Activity of Lipase and Chitinase Immobilized on Superparamagnetic Particles in a Rotational Magnetic Field

<div><p>We immobilize hydrolases such as lipase and chitinase on superparamagnetic particles, which are subjected to a rotational magnetic field, and measure the activities of the enzymes. We find that the activities of lipase and chitinase increase in the rotational magnetic field compared to those in the absence of a magnetic field and reach maximum at certain frequencies. The present methodology may well be utilized for the design and development of efficient micro reactors and micro total analysis systems (μ-TASs).</p></div

Outline of the experimental system.

<p>Lipase and chitinase molecules are immobilized on superparamagnetic particles, the average diameter and magnetic dipole moment of which are 130 nm and 3.31×10⁻²³ Wb m, by mixing the particles with aqueous solution, in which lipase and chitinase molecules are dispersed. Dc and rotational magnetic fields are generated by modulating the phase of the electric current supplied to each pair of electromagnets using a function generator. The strength of the magnetic field is set at 9.55 kA m⁻¹, which corresponds to a magnetic flux density of 12 mT, and the frequency of the magnetic field is changed; 1, 3, 5, 7, 10 and 30 Hz. The enzyme-substrate reaction experiment is carried out at 25°C for 30 minutes and the enzyme activity is estimated by measuring the absorbance of 410 nm photons.</p

Dependence of the relative activities on the frequency of the external rotational magnetic field.

<p>(a) Lipase. (b) Chitinase. The ordinate axis represents the activity of the enzymes immobilized on particles in a rotational magnetic field, which is normalized by that in the absence of a magnetic field. The diameter of each particle is 130 nm. The strength of the magnetic field is 9.55 kA m⁻¹. The activities increase and become maximum at certain frequencies.</p

Surgical resection for clinical stage I high-grade neuroendocrine carcinoma of the lung

Abstract Background There are few reports about the factor influencing the prognosis of high-grade neuroendocrine carcinoma. In this study, we evaluated surgical outcome of clinical stage I high-grade neuroendocrine carcinoma. Methods Patients who underwent curative surgery for high-grade neuroendocrine tumors of the lung in clinical stage I were included in this study. We retrospectively analyzed 27 consecutive patients. The aim of this study was to clarify the clinical course of the disease after surgery and what factors influence the prognosis. Results Twenty-two patients have small cell carcinoma, and 5 patients have large cell neuroendocrine carcinoma. Patients who could undergo surgery within 60 days after the first visit (p < 0.01) and undergo lobectomy (p < 0.01) and whose pro-gastrin-releasing peptide ≦ 72 pg/ml (p = 0.04) performed good prognosis after surgery. In multivariate analysis, surgery within 60 days and operative procedure were independent factors associated with OS. Conclusion Surgical resection for clinical stage I high-grade neuroendocrine carcinoma of the lung should be performed as early as possible, and better outcome can be obtained with lobectomy than partial resection