Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0016719 (Friedreich's ataxia)
 2,098 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two unrelated patients with Friedreich ataxia were deficient in the activity of the enzyme lipoamide dehydrogenase (LAD). The enzymes from the patients' platelets differed significantly from controls in activity, in KM for lipoamide, and in KM for NADH. The data are consistent with a structural mutation of the gene coding for LAD.
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PMID:Kinetic evidence for a structural abnormality of lipoamide dehydrogenase in two patients with Friedreich ataxia. 56 87

Muscle pyruvate dehydrogenase complex (PDHC) activity was studied in 70 patients with different neuromuscular disorders. Children had higher total PDHC and lipoamide dehydrogenase (LAD) activities than adults. There were no significant differences in muscle PDHC activity in patients with Friedreich ataxia, patients with other ataxias, or age-matched controls. Kinetic analysis of LAD showed no differences in Km for lipoamide between Friedreich ataxia patients and controls.
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PMID:Human muscle pyruvate dehydrogenase activity. 668 64

To see whether kinetic assays of lipoamide dehydrogenase could be used for carrier detection or preclinical diagnosis, Michaelis-Menten constants (KmL and KmH) for the enzyme were determined in platelets from families with a form of recessive Friedreich ataxia and low activities of the enzyme. The KmL of patients' enzyme was 132 +/- 5 microM lipoamide (mean +/- SEM) versus 56 +/- 9 microM for controls (p less than 0.001), and KmH for the patients was 421 +/- 19 microM versus 147 +/- 14 microM for the controls (p less than 0.001). The activity and Km values of one patient's enzyme were abnormal 1 year before neurologic signs appeared. The Km values for the enzymes of the six parents were also elevated (average KmL, 105 +/- 10 microM; average KmH, 378 +/- 47 microM, p less than 0.02). The maximal activities of the parents' enzymes, relative to a mitochondrial marker, were intermediate between the mean maximal control activity and the mean activity for the affected offspring. The data suggest that the abnormalities of lipoamide dehydrogenase are inherited in a recessive pattern in these families.
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PMID:Preclinical diagnosis and carrier detection in ataxia associated with abnormalities of lipoamide dehydrogenase. 689 25

Serum lipoamide dehydrogenase activity and kinetics were studied in nine patients with Friedreich's ataxia before and three months after therapy with oral lecithin. Results disclosed a significant reduction in LAD inhibition by NADH in all patients after therapy. Three patients normalized their increased Km for lipoamide and one patient showed the opposite results after therapy. Two patients ceased lecithin after one month. All seven patients who remained in the trial group and one additional patient, showed subjective and objective signs of improvement in physical resistance. This study has offered some biochemical basis for the apparent clinical improvement in patients with Friedreich's ataxia who undergo lecithin therapy.
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PMID:Correlation between serum lipoamide dehydrogenase activity and phosphatidylcholine therapy in Friedreich's ataxia. 689 63

Lecithin and safflower oil brought about the same changes in serum LAD activity and kinetics in patients with Friedreich's Ataxia as in controls when results of this double-blind crossover study were analyzed according to group assignation. According to functional stages, pretrial LAD activity decreased with advancing severity while Km for lipoamide increased. Lecithin and safflower oil supplements corrected the elevated Km for lipoamide but produced a further reduction in LAD activity. These changes may have been due to the increased intake of linoleic acid, a precursor of lipoic acid, which is present in high percentage in both lecithin and safflower oil. Results of the biochemical study thus agreed with the clinical data gathered during the course of the one-year trial in suggesting that linoleic acid may well have been the active factor through which biochemical and clinical improvement was previously observed in patients with Friedreich's Ataxia supplemented with lecithin.
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PMID:Oral lecithin and linoleic acid in Friedreich's ataxia: III. Biochemical results. 689 72

Mitochondrial Targeting Sequences (MTSs) are responsible for trafficking nuclear-encoded proteins into mitochondria. Once entering the mitochondria, the MTS is recognized and cleaved off. Some MTSs are long and undergo two-step processing, as in the case of the human frataxin (FXN) protein (80aa), implicated in Friedreich's ataxia (FA). Therefore, we chose the FXN protein to examine whether nuclear-encoded mitochondrial proteins can efficiently be targeted via a heterologous MTS (hMTS) and deliver a functional protein into mitochondria. We examined three hMTSs; that of citrate synthase (cs), lipoamide deydrogenase (LAD) and C6ORF66 (ORF), as classically MTS sequences, known to be removed by one-step processing, to deliver FXN into mitochondria, in the form of fusion proteins. We demonstrate that using hMTSs for delivering FXN results in the production of 4-5-fold larger amounts of the fusion proteins, and at 4-5-fold higher concentrations. Moreover, hMTSs delivered a functional FXN protein into the mitochondria even more efficiently than the native MTSfxn, as evidenced by the rescue of FA patients' cells from oxidative stress; demonstrating a 18%-54% increase in cell survival; and a 13%-33% increase in ATP levels, as compared to the fusion protein carrying the native MTS. One fusion protein with MTScs increased aconitase activity within patients' cells, by 400-fold. The implications form our studies are of vast importance for both basic and translational research of mitochondrial proteins as any mitochondrial protein can be delivered efficiently by an hMTS. Moreover, effective targeting of functional proteins is important for restoration of mitochondrial function and treatment of related disorders.
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PMID:Heterologous mitochondrial targeting sequences can deliver functional proteins into mitochondria. 2777 40