64-year-old man presents with a tremor in his legs and arms. He says he has had the tremor for "many years", but it has worsened in the last year. The tremor is more prominent at rest and nearly disappears on movement. His daughter mentions that his movements have become slower. The patient is afebrile and vital signs are within normal limits. On physical examination, the patient is hunched over and his face is expressionless throughout examination. There is a "pillrolling" resting tremor that is accentuated when the patient is asked to clench the contralateral hand and alleviated by finger nose testing. When asked to walk across the room, the patient has difficulty taking the first step, has a stooped posture and takes short rapid shuffling steps. A doctor initiates pharmacotherapy and the drug of first line, levodopa, is prescribed. Which of the following is the most likely mechanism of action of this drug?

A 43-year-old man seeks evaluation at emergency department with complaints of fever with chills, melaise, diffuse abdominal pain for over a week, diarrhea and loss of appetite. He says that his symptoms are progressively getting worse. He recalls that the fever began slowly and climbed its way- up stepwise to the current 39.8°C. His blood pressure is 110/70 mm Hg. A physical exam reveals a coated tongue, enlarged spleen and rose spots on the abdomen. Serologic study shows the agglutinin O titre of 1:200 by the Widal test. Which of the following is the most likely causative organism for this patient's condition?

A 34-year-old-man visits dentist complaining of toothache. After a dental procedure that onvolved extraction of several teeth, he develops severe bleeding lasting more than 15 minutes. He has a history of chronic hepatitis. Which of the following is the most likely cause of prolonged bleeding in this patient?

60-year old man with a history of hypertension, diabetes and hyperlipidemia had a sudden onset a right-sided weakness. By the time the ambulance arrived, he had difficulty speaking. Unfortunately, the patient died within the next two hours and an autopsy was performed immediately. The gross examination of the cerebral left hemisphere showed brain swelling, widened, gyri and poorly demarcated gray-white junction. Which of the following is the most likely cause of this patient`s death?

A 37-year-old man is admitted to hospital with mental confusion and disorientation. His wile reports

he became more irritable and forgetlul in the past year. In addition, she notes that be became a vegan

a year ago and currently, his diet consists of starchy foods like potatoes, corn and leafy vegetables.

GI symptoms include anorexia, diarrhea and vomiting. He has glossitis and skin lesions that appear

as vesicles over the extremities. Eczemalike lesions around the mouth, as well as desquamation and

roughened skin over the hands are also present. Neurologic examination reveals symmetrical

hypesthesia for all types of sensation in both upper and lower extremities in a ’’gloves and socks”

distribution. Deficiency in diet of which of the following amino acids is the most likely cause of this

condition?

A group of researchers aimed to study cardiac physiology found that overstretching of atria in the heart leads to decreased sodium reabsorption in the distal convoluted tubule and increase in glomerular filtration rate. Which of the following is the most likely cause ot physiologic effects discovered by researchers?

14-year old girl presents to the emergency department for evaluation of an "infected leg". She states there is no history of trauma but mentions she had a history of sickle cell disease. On physical examination, her upper part of right shin is very painful, red, swollen and hot. Her temperature is 39.2°C. An X-ray shows focal bony lysis and loss of trabecular architecture in the metaphysis of right tibia, increased activity of which of the following cells is the most likely cause of bone reabsorption in this patient?

A male neonate born to a 24-year-old primigravida had jaundice at 8 hours f life The neonates red

blood cell time was A+, while the mothers RBC type was 0+. Laboratory studies revealed elevated

titer of mother's anti-A antibody, normal erythrocyte glucose-6-phosphate and negative sickle cell

test. The infant’s hemoglobin was 106 g/L. Which of the following is the most likely cause of infant’s

jaundice?

A 20-year-old female comes to the clinic after missing her last 2 periods. Her cycles are usually regular, occurring at 28-30 day interval with moderate bleeding and some abdominal discomfort. She also complains of progressively diminishing peripheral vision. Her doctor reveals loss of vision in the lateral halves of both eyes. Involvement of which of the following structures would you most likely expect to be the reason of bitemporal hemianopsia?