1
Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : In ruminants, photosensitization is a cascading reaction in which a photodynamic molecule gets activated by
the absorption of an appropriate wavelength leading to clinical photosensitization
Reason (R) : It is usually due to the pouring of phylloerythrin in the dermal blood circulation, secondary to diffuse liver
disease.
In light of the above statements, choose the correct answer from the options given below.
EXPLANATION
General Principles of Toxicology
- Pathogenesis of Secondary Photosensitization:
- Assertion (A): Photosensitization is a photodynamic reaction wherein an absorbing molecule in cutaneous capillaries is activated by UV/sunlight ($320 - 400\text{ nm}$), producing reactive oxygen species that induce severe cutaneous necrosis and dermatitis. (True).
- Reason (R): In ruminants, Phylloerythrin is a porphyrin breakdown product of chlorophyll produced by rumen microbes and normally excreted in bile. Diffuse liver injury (facial eczema from sporidesmin, lantana toxicity, pyrrolizidine alkaloids) impairs biliary excretion, causing phylloerythrin to spill into dermal blood circulation where sunlight activates it. (True).
- nalysis:
- Both (A) and (R) are true, and (R) is the precise physiological cause of (A). Hence, Option 1 is correct.
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