Study group discussion: MAC deficiency in Waterhouse Friedreichson syndrome

Waterhouse Friedrichson syndrome has which immune component deficient?

MAC
C5-C9

And infections with what organisms are the especially susceptible to?

Gonorrhoea also?

No, just meningococcal

And just neisseria? Ideally, shouldn't there be increased susceptibility to all gram -ve organisms?

It is caused due to haemorrhage in adrenal gland. Waterhouse is not just a primarily immune complex deficient state. It is a manifestation of systemic infection due to meningococcal meningitis

Umm. My book says that patients with meningococcemia who develop Waterhouse..... Are generally MAC deficient.

There isn't susceptibility to other gram negatives because membrane attack complex is a defense against bacteria which can survive intracellularly.
So basically, extracellular lysis by MAC is effective in killing only Neisseria species.

You're susceptible to N. meningitis only because Neisseria gonorrhea has an outer membrane protein. MAC interacts with it and fails to insert in the bacterial membrane.

And then E. Coli and Salmonella have long polysaccharide chains in cell wall and these side chains prevent the insertion of MAC into bacterial membrane.

So MAC is good at killing only one thing - N. meningitidis and the deficiency will predispose you to this one infection only!

If you're talking about an infection that hemorrhages into the adrenals - it has to get really out of control to do that. And MAC deficient patients can't control their Neisseria infections leading to Water House Friedreichson syndrome. So the book is fair in saying those who develop WHFS due to meningococcal infections are usually MAC deficient.

Study group discussion: Artery of Percheron

*a picture of artery of Percheron was posted in the group on which this discussion took place *

That's vertebral arteries combining to form basilar. And again dividing to posterior cerebral arteries.

This is an anatomical variant.. Any odd thing in the picture?

The supply from the right branch of posterior cerebral artery. That seems odd! If it was normal.. It should have a bilateral supply.

Exactly.
It's called artery of Percheron.

What is special about it?

A rare anatomical variant where the thalamic perforator branch supplies both sides of the midline.

Any occlusion and you'll have bilateral paramedian thalamic infarction.

Ohh.. What would be the symptoms?

Yup.. How would unilateral infarction differ from bilateral?

I can't figure out which structure the artery is supplying!
They're thalamic peduncles. Unilateral you'll have sparing on one side. In Bilateral, the structures below the thalamus will be totally cut off from the structures above.

And symptomatically we are talking depending on which relay centre is affected? Or is there a very specific pure motor, pure sensory stroke we get?

Bilateral paramedian thalamic strokes are typically characterized by a triad of altered mental status, vertical gaze palsy, and memory impairment.

Altered mental status can present anywhere on the spectrum from drowsiness or confusion to hypersomnolence or coma...most probably due to damage to the reticular formation.

Vertical gaze palsy suggests mesencephalic involvement.

Memory deficits mostly are due to damage to the papez circuit. ..Anterior nucleus of thalamus is a part of the Papez circuit.
And also the thalamus acts as a 'search engine' for memories.

I looked up a few parts on the net...

That's awesome!

This is what I found in Harrison - Occlusion of the artery of Percheron produces paresis of upward gaze and drowsiness, and often abulia.

I liked the search engine bit. Nice info!

By the way, a similar sounding condition, 'Purtscher's retinopathy' is associated with acute pancreatitis.

How to remember lobular carcinoma spreads to contralateral breast

Hello! A short sweet post for today :D

Mnemonic: LOBUlar
Located in
Other
Breast
Usually

That's all!

-IkaN

Intravenous dreams

You know you have done too many blood collections when you say stuff like, "Dreams are collapsible, like a vein. So make sure you put needle in a good one."

Study group discussion: Dua's membrane

Cool fact: A new layer of cornea is discovered. It's called the Dua's membrane.

The Dua's Layer lies between the stroma and the descmets.

It's said to be acellular.

It was discovered last year by an Indian opthalmologist, Dr. Harminder Singh Dua.

Related post: Layers of the cornea mnemonic

Study group discussion: Pleural tap

Which muscles are pierced in midaxillary line during pleural tap?
Answer:
- Serratus anterior
- External intercostals
- Internal intercostals
- Intercostalis muscle

What are the boundaries of the safety area that we chose for pleural tap?

Answer:
Anterior - Lateral border of pectoralis major
Lateral - Lateral border of trapezius
Inferior - 5th intercostal space
Superior - Base of axilla

It's also called safe triangle.

Related post: Why is atropine given before procedures like drainage of pleural effusion aka pleural tap?

Staghorn calculus mnemonic

Staghorn calculus mnemonic

I remember the word, "MAPS"

M: Magnesium Ammonium Phosphate Struvite stones

A: Alkaline pH (AlkAline has 2 A's, Acid has just 1 A.)

P: Proteus

S: Splitting organisms (Urea splitting, urease producing organisms)

Staghorn calculus

Study group discussion: Vitamins and renal stones

Question: Which vitamin is indicated in treatment of calcium stones?

Answer: Pyridoxine

And which vitamin is avoided in a patient with history of calcium stones?

Answer: Vitamin C, it will worsen calcium stones.

Why?

Answer: Vitamin C increases oxalate in body. Pyridoxine decreases oxalate level in body.

Extra: Vitamin A deficiency too causes stones. The desquamated epithelium in tubules acts as a nidus for stone formation.

Study group discussion: Signs in acute appendicitis

Most commonly asked appendicitis signs

Aaron’s sign: A referred pain or feeling of distress in the epigastrium or precordial region, on continuous firm pressure over McBurney’s point, in acute appendicitis.

Dieulafoy’s triad: Tenderness, muscular contraction and skin hyperaesthesia at McBurney’s point in appendicitis.

Obturator sign: It refers to presence of hypogastric pain on stretching the obturator internus due to its irritation in the pelvis. This test is performed by passive internal rotation of the flexed rightthigh with the patient supine.

Bastedo’s sign : Pain and tenderness in the right iliac fossa on inflation of the colon with air, in cases of chronic appendicitis.

Psoas sign  : It is positive in retrocecal appendicitis. In this, irritation of the of the psoas muscle gives rise to pain when the patient’s right thigh is extended from the flexed position.

Rovsing’s sign  : Pain at McBurney’s point induced in cases of appendicitis, by pressure exerted over the descending colon

That's a good summary. Thanks!

Study link! Clinical features of acute appendicitis mnemonic
http://medicowesome.blogspot.ae/2014/11/clinical-features-of-acute-appendicitis.html

Study group discussion: Vitamin K overdose and deficiency

What's the adverse effect of excess dose of vitamin K, if given in new born?

Answer: Neonates - In infants (particularly premature babies), excessive doses of vitamin K analogs during the first few days of life may cause severe hemolytic anemia; this in turn may result in  hyperbilirubinemia, kernicterus, leading to brain damage or even death.

Study group discussion: Serial interval and communicable period

What is the difference bw serial interval and communicable period?

Communicable period is the one in which the disease is transmitted from one case to another. (Also known as infectivity.)
The patient might have the disease but may not be infectious because of latent phase.

Serial interval is the time period in which the disease manifests from one case to another.

It's different from communicable period because the disease doesn't manifest immediately, so the case might present to you late.

Serial interval = Latent period + communicable period (Roughly)

Study group discussion: Temporal arteritis

A 60 year old male presents with headache, scalp tenderness, painful temples, pain on chewing & visual disturbances.. Diagnosis?

Answer: Temporal arteritis

What tests you would do to confirm the diagnosis?

Answer: Raised ESR, temporal artery biopsy

Treatment?

Answer: High dose steroids like prednisolone!

Temporal artery branch of?

Answer: ECA, the external carotid artery!

Study group experience #15

Structures that pass through the diaphragm mnemonic
Purtscher's retinopathy

Biliverdin
Largest protein and the smallest protein in the human body

Hemolytic disease of new born
Evening rise of temperature in tuberculosis and malaria
Causes of edema

Chloroquine and Behcets disease
Drugs contraindicated in myasthenia gravis
Drugs used in the treatment of Alzheimers disease

Smoking and hernia
Eponymous terms in hernia and mnemonics

Correct order of clinical assessment of the abdomen

More information on the study group

It's amazing studying with you guys, I wish I could update - discuss more often, but internship is really draining me. Trying my best to catch up. Love you all! :)

-IkaN

Study group discussion: Correct order of clinical assessment of the abdomen

Question: During clinical examination of abdomen what is the correct sequence of the following events?
Palpation - inspection - auscultation - percussion.

Answer: You first need to auscultate in abdominal examinations because bowel sounds increase after palpation. So it would be inspection -  auscultation -  palpation - percussion.

When assessing most body systems, the appropriate order is inspection, palpation, percussion, and auscultation. However, with the abdominal assessment, auscultate before you manipulate the abdomen with palpation and percussion. The rationale for this is that manipulation of the abdomen with palpation and percussion may stimulate peristalsis and thereby alter your examination findings. So the appropriate order for the abdominal examination is inspection, then auscultation, followed by palpation and percussion.

Research paper: http://www.ncbi.nlm.nih.gov/books/NBK420/

Extra tips: You wanna ask the patient whether it hurts somewhere and palpate that area last.

While examining abdomen always expose the patient from nipples to midthigh. Also one more important thing is that, abdominal examination is never complete without examination of external genitalia.

Organ of Zuckerkandl.

There are several extradrenal sites where pheochromocytoma occurs, and this, the 'organ of Zuckerkandl' is one interesting site.

It actually is a cluster of bodies,located either at the bifurcation of the abdominal aorta or at the origin of the inferior mesentric artery and they contain chromaffin cells derived from the neural crest.

These are also known as 'paraortic bodies' but differ from 'corpora aortica'(also a chromaffin body)which lies near to the thoracic aorta.

The organ of Zuckerkandl is said to be responsible for secreting catecholamines and other vasoactive substances. It has a function of supplying catecholamines to the fetus especially in the first trimester of pregnancy and regresses usually in the third trimester.



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Study group discussion: Largest protein and the smallest protein in the human body

How many amino acids make up a protein ?

>100 ~ proteins
10-100 ~ polypeptide
<10 ~ peptide

Which protein is smallest in the human body?

Thyroid releasing hormone or TRH should be the smallest protein in the human body, with 234 amino acids. (> 100 amino acids is a protein.)

Smallest polypeptide in the human body should be insulin, with 54 amino acids. (10-100 amino acids is a polypeptide.)

Smallest peptide in the human body should be glutathione, with 3 amino acids. (<10 amino acids is a peptide.)

I concluded these on what I found on Google. Correct me if I'm wrong.

Largest protein is titin in the human body!

Interesting virology fact:-
The largest viruses as Poxviruses measuring 300nm are as large as the smallest bacteria (mycoplasma). The smallest viruses as Parvovirus measuring about 20nm are nearly as small as one of the largest protein molecule, hemocyanin.

Study group discussion: Hemolytic disease of new born

What is immunogenic hemolytic disease of new born?

Answer: In immunogenic type, the immune system plays a role in the pathogenesis of the disease. Rh incompatibility is an example.

What are the causes of non-immunogenic erythroblastosis fetalis?

Answer: Examples of non immunogenic erythroblastosis fetalis are iron deficiency anemia, CMV infection in mother, etc.

Can congenital hemolytic anemia be a cause of non-immunogenic erythroblastosis fetalis?

Answer: Yes.
Though usually, hemolytic anemias don't present till later in life (Mostly because of HbF).
Exceptions would be severe alpha thalassemia in which all 4 alpha chain synthesis is deleted. 4 gamma chains combine, leading to the formation of HbH (Bart's hemoglobin!) They die in utero due to severe hypoxia and hydrops.

Study group discussion: Drugs used in the treatment of Alzheimers disease

Can anyone help me with pharmacological classification of anti Alzheimer's agents?

For Alzheimers, cholinesterase inhibitors.. And a drug called memantine.

NMDA receptor antagonists.

Drugs: Tacrine (tetrahydroaminoacridine), donepezil, rivastigmine and galantamine.
Mechanism: Inhibition of cholinesterase, with a resulting increase in cerebral levels of acetylcholine.

Antioxidants, selegiline, tocopherol (vitamin E), estrogen replacement in females, Ginkgo Biloba extracts are other drugs which may benefit in Alzheimers disease.

Study group discussion: Eponymous terms in hernia and mnemonics

Here's a list of eponymous hernia terms I was sent. I added a few mnemonics to where I could. Others you'll have to memorize!

Gibbon's hernia- Hernia with hydrocoele

Berger's hernia - Hernia in Pouch of Douglas
Mnemonic: Burgers are made of dough.

Grynfelt's hernia - Upper lumbar triangle hernia.

Petit's hernia - Lower lumbar triangle hernia

Cloquet's hernia- Hernia through pectineal fascia
Mnemonic: The hernia is cloaked, peccantly.

Narath's hernia - Behind femoral artery

Hesselbach's hernia - Lateral to femoral artery
Mnemonic: hesseLBAch - Lateral to big artery.

Serofini's hernia - Behind femoral vessels
Mnemonic: SeroFini - Supported by femoral vessels.

Laugier's hernia - Through lacunar ligament
L for Laugier's, L for Lacunar

Tealse's hernia - In front of femoral vessels

Richter's hernia - Part of circumference of bowel wall is gangrenous
Mnemonic: Richie rich has a large circumference pocket of money.
Alternatively, riChter Circumference.

Littre's hernia - Hernia with Meckels's Diverticulum
Mnemonic: Meckels is a congenital defect, found in Little babies.

Sliding hernia - Posterior wall of sac is formed by colon or bladder

Maydl's hernia - 'w' hernia
Mnemonic: M upside down is W.
Phantom hernia - Localised muscle buldge following muscular paralysis
Mnemonic: Phantom for Phantom, P for Paralysis

Spigelian hernia - Through spegelian fascia

Obturator hernia - Through obturator foramen

Femoral hernia - Hernia medial to femoral vein

Beclard's hernia - Femoral hernia through saphenous opening

Study group discussion: Biliverdin

Why biliverdin is reduced to bilirubin? It isn't toxic, it is water soluble.. Then why convert it to bilirubin?

According to some, biliverdin works just fine. Mammals have evolved the energetically expensive, potentially harmful and apparently unnecessary capacity to reduce biliverdin.

According to others, the conversion is not a wasteful process. Bilirubin is a cytoprotectant and that's why biliverdin is converted into bilirubin. It's also a physiological anti oxidant!

Source: http://m.pnas.org/content/99/25/16093.full

About me!

Hello there awesomites! Feels great to write this for Medicowesome :-)

Where to start? Well, I am a total  astrophysics geek. Anything -spacetime,dark energy, black holes, wormholes catches my fancy.That type of guy who loves staring at the starry sky. Just finds amazing how the tiny word 'universe' encompasses the massive expanse lying out there. Loves going to the point where physics meets philosophy.

Likes looking into nothing, thinking and imagining.

House MD fan. Sherlocked.
Christopher Nolan worshipper. Interstellar fanatic.

I have a thing for rare, fancy medical syndromes! Dreams include running a diagnostics department like House. :-p

Talking of music,a Linkin Park fan, like the regular Bollywood music too.

Proud of India and its rich heritage.

Hobbies include driving cars, riding bikes and even bicycling. Gaming included.

Finally, an animal lover,dreamer and a bit of foodie..

-Sushrut



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