Phonotactic influences on short-term memory

The impact of phonotactic probabilities on serial recall was investigated in a series of experiments. In Experiments 1A and 1B, 7 and 8 year olds were tested on their serial recall of monosyllabic words and of nonwords varying in phonotactic frequencies. A recall advantage to words over nonwords remained when stimuli were balanced for phonotactic probability, but nonword recall showed superior accuracy for high over low probability nonwords, as in Experiment 2. The nonword frequency effect appears to reflect the frequency of constituent syllables rather than biphones. Both lexicality and high phonotactic frequency led to increased proportions of full over partial recall of the memory stimuli. These findings indicate that decayed memory traces in phonological short-term memory can be reconstructed using either lexical or phonotactic knowledge.     

Folding mechanism of the alpha-subunit of tryptophan synthase, an alpha/beta barrel protein: global analysis highlights the interconversion of multiple native, intermediate, and unfolded forms through parallel channels

A variety of techniques have been used to investigate the urea-induced kinetic folding mechanism of the alpha-subunit of tryptophan synthase from Escherichia coli. A distinctive property of this 29 kDa alpha/beta barrel protein is the presence of two stable equilibrium intermediates, populated at approximately 3 and 5 M urea. The refolding process displays multiple kinetic phases whose lifetimes span the submillisecond to greater than 100 s time scale; unfolding studies yield two relaxation times on the order of 10-100 s. In an effort to understand the populations and structural properties of both the stable and transient intermediates, stopped-flow, manual-mixing, and equilibrium circular dichroism data were globally fit to various kinetic models. Refolding and unfolding experiments from various initial urea concentrations as well as forward and reverse double-jump experiments were critical for model discrimination. The simplest kinetic model that is consistent with all of the available data involves four slowly interconverting unfolded forms that collapse within 5 ms to a marginally stable intermediate with significant secondary structure. This early intermediate is an off-pathway species that must unfold to populate a set of four on-pathway intermediates that correspond to the 3 M urea equilibrium intermediate. Reequilibrations among these conformers act as rate-limiting steps in folding for a majority of the population. A fraction of the native conformation appears in less than 1 s at 25 degrees C, demonstrating that even large proteins can rapidly traverse a complex energy surface.     

Thyrotoxicosis. Recognition and management

Thyrotoxicosis is a common endocrine problem encountered in the primary care setting. It can exist in the presence or absence of thyroid disease and is associated with a wide range of causes, including primary hyperthyroidism, thyroid inflammation, and ingestion of exogenous thyroid hormone preparations. presenting complaints and clinical manifestations of this disorder can vary greatly, creating a challenge for the primary care provider. Recognition of clinical signs and symptoms and selection of appropriate laboratory studies can establish the diagnosis promptly. Once the diagnosis is identified, various effective and appropriate treatment options are available. It is important to distinguish between those problems that require subspecialty referral and those that can be treated by primary care providers. Many of the syndromes associated with thyrotoxicosis can be managed in the primary care setting. Interventions include patient counselling, patient education, judicious use of appropriate medications, and careful follow-up.     

Cerebral arteriovenous malformations in children: neuroimaging findings

Cerebral arteriovenous malformations (CAVMs) are uncommon in children. CAVMs represent the most frequent intracranial vascular pathology at pediatric ages. This report concerns 13 children below the age of 16; all were identified between September 1995 and December 1996 with 14 CAVMs among them. All were proved by conventional cerebral angiography (CCA). Thirteen computed tomography (CT), 7 magnetic resonance images (MRI), 2 magnetic resonance angiography (MRA) and 13 conventional cerebral angiography (CCA) were analyzed. Most CAVMs nidus were located in cerebral hemispheres. Four in the temporal lobe, two in the parietal lobe, three in the frontal lobe, two in the occipital lobe, and three in the corpus callosum. One of them was of a mixed type with two nidi. The major clinical features of CAVMs were intracranial hemorrhage and seizures. Experience here was that MRI is superior to CT in showing the exact anatomic relationships of the nidus and in demonstrating the extent of CAVMs nidus obliteration after treatment. MRA provided a noninvasive means of studying blood vessels and vascular pathology in relationship to the CAVMs nidus. Standard angiography is still necessary to characterize in-flow and out-flow of vessels in CAVMs when definitive treatment is considered.     

Inhibition of proliferation and expression of T-antigen in SV40 large T-antigen gene-induced immortalized cells following transplantations

In this paper the Authors reviewed the recent literature for a more comprehensive and clear vision of the epidemiological and pathological aspects of retroperitoneal sarcomas. The most effective procedures for a an early and accurate diagnosis were identified. Moreover, the different therapeutic choices were taken into account focusing on those provided of the major potential in terms of oncologically valid treatment.     

Attenuation of neutrophil and endothelial activation by intravenous morphine in patients with acute myocardial infarction

To investigate the effects of morphine on neutrophil and endothelial activation, we measured serum levels of intercellular adhesion molecule-1 (ICAM-1), L-selectin, and neutrophil endopeptidase 24.11 (NEP) in 38 patients with acute myocardial infarction (group 1) and 16 control subjects (group 2). In group 1, all the patients underwent blood sampling at initial presentation and 10 minutes later. Twenty of them had 3 mg of morphine administered intravenously immediately after the first sampling (group 1A) and the other 18 after a second sampling (group 1B). The serum levels of ICAM-1 and L-selectin were both significantly higher in groups 1A and 1B than in group 2. In group 1A, the ICAM-1 decreased significantly at second blood samplings (310 +/- 28 vs 368 +/- 30 ng/ml; p <0.001), whereas in group 1B there was no significant change in ICAM-1 (357 +/- 33 vs 359 +/- 26 ng/ml; p = NS). In group 1A, the L-selectin decreased significantly at second blood samplings (2.3 +/- 1.2 mg/L, p <0.001 vs baseline), whereas in group 1B there was no significant change in L-selectin (3.9 +/- 1.0 mg/L, p = NS vs baseline). There was no significant difference in baseline NEP activities between groups 1A and 1B (4.89 +/- 1.22 vs 5.14 +/- 1.57 nmol/mg protein; p = NS). However, the NEP activities at second blood samplings decreased significantly in group 1A (9.88 +/- 1.86 nmol/mg protein, p <0.001 vs baseline), whereas no significant changes were observed in group 1B (5.09 +/- 1.62 nmol/mg protein, p = NS vs baseline). In conclusion, morphine increased NEP activities and thus attenuated shedding of L-selectin and ICAM-1.