Production and rheological characterization of the viscoelastic biopolymer produced by an eel epithelial cell line

The production and the characterization of the viscoelastic biopolymer from an eel epithelial cell line were investigated in this study. The kinetics of the cell growth and the biopolymer production were firstly examined. The rheological information for the biopolymer produced was provided by three modes of viscoelastic measurements, including flow, creep and oscillatory tests. The effect of pH and temperature on the rheological properties of the biopolymer was also evaluated.     

Ionic relationships in some halophytic Iranian Chenopodiaceae and their rhizospheres

Previous studies on the identification of ion relations in halophytes have revealed that many members of Chenopodiaceae accumulate high amounts of sodium and chloride even in soils with low salinity, indicating a typical pattern which is genetically fixed. In this study, we followed up with the question of ion relations in different halophyte species with different photosynthetic pathways and different salt tolerance strategies over a complete growing season. Soil and plant samples from five species Climacoptera turcomanica (Litv.) Botsch. (leaf succulent-C₄), Salicornia persica Akhani subsp. rudshurensis Akhani (stem succulent-C₃), Halimocnemis pilifera Moq. (leaf succulent-C₄), Petrosimonia glauca (Pall.) Bunge (leaf succulent-C₄) and Atriplex verrucifera M. Bieb. (recreto-halophyte-C₃) were collected over a complete growing season from a salt flat 60 km W of Tehran. The contents of main cations (Na⁺, K⁺, Ca²⁺, and Mg²⁺) and chloride were determined in plant and soil samples. Na⁺ and Cl^? concentration in the shoots of two hygro-halophytes Climacoptera turcomanica and Salicornia persica subsp. rudshurensis were constant over the period of the growing season. In contrast, sodium and chloride in the shoots of Halimocnemis pilifera and Petrosimonia glauca showed respectively an increasing and, in the shoots of Atriplex verrucifera, a decreasing, trend. We did not notice any decreasing trend of K⁺ together with increasing trend of Na⁺ in the shoots of the studied species; however K⁺ in the shoots of all examined species was considerably lower than Na⁺ and Cl^?. It was observed that Climacoptera and Salicornia could absorb and retain calcium even in high salinity conditions, while Halimocnemis and Petrosimonia could not. Na⁺, K⁺, Cl^?, Ca²⁺, and Mg²⁺ contents in the shoots of different types of halophytes (stem-succulent, leaf-succulent and excreting halophyte) or different type of photosynthesis (C₃, C₄) are independent of those in their rhizosphere. We concluded that it is controlled by the genetic characteristic of the specific taxon rather than by the environment.     

Constructive improvement of the ultrasonic separation device ADI 1015

The use of the ultrasonic separation deviceis a very important step in the direction forimproving animal cell bioreactor cultures. However,the normal construction of the ultrasonic separationdevice ADI 1015 has an inherent disadvantage inpumping the cell suspension continuously through thedevice by using a peristaltic pump. The cells aretaken out of the reactor and are transported to theside inlet located below the separation chamber of thedevice. This cycling leads to cell death and aconsiderable reduction of the viable cell density. Themodification of the configuration of the device (nocirculation of the cell suspension through theretention device; during approximately 9 minutescell-free supernatant is extracted; every 9 minute forabout one minute, the volume which is equivalent tothe interior volume of the chamber and the tubingconnecting the device to the reactor, is flushed backin order to return the retained cells back to thereactor) allows cell densities from 10⁶ to2.7 × 10⁶ c/ml with a viability of at least90% (tested for the shear sensitive insect cell lineHigh Five), whereas the maximal cell densitiesobtained were 0.76 × 10⁶ c/ml for the periodof continuous culture and 10⁵ c/ml at the end ofthe use of the device in the classical mode.     

Nomenclature of Isoprostanes: A Proposal

The isoprostanes are a new class of natural products produced in vivo by a non-enzymatic free-radical-induced peroxidation of polyunsaturated fatty acid. In the case of arachidonic acid, for example, four classes of isoprostanes can be produced. Because of the specific structural features distinguishing them from other free-radical-generated products, e.g., HETEs, etc., the isoprostanes can provide an exclusive and selective index for the oxidant component of several inflammatory and degenerative diseases. The possible mechanisms of formation of the individual isoprostanes is discussed in detail. Class III products, such as 8-iso-PGF_2α and 8-iso-PGE₂ have been shown to be vasoconstrictors and modulate platelet function. Several synthetic representatives from the four classes of arachidonic-acid-derived isoprostanes have already been prepared by total synthesis. These synthetic standards have been used for the identification and quantitation of these isoprostanes in biological fluids using gas chromatography/mass spectrometry methodology.     

Schriftenschau

Ohne Zusammenfassung     

Stability of 17D Yellow Fever Virus Vaccine Using Different Stabilizers

To optimize the thermostability of lyophilized 17D vaccine, the authors investigated parameters important for the freeze-drying process. Six different stabilizers with different sugars and amino acids were analysed in a freeze-thaw cycle for their crystallization characteristics and their stabilizing effect under thermal treatment conditions of 37 degrees C for 28 days. This test indicated that three out of six stabilizers (B, C, F) kept the vaccine significantly more stable than the three others (A, D, E). Under storing conditions of 4 degrees C over 96 days stabilizers A, B and C produced the lowest decrease in titre of about 10% in contrast to stabilizers D, E and F with a higher decrease in infectivity titre. Analysing the stability of the 17D vaccine using five different reconstitution solutions, we found that 90% D2O shows the best stabilizing effect under thermal treatment of 37 degrees C up to 24 h.