bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of smoking on periodontal treatment response: a review of clinical evidence
Authors: Heasman L. , Stacey F. , Preshaw P. M. , McCracken G. I. , Hepburn S. , Heasman P. A.
Published: March 2006

Background: Smoking has been identified as a significant risk factor for periodontal diseases and is regarded as being responsible for incomplete or delayed healing in patients following treatment.

Aim and Method: The aim of this conventional review was to review, collate and tabulate the relative effectiveness of treatments of chronic periodontitis in smokers, non‐smokers and ex‐smokers.

Observations: The majority of clinical trials show significantly greater reductions in probing depths and bleeding on probing, and significantly greater gain of clinical attachment following non‐surgical and surgical treatments in non‐smokers compared with smokers. This benefit is also seen at class I and II furcation sites and in patients prescribed systemic or local antimicrobial treatments.

Conclusions: Data from epidemiological, cross‐sectional and case–control studies strongly suggest that quitting smoking is beneficial to patients following periodontal treatments. The periodontal status of ex‐smokers following treatment suggests that quitting the habit is beneficial although there are only limited data from long‐term longitudinal clinical trials to demonstrate unequivocally the periodontal benefit of quitting smoking.
Tooth loss in treated periodontitis patients responsible for their supportive care arrangements
Authors: Leung W. K. , Ng Daniel K. C. , Jin Lijian , Corbet Esmonde F.
Published: March 2006

Aim: To identify risk indicators associated with tooth loss and periodontitis in treated patients responsible for arranging supportive periodontal care (SPC).

Materials and Methods: Ninety‐seven Chinese subjects (34–77 years) who showed favourable responses to periodontal therapy provided in a teaching hospital 5–12 years previously were recalled. They were advised to seek regular SPC on discharge. Background information, general health status, smoking, oral hygiene habits, follow‐up dental care, tooth loss, and periodontal parameters were investigated. Multiple regression analysis was performed.

Results: Two hundred and fifty‐six teeth had been lost, 195 because of self‐reported periodontal reasons. Up to 26.8% sites were with pockets 6 mm. Positive correlations were found between total/periodontal tooth loss and (i) smoking pack‐years, (ii) time spent on oral hygiene, (iii) years since therapy's conclusion, (iv) age, and negative correlations with (v) inter‐dental brush use, and (vi) education levels. Tooth loss by arch was correlated with wearing of removable partial denture in that arch. Percentage sites with pockets 6 mm were significantly negatively correlated with percentage sites without bleeding on probing.

Conclusions: Smokers, more elderly patients, removable partial denture wearers, and patients with lower education levels or not using inter‐dental brushes ought to be targeted for clinic‐based SPC.
Cathepsin K levels in the crevicular fluid of dental implants: a pilot study
Authors: Strbac Georg D. , Monov Gabriel , Cei Silvia , Kandler Barbara , Watzek Georg , Gruber Reinhard
Published: March 2006

Objective: To determine the concentration of cathepsin K secreted into the crevicular fluid around dental implants and its correlation with clinical parameters of healthy implants and implants showing clinical signs of peri‐implantitis.

Material and Methods: Nineteen patients with 40 implants with and without peri‐implantitis were enrolled in the study. Peri‐implantitis was diagnosed by the pocket probing depth (PD), the modified bleeding index (MBI), the modified plaque index (MPI) and by radiographic signs of bone loss. Gingival crevicular fluid collected from the buccal and lingual sites was adsorbed to filter strips. Cathepsin K levels and total protein within the crevicular fluid were determined by immunoassay and the bicinchoninic method, respectively.

Results: Cathepsin K per filter strip normalized to the time of collection was 10.1 (0–33.5) pmol/sample around control implants and 22.4 (3.7–56.3) pmol/sample in the peri‐implantitis group. The difference between the medians was significant (p<0.01). Absolute cathepsin K levels in the crevicular fluid of all implants investigated showed a positive correlation with PD (R=0.25; p=0.03), MPI (R=0.28; p=0.01) and MBI (R=0.32; p<0.01). Absolute cathepsin K levels in the crevicular fluid also correlated with the adsorbed volume of gingival crevicular fluid (R=0.51; p<0.01). When normalized to the adsorbed volume of gingival crevicular fluid, the concentration of cathepsin K was 2.2 (0.01–6.4) nM around control implants and 1.7 (0.4–4.6) nM in the peri‐implantitis group (p=0.33). Patients' age correlated with sample volume and with cathepsin K normalized to the adsorbed volume of gingival crevicular fluid (R=0.39; p<0.01). Moreover, significant differences between male and female (p<0.01, p<0.01), and between mandible and maxilla (p<0.05, p<0.01), but not between buccal and lingual sites (p=0.99, p=0.93), were observed when analysed for the parameters adsorbed volume and absolute cathepsin K levels.

Conclusion: Clinical parameters of peri‐implantitis are associated with a higher amount of cathepsin K and a higher volume adsorbed to filters strips. To establish cathepsin K as a biochemical parameter to monitor peri‐implant tissue health, age, sex and collection site should be considered to avoid interfering influences because of sample inhomogenity. Also a prospective study over time including more patients would be necessary.
Clinical and microbiological effects of different antimicrobials on generalized aggressive periodontitis
Authors: Xajigeorgiou Christiana , Sakellari Dimitra , Slini Theodora , Baka Anneta , Konstantinidis Antonis
Published: March 2006

Aim: To evaluate and compare the effects of adjunctive metronidazole plus amoxicillin, doxycycline and metronidazole on clinical and microbiological parameters in patients with generalized aggressive periodontitis.

Material and Methods: Forty‐three patients participated in this randomized clinical trial divided into four groups. Six weeks after scaling and root planning (SRP), groups 1–3 received adjunctive metronidazole, plus amoxicillin, doxycycline and metronidazole respectively, and group 4 acted as controls. Clinical recordings concerning probing depth, probing attachment level and bleeding on probing were performed at baseline, 6 weeks after SRP and 6 months from baseline. Subgingival samples were analysed using the ‘checkerboard’ DNA–DNA hybridization for Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Tannerella forsythia and Treponema denticola.

Results: All treatments resulted in improvement of clinical parameters (ANOVA p>0.05). Systemic administration of metronidazole plus amoxicillin or metronidazole resulted in statistically significant greater reduction of the proportion of sites > 6mm than SRP (z‐test, p<0.05). These antimicrobials yielded a significant effect on levels of important periodontal pathogens for 6 months.

Conclusion: Adjunctive metronidazole plus amoxicillin or metronidazole alone (when A.actinomycetemcomitans is not involved) is effective in deep pockets of aggressive periodontitis patients.
Nine‐ to fourteen‐year follow‐up of implant treatment. Part II: presence of peri‐implant lesions
Authors: Roos‐Jansåker Ann‐Marie , Lindahl Christel , Renvert Helena , Renvert Stefan
Published: March 2006

Objectives: The aim of this study was to analyse the proportions of peri‐implant lesions at implants after 9–14 years of function.

Material and Methods: Two hundred and ninety‐four patients underwent implant therapy during the years 1988–1992 in Kristianstad County. These individuals were recalled to the speciality clinic 1 and 5 years after placement of the suprastructure. Between 2000 and 2002, 218 patients with 999 implants were examined clinically and radiographically.

Results: Forty‐eight per cent of the implants had probing depth 4 mm and bleeding on probing (peri‐implant mucositis). In 20.4% of the implants, the bone level was located 3.1 mm apical to the implant shoulder. Progressive bone loss (1.8 mm) during the observation period was found in 7.7% of the implants. Peri‐implantitis defined as bone loss 1.8 mm compared with 1‐year data (the apical border of the bony defect located at or apical to the third thread, i.e. a minimum of 3.1 mm apical to the implant shoulder), combined with bleeding on probing and or pus, were diagnosed among 16% of the patients and 6.6% of the implants.

Conclusion: After 10 years in use without systematic supportive treatment, peri‐implant lesions is a common clinical entity adjacent to titanium implants.
Nine‐ to fourteen‐year follow‐up of implant treatment. Part I: implant loss and associations to various factors
Authors: Roos‐Jansåker Ann Marie , Lindahl Christel , Renvert Helena , Renvert Stefan
Published: March 2006

Objectives: The aim of the present study was to evaluate the long‐term result of implant therapy, using implant loss as outcome variable.

Material and Method: Two hundred and ninty‐four patients had received implant therapy (Brånemark System®) during the years of 1988–1992 in Kristianstad County, Sweden. The patients were recalled to the speciality clinic 1 and 5 years after placement of the suprastructure. Between 2000 and 2002, 9–14 years after implant placements, the patients were again called in for a complete clinical and radiographic examination.

Results: Two hundred and eighteen patients treated with 1057 implants were examined. Twenty‐two patients had lost 46 implants and 12 implants were considered “sleeping implants”. The overall survival rate was 95.7%. Implant loss appeared in a cluster in a few patients and early failures were most common. Eight patients lost more than one fixture. A significant relationship was observed between implant loss and periodontal bone loss of the remaining teeth at implant placement. Maxillary, as opposed to mandibulary implants, showed more implant loss if many implants were placed in the jaw. A significant relationship between smoking habits and implant loss was not found.

Conclusion: A history of periodontitis seems to be related to implant loss.
Nine‐ to fourteen‐year follow‐up of implant treatment. Part III: factors associated with peri‐implant lesions
Authors: Roos‐Jansåker Ann‐Marie , Renvert Helena , Lindahl Christel , Renvert Stefan
Published: March 2006

Objective: The aim of the present paper was to analyse, on patient and implant basis, factors related to peri‐implant lesions.

Material and Methods: Two hundred and eighteen patients treated with titanium implants were examined for biological complications at existing implants 9–14 years after initial therapy. The effects of several potentially explanatory variables, both on patient and on implant levels, were analysed.

Results: On the implant level, the presence of keratinized mucosa (p=0.02) and plaque (p=0.005) was associated with mucositis (probing depth 4 mm+bleeding on probing). The bone level at implants was associated with the presence of keratinized mucosa (p=0.03) and the presence of pus (p<0.001). On the patient level, smoking was associated with mucositis, bone level and peri‐implantitis (p=0.02, <0.001 and 0.002, respectively). Peri‐implantitis was related to a previous history of periodontitis (p=0.05).

Conclusions: Individuals with a history of periodontitis and individuals who smoke are more likely to develop peri‐implant lesions.
A case of hepatosplenic γ–δ T‐cell lymphoma with a transient response to Fludarabine and Alemtuzumab
Authors: Mittal S. , Milner B. J. , Johnston P. W. , Culligan D. J.
Published: March 2006

Abstract:  Hepatosplenic γ–δ T‐cell lymphoma is a rare, usually fatal lymphoma and available literature on management is sparse. Allografting is probably the only curative option. We describe a further case with a dramatic, though transient response to Fludarabine and Alemtuzumab combination, following a failure of conventional chemotherapy. Given the dreadful prognosis with conventional chemotherapy, it is a regimen worth pursuing as a disease reduction strategy prior to allograft where appropriate.
Multiple joint effusions associated with high‐dose imatinib therapy in a patient with chronic myelogenous leukaemia
Authors: Moore James C. , Dennehey Carolyn F. , Anavim Arash , Kong Kevin M. , Tiong Ong S.
Published: March 2006

Abstract:  Imatinib mesylate is a small molecule tyrosine kinase inhibitor that has significant efficacy in the treatment of chronic myelogenous leukaemia (CML). However, it is likely that patients with CML will require prolonged and perhaps life‐long therapy. In general, the side‐effects of imatinib therapy have been mild to moderate, with the large majority of patients tolerating prolonged periods of therapy. However, a minority of patients are completely intolerant of therapy, while others are able to remain on therapy despite significant side‐effects. Here, we describe a novel form of fluid retention presenting as multiple joint effusions in a patient with advanced phase CML on high‐dose imatinib, as well as successful measures that were undertaken to control this adverse event. Although fluid retention, including periorbital oedema, pleural and pericardial effusions, as well as life‐threatening cerebral oedema have been previously described and attributed to imatinib, this is the first case of imatinib‐associated polyarticular effusions that we are aware of. Further work will be required to confirm a casual relationship between imatinib therapy and this novel side‐effect, as well as to determine the underlying pathophysiologic mechanisms.
Effects of Dynactin Disruption and Dynein Depletion on Axonal Microtubules
Authors: Ahmad Fridoon J. , He Yan , Myers Kenneth A. , Hasaka Thomas P. , Francis Franto , Black Mark M. , Baas Peter W.
Published: March 2006

We investigated potential roles of cytoplasmic dynein in organizing axonal microtubules either by depleting dynein heavy chain from cultured neurons or by experimentally disrupting dynactin. The former was accomplished by siRNA while the latter was accomplished by overexpressing P50‐dynamitin. Both methods resulted in a persistent reduction in the frequency of transport of short microtubules. To determine if the long microtubules in the axon also undergo dynein‐dependent transport, we ascertained the rates of EGFP‐EB3 “comets” observed at the tips of microtubules during assembly. The rates of the comets, in theory, should reflect a combination of the assembly rate and any potential transport of the microtubule. Comets were intitally slowed during P50‐dynamitin overexpression, but this effect did not persist beyond the first day and was never observed in dynein‐depleted axons. In fact, the rates of the comets were slightly faster in dynein‐depleted axons. We conclude that the transient effect of P50‐dynamitin overexpression reflects a reduction in microtubule polymerization rates. Interestingly, after prolonged dynein depletion, the long microtubules were noticeably misaligned in the distal regions of axons and failed to enter the filopodia of growth cones. These results suggest that the forces generated by cytoplasmic dynein do not transport long microtubules, but may serve to align them with one another and also permit them to invade filopodia.
Factors affecting treatment outcomes following complicated crown fractures managed in primary and secondary care
Authors: Jackson N. G. , Waterhouse P. J. , Maguire A.
Published: March 2006

Abstract –  The aims of this retrospective observational study were to determine the factors which affect treatment provision and the Median Survival Time (MST) for maintenance of tooth vitality following complicated crown fracture. The survey was carried out for patients treated at Newcastle Dental Hospital (NDH) according to departmental guidelines over a 2‐year period following the introduction of a new protocol for management of these types of injuries. Seventy‐three cases of complicated crown fracture were identified in 69 children with a mean age of 10.3 years (SD = 2.5 years). Seventy‐one percent of the fractures occurred in males (M:F ratio was 2.5:1). Fifty‐one percent of the complicated crown fractures were in immature teeth. Of the 73 traumatised teeth, 45% presented initially in general dental practice (GDP), 37% at the dental hospital and 8% at local accident and emergency departments with the remaining 10% seen at other or unrecorded locations. Of the 41 fractures, which presented initially at a location other than the dental hospital, 38% were referred to the dental hospital without the provision of an emergency pulp bandage. The overall definitive treatments provided for the 37 open apex teeth included pulp cap (19%), partial pulpotomy (32%), cervical pulpotomy (8%) and pulpectomy (35%), while for the 36 closed apex teeth it was pulp cap (28%), pulpotomy (11%), and pulpectomy (61%). Of the 30 teeth, which underwent vital pulp therapy (18 open and 12 closed apex), the MST for the 15 teeth treated with pulp caps was 1460 days (95% CI: 1067, 1853) while for the 15 teeth treated with pulpotomies it was 1375 days (95% CI: 964, 1786). There was no statistically significant difference in the MST between teeth treated with pulp caps and pulpotomies. In conclusion, the proportion of patients referred to secondary care with complicated crown fractures without provision of a pulp bandage is of some concern. More conservative treatment of closed apex teeth sustaining complicated crown fractures, utilizing vital pulp therapy techniques would appear to be appropriate.
Adhesive strength and its improvement referring to the laminated‐type mouthguard
Authors: Takeda Tomotaka , Ishigami Keiichi , Kawamura Shintaro , Nakajima Kazunori , Shimada Atsushi , Sumii Toshio , Swain Michael
Published: March 2006

Abstract –  The manufacture of laminated‐type mouthguards requires skill in fusing sheets of mouthguard materials together. Adequate adhesive strength is required to use mouthguards in a stable condition for a long time. Therefore, in this study, the exfoliation test was applied and some treating techniques and conditions that improve the adhesive strength on a laminated surface were examined. Samples were laminated with two pieces of mouthguard material (3 mm thickness) having an adhesive area of 5 × 5 mm2, and whose other end was the holding part. The experimental factors used were as follows: heating time, use of solvent, elimination and direct heating of the laminate surface, colour of materials and water sorption. The result was measured at the time of breakage of the maximum load (N) and the form of destruction was examined. At 165 s of heating time, material failure was shown at under a load exceeding 5.0 N when compared to an untreated condition. Material failure was measured when a solvent was used and during the elimination of the laminated surface at a heating time of 150 s, which is 15 s lesser than in an untreated condition. Material failure was also measured by direct heating on the bonding surface of a second sheet of material at a heating time of 135 s, which is 30 s lesser than in an untreated condition. The differences in colour of the materials influence adhesion. Clear and light coloured materials showed higher adhesion ability. One‐way analysis of variance confirmed a statistically significant difference in heating time differences, usage of solvent, elimination, direct heating on bonding surface and colour (P < 0.05). The decrease of adhesive strength by water sorption at 23° and 37°C was not observed significantly. Maximal laminated bond strength can be obtained by minimal heating time and proper treatment with the use of solvent, elimination and direct heating on bonding surface. The differences in the colour of the materials influenced adhesion. Clear and light coloured materials showed higher adhesive ability. Water sorption did not affect the adhesive strength. Therefore, if laminated‐type mouthguards were manufactured properly, it can be used for a longer time and in a good condition.
Joseph Conrad Criticism
Authors: Peters John G.
Published: March 2006

Article

This essay is a brief survey of the history of commentary on the life and works of Joseph Conrad. Beginning with some of the early shorter and extended commentaries that appeared during the second decade of the twentieth century and ending with some of the most recent commentaries, this overview is intended to give the reader a clear idea of the significant issues that have arisen in the study of Conrad’s life and works. During the course of this essay, dominant movements will appear in Conrad studies: biographical/historical studies appearing during the 1920s and 1930s, psychological studies appearing during the 1950s and 1960s, poststructural and postcolonial studies appearing during the 1980s and 1990s, and gender studies appearing more recently. Furthermore, important individual commentaries will also be considered, so that the reader will have a good idea of where to go to investigate further various issues regarding Conrad’s life and works.
Making Time: Narrative Temporality in Twentieth‐Century Literature and Theory
Authors: Richardson Brian
Published: March 2006

This essay attempts to provide a brief survey of twentieth‐century constructions of narrative time in modernist, avant‐garde, and postmodern works and outlines the various theoretical positions these texts have engendered. Beginning with standard modernist practices that present a temporally scrambled story for the reader to reconstitute, I go on to identify some less well known but equally experimental uses of linear temporal order. This is followed by accounts more extreme, nonrealistic constructions of time in avant‐garde, postmodern, and science fiction texts. I conclude with an assessment of standard theories of narrative temporality and a brief look at current work in the field, including attempts to articulate the differing temporalities of serial, postmodern, gay, and postcolonial narratives.
Spoon River Anthology’s Heterosexual Heartland
Authors: Herring Scott
Published: March 2006

Critics often assume Edgar Lee Masters’s best‐selling 1915 collection of poems, Spoon River Anthology, to be a damning account of small‐town corruption and sexual degeneration. This essay argues the counter‐intuitive claim that the anthology instead confirms a pastoral image of small town life even as it appears to negate this ideal. I suggest that Spoon River Anthology paradoxically confirms the idyllic image of the small Midwestern town through the collection’s representations of adultery, unrestrained lust, and promiscuity – activities that were often associated with an “unnatural” version of heterosexuality in the early twentieth‐century United States. To show that Masters’s critical account of Spoon River’s citizenry serves to substantiate representations of the heartland as an idyllic space for opposite‐sex couplings, I offer close readings of two poems –“Lucinda Matlock” and “Washington McNeely”– and illustrate how they each present readers with compulsory versions of heterosexual couplings that contrast to the “deviant” opposite‐sex activities that saturate the remainder of the text.
HLA class II genetic diversity in southern Tunisia and the Mediterranean area
Authors: Abdennaji Guenounou B. , Loueslati B. Yacoubi , Buhler S. , Hmida S. , Ennafaa H. , Khodjet‐Elkhil H. , Moojat N. , Dridi A. , Boukef K. , Ben Ammar Elgaaied A. , Sanchez‐Mazas A.
Published: March 2006

North Africa is populated by many Arab‐ and Berber‐speaking populations whose genetic history is still poorly understood. In this study, we analyse the HLA‐DRB1 and DQB1 molecular diversity in three populations from the south of Tunisia — Berbers from Jerba, Berbers from Matmata and Arabs from Gabes — and we compare them to a large set of populations from the whole Mediterranean region. Among the three populations studied, the Berbers from Jerba are the most peculiar, as they diverge significantly from other North Africans while being genetically highly diversified and close to populations from the Near East. Thus, Jerba may have been a crossing point, in historical times, where colonization from the eastern Mediterranean area left significant genetic traces. By contrast, the populations from Matmata and Gabes are genetically similar to other Arab and Berber‐speaking populations from different areas of the Maghrib, despite some peculiar allele and haplotype frequencies. At a larger scale, northwest Africa and southwest Europe are closely related according to these polymorphisms, while the populations from the eastern Mediterranean area are much more differentiated. The close genetic relatedness found for HLA among populations of the western Mediterranean region challenges previous results based on Y chromosome analyses, where the Gibraltar Strait appeared to constitute a main genetic barrier.
Exercise‐induced alterations in extracellular signal‐regulated kinase 1/2 and mammalian target of rapamycin (mTOR) signalling to regulatory mechanisms of mRNA translation in mouse muscle
Authors: Williamson David L. , Kubica Neil , Kimball Scot R. , Jefferson Leonard S.
Published: March 2006

The present study examined the effects of an acute bout of treadmill exercise on signalling through the extracellular signal‐regulated kinase (ERK)1/2 and mammalian target of rapamycin (mTOR) pathways to regulatory mechanisms involved in mRNA translation in mouse gastrocnemius muscle. Briefly, C57BL/6 male mice were run at 26 m min−1 on a treadmill for periods of 10, 20 or 30 min, then the gastrocnemius was rapidly removed and analysed for phosphorylation and/or association of protein components of signalling pathways and mRNA translation regulatory mechanisms. Repression of global mRNA translation was suggested by disaggregation of polysomes into free ribosomes, which occurred by 10 min and was sustained throughout the time course. Exercise repressed the mTOR signalling pathway, as shown by dephosphorylation of the eukaryotic initiation factor (eIF)4E‐binding protein‐1 (4E‐BP1), enhanced association of the regulatory‐associated protein of mTOR with mTOR, and increased assembly of the tuberin–hamartin complex. In contrast, exercise caused no change in phosphorylation of either Akt/PKB or tuberin. Upstream of mTOR, exercise was associated with an increase in cAMP, protein kinase A activity, and AMP‐activated protein kinase phosphorylation. Simultaneously, exercise caused a rapid and sustained activation of the MEK1/2–ERK1/2–p90RSK pathway, resulting in increased phosphorylation of downstream targets including eIF4E and the ribosomal protein (rp)S6 on S235/S236. Overall, the data are consistent with exercise‐induced repression of mTOR signalling and global rates of mRNA translation, accompanied perhaps by up‐regulated translation of selected mRNAs through regulatory mechanisms such as eIF4E and rpS6 phosphorylation, mediated by activation of the ERK1/2 pathway.
Glucocorticoid effects on mouse microvascular endothelial barrier permeability are brain specific
Authors: Förster Carola , Waschke Jens , Burek Malgorzata , Leers Jörg , Drenckhahn Detlev
Published: March 2006

Endothelial cells (ECs) from different vascular beds display certain common qualities, but each subtype is uniquely adapted to meet the demands of the underlying tissues. The structural peculiarities of intercellular junctions are, for instance, considered to account for the differences in permeability displayed by various vascular beds: strong occludin expression is unique to cerebral ECs and considered to account for the high electrical resistance and low paracellular permeability of brain microvessels which constitute the blood–brain barrier (BBB). The integrity of the BBB is compromised in many disorders of the human CNS; therapeutic strategies include treatment with glucocorticoids (GCs), which improve barrier properties of the BBB. In contrast, positive effects of GCs on peripheral vascular permeability could not be demonstrated clearly, while side‐effects of prolonged GC treatment are considerable. In an effort to elucidate this difference, we analysed the expression of occludin and the glucocorticoid receptor (GR) in BBB and non‐BBB (myocardium) endothelial cells. Our results demonstrate complete GR downregulation by GCs in murine non‐BBB endothelial cells in vivo, whereas GC administration led to nuclear concentration of GRs in BBB endothelium. In correlation with these in vivo data, the use of cerebral and myocardial endothelial cell lines proved GR downregulation in non‐BBB cells in vitro in response to GC treatment. Divergent transactivating activity of GRs in the BBB and non‐BBB endothelial cellular context could be demonstrated after transfection of endothelial cells with a model GC‐responsive test promoter plasmid in the presence and absence of dexamethasone. Our results thus suggest differential signalling mechanisms involved in endothelial barrier regulation, arguing for the development of tissue‐specific drugs for therapeutic applications.
Differential inhibition by hyperglycaemia of shear stress‐ but not acetylcholine‐mediated dilatation in the iliac artery of the anaesthetized pig
Authors: Kelly R. , Ruane‐O'Hora T. , Noble M. I. M. , Drake‐Holland A. J. , Snow H. M.
Published: March 2006

Clinical hyperglycaemia affects vascular endothelial function, but the effect on shear stress‐induced arterial dilatation has not yet been established. We hypothesized that hyperglycaemia would inhibit this response via impaired glycocalyx mechanotransduction. Experiments were carried out in the anaesthetized pig in which pressure, blood flow and diameter of the left iliac artery were measured at two sites: proximal (d1) and distal (d2). Infusion of glucose, sufficient to raise blood glucose to 16–30 mm along the whole length of the artery, attenuated the shear stress‐dependent dilatation in both sections of the artery with preservation of the responses to acetylcholine. The distal site was then isolated using snares and the lumen exposed to blood containing 25–35 mm glucose for 20 min. In the control situation, after exposure of both sections to normoglycaemia (5.7 mm glucose), both sections of artery showed increases in diameter in response to shear stress and acetylcholine. Hyperglycaemia attenuated the shear stress‐dependent dilatation in the distal section only (P < 0.25), but not the response to acetylcholine. It is concluded from these results that the hyperglycaemia‐impaired dilatation is consistent with loss of mechanotransducing properties of the endothelial glycocalyx by hyperglycaemia. These findings offer a possible explanation for the increased incidence of vascular disease in diabetic patients.
Dual mechanisms of angiotensin‐induced activation of mouse sympathetic neurones
Authors: Ma X. , Bielefeldt K. , Tan Z. Y. , Whiteis C. A. , Snitsarev V. , Abboud F. M. , Chapleau M. W.
Published: March 2006

Ang II directly activates neurones in sympathetic ganglia. Our goal was to define the electrophysiological basis of this activation. Neurones from mouse aortic–renal and coeliac ganglia were identified as either ‘tonic’ or ‘phasic’. With injections of depolarizing currents, action potentials (APs) were abundant and sustained in tonic neurones (TNs) and scarce or absent in phasic neurones (PNs). Resting membrane potentials were equivalent in TNs (−48 ± 2 mV, n= 18) and PNs (−48 ± 1 mV, n= 23) while membrane resistance was significantly higher in TNs. Ang II depolarized and increased membrane resistance equally in both TNs (n= 8) and PNs (n= 8) but it induced APs only in TNs, and enhanced current‐evoked APs much more markedly in TNs (P < 0.05). The AT1 receptor antagonist losartan (2 μm, n= 6) abolished all responses to Ang II, whereas the AT2 receptor blocker PD123,319 had no effect. The transient K+ current (IA), which was more than twice as large in TNs as in PNs, was significantly inhibited by Ang II in TNs only whereas the delayed sustained K+ current (IK), which was comparable in both TNs and PNs, was not inhibited. M currents were more prominent in PNs and were inhibited by Ang II. The IA channel blocker 4‐aminopyridine triggered AP generation in TNs and prevented the Ang II‐induced APs but not the depolarization. Blockade of M currents by oxotremorine M or linopirdine prevented the depolarizing action of Ang II. The protein kinase C (PKC) inhibitor H7 (10 μm, n= 9) also prevented the Ang II‐induced inhibition of IA and the generation APs but not the depolarization nor the inhibition of M currents. Conversely, the PKC agonist phorbol 12‐myristate 13‐acetate mimicked the Ang II effects by triggering APs. The results indicate that Ang II may increase AP generation in sympathetic neurones by inducing a PKC‐dependent inhibition of IA currents, and a PKC‐independent depolarization through inhibition of M currents. The differential expression of various K+ channels and their sensitivity to phosphorylation by PKC may determine the degree of activation of sympathetic neurones and hence may influence the severity of the hypertensive response.
Activity‐dependent regulation of voltage‐gated Na+ channel expression in Mat‐LyLu rat prostate cancer cell line
Authors: Brackenbury William J. , Djamgoz Mustafa B. A.
Published: March 2006

We have shown previously that voltage‐gated Na+ channels (VGSCs) are up‐regulated in human metastatic disease (prostate, breast and small‐cell lung cancers), and that VGSC activity potentiates metastatic cell behaviours. However, the mechanism(s) regulating functional VGSC expression in cancer cells remains unknown. We investigated the possibility of activity‐dependent (auto)regulation of VGSC functional expression in the strongly metastatic Mat‐LyLu model of rat prostate cancer. Pretreatment with tetrodotoxin (TTX) for 24–72 h subsequently suppressed peak VGSC current density without affecting voltage dependence. The hypothesis was tested that the VGSC auto‐regulation occurred via VGSC‐mediated Na+ influx and subsequent activation of protein kinase A (PKA). Indeed, TTX pretreatment reduced the level of phosphorylated PKA, and the PKA inhibitor KT5720 decreased, whilst the adenylate cyclase activator forskolin and the Na+ ionophore monensin both increased the peak VGSC current density. TTX reduced the mRNA level of Nav1.7, predominant in these cells, and VGSC protein expression at the plasma membrane, although the total VGSC protein level remained unchanged. TTX pretreatment eliminated the VGSC‐dependent component of the cells' migration in Transwell assays. We concluded that the VGSC activity in Mat‐LyLu rat prostate cancer cells was up‐regulated in steady‐state via a positive feedback mechanism involving PKA, and this enhanced the cells' migratory potential.
Development of Elastic Forces for a Large Deformation Plate Element Based on the Absolute Nodal Coordinate Formulation
Authors: Mikkola Aki M. , Matikainen Marko K.
Published: March 2006

Dynamic analysis of large rotation and deformation can be carried out using the absolute nodal coordinate formulation. This formulation, which utilizes global displacements and slope coordinates as nodal variables, make it possible to avoid the difficulties that arise when a rotation is interpolated in three-dimensional applications. In the absolute nodal coordinate formulation, a continuum mechanics approach has become the dominating procedure when elastic forces are defined. It has recently been perceived, however, that the continuum mechanics based absolute nodal coordinate elements suffer from serious shortcomings, including Poisson’s locking and poor convergence rate. These problems can be circumvented by modifying the displacement field of a finite element in the definition of elastic forces. This allows the use of the mixed type interpolation technique, leading to accurate and efficient finite element formulations. This approach has been previously applied to two- and three-dimensional absolute nodal coordinate based finite elements. In this study, the improved approach for elastic forces is extended to the absolute nodal coordinate plate element. The introduced plate element is compared in static examples to the continuum mechanics based absolute nodal coordinate plate element, as well as to commercial finite element software. A simple dynamic analysis is performed using the introduced element in order to demonstrate the capability of the element to conserve energy.
Active Noise Control Using Phase-Compensated, Damped Resonant Filters
Authors: Bisnette Jesse B. , Smith Adam K. , Vipperman Jeffrey S. , Budny Daniel D.
Published: March 2006

An active noise control device called active noise absorber or ANA, which is based upon damped, resonant filters is developed and demonstrated. It is similar to structural positive position feedback (PPF) control, with two exceptions: (1) Acoustic transducers (microphone and speaker) cannot be truly collocated, and (2) the acoustic actuator (loudspeaker) has significant dynamics. The speaker dynamics can affect performance and stability and must be compensated. While acoustic modal control approaches are typically not sought, there are a number of applications where controlling a few room modes is adequate. A model of a duct with speakers at each end is developed and used to demonstrate the control method, including the impact of the speaker dynamics. An all-pass filter is used to provide phase compensation and improve controller performance and permits the control of nonminimum phase plants. A companion experimental study validated the simulation results and demonstrated nearly 8 dB of control in the first duct mode. A multi-modal control example was also demonstrated producing an average of 3 dB of control in the first four duct modes.
Chaotic Vibration and Internal Resonance Phenomena in Rotor Systems
Authors: Inoue Tsuyoshi , Ishida Yukio
Published: March 2006

Rotating machinery has effects of gyroscopic moments, but most of them are small. Then, many kinds of rotor systems satisfy the relation of 1 to (−1) type internal resonance approximately. In this paper, the dynamic characteristics of nonlinear phenomena, especially chaotic vibration, due to the 1 to (−1) type internal resonance at the major critical speed and twice the major critical speed are investigated. The following are clarified theoretically and experimentally: (a) the Hopf bifurcation and consecutive period doubling bifurcations possible route to chaos occur from harmonic resonance at the major critical speed and from subharmonic resonance at twice the major critical speed, (b) another chaotic vibration from the combination resonance occurs at twice the major critical speed. The results demonstrate that chaotic vibration may occur even in the rotor system with weak nonlinearity when the effect of the gyroscopic moment is small.
Electric-Hydraulic Actuator Design for a Hybrid Squeeze-Film Damper-Mounted Rigid Rotor System With Active Control
Authors: Yau Her-Terng , Chen Chieh-Li
Published: March 2006

When a squeeze-film damper-mounted rigid rotor system is operated eccentrically, the nonlinear forces are no longer radially symmetric and a disordered dynamical behavior (i.e., quasi-periodic and chaotic vibration) will occur. To suppress the undesired vibration characteristics, the hybrid squeeze-film damper bearing consisting of hydrostatic chambers and hydrodynamic ranges is proposed. In order to change the pressure in hydrostatic chambers, two pairs of electric-hydraulic orifices are used in this paper. The dynamic model of the system is established with the consideration of the electric-hydraulic actuator. The complex nonsynchronous vibration of squeeze-film dampers rotor-bearing system is demonstrated to be stabilized by such electric-hydraulic orifices actuators with proportional-plus-derivative (PD) controllers. Numerical results show that the nonchaotic operation range of the system will be increased by tuning the control loop gain.
A Global Control Strategy for Efficient Control of a Braille Impact Hammer
Authors: Jerrelind Jenny , Dankowicz Harry
Published: March 2006

A combined control scheme relying on feedback-based local control in the vicinity of periodic system responses and global control based on a coarse-grained approximation to the nonlinear dynamics is developed to achieve a desirable dynamical behavior of a Braille printer impact hammer. The proposed control methodology introduces discrete changes in the position of a system discontinuity at opportune moments during the hammer motion while the hammer is away from the discontinuity, thereby exploiting the recurrent contacts with the discontinuity to achieve the desired changes in the transient dynamics. It is argued that, as the changes in the position of the discontinuity affect the motion only indirectly through changes in the timing and state at the subsequent contact, the control actuation can be applied over an interval of time during the free-flight motion as long as it is completed prior to contact. A forced, piecewise smooth, single-degree-of-freedom model of a Braille impact hammer is used to illustrate the methodology and to yield representative numerical results.
A Transfer-Matrix-Perturbation Approach to the Dynamics of Chains of Nonlinear Sliding Beams
Authors: Luongo Angelo , Romeo Francesco
Published: March 2006

Chains of nonlinear shear indeformable beams with distributed mass, resting on movable supports, are considered. To determine the dynamic response of the system, the transfer-matrix approach is merged with the harmonic balance method and a perturbation method, thereby transforming the original space-temporal continuous problem into a discrete one-dimensional map xk+1=F(xk) expressed in terms of the state variables xk at the interface between adjacent beams. Such transformation does not imply any discretization, because it is obtained by integrating the single-element field equations. The state variables consist of both first-order variables, namely, transversal displacement and couples, and second-order variables, which are longitudinal displacement and axial forces. Therefore, while the linear problem is monocoupled, the nonlinear one becomes multicoupled. The procedure is applied to determine frequency-response relationship under free and forced vibrations.
Prediction of the Stability Envelope of Rotor-Bearing System
Authors: Wang J. K. , Khonsari M. M.
Published: March 2006

A method is developed for predicting the stability envelope of a rotor-bearing system using the Hopf bifurcation theory. Results are compared to published literature obtained using a trial-and-error method.
Auxiliary Bearing Life Prediction Using Hertzian Contact Bearing
Model
Authors: Sun Guangyoung
Published: March 2006

A rotating machine with active magnetic bearings (AMBs) requires conventional bearings as a backup support system in the case of AMB failure. This paper presents an estimated auxiliary/catcher bearing (CB) L10 fatigue life based on the Hertzian contact dynamic loads between bearing ball and races during the touchdown. The thermal growths of bearing components are predicted using a one-dimensional thermal model, and the resulting expansions contribute to the calculation for the Hertzian contact loads. Numerical simulations for an energy-storage flywheel module reveal that a high-speed backward whirl significantly reduces the CB life and that an optimal damping lowers the CB temperature and increases the CB life.
Damage Identification Using Sensitivity-Enhancing Control and Identified Models
Authors: Solbeck Jason A. , Ray Laura R.
Published: March 2006

This paper investigates a coherence approach for locating structural damage using modal frequencies and transfer function parameters identified from input-output data using Observer/Kalman filter identification (OKID). Autonomous damage identification using such forward methods generally require (i) a structural model by which to relate measured and predicted modal properties induced by damage, and (ii) good sensitivity of modal parameter changes to damage states. Using the coherence approach, a damage parameter vector comprised of a finite set of modal frequencies and transfer function parameters is hypothesized for each damage case using either identified or analytic structural models. Measured parameter vectors are extracted from experimental input-output data for a damaged structure using OKID and are compared to hypotheses to determine the most likely damage state. The richness of the parameter vector set, which is comprised of high-quality frequency measurements and lower-quality transfer function parameters, is evaluated in order to determine the ability to uniquely localize damage. The method is evaluated experimentally using a three-degree-of-freedom torsional system and a space-frame truss. Damage parameter hypotheses are generated from a model of the healthy structure developed by system identification in the torsional system, and an analytic model is used to generate damage hypotheses for the truss structure. Feedback control laws enhance the parameter vectors by including closed-loop modal frequencies in order to reduce noise sensitivity and improve uniqueness of parameter vector hypotheses to each damage case. Results show improvements in damage identification using damage parameter vectors comprised of open- and closed-loop modal frequencies, even when model error exists in structural models used to form damage parameter vector hypotheses.
Concept of Coupled Displacement Field for Large Amplitude Free Vibrations of Shear Flexible Beams
Authors: Rao G. Venkateswara , Saheb K. Meera , Janardhan G. Ranga
Published: March 2006

Continuum solutions for solving the large amplitude free vibration problem of shear flexible beams using the energy method involves assuming suitable admissible functions for the lateral displacement and the total rotation. Use of even, single-term admissible functions leads to two coupled nonlinear temporal differential equations in terms of the lateral displacement and the total rotation, the solution of which is rather involved. This situation can be effectively tackled if one uses the concept of a coupled displacement field wherein the fields for lateral displacement and the total rotation are coupled through the static equilibrium equation of the shear flexible beam. This approach leads to only one undetermined coefficient, in the case of single-term admissible functions, which can easily be used in the principle of conservation of total energy, neglecting damping, to solve the problem. Finally, one gets a nonlinear ordinary differential equation of the Duffing type which can be solved using any available standard method. The effectiveness of the concept discussed above is brought out through the solution of the large amplitude free vibrations, in terms of the fundamental frequency, of uniform shear flexible beams, with axially immovable ends, using single-term admissible functions.