Comparison of ultrastructural and nanomechanical signature of platelets from acute myocardial infarction and platelet activation.

Acute myocardial infarction (AMI) initiation and progression follow complex molecular and structural changes in the nanoarchitecture of platelets. However, it remains poorly understood how the transformation from health to AMI alters the ultrastructural and biomechanical properties of platelets within the platelet activation microenvironment. Here, we show using an atomic force microscope (AFM) that platelet samples, including living human platelets from the healthy and AMI patient, activated platelets from collagen-stimulated model, show distinct ultrastructural imaging and stiffness profiles. Correlative morphology obtained on AMI platelets and collagen-activated platelets display distinct pseudopodia structure and nanoclusters on membrane. In contrast to normal platelets, AMI platelets have a stiffer distribution resulting from complicated pathogenesis, with a prominent high-stiffness peak representative of platelet activation using AFM-based force spectroscopy. Similar findings are seen in specific stages of platelet activation in collagen-stimulated model. Further evidence obtained from different force measurement region with activated platelets shows that platelet migration is correlated to the more elasticity of pseudopodia while high stiffness at the center region. Overall, ultrastructural and nanomechanical profiling by AFM provides quantitative indicators in the clinical diagnostics of AMI with mechanobiological significance.

A quantitative study of MC3T3-E1 cell adhesion, morphology and biomechanics on chitosan-collagen blend films at single cell level.

The interaction between cells and biomaterials plays a key role in cell proliferation and differentiation in tissue engineering. However, a quantitative analysis of those interactions has been less well studied. The objective of this study was to quantitative recapitulate the difference of MC3T3-E1 cell adhesion, morphological and biomechanical properties on chitosan-collagen films in terms of chemical composition. Here, the unbinding force between MC3T3-E1 cell and a series of chitosan-collagen films was probed by a real-time and in situ atomic force microscopy-single cell force spectroscopy (AFM-SCFS). Meanwhile, changes in cell morphology and Young's modulus on different chitosan-collagen films were detected by AFM. The cell area and CCK-8 results showed that cell spreading and proliferation increased with increasing collagen content. AFM observations clearly showed cell height decreased and pseudopod fusion with the collagen content increased. Cell adhesive force increased from 0.76±0.17 nN to 1.70±0.19 nN. On the contrary, cells Young's modulus, which reflected biophysical changes of cells decreased from 11.94±3.19 kPa to 1.81±0.52 kPa, respectively. It suggested that stronger cell-substrate interactions benefit cell adhesion, and better cell flexibility improve cell spreading. The findings indicate that cell morphology, adhesive force and Young's modulus are significant affected by various chitosan-collagen substrates. Those methods and quantitative results have guiding significance for investigating the mechanism of chitosan and/or collagen based cell-targeting drug carrier and the preparation of chitosan-collagen composite biomaterials.

In-situ detection of resveratrol inhibition effect on epidermal growth factor receptor of living MCF-7 cells by Atomic Force Microscopy.

A new method based on Atomic Force Microscopy (AFM) was developed to real-time and in-situ detect epidermal growth factor receptor (EGFR) expression levels on living MCF-7 cells for evaluating the anticancer activity of resveratrol. Here, the inhibition effect of resveratrol on EGFR expression levels on MCF-7 cells was probed by epidermal growth factor (EGF)-functionalized tips for the first time. Changes in morphology and stiffness of single cell stimulated by resveratrol at different concentrations were detected by AFM. The consequences showed that resveratrol influenced the cellular state and reduced expression of EGFR on the cell surface, which were also interpreted by MTT assay and confocal microscopy assay. AFM, which was used to investigate potential targets for anti-tumor drug on living cells and realize a better understanding of drug action mechanism, was expected to be developed into a promising tool for screening of drugs.

Eucomic acid methanol monosolvate.

IN THE CRYSTAL STRUCTURE OF THE TITLE COMPOUND [SYSTEMATIC NAME: 2-hy-droxy-2-(4-hy-droxy-benz-yl)butane-dioic acid methanol monosolvate], C(11)H(12)O(6)·CH(3)OH, the dihedral angles between the planes of the carboxyl groups and the benzene ring are 51.23 (9) and 87.97 (9)°. Inter-molecular O-H⋯O hydrogen-bonding inter-actions involving the hy-droxy and carb-oxy-lic acid groups and the methanol solvent mol-ecule give a three-dimensional structure.

Mycotoxin Ochratoxin A-induced cell death and changes in oxidative metabolism of Arabidopsis thaliana.

We evaluated the phytotoxicity of mycotoxin ochratoxin A (OTA) from Aspergillus and Penicillium strains on Arabidopsis thaliana. The results demonstrate that the growth of Arabidopsis thaliana on media containing OTA was inhibited significantly. Moreover, OTA induced necrotic lesions in detached leaves, which are reminiscent of hypersensitive response lesions that are activated during plant-pathogen interactions and other abiotic stress factors. From our study, we can see that OTA exposure stimulated a biphasic oxidative burst in the leaves, resulting in the generation of hydrogen peroxide (H2O2) and superoxide anion radicals (O2(.-)) and in the concomitant down-regulation of antioxidant enzyme defense responses and up-regulation of lipid peroxidation. These results suggested that OTA damage might result from reactive oxygen species pathways. Our experiments provide a useful model plant system for research on OTA-induced plant cell death.

Flavobacterium tiangeerense sp. nov., a cold-living bacterium isolated from a glacier.

A novel cold-living, Gram-stain-negative, yellow-pigmented and obligately aerobic bacterium designated strain 0563(T) was isolated from the China No. 1 glacier. Phylogenetic analysis showed that strain 0563(T) was a member of the genus Flavobacterium, sharing the highest 16S rRNA gene sequence similarities with Flavobacterium limicola JCM 11473(T) (98.5 %) and Flavobacterium psychrolimnae NBRC 102679(T) (98.2 %). The genomic DNA G+C content was 34.8 mol%. Strain 0563(T) displayed the common phenotypic and chemotaxonomic features of the genus Flavobacterium, containing menaquinone-6 (MK-6) as the major quinone and iso-C(15 : 0), iso-C(15 : 0) 3-OH, summed feature 3 (comprising C(16 : 1)omega7c and/or C(16 : 1)omega6c), C(15 : 1)omega6c, iso-C(15 : 1) G and iso-C(16 : 0) 3-OH as the major fatty acids. On the basis of phenotypic characteristics, phylogenetic analysis and DNA-DNA relatedness data, the novel species Flavobacterium tiangeerense sp. nov. is proposed; the type strain is 0563(T) (=CGMCC 1.6847(T) =JCM 15087(T)).

Isolation and characterization of ZH14 with antiviral activity against Tobacco mosaic virus.

A large number of bacteria were isolated from plant samples and screened for antiviral activity against the Tobacco mosaic virus (TMV). The bacterium ZH14, which was isolated from Chinese Anxi oolong tea, secreted the antiviral substances, having 94.2% virus inhibition when the bacterial culture filtrate and TMV extract were mixed at a ratio of 1:1. The ZH14 strain is a gram-positive, spore-forming rod and has the ability to degrade ribonucleic acid. Based on its effectiveness on virus inhibition, ZH14 was selected for characterization and was identified as a strain of the Bacillus cereus group based on phenotypic tests and comparative analysis of its 16S rDNA sequence. At the same time, we determined the antiviral product of ZH14 as an extracellular protein with high molecular mass, having an optimum temperature of 15-60 degrees C and an optimum pH of 6-10. Hence, the ZH14 strain and its culture filtrate have potential application in controlling plant diseases caused by TMV.

[The ultrastructure study of membrane surface of the bone marrow CD34+ cells with the atomic force microscope].

Human CD34(+) hematopoietic cells, a distinctive cell population containing hematopoietic stem/progenitor cells (HSPC), have the capability to highly self-renewal, differentiation into all lineages of committed progenitor cells and reconstitution of both long-term hematopoiesis and immunefunctions after transplantation. CD34(+) hematopoietic cells from bone marrow (BM) recently have been employed for treating neoplastic and genetic disorders. This study was aimed to investigate membrane surface ultrastructures of bone marrow CD34(+) cell from mormal persons and leukemia patients and to compare their morphologic differences by using atomic force microscope (AFM). BM was collected from 5 normal donors and 6 leukaemia patients. All samples were layered on Ficoll-Paque gradients (specific gravity 1.077 g/ml) to separate the mononuclear cells. After that CD34(+) cells were purified by immuno-magnetic bead separation and evaluated with a FACS Calibur, these cells were detected by AFM of tapping mode inair. At lest 20 cells per samples were observed. The results showed that most of CD34(+) hematopoietic cells were like circle plate, the diameter was 10 - 14 microm. The surface of CD34(+) hematopoietic cell membrane was comparatively complex. The surface of CD34(+) hematopoietic cell membrane appeared as granular, with packed particles. With the region analysis function of IP2.1 software, the region of 2 microm x 2 microm was selected and four parameters of the surface (maximum peak-to-valley distance, average roughness, root-mean-squared roughness and mean height) were measured. Values of the 4 parameters showed that the characteristic parameters of CD34(+) HSPC from leukaemia were higher than that from normal person. It is concluded that AFM has specific advantages in analyzing cell membrane in the nanometer level and can gain more information. With the help of analysis software, AFM can be a helpful tool for fast leukaemic diagnosis and CD34(+) hematopoietic cells selection.