bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of methods to enhance extrinsic tooth discoloration for comparison of toothpastes
Authors: Pontefract H. , Courtney M. , Smith S. , Newcombe R. G. , Addy M.
Published: December 2003

Background: The interaction of chlorhexidine with dietary chromogens to cause extrinsic dental staining has been exploited in vitro and in vivo to study tooth discoloration and its control. These studies in vitro investigated factors that might enhance stain formation, and evaluated formulations to inhibit the stain with the primary aim of devising a protocol for use in vivo.

Method: The standard method cycled acrylic specimens through saliva, 0.2% chlorhexidine and tea on the hour 8 times per day and stain was measured using a spectrophotometer. Test interventions were 3 “whitening” toothpastes (A, P, R), a fluoride toothpaste (C) and water. In studies 1 and 3 interventions were at 09:00 and 16:00, and in studies 2 and 4 at 09:00 and 13:00. Between cycles, specimens remained dry in studies 1 and 2 and were maintained in water day and night in studies 3 and 4. Studies 5–7 determined the influence of tea temperature, exposure time and concentration, and chlorhexidine temperature and exposure time on stain development. Studies 8–10 modified the standard procedure using tea at triple strength and 50°C, and assessed stain inhibition by toothpastes and water using optical density, colorimetric and visual assessment recordings.

Results: In studies 1–4, there were highly significant differences between interventions. Overall, the experimental whitening paste (P) produced the most stain inhibition, and water or the proprietary whitening paste (R), produced the least stain inhibition. More stain inhibition was seen with interventions at 09:00 and 16:00. Both tea concentration and temperature significantly influenced staining. Chlorhexidine temperature did not influence staining. Exposure time to tea and chlorhexidine had a small effect on staining. In studies 8 and 9, interventions at 09:00 and 16:00 were more effective; the most stain inhibition was with paste P and the least with water, paste R being intermediate. In study 10, P was the most effective and R the least effective interventions.

Conclusions: These studies in vitro suggest that the chlorhexidine tea stain model can be manipulated to enhance stain and thereby should improve discrimination between stain inhibition formulations. The timing of interventions in the model appears to be important. These studies in vitro were used to plan a clinical protocol.
The usefulness of using Ramfjord teeth in predicting periodontal status of a Tanzanian adult population
Authors: Mumghamba E. G. S. , Pitiphat W. , Matee M. I. N. , Simon E. , Merchant A. T.
Published: December 2003

Objectives: The only partial mouth index that has been validated against full‐mouth examinations in the East African population is the CPITN (Community Periodontal Index of Treatment Needs). Since the Ramfjord index can potentially shorten the examination time by almost half, we evaluated Ramfjord teeth in predicting full‐mouth periodontal status of an adult population in Tanzania.

Material and Methods: Pocket depth was measured for 192 consecutive patients aged from 15 to 77 years (36 years old on average); 86 (45%) females referred to the Department of Restorative Dentistry, Muhimbili National Hospital, Tanzania between January 1997 and December 1999, and the mean pocket depth for full‐mouth and Ramfjord teeth was calculated.

Results: The correlation between the mean pocket depth calculated from the full‐mouth and Ramfjord teeth was 0.96. The β coefficient for the mean pocket depth measured by Ramfjord teeth to predict the full‐mouth mean was 0.94, and was not affected by adjustment for age, missing teeth or sex.

Conclusion: This overall high agreement between Ramjford teeth and full‐mouth periodontal pocket situation confirms the epidemiological validity of Ramfjord's dental sample in our setting.
Analysis of periodontal risk profiles in adults with or without a history of myocardial infarction
Authors: Renvert Stefan , Ohlsson Ola , Persson Susanna , Lang Niklaus P. , Rutger persson G.
Published: December 2003

Background: An association between periodontitis and cardiovascular diseases has been suggested.

Aims: To study whether a combination of clinical variables in a functional risk diagram enhanced the ability to differentiate between subjects with or without an immediate history of acute myocardial infarction (AMI).

Material and Methods: A functional periodontal pentagon risk diagram (PPRD) with five periodontal risk vectors was created. The surface of individual PPRDs was calculated using data from 88 subjects with recent AMI and 80 matched control subjects with no history of AMI.

Results: Age, gender, number of remaining teeth (mean value: 21.1 versus 21.6 teeth), smoking status, and pocket probing depth (PPD) distribution did not differ by group. Gingival recession was greater in control subjects (mean difference: 5.7, SD: ±1.9, p<0.01, 95% CI: 1.8–9.6). Bone loss 4.0 mm was at all levels studied was significantly greater in subjects with AMI and bone loss 50% (4 mm) was the best individual predictor of AMI (β=2.99, p<0.000, 95% CI: 7.5–53.4). Only PPRD scores were associated with AMI status when factors not included in the PPRD were studied (β=22.1, SE: 5.9, p<0.0001, 95% CI: 10.3–33.7). The best association between AMI status and study variables was the combination of 4 mm of bone loss 50%, proportion of bleeding on probing (%BOP), %PPDs6 mm, and tooth loss (Nagelkirke r2=0.46).

Conclusions: The combination of five periodontal parameters in a PPRD added predictive value, suggesting that comprehensive data should be used in studies of associations between periodontitis and heart diseases. Radiographic evidence of bone loss was the best individual parameter.
Poor oral health is associated with coronary heart disease and elevated systemic inflammatory and haemostatic factors
Authors: Montebugnoli L. , Servidio D. , Miaton R.A. , Prati C. , Tricoci P. , Melloni C.
Published: December 2003

Objectives:

To assess the relationship between poor oral health and coronary heart disease (CHD) and systemic inflammatory and haemostatic factors in an Italian population.

Material and Methods: The study population consisted of 63 males aged 40–65 years with proven CHD and 50 controls matched for age, geographic area, and socioeconomic status. A detailed description of their oral status was given using four different dental indices (total dental index (TDI), panoramic tomography score, clinical periodontal sum score (CPSS), and clinical and radiographic sum score (CRSS)). Blood samples were taken for measurement of the following CHD risk factors: serum total cholesterol, triglycerides, high‐density lipoprotein (HDL) cholesterol, low‐density lipoprotein (LDL) cholesterol, and glucose; a series of systemic markers of inflammation (C‐reactive protein, leucocytes, fibrinogen, homocysteine) and a series of haemostatic factors (von Willebrand factor, fibrin d‐dimer, prothrombinic fragment F1.2, plasminogen activator inhibitor type I (PAI‐1), and serum antibodies) against oxidized LDL (anti‐Ox‐LDL).

Results: Multiple logistic regression adjusted for all risk factors for CHD showed statistically significant relationships (p<0.01) between all dental indices and CHD. Significant relationships (p always <0.01) were found between CPSS and CRSS and leucocyte count. Significant relationships (p always <0.05) were also found between TDI and the von Willebrand factor, and between CPSS and the von Willebrand factor, anti‐Ox‐LDL, and PAI‐1.

Conclusions: The present study suggests an association between poor oral status and CHD, and provides evidence that inflammatory and haemostatic factors could play an important role in this association.
Attachment loss after scaling and root planing with different instruments
Authors: Alves Renato V. , Machion Luciana , Casati Márcio Z. , Nociti Francisco H. , Sallum Antônio W. , Sallum Enilson A.
Published: December 2003

Objectives: The aim of this study was to evaluate clinically the immediate effect of trauma from instrumentation after scaling and root planing with different instruments.

Material and Methods: Ten subjects with moderate chronic periodontitis, presenting probing depths ranging from 3.5 to 6.5 mm on anterior teeth, upper and/or lower, were selected. Teeth were randomly assigned to one of the following groups: MC group – scaled and planed with Gracey mini‐curettes (MiniFiveTM); CC group – scaled and planed with Gracey conventional curettes. The selected teeth were probed with a computerized electronic probe, guided by an occlusal stent, and then subjected to scaling and root planing. Immediately following instrumentation, teeth were probed again. The difference between relative attachment level (RAL) immediately before and after instrumentation was considered as trauma from instrumentation.

Results: Intra‐group analysis revealed statistically significant differences between RAL immediately before and after instrumentation in both groups (0.68±0.32 for MC group; and 0.83±0.41 for CC group –p<0.05). However, inter‐group analysis did not show a statistically significant difference in trauma from instrumentation caused by the different instruments.

Conclusions: Within the limits of this study, it was concluded that root instrumentation causes an average trauma from instrumentation of 0.76 mm with no differences between the tested instruments.
Fate of bone formed by guided tissue regeneration with or without grafting of Bio‐Oss® or Biogran®
Authors: Stavropoulos Andreas , Kostopoulos Lambros , Nyengaard Jens Randel , Karring Thorkild
Published: December 2003

Objectives: The aim of the study was to examine whether bone produced by guided tissue regeneration (GTR) in combination with Bio‐Oss® or Biogran® is stable on a long‐term basis.

Material and Methods: Fifty‐four, 3‐month‐old Wistar rats were divided into three groups and rigid, hemispherical, teflon capsules were placed with their open part facing the lateral surface of the exposed mandibular ramus (one capsule per animal). In the first group, the capsules were loosely packed with a standardized quantity of Bio‐Oss®, in the second group with Biogran®, and in the last group were left empty. After 1 year of healing, the capsules were removed. Six animals from each of the 3 experimental groups were killed immediately after capsule removal (baseline), or 3 or 6 months after re‐entry. The volume of (1) newly formed bone, (2) remaining biomaterial particles, and (3) soft connective tissue in the space originally created by the capsule was estimated by a point‐counting technique in three to four histological sections, taken by uniformly random sampling.

Results: While considerable bone formation had occurred in the empty control capsules, only limited bone formation was observed in the two test groups. The major portion of the space originally created by the capsules in the test groups was occupied by biomaterial particles embedded in connective tissue. At baseline, the mean volume of newly formed bone occupied 23% of the original capsule space in the animals grafted with Bio‐Oss®, 12.6% in those implanted with Biogran®, and 94.1% in those that received empty control capsules. Six months after capsule removal, the corresponding values were 21.5%, 13.2%, and 91.7%, respectively. No statistically significant differences were observed between baseline, and the 3‐, and 6‐month observation times in terms of bone volume for any of the three treatment groups (p>0.05).

Conclusion: Bone produced by GTR with and without implantation of Bio‐Oss®, or Biogran®, is stable on a long‐term basis, but bone formation is obstructed by implantation of these biomaterials.
Polymer‐assisted regeneration therapy with Atrisorb® barriers in human periodontal intrabony defects
Authors: Hou Lein‐Tuan , Yan Ji‐Jong , Tsai Alex Yi.‐Min , Lao Chia.‐Shih , Lin Shih.‐Jung , Liu Cheing‐Meei
Published: December 2003

Aim: This study compared clinical results of 40 periodontal osseous defects treated by two types of absorbable barrier materials.

Material and Methods: Thirty patients (23 males and seven females) suffering from moderate to advanced periodontitis (with comparable osseous defects) were randomly assigned to receive either Atrisorb® barrier (n=22; group A) or Resolut XT® barrier (n=18; group B) therapy. Periodontal phase I treatment and oral hygiene instruction were performed before periodontal surgery. Papillary preservation, partial thickness flap, citric acid root conditioning, and decortication procedures were applied during the operation. Bone defects were filled with demineralized freeze‐dried bone allograft and minocycline mixture (4:1 ratio). Postoperative care included 0.10% chlorhexidine rinse daily and antibiotic medication for 2 weeks. Clinical assessments including probing depth (PD), clinical attachment level (CAL), gingival recession (GR), plaque index (PlI), gingival index (GI), and radiographic examinations were taken at the baseline, preoperatively and at 3 and 6 months after regenerative surgery.

Results: Six months following therapy, both Atrisorb® and Resolut XT® groups had achieved comparable clinical improvement in pocket reduction (3.9 versus 4.4 mm), attachment tissue gain (clinical attachment gain; 3.5 versus 3.6 mm), and reduction in the GI and in the PlI. Within‐group comparisons showed significant attachment gain and pocket reduction between baseline data and those at both 3 and 6 months postoperatively (p<0.01). There were no statistically significant differences in any measured data between groups A and B.

Conclusions: The results of this study indicate that a comparable and favorable regeneration of periodontal defects can be achieved with both Atrisorb® and Resolut XT® barriers. Further long‐term study and histologic observations of tissue healing are needed to evaluate whether Atrisorb® is promising for clinical use.
Enamel matrix proteins in the treatment of intra‐bony defects
Authors: Francetti Luca , Del Fabbro Massimo , Basso Matteo , Testori Tiziano , Weinstein Roberto
Published: December 2003

Background: A growing flow of recent evidence indicates enamel matrix derivative (EMD, Emdogain®) as a useful tool for the regeneration of periodontal tissues. This prospective clinical study aimed to evaluate the efficacy of EMD combined with surgical treatment of periodontal intra‐bony defects, as compared with surgery alone, up to 24 months of follow‐up.

Methods: Twenty‐four intra‐bony defects were treated in 24 patients in a single clinical centre. Each defect had intra‐bony depth (IBD) ≥4 mm and probing pocket depth (PPD) ≥6 mm. Patients were randomly assigned to either test or control group. Plaque index (PI), gingival index (GI), PPD and periodontal attachment level (PAL) were assessed at baseline pre‐surgical examination at the site to be treated. Full mouth plaque score (FMPS) and full mouth bleeding score (FMBS) were also evaluated. Twelve patients were treated by simplified papilla preservation flap technique (control group), while 12 patients were treated with the same surgical technique plus EMD after ethylenediamine tetraacetic acid root conditioning (test group). Any probing at the involved sites was avoided in the first year post‐surgery. Radiographs were taken at baseline, 12 and 24 months after surgery using customized bite blocks. Intra‐bony defect depth (IBD) and angle (IBA) were measured from X‐rays by a computer‐aided technique. At 12 and 24 months post‐surgery, FMPS, FMBS, PI, GI, PPD, PAL and radiographic IBD and IBA were assessed. The difference between each follow‐up and baseline, and between groups at each follow‐up was evaluated for the above parameters by standard statistical methods.

Results: In both groups, clinical and radiographic parameters were improved at either 12 or 24 months when compared with baseline. The test group displayed better outcomes when compared with the control group for IBD, PPD, and PAL gain at 12 months, and only for PAL and IBD gain at 24 months. No adverse event related to the use of EMD was reported.

Conclusions: The surgical procedure used in the present study, aiming for maximum preservation of the regenerative potential of periodontal tissues, showed per se excellent results. The use of EMD as an adjunct to periodontal surgery in the treatment of angular defects possibly enhances periodontal regeneration rate.
A randomized clinical trial on the short‐term clinical and microbiological effects of the adjunctive use of a 0.05% chlorhexidine mouth rinse for patients in supportive periodontal care
Authors: Santos Sagrario , Herrera David , López Elsa , O'Connor Ana , González Itziar , Sanz Mariano
Published: December 2003

Objective: To evaluate the clinical and microbiological activity of a new mouth rinse formulation, used as an adjunct to oral hygiene, for patients in supportive periodontal care.

Patients and Methods: This was a randomized, placebo‐controlled clinical trial with two groups: test group, rinsing twice per day with the test product (with 0.05% chlorhexidine and 0.05% cetylpyridinium chloride); and control group, rinsing with a placebo. Treated chronic periodontitis patients were included, and two visits were rendered, baseline, and after 15 days. Clinical outcome variables included plaque and gingival indices, and probing pocket depth. Subgingival samples were processed by culturing. Patient‐based variables and adverse effects were also assessed. Outcome variables were compared by t‐test, χ2, and Mann–Whitney test.

Results: The results belonged to 33 patients. Plaque and gingival indices, and the log of bacterial total counts were reduced in the test group (p0.01), but differences between groups were only statistically significant (p<0.05) for plaque and bacterial counts. A significant reduction in the proportions of flora (p<0.05) and frequency of detection (p=0.01) of Porphyromonas gingivalis was observed in the test group.

Conclusions: The newly formulated mouth rinse demonstrated short‐term plaque‐inhibitory activity. This was associated with a reduction in the total load of anaerobic subgingival microflora.
Effects of toothbrushing frequency on proliferation of gingival cells and collagen synthesis
Authors: Yamamoto Tatsuo , Tomofuji Takaaki , Ekuni Daisuke , Sakamoto Tomonori , Horiuchi Masazumi , Watanabe Tatsuo
Published: December 2003

Background: Mechanical stimulation by toothbrushing enhances proliferation of fibroblasts and junctional epithelium (JE). These changes in gingiva may depend on the interval between toothbrushing. The effects of toothbrushing frequency on proliferation of gingival fibroblasts and basal cells of JE were evaluated.

Methods: Twelve mongrel dogs were used. Each tooth was brushed for 20 s at 1.96 N. The subepithelial connective tissue of JE was examined for proliferating cell nuclear antigen (PCNA)‐positive fibroblasts and procollagen type‐I C‐peptide (PIP)‐positive fibroblasts. JE was examined for PCNA‐positive basal cells.

Results: Gingiva that received brushing twice a day showed increases in the density of fibroblasts and ratio of PCNA‐positive fibroblasts to total fibroblasts at 4 weeks. The ratio of PIP‐positive fibroblasts increased at 8 weeks in gingiva brushed twice a day and once a day. PCNA‐positive basal cell ratio increased at 4 weeks in gingiva brushed twice a day and once a day.

Conclusions: A high frequency of brushing was associated with increased numbers of PCNA‐positive fibroblasts, PIP‐positive fibroblasts and PCNA‐positive basal cells. Gingival cell proliferation increased and reached a plateau earlier in gingiva brushed twice a day than in gingiva brushed once a day.
Longitudinal monitoring of subgingival colonization by Actinobacillus actinomycetemcomitans, and crevicular alkaline phosphatase and aspartate aminotransferase activities around orthodontically treated teeth
Authors: Perinetti Giuseppe , Paolantonio Michele , Serra Emanuela , D'Archivio Domenico , D'Ercole Simonetta , Festa Felice , Spoto Giuseppe
Published: December 2003

Objectives: During orthodontic treatment, changes in subgingival plaque colonization and tissue inflammation and remodelling have been described. This study uses a longitudinal design to examine subgingival colonization of Actinobacillus actinomycetemcomitans (Aa) and alkaline phosphatase (ALP) and aspartate aminotransferase (AST) activities in gingival crevicular fluid (GCF) in order to assess whether these parameters have potential as biomarkers of tissue responses to orthodontic tooth movement in humans.

Materials & Methods: Twenty‐one patients (ages: 11.2–22.5; mean 17.1±3.3 years) participated in the study. An upper canine from each patient undergoing treatment for distal movement served as the test tooth (DC), and its contralateral (CC) and antagonist (AC) canines were used as controls. The CC was included in the orthodontic appliance, but was not subjected to the orthodontic force; the AC was free from any orthodontic appliance. The subgingival plaque and GCF around the experimental teeth was harvested from both mesial and distal tooth sites immediately before appliance activation and on day 28. Clinical gingival condition was evaluated at the baseline and at the end of the experimental period. Aa colonization was determined by culture methods, while ALP and AST activities were evaluated spectrophotometrically.

Results: Throughout the study, the clinical conditions worsened in both the DCs and the CCs as compared with the baseline, whereas no significant differences were found between the DCs and the CCs, or between mesial and distal sites of each of these teeth on day 28. In the ACs, clinical parameters remained at baseline levels throughout the study. Similar results were found for Aa colonization, which increased significantly on day 28 in the DC and CC groups. On day 28, ALP and AST activities were significantly elevated in all sites from the DC and CC groups as compared with the ACs, where, conversely, enzymatic activities remained at the baseline levels. However, ALP activity in the DC group was significantly greater than in the CCs at mesial (tension) sites on day 28, while AST activity in the DCs was significantly elevated as compared with the CC group at the distal (compression) sites. Greater ALP activity in the DC group was observed at the tension sites compared with the compression sites on day 28.

Conclusions: Our results suggest that Aa subgingival colonization, and ALP and AST activities in GCF reflect the tissue responses that occur in the periodontium during orthodontic treatment.
The Structural Relation Between Mortgage and Market Interest Rates
Authors: Marathe Achla , Shawky Hany A.
Published: December 2003

This paper analyzes the dynamic relationship between primary and secondary mortgage markets and the short‐term and long‐term market interest rates. Using a series of monthly data on fixed rate mortgage rates and GNMA rates, we explore the dependence and speed of adjustment in these primary and secondary mortgage rates to each other as well as to the long and short‐term government rates. The results indicate that residential mortgage rates in general, appear to follow the long‐term rate and are not very sensitive to movements in the short‐term interest rate.
Equity Rights Issues in Spain: Flotation Costs and Wealth Effects
Authors: Martín‐Ugedo Juan F.
Published: December 2003

This paper analyses the flotation costs and the share price reaction of equity offerings in Spain. The results report a positive relationship between relative flotation costs and the underwriting of an issue, and a negative relationship between such costs and ownership concentration. Fixed flotation costs and a negative relationship with the gross offer proceeds are also observed. On average, there is a negative share price reaction on the date of the ‘previous communication’ to the Comisión Nacional del Mercado de Valores. The different sub‐samples analysed according to the underwriting of the issue and the discount offered reveal no statistical differences.
Endogenous Parameter Time Series Estimation of the Ohlson Model: Linear and Nonlinear Analyses
Authors: Morel Mindy
Published: December 2003

This paper tests the empirical validity of the Ohlson (1995) model on a firm‐level time series basis. The coefficients of the earnings dynamic and valuation equations are first estimated by OLS. Next, recognizing the nonlinear relationships among the parameters, each equation is estimated by nonlinear Least Squares. Lastly, the model is estimated as a restricted system by nonlinear Least Squares and nonlinear SUR. In all cases, parameters are endogenously estimated. Irrespective of the estimation method, the Ohlson model often yields inconsistent or insignificant parameter estimates. Nevertheless, point estimates of equity risk premia are similar to those obtained from alternative methodologies.
Monitoring the Behaviour of Credit Card Holders with Graphical Chain Models
Authors: Stanghellini Elena
Published: December 2003

Consumer credit has become an enormous business in industrialized countries. Recently, finance agencies have started to develop new products aiming not only to widen their portfolio but also to keep active relationships with good clients already taken on file and to prevent bad clients from becoming a loss for the agency. As a result, models for the whole behaviour of the clients are necessary. They involve many related outcome variables, which altogether give a measure of whether the client revealed to be profitable or unprofitable. This paper aims to show the potential of graphical chain models in the described context.
Assessing the Economic Significance of Return Predictability: A Research Note
Authors: Boudry Walter , Gray Philip
Published: December 2003

The predictability of stock returns is often assessed using classical statistical significance from predictive regressions. Statistical inference, however, can belie the economic importance with which investors regard various predictors. This paper examines the influence that predictors have on an investor's optimal portfolio allocations. The results show that return predictability is sufficient to induce horizon effects in optimal allocations. After incorporating estimation risk, however, little evidence of predictability remains. We also assess the relative importance of three predictor variables. While dividend yield is the most important predictor, optimal allocations are also sensitive to the term spread and the relative bill rate.
Voluntary Disclosure of Nonproprietary Information: A Complete Equilibrium Characterization
Authors: Korn Evelyn , Schiller Ulf
Published: December 2003

The so‐called disclosure principle is a ‘puzzle’ in the accounting literature: Game theoretic models of financial markets show that in equilibrium firms should disclose all their private information. Yet, the result is not convincing. Researchers have therefore built sophisticated models in order to demonstrate for which reasons the disclosure principle might fail. This note shows that even in the original model there are multiple equilibria. In those equilibria good types disclose and bad types do not. The commonly known full disclosure equilibrium is a limit point of the equilibrium set.
Efficiency, Ownership and Market Structure, Corporate Control and Governance in the Turkish Banking Industry
Authors: Isik Ihsan , Hassan M. Kabir
Published: December 2003

Turkish banks are quite heterogeneous in terms of organizational form, ownership structure, size, age, portfolio concentration, growth prospects and attitude toward risk. They also exhibit strong variations in performance as measured by several efficiency indices. In the light of theoretical advances in corporate finance and financial institutions, this paper is an in‐depth cross‐sectional analysis of the Turkish banking sector, which explores the various bank, market and regulatory characteristics that may explain the efficiency variations across banks. Consistent with the related hypotheses investigated, the results indicate that a number of independent bank characteristics are significantly correlated with various efficiency measures.
Dividend Policy, Corporate Governance and the Managerial Entrenchment Hypothesis: An Empirical Analysis
Authors: Farinha Jorge
Published: December 2003

This paper analyses the agency explanation for the cross‐sectional variation of corporate dividend policy in the UK by looking at the managerial entrenchment hypothesis drawn from the agency literature. Consistent with predictions, a significant U‐shaped relationship between dividend payout ratios and insider ownership is observed for a large (exceeding 600 firms) sample of UK companies and two distinct periods. These results strongly suggest the possibility of managerial entrenchment when insider ownership reaches a threshold of around 30%. Evidence is also presented that non‐beneficial holdings by insiders can lead to entrenchment in conjunction with shares held beneficially.
Age‐related variation in wing shape of migratory and sedentary Blackcaps Sylvia atricapilla
Authors: Pérez‐Tris Javier , Tellería José Luis
Published: December 2003

In many passerines, juveniles have shorter and more rounded wings than adults. Given that (1) long and pointed wings improve endurance in migratory flights, (2) shorter and rounded wings improve manoeuvrability, and (3) juvenile birds are more vulnerable to predators than adults, it has been hypothesised that ontogenetic variation in wing shape results from a greater importance of predation avoidance relative to migration performance during the first year of life. If so, wing shape should not change with age in the absence of migration‐related selection for longer and more pointed wings. We test this by studying the variation with respect to age in wing length and wing pointedness of migratory and sedentary Blackcaps wintering in southern Spain. Migratory Blackcaps had longer and more pointed wings than sedentary Blackcaps. Juveniles had shorter wings than adults in migratory populations, but not in sedentary populations. The variation with age in wing pointedness was less pronounced, and was found in migratory females only. These differences between the two traits could be related to a stronger selection for pointed wings than for longer wings with increasing distance of migration, and to an increased migratoriness of females in partially migratory Blackcap populations. We hypothesise that, in migratory Blackcaps, a shorter and more rounded wing in juveniles could be selected for if the decrease in predation rate compensated for the somewhat greater costs of the first migration attempt. On the other hand, there are no costs of migration in sedentary Blackcaps, which hence maintain a similar wing shape, giving high manoeuvrability, both as juveniles and as adults.
Eucalyptus pollen grain emptying by two Australian nectarivorous psittacines
Authors: Gartrell B. D. , Jones S. M.
Published: December 2003

The relative importance of pollen as a source of protein to vertebrates is controversial. In nectarivorous psittacine birds, field studies support its importance, but an experimental study in a nectarivorous parrot showed that less than 7% of pollen grains were emptied. We investigated pollen grain emptying by two nectarivorous Australian parrots, the Swift Parrot Lathamus discolor and the Musk Lorikeet Glossopsitta concinna. We used a controlled experiment, and examined pollen located at different levels through the alimentary tract of wild L. discolor. There was significant emptying of pollen grains (x=45.4%±1.91 s.e.) by all birds in the experimental trials. There was also a progressive increase in the percentage of pollen grains emptied at different sites along the alimentary tract in wild birds (crop x=24.2%±4.44 s.e., proventriculus x=34.0%±7.29 s.e., duodenum x=54.3%±5.42 s.e. and distal intestine x=64.2%±4.68 s.e.). The percentage of pollen grains emptied by captive L. discolor in the experimental trial (x=44.1%±2.77 s.e.) was not significantly different from that found in wild L. discolor (x=40.3%±4.25 s.e.). Both species of nectarivorous parrot were able to rapidly ingest large quantities of Eucalyptus pollen and appeared to empty the pollen grains efficiently. Eucalyptus pollen appears to be an important source of protein for these birds.
Yolk steroids and the development of the hatching muscle in nestling European Starlings
Authors: Lipar Joseph L.
Published: December 2003

Hatching asynchrony in avian species often leads to the establishment of a size hierarchy among nestlings. Because the youngest nestlings in a brood are often at a significant disadvantage with respect to competition for parentally‐delivered food, one might expect to find that mechanisms have evolved to alleviate the detrimental effects of hatching asynchrony and enhance the survival of last‐hatched offspring. The musculus complexus, or hatching muscle, is responsible for breaking the shell during hatching and for dorsal flexion and extension of the neck during begging. An increase in its strength in last‐hatched nestlings could therefore reduce the duration of hatching or enhance the ability to beg for parentally‐delivered food, thereby enhancing the competitive abilities of those nestlings. I previously found in the Red‐winged Blackbird Agelaius phoeniceus that the mass of the complexus increases with laying order and that its development is mediated by the actions of yolk testosterone. I investigated the hypothesis that yolk steroids also affect the development of the complexus in the European Starling Sturnus vulgaris. I asked, first, whether the mass of the complexus increases with laying order and, if so, whether this increase is at least partially attributable to a corresponding increase in the concentration of yolk testosterone. Because exogenous progesterone increases the water content of the complexus in the domestic fowl Gallus gallus I also asked whether an increase in complexus mass, if present, could be partially attributable to an increase in progesterone concentration across the laying order. I found that both yolk testosterone concentration and the mass of the complexus increased with laying order; however, there was no variation in the concentration of either yolk progesterone or the proportion of water in the complexus across the laying order. There were no differences in the concentrations of either androstenedione or 5α‐dihydrotestosterone across the laying order.
In vivo magnetic resonance imaging of the reproductive organs in a passerine bird species
Authors: Czisch M. , Coppack T. , Berthold P. , Auer D.P.
Published: December 2003

For researchers working on the reproductive anatomy of birds, the standard tool has been the scalpel. We demonstrate that magnetic resonance imaging (MRI) allows us to study non‐invasively the testes and ovaries of small birds. Thus, repeated measurements of the same individual can be obtained at different life‐history stages or before and after experimental treatment with a minimum of harm done to the birds. We present cross‐sectional images of male and female Garden Warblers Sylvia borin at different stages of their gonadal maturation cycle to illustrate the high resolution that can be achieved through MRI. Volumetric analyses enabled us to determine the total testicular volume with high accuracy.
High ectoparasite loads in hole‐nesting birds – a nestbox bias?
Authors: Wesołowski Tomasz , Stańska Marzena
Published: December 2003

All studies of interactions between fleas and hole‐nesting birds so far have been done in nestboxes. This study, which is the first study of flea infestation of nests of hole‐nesters in natural holes, was carried out in the Białowieża National Park (E Poland) and demonstrated that, in contrast to those studies, both prevalence (below 10%) and intensity of infestation nests of Parus palustris and Ficedula flycatchers were very low, an order of magnitude lower than elsewhere. However, in the same forest, flycatchers breeding in nestboxes, and tits in natural holes within the nestbox plot, had significantly higher infestation rates, approaching those found in other studies. These observations indicate that the high flea loads reported for tits and flycatchers may be a product of biased sampling – exclusive collection of data in nestbox areas – rather than reflect their species‐specific characteristics. The data from natural holes undermine the widespread assumption that data on flea loads in nestboxes can be treated as representative, and generalised to areas without nestboxes.
Restoration of body mass in King Penguins after egg abandonment at a critical energy depletion stage: early vs late breeders
Authors: Robin Jean‐Patrice , Fayolle Christine , Decrock Frédéric , Thil Marie‐Anne , Côté Steeve D. , Bernard Servane , Groscolas René
Published: December 2003

In fasting‐incubating seabirds, it has been proposed that egg abandonment and refeeding should be induced when a low body mass (BM) threshold is attained, thus ensuring adult survival at the expense of immediate breeding. In the context of life‐history trade‐offs in long‐lived birds, we have tested this hypothesis by comparing short‐term survival and restoration of BM in King Penguins Aptenodytes patagonicus that abandoned their egg to those that were relieved normally by their mate at the end of the first incubation shift. Since King Penguins have an extended laying period, the possible influence of seasonal factors was also examined by comparing early and late breeders. Forty incubating males were experimentally forced to fast until egg abandonment by preventing relief by the female. At egg abandonment of both early and late breeding males, BM was below the BM threshold, fasting duration was eight days (about 30%) longer than for relieved birds, and plasma uric acid level was elevated (signature of increased body protein catabolism, phase III of fasting). All abandoning birds survived and came back from sea at a BM similar to that of relieved penguins. The duration of the foraging trip of abandoning early breeders was the same as that of relieved birds, and some abandoning birds engaged in a new breeding attempt. Abandoning late breeders, however, made foraging trips twice as long as those of relieved males. This difference can be explained by time constraints rather than nutritional constraints, abandoning early breeders having enough time left in the breeding season to engage in a new breeding attempt in contrast to abandoning late breeders. These observations lend support to the suggestion that not only BM but also an internal clock intervene in the decision to engage in breeding or not. By preventing a lethal energy depletion ashore and by acting at a fasting stage where the capacity to restore BM at sea is unaffected, abandonment at a low body condition threshold plays a major role in the trade‐off between adult penguin survival and reproduction.
Coal Tit fat‐storing patterns during the non‐breeding season: the role of residence status
Authors: Broggi Juli , Brotons Lluís
Published: December 2003

According to the optimal body mass hypothesis, resident individuals, having priority of resource access and better knowledge of food availability in an area, should carry smaller fat reserves than transients whose resource predictability is lower. We tested this prediction in a free‐living population of Coal Tits Parus ater in sub‐alpine coniferous forest during three winters. We examined the role of residence status in determining the daily patterns of fat accumulation of individuals using time of day, temperature, season, year and body size as covariates. Only time of day, residence status and temperature significantly affected daily variation of fat score in Coal Tits. Fat scores were higher in transients than residents, although within residents, juveniles did not carry significantly more fat than adults. Our results show that fattening strategies are associated with residence status in the Coal Tit, in support of the hypothesis that transient individuals facing lower food predictability carry larger body fat reserves. The finding that within residents, patterns of fat accumulation did not differ between adults and juveniles, suggests that residence per se, involving higher food predictability, rather than age‐related dominance or hoarding behaviour, determines fattening strategies in wild Coal Tits.
Does diet in Celtic Sea fishes reflect prey availability?
Authors: Pinnegar J. K. , Trenkel V. M. , Tidd A. N. , Dawson W. A. , Du buit M. H.
Published: December 2003

Feeding preferences of Celtic Sea fishes were investigated using a database of stomach content records, collected between 1977 and 1994. The diet of cod Gadus morhua, hake Merluccius merluccius, megrim Lepidorhombus whiffiagonis, whiting Merlangius merlangus and saithe Pollachius virens changed markedly as the animals grew larger, and although large predators generally chose larger bodied prey, the variability of prey sizes consumed also increased. Large predators continued to select small, low value, benthic prey (e.g. Callionymus spp. and Trisopterus spp.) which were easier to catch, rather than larger, more energy lucrative pelagic prey (e.g. mackerel Scomber scombrus), even though these pelagic prey‐fishes were nearly always available and were often very abundant. Stock estimates of the International Council for the Exploration of the Sea and U.K. groundfish survey catches were used as indices of prey abundance. Blue‐whiting Micromesistius poutassou and other small pelagic fishes (Argentina spp. and clupeoids) were identified as being particularly important, and were consumed by some predators more often than would be expected given the abundance of these prey in the environment. There was no evidence for density‐dependent feeding by predators on mackerel and only hake exhibited density‐dependent feeding on horse‐mackerel. Hake, cod and megrim consumed more blue‐whiting when this prey was at higher abundance in the environment. In choosing what prey to consume, predators must balance costs and benefits, considering the quality of prey and the energy expended during search, capture and handling.
Toothless predators: feeding performance and techniques among the piscivores within Lake Tana's endemic barbus species flock (Pisces:Cyprinidae)
Authors: De Graaf M. , Sibbing F. A. , Osse J. W. M.
Published: December 2003

With more than 2000 fish species the Cyprinidae is the largest family of vertebrates. Lake Tana, a large lake (3050 km2) situated in the NW‐ highlands of Ethiopia, harbours, as far as we know the only remaining intact species flock of large (max. 100 cm FL) cyprinid fishes (15 Barbus spp.). One of the most intriguing aspects of this endemic Barbus species flock is the large number of piscivores (8). Cyprinid fishes seem not well designed for piscivory, they lack teeth in the oral jaw, have a small slit‐shaped pharyngeal cavity and all lack a stomach with low pH for digesting large prey. Many barbs are benthivorous species, like the ancestral barb in Lake Tana's isolated system. Why then is piscivory, which is rare among cyprinids, so common in Lake Tana Barbus? The aim of present study was to compare the performance and techniques of these piscivorous Barbus with known piscivores from other fish families. We studied prey handling times over prey size, prey capture using high‐speed movies, and assessed the effect of prey size on performance and prey selection in the field. Performances were explained by functional morphology of their feeding system. Overall, Lake Tana's piscivorous Barbus perform relatively ‘poor’, compared to piscivores from other fish families. For example, Lake Tana's piscivores are only able to handle prey fish smaller than 16% of their own body length. However, Lake Tana lacks potential piscivorous competitors, rendering the piscivorous Barbus by far the ‘best’ and apparently highly successful. They have adapted to all available macro‐habitats (littoral, offshore pelagic and offshore benthic), using different techniques (ambush, pursuit and cruising), a unique scenario for barbs.
Individual‐based models of cod movement and population dynamics
Authors: Edwards H. J.
Published: December 2003

Many fish species undergo seasonal changes in distribution, as a result of horizontal migrations between feeding, nursery and spawning grounds. Exploring the processes involved in these movements may be the key to understanding interactions with other species, man and the environment, and is therefore crucial to effective fisheries management. Recent tagging experiments providing information on the distribution of migratory fish stocks have indicated pronounced regional and temporal differences in the migratory behaviour of cod, suggesting complex interactions between this commercially important fish species and the environment.

This paper presents a model of the horizontal movements of demersal fish, principally cod, using an individual‐based modelling approach to explore and predict the relationship between demersal fish movements and key environmental and ecological factors. The model simulates the basic biological processes of growth, movement and mortality, and is driven by the analysis of physical tagging data recorded by electronic data storage tags (DSTs). Results show that the incorporation of behavioural data from DSTs into spatially explicit individual‐based models can provide realistic simulations of large‐scale fish stocks, thus giving a better understanding of their basic ecology and allowing more effective management of commercially important fish species. Possibilities of future improvements and extensions to the model are discussed.
Sex‐biased dispersal in a salmonid fish: implications for growth rate and survival
Authors: Hutchings J. A.
Published: December 2003

I tested the hypothesis that dispersal is sex‐biased in an unexploited population of brook trout (Salvelinus fontinalis Mitchill). Based on the assumptions that trout are promiscuous and that reproductive success is limited primarily by either number of mates (males) or fecundity (females), I predicted that males would disperse greater distances than females. I also tested the hypothesis that trout populations comprise stationary and mobile individuals, predicting that males have greater mobility than females. Based on a 5‐year, mark‐recapture study of almost 1000 fish, there was strong support for the hypothesis of male‐biased dispersal. On average, males dispersed 2·5 times as far as females; during the spawning period only, male dispersal exceeded that by females almost four‐fold. Both sexes were heterogeneous with respect to movement, with a lower incidence of mobility among females than males. Sex differences in dispersal may have been responsible for sex biases in seasonal growth. Importantly, growth rate was positively associated with survival, independent of the effects of body size. Sex‐biased dispersal may (1) reduce mate competition among male kin, (2) decrease the probability that males will reproduce with related females, and (3) have important implications for life history.
Atlantic salmon change the expression of odorant receptor genes to learn the smell of home
Authors: Jordan W. C. , Dukes J. P. , Deaville R. , Bruford M. W. , Youngson A. F.
Published: December 2003

The ability of salmon to home to their natal stream to spawn has long intrigued biologists. It is known that olfaction is crucial to accurate homing, and that the transition between freshwater and marine environments (the parr‐smolt transformation; PST) is a period of increased olfactory sensitivity and learning, resulting in a permanent memory of natal site odours that is retained in peripheral sensory neurons. These odours are then used as cues by sexually maturing fish on their homeward migration. We have used molecular techniques to demonstrate transient increases in expression of odourant receptor transcripts coincident with PST. Both olfactory and vomeronasal receptors are involved, which suggests that the fish learn both environmental odours and semiochemicals (pheromones). Receptor expression varies between families and changes over time indicating both genetic differences in odour stimuli and multiple periods of olfactory sensitivity. We hypothesise that changes in gene expression may have a role in maintaining population structure in Atlantic salmon.