Following statements are regarding to enzymatic processing of benzo(a)pyrene to a more potent mutagen and carcinogen.

A. Liver enzymes, particularly P-450 enzymes, modify benzo(a)pyrene in a series of reactions, producing 7,8-diol-9,10-epoxide, a highly potent mutagenic species that reacts with DNA primarily at the N2 atom of a guanine base.

B. The adduct, (+)-trans-anti-B(a)P-N2-dG, causes polymerase to insert an A rather than a C opposite the modified G base. Next time the DNA is replicated, a T will be inserted opposite the A, and the mutation will be complete.

C. Potent mutagen majorly causes conversion of guanine (G) to thymine (T) bases, a transition mutation.

D. When this potent mutagen applied to cultured bronchial epithelial cells, activated benzo(a)pyrene induces many mutations, including activating mutations at codons 175, 248, and 273 of the p53 gene.

Which of the following statements are correct?

TLS Online TPP Program

#Question id: 12216

#Unit 7. System Physiology – Animal

Gastric emptying is regulated to ensure the chyme enters the duodenum at an appropriate rate. Which of the following factors promotes gastric emptying?

TLS Online TPP Program

#Question id: 12215

#Unit 7. System Physiology – Animal

Damage to the gastric mucosal barrier is a forerunner of gastric ulcer. Which of the following can both damage the gastric mucosal barrier and stimulate gastric acid secretion?

TLS Online TPP Program

#Question id: 12214

#Unit 7. System Physiology – Animal

A 53-year-old man with a recurrent history of ulcer disease associated with diarrhea and a strong family history of duodenal ulcer disease is suspected of having Zollinger-Ellison syndrome (gastrinoma). Secretin (2 units/kg) was given as a rapid intravenous injection to test for gastrinoma. Which of the following results would support the existence of gastrinoma following secretin administration?

TLS Online TPP Program

#Question id: 12213

#Unit 7. System Physiology – Animal

The gastric phase of gastric secretion accounts for about 60% of the acid response to a meal. Which of the following can virtually eliminate the secretion of acid during the gastric phase?

TLS Online TPP Program

#Question id: 12212

#Unit 7. System Physiology – Animal

 A 71-year-old man with upper abdominal pain and blood in the stool takes NSAIDS for the pain and washes it down with whiskey. Pentagastrin administration produced lower than predicted levels of gastric acid secretion. Secretion of which of the following substances is most likely to be diminished in this patient with gastritis?

TLS Online TPP Program

#Question id: 12211

#Unit 7. System Physiology – Animal

A 57-year-old man is admitted as an emergency for upper GI bleeding. Endoscopy reveals multiple ulcers in the duodenum. Serum gastrin levels are eight-fold higher compared to normal. Zollinger-Ellison syndrome (ZES, gastrinoma) is suspected. Administration of which of the following substances is useful in confirming the diagnosis?