Purification and characterization of xylanase from a thermophilic Streptomyces sp. K37.

Extracellular xylanase (EC 3.2.1.8) from Streptomyces sp. K37 was purified 33.53 by ultrafiltration and cation exchange chromatography followed by gel filtration chromatography. The optimum pH and temperature for purified xylanase were found to be pH 6.0 and 60 degrees C. The Km and V(max) values of the purified xylanase were 15.4 mg ml(-1) and 0.67 micromole reducing sugar min(-1) ml(-1). High performance liquid chromatography (HPLC) gel filtration of the purified xylanase eluted xylanase activity as a peak corresponding to the molecular weight of about 24.3 kDa while the molecular weight determined by SDS-PAGE was found to be 26.4 kDa. The purified xylanase of Streptomyces sp. K37 was found to be endoxylanase and non arabinose liberating enzyme and was highly glycosylated (73.97%).

Bioequivalence and pharmacokinetics of chlorpheneramine in healthy human volunteers.

This study was carried out to evaluate the bioavailability of a new regular release tablet formulation of chlorphenamine (CPA) (Histop) relative to a reference formula (Piriton) using 13 human healthy volunteers. Each one received the two formulations as two 4 mg tablets in a two-way double-blind, crossover study. The concentration of CPA was measured with a sensitive high performance liquid chromatography (HPLC). The geometric mean for the area under the curve up to the last concentration (AUC0-t), to infinity (AUC0-oo) and the maximum concentration (Cp max) were 316.5, 315 + 439.8, 431.2 (ngh/ml) and 22, 20.5 (ug/ml) for the test (T) and reference (R) formulations, respectively. The parametric 90% confidence intervals of T/R ratio of the above parameters were within the bioequivalence acceptable range of 80-125%. The mean time to the maximum concentration Tmax (h) were 2.5 and 2.08 for the two formulations respectively and the parametric 90% confidence intervals of the Tmax difference (T-R) were in the range of -0.26-1.14 h, with point estimate of 0.44 h. The two formulations were found to be bioequivalent by the Schuirmann two one-sided t-test. Based on the pharmacokinetic results obtained frequent (ie, Q 4-6 h) CPA daily dosing may not be required particularly for the adults because of its long elimination half-life.

Effect of fluoride application on specular reflectance and stain potential of unfilled and photocured microfilled resin veneering materials.

A laboratory study was conducted to determine the effect of application of four types of fluoride solutions commonly used and administered by dentists on the specular reflectance and staining potential of photocured and regular unfilled resin veneering materials. The fluoride solutions used were: (1) 1.23% acidulated phosphate fluoride gel (APF) gel, (2) 0.4% stannous fluoride gel, (3) 0.2% sodium fluoride solution and (4) .05% sodium fluoride solution. Specular and diffuse reflectance using scanning spectrophotometer were carried out for the fluoride treated samples and the control untreated samples before and after staining. The results revealed that the (APF) gel, produced the highest surface roughness and staining ability followed by the stannous fluoride solution for the both tested veneering materials. The sodium fluoride mouth wash solutions (0.2% and 0.05%) produced the least effect. So, on the bases of these results, caution should be taken in utilization of fluoride treatment in patients with prosthesis containing resin veneering material.