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Finkelstein A, Kunis G, Berkutzki T, Ronen A, Krivoy A, Yoles E, Last D, Mardor Y, Van Shura K, McFarland E, Capacio BA, Eisner C, Gonzales M, Gregorowicz D, Eisenkraft A, McDonough JH, Schwartz M. Immunomodulation by poly-YE reduces organophosphate-induced brain damage. Brain Behav Immun 2012; 26:159-69. [PMID: 21925261 DOI: 10.1016/j.bbi.2011.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 09/01/2011] [Indexed: 10/17/2022] Open
Abstract
Accidental organophosphate poisoning resulting from environmental or occupational exposure, as well as the deliberate use of nerve agents on the battlefield or by terrorists, remain major threats for multi-casualty events, with no effective therapies yet available. Even transient exposure to organophosphorous compounds may lead to brain damage associated with microglial activation and to long-lasting neurological and psychological deficits. Regulation of the microglial response by adaptive immunity was previously shown to reduce the consequences of acute insult to the central nervous system (CNS). Here, we tested whether an immunization-based treatment that affects the properties of T regulatory cells (Tregs) can reduce brain damage following organophosphate intoxication, as a supplement to the standard antidotal protocol. Rats were intoxicated by acute exposure to the nerve agent soman, or the organophosphate pesticide, paraoxon, and after 24 h were treated with the immunomodulator, poly-YE. A single injection of poly-YE resulted in a significant increase in neuronal survival and tissue preservation. The beneficial effect of poly-YE treatment was associated with specific recruitment of CD4(+) T cells into the brain, reduced microglial activation, and an increase in the levels of brain derived neurotrophic factor (BDNF) in the piriform cortex. These results suggest therapeutic intervention with poly-YE as an immunomodulatory supplementary approach against consequences of organophosphate-induced brain damage.
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Affiliation(s)
- Arseny Finkelstein
- Department of Neurobiology, The Weizmann Institute of Science, Rehovot 76100, Israel
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Finkelstein A, Kunis G, Seksenyan A, Ronen A, Berkutzki T, Azoulay D, Koronyo-Hamaoui M, Schwartz M. Abnormal changes in NKT cells, the IGF-1 axis, and liver pathology in an animal model of ALS. PLoS One 2011; 6:e22374. [PMID: 21829620 PMCID: PMC3149057 DOI: 10.1371/journal.pone.0022374] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 06/24/2011] [Indexed: 11/27/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a rapidly progressing fatal neurodegenerative disorder characterized by the selective death of motor neurons (MN) in the spinal cord, and is associated with local neuroinflammation. Circulating CD4+ T cells are required for controlling the local detrimental inflammation in neurodegenerative diseases, and for supporting neuronal survival, including that of MN. T-cell deficiency increases neuronal loss, while boosting T cell levels reduces it. Here, we show that in the mutant superoxide dismutase 1 G93A (mSOD1) mouse model of ALS, the levels of natural killer T (NKT) cells increased dramatically, and T-cell distribution was altered both in lymphoid organs and in the spinal cord relative to wild-type mice. The most significant elevation of NKT cells was observed in the liver, concomitant with organ atrophy. Hepatic expression levels of insulin-like growth factor (IGF)-1 decreased, while the expression of IGF binding protein (IGFBP)-1 was augmented by more than 20-fold in mSOD1 mice relative to wild-type animals. Moreover, hepatic lymphocytes of pre-symptomatic mSOD1 mice were found to secrete significantly higher levels of cytokines when stimulated with an NKT ligand, ex-vivo. Immunomodulation of NKT cells using an analogue of α-galactosyl ceramide (α-GalCer), in a specific regimen, diminished the number of these cells in the periphery, and induced recruitment of T cells into the affected spinal cord, leading to a modest but significant prolongation of life span of mSOD1 mice. These results identify NKT cells as potential players in ALS, and the liver as an additional site of major pathology in this disease, thereby emphasizing that ALS is not only a non-cell autonomous, but a non-tissue autonomous disease, as well. Moreover, the results suggest potential new therapeutic targets such as the liver for immunomodulatory intervention for modifying the disease, in addition to MN-based neuroprotection and systemic treatments aimed at reducing oxidative stress.
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Affiliation(s)
- Arseny Finkelstein
- Department of Neurobiology, The Weizmann Institute of Science, Rehovot, Israel
| | - Gilad Kunis
- Department of Neurobiology, The Weizmann Institute of Science, Rehovot, Israel
| | - Akop Seksenyan
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Ayal Ronen
- Department of Neurobiology, The Weizmann Institute of Science, Rehovot, Israel
| | - Tamara Berkutzki
- Department of Veterinary Resources, The Weizmann Institute of Science, Rehovot, Israel
| | - David Azoulay
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Maya Koronyo-Hamaoui
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Michal Schwartz
- Department of Neurobiology, The Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
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Rein D, Cohen Y, Ronen A, Shuster K, Zussman E. Application of gentle annular gas veil for electrospinning of polymer solutions and melts. POLYM ENG SCI 2009. [DOI: 10.1002/pen.21273] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Kela-Madar N, de Rosbo NK, Ronen A, Mor F, Ben-Nun A. Autoimmune spread to myelin is associated with experimental autoimmune encephalomyelitis induced by a neuronal protein, β-Synuclein. J Neuroimmunol 2009; 208:19-29. [DOI: 10.1016/j.jneuroim.2008.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 12/16/2008] [Accepted: 12/22/2008] [Indexed: 01/07/2023]
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Shechter R, Ronen A, Rolls A, London A, Bakalash S, Young MJ, Schwartz M. Toll-like receptor 4 restricts retinal progenitor cell proliferation. J Exp Med 2008. [DOI: 10.1084/jem20512oia26] [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: 11/04/2022] Open
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Shechter R, Ronen A, Rolls A, London A, Bakalash S, Young MJ, Schwartz M. Toll-like receptor 4 restricts retinal progenitor cell proliferation. ACTA ACUST UNITED AC 2008; 183:393-400. [PMID: 18981228 PMCID: PMC2575781 DOI: 10.1083/jcb.200804010] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Retinal neurogenesis ceases by the early postnatal period, although retinal progenitor cells (RPCs) persist throughout life. In this study, we show that in the mammalian eye, the function of Toll-like receptor 4 (TLR4) extends beyond regulation of the innate immune response; it restricts RPC proliferation. In TLR4-deficient mice, enhanced proliferation of cells reminiscent of RPCs is evident during the early postnatal period. In vitro experiments demonstrate that TLR4 acts as an intrinsic regulator of RPC fate decision. Increased TLR4 expression in the eye correlates with the postnatal cessation of cell proliferation. However, deficient TLR4 expression is not sufficient to extend the proliferative period but rather contributes to resumption of proliferation in combination with growth factors. Proliferation in vivo is inhibited by both MyD88-dependent and -independent pathways, similar to the mechanisms activated by TLR4 in immune cells. Thus, our study attributes a novel role to TLR4 as a negative regulator of RPC proliferation.
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Affiliation(s)
- Ravid Shechter
- Department of Neurobiology, Weizmann Institute of Science, 76100 Rehovot, Israel
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Birger R, Abd-ElHadi F, Ronen A, Cohen E, Ankorion Y, Najjar A, Moreno J. OLIVE HARVESTVANT, A NEW HARVEST-AID FORMULATION FOR IMPROVING FRUIT ABSCISSION AND MECHANICAL HARVESTING. Acta Hortic 2008:257-263. [DOI: 10.17660/actahortic.2008.791.36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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Rolls A, Shechter R, London A, Ziv Y, Ronen A, Levy R, Schwartz M. Toll-like receptors modulate adult hippocampal neurogenesis. Nat Cell Biol 2007; 9:1081-8. [PMID: 17704767 DOI: 10.1038/ncb1629] [Citation(s) in RCA: 449] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Accepted: 07/16/2007] [Indexed: 12/19/2022]
Abstract
Neurogenesis - the formation of new neurons in the adult brain - is considered to be one of the mechanisms by which the brain maintains its lifelong plasticity in response to extrinsic and intrinsic changes. The mechanisms underlying the regulation of neurogenesis are largely unknown. Here, we show that Toll-like receptors (TLRs), a family of highly conserved pattern-recognizing receptors involved in neural system development in Drosophila and innate immune activity in mammals, regulate adult hippocampal neurogenesis. We show that TLR2 and TLR4 are found on adult neural stem/progenitor cells (NPCs) and have distinct and opposing functions in NPC proliferation and differentiation both in vitro and in vivo. TLR2 deficiency in mice impaired hippocampal neurogenesis, whereas the absence of TLR4 resulted in enhanced proliferation and neuronal differentiation. In vitro studies further indicated that TLR2 and TLR4 directly modulated self-renewal and the cell-fate decision of NPCs. The activation of TLRs on the NPCs was mediated via MyD88 and induced PKCalpha/beta-dependent activation of the NF-kappaB signalling pathway. Thus, our study identified TLRs as players in adult neurogenesis and emphasizes their specified and diverse role in cell renewal.
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Affiliation(s)
- Asya Rolls
- Department of Neurobiology, The Weizmann Institute of Science, 76100 Rehovot, Israel
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Abstract
A major achievement of mechanism design theory is a general method for the construction of truthful mechanisms called VCG (Vickrey, Clarke, Groves). When applying this method to complex problems such as combinatorial auctions, a difficulty arises: VCG mechanisms are required to compute optimal outcomes and are, therefore, computationally infeasible. However, if the optimal outcome is replaced by the results of a sub-optimal algorithm, the resulting mechanism (termed VCG-based) is no longer necessarily truthful. The first part of this paper studies this phenomenon in depth and shows that it is near universal. Specifically, we prove that essentially all reasonable approximations or heuristics for combinatorial auctions as well as a wide class of cost minimization problems yield non-truthful VCG-based mechanisms. We generalize these results for affine maximizers.
The second part of this paper proposes a general method for circumventing the above problem. We introduce a modification of VCG-based mechanisms in which the agents are given a chance to improve the output of the underlying algorithm. When the agents behave truthfully, the welfare obtained by the mechanism is at least as good as the one obtained by the algorithm's output. We provide a strong rationale for truth-telling behavior. Our method satisfies individual rationality as well.
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Verri G, Barkai R, Bordeanu C, Gopher A, Hass M, Kaufman A, Kubik P, Montanari E, Paul M, Ronen A, Weiner S, Boaretto E. Flint mining in prehistory recorded by in situ-produced cosmogenic 10Be. Proc Natl Acad Sci U S A 2004; 101:7880-4. [PMID: 15148365 PMCID: PMC419525 DOI: 10.1073/pnas.0402302101] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The development of mining to acquire the best raw materials for producing stone tools represents a breakthrough in human technological and intellectual development. We present a new approach to studying the history of flint mining, using in situ-produced cosmogenic 10Be concentrations. We show that the raw material used to manufacture flint artifacts approximately 300,000 years old from Qesem Cave (Israel) was most likely surface-collected or obtained from shallow quarries, whereas artifacts of the same period from Tabun Cave (Israel) were made of flint originating from layers 2 or more meters deep, possibly mined or quarried by humans.
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Affiliation(s)
- G Verri
- Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Wiesman Z, Luber M, Ronen A, Markus A. FERTI-VANT - A NEW NONDESTRUCTIVE AND LONG-LASTING IN VIVO DELIVERY SYSTEM FOR FOLIAR NUTRIENTS. ACTA ACUST UNITED AC 2002. [DOI: 10.17660/actahortic.2002.594.78] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Laukhin SA, Ronen A, Pospelova G, Sharonova Z, Ranov VA, Burdukiewicz J, Volgina V, Tsatskin A. New data on the Geology and Geochronology of the Lower Palaeolithic Site Bizat Ruhama in the Southern Levant. ACTA ACUST UNITED AC 2001. [DOI: 10.3406/paleo.2001.4720] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Abstract
DNA repair systems are essential for the maintenance of genome integrity. Consequently, the disregulation of repair genes can be expected to be associated with significant, detrimental health effects, which can include an increased prevalence of birth defects, an enhancement of cancer risk, and an accelerated rate of aging. Although original insights into DNA repair and the genes responsible were largely derived from studies in bacteria and yeast, well over 125 genes directly involved in DNA repair have now been identified in humans, and their cDNA sequence established. These genes function in a diverse set of pathways that involve the recognition and removal of DNA lesions, tolerance to DNA damage, and protection from errors of incorporation made during DNA replication or DNA repair. Additional genes indirectly affect DNA repair, by regulating the cell cycle, ostensibly to provide an opportunity for repair or to direct the cell to apoptosis. For about 70 of the DNA repair genes listed in Table I, both the genomic DNA sequence and the cDNA sequence and chromosomal location have been elucidated. In 45 cases single-nucleotide polymorphisms have been identified and, in some cases, genetic variants have been associated with specific disorders. With the accelerating rate of gene discovery, the number of identified DNA repair genes and sequence variants is quickly rising. This report tabulates the current status of what is known about these genes. The report is limited to genes whose function is directly related to DNA repair.
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Affiliation(s)
- A Ronen
- Centre for Environmental Health, University of Victoria, Victoria, British Columbia, Canada.
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Laukhin SA, Pospelova GA, Ronen A, Ranov VA, Sharonova ZV, Volgina VA, Burdukevich I, Tsatskin A. [Most ancient migration of paleolytic peoples from Africa to Eurasia along the shore of the Mediterranean Sea: paleomagnetic evidence]. Dokl Akad Nauk 1999; 369:396-9. [PMID: 10613247] [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: 02/15/2023]
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Abstract
We treated transformed human fibroblasts with diphtheria toxin (DT) and isolated 40 single cells that were toxin resistant but unable to propagate. In 13 of them toxin resistance was associated with the presence of one or more aberrant transcripts of the structural gene for elongation factor 2 (EF-2). cDNA obtained from these transcripts had 164-447 bp-long deletions. Each of these deletions was associated with 2-8 base pairs-long repeats at its breakpoints. Only 10 out of 16 cDNA deletions were associated with presumed exon junctions. A role is suggested for errors in transcription in producing the aberrant transcripts which gave rise to the deletion-bearing cDNA species.
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Affiliation(s)
- A Ronen
- Department of Genetics, Hebrew University, Jerusalem, Israel.
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Ronen A. [We disown death]. Sygeplejersken 1991; 91:13. [PMID: 1803562] [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: 12/28/2022]
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Goldman M, Gilad D, Ronen A, Melloul A. Mapping of seawater intrusion into the coastal aquifer of Israel by the time domain electromagnetic method. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0016-7142(91)90046-f] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
The autoradiographic assay (AR assay) for P. aeruginosa exotoxin A (PE) resistance in cultured mouse fibroblasts detects mutants able to synthesize proteins in the presence of the toxin, presumably due to mutations in the structural gene for elongation factor 2 (EF-2). Detection by the AR assay of PER cells is independent of their ability to divide. The frequencies of both spontaneous and mutagen-induced PER cells are higher than those detected by the conventional colony assay. Examination of phenotypic expression times in the PER cells, and of their in situ proliferation, reveals that this higher sensitivity of the AR assay is due to its ability to detect cells in which the PER mutation prevents proliferation, thus escaping detection by the colony assay. Expression of the mutant phenotype in the PER cells detected in the AR assay after mutagenesis with ethyl methanesulfonate (EMS) follows a pattern similar to that observed in the colony assay, reaching a maximum in 3 days, and then remaining constant for at least 4 more. After treatment with X rays (which fail to induce PER mutants in the colony assay), the frequency of PER cells detected in the AR assay also reaches a maximum on day 3, but then declines sharply, returning to the spontaneous level on day 7. In the absence of PE, the majority of the spontaneous or mutagen-induced PER cells detected in the AR assay are either incapable of dividing at all, or capable of undergoing a limited number of cell divisions to produce micro-colonies. Only few of them may continue to grow into 'full-size' colonies comparable to those detected in the colony assay. In the presence of the toxin, the proportion of PER cells which are able to divide is even smaller, and that of cells able to form full-sized PER colonies detectable in the AR assay is comparable to the results obtained in the conventional colony assay. We presume that the lethality of the PER mutations in the cells detected by the AR assay is due to abnormal protein synthesis resulting from the same mutational change that made these cells resistant to PE. While incapable of supporting colony formation, and hence detection by the colony assay, such abnormal protein synthesis still allows the detection of the mutant cells by the AR assay.
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Affiliation(s)
- M Tiah
- Department of Genetics, Hebrew University of Jerusalem, Israel
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Abstract
A review of 77 neonates who presented with congenital talipes equinovarus over a seven-year period revealed an increase in the condition amongst babies born in the winter quarter. This finding was particularly apparent among the less severe cases of club-foot. Possible reasons for this seasonal variation are discussed.
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Affiliation(s)
- G A Pryor
- Addenbrooke's Hospital, Cambridge, England
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Ley CC, Villar RN, Ronen A. Splinting for CDH: temporary splinting for the neonate. Prosthet Orthot Int 1990; 14:85-6. [PMID: 2235306 DOI: 10.3109/03093649009080328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A simple method of maintaining hip abduction in the neonate with suspected congenital hip instability is described. Clinical observations and parental impressions are initially favourable.
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Affiliation(s)
- C C Ley
- Department of Orthopaedic Surgery, Addenbrooke's Hospital, Cambridge, United Kingdom
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Tiah M, Ronen A. Autoradiographic detection of mutation to exotoxin-A resistance in mouse fibroblasts treated with ethyl methanesulfonate, X-rays and ultraviolet light. Mutat Res 1989; 213:205-15. [PMID: 2503718 DOI: 10.1016/0027-5107(89)90152-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
P. aeruginosa exotoxin-A (PE) blocks protein synthesis in mammalian cells by inactivating elongation factor 2 (EF-2). Toxin-resistant mutant cells can be detected autoradiographically, in cultures grown on microscope coverslips in the presence of PE, and then exposed to [3H]leucine. The frequency of PE-resistant cells detected by the autoradiographic assay in non-mutagenized cells of the established mouse cell line LTKA is 9.7 +/- 0.6 X 10(-5). Upon treatment with ethyl methanesulfonate (EMS), X-rays or ultraviolet (UV) light it increases in a dose-dependent fashion. The mutational nature of the resistance detected by the assay is indicated by its clonal inheritance, and by the dose-dependent increase in the frequency of resistant cells after mutagenesis. On the basis of the high frequency of PE-resistant cells detected by the autoradiographic assay, and their cross-resistance to diphtheria toxin (DT), we suggest that the PE-resistant mutants detected by the autoradiographic assay are of class II, i.e., they are altered in the structural gene for EF-2. The autoradiographic assay for PE resistance is similar to that for DT resistance, but is applicable also to mouse cells, which are naturally resistant to DT. Being independent of colony formation, the autoradiographic assay for PE resistance can be used with non-dividing cells, either in vitro or in vivo.
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Affiliation(s)
- M Tiah
- Department of Genetics, Hebrew University of Jerusalem, Israel
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Abstract
A lightweight, washable, and easily adjusted splint for the congenitally dislocated hip, designed to improve maternal compliance, is described. Observations are currently scientifically uncontrolled, though initial impressions are favourable.
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Affiliation(s)
- R N Villar
- Department of Orthopaedic Surgery, Addenbrooke's Hospital, Cambridge, United Kingdom
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Abstract
The rat hepatocarcinogen nitrosodimethylamine and the esophageal carcinogens nitrosomethylbenzylamine and nitrosomethylamylamine were shown to produce chromosomal damage, as manifested by micronucleus formation, in their target tissues. There was cross-reactivity in the two tissues, however, at high dose levels. Nitrosodiethylamine, which produces tumors in both the liver and esophagus in the rat, also produced micronuclei in both tissues.
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Ronen A, Gingerich JD, Duncan AM, Heddle JA. Autoradiographic assay of mutants resistant to diphtheria toxin in mammalian cells in vitro. Proc Natl Acad Sci U S A 1984; 81:6124-8. [PMID: 6592605 PMCID: PMC391872 DOI: 10.1073/pnas.81.19.6124] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Diphtheria toxin kills mammalian cells by ribosylating elongation factor 2, a protein factor necessary for protein synthesis. The frequency of cells able to form colonies in the presence of the toxin can be used as an assay for mutation to diphtheria toxin resistance. We report here that resistance to diphtheria toxin can also be detected autoradiographically in cells exposed to [3H]leucine after treatment with the toxin. In cultures of Chinese hamster ovary cells, the frequency of such resistant cells is increased by exposure of the cells to gamma-rays, ultraviolet light, ethylnitrosourea, mitomycin c, ethidium bromide, and 5-bromo-2'-deoxyuridine in a dose- and time-dependent manner. The resistant cells form discrete microcolonies if they are allowed to divide several times before intoxication, which indicates that they are genuine mutants. The assay is potentially adaptable to any cell population that can be intoxicated with diphtheria toxin and labeled with [3H]leucine, whether or not the cells can form colonies. It may be useful, therefore, for measuring mutation rates in slowly growing or nondividing cell populations such as breast, brain, and liver, as well as in cells that do divide but cannot be readily cloned, such as the colonic epithelium.
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Ronen A, Heddle JA. Site-specific induction of nuclear anomalies (apoptotic bodies and micronuclei) by carcinogens in mice. Cancer Res 1984; 44:1536-40. [PMID: 6704967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The usefulness of nuclear anomalies (NA) as a short-term test for indication of carcinogens in the mouse colon has been suggested previously by experiments in which colon-specific carcinogens induced NA in the colon, whereas non-colon carcinogens were, in general, impotent in that organ. We have extended this work to other sites in the digestive tract of female C57BL/6 mice treated with gamma-rays, 1,2-dimethylhydrazine dihydrochloride, or N-methylnitrosourea. Each agent induced NA at all of the sites examined. The frequency of NA at different times after treatment depended upon both the agent used and the site examined. 1,2-Dimethylhydrazine dihydrochloride (which is known to induce tumors predominantly in the colon) induces NA with the highest efficiency (relative to gamma-rays) in the descending colon. N-Methylnitrosourea (which induces tumors mainly in the forestomach) induces NA with the highest efficiency in the forestomach. These results further support the usefulness of the assay in that the frequency of NA produced at the various sites by 1,2-dimethylhydrazine dihydrochloride and N-methylnitrosourea correlates with that found in the carcinogenicity studies.
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Abstract
The appearance of apoptosis has been used as an index of carcinogen-induced damage incurred by the intestinal epithelium. Here we report that the cytotoxic response elicited by gamma radiation in the duodenal and colonic epithelium of the mouse is markedly affected by the time of day at which the animals are irradiated or sampled. The diurnal pattern in radiosensitivity of the crypt cells, as measured by the appearance of apoptosis is reflective of circadian rhythms in mouse intestinal cells. Circadian effects should therefore be considered when interpreting apoptosis data obtained at one time point only or when comparing data obtained at different times of the day.
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Abstract
A test system is described for investigating friction and wear of hydrodynamic bearings under cyclical dynamic loading conditions with contaminant abrasive particles in the oil supply. Dynamic loading on the test bearing is synchronized with the shaft rotation, so that the oil film thickness history can be determined from the measured shaft orbit for any point on the shaft and liner periphery. Either clean or contaminated oil can be supplied to the test bearing from two separate oil supply systems. Experimental results obtained for six shaft/liner bearing material combinations were similar to those previously obtained for static loading. The friction and wear behavior were found to depend on the relative hardnesses of the shaft and liner. A larger shaft-to-liner hardness ratio generally resulted in more shaft wear and less liner wear. This is attributed to an increased tendency for abrasive particles to partially embed in the liner and cut the shaft when the shaft is harder and/or the liner is softer. With partial embedding, high bearing friction indicative of continuing abrasion persists after changing from contaminated to clean oil.
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Affiliation(s)
- A. Ronen
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - S. Malkin
- Technion-Israel Institute of Technology, Haifa 32000, Israel
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Abstract
An investigation is reported on the wear of hydrodynamic bearings by contaminant particles in the oil under dynamic loading conditions. A test bearing rig was developed to dynamically simulate an automotive connecting rod engine bearing, and the contaminant additions were of the types normally used for testing of automotive oil filters and air cleaners. Shaft and linear wear for clean and contaminated oil were measured both in terms of dimensional changes and weight loss at two different rotating speeds. As compared with clean oil, both shaft and linear wear were found to increase by typically a factor of 20 when running with the contaminated oil. A direct correlation was found between the local oil film thickness history and wear intensity for both the clean and contaminated oil. The wear tended to increase steeply at those locations where the oil film was smaller for a greater portion of the operating cycle.
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Affiliation(s)
- A. Ronen
- Technion - Israel Institute of Technology, Haifa, Israel
| | - S. Malkin
- Technion - Israel Institute of Technology, Haifa, Israel
| | - K. Loewy
- Technion - Israel Institute of Technology, Haifa, Israel
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33
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Abstract
The effects of neighbouring base pairs and of temperature on mutation frequencies were measured at nonsense sites in the T4rII region. 2AP-induced AT leads to GC transition frequencies are insensitive to nearest-neighbour effects, while 5BU-induced ones are promoted by GC neighbours on the 5' side. The effect of temperature on 2AP- and 5BU-induced mutation frequencies shows no simple dependence on nearest neighbours. These results are incompatible with a unitary mechanism as explanation for the effects of nearest neighbours and temperature on base-analogue-induced mutagenesis.
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34
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35
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Abstract
Spontaneous, 2-aminopurine- and 5-bromouracil-induced mutations at six rII nonsense codons were studied in phage T4 strains possessing wild-type and mutant gene 43 alleles. The mutation pathways studied included interconversions and reversions of nonsense codons. The tsCB87 allele, which specifies an antimutator DNA polymerase, reduced base-analogue-induced mutation frequencies along all pathways. However, GC base pairs were less affected than AT base pairs. The frequency of spontaneous UAA leads to UAG conversions was also reduced by tsCB87, but that of spontaneous UAA leads to UAG UGA conversions was often increased. Mutation in the presence of the mutator allele tsL56 was increased along all pathways, with no preference for either AT or GC base pairs. Mutation frequencies in the presence of the two mutant DNA polymerases were highly variable. A strong correlation was found between 2-aminopurine-induced mutation frequencies in ts+ tsCB87 phage along the reversion and UAA changed to UAG (but not UAA changed to UGA) pathways.
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36
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37
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Abstract
The frequencies of 2-aminopurine- and 5-bromouracil-induced A:T leads to G:C transitions were compared at nonsense sites throughout the rII region of bacteriophage T4. These frequencies are influenced both by adjacent base pairs within the nonsense codons and by extracodonic factors. Following 2AP treatment, they are high in amber (UAG) and lower in opal (UGA) codons than in allelic ochre (UAA) codons. In general, 5BU-induced transitions are more frequent in both amber and opal codons than in the allelic ochre codons. 2AP- and 5BU-induced transition frequencies in the first and third positions of opal codons are correlated with those in the corresponding positions of the allelic ochre codons. Similarly, the frequencies of 2AP-induced transition in the first and second positions of amber codons and their ochre alleles are correlated. However, there is little correlation between the frequencies of 5BU-induced transitions in the first and second positions of allelic amber and ochre codons.
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38
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Abstract
SUMMARYTemperature-sensitive mutants in genes 12 and 18 of phage P22 show recessive DNA-negative phenotypes, but dominant integration-negative phenotypes. In contrast, am mutants in genes 12 and 18 are recessive for both DNA synthesis and lysogeny. The data are interpreted to indicate that the active forms of these two gene products are multimers.
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39
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Abstract
In 14 sites in the T4rII region, spontaneous and induced interconversions of ochre (UAA) and opal (UGA) alleles, as well as the reversion of the nonsense sites to r+, were studied. The mutagens employed were 2-aminopurine (2AP), 5-bromouracil (5BU), N-methyl-N'-nitro-N-nitrosoguanidine (NTG) and hydroxylamine (HA). With the test system employed, mutagen specificity (i.e., the preferential induction of A: T leads to G: C or G: C leads to A: T mutation at a given site) can be studied. Simultaneously, the response of similar base pairs at various locations in the same or in different nucleotide triplets throughout the rII region, to a given mutagen, can be compared. 2-Aminopurine can induce transitions of both A: T and G: C base pairs at high rates. This mutagen shows no preference for either direction. Furthermore, there is a correlation between the response to 2AP of an A: T pair occupying a given site, and that of a G: C pair occupying the same site. NTG and HA induce G: C leads to A: T transitions almost exclusively. However, there is a correlation between the low rates of A: T leads to G: C transition induced in each of the various sites by these mutagens and those of G: C leads to A: T. 5-Bromouracil induces transitions from G: C to A: T more readily than from A: T to G: C. With 5BU-induced mutation, there is no correlation between the rates of G: C leads to A: T transitions and those of A: T leads to G: C. In UAA sites, all three adenine:thymidine paris respond to 2AP mutagenesis in a similar pattern, In each position in the triplet, response to 2 AP is correlated with that to 5BU. In UGA sites, there are correlations among the spontaneous as well as the 2AP-, HA- and NTG-induced transition rates. 5BU-induced transition rates are usually not correlated with those induced by other mutagens or with the sponatneous ones.
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40
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Lavi U, Nattenberg A, Ronen A, Marcus M. Bacillus subtilis DNA polymerase III is required for the replication of the virulent bacteriophage phi e. J Virol 1974; 14:1337-42. [PMID: 4214945 PMCID: PMC355659 DOI: 10.1128/jvi.14.6.1337-1342.1974] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The virulent phage phie of Bacillus subtilis which contains hydroxymethyluracil in its DNA requires host DNA polymerase III for its DNA replication. DNA polymerase III(ts) mutant cells infected with phie at restrictive temperatures do not support phage DNA synthesis. However, phie grows normally both at low and high temperatures in the mutant's parent strain and in spontaneous DNA polymerase III(+) revertants isolated from the mutant strain. Temperature-shift-down experiments with phie-infected cells having thermosensitive DNA polymerase III (pol III(ts)) indicate that at 48 C the thermolabile DNA polymerase III is irreversibly inactivated and has to be synthesized de novo after the shift to 37 C, before phage DNA synthesis can begin. Temperature-shift-up experiments with phie-infected mutant cells show that phage replication is arrested immediately after the temperature shift and indicate that phie requires DNA polymerase III throughout its replication stage.
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41
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42
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43
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44
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Abstract
Escherichia coli B strains that have acquired the malB region from E. coli K-12 are able to utilize maltose and to adsorb phage lambda when grown at 30 C, but when grown at 40 C they do not absorb phage lambda and are devoid of amylomaltase activity. These Mal(ts) Lam(ts) cells can be mutated or transduced to become able to grow on maltose at 40 C, but they still have no detectable amylomaltase activity nor functional lambda receptors at that temperature. This Mal(40) phenotype is governed by a gene located near or at malA. It is suggested that the temperature sensitivity of both characters results from a defect in malT. However, transduction of malA from E. coli B to E. coli K-12 results in a wild-type phenotype, whereas E. coli B cells that have acquired malA from E. coli K-12 donors are still temperature sensitive for both amylomaltase and lambda-receptor production.
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45
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Ronen A, Atidia J. Repair of alkylation-induced damage in Escherichia coli and its bacteriophage lambda. Mutat Res 1971; 11:175-9. [PMID: 4932246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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46
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Naggan L, Gunders AE, Dizian R, Dannon Y, Shibolet S, Ronen A, Schneeweiss R, Michaeli D. Ecology and attempted control of cutaneous leishmaniasis around Jericho, in the Jordan Valley. J Infect Dis 1970; 121:427-32. [PMID: 5462404 DOI: 10.1093/infdis/121.4.427] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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47
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Abstract
Immediate and delayed inactivation of ethylmethane sulfonate (EMS)-treated lambda phage were studied. Phage particles with one alkylated and one intact deoxyribonucleic acid (DNA) strand were obtained by allowing host-modified, EMS-treated phage to undergo one growth cycle in a nonmodifying host and selecting the progeny with semiconserved parental DNA on a restricting host. The results indicate that particles with one alkylated DNA strand are more sensitive to a second treatment with the alkylating agent. When incubated at 37 C, they are subject to inactivation at a rate which is smaller than that of phages containing two alkylated DNA strands. It appears that depurination events in one of the DNA strands of a phage particle are sufficient to cause death.
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48
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Abstract
Cultures of Escherichia coli K-12 malA(-)lambda(r)gal(-) can be transduced to gal(+) by bacteriophage lambdadg because of leakiness of the lambda(r) phenotype. The efficiency of such transduction is about 10(-5) that of transduction of mal(+)lambda(s) bacteria. Leaky cells (lambda(s)phenocopies) adsorb only very few phage particles, and many transductants, therefore, are defective heterogenotes or show integration of the gal(+) gene, which is unaccompanied by lysogenization.
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49
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50
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