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Wolfe J, Sasson SB, Ron A. Cell pairing and methylation in Tetrahymena thermophila are altered by exogenous homocysteine. Cell Biol Int 2000; 23:619-28. [PMID: 10728573 DOI: 10.1006/cbir.1999.0427] [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: 11/22/2022]
Abstract
Homocysteine is causally associated with birth defects such as spina bifida, and with premature vascular disease. We have investigated the effects of homocysteine on a cell-cell interaction in a fundamental eukaryotic system, the free-living ciliate Tetrahymena. Exogenously added homocysteine inhibits cell pairing in a dose-dependent manner. These effects are exacerbated by adenosine, which by itself has little demonstrable influence on pairing. S-adenosylhomocysteine (SAH) is a product of the reaction between adenosine and homocysteine, and is an inhibitor of methyl transferases. We therefore predicted that protein methylation would be significantly inhibited by homocysteine. A direct test of that hypothesis involved a demonstration that incorporation of an isotopically labeled methyl group from methionine into proteins was significantly reduced by homocysteine. The undermethylated proteins are of low molecular weight, and might correspond to known methylatable signaling proteins. We show that vanadate, an inhibitor of protein phosphatase, also inhibits cell pairing, and that the effects of vanadate and homocysteine are additive. This is the first demonstration that methylation and possibly phosphorylation play a regulatory role in cell-cell interactions in ciliates.
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Ron A, Meisel S, Shapiro-Feinberg M, Klein HO. [Cortical blindness following coronary angiography]. HAREFUAH 2000; 138:279-81, 342. [PMID: 10883110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
Cortical blindness has been occasionally reported as a complication after cerebral angiography, but is rare after coronary angiography. The contrast agent is believed to be responsible for the sudden development of blindness. Although the exact mechanism is unknown, it appears that the contrast agent disrupts the blood brain barrier, mostly in the occipital areas. We report a 77-year-old man who suddenly developed transient, bilateral cortical blindness 4 hours after coronary angiography. Using contrast enhancement, the CT scan showed typical, symmetrical involvement of both occipital lobes. There were no other neurological deficits. Vision and CT findings returned to normal within 48 hours.
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Rapaport R, Harel R, Cohen E, Ron A, Linder E, Pfeiffer LN. Negatively charged quantum well polaritons in a GaAs/AlAs microcavity: An analog of atoms in a cavity. PHYSICAL REVIEW LETTERS 2000; 84:1607-1610. [PMID: 11017579 DOI: 10.1103/physrevlett.84.1607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/1999] [Indexed: 05/23/2023]
Abstract
The negatively charged exciton (X-) is observed to strongly couple with the microcavity- (MC-)confined photons in a GaAs quantum well containing a two-dimensional electron gas with 0<n(e)</=3x10(10) cm(-2). This strong coupling results in a formation of charged polaritons. The coupling strength is found to depend on sqrt[n(e)], in analogy to two-level atoms in a cavity. The analysis of the reflection and photoluminescence spectra shows that X- is strongly admixed with the neutral exciton via their coupling with the MC photons. The linewidth dependence on n(e) indicates that electron-polariton scattering is effective.
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Carrin G, Ron A, Hui Y, Hong W, Tuohong Z, Licheng Z, Shuo Z, Yide Y, Jiaying C, Qicheng J, Zhaoyang Z, Jun Y, Xuesheng L. The reform of the rural cooperative medical system in the People's Republic of China: interim experience in 14 pilot counties. Soc Sci Med 1999; 48:961-72. [PMID: 10192562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
During the 1960's and 1970's the Chinese government encouraged the 'rural cooperative medical systems' (RCMS), in order to ensure access to basic health care among the rural population. There was a break in the development of the RCMS in the early 1980's, as a consequence of market economic reforms. These reforms involved a shift from a communal to a household production system. As a result the collective way of financing rural health care was more or less abandoned. However, the government of the People's Republic of China was aware of the need to provide social protection against health care expenses. In March 1994 the government initiated a project to reestablish the RCMS. This project was implemented on a pilot basis in 14 counties of seven provinces. The reestablishment of the RCMS would be guided by the basic principles of health insurance. In October 1995, a first mid-term evaluation of the RCMS Project was held. One of the major research questions concerned the extent to which the RCMS had reduced the risk of paying health care bills that would otherwise be a burden on families. This article addresses this question and assesses the results obtained after two years of RCMS experimental work. A general finding is that the population structure by occupation and income varies, and that the RCMS has adapted itself to this variety. It is also confirmed that the burden of health care costs on families was reduced, more so in some counties than in others, but this reduction has been modest. The research results indicate that there is ample room for improvement. The outlook is hopeful, however. At the national level, there is now systematic thinking about RCMS. The current RCMS work is also having a considerable influence on other counties that are keen to reestablish the RCMS.
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Abstract
In poor rural communities, access to basic health care is often severely limited by inadequate supply as well as financial barriers to seeking care. National policies may introduce social health insurance, but these are likely to begin with the salaried public and private sector workers while the informal sector population may be the last to be covered. Community initiatives to generate health care financing require a complex development process. This paper covers attempts to develop such schemes in rural populations in Guatemala and the Philippines through non-government organizations and notes the major factors which have contributed to unequal progress in the two schemes. The scheme of the Association por Salud de Barillas (ASSABA) in Guatemala was not sufficiently established as an administrative body at the conceptual stage and there was no clear national policy on health care financing. By the time the necessary action was taken, local conflicts hindered progress. In the Philippines, the ORT Health Plus Scheme (OHPS) was implemented during the period of legislation of a national health insurance act. The appraisal after three years of operation shows that OPHS has made health care affordable and accessible to the target population, composed mainly of low and often unstable income families in rural areas. The major success factors are probably the administrative structure provided by a cooperative and controls in the delivery system and in expenditures, through the salaried primary health care team, referral process and the capitation agreement for hospital-based services. The proliferation of such schemes could benefit from national guidelines, a formal accreditation process and an umbrella organization to provide assistance in design, training and information services, involving government, non-government and academic institutions as an integral part of the development process.
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Gonen R, Degani S, Ron A. Prediction of successful induction of labor: comparison of transvaginal ultrasonography and the Bishop score. EUROPEAN JOURNAL OF ULTRASOUND : OFFICIAL JOURNAL OF THE EUROPEAN FEDERATION OF SOCIETIES FOR ULTRASOUND IN MEDICINE AND BIOLOGY 1998; 7:183-7. [PMID: 9700213 DOI: 10.1016/s0929-8266(98)00042-1] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE To determine whether transvaginal ultrasonography of the cervix before induction of labor is a better predictor of successful induction than the Bishop score. STUDY DESIGN Eighty-six consecutive patients scheduled for induction of labor underwent digital cervical examination followed by transvaginal ultrasonography to measure cervical length and to determine the presence of wedging. Patients were induced with either oxytocin or intracervical prostaglandin E2 gel followed by oxytocin when required. The agent for induction was selected on the basis of the digital examination. The primary outcome criteria were successful induction and the duration of labor. RESULTS Successful induction and the duration of labor were significantly associated with the Bishop score and cervical length. Cervical wedging was associated only with successful induction. However, in a logistic regression model that included these parameters as independent variables, only the Bishop score and parity were significantly correlated with successful induction and the duration of labor. CONCLUSIONS Transvaginal ultrasonographic evaluation of the cervix before induction of labor does not improve the prediction of cervical inducibility obtained by the Bishop score.
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Abstract
Emphasis on hospital mortality as a monitoring tool has raised concerns about the validity of mortality rates as a measure of quality of care. An indepth review of all mortalities at Beth Israel Medical Center was conducted from 1988 through 1993. Clinical issues identified from chart review were referred for departmental physician peer review, and quarterly reports of trends and issues were disseminated to all levels of the institution. Mortality rates declined 21% over the 6 years, from 3.3% to 2.6% of all discharges. Clinical quality issues were identified in less than 3% of all mortalities. The majority of problems were related to delays and appropriateness of treatment (57% of quality issues). The review program identified specific hospital processes for improvement, and, more importantly, created a "watchful concern" about quality-of-care issues throughout the hospital.
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Gekhtman D, Cohen E, Ron A, Pfeiffer LN. Charged and neutral exciton phase formation in the magnetically quantized two-dimensional electron gas. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:10320-10323. [PMID: 9984813 DOI: 10.1103/physrevb.54.10320] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Manassen A, Cohen E, Ron A, Linder E, Pfeiffer LN. Exciton and trion spectral line shape in the presence of an electron gas in GaAs/AlAs quantum wells. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:10609-10613. [PMID: 9984857 DOI: 10.1103/physrevb.54.10609] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ashkinadze BM, Tsidilkovski E, Linder E, Cohen E, Ron A, Pfeiffer LN. Electron-assisted exciton transfer and long-lived electrons and holes in GaAs/AlxGa1-xAs quantum wells. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:8728-8736. [PMID: 9984551 DOI: 10.1103/physrevb.54.8728] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Zhang TB, Marshall TC, LaPointe MA, Hirshfield JL, Ron A. Microwave inverse C-caronerenkov accelerator. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1996; 54:1918-1929. [PMID: 9965275 DOI: 10.1103/physreve.54.1918] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Gekhtman D, Kash JA, Cohen E, Ron A. Optical observation of impurity localized states at the edges of Landau subbands in doped quantum wells. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:2756-2762. [PMID: 9986128 DOI: 10.1103/physrevb.54.2756] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Harel R, Cohen E, Linder E, Ron A, Pfeiffer LN. Absolute transmission, reflection, and absorption studies in GaAs/AlAs quantum wells containing a photoexcited electron gas. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:7868-7875. [PMID: 9982237 DOI: 10.1103/physrevb.53.7868] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Kozhevnikov M, Ashkinadze BM, Cohen E, Ron A. Low-temperature electron mobility studied by cyclotron resonance in ultrapure GaAs crystals. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:17165-17171. [PMID: 9981143 DOI: 10.1103/physrevb.52.17165] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Livescu G, Chirovsky LM, Mullally T, Ron A. Transmission of 1-Gbit / s data patterns through smart pixels by use of picosecond laser pulses. OPTICS LETTERS 1995; 20:2324. [PMID: 19865207 DOI: 10.1364/ol.20.002324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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Bortman D, Ron A. Bistability in a quantum nonlinear oscillator. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1995; 52:3316-3322. [PMID: 9912617 DOI: 10.1103/physreva.52.3316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Kozhevnikov M, Ashkinadze BM, Cohen E, Ron A. Self-oscillations at photoinduced impurity breakdown in GaAs. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:4855-4863. [PMID: 9981669 DOI: 10.1103/physrevb.52.4855] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ashkinadze BM, Linder E, Cohen E, Ron A, Pfeiffer LN. Free-carrier effect on exciton dynamics in GaAs/AlxGa1-xAs quantum wells. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:1938-1941. [PMID: 9978921 DOI: 10.1103/physrevb.51.1938] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Blickstein I, Ron A. Can placental surface area and neonatal weight be predicted from placental surface measurements? Preliminary observations on normal-term pregnancies. Gynecol Obstet Invest 1995; 40:253-6. [PMID: 8586307 DOI: 10.1159/000292347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVE To evaluate the relations between chorionic plate measurements and neonatal weight as prerequisites for possible prediction of fetal weight using antenatal placental measurements. METHODS We examined freshly delivered placentas. The surface area (chorionic plate) was measured using millimeter paper, and the two longest diameters (at right angles to each other) were determined (L1 and L2). The mean longest diameter [Lm = (L1 + L2)/2] was calculated. The relation of these diameters to neonatal and placental weight was studied. RESULTS We examined 57 randomly selected placentas after normal pregnancy and delivery. The three chorionic plate diameters significantly correlated with the surface area and the placental and neonatal weights. The strongest correlation (r = 0.94; p < 10(-6) was found between Lm and placental surface area. CONCLUSIONS Our preliminary results suggest that chorionic plate measurements may be suitable to predict placental surface area and neonatal birth weight in normal-term pregnancies. Further studies to verify prospectively these relations at various gestational ages and in cases of abnormal fetal growth are required.
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Frommer A, Ron A, Cohen E, Kash JA, Pfeiffer LN. Dynamics and spin relaxation of excitons in GaAs/AlxGa1-xAs quantum wells. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:11833-11839. [PMID: 9975321 DOI: 10.1103/physrevb.50.11833] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ron A, Goldberg IB, Stein J, Manson ST, Pratt RH, Yin RY. Relativistic, retardation, and multipole effects in photoionization cross sections: Z, n, and l dependence. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1994; 50:1312-1320. [PMID: 9911023 DOI: 10.1103/physreva.50.1312] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Frommer A, Cohen E, Ron A, Kash A, Pfeiffer LN. Long-lived polarized photoluminescence from separately localized e-h pairs in GaAs/AlxGa1-xAs quantum wells. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:2935-2938. [PMID: 10011135 DOI: 10.1103/physrevb.49.2935] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Garini Y, Ehrenfreund E, Cohen E, Ron A, Law K, Merz JL, Gossard AC. Optically induced intersubband absorption in the presence of a two-dimensional electron gas in quantum wells. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:4456-4459. [PMID: 10008921 DOI: 10.1103/physrevb.48.4456] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Frommer A, Cohen E, Ron A, Pfeiffer LN. Linear and circular polarizations of exciton luminescence in GaAs/AlxGa1-xAs quantum wells. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:2803-2806. [PMID: 10008686 DOI: 10.1103/physrevb.48.2803] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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