bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Orchidectomy on Levels of the mRNAs Encoding Gonadotropin‐Releasing Hormone and Other Hypothalamic Peptides in the Adult Male Rhesus Monkey (Macaca mulatta)1
Authors: El Majdoubi M. , Ramaswamy S. , Sahu A. , Plant T. M.
Published: March 2003

The testicular regulation of luteinizing hormone (LH) secretion in the adult rhesus monkey is mediated by an indirect action of testosterone to decelerate pulsatile gonadotrophin releasing hormone (GnRH) release. Whether this negative feedback action of testosterone involves regulation of GnRH gene expression is unknown. Therefore, the effect of bilateral orchidectomy on hypothalamic levels of the mRNA encoding this hypophysiotropic factor was examined. The feedback action of testosterone is generally considered to be mediated through non‐GnRH cells, and the present experiment provided the opportunity to also examine testicular influences on mRNAs encoding putative hypothalamic factors implicated in the testicular regulation of LH secretion. Adult male rhesus monkeys were orchidectomized (n=5) or sham‐orchidectomized (n=5) and killed 6 weeks later, after a castration‐induced hypersecretion of LH was established. Separate preoptic and mediobasal hypothalamus containing areas were collected, and levels of GnRH mRNA, as well as those of mRNAs encoding pro‐opiomelanocortin (POMC), the γ‐aminobutyric acid (GABA) synthesizing enzymes (glutamic acid decarboxylase 65 and 67; GAD65 and GAD67, respectively), neuropeptide Y, galanin and transforming growth factor (TGF)α, were quantified using RNase protection assay. Values were expressed in terms of optical density relative to that of cyclophilin mRNA levels. Bilateral orchidectomy produced a significant increase in GnRH mRNA levels that was restricted to the mediobasal hypothalamus and that was associated with a significant decrease in POMC, GAD65 and GAD67 mRNA levels in this region of the hypothalamus. In contrast, neuropeptide Y, galanin and TGFα mRNA levels were not affected by castration. These results indicate that, in the monkey, the deceleration of pulsatile GnRH release that is imposed by the testis, and presumably mediated by testosterone, is associated with a concomitant down regulation of GnRH gene expression in the mediobasal hypothalamus. They also support the notion that this hypothalamic feedback action may be mediated by POMC‐and GABA‐producing neurones in the mediobasal hypothalamus.
The Active Phase‐Related Increase in Corticosterone and Aggression are Linked
Authors: Haller  , Millar  , Van De Schraaf  , De Kloet  , Kruk
Published: March 2003

Recently we demonstrated that corticosterone exerts an acute facilitatory effect on aggression in male rats. Corticosterone production reaches a maximum at the onset of the dark period, while male rats are more aggressive in the dark. Here we present evidence demonstrating that the corticosterone increase at the beginning of the dark period is causally linked to the increase in aggressiveness. We measured plasma corticosterone and quantified aggressive behaviour of male territorial rats at various time points of the day–night transition. Low aggression levels were observed in the full light period when plasma concentrations of corticosterone were low. An increase in plasma corticosterone occurred just prior to the dark phase, when aggressive responding was the highest. Aggressive behaviour remained high in the early dark period when corticosterone was still high. We found that blocking the high affinity mineralocorticoid receptor (MR) with spironolactone (5 or 10 mg/kg) during the early dark period dramatically and specifically reduced territorial aggression.
Attenuation of Hypothalamic‐Pituitary‐Adrenal Axis Stress Responses in Late Pregnancy: Changes in Feedforward and Feedback Mechanisms
Authors: Johnstone H. A. , Wigger A. , Douglas A. J. , Neumann I. D. , Landgraf R. , Seckl J. R. , Russell J. A.
Published: March 2003

The hypothalamic‐pituitary‐adrenal axis is hyporesponsive to stress in late pregnancy, exemplified as reduced adrenocorticotropic hormone (ACTH) and corticosterone responses to restraint, but the mechanisms are unknown. We investigated forward drive and negative feedback upon the hypothalamic‐pituitary‐adrenal axis in pregnant rats. Corticotropin‐releasing hormone (CRH) and vasopressin mRNA expression in the parvocellular paraventricular nucleus and mineralocorticoid and glucocorticoid receptor expression in the paraventricular nucleus and hippocampus were quantified with in situ hybridization. Because it can enhance the corticosterone negative feedback signal, 11β‐hydroxysteroid dehydrogenase type 1 (11β‐HSD1) bioactivity in these brain regions and anterior pituitary was measured in vitro, and ACTH and corticosterone stress responses were measured after intracerebroventricular glycyrrhetinic acid, an 11β‐HSD inhibitor. Changes in corticosterone feedback on ACTH secretion were examined after pharmacological adrenalectomy by metyrapone and aminoglutethimide. Parvocellular paraventricular nucleus CRH mRNA content was reduced on day 21 and the CRH mRNA : vasopressin mRNA ratio was unaltered, indicating decreased production of both CRH and vasopressin. An increase in glucocorticoid receptor mRNA expression in the dentate gyrus (mineralocorticoid receptor mRNA expression was unaltered) and increased 11β‐HSD1 activity in the paraventricular nucleus and anterior pituitary suggest an increase in slow negative feedback mechanisms in pregnancy, but glycyrrhetinic acid did not modify the stress response. After metyrapone/aminoglutethimide treatment, corticosterone decreased ACTH secretion more slowly in pregnancy, indicating a decrease in rapid feedback sensitivity. Thus, reduced forward drive rather than increased effectiveness of glucocorticoid negative feedback may underlie stress hyporesponsiveness of the hypothalamic‐pituitary‐adrenal axis in pregnancy.
Expression of Corticotropin Releasing Factor (CRF), Urocortin and CRF Type 1 Receptors in Hypothalamic‐Hypophyseal Systems Under Osmotic Stimulation
Authors: Imaki T. , Katsumata H. , Miyata M. , Naruse M. , Imaki J. , Minami S.
Published: March 2003

The expression of corticotropin releasing factor (CRF) and urocortin in hypothalamic magnocellular neurones increases in response to osmotic challenge. To gain a better understanding of the physiological roles of CRF and urocortin in fluid homeostasis, CRF, urocortin and CRF type 1 receptor (CRFR‐1) gene expression was examined in the hypothalamic‐hypophyseal system usingin situ and double‐label in situ hybridization following chronic salt loading. CRFR‐1 expression was further examined by immunohistochemistry and receptor binding. Ingestion of hypertonic saline by Sprague‐Dawley rats for 7 days induced CRF mRNA exclusively in the oxytocin neurones of the magnocellular paraventricular nucleus (PVN) and the supraoptic nucleus (SON), but induced CRFR‐1 mRNA in both oxytocin and vasopressin‐containing magnocellular neurones. Hypertonic saline treatment also increased urocortin mRNA expression in the PVN and the SON. In the SON, urocortin was localized to vasopressin and oxytocin neurones but was rarely seen in CRF‐positive cells. Changes in CRFR‐1 mRNA expression in magnocellular neurones by hypertonic saline treatment were accompanied by changes in CRFR‐1 protein levels and receptor binding. Hypertonic saline treatment increased CRFR‐1‐like immunoreactivity in the magnocellular PVN and SON, and decreased it in the parvocellular PVN. CRF receptor binding in the PVN and SON was also increased in response to osmotic stimulation. Finally, hypertonic saline treatment increased CRFR‐1 mRNA, CRFR‐1‐like immunoreactivity and CRF receptor binding in the intermediate pituitary. These results demonstrate that the increase in the expression of CRF and urocortin message in magnocellular neurones induced by salt loading is accompanied by an increase in CRF receptor levels and binding in the hypothalamus and intermediate pituitary. Thus, CRF and urocortin may exert modulatory effects locally within magnocellular neurones as well as at the pituitary gland in response to osmotic stimulation.
Purinergic Regulation of Intracellular Ca2+ Concentration of Rat Pituitary Folliculo‐Stellate Cells in Primary Culture
Authors: Uchiyama M. , Nakajima Y. , Sakuma Y. , Kato M.
Published: March 2003

Pituitary folliculo‐stellate cells (FSCs) are glia‐like cells in the anterior pituitary and are believed to modulate the activity of the pituitary endocrine cells. However, little is known what regulates the activity of FSCs. We hypothesized that ATP could act on FSCs, because ATP is coreleased with pituitary hormones from endocrine cells. To test this possibility, we examined the effect of ATP by measuring intracellular Ca2+ concentration [Ca2+]i of FSCs in primary culture. Both ATP and UTP increased the [Ca2+]i in a concentration‐dependent manner in a range between 0.1 µM and 10 µM. The response was completely suppressed by thapsigargin, an inhibitior of endoplasmic reticulum Ca2+‐ATPase, and was significantly suppressed by U‐73122, an inhibitor of phospholipase C. The response was also suppressed by caffeine, a blocker of IP3 receptor, whereas that was not suppressed by ryanodine, an antagonist of ryanodine receptor. These results indicate that ATP increases [Ca2+]i of FSCs by activating phospholipase C via P2Y purinergic receptor and suggest that ATP would be one of paracrine factors to FSCs in the anterior pituitary.
Serine/Threonine Phosphatase Inhibitors Decrease Adrenergic Arylalkylamine N‐Acetyltransferase Induction in the Rat Pineal Gland
Authors: Spessert R. , Rapp M. , Vollrath L.
Published: March 2003

Adrenergic regulation of the pineal enzyme serotonin N‐acetyltransferase [arylalkylamine N‐acetyltransferase (AA‐NAT); EC 2.3.1.87] accounts for the circadian rhythm in melatonin formation. In the present study, the role of protein phosphatases in the adrenergic regulation of rat pineal AA‐NAT was investigated using specific inhibitors. In cultured pineals, the serine/threonine phosphatase type 1 and type 2A inhibitors okadaic acid and calyculin A significantly decreased adrenergically or cAMP‐induced AA‐NAT activity, whereas the serine/threonine phosphatase type 2B inhibitor cypermethrin and tyrosine phosphatase inhibitor dephostatin were ineffective. Reverse transcriptase‐polymerase chain reaction (RT‐PCR) data indicate that okadaic acid exerts its effect on cAMP‐dependent AA‐NAT induction by downregulating the amount of AA‐NAT transcript. The ‘third’ messengers, inducible cAMP early repressor (ICER) and Fos‐related antigene‐2 (Fra‐2), are believed to play a negative role in pineal AA‐NAT transcription. Okadaic acid increased the cAMP responsiveness of neither ICER mRNA nor Fra‐2 mRNA. Therefore, the regulatory role of pineal serine/threonine phosphatases in adrenergically stimulated AA‐NAT expression probably does not depend on ICER or Fra‐2.
GABA Mediates Steroid‐Induced Astrocyte Differentiation in the Neonatal Rat Hypothalamus
Authors: Mong J. A. , Nuñez J. L. , McCarthy M. M.
Published: March 2003

Our previous work has demonstrated that astrocytes in the developing arcuate nucleus of the rat hypothalamus are sexually dimorphic as a result of differential exposure to oestradiol. Moreover, our experiments in neonatal rats suggest an absence of oestrogen receptors (ER) in arcuate nucleus astrocytes in vivo. This, along with the conspicuous lack of evidence in the literature confirming the presence of ER in arcuate nucleus astrocytes of the neonatal rat brain, led us to question the mechanism by which oestrogen induces changes in arcuate nucleus astrocyte morphology. Based on our previous findings that oestradiol increases γ‐aminobutyric acid (GABA) levels in the neonatal rat arcuate, we hypothesize that GABA is released from neighbouring oestrogen‐sensitive neurones and alters arcuate nucleus astrocyte morphology. Here, we report that in vivo reduction of GABA synthesis in the neonatal rat brain by antisense oligodeoxynucleotides to glutamic acid decarboxylase prevented gonadal steroid‐induced astrocyte differentiation in males and testosterone‐treated females. Conversely, activation of GABAA receptors with the agonist muscimol increased astrocyte differentiation in females in the absence of gonadal steroids. Given that GABA is made only in neurones and that its synthesis is increased by oestradiol, we conclude that it acts as a diffusible factor inducing the differentiation of neighbouring astrocytes.
Photoperiodic Control of Oestrous Cycles in Syrian Hamsters: Mediation by the Mediobasal Hypothalamus
Authors: Lewis D. , Freeman D. A. , Dark J. , Wynne‐Edwards K. E. , Zucker I.
Published: March 2003

To assess whether the mediobasal hypothalamus (MBH) is necessary for photoperiodic control of oestrous cycles and prolactin secretion, we tested intact female Syrian hamsters (controls) and those that had sustained unilateral or bilateral lesions of the MBH. All hamsters displayed 4‐day oestrous cycles postoperatively in the long‐day photoperiod (14 h light/day); control females and those with unilateral MBH damage ceased to undergo oestrous cycles approximately 8 weeks after transfer to a short‐day photocycle (10 h light/day), whereas 12 of 15 females with bilateral MBH lesions continued to generate 4‐day oestrous cycles throughout 22 weeks in short days. Serum prolactin concentrations were either undetectable or low in all hamsters 8 or 14 weeks after the transfer to short‐day lengths, but increased above long‐day baseline values by week 22. We conclude that melatonin‐binding sites in the MBH mediate suppression of oestrous cycles but not prolactin secretion by short‐day lengths; recovery of prolactin secretion in females during prolonged exposure to short‐day lengths reflects development of refractoriness to melatonin in a substrate distinct from the MBH. These findings suggest that separate neural pathways mediate photoperiodic control of gonadotropin and prolactin secretion in female hamsters.
Habituation and Cross‐Sensitization of Stress‐Induced Hypothalamic‐Pituitary‐Adrenal Activity: Effect of Lesions in the Paraventricular Nucleus of the Thalamus or Bed Nuclei of the Stria Terminalis
Authors: Fernandes G. A. , Perks P. , Cox N. K. M. , Lightman S. L. , Ingram C. D. , Shanks N.
Published: March 2003

Habituation of the hypothalamic‐pituitary‐adrenal (HPA) response to chronic intermittent restraint stress (30 min/day for 15 days) and the cross‐sensitization to a heterotypic stress [i.p. lipopolysaccharide (LPS)] were investigated in intact male Sprague Dawley rats, and in rats bearing quinolinic acid lesions to the medial anterior bed nuclei of the stria terminalis (BST) or anterior region of the paraventricular nucleus of the thalamus (PVT). In intact animals, a single period of restraint increased plasma corticosterone levels at 30 min and led to an increase in corticotropin‐releasing hormone (CRH) mRNA levels in the PVN at 3 h. LPS had a smaller effect on corticosterone and more variable effect on CRH mRNA. Chronic intermittent restraint stress caused a decrease in body weight and increase in adrenal weights, with concomitant increase in basal corticosterone levels. These animals also displayed marked habituation of the corticosterone and CRH mRNA responses to the homotypic stress of restraint, but no loss of the corticosterone response to the heterotypic stress of LPS and a cross‐sensitization of the CRH mRNA response. This pattern of stress responses in control and chronically stressed animals was not significantly affected by lesions to the PVT or BST, two areas which have been implicated in the coping response to stress. Thus, these data provide evidence for independent adaptive mechanisms regulating HPA responses to psychological and immune stressors, but suggest that neither the medial anterior BST nor the anterior PVT participate in the mechanisms of habituation or cross‐sensitization.
Cocaine and Amphetamine‐Regulated Transcript mRNA Regulation in the Hypothalamus in Lean and Obese Rodents
Authors: Robson A. J. , Rousseau K. , Loudon A. S. I. , Ebling F. J. P.
Published: March 2003

Cocaine and amphetamine‐regulated transcript (CART) mRNA and immunoreactivity are expressed abundantly in the hypothalamus. Central administration of various fragments of this neuropeptide decreases food intake in rodents. To find out whether CART might play a role in the physiological regulation of energy balance, we used in situ hybridization to investigate whether CART mRNA abundance changed in two chronic obese/fat versus lean states and after acute dietary restriction. In the first study, mice were treated with goldthioglucose to destroy glucose‐responsive neurones in the ventromedial hypothalamus. This produced hyperphagia and obesity: 7 weeks after treatment, those receiving goldthioglucose weighed 70% more than the controls. CART mRNA abundance in the arcuate nucleus of goldthioglucose‐treated mice was decreased by 71% compared to levels in the control mice, but CART expression was unaffected in the dorsolateral hypothalamus. In the second study, male Siberian hamsters were exposed to short days to induce a physiological winter response in which body weight decreases as fat reserves are catabolized, and food intake correspondingly declines. After 8 weeks in short days, body weight had declined by 18% relative to controls maintained in long days in a summer fat state. CART mRNA levels did not differ significantly between the two groups in any hypothalamic areas. In the third study, male Siberian hamsters, either in long days or after 12 weeks exposure to short days to induce weight loss, were subject to a 48‐h period of fasting. Although photoperiod per se did not affect CART expression, fasting produced a significant decrease in CART mRNA in the arcuate nucleus of hamsters in both the long‐ and short‐day state. We conclude that CART‐producing cells are involved in energy homeostasis: the marked decrease in CART expression in the arcuate nucleus in goldthioglucose‐lesioned mice may contribute to the development of obesity, and the decrease following acute dietary restriction in hamsters may reflect a compensatory mechanism to reduce caloric expenditure, but our results do not indicate that CART is involved in long‐term seasonal regulation of body weight.
Gender Specific Effect of Neonatal Handling on Stress Reactivity of Adolescent Rats
Authors: Park M. K. , Hoang T. A. , Belluzzi J. D. , Leslie F. M.
Published: March 2003

Early neonatal handling of rat pups produces dampened hypothalamic‐pituitary‐adrenal axis reactivity to stress in adult male offspring. However, less is known about whether there is a similar effect for females. Although, most studies of neonatal handling have examined subsequent effects during adulthood, adolescence is an important developmental stage for stress responsivity. To address these issues, the effect of neonatal handling on the endocrine stress response and brain activity of male and female rats was determined in response to acute restraint stress during adolescence. Consistent with previous findings in adult males, neonatal handling reduced restraint stress‐induced hormone levels in adolescent males. However, in contrast, we found elevated plasma hormone concentrations in handled females. A gender‐specific handling effect on brain activity was also evident, with significantly increased stress‐induced activation of the posterior cingulate cortex of handled females, as measured by c‐fos mRNA expression. The striking gender difference in the effect of early neonatal handling provides evidence that this must be considered as an important variable in subsequent stress responsivity induced by early manipulations.
Attempted evaluation of three porcelain repair systems ‐ what are we really testing?
Authors: Chadwick  , Mason  , Sharp
Published: March 2003

summary Porcelain restorations are widely used in restorative dentistry with general success. On occasion however, fracture of the porcelain occurs. Sometimes a repair may be attempted using resin composite and one of the many bonding systems available. This in vitro investigation sought to determine and compare the shear bond strengths between a visible light‐cured resin composite (Prisma TPH) and dental porcelain (Matchmaker Porcelain) for three different bonding systems (Scotchbond Multipurpose Plus (SMP); One‐Step (OS); DenTASTIC (D)) with a view to conducting a larger study to assist in material selection. All measurements were performed one week following the preparation and storage of specimens in distilled water, at 37°C, using a Universal Testing Machine at a crosshead speed of 0·5 mm/min. Although the mean shear bond strengths differed significantly (P < 0·05) (OS > SMP) and the Weibull modulus value of SMP was significantly (P < 0·05) lower than both OS and D the almost exclusive cohesive mode of failure observed, within the porcelain itself, suggested that the test was more a reflection of the quality of the underlying porcelain than the union under investigation. It was thus concluded that the shear bond strength test employed here, and in other studies did not truly reflect the shear bond strength at the porcelain/composite interface and that a more meaningful test should be developed. The observed cohesive failure may account for repeated clinical failures of porcelain repairs where bonding to an inherently flawed porcelain structure inevitably results in further failure.
In vitro study of the effect of thermo‐ and load‐cycling on the bond strength of porcelain repair systems
Authors: Leibrock A. , Degenhart M. , Behr M. , Rosentritt M. , Handel G.
Published: March 2003

Fracture of porcelain fused to metal veneering may cause premature failure of fixed partial prosthodontics. Through the use of intra‐oral composite bonded porcelain repair systems, the replacement of the prosthetic reconstruction can be avoided. The aim of this study was to evaluate the shear bond strength of porcelain repair systems currently in use and the effect of thermocycling and mechanical loading (TCML) on the adhesion of composite to ceramic surfaces in comparison with the composite to metal bonding system Rocatec®. Specimens were fabricated by fusing the veneering ceramic VMK‐68® (Vita) to Co‐Cr‐Mo‐alloy base plates. Twenty cylindrically shaped composite samples in each series were bonded to the porcelain surface using porcelain repair systems currently in use. The shear bond strength of 10 samples was evaluated after 24 h (baseline) and after loading in an artificial oral environment. The repair systems Z 100 Kit®, Monobond S/Tetric® and Porcelain Etch® were not impaired by TCML and exhibited a shear bond strength of greater than 12 MPa, which was comparable to the control group Rocatec®. The shear strength of the repair systems Silistor® and All‐Bond® 2 decreased significantly after TCML. Using the appropriate repair system, the repair of ceramic‐veneered fixed partial prosthodontics can be recommended as a medium term alternative to a new reconstruction.
Tensile bond strengths of hard chairside reline resins as influenced by water storage
Authors: Cucci A. L. M. , Rached R. N. , Giampaolo E. T. , Vergani C. E.
Published: March 2003

Due to gradual resorption of the edentulous ridge bone, removable prostheses often require denture base relines to improve fit and stability. This research evaluated the bond strength between one heat‐cured acrylic resin (Lucitone 550®) and two hard chairside reline resins, after two different periods of storage in water (50 h and 30 days). The bond strength was evaluated using a tensile test. The mode of failure, adhesive or cohesive, was also recorded. The results submitted to the Kruskal–Wallis test indicated that the highest tensile strengths were achieved with intact Lucitone 550® denture base resin in both periods of storage in water. After 50 h of storage in water, Duraliner II® reline material exhibited the highest bond strength to the denture base resin. After 30 days of storage in water, Duraliner II® reline resin demonstrated a significant reduction in adhesion, showing lower tensile bond strength than Kooliner® material. Both hard chairside reline materials failed adhesively across Lucitone 550® denture base resin, in both periods of time.
Effect of disinfectant application methods on the bond strength of composite to dentin
Authors: Gürgan S. , Bolay Ş. , Kiremitçi; A.
Published: March 2003

The use of cavity disinfectants with composite resins has raised important questions regarding their potential adverse effects on bond strength. The purpose of this study was to evaluate the effect of cavity disinfection on the bond strength of composite resin to dentin. Buccal surfaces of 64 caries‐free extracted human third molars were ground flat by diamond flat‐end cylinder bur, polished with a series of silicon carbide abrasive papers and mounted in autopolymerizing acrylic resin. They were randomly distributed into four groups (of 16). In group 1 (control group), dentin surfaces were treated with 35% phosphoric acid, Permagen primer and Permagen bonding resin and no disinfectant was used. In group 2, cavity disinfectant was applied and acid etching, priming and bonding procedures were performed as in group 1. In group 3, cavity disinfectant was applied after acid etching. In group 4, cavity disinfectant was applied as in group 3, but it was rinsed off before priming and bonding procedures. Then a Teflon mould 3 mm thick and 4 mm in diameter was attached to the dentin surfaces, filled with composite resin and light polymerized. After the specimens had been thermocycled, shear bond strengths were determined. Application of the disinfectant before or after acid etching significantly reduced the shear bond strength of composite to dentin (P<0·05). Rinsing off the cavity disinfectant before the bonding procedure did not affect the bond strength (P>0·05). The use of cavity disinfectant with composite resin restorations can influence the dentin bond strength.
A natural tooth's stress distribution in occlusion with a dental implant
Authors: Akpinar I. , Anil N. , Parnas L.
Published: March 2003

The loss of one or more teeth is normally treated with conventional fixed or removable partial dentures or with implant supported fixed or removable dentures. This study investigated stresses formed around the implant and the antagonist natural tooth under occlusal force in the substitution of a missing lower first molar with a rigid or resilient IMZ (Intra Mobil Zylinder) implant, using the finite element stress analysis method. The results indicate that a bite force of 143 N resulted in high compressive stresses around the roots of a natural tooth opposing a restoration supported by an IMZ implant with rigid type abutment. It is speculated that these high compressive stresses may contribute to intrusion of the tooth.
Stress distribution in the temporomandibular joint affected by anterior disc displacement: a three‐dimensional analytic approach with the finite‐element method
Authors: E. Tanaka , D. P. Rodrigo , Y. Miyawaki , K. Lee , K. Yamaguchi , K. Tanne
Published: March 2003

The purpose of this study was to investigate the influences of anterior disc displacement on TMJ loading during maximum clenching by use of finite‐element analysis. Based on a young human dry skull, an analytic model of the mandible including the TMJ was developed. In addition to the standard model with normal disc–condyle relation, two models were designed to simulate various degrees of anterior disc displacement. In the standard model, compressive stresses were induced in the anterior, middle and lateral areas on the condyle and glenoid fossa, whereas tensile stresses were observed in the posterior and medial regions. In the models with anterior disc displacement, compressive stresses were recognized in all the areas of TMJ components excluding the bilaminar zone. Shear stresses in the articular disc and bilaminar zone significantly increased in most areas. In conclusion, stress distributions in the TMJ with a normal disc position was substantially different from those with anterior disc displacement, suggesting that the progress in disc displacement may have some association with the nature of stress distributions in the TMJ, in the articular disc in particular.
The relation of mandibular laterotrusion with ipsilateral TMJ clicking
Authors: Yang Y. , Yatabe M. , Ai M. , Soneda K.
Published: March 2003

The purpose of this study was to investigate the association of temporomandibular joint (TMJ) clicking with the types of canine guidance, the tracing patterns of mandibular laterotrusion and, especially, with the movements of the working side condyle. In a young subject group, the movements of left and right mandibular laterotrusion were measured at the incisal and the lateral pole point of the working side condyle. All samples were divided into one of two groups according to the mesial (M) or distal (D) canine guidance. They were also divided into protrusive laterotrusion (PL) or retrusive laterotrusion (RL) groups according to the tracing patterns. The incidence of clicking was 23·8% in all 84 TMJs. There was no significant difference between the M and the D groups. However, clicking occurrence was significantly higher in the RL than in the PL group (P<0·05). The condyles in clicking joints moved more posterior in ipsilateral laterotrusion than the condyles in non‐clicking joints. The condyles in RL also moved more posterior than those in PL. It is suggested that the posterior movement of the working side condyle in RL has a strong relationship with the internal derangement of the TMJ. However, it is not related to the type of canine guidance.
An investigation into the importance of the periodontal ligament and alveolar bone as supporting structures in finite element studies
Authors: Rees J. S.
Published: March 2003

Many finite element analyses studies have been published in the dental literature. Some of these have analysed just the crown of the tooth, others have included part or all of the root, while others have included the supporting periodontal ligament and alveolar bone. The aim of this study was to examine which of the supporting structures was important to the model when analysing the stress distribution within a tooth. A two‐dimensional plane strain finite element model of a lower second pre‐molar was developed, which included the supporting periodontal ligament and alveolar bone. Two 50 N loads were applied to simulate the effect of a load in centric occlusion. The nodal x, y and shear stresses were recorded along two horizontal planes, one in the crown and one in the cervical region. Each of the supporting structures was systematically removed and the remaining structures reanalysed. It was found that it was particularly important to include both the periodontal ligament and alveolar bone when undertaking the finite element analyses of teeth.
The distribution of cyclooxygenase‐1 in human temporomandibular joint samples: an immunohistochemical study
Authors: Yoshida H. , Fukumura Y. , Fujita S. , Nishida M. , Iizuka T.
Published: March 2003

Cyclooxygenase‐1,2 (COX‐1,2) or prostaglandin (PG) H synthase, is the first enzyme of the pathway in which arachidonic acid is oxidized to PGs. Thus, we examined the expression of COX‐1 in 16 human temporomandibular joint (TMJ) samples with internal derangement and in 10 control specimens by an immunohistological technique using paraffin‐embedded tissue and specific antihuman COX‐1 polyclonal antibody. There was obvious distinction of COX‐1 immunoreactivity between the control specimens and internal derangement cases, at the endothelial cells and fibroblasts, in the region of posterior and/or anterior loose connective tissues and synovial membrane. The findings of the present study suggest that COX‐1 might be an important mechanism for maintaining normal homeostasis at the endothelial cells and fibroblasts with internal derangement of TMJ.
Influence of thermal cycles in water on flexural strength of laboratory‐processed composite resin
Authors: Kawano Fumiaki , Ohguri Takafumi , Ichikawa Tetsuo , Matsumoto Naoyuki
Published: March 2003

Recently a new generation of laboratory‐processed composite resins containing submicron glass fillers was introduced, with claims of high strength. The purpose of this study was to evaluate the effect of thermal cycling in water on the flexural strength and hardness of several laboratory composite systems. The flexural strength of the new laboratory processed composite resins (Artglass [AG], Targis [TR] and Estenia [ES]) was significantly higher than that of conventional resins (Dentacolor [DC] and Cesead II [CS]). Thermocycling caused a reduction of the flexural strength but not a reduction of the hardness for most of materials tested. It was concluded that thermocycling affected the properties of the laboratory‐processed hybrid type composite resin, ES, AG and TR. However, the changes of these properties were smaller than those of microfine type composite resin DC. Thus, ES, AG and TR may maintain better properties during service compared with DC.
Dentists' perceptions of dentine hypersensitivity and knowledge of its treatment
Authors: Gillam D. G. , Bulman J. S. , Eijkman M. A. J. , Newman H. N.
Published: March 2003

The aim of the present investigation was to determine by questionnaire, UK dentists' perception of Dentine Hypersensitivity (DH) and knowledge of its treatment. A total of 403 questionnaires were sent to a selected group of UK dentists who had either inquired about further postgraduate education or had attended a course at the Eastman Dental Institute/Hospital. A total of 181 of 403 dentists (44·9%) (118M; 36F, 17 no response, mean age 38·2 years [s.d. 8·97]) returned the questionnaire. About 92·8% (n=168) of responding dentists claimed to see patients with DH in their practice. According to the dentists' replies at least one of four of their patients suffered from the complaint. About 71·8% (n=130) of dentists reported that DH was a severe problem in at least 10% of their patients and that pain from DH lasted no more than 4 weeks. Most of responding dentists claimed to be asked about DH by their patients and stated that they offered advice or treatment to their patients. Nearly 87·3% (n=158) of responding dentists provided a wide range of treatment options/advice which included both In‐office and over‐the‐counter (OTC) products. Popular responses included desensitizing pastes/gels, Topical F– varnishes and toothpastes/rinses/gels, advice on atraumatic tooth brushing, dentine bonding agents (DBA), glass–ionomer cements (GIC) and other unspecified restorations. Of the various In‐office treatments Duraphat was the most cited choice of varnish/primer options. Sensodyne toothpaste was the most popular of the specified OTC products. Most dentists appeared to understand the aetiological features associated with DH and provided a wide range of factors including the effects of incorrect tooth brushing, dietary acids as well as the possible influence on non‐dental topics such as stress. Most responding dentists believed that their advice on DH was generally effective although they did highlight that certain aspects on the condition were lacking such as appropriate scientific information including the prevention of DH and its treatment. The results from the present study highlight several discrepancies in the perception and knowledge of the treatment of DH between dentists and their patients. The results from this study are, however, reasonably consistent with those previously reported by Dutch investigators. The results from this study also highlighted a need for guidelines on the aetiology, prevention and treatment of DH for both dentists and their patients. The reported average frequency and duration of discomfort from DH by the responding dentists appeared to be consistent with the available literature.
Effect of wash bulk on the accuracy of polyvinyl siloxane putty‐wash impressions
Authors: Nissan J. , Gross M. , Shifman A. , Assif D.
Published: March 2003

Variations in the bulk of wash in a putty‐wash impression technique can result in dimensional changes proportional to the thickness of the wash material during setting. The purpose of the study was to determine the amount of wash necessary to achieve accurate stone models while using a two‐step putty‐wash impression technique with polyvinyl siloxane (PVS) impression material. A total of 45 impressions were made of a stainless steel master model, 15 impressions for each wash thickness (1, 2 and 3 mm). The model contained three full‐crown abutment preparations, which were used as the positive control. Accuracy was assessed by measuring six dimensions (occlusogingival and interabutments) on stone dies poured from impressions of the master model. One‐way analysis of variance (ANOVA) showed statistically significant differences amongst the three wash bulk groups, for all occlusogingival and interabutment measurements (P < 0·001). The overall discrepancies of the groups using wash thickness of 1 and 2 mm were smaller than the group with 3 mm wash thickness. Therefore, wash bulks of 1 and 2 mm were most accurate for fabricating stone dies, using PVS impression materials. This can be achieved by using the temporary crown to create the desired wash space in the preliminary putty impression. Wash thickness > 2 mm was inadequate to obtain accurate stone dies.
The effects of a novel Bioglass® dentifrice on dentine sensitivity: a scanning electron microscopy investigation
Authors: Gillam D. G. , Tang J. Y. , Mordan N. J. , Newman H. N.
Published: March 2003

Dentine sensitivity (DS) is a common condition which affects 8–35% of the population. Both In‐Office and Over‐the‐Counter products have been used in treatment, usually occluding open dentine tubules on the exposed root surface. Currently there appears to be no ideal material which permanently occludes dentine tubules. Bioactive and biocompatible glasses are known to induce osteogenesis in physiological systems and may offer suitable materials for surface reactivity which could theoretically occlude tubules. A new dentifrice formulation containing a modified Bioglass® material replacing part of the abrasive silica component was compared with original 45S6 bioactive glass. Dentine discs were treated with original Bioglass®, three coded dentifrices containing 0, 2·5 and 7·5% Bioglass® and two further selected dentifrice products. These specimens were prepared for scanning electron microscopy (SEM) and viewed in a Cambridge stereoscan 90B. The results demonstrated that original bioactive glass particles covered the dentine surface and/or occluded dentine tubules, although this original formulation was easily dislodged. Dentifrice with different ratios of added Bioglass® was assessed to provide greater surface coverage and tubule occlusion than without Bioglass®. It was concluded that the inclusion of bioactive glass particles in a suitably formulated vehicle may be an effective agent for the treatment of dentine sensitivity.
Acoustic characteristics of sounds from temporomandibular joints with and without effusion: an MRI study
Authors: Sano T. , Widmalm S.‐E. , Westesson P.‐L. , Yamaga T. , Yamamoto M. , Takahashi K. , Michi K.‐I. , Okano T.
Published: March 2003

Joint effusion has been associated with temporomandibular joint (TMJ) pain but can only be diagnosed by magnetic resonance imaging (MRI). For screening of patients with suspected effusion a simple and less expensive method would be desirable. We recorded joint sounds during jaw opening and closing movement from 34 TMJs with internal derangement (ID). Seventeen joints had joint effusion seen on MRI. Spectrograms of the sounds were displayed as waterfall plots showing profiles of the consecutive Hamming windows. If the profiles were similar, as judged by initial evaluation, the displayed pattern was classified as stable. If some profiles were distinctly deviating in their pattern, this was classified as unstable. Joints with effusion showed unstable sound pattern more often than joints without effusion (P < 0·001). It was concluded that TMJ sound analyses have a potential to identify joints with effusion based on their unstable sound pattern.
Differences in the fatigue of masticatory and neck muscles between male and female
Authors: Ueda H. M. , Kato M. , Saifuddin M. , Tabe H. , Yamaguchi K. , Tanne K.
Published: March 2003

The purpose of this study was to investigate the nature of fatigue and recovery of masticatory and neck muscles and the differences between sexes in normal subjects during experimentally induced loading. Subjects consisted of eight males (mean age: 27·6 years) and eight females (mean age: 24·2 years) selected from the volunteers in the Faculty of Dentistry, Hiroshima University. The inclusion criteria for the subjects were as follows: (1) good general health, (2) normal horizontal and vertical skeletal relationships, (3) no severe malocclusions and (4) no complaints of temporomandibular disorders. Each subject was requested to bite an occlusal‐force meter with 98, 196 and 294 N forces on the first molar region per side for 45 s. Activities of the masseter and sternocleidomastoid (SCM) muscles were recorded during these performances. Fatigue and recovery ratios were calculated with mean power frequency of power spectrum using a fast Fourier transform algorithm. Significant differences in the fatigue ratios between both sexes were found for the masseter muscle with 98, 196 and 294 N bite forces. Meanwhile, the SCM presented a significant difference between both sexes only at 98 N biting. Significant differences in the recovery ratios between both sexes were more prominent in the masseter muscle than in the SCM. These results suggest that the differences in muscle endurance between sexes may have some association with higher susceptibility of craniomandibular disorders in females than in males.
Bonding abutments to cast metal post/cores: comparison of pre‐treatment effects
Authors: Kajihara H. , Suzuki S. , Kurashige H. , Minesaki Y. , Tanaka T.
Published: March 2003

summary  Bond strengths were evaluated for (1) metal primer systems when the metal was contaminated by a dentin conditioner and (2) a dentin adhesive system when dentin was contaminated by metal primers. Disc specimens were cast in a silver–palladium–copper–gold (Ag–Pd–Cu–Au) alloy and dentin specimens were prepared by grinding the labial surface of bovine teeth. Specimens were treated with (1) metal primer alone, (2) dentin conditioner alone, (3) metal primer followed by dentin conditioner and (4) dentin conditioner followed by metal primer. A resin cement was poured into a mould over a restricted bonding area and allowed to set. Metal specimens were shear stressed to failure after thermocycling (4–60 °C; 20 000 cycles). Dentin specimens were stressed in the same manner after 24 h of immersion in 37 °C water. The results were compiled and analysed by anova. Data for dentin specimens treated with dentin conditioner only or with the combination of dentin conditioner and metal primer were not significantly different, statistically. Post‐thermocycled groups indicated that bond strengths to the alloy significantly decreased (P < 0·05) when the primed metal surface was contaminated with dentin conditioner regardless of the timing of its application.
Subtle coercion in psychiatric practice
Authors: Lützén
Published: March 2003

Making nursing decision for patients who cannot communicate their own wishes and needs is a common problem in psychiatric and mental health nursing. The aim of this article is to present the findings of a qualitative study focused on situations in which patients do not cooperate with a nursing decision about what should be done for them. The design of the study utilized some steps associated with the grounded theory method. Data were collected from unstructured interviews with 10 British nurses with long experience in psychiatric nursing. By implementing the strategy of constant comparative analysis of the transcribed interviews, it was found that nurses use different types of subtle coercion in order to achieve their own goals for the patient. These goals were justified as being in the best interest of the patient. The main components of subtle coercion are part of a process consisting of: assessing a patient's competency for self‐choice; acting strategically; modifying the principle of autonomy; justifying strategies; and reflecting ethically on the actions taken. The study indicates that further empirical investigation of clinical situations involving subtle coercion is required. Particular attention should be paid to organizational factors and how these contribute to the use of subtle coercion. A specific question that needs to be theoretically and empirically explored is, can coercion be justified as ‘ethically right’ in some situations but not in others?
A study of incidents of violence towards staff by patients in an NHS Trust hospital
Authors: Vanderslott
Published: March 2003

The aim of the study was to survey the degree and the extent of violence towards nursing staff by patients within a hospital environment. The information gathered will form a basis for future reference once the care packages are developed in the community. The study investigated the number of recorded incidents of aggression towards nursing staff by patients (n= 164) in an NHS Trust hospital for one year (October 1993–September 1994). The degree of recorded incidents of aggression was analysed using the Overt Aggression Scale. The results showed that the degree of aggression was mostly moderate to mild and occurred mostly in the Learning Disability Unit. Male staff were more involved in actual recorded incidents than expected in the given population. Health care assistants were more likely to be involved in aggressive incidents than any other grade of staff. There were significant findings in the time and location of the recorded aggressive incidents.

The study, therefore, highlights the need to report and record incidents, the need for ongoing training, skilful management of resources and the recognition of environmental factors that can lead to patients' violence and aggression towards nursing staff.
Objective measurement of mood change induced by contemporary music
Authors: Smith  , Noon
Published: March 2003

A myriad of previous studies from a variety of disciplines has shown several effects of music on mind and body. This study investigated the relationship between different categories of contemporary music (n = 6) and the mood states of a group of students (n = 12), using the Profile of Mood States (POMS), to measure mood before and after exposure to these different pieces of music. When analysed together, all six pieces of music produced an overall change in mood (P = 0.008) as measured by 2‐way repeated measures analysis of variance ( anova). When each category was examined individually, four categories of music produced highly significant changes in mood: the tense category (score – 4.0 ± 1.8 POMS Units; P < 0.001); depressed category ( + 0.5 ± 0.2; P < 0.001); angry category (+ 0.9 ± 1.6; P < 0.03); and the all moods category (1.6 ± 0.3; P < 0.04). One piece of dance music produced changes in all mood categories, giving the largest positive mean mood change. By contrast, the popular/independent music, associated with the tense category, produced the largest negative mean mood change. The five POMS mood states were analysed separately for each piece of music. These findings are consistent with previous work. In addition, the finding of the effects of specific music categories on mood may have important implications for therapy in mental health and mental health nursing.