Axonal dysfunction and disability in a relapse of multiple sclerosis: longitudinal study of a patient

In a 6-year longitudinal study of a patient with relapsing progressive multiple sclerosis (MS), we used proton magnetic resonance spectroscopy to assess N-acetylaspartate (NAA) from a large central brain volume to evaluate the relationship between this marker of neuronal integrity and clinical disability. During the follow-up period, there was one major relapse and its subsequent partial remission. Changes in the brain NAA to creatine ratio correlated strongly with clinical disability (Spearman rank coefficient = -0.73, p < 0.001). We interpret this as evidence that axonal dysfunction or loss contributes to functional impairment of patients with MS. Because the NAA signal in the large volume of interest originated predominantly from white matter that appeared normal on conventional MRI, these results also suggest that some degree of axonal dysfunction may be widespread in acute, severe relapses.     

Fractionation of reactive perfluoropolyoxyalkylene oligomers

Fractional distillation, solubility fractionation, and column chromatographic separation have been applied in the study of fractionation of perfluoropoly(oxymethylene-co-oxy-ethylene) oligomers with ? CH₂OH end units, containing mono and bifunctional species. With a suitable choice of conditions, all three techniques proved to be useful for the preparation of fractions with narrow molecular weight distribution. Column chromatography allowed the separation of fractions having, in addition, sharp mono and bifunctionality. On the bsis of the experimental results, general indications for designing reactive oligomers fractionation procedures are discussed, prevalently centered on the copolymer end effect, which is typically present in this kind of compound. © 1995 John Wiley & Sons. Inc.     

Within-plot and within-plant variation for seed content of soya bean protease inhibitors

Experiments were designed to determine the seed content of protease inhibitors in different plants of a plot or at different nodes along the main stem. The inhibitory activity of the samples was measured in vitro using sodium benzoyl-DL-arginine-p-nitroanilide as chromogenic substrate and bovine trypsin as target enzyme. Six soya bean (Glycine max Merr) strains were used, three capable of synthesizing the Kunitz trypsin inhibitor (L62-364, Williams 82, and 594-1) and three lacking this particular function (L81-4590, L81-4871, and L83-4387). In all genotypes on trial, remarkable plant-to-plant variation was found, so that most strains had at least one part of the data distribution in common. Significant differences were also noted for antitryptic activities of seed samples collected at different positions on the main stem. Gradients interior to the plant varied according to the tested strain but those of Williams 82 and of its near isogenic line L81-4590 were very similar, indicating that the amount and type of variation depended on genotype and that changes in the inhibitory activity were attributable to variation in the synthesis of inhibitors other than Kunitz.     

Comparative In Vitro evaluation of cumulative release of the urinary antiseptics Nalidixic acid, Pipemidic acid, Cinoxacin, and norfloxacin from white beeswax Microspheres

The in vitro diffusion of nalidixic acid (1), pipemidic acid (2), cinoxacin (3), and norfloxacin (4) was studied. The transfer rate constants (k_d) from simulated gastro-intestinal juices to simulated plasma, throughout artificial wall lipid membranes, were defined. The k_d values suggested that the four drugs are absorbed both in gastric and intestinal environments in similar amounts. To obtain lack of gastric unwanted effects white beeswax microspheres containing 1, 2, 3, and 4 were investigated as a vehicle for the drug intestinal release; they were prepared by the meltable dispersion process using wetting agents. Discrete, reproducible free flowing microspheres were obtained. The drug content increased when the particle size growed; it ranged from 4% to 18%. More than 95% of the isolated microspheres were of particle size range 100-500 μm. The drug release was evaluated in vitro. Dissolution of entrapped active ingredients was greatly retarded allowing absorption only in the intestinal tract as result of microsphere formation.     

Optical sensing of flammable substances using porous silicon microcavities

A porous silicon multilayer, constituted by a Fabry–Pèrot cavity between two distributed Bragg reflectors, is exposed to vapor of several organic species. Different resonant peak shifts in the reflectivity spectra, ascribed to capillary condensation of the vapor in the silicon pores, have been observed. Starting from experimental data, the layer liquid volume fractions condensed in the sensing stack have been numerically estimated. Values ranging between 0.27 (for ethanol) and 0.33 (for iso-propanol) have been found. Time-resolved measurements show that the solvent identification occurs in less then 10 s.     

Evaluating the field bus data link layer by a Petri net-basedsimulation

The performance of the data link layer of the field bus, an emerging LAN architecture for control systems presently under standardization, is discussed and evaluated. Some aspects of the communication mechanism are presented, referring to the use of the two kinds of tokens of the protocol and pointing out their main features and the advantages and disadvantages offered by each one. The protocol was specified by extended timed Petri-nets and was evaluated by a suitable simulation tool. The results provide some criteria according to which the designer can choose, among the various mechanisms made available by the standard proposal, those which provide the most efficient solution for the scenario being considered     

Chebyshev approximation of recursive digital filters having specified amplitude and phase characteristics

The design of an IIR filter of prescribed amplitude and phase characteristics can be reduced to an approximation problem for complex valued functions. An algorithm for the solution of this problem is given and some numerical results are presented.     

Nitrogen application in dry-seeded delayed-flooded rice in Italy

Dry-seeded delayed-flooded rice in Italy is important in some areas with high sand content. The effects of N application timing and rates on grain yield, milling yield, plant height, total biomass, harvest index (HI) and crop N content were evaluated for dry-seeded delayed-flooded rice in Italy to increase the N use efficiency and to study N fertilizer recommendations. Two widely grown non-semi-dwarf varieties were studied: Drago and Loto. Three N rates were used: 60, 120 and 180 kg N ha^–1. For each rate the fertilizer was applied in seven splits across three growth stages: pre-sowing, pre-flooding and panicle differentiation. Drago produced higher yields and N application at all stages increased yield. Late N application caused the development of secondary sterile tillers, decreasing harvest index. Loto responded to earlier N applications but not to late N applications. In contrast with other trials outside Italy, pre-plant N fertilization was effective in increasing yield. Brown rice and total milled rice yields were higher for Loto. Increasing the applied N rate increased the head rice yield range. With low N no low values were recorded and variation between splits was small. With high N the highest head yield was observed with split application. Height was significantly affected by N rate and split, with a range of 65 to 92 cm and 54 to 86 cm for Drago and Loto, respectively. N application at tillering was more effective. N rate and split affected biomass and decreased HI. Crop N content at maturity was affected by late N application and by total applied fertilizer. N content in the panicle showed lower variation with N split and rate and was negatively correlated with yield. At 120 and 180 kg N ha^–1 all nitrogen applied pre-flooding gave good results in both sites, but the best results were obtained with N split at pre-sowing and pre-flooding, with low yield increase moving from 120 to 180 kg N ha^–1. We recommend late N applications for Drago (medium-late variety), but not for Loto (early variety).