Immobilization of paraoxonase onto chitosan and its characterization.

Paraoxonase was covalently immobilized onto a glutaraldehyde containing amino group functionalized chitosan surface by chemical immobilization at pH 8.0. The amount of covalently bound hPON1 was found to be 32 mg/10 chitosan beads. The properties of immobilized enzyme were investigated and compared to those of free enzyme. The effects of various parameters such as pH, temperature, heat, and storage stability on immobilized enzyme were investigated. Kinetic parameters of the immobilized enzyme were also evaluated. Thermal and storage stability experiments were carried out. It was observed that the immobilized enzyme had longer storage stability and retained 50 % of its initial activity during 26 days.

A high-affinity recombinant antibody permits rapid and sensitive direct detection of myeloperoxidase.

Over the past 10 years, a growing field of research supporting the value of myeloperoxidase (MPO) as a prognostic indicator in acute cardiac pathophysiologies has emerged. The availability of a rapid and disposable MPO detection platform would enable research clinicians to more readily assess MPO indications for guiding therapy and also facilitate clinicians at the patient interface to readily adopt MPO testing and potentially drive more informed prognoses. Here we describe the isolation of a high-affinity avian MPO-specific recombinant antibody panel using phage display. Rapid isolation of a suitable single-chain variable fragment (scFv) antibody was facilitated using a surface plasmon resonance (SPR)-based "off-rate ranking" screening process. The selected scFv was then successfully incorporated into a rapid, simple, and sensitive one-step lateral flow immunoassay (LFIA) for the detection of MPO. This "one-step" feature of the developed assay was made possible by the scFv's strong affinity for MPO, obviating the need for sandwich signal enhancement steps. The assay's rapid performance was also further enhanced by exploiting the intrinsic enzymatic properties of MPO in its final detection. Use of the optimized LFIA facilitated the sensitive detection of MPO in MPO-depleted serum within clinically relevant reference ranges.

Effect of a plant histaminase on asthmalike reaction induced by inhaled antigen in sensitized guinea pig.

This study evaluates the effects of a copper amine oxidase (histaminase) purified from the pea seedling as a free or immobilized enzyme on asthmalike reactions to inhaled antigen in actively sensitized guinea pig in vivo. Male albino guinea pigs, sensitized with ovalbumin, were challenged with the antigen given by aerosol; free histaminase or CNBr-Sepharose immobilized histaminase was given intraperitoneally (20 microg, 3 or 24 h before antigen challenge) or by aerosol (4 microg, 30 min before or during ovalbumin aerosol). The following parameters were examined: latency time for the onset of respiratory abnormalities, cough severity score, and occurrence and duration of dyspnea. We also evaluated lung histopathology, mast cell degranulation, and lung myeloperoxidase and malonydialdehyde levels. Histaminase significantly reduced the severity of cough and the occurrence of dyspnea and delayed the onset of respiratory abnormalities. Both enzymes prevented bronchial constriction, pulmonary air space inflation, leukocyte infiltration (evaluated as myeloperoxidase activity), and lipoperoxidation of cell membranes (evaluated as malonyldialdehyde production). No relevant differences in pharmacological potency were noted between free or immobilized enzyme. This study provides evidence that histaminase counteracts acute allergic asthmalike reaction in actively sensitized guinea pigs, raising the possibility of new therapeutic strategies for allergic asthma in humans.

A Phase I-II trial of polyethylene glycol-conjugated L-asparaginase in patients with multiple myeloma.

BACKGROUND: Multiple myeloma remains an incurable disease. New agents are needed to improve therapy for patients with this disease. Previous investigators evaluated in vitro sensitivity of myeloma cells to polyethylene glycol-conjugated L-asparaginase (PEG-L-asparaginase) using the human tumor clonogenic assay. Of the 19 myeloma samples evaluated, 63% were inhibited at 0.075 IU/mL, and 74% were inhibited at 0.75 IU/mL. PEG-L-asparaginase is a form of Escherichia coli-derived L-asparaginase that is bound covalently to polyethylene glycol. Compared with the native form, it has a longer half-life and is less likely to cause allergic reactions. METHODS: The authors conducted a Phase I-II trial using PEG-L-asparaginase as a single agent in patients with recurrent and/or refractory multiple myeloma. RESULTS: Twenty-two patients received a median of two doses of PEG-L-asparaginase. In the 17 patients who are evaluable for response, a complete response was observed in one patient after four doses, and stable disease was observed in eight patients. Progression of disease was the reason for termination from study in the remaining eight patients. The median survival was 31.7 months, with four patients who were alive at 72 months after the start of therapy. Grade 3-4 toxicity was noted by the PEG-L-asparaginase 2000 mg/m(2) level. Severe allergic reactions were noted only at the highest dose level. CONCLUSIONS: Current data suggest that the maximal tolerated dose for single agent PEG-L-asparaginase in relapse/refractory multiple myeloma patients is 1000 mg/m(2) every 4 weeks. We could not identify any correlation between dose, plasma level and response. In this advanced group of patients we noted stable disease and/or response in 52% of evaluable patients. PEG-L-asparaginase has lower tolerance when used in the standard dosage as a single agent in this group of patients. We therefore recommend further studying of PEG-L-asparaginase dose of 1000 mg/m(2) on alternate weeks with steroids and/or other immune modulators.

Encapsulation of PEG-urease/PEG-AlaDH enzyme system in erythrocyte.

No intravenously injectable enzyme preparate containing urease as an alternetive to hemodialysis, hemoperfusion and CAPD systems in patients having chronic renal failure has been encountered in literature. In this study, it has been aimed to convert blood urea to alanine by using PEG-urease/PEG-AlaDH enzyme pair encapsulated within living erythrocyte. In this system, urea is decomposed into NH3 and HCO3- and the ammonia released is converted into alanine by reacting pyruvate under the catalytic action of alaninedehydrogenase. The production of pyruvate and NADH by erythrocyte required in the second stage of the reaction will make the process a feasible and ceaseless one. The success of the system will enable the renal patients with diabetes mellitus. Urease and AlaDH were covalently immobilized on activated PEG. PEG-urease/PEG-AlaDH were encapsulated in erythrocyte (1/1)(v/v) by using slow dialysis methods. The activity of enzyme system, encapsulation yield and hemogram analysis were determined for each sample.

Continuous-flow/stopped-flow system incorporating two rotating bioreactors in tandem: application to the determination of alkaline phosphatase activity in serum.

Two rotating bioreactors in tandem have been incorporated into a continuous-flow/stopped-flow sample/reagent processing setup for the determination of alkaline phosphatase (EC3.1.3.1) activity in serum samples. The strategy circumvents incompatibility of buffer systems as well as that of the immobilized enzymes utilized in the bioreactors (alkaline phosphatase and alcohol oxidase, EC 1.1.3.13). The determination is indirect in nature although recorded responses are directly related to the enzyme activity in the sample. It couples the following enzyme-catalyzed reactions: (1) hydrolysis of p-nitrophenyl dihydrogen phosphate catalyzed by alkaline phosphatase, (2) enzymatic reaction between unreacted p-nitrophenyl dihydrogen phosphate with methanol, and (3) conversion of the residual methanol to the corresponding aldehyde and H2O2, catalyzed by alcohol oxidase. The H2O2 is amperometrically determined at a stationary Pt-ring electrode (applied potential + 0.600 V vs a Ag/AgCl, 3.0 M NaCl reference).

Carrier membrane as a stationary phase for affinity chromatography and kinetic studies of membrane-bound enzymes.

The use of membrane supports as stationary phase, coupled with ligands of choice, allows all kinds of chromatography [Dj. Josic, K. Zeilinger, Y. Lim, M. Raps, W. Hofmann and W. Reutter, J. Chromatogr., 484 (1989) 327] and offers a powerful alternative to both soft gel chromatography and high-performance liquid chromatography. In this work we present affinity membrane chromatography for purification of the enzyme carbonic anhydrase from haemolysates of human erythrocytes. Furthermore, the coupling of the enzymes to the membrane support allows kinetic investigations. As an example, kinetic experiments were carried out by means of carbonic anhydrase coupled to the membrane support using 4-nitrophenyl acetate and 2-chloro-4-nitrophenyl acetate as substrates.

[Modified and immobilized preparations of basic polyvalent protease inhibitor for potential medical use]. / Modifitsirovannye i immobilizovannye preparaty osnovnogo polivalentnogo ingibitora proteaz dlia potentsial'nogo meditsinskogo ispol'zovaniia.

Several procedures for immobilization of basic polyvalent inhibitor of proteases on soluble and insoluble matrices of various chemical nature were studied. Water-soluble high molecular derivatives of the proteases inhibitor were produced, which exhibited the unaltered constants of trypsin inhibition, slower rate of elimination from circulation and the hepatotropism as compared with the native inhibitor. The higher therapeutic efficiency of the high molecular derivative of the proteases inhibitor and of the affinity sorbent, produced on its basis, as compared with the conventional methods of the experimental acute pancreatitis treatment, were confirmed by a number of biochemical data.

Types of ocular attacks and lysosomal enzymes in Behçet's disease.

The activities of the lysosomal enzymes of leukocytes were correlated with the types of ocular attacks of Behcet's disease, ie, the anterior or posterior types. No significant correlation was found between the types of attacks and the activities of acid phosphatase and beta-glucuronidase. Myeloperoxidase (MPO) activity in the neutrophils, however, was significantly lower in the posterior type than in the anterior type. In selected cases, the time-course of the MPO activity was studied: the activity decreased at attacks and showed a recovery as the symptoms subsided. The recovery after the attacks was faster in the anterior type than in the posterior type. The difference between the MPO activities in the two types of attacks was thought to be due to the fact that the posterior type attack shows more severe ocular inflammation than the anterior type attack. It is possible that the MPO is released from the neutrophils just before the onset of the ocular attacks.

Phenylalanine ammonia-lyase entrapped in fibers.

Phenylalanine ammonia-lyase extracted form Rhodotorula rubra (IFO 1101) was immobilized into cellulose triacetate fibers made hemocompatible by physical blend with a platelet anti-aggregating agent. The entrapped enzyme could operate at physiological values of phenylalanine and tyrosine reducing their level to traces within a few hours. The optimum pH value for the entrapped enzyme shifted from 8.0 to 9.0. At blood pH the activity was about 68 per cent of the maximum. The entrapped enzyme retained its original activity in blood for more than 50 days.