Search PubMed⌕ Search

Biomedical subjects

M J Somerman

Publications and source records attributed to M J Somerman.

At least 91 records · Page 5Linked to original sources
PubMed1991

Human periodontal cells initiate mineral-like nodules in vitro.

A primary objective in the treatment of periodontal diseases is the regeneration of the mineralized and soft connective tissue components of the attachment apparatus. Current theories suggest the cells of the periodontium have the capacity, when appropriately triggered, to actively participate in restoring connective tissues, including mineralized tissues. To evaluate further the role of such cells in periodontal homeostasis, periodontal ligament (PDL) cells and gingival fibroblasts (GF) were cultured and examined for alkaline phosphatase levels and for the ability to produce mineralized nodules in culture. These are two characteristics of osteoblast-like cells in vitro. The levels of alkaline phosphatase produced by these cells were determined by a modified kinetic assay and the ability of these cells to produce mineral-like nodules in vitro was evaluated by Von Kossa staining and light and electron microscopy. PDL cells had significantly higher levels of alkaline phosphatase when compared with gingival fibroblasts obtained from the same patient and the same passage, in vitro. Furthermore PDL cells, but not GF, were capable of producing mineral-like nodules in vitro. These results indicate differences in behavior between PDL cells and GF; such differences may prove important in designing appropriate clinical therapies directed at stimulating periodontal regeneration.

Alkaline Phosphatase↗
PubMed1991

Periodontal connective tissue.

Connective tissues of the periodontium are composed of cells and their related extracellular matrix components. For these tissues to respond appropriately during development and regeneration as well as in health, a precise regulation of cell-cell interactions and cell-substrata interactions must occur. Thus, in order to achieve more predictable clinical results, it is critical that the mechanisms and proteins and factors guiding tissue development, maintenance, and regeneration be understood at the cellular and molecular level. This has resulted in an increased emphasis on identifying components of the periodontium and subsequently determining how these proteins and factors regulate cell behavior. This review summarizes our current knowledge of the proteins and factors considered important to development, maintenance, and regeneration of periodontal tissues.

Cell Adhesion Molecules↗
PubMed1990

Expression of constitutive and inducible HSP70 and HSP47 is enhanced in cells persistently spread on OPN1 or collagen.

Cells persistently spread on OPN or collagen survive heat shock better than cells transiently spread on fibronectin or tissue culture plates. Thus, a central question is whether constitutively or inducible stress proteins are enhanced in cells grown on adhesive proteins that maintain a persistent spread cell shape. Levels of Hsp 72,73, and colligin/Hsp47 were determined by Western blot analyses. The inducible Hsp 72 was prominently expressed following heat shock in cells grown on OPN or collagen, but not in cells plated on fibronectin coated substratum or on tissue culture plates. Colligin/Hsp 47 and Hsp 73 manifested a similar pattern of expression indicating that these adhesive attachment proteins accommodate cell function through organization of cell architecture.

Cell Adhesion↗
PubMed1990

The expression of colligin/hsp47 after stress in human periodontal fibroblasts in vitro.

Fibroblasts from human periodontal ligaments were grown in vitro. The levels of collagen and total protein in these cells were compared with subject- and passage-matched gingival fibroblasts. In 3 subjects the levels of both were greater in ligament than in gingival fibroblasts. These increased levels were also associated with increased levels of proteins reacting with anti-colligin/hsp47 antibodies on SDS-PAGE. Ligament and gingival fibroblasts were subjected to heat shock, sodium arsenite and the amino acid analogue AZC. These studies showed that (a) sodium arsenite and AZC enhanced the cellular levels of hsp47 in both types of fibroblast, (b) the colligin/hsp47 levels expressed were associated with elevated levels of protein and collagen production and (c) the presence of colligin/hsp47 was decreased under conditions of serum deprivation.

Arsenic↗
PubMed1990

Characteristics of human periodontal ligament cells in vitro.

Periodontal ligament cells may have a role in the regulation of hard and soft periodontal tissues, but their specific function has yet to be determined. To evaluate further their role in periodontal homeostasis, they were examined for osteoblast-like behaviour; in vitro no characteristic osteoblastic responsiveness was found. Periodontal ligament cells gave a PGE2- and isoproterenol-mediated cAMP response, but did not respond in a similar fashion to calcitonin or PTH. When exposed to PGE2, isoproterenol, or 1,25(OH)2 vitamin D3, they did not exhibit an increase in protein production, as measured by [35S]-methionine incorporation. Immunofluorescent localization indicated that periodontal ligament cells produce a bone-associated protein, osteonectin. In addition, mRNA levels for osteonectin and bone proteoglycan I (biglycan) were detected in these cells, in vitro. This information should help to clarify the role such cells play in the regulation of periodontal tissues.

Biglycan↗
PubMed1990

Persistent spreading of ligament cells on osteopontin/bone sialoprotein-I or collagen enhances tolerance to heat shock.

Fibronectin (FN), bone sialoprotein-I (BSP-I), Type I collagen, and a number of synthetic peptides containing the integrin attachment sequence (RDG) were evaluated for their ability to affect stress tolerance in osteo-ligament cells (OL). The attachment and spreading of OL cells was determined by the method of Klebe (1974) and Akiyama et al. (1986). Survival from heat shock was evaluated after the methods of Gerner et al. (1976). These studies showed that FN, BSP-I, and synthetic RGD peptides enhance attachment of OL cells. Increased survival from heat was limited to cells spread on fibronectin, BSP-I, and Type I collagen. OL cells that persistently spread on BSP-I and Type I collagen had more survivors than cells demonstrating transient spreading on FN. These studies indicate that (a) cell spreading is a prerequisite for stress tolerance and (b) enhanced stress tolerance is mediated by protein sequences other than those immediately surrounding the RGD sites in native proteins.

Animals↗
PubMed1990

Expression of attachment proteins during cementogenesis.

There is general agreement that during development the extracellular environment plays a critical role in controlling cell differentiation. Data generated from numerous studies support the possibility that cell attachment proteins and their corresponding cell receptors are possible candidates for this role. In particular, our studies are directed at identifying attachment proteins in mature cementum and establishing the function of these proteins during root formation. Fractionation of guanidine HCL/EDTA extracts of cementum revealed the presence of a bone-associated attachment, BSP, as well as fractions containing as of yet undetermined attachment proteins. Immunofluorescent examination of 1st molar tissues during root formation, obtained from 7 day-old mice neonates, for bone-associated attachment proteins indicated that osteopontin is expressed in the area of Hertwig's epithelial root sheath, but not in the region of the dental papillae. However, dental papillae cells, considered to have the capacity to form cementum, attached to osteopontin coated dishes, in vitro. Thus, unique attachment proteins, as well as those previously identified, were found in mature cementum and during root development. Future studies focused on identifying attachment proteins of mature cementum and determining the spatial and temporal localization of these proteins, pre- and post-cementogenesis, will provide important information necessary for establishing the function of these proteins during root development.

Animals↗
PubMed1989

Cell attachment activity of the 44 kilodalton bone phosphoprotein is not restricted to bone cells.

Proteins that promote cell migration, attachment and spreading are considered to play an important role in the regulation of cell function. Recently, a 44 kilodalton bone phosphoprotein (44K BPP) was shown to enhance the attachment of gingival fibroblasts and osteoblasts in vitro. The potential importance of this attachment protein in the regulation of mineralized tissue homeostasis prompted us to evaluate its ability to promote the attachment and migration of several other cell types. All the fibroblast cell lines and non-transformed calvaria cell lines assayed exhibited enhanced attachment and spreading in response to 44K BPP. Rat osteosarcoma cells (ROS 17/2.8) expressing osteoblast-like features, exhibited enhanced attachment in response to 44K BPP, while non-osteoblast-like cells (ROS 25/1) obtained from the same osteosarcoma did not. Two epithelial cell lines, CCL4 and A431, demonstrated enhanced attachment when exposed to fibronectin or laminin, but not 44K BPP. Another epithelial-like cell line, HT 1080, derived from a fibrosarcoma, showed enhanced attachment in the presence of all three attachment proteins. Fibronectin, but not 44K BPP, promoted the chemotactic migration of fibroblasts. These studies indicate that the role of 44K BPP attachment protein in the regulation of cell behavior is not restricted to bone cells.

Animals↗
PubMed1989

Periodontal ligament cells and gingival fibroblasts respond differently to attachment factors in vitro.

One of the initial events required for regeneration of periodontal tissues lost due to disease is the establishment of connective tissue attachment to root surfaces. Thus, considerable research efforts have focused on developing reliable procedures to gain new connective tissue attachment. Our studies focus on evaluating agents for their ability to promote cell attachment and spreading using an in vitro assay. For these studies human gingival fibroblasts (GF) and human periodontal ligament (PDL) cells, after exposure to fibronectin; 44 kilodalton bone phosphoprotein (44K BPP-osteopontin) or guanidine EDTA extracts of bone, cementum, or dentin, were compared as to degree of cell attachment and spreading. Fibronectin equally enhanced attachment and spreading PDL cells and GF. In contrast, 44K BPP, as well as guanidine EDTA extracts of bone and cementum, preferentially promoted attachment of GF when compared with attachment of PDL cells. For both PDL cells and GF the attached cells exhibited spreading. The guanidine EDTA extract of dentin did not promote attachment of either cell type. These results suggest that PDL cells and GF have different attachment properties which need to be considered for investigations directed at developing regenerative periodontal treatments.

Bone and Bones↗
PubMed1989

Connective tissue-associated proteins in crevicular fluid: potential markers for periodontal diseases.

Tests for periodontal disease that are able to detect both ongoing and future loss of clinical attachment would be valuable assets in determining the diagnosis and treatment of periodontal diseases. We hypothesized that connective tissue-associated proteins could be detected in crevicular fluid and would reflect the biochemical activity of the periodontium in health and disease. To test this hypothesis, crevicular fluid samples obtained from patients with various states of periodontal disease were analyzed for the presence of several connective tissue-associated proteins using a dot blot assay. Two such proteins, osteonectin and N-propeptide alpha I type I collagen, were detected in crevicular fluid samples of patients with periodontal disease. Furthermore, the amount of these proteins detected in crevicular fluid appeared to increase with increased probing depth at the sampled site. These studies indicate that measurements of connective tissue-associated proteins in crevicular fluid may prove to be a valuable tool for diagnosing periodontal diseases.

Biomarkers↗
PubMed1988

Expression of heat stress proteins by human periodontal ligament cells.

The purpose of the present report was to document the stress response produced by physical and chemical abuses to human periodontal ligament cells, and to review some of the known functions of stress response proteins produced as a result of such treatments. For these studies human PDL cells were exposed to sublethal challenges of 43 degrees C heat, sodium arsenite and the amino acid analog L-azetidine-2-carboxylic acid (AZC). The cells were labelled with [35S]-methionine and the proteins produced were examined by autofluorography of SDS-PAGE gels. Heat challenges were shown to induce hsps with an apparent mol. wts. of 90K, 68-72K, 41-47K, and 36 K. Arsenite-treated cells produced similar hsps including a 30k protein not produced by other forms of stress. AZC treatment resulted in the production of apparent functionless hsps with apparent molecular weights of 90,000, 72,000, 68,000 and 36,000. The function of these proteins and their possible role in periodontal disease is discussed.

Arsenic↗
PubMed1988

A comparative study of human periodontal ligament cells and gingival fibroblasts in vitro.

Both periodontal ligament and gingival tissue are thought to harbor cells with the ability to stimulate periodontal regeneration, i.e., formation of new bone, cementum, and connective tissue attachment. To understand further the role of these cells in the regenerative process, we compared human periodontal ligament cells and gingival fibroblasts, both derived from the same patient, same passage, in vitro. Protein and collagen production was significantly greater in periodontal ligament cells when compared with that of gingival fibroblasts. In addition, periodontal ligament cells had higher alkaline phosphatase levels when compared with those of gingival fibroblasts.

Alkaline Phosphatase↗
PubMed1987

Mechanism of fibroblast attachment to bone extracellular matrix: role of a 44 kilodalton bone phosphoprotein.

While the exact mechanisms regulating bone homeostasis are unknown, it is generally accepted that factors with the capacity to regulate cell attachment and spreading play a role in osteogenesis. A 44 kDa bone phosphoprotein (44K BPP), isolated from rat bone and synthesized by osteoblasts, was evaluated for its role in attachment and spreading of fibroblasts. In uncoated plates, enhanced cell attachment and spreading were observed when fibroblasts were exposed to the 44K BPP. The attachment properties of the bone phosphoprotein are different from those of fibronectin, in that the 44K BPP did not promote cell attachment in type I collagen wells, as was seen with fibronectin. Also, 44K BPP continued to enhance cell attachment up to 24 h, whereas cell attachment declined in time with cells exposed to fibronectin. Cycloheximide did not alter 44K BPP promotion of cell attachment, indicating that de novo protein synthesis was not required. These studies suggest that the 44K BPP is important in the regulation of cell attachment and spreading at sites of mineralization.

Bone and Bones↗
PubMed1987

Enhancement by extracts of mineralized tissues of protein production by human gingival fibroblasts in vitro.

Non-confluent cell cultures were exposed to both guanidine and guanidine-EDTA extracts of cementum, dentine and alveolar bone, at concentrations from 2 to 50 micrograms/ml for 48 h. The cells were radioactively labelled during the last 24 h. Total protein production was measured via incorporation of radioactive proline; collagen production was estimated by digestion of the radioactive protein mixture with bacterial collagenase. All guanidine-EDTA extracts elicited statistically-significant increases in total protein production when compared to controls. At 50 micrograms/ml of extract, the increase in protein production was 340, 143 and 338 per cent for bone, cementum and dentine, respectively. Similar results were obtained for collagen production. Guanidine-EDTA extracts also stimulated an increase in the production of specific proteins, as ascertained by gel electrophoresis. In contrast, the guanidine extracts had no effect on either protein or collagen production. Thus the functions of gingival fibroblasts can be altered by proteins from associated mineralized tissues. Identification of such proteins and their biological functions would enhance knowledge of the mechanisms that regulate connective-tissue regeneration.

Alveolar Process↗
PubMed1987

Stimulation of mannose incorporation into rat osteoblastic osteosarcoma cells by parathyroid hormone.

Agents considered to alter cAMP accumulation in bone cells were evaluated for their effects on protein production and sugar incorporation by bone cells. Total protein production or mannose incorporation by cells and in media were measured by the amount of radioactivity incorporated into trichloroacetic-acid precipitable fractions. Incorporation of radioactive leucine into the cellular and secreted proteins was linear over 5 h; radioactive mannose incorporation was linear only up to 2 h. Cells were also incubated with selected agents and radioactive mannose or leucine for 2 h. Addition of parathyroid hormone (PTH), isoproterenol or dibutyryl cAMP to osteoblasts resulted in a significant increase in mannose incorporation; dibutyryl cGMP and butyric acid had no effect on mannose incorporation. None of the agents altered total protein production. Thus PTH stimulates mannose incorporation into osteoblasts and this effect is, at least in part, modulated by cAMP.

Animals↗