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4 Hydroxybutyric Acid

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Hideki Abe – One of the best experts on this subject based on the ideXlab platform.

  • Thermal degradation of environmentally degradable poly(hydroxyalkanoic Acid)s.
    Macromolecular bioscience, 2006
    Co-Authors: Hideki Abe
    Abstract:

    Aliphatic polyesters have attracted industrial attention as environmentally degradable thermoplastics to be used for a wide range of applications. Besides intensive studies on the biodegradability of aliphatic polyesters, understanding of the thermal stability has importance for processing, application, and recycling. The details of thermal degradation processes of five types of aliphatic polyesters; namely, poly(L-lactide), poly(3-Hydroxybutyric Acid), poly(4Hydroxybutyric Acid), poly(delta-valerolactone), and poly(epsilon-caprolactone), were investigated by means of several thermoanalytical techniques under both isothermal and non-isothermal conditions. In this feature article, the thermal degradation behaviors of aliphatic polyesters with different numbers of carbon atoms in the main chain of the monomeric unit are reviewed. In addition, the effects of chain-end structure and residual metal compounds on the thermal degradation processes of aliphatic polyesters consisting of hydroxyalkanoic Acid monomeric units are presented. Schemes of thermal degradation reaction of poly(hydroxyalkanoic Acid)s.

  • Thermal degradation behavior of poly(4Hydroxybutyric Acid)
    Polymer Degradation and Stability, 2006
    Co-Authors: Kang Ju Kim, Yoshiharu Doi, Hideki Abe, David P. Martin
    Abstract:

    Abstract Thermal degradation behavior of poly(4Hydroxybutyric Acid) (P(4HB)) was investigated by thermogravimetric and pyrolysis–gas chromatography mass spectrometric analyses under both isothermal and non-isothermal conditions. Based on the thermogravimetric analysis, it was found that two distinct processes occurred at temperatures below and above 350 °C during the non-isothermal degradation of P(4HB) samples depending on both the molecular weight and the heating rate. From 1 H NMR analysis of the residual P(4HB) molecules after isothermal degradations at different temperatures, it was confirmed that the ω-hydroxyl chain-end was remained unchanged in the residual P(4HB) molecules at temperatures below 300 °C, while the ω-chain-end of P(4HB) molecules was converted to 3-butenoyl units at temperatures above 300 °C. In contrast, the majority of the volatile products evolved during thermal degradation of P(4HB) was γ-butyrolactone regardless of the degradation temperature. From these results, it is concluded that during the thermal degradation of P(4HB), the selective formation of γ-butyrolactone via unzipping reaction from the ω-hydroxyl chain-end predominantly occurs at temperatures below 300 °C. At temperatures above 300 °C, both the cis -elimination reaction of 4HB unit and the formation of cyclic macromolecules of P(4HB) via intramolecular transesterification take place in addition to unzipping reaction from the ω-hydroxyl chain-end. Finally, the primary reaction of thermal degradation of P(4HB) at temperatures above 350 °C progresses by the cyclic rupture via intramolecular transesterification of P(4HB) molecules with a release of γ-butyrolactone as volatile product. Moreover, we carried out the thermal degradation tests for copolymer of 93 mol% of 4HB with 7 mol% of 3-Hydroxybutyric Acid (3HB) to examine the effect of 3HB units on thermal stability of P(4HB).

  • Crystalline morphology and thermal properties for random copolyesters of (R)‐3‐Hydroxybutyric Acid with different hydroxyalkanoic groups
    Macromolecular Symposia, 2001
    Co-Authors: Hideki Abe, Yoshiharu Doi
    Abstract:

    The solid-state structures and thermal properties of melt-crystallized films of random copolymers of (R)-3-Hydroxybutyric Acid (3HB) with different hydroxyalkanoic Acids such as (R)-3-hydroxypentanoic Acid (3HV), (R)-3-hydroxyhexanoic Acid (3HH), medium-chain-length (R)-3-hydroxyalkanoic Acids (mcl-3HA; C8-C12), 4Hydroxybutyric Acid (4HB), and 6-hydroxyhexanoic Acid (6HH) were characterized by means of small-angle X-ray scattering, differential scanning calorimetry, and optical microscopy. The randomly distributed second monomer units except for 3HV in copolyesters act as defects of P(3HB) crystal and are excluded from the P(3HB) crystalline lamellae. The lamellar thickness of copolymers decreased with an increase in either the main-chain or the side-chain carbon numbers of second monomer units. In addition, the growth rate of spherulites decreased with an increase in the carbon numbers of second monomer units for copolymers with an identical comonomer composition. These results indicate that the steric bulkiness of second monomer unit affects on the crystallization of 3HB segments in random copolyesters.

C.a.j.m. Jakobs – One of the best experts on this subject based on the ideXlab platform.

  • Sedation with 4Hydroxybutyric Acid: a potential pitfall in the diagnosis of SSADH deficiency.
    Journal of inherited metabolic disease, 2004
    Co-Authors: Nicole I. Wolf, Dorothea Haas, Georg F. Hoffmann, C.a.j.m. Jakobs, Gajja S. Salomons, Ron A. Wevers, Udo F. H. Engelke, Dietz Rating
    Abstract:

    Deficiency of succinic semialdehyde dehydrogenase (SSADH) is a rare neurometabolic disorder with accumulation of 4Hydroxybutyric Acid (4-HBA) as a biochemical hallmark. We present a boy with an unresolved severe neurological disorder and intermittent elevation of 4-HBA in serum and CSF which was later shown to result from iatrogenic administration of 4-HBA for sedation purposes.

  • 4Hydroxybutyric Acid and the clinical phenotype of succinic semialdehyde dehydrogenase deficiency, an inborn error of GABA metabolism.
    Neuropediatrics, 1998
    Co-Authors: Kenneth M. Gibson, C. F. Hoffmann, A. K. Hodson, Teodoro Bottiglieri, C.a.j.m. Jakobs
    Abstract:

    SSADH deficiency, a rare inborn error of human metabolism, disrupts the normal metabolism of the inhibitory neurotransmitter GABA. In response to the defect, physiologic fluids from patients accumulate GHB, a compound with numerous neuromodulatory properties. Clinical and bio-chemical findings in patients are contrasted with existing neuropharmacologic data on GHB in animals and men. We conclude that GHB contributes to the pathogenesis of SSADH deficiency; whether this effect is mediated by GHB, by GABA following metabolic interconversion, or via synergistic mechanisms by both compounds, remains to be determined. An animal model of SSADH deficiency should further define the role of GHB in the pathogenesis of SSADH deficiency, and provide a useful vehicle for the evaluation of new therapeutic intervention.

  • Differing clinical presentation of succinic semialdehyde dehydrogenase deficiency in adolescent siblings from Lifu Island, New Caledonia
    Journal of inherited metabolic disease, 1997
    Co-Authors: Kenneth M. Gibson, C.a.j.m. Jakobs, Daniel Rabier, A. E. Doskey, C. Morlat
    Abstract:

    Succinic semialdehyde dehydrogenase (SSADH) deficiency (McKusick 271980) is a rare inherited defect in 4-aminobutyric Acid (GABA) metabolism. The primary defect results in the accumulation of succinic semialdehyde, which is reduced to 4Hydroxybutyric Acid, the biochemical marker for the disease and a compound with neurogenic properties (Jakobs et al 1993; Scriver and Gibson 1995). As the number of identified patients is still small, the clinical phenotype of the disease is not yet fully developed. Most patients, who originate primarily from Northern Europe, Asia and North America, present with varying deficiencies of mental, motor and language development, variably accompanied by hypotonia, ataxia, seizures and ocular or reflex abnormalities (Scriver and Gibson 1995). Unrelated patients have presented with considerable heterogeneity in clinical manifestations. However, the clinical presentation within sibships has been more consistent. We report a differing clinical phenotype of SSADH deficiency in adolescent male and female siblings whose parents had migrated from Fiji to Lifu Island, off the Eastern coast of New Caledonia (France).

Kenneth M. Gibson – One of the best experts on this subject based on the ideXlab platform.

  • 4Hydroxybutyric Acid and the clinical phenotype of succinic semialdehyde dehydrogenase deficiency, an inborn error of GABA metabolism.
    Neuropediatrics, 1998
    Co-Authors: Kenneth M. Gibson, C. F. Hoffmann, A. K. Hodson, Teodoro Bottiglieri, C.a.j.m. Jakobs
    Abstract:

    SSADH deficiency, a rare inborn error of human metabolism, disrupts the normal metabolism of the inhibitory neurotransmitter GABA. In response to the defect, physiologic fluids from patients accumulate GHB, a compound with numerous neuromodulatory properties. Clinical and bio-chemical findings in patients are contrasted with existing neuropharmacologic data on GHB in animals and men. We conclude that GHB contributes to the pathogenesis of SSADH deficiency; whether this effect is mediated by GHB, by GABA following metabolic interconversion, or via synergistic mechanisms by both compounds, remains to be determined. An animal model of SSADH deficiency should further define the role of GHB in the pathogenesis of SSADH deficiency, and provide a useful vehicle for the evaluation of new therapeutic intervention.

  • Differing clinical presentation of succinic semialdehyde dehydrogenase deficiency in adolescent siblings from Lifu Island, New Caledonia
    Journal of inherited metabolic disease, 1997
    Co-Authors: Kenneth M. Gibson, C.a.j.m. Jakobs, Daniel Rabier, A. E. Doskey, C. Morlat
    Abstract:

    Succinic semialdehyde dehydrogenase (SSADH) deficiency (McKusick 271980) is a rare inherited defect in 4-aminobutyric Acid (GABA) metabolism. The primary defect results in the accumulation of succinic semialdehyde, which is reduced to 4Hydroxybutyric Acid, the biochemical marker for the disease and a compound with neurogenic properties (Jakobs et al 1993; Scriver and Gibson 1995). As the number of identified patients is still small, the clinical phenotype of the disease is not yet fully developed. Most patients, who originate primarily from Northern Europe, Asia and North America, present with varying deficiencies of mental, motor and language development, variably accompanied by hypotonia, ataxia, seizures and ocular or reflex abnormalities (Scriver and Gibson 1995). Unrelated patients have presented with considerable heterogeneity in clinical manifestations. However, the clinical presentation within sibships has been more consistent. We report a differing clinical phenotype of SSADH deficiency in adolescent male and female siblings whose parents had migrated from Fiji to Lifu Island, off the Eastern coast of New Caledonia (France).

  • Pre- and postnatal diagnosis of succinic semialdehyde dehydrogenase deficiency using enzyme and metabolite assays.
    Journal of inherited metabolic disease, 1994
    Co-Authors: Kenneth M. Gibson, H. Ogier, C. Baumann, Eva Rossier, Brigitte Vollmer, C.a.j.m. Jakobs
    Abstract:

    We Report our cumulative experience for the prenatal diagnosis of succinic semialdehyde dehydrogenase (SSADH) deficiency in seven ‘at-risk’ pregnancies from four unrelated families. Prenatal diagnosis was performed by determination of 4Hydroxybutyric Acid (4-HBA) concentration in amniotic fluid using isotope-dilution gas chromatography-mass spectrometry in conjunction with assay of SSADH activity in biopsied chorionic villus and/or cultured amniocytes. In three of four pregnancies predicted as affected, confirmation was obtained by demonstration of deficient SSADH activity in fetal tissues. Our results suggest that determination of 4-HBA concentration in amniotic fluid combined with enzyme determination in cultured or biopsied tissue represents a reliable method for the prenatal diagnosis of SSADH deficiency.