Mixed / Miscellaneous Topics MCQs

The major toxins used for strain classification of clostridium perfringens are alpha toxin, beta toxin, epsilon toxin, and iota toxin. Alfa toxin is responsible for hemolysis, myonecrosis and gas gangrene in the infected tissue. Reference- Microbiology by Ananthanarayan and Paniker, 8th ed. pg. 251, 263, 634

PATHOPHYSIOLOGY OF DISK DEGENERATION: Loss of Proteoglycan - The aggrecan molecules become smaller and get leached from the tissue. This reduces glycosaminoglycans and water holding capacity and thus there is fall in the osmotic pressure of the disk matrix. Loss of Collagen Fibers - Type II collagen become more denatured and get replaced by type 1 collagen. Increase in Fibronectin - Fibronectin content increases with increasing degeneration and it becomes more fragmented. Enzymatic Activity - Increased fragmentation of the collagen, proteoglycan and fibronectin is mediated by increased enzymatic activity including cathepsins, MMPs and aggrecanases. Reference: Manish Kumar Varshney, 1 st edition, Page no. 1353.

SPINAL CORD: The spinal cord extends from the level of foramen magnum to the level of the intervertebral disc between 1st and 2nd lumbar vertebra. The spinal cord is 40-50 cm long and 1-1.5 cm in diameter. By weight the spinal cord contributes only 2% of the central nervous system. All the three meninges namely the pia, arachnoid and dura mater cover the spinal cord. It is attached to the dura mater by a series of lateral denticulate ligaments emanating from the pial folds. Reference: Manish Kumar Varshney, 1 st edition, Page no. 1331.

Ans. is 'b' i.e., HIV encephalitis o Perivascular infiltrate of lymphocytes (and macrophages) with microglial nodules is seen in HIV encephalitis. o Perivascular infiltrate of lymphocytes (and monocytes) is also seen in multiple sclerosis. But, microglial nodules are characteristic of HIV encephalitis.