Usmle World Notes

USMLE World Notes - Important Points

**Credits to Duncan

• Subendothelial Deposits are seen in SLE patients

• Subepithelial Humps are seen in Acute Poststreptococcal Glomeruloneprhitis

• Linear Subendothelial are seen in Goodpasture’s (Type II)

• Mesangial Deposits are seen in IgA Nephropathy

• Spike and Dome are seen in Membranous

• Subendothelial Humps are seen in Membranoproliferative

• Azithromycin – administered to HIV + patients can prevent Mycobacterium Avium

• Ethambutol – inhibits arabinosyl transferase which polymerizes arabinose into arabinan etc. Side Effects à Optic Neuritis

• Rifampin – inhibits bacterial DNA dependent RNA polymerase and thus prevents transcription of DNA into mRNA.

• Isoniazid – inhibits mycolic acid synthesis.

• FF = GFR/RPF GFR = Creatinine Clearance/Inulin

• RPF = PAH

• Fibroadenoma – cellular myxoid stroma, sometimes there are compressed cystic spaces.

• Spongiosis - epidermal accumulation of edematous fluid in the intercellular spaces.

• Diphenoxylate – opiate anti-diarrheal structurally related to Meperidine.

• Octreotide – good for secretory diarrhea, which is a Somatostatin Analog

• Urease – converts urea to carbon dioxide and ammonia and thus increases pH

• Radiation Therapy - causes 1) DNA double strand breakage 2) formation of free radical

• Methadone – has a long half life

• In Fetal Lungs - after 30 weeks there is an increase in Lecithin

• After 36 weeks there is a rise in Phosphatydylglycerol

• Males with 5 α reductase deficiency - feminized external genitalia, small phallus and Hypospadias are common.

• Repair Damage – Glycosylase à Endonuclease à Lyase à DNA Polymerase à Ligase

• H. Pylori – most common cause of duodenal ulcers

• CMV in immunocompromised – Mononucleosis

• Retinitis in CMV – HIV+ Patients

• Primary CNS Lymphoma – most commonly associated with AIDS

• Squamous Cell Lung Cancer – produces Parathyroid Hormone Related Peptide, which in turn will decrease PTH

• Campylobacter – can be transmitted from domestic animals

• Shigella - is transmitted via fecal oral in day care centers

• Keratin - marker of epithelial cell origin.

• Secretin - produced by S endocrine cells in the duodenum, that increases bicarbonate secretion from exocrine pancreas into the small bowel.

• Alprazolam – benzodiazepine with the shortest half life, which is used in Acute Anxiety.

• Diazepam, Chlordiazepoxide and Clonazepam – longest half life, used in prophylaxis.

• Sheets of Primitive Cells with Many Mitotic Figures – Medulloblastoma

• Most Common Tumors in Children:

• Pilocytic Astrocytoma - Rosenthal Fibers

• Medulloblastoma - sheets of small blue cells, many mitotic figures

• Ependyoma – can cause Hydrocephalus and form Rosettes

• Orthostatic Hypotension – side effects of α adrenergic blockers.

• AML - has associations with t(15,17), t(8,21) and Auer Rods are stained with Myeloperoxidase.

• CLL – deletion on Chromosome 13

• Mantle Cell B Lymphoma – t(11,14)

• Dobutamine – causes increase in cardiac contractility and increase in Heart Rate

• Tumors of Schwann Cells – are derived from neural Crest Cells.

• Patients with CGD – susceptible to 1) Staph Aureus 2) Pseudomonas 3) Serratia

• Nocardia 5) Aspergillus

• Rosenthal Fibers – with granular eosinophilic bodies are seen in Pilocytic Astrocytoma. They are well differentiated comprised of spindle cells with hair like glial projections

• Atropine – reverses muscarinic effects but does not prevent the development of nicotinic effects such as muscle paralysis

• Pralidoxime – reverses both muscarinic and nicotinic effects of organophosphates by “restoring” cholinesterase.

• Calcium – binds to Troponin C and then uncovers tropomyosin sites, thus allowing actin to bind to myosin.

• S 3 Heart Sound – can be heard if the patient lies down in Left Lateral Decubitus Position or Exhales Completely

• RBF = Renal Plasma Flow/ (1-Hematocrit)

• In Metabolic Alkalosis – measure patient’s Urinary Chloride

• Germinoma - tumors of Pineal Gland, formed in children and adolescents.

• Will present with 1) Precocious Puberty due to β-HCG Production (similar in testicular seminoma) 2) Obstructive Hydrocephalus 3) Parinaud Syndrome – paralysis of upward gaze.

• Ultraviolet Specific Endonuclease – initiates repair by nicking the strand at Thymine Dimer. This enzyme is missing in Xeroderma Pigmentosum

• SER – functions in synthesis of Lipids, Carbohydrate Metabolism and Detoxification of Harmful Substances

• Uretero Pelvic Junction – most common site of obstruction

• Increased Intraocular Pressure – most common side effect of treatment of Bradycardia with Atropine.

• Mutation in Glycoprotein – will cause changes in the host and they mediate attachment to target host cell.

• cAMP pathway - α2, β1 and β2

• Inositol Pathway – α1 adrenergic, muscarinic, cholinergic

• Ion Channel – Nicotinic, Cholinergic.

• Ampicillin – must be added to treat infants with Meningitis. Ceftriaxone covers all organisms, but Listeria Monocytogenis is killed by Ampicillin.

• B 19 Fifth’s Disease – causes aplastic crises (bone marrow)

• Eaton Lambers Syndrome - associated with Lung Cancer, similar to Myasthenia Gravis. Antibodies are against pre-synaptic Calcium Channels.

• Myotonic Dystrophy – triplicate repeat, movement frontal baldness, cataracts are seen. Cannot Loosen Hand Grip.

• Cholinomimetics – indicated in Urinary Retention Paralytic Ileus and Glaucoma

• HUS – after E. Coli – Microangiopathic Hemolytic Anemia

• Segmental Viruses (Rotavirus and Orthomyxovirus) - capable

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