Recent questions without an upvoted answer

by admin (2.6k points) in Biochemistry asked Sep 15

A scientist working in a research laboratory has been examining different agonists of serotonin receptor 1B (5-HT1B), a G-protein-coupled re- ceptor. Compound A has a much higher affin- ity for 5-HT1B than compound B. Both com- pounds have a higher affinity for the receptor than serotonin. Which of the following de- scribes the relationship between compound A and compound B when considering the guan- ine-nucleotide exchange activity of 5-HT1B?

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by admin (2.6k points) in Biochemistry asked Sep 15

As increased intracellular calcium is detrimen- tal to the cell, calcium homeostasis is tightly regulated both across the cell membrane and within the cell via sequestration in the en- doplasmic reticulum and mitochondria. In which of the following ways does increased intracellular calcium concentration cause the most cell damage?

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by admin (2.6k points) in Biochemistry asked Sep 15

A 45-year-old white woman presents to her physician complaining of several months of worsening shortness of breath. Previously she was told she had asthma because she was hav- ing intermittent episodes of wheezing com- bined with a productive cough and difficulty catching her breath. She used to run two miles every morning but can no longer walk more than 10 city blocks without stopping. She has never smoked. On physical examination she is using her accessory muscles to assist with res- piration. Pulmonary examination is notable for an increased decreased FEV1/FVC ratio, decreased air movement with each breath, and increased resonance upon percussion. X-ray of the chest is shown in the image. Which of the following is the most likely underlying cause for this patient’s disease?

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by admin (2.6k points) in Biochemistry asked Sep 15

A nucleic acid fragment is added to four dif- ferent tubes along with a polymerase, a radio- labeled primer, and deoxynucleotides. Each tube also contains one of the four bases as dideoxynucleotides. The four tubes are then run on electrophoresis gel and visualized by autoradiography. For which of the following purposes would the described laboratory tech- nique be utilized?

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by admin (2.6k points) in Biochemistry asked Sep 15

A 57-year-old woman visits her primary care physician. Laboratory studies reveal an LDL of 194 mg/dL and HDL of 41 mg/dL. Her phy- sician begins therapy with a drug that inhibits production of mevalonic acid. Which of the following is a common side effect of this ther- apy?

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by admin (2.6k points) in Biochemistry asked Sep 13

A patient who is a carrier of sickle cell trait presents to the clinic. The single base-pair mu- tation for sickle cell anemia destroys the MstII restriction enzyme recognition site represented by an asterisk in the image. The restriction enzyme-binding sites are shown as arrows on the map. DNA from this patient is treated with MstII and run on an electrophoresis gel. The DNA is then hybridized with a labeled probe that binds to the normal gene in the posi- tion shown on the map. In the Southern blot shown in the image, which lane represents the patient?

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by admin (2.6k points) in Biochemistry asked Sep 13

A metabolic process is pictured below. Which intermediate in this process inhibits the rate- limiting enzyme of glycolysis and activates the rate-limiting enzyme of fatty acid synthesis?

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by admin (2.6k points) in Biochemistry asked Sep 10

A 6-year-old boy presents to his pediatrician with skin lesions all over his body. For several years he has been very sensitive to sunlight. Neither the boy’s parents nor his siblings have the same skin lesions or sun sensitivity. Biop- sies of several of the boy’s lesions reveal squa- mous cell carcinoma. Which mutation would one expect to see in this patient’s DNA?

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by admin (2.6k points) in general principle asked Sep 9

A 45-year-old man presents to a psychiatrist at his wife’s prompting. He is an English profes- sor at the University of Virginia and regularly wins accolades for his well-organized and ar- ticulate lectures. In the past three months, he has become convinced that his wife is having an affair with a co-worker, despite her protests to the contrary. His wife recently discovered that he hired a private investigator to track her whereabouts. He is very defensive when the counselor questions his suspicions about his wife. Mental status examination reveals a well- dressed, middle-aged man without hallucina- tions or other mood disturbances. His speech is normal and displays an appropriate affec- tive range. Which of the following is the most likely diagnosis?

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by admin (2.6k points) in general principle asked Sep 9

A retrospective cohort study is examining birth complications in women with diabetes. The study determines that babies are more likely to be born large for gestational age (LGA) if the mother has diabetes. The relative risk for the study is calculated to be 4. Which of the fol- lowing accurately describes this relative risk?

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by admin (2.6k points) in general principle asked Sep 9

A 3-year-old girl presents for her regular check- up. Her mother reports that she is fully toilet trained, and that she can dress and undress with minor assistance. She speaks in full sen- tences, can name four colors, and can copy a simple circle drawing. What other milestone would this child most likely have reached since her last visit one year ago?

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by admin (2.6k points) in general principle asked Sep 9

A 54-year-old man with a history of poorly con- trolled hypertension complains of new-onset headaches. His mother passed away at an early age due to a stroke, and his father died of a myocardial infarction. When asked why he does not take better care of his blood pressure, he states that he is so busy with work and with the church that, by the end of the day, he often forgets to take his pills. He states that he “feels fine, anyway.” What ego defense mechanism is this patient using?

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by admin (2.6k points) in general principle asked Sep 9

A 70-year-old man comes into his doctor’s of- fice for a routine check-up. His past medi- cal history is significant for a heart attack, for which he takes a daily baby aspirin and a b-blocker. He practices safe habits and always wears his seat belt while driving. His health has been “great” for the past few years, al- though he is concerned about his wife because she recently suffered a mild stroke. He denies any visual loss or motor or sensory weakness. The patient’s physical examination is unre- markable. Which of the following is the lead- ing cause of death among people age 65 years or older?

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by admin (2.6k points) in general principle asked Sep 9

A 10-year-old Hispanic boy is admitted for bone marrow transplantation as treatment for acute myelogenous leukemia. The doctor wants to enroll the patient in a clinical trial for a new pain medication, but both the par- ents speak only Spanish. The consent form is in English, and the physician has a limited knowledge of Spanish. What is the physician’s best option for obtaining consent from this pa- tient?

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by admin (2.6k points) in general principle asked Sep 9

An 11-year-old girl is brought to the pediatri- cian with complaints of back pain. On physical examination, a right thoracic scoliotic curve is noted. The pediatrician mentions to the parent that the development of adolescent idiopathic scoliosis is due to the girl being at peak height growth velocity. Peak height velocity is associ- ated with a certain Tanner stage; what other physical attributes would one expect to occur in this girl at the same time?

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by admin (2.6k points) asked Sep 9

A group of scientists decides to conduct a study addressing the long-term effects of maternal alcohol consumption on their infants after conception. Two hundred women, including those who suffer from alcoholism and those who do not, are recruited into the study when they present for their first primary care visit. A medical history is taken on alcohol use, prena- tal care, nutritional status, and smoking behav- iors; these are measured monthly during the pregnancy. The researchers follow the wom- en’s pregnancies until term, after which they devote their attention to the health and behav- iors of the offspring. Which of the following is the most appropriate statistic the research- ers will be able to calculate as a result of their study?

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by admin (2.6k points) asked Sep 9

A 17-year-old girl presents to her primary care physician with a complaint of missed menses. A urine pregnancy test confirms that she is pregnant. She returns to the office two weeks later asking for recommendations on obtaining an abortion. She explains that she works, lives with her husband, and is not ready for a child. She decides that she does not want to notify anyone, and says she has chosen not to talk with her parents for many months. Her doctor understands that he must abide by her wishes because she is emancipated. Which of the fol- lowing makes this patient emancipated?

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by admin (2.6k points) asked Sep 9

A 66-year-old man presents to his primary care physician with a complaint of erectile dysfunc- tion. His past history is significant for hyper- tension, type 2 diabetes mellitus, peripheral vascular disease, and coronary artery disease status postmyocardial infarction. His current medications are propranolol, captopril, aspirin, lovastatin, metformin, fluoxetine, and sublin- gual nitroglycerin. On further questioning, he admits to wanting a prescription for sildenafil. Which of his medications is unsafe to take with sildenafil?

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by admin (2.6k points) asked Sep 9

A new screening test for the development of mitral regurgitation in the setting of rheumatic fever is created. A study of 1000 patients with a history of Streptococcus pyogenes infection and a diagnosis of rheumatic fever is performed using this test, which has 90% sensitivity and 85% specificity. The prevalence of mitral re- gurgitation in this population is estimated to be 40%. What is the positive predictive value of this test?

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by admin (2.6k points) asked Sep 9

A 2-month-old boy is brought to the emer- gency department with respiratory insuffi- ciency and failure to thrive. The pregnancy and perinatal course were uneventful. Gener- alized hypotonia, tongue fasciculations, and flaccid paralysis are noted on physical exami- nation. His hospital stay is complicated by the development of tracheobronchomalacia and respiratory insufficiency that necessitates me- chanical ventilation. Despite these efforts, the patient dies of respiratory complications. Muscle biopsy shows denervation and panfas- cicular atrophy. A genetics consult yields the pedigree shown in the image. Which of the following diseases is most consistent with this patient’s presentation and the pedigree shown in the image?

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