Search results for " LAB"

Isolation and characterization of Oct-4+/HLA-G+ mesenchymal stem cells from human umbilical cord matrix: differentiation potential and detection of n…

2008

The presence of multipotent cells in several adult and embryo-related tissues opened new paths for their use in regenerative medicine. Extraembryonic tissues such as umbilical cord are considered a promising source of stem cells, potentially useful in therapy. The characterization of cells from the umbilical cord matrix (Wharton''s Jelly) and amniotic membrane revealed the presence of a population of mesenchymal-like cells, sharing a set of core-markers expressed by "mesenchymal stem cells". Several reports enlightened the differentiation capabilities of these cells, even if at times the lack of an extensive characterization of surface markers and immune co-stimulators expression revealed h…

Exclusively juvenile centrioles inXenopus laevis oocytes injected with preparations of mature centrioles

1999

Activated oocytes of Xenopus laevis were injected with centriole preparations isolated either from spermatozoa of loach fish Misgurnus fossilis or from rat liver. These injections induced the development of cytasters in the ooplasm and egg cleavage. Electron microscopic study of cytasters was made at the stage that corresponded to interphase between first and second cleavage divisions. This study revealed in cytasters singleton centrioles surrounded by pericentriolar material and numerous microtubules. Surprisingly, the ultrastructure of centrioles in cytasters corresponded to that of juvenile, newly formed vertebrate centrioles, whereas the injected preparations contained only adult mature…

Supravital Uptake of Methylene Blue by Dendritic Cells within Stratified Squamous Epithelia: a Light and Electron Microscope Study

1996

Electron microscopic data on methylene blue staining of dendritic cells in the epithelia of the soft palate and skin of the mouse after supravital dye injection are presented. The ultra-structural details were compared with corresponding light microscopic findings. Methylene blue stained tissue was fixed by immersion in a paraformaldehyde-glutaraldehyde solution containing phosphomolybdic acid. The ensuing dye precipitate was stabilized by ammonium heptamolybdate. The light microscopic investigation revealed that selective staining of dendritic cells depended on the presence of ambient oxygen. In addition, delicate morphological characteristics, like spinous structures of the dendrites, wer…

Differential staining of mucin granules from epoxy resin sections by a phosphotungstic acid-methyl green procedure.

1991

After treatment of epoxy resin semithin sections from glutaraldehyde fixed rat large intestine with 5% aqueous phosphotungstic acid (PTA), staining with unpurified 0.2% solutions of methyl green at 60 C for 5 min produces a color differentiation between mucin granules of goblet cells. Some mucin granules and the glycocalyx appear deep green while the remaining granules, luminal mucin and collagen fibers are pink. The known contamination of unpurified methyl green with crystal violet seems to be responsible for the pink staining reaction of the latter structures, which also present an orange-red fluorescence under green exciting light. Electron microscopic observations show selective contras…

Nitric oxide: Relation to integrity, injury, and healing of the gastric mucosa

2001

Nitric oxide (NO) plays a multifaceted role in mucosal integrity. The numerous functions of NO and the double-edged role played by NO in most of them provide a great complexity to the NO action. The three enzymatic sources of NO, neuronal NO-synthase (nNOS), endothelial NOS (eNOS), and inducible NOS (iNOS), have been characterised in the gastrointestinal tract. The protective properties of the NO derived from constitutive NO-synthases (eNOS and nNOS) have already been well established. Less clear is the role assigned to iNOS. The simplistic initial view of low levels of NO synthesised by constitutive NOS being protective while exaggerated NO levels after iNOS induction leading irremediably …

My life in Wittekind's lab.

2007

Immunohistochemical detection of EWS and FLI-1 proteinss in Ewing sarcoma and primitive neuroectodermal tumors: comparative analysis with CD99 (MIC-2…

2001

The molecular analysis of the t(11;22) rearrangement involving EWS/FLI-1 genes is likely to be of diagnostic value in Ewing sarcoma (ES) and primitive neuroectodermal tumors (PNET). The objective of the current study was to analyze the immunohistochemical expression of the EWS and FLI-1 proteins in a group of small round-cell tumors (SRCT) to determine their specificity and relevance in their differential diagnosis. Forty-eight cases-10 conventional ES, 4 large-cell ES, 5 PNET, 9 neuroblastomas (NB), 6 undifferentiated synovial sarcomas (SS), 5 rhabdomyosarcomas (RB), 5 non-Hodgkin lymphomas (NHL), 1 round-cell liposarcoma, and 3 mesenchymal chondrosarcomas-were analyzed. Immunocytochemistr…

2019

Atomic force microscopy (AFM) is today an established tool in imaging and determination of mechanical properties of biomaterials. Due to their complex organization, those materials show intricate properties such as viscoelasticity. Therefore, one has to consider that the loading rate at which the sample is probed will lead to different mechanical response (properties). In this work, we studied the dependence of the mechanical properties of endothelial cells on the loading rate using AFM in force spectroscopy mode. We employed a sharp, four-sided pyramidal indenter and loading rates ranging from 0.5 to 20 μm/s. In addition, by variation of the load (applied forces from 100 to 10,000 pN), the…

Optical-sectioning improvement in two-color excitation scanning microscopy

2004

We present a new beam-shaping technique for two-color excitation fluorescence microscopy. We show that by simply inserting a properly designed shaded-ring filter in the illumination beam of smaller wavelength, it is possible to improve the effective optical sectioning capacity of such microscopes by 23%. Such an improvement is obtained at the expense of only a very small increasing of the overall energy in the point-spread-function sidelobes. The performance of this technique is illustrated by a numerical imaging simulation.

Measuring (biological) materials mechanics with atomic force microscopy. 2. Influence of the loading rate and applied force (colloidal particles)

2020

Atomic force microscopy (AFM) is the most often used tool to study the mechanical properties of eukaryotic cells. Due to their complex assembly, cells show viscoelastic properties. When performing experiments, one has to consider the influence of both loading rate and maximum load on the measured mechanical properties. Here, we employed colloidal particles of various sizes (from 2 to 20 μm diameter) to perform force spectroscopy measurements on endothelial cells at loading rates varying from 0.1 to 50 μm/s, and maximum loads ranging from 1 to 25 nN. We were able to determine the non-linear dependence of cell viscoelastic properties on the loading rate which followed a weak power law. In add…