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Podcast 010: Psychiatry With Dr Philip Boyce

Minds are important things. You need them for study, constructing evil plots, working out how much change you’re supposed to receive at the supermarket and organising social gatherings with your friends.

Just like hearts, souls and a working Internet connection, minds are vital in our modern world. Psychiatry is a discipline of medicine that deals with mental illness and its effects on patients.

In this episode, Professor Philip talks about the interesting topics that psychiatry encompasses, the lifestyle of the work and invaluable wisdom from his years of expertise in the field.

Podcast

About the guest speaker

Dr Philip Boyce is a Professor in Psychiatry with a whole bunch of outstanding achievements. He’s the Head of the Discipline of Psychiatry at the University of Sydney and Head of the Perinatal Psychiatry Clinical Research Unit at Westmead Hospital. His clinical focus is the impact of psychotic disorders on women over the perinatal period and predictors of bipolar relapse following childbirth.

Professor Philip was a member of the working group that developed the RANZCP’s Mood Disorders Clinical Practice Guideline and the Clinical Practice Guideline for treatment of the anxiety disorders.

But there’s more! Professor Philip co-authored the 4th edition of Fast Facts: depression published in 2017 and was awarded the RANZCP’s medal of honour in 2016. He is an associate editor of the ANZJP and enjoys playing golf.

Music credits

Opening and closing themes by Phil Poronnik.

Methadone Versus Suboxone

The major treatment for opioid dependence is opioid replacement therapy.

Two big options exist. Both are given daily under observation.

Methadone

  • Only opioid agonist activity, not antagonist
    • Can be dangerous if IVDU while on methadone
  • Works in special groups
    • Mental health
      • Safe in mental health issues, like schizophrenia
    • Pregnant
      • Not teratogenic
    • Homeless
      • As have more chaotic lifestyle
  • Longer half-life
    • Increase dose more slowly, such after 4 days

Suboxone

  • Combined partial opioid agonist and antagonist
    • Buprenorphine plus naloxone
  • First-line in normal situations
    • Given methadone in pregnancy
      • Buprenorphine has no studies on safety
      • Naloxone is teratogenic
    • Suboxone is considered weaker than methadone
  • Given sublingually
    • So goes to blood
    • Not effective if taken orally through gastrointestinal system
    • Naloxone works as antagonist in blood, not gut
    • Thus, is good if IVDU patient
  • Can increase dose every day, such as after 24 hours

References

  • Doctor from Centre For Addiction Medicine

Trivia About PTH

Just like everybody knows that Andrew Garfield is the best-looking Spider-Man ever, everybody knows what PTH does.

Obviously! Your local supermarket worker knows it! Your angry ex-partner who’s now filing for asset claims from you knows it! The door-knocking salesperson you try to hide from by pretending you’re not at home when they try to pester you knows it!

Parathyroid hormone, affectionately referred to as PTH, is renowned for its action of freeing calcium from bones. But does it do this through osteoclasts directly? After all, osteoclasts eat bone and osteoblasts build bone.

The answer is…

No.

NO.

NO!

PTH indirectly stimulates osteoclasts to resorb bone. Mind-blowingly, it does this through osteoblasts.

References

  1. University Of Washington. (2017). Bone Remodeling. [online] Available at: https://courses.washington.edu/conj/bess/bone/bone2.html [Accessed 30 Jul. 2017].
  2. Zhao, W., Byrne, M. H., Boyce, B. F., & Krane, S. M. (1999). Bone resorption induced by parathyroid hormone is strikingly diminished in collagenase-resistant mutant mice. Journal of Clinical Investigation, 103(4), 517–524. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC408105/ [Accessed 30 Jul. 2017].

Podcast 009: Skin Cancer General Practice With Dr Philip Smith

Skin is important! How else do you discriminate between all of the delicious fruit and vegetables in the supermarket?

When it comes to people, the pathologies can be a little more worrying. In Australia, skin cancer is a real concern. Dermatological conditions can be confusing enough that dermatology is a specialty on its own, yet the topic forms a large part of general practice. It’s possible to study a subspecialty in general practice that allows you to focus on a particular area without going through a different college of medical accreditation.

As a non-science graduate of a city medical program, Dr Philip talks about his deviation from surgery, his subsequent background as a rural general practitioner and his current range of medical duties.

Podcast

About the guest speaker

Dr Philip Smith is a general practitioner who focuses on work as a skin cancer clinician. When he’s not identifying people’s worrying skin lesions with a dermatoscope, he’s assisting with hospital surgeries and spending time with his family.

Music credits

Opening and closing themes by Phil Poronnik.

Diuretics

Types

Carbonic Anhydrase Inhibitor

  • Acts on proximal convoluted tubule
  • Inhibits the enzyme carbonic anhydrase, which is normally involved in the breakdown of carbonic acid into carbon dioxide and water
    • Inhibition of carbonic anhydrase leads to a build-up of bicarbonate instead, as the alternate pathway for carbonic acid metabolism
    • Because there is now too much of it, more bicarbonate is set free into the urine
    • But hydrogen ions are used as currency to exchange for the resorption of sodium ions, so a diuretic effect ensues
  • Examples: acetazolamide
    • The name has “c” and “a” in it

Loop

  • Acts on thick ascending limb of Loop Of Henle
  • Blocks Na+-K+-2Cl- transporter
    • This has four ions in it, just as “loop” has four letters in it, as does the word “four“
  • Examples: frusemide/furosemide

Thiazide

  • Acts on distal convoluted tubule
  • Blocks Na+-Cl- channel, affectionately called NKCC pump
    • This has two ions in it and “thiazide” starts with “t” too
  • Examples: hydrochlorothiazide

Potassium-Sparing

  • Acts on collecting duct
  • Does not evict potassium into urine for an ungracious hypokalaemia like the others
  • Examples: amiloride, spironolactone

Others

Diuresis refers to the increased production of urine. Thus, further substances exist that can exact a diuretic effect but do not work on kidneys in the ways listed above. For example, coffee can have a weak diuretic effect, while that of alcohol is stronger.

Diuretic Actions On Calcium

Loop –> Hypocalcaemia

Thiazide –> Hypercalcaemia

Triple Whammy

References

  1. Chaudhry, S. (2017). DIURETICS AND RENAL HORMONES. [online] McMaster Pathophysiology Review. Available at: http://www.pathophys.org/diuretics/ [Accessed 12 Sep. 2017].

Major Arm Nerves Passing Through Geometric Spaces

Quadrangular space: axillary nerve.

Remember: a is before r in quadrangular.

 

Triangular space: radial nerve.

Remember: r is before a in triangular.

 

References

  1. Hacking, C. and Gaillard, F. (2017). Quadrangular space | Radiology Reference Article | Radiopaedia.org. [online] Radiopaedia. Available at: https://radiopaedia.org/articles/quadrangular-space [Accessed 25 Aug. 2017].
  2. Knipe, H. (2017). Lateral triangular space | Radiology Reference Article | Radiopaedia.org. [online] Radiopaedia. Available at: https://radiopaedia.org/articles/lateral-triangular-space [Accessed 25 Aug. 2017].
  3. Duke Medicine. (2017). Duke Anatomy – Lab 10: Shoulder, Axilla, & Arm. [online] Available at: https://web.duke.edu/anatomy/lab10/lab10.html [Accessed 25 Aug. 2017].

Encapsulated Pathogens

The Glory Of Acronyms

Cheap shortcuts to memorising important facts are a necessary survival mechanism in life.

Fortunately, in this case, there’s the powerful pairing of a nonsensical acronym with several respiratory illness-related pathogens.

When you mix that with pictures of knives, baked beans and a receding water line, anything is possible!

 

SHaNK SPC EBBS

Streptococcus pneumoniae

Haemophilus influenzae B

Neisseria meningitidis

Klebsiella pneumoniae

 

Salmonella typhi

Pseudomonas aeruginosa

Cryptococcus neoformans

 

Escherichia coli

Bacillus anthracis

Bordetella pertussis

Streptococcus pyogenes

 

Not having a spleen increases the risk of or susceptibility to infection with encapsulated bacteria.

 

References

  1. Medbullets Team (2017). Encapsulated Bacteria. [online] Medbullets.com. Available at: http://www.medbullets.com/step1-microbiology/4010/encapsulated-bacteria [Accessed 15 Aug. 2017].

Milky Anaesthetic

Propofol is used in inducing general anaesthesia for surgery. It looks like a syringe full of milky liquid that probably isn’t milk because milk isn’t commonly injected into people’s veins.

Propofol has this unusual appearance because it includes components of egg.

References

  1. Wehrwein, P. (2011, November 7). Propofol: the drug that killed Michael Jackson. [online] Harvard Health Blog. Available at: https://www.health.harvard.edu/blog/propofol-the-drug-that-killed-michael-jackson-201111073772 [Accessed 9 Aug. 2017].

ACE Inhibitors

Let’s learn about a good friend: ACE inhibitors!

Pertinent Facts

  • class of medication
  • used to treat hypertension
  • end in -pril
  • stop ACE from working its magic on the angiotensin I –> angiotensin II conversion
  • side effects: dry cough (due to bradykinin), hyperkalaemia (because of less aldosterone), angioedema (rare and life-threatening)
  • ARBs are an alternative

Further Details

Renin-Angiotensin-Aldosterone System

Renin (from those pesky organs called kidneys) turns angiotensinogen (also known as renin substrate) into angiotensin I.

ACE (whose full title is angiotensin-converting enzyme) turns angiotensin I into angiotensin II.

Angiotensin II has numerous magical properties: vasoconstriction, stimulating aldosterone release and more…so magical!

Dry Cough, Courtesy Of Bradykinin

Angiotensin II normally clears bradykinin. When ACE inhibitors block that, bradykinin builds up and makes the person cough.

Hyperkalaemia, Due To Vicious Subjugation Of Aldosterone

Aldosterone retains sodium and kicks out potassium. Take that, distal kidney parts! That’s where it acts.

Spironolactone, a medication well-known for its alluring gynaecomastia properties, is an aldosterone antagonist. It’s a potassium-sparing diuretic, which means it helps pass more urine without destroying the person’s blood potassium level to low, low amounts.

Let’s return to aldosterone itself, however. Aldosterone is like a vindictive, electrolyte-discriminating landlord that takes in sodium but evicts potassium from the rental property. It’s the excessively muscly security guard who stops that drunken, disorderly potassium from trying to enter the blood club.

Given the above, inhibition of aldosterone causes the opposite of its normal effects: not ejecting as much potassium from the system. Too much potassium is in the nightclub of your blood! That means hyperkalaemia!

Therefore, anything that stops the triggering of aldosterone creates a risk of hyperkalaemia.

But an ACE inhibitor stops angiotensin II from being formed! And that indirectly reduces the triggering of aldosterone that otherwise would have occurred! Hyperkalaemia might ensue! Chaos everywhere!

That explains one of the potential side effects of ACE inhibitors.

Angioedema Is Serious And Bad

If an ACE inhibitor triggers this, the patient can be switched to an ARB, which is an angiotensin II receptor blocker. It achieves a similar effect without as much risk of the side effects of ACE inhibitors.

Well, well, well, ACE inhibitors. We’ve figured you out now!

References

  1. CV Pharmacology. (2017). CV Pharmacology | Angiotensin Converting Enzyme (ACE) Inhibitors. [online] Available at: http://cvpharmacology.com/vasodilator/ACE [Accessed 30 Jul. 2017].
  2. Howarth, D. A. (2017). RACGP – ACE inhibitor angioedema: a very late presentation. [online] racgp.org.au. Available at: http://www.racgp.org.au/afp/2013/december/ace-inhibitor-angioedema/ [Accessed 30 Jul. 2017].
  3. Uptodate.com. (2017). Medline ® Abstract for Reference 63 of ‘ACE inhibitor-induced angioedema’. [online] Available at: https://www.uptodate.com/contents/ace-inhibitor-induced-angioedema/abstract/63?utdPopup=true [Accessed 30 Jul. 2017].