Destabilization of tracts of simple repetitive DNA in yeast by mutations affecting DNA mismatch repair

The genomes of all eukaryotes contain tracts of DNA in which a single base or a small number of bases is repeated. Expansions of such tracts have been associated with several human disorders including the fragile X syndrome. In addition, simple repeats are unstable in certain forms of colorectal cancer, suggesting a defect in DNA replication or repair. We show here that mutations in any three yeast genes involved in DNA mismatch repair (PMS1, MLH1 and MSH2) lead to 100- to 700-fold increases in tract instability, whereas mutations that eliminate the proof-reading function of DNA polymerases have little effect. The meiotic stability of the tracts is similar to the mitotic stability. These results suggest that tract instability is associated with DNA polymerases slipping during replication, and that some types of colorectal cancer may reflect mutations in genes involved in DNA mismatch repair.     

Characterization of a surface metalloprotease from Herpetomonas samuelpessoai and comparison with Leishmania major promastigote surface protease

It has been suggested that the thymic polypeptide thymopoietin interacts with skeletal muscle nicotinic acetylcholine receptors (nAChRs) and brain nicotinic receptors labeled by alpha-bungarotoxin (alpha-BuTX). In this study, the effects of neonatal thymectomy on the density of skeletal muscle nAChRs and the density of brain alpha-BuTX binding sites at 7 and 45 days postnatal were investigated. In addition, the densities of receptors in the skeletal muscle and brain of the athymic nu/nu mouse at 42 days postnatal were measured. We found little evidence that the absence of the thymus alters the density of nicotinic receptors in either skeletal muscle or brain.     

Skin testing after anaphylactoid reactions to dental local anesthetics. A comparison with controls

Reactions to scratch and intradermal challenge with a variety of local anesthetics were examined in 90 patients and compared with 45 controls. The frequency of a positive scratch test was 13 of 90 in the patient group and 12 of 45 in the control group. Thus scratch testing did not appear to discriminate between test and control groups. Significantly greater numbers of patients (22 of 90) gave a positive intradermal response than controls (4 of 45) (chi-squared test p < 0.05). Nine patients showed reactions to more than one agent. The majority of reactions in both patients and controls were in atopic subjects (chi-squared test p < 0.05). In 87 of the 90 patients with suspected anaphylactoid reactions to local anesthetic agents, negative skin reactions to at least one of the agents allowed intrabuccal challenge and subsequent recommendation of an agent for future use. Skin testing, though not providing formal proof of allergy, provides a useful test to indicate local anesthetics that may be used for future procedures.     

Operative creation of left to right cardiac shunts: pulmonary functional sequelae

The tuberomammillary nucleus, a cluster of cells in the posterior hypothalamus, is the only known source of brain histamine. Although this nucleus is well described in terms of anatomy and neurochemistry, only little is known about its function. In the present study, the effect of a lesion in the region of this nucleus on intracranial self-stimulation was examined. Rats were implanted bilaterally with stimulating electrodes in the lateral hypothalamus and unilaterally with one lesion electrode in the region of this nucleus. After three days of baseline testing, half of the animals were given an electrolytic lesion. The animals were retested for six consecutive days, and thereafter weekly for another seven weeks. From the second day postlesion on, we unexpectedly found a gradual increase in response rate, which peaked on day 13 in the ipsilateral hemisphere only. Although there was no further increase over subsequent days, response rates remained elevated during the following seven weekly tests. The observed increase in lateral hypothalamic self-stimulation after an electrolytic lesion of the tuberomammillary nucleus is discussed in terms of an inhibitory system, possibly located in the region of this nucleus which, when removed by the lesion, increased reinforcing effects of the electrical brain stimulation. The fact that the effects on self-stimulation were lateralized to one hemisphere rules out an interpretation in terms of unspecific "performance" variables that could influence rate of lever pressing.     

Nonlinear Galerkin methods for a system of PDEs with Turing instabilities

We address and discuss the application of nonlinear Galerkin methods for the model reduction and numerical solution of partial differential equations (PDE) with Turing instabilities in comparison with standard (linear) Galerkin methods. The model considered is a system of PDEs modelling the pattern formation in vegetation dynamics. In particular, by constructing the approximate inertial manifold on the basis of the spectral decomposition of the solution, we implement the so-called Euler–Galerkin method and we compare its efficiency and accuracy versus the linear Galerkin methods. We compare the efficiency of the methods by (a) the accuracy of the computed bifurcation points, and, (b) by the computation of the Hausdorff distance between the limit sets obtained by the Galerkin methods and the ones obtained with a reference finite difference scheme. The efficiency with respect to the required CPU time is also accessed. For our illustrations we used three different ODE time integrators, from the Matlab ODE suite. Our results indicate that the performance of the Euler–Galerkin method is superior compared to the linear Galerkin method when either explicit or linearly implicit time integration scheme are adopted. For the particular problem considered, we found that the dimension of approximate inertial manifold is strongly affected by the lenght of the spatial domain. Indeeed, we show that the number of modes required to accurately describe the long time Turing pattern forming solutions increases as the domain increases.     

Recommendation in museums: paths,sequences, and group satisfaction maximization

Multimedia Tools and Applications - This work addresses the problem of generating and then recommending an artworks sequence for a group of visitors within a museum. Differently from a recommender...     

A posteriori error estimates in finite element solution of structure vibration problems with applications to acoustical fluid-structure analysis

We present an a posteriori error estimator for piecewise linear finite element approximations of structure vibration problems. We prove that this estimator is equivalent to the energy norm of the error. Also, we introduce an adaptive mesh-refinement procedure based on the proposed estimator to analize fluid-structure interaction problems. Finally, numerical results for some test examples are presented which show the efficiency of the error estimator and the mesh-refinement techniques.