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The production of extracellular and mycelia-associated penicillin G acylase (maPGA) with Mucor griseocyanus H/55.1.1 by surface-adhesion fermentation using Opuntia imbricata, a cactus, as a natural immobilization support was studied. Enzyme activity to form 6-aminopencillanic acid (6-APA) from penicillin G was assayed spectrophotometrically. The penicillin G hydrolysis to 6-APA was evaluated at six different times using PGA samples recovered from the skim milk medium at five different incubation times. Additionally, the effect of varying the penicillin G substrate concentration level on the PGA enzyme activity was also studied. The maximum reaction rate, V (max), and the Michaelis constant, K (M), were determined using the Michaelis-Menten model. The maximum levels for maPGA and extracellular activity were found to be 2,126.50 international unit per liter (IU/l; equal to 997.83 IU/g of support) at 48 h and 755.33 IU/l at 60 h, respectively. Kinetics of biomass production for total biomass showed a maximum growth at 60 h of 3.36 and 2.55 g/l (equal to 0.012 g of biomass per gram of support) for the immobilized M. griseocyanus biomass. The maPGA was employed for the hydrolysis of penicillin G to obtain 6-APA in a batch reactor. The highest quantity of 6-APA obtained was 226.16 mg/l after 40-min reaction. The effect of substrate concentration on maPGA activity was evaluated at different concentrations of penicillin G (0-10 mM). K(M) and V(max) were determined to be 3.0 x 10(-3) M and 4.4 x 10(-3) mM/min, respectively.

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The complexity of biological processes often makes impractical the development of detailed, structured phenomenological models of the cultivation of microorganisms in bioreactors. In this context, data pre-treatment techniques are useful for bioprocess control and fault detection. Among them, principal component analysis (PCA) plays an important role. This work presents a case study of the application of this technique during real experiments, where the enzyme penicillin G acylase (PGA) was produced by Bacillus megaterium ATCC 14945. PGA hydrolyzes penicillin G to yield 6-aminopenicilanic acid (6-APA) and phenyl acetic acid. 6-APA is used to produce semi-synthetic beta-lactam antibiotics. A static PCA algorithm was implemented for on-line detection of deviations from the desired process behavior. The experiments were carried out in a 2-L bioreactor. Hotteling's T(2) was the discrimination criterion employed in this multivariable problem and the method showed a high sensibility for fault detection in all real cases that were studied.

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Piperacillin-tazobactam is a broad spectrum antimicrobial agent that can cause false-positive results in the commercial Platelia Aspergillus EIA test. So far, no study has been performed in Latin America to evaluate the clinical implication of this finding. Here we studied the potential for galactomannan detection in piperacillin-tazobactam batches commercialized in the Brazilian market. Five batches from distinct laboratories were tested in duplicate in the Platelia Aspergillus EIA according to the manufacturer's instructions. Only one drug showed crossreaction at a cut-off of 0.5. Human serum was spiked with this particular drug aiming to mimic achievable piperacillin-tazobactam concentrations in the serum. Results were all negative for galactomannan detection, even at high drug concentrations. Results from this pilot study suggest that piperacillin-tazobactam might not be a clinically significant cause of false-positive results in the Platelia Aspergillus EIA test in Brazil.

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Piperacillin-tazobactam is a broad spectrum antimicrobial agent that can cause false-positive results in the commercial Platelia Aspergillus EIA test. So far, no study has been performed in Latin America to evaluate the clinical implication of this finding. Here we studied the potential for galactomannan detection in piperacillin-tazobactam batches commercialized in the Brazilian market. Five batches from distinct laboratories were tested in duplicate in the Platelia Aspergillus EIA according to the manufacturer's instructions. Only one drug showed crossreaction at a cut-off of 0.5. Human serum was spiked with this particular drug aiming to mimic achievable piperacillin-tazobactam concentrations in the serum. Results were all negative for galactomannan detection, even at high drug concentrations. Results from this pilot study suggest that piperacillin-tazobactam might not be a clinically significant cause of false-positive results in the Platelia Aspergillus EIA test in Brazil.

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A recurrent doubt that occurs to the enzyme-kinetics modeler is, When should I stop adding parameters to my mechanistic model in order to fit a non-conventional behavior? This problem becomes more and more involving when the complexity of the reaction network increases. This work intends to show how the use of artificial neural networks may circumvent the need of including an overwhelming number of parameters in the rate equations obtained through the classical, mechanistic approach. We focus on the synthesis of amoxicillin by the reaction of p-OH-phenylglycine methyl ester and 6-aminopenicillanic acid, catalyzed by penicillin G acylase immobilized on glyoxyl-agarose, at 25 degrees C and pH 6.5. The reaction was carried on a batch reactor. Three kinetic models of this system were compared: a mechanistic, a semi-empiric, and a hybrid-neural network (NN). A semi-empiric, simplified model with a reasonable number of parameters was initially built-up. It was able to portray many typical process conditions. However, it either underestimated or overestimated the rate of synthesis of amoxicillin when substrates' concentrations were low. A more complex, full-scale mechanistic model that could span all operational conditions was intractable for all practical purposes. Finally, a hybrid model, that coupled artificial neural networks (NN) to mass-balance equations was established, that succeeded in representing all situations of interest. Particularly, the NN could predict with accuracy reaction rates for conditions where the semi-empiric model failed, namely, at low substrate concentrations, a situation that would occur, for instance, at the end of a fed-batch industrial process.

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The benzyl 6-fluoro-penicillanate sulfides 4a, 6a, 7a; and sulfones 6c, 7d were synthesized. The conversion to their free acids 4b, 6b, 6d, 7b, 7e and potassium salts 7c, 7f are described. These acids and salt 7c were evaluated as beta-lactamase inhibitors using beta-lactamase I from Bacillus cereus. The data indicate that substitution of the 6 alpha-hydrogen by a 6 alpha-fluorine atom on 6 beta-bromopenicillanic acid (1), leads to loss of beta-lactamase inhibitory activity. In the case of the isomers 6 beta- and 6 alpha-fluoropenicillanic acids the 6 beta-enantiomer proved to be considerably more potent. Potassium salts of 6 beta-fluoropenicillanate sulfide and sulfone were unstable in solid state and in water solution. The fragmentation of the sulfone in two parts in water solution is consistent with the hydrolytic behavior to the penicillanic acid sulfone (2) with 0.5 N NaOH.

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The beta-lactamase from Shigella flexneri UCSF-129 was irreversible inactivated by 6-beta-iodopenicillanic acid. Only one serine residue was modified, according to the spectra change and the amino acid analyses. A pH variation of 0.3 units was found when the chemically modified enzyme was submitted to isoelectric focusing. The inactivation constant of the fast time course reaction was 0.1 seg-1. Protection of 96% was obtained, using cephradine 2,830 times more concentrated than 6-beta-iodopenicillanic acid. It is suggested that this enzyme belongs to class A, according to Ambler (1980).

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Mostra a biodisponibilidade, a farmacinética, a atividade in vitro, os estudos clínicos, a segurança, os efeitos colaterias, a posologia e a relação custo/benfício da junção da pipericilina sódica com a tazobactama sódica

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Mostra a biodisponibilidade, a farmacinética, a atividade in vitro, os estudos clínicos, a segurança, os efeitos colaterias, a posologia e a relação custo/benfício da junção da pipericilina sódica com a tazobactama sódica

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