Aggregation and motor neuron toxicity of an ALS-linked SOD1 mutant independent from wild-type SOD1

Analysis of transgenic mice expressing familial amyotrophic lateral sclerosis (ALS)-linked mutations in the enzyme superoxide dismutase (SOD1) have shown that motor neuron death arises from a mutant-mediated toxic property or properties. In testing the disease mechanism, both elimination and elevation of wild-type SOD1 were found to have no effect on mutant-mediated disease, which demonstrates that the use of SOD mimetics is unlikely to be an effective therapy and raises the question of whether toxicity arises from superoxide-mediated oxidative stress. Aggregates containing SOD1 were common to disease caused by different mutants, implying that coaggregation of an unidentified essential component or components or aberrant catalysis by misfolded mutants underlies a portion of mutant-mediated toxicity.     

The ability of non-invasive physiological tests to detect arterial occlusions in the lower extremity. An ROC study with particular regard to recruitment of patients for clinical trials

In the prerandomization phase of a clinical trial it is essential to be able to exclude, in a non-invasive way, patients who cannot be randomized into the trial. The ability of routine non-invasive physiological examinations to detect arterial occlusion in the lower extremities was investigated in 182 patients with hypercholesterolaemia. Ankle blood pressure measurement, pulse oscillometry, digital pulse plethysmography and treadmill and cycle exercise tests were performed as part of the prerandomization phase of the Probucol Quantitative Regression Swedish Trial (PQRST). The PQRST was designed to compare the antiatherosclerotic effect of two different lipid-lowering regimens. Before randomization the patients also underwent aorto-femoral arteriography, which was used as 'gold standard'. The results were analysed with ROC methodology. Ankle blood pressure measurement (ABP) and inclination time (IT), measured with digital pulse plethysmography, without significant mutual difference, were the variables, best able to detect occlusions. For ABP, the AZ-values were 0.85, 0.82 and 0.94 in detection of right-sided, left-sided and bilateral occlusion, respectively. The corresponding figures for IT were AZ = 0.86, 0.91 and 0.93. If a bilateral occlusion was predicted in a patient with an ABP value of < = or 0.98, a specificity of 0.90 and a sensitivity of 0.87 were obtained, using arteriography as reference method. For IT, with a critical value of 320 ms, sensitivity and specificity were 0.83 and 0.90, respectively.     

Capnography: assessing end-tidal CO2 levels

The purpose of this article is to describe the nurse's role in caring for patients with capnography. Capnography provides a continuous and non-invasive measure of arterial partial pressure of carbon dioxide (PaCO2) throughout the entire respiratory cycle. Used correctly, this technology assists the critical care nurse in providing adequate oxygenation and ventilation to the unstable patient.     

Apomorphine-induced yawning in the rat: influence of fasting and time of day

Yawning behavior is an experimental tool to study physiological responses, to elucidate the mechanisms of action of some drugs and hormones, and it is also a paradigm for some diseases and for dopamine (DA) agonists' clinical use. In this study, the effects of 24- and 48-h fasting as well as the influence of the light-dark cycle on apomorphine (APO)-induced yawning were evaluated. Initially, control and 48-h-fasted adult male rats were tested for yawning induced by APO (50, 100, 150 micrograms/kg, SC). The most effective dose tested was 100 micrograms/kg. Fasting significantly lowered yawning in all doses tested. Comparison between 24- and 48-h-fasted rats for APO (100 micrograms/kg)-induced yawning showed no significant difference between groups. Ad lib-fed groups were tested for APO (100 micrograms/kg)-induced yawning in both the light and in the dark phases of the cycle. Total number of yawnings increased significantly in the dark period. The present data show that fasting reduces and dark period increases APO-induced yawning in rats, suggesting that these conditions modulate the expression of this behavior.     

A cytoplasmic acyl-protein thioesterase that removes palmitate from G protein alpha subunits and p21(RAS)

Thioacylation is one of a handful of reversible covalent protein modifications, but the enzymes responsible for addition and removal of long chain fatty acids from protein cysteine residues in vivo have not yet been identified. The alpha subunits of some heterotrimeric G proteins cycle between thioacylated and deacylated states in a receptor-regulated fashion. We have identified, purified, and characterized an enzyme acyl-protein thioesterase that deacylates Galpha proteins and at least some other thioacyl protein substrates, including Ha-RAS. The action of this enzyme on thioacylated heterotrimeric Gs is regulated by activation of the G protein. Although native and recombinant acyl-protein thioesterases act as both acyl-protein thioesterases and lysophospholipases in vitro, we demonstrate by transfection that the enzyme can accelerate the turnover of thioacyl groups on Gsalpha in vivo.     

Replicable unconscious semantic priming

In 4 experiments, subjects classified visually presented target words as pleasant-unpleasant words or male-female first names. Prime words were similar (congruent) or dissimilar (incongruent) in meaning to targets. Brief duration of prime words (17, 33, or 50 ms), along with pre- and postmasking, prevented most subjects from perceiving their physical and semantic properties. By constraining response latencies to fall within a response window--a narrow time band that occurred earlier than subjects would ordinarily respond--these experiments consistently produced subliminal priming effects, indicated by greater error rates for incongruent than congruent priming trials. This conclusion was confirmed by analyzing magnitude of priming as a regression function of prime perceptibility using the method of A. G. Greenwald, M. R. Klinger, and E. S. Schuh (1995). The data of each experiment passed their significant-intercept criterion for demonstrating unconscious cognition.     

Cloning of a human UDP-galactose:2-acetamido-2-deoxy-D-glucose 3beta-galactosyltransferase catalyzing the formation of type 1 chains

Biochemical evidence suggests that the galactosyltransferase activity synthesizing type 1 carbohydrate chains is separate from the well characterized enzyme that is responsible for the synthesis of type 2 chains. This was recently confirmed by the cloning, from melanoma cells, of an enzyme capable of synthesizing type 1 chains, which was shown to have no homology to other galactosyltransferases. We report here the molecular cloning and functional expression of a second human beta3-galactosyltransferase distinct from the melanoma enzyme. The new beta3-galactosyltransferase has homology to the melanoma enzyme in the putative catalytic domain, but has longer cytoplasmic and stem regions and a carboxyl-terminal extension. Northern blots showed that the new gene is present primarily in brain and heart. When transfected into mammalian cells, this gene directs the synthesis of type 1 chains as determined by a monoclonal antibody specific for sialyl Lewisa. A soluble version of the cloned enzyme was expressed in insect cells and purified. The soluble enzyme readily catalyzes the transfer of galactose to GlcNAc to form Gal(beta1-3)GlcNAc. It also has a minor but distinct transfer activity toward Gal, LacNAc, and lactose, but is inactive toward GalNAc.     

Nasal allergen challenge and immunotherapy control

Nasal allergen challenges, despite not reproducing exactly natural allergen exposure, are a very useful method to understand the complex cellular kinetics and cellular interactions that occur in allergic rhinitis. Cell-specific soluble mediator measurements can give useful diagnosis information as well as complementary information regarding the monitoring of specific immunotherapy. In this article we present data concerning eosinophil cationic protein and tryptase measurements after nasal allergen and the influence of specific immunotherapy on nasal peak flow before and 1, 2 and 3 years after starting immunotherapy.     

The fibroblast-populated collagen microsphere assay of cell traction force--Part 2: Measurement of the cell traction parameter

In Part 1 of this work, we formulated and analyzed a mathematical model for our fibroblast-populated collagen microsphere (FPCM) assay of cell traction forces (Moon and Tranquillo, 1993). In this assay, the FPCM diameter decreases with time as the cells compact the gel by exerting traction on collagen fibrils. In Part 1 we demonstrated that the diameter reduction profiles for varied initial cell concentration and varied initial FPCM diameter are qualitatively consistent with the model predictions. We show here in Part 2 how predictions of a model similar to that of Part 1, along with the determination of the growth parameters of the cells and the viscoelastic parameters of the gel, allow us to estimate the magnitude of a cell traction parameter, the desired objective index of cell traction forces. The model is based on a monophasic continuum-mechanical theory of cell-extracellular matrix (ECM) mechanical interactions, with a species conservation equation for cells (1), a mass conservation equation for ECM (2), and a mechanical force balance for the cell/ECM composite (3). Using a constant-stress rheometer and a fluids spectrometer in creep and oscillatory shear modes, respectively, we establish and characterize the linear viscoelastic regime for the reconstituted type 1 collagen gel used in our FPCM traction assay and in other assays of cell-collagen mechanical interactions. Creep tests are performed on collagen gel specimens in a state resembling that in our FPCM traction assay (initially uncompacted, and therefore nearly isotropic and at a relatively low collagen concentration of 2.1 mg/ml), yielding measurements of the zero shear viscosity, mu 0 7.4 x 10(6) Poise), and the steady-state creep compliance, J0e. The shear modulus, G (155 dynes/cm2), is then determined from the inverse of J0e in the linear viscoelastic regime. Oscillatory shear tests are performed in strain sweep mode, indicating linear viscoelastic behavior up to shear strains of approximately 10 percent. We discuss the estimation of Poisson's ratio, v, which along with G and mu 0 specifies the assumed isotropic, linear viscoelastic stress tensor for the cell/collagen gel composite which appears in (3). The proliferation rate of fibroblasts in free floating collagen gel (appearing in (1)) is characterized by direct cell counting, yielding an estimate of the first-order growth rate constant, k (5.3 x 10(-6) s-1). These independently measured and estimated parameter values allow us to estimate that the cell traction parameter, tau 0, defined in the active stress tensor which also appears in (3), is in the range of 0.00007-0.0002 dyne.cm4/mg collagen.cell.(ABSTRACT TRUNCATED AT 400 WORDS)