medical stuff

Just a convenient place for me to share medical-sciencey things and prepare for my medicine interviews. personal blog: http://my-abcs.tumblr.com/

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“The human heart stripped of fat and muscle, with just the angel veins exposed.”

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Sorry!

I've been completely AWOL these past few months, but very soon I will be starting the new chapter of my life that is university, and even more importantly medical school! I'm really determined to keep using this blog as a means of sharing what I'm learning and experiencing as I go through uni, so fingers crossed you will be reading a lot more from me over the next few years!

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Been revising this today - it's amazing how this is happening at most 1000 times in one neurone in just one second.

[fuckyeahmedicalstuff]

How Anesthesia works.

Going into surgery knocked out by general anesthesia is like stepping onto an airplane: You temporarily place your life in the hands of what you hope is a trained professional. Actually, that analogy would hold only if neither the pilot, nor the mechanic, nor even the aircraft’s designer understood what keeps a plane up in the air.

Read More

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So after nearly 6 months of waiting,

I’ve received an offer from Birmingham!!!!!

A*AA though, don’t think I can really use it as an insurance, at least this whole UCAS process is over and I can finally firm UCL :D

Btw sorry about the lack of posts, I've been busy "revising" hah, but yeah need to make sure I get these grades now!

[ucmst-blog]

Structure of an Alveolus

Composed of simple squamous epithelium (Type I cells)

                Very thin, made up of one layer of very flattened cells

                As a result, gas exchange occurs easily through this epithelium

Microphages

Protective cells that removes debris and microbes by phagocytosis

Alveolar macrophage (dust cell) – remove debris and microbes from inner surface of alveolus

Surfactant-secreting cell (Type II cell) – secretes surfactant

Surfacant – mixture of phospholipids and lipoproteins which coats the alveolar surface and lowers the surface tension of the alveolar fluid

Surface tension caused by strong attraction between water molecules at surface of alveolar fluid

Without it, alveoli would have to be completely inflated between breaths

Structure of the Respiratory Membrane

Made up of simple squamous epithelium of alveolus and capillary, alveolar and capillary basement membranes

No interstitial fluid (fluid between spaces)

                Fluid present – pulmonary edema = diffusion decreases

Basement membrane – extracellular material that supports an epitheial tissue

Average width - .5 micrometers

Oxygen and carbon dioxide can easily diffuse across the membrane

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Got an offer from UCL :D !

The minimal stuff I put on here was put to good use :D 

Thank you so much minimal number of followers! 

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Democratic freedom and freedom of speech

Okay, so not related to medicine in a massively obvious way, but I chose this topic for my BMAT essay (looking back I have no idea why...), and I have to talk about the essay in the interview, so I need to delve into this subject further...

Democracy considers every human being equal, irrespective of gender, ethnicity, sexuality, etc. Each human has the same right to determine how their lives are led; no king or emperor should have that determining power over an individual's life.

So according to this, everyone has the right of freedom of speech, as no-one should theoretically have the right to control what someone says. However there must be limitations on this: is it right for the free will of one individual to impede on another's? Or what about if the actions or words of one individual are inciting harm on others? Obviously the extent of freedom of speech cannot reach that far.

For example, preachers or town criers are allowed to share their ideas and beliefs in public (though maybe to the annoyance of others), and rightly so, as historically many important ideas have been shared through people speaking in the street. On the other hand, if people were to stand up and openly incite people to commit crime, or even terrorism, then that would infringe on the safety of others. Or for a more healthcare-specific example, what if someone was consciously promoting and attempting to sell dangerous pills off as medicine? That would take money off vulnerable patients as well as most likely making their conditions worse.

It is definitely a privilege that we have a right to democratic freedom, but that does not necessarily mean that we have unrestricted free will. Ultimately it is the safety and the effect on others which overrides our own self-determination.

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A very simple glance at the NHS reforms

I'm still fuzzy on the finer details of this but I'm hoping that interviewers won't expect interviewees to know a massive great detail on them, we're not doctors yet!

Main points:

Abolition of primary care trusts/formation of GP commissioning consortia.

Greater competition with external providers of healthcare.

Pros/cons:

On the surface, giving the role of funding and management to GPs may seem beneficial. Many doctors have complained that managers are only concerned with cutting costs, and that they do not understand the importance of patient care. However, most GPs have not had any management training or experience, and so their focus may be diverted away from patient and clinical care. They may also have to get private management companies to assist in funding, which will make further setbacks on budgets. What is also worrying is the effect this may have on patient-doctor relationships. Patients may be concerned that their GPs will have financial motives, affecting the quality of care they receive.

Again, on the surface the encouragement of competition can be seen as a good thing - patients will have a greater choice in the type of care they receive. However the main concern is whether or not this would lead to a two-tiered system of healthcare as well as a 'postcode lottery' of services - some areas may have a better availability of services than others depending on what is provided by the private firms in the area, which may only be afforded by a certain (richer) percentage of the population. Another concern is how this increased competition will affect integration of healthcare, which is needed greatly in the care of the elderly as well as those with chronic illnesses.

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A run-through of systemic lupus erythematosus

(this is actually the condition which I suffer from, and so naturally I've mentioned this on my personal statement and therefore I am expecting to be asked about it. It's actually an incredibly complex disease which is still not fully understood, and I still can't get my head round a lot of the pathophysiology around it, but hey-ho I'll try my best.)

Systemic lupus erythematosus, more commonly referred to as SLE or just lupus, is an autoimmune disease. In simple terms, like most other autoimmune diseases lupus causes the immune system to attack the body's own cells and tissues, resulting in tissue damage and inflammation. It is a systemic disease, meaning it usually affects multiple organs and systems, most often the skin, joints, kidneys, liver, and the nervous system. Affected organs and symptoms vary between each lupus patient.

Lupus is around 9 times more common in women than in men, and is more common in those with non-European descent, mainly Hispanic and Asian descent. The specific causes of lupus are still unknown; multiple factors are associated with the development of the disease, including genetic, racial, hormonal and environmental factors (namely UV radiation).

Lupus is notorious for being a difficult disease to diagnose, as it's symptoms often cause it to be mistaken for other diseases. Symptoms vary widely between each individual, and come and go unpredictably, causing further difficulties in diagnosis. Common initial symptoms include joint and muscle pain, fever, oral ulcers, photosensitivity and fatigue. More lupus-specific symptoms include the trademark facial malar (butterfly) rash, haematuria, proteinuria, anaemia, atherosclerosis, and pleural and cardiac inflammation.

The scientific characteristic of lupus is the presence of autoantibodies. The immune system usually produces antibodies against foreign antigens, but in lupus antibodies are produced against the body's own antigens, especially nuclear complement proteins, immunoglobulins and DNA. The main proposed mechanism for the production of autoantibodies involves increased apoptosis (cell death) in tissues - during this increased apoptosis nuclear antigens are redistributed and are displayed on the cell-surface, causing lymphocytes to target antigens which would usually be protected inside the cell, producing antibodies against them. These autoantibodies can then bind to the nuclear antigens, forming antibody-protein complexes. These complexes stick to the lining of blood vessels, such as in the glomeruli of the kidneys, causing inflammation and tissue damage.

Lupus cannot currently be cured, but it is highly treatable in order to prevent flares and reduce their severity and duration. The main medications which are used are non-steroidal anti-inflammatory drugs to prevent flares, corticosteroids to treat flares, and immunosuppressants to control and prevent flares. Mortality in lupus patients has decreased over the last 20 years, which can be attributed to earlier diagnosis, improvement in treatments, and advances in general medical care.

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Consent, competence, confidentiality - the three big Cs in medicine

(big post coming up guys)

For a doctor to carry out any type of treatment or procedure, the patient must be given all the necessary facts and information regarding the treatment or procedure, so that they can make a decision in their own best interest. This is known as informed consent. The doctor must make the following known to the patient:

the different options for treatment and management of the condition (maybe medical or surgical), including the option not to give treatment;

the aim of the planned procedure or treatment;

details of the planned procedure or treatment, including any possible side effects, risks, benefits, and how these could be managed;

the consequences of providing the treatment versus the consequences of not providing the treatment;

details of any other staff and persons involved in the procedure or treatment;

a reminder that the patient can change their mind at any time, or that they may seek a second opinion.

The patient should be given plenty of time to reflect so that they can make an informed decision, and so that they do not feel pressured. Only competent patients can give consent.

Competent patients are able to fully understand any given information and are capable of making a rational and informed decision independently. Competency is mainly used in a legal context. Capacity to consent or mental capacity is similar in meaning, but is used mainly in a medical context. Capacity is formally assessed by doctors and nurses to ensure that a patient is able to fully understand any treatment courses, risks and benefits, and that they can remember the information.

Most adults are considered competent. Exceptions are adults with severe confusion or those who have a serious mental disorder - if a 'living will' was issued at an earlier date, where the patient has explicitly stated how they would like to be treated, then the doctor would have to abide by that decision even if it is not necessarily in the patient's best interests. Otherwise, the final decision will rest with doctors to act in the best interest of the patient. Relatives would then need to be involved in case the patient had any personal or religious beliefs.

Children aged 16 and 17 are presumed to be competent, unless they have mental disorders or other obvious reasons.

For children under 16, Gillick competence or Fraser guidelines will need to be referred to. If the child is deemed mature enough to understand information given to them regarding the procedure and its consequences, then they are able to give consent. If they are deemed competent, then the child can refuse any involvement with his/her parents or guardians. Parents will only need to be involved if the child is not competent, or it the child is in danger and social services/police are involved. However, in England and Wales, a child cannot refuse consent for a procedure or treatment that is deemed in their best interest - the decision would need to be made by the parents. The competency of a child will also need to be assessed in relation to the procedure concerned - if the procedure is considered quite risky (use of general anaesthetic etc.) then the child will most likely be unable to give consent. 

The above information on child competence relates to the issue of confidentiality - if a child is deemed competent and explicitly refuses to involve his/her parents, then the doctor must respect the child's confidentiality, no matter how persistent the parents may be.

Except in specific circumstances, doctors must protect patient confidentiality at all costs. Confidentiality is at the heart of a patient-doctor relationship, and breaching it could have serious consequences for the patient's personal life and his/her trust in the medical profession. It will most certainly result in serious consequences for the doctor.

However there are certain circumstances where breaching confidentiality is considered acceptable:

when implied consent has been given, for example towards fellow healthcare professionals, and other members of the interdisciplinary team, unless the patient explicitly states that they do not want certain colleagues to know.

when medical information is required in legal proceedings, for example if police need access to medical records during a crime investigation. This would require a court order.

when public interest and protection is the priority, for example local authorities will need to be informed of certain infectious diseases (eg. tuberculosis, measles, mumps); suspected child abuse/neglect where the patient cannot give consent to disclosure; informing the DVLA of any condition which may affect the patient's ability to drive.

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The 4 ethical principles of medicine

Autonomy - a patient has the right to have an opinion and be able to make decisions for themselves, as long as the patient is in a position to understand the relevant information in order to make an informed decision.

Beneficence - a doctor must do good and act in the best interests of the patient.

Non-maleficence - a doctor should not purposefully or unintentionally harm his patients.

Justice - patients in similar positions must be treated equally; fairness across a whole population must be maintained, therefore benefits, risks and costs should be distributed fairly.

These four principles can be applied to most problems related to medical ethics - usually an ethical problem is the result of a direct disagreement between at least two of the principles, for example if a patient absolutely refuses a blood transfusion which will save their life, do you, as a doctor, respect their autonomous right or do you go ahead with the transfusion and act in the best interest of the patient?

(if that situation were to arise, the autonomy of the patient would be the overriding principle. However, as the doctor you would:

ensure that they are fully competent and able to make such a drastic choice;

find out exactly why they are refusing the treatment, to see if they are acting under false claims or information regarding the treatment;

ensure that the patient is fully informed of the benefits and the consequences of not undergoing the transfusion;

ensure that they are fully acting on their own decisions and not being coerced, misguided or manipulated by a third party;

before respecting their wishes. If the patient ultimately wishes to die, then as the doctor your job is to make sure they go as comfortably as possible.)

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Organ donation: opt-in, opt-out, or something else?

The UK currently uses an 'opt-in' system under informed consent regarding organ donation. This means that anyone who has not given consent is not a donor. People who wish to become potential donors must 'opt-into' the system, usually through the organ donor register.

In the UK the number of organ donors has remained fairly constant, however there are a rising number of patients awaiting a transplant. There are current discussions and debates on methods to increase number of available organs:

Use an 'opt-out' system: everyone is under presumed consent, where anyone who has not explicitly refused is a donor. This system can be 'soft', where the beliefs of family members are taken into account, or 'hard', where they are not. Spain uses a 'soft opt-out' system; Austria uses a 'hard opt-out' system. Statistically this system would increase donation rate. However, what is controversial with this approach is how it affects patient autonomy - for consent to be valid, the patient needs to be able to fully comprehend any information given, including risks and benefits involved. Therefore under an opt-out system, consent would obviously be breached in vulnerable groups of people, such as children, the mentally ill, the elderly and illiterate. Also, not everyone would be aware that they have the option of refusal, so there may be 'false positives', that is, people who appear to have given consent but who actually object to donation. Another counterargument, albeit a religious one, is that organ-giving should be considered an ultimate gift of generosity, and not a duty that the state assumes. This system is currently being tested in Wales. 

Use a mandated choice approach: under this approach, everyone is required by law to state in advance whether they are willing to donate or not. This should increase donation rate as many people currently avoid or choose not to make a decision. Again, people may find that this approach conflicts with their autonomy; some will believe that it is their autonomous right not to be forced to make a decision.

Widening the types of donors available: the BMA - British Medical Association, have recently put forward controversial proposals to consider new types of donors. These include taking organs from high-risk donors, eg the elderly, using organs from newborn babies who have no chance of survival, or keeping patients alive solely so that their organs can be harvested. Ethical concerns have been raised over whether it is acceptable to keep somebody alive for another person's benefit and not their own.

Other methods: various other suggestions have been raised, such as: reciprocity - where if you require an organ transplant you will have higher priority if you were on the register yourself; some sort of incentive, eg paid-for funeral expenses (though this method has been criticised for being dangerously close to organ-purchase); increasing awareness and public perception through advertising; encouraging hospital staff to identify more dying patients who may donate.

[sciencenote]

Most scientists believe that cancer happens when several genes of a particular group of cells become mutated. Some people may have more inherited mutations than others, and even with the same amount of environmental exposure, some people are simply more likely to develop cancer.

The following types of genes contribute to cancer:

Tumor suppressor genes are protective genes. Normally, they suppress (limit) cell growth by monitoring the rate at which cells divide into new cells, repairing mismatched DNA (a cause of mutations), and controlling cell death. When a tumor suppressor gene is mutated (due to heredity or environmental factors), cells continue to grow and can eventually form a tumor. BRCA1, BRCA2, and p53 are examples of tumor suppressor genes. In fact, nearly 50% of all cancers involve a missing or damaged p53 gene.

Oncogenes turn a healthy cell into a cancerous one. HER2/neu and ras are two common oncogenes.

DNA repair genes fix any mistakes made when DNA is replicated (copied). Mistakes that aren’t fixed become mutations, which may eventually lead to cancer, especially if the mutation occurs in a tumor suppressor gene or oncogene.

DNA Repair Genes A third type of gene associated with cancer is the group involved in DNA repair and maintenance of chromosome structure. Environmental factors, such asionizing radiation, UV light, and chemicals, can damage DNA. Errors in DNA replication can also lead to mutations. Certain gene products repair damage to chromosomes, thereby minimizing mutations in the cell. When a DNA repair gene is mutated its product is no longer made, preventing DNA repair and allowing further mutations to accumulate in the cell. These mutations can increase the frequency of cancerous changes in a cell. A defect in a DNA repair gene called XP (Xeroderma pigmentosum) results in individuals who are very sensitive to UV light and have a thousand-fold increase in the incidence of all types of skin cancer. There are seven XP genes, whose products remove DNA damage caused by UV light and other carcinogens. Another example of a disease that is associated with loss of DNA repair is Bloom syndrome, an inherited disorder that leads to increased risk of cancer, lung disease, and diabetes. The mutated gene in Bloom syndrome, BLM, is required for maintaining the stable structure of chromosomes. Individuals with Bloom syndrome have a high frequency of chromosome breaks and interchanges, which can result in the activation of oncogenes. 

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A run-through of gene therapy

(just to provide more background info for my previous post on haemophilia B gene therapy)

Gene therapy is any therapeutic technique where functioning alleles of genes from DNA are used as a pharmaceutical agent to treat disease. The most common form is the use of DNA to encode a functional allele, replacing a previous, faulty and mutated gene.

The allele has to be placed inside a vector in order to enter and be transcribed inside target cells. Common vectors include viral DNA, bacterial plasmids, and artificial vesicles called liposomes.

There are two types of gene therapy:

somatic - the functional alleles are placed inside somatic cells - normal body tissue cells. Any genetic modifications are restricted to the individual only; they are not passed on genetically.

germline - the functional alleles are placed inside germline cells - sperm and ova. Any genetic modifications may be passed onto children. All cells derived from the target germline cells will also contain a copy of the functioning allele. Germline cell therapy is currently prohibited for human use.

However, there are problems associated with gene therapy, as well as ethical considerations, especially concerning germline therapy:

effects of gene transfer in germline therapy are unpredictable - even if the target disease is cured, further defects may be introduced in the embryo and then to offspring. In somatic therapy this could potentially lead to formation of a tumor if the allele is placed in the wrong part of the genome.

offspring affected by germline therapy on parents had no autonomous decision in whether their genetic material should have been modified.

there are concerns over the use of germline therapy to enhance favourable characteristics, leading to possible eugenic uses through the ability to manipulate the genetic material of  population.

somatic cell therapy is only useful in single-gene defects. Multigene and multifactorial diseases, eg heart disease, diabetes, arthritis, would be especially difficult to treat using gene therapy.

the use of viral vectors carries risks - it may induce immune and inflammatory responses. It is also not known whether a virus, once inside the patient, may recover its ability to cause disease.

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Haemophilia B is a blood clotting disorder caused by a mutation in the Factor IX gene, leading to a deficiency of Factor IX. Factor IX is a protein which plays an important role in the process of coagulation in humans. It is located on the X chromosome; haemophilia B is an X-linked recessive disorder and so therefore it predominantly arises in males.

The six-person study at UCL used the vector adeno-associated virus (AAV) to deliver the Factor IX gene to liver cells. This vector was used as it belongs to a family of liver-targeting viruses, but it also has a low incidence of natural infection. 

Each person received a one-time infusion of the vector into a vein in the arm. Two patients were treated with escalating doses. Following treatment, Factor IX levels rose in all patients from less than 1% before gene therapy to between 2 and 12%. The two patients who received the escalating doses had the greatest increase in Factor IX levels.

The patient who received the highest dose also had a rise in liver enzymes after the infusion, signalling mild liver damage. The patient remained healthy after undergoing successful, short-term steroid treatment. The rise in enzymes is thought to be due to an immune response targeting the vector.

Four of the patients have now stopped receiving protein injections to prevent bleeding and have not suffered spontaneous bleeding since. One patient has remained at a 2% level for Factor IX for more than 18 months.

These results show that similar use of somatic gene therapy could potentially be used to treat other genetic protein disorders, including haemophilia A and cystic fibrosis. Quality of life has been dramatically improved as the patients do not need to fully rely on protein injections. Some have even participated in marathons and other activities that would have been difficult prior to gene therapy.