The Role of Melanocortin 1 Receptor in Cutaneous Malignant Melanoma

Cutaneous malignant melanoma (CMM) is an epidemic cancer in the United States. Survival rates for invasive CMM have not increased in past decades despite numerous clinical trials and the effective use of various combinations of chemotherapy agents to treat other cancers. Recent research has investigated the role of melanocortin 1 receptor (MC1R), a gene associated with red-hair phenotype in White individuals and with increased risk for developing CMM, in the mitogen-activated protein kinase (MAPK) pathway. This limited narrative review discusses the incidence, history, and risk factors for CMM. It explores familial CMM and provides a brief review of melanocyte development and melanogenesis. Histology of CMM and cytogenetic techniques used to identify CMM mutations is also discussed. The structure and function of MC1R is described, with particular attention to MC1R\u27s role in the MAPK pathway. Finally, the review touches on individualized therapy for CMM using genetic biomarkers and explores the promise of genomic research for finding effective treatments

Transition from sea to land: olfactory function and constraints in the terrestrial hermit crab Coenobita clypeatus

The ability to identify chemical cues in the environment is essential to most animals. Apart from marine larval stages, anomuran land hermit crabs (Coenobita) have evolved different degrees of terrestriality, and thus represent an excellent opportunity to investigate adaptations of the olfactory system needed for a successful transition from aquatic to terrestrial life. Although superb processing capacities of the central olfactory system have been indicated in Coenobita and their olfactory system evidently is functional on land, virtually nothing was known about what type of odourants are detected. Here, we used electroantennogram (EAG) recordings in Coenobita clypeatus and established the olfactory response spectrum. Interestingly, different chemical groups elicited EAG responses of opposite polarity, which also appeared for Coenobita compressus and the closely related marine hermit crab Pagurus bernhardus. Furthermore, in a two-choice bioassay with C. clypeatus, we found that water vapour was critical for natural and synthetic odourants to induce attraction or repulsion. Strikingly, also the physiological response was found much greater at higher humidity in C. clypeatus, whereas no such effect appeared in the terrestrial vinegar fly Drosophila melanogaster. In conclusion, our results reveal that the Coenobita olfactory system is restricted to a limited number of water-soluble odourants, and that high humidity is most critical for its function

Predicting cortical bone adaptation to axial loading in the mouse tibia

The development of predictive mathematical models can contribute to a deeper understanding of the specific stages of bone mechanobiology and the process by which bone adapts to mechanical forces. The objective of this work was to predict, with spatial accuracy, cortical bone adaptation to mechanical load, in order to better understand the mechanical cues that might be driving adaptation. The axial tibial loading model was used to trigger cortical bone adaptation in C57BL/6 mice and provide relevant biological and biomechanical information. A method for mapping cortical thickness in the mouse tibia diaphysis was developed, allowing for a thorough spatial description of where bone adaptation occurs. Poroelastic finite-element (FE) models were used to determine the structural response of the tibia upon axial loading and interstitial fluid velocity as the mechanical stimulus. FE models were coupled with mechanobiological governing equations, which accounted for non-static loads and assumed that bone responds instantly to local mechanical cues in an on–off manner. The presented formulation was able to simulate the areas of adaptation and accurately reproduce the distributions of cortical thickening observed in the experimental data with a statistically significant positive correlation (Kendall's τ rank coefficient τ = 0.51, p < 0.001). This work demonstrates that computational models can spatially predict cortical bone mechanoadaptation to a time variant stimulus. Such models could be used in the design of more efficient loading protocols and drug therapies that target the relevant physiological mechanisms

Fast Stochastic Cooling of Heavy Ions at the ESR Storage Ring

Since the completion of the installation of pick-up and kicker tanks in the ESR, stochastic cooling in all phase space dimensions has been demonstrated with rather short cooling times. New RF components were added. The system is now ready for experiments with secondary beams. The momentum sensitivity of the pick-up electrodes was measured. The ability of the Palmer cooling system to cool beams with a maximum momentum spread of ± 0.7 % was demonstrated. After injecting an uncooled primary argon beam from the SIS synchrotron, e-folding cooling times of 0.86 s in the longitudinal phase plane and 1.6 s in the horizontal plane were measured with 5×106 injected particles. These values are close to theoretical expectations. In a first experiment with uranium, the shortest cooling times have been below 0.5 s in both the longitudinal and vertical phase planes. The system cools the complete injected beam without beam loss. An experiment with beam accumulation following stochastic precooling was performed successfully. The resulting equilibrium phase space densities are high enough to be followed by fast electron cooling of the stack

Les charrues de la Bagoué : gestion paysanne d'une opération cotonnière en Côte d'Ivoire

Dans les années soixante-dix, les organismes internationaux prennent le relais des Etats du Tiers Monde pour soutenir et contrôler les politiques agricoles qui ont précédemment échoué. En Côte-d'Ivoire, la Banque mondiale finance un ambitieux projet de la Compagnie ivoirienne pour le Développement des Textiles (CIDT) : introduire la culture attelée, intensifier les cultures vivrières et rendre les champs permanents dans le Nord-Ouest ivoirien. Ce livre retrace les débuts (1974 à 1978) de la passionnante aventure de paysans qui, dans une région faiblement peuplée, ont élaboré des sytèmes agraires en harmonie avec l'environnement. Opérant un tri dans la panoplie technologique proposée par la CIDT, ils restent à l'affût de ce qui améliorera leur niveau de vie ou l'organisation de leur travail. Mais les nouvelles techniques contribuent à accentuer les différenciations socio-économiques; la stabilisation des cultures demeure encore une chimère, pour la CIDT comme pour les paysans, et, dans ces conditions, le bulldozer ravage les sols; la concurrence vivriers-coton n'est pas un vain mot quand c'est une société cotonnière qui se charge de promouvoir le riz et le maïs; l'installation récente des Peul et de leurs zébus chassés du Sahel par la sécheresse suscite des projets de développement contraignants, pour les éleveurs comme pour les paysans; les villes attirent les jeunes aussi... Tout bouge, la voie du développement n'est décidément pas aussi clairement tracée que le croyait la CIDT, mais la culture attelée est adoptée et la puissante volonté de progrès des paysans ne laisse pas indifférent. Quinze ans ont passé. De nouvelles études de l'ORSTOM cherchent à saisir l'évolution actuelle : l'ajustement structurel sévit ici comme ailleurs dans le Tiers Monde, les charrues sont toujours là, mais il n'y a plus l'aide de l'Etat comme dans les années soixante, plus d'aide internationale comme dans les années soixante-dix, les paysans se trouvent seuls à inventer leur avenir. (Résumé d'auteur

Stochastic Cooling at the ESR

Stochastic precooling at the ESR storage ring of GSI will be used mainly for experiments with stored radioactive fragment beams. They arrive from the fragment separator with momentum spreads and emittances for which electron cooling is too slow. The installation of components at the ESR is now complete and first commissioning experiments have been performed. Both longitudinal and transverse stochastic cooling have been demonstrated. The paper gives a short account of the system architecture, and of the response of quarter-wave plates and superelectrodes at intermediate energies. The preparation of fragment beams suitable for subsequent electron cooling is discussed for the case that a mixture of different ion species is present in the cooler ring. Results of commissioning and future prospects are presented

An accelerator mode based technique for studying quantum chaos

We experimentally demonstrate a method for selecting small regions of phase space for kicked rotor quantum chaos experiments with cold atoms. Our technique uses quantum accelerator modes to selectively accelerate atomic wavepackets with localized spatial and momentum distributions. The potential used to create the accelerator mode and subsequently realize the kicked rotor system is formed by a set of off-resonant standing wave light pulses. We also propose a method for testing whether a selected region of phase space exhibits chaotic or regular behavior using a Ramsey type separated field experiment.Comment: 5 pages, 3 figures, some modest revisions to previous version (esp. to the figures) to aid clarity; accepted for publication in Physical Review A (due out on January 1st 2003

The validity of the Landau-Zener model for output coupling of Bose condensates

We investigate the validity of the Landau-Zener model in describing the output coupling of Bose condensates from magnetic traps by a chirped radiofrequency field. The predictions of the model are compared with the numerical solutions of the Gross-Pitaevskii equation. We find a dependence on the chirp direction, and also quantify the role of gravitation.Comment: 4 pages, Late