BJA/RCoA PhD Studentship
Investigating the pharmacology of Nociceptin/OrphaninFQ receptors during cerebral ischaemia
Dr Claire Gibson & Prof Dave Lambert
Background
In the UK, there are approximately 152,000 strokes per year with at least one person suffering a stroke every 5 minutes. Strokes occur as a result of blockage to blood flow within a vessel and cause irreversible brain damage. There are no current pharmacological treatments available which can limit the spread of brain damage following the onset of stroke. A novel approach, worthy of investigation, is to determine the role of non-classical opioid receptors following stroke as some evidence suggests their activation is able to inhibit the release of glutamate, an excitatory neurotransmitter which we know is a significant contributor to the cell death that occurs following stroke.
Aims
This PhD will aim to determine if targeting the non-classical opioid receptor (NOP) is able to produce a protective effect, in terms of reduced cell death, following experimental stroke.
Methodology
This PhD will initially use in vitro models of stroke whereby cell culture systems are exposed to oxygen and glucose deprivation and a significant amount of cell death occurs. Using a variety of pharmacological tools, that are able to both activate and inhibit NOP receptors, we will determine how this receptor contributes to the cell death produced following stroke. Once this has been established we will then go on to establish the pharmacological profile and identify the most suitable drug, in terms of receptor occupancy and activation, to be tested in an in vivo stroke model. Experimental animal models of stroke exist in which blood flow to a particular artery within the brain is blocked which results in a specific pattern of pathology. We will use such a model and assess the effect of NOP receptor ligands in terms of their ability to reduce the amount of pathology produced following the stroke. We will also use mice, deficient in the NOP receptor, to ascertain the specificity of any effects observed. The PhD student will receive extensive training in molecular biology, pharmacology and the use of in vitro and in vivo models of stroke. They will add to the declining number of scientists trained in in vivo surgical techniques and will undertake a (2 month) research visit to Italy in order to complete a specific set of experiments.
Implications
This PhD will determine if a novel therapeutic approach, i.e. via NOP receptor activation, reduces the amount of damage produced following experimental stroke.
Please see the NIAA's position statement on the use of animals in medical research.
Improved patient safety with microultrasound: Development of anatomical models for evaluating clinical potential of microultrasound imaging during epidural and regional anaesthesia
Dr Graeme McLeod
Background
Epidural block provides pain relief during labour and after major abdominal surgery. Peripheral nerve blocks numb limbs for surgery such as amputation. Nerve block is an integral component of enhanced recovery, an NHS initiative designed to improve postoperative recovery, by accelerating mobility and early return to normal function, and limiting the side effects of morphine. Epidural and peripheral nerve blocks have benefits and side effects. Our 3 year audit of labour epidurals showed that repeated needle insertions occurred in over a quarter of patients. Serious side effects such as entering blood vessels, entering the fluid surrounding the spinal cord or causing nerve pain occurred in 1 in 60 patients. Our own audit of 1359 patients with epidurals after abdominal surgery showed that pain after surgery was highly variable. One-third of patients had significant pain on awakening after operation, and only 2 out of 5 were pain free for >6 h. Technical problems occurred in as many as 1 in 7 patients. Our meta-analysis of trials comparing ultrasound guidance for nerve block versus peripheral nerve stimulation has shown that ultrasound has better outcomes and reduces the need for general anaesthesia rescue five-fold, but that temporary nerve damage still occurs in 1 in 14 patients. We expect that increasing obesity, medical morbidity and an ageing population will increase the demand for regional anaesthesia in order to optimise individual patient outcomes.
Aims
We are part of a UK team that wishes to redesign interventional needles for anaesthesia. In a study sponsored by RA-UK, we were able to show, for the first time, the internal anatomy of nerves in the laboratory using microultrasound and replicated needle injection into nerves in real-time. We now wish to develop the engineering and design criteria for building new needles for real-time imaging of tissue during epidural and regional nerve block.
Methodology
We wish to validate epidural and peripheral nerve tissue models such as the fresh pork back and soft embalmed cadaver with human anatomy using MRI and the most advanced microultrasound technology. Secondly we wish to establish which ultrasound characteristics and technology are needed to image anatomy at high resolutions within our validated models; thirdly provide real-time images with our larger neurosurgical biopsy needle and fourthly consult widely with regional and obstetric anaesthetists on the best designs and ergonomics needed to introduce this new technology to practice.
What we will measure and how the data will be used
Our validation phase will measure 2D and 3D anatomical distances and relationships using ultrasound and MRI. Ultrasound characteristics measured will include tissue brightness and stiffness, as well as 3D spread of fluid around nerves. We will measure the reliability of our data, and the level of agreement between raters.
Expected outcomes
A clear need exists to develop new technology to improve the efficacy and safety of epidural and peripheral nerve block. We will offer engineering and anaesthetic criteria for building the first next generational epidural and regional anaesthesia needle with ultrasound at the tip.
Please see the NIAA's position statement on the use of animals in medical research.
Identification of genes contributing to malignant hyperthermia and related phenotypes from differential gene expression
Dr Marie-Anne Shaw & Prof Phil Hopkins
Background
Malignant hyperthermia is a pharmacogenetic disorder. Susceptible individuals have an inherited abnormality of muscle metabolism. In every-day life this abnormality is compensated for by other cellular control mechanisms and susceptible individuals have no symptoms. However, when susceptible patients are given inhalation anaesthetics (the most commonly used anaesthetic drugs) muscle cell metabolism is massively accelerated and the compensatory mechanisms are overwhelmed, with potentially fatal consequences. The currently used main diagnostic test for malignant hyperthermia requires a muscle biopsy through a 2-3 inch incision. Genetic (DNA) diagnosis is available for some families but the complex genetics of malignant hyperthermia precludes making this more widely available.
Aims
To identify further genes underlying malignant hyperthermia.
Methodology
This is a laboratory-based project suitable for a PhD student. We are planning a new approach to finding genetic causes of malignant hyperthermia. Up to now, research has focused on looking for changes in the DNA code that determines protein structures. Even using the latest sequencing technology we have been unable to find the defects in 25-40% of malignant hyperthermia families. In this project we will investigate the theory that defects in the parts of genes that regulate protein production can cause or contribute to the development of malignant hyperthermia. Such mechanisms have been demonstrated for other conditions. To measure gene regulation we will measure the levels of messenger RNA (mRNA) in the muscle tissue of patients diagnosed with or without malignant hyperthermia. The mRNA is the template for protein production that is derived by the coding DNA of the genes. To measure gene expression we will use microarray chips that can simultaneously measure mRNA levels from all ~ 20,000 genes. We will further increase the sensitivity of our approach by measuring mRNA levels in muscle before and after exposure to the anaesthetic halothane, one of the triggering drugs of malignant hyperthermia. The data will be analysed using the latest computer algorithms (bioinformatics).
Expected outcomes
We expect to identify new genes potentially implicated in malignant hyperthermia. Confirmation of the role of such genes will require subsequent functional analysis. This training project will enable the student to acquire a range of state-of-the-art molecular biology and bioinformatics techniques.
Implications
The results of this project are likely ultimately to lead to the availability of DNA testing instead of a muscle biopsy in further patients at risk of malignant hyperthermia.
