bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphological and Functional Characteristics of Acinar Atrophy and Recovery in the Duct-ligated Parotid Gland of the Rat
Authors: Scott J. , Liu P. , Smith P.M.
Published: January 2009

Although acinar atrophy occurs frequently in salivary diseases, the relationship between structural changes and functional decrements is not well-established, and the potential for recovery of histological and functional integrity has not been wholly quantified. We aimed, therefore, to develop further our understanding of pathological acinar atrophy. Stensen's duct was ligated for periods up to six weeks and, in separate experiments, was de-ligated after two weeks and allowed to recover for up to two weeks. Qualitative and quantitative histological analyses were carried out. Additionally, the ability of enzymatically dispersed cells from ligated and de-ligated glands to respond to neuro-hormonal stimuli was also measured. The results confirmed that totally obstructed glands undergo a rapid, progressive severe atrophy amounting to absolute losses of over 85% of acinar tissue by two weeks. Acinar shrinkage and cell losses through apoptosis accounted for the glandular atrophy. Remaining intralobular epithelia consisted of extremely atrophic acini and numerous duct-like structures with intermediate forms. Dispersed cells from atrophic glands exhibited agonist-induced release of chloride similar to normal. Together, these structural-functional results confirm the persistent viability of acinar-like cells in the obstructed gland and suggest that the duct-like structures are derived from surviving atrophic acini. De-ligated glands exhibited a near-normal recovery of structure by two weeks. Their enzymatically dispersed cells responded normally to agonist stimulation. The results support the view that pathological atrophy is largely similar to physiological atrophy, providing a mechanism for acinar cell survival under adverse conditions, with the possibility of eventual recovery.
Morphologic and Biochemical Changes of the Masseter Muscles Induced by Occlusal Wear: Studies in a Rat Model
Authors: Bani D. , Bani T. , Bergamini M.
Published: January 2009

Occlusal alterations may result in changes in the functional performance of masticatory muscles. In this study, we set up an experimental model in rats to examine whether masticatory muscle abnormalities occur after a malocclusion is induced. Rats underwent unilateral amputation of the molar cusps to simulate an occlusal wear situation. The masseter muscles ipsilateral and contralateral to the amputated molars were excised at different experimental times. Sham-operated rats were used as controls. The tissue samples were studied by light and electron microscopy and morphometry. Tissue calcium content, a biochemical index of muscle injury, was also determined. The results show that occlusal dysfunction leads to microvessel constriction and clear-cut morphologic damage of muscular fibers and blood capillary endothelium, as well as to elevation of tissue calcium content, in the ipsilateral masseter muscle. These changes are likely related to muscle fatigue and ischemia. The early signs of injury do not involve the entire muscle but are mostly restricted to tissue areas rich in type I (slow) muscle fibers, which are characterized by a predominantly aerobic metabolism. The muscle damage becomes more extended and severe with time. On the other hand, the contralateral muscles show only slight alterations which are reversible with time, possibly due to an adaptive response.
A Controlled Daytime Challenge of Motor Performance and Vigilance in Sleep Bruxers
Authors: Major M. , Rompre P.H. , Guitard F. , Tenbokum L. , O'Connor K. , Nielsen T. , Lavigne G.J.
Published: January 2009

Many etiological factors have been suggested for sleep bruxism. Among these, elevated mental and physical alertness has been proposed to characterize sleep bruxers. The present study tests the hypothesis that, during the daytime, sleep bruxers are more vigilant and more prone to react to a motor command than are control subjects. Seven sleep bruxers, diagnosed polysomnographically according to validated research criteria, were matched for age and gender to seven control subjects. A simple reaction time task was selected to assess daytime vigilance and motor responsiveness. The following physiological measures were recorded: reaction time, error rate, electroencephalography, electrocardiography, electromyography, and video detection of body movements. Analysis of these variables showed no differences between groups. During the test, bruxers and controls showed a parallel decrease in EEG vigilance and heart rate over time. Frequency of orofacial and body movements was the same in both groups, and no clenching activity was observed during the experimental test. Subjects' visual analog scale ratings revealed that both controls and bruxers were more competitive after the test than before, and bruxers were slightly more anxious than controls before and after the test. Together, the results indicate that sleep bruxers are neither more vigilant nor more prone to react to a motor command during the daytime than are control subjects.
The Diversity and Distribution of the Predominant Ribotypes of Actinomyces naeslundii genospecies 1 and 2 in Samples from Enamel and from Healthy and Carious Root Surfaces of Teeth
Authors: Bowden G.H.W. , Nolette N. , Ryding H. , Cleghorn B.M.
Published: January 2009

The bacterial communities associated with root caries are highly diverse and undergo succession during lesion formation. Consequently, root caries is said to have a polymicrobic etiology, typified by variation in the predominant species among samples from different lesions. Despite the polymicrobic etiology, A. naeslundii genospecies 1 and 2 (previously A. viscosus) have consistently been shown to be associated with root caries in humans; they predominate in some lesions and have been suggested to play a significant role in the disease. Several genetic variants of A. naeslundii are known to be present among the oral A. naeslundii population of an individual. The current study was initiated to explore the possibility that a variant in these A. naeslundii populations had characteristics which made it best fitted to colonize or promote root-surface caries lesions. Using ribotyping to detect variants, we tested the hypothesis that 'a ribotype of A. naeslundii best fitted to the environment would be selected and predominate in the A. naeslundii population of lesions'. Samples of plaque from enamel, normal root surfaces, plaque overlying the lesion, and material from within the lesion were taken from nine patients with soft root caries. The flora from 14 lesions and 9 enamel sites was analyzed on selective and non-selective media, and A. naeslundii genospecies were identified by serology. We ribotyped 972 isolates, showing 54 different patterns. Between 6 and 20 ribotypes were isolated from eight of nine patients. In general, each site from a patient showed a similar distribution of ribotypes. These results do not support the hypothesis and suggest that any phenotypic characters that allow A. naeslundii genospecies 1 and 2 to colonize or contribute to the formation of root-caries lesions are common among strains identified by ribotyping.
Thickness of Acquired Salivary Pellicle as a Determinant of the Sites of Dental Erosion
Authors: Amaechi B.T. , Higham S.M. , Edgar W.M. , Milosevic A.
Published: January 2009

Dental erosion shows a typical distribution pattern within the dental arches. Tooth protection from erosion by salivary pellicle has been shown in vitro, but the hypothesis that pellicle may differ quantitatively at sites of erosion has not been investigated. This study aimed to determine the thickness of acquired salivary pellicle within the dental arches, investigate the possible relationship of this thickness to the distribution and severity of erosion within the arches, and confirm the protective effect of pellicle against dental erosion. Eight enamel blocks were produced from each of 5 bovine incisors assigned to five volunteers. Each block was further cut into 2 slabs, producing control and experimental slabs. Pellicle developed on experimental slabs located on 8 intra-oral sites after 1 hr of exposure was stained by "sheep anti-human IgGAM-FITC". Slabs were then visualized, and pellicle thickness measured, by confocal laser scanning microscopy. Eroded enamel lesions were produced in experimental and control slabs by means of pure orange juice. The degree of erosion was quantified by transverse microradiography. Pellicle thickness varied significantly within the dental arches and among individuals. An inverse relationship (r = -0.96, p < 0.001) was observed between the degree of erosion and pellicle thickness. Significant differences in erosion were observed between slabs with and those without pellicle. This study has shown that the thickness of acquired salivary pellicle varies within the dental arches, which may be responsible for the site-specificity of dental erosion, and that pellicle does protect the teeth from erosion.
Ultrastructural Properties of Laser-irradiated and Heat-treated Dentin
Authors: Rohanizadeh R. , LeGeros R.Z. , Fan D. , Jean A. , Daculsi G.
Published: January 2009

Previous studies using scanning electron microscopy and infrared absorption spectroscopy reported that laser irradiation causes compositional changes in enamel. The purpose of this study was to evaluate the ultrastructural and compositional changes in dentin caused by irradiation with a short-pulse laser (Q-switched Nd:YAG). The irradiated and non-irradiated areas of the lased dentin samples were investigated by scanning (SEM) and transmission electron microscopy (TEM), micro-micro electron diffraction, and electron microprobe analysis of dispersive energy (EDX). Heat-treated dentin was similarly investigated. This study demonstrated that laser irradiation resulted in the recrystallization of dentin apatite and in the formation of additional calcium phosphate phases consisting of magnesium-substituted β-tricalcium phosphate, (3-TCMP, β-(Ca,Mg)3(PO4)2, and tetracalcium phosphate, TetCP, Ca4(PO4)O. TEM analyses of the modified and unmodified zones of the irradiated areas showed two types of crystal populations: much larger crystals from the modified zone and crystals with size and morphology similar to those of dentin apatite in the unmodified zone. The morphology of crystals in the modified zones in the irradiated dentin resembled those of dentin sintered at 800 or 950°C. In the irradiated areas (modified and unmodified zones), the Ca/P ratio was lower compared with that in the non-irradiated dentin. The Mg/Ca ratio in the modified zones was higher than that in the unmodified zones and in the non-irradiated dentin. In sintered dentin, the Mg/Ca ratio increased as a function of sintering temperature. The ultrastructural and compositional changes observed in laser-irradiated dentin may be attributed to high temperature and high pressure induced by microplasma during laser irradiation. These changes may alter the solubility of the irradiated dentin, making it less susceptible to acid dissolution or to the caries process.
Dating, sex, and substance use predict increases in adolescents' subjective age across two years
Authors: Galambos Nancy L. , Albrecht Arne K. , Jansson S. Mikael
Published: January 2009

This study examined the nature of the relationship between adolescents' subjective age (how old they feel) and chronological age, and explored whether dating, sex, and substance use predicted increases in adolescents' subjective age across a two-year period. The participants were 570 adolescents who were interviewed when they were first ages 12—19 and again two years later (ages 14—21). Results were that a quadratic function characterized the relationship between chronological and subjective age: subjective age increased from age 14 to 18.25 years, and then declined. Adolescents who dated, reported having sex, used alcohol, and used drugs at time 1 experienced an increased subjective age, that is, they felt older than less experienced adolescents by time 2. An older subjective age at time 1 did not predict increases in dating, sex, and substance use behaviors, with one exception: smoking. The results are consistent with theories assuming that self-perceptions of maturity may arise from engaging in “adult-like” behaviors.
Prediction of subjective age, desired age, and age satisfaction in older adults: Do some health dimensions contribute more than others?
Authors: Hubley Anita M. , Russell Lara B.
Published: January 2009

Of all the variables that have been shown to contribute to subjective age, health variables typically explain the greatest proportion of variance, with poorer health related to feeling older than one's chronological age. Despite the significant contribution of health to subjective age, little research has explored the relative importance of different dimensions of health to subjective age. The primary aim of the present study was to examine the relative importance of various physical, mental, social, and emotional dimensions of health, as well as satisfaction with health, to measures of subjective age, desired age, and satisfaction with age in a sample of 875 older men and women. The results indicated that: (1) certain combinations of health dimensions and satisfaction with health accounted for relatively large proportions (20—36%) of the variance in subjective age and satisfaction with age but not desired age; (2) subjective age and satisfaction with age were explained by different combinations of health dimensions; and (3) the health predictors of subjective age and satisfaction with age differed somewhat for men and women and for young-old and old-old groups.
On the question of an identity status category order: Rasch model step and scale statistics used to identify category order
Authors: Al-Owidha Amjed , Green Kathy E. , Kroger Jane
Published: January 2009

The question of whether or not a developmental continuum underlies James Marcia's identity statuses has been a topic of debate among identity researchers for nearly 20 years. This study addressed the prefatory question of whether the identity statuses can be empirically ordered in a theoretically optimal way. This question was addressed via use of Rasch model threshold and scale statistics, which effectively differentiated empirically optimal from suboptimal category orders. All permutations of Marcia's 4 identity statuses were generated in relation to stages from Loevinger's model of ego development and Kegan's model of self—other differentiation. The optimal identity status order found was diffusion, foreclosure, moratorium, to achievement in 2 sets of analyses, and diffusion combined with foreclosure to moratorium, to achievement in 2 additional sets of analyses. The order diffusion, foreclosure, achievement, to moratorium performed nearly as well in one set of analyses. Results, in general, support the theoretically optimal category order. Rasch model threshold and scale statistics can be effectively applied to place categories into an empirically optimal order or to assess the match between theoretical and empirical category orders.
The `problem' of anti-social behaviour and the policy knowledge base: Analysing the power/knowledge relationship
Authors: Prior David
Published: January 2009

The high priority given to tackling anti-social behaviour in current government policy might generate an expectation that knowledge of the nature and extent of the problem would provide an empirical underpinning for policy. However, a detailed examination of the state of official `knowledge' of the problem of anti-social behaviour shows that there are substantial gaps and ambiguities in what is known, and disjunctures between some of the claims made by government about its approach and what the official evidence seems to say. The article explores the reasons for the government's lack of empirical engagement with the `problem' of anti-social behaviour in the context of the relationship between power and knowledge in current policy.
Kerbcrawler rehabilitation programmes: Curing the `deviant' male and reinforcing the `respectable' moral order
Authors: Sanders Teela
Published: January 2009

This paper has two aims: to outline the current policy and ideology behind `tackling demand' for commercial sex through targeting `kerbcrawlers' and to critique support for and rise of `kerbcrawler rehabilitation programmes' in the UK. Such attempts to `reform' sexual `deviants' through a criminal treatment process are criticized on accounts of ineffectiveness; resource intensiveness; the content of the programme; the disregard for legal process and theory; and the damaging effects of the programme. The messages behind the policy and rehabilitation programmes are examined through the discourse of respectability, and the desire to reinforce a sexual order by scapegoating this group of men as the sexual `other' alongside female street sex workers. The discourses behind New Labour prostitution policy are examined where it is argued that the governance of prostitution through criminalization amounts to `moral engineering'.
The Biopolitical Imaginary of Species-being
Authors: Dillon Michael , Lobo-Guerrero Luis
Published: January 2009

This article revises Foucault's account of biopolitics in the light of the impact of the molecular and digital revolutions on `the politics of life itself'. The confluence of the molecular and digital revolutions informationalizes life, providing an account of what it is to be a living thing in terms of complex adaptive and continuously emergent, informationally constituted, systems. Also revisiting Foucault's The Order of Things and its interrogation of the modern analytics of finitude, the article argues that our contemporary politics of life is therefore distinguished by the quasi-transcendentals that now distinguish informationalized life: circulation, connectivity and complexity. Here, too, the article argues, the figure of Man, which once united the quasi-transcendentals of life, labour and language, is replaced by the contingency that now unites circulation, connectivity and complexity. Observing that a life of continuous emergence is also one in which production is continuously allied with destruction, such a life is lived as the continuous emergency of its own emergence. This account of contemporary biopolitics, together with its emergency of emergence, contrasts, in particular, with that offered by Agamben in his appropriation of Schmitt.
The Idea of Europe and the Ideal of Cosmopolitanism in the Work of Julia Kristeva
Authors: Varsamopoulou Evy
Published: January 2009

This article puts forward a critical investigation and comparative assessment of Julia Kristeva's political writing on Europe and cosmopolitanism. Kristeva's reflections on the status of the stranger in the European religious and secular traditions, and her persistent argument on the need to constructively reformulate what is most conducive to a present and future cosmopolitanism from within those traditions and discourses, have already been recognized. What this article addresses is the need for a constructive critical dialogue with the themes and arguments of Kristeva's writing on these issues in the context of recent writing on cosmopolitanism. The article is concerned with ethical cosmopolitanism, as Kristeva's thought mostly bears on the subjective, interpersonal and communal dimensions of cosmopolitanism. Two main problems are identified that crucially undermine Kristeva's thinking on Europe. First, Kristeva's views on the present and future of Europe repeatedly confine the idea of Europe to the representation of a very particular history of French modernity that is only tempered by occasional, comparative yet complementary, references to the USA. The second problem concerns the use of psychoanalytic theories of questionable validity to support cultural analyses and theoretical propositions of dubious value for a cosmopolitan ethos or politics.
A Message in a Bottle
Authors: Kurasawa Fuyuki
Published: January 2009

In response to distant suffering, global civil society is being consumed by a generalized witnessing fever that converts public spaces into veritable machines for the production of testimonial discourses and evidence. However, bearing witness itself has tended to be treated as an exercise in truth-telling, a juridical outcome, a psychic phenomenon or a moral prescription. By contrast, this article conceives of bearing witness as a transnational mode of ethico-political labour, an arduous working-through produced out of the struggles of groups and persons who engage in testimonial tasks in order to confront corresponding perils produced by instances of situational or structural violence; it is the work of witnessing, the normative and political substance generated through the performance of patterns of social action, which matters. Using Celan's allegory of the poem as a message in a bottle, I consider bearing witness as a web of cosmopolitan testimonial practices structured around five dialectically related tasks and perils: giving voice to mass suffering against silence (what if the message is never sent or does not reach land?); interpretation against incomprehension (what if it is written in a language that is undecipherable?); the cultivation of empathy against indifference (what if, after being read, it is discarded?); remembrance against forgetting (what if it is distorted or erased over time?); and prevention against repetition (what if it does not help to avert other forms of suffering?).
Hyaluronic Acid/Polylysine Hydrogel as a Transfer System for Transplantation of Neural Stem Cells
Authors: Ren Yong-Juan , Zhou Zi-You , Cui Fu-Zhai , Ying Wang  , Zhao Jun-Peng , Xu Qun-Yuan
Published: January 2009

Graft integration and survival are major factors that limit cell therapy for diseases and injury in the central nervous system. Efforts to improve graft survival and integration have focused on the development of biocompatible scaffolds to support neural cells. In this study, rat neural stem cells (NSC), including neurospheres and single cells, were seeded into hyaluronic acid/polylysine hydrogels. Confocal microscopy was used to noninvasively investigate the key cell phonotypes. After culture for 5 days, single NSC had survived and differentiated into neurons and astrocytes, while neurosphereforming cells had migrated from their original aggregate and maintained the NSC phonotype. These studies, carried out in the absence of serum, identified HA/polylysine hydrogels as potential synthetic cell carriers for transplantation of NSC.
Surface Properties of Chitosan Films Modified with Polycations and Their Effects on the Behavior of PC12 Cells
Authors: Zhenhuan Zheng  , Yujun Wei  , Gan Wang  , Aijun Wang Qiang Ao  , Yandao Gong  , Xiufang Zhang
Published: January 2009

A series of composite films were prepared by blending chitosan with three polycations, poly(L-lysine), polyethyleneimine, and poly-L-ornithine, in specific blend proportions. The surface properties of the composite films, including surface topography, chemistry, and wettability, were examined by atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle assay, respectively. For all composite films, blending with different polycations produced different nanoscaled surface topographical features (particles, granules, fibers, and islands) in addition to inducing changes in surface chemistry and wettability. PC12 cells were cultured on these composite films to evaluate the effects of surface properties on cell behavior. The PC12 cell behavior was holistically affected by surface topography, chemistry, and wettability; the cells also displayed responses to surface topography. On the surfaces with fiber topographic features, the PC12 cells exhibited significantly higher levels of adhesion, proliferation, and differentiation when compared to particle, granule, or island dominant surfaces. It appears that the surface topography of chitosan and chitosan-derived materials may play an important role in regulating nerve cell behavior and that topographic modification can be utilized for the applications of chitosan and chitosan-derived materials in nerve or other tissue regeneration.
Salivary Histatin 5 and its Similarities to the Other Antimicrobial Proteins in Human Saliva
Authors: Edgerton M. , Koshlukova S.E.
Published: January 2009

Non-immune salivary proteins-including lactoperoxidase, lysozyme, lactoferrin, and histatins-are key components of the innate host defense system in the oral cavity. Many antimicrobial proteins contain multiple functional domains, with the result that one protein may have more than one mechanism of antimicrobial activity. These domains may be separated by proteolytic cleavage, creating smaller proteins with functional antimicrobial activity in saliva as described for lysozyme, lactoferrin, and histatins. These small cationic proteins then exert cytotoxic activity to oral bacteria and fungi. Salivary histatin 5 initiates killing of C. albicans through binding to yeast membrane proteins and non-lytic release of cellular ATP. Extracellular ATP may then activate fungal ATP receptors to induce ultimate cell death. This mechanism for fungal cytotoxicity may be shared by other antimicrobial cationic proteins. Microbicidal domains of salivary and host innate proteins should be considered as potential therapeutic agents in the oral cavity.
Saliva and Dental Caries
Authors: Lenander-Lumikari M. , Loimaranta V.
Published: January 2009

Caries is a unique multifactorial infectious disease. Our understanding of etiological factors, the progress of the disease, and the effectiveness of prophylactic procedures have led us to believe that we understand the disease. However, we still have too few answers to many questions: "Why can we not predict who will get the disease?" "Why do we not become immunized?" "How much saliva is enough?" or "Which salivary components are protective?" and "Which salivary components predispose for caries?" It is generally accepted, however, that saliva secretion and salivary components secreted in saliva are important for dental health. The final result, "caries to be or not to be", is a complex phenomenon involving internal defense factors, such as saliva, tooth surface morphology, general health, and nutritional and hormonal status, and a number of external factors-for example, diet, the microbial flora colonizing the teeth, oral hygiene, and fluoride availability. In this article, our aim is to focus on the effects of saliva and salivary constituents on cariogenic bacteria and the subsequent development of dental caries.
Natura History an Prevention of Radiation Injury
Authors: O'Connell A.C.
Published: January 2009

Radiation therapy for cancers of the head and neck can irreversibly damage the salivary glands. Xerostomia (subjective oral dryness) develops within the first week of therapy and is progressive, with devastating effects on the quality of life of the individual. The xerostomia does not correlate with the degree of salivary gland hypofunction. The mechanism of tissue injury in humans is still unclear, but much progress has been made with animal models. This paper reviews the natural history of radiation damage to human salivary glands and highlights the inter-individual variations in the responses to and recovery from therapeutic radiation. The degree of salivary gland damage is correlated to the dose of radiation delivered and the volume of gland included in the field of radiation. The molecular mechanism of acute radiation damage is not fully understood; however, long-term salivary gland dysfunction is associated with both loss of gland weight and loss of acinar cells. Various strategies have been used to prevent or alleviate the problem of salivary gland hypofunction following therapeutic radiation. This paper reviews the progress made to date and the possibilities for future interventions to prevent radiation damage.
Heterogeneity of High-molecular-weight Human Salivary Mucins
Authors: Offner G.D. , Troxler R.F.
Published: January 2009

The existence of high-molecular-weight glycoproteins in saliva and salivary secretions has been recognized for nearly 30 years. These proteins, called mucins, are essential for oral health and perform many diverse functions in the oral cavity. Mucins have been intensively studied, and much has been learned about their biochemical properties and their interactions with oral micro-organisms and other salivary proteins. In the past several years, the major high-molecular-weight mucin in salivary secretions has been identified as MUC5B, one of a family of 11 human mucin gene products expressed in tissue-specific patterns in the gastrointestinal, respiratory, and reproductive tracts. MUC5B is one of four gel-forming mucins which exist as multimeric proteins with molecular weights greater than 20-40 million daltons. The heavily glycosylated mucin multimers form viscous layers which protect underlying epithelial surfaces from microbial, mechanical, and chemical assault.

Another class of mucin molecules, the membrane-bound mucins, is structurally and functionally distinct from the gel-forming mucins. These proteins do not form multimers and can exist as both secreted and membrane-bound forms, with the latter anchored to epithelial cell membranes through a short membrane-spanning domain. In the present work, we show that two of the membrane-bound mucins, MUC1 and MUC4, are expressed in all major human salivary glands as well as in buccal epithelial cells. While the functions of these mucins in the oral environment are not understood, it is possible that they form a structural framework on the cell surface which not only is cytoprotective, but also may serve as a scaffold upon which MUC5B, and possibly other salivary proteins, assemble.
First Insights into the Molecular Basis of Pleomorphic Adenomas of the Salivary Glands
Authors: Voz M.L. , Van de Ven W.J.M. , Kas K.
Published: January 2009

Pleomorphic adenoma, or mixed tumor of the salivary glands, is a benign tumor originating from the major and minor salivary glands. Eighty-five percent of these tumors are found in the parotid gland, 10% in the minor (sublingual) salivary glands, and 5% in the submandibular gland. It is the most common type of salivary gland tumor, accounting for almost 50% of all neoplasms in these organs. In fact, after the first observation of recurrent loss of chromosome 22 in meningioma, this was the second type of benign tumor for which non-random chromosomal changes were reported. The rate of malignant change with the potential to metastasize has been reported to be only 2 to 3%, and only a few cases of metastasizing pleomorphic salivary gland adenomas have been described to date. The fact that these tumors arise in organs located in an ontogenetic transitional zone, a region where endoderm and ectoderm meet, might be one of the reasons for the often-problematic histopathological classification. This type of benign tumor has been cytogenetically very well-characterized, with several hundreds of tumors karyotyped. In addition to the cytogenetic subgroup with an apparently normal diploid stemline (making up approximately 30% of the cases), three major cytogenetic subgroups can be distinguished. In addition to a subgroup showing non-recurrent clonal abnormalities, another subgroup is composed of tumors with various translocations involving 12ql5. By far the largest cytogenetic subgroup, however, consists of tumors with chromosome 8 abnormalities, mainly showing translocations involving region 8ql2. The most frequently encountered aberration in this group is a t(3;8)(p21;q12).
Prospects for Re-engineering Salivary Glands
Authors: Baum B.J.
Published: January 2009

In the last decade, two areas of biomedical research-gene therapy and tissue engineering-have especially captured the imagination of the public. Both areas offer the potential for the treatment of clinical conditions that now are considered impossible or extremely difficult to manage by conventional therapeutic measures. Gene therapy has made remarkable scientific progress in the laboratory, but has yet to realize its enormous clinical promise. Tissue engineering studies have led to some tangible clinical breakthroughs, but the routine replacement of whole internal organs is still well into the future. This report will examine the applications of gene therapy and tissue engineering to salivary glands, with a focus on the repair of irreversible gland damage.
Pulp-capping with Recombinant Human Insulin- like Growth Factor I (rhIGF-I) in Rat Molars
Authors: Lovschall H. , Fejerskov O. , Flyvbjerg A.
Published: January 2009

The aim of this study was to explore pulp healing and reparative dentinogenesis following pulp-capping by using recombinant human insulin-like growth factor I (rhIGF-I). Exposures were made through the mesial pulp horn in first upper molars in two-month-old Wistar rats. The pulp was covered with one dose of sterile 4% methylcellulose gel containing either 400 ng rhIGF-I or saline in contralateral controls. The exposure site was closed with sterile Teflon membrane, and the cavity was filled with IRM cement. Additional molars were capped with Dycal as controls. After 3, 7, or 28 days, animals were anesthetized and fixed by intravascular glutaraldehyde perfusion. Molars were decalcified and processsed for histological analysis and cut with membrane and residual methacrylate from IRM in situ. Only specimens with acceptable pulp sealing according to blinded microscopy control were included. On day 3, identical inflammatory responses in the upper pulp were observed in molars with rhIGF-I gel or control gel. On day 7, granulation tissue ingrowth had partly replaced inflammatory infiltration in both groups. After 28 days, complete dentin bridging and tubular dentin formation were observed more frequently and closer to the test substance containing rhIGF-I. The reparative dentin response to capping with rhIGF-I was similar to that after the use of Dycal. In conclusion, microscopic control of membrane sealing in situ gives valid information on the more subtle pulp effects of growth factors. The observations suggest that pulp-capping of rat molars by means of rhIGF-I enhances reparative dentinogenesis in comparison with vehicle controls.
Sex- and Age-related Differences in Primary and Secondary Dentin Formation
Authors: Zilberman U. , Smith P.
Published: January 2009

Clinical studies carried out on dentin thickness in adults, as well as experimental studies carried out on ovariectomized animals, indicate that odontoblast activity, like that of osteoblastic cells, differs in the two sexes. To examine the evidence for differences in odontoblast activity before puberty, we have measured dentin thickness and other crown dimensions from bite-wing radiographs of the lower first molars in 240 children aged 4-16 years. The radiographs were obtained from pedodontic clinics throughout Israel. Only teeth without caries or fillings were used, and the study population had minimal attrition. The results showed that dentin thickness, measured on the roof of the pulp chamber, was significantly greater in boys than in girls at all ages, and that the differences increased during puberty. The differences remained highly significant even when standardized for crown size. They demonstrate that dimorphism in dentin thickness is present even in the earliest stages of odontogenesis and increase with puberty.
Molecular Aspects of Tooth Pathogenesis and Repair: in vivo and in vitro Models
Authors: About Imad , Mitsiadis Thimios A.
Published: January 2009

Several growth factors and extracellular matrix molecules, which are expressed during embryonic tooth development, are re-expressed in dental tissues under pathological conditions. Pathological conditions such as caries lesions and dental injuries are often lethal to the odontoblasts, which are then replaced by other pulp cells. These cells are able to differentiate into odontoblast-like cells and produce a reparative dentin. Here we demonstrate the in vivo distribution of several molecules in human permanent teeth under normal and pathological conditions. The intermediate filament protein nestin, which is a marker of young odontoblasts, is absent from old permanent teeth. Similarly, the Notch protein, which is involved in cell fate specification and is localized in the sub-odontoblastic cell layer during odontogenesis, is not detected in adult dental tissues. In carious and injured teeth, nestin is expressed in a selective manner in odontoblasts surrounding the injury site, while Notch is expressed in the sub-odontoblastic layer of cells. We reproduced this physiological event in an in vitro culture system. Pulp cells cultured in the presence of P-glycerophosphate formed mineralization nodules. As odontoblasts, pulp cells contributing to the nodule formation express type I collagen, osteonectin, dentin sialophosphoprotein, and nestin. In this in vitro assay system, nestin is up-regulated after local application of Bone Morphogenetic Protein 2 and 4. Fourier transform infrared microspectroscopy showed that both the organic and the mineral compositions of the nodules have the characteristics of human dentin and differ from those of enamel and bone. These findings show that both the molecular and the mineral characteristics of the human dentin matrix are respected in the in vitro culture conditions.
Expression of TGF-β Receptors I and II in the Human Dental Pulp by in situ Hybridization
Authors: Sloan A.J. , Couble M.-L. , Bleicher F. , Magloire H. , Smith A.J. , Farges J.-C.
Published: January 2009

Members of the TGF-β family of growth factors are important in modulation of odontoblast secretory activity during dental tissue repair. Odontoblast expression of TGF-β isoforms during development leads to their sequestration within the dentin matrix, from where they may be released during carious injury and participate in reparative processes. Two receptors, implicated in TGF-p-mediated cell signaling, have been identified immunohistochemically in both odontoblasts and pulpal cells of healthy and carious human molar teeth. This study aimed to characterize the expression of the TGF-β receptors I and II in sound and carious teeth by means of in situ hybridization, to help our understanding of the response of these cells to TGF-β stimulation. Sound and carious human third molar teeth were routinely processed immediately following extraction, and 10-μm paraffin-embedded sections prepared. These sections were hybridized with 32P-labeled probes to TGF-β receptors I and II, and the subsequent signal was detected by autoradiography. mRNA for both receptors I and II was mainly detected within the odontoblasts and nerve-associated cells of healthy tissues, with expression at lower levels seen within the subodontoblast and pulp core cells. The expression in odontoblasts was higher for TGF-β receptor I than for receptor II. Expression of both receptors was more homogenous in all pulp cells within carious teeth, because of an increase of signal within the underlying pulp cell population, including blood-vessel-associated cells. We conclude that the TGF-β receptors I and II were expressed in odontoblasts and pulp cells, and that subtle variations in the levels of their expression could be involved in the tissue response to injury.
Epigenetic Signals during Odontoblast Differentiation
Authors: Lesot H. , Lisi S. , Peterkova R. , Peterka M. , Mitolo V. , Ruch J.V.
Published: January 2009

Odontoblast terminal differentiation occurs according to a tooth-specific pattern and implies both temporo-spatially regulated epigenetic signaling and the expression of specific competence. Differentiation of odontoblasts (withdrawal from the cell cycle, cytological polarization, and secretion of predentin/dentin) is controlled by the inner dental epithelium, and the basement membrane (BM) plays a major role both as a substrate and as a reservoir of paracrine molecules. Cytological differentiation implies changes in the organization of the cytoskeleton and is controlled by cytoskeleton-plasma membrane-extracellular matrix interactions. Fibronectin is re-distributed during odontoblast polarization and interacts with cell-surface molecules. A nonintegrin 165-kDa fibronectin-binding protein, transiently expressed by odontoblasts, is involved in microfilament reorganization. Growth factors (TGFβ1,2,3/BMP2,4, and 6), expressed in tooth germs, signal differentiation. Systemically derived molecules (IGF1) may also intervene. IGF1 stimulates cytological but not functional differentiation of odontoblasts: The two events can thus be separated. Immobilized TGFβ1 (combined with heparin) induced odontoblast differentiation. Only immobilized TGFβ1 and 3 or a combination of FGF1 and TGFβ1 stimulated the differentiation of functional odontoblasts over extended areas and allowed for maintenance of gradients of differentiation. Presentation of active molecules in vitro appeared to be of major importance; the BM should fulfill this role in vivo by immobilizing and spatially presenting TGF(3s. Attempts are being made to investigate the mechanisms which spatially control the initiation of odontoblast differentiation and those which regulate its propagation. Analysis of molar development suggested that odontoblast differentiation and crown morphogenesis are interdependent, although the possibility of co-regulation requires further investigation.
Interactions Between Salmonella Typhimurium, Enteropathogenic Escherichia Coli (EPEC), and Host Epithelial Cells
Authors: Finlay B.B.
Published: January 2009

The interactions that occur between pathogenic micro-organisms and their host cells are complex and intimate. We have used two enteric pathogens, Salmonella typhimurium and enteropathogenic Escherichia coli (EPEC), to examine the interactions that occur between these organisms and epithelial cells. Although these are enteric pathogens, the knowledge and techniques developed from these systems may be applied to the study of dental pathogens. Both S. typhimurium and EPEC disrupt epithelial monolayer integrity, although by different mechanisms. Both pathogens cause loss of microvilli and re-arrangement of the underlying host cytoskeleton. Despite these similarities, both organisms send different signals into the host cell. EPEC signal transduction involves generation of intracellular calcium and inositol phosphate fluxes, and activation of host tyrosine kinases that results in tyrosine phosphorylation of a 90-kDa host protein. Bacterial mutants have been identifed that are deficient in signaling to the host. We propose a sequence of events that occur when EPEC interacts with epithelial cells. Once inside a host cell, S. typhimurium remains within a vacuole. To define some of the parameters of the intracellular environment, we constructed genetic fusions of known genes with lacZ, and used these fusions as reporter probes of the intracellular vacuolar environment. We have also begun to examine the bacterial and host cell factors necessary for S. typhimurium to multiply within epithelial cells. We found that this organism triggers the formation of novel tubular lysosomes, and these structures are linked with intracellular replication.
Regulation of Hemin and Iron Transport in Porphyromonas Gingivalis
Authors: Genco C.A.
Published: January 2009

As with other pathogens, a requirement for the in vivo growth of Porphyromonas gingivalis is that the organism must be capable of obtaining iron from the host. The ability to utilize hemin and hemin-containing compounds for nutritional iron has been documented for several pathogenic bacteria, including P. gingivalis; however, the mechanisms involved in hemin uptake are poorly defined. I have determined that P. gingivalis transports the entire hemin moiety into the cell by an energy-dependent mechanism and that the binding and accumulation of hemin are induced by growth of cultures in the presence of hemin. A model of hemin transport in P. gingivalis consistent with these results is presented. I have also found that, in P. gingivalis, hemin regulates the expression of several putative virulence factors; this in turn results in the increased virulence potential of P. gingivalis as assessed in an animal model. Regulation of hemin-responsive genes in P. gingivalis may occur by a negative regulator, as has been described in other pathogenic organisms.
The Regulation of Leukotoxin Production in Actinobacillus Actinomycetemcomitans Strain JP2
Authors: Spitznagel J. , Kraig E. , Kolodrubetz D.
Published: January 2009

Actinobacillus actinomycetemcomitans ( A.a.) can produce a potent leukotoxin that is thought to be involved in evasion of the host immune response. In order to understand the role of A.a. and its leukotoxin in the initiation and progression of periodontal disease, it is important determine how the expression of A.a. virulence factors might be regulated by the local periodontal micro-environment. To facilitate the measurement of leukotoxin levels, a leukotoxin-β-galactosidase gene fusion was constructed and recombined into the chromosome of A.a. strain JP2 at the leukotoxin locus. The resulting strain, AAM17, produces β-galactosidase under control of the leukotoxin promoter. It also produces leukotoxin, since integration of the gene fusion into the chromosome was designed to produce a duplication of the leukotoxin gene. This strain was used to measure the change in leukotoxin level in response to alterations in two environmental signals: iron concentration and oxygen tension. When AAM17 was grown in iron-limited media that did not alter growth rate but did increase the levels of other iron-regulated proteins, the levels of the leukotoxin-p-galactosidase were similar to those found in AAM17 grown in iron-replete media. These results were confirmed in strains AAM17 and JP2 by leukotoxicity assays and RNA blots. Aerobic growth of AAM17 resulted in a three-fold decrease in leukotoxin β-galactosidase activity compared with anaerobically grown cells. These results indicate that the A.a. leukotoxin is regulated by some of the environmental signals that may vary in the gingival crevice.
Reducing the Cariogenic Effect of Sugar by Adding Fluoride to Sugar-Project Background
Authors: O'Mullane D.M.
Published: January 2009

For various reasons, the use of the more widely used fluoride vehicles-such as water, salt, and toothpastes-is not feasible in some communities. There is some theoretical and laboratory evidence to support the view that adding fluoride to sugar and sugar products has potential to reduce their cariogenic effect. However, the clinical evidence is minimal. The minimum concentration of fluoride in sugar which will bring about a caries-preventive effect needs to be determined. Logistical issues requiring investigation include the most efficient method of adding fluoride to sugar and the distribution and consumption patterns of sugar in target populations. The practical application of this knowledge to large populations is the priority focus of this investigation.
Identification of CG-1, a Natural Peptide Antibiotic Derived from Human Neutrophil Cathepsin G
Authors: Miyasaki K.T. , Qu X.-D. , Harwig S.S.L. , Cho Y. , Lehrer R.I.
Published: January 2009

Cathepsin G is a neutral serine protease of the granzyme B family which is found in human PMN, cells known to be important in the defense of the periodontium against periodontal bacteria. We propose that cathepsin G serves as a "pro-antibiotic" containing peptide domains which express selective antibiotic properties. In this study, we used HPLC to separate the low-molecular-weight peptides derived from the ultrafiltrate of a granule extract from unstimulated PMN. One of the peptides exhibited intense bactericidal activity as determined by radial diffusion overlay assay (against Escherichia coli ML-35P), an amino-terminal sequence "RVSSFLPWIR...", and a 3.1-kDa molecular mass determined by electrospray ionization-mass spectrometry. The sequence and mass are consistent with the C-terminus of cathepsin G deduced by cDNA analysis. These findings support the hypothesis that antibiotic peptides derived from cathepsin G occur naturally in human PMN. Since this is the first naturally occurring antibiotic peptide derived from cathepsin G, we designate it "CG-1".