bluuebunny/crossref_metadata_2025 huggingface dataset:
Cyclical Expression of Egr‐1/NGFI‐A in the Rat Anterior Pituitary: A Molecular Signal for Ovulation?
Authors: Slade  , Carter
Published: March 2003

Molecular genetic studies of egr‐1/NGFI‐A have recently established a key role for this immediate early gene in anterior pituitary development, and particularly in transcriptional regulation of the LH β‐subunit gene. These studies, using null mutant mice, addressed the developmental aspects of gonadotrophin gene regulation by egr‐1 and, because of the limitations of this approach, did not address the role of egr‐1 in adult reproductive physiology. Using the rat, we have now investigated the expression of egr‐1 during the female reproductive cycle, and have found evidence of cyclical changes in anterior pituitary egr‐1 expression, at mRNA, protein, and DNA binding activity levels. Specifically, we have shown that egr‐1 mRNA is significantly elevated during proestrous, and conversely suppressed on the subsequent day of oestrous. We have also demonstrated significantly raised levels of an approximately 70 kDa Egr‐1 immunoreactive protein band during the night of proestrous, together with markedly raised levels of a Egr‐1 consensus sequence DNA binding complex. These studies are indicative of both direct egr‐1 gene regulation by oestrogen, and also regulation by GnRH. Finally, we have sequenced previously uncharacterized regions of the egr‐1 gene and found evidence of a potential oestrogen response element. Our findings are consistent with the hypothesis that Egr‐1 forms at least part of the molecular signal for ovulation in the pituitary.
Effects of the Inhibition of Cyclo‐Oxygenase 1 or 2 or 5‐Lipoxygenase on the Activation of the Hypothalamic‐Pituitary‐Adrenal Axis Induced by Interleukin‐1β in the Male Rat
Authors: Parsadaniantz S. Mélik , Lebeau A. , Duval P. , Grimaldi B. , Terlain§ B. , Kerdelhué B.
Published: March 2003

The limited entry of interleukin‐1β (IL‐1β) into the central nervous system has led to the hypothesis that IL‐1β acts, through IL‐1β receptors located notably on endothelial cells, on the release of prostaglandins which in turn stimulate the hypothalamic‐pituitary‐adrenal (HPA) axis. We used cyclo‐oxygenase‐1 (COX‐1) and cyclo‐oxygenase‐2 (COX‐2) and 5‐lipoxygenase (5‐LOX) inhibitors, before the injection of IL‐1β, to explore the role of arachidonic acid metabolic pathways on HPA axis activation. Adult male rats were i.m injected 20 min before i.p injection of IL‐1β, with (i): a COX‐1/COX‐2 inhibitor (ketoprofen); (ii) a COX‐2 selective inhibitor (NS 398); or (iii) a 5‐LOX inhibitor (BW A4C). Following this, rats were killed 90 min after i.p. IL‐1β injection and analysis for plasma adrenocorticotropic hormone (ACTH) and corticosterone concentrations and determination of anterior pituitary pro‐opio melanocortin (POMC) gene transcription was conducted. Administration of the COX‐1/COX‐2 inhibitor led to a complete blockage of ACTH and corticosterone secretion and POMC gene transcription. The COX‐2 inhibitor led to a complete blockade of ACTH secretion and POMC gene transcription but had no effect on corticosterone secretion. The 5‐LOX inhibitor had no significant effect on any parameter. These results demonstrate the crucial role of eicosanoid pathways in mediating the stimulation of the HPA axis induced by IL‐1β. Moreover, we found a clear dissociation of the effect of the blockage of COXs upon ACTH and corticosterone secretion, suggesting that IL‐1β may act at the brain as well as at the adrenal cortex to stimulate the secretion of corticosterone.
Ontogeny of Aromatase and Tyrosine Hydroxylase Activity and of Aromatase‐Immunoreactive Cells in the Preoptic Area of Male and Female Japanese Quail
Authors: Balthazart J. , Tlemçani O. , Harada N. , Baillien M.
Published: March 2003

The aromatization of testosterone into oestrogens plays a key role in the control of many behavioural and physiological aspects of reproduction. In the quail preoptic area (POA), aromatase activity and the number of aromatase‐immunoreactive (ARO‐ir) cells are sexually differentiated (males > females). This sex difference is implicated in the control of the sexually dimorphic behavioural response of quail to testosterone. We analysed the ontogenetic development of this sex difference by measuring aromatase activity and counting ARO‐ir cells in the POA of males and females from day 1 post hatch to sexual maturity. We investigated in parallel another enzyme: tyrosine hydroxylase, the rate limiting step in catecholamine synthesis. Between hatching and 4 weeks of age, aromatase activity levels were low and equal in males and females. Aromatase activity then markedly increased in both sexes when subjects initiated their sexual maturation but this increase was more pronounced in males so that a marked difference in aromatase activity was present in 6 and 8 week‐old subjects. Tyrosine hydroxylase activity progressively increased with age starting immediately after hatching and there was no abrupt modification in the slope of this increase when birds became sexually mature. No sex difference was detected in the activity of this enzyme. The number of ARO‐ir cells in the POA progressively increased with age starting at hatching. No sex difference in ARO‐ir cell numbers could be detected before subjects reached full sexual maturity. The analysis of the three‐dimensional organization of ARO‐ir cells in the POA revealed that, with increasing ages, ARO‐ir cells acquire a progressively more lateral position: they are largely periventricular in young birds but they are found at higher density in the lateral part of the medial preoptic nucleus in adults. These data indicate that aromatase activity differentiates sexually when birds reach sexual maturity presumably under the activating effects of the increased testosterone levels in males. The number of ARO‐ir cells, however, begins to increase in a non sexually differentiated manner before the rise in plasma testosterone in parallel with the increased tyrosine hydroxylase activity. Whether this temporal coincidence results from a general ontogenetic pattern or from more direct causal links remains to be established.
Seasonal Changes in the Expression of Neuropeptide Y and Pro‐Opiomelanocortin mRNA in the Arcuate Nucleus of the Ovariectomized Ewe: Relationship to the Seasonal Appetite and Breeding Cycles
Authors: Clarke I. J. , Scott C. J. , Rao A. , Pompolo S. , Barker‐Gibb M. L.
Published: March 2003

Sheep experience well‐documented seasonal changes in reproductive activity and voluntary food intake (VFI). Within the hypothalamus, neurones that express neuropeptide Y (NPY) and pro‐opiomelanocortin (POMC) have been implicated in the regulation of reproduction and appetite. In this study, we aimed to determine the extent to which the expression of these two neuronal systems is linked to the seasonal reproductive cycle and/or the seasonal appetite cycle. VFI in our sheep reaches a nadir in August with no difference occurring between December and February. We examined the brains of ovariectomized (OVX) female sheep (n = 5–7) that were killed during the breeding season (February) or during the early or late nonbreeding season (August and December, respectively). The brains of these animals were perfused with paraformaldehyde and processed for in situ hybridization histochemistry, using ribonucleotide probes labelled with 35S. The number of NPY and POMC cells and the number of silver grains per cell were counted using an image analysis system. For NPY, the number of cells counted in the arcuate nucleus/median eminence region and the number of silver grains per cell was significantly lower in animals killed during August than in animals killed in February or December. The number of grains per cell over NPY cells was also significantly lower in animals killed during August. For POMC, the number of cells was lower in February than in August and December. Similarly, the number of grains per cell for POMC were lower in February than in August and December. VFI was significantly lower in animals during August than at other times of the year. We conclude that in OVX ewes: (i) NPY gene expression is lower at the time of the year when VFI is reduced and (ii) POMC gene expression is greater at the time of the nonbreeding season than during the breeding season. Because these results were obtained in OVX animals, the changes appear to be independent of alterations in the secretion and/or action of ovarian steroids. Thus, the activity of NPY neurones appears to relate to changes in appetite whereas changes in POMC expression may be relevant to the seasonal breeding cycle.
Androgens Alter Corticotropin Releasing Hormone and Arginine Vasopressin mRNA Within Forebrain Sites Known to Regulate Activity in the Hypothalamic‐Pituitary‐Adrenal Axis
Authors: Viau V. , Soriano L. , Dallman M. F.
Published: March 2003

To reveal direct effects of androgens, independent of glucocorticoids, we studied the effects of gonadectomy (GDX) in adrenalectomized (ADX) rats with or without androgen replacement on corticotropin releasing hormone (CRH) and arginine vasopressin (AVP) mRNA expression within various forebrain sites known to regulate the hypothalamic‐pituitary‐adrenal axis. These included the medial parvocellular portion of the paraventricular nucleus of the hypothalamus (mp PVN), the central and medial nuclei of the amygdala and bed nuclei of the stria terminalis (BNST). In the mp PVN, ADX stimulated both CRH and AVP mRNA expression. Combined ADX + GDX inhibited only AVP, and testosterone and dihydrotestosterone (DHT) restored AVP mRNA. In the central nucleus of the amygdala, ADX decreased CRH mRNA expression, and this response was unaffected by GDX ± testosterone or DHT replacement. In the medial amygdala, AVP mRNA expression was decreased by ADX, abolished by ADX + GDX, and restored by androgen replacement. ADX had no effect on CRH and AVP mRNA expression in the BNST. GDX + ADX, however, reduced CRH mRNA expression only within the fusiform nuclei of the BNST and reduced the number of AVP‐expressing neurones in the posterior BNST. Androgen replacement reversed both responses. In summary, in ADX rats, AVP, but not CRH mRNA expression in the amygdala and mp PVN, is sensitive to GDX ± androgen replacement. Both CRH‐ and AVP‐expressing neurones in the BNST respond to GDX and androgen replacement, but not to ADX alone. Because androgen receptors are not expressed by hypophysiotropic PVN neurones, we conclude that glucocorticoid‐independent, androgenic influences on medial parvocellular AVP mRNA expression are mediated upstream from the PVN, and may involve AVP‐related pathways in the medial amygdala, relayed to and through CRH‐ and AVP‐expressing neurones of the BNST.
The Role of Neuropeptide Y in Orexin‐Induced Hypothalamic‐Pituitary‐Adrenal Activation
Authors: Jászberényi M. , Bujdosó E. , Telegdy G.
Published: March 2003

The role of neuropeptide Y (NPY) in the mediation of orexin‐induced hypothalamic‐pituitary‐adrenal (HPA) activation was investigated in the rat. The HPA system was stimulated by intracerebroventricular (i.c.v.) administration of orexin‐A or orexin‐B (140 or 280 pmol, respectively) and the plasma concentration of corticosterone was used as an index of the degree of activation. i.c.v. pretreatment with NPY antagonist or NPY antiserum (30 min or 24 h before orexin administration, respectively) inhibited the orexin‐induced corticosterone release. The inhibitory actions of the antagonist and the antiserum were revealed by the dose–response curve; the highest concentrations practically abolished the HPA activation evoked by the orexins. These data suggest that the HPA system‐stimulating effect of the orexins may be mediated by NPY.
Hypothalamic Transforming Growth Factor β1 and Basic Fibroblast Growth Factor mRNA Expression is Modified During the Rat Oestrous Cycle
Authors: Galbiati M. , Magnaghi V. , Martini L. , Melcangi R. C.
Published: March 2003

The present observations show that the mRNA levels of two growth factors, previously described to be involved in the control of neurones synthesizing the luteinizing hormone releasing hormone (LHRH) [i.e. transforming growth factor β1 (TGFβ1) and basic fibroblast growth factor (bFGF)], fluctuate in the hypothalamus of adult female rats during the oestrous cycle. In particular, the expression of TGFβ1‐mRNA shows a peak on the morning of the day of proestrus, which precedes the increased secretion of the two gonadotrophins that occurs on that day. In the case of bFGF, the peak is evident in the evening of the same day and is concomitant with that of the gonadotrophins. We evaluated the effects of ovariectomy and of exogenous oestrogens on the mRNA levels of these two growth factors in the hypothalamus. The data indicate that 3 weeks of ovariectomy are not able to change the hypothalamic messenger levels of the two growth factors considered, which remain at the levels found in diestrus 1, and that 17β‐oestradiol is able to induce a significant increase of both TGFβ1‐ and of bFGF‐mRNA levels in the hypothalamus of the ovariectomized rat. The present in vivo observations support the concept, previously proposed on the basis of in vitro data, that growth factors, such as TGFβ1 and bFGF, play a role in the hypothalamic control of reproduction, and suggest that the control of LHRH dynamics involves a strict cooperation between gonadal steroids and growth factors.
High Voltage‐Activated Ca2+ Currents in Rat Supraoptic Neurones: Biophysical Properties and Expression of the Various Channel α1 Subunits
Authors: Joux N. , Chevaleyre V. , Alonso G. , Boissin‐Agasse L. , Moos F. C. , Desarménien M. G. , Hussy N.
Published: March 2003

The diversity of Ca2+ currents was studied in voltage‐clamped acutely dissociated neurones from the rat supraoptic nucleus (SON), and the expression of the various corresponding pore‐forming α1 subunits determined by immunohistochemistry. We observed the presence of all high voltage‐activated L‐, N‐, P/Q‐ and R‐type currents. We did not observe low‐voltage‐activated T‐type current. The multimodal current/voltage relationships of L‐ and R‐type currents indicated further heterogeneity within these current types, each exhibiting two components that differed by a high (−20 mV) and a lower (−40 mV) threshold potential of activation. L‐ and R‐type currents were fast activating and showed time‐dependent inactivation, conversely to N‐ and P/Q‐type currents, which activated more slowly and did not inactivate. The immunocytochemical staining indicated that the soma and proximal dendrites of SON neurones were immunoreactive for Cav1.2, Cav1.3 (forming L‐type channels), Cav2.1 (P/Q‐type), Cav2.2 (N‐type) and Cav2.3 subunits (R‐type). Each subunit exhibited further specificity in its distribution throughout the nucleus, and we particularly observed strong immunostaining of Cav1.3 and Cav2.3 subunits within the dendritic zone of the SON. These data show a high heterogeneity of Ca2+ channels in SON. neurones, both in their functional properties and cellular distribution. The lower threshold and rapidly activating L‐ and R‐type currents should underlie major Ca2+ entry during action potentials, while the slower and higher threshold N‐ and P/Q‐type currents should be preferentially recruited during burst activity. It will be of key interest to determine their respective role in the numerous Ca2+‐dependent events that control the activity and physiology of SON neurones
Regulation of Rat Adrenal Vasoactive Intestinal Peptide Content: Effects of Adrenocorticotropic Hormone Treatment and Changes in Dietary Sodium Intake
Authors: Hinson J. P. , Renshaw D. , Carroll M. , Kapas S.
Published: March 2003

Vasoactive intestinal peptide (VIP) is well established as a paracrine regulator of adrenal function. It is present in nerves supplying the adrenal cortex, although previous studies have found that the amount of VIP in the outer zones of the rat adrenal is not affected by ligating the splanchnic nerve supplying the adrenal gland. The present studies were designed to investigate the mechanisms involved in regulating the VIP content of the rat adrenal gland. This study examined the effects of changes in electrolyte balance and adrenocorticotropic hormone (ACTH) administration on the adrenal content of VIP as measured by radioimmunoassay. Rats on a low sodium diet had a significantly increased capsular/zona glomerulosa immunoreactive VIP (irVIP) level, while rats on a high sodium diet had suppressed levels relative to controls. Changes in dietary sodium did not affect inner zone/medullary VIP content. Administration of ACTH caused a decrease in irVIP levels in the capsular/zona glomerulosa portion of the adrenal gland but had no effect on the inner zone/medulla. Analysis of mRNA encoding VIP revealed a large increase in expression of VIP in the sodium‐deplete group compared with the control, with no change in VIP expression in the sodium‐loaded group. ACTH treatment was found to significantly decrease VIP mRNA levels in the capsular portion. Neither ACTH treatment nor changes in sodium intake affected inner zones/medullary VIP message. These data suggest that VIP in the capsule and zona glomerulosa region of the adrenal cortex is regulated in response to the physiological status of the animal, with changes in capsular/zona glomerulosa VIP correlating with changes in zona glomerulosa function.
Differential Expression of Vasoactive Intestinal Polypeptide Receptor 1 and 2 mRNA in Murine Intestinal T Lymphocyte Subtypes
Authors: Qian B.‐F. , Hammarström M.‐L. , Danielsson Å.
Published: March 2003

Neuropeptides may exert a variety of effects on the immune cells at both systemic and mucosal immune sites. The immunoregulatory properties refer to the ability of physiological signals and pathways to influence various immune functions. Vasoactive intestinal polypeptide (VIP), a neuropeptide present in high concentration in gut, was studied for its production and receptor expression in intraepithelial and lamina propria T lymphocytes of mouse intestine. Using reverse transcription‐polymerase chain reaction (RT‐PCR) analysis, it was demonstrated that VIP receptor 1 (VIPR1) was constantly expressed in intraepithelial and lamina propria T lymphocytes from both small and large intestine. In contrast, VIPR2 was identified only in T cells from small intestine. Further studies on purified subpopulations of T lymphocytes indicated the existence of VIPR2 in CD8+ T cells, but not CD4+ and CD4CD8 double negative T cells, although all these three subpopulations displayed VIPR1. In addition, VIPR1 mRNA was detected in splenic T lymphocytes, but no signal was obtained for VIPR2 mRNA, even after stimulation of the cells with anti‐CD3ε‐chain mAb, phorbol 12‐myristate 13‐acetate (PMA) and/or VIP. The presence of VIP receptor(s) on intestinal T lymphocytes was supported by the detection of VIP on the cell surface using dual colour immunoflowcytometry. In‐vitro treatment with VIP resulted in a tendency towards an increased size of the VIP immunoreactive T cell population and significantly enhanced the average immunofluorescence intensity of the surface labelling. This indicates that the receptors are partially occupied by locally produced VIP in vivo and that more peptide molecules can be bound on the lymphocytes when needed, released and accumulated in higher concentration at the action sites. We failed to detect the expression of VIP mRNA in T lymphocytes, from either intestine or spleen. These observations support that VIP may be an important immune modulator in gut acting through specific receptors on T lymphocytes. The differential mRNA expression of VIP receptor subtypes in cells with different phenotypes and in different immune compartments may suggest diverse regulatory roles of the neuropeptide in immune responses.
Modulation of Gonadotropin II Release by K+ Channel Blockers in Goldfish Gonadotropes: A Novel Stimulatory Action of 4‐Aminopyridine
Authors: Wong C. J. H. , Kwong P. , Johnson J. D. , Yunker W. K. , Chang J. P.
Published: March 2003

The effects of K+ channel blockers on basal gonadotropin II (GTH‐II) release were examined in cultured goldfish gonadotropes. Tetraethylammonium (TEA) inhibited basal GTH‐II release, whereas 4‐aminopyridine (4‐AP) increased basal release, although both K+ channel blockers generated increases in [Ca2+]i. Other K+ channel blockers had no significant effect on GTH‐II release. We examined whether Ca2+ entry that arises from blockade of K+ channels by 4‐AP mediates the secretory response. Secretion evoked by 4‐AP was slightly reduced by TEA but was unaffected by reducing Ca2+ entry using either an inhibitor of Ca2+ channels, verapamil, or nominally Ca2+‐free medium. In contrast, the Ca2+ signal evoked by 4‐AP was largely blocked by Ca2+‐free medium, as predicted by its inhibitory action on K+ channels. Together, these data suggest that the hormone release response to 4‐AP is independent of entry of extracellular Ca2+. Finally, the mechanism of hormone release evoked by 4‐AP appeared to be independent of mechanism(s) evoked by caffeine since 4‐AP did not affect caffeine‐evoked release and caffeine did not affect 4‐AP evoked release. That both 4‐AP and TEA generated Ca2+ signals but affected hormone release in either an extracellular Ca2+ independent (4‐AP) or inhibitory (TEA) manner suggests that Ca2+ entry is linked to GTH‐II secretion in a highly nonlinear fashion.
Response to Male Odours in Progestin Receptor‐ and Oestrogen Receptor‐Containing Cells in Female Rat Brain
Authors: Bennett A. L. , Gréco B. , Blasberg M. E. , Blaustein J. D.
Published: March 2003

Sensory cues from male rats, such as odours and vaginal‐cervical stimulation (VCS), play a modulatory role in female rat sexual behaviour. For example, exposure to male odours and VCS appears to be at least partially responsible for increases in sexual behaviour following repeated mating of oestradiol‐primed female rats. Although there is evidence that VCS influences sexual behaviour via a ligand‐independent progestin receptor (PR)‐dependent mechanism, the mechanism by which odours influence sexual behaviour is not known. We tested the hypothesis that, similar to VCS, the effects of male odours on sexual behaviour are mediated by progestin receptors. Female rats were injected with the progestin antagonist, RU486, or oil vehicle and were then exposed to male‐soiled bedding or clean bedding. Although exposure to male‐soiled bedding resulted in higher levels of Fos immunoreactivity in brain areas associated with female sexual behaviour, the progestin antagonist did not reduce this effect. Furthermore, there was minimal coexpression of odour‐induced Fos and progestin receptors in brain areas associated with female sexual behaviour. Together, these results suggest that the effects of male odours are not mediated by a PR‐dependent mechanism. Therefore, we tested the hypothesis that oestrogen receptor (ER)‐containing cells are involved in the effects of olfactory cues. Although there was virtually no coexpression of ERβ and odour‐induced Fos in brain areas associated with female sexual behaviour, exposure to male odours slightly increased the number of cells coexpressing ERα and odour‐induced Fos in the posterodorsal medial amygdala. Although, these results do not support the hypothesis that the effects of odours are mediated by a PR‐dependent mechanism, they suggest that integration of male odours and hormonal cues may occur in ERα‐containing cells in the posterodorsal medial amygdala.
Daily Rhythms in Glucose Metabolism: Suprachiasmatic Nucleus Output to Peripheral Tissue
Authors: La Fleur S. E.
Published: March 2003

The body has developed several control mechanisms to maintain plasma glucose concentrations within strict boundaries. Within those physiological boundaries, a clear daily rhythm in plasma glucose concentrations is present; this rhythm depends on the biological clock, which is located in the hypothalamic suprachiasmatic nucleus (SCN), and is independent of the daily rhythm in food intake. Interestingly, there is also a daily rhythm in glucose uptake, which also depends on the SCN and follows the same pattern as the daily rhythm in plasma glucose concentrations; both rise before the onset of activity. Thus, the SCN prepares the individual for the upcoming activity period in two different ways: by increasing plasma glucose concentrations and by facilitating tissue glucose uptake. In addition to this anticipation of glucose metabolism to expected glucose demands, the SCN also influences, depending on the time of the day, the responses of pancreas and liver to abrupt glucose changes (such as a glucose rise after a meal or hypoglycaemia). This review presents the view that the SCN uses different routes to (i) maintain daily glucose balance and (ii) set the level of the endocrine response to abrupt blood glucose changes.
Speech intelligibility in patients with complete dentures according to the material used
Authors: Foti  , Tavitian  , Bonfil J. ‐J.
Published: March 2003

The principal purpose of this study was to investigate the speech of two edentulous subjects fitted with a complete maxillary prosthesis made of three different palatal materials: aluminium, resin, stellite. The study was performed using two speakers fitted with a prosthesis (a man and a woman). They took part in the acoustic recording of logatoms read by themselves while wearing various prostheses. These recordings were tested from the auditory point of view by a series of six listeners (four men and two women) in an anechoic room. After 144 different tests, a speech reception threshold (SRT) was defined for each speaker and each different prosthesis. This SRT shows a level of speech intelligibility defined so that the lower the SRT, the more intelligible for the listener. The results show that: (i) both the material and the listener influence SRT: (P < 0·05); (ii) an interaction between the material factor and the speaker factor appears. (P < 0·05); (iii) The hierarchy factors influencing SRT are most important in the order: Listener → material → speaker; and (d) The group fitted with a metal prosthesis (aluminium, stellite) was more intelligible regarding the way they were perceived by others.
Autocorrelation of acoustic signals from the temporomandibular joint
Authors: Prinz
Published: March 2003

SUMMARY Although there have been many investigations of TMJ sounds in the time and frequency domains, no previous reports have been found of investigations of the autocorrelation spectra of these sounds. In the present study, TMJ sounds were digitized at 1·7 kHz and 300 ms samples containing either clicks (single short duration sounds), crepitus (long duration continuous sounds) or creaks (a series of two or more clicks) were selected. These samples were compared with sounds of known origin: tooth impact sounds, frictional sounds elicited by scratching the head, and bruxing sounds resulting from stick‐slip friction as teeth were slid against one another under high pressure. There were clear qualitative and quantitative differences between the autocorrelation spectra of the three types of TMJ sounds. Clicks were similar to tooth impact contact sounds, creaks were similar to the bruxing sounds, and crepitus was similar to the scratching sounds. The repetition rate of creaks was 16 Hz (s.d. 9 Hz), this being similar to the resonance of the mandible about the condylar axis. It is suggested that the creaks are due to stick‐slip friction in the lower joint compartment of the TMJ.
Perfusing dentine with horse serum or physiologic saline: its effect on adhesion of dentine bonding agents
Authors: Augustin  , Paul  , Lüthy  , Schärer
Published: March 2003

Freshly prepared dentine specimens of human teeth were perfused with either horse serum or physiologic saline. After application of AllBond2®, ART Bond®, Syntac® or an experimental dentine bonding agent called P‐Bond, a composite cylinder was added and cured at the same time. After 1500 thermal cycles with constant imitation of intrapulpal pressure, the shear bond strengths were measured. Resulting shear bond strength values were analysed with Students t‐test or Mann–Whitney Test. The values for AllBond2® were not significantly different. The values for ART Bond®(P < 0·05) and for Syntac® (P < 0·05) were significantly higher if the dentine was perfused with horse serum. For P‐Bond (P < 0·001) the values were significantly higher if the dentine was perfused with physiologic saline. According to these results it does not seem to be appropriate to take a clear decision as to which of the two perfusing media investigated might be more suitable to imitate in vivo conditions.
Complications and primary failures related to fixed metal ceramic bridge prostheses made by dental students
Authors: Raustia A. M. , Näpänkangas R. , Salonen M. A. M.
Published: March 2003

SUMMARY Porcelain fused to metal provides better aesthetics in fixed partial dentures than veneers with gold‐resin that were used formerly. The aim of our study was to evaluate complications and primary failures of fixed metal ceramic bridge prostheses made by dental students. We studied 61 patients (32 women, 29 men, mean age 49 years, range 28–73 years) treated during years 1990–1993. Data were collected from the patient files. Altogether 82 bridges were made (mean 4·1 units, range 2–6), 221 abutments (mean 2·7, range 2–6) and 136 pontics (mean 1·6, range 1–4). Forty‐seven cast cores were used in 29 bridges (mean 0·4 cores, range 1–3) and semiprecious attachments as an extra attachment in two bridges. Seven teeth were extracted due to complication and/or failure during endodontic treatment and root canal perforation during preparation. In two cases the abutment tooth was fractured by removing the old crown. Four unsuccessful bridges were remade and in seven cases the firing of porcelain was renewed. The study concludes that most common failures of fixed metal ceramic bridges made by dental students occur during root canal preparation of abutment teeth.
A polysomnographic study on masticatory and tongue muscle activity during obstructive and central sleep apnea
Authors: Yoshida
Published: March 2003

Masticatory and tongue muscle activity was examined polysomnographically in 14 patients with sleep apnea syndrome and six snorers. The all‐night polysomnographic recordings included electromyograms (EMG) of the genioglossal, the masseter and the inferior head of the lateral pterygoid muscles, nasal airflow and thoracoabdominal respiratory effort. The apneas were defined and classified into three types (obstructive, central and mixed). EMG amplitudes of each muscle were measured before, during and after the obstructive and central apneas. In the apnea patients the three muscles showed significantly lower EMG amplitudes during the obstructive apnea than before the apnea, and then significantly higher amplitudes after the apnea. These findings indicate that the hypotonia of the muscles during sleep can result in obstructive apnea. There was no significant difference in the pattern of muscle activity during obstructive apnea between the apnea patients and the snorers. On the other hand, a decrease in the mean EMG amplitude during the central apnea was not observed. It is suggested that central apnea occurs independently of masticatory and tongue muscle activity.
Psychometric profiles of temporomandibular disorder patients in southern Thailand
Authors: Sirirungrojying S. , Srisintorn S. , Akkayanont P.
Published: March 2003

summary

Psychological factors of temporomandibular disorder patients are believed to have a significant role in the aetiology and maintenance of the disorders. Sixty‐two temporomandibular disorder patients, 67 dental patients, and 70 asymptomatic subjects were compared for psychometric profile by using a self‐report symptom inventory. Temporomandibular disorder patients were more depressed and anxious than dental patients and asymptomatic subjects, and were also more somatized than asymptomatic subjects.
A visual method for analysing bucco‐lingual position of artificial posterior teeth. Part 1: use of the ridge crest
Authors: Kawahata N. , Kamada Y. , Ohtsuka A. , Kamashita Y. , Nishi Y. , Hamano T. , Nagaoka E.
Published: March 2003

We have developed a visual analysis method to examine the spatial relationship between the edentulous ridges and the bucco‐lingual position of the artificial posterior teeth in complete denture fabrication. In this system, a non‐contact type shape measurement system is used. We applied this system to the plaster models and the wax dentures of an edentulous patient. Using the measurement data on the upper and lower plaster models, we reconstructed their shape three‐dimensionally and determined the points regarded as the ridge crests and the inter‐alveolar crest lines in the frontal sections. To generate the upper and lower ridge crest lines which consisted of the points of the ridge crests, interpolation by B‐spline curves was applied. Furthermore, the loft surfaces that we regarded as the consecutive inter‐alveolar crest lines, were generated between the upper and lower ridge crest lines. The surface models of the plaster models and artificial teeth were displayed on the cathode‐ray tube display unit, and the ridge crest lines and the consecutive inter‐alveolar crest lines were superimposed on the surface models. This method could be utilized to visualize and examine the bucco‐lingual position of the artificial posterior teeth in reference to the inter‐alveolar crest lines.
Consistency of alginate impression materials and their evaluation
Authors: Inoue K. , Song Y. X. , Fujii K. , Kadokawa A. , Kanie T.
Published: March 2003

The apparent viscosity of 17 commercially available alginate impression materials was examined using a rheometer. Each material was mixed for 15 s at a temperature of 23±0·5 °C, using a specially designed alginate mixing instrument. The water powder ratio was determined according to the manufacturer’s instruction. The mixed alginate paste was immediately transferred to the sample stage of the rheometer or to a commercial perforated metal tray. Over the same time scale adjusted according to the rheometer test, a discrimination test (subjective test) was performed by 16 young dentists (each with more than 4 years experience). The apparent viscosity of all materials rose as a function of time after mixing and most of the material had properties similar to pseudoplastic fluids. The relationship between the results of the subjective test and the experimental values (objective test) with the rheometer was expressed in a quadratic equation. The maximum value of the apparent viscosity derived from this result was 1·52×103 Pa · s.
The effect of saliva on fluoride release by a glass–ionomer filling material
Authors: Bell A. , Creanor S. L. , Foye R. H. , Saunders W. P.
Published: March 2003

The initial aim of this study was to investigate the effect of saliva and the formation of pellicle on the fluoride release in vitro of the glass–ionomer filling material, Chemfil Superior®. For the first study glass–ionomer discs of 6 mm in diameter and 1·5 mm thick were made. Ten discs were immersed in whole stimulated saliva each day for 10 min and 10 control discs were immersed in deionized water. For the remaining 23 h and 50 min of each day, over the 20‐day experimental period, both test and control discs were placed in deionized water. A considerable amount of fluoride was released on the first day (14·5 ppm F control and 13·3 ppm F test). The concentration of fluoride released on the second day fell sharply to 5·3 ppm F for controls and 4·9 ppm F for tests. This release had almost reached a plateau by day 10 and at day 20 the pellets continued to release low levels of fluoride. The concentration of fluoride released was only slightly higher for controls than for test discs when both were immersed in deionized water until day 20. However, during the 10‐min period between 1·5 and 2 times as much fluoride was released into the deionized water as into saliva until day 20 when the ratio fell to 1·2:1. The second experiment assessed fluoride release when specimens were incubated for 1 h using an identical protocol. Again, less fluoride was released from the saliva‐coated specimens compared with the controls (17%), which was not substantially different to the comparable 10‐min samples (13%). This study indicates that saliva retards the release of fluoride from glass–ionomer and that this retarding effect is still present when discs are subsequently immersed in water compared with those that were placed in water alone. This suggests that salivary deposits have formed within minutes of immersion in saliva. This retarding effect was observed throughout the study period with the exception of the 20‐day samples which had been incubated in saliva for 10 min.
EMG activity of the orbicularis oris and mentalis muscles in children with malocclusion, incompetent lips and atypical swallowing—Part II
Authors: Tosello D. O. , Vitti M. , Berzin F.
Published: March 2003

The EMG activity of the orbicularis oris (upper and lower), and of the mentalis muscles was verified during several movements of the lips, in 18 children ageing from 8 to 12 years, divided into three groups: one with normal occlusion, and two with class II division 1, with atypical swallowing and/or incompetent lips and who had received no orthodontic treatment. In blowing through a straw the muscular activity of the orbicularis oris and the mentalis was significantly greater in the incompetent lips group. The mentalis presented moderate activity in the competent lips group and negligible in normal occlusion. In puffing out of the cheeks, the malocclusion groups developed marked activity of the orbicularis oris and very marked activity of the mentalis, while the normal occlusion presented moderate and negligible activities, respectively. In pursing of the lips, only the incompetent lips group presented a very marked activity of the lower segment. The compression of the lips against the teeth revealed a marked activity of the upper segment of the orbicularis oris in the groups of malocclusion and the mentalis presented greater activity in the competent lips group. The reciprocal compression of the lips presented a hyperactivity of the three muscles.
The effect of accelerated ageing on the mechanical properties of soft denture lining materials
Authors: Hekimoğlu C. , Anil N.
Published: March 2003

The purpose of this study was to determine the effect of simulated ageing on the physical properties of some soft denture liners. The hardness, tensile strength and percentage elongation values were determined before and after ageing treatment. At the end of the experimental ageing process softening was observed only in Simpa and Ufigel L materials. It was established that ageing had insignificant effect on the hardness of other materials. It can be presumed that there will not be significant time‐related changes in the hardness of these materials. Molloplast B preserved its highest value after the ageing process, whilst that of Simpa decreased to become comparable with Ufigel P.
Initial versus subsequent release of elements from dental casting alloys
Authors: Wataha J. C. , Lockwood P. E. , Nelson S. K.
Published: March 2003

The release of elements from dental casting alloys is directly related to adverse biological effects they may have. Longer‐term (>1 month) studies of elemental release have suggested that release decreases significantly after a higher initial release of elements. The aim of the current study was to measure the release of elements from a variety of clinically relevant dental casting alloys and compare the release at weekly intervals through 4 weeks. The hypothesis was that the release during the initial week should be higher than in subsequent weeks, and that cytotoxicity should decrease as elemental release decreases. Alloy samples were exposed to cell‐culture medium which was changed at weekly intervals and assessed for elemental release by means of atomic absorption spectrometry. The cytotoxicity of the medium was also measured. The results showed that for single phase alloys, initial release was often significantly higher in the first weeks than in subsequent weeks, but not for all elements in an alloy. Multiple phase alloys showed steady or increasing release relative to the first week. Cytotoxicity relationships were complex depending on which elements were released and the ratios of elements released. This study suggests that short‐term tests (<1 week) may not be appropriate to evaluate longer‐term elemental release or cytotoxicity because of changing rates of elemental release.
Interactions between thermal cycled resilient denture lining materials, salivary and serum pellicles and Candida albicansin vitro. Part II. Effects on fungal colonization
Authors: Nikawa H. , Jin C. , Hamada T. , Makihira S. , Kumagai H. , Murata H.
Published: March 2003

In the present study, the growth of a single isolate of Candida albicans on saliva‐, serum‐coated or protein free (uncoated), thermocycled (4–70 °C for 1 min, respectively; 0, 1000 and 10 000 times) seven commercial soft lining materials were investigated, by adenosine triphosphate (ATP) analysis. In the case of control resilient liners (not thermocycled and uncoated), the fungal colonization appeared to depend upon the type of commercial resilient liner used. Thus, the lowest colonization was observed with fluoric and heat‐cured silicone materials, cold‐cured silicone materials, except for one product, and heat‐cured acrylic resin exhibited the highest colonization capacity, and cold‐cured acrylic resilient liners exhibited the intermediate. However, the fungal colonization on the materials was significantly promoted both by thermal cycling (
anova, P<0·01) and a layer of protein coating (saliva, P<0·01; serum, P<0·01). These results, taken together, suggest that the ageing of the materials and the biological fluids of the host promote yeast colonization on resilient lining materials.
Effects of acids and additives on the susceptibility of human dentine to denaturation
Authors: Agee K. , Zhang Y. , Pashley D. H.
Published: March 2003

The purpose of this study was to evaluate the efficacy of a number of additives to acid conditioners at reducing the denaturation of dentine collagen. Dentine collagen is normally not very susceptible to trypsin attack. After denaturation, however, it becomes more susceptible to the action of trypsin. Slabs of human dentine were dipped in water or acidic conditioners (10% citric acid or 37% phosphoric acid) containing no additives, 5 or 10% NaCl, 3 or 6% ferric chloride or 50% hydroxyethylmethacrylate (HEMA) for 15 or 60 s, followed by rinsing. The slabs were then exposed to trypsin for 24 h to solubilize any denatured collagen. The solubilized collagen was hydrolysed to liberate hydroxyproline that was quantitated spectrophotometrically. The amount of hydroxyproline (HOP) liberated was indicative of the amount of dentine collagen that was denatured by the test solutions. The only additive that consistently reduced HOP release was 50% HEMA, and this only occurred in the 60 s exposure group. Thus, the use of salt additives to acidic conditioners has little protective effect.
Shear bond strength of resin teeth to heat‐cured and light‐cured denture base resin
Authors: Cunningham J. L.
Published: March 2003

The failure of the bond between acrylic resin teeth and denture base material remains a considerable problem. Previous research has indicated that the introduction of a bonding agent to the tooth–resin interface significantly increased the tensile bond strength. To further investigate this finding, and to complement the earlier study, a shear strength assessment was carried out. Both a commercial and an experimental bonding agent were evaluated for tooth retention when applied to heat‐cured and visible light‐cured (VLC) resin. A significant increase in shear bond strength was obtained when bonding agents were applied. The experimental cement gave the greatest increase in strength, although the VLC resin failed to achieve the same degree of tooth attachment as the heat‐cured resin.
Generalized joint laxity and its relation with oral habits and temporomandibular disorders in adolescent girls
Authors: Winocur E. , Gavish A. , Halachmi M. , Bloom A. , Gazit E.
Published: March 2003

A group of 248 girls, aged 15–16 years, were randomly selected and examined both clinically and by questionnaire with regard to the signs and symptoms of temporomandibular disorders (TMD), generalized joint laxity (GJL), range of mandibular opening, temporomandibular joint (TMJ) hypermobility and presence of oral parafunctions. The prevalence of GJL was 43% and that of TMJ hypermobility (TMJH) was 27.3%. A significant, albeit weak, correlation was found between the two. In the presence of joint click, both active and passive opening were significantly larger. When either muscle or joint sensitivity to palpation was present, the difference between the active and passive range of mouth opening increased significantly. The presence of reported clicks was negatively associated with GJL. This association was not valid in the presence of parafunction. Some of the signs and symptoms of TMD affected the range of mouth opening. In the presence of joint clicks, the mean active and passive mandibular opening were significantly larger. In the presence of joint and muscle sensitivity to palpation, the difference between passive and active mouth opening was larger. This was possibly because of the effect of pain on the full active range of opening, which was invalid in the registration of the passive mandibular opening. GJL, when present, did not seem to jeopardize the health of the stomatognathic system as expressed in the signs and symptoms of TMD. There was a negative association between GJL and the presence of reported joint clicks and catch. When a parafunction was present in addition to GJL, this association was invalid but not reversed, as has been previously reported.
Effect of dental metal ions on glutathione levels in THP‐1 human monocytes
Authors: Wataha J. C. , Lewis J. B. , Lockwood P. E. , Rakich D. R.
Published: March 2003

The release of metal ions from dental restorations has been well established, but the sublethal effects of these ions on oral tissues remain undefined. Metal ions are a potential cause of sublethal oxidative stress in cells. Oxidative stress is known to alter cellular processes which are important in the inflammation of tissues. The presence of oxidative stress is commonly assessed by measuring the oxidized (GSSG) and reduced (GSH) forms of cellular glutathione. Normally, the majority of cellular glutathione exists as GSH and the GSH–GSSG ratio is high. Since monocytes often orchestrate inflammatory responses, oxidative stress in monocytes is important. Our hypothesis for the current work was that metal ions induce oxidative stress in monocytes which is manifested by a lower GSH–GSSG ratio. Human THP‐1 monocytes were exposed for 24 h to sublethal concentrations of ions of Ag, Be, Co, Cu, Hg, Ni, Pd, and Zn – all known to be released from dental biomaterials. GSH and GSSG were measured using colorimetric assays. Cu lowered the GSH–GSSG ratio as hypothesized, but the ratio could not be determined for other metals because other metal ions interfered with the GSSG assay. However, a statistically significant ( anova/Tukey) increase in GSH per cell was observed upon exposure to Ag (50%), Co (100%), Hg (250%) and Zn (10%). This increase may be indicative of an oxidative stress in its own right. Alterations in GSH levels may be important to how released metal ions alter cytokine secretion from monocytes and other cells which play a role in the inflammatory response to dental biomaterials.