Immunology

Professor Or Serial Killer? The Sequel

Various tasteful games are played in life. Some of them range from Drummer Or Serial Killer? to Professor Or Serial Killer?

I’d like to introduce a new variation: Medication Or Elf From The Lord Of The Rings?

Levemir: Medication Or Elf?

This is…

(obligatory drum roll)

…a medication. It’s a form of long-acting insulin.

Ritonavir: Medication Or Elf?

This is…

(next obligatory drum roll)

…also a medication. It’s an anti-HIV agent whose mechanism is HIV-1 protease inhibition.

References

  1. NPS Medicinewise. 2020. Levemir FlexPen. [online] Available at: <https://www.nps.org.au/medicine-finder/levemir-flex-pen-injection> [Accessed 2 February 2021].
  2. NPS Medicinewise. 1997. Ritonavir. [online] Available at: <https://www.nps.org.au/australian-prescriber/articles/ritonavir> [Accessed 2 February 2021].

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Of Mice And Men Inoculating Mice With Viruses

In an experiment involving the ever-unfortunate mice, the following steps occurred:

  • Mice inoculated with influenza virus
  • Th17 cells activated and migrate to respiratory and gastrointestinal systems
    • Both respiratory and gastrointestinal tracts have mucosa, so they are similar in a way
  • Th17 cells produce cytokines IL-17A and IFN-γ
    • These cytokines mess with intestinal bacteria
    • Results in less Lacto-, more Entero-
  • Intestinal injury

References

  1. Racaniello, V. (2014). How influenza virus infection might lead to gastrointestinal symptoms. [online] virology blog. Available at: http://www.virology.ws/2014/12/10/how-influenza-virus-infection-might-lead-to-gastrointestinal-symptoms/ [Accessed 5 Feb. 2020].

Warfarin And Antibiotics Interactions

Mechanisms

  • Antibiotics kills intestinal bacteria that make vitamin K
  • Antibiotics inhibit CYP450 enzymes that normally metabolise warfarin

Result

  • Increased INR

References

  1. Baillargeon, J., Holmes, H. M., Lin, Y., Raji, M. A., Sharma, G., & Kuo, Y.-F. (2012). Concurrent Use of Warfarin and Antibiotics and the Risk of Bleeding in Older Adults. The American Journal of Medicine, 125(2), 183–189. http://doi.org/10.1016/j.amjmed.2011.08.014

Potato Gems Of Medical Trivia

A man walks into Bar UC for refuge. The bartender, Sanjay, provides him with a pocket translator his work experience apprentice fetched for him and the man places his order.

Gynaecomastia

  • Benign proliferation of male breast tissue
  • Caused by hormonal imbalance
    • Not enough testosterone compared to oestrogen
    • Medications inducing this include: spironolactone, cimetidine, TCAs, digoxin chemotherapy, metoclopramide and anabolic steroids
    • Conditions inducing this include: liver cirrhosis through SHBG disturbance, hypogonadism, ageing, tumours, renal failure, hyperthyroidism, starvation because testosterone levels drop but oestrogen remains the same
  • Pseudogynaecomastia is fat
  • Imitators: pseudogynaecomastia, breast cancer, mastitis

Cyclophosphamide

  • Affects rapidly dividing cells, like cancer, hair and gut
  • Side effects:
    • Gastrointestinal: nausea, vomiting, loss of appetite, diarrhoea
    • Hair loss
    • Poor wound healing
    • Weird skin and nails

A lady who is almost 80, her wheelchair and her son pass by the bar. She tells bystanders, “Life is quick! You know why? There is too much sin in the world!”

Pulmonary Hypertension

  • High blood pressure in arteries of the lung
  • Causes:
    • Idiopathic
    • Left heart disease
    • Lung disease
    • Pulmonary emboli
    • Secondary to other random conditions
  • Can lead to right heart failure

Sildenafil

  • Trade name: Viagra
  • PDE5 inhibitor
    • Memory aid: PDE5 and Viagra
    • Mechanism: inhibition of PDE5 enzyme –> inhibits second messenger cGMP breakdown —> nitric oxide-mediated vasodilation
  • Indications: pulmonary hypertension, erectile dysfunction

One of the patrons, an overweight redneck, appears to have something stuck in his ears. His wife looks on unsympathetically.

Corticosteroids

  • Many side effects

An irritated farmer waving a pitchfork is on the television in the bar.

Giant Cell Arteritis

  • Average onset age is 72 and minimum is generally 50
  • Symptoms:
    • Headache
    • Joint pain of shoulders and hips, like polymyalgia rheumatica
    • Facial pain, like jaw claudication
    • Scalp pain
    • Visual changes, like blurred vision and blindness
    • Fever
  • Look for temporal artery biopsy and ESR
  • Treat with corticosteroids

Human Herpesvirus Associations

Sometimes, memory aids and mnemonics fall conveniently into place. Other times, the only way to remember something is through its inconvenience, by taking the opposite of whatever it totally should have been.

HHV-6

  • Associated with roseola
  • Memory aid: roseola has 7 letters, which is inconveniently not 6 but certainly less than 8

HHV-8

  • Associated with Kaposi sarcoma
  • Memory aid: Kaposi has 6 letters, so it is not HHV-6, while Kaposi’s has 8 characters in it

Types Of Multiple Sclerosis

Time heals all wounds except relapsing-remitting MS.

And primary-progressive MS.

And secondary-progressive MS.

And whole bunch of other age-related illnesses, like glaucoma, age-related macular degeneration and malignancy.

At least time is good for adhesive capsulitis, alternatively known as frozen shoulder!

Multiple sclerosis

MS is a chronic disease involving immune-mediated attacks on the central nervous system. Demyelination causes mayhem.

As a parallel, Guillan-Barre acutely affects the peripheral nervous system. When it’s chronic, it’s called chronic inflammatory demyelinating polymyopathy.

Symptoms

Neurological symptoms ensue after the disease has passed a threshold.

  • Optic neuritis, characterised by painful visual loss in an eye
  • Numbness, weakness
  • Ataxia, spasticity
  • Fatigue
  • Pain
  • Sexual and urinary dysfunction, such as detrusor overactivity causing urgency

Clinically isolated syndrome is a one-off presentation of demyelination that can progress to MS.

Investigations

MRI can show brain lesions.

CSF analysis can show inflammation.

Evoke potential measurement can show demyelination.

Treatment

Ongoing: immunotherapy agents.

Acute relapse: high-dose corticosteroids.

Spasticity: baclofen

Spasms: benzodiazepines

Mobility: fampridine

Paroxysmal symptoms: carbamazepine

Urinary symptoms: oxybutynin

Pregnancy

The risk of MS relapse is lower during pregnancy and higher in the first 3 months after giving birth.

Summary of major demyelinating illnesses

Central nervous system: clinically isolated syndrome (acute), MS (chronic)

Peripheral nervous system: Guillan-Barre (acute), CIDP (chronic)

References

  1. MS Australia. (2001). Types of MS | MS Australia. [online] Available at: https://www.msaustralia.org.au/about-ms/types-ms [Accessed 20 Jan. 2018].
  2. National Multiple Sclerosis Society. (n.d.). Definition of MS. [online] Available at: https://www.nationalmssociety.org/What-is-MS/Definition-of-MS [Accessed 20 Jan. 2018].
  3. Johns Hopkins Medicine. (n.d.). Guillain-Barre and CIDP. [online] Available at: https://www.hopkinsmedicine.org/neurology_neurosurgery/centers_clinics/peripheral_nerve/conditions/guillain_barre_and_cidp.html [Accessed 20 Jan. 2018].
  4. Multiple sclerosis. In: eTG complete [Internet]. Melbourne: Therapeutic Guidelines Limited (eTG November 2017 edition); 2017 Nov.

Why Don’t NSAIDs Cause Malignancy?

Do topical NSAIDs increase the risk of skin cancer? After all, NSAIDs dampen inflammation and immune suppression is a factor that can promote malignancy. The answer is no!

For, on the contrary, research focuses more on the potential of using NSAIDs in the fight against cancer. How can this be?

Think of the mechanism of NSAIDs. They’re non-steroidal anti-inflammatory drugs, meaning they’re medications that reduce inflammation without being from the corticosteroid class.

NSAIDs indirectly inhibit prostaglandin synthesis by directly inhibiting COX enzymes. This provides anti-inflammatory effects and analgesia.

Prostaglandins play a starring role in situations such as fever.

In contrast, other things that are associated with increased malignancy risk have different ways of working.

For example, HIV impacts CD-4 T cells.

Meanwhile, chemotherapy agents have different mechanisms. For example, vincristine disruptively acts on microtubules.

Let’s not forget UV rays, which wreak havoc on the DNA process by inducing mutations.

These are just some of the villains of medicine. Thankfully, there are emerging medications that meet them in combat. But that’s a story for another day!

Hypersensitivity Reactions

Type I: Allergy and anaphylaxis

Type II: Cytotoxic and complement-mediated

Type III: Immune complex

Type IV: Delayed-type hypersensitivity

References

  1. McDaniel, B. (2014, November 24). Type 1, 2, 3 & 4 Hypersensitivity. Retrieved from Stomp on Step 1, http://www.stomponstep1.com/hypersensitivity-type-1-2-3-4-urticaria-anaphylaxis-immune-complexes-i-ii-iii-iv/.
  2. Ghaffar, A. Hypersensitivity reactions. Retrieved from Microbiology and Immunology On-line, http://www.microbiologybook.org/ghaffar/hyper00.htm.

Podcast 001: Immunology With Dr Sean Riminton

About the episode

Have you ever wondered what immunology is like? No?

Well, this is awkward.

Assuming you said yes to the above, this episode is for you.

As you go through your medical studies and even hospital training, you sure learn a lot of exciting facts. But who teaches you about real life? Where do you go if you want to learn what it’s like to be an immunologist? Or a gastroenterologist? Or an infectious diseases physician? Or if you want to find out about the hours and challenges and good and bad parts of a specialty?

While the textbooks don’t teach you what life in a specialty is really like, our superb speaker Dr Sean just might.

If you’re a junior doctor looking for a specialty to love or a medical student wanting to know more about your possible future, this is for you.

Podcast

About the guest speaker

Dr Sean Riminton is an immunologist and immunopathologist at Concord Hospital and Royal Prince Alfred Hospital. As well as his specialist clinical work, Dr Sean is an Associate Professor with The University Of Sydney.

Although Dr Sean is much too nice to do any boasting himself, he does boast a range of impressive achievements:

  • Fellow of the National Blood Authority of Australia
  • Advisor to the Plasma Fractionation Review and IVIg Criteria for Use Committee
  • Founding Chair of the Immune Deficiency Foundation of Australia
  • Designed and implemented the web-based ASCIA Register of Primary Immunodeficiency Diseases for Australia and New Zealand
  • Founding investigator on the Australia and New Zealand Antibody Deficiency Allele Study

Music credits

Opening and closing themes by Lily Chen.

About the podcast

How To Win Friends & Influenza features interviews with distinguished doctors across a range of specialties.

It’s designed for junior doctors and medical students who are curious about different specialties and the real life side of medicine, not just the pathophysiology of it.

Hear these guests’ stories and learn from their advice, whether it’s immunology, surgery, gastroenterology or something else you’re interested in.