Immune System/Malignancies
Agammaglobulinemia, or hypogammaglobulinemia, is the most common of the primary immunodeficiencies, accounting for approximately 50% of cases. X-linked agammaglobulinemia (XLA) is a primary humoral immunodeficiency characterized by severe hypogammaglobulinemia, antibody deficiency, and increased susceptibility to infection within the first 18 months of age. Which of the following proteins is the one defective protein responsible for XLA?
Bruton's Tyrosine Kinase
Lecture #246
Which subfamily of cytochrome P-450s is responsible for the highest fraction of clinically important drug interactions resulting from metabolism?
CYP3A
Lecture #041
A patient presents with a hemolytic anemia due to a drug treatment. Which of the following would be a consequence of this disorder?
Higher percent of reticulocytes in the blood
Lecture #072
Which of the following correctly states what the transcription factor TFIID does during initiation of gene transcription in eukaryotic cells?
It recognizes and binds to multiple promoter elements
Lecture #009
What is the carcinogen produced by overcooking of meat, poultry, or fish at high temperatures?
Heterocyclic Aromatic Amines
Lecture #074
Which of the following are universal recipients who can receive blood from any donor, but can donate only to individuals with their blood type?
AB RhD+
Lecture #173
Upon pedigree analysis, a particular medical condition is found to be occurring in multiple generations of a family. Which of the following is the one feature that would be most helpful in determining if such a condition is likely to be X-linked dominant rather than autosomal dominant?
All daughters of affected males are affected.
Lecture #011
Hydroxyurea (a ribonucleotide reductase inhibitor) has been shown to decrease the frequency of sickle cell related pain due to vaso-occlusion and the incidence of acute chest syndrome. The mechanism of action is:
It induces fetal hemoglobin (HbF) production and thereby decreases the formation of intracellular HbS polymerization
Lecture #110
Certain amino acids are not part of the primary structure of proteins but are modified after translation. In scurvy, which of the following amino acids that is normally part of collagen cannot be hydroxylated after translation?
Proline
Lecture #057
Assume there is a microRNA that participates in down-regulating the expression of a particular cyclin kinase inhibitor. Which of the following would best explain how an alteration in this microRNA could lead to uncontrolled cell proliferation?
Overexpression of the microRNA, so its acts as an oncogene.
Lecture #061
A 7-year-old boy is brought to the hospital for the evaluation of upper respiratory tract infection with green colored sputum. He has a history of recurrent bacterial infections since childhood. The patient's temperature is 102 (38.8), and has a respiratory rate of 25 breaths/min. On physical examination, the patient has bluish discoloration of the skin. Laboratory values show decreased IgG, IgA, and IgE. Which of the following is the most likely mechanism to explain this patient's condition?
Defective CD40 ligand on T helper cells
Lecture #151
An 11-year-old male with a family history of tall stature, high-arched palates, long fingers, and sudden death in early adulthood or adolescence is being evaluated by a clinician. The parents are unsure of the exact diagnosis, but the patient's maternal uncle died suddenly. An autopsy of the uncle revealed the cause of death as aortic rupture secondary to an aortic aneurysm. What is the type of inheritance pattern seen in this pedigree?
Autosomal Dominant
Lecture #011
A 3-year-old boy presents with recurrent joint pain involving the knees and hips. He had always bruised easily, and recently the parents had seen blood in his urine. A presumptive diagnosis of classic hemophilia (hemophilia A) is made, and coagulation blood tests are performed. Which of the following is the most likely set of findings of coagulation screening tests?
Normal bleeding time, platelet count, thrombin time, and PT; prolonged APTT
POPS #141
A woman returns from a year-long trip abroad with her 2-week-old infant, whom she is breastfeeding. The child soon starts to exhibit lethargy, diarrhea, vomiting, jaundice, and an enlarged liver. The pediatrician prescribed a switch from breast milk to infant formula containing sucrose as the sole carbohydrate. The baby's symptoms resolve within a few days. Which of the following was the most likely diagnosis?
Galactosemia
Lecture #057
A 57-year-old man, who had worked for three decades in a chemical factory where polycyclic aromatic hydrocarbons (PAHs) were produced, developed a lung mass which was found to be an adenocarcinoma. Primary carcinogens such as benzopyrene are involved in carcinogenesis based on their ability to:
Produce DNA base alterations
Lecture #074
A 65-year-old woman presents to the clinic with cough, fever, vomiting, and fatigue for the past three days. A respiratory panel is done and is positive for the influenza virus. Proteins such as MHC2 and MHC1 are usually found on professional antigen-presenting cells and are essential in initiating immune responses. In the present case, which of the following T cell surface molecules is a binding partner to the MHC protein on antigen presenting cells such that effective antigen presentation can occur?
CD8+ Cytotoxic T Cells
Lecture #255
A 27-year-old woman presents for a pregnancy test. She recalls drinking heavily during the week in which she may have conceived. What is the most likely consequence of toxic exposure to the conceptus during early (preimplantation) development?
Embryonic Lethality
Lecture #108
A 26 year old woman complains of the acute onset of anuria, purpura, and mental confusion. Her peripheral blood film displays marked thrombocytopenia and abundant schistocytes. Laboratory studies reveal elevations of bilirubin, creatinine, and lactose dehydrogenase. A skin biopsy shows numerous intravascular thrombi within the dermal microvasculature. What is the most likely diagnosis?
Thrombotic Thrombocytopenia Purpura
Lecture #111
A 17-year-old boy with type 1 diabetes mellitus is brought to the emergency department after being found drowsy and incoherent. He went to visit his family over the weekend and forgot to bring his insulin. On examination, the patient appears lethargic and is breathing rapidly. Blood glucose is 330 mg/dL (65-110), and urinalysis shows 4+ ketones. Which of the following findings would most likely appear on this patient's arterial blood gas analysis?
Metabolic acidosis with respiratory compensation
PBL #039 Ms. Vera
A 45 year-old man is diagnosed with cancer of the proximal portion of the colon. His father died of colon cancer at the age of 52. He has three siblings. His 55 year-old brother has not been diagnosed with cancer, but his 57 year-old sister has an endometrial carcinoma, and his other sister died of ovarian cancer. Which of the following types of mutations most likely occurred in this family?
Mutation(s) causing defects in the mismatch repair system
PBL (MK) #064 and #140 ದ?Mr. Palter.
Compare and Contrast B cell development from T Cell development.
B cells undergo just negative selection while T cells undergo positive and negative selection during development.
Lecture #246/248
An 8-month-old infant is brought to his pediatrician because he has had difficulty in feeding and frequently vomits following feedings. The parents indicate that their son had been able to sit by himself but now is incapable of doing so. Upon examination the doctor notes that the infant has obvious hepatosplenomegaly and is emaciated. Additional physical signs include thin limbs. Examination of his eyes reveals a cherry-red spot in the central part of the retina. Analysis of monocytes indicates the presence of sphingomyelin-rich lipids. The clinical findings in this infant indicate he is suffering from which of the following disorders?
Niemann-Pick disease type A1
Lecture #037
A family has two children, one with a mild case of thalassemia and a second with a severe case of thalassemia, requiring frequent blood transfusions as part of the treatment plan. One parent is of Mediterranean descent, the other is of Asian descent. Neither parent exhibits clinical signs of thalassemia. Both children express 20% of the expected levels of ȕ?globin; the more severely affected child expresses normal levels of a Į?globin, whereas the less severely affected child expresses only 50% of the normal levels of Į?globin. Why is the child who has a deficiency in Į?globin expression less severely affected?
The more severely affected child produces more alpha globin chains than the less severely affected child resulting in precipitation of the alpha globin and damage to the membrane
Lecture #110
A 15-year-old boy presents with confusion, lethargy, and abdominal pain. The patient's past medical history includes type I diabetes mellitus. According to his mother, the patient has had a sore throat and low-grade fever for the past few days. Vital signs show oxygen saturation 98% on room air, respiratory rate 22 per minute, heart rate 110 beats per minute, blood pressure is 103/71 mmHg, and temperature 99.3 F. Abdominal examination reveals diffuse tenderness without guarding. Laboratory testing reveals a blood glucose level of 420 mg/dL (65- 110). An arterial blood gas analysis shows anion-gap metabolic acidosis. Which of the following is responsible for the decreased pH seen in this patient?
Increased synthesis of acetoacetate
PBL #039 Ms. Vera
Discuss the difference between tumor suppressors and oncogenes, both in terms of their action and their perturbation in cancer
Tumor suppressors normally inhibit cellular proliferation (they are the brakes) and when mutated are loss of function, while oncogenes are promoters of proliferation (they are the gas pedals) and when mutated are gain of function.
Lecture #060