bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Nitric Oxide Synthase Inhibition on Fos Expression in the Hypothalamus of Female Rats Following Central Oxytocin and Systemic Urethane Administration
Authors: Popeski N. , Woodside B.
Published: March 2003

Three experiments were carried out to investigate the pattern of neuronal activation induced by central oxytocin administration and its modulation by nitric oxide (NO). First, we compared the induction of Fos‐like immunoreactivity (lir) in the supraoptic (SON) and paraventricular (PVN) nuclei and medial preoptic area (MPOA) after central oxytocin administration between nonlactating and lactating rats. Next, we investigated whether NO modulated Fos induction following central oxytocin administration using a nitric oxide synthase (NOS) inhibitor, Nω‐nitro‐l‐arginine methyl ester (l‐NAME). Finally, to determine whether the effects of NOS inhibition on Fos induction would generalize to stimuli other than oxytocin, we compared Fos‐lir in the SON and PVN of lactating and nonlactating rats following l‐NAME and urethane administration. In the first two experiments, oxytocin (50 ng in 2 µl) or vehicle was administered into the third ventricle. l‐NAME (50 mg/kg) was given by an intraperitoneal (i.p.) injection 30 min before oxytocin administration (experiment 2) or an i.p. injection of urethane (1.4 g/kg) (experiment 3). In all experiments, lactating rats were tested on day 12 or 13 postpartum and nonlactating females at least 11 days after surgery or the start of the experiment. Central oxytocin infusion induced Fos expression in the SON and PVN in lactating and nonlactating rats and in the MPOA and bed nucleus of the stria terminalis in lactating rats. Overall, lactating rats that received l‐NAME and oxytocin had a greater number of cells showing Fos‐lir in both the SON and PVN. Conversely, l‐NAME administration reduced Fos‐lir in the SON and PVN in oxytocin‐stimulated nonlactating rats. In urethane‐treated rats, l‐NAME administration did not change Fos‐lir in lactating rats but reduced Fos‐lir in nonlactating rats. These data suggest that the role of NO in modulating the activity of neurones in discrete nuclei in the hypothalamus varies across reproductive state and with the stimulus presented.
Bradykinin and Angiotensin II‐Induced [Ca2+]i Rise in Cultured Rat Pituitary Folliculo‐Stellate Cells
Authors: Sudo T. , Sakuma Y. , Kato M.
Published: March 2003

Folliculo‐stellate cells of the anterior pituitary are thought to modulate pituitary hormone secretion through a paracrine mechanism. Angiotensin II and pituitary adenylate cyclase‐activating polypeptide (PACAP) have previously been shown to increase the intracellular Ca2+ concentration ([Ca2+]i) of these cells. In the present study, we examined the effects of various peptides such as bradykinin, angiotensin II, endothelin‐1, PACAP, galanin and neurotensin by Ca2+‐imaging of folliculo‐stellate cells in primary culture. Bradykinin and angiotensin II increased [Ca2+]i in folliculo‐stellate cells. Both responses were completely suppressed by thapsigargin and were significantly suppressed by the phospholipase C inhibitor, U‐73122. Ryanodine did not significantly modify the responses. A B2 antagonist and angiotensin II receptor antagonist inhibited the response induced by bradykinin and angiotensin II, respectively. Endothelin‐1 and PACAP increased [Ca2+]i in fewer than 50% of folliculo‐stellate cells but galanin and neurotensin did not influence [Ca2+]i in any of the folliculo‐stellate cells tested. These results indicate that bradykinin and angiotensin II increase [Ca2+]i in folliculo‐stellate cells by activating phospholipase C through B2 receptor and AT1 receptor, respectively, and that endothelin‐1 and PACAP also increase [Ca2+]i in some folliculo‐stellate cells.
Intracerebroventricular Adrenomedullin Stimulates the Hypothalamic‐Pituitary‐Adrenal Axis, the Sympathetic Nervous System and Production of Hypothalamic Nitric Oxide
Authors: Shan J. , Krukoff T. L.
Published: March 2003

We tested the hypothesis that central adrenomedullin stimulates activity of the hypothalamic‐pituitary‐adrenal (HPA) axis and sympathetic output from the brain, and we assessed the effects of central adrenomedullin on the nitric oxide (NO) system in the brain. In conscious rats, intracerebroventricular (i.c.v.) injections of adrenomedullin (2 nmol/kg) increased arterial pressure and heart rate, with return to baseline values within 20 min and 65 min of injections, respectively. Adrenomedullin injections augmented expression of tyrosine hydroxylase mRNA in the locus coeruleus after 4 h. Plasma concentrations of adrenocorticotropic hormone, measured with radioimmunoassay, were also increased by adrenomedullin. i.c.v. Adrenomedullin stimulated Fos expression in neurones within autonomic centres including the paraventricular nucleus (PVN) of the hypothalamus, arcuate nucleus, locus coeruleus, nucleus of the tractus solitarius and area postrema. In the PVN, large proportions of corticotropin releasing factor‐ and NO‐producing neurones were activated (Fos positive). NO production, measured with nitrate/nitrite assays, was elevated in the hypothalamus, but not brainstem, of adrenomedullin‐treated rats compared to controls. We conclude that centrally administered adrenomedullin stimulates activity of the HPA axis, the sympathetic nervous system, and the hypothalamic NO system.
Long‐Term Undernutrition Followed by Short‐Term Refeeding Effects on the Corticotropin‐Releasing Hormone Containing Neurones in the Paraventricular Nucleus: An Immunohistochemical Study in Sheep
Authors: Chaillou E. , Baumont R. , Tramu G. , Tillet Y.
Published: March 2003

The effect of nutritional level on the immunoreactivity of corticotropin‐releasing hormone (CRH) in neurones of the hypothalamic paraventricular nucleus was described in sheep, a ruminant, whose feeding strategy differs from that of monogastric species. Two groups of ewes were underfed (40%), or fed at maintenance (100%) for 167 days, after which one‐half of each group was killed or ad libitum refed (at least 150% of maintenance) for 4 days before killing. The presence of CRH in the paraventricular nucleus was examined by immunohistochemistry. The number of CRH immunoreactive neurones was increased in underfed ewes, but without modification of the plasma concentration of cortisol, indicating that the rise of CRH was not released in the portal blood nor linked to the pituitary‐adrenal axis. Refeeding did not modify significantly the number of CRH immunoreactive neurones in the nucleus although these neurones were increased, only in refed ewes that were previously underfed. These data differ from those for rats and mice where CRH expression is decreased or not modified by underfeeding which could reflect different effects of undernutrition on CRH immunoreactive neurones in monogastric compared to ruminants species.
Comparison of Somatostatin Receptor Expression in Human Gliomas and Medulloblastomas
Authors: Cervera P. , Videau C. , Viollet C. , Petrucci C. , Lacombe J. , Winsky‐Sommerer R. , Csaba Z. , Helboe L. , Daumas‐Duport C. , Reubi J. C. , Epelbaum J.
Published: March 2003

The expression of the five somatostatin receptor subtypes, sst1–5 was compared on tissue containing glial tumours (glioblastomas or oligodendrogliomas), medulloblastomas, and on normal human cortex. By semiquantitative reverse transcription coupled to polymerase chain reaction, the receptor expression profiles were high in cortex and in tissue containing oligodendrogliomas. It was moderate in medulloblastomas. Tissue containing glioblastomas displayed lower expression of somatostatin receptor subtypes, sst1 and sst3 being mostly expressed. By 125I‐Tyr0DTrp8 somatostatin‐14 or 125I‐Leu8DTrp22 Tyr25 somatostatin‐28 autoradiography combined with synaptophysin immunohistochemistry, it was possible to differentiate between isolated tumoral cell component infiltrating the cerebral parenchyma (cortex or white matter) and tumoral tissue (without residual parenchyma) in glioblastomas or oligodendrogliomas. Glial tumoral tissue per se presented few somatostatin receptors. By contrast, medulloblastoma tumoral cells exhibited numerous octreotide sensitive somatostatin receptors. sst2 immunocytochemistry demonstrated immunostaining of neuronal cells and neuropile; sst2 and sst3 immunostaining was identified on glioblastoma proliferating vessels endothelial cells and on medulloblastomas tumoral cells. Faint sst2 immunostaining among glial tumoral cells was due to microglia, while glioma cells did not significantly stain. In summary, medulloblastoma tumoral cells express sst2/sst3 receptors at a high level while glioma cells do not. In gliomas, sst expression is restricted to endothelial cells on proliferating vessels (displaying both sst2 and sst3 receptors), including parenchyma and reactive microglia (only sst2). The differential expression of sst2/sst3 receptors on gliomas and medulloblastomas has implications for the therapy of these tumours.
Progestin Receptor Immunoreactivity Within Steroid‐Responsive Vasopressin‐Immunoreactive Cells in the Male and Female Rat Brain
Authors: Auger C. J. , De Vries G. J.
Published: March 2003

Progestin receptor immunoreactivity is found in the same regions of the bed nucleus of stria terminalis (BST) and centromedial amygdala (CMA) as steroid‐responsive vasopressin immunoreactive (AVP‐ir) cells. To test whether AVP‐ir cells express progestin receptors, brains of male rats were stained immunocytochemically for arginine vasopressin as well as progestin receptors. In BST and CMA, over 95% of AVP‐ir cells contained progestin receptor immunoreactivity. In contrast, none of the AVP‐ir cells in the suprachiasmatic, supraoptic and paraventricular nuclei expressed progestin receptor immunoreactivity. To study whether progestin receptor expression in AVP‐ir cells in the BST and CMA is responsive to gonadal steroids, male and female rats were castrated and implanted with either empty capsules or capsules filled with testosterone or oestradiol, respectively. Ten days later, brains were processed for AVP and progestin receptor immunoreactivity. Although there was no effect of hormonal status on the percentage of colocalized cells, the level of progestin receptor immunoreactivity was higher in rats that received gonadal steroids than those that did not. The presence of progestin receptor immunoreactivity in steroid responsive AVP‐ir cells, and the responsiveness of this expression to gonadal hormones, is consistent with the possibility that the effects of gonadal steroids on AVP‐ir expression in the BST and CMA may be mediated at least in part by progestin receptors.
The Effect of Endotoxin Administration on the Secretory Dynamics of Oxytocin in Follicular Phase Mares: Relationship to Stress Axis Hormones
Authors: Alexander S. L. , Irvine C. H. G.
Published: March 2003

The primary aim of this study was to define the secretory dynamics of oxytocin and vasopressin in pituitary venous effluent from ambulatory horses during acute endotoxaemia, a stimulus that may release both hormones. Our secondary aim was to investigate the role of oxytocin in regulating adrenocorticotropic hormone (ACTH) secretion by comparing oxytocin, vasopressin, corticotropin‐releasing hormone (CRH) and ACTH secretory profiles during endotoxaemia and by monitoring the ACTH response to oxytocin administration. Pituitary venous blood was collected nonsurgically continuously and divided into 1‐min segments from eight follicular phase mares. Four mares were sampled for 30 min before and 3.5 h after receiving an i.v. infusion of bacterial endotoxin (TOX). Four control mares were sampled for 2.5 h without infusion of TOX. Another three follicular phase mares were given 5 U of oxytocin to replicate the peak response to TOX and pituitary blood collected every 1 min for 10 min before and 15 min after injection. Endotoxin raised the secretion rates of all hormones measured. All hormones were released episodically throughout the experiment, with TOX increasing the amplitude of peaks in each hormone. Peaks in oxytocin and vasopressin were coincident in each treated mare. Similarly, ACTH peaks were coincident with peaks of oxytocin and vasopressin in each treated mare, and with peaks of CRH in three mares. However, oxytocin administration did not affect ACTH secretion. We conclude that during endotoxaemia in horses: (i) oxytocin and vasopressin are secreted synchronously; (ii) oxytocin is unlikely to be acting as an ACTH secretagogue since inducing peak oxytocin concentrations observed during TOX does not raise ACTH; and therefore (iii) the close relationship between oxytocin and ACTH secretion is circumstantial and due to the fact that oxytocin secretion is concurrent with that of vasopressin, a proven ACTH secretagogue in horses.
Fasting Stimulates Tuberoinfundibular Dopaminergic Neuronal Activity and Inhibits Prolactin Secretion in Oestrogen‐Primed Ovariectomized Rats: Involvement of Orexin A and Neuropeptide Y
Authors: Hsueh Y.‐C. , Cheng S.‐M. , Pan J.‐T.
Published: March 2003

Fasting up‐regulates central orexigenic systems including orexin A and neuropeptide Y (NPY) and it also inhibits the secretion of prolactin. We hypothesized that fasting may act through orexin A and NPY to influence tuberoinfundibular dopaminergic (TIDA) neurones, the major regulator of prolactin secretion. The effects of orexin A and NPY on TIDA neuronal activity and prolactin secretion were determined in oestrogen‐primed ovariectomized rats, and the effects of fasting and the involvement of orexin A and NPY were tested. Orexin A, NPY and its analogs were administered through preimplanted intracerebroventricular (i.c.v.) cannulae. TIDA neuronal activity was determined by measuring concentrations of 3,4‐dihydroxyphenylacetic acid (DOPAC) or 3,4‐dihydroxyphenylalanine in the median eminence. i.c.v. injection of NPY (10 µg) or orexin A (1 µg) concomitantly increased median eminence DOPAC and decreased serum prolactin concentrations. The effect of NPY was mimicked by a Y1 receptor agonist at lower doses (0.1 and 1 µg) and no additive effect was observed when orexin A and the Y1 agaonist were coadministered. Moreover, a Y1 receptor antagonist, BIBP, not only blocked the effect of Y1 agaonist, but also that of orexin A. Treatment with BIBP alone decreased median eminence DOPAC and increased serum prolactin concentrations, indicating that endogenous NPY may play a role. Moreover, fasting for 48 h significantly increased TIDA neuronal activity, both in the morning and afternoon, and the effect was reversed by treatment with either BIBP or an antibody against orexin A. The findings support our hypothesis that fasting stimulates TIDA neuronal activity and inhibits prolactin secretion through up‐regulated central orexin A and NPY systems.
A Novel Mechanism for Endocrine‐Disrupting Effects of Polychlorinated Biphenyls: Direct Effects on Gonadotropin‐Releasing Hormone Neurones
Authors: Gore A. C. , Wu T. J. , Oung T. , Lee J. B. , Woller M. J.
Published: March 2003

Polychlorinated biphenyls (PCBs) cause abnormal development and physiology of the reproductive system. We hypothesized that these effects may be mediated, at least in part, by neuroendocrine cells in the hypothalamus that integrate inputs to and outputs from the central nervous system and reproductive systems. The effects of two PCB mixtures, Aroclor 1221 and Aroclor 1254, were tested on the hypothalamic GT1‐7 cells, which synthesize and secrete the key hypothalamic hormone, gonadotropin‐releasing hormone (GnRH). GT1‐7 cells were treated for 24 h in dose–response experiments and GnRH gene expression and release were quantified. Aroclor 1221 was stimulatory to GnRH gene expression, particularly at post‐transcriptional levels (GnRH cytoplasmic mRNA), and increased GnRH peptide levels, suggesting a post‐translational regulation of GnRH biosynthesis. It also caused a qualitative increase in GT1‐7 neurite outgrowth and cell confluency. Aroclor 1254 had very different effects from Aroclor 1221. It inhibited GnRH nuclear mRNA levels at high dosages, and stimulated GnRH mRNA at low doses, suggesting a post‐transcriptional mechanism of regulation. Aroclor 1254 did not alter GnRH peptide levels. Qualitatively, Aroclor 1254 caused a retraction of GT1‐7 cell processes and neurotoxicity at high dosages. In order to gauge the involvement of the oestrogen receptor in these responses, the oestrogen receptor antagonist, ICI 182,780 (ICI) was coadministered in other studies with the PCBs. While effects of Aroclor 1221 on GnRH gene expression were not blocked by ICI, its effects on GnRH peptide levels were blocked by ICI, indicating that some but not all of the effects of Aroclor 1221 are mediated by the classical oestrogen receptor α and/or β. The inhibitory effects of Aroclor 1254 on GnRH gene expression were not prevented by ICI, although ICI itself had stimulatory effects on GnRH gene expression that were blocked by cotreatment with Aroclor 1254. These results demonstrate a novel mechanism for effects of the two PCBs directly on GnRH gene expression, and indicate a hypothalamic level for endocrine disruption by these environmental toxicants.
Demonstration of Postsynaptic Receptor Plasticity in an Amphibian Neuroendocrine Interface
Authors: Jenks B. G. , Ouwens D. T. W. M. , Coolen M. W. , Roubos E. W. , Martens G. J. M.
Published: March 2003

Pituitary pars intermedia melanotrope cells are often used as a model to study mechanisms of neuroendocrine integration. In the amphibian Xenopus laevis, the synthesis and release of α‐melanophore‐stimulating hormone (α‐MSH) from these cells is a dynamic process dependent upon the colour of background. In animals on a black background, there is a higher level of synthesis and secretion of α‐MSH than in animals on a white background, and, consequently, there is skin darkening in animals on a black background. The melanotropes are innervated by hypothalamic neurones that produce neuropeptide Y (NPY), a peptide that inhibits α‐MSH secretion via the NPY Y1 receptor. The inhibitory neurones have a higher expression of NPY in animals adapted to a white background and both the size and the number of inhibitory synapses on the melanotrope cells are enhanced. The purpose of the present study was to determine if this presynaptic plasticity displayed by the inhibitory neurones is reciprocated by postsynaptic plasticity (i.e. if there is an enhanced expression of the Y1 receptor in melanotropes of animals adapted to a white background). For this purpose quantitative real‐time reverse transcriptase‐polymerase chain reaction was used to determine the level of Y1 receptor mRNA in melanotropes of animals undergoing the process of background adaptation. The results showed that there is a higher Y1 receptor mRNA expression in melanotropes of white‐adapted animals. We conclude that the inhibitory neuroendocrine interface in the Xenopus pars intermedia displays postsynaptic plasticity in response to changes of background colour. To our knowledge, this is the first demonstration of a physiological environmental change leading to changes in postsynaptic receptor expression in a fully identified vertebrate neuroendocrine reflex.
Oxytocin Inhibits Aggression in Female Syrian Hamsters
Authors: Harmon A. C. , Huhman K. L. , Moore T. O. , Albers H. E.
Published: March 2003

Dominant subordinate relationships are formed as the result of social conflict and are maintained at least in part by communication. At this time, little is known about the neural mechanisms that are responsible for coordinating the social behaviours (e.g. aggression) that occur in association with the formation and maintenance of these relationships. The purpose of the present study was to investigate the role of oxytocin (OXT) within the medial preoptic anterior hypothalamic continuum (MPOA‐AH) in the control of aggression in female hamsters. OXT injected into the MPOA‐AH immediately before testing significantly reduced the duration of aggression in a dose‐dependent manner. Injection of an OXT antagonist 30 min before testing significantly increased the duration of aggression. In contrast, the duration of aggression was not altered when hamsters were tested either 30 min after injection of OXT or immediately following injection of an OXT‐antagonist. These data support the hypothesis that OXT release within the MPOA‐AH regulates social behaviours important in the formation and maintenance of dominant subordinate relationships in female hamsters.
Central Administration of Neuropeptide FF Causes Activation of Oxytocin Paraventricular Hypothalamic Neurones That Project to the Brainstem
Authors: Jhamandas J. H. , MacTavish D.
Published: March 2003

Neuropeptide FF (NPFF), a morphine modulatory peptide, is emerging as an important neuromodulator in the context of central autonomic and neuroendocrine regulation. NPFF immunoreactivity and receptors have been identified in discrete autonomic regions within the brain and spinal cord, including the hypothalamic paraventricular nucleus (PVN). In this study, we examined the effects of intracerebroventricular (i.c.v.) administration of NPFF on activation of chemically identified PVN neurones that project to the brainstem nucleus of the solitary tract (NTS). In conscious rats, i.c.v. NPFF at a dose of 10 µg, but not 8 µg, caused an increase in arterial blood pressure. Immunohistochemical analysis revealed a dose‐dependent increase in activated (Fos positive) PVN neurones following i.c.v. NPFF administration compared to controls receiving i.c.v. saline. Activated PVN neurones were located predominantly in the parvocellular compartment of the nucleus with relatively few Fos positive cells in the magnocellular subdivision. Chemical identification of activated neurones revealed significant number of activated cells to be oxytocin positive, whereas only few vasopressin, tyrosine hydroxylase (TH) or corticotrophin‐releasing factor (CRF) neurones were double‐labelled. Injection of the retrograde tracer fluorogold into the NTS resulted in labelling of significant numbers of parvocellular oxytocin, but not vasopressin, TH or CRF, PVN neurones. We conclude that centrally administered NPFF stimulates brainstem‐projecting oxytocin PVN neurones. Oxytocin released from terminals within the NTS oxytocin thus modulate the activity of ascending visceral autonomic pathways that synapse initially within the NTS.
A clinical and radiographic study of 25 autotransplanted third molars
Authors: Akiyama  , Fukuda  , Hashimoto
Published: March 2003

SUMMARY This paper is a report on 25 autotransplantations of third molars with complete root formations. The study consists of 23 patients in whom 25 third molars were transplanted. The mean age was 29.6 years (range 20–54). In nine cases third molars were directly transplanted into the new socket. In 11 cases the sockets were widened and made deeper with a bur. In five cases the recipient beds were made by splitting osteotomy of the alveolar region. The transplanted third molars were stabilized with silk sutures, resin, wire splint or circumferential wiring for 1–6 weeks. Two–three weeks after transplantation, the root canals were treated and filled. After operation, the marginal and the periapical conditions were examined clinically and radiographically. The transplanted teeth clinically appeared to become firmer with the passage of time. Progressive root resorption was not found and good results were obtained. This study shows that autotransplantation of third molars with complete root formation produces an acceptable result using the procedures outlined.
Trigeminal responses evoked by painful electrical stimulation
Authors: Svensson  , Bakke  , Michler  , Arendt‐nielsen  , Møller
Published: March 2003

Trigeminal sensory and motor responses to high‐intensity electrical stimuli were studied in 10 healthy male subjects. During contraction at 10% of maximal bite force, late exteroceptive suppression periods assessed by EMG and bite force from masseter muscles were recorded together with evoked vertex potentials. Electrical stimuli were either delivered as 1 ms single pulses or as 21 ms (5 × 1 ms, 200 Hz) train pulses at two different intensities above the pain threshold. Three different perioral regions were stimulated in random order. The duration of the masseter suppression period was significantly longer and its latency significantly shorter at higher stimulus intensities whereas the amplitude of the evoked vertex potentials remained unchanged. Both the evoked potentials and the exteroceptive suppression period in the masseter muscle differed significantly between stimulation at the three perioral regions. The present results from combined measurements of sensory and motor responses in the trigeminal system may be explained by the function of trigeminal polysynaptic reflex circuits and the central cerebral processing of afferent inputs.
Effects of different surface treatment methods on the bond strength of composite resin to porcelain
Authors: Shahverdi S. , Canay Sû. , Sûahin E. , Bilge A.
Published: March 2003

In this study failures of composite resin/porcelain interfaces under shear loading were examined. Porcelain firing were made onto metal cylinders and porcelain surfaces were roughened with burrs or treated with hydrofloric acid gel and/or sandblasted with a Microetcher®. Two silane coupling agents were used in five groups, each of which had 22 samples. All of the treated samples were restored with a hybrid‐type composite resin. Then each group was divided into two subgroups according to storage times of 24 h and 30 days. After thermocyling the samples which were stored for 30 days, all of the groups were subjected to shear force at the composite resin/porcelain interface until fracture occurred. The results showed that there were differences both in the 24‐h and 30‐day storage period bond strengths between the various surface treatment methods. The samples treated with all three of the Microetcher®, hydrofloric acid and silane exhibited the highest shear bond values after 24 h storage, followed by the microetched/silane and the hydrofluoric acid/silane groups (F: 570·31, P: 0·00). After 30 days, the highest mean shear bond strength values were again with samples treated by all three processes. The storage period and thermocycling decreased the bond strength of samples, however, there was a significant difference among groups (F: 1388·55, P: 0·00). Silane pre‐treatment of porcelain was important as the mean bond strength of sandblasted/etched specimens were significantly lower than the other groups which were treated mechanically, in 24 h. Sandblasting seems to have little effect on the bonding. The comparison of 24‐h and 30‐day samples have also significant difference (F: 91·4376, P: 0·00).
The polarized light microscopic appearance of caries‐like lesions adjacent to restored cavities in the crowns and roots of extracted human teeth
Authors: Gilmour A. S. M. , Edmunds D. H.
Published: March 2003

Longitudinal clinical studies indicate consistently that secondary caries is the major cause of failure of restorations. Recently there has been an increase in the number of fluoride‐containing materials coming to the market place and this has renewed the debate about the cariostatic effectiveness of such materials. The present study examined the histologic appearance of caries‐like lesions adjacent to a non‐fluoride‐containing material (amalgam), a low fluoride‐containing material (composite) and a moderate fluoride‐containing material (glass–ionomer). The artificial caries system used to produce lesions has been previously reported and is a microbial system using

Streptococcus mutans

NCTC 10832. The lesions produced were similar to naturally occurring lesions in many respects, indicating the usefulness of this

in vitro

technique. Variations in the appearance of lesions were found adjacent to the different materials and the effect of the fluoride contained within two of the materials is discussed.
Mastication, deglutition and speech considerations in prosthodontic rehabilitation of a total glossectomy patient
Authors: Çötert H. S. , Aras E.
Published: March 2003

Prosthetic rehabilitation of a total glossectomized patient and specifications of the appliance, which differs from those previously reported, are presented. The functional considerations and logic used to design such a device are described. Speech performance of the patient with and without the prosthesis, is compared with a perceptibility test. Improvement of the functions of mastication, swallowing and speech were found acceptable.
The limitations of the instantaneous centre of rotation in joint research
Authors: Chen J. , Katona T. R.
Published: March 2003

The limitations on the use of the instantaneous centre of rotation (ICR), as calculated from discrete displacement data, are often not fully appreciated. As a consequence, the concept of the ICR has been improperly applied in some instances. In this paper, the procedures used to compute the ICR are developed in detail, and the factors that affect the computed results are identified. With an example, it is shown that in addition to being path dependent, ICR location is also sampling increment size dependent. Therefore, it is not appropriate to consider the ICR as a rotation centre if the body is undergoing general planar (combined translation and rotation) motion because it does not uniquely characterize the movement.
Comparison of biting forces in different age and sex groups: a study of biting efficiency with mobile and non‐mobile teeth
Authors: Miyaura K. , Matsuka Y. , Morita M. , Yamashita A. , Watanabe T.
Published: March 2003

This study aimed (1) to investigate the influences of sex, age and number of teeth on biting ability through a descriptive survey, and (2) to compare the biting ability between the subjects with and without mobile teeth in a case‐control study. A total of 687 subjects cooperated in the descriptive survey. Each subject bit on a pressure detecting sheet with their maximum biting force. Three indices of biting ability: biting pressure (MPa), biting force (N) and occlusal contact area (mm2) were calculated from the impressed marks on the sheet using a high vision video processor system. These indices were correlated well with the number of teeth according to the multiple regression analysis. In the case‐control study, matching procedures with sex, age and number of teeth were performed between the subjects with and without mobile teeth. No differences in the three indices were observed between the two well‐balanced groups. The results showed that the number of teeth is most important to maintain biting ability, and that the presence of mobile teeth does not always reduce biting ability.
Age‐hardening associated with grain boundary precipitation in a commercial dental gold alloy
Authors: Kim H. I. , Jang M. I. , Kim M. S.
Published: March 2003

The aim of this study was to make clear the age‐hardening mechanism in a dental high carat gold alloy. For this purpose, age‐hardening behaviour of a commercial dental high carat gold alloy, 65·5wt% Au–14·0wt% Ag–10·0wt% Cu–8·9wt% Pt, was investigated by means of hardness testing, X‐ray diffraction study and scanning electron microscopy. Age‐hardening was generated by the coherency strain resulting from the transformation of the α single phase to the Ag‐rich α1 phase and the AuCu I type ordered phase. The coherency strain seemed to be associated with the nucleation of the AuCu ordered structure initially, and then was brought about with the simultaneous formation of the Ag‐rich α1 phase and the AuCu I type ordered phase. Hardening was attributed mainly to the very fine coherent precipitates of a lamellar structure composed of the Ag‐rich α1 phase and the AuCu I type ordered phase at grain boundaries, and softening, which occurred following prolonged ageing, was due to the coarsening of the fine lamellar structure by releasing the strain at the interfaces of the adjacent lamellae.
The effect of head posture on direction and stability of mandibular closing movement
Authors: Yamada R. , Ogawa T. , Koyano K.
Published: March 2003

This study investigated the effects of head posture on mandibular habitual closing movement. Ten healthy subjects were examined. Head posture was evaluated as a sagittally viewed inclination of the head, and was changed from 25° forward bending up to 30° backward bending in 5° increments. The mandibular opening and closing movement was measured at each head posture. As the head bended forward, the closing path approached the maximum intercuspal position from the anterior region, and as the head was bent backward, the closing path approached the maximum intercuspal position from the posterior region. However, the limit of this relationship was found when the head was bent forward to some extent. There was also a correlation between the head posture and the stability of the closing movement. The forward bending of the head decreased the stability of the closing path, and conversely, the backward bending increased the stability of the closing path. It was concluded that the head posture affects the direction and stability of the mandibular closing movement. Possible underlying reasons for these findings are masticatory muscle activity and the tension and resistance of inframandibular soft tissue varying with the change of head posture.
Adhesive primers for bonding cobalt–chromium alloy to resin
Authors: Yoshida K. , Kamada K. , Atsuta M.
Published: March 2003

This study evaluated the effect of five adhesive primers on the shear bond strength of a self‐curing resin to cobalt–chromium (Co‐Cr) alloy. The adhesive primers Acryl Bond® (AB, Shofu), Cesead Opaque Primer® (COP, Kuraray), Metacolor Opaque Bonding Liner® (MOBL, Sun‐Medical), Metal PrimerII® (MPII, GC) and MR. Bond® (MRB, Tokuyama) were used. A brass ring which was placed over the casting alloy disk surface non‐primed or primed with each primer was filled with the self‐curing MMA‐PMMA resin. The specimens were stored in water at 37 °C for 24 h and then immersed alternately in water baths at 4 °C and 60 °C for 1 min each for up to 50 000 thermal cycles before shear mode testing at a crosshead speed of 0·5 mm/min. All of the primers examined, except MOBL, improved the shear bond strength between the resin and Co‐Cr alloy compared with non‐primed specimens prior to thermal cycling. Regardless of which primer was used, the shear bond strength significantly differed between thermal cycles 0 and 50 000. However, after 50 000 thermal cycles, the bond strengths of resin to Co‐Cr alloy primed with COP or MPII were significantly greater than those of specimens primed with AB, MOBL or MRB and non‐primed controls. This study indicated that COP and MPII are effective primers to obtain higher bond strength between resin and Co‐Cr alloy.
Does chewing performance depend upon a specific masticatory pattern?
Authors: Yamashita S. , Hatch J. P. , Rugh J. D.
Published: March 2003

The purpose of this article is to review the literature concerning the ideal chewing pattern for best chewing performance. We conclude that at this time there is not one ideal chewing pattern which can be used clinically or in research to assess the health of the mastication apparatus nor to predict chewing performance. It is clear that human masticatory behaviour is one of the most complex human behaviours. Chewing is under the control of the central pattern generator located in the brain stem but is influenced by dental and temporomandibular joint morphology. The most important portion of the chewing cycle is the area entering and leaving the intercuspal position where gliding contacts occur. Maximal chewing capability will likely occur when the chewing pattern follows the dental anatomy unique to the individual. The chewing cycle appears to increase the lateral component of its movement when increased chewing efficiency is required. These situations include increased hardness or the size of bolus, the position of the bolus and the results of the proceeding chewing stroke. The chewing pattern for any one cycle is influenced by a number of factors, thus it is not surprising that the question of the ideal chewing pattern remains unresolved.
Evaluation of colour and hardness changes of soft lining materials in food colorant solutions
Authors: Canay Ş. , Hersek N. , Tulunoğlu I. , Uzun Gülay
Published: March 2003

The aim of this study was to measure the colour stability and viscoelastic properties of three commercially available soft lining materials in vitro, by exposing them to 3% erythrosine, tartrazine and sunset yellow solutions. The colour changes were determined using a computer controlled spectrophotometer. The colour change of three soft lining materials—Molloplast B, Flexor and Coe Super Soft—were determined after 1, 3 and 6 months storage in three different food colorant solutions. The colour changes of Molloplast B was not noticable. Only the initial colour value of Flexor was significantly different from the other time interval colour measurements. On the other hand, the colour difference of Coe Super Soft was found to be significantly different at all comparative time interval measurements (P<0·05). According to Shore A hardness values, Molloplast B had an initial hardness of 44 in all three solutions, and there was a slight increase after 6 months. Flexor had an initial hardness of 39, at the end of 6 months the hardness changed a little. Coe Super Soft was fairly hard after processing and Shore A hardness was initially 89 which increased to 95 later on. According to these results, only the hardness values of Coe Super Soft showed a statistically significant difference when compared using Wilcoxon signed rank test at the P<0·05 level. As a conclusion, silicon type soft lining material seems to be more resistant to colour change and hardness than the acrylic type soft liners.
The effect of interfacial failure around a class V composite restoration analysed by the finite element method
Authors: Rees J. S. , Jacobsen P. H.
Published: March 2003

Partial failure around the tooth–composite interface of a class V restoration is common due to the effects of polymerization shrinkage. The effect that this has on the force distribution of the remaining intact interfaces has not been investigated. The aim of this study was to quantify the effect that partial failure of an isolated cavity wall interface had on the force distribution around the remaining intact interfaces of a class V composite restoration in a lower first premolar using a two‐dimensional plane strain finite element model. Partial failure resulted in a 4–6‐fold increase in peak tensile and shear forces compared to a tooth with a fully intact cavity wall interface. In some instances, the peak stresses were greater than the known bond strengths of composite to dentine.
The diagnostic value of pressure algometry in myofascial pain of the jaw muscles
Authors: Farella M. , Michelotti A. , Steenks M. H. , Romeo R. , Cimino R. , Bosman F.
Published: March 2003

Recent evidence suggests that evaluation of muscle tenderness in temporomandibular disorders (TMDs) patients might be improved by the use of pressure algometry; nevertheless, the evaluation of the diagnostic value of this tool has received little attention. The aim of this study was to assess the diagnostic value of pressure algometry in myofascial pain of the jaw muscles, by calculation of sensitivity (Se), specificity (Sp) and positive predictive values (PPV). Pressure pain thresholds (PPTs) of masseter and anterior temporalis muscles were assessed in 40 female myogenous TMD patients and 40 age‐matched female controls. PPTs were significantly lower (P<0·001) in TMD patients than in control subjects for both masseter and temporalis muscles, being 40–50% of the control values. Setting a cutoff value 1 s.d. below the mean PPT values of control subject, sensitivity and specificity were 0·67 and 0·85, respectively, for the masseter muscle and 0·77 and 0·87, respectively, for the temporalis muscle. When taking into account the prevalences of myofascial pain in the general population and in TMD clinics, the PPV ranged from 0·5 to 0·7. As a result of the low PPV, pressure algometry has strong limitations when used as a solitary diagnostic tool.
Effect of three adhesive primers for a noble metal on the shear bond strengths of three resin cements
Authors: Yoshida K. , Kamada K. , Sawase T. , Atsuta M.
Published: March 2003

The purpose of this study was to evaluate the durability and shear bond strengths of the different combinations of three adhesive primers and three resin cements to a silver–palladium–copper–gold (Ag–Pd–Cu–Au) alloy. The adhesive primers Alloy Primer® (AP), Metal PrimerII® (MPII) and Metaltite® (MT), and the resin cements BistiteII® (BRII), Panavia Fluoro Cement® (PFC) and Super‐Bond C&B® (SB) were used. Two sizes of casting alloy disks were either non‐primed or primed and cemented with each of the three resin cements. The specimens were stored in a 37 °C water bath for 24 h and then immersed alternately in 4 and 60 °C water baths for 1 min each for up to 100 000 thermal cycles. Shear mode testing at a crosshead speed of 0·5 mm/min was then performed. The application of MPII or MT was effective for improving the shear bond strength between each of the three resin cements and the Ag–Pd–Cu–Au alloy compared with non‐primed specimens. However, when primed with MPII or MT and cemented with SB, the bond strength at 100 000 thermal cycles was significantly lower than that at thermal cycle 0. When primed with AP, the specimens cemented with BRII or PFC showed lower bond strength than non‐primed specimens and failed at the metal–resin cement interface at 100 000 thermal cycles. On the other hand, AP was effective in enhancing the shear bond strength of SB to the Ag–Pd–Cu–Au alloy. The five combined uses of an adhesive metal primer and resin cement (combinations of MPII or MT and BRII or PFC and AP and SB) are applicable to the cementation of prosthodontic restorations without complicated surface modification of the noble alloy.
Paradigmatic shifts in occlusion and temporomandibular disorders
Authors: Ash M. M.
Published: March 2003

There are several terms that identify proposed paradigms for the way things ought to be carried out in the health sciences: evidence‐based, cause‐and‐effect, diagnostic gold‐standard, patient‐centred‐outcomes, risk assessment, cost/benefit/risk, and efficacious/effective. Collectively these paradigms exhibit varying degrees of interdependence, and have the potential for changing the way dentistry is practiced. A paradigm can be thought of as a standard by which research and health science ought to be conducted and evaluated. In this sense scientists and clinicians try to figure out how to account for various observations and phenomena dictated by paradigms or models of health care; however, it may become necessary to shift to new paradigms that are more consistent with scientific and clinically reality. Some of the potential effects of these shifting paradigms on the practice and teaching of occlusion and temporomandibular disorders are considered.
Accelerated DNA fragmentation of the denture‐bearing mucosal epithelium in an animal model of diabetes
Authors: Maruo Y. , Sugimoto T. , Oka M. , Hara T. , Sato T.
Published: March 2003

This study examined the effect of masticatory pressure transmitted directly to the hard palate mucosa on the final stage of terminal differentiation of keratinizing system of rats with and without streptozotocin‐induced diabetes mellitus. In the nondiabetic rats with masticatory pressure, the number of terminal‐deoxynucleotidyl‐transferase‐mediated deoxyuridine‐triphospate‐biotin nick end labelling (TUNEL) positive cells tended to increase about twice as much as in the nondiabetic rats without pressure with and without denture. A similar tendency of increase was observed in the diabetic rats without pressure. The synergy of the mechanical pressure and diabetic condition for 2 weeks greatly accelerated the DNA fragmentation, showing 8‐fold increase in TUNEL positive cells over the normal control, and caused exfoliation of the stratum corneum. A 4‐week exposure of diabetics to the masticatory pressure induced laminar splitting in the midst of the spinosum. Some cells in the stratum granulosum exhibited a sign of DNA fragmentation when laminar splitting took place in the vital cell layer. Premature DNA fragmentation may disturb the adhesion between spinosum cells and prevent the maturation of stratum corneum. Increase in Bax protein‐like immunoreactivity in these epithelial cells as revealed by immunocytochemistry may underlie the premature DNA fragmentation in the oral masticatory epithelium under pressure in diabetic patients.
Changes in masticatory muscle activity according to food size in experimental human mastication
Authors: Miyawaki S. , Ohkochi N. , Kawakami T. , Sugimura M.
Published: March 2003

The purpose of this study was to investigate the changes in masticatory muscle activity according to food size in human mastication. Sixteen subjects performed deliberate unilateral chewing of similarly cone shaped hard gummy jellies weighing 5 and 10 g. The masseter and anterior temporal muscle activity on both sides was recorded for the first 10 strokes. The normalized muscle activity during the chewing of the 10 g jelly was significantly higher than that of the 5‐g jelly, and there was a considerably high significant correlationship between the muscle activity during the chewing of the 10‐ and 5‐g jellies in each muscle on each side. The 10 g/5 g jelly ratio for the masseter muscle activity on the non‐chewing side almost coincided with the theoretical energy ratio required to shear, although that of the chewing side was lower than the ratio. The 10 g/5 g jelly ratio for the temporal muscle activity on both sides almost coincided with the food height ratio. The results suggest that anterior temporal and masseter muscle activity changes according to the rate of change in the height of hard coherent food bolus and food resistance required to shear, respectively, during mastication.
Comparison of maximum bite force and dentate status between healthy and frail elderly persons
Authors: Miura H. , Watanabe S. , Isogai E. , Miura K.
Published: March 2003

The purpose of the present study was to (1) determine the standard value of maximum bite force and to (2) compare the maximum bite force of the elderly between healthy and frail subjects. Subjects included 349 healthy elderly individuals (149 males, 200 females) and 24 frail elderly individuals (seven males, 17 females) ranging from 65 to 74 years of age. Maximum bite force was evaluated using a Dental Prescale system™. The maximum bite force of the healthy subjects was significantly higher than that of the frail subjects in both males (P=0·020) and females (P=0·015). However, no significant difference was observed in the number of present teeth between the healthy and frail subjects. Median of maximum bite force in healthy males was 408˙0 N, and that of the healthy females was 243˙5 N. These results suggest that the frail elderly have latent bite force problems.
In vivo mandibular elastic deformation during clenching on pivots
Authors: Jiang Ting , Ai Minoru
Published: March 2003

Lower rigidly connected long span bridges supported by natural abutments or implants sometimes become loose, come off, or fracture after a period of usage. Many reasons have been discussed for these failures. However, few researchers have shown the influence of mandibular elastic deformation on the abutments, although this influence is likely to produce a distortion force between the abutment and prosthesis. Therefore, this study measured the elastic deformation of the human mandibular arch during clenching on pivots by using charge‐coupled device (CCD) cameras and an image analysing system. When the subjects clenched on the canines (unilaterally or bilaterally) or bilateral second molars, no mandibular deformation was found; whereas when the subjects clenched on the unilateral second molars, the mandibular arch on the non‐pivot side moved upward and inward and the straight line distances between the right and left measurement points decreased by 0·2 mm. The magnitude of deformation is smaller than the depressible limit of periodontal membrane. This suggests that the influence of mandibular deformation on the connected prosthesis is negligible in the case of the natural root supported long span bridge but should probably be considered in the case of the implant supported bridge.