Two-dimensional profiles of fumonisin B1 production by Fusarium moniliforme and Fusarium proliferatum in relation to environmental factors and potential for modelling toxin formation in maize grain

This study has examined in detail the effect of temperature (7-37 degrees C) and water availability (water activity, a(w), 0.89-0.97) on fumonisin B1 (FB1) production by an isolate of Fusarium moniliforme and F. proliferatum on irradiated maize grain after incubation for 28 days. The optimum conditions for F. moniliforme and F. proliferatum were 30 degrees C at 0.97 a(w) and 15 degrees C at 0.97 a(w), respectively. The maximum concentrations were 2861 mg kg(-1) and 17,628 mg kg(-1) dry wt. maize grain, respectively. At marginal a(w)/temperature conditions for growth (e.g. 0.89-0.91 a(w)) no FB1 was detected (<0.1 mg kg(-1)). A high variability was found between replicates for F. moniliforme, but not for F. proliferatum. These data were used to construct two-dimensional diagrams of all the a(w) x temperature conditions favourable for FB1 production for the first time. The data were also subjected to a polynomical regression, which demonstrated that there was a very good fit for the 15-30 degrees C range of temperature and at 0.97 a(w). However, at marginal environmental conditions this was not possible. This suggests that it may be possible to predict within a limited environmental range the potential for significant FB1 production.     

Effect of beta-glucan from oats and yeast on serum lipids

Heart disease is the leading cause of death in the U.S. One way to reduce the risk of developing the disease is to lower serum cholesterol levels by making dietary changes. In addition to reducing intake of total fat, saturated fat, and dietary cholesterol, serum cholesterol can be further reduced by added fiber, especially from sources rich in beta-glucan. In this review, two sources of beta-glucan are described; one source is oats and the other yeast. Their chemical structures and physical properties are compared, and their effect on serum lipid levels is described. Oat beta-glucans are found in various breakfast cereals and snacks. Usually, several servings of these products are required to meet the Food and Drug Administration's claim of reducing the risk of heart disease. The yeast-derived fiber is a more concentrated source of beta-glucan than the oat product. It is currently being tested in a wide variety of food products.     

Elastic-plastic characterization of thin films with spherical indentation

Indentation characterization of thin films has most recently been investigated with currently available ultramicroindentation hardness instruments that use a pyramidal diamond tipped indenter. With these instruments determination of the hardness at depths of penetration as shallow as 5–10 nm is possible. However, the problems associated with such indenters are the inability to characterize the indenter tip radius and the fact that pointed indenters essentially perform tests at constant plastic strain. An alternative approach to measuring the mechanical properties of thin films is to use spherically tipped indenters of known tip radius and to follow the transition from elastic to plastic deformation. The Hertzian analysis provides the basis for determining the elastic behaviour and it may be modified to examine the elastic-plastic transition. From such observations it is possible to determine the variation in the mean indentation pressure with depth of penetration and to construct an equivalent stress-strain response of a material. Examples of this approach are given for bulk materials and metallic and polymeric thin films. Data have been collected with a UMIS-2000 instrument and have been analysed and simulated on the basis of the approach outlined above.     

Tools to engineer new technologies into applications

How will consumers, engineers, and businesses benefit from the latest computer technology? Technologists envision graphical, multimedia interfaces to the information highway, but technology like graphical user interfaces, multimedia, and groupware does not appear in applications by magic. Whether the target application is an information system, a consumer product, or a real-time embedded system, developers must expand their engineering environments to incorporate tools for new technologies. To win the race to market, suppliers must pursue various approaches to improve their engineering process. The authors explore these key aspects of development support for new applications: technology-specific tools, reuse, computer-aided software engineering, testing, and integrated development environments     

Effects of ischaemia-reperfusion and cyclosporin-A on cardiac muscle ultrastructure

The present study investigates the effects on the cardiac muscle cell of two of the determining factors for the success of organ transplant; ischaemia-perfusion and immunosuppressive treatment with cyclosporin-A (CsA). To this end an abdominal, heterotopic heart transplant model in singenic Sprague-Dawley rats was employed. Three study groups were established: Group I (control, n = 15) animals undergoing heart transplant without treatment; Group II (n = 15) animals undergoing heart transplant and subjected to a daily dose of CsA in a cremophor vehicle (Sandimun) (5 mg/kg/sc); Group III (n = 15): animals undergoing heart transplant and administered a daily dose of pure CsA (5 mg/kg/sc). Recipient animals were sacrificed 7, 14, 21, 30 and 50 days after transplant. During the post-operative period, heart function was assessed by daily abdominal palpation. Graft specimens obtained at each follow-up period were subjected to light and transmission electron microscopy. Immunohistochemical analysis of specimens was performed using the rat macrophage-specific monoclonal antibody MCA-341. The ischaemia/reperfusion process induced considerable alteration to cardiac muscle cells of control animals. Effects, apparent after the first week of transplant, included mitochondrial swelling and loss of cristae, hypertrophy of the sarcoplasmic reticulum and structural changes to sarcomeres. Two weeks after transplant, the myocardium was infiltrated by inflammatory cells. These effects diminished 30 days post-transplant. Cardiac tissues of treated animals (groups II and III) showed similar behaviour although, in the latter group, mitochondrial damage was greater and intense myocardial fibrosis took place. Infiltration of cardiac muscle by white blood cells did not take place until 3 weeks post-implant. These results indicate: a) The ultrastructural changes detected in cardiac fibres of animals of the three study groups were attributable to the ischaemia/reperfusion process rather than to treatment with CsA; b) CsA appears to augment mitochondrial damage and myocardial fibrosis; c) the inflammatory response was delayed and reduced by the immunosupressant; and d) the cremophor administration vehicle did not seem to exert an independent toxic effect on the myocardium.     

Development of orally active oxytocin antagonists: studies on 1-(1-[4-[1-(2-methyl-1-oxidopyridin-3-ylmethyl)piperidin-4-yloxy]-2- methoxybenzoyl]piperidin-4-yl)-1,4-dihydrobenz[d][1,3]oxazin-2-one (L-372,662) and related pyridines

The previously reported oxytocin antagonist L-371,257 (2) has been modified at its acetylpiperidine terminus to incorporate various pyridine N-oxide groups. This modification has led to the identification of compounds with improved pharmacokinetics and excellent oral bioavailability. The pyridine N-oxide series is exemplified by L-372,662 (30), which possessed good potency in vitro (Ki = 4.1 nM, cloned human oxytocin receptor) and in vivo (intravenous AD50 = 0.71 mg/kg in the rat), excellent oral bioavailability (90% in the rat, 96% in the dog), good aqueous solubility (>8.5 mg/mL at pH 5.2) which should facilitate formulation for iv administration, and excellent selectivity against the human arginine vasopressin receptors. Incorporation of a 5-fluoro substituent on the central benzoyl ring of this class of oxytocin antagonists enhanced in vitro and in vivo potency but was detrimental to the pharmacokinetic profiles of these compounds. Although lipophilic substitution around the pyridine ring of compound 30 gave higher affinity in vitro, such substituents were a metabolic liability and caused shortfalls in vivo. Two approaches to prevent this metabolism, addition of a cyclic constraint and incorporation of trifluoromethyl groups, were examined. The former approach was ineffective because of metabolic hydroxylation on the constrained ring system, whereas the latter showed improvement in plasma pharmacokinetics in some cases.     

Surface characterization using frequency diverse scatteringmeasurements and regularity models

Accurate classification and characterization of image regions is often an important goal for the users of coherent imaging systems such as synthetic aperture radar (SAR). Many surfaces measured by remote sensing systems can be stochastically described by a regularity model. This parametric point-process model describes a 1-D surface in terms of the mean and variance of the interscatterer distances. Variations of these parameters can describe scatterer distributions ranging from totally random to nearly periodic. Under certain conditions, a closed-form approximation to the mean power spectrum of finite-length data intervals exists. The estimation of model parameters from measured spectra can then be cast as an optimization problem in which the total squared error between the approximation and the simple periodogram is minimized. We examine the general performance limitations of such an optimization procedure, determining how approximation error, signal-to-noise ratio, and frequency-sampling rate affect the feasibility and accuracy of parameter estimation. We determine under what conditions the approximation may be used. We find that parameter estimation is feasible at a frequency-sampling rate that is well below that suggested by the power spectral density (PSD). This suggests that it is possible to obtain parameter estimates by comparing sparse narrow-band frequency measurements to the PSD of the point-process and thereby obtain information about the surface on subresolution scales     

Post-thaw sperm motility, cAMP concentration and membrane lipid peroxidation after stimulation with pentoxifylline and platelet-activating factor

Earlier studies have demonstrated that pentoxifylline (PTX) and platelet-activating factor (PAF) can significantly improve the motion parameters of post-thaw human spermatozoa. This study has investigated the effects of PAF, PTX and their combination on cyclic adenosine monophosphate (cAMP) concentrations and membrane lipid peroxidation (LPO) in post-thaw human spermatozoa. Washed spermatozoa from normal volunteers (n = 10) were cryopreserved in Test-yolk buffer using a standard protocol. After 2 weeks the sperm samples were thawed, washed and incubated with either 1 microM PAF, 3 mM PTX or 0.5 microM PAF plus 1.5 mM PTX. Video sequences were recorded at 0, 30, 60, and 120 min for analysis of sperm motion parameters using the Cell Track Sperm Analysis System. Concentrations of cAMP were assessed by radioimmunoassay, and LPO levels were measured by malondialdehyde-thiobarbituric acid reactivity. Our studies indicate a time-course stimulatory effect with overall maximal stimulation observed in samples treated with the combination of PAF and PTX. The maximal stimulation of percentage motility compared to control was observed at 60 min in samples treated with PAF, PTX, or PAF plus PTX. PAF plus PTX stimulated straight-line velocity (VSL), curvilinear velocity (VCL) and lateral head displacement (ALH) after 30 min incubation. The primary effect of PAF was observed on VSL, while the main effect of PTX was on VCL. cAMP concentrations were 3-fold higher than controls in samples treated with PTX or PAF plus PTX. cAMP concentrations in PAF-treated samples did not differ significantly from controls. No significant differences were observed between any groups for LPO.(ABSTRACT TRUNCATED AT 250 WORDS)