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SUMMARYTreponema denticola is associated with subgingival biofilms in adult periodontitis and with acute necrotizing ulcerative gingivitis. However, the molecular mechanisms by which T. denticola impacts periodontal inflammation and alveolar bone resorption remain unclear. Here, we examined changes in the host transcriptional profiles during a T. denticola infection using a murine calvarial model of inflammation and bone resorption. T. denticola was injected into the subcutaneous soft tissue over the calvaria of BALB/c mice for 3 days, after which the soft tissues and the calvarial bones were excised. RNA was isolated and analysed for transcript profiling using Murine GeneChip® arrays. Following T. denticola infection, 2905 and 1234 genes in the infected calvarial bones and soft tissues, respectively, were differentially expressed (p ≤ 0.05). Biological pathways significantly impacted by T. denticola infection in calvarial bone and calvarial tissue included leukocyte transendothelial migration, cell adhesion (immune system) molecules, cell cycle, extracellular matrix-receptor interaction, focal adhesion, B-cell receptor signaling and transforming growth factor-β signaling pathways resulting in proinflammatory, chemotactic effects, and T-cell stimulation. In conclusion, localized T. denticola infection differentially induces transcription of a broad array of host genes, the profiles of which differed between inflamed calvarial bone and soft tissues.

The introduction of targeted cancer therapies into clinical practice, in which patients are selected for novel treatments based on results of companion molecular testing of their tumor specimens, has created significant new challenges for the surgical pathology laboratory. These include standardization of tissue handling and sample preparation with accurate documentation to ensure optimal quality of clinical samples to reduce the risk of errors in molecular biology tests. The assay of tumor tissues for biomarkers that can provide predictive data for prognosis or treatment should enable selection of the most appropriate therapies (Yaziji et al. 2008, Hicks and Kulkarni 2008). Major advances have been made in the ability to profile clinical samples for research at the DNA, RNA and protein levels. To translate this new information into the clinical setting, however, the quality of the starting material, in this case the tumor tissue, determines the accuracy and reliability of companion diagnostic assay results and therefore optimal therapeutic strategies. Inaccurate results owing to compromised tissue quality can lead to false positive or false negative results with therapeutic consequences that can harm patients and affect their eventual outcome.

Pathologists have used light microscopes and glass slides to interpret the histologic appearance of normal and diseased tissues for more than 150 years. The quality of both microtomes used to cut tissue sections and microscopes has improved significantly during the past few decades, but the process of rendering diagnoses has changed little. By contrast, major advances in digital technology have occurred since the introduction of hand held electronic devices, including the development of whole slide imaging (WSI) systems with software packages that can convert microscope images into virtual (digital) slides that can be viewed on computer monitors and via the internet. To date, however, these technological developments have had minimal impact on the way pathologists perform their daily work, with the exception of using computers to access electronic medical records and scholarly web sites for pertinent information to assist interpretation of cases. Traditional practice is likely to change significantly during the next decade, especially since the Federal Drug Administration in the USA has approved the first WSI system for routine diagnostic practice. I review here the development and slow acceptance of WSI by pathology departments. I focus on recent advances in validation of WSI systems that is required for routine diagnostic reporting of pathology cases using this technology.

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SUMMARY Tannerella forsythia is associated with subgingival biofilms in adult periodontitis, although the molecular mechanisms contributing to chronic inflammation and loss of periodontal bone remain unclear. We examined changes in the host transcriptional profiles during a T. forsythia infection using a murine calvarial model of inflammation and bone resorption. Tannerella forsythia was injected into the subcutaneous soft tissue over calvariae of BALB/c mice for 3 days, after which, the soft tissues and calvarial bones were excised. RNA was isolated and Murine GeneChip® array analysis of transcript profiles showed that 3226 genes were differentially expressed in the infected soft tissues (P < 0.05) and 2586 genes were differentially transcribed in calvarial bones after infection. Quantitative real-time reverse transcription-polymerase chain reaction analysis of transcription levels of selected genes corresponded well with the microarray results. Biological pathways significantly impacted by T. forsythia infection in calvarial bone and soft tissue included leukocyte transendothelial migration, cell adhesion molecules (immune system), extracellular matrix–receptor interaction, adherens junction, and antigen processing and presentation. Histologic examination revealed intense inflammation and increased osteoclasts in calvarias compared with controls. In conclusion, localized T. forsythia infection differentially induces transcription of a broad array of host genes, and the profiles differ between inflamed soft tissues and calvarial bone.

Complete calcification of osteoid could account for the presence of aluminium lines within fully calcified bone. The Aluminon stain appears to be a more sensitive method for the detection of aluminium in bone than electronprobe Xray microanalysis.Aluminium can be detected at the interface between osteoid and calcified matrix (the mineralisation front) in bone from some patients with chronic renal failure'" after exposure to high levels of aluminium in the dialysis water78 or following treatment with aluminiumcontaining phosphate-binding drugs.39 10 At this site it appears to interfere with mineralisation and thereby cause osteomalacia, although its precise mechanism of toxic action remains obscure. In many biopsy specimens from patients with aluminium-related osteomalacia, however, one or more aluminium lines can also be seen within the calcified bone matrix.2356 Thus, despite the presence of aluminium at the mineralisation front, thickened osteoid seams appear to be able to calcify, although the mechanism whereby this calcification takes place remains unexplained.On review of our bone biopsy specimens from patients with aluminium-related osteomalacia we noted that many had irregularly shaped areas of patchy mineralisation within the thickened osteoid seams as well as aluminium lines within the fully mineralised bone. This form of mineralisation differs from normal mineralisation in that the latter takes place linearly along the interface between osteoid and calcified bone, the mineralisation front. This front can be seen as a thin line with toluidine blue staining or following tetracycline labelling. We studied the patchy mineralisation in detail using light and electron microscopy.The results are described of our histomorphometric, ultrastructural, and X-ray microanalytical study of the patchy mineralisation in bone biopsy specimens from five patients with aluminium-related osteomalacia. On the basis of the light microscopic and ultrastructural findings we propose a mechanism to explain the presence of aluminium lines within calcified bone that is related to healing of the mineralisation defect. MethodsWe reviewed sections from 55 undecalcified bone biopsy specimens taken over a five year period from 35 renal dialysis patients with biopsy proven aluminium-related osteomalacia (increased extent and thickness of osteoid seams and positive aluminium staining along the interface between the osteoid and the fully calcified bone, the mineralisation front). In 38 of the specimens we observed irregularly shaped areas of patchy mineralisation within the thickened osteoid seams in sections stained