is due to their greater level of IL-1 beta.     

A Dual-Tone Multifrequency Receiver Using Synchronous Additions and Subtractions

This paper describes a new detection algorithm for a dualtone multifrequency (DTMF) signal. The new algorithm basically uses only additions and subtractions but no multiplications. A signaling tone can be detected by sampling an input signal at four times each frequency involved in a signaling tone and accumulating these sampled values synchronously by additions and subtractions. This algorithm is referred to as the synchronous additions and subtractions (SAS) method. Many conventional methods have used various types of filters to detect signaling tones. In the SAS method in which the design of filters is unnecessary, only the generation of sampling pulses is required, and main operations are additions and subtractions. These features are useful to implement flexible receivers and various types of receivers. The simplicity of the SAS method is demonstrated by the implementation of a DTMF receiver using a conventional 8-bit microcomputer without any special hardware. The minimum signal-to-noise ratio is 5.7 dB when the receiver operates for the signaling tones to be accepted. Four easily measurable parameters are used to distinguish signaling tones from noise inputs. Only two false detections occurred for severe noise inputs of thirty hours.     

Efficient photodiode-waveguide coupling for hybrid integrated optical circuits

A GalnAsP edge-detecting photodiode was coupled with an SiO2-TiO2 single-mode waveguide in a simple hybrid integration scheme. The newly developed edge-detecting photodiode with a window region was used to improve photodiode durability.     

Recrystallisation of amorphous natural brannerite through annealing: The effect of radiation damage on the chemical durability of brannerite

An amorphous natural brannerite sample was chosen to study the annealing of the radiation damage through thermal recrystallisation, and subsequently to evaluate the effect of radiation damage on its aqueous durability. Microstructural characterisation of the natural brannerite revealed minor alteration along the rim of the crystal and within cracks. The formation of UO₂ particles and soluble Pb–Ca-rich aluminosilicate glass is responsible for the higher U and Pb releases from the recrystallised brannerite. In general, natural brannerite has been shown to be resistant to dissolution over geological time, therefore minor brannerite inclusions in ceramic formulations for immobilisation of actinide-rich radioactive wastes should not have a detrimental effect on the long-term chemical durability of the wasteforms.     

Spray deposition process study of SnO2silicon solar cells using orthogonal experimental design

With the “orthogonal experimental design” (OED), the dependence of conductivity and transparency of tin oxide films and open circuit voltage V_oc of SIS solar cells on the spray deposition process factors was studied. The OED technique was found to be a powerful method for realizing the best factor combination. Using OED, curves were obtained which clearly depict the effects of each factor on the SIS characteristics. The results of the experiments also illustrate exactly which variation in fabrication technique most affects the sheet resistance, V_oc, and film transparency. Under the optimal combination of conditions, a thin film doped with NH₄F was obtained, with about 90% transmission and a sheet resistance of about 80 Ω/□, along with an SIS structure with a V_oc of about 0.61 V.     

Polarization-controlled single-mode VCSEL

Relative intensity noise (RIN) in a vertical-cavity surface-emitting laser (VCSEL) was greatly reduced through the use of polarization control to eliminate competition between two orthogonal polarization states by ensuring there was only one polarization state. Polarization was stable with optical feedback of up to 10%. Polarization control was achieved by inducing a small loss anisotropy in fundamental transversal mode VCSEL's. Anisotropic post structures, such as a rectangular post, an oblique post, or a zigzag-sidewall post, were found to be effective in creating loss anisotropy without serious degradation of other VCSEL characteristics such as light-output power or beam profile