The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform

William S Dynan - One of the best experts on this subject based on the ideXlab platform.

  • use of a microscope stage mounted nickel 63 microirradiator for real time observation of the dna double strand break response
    Nucleic Acids Research, 2010
    Co-Authors: Wendy Kuhne, Jennifer L Steeb, Mark A Merkley, Yunfeng Zhou, Jiri Janata, William S Dynan
    Abstract:

    : Eukaryotic cells begin to assemble discrete, nucleoplasmic repair foci within seconds after the onset of exposure to ionizing radiation. Real-time imaging of this assembly has the potential to further our understanding of the effects of medical and environmental radiation exposure. Here, we describe a microirradiation system for targeted delivery of ionizing radiation to individual cells without the need for specialized facilities. The system consists of a 25-micron diameter electroplated Nickel-63 electrode, enveloped in a glass capillary and mounted in a micromanipulator. Because of the low energy of the beta radiation and the minute total amount of isotope present on the tip, the device can be safely handled with minimum precautions. We demonstrate the use of this system for tracking assembly of individual repair foci in real time in live U2OS human osteosarcoma cells. Results indicate that there is a subset of foci that appear and disappear rapidly, before a Plateau Level is reached approximately 30 min post-exposure. This subset of foci would not have been evident without real-time observation. The development of a microirradiation system that is compatible with a standard biomedical laboratory expands the potential for real-time investigation of the biological effects of ionizing radiation.

W. Mark Saltzman - One of the best experts on this subject based on the ideXlab platform.

  • Aggregation enhances catecholamine secretion in cultured cells.
    Tissue Engineering, 2001
    Co-Authors: Samuel P. Baldwin, W. Mark Saltzman
    Abstract:

    Transplanted cells and tissues have potential uses in the treatment of genetic, geriatric, and metabolic disorders, but optimal conditions for transplantation are not yet known. In this report, PC12 cells were aggregated in rotary and microgravity culture, using serum-free or serum-supplemented medium, and using a multifunctional polymer-peptide aggregation factor. Aggregates and single cells were then encapsulated and cultured within agarose gels, and the dopamine secretion in response to a depolarization buffer was measured using high-performance liquid chromatography combined with electrochemical detection (HPLC-ECD). On a per-cell basis, aggregated cells secreted higher Levels of dopamine than did single cells. The size of the aggregates was also a factor in catecholamine secretion; dopamine release from the larger aggregates formed in rotary culture was observed to increase at a faster rate, then achieve a Plateau Level at an earlier time than did the smaller aggregates. Cells aggregated in micrograv...

Yie W. Chien - One of the best experts on this subject based on the ideXlab platform.

  • Mutual hairless rat skin permeation‐enhancing effect of ethanol/water system and oleic acid
    Journal of Pharmaceutical Sciences, 1996
    Co-Authors: Yie W. Chien
    Abstract:

    The mutual hairless rat skin permeation-enhancing effect of ethanol (EtOH)/water systems and oleic acid (OA) was investigated with model lipophilic (estradiol, progesterone, levonorgestrel) and hydrophilic drugs (zalcitabine, didanosine, zidovudine). The aqueous solubility and hairless rat skin permeation rate of each drug, saturated in various compositions of EtOH/water system (with and without OA), was determined at 37°C. The hairless rat skin permeation rates of ethanol from EtOH/water systems (with and without OA) were also measured to investigate the skin permeation-enhancing mechanism of EtOH/water systems and OA. Both saturated solubility and steady-state permeation rates of each drug in EtOH/water systems increased exponentially as the volume fraction of ethanol increased, reached the maximum value, and then decreased with further increases in the ethanol volume fraction. Moreover, the hairless rat skin permeation rate of each drug had a good linear relationship with that of ethanol up to 70% (v/v) of ethanol in the EtOH/water system. The addition of OA in the EtOH/water system (70:30 and 60:40 for lipophilic and hydrophilic drugs, respectively) further enhanced the skin permeation rate of both ethanol and drugs. However, > 2.0% (v/v) OA was required to achieve the Plateau Level in the skin permeation rate of lipophilic drugs, whereas only 0.3% (v/v) OA was required for hydrophilic drugs. The skin permeation rate of ethanol also increased with the addition of OA in the EtOH/water systems (70:30 and 60:40), reached the Plateau Level with < 1.0% (v/v) OA, and did not significantly change with higher OA concentration. These results suggest that the addition of OA in the EtOH/water system is a useful method to enhance the hairless rat skin permeation rate of both hydrophilic and lipophilic drugs, with more enhancement for hydrophilic drugs.

Wendy Kuhne - One of the best experts on this subject based on the ideXlab platform.

  • use of a microscope stage mounted nickel 63 microirradiator for real time observation of the dna double strand break response
    Nucleic Acids Research, 2010
    Co-Authors: Wendy Kuhne, Jennifer L Steeb, Mark A Merkley, Yunfeng Zhou, Jiri Janata, William S Dynan
    Abstract:

    : Eukaryotic cells begin to assemble discrete, nucleoplasmic repair foci within seconds after the onset of exposure to ionizing radiation. Real-time imaging of this assembly has the potential to further our understanding of the effects of medical and environmental radiation exposure. Here, we describe a microirradiation system for targeted delivery of ionizing radiation to individual cells without the need for specialized facilities. The system consists of a 25-micron diameter electroplated Nickel-63 electrode, enveloped in a glass capillary and mounted in a micromanipulator. Because of the low energy of the beta radiation and the minute total amount of isotope present on the tip, the device can be safely handled with minimum precautions. We demonstrate the use of this system for tracking assembly of individual repair foci in real time in live U2OS human osteosarcoma cells. Results indicate that there is a subset of foci that appear and disappear rapidly, before a Plateau Level is reached approximately 30 min post-exposure. This subset of foci would not have been evident without real-time observation. The development of a microirradiation system that is compatible with a standard biomedical laboratory expands the potential for real-time investigation of the biological effects of ionizing radiation.

Jussi V. K. Kukkonen - One of the best experts on this subject based on the ideXlab platform.

  • Metabolic response of Lumbriculus variegatus to respiratory uncoupler in cold and anoxic water
    Environmental Toxicology and Chemistry, 2000
    Co-Authors: Olli-pekka Penttinen, Jussi V. K. Kukkonen
    Abstract:

    A direct calorimetry approach was applied to compare physiological interaction of pentachlorophenol (PCP) with the energy metabolism under anoxia and normoxia in the aquatic oligochaete worm Lumbriculus variegatus. In normoxia, heat dissipation begins to accelerate 10 h after the onset of PCP exposure until it settles at a new Plateau Level, and shows a twofold increase from the nonimpact rate. In anoxia, heat output was suppressed down to a Level of ∼18% (7°C) of normoxia. An anoxic PCP exposure did not produce any notable changes in the heat output, and the amount of chemical accumulated in tissues was only a fraction (18%) of that accumulated in normoxia. Whether the inhibition of the physiological response during anoxia was due to a shift to anaerobic metabolism or to reduced accumulation in tissues, or combination of both factors, was unclear.