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Glossary
All skilled workers accumulate their own vocabulary that is often difficult to understand for outsiders. This is particularly true of the medical profession. In the present web site whilst trying to avoid the use of specialised words as far as possible those words or phrases which are likely to cause trouble to a lay reader have been underlined in the text and a definition appears in the glossary in alphabetic order of the first word. These days anyone with access to a computer can readily find a definition by simply entering the word you are interested in into a 'search' engine such as is offered by, for example, GOOGLE. in this web site words we have chosen not to define are linked, as indicated in the Home page, to www.Answers.com .
A
An acute disease is one that is usually short and sharp. Measles is a good example. However it should be noted that although the disease of measles is acute the infection may last a very long time although there are no symptoms except resistance to further disease caused by measles virus.
This is an adjective referring to viruses or bacteria that are used for purposes of vaccination because it is known that they are less harmful than the wild-type organisms that can cause disease.
B
Tumours that do not usually kill their hosts are referred to as benign.
A sample of living tissue often taken to determine the nature of an illness is referred to as a biopsy. Sometimes the tissue is taken with a penetrating needle that has the capacity to cut out and withdraw a small piece of tissue.
C
A catheter is a hollow flexible tube that is used in medicine to sample or view parts of the body or to deliver medicaments in specific locations. The positioning of the tube after its insertion into the blood vascular system is usually by some kind of imaging device such as X-rays. Radiologist who are adept with catheters can get them to almost any part of the body quite easily and without doing harm.
In the present context a chimaera is an organism having cells derived from two different zygotes. Probably all humans are chimaeras in the sense that during our period in the womb of our mother we receive from her some cells that can persist for the rest of our lives. Equally the mother receives cells from her baby that probably persist for the rest of her life. The scale of chimaerism is not large and there are not usually any adverse consequence of being a chimaera. More well known is that transplantation is practised in humans to replace defective organs such as kidney, heart and liver and that the outcome is technically a series of chimaeras.
A chronic disease of the liver involving the replacement of normal tissue with fibrous tissue and the loss of functional liver cells. It can result from among other causes, alcohol abuse, nutritional deprivation, or infection especially by one of the hepatitis viruses.
Chronic diseases last a long time. Cancer is usually a chronic disease as is osteoarthritis. In the present context, cirrhosis of the liver is a chronic disease as usually is HepC infection.
D
Tissues and organs in the human body are continually in a state of decay and repair. Even solid seeming organs like bones are normally engaged in a cycle of loss and replacement of cells. There are even in bones cells named osteoclasts, ie the cells which break bone down and osteoblasts, the cells which build bone up. Thus the decay and repair is a perfectly normal process which proceeds in a way that is in the main imperceptible. Some tissues, like nervous tissue turn change over only very slowly, other tissues, like the lining cells of the alimentary canal, change over relatively rapidly. In all organs to various degrees there can arise, often as part of an ageing process, circumstances in which the decay and repair are not in balance or the repair process is inaccurate and does not restore what was there before. In the liver, as indicated elsewhere in this web site, when the decay and repair system goes wrong cirrhosis of the organ can result. In the brain Alzheimer's disease can develop. In the lung Chronic Obstructive Pulmonary Disease can be the outcome. All these disease conditions in various ways attract the epithet degenerative.
E
F
G
This word is an adjective commonly relating to something depending on the function of genes. Genes are discrete units that carry highly specific information which appropriately applied is what makes living things work. Perhaps the nearest analogy in common use is that of a computer. Each computer has a hard disc within which can be installed many soft ware programs proper deployment of which enables the computer to provide its owners with many options for use. Each living human cell has a structure within which the genes are housed that is to all intents a mimic of a hard drive. Each cell in addition has a particular set of genes active which can be thought of as evocation of a soft ware program. Liver cells have a particular pattern of genes active and different kinds of cell in the liver have different patterns of gene activity. Genes sometimes change by a process that is called mutation and, when they do, in some instances tumours arise from cells that carry the changed genes.
The genetic concept is not simple to grasp immediately but if one concentrates on the fact that genetic information is required to make things work in living organisms it is not too difficult to realise that if the genetic apparatus goes wrong there may be trouble. Genes are made of a complex set of chemical entities called DNA.
There are many ways that the genetic apparatus can go wrong most of which will be lethal to the cell in which a defect has appeared. However that are also many viable but abnormal changes known in the genetic apparatus of living cells. In broad terms these could be thought of as genetic dysregulation.
For over forty years it has been possible artificially to transfer genetic material between bacteria using bacterial viruses, phages, as carriers of the genes concerned. The concept is a little like that of posting a letter through someone's letter box. There is quite specific information in the letter that can lead to things happening. The bacteriophage has grafted into it a particular piece of genetic information. The phage can get access to bacterial cells by a special mechanism and it carries with it the message to be transferred. Inside the bacterial cell the virus or part of it becomes integrated with the host's genetic material. The new message is now part of the bacterial cell and if it is read out then quite specific action will follow - a new protein molecule will be produced. Almost in the same way this means of genetic transfer can now be accomplished in mammalian cells. If the cells that receive new genetic information are defective in some way and the introduced genetic information remedies this defect then gene therapy is said to have been effected. A great hope for the future is that in many circumstances in which alterations of the genetic material are responsible for disease then by various means genetic engineering will enable normality to be restored.
The art of manipulation of the genetic constitution by such procedures as gene therapy or other methods that all specific genes to be blocked or deleted is referred to as genetic engineering.
H
Deriving from the blood. In the present context used to refer to certain classes of stem cell (q.v.)
This rather formidable word simply means blood forming. The bone marrow is a classic (but not the only) example of an haematopoietic organ.
Soon after the first atomic bombs were dropped it was realised that many people died because the radiation generated from the bombs destroyed the blood forming, haematopoietic, tissues. A lot of work was undertaken to see if there was any way this effect could be avoided (apart from not dropping atomic bombs). It was discovered that if undamaged haematopoietic tissue (usually a suspension of bone marrow cells) was injected after radiation sometimes the injected cells took over from the ones damaged by radiation. What were formed were said to be haematopoietic chimaeras with cells deriving from two different organisms, the irradiation damaged host and the undamaged bone marrow donor. From this unpromising start it was realised that in circumstances where the cells in the bone marrow had become cancerous it might be possible to destroy them by radiation and restore blood forming function by an injection of unirradiated cells. Thus radiation chimaerism could be looked upon as a potentially therapeutic aim.
Inflammation of the liver, caused by infectious or toxic agents usually leading to jaundice, fever, liver enlargement, and abdominal pain.
At least five different viruses, HEPA, HEPB,HEPC, HEPD and HEPE can infect liver cells and there cause inflammation . Infection with some of the viruses, HEPA and HEPD and HEPE is usually followed quickly by symptoms that can be recognized leading to rapid diagnosis. HEPB and HEPC often infect asymptomatically in the first instance. Our prime interest here is HEPC that infects at least three hundred million people world wide, the majority of whom probably do not know they are infected. In common with the other viruses, except HEPE, HEPC virus infections very often are long lasting and termed chronic. A substantial proportion of those infected with HEPC after any time between ten and forty years later develop cirrhosis of the liver and/or tumours of the liver. HEPC infections in nearly all instances are associated with people sharing needles and/or poor medical practice during the course of which infected blood is transferred by accident from one patient to another.
Most veins run from tissues and organs to the heart. Arteries run the other way from the heart to organs and tissues. Portal veins are unusual in that they run from between organs of which one is not the heart. In mammals, such as man, there is only one portal vein that runs from the intestine to the liver. It is a highly important blood vessel and when it is in bad condition there can arise many problems.
It was shown in mice that if a relatively large volume of fluid containing a plasmid was injected the plasmid was retained in liver cells and the product derived from the genetic construct could readily be detected. To explain this effect it was proposed that the effect of the injection was to cause a transient heart failure and retrograde flow of blood from the arrested heart into the hepatic vein. The refluxed fluid burst into the fabric of the liver and it was found that large amounts of it were taken into liver cells where the plasmid became incorporated in the genetic material and commenced doing what it was designed to do. Professor Habib realised that the method though effective could not be used in larger organisms including man without modification. He demonstrated that if he inserted a catheter through the femoral vein he could position it by manipulation under imaging in the liver. There he could inflate a balloon collar on the catheter to prevent retrograde flow of injected fluid and deliver a pressurised high volume of fluid containing a plasmid into the body of the liver. What had been done in mice could be done in pigs and humans but with no heart failure and no toxicity as Professor Habib went on to show.
Inventors have to safeguard their inventions by registering them in various ways as intellectual property in relation to which their rights are safeguarded by law. Those working in medical research have the same kind of problems and often when they make a discovery that could be developed into something that makes money before they publish the work they try to safeguard the IPR. R stands for rights. Sometimes this can be done by patenting.
Just as a shadow offers an image of the size and shape of a human body, so can many of the internal organs of the body be imaged using a wide variety of forms of energy that can penetrate the human body but which are differently absorbed by different tissues. X-rays offer a familiar form of imaging widely used for example to indicate bone fractures. Ultrasound is used to show babies in the womb with great precision - a form of imaging almost all have seen directly or on television. Imaging is widely adopted to see the shape, size and number of tumours.
J
K
L
In common with most other organs in the body, tumours can arise from the constituent cells of the liver. In addition, and more commonly, cancers found in the liver were started in other organs of the body, often the colon.
Cells and fluid which escape from the vascular (blood) system of the human body and which are not outside the body will normally get back in via the lymphatic system. This is a low pressure collecting system that drains though a series of ducts back into the blood system.
M
This is an adjective applied to tumours that have the potential to go on an kill their hosts. Commonly malignant tumours have the capacity to invade adjacent normal tissues and organs and often to metastasise, see below.
Tumours originate as single cells growing by cell division into a cell mass that is often detected as a small lump. Usually tumours are detected when they have many millions of cells. A small tumour in the breast, for example, that is one centimetre in diameter will contain around two billion cells the product of nearly thirty divisions from the aberrant cells that started the tumour. Tumours have the capacity to invade and sometimes destroy the tissues adjacent to them but, more insidiously they often shed cells into the blood or lymphatic tissues a very few of which start to form in locations in which they are, as it were, washed up, new, metastatic, tumours. The majority of tumours that kill their hosts, the person on which they are growing, do so because of metastatic spread and growth of so-called secondary tumours rather than from growth of the primary tumour.
The study of living organisms at the molecular level could be called molecular biology but in fact the term has arisen in recent years from an increase in our capacity to identify the genetic elements of cells and in many instances operate in such a way as to change or regulate their behaviour. Thus molecular biology is concerned with the biology of macromolecular aggregates in living cells rather than individual small molecules that are usually dealt with by biochemists.
In recent years there has developed a sophisticated set of technologies that allow measurement of many Liverdisease-Unlimited - Academicaspects of function of the human body by reference to microchips that can be installed within the body itself. For example the liver assist device referred to in the academic and clinical sections of this web site has, mounted on the head of the pump, chips that can make an estimate of blood flow and also measure various aspects of liver function. The information from these chips is obtained by telemetric devices that, outside the body, can receive and translate messages from the chips that are inside the body.
N
O
Two or more tissues working together to discharge a single function are called an organ. The brain, liver, kidneys and intestine are all examples of organs that have many constituent tissues.
P
Pegylated interferon is a man-made form of interferon, a chemical naturally produced in the body to fight viruses. Interferon helps to stop the hepatitis C virus (HCV) from making new copies of itself. It also helps the immune system to kill HCV. Pegylated interferon is made with special add-on parts that help the drug stay in the body longer. It is injected once a week, while interferon that is not pegylated needs to be injected three times a week.
This is an adjective used to describe stem cells that are capable of producing differentiated cells of a number of different kinds whilst still maintaining their basic stem cell characteristics..
Tumours develop from single cells by more or less uncontrolled replication . Tumours discovered in their site of origin are termed primary tumours. When tumour growth occurs quite often metastatic spread occurs to form secondary tumours.
Tumours change with time usually to the detriment of their host organisms. The changes are often behavioural and are caused by alterations in the genetic material of single tumour cells additional to those that occurred prior to the inception of the original tumour cell mass. The changes that can occur in a tumour with time are often referred to as progression. Refer also to primary and secondary cancers.
Q
R
Living cells usually have the capacity to divide into two in a process that is commonly called replication. This term is adopted because often the cell division produces two cells that superficially are the same, thus a replica has been produced. In addition there is a very precise procedure for insuring that the two cells produced have the same genetic material. Clearly this does not happen all the time otherwise we should all be big blobs of homogeneous cell masses.
A tumour that a surgeon decides he can cut out is termed resectable.
S
Tumours arising by replication from metastatic cells are said to be secondary to the primary tumours from which they originated
The concept of stem cell derives from the dictionary definition of a stem as a central point from which other things derive, in relation to plants, for example, the central axis of the organism from which other shoots, leaves, buds and flowers derive. Thus a stem cell is a cell from which other and often different cells may derive but which retains its stem like nature in being able to act as a further source of new stem cells and differentiated cells. In organisms like human beings, which are here our prime concern the zygote which is the product of fusion between a sperm and an egg is a single cell from which in the fullness of time derive the seventy trillion or so cells that form an adult human body. Within this enormous mass of cells are many cells that act as stem cells. Some of them, in the bone marrow, for example, are capable of generating the many kinds of cells that are found in the blood and in fact many other places even the liver!. The bone marrow stem cells in some instances exercise their capacity to generate other and different cells in the marrow itself all the time retaining their stemness in the sense that they can continue to generate cells unlike themselves and yet retain their own identity. Some of the stem cells are shed from the bone marrow and in various parts of the body they can exercise their capacity for proliferation and occasionally replacement of cells that have become destroyed or perhaps simply worn out to the point where they are not functioning properly. There are in addition to these circulating, haematogenous, stem cells many other stem cells that are found only locally in for example such organs as the skin, breast liver and brain. These stem cells may normally be involved in the process of repair of degenerate tissues rather in the same way that a car body specialist may repair the side panels of a car that have over the years been destroyed by rust. As far as the liver is concerned we know that some kinds of cell are replaced by proliferation of local stem cells and we also know that sometimes haematogenous stem cells can be involved. What we do not yet know is how to intervene in these regenerative processes in such a way as to benefit the patient in whom things are going wrong and, for example, cirrhosis of the organ is evolving.
T
Research results are often not adequate for application in the real world outside the laboratory. The process of moving research results to their point of application is referred to as technology transfer.
Tissues are similar cells devoted to single functions. Two or more tissues collectively form and organ. Thus a liver is an organ with hepatocytes, bile duct epithelial cells, blood vessel epithelial cells, Kupffer cells and many other tissues. Replacement of defective tissues can sometimes be managed in attempting to restore function to an organ that is not working optimally. Such attempts are often referred to as tissue engineering.
U
V
Vaccinia viruses can cause small pox and it is from the use of cow-pox virus to immunise against small pox that the name vaccination derives. It is often used in circumstances when no vaccinia viruses are involved. The assumption is that interaction with the cow pox virus makes the vaccinated organism capable of resisting any further attack by pox viruses.
The plumbing system that carries the blood round the body is called the vascular system. In humans and indeed in all organisms with a backbone, vertebrates, the vascular system is termed a high pressure system. Partly as a consequence of the high pressure, cells and fluid escape from the vascular system into the extra-vascular spaces from which they are collected by a low pressure lymphatic system
W
It is common for geneticists to talk of the natural genetic condition as the wild-type to distinguish it from mutant forms in which mutational change to the genetic material has occurred. Wild-type is also often used for infectious organisms that are distinct from their attenuated forms that are less harmful infections.
XYZ