Lars Frithiof

A highly ordered structure in keratinizing human oral epithelium

In some cell layers of keratinizing oral epithelium, normal as well as pathological, small lamellated bodies are demonstrated. The fine structure of these bodies closely resembles that of synthetic phospholipid preparations studied by electron optical methods. This structural similarity is assumed to be due to a chemical relationship. In the superficial layer of the stratum granulosum lamellated material is found in the intercellular space and can be seen also between cells in the basal part of the stratum corneum. In the central and superficial parts of the stratum corneum, intercellular material occurs only as homogeneous, dense bodies. Lamellated material has not been observed inside the keratinized cells.

Proximal alveolar bone loss in a longitudinal radiographic investigation: IV. Smoking and some other factors influencing the progress in individuals with at least 20 remaining teeth

In Sweden people in all age groups now have more remaining teeth than previously. An investigation has been made to identify some predictors of alveolar bone loss in a 10-year period in subjects with at least 20 remaining teeth. The material consisted of 349 individuals, examined radiographically, clinically, and by interview in 1970 and in 1980. These subjects, born in 1904-1952, constituted a subgroup, with regard to remaining teeth, of an unselected sample of the population of the old county of Stockholm. In the unselected sample statistically significant predictors of alveolar bone loss found in a stepwise multiple regression analysis were alveolar bone loss in 1970, age, number of lost teeth, and Russells Periodontal Index (PI). In the subgroup the predictors were in the order Russells PI and smoking. The prediction values (R2) of further variables were marginal. The analyses showed that there was an interaction between PI and smoking, implying that the effect of smoking on alveolar bone loss was increased in individuals with high PI values. Furthermore, a tendency was found for a dose-response effect of tobacco consumption. This tendency almost disappeared when controlling for PI.

The snuff-induced lesion. A clinical and morphological study of a Swedish material.

Snuff-induced oral lesions were studied clinically, histologically and by electron microscopy. The material was collected from 21 male snuff users. The lesions had a characteristic whitish appearance with a wrinkled swollen texture and the most common localization was in the vestibular area of the upper jaw. In two cases gingival retraction was observed. The light-microscopical examination showed a mild epithelial dysplasia in five cases. No carcinoma in situ or invasive carcinoma was recognized. In some of the cases ultrastructural changes in the basement lamina region, such as defects of the basement lamina and the occurrence of basal cell processes in the connective tissue, were observed. Odland bodies were seen in the epithelium. In the connective tissue filamentous material of unknown nature was found. The ultrastructure of the filamentous material suggested that it might be amyloid. In summary, snuff-induced lesions should be diagnosed, patients should be informed and made to quit the habit, and remaining lesions should be followed up regularly.

Chemokines Are Upregulated During Orthodontic Tooth Movement

In the early stage of orthodontic tooth movement, an acute inflammatory response characterized by the migration of leukocytes occurs. This response suggests the presence of specific chemotactic signals that may play a role in the mechanism of bone remodeling, in particular in resorption. The aim of the present study was to explore the induction of potential chemokines at the resorption side during orthodontic tooth movement. Monocyte chemoattractant protein-1 (MCP-1), regulated on activation normal T cell expressed and secreted (RANTES), and macrophage inflammatory protein-2 (MIP-2) were examined by in situ hybridization using radioactive synthetic oligoneucleotide probes. Mesial movement of the upper first molars was performed with a fixed appliance for 3, 7, and 10 days. The results demonstrated that MCP-1, RANTES, and MIP-2 were highly expressed during orthodontic movement. On day 3, MCP-1 showed maximum induction in the pressure zone, followed in intensity by RANTES and MIP-2, although not in the contralateral control side. The induction of these chemokines had declined on day 7 and reached low levels on day 10. Our data suggest that chemokines are induced early in the application of force, and such induction may contribute to the early inflammatory response that may be responsible in part for the ensuing bone remodeling.

A computerized system to measure interproximal alveolar bone levels in epidemiologic, radiographic investigations: II. Intra-and inter-examiner variation study

The study was aimed at analyzing intra- and inter-examiner variations in computerized measurement and in non-measurability of alveolar bone level in a cross-sectional, epidemiologic material. At each interproximal tooth surface, alveolar bone height in percentage of root length (B/R) and tooth length (B/T) were determined twice by one examiner and once by a second examiner from x5-magnified periapical radiographs. The overall intra- and inter-examiner variations in measurement were 2.85% and 3.84% of root length and 1.97% and 2.82% of tooth length, respectively. The variations were different for different tooth groups and for different degrees of severity of marginal periodontitis. The overall proportions of non-measurable tooth surfaces varied with examiner from 32% to 39% and from 43% to 48% of the available interproximal tooth surfaces for B/R and B/T, respectively. With regard to the level of reliability, the computerized method reported is appropriate to cross-sectional, epidemiologic investigations from radiographs.

Ultrastructural changes in the plasma membrane in human oral epithelium

In an electron microscopic analysis of specimens from human oral epithelium representing different degrees of keratinization, attention was focused on the plasma membrane and the immediately adjacent intra- and extracellular structures. In the stratum granulosum the membrane-attached layer of cytoplasm, and in the stratum corneum the plasma membrane, changed in structure according to a most regular pattern which presumably reflected certain functional stages of the cell. In the stratum superficiale of nonkeratinized specimens the plasma membrane was unchanged, but a membrane-attached layer of condensed cytoplasm developed.

Virus-like particles in papillomas of the human oral cavity

In two out of four specimens of human oral papillomas studied by electron microscopy, virus-like particles were found in several nuclei of the parakeratinized surface epithelium. The size and structure of the particles closely resembled the papilloma viruses present in other types of human and animal papillomas as described in the literature. Furthermore, a filamentous structure and small irregularly shaped particles were seen in some of the other nuclei. It is suggested that these structures represent stages in viral transformation. The general significance of identification of virus-like particles and nonvirus-like agents in tissue specimens is discussed, and further studies outlined.

Orthodontic movement induces high numbers of cells expressing IFN-gamma at mRNA and protein levels.

Cytokines are important signaling proteins that are liberated during immune challenges and exhibit many modulatory activities. However, their role in periodontal modeling during orthodontic tooth movement is not fully understood. The aim of this study was to analyze effects of mechanical force during orthodontic tooth movement, in the pressure zone, on the induction of interferon-gamma (IFN-gamma) as a proinflammatory cytokine of Th1 type and interleukin-4 (IL-4)/IL-10 as anti-inflammatory cytokines of Th2 type. In 12 Wistar rats 40-45 days old, the maxillary first molar was moved mesially by means of a closed coil spring for 3, 7, and 10 days. The contralateral side served as a control. IFN-gamma, IL-4, and IL-10 mRNA were determined by in situ, hybridization, and protein levels of IFN-gamma was measured by immunohistochemistry. Induction of IFN-gamma at both mRNA and protein levels was significantly higher on the experimental side than on the contralateral control side on day 3. The signal gradually became stronger on day 7 and remained high on day 10. Cytokines of the Th2 type (IL-4 and IL-10) were not detected at all examined time points in both pressure and contralateral control sides. Considering the potential immunoregulatory roles played by IFN-gamma, our data suggest that IFN-gamma may be involved in periodontium remodeling during orthodontic tooth movement.

White sponge nevus (leukoedema exfoliativum mucosae oris): ultrastructural observations.

Biopsy specimens from the oral lesions of white sponge nevus (WSN) in thirteen patients were analyzed by electron microscopy. Several marked deviations from the normal ultrastructure were recorded. Similarities and dissimilarities with other hereditary disturbances affecting the epithelium are discussed. Profound disturbance of the tonofilament system, with atypical aggregation of tonofilaments, was observed. Odland bodies, which are numerous in keratinized epithelia and are extruded into the intercellular space prior to the exfoliation of the surface cells, were also abundant in the WSN specimens. Very little material originating from Odland bodies appears, however, in the intercellular space in WSN. Presumably, the Odland bodies fail to properly function enzymatically in WSN.

Augmented levels of macrophage and Th1 cell-related cytokine mRNA in submandibular glands of MRL/lpr mice with autoimmune sialoadenitis

MRL/Mp‐lpr/lpr (MRL/lpr) mice spontaneously develop destructive inflammation of the salivary and lachrymal glands resembling Sjögrens syndrome (SS), representing an animal model to study this disease. We used in situ hybridization with synthetic radiolabelled oligonucleotide probes to examine expression of mRNA encoding pro‐ and anti‐inflammatory cytokines in submandibular glands of 2, 3, 4 and 5‐month‐old MRL/lpr mice. Phenotypic composition of submandibular gland infiltrates was evaluated by immunohistochemistry. Cells expressing tumour necrosis factor‐alpha (TNF‐α), IL‐1β, IL‐6 and IL‐12 mRNA were strongly up‐regulated at about the time of onset of sialoadenitis, suggesting a role of these cytokines in development of the disease. Interferon‐gamma (IFN‐γ) and cytolysin mRNA‐expressing cells were gradually up‐regulated over the disease course up to 5 months of age, the time when sialoadenitis is at its height, favouring a role of these cytokines in progression of the disease as well. Low levels of IL‐10 and transforming growth factor‐beta (TGF‐β) mRNA‐expressing cells were observed at 2, 3 and 4 months of age, and were almost undetectable at 5 months. Maximum levels of CD4+, CD8+ and interdigitating/dendritic cells, as well as of MHC class II and MHC class I expression were seen at 3 months, with CD4+ outnumbering CD8+ cells. Maximum levels of macrophages were seen at 4 months of age. These data argue for a major role of the proinflammatory cytokines TNF‐α, IL‐1β, IL‐6, IL‐12, IFN‐γ and cytolysin in initiation and perpetuation of autoimmune sialoadenitis in MRL/lpr mice, probably in conjunction with an insufficiency of the anti‐inflammatory cytokines TGF‐β and IL‐10.