Recognition by familiarity is preserved in Parkinson's without dementia and Lewy-Body disease.

Objective: The retrieval deficit hypothesis states that the lack of deficit in recognition often observed in patients with Parkinson's disease is because of the low retrieval requirements of the task, given that these patients have retrieval and not encoding deficits. To test this hypothesis we investigated recognition memory by familiarity in Parkinson's patients and in patients with Lewy Bodies disease and Parkinson with dementia. Method: We analyzed to what extent the experimental groups were able to recognize by familiarity in a typical yes/no recognition memory task. The experimental groups were patients with early nondemented Parkinson's disease, advanced nondemented Parkinson's disease, demented Parkinson's patients, and patients with dementia with Lewy Bodies. We compared their performance with a group of young and another group of old healthy participants. The estimation of familiarity was made by analyzing recognition of word targets and distractors consisting of combinations of different letters in comparison with a condition in which targets and distractors were composed of similar letters, even though subjects were unaware of the independent variable. Results: The results indicate that familiarity was used at the same level by controls, patients with early Parkinson's disease and patients with dementia with Lewy Bodies. Although late Parkinson patients also used familiarity, its effect was only marginally significant. Patients with Parkinson's disease and dementia were not capable of using familiarity in recognition memory. Conclusions: Our results support the retrieval deficit hypothesis as Parkinson's patients without dementia show no deficit in a situation in which the retrieval requirements are minimal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is It Worth Refining Linear Approximations to Non-Linear Rational Expectations Models?

We characterize the balanced growth path of the basic neoclassical growth economy using standard numerical solution methods which solve a linear or log-linear approximation to the economic model, as well as methods which preserve the nonlinearity in the original model. We also apply the same methods adding indivisible labor to the basic model, and to a monetary version of that economy, subject to a cash-in-advance constraint. In a unified framework, we show that log-linear approximations should generally be preferred to linear approximations. We also provide evidence that preserving the original nonlinear structure of the model when computing the numerical solution generally yields minor gains in accuracy. Methods that use either a linear or a log-linear approximation to the model can produce solutions as accurate as the parameterized expectations method. However, in extreme parametric cases, the solution may be rather sensible to small numerical errors, and even a log-linear approximation may then be inappropriate. Methods using the nonlinear structure of the original model can then perform significantly better.     

Proadrenomedullin N-terminal 20 peptide inhibits aldosterone secretion of human adrenocortical and Conn''s adenoma cells: comparison with adrenomedullin effect

Hepatocyte growth factor (HGF) is normally expressed by mesenchymal cells while its receptor, c-Met, is expressed in epithelial cells. Since HGF is critically involved in epithelial-mesenchyme interactions and the retinal pigment epithelium (RPE) is present at the interface between the retina and choroid, this study was initiated to determine whether the RPE expresses or responds to HGF in vitro. Cultured adult and fetal human RPE expressed mRNA for HGF and c-Met by RT-PCR. ELISA assay demonstrated the secretion of HGF into RPE culture supernatants. Tyrosine phosphorylation of c-Met was constitutively found in 72 hour RPE cultures and could be rapidly induced in serum-starved cells by concentrated RPE supernatants. HGF was mitogenic for cultured RPE (100 ng/ml.) and stimulated their chemotaxis (maximal response at 50 ng/ml). RPE are one of only a very limited number of epithelia that express both HGF and its receptor, suggesting the possibility of an autocrine action for this growth factor.     

Cyst of the medial meniscus: observation of two cases

The authors report two cases of cyst of the medial meniscus. In both cases imaging diagnostics, CT scan, or MRI allowed us to reveal the characteristic horizontal meniscal lesion that would be the primary cause of cystic degeneration of the meniscus. The two cases were treated by selective resection of the meniscal lesion and arthroscopic decompression of the cyst.     

Solution spinning of a semirigid chain polymer forming ultrahigh modulus fibers

Single filaments of the polyterephthalamide of p-aminobenzylhydrazide (X-500) were prepared by spinning X-500 solutions in dimethyl sulfoxide (DMSO) using water as a coagulating agent. The polymer is known for its ability to develop ultrahigh modulus fibers and for having a semirigid chain conformation with a persistence length of ～50 Å in DMSO. In the latter solvent, molecular rigidity appears to be just below that required for spontaneous formation of a nematic phase. The orientation of the fibers was performed in three different stages: during coagulation (I), in the washing bath following coagulation (II), and during postspinning treatments (III). Corresponding mechanical properties were determined. The results indicate that high elastic modulus (15 GPa) already appears during step I at very moderate pulloff ratios. Therefore, considerable orientation had already occurred in the flowing solution. Further increase of fiber orientation yields a large increase of modulus (from 22 to 67 GPa) during solid-state deformation (step III). The orientation of the flowing solution was monitored by viscosity and birefringence measurements. The results are discussed in terms of orientation due to elongational and shear flow and, possibly, a flow-induced transition to a nematic phase in the concentrated solution in which chain entanglement is shown to occur.     

Ingestion of high doses of fish oil increases the susceptibility of cellular membranes to the induction of oxidative stress

Feeding rats with 4 g/kg body weight of sardine oil during 7 or 14 days increases the content of eicosapentaenoic acid and docosahexanoic acid in the erythrocyte and hepatic microsomal membranes by 2 to 6%. These membranes show increased susceptibility to the induction of oxidative stress, expressed as lipid peroxidation, when they are exposed to Fe²⁺-ascorbate and to NADPH-Fe³⁺-ADP, respectively. The results indicate that in order to prevent the increased susceptibility to lipid peroxidation, supplementation with larger amounts of antioxidants may be needed than those required to stabilize the oil.     

Effects of age and ability on syllogistic reasoning in early adolescence.

Assessed the influence of age and ability on linear syllogistic reasoning in early adolescence by presenting 109 11- and 13-yr-old Ss of 2 levels of ability (bright and average assessed by the Iowa Test of Basic Skills) with 64 3-term series problems (e.g., "If John is better than Bill, and Bill is better than Tom, then who is the best?"). The effect of ability was quite dramatic even with verbal grade equivalent and Raven's Standard Progressive Matrices scores as covariates, whereas the effect of age was marginally significant and confounded with both. Comparison to H. H. Clark's (1969) adult sample showed that the pattern of errors was essentially similar for adolescents and adults, but more similar for the average than the bright Ss. Implications for a theory of intellectual precocity are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)