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Shahriar S, Ahsan T, Khan A, Akhteruzzaman S, Shehreen S, Sajib AA. Aspartame, acesulfame K and sucralose- influence on the metabolism of Escherichia coli. Metabol Open 2020; 8:100072. [PMID: 33336183 PMCID: PMC7732866 DOI: 10.1016/j.metop.2020.100072] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 11/18/2020] [Accepted: 12/02/2020] [Indexed: 12/13/2022] Open
Abstract
Gut microbes play a crucial role in the maintenance of human health. Components in the diet of the host affect their metabolism and diversity. Here, we investigated the influences of three commonly used non-caloric artificial sweeteners-aspartame, acesulfame K and sucralose-on the growth and metabolism of an omnipresent gut microbe Escherichia coli K-12. Methods: Growth of E. coli in the presence of aspartame, acesulfame K and sucralose in media was assessed and the influences of these artificial sweeteners on metabolism were investigated by relative expression analysis of genes encoding the rate limiting steps of important metabolic pathways as well as their global metabolomic profiles. Results: As a whole, E. coli growth was inhibited by aspartame and induced by acesulfame potassium, while the effect of sucralose on growth was less prominent. Although the expressions of multiple key enzymes that regulate important metabolic pathways were significantly altered by all three sweeteners, acesulfame K caused the most notable changes in this regard. In multivariate analysis with the metabolite profiles, the sucralose-treated cells clustered the closest to the untreated cells, while the acesulfame potassium treated cells were the most distant. These sweeteners affect multiple metabolic pathways in E. coli, which include propanoate, phosphonate, phosphinate and fatty acid metabolism, pentose phosphate pathway, and biosynthesis of several amino acids including lysine and the aromatic amino acids. Similar to the gene expression pattern, acesulfame potassium treated E. coli showed the largest deviation in their metabolite profiles compared to the untreated cells.
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Affiliation(s)
- Shayan Shahriar
- Department of Genetic Engineering & Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - Tamim Ahsan
- Department of Genetic Engineering & Biotechnology, Bangabandhu Sheikh Mujibur Rahman Maritime University, Dhaka, Bangladesh
| | - Abira Khan
- Department of Genetic Engineering & Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - Sharif Akhteruzzaman
- Department of Genetic Engineering & Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - Saadlee Shehreen
- Department of Genetic Engineering & Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - Abu Ashfaqur Sajib
- Department of Genetic Engineering & Biotechnology, University of Dhaka, Dhaka, Bangladesh
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2
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Uram Ł, Misiorek M, Pichla M, Filipowicz-Rachwał A, Markowicz J, Wołowiec S, Wałajtys-Rode E. The Effect of Biotinylated PAMAM G3 Dendrimers Conjugated with COX-2 Inhibitor (celecoxib) and PPARγ Agonist (Fmoc-L-Leucine) on Human Normal Fibroblasts, Immortalized Keratinocytes and Glioma Cells in Vitro. Molecules 2019; 24:molecules24203801. [PMID: 31652556 PMCID: PMC6832538 DOI: 10.3390/molecules24203801] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 10/17/2019] [Accepted: 10/21/2019] [Indexed: 12/31/2022] Open
Abstract
Glioblastoma multiforme (GBM) is the most malignant type of central nervous system tumor that is resistant to all currently used forms of therapy. Thus, more effective GBM treatment strategies are being investigated, including combined therapies with drugs that may cross the blood brain barrier (BBB). Another important issue considers the decrease of deleterious side effects of therapy. It has been shown that nanocarrier conjugates with biotin can penetrate BBB. In this study, biotinylated PAMAM G3 dendrimers substituted with the recognized anticancer agents cyclooxygenase-2 (COX-2) inhibitor celecoxib and peroxisome proliferator-activated receptor γ (PPARγ) agonist Fmoc-L-Leucine (G3-BCL) were tested in vitro on human cell lines with different p53 status: glioblastoma (U-118 MG), normal fibroblasts (BJ) and immortalized keratinocytes (HaCaT). G3-BCL penetrated efficiently into the lysosomal and mitochondrial compartments of U-118 MG cells and induced death of U-118 MG cells via apoptosis and inhibited proliferation and migration at low IC50 = 1.25 µM concentration, considerably lower than either drug applied alone. Comparison of the effects of G3-BCL on expression of COX-2 and PPARγ protein and PGE2 production of three different investigated cell line phenotypes revealed that the anti-glioma effect of the conjugate was realized by other mechanisms other than influencing PPAR-γ expression and regardless of p53 cell status, it was dependent on COX-2 protein level and high PGE2 production. Similar G3-BCL cytotoxicity was seen in normal fibroblasts (IC50 = 1.29 µM) and higher resistance in HaCaT cells (IC50 = 4.49 µM). Thus, G3-BCL might be a good candidate for the targeted, local glioma therapy with limited site effects.
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Affiliation(s)
- Łukasz Uram
- Faculty of Chemistry, Rzeszów University of Technology, 6 Powstańców Warszawy Ave, 35-959 Rzeszów, Poland.
| | - Maria Misiorek
- Faculty of Chemistry, Rzeszów University of Technology, 6 Powstańców Warszawy Ave, 35-959 Rzeszów, Poland.
| | - Monika Pichla
- Faculty of Chemistry, Rzeszów University of Technology, 6 Powstańców Warszawy Ave, 35-959 Rzeszów, Poland.
| | - Aleksandra Filipowicz-Rachwał
- Department of Cosmetics and Pharmaceutical Products Technology, Rzeszów University of Information Technology and Management, 2 Sucharskiego Str, 35-225 Rzeszów, Poland.
| | - Joanna Markowicz
- Faculty of Chemistry, Rzeszów University of Technology, 6 Powstańców Warszawy Ave, 35-959 Rzeszów, Poland.
| | - Stanisław Wołowiec
- Faculty of Medicine, University of Rzeszów, Warzywna 1a, 35-310 Rzeszow, Poland.
| | - Elżbieta Wałajtys-Rode
- Department of Drug Technology and Biotechnology, Faculty of Chemistry, Warsaw University of Technology,75 Koszykowa Str, 00-664 Warsaw, Poland.
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Fake news? Biotin interference in thyroid immunoassays. Clin Chim Acta 2018; 484:320-322. [DOI: 10.1016/j.cca.2018.05.053] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/21/2018] [Accepted: 05/27/2018] [Indexed: 11/21/2022]
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Schreiner D, Savas JN, Herzog E, Brose N, de Wit J. Synapse biology in the 'circuit-age'-paths toward molecular connectomics. Curr Opin Neurobiol 2017; 42:102-110. [PMID: 28033531 PMCID: PMC5316339 DOI: 10.1016/j.conb.2016.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 12/07/2016] [Accepted: 12/08/2016] [Indexed: 11/23/2022]
Abstract
The neural connectome is a critical determinant of brain function. Circuits of precisely wired neurons, and the features of transmission at the synapses connecting them, are thought to dictate information processing in the brain. While recent technological advances now allow to define the anatomical and functional neural connectome at unprecedented resolution, the elucidation of the molecular mechanisms that establish the precise patterns of connectivity and the functional characteristics of synapses has remained challenging. Here, we describe the power and limitations of genetic approaches in the analysis of mechanisms that control synaptic connectivity and function, and discuss how recent methodological developments in proteomics might be used to elucidate the molecular synaptic connectome that is at the basis of the neural connectome.
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Affiliation(s)
- Dietmar Schreiner
- Biozentrum, University of Basel, Klingelbergstraße 50-70, 4056 Basel, Switzerland; Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
| | - Jeffrey N Savas
- Department of Neurology, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
| | - Etienne Herzog
- Univ. Bordeaux, IINS, UMR 5297, F-33000 Bordeaux, France; CNRS, IINS, UMR 5297, F-33000 Bordeaux, France
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Straße 3, 37075 Göttingen, Germany
| | - Joris de Wit
- VIB Center for Brain and Disease Research, Herestraat 49, 3000 Leuven, Belgium; Department of Neurosciences, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.
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Balasubramaniam S, Lewis B, Mock DM, Said HM, Tarailo-Graovac M, Mattman A, van Karnebeek CD, Thorburn DR, Rodenburg RJ, Christodoulou J. Leigh-Like Syndrome Due to Homoplasmic m.8993T>G Variant with Hypocitrullinemia and Unusual Biochemical Features Suggestive of Multiple Carboxylase Deficiency (MCD). JIMD Rep 2016; 33:99-107. [PMID: 27450367 DOI: 10.1007/8904_2016_559] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 03/09/2016] [Accepted: 03/16/2016] [Indexed: 01/15/2023] Open
Abstract
Leigh syndrome (LS), or subacute necrotizing encephalomyelopathy, is a genetically heterogeneous, relentlessly progressive, devastating neurodegenerative disorder that usually presents in infancy or early childhood. A diagnosis of Leigh-like syndrome may be considered in individuals who do not fulfil the stringent diagnostic criteria but have features resembling Leigh syndrome.We describe a unique presentation of Leigh-like syndrome in a 3-year-old boy with elevated 3-hydroxyisovalerylcarnitine (C5-OH) on newborn screening (NBS). Subsequent persistent plasma elevations of C5-OH and propionylcarnitine (C3) as well as fluctuating urinary markers were suggestive of multiple carboxylase deficiency (MCD). Normal enzymology and mutational analysis of genes encoding holocarboxylase synthetase (HLCS) and biotinidase (BTD) excluded MCD. Biotin uptake studies were normal excluding biotin transporter deficiency. His clinical features at 13 months of age comprised psychomotor delay, central hypotonia, myopathy, failure to thrive, hypocitrullinemia, recurrent episodes of decompensation with metabolic keto-lactic acidosis and an episode of hyperammonemia. Biotin treatment from 13 months of age was associated with increased patient activity, alertness, and attainment of new developmental milestones, despite lack of biochemical improvements. Whole exome sequencing (WES) analysis failed to identify any other variants which could likely contribute to the observed phenotype, apart from the homoplasmic (100%) m.8993T>G variant initially detected by mitochondrial DNA (mtDNA) sequencing.Hypocitrullinemia has been reported in patients with the m.8993T>G variant and other mitochondrial disorders. However, persistent plasma elevations of C3 and C5-OH have previously only been reported in one other patient with this homoplasmic mutation. We suggest considering the m.8993T>G variant early in the diagnostic evaluation of MCD-like biochemical disturbances, particularly when associated with hypocitrullinemia on NBS and subsequent confirmatory tests. An oral biotin trial is also warranted.
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Affiliation(s)
- Shanti Balasubramaniam
- Metabolic Unit, Department of Rheumatology and Metabolic Medicine, Princess Margaret Hospital, Perth, WA, Australia. .,School of Paediatrics and Child Health, University of Western Australia, Perth, WA, Australia. .,Western Sydney Genetics Program, Children's Hospital at Westmead, Westmead, NSW, Australia.
| | - B Lewis
- PathWest Laboratories WA, Princess Margaret Hospital, Perth, WA, Australia
| | - D M Mock
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - H M Said
- Department of Medicine, University of California School of Medicine Irvine, Irvine, CA, USA
| | - M Tarailo-Graovac
- Centre for Molecular Medicine, Department of Medical Genetics, Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - A Mattman
- Adult Metabolic Diseases Clinic, Division of Endocrinology and Metabolism, Vancouver General Hospital, UBC, Vancouver, BC, Canada
| | - C D van Karnebeek
- Centre for Molecular Medicine, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - D R Thorburn
- Murdoch Childrens Research Institute and Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, VIC, Australia
| | - R J Rodenburg
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - J Christodoulou
- Murdoch Childrens Research Institute and Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, VIC, Australia
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Peyro Saint Paul L, Debruyne D, Bernard D, Mock DM, Defer GL. Pharmacokinetics and pharmacodynamics of MD1003 (high-dose biotin) in the treatment of progressive multiple sclerosis. Expert Opin Drug Metab Toxicol 2016; 12:327-44. [PMID: 26699811 DOI: 10.1517/17425255.2016.1136288] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Multiple sclerosis (MS) is a chronic, potentially highly disabling neurological disorder. No disease-modifying treatments are approved in the progressive and not active forms of the disease. AREAS COVERED High doses of biotin were tested in an open-label pilot study involving 23 patients with progressive MS and reported positive results. A randomized, double-blind, placebo-controlled trial in 154 progressive MS patients confirmed the beneficial effect of MD1003 (high-dose biotin) on reversing or stabilizing disability progression, with a good safety profile. It is proposed that MD1003 in progressive MS 1) increases energy production in demyelinated axons and/or 2) enhances myelin synthesis in oligodendrocytes. Biotin is highly bioavailable; absorption and excretion are rapid. The major route of elimination is urinary excretion. EXPERT OPINION A high oral dose of biotin seems generally well tolerated but a few important safety concerns were identified: 1) teratogenicity in one species and 2) interference with some biotin-based laboratory immunoassays. The animal toxicity data are limited at such high doses. Further preclinical studies would be useful to address the mechanism of action of MD1003. Assessment of clinical benefit duration in responders will be also very important to set. Results of randomized, placebo-controlled trial are reassuring and provide hope for the treatment of progressive MS.
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Affiliation(s)
| | - Danièle Debruyne
- b Pharmacology , Centre Hospitalier Universitaire de Caen , Caen , France
| | - Delphine Bernard
- c MedDay Pharmaceuticals , ICM-Brain and Spine Institute-IPEPs, Groupe Hospitalier Pitié Salpêtrière , Paris , France
| | - Donald M Mock
- d Department of Biochemistry & Molecular Biology and Pediatrics , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Gilles L Defer
- e Neurology , Centre Hospitalier Universitaire de Caen , Caen , France.,f INSERM U 919 , GIP Cyceron , Caen , France
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Sedel F, Bernard D, Mock DM, Tourbah A. Targeting demyelination and virtual hypoxia with high-dose biotin as a treatment for progressive multiple sclerosis. Neuropharmacology 2015; 110:644-653. [PMID: 26327679 DOI: 10.1016/j.neuropharm.2015.08.028] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 07/24/2015] [Accepted: 08/18/2015] [Indexed: 12/30/2022]
Abstract
Progressive multiple sclerosis (MS) is a severely disabling neurological condition, and an effective treatment is urgently needed. Recently, high-dose biotin has emerged as a promising therapy for affected individuals. Initial clinical data have shown that daily doses of biotin of up to 300 mg can improve objective measures of MS-related disability. In this article, we review the biology of biotin and explore the properties of this ubiquitous coenzyme that may explain the encouraging responses seen in patients with progressive MS. The gradual worsening of neurological disability in patients with progressive MS is caused by progressive axonal loss or damage. The triggers for axonal loss in MS likely include both inflammatory demyelination of the myelin sheath and primary neurodegeneration caused by a state of virtual hypoxia within the neuron. Accordingly, targeting both these pathological processes could be effective in the treatment of progressive MS. Biotin is an essential co-factor for five carboxylases involved in fatty acid synthesis and energy production. We hypothesize that high-dose biotin is exerting a therapeutic effect in patients with progressive MS through two different and complementary mechanisms: by promoting axonal remyelination by enhancing myelin production and by reducing axonal hypoxia through enhanced energy production. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.
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Affiliation(s)
- Frédéric Sedel
- MedDay Pharmaceuticals, ICM-Brain and Spine Institute-IPEPs, Groupe Hospitalier Pitié Salpêtrière, 47 Boulevard de l'Hopital, 75013 Paris, France.
| | - Delphine Bernard
- MedDay Pharmaceuticals, ICM-Brain and Spine Institute-IPEPs, Groupe Hospitalier Pitié Salpêtrière, 47 Boulevard de l'Hopital, 75013 Paris, France.
| | - Donald M Mock
- Department of Biochemistry & Molecular Biology, University of Arkansas for Medical Sciences, 4301 W Markham Street, Little Rock, AR 72205, USA; Department of Pediatrics, University of Arkansas for Medical Sciences, 4301 W Markham Street, Little Rock, AR 72205, USA.
| | - Ayman Tourbah
- Department of Neurology and Faculté de Médecine de Reims, CHU de Reims, URCA, 45 Rue Cognacq Jay, 51092 Reims Cedex, France.
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Abstract
The eradication of cancer remains a vexing problem despite recent advances in our understanding of the molecular basis of neoplasia. One therapeutic approach that has demonstrated potential involves the selective targeting of radionuclides to cancer-associated cell surface antigens using monoclonal antibodies. Such radioimmunotherapy (RIT) permits the delivery of a high dose of therapeutic radiation to cancer cells, while minimizing the exposure of normal cells. Although this approach has been investigated for several decades, the cumulative advances in cancer biology, antibody engineering and radiochemistry in the past decade have markedly enhanced the ability of RIT to produce durable remissions of multiple cancer types.
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Affiliation(s)
- Steven M Larson
- Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| | - Jorge A Carrasquillo
- Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| | - Nai-Kong V Cheung
- 1] Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA. [2]
| | - Oliver W Press
- 1] Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, P.O. BOX 19024, Seattle, Washington 98109, USA. [2]
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Sedel F, Papeix C, Bellanger A, Touitou V, Lebrun-Frenay C, Galanaud D, Gout O, Lyon-Caen O, Tourbah A. High doses of biotin in chronic progressive multiple sclerosis: a pilot study. Mult Scler Relat Disord 2015; 4:159-69. [PMID: 25787192 DOI: 10.1016/j.msard.2015.01.005] [Citation(s) in RCA: 155] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 12/26/2014] [Accepted: 01/12/2015] [Indexed: 12/12/2022]
Abstract
BACKGROUND No drug has been found to have any impact on progressive multiple sclerosis (MS). Biotin is a vitamin acting as a coenzyme for carboxylases involved in key steps of energy metabolism and fatty acids synthesis. Among others, biotin activates acetylCoA carboxylase, a potentially rate-limiting enzyme in myelin synthesis. OBJECTIVES The aim of this pilot study is to assess the clinical efficacy and safety of high doses of biotin in patients suffering from progressive MS. STUDY DESIGN Uncontrolled, non-blinded proof of concept study METHODS 23 consecutive patients with primary and secondary progressive MS originated from three different French MS reference centers were treated with high doses of biotin (100-300mg/day) from 2 to 36 months (mean=9.2 months). Judgement criteria varied according to clinical presentations and included quantitative and qualitative measures. RESULTS In four patients with prominent visual impairment related to optic nerve injury, visual acuity improved significantly. Visual evoked potentials in two patients exhibited progressive reappearance of P100 waves, with normalization of latencies in one case. Proton magnetic resonance spectroscopy (H-MRS) in one case showed a progressive normalization of the Choline/Creatine ratio. One patient with left homonymous hemianopia kept on improving from 2 to 16 months following treatment׳s onset. Sixteen patients out of 18 (89%) with prominent spinal cord involvement were considered as improved as confirmed by blinded review of videotaped clinical examination in 9 cases. In all cases improvement was delayed from 2 to 8 months following treatment׳s onset. CONCLUSIONS These preliminary data suggest that high doses of biotin might have an impact on disability and progression in progressive MS. Two double-blind placebo-controlled trials are on going.
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Affiliation(s)
- Frédéric Sedel
- Neurology Department, AP-HP, Salpêtrière Hospital, Paris, France; Neuro-Metabolic Unit and Reference Center for Lysosomal Diseases, GRC13UPMC, Pierre & Marie Curie University-Paris 6, AP-HP, Salpêtrière Hospital, Paris, France
| | - Caroline Papeix
- Neurology Department, AP-HP, Salpêtrière Hospital, Paris, France
| | | | - Valérie Touitou
- Department of Ophthalmology, AP-HP, Salpêtrière Hospital, Paris, France
| | | | - Damien Galanaud
- Department of Neuroradiology, Pierre & Marie Curie University-Paris 6, Paris, France
| | - Olivier Gout
- Department of Neurology, Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
| | | | - Ayman Tourbah
- Neurology Department, CHU de Reims & Faculté de Médecine de Reims, Champagne-Ardennes University, France; Laboratoire de Psychopathologie et de Neuropsychologie, EA 2027 Paris VIII University, Saint Denis, France.
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Hemmer R, Hall A, Spaulding R, Rossow B, Hester M, Caroway M, Haskamp A, Wall S, Bullen HA, Morris C, Haik KL. Analysis of biotinylated generation 4 poly(amidoamine) (PAMAM) dendrimer distribution in the rat brain and toxicity in a cellular model of the blood-brain barrier. Molecules 2013; 18:11537-52. [PMID: 24048286 PMCID: PMC6269868 DOI: 10.3390/molecules180911537] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 09/03/2013] [Accepted: 09/10/2013] [Indexed: 01/02/2023] Open
Abstract
Dendrimers are highly customizable nanopolymers with qualities that make them ideal for drug delivery. The high binding affinity of biotin/avidin provides a useful approach to fluorescently label synthesized dendrimer-conjugates in cells and tissues. In addition, biotin may facilitate delivery of dendrimers through the blood-brain barrier (BBB) via carrier-mediated endocytosis. The purpose of this research was to: (1) measure toxicity using lactate dehydrogenase (LDH) assays of generation (G)4 biotinylated and non-biotinylated poly(amidoamine) (PAMAM) dendrimers in a co-culture model of the BBB, (2) determine distribution of dendrimers in the rat brain, kidney, and liver following systemic administration of dendrimers, and (3) conduct atomic force microscopy (AFM) on rat brain sections following systemic administration of dendrimers. LDH measurements showed that biotinylated dendrimers were toxic to cell co-culture after 48 h of treatment. Distribution studies showed evidence of biotinylated and non-biotinylated PAMAM dendrimers in brain. AFM studies showed evidence of dendrimers only in brain tissue of treated rats. These results indicate that biotinylation does not decrease toxicity associated with PAMAM dendrimers and that biotinylated PAMAM dendrimers distribute in the brain. Furthermore, this article provides evidence of nanoparticles in brain tissue following systemic administration of nanoparticles supported by both fluorescence microscopy and AFM.
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Affiliation(s)
- Ruth Hemmer
- Department of Biological Sciences, Northern Kentucky University, SC 204, Highland Heights, KY 41099, USA; E-Mails: (R.H.); (A.H.); (R.S.); (B.R.); (M.H.); (M.C.)
| | - Andrew Hall
- Department of Biological Sciences, Northern Kentucky University, SC 204, Highland Heights, KY 41099, USA; E-Mails: (R.H.); (A.H.); (R.S.); (B.R.); (M.H.); (M.C.)
- Department of Chemistry, Northern Kentucky University, SC 450, Highland Heights, KY 41099, USA; E-Mails: (A.H.); (S.W.)
| | - Robert Spaulding
- Department of Biological Sciences, Northern Kentucky University, SC 204, Highland Heights, KY 41099, USA; E-Mails: (R.H.); (A.H.); (R.S.); (B.R.); (M.H.); (M.C.)
| | - Brett Rossow
- Department of Biological Sciences, Northern Kentucky University, SC 204, Highland Heights, KY 41099, USA; E-Mails: (R.H.); (A.H.); (R.S.); (B.R.); (M.H.); (M.C.)
| | - Michael Hester
- Department of Biological Sciences, Northern Kentucky University, SC 204, Highland Heights, KY 41099, USA; E-Mails: (R.H.); (A.H.); (R.S.); (B.R.); (M.H.); (M.C.)
| | - Megan Caroway
- Department of Biological Sciences, Northern Kentucky University, SC 204, Highland Heights, KY 41099, USA; E-Mails: (R.H.); (A.H.); (R.S.); (B.R.); (M.H.); (M.C.)
| | - Anthony Haskamp
- Department of Chemistry, Northern Kentucky University, SC 450, Highland Heights, KY 41099, USA; E-Mails: (A.H.); (S.W.)
| | - Steven Wall
- Department of Chemistry, Northern Kentucky University, SC 450, Highland Heights, KY 41099, USA; E-Mails: (A.H.); (S.W.)
| | - Heather A. Bullen
- Department of Chemistry, Northern Kentucky University, SC 450, Highland Heights, KY 41099, USA; E-Mails: (A.H.); (S.W.)
| | - Celeste Morris
- Department of Chemistry, Northern Kentucky University, SC 450, Highland Heights, KY 41099, USA; E-Mails: (A.H.); (S.W.)
- Authors to whom correspondence should be addressed; E-Mails: (K.L.H.); (C.M.); Tel.: +1-859-572-1965 (K.L.H.); Fax: +1-859-572-5639(K.L.H.); Tel.: +1-859-572-5406 (C.M.); Fax: +1-859-572-5162 (C.M.)
| | - Kristi L. Haik
- Department of Biological Sciences, Northern Kentucky University, SC 204, Highland Heights, KY 41099, USA; E-Mails: (R.H.); (A.H.); (R.S.); (B.R.); (M.H.); (M.C.)
- Center for Integrative Natural Science and Mathematics (CINSAM), Northern Kentucky University, FH 519, Highland Heights, KY 41099, USA
- Authors to whom correspondence should be addressed; E-Mails: (K.L.H.); (C.M.); Tel.: +1-859-572-1965 (K.L.H.); Fax: +1-859-572-5639(K.L.H.); Tel.: +1-859-572-5406 (C.M.); Fax: +1-859-572-5162 (C.M.)
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Hoerbelt P, Nalwalk JW, Phillips JG, Wentland MP, Shan Z, Hough LB. Antinociceptive activity of CC44, a biotinylated improgan congener. Eur J Pharmacol 2013; 714:464-71. [PMID: 23834775 DOI: 10.1016/j.ejphar.2013.06.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 06/17/2013] [Accepted: 06/21/2013] [Indexed: 11/28/2022]
Abstract
Improgan, a non-opioid, antinociceptive drug, activates descending analgesic circuits following brain administration, but the improgan receptor remains unidentified. Since biotinylation of drugs can enhance drug potency or facilitate discovery of new drug targets, a biotinylated congener of improgan (CC44) and several related compounds were synthesized and tested for antinociceptive activity. In rats and mice, intracerebroventricular (i.c.v.) administration of CC44 produced dose-dependent reductions in thermal nociceptive (tail flick and hot plate) responses, with 5-fold greater potency than improgan. CC44 also robustly attenuated mechanical (tail pinch) nociception in normal rats and mechanical allodynia in a spinal nerve ligation model of neuropathic pain. Similar to the effects of improgan, CC44 antinociception was reversed by the GABAA agonist muscimol (consistent with activation of analgesic circuits), and was resistant to the opioid antagonist naltrexone (implying a non-opioid mechanism). Also like improgan, CC44 produced thermal antinociception when microinjected into the rostral ventromedial medulla (RVM). Unlike improgan, CC44 (i.c.v.) produced antinociception which was resistant to antagonism by the cannabinoid CB1 antagonist/inverse agonist rimonabant. CC44 was inactive in mice following systemic administration, indicating that CC44 does not penetrate the brain. Preliminary findings with other CC44 congeners suggest that the heteroaromatic nucleus (imidazole), but not the biotin moiety, is required for CC44's antinociceptive activity. These findings demonstrate that CC44 is a potent analgesic compound with many improgan-like characteristics. Since powerful techniques are available to characterize and identify the binding partners for biotin-containing ligands, CC44 may be useful in searching for new receptors for analgesic drugs.
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Affiliation(s)
- Paul Hoerbelt
- Center for Neuropharmacology and Neuroscience, Albany Medical College MC-136, 47 New Scotland Avenue, Albany, NY 12208, USA
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Van Hove JLK, Josefsberg S, Freehauf C, Thomas JA, Thuy LP, Barshop BA, Woontner M, Mock DM, Chiang PW, Spector E, Meneses-Morales I, Cervantes-Roldán R, León-Del-Río A. Management of a patient with holocarboxylase synthetase deficiency. Mol Genet Metab 2008; 95:201-5. [PMID: 18974016 PMCID: PMC2630166 DOI: 10.1016/j.ymgme.2008.09.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Accepted: 09/12/2008] [Indexed: 11/21/2022]
Abstract
We investigated in a patient with holocarboxylase synthetase deficiency, the relation between the biochemical and genetic factors of the mutant protein with the pharmacokinetic factors of successful biotin treatment. A girl exhibited abnormal skin at birth, and developed in the first days of life neonatal respiratory distress syndrome and metabolic abnormalities diagnostic of multiple carboxylase deficiency. Enzyme assays showed low carboxylase activities. Fibroblast analysis showed poor incorporation of biotin into the carboxylases, and low transfer of biotin by the holocarboxylase synthetase enzyme. Kinetic studies identified an increased Km but a preserved Vmax. Mutation analysis showed the child to be a compound heterozygote for a new nonsense mutation Q379X and for a novel missense mutation Y663H. This mutation affects a conserved amino acid, which is located the most 3' of all recorded missense mutations thus far described, and extends the region of functional biotin interaction. Treatment with biotin 100mg/day gradually improved the biochemical abnormalities in blood and in cerebrospinal fluid (CSF), corrected the carboxylase enzyme activities, and provided clinical stability and a normal neurodevelopmental outcome. Plasma concentrations of biotin were increased to more than 500 nM, thus exceeding the increased Km of the mutant enzyme. At these pharmacological concentrations, the CSF biotin concentration was half the concentration in blood. Measuring these pharmacokinetic variables can aid in optimizing treatment, as individual tailoring of dosing to the needs of the mutation may be required.
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13
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Bogusiewicz A, Stratton SL, Ellison DA, Mock DM. Biotin accounts for less than half of all biotin and biotin metabolites in the cerebrospinal fluid of children. Am J Clin Nutr 2008; 88:1291-6. [PMID: 18996865 PMCID: PMC3097470 DOI: 10.3945/ajcn.2008.26525] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Biotin is likely transported into cerebral spinal fluid (CSF) via one or more specific transporters. Concentrations of biotin in CSF measured by using modern analytic techniques that are specific for biotin and biotin metabolites have not previously been reported. OBJECTIVES We aimed to accurately measure the concentration of biotin and major biotin metabolites, biotin sulfoxide (BSO) and bisnorbiotin (BNB), in the CSF of children. DESIGN Concentrations of biotin were determined initially as total avidin-binding substances (TABS) in CSF obtained by lumbar puncture from 55 children. Biotin, BSO, and BNB were quantitated by HPLC and an avidin-binding assay in CSF samples from a subset of 11 children. RESULTS Concentrations of TABS in CSF averaged 1.6 nmol/L with substantial variability (SD = 1.3 nmol/L). CSF concentrations of biotin and biotin analogs varied widely, but substantial amounts of BSO were detected in every sample. Biotin accounted for 42 +/- 16%, BSO for 41 +/- 12%, and BNB for 8 +/- 14% of the total. It was surprising that the molar sum of biotin, BSO, and BNB on average was >200-fold the TABS concentrations from the same CSF sample. Using several analytic approaches, we found no masking of detection, nor did we find degradation of biotin or BSO. Gel electrophoresis and streptavidin Western blot detected several biotinylated proteins in CSF. CONCLUSIONS Biotin appears to be bound to protein covalently, reversibly, or both, and this binding likely accounts for the increase in detectable biotin after HPLC. Protein-bound biotin may play an important role in biotin nutriture of the brain.
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Affiliation(s)
- Anna Bogusiewicz
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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14
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Spector R, Johanson CE. REVIEW: Vitamin transport and homeostasis in mammalian brain: focus on Vitamins B and E. J Neurochem 2007; 103:425-38. [PMID: 17645457 DOI: 10.1111/j.1471-4159.2007.04773.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
With the application of genetic and molecular biology techniques, there has been substantial progress in understanding how vitamins are transferred across the mammalian blood-brain barrier and choroid plexus into brain and CSF and how vitamin homeostasis in brain is achieved. In most cases (with the exception of the sodium-dependent multivitamin transporter for biotin, pantothenic acid, and lipoic acid), the vitamins are transported by separate carriers through the blood-brain barrier or choroid plexus. Then the vitamins are accumulated by brain cells by separate, specialized systems. This review focuses on six vitamins (B(1), B(3), B(6), pantothenic acid, biotin, and E) and the newer genetic information including relevant 'knockdown' or 'knockout' models in mice and humans. The overall objective is to integrate this newer information with previous physiological and biochemical observations to achieve a better understanding of vitamin transport and homeostasis in brain. This is especially important in view of the newly described non-cofactor vitamin roles in brain (e.g. of B(1), B(3), B(6), and E) and the potential roles of vitamins in the therapy of brain disorders.
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Affiliation(s)
- Reynold Spector
- Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
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Park S, Sinko PJ. The blood-brain barrier sodium-dependent multivitamin transporter: a molecular functional in vitro-in situ correlation. Drug Metab Dispos 2005; 33:1547-54. [PMID: 16033951 DOI: 10.1124/dmd.105.005231] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The molecular mechanism of biotin brain uptake was investigated using an in vitro bovine blood-brain barrier (BBB) cell model and an in situ mouse brain perfusion technique. A functional uptake/transport correlation of the in vitro and in situ characteristics of biotin uptake was investigated. Morphological and immunochemical characteristics (e.g., factor VIII expression) of the primary culture of brain microvessel endothelial cells (BMECs) were confirmed. Gene expression of the multidrug resistance (Mdr1) and sodium-dependent multivitamin (SMVT) transporters was also determined in BMECs. Biotin transport was saturable and Na(+)-dependent at the luminal side of the BBB. The estimated half-saturation concentrations (K(m)) of biotin uptake in vitro and in situ were 49.1 and 35.5 microM, respectively, supporting the presence of a carrier-mediated biotin transport system. Inhibition studies using various biotin derivatives and structural analogs demonstrated the structural requirements for biotin-SMVT interaction. Desthiobiotin and pantothenic acid significantly inhibited the uptake of biotin, whereas 2-iminobiotin and diaminobiotin were very weak inhibitors. Based on our results, there was a good correlation between the in vitro and in situ BBB models, suggesting that when a single membrane transporter is involved in substrate uptake, flexibility in choosing the experimental model can be afforded. The current results are also consistent with the suggestion that the properties of the BBB are likely to be organ-specific rather than species-specific. Further mechanistic and comparative studies are needed to validate these results. In conclusion, the in vitro transporter-based mechanism studies produced valuable molecular functional transport results that correlated well with in situ results.
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Affiliation(s)
- Seonghee Park
- Rutgers University, Ernest Mario School of Pharmacy, 160 Frelinghuysen Road, Piscataway, NJ 08854, USA
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16
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McKay BE, Molineux ML, Turner RW. Biotin is endogenously expressed in select regions of the rat central nervous system. J Comp Neurol 2004; 473:86-96. [PMID: 15067720 DOI: 10.1002/cne.20109] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The vitamin biotin is an endogenous molecule that acts as an important cofactor for several carboxylases in the citric acid cycle. Disorders of biotin metabolism produce neurological symptoms that range from ataxia to sensory loss, suggesting the presence of biotin in specific functional systems of the CNS. Although biotin has been described in some cells of nonmammalian nervous systems, the distribution of biotin in mammalian CNS is virtually unknown. We report the presence of biotin in select regions of rat CNS, as revealed with a monoclonal antibody directed against biotin and with avidin- and streptavidin-conjugated labels. Detectable levels of biotin were primarily found caudal to the diencephalon, with greatest expression in the cerebellar motor system and several brainstem auditory nuclei. Biotin was found as a somatic label in cerebellar Purkinje cells, in cell bodies and proximal dendrites of cerebellar deep nuclear neurons, and in red nuclear neurons. Biotin was detected in cells of the spiral ganglion, somata and proximal dendrites of cells in the cochlear nuclei, superior olivary nuclei, medial nucleus of the trapezoid body, and nucleus of the lateral lemniscus. Biotin was further found in pontine nuclei and fiber tracts, the substantia nigra pars reticulata, lateral mammillary nucleus, and a small number of hippocampal interneurons. Biotin was detected in glial cells of major tract systems throughout the brain but was most prominent in tracts of the hindbrain. Biotin is thus expressed in select regions of rat CNS with a distribution that correlates to the known clinical sequelae associated with biotin deficiencies.
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Affiliation(s)
- Bruce E McKay
- Neuroscience Research Group, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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17
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Valenciano AI, Mayordomo R, de La Rosa EJ, Hallböök F. Biotin decreases retinal apoptosis and induces eye malformations in the early chick embryo. Neuroreport 2002; 13:297-9. [PMID: 11930126 DOI: 10.1097/00001756-200203040-00010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Proliferation, cell death and differentiation occur simultaneously in developing retina and are precisely orchestrated. We have studied the effects of biotin (vitamin H) on early retinal development. In vivo administration of biotin to early embryonic chick eyes at moderately elevated levels induced malformations, affecting retina and lens structures. The effects were strictly age dependent and were only found in embryos treated between Hamburger and Hamilton stage 14-17. Biocytin, a biotin analogue, mimicked biotin effects, while avidin could block the effects. At the cellular level, biotin did not affect proliferation but reduced apoptosis. These results suggest that an adequate content of biotin and a precise regulation of retinal cell death are required for the correct morphogenesis of the eye.
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Affiliation(s)
- Ana I Valenciano
- Department of Neuroscience, Uppsala University, S-75123 Uppsala, Sweden
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18
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Wang KS, Kearns GL, Mock DM. The clearance and metabolism of biotin administered intravenously to pigs in tracer and physiologic amounts is much more rapid than previously appreciated. J Nutr 2001; 131:1271-8. [PMID: 11285337 DOI: 10.1093/jn/131.4.1271] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Understanding of biotin pharmacokinetics and regulation of metabolism is essential for the determination of the biotin requirement for humans. Using Landrace-Cambrough pigs as a model, we initially demonstrated that biotin binding to protein accounts for only a small percentage of the total biotin in plasma. A physiologic amount of [14C]biotin was administered intravenously to three pigs; nine blood samples were collected over 48 h. Plasma concentrations of 14C-labeled metabolites were negligible for the first 2 h after biotin infusion. Disappearance curves of total 14C and of [14C]biotin were similar; both fit a triexponential function consistent with a three-compartment, open model. To characterize the rapid early phase of disappearance more precisely, a physiologic amount of [14C]biotin was administered intravenously to five pigs; eight blood samples were collected over the first hour and 16 total samples over 48 h. Again a triexponential function provided an excellent fit. The mean half-life values (+/- 1 SD) for the three phases were 0.11 +/- 0.07, 1.43 +/- 0.42 and 22 +/- 4 h. The [14C]biotin accumulated primarily in the liver, kidney and muscle. When administered intravenously at tracer doses to three pigs, [3H]biotin exhibited similar early pharmacokinetics; however, substantial quantities of a 3H-labeled metabolite appeared after 1 h. These studies provide evidence that egress of biotin from plasma is more rapid than previously appreciated. The slower second and third phases may represent transport into the cytosol, biotransformation into intermediates and covalent binding to intracellular proteins. Similar pharmacokinetics are likely to be seen in humans.
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Affiliation(s)
- K S Wang
- Department of Biochemistry & Molecular Biology, University of Arkansas for Medical Sciences and Arkansas Children's Hospital Research Institute, Little Rock, AR 72205, USA
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Baur B, Baumgartner ER. Biotin and biocytin uptake into cultured primary calf brain microvessel endothelial cells of the blood-brain barrier. Brain Res 2000; 858:348-55. [PMID: 10708686 DOI: 10.1016/s0006-8993(00)01944-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The uptake of biotin and the closely related biocytin was characterized in primary cultures of calf brain microvessel endothelial (CBME) cells. Biotin uptake was found to be Na(+)-gradient dependent and independent of changes in the membrane potential. Concentration dependence revealed a single saturation mechanism with a K(m) of 47 microM and a V(max) of 101 pmol/min/mg. Inhibition studies demonstrated dependence on metabolic energy and the necessity for a free carboxyl group for transport activity. The anticonvulsants primidone and carbamazepine had no inhibitory effect. Biotin uptake into CBME cells is a secondary active, electroneutral, saturable and specific process. Biocytin which accumulates in biotinidase deficiency, a human congenital disorder, did not inhibit biotin uptake and was not transported into these cells. The presence of human serum with normal biotinidase activity significantly reduced biotin uptake by about 50%. Further, added biocytin was hydrolyzed to biotin, which accumulated intracellularly but to a lesser extent than added free biotin. Biotin uptake after addition of plasma of biotinidase-deficient patients was not different from that in the presence of normal serum. These results indicate that the absence of biotinidase activity in serum does not reduce blood-brain barrier transport of biotin.
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Affiliation(s)
- B Baur
- Metabolic Unit, University Children's Hospital, 4005, Basel, Switzerland.
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20
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Abstract
Prominent displays of endogenous biotin reactivity can be observed at specific locations in histochemical preparations of the forebrain and midbrain in the northern leopard frog (Rana pipiens) and common American toad (Bufo americanus). At the light microscopic level, the biotin reactivity appears in clusters of darkly stained puncta of either spherical or rodlike shape in the olfactory cortex, nucleus isthmi, and hypothalamus. With the electron microscope, the biotin reactive spheres are identified as neuronal varicosities and synaptic boutons and the rods as short segments of axons. Appropriate controls demonstrate that the punctate biotin-reactive structures are sites of concentration of biotin or a biotin analog in the processes of certain neurons. These data represent the first observation on the selective concentration of a vitamin in vertebrate neurons and suggest that biotin may have specialized functions in anatomically delimited areas of the central nervous system. Localization of the densest concentration of the biotin-reactive puncta in the dorsolateral prominence of the olfactory cortex may have relevance to the functional organization of the olfactory system. The distributions of biotin-reactive puncta were observed in laboratory-housed frogs and in wild toads captured in the summer months but were sparse or absent in batches of commercially obtained frogs examined immediately upon arrival in the laboratory. Systemic administration of biotin or biocytin hydrochloride did not alter the appearance or numbers of the biotin-reactive structures either in newly received or laboratory-housed frogs. These findings suggest that the capacity of the biotin-storage mechanism in the amphibian brain may be set by environmental factors and may be readily saturable from natural dietary or enteric sources.
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Affiliation(s)
- S Eisner
- Department of Anatomy and Cell Biology, State University of New York Health Science Center at Brooklyn 11203, USA
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21
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Schenker S, Hu ZQ, Johnson RF, Yang Y, Frosto T, Elliott BD, Henderson GI, Mock DM. Human placental biotin transport: normal characteristics and effect of ethanol. Alcohol Clin Exp Res 1993; 17:566-75. [PMID: 8333586 DOI: 10.1111/j.1530-0277.1993.tb00801.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Biotin, a vitamin essential for many metabolic reactions, is supplied to the fetus exclusively from the mother. Deficiency of biotin in pregnancy leads to impaired fetal growth and development. Alcohol taken in pregnancy likewise may cause fetal growth abnormalities. Normal biotin transport via the placenta and the effects of ethanol on this transport apparently have not been studied. Our aims were to characterize these phenomena for the normal human-term placenta. Using maternal-facing placental membrane vesicles, biotin uptake was sodium- and temperature-dependent, saturable, and inhibited by structural analogs of biotin (desthiobiotin, biocytin, and biotin methyl ester), as well as by 4 and 10 hr exposure to 3 g/liter ethanol. Using the isolated perfused single cotyledon method to measure placental transport of biotin at a perfusion concentration of 1 nM, the overall rate of biotin transport was found to be only 30% that of antipyrine, a freely diffusible marker. Clearance of biotin was approximately 2 ml/hr.g placenta, which was equal to the clearance of passively transferred L-glucose; biotin clearance was similar in both maternal to fetal and fetal to maternal directions. Overall transfer of biotin from maternal to fetal compartments was not inhibited by 500-fold greater concentrations of the three analogs, did not proceed against a biotin concentration gradient, and was not inhibited by 90-240 min exposure to an initial concentration of 4 g/liter ethanol. Concentration of biotin in the fetal compartment at the end of the study was not higher than on the maternal side (after maternal to fetal infusion), but placental concentration was 2- to 3-fold greater. No significant metabolism of biotin was detected. Exposing human placental cultured trophoblast on day 3 to 24 hr of ethanol (2 g/liter) had no effect on the net uptake of biotin by these cells. These studies provide evidence that maternal-facing placental membranes take up biotin by a mediated, carrier-dependent process that is inhibited by ethanol; however, based on the perfusion studies, we conclude that the overall (maternal-fetal) rate-limiting transfer of biotin by the human placenta is most consistent with a passive process, which is not inhibited by short-term exposure to ethanol.
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Affiliation(s)
- S Schenker
- Department of Medicine/Division of Gastroenterology and Nutrition, University of Texas Health Science Center, San Antonio 78284-7878
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Baur B, Baumgartner ER. Na(+)-dependent biotin transport into brush-border membrane vesicles from human kidney cortex. Pflugers Arch 1993; 422:499-505. [PMID: 8474852 DOI: 10.1007/bf00375078] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Renal reabsorption of biotin was investigated in human kidney by means of the isolated brush-border membrane vesicle technique. Biotin uptake into the vesicles was sodium-dependent producing a typical overshoot when incubated under sodium-gradient conditions (external concentration greater than internal). This effect was not observed in the presence of gradients of KCl, LiCl or choline-chloride, nor in the absence of any salt. Using the K+/valinomycin voltage-clamp method biotin uptake remained uninfluenced, i.e. was electroneutral, whereas glucose uptake (which is known to be electrogenic in kidney of other species) was greatly increased. When biotin transport was investigated as a function of external sodium concentration a stoichiometic coupling factor of 1 for the Na(+)-biotin- cotransport was determined. Increasing the biotin concentration in the incubation medium up to 200 mumol/l led to saturation with the kinetic parameters of 31 mumol/l for the apparent Michaelis constant and 82 nmol g protein-1 30 s-1 for the maximal transport rate. Uptake was not saturable in the concentration range of 0.001-1 mumol/l. Inhibition of the biotin uptake (25 mumol/l) was observed in the presence of 250 mumol/l dethiobiotin, bisnorbiotin, thioctic acid, and probenecid, whereas biocytin, propionic acid, lactic acid, succinic acid, citric acid, ascorbic acid, primidone and carbamazepine had no effect. We conclude that renal biotin reabsorption in human kidney is specifically sodium-dependent, saturable and electroneutral. It therefore fulfills the requirements for a secondary active carrier-mediated transport system. The results suggest that biocytin is not an inhibitor of renal biotin reabsorption.
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Affiliation(s)
- B Baur
- University Children's Hospital, Metabolic Unit, Basel, Switzerland
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Affiliation(s)
- R Spector
- Merck Sharp & Dohme Research Laboratories, Rahway, NJ 07065
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