bluuebunny/crossref_metadata_2025 huggingface dataset:
Global factor trade with differentiated factor prices and factor intensities
Authors: Kwok Yun‐kwong
Published: August 2006

Abstract Relaxing the assumption of internationally identical factor intensity techniques in the HOV model creates two challenges. First, computing actual factor intensity techniques of different countries requires detailed input‐output tables and factor usage data, which are not always available. Second, determinants of the factor intensity technique differences across countries need to be identified. This paper explores the role of relative factor price differences in the determination of factor intensity technique differences across countries and proposes an inferring method that infers factor intensity techniques of different countries based on relative factor price differences. The HOV model is then modified accordingly.
Endogenous trading bloc formation in a North‐South global economy
Authors: Das Satya P. , Ghosh Subhadip
Published: August 2006

Abstract The majority of the trading blocs to date are between similar countries, rather than between developed and developing countries. This paper provides a rationale for why trading blocs among similar countries may arise as an equilibrium phenomenon. It develops a model of an asymmetric world economy in which there are at least four countries. The countries are differentiated with respect to their market size and they choose their trading partners. In the coalition‐proof Nash equilibrium, either there is global free trade or free trade areas are formed among similar countries.
North‐South and South‐South trade‐related technology diffusion: an industry‐level analysis of direct and indirect effects
Authors: Schiff Maurice , Wang Yanling
Published: August 2006

Abstract This paper examines one direct and three indirect channels of North‐South trade‐related technology diffusion. We find that i) the largest impact on TFP in the South is from direct North‐South technology diffusion; ii) there are also significant effects from indirect North‐South technology diffusion, though their magnitude is smaller than that of the direct one; and iii) the impact of direct North‐South technology diffusion on TFP in the South occurs faster than the impact of indirect technology diffusion.
Evolving discretionary practices of U.S. antidumping activity
Authors: Blonigen Bruce A.
Published: August 2006

Abstract Using data on U.S. dumping margin calculations by the U.S. Department of Commerce (USDOC), we first document the rapid rise in U.S. dumping margins from around 15% in the early 1980s to over 60% by 2000. Second, statistical analysis finds that USDOC discretionary practices have played the major role in rising U.S. dumping margins over this period. Importantly, the evolving effect of discretionary practices is due not only to increasing use of these practices over time, but to apparent changes in implementation of these practices that mean a higher increase in the dumping margin whenever they are applied.
Licensing a new product with non‐linear contracts
Authors: Erutku Can , Richelle Yves
Published: August 2006

Abstract This paper looks at a situation where a licensor owns a patent on a technology that allows the production of a new good. The licensor seeks to license its innovation to a set of producers that differ according to their marginal cost of producing an existing good. We show that the licensor is able to obtain the profit a monopolist would achieve by producing the new good. The equilibrium licensing contract specifies both a fixed fee and a royalty scheme based on the production of a licensee.
Informational externalities with lump‐sum sampling
Authors: Haritchabalet Carole , Renault Régis
Published: August 2006

Abstract We consider a game of strategic experimentation where agents are restricted to an all‐or‐nothing sampling strategy. The strategic interaction between agents due to informational externalities is affected by the sizes of the experimentation samples and the sensitivity of information to changes in sample sizes. There is experimentation only if the overall sample is large enough. Equilibrium may involve optimal, insufficient or excessive experimentation relative to a second‐best welfare benchmark. This unusual over‐experimentation result is associated not necessarily with large samples but with a low elasticity of the value of information with respect to the sample size.
The public and private provision of pure public goods and the distortionary effects of income taxation: a political economy approach
Authors: Itaya Jun‐ichi , Schweinberger A.G.
Published: August 2006

Abstract A pure public good is provided by the government and the voluntary contributions of two types of households. The government finances its contribution by means of income taxation. The latter has distortionary effects. A third type of household never makes contributions. We analyse the effects of changes in the income tax rate on (a) the provision of the public good, (b) the private contributions of the households, and (c) changes in the distribution of income and welfare between contributing and non‐contributing households. We derive a simple and testable condition under which the lowering of the income tax entails a Pareto improvement.
Household Finance
Authors: CAMPBELL JOHN Y.
Published: August 2006

The study of household finance is challenging because household behavior is difficult to measure, and households face constraints not captured by textbook models. Evidence on participation, diversification, and mortgage refinancing suggests that many households invest effectively, but a minority make significant mistakes. This minority appears to be poorer and less well educated than the majority of more successful investors. There is some evidence that households understand their own limitations and avoid financial strategies for which they feel unqualified. Some financial products involve a cross‐subsidy from naive to sophisticated households, and this can inhibit welfare‐improving financial innovation.
Market Reactions to Tangible and Intangible Information
Authors: DANIEL KENT , TITMAN SHERIDAN
Published: August 2006

The book‐to‐market effect is often interpreted as evidence of high expected returns on stocks of “distressed” firms with poor past performance. We dispute this interpretation. We find that while a stock's future return is unrelated to the firm's past accounting‐based performance, it is strongly negatively related to the “intangible” return, the component of its past return that is orthogonal to the firm's past performance. Indeed, the book‐to‐market ratio forecasts returns because it is a good proxy for the intangible return. Also, a composite equity issuance measure, which is related to intangible returns, independently forecasts returns.
How Persistent Is the Impact of Market Timing on Capital Structure?
Authors: ALTI AYDOĞAN
Published: August 2006

This paper examines the capital structure implications of market timing. I isolate timing attempts in a single major financing event, the initial public offering, by identifying market timers as firms that go public in hot issue markets. I find that hot‐market IPO firms issue substantially more equity, and lower their leverage ratios by more, than cold‐market firms do. However, immediately after going public, hot‐market firms increase their leverage ratios by issuing more debt and less equity relative to cold‐market firms. At the end of the second year following the IPO, the impact of market timing on leverage completely vanishes.
Can Managers Successfully Time the Maturity Structure of Their Debt Issues?
Authors: BUTLER ALEXANDER W. , GRULLON GUSTAVO , WESTON JAMES P.
Published: August 2006

This paper provides a rational explanation for the apparent ability of managers to successfully time the maturity of their debt issues. We show that a structural break in excess bond returns during the early 1980s generates a spurious correlation between the fraction of long‐term debt in total debt issues and future excess bond returns. Contrary to Baker, Taliaferro, and Wurgler (2006), we show that the presence of structural breaks can lead to nonsense regressions, whether or not there is any small sample bias. Tests using firm‐level data further confirm that managers are unable to time the debt market successfully.
CEOs' Outside Employment Opportunities and the Lack of Relative Performance Evaluation in Compensation Contracts
Authors: RAJGOPAL SHIVARAM , SHEVLIN TERRY , ZAMORA VALENTINA
Published: August 2006

Although agency theory suggests that firms should index executive compensation to remove market‐wide effects (i.e., RPE), there is little evidence to support this theory. Oyer (2004, Journal of Finance 59, 1619–1649) posits that an absence of RPE is optimal if the CEO's reservation wages from outside employment opportunities vary with the economy's fortunes. We directly test and find support for Oyer's (2004) theory. We argue that the CEO's outside opportunities depend on his talent, as proxied by the CEO's financial press visibility and his firm's industry‐adjusted ROA. Our results are robust to alternate explanations such as managerial skimming, oligopoly, and asymmetric benchmarking.
Information Control, Career Concerns, and Corporate Governance
Authors: SONG FENGHUA , THAKOR ANJAN V.
Published: August 2006

We examine corporate governance effectiveness when the CEO generates project ideas and the board of directors screens these ideas for approval. However, the precision of the board's screening information is controlled by the CEO. Moreover, both the CEO and the board have career concerns that interact. The board's career concerns cause it to distort its investment recommendation procyclically, whereas the CEO's career concerns cause her to sometimes reduce the precision of the board's information. Moreover, the CEO sometimes prefers a less able board, and this happens only during economic upturns, suggesting that corporate governance will be weaker during economic upturns.
Do Banks Affect the Level and Composition of Industrial Volatility?
Authors: LARRAIN BORJA
Published: August 2006

In theory, better access to bank credit can reduce or increase output volatility depending on whether firms are more financially constrained during contractions or expansions. This paper finds that the volatility of industrial output is lower in countries with more bank credit. Most of the reduction in volatility is idiosyncratic, which follows from the ability of banks to pool and diversify shocks. Systematic volatility is reduced less strongly. Volatility dampening is achieved via countercyclical borrowing: At the firm level, short‐term borrowing is less (or more negatively) correlated with sales and inventories in countries with high levels of bank credit.
Corporate Financial Policy and the Value of Cash
Authors: FAULKENDER MICHAEL , WANG RONG
Published: August 2006

We examine the cross‐sectional variation in the marginal value of corporate cash holdings that arises from differences in corporate financial policy. We begin by providing semi‐quantitative predictions for the value of an extra dollar of cash depending upon the likely use of that dollar, and derive a set of intuitive hypotheses to test empirically. By examining the variation in excess stock returns over the fiscal year, we find that the marginal value of cash declines with larger cash holdings, higher leverage, better access to capital markets, and as firms choose greater cash distribution via dividends rather than repurchases.
Does Corporate Headquarters Location Matter for Stock Returns?
Authors: PIRINSKY CHRISTO , WANG QINGHAI
Published: August 2006

We document strong comovement in the stock returns of firms headquartered in the same geographic area. Moreover, stocks of companies that change their headquarters location experience a decrease in their comovement with stocks from the old location and an increase in their comovement with stocks from the new location. The local comovement of stock returns is not explained by economic fundamentals and is stronger for smaller firms with more individual investors and in regions with less financially sophisticated residents. We argue that price formation in equity markets has a significant geographic component linked to the trading patterns of local residents.
The Disposition Effect and Underreaction to News
Authors: FRAZZINI ANDREA
Published: August 2006

This paper tests whether the “disposition effect,” that is the tendency of investors to ride losses and realize gains, induces “underreaction” to news, leading to return predictability. I use data on mutual fund holdings to construct a new measure of reference purchasing prices for individual stocks, and I show that post‐announcement price drift is most severe whenever capital gains and the news event have the same sign. The magnitude of the drift depends on the capital gains (losses) experienced by the stock holders on the event date. An event‐driven strategy based on this effect yields monthly alphas of over 200 basis points.
Medical Management of Atrial Fibrillation: State of the Art
Authors: CAMM JOHN
Published: August 2006

Predominantly a disease of advancing age, atrial fibrillation (AF) is the most common sustained arrhythmia. Its prevalence is rising as the proportion of elderly people in the population continues its inexorable rise. Without more effective therapeutic interventions, AF‐related cardiovascular and cerebrovascular morbidity and mortality will also continue to rise. Antiarrhythmic drugs are an essential tool in the management of AF and may be used as premedication before cardioversion; together with cardioversion to help or assist cardioversion; or given afterward to prevent recurrence. If AF recurs after one or two cardioversions, then it is usual to adopt a rate control strategy; highly symptomatic patients who fail cardioversion may benefit from ablation therapy. We are already on the threshold of a large expansion in the use of ablation therapy, a strategy that has potential to deliver dramatic improvements in outcome. Not only can AF be cured by ablative therapy, but there is also evidence that it confers functional improvement as well. It will not, however, be appropriate for all AF patients and pharmacological therapies will continue to have an important place in the management of AF. The plethora of antiarrhythmic drugs currently available for the treatment of AF is a reflection that none is wholly satisfactory, each having limited efficacy combined with poor safety and tolerability. Improved class III antiarrhythmic agents, such as dronedarone; new classes of antiarrhythmic agents, such as atrial repolarization delaying agents; and upstream therapies dealing with substrate represent potential sources of new pharmacological therapies for AF.
The Future of Atrial Fibrillation Therapy
Authors: DORIAN PAUL
Published: August 2006

Today management of atrial fibrillation (AF) centers on restoration and maintenance of normal sinus rhythm or control of the ventricular rate response to AF. Current guidelines state that rhythm and rate control strategies should be considered therapeutically equivalent, but recognize that no “one size fits all,” an approach consistent with growing recognition of the heterogeneity of AF. As data from the Sotalol Amiodarone Atrial Fibrillation Efficacy Trial clearly demonstrate, conventional antiarrhythmics have a role in highly symptomatic AF accompanied by decreased quality of life. However, for many AF patients such drugs lack efficacy, have potentially serious side effects, and are poorly tolerated. In parallel with the development of more effective and safer antiarrhythmics, nontraditional approaches to prevention and treatment of AF are being explored. Treatments not considered “antiarrhythmic” that may prevent or forestall AF include aggressive antihypertensive therapy with angiotensin‐converting enzyme inhibitors or angiotensin receptor blockers, and some, but not all, beta‐blockers and calcium channel antagonists, especially when used as adjunctive therapy. Other approaches include statins, steroids, and fish oil to reduce atrial fibrosis and inflammation, and pacemakers to prevent bradycardia‐mediated AF and as a pacing preventive strategy in selected patients. Ablative techniques with potential to cure AF are gaining popularity, but are not yet simple, straightforward, and risk‐free procedures. In the future, treatment of AF will progress beyond today's focus on AF as a purely electrocardiographic disease toward a patient and context‐specific management strategy involving multiple treatment modalities.
Dronedarone: An Emerging Agent with Rhythm‐ and Rate‐Controlling Effects
Authors: WEGENER FLORIAN T. , EHRLICH JOACHIM R. , HOHNLOSER STEFAN H.
Published: August 2006

Of current antiarrhythmic agents, amiodarone is among the most effective with the additional advantage of having little proarrhythmic potential. However, it can cause potentially serious extracardiac side effects, stimulating the search for safer derivatives. Dronedarone, a new antiarrhythmic drug that is structurally related to amiodarone, lacks an iodine moiety and, thus, amiodarone's iodine‐related organ toxicity, while its methane sulfonyl group decreases lipophilicity so shortening half‐life and decreasing tissue accumulation. Electrophysiological studies show that dronedarone shares amiodarone's multichannel blocking effects, inhibiting transmembrane Na+, K+, Ca2+, and slow L‐type calcium channels, as well as its antiadrenergic effects. Unlike amiodarone, it has little effect at thyroid receptors. Possessing both rate‐ and rhythm‐control properties, dronedarone has proved safe and effective in preventing recurrence of atrial fibrillation (AF) in patients with persistent AF in the Dronedarone Atrial Fibrillation Study After Electrical Cardioversion (DAFNE) trial, the first prospective randomized trial to evaluate its efficacy and safety. Dronedarone has since undergone further extensive evaluation in three pivotal phase III trials. In two sister studies, the European Trial in Atrial Fibrillation or Flutter Patients Receiving Dronedarone for the Maintenance of Sinus Rhythm (EURIDIS) and American–Australian–African Trial with Dronedarone in Atrial Fibrillation/Flutter Patients for the Maintenance of Sinus Rhythm (ADONIS), dronedarone 400 mg b.i.d. showed significant efficacy against placebo in prevention of AF recurrence. Additionally, in patients with permanent AF, dronedarone was highly effective at controlling ventricular rate on top of standard rate‐controlling therapies in the Efficacy and Safety of Dronedarone for the Control of Ventricular Rate during Atrial Fibrillation (ERATO) study.
Optical coherence tomography versus automated perimetry for follow‐up of optic neuritis
Authors: Noval Susana , Contreras Inés , Rebolleda Gema , Muñoz‐Negrete Francisco J.
Published: August 2006

Purpose:  To evaluate the usefulness of optical coherence tomography (OCT) for follow‐up of optic neuritis (ON) compared with subjective visual function tests.

Methods:  Twelve patients with ON underwent a complete ophthalmological evaluation at initial diagnosis, including best corrected visual acuity (VA), visual fields testing and OCT examination. These examinations were repeated periodically over 6 months. Retinal nerve fibre layer (RNFL) thickness evolution was analysed and correlated with VA and visual field mean deviation.

Results:  Six months after ON, mean RNFL in the affected eye decreased significantly compared with that in the fellow eye (24.54%). A significant correlation was found between RNFL thinning and final VA (r = 0.807, p = 0.005), with a 1‐line drop in VA for every 5.4‐µm decrease. All patients with an altered visual field had an abnormal RNFL value; of the seven patients with normal visual fields, 57% had an abnormal RNFL value (p < 5%).

Conclusions:  Optical coherence tomography can detect axonal damage as early as the third month after an isolated initial episode of ON, even in the presence of normal visual fields. Mean RNFL thinning is correlated with final VA.
Use of amniotic membrane as an adjuvant in refractory glaucoma
Authors: Drolsum Liv , Willoch Christian , Nicolaissen Bjørn
Published: August 2006

Purpose:  To evaluate the results after amnion‐shielded trabeculectomy with concomitant use of mitomycin C.

Methods:  The study comprised patients with severely refractory glaucomas who had previously undergone two or more regular trabeculectomies with mitomycin C and, in one case, cyclodestructive cryotherapy. The patients were admitted for surgery between May 2003 and May 2004. Trabeculectomy was performed through a limbus‐based incision in nine eyes of nine patients. Cryopreserved human amniotic membranes obtained from our biobank were impregnated with 0.4 mg/ml mitomycin C and washed for 2 mins in balanced salt solution. One membrane was sutured to the scleral surface and partly positioned under the scleral flap, and another was secured to subconjunctival tissue.

Results:  The mean preoperative intraocular pressure (IOP) was 32.2 mmHg (range 22–44 mmHg). After a follow‐up of 6–18 months (mean 9.8 months), the mean IOP was 16.4 mmHg (range 11–26 mmHg). The mean number of glaucoma medications was reduced from 2.4 preoperatively to 1.4 postoperatively. There were no devastating complications.

Conclusions:  Amnion‐shielded trabeculectomy is a procedure that should be evaluated as an option in refractory glaucoma.
Retinal pigment epithelium changes after photodynamic therapy for choroidal neovascularization in pathological myopia
Authors: Battaglia Parodi Maurizio , Da Pozzo Stefano , Ravalico Giuseppe
Published: August 2006

Purpose:  To describe changes in the retinal pigment epithelium (RPE) induced by photodynamic therapy (PDT) in eyes with subfoveal choroidal neovascularization (CNV) associated with pathological myopia (PM).

Methods:  We carried out an open‐label, prospective, interventional case series including 26 patients affected by subfoveal CNV in PM who underwent PDT with a 12‐month follow‐up. Particular attention was paid to the detection of changes at the RPE level in the areas exposed to the laser compared with baseline conditions.

Results:  The median age of the patients was 58.5 years and the median duration of symptoms was 2 weeks. A pigmentary zone was present before PDT in 20 eyes (77%), incompletely encircling the CNV in all but two of the 20 eyes. At the end of the follow‐up, the CNV in all eyes was seen to be completely or incompletely encircled by a band of hyperpigmentation, which was surrounded by RPE alterations, including depigmentation in all cases and atrophic changes in 14 eyes.

Conclusions:  After PDT, alterations in the RPE develop in myopic eyes. These include accentuation of the pigmentary zone surrounding the CNV and progressive atrophic changes. Further studies are needed to correlate post‐PDT RPE damage with longterm visual outcome.
Fcγ receptor polymorphisms and periodontal status: a prospective follow‐up study
Authors: Wolf D. L. , Neiderud A. M. , Hinckley K. , Dahlén G. , Van De Winkel J. G. J. , Papapanou P. N.
Published: August 2006

Aims: The aims of this study were to assess: (i) the distribution of Fcγ receptor polymorphisms among patients with chronic periodontitis (“cases”) and control subjects with no/minimal loss of periodontal tissue support in a Caucasian population; (ii) whether these polymorphisms can serve as severity markers for periodontitis; and (iii) whether they have any bearing on the response to periodontal therapy.

Methods: The study sample consisted of 132 cases and 73 controls of comparable age and gender. Full‐mouth periodontal status was assessed. Subgingival plaque (PL) samples and blood samples were obtained and analysed with respect to 19 bacterial species and homologous serum immunoglobulin G titres. Polymorphisms in the Fcγ receptor IIa (131R/H) and IIIb (NA1/NA2) were assessed by polymerase chain reaction. Patients underwent periodontal therapy and were followed up at 4 and 30 months.

Results: Neither polymorphism showed a skewed distribution among cases and controls. At baseline, periodontitis patients with Fcγ RIIa‐H/H131 genotype had more PL and deeper pockets than patients in other genotype groups (p<0.05). Both bacterial levels and antibody titres were unrelated to genotype. The longitudinal analysis failed to detect an association between genotype and response to periodontal therapy.

Conclusions: The present data failed to demonstrate a clinically relevant relationship between the Fcγ receptor IIa (131R/H) or IIIb (NA1/NA2) polymorphism and periodontal status.
Pre‐term delivery and periodontal disease: a case–control study from Croatia
Authors: Bošnjak Andrija , Relja Tomislav , Vučićević‐Boras Vanja , Plasaj Hrvoje , Plančak Darije
Published: August 2006

Aim: The aim of this report was to assess the strength and influence of periodontitis as a possible risk factor for pre‐term birth (PTB) in a cohort of 81 primiparous Croatian mothers aged 18–39 years.

Methods: PTB cases (n=17; mean age 25±2.9 years; age range 20–33 years) were defined as spontaneous delivery after less than 37 completed weeks of gestation that were followed by spontaneous labour or spontaneous rupture of membranes. Controls (full‐time births) were normal births at or after 37 weeks of gestation (n=64; mean age 25±2.9 years; age range 19–39 years). Information on known risk factors and obstetric factors included the current pregnancy history, maternal age at delivery, pre‐natal care, nutritional status, tobacco use, alcohol use, genitourinary infections, vaginosis, gestational age, and birth weight. Full‐mouth periodontal examination was performed on all mothers within 2 days of delivery.

Results: PTB cases had significantly worse periodontal status than controls (p=0.008). Multivariate logistic regression model, after controlling for other risk factors, demonstrated that periodontal disease is a significant independent risk factor for PTB, with an adjusted odds ratio of 8.13 for the PTB group (95% confidence interval 2.73–45.9).

Conclusion: Periodontal disease represents a strong, independent, and clinically significant risk factor for PTB in the studied cohort. There are strong indicators that periodontal therapy should form a part of preventive prenatal care in Croatia.
Estrogen and alendronate therapies may prevent the influence of estrogen deficiency on the tooth‐supporting alveolar bone: a histometric study in rats
Authors: Duarte P. M. , Gonçalves P. , Casati M. Z. , De Toledo S. , Sallum E. A. , Nociti F. H.
Published: August 2006

Background and Objective:  The aim of this study was to evaluate histometrically the influence of estrogen deficiency, and its therapies, on the quality of the tooth‐supporting alveolar bone.

Material and Methods:  Seventy‐three female rats were randomly assigned to one of the following groups: group 1 (n = 15), sham surgery; group 2 (n = 15), bilateral ovariectomy (OVX); group 3 (n = 14), OVX plus calcitonin (16 IU/kg); group 4 (n = 14), OVX plus estrogen (20 µg/kg); and group 5 (n = 15), OVX plus alendronate (5 mg/kg). Eighty days after surgery, the animals were killed and their mandibles were removed and processed for histology. Bone density (BD) in the furcation area of the first mandibular molar (i.e. the percentage of demineralized bone tissue in a 1,000 µm zone under the furcation) was histometrically obtained.

Results:  Data analysis demonstrated that estrogen deficiency negatively affected the tooth‐supporting bone density (79.45% ± 4.22 and 55.23% ± 6.45, for groups 1 and 2, respectively), and that estradiol and alendronate therapies prevented this effect (61.67% ± 6.87, 78.09% ± 3.12 and 81.47% ± 4.58, for groups 3, 4 and 5, respectively).

Conclusion:  Within the limits of this study, it can be concluded that the density of tooth‐supporting bone is affected by estrogen deficiency, and that estradiol and alendronate therapies, but not calcitonin, provide protection against this effect.
Location of putative stem cells in human periodontal ligament
Authors: Chen S. C. , Marino V. , Gronthos S. , Bartold P. M.
Published: August 2006

Background and Objective:  The origin of cells in the mature periodontium, and the location of their progenitors, are still unknown. It is also unknown whether inflammation influences the number and distribution of these cells within the periodontium. Molecules such as STRO‐1, CD146 and CD44 have been identified on a variety of mesenchymal stem cells. The aim of this study was to identify and localize putative stem cells in diseased and healthy human periodontal ligament using cell‐surface markers for mesenchymal stem cells.

Material and Methods:  Healthy and periodontitis‐affected teeth were collected, fixed in 10% neutral‐buffered formalin, decalcified and embedded in paraffin in preparation for immunohistochemistry. Antibodies against STRO‐1, CD146 and CD44 were used to identify putative stem cells in the periodontal ligament.

Results:  Putative stem cells were identified in both healthy and diseased periodontal ligament. They were mainly located in the paravascular region and small clusters of cells were also found in the extravascular region. Wider distributions of these cells were detected in sections of diseased ligament.

Conclusion:  Within the periodontal ligament of both healthy and diseased teeth, cells have been identified consistent with their identification as putative stem cells. The presence of an inflammatory reaction associated with periodontitis may enhance the number of these cells.
Cytokine production in human periodontal ligament cells stimulated with Porphyromonas gingivalis
Authors: Yamamoto T. , Kita M. , Oseko F. , Nakamura T. , Imanishi J. , Kanamura N.
Published: August 2006

Background and Objective:  Although some functions and characterizations of human periodontal ligament (hPDL) cells have been reported, the role of hPDL cells in periodontal disease is poorly understood. We have previously reported that hPDL cells produce many kinds of inflammatory cytokines by stimulation with Prevotella intermedia. In this study, we examined the production of cytokines in hPDL cells stimulated with Porphyromonas gingivalis as compared with P. intermedia.

Material and Methods:  hPDL cells cultured in Dulbecco's modified Eagles's medium (DMEM) containing 10% fetal bovine serum (FBS) and antibiotics. After three to four passages, hPDL cells were stimulated with P. intermedia (ATCC25601) or P. gingivalis (ATCC33277) for 24 h. Total RNA was extracted by ISOGEN and the expression of cytokine mRNA was determined using reverse transcription–polymerase chain reaction. Cytokines in the culture supernatants were assessed by enzyme‐linked immunosorbent assay.

Results:  The expression of interleukin‐1β, interleukin‐6, interleukin‐8, tumor necrosis factor‐α (TNF‐α), receptor activator of nuclear factor‐κB ligand (RANKL) and osteoprotegerin (OPG) mRNA was detected in hPDL cells after stimulation with P. gingivalis as well as P. intermedia. There were no significant differences in the kind of cytokines expressed in hPDL cells between P. gingivalis and P. intermedia. However, P. gingivalis induced a significantly higher production of cytokines in hPDL cells than P. intermedia (p < 0.05).

Conclusion:  This study demonstrated that hPDL cells produce many kinds of cytokines as a result of bacterial stimulation, including stimulation with P. gingivalis and P. intermedia. These results suggest that hPDL cells may play a role in cytokine production in periodontal disease.
Incidence of Noncarious Cervical Lesions and Their Relation to the Presence of Wear Facets
Authors: Telles Daniel , Pegoraro Luiz Fernando , Pereira José carlos
Published: August 2006

Problem:  Noncarious cervical lesions are characterized by loss of tooth structure in the cervical area, compromising its integrity and resulting in esthetic problems for the patient.

Purpose:  The purpose of this study was to assess noncarious cervical lesions in young patients in an attempt to establish a possible relationship to the presence of wear facets.

Materials and Methods:  First‐year dental students of Bauru Dental School were studied to verify the prevalence of noncarious cervical lesions and their relationship to the presence of wear facets. After 3 years, the students were examined again to verify the incidence of new lesions, trying to establish a correlation to the previous existence of wear facets.

Results:  Of the 1,131 teeth analyzed, 129 had noncarious cervical lesions. Twenty‐nine of the 40 students had at least one tooth with one lesion. After 3 years, the incidence of new lesions was 57. Mandibular first molars (22.3%), mandibular first premolars (13.2%), mandibular second premolars (13.2%), and maxillary first molars (12.4%) showed the highest prevalence of lesions. On final analysis, 86.8% of all teeth presenting lesions showed wear facets. The identification of new lesions associated with the presence of wear facets identified during the first exam 3 years earlier was statistically significant (p < 0.01).

Conclusions:  The patterns of wear facets found in the study population examined were associated with an increased occurrence of noncarious cervical lesions.

CLINICAL SIGNIFICANCE

Occlusal factors, especially the presence of wear facets, should be considered in the management of noncarious cervical lesions.
Correlation between Facial Measurements and the Mesiodistal Width of the Maxillary Anterior Teeth
Authors: Gomes Vanderlei Luiz , Gonçalves Luiz Carlos , Do Prado Célio jesus , Junior Itamar Lopes , De Lima Lucas Bárbara
Published: August 2006

One of the most difficult aspects during the selection of maxillary anterior teeth for a removable prosthesis is determining the appropriate mesiodistal width of the six maxillary anterior teeth. Many attempts have been made to establish methods of estimating the combined width of these anterior teeth, and improving the esthetic outcome. The proportion of facial structures and the relationship between facial measurements and natural teeth could be used as a guide in selecting denture teeth. The aim of this study was to verify the relation between the combined mesiodistal width of the six maxillary anterior teeth and the facial segments: the width of the eyes, the inner canthal distance (ICD), the interpupillary distance (IPD), the interalar width, and the intercommissural width (ICm). Standardized digital images of 81 dentate Brazilian subjects were used to measure both facial and oral segments when viewed from the frontal aspect through an image processing program. To measure the distance between the upper canines on a curve, accurate casts were made from the upper right first premolar to the upper left first premolar. The Spearman rank correlation coefficient was conducted to measure the strength of the associations between the variables (α =0.05). The results showed a significant correlation between all facial elements and the combined mesiodistal width of the six teeth, when observed from the frontal aspect. The ICD, IPD, and ICm showed the highest probability of being correlated to the mesiodistal width of the teeth (p=0.000).

CLINICAL SIGNIFICANCE

This article considers facial analysis with digital photography as a practical and efficient application to select the mesiodistal width of artificial anterior teeth in an esthetically pleasing and natural appearance during an oral rehabilitation treatment.
Remineralization Potential of a Fluoridated Carbamide Peroxide Whitening Gel
Authors: Gladwell Jason , Simmons Darrin , Wright J. timothy
Published: August 2006

Purpose:  Little knowledge exists regarding the potential remineralizing benefits of adding fluoride to carbamide peroxide‐based whitening gels. The aim of this project was to evaluate whether a whitening system with fluoride will remineralize previously demineralized enamel.

Materials and Methods:  Twenty‐four extracted teeth were sectioned into quadrants labeled A to D. Tooth quadrants in groups A, B, and D were demineralized with a lactic acid, methyl‐cellulose gel system to mimic incipient carious lesions. Group C was neither demineralized nor treated. Group D was demineralized, but not treated with a whitening gel. Groups A and B were exposed to one of two commercially prepared 10% carbamide peroxide whitening gels: one that was fluo‐ride free (group A) and one that contained fluoride (0.463%NaF) (group B). Remineralization was evaluated histologically and analyzed statistically using paired t tests accepting p < 0.05 as significant.

Results:  Shade comparisons showed equal whitening efficacy of both gel A and B. Paired t tests show a significant reduction in lesion depth after treatment with the fluoride containing gel (B: mean lesion depth=100 μm; p < 0.01), while there was no difference for the gel lacking fluoride (A: mean lesion depth=110 μm).

Conclusion:  Under the conditions of this study, the addition of fluoride to a tooth whitening system does not affect the gel’s whitening efficacy. The addition of fluoride could provide remineralization properties to the gel. As tooth whitening therapies continue to grow and evolve, a strong focus should rest on improving these materials in ways that will provide ever greater patient benefits. Coupling the esthetic benefits of whitening with the preventive benefits of fluoride is a natural step in this direction.

CLINICAL SIGNIFICANCE

Therapuetic quantities of fluoride can impact remineralization properties of commercially available tooth whitening gels without altering whitening properties.
Accuracy of LED and Halogen Radiometers Using Different Light Sources
Authors: Roberts Howard W. , Vandewalle Kraig S. , Berzins David W. , Charlton David G.
Published: August 2006

Purpose:  To determine the accuracy of commercially available, handheld light‐emitting diode (LED) and halogen‐based radiometers using LED and quartz‐tungsten‐halogen (QTH) curing lights with light guides of various diameters.

Methods:  The irradiance of an LED curing light (L.E.Demetron 1, SDS/Kerr, Orange, CA, USA) and a QTH curing light (Optilux 501, SDS/Kerr) were measured using multiple units of an LED (Demetron L.E.D. Radiometer, SDS/Kerr) and a halogen radiometer (Demetron 100, SDS/Kerr) and compared with each other and to a laboratory‐grade power meter (control). Measurements were made using five light guides with distal light guide diameters of 4, 7, 8, 10, and 12.5 mm. For each light guide, five readings were made with each of three radiometers of each radiometer type. Data were analyzed with two‐way analysis of variance/Tukey; α=0.05.

Results:  In general, both handheld radiometer types exhibited significantly different irradiance readings compared with the control meter. Additionally, readings between radiometer types were found to differ slightly, but were correlated. In general, the LED radiometer provided slightly lower irradiance readings than the halogen radiometer, irrespective of light source. With both types of handheld radiometers, the use of the larger‐diameter light guides tended to overestimate the irradiance values as seen in the control, while smaller‐diameter light guides tended to underestimate.

CLINICAL SIGNIFICANCE

The evaluated LED or halogen handheld radiometers may be used interchangeably to determine the irradiance of both LED and QTH visible‐light‐curing units. Measured differences between the two radiometer types were small and probably not clinically significant. However, the diameter of light guides may affect the accuracy of the radiometers, with larger‐diameter light guides overestimating and smaller‐diameter guides underestimating the irradiance value measured by the control instrument.
AT‐HOME BLEACHING: PULPAL EFFECTS AND TOOTH SENSITIVITY ISSUES, PART I
Authors: Swift Edward J.
Published: August 2006

The most common side effect of at‐home bleaching is transient tooth sensitivity. Despite its high frequency, this phenomenon is not well understood. This two‐part Critical Appraisal presents a summary and analysis of several articles on tooth sensitivity issues with at‐home bleaching. The first installment reviews articles that focus on the incidence of sensitivity, long‐term effects of bleaching, and related pulpal concerns. The second installment also will cover pulpal concerns, as well as the prevention of sensitivity during at‐home whitening treatments.
Inclusion of novel bacteria in rumen microbiology: Need for basic and applied science
Authors: KOBAYASHI Yasuo
Published: August 2006

Rumen microbiology has made a significant contribution to the understanding of ruminant nutrition. However, further progress in research has been hindered by the incomplete analysis of the rumen microbiota comprised of bacteria, protozoa and fungi, most of which remain uncharacterized due to the difficulties in their isolation and cultivation. In order to maximize rumen fiber digestion, it is necessary to understand the community structure of rumen microbes, especially bacteria, and the factors that influence their composition. Recent advances in molecular biology techniques allow the analysis of such bacteria without cultivation, thereby identifying many functional, but uncultured, bacteria as new targets for basic and applied research. Specific uncultured bacterial groups are being considered as important members of a fibrolytic consortium in the rumen, judging by their ecologic distribution. The inclusion of such uncharacterized bacteria in analyses is crucial for understanding the rumen microbial community and its manipulation. In addition, these bacteria could potentially be candidates as probiotics and sources of enzymes for animal feed and other industrial uses.
Social behavior in laboratory rats: Applications for psycho‐neuroethology studies
Authors: YAMAMURO Yutaka
Published: August 2006

The social behavior in laboratory animals occurs in conspecific groups. In the past two decades, the physiological basis of the social behavior in laboratory rats has been gradually elucidated through various neural approaches. In addition, the relevance of social related behavior for psycho‐neuroethology studies has been extensively proposed. An analysis of social recognition behavior of new conspecifics is a useful approach for the study of memory without aversive alternatives such as fear, pain and anxiety. Furthermore, it is considered that artificial or experimental social isolation can induce altered emotional states in laboratory rats. This article reviews the past findings regarding social behavior and aspects of its expression, and discusses further possibilities for animal models of human neuro‐psychiatric disorders.
Effect of restricted feeding on metabolic adaptations of Kamphaengsaen and crossbred Brahman heifers
Authors: KLINHOM Phongchai , MARKVICHITR Kanchana , VIJCHULATA Pravee , TUMWASORN Sornthep , BUNCHASAK Chaiyapoom , CHOOTHESA Apassara
Published: August 2006

Metabolic adaptation during feed deprivation was determined in five Kamphaengsaen (KPS) and six crossbred Brahman (Crossbred Bra) heifers. All heifers were fed at the rate of 85% of the metabolizable energy requirement for maintenance. At the end of 20 days of restricted feeding, the Crossbred Bra heifers lost more bodyweight than the KPS heifers (12.0 vs. 7.2 kg) (P < 0.05). In both groups of heifers there was a similar depletion of back‐fat thickness, however, the loin eye area of the Crossbred Bra heifers decreased more than KPS heifers (8.43 vs. 0.92%; P < 0.05). Feed restriction elevated the rate of lipolysis in adipose tissue, resulting in increased nonesterified fatty acids concentrations in plasma. The Crossbred Bra heifers had a greater serum high density lipoprotein triacylglycerol concentration than the KPS heifers (17.02 vs. 9.53 mg/dL; P < 0.05). This would suggest that the hepatic tissues in the Crossbred Bra heifers exported more triacylglycerols as very low density lipoprotein than in the KPS heifers. During the feed restriction period, the plasma β‐hydroxybutyrate concentration for the heifers was elevated; however, Crossbred Bra heifers shown less plasma β‐hydroxybutyrate concentration than KPS heifers (242 vs. 326 µmol/L; P < 0.05). This may be due to the difference in very low density lipoprotein secretion between the two groups of heifers. There were significant differences in plasma urea‐nitrogen and plasma glucose concentrations (P < 0.05), with the KPS heifers showing less extensive plasma urea‐nitrogen concentration and hypoglycemia, whereas the Crossbred Bra heifers had more extensive plasma urea‐nitrogen concentration and euglycemia. These two metabolites were suggestive of a ketogenic effect on muscle protein catabolism. In conclusion, it was found that the underfed KPS heifers utilized ketone bodies as their energy source, thus limiting body protein degradation, whereas the Crossbred Bra adapted to feed deprivation by exhibiting an auto‐regulation mechanism for ketogenesis and broke down body protein extensively to satisfy their demand for glucose.
Increase of ruminal fiber digestion by cellobiose and a twin strain of Saccharomyces cerevisiae live cells in vitro
Authors: LILA Zeenat Ara , MOHAMMED Nazimuddin , TAKAHASHI Tsuyoshi , TABATA Masahiko , YASUI Takashi , KURIHARA Mitsunori , KANDA Shuhei , ITABASHI Hisao
Published: August 2006

This experiment was designed to investigate the effects of different concentrations of cellobiose (CB) or a twin strain of Saccharomyces cerevisiae live cells (YST) (20, 40 and 60 mg/60 mL), and CB + YST (60 + 20, 60 + 40, 60 + 60 mg/60 mL) on mixed ruminal microorganism fermentation in vitro. Ruminal fluid was collected from a cow, mixed with phosphate buffer (1:2) and incubated (60 mL) anaerobically at 38°C for 24 h with or without supplement plus 400 mg (dry matter [DM] basis) substrate (hay plus concentrate, 1.5:1). The medium pH numerically decreased with CB and CB + YST, but was unchanged with YST. The total volatile fatty acid and proportion of propionate increased (P < 0.05) in all cases. The proportion of acetate decreased (P < 0.05) with CB and CB + YST, but increased (P < 0.05) with YST and that of butyrate increased (P < 0.05) with CB and CB + YST, but decreased (P < 0.05) with YST. Ammonia‐N decreased (P < 0.05) with CB and CB + YST, but was unchanged with YST. The number of protozoa was unchanged, and that of cellulolytic bacteria increased (P < 0.05) in all cases. Total gas production increased (P < 0.05) in all cases. Methane decreased, hydrogen was unchanged by YST and both gases were unchanged by CB and CB + YST. The in vitro disappearance of DM and neutral detergent fiber increased (P < 0.05) by 11.2% and 8.9%, 9% and 8.5%, and 12.1% and 10.2% in the case of CB, YST and CB + YST, respectively. Therefore, the dietary supplementation of CB and/or YST may improve ruminal fermentation and digestibility.
Ileal amino‐acid digestibility of wheat, autoclaved wheat and spaghetti by‐products for broiler chicks
Authors: ZAGHARI Mojtaba
Published: August 2006

An experiment was conducted to determine true and apparent ileal amino‐acid digestibility of a native cultivar of wheat (Mahdavi), autoclaved wheat (120°C for 30 min) and spaghetti by‐products available in Iran. One hundred 21‐day‐old broiler chickens were fed a standard corn–soybean meal starter diet from day 0 to 28 post hatch. At 28 days 80 chicks were distributed according to possessing very nearly the same average bodyweight to 20 wire cages. The experimental units were allocated at random to five dietary treatments with four replicates per treatment. The basal diet contained corn and soybean meal as the major ingredients. Three test diets were formulated containing wheat, autoclaved wheat and spaghetti by‐products as the sole source of dietary protein and each test diet was combined with a basal diet 50:50 on a weight basis to form three assay diets. The apparent and true digestibility of amino acid in the test ingredients were estimated from those in the assay diets basal/test diet mixtures, using the difference method. The apparent and true amino‐acid digestibility of the test ingredients were significantly different (P < 0.01). Autoclaving of wheat increase its amino‐acid digestibility (P < 0.01). Among the test ingredients, the average ileal amino‐acid digestibility of spaghetti by‐products was higher than wheat and autoclaved wheat but it was lower than values for the basal diet (P < 0.01).