1
|
McNeill JM, Choi YC, Cai YY, Guo J, Nadal F, Kagan CR, Mallouk TE. Three-Dimensionally Complex Phase Behavior and Collective Phenomena in Mixtures of Acoustically Powered Chiral Microspinners. ACS Nano 2023; 17:7911-7919. [PMID: 37022928 DOI: 10.1021/acsnano.3c01966] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The process of dynamic self-organization of small building blocks is fundamental to the emergent function of living systems and is characteristic of their out-of-equilibrium homeostasis. The ability to control the interactions of synthetic particles in large groups could lead to the realization of analogous macroscopic robotic systems with microscopic complexity. Rotationally induced self-organization has been observed in biological systems and modeled theoretically, but studies of fast, autonomously moving synthetic rotors remain rare. Here, we report switchable, out-of-equilibrium hydrodynamic assembly and phase separation in suspensions of acoustically powered chiral microspinners. Semiquantitative modeling suggests that three-dimensionally (3D) complex spinners interact through viscous and weakly inertial (streaming) flows. The interactions between spinners were studied over a range of densities to construct a phase diagram, which included gaseous dimer pairing at low density, collective rotation and multiphase separation at intermediate densities, and ultimately jamming at high density. The 3D chirality of the spinners leads to self-organization in parallel planes, forming a three-dimensionally hierarchical system that goes beyond the 2D systems that have so far been modeled computationally. Dense mixtures of spinners and passive tracer particles also show active-passive phase separation. These observations are consistent with recent theoretical predictions of the hydrodynamic coupling between rotlets generated by autonomous spinners and provide an exciting experimental window to the study of colloidal active matter and microrobotic systems.
Collapse
Affiliation(s)
- Jeffrey M McNeill
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Yun Chang Choi
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Yi-Yu Cai
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jiacen Guo
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - François Nadal
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, United Kingdom
| | - Cherie R Kagan
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Thomas E Mallouk
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| |
Collapse
|
2
|
Gao T, McNeill JM, Oliver VA, Xiao L, Mallouk TE. Geometric and Scaling Effects in the Speed of Catalytic Enzyme Micropumps. ACS Appl Mater Interfaces 2022; 14:39515-39523. [PMID: 35984896 DOI: 10.1021/acsami.2c09555] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Self-powered, biocompatible pumps in the nanometer to micron length scale have the potential to enable technology in several fields, including chemical analysis and medical diagnostics. Chemically powered, catalytic micropumps have been developed but are not able to function well in biocompatible environments due to their intolerance of salt solutions and the use of toxic fuels. In contrast, enzymatically powered catalytic pumps offer good biocompatibility, selectivity, and scalability, but their performance at length scales below a few millimeters, which is important to many of their possible applications, has not been well tested. Here, urease-based enzyme pumps of millimeter and micrometer dimensions were fabricated and studied. The scaling of the pumping velocity was measured experimentally and simulated by numerical modeling. Pumping speeds were analyzed accurately by eliminating Brownian noise from the data using enzyme patches between 5 mm and 350 μm in size. Pumping speeds of microns per second could be achieved with urease pumps and were fastest when the channel height exceeded the width of the catalytic pump patch. In all cases, pumping was weak when the dimensions of the patch were 100 μm or less. Experimental and simulation results were consistent with a density-driven pumping mechanism at all sizes studied and served as a framework for the in silico study of more complex two-dimensional (2D) and three-dimensional (3D) geometries. Attempts to create directional flow by juxtaposing inward and outward pumps were unsuccessful because of the symmetry of convection rolls produced by millimeter-size pump patches and the slow speeds of smaller pumps. However, simulations of a corrugated ratchet structure showed that directional pumping could be achieved with pump patches in the millimeter size range.
Collapse
Affiliation(s)
- Tianyue Gao
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jeffrey M McNeill
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Vincent A Oliver
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Langqiu Xiao
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Thomas E Mallouk
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| |
Collapse
|
3
|
Kan M, Yan ZW, Wang X, Hitt JL, Xiao L, McNeill JM, Wang Y, Zhao Y, Mallouk TE. Berichtigung: 2‐Aminobenzenethiol‐Functionalized Silver‐Decorated Nanoporous Silicon Photoelectrodes for Selective CO
2
Reduction. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
4
|
Kan M, Yan ZW, Wang X, Hitt JL, Xiao L, McNeill JM, Wang Y, Zhao Y, Mallouk TE. Corrigendum: 2-Aminobenzenethiol-Functionalized Silver-Decorated Nanoporous Silicon Photoelectrodes for Selective CO 2 Reduction. Angew Chem Int Ed Engl 2021; 60:6854. [PMID: 33725424 DOI: 10.1002/anie.202101640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
5
|
Kan M, Yan ZW, Wang X, Hitt JL, Xiao L, McNeill JM, Wang Y, Zhao Y, Mallouk TE. 2-Aminobenzenethiol-Functionalized Silver-Decorated Nanoporous Silicon Photoelectrodes for Selective CO 2 Reduction. Angew Chem Int Ed Engl 2020; 59:11462-11469. [PMID: 32249497 DOI: 10.1002/anie.202001953] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Indexed: 01/17/2023]
Abstract
A molecularly thin layer of 2-aminobenzenethiol (2-ABT) was adsorbed onto nanoporous p-type silicon (b-Si) photocathodes decorated with Ag nanoparticles (Ag NPs). The addition of 2-ABT alters the balance of the CO2 reduction and hydrogen evolution reactions, resulting in more selective and efficient reduction of CO2 to CO. The 2-ABT adsorbate layer was characterized by Fourier transform infrared (FTIR) spectroscopy and modeled by density functional theory calculations. Ex situ X-ray photoelectron spectroscopy (XPS) of the 2-ABT modified electrodes suggests that surface Ag atoms are in the +1 oxidation state and coordinated to 2-ABT via Ag-S bonds. Under visible light illumination, the onset potential for CO2 reduction was -50 mV vs. RHE, an anodic shift of about 150 mV relative to a sample without 2-ABT. The adsorption of 2-ABT lowers the overpotentials for both CO2 reduction and hydrogen evolution. A comparison of electrodes functionalized with different aromatic thiols and amines suggests that the primary role of the thiol group in 2-ABT is to anchor the NH2 group near the Ag surface, where it serves to bind CO2 and also to assist in proton transfer.
Collapse
Affiliation(s)
- Miao Kan
- School of Environmental Science and Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, China.,Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Zhifei Wang Yan
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Xingtao Wang
- School of Environmental Science and Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jeremy L Hitt
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Langqiu Xiao
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Jeffrey M McNeill
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yong Wang
- School of Environmental Science and Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yixin Zhao
- School of Environmental Science and Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Thomas E Mallouk
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| |
Collapse
|
6
|
Kan M, Yan ZW, Wang X, Hitt JL, Xiao L, McNeill JM, Wang Y, Zhao Y, Mallouk TE. 2‐Aminobenzenethiol‐Functionalized Silver‐Decorated Nanoporous Silicon Photoelectrodes for Selective CO
2
Reduction. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202001953] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Miao Kan
- School of Environmental Science and Engineering Frontiers Science Center for Transformative Molecules Shanghai Jiao Tong University Shanghai 200240 China
- Department of Chemistry University of Pennsylvania Philadelphia PA 19104 USA
| | - Zhifei Wang Yan
- Department of Chemistry University of Pennsylvania Philadelphia PA 19104 USA
| | - Xingtao Wang
- School of Environmental Science and Engineering Frontiers Science Center for Transformative Molecules Shanghai Jiao Tong University Shanghai 200240 China
| | - Jeremy L. Hitt
- Department of Chemistry University of Pennsylvania Philadelphia PA 19104 USA
| | - Langqiu Xiao
- Department of Chemistry University of Pennsylvania Philadelphia PA 19104 USA
| | - Jeffrey M. McNeill
- Department of Chemistry University of Pennsylvania Philadelphia PA 19104 USA
| | - Yong Wang
- School of Environmental Science and Engineering Frontiers Science Center for Transformative Molecules Shanghai Jiao Tong University Shanghai 200240 China
| | - Yixin Zhao
- School of Environmental Science and Engineering Frontiers Science Center for Transformative Molecules Shanghai Jiao Tong University Shanghai 200240 China
| | - Thomas E. Mallouk
- Department of Chemistry University of Pennsylvania Philadelphia PA 19104 USA
| |
Collapse
|
7
|
McNeill JM, Nama N, Braxton JM, Mallouk TE. Wafer-Scale Fabrication of Micro- to Nanoscale Bubble Swimmers and Their Fast Autonomous Propulsion by Ultrasound. ACS Nano 2020; 14:7520-7528. [PMID: 32432850 DOI: 10.1021/acsnano.0c03311] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Fuel-free, biocompatible swimmers with dimensions smaller than one micrometer have the potential to revolutionize the way we study and manipulate microscopic systems. Sub-micrometer, metallic Janus particles can be propelled rapidly and autonomously by acoustically induced fluid streaming, but their operation at acoustic pressure nodes limits their utility. In contrast, bubble-based microswimmers have an "on board" resonant cavity that enables them to operate far from the source of acoustic power. So far, they have been fabricated by direct writing techniques that limit both their minimum dimensions and the number that can be produced. Consequently, the size scaling of the properties of bubble swimmers has not been explored experimentally. Additionally, 3D autonomous motion has not yet been demonstrated for this type of swimmer. We describe here a method for fabricating bubble swimmers in large numbers (>109) with sizes ranging from 5 μm to 500 nm without direct writing or photolithographic tools. These swimmers follow a previously proposed scaling theory and reveal useful phenomena that enable their propulsion in different modes in the same experiment: with magnetic steering, autonomously in 3D, and in frequency-specific autonomous modes. These interesting behaviors are relevant to possible applications of autonomously moving micro- and nanorobots.
Collapse
Affiliation(s)
- Jeffrey M McNeill
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Nitesh Nama
- Department of Surgery, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jesse M Braxton
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Thomas E Mallouk
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| |
Collapse
|
8
|
Abstract
Dilemmaones A-C are naturally occurring tricyclic indole alkaloids possessing a unique hydroxymethylene or methoxymethylene substituent at the C2 position of the indole core and a C6-C7 fused cyclopentanone. Dilemmaone B has been prepared in 5 steps from 5-methylindan-1-one, and dilemmaone A has been prepared in 3 steps from a common precursor, 6-bromo-5-methyl-7-nitroindan-1-one. In both syntheses, key steps include a Kosugi-Migita-Stille cross coupling and a reductive cyclization using hydrogen gas and a transition metal catalyst.
Collapse
Affiliation(s)
- Katharine E Lambson
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA
| | - Christopher A Dacko
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA
| | - Jeffrey M McNeill
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA
| | - Novruz G Akhmedov
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA
| | - Björn C G Söderberg
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA
| |
Collapse
|
9
|
Ren L, Nama N, McNeill JM, Soto F, Yan Z, Liu W, Wang W, Wang J, Mallouk TE. 3D steerable, acoustically powered microswimmers for single-particle manipulation. Sci Adv 2019; 5:eaax3084. [PMID: 31692692 PMCID: PMC6814402 DOI: 10.1126/sciadv.aax3084] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 09/13/2019] [Indexed: 05/22/2023]
Abstract
The ability to precisely maneuver micro/nano objects in fluids in a contactless, biocompatible manner can enable innovative technologies and may have far-reaching impact in fields such as biology, chemical engineering, and nanotechnology. Here, we report a design for acoustically powered bubble-based microswimmers that are capable of autonomous motion in three dimensions and selectively transporting individual synthetic colloids and mammalian cells in a crowded group without labeling, surface modification, or effect on nearby objects. In contrast to previously reported microswimmers, their motion does not require operation at acoustic pressure nodes, enabling propulsion at low power and far from an ultrasonic transducer. In a megahertz acoustic field, the microswimmers are subject to two predominant forces: the secondary Bjerknes force and a locally generated acoustic streaming propulsive force. The combination of these two forces enables the microswimmers to independently swim on three dimensional boundaries or in free space under magnetical steering.
Collapse
Affiliation(s)
- Liqiang Ren
- Department of Chemistry, Biochemistry and Molecular Biology, Physics, and Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, USA
| | - Nitesh Nama
- Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jeffrey M. McNeill
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Fernando Soto
- Department of Nanoengineering, University of California San Diego, La Jolla, CA 92093, USA
| | - Zhifei Yan
- Department of Chemistry, Biochemistry and Molecular Biology, Physics, and Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, USA
| | - Wu Liu
- Department of Chemistry, Biochemistry and Molecular Biology, Physics, and Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, USA
| | - Wei Wang
- School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
- Corresponding author. (W.W.); (J.W.); (T.E.M.)
| | - Joseph Wang
- Department of Nanoengineering, University of California San Diego, La Jolla, CA 92093, USA
- Corresponding author. (W.W.); (J.W.); (T.E.M.)
| | - Thomas E. Mallouk
- Department of Chemistry, Biochemistry and Molecular Biology, Physics, and Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, USA
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Corresponding author. (W.W.); (J.W.); (T.E.M.)
| |
Collapse
|
10
|
|
11
|
Dilkes MG, McNeill JM, Hill AC, Monks PS, McKelvie P, Hollamby RG. The Hayek oscillator: a new method of ventilation in microlaryngeal surgery. Ann Otol Rhinol Laryngol 1993; 102:455-8. [PMID: 8512273 DOI: 10.1177/000348949310200609] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The Hayek oscillator is an externally (body) mounted cuirass ventilator used in the intensive care unit. We have used it to ventilate patients undergoing microlaryngeal surgery. It was found to be a relatively safe method of ventilation in these cases, with the advantage of dispensing with any form of endolaryngeal or endotracheal intubation.
Collapse
Affiliation(s)
- M G Dilkes
- ENT Department, Royal London Hospital, England
| | | | | | | | | | | |
Collapse
|
12
|
Abstract
Infusions of isotopically labeled [3H] androstenedione with measurement of [3H] estrone in normal breast and breast tumor tissue have been carried out in an attempt to determine the contribution that aromatization makes to the estrogen content of breast tissues. After infusion of [3H] androstenedione for 12h there was significant uptake of this steroid by normal breast and breast tumors. [3H] Estrone was detected in all samples of normal breast tissue examined so far but not in all tumors. Aromatase activity when measured in vitro was found to be higher in breast tumors than in fat next to the tumor or normal breast fat. Studies in which we have examined the effect of epidermal growth factor on aromatase activity in cultured breast adipose tissue suggests that the response may be influenced by a subject's menopausal status. Results from these preliminary studies suggest that the aromatization of androgens may make a significant contribution towards the estrogen content of some breast tumors and that growth factors may also be involved in regulating aromatase activity.
Collapse
Affiliation(s)
- V H James
- Department of Chemical Pathology, St. Mary's Hospital Medical School, London, UK
| | | | | | | | | | | |
Collapse
|
13
|
James VH, McNeill JM, Beranek PA, Bonney RC, Reed MJ. The role of tissue steroids in regulating aromatase and oestradiol 17 beta-hydroxysteroid dehydrogenase activities in breast and endometrial cancer. J Steroid Biochem 1986; 25:787-90. [PMID: 3807364 DOI: 10.1016/0022-4731(86)90309-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We have observed that oestradiol concentrations in breast and endometrial tumours are relatively higher than oestrone, in contrast to peripheral tissues. Infusion of radiolabelled oestrogen also suggested there was a difference in metabolism between normal and tumour tissue. We have therefore looked for factors which could modulate tissue steroid metabolism and conclude that progesterone may influence aromatase, and that the adrenal androgens can inhibit oestradiol dehydrogenase activity. The latter mechanism, in particular, may be important in increasing tissue exposure to oestradiol.
Collapse
|
14
|
McNeill JM, Reed MJ, Beranek PA, Bonney RC, Ghilchik MW, Robinson DJ, James VH. A comparison of the in vivo uptake and metabolism of 3H-oestrone and 3H-oestradiol by normal breast and breast tumour tissues in post-menopausal women. Int J Cancer 1986; 38:193-6. [PMID: 3733259 DOI: 10.1002/ijc.2910380208] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
After infusion of 3H-oestradiol or 3H-oestrone into post-menopausal women with breast cancer, there was a significant uptake of both steroids by breast tumour and normal tissue. The proportion of oestrogen present in tumour tissue as 3H-oestradiol after infusion of 3H-oestradiol (89.4 +/- 3.5%, mean +/- SD, n = 4) was significantly higher (p less than 0.001) than in normal breast tissue (72.8 +/- 3.3%) obtained from the same women. Similarly, after infusion of 3H-oestrone, the proportion of oestrogen present as 3H-oestradiol (48.4 +/- 14.4%) was significantly higher than in normal breast tissue (19.1 +/- 6.4%). These results suggest that conversion of oestrone to oestradiol is enhanced in breast tumour tissue with little metabolism of oestradiol. This would account for the higher concentrations of oestradiol reported in breast tumour tissue in the presence of increased oestradiol 17 beta-hydroxysteroid dehydrogenase activity.
Collapse
|
15
|
McNeill JM, Reed MJ, Beranek PA, Newton CJ, Ghilchik MW, James VH. The effect of epidermal growth factor, transforming growth factor and breast tumour homogenates on the activity of oestradiol 17 beta hydroxysteroid dehydrogenase in cultured adipose tissue. Cancer Lett 1986; 31:213-9. [PMID: 3486035 DOI: 10.1016/0304-3835(86)90013-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The effect of epidermal growth factor (EGF), transforming growth factor (TGF alpha) and breast tumour homogenates on oestradiol 17 beta hydroxysteroid dehydrogenase (E2DH) activity has been examined using cultured human breast adipose tissue. EGF (100-1000 ng/ml) inhibited E2DH activity (E1----E2) in a dose dependent manner. TGF alpha (250 and 500 ng/ml) stimulated E2DH activity, with conversion of E1----E2 increasing to a greater degree than E2----E1 activity. Breast tumour homogenates (2-10% w/v) also influenced E2DH activity. It is concluded that growth factors, produced by breast tumours, may modulate E2DH activity in tissues surrounding the tumour and thereby influence tumour growth.
Collapse
|
16
|
McNeill JM, Gower JD, Wills ED. The formation of the ultimate carcinogen of benzo(a)pyrene during non-enzymic lipid peroxidation. Biochem Pharmacol 1985; 34:4066-8. [PMID: 4062977 DOI: 10.1016/0006-2952(85)90389-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
17
|
Abstract
Benzo[a]pyrene (B[a]P) when incubated in the presence of peroxidising polyunsaturated fatty acids such as linoleic acid (C18:2), arachidonic acid (C20:4), eicosapentaenoic acid (C20:5) or docosahexaenoic acid (C22:6) was converted to oxidised products. Between 7% and 9% of the B[a]P was oxidised in one hour when incubated with arachidonic acid and docosahexaenoic acid. 1,6- 3,6- and 6,12-Quinone derivatives of B[a]P were identified by HPLC. The products of B[a]P oxidation were shown to be mutagenic when tested using Sister chromatid exchange (SCE) technique and the occurrence of SCEs in CHV79 cells was increased significantly. Lipid peroxides also induced SCEs in the absence of B[a]P and there was a positive correlation between the frequency of SCEs and the extent of lipid peroxidation. The results indicate that the oxidation of B[a]P mediated by the non-enzymic peroxidation of polyunsaturated fatty acids is likely to play a role in mutagenesis and, possibly, also in carcinogenesis.
Collapse
|
18
|
Cohen AS, McNeill JM, Calkins E, Sharp JT, Schubart A. The "normal" sacroiliac joint. Analysis of 88 sacroiliac roentgenograms. Am J Roentgenol Radium Ther Nucl Med 1967; 100:559-63. [PMID: 6028970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|