Biomedical Research

What would we do without anaesthetics

General anaesthesia(scientifically known as narcosis) is the act of putting a patient to sleep, which induces complete unconsciousness. Its function is to prevent the patient’s awareness during surgery by suppressing reflex activity, which causes surgical interventions to be easier, and ultimately allows comfort to the patient. The development of anaesthetics has a unique and fascinating history.

William Morton, a dentist who was residing in Boston, US, was behind this turning point in surgery. He allows his patient Edward Abbot, who had a tumour in his neck,  to inhale diethyl ether. When he was asleep, the surgeon John Warren removed the tumour.

However despite such revolutionary  surgery, there was a long period of time before general anaesthesia was fully adopted into surgeries. At the time many surgeries were opposed to anaesthetics as believed they were dangerous or possibly a waste of time and ‘quick surgeons’ did not require them.  Before the discovery of anaesthetics, surgeons were required to act with haste and create incisions quickly to reduce the duration of pain for the patient. However this all changed after Queen Victoria had anaesthesia during the birth of her eighth child-Prince Leopald. The anaesthetist responsible was called John Snow. John Snow had already written a book beforehand about ether and chloroform and he had designed a mask which can be used to administer chloroform, which was not permitted to be used in the Queen’s pregnancy. Therefore Snow laid a clean handkerchief on top of her nose and used a pipette to release chloroform drop by drop onto the handkerchief. He released chloroform until she indicated that she felt no pain. He gave 15 drops of chloroform on the handkerchief with every contraction. Snow recorded that ‘Her Majesty expressed a great relief from the application’ and ‘the pains being trifling during the uterine contractions, and whilst between the periods of contraction there was complete ease.’ The Queen described it as ‘soothing and delightful beyond measure’. (LAAR, 2019)After this, anaesthesia grew in popularity all over Europe. However despite its continent wide fame, the Lancet, a prominent medical journal, criticised the use of chloroform in Queen Victoria’s pregnancy. (Anesthesia and Queen Victoria, 2022)

The anaesthetic procedure

It is no surprise that we no longer use ether on a handkerchief as an anaesthetic like John Snow did 200 years ago. Some may assume that a narcotic is sufficient for the pain to be completely repressed, however a narcotic does not prevent increased heartbeat. Therefore analgesics are also given to the patient(usually opium derivatives as they tend to be the most powerful kind). A muscle relaxant is also administered to prevent muscles from tensing during the operation. A ventilator is used and a tracheal tube is inserted via the nose, so it can pass through the trachea. The anaesthetist also checks for more factors such as urine production, oxygen content in the blood, carbon dioxide content in the exhaled air(this is done via a blood pressure band and electrodes placed in the chest and finger) and blood sugar level.

Although many years have passed since William Morton’s discovery , the complete mechanism of anaesthesia is still not fully understood. The anaesthetic state consists of  components  such as unconsciousness, immobility and analgesia.  

There are two types of receptors which are responsible for anaesthetic action: transmitters and ion channels. Cells in the brain communicate via neurotransmitters: neurotransmitters which respond to electrical signals are released into synapse. Based on their function, they can be excitatory neurotransmitters or inhibitory neurotransmitters. Excitatory inhibitors such as glutamate cause depolarisation. Depolarisation is when a gated sodium ion channel opens without warning and allows sodium ions from outside of the membrane to enter the cell.  Inhibitory transmitters such as glycine  causes postsynaptic activity. The type of neurotransmitter with the most significant role in the functional site of anaesthetics is the GABA A receptors. Activation of GABAA receptors leads to hyper-polarisation of the brain, which reduces the excitability of the neurons. GABAA is the major inhibitor receptor in the CNS. GABA receptor has 5 subunits which merge together to form a chlorine channel. Volatile anaesthetic agents have an agonistic  effect (a drug that binds to the receptor, producing a similar response to the intended chemical), however ketamine has an antagonistic effect(unintended effect) on GABA receptors. Glycine receptors are another type of receptor which are located in the CNS, specifically in the spinal cord. When the inhalation anaesthetics bind to glycine receptors in the spinal cord, the inflow of chloride ions is increased so that the painful stimulus is reduced. Another example of receptors are serotonin receptors that lead to membrane depolarisation and cause the excitability of neurons. The activation of serotonin receptors by anaesthetic agents lead to an altered state of consciousness. (Son, 2010)

In conclusion, the discovery of anaesthesia was a significant revolution in surgery as  surely it must have been very difficult for a surgeon to operate on a screaming patient with tensing muscles. Before anaesthesia, surgery was only done for those living in excruciating pain who are close to death. Surgeons must have been disturbed by the patients in agony and therefore operations were done very rapidly. The only advantage of this was that a quicker operation reduces the level of infection. Due to this prominent discovery in 1846, many more operations have been performed, as a result of the elimination of one of mankind’s greatest fears-pain. 


1. 2022. Anesthesia and Queen Victoria. [online] Available at: <; [Accessed 24 March 2022].

2. Son, Y., 2010. Molecular mechanisms of general anesthesia. Korean Journal of Anesthesiology, 59(1), p.3.

3. Van de Laar, A., 2019. Under the Knife. pp.133-137.

Biomedical Research Health and Disease

Why should we not underestimate the role of epigenetics in treating cancer?

Over the last several hundred years, we have witnessed marvellous breakthroughs in genetics. From the works of Charles Darwin to Mendel, there is no doubt that these theories have moulded our understanding of genetics today. However a recently emerging area of scientific research could add to our understanding of genes. Epigenetics is an emerging area of medical research of how our behaviour and environment can change the way genes work. Epigenetics cannot alter our DNA sequence, however it can affect how the body reads the DNA sequences.

In the 18th century, the French scientist Lamarack argued that acquired genes can be transmitted. However he believed that this was the sole basis of inheritance which we know is not to be the case. Whereas in Darwin’s theory of evolution, he suggested that lifetime experiences could lead to the formation of gemmules which attached themselves to egg and sperm, hence affecting offspring. 

How do epigenetic mechanisms work?

Epigenetic changes affect how genes are expressed. There are various epigenetic mechanisms which can occur in our bodies. DNA methylation and histone modification are examples of these mechanisms. 

DNA methylation is the addition of a methyl group to the 5th carbon of cytosine residues( which are linked by a phosphate to a guanine nucleotide ) catalysed by DNA methyltransferases. Consequently this forms 5-methylcytosine.  The cytosine residue linked to the nucleotide is known as a CPG dinucleotide. The methyl group is obtained from the methyl donor S -adenosine methionine. Levels of this methyl donor(SAM) depend on the intake of vitamin B12, B6 and folic acid. The methylation of these cytosine residues to form 5-methylcytosine significantly influences cell differentiation. The methylation of CPGs in the promoter region is associated with gene repression. Methylation is known to turn genes ‘off’.

Similar to DNA methylation, histone modification does not alter the DNA sequence however it modifies its availability to the transcriptional machinery. Chromatin consists of histones and DNA. An example of a well known histone modification is the histone acetylation of lysine. Acetylation neutralises  the positively charged lysine residue in the histone tail: this reduces the strength of the bond between the DNA and histone tails. This causes it to be more accessible to transcription factors.

Causes behind epigenetic marks

Epigenetic marks can be affected by exposure to various metals. Experimental analyses have shown that there were DNA methylation changes after arsenic exposure.Arsenic can be found in rocks, soil and insecticides. Another metal which is shown to have caused epigenetic alterations is cadmium. Cadmium toxicity mechanisms can cause epigenetic alterations during embryonic development : a set of genes responsible for transcription regulation control have shown changes in DNA methylation associated with concentrations of cadmium in pregnant women. Cadmium can be found in soil, and contaminated water, as well as through diet, for example through cereals, vegetables and smoking.

Furthermore air pollution can affect the epigenome. Exposure to atmospheric pollutants can lead to changes in DNA methylation of immunity and inflammation genes, which has been associated with reduced lung function and thus lung cancer. Benzene is also associated with changes of DNA methylation. Low-level benzene exposure has been linked to blood DNA methylation changes such as a decrease in DNA methylation of the genes LINE-1 and MAGE-1: this could increase the risk of developing acute myelogenous leukaemia.

Diet also can influence epigenetic mechanisms. A reduction in calorie intake might attenuate the epigenetic changes which occur during ageing. Smoking can also result in epigenetic changes. At specific parts of the AHRR gene, smokers typically have less DNA methylation than non-smokers. After a smoker quits, the smoker tends to have increased DNA methylation at this gene.

Epigenetic marks: a cause behind cancer

The first human disease to be linked to epigenetics was cancer. Researchers found the diseased tissue caused by colorectal cancer had less DNA methylation than normal tissue. In normal cells,  CpG clusters(known as CpG islands) are normally free of methylation. However, in cancer cells, these CpG islands are excessively methylated, leading to  genes turning off that should not be silenced . This typically occurs in the early stages of cancer. 

Excess methylation of the promoter of the DNA repair gene MLH1 causes a microsatellite (a repeated sequence of DNA) to become unstable  by shortening or increasing its length. This has been linked to many cancers such as gastric, endometrial and colorectal cancers.

Epigenetic Treatments

At present, two classes of epigenetic drugs have been approved by the FDA, DNA methylation inhibitors and histone deacetylase inhibitors. The first approved drug was 5-azacitidine.

5-azacitidine is an analog of cytidine, with a nitrogen atom in the position of the 5th Carbon. Cytidine can be incorporated into DNA and RNA. Due to 5-azacitidine’s similarity to cytidine, both compounds are recognised by DNA and RNA polymerases, therefore the drug is incorporated into the DNA during replication. The drug is recognised by DNA methyltransferase. The DNA methyltransferase transfers a methyl group as usual. However as the nitrogen is in the fifth position this causes a permanent  bond between the DNA methyltransferase and 5-Azacitidine. This causes DNA methyltransferase to degrade, which leads to the reduction in methylation . The drug had a high level of toxicity when tested on mice. Hence the drug is now given in low but repeated doses so the epigenetic effects can occur without a high level of cytotoxicity.



RG108 is a non-nucleoside analog which specifically  targets DNA methyltransferases. This interacts with the catalytic domain(the region of an enzyme that interacts with its substrate to cause an enzyme reaction), and then blocks its active site with a low level of cytotoxicity.  Unlike nucleoside analogs like 5-Azacitidine, non-nucleoside analogs do not incorporate themselves into DNA. Therefore they do not induce any toxicity.



In conclusion, epigenetics has significantly added to our understanding of how environmental influences can affect whether and how genes are expressed.  Epigenetics drugs have a great potential to be effective against a number of cancers by reversing epigenetic mechanisms. The field of epigenetics will continue to grow, enabling scientists to develop more targeted drugs against cancers.


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·       Toraño, E., García, M., Fernández-Morera, J., Niño-García, P. and Fernández, A., 2016. The Impact of External Factors on the Epigenome:In Uteroand over Lifetime. BioMed Research International, 2016, pp.1-17.

·      Hamilton, J., 2011. Epigenetics: Principles and Practice. Digestive Diseases, 29(2), pp.130-135.

·      Centers for Disease Control and Prevention. n.d. What is epigenetics?. [online] Available at: <; [Accessed 19 February 2022].

· 2008. Epigenetic Influences and Disease | Learn Science at Scitable. [online] Available at: <; [Accessed 19 February 2022].

·      Lanata, C., Chung, S. and Criswell, L., 2018. DNA methylation 101: what is important to know about DNA methylation and its role in SLE risk and disease heterogeneity. Lupus Science & Medicine, 5(1), p.e000285.

·       Heerboth, S., Lapinska, K., Snyder, N., Leary, M., Rollinson, S. and Sarkar, S., 2014. Use of Epigenetic Drugs in Disease: An Overview. Genetics & Epigenetics, 6, p.GEG.S12270.

·      Ganesan, A., Arimondo, P., Rots, M., Jeronimo, C. and Berdasco, M., 2019. The timeline of epigenetic drug discovery: from reality to dreams. Clinical Epigenetics, 11(1).

·      Science Direct. 2016. N Phthaloyltryptophan. [online] Available at: <; [Accessed 19 February 2022].

·       Zheng, Z., Zeng, S., Liu, C., Li, W., Zhao, L., Cai, C., Nie, G. and He, Y., 2021. The DNA methylation inhibitor RG108 protects against noise-induced hearing loss. Cell Biology and Toxicology, 37(5), pp.751-771.

Picture Credits:

·      n.d. Azacitidine. [image] Available at: <; [Accessed 27 February 2022].

·      n.d. RG108. [image] Available at: <; [Accessed 27 February 2022].