22 October 2014
A hitch-hiker’s guide to the blood system
Dr Ceri Marrin
Dr Ceri Marrin, Consultant Haematologist at Cardiff University Hospital, started her talk with a whistle-stop tour of the blood system, and on the role of a haematologist in the NHS. What appealed to her was the way she was able to combine her clinical duties with an interest in research and the development of new treatments. She described the importance of blood, and its main constituents, and the role they each played in the body. Red cells (erythrocytes) contain haemoglobin, which binds to oxygen, which the circulation of the blood delivers to all the cells in the body. The blood also transports carbon dioxide away from cells. The white cells (lymphocytes and leucocytes) play a vital part in the body’s defences against bacteria and viruses and producing antibodies. Platelets are responsible for the clotting process that stops bleeding and repairs tissues after injury. The cells are transported in a liquid called plasma, which also contains other proteins necessary for cellular function.
With such a complex system things can go wrong. Ceri described the measurements that can be performed on blood in the laboratory, and how they can be interpreted. She gave examples of normal and abnormal blood, illustrated with slides taken through a microscope.
Ceri described the system of blood typing, explaining the ABO system which is most commonly used. She emphasised the importance of blood donation, and how the demand for blood will increase in the future. She described the circumstances in which blood transfusion may be necessary, and the risks involved.
Ceri’s main clinical interest is in malignant haematology, in particular in myeloma, a disease of the bone marrow. Myeloma represents about 1.5% of all cancers, with about 5000 new cases each year. It is incurable, but great strides have been made in recent years in its management and treatment. Its diagnosis is difficult, particularly in the early stage when it can mimic other diseases. In the last 10 years new drugs have become available, and younger/fitter patients maybe offered autologous stem cell transplantation. Five-year survival is now greater than 50%. Recent research interests include monoclonal antibodies to target cell surface markers, and proteose inhibitors. Ceri touched on the problems of health economics, with the cost of novel treatment being very high, with a growing population with more elderly patients.
The evening closed with a wide-ranging session of questions in which Ceri’s knowledge and expertise was well demonstrated.
Report by Bob Barber
24 September 2014
ALFRED RUSSEL WALLACE – a life explored
David Croman gave us a good introduction to Alfred Russel Wallace, the man and his work. Wallace formulated a theory of evolution by means of natural selection, completely independently of Charles Darwin. However, family problems and various setbacks concerning his collection of specimens to back-up his ideas, meant that Darwin’s own work had a greater impact on the eventual acceptance of the theory.
David started by giving us a potted sketch of Wallace’s early life. He was the eighth of nine children, and he left school at fourteen. At first he set up a surveying business with his brother, but it was his friend and colleague, Henry Walter Bates, who introduced him to natural history. In 1848 Bates, with Wallace, left for Brazil to collect specimens in the Amazon rainforest. Unfortunately, a large part of his collection got lost on his return to England in 1852 when the ship on which he was travelling caught fire.
From 1854 to 1862 he travelled through the Malayan Archipelago to collect specimens and study the natural history there. These studies led him to arrive independently at the theory of evolution, now mainly attributed to Charles Darwin. Darwin at this time had not published his theory, but when Wallace sent him a memoir of his ideas, asking him to forward it for publication, Charles Lyell and Joseph Hooker advised Darwin that he should publish his own thoughts at the same time. On the 1 July 1858 both men had their papers presented at the Linnean Society of London.
David made it clear that Wallace in no way envied the adulation given to Charles Darwin, since Darwin had a far greater body of evidence to support his ideas. Wallace noted a line seem to run through the Malay Archipelago between Borneo and Celebes and east of Bali. This line, which is now known as Wallace’s line, separates the continents of Asia and Australia zoologically. West of the line, most species found were related to Asiatic species, to the east most species are related to Australian species.
At the end of the meeting there was a lively discussion from the floor, which showed that many people were not really aware that Darwin was not the sole proposer of the theory of evolution. David gave us a well-rounded picture of the man and his work and his impact on the theory which stands at the heart of the biological sciences.
Report by Percy Seymour
Exploring the atmospheres of alien worlds
23 July 2014
Hannah Wakeford, a research student from Exeter University, gave us a very good talk on her work analysing the chemical composition of the atmospheres of exoplanets, the planets circling other stars in our Galaxy.
She introduced the way we built up our knowledge of our own Solar System. She told us about how Uranus was the first planet to be discovered with a telescope, and how irregularities in the orbit of Uranus led to the theory that there was another planet which was gravitationally pulling Uranus out of its orbit. The orbit of this, as yet telescopically undiscovered planet, was calculated by two mathematical astronomers, John Couch Adams in England and Urbain Levier in France, and the new planet, subsequently called Neptune, was discovered by Galle, a German astronomer, working at the Berlin Observatory.
Hannah then described the main methods used for detecting planets around other stars. The first method was to search for the regular movements of a star which could be caused by a large planet orbiting it. The next method, called the transit method, made use of the fact that an orbiting planet moving between an observer on the Earth and its parent star would blot out some of the light coming from the star. This method could be used to calculate the radius of the planet, but by studying the way the light from the star was absorbed by the planet’s atmosphere we could also work out the chemical composition of the atmosphere. This was the main method used by Hannah in her research work. The third method was to study how the spectral lines of the parent star were shifted by the Doppler Effect, as the orbiting planet caused the star to move towards and away from the observer.
Over 2000 exoplanets have now been discovered, and Hannah described the characteristics of the main types. (see Wikipedia for more details:http://en.wikipedia.org/wiki/Extrasolar_planet )
Hannah’s work was mainly concerned with detecting water in the atmospheres of these alien worlds. She ended her talk by considering the factors necessary for a exoplanet to have liquid water, and raising the possibility of intelligent life forms. Among the necessary requirements which she listed were the following: The planet had to be a certain distance from the star, so that it would not be too hot or too cold. Second it had to have the right mass and size so that it could gravitationally retain an atmosphere with life friendly conditions. Thirdly, it had to be a rocky planet with a stable surface, and not a gaseous giant.
Once again, the evening ended with many questions and a lively discussion.
Report by Percy Seymour
Wave-Particle Duality - and the frightening consequences Professor J Roy Sambles 25 June 2014
Modern quantum mechanics represents one of the most surprising and intriguing aspects of twentieth century physics. Perhaps the most puzzling is the wave-particle duality – waves can sometimes behave as if they are particles and particles can sometimes behave like waves. Professor Roy Sambles, from the University of Exeter, introduced us to some of the more bizarre consequences of this ‘Jekyll and Hyde’ character of the subatomic world. He started by discussing, in historical terms, the work of Isaac Newton, Thomas Young and Albert Einstein on the nature of light. Newton proposed the corpuscular theory of light, Young supported the wave theory, Max Planck showed that light came in packets of energy and Einstein showed that that these packets of energy could interact with matter as if they were particles. Roy Sambles used the wave theory to explain how the colours seen in soap films arose, and went on to discuss the diffraction and interference of light. To clarify further the nature of light waves, he did some demonstrations with elastic bands, and used this to illustrate transverse waves and polarization, both linear and circular. This led him on to discuss how some special types of crystal could give rise to two images of a single object. He showed us how Young’s double slit experiment gave rise to constructive and destructive interference, thus producing an interference pattern, and how this could be used to measure the wavelength of light. He then showed that the same experiment could be done with electrons, in an electron microscope, thus confirming the wave nature of electrons. We were then introduced to an aspect of quantum theory, which Einstein called the ‘spooky action at a distance principal’ which means that two particles seem to be instantaneously connected to each other, even if they are a great distance apart. In recent years this quantum entanglement has been tested experimentally, providing yet further evidence about this weird nature of quantum mechanics. At the end of the talk there were several interesting questions and a lively discussion followed on from the questions. Report by Percy Seymour
Dr Gianluca Memoli
28 May 2014
Dr Memoli, from the National Physical Laboratory in Teddington, gave us a very interactive, amusing, entertaining and enlightening talk on the subject of bubbles, which is his particular area of expertise. Dr Memoli started his studies at the University of Pisa, which was made famous by Galileo.
He started with a brief introduction to the work of the NPL, and then moved on to bubbles. He explained that balloons, and most smaller bubbles, were spherical, because the shape of the sphere means that for a given volume it has the least surface area. In the case of the balloon it was the tension in the elastic that is minimised, and in the case of the soap bubble it was the surface tension of the soap film.
Dr Memoli discussed the fact that the tastes of various substances and drinks were affected by the bubbles in them. Chocolates with bubbles, such as Aero, tasted rather different from chocolates that had no bubbles. The bubbles in cheeses also altered their tastes. Some people believed that the bubbles in Champagne was a major contributory factor to the taste of the drink. He also discussed how the bubbles produced by yeast played an important part in the texture and density of bread. The bubbles produced by cleaners and detergents were important to the whole process of cleaning.
Bubbles could also produce sound, and the noise made when the waves of the ocean break upon the beach came largely from the bubbles in the surf. We also learnt about how bubbles were used to treat cancer. They were injected into the blood and ultrasound waves were targeted at them so that they penetrate the cell membrane and burst, releasing drugs, which destroy the cell.
During the interval some of the members of the audience tried out some of Dr Memoli’s experiments for themselves. At the end there were several questions which help to clarify parts of his lecture.
Report by Percy Seymour
23 April 2014
The Mary Rose - Preserving an old wreck with nanoscience
Prof A V Chadwick
Professor Alan Chadwick, Emeritus Professor at the University of Kent, gave an illustrated talk on some of the science behind the preservation of the wreck of the Mary Rose. The Mary Rose, flagship of the navy of Henry VIII, was built in 1509 and sank in Portsmouth Harbour in 1545 following a confrontation with the French fleet. Why she sank is unclear; the most likely reason being later modifications that made her unstable when fully loaded. Over 500 men were lost, only 36 surviving the episode. Contemporary attempts to raise her failed. The wreck was rediscovered in 1836 by Whitstable divers and re-located in 1971. The raising in 1982 was covered live on television. A large fraction of the hull and 20 000 artefacts were recovered and are under conservation. They are currently on exhibition and represent a unique insight into Tudor life.
The Mary Rose Trust has collaborated with the University of Kent to deal with the challenges of the conservation process. The experienced gained by the Swedish team working on the Vasa highlighted a particular problem with sulfur compounds which built up in wood following immersion in polluted sea water, particularly in the presence of iron. Subsequent exposure to oxygen has lead to the formation of sulfuric acid which degrades the wood. Techniques to identify the compounds were developed using the national synchrotron, the Diamond Light Source, at Didcot in Oxfordshire. This machine emits an intense beam of synchotron radiation whose energy can be selected to be in the X-ray region. K-edge X-ray absorption spectroscopy is used to identify the sulphur species present in samples from the wreck; the absorption edge occurring at a different energy depending on the compound.
The research team at the University of Kent have long experience in the development of nanoparticles, and have managed to produce particles as small as 20nm, easily small enough to enter the cells in wood. The plan is to neutralise sulphuric acid and other reactive sulphur compounds with nanoparticles of the alkaline compound strontium carbonate. At the moment the penetration into wood is limited and may only be suitable for small samples. The conservation process will continue for many years, and monitoring of the hull and artefacts will need to continue to fully understand the problem of sulfur.
Report by Bob Barber
26 March 2014
Dr Tim Harper
Fraccing - Friend or Foe?
Dr Harper introduced his presentation by reminding the audience that 10 days ago was the 65th anniversary of fraccing. The purpose of fraccing is to initiate cracks in the rock wall around the well, keeping them open and permeable, by injecting a suitable ‘proppant’. The technique was discovered by chance in the 1940s with the first commercial application in March 1949. He then showed a diagram of how the well is constructed, typically 3 km deep and 15 to 20 cm diameter, cased in sections with cement lining at the intermediate junctions. In the 1980s stimulation wells in the North Sea saw the introduction of horizontal drilling and the early application of multiple-fracced horizontal wells. They were also used in geothermal energy extraction in Cornwall. The 2000s saw the emergence of multistage hydraulic fracturing of shales – shale permeability is low hence the need to increase permeability by fraccing. A map showed how shale gas resources are very significant and widespread. Fraccing is a natural process but by 2008 it had reached the public consciousness as some environmental and media groups rebrand the previously entirely non-controversial process ‘Fracking.’
26 February 2014
Resuscitation Science – the future, facts and myths
Mr Edward Baker, Medical Research Scientist at King’s College, London with clinical duties at King’s College Hospital spoke on resuscitation science – the future facts and myths. He began his talk by discussing cardiac arrest stating that the primary symptoms were chest pain and shortness of breath resulting in a drop in blood pressure, lack of perfusion and low oxygen levels in the organs of the body. He told us there were 33,000 cases annually in the U.K. out of hospital, of which 40% received treatment and 5% survived.
Although emphasising that the talk was not intended to be a training session, Edward then moved on to advise on the action to be taken: initially a 999 call must be made. The target time for an ambulance to arrive is eight minutes; unfortunately the brain will begin to die if starved of oxygen for more than 4 minutes. Cardio-pulmonary resuscitation should be started immediately with pressure on the sternum sufficient to depress the chest by 5-6cm, at a rate of 120 per minute, with two breaths after each 30 compressions. He noted there is considerable reluctance amongst the general public to respiratory intervention, 31% being worried about catching HIV, but emphasised that cardiac intervention is better than nothing.
Edward then discussed defibrillation, noting the heart will respond if in ventricular fibrillation or tachycardia. In Sherborne there is a defibrillator near the police station and all branches of Waitrose have one. Instructions as to use are an integral part of the equipment.
After briefly reviewing the Krebs cycle he moved on to outline the effects of oxygen deprivation. Reperfusion can be followed by injury if not carried out carefully. After circulation is restored, reactive oxygen species within the mitochondrion leads to mitochondrial dysfunction with blood vessel instability, cell death and raised inter-cranial pressure.
Lastly he discussed methods of controlled reperfusion: therapeutic hypothermia and extra-corporeal membrane oxygenation (ECMO), where the body temperature is reduced to 32 degrees centigrade and cannulae inserted and connected to the ECMO circuit. Blood flow is then increased until respiratory and haemo-dynamic status is stable; re-oxygenation can then take place.
Amongst researchers there is some controversy as to the effectiveness of the procedure. He had been involved on three occasions, one of which was on a patient in her thirties who collapsed post-natally. This case was successful with only minor neurological dysfunction and the patient sent photographs of herself and her three-month old baby to the department.