Aspartate analysis in formulations using a new enzyme sensor

A biosensor has been developed for the purpose of directly analysing aspartate in pharmaceutical formulations and aspartame in sweeteners. This biosensor consists of an ammonia-sensitive gas-diffusion electrode and the enzyme L-aspartase immobilized by means of polyazetidine on a dialysis membrane.     

Electrolytic preparation of an isomer pair of cobalt (III) mixed complexes

The electrolytic preparation of some coordination compounds of cobalt (III), such as the amino-, sulphato- and acetato-complexes, had already been described [1–5]: the presence of the ligand in the electrolysed solution stabilizes the + 3 oxidation state of cobalt, which is generated anodically. All the cobalt (III) complexes prepared up to date by electrochemical methods contain various numbers of the same ligand group, without having regard to the coordinated water molecules. In this note we deal with the electrolytic preparation of two mixed complexes of cobalt (III),cis- andtrans-[Co en₂ (OCOCH₃)₂]ClO₄, where en=ethylenediamine.Work carrid out with the aid of C.N.R. (Consiglio Nazionale delle Ricerche).     

Update on genetics of Huntington''s disease: availability of direct and accurate predictive test

Recently, human leukocyte elastase has been detected in human eosinophils. Reinvestigating these findings, 2.5 pg active human leukocyte elastase (E.C. 3.4.21.37) were found per neutrophil isolated from peripheral blood, whereas the elastase activity of eosinophil preparations was linearly correlated with the content of contaminating neutrophils. Also spontaneous or stimulated release of active elastase was absent in eosinophils. By immunohistochemistry no elastase immunoreactivity could be demonstrated in human eosinophils. Therefore, we conclude that human eosinophils do not contain considerable amounts of human leukocyte elastase.     

Grain refinement induced by electromagnetic stirring: A dendrite fragmentation criterion

The influence of electromagnetic stirring (EMS) on grain refinement has been studied for two copper-base alloys (Cu-1 wt pct Ni-1 wt pct Pb-0.2 wt pct P and Cu-4 wt pct Zn-4 wt pct Sn-4 wt pct Pb) solidified in a Bridgman furnace. Metallographic inspection of the specimens, temperature measurements during solidification, and numerical simulations performed with CALCOSOFT revealed that the efficiency of EMS is strongly dependent upon the penetration of the liquid in the mushy zone and therefore upon the position of the convection vortices with respect to the liquidus front. In particular, the low-concentration alloy could be grain refined only at high power and when the coil was moved close to the liquidus front. These results were analyzed on the basis of a dendrite fragmentation criterion similar to Flemings’ criterion for local remelting of the mushy zone. Considering that the component of the fluid flow velocity along the thermal gradient, , must be larger than the casting speed, V _c , dendrite fragmentation occurs if

Reduction of hexavalent chromium by H2O2 in acidic solutions

The rates of the reduction of Cr(VI) with H2O2 were measured in NaCl solutions as a function of pH (1.5-4.8), temperature (5-40 degrees C), and ionic strength (I = 0.01-2 M) in the presence of an excess of reductant. The rate of Cr(VI) reduction is described by the general expression -d[Cr(VI)]/dt = k2[Cr(VI)](m)[H2O2](n)[H+](z), where m = 1 and n and z are two interdependent variables. The value of n is a function of pH between 2 and 4 (n = (3 x 10(a))/(1 + 10(a)), where a = -0.25 - 0.58pH + 0.26pH2) leveling off at pH < 2 (where n approximately = 1) and pH > 4 (where n approximately = 3). The rates of Cr(VI) reduction are acid-catalyzed, and the kinetic order z varies from about 1.8-0.5 with increasing H2O2 concentration, according to the equation z = 1.85 - 350.1H2O2 (M) which is valid for [H2O2] < 0.004 M. The values of k2 (M(-(n+z)) min(-1)) are given by k2 = k/[H+](z) = k1/[H2O2](n)[H+](z), where k is the overall rate constant (M(-n) min(-1)) and k, is the pseudo-first-order rate constant (min(-1)). The values of k in the pH range 2-4 have been fitted to the equation log k = 2.14pH - 2.81 with sigma = +/- 0.18. The values of k2 are dependent on pH as well. Most of the results with H2O2 < 3 mM are described by log k2 = 2.87pH - 0.55 with sigma = +/- 0.54. Experimental results suggest that the reduction of Cr(VI) to Cr(III) is controlled by the formation of Cr(V) intermediates. Values of k2 and k calculated from the above equations can be used to evaluate the rates of the reaction in acidic solutions under a wide range of experimental conditions, because the rates are independent of ionic strength, temperature, major ions, and micromolar levels of trace metals (Cu2+, Ni2+, Pb2+). The application of this rate law to environmental conditions suggests that this reaction may have a role in acidic solutions (aerosols and fog droplets) in the presence of high micromolar concentrations of H2O2.     

短链葡聚糖包合姜黄素的分子机制

通过利用普鲁兰酶来酶解蜡质玉米淀粉而得到的短链葡聚糖来包合姜黄素,可以极大地提高姜黄素的水溶性。本研究还使用新型的计算机模拟的方法来分析短链葡聚糖和姜黄素的包合行为机制,模拟了短链葡聚糖-姜黄素包合物在600 ns内的分子包合行为。从模拟轨迹中获取的自组装快照图,可以知道包合物的结合方式是边解离边复合最后趋于稳定结构的包合方式。通过体系回转半径反应了短链葡聚糖随着时间与姜黄素包合行为过程中的构象变化,结果与快照图一致。体系溶解性较好,模拟得知的结果与实验基本一致,短链葡聚糖-姜黄素的溶解性高于单独的姜黄素水溶液,提高了姜黄素的生物利用率。为医学领域寻找合适的药物壁材提供了一种新的研究途径。     

Low-grade fever of protracted course. Retrospective study of 30 cases and reflections for a low-cost management

The objects of this paper were the following: 1) to establish in a group of persistent (over four weeks) low grade fever (LGF) patients the percentage of cases in which a definite diagnosis could not be made; 2) where a definite diagnosis could be made, to describe the most commonly occurring diseases; 3) to follow up the uncertain diagnosis cases for at least two years. Thirty cases of persistent LGF were retrospectively studied. They did not include drug hyper-dysthermia and temporary and/or metabolic vasomotor reactions. The data suggest that: 1) two thirds of persistent LGF are likely not to be definitely diagnosed; 2) some certain diagnoses were: dental granulomas, mycobacteria infections, thyroiditis, factitious fever, rheumatic polymyalgia, Hodgkin's lymphoma and pulmonary thromboembolism; 3) in 14/19 undiagnosed cases the fever subsided permanently, without any treatment, within one year, whereas it persisted in 5/19, but no deterioration of the overall clinical status was observed; 4) although some of the undiagnosed cases were examined elsewhere, a certain diagnosis was never achieved in spite of their undergoing sophisticated and expensive clinical, laboratory and X-ray tests. Therefore it is concluded that: 1) persistent LGF should be managed more conservatively than fever of unknown origin so as to preserve resources; 2) some diseases should be included in the differential diagnoses from the beginning of the initial clinical work up; 3) undiagnosed LGF fever either subsides and returns to normal within one year or the fever persists, but no deterioration of the clinical and performance status is likely to occur.