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Scheer E, Belzig W, Naveh Y, Devoret MH, Esteve D, Urbina C. Proximity effect and multiple Andreev reflections in gold atomic contacts. PHYSICAL REVIEW LETTERS 2001; 86:284-287. [PMID: 11177812 DOI: 10.1103/physrevlett.86.284] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2000] [Indexed: 05/23/2023]
Abstract
We investigate the electronic transport properties of gold point contacts with superconducting aluminum leads. The modifications induced by the proximity effect in the quasiparticle density of states at the contact region are measured by tunnel spectroscopy. The theory of transport through multiple Andreev reflections is extended to incorporate these effects and used to determine the number and transmission coefficients of the conduction channels in the contact regime. We find that the smallest contacts, formed by one gold atom between the electrodes, contribute one single channel to the transport with variable transmission T between 0.1 and 1.
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Pardey A, Fernández M, Alvarez J, Urbina C, Moronta D, Leon V, Longo C, Baricelli P, Moya S. The reduction of nitrobenzene as catalyzed by poly(4-vinylpyridine)-immobilized [Rh(COD)(amine)2](PF6) complexes under WGSR conditions. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1381-1169(00)00264-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Goffman MF, Cron R, Joyez P, Devoret MH, Esteve D, Urbina C. Supercurrent in atomic point contacts and andreev states. PHYSICAL REVIEW LETTERS 2000; 85:170-173. [PMID: 10991186 DOI: 10.1103/physrevlett.85.170] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/1999] [Indexed: 05/23/2023]
Abstract
We have measured the supercurrent in aluminum atomic point contacts containing a small number of well characterized conduction channels. For most contacts, the measured supercurrent is adequately described by the opposite contributions of two thermally populated Andreev bound states per conduction channel. However, for contacts containing an almost perfectly transmitted channel 0.9</=tau</=1 the measured supercurrent is higher than expected, a fact that we attribute to nonadiabatic transitions between bound states.
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Mennin SP, Kaufman A, Urbina C, McGrew M. Community-based medical education: toward the health of the public. MEDICAL EDUCATION 2000; 34:503-504. [PMID: 10886627 DOI: 10.1046/j.1365-2923.2000.00738.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Urbina C, Voss C, Seeger K, McHarney-Brown C, Martinez M, Voelz J, Kaufman A. Interdisciplinary ambulatory education and service in primary care at the University of New Mexico. ACADEMIC MEDICINE : JOURNAL OF THE ASSOCIATION OF AMERICAN MEDICAL COLLEGES 1999; 74:659-662. [PMID: 10386092 DOI: 10.1097/00001888-199906000-00010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
To compete and survive in a managed care market, academic health centers must develop integrated delivery systems in general and an integrated primary care system in particular. However, the departmental-based structure at most academic health centers is ill-suited to this purpose. Service and education are usually segregated by department, and the professional activities of primary care faculty in different departments are fragmented, leaving them weakened as a political force within the institution. The University of New Mexico established a model of integrated primary care education and service by creating three interdisciplinary primary care clinics staffed by primary care residents and faculty. The clinics attracted a substantial portion of each department's faculty and residents. The clinics united primary care providers from different departments as a stronger, more unified voice in negotiating with the hospital and in fostering needed changes for primary care in the institution. Interdisciplinary teams require considerable time and labor both in planning (because of joint decision making) and in operation. Better staff structures and staff development must be learned through trial and error because there are not established benchmarks for interdisciplinary teams. Governance presents problems, primarily because loyalties to departments may supersede those to the clinic practice, and sometimes the departments' teaching priorities are challenged by clinic directors' need to ensure filling their interdisciplinary staff needs. These obstacles to collaboration can be addressed creatively, and ultimately the comprehensiveness and quality of care convinces providers and the institution.
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Moreno B, Vidoni O, Ovalles C, Chaudret B, Urbina C, Krentzein H. Synthesis and Characterization of Molybdenum Based Colloidal Particles. J Colloid Interface Sci 1998; 207:251-257. [PMID: 9792767 DOI: 10.1006/jcis.1998.5631] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The synthesis and characterization of molybdenum colloidal particles were evaluated using thermal and sonochemical methods and starting from different metal precursors, Mo(CO)6 and (NH4)2MoS4. The products were characterized by elemental analysis, spectroscopic (UV, FTIR), and surface analysis (XPS) techniques, as well as by transmission electron microscopy (TEM) for determining the particle sizes. Using Mo(CO)6 as metal source, particle sizes with an average diameter of 1.5 nm can be obtained using tert-amyl alcohol as solvent and tetrahydrothiophene as sulfurating ligand. The characterization of these particles showed that they are composed of molybdenum oxide MoO3. Using (NH4)2MoS4 as metal precursor, particles with average diameters of 4.7 and 2.5 nm were synthesized using thermal and sonochemical methods, respectively. The characterization of these particles showed them to be composed of molybdenum sulfide, MoS2. The sonochemical method proved to be the fastest and most convenient synthetic pathway of obtaining small colloidal particles at low temperatures and with control of the average size. Copyright 1998 Academic Press.
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Turlot E, Linkwitz S, Esteve D, Urbina C, Devoret M, Grabert H. High frequency satellites in resonant activation. Chem Phys 1998. [DOI: 10.1016/s0301-0104(98)00127-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kaufman A, Galbraith P, Alfero C, Urbina C, Derksen D, Wiese W, Contreras R, Kalishman N. Fostering the health of communities: a unifying mission for the University of New Mexico Health Sciences Center. ACADEMIC MEDICINE : JOURNAL OF THE ASSOCIATION OF AMERICAN MEDICAL COLLEGES 1996; 71:432-440. [PMID: 9114858 DOI: 10.1097/00001888-199605000-00010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Fostering the health of communities can serve as a unifying mission of the academic health center (AHC), which can set the AHC apart from other health providers in the community. To achieve this mission, the University of New Mexico's AHC is increasingly focusing education, research, and service upon the identified health and service needs of communities in its state. Since major health problems in our society have social, behavioral, and economic roots, New Mexico's AHC has tapped into the broad expertise of its different components as well as that of its state and community partners to adequately address health problems in the community. Its hospitals offer financing and management resources, its colleges offer innovative approaches to community-based education, and the state department of health offers expertise in health policy development. To adequately respond to the complexity of community health needs, the different colleges and departments at New Mexico's AHC are increasingly merging into integrated governance units. Measures of community outreach success include evidence of strengthened community development, increased health care access, and improved indices of community health. New Mexico's AHC formed an interdisciplinary rural outreach task force, which has demonstrated its ability to form partnerships with state and local agencies and to mobilize institutional resources in education, research, and service from the AHC's different departments, colleges, and hospitals to respond promptly to unique community health needs. Evidence shows that such an integrated, coordinated AHC intervention can generate strong and lasting AHC-community alliances, improve the quality and economic viability of community health systems, and enhance the financial resources of the AHC.
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Host T, Esteve D, Urbina C, Devoret MH. Effect of a transmission line resonator on a small capacitance tunnel junction. PHYSICAL REVIEW LETTERS 1994; 73:3455-3458. [PMID: 10057385 DOI: 10.1103/physrevlett.73.3455] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Urbina C, Hickey M, McHarney-Brown C, Duban S, Kaufman A. Innovative generalist programs: academic health care centers respond to the shortage of generalist physicians. J Gen Intern Med 1994; 9:S81-9. [PMID: 8014749 DOI: 10.1007/bf02598122] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Academic health care centers increasingly are exploring innovative ways to increase the supply of generalist physicians. The authors review successful innovations at representative academic health centers in the areas of recruitment and admissions, undergraduate medical education, residency training, and practice support. Lessons learned focus on those areas that have demonstrated improvements in the number and quality of physicians trained in family practice, general pediatrics, and general internal medicine. Successful recruitment of generalism-oriented applicants requires identification and tracking of rural, minority, and other special groups of students at the high school and college levels. Academic health care centers that provide early, sustained, community-based, ambulatory experiences for medical students and residents encourage trainees to maintain and choose generalist careers. Finally, academic health care centers that link with community providers and with state government encourage the retention of generalist physicians through continuing education and teaching networks.
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Wellstood FC, Urbina C, Clarke J. Hot-electron effects in metals. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:5942-5955. [PMID: 10011570 DOI: 10.1103/physrevb.49.5942] [Citation(s) in RCA: 367] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Lafarge P, Joyez P, Esteve D, Urbina C, Devoret MH. Measurement of the even-odd free-energy difference of an isolated superconductor. PHYSICAL REVIEW LETTERS 1993; 70:994-997. [PMID: 10054257 DOI: 10.1103/physrevlett.70.994] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Lefevre-Seguin V, Turlot E, Urbina C, Esteve D, Devoret MH. Thermal activation of a hysteretic dc superconducting quantum interference device from its different zero-voltage states. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:5507-5522. [PMID: 10004337 DOI: 10.1103/physrevb.46.5507] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Lafarge P, Pothier H, Williams ER, Esteve D, Urbina C, Devoret MH. Direct observation of macroscopic charge quantization. ACTA ACUST UNITED AC 1991. [DOI: 10.1007/bf01307627] [Citation(s) in RCA: 225] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Turlot E, Esteve D, Urbina C, Devoret M, Grauer R, Fernandez JC, Politano H, Reinisch G. Dynamical isoperimeter pattern in the square sine-Gordon system. PHYSICAL REVIEW. B, CONDENSED MATTER 1990; 42:8418-8425. [PMID: 9995016 DOI: 10.1103/physrevb.42.8418] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Flores J, Perez-Schael I, Blanco M, White L, Garcia D, Vilar M, Cunto W, Gonzalez R, Urbina C, Boher J. Comparison of reactogenicity and antigenicity of M37 rotavirus vaccine and rhesus-rotavirus-based quadrivalent vaccine. Lancet 1990; 336:330-4. [PMID: 1975333 DOI: 10.1016/0140-6736(90)91876-c] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
90 Venezuelan infants aged 10-20 weeks were randomly allocated to four groups which received one of the following: the M37 vaccine (1 x 10(4) pfu [plaque-forming units]); quadrivalent rotavirus vaccine (1 x 10(4) pfu each of serotype 3 rhesus rotavirus [RRV] and human rotavirus-RRV reassortants of serotypes 1, 2, and 4); balanced quadrivalent vaccine consisting of 1 x 10(4) pfu of serotype 1 and 3 components but 5 x 10(4) pfu of serotype 2 and 4 components; or placebo. The frequencies of transient febrile responses in these four groups were 20%, 27%, 30%, and 9%. 50% of 22 infants tested who received M37 vaccine showed a serum rotavirus IgA antibody response, compared with 74% of the 23 quadrivalent and 86% of the 22 balanced-quadrivalent recipients. 64% of the M37 recipients showed a neutralising antibody response to M37; 27% showed such responses to human serotype 1 Wa strain and 27% to serotype 4 neonatal strain ST3. 17-39% of the quadrivalent recipients and 27-41% of the balanced-quadrivalent recipients showed neutralising antibody responses to serotypes 1-4. 70-73% of the quadrivalent and balanced quadrivalent groups also showed neutralising antibody responses to RRV.
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Geerligs LJ, Anderegg VF, Holweg PA, Mooij JE, Pothier H, Esteve D, Urbina C, Devoret MH. Frequency-locked turnstile device for single electrons. PHYSICAL REVIEW LETTERS 1990; 64:2691-2694. [PMID: 10041785 DOI: 10.1103/physrevlett.64.2691] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Devoret MH, Esteve D, Grabert H, Ingold G, Pothier H, Urbina C. Effect of the electromagnetic environment on the Coulomb blockade in ultrasmall tunnel junctions. PHYSICAL REVIEW LETTERS 1990; 64:1824-1827. [PMID: 10041498 DOI: 10.1103/physrevlett.64.1824] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Morasso MI, Rieber MS, Urbina C, Rieber M. Changes in cytoskeleton-associated molecules in cells with different degrees of proliferation and metastatic ability. CELL BIOLOGY INTERNATIONAL REPORTS 1989; 13:863-72. [PMID: 2805076 DOI: 10.1016/0309-1651(89)90128-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
An antiserum prepared against the Triton-insoluble cytoskeleton of in vivo grown B16 melanoma tumor has been used to analyze the differential expression of cytoskeleton-associated molecules in cells with different degrees of proliferation and metastatic ability. This antiserum identified a major 97 kd molecule associated with the cytoskeletal fraction in B16 melanoma tumors, mouse embryo and in proliferating lymphocytes, with no reactivity with the 97 kd species in non proliferating lymphocytes. The antiserum revealed immune reactivity with a 180 kd Triton-insoluble species in normal adult mouse liver and kidney. A comparison of tumor cells with differing metastatic ability also showed a minor 180 kd component in poorly metastatic cells which appeared decreased and partly degraded in its more invasive counterpart. The differential recognition of a 97 kd species in resting and proliferating lymphocytes, as well as the different cleavage of a 180 kd species in tumor cells of differing metastatic ability, implies a role for these molecules in cell proliferation. The fact that these differences can be detected with an antiserum to tumor cell cytoskeleton suggests that this Triton-insoluble fraction may be a good source of molecules involved in growth control.
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Rieber M, Rieber MS, Urbina C, Lira R. Differential response of adherent and unanchored melanoma cells to bromodeoxyuridine evidenced by specific lectin-binding protein changes. Int J Cancer 1989; 43:841-4. [PMID: 2714888 DOI: 10.1002/ijc.2910430517] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The possible differential response of adherent and nonadherent cells of the same tumor type to pyrimidine analogues has been investigated. We show that bromodeoxyuridine (BUdR) increases interactions of attached cells with their substrate without markedly affecting the cell adhesion properties of the same cells when these are not anchored. However, evidence for an adhesion-independent response of both cell types to BUdR has been obtained with lectin binding assays using 125I-labelled Lens culinaris agglutinin (LCA). This revealed a greatly increased binding of LCA to a large glycoconjugate in all cultures exposed to the halogenated pyrimidine. Attachment-dependent effects of BUdR were manifested in flattened cells by a greater LCA-binding to a 240-kDa protein and by increased interaction of 125I-labelled wheat-germ agglutinin (WGA) with a 200-kDa protein and a large glycoconjugate sharply defined in electrophoresis. Although both tumor cell aggregates and anchored cells exhibit detectable responses to pyrimidine analogues such as BUdR, the corresponding effects are thus manifested unequally in cells with different adhesion properties.
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Turlot E, Esteve D, Urbina C, Martinis JM, Devoret MH, Linkwitz S, Grabert H. Escape oscillations of a Josephson junction switching out of the zero-voltage state. PHYSICAL REVIEW LETTERS 1989; 62:1788-1791. [PMID: 10039768 DOI: 10.1103/physrevlett.62.1788] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Rieber M, Urbina C, Rieber MS. DNA on membrane receptors: a target for monoclonal anti-DNA antibody induced by a nucleoprotein shed in systemic lupus erythematosus. Biochem Biophys Res Commun 1989; 159:1441-7. [PMID: 2784678 DOI: 10.1016/0006-291x(89)92271-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Antibodies to double stranded (ds) DNA correlate with clinical evolution in systemic lupus erythematosus (SLE) although little is known about the immunogen and target for these antibodies, since ds DNA is poorly immunogenic. We now show that monoclonal anti DNA antibodies similar to those detected in human SLE can be produced by immunization of genetically non-autoimmune mice with a human circulating DNA-protein complex increased in the circulation of SLE patients. One such monoclonal antibody showed antinuclear reactivity, interacting with a 74 kd DNA-binding membrane protein, in reactions prevented by absorption with ds DNA cellulose. Our data suggests that anti ds DNA antibody reactions in SLE may be triggered by circulating nucleoproteins and directed toward membrane receptors capable of interacting with extracellular DNA.
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Rieber M, Castillo MA, Rieber MS, Irwin JC, Urbina C. Decrease in tumor-cell attachment and in a 140-kDa fibronectin receptor correlate with greater expression of multiple 34-kDa surface proteins and cytoplasmic 54-kDa components. Int J Cancer 1988; 41:96-100. [PMID: 2961705 DOI: 10.1002/ijc.2910410118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
B16 melanoma cells attach to matrix-bound fibronectin but fail to adhere to albumin-coated surfaces supplemented with soluble fibronectin. Attachment to substratum is also decreased in the presence of an adhesion-disrupting antibody, or when cells are seeded on substrates poorly adhesive for these cells, such as collagen gels. We have now investigated some of the more general adhesion-related alterations that occur between flattened and poorly attached cells. Immune blots of octylglucoside extracts with the adhesion-disrupting IgG revealed a 140-kDa component in flattened cells, in contrast to the increased detection of a 54-kDa species in a comparable assay with rounded cells. Surface iodination also showed a decreased external exposure of a 140-kDa fibronectin binding species and an increased labelling in multiple 34-kDa protein species, in cells with decreased attachment to substratum. Analysis of 35S-methionine-labelled cell aggregates cultured on collagen gels also revealed a decrease in the 140-kDa region and a greater labelling of multiple 54-kDa components, compared to the same cells flattened on fibronectin. A change in 54- and 34-kDa species was also seen in matrix-associated components of rounded cells that failed to attach with soluble fibronectin. Since the 34-kDa species increase in poorly adherent cells is mainly detected by iodination, and the 54-kDa species increase in the same cells is partly associated with the corresponding detergent-insoluble matrices, we propose that these 2 novel proteins may relate to cell rounding, through a transmembrane modulation involving both surface membrane and cytoskeletal structures.
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Rieber M, Rieber MS, Urbina C, Lira R. 120 and 80 kd detergent-insoluble glycoproteins as markers of differentiation and adhesion in B16 melanoma. Biochem Biophys Res Commun 1986; 140:638-43. [PMID: 3778473 DOI: 10.1016/0006-291x(86)90779-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Surface glycoproteins correlating with cell adhesion and differentiation have now been studied in pigmented and amelanotic B16 melanoma cell monolayers and aggregates, labelled with 3H-glucosamine. Solubilization with the non-ionic detergent octyl glucoside revealed mostly adhesion-related changes, which involved a decrease in 140 and 110 kd glycoproteins in both pigmented and amelanotic cell aggregates. Nevertheless, differentiation-regulated changes were preferentially evident in the remaining detergent-insoluble glycoproteins. Pigmented cell monolayers showed a preferential increase in glycoprotein species of about 120 kd and 80 kd, which were not detected in amelanotic monolayers or in pigmented or amelanotic cell aggregates. Our findings suggest the relevance of these cytoskeleton associated glycoproteins as markers of differentiation and adhesion in melanoma cells.
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Rieber M, Gil F, Rieber MS, Urbina C. Substrate-dependent effect of epidermal growth factor on intercellular adhesion and synthesis of triton-insoluble proteins in human carcinoma A431 cells. Int J Cancer 1986; 37:411-8. [PMID: 3485080 DOI: 10.1002/ijc.2910370313] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Human epidermoid carcinoma A431 cells attach more rapidly to collagen type-I and -IV substrates than to surfaces coated with laminin or fibronectin. The diminished intercellular interaction and rounding up manifested when these cells are exposed to epidermal growth factor (EGF) in tissue culture plastic or collagen films is not shown when the assay is performed on 3-dimensional collagen. In the latter substrate, cells exposed to EGF reveal greater cell cohesion with interdigitations and desmosomal junctions, compared to the limited intercellular interaction detected in similarly treated cells assayed in tissue culture substrate. Although the protein synthesis inhibitor, cycloheximide, did not prevent these EGF-mediated changes, metabolic labelling indicated a substrate-dependent effect of EGF on the synthesis of proteins associated with the Triton-insoluble cytoskeletal matrix. The involvement of cytoskeleton components in the EGF effects on intercellular adhesion was shown by its susceptibility to cytochalasin B, known to disorganize actin-containing microfilaments. Some of the mechanisms of epithelial morphogenesis and the influence of extracellular matrix components on cell-receptor/growth-factor interactions may now be suitably analyzed by examining the EGF effects on A431 cells grown on different substrata.
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