Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acute intermittent porphyria (AIP) is a neuropathic disease caused by a dominant inherited deficiency in porphobilinogen deaminase (PBGD). We investigated the expression and the degradation of the human PBGD-mutations G748A, G748C and 887insA following transfection into human SH-SY5Y neuroblastoma cells. Mutant proteins exhibited reduced protein expression compared to transfected wild-type (wt) PBGD as revealed by Western blotting. The transcription levels assessed by real-time PCR of these mutant species were identical to those of the wild type. Immuno-fluorescence microscopy revealed reduced cellular distribution of the mutated PBGDs in the cytosol and the nucleus in comparison to the wild-type PBGD. Enhanced cellular accumulation of the mutated and wild-type PBGDs was detected following inhibition of the proteasome by the inhibitors CLBL and hemin. Elevated expression of wt and mutated PBGD protein levels was either achieved by hemin or heme-arginate treatment. On the other hand, enhanced PBGD degradation was achieved by lead poisoning of ALAD in the SH-SY5Y cells concomitant with acceleration of proteasomal activity, most probably by ALAD participation in proteasomal regulation [G.G. Guo, M. Gu, J.D. Etlinger, 240-kDa proteasome inhibitor (CF-2) is identical to delta-aminolevulinic acid dehydratase. J Biol Chem 1994; 269:12399-402.] Our results suggest that the difference in expression between the wild-type and mutant proteins appears to be regulated on the level of protein degradation. In conclusion, we demonstrate that the PBGD cellular pool is controlled by the proteasome activity, which in turn is down regulated by hemin or up-regulated by Pb-ALAD.
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PMID:Proteasomal degradation regulates expression of porphobilinogen deaminase (PBGD) mutants of acute intermittent porphyria. 1693 74

Newborn screening programs use whole blood dried on filter paper as the standard specimen. Metabolites are reasonably stable and can easily be sent to screening laboratories by regular mail. The recommended sample collection procedure is to spot native blood without anticoagulants onto the filter paper, because anticoagulants can interfere with the different laboratory methods. However, visual examination of the blood spots cannot always detect contamination. In this study, whole blood was drawn by venous puncture from a healthy volunteer, spiked with the corresponding metabolites and EDTA, and spotted onto filter paper. TSH and 17alpha-hydroxyprogesterone were determined by time resolved fluoroimmunoassays with the AutoDelfia system. Total galactose, biotinidase activity, and galactose-1-phosphate uridyltransferase activity were measured photometrically or fluorometrically. Succinyl acetone was estimated indirectly through the inhibition of porphobilinogen synthase activity (PBGS assay). EDTA, amino acids, and acylcarnitines were converted to the corresponding butyl esters, after extraction with methanol, and analysed by LC-MS/MS. EDTA contamination gives falsely elevated 17-OHP values and falsely reduced TSH and PBGS values. The inclusion of an EDTA determination in routine screening revealed that at least 0.06% of newborn screening samples were contaminated with EDTA. In conclusion, non-conformity during the pre-analytical phase is a source of false positive and false negative screening results. Determination of EDTA from NBS blood spots can reliably identify these samples and prevent screening errors.
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PMID:Determination of EDTA in dried blood samples by tandem mass spectrometry avoids serious errors in newborn screening. 1865 Nov 77