A couple seeks genetic counseling following the recent diagnosis of cystic fibrosis in their youngest child. Their two older children are healthy and have normal sweat chloride test results. Which of the following is the likelihood that each of the unaffected children is a carrier of cystic fibrosis?

 A previously healthy 42-year-old man has had postprandial epigastric pain over the past 2 weeks. In the past 24 hours he has passed 3 maroon-colored stools. Endoscopy shows a 2-cm diameter antral ulcer. Examination of the ulcer tissue obtained on biopsy shows the presence of Helicobacter pylori. This organism is able to survive in the stomach in part because it secretes which of the following substances?

A 45-year-old woman has increased blood pressure, decreased urine output, and an increased serum creatinine concentration 9 weeks after renal allograft transplantation. Which of the following elements of the patient's immune system are most likely responsible for these clinical changes?

A 24-year-old woman is admitted to the hospital because of a temperature of 40°C (1047), generalized rash, and altered mental status, On admission, her platelet count, prothrornbin time (PT), and activated partial thromboplastin time (aPTT) are within the reference ranges. During the next 24 hours, her blood and cerebrospinal fluid cultures grow Aleisseria meningitidis. Despite therapy, she becomes comatose and begins bleeding from all venipuncture sites and from mucous membranes. Her PT and aPTT are now markedlyprolonged: and platelet count is less than 20,000imm3. Which of the following plasma values is most likely to be increased in this patient?

A 40-year-old woman comes to the physician because of a 1-year history of chronic low back pain, Exercises to strengthen the abdominal muscles are recommended. Straight-leg raising consists of raising both lower extremities while lying flat on her back. Which of the following muscles is most directly involved in this exercise?