bluuebunny/crossref_metadata_2025 huggingface dataset:
Alterations of neutrophil L‐selection and CD18 expression by tobacco smoke: implications for periodontal diseases
Authors: Ryder Mark I. , Fujitaki Ron , Lebus Scott , Mahboub Mahyar , Faia Brandi , Muhaimin Dawud , Hamada Makoto , Hyun William
Published: July 2006

Alterations in neutrophil functions by both chronic low levels of tobacco and by acute short‐term higher levels of tobacco smoke, as encountered during the act of smoking, may play a role in the pathogenesis of periodontal diseases in smokers. Among the early migration events of neutrophil function is the alteration in surface expression of L‐selectin and the CD11/18 integrins. In the present study we examined the effect of in vitro smoke exposure and nicotine alone on the expression of these 2 adhesion molecules in neutrophils from smokers and non‐smokers. We also determined the physiological relevance of this in vitro system by assessing the levels of nicotine exposure in this in vitro system and comparing these levels to acute and chronic levels of nicotine in saliva and gingival crevicular fluid. Peripheral neutrophils were isolated from the blood of smokers (> 1 pack/d) and non‐smokers and incubated in vitro with either cigarette smoke (0–5 min), 10−7 M F‐met‐leu‐phe, or nicotine alone at 1.62mg/ml to 162ng/ml (10−2 M‐10−6 M). The neutrophils were then incubated with fluoresceine conjugated anti‐Leu8 (L‐selectin), anti‐CD18 (CD18 integrin), or γ‐4 (non‐specific control), fixed and analyzed by flow cytometry. With cigarette smoke exposure, there was an approximate 75% shedding of L‐selectin in both smokers and non‐smokers with no marked difference between groups at 1–5 min of smoke exposure. Cigarette smoke exposure resulted in a 15–20% increase in CD 18 expression in both smokers and non‐smokers. At all time points, there was slightly greater but statistically insignificant expression of CD18 integrin in non‐smokers when compared to smokers. These patterns of CD18 increases and L‐selectin shedding were similar in magnitude to incubations with 10−7 M F‐met‐leu‐phe. Acute smoke exposure resulted in elevation of nicotine in the smoke box to 529 ng/ml at 5 min, in saliva from 109.2 ng/ml before smoking to 1821.4 ng/ml after smoking, and in gingival crevicular fluid to 5961 ng/ml after smoking. No significant alterations in L‐selectin or CD 18 expression were noted with in vitro nicotine from 1.62 mg/ml to 162 ng/ml.
Alkaline phosphatase activity in human periodontal ligament: age effect and relation to cementum growth rate*
Authors: van den Bos T. , Beertsen W.
Published: July 2006

Recently, a relationship was demonstrated between the thickness of the cementum layer in rat molars and the activity of alkaline phosphatase (ALP) in the adjoining periodontal ligament (PDL). It was the aim of the present study to investigate whether such a relationship also exists in the periodontium of man. Healthy deciduous and permanent teeth free from periodontitis were obtained from 74 patients, varying in age from 3 to 78 yr, and their PDL dissected from the middle one‐third of the roots. ALP activity was measured in PDL extracts and expressed per hydroxyproline content. It was shown that ALP activity was relatively high in children. After puberty its concentration decreased to level off at about half the concentration found in the younger age groups. The activity of the enzyme in the PDL correlated positively with the yearly cementum thickness increment as calculated from data published previously.
Cyclosporin A‐induced gingival overgrowth in the rat: a histological, ultrastructural and histomorphometric evaluation
Authors: Ayanoglou C. M. , Lesty C.
Published: July 2006

This investigation was undertaken to further study cyclosporin A (CsA)‐induced gingival overgrowth. Thirty mg/kg/d of vehicle or CsA solutions were given orally to 6‐wk‐old male Sprague‐Dawley rats. After 4, 9, 14 and 19 wk 2 control and 2 experimental rats were anaesthetized, tissues fixed by intracardiac perfusion of fixative solution and jaws processed for Epon inclusion. Histological and ultrastructural studies conducted in a gingival portion (free gingiva) revealed the presence of hyalinization areas and of multinucleated cells (MCs) containing collagen fibrils (connective tissue), of amorphous areas and disorders of keratinization (epithelia). Histomorphometric evaluation indicated that in the CsA rats the mean cross‐sectional area of the free gingiva was 2.52‐fold increased compared to the controls. The connective tissue comprised 41.43% of this area (instead of 31.49% in controls). Additional histomorphometric evaluation was performed in 3 groups of free gingival portions: control (C group), CsA‐non‐respondent (CsA‐nR) and CsA‐respondent (CsA‐R). The cross‐sectional gingival areas studied were slightly lower than the mean area of all the control sites previously defined (groups C and CsA‐nR) or showed the higher degrees of enlargement (CsA‐R). In the CsA‐R group the mean cross‐sectioned area of the vessel profiles was increased and the number of fibroblast profiles decreased. In the CsA‐nR group the number of vessel profiles and that of MCs profiles were increased. In the epithelia of the CsA‐R group were increased (a) keratinized epithelia: thickness; thickness of the inner and of the outer compartments; surface area of spinous cell profiles; (b) oral gingival epithelium: number of cell layers (inner compartment); (c) oral sulcular epithelium: surface area of granular cell profiles; (d) junctional epithelium: thickness; number of cell layers. These results indicate that (a) the CsA induced modifications are not limited to enlarged gingiva (b) the overgrowth of the GCT is the result of a vasodilatation and of an increase in the volume of the extracellular matrix and (c) the increase of the epithelial thickness is mainly the result of a cell hypertrophy in the keratinized epithelia and of a cell hyperplasia in the junctional epithelium.
Lipopolysaccharide from Actinobacillus actinomycetemcomitans stimulates production of interleukin‐1 β, tumor necrosis factor‐α, interleukin‐6 and interleukin‐1 receptor antagonist in human whole blood
Authors: Blix I. J. Schytte , Helgeland K. , Hvattum E. , Lyberg T.
Published: July 2006

Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) is supposed to be an important etiological agent in localized juvenile periodontitis (LJP). We have studied the effect of lipopolysaccharide (LPS) extracted from these periodontopathogenic bacteria on synthesis of the proinflammatory cytokities, interleukin‐1β (IL‐1β), tumor necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6) and the anti‐inflammatory cytokine IL‐1 receptor antagonist (IL‐lra) in human whole blood. LPS from A. actinomycetemcomitans in concentrations ≥ 1 ng/ml induced a significant production of all these proinflammatory cytokines, whereas LPS from Escherichia coli (E. coli), strain 026:B6 had to be added in concentrations ≥1 μg/ml to obtain a similar effect. Similarly, LPS from A. actinomycetemcomitans≥0.1 ng/ml resulted in production of IL‐1ra, while LPS from E. coli 026:B6 had to be added at ≥10 ng/ml to obtain similar effects. It has been suggested that the ratio between production of proinflammatory and anti‐inflammatory cytokines may influence the outcome of periodontal diseases. Other in vitro and in vivo studies have, however, indicated that very large excesses (100‐1000 times) of IL‐1ra compared to IL‐1β are required to shift the IL‐1ra:IL‐1β ratio in favor of an inhibition of IL‐1 bioactivity. In our ex vivo system, we found that stimulation with extremely low doses of A. actinomycetemcomitans LPS (0.1‐1 ng/ml) resulted in IL‐1ra production solely, without concomitant production of IL‐1β, the excess of IL‐1ra over IL‐1β peaking at 1 ng/ml, which accordingly should suggest that LPS from A. actinomycetemcomitans primarily has proinflammatory effects.
Calibration of the Periotron 8000® and 6000® by polynomial regression
Authors: Chapple I. L. C. , Landini G. , Griffiths G. S. , Patel N. C. , Ward R. S. N.
Published: July 2006

This paper reports the detailed calibration of the new Periotron 8000® with different fluids and uses the method of least squares to derive polynomial regression equations up to the 6th order, to investigate the most accurate descriptor of the resulting calibration lines. The use of a 4th order polynomial regression equation (recommended by the manufacturer) provided better coefficients of determination (R2: 0.999) and root mean square errors (RMSE = 1.6) than either linear regression (R2: 0.986, RMSE = 10.9) or quadratic models (R2: 0.998, RMSE = 3.2). Data derived using the manufacturer's MLCONVERT software program lacked accuracy and incurred large errors for volumes > 0.5 μl. Calibrations performed on one day could be used with accuracy to derive volumes >0.1 μl collected on subsequent days, when using the same machine (s.d. for residuals plot=2.49 Periotron units), but this was not the case for different machines (s.d. = 9.57 Periotron units). Varying serum protein concentration by up to 500% had a negligible effect on calculated volumes above 0.1 μl. We conclude that the Periotron 8000® is at least as reliable a machine as the Periotron 6000®, and that the calibration lines for both machines are best described using 4th order polynomial regression equations and “look‐up” tables, rather than quadratic (Periotron 6000®) or the manufacturer's software (Periotron 8000®). Serum seems to be an acceptable GCF substitute for calibrations, which can be performed 1 day, and used on subsequent days for a given machine and for volumes above 0.1 μl.
Induction of anti‐thymocyte/T lymphocyte antibodies in mice injected with lipopolysaccharides from periodontopathic bacteria
Authors: Kaneko Takashi , Hara Yoshitaka , Yoshimura Atsutoshi , Kato Ihachi
Published: July 2006

We examined the levels of anti‐thymocyte/T lymphocyte autoantibody (ATA) in the serum of mice injected intraperitoneally with lipopolysaccharides (LPS) from periodontopathic bacteria; Porphyromonas gingivalis, Actinobacillus actinomyceterncomitans, Fusobacterium nucleatum, Capnocytophaga ochracea, and non‐oral Escherichia coli. All of the LPS induced IgM‐ATA. Among these, LPS from C. ochracea induced the highest level of IgM‐ATA, whereas that of P. gingivalis induced the lowest. The peritoneal T lymphocytes of mice injected with LPS were bound by IgM‐ATA. Peritoneal B‐1 (CD5+B) cells stimulated by each LPS produced much more IgM‐ATA than splenic B‐2 (CD5− B) cells, suggesting that B‐1 cells might be responsible for the production of these antibodies. Serum of mice injected with C. ochracea and F. nucleatum LPS showed cytotoxicity against thymocytes in the presence of rabbit complements. Binding and cytotoxicity were confirmed by IgM purified from serum of the mice injected with C. ochracea LPS. Furthermore, serum of mice treated with C. ochracea, F. nucleatum or A. actinomycetemcomitans LPS inhibited the proliferation of thymocytes. However, purified IgM from the serum of mice treated with C. ochracea LPS failed to produce the same inhibition. Our results suggest that LPS from certain species of periodontopathic bacteria can induce IgM‐ATA in the serum and these antibodies may modulate the local immune network in periodontal tissues.
Porphyromonas gingivalis lipopolysaccharide delays human polymorphonuclear leukocyte apoptosis in vitro
Authors: Preshaw Philip M. , Schifferle Robert E. , Walters John D.
Published: July 2006

Apoptosis (programmed cell death) is a mechanism by which superfluous or damaged cells undergo changes that lead to selective removal from organ systems by phagocytic cells. Certain bacterial products delay apoptosis in neutrophils (PMNs). In this study, PMNs were incubated for up to 8 h with varying concentrations of lipopolysaccharide (LPS), lipid A or capsular polysaccharide isolated from 3 strains of Porphyromonas gingivalis (Pg) (strains HG‐184, A7A1‐28 and 381). Assay runs included controls containing cells and medium but no bacterial products. Fluorescence microscopy was used to evaluate apoptotic changes. PMNs exhibited a time‐dependent increase in the number of apoptotic cells. When cells were cultured in the presence of LPS from any of the 3 Pg strains, apoptosis was delayed in a dose‐dependent fashion (p <0.05). The effects of these LPS preparations were similar to each other and to Escherichia coli 0111:B4 LPS. Lipid A from the 3 Pg strains also delayed apoptosis (p<0.05), but was less potent than LPS or synthetic lipid A. Capsular polysaccharide had no significant effect on apoptosis (p > 0.05). Thus, LPS and lipid A from P. gingivalis appear to modulate the functional lifespan of PMNs. This could potentiate the inflammatory and destructive components of periodontal diseases.
Angiotensin‐II increases cytoplasmic calcium, cell number and total DNA for human periodontal ligamental cells in vitro
Authors: Lundergan W. P. , Ferry D. , Kobayashi H. , Snowdowne K. W.
Published: July 2006

The identification and the development of potential growth factors for the cells of the periodontal ligament is an important and novel stratagem for the regeneration of tissue destroyed by periodontal pathogens. The problem is that growth factors are difficult to synthesize, very immunogenic and expensive. The purpose of our study was to determine if angiotensin‐II, a naturally occurring octo‐peptide with growth‐factor like properties in cardiac muscle, could also stimulate cultured human periodontal ligament cells. If angiotensin‐II does have growth factor properties, then it should be able to increase cytoplasmic calcium (a secondary messenger associated with mitogenesis) and to increase fibroblast proliferation. Fura‐2 fluorescence and aequorin photometry were used to follow changes in cytoplasmic calcium. Cytometry and total amount of DNA were used to measure proliferation evoked by angiotensin‐ll. We found that angiotensin‐II increased cytoplasmic calcium, the total amount of DNA and cell number, suggesting that angiotensin‐II has mitogenic properties for cells isolated from human periodontal ligament.
Enhancement of LPS‐stimulated plasminogen activator production in aged gingival fibroblasts
Authors: Mochizuki K. , Yamaguchi M. , Abiko Y.
Published: July 2006

Plasminogen activator (PA) converts plasminogen to plasmin, and plasmin activates the kinin cascade and latent methalloproteases. It is known that the alteration of the PA‐plasmin system affects the progression of periodontal disease. We have reported previously that LPS from Campylobacter rectus, which is associated with adult periodontitis, increased PA production in human gingival fibroblasts (hGF). The effects of in vitro‐ and in vivo‐ cellular ageing on PA production from human and rat gingival fibroblasts (rGF) were studied. In vitro cellular aged hGF were prepared by subcultivations of hGF, and in vivo aged rGF was cultured primarily from the gingival tissue of aged rats. The cells were challenged with LPS and PA released into the cultured medium was measured as PA activity. Both in vitro and in vivo cellular aged GFs produced a significantly higher PA activity by LPS compared with young GFs cell. In RT‐PCR experiments, tissue type PA (tPA) mRNA levels in both aged hGF and rGF were higher than in young cells, whereas plasminogen activator inhibitor I (PAI‐l) mRNA remained unchanged and urotype PA (uPA) mRNA was not detected. Since LPS‐stimulated PA activity from gingival fibroblasts was stimulated in aged cells using both in vitro‐ and in vivo‐ experimental models, the ageing of gingival fibroblasts may have an effect on the severity of inflammation and degradation of the extracellular matrix of gingival tissues by producing a large amount of PA in response to LPS.
The structure and function of the cemento—dentinal junction in human teeth
Authors: Yamamoto T. , Domon T. , Takahashi S. , Islam H. , Suzuki Ft. , Wakita M.
Published: July 2006

The structure and function of the cemento‐dentinal junction were studied in human molars by light and electron microscopy. The cemento‐dentinal junction was an approximately l‐3‐μm‐thick layer full of proteoglycans with mucopolysaccharides but containing fewer collagen fibrils than the root dentin and cementum. In places, cemental fibrils crossed the cemento‐dentinal junction. These fibrils appeared to intermingle with dentinal fibrils. By enzymatic treatment of decalcified specimen with hyaluronidase and trypsin, the cemento‐dentinal junction decreased or lost staining affinity to toluidine blue. Prolonged treatment caused the separation of cementum from the root dentin during routine histological processes. These data suggest that the adhesion of proteoglycans is more important than the intermingling of dentinal and cemental fibrils for the cemento‐dentinal attachment.
Multiple forms of the major phenylalanine specific protease in Treponema denticola
Authors: Rosen Graciela , Naor Ronit , Sela Michael N.
Published: July 2006

The 160, 190 and 270 kDa outer sheath proteases of Treponema denticola ATCC 35404 were found to be multiple forms of the major 91 kDa phenylalanine protease (PAP) by immunoblotting using anti‐91kDa specific antibodies. Multiple forms of the phenylalanine protease were also found in 2 other T. denticola strains studied, ATCC 33520 and the clinical isolate GM‐1. Protein, proteolytic and Western blot analyses using antibodies against the PAP and the major outer sheath protein (MSP) indicated that the 190 and 270 kDa proteases were protein complexes formed by the MSP and the PAP. These complexes dissociated by storage in 0.3% or higher SDS concentrations. The purified PAP was found to completely degrade keratin, but was unable to degrade native actin either in its monomeric or polymerized form. The association of the MSP adhesin with a protease capable of degrading host native proteins may benefit the obtention of protein‐based nutrients necessary to support the growth of these treponemes. These complexes may also play a role in the structural organization of T. denticola outer sheath.
Quantitative comparison of cytocidal effects of tetracyclines and fluoroquinolones on human periodontal ligament fibroblasts
Authors: Omori Nobuhiko , Kobayashi Haruo , Tsutsui Takeki
Published: July 2006

The cytocidal effects of tetracyclines and fluoroquinolones on human periodontal ligament fibroblasts (Pel cells) were studied. Pel cells were treated for 24 h with tetracycfine (TC), demeclocychne (DMC), minocycline (MINO), chlortetracycline (CTC), tosufloxacin (TFLX), enoxacin (ENX), sparfloxacin (SPFX), lomefloxacin (LFLX) or ofloxacin (OFLX), and allowed to form colonies. The cytocidal effects of the antibacterial agents, as determined by a decrease in colony‐forming efficiency, increased as the dose increased. However, CTC was an exception. As a quantitative measure of the cytocidal effect, LD50, the concentration which results in a 50% decrease in colony‐forming efficiency relative to control cells, was extrapolated from the dose‐response curves. The rank‐order of cytocidal effects (LD) was DMC ∼ MINO ∼ TC ≫ CTC. DMC, MINO and TC were at least 5.6–6.6 times more cytocidal than CTC. The cytocidal effects of the fluoroquinolones were in the following order: TFLX > ENX > SPFX > LFLX > OFLX. TFLX, ENX, SPFX and LFLX were 36.3, 11.4, 7.7 and 3.1 times more cytocidal than OFLX, respectively. Little cytocidal effect was observed when the cells were treated with either ≤ 0.03 mM tetracyclines or ≤ 0.01 mM fluoroquinolones. The results provide useful estimates concerning the relative toxicities against human periodontal ligament of antibacterial agents used to treat periodontitis.
Healing of human intrabony defects following treatment with enamel matrix proteins or guided tissue regeneration
Authors: Sculean A. , Donos N. , Windisch P. , Brecx M. , Gera I. , Reich E. , Karring T.
Published: July 2006

The aim of the present study was to evaluate histologically in humans the healing of advanced intrabony defects following treatment with enamel matrix proteins (EMD) or guided tissue regeneration (GTR). Fourteen patients, each of them displaying 1 advanced intrabony defect around teeth scheduled for extraction were included in the study. The defects were treated randomly either with an enamel matrix protein derivative (Emdogain ®, BIORA AB, Malmö, Sweden) or with a bioabsorbable membrane (Resolut®, Regenerative Material. W.L. Gore & Assoc, Flagstaff, Arizona, USA). At baseline the mean probing pocket depth (PPD) in the EMD group was 11.3 ± 1.8 mm and the mean clinical attachment level (CAL) 12.1 ± 2.0 mm. whereas in the GTR group the mean PPD was 11.4 ± 2.2 mm and the mean CAL 13.3 ± 2.3 mm. Healing was uneventful in all cases. Neither allergic reactions against EMD or the bioabsorbable membrane. nor suppuration or abscesses were observed. The clinical results revealed at 6 months in the EMD group a mean PPD of 5.6 ± 1.3 mm and a mean CAL of 9.1 ± 1.5 mm. In the GTR group the mean PPD was 5.6 ± 1.3 mm and the mean CAL 10.1 ± 1.5 mm. The histological analysis showed in the EMD group a mean 2.6 ± 1.0 mm of new attachment (i.e. new cementum with inserting collagen fibers) and a mean 0.9 ± 1.0 mm of new bone. In this group, the formation of new attachment was not always followed by bone regeneration. In the GTR group, the mean new attachment was 2.4 ± 1.0 mm and the mean new bone 2.1 ± 1.0 mm. In every case treated with GTR, the formation of new attachment was followed by a varying amount of new bone. After both types of regenerative treatment the newly formed cementum displayed a predominantly cellular character. The findings of the present study indicate that the treatment of intrabony defects with enamel matrix proteins or with bioabsorbable membranes enhances the formation of a new connective tissue attachment in humans.
Association of periodontal infections with atherosclerotic and pulmonary diseases
Authors: Scannapieco F. A. , Genco R. J.
Published: July 2006

Chronic infections may influence the severity and/or course of a number of systemic diseases. Periodontal diseases are localized chronic inflammatory conditions of the gingiva and underlying bone and connective tissues induced by bacteria and bacterial products of dental plaque. This paper will discuss the evidence for the role of periodontal disease in the pathogenesis of 2 important systemic diseases, atherosclerosis and pulmonary infections. Both epidemiological and laboratory studies are reviewed to assess the biological basis for the association of periodontal infections and these important diseases. Several potential mechanisms by which periodontal diseases may influence these conditions are also discussed.
Periodontitis‐atherosclerosis syndrome: an expanded model of pathogenesis
Authors: Offenbacher Steven , Madianos Phoebus N. , Champagne Catherine M. E. , Southerland Janet H. , Paquette David W. , Williams Ray C. , Slade Gary , Beck James D.
Published: July 2006

The early reports of a linkage between periodontitis and atherosclerosis have garnered further support by additional data generated by several investigative teams in many different countries. The evidence continues to suggest that periodontitis may be an important risk factor or risk indicator for cardiovascular pathology for some individuals. The term periodontitis‐atherosclerosis syndrome (PAS) is proposed as a new diagnostic term to describe this condition in these individuals. Current evidence, albeit preliminary in nature, which describes a cluster of clinical signs and symptoms that are associated with this condition, is presented. It is clear that this syndrome will require considerable study and refinement before a definitive diagnosis and treatment plan can be formulated. Potential mechanisms by which systemic inflammation and infectious challenge of periodontal origin may serve as a potential modifier of cardiovascular disease are discussed in the context of a detailed working model of pathogenesis. This hypothetical model embraces many cellular and molecular components of atherogenesis and thromboembolic diseases from the perspective of periodontitis pathogenesis. Many aspects of the hypothetical model remain unproved; however, it is our opinion that only through the clarification of the mechanisms of pathogenesis can we ultimately construct a knowledge framework for accurate diagnoses and successful therapies. The concept of diagnosing and treating a periodontal patient to minimize the deleterious effects of this chronic infectious and inflammatory condition on the cardiovascular system represents an unprecedented challenge to our profession.
Lipoxin A4 and aspirin‐triggered 15‐epi‐LXA4 inhibit tumor necrosis factor‐α‐initiated neutrophil responses and trafficking: novel regulators of a cytokine—chemokine axis relevant to periodontal diseases
Authors: Pouliot Marc , Serhan Charles N.
Published: July 2006

The impact of lipoxin A4 (LXA4) and aspirin‐triggered‐lipoxins (ATL) was investigated in tumor necrosis factor (TNFα)‐initiated neutrophil (PMN) responses in vitro and in vivo using LX analogs that are metabolically more stable. At nanoraolar levels, the LXA4 and ATL analog 15 R/S‐methyl‐LXA4 each blocked TNFa‐stimulated IL‐1β release by isolated human PMN in vitro. These LXA4‐ATL actions were time‐ and concentration‐dependent. The TNFα‐induced IL‐1β gene expression was also regulated by 15 R/S‐methyl‐LXA4. In addition, 15 R/S‐methyl‐LXA4 added to murine air pouches dramatically inhibited TNFα‐stimulated leukocyte trafficking in vivo, as well as altered the appearance of both macrophage inflammatory peptide‐2 and IL‐1 ji and concomitantly stimulated IL‐4 in pouch exudates. These findings from in vitro and in vivo experiments indicate that both LXA4 and ATL are regulators of TNFα‐directed neutrophil actions and stimulate IL‐4 in exudates and thus regulate mediators that are held to play an important role in the pathogenesis of periodontal disease.
HLA genetics for diagnosis of susceptibility to early‐onset periodontitis
Authors: Takashiba Shogo , Ohyama Hideki , Oyaizu Kosuke , Kogoe‐Kato Nahoko , Murayama Yoji
Published: July 2006

Human leukocyte antigens (HLA) are essential in the recognition of foreign antigens in humoral immune response, which is genetically predetermined. Susceptibility to certain diseases that involve the immune response has been studied in relation to distinct HLA types. Although some diseases have been found to correlate to specific HLA loci positively, it has been difficult to isolate HLA types that predispose patients to periodontal destruction. Here, we review the current knowledge and recent advances in HLA genetics and its biology, which determine susceptibility to early‐onset periodontitis (EOP). The HLA‐DRB1*1501‐DQB1*0602 genotype has been found with increasing frequency in EOP patients. This HLA genotype expresses aspartic acid at position 57 and glycine at position 70 on the DQβ chain, suggesting a capability to bind certain bacterial antigens. The T cell response against the outer membrane protein (Ag53) of Porphyromonas gingivalis was examined via this HLA genotype. Strong T cell response against Ag53 p 141‐161 was inhibited partially by anti‐DR antibody, but not by anti‐DQ antibody. Possible host and bacterial peptides capable of binding DRBI * 1501 were elucidated when the peptide sequence was compared to gene and protein databases. These results suggest that patients who have the HLA‐DRB1* 1501‐DQB 1*0602 genotype may have an accelerated T cell response to certain periodontopathic bacteria such as P. gingivalis in hyperimmune reactions and thus increased susceptibility to EOP.
Analysis of genetic polymorphisms at the interleukin‐10 and tumour necrosis factor loci in early‐onset periodontitis
Authors: Kinane D. F. , Hodge P. , Eskdale J. , Ellis R. , Gallagher G.
Published: July 2006

Early onset periodontitis (EOP) is considered to have a substantial genetic basis, although the gene or genes involved have not been elucidated. The aim of the present study was to investigate possible links between generalized EOP (GEOP) and genes regulating expression of the cytokines tumour necrosis factor (TNF) and interleukin‐10 (IL‐10). Microsatellite marker DNA sequences corresponding to phenotypic variations in cytokine response were analysed. Genotypic variations in cytokine response have been shown in vitro for TNF and IL‐10. and specific alleles are implicated in diseases such as systemic lupus erythmatosus (SLE) and rheumatoid arthritis (RA). Two microsatellites at the IL‐10 locus, IL10.R and IL10.G, and 1 microsatellite at the TNF locus, TNFa, were typed for 77 GEOP patients in the West of Scotland. Due to the highly polymorphic nature of the microsatellite loci, a statistical comparison with ethnically matched healthy controls (TNFa, n= 91, tLI O.R. n= 94, IL10.G. n= 102) was conducted using a Monte Carlo simulation for each marker. No significant differences were observed for any of the 3 markers, although there were possible indications of trends similar to those observed in SLE for the IL10.G marker. In conclusion, no links were found between GEOP and microsatellites at TNFa, IL10.R or IL10.G loci.
Porphyromonas gingivalis virulence factors and invasion of cells of the cardiovascular system
Authors: Progulske‐Fox Ann , Kozarov Emil , Dorn Brian , Jr William Dunn , Burks Jacob , Wu Yi
Published: July 2006

Our laboratory is interested in the genes and gene products involved in the interactions between Porphyromonas gingivalis (Pg) and the host. These interactions may occur in either the periodontal tissues or other non‐oral host tissues such as those of the cardiovascular system. We have previously reported the cloning of several genes encoding hemagglutinins, surface proteins that interact with the host tissues, and are investigating their roles in the disease process. Primary among these is HagA, a very large protein with multiple functional groups that have significant sequence homology to protease genes of this species. Preliminary evidence indicates that an avirulent Salmonella typhimurium strain containing hagA is virulent in mice. These data indicate that HagA may be a key virulence factor of Pg, Additionally, we are investigating the invasion of primary human coronary artery endothelial cells (HCAEC) by Pg because of the recent epidemiological studies indicating a correlation between periodontal disease (PD) and coronary heart disease (CHD). We found that some, but not all, strains of Pg are able to invade these cells. Scanning electron microsopy of the infected HCAEC demonstrated that the invading organisms initially attached to the host cell surface as aggregates and by a “pedestal”‐like structure. By transmission electronmicroscopy it could be seen that internalized bacteria were present within multimembranous compartments localized with rough endoplasmic reticulum. In addition, invasion of the HCAEC by Pg resulted in an increase in the degradation of long‐lived cellular proteins. These data indicate that Pg are present within autophagosomes and may use components of the autophagic pathway as a means to survive intracellularly. However, Pg presence within autophagosomes in KB cells could not oe observed or detected. It is therefore likely that Pg uses different invasive mechanisms for different host cells. This and the role of HagA in invasion is currently being investigated further.
The rag locus of Porphyromonas gingivalis: a novel pathogenicity island
Authors: Curtis M. A. , Hanley S. A. , Aduse‐Opoku J.
Published: July 2006

Previous studies in our laboratories of the serum IgG antibody response of periodontal patients have demonstrated the presence of an immunodominant surface antigen (Mr 55 kDa) in the outer membrane of Porphyromonas gingivalis W50. Genetic analysis of this antigen revealed that the corresponding gene forms part of a small operon which may have arisen via horizontal gene transfer into the genome of this strain. On the basis of sequence homology, the 55 kDa antigen (RagB) and the product of a cotranscribed gene (RagA) may act in concert at the surface of the bacterium to facilitate active transport, mediated through the periplasmic spanning protein, TonB, or form part of a signal transduction system in this organism. The rag locus is present in only a proportion of P. gingivalis laboratory strains and clinical isolates. Analysis of the distribution of ragB in subgingival samples by PCR demonstrated that rag+ P. gingivalis are more frequently detected in deep periodontal pockets than shallow sites in periodontal patients. These findings indicate that the rag genes may influence the virulence potential of P. gingivalis strains which harbour this locus and may thus be considered a novel pathogenicity island. Furthermore, horizontal gene transfer between organisms in subgingival plaque may represent a significant force in the evolution of these bacteria with ramifications for both diagnosis and targeted treatment of periodontal disease.
Evolution of periodontal regeneration: from the roots’ point of view
Authors: Somerman M. J. , Ouyang H. J. , Berry J. E. , Saygin N. E. , Strayhorn C. L. , D'Errico J. A. , Hullinger T. , Giannobile W. V.
Published: July 2006

Tissues lost as a consequence of periodontal diseases, i.e. bone, cementum and a functional periodontal ligament (PDL), can be restored to some degree. Nevertheless, results are often disappointing. There is a need to develop new paradigms for regenerating periodontal tissues that are based on an understanding of the cellular and molecular mechanisms regulating the development and regeneration of periodontal tissues. As one approach we have developed strategies for maintaining cementoblasts in culture by first determining the gene profile for these cells in situ. Next, cells were immortalized in vitro using SV 40 large T antigen (SV40 Tag) or by using mice containing transgenes enabling cellular immortality in vitro. Cementoblasts in vitro retained expression of genes associated with mineralized tissues, bone sialoprotein and osteocalcin, that were not linked with periodontal fibroblasts either in situ or in vitro. Further, cementoblasts promoted mineralization in vitro as measured by von Kossa and in vivo using a severely compromised immunodeficient (SCID) mouse model. These cells responded to growth factors by eliciting changes in gene profile and mitogenesis and to osteotropic hormones by evoking changes in gene profile and ability to induce mineral nodule formation in vitro. The ultimate goal of these studies is to provide the knowledge base required for designing improved modalities for use in periodontal regenerative therapies.
Cysteine protease inhibitory activity and levels of salivary cystatins in whole saliva of periodontally diseased patients
Authors: Baron A. C. , Gansky S. A. , Ryder M. I. , Featherstone J. D. B.
Published: July 2006

The 3 human salivary cystatins S, SA and SN are multifunctional proteins that possess a cysteine protease inhibitory property, but their ability to act as such is very different (SN > SA ≫ S). One form, S, also appears to possess antibacterial properties towards the bacterium Porphyromonas gingivalis, often associated with periodontal diseases. In this study we measured the total cystatin inhibitory activity and the levels of each salivary cystatin in the whole saliva of 8 periodontally diseased patients and 2 groups of control subjects (n= 6 and n= 10). The total cystatin inhibitory activity and the total salivary cystatin concentration in the periodontally diseased patients were found to be lower than the controls (p≤ 0.005). The concentration of S was depleted to levels that would not allow it to be an effective antibacterial agent, and the concentration of SA, although depleted in some cases, was still present at sufficient levels to allow it to act as an effective physiological inhibitor of cathepsin L. The concentration of cystatin SN was also depleted in the periodontally diseased patients, but was still present in sufficient quantities to act as an effective physiological cysteine protease inhibitor of cathepsins H and L. In comparison, the concentration of all 3 salivary cystatins in the control subjects were sufficient to enable these proteins to be both effective physiological cysteine protease inhibitors and antibacterial agents.
Prostaglandin E2 receptors of the EP2 and EP4 subtypes downregulate tumor necrosis factor α‐induced intercellular adhesion molecule‐1 expression in human gingival fibroblasts
Authors: Noguchi Kazuyuki , Iwasaki Kengo , Shitashige Miki , Ishikawa Isao
Published: July 2006

Prostaglandin E2 (PGE2) exerts its biological actions via EP receptors, which are divided into 4 subtypes of EP1, EP2, EP3 and EP4. In the present study, we investigated whether PGE2 regulated intercellular adhesion molecule‐1 (ICAM‐1) expression in human gingival fibroblasts (HGF) stimulated with tumor necrosis factor‐α (TNFα) and if so, which subtype(s) of PGE2 receptors was involved. Exogenous addition of PGE2 to HGF inhibited ICAM‐1 expression elicited by TNFα in a concentration‐dependent manner. Treatment of HGF with indomethacin, a cyclo‐oxygenase inhibitor, had no effect on TNFα‐elicited ICAM‐1 expression, although indomethacin completely inhibited PGE2 production enhanced by TNFα. Next, we examined which subtype(s) of the 4 EP receptors modulated the ICAM‐1 expression elicited by TNFα, using subtype‐specific agonists and antagonists. 11‐deoxy‐PGE1, a selective EP2/EP4 agonist, inhibited TNFα‐elicited ICAM‐1 expression as potently as PGE2, while butaprost, a selective EP2 agonist, was somewhat less effective than PGE2. AH23848B, an EP4 antagonist, antagonized the inhibitory effect of TNFα‐elicited ICAM‐1 expression by PGE2. Sulprostone, an EP1/EP3 agonist, and ONO‐AP‐324, an EP3 agonist, were inert to TNFα‐elicited ICAM‐1 expression. As EP2 and EP4 receptors are linked to elevation of intracellular cyclic AMP (cAMP), the effect of dibutyryl cAMP and 8‐bromo‐cAMP, cAMP analogs, on TNFα‐elicited ICAM‐1 expression was examined. Both the agents downregulated ICAM‐1 expression in TNFα‐stimulated HGF. From these data, we suggest that PGE2 downregulates TNFα‐induced ICAM‐1 expression in HGF, via EP2 and EP4 receptors by cAMP‐dependent signaling pathways, which may result in control of inflammatory and immunological responses in periodontal disease.
Bird Pollination of Explosive Flowers While Foraging for Nectar and Caterpillars1
Authors: Agostini Kayna , Sazima Marlies , Sazima Ivan
Published: July 2006

Mucuna (Fabaceae) has explosive flowers that open only if a pressure is applied on their wings and keel. The cacique Cacicus haemorrhous inserts its bill into a flower and spreading its mandibles apart it opens the flower to take nectar. This icterine bird also preys upon caterpillars of the butterfly Astraptes talus that pupates within the flowers. Foraging with use of bill movements to take nectar or insects within a flower is an adequate mechanism to open and pollinate explosive flowers. We suggest that a plausible behavioral scenario for the pollination relationship between icterines and Mucuna‐like flowers might start with the birds' searching for insects within flowers.
Coupling of Alkylarene and Pentamethyl[60]fullerene by Iridium-catalyzed Benzylic C–H Bond Activation
Authors: Matsuo Yutaka , Iwashita Akihiko , Nakamura Eiichi
Published: July 2006

Heating of C60Me5Br in toluene in the presence of an iridium catalyst and triethylamine results in benzylation of the fullerene core to yield C60Me5CH2C6H5. The reaction is general for various alkylarenes, and probably takes place via iridium-catalyzed activation of a benzylic C–H bond.
Cyclic Diaminocarbene–Rhodium(I) Complex Tethered to Disulfide: Synthesis and Application to Gold Surface Modification
Authors: Hara Kenji , Iwahashi Keiji , Kanamori Yoshikazu , Naito Satoshi , Takakusagi Satoru , Uosaki Kohei , Sawamura Masaya
Published: July 2006

A dimeric N-heterocyclic carbene (NHC)–rhodium(I) complex connected with a long chain dialkyl disulfide linker was synthesized, and used for the preparation of a Rh-modified alkane thiolate monolayer on a gold surface.
Highly-dispersed and Size-controlled Ruthenium Nanoparticles on Carbon Nanofibers: Preparation, Characterization, and Catalysis
Authors: Motoyama Yukihiro , Takasaki Mikihiro , Higashi Kenji , Yoon Seong-Ho , Mochida Isao , Nagashima Hideo
Published: July 2006

Facile synthesis of ruthenium nanoparticles supported on the carbon nanofibers (CNFs) is accomplished by thermal decomposition of Ru3(CO)12; ruthenium species on the platelet-type CNF are dispersed homogeneously and selectively on the edge of the graphite layers with narrow size distributions and behaves as an excellent catalyst for arene hydrogenation.
Ti–Si Mixed Oxides by Non-hydrolytic Sol–Gel Synthesis as Potential Gold Catalyst Supports for Gas-phase Epoxidation of Propylene in H2 and O2
Authors: Dai Maohua , Tang Dingliang , Lin Zhijie , Yang Hongwei , Yuan Youzhu
Published: July 2006

The amorphous Ti–Si mixed oxides prepared from chloride precursors using a one-step nonhydrolytic sol–gel route could serve as efficient gold catalyst supports for gas-phase epoxidation of propylene in O2 and H2. A propylene conversion of 6.8% at the initial 60 min and 4.0% after 4 h of time-on-steam, keeping a selectivity to propylene oxide as high as 95%, was obtained over the gold supported on a Ti–Si mixed oxide containing 10 mol % of Ti.
Incorporation of Dyes into Silica–Surfactant Mesostructured Nanoparticles as a Nanoscale Host Material for Organic Molecules
Authors: Muto Shigeyuki , Oaki Yuya , Imai Hiroaki
Published: July 2006

Various kinds of organic dye molecules were successfully incorporated into silica–surfactant nanoparticles with a hexagonally ordered mesostructure. The dye-incorporated composite particles, which had a diameter of ca. 30 nm, exhibited specific fluorescent properties and pH sensitivity derived from the organic molecules.
Lattice Vibration Fundamentals of Anatase Nanocrystalline TiO2 Thin Films Detected Using Unpolarized Infrared Spectroscopy
Authors: Wang Deliang , Zhang Xinyu , Wu Kunjie , Xu Shuhua
Published: July 2006

Unpolarized infrared spectroscopic study was carried out on thin nanocrystalline anatase TiO2 films with grain size of ≈20 nm. The transverse optical lattice vibration frequencies are the same as that of single-crystal anatase. The longitudinal optical modes can be detected with an oblique unpolariation at incident angles ≥50°. The broad LO absorption peak is a combination of the A2u LO and the Eu LO modes’ resonant response to the infrared radiation.
Structural and Electrochemical Properties of Li[Cr0.29Li0.24Mn0.47]O2 Nanocomposite Electrode for Lithium-ion Batteries
Authors: Park Chan-Woo , Kim Jaekook
Published: July 2006

Li[Cr0.290Li0.240Mn0.470]O2 with nanocomposite structures was synthesized by a solution method with subsequent quenching. The crystalline structure was investigated by X-ray diffraction (Rietveld refinement), electron diffraction, and HRTEM. According to coindexed electron diffraction patterns and HRTEM images, Li[Cr0.290Li0.240Mn0.470]O2 was found to be nanocomposite powders indexed in monoclinic and hexagonal structures. The nanocomposite cathode prevented spinel-like structural transformation during cycling and delivered a good reversible capacity of about 195 mA h/g.
Gene Conversion Between Direct Noncoding Repeats Promotes Genetic and Phenotypic Diversity at a Regulatory Locus of Zea mays (L.)
Authors: Zhang Feng , Peterson Thomas
Published: July 2006

While evolution of coding sequences has been intensively studied, diversification of noncoding regulatory regions remains poorly understood. In this study, we investigated the molecular evolution of an enhancer region located 5 kb upstream of the transcription start site of the maize pericarp color1 (p1) gene. The p1 gene encodes an R2R3 Myb-like transcription factor that regulates the flavonoid biosynthetic pathway in maize floral organs. Distinct p1 alleles exhibit organ-specific expression patterns on kernel pericarp and cob glumes. A cob glume-specific regulatory region has been identified in the distal enhancer. Further characterization of 6 single-copy p1 alleles, including P1-rr (red pericarp/red cob) and P1-rw (red pericarp and white cob), reveals 3 distinct enhancer types. Sequence variations in the enhancer are correlated with the p1 gene expression patterns in cob glume. Structural comparisons and phylogenetic analyses suggest that evolution of the enhancer region is likely driven by gene conversion between long direct noncoding repeats (∼6 kb in length). Given that tandem and segmental duplications are common in both animal and plant genomes, our studies suggest that recombination between noncoding duplicated sequences could play an important role in creating genetic and phenotypic variations.
Reconstructing the Evolutionary History of Paralogous APETALA1/FRUITFULL-Like Genes in Grasses (Poaceae)
Authors: Preston Jill C , Kellogg Elizabeth A
Published: July 2006

Gene duplication is an important mechanism for the generation of evolutionary novelty. Paralogous genes that are not silenced may evolve new functions (neofunctionalization) that will alter the developmental outcome of preexisting genetic pathways, partition ancestral functions (subfunctionalization) into divergent developmental modules, or function redundantly. Functional divergence can occur by changes in the spatio-temporal patterns of gene expression and/or by changes in the activities of their protein products. We reconstructed the evolutionary history of two paralogous monocot MADS-box transcription factors, FUL1 and FUL2, and determined the evolution of sequence and gene expression in grass AP1/FUL-like genes. Monocot AP1/FUL-like genes duplicated at the base of Poaceae and codon substitutions occurred under relaxed selection mostly along the branch leading to FUL2. Following the duplication, FUL1 was apparently lost from early diverging taxa, a pattern consistent with major changes in grass floral morphology. Overlapping gene expression patterns in leaves and spikelets indicate that FUL1 and FUL2 probably share some redundant functions, but that FUL2 may have become temporally restricted under partial subfunctionalization to particular stages of floret development. These data have allowed us to reconstruct the history of AP1/FUL-like genes in Poaceae and to hypothesize a role for this gene duplication in the evolution of the grass spikelet.
Genetic Exchange Between Homeologous Sequences in Mammalian Chromosomes Is Averted by Local Homology Requirements for Initiation and Resolution of Recombination
Authors: Yang Derek , Goldsmith Edie B , Lin Yunfu , Waldman Barbara Criscuolo , Kaza Vimala , Waldman Alan S
Published: July 2006

We examined the mechanism by which recombination between imperfectly matched sequences (homeologous recombination) is suppressed in mammalian chromosomes. DNA substrates were constructed, each containing a thymidine kinase (tk) gene disrupted by insertion of an XhoI linker and referred to as a “recipient” gene. Each substrate also contained one of several “donor” tk sequences that could potentially correct the recipient gene via recombination. Each donor sequence either was perfectly homologous to the recipient gene or contained homeologous sequence sharing only 80% identity with the recipient gene. Mouse Ltk− fibroblasts were stably transfected with the various substrates and tk+ segregants produced via intrachromosomal recombination were recovered. We observed exclusion of homeologous sequence from gene conversion tracts when homeologous sequence was positioned adjacent to homologous sequence in the donor but not when homeologous sequence was surrounded by homology in the donor. Our results support a model in which homeologous recombination in mammalian chromosomes is suppressed by a nondestructive dismantling of mismatched heteroduplex DNA (hDNA) intermediates. We suggest that mammalian cells do not dismantle mismatched hDNA by responding to mismatches in hDNA per se but rather rejection of mismatched hDNA appears to be driven by a requirement for localized homology for resolution of recombination.