Benzothiadiazole as an Inducer of β-1,3-Glucanase and Chitinase Isozymes in Sugar Beet

The effect of benzothiadiazole (BTH) on protein synthesis was studied in sugar beet plants. Extracellular proteins induced by 0.025 % BTH were examined and their pattern was compared with that induced by sodium salicylate, chitosan, paraquat, AgNO₃, and by tobacco necrosis virus. BTH induced synthesis of at least 9 acidic and 6 basic proteins; three of them appeared as acidic chitinase isozymes, three as acidic β-1,3-glucanase isozymes, three as basic chitinase isozymes, and one as a basic β-1,3-glucanase isozyme. One of the basic chitinase isozymes was found also in control plants. The most of the newly formed proteins was also induced by the other inducers under study regardless of the necrotic or symptomless reaction of plants. The benzothiadiazole proved to be an efficient inducer of proteins in sugar beet. This revised version was published online in July 2006 with corrections to the Cover Date.     

Encapsulation of rat hepatocyte spheroids for the development of artificial liver

Hepatocyte spheroids and hepatocyte were immobilized in chitosan/alginate capsules formed by the electrostatic interactions between chitosan and alginate. After encapsulation, there was a 10% decrease in the viability of spheroids due to the exposure of the cells to a pH 6 during the encapsulation process. However, the encapsulated hepatocyte spheroids maintained over 50% viability and liver specific functions for 2 weeks while the encapsulated hepatocytes, free hepatocytes and free hepatocyte spheroids showed low viability and liver specific functions. Therefore, encapsulated hepatocyte spheroid might be applied to the development of a bioartificial liver.     

A simple microcapsule generator design for islet encapsulation

Techniques for immunoisolation and immobilization of viable cells within semipermeable microcapsules have been developed using highly sophisticated droplet generator systems. We propose here an indigenously designed, simple and efficient droplet generator system for encapsulation of the pancreatic islets employing chitosanalginate matrix. The droplet generator system comprises of a needle assembly, a 3-way valve with extended rubber tubing and a filtration unit connected to a pressure pump. Microbeads of the size of around 400 μm diameter or even lesser (minimun attainable size 20.2 μm) could be easily generated using the droplet generator system proposed here. Islet microcapsules cultured in Roswell Park Memorial Institute (RPMI) 1640 with 10% fetal calf serum showed around 98% viability, comparable to that of the non-encapsulated islets. Transplantation of microencapsulated islets to streptozotocin (STZ)-induced diabetic mice, resulted in disappearance of hyperglycemia and restoration of normoglycaemia during a 30-day follow-up suggesting graft functionality. No graft failures were observed in any of the transplanted mice (n = 15) and none of them showed membrane associated fibrous overgrowth, which can be attributed to the fibroblast-growth inhibitory properties of chitosan. The proposed design appears to be superior in its simplicity and cost effectiveness and comparable in performance with the microcapsule generator designs proposed so far. The proposed system can be further exploited for encapsulation and immunoisolation of various cell types in alginate based matrices.     

壳聚糖对几种植物病原真菌的作用

在马铃薯葡萄糖琼脂 ( PDA)上测定了酸溶性壳聚糖 ( S- )和 2种水溶性壳聚糖 ( S- 和 S- )对 15种植物病原真菌的作用 ,结果表明 ,三种壳聚糖对供试的 15种植物病原真菌均有一定程度的抑制作用 ,抑制强度因壳聚糖的理化性质以及不同的病原真菌而有较大差异。水溶性壳聚糖 S- 可明显抑制水稻恶苗病菌分生孢子的萌发。壳聚糖的抑菌作用机制与其增加菌丝细胞膜的透性有关。     

通过研究改性壳聚糖与细胞的相互作用评价其生物相容性

利用细胞生物学的方法, 研究了四种不同的细胞在经过改性的壳聚糖（ＣＨＩＴＯＳＡＮ） 膜上的生长,测定了细胞相对黏附力、细胞初始黏附率, 并利用ＦＤＡ 实验测定了细胞活力,从而从多个方面评价了这几种不同材料的生物相容性。实验结果表明,与明胶交联的壳聚糖膜明显比其它两种膜有利于细胞的黏附和生长,为进一步对材料进行筛选奠定了基础。     

Biosynthesis of Al2O3 and europium-doped Al2O3 nanoparticle using Cymbopogon citratus (lemongrass) extract and its antibacterial property

Cymbopogon citratus-mediated pure aluminium oxide (Al₂O₃) and europium (Eu)-doped Al₂O₃ with different amounts of metal ion were prepared using a green synthesis method. Synthesised nanoparticles were characterised by ultraviolet (UV)-visible spectroscopy, photoluminescence (PL), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Synthesis of nanoparticles is confirmed by using UV-visible spectroscopy showing maximum absorption at 411 and 345 nm for Al₂O₃ and Eu-doped Al₂O₃, respectively. The antibacterial activity of prepared nanoparticles was evaluated against Pseudomonas aeruginosa, Streptococcus aureus, Escherichia coli and Klebsiella pneumoniae using a well-diffusion technique. The effect of pure Al₂O₃ and Eu-doped nanoparticles shows excellent results against P. aeruginosa, S. aureus, E. coli and K. pneumoniae.     

Synthesis of hydroxyethyl starch 200/0.5-loaded albumin nanoparticles: biocompatibility and interaction mechanism

We aimed to synthesize hydroxyethyl starch (HES) 200/0.5-loaded bovine serum albumin nanoparticles (HBNs) and investigate the compatibility and binding mechanism in simulated physiological environments. Here, to elucidate the morphology, biocompatibility, and formation mechanism of HBNs, techniques such as scanning electron microscopy, haemolysis test, fluorescence, and circular dichroism spectroscopy were applied. The thermodynamic parameters at body temperature (ΔS° = −26.7 J·mol⁻¹·K⁻¹, ΔH° = −3.20 × 10⁴ J·mol⁻¹, and ΔG = −2.35 × 10⁴ J·mol⁻¹) showed a 1:1 binding stoichiometry, which was formed by hydrogen bonds and van der Waals interactions. In addition, the conformational analysis showed that the microenvironment of fluorophores was altered with the adaptational protein secondary structural changes. Energy transfer occurred from the fluorophores to HES with a high possibility. All these results provided accurate and complete primary data for demonstrating the interaction mechanisms of HES with BSA, which helps to understand its pharmaceutical effects in blood.     

Amelioration of indole acetic acid-induced cytotoxicity in mice using zinc nanoparticles biosynthesized with Ochradenus arabicus leaf extract

The diversity of natural phytochemicals represents an unlimited source for discovery and development of new drugs. Ochradenus arabicus, (family: Resedaceae) a notable medicinal plant displays a high content of flavonoid glycosides. This study investigates a possible preventative role of zinc nanoparticles biosynthesized by O. arabicus leaf extracts (OAZnO NPs) in limiting genotoxicity and cytotoxicity caused by indole acetic acid (IAA) in laboratory mice. ZnO NPs were synthesized using O. arabicus leaf extracts and characterized with UV–visible spectroscopy, scanning electron microscopy (SEM) and X-Ray diffraction (XRD). The mice were randomly distributed into the following six groups: control, OAZnO NPs treated (10 mg/kg BW), IAA treated (50 mg/kg BW); simultaneous treatment, pre-treatment, and post-treatment. Reactive oxygen species (ROS), DNA damage, chromosome aberration, and apoptosis were analyzed as toxicity endpoints. IAA exposure significantly induced production of ROS, DNA damage, apoptosis, chromosome aberrations, and micronuclei. Pre-, post-, and simultaneous treatment with OAZnO NPs ameliorated the damage caused by IAA exposure. Exposure to OAZnO NPs alone caused no toxicity for any endpoint based on comparison to controls. This study demonstrated that IAA-induced cytotoxic damage in mice could be ameliorated by treatment with OAZnO NPs. These findings require additional verification in mechanistic and in vitro studies.     

Chitosan magnetic nanoparticles for drug delivery systems

The potential of magnetic nanoparticles (MNPs) in drug delivery systems (DDSs) is mainly related to its magnetic core and surface coating. These coatings can eliminate or minimize their aggregation under physiological conditions. Also, they can provide functional groups for bioconjugation to anticancer drugs and/or targeted ligands. Chitosan, as a derivative of chitin, is an attractive natural biopolymer from renewable resources with the presence of reactive amino and hydroxyl functional groups in its structure. Chitosan nanoparticles (NPs), due to their huge surface to volume ratio as compared to the chitosan in its bulk form, have outstanding physico-chemical, antimicrobial and biological properties. These unique properties make chitosan NPs a promising biopolymer for the application of DDSs. In this review, the current state and challenges for the application magnetic chitosan NPs in drug delivery systems were investigated. The present review also revisits the limitations and commercial impediments to provide insight for future works.     

Potato bacterial wilt suppression and plant health improvement after application of different antioxidants

Bacterial wilt caused by Ralstonia solanacearum is a devastating disease that often threatens potato production and exportation. The potential of four antioxidants (seaweed extract (SWE), yeast, chitosan and ascorbic acid (ASA)) in controlling the disease was evaluated in vitro, under glasshouse and field conditions. The field experiment was conducted in two naturally infested locations: Wardan, Giza (sandy soil), and Talia, Minufiya (silty clay soil). Only chitosan showed antibacterial properties against the pathogen in vitro. SWE, yeast and chitosan showed disease suppression under both glasshouse and field conditions. The disease suppression was accompanied by an increase in the ratio of soil copiotrophic to oligotrophic bacteria. The three antioxidants increased plant nitrogen content, decreased soil OM content and decreased C/N ratio. Disease suppression after chitosan application was clearly observed only in Wardan area, which was characterized by a higher soil alkalinity. A high percentage of antagonistic fluorescent strains similar to Pseudomonas putida group were detected for chitosan‐treated plants in Wardan area (sandy soil). ASA drastically decreased the count of the pathogen in soil, but was conducive to the pathogen in plant tissues. A remarkable increase in microbial (bacterial and fungal) soil and rhizosphere diversity as indicated by PCR‐DGGE analysis for bacterial 16S rRNA and fungal 18S rRNA was recorded. In Talia area (silty clay soil), the soil microbial community was more stable and was in general resistant to the disease where the soils were characterized by high electrical conductivity. SWE, yeast and ASA significantly increased crop production in Talia area only.