Investigation of the monomeric and oligomeric molecular forms of human growth hormone and poly-L-lysine using fluorescence anisotropy measurement method

Summary This work illustrates the usefulness of fluorescence anisotropy measurement using a long-lifetime fluorescence label bis-(bipyridine)-5-(isothiocyanatophenanthrolin)-Ru(PF^6-)₂ for the investigation of large macromolecules - human growth hormone forms with different aggregation degree and poly-L-lysine hydrobromides with different molecular weights. Three molecular forms of this hormone – monomeric and two oligomeric (with polymerization degree 3 and 5) – and poly-L-lysine hydrobromides with different molecular weights were for the first time investigated using fluorescence anisotropy measurement by the constant viscosity. Fluorescence anisotropy and rotational correlation time are determined for each substance. Calculated rotational correlation times in investigated media are linear proportional to polymerization degree of molecular forms of the hormone. Relationship between rotational correlation time and molecular weight of random coil structure poly-L-lysines (with similar molecular weights) is nonlinear. It was shown what measured fluorescence anisotropy of the simple mixtures of two labeled molecular forms of the hormone well corresponds with theoretical anisotropy calculated with average values of the anisotropies of the separately investigated pure compounds.     

Modification of Ca2+, Mg2+-ATPase and F-actin distribution in hepatocytes of cyclosporine A treated rats. Effect of soyabean lecithin and triacylglycerol

Two oligodeoxynucleotide (oligodN) binding proteins of 100-110 kDa on plasma membranes of human cell lines were recently identified by us. These two proteins seemed to play a role in oligodN uptake. In this study, the impact of the chain length and the sequence of the oligodN on the interaction with those two proteins was investigated. Chain length of oligodN was an important determinant, but not the sole determinant for the interaction. Binding affinity of oligodNs was determined predominantly by base composition, where pyrimidine bases but not purine bases were required in the sequence to retain high affinity. The binding kinetics of the homopolymers of deoxycytidine (dC21) and deoxythymidine (dT21) suggests that the proteins may have different binding sites, with one site preferring thymine bases and the other cytosine bases. Moreover, some additional plasma membrane proteins were identified, with an apparent molecular mass ranging from 40 to 58 kDa, which could bind thymine bases but not cytosine bases.     

类Henon吸引子动力学演化研究

给Henon吸引子系统引入正弦因子，提出了类Henon吸引子的一种模型，研究其在相位控制参数下的混沌演化行为。     

Parallel increase in carotid, brachial and left ventricular cross-sectional areas in arterial hypertension

Few data have been published about the relation between the vessels geometry and development of left ventricular (LV) hypertrophy in patients with arterial hypertension. The aim of this study is to describe arterial and LV geometry changes due to mild-to-moderate arterial hypertension in an untreated hypertensive population. In 95 untreated patients with mild-to-moderate hypertension and 23 age- and sex-matched healthy normotensives, we measured the end-diastolic diameter and wall thickness of the left ventricle and the internal diameter and intimal-medial thickness (IMT) of carotid and brachial arteries. From these data, the cross-sectional areas (CSAs) of arterial and myocardial walls were calculated. Hypertensive patients were further subdivided on the basis of the presence of LV hypertrophy defined according to Devereux et al as anatomical LV mass >125 g/m. In hypertensive patients with hypertrophy, carotid and brachial CSAs increased, without significant changes in thickness/diameter ratio (arterial 'enlargement'), while the left ventricle developed 'concentric' hypertrophy. Arterial and LV CSAs showed a significant direct correlation with systolic blood pressure (BP). However, when data were corrected for BP, the correlation between the increase in arterial and LV CSAs became much improved than for the raw data. In conclusion patients with untreated mild-to-moderate hypertension, both carotid and brachial arterial walls showed an enlargement that was proportional to the development of LV hypertrophy. These results suggest that the effects of arterial hypertension on carotid, brachial and LV wall geometry have a common modulation.     

Preparation and properties of poly(L‐lactic acid) scaffolds by thermally induced phase separation from a ternary polymer–solvent system

Poly(L ‐lactic acid) (PLLA) foams for tissue engineering were prepared via thermally induced phase separation of a ternary system PLLA/dioxane/tetrahydrofuran (THF) followed by double solvent exchange (water and ethyl alcohol) and drying. An extension to solidification from solution of a previously developed method for solidification from the melt was adopted. The technique is based on a continuous cooling transformation (CCT) approach, consisting in recording the thermal history experienced by rapidly cooled samples and then analyzing the resulting sample morphology. Different foams were produced by changing the relative amount of dioxane and THF in the starting solution while the amount of polymer was kept constant. Results show that the final morphology and crystallinity (measured by DSC) depend on solvent power, which in its turn was determined by the ratio dioxane/THF, and a minimum of pore size, optimum final crystallinity and crystallization rate were achieved for a system containing 70 % of dioxane. Under this condition, a higher bulk density (evaluated by Hg intrusion porosimetry) and a larger specific surface area (measured by BET N₂ sorption technique) was achieved. Copyright © 2004 Society of Chemical Industry     

Emulsion copolymerization of vinyl esters in continuous reactors: Comparison between loop and continuous stirred tank reactors

The high solids emulsion copolymerization of vinyl acetate and veova 10 was studied in a continuous loop reactor and in a continuous stirred tank reactor (CSTR) in an attempt to elucidate the similarities and differences between these reactors. Reactions were carried out under comparable conditions, namely, similar macromixing and the same feed composition and space time. The behavior of both reactors was almost the same when the heat generation rate was low; otherwise, thermal runaway occurred in the CSTR whereas the loop reactor temperature was easily controlled. © 1995 John Wiley & Sons, Inc.     

食品防腐剂山梨酸的快速测定法

本法采用三氯甲烷从样品中直接一次提取山梨酸，再以碳酸氢钠一次反萃取净化，在２５４ｎｍ，处直接测定样品吸光 与标准进行比较定量，可快速得到测定结果，此法具有操作简便，快速，测定精密度高的特点，适用于水果汁，果酱，罐头，软饮料等食品中山梨酸及其钾盐的快速测定。     

Survival motor neuron (SMN) protein in rat is expressed as different molecular forms and is developmentally regulated

Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by a progressive degeneration of motoneurons in spinal cord and brainstem. The telomeric copy of a duplicated gene termed survival motor neuron (smn), which maps to chromosome 5q13, has been found to be deleted in most patients. The encoded gene product is a novel protein which recently has been shown to accumulate in specific nuclear organelles (gemini of coiled bodies, GEMS), and to play a part in the formation of the spliceosome complex. We have cloned and sequenced the rat smn cDNA. Antibodies generated against an N-terminus peptide recognized a main protein of 32 kDa in immunoblots of rat embryonic tissue extracts. Minor bands of 35 kDa, 45 kDa and, in perinatal muscle, of 24 kDa were also specifically detected, indicating that SMN is expressed as different molecular forms. Subcellular fractionation indicated that the 32 kDa form is mainly soluble, while the 35 kDa and 45 kDa products segregate to the microsomal-mitochondrial fraction. SMN protein is highly regulated during development: expression is high in embryonic tissues (central nervous system, muscle, lung and liver), and then progressively decreases to very low levels in most tissues of the adult. The demonstration of different molecular forms of SMN along with its developmental regulation may help to understand the contribution of this protein in the appearance of SMA phenotype.