USMLE Step 1: Biochemistry & other

extracellular deposits of amyloid formed by calcitonin secreted from neoplastic parafollicular c-cells

• a neuron responding to an irreversible injury
• 12-24h after injury:
  • cell body shrinkage
  • eosinophilia of cytoplasma
  • pyknosis of the nucleus
  • loss of Nissl substance

• arsenic, thorotrast, polyvinyl chloride
• tumor cells express CD31 (endothelial cell marker)

1. at birth
2. 40-50y

quite specific for CF

Insulin

Bronchogenic Ca followed by mesothelioma

presents in childhood with recurrent episodes of acute pancreatitis

G:C –> T:A transversion in codon 249 of the p53 gene –> increased risk HCC

most common cardiac abormality predisposing to native vavle bacterial endocarditis

• subacute, combined degeneration of the posterior & lateral spinal columns
• Diagnosis of Vit B12 deficiency: increased serum level of methylmalonic acid

Cerebral amyloid angiopathy

• bacterial endocarditis
  • acute diffuse, proliferative glomerulonephritis secondary to circulating immune complexes –> can result in acute renal failure

N. laryngeus recurrens sinister

• occurs in children with febrile illness treated with aspirin
• hepatic failure + encephalopathy
• histologic: microvesicular steatosis of hepatocytes without inflammation, and cerebral edema

1. epithelial origin
2. B-lymphocytes
3. T-lymphocytes
4. Myeloid cells
5. mesenchymal origin
6. neuroendocrine tumors

• 185 kD transmembrane glycoprotein
• has intracellular tyrosine kinase activity –> accelerates cell proliferation
• increases the risk of breast & ovarian cancer

• in sickle cell disease
• in case of hemolysis, haptoglobin levels decrease by binding to free hemoglobin, and the complex is hepatically cleared

activating mutation of FGF receptor-3

• within plaques: loss of myelin sheaths & depletion of oligodendrocytes
• cerebrospinal fluid: oligoclonal bands of IgG may be detected
• oligodendrocyte depletion is also senn in progressive multifocal leukencephalopathy

paradoxical rise in jugular venous pressure on inspiration –> indicative of limited right ventricular filling due to right heart failure

• ataxic gait
• urinary incontinence
• dementia
• symptoms are explained by distortion of periventricular white matter
• is a communicating hydrocephalus
• occurs due to a diminished reabsorptive capacity of the arachnoid villi

• severe, episodic, unilateral periorbital & temporal oain associated with lacrimation, nasal congestion & ptosis
• usually occur at same time each day
• more common in males

• semental thrombosing vasculitis –> extends into contiguous veins & nerves, encasing them in fibrous tissue
• heavy smokers with onset before 35
• associated with hypersensitivity to intradermal injections of tobacco extracts

• early: dilated pupil & loss of accomodation
• late: ptosis & ophthalmoplegia

• "down & out" position
• normal-sized, reactive pupil
• ptosis

activated macrophages –> extrarenal formation of 1,25-dihydroxy vit D

• hemorrhagic disease
• need supplemation of Vit K

Alzheimer's

• anti-CD3
• useful in treatment of acute rejection in patients with kidney, heart & liver transplants

ability of modifying their outer membrane proteins by the process of antigenic variation

• produced by macrophages
• induces chemotaxis & phagocytosis in neutrophils

• eczema
• thrombocytopenia
• combined B- & T-lymphocyte deficiency
• typical:
  • onset early in life:
    • thrombocytopenia at birth
    • eczema & repeated infections (particularly by encapsulated organisms) following at 6-12 months of age

produced by TH₂ –> facilitates growth of B-cells & TH₂-lymphocytes and stimulates antibody isotype switching, particularly to IgE