Category: Metabolism of nucleotides

trial 4 0

Hydroxyurea in the treatment of Leukemia

Case details A physician evaluates a 32-year-old patient for fatigue. The patient is found to have an elevated white blood cell count and an enlarged spleen. A referral to an oncologist results in a diagnosis of chronic myelogenous leukemia. Treatment with hydroxyurea, a ribonucleotide reductase inhibitor is begun. The normal functioning of this enzyme is to do which of the following? A. Converts xanthine to uric acid B. Converts ribonucleotides to deoxyribonucleotides C. Degrades guanine to xanthine D. Degrades AMP to IMP E. Converts PRPP to phosphoribosylamine   The correct answer is- B- Converts ribonucleotides to deoxyribonucleotides. Either hydroxyurea or...

trial 4 0

Reaction catalyzed by Xanthine oxidase

Allopurinol, (the inhibitor of xanthine oxidase), is used in the treatment of Gout. More recently, febuxostat, a novel nonpurine analog inhibitor of xanthine oxidase, has been used. Which of the following reactions is catalyzed by xanthine oxidase? A. Hypoxanthine to Xanthine B. Xanthine to Hypoxanthine C. Hypoxanthine to uric acid D. Inosine to hypoxanthine E. Adenosine to Inosine. The correct answer is- A, Conversion of hypoxanthine to xanthine. Basic concept Gout is a metabolic disease most often affecting middle-aged to elderly men and postmenopausal women. It is the result of an increased body pool of urate with hyperuricemia, typically characterized...

trial 4 0

Role of “Nucleoside analogs” in HIV infection

Case details A 34-year-old homosexual man has recently been diagnosed with HIV (human immunodeficiency virus) infection. His CD4+ T-cell count has dramatically decreased, and he has a high viral load. He has been referred to an infectious disease clinic where he has been prescribed with a nucleoside analog. The nucleoside analogs inhibit DNA synthesis. Which of the following chemical groups essentially required for DNA polymerization is absent in the nucleoside analogs? A. 5′ Phosphate B. 3′ Hydroxyl C. 2′ Methyl D. 3′-Phosphate E. 5′ Hydroxyl. The correct answer is- B-3′ Hydroxyl. Basic concept Nucleosides Nucleosides are derivatives of purines and pyrimidines...

trial 4 0

Condition causing hypouricemia ?

Which out of the following conditions is associated with hypouricemia? A. Lesch Nyhan syndrome B. Adenosine deaminase deficiency C. Over activity of PRPP synthetase D. Over activity of Amido transferase E. Von Gierke’s disease Answer- The correct answer is Adenosine deaminase deficiency. Adenosine deaminase deficiency, also called ADA deficiency or ADA-SCID is an Autosomal recessive disorder that causes immunodeficiency. It accounts for about 15% of all cases of severe combined immunodeficiency (SCID). The SCID syndrome is characterized by gross functional impairment of both humoral and cell-mediated immunity and by susceptibility to devastating fungal, bacterial, and viral infections. Adenosine deaminase- catalyzes...

trial 4 0

Case discussion- Treatment with Hydroxyurea- A case of chronic myelogenous Leukemia

Case Details A physician evaluates a 32-year-old patient for fatigue. The patient is found to have an elevated white blood cell count and an enlarged spleen. A referral to an oncologist results in a diagnosis of chronic myelogenous leukemia. Treatment with hydroxyurea, a ribonucleotide reductase inhibitor is begun. The normal functioning of this enzyme is to do which of the followings? A. Converts xanthine to uric acid B. Converts ribonucleotides to deoxy ribonucleotides C. Degrades guanine to xanthine D. Degrades AMP to IMP E. Converts PRPP to phosphoribosylamine Answer- The correct answer is- B Hydroxyurea is prescribed to the patients...

trial 4 0

Treatment with hyrdroxyurea- A case of chronic myelogenous leukemia

A physician evaluates a 32-year-old patient for fatigue. The patient is found to have an elevated white blood cell count and an enlarged spleen. A referral to an oncologist results in a diagnosis of chronic myelogenous leukemia. Treatment with hydroxyurea, a ribonucleotide reductase inhibitor is begun. The normal functioning of this enzyme is to do which of the followings ? a) Converts xanthine to uric acid b) Converts ribonucleotides to deoxy ribonucleotides c) Degrades guanine to xanthine d) Degrades AMP to IMP e) Converts PRPP to phosphoribosylamine   Figure- Blood film of a patient suffering from Chronic myelogenous leukemia For...

trial 4 0

Megaloblastic anemia in the presence of normal Folic acid and Vitamin B12- Case discussion

Case details A 6-month-old infant is seen by the pediatrician for developmental delay. Blood work shows megaloblastic anemia, although measurements of B12 and folate are in the high normal range. Urinalysis demonstrates, upon standing, the formation of a crystalline substance. Supplementation of the child’s diet with uridine reversed virtually all of the clinical problems. The crystalline substance was most likely composed of which of the following? A. Uracil B. Thymine C. Orotate D. Aspartate E. Cytosine Answer- The correct answer is C-Orotate. The child seems to be suffering from Hereditary orotic aciduria. Orotic aciduria refers to an excessive excretion of orotic acid...

trial 4 0

Megaloblastic anemia in the presence of normal Folic acid and B12- A case report

Case details A 6-month-old infant is seen by the pediatrician for developmental delay. Blood work shows megaloblastic anemia, although measurements of B12 and folate are in the high normal range. Urinalysis demonstrates, upon standing, the formation of a crystalline substance. Supplementation of the child’s diet with uridine reversed virtually all of the clinical problems. The crystalline substance was most likely composed of which of the following? A. Uracil B. Thymine C. Orotate D. Aspartate E. Cytosine   Figure- Megaloblastic anemia and macrocytosis To check the answer follow the link http://usmle.biochemistryformedics.com/megaloblastic-anemia-in-the-presence-of-normal-folic-acid-and-vitamin-b12-case-discussion/ Please help Biochemistry for Medics by “CLICKING ON THE ADVERTISEMENTS” every time...

trial 4 0

Methotrexate therapy- Case discussion

Case details A 60-year-old female patient has psoriasis and has been treated with methotrexate for several years. She has no other medical problems and her preventive screenings, including fecal occult blood tests and colonoscopy, have all been normal. She has developed an anemia. Which of the following would you expect to find when working up her anemia? A. A macrocytic anemia B. A microcytic anemia C. Thalassemia D. Spherocytosis E. A low vitamin B12 level Answer- The correct answer is- A, Macrocytic anemia. Methotrexate is an antimetabolite, it is recommended as a treatment for psoriasis to inhibit cellular proliferation. It...

trial 4 2

Methotrexate therapy- A case report

A 60-year-old female patient has psoriasis and has been treated with methotrexate for several years. She has no other medical problems and her preventive screenings, including fecal occult blood tests and colonoscopy, have all been normal. She has developed an anemia. Which of the following would you expect to find  when working up her anemia? A. A macrocytic anemia B. A microcytic anemia C. Thalassemia D. Spherocytosis E. A low vitamin B12 level For answer follow the link http://usmle.biochemistryformedics.com/methotrexate-therapy-case-discussion/ Please help Biochemistry for Medics by “CLICKING ON THE ADVERTISEMENTS” every time you visit us. Thank you!

Copy Protected by Chetan's WP-Copyprotect.