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1. Prion includes: (AIIMS Nov 2007)
- DNA and RNA
- Only RNA
- Proteins
- Only DNA
ANSWER c
- Prions are infectious proteins that cause degeneration of the central nervous system (CNS).
- Prion diseases are disorders of protein conformation, the most common of which in humans is called Creutzfeldt-Jakob disease (CJD).
- In mammals, prions reproduce by binding to the normal, cellular isoform of the prion protein (PrPC) and stimulatingconversion of PrPC into the disease-causing isoform (PrPSc).
- PrPC is rich in alpha-helix and has little beta-structure, while PrPSc has less alpha-helix and a high amount of beta-structure. This alpha-to-beta structural transition in the prion protein (PrP) is the fundamental event underlying prion diseases.
- Prions are the only known infectious pathogens that are devoid of nucleic acid; all other infectious agents possess genomes composed of either RNA or DNA that direct the synthesis of their progeny.
- Prion diseases may be manifest as infectious, genetic, and sporadic disorders.
- The sporadic form of CJD is the most common prion disorder in humans.
- Familial CJD (fCJD), Gerstmann-StrausslerScheinker (GSS) disease, and fatal familial insomnia (FFI) are all dominantly inherited prion diseases that are caused by mutations in the PrP gene.
- Although infectious prion diseases account for <1% of all cases and infection does not seem to play an important role in the natural history of these illnesses, the transmissibility of prions is an important biologic feature.
- Kuru is an infectious prion disease thought to have resulted from the consumption of brains from dead relatives during ritualistic cannibalism in New Guinea.
- A major feature that distinguishes prions from viruses is the finding that both PrP isoforms are encoded by a chromosomal gene.
- In humans, the PrP gene is designated PRNP and is located on the short arm of chromosome 20.
- Accidental transmission of CJD to humans appears to have occurred with corneal transplantation, contaminated electroencephalogram (EEG) electrode implantation, surgical procedures, implantation of dura mater grafts and from contaminated human growth hormone preparations.
2. Pathologic features of brain in AIDS are all, except: (AIIMS Nov 2001)
- Perivascular giant cell invasion
- Microglial nodules
- Vasculitis
- Temporal lobe infarction
ANSWER c
Anderson clearly mentioned that “Unlike most other encephalitides, HIV does not seem to infect neurons and perivasculitis is conspicuously absent”
“Characteristic multinuclear Giant Cells of Macrophage origin are seen in white matter of frontal and temporal lobes particularly in perivascular location”
Feature of CNS involvement in AIDS
- Diffuse and focal spongiform changes
- Vacuolar myelopathy of posterior column of spinal cord
- Major cells affected are macrophages and monocytes
- Most characteristics finding is chronic inflammatory reaction with widely distributed infiltrates of microglial nodules
3. Commonest cause of cerebral infarction is:
- Arterial thrombosis
- Arteritis
- Venous thrombosis
- Embolism
ANSWER a
4. Albumino-cytologic dissociation occurs in cases of:
- Guillain Barre syndrome
- TB meningitis
- Motor neuron disease
- Demyelinating disorder
ANSWER a
A rare disorder in which your body's immune system attacks your nerves.
Guillain-Barré syndrome (GBS) is a rare condition in which a person’s immune system attacks the peripheral nerves.
People of all ages can be affected, but it is more common in adults and in males.
Most people recover fully from even the most severe cases of Guillain-Barré syndrome.
Weakness and tingling in your hands and feet are usually the first symptoms. These sensations can quickly spread, eventually paralyzing your whole body.
The exact cause of Guillain-Barre syndrome is unknown.
Signs and symptoms of Guillain-Barre syndrome may include:
- A pins and needles sensation in your fingers, toes, ankles or wrists
- Weakness in your legs that spreads to your upper body
- Unsteady walking or inability to walk or climb stairs
- Difficulty with facial movements, including speaking, chewing or swallowing
- Double vision or inability to move the eyes
- Severe pain that may feel achy, shooting or cramplike and may be worse at night
- Difficulty with bladder control or bowel function
- Rapid heart rate
- Low or high blood pressure
- Difficulty breathing
5. Most common type of pathological changes seen in Rabies are:
- Meningitis
- Cranial arteritis
- Ventriculitis
- Brain stem encephalitis
ANSWER d
Rabies is a fatal but preventable viral disease. It can spread to people and pets if they are bitten or scratched by a rabid animal.
Initial symptoms of rabies are nonspecific: fever, headache, and malaise. Within days, encephalitis (furious rabies; in 80%) or paralysis (dumb rabies; in 20%) develops. Encephalitis causes restlessness, confusion, agitation, bizarre behavior, hallucinations, and insomnia.
