Megaloblastic Anemia and Other Causes of Macrocytosis

Department of Internal Medicine, Marshfield Clinic, 1000 North Oak Avenue, Marshfield, WI 54449, USA.
Clinical Medicine &amp Research 10/2006; 4(3):236-41. DOI: 10.3121/cmr.4.3.236
Source: PubMed
23 Reads
    • "THF is a co-factor critical in the metabolism of amino acids and nucleic acids. The deficiency in THF (possibly caused by the deficiency in FOL) leads to megalobalstic anemia [42]. Therefore, the delivery of human DHFR variants efficiently catalyzing the conversion reaction of FOL or the human DHFR genes into megaloblastic anemia patients is a potential therapeutic strategy. "
    [Show abstract] [Hide abstract]
    ABSTRACT: As the number of reactions requiring biotransformation continues to grow, manipulating the enzyme substrate specificity becomes very important. Complementary to conventional enzyme engineering techniques based on only natural amino acids, we hypothesized that the site-specific incorporation of a non-natural amino acid in vivo into an enzyme can be used to re-design the active site for the altered substrate specificity. To test our hypothesis, we introduced the non-natural amino acid L-2-naphthylalanine (2Nal) into the active site of the model enzyme murine dihydrofolate reductase (mDHFR). We explored whether the substrate specificity of the enzyme could be switched from the good substrate dihydrofolate (DHF) to the poor substrate folate (FOL). We used two protein design programs (RosettaLigand and RosettaDesign) to calculate ligand docking and conformational stability, respectively, for the evaluation of multiples sites in the mDHFR. From the calculations, position 31 was predicted as an optimal 2Nal incorporation site. One mDHFR variant containing 2Nal at position 31 (mDHFR2Nal31) was expressed in the Escherichia coli expression host cells equipped with the engineered yeast phenylalanyl-tRNA and phenylalanyl-tRNA synthetase pair. As expected, the kinetic assays of purified mDHFR variant revealed that mDHFR2Nal31 has the enhanced binding affinity toward FOL and also exhibits 7.6-fold enhanced catalytic efficiency of FOL over DHF compared to mDHFRWT.
    Biochemical Engineering Journal 07/2015; 99. DOI:10.1016/j.bej.2015.03.011 · 2.47 Impact Factor
  • Source
    • "Vitamin B12 deficiency is classically associated with overt haematological findings like macrocytic red blood cells (mean cell volume [MCV]> 100 fl) with/without anaemia, ovalocytes, hyper segmented white blood cells (i.e. >5% of neutrophils with ≥5 lobes) and pancytopenia [9]. Due to defective cell repair processes, atrophic glossitis, stomatitis and malabsorption due to villi atrophy and mucositis are also common. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Vitamin B12 is an essential micronutrient required for optimal hemopoetic, neuro-cognitive and cardiovascular function. Biochemical and clinical vitamin B12 deficiency has been demonstrated to be highly prevalent among patients with type 1 and type 2 diabetes mellitus. It presents with diverse clinical manifestations ranging from impaired memory, dementia, delirium, peripheral neuropathy, sub acute combined degeneration of the spinal cord, megaloblastic anemia and pancytopenia. This review article offers a current perspective on the physiological roles of vitamin B12, proposed pathophysiological mechanisms of vitamin B12 deficiency, screening for vitamin B12 deficiency and vitamin B12 supplementation among patients with diabetes mellitus.
    Journal of Diabetes and Metabolic Disorders 05/2013; 12(1):17. DOI:10.1186/2251-6581-12-17
  • Source
    • "Number of red blood cells was slightly decreased (Fig. 2A), the mean corpuscular volume (Fig. 2B) and mean corpuscular hemoglobin (Fig. 2C) were significantly increased. This observation might indicate impaired cell division during erythropoiesis [34]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Nuclear myosin I (NM1) is a nuclear isoform of the well-known "cytoplasmic" Myosin 1c protein (Myo1c). Located on the 11(th) chromosome in mice, NM1 results from an alternative start of transcription of the Myo1c gene adding an extra 16 amino acids at the N-terminus. Previous studies revealed its roles in RNA Polymerase I and RNA Polymerase II transcription, chromatin remodeling, and chromosomal movements. Its nuclear localization signal is localized in the middle of the molecule and therefore directs both Myosin 1c isoforms to the nucleus. In order to trace specific functions of the NM1 isoform, we generated mice lacking the NM1 start codon without affecting the cytoplasmic Myo1c protein. Mutant mice were analyzed in a comprehensive phenotypic screen in cooperation with the German Mouse Clinic. Strikingly, no obvious phenotype related to previously described functions has been observed. However, we found minor changes in bone mineral density and the number and size of red blood cells in knock-out mice, which are most probably not related to previously described functions of NM1 in the nucleus. In Myo1c/NM1 depleted U2OS cells, the level of Pol I transcription was restored by overexpression of shRNA-resistant mouse Myo1c. Moreover, we found Myo1c interacting with Pol II. The ratio between Myo1c and NM1 proteins were similar in the nucleus and deletion of NM1 did not cause any compensatory overexpression of Myo1c protein. We observed that Myo1c can replace NM1 in its nuclear functions. Amount of both proteins is nearly equal and NM1 knock-out does not cause any compensatory overexpression of Myo1c. We therefore suggest that both isoforms can substitute each other in nuclear processes.
    PLoS ONE 04/2013; 8(4):e61406. DOI:10.1371/journal.pone.0061406 · 3.23 Impact Factor
Show more


23 Reads
Available from