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250 results on '"Grasso, Robert J."'

201. Glucocorticoid-Resistant Glioma Cells That Contain Cytosolic Receptors1

Author

Holbrook, Nikki J., Cox, William I., Hackney, John F., and Grasso, Robert J.

Abstract

The relationship between cytosolic glucocorticoid receptors and two different physiological responses produced by dexamethasone (DEX) was investigated in steroid-sensitive C6 glioma cells and newly-derived, steroid-resistant C6H cells. Cell density measurements showed that cell proliferation was suppressed in 7.6 μMDEX-treated C6 cultures relative to controls. Scanning electron microscopy revealed that DEX-treated C6 cells and their processes were flattened compared to control C6 cells. In contrast, DEX failed to produce a growth-inhibitory response and morphological alterations in C6H cultures. Whole cell assays for glucocorticoid receptors indicated that specific binding (cpm/mg protein) of [3H]DEX and [3H]triamcinolone acetonide was similar in C6 and C6H cells. Assays employing cell-free preparations also showed that C6 and C6H cells contained similar amounts of steroid binding to cytosolic receptor sites. Thus, the loss of two physiological responses to DEX action in C6H cells is due to some metabolic defect other than the loss of cytosolic glucocorticoid receptors.

Published
1980
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202. Increased Volumes of Mitochondria and Granular Endoplasmic Reticulum in Rat Glioma Cells Treated with Anti-tumor Agents1

Author

Grasso, Robert J., Moore, N. Anthony, Boler, R. Keith, and Johnson, Charles E.

Abstract

The effects of DEX (1 and 10 μM) and BCNU (1 and 10 μM), alone and in combination, on the ultrastructure of rat glioma (strain C6) cells were investigated during the growth-inhibitory responses produced by these antitumor agents. Volume fractions of cellular structures were determined by morphometric analysis employing stereologic techniques. Relative to controls (100%), mitochondrial volumes increased 129-166% in C6 cells exposed to DEX for 1 day. Volumes of granular endoplasmic reticulum increased 189-245% in cells exposed to DEX for 2 days or BCNU for 1 day. When C6 cells pretreated with DEX for 1 day were exposed to BCNU for an additional day, granular endoplasmic reticulum volumes increased 267-300%.These results suggest that the antitumor agents may interfere with common components of those mechanisms that regulate mitosis and the ultrastructure of mitochondria and granular endoplasmic reticulum in C6 cells.

Published
1977
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203. Loss of Host-controlled Restriction of ? Bacteriophage in Escherichia coliFollowing Methionine Deprivation 1

Author

Grasso, Robert J. and Paigen, Kenneth

Abstract

? Bacteriophages produced in Escherichia coliC (designated as ? · C) are restricted in their ability to grow in E. coliK-12. The rare successful infections that arise in the K-12 population occur in “special” cells which have lost their capacity to restrict ? · C. These infections yield modified progeny phage (designated as ? · K) which, unlike ? · C, plate equally well on E. coliC and E. coliK-12. When methionine, but no other amino acid, was removed from the growth medium of a mutant strain of E. coliK-12, the number of special cells rapidly increased 500- to 3,000-fold. These new special cells retain their capacity to produce modified ? · K progeny. This conversion of restricting cells into special cells does not require the synthesis of new protein. The special cells formed when methionine was removed from the culture did not revert into restricting cells when methionine was restored. Such cells have also lost the ability to divide for at least 4 hr after methionine supplementation. When methionine was restored, the remaining restricting cells, but not the special cells, immediately resumed growth. Removing methionine from cultures of E. coliB caused a similar increase in the number of special cells able to support the growth of ? · C and ? · K. However, when E. coliK-12 (P1) cultures were deprived of methionine, the number of special cells increased for ? · C but not for ? · K. Thus, retention of the P1-restriction system, unlike the B- and the K-12-systems, does not require the presence of methionine.

Published
1968
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218. Increased Sensitivity of a New Coagglutination Test for Rapid Identification of Haemophilus influenzaeType b

Author

Grasso, Robert J., West, Loyd A., Holbrook, Nikki J., Halkias, Demetrios G., Paradise, Lois J., and Friedman, Herman

Abstract

A newly developed rapid coagglutination test for identifying Haemophilus influenzaetype b organisms isolated from clinical specimens correlated 100% with the slide agglutination test but was 100- to 200-fold more sensitive.

Published
1981
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244. Progress in efficiency-optimized high-power diode lasers

Author

Titterton, David H., Richardson, Mark A., Grasso, Robert J., Ackermann, Harro, Bohn, Willy L., Pietrzak, A., Hülsewede, R., Zorn, M., Hirsekorn, O., Sebastian, J., Meusel, J., Hennig, P., Crump, P., Wenzel, H., Knigge, S., Maaßdorf, A., Bugge, F., and Erbert, G.

Published
2013
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248. Quantum cascade lasers for defense and security

Author

Titterton, David H., Richardson, Mark A., Grasso, Robert J., Ackermann, Harro, Bohn, Willy L., Day, Timothy, Pushkarsky, Michael, Caffey, Dave, Cecchetti, Kristen, Arp, Ron, Whitmore, Alex, Henson, Michael, and Takeuchi, Eric B.

Published
2013
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249. Laser detection utilizing coherence

Author

David M. Benton, Kate Sugden, Marie Zandi, Titterton, David H., Grasso, Robert J., and Richardson, Mark A.

Subjects
Interferometry, Optics, Computer science, law, business.industry, Continuous wave, Laser, business, Laser detection, Coherence (physics), law.invention, Range finding
Abstract

Lasers are an unnatural occurrence, rendered almost impossible in nature due to the laws of thermodynamics. Thus, the presence of laser radiation is always accompanied by an intent for that laser such as sensing, targeting, range finding etc. Detection of laser radiation is therefore important as it may be a precursor to impending action. Laser warning receivers have been around for decades and have been aligned with the type of laser threat. In the last few years new threats have appeared in the form of low-cost diode lasers with dangerously high power levels (several Watts for a few hundred US dollars) and an ever expanding range of wavelengths. Protecting against such threats requires its detection, analysis and classification. In this paper we will discuss the types of technologies that have been used to detect lasers and the properties they can discern. We then focus on the developments in the detection of coherence properties and its ability to detect weak continuous wave (CW) laser sources.

Published
2019

250. Brillouin scattering effect in the multicore optical fiber applied to fiber optic shape sensing

Author

Anna Pytel, Michalina Jozwik, Michal Murawski, Luc Thévenaz, Agnieszka Kolakowska, Zhisheng Yang, Barbara Wajnchold, Tomasz Nasilowski, Lukasz Szostkiewicz, Pawel Mergo, Marek Napierala, Titterton, David H., Grasso, Robert J., and Richardson, Mark A.

Subjects
Optical fiber, Materials science, business.industry, Multicore optical fiber technology, Polarization-maintaining optical fiber, Brillouin scattering in multicore optical fibers, Microstructured optical fiber, Graded-index fiber, law.invention, Shape senor, Distributed sensing, Optics, Fiber optic sensor, law, Brillouin scattering, business, Plastic optical fiber, Photonic-crystal fiber
Abstract

A shape sensor exploiting Brillouin scattering measurements in multicore fibers is presented. Based on previous reports1, the shape sensor’s principle of operation is firstly described. The presented idea is realized through Brillouin Frequency Shift (BFS) measurements in the time domain along the entire multicore fiber. The BFS value is related to the strain value in each core and the differential inter-core strains lead to the bend radius and orientation. Authors present an experimental demonstration of the shape sensor using a 7-core microstructured optical fiber.

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