苯乙烯-异戊二烯嵌段共聚物分子运动的脉冲核磁共振研究

用西德Bruke,MSL-300核磁共振谱仪研究了三个不同系列的苯乙烯-异戊二烯嵌段共聚物的固体回波谱。用PASCAL语言在谱仪提供的计算机上、用线性最小二乘法回归分析把实验曲线分解成快速和慢速两个组分,它们分别对应于嵌段共聚物中刚性相和流动相,从而给出样品两相结构的定性定量信息。     

The development and validation of a novel LC–MS/MS method for the quantification of cenicriviroc in human plasma and cerebrospinal fluid

A high-performance liquid chromatography tandem mass spectrometric method was developed and validated for cenicriviroc (CVC) quantification in human plasma and cerebrospinal fluid (CSF). The method involved precipitation with acetonitrile and injecting supernatants onto the column. Separation was achieved on an XBridge C₁₈ column with a gradient elution of 0.1% formic acid in water and acetonitrile. Analyte detection was conducted in positive ion mode using selected reaction monitoring. The m/z transitions were: CVC (697.3 → 574.3) and CVC-d7 (704.4 → 574.3). Calibration curve ranged from 5 to 1000 ng/mL for plasma and from 0.241 to 15.0 ng/mL for CSF. The intra- and inter-day precision and accuracy were <15% for both plasma and CSF across four different concentrations. CVC recovery from plasma and artificial CSF was >90%. The method was utilized for the measurement of patients’ plasma and CSF samples taking a dose of 50, 150 and 300 mg q.d.     

Determination of trace elements in a human serum reference material by inductively coupled plasma mass spectrometry

A method was developed for the determination of Fe, Co, Cu, Zn, Rb, Mo and Cs in human serum by ICP-MS. Sample preparation was kept as limited as possible: Serum samples were diluted with nitric acid and indium was added as internal standard. The results for Fe, Co, Cu, and Zn were corrected for interferences from polyatomic ions using a suitable blank solution. No interferences occur for the considered isotopes of Rb, Mo, and Cs. A second-generation human serum reference material was analyzed, in order to test the accuracy and precision of the analytical procedure. The results obtained are in good agreement with the certified values.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, AustriaResearch Director of the National Fund for Scientific Research (Belgium)     

INTERNALIZATION OF GAP JUNCTIONS BETWEEN NEURON AND GLIAL CELL AND FORMATION OF ANNULAR LAMELLAR BODIES IN CHINESE LEECH Whitmania pigra

This paper reveals the formation of annular lamellar body (ALB) in the ganglion of leech by means of in situ fixation and the lanthanum nitrate tracer technique. This formation involves both wrapping and internalization of the gap junctions between glial processes themselves, as well as between neuron and glial process. The results indicate that there is probably an active process of internalization of membrane structures involving gap junctions between neuron and glial cell in the central nervous system in leech. The functions of ALB are discussed.     

IDENTIFICATION OF PARTIAL MUTATIONAL SITES IN HUMAN MITOCHONDRIAL DNA IN THE CHINESE AND ITS SIGNIFICANCE

A simple method for the identification of mutational sites in human mitochondrial DNA (mtDNA) was described. It was based on the human Cambridge sequence as a relative standard sequence and a single base pair substitution in mtDNA as a unique mutational form. The partial mutational sites can be determined using this method which was characterized by combining the restriction mapping with the analysis for the table of human mtDNA potential mutational sites with rapidity and simplicity. In the meanwhile, six mtDNA mutational sites found in Chinese population were identified by means of this method.     

Calix[4]arenes as Molecular Platforms for Magnetic Resonance Imaging (MRI) Contrast Agents

The novel amphipilic conjugate of a calix[4]arene with four Gd–1,4,7,10‐ tetra(carboxymethyl)‐1,4,7,10‐tetraazacyclododecane (DOTA) chelates has potential as a magnetic resonance imaging contrast agent, both in its monomeric and in its micellar form. The system, illustrated here with its nuclear magnetic relaxation profile, shows good relaxivities, thanks to its high rigidity.

     

Optical probes for detection and quantification of neutrophils’ oxidative burst. A review

Neutrophils, also known as polymorphonuclear leukocytes (PMN), are the most common type of white blood cells, comprising about 50-70% of all white blood cells. In the event of inflammatory processes, neutrophils display increased mobility, tissue influx ability, prolonged life span, and an increased phagocytic capacity, constituting the initial participants in the cellular defense of the organism. One of the most important defense systems of neutrophils corresponds to their ability to mediate a strong oxidative burst through the formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). While oxidative burst is important for the elimination of invading microorganisms, the overproduction of ROS and RNS or the impairment of endogenous antioxidant defenses may result to detrimental effects to the host. The nature and the extent of ROS and RNS production by neutrophils in response to different stimuli is, consequently, a matter of extensive research, with scientific reports showing an enormous variability on the detection methodologies employed. This review attempts to provide a critical assessment of the most common approaches to identify and quantify reactive species formed during the neutrophils’ oxidative burst. The detection mechanisms and performance, as well as advantages and limitations of the different methodologies, are scrutinized, focusing on the use of fluorimetric, chemiluminometric and colorimetric probes.