bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of natural and manmade disasters on household welfare
Authors: Sawada Yasuyuki
Published: August 2010

In this article, we provide selective evidence on the impact of natural and manmade disasters on household welfare. First, we consider ex ante risk management and ex post risk‐coping behaviors separately, showing evidence from the Asian economic crisis, earthquakes, and tsunami disasters. Second, we differentiate idiosyncratic risks from nondiversifiable aggregate risks that characterize a disaster. We also discuss the difficulties of designing index‐type insurance against natural disasters, which are often rare, unforeseen events. Then, we investigate the role of self‐insurance against large‐scale disasters under which formal or informal mutual insurance mechanisms are largely ineffective. Credit accessibility is identified as one of the key factors facilitating risk‐coping strategies.
Globalization, privatization, and vertical coordination in food value chains in developing and transition countries
Authors: Swinnen Johan F. M. , Maertens Miet
Published: August 2010

Food and agricultural commodity value chains in developing and transition countries have undergone tremendous changes in the past decades. Companies and property rights have been privatized, markets liberalized, and economies integrated into global food systems. The liberalization and privatization initially caused the collapse of state‐controlled vertical coordination. More recently, private vertical coordination systems have emerged and are growing rapidly as a response to consumer demand for food quality and safety on the one hand and the farms' production constraints caused by factor market imperfections. In this article we (1) demonstrate the importance of these changes, (2) discuss the implications for efficiency and equity, and (3) provide empirical evidence on the effects in several developing and transition countries.
Food regulation and trade under the WTO: ten years in perspective
Authors: Orden David , Roberts Donna
Published: August 2010

This article reviews the performance of the World Trade Organization in the oversight of national regulatory decisions affecting agricultural and food trade. A picture emerges of modest international disciplines on the regulatory decisions of sovereign nations and the need for ongoing improvements. A road map to regulations is presented and empirical assessments of the effects of technical regulation on trade are reviewed. Conflicts over sanitary and phytosanitary barriers raised in the relevant World Trade Organization committee are summarized and formal dispute settlement cases involving technical trade barriers are evaluated. Drawing on these reviews, suggestions are made for improving international food regulation.
Technological progress for sustaining food‐population balance: achievement and challenges
Authors: Hossain Mahabub
Published: August 2010

The growth in land productivity in rice cultivation has slowed down substantially since the early 1990s due to technological progress reaching its limit in the irrigated ecosystem and nonavailability of suitable technologies for the unfavorable rainfed environments. This development raises concern regarding the world's ability to meet the food‐population balance in the coming decades. Rice research must deal with a number of difficult problems to meet the challenge: raising the yield ceilings of the current available rice varieties; protecting the past yield gains in the irrigated ecosystem; and using biotechnology tools to develop high yielding varieties for the rainfed systems that are tolerant to drought, submergence, and problem soils. The speed and extent of meeting these challenges depends on the level of resources that can be mobilized to support crop improvement research in the public sector.
Agricultural research and policy for better health and nutrition in developing countries: a food systems approach
Authors: Pinstrup‐Andersen Per
Published: August 2010

This article is about the two‐way causal relationships between the global food system and health and nutrition. It argues that the global food system begins and ends with health and that the prioritization and implementation of agricultural research and policy should consider health and nutrition effects. An integrated health and food policy approach is likely to be more effective in achieving both health and economic development goals that the current practice of separate sectorial policies. The article identifies a large number of health and nutrition factors affecting and affected by the food system and suggests research and policies to enhance positive effects and reduce negative ones.
Coping with drought in rice farming in Asia: insights from a cross‐country comparative study
Authors: Pandey Sushil , Bhandari Humnath , Ding Shijun , Prapertchob Preeda , Sharan Ramesh , Naik Dibakar , Taunk Sudhir K. , Sastri Asras
Published: August 2010

Drought is a major constraint affecting rice production, especially in rainfed areas of Asia. Despite its importance in rice‐growing areas, the magnitude of economic losses arising from drought, its impact on farm households, and farmers' drought coping mechanisms are poorly understood. This article provides insights into these aspects of drought based on a cross‐country comparative analysis of rainfed rice‐growing areas in southern China, eastern India, and northeast Thailand. The economic cost of drought is found to be substantially higher in eastern India than in the other two countries. Higher probability and greater spatial covariance of drought and less diversified farming systems with rice accounting for a larger share of household income are the main reasons for this higher cost of drought in eastern India. Farmers deploy various coping mechanisms but such mechanisms are largely unable to prevent a reduction in income and consumption, especially in eastern India. As a result, welfare consequences on poor farmers are substantial with a large number of people falling back into poverty during drought years. The overall implications for technology design and for policy improvements for drought mitigation and drought relief are discussed in the light of the empirical findings of the study.
Designing frameworks to deliver unknown information to support market‐based instruments
Authors: Eigenraam Mark , Strappazzon Loris , Lansdell Nicola , Beverly Craig , Stoneham Gary
Published: August 2010

This article reports on an Australian auction to procure multiple environmental outcomes: EcoTender. EcoTender uses a Catchment Modelling Framework (CMF) to estimate the impact landholder actions have on carbon, terrestrial biodiversity, aquatic function (water quality and quantity), and saline land area. This framework solves the problem of linking paddock‐scale land use and management to catchment‐scale environmental outcomes. This is the first time a market‐based instrument has been fully integrated from desk to field with a biophysical model for the purchase of multiple environmental outcomes. A multiple outcome auction provides several new economic and scientific challenges. This article discusses the EcoTender approach to incorporating agency preferences, modeling the joint production of environmental outcomes and reporting environmental scores. Results indicate that linking EcoTender to the carbon market reduced the cost of procuring the environmental goods by 26%. Further, preliminary estimates show that the environmental gains from scoring the joint production of multiple outcomes are between 30% and 50% to the agency.
Meta‐analysis of general and partial equilibrium simulations of Doha Round outcomes
Authors: Hess Sebastian , Von Cramon‐Taubadel Stephan
Published: August 2010

Quantification of welfare changes due to trade liberalization plays a crucial role for political decision making. However, significant differences in simulated gains from liberalization do not serve to increase confidence in quantitative assessments based on trade models. A meta‐analysis of trade simulations under the WTO Doha Round is employed to identify model characteristics that influence the magnitude of simulation results. Findings from a simple regression model are plausible and show that each simulation experiment represents a complex interaction of model characteristics and experimental settings that may not easily be communicated to nonexperts. Meta‐analysis proves to be useful for empirically assessing this complexity.
Land inequality and economic growth: a dynamic panel data approach
Authors: Fort Ricardo
Published: August 2010

The growing body of literature devoted to studying the impact of inequality on economic growth has centered its attention on the income distribution effect, even though the theoretical relationships are more related to assets distribution. While some recent studies have tried to overcome this limitation by introducing asset indicators, they meet new constraints when dealing only with time‐invariant measurements for this explanatory variable. This article provides a theoretical discussion and some novel empirical tests to better understand the relationships between assets distribution and economic growth. We assembled a new panel database that includes observations for more than 30 countries over the last three decades. The data include a time‐varying variable for changes in the Land Gini index over this period that enables us to overcome the limitations of previous studies. A system general method of moments (GMM) estimator is used to generate truly unbiased and consistent estimates for the parameters of interest. We explore some of the likely channels through which asset distribution and economic growth may be linked, paying particular attention to the role of secure property rights and the relations between land ownership and education. We find robust and significant negative signs for land inequality in the growth regressions, indicating that changes in asset distribution are an important factor for economic development.
A look into the nature of complex systems and beyond “Stonehenge” economics: coping with complexity or ignoring it in applied economics?
Authors: Noell Chris
Published: August 2010

Real‐world economic systems are complex in general but can be approximated by the “open systems” approach. Economic systems are very likely to possess the basic and advanced emergent properties (e.g., self‐organized criticality, fractals, attractors) of general complex systems. The theory of “self‐organized criticality” is proposed as a major source of dynamic equilibria and complexity in economic systems. This is exemplified in an analysis for self‐organized criticality of Danish agricultural subsectors, indicated by power law distributions of the monetary production value for the time period from 1963 to 1999. Major conclusions from the empirical part are: (1) The sectors under investigation are obviously self‐organizing and thus very likely to show a range of complex properties. (2) The characteristics of the power law distributions that were measured might contain further information about the state or graduation of self‐organization in the sector. Varying empirical results for different agricultural sectors turned out to be consistent with the theory of self‐organized criticality. (3) Fully self‐organizing sectors might be economically the most efficient. Finally, empirical implications of the results are discussed. Complexity theory should be considered as a valuable supplement to the existing analytical toolbox.
Do farmers benefit from participating in specialty markets and cooperatives? The case of coffee marketing in Costa Rica1
Authors: Wollni Meike , Zeller Manfred
Published: August 2010

Historically low prices in the conventional coffee market have caused financial and social hardship among coffee farmers. In the face of this crisis, specialty markets have attracted the attention of the international donor community. These market segments have shown consistent growth over the last decade and exhibit price premiums in international markets. Therefore, if higher prices are passed on to farmers, access to specialty markets could help to alleviate the crisis brought on by low prices in the conventional sector. The present study attempts to identify the factors that determine farmers' participation in specialized markets and whether participation in these markets leads to higher prices for farmers. A two‐stage model is used to analyze farmers' marketing decisions and their effect on the prices received. This procedure allows us to control for the endogeneity bias introduced by the marketing choice. Our results indicate that farmers participating in the specialty coffee segment do in fact receive higher prices than those participating in conventional channels. Additionally, we find that participation in cooperatives has a positive impact on the probability that a farmer chooses to grow specialty coffee and analogously on the prices that they receive. Based on these results, it seems that efforts to increase participation in the specialty coffee segment and in cooperatives would help to lessen some of the hardships brought on by low prices in the conventional coffee sector.
Food consumption impacts of adherence to dietary norms in the United States: a quantitative assessment
Authors: Srinivasan C. S.
Published: August 2010

Promotion of adherence to healthy‐eating norms has become an important element of nutrition policy in the United States and other developed countries. We assess the potential consumption impacts of adherence to a set of recommended dietary norms in the United States using a mathematical programming approach. We find that adherence to recommended dietary norms would involve significant changes in diets, with large reductions in the consumption of fats and oils along with large increases in the consumption of fruits, vegetables, and cereals. Compliance with norms recommended by the World Health Organization for energy derived from sugar would involve sharp reductions in sugar intakes. We also analyze how dietary adjustments required vary across demographic groups. Most socio‐demographic characteristics appear to have relatively little influence on the pattern of adjustment required to comply with norms. Income levels have little effect on required dietary adjustments. Education is the only characteristic to have a significant influence on the magnitude of adjustments required. The least educated rather than the poorest have to bear the highest burden of adjustment. Our analysis suggests that fiscal measures like nutrient‐based taxes may not be as regressive as commonly believed. Dissemination of healthy‐eating norms to the less educated will be a key challenge for nutrition policy.
Consumer willingness to pay for genetically modified food in Kenya
Authors: Kimenju Simon Chege , De Groote Hugo
Published: August 2010

Genetically modified (GM) crops are popular in many regions of the world, but their deployment in Africa is hindered by safety concerns and regulatory issues, although the continent is in dire need of boosting its food production. Although consumers' acceptance of GM food has been analyzed in many continents, no such studies have been conducted in Africa. Therefore, a survey of 604 consumers was conducted in Nairobi, Kenya, in 2003, to gauge consumers' awareness of GM crops, their willingness to pay (WTP) for GM food, and the factors that influence their WTP. Consumers' knowledge of GM crops was limited and only 38% of the 604 respondents were aware of GM crops. People in higher education and income groups were more aware than others. Regardless, people were generally appreciative of the technology, and a large majority (68%) would be willing to buy GM maize meal at the same price as their favorite brand. Consumers were, however, concerned about possible side effects, especially on the environment and biodiversity.

WTP was estimated using a double‐bounded dichotomous choice model, and the mean WTP was found to be 13.8% higher than the average price of non‐GM maize meal. Perceptions of health risk, and ethical and equity concerns had a negative influence on the likelihood of purchasing GM maize meal, whereas trust in government to ensure food quality had a positive influence on WTP. People with at least some secondary education and those in the high‐income category were more likely to purchase GM maize meal at the same price. The study concludes that, because awareness is still low, appropriate communications are needed to involve the consumer in the debate. Consumers' acceptance in this study was high, but the research needs to be expanded to rural areas, where most consumers live, and other survey methods need to be explored.
Yield quality and irrigation with saline water under environmental limitations: the case of processing tomatoes in California
Authors: Kan Iddo
Published: August 2010

Irrigation with saline water has a positive impact on some quality indices of processing tomatoes, but with concomitant reductions in output quantity. This article studies the impact of the trade‐off between these two factors on optimal water management under waterlogging and costly drainage‐disposal conditions. The focus is on the content of total soluble solids as a quality measure affecting prices paid by California processors to tomato growers. A function relating quality to water and salinity applications and a quality hedonic‐price function are estimated and introduced into a static, field‐level mathematical programming model. The model calculates optimal water management under environmental regulations associated with drainage disposal in California. Findings indicate that only when the quality effect is taken into account does blending fresh surface‐water with saline drain‐water become an optimal strategy. Management and policy implications on the regional scale are discussed.
Technical efficiency and environmental‐technological gaps in wheat production in Kerman province of Iran
Authors: Boshrabadi Hossein Mehrabi , Villano Renato , Fleming Euan
Published: August 2010

This article reports on an analysis of technical efficiency and environment‐technology gaps in wheat farming in Iran. A random sample of 676 farmers was selected from the province of Kerman in 2004. In this study, Kerman is divided into five regions based on climatic and geographical conditions. The province is situated in the south‐eastern part of Iran and contains substantial variations in climate.

The technical efficiency indices are computed using three approaches. First, a standard stochastic production frontier was employed using pooled cross‐sectional data. Secondly, regional stochastic frontier production functions were estimated. Lastly, the metafrontier approach was used because production environments and technologies are expected to differ between the five regions. Use of this method enabled technical efficiency scores to be corrected by the coefficient of the environment‐technology gap ratio (ETGR). Estimates of the frontier were obtained assuming a translog functional form.

Results indicate that farms differ in technical efficiencies, ETGRs and the use they make of inputs. Mean ETGRs vary substantially between farms and across regions whereas mean technical efficiencies are reasonably similar across regions but differ in the extent of variation among farms within each region. A low ETGR for the north‐western region is attributable to a lack of water resources, restricting the ability of farmers to benefit from improved varieties, and small‐sized farms, which militate against mechanization embodying labor‐saving technologies.

The results do not lead to definitive policy prescriptions. But they do provide indicators of where farm‐level research is likely to be most effective in closing the environment‐technology gap, for example by enabling farmers to take greater advantage of the productivity‐enhancing effects of improved technologies embodied in cropping machinery and irrigation facilities. The ability of farmers to alleviate the environmental constraints on wheat production is likely to vary across regions, and will depend on the nature of these constraints and the ability of researchers to design technologies suited to each region that will overcome them.
Valuing animal genetic resources: a choice modeling application to indigenous cattle in Kenya
Authors: Ruto Eric , Garrod Guy , Scarpa Riccardo
Published: August 2010

In an effort to improve productivity and profits, many farmers have replaced traditional livestock breeds with higher yielding alternatives. While such changes may bring about short‐term economic gains, the loss of traditional livestock breeds could result in the loss of an important genetic resource as a variety of important genetic traits adapted to local conditions gradually become less common in the population. This is a particular problem in Africa, where livestock make a substantial contribution to human livelihoods. Using the example of cattle in Kenya's pastoral livestock markets this study uses a choice experiment approach to investigate buyers' preferences for indigenous breeds such as the Maasai Zebu. The analysis employs a latent class approach to characterize heterogeneity in valuations both within and across respondents buying cattle for breeding, slaughter, or resale. The results show that there are at least three classes of buyers with distinct preferences for cattle traits and that most buyers favor exotic rather than indigenous breeds. Such preferences have implications for the conservation of indigenous cattle in Kenya and in other developing countries and suggest that some form of intervention may be required to ensure the preservation of this important animal genetic resource.
Valuing the influence of underlying attitudes and the demand for organic milk in Japan
Authors: Managi Shunsuke , Yamamoto Yasutaka , Iwamoto Hiroyuki , Masuda Kiyotaka
Published: August 2010

Subjective perceptions about a product affect consumer choice. Accordingly, acquiring the underlying demand characteristics that consumers find desirable is vital for firms planning future marketing strategies. However, the extent to which product‐specific perceptions affect consumer choice is poorly understood. New agricultural standards for organic livestock were introduced in Japan in November 2005 and are expected to influence the market significantly. Choice modeling (CM) is used to explore how consumers evaluate the latent demands and conventional attributes (or tangible values) of organic milk. The results suggest that latent demands, along with socioeconomic characteristics and conventional attributes, provide strong incentives for consumers to move from the purchase of conventional milk to organic milk. The analysis indicates that latent demands reflecting the safeness of organic milk, the better taste of organic milk, the image of environmental friendliness in the production process, and the image of the health and comfort of the cows are important factors that influence consumers' purchasing decisions. However, each specific factor has a corresponding conventional tangible attribute that needs to be targeted in marketing strategy.
Estimating market demand for fresh yam characteristics using contingent valuation: implications for crop breeding and production choices
Authors: Amegbeto N. Koffi , Manyong Victor M. , Coulibaly Ousmane , Asiedu Robert
Published: August 2010

This study uses the Box–Cox (BC) transformations to examine nonlinearity in price modeling and compare results from several functional specifications in hedonic price analysis of yam in Togo. Based on a sample of 6,402 observations on price and produce characteristics generated through a market experiment, it is found that the BC quadratic asymmetric specification is the most suitable function. Several characteristics are valued more than others, and prices vary across species, time, and market sites. Some residual symptoms of pest and disease damages on yam tubers reduce their market values. Tuber weight exhibits a diminishing marginal value and price per kilogram decreases above an optimum size; therefore, producers do not derive additional reward from extra‐large tubers. We conclude that, to effectively access and benefit from urban markets, producers should focus on small size, low weight, and conical shaped‐tubers, which are easy to process and meet the esthetic qualities preferred by urban consumers. The implications for research on improved variety development to reduce poverty and for crop and resource management practices are drawn.
An analysis of the impact of swine CAFOs on the value of nearby houses
Authors: Isakson Hans R. , Ecker Mark D.
Published: August 2010

The impact of 39 swine confined or concentrated animal feeding operations (CAFOs) in Black Hawk County, Iowa on 5,822 house sales is explored by introducing a new variable that more accurately captures the effects of prevailing winds, exploring potential adverse effects within concentric circles around each CAFO, managing selection bias, and incorporating spatial correlation into the error term of the empirical model. Large adverse impacts suffered by houses that are within 3 miles and directly downwind from a CAFO are found. Beyond 3 miles, CAFOs have a generally decreasing adverse impact on house prices as distance to the CAFO increases.
Fibronectin enhances viability and alters cytoskeletal functions (with effects on the phosphatidylinositol 3‐kinase pathway) in small cell lung cancer
Authors: Kijima T. , Maulin G. , Ma P. C. , Madhiwala Priya , Schaefer E. , Salgia R.
Published: August 2010

Small cell lung cancer (SCLC) is a rapidly progressive disease with ultimate poor outcome. SCLC has been shown to interact closely with the stromal and extracellular matrix (ECM) components of the diseased host. ECM consists of type I/IV collagen, laminin, vitronectin, and fibronectin (FN) among others. Herein, we investigated the behavior of a SCLC cell line (NCI‐H446) on FN‐coated surface. Over a course of 72 h, FN (10 ?g/ml) caused both increased survival and proliferation of NCI‐H446 cells. Survival under serum‐starved conditions increased 1.44‐fold and proliferation in the presence of fetal calf serum increased by 1.30‐fold. The phosphatidylinositol 3‐kinase (PI3‐K) inhibitor LY294002 reduced both survival and proliferation of NCI‐H446 cells (0.48‐ and 0.27‐fold, respectively), even on FN‐coated surface. We next determined the effects of FN on cytoskeletal function such as cell motility/morphology and adhesion. Over a course of 24 h, FN reduced aggregation of NCI‐H446 cells and induced flattened cellular morphology with neurite‐like projections after 1 h, however, in the presence of LY294002, the cells rounded up. Adhesion of NCI‐H446 cells also increased with FN (4.47‐ fold) which was abrogated with LY294002 treatment. This correlated with phosphorylation of the cytoskeletal protein p125FAK, on Tyr397, Tyr861 and Ser843 residues with FN. Even in the presence of LY294002, these serine/tyrosine residues were still phosphorylated on FN‐coated surface. In contrast, the focal adhesion protein paxillin was not phosphorylated at Tyr31 with FN. In summary, FN stimulation of SCLC cells leads to enhancement of viability and change in cytoskeletal function that are partially mediated through the PI3‐K pathway.
Effect of homocysteine on calcium mobilization and platelet function in type 2 diabetes mellitus
Authors: Alexandru N. , Jardín I. , Popov D. , Simionescu M. , García‐Estañ J. , Salido G. M. , Rosado J. A.
Published: August 2010

Type 2 diabetes mellitus induces a characteristic platelet hyperactivity that might be due to several factors including oxidativ stress and abnormal intracellular Ca2+ homeostasis. Hyperhomocysteinaemia is considered a risk factor in the development of thrombosis although its effect on platelet function and the mechanisms involved are still poorly understood. Here we show tha homocysteine induce a concentration‐dependent increase in endogenous production of reactive oxygen species (ROS), which was significantly greater in platelets from diabetic patients than in controls. Platelet treatment with homocysteine resulted in Ca2+ release from the dense tubular system and the acidic stores. Ca2+ mobilization‐induced by homocysteine consisted in two components, an initial slow increase in intracellular free Ca + concentration ([Ca +]i) and a rapid and marked increase in [Ca2+]i, th second leading to the activation of platelet aggregation. As well as ROS generation, Ca2+ mobilization and platelet aggregation were significantly greater in platelets from diabetic donors than in controls, which indicate that platelets from diabetic donors are more sensitive to homocysteine. These findings, together with the hyperhomocysteinaemia reported in diabetic patients, strongly suggest that homocysteine might be considered a risk factor in the development of cardiovascular complications associated to type 2 diabetes mellitus.
Proteins of the secretory pathway govern virus productivity during lytic gammaherpesvirus infection
Authors: Mages J. , Freimüller K. , Lang R. , Hatzopoulos A. K. , Guggemoos S. , Koszinowski U. H. , Adler H.
Published: August 2010

Background: Diseases caused by gammaherpesviruses continue to be a challenge for human health and antiviral treatment. Most of the commonly used antiviral drugs are directed against viral gene products. However, the emergence of drug‐resistant mutations ma limit the effectiveness of these drugs. Since viruses require a host cell to propagate, the search for host cell targets is an interestin alternative. Methods: In this study, we infected three different cell types (fibroblasts, endothelial precursor cells and macrophages with a murine gammaherpesvirus and analysed the host cell response for changes either common to all or unique to a particular cell type using oligonucleotide microarrays. Results: The analysis revealed a number of genes whose transcription was significantly up‐ or down‐regulated in either one or two of the cell types tested. After infection, only two genes, Lman1 (also known as ERGIC53) an synaptobrevin‐like 1 (sybl1) were significantly up‐regulated in all three cell types, suggestive for a general role for the virus life cycl independent of the cell type. Both proteins have been implicated in cellular exocytosis and transport of glycoproteins through the secre tory pathway. To test the significance of the observed up‐regulation, the functionality of these proteins was modulated, and the effect on virus replication was monitored. Inhibition of either Lman1 or sybl1 resulted in a significant reduction in virus production. Conclusions: This suggests that proteins of the secretory pathway which appear to be rate limiting for virus production may represent new targets for intervention.
Transgenic mice overexpressing human G972R IRS‐1 show impaired insulin action and insulin secretion.
Authors: Hribal Marta L. , Tornei F. , Pujol A. , Menghini R. , Barcaroli D. , Lauro D. , Amoruso R. , Lauro R. , Bosch F. , Sesti G. , Federici M.
Published: August 2010

Molecular scanning of human insulin receptor substrate (Irs) genes revealed a single lrs1 prevalent variant, a glycine to arginine change at codon 972 (G972R); previous in vitro studies had demonstrated that the presence of this variant results in an impaired activation of the insulin signalling pathway, while human studies gave controversial results regarding its role in the pathogenesis of insulin resistance and related diseases. To address in vivo impact of this IRS‐1 variant on whole body glucose homeostasis and insulin signalling, we have generated transgenic mice overexpressing it (Tg972) and evaluated insulin action in the liver, skeletal muscle and adipose tissue and assessed glucose homeostasis both under a normal diet and a high‐fat diet. We found that Tg972 mice developed age‐related glucose and insulin intolerance and hyperglycaemia, with insulin levels comparatively low. Glucose utilization and insulin signalling were impaired in all key insulin target tissues in Tg972 mice. There were no differences in pancreatic morphology between Tg972 and wild‐type mice, however when insulin secretion was evaluated in isolated islets, it was significantly reduced in Tg972 mice islets at any glucose concentration tested. Under a high‐fat diet, Tg972 mice had increased body and adipose tissue weight, and were more prone to develop diet‐induced glucose and insulin intolerance. So, we believe that Tg972 mice may represent a useful model to elucidate the interaction between genetic and environmental factors in insulin resistance pathogenesis. Furthermore, they may become an important tool to test novel tailored therapies.
Thymic stromal cells and positive selection
Authors: Chidgey Ann R. , Boyd Richard L.
Published: August 2010

The intrathymic differentiation events leading to the development and export of mature T cells tolerant to self yet capable of responding to foreign peptide antigen in the context of self‐MHC are clearly both dynamic and complex. The changing phenotype of the developing thymocyte as it migrates through and interacts with the heterogeneous thymic microenvironment and the intracellular signalling events associated with such interactions are being extensively studied, yet many aspects remain poorly defined, such as the precise relationship between stromal cells and thymic selection. Positive and negative selection are crucial events in the development of T cells, leading to a diverse yet non‐autoreactive immune system. A breakdown in either of these processes could lead to either a reduced T cell repertoire or the escape into the periphery of autoreactive T cells – both clearly having deleterious consequences for the health of the individual. This review aims to summarise the current status of research in thymic positive selection with emphasis on the role of different cell types and peptides.
Identification of the translocating bacteria in rats with acute liver injury and their relation to the bacterial flora of the intestinal mucosa
Authors: Wang Mei , Adawi Diya , Molin Göran , Pettersson Bertil , Jeppsson Bengt , Ahrne Siv
Published: August 2010

The bacterial flora of the intestine and the bacteria found in liver, mesenteric lymph nodes, portal and arterial blood after D‐galactosamine‐induced liver injury, with and without pretreatment with Lactobacillus plantarum DSM 9843, were studied in the rat. Dominating representatives were identified to species level by 16S rDNA sequencing and typed by randomly amplified polymorphic DNA (RAPD) and by restriction endonuclease analysis (REA) for strain definition. It was proven that bacterial strains from the intestine occur at extraintestinal sites after liver injury. Lactobacillus spp. dominated the intestinal flora and were also the most frequently found genus in the liver and the mesenteric lymph nodes. Some of the blood isolates, identified as Staphylococcus aureus, Proteus vulgaris and Bacteroides merdae, were not found as a dominating part of the mucosal flora. Treatment with L. plantarum before liver injury decreased translocation and made the intestinal flora increasingly dominated by lactobacilli.
Interactions between epidermal growth factor and the Tabby mutation in skin
Authors: Isaacs K. , Brown G. , Moore G. P. M.
Published: August 2010

Mutations of the X‐linked genes Tabby (Ta) in mice and EDA in humans result in developmental and functional abnormalities, primarily in the skin and hair follicles. Although both genes are believed to encode membrane‐associated proteins, it has been suggested that, in the mouse, the mutation is linked to a deficiency of epidermal growth factor (EGF). This study investigated relationships between the skin abnormalities of Ta mice and the EGF signal pathway. The distribution of endogenous EGF in tissues of Ta/Y and +/Y animals was examined and, because of its reported morphogenetic actions and ability to overcome receptor signalling defects in vivo, the effects of exogenous EGF on the hair follicle population were determined. EGF levels were similar in a number of tissues of Ta/Y and +/Y mice, but amounts in Ta/Y submaxillary glands were reduced, probably due to a smaller gland size. Exogenous EGF inhibited hair follicle development and decreased follicle density in both genotypes. It was concluded from comparisons of the distributions of EGF and its effects in skin with those in mice bearing mutations in the EGF signal pathway that the normal phenotype results from interactions between EGF and the Ta peptide in skin.
Molecular basis of a novel rhino (hrrhChr) phenotype: a nonsense mutation in the mouse hairless gene
Authors: Ahmad W. , Panteleyev A. A. , Henson‐Apollonio V. , Sundberg J. P. , Christiano A. M.
Published: August 2010

The hairless and rhino mutations are autosomal recessive allelic mutations that map to mouse Chromosome 14. In general, the rhino phenotype is a more severe manifestation of the hairless phenotype. In both hairless and rhino mice, the hair begins shedding in a cephalocaudal pattern within 7 days after birth, and never regrows due to a series of irreversible cellular events. The hairless mutation closely resembles the human disease known as papular atrichia (MIM 209500). Recently, this disease was linked to Chromosome 8p12, the human homolog of hairless was cloned and mapped to the same locus, and mutations have been identified in several different families. In order to gain insight into the pathophysiology of disease in papular atrichia, we sought to utilize mouse mutations as in vivo model systems. In this study, we report the identification of a homozygous nonsense mutation in the coding region of the hr gene in a hairless mouse captured on a chicken farm in the Midwestern United States. To reflect the place of identification of this new mutation at the hr locus, we have designated this allele hrrhChr using the laboratory code Chr (Christiano).
What controls hair follicle cycling?
Authors: Stenn K. S. , Nixon A. J. , Jahoda C. A. B. , McKay I. A. , Paus R.
Published: August 2010

Despite more than a hundred years of professinal hair research, and substantial recent progress in unravelling the molecular controls of hair follicle morphogenesis, the chronobiological control system that cyclically drives the hair follicle through dramatic remodelling processes between phases of growth (anagen), regression (catagen), and relative resting (telogen) have remained disappointingly obscure. In view of the vast literature that has become available over the past decades on numerous genetic, biochemical, cellular and pharmacological aspects of hair growth control under physiological and pathological conditions, it is astounding how comparatievely few researchers in the field have published theoretical concepts that explore how hair follicle cycling might be controlled. Since this question is at the very heart of basic and clinically applied hair biology, it deserves a much more systematic and serious public exploration, which the following contributions are designed to stimulate.
The antipruritic effect of a 5‐HT3receptor antagonist (tropisetron) is dependent on mast cell depletion – an experimental study
Authors: Weisshaar E. , Ziethen B. , Röhl F.‐W. , Gollnick H.
Published: August 2010

The background of this study is that 5‐HT3receptor antagonists are reported to have an antipruritic effect in uremic and cholestatic pruritus. Recently, we could not confirm such an effect in healthy subjects under experimental conditions. Therefore, it was the aim of the present study to further evaluate a possible antipruritic effect of a 5‐HT3receptor antagonist (tropisetron) on serotonin‐ and histamine‐induced itch before and after skin mast cell depletion in 10 healthy subjects. The results were compared to serotonin and histamine iontophoresis in non‐pretreated and pretreated skin with an orally applied antihistamine (cetirizine). Skin mast cell depletion was performed by iontophoretical application of compound 48/80. Wheals and flares were planimetrically evaluated. Itching and burning sensations were rated on an analog scale over a 24‐min period. The test protocol also comprised alloknesis, defined as induction of perifocal itch sensations by a mechanical stimulus. When serotonin was inotophoretically applied after mast cells had been depleted before, oral tropisetron resulted not only in significantly lower whealing, itching and alloknesis but also reduced flares. In contrast, after oral pretreatment with tropisetron histamine‐induced reactions before and after mast cell depletion did not significantly change. Our study demonstrates that in this model, tropisetron as a 5‐HT3receptor antagonist does not effect histamine‐induced itch but has a measurable effect in serotonin‐induced reactions when mast cells were depleted before. From these data evidence now exists why tropisetron is to some extent effective in certain types of pruritus such as uremic pruritus, known for increased histamine liberation and increased serotonin levels as well as degranulated and diffusely spread mast cells in the skin.
The human basophil – a novel target of the neuropeptide alpha‐melanocyte‐stimulating hormone
Authors: Böhm M. , Raap U. , Scholzen T. , Mertens M. , Brehler R. , Kapp A. , Luger T. A.
Published: August 2010

There is increasing evidence that the basophil does not only play an important role in acute allergic reactions but also in the pathogenesis of chronic allergic disorders. Here we show that human basophils express melanocortin receptors (MC‐Rs) and respond to alpha‐melanocyte‐stimulating hormone (alpha‐MSH) with regulation of proallergic cytokine expression and modulation of basophil activation markers. Using primers against all known MC‐R subtypes we demonstrate that the human basophil cell line KU812 expresses MC‐1R. Expression of MC‐1R on the surface of KU812 cells was confirmed by FACS analysis using an anti‐MC‐1R antibody. The MC‐1R expressed by KU812 cells was functionally active as alpha‐MSH induced intracellular cAMP in a dose‐dependent manner. Moreover, alpha‐MSH abrogated the effect of calcium ionophore A23187 on IL‐4 mRNA expression in these cells. The relevance of the above findings was corroborated by showing that MC‐1R surface expression is also detectable in basophils of leukocyte suspensions derived from whole human blood. Most interestingly, alpha‐MSH was capable of suppressing the inductive effect of fMLP on surface expression of the basophil activation marker CD63 in leukocyte suspensions of atopic individuals. Likewise, alpha‐MSH significantly blocked grass pollen‐induced up‐regulation of CD63 in leukocyte suspensions of patients with grass pollen allergy. Our findings highlight a novel functional dimension of alpha‐MSH. In addition, MSH peptides may become a novel future therapeutic avenue in treating human allergic diseases.
Melatonin metabolism in the skin
Authors: Fischer T. W. , Sweatman T. W. , Semak I. , Sayre R. M. , Wortsman J. , Slominski A.
Published: August 2010

The melatoninergic system is fully expressed in the skin, which is an effector organ of melatonin protective effects. The present study aimed at detecting melatonin metabolism in keratinocytes and to identify resulting melatonin metabolites.

Intracellular melatonin and three metabolites were detected by HPLC and LC‐MS. The metabolites were 6‐hydroxymelatonin, AFMK (N1‐acetyl‐N2‐formyl‐5‐methoxykynuramine) and 2‐hydroxymelatonin (the main intermediate between melatonin and AFMK). The intracellular concentrations were highest for melatonin, followed by 6‐hydroxymelatonin, AFMK and 2‐hydroxymelatonin. More interestingly, over a 24 h time period, melatonin consumption in favour of production of the melatonin metabolites AFMK and 2‐hydroxymelatonin was observed, whereas levels of 6‐hydroxymelatonin decreased. Finally, this process was enhanced by exposure to UVR. Thus, the cutaneous melatonin metabolism and the known biological activities of melatonin metabolites increase the spectrum of potential actions of the recently identified cutaneous melatoninergic system.
Impact of acetylcholine on sebocyte biology in vitro
Authors: Kurzen H. , Fademrecht C. , Goerdt S. , Seltmann H. , Zouboulis CH. C. , Gratchev A.
Published: August 2010

Extraneuronal acetylcholine (ACh) has been demonstrated to influence a plethora of cutaneous cell functions in an autocrine, paracrine and endocrine fashion. Previously, we could demonstrate a differentiation‐specific expression of its nicotinic (nAChR) and muscarinic receptors (mAChR) in human epidermis and its adnexal structures including sebaceous glands. Using an immortalized human sebaceous gland cell line (SZ95 sebocytes), we examined the AChR expression pattern in vitro. In proliferating and confluent SZ95 sebocytes, a wide range of AChR subunits could be detected using RT‐PCR. In particular, we detected mRNA coding for the α3, α5, α6, α7, α10, β1, β2 and β4 nAChR as well as the M1, and M3−5. The α1 and M2 and M5 subunits could only be detected in confluent SZ95 sebocytes, while in proliferating ones these subunits remained negative. The α2, α4, α9 and β3 nAChR could not be detected. Using functional assays, we assessed the impact of cholinergic agonists and antagonists on sebocyte proliferation and differentiation as evidenced by lipid production. Atropine (inhibition of all mAChR) and himbacine (inhibition of M2 and M4) potently inhibited SZ95 sebocyte proliferation in a dose‐dependent manner with a maximum effect at milimolar concentrations, while glycopyrrolate (inhibition of M1 and M3) inhibited proliferation only at high concentrations (100 µM). Interestingly also muscarine inhibited SZ95 sebocyte proliferation, however, with a maximum effect (50%) at nanomolar concentrations. The inhibitory effect of mecamylamine was less pronounced (20%). Nicotine strongly induced SZ95 sebocyte proliferation to more than 200% in a dose‐dependent manner. Lipid production was increased by nicotine and muscarine in the micromolar range. Inhibition of nAChR by mecamylamine did not significantly influence lipid production, while even nanomolar concentrations of atropine significantly increased lipid production. In conclusion, we could demonstrate highly potent effects of the cholinergic system on sebocyte proliferation and lipid production in vitro, mediated by wealth of different AChR subunits present at least at the mRNA level. In particular, promotion of sebocyte proliferation seems to be an attractive explanation for the exacerbation of sebaceous gland–related disorders like acne under the influence of chronic nicotine ingestion. In addition, seborrhea observed after treatment with anticholinergic drugs is well in line with an increase in lipid production that we found after treatment of sebocytes with atropine.