CTBS Tissue Processing & Preservation 5

Question 1

What is the functional difference between 'fresh' and 'fresh-frozen' allograft bone regarding osteoinductivity?

Accepted Answer

Fresh bone retains more viable cells and growth factors; fresh-frozen loses some bioactivity but retains structural properties

Answer

Fresh bone retains living osteoblasts and higher concentrations of growth factors, while freezing partially denatures proteins and kills cells though structural integrity is largely preserved.

Question 2

A processing technician inadvertently leaves a skin allograft at 4°C for 72 hours in nutrient media. Which microorganism is of GREATEST concern regarding overgrowth during this period?

Accepted Answer

Pseudomonas aeruginosa

Answer

Pseudomonas aeruginosa is a psychrotolerant gram-negative bacterium that can proliferate at refrigerator temperatures, posing the greatest risk during prolonged cold storage.

Question 3

Which statement BEST describes the role of sucrose in cardiac valve cryopreservation media?

Accepted Answer

It acts as an extracellular impermeant to reduce osmotic cell swelling

Answer

Sucrose is a large molecule that does not cross cell membranes; it raises extracellular osmolality to counteract osmotic swelling caused by cryoprotectant-induced cell shrinkage.

Question 4

Which processing step is UNIQUE to the preparation of demineralized bone matrix (DBM) compared to standard cortical bone processing?

Accepted Answer

Acid demineralization (typically in 0.5N HCl)

Answer

DBM production requires an acid demineralization step (commonly 0.5N HCl) to dissolve the mineral hydroxyapatite and expose the collagen and growth factor matrix.

Question 5

In tissue banking, what is the significance of the 'D-value' (decimal reduction value) when validating a sterilization process?

Accepted Answer

The time or dose required to reduce the microbial population by 90% (one log)

Answer

The D-value represents the time or dose needed to kill 90% of a test organism population under defined conditions, forming the basis for sterilization cycle validation.

(CTBS) Certified Tissue Bank Specialist Practice Test

(CTBS) Certified Tissue Bank Specialist Practice Test

CTBS Tissue Processing & Preservation 5