bluuebunny/crossref_metadata_2025 huggingface dataset:
Measuring The Effect Of Casino-Operated Restaurant Volume On Slot Machine Business Volume: An Exploratory Study
Authors: Lucas Anthony F. , Santos Jocelina
Published: March 2006

Using data from three different North American casino markets, models designed to explain the variance in slot machine business volume (coin-in) produced a significant and positive effect for a variable representing casino-operated restaurant business volume (covers). Simultaneous multiple regression analysis was used to test the audited, secondary data for significance at the .05 alpha level. A 200-day period was examined for each casino property. The results of this study contradicted an earlier, counterintuitive finding by Lucas and Brewer that provided the basis for this work. The related literature is scarce, largely anecdotal, and split regarding the nature of the relationship between restaurants’ and casinos’ volumes. This exploratory study adds valuable empirical results to this limited but growing literature base while highlighting important strategic and managerial implications.
A Brand Loyalty Model Involving Cognitive, Affective, and Conative Brand Loyalty and Customer Satisfaction
Authors: Back Ki-Joon , Parks Sara C.
Published: March 2006

Despite the amount of research focusing on brand loyalty, empirical tests of the relationship between customer satisfaction and brand loyalty have not been conducted. The primary purpose of this study was to investigate the mediating effects of attitudinal brand loyalty on the relationship between customer satisfaction and behavioral brand loyalty. More over, we developed a robust brand loyalty measurement in the lodging industry by using attitudinal and behavioral brand loyalty constructs. The majority of respondents were business travelers who stayed at an upper-middle-class business hotel. The results of this investigation suggested that customer satisfaction had a significant indirect effect on behavioral brand loyalty when mediated by attitudinal brand loyalty, including cognitive-affective-conative brand loyalty stages. Thus, practitioners should consider customers'perceptions of their brand and not rely solely on purchasing frequencies when measuring brand loyalty levels.
Mature Motorcoach Travelers' Satisfaction: A Preliminary Step toward Measurement Development
Authors: Hsu Cathy H. C.
Published: March 2006

A measurement with 55 tour provider and tour package attributes designed to assess mature travelers' motorcoach tour satisfaction was tested. Data were collected from 817 travelers aged 55 and older. A six-dimension solution consisted of 20 items were derived from the exploratory factor analysis using data from 408 randomly selected respondents. The structure equation modeling, using the other 409 cases, confirmed the six dimensions— goodness-of-fit indices concluded that the data fit the proposed model. The convergent validity of the measurement was also established by examining individual parameters from the measurement and structural equation models. Three of the six latent variables (i.e., flexible schedule, tour guide, and price and value) were found to have significant effect on travelers' overall satisfaction. Although results indicating the measurement as satisfactory, suggestions for instrument revision are provided to enhance its reliability and increase the total variability explained in future studies. Practical implications for tour operators are also provided.
Relationships between Hotel Room Pricing, Occupancy, and Guest Satisfaction: A Longitudinal Case of a Midscale Hotel in the United States
Authors: Mattila Anna S. , O'Neill John W.
Published: March 2006

This case study examined the relationship among hotel room prices, occupancy percentage, and guest satisfaction using 3 years of data from 3,875 actual guest satisfaction surveys at an upper-midscale hotel. The study concludes that price was a significant predictor of overall guest satisfaction and three key guest-satisfaction components: guest room cleanliness, maintenance, and attentiveness of staff (with negative, curvilinear relationships in all cases). Conversely, occupancy percentage failed to be a significant predictor of guest satisfaction.
Consumer Frustration in the Customer-Server Exchange: The Role of Attitudes Toward Complaining and Information Inadequacy Related to Service Failures
Authors: Susskind Alex M.
Published: March 2006

Based on the customer-server exchange, this investigation examines the phenomenon of consumer frustration. Specifically, this investigation examines consumers' perceptions of frustration as it relates to service failure in service-based transactions. The results indicate that consumers'(a) propensity to complain was related to their perceptions of receiving adequate information in the customer-server exchange regarding service failures, (b) negative attitudes toward complaining was not significantly related to information inadequacy or perceptions of consumer frustration, and (c) perceptions of information inadequacy were significantly related to perceptions of consumer frustration in the customer-server exchange.
Travelers’ Prior Knowledge and its Impact on their Information Search Behavior
Authors: Gursoy Dogan , McCleary Ken W.
Published: March 2006

The purpose of this study was to examine the influence of prior knowledge on travelers’information search behavior. This study examined prior knowledge as having two dimensions: familiarity and expertise. The influence of familiarity and expertise on information search was examined utilizing a structural equation modeling approach. The results of this study provide support for multidimensional prior knowledge. The results also indicate that expertise is a function of familiarity and both familiarity and expertise affect travelers’information search behavior. However, the magnitude and direction of the effects of travelers’familiarity on their information search behavior are different from the effects of their expertise. Findings suggest that although the effect of familiarity on internal search is positive and on external search is negative, the effect of expertise on internal search is negative and on external search is positive.
Hotel Branding Strategy: Its Relationship to Guest Satisfaction and Room Revenue
Authors: O’Neill John W. , Mattila Anna S.
Published: March 2006

U.S. hotel brands and international hotel brands headquartered in the United States have increasingly evolved away from being hotel operating companies to being brand management and franchise administration organizations. This trend has allowed for the accelerated growth and development of many major hotel brands and the increasing growth of franchised hotels. There are numerous strategic implications related to this trend. This study seeks to analyze some of these strategic implications by evaluating longitudinal data regarding the performance of major hotel brands in the marketplace, both in terms of guest satisfaction and revenue indicators. Specifically, the authors test whether guest satisfaction at variousU.S. and international brands influences both brand occupancy percentage and average daily room rate 3 years later. In addition, the authors investigate whether the percentage of franchised hotel properties influences both guest satisfaction and occupancy 3 years later. Also, they test whether overall brand size has a positive or detrimental effect on future hotel occupancy. Finally, whether the change in guest satisfaction for hotel brands effects the change in average daily rate during the same 3-year period is tested.
Multi-Stage Synthetic Hotel Pricing
Authors: Kim Woo Gon , Han Jinsoo , Hyun Kyungsuk
Published: March 2006

This study presents a multi-stage synthetic model designed to aid hotel room pricing. The complicated factors used in this model include fixed and variable costs, profit goal, identification of market competition, factors needed to measure a differentiation price premium, price standard limits, and factors needed to develop discriminatory pricing for different segments of customers. The model framework can provide realistic perspectives of hotel room rates. A five-star international hotel was used to illustrate the application of this model by deriving actual price data. A critical step in this model was to develop the hotel's market premium price (MPP) based on consumer surveys. Factor analysis, ANOVA, and the Scheffé post-hoc tests were utilized in the analysis. The model provides new insights into hotel room pricing by offering a step-by-step process leading to room-pricing decisions for hotel revenue managers and marketers.
Noninvariant Measurement Versus Traditional Approaches for Studying Cultural Differences: A Case of Service Expectations
Authors: Cheung Gordon W. , Murrmann Kent F. , Murrmann Susanne K. , Becker Cherylynn
Published: March 2006

Current cross-cultural comparisons in hospitality and tourism research are largely based on differences in simple average scores. This method assumes equal weights for the items and hence fails to address cross-cultural differences in the relative importance of each attribute in comprising the overall evaluation. In this study, a comparison between United States customers and Hong Kong customers in restaurant service expectations is used to demonstrate that latent variable scores are more appropriate than simple average scores for cross-cultural comparisons. The two samples demonstrate differences in relative importance for some items measuring restaurant service expectations. By calculating the latent variable score both with and without factorial invariance, researchers can decompose cross-cultural differences into a component due to item responses, and a second component due to unequal item-construct relationships. It is demonstrated that meaningful cross-cultural comparisons are possible only when noninvariant items are carefully examined.
Exploring the Korean Wine Market
Authors: Lee Kyuho , Zhao Jinlin , Ko Jae-Youn
Published: March 2006

This exploratory study identified specific preferences and characteristics of Korean wine consumers. Relevant literature was reviewed in an attempt to find the most suitable market strategy in the Korean wine market. This study employed samples from members of a Korean wine association (KISA) to identify Korean wine consumers' characteristics and preferences. The study found Korean wine consumers had interesting preferences and that there were some significant differences between these preferences and demographic characteristics among the Korean respondents. The paper offers wine marketers suggestions about what they need to understand in order to attract Korean wine consumers and what may be appropriate and effective wine-marketing strategies and practices in Korea.
Exploring Students’ Evaluations of Teaching Effectiveness: What Factors are Important?
Authors: Gursoy Dogan , Umbreit W. Terry
Published: March 2006

This study investigated the dimensions of students'evaluations of teaching effectiveness in a school of hospitality business management and examined the interrelations among these dimensions. A rigorous process of statistical testing utilizing exploratory and confirmatory factor analysis resulted in the identification of four dimensions: organization, workload, instruction, and learning. Afterward, a structural model was proposed to examine the relationships among the four factors. The model proposed that students' perceptions of the teacher's organization, workload, and instructional abilities influence their perception of learning. Findings indicated that the three constructs have a significant positive impact on students'perception of learning and explain 78% of the variance in perception of learning.
The How and Who of Strategy Making: Models and Appropriateness for Firms in Hospitality and Tourism Industries
Authors: Harrington Robert J.
Published: March 2006

A strategy-making process typology of ideal types is proposed describing salient dimensions from previous research. Two main dimensions are described as deliberate-emergent and individualistic-collective approaches. These dimensions address research questions of “how” strategies are formulated or implemented and “who” is involved in the process. It is proposed that, in general, firms adapt these dimensions in the strategy-making process to the level of dynamism and complexity in the environment. Further discussion provides insight into appropriate choices of strategy-making process models for firms in the food-service industry and expresses the need for researchers and managers to consider the degree and type of dynamism and complexity, firm size, level of analysis, level of strategy or tactic, culture, and institutional factors. It is suggested that service firms have a potential need to utilize multiple models simultaneously to affect conflicting objectives of control and adaptability.
Market Segmentation Based on Tourists’ Dining Preferences
Authors: Yüksel Atila , Yüksel Fisun
Published: March 2006

Managerial benefits of market segmentation have been justified; however, incorporation of this concept into restaurant management philosophy is limited, particularly in tourist resorts. A factor analytic approach undertaken in this article revealed that there were different tourist dining segments, developing their restaurant selection decisions based on different aspects of restaurant services, which requires segment-specific marketing and management strategies. The analysis identified five distinct tourist dining segments that take different sets of elements into account when making their restaurant selection decision. Marketing implications of the study findings are discussed.
A Review of Disparate Approaches to Strategy Implementation in Hospitality Firms
Authors: Okumus Fevzi , Roper Angela
Published: March 2006

In the field of strategy, most research has focused on earlier stages of the strategic management process, namely, analysis and formulation. Research to date has failed to recognize that it is at the implementation stage where the process most often breaks down. A number of disparate approaches to strategic management have emerged in the field, and each of them has different and often contrasting implications for how strategies should be developed and executed. The authors compare and contrast the implications of these approaches regarding how companies can best implement their strategies successfully. The authors review previous strategy implementation research in the strategic management and hospitality management fields from the perspective of five different schools of thought. The article ends by summarizing the key findings of the review and also gives further information about the next stages of a research project into strategy implementation in a sample of international hotel groups.
An Examination of Leasing Policy, Tax Rates, and Financial Stability in the Restaurant Industry
Authors: Upneja Arun , Dalbor Michael C.
Published: March 2006

Prior research has examined the relationship between debt financing and marginal tax rates to help explain the capital structure choice of firms. However, this type of measure is subject to an endogeneity problem, whereby an examination of postfinancing tax rates and debt financing produces a spurious negative relationship. Therefore, a before-financing tax rate may be a more accurate indicator of the use of debt financing versus leasing. This article uses both tax rate estimates to examine the relationship between tax rates and leasing behavior for a sample of restaurant firms. The authors also document a negative relation between the use of operating leases and the marginal tax rate faced by the firm and compare the accuracy of the two tax rate measures in predicting leasing and debt policy. Finally, the authors examine the relationship between leasing behavior and a firm’s financial stability.
Teenage Employment in the Hospitality Industry: An Exploratory Study
Authors: Milman Ady
Published: March 2006

This study explored perceptions of teens regarding key employment issues that were important in selecting and retaining their places of employment. A sample of 156 high school students working in the hospitality industry and in other industries identified several key employment variables that are important for teens. Although there were no statistically significant differences between hospitality and nonhospitality students, the findings revealed that teens preferred to work for companies that offer flexible scheduling and are located close to home. In selecting their next jobs, teens preferred to work for companies respected by others, with friendly coworkers, and for companies with clear-cut rules. Recommendations for employers and career guidance counselors are discussed. These include convenient scheduling, better supervision, a comfortable working environment, and provision of transportation to work.
Benchmarking: Comparing Discounted Business Rates among Lodging Companies
Authors: Boger Carl A. , Cai Liping A. , Lin Li-Chun
Published: March 2006

Yield management systems focus on the appropriate amount and depth of rate categories to maximize revenue for lodging properties. However, it is the interaction between reservationists and consumers that determines the room price. This study identified and compared different levels of discounting among various lodging companies. The findings should assist managers in benchmarking the current discounting practices in lodging companies.
Identification of Liquid Pressure in Pores of Baked Clay Tiles During Freezing-Thawing Cycles
Authors: Wardeh G. , Perrin B.
Published: March 2006

The durability of certain products used in roofing tiles depends on the boundary conditions during freezing as well as the texture of the porous material. The present article is an attempt to understand the effect of these boundary conditions on the physical state of the liquid phase during its solidification. From the experimental strains, the pressure developed in the porosity is calculated and thus the pressure of crystallization is identified. This step allows the pressure of the liquid phase to be deduced. For saturated products, the water is subjected to an overpressure during the freezing test and placing a wet cloth in contact with the tiles can increase its magnitude.
The effect of fetal hemoglobin on the survival characteristics of sickle cells
Authors: Franco Robert S. , Yasin Zahida , Palascak Mary B. , Ciraolo Peter , Joiner Clinton H. , Rucknagel Donald L.
Published: March 2006

The determinants of sickle red blood cell (RBC) life span have not been well-defined but may include both intrinsic factors (eg, the tendency to sickle) and extrinsic factors (eg, the capacity of the reticuloendothelial system to remove defective RBCs). Fetal hemoglobin (HbF) is heterogeneously distributed among sickle RBCs; F cells contain 20% to 25% HbF, whereas the remainder have no detectable HbF (non-F cells). Autologous sickle RBCs were labeled with biotin and reinfused to determine overall survival, non–F- and F-cell survival, and time-dependent changes in HbF content (%HbF) for the surviving F cells. A total of 10 patients were enrolled, including 2 who were studied before and after the percentage of F cells was increased by treatment with hydroxyurea. As expected, F cells survived longer in all subjects. Non–F-cell survival correlated inversely with the percentage of F cells, with the time for 30% cell survival ranging from 6 days in patients with more than 88% F cells to 16 days in patients with less than 16% F cells. As the biotin-labeled RBCs aged in the circulation, the HbF content of the surviving F-cell population increased by 0.28%/d ± 0.21%/d, indicating that within the F-cell population those with higher HbF content survived longer.
Targeted disruption of the hepcidin 1 gene results in severe hemochromatosis
Authors: Lesbordes-Brion Jeanne-Claire , Viatte Lydie , Bennoun Myriam , Lou Dan-Qing , Ramey Guillemette , Houbron Christophe , Hamard Ghislaine , Kahn Axel , Vaulont Sophie
Published: March 2006

We previously reported that mice made deficient for the transcriptional factor USF2 fail to express hepcidin 1 and hepcidin 2 genes as a consequence of targeted disruption of the Usf2 gene lying just upstream in the locus. These mice developed an iron overload phenotype with excess iron deposition in parenchymal cells and decreased reticuloendothelial iron. At that time, although the role of USF2 was still confounding, we proposed for the first time the role of hepcidin as a negative regulator of iron absorption and iron release from macrophages. Accordingly, we subsequently demonstrated that hyperexpression of hepcidin 1, but not hepcidin 2, resulted in a profound hyposideremic anemia. To analyze the consequences of hepcidin 1 deletion on iron metabolism without any disturbance due to USF2 deficiency, we disrupted the hepcidin 1 gene by targeting almost all the coding region. Confirming our prior results, Hepc1–/– mice developed early and severe multivisceral iron overload, with sparing of the spleen macrophages, and demonstrated increased serum iron and ferritin levels as compared with their controls.
Lymphoid interstitial pneumonia: clinical features, associations and prognosis
Authors: Cha S-I. , Fessler M. B. , Cool C. D. , Schwarz M. I. , Brown K. K.
Published: March 2006

Lymphoid interstitial pneumonia (LIP) is rare and its clinical course incompletely described. The aim of this study was to examine the clinical features, associations and prognosis of surgical lung biopsy-proven LIP. The study group consisted of 15 subjects encountered over a 14-yr period.

The majority of subjects were females (n = 11) and the mean age was 47 yrs (range 17–78 yrs). Underlying systemic immune disorders were frequent, including Sjögren's syndrome (n = 8), rheumatoid arthritis, systemic lupus erythematosus, polymyositis, common variable immunodeficiency and dysproteinaemia. Only three patients were classified as “idiopathic”. Presenting symptoms were dominated by dyspnoea and cough. Restrictive physiology, reduced diffusion capacity (62.5±18.4% predicted) and bronchoalveolar lavage lymphocytosis (30.5±29.1% pred) were noted. Thirteen patients received corticosteroid therapy. Of the nine whose response could be assessed, four showed clinical improvement and four were stable. Overall, median survival was 11.5 yrs. Of the seven patients who died, respiratory problems were the primary cause of death in three. Conversion to lymphoma was not identified.

In conclusion, histopathological lymphoid interstitial pneumonia is commonly associated with immune system dysregulation, with idiopathic lymphoid interstitial pneumonia being extremely rare. Clinical stability or improvement with corticosteroids can be expected; however, survival remains impaired.
Allergic lung inflammation induces pulmonary vascular hyperresponsiveness
Authors: Witzenrath M. , Ahrens B. , Kube S. M. , Hocke A. C. , Rosseau S. , Hamelmann E. , Suttorp N. , Schütte H.
Published: March 2006

Pulmonary arterial vasoconstriction is an important early component of pulmonary hypertension. Inflammatory mechanisms play a prominent role in the pathogenesis of pulmonary hypertension. The present authors investigated the potential role of acute allergic lung inflammation for alterations in pulmonary haemodynamics.

BALB/c mice were intraperitoneally sensitised to ovalbumin and challenged by ovalbumin inhalation. Subsequently, lungs were ventilated and perfusedex vivo, and pulmonary arterial pressure (Ppa) was continuously monitored.

Isolated perfused lungs of allergen-sensitised and -challenged mice showed five-fold enhanced Pparesponses to serotonin, which is reported to be a significant contributor to pulmonary hypertension in humans. This increase inPpawas abolished by the serotonin receptor-2A antagonist ketanserin, but not the serotonin receptor-1B antagonist GR127935. Intracellular signalling to serotonin involved phosphatidylcholine-specific phospholipase C and protein kinase C, as well as Rho-kinase, as assessed by employing the specific inhibitors D609, bisindolylmaleimide and Y27632, respectively. In addition to serotonin, impressively enhancedPpaincreases in allergic lungs were also evoked by the thromboxane receptor agonist U46619, angiotensin II and endothelin-1.

In conclusion, allergic lung inflammation was accompanied by impressive pulmonary vascular hyperresponsiveness. These results suggest a possible role for allergic inflammation in the development of pulmonary arterial hypertension.
Ventilation inhomogeneity in α1-antitrypsin-deficient emphysema
Authors: Fregonese L. , van Veen H. P. A. A. , Sterk P. J. , Stolk J.
Published: March 2006

The slope of phase III of the single-breath nitrogen wash-out test (sbN2-test) measures ventilation inhomogeneity and, in smokers, is strongly associated with small airways pathology. The present authors aimed to study ventilation inhomogeneity in emphysema related to type Z α1-antitrypsin (AAT) and to assess its relationship with indices of parenchymal damage and airways obstruction.

A total of 18 subjects, consisting of ex-smokers with type Z AAT and emphysema (confirmed by computed tomography scan), were studied in a cross-sectional design. Post-bronchodilation flow–volume curves and gas transfer parameters were measured; sbN2-test curves were obtained and the slope of phase III was determined.

The mean value of the slope (4.6±1.3% N2·L-1) was higher than reference values +2sd; it was significantly correlated with the transfer factor of the lung for carbon monoxide (R =  -0.75) and the transfer coefficient of the lung for carbon monoxide (R =  −0.58), but not with airways obstruction. There was no correlation between phase III slope values and cumulative smoking.

In patients with type Z α1-antitrypsin emphysema, the increased ventilation inhomogeneity predominantly reflects parenchymal abnormalities, demonstrating that measurement of airways obstruction is not sufficient to characterise the disease. Determination of the sensitivity of the single-breath nitrogen wash-out test slope in detecting disease progression may give complementary information to spirometry.
Antioxidant enzyme activities and lipid peroxidation products in heart tissue of subacute and subchronic formaldehyde-exposed rats: a preliminary study
Authors: Güleç Mukaddes , Songur Ahmet , Sahin Semsettin , Ozen Oguz A , Sarsilmaz Mustafa , Akyol Omer
Published: March 2006

Objective: The aim of this experimental study was to evaluate the oxidant/antioxidant status and lipid peroxidation in the heart of rats exposed to formaldehyde (FA) inhalation for four weeks (subacute) or 13 weeks (subchronic) continuously. Methods and results: Sixty Wistar albino rats were divided into six groups randomly (ten in each group). The first and second groups were used as subacute and subchronic control groups. FA gas was generated from paraformaldehyde and pumped to a closed glass chamber. Rats were exposed to atmosphere containing 10 and 20 ppm FA (8 h/day, five days per week) during a four and 13 weeks period. After heart tissues were obtained and homogenized, thiobarbituric acid-reactant substances (TBARS) and nitric oxide (NO) levels, as well as superoxide dismutase (SOD) and catalase (CAT) activities, were measured. There were statistically significant findings in SOD and CAT activities in the study groups compared to the control group. Heart tissue SOD level was increased in the group exposed to subacute 10 and 20 ppm FA inhalation compared to the control group (P≤0.011 and ≤0.0001). In addition, heart tissue SOD level was increased in the group exposed to subchronic 10 and 20 ppm FA inhalation compared to the corresponding control group (P≤0.001). On the other hand, there were statistically significant decreases in CAT activity in subacute 10 and 20 ppm groups compared to the corresponding control group (P≤0.012 and ≤0.039, respectively). Although not significant, TBARS levels were increased in both subacute 10 ppm (P=0.100) and subchronic 20 ppm (P=0.053) groups compared to their corresponding control groups. Tissue NO levels were unchanged upon FA inhalation. In the correlation analyses, a meaningful relationship between SOD and CAT activities in subchronic 10 ppm group (r=-0.685, P≤0.029); SOD activity and TBARS level in subchronic 20 ppm group (r=-0.675, P≤0.032); and CAT activity and NO level in subchronic 20 ppm group (r=-0.810, P≤0.005) were found. Conclusion: From the findings of our study, it can be interpreted that subacute and subchronic FA inhalation may stimulate oxidative stress and thus, some secondary toxic effects in cardiac cells and tissue. This increase in the oxidative stress could not induce lipid peroxidation in the membranous structure of cardiac cells. An increased SOD enzyme activity was thought to be secondary to decreased CAT activity, as a compensation mechanism, preventing heart tissue from destruction induced by FA.
Effects of dioxins on the quantitative levels of immune components in infants
Authors: Kaneko Hideo , Matsui Eiko , Shinoda Shinnji , Kawamoto Norio , Nakamura Yosikazu , Uehara Ritei , Matsuura Nobuo , Morita Masatoshi , Tada Hiroshi , Kondo Naomi
Published: March 2006

Dioxins (polychlorinated dibenzo-p-dioxin (PCDD)=polychlorinated dibenzofuran (PCDF)) and polychlorinated biphenyls (PCBs) are potentially hazardous compounds and have structural similarity with thyroid hormones. Animal studies have demonstrated that PCDDs, PCDFs and PCBs can alter immune functions. However, in humans it is not yet elucidated whether dioxins contained in breast milk have any effects on the immune functions in infants. To investigate the effects of dioxins on the immune system, we compared the quantitative levels of immune components between a breast-fed group and bottle-fed group, in which dioxin concentration is almost zero. Ratios of immune cells, such as CD4= and CD8= T-lymphocytes, as well as B-lymphocytes (CD19= and/or CD20=) and NK cells (CD16=, CD56=) in peripheral blood lymphocytes, serum immunoglobulin level, and level of specific IgE antibody to allergens in the venous blood at 12 months of age were assessed in a subgroup of 281 infants. The relationship of post-natal dioxin exposure via breast feeding with the ratio of immunological markers and the level of humoral antibodies up to 12 month of age was not demonstrated. In conclusion, it would appear that the content of dioxins in breast milk in the Japanese general population is not enough to induce any change in theses-examined immunological parameters during the first year of life, although long-term effects remain to be evaluated.
Influence of thyroxine and n-propylthiouracil on nephro-toxicity of inorganic arsenic in rat
Authors: Rana SVS , Allen Tanu
Published: March 2006

The effect of hyper or hypoactive thyroid on the renal toxicity of arsenic trioxide has been studied in rats. It was observed that pre-treatment of rats with thyroxine stimulates arsenic excretion in urine. The anti-thyroid drug n-propylthiouracil (PTU), inhibits the accumulation of arsenic in renal tissue. Both treatments affect the renal pathology. Histopathological lesions are less severe in PTU and arsenic-treated rats in comparison to thyroxine and arsenic-treated rats. Ultrastructural studies support light microscopical observations. An adaptive response was noticed against arsenic in PTU pre-treated rats. We attribute this response to decreased glutathione-S-transferase (GSH) activity and increased GSH synthesis in the kidney. A relationship between thyroidal activity and arsenic toxicity is suggested by present observations.
Sp8controls the anteroposterior patterning at the midbrain-hindbrain border
Authors: Griesel Gundula , Treichel Dieter , Collombat Patrick , Krull Jens , Zembrzycki Andreas , van den Akker Willem M. R. , Gruss Peter , Simeone Antonio , Mansouri Ahmed
Published: March 2006

The specification of neuronal cell types in the developing neural tube is orchestrated by signaling centers. However, how patterned territories of the central nervous system (CNS) are organized into structures with appropriate size and shape is still unclear. We report that in the absence of the mouse transcription factor mBtd/Sp8, a posterior shift of the isthmic organizer(IsO) occurs, suggesting a crucial role for Sp8 in this process. In addition,large patches of cells ectopically expressing Fgf8, Otx2 and/or Wnt1 in the rostral hindbrain are detected in Sp8 mutant embryos. In this context, midbrain dopaminergic neurons are found posterior to the IsO. Furthermore, we provide evidence that cell proliferation in the mid-and hindbrain is tightly controlled by Sp8 activity. Our observations are consistent with a role for Sp8 in restricting Fgf8 expression at the IsO.
Inactivation of aPKCλ results in the loss of adherens junctions in neuroepithelial cells without affecting neurogenesis in mouse neocortex
Authors: Imai Fumiyasu , Hirai Syu-ichi , Akimoto Kazunori , Koyama Hiromichi , Miyata Takaki , Ogawa Masaharu , Noguchi Shigeru , Sasaoka Toshikuni , Noda Tetsuo , Ohno Shigeo
Published: March 2006

In developing mammalian telencephalon, the loss of adherens junctions and cell cycle exit represent crucial steps in the differentiation of neuroepithelial cells into neurons, but the relationship between these cellular events remains obscure. Atypical protein kinase C (aPKC) is known to contribute to junction formation in epithelial cells and to cell fate determination for Drosophila neuroblasts. To elucidate the functions of aPKCλ, one out of two aPKC members, in mouse neocortical neurogenesis, a Nestin-Cre mediated conditional gene targeting system was employed. In conditional aPKCλ knockout mice, neuroepithelial cells of the neocortical region lost aPKCλ protein at embryonic day 15 and demonstrated a loss of adherens junctions, retraction of apical processes and impaired interkinetic nuclear migration that resulted in disordered neuroepithelial tissue architecture. These results are evidence that aPKCλ is indispensable for the maintenance of adherens junctions and may function in the regulation of adherens junction integrity upon differentiation of neuroepithelial cells into neurons. In spite of the loss of adherens junctions in the neuroepithelium of conditional aPKCλ knockout mice, neurons were produced at a normal rate. Therefore, we concluded that, at least in the later stages of neurogenesis, regulation of cell cycle exit is independent of adherens junctions.
Sonic hedgehog regulates Gli activator and repressor functions with spatial and temporal precision in the mid/hindbrain region
Authors: Blaess Sandra , Corrales JoMichelle D. , Joyner Alexandra L.
Published: March 2006

The midbrain and anterior hindbrain offer an ideal system in which to study the coordination of tissue growth and patterning in three dimensions. Two organizers that control anteroposterior (AP) and dorsoventral (DV) development are known, and the regulation of AP patterning by Fgf8 has been studied in detail. Much less is known about the mechanisms that control mid/hindbrain development along the DV axis. Using a conditional mutagenesis approach, we have determined how the ventrally expressed morphogen sonic hedgehog (Shh)directs mid/hindbrain development over time and space through positive regulation of the Gli activators (GliA) and inhibition of the Gli3 repressor(Gli3R). We have discovered that Gli2A-mediated Shh signaling sequentially induces ventral neurons along the medial to lateral axis, and only before midgestation. Unlike in the spinal cord, Shh signaling plays a major role in patterning of dorsal structures (tectum and cerebellum). This function of Shh signaling involves inhibition of Gli3R and continues after midgestation. Gli3R levels also regulate overall growth of the mid/hindbrain region, and this largely involves the suppression of cell death. Furthermore, inhibition of Gli3R by Shh signaling is required to sustain expression of the AP organizer gene Fgf8. Thus, the precise spatial and temporal regulation of Gli2A and Gli3R by Shh is instrumental in coordinating mid/hindbrain development in three dimensions.
Wnt signaling establishes anteroposterior neuronal polarity and requires retromer inC. elegans
Authors: Prasad Brinda C. , Clark Scott G.
Published: March 2006

Secreted Wnt proteins influence neural connectivity by regulating axon guidance, dendritic morphogenesis and synapse formation. We report a new role for Wnt and Frizzled proteins in establishing the anteroposterior polarity of the mechanosensory neurons ALM and PLM in C. elegans. Disruption of Wnt signaling leads to a complete inversion of ALM and PLM polarity: the anterior process adopts the length, branching pattern and synaptic properties of the wild-type posterior process, and vice versa. Different but overlapping sets of Wnt proteins regulate neuronal polarity in different body regions. Wnts act directly on PLM via the Frizzled LIN-17. In addition, we show that they are needed for axon branching and anteriorly directed axon growth. We also find that the retromer, a conserved protein complex that mediates transcytosis and endosome-to-Golgi protein trafficking, plays a key role in Wnt signaling. Deletion mutations of retromer subunits cause ALM and PLM polarity, and other Wnt-related defects. We show that retromer protein VPS-35 is required in Wnt-expressing cells and propose that retromer activity is needed to generate a fully active Wnt signal.
Kidnapping of chicks in emperor penguins: a hormonal by-product?
Authors: Angelier Frédéric , Barbraud Christophe , Lormée Hervé , Prud'homme François , Chastel Olivier
Published: March 2006

The function and causes of kidnapping juveniles are little understood because individuals sustain some breeding costs to rear an unrelated offspring. Here we focus on the proximal causes of this behaviour in emperor penguins (Aptenodytes forsteri), whose failed breeders often kidnap chicks. We experimentally tested the hypothesis that kidnapping behaviour was the result of high residual levels of prolactin (PRL), a hormone involved in parental behaviour. Penguins with artificially decreased PRL levels by bromocriptine administration kidnapped chicks less often than control penguins. Within the bromocriptine treated group, kidnapping behaviour was not totally suppressed and the probability of kidnapping a chick was positively correlated to PRL levels measured before treatment. During breeding, emperor penguins have to forage in remote ice-free areas. In these birds, PRL secretion is poorly influenced by chick stimuli and has probably evolved to maintain a willingness to return to the colony after a long absence at sea. Therefore, penguins that have lost their chick during a foraging trip still maintain high residual PRL levels and this, combined with colonial breeding,probably facilitates kidnapping. We suggest that kidnapping in non-cooperative systems may result from a hormonal byproduct of a reproductive adaptation to extreme conditions.
Passive mechanical properties of legs from running insects
Authors: Dudek Daniel M. , Full Robert J.
Published: March 2006

While the dynamics of running arthropods have been modeled as a spring-mass system, no such structures have been discovered that store and return energy during bouncing. The hindleg of the cockroach Blaberus discoidalis is a good candidate for a passive, vertical leg spring because its vertically oriented joint axes of rotation limit the possibility of active movements and contributions of muscle properties. We oscillated passive legs while measuring force to determine the leg's dynamic, mechanical properties. The relative dimensionless stiffness of an individual cockroach leg was equal to that estimated for a single leg of a biped or quadruped. Leg resilience ranged from 60 to 75%, affording the possibility that the leg could function as a spring to store and return the mechanical energy required to lift and accelerate the center of mass. Because hysteresis was independent of oscillation frequency,we rejected the use of a Voigt model – a simple spring in parallel with a viscous damper. A hysteretic damping model fit the cockroach leg force–displacement data over a wide range of frequencies and displacement using just two parameters. Rather than simply acting as a spring to minimize energy, we hypothesize that legs must manage both energy storage and absorption for rapid running to be most effective.
Temporal pattern cues in vibrational risk assessment by embryos of the red-eyed treefrog, Agalychnis callidryas
Authors: Warkentin Karen M. , Caldwell Michael S. , McDaniel J. Gregory
Published: March 2006

The embryos of red-eyed treefrogs, Agalychnis callidryas, use vibrations transmitted through their arboreal egg clutch to cue escape hatching behavior when attacked by egg-eating snakes. Hatching early increases the risk of predation in the water, so embryos should avoid it unless they are in danger. We exposed egg clutches to intermittent vibrations with different combinations of vibration duration and spacing to examine the role of simple temporal pattern cues in the escape hatching response. Stimuli were bursts of synthetic white noise from 0 to 100 Hz, including the range of frequencies with substantial energy in snake attacks, and had approximately rectangular amplitude envelopes. Embryos hatched in response to a small range of temporal patterns and not in response to many others, rather than hatching to most vibrations except for certain patterns perceived as safe. Neither cycle length nor duty cycle predicted hatching response, except at extreme values where no hatching occurred; the highest energy stimuli elicited little or no hatching. Both vibration duration and inter-vibration interval strongly affected the hatching response. The highest levels of hatching were to durations of 0.5 s combined with intervals of 1.5–2.5 s, and hatching decreased gradually with increasing difference of either duration or interval from these most effective stimuli. Vibration duration and interval appear to function as two necessary elements of a composite cue, rather than as redundant cues. This increases response specificity and reduces the range of stimuli that elicit hatching, likely reducing the chance of hatching unnecessarily in a benign disturbance. Vibration-cued hatching in A. callidryas embryos offers an opportunity to experimentally assess the behavioral decision rules underlying an effective and costly anti-predator defense.
Heterothermy of free-living Arabian sand gazelles (Gazella subgutturosa marica) in a desert environment
Authors: Ostrowski Stéphane , Williams Joseph B.
Published: March 2006

To test whether free-living desert ungulates employ heterothermy to reduce water loss, we measured core body temperature (Tb) of six free-living Arabian sand gazelles (Gazella subgutturosa marica), a small desert antelope (12–20 kg) that lives in the deserts of Saudi Arabia, where air temperature (Ta) often exceeds 40°C. We found that the mean daily Tb varied by 2.6±0.8°C during summer (June–July) and 1.7±0.3°C during winter (January–February); over both seasons, mean Tb was 39.5±0.2°C. During the day, in summer, Tb increased by more than 2°C when Ta>Tb and declined at night when Ta<Tb, suggesting that gazelles stored heat during day and dissipated it by non evaporative means during night. The minimum Tb was lower in summer(38.2±0.5°C) than in winter (38.6±0.3°C) despite the fact that the gradient between Tb and Ta was larger and solar radiation was lower in winter. Correlation between daily variation of Tb and mean,maximal Tas were significant in summer, but not in winter. To dissipate the amount of heat stored by gazelles would require an evaporative water loss of 33.5 ml H2O day–1 in summer and 23.2 ml H2O day–1 in winter.

We tested whether the amplitude of daily variation in Tb was influenced by the level of water provided to six captive sand gazelles maintained under controlled conditions in summer. The daily amplitude of Tb was increased by 1.4°C when gazelles were denied drinking water but supplied with pre-formed water in food, and by 1.1°C when they were denied both water and food. Gazelles denied only drinking water increased the amplitude of variation in Tb, whereas when denied both food and water, they seemed to undergo a dehydration-hyperthermia, with increased mean and maximal Tb values but no decrease of minimal Tb.

Free-ranging and captive gazelles surviving on pre-formed water in natural food used heterothermy during summer with no elevation of plasma osmolality,indicating that they were not in a state of dehydration. Our data on variation in Tb of gazelles provide an example of a small desert ungulate employing heterothermy to reduce evaporative water loss that would otherwise be required to maintain normothermic Tb.
Median fin function in bluegill sunfishLepomis macrochirus:streamwise vortex structure during steady swimming
Authors: Tytell Eric D.
Published: March 2006

Fishes have an enormous diversity of body shapes and fin morphologies. From a hydrodynamic standpoint, the functional significance of this diversity is poorly understood, largely because the three-dimensional flow around swimming fish is almost completely unknown. Fully three-dimensional volumetric flow measurements are not currently feasible, but measurements in multiple transverse planes along the body can illuminate many of the important flow features. In this study, I analyze flow in the transverse plane at a range of positions around bluegill sunfish Lepomis macrochirus, from the trailing edges of the dorsal and anal fins to the near wake. Simultaneous particle image velocimetry and kinematic measurements were performed during swimming at 1.2 body lengths s–1 to describe the streamwise vortex structure, to quantify the contributions of each fin to the vortex wake, and to assess the importance of three-dimensional flow effects in swimming.

Sunfish produce streamwise vortices from at least eight distinct places,including both the dorsal and ventral margins of the soft dorsal and anal fins, and the tips and central notched region of the caudal fin. I propose a three-dimensional structure of the vortex wake in which these vortices from the caudal notch are elongated by the dorso-ventral cupping motion of the tail, producing a structure like a hairpin vortex in the caudal fin vortex ring. Vortices from the dorsal and anal fin persist into the wake, probably linking up with the caudal fin vortices. These dorsal and anal fin vortices do not differ significantly in circulation from the two caudal fin tip vortices. Because the circulations are equal and the length of the trailing edge of the caudal fin is approximately equal to the combined trailing edge length of the dorsal and anal fins, I argue that the two anterior median fins produce a total force that is comparable to that of the caudal fin. To provide additional detail on how different positions contribute to total force along the posterior body, the change in vortex circulation as flow passes down the body is also analyzed. The posterior half of the caudal fin and the dorsal and anal fins add vortex circulation to the flow, but circulation appears to decrease around the peduncle and anterior caudal fin. Kinematic measurements indicate that the tail is angled correctly to enhance thrust through this interaction. Finally, the degree to which the caudal fin acts like a idealized two-dimensional plate is examined: approximately 25% of the flow near the tail is accelerated up and down, rather than laterally, producing wasted momentum,a loss not present in ideal two-dimensional theories.
Molecular springs and muscles: Progress toward augmented electromechanical actuation
Authors: Almutairi Adah , Yoon Kunsang , Tham Fook , Marsella Michael J.
Published: March 2006

The application of 3,3'-diphenyl-2'2-bithiophene as a helical scaffold capable of electrochemical polymerization to yield the corresponding polythiophene is reported. One unique feature of this monomer is its theoretically predicted (DFT) ability to mimic redox-stimulated contraction and expansion. This ability, coupled with traditional electromechanical actuation properties of bulk, redox-active conjugated polymers (CPs), yields a polymeric "molecular muscle" capable of both contraction and expansion.