Macroporous copolymer matrix: 1. Effectiveness of different diisocyanate spacer arms to bind cyclodextrins.

Cross-linked macroporous beaded polymer matrices, with pendant hydroxyl groups, were synthesized by the copolymerization of 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate using suspension polymerization methodology. Novel affinity chromatography matrices were synthesized using various diisocyanates as bifunctional reagents to couple the macroporous polymeric supports, of controlled particle size distribution, with alpha and beta-cyclodextrins. The optimal conditions to couple the hydroxyl groups of cyclodextrin (ligand) and the polymeric supports through urethane linkages were established iteratively using various diisocyanates. Efficacy of ligand binding on the matrix and nonspecific interactions of the synthesized affinity matrices were evaluated to establish the best support and spacer arm. 2,4-Tolylene diisocyanate was established as the best spacer arm on the basis of high ligand binding and low nonspecific interactions. The characteristics of the synthesized affinity matrices toward the adsorption of alpha and beta-cyclodextrin glycosyltransferase (CGTase) were investigated. The binding of beta-CGTase was the highest on affinity matrices with the polymeric methylene diisocyanate spacer. The optimal conditions to regenerate the matrices were also established.

Development of tailor-made glycidyl methacrylate-divinyl benzene copolymer for immobilization of D-amino acid oxidase from Aspergillus species strain 020 and its application in the bioconversion of cephalosporin C.

A tailor-made glycidyl methacrylate-divinyl benzene (GMA-DVB) copolymer PC-3 was evolved by studying the effect of synthesis variables on binding and expression of D-amino acid oxidase (DAAO) from Aspergillus species strain 020. Almost quantitative binding (100%) and a high yield of immobilization per unit of enzyme loaded was achieved. Optimum pH, optimum temperature and K(m)95% was achieved by using 3% (w/v) solution of ceph C, 48 U of DAAO per g of ceph C, keeping dissolved oxygen level above 50%, maintaining the pH between 7.6 and 7.8 and temperature at 24 degrees C. The immobilized DAAO was used for 60 cycles in a stirred tank reactor.

Early deaths with thrombolytic therapy for acute myocardial infarction in corticosteroid-dependent rheumatoid arthritis.

Intravenous thrombolytic therapy has become standard treatment for acute myocardial infarction (AMI). We describe three patients with long-standing seropositive rheumatoid arthritis (RA) on chronic corticosteroid therapy who experienced very early (1-6 h) mortality after the use of intravenous thrombolytic therapy for the treatment of AMI. All three patients likely experienced electromechanical dissociation (EMD). Their charts were evaluated in depth, and the literature was reviewed in regard to possible etiopathologic mechanisms. Within 1-6 h of apparently successful thrombolytic therapy for AMI, these three patients experienced sudden and profound bradycardia and hypotension and could not be resuscitated. The potential occurrence of EMD in all three patients raises the possibility of accelerated myocardial rupture, as EMD is one of the clinical hallmarks of this condition. As suggested by the three clustered cases, this heretofore undescribed association between sudden unexpected cardiac death and thrombolytic therapy for AMI in patients with seropositive, corticosteroid-dependent RA suggests that further study and observation are needed. This deleterious association, if verified, has important implications for the treatment of AMI in patients who have RA and are corticosteroid dependent.

Beaded reactive polymers. 3. Effect of triacrylates as crosslinkers on the physical properties of glycidyl methacrylate copolymers and immobilization of penicillin G acylase.

Various glycidyl methacrylate (GMA) copolymers were synthesized by suspension polymerization, using pentaerythritol triacrylate (PETA), trimethylolpropane triacrylate (TMPTA), and trimethylolpropane trimethacrylate (TRIM) as crosslinking comonomers. These copolymers were evaluated for the immobilization of penicillin G acylase. Broad pore-size distribution that was observed was in the range 5-300 nm. Both surface area and pore volume increased with increase in the mole fraction of crosslinking comonomer (increasing crosslink density). The pore volume of the copolymers was more than doubled by including lauryl alcohol as porogen. Binding of penicillin G acylase (PGA) was quantitative on highly crosslinked copolymers. The expression of bound PGA was better on the relatively more hydrophilic GMA-TMPTA and GMA-PETA copolymer supports compared to the GMA-TRIM copolymers. Among the different copolymers studied, GMA-TMPTA copolymer 7411 exhibited highest activity of immobilized penicillin G acylase (167.4 IU/g) with 35.1% expression.

Image characteristics in applications utilizing dilute subaperture arrays.

When a large aperture is synthesized with an array of smaller subapertures for high-resolution imaging applications, it is important not only to arrange the subapertures to achieve minimal spatial frequency redundancy but also to choose the size of the subapertures (i.e., the dilution ratio) necessary to achieve the best possible image quality. Spurious or ghost images often occur even for nonredundant dilute subaperture arrays. We show that array configurations producing a uniform modulation transfer function will not exhibit these undesirable ghost images. A prescription that is unique and original (to the best of our knowledge) is then presented for constructing both one-dimensional and two-dimensional configurations of dilute subaperture arrays that results in a uniform spatial frequency response with an arbitrarily high spatial resolution for reciprocal path-imaging applications.

Effects of surface scatter on the optical performance of x-ray synchrotron beam-line mirrors.

The increased availability of advanced synchrotron radiation sources is resulting in a resurgence of activity in the field of x-ray and extreme ultraviolet imaging systems. However, scattering effects caused by residual optical fabrication errors frequently dominate geometrical design errors in the degradation of image quality at these very short wavelengths. Traditional optical design and analysis techniques (geometrical ray tracing) are therefore inadequate for predicting the performance of high-resolution synchrotron beam-line optics. A surface-scattering theory must be implemented to model the image degradation effects of residual surface irregularities over the entire range of relevant spatial frequencies. This includes small-angle scattering effects caused by mid-spatial-frequency surface errors that fall between the traditional figure and finish specifications. Performance predictions are presented parametrically to provide insight into the optical fabrication tolerances necessary to meet the requireme nts of a specific application.

Adsorption and expression of penicillin G acylase immobilized onto methacrylate polymers generated with varying pore generating solvent volume.

Adsorption and expression of penicillin G acylase was studied on macroporous methacrylate polymer beads of differing pore volume, generated with kerosene. The absorption and expression of the penicillin G acylase was dependent on pore volume. Maximum expression of 57% of adsorbed enzyme was obtained on beads synthesized with 40 mL of kerosene, indicating minimum pore-diffusion limitations.