Modification of human polymorphonuclear neutrophilic cell (PMN)-adhesion on biomaterial surfaces by protein preadsorption under static and flow conditions

Biomaterials induce a specific reaction after implantation in the human body. This reaction depends on the chemical and physico-chemical properties of the material as well as on the site and type of implantation. We have used a dynamic model, the parallel-plate flow-chamber, to examine the interactions of different biomaterials with polymorphonuclear neutrophilic cell (PMN) and how these interactions are influenced by protein preadsorption. Our results clearly show that for hydrophobic materials, glass and PE, which induce a prominent adhesion of PMN, the mixture of albumin and fibrinogen induces the best inhibitory effect. On hydrophilic biomaterial surfaces, untreated TCPS and PC-coated TCPS, reveal only a minor influence of adsorbed proteins on PMN adhesion because of a primary low adhesive surface for PMN and proteins as well. Human citrated plasma leads only to a slight inhibition of PMN adhesion. On the hydrophobic materials, glass and PE, bovine serum albumin (BSA) had the best anti-adhesive potential with respect to PMN. The coating using phosphorylcholine is an excellent surface modification to prevent PMN-adhesion and protein adsorption. The results of our experiments suggest that investigations under static and flow conditions are also needed to determine the influence of protein adsorption on other relevant blood cell populations, for example, platelets and monocytes.     

Cross-reactive metal ion sensor array in a micro titer plate format

A cross-reactive array in a micro titer plate (MTP) format is described that is based on a versatile and highly flexible scheme. It makes use of rather unspecific metal ions probes having almost identical fluorescence spectra, thus enabling (a) interrogation at identical analytical wavelengths, and (b) imaging of the probes contained in the wells of the MTP using a CCD camera and an array of blue-light-emitting diodes as a light source. The unselective response of the indicators in the presence of mixtures of five divalent cations generates a characteristic pattern that was analyzed by chemometric tools. The fluorescence intensity of the indicators was transferred into a time-dependent parameter applying a scheme called dual lifetime referencing. In this method, the fluorescence decay profile of the indicator is referenced against the phosphorescence of an inert reference dye added to the system. The intrinsically referenced measurements also were performed using blue LEDs as light sources and a CCD camera without intensifiers as the detector. The best performance was observed if each well was excited by a single LED. The assembly allows the detection of dye concentrations in the nanomoles-per-liter range without amplification and the acquisition of 96 wells simultaneously. The pictures obtained form the basis for evaluation by pattern recognition algorithms. Support vector machines are capable of predicting the presence of significant concentrations of metal ions with high accuracy.     

What do people want to know about psychotherapy?

Assessed information people want about psychotherapy, and the effect of prior exposure to a written consent form on preferences for information. 108 adults, half of whom had received a written informed consent form, answered an open-ended question about their preferences for information. Ss most frequently asked for information about the therapist, especially personal characteristics. Least frequently cited were items concerning appointments, alternatives, and confidentiality. Ss exposed to the written consent form were more likely to ask about confidentiality and financial arrangements and, if they had not had previous therapy experience, were less likely to ask about personal characteristics of the therapist. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schnelle fluorimetrische Bestimmung von Chlortetracyclin in Fleisch und Knochen

European Food Research and Technology - Antibiotica, einschließlich der Tetracycline, werden in biologischem Material üblicherweise mit mikrobiologischen Methoden bestimmt. Die...     

Phytoalexin induction in rubiaceae

Phytoalexin responses were measured by modified drop-diffusate and facilitated diffusion techniques after fungal inoculation of leaves of 32 Rubiaceae species from Brazilian forest and savanna. Such responses presented a trend similar to that previously observed for a broad sample of dicotyledonous plants and are more frequently positive for the more primitive (or slower growing) trees than for the advanced (or faster growing) herbs. Fifteen of these species analyzed during a one-year period showed that positive phytoalexin responses are stronger for the rainy (and hotter) than for the dry (and cooler) season. Species that contain relatively large quantities of phenolics gave invariably negative responses. Positive responses are not necessarily associated with the appearance of new substances within leaf tissue and are thus caused by inhibitins rather than by phytoalexins. These results are discussed recognizing that the tested plants are subject to the multifarious influences of their natural environment and of a possible conjugate-caused compartmentation of plant metabolites.Taken in part from the MSc thesis presented by M.R.B. to Universidade de São Paulo (1988).     

Analysis and performance evaluation of HYPERchannel access protocols

HYPERchannel [1,3,5,7] is a local network configuration with random access to the global transmission medium and with ‘Carrier Sense’ techniques. Conflicts are resolved by a fixed priority scheduling of retransmissions.This paper presents a performance evaluation of HYPERchannel access protocols for different types of user systems. Analytical results and asymptotic relations are obtained for the throughput of HYPERchannel under different load characteristics.The fixed priority rule for retransmissions discriminates against low priority users; a modification of the access scheme (‘Fair HYPERchannel’) is proposed which compensates for this undesirable effect. The performance of this new protocol version is also evaluated.In a final section, the access schemes of HYPERchannel are compared with similar access protocols.     

Selective recovery of copper from copper-nickel sulfide concentrates by applying segregation technology

Copper can be selectively segregated from roasted copper-nickel sulfide concentrates. Conditions are reported for desulfurizing-roasting followed by segregation treatment to selectively reduce and segregate copper without nickel contamination. A process is described which is applicable for treating low grade sulfide concentrates such as are produced in Botswana (4.6 pct Cu, 3.1 pct Ni) and higher grade concentrates that can potentially be produced from sulfide deposits in Minnesota (13 pct Cu, 2.5 pct Ni). Steps include roasting to remove at least 97 pct of the sulfur, segregation treatment of calcine and flotation to recover a copper product, a middlings fraction which is recycled to the desulfurizing roast and a tailings fraction which can be subsequently treated for nickel recovery. LAMAR D. COFFIN, formerly Senior Research Metallurgist at AMAX Base Metals R&D, Inc., has retired.