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ARR Honorary Members

1982 T Alper
J H Baxendale
J W Boag
M Ebert
A Howard
1984 F S Dainton
P J Lindop
J F Loutit
1990 G Scholes
O C A Scott
A Breccia
J Broerse
1993 G E Adams
N E Gillies
1996 J R K Savage
A Tallentire

1998 G G Steel

2002 E M Fielden
2004 D T Goodhead
B D Michael
2005 P Wardman

2006 J F Ward
2007 J Fowler

2008 P Bryant
2010 D Lloyd 2011 E Wright
R Cox
2014 D Henshaw 2015 J Martin Brown
2016 P O'Neill 2017 J Hendry
Jolyon Hendry: Honorary Member 2017
Jolyon Hendry was an ARR Committee member (1980-82), Secretary (1982-86), and Chairman (1990-92). He started his scientific career with a BSc in Physics from St Andrews University in 1966, then an MSc in Radiation Biology at London University with Jack Fowler as project supervisor in 1968, an external London PhD in 1971 based in Manchester with Alma Howard as supervisor, and a DSc from London University in 1991. He was a postdoctoral scientist at the Glasgow Institute of Radiotherapeutics (1971-72) and then at the Paterson Institute for Cancer Research, Christie Hospital, Manchester, being Head of Radiobiology from 1976 and later Experimental Radiation Oncology until 2002. He researched and published extensively with Chris Potten, Brian Lord and others on the radiation response of stem cell systems, and later the mathematical modelling of clinical data with Steve Roberts and radiotherapist Nick Slevin. During this period he held/co-held 20 research grants, and he supervised/co-supervised 16 PhD students. He was Associate Editor of the International Journal of Radiation Biology for 5 years and then Chief Editor (1988-95). He co-authored Fractionation in Radiotherapy with Howard Thames in 1987, and edited/co-edited 7 other books. From 2002 he spent 5 years at the IAEA in Vienna first as staff member and then Head of the Applied Radiobiology and Radiotherapy Section in Human Health. After returning to the UK he set up and was first Director in 2009 of the annual MSc course in Radiation Biology at the Gray Institute, Churchill Hospital, Oxford.
As well as his ARR positions, he was Secretary of the BIR Radiobiology Committee (1977-81), Chairman of the LH Gray Memorial Trust (1985-91), Secretary of Committee 1 of the ICRP (2005-12), and a member of: BIR Council (1980-83), MRC Committee on the Effects of Ionizing Radiation (1983-87), Examining Board for the First Examination for the Fellowship (Radiotherapy and Oncology) Royal College of Radiologists (1985-92), Standing panel of experts in Radiation Biology London University (1987-2002), Gray Laboratory CRC Committee (1988-92), COMARE (1989-97), ESTRO Radiobiology Committee (1990-99) and Council (1995-97), CRC Grants Committee (1993-2001), British Oncological Association (1994-98), Scientific Council of the Human Health Protection & Dosimetry Dept IPSN France (1995-98), WHO Expert Advisory Panel on Radiation (2000-04), Royal Society working party on Depleted Uranium (2000-02), Scientific Committee of the International Organisation for Medical Physics (2007-09), Department of Health Advisory Group on Cardiovascular Risks of Ionising Radiation (2008-10) and Human Radiosensitivity (2010-13), and Scientific Advisory Committee of the Euratom FP7 project ‘Risk, Stem cells and tissue kinetics, Ionising Radiation’ (2013-17).
He is Honorary Professor, Institute of Radiation Medicine, Chinese Academy of Medical Sciences, Tianjin, China (since 1990) and the University of Manchester (since 1995). He was awarded the Roentgen Prize from the BIR (1982), the Weiss Medal from the ARR (1997), and the Bacq and Alexander Award from the European Radiation Research Society (2010).
Professor Peter O'Neill: Honorary Member 2016
Professor O'NeillPeter O’Neill has been a Member of the Association for Radiation Research since 1978, serving as Hon. Treasure (1986-90), Vice-Chairman (1994-96) and Chairman (1996-98). The Association honoured him with the award of the Weiss Medal in 2010, and Honorary Membership in 2016. Other honours include the award of the Failla Award and Lecture in 2014 from the Radiation Research Society. He has been involved in other Societies as Chemistry councillor (1998-01) and President of the Radiation Research Society (2010-11), as secretary Treasurer (1993-95) of LH Gray Trust and as treasurer (1989-95) and chairman (2005-09) of the Miller Trust for Radiation Chemistry. He was awarded his BSc (Leeds, UK) in Chemistry (1970), PhD, under the supervision of Dr Salmon and Lord Dainton (1974) and a D.Sc (1996) in recognition of his contributions to 'Free Radical Processes in Chemistry, Biochemistry and Biology’. His formative years also involved post-doctoral periods at the Max Planck Institute in Mulheim, Germany (1974-77) and the Institute of Cancer Research, London (1977-1983). He was Head of the DNA Damage Group and is Deputy Director of the Oxford Institute of Radiation Oncology at the University of Oxford following his move in 2007 from the MRC Radiation and Genome Stability Unit, Harwell (1983-2007), where he held several senior positions. Peter O’Neill is also a Fellow of the Royal Society of Chemistry. More recently his major research interests have focussed on understanding the challenges that radiation-induced clustered DNA damage sites present to the repair pathways and as a consequence contribute to carcinogenesis at environmental radiation levels or to the killing of tumour cells. His research has resulted in about 235 peer reviewed papers. . He is a senior Editor of Radiation Research and the International Journal of Radiation Biology. In recent years he has served on numerous committees Radiation studies Section of NIH, CRUK projects committee, grants committee for US DoE, LSF facility Access committee for STFC, chair for NASA grants committee, EU committee on Emerging and Newly Identified Health Risks, and scientific advisory board for EU funded MELODI programme.
Dr J Martin Brown: Honorary Member 2015

Dr Martin Brown

Dr. J. Martin Brown is a professor in the Division of Radiation and Cancer Biology at Stanford University School of Medicine. He received his undergraduate degree in Physics from Birmingham University and his D.Phil from Oxford University in 1968. He has been member of the ARR since 1967. His research focuses on the mechanisms responsible for the resistance of solid tumors to various cancer therapies and the development of new drugs to improve the success rate of radiation therapy and cancer chemotherapy. He is well known for developing the hypoxic cell radiosensitizer etanidazole, and the hypoxic cell cytotoxin (tirapazamine), both of which have undergone phase III clinical testing. His current work is on the effect of bone marrow derived cells on tumor response, particularly monocytes/macrophages and has shown that tumor irradiation produces a influx of tumor associated macrophages, which promote tumor recurrence. In particular he has demonstrated that this influx can be inhibited and this enhances tumor response to radiation. This new strategy is being tested clinically with glioblastoma.
He has published more than 300 peer reviewed papers and has received a number of awards in recognition of his work, including the 1999 Bruce Cain Memorial Award from the American Association for Cancer Research for outstanding preclinical research in cancer chemotherapy, the 1999 Gold Medal from the American Society for Therapeutic Radiology and Oncology, the Weiss medal from the Association for Radiation Research in 2001, and the Henry S. Kaplan Distinguished Scientist Award, from the International Association of Radiation Research, in 2007. He is currently an associate editor of Anticancer Research, Radiotherapy & Oncology, Neoplasia, Cancer Letters, and Molecular Cancer Therapeutics.

Prof. Denis Henshaw: Honorary Member 2014

Professor Denis Henshaw

BSc(Lond), PhD(Nott), Senior Research Fellow in Chemistry, Emeritus Professor, University of Bristol

Denis Henshaw gained his B.Sc. in Physics from London, Westfield College and his Ph.D. in Astrophysics from Nottingham. He joined the Physics Department at Bristol as a post-doc in 1973. In 1978, the plastic CR‑39 was found to record tracks of alpha-particles. Working with teacher Dr Geoff Camplin, Denis devised a DIY radon detector using CR-39 housed in a yogurt pot with which primary-school children identified high domestic radon levels. In 1991, school children carried out the first national survey of radon in UK domestic water supplies.
Denis used CR-39 to produce alpha-particle autoradiographs of autopsy tissues and mapped the microdistribution of retained alpha-emitters in the lung. Over a 24-year period with MRC Programme Grant support, Denis led a team investigating alpha-radioactivity in the body, especially the skeleton, including transplacental transfer to the foetus. Alpha-particle levels in orthodontic teeth showed independent correlations with traffic pollution and domestic radon levels. In 1990 Denis revealed a correlation between leukaemia and other childhood cancers with domestic radon exposure, supported by radon-derived alpha-dose calculations to bone marrow. This unexpected feature of alpha-emitters was paralleled by studies of the bystander effect and genomic instability, an exciting time for radiobiology.  
Denis was appointed Professor of Human Radiation Effects in 1995. His research included field projects within the Chernobyl zone. He co-developed novel techniques for measuring radon and established Track Analysis Systems Ltd, TASL, a company that won the Queen’s Award for Innovation in 2013.
Since 1996, Denis has been interested in the health effects of electric and magnetic fields. Electric field gradients on high voltage powerline cables can ionise the air, emitting corona ions into the atmosphere. These progressively attach to particles of air pollution, increasing their charge state causing them to have a greater probability of lung deposition if inhaled. Denis’s team’s extensive research at Bristol into powerline corona ion emission may explain the reported increased incidence of leukaemia in adults and children, at substantial distances from power lines. Additionally, magnetic fields have been related to increased cancer incidence and Denis has studied the underlying mechanisms.
Denis retired in July 2011, acting since as Scientific Director of Children with Cancer UK, which funds research into the causes, prevention and treatment of childhood cancer. He is also an Associate Editor of IJRB.

Prof. Eric Wright: Honorary Member 2011 
Photo of Dr Peter Bryant Eric Wright is a graduate of the University of Sussex and obtained his PhD from the Faculty of Medicine in the University of Manchester having undertaken his research at the Paterson Institute. After research fellowships in the Sloan Kettering Cancer Center in New York and the Paterson Institute, in 1980 he was appointed Lecturer in Cellular Pathology at the University of St Andrews. In 1987 he moved to the Medical Research Council’s Radiobiology Unit at Harwell (subsequently re-titled the Radiation and Genome Stability Unit) where he held senior posts until 1999 when he moved to the Chair of Experimental Haematology in The University of Dundee. From 20003-2008 he was Head of the Cancer Biology and Clinical Pathology Unit and from 2003-2010 Medical School Research Dean. Prof Wright is a Fellow of the Royal College of Pathologists with a long-standing interest in the regulation of the haemopoietic system, the cellular and molecular responses to radiation injury and mechanisms underlying abnormalities of stem cell function such as bone marrow failure and leukaemia development. In 2007 he was elected a Fellow the Royal Society of Edinburgh having been awarded their The David Anderson-Berry Medal in 2004. In 2007 he was awarded the Weiss Medal of the Association for Radiation Research, the Bacq Alexander Award of the European Radiation Research Society and was elected a Fellow of the British Institute of Radiology. In 2009 he was awarded the Silvanus Thompson Medal of the BIR.  In recent years he has served on numerous committees including the Committees on Medical Effects of Radiation in the Environment (COMARE) and Radiation Risks of Internal Emitters (CERRIE), the US Low Dose Radiation Research Program and NASA’s Specialized Centers of Research Committee. He has been an Associate Editor of Radiation Research, a Subject Editor of the British Journal of Cancer and a member of the Editorial Board of Hematological Oncology. He has also been a specialist examiner for the Royal College of Radiologists Faculty of Clinical Oncology, a member of the Steering Committee of the UK Academic Clinical Oncology and Radiobiology Research Network and Chair of the Radiation and Cancer Biology Committee of The BIR, the Trustees of the LH Gray Memorial Trust, the Association for Radiation Research and the Scientific Advisory Committee of The Association for International Cancer Research.

Prof. Roger Cox: Honorary Member 2011 
Photo of Dr Peter BryantRoger Cox was born in Swansea and attended schools in the Cardiff area.  He subsequently received a first degree in Microbiology and a PhD in Microbial Genetics from Reading University.  From 1971 to 1990 he undertook research at the MRC Radiobiology Unit (Harwell) centred on the cellular/molecular mechanisms of DNA damage response.  In 1990 he was appointed Head of Biomedical Effects at the National Radiological Protection Board (NRPB Chilton) where he was involved in a broad range of research programmes on ionising/non-ionising radiation effects but with a major focus on the mechanisms and genetics of tumour induction.  He became Director of NRPB in 2003 and, following a multi-agency merger, in 2005 he became Director of the Health Protection Agency (HPA) Centre for Radiation, Chemical and Environmental Hazards (Chilton HQ). Roger Cox also fulfilled senior scientific/managerial roles within HPA for emergency response and was closely involved in public health aspects of the London Bombings, the Buncefield Fire, the Polonium Incident in London and the Swine Flu outbreak. In addition to his duties with UK Government/Agencies Roger Cox has worked closely with international bodies with responsibilities in radiological protection, in particular: the International Commission on Radiological Protection (1989-date, Vice Chairman 2005-2009), the United Nations Scientific Committee on the Effects of Atomic Radiation (1989-2009, Head of UK Delegation 2003-2009), the European Commission (expert advisor and research co-ordinator), and the US National Academy of Sciences (Foreign Associate within BEIR V11 Committee 1999-2006). Roger Cox is a Fellow of the UK Academy of Medical Sciences, a Fellow of the Society for Radiological Protection, a member of the Board of the Gray Cancer Institute and holds an Honorary Professorship at Brunel University.  He retired from his HPA position in 2009.

Dr David Lloyd: Honorary Member 2010
Photo of Dr Peter BryantDavid Lloyd has been a member of the Association since 1971 and twice served on the Committee.  Born in London, he studied zoology in the University of Wales successively in Swansea, Bangor and Cardiff as undergrad, post-grad and post-doc. He was then recruited by Andrew McLean and Geoff Dolphin to join the National Radiological Protection Board at its inception in 1971. His subsequent career has been spent in radiological protection until his retirement in 2008. Throughout that time in NRPB and latterly, the Health Protection Agency which absorbed NRPB in 2005, his main interest has been the development and application of chromosomal aberration analysis as a biological dosemeter for investigating radiation accidents. He has steered the evolution of this field from a promising research idea into a routine component of the radiological protection programmes of many countries. From this very practical application arose a large body of dose response data, particularly at low doses, which has additionally provided an ideal endpoint for testing many of the more fundamental concepts in radiobiology such as the dose rate effect, the RBE/LET relationship and so on. A significant point in his career was the 1986 Chernobyl accident, followed soon after by the break-up of the Soviet Union. These paved the way for him to develop highly productive and enduring associations with a number of eastern laboratories. Latterly, with the heightened concerns for international terrorism, his work has turned to how the biological dosimetry community world-wide can mount a concerted and effectively response to mass casualty events involving radiation. In ‘retirement’ he maintains an active emeritus position with HPA and is also working with United Nations agencies, IAEA and WHO, in developing and optimising their rapid response preparedness.
Dr Peter Bryant: Honorary Member 2008
Photo of Dr Peter BryantDr Peter Bryant has been a Member of the Association since 1965, serving on the committee, and as Vice-Chairman 1992-94, Chairman 1994-96, and he also represented the ARR on the International Association of Radiation Research Committee. With Peter Wardman and Jolyon Hendry he helped edit the International Journal of Radiation Biology while it was still based in Manchester. Born in Sutton Coldfield, Peter was educated at Luton Grammar School and at Exeter University. He trained as an (MSc) radiation biophysicist at the University of London's Royal Free Hospital under Norman Kember, and then at the Royal Postgraduate Medical School at Hammersmith Hospital. He was appointed to the scientific staff at the MRC Experimental Radiation Research Unit, Hammersmith Hospital and worked with Shirley Hornsey and Bill Cramp, under the Director (and his PhD supervisor) Dr Tikvah Alper. He was awarded a PhD in 1970 for his work using the micro-alga Chlamydomonas to study the biological response to LET (especially in relation to the 'oxygen-in-the-track' hypothesis to account for the decrease in OER at high LET, and also on the striking 'adaptive response' in this organism). Following completion of his PhD he worked as a post-doc in 1970 on the radiation response and DNA of the cellular slime-mould D.discoideum at the Life Sciences Department, Penn State University under Reg Deering. He was awarded a DSc in 1994 by the University of London. He continued working for the MRC ERRU at Hammersmith Hospital until 1978 after which he moved to Germany, working with a team of scientists at the GSF Biophysics group in Frankfurt (am Main) including Dieter Frankenberg, Marlis Frankenberg-Schwager and Georg Iliakis until 1985 when he was appointed as a lecturer at St Andrews University, Scotland to run a post-graduate course in Radiation Biophysics with Andrew Riches and colleagues from Dundee University. The research in his groups both at Frankfurt and St Andrews was focused on DNA double-strand breaks in mammalian cells, and especially on how they are converted into visible chromosomal aberrations. Most of his recent research is aimed at understanding the molecular mechanisms underlying radiation-induced chromatid breakage and its relationship to breast cancer susceptibility. He is currently continuing research as a Research Reader at the Bute Medical School, University of St Andrews.

Prof. John F Fowler: Honorary Member 2007
Photo of Jack FowlerJohn F (Jack) Fowler graduated from Exeter University College and spent several years in hospital physics in Newcastle (with Frank Farmer) and London, before joining the MRC Radiotherapeutic Research Unit at Hammersmith Hospital in 1959. In 1962 he became Reader in Physics in St Bartholomew's Hospital Medical School, and a year later returned to Hammersmith as Professor of Medical Physics. In 1970 he was appointed Director of the British Empire Cancer Campaign's Research Unit in Radiobiology at Mount Vernon Hospital, which he greatly expanded and renamed the Gray Laboratory. Under his leadership the 'Gray Lab' flourished, nurturing future leaders including Ged Adams and Julie Denekamp. Jack led from the front, responding to enthusiasm with enthusiasm. Interactions with clinicians including Stanley Dische and Michele Saunders established productive working relationships between the lab and the clinic long before the term 'translational' was coined. On retiring as Director of the Gray Lab in 1988 (some 'retirement'!), Jack moved to the Departments of Human Oncology and Medical Physics at the University of Wisconsin in Madison, serving as Visiting Professor and on Faculty. He became Emeritus Professor in 1994 and returned to London, during his second 'retirement' serving as Visiting Professor to the University of Leuven, Belgium (1995-1999), and also as Visiting Scientist and Research Adviser to the University of Umeň, Sweden. In 1999, Jack re-visited Madison where he worked as a very active Emeritus Professor until 2004. He has made numerous contributions to experimental and clinical radiation biology, especially to fractionation in radiotherapy and the application of the linear quadratic model to clinically-relevant problems, teaching a whole generation of clinicians and physicists and producing several definitive reviews on this topic. During his Madison years he worked mainly on clinical radiation biology and he was instrumental in developing several clinical trials, some still in progress. Jack has received numerous honours, including a remarkable 'triple' as recipient of the Gold Medals of ESTRO (1983), ASTRO (1995) and the Failla Award Lecture of the Radiation Research Society (2002), the highest honour bestowed on an individual by these three societies.

Prof. John Ward: Honorary Member 2006
Photo of Professor John Ward  

John Fawcett Ward was born (1935) in Blyth, Northumberland. He obtained his B.Sc. from King’s College, University of Durham in 1956. There followed his Ph.D. (Action of Radiation Produced Radicals on Nucleic Acids and Related Compounds) in 1959 with George Scholes and Joseph J. Weiss from the same institution. He remained at Newcastle working with visiting scientist Shigefumi Okada until 1962 when he moved to UCLA to take up a postdoctoral position with Larry Myers. Within a year he was given a more permanent position. He moved again in 1978 to UCSD as Professor of Radiology where he remained until his retirement in 2001.
He has been fortunate in his many collaborations with e.g., Hazel Lewis, Ivar Johansen, John Byfield, John Zimbrick, Jürgen Hüttermann, John Murnane, Les Redpath, Tony Leadon, Bill Blakely, Jamie (Spike) Milligan, Don Jones, Charlie Limoli, David Brenner, Bob Fahey, Bill Dewey and Gerhard Kminek.
His research focused on molecular mechanisms of biologically important radiation damage. He developed the concept of locally multiply damaged sites (sometimes called clustered damage) and the difficulties of repair of such.  He showed that these LMDS distinguished radiation damage from oxidative damage.  Mechanisms of action of radiosensitizers (halouracils) and radioprotectors (thiols) were other areas of study. In toto this work resulted in ~150 publications.
Funding for the research was mainly from the NIH, with occasional support from the capricious DOE.
His career has been mainly in the U.S. thus his ‘home’ society has been Radiation Research. He has had a variety of appointments in that Society; Councilor for Chemistry, Editor, President and Editor-in-Chief of the journal Radiation Research. In 1991 he was Vice- President of the IXth International Congress of Radiation Research.
His awards include the Weiss Medal from the Association for Radiation Research, 1995 and the Failla Award from the Radiation Research Society, 1997.

He has reviewed manuscripts and grants for many journals and agencies; he served two stints on the NIH Radiation Study Section, the latter time as Chairman.

Prof. Peter Wardman: Honorary Member 2005
Photo of Prof Peter WardmanPeter Wardman has been a Member of the Association for Radiation Research since 1973, serving as Honorary Secretary (1978-82), Vice-Chairman (1990-92), Chairman (1992-94), and Honorary Treasurer of the 8th International Congress of Radiation Research, hosted by the Association, in 1987. He has also served as Councilor for Chemistry in the International Association of Radiation Research and the [US] Radiation Research Society. The Association honoured him with the award of the Weiss Medal in 1987, and Honorary Membership in 2005. Other honours include the award of the Silvanus Thompson Medal of the British Institute of Radiology (2008), and the Maria Sklodowska-Curie Medal of the Polish Radiation Research Society (2013). He trained as a radiation chemist at the University of Leeds under the direction of Lord Dainton FRS (receiving the H M Dawson Prize for Physical Chemistry in 1964), and was awarded the degrees of PhD in 1967 and DSc in 1990. Postdoctoral appointments included work at Chalk River Nuclear Laboratories, Ontario, and with John Baxendale in Manchester, followed by a short period working on environmental chemistry problems with the British Aircraft Corporation. Ged Adams recruited him to the Gray Laboratory in 1973, introducing him to broader applications of radiation chemistry, notably the rational development of hypoxic cell radiosensitizers, and hypoxia-selective drugs and diagnostic probes. Research work, published in about 250 articles, has included many studies of the redox properties of free radicals, marked by a review in the Journal of Physical and Chemical Reference Data in 1989 which has received about 1000 citations; more recent interests include the chemistry of free-radical associated oxidative and nitrosative stress. He has been associated as visiting professor with Brunel University, King's College London, University College London, and the University of Oxford. Before his retirement, he was head of the Cancer Research UK Free Radicals Research Group, and Deputy Director of the former Gray Cancer Institute at Mount Vernon Hospital, which is now part of the Department of Radiation Oncology and Biology of the University of Oxford, having relocated to Oxford in 2008.

Dr Martin Fielden: Honorary Member 2002
Photo of Dr Martin FieldenDr Martin Fielden has been a Chairman (1988-90), Treasurer (1974-78) and long standing Member of the Association. Both he and his wife attended the ARR2003 Conference Dinner at St. Catherines College, Oxford, where he was presented with the Honorary Membership by Prof. Eric Wright. Dr Fielden is well known to both radiation chemists and radiobiologists alike in applying his chemical skills to radiobiological questions. Martin started his research career as a radiation chemist when pulse radiolysis was in its infancy. On taking up a position at the Institute of Cancer Research and subsequently at the MRC's Radiobiology Unit, Harwell, Martin's research interests focussed more on biological aspects of radiation research involving pioneering approaches to study mechanisms of radiation-induced DNA damage in E. coli and later in mammalian cells, when he developed his interests in stable nitroxyl free radicals as radiosensitisers. He was involved in seminal studies on unravelling the mechanisms by which Superoxide Dismutase interacts with its substrate superoxide, a novel role in protection against reactive oxygen species. He has made many significant contributions to the field of radiation research both as a researcher and a mentor. Martin's achievements were recognised by his peers with the award of the prestigious Radiation Research Society Research Award (latterly know as the Michael Fry Research award) and the David-Anderson-Berry Gold medal by the Royal Society of Edinburgh. Martin has been actively involved over the years with the ARR as treasurer and chairman and more recently as the secretary-general of the International Association for Radiation Research'.

John R K Savage: Honorary Member 1996

With a 1st class honours B.Sc. and a Ph.D. in plant cytogenetics, I joined (1956) the biophysics group at the MRC Radiobiological Research Unit to work on radiation-induced chromosomal aberrations, a topic which was to dominate my 40+ year career. At the time, experimental work in this field was only possible with plant chromosomes, and already a sound foundation for basic qualitative and quantitative radiobiology had been established with such materials (c.f. Lea’s classic 1946 textbook : “Actions of radiations on living cells”.)
The Unit was situated on the AERE campus, and this gave us access to many different kinds of radiation, of which we made good use.
The time I joined was at the start of a major controversy, the first serious challenge to the universally accepted ideas of the nature of observed aberrations, the “breakage first then reunion” theory. Revell was proposing essentially “exchange first, and all observed breaks were actually failed intrachanges”. (discussion : Mutation Research, 404: 139-147 (1998).). The resulting arguments were intense and polarising, and they sparked, for us, a lot of experimental and theoretical work. In retrospect, progress was hampered by our very simplistic views of chromosome structure, ignorance of the key role of the DNA molecule for chromosome integrity, and the severe limitations of solid staining and light microscope resolution.
In 1962, I had a spell lecturing a post-graduate radiobiology course at Cornell University, USA, which gave me the opportunity to meet several important American aberration scientists.
The introduction of isotopic methods for analysing the cell cycle, allowed us to begin to relate aberration formation to the cell developmental phases. This was now facilitated by the ability to use mammalian, and human cells in culture. However, understanding of the real impact of cell kinetics on aberration scoring was yet to come.
I got involved in another important controversy whilst working with Tradescantia. Anomalies in inter-cell distributions of chromosome-type exchanges, together with warping of dose response curves, led to the suggestion that there were actually very few places within the interphase nucleus (termed “sites”) where exchanges could take place. This had important implications for theories of aberration origins. I conducted a lot of experiments and undertook much theoretical and mathematical thought. I was able to show that the observations were actually an artefact, resulting from the use of solid staining, since this technique does not allow one to identify chromosomes involved in more than one chromosome-type exchange (“distortion hypothesis” Current Topics in Radiation Research 6: 130-194 (1970)). This realisation also offered the solution to the puzzle as to why complex exchanges were so rare for chromosome-type exchanges when so common for chromatid-types. Resulting from these studies I was awarded a D.Sc, from the University of Southampton in 1970. The frequency and importance of complex exchanges would be realised later when the chromosome “painting” technique arrived.
With animal cells came the technique of chromosome “banding”, giving ability to identify individual chromosomes, locate more accurately exchange positions, and in many cases to define aberration types more certainly. Many additional experiments now became possible. My aberration expertise together with my banding studies brought me into active contact with clinical cytogenetics, and I lectured and published extensively for the Association of Clinical Cytogeneticists (ACC) training courses, and also did some collaborative experiments. My contributions were acknowledged by my election, in 1995, to “Emeritus Fellow of the ACC”.
The quantification of aberration frequencies and the construction of dose-response curves has always played a very important part in theoretical aberrations studies. Any observed aberration frequency depends upon the mixture of cell present in the metaphase scoring sample. Individual cells transit their phases and converge towards the scoring sample at very different speeds, so they come from a range of cycle positions at the time of radiation. The mix of cell positions present will obviously change with post radiation sampling time, and the observed aberration frequencies are not directly comparable. This problem is exacerbated by the fact that transit rates are subject to dose-dependent perturbation (mitotic delay). Thus, it is much more difficult to obtain a meaningful quantitative score and dose-response curve than most people realise. I have spent a lot of time on this problem, (“imprecision”, Advances in Mutagenesis Research, 3: 162-189. (1991), ( ed. G. Obe)). Some cell unscrambling to get more homogeneous scoring samples can be obtained by using BrdU replication band patterns for individual S-phase cells, (Journal of Medical Genetics 31: 204-212 (1984)) but for other phases there is currently no solution. The problem of imprecision is particularly acute for chromatid-type aberrations because of the profound changes in chromosome packing during S/G2 transit towards mitosis, (Journal of Theoretical Biology 38: 17-38 (1973).).
The advent of chromosome painting (“FISH”) confirmed, beyond doubt, that the formation of chromosomal aberrations is much more complex than we have hitherto realised. Lots of aberrations which, with solid staining, we have classified as simple, two-chromosome events, actually involve the interaction of three, or more, chromosomes ! (Mutation Research,512: 93-109. (2002)).
So, our established classifications (e.g. Journal of Medical Genetics, 13: 103-122. (1976)) now need considerable revision for critical studies. This led me to introduce the CAB system for simple classification, and there have been suggested scoring systems like “PAINT” and S&S (Mutation Research, 366: 153-161. (1996)).
In 1995, the third international symposium on “Radiation Induced Chromosome Aberrations”, took place in Essen, and was held in my honour, (Mutation Research 366: 1996 (special issue, eds. A T Natarajan & G Obe)), in recognition of my contributions to this topic. I was elected to Honorary membership of the ARR in 1996, and in 2005, my research work and publications (>200) in aberration cytogenetics was honoured by the European Society for Radiation Biology with the award of the Bacq and Alexander medal.
It is gratifying to feel that ones research has been a help and stimulus to others.