Structure of Heme Heme is a ferro-proto-porphyrin. Heme = Protoporphyrin IX ring + Iron (Fe) in center Protoporphyrin IX = porphyrin with attachment to 4 Methyl, 2 Propionyl and 2 Vinyl groups. Porphyrin = Cyclic structure with 4 pyrrole rings Pyrrole rings are derived from Porphobilinogen (PBG) Hydroxymethylbilane = Linear…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Ischemic Heart Disease Pathophysiology
Definitions of Related Terms A) Ischemic Heart Disease (IHD): It is the imbalance between myocardial oxygen supply and demand, resulting in myocardial hypoxia and accumulation of waste metabolites. The components of IHD are: Stable Angina Acute Coronary Syndrome (ACS) B) Stable Angina: Pattern of chronic, predictable, transient chest discomfort during…
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Medical Humanities in Nepal
The practice of medicine is an art, not a trade; a calling, not a business; a calling in which your heart will be exercised equally with your head. – Mark E Silverman Shapiro et.al. defined medical humanities with characteristic features: Use of methods, concepts, and content from one or more…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Cholesterol Synthesis Mnemonic
Liver as a hub of cholesterol metabolism All nucleated cells have the capacity to synthesize cholesterol from acetyl-CoA (like most biological lipids). 90% of synthesis occurs in liver and intestine. The cholesterol biosynthesis pathway involves enzymes that are in the cytoplasm, microsomes (ER), and peroxisomes. Liver obtains cholesterol from 3…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Lipoprotein Metabolism Simplified
Lipoproteins Composition of Lipoproteins: Non-polar core – mainly triglycerides and cholesteryl esters Single surface layer – amphipathic phospholipids and cholesterol Apoprotein or Apolipoprotein Class Abbreviation Density Protein Lipid content Electrophoretic mobility Chylomicrons CM lowest lowest highest (exogenous triacylglycerol) don’t migrate Very low density lipoproteins VLDL .. .. .. (endogenous triacylglycerol)…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Neutropenic Fever and Empiric Therapy
Synonym: Febrile Neutropenia Definition of Neutropenic Fever Fever: Single oral temperature ≥ 38.3 °c (101 °F) or ≥ 38 °c (100.4 °F) sustained over 1 hour Neutropenia: Absolute Neutrophil Count (ANC) <500 cells/cu.mm or ANC expected to fall <500/cu.mm in next 48 hours Profound neutropenia: ANC <100/cu.mm Prolonged neutropenia: Neutropenia for >7 days…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Bronchogenic Carcinoma Etiopathogenesis
INCIDENCE Male > Female Age group: 50-75 years Second highest cancer in both sexes after prostate (male) and breast (female) Smokers > Non-smokers ETIOLOGY OF LUNG CANCER A. Cigarette smoking: Smoking is the single most important risk factor for lung cancer, which can cause all types of lung cancer but…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Inheritance of Disease – Mnemonics
Lets work with some generalizations 1. X-linked dominant, mitochondrial and Y-linked conditions are rare. You need to remember them. 2. Usually inherited in autosomal dominant pattern are: Mostly mutations in non-enzymatic structural proteins (e.g. collagen, fibrillin, cytoskeletal proteins of RBC) or in membrane receptors (e.g. LDL receptor) Diseases due to diminished…