bluuebunny/crossref_metadata_2025 huggingface dataset:
An exploration of the accuracy of an invasive method for measuring the volume of specimens of Amoeba proteus
Authors: Whalen  , Demarco
Published: March 2003

A method is described for measuring the volume of individual specimens of Amoeba proteus which utilizes an easily constructed compressor to flatten the specimen to a known thickness. The microscopic image of the flattened specimen is captured on tape, digitized and analysed with the NIH Image software. The results from one specimen are given to illustrate the sources and magnitude of errors affecting these volume measurements.
Proximal electromagnetic shear forces
Authors: Ayars  , Aspnes  , Moyer  , Paesler
Published: March 2003

We perform a simple model calculation to estimate the electromagnetically induced shear force caused by a current dissipation when a charged tip is moved parallel to a conducting material. For parameters typical in shear force imaging, the force is many orders of magnitude below reported values. Thus, proximal electromagnetic tip–sample forces can be neglected in discussions of shear force imaging.
Stereological estimation of the total number of ECL cells and related parameters using the smooth, vertical fractionator in the rat oxyntic mucosa
Authors: Bendtsen T. F. , Nyengaard J. R. , Grimelius L. , Gundersen H. J. G.
Published: March 2003

During the last 10 years many attempts have been made to estimate the number of enterochromaffin‐like (ECL) cells in various animal studies. This is the first presentation of an unbiased stereological estimator of the total number of histamine‐positive ECL cells per rat and linked to estimators of related parameters: total volume of the oxyntic mucosa, total oxyntic mucosal surface area, total oxyntic serosal surface area, surface amplification factor, average thickness of the oxyntic mucosa, total and mean volume of the ECL cells, total number of oxyntic glands and pits, mean number of ECL cells per gland, and mean number of ECL cells and glands per oxyntic serosal surface area.

This study is the first application of the smooth fractionator and includes a description of all sources of sampling variance in the smooth fractionator design with newly developed predictors.
On the influence of imaging conditions and algorithms on the quantification of surface topography
Authors: Wendt U. , Stiebe‐Lange K. , Smid M.
Published: March 2003

The influence of the microscopical magnification resulting in different voxel size and shape and of the algorithm on parameters used for the quantification of the surface topography is studied using topographical images obtained by confocal laser scanning microscopy. Fracture surfaces and wire‐eroded surfaces of steel were used as samples. The values obtained for the global topometry parameters normalized surface area, mean profile segment length and fractal dimension depend with different degrees on the microscopic magnification and on the algorithm used to compute these values. The topometry values can only be used to establish correlations between the topography and materials properties and for the modelling of surface generating processes if the imaging and computing details are given.
Impairment of cytoskeleton‐dependent vesicle and organelle translocation in green algae: combined use of a microfocused infrared laser as microbeam and optical tweezers
Authors: Holzinger A. , Monajembashi S. , Greulich K. O. , Lütz‐Meindl U.
Published: March 2003

A Nd‐YAG laser at 1064 nm is used as optical tweezers to move intracellular objects and a laser microbeam to cause impairment of cytoskeleton tracks and influence intracellular motions in desmidiaceaen green algae. Naturally occurring migrations of large nuclei are inhibited in Micrasterias denticulata and Pleurenterium tumidum when the responsible microtubules are targeted with a laser microbeam generating 180 mW power in the focal plane. Impairment of the microtubule tracks appears to be irreversible, as the nucleus cannot pass the former irradiated area in Pleurenterium or remains abnormally dislocated in Micrasterias. The actin filament‐dependent movement of secretory vesicles and smaller particles can be manipulated by the same IR‐laser at 90 mW when functioning as optical tweezers. In Closterium lunula particles are displaced from their cytoplasmic tracks for up to 10 µm but return to their tracks immediately after removing the light pressure gained by the optical tweezers. The cytoplasmic tracks consist of actin filament cables running parallel to the longitudinal axis of Closterium cells as depicted by Alexa phalloidin staining and confocal laser scanning microscopy. Dynamics and extensibility of the cytoplasmic strands connecting particles to the tracks are also demonstrated in the area of large vacuoles which are surrounded by actin filament bundles. In Micrasterias trapping of secretory vesicles by the optical tweezers causes irreversible malformations of the cell shape. The vesicle accumulation itself dissipates within 30 s after removing the optical tweezers, also indicating reversibility of the effects induced, in the case of actin filament‐mediated processes.
Time‐resolved, three‐dimensional quantitative microscopy of a droplet spreading on solid substrates
Authors: Be’er A. , Lereah Y.
Published: March 2003

A polarized microscope was used to study the spreading of mercury droplets on thin silver films. Using the differential interference contrast (DIC) method and semi‐quantitative measurements of the optical path difference (OPD), the three‐dimensional shape of the liquid droplet that wets the solid surface was constructed with an angle resolution of 1°. The evolution of the droplet shape was determined with a time resolution of 0.04 s. The quantitative results are compared with other wetting‐reaction systems. In particular, it is demonstrated that the droplet has a spherical‐cup shape during the entire wetting‐reaction process.
Ectopic Expression of the CRF‐binding Protein: Minor Impact on HPA Axis Regulation but Induction of Sexually Dimorphic Weight Gain
Authors: Lovejoy  , Aubry  , Turnbull  , Sutton  , Potter  , Yehling  , Rivier  , Vale
Published: March 2003

Corticotrophin‐releasing factor (CRF) and urocortin possess a high‐affinity binding protein. Although the CRF binding protein (BP) can sequester these ligands and inhibit their activity, the endogenous activity of this protein is not understood. Therefore, transgenic mouse lines that over‐express the CRF‐BP were created. The transgene was constructed by ligating rat CRF‐BP cDNA (1.1 kb) between a mouse metallothionein‐I promoter (1.8 kb) and a nonfunctional human growth hormone gene sequence (2.1 kb) in a modified pBR322 plasmid and microinjecting the transgene into C57BL/6×SJL hybrid ova. The transgene was expressed in 50% in both male and female progeny. All transgenic lines were maintained by crossing transgenic animals with wild‐type C57BL/6 mates. Reverse‐transcriptase (RT) PCR of the CRF‐BP transgene showed that it is widely expressed not only in the brain and pituitary, but also peripheral tissues including the liver, kidney and spleen. Transgenic animals of both sexes showed significant increases in weight gain as established by analysis of variance; however, the weight gain profiles for each sex were distinct. High levels of circulating CRF‐BP were detected in the transgenic animals, but the basal ACTH and corticosterone levels were not significantly decreased compared to wild‐type littermates. The hypothalamo–pituitary–adrenal (HPA) axis was stimulated by systemic inflammation induced with lipopolysaccharide (LPS). An expected increase in transgene expression was observed and was accompanied by a significant attenuation of ACTH secretion at 3 h after LPS injection in the transgenic males but not the females. These data suggest that HPA axis regulation is significantly affected only with very high circulating levels of CRF‐BP. Moreover, this work supports previous studies that implicate CRF and urocortin in the regulation of appetite and the binding protein expression may play a sexually dimorphic role in regulating this and other responses.
Thyroid Hormones and Estrogen Affect Oxytocin Gene Expression in Hypothalamic Neurons
Authors: Dellovade Tammy L. , Zhu Yuan‐Shan , Pfaff Donald W.
Published: March 2003

The oxytocin (OT) gene promoter has a composite hormone response element, such that several members of the steroid/thyroid hormone superfamily of nuclear receptors can interact at this response element in vitro. To investigate this in brain tissue, parallel to foregoing behavioural experiments, we used in situ hybridization histochemistry to seek interactions between estrogen and thyroid hormones on OT mRNA in the hypothalamus. In ovariectomized (OVX) rats, high doses of triiodothyronine (T3) elevated OT mRNA levels in the paraventricular (PVN) nucleus, while treatment with estradiol benzoate (EB) alone had no significant effect. In contrast, animals that were thyroidectomized (TX) in addition to OVX had dramatically elevated levels of OT gene expression in the PVN following EB treatment. That is, endogenous thyroid hormones interfered with EB‐induction of gene expression. Moreover, in both OVX and TX/OVX animals, OT gene expression was reduced to values equivalent to controls when T3 was given together with EB. Particular subdivisions of the PVN responded differentially to T3 and EB treatment, demonstrating marked heterogeneity of OT‐containing neurons in this nucleus. Thus, parallel to and perhaps related to the manner in which thyroid hormones reduced estrogen‐stimulated behaviour, endogenous or exogenous thyroid hormones interfered with estrogen stimulation of OT mRNA. These data demonstrate competition between nuclear proteins, transcription factors, in hypothalamic neurons.
Leptin Receptor and Neuropeptide Y Gene Expression in the Sheep Brain
Authors: Williams  , Adam  , Mercer  , Moar  , Slater  , Hunter  , Findlay  , Hoggard
Published: March 2003

Leptin, a protein secretory product of adipocytes, is important in appetite control, energy balance and reproduction. In rodents, the physiological effects of leptin are centrally mediated, in part via the neuropeptide Y (NPY) system in the hypothalamus. The role of leptin in ruminants, where appropriate nutrition and reproductive status are of major economic concern, is largely unknown. To elucidate the function of leptin in sheep we have investigated putative sites of action for leptin in the brain and pituitary gland using both in‐situ hybridization to detect expression of the signalling form of the leptin receptor (OB‐Rb) and in‐vitro autoradiography using (125I)leptin to detect sites of specific leptin binding. OB‐Rb gene expression occurred in the hippocampus, cerebral cortex, preoptic area, stria terminalis and choroid plexus, and within the hypothalamus in the paraventricular (PVN), ventromedial (VHM) and arcuate (ARC) nuclei. OB‐Rb gene expression in the ovine pituitary gland was not detected by in‐situ hybridization. Sites of OB‐Rb and NPY gene expression were compared using both in‐situ hybridization on adjacent sections containing the arcuate and ventromedial nuclei, and dual in‐situ hybridization on sections containing these areas. In serial sections, OB‐Rb expression was found to correspond closely with that of NPY over the arcuate nuclei. Using dual in‐situ hybridization, NPY expressing neurones in the arcuate nuclei were also positive for OB‐Rb gene expression. Therefore, it appears that leptin may partly act via OB‐Rb located on NPY neurones in the sheep hypothalamus as in the rodent.
Differential Regulation of Hypothalamic Tuberoinfundibular Dopamine Neurones in Two Dwarf Rat Models with Contrasting Changes in Pituitary Prolactin
Authors: Thomas  , Phelps  , Robinson
Published: March 2003

In transgenic growth‐retarded (Tgr) rats, expression of human growth hormone (hGH) is targeted to hypothalamic GH‐releasing hormone (GHRH) neurones. In these rats, GHRH is reduced and somatostatin expression is increased, resulting in secondary GH deficiency and dwarfism. Tgr rats also show reduced pituitary prolactin (PRL), which may reflect an additional lactogenic feedback action of the hGH transgene, analogous to that in mice transgenic for peripheral hGH which show enhanced dopamine (DA) and tyrosine hydroxylase (TH) expression in the hypothalamic tuberoinfundibular dopaminergic (TIDA) neurones that inhibit PRL secretion. The present study examined DA histofluorescence and TH immunoreactivity in Tgr rats, and also in dw/dw rats, a dwarf strain with primary pituitary GH but not PRL deficiency. Radioimmunoassay confirmed a significant decrease in total pituitary PRL content in Tgr rats, but showed a marked increase in total pituitary PRL in dw/dw rats. Despite their PRL deficiency, Tgr rats showed qualitatively increased TIDA histofluorescence and TH immunoreactivity compared with AS control rats, though the total number of detectable TH‐positive TIDA neurones was similar for Tgr and AS. In contrast, dw/dw rats showed increased numbers of TH‐immunoreactive TIDA neurones whilst TIDA fluorescence was unchanged, and these findings were not affected in dw/dw rats given bovine GH (200 μg/d s.c. for 7 d). These results suggest that reduced PRL in Tgr rats is due to a local lactogenic feedback effect of hGH to stimulate TIDA neurones. The complex changes in TIDA neurones probably reflect a combination of increased lactogenic feedback in Tgr rats, with an increased (Tgr) or decreased (dw/dw) somatogenic feedback on GHRH neurones, some of which coexpress TH. Thus, the unchanged number of TIDA neurones in Tgr rats may result from hGH stimulation of TH and DA, but a reduction in GHRH‐producing cells, whereas increased TIDA neurones in dw/dw rats suggests a stimulation by endogenous PRL with an increased GHRH cell complement due to GH deficiency. These findings therefore indicate that differences in lactogenic feedback in these dwarf rat models are reflected in marked differences in their hypothalamic TIDA neurones.
Adrenocorticotropic Hormone Secretion in Rats Induced by Stimulation with Serotonergic Compounds
Authors: Jørgensen  , Knigge  , Kjær  , Warberg
Published: March 2003

The serotonin receptors involved in the secretion of adrenocorticotropin hormone (ACTH) were investigated in conscious adult male rats. Administration of serotonin (5‐HT), 5‐hydroxytryptophan (5‐HTP) in combination with the serotonin reuptake inhibitor fluoxetine (Flx), or of the 5‐HT agonists 8‐OH‐DPAT (5‐HT1A), 5‐carboxamido‐tryptamine (5‐HT1A+1B+5A+7), RU 24969 (5‐HT1B+1A), DOI (5‐HT2A+2C), S‐α‐methyl‐5‐HT (5‐HT2A+2B+2C), MK212 (5‐HT2B+2C), or methyl‐chlorophenyl‐piperazine (5‐HT2A+2C) dose‐dependently stimulated ACTH secretion. The 5‐HT3 agonist 2‐methyl‐5‐HT had no effect. Administration of a 5‐HT1 agonist in combination with any of the 5‐HT2 agonists DOI, S‐α‐methyl‐5‐HT or MK212 had an additive effect on the plasma concentration of ACTH. The ACTH stimulating effect of each of the 5‐HT agonists was inhibited by pretreatment with antagonists with corresponding 5‐HT receptor affinity. The ACTH response to 5‐HT or 5‐HTP/Flx was inhibited by injection with the 5‐HT1A+2A+2C+5A+7 antagonist methysergide, the 5‐HT2A antagonist ketanserine and the 5‐HT2C+2A antagonist LY 53857. The 5‐HT1A antagonist WAY 100635 enhanced 5‐HT‐ and 5‐HTP/Flx‐induced ACTH secretion, suggesting a presynaptic 5‐HT1A autoreceptor effect of the drug. The 5‐HT3 antagonist ondansetrone had no effect on the either of the 5‐HT agonists. The 5‐HT3+4 antagonist tropisetrone attenuated the effect of 5‐HTP/Flx, which may suggest a stimulation of ACTH secretion via 5‐HT4 receptors. It is concluded that 5‐HT1A, 5‐HT2A+2C, and to a lesser extent 5‐HT1B receptors, but not 5‐HT3 receptors are involved in the effects of serotonin agonists on ACTH secretion. Furthermore, an involvement of the 5‐HT5A and the 5‐HT7 receptor is possible.
Characterization of the Insulin‐Like Growth Factor Axis in the Human Thymus
Authors: Kecha  , Martens  , Franchimont  , Achour  , Hazée‐Hagelstein  , Charlet‐Renard  , Geenen  , Winkler
Published: March 2003

The components of the insulin‐like growth factor (IGF) axis have been investigated in the normal human thymus. Using ribonuclease protection assays (RPA), IGF‐II transcripts were detected in the normal human thymus. By reverse transcriptase polymerase chain reaction (RT‐PCR) analyses, promoters P3 and P4 were found to be active in the transcription of IGF2 gene within human thymic epithelial cells (TEC). No IGF‐II mRNA could be detected in human lymphoid Jurkat T cells with 30 cycles of RT‐PCR. By Northern blot analyses, IGFBP‐2 to ‐6 (but not IGFBP‐1) were found to be expressed in TEC with a predominance of IGFBP‐4. Interestingly, Jurkat T cells only express IGFBP‐2 but at high levels. The type 1 IGF receptor was detected in Jurkat T cells but not in human TEC. The identification of the components of the IGF axis within separate compartments of the human thymus adds further evidence for a role of this axis in the control of T‐cell development. The precise influence of thymic IGF axis upon T‐cell differentiation and immunological self‐tolerance however needs to be further investigated.
The Variability of Basal Action Potential Firing Is Positively Correlated with Bursting in Hypothalamic Oxytocin Neurones
Authors: Brown D. , Fontanaud P. , Moos F. C.
Published: March 2003

Magnocellular oxytocin neurones are proposed as a suitable system for studying the mechanisms involved in the regulation of neuronal bursting activity. They display high frequency (50 sp./s) bursts of spikes (approximately every 300 s), in response to specific stimuli, which are superimposed on a variable level of basal activity and are tightly co‐ordinated as a result of network interactions. The relationship between the strength of the bursting activity (as quantified by burst amplitude and interburst interval) and the characteristics of the interburst basal activity were assessed. During control conditions, mean basal activity and variability of firing increased just before bursts. During experimental conditions leading to burst facilitation, burst amplitude increased and interburst interval decreased while a sustained increase in mean firing rate occurred. Variability of firing (measured by both the standard deviation of firing rate, and the index of dispersion which corrected this standard deviation for differences in mean firing rate), increased demonstrating an increase in spike clustering greater than expected as a result of increased basal activity. When bursting was restrained (i.e. interburst interval increased), mean basal activity increased substantially, but index of dispersion decreased. A narrowing of the interspike interval distribution occurred, indicating increased regularity of firing. The aspect of basal activity most strongly correlated with bursting was variability of firing rate. The strongest correlate of burst amplitude was the standard deviation of mean firing rate, whereas the strongest and most consistent correlate of interburst interval was the index of dispersion. In conclusion, bursting behaviour is most strongly related to the irregularity rather than the level of basal activity.
Effects of Adrenalectomy and of Mineralocorticoid Receptor/Glucocorticoid Receptor Ligands in Female Brown Norway and Fischer 344 Rats and F1 Hybrids
Authors: Marissal‐Arvy N. , Mormède P.
Published: March 2003

Our previous studies suggested that the mineralocorticoid receptor (MR) of Brown Norway (BN) male rats is active independently of the presence of its ligands (i.e. constitutively active), and that glucocorticoid receptor (GR)‐mediated mechanisms are more efficient in BN than in Fischer 344 (F344) male rats. Such functional differences in corticosteroid receptors led us to compare the effect of adrenalectomy (ADX) and MR/GR‐mediated actions (treatments with deoxycorticosterone, DOC and RU 28362, respectively) on female rats from both strains, and, within the framework of a genetic study, to investigate how these differences were inherited in rats of the first generation (F1) born from the crossbreeding between BN and F344 inbred rats. This study extends our previous hypotheses of a constitutive activation of MR and of a greater efficiency of GR in males to females of the BN strain. In both strains, female rats were less sensitive to ADX and to treatments with DOC or RU 28362 than males. Globally, F1 hybrid BN×F344 rats inherited the functional characteristics of MR and GR of BN rats.
Ontogeny of Plurihormonal Cells in the Anterior Pituitary of the Mouse, as Studied by Means of Hormone mRNA Detection in Single Cells
Authors: Seuntjens E. , Hauspie A. , Vankelecom H. , Denef C.
Published: March 2003

The expression of mRNA of growth hormone (GH), prolactin (PRL), pro‐opiomelanocortin (POMC) and the common glycoprotein hormone α‐subunit (αGSU) was studied by means of single cell reverse transcriptase‐polymerase chain reaction in male mouse pituitary cells at key time points of fetal and postnatal development: embryonic day 16 (E16); postnatal day 1 (P1) and young‐adult age (P38). At E16, the hormone mRNAs examined were detectable, although only in 44% of total cells. Most of the hormone‐positive cells expressed only one of the tested hormone mRNAs (monohormonal) but 14% of them contained more than one hormone mRNA (plurihormonal cells). Combinations of GH mRNA with PRL mRNA, of αGSU mRNA with GH and/or PRL mRNA and of POMC mRNA with GH and/or PRL mRNA or αGSU mRNA were found. As expected, the proportion of hormone‐positive cells rose as the mouse aged. The proportions of plurihormonal cells followed a developmental pattern independent of that of monohormonal cells and characteristic for each hormone mRNA examined. Cells coexpressing POMC mRNA with GH or PRL mRNA significantly rose in proportion between E16 and P1, while the proportion of cells coexpressing GH and PRL mRNA markedly increased between P1 and P38. The occurrence of cells displaying combined expression of αGSU mRNA with GH and/or PRL mRNA did not significantly change during development. Remarkably, the population of cells expressing PRL mRNA only, was larger at E16 than at P1 and expanded again thereafter. In conclusion, the normal mouse pituitary develops a cell population that is capable of expressing multiple hormone mRNAs, thereby combining typical phenotypes of different cell lineages. These plurihormonal cells are already present during embryonic life. This population is of potential physiological relevance because development‐related factors appear to determine which hormone mRNAs are preferentially coexpressed. Coexpression of multiple hormone mRNAs may represent a mechanism to respond to temporally increased endocrine demands. The data also suggest that the control of combined hormone expression is different from that of single hormone expression, raising questions about the current view on pituitary cell lineage specifications.
Annexin‐1 (Lipocortin‐1)‐Immunoreactivity in the Folliculo‐Stellate Cells of Rat Anterior Pituitary: The Effect of Adrenalectomy and Corticosterone Treatment on Its Subcellular Distribution
Authors: Ozawa H. , Miyachi M. , Ochiai I. , Tsuchiya S. , Morris J. F. , Kawata M.
Published: March 2003

In the pituitary gland, annexin‐1 (lipocortin‐1) located in folliculo‐stellate (FS) cells has been advocated as one of the candidates for paracrine agents produced by FS cells that modulate the release of pituitary hormones. However, the expression and distribution pattern of annexin‐1 in FS cells under different circulating corticosteroid conditions has not been examined. Thus, by means of pre‐embedding immunoelectron microscopy, we investigated the expression of annexin‐1 in FS cells under different corticosteroid conditions. Annexin‐1‐immunoreactivity was observed in the cytoplasm; especially intense immunoreactivity was detected in the follicle surface of FS cells under control conditions. After adrenalectomy, annexin‐1‐immunoreactivity almost disappeared, but the immunoreactivity recovered with corticosterone replacement. The expression of glucocorticoid receptor immunoreactivity in the nucleus of FS cells also showed a similar pattern to annexin‐1 associated with the changes in the corticosteroid conditions. However, S‐100 immunoreactivity, a marker for FS cells, was not changed whatever the corticosteroid conditions. These results confirm that glucocorticoids regulate the annexin‐1 expression and demonstrate the translocation of annexin‐1 from intracellular to pericellular sites in the FS cells of the rat anterior pituitary gland.
Surface EMG activity of the masseter muscle in denture wearers during chewing of hard and soft food
Authors: Karkazis  , Kossioni
Published: March 2003

Previous studies mainly on dentate subjects, have clearly shown that food texture affects the various chewing parameters. The purpose of this investigation was to study the influence of food texture on the surface electromyographic (EMG) activity of the masseter muscle in a sample of denture wearers. Nine experienced denture wearers (mean age of 68·7 years) with clinically satisfactory dentures consented to participate in this study. Carrots and peeled apples cut into equally sized pieces were choosen as representing a hard and a soft food respectively. The parameters studied from the raw and integrated EMG recordings were: chewing rate, mean peak RMS activity, chewing cycle and chewing burst duration and relative contraction period. The findings were in line with those earlier reported on dentate subjects, in that harder foods require higher chewing rates, higher electrical activity of the masseter muscle and higher relative contraction periods, accompanied by shorter cycle durations. Most of these differences were statistically significant (P < 0·05) as tested by paired t‐test. Moreover a strong inverse correlation was found between chewing rate and cycle duration (r = –0.92, P < 0·05). We concluded that the texture of food has an obvious effect on all the studied parameters of EMG activity, and that those adjustments to food consistency are probably due to a combined powerfull peripheral input mediated through receptors, other than the periodontal ones.
In vitro adherence of Streptococcus constellatus to dense hydroxyapatite and titanium
Authors: Ichikawa  , Hirota  , Kanitani  , Miyake  , Matsumoto
Published: March 2003

Bacterial adherence to dense hydroxyapatite (HA) and titanium (Ti) rods was examined in vitro using Streptococcus constellatus ATCC27832. Streptoccus constellatus is associated with dental abscess and was isolated from the peri‐implantitis. The dense HA was etched with 5% hydrofluoric acid for 0, 10, 20, 30, 40, and 50 s Adherence to the untreated dense HA was twice as high as the adherence to the Ti. The adherence to saliva‐treated Ti was 13% higher than that to untreated Ti. The adherence was increased by acid‐treatment of the dense HA, following a sigmoid curve from 20 to 50 s of treatment time. The dense HA has the capacity to receive more bacterial adherence than Ti and furthermore, the etched dense HA becomes more adherent.
Comparison of marginal sealing ability of new generation bonding systems
Authors: Yap A. U. J. , Ho K. S. , Wong K. M.
Published: March 2003

The purpose of this in vitro study was to evaluate the enamel and dentine marginal sealing ability of four new generation composite bonding systems. Two Class V preparations, which were solely in enamel and dentine/cementum, were made on the buccal surfaces of 96 freshly extracted molar teeth. The teeth were randomly divided into four groups of 24 and restored with composite resin (Silux Plus®) utilizing the following bonding systems: Scotchbond Multi‐purpose® (SB), Fuji Bond LC® (FB), Prime & Bond 2·0® (PB) and Bisco One‐step® (BC). The restorations were finished immediately after photo‐polymerization and stored in saline at 37 °C for 1 week. Half of the specimens in each group were then thermally stressed for 500 cycles. All restorations were then subjected to dye penetration testing, sectioned and scored. Results revealed no statistically significant difference (P < 0·05) in dye penetration scores for the different bonding systems with the exception of leakage at the dentine margins of thermally stressed specimens where FB exhibited significantly better sealing ability compared with the other bonding systems and BC exhibited significantly less leakage than PB. The marginal seal of ‘one‐step’ (PB and BC) and resin‐modified glass–ionomer (FB) bonding systems appear to be as effective as ‘two step’ systems like SB. Thermal stresses had some influence on marginal seal but this was both product and tissue specific.
Factors influencing dental students to attend for eye examination
Authors: Chadwick R. G.
Published: March 2003

This investigation sought to determine those factors influencing dental students to attend for eye examination together with the frequency of such tests and level of eyesight correction. A questionnaire was constructed and circulated to all clinical dental students attending lectures and practical classes in Dundee over a 1‐week period. This ascertained the age and sex of the respondents and gathered information on what had prompted each individual to attend for eye examination. The knowledge of any visual problems and their correction was also ascertained. All 114 questionnaires that were distributed were completed. The mean elapsed time interval since the last eye examinations was 1·81 (standard deviation = 1·19) years. The frequency of attendance was not affected by gender. Those who had had their eyesight corrected were significantly ( P < 0·01) more likely to attend for examination every 2 years than those without correction. Good eyesight is important for the practice of dentistry and, although this is well recognized, it is apparent that the need for regular testing has not been understood by all. Strenuous efforts should be made to ensure that this message is impressed upon dental undergraduates from an early stage in their careers so that they may undergo screening every 2 years throughout their professional careers.
Studies on optical properties of two commercial visible‐light‐cured composite resins by diffuse reflectance measurements
Authors: Taira M. , Okazaki M. , Takahashi J.
Published: March 2003

Two commercial visible‐light (VL)‐cured composite resins were examined for their optical properties by diffuse reflectance measurements in VL spectrum and Kubelka–Munk's theory. Cured Silux Plus® displayed diffuse reflectance similar to that of cured Z100®, although uncured Silux Plus® showed diffuse reflectance less than that of uncured Z100®. By Kubelka–Munk's analyses, two optical constants of the composites at eight wavelengths such as absorption and scattering coefficients were calculated using the difference in diffuse reflectance of the composites backed between white and black standards. Upon curing, the two optical constants of the composites significantly altered especially in the shorter wavelengths. By lowering the wavelength, two optical constants of the composites tended to increase, giving rise to less light reflection and transmission. The theoretical optical transmittance of the composites was expressed in terms of hyperbolic functions of thickness of the composites at eight wavelengths in VL, dependent upon the two optical constants. The actual optical transmittance of 1 mm composites were fairly comparative with the theoretical values at 1 mm. The depth of cure of the two composites matched well with the thickness of the uncured composites which yielded the minimum theoretical optical transmittance in the wavelength region of 400–500 nm.
The relationship between frontal facial morphology and occlusal force in orthodontic patients with temporomandibular disorder
Authors: Yamada K. , Hanada K. , Sultana M. H. , Kohno S. , Yamada Y.
Published: March 2003

The aim of this study was to investigate the relation between frontal craniofacial morphology and the distribution of occlusal force in orthodontic patients with and without TMD. Experimental data were obtained from 45 female orthodontic patients (TMD‐free group: 22 subjects; TMD group: 23 subjects) using the pressure‐sensitive sheet. The following results were obtained: (1) There were significant differences in the gonial angle width and the mandibular deviation of the postero‐anterior cephalogram between the two groups.  (2) There were significant differences in occlusal force, occlusal contact area and average occlusal pressure between the two groups.  (3) On the relation between the frontal craniofacial morphology and the occlusal data, the asymmetry indices of occlusal force and occlusal contact area showed significant positive correlations to the mandibular deviation and the ratios of maxillary and gonial angle widths in the TMD group. The TMD‐free group showed the smaller mandibular deviation and the smaller asymmetry indices of occlusal force and occlusal contact area than those in the TMD group.  It could be concluded that orthodontic patients with TMD may have not only the morphological disharmony but also the imbalance of occlusal force.
Fluoride ion diffusion from a glass–ionomer cement
Authors: Lee S.‐Y. , Dong D.‐R. , Huang H.‐M. , Shih Y.‐H.
Published: March 2003

The aims of this study were to observe the release of fluoride ions (F−) from GC‐Fuji Lining‐LC® glass–ionomer cement, to assess the diffusion process, and to measure fluoride diffusivity (D) in the set cement. Specimens of various dimensions and shapes, ranging from discs to cylindrical rods, were fabricated for both open and embedded modes of testing. In the open mode studies, specimens with different surface to volume ratios were selected and immersed in 37 °C distilled water. In the embedded mode studies, only one diametral surface of the rod‐shaped specimens of different lengths and diameters was exposed. F− concentration was measured using a fluoride electrode. The storage solution was analysed at predetermined intervals hourly, daily, and weekly (up to 10 weeks). Immediately after each sampling, the old storage solution was discarded and replaced with new distilled water. F− release from the set cements was detectable (0·4–3·8 ppm, varied with sample geometry), even after a 10‐week sampling interval. F− release was greater in ground set cements (0.37 ppm/mg powder) than in control samples of unmixed powder (0.01 ppm/mg powder) immersed for 1 h. Two mechanisms for F− release were proposed. One was short‐term and involved rapid dissolution from the cement surface. The other was more gradual and resulted in the sustained diffusion of ions through the bulk cement, which can be modelled by applying a mathematical technique known as separation of variables to Fick's Second Law of Diffusion. The mean D of F− in embedded set cements of glass–ionomer was (1·4±0·5)×10−11 cm2/s, with higher apparent D observed in open mode samples [(7·6±1·4)×10−11 cm2/s].
In vitroassessment of corrosive properties of titanium as a biomaterial
Authors: Koike M. , Fujii H.
Published: March 2003

Titanium (Ti) is thought to be a highly biocompatible material, and its clinical applications are becoming increasingly frequent. However, there have recently been some clinical papers reporting hypersensitivity and allergic reactions to Ti. The purpose of this study was to assess the corrosive properties of Ti in the intra‐oral environmentin vitro. Cast pure Ti specimens were immersed in artificial saliva, physiological saline solution, and 128 mmol L−1of lactic, formic and acetic acids for 3 weeks at 37 °C with shaking. The colour, weight, surface morphologies and chemical binding state of specimens were observed before and after immersion. Marked discoloration was recognized on the surface of specimens immersed in formic acid, and a significant difference was found between the immersion solutions. Weight changes also varied with solutions; a tendency to increase in formic acid and to decrease in lactic acid. A slight loss was observed in specimens immersed in lactic acid and artificial saliva. The oxide layer composed mainly of Ti‐oxide on the surface of the immersed specimens was thinnest in lactic acid, and thickest in formic acid. The present study indicates that both hydrogen evolution type and oxygen diffusion type corrosion on Ti surfaces are possible in the living body. (Our results also confirm some clinical studies reporting Ti accumulation in surrounding tissues and Ti causing allergic reactions.)
Can a prosthesis cause psychological disturbances?
Authors: Branchi R. , Boddi V. , Corti D. , Hardoy M. J.
Published: March 2003

This study has the aim of evaluating whether a very simplified, fixed prosthesis and correction (single crown or small bridge) can be the cause of psychological problems in some patients. The tests utilised are, STAI‐Y (STAI‐S for state anxiety, STAI‐T for trait anxiety), BDI for depression, SP‐it for stress events, SDS for somatoform disorders, The tests were given to patients at the first examination (t0) and at the check‐up (t1) 1 month after the definitive prosthesis was cemented. The results have shown that somatic preoccupations, in some cases, increased from t0 to t1. It is then right that we ask ourselves the following: if the prosthesis were to be very complicated (implants, dentures), what would happen to the patient from a psychological standpoint?
A physiotherapeutic approach to craniomandibular disorders: a case report
Authors: Bevilaqua‐Grosso D. , Monteiro‐Pedro V. , Guirro R. R. De Jesus , Bérzin F.
Published: March 2003

This is a case report of a 19‐year‐old female who presented with a unilateral weakness of the right masseter muscle evidenced by electromyographic examination. The presence of a mandibular deviation to the right during opening because of this weakness was treated with neuromuscular electrical stimulation (NMES). After the physiotherapeutic treatment, the electrical activity of the right masseter muscle increased during function and the mandibular deviation disappeared. Electromyography (EMG) can have a useful role in the determination of the muscular profile, and for evaluating therapeutics.
Dentine hypersensitivity: the effects of brushing toothpaste on etched and unetched dentine in vitro
Authors: West N. X. , Hughes J. A. , Addy M.
Published: March 2003

Although many people have exposed dentine, only a percentage exhibit symptoms of dentine hypersensitivity. This has been ascribed to opening and closing of the dentinal tubules by for example, smear layer changes or tubular occlusion. The aims of this study were to examine the surface morphological changes of etched and unetched dentine in vitro, attributed to the effects of toothbrushing with and without toothpastes designed for the alleviation of dentine hypersensitivity. A total of 96 etched and 96 unetched human dentine specimens were brushed with various toothpastes and water for 1, 2, 5 or 10‐min periods in a toothbrushing machine and subsequently examined under scanning electron microscopy for surface changes. Analyses of brushed etched specimens demonstrated that time and treatment were significant variables (P < 0·05) for tubule occlusion. Further, the interaction between time and treatment was significant (P < 0·05). The artificial silica based paste was significantly better for all time intervals at occluding the dentine tubules. All toothpastes investigated caused dynamic changes to the smear layer of the unetched dentine, opening tubules. However, the artificial silica based paste resulted in occluded rather than patent tubules. All of the pastes evaluated had the capacity to remove the smear layer but some could then occlude tubules through the contained abrasives.
In vitro study of fracture strength and marginal adaptation of polyethylene‐fibre‐reinforced‐composite versus glass‐fibre‐reinforced‐composite fixed partial dentures
Authors: Kolbeck C. , Rosentritt M. , Behr M. , Lang R. , Handel G.
Published: March 2003

This in vitro study was carried out in order to estimate the clinical usability of adhesively luted three‐unit posterior fixed partial dentures (FPD) made of a polyethylene‐fibre‐reinforced‐composite system (PFRC) in comparison with a glass‐fibre‐reinforced‐composite system (GFRC). Therefore the fracture strength and marginal adaptation were examined. A total of 16 FPDs of each material combination were manufactured and adhesively luted to human molars. Before and after an artificial ageing process by thermal cycling and mechanical loading (TCML) the quality of the marginal adaptation was examined by evaluating epoxy replicas in a scanning electron microscope (SEM). After TCML the fracture strength of eight FPDs of each series was tested by mechanical loading them to failure. With the remaining eight FPDs the quality of deeper layers of the luting was examined with a dye penetration technique. The calculated median fracture strength values (25/75% percentiles) were 830 N (643/982) for the PFRC and 884 N (684/1113) for the GFRC. The SEM analysis showed at least 80% of perfect marginal areas for both material combinations in dentine as well as in enamel before and after TCML. Looking at the cement–tooth interfaces the dye penetration technique showed statistically significant better results for the enamel finishing lines than for those in dentine. With finishing lines in dentine the two material combinations showed statistically significant differences for this interface. Fracture force results as well as marginal quality encourage further clinical investigations on both systems although the GFRC performed slightly better than the PFRC.
Magnetic resonance imaging findings of internal derangement in temporomandibular joints without a clinical diagnosis of temporomandibular disorder
Authors: Emshoff R. , Rudisch A. , Innerhofer K. , Brandlmaier I. , Moschen I. , Bertram S.
Published: March 2003

The purpose of this study was to assess the prevalences of magnetic resonance (MR) imaging findings of internal derangement (ID) in temporomandibular joints (TMJs) without a specific clinical diagnosis of temporomandibular disorder (TMD), and to investigate whether in this TMJ group the variable of pain may be linked to MR imaging findings of ID. The study comprised 109 patients, who were assigned a clinical uni‐ or bilateral TMJ‐related diagnosis of `absence of TMD'. Bilateral sagittal and coronal MR images were obtained subsequently to establish the prevalence of TMJ ID. An MR imaging diagnosis of ID was found in 99 (55·9%) of the 177 TMJs investigated. About 30·3% of the closed mouth‐related TMJ positions characterized by disc displacement presented with anterior disc displacement, while 27·3% had anterolateral and 25·3% anteromedial disc displacement. Analysis of the data revealed the presence of TMJ pain to be associated with significantly more MR imaging diagnoses of disc displacement without reduction than disc displacement with reduction (P < 0·05), while there was no significant difference in the prevalences of ID and those of absence of ID (P > 0·05). Using chi‐square analysis, no significant relationship was found between the presence of TMJ pain and the MR imaging diagnosis of TMJ ID (P=0·93). Use of the κ statistical test indicated poor diagnostic agreement between the presence of TMJ pain and the MR imaging diagnosis of ID (κ=0·01). The results suggest TMJs with a clinical diagnosis of `absence of TMD' to be associated with a high rate of IDs, while in these instances the clinical variable of TMJ pain may have no effect on prevalences of MR imaging diagnoses TMJ ID. The data confirm the aspect of clinical diagnostic criteria as an unreliable instrument in predicting MR imaging diagnoses of TMJ ID.
An index for analysing the stability of lateral excursions
Authors: Tsuruta J. , Mayanagi A. , Miura H. , Hasegawa S.
Published: March 2003

Five lateral excursions on both left and right sides of 20 healthy subjects were recorded by Gnatho‐hexagraph®, which was an opto‐electronic system with six degrees of freedom. The incisor point, the working condylar point (WCP) and the balancing condylar point (BCP) were analysed. When the incisor point moved 1, 2, 3, 4, 5 mm on its path, the incisor point and corresponding condylar points were analysed. The linear distances from the intercuspal position (ICP) to each analysed point at each analysed position were calculated as Linear distance. The distance between five lateral excursions in x, y, z, space coordinates at each analysed position of three analysed points were calculated as Dx, y, z, s. To evaluate the stability of lateral excursions, the Index S was defined as the equation (S=D/Linear distance * 100) and calculated. From the result of Index S, the WCP showed significantly less stability than the other two analysed points (P < 0·05). The incisor point showed best stability, especially in upper–lower direction. The BCP also showed good stability. Index S revealed the characteristic movement in x, y, z, space coordinates at each analysed point and it showed clearly the stability of lateral excursions.
Focal dystonia of the lateral pterygoid muscles treated with botulinum toxin
Authors: MOLLER E. , DALAGER T. , FUGLSANG‐FREDERIKSEN A. , PRYTZ S. , WERDELIN L. M. , BAKKE M.
Published: March 2003

Oromandibular dystonia (OD) is a movement disorder characterized by involuntary activity of the craniofacial muscles. The present study deals with dystonic activity in the lateral pterygoid muscles (LP) of two women causing mandibular overbite, tiredness in the face and chewing and speech difficulties in one (HN, 61 years). In the other (BS, 37 years) OD was characterized by irregular lateral and protrusive jaw movements with and without tooth contact and frequent bilateral headache.

By intra‐oral approach and without attempt to distinguish between the two heads the activity of LP was assessed by quantitative electromyography (EMG). Concentric needle electrodes were used for diagnosis and follow‐up, monopolar cannula electrodes for the EMG‐guided injection of botulinum toxin (Botox®, Allergan Inc., USA). In addition, activity in the temporal, masseter and digastric muscles was recorded with bipolar surface electrodes and mandibular movements were assessed graphically. Compared with reference values of postural activity, OD in both patients was associated with a marked increase in LP. Botox injections resulted in transient reduction of spontaneous and maximal activity, but it took two to three treatments with intervals of 3–4 months to obtain distinct subjective and clinical improvement. However, in HN followed for 18 months after breakthrough of treatment, the effect of the two latest injections lasted 8–9 months or three to four times longer than typical.

Using quantitative EMG to locate the abnormal activity and to guide injections, treatment of LP dystonia with botulinum toxin is effective and safe.