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Wilson C, Knoll D, de Hora M, Kyle C, Glamuzina E, Webster D. The decision to discontinue screening for carnitine uptake disorder in New Zealand. J Inherit Metab Dis 2019; 42:86-92. [PMID: 30740730 DOI: 10.1002/jimd.12030] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
When screening for carnitine uptake disorder (CUD), the New Zealand (NZ) newborn screening (NBS) service identified infants as screen-positive if they had initial and repeat free carnitine (C0) levels of less than 5.0 μmol/L. Since 2006, the NBS service has identified two infants with biochemical and genetic features consistent with neonatal CUD and nine mothers with features consistent with maternal CUD. A review of the literature suggests that these nine women reflect less than half the true prevalence and that CUD is relatively common. However, the NZ results (two infants) suggest a very low sensitivity and positive predictive value of NBS. While patients presenting with significant disease due to CUD are well described, the majority of adults with CUD are asymptomatic. Nonetheless, treatment with high-dose oral L-carnitine is recommended. Compliance with oral L-carnitine is likely to be poor long term. This may represent a specific risk as treatment could repress the usual compensatory mechanisms seen in CUD, such that a sudden discontinuation of treatment may be dangerous. L-carnitine is metabolized to trimethylamine-N-oxide (TMAO) and treated patients have extremely high plasma TMAO levels. TMAO is an independent risk factor for atherosclerosis and, thus, caution should be exercised regarding long-term treatment with high-dose carnitine of asymptomatic patients who may have a biochemical profile without disease. Due to these concerns, the NZ Newborn Metabolic Screening Programme (NMSP) initiated a review via a series of advisory and governance committees and decided to discontinue screening for CUD.
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Affiliation(s)
- Callum Wilson
- National Metabolic Service, Starship Children's Hospital, P.O. Box 92024, Auckland 1142, New Zealand
| | - Detlef Knoll
- Newborn Metabolic Screening Unit, Auckland City Hospital, Auckland, New Zealand
| | - Mark de Hora
- Newborn Metabolic Screening Programme, LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Campbell Kyle
- LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Emma Glamuzina
- National Metabolic Service, Starship Children's Hospital, P.O. Box 92024, Auckland 1142, New Zealand
| | - Dianne Webster
- Newborn Metabolic Screening Programme, LabPlus, Auckland City Hospital, Auckland, New Zealand
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Abstract
Mitochondria are highly dynamic organelles and undergo continuous fission and fusion events in physiological situations. It was observed that mitochondrial morphology and number are changed in living cells during cellular differentiation, development, and under pathological conditions including muscle dystrophy, cardiomyopathy, and cancer. Defined sets of proteins are known to mediate mitochondrial fission and fusion and to constitute regulatory components controlling mitochondrial dynamics. In the present study, we first investigated mitochondrial dynamics during the cell cycle progression, and found that mitochondria exist as filamentous network structures throughout the cell cycle progression, changing their morphology, distribution, and abundance. In addition, we found that a mouse homolog of human DNA polymerase delta interacting protein 38, referred to as Mitogenin I, and mitochondrial single-stranded DNA-binding protein (mtSSB), identified as upregulated genes in the heart of mice with juvenile visceral steatosis, play a role in the regulation of mitochondrial morphology.
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Affiliation(s)
- Midori Suenaga
- Department of Medical Pharmacology, Faculty of Pharmaceutical Science, Tokushima Bunri University, Tokushima, Japan.
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Mouse cardiac acyl coenzyme a synthetase 1 deficiency impairs Fatty Acid oxidation and induces cardiac hypertrophy. Mol Cell Biol 2011; 31:1252-62. [PMID: 21245374 DOI: 10.1128/mcb.01085-10] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Long-chain acyl coenzyme A (acyl-CoA) synthetase isoform 1 (ACSL1) catalyzes the synthesis of acyl-CoA from long-chain fatty acids and contributes the majority of cardiac long-chain acyl-CoA synthetase activity. To understand its functional role in the heart, we studied mice lacking ACSL1 globally (Acsl1(T-/-)) and mice lacking ACSL1 in heart ventricles (Acsl1(H-/-)) at different times. Compared to littermate controls, heart ventricular ACSL activity in Acsl1(T-/-) mice was reduced more than 90%, acyl-CoA content was 65% lower, and long-chain acyl-carnitine content was 80 to 90% lower. The rate of [(14)C]palmitate oxidation in both heart homogenate and mitochondria was 90% lower than in the controls, and the maximal rates of [(14)C]pyruvate and [(14)C]glucose oxidation were each 20% higher. The mitochondrial area was 54% greater than in the controls with twice as much mitochondrial DNA, and the mRNA abundance of Pgc1α and Errα increased by 100% and 41%, respectively. Compared to the controls, Acsl1(T-/-) and Acsl1(H-/-) hearts were hypertrophied, and the phosphorylation of S6 kinase, a target of mammalian target of rapamycin (mTOR) kinase, increased 5-fold. Our data suggest that ACSL1 is required to synthesize the acyl-CoAs that are oxidized by the heart, and that without ACSL1, diminished fatty acid (FA) oxidation and compensatory catabolism of glucose and amino acids lead to mTOR activation and cardiac hypertrophy without lipid accumulation or immediate cardiac dysfunction.
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Furusawa H, Sato Y, Tanaka Y, Inai Y, Amano A, Iwama M, Kondo Y, Handa S, Murata A, Nishikimi M, Goto S, Maruyama N, Takahashi R, Ishigami A. Vitamin C Is Not Essential for Carnitine Biosynthesis in Vivo: Verification in Vitamin C-Depleted Senescence Marker Protein-30/Gluconolactonase Knockout Mice. Biol Pharm Bull 2008; 31:1673-9. [DOI: 10.1248/bpb.31.1673] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hajime Furusawa
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Toho University
- Aging Regulation, Tokyo Metropolitan Institute of Gerontology
| | - Yasunori Sato
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Toho University
- Aging Regulation, Tokyo Metropolitan Institute of Gerontology
| | - Yasukazu Tanaka
- Neuroscience and Brain Function, Tokyo Metropolitan Institute of Gerontology
| | - Yoko Inai
- Department of Biochemistry, Wakayama Medical University
| | - Akiko Amano
- Aging Regulation, Tokyo Metropolitan Institute of Gerontology
| | - Mizuki Iwama
- Aging Regulation, Tokyo Metropolitan Institute of Gerontology
| | - Yoshitaka Kondo
- Aging Regulation, Tokyo Metropolitan Institute of Gerontology
| | - Setsuko Handa
- Aging Regulation, Tokyo Metropolitan Institute of Gerontology
| | - Akira Murata
- Department of Food and Nutrition, Saga Junior College
| | | | - Sataro Goto
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Toho University
- Aging Regulation, Tokyo Metropolitan Institute of Gerontology
| | - Naoki Maruyama
- Aging Regulation, Tokyo Metropolitan Institute of Gerontology
| | - Ryoya Takahashi
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Toho University
| | - Akihito Ishigami
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Toho University
- Aging Regulation, Tokyo Metropolitan Institute of Gerontology
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Kuwajima M, Fujihara H, Sei H, Umehara A, Sei M, Tsuda TT, Sukeno A, Okamoto T, Inubushi A, Ueta Y, Doi T, Kido H. Reduced carnitine level causes death from hypoglycemia: possible involvement of suppression of hypothalamic orexin expression during weaning period. Endocr J 2007; 54:911-25. [PMID: 18025760 DOI: 10.1507/endocrj.k07-044] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The mechanism of onset of hypoglycemia in patients with carnitine deficiency has yet to be determined. Using mice with systemic carnitine deficiency (JVS mice), we examined this mechanism, focusing on the weaning period (days 14-28 postpartum). For normal mice, the survival rate was 100%, and no hypoglycemia was observed at all. Gastric lactose began to decrease on day 17, and cellulose increased sharply in amount thereafter. For JVS mice, the survival rate was 77% on day 14 and 28% on day 28. From day 21 on, hypoglycemia was noted. Gastric lactose had disappeared almost completely by day 17, and cellulose was almost undetectable from days 14 to 28. Expression of orexin mRNA in the hypothalamus did not differ between JVS and normal mice on day 14, but was suppressed in JVS mice on days 21 and 28. When JVS mice were fed a carnitine-rich diet, suppression of expression of orexin mRNA in hypothalamus was eliminated, and on day 28 lactose and cellulose were detected in the stomach without hypoglycemia. In conclusion, the suppression of the expression of orexin in the hypothalamus during the weaning period may be involved in the marked anorexia in JVS mice, which eventually leads to death from hypoglycemia.
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Affiliation(s)
- Masamichi Kuwajima
- Department of Clinical Biology and Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
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Arakaki N, Nishihama T, Kohda A, Owaki H, Kuramoto Y, Abe R, Kita T, Suenaga M, Himeda T, Kuwajima M, Shibata H, Higuti T. Regulation of mitochondrial morphology and cell survival by Mitogenin I and mitochondrial single-stranded DNA binding protein. Biochim Biophys Acta Gen Subj 2006; 1760:1364-72. [PMID: 16860483 DOI: 10.1016/j.bbagen.2006.05.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 05/26/2006] [Accepted: 05/31/2006] [Indexed: 10/24/2022]
Abstract
We found that a mouse homolog of human DNA polymerase delta interacting protein 38, referred to as Mitogenin I in this paper, and mitochondrial single-stranded DNA-binding protein (mtSSB), identified as upregulated genes in the heart of mice with juvenile visceral steatosis, play a role in the regulation of mitochondrial morphology. We demonstrated that overexpression of Mitogenin I or mtSSB increased elongated or fragmented mitochondria in mouse C2C12 myoblast cells, respectively. On the other hand, the silencing of Mitogenin I or mtSSB by RNA interference led to an increase in fragmented or elongated mitochondria in the cells, respectively, suggesting that Mitogenin I and mtSSB are involved in the processes of mitochondrial fusion and fission, respectively. In addition, we showed that the silencing of Mitogenin I resulted in an increase in the number of trypan blue-positive cells and the silencing of mtSSB resulted in an enhancement of the sensitivity of the cells to apoptotic stimulation by etoposide. The present results demonstrated that these proteins play a role in cell survival.
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Affiliation(s)
- Naokatu Arakaki
- Department of Molecular Cell Biology and Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8505, Japan.
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