Determination of atorvastatin in human serum by reversed-phase high-performance liquid chromatography with UV detection

A rapid and sensitive high-performance liquid chromatographic method was validated and described for determination of atorvastatin in human serum. Following liquid-liquid extraction of the drug and an internal standard (sodium diclofenac), chromatographic separation was accomplished using C18 analytical column with a mobile phase consisting of sodium phosphate buffer (0.05 M, pH 4.0) and methanol (33:67, v/v). Atorvastatin and the internal standard were detected by ultraviolet absorbance at 247 nm. The average recoveries of the drug and internal standard were 95 and 80%, respectively. The lower limits of detection and quantification were 1 and 4 ng/ml, respectively, and the calibration curves were linear over a concentration range of 4-256 ng/ml of atorvastatin in human serum. The analysis performance was studied and the method was applied in a randomized cross-over bioequivalence study of two different atorvastatin preparations in 12 healthy volunteers.     

The C‐terminal linker of Escherichia coli FtsZ functions as an intrinsically disordered peptide

The tubulin homologue FtsZ provides the cytoskeletal framework and constriction force for bacterial cell division. FtsZ has an ～ 50‐amino‐acid (aa) linker between the protofilament‐forming globular domain and the C‐terminal (Ct) peptide that binds FtsA and ZipA, tethering FtsZ to the membrane. This Ct‐linker is widely divergent across bacterial species and thought to be an intrinsically disordered peptide (IDP). We confirmed that the Ct‐linkers from three bacterial species behaved as IDPs in vitro by circular dichroism and trypsin proteolysis. We made chimeras, swapping the Escherichia coli linker for Ct‐linkers from other bacteria, and even for an unrelated IDP from human α‐adducin. Most substitutions allowed for normal cell division, suggesting that sequence of the IDP did not matter. With few exceptions, almost any sequence appears to work. Length, however, was important: IDPs shorter than 43 or longer than 95 aa had compromised or no function. We conclude that the Ct‐linker functions as a flexible tether between the globular domain of FtsZ in the protofilament, and its attachment to FtsA/ZipA at the membrane. Modelling the Ct‐linker as a worm‐like chain, we predict that it functions as a stiff entropic spring linking the bending protofilaments to the membrane.     

Determination of acyclovir in human serum by high-performance liquid chromatography using liquid-liquid extraction and its application in pharmacokinetic studies

A fast, simple and sensitive high performance liquid chromatographic (HPLC) method has been described for determination of acyclovir in human serum. Since acyclovir is a polar compound and soluble in aqueous medium and practically insoluble in most of organic solvents, its analysis in biological fluids in currently published HPLC methods, involve pre-treatment of acyclovir plasma sample including deproteinization or solid phase extraction. In present method liquid-liquid extraction of acyclovir and internal standard (vanillin) is achieved using dichloromethane-isopropyl alcohol (1:1, v/v) as an extracting solvent. Analysis was carried out on ODS column using methanol-phosphate buffer (0.05 M) containing sodium dodecyl sulfate (200 mg/L) and triethylamine (2 mL/L, v/v) as mobile phase (pH=2.3; 5:95, v/v) at flow rate of 2 ml/min. The method was shown to be selective and linear into the concentration range of 10-2560 ng/mL. Accuracy and precision of the method were also studied. The limit of quantitation was evaluated to be 10 ng/mL. This method was applied in bioequivalence study of two different acyclovir preparations after administration of 400mg in 12 healthy volunteers.     

The myth of plant transformation

Technology development is innovative to many aspects of basic and applied plant transgenic science. Plant genetic engineering has opened new avenues to modify crops, and provided new solutions to solve specific needs. Development of procedures in cell biology to regenerate plants from single cells or organized tissue, and the discovery of novel techniques to transfer genes to plant cells provided the prerequisite for the practical use of genetic engineering in crop modification and improvement. Plant transformation technology has become an adaptable platform for cultivar improvement as well as for studying gene function in plants. This success represents the climax of years of efforts in tissue culture improvement, in transformation techniques and in genetic engineering. Plant transformation vectors and methodologies have been improved to increase the efficiency of transformation and to achieve stable expression of transgenes in plants. This review provides a comprehensive discussion of important issues related to plant transformation as well as advances made in transformation techniques during three decades.     

In vitro characterization of subventricular zone isolated neural stem cells,from adult monkey and rat brain

Neural stem cells (NSCs) are multipotent, self-renewable cells who are capable of differentiating into neurons, astrocytes, and oligodendrocytes. NSCs reside at the subventricular zone (SVZ) of the adult brain permanently to guarantee a lifelong neurogenesis during neural network plasticity or undesirable injuries. Although the specious inaccessibility of adult NSCs niche hampers their in vivo identification, researchers have been seeking ways to optimize adult NSCs isolation, expansion, and differentiation, in vitro. NSCs were isolated from rhesus monkey SVZ, expanded in vitro and then characterized for NSCs-specific markers expression by immunostaining, real-time PCR, flow cytometry, and cell differentiation assessments. Moreover, cell survival as well as self-renewal capacity were evaluated by TUNEL, Live/Dead and colony assays, respectively. In the next step, to validate SVZ-NSCs identity in other species, a similar protocol was applied to isolate NSCs from adult rat’s SVZ as well. Our findings revealed that isolated SVZ-NSCs from both monkey and rat preserve proliferation capacity in at least nine passages as confirmed by Ki67 expression. Additionally, both SVZ-NSCs sources are capable of self-renewal in addition to NESTIN, SOX2, and GFAP expression. The mortality was measured meager with over 95% viability according to TUNEL and Live/Dead assay results. Eventually, the multipotency of SVZ-NSCs appraised authentic after their differentiation into neurons, astrocytes, and oligodendrocytes. In this study, we proposed a reliable method for SVZ-NSCs in vitro maintenance and identification, which, we believe is a promising cell source for therapeutic approach to recover neurological disorders and injuries condition.

     

The roles of matrix molecules in mediating chondrocyte aggregation, attachment, and spreading

The most abundant macromolecules in cartilage are hyaluronan, collagen, aggrecan, and link protein, which are believed to play roles in maintaining a unique three-dimensional network for a functional joint. This study was designed to investigate the roles of the major extracellular molecules in mediating chondrocyte-matrix interactions. We employed specific approaches to remove components individually or in combination: hyaluronan was digested with hyaluronidase; type II collagen was digested with collagenase; aggrecan expression was inhibited with antisense and beta-xyloside approaches; and link protein expression was inhibited with antisense oligonucleotides. Digestion of hyaluronan induced chondrocyte attachment to tissue culture plates, collagen-coated plates, and fibroblast-like chondrocyte cultures, and induced chondrocyte aggregation. Treated chondrocytes exhibited a fibroblast-like morphology, and the effects of hyaluronidase were dose-dependent. Conversely, the effect of collagenase on chondrocyte adhesion and aggregation was far less pronounced. Treatment with Arg-Gly-Asp peptide inhibited chondrocyte-collagen interaction. Chondrocyte attachment was enhanced by antisense oligonucleotides complementary to aggrecan and link protein and by beta-xyloside treatment. Nevertheless, hyaluronan seems to predominate over the other molecules in mediating chondrocyte-matrix interactions.     

Late effects of ionizing radiation on the microvascular networks in normal tissue

Damage to the microvascular networks constitutes one of the most important components of ionizing radiation damage to normal tissue. Previously, we have reported the early (3, 7 and 30 days postirradiation) effects of ionizing radiation on the structure and function of normal tissue microvascular networks. Here we report on the late effects of ionizing radiation on the structural and functional changes in microvascular networks in locally irradiated (single 10-Gy dose) hamster cremaster muscles observed 60, 120 and 180 days postirradiation; age-matched animals were used as controls. As in the previous study, intravital microscopy was used to measure structural and functional parameters in complete microvascular networks in vivo. A factorial design was used to examine the effects of radiation status, time postirradiation, and network vessel type on the structure and function of microvascular networks. Our results indicate that the progression of radiation-induced microvascular damage continues during the late times but that there is partial recovery from radiation damage within 6 months postirradiation. Red blood cell flux, red blood cell velocity, and capillary blood flow in irradiated networks at 180 days postirradiation were significantly greater than control levels. As at the early times, all vessel types were not damaged equally by radiation at every time.