Diagnosis and Diagnostics. The principles of Diagnosis go back a long way, from Chinese Traditional Medicine, through Egyptian Medicine, the traditions of Babylonia, through the usual Greek suspects. The word diagnosis is a combination of the Greek words, dia [apart] and gignoskein [recognise], which simply means distinguish or discern. This next quotation is for me the beginning of contemporary diagnosis, but we should not forget the critical role played by the doctor's careful observation of eyes, ears, complexion, mouth, temperature, urine etc etc. It is (as I am always saying) critical to make detailed observations in Science; and the same is just as true in Medicine. Just a thought: observation is probably more important in veterinary practice, since pets usually only talk to their owners, not the vet! Back to the quotation:
"our chemical individualities are due to our chemical merits as well as our chemical shortcomings; and it is more nearly true to say that the factors which confer upon us our predispositions to and immunities from various mishaps which are spoken of as diseases, are inherent in our very chemical structure; and even in the molecular groupings which confer upon us our individualities, and which went into the making of the chromosomes from which we sprang".
This is taken from a famous book entitled "Inborn Factors in Disease", by Sir Archibald Garrod, a household name I assume? (Try Googling "one gene, one enzyme hypothesis" of Beadle and Tatum: it has its roots in Garrod's ideas) What is more surprising is that this was written over 100 years ago and, together with the patient observation methodologies pioneered by William Osler, has remains essentially unchanged today. If you are interested in the history of diagnosis, follow this link to a pdf.The only difference, over one hundred years on, is the technology and a deeper (molecular) understanding of disease mechanisms. A visit to your doctor today to try and get help for "flu-like" symptoms, may trigger a urine, blood and/or oral swab sample.
The presence of abnormal biomolecules including metabolites or proteins in body fluids can provide an indication of the cause of the symptoms. Think of diabetes (mellitus). Here, the disease is caused by the abnormal accumulation of glucose in the blood. This is either a result of a loss of insulin production by the pancreas or an inability of the body to respond properly to insulin. Biochemically, diabetes is the result of: insufficient insulin, abnormal insulin or an insufficient number of insulin receptors, or their malfunction. The presence of glucose is currently self-monitored by obtaining a blood drop (skin puncture) and a dip-stick coated with an enzyme that converts glucose, indirectly to a coloured molecule. What does the future hold? The Wang lab at University College (Sand Diego, UCSD) has been at the forefront of electronics and biosensors (Nano-Bio-Electronics, NBE); and his lab home page is a great place to start looking! One recent highlight has been the development of a glucose sensing "tattoo". The drivers behind such developments include empowering individuals, and thereby preventing a clinical crisis, which of course reduces the financial burden on the healthcare system. I would imagine that such systems might develop alongside the new trend in wearables, such as the apple watch. There is a nice infographic of the mechanism of enzyme linked amperometric glucose sensing here. It seems to me that the three-way convergence of biochemical analysis, microelectronics and wearable digital technology will be a regular feature in the next five years. The close collaboration between the Liverpool Life Sciences UTC and the Studio School couldn't be better placed to prepare students for these exciting developments in the medical sciences.
The challenges facing diagnostics labs. Whatever the technology, the fundamental principles of diagnostics have their roots in analytical sciences (largely chemistry) and in taxonomy, or more appropriately, the ability to differentiate between harmful and harmless cells. Let's consider the detection of E.coli 0157-H7, the cause of serious food poisoning. Detection of E.coli may involve a Gram test (see LHS). This method, developed over 100 years ago and combines Light Microscopy with the use of selective staining by a dye such as crystal violet, which, through a series of steps, shows differential retention by bacterial cells with simple peptidoglycans (gram negative) compared with complex multi-layered peptidoglycans (gram positive). E. coli is gram negative (pink above) while streptococci are gram positive (purple, above). The Gram test is still used today, but it would not distinguish between a harmless strain of E.coli and E.coli 0157-H7. We now have to draw on two more discriminating methods. The oldest method is based on the ability of antibodies to distinguish between molecules expressed differently by harmful and harmless cells. Such differences may be the result of expression of more (or less) of a particular molecule (often a protein), or if you are lucky, the complete presence or absence of a molecule from the harmful/harmless cells. In the case of E.coli 0157-H7, this strain produces a protein molecule that is key to its toxicity, and this gives rise to secondary metabolic difference (sorbitol metabolism), which allows detection of the harmful strain in stool samples. This test requires an experienced microbiologist, and so this is being replaced by more recently tests based on antibody detection of the toxin. As an alternative test, the PCR can be used if primers can be targeted at the toxin gene(s). In fact PCR methods now dominate diagnostics.
So, if the doctor suspects a food poisoning outbreak, the diagnostic labs will carry out a set of phased tests (the cheapest and quickest first) in order to identify the cause, in order to support the doctor's decision to treat, say by prescribing the appropriate antibiotics. However, as the costs of PCR in particular, come down, microbiological testing will probably be reserved for specialist situations. It is important to appreciate that whilst some simple methods are sufficient, molecular methods are expensive, but may lead to rapid treatment that not only saves the patient, but in the long term saves money. The criteria for choice of diagnosis therefore combines discrimination (gram positive or negative is a poor discriminator, when so many infections are known), sensitivity (how much sample is needed for the test?), speed, (how long from the doctor seeing the patient to result) and cost, which cannot be ignored, since we only have a certain amount of money to keep the nation healthy! PCR technology seems to be winning in most situations, although antibody tests remain essential in some situations.
Detecting infectious agents. The link between wearables in health management and infectious diseases was made clear to me during my sabbatical leave at the Liverpool School of Tropical Medicine. As an institution with a primary focus on translating science into society, with a mission directed at some of the poorest and most challenging locations in the world. The senior team at LSTM: Janet Hemingway and Steve Ward, have been keenly aware of the need to integrate developments in diagnostics and smart phone technologies for some time. Even before attempts to develop sophisticated screening methods (as above), the incorporation of "dumb" phones as a means of communication between clinics and patients to issue reminders for medication etc., has been on the LSTM's radar for some time. Dr. Mark Paine, a biochemist at the centre of one such initiative to develop robust and sensitive diagnostic assays in the fight against malaria is increasingly, factoring in the downstream requirements of the technology "in the field". Some of these portables, wearables and general mobile devices will be used in extreme and remote areas, where battery life is a premium. Such electronic needs are similar to the kinds of factors that ultimately determine whether a promising new "drug" makes it to the pharmacists shelf. You can read about the work in Mark's laboratory here and the LSTM's translational work in their Vision document.
An example of the "pipeline developments" for detection of infectious diseases are exemplified by the Q-POC hand-held instruments from Quantum Diagnostics. Here, the aim is to screen for a range of malaria infection types using a microfluidic device that incorporates DNA extraction and gene specific ID via a high speed (5minues) PCR method. I expect the science behind the selection of probes and DNA extraction is robust, but the challenge with such devices is often the limitations of the power supply and battery life. However, I am sure these issues will be overcome in the near future. I hope this has whetted your appetite for the future and I believe our programmes in the Innovation Labs will prepare students for these exciting challenges.
"our chemical individualities are due to our chemical merits as well as our chemical shortcomings; and it is more nearly true to say that the factors which confer upon us our predispositions to and immunities from various mishaps which are spoken of as diseases, are inherent in our very chemical structure; and even in the molecular groupings which confer upon us our individualities, and which went into the making of the chromosomes from which we sprang".
This is taken from a famous book entitled "Inborn Factors in Disease", by Sir Archibald Garrod, a household name I assume? (Try Googling "one gene, one enzyme hypothesis" of Beadle and Tatum: it has its roots in Garrod's ideas) What is more surprising is that this was written over 100 years ago and, together with the patient observation methodologies pioneered by William Osler, has remains essentially unchanged today. If you are interested in the history of diagnosis, follow this link to a pdf.The only difference, over one hundred years on, is the technology and a deeper (molecular) understanding of disease mechanisms. A visit to your doctor today to try and get help for "flu-like" symptoms, may trigger a urine, blood and/or oral swab sample.
The presence of abnormal biomolecules including metabolites or proteins in body fluids can provide an indication of the cause of the symptoms. Think of diabetes (mellitus). Here, the disease is caused by the abnormal accumulation of glucose in the blood. This is either a result of a loss of insulin production by the pancreas or an inability of the body to respond properly to insulin. Biochemically, diabetes is the result of: insufficient insulin, abnormal insulin or an insufficient number of insulin receptors, or their malfunction. The presence of glucose is currently self-monitored by obtaining a blood drop (skin puncture) and a dip-stick coated with an enzyme that converts glucose, indirectly to a coloured molecule. What does the future hold? The Wang lab at University College (Sand Diego, UCSD) has been at the forefront of electronics and biosensors (Nano-Bio-Electronics, NBE); and his lab home page is a great place to start looking! One recent highlight has been the development of a glucose sensing "tattoo". The drivers behind such developments include empowering individuals, and thereby preventing a clinical crisis, which of course reduces the financial burden on the healthcare system. I would imagine that such systems might develop alongside the new trend in wearables, such as the apple watch. There is a nice infographic of the mechanism of enzyme linked amperometric glucose sensing here. It seems to me that the three-way convergence of biochemical analysis, microelectronics and wearable digital technology will be a regular feature in the next five years. The close collaboration between the Liverpool Life Sciences UTC and the Studio School couldn't be better placed to prepare students for these exciting developments in the medical sciences.
The challenges facing diagnostics labs. Whatever the technology, the fundamental principles of diagnostics have their roots in analytical sciences (largely chemistry) and in taxonomy, or more appropriately, the ability to differentiate between harmful and harmless cells. Let's consider the detection of E.coli 0157-H7, the cause of serious food poisoning. Detection of E.coli may involve a Gram test (see LHS). This method, developed over 100 years ago and combines Light Microscopy with the use of selective staining by a dye such as crystal violet, which, through a series of steps, shows differential retention by bacterial cells with simple peptidoglycans (gram negative) compared with complex multi-layered peptidoglycans (gram positive). E. coli is gram negative (pink above) while streptococci are gram positive (purple, above). The Gram test is still used today, but it would not distinguish between a harmless strain of E.coli and E.coli 0157-H7. We now have to draw on two more discriminating methods. The oldest method is based on the ability of antibodies to distinguish between molecules expressed differently by harmful and harmless cells. Such differences may be the result of expression of more (or less) of a particular molecule (often a protein), or if you are lucky, the complete presence or absence of a molecule from the harmful/harmless cells. In the case of E.coli 0157-H7, this strain produces a protein molecule that is key to its toxicity, and this gives rise to secondary metabolic difference (sorbitol metabolism), which allows detection of the harmful strain in stool samples. This test requires an experienced microbiologist, and so this is being replaced by more recently tests based on antibody detection of the toxin. As an alternative test, the PCR can be used if primers can be targeted at the toxin gene(s). In fact PCR methods now dominate diagnostics.So, if the doctor suspects a food poisoning outbreak, the diagnostic labs will carry out a set of phased tests (the cheapest and quickest first) in order to identify the cause, in order to support the doctor's decision to treat, say by prescribing the appropriate antibiotics. However, as the costs of PCR in particular, come down, microbiological testing will probably be reserved for specialist situations. It is important to appreciate that whilst some simple methods are sufficient, molecular methods are expensive, but may lead to rapid treatment that not only saves the patient, but in the long term saves money. The criteria for choice of diagnosis therefore combines discrimination (gram positive or negative is a poor discriminator, when so many infections are known), sensitivity (how much sample is needed for the test?), speed, (how long from the doctor seeing the patient to result) and cost, which cannot be ignored, since we only have a certain amount of money to keep the nation healthy! PCR technology seems to be winning in most situations, although antibody tests remain essential in some situations.
Detecting infectious agents. The link between wearables in health management and infectious diseases was made clear to me during my sabbatical leave at the Liverpool School of Tropical Medicine. As an institution with a primary focus on translating science into society, with a mission directed at some of the poorest and most challenging locations in the world. The senior team at LSTM: Janet Hemingway and Steve Ward, have been keenly aware of the need to integrate developments in diagnostics and smart phone technologies for some time. Even before attempts to develop sophisticated screening methods (as above), the incorporation of "dumb" phones as a means of communication between clinics and patients to issue reminders for medication etc., has been on the LSTM's radar for some time. Dr. Mark Paine, a biochemist at the centre of one such initiative to develop robust and sensitive diagnostic assays in the fight against malaria is increasingly, factoring in the downstream requirements of the technology "in the field". Some of these portables, wearables and general mobile devices will be used in extreme and remote areas, where battery life is a premium. Such electronic needs are similar to the kinds of factors that ultimately determine whether a promising new "drug" makes it to the pharmacists shelf. You can read about the work in Mark's laboratory here and the LSTM's translational work in their Vision document.
An example of the "pipeline developments" for detection of infectious diseases are exemplified by the Q-POC hand-held instruments from Quantum Diagnostics. Here, the aim is to screen for a range of malaria infection types using a microfluidic device that incorporates DNA extraction and gene specific ID via a high speed (5minues) PCR method. I expect the science behind the selection of probes and DNA extraction is robust, but the challenge with such devices is often the limitations of the power supply and battery life. However, I am sure these issues will be overcome in the near future. I hope this has whetted your appetite for the future and I believe our programmes in the Innovation Labs will prepare students for these exciting challenges.
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