Technological characterization of Lactobacillus isolates from traditional Manchego cheese for potential use as adjunct starter cultures

Thirty Lactobacillus isolates from artisanal Manchego cheeses, 10 belonging to Lactobacillus plantarum and 20 belonging to Lactobacillus paracasei subsp. paracasei, were examined for potential use as adjunct cultures. Isolates were screened for acidifying and amino-biogenic capacity, for proteolytic, lipolytic, autolytic and aminopeptidase activities, and for sensory characteristics in UHT coagulated milk. Most of the lactobacilli displayed high aminopeptidase and autolytic activities and low acidifying activity. Only one isolate was able to produce tyramine. When growing on milk 53.3% of the Lb. paracasei subsp. paracasei isolates were able to produce pleasant flavours. Strains PBL210 (Lb. plantarum) and PBL213 and PBL226 (Lb. paracasei subsp. paracasei) presented the best technological characteristics, and also were still viable and with unaltered properties after freeze-drying and storage for 12 months. For these reasons, these strains could be good candidates for inclusion as adjuncts in a starter culture to manufacture industrial Manchego cheese.     

Activity and Tissue Expression of Tyrosine Phosphatase PTP-MEG2

Protein tyrosine phosphatases(PTPs) are crucial regulators of signal transduction. Among them,PTP-MEG2 is an intracellular enzyme of 593 amino acid residues with a putative lipid-binding domain at the N-terminus. In the present study, we cloned the full-length form of the enzyme and expressed it in E. coli cells as a 6xHis-tagged protein. The majority of the expressed enzyme was found in the inclusion body of E. coli cell extracts.Upon extraction with a buffer containing urea, the recombinant enzyme was purified to near homogeneity on a single Ni-NTA-agarose column. This procedure resulted in the production of over 100 mg of purified recombinant PTP-MEG2 from 1 L E. coli cell culture. The purified protein displayed a single polypeptide band with expected molecular size on SDS-polyacrylamide gel electrophoresis under reducing conditions. Isolated under denatured conditions in urea, the purified enzyme was re-natured by dialyzing against a refolding buffer. The re-natured enzyme effectively dephosphorylated the common PTP substrate para-nitrophenylphosphate with a specific activity of 2000units/mg. Meanwhile, the denatured enzyme was used to immunize a rabbit to produce antibodies. The resulting antiserum had extremely high sensitivity and specificity. When used for Western blot analysis, the anti-serum revealed a wide expression of PTP-MEG2 in many tissues of mice. Together, we developed a highly effective way to purify a large amount of PTP-MEG2 and generated highly sensitive antibodies that can specifically detect endogenous expression of the enzyme in tissues.     

Batch and continuous studies on treatment of pulp mill wastewater by Aeromonas formicans

Batch and continuous studies have been conducted on the treatment of black liquor from a kraft pulp and paper mill by a bacterial strain, Aeromonas formicans. The results of batch studies revealed that the strain was able to remove 71% and 78% of COD and lignin respectively, while the colour removal efficiency was around 86% in 10 days of retention time. The analysis of lignin degradation products by gas chromatography after 20 days of incubation revealed the formation of some phenolic acids, which were responsible for the decrease in pH during batch studies. The removal efficiencies of COD, colour and lignin obtained in continuous reactor studies were 73, 88 and 77% respectively for an 8 day detention period and these efficiencies were almost the same as obtained in batch studies. © 2001 Society of Chemical Industry     

Polymers used to influence cell fate in 3D geometry: New trends

The extracellular matrix (ECM) is a hydrogel-like structure comprised of several different biopolymers, encompassing a wide range of biological, chemical, and mechanical properties. The composition, organization, and assembly of the ECM play a critical role in cell function. Cellular behavior is guided by interactions that occur between cells and their local microenvironment, and this interrelationship plays a significant role in determining physiological functions. Bioengineering approaches have been developed to mimic native tissue microenvironments by fabricating novel bioactive hydrogel scaffolds. This review explores material designs and fabrication approaches that are guiding the design of hydrogels as tissue engineered scaffolds. As the fundamental biology of the cellular microenvironment is often the inspiration for material design, the review focuses on modifications to control bioactive cues such as adhesion molecules and growth factors, and summarizes the current applications of biomimetic scaffolds that have been used in vitro as well as in vivo.     

Synthesis, properties and biomedical applications of poly(glycerol sebacate) (PGS): A review

Poly(glycerol sebacate) (PGS) is a biodegradable polymer increasingly used in a variety of biomedical applications. This polyester is prepared by polycondensation of glycerol and sebacic acid. PGS exhibits biocompatibility and biodegradability, both highly relevant properties in biomedical applications. PGS also involves cost effective production with the possibility of up scaling to industrial production. In addition, the mechanical properties and degradation kinetics of PGS can be tailored to match the requirements of intended applications by controlling curing time, curing temperature, reactants concentration and the degree of acrylation in acrylated PGS. Because of the flexible and elastomeric nature of PGS, its biomedical applications have mainly targeted soft tissue replacement and the engineering of soft tissues, such as cardiac muscle, blood, nerve, cartilage and retina. However, applications of PGS are being expanded to include drug delivery, tissue adhesive and hard tissue (i.e., bone) regeneration. The design and fabrication of PGS based devices for applications that mimic native physiological conditions are also being pursued. Novel designs range from accordion-like honeycomb structures for cardiac patches, gecko-like surfaces for tissue adhesives to PGS (nano) fibers for extra cellular matrix (ECM) like constructs; new design avenues are being investigated to meet the ever growing demand for replacement tissues and organs. In less than a decade PGS has become a material of great scrutiny and interest by the biomedical research community. In this review we consolidate the valuable existing knowledge in the fields of synthesis, properties and biomedical applications of PGS and PGS-related biomaterials and devices.     

Growth and differentiation potentials in confluent state of culture of human skeletal muscle myoblasts

The transitional behaviors of myoblasts toward differentiation were investigated in the cultures at the low and high seeding densities (respectively, X₀ = 1.0 × 10³ and 2.0 × 10⁵ cells/cm²). In the culture at the low seeding density, an increase in confluence degree accompanied a decrease in growth potential (R_p), being R_p = 0.85 and 0.11 at t = 48 and 672 h, respectively. Myoblasts seeded at the high density resulted in the immediate cessation of growth with keeping the low range of R_p = 0.02–0.09 throughout the culture. The reduction of R_p led to the generation of three subpopulations of cells in proliferative, quiescent and differentiated states. Close cell contacts in the confluent state of high seeding culture induced cell quiescence to a higher extent with suppressing differentiation.     

非线性波在动脉内传播的理论

提出了一个新的非线性脉搏波在动脉内传播的理论模型,推导了一个新的血管壁一外周组织系统的非线性运动方程组。这组运动方程与代表血液流动的粘性不可压缩运动的方程、连续方程以及流体和血管壁本构方程相结合,可用数值方法求解非线性脉搏波在动脉内的传播。其数值解包含压力脉搏波、血流速度波和血流量波以及血管壁的波动和变形等。     

中西方文化差异对英语教学的影响

不同的民族有不同的文化,民族文化之间存在着很大的差异,这种差异给文化交流构成了障碍,给英语教学造成了困难。重视文化差异,了解民族习俗是英语教学中不可忽视的问题。     

Controlled delivery of lipophilic agents to cell cultures for in vitro toxicity and biocompatibility assays

Synopsis
In this report, we present a novel method for delivering lipophilic compounds to cell cultures. The delivery system is based on a nanoemulsion stabilized by phospholipids. These nanoemulsions are well tolerated by cell cultures, such as TK6 lymphoblastoid cells and can be used to deliver defined amounts of encapsulated lipophilic compounds into cells.
We measured the growth inhibition of TK6 lymphoblastoid cells caused by different oils, UV-filters and fragrances to determine the biocompatibility or the toxicity of these compounds in simple cell culture experiments. Our data show that the applied nanoemulsion technology is also very suitable to study biological effects of the UV-A-irradiated compounds in cell culture assays.
Résumé
Dans ce compte-rendu, nous présentons une nouvelle méthode pour dispenser des composés lipophiles à des cultures de cellules. Le système de répartition est fondé sur une nanoémulsion stabilisée par des phospholipides. Ces nanoémulsions sont bien tolérées par les cultures cellulaires, comme les cellules lymphoblastoides TK6 et peuvent etre employées pour délivrer des quantités précises de composés lipophiles encapsulés aux cellules.
Nous avons mesuré l'inhibition de la croissance des cellules lymphoblastoides TK6 provoquée par diverses huiles, des filtres UV et des parfums pour déterminer la biocompatibilité ou la toxicité de ces composés par des essais sur de simples cultures de cellules. Nos données montrent que l'utilisation de la technologie des nanoémulsions convient également à l'étude des effects biologiques des composés irradiés par des UVA dans les cultures cellulaires.