Parasympathomimetics (Cholinergics)

These notes are based on this youtube video, double-checked that the information is correct from the book below.

Direct (bind directly to acetylcholine receptors and act like acetylcholine)

Be My Parasympathetic Choline

• Bethanechol (used for Bowel and Bladder emptying in atonic bladders because they increase motility)
• Methacholine (used in asthma diagnosis)
• Pilocarpine (increases sweat, tears and salivation and increases aqueous humor outflow and miosis, so used in glaucoma and dry mouth diseases)
• Carbachol (increases aqueous humor outflow and miosis, so used in glaucoma)

Indirect (act by inhibiting acetylcholinesterase and thereby prolonging effect of acetylcholine)

End in ‘stigmine’

Reversible cholinesterase inhibitors

• Neostigmine/pyridostigmine
• Physostigmine (only one that crosses CNS and can be used in toxicity of atropine)
• Edrophonium (in diagnosis of myasthenia gravis because it is short acting)

Irreversible cholinesterase inhibitors

• Echothiphate (glaucoma)

Reference:

Mycek, M.J.; Harvey, R.A.; Champe, P.C. (2000). Lippincott's Illustrated Reviews - Pharmacology 2nd ed. 

Student Notes: Non-invasive Prenatal Screening for Fetal Anomalies (OBG)

Prenatal screening was (and still kind of is) a bit of a confusing/pain-in-the-bum subject. I've managed to summarize it for myself in a bearable way and share it.

Note: Keep in mind these are all NOT diagnostic and NON-invasive (as opposed to chorionic villus sampling, amniocentesis, etc.)

The indications of doing each test and contraindications are not the topic of this post.

Possible non-invasive screening tests:

1. U/S: measures nuchal translucency:Which is a sac of fluid behind the neck of the fetus. It is present in all fetuses but is increased in those with Trisomy 21. (Figure below)
2. Pregnancy Associated Plasma Protein A (PAPP-A): this is a glycoprotein produced by the trophoblasts and is most accurately measured during the 1st trimester. It becomes less accurate after that and is therefore not measured in the 2nd trimester.
3. Quadruple screen/triple screen/maternal serum screen: which is a blood test composed of 3 or 4 components (depending on which is chosen).

Retrieved from: http://www.ultrasoundscan4d.co.za/pregnancy-scans/nt-pregnancy-scans/

Patterns of Prenatal Fetal Screening
There are a few patterns of doing the prenatal fetal screening. Depending on the detection rate and false positives of each one, a type is chosen during pregnancy.

1. 1st trimester: doing Nuchal Translucency Ultrasound only (the detection rate in Figure 1 below is the lowest)
2. 1st trimester: doing blood screen + Nuchal Translucency (this is also known as the First Trimester Screen and is explained below)
3. 2nd trimester: doing a Triple Screen also known as Maternal Serum Screen or Quadruple Screen,  (the Triple Screen has a lower detection rate than the Quadruple Screen)
4. Done in both trimesters: Integrated Prenatal Screening (this has the highest detection rate of Down Syndrome as seen below at 94-96%)
5. Done in both trimesters: Integrated Serum Screening

Figure 1: Retrieved from http://slideplayer.com/slide/4092725/

Prenatal Fetal Screening Patterns Explained
First Trimester Screening (FTS) (Red in Figure 1)

What is it?It is a combination of both a blood test and an ultrasound (U/S):

1. Blood test:
1. B-hCG
2. PAPP-A
2. U/S:
1. measures nuchal translucency

When is it done? It is a 1st trimester test done at 9-13 weeks gestation

Advantages:

• 1 blood sample drawn only
• Done early (in the 1st trimester) so useful where parent wants early results and can also offer follow up with a Chorionic Villus Sampling if positive, since Chorionic Villus Sampling can only be done between 10-13 weeks of gestation)
• Can detect Trisomy 21 and 18

Disadvantages:

• Does not estimate risk of open Neural Tube Defects (NTDs) and therefore must combine it with a Maternal Alpha Fetoprotein (MAFP) at 15-20 weeks gestation for detecting NTDs.
• Not as accurate as Integrated Prenatal Screening
• False positive rate: 5%

Maternal Serum Screening (MSS) AKA Triple screen

• What is it?The MSS is also known as a Triple Screen. If the Inhibin A is also tested, it is known as the Quadruple Screen(obviously because then 4 components will have been looked for). If Inhibin A is not done, it is known as a Triple Test (genius naming really!).
  It is composed of only a blood test with the following components:
1. B-hCG
2. Maternal Serum Alpha Fetoprotein (MSAFP):
3. Estriol (Unconjugated Estrogen)
4. Inhibin A
• When is it done? It is a 2nd trimester test done at 15-20 weeks gestation
• Advantages:
• 1 blood sample drawn only
• Can detect Trisomy 21 and 18 and NTDs
• Disadvantages:
• Late detection (in 2nd trimester), so no chance of offering chorionic villus sampling.

Integrated Prenatal Screening

• What is it?It is the combination of both tests: the MSS + FTS
  So an U/S is done in the first semester along with a blood test AND a blood test in the second semester looking for the respective components mentioned above in each test.
• When is it done?At the respective timings of the MSS and FTS
• Advantages:
• Most accurate screening schedule
• False positive rate: 2%
• Can detect Trisomy 21 and 18 and NTDs
• Disadvantages:
• 2 blood samples to be drawn
• Late detection (in 2nd trimester), so no chance of offering chorionic villus sampling.

Integrated Serum Screening

• What is it? It is the combination of ONLY the blood tests from the FTS and MSS (again the naming geniusly indicates this)
• When is it done? At the respective timings of the MSS and FTS

2nd Trimester U/S

• What is it?
  U/S scan done to look for fetal anomalies, fetal growth, location of placenta and number of fetuses (also for gestational age if no prior U/S done)
• When is it done? It is a 2nd trimester scan done at 18-20 weeks of gestation

Abnormalities in Screening tests

FTS
Down Syndrome (Trisomy 21): 

• Nuchal translucency: increased
• B-hCG: increased
• PAPP-A: decreased

MSS

Open Neural Tube Defects:

• MSAFP: increase
• B-hCG: normal
• Unconjugated estrogen (estriol): normal
• Inhibin A: normal

Down Syndrome (Trisomy 21):

• MSAFP: decreased
• B-hCG: increased
• Unconjugated estrogen (estriol): decreased
• Inhibin A: increased

Edward Syndrome (Trisomy 18):

• MSAFP: decreased
• B-hCG: decreased
• Unconjugated estrogen (estriol): decreased
• Inhibin A: normal

References:

1. ACOG practice bulletin no. 77: screening for fetal chromosomal abnormalities.

2. Essential Med Notes 2015: Obstetrics - Table 3, OB6

Year 1: Second Semester - Musculoskeletal Course

Books:

For all those puzzled year 1 souls who asked me:

1. Anatomy: (I've listed the best books most of my colleagues and I have discovered are the best for anatomy. Teachers for some reason cannot understand a student's perspective and recommend books such as Moore's or Snell's Anatomy. They are good but not as great as these ones for student understanding. These books illustrate perfectly in a student-friendly manner everything you need to know.)
1. Reference: Gray's Anatomy for Students
2. Atlas: Gray's Atlas of Anatomy
3. Atlas: Netter's Atlas of Human Anatomy by Frank H. Netter
4. Supplement: Clinical Anatomy by Systems - by Richard S. Snell
2. Pathology: 
1. Reference: Robbins Basic Pathology
2. Robbins & Cotran Pathologic Basis of Disease: this is the more comprehensive version of the above. Use it to better understand concepts in pathology that were not easy or were very concise for comprehension from the above one.
3. Rapid Review Pathology - by Edward F. Goljan: Great for reviewing just before TBLs or exams after you have studied a reference book such as Robbins.
4. Fundamentals of Pathology - by Husain A. Sattar (pathoma.com): also a great review.
3. Physiology:
1. Still haven't found a great physiology book that I recommend. 
2. Anatomy & Physiology: The Unity of Form & Function
3. Guyton & Hall Textbook of Medical Physiology: This is recommended by teachers and is too detailed for students. Some topics in this book are useful however. 
4. Physiology - by Linda S. Costanza: I've read the Board Review Series version of this and as it was a review book, it was not comprehensive enough for understanding. However, this does not seem to be a review book.
5. Human Physiology: An Integrated Approach
4. Pharmacology:
1. Supplement book: Katzung & Trevor's Pharmacology Examination & Board Review
5. Microbiology: (Read the post about the best microbiology books for med school)
1. Clinical Microbiology Made Ridiculously Simple
2. Microbiology - Lippincott Illustrated Reviews Series
6. Biochemistry:
1. Biochemistry - Lippincott Illustrated Reviews Series

How You Can Study:

• How can I study anatomy?
• This course is all about anatomy. Study the lectures as soon as they are given. An even better strategy is to study them before the class so as not to be lost. Then study them again after class. Why? You've just repeated the same material 3 times, which is needed in the musculoskeletal system for familiarizing yourself with the new vocabulary and memorizing it.

• To better understand and ingrain anatomy in your memory, you should try drawing them to understand. Even if it's rough-kindergarten drawings. You'll have a better feel of how the body works.
• Draw: if you have a talent/hobby for drawing/painting/art, then find ways to use that to your advantage. Anatomists long ago were not doctors, they were painters. To paint an accurate human body, they studied anatomy. (You might get to hang it up in university or the anatomy lab if the teacher loves your work!)
• Get or make flashcards for anatomy. Put them on your fridge, beside you bed, in the bathroom, in the living room. Everywhere in the house. Whenever you pass by, pick up a card and read it or try to remember its answer. This is something you can use for the rest of your study career (yes studying for medicine is a career and not a transitional phase).

• How can I study everything else?
• If there is one Golden Advice I would give you: don't study just for the semester. Study to ingrain things in your understanding and memory because in a bit of time when you are struggling in the clinical years, you won't have time to go back & study the basics along with the clinical sciences. This is especially true if you are intending on doing International Board exams (such as USMLE, MCCEE/QE, PLAB, even if the exams may not test basic medical sciences, you will require this in-depth basic knowledge to answer the clinical questions.)
• Pharmacology: attend the lectures and take notes, reading the notes with the presentation should be comprehensive enough. Read the book for topics you don't understand still.
• Microbiology: very little microbiology is taught in year 1. The teacher's reference books are Patrick Murray's Medical Microbiology and Cedric Mims' Medical Microbiology. These are both too detailed for a medical student. You can read them, however, for a deeper understanding of particular topics. 
• Biochemistry: The teacher's notes and lectures should be enough. If you don't understand a topic, Lippincott's book is great for biochemistry. It is concise and comprehensive for medical students. 

Student Notes: Introduction

Student Notes are notes I've written over the years to help me prepare a mental checklist of objects I should cover during Direct Observation Clinical Encounter Examinations (DOCEE). 

Naturally, any test in life that involves 2 examiners giving you "killing looks" (to quote Joe & Gus in Gone Fishin') while you take the history from a real patient and examine him/her, is bound to be stressful. Add to that, a grilling Q&A after you've finished examining the patient on your findings, differential diagnosis and management, and you're nerves are on fire for the next hour. 

So after my first DOCEE, I realized logic and common sense flew out the window the moment I entered a patient's room and saw 2 consultants peering at me. 

Therefore I devised a devious plan to overthrow their looks and score great on a DOCEE. 

Examiners tend to be strict in grading if cases are common and lenient when you are examined on a rare case.
Since this exam is conducted at hospitals, cases seen are most likely to be the common cases you encounter on a daily basis in your rotations. If you can at least get a mental checklist of those, that's a few cases less to worry about in the exams.

I'll be posting these throughout the year.

I hope you benefit from them!