Challenge Area Research Articles

Integrated Pest Information Platform for Extension and Education (iPiPE): Progress Through Sharing

Food security and IPM are best served by a national infrastructure of private and public professionals who routinely monitor crop health and pest incidence and then translate this knowledge to a shared platform enabling rapid dissemination of mitigation measures to limit crop loss. The Integrated Pest Information Platform for Extension and Education (iPiPE) provides such an infrastructure with cyber-age tools, information products, and expert commentary for detection and management of endemic, new, and exotic pests that threaten U.S. crops. By categorizing pests, data, and users, it enables sharing of observations while protecting the privacy of participating individuals, companies, and government agencies. The iPiPE incentivizes growers and consultants to submit observations on important pests by providing tools and information for timely management decision making. It is composed of a growing number of Crop-Pest Programs. Located across the nation and coordinated by Extension professionals, each Crop-Pest Programs addresses a variety of crops and pests while providing undergraduate students with hands-on extension and diagnostic experiences. The iPiPE was initiated in 2010, and received funding to expand as a Cooperative Agricultural Program (CAP) from the USDA AFRI Food Security Challenge Area in 2015. An important iPiPE Cooperative Agricultural Program goal is to catalyze and support a national network of similar IT platforms operated by various organizations, focused on providing information to enhance IPM and food security. An important outcome will be a national infrastructure for sharing pest observations in near real-time and for archiving them in a national depository to enable future research using geographically extensive, multiyear databases.

Fatigue life of lead-free solder thermal interface materials at varying bond line thickness in microelectronics

Microelectronics failure during operation is commonly attributed to ineffective heat management within the system. Hence, reliability of such devices becomes a challenge area. The use of lead-free solders as thermal interface materials to improve the heat conduction between a chip level device and a heat sink is becoming popular due to their promising thermal and mechanical material properties. Finite element modelling was employed in the analysis of the fatigue life of three lead-free solders (SAC105, SAC305, and SAC405) under commercial thermal cycling load (between −40°C and 85°C). This paper presents the results of the simulation work focusing on the effect of varying the solder thermal interface thickness (or bond line thickness) on the reliability of the microelectronic device. The results obtained were based on stress, strain, deformation, and plastic work density. The results showed that the fatigue life of the three solders increases as the solder thermal interface thickness increases. Also, the stresses, strains, and deformation were highest around the edges and vertices of the solder interface. In addition, the optimal solder material of choice based on the criteria of this research is given as SAC405. It has higher operational life span and good reliability capabilities.

ICook: Development of web‐based component of a 4‐H cooking intervention

A web‐based component was developed to support a cooking intervention implemented through Extension programming in 5 states. The intervention was pilot‐tested with dyads (n=61) of youth (9–10 years old) and adults. Six lessons included content on family mealtime and communication, physical activity, and goal setting. Youth received cameras and were asked to create videos on the lessons for the website which was also designed for interaction with other participants and goal setting. Based on process evaluation, 75% of youth reported making videos but only 48% reported posting videos. Barriers to posting videos included slow Internet speed at home, lack of time and forgetfulness. While 65% of youth reported intent to set goals to increase fruits, vegetables and physical activity, goal setting on the website was completed only 38 times. Youth need support built into program structure to follow through with intentions. Although Internet access has been identified as increasingly available, the barrier of slow speed Internet access, i.e., upload speed, limits posting capabilities and is important to consider when developing online interactive at‐home activities. Feedback will be used to modify online components. Funding Source: USDA/NIFA/AFRI, Integrated Proposal for Childhood Obesity Prevention Challenge Area #2012–68001‐19605 and state experiment stations.

ICook: Developing a 4‐H Curriculum for Youth and Adults

The objective was to develop a curriculum to increase culinary competence, family mealtime and physical activity of youth and adults using community‐based participatory research, integrating research and Extension through 4‐H programming. A 5‐state team adapted two existing 4‐H curricula, Fast Foods and Youth in Motion, used additional resources to address food safety, family mealtime, and MyPlate, and grounded the curriculum in the Social Cognitive Theory and experiential 4‐H learning model. The result was, iCook 4‐H, consisting of six, 2‐hour lessons and was packaged into leader and participant binders, including guides, handouts, activities and recipes for each lesson. MyPlate placemats were developed for youth with activities on the back to reinforce lesson objectives. Curriculum training webinars were held with lesson leaders and state PIs, allowing for open forum discussions prior to lessons; phone conferences occurred between lessons for process evaluation. Content and activities provided were accurate and informative but may need to be modified to increase time spent in cooking and physical activity. Findings from the pilot study will be used to further refine and revise the curriculum for the intervention phase. Funding: USDA/NIFA/AFRI, Integrated Proposal for Childhood Obesity Prevention Challenge Area #2012–68001‐19605.

ICook: Use of an online process evaluation to facilitate quality control of a 5‐State 4‐H program.

An online process evaluation tool was used to enhance quality control during a 5‐state childhood obesity prevention pilot study. Family dyads (n=61; youth aged 9–10 and their primary adult food preparer) participated in 6‐biweekly lessons to promote four priority areas (culinary skills; family meals; physical activity; food and activity goal setting). After each lesson, dyads completed online surveys, which were reviewed by researchers and lesson leaders for program improvement. Based on parent reporting on priority area goals, from earlier to later in the program, increased percentages were seen for number of biweekly family meals (82% to 88%), cooking with their children (35% to 57%) and decreased percentage for being active as a family (49% to 39%). Over the program, youth identified cooking (75%) and tasting (62%) as learning experiences compared to practicing communication at mealtime (29%). Online process evaluation facilitated researchers’ monitoring and responsiveness to multistate study implementation. Researchers were able to identify the translation of lesson priorities to the home environment and make changes for program improvement during pilot testing to improve the probability of positive intervention outcomes. Funding Source: USDA/NIFA/AFRI, Integrated Proposal for Childhood Obesity Prevention Challenge Area #2012–68001‐19605 and state experiment stations.

One-Year Outcomes After Everolimus-Eluting Stents Implantation in Ostial Lesions of Left Anterior Descending Coronary Arteries.

BackgroundIn recent years, stents are increasingly used in variety of coronary lesions. Ostial lesion of left anterior descending coronary artery (LAD) however remains a challenge area because of the invariable involvement of distal left main coronary artery (LMCA). This study was designed to evaluate the clinical and angiographic outcomes of everolimus-eluting stent (EES) implantation for ostial LAD.MethodsEESs were implanted in 45 consecutive patients with ostial LAD stenoses. For complete lesion coverage, stent positing was extended into the distal LMCA in 6 patients (13.3%) with intermediated LMCA narrowing. We assess MACE during one-year follow-up.ResultsIn-hospital success rate was 100%; neither cardiac death nor stent thrombosis in our patients, but two patients had myocardial infarction in non-related coronary artery during follow-up. Two patients had angiographic restenosis and underwent TLR. The cumulative MACE-free survival rate was 95.6% at one year.ConclusionEES was in ostial LAD lesions with complete lesion coverage achieving high procedural success rate and acceptable clinical outcomes during one-year follow-up period.

Finite Element Analysis of Elastic Stresses around Holes in Plate Subjected to Uniform Tensile Loading

The author reported stress analysis of infinite isotropic plate with a cylindrical circular hole and oblique hole. The present work deals with infinite isotropic plate under uniform tensile load. Three components of different material with different obliquity angle were used for analysis. These components having holes circular & oblique at angles 0, 30 and 60 degree are considered for study. The long twisted blades of gas turbine blade will be treated as infinite plate with oblique holes/cooling holes constituting a geometrically complex, three- dimensional body that is subjected to the action of systems centrifugal force. Stress concentration and stress field around oblique holes is a major challenge area in design of aerofoil in aerospace applications for safety because of their highly specialized applications in aerospace field under severe operating conditions. In design, Stress Concentration Factor (SCF) can be used as multiplication factor, and using that maximum stress can be predicted, thus it shows the stress field around local region. The experimental methods used are photo elastic and strain gauge techniques. When a infinite plate containing a cylindrical oblique hole is subjected to remotely applied uniform tensile load, the circumferential stresses along the boundary of the hole are produced which have been successfully used to predict stresses around holes. The resulting Stress Concentration Factor (SCF) obtained by Finite Element (FE) analysis are compared with experimentally obtained values. The results of FEA technique are in good agreement with experimental values, thus providing a means of analysing more effectively realistic Gas turbine blades. For analysis FEA software MSC/PATRAN, MSC/ NASTRAN-NX v7.0 has been used.

Modelling communication network challenges for Future Internet resilience, survivability, and disruption tolerance: a simulation-based approach

Communication networks play a vital role in our daily lives and they have become a critical infrastructure. However, networks in general, and the Internet in particular face a number of challenges to normal operation, including attacks and large-scale disasters, as well as due to mobility and the characteristics of wireless communication channels. Understanding network challenges and their impact can help us to optimise existing networks and improve the design of future networks; therefore it is imperative to have a framework and methodology to study them. In this paper, we present a framework to evaluate network dependability and performability in the face of challenges. We use a simulation-based approach to analyse the effects of perturbations to normal operation of networks. We analyse Sprint logical and physical topologies, synthetically generated topologies, and present a wireless example to demonstrate a wide spectrum of challenges. This framework can simulate challenges on logical or physical topologies with realistic node coordinates using the ns-3 discrete event simulator. The framework models failures, which can be static or dynamic that can temporally and spatially evolve. We show that the impact of network challenges depends on the duration, the number of network elements in a challenge area, and the importance of the nodes in a challenge area. We also show the differences between modelling the logical router-level and physical topologies. Finally, we discuss mitigation strategies to alleviate the impact of challenges.

Developmental timing of mRNA translation—integration of distinct regulatory elements

Targeted mRNA translation is emerging as a critical mechanism to control gene expression during developmental processes. Exciting new findings have revealed a critical role for regulatory elements within the mRNA untranslated regions to direct the timing of mRNA translation. Regulatory elements can be targeted by sequence-specific binding proteins to direct either repression or activation of mRNA translation in response to developmental signals. As new regulatory elements continue to be identified it has become clear that targeted mRNAs can contain multiple regulatory elements, directing apparently contradictory translational patterns. How is this complex regulatory input integrated? In this review, we focus on a new challenge area-how sequence-specific RNA binding proteins respond to developmental signals and functionally integrate to regulate the extent and timing of target mRNA translation. We discuss current understanding with a particular emphasis on the control of cell cycle progression that is mediated through a complex interplay of distinct mRNA regulatory elements during Xenopus oocyte maturation.

A quantitative method for measuring nanocomposite dispersion

The materials science community has identified nanoparticle dispersion as a primary challenge area for the advancement of polymer nanocomposites technology. Although nanoparticle dispersion can significantly impact important engineering properties, it is not itself a quantifiable property; qualitative TEM image assessments remain as the ‘gold standard’ for dispersion characterization. While numerous quantitative dispersion analyses have been proposed, they have often proven cumbersome, system specific and unreflective of the proposed benefits of nanoparticle reinforcement. No single quantitative method has been adopted by the community to date and inferences about processing and dispersion effects generally require subjective analysis. This paper presents a quantitative dispersion characterization method which 1) makes use of standard TEM dispersion images; 2) directly reflects proposed nanoscale reinforcement mechanisms; 3) outputs a single performance metric. By quantitatively isolating dispersion effects, this technique may help to link disparate studies in the literature while providing defensible quantitative insights into nanoscale reinforcement mechanisms.

A verified compiler for an impure functional language

We present a verified compiler to an idealized assembly language from a small, untyped functional language with mutable references and exceptions. The compiler is programmed in the Coq proof assistant and has a proof of total correctness with respect to big-step operational semantics for the source and target languages. Compilation is staged and includes standard phases like translation to continuation-passing style and closure conversion, as well as a common subexpression elimination optimization. In this work, our focus has been on discovering and using techniques that make our proofs easy to engineer and maintain. While most programming language work with proof assistants uses very manual proof styles, all of our proofs are implemented as adaptive programs in Coq's tactic language, making it possible to reuse proofs unchanged as new language features are added. In this paper, we focus especially on phases of compilation that rearrange the structure of syntax with nested variable binders. That aspect has been a key challenge area in past compiler verification projects, with much more effort expended in the statement and proof of binder-related lemmas than is found in standard pencil-and-paper proofs. We show how to exploit the representation technique of parametric higher-order abstract syntax to avoid the need to prove any of the usual lemmas about binder manipulation, often leading to proofs that are actually shorter than their pencil-and-paper analogues. Our strategy is based on a new approach to encoding operational semantics which delegates all concerns about substitution to the meta language, without using features incompatible with general-purpose type theories like Coq's logic.

The Cultural Geography Model: Evaluating the Impact of Tactical Operational Outcomes on a Civilian Population in an Irregular Warfare Environment

The civilian population has been described as ‘the center of gravity in irregular warfare’. Understanding the behavioral response of the civilian population in irregular warfare operations presents a major challenge area to the joint modeling and simulation community where there is a clear need for the development of models, methods, and tools to address civilian behavior response. This paper provides a conceptual and theoretical overview of the Cultural Geography (CG) model, a government-owned, open-source agent-based model designed to address the behavioral response of civilian populations in conflict environments. With an embedded case study, we describe the development of cognitive modules to represent the civilian population and their implementation as Bayesian belief networks (BBNs), the social structure module implemented using homophily, the process of adjudicating the effects of tactical level outcomes on a population segment within the model, and a sample case study analysis using a designed experiment.

무인전투차량 기술개발 동향조사 및 분석

지상무인 전투체계에서 요구되는 원천, 핵심기술은 해외 선진 국가들과의 치열한 경쟁이 예상된다. 따라서 주요 국가의 무인체계 기술개발현황을 분석하였으며, 분석 대상은 1998년부터 2008년까지 미국, 일본, 유럽, 캐나다, 이스라엘 등에 출원된 현황을 기준하였다. 주요 선진국의 특허맵과 전문가 의견을 수렴하여 국가별 기술 수준, 역점분야와 공백기술, 시장력 등을 분석하였으며, 앞으로 발전 가능성이 예상되는 기술과 우리나라가 중점 개발하여야할 분야 등을 제시하였다. The keen global competition is expected among foreign advanced nations for source, key technologies required by unmanned combat ground vehicle. Therefore, the trend of technologies for unmanned ground combat vehicle was analyzed in this research. It was based on the submitted patents from 1988 to 2008 in Korea, U.S.A, Japan, Europe, Canada and Israel. This analysis was focused on finding the technical level, the challenge area and breakthrough technologies and the growth of technologies of each nations considering opinions of experts. This report suggested the field of key technology development

Studies on the Fungi Associated with Soft Rot of Carrot ( Daucus Carota ) in Ilorin, North Central Nigeria

A study was carried out on the fungi associated spoilage of carrot in Ilorin, north central Nigeria. Carrot samples were collected from five locations in the city, namely; Ipata market, Challenge area, Adewole Estate, Sango, Kwara Hotel area and Sawmill. These were subjected to conventional fungal isolation procedures. Altogether, six different fungi were isolated and included were Aspergillus niger, Mucor racemosus, Penicillium italicum, Rhizoctonia solani, Fusarium sp . and Alternaria sp . The most frequently occurring isolate was M. racemosus (58%) followed by A. niger , (45%) and P. italicum (38%). Carrot samples from the Ipata market were the most infested and yielded all types of the six fungi isolated. Artificial inoculations of healthy carrot roots singly with each of the isolates revealed that only P. italicum and Alternaria sp . caused rot in artificially inoculated carrot under the conditions of this study. Keywords : Carrot, fungi, soft rot, spoilage, Nigeria

Response of four indigenous cattle breeds to natural tsetse and trypanosomosis challenge in the Ghibe valley of Ethiopia

A comparative study on the response of four indigenous cattle breeds of Ethiopia, namely Abigar, Horro, Sheko and Gurage, to natural challenge of trypanosomosis in the Tolley–Gullele area of the Ghibe valley has been undertaken from August 2000 until August 2004. Fifty female yearlings each of Horro, Sheko and Abigar and 31 of the Gurage were purchased from their natural habitats and introduced in to medium to high tsetse–trypanosomosis challenge area of the Ghibe valley. While the natural habitats of first three breeds are naturally infested with tsetse flies and trypanosomosis, that of the Gurage is known to be very minimal, if any, and hence the Gurage breed was used in this study as the known susceptible breed. During the study animal health, production performance and tsetse fly situation were monitored monthly. The Sheko breed has manifested very significantly ( p < 0.001) high overall average packed cell volume (PCV) values (25%) compared to that of Abigar (24%), Horro (23%) and Gurage (22%). It also had the lowest mean trypanosome prevalence rate of 9% against 23% of Horro, 26% of Abigar and 27% of Gurage, and the least number of Berenil ® treatments (1.36) compared to Abigar (4.0), Horro (4.6) and Gurage (6.7). While the Abigar manifested high sensitivity and frequent death to PCV depression, the Horro showed strong resilience to PCV depression and better response to Berenil ® treatment assistance. At this stage the Sheko breed was also found to be equal to the other breeds in its reproductive performance. These results need to be substantiated with further in-depth investigation including immune response, animal behavior and environmental influences.

Inducing Subacute Ruminal Acidosis in Lactating Dairy Cows

Data from experiments in which subacute ruminal acidosis (SARA) was induced in lactating dairy cows (days in milk = 154±118) were evaluated to investigate the effectiveness of the induction protocol and its effect on production outcomes. For 13 cows in 3 trials, ruminal pH was measured continuously and recorded each minute; dry matter intake and milk yield were recorded daily. Milk composition data were obtained from 9 cows in 2 of these trials. The SARA induction protocol included 4 separate periods: 4 d of baseline [normal total mixed ration (TMR)], 1 d of 50% restricted feeding, 1 or 2 d of challenge feeding [addition of 3.5 or 4.6kg of wheat-barley pellet (dry matter basis) to normal TMR], and 2 d of recovery measurements when feeding normal TMR. The SARA induction protocol lowered mean ruminal pH from 6.31 during the baseline period to 5.85 during the challenge period; pH remained below baseline level during the recovery period (6.16). Mean ruminal pH was highest (6.59) during the day of restricted feeding. Nadir ruminal pH decreased from baseline to challenge period (5.76 vs. 5.13). Hours below pH 5.6 increased from 1.10 to 8.26/d from baseline to challenge period and area below 5.6 (pH×min/d) increased from 15.0 to 190.3. Dry matter intake was not affected by SARA induction. Milk yield dropped from 35.2kg/d during baseline to 31.7 k/d during the challenge period and did not return to baseline level during the recovery period (31.3kg/d). No depression in milk fat percentage was observed when SARA was induced. Yield of fat was highest during the restricted feeding period (1.47kg/d) and was lower during the recovery period than during the baseline period (1.12 vs. 1.31kg/d). The protocol successfully induced SARA (low ruminal pH without signs of acute ruminal acidosis) on the challenge day. Milk yield was substantially reduced and did not recover within 2 d after the challenge.

ADVANCES IN ECOLOGICAL STUDIES ON LEAF LIFESPAN AND ASSOCIATED LEAF TRAITS

It is well known that plants with long leaf lifespans are found to grow mostly in habitats where nutrient availability is low and/or water is limited, while plants with short leaf lifespans usually occur on sites with relatively h igh nutrient availability. Considerable research conducted worldwide indicates t hat leaf mass-based nitrogen concentrations (N mass ) are positively rel ated to ma ximum photosynthetic rates, and specific leaf area (leaf area per unit dry weigh t) shows a negative relationship with leaf construction cost, and both decrease with increased leaf lifespan. These relationships among leaf traits generally ex ist across wide ranges of plant populations, communities and biomes, apparently reflecting convergent adaptation of plants to the given climate and/or other env ironmental constraints. Therefore, knowledge about leaf traits is important t o further understand the structure and function of plant ecosystems. With increasing altitude, leaf lifespan generally increases. Associated leaf tra its also show general altitudinal trends: leaf area-based nitrogen concentration s and maximum photosynthetic rates both increase, whereas specific leaf area dec reases with increasing elevation. Plants with long leaf lifespans are thought to be adapted to environmental stresses, such as low temperatures, short growing s e ason length or low light and nutrient availability, while those with short leaf lifespans tend to be associated with fast rates of relative growth and carbon fi xation in response to seasonal stresses of drought and/or cold winters. Under gi ven environmental constraints, the cost-benefit hypothesis explains that variati ons in leaf lifespan are controlled by the trade-offs between leaf carbon costs and benefits for maximizing carbon gain of plants. Cost-benefit simulations nice ly predict a global bimodal distribution of evergreen forests. Accordingly, leaf lifespan and its related leaf traits appear to provide a conceptual link betwee n processes at short-term leaf scales and long-term whole plant and stand-level scales. Knowledge about patterns of leaf lifespan and associated leaf traits acr oss biomes would help us to develop a processing link between biogeography model s and biogeochemistry models and to further understand mechanisms of vegetation dynamics in response to global change. However, there is limited knowledge on ho w leaf characteristics might be used to deduct ecosystem function information and how this scaling task could be accomplished. The traditional focus of plant ecophysiology, understanding how plants cope with often-stressful habitats, is organism centered. It is still difficult to quantitatively describe the relati onships among community characteristics, climatic factors and leaf characteristi cs due to a lack of field data at the ecosystem level. In China, there has been very little work on the ecology of leaf lifespan and its related traits, so it's a challenge and fruitful area for the future research.

Butterbur, a herbal remedy, protects against allergen-sensitized mast cell priming in seasonal allergic rhinitis

2 Butterbur, a Herbal Remedy, Protects Against Allergen-Sensitized Mast Cell Priming in Seasonal Allergic Rhinitis I. J. Carstairs 1, D. K. C. Lee 2, K. Haggart 2, C. M. Jackson 2, G. E Currie 2, B. J. Lipworth2; IAsthma and Allergy Research Group, Dundee, UNITED KINGDOM, 2Asthma and Allergy Research Group, Ninewells Hospital and Medical School, UNITED KINGDOM. BACKGROUND: Butterbur (BB) or Petasites hybridus, an herbal remedy, exhibits in vitro inhibition of cysteinyl leukotrienes biosynthesis and has been shown to be as effective as Hi-antihistamines on symptomatic control in seasonal allergic rhinitis (SAR). However, no placebo controlled studies have been performed to evaluate the effectiveness of BB on objective outcomes in SAR. METHODS: 20 patients with grass pollen sensitized SAR were randomized in double blind, cross over fashion to receive for 2 weeks either BB 50 mg twice daily or placebo (PL) twice daily during the grass pollen season. Nasal adenosine monophosphate (AMP) challenge (the primary outcome) was administered as a single 400 mg/ml dose after each randomized treatment, in order to evaluate in vivo allergen sensitized mast cell priming. RESULTS: Spontaneous recovery following AMP challenge (area under the response time profile curve as % 9 min) was significantly attenuated (p=0.028) with BB (584 __ 289) compared to PL (1438 _+ 240); mean difference: 854 (95% CI 95-1614), and lhe maximum % PNIF fall from baseline following AMP challenge was significantly blunted (p=0.036) with BB (30 _+ 4) compared to PL (43 + 5); mean difference: 13 (95% CI 1-25). SUMMARY: BB exhibited protection against allergen sensitized mast cell priming which may explain its clinical efficacy in patients with SAR. Funding: Universi~ of Dundee 3 Large Particle Nebulized Saline Therapy for Chronic Nasal Obstruction: A Prospective Evaluation

Susceptibility to trypanosomosis of three Bos indicus cattle breeds in areas of differing tsetse fly challenge

Studies to assess the differences in susceptibility to trypanosomosis among Bos indicus cattle breeds (Maasai Zebu, Orma Boran and Galana Boran) were conducted under conditions of varying tsetse fly challenge at the Nguruman escarpment in south-western Kenya, for a period of 1 year. It was found that under tsetse challenge quantified as high, Maasai Zebu and Orma Boran were less susceptible than Galana Boran to trypanosome infections, as judged by the significantly lower incidence of infection, development of less severe anaemia, fewer requirements for trypanocidal drug treatments, higher growth rates and fewer mortalities. In the area where tsetse challenge was considered low as a result of a tsetse fly control operation using odour-baited traps, only the Maasai Zebu and Orma Boran were compared. No significant differences in the incidence of infection, degree of anaemia or growth rates were observed between the two breeds, but all were significantly different from their counterparts in the high tsetse challenge area. These results suggest that there is variation in resistance to trypanosomosis among Bos indicus cattle breeds that could be exploited as part of the integrated trypanosomosis control programmes in East Africa.

Tumor necrosis factor-alpha in sera of obese patients: fall with weight loss.

In view of the recent demonstration that obesity in animals and humans is associated with an increase in tumor necrosis factor-alpha (TNFalpha) expression, that this expression falls with weight loss, and that TNFalpha may specifically inhibit insulin action, the possibility that TNFalpha may be a mediator of insulin resistance has been raised. We have undertaken this study to investigate whether serum TNFalpha concentrations are elevated in obese subjects, whether they fall after weight loss, and whether this fall parallels the fall in insulin release after glucose challenge. Obese patients (age range: 25-54, weight mean +/- SD: 96.4 +/- 13.8 kg, body mass index: 35.7 +/- 5.6 kg/m2) were started on a diet program. The mean weight fell to 84.5 +/- 11.3 (P < 0.0001) and body mass index to 31.3 +/- 4.9 (P < 0.0001). Plasma TNFalpha concentrations were markedly elevated in the obese (3.45 +/- 0.16 pg/mL), when compared with controls (0.72 +/- 0.28 pg/mL), and fell significantly (2.63 +/- 1.40 pg/mL) after weight loss (P < 0.02). The magnitude of insulin release after glucose (75 g) challenge (area under the curve) also fell significantly (P < 0.01) after weight loss. The magnitude of weight loss and fall in TNFalpha were related to basal body weight (r = 0.57, P < 0.001) and basal TNFalpha (r = 0.55, P < 0.001) concentrations, respectively, but not to each other or to the glucose-induced insulin release (area under the curve). We conclude that obesity is associated with increased plasma TNFalpha concentrations, which fall with weight loss. Because circulating TNFalpha may mediate insulin resistance in the obese, a fall in TNFalpha concentrations may contribute to the restoration of insulin resistance after weight loss, Thus, TNFalpha may be an important circulating cytokine, which may provide a potentially reversible mechanism for mediating insulin resistance.