bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Lung Inflation on Levator Veli Palatini Muscle Activity
Authors: Koizumi H. , Kogo M. , Matsuya T. 
Published: January 2009

Palatal movements play a critical role in regulating oropharyngeal airflow during breathing. We hypothesized that these movements are coordinated with breathing movements via afferent signals from the lung. However, the control of palatal movements in relation to the lung remains unclear. This study was designed to define, by electromyographic techniques, the relationship between palatal movement and lung action during respiration. We performed tracheotomies on 12 mongrel dogs anesthetized with sodium pentobarbital and found that lung inflation augmented the activity of the levator veli palatini muscle (LVP). Two kinds of discharges were recognized during the expiratory pause following lung inflation. One was a continuous, low-amplitude discharge induced during apnea following lung inflation. The other was a transient, high-amplitude discharge which appeared immediately after lung inflation. Both of these response activities were eliminated by bilateral vagotomy. We thus concluded that palatal movements, which can regulate expiratory airflow resistance and cause switching from nasal to oral airflow, are under the control of vagal afferent signals from the lung.
Comparative Study of the Chemotactic Responses of Periodontal Ligament Cells and Gingival Fibroblasts to Polypeptide Growth Factors
Authors: Nishimura F. , Terranova V.P. 
Published: January 2009

Selective recruitment of periodontal ligament cells to a previously exposed root surface is believed to enhance periodontal regeneration. It has been hypothesized that competition from gingival fibroblasts may reduce the potential of periodontal regeneration. We compared the migratory responses of PDL cells and gingival fibroblasts to a variety of biologicals. Parallel experiments designed to examine the directed migration responses of both periodontal ligament cells (PDL cells) and gingival fibroblasts (GF) isolated from the same donors were conducted using Platelet Derived Growth Factor (PDGF), Insulin Like Growth Factor-I, -II (IGF-I, -II), Epidermal Growth Factor (EGF), Transforming Growth Factor-β (TGF-β), and the chemotactic factor derived from the conditioned culture media of PDL cells (termed PDL-CTX) as attractants. Both PDL cells and GF exhibited dose-dependent migratory responses when challenged with PDGF, IGF-I, IGF-II, EGF, and TGF-β. However, when these cells were challenged with PDL-CTX, only PDL cells migrated in a specific dose-dependent manner, while GF were refractive to PDL-CTX stimulation. Additionally, concentrated conditioned culture media from cultures of gingival fibroblasts did not stimulate PDL cell migratory responses. In other experiments, antibody directed against PDGF, FGF, TGF-β, IGF-I, IGF-II, NGF, and EGF did not inhibit the PDL-CTX-elicited response in PDL cells. Previous studies have suggested that success of periodontal therapy depends on the specific attachment, migration, and proliferation of selected periodontal ligament cells. The data presented in this manuscript suggest that both PDL cells and gingival fibroblasts respond to a multitude of growth factors. PDL-CTX was found to be PDL-cell-specific for directed migration. Thus, we conclude that any biological therapeutic regime for periodontal regeneration should include PDL-cell-specific agents.
Expression of Adhesion Molecules during Tooth Resorption in Feline Teeth: A Model System for Aggressive Osteoclastic Activity
Authors: Shigeyama Y. , Grove T.K. , Strayhorn C. , Somerman M.J. 
Published: January 2009

Tooth resorption, a common feline dental problem, is often initiated at the cemento-enamel junction and hence is called cat 'neck' lesion. Studies have demonstrated that osteoclasts/odontoclasts are increased and activated at resorption sites, and that areas of resorption are partly repaired by formation of tissues resembling bone, cementum, and possibly dentin. However, the cellular/molecular mechanisms/factors involved in resorption and repair are unknown. In this study of tissues from cats with 'neck' lesions, we used specific antibodies and immunohistochemical analyses to examine adhesion molecules associated with mineralized tissues, bone sialoprotein (BSP) and osteopontin (OPN), and a cell-surface receptor linked with these molecules, α vβ3, for their localization in these lesions. In addition, to determine general cellular activity during repair, we performed in situ hybridization using a type I collagen riboprobe. Results showed OPN localized to resorption fronts and reversal lines, while BSP was localized to reversal lines. However, some osteoclasts and odontoblasts "sat" on mineralized surfaces not associated with OPN. The cell-surface receptor, αvβ 3, was localized to surfaces of osteoclasts/odontoclasts. Type I collagen mRNA was expressed where osteoblasts attempted to repair mineralized tissue. In contrast, odontoblasts did not express mRNA for type I collagen. This study suggests that osteoclastic resorption is the predominant activity in 'neck' lesions and that this activity was accompanied, at least in part, by increased concentrations of OPN and an associated integrin, α vβ3, at resorption sites. Lack of collagen expression by odontoblasts indicates that odontoblasts do not play an active role in attempts at repair.
Salt Fluoridation and General Health
Authors: Bergmann K.E. , Bergmann R.L. 
Published: January 2009

Salt fluoridation is a systemic form of fluoride supplementation, leaving it to the consumer whether he wants fluoride supplements or not, but thereafter not requiring special dependability for daily compliance. Most German drinking water has low fluoride concentrations. The estimated fluoride intake in German children is between 100 and 300 μg/day, and in adults, between 400 and 600 μg/day. Male subjects have higher mean intakes than females. From 70 to 90% of the salt intake of 10 to 13.5 g/day in German adults comes from commercially prepared foods. This leaves about 1 to 4 g of salt to be added as table salt at the individual level and to become the source of supplementary fluoride. To increase fluoride intake by at least 500 μg/d, and to prevent an additional intake of more than 3000 μg/day, it may be necessary to have salt at a fluoride level of around 500 μg/g or to include one commercial food to be prepared with fluoridated salt, e.g., bread. A salt fluoride concentration of 250 μg/g does not present a risk of dental fluorosis. However, clear recommendations about systemic fluoride supplementation must be given as long as there are fluoride tablets, fluoride-rich mineral waters, and fluoridated table salt available simultaneously. Persons at risk for hypertension from salt consumption require different means of fluoride supplementation. By and large, in areas of low drinking water fluoride, fluoridated table salt has the potential to become a means of systemic supplementation comparable with drinking water fluoridation.
Animal Caries Models: Reaction Paper
Authors: Mundorff-Shrestha S.A. 
Published: January 2009

All caries models, including animal models, must demonstrate validity, which is the ability to assess the caries process as it relates to humans. One aspect in assessing validity is the establishment of fluoride dose response. A review of the literature regarding dose response from topical fluorides in rat caries models has indicated that validity has already been shown for fluoride in dentifrices and for fluoride in food and water. Therefore, investing future time and effort in the rat caries model is justified and warranted. Specific areas to be addressed include: performance of thorough literature searches and data analysis, standardization of the model, synchronization of caries measurements, development of a summary "caries value", determination of a human caries "equivalence factor", and determination of best treatment conditions.
Role of Saliva in Caries Models
Authors: Edgar W.M. , Higham S.M. 
Published: January 2009

The crucial role played by the actions of saliva in controlling the equilibrium between de- and remineralization in a cariogenic environment is demonstrated by the effects on caries incidence of salivary dysfunction and by the distribution of sites of caries predilection to those where salivary effects are restricted. However, of the several properties of saliva which may confer protective effects, it is not certain which are most important. A distinction can be made between static protective effects, which act continuously, and dynamic effects, which act during the time-course of the Stephan curve. Evidence implicates salivary buffering and sugar clearance as important dynamic effects of saliva to prevent demineralization; of these, the buffering of plaque acids may predominate. Enhanced remineralization of white spot lesions may also be regarded as dynamic protective effects of saliva. Fluoride in saliva (from dentifrices, ingesta, etc.) may promote remineralization and (especially fluoride in plaque) inhibit demineralization. The design of experiments using caries models must take into account the static and dynamic effects of saliva. Some models admit a full expression of these effects, while others may exclude them, restricting the range of investigations possible. The possibility is raised that protective effects of saliva and therapeutic agents may act cooperatively.
Deposit Formation on Prosthetic Materials in Vivo After One Year: a Quantitative Study of Twelve Materials
Authors: Zanghellini G. , Dykman A.G. , Rheinberger V. , Arends J. 
Published: January 2009

In vivo-formed deposits on prosthetic materials are of considerable interest. Deposit quantification is important to gain insight into the mechanisms of formation and removal. A new method is presented for the quantitative investigation of deposit formation in vivo on 12 experimental materials after one year. The parameter assessed is the deposition parameter, D, the fraction of the surface covered by deposits. The materials were arranged in a given sequence in the prosthesis flanges and carried in two investigations by 11 and 20 participants for one year. The results show that the parameter D is strongly material-, participant-, and site-dependent. Differences between materials varied by a factor of at least 25; PMMA (Polymethylmethacrylate) was always lowest in D value. The D values in the upper prosthesis were always larger than in the lower prosthesis; the ratio Dupper /D lower was 2.3 ± 0.5. The material parameters strongly influencing the deposit formation were of both the monomer and the filler type. Attempts were made to correlate D with surface hardness, surface roughness, and water absorption. Only the last parameter was clearly linearly related to D. LASMA (Laser Mass Spectrometry) studies showed that the chemical nature of the deposits formed in vivo on prosthetic materials is. in general, initially different from that of calculus.
Stain and Subsurface Degradation of Dental Composites as a Function of Structure and Permeability: a Clinical and Laboratory Study
Authors: Mair L.H. 
Published: January 2009

Staining and subsurface degradation of dental composites were studied in a clinical trial and associated laboratory experiments. The materials in the clinical trial were Clearfil Posterior, Occlusin, and P-30. A significantly higher proportion of Occlusin restorations exhibited marginal stain. An in vitro study indicated that the clinical practice of curing the unfilled bonding resin prior to placing the composite caused the formation of a resin interface with the potential to stain. Bonding resins containing hydrophilic monomers such as HEMA stained more than resins based on BIS-GMA/TEGDMA. In restorations which had been removed for replacement, P-30 exhibited a significantly higher depth of subsurface degradation as assessed by silver nitrate staining. In vitro studies indicated that this material was more permeable and leached more inorganic ions than the other materials. It is suggested that, in clinical practice, the thickness of the bonding resin should be kept to a minimum, and that modem materials with soluble glass fillers should be investigated so that the effects of these fillers on permeability and degradation can be observed.
Studies on Dental Stains Induced by Antibacterial Agents and Rational Approaches for Bleaching Dental Stains
Authors: Nathoo S.A. , Gaffar A. 
Published: January 2009

Extrinsic stain resides in the dental pellicle and can be caused by introduction of chromogenic materials or therapeutic agents into the oral cavity. In contrast, intrinsic tooth stain is found within the tooth structure and can be caused by a variety of agents, including hematological and developmental abnormalities and drugs such as tetracycline. The mechanisms of extrinsic stain formation differ with respect to the causative agent. For example, stain induced by chlorhexidine (CH) can be explained by an increased rate in the non-enzymatic browning reactions occurring at the pellicle surface, while food stains are retained on the surface via ion exchange mechanisms. Although most extrinsic dental stain can be removed by abrasive and/or surface-active materials, removal of certain types of surface stain, e.g., staining due to cationic antimicrobial agents, requires specific agents such as aminoguanidine to reduce the stain. A broad-spectrum approach to reduce both intrinsic and extrinsic dental stains clinically requires oxygenating agents. To evaluate this approach and understand the mechanisms of stain removal, we developed a spectroscopic method for measuring stain in vivo. A series of clinical studies was performed to evaluate stain removal by the agents. The results showed that carbamide peroxide in combination with surfactants and anti-redeposition agents, e.g., sodium pyrophosphate, was more effective in bleaching dental stain compared with carbamide peroxide alone. A detailed examination of the tooth structure by microhardness measurements, x-ray photoelectron spectroscopy, and scanning electron microscopy showed that stain decolorization with this system did not have any adverse effects.
Autoimmune Aspects of Pemphigus Vulgaris and Mucosal Pemphigoid
Authors: Sciubba J.J. 
Published: January 2009

Oral mucosal lesions of ulcerative, desquamative, and bullous character are major problems for clinicians and patients alike. Underlying such processes is the autoimmune reaction manifesting as specific subsets of immunopathology. Responsible for the maintenance of mucosal integrity within the oral cavity are numerous adhesion proteins which operate at the cell-to-cell and cell-to-connective-tissue-matrix level. Two of the better-understood conditions characterized by altered or disordered levels of adherence are the pemphigus and the pemphigoid groups of lesions. Autoantibodies in pemphigus vulgaris specifically attack normal proteins within the desmosomal structure. Cellular adhesion is affected by steric interference by antibodies directed against antigens residing within the intercellular space or the desmosome itself. Such alterations ultimately result in cell-to-cell separation, with production of the acantholytic element characteristic of pemphigus vulgaris. Mucous membrane pemphigoid is characterized by a separation at the junction of the epithelium and connective tissue at the level of the basement membrane complex. Histologically, a split occurs in the sub-basilar region, with antibodies directed to the 230-kDa protein component of the hemidesmosome. Minor antigens residing within the basement membrane area include a 180-kDa element as well as other less commonly found proteins near the membrane complex. Manifestations of these illnesses are often severe. Management strategies of pemphigus vulgaris have changed over the recent past, with new modalities supplementing the traditional corticosteroid approach. Both conditions are usually lifelong, with the implications of management a major consideration.
Comparative HPLC, SDS-PAGE, and Immunoblot Analyses of Dental Enamel Proteins
Authors: Ryu O.H. , Hu C.-C. , Simmer J.P. 
Published: January 2009

The primary structures of amelogenins expressed from different genes vary because of DNA sequence divergence and variations in alternative RNA splicing. The pattern of splicing is unique for each amelogenin gene yet investigated, even when two copies of the gene are expressed in the same cell. Despite the high conservation of amelogenin sequences, diversity in the pattern of RNA splicing leads to significant differences in the number and character of amelogenin isoforms in the developing enamel matrix. Since conservation of molecular structure is an indicator of functional significance, we compared enamel protein preparations from rat, porcine, rabbit, and opossum developing tooth organs. Enamel extracts were fractionated by reversed-phase high-performance liquid chromatography (HPLC) and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Western blot analyses were performed with polyclonal antibodies raised against recombinant murine amelogenin and the polypeptide encoded by murine exon 4. The opossum enamel extract produced the simplest chromatogram, suggesting that fewer proteins are secreted into the developing enamel matrix. The predominant opossum amelogenin has an apparent molecular mass of 28 kDa and reacts strongly with the recombinant amelogenin antibody but is not recognized by the murine exon 4 antibody. Opossum amelogenin mRNA was amplified with murine amelogenin primers specific for the amino- and carboxyl-terminal coding regions. The mobility of the amplification products on 4% agarose gels indicates that the leucine-rich amelogenin polypeptide (LRAP) is expressed in the opossum and that the major amelogenin is larger than its homologue in the mouse. We conclude that the alternative splicing of amelogenins pre-dates the metatherian and eutherian divergence over 100 million years ago.
Anion Translocation Through the Enamel Organ
Authors: Prostak K.S. , Skobe Z. 
Published: January 2009

The objective of this study was to determine whether cells of the secretory- and maturation-stage enamel organ of rats contain anion translocation mechanisms similar to those found in other ion-regulating epithelia. Sodium bromide (Br) was used to localize the distribution of anions in the enamel organ. Furosemide, an inhibitor of the Na-K-2C1 co-transporter and other anion transporters, was administered with NaBr or sodium fluoride (F) to investigate if halogens other than Cl can use these transport mechanisms. We obtained the data by using freeze-fracture and freeze-drying methodology in conjunction with scanning and transmission electron microscopy (SEM, TEM) and energy-dispersive x-ray spectroscopy (EDS). The secretory- and maturation-stage enamel organ prevented Br from entering the enamel matrix. Br was localized in the Tomes' processes, but not in the enamel matrix, strongly suggesting that the distal intercellular junctions of ameloblasts are "tight". Furosemide disrupted anion transport to allow not only Cl but also Br to enter the forming enamel matrix. Periodic administration of high F doses promoted the formation of bands of disrupted enamel, reflecting the periodicity of F administration. The same concentration of F administered with furosemide increased the severity of disrupted enamel, resulting in "blisters" and pits in the maturing enamel. The enamel "blisters" contained pools of small, disorganized enamel crystallites. The group receiving furosemide only displayed normal enamel structure but had increased C1 in the enamel matrix. This study provides evidence that anion transporters, possibly the Na-K-2CI co-transporter, function to regulate anion translocation, including F, to the enamel matrix in secretory- and maturation-stage enamel organ. These mechanisms may explain why the ionic composition on the cellular side of the anion barrier is different from that of the enamel matrix.
Properties of Heterogeneous Apatites Containing Magnesium, Fluoride, and Carbonate
Authors: Okazaki M. , Legeros R.Z. 
Published: January 2009

Biological apatites present in the mineral phases of normal and pathological calcifications contain magnesium, Mg, and carbonate, CO3. As a consequence of fluctuations in the composition of the micro-environment, these apatites may sometimes form by heterogeneous precipitation. The purpose of this study was to investigate the properties of (Mg, CO3)-apatites formed heterogeneously in the presence of fluoride, F. Two types of fluoridated (Mg, CO3)-apatites formed from solutions with low and high levels of Mg were prepared at 80°C, pH 7.4. We prepared FMgCO3-MgCO 3AP (Type 1) by adding the F-containing solution to those containing calcium, Mg, and phosphate ions during the first half of the precipitation period. We prepared MgCO3-FMgCO3Ap (Type 2) by adding the F-containing solution during the final half of the period. The apatites were analyzed by x-ray diffraction (XRD), infrared absorption spectroscopy, and scanning electron microscopy (SEM). SEM and XRD analyses showed evidence of mixed crystals in the heterogeneous apatites. The presence of Mg inhibits, while F promotes, apatite crystal growth. In addition, Mg incorporation increased with increasing fluoride concentration. The extent of dissolution in acid buffer of both types of heterogeneous apatites increased with Mg: Type 1 > Type 2. These results suggest that the crystal and dissolution properties of heterogeneous fluoridated (Mg, C03)-apatites are greatly affected by the mode of F incorporation and Mg concentrations in the environment.