A novel human bone marrow stroma-derived cell line TF274 is highly osteogenic in vitro and in vivo

A novel, immortalized, human bone marrow stroma-derived cell line TF274 is described which has the ability to form bone both in vitro and in vivo. Under basal conditions these cells expressed alkaline phosphatase (ALP) and type I collagen genes which are characteristic of the osteoblast phenotype. ALP levels were upregulated in the presence of osteotropic agents such as parathyroid hormone (PTH), transforming growth factor beta (TGF-beta), and BMP-2. In addition, PTH also increased cAMP levels in these cells. The capacity of these cells to form bone in vitro was evaluated by culturing them in the presence of L-ascorbic acid and beta-glycerophosphate. Matrix mineralization in these cultures was assessed by Alizarin Red staining and increased 45Ca uptake. Under these conditions mineralized nodule formation was observed in less than 2 weeks. Northern analysis of TF274 cells at various times during the mineralization process indicated a temporal expression of the osteocalcin gene that is typically associated with differentiating osteoblasts. The osteogenic nature of TF274 cells was confirmed in vivo using the severe combined immunodeficient (SCID) mouse model. Antibodies to human leukocyte antigens (HLA), class I antigens, and human OKa blood group antigen were used to demonstrate that the lesions formed were of human origin. By 21 days, the lesion consisted of a homogeneous focus of ALP-positive cells containing areas of mineralized bone lined with tartarate-resistant acid phosphatase (TRAP) positive osteoclasts. Thus, the TF274 cells exhibit osteogenic potential both in vitro and in vivo. This immortalized cell line represents a consistent source of cells that can be used to study human osteoblast differentiation both in vitro and in vivo.

Antibodies to TR2 (herpesvirus entry mediator), a new member of the TNF receptor superfamily, block T cell proliferation, expression of activation markers, and production of cytokines

TR2 (TNFR-related 2) is a recently identified member of the TNFR family with homology to TNFRII. We have demonstrated previously that TR2 mRNA is expressed in resting and activated human T cells and that TR2-Ig partially inhibits an allogeneic mixed leukocyte proliferation response. We now characterize TR2 further by the use of specific mAbs. Flow-cytometry analysis using TR2 mAbs confirmed that resting PBL express high levels of cell surface TR2, and that TR2 is widely expressed on all freshly isolated lymphocyte subpopulations. However, stimulation of purified T cells with either PHA or PHA plus PMA resulted in decreased surface expression within 48 h of activation before returning to resting levels at 72 h. TR2 mAbs inhibited CD4+ T cell proliferation in response to stimulation by immobilized CD3 or CD3 plus CD28 mAbs. Assay of culture supernatants by ELISA showed inhibition of TNF-alpha, IFN-gamma, IL-2, and IL-4 production, which, for IL-2 and TNF-alpha was also confirmed by intracellular cytokine staining. Furthermore, expression of activation markers on CD4+ T cells, including CD25, CD30, CD69, CD71, and OX40 (CD134), was inhibited. TR2 mAbs inhibited proliferation in a three-way MLR, and a response to soluble recall Ag, tetanus toxoid. In conclusion, these results suggest that TR2 is involved in the activation cascade of T cell responses and TR2 mAbs prevent optimal T cell proliferation, cytokine production, and expression of activation markers.

Interaction of adrenomedullin with calcitonin receptor in cultured human breast cancer cells, T 47D

Human adrenomedullin (hADM), human calcitonin gene-related peptide (hCGRP), and salmon calcitonin (sCT)-activated adenylyl cyclase with EC50 values of 132, 764, and 0.5 nM, respectively, in human breast cancer cell line, T 47D. Treatment of T 47D cell membranes with near maximal concentrations of sCT, hADM and hCGRP had no additive effect on adenylyl cyclase activity. Salmon calcitonin (8-32)[sCT (8-32)], selective antagonist of calcitonin receptor, inhibited the activation of adenylyl cyclase by these three peptides. On the other hand, the putative ADM receptor antagonist, ADM (22-52), and CGRP receptor antagonist, CGRP (8-37), failed to inhibit ADM-, CGRP- or sCT-activated adenylyl cyclase. These results suggest that in T47D cells, both ADM and CGRP activated adenylyl cyclase through sCT receptors.

Characterization of a novel TNF-like ligand and recently described TNF ligand and TNF receptor superfamily genes and their constitutive and inducible expression in hematopoietic and non-hematopoietic cells

A novel (TL1), a recently described (TL2) TNF-like, and three recently described TNF receptor-like (TR1, TR2, TR3) molecules were identified by searching a cDNA database. TL1 and TL2 are type-II membrane proteins. TR2 and TR3 are type-I membrane proteins whereas TR1 appears to be a secreted protein. TL1, TL2, TR2 and TR3 were expressed in hematopoietic cells, whereas TR1 was not. Northern blots hybridized with the cDNA probes revealed multiple forms of RNA as well as inducible expression of TL1, TL2, TR2 and TR3. TL2 and TR3, in particular, were highly induced in activated CD4+ T cells. Radiation hybrid mapping localized TR1 and TL2 to 8q24 and 3q26, respectively, which are not near any known superfamily members. TL1 was mapped to 9q32, near CD30L (9q33) and TR2 and TR3 mapped to the region of chromosome 1 that contains the TNFR-II, 4-1BB, OX40 and CD30 gene cluster at 1p36. Only TR3 in this cluster possesses a death domain. Southern blot analysis revealed the presence of TL and TR genes in different mammalian species. TL2, TR1, TR2 and TR3 were recently described by others as TRAIL/Apo-2L, OPG, HVEM and DR3/WSL-1/Apo-3/TRAMP/LARD, respectively.

Comparison of aesthetic properties of tooth-colored restorative materials

The objective of this study was to compare the aesthetic properties of color and translucency of Vita shade-based tooth-colored restorative materials, including composite resins, a polyacid-modified composite resin, and resin-modified glass-ionomer cements via clinical discrimination by human evaluators. The hue/chroma, value, and translucency of the five different materials chosen to represent the range of commercially available tooth-colored restoratives were graded by 40 dental personnel against the body of their respective Vita shade tabs using a five-point scale (1 = very poor; 2 = poor; 3 = average; 4 = good; 5 = excellent). Results confirm the clinical observation that the hue/chroma, value, and translucency of the different materials evaluated do not match the Vita shade guide to which they are supposedly keyed. The aesthetic properties of hue/ chroma, value, and translucency for the material evaluated were all shade dependent. Comparison of pooled results revealed that none of the materials had good or excellent ratings and that the composite resins had significantly better hue/ chroma, value, and translucency match to the Vita shade guide than the other materials evaluated.

A newly identified member of the tumor necrosis factor receptor superfamily with a wide tissue distribution and involvement in lymphocyte activation

The tumor necrosis factor receptor (TNFR) superfamily consists of approximately 10 characterized members of human proteins. We have identified a new member of the TNFR superfamily, TR2, from a search of an expressed sequence tag data base. cDNA cloning and Northern blot hybridization demonstrated multiple mRNA species, of which a 1.7-kilobase form was most abundant. However, TR2 is encoded by a single gene which, maps to chromosome 1p36.22-36.3, in the same region as several other members of the TNFR superfamily. The most abundant TR2 open reading frame encodes a 283-amino acid single transmembrane protein with a 36-residue signal sequence, two perfect and two imperfect TNFR-like cysteine-rich domains, and a short cytoplasmic tail with some similarity to 4-1BB and CD40. TR2 mRNA is expressed in multiple human tissues and cell lines and shows a constitutive and relatively high expression in peripheral blood T cells, B cells, and monocytes. A TR2-Fc fusion protein inhibited a mixed lymphocyte reaction-mediated proliferation suggesting that the receptor and/or its ligand play a role in T cell stimulation.

Shade match of tooth-colored restorative materials based on a commercial shade guide

Many restorative materials are claimed by their manufacturers to match the Vita shade guide. To verify this claim, 40 dental personnel were asked to color match five different restorative materials to their respective Vita shade tabs according to a 5-point scale (1 = very poor color match; 5 = excellent color match). Three shades were chosen for each restorative material (a mid-Value shade as well as the highest Value shade and the lowest Value shade present in each system). Pooled scores indicated that the resin composite materials had significantly better overall shade match than did the other materials evaluated and that one resin-modified glass-ionomer cement had significantly better shade match than did the "compomer" and another resin-modified glass-ionomer cement. Only 11% of the scores for all material and shade combinations were given a good or excellent rating (score greater than 3). Shade match to the Vita shade guide was not material dependent but tended to differ among the different Value shades evaluated.

The use of multiplanar reformatted computerised tomography in the surgical-prosthodontic planning of implant placement

Presurgical planning and communication between the prosthodontist and the surgeon is essential to achieve optimal placement of functional implants. Besides the basic clinical examination and the use of mounted study models, radiographic imaging is an essential adjunctive aid in treatment planning. The latest imaging modality, multiplanar reformatted CT (MPR-CT) is the most comprehensive and accurate presently available. It allows precise assessment of the three-dimensional architecture and internal anatomy of the jaws. This enables accurate preoperative evaluation for planning implant fixture placement with maximal use of bone. It's widespread use would prevent unsuitable cases from ever reaching surgery. MPR-CT is described in detail and its usefulness in treatment planning the dental implant case illustrated. Indications, contraindications, advantages and disadvantages will be discussed. The use of radiographic stents derived from diagnostic wax-ups or set-ups is essential. The incorporation of suitable radiographic markers provide both the surgeon and prosthodontist with reference points to determine the available bone at the exact spatial location and orientation of the planned implant fixture at all primary and alternate sites. The same radiographic stent is then converted to a surgical guide stent for precise location of surgical implant sites.

The clinical significance of distortion in implant prosthodontics: is there such a thing as passive fit?

Passive fit of the implant prosthesis onto osseointegrated and functional fixtures intraorally is the "Holy Grail" of the discerning implant prosthodontist. There is growing recognition that the old and "tried" clinical procedures and laboratory fabrication methods transferred from traditional fixed and removable partial denture prosthodontics, fall short of achieving true passivity of fit. The stages of impression making, master cast, resin verification jig, waxing, investing, casting, veneer addition and finishing can all add to the final distortion of the prosthesis. Studies are emerging that report the possible distortion associated with each stage. Alternative strategies have also been suggested to by-pass these traditional stages, for example laser welding or the elimination of the impression using optical digitising and CAD-CAM. In the final analysis, totally "passive" fit is probably unachievable. The challenge is to determine a minimum level of distortion and associated stress that is acceptable and that confers adequate clinical longevity to the prosthesis. Developing clinical tests that measure stress levels intraorally as the prosthesis is fitted would be the ideal gold standard by which to judge the accuracy of fabrication procedures. This paper summarises and rationalises the growing body of literature dealing with accuracy of implant prosthodontic procedures.

Three-dimensional analysis of the casting accuracy of one-piece, osseointegrated implant-retained prostheses

The three-dimensional distortions of implant frameworks of two designs, reflecting the early "Toronto" U-shaped design and a current L-shaped design, were measured. A conventional commercial laboratory one-piece casting method, using a silver-palladium alloy, was used. Distortion was defined by five displacement variables for the centroids of each of five gold cylinders incorporated in each casting: three orthogonal translational displacements (dx, dy, and dz) and two rotational displacements (d theta x and d theta y). A computerized coordinate measuring machine was used. Overall translational displacements measured were -17.4 +/- 15 microns for dx, 6.1 +/- 7.1 microns for dy, and -0.1 +/- 1.7 microns for dz. The overall global translational displacement, dR, was 20.2 +/- 14.5 microns. Overall rotational displacements were -0.098 +/- 0.109 degrees for d theta x and -0.020 +/- 0.097 degrees for d theta y, giving an average absolute angular change, d theta R, of 0.158 +/- 0.077 degrees. No significant differences were found between U- and L-shaped castings, except for dy values for cylinders 2, 3, and 4, and d theta x values for cylinder 1. Cylinder location within the arch was associated with a specific direction and magnitude of translational and rotational displacement. Even small rotational displacements may manifest large gap appearances with the one-screw test because of the "moment arm" effect. However, other rotational displacements may be hidden, depending on the direction of tilt and the moment arm length.

Amplification of the topoisomerase ii α gene in a non-small cell lung cancer cell line and characterisation of polymorphisms at the human topoisomerase ii α and β loci in normal tissue

DNA was prepared from normal tissue and 19 lung cancer cell lines. Using probes which detect restriction fragment length polymorphisms at both the topoisomerase II alpha and beta loci, heterozygosity was detected at a frequency of 0.17 and 0.37 for the alpha and beta loci, respectively. Southern blot analysis of DNA extracted from lung cancer cell lines detected amplification of both the topoisomerase II alpha and ERBB2 genes in the adenocarcinoma line Calu3. These results indicate that topoisomerase II alpha and ERBB2 may be closely linked on chromosome 17 and coamplified during adenocarcinoma progression. Since topoisomerase II is a target for several anticancer drugs, it will be of interest to study alterations to topoisomerase II genes during tumour development, as these may in part determine the response of the tumour to chemotherapy.

Topoisomerase II alpha and topoisomerase II beta genes: characterization and mapping to human chromosomes 17 and 3, respectively

Human cells contain two topoisomerase II isozymes named topo II alpha and topo II beta. The complementary DNAs for both enzymes have been cloned. The topo II alpha and topo II beta complementary DNAs hybridized to unique sequences of human, rodent, and chicken DNAs in Southern blots. The human topo II alpha gene has previously been mapped to chromosome 17. We confirmed the chromosomal location of topo II alpha and mapped the topo II beta gene to chromosome 3. In addition, topo II beta exhibits genetic polymorphism as has been reported for topoisomerases I and II alpha.

Auditory canal haemorrhage following mandibular condylar fracture

A case of haemorrhage from the external auditory meatus associated with condylar fracture is presented. It is important that haemorrhage from the ear following maxillofacial injuries be investigated thoroughly because displacement of the condyle into the middle cranial fossa also presents in this manner. The patient was treated by intermaxillary fixation and packing of the auditory canal. Packing is not only effective for haemostasis but is also important in preventing subsequent stenosis of the auditory canal.

Development of a stable camptothecin-resistant subline of P388 leukemia with reduced topoisomerase I content

A camptothecin-resistant subline of P388 leukemia (P388/CPT) was developed by repeated transplantation of P388 cells in mice treated with therapeutic doses of camptothecin. In mice bearing the resistant tumor, a maximally tolerated dose of camptothecin produced no net reduction in tumor cell burden, in contrast to a 5-log cell kill in the parental P388 (P388/S). The IC50 of camptothecin, as determined by colony formation assays of cultured cells, was 8 times greater for the cloned P388/CPT cell line than for P388/S. P388/CPT cells were not cross-resistant to other antineoplastic agents, including topoisomerase II inhibitors. The type I topoisomerases purified from P388/CPT and P388/S cells were identical with respect to molecular weight, specific activity, in vitro camptothecin sensitivity, and DNA cleavage specificity. Camptothecin induced fewer protein-associated DNA single-strand breaks in the resistant cells than in the wild-type P388 cells. Topoisomerase I mRNA, immunoreactivity, and extractable enzymatic activity were 2-4 times lower for P388/CPT cells than for P388/S cells. As resistance to camptothecin developed, topoisomerase I extractable activity decreased, concomitant with an increase in topoisomerase II extractable activity. Furthermore, the appearance of camptothecin resistance was associated with specific rearrangements of the topoisomerase I gene. These results suggest that development of resistance to inhibitors of topoisomerase I can occur by down-regulation of the target enzyme, thus reducing the production of lethal enzyme-mediated DNA damage. The enhanced topoisomerase II activity in these cells suggests that resistance to camptothecin may be overcome by co-treatment with topoisomerase II inhibitors.

Characterization and immunological identification of cDNA clones encoding two human DNA topoisomerase II isozymes

Several DNA topoisomerase II (Topo II; EC 5.99.1.3) partial cDNA clones obtained from a human Raji-HN2 cDNA library were sequenced and two classes of nucleotide sequences were found. One member of the first class, SP1, was identical to an internal fragment of human HeLa cell Topo II cDNA described earlier. A member of the second class, SP11, shared extensive nucleotide (75%) and predicted peptide (92%) sequence similarities with the first two-thirds of HeLa Topo II. Each class of cDNAs hybridized to unique, nonoverlapping restriction enzyme fragments of genomic DNA from several human cell lines. Synthetic 24-mer oligonucleotide probes specific for each cDNA class hybridized to 6.5-kilobase mRNAs; furthermore, hybridization of probe specific for one class was not blocked by probe specific for the other. Antibodies raised against a synthetic SP1-encoded dodecapeptide specifically recognized the 170-kDa form of Topo II, while antibodies raised against the corresponding SP11-encoded dodecapeptide, or a second unique SP11-encoded tridecapeptide, selectively recognized the 180-kDa form of Topo II. These data provide genetic and immunochemical evidence for two Topo II isozymes.

Nonproductive rearrangement of DNA topoisomerase I and II genes: correlation with resistance to topoisomerase inhibitors

Topoisomerase inhibitors comprise an important group of agents that is used in cancer treatment. Because the development of resistance to cancer chemotherapeutic agents represents a major limitation of cancer chemotherapy, we investigated the mechanism of resistance by murine P388 leukemia to camptothecin (topoisomerase I inhibitor) or amsacrine (topoisomerase II inhibitor). The resistant cells contained reduced levels of topoisomerase activity and messenger RNA. The topoisomerase gene of these cells was rearranged (only in one allele) and hypermethylated. These topoisomerase gene alterations probably resulted in reduced transcription and, thus, enzyme production, which was correlated with resistance to the topoisomerase inhibitor.

Altered actin and immunoglobulin C mu expression in nitrogen mustard-resistant human Burkitt lymphoma cells

Raji-HN2 is a B cell lymphoma (Burkitt lymphoma) line that was made resistant to nitrogen mustard. The drug-resistant phenotype was accompanied by changes in gene expression. The expression of four unrelated genes was examined by Northern blot analysis. Raji-HN2 cells were found to contain about twice the number of actin mRNA found in Raji cells. Both cell lines were found to contain equivalent amounts of beta 2-microglobulin, c-myc oncogene, and immunoglobulin C mu mRNAs. The C mu mRNA was, however, larger in size in Raji-HN2 cells. Alterations in actin and C mu mRNAs in Raji-HN2 cells were not due to gene amplification or rearrangement because Southern blot analysis revealed no changes in the genomic organization of these genes. The increased actin mRNA content was correlated with an increased actin content of Raji-HN2 cells. The F-actin (stained with 7-nitrobenz-2-oxa-1,3-diazolylphallacidin) content of single cells was quantitated in a meridian interactive laser cytometer. Raji-HN2 cells contained about twice the amount of F-actin present in the parental Raji cells. Similar results were obtained when large populations, 10(6) cells each, were examined in a flow cytometer.

Evidence for the participation of topoisomerases I and II in cadmium-induced metallothionein expression in Chinese hamster ovary cells

CHO-Cdr20 cells are 10-20 times more resistant to killing by cadmium than the parental CHO cells. Resistance has been linked to amplification of the metallothionein genes MT-I and MT-II and their coordinate induction by cadmium and other toxic metals. We studied the roles of the nuclear enzymes topoisomerase I and topoisomerase II in Cd-induced expression of MT-II. Camptothecin-induced DNA strand breakage, mediated by topoisomerase I in cells, increased by approximately 20% when the resistant cells were incubated first with 50 microM Cd and then with camptothecin. Short DNA fragments were enriched in MT-II-hybridizing sequences, indicating that topoisomerase I-associated breakage was directed in part toward the location of induced gene activity. Ten microM camptothecin inhibited Cd-induced accumulation of MT-II mRNA as well as induced and uninduced RNA synthesis in the resistant cells. These data are consistent with the notion that topoisomerase I participates in most or all forms of RNA synthesis. Topoisomerase II inhibitors which trap cleavable complexes (amsacrine, VM-26, VP-16) increased DNA strand breakage at very high concentrations (50-100 microM); the increased breakage appeared to be concentrated near the MT-II gene. This class of inhibitor did not block the accumulation of MT-II message. Novobiocin, a second type of topoisomerase II inhibitor blocked transcription at 300 microM. Merbarone, a novel, third type of topoisomerase II inhibitor, blocked MT-II transcription at 50-100 microM. The latter two inhibited total RNA synthesis in induced, but not uninduced cells. Thus, it is possible that topoisomerase II plays more than one role in transcription and that more than one form of this enzyme is involved.

Elevated DNA topoisomerase II activity in nitrogen mustard-resistant human cells

A human Burkitt lymphoma cell line, Raji-HN2, made 10-fold more resistant to nitrogen mustard (HN2) than the parental Raji cell line, exhibited the following characteristics when compared to the parental Raji cells: (i) decreased HN2-induced DNA interstrand crosslinking; (ii) increased (3-fold) DNA topoisomerase II [DNA topoisomerase (ATP-hydrolyzing), EC 5.99.1.3] activity; (iii) increased (4- to 11-fold) sensitivity to topoisomerase II inhibitors; (iv) increased (2-fold) glutathione content; and (v) increased (2-fold) cell doubling time. The resistant phenotype was unstable and was maintained by weekly treatment of the cells with HN2. Growing the resistant cells in the absence of HN2 resulted in a time-dependent decrease in both resistance to HN2 and topoisomerase II activity and an increase in DNA interstrand crosslinking induced by HN2. We hypothesize that HN2 resistance is due to enhanced monoadduct repair with resultant decreased DNA crosslinking and that this process is mediated by topoisomerase II.

Normal and neoplastic human cells have different histone H1 compositions

The H1 histone is the least conserved of the five major groups of histone proteins. There are as many as five subtypes of H1 histone (1-3). These H1 subtypes occur in different amounts in different animal species and also show tissue specificity (1-3). Normal and neoplastic tissues from the same animal, e.g. rat or calf, contain the same H1 subtypes but in different relative amounts (4, 5). Because H1 subtypes exhibit tissue specificity, it is therefore difficult to identify the changes in their composition that are associated with neoplasia reported in studies utilizing tissues of different origins (4, 5). Tissue culture cells and their in vitro transformed neoplastic counterparts, on the other hand, offer an excellent system in which to study these changes because the cells are derived from the same origin. We have examined normal and neoplastic human cells and found a relationship between the H1 composition and the ability of the cells to form tumors in nude mice. The ratio of H1A to H1B in normal human cells is considerably lower than that in neoplastic cells and this ratio increases with the increased ability of the cells to form tumors in nude mice.

Transcriptional control of the expression of mouse globin genes in myeloma x erythroleukemia cell hybrids

Fusions were made between thymidine kinase deficient (TK-) Friend Cells inducible for hemoglobin production, and immunoglobulin-producing, hypoxanthine-guanine phosphoribosyltransferase-deficient (HGPRT-) myeloma cells. Hybrids were selected in hypoxanthine-aminopterin-thymidine (HAT) and identified by isozyme analysis and chromosome counts. All hybrids resembled the myeloma cell line in mode of growth and were immunoglobulin secretors. All hybrids did not express hemoglobin and were uninducible for hemoglobin production with dimethyl sulfoxide (DMSO). Hybridization of genomic globin DNA probes with hybrid-derived nuclear and cytoplasmic mRNAs blotted to nitrocellulose filter indicated that lack of expression of the globin genes in the hybrids was due to lack of transcription.

Chromosomal proteins of mouse teratocarcinoma cells

We have analyzed chromosomal proteins extracted from murine teratocarcinoma-derived stem cell lines (F9 and 12-1) and from their differentiated derivatives (12-1a) because of the differential sensitivity to DNase I digestion of these two cell types. The chromosomal DNA of stem cells is more sensitive to DNase I digestion than that of differentiated cells. Stem cell core histones are more highly acetylated than their differentiated counterparts, and certain high-mobility group (HMG) proteins from stem cells (HMG 1 and HMG 2) are found in greater amounts than in the differentiated cells though others (HMG 14 and HMG 17) occur in similar amounts. We have also identified a new HMG protein (HMG 9) that is present in stem cells and is lost following differentiation.